A BK (Slo1) channel journey from molecule to physiology

PubMed Central

Contreras, Gustavo F; Castillo, Karen; Enrique, Nicolás; Carrasquel-Ursulaez, Willy; Castillo, Juan Pablo; Milesi, Verónica; Neely, Alan; Alvarez, Osvaldo; Ferreira, Gonzalo; González, Carlos; Latorre, Ramón

2013-01-01

Calcium and voltage-activated potassium (BK) channels are key actors in cell physiology, both in neuronal and non-neuronal cells and tissues. Through negative feedback between intracellular Ca2+ and membrane voltage, BK channels provide a damping mechanism for excitatory signals. Molecular modulation of these channels by alternative splicing, auxiliary subunits and post-translational modifications showed that these channels are subjected to many mechanisms that add diversity to the BK channel α subunit gene. This complexity of interactions modulates BK channel gating, modifying the energetic barrier of voltage sensor domain activation and channel opening. Regions for voltage as well as Ca2+ sensitivity have been identified, and the crystal structure generated by the 2 RCK domains contained in the C-terminal of the channel has been described. The linkage of these channels to many intracellular metabolites and pathways, as well as their modulation by extracellular natural agents, has been found to be relevant in many physiological processes. This review includes the hallmarks of BK channel biophysics and its physiological impact on specific cells and tissues, highlighting its relationship with auxiliary subunit expression. PMID:24025517

Quantification of polyoma BK viruria in hemorrhagic cystitis complicating bone marrow transplantation.

PubMed

Leung, A Y; Suen, C K; Lie, A K; Liang, R H; Yuen, K Y; Kwong, Y L

2001-09-15

Polyoma BK virus (BKV) is frequently identified in the urine of bone marrow transplantation (BMT) patients with hemorrhagic cystitis (HC). However, viruria is common even in asymptomatic patients, making a direct causative role of BKV difficult to establish. This study prospectively quantified BK viruria and viremia in 50 BMT patients to define the quantitative relationship of BKV reactivation with HC. Adenovirus (ADV) was similarly quantified as a control. More than 800 patient samples were quantified for BKV VP1 gene with a real-time quantitative polymerase chain reaction. Twenty patients (40%) developed HC, 6 with gross hematuria (HC grade 2 or higher) and 14 with microscopic hematuria (HC grade 1). When compared with asymptomatic patients, patients with HC had significantly higher peak BK viruria (6 x 10(12) versus 5.7 x 10(7) genome copies/d, P <.001) and larger total amounts of BKV excreted during BMT (4.9 x 10(13) versus 7.7 x 10(8) genome copies, P <.001). There was no detectable increase in BK viremia. Binary logistic regression analysis showed that BK viruria was the only risk factor, with HC not related to age, conditioning regimen, type of BMT, and graft-versus-host disease. Furthermore, the levels of ADV viruria in patients with or without HC were similar and comparable with those of BK viruria in patients without HC, suggesting that the significant increase in BK viruria in HC patients was not due to background viral reactivation or damage to the urothelium. BK viruria was quantitatively related to the occurrence of HC after BMT.

A Simple and Reliable Strategy for BK Virus Subtyping and Subgrouping

PubMed Central

Morel, Virginie; Martin, Elodie; François, Catherine; Helle, François; Faucher, Justine; Mourez, Thomas; Choukroun, Gabriel; Duverlie, Gilles; Castelain, Sandrine

2017-01-01

ABSTRACT BK virus (BKV)-associated diseases in transplant recipients are an emerging issue. However, identification of the various BK virus subtypes/subgroups is a long and delicate process on the basis of currently available data. Therefore, we wanted to define a simple and effective one-step strategy for characterizing all BK virus strains from the VP1 gene sequence. Based on the analysis of 199 available complete DNA VP1 sequences, phylogenetic trees, alignments, and isolated polymorphisms were used to define an effective strategy for distinguishing the 12 different BK virus subtypes/subgroups. Based on the 12 subtypes identified from the 199 complete BKV VP1 sequences (1,089 bp), 60 mutations that can be used to differentiate these various subtypes/subgroups were identified. Some genomic areas were more variable and comprised mutational hot spots. From a subregion of only 100 bp in the VP1 region (1977 through 2076), we therefore constructed an algorithm that enabled rapid determination of all BKV subtypes/subgroups with 99% agreement (197/199) relative to the complete VP1 sequence. We called this domain of the BK viral genome the BK typing and grouping region (BKTGR). Finally, we validated our viral subtype identification process in a population of 100 transplant recipients with 100% efficiency. The new simpler method of BKV subtyping/subgrouping reported here constitutes a useful tool for future studies that will help us to more clearly understand the impact of BKV subtypes/subgroups on diagnosis, infection, and BK virus-associated diseases. PMID:28151406

The human polyomavirus BK: Potential role in cancer.

PubMed

Fioriti, D; Videtta, M; Mischitelli, M; Degener, A M; Russo, G; Giordano, A; Pietropaolo, V

2005-08-01

In human cancer, a role has been suggested for the human polyomavirus BK, primarily associated with tubulointerstitial nephritis and ureteric stenosis in renal transplant recipients, and with hemorrhagic cystitis in bone marrow transplant (BMT) recipients. After the initial infection, primarily unapparent and without clinical signs, the virus disseminates and establishes a persistent infection in the urinary tract and lymphocytes. There is correlative evidence regarding potential role of polyomavirus BK in cancer. In fact, the BK virus (BKV) DNA (complete genome and/or subgenomic fragments containing the early region) is able to transform embryonic fibroblasts and cells cultured from kidney and brain of hamster, mouse, rat, rabbit, and monkey. Nevertheless, transformation of human cells by BKV is inefficient and often abortive. Evidence supporting a possible role for BKV in human cancer has accumulated slowly in recent years, after the advent of polymerase chain reaction (PCR). BKV is known to commonly establish persistent infections in people and to be excreted in the urine by individuals who are asymptomatic, complicating the evaluation of its potential role in development of human cancer. Therefore, there is no certain proof that human polyomavirus BK directly causes the cancer in humans or acts as a cofactor in the pathogenesis of some types of human cancer. (c) 2005 Wiley-Liss, Inc.

BK Viremia Precedes Hemorrhagic Cystitis in Children Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

PubMed Central

Laskin, Benjamin L.; Denburg, Michelle; Furth, Susan; Diorio, Donna; Goebel, Jens; Davies, Stella M.; Jodele, Sonata

2013-01-01

BK virus is associated with hemorrhagic cystitis after hematopoietic stem cell transplantation (HSCT), although evidence supporting a causal relationship remains limited. Although BK viruria is common after HSCT, BK viremia may better predict clinically significant cystitis, similar to its predictive value for nephropathy after kidney transplantation. We hypothesized that BK viremia would precede hemorrhagic cystitis in a cohort of 88 consecutive children prospectively enrolled to originally study thrombotic microangiopathy in the first 100 days after allogeneic HSCT. Cox regression models with time-varying covariates assessed the association between different BK viremia cutoffs and the development of hemorrhagic cystitis, defined as at least macroscopic hematuria. Subjects with a peak plasma BK viral load 1 to 9999 copies/mL had an adjusted hazard ratio of 4.2 (95% confidence interval (CI), 1.3 to 13.7) for the development of hemorrhagic cystitis. Those with peak BK viremia >100,000 copies/mL had an adjusted hazard ratio of 116.8 (95% CI, 12 to 1136) for cystitis. Other independent risk factors for hemorrhagic cystitis included age >7 years and HHV-6 viremia. Neither graft-versus-host disease nor achieving engraftment increased the risk for cystitis. If therapeutic strategies are found to be effective, these observations may support screening for BK viremia after HSCT, as currently recommended for other DNA viruses. PMID:23665115

Differential contribution of Ca2+ sources to day and night BK current activation in the circadian clock

PubMed Central

McNally, Beth A.

2018-01-01

Large conductance K+ (BK) channels are expressed widely in neurons, where their activation is regulated by membrane depolarization and intracellular Ca2+ (Ca2+i). To enable this regulation, BK channels functionally couple to both voltage-gated Ca2+ channels (VGCCs) and channels mediating Ca2+ release from intracellular stores. However, the relationship between BK channels and their specific Ca2+ source for particular patterns of excitability is not well understood. In neurons within the suprachiasmatic nucleus (SCN)—the brain’s circadian clock—BK current, VGCC current, and Ca2+i are diurnally regulated, but paradoxically, BK current is greatest at night when VGCC current and Ca2+i are reduced. Here, to determine whether diurnal regulation of Ca2+ is relevant for BK channel activation, we combine pharmacology with day and night patch-clamp recordings in acute slices of SCN. We find that activation of BK current depends primarily on three types of channels but that the relative contribution changes between day and night. BK current can be abrogated with nimodipine during the day but not at night, establishing that L-type Ca2+ channels (LTCCs) are the primary daytime Ca2+ source for BK activation. In contrast, dantrolene causes a significant decrease in BK current at night, suggesting that nighttime BK activation is driven by ryanodine receptor (RyR)–mediated Ca2+i release. The N- and P/Q-type Ca2+ channel blocker ω-conotoxin MVIIC causes a smaller reduction of BK current that does not differ between day and night. Finally, inhibition of LTCCs, but not RyRs, eliminates BK inactivation, but the BK β2 subunit was not required for activation of BK current by LTCCs. These data reveal a dynamic coupling strategy between BK channels and their Ca2+ sources in the SCN, contributing to diurnal regulation of SCN excitability. PMID:29237755

Differential contribution of Ca2+ sources to day and night BK current activation in the circadian clock.

PubMed

Whitt, Joshua P; McNally, Beth A; Meredith, Andrea L

2018-02-05

Large conductance K + (BK) channels are expressed widely in neurons, where their activation is regulated by membrane depolarization and intracellular Ca 2+ (Ca 2+ i ). To enable this regulation, BK channels functionally couple to both voltage-gated Ca 2+ channels (VGCCs) and channels mediating Ca 2+ release from intracellular stores. However, the relationship between BK channels and their specific Ca 2+ source for particular patterns of excitability is not well understood. In neurons within the suprachiasmatic nucleus (SCN)-the brain's circadian clock-BK current, VGCC current, and Ca 2+ i are diurnally regulated, but paradoxically, BK current is greatest at night when VGCC current and Ca 2+ i are reduced. Here, to determine whether diurnal regulation of Ca 2+ is relevant for BK channel activation, we combine pharmacology with day and night patch-clamp recordings in acute slices of SCN. We find that activation of BK current depends primarily on three types of channels but that the relative contribution changes between day and night. BK current can be abrogated with nimodipine during the day but not at night, establishing that L-type Ca 2+ channels (LTCCs) are the primary daytime Ca 2+ source for BK activation. In contrast, dantrolene causes a significant decrease in BK current at night, suggesting that nighttime BK activation is driven by ryanodine receptor (RyR)-mediated Ca 2+ i release. The N- and P/Q-type Ca 2+ channel blocker ω-conotoxin MVIIC causes a smaller reduction of BK current that does not differ between day and night. Finally, inhibition of LTCCs, but not RyRs, eliminates BK inactivation, but the BK β2 subunit was not required for activation of BK current by LTCCs. These data reveal a dynamic coupling strategy between BK channels and their Ca 2+ sources in the SCN, contributing to diurnal regulation of SCN excitability. © 2018 Whitt et al.

Outcomes of renal transplant recipients with BK virus infection and BK virus surveillance in the Auckland region from 2006 to 2012.

PubMed

Hsiao, Chun-Yuan; Pilmore, Helen L; Zhou, Lifeng; de Zoysa, Janak R

2016-11-06

To evaluate incidence, risk factors and treatment outcome of BK polyomavirus nephropathy (BKVN) in a cohort of renal transplant recipients in the Auckland region without a formal BK polyomavirus (BKV) surveillance programme. A cohort of 226 patients who received their renal transplants from 2006 to 2012 was retrospectively reviewed. Seventy-six recipients (33.6%) had a BK viral load (BKVL) test and 9 patients (3.9%) developed BKVN. Cold ischaemia time (HR = 1.18, 95%CI: 1.04-1.35) was found to be a risk factor for BKVN. Four recipients with BKVN had complete resolution of their BKV infection; 1 recipient had BKVL less than 625 copies/mL; 3 recipients had BKVL more than 1000 copies/mL and 1 had graft failure from BKVN. BKVN has a negative impact on graft function [median estimated glomerular filtration rate (eGFR) 22.5 (IQR 18.5-53.0) mL/min per 1.73 m 2 , P = 0.015), but no statistically significant difference ( P = 0.374) in renal allograft function was found among negative BK viraemia group [median eGFR 60.0 (IQR 48.5-74.2) mL/min per 1.73 m 2 ), positive BK viraemia without BKVN group [median eGFR 55.0 (IQR 47.0-76.0) mL/min per 1.73 m 2 ] and unknown BKV status group [median eGFR 54.0 (IQR 43.8-71.0) mL/min per 1.73 m 2 ]. The incidence and treatment outcomes of BKVN were similar to some centres with BKV surveillance programmes. Recipients with BVKN have poorer graft function. Although active surveillance for BKV has been shown to be effective in reducing incidence of BKVN, it should be tailored specifically to that transplant centre based on its epidemiology and outcomes of BKVN, particularly in centres with limited resources.

Antibodies to BK virus in children prior to allogeneic hematopoietic cell transplant

PubMed Central

Laskin, Benjamin L; Sullivan, Kathleen E; Hester, Jeff; Goebel, Jens; Davies, Stella M; Jodele, Sonata

2015-01-01

BK virus (BKV) is associated with kidney and bladder disease after hematopoietic cell transplantation (HCT) but less is known about the seroprevalence of pre-transplant antibodies to BKV in children. We measured BKV IgG antibody titers in 36 children before HCT. BKV IgG antibodies were detected in all 36 patients, with 28/36 (77.8%) developing BK viremia in the first 100 days. Pre-HCT BKV IgG antibody titers >1:40,960 were protective against later BK viremia ≥10,000 copies/mL. The seroprevalence of antibodies to BKV is high in children undergoing HCT and post-transplant BK viremia, which is associated with bladder and kidney injury, is common. PMID:25833296

Knockout of the BK β2 subunit abolishes inactivation of BK currents in mouse adrenal chromaffin cells and results in slow-wave burst activity

PubMed Central

Martinez-Espinosa, Pedro L.; Yang, Chengtao; Gonzalez-Perez, Vivian; Xia, Xiao-Ming

2014-01-01

Rat and mouse adrenal medullary chromaffin cells (CCs) express an inactivating BK current. This inactivation is thought to arise from the assembly of up to four β2 auxiliary subunits (encoded by the kcnmb2 gene) with a tetramer of pore-forming Slo1 α subunits. Although the physiological consequences of inactivation remain unclear, differences in depolarization-evoked firing among CCs have been proposed to arise from the ability of β2 subunits to shift the range of BK channel activation. To investigate the role of BK channels containing β2 subunits, we generated mice in which the gene encoding β2 was deleted (β2 knockout [KO]). Comparison of proteins from wild-type (WT) and β2 KO mice allowed unambiguous demonstration of the presence of β2 subunit in various tissues and its coassembly with the Slo1 α subunit. We compared current properties and cell firing properties of WT and β2 KO CCs in slices and found that β2 KO abolished inactivation, slowed action potential (AP) repolarization, and, during constant current injection, decreased AP firing. These results support the idea that the β2-mediated shift of the BK channel activation range affects repetitive firing and AP properties. Unexpectedly, CCs from β2 KO mice show an increased tendency toward spontaneous burst firing, suggesting that the particular properties of BK channels in the absence of β2 subunits may predispose to burst firing. PMID:25267913

Effect of protein leaking BK-F PMMA-based hemodialysis on plasma pentosidine levels.

PubMed

Tessitore, Nicola; Lapolla, Annunziata; Aricò, Nadia Concetta; Poli, Albino; Gammaro, Linda; Bassi, Antonella; Bedogna, Valeria; Corgnati, Angela; Reitano, Rachele; Fedele, Domenico; Lupo, Antonio

2004-01-01

Advanced glycation end-products (AGEs) are now considered to contribute to the middle molecule toxicity of uremia and, because they are not cleared by conventional low-flux hemodialysis, alternative strategies are needed to improve their removal. In a prospective cross-over trial involving 18 adult chronic hemodialysis subjects, we evaluated the intradialytic removal and the long-term effect on predialysis levels of Protein-bound (PBPe) and Free (FPe) pentosidine by high-pore, protein-leaking BK-F Polymethylmethacrylate-based hemodialysis (BK-F-HD), by comparing it to hemodialysis using low-flux dialyzers (LF-HD). A single BK-F-HD session removed more PBPe, but not FPe, than LF-HD. Long-term BK-F-HD was associated with a significant decrease in pre-dialysis PBPe, FPe, and albumin (17.7 +/- 20.8, 25.3 +/- 17.3 and 8.0 +/- 3.3%, p<0.01) and no change in body mass index and protein catabolic rate, compared to LF-HD. Multiple stepwise regression analysis identified C-reactive Protein (CRP) (standardized beta coefficient=-0.629), pre-dialysis levels in LF-HD (beta=0.452) and dialysis vintage (beta=0.428) as significant determinants of BK-F-induced changes in predialysis PBPe, and predialysis FPe and PBPe levels in LF-HD as significant determinants of BK-F-induced changes in predialysis FPe (beta=0.720 and 0.286, respectively). Our study shows that long-term standard diffusive hemodialysis with BK-F membrane reduces predialysis PBPe and FPe levels by comparison with LF-HD, largely due to a greater intradialytic clearance of PBPe. Serum albumin is also reduced without any associated changes in nutritional status markers. The study also suggests that the effect of BK-F-HD in lowering PBPe levels is modulated by the body burden of pentosidine and is blunted or even lost in the presence of elevated CRP levels.

BK Channels Mediate Synaptic Plasticity Underlying Habituation in Rats.

PubMed

Zaman, Tariq; De Oliveira, Cleusa; Smoka, Mahabba; Narla, Chakravarthi; Poulter, Michael O; Schmid, Susanne

2017-04-26

Habituation is a basic form of implicit learning and represents a sensory filter that is disrupted in autism, schizophrenia, and several other mental disorders. Despite extensive research in the past decades on habituation of startle and other escape responses, the underlying neural mechanisms are still not fully understood. There is evidence from previous studies indicating that BK channels might play a critical role in habituation. We here used a wide array of approaches to test this hypothesis. We show that BK channel activation and subsequent phosphorylation of these channels are essential for synaptic depression presumably underlying startle habituation in rats, using patch-clamp recordings and voltage-sensitive dye imaging in slices. Furthermore, positive modulation of BK channels in vivo can enhance short-term habituation. Although results using different approaches do not always perfectly align, together they provide convincing evidence for a crucial role of BK channel phosphorylation in synaptic depression underlying short-term habituation of startle. We also show that this mechanism can be targeted to enhance short-term habituation and therefore to potentially ameliorate sensory filtering deficits associated with psychiatric disorders. SIGNIFICANCE STATEMENT Short-term habituation is the most fundamental form of implicit learning. Habituation also represents a filter for inundating sensory information, which is disrupted in autism, schizophrenia, and other psychiatric disorders. Habituation has been studied in different organisms and behavioral models and is thought to be caused by synaptic depression in respective pathways. The underlying molecular mechanisms, however, are poorly understood. We here identify, for the first time, a BK channel-dependent molecular synaptic mechanism leading to synaptic depression that is crucial for habituation, and we discuss the significance of our findings for potential treatments enhancing habituation. Copyright © 2017

The prevalence and implications of BK virus replication in non-renal solid organ transplant recipients: A systematic review.

PubMed

Viswesh, Velliyur; Yost, Sarah E; Kaplan, Bruce

2015-07-01

The significance of BK viruria and viremia in non-renal solid organ transplants is poorly understood. A systematic review was performed reviewing the incidence and implications of BK virus replication in non-renal solid organ transplants. Ninety-seven studies were identified, of which 18 including lung, heart, liver and pancreas transplants were included. The overall incidence of BK viruria and viremia was 20% and 3% respectively and 17 cases of BK nephropathy were identified. Heart transplant recipients had a higher overall incidence of BK viremia than other non-renal organ types, and the majority of cases of BK virus-associated nephropathy were in heart transplant recipients. The incidence of BK viremia was significantly lower in non-renal solid organ transplants than that of renal transplant recipients and BK virus-associated nephropathy was rare. BK virus-associated nephropathy may be considered in heart transplant recipients who have unexplained and persistent renal dysfunction not attributable to other causes. Copyright © 2015 Elsevier Inc. All rights reserved.

Downregulation of BK Channel Function and Protein Expression in Coronary Arteriolar Smooth Muscle Cells of Type 2 Diabetic Patients.

PubMed

Lu, Tong; Chai, Qiang; Jiao, Guoqing; Wang, Xiao-Li; Sun, Xiaojing; Furuseth, Jonathan D; Stulak, John M; Daly, Richard C; Greason, Kevin L; Cha, Yong-Mei; Lee, Hon-Chi

2018-05-30

Type 2 diabetes (T2D) is strongly associated with cardiovascular morbidity and mortality in patients. Vascular large conductance Ca2+-activated potassium (BK) channels, composed of four pore-forming α subunits (BK-α) and four regulatory β1 subunits (BK-β1), are densely expressed in coronary arterial smooth muscle cells (SMCs) and play an important role in regulating vascular tone and myocardial perfusion. However, the role of BK channels in coronary microvascular dysfunction of human subjects with diabetes is unclear. In this study, we examined BK channel function and protein expression, and BK channel-mediated vasodilation in freshly isolated coronary arterioles from T2D patients. Atrial tissues were obtained from 25 patients with T2D and 16 matched non-diabetic subjects during cardiopulmonary bypass procedure. Microvessel videomicroscopy and immunoblot analysis were performed in freshly dissected coronary arterioles and inside-out single BK channel currents was recorded in enzymatically isolated coronary arteriolar SMCs. We found that BK channel sensitivity to physiological Ca2+ concentration and voltage was downregulated in the coronary arteriolar SMCs of diabetic patients, compared with non-diabetic controls. BK channel kinetics analysis revealed that there was significant shortening of the mean open time and prolongation of the mean closed time in diabetic patients, resulting in a remarkable reduction of the channel open probability. Functional studies showed that BK channel activation by dehydrosoyasaponin-1 was diminished and that BK channel-mediated vasodilation in response to shear stress was impaired in diabetic coronary arterioles. Immunoblot experiments confirmed that the protein expressions of BK-α and BK-β1 subunits were significantly downregulated, but the ratio of BK-α/BK-β1 was unchanged in the coronary arterioles of T2D patients. Our results demonstrated for the first time that BK channel function and BK channel-mediated vasodilation were

Molecular mapping of qBK1 WD , a major QTL for bakanae disease resistance in rice.

PubMed

Lee, Sais-Beul; Hur, Yeon-Jae; Cho, Jun-Hyeon; Lee, Jong-Hee; Kim, Tae-Heon; Cho, Soo-Min; Song, You-Chun; Seo, Young-Su; Lee, Jungkwan; Kim, Tae-Sung; Park, Yong-Jin; Oh, Myung-Kyu; Park, Dong-Soo

2018-01-10

Bakanae or foot rot disease is a prominent disease of rice caused by Gibberella fujikuroi. This disease may infect rice plants from the pre-emergence stage to the mature stage. In recent years, raising rice seedlings in seed boxes for mechanical transplanting has increased the incidence of many seedling diseases; only a few rice varieties have been reported to exhibit resistance to bakanae disease. In this study, we attempted to identify quantitative trait loci (QTLs) conferring bakanae disease resistance from the highly resistant japonica variety Wonseadaesoo. A primary QTL study using the genotypes/phenotypes of the recombinant inbred lines (RILs) indicated that the locus qBK1 WD conferring resistance to bakanae disease from Wonseadaesoo was located in a 1.59 Mb interval delimited on the physical map between chr01_13542347 (13.54 Mb) and chr01_15132528 (15.13 Mb). The log of odds (LOD) score of qBK1 WD was 8.29, accounting for 20.2% of the total phenotypic variation. We further identified a gene pyramiding effect of two QTLs, qBK WD and previously developed qBK1. The mean proportion of healthy plant for 31 F 4 RILs that had no resistance genes was 35.3%, which was similar to that of the susceptible check variety Ilpum. The proportion of healthy plants for the lines with only qBK WD or qBK1 was 66.1% and 55.5%, respectively, which was significantly higher than that of the lines without resistance genes and that of Ilpum. The mean proportion of the healthy plant for 15 F 4 RILs harboring both qBK WD and qBK1 was 80.2%, which was significantly higher than that of the lines with only qBK WD or qBK1. Introducing qBK WD or pyramiding the QTLs qBK WD and qBK1 could provide effective tools for breeding rice with bakanae disease resistance. To our knowledge, this is the first report on a gene pyramiding effect that provides higher resistance against bakanae disease.

Big Potassium (BK) ion channels in biology, disease and possible targets for cancer immunotherapy

PubMed Central

Ge, Lisheng; Hoa, Neil T.; Wilson, Zechariah; Arismendi-Morillo, Gabriel; Kong, Xia-Tang; Tajhya, Rajeev B.; Beeton, Christine; Jadus, Martin R.

2017-01-01

The Big Potassium (BK) ion channel is commonly known by a variety of names (Maxi-K, KCNMA1, slo, Stretch-activated potassium channels, KCa1.1). Each name reflects a different physical property displayed by this single ion channel. This transmembrane channel is found on nearly every cell type of the body and has its own distinctive roles for that tissue type. The BKα channel contains the pore that releases potassium ions from intracellular stores. This ion channel is found on the cell membrane, endoplasmic reticulum, Golgi and mitochondria. Complex splicing pathways produce different isoforms. The BKα channels can be phosphorylated, palmitoylated and myristylated. BK is composed of a homo-tetramer that interacts with β and γ chains. These accessory proteins provide a further modulating effect on the functions of BKα channels. BK channels play important roles in cell division and migration. In this review, we will focus on the biology of BK channels, especially its role, and that it has in the immune response towards cancer. Recent proteomic studies have linked BK channels with various proteins. Some of these interactions offer further insight into the role that BK channels have with cancers, especially with brain tumors. This review shows that BK channels have a complex interplay with intracellular components of cancer cells and still have plenty of secrets to be discovered. PMID:25027630

BK virus-associated hemorrhagic cystitis in pediatric cancer patients receiving high-dose cyclophosphamide.

PubMed

Cheerva, Alexandra C; Raj, Ashok; Bertolone, Salvatore J; Bertolone, Kathy; Silverman, Craig L

2007-09-01

Hemorrhagic cystitis (HC) is a known complication of oxazophosphorine chemotherapy. BK virus (BKV) has been commonly found to be associated with hematuria in stem cell transplant patients; however, it has rarely been reported after cyclophosphamide chemotherapy alone. The authors present 3 cases of BK viruria with HC in nontransplant pediatric oncology patients. The 3 patients with BKV had more prolonged hematuria (14 to 16 wk) compared with 1 patient with BKV-negative HC (10 wk). The HC necessitated chemotherapy delays and also prolonged supportive care. One patient was treated with intravenous cidofovir with resolution of BK viruria and hematuria. BKV may have an association with the development of HC in nonstem cell transplant patients receiving high-dose oxazophosphorine chemotherapy. HC may present early and be more prolonged in patients with BK viruria. Patients with HC after cyclophosphamide or ifosfamide with negative bacterial cultures should be studied for BKV. Cidofovir may be beneficial in certain patients with BK viruria and HC; however, definitive data will require a clinical trial.

Nuclear BK Channels Regulate Gene Expression via the Control of Nuclear Calcium Signaling

PubMed Central

Li, Boxing; Jie, Wei; Huang, Lianyan; Wei, Peng; Li, Shuji; Luo, Zhengyi; Friedman, Allyson K.; Meredith, Andrea L.; Han, Ming-Hu; Zhu, Xin-Hong; Gao, Tian-Ming

2014-01-01

Ion channels are essential for the regulation of neuronal functions. The significance of plasma membrane, mitochondrial, endoplasmic reticulum, and lysosomal ion channels in the regulation of Ca2+ is well established. In contrast, surprisingly less is known about the function of ion channels on the nuclear envelope (NE). Here we demonstrate the presence of functional large-conductance, calcium-activated potassium channels (BK channels) on the NE of rodent hippocampal neurons. Functionally blockade of nuclear BK channels (nBK channels) induces NE-derived Ca2+ release, nucleoplasmic Ca2+ elevation, and cAMP response element binding protein (CREB)-dependent transcription. More importantly, blockade of nBK channels regulates nuclear Ca2+-sensitive gene expression and promotes dendritic arborization in a nuclear Ca2+-dependent manner. These results suggest that nBK channel functions as a molecular linker between neuronal activity and nuclear Ca2+ to convey the signals from synapse to nucleus and is a new modulator for synaptic activity-dependent neuronal functions at the NE level. PMID:24952642

Management of BK virus nephropathy in kidney transplant recipients at the Royal Hospital - Clinical Audit - Oman.

PubMed

Al-Raisi, Fatma; Mohsin, Nabil; Kamble, Pramod

2015-04-01

Nephropathy from BK virus (BKV) infection is a growing challenge in kidney transplant recipients globally. It is the result of contemporary potent immunosuppressives aimed at reducing acute rejection and improving allograft survival. Untreated BK virus infections lead to kidney allograft dysfunction or loss. Decreased immunosuppression is the principle treatment but predisposes to acute and chronic rejection. Screening for early detection and prevention of symptomatic BK virus nephropathy may improve outcomes. Although no approved antiviral drug is available, leflunomide, cidofovir, quinolones, and intravenous immunoglobulin have been used. Since the introduction of the new immunosuppressive agents in the transplant regimen at the Royal Hospital, Few cases of BK virus have been detected, and the challenge was to decide upon the best treatment option. The audit was carried out at the Royal Hospital-Oman between January 2010 and December 2012. The nephrology consultant and the clinical pharmacist reviewed all the BK cases and the Royal Hospital. Extensive literature review carried out by the pharmacist to look into the prevalence, prognosis and treatment of BK nephropathy. A treatment protocol was prepared by the clinical pharmacist through guidance of the consultant and was peer reviewed by team of clinical pharmacists and nephrology doctors and approved by the consultant. The audit included 19 patients with positive BK virus ployoma nephropathy. The treatment options were applied stepwise in all the patients with BK virus nephropathy with success rate more than 70%. BK virus nephropathy is emerging at an alarming rate and requires increasing awareness. The uses of current treatment options are still questionable. Our audit confirms that reducing immunosuppression appears to be the criterian standard for the treatment of BK nephropathy.

Pharmacological consequences of the coexpression of BK channel α and auxiliary β subunits

PubMed Central

Torres, Yolima P.; Granados, Sara T.; Latorre, Ramón

2014-01-01

Coded by a single gene (Slo1, KCM) and activated by depolarizing potentials and by a rise in intracellular Ca2+ concentration, the large conductance voltage- and Ca2+-activated K+ channel (BK) is unique among the superfamily of K+ channels. BK channels are tetramers characterized by a pore-forming α subunit containing seven transmembrane segments (instead of the six found in voltage-dependent K+ channels) and a large C terminus composed of two regulators of K+ conductance domains (RCK domains), where the Ca2+-binding sites reside. BK channels can be associated with accessory β subunits and, although different BK modulatory mechanisms have been described, greater interest has recently been placed on the role that the β subunits may play in the modulation of BK channel gating due to its physiological importance. Four β subunits have currently been identified (i.e., β1, β2, β3, and β4) and despite the fact that they all share the same topology, it has been shown that every β subunit has a specific tissue distribution and that they modify channel kinetics as well as their pharmacological properties and the apparent Ca2+ sensitivity of the α subunit in different ways. Additionally, different studies have shown that natural, endogenous, and synthetic compounds can modulate BK channels through β subunits. Considering the importance of these channels in different pathological conditions, such as hypertension and neurological disorders, this review focuses on the mechanisms by which these compounds modulate the biophysical properties of BK channels through the regulation of β subunits, as well as their potential therapeutic uses for diseases such as those mentioned above. PMID:25346693

Pharmacological consequences of the coexpression of BK channel α and auxiliary β subunits.

PubMed

Torres, Yolima P; Granados, Sara T; Latorre, Ramón

2014-01-01

Coded by a single gene (Slo1, KCM) and activated by depolarizing potentials and by a rise in intracellular Ca(2+) concentration, the large conductance voltage- and Ca(2+)-activated K(+) channel (BK) is unique among the superfamily of K(+) channels. BK channels are tetramers characterized by a pore-forming α subunit containing seven transmembrane segments (instead of the six found in voltage-dependent K(+) channels) and a large C terminus composed of two regulators of K(+) conductance domains (RCK domains), where the Ca(2+)-binding sites reside. BK channels can be associated with accessory β subunits and, although different BK modulatory mechanisms have been described, greater interest has recently been placed on the role that the β subunits may play in the modulation of BK channel gating due to its physiological importance. Four β subunits have currently been identified (i.e., β1, β2, β3, and β4) and despite the fact that they all share the same topology, it has been shown that every β subunit has a specific tissue distribution and that they modify channel kinetics as well as their pharmacological properties and the apparent Ca(2+) sensitivity of the α subunit in different ways. Additionally, different studies have shown that natural, endogenous, and synthetic compounds can modulate BK channels through β subunits. Considering the importance of these channels in different pathological conditions, such as hypertension and neurological disorders, this review focuses on the mechanisms by which these compounds modulate the biophysical properties of BK channels through the regulation of β subunits, as well as their potential therapeutic uses for diseases such as those mentioned above.

BK channel β1 subunits regulate airway contraction secondary to M2 muscarinic acetylcholine receptor mediated depolarization.

PubMed

Semenov, Iurii; Wang, Bin; Herlihy, Jeremiah T; Brenner, Robert

2011-04-01

The large conductance calcium- and voltage-activated potassium channel (BK channel) and its smooth muscle-specific β1 subunit regulate excitation–contraction coupling in many types of smooth muscle cells. However, the relative contribution of BK channels to control of M2- or M3-muscarinic acetylcholine receptor mediated airway smooth muscle contraction is poorly understood. Previously, we showed that knockout of the BK channel β1 subunit enhances cholinergic-evoked trachea contractions. Here, we demonstrate that the enhanced contraction of the BK β1 knockout can be ascribed to a defect in BK channel opposition of M2 receptor-mediated contractions. Indeed, the enhanced contraction of β1 knockout is eliminated by specific M2 receptor antagonism. The role of BK β1 to oppose M2 signalling is evidenced by a greater than fourfold increase in the contribution of L-type voltage-dependent calcium channels to contraction that otherwise does not occur with M2 antagonist or with β1 containing BK channels. The mechanism through which BK channels oppose M2-mediated recruitment of calcium channels is through a negative shift in resting voltage that offsets, rather than directly opposes, M2-mediated depolarization. The negative shift in resting voltage is reduced to similar extents by BK β1 knockout or by paxilline block of BK channels. Normalization of β1 knockout baseline voltage with low external potassium eliminated the enhanced M2-receptor mediated contraction. In summary, these findings indicate that an important function of BK/β1 channels is to oppose cholinergic M2 receptor-mediated depolarization and activation of calcium channels by restricting excitation–contraction coupling to more negative voltage ranges.

Genotyping of polyomavirus BK by Real Time PCR for VP1 gene.

PubMed

Gambarino, Stefano; Costa, Cristina; Astegiano, Sara; Piasentin, Elsa Alessio; Segoloni, Giuseppe P; Cavallo, Rossana; Bergallo, Massimiliano

2011-10-01

Polyomavirus BK latently persist in different sites, including the renourinary tract, and may reactivate causing nephropathy in renal transplant recipients or hemorrhagic cystitis in bone marrow recipients. Based on the sequence of the VP1 gene, four genotypes have been described, corresponding to the four serologically differentiated subtypes I-IV, with different prevalence and geographic distribution. In this study, the development and clinical validation of four different Real-Time PCR assays for the detection and discrimination of BKV genotypes as a substitute of DNA sequencing are described. 379 BK VP1 sequences, belonging to the main four genotypes, were aligned and "hot spots" of mutation specific for all the strains or isolates were identified. Specific primers and probes for the detection and discrimination of each genotype by four Real-Time PCR assays were designed and technically validated. Subsequently, the four Real-Time PCR assays were used to test 20 BK-positive urine specimens from renal transplant patients, and evidenced a prevalence of BK genotype I, as previously reported in Europe. Results were confirmed by sequencing. The availability of a rapid and simple genotyping method could be useful for the evaluation of BK genotypes prevalence and studies on the impact of the infecting genotype on viral biological behavior, pathogenic role, and immune evasion strategies.

Cadmium-cysteine coordination in the BK inner pore region and its structural and functional implications.

PubMed

Zhou, Yu; Xia, Xiao-Ming; Lingle, Christopher J

2015-04-21

To probe structure and gating-associated conformational changes in BK-type potassium (BK) channels, we examined consequences of Cd(2+) coordination with cysteines introduced at two positions in the BK inner pore. At V319C, the equivalent of valine in the conserved Kv proline-valine-proline (PVP) motif, Cd(2+) forms intrasubunit coordination with a native glutamate E321, which would place the side chains of V319C and E321 much closer together than observed in voltage-dependent K(+) (Kv) channel structures, requiring that the proline between V319C and E321 introduces a kink in the BK S6 inner helix sharper than that observed in Kv channel structures. At inner pore position A316C, Cd(2+) binds with modest state dependence, suggesting the absence of an ion permeation gate at the cytosolic side of BK channel. These results highlight fundamental structural differences between BK and Kv channels in their inner pore region, which likely underlie differences in voltage-dependent gating between these channels.

BK channel β1 subunits regulate airway contraction secondary to M2 muscarinic acetylcholine receptor mediated depolarization

PubMed Central

Semenov, Iurii; Wang, Bin; Herlihy, Jeremiah T; Brenner, Robert

2011-01-01

Abstract The large conductance calcium- and voltage-activated potassium channel (BK channel) and its smooth muscle-specific β1 subunit regulate excitation–contraction coupling in many types of smooth muscle cells. However, the relative contribution of BK channels to control of M2- or M3-muscarinic acetylcholine receptor mediated airway smooth muscle contraction is poorly understood. Previously, we showed that knockout of the BK channel β1 subunit enhances cholinergic-evoked trachea contractions. Here, we demonstrate that the enhanced contraction of the BK β1 knockout can be ascribed to a defect in BK channel opposition of M2 receptor-mediated contractions. Indeed, the enhanced contraction of β1 knockout is eliminated by specific M2 receptor antagonism. The role of BK β1 to oppose M2 signalling is evidenced by a greater than fourfold increase in the contribution of L-type voltage-dependent calcium channels to contraction that otherwise does not occur with M2 antagonist or with β1 containing BK channels. The mechanism through which BK channels oppose M2-mediated recruitment of calcium channels is through a negative shift in resting voltage that offsets, rather than directly opposes, M2-mediated depolarization. The negative shift in resting voltage is reduced to similar extents by BK β1 knockout or by paxilline block of BK channels. Normalization of β1 knockout baseline voltage with low external potassium eliminated the enhanced M2-receptor mediated contraction. In summary, these findings indicate that an important function of BK/β1 channels is to oppose cholinergic M2 receptor-mediated depolarization and activation of calcium channels by restricting excitation–contraction coupling to more negative voltage ranges. PMID:21300746

Review article: BK virus in systemic lupus erythematosus.

PubMed

Gupta, Nirupama; Lawrence, Robert M; Nguyen, Cuong; Modica, Renee F

2015-08-21

BK virus (BKV) is a human polyomavirus with a seroprevalence of 60-80 % in the general population. In renal transplant patients, it is known to cause renal failure, ureteric stenosis and hemorrhagic cystitis. In bone marrow transplant patients, it is evident that BKV can also cause hemorrhagic cystitis along with BK virus nephropathy (BKVN) in the native kidneys, with subsequent renal failure. However, little is known about BVKN in non-transplanted immune-compromised patients, such as systemic lupus erythematosus (SLE) who may have underlying nephritis and have a compromised immune system due to therapy and/or systemic illness. Thus, this article will focus on the clinical aspects of BKV and its association in patients with SLE.

Effect of aldosterone on BK channel expression in mammalian cortical collecting duct

PubMed Central

Estilo, Genevieve; Liu, Wen; Pastor-Soler, Nuria; Mitchell, Phillip; Carattino, Marcelo D.; Kleyman, Thomas R.; Satlin, Lisa M.

2008-01-01

Apical large-conductance Ca2+-activated K+ (BK) channels in the cortical collecting duct (CCD) mediate flow-stimulated K+ secretion. Dietary K+ loading for 10–14 days leads to an increase in BK channel mRNA abundance, enhanced flow-stimulated K+ secretion in microperfused CCDs, and a redistribution of immunodetectable channels from an intracellular pool to the apical membrane (Najjar F, Zhou H, Morimoto T, Bruns JB, Li HS, Liu W, Kleyman TR, Satlin LM. Am J Physiol Renal Physiol 289: F922–F932, 2005). To test whether this adaptation was mediated by a K+-induced increase in aldosterone, New Zealand White rabbits were fed a low-Na+ (LS) or high-Na+ (HS) diet for 7–10 days to alter circulating levels of aldosterone but not serum K+ concentration. Single CCDs were isolated for quantitation of BK channel subunit (total, α-splice variants, β-isoforms) mRNA abundance by real-time PCR and measurement of net transepithelial Na+ (JNa) and K+ (JK) transport by microperfusion; kidneys were processed for immunolocalization of BK α-subunit by immunofluorescence microscopy. At the time of death, LS rabbits excreted no urinary Na+ and had higher circulating levels of aldosterone than HS animals. The relative abundance of BK α-, β2-, and β4-subunit mRNA and localization of immunodetectable α-subunit were similar in CCDs from LS and HS animals. In response to an increase in tubular flow rate from ∼1 to 5 nl·min−1·mm−1, the increase in JNa was greater in LS vs. HS rabbits, yet the flow-stimulated increase in JK was similar in both groups. These data suggest that aldosterone does not contribute to the regulation of BK channel expression/activity in response to dietary K+ loading. PMID:18579708

Vertebrate rod photoreceptors express both BK and IK calcium-activated potassium channels, but only BK channels are involved in receptor potential regulation.

PubMed

Pelucchi, Bruna; Grimaldi, Annalisa; Moriondo, Andrea

2008-01-01

In salamander rods, Ca(2+)-activated K(+) current (I(KCa)) provides an effective "clamp" of the dark membrane potential to its normal resting level. By a combination of electrophysiological, pharmacological, and immunohistochemical approaches, we show that salamander rods functionally express large-conductance Ca(2+)- and voltage-dependent potassium (BK) channel and intermediate-conductance Ca(2+)-dependent potassium (IK) channel, but not small-conductance Ca(2+)-dependent potassium channel (SK) subtypes. Application of 100 nM iberiotoxin and 100 nM clotrimazole reduced net I(KCa) to 36% and 63%, respectively, whereas the current was unaffected by application of 1 microM apamin. Consistently, anti- SK1, -SK2, and -SK3 antibodies were unable to stain rod photoreceptors, whereas both anti-BK and -SK4/ IK1 antibodies heavily stained the ellipsoid region of the inner segments of the rods. Moreover, by using current-clamp experiments, it was clearly seen that the strong clamping effect of the total I(KCa) was lost when IbTx, but not CLTZ, was applied to the bath. This behavior strongly suggests that of BK and IK channels, only the former are responsible for the clamping effect on the photoreceptor membrane potential.

Efficacy of Levofloxacin in the Treatment of BK Viremia: A Multicenter, Double-Blinded, Randomized, Placebo-Controlled Trial

PubMed Central

Lee, Belinda T.; Gabardi, Steven; Grafals, Monica; Hofmann, R. Michael; Akalin, Enver; Aljanabi, Aws; Mandelbrot, Didier A.; Adey, Deborah B.; Heher, Eliot; Fan, Pang-Yen; Conte, Sarah; Dyer-Ward, Christine

2014-01-01

Background and objectives BK virus reactivation in kidney transplant recipients can lead to progressive allograft injury. Reduction of immunosuppression remains the cornerstone of treatment for active BK infection. Fluoroquinolone antibiotics are known to have in vitro antiviral properties, but the evidence for their use in patients with BK viremia is inconclusive. The objective of the study was to determine the efficacy of levofloxacin in the treatment of BK viremia. Design, setting, participants, & measurements Enrollment in this prospective, multicenter, double-blinded, placebo-controlled trial occurred from July 2009 to March 2012. Thirty-nine kidney transplant recipients with BK viremia were randomly assigned to receive levofloxacin, 500 mg daily, or placebo for 30 days. Immunosuppression in all patients was adjusted on the basis of standard clinical practices at each institution. Plasma BK viral load and serum creatinine were measured monthly for 3 months and at 6 months. Results At the 3-month follow-up, the percentage reductions in BK viral load were 70.3% and 69.1% in the levofloxacin group and the placebo group, respectively (P=0.93). The percentage reductions in BK viral load were also equivalent at 1 month (58% versus and 67.1%; P=0.47) and 6 months (82.1% versus 90.5%; P=0.38). Linear regression analysis of serum creatinine versus time showed no difference in allograft function between the two study groups during the follow-up period. Conclusions A 30-day course of levofloxacin does not significantly improve BK viral load reduction or allograft function when used in addition to overall reduction of immunosuppression. PMID:24482066

Efficacy of levofloxacin in the treatment of BK viremia: a multicenter, double-blinded, randomized, placebo-controlled trial.

PubMed

Lee, Belinda T; Gabardi, Steven; Grafals, Monica; Hofmann, R Michael; Akalin, Enver; Aljanabi, Aws; Mandelbrot, Didier A; Adey, Deborah B; Heher, Eliot; Fan, Pang-Yen; Conte, Sarah; Dyer-Ward, Christine; Chandraker, Anil

2014-03-01

BK virus reactivation in kidney transplant recipients can lead to progressive allograft injury. Reduction of immunosuppression remains the cornerstone of treatment for active BK infection. Fluoroquinolone antibiotics are known to have in vitro antiviral properties, but the evidence for their use in patients with BK viremia is inconclusive. The objective of the study was to determine the efficacy of levofloxacin in the treatment of BK viremia. Enrollment in this prospective, multicenter, double-blinded, placebo-controlled trial occurred from July 2009 to March 2012. Thirty-nine kidney transplant recipients with BK viremia were randomly assigned to receive levofloxacin, 500 mg daily, or placebo for 30 days. Immunosuppression in all patients was adjusted on the basis of standard clinical practices at each institution. Plasma BK viral load and serum creatinine were measured monthly for 3 months and at 6 months. At the 3-month follow-up, the percentage reductions in BK viral load were 70.3% and 69.1% in the levofloxacin group and the placebo group, respectively (P=0.93). The percentage reductions in BK viral load were also equivalent at 1 month (58% versus and 67.1%; P=0.47) and 6 months (82.1% versus 90.5%; P=0.38). Linear regression analysis of serum creatinine versus time showed no difference in allograft function between the two study groups during the follow-up period. A 30-day course of levofloxacin does not significantly improve BK viral load reduction or allograft function when used in addition to overall reduction of immunosuppression.

Long-term hypoxia increases calcium affinity of BK channels in ovine fetal and adult cerebral artery smooth muscle

PubMed Central

Tao, Xiaoxiao; Lin, Mike T.; Thorington, Glyne U.; Wilson, Sean M.; Longo, Lawrence D.

2015-01-01

Acclimatization to high-altitude, long-term hypoxia (LTH) reportedly alters cerebral artery contraction-relaxation responses associated with changes in K+ channel activity. We hypothesized that to maintain oxygenation during LTH, basilar arteries (BA) in the ovine adult and near-term fetus would show increased large-conductance Ca2+ activated potassium (BK) channel activity. We measured BK channel activity, expression, and cell surface distribution by use of patch-clamp electrophysiology, flow cytometry, and confocal microscopy, respectively, in myocytes from normoxic control and LTH adult and near-term fetus BA. Electrophysiological data showed that BK channels in LTH myocytes exhibited 1) lowered Ca2+ set points, 2) left-shifted activation voltages, and 3) longer dwell times. BK channels in LTH myocytes also appeared to be more dephosphorylated. These differences collectively make LTH BK channels more sensitive to activation. Studies using flow cytometry showed that the LTH fetus exhibited increased BK β1 subunit surface expression. In addition, in both fetal groups confocal microscopy revealed increased BK channel clustering and colocalization to myocyte lipid rafts. We conclude that increased BK channel activity in LTH BA occurred in association with increased channel affinity for Ca2+ and left-shifted voltage activation. Increased cerebrovascular BK channel activity may be a mechanism by which LTH adult and near-term fetal sheep can acclimatize to long-term high altitude hypoxia. Our findings suggest that increasing BK channel activity in cerebral myocytes may be a therapeutic target to ameliorate the adverse effects of high altitude in adults or of intrauterine hypoxia in the fetus. PMID:25599571

Low Na, High K Diet and the Role of Aldosterone in BK-Mediated K Excretion

PubMed Central

Cornelius, Ryan J.; Wen, Donghai; Li, Huaqing; Yuan, Yang; Wang-France, Jun; Warner, Paige C.; Sansom, Steven C.

2015-01-01

A low Na, high K diet (LNaHK) is associated with a low rate of cardiovascular (CV) disease in many societies. Part of the benefit of LNaHK relies on its diuretic effects; however, the role of aldosterone (aldo) in the diuresis is not understood. LNaHK mice exhibit an increase in renal K secretion that is dependent on the large, Ca-activated K channel, (BK-α with accessory BK-β4; BK-α/β4). We hypothesized that aldo causes an osmotic diuresis by increasing BK-α/β4-mediated K secretion in LNaHK mice. We found that the plasma aldo concentration (P[aldo]) was elevated by 10-fold in LNaHK mice compared with control diet (Con) mice. We subjected LNaHK mice to either sham surgery (sham), adrenalectomy (ADX) with low aldo replacement (ADX-LA), or ADX with high aldo replacement (ADX-HA). Compared to sham, the urinary flow, K excretion rate, transtubular K gradient (TTKG), and BK-α and BK-β4 expressions, were decreased in ADX-LA, but not different in ADX-HA. BK-β4 knockout (β4KO) and WT mice exhibited similar K clearance and TTKG in the ADX-LA groups; however, in sham and ADX-HA, the K clearance and TTKG of β4KO were less than WT. In response to amiloride treatment, the osmolar clearance was increased in WT Con, decreased in WT LNaHK, and unchanged in β4KO LNaHK. These data show that the high P[aldo] of LNaHK mice is necessary to generate a high rate of BK-α/β4-mediated K secretion, which creates an osmotic diuresis that may contribute to a reduction in CV disease. PMID:25607984

Diagnosis of BK viral nephropathy in the renal allograft biopsy: role of fluorescence in situ hybridization.

PubMed

Wang, Zhen; Portier, Bryce P; Hu, Bo; Chiesa-Vottero, Andres; Myles, Jonathan; Procop, Gary W; Tubbs, Raymond R

2012-09-01

Early recognition of BK viral nephropathy is essential for successful management. Our aim in this study was to evaluate a novel fluorescence in situ hybridization (FISH) assay for detection of BK virus in renal transplant biopsies in the context of standard detection methods. Renal allograft biopsies (n = 108) were analyzed via H&E, immunohistochemistry (IHC) for simian virus 40, and FISH for BK virus. BK virus was detected in 16 (14.8%) cases by H&E, 13 (12%) cases by IHC, 18 (16.6%) cases by FISH, and 19 (17.6%) cases by real-time PCR; 24 of 108 showed a discrepancy in ≥1 testing modalities. Comparison of H&E, IHC, and FISH showed no statistical difference in detection of BK virus. However, performing comparisons between the different tissue-based assays in the context of plasma or urine real-time PCR results showed significant improvement in detection of BK by FISH over H&E (P = 0.02) but not IHC (P = 0.07). This novel FISH-based approach for BK virus identification in renal allograft biopsy tissue mirrored real-time PCR results and showed superior performance to detection of inclusions by H&E. Therefore, use of FISH for BK virus detection in the setting of renal allograft biopsy is a useful and sensitive detection method and could be adopted in any laboratory that currently performs FISH analysis. Copyright © 2012 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.

Identification of pyrolysis products of the new psychoactive substance 2-amino-1-(4-bromo-2,5-dimethoxyphenyl)ethanone hydrochloride (bk-2C-B) and its iodo analogue bk-2C-I.

PubMed

Texter, Kelly B; Waymach, Rachel; Kavanagh, Pierce V; O'Brien, John E; Talbot, Brian; Brandt, Simon D; Gardner, Elizabeth A

2018-01-01

2-Amino-1-(4-bromo-2,5-dimethoxyphenyl)ethanone hydrochloride (bk-2C-B) has recently emerged as a new psychoactive substance (NPS). It is most commonly consumed orally, although there are indications that it might also be ingested by inhalation or 'smoking'. Information about the stability of bk-2C-B when exposed to heat is unavailable and the potential for pyrolytic degradation and formation of unknown substances available for inhalation prompted an investigation using a simulated 'meth pipe' scenario. Twelve products following pyrolysis of bk-2C-B were detected and verified by organic synthesis of the corresponding standards. In addition, 2-amino-1-(4-iodo-2,5-dimethoxyphenyl)ethanone hydrochloride (bk-2C-I) was characterized for the first time and subjected to pyrolysis as well. Similar products were formed, which indicated that the replacement of the bromo with the iodo substituent did not affect the pyrolysis pattern under the conditions used. Two additional products were detected in the bk-2C-I pyrolates, namely 1-(2,5-dimethoxyphenyl)-ethanone and 1-iodo-4-ethenyl-5-methoxyphenol. The potential ingestion of pyrolysis products with unknown toxicity adds an element of concern. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Time-resolved resonance Raman spectroscopy of intermediates of bacteriorhodopsin: The bK(590) intermediate.

PubMed

Terner, J; Hsieh, C L; Burns, A R; El-Sayed, M A

1979-07-01

We have combined microbeam and flow techniques with computer subtraction methods to obtain the resonance Raman spectrum of the short lived batho-intermediate (bK(590)) of bacteriorhodopsin. Comparison of the spectra obtained in (1)H(2)O and (2)H(2)O, as well as the fact that the bK(590) intermediate shows large optical red shifts, suggests that the Schiff base linkage of this intermediate is protonated. The fingerprint region of the spectrum of bK(590), sensitive to the isomeric configuration of the retinal chromophore, does not resemble the corresponding region of the parent bR(570) form. The resonance Raman spectrum of bK(590) as well as the spectra of all of the other main intermediates in the photoreaction cycle of bacteriorhodopsin are discussed and compared with resonance Raman spectra of published model compounds.

Conopeptide Vt3.1 preferentially inhibits BK potassium channels containing β4 subunits via electrostatic interactions.

PubMed

Li, Min; Chang, Shan; Yang, Longjin; Shi, Jingyi; McFarland, Kelli; Yang, Xiao; Moller, Alyssa; Wang, Chunguang; Zou, Xiaoqin; Chi, Chengwu; Cui, Jianmin

2014-02-21

BK channel β subunits (β1-β4) modulate the function of channels formed by slo1 subunits to produce tissue-specific phenotypes. The molecular mechanism of how the homologous β subunits differentially alter BK channel functions and the role of different BK channel functions in various physiologic processes remain unclear. By studying channels expressed in Xenopus laevis oocytes, we show a novel disulfide-cross-linked dimer conopeptide, Vt3.1 that preferentially inhibits BK channels containing the β4 subunit, which is most abundantly expressed in brain and important for neuronal functions. Vt3.1 inhibits the currents by a maximum of 71%, shifts the G-V relation by 45 mV approximately half-saturation concentrations, and alters both open and closed time of single channel activities, indicating that the toxin alters voltage dependence of the channel. Vt3.1 contains basic residues and inhibits voltage-dependent activation by electrostatic interactions with acidic residues in the extracellular loops of the slo1 and β4 subunits. These results suggest a large interaction surface between the slo1 subunit of BK channels and the β4 subunit, providing structural insight into the molecular interactions between slo1 and β4 subunits. The results also suggest that Vt3.1 is an excellent tool for studying β subunit modulation of BK channels and for understanding the physiological roles of BK channels in neurophysiology.

Molecular mechanism underlying β1 regulation in voltage- and calcium-activated potassium (BK) channels

PubMed Central

Castillo, Karen; Contreras, Gustavo F.; Pupo, Amaury; Torres, Yolima P.; Neely, Alan; González, Carlos; Latorre, Ramon

2015-01-01

Being activated by depolarizing voltages and increases in cytoplasmic Ca2+, voltage- and calcium-activated potassium (BK) channels and their modulatory β-subunits are able to dampen or stop excitatory stimuli in a wide range of cellular types, including both neuronal and nonneuronal tissues. Minimal alterations in BK channel function may contribute to the pathophysiology of several diseases, including hypertension, asthma, cancer, epilepsy, and diabetes. Several gating processes, allosterically coupled to each other, control BK channel activity and are potential targets for regulation by auxiliary β-subunits that are expressed together with the α (BK)-subunit in almost every tissue type where they are found. By measuring gating currents in BK channels coexpressed with chimeras between β1 and β3 or β2 auxiliary subunits, we were able to identify that the cytoplasmic regions of β1 are responsible for the modulation of the voltage sensors. In addition, we narrowed down the structural determinants to the N terminus of β1, which contains two lysine residues (i.e., K3 and K4), which upon substitution virtually abolished the effects of β1 on charge movement. The mechanism by which K3 and K4 stabilize the voltage sensor is not electrostatic but specific, and the α (BK)-residues involved remain to be identified. This is the first report, to our knowledge, where the regulatory effects of the β1-subunit have been clearly assigned to a particular segment, with two pivotal amino acids being responsible for this modulation. PMID:25825713

BK channels are required for multisensory plasticity in the oculomotor system

PubMed Central

Nelson, Alexandra; Faulstich, Michael; Moghadam, Setareh; Onori, Kimberly; Meredith, Andrea; du Lac, Sascha

2017-01-01

SUMMARY Neural circuits are endowed with several forms of intrinsic and synaptic plasticity that could contribute to adaptive changes in behavior, but circuit complexities have hindered linking specific cellular mechanisms with their behavioral consequences. Eye movements generated by simple brainstem circuits provide a means for relating cellular plasticity to behavioral gain control. Here we show that firing rate potentiation, a form of intrinsic plasticity mediated by reductions in BK-type calcium activated potassium currents in spontaneously firing neurons, is engaged during optokinetic reflex compensation for inner ear dysfunction. Vestibular loss triggers transient increases in postsynaptic excitability, occlusion of firing rate potentiation, and reductions in BK currents in vestibular nucleus neurons. Concurrently, adaptive increases in visually-evoked eye movements rapidly restore oculomotor function in wildtype mice but are profoundly impaired in BK channel null mice. Activity-dependent regulation of intrinsic excitability may be a general mechanism for adaptive control of behavioral output in multisensory circuits. PMID:27989457

[The BK virus load in urine in association with the development of hemorrhagic cystitis after hematopoietic stem cell transplantation].

PubMed

Xie, Ying; Han, Yue; Wu, De-pei; Sun, Ai-ning; Cen, Jian-nong; Yao, Li; Ruan, Chang-geng

2009-08-01

To analyze the relationship between BK viruria and the late onset hemorrhagic cystitis (LOHC) after hematopoietic stem cell transplantation (HSCT), and investigate the role of BK virus load in the development of LOHC. From August 2006 to April 2008, urine samples were collected weekly from 113 patients undergoing HSCT. Virus DNA were extracted from the urine samples and amplified by qualitative PCR. Real-time quantitative PCR was used to quantify BKV DNA in the urine samples of all BK viruria patients. LOHC occurred in 22 patients (19.5%), including grade 1 in 7, grade 2 in 11, grade 3 in 3, and grade 4 in one. The median onset time was 44 (13 - 114) days after transplantation. Twenty-one of which (95.5%) were BK virus positive, being significantly higher than that in non-LOHC patients (31.9%) (P = 0.000). No BK virus was detected in the healthy control group at the same time. Quantitative PCR detection showed that the mean BK virus DNA copies in LOHC patients at a week before occurring HC was higher than that at the first positive samples (10(5) copies/microl versus 10(4) copies/microl, P = 0.025), and it was no significant change at the onset and a week after HC. Meanwhile, there was no statistical difference in the mean level of BK virus DNA copies among the LOHC patients with different grades. The mean level of BK virus DNA copies in non-HC patients was 10(3) to 10(4) copies/microl, being lower than that in LOHC patients. BK viruria is an important pathogenic cause of the LOHC after HSCT. The occurrence of BKV viruria in HSCT patients, together with the increasing of BK virus DNA copies in urine, over the level of 10(5) copies/microl may indicate a possible development of LOHC.

Heme Regulates Allosteric Activation of the Slo1 BK Channel

PubMed Central

Horrigan, Frank T.; Heinemann, Stefan H.; Hoshi, Toshinori

2005-01-01

Large conductance calcium-dependent (Slo1 BK) channels are allosterically activated by membrane depolarization and divalent cations, and possess a rich modulatory repertoire. Recently, intracellular heme has been identified as a potent regulator of Slo1 BK channels (Tang, X.D., R. Xu, M.F. Reynolds, M.L. Garcia, S.H. Heinemann, and T. Hoshi. 2003. Nature. 425:531–535). Here we investigated the mechanism of the regulatory action of heme on heterologously expressed Slo1 BK channels by separating the influences of voltage and divalent cations. In the absence of divalent cations, heme generally decreased ionic currents by shifting the channel's G–V curve toward more depolarized voltages and by rendering the curve less steep. In contrast, gating currents remained largely unaffected by heme. Simulations suggest that a decrease in the strength of allosteric coupling between the voltage sensor and the activation gate and a concomitant stabilization of the open state account for the essential features of the heme action in the absence of divalent ions. At saturating levels of divalent cations, heme remained similarly effective with its influence on the G–V simulated by weakening the coupling of both Ca2+ binding and voltage sensor activation to channel opening. The results thus show that heme dampens the influence of allosteric activators on the activation gate of the Slo1 BK channel. To account for these effects, we consider the possibility that heme binding alters the structure of the RCK gating ring and thereby disrupts both Ca2+- and voltage-dependent gating as well as intrinsic stability of the open state. PMID:15955873

S-acylation dependent post-translational cross-talk regulates large conductance calcium- and voltage- activated potassium (BK) channels

PubMed Central

Shipston, Michael J.

2014-01-01

Mechanisms that control surface expression and/or activity of large conductance calcium-activated potassium (BK) channels are important determinants of their (patho)physiological function. Indeed, BK channel dysfunction is associated with major human disorders ranging from epilepsy to hypertension and obesity. S-acylation (S-palmitoylation) represents a major reversible, post-translational modification controlling the properties and function of many proteins including ion channels. Recent evidence reveals that both pore-forming and regulatory subunits of BK channels are S-acylated and control channel trafficking and regulation by AGC-family protein kinases. The pore-forming α-subunit is S-acylated at two distinct sites within the N- and C-terminus, each site being regulated by different palmitoyl acyl transferases (zDHHCs) and acyl thioesterases (APTs). S-acylation of the N-terminus controls channel trafficking and surface expression whereas S-acylation of the C-terminal domain determines regulation of channel activity by AGC-family protein kinases. S-acylation of the regulatory β4-subunit controls ER exit and surface expression of BK channels but does not affect ion channel kinetics at the plasma membrane. Furthermore, a significant number of previously identified BK-channel interacting proteins have been shown, or are predicted to be, S-acylated. Thus, the BK channel multi-molecular signaling complex may be dynamically regulated by this fundamental post-translational modification and thus S-acylation likely represents an important determinant of BK channel physiology in health and disease. PMID:25140154

Bicarbonate promotes BK-α/β4-mediated K excretion in the renal distal nephron

PubMed Central

Cornelius, Ryan J.; Wen, Donghai; Hatcher, Lori I.

2012-01-01

Ca-activated K channels (BK), which are stimulated by high distal nephron flow, are utilized during high-K conditions to remove excess K. Because BK predominantly reside with BK-β4 in acid/base-transporting intercalated cells (IC), we determined whether BK-β4 knockout mice (β4KO) exhibit deficient K excretion when consuming a high-K alkaline diet (HK-alk) vs. high-K chloride diet (HK-Cl). When wild type (WT) were placed on HK-alk, but not HK-Cl, renal BK-β4 expression increased (Western blot). When WT and β4KO were placed on HK-Cl, plasma K concentration ([K]) was elevated compared with control K diets; however, K excretion was not different between WT and β4KO. When HK-alk was consumed, the plasma [K] was lower and K clearance was greater in WT compared with β4KO. The urine was alkaline in mice on HK-alk; however, urinary pH was not different between WT and β4KO. Immunohistochemical analysis of pendrin and V-ATPase revealed the same increases in β-IC, comparing WT and β4KO on HK-alk. We found an amiloride-sensitive reduction in Na excretion in β4KO, compared with WT, on HK-alk, indicating enhanced Na reabsorption as a compensatory mechanism to secrete K. Treating mice with an alkaline, Na-deficient, high-K diet (LNaHK) to minimize Na reabsorption exaggerated the defective K handling of β4KO. When WT on LNaHK were given NH4Cl in the drinking water, K excretion was reduced to the magnitude of β4KO on LNaHK. These results show that WT, but not β4KO, efficiently excretes K on HK-alk but not on HK-Cl and suggest that BK-α/β4-mediated K secretion is promoted by bicarbonaturia. PMID:22993067

Reactive Oxygen Species Signaling Facilitates FOXO-3a/FBXO-Dependent Vascular BK Channel β1 Subunit Degradation in Diabetic Mice

PubMed Central

Lu, Tong; Chai, Qiang; Yu, Ling; d’Uscio, Livius V.; Katusic, Zvonimir S.; He, Tongrong; Lee, Hon-Chi

2012-01-01

Activity of the vascular large conductance Ca2+-activated K+ (BK) channel is tightly regulated by its accessory β1 subunit (BK-β1). Downregulation of BK-β1 expression in diabetic vessels is associated with upregulation of the forkhead box O subfamily transcription factor-3a (FOXO-3a)–dependent F-box–only protein (FBXO) expression. However, the upstream signaling regulating this process is unclear. Overproduction of reactive oxygen species (ROS) is a common finding in diabetic vasculopathy. We hypothesized that ROS signaling cascade facilitates the FOXO-3a/FBXO-mediated BK-β1 degradation and leads to diabetic BK channel dysfunction. Using cellular biology, patch clamp, and videomicroscopy techniques, we found that reduced BK-β1 expression in streptozotocin (STZ)-induced diabetic mouse arteries and in human coronary smooth muscle cells (SMCs) cultured with high glucose was attributable to an increase in protein kinase C (PKC)-β and NADPH oxidase expressions and accompanied by attenuation of Akt phosphorylation and augmentation of atrogin-1 expression. Treatment with ruboxistaurin (a PKCβ inhibitor) or with GW501516 (a peroxisome proliferator–activated receptor δ activator) reduced atrogin-1 expression and restored BK channel-mediated coronary vasodilation in diabetic mice. Our results suggested that oxidative stress inhibited Akt signaling and facilitated the FOXO-3a/FBXO-dependent BK-β1 degradation in diabetic vessels. Suppression of the FOXO-3a/FBXO pathway prevented vascular BK-β1 degradation and protected coronary function in diabetes. PMID:22586590

Evaluating the BK 21 Program. Research Brief

ERIC Educational Resources Information Center

Seong, Somi; Popper, Steven W.; Goldman, Charles A.; Evans, David K.; Grammich, Clifford A.

2008-01-01

The Brain Korea 21 program (BK21), an effort to improve Korean universities and research, has attracted a great deal of attention in Korea, producing the need to understand how well the program is meeting its goals. RAND developed a logic model for identifying program goals and dynamics, suggested quantitative and qualitative evaluation methods,…

Putative calcium-binding domains of the Caenorhabditis elegans BK channel are dispensable for intoxication and ethanol activation

PubMed Central

Davis, S. J.; Scott, L. L.; Ordemann, G.; Philpo, A.; Cohn, J.; Pierce-Shimomura, J. T.

2016-01-01

Alcohol modulates the highly conserved, voltage- and calcium-activated potassium (BK) channel, which contributes to alcohol-mediated behaviors in species from worms to humans. Previous studies have shown that the calcium-sensitive domains, RCK1 and the Ca2+ bowl, are required for ethanol activation of the mammalian BK channel in vitro. In the nematode Caenorhabditis elegans, ethanol activates the BK channel in vivo, and deletion of the worm BK channel, SLO-1, confers strong resistance to intoxication. To determine if the conserved RCK1 and calcium bowl domains were also critical for intoxication and basal BK channel-dependent behaviors in C. elegans, we generated transgenic worms that express mutated SLO-1 channels predicted to have the RCK1, Ca2+ bowl or both domains rendered insensitive to calcium. As expected, mutating these domains inhibited basal function of SLO-1 in vivo as neck and body curvature of these mutants mimicked that of the BK null mutant. Unexpectedly, however, mutating these domains singly or together in SLO-1 had no effect on intoxication in C. elegans. Consistent with these behavioral results, we found that ethanol activated the SLO-1 channel in vitro with or without these domains. By contrast, in agreement with previous in vitro findings, C. elegans harboring a human BK channel with mutated calcium-sensing domains displayed resistance to intoxication. Thus, for the worm SLO-1 channel, the putative calcium-sensitive domains are critical for basal in vivo function but unnecessary for in vivo ethanol action. PMID:26113050

Intermediate-dose cidofovir without probenecid in the treatment of BK virus allograft nephropathy.

PubMed

Araya, Carlos E; Lew, Judy F; Fennell, Robert S; Neiberger, Richard E; Dharnidharka, Vikas R

2006-02-01

BK virus allograft nephropathy (BKVAN) is a rising complication in kidney transplant recipients. Reducing immunosuppression has been the initial form of therapy in most cases, but is not always associated with improvement in graft function. Anti-viral therapy with low-dose cidofovir (0.25-0.42 mg/kg/dose) has been used successfully in some patients, but dose-related nephrotoxicity has limited its use. We present our experience with 3 kidney transplant recipients diagnosed with BKVAN who received intermediate-dose cidofovir (0.75-1.0 mg/kg/dose) without probenecid, and without concomitant nephrotoxicity. Three female patients, ages 8, 19 and 20 yr, presented with elevated serum creatinine (SCr) values, BK virus stain positive on renal biopsy and high plasma BK viral loads. As a result of viral loads being >2 million copies/ml in two patients and a lack of response to reduction in immunosuppression in the third, we initiated therapy with low-dose cidofovir. Because of persistent positive BK stain and positive plasma viral load, we then administered intermediate-dose cidofovir, without probenecid, for several subsequent doses (seven to 15 infusions till date). All patients tolerated the intermediate-dose cidofovir with no significant rise in SCr during the course of the infusions. The most recent SCr values in all three patients were improved from those at the initial diagnosis of BKVAN. All three patients showed a marked drop in BK viral loads when on intermediate-dose cidofovir, with complete clearing of viremia in two patients. In our experience, intermediate-dose cidofovir without probenecid, used judiciously, is not associated with additional nephrotoxicity and may provide an additional alternative for treatment.

Alcohol modulation of BK channel gating depends on β subunit composition

PubMed Central

Kuntamallappanavar, Guruprasad

2016-01-01

In most mammalian tissues, Ca2+i/voltage-gated, large conductance K+ (BK) channels consist of channel-forming slo1 and auxiliary (β1–β4) subunits. When Ca2+i (3–20 µM) reaches the vicinity of BK channels and increases their activity at physiological voltages, β1- and β4-containing BK channels are, respectively, inhibited and potentiated by intoxicating levels of ethanol (50 mM). Previous studies using different slo1s, lipid environments, and Ca2+i concentrations—all determinants of the BK response to ethanol—made it impossible to determine the specific contribution of β subunits to ethanol action on BK activity. Furthermore, these studies measured ethanol action on ionic current under a limited range of stimuli, rendering no information on the gating processes targeted by alcohol and their regulation by βs. Here, we used identical experimental conditions to obtain single-channel and macroscopic currents of the same slo1 channel (“cbv1” from rat cerebral artery myocytes) in the presence and absence of 50 mM ethanol. First, we assessed the role five different β subunits (1,2,2-IR, 3-variant d, and 4) in ethanol action on channel function. Thus, two phenotypes were identified: (1) ethanol potentiated cbv1-, cbv1+β3-, and cbv1+β4-mediated currents at low Ca2+i while inhibiting current at high Ca2+i, the potentiation–inhibition crossover occurring at 20 µM Ca2+i; (2) for cbv1+β1, cbv1+wt β2, and cbv1+β2-IR, this crossover was shifted to ∼3 µM Ca2+i. Second, applying Horrigan–Aldrich gating analysis on both phenotypes, we show that ethanol fails to modify intrinsic gating and the voltage-dependent parameters under examination. For cbv1, however, ethanol (a) drastically increases the channel’s apparent Ca2+ affinity (nine-times decrease in Kd) and (b) very mildly decreases allosteric coupling between Ca2+ binding and channel opening (C). The decreased Kd leads to increased channel activity. For cbv1+β1, ethanol (a) also decreases Kd

TRPV1 Channels Are Functionally Coupled with BK(mSlo1) Channels in Rat Dorsal Root Ganglion (DRG) Neurons

PubMed Central

Yan, Zonghe; Kong, Wenjuan; Liu, Beiying; Li, Xia; Yao, Jing; Zhang, Yuexuan; Qin, Feng; Ding, Jiuping

2013-01-01

The transient receptor potential vanilloid receptor 1 (TRPV1) channel is a nonselective cation channel activated by a variety of exogenous and endogenous physical and chemical stimuli, such as temperature (≥42 °C), capsaicin, a pungent compound in hot chili peppers, and allyl isothiocyanate. Large-conductance calcium- and voltage-activated potassium (BK) channels regulate the electric activities and neurotransmitter releases in excitable cells, responding to changes in membrane potentials and elevation of cytosolic calcium ions (Ca2+). However, it is unknown whether the TRPV1 channels are coupled with the BK channels. Using patch-clamp recording combined with an infrared laser device, we found that BK channels could be activated at 0 mV by a Ca2+ influx through TRPV1 channels not the intracellular calcium stores in submilliseconds. The local calcium concentration around BK is estimated over 10 μM. The crosstalk could be affected by 10 mM BAPTA, whereas 5 mM EGTA was ineffectual. Fluorescence and co-immunoprecipitation experiments also showed that BK and TRPV1 were able to form a TRPV1-BK complex. Furthermore, we demonstrated that the TRPV1-BK coupling also occurs in dosal root ganglion (DRG) cells, which plays a critical physiological role in regulating the “pain” signal transduction pathway in the peripheral nervous system. PMID:24147119

Co-infection with human polyomavirus BK enhances gene expression and replication of human adenovirus.

PubMed

Bil-Lula, Iwona; Woźniak, Mieczysław

2018-03-26

Immunocompromised patients are susceptible to multiple viral infections. Relevant interactions between co-infecting viruses might result from viral regulatory genes which trans-activate or repress the expression of host cell genes as well as the genes of any co-infecting virus. The aim of the current study was to show that the replication of human adenovirus 5 is enhanced by co-infection with BK polyomavirus and is associated with increased expression of proteins including early region 4 open reading frame 1 and both the large tumor antigen and small tumor antigen. Clinical samples of whole blood and urine from 156 hematopoietic stem cell transplant recipients were tested. We also inoculated adenocarcinomic human alveolar basal epithelial cells with both human adenovirus 5 and BK polyomavirus to evaluate if co-infection of viruses affected their replication. Data showed that adenovirus load was significantly higher in the plasma (mean 7.5 x 10 3  ± 8.5 x 10 2 copies/ml) and urine (mean 1.9 x 10 3  ± 8.0 x 10 2 copies/ml) of samples from patients with co-infections, in comparison to samples from patients with isolated adenovirus infection. In vitro co-infection led to an increased (8.6 times) expression of the adenovirus early region 4 open reading frame gene 48 hours post-inoculation. The expression of the early region 4 open reading frame gene positively correlated with the expression of BK polyomavirus large tumor antigen (r = 0.90, p < 0.0001) and small tumor antigen (r = 0.83, p < 0.001) genes. The enhanced expression of the early region 4 open reading frame gene due to co-infection with BK polyomavirus was associated with enhanced adenovirus, but not BK polyomavirus, replication. The current study provides evidence that co-infection of adenovirus and BK polyomavirus contributes to enhanced adenovirus replication. Data obtained from this study may have significant importance in the clinical setting.

Use of hybridot assay to screen for BK and JC polyomaviruses in non-immunosuppressed patients.

PubMed Central

Cobb, J J; Wickenden, C; Snell, M E; Hulme, B; Malcolm, A D; Coleman, D V

1987-01-01

Urine samples from 50 patients attending a genitourinary outpatient clinic and from 13 renal allograft recipients were investigated for evidence of infection with human BK and JC polyomaviruses using cytology and a new DNA hybridot assay. Forty four per cent of samples from the renal allograft recipients were positive by cytology and 75% by DNA hybridisation, indicating that hybridot assay is more sensitive than cytological screening. BK and JC viral DNA was found in 20% of the patients attending the genitourinary clinic, showing infection with BK virus and JC virus in a group of patients with clinical conditions not normally associated with immunological deficiency-a finding that has not been reported before. Images Figure PMID:3040812

Antecedent hydrogen sulfide elicits an anti-inflammatory phenotype in postischemic murine small intestine: role of BK channels

PubMed Central

Zuidema, Mozow Y.; Yang, Yan; Wang, Meifang; Kalogeris, Theodore; Liu, Yajun; Meininger, Cynthia J.; Hill, Michael A.; Davis, Michael J.

2010-01-01

The objectives of this study were to determine the role of calcium-activated, small (SK), intermediate (IK), and large (BK) conductance potassium channels in initiating the development of an anti-inflammatory phenotype elicited by preconditioning with an exogenous hydrogen sulfide (H2S) donor, sodium hydrosulfide (NaHS). Intravital microscopy was used to visualize rolling and firmly adherent leukocytes in vessels of the small intestine of mice preconditioned with NaHS (in the absence and presence of SK, IK, and BK channel inhibitors, apamin, TRAM-34, and paxilline, respectively) or SK/IK (NS-309) or BK channel activators (NS-1619) 24 h before ischemia-reperfusion (I/R). I/R induced marked increases in leukocyte rolling and adhesion, effects that were largely abolished by preconditioning with NaHS, NS-309, or NS-1619. The postischemic anti-inflammatory effects of NaHS-induced preconditioning were mitigated by BKB channel inhibitor treatment coincident with NaHS, but not by apamin or TRAM-34, 24 h before I/R. Confocal imaging and immunohistochemistry were used to demonstrate the presence of BKα subunit staining in both endothelial and vascular smooth muscle cells of isolated, pressurized mesenteric venules. Using patch-clamp techniques, we found that BK channels in cultured endothelial cells were activated after exposure to NaHS. Bath application of the same concentration of NaHS used in preconditioning protocols led to a rapid increase in a whole cell K+ current; specifically, the component of K+ current blocked by the selective BK channel antagonist iberiotoxin. The activation of BK current by NaHS could also be demonstrated in single channel recording mode where it was independent of a change in intracellular Ca+ concentration. Our data are consistent with the concept that H2S induces the development of an anti-adhesive state in I/R in part mediated by a BK channel-dependent mechanism. PMID:20833953

The BK(Ca) channels deficiency as a possible reason for radiation-induced vascular hypercontractility.

PubMed

Kyrychenko, Sergii; Tishkin, Sergey; Dosenko, Victor; Ivanova, Irina; Novokhatska, Tatiana; Soloviev, Anatoly

2012-01-01

It is likely that large-conductance Ca²⁺-activated K⁺ (BK(Ca)) channels channelopathy tightly involved in vascular malfunctions and arterial hypertension development. In the present study, we compared the results of siRNAs-induced α-BK(Ca) gene silencing and vascular abnormalities produced by whole-body ionized irradiation in rats. The experimental design comprised RT-PCR and patch clamp technique, thoracic aorta smooth muscle (SM) contractile recordings and arterial blood pressure (BP) measurements on the 30th day after whole body irradiation (6Gy) and following siRNAs KCNMA1 gene silencing in vivo. The expression profile of BK(Ca) mRNA transcripts in SM was significantly decreased in siRNAs-treated rats in a manner similar to irradiated SM. In contrast, the mRNA levels of K(v) and K(ATP) were significantly increased while L-type calcium channels mRNA transcripts demonstrated tendency to increment. The SMCs obtained from irradiated animals and after KCNMA1 gene silencing showed a significant decrease in total K⁺ current density amplitude. Paxilline (500 nM)-sensitive components of outward current were significantly decreased in both irradiated and gene silencing SMCs. KCNMA1 gene silencing increased SM sensitivity to norepinephrine while Ach-induced relaxation had decreased. The silencing of KCNMA1 had no significant effect on BP while radiation produced sustained arterial hypertension. Therefore, radiation alters the form and function of the BK(Ca) channel and this type of channelopathy may contribute to related vascular abnormalities. Nevertheless, it is unlikely that BK(Ca) can operate as a crucial factor for radiation-induced arterial hypertension. Copyright © 2012 Elsevier Inc. All rights reserved.

Ethanol-mediated relaxation of guinea pig urinary bladder smooth muscle: involvement of BK and L-type Ca2+ channels

PubMed Central

Malysz, John; Afeli, Serge A. Y.; Provence, Aaron

2013-01-01

Mechanisms underlying ethanol (EtOH)-induced detrusor smooth muscle (DSM) relaxation and increased urinary bladder capacity remain unknown. We investigated whether the large conductance Ca2+-activated K+ (BK) channels or L-type voltage-dependent Ca2+ channels (VDCCs), major regulators of DSM excitability and contractility, are targets for EtOH by patch-clamp electrophysiology (conventional and perforated whole cell and excised patch single channel) and isometric tension recordings using guinea pig DSM cells and isolated tissue strips, respectively. EtOH at 0.3% vol/vol (∼50 mM) enhanced whole cell BK currents at +30 mV and above, determined by the selective BK channel blocker paxilline. In excised patches recorded at +40 mV and ∼300 nM intracellular Ca2+ concentration ([Ca2+]), EtOH (0.1–0.3%) affected single BK channels (mean conductance ∼210 pS and blocked by paxilline) by increasing the open channel probability, number of open channel events, and open dwell-time constants. The amplitude of single BK channel currents and unitary conductance were not altered by EtOH. Conversely, at ∼10 μM but not ∼2 μM intracellular [Ca2+], EtOH (0.3%) decreased the single BK channel activity. EtOH (0.3%) affected transient BK currents (TBKCs) by either increasing frequency or decreasing amplitude, depending on the basal level of TBKC frequency. In isolated DSM strips, EtOH (0.1–1%) reduced the amplitude and muscle force of spontaneous phasic contractions. The EtOH-induced DSM relaxation, except at 1%, was attenuated by paxilline. EtOH (1%) inhibited L-type VDCC currents in DSM cells. In summary, we reveal the involvement of BK channels and L-type VDCCs in mediating EtOH-induced urinary bladder relaxation accommodating alcohol-induced diuresis. PMID:24153429

BK Channels Localize to the Paranodal Junction and Regulate Action Potentials in Myelinated Axons of Cerebellar Purkinje Cells.

PubMed

Hirono, Moritoshi; Ogawa, Yasuhiro; Misono, Kaori; Zollinger, Daniel R; Trimmer, James S; Rasband, Matthew N; Misonou, Hiroaki

2015-05-06

In myelinated axons, K(+) channels are clustered in distinct membrane domains to regulate action potentials (APs). At nodes of Ranvier, Kv7 channels are expressed with Na(+) channels, whereas Kv1 channels flank nodes at juxtaparanodes. Regulation of axonal APs by K(+) channels would be particularly important in fast-spiking projection neurons such as cerebellar Purkinje cells. Here, we show that BK/Slo1 channels are clustered at the paranodal junctions of myelinated Purkinje cell axons of rat and mouse. The paranodal junction is formed by a set of cell-adhesion molecules, including Caspr, between the node and juxtaparanodes in which it separates nodal from internodal membrane domains. Remarkably, only Purkinje cell axons have detectable paranodal BK channels, whose clustering requires the formation of the paranodal junction via Caspr. Thus, BK channels occupy this unique domain in Purkinje cell axons along with the other K(+) channel complexes at nodes and juxtaparanodes. To investigate the physiological role of novel paranodal BK channels, we examined the effect of BK channel blockers on antidromic AP conduction. We found that local application of blockers to the axon resulted in a significant increase in antidromic AP failure at frequencies above 100 Hz. We also found that Ni(2+) elicited a similar effect on APs, indicating the involvement of Ni(2+)-sensitive Ca(2+) channels. Furthermore, axonal application of BK channel blockers decreased the inhibitory synaptic response in the deep cerebellar nuclei. Thus, paranodal BK channels uniquely support high-fidelity firing of APs in myelinated Purkinje cell axons, thereby underpinning the output of the cerebellar cortex. Copyright © 2015 the authors 0270-6474/15/357082-13$15.00/0.

Intracellular segment between transmembrane helices S0 and S1 of BK channel α subunit contains two amphipathic helices connected by a flexible loop

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Pan; High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui, 230031; Li, Dong

2013-08-02

Highlights: •The loop between S0 and S1 of BK channel was overexpressed and purified in DPC. •NMR studies indicated BK-IS1 contained two helices connected by a flexible loop. •Mg{sup 2+} titration of BK-IS1 indicated two possible binding sites of divalent ions. -- Abstract: The BK channel, a tetrameric potassium channel with very high conductance, has a central role in numerous physiological functions. The BK channel can be activated by intracellular Ca{sup 2+} and Mg{sup 2+}, as well as by membrane depolarization. Unlike other tetrameric potassium channels, the BK channel has seven transmembrane helices (S0–S6) including an extra helix S0. Themore » intracellular segment between S0 and S1 (BK-IS1) is essential to BK channel functions and Asp99 in BK-IS1 is reported to be responsible for Mg{sup 2+} coordination. In this study, BK-IS1 (44–113) was over-expressed using a bacterial system and purified in the presence of detergent micelles for multidimensional heteronuclear nuclear magnetic resonance (NMR) structural studies. Backbone resonance assignment and secondary structure analysis showed that BK-IS1 contains two amphipathic helices connected by a 36-residue loop. Amide {sup 1}H–{sup 15}N heteronuclear NOE analysis indicated that the loop is very flexible, while the two amphipathic helices are possibly stabilized through interaction with the membrane. A solution NMR-based titration assay of BK-IS1 was performed with various concentrations of Mg{sup 2+}. Two residues (Thr45 and Leu46) with chemical shift changes were observed but no, or very minor, chemical shift difference was observed for Asp99, indicating a possible site for binding divalent ions or other modulation partners.« less

BK polyomavirus-associated hemorrhagic cystitis among pediatric allogeneic bone marrow transplant recipients: treatment response and evidence for nosocomial transmission.

PubMed

Koskenvuo, Minna; Dumoulin, Alexis; Lautenschlager, Irmeli; Auvinen, Eeva; Mannonen, Laura; Anttila, Veli-Jukka; Jahnukainen, Kirsi; Saarinen-Pihkala, Ulla M; Hirsch, Hans H

2013-01-01

BK polyomavirus-associated hemorrhagic cystitis (BK-PyVHC) is a significant complication of allogenic hematopoietic stem cell transplantation (HSCT), but risk factors and treatment are currently unresolved. BK-PyVHC typically presents with clinical cystitis, macrohematuria, and increasing urine and blood BKV loads. Characterization of children undergoing allogeneic HSCT with BK-PyVHC and their clinical and antibody response to cidofovir treatment. By prospective screening of urine and plasma in 50 pediatric allogenic HSCT performed between 2008 and 2010, we identified 6 (12%) children with BK-PyVHC. Cidofovir was administered intravenously to 5 patients and intravesically to 4 patients (3 double treatments). Decreasing BKV viremia of>2log(10)copies/mL and clinical resolution was seen in 4 patients over 5-12 weeks. Responses occurred only in patients mounting BKV-specific IgM and IgG responses. Epidemic curve plots, BKV genotyping and contact tracing provided evidence of transmission between 2 BKV-seronegative patients, but ruled out transmission among the remaining four patients The data suggest that BK-PyVHC may be the result of nosocomial transmission in children with low/undetectable BKV antibodies and raises urgent questions about appropriate infection control measures and the role of cidofovir. Copyright © 2012 Elsevier B.V. All rights reserved.

BK/TD models for analyzing in vitro impedance data on cytotoxicity.

PubMed

Teng, S; Barcellini-Couget, S; Beaudouin, R; Brochot, C; Desousa, G; Rahmani, R; Pery, A R R

2015-06-01

The ban of animal testing has enhanced the development of new in vitro technologies for cosmetics safety assessment. Impedance metrics is one such technology which enables monitoring of cell viability in real time. However, analyzing real time data requires moving from static to dynamic toxicity assessment. In the present study, we built mechanistic biokinetic/toxicodynamic (BK/TD) models to analyze the time course of cell viability in cytotoxicity assay using impedance. These models account for the fate of the tested compounds during the assay. BK/TD models were applied to analyze HepaRG cell viability, after single (48 h) and repeated (4 weeks) exposures to three hepatotoxic compounds (coumarin, isoeugenol and benzophenone-2). The BK/TD models properly fit the data used for their calibration that was obtained for single or repeated exposure. Only for one out of the three compounds, the models calibrated with a single exposure were able to predict repeated exposure data. We therefore recommend the use of long-term exposure in vitro data in order to adequately account for chronic hepatotoxic effects. The models we propose here are capable of being coupled with human biokinetic models in order to relate dose exposure and human hepatotoxicity. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

The oncogenic potential of BK-polyomavirus is linked to viral integration into the human genome.

PubMed

Kenan, Daniel J; Mieczkowski, Piotr A; Burger-Calderon, Raquel; Singh, Harsharan K; Nickeleit, Volker

2015-11-01

It has been suggested that BK-polyomavirus is linked to oncogenesis via high expression levels of large T-antigen in some urothelial neoplasms arising following kidney transplantation. However, a causal association between BK-polyomavirus, large T-antigen expression and oncogenesis has never been demonstrated in humans. Here we describe an investigation using high-throughput sequencing of tumour DNA obtained from an urothelial carcinoma arising in a renal allograft. We show that a novel BK-polyomavirus strain, named CH-1, is integrated into exon 26 of the myosin-binding protein C1 gene (MYBPC1) on chromosome 12 in tumour cells but not in normal renal cells. Integration of the BK-polyomavirus results in a number of discrete alterations in viral gene expression, including: (a) disruption of VP1 protein expression and robust expression of large T-antigen; (b) preclusion of viral replication; and (c) deletions in the non-coding control region (NCCR), with presumed alterations in promoter feedback loops. Viral integration disrupts one MYBPC1 gene copy and likely alters its expression. Circular episomal BK-polyomavirus gene sequences are not found, and the renal allograft shows no productive polyomavirus infection or polyomavirus nephropathy. These findings support the hypothesis that integration of polyomaviruses is essential to tumourigenesis. It is likely that dysregulation of large T-antigen, with persistent over-expression in non-lytic cells, promotes cell growth, genetic instability and neoplastic transformation. © 2015 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Prediction of Early BK Virus Infection in Kidney Transplant Recipients by the Number of Cells With Intranuclear Inclusion Bodies (Decoy Cells)

PubMed Central

Yamada, Yoshiteru; Tsuchiya, Tomohiro; Inagaki, Isao; Seishima, Mitsuru; Deguchi, Takashi

2018-01-01

Background BK virus (BKV) is the cause of nephropathy. Because BKV nephropathy can progress to graft loss, early diagnosis of BKV infection is very important. In this study, we aimed to investigate the utility of quantifying cells with intranuclear inclusion bodies (decoy cells) in urinary sediment for the screening and monitoring of BKV infection in renal transplant recipients at our hospital. Methods This was a retrospective single-center study. Urine sediment examination was performed at each outpatient visit, and the number of decoy cells was measured in the whole microscopic field. Patients (n = 41) were divided into the BK viremia group (blood positive for BKV DNA by polymerase chain reaction [PCR]) and non-BK viremia group (blood negative for BKV DNA by PCR), and the decoy cell count in urinary sediments was examined. Results The maximum decoy cell count was significantly higher (P = 0.04) in the BK viremia group than in the non-BK viremia group. In the receiver operating characteristic curve for the maximum decoy cells, the cutoff value was 507 cells. The area under the receiver operating characteristic curve was 0.8774 (95% confidence interval, 0.7739-0.9810). The number of decoy cells at the time of appearance in the BK viremia group was not significantly different from that in the non-BK viremia group. However, the BK viremia group showed an increasing trend, whereas the non-BK viremia group showed a decreasing trend, in the number of decoy cells. There was a positive correlation between the number of decoy cells and the data from the urine BKV-DNA PCR quantification (correlation coefficient [r] = 0.74). Conclusions Measurement of decoy cells in urinary sediments may predict early BKV infection, and if performed quickly, it may be useful for screening and continuous monitoring of BKV infection in renal transplant recipients. PMID:29464201

Hydronephrosis Resulting from Bilateral Ureteral Stenosis: A Late Complication of Polyoma BK Virus Cystitis?

PubMed

Basara, N; Rasche, F-M; Schwalenberg, T; Wickenhauser, C; Maier, M; Ivovic, J; Niederwieser, D; Lindner, T H

2010-01-01

We report here a case of acute lymphoblastic leukemia in remission presenting a late-onset bilateral hydronephrosis probably due to polyoma BK virus-induced proliferation of bladder endothelium on both ostii. The diagnosis was made virologically by BK virus Polymerase Chain Reaction (PCR) detection in the absence of any other bladder disease. Awareness of this late complication is necessary not only in patients after renal transplantation but also in patients after hematopoietic stem cell transplantation from matched unrelated donor.

The role of BK-type Ca2+-dependent K+ channels in spike broadening during repetitive firing in rat hippocampal pyramidal cells

PubMed Central

Shao, Li-Rong; Halvorsrud, Ragnhild; Borg-Graham, Lyle; Storm, Johan F

1999-01-01

The role of large-conductance Ca2+-dependent K+ channels (BK-channels; also known as maxi-K- or slo-channels) in spike broadening during repetitive firing was studied in CA1 pyramidal cells, using sharp electrode intracellular recordings in rat hippocampal slices, and computer modelling. Trains of action potentials elicited by depolarizing current pulses showed a progressive, frequency-dependent spike broadening, reflecting a reduced rate of repolarization. During a 50 ms long 5 spike train, the spike duration increased by 63·6 ± 3·4% from the 1st to the 3rd spike. The amplitude of the fast after-hyperpolarization (fAHP) also rapidly declined during each train. Suppression of BK-channel activity with (a) the selective BK-channel blocker iberiotoxin (IbTX, 60 nM), (b) the non-peptidergic BK-channel blocker paxilline (2–10 μM), or (c) calcium-free medium, broadened the 1st spike to a similar degree (≈60%). BK-channel suppression also caused a similar change in spike waveform as observed during repetitive firing, and eliminated (occluded) most of the spike broadening during repetitive firing. Computer simulations using a reduced compartmental model with transient BK-channel current and 10 other active ionic currents, produced an activity-dependent spike broadening that was strongly reduced when the BK-channel inactivation mechanism was removed. These results, which are supported by recent voltage-clamp data, strongly suggest that in CA1 pyramidal cells, fast inactivation of a transient BK-channel current (ICT), substantially contributes to frequency-dependent spike broadening during repetitive firing. PMID:10562340

Nanofinishing of BK7 glass using a magnetorheological solid rotating core tool.

PubMed

Kumar, Sumit; Singh, Anant Kumar

2018-02-01

Surface finishing is a promising method to improve the optical characteristics of crown glass. BK7 finds its applications in transmissive optics, i.e., lenses of binoculars, lenses of microscopes, lenses of telescopes, and light-emitting diodes. The magnetorheological (MR) nanofinishing of optical glasses using a solid rotating core tool is found more advantageous than the other advanced finishing processes in aspects such as precision and accuracy. In the present research, the MR nanofinishing with a solid rotating core tool is carried out on the BK7 glass of size 10×10×3  mm. Response surface methodology is conducted in order to find the optimum process parameters. The effects of process parameters on the percentage change in surface roughness are analyzed. The best surface roughness R a and R q values are achieved at 22 nm and 32 nm from the initial of 41 nm and 57 nm in 30 min of the finishing time cycle. To study the surface morphology of nanofinished BK7 glass, scanning electron microscopy is performed with sputter coating of gold on a glass specimen.

Differential Regulation of Action Potential Shape and Burst-Frequency Firing by BK and Kv2 Channels in Substantia Nigra Dopaminergic Neurons

PubMed Central

Kimm, Tilia; Khaliq, Zayd M.

2015-01-01

Little is known about the voltage-dependent potassium currents underlying spike repolarization in midbrain dopaminergic neurons. Studying mouse substantia nigra pars compacta dopaminergic neurons both in brain slice and after acute dissociation, we found that BK calcium-activated potassium channels and Kv2 channels both make major contributions to the depolarization-activated potassium current. Inhibiting Kv2 or BK channels had very different effects on spike shape and evoked firing. Inhibiting Kv2 channels increased spike width and decreased the afterhyperpolarization, as expected for loss of an action potential-activated potassium conductance. BK inhibition also increased spike width but paradoxically increased the afterhyperpolarization. Kv2 channel inhibition steeply increased the slope of the frequency–current (f–I) relationship, whereas BK channel inhibition had little effect on the f–I slope or decreased it, sometimes resulting in slowed firing. Action potential clamp experiments showed that both BK and Kv2 current flow during spike repolarization but with very different kinetics, with Kv2 current activating later and deactivating more slowly. Further experiments revealed that inhibiting either BK or Kv2 alone leads to recruitment of additional current through the other channel type during the action potential as a consequence of changes in spike shape. Enhancement of slowly deactivating Kv2 current can account for the increased afterhyperpolarization produced by BK inhibition and likely underlies the very different effects on the f–I relationship. The cross-regulation of BK and Kv2 activation illustrates that the functional role of a channel cannot be defined in isolation but depends critically on the context of the other conductances in the cell. SIGNIFICANCE STATEMENT This work shows that BK calcium-activated potassium channels and Kv2 voltage-activated potassium channels both regulate action potentials in dopamine neurons of the substantia nigra

Differential Regulation of Action Potential Shape and Burst-Frequency Firing by BK and Kv2 Channels in Substantia Nigra Dopaminergic Neurons.

PubMed

Kimm, Tilia; Khaliq, Zayd M; Bean, Bruce P

2015-12-16

Little is known about the voltage-dependent potassium currents underlying spike repolarization in midbrain dopaminergic neurons. Studying mouse substantia nigra pars compacta dopaminergic neurons both in brain slice and after acute dissociation, we found that BK calcium-activated potassium channels and Kv2 channels both make major contributions to the depolarization-activated potassium current. Inhibiting Kv2 or BK channels had very different effects on spike shape and evoked firing. Inhibiting Kv2 channels increased spike width and decreased the afterhyperpolarization, as expected for loss of an action potential-activated potassium conductance. BK inhibition also increased spike width but paradoxically increased the afterhyperpolarization. Kv2 channel inhibition steeply increased the slope of the frequency-current (f-I) relationship, whereas BK channel inhibition had little effect on the f-I slope or decreased it, sometimes resulting in slowed firing. Action potential clamp experiments showed that both BK and Kv2 current flow during spike repolarization but with very different kinetics, with Kv2 current activating later and deactivating more slowly. Further experiments revealed that inhibiting either BK or Kv2 alone leads to recruitment of additional current through the other channel type during the action potential as a consequence of changes in spike shape. Enhancement of slowly deactivating Kv2 current can account for the increased afterhyperpolarization produced by BK inhibition and likely underlies the very different effects on the f-I relationship. The cross-regulation of BK and Kv2 activation illustrates that the functional role of a channel cannot be defined in isolation but depends critically on the context of the other conductances in the cell. This work shows that BK calcium-activated potassium channels and Kv2 voltage-activated potassium channels both regulate action potentials in dopamine neurons of the substantia nigra pars compacta. Although both

Hydronephrosis Resulting from Bilateral Ureteral Stenosis: A Late Complication of Polyoma BK Virus Cystitis?

PubMed Central

Basara, N.; Rasche, F.-M.; Schwalenberg, T.; Wickenhauser, C.; Maier, M.; Ivovic, J.; Niederwieser, D.; Lindner, T. H.

2010-01-01

We report here a case of acute lymphoblastic leukemia in remission presenting a late-onset bilateral hydronephrosis probably due to polyoma BK virus-induced proliferation of bladder endothelium on both ostii. The diagnosis was made virologically by BK virus Polymerase Chain Reaction (PCR) detection in the absence of any other bladder disease. Awareness of this late complication is necessary not only in patients after renal transplantation but also in patients after hematopoietic stem cell transplantation from matched unrelated donor. PMID:20936157

Relative transmembrane segment rearrangements during BK channel activation resolved by structurally assigned fluorophore–quencher pairing

PubMed Central

Pantazis, Antonios

2012-01-01

Voltage-activated proteins can sense, and respond to, changes in the electric field pervading the cell membrane by virtue of a transmembrane helix bundle, the voltage-sensing domain (VSD). Canonical VSDs consist of four transmembrane helices (S1–S4) of which S4 is considered a principal component because it possesses charged residues immersed in the electric field. Membrane depolarization compels the charges, and by extension S4, to rearrange with respect to the field. The VSD of large-conductance voltage- and Ca-activated K+ (BK) channels exhibits two salient inconsistencies from the canonical VSD model: (1) the BK channel VSD possesses an additional nonconserved transmembrane helix (S0); and (2) it exhibits a “decentralized” distribution of voltage-sensing charges, in helices S2 and S3, in addition to S4. Considering these unique features, the voltage-dependent rearrangements of the BK VSD could differ significantly from the standard model of VSD operation. To understand the mode of operation of this unique VSD, we have optically tracked the relative motions of the BK VSD transmembrane helices during activation, by manipulating the quenching environment of site-directed fluorescent labels with native and introduced Trp residues. Having previously reported that S0 and S4 diverge during activation, in this work we demonstrate that S4 also diverges from S1 and S2, whereas S2, compelled by its voltage-sensing charged residues, moves closer to S1. This information contributes spatial constraints for understanding the BK channel voltage-sensing process, revealing the structural rearrangements in a non-canonical VSD. PMID:22802360

BK Virus-Associated Nephropathy: Current Situation in a Resource-Limited Country.

PubMed

Yooprasert, P; Rotjanapan, P

Data on BK virus-associated nephropathy (BKVAN) and treatment strategy in a resource-limited country are scarce. This study aimed to evaluate epidemiology of BKVAN and its situation in Thailand. A retrospective analysis was conducted among adult kidney transplant recipients at Ramathibodi Hospital from October 2011 to September 2016. Patients' demographic data, information on kidney transplantation, immunosuppressive therapy, cytomegalovirus and BK virus infections, and allograft outcomes were retrieved and analyzed. This study included 623 kidney transplant recipients. Only 327 patients (52.49%) received BK virus infection screening, and 176 of 327 patients had allograft dysfunction as a trigger for screening. BKVAN was identified in 39 of 327 patients (11.93%). Deceased donor transplantation and cytomegalovirus infection were associated with a higher risk of BKVAN (odds ratio = 2.2, P = .024, 95% confidence intervals [1.1, 4.43], and odds ratio = 2.6, P = .006, 95% confidence intervals [1.29, 5.26], respectively). BKVAN patients were at significantly higher risk for allograft rejection (P < .001) and allograft failure (P = .036). At the end of the study, 4 graft losses were documented (12.12%). BKVAN was associated with high rate of allograft rejection and failure. However, surveillance of its complications has been underperformed at our facility. Implementing a formal practice guideline may improve allograft outcome in resource-limited countries. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Single-channel kinetics of BK (Slo1) channels

PubMed Central

Geng, Yanyan; Magleby, Karl L.

2014-01-01

Single-channel kinetics has proven a powerful tool to reveal information about the gating mechanisms that control the opening and closing of ion channels. This introductory review focuses on the gating of large conductance Ca2+- and voltage-activated K+ (BK or Slo1) channels at the single-channel level. It starts with single-channel current records and progresses to presentation and analysis of single-channel data and the development of gating mechanisms in terms of discrete state Markov (DSM) models. The DSM models are formulated in terms of the tetrameric modular structure of BK channels, consisting of a central transmembrane pore-gate domain (PGD) attached to four surrounding transmembrane voltage sensing domains (VSD) and a large intracellular cytosolic domain (CTD), also referred to as the gating ring. The modular structure and data analysis shows that the Ca2+ and voltage dependent gating considered separately can each be approximated by 10-state two-tiered models with five closed states on the upper tier and five open states on the lower tier. The modular structure and joint Ca2+ and voltage dependent gating are consistent with a 50 state two-tiered model with 25 closed states on the upper tier and 25 open states on the lower tier. Adding an additional tier of brief closed (flicker states) to the 10-state or 50-state models improved the description of the gating. For fixed experimental conditions a channel would gate in only a subset of the potential number of states. The detected number of states and the correlations between adjacent interval durations are consistent with the tiered models. The examined models can account for the single-channel kinetics and the bursting behavior of gating. Ca2+ and voltage activate BK channels by predominantly increasing the effective opening rate of the channel with a smaller decrease in the effective closing rate. Ca2+ and depolarization thus activate by mainly destabilizing the closed states. PMID:25653620

BK potassium channels facilitate high-frequency firing and cause early spike frequency adaptation in rat CA1 hippocampal pyramidal cells

PubMed Central

Gu, Ning; Vervaeke, Koen; Storm, Johan F

2007-01-01

Neuronal potassium (K+) channels are usually regarded as largely inhibitory, i.e. reducing excitability. Here we show that BK-type calcium-activated K+ channels enhance high-frequency firing and cause early spike frequency adaptation in neurons. By combining slice electrophysiology and computational modelling, we investigated functions of BK channels in regulation of high-frequency firing in rat CA1 pyramidal cells. Blockade of BK channels by iberiotoxin (IbTX) selectively reduced the initial discharge frequency in response to strong depolarizing current injections, thus reducing the early spike frequency adaptation. IbTX also blocked the fast afterhyperpolarization (fAHP), slowed spike rise and decay, and elevated the spike threshold. Simulations with a computational model of a CA1 pyramidal cell confirmed that the BK channel-mediated rapid spike repolarization and fAHP limits activation of slower K+ channels (in particular the delayed rectifier potassium current (IDR)) and Na+ channel inactivation, whereas M-, sAHP- or SK-channels seem not to be important for the early facilitating effect. Since the BK current rapidly inactivates, its facilitating effect diminishes during the initial discharge, thus producing early spike frequency adaptation by an unconventional mechanism. This mechanism is highly frequency dependent. Thus, IbTX had virtually no effect at spike frequencies < 40 Hz. Furthermore, extracellular field recordings demonstrated (and model simulations supported) that BK channels contribute importantly to high-frequency burst firing in response to excitatory synaptic input to distal dendrites. These results strongly support the idea that BK channels play an important role for early high-frequency, rapidly adapting firing in hippocampal pyramidal neurons, thus promoting the type of bursting that is characteristic of these cells in vivo, during behaviour. PMID:17303637

Tagging of Endogenous BK Channels with a Fluorogen-Activating Peptide Reveals β4-Mediated Control of Channel Clustering in Cerebellum

PubMed Central

Pratt, Christopher P.; Kuljis, Dika A.; Homanics, Gregg E.; He, Jianjun; Kolodieznyi, Dmytro; Dudem, Srikanth; Hollywood, Mark A.; Barth, Alison L.; Bruchez, Marcel P.

2017-01-01

BK channels are critical regulators of neuronal activity, controlling firing, neurotransmitter release, cerebellar function, and BK channel mutations have been linked to seizure disorders. Modulation of BK channel gating is well characterized, regulated by accessory subunit interactions, intracellular signaling pathways, and membrane potential. In contrast, the role of intracellular trafficking mechanisms in controlling BK channel function, especially in live cells, has been less studied. Fluorogen-activating peptides (FAPs) are well-suited for trafficking and physiological studies due to the binding of malachite green (MG)-based dyes with sub-nanomolar affinity to the FAP, resulting in bright, photostable, far-red fluorescence. Cell-excluded MG dyes enable the selective tagging of surface protein and tracking through endocytic pathways. We used CRISPR to insert the FAP at the extracellular N-terminus of BKα in the first exon of its native locus, enabling regulation by the native promoter elements and tag incorporation into multiple splice isoforms. Motor coordination was found to be normal; however, BK channel expression seems to be reduced in some locations. Alternate start site selection or post-translational proteolytic processing resulted in incomplete FAP tagging of the BKα proteins in brain tissues. In Purkinje cell somata, FAP revealed BK channel clustering previously only observed by electron microscopy. Measurement of these clusters in β4+/- and β4-/- mice showed that puncta number and cluster fluorescence intensity on the soma are reduced in β4-/- knockout animals. This novel mouse line provides a versatile fluorescent platform for studying endogenous BK channels in living and fixed tissues. Future studies could apply this line to ex vivo neuronal cultures to study live-cell channel trafficking. PMID:29163049

Testosterone decreases urinary bladder smooth muscle excitability via novel signaling mechanism involving direct activation of the BK channels

PubMed Central

Hristov, Kiril L.; Parajuli, Shankar P.; Provence, Aaron

2016-01-01

In addition to improving sexual function, testosterone has been reported to have beneficial effects in ameliorating lower urinary tract symptoms by increasing bladder capacity and compliance, while decreasing bladder pressure. However, the cellular mechanisms by which testosterone regulates detrusor smooth muscle (DSM) excitability have not been elucidated. Here, we used amphotericin-B perforated whole cell patch-clamp and single channel recordings on inside-out excised membrane patches to investigate the regulatory role of testosterone in guinea pig DSM excitability. Testosterone (100 nM) significantly increased the depolarization-induced whole cell outward currents in DSM cells. The selective pharmacological inhibition of the large-conductance voltage- and Ca2+-activated K+ (BK) channels with paxilline (1 μM) completely abolished this stimulatory effect of testosterone, suggesting a mechanism involving BK channels. At a holding potential of −20 mV, DSM cells exhibited transient BK currents (TBKCs). Testosterone (100 nM) significantly increased TBKC activity in DSM cells. In current-clamp mode, testosterone (100 nM) significantly hyperpolarized the DSM cell resting membrane potential and increased spontaneous transient hyperpolarizations. Testosterone (100 nM) rapidly increased the single BK channel open probability in inside-out excised membrane patches from DSM cells, clearly suggesting a direct BK channel activation via a nongenomic mechanism. Live-cell Ca2+ imaging showed that testosterone (100 nM) caused a decrease in global intracellular Ca2+ concentration, consistent with testosterone-induced membrane hyperpolarization. In conclusion, the data provide compelling mechanistic evidence that under physiological conditions, testosterone at nanomolar concentrations directly activates BK channels in DSM cells, independent from genomic testosterone receptors, and thus regulates DSM excitability. PMID:27605581

Polyomavirus-Specific Cellular Immunity: From BK-Virus-Specific Cellular Immunity to BK-Virus-Associated Nephropathy?

PubMed Central

Dekeyser, Manon; François, Hélène; Beaudreuil, Séverine; Durrbach, Antoine

2015-01-01

In renal transplantation, BK-virus (BKV)-associated nephropathy has emerged as a major complication, with a prevalence of 1–10% and graft loss in >50% of cases. BKV is a member of the polyomavirus family and rarely induces apparent clinical disease in the general population. However, replication of polyomaviruses, associated with significant organ disease, is observed in patients with acquired immunosuppression. Monitoring of specific immunity combined with viral load could be used to individually assess the risk of viral reactivation and virus control. We review the current knowledge on BKV-specific cellular immunity and, more specifically, in immunocompromised patients. In the future, immune-based therapies could allow us to treat and prevent BKV-associated nephropathy. PMID:26136745

Monitoring of polyomavirus BK viruria in bone marrow transplantation patients by DNA hybridization assay and by polymerase chain reaction: an approach to assess the relationship between BK viruria and hemorrhagic cystitis.

PubMed

Azzi, A; Fanci, R; Bosi, A; Ciappi, S; Zakrzewska, K; de Santis, R; Laszlo, D; Guidi, S; Saccardi, R; Vannucchi, A M

1994-08-01

An association between long-lasting hemorrhagic cystitis (HC) in bone marrow transplantation (BMT) patients and viral infections, mostly with reactivation of the human polyomavirus BK (BKV), is suggested by several previous reports. We have carried out a prospective study in 55 (30 allogeneic, 24 autologous, 1 syngeneic) BMT recipients with the aim of evaluating the role of BKV in this frequent complication after BMT. To overcome the well known difficulties in BK virus isolation in cell cultures, a DNA hybridization assay and the polymerase chain reaction (PCR) were used for the detection and monitoring of viral urinary shedding, respectively. The presence of human polyomavirus JC and adenovirus DNA was also sought in urine specimens. BK viruria was demonstrated in 52.7% of patients (in 53.3% allogeneic and in 54.1% autologous BMT), whereas JCV and adenovirus were seldom present. Seven cases of HC (20% in allogeneic and 4% in autologous BMT) occurred and in all cases the clinical event was associated with BKV urinary shedding. This study suggests that BKV infection alone does not invariably lead to HC in BMT patients; for HC to occur the presence of other, at present unidentified, factors seems to be necessary.

Collinearly-improved BK evolution meets the HERA data

DOE PAGES

Iancu, E.; Madrigal, J. D.; Mueller, A. H.; ...

2015-10-03

In a previous publication, we have established a collinearly-improved version of the Balitsky–Kovchegov (BK) equation, which resums to all orders the radiative corrections enhanced by large double transverse logarithms. Here, we study the relevance of this equation as a tool for phenomenology, by confronting it to the HERA data. To that aim, we first improve the perturbative accuracy of our resummation, by including two classes of single-logarithmic corrections: those generated by the first non-singular terms in the DGLAP splitting functions and those expressing the one-loop running of the QCD coupling. The equation thus obtained includes all the next-to-leading order correctionsmore » to the BK equation which are enhanced by (single or double) collinear logarithms. Furthermore, we then use numerical solutions to this equation to fit the HERA data for the electron–proton reduced cross-section at small Bjorken x. We obtain good quality fits for physically acceptable initial conditions. Our best fit, which shows a good stability up to virtualities as large as Q 2 = 400 GeV 2 for the exchanged photon, uses as an initial condition the running-coupling version of the McLerran–Venugopalan model, with the QCD coupling running according to the smallest dipole prescription.« less

Intermittent losartan administration triggers cardiac post-conditioning in isolated rat hearts: role of BK2 receptors.

PubMed

Sgarra, Luca; Leo, Valentina; Addabbo, Francesco; Iacobazzi, Dominga; Carratù, Maria Rosaria; Montagnani, Monica; Potenza, Maria Assunta

2014-01-01

The angiotensin (Ang) and bradykinin (BK) tissue-system plays a pivotal role in post-conditioning, but the efficacy of angiotensin type 1 receptor (AT1R) blockers (ARBs) in post-ischemic strategies is still under investigation. We evaluated functional and morphological outcomes, together with activation of cytosolic RISK pathway kinases, in rat hearts subjected to losartan (LOS) or irbesartan (IRB) post-ischemic administration. Isolated rat hearts underwent 30 min ischemia and 120 min reperfusion. Post-conditioning was obtained by intermittent (10 s/each) or continuous drug infusion during the first 3 min of reperfusion. Left ventricular end-diastolic pressure (LVEDP), left ventricular developed pressure (dLVP), coronary flow (CF), and left ventricular infarct mass (IM) were measured together with the activation status of RISK kinases Akt, p42/44 MAPK and GSK3β. When compared to hearts subjected to ischemia/reperfusion (iI/R) alone, continuous IRB or LOS administration did not significantly reduce total infarct mass (cIRB or cLOS vs. iI/R, p = 0.2). Similarly, intermittent IRB (iIRB) was not able to enhance cardioprotection. Conversely, intermittent LOS administration (iLOS) significantly ameliorated cardiac recovery (iLOS vs iI/R, p<0.01). Differences between iLOS and iIRB persisted under continuous blockade of AT2R (iLOS+cPD vs. iIRB+cPD, p<0.05). Interestingly, iLOS cardioprotection was lost when BK2R was simultaneously blocked (iLOS+cHOE vs. iI/R, p = 0.6), whereas concurrent administration of iBK and iIRB replicated iLOS effects (iIRB+iBK vs. iLOS, p = 0.7). At the molecular level, iIRB treatment did not significantly activate RISK kinases, whereas both iLOS and iBK treatments were associated with activation of the Akt/GSK3β branch of the RISK pathways (p<0.05 vs. iI/R, for both). Our results suggest that intermittent losartan is effective in mediating post-conditioning cardioprotection, whereas irbesartan is not. The infarct mass reduction by intermittent

Intermittent Losartan Administration Triggers Cardiac Post-Conditioning in Isolated Rat Hearts: Role of BK2 Receptors

PubMed Central

Sgarra, Luca; Leo, Valentina; Addabbo, Francesco; Iacobazzi, Dominga; Carratù, Maria Rosaria; Montagnani, Monica; Potenza, Maria Assunta

2014-01-01

Introduction The angiotensin (Ang) and bradykinin (BK) tissue-system plays a pivotal role in post-conditioning, but the efficacy of angiotensin type 1 receptor (AT1R) blockers (ARBs) in post-ischemic strategies is still under investigation. We evaluated functional and morphological outcomes, together with activation of cytosolic RISK pathway kinases, in rat hearts subjected to losartan (LOS) or irbesartan (IRB) post-ischemic administration. Methods Isolated rat hearts underwent 30 min ischemia and 120 min reperfusion. Post-conditioning was obtained by intermittent (10 s/each) or continuous drug infusion during the first 3 min of reperfusion. Left ventricular end-diastolic pressure (LVEDP), left ventricular developed pressure (dLVP), coronary flow (CF), and left ventricular infarct mass (IM) were measured together with the activation status of RISK kinases Akt, p42/44 MAPK and GSK3β. Results When compared to hearts subjected to ischemia/reperfusion (iI/R) alone, continuous IRB or LOS administration did not significantly reduce total infarct mass (cIRB or cLOS vs. iI/R, p = 0.2). Similarly, intermittent IRB (iIRB) was not able to enhance cardioprotection. Conversely, intermittent LOS administration (iLOS) significantly ameliorated cardiac recovery (iLOS vs iI/R, p<0.01). Differences between iLOS and iIRB persisted under continuous blockade of AT2R (iLOS+cPD vs. iIRB+cPD, p<0.05). Interestingly, iLOS cardioprotection was lost when BK2R was simultaneously blocked (iLOS+cHOE vs. iI/R, p = 0.6), whereas concurrent administration of iBK and iIRB replicated iLOS effects (iIRB+iBK vs. iLOS, p = 0.7). At the molecular level, iIRB treatment did not significantly activate RISK kinases, whereas both iLOS and iBK treatments were associated with activation of the Akt/GSK3β branch of the RISK pathways (p<0.05 vs. iI/R, for both). Conclusions Our results suggest that intermittent losartan is effective in mediating post-conditioning cardioprotection, whereas irbesartan

Towards saturation of the electron-capture delayed fission probability: The new isotopes 240Es and 236Bk

NASA Astrophysics Data System (ADS)

Konki, J.; Khuyagbaatar, J.; Uusitalo, J.; Greenlees, P. T.; Auranen, K.; Badran, H.; Block, M.; Briselet, R.; Cox, D. M.; Dasgupta, M.; Di Nitto, A.; Düllmann, Ch. E.; Grahn, T.; Hauschild, K.; Herzán, A.; Herzberg, R.-D.; Heßberger, F. P.; Hinde, D. J.; Julin, R.; Juutinen, S.; Jäger, E.; Kindler, B.; Krier, J.; Leino, M.; Lommel, B.; Lopez-Martens, A.; Luong, D. H.; Mallaburn, M.; Nishio, K.; Pakarinen, J.; Papadakis, P.; Partanen, J.; Peura, P.; Rahkila, P.; Rezynkina, K.; Ruotsalainen, P.; Sandzelius, M.; Sarén, J.; Scholey, C.; Sorri, J.; Stolze, S.; Sulignano, B.; Theisen, Ch.; Ward, A.; Yakushev, A.; Yakusheva, V.

2017-01-01

The new neutron-deficient nuclei 240Es and 236Bk were synthesised at the gas-filled recoil separator RITU. They were identified by their radioactive decay chains starting from 240Es produced in the fusion-evaporation reaction 209Bi(34S,3n)240Es. Half-lives of 6 (2)s and 22-6+13s were obtained for 240Es and 236Bk, respectively. Two groups of α particles with energies Eα = 8.19 (3)MeV and 8.09 (3)MeV were unambiguously assigned to 240Es. Electron-capture delayed fission branches with probabilities of 0.16 (6) and 0.04 (2) were measured for 240Es and 236Bk, respectively. These new data show a continuation of the exponential increase of ECDF probabilities in more neutron-deficient isotopes.

Functional validation of Ca2+-binding residues from the crystal structure of the BK ion channel.

PubMed

Kshatri, Aravind S; Gonzalez-Hernandez, Alberto J; Giraldez, Teresa

2018-04-01

BK channels are dually regulated by voltage and Ca 2+ , providing a cellular mechanism to couple electrical and chemical signalling. Intracellular Ca 2+ concentration is sensed by a large cytoplasmic region in the channel known as "gating ring", which is formed by four tandems of regulator of conductance for K + (RCK1 and RCK2) domains. The recent crystal structure of the full-length BK channel from Aplysia californica has provided new information about the residues involved in Ca 2+ coordination at the high-affinity binding sites located in the RCK1 and RCK2 domains, as well as their cooperativity. Some of these residues have not been previously studied in the human BK channel. In this work we have investigated, through site directed mutagenesis and electrophysiology, the effects of these residues on channel activation by voltage and Ca 2+ . Our results demonstrate that the side chains of two non-conserved residues proposed to coordinate Ca 2+ in the A. californica structure (G523 and E591) have no apparent functional role in the human BK Ca 2+ sensing mechanism. Consistent with the crystal structure, our data indicate that in the human channel the conserved residue R514 participates in Ca 2+ coordination in the RCK1 binding site. Additionally, this study provides functional evidence indicating that R514 also interacts with residues E902 and Y904 connected to the Ca 2+ binding site in RCK2. Interestingly, it has been proposed that this interaction may constitute a structural correlate underlying the cooperative interactions between the two high-affinity Ca 2+ binding sites regulating the Ca 2+ dependent gating of the BK channel. This article is part of a Special Issue entitled: Beyond the Structure-Function Horizon of Membrane Proteins edited by Ute Hellmich, Rupak Doshi and Benjamin McIlwain. Copyright © 2017 Elsevier B.V. All rights reserved.

Calcium-activated potassium (BK) channels are encoded by duplicate slo1 genes in teleost fishes.

PubMed

Rohmann, Kevin N; Deitcher, David L; Bass, Andrew H

2009-07-01

Calcium-activated, large conductance potassium (BK) channels in tetrapods are encoded by a single slo1 gene, which undergoes extensive alternative splicing. Alternative splicing generates a high level of functional diversity in BK channels that contributes to the wide range of frequencies electrically tuned by the inner ear hair cells of many tetrapods. To date, the role of BK channels in hearing among teleost fishes has not been investigated at the molecular level, although teleosts account for approximately half of all extant vertebrate species. We identified slo1 genes in teleost and nonteleost fishes using polymerase chain reaction and genetic sequence databases. In contrast to tetrapods, all teleosts examined were found to express duplicate slo1 genes in the central nervous system, whereas nonteleosts that diverged prior to the teleost whole-genome duplication event express a single slo1 gene. Phylogenetic analyses further revealed that whereas other slo1 duplicates were the result of a single duplication event, an independent duplication occurred in a basal teleost (Anguilla rostrata) following the slo1 duplication in teleosts. A third, independent slo1 duplication (autotetraploidization) occurred in salmonids. Comparison of teleost slo1 genomic sequences to their tetrapod orthologue revealed a reduced number of alternative splice sites in both slo1 co-orthologues. For the teleost Porichthys notatus, a focal study species that vocalizes with maximal spectral energy in the range electrically tuned by BK channels in the inner ear, peripheral tissues show the expression of either one (e.g., vocal muscle) or both (e.g., inner ear) slo1 paralogues with important implications for both auditory and vocal physiology. Additional loss of expression of one slo1 paralogue in nonneural tissues in P. notatus suggests that slo1 duplicates were retained via subfunctionalization. Together, the results predict that teleost fish achieve a diversity of BK channel subfunction via

Calcium-Activated Potassium (BK) Channels Are Encoded by Duplicate slo1 Genes in Teleost Fishes

PubMed Central

Deitcher, David L.; Bass, Andrew H.

2009-01-01

Calcium-activated, large conductance potassium (BK) channels in tetrapods are encoded by a single slo1 gene, which undergoes extensive alternative splicing. Alternative splicing generates a high level of functional diversity in BK channels that contributes to the wide range of frequencies electrically tuned by the inner ear hair cells of many tetrapods. To date, the role of BK channels in hearing among teleost fishes has not been investigated at the molecular level, although teleosts account for approximately half of all extant vertebrate species. We identified slo1 genes in teleost and nonteleost fishes using polymerase chain reaction and genetic sequence databases. In contrast to tetrapods, all teleosts examined were found to express duplicate slo1 genes in the central nervous system, whereas nonteleosts that diverged prior to the teleost whole-genome duplication event express a single slo1 gene. Phylogenetic analyses further revealed that whereas other slo1 duplicates were the result of a single duplication event, an independent duplication occurred in a basal teleost (Anguilla rostrata) following the slo1 duplication in teleosts. A third, independent slo1 duplication (autotetraploidization) occurred in salmonids. Comparison of teleost slo1 genomic sequences to their tetrapod orthologue revealed a reduced number of alternative splice sites in both slo1 co-orthologues. For the teleost Porichthys notatus, a focal study species that vocalizes with maximal spectral energy in the range electrically tuned by BK channels in the inner ear, peripheral tissues show the expression of either one (e.g., vocal muscle) or both (e.g., inner ear) slo1 paralogues with important implications for both auditory and vocal physiology. Additional loss of expression of one slo1 paralogue in nonneural tissues in P. notatus suggests that slo1 duplicates were retained via subfunctionalization. Together, the results predict that teleost fish achieve a diversity of BK channel subfunction via

Iberiotoxin-sensitive and -insensitive BK currents in Purkinje neuron somata

PubMed Central

Benton, Mark D.; Lewis, Amanda H.; Bant, Jason S.

2013-01-01

Purkinje cells have specialized intrinsic ionic conductances that generate high-frequency action potentials. Disruptions of their Ca or Ca-activated K (KCa) currents correlate with altered firing patterns in vitro and impaired motor behavior in vivo. To examine the properties of somatic KCa currents, we recorded voltage-clamped KCa currents in Purkinje cell bodies isolated from postnatal day 17–21 mouse cerebellum. Currents were evoked by endogenous Ca influx with approximately physiological Ca buffering. Purkinje somata expressed voltage-activated, Cd-sensitive KCa currents with iberiotoxin (IBTX)-sensitive (>100 nS) and IBTX-insensitive (>75 nS) components. IBTX-sensitive currents activated and partially inactivated within milliseconds. Rapid, incomplete macroscopic inactivation was also evident during 50- or 100-Hz trains of 1-ms depolarizations. In contrast, IBTX-insensitive currents activated more slowly and did not inactivate. These currents were insensitive to the small- and intermediate-conductance KCa channel blockers apamin, scyllatoxin, UCL1684, bicuculline methiodide, and TRAM-34, but were largely blocked by 1 mM tetraethylammonium. The underlying channels had single-channel conductances of ∼150 pS, suggesting that the currents are carried by IBTX-resistant (β4-containing) large-conductance KCa (BK) channels. IBTX-insensitive currents were nevertheless increased by small-conductance KCa channel agonists EBIO, chlorzoxazone, and CyPPA. During trains of brief depolarizations, IBTX-insensitive currents flowed during interstep intervals, and the accumulation of interstep outward current was enhanced by EBIO. In current clamp, EBIO slowed spiking, especially during depolarizing current injections. The two components of BK current in Purkinje somata likely contribute differently to spike repolarization and firing rate. Moreover, augmentation of BK current may partially underlie the action of EBIO and chlorzoxazone to alleviate disrupted Purkinje cell

Clinical Utility of Urinary Cytology to Detect BK Viral Nephropathy.

PubMed

Nankivell, Brian J; Renthawa, Jasveen; Jeoffreys, Neisha; Kable, Kathy; O'Connell, Philip J; Chapman, Jeremy R; Wong, Germaine; Sharma, Raghwa N

2015-08-01

Reactivation of BK polyoma virus can result in destructive viral allograft nephropathy (BKVAN) with limited treatment options. Screening programs using surrogate markers of viral replication are important preventive strategies, guiding immunosuppression reduction. We prospectively evaluated the diagnostic test performance of urinary decoy cells and urinary SV40T immunochemistry of exfoliated cells, to screen for BKVAN, (defined by reference histology with SV40 immunohistochemistry, n = 704 samples), compared with quantitative viremia, from 211 kidney and 141 kidney-pancreas transplant recipients. The disease prevalence of BKVAN was 2.6%. Decoy cells occurred in 95 of 704 (13.5%) samples, with a sensitivity of 66.7%, specificity of 88.6%, positive predictive value (PPV) of 11.7%, and negative predictive value of 98.5% to predict histologically proven BKVAN. Quantification of decoy cells improved the PPV to 32.1% (10 ≥ cells threshold). Immunohistochemical staining of urinary exfoliated cells for SV40T improved sensitivity to 85.7%, detecting atypical or degenerate infected cells (specificity of 92.3% and PPV of 33.3%), but was hampered by technical failures. Viremia occurred in 90 of 704 (12.8%) with sensitivity of 96.3%, specificity of 90.3%, PPV of 31.5%, and negative predictive value of 99.8%. The receiver-operator curve performance of quantitative viremia surpassed decoy cells (area under the curve of 0.95 and 0.79, respectively, P = 0.0018 for differences). Combining decoy cell and BK viremia in a diagnostic matrix improved prediction of BKVAN and diagnostic risk stratification, especially for high-level positive results. Although quantified decoy cells are acceptable surrogate markers of BK viral replication with unexceptional test performances, quantitative viremia displayed superior test characteristics and is suggested as the screening test of choice.

BK Virus Load Associated with Serum Levels of sCD30 in Renal Transplant Recipients

PubMed Central

Malik, Salma N.; Al-Saffer, Jinan M.; Jawad, Rana S.

2016-01-01

Background. Rejection is the main drawback facing the renal transplant operations. Complicated and overlapping factors, mainly related to the immune system, are responsible for this rejection. Elevated serum levels of sCD30 were frequently recorded as an indicator for renal allograft rejection, while BV virus is considered as one of the most serious consequences for immunosuppressive treatment of renal transplant recipients (RTRs). Aims. This study aimed to determine the association of BK virus load with serum levels of sCD30 in RTRs suffering from nephropathy. Patients and Methods. A total of 50 RTRs with nephropathy and 30 age-matched apparently healthy individuals were recruited for this study. Serum samples were obtained from each participant. Real-time PCR was used to quantify BK virus load in RTRs serum, while ELISA technique was employed to estimate serum levels of sCD30. Results. Twenty-two percent of RTRs had detectable BKV with mean viral load of 1.094E + 06 ± 2.291E + 06. RTRs showed higher mean serum level of sCD30 (20.669 ± 18.713 U/mL) than that of controls (5.517 ± 5.304 U/mL) with significant difference. BK virus load had significant positive correlation with the serum levels of sCD30 in RTRs group. Conclusion. These results suggest that serum levels of sCD30 could be used as an indicator of BK viremia, and accordingly the immunosuppressive regime should be adjusted. PMID:27051424

BK Channels Are Required for Multisensory Plasticity in the Oculomotor System.

PubMed

Nelson, Alexandra B; Faulstich, Michael; Moghadam, Setareh; Onori, Kimberly; Meredith, Andrea; du Lac, Sascha

2017-01-04

Neural circuits are endowed with several forms of intrinsic and synaptic plasticity that could contribute to adaptive changes in behavior, but circuit complexities have hindered linking specific cellular mechanisms with their behavioral consequences. Eye movements generated by simple brainstem circuits provide a means for relating cellular plasticity to behavioral gain control. Here we show that firing rate potentiation, a form of intrinsic plasticity mediated by reductions in BK-type calcium-activated potassium currents in spontaneously firing neurons, is engaged during optokinetic reflex compensation for inner ear dysfunction. Vestibular loss triggers transient increases in postsynaptic excitability, occlusion of firing rate potentiation, and reductions in BK currents in vestibular nucleus neurons. Concurrently, adaptive increases in visually evoked eye movements rapidly restore oculomotor function in wild-type mice but are profoundly impaired in BK channel-null mice. Activity-dependent regulation of intrinsic excitability may be a general mechanism for adaptive control of behavioral output in multisensory circuits. Copyright © 2017 Elsevier Inc. All rights reserved.

Mechanisms underlying activation of transient BK current in rabbit urethral smooth muscle cells and its modulation by IP3-generating agonists

PubMed Central

Kyle, Barry D.; Bradley, Eamonn; Large, Roddy; Sergeant, Gerard P.; McHale, Noel G.; Thornbury, Keith D.

2013-01-01

We used the perforated patch-clamp technique at 37°C to investigate the mechanisms underlying the activation of a transient large-conductance K+ (tBK) current in rabbit urethral smooth muscle cells. The tBK current required an elevation of intracellular Ca2+, resulting from ryanodine receptor (RyR) activation via Ca2+-induced Ca2+ release, triggered by Ca2+ influx through L-type Ca2+ (CaV) channels. Carbachol inhibited tBK current by reducing Ca2+ influx and Ca2+ release and altered the shape of spike complexes recorded under current-clamp conditions. The tBK currents were blocked by iberiotoxin and penitrem A (300 and 100 nM, respectively) and were also inhibited when external Ca2+ was removed or the CaV channel inhibitors nifedipine (10 μM) and Cd2+ (100 μM) were applied. The tBK current was inhibited by caffeine (10 mM), ryanodine (30 μM), and tetracaine (100 μM), suggesting that RyR-mediated Ca2+ release contributed to the activation of the tBK current. When IP3 receptors (IP3Rs) were blocked with 2-aminoethoxydiphenyl borate (2-APB, 100 μM), the amplitude of the tBK current was not reduced. However, when Ca2+ release via IP3Rs was evoked with phenylephrine (1 μM) or carbachol (1 μM), the tBK current was inhibited. The effect of carbachol was abolished when IP3Rs were blocked with 2-APB or by inhibition of muscarinic receptors with the M3 receptor antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (1 μM). Under current-clamp conditions, bursts of action potentials could be evoked with depolarizing current injection. Carbachol reduced the number and amplitude of spikes in each burst, and these effects were reduced in the presence of 2-APB. In the presence of ryanodine, the number and amplitude of spikes were also reduced, and carbachol was without further effect. These data suggest that IP3-generating agonists can modulate the electrical activity of rabbit urethral smooth muscle cells and may contribute to the effects of neurotransmitters on

Comprehensive benchmarking reveals H2BK20 acetylation as a distinctive signature of cell-state-specific enhancers and promoters.

PubMed

Kumar, Vibhor; Rayan, Nirmala Arul; Muratani, Masafumi; Lim, Stefan; Elanggovan, Bavani; Xin, Lixia; Lu, Tess; Makhija, Harshyaa; Poschmann, Jeremie; Lufkin, Thomas; Ng, Huck Hui; Prabhakar, Shyam

2016-05-01

Although over 35 different histone acetylation marks have been described, the overwhelming majority of regulatory genomics studies focus exclusively on H3K27ac and H3K9ac. In order to identify novel epigenomic traits of regulatory elements, we constructed a benchmark set of validated enhancers by performing 140 enhancer assays in human T cells. We tested 40 chromatin signatures on this unbiased enhancer set and identified H2BK20ac, a little-studied histone modification, as the most predictive mark of active enhancers. Notably, we detected a novel class of functionally distinct enhancers enriched in H2BK20ac but lacking H3K27ac, which was present in all examined cell lines and also in embryonic forebrain tissue. H2BK20ac was also unique in highlighting cell-type-specific promoters. In contrast, other acetylation marks were present in all active promoters, regardless of cell-type specificity. In stimulated microglial cells, H2BK20ac was more correlated with cell-state-specific expression changes than H3K27ac, with TGF-beta signaling decoupling the two acetylation marks at a subset of regulatory elements. In summary, our study reveals a previously unknown connection between histone acetylation and cell-type-specific gene regulation and indicates that H2BK20ac profiling can be used to uncover new dimensions of gene regulation. © 2016 Kumar et al.; Published by Cold Spring Harbor Laboratory Press.

Comprehensive benchmarking reveals H2BK20 acetylation as a distinctive signature of cell-state-specific enhancers and promoters

PubMed Central

Kumar, Vibhor; Rayan, Nirmala Arul; Muratani, Masafumi; Lim, Stefan; Elanggovan, Bavani; Xin, Lixia; Lu, Tess; Makhija, Harshyaa; Poschmann, Jeremie; Lufkin, Thomas; Ng, Huck Hui; Prabhakar, Shyam

2016-01-01

Although over 35 different histone acetylation marks have been described, the overwhelming majority of regulatory genomics studies focus exclusively on H3K27ac and H3K9ac. In order to identify novel epigenomic traits of regulatory elements, we constructed a benchmark set of validated enhancers by performing 140 enhancer assays in human T cells. We tested 40 chromatin signatures on this unbiased enhancer set and identified H2BK20ac, a little-studied histone modification, as the most predictive mark of active enhancers. Notably, we detected a novel class of functionally distinct enhancers enriched in H2BK20ac but lacking H3K27ac, which was present in all examined cell lines and also in embryonic forebrain tissue. H2BK20ac was also unique in highlighting cell-type-specific promoters. In contrast, other acetylation marks were present in all active promoters, regardless of cell-type specificity. In stimulated microglial cells, H2BK20ac was more correlated with cell-state-specific expression changes than H3K27ac, with TGF-beta signaling decoupling the two acetylation marks at a subset of regulatory elements. In summary, our study reveals a previously unknown connection between histone acetylation and cell-type-specific gene regulation and indicates that H2BK20ac profiling can be used to uncover new dimensions of gene regulation. PMID:26957309

Towards industrial ultrafast laser microwelding: SiO2 and BK7 to aluminum alloy.

PubMed

Carter, Richard M; Troughton, Michael; Chen, Jianyong; Elder, Ian; Thomson, Robert R; Daniel Esser, M J; Lamb, Robert A; Hand, Duncan P

2017-06-01

We report systematic analysis and comparison of ps-laser microwelding of industry relevant Al6082 parts to SiO 2 and BK7. Parameter mapping of pulse energy and focal depth on the weld strength is presented. The welding process was found to be strongly dependent on the focal plane but has a large tolerance to variation in pulse energy. Accelerated lifetime tests by thermal cycling from -50° to +90°C are presented. Welds in Al6082-BK7 parts survive over the full temperature range where the ratio of thermal expansion coefficients is 3.4:1. Welds in Al6082-SiO 2 parts (ratio 47.1:1) survive only a limited temperature range.

Nitric oxide decreases the excitability of interstitial cells of Cajal through activation of the BK channel

PubMed Central

Zhu, Yaohui; Huizinga, Jan D

2008-01-01

Abstract Nitrergic nerves are structurally and functionally associated with ICC. To further understand mechanisms of communication, the hypothesis was investigated that NO might affect large conductance K channels. To that end, we searched for IbTX-sensitive currents in ICC obtained through explant cultures from the mouse small intestine and studied effects of the NOS inhibitor omega N-nitro-L-arginine (LNNA) and the NO donor sodium nitroprusside (SNP). IbTX-sensitive currents acquired in the whole-cell configuration through nystatin perforated patches exhibited high noise levels but relatively low amplitude, whereas currents obtained in the conventional whole-cell configuration exhibited less noise and higher amplitudes; depolarization from −80 to + 40 mV evoked 357 ± 159 pA current in the nystatin perforated patch configuration and 1075 ± 597 pA using the conventional whole-cell configuration. Immunohistochemistry showed that ICC associated with ganglia and Auerbach's plexus nerve fibers were immunoreactive to BK antibodies. The IbTX-sensitive currents were increased by SNP and inhibited by LNNA. BK blockers suppressed spontaneous transit outward currents in ICC. After block of BK currents, or before these currents became prominent, calcium currents were activated by depolarization in the same cells. Their peak amplitude occurred at −25 mV and the currents were increased with increasing extracellular calcium and inhibited by cobalt. The hypothesis is warranted that nitrergic innervation inhibits ICC excitability in part through activation of BK channels. In addition, NO is an intracellular regulator of ICC excitability. PMID:18194464

Recombined sequences between the non-coding control regions of JC and BK viruses found in the urine of a renal transplantation patient.

PubMed

Liaw, Yu-Ching; Chen, Cheng-Hsu; Shu, Kuo-Hsiung; Fang, Chiung-Yao; Ou, Wei-Chih; Chen, Pei-Lain; Shen, Cheng-Huang; Lin, Mien-Chun; Chang, Deching; Wang, Meilin

2012-12-01

Kidney cells are the common host for JC virus (JCV) and BK virus (BKV). Reactivation of JCV and/or BKV in patients after organ transplantation, such as renal transplantation, may cause hemorrhagic cystitis and polyomavirus-associated nephropathy. Furthermore, JCV and BKV may be shed in the urine after reactivation in the kidney. Rearranged as well as archetypal non-coding control regions (NCCRs) of JCV and BKV have been frequently identified in human samples. In this study, three JC/BK recombined NCCR sequences were identified in the urine of a patient who had undergone renal transplantation. They were designated as JC-BK hybrids 1, 2, and 3. The three JC/BK recombinant NCCRs contain up-stream JCV as well as down-stream BKV sequences. Deletions of both JCV and BKV sequences were found in these recombined NCCRs. Recombination of DNA sequences between JCV and BKV may occur during co-infection due to the relatively high homology of the two viral genomes.

Broadening roles for FMRP: big news for big potassium (BK) channels.

PubMed

Contractor, Anis

2013-02-20

FMRP is an RNA-binding protein that negatively regulates translation and which is lost in fragile X syndrome. In this issue of Neuron, Deng et al. (2013) demonstrate a novel translation-independent function for FMRP as a regulator of presynaptic BK channels that modulate the dynamics of neurotransmitter release. Copyright © 2013 Elsevier Inc. All rights reserved.

The temperature dependence of the BK channel activity - kinetics, thermodynamics, and long-range correlations.

PubMed

Wawrzkiewicz-Jałowiecka, Agata; Dworakowska, Beata; Grzywna, Zbigniew J

2017-10-01

Large-conductance, voltage dependent, Ca 2+ -activated potassium channels (BK) are transmembrane proteins that regulate many biological processes by controlling potassium flow across cell membranes. Here, we investigate to what extent temperature (in the range of 17-37°C with ΔT=5°C step) is a regulating parameter of kinetic properties of the channel gating and memory effect in the series of dwell-time series of subsequent channel's states, at membrane depolarization and hyperpolarization. The obtained results indicate that temperature affects strongly the BK channels' gating, but, counterintuitively, it exerts no effect on the long-range correlations, as measured by the Hurst coefficient. Quantitative differences between dependencies of appropriate channel's characteristics on temperature are evident for different regimes of voltage. Examining the characteristics of BK channel activity as a function of temperature allows to estimate the net activation energy (E act ) and changes of thermodynamic parameters (ΔH, ΔS, ΔG) by channel opening. Larger E act corresponds to the channel activity at membrane hyperpolarization. The analysis of entropy and enthalpy changes of closed to open channel's transition suggest the entropy-driven nature of the increase of open state probability during voltage activation and supports the hypothesis about the voltage-dependent geometry of the channel vestibule. Copyright © 2017 Elsevier B.V. All rights reserved.

Deletion of cytosolic gating ring decreases gate and voltage sensor coupling in BK channels.

PubMed

Zhang, Guohui; Geng, Yanyan; Jin, Yakang; Shi, Jingyi; McFarland, Kelli; Magleby, Karl L; Salkoff, Lawrence; Cui, Jianmin

2017-03-06

Large conductance Ca 2+ -activated K + channels (BK channels) gate open in response to both membrane voltage and intracellular Ca 2+ The channel is formed by a central pore-gate domain (PGD), which spans the membrane, plus transmembrane voltage sensors and a cytoplasmic gating ring that acts as a Ca 2+ sensor. How these voltage and Ca 2+ sensors influence the common activation gate, and interact with each other, is unclear. A previous study showed that a BK channel core lacking the entire cytoplasmic gating ring (Core-MT) was devoid of Ca 2+ activation but retained voltage sensitivity (Budelli et al. 2013. Proc. Natl. Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1313433110). In this study, we measure voltage sensor activation and pore opening in this Core-MT channel over a wide range of voltages. We record gating currents and find that voltage sensor activation in this truncated channel is similar to WT but that the coupling between voltage sensor activation and gating of the pore is reduced. These results suggest that the gating ring, in addition to being the Ca 2+ sensor, enhances the effective coupling between voltage sensors and the PGD. We also find that removal of the gating ring alters modulation of the channels by the BK channel's β1 and β2 subunits. © 2017 Zhang et al.

Deletion of cytosolic gating ring decreases gate and voltage sensor coupling in BK channels

PubMed Central

Zhang, Guohui; Shi, Jingyi; McFarland, Kelli; Magleby, Karl L.; Salkoff, Lawrence

2017-01-01

Large conductance Ca2+-activated K+ channels (BK channels) gate open in response to both membrane voltage and intracellular Ca2+. The channel is formed by a central pore-gate domain (PGD), which spans the membrane, plus transmembrane voltage sensors and a cytoplasmic gating ring that acts as a Ca2+ sensor. How these voltage and Ca2+ sensors influence the common activation gate, and interact with each other, is unclear. A previous study showed that a BK channel core lacking the entire cytoplasmic gating ring (Core-MT) was devoid of Ca2+ activation but retained voltage sensitivity (Budelli et al. 2013. Proc. Natl. Acad. Sci. USA. http://dx.doi.org/10.1073/pnas.1313433110). In this study, we measure voltage sensor activation and pore opening in this Core-MT channel over a wide range of voltages. We record gating currents and find that voltage sensor activation in this truncated channel is similar to WT but that the coupling between voltage sensor activation and gating of the pore is reduced. These results suggest that the gating ring, in addition to being the Ca2+ sensor, enhances the effective coupling between voltage sensors and the PGD. We also find that removal of the gating ring alters modulation of the channels by the BK channel’s β1 and β2 subunits. PMID:28196879

BK virus (BKV) plasma dynamics in patients with BKV-associated hemorrhagic cystitis following allogeneic stem cell transplantation.

PubMed

Drew, R J; Walsh, A; Ní Laoi, B; Conneally, E; Crowley, B

2013-06-01

The use of real-time polymerase chain reaction testing in the investigation of BK virus (BKV)-associated disease has been widely studied in renal transplant recipients; however, far less research has been done in this area with respect to the plasma BK viral load dynamics of BKV hemorrhagic cystitis (BKV-HC) in hematopoietic stem cell transplant recipients. The aim of this study was to examine the BK viral load dynamics in plasma samples collected from patients post transplant who had laboratory-confirmed BKV-HC. Patients who developed BK viremia were compared with patients who did not develop viremia, and a statistical comparison of risk factors for viremia was performed. Seventeen patients were included in this study. Urine samples from the day of BKV diagnosis were available in 13 of the 17 cases. In total, 154 archived plasma samples from around the time of the BKV-HC event were also included in the study from these 17 patients. The median time from transplantation to the onset of detectable viremia was 68 days. The median viral load in the 13 urine samples was 1.8 × 10(8) copies/mL, which was significantly higher than the median viral load in the 38 positive plasma samples of 6.6 × 10(2) copies/mL (Mann-Whitney test, U = 16, P < 0.001). The lymphocyte count on the day of the positive BKV test was significantly lower in patients with BKV viremia than in patients with no viremia (P = 0.02) and also the white cell and platelet counts were lower on the day of the first positive BKV test. Although there is not inter-patient consistency as regards correlation between urinary BK viral loads and severity of clinical BKV-HC, in individual patients the decline in viral load in plasma did correlate with clinical recovery. © 2013 John Wiley & Sons A/S.

Cysteine residue 911 in C-terminal tail of human BK(Ca)α channel subunit is crucial for its activation by carbon monoxide.

PubMed

Telezhkin, Vsevolod; Brazier, Stephen P; Mears, Ruth; Müller, Carsten T; Riccardi, Daniela; Kemp, Paul J

2011-06-01

The large conductance, voltage- and calcium-activated potassium channel, BK(Ca), is a known target for the gasotransmitter, carbon monoxide (CO). Activation of BK(Ca) by CO modulates cellular excitability and contributes to the physiology of a diverse array of processes, including vascular tone and oxygen-sensing. Currently, there is no consensus regarding the molecular mechanisms underpinning reception of CO by the BK(Ca). Here, employing voltage-clamped, inside-out patches from HEK293 cells expressing single, double and triple cysteine mutations in the BK(Ca) α-subunit, we test the hypothesis that CO regulation is conferred upon the channel by interactions with cysteine residues within the RCK2 domain. In physiological [Ca(2+)](i), all mutants carrying a cysteine substitution at position 911 (C911G) demonstrated significantly reduced CO sensitivity; the C911G mutant did not express altered Ca(2+)-sensitivity. In contrast, histidine residues in RCK1 domain, previously shown to ablate CO activation in low [Ca(2+)](i), actually increased CO sensitivity when [Ca(2+)](i) was in the physiological range. Importantly, cyanide, employed here as a substituent for CO at potential metal centres, occluded activation by CO; this effect was freely reversible. Taken together, these data suggest that a specific cysteine residue in the C-terminal domain, which is close to the Ca(2+) bowl but which is not involved in Ca(2+) activation, confers significant CO sensitivity to BK(Ca) channels. The rapid reversibility of CO and cyanide binding, coupled to information garnered from other CO-binding proteins, suggests that C911 may be involved in formation of a transition metal cluster which can bind and, thereafter, activate BK(Ca).

Determination of the Stoichiometry between α- and γ1 Subunits of the BK Channel Using LRET.

PubMed

Carrasquel-Ursulaez, Willy; Alvarez, Osvaldo; Bezanilla, Francisco; Latorre, Ramon

2018-06-05

Two families of accessory proteins, β and γ, modulate BK channel gating and pharmacology. Notably, in the absence of internal Ca 2+ , the γ1 subunit promotes a large shift of the BK conductance-voltage curve to more negative potentials. However, very little is known about how α- and γ1 subunits interact. In particular, the association stoichiometry between both subunits is unknown. Here, we propose a method to answer this question using lanthanide resonance energy transfer. The method assumes that the kinetics of lanthanide resonance energy transfer-sensitized emission of the donor double-labeled α/γ1 complex is the linear combination of the kinetics of the sensitized emission in single-labeled complexes. We used a lanthanide binding tag engineered either into the α- or the γ1 subunits to bind Tb +3 as the donor. The acceptor (BODIPY) was attached to the BK pore-blocker iberiotoxin. We determined that γ1 associates with the α-subunit with a maximal 1:1 stoichiometry. This method could be applied to determine the stoichiometry of association between proteins within heteromultimeric complexes. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Phase 1b randomized trial and follow-up study in Uganda of the blood-stage malaria vaccine candidate BK-SE36.

PubMed

Palacpac, Nirianne Marie Q; Ntege, Edward; Yeka, Adoke; Balikagala, Betty; Suzuki, Nahoko; Shirai, Hiroki; Yagi, Masanori; Ito, Kazuya; Fukushima, Wakaba; Hirota, Yoshio; Nsereko, Christopher; Okada, Takuya; Kanoi, Bernard N; Tetsutani, Kohhei; Arisue, Nobuko; Itagaki, Sawako; Tougan, Takahiro; Ishii, Ken J; Ueda, Shigeharu; Egwang, Thomas G; Horii, Toshihiro

2013-01-01

Up to now a malaria vaccine remains elusive. The Plasmodium falciparum serine repeat antigen-5 formulated with aluminum hydroxyl gel (BK-SE36) is a blood-stage malaria vaccine candidate that has undergone phase 1a trial in malaria-naive Japanese adults. We have now assessed the safety and immunogenicity of BK-SE36 in a malaria endemic area in Northern Uganda. We performed a two-stage, randomized, single-blinded, placebo-controlled phase 1b trial (Current Controlled trials ISRCTN71619711). A computer-generated sequence randomized healthy subjects for 2 subcutaneous injections at 21-day intervals in Stage1 (21-40 year-olds) to 1-mL BK-SE36 (BKSE1.0) (n = 36) or saline (n = 20) and in Stage2 (6-20 year-olds) to BKSE1.0 (n = 33), 0.5-mL BK-SE36 (BKSE0.5) (n = 33), or saline (n = 18). Subjects and laboratory personnel were blinded. Safety and antibody responses 21-days post-second vaccination (Day42) were assessed. Post-trial, to compare the risk of malaria episodes 130-365 days post-second vaccination, Stage2 subjects were age-matched to 50 control individuals. Nearly all subjects who received BK-SE36 had induration (Stage1, n = 33, 92%; Stage2, n = 63, 96%) as a local adverse event. No serious adverse event related to BK-SE36 was reported. Pre-existing anti-SE36 antibody titers negatively correlated with vaccination-induced antibody response. At Day42, change in antibody titers was significant for seronegative adults (1.95-fold higher than baseline [95% CI, 1.56-2.43], p = 0.004) and 6-10 year-olds (5.71-fold [95% CI, 2.38-13.72], p = 0.002) vaccinated with BKSE1.0. Immunogenicity response to BKSE0.5 was low and not significant (1.55-fold [95% CI, 1.24-1.94], p = 0.75). In the ancillary analysis, cumulative incidence of first malaria episodes with ≥5000 parasites/µL was 7 cases/33 subjects in BKSE1.0 and 10 cases/33 subjects in BKSE0.5 vs. 29 cases/66 subjects in the control group. Risk ratio for BKSE1.0 was 0.48 (95% CI, 0

Relationship of BK polyoma virus (BKV) in the urine with hemorrhagic cystitis and renal function in recipients of T Cell-depleted peripheral blood and cord blood stem cell transplantations.

PubMed

Lee, Yeon Joo; Zheng, Junting; Kolitsopoulos, Yovanna; Chung, Dick; Amigues, Isabelle; Son, Tammy; Choo, Kathleen; Hester, Jeff; Giralt, Sergio A; Glezerman, Ilya G; Jakubowski, Ann A; Papanicolaou, Genovefa A

2014-08-01

Hematopoietic stem cell transplant (HSCT) recipients are at significant risk for BK virus (BKV) reactivation, hemorrhagic cystitis (HC), and renal dysfunction. We prospectively monitored 98 patients who had received HSCT by serial BKV PCR in the urine through day (D) +100 to analyze the relationship between BK viruria and HC, serum creatinine (Cr), and creatinine clearance (CrCl) through D +180 or death. Patients, median age 52 years (range, 20 to 73), received T cell-depleted (50%) or cord blood allografts (21%). Median pre-HSCT BKV IgG titers were 1:10,240. Incremental increase in BKV IgG titers correlated with developing BK viruria ≥ 10(7) copies/mL. By D +100, 53 (54%) patients had BK viruria. BKV load in the urine increased at engraftment and persisted throughout D +100. HC developed in 10 patients (10%); 7 of 10 with BK viruria. In competing risk analyses, BK viruria ≥ 10(7) copies/mL, older age, cytomegalovirus reactivation, and foscarnet use were risk factors for HC. Cr and CrCl at 2, 3, and 6 months after HSCT were similar between patients with and without BK viruria. Copyright © 2014 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

Polyomavirus BK non-coding control region rearrangements in health and disease.

PubMed

Sharma, Preety M; Gupta, Gaurav; Vats, Abhay; Shapiro, Ron; Randhawa, Parmjeet S

2007-08-01

BK virus is an increasingly recognized pathogen in transplanted patients. DNA sequencing of this virus shows considerable genomic variability. To understand the clinical significance of rearrangements in the non-coding control region (NCCR) of BK virus (BKV), we report a meta-analysis of 507 sequences, including 40 sequences generated in our own laboratory, for associations between rearrangements and disease, tissue tropism, geographic origin, and viral genotype. NCCR rearrangements were less frequent in (a) asymptomatic BKV viruria compared to patients viral nephropathy (1.7% vs. 22.5%), and (b) viral genotype 1 compared to other genotypes (2.4% vs. 11.2%). Rearrangements were commoner in malignancy (78.6%), and Norwegians (45.7%), and less common in East Indians (0%), and Japanese (4.3%). A surprising number of rearranged sequences were reported from mononuclear cells of healthy subjects, whereas most plasma sequences were archetypal. This difference could not be related to potential recombinase activity in lymphocytes, as consensus recombination signal sequences could not be found in the NCCR region. NCCR rearrangements are neither required nor a sufficient condition to produce clinical disease. BKV nephropathy and hemorrhagic cystitis are not associated with any unique NCCR configuration or nucleotide sequence.

Type 2 diabetes elicits lower nitric oxide, bradykinin concentration and kallikrein activity together with higher DesArg(9)-BK and reduced post-exercise hypotension compared to non-diabetic condition.

PubMed

Simões, Herbert Gustavo; Asano, Ricardo Yukio; Sales, Marcelo Magalhães; Browne, Rodrigo Alberto Vieira; Arsa, Gisela; Motta-Santos, Daisy; Puga, Guilherme Morais; Lima, Laila Cândida de Jesus; Campbell, Carmen Sílvia Grubert; Franco, Octavio Luiz

2013-01-01

This study compared the plasma kallikrein activity (PKA), bradykinin concentration (BK), DesArg(9)-BK production, nitric oxide release (NO) and blood pressure (BP) response after moderate-intensity aerobic exercise performed by individuals with and without type 2 diabetes. Ten subjects with type 2 diabetes (T2D) and 10 without type 2 diabetes (ND) underwent three sessions: 1) maximal incremental test on cycle ergometer to determine lactate threshold (LT); 2) 20-min of constant-load exercise on cycle ergometer, at 90% LT and; 3) control session. BP and oxygen uptake were measured at rest and at 15, 30 and 45 min post-exercise. Venous blood samples were collected at 15 and 45 minutes of the recovery period for further analysis of PKA, BK and DesArg(9)-BK. Nitrite plus nitrate (NOx) was analyzed at 15 minutes post exercise. The ND group presented post-exercise hypotension (PEH) of systolic blood pressure and mean arterial pressure on the 90% LT session but T2D group did not. Plasma NOx increased ~24.4% for ND and ~13.8% for T2D group 15 min after the exercise session. Additionally, only ND individuals showed increases in PKA and BK in response to exercise and only T2D group showed increased DesArg(9)-BK production. It was concluded that T2D individuals presented lower PKA, BK and NOx release as well as higher DesArg(9)-BK production and reduced PEH in relation to ND participants after a single exercise session.

Type 2 Diabetes Elicits Lower Nitric Oxide, Bradykinin Concentration and Kallikrein Activity Together with Higher DesArg9-BK and Reduced Post-Exercise Hypotension Compared to Non-Diabetic Condition

PubMed Central

Browne, Rodrigo Alberto Vieira; Arsa, Gisela; Motta-Santos, Daisy; Puga, Guilherme Morais; Lima, Laila Cândida de Jesus; Campbell, Carmen Sílvia Grubert; Franco, Octavio Luiz

2013-01-01

This study compared the plasma kallikrein activity (PKA), bradykinin concentration (BK), DesArg9-BK production, nitric oxide release (NO) and blood pressure (BP) response after moderate-intensity aerobic exercise performed by individuals with and without type 2 diabetes. Ten subjects with type 2 diabetes (T2D) and 10 without type 2 diabetes (ND) underwent three sessions: 1) maximal incremental test on cycle ergometer to determine lactate threshold (LT); 2) 20-min of constant-load exercise on cycle ergometer, at 90% LT and; 3) control session. BP and oxygen uptake were measured at rest and at 15, 30 and 45 min post-exercise. Venous blood samples were collected at 15 and 45 minutes of the recovery period for further analysis of PKA, BK and DesArg9-BK. Nitrite plus nitrate (NOx) was analyzed at 15 minutes post exercise. The ND group presented post-exercise hypotension (PEH) of systolic blood pressure and mean arterial pressure on the 90% LT session but T2D group did not. Plasma NOx increased ~24.4% for ND and ~13.8% for T2D group 15min after the exercise session. Additionally, only ND individuals showed increases in PKA and BK in response to exercise and only T2D group showed increased DesArg9-BK production. It was concluded that T2D individuals presented lower PKA, BK and NOx release as well as higher DesArg9-BK production and reduced PEH in relation to ND participants after a single exercise session. PMID:24265812

High burden of BK virus-associated hemorrhagic cystitis in patients undergoing allogeneic hematopoietic stem cell transplantation.

PubMed

Gilis, L; Morisset, S; Billaud, G; Ducastelle-Leprêtre, S; Labussière-Wallet, H; Nicolini, F-E; Barraco, F; Detrait, M; Thomas, X; Tedone, N; Sobh, M; Chidiac, C; Ferry, T; Salles, G; Michallet, M; Ader, F

2014-05-01

BK virus (BKV) reactivation has been increasingly associated with the occurrence of late-onset hemorrhagic cystitis (HC) after allogeneic hematopoietic SCT (allo-HSCT) resulting in morbidity and sometimes mortality. We investigated the incidence, risk factors and outcome of BKV-HC in 323 consecutive adult patients undergoing allo-HSCT over a 5-year period. BK viremia values for HC staging were evaluated, as well as the medico-economic impact of the complication. Forty-three patients developed BKV-HC. In univariate analysis, young age (P=0.028), unrelated donor (P=0.0178), stem cell source (P=0.0001), HLA mismatching (P=0.0022) and BU in conditioning regimen (P=0.01) were associated with a higher risk of developing BKV-HC. In multivariate analysis, patients receiving cord blood units (CBUs) (P=0.0005) and peripheral blood stem cells (P=0.011) represented high-risk subgroups for developing BKV-HC. BK viremia was directly correlated to HC severity (P=0.011) with a 3 to 6-log peak being likely associated with grades 3 or 4 HC. No correlation was found between BKV-HC and acute graft versus host disease or mortality rate. Patients with BKV-HC required a significantly longer duration of hospitalization (P<0.0001), more RBC (P=0.0003) and platelet transfusions (P<0.0001). Over the 5-year study period, the financial cost of the complication was evaluated at \\[euro]2 376 076 ($3 088 899). Strategies to prevent the occurrence of late-onset BKV-HC after allo-HSCT are urgently needed, especially in CBU and peripheral blood stem cell recipients. BK viremia correlates with the severity of the disease. Prospective studies are required to test prophylactic approaches.

SLO BK Potassium Channels Couple Gap Junctions to Inhibition of Calcium Signaling in Olfactory Neuron Diversification.

PubMed

Alqadah, Amel; Hsieh, Yi-Wen; Schumacher, Jennifer A; Wang, Xiaohong; Merrill, Sean A; Millington, Grethel; Bayne, Brittany; Jorgensen, Erik M; Chuang, Chiou-Fen

2016-01-01

The C. elegans AWC olfactory neuron pair communicates to specify asymmetric subtypes AWCOFF and AWCON in a stochastic manner. Intercellular communication between AWC and other neurons in a transient NSY-5 gap junction network antagonizes voltage-activated calcium channels, UNC-2 (CaV2) and EGL-19 (CaV1), in the AWCON cell, but how calcium signaling is downregulated by NSY-5 is only partly understood. Here, we show that voltage- and calcium-activated SLO BK potassium channels mediate gap junction signaling to inhibit calcium pathways for asymmetric AWC differentiation. Activation of vertebrate SLO-1 channels causes transient membrane hyperpolarization, which makes it an important negative feedback system for calcium entry through voltage-activated calcium channels. Consistent with the physiological roles of SLO-1, our genetic results suggest that slo-1 BK channels act downstream of NSY-5 gap junctions to inhibit calcium channel-mediated signaling in the specification of AWCON. We also show for the first time that slo-2 BK channels are important for AWC asymmetry and act redundantly with slo-1 to inhibit calcium signaling. In addition, nsy-5-dependent asymmetric expression of slo-1 and slo-2 in the AWCON neuron is necessary and sufficient for AWC asymmetry. SLO-1 and SLO-2 localize close to UNC-2 and EGL-19 in AWC, suggesting a role of possible functional coupling between SLO BK channels and voltage-activated calcium channels in AWC asymmetry. Furthermore, slo-1 and slo-2 regulate the localization of synaptic markers, UNC-2 and RAB-3, in AWC neurons to control AWC asymmetry. We also identify the requirement of bkip-1, which encodes a previously identified auxiliary subunit of SLO-1, for slo-1 and slo-2 function in AWC asymmetry. Together, these results provide an unprecedented molecular link between gap junctions and calcium pathways for terminal differentiation of olfactory neurons.

Novel mechanism of hydrogen sulfide-induced guinea pig urinary bladder smooth muscle contraction: role of BK channels and cholinergic neurotransmission

PubMed Central

Fernandes, Vítor S.; Xin, Wenkuan

2015-01-01

Hydrogen sulfide (H2S) is a key signaling molecule regulating important physiological processes, including smooth muscle function. However, the mechanisms underlying H2S-induced detrusor smooth muscle (DSM) contractions are not well understood. This study investigates the cellular and tissue mechanisms by which H2S regulates DSM contractility, excitatory neurotransmission, and large-conductance voltage- and Ca2+-activated K+ (BK) channels in freshly isolated guinea pig DSM. We used a multidisciplinary experimental approach including isometric DSM tension recordings, colorimetric ACh measurement, Ca2+ imaging, and patch-clamp electrophysiology. In isolated DSM strips, the novel slow release H2S donor, P-(4-methoxyphenyl)-p-4-morpholinylphosphinodithioic acid morpholine salt (GYY4137), significantly increased the spontaneous phasic and nerve-evoked DSM contractions. The blockade of neuronal voltage-gated Na+ channels or muscarinic ACh receptors with tetrodotoxin or atropine, respectively, reduced the stimulatory effect of GYY4137 on DSM contractility. GYY4137 increased ACh release from bladder nerves, which was inhibited upon blockade of L-type voltage-gated Ca2+ channels with nifedipine. Furthermore, GYY4137 increased the amplitude of the Ca2+ transients and basal Ca2+ levels in isolated DSM strips. GYY4137 reduced the DSM relaxation induced by the BK channel opener, NS11021. In freshly isolated DSM cells, GYY4137 decreased the amplitude and frequency of transient BK currents recorded in a perforated whole cell configuration and reduced the single BK channel open probability measured in excised inside-out patches. GYY4137 inhibited spontaneous transient hyperpolarizations and depolarized the DSM cell membrane potential. Our results reveal the novel findings that H2S increases spontaneous phasic and nerve-evoked DSM contractions by activating ACh release from bladder nerves in combination with a direct inhibition of DSM BK channels. PMID:25948731

Vaccine for BK Polyomavirus-associated Infections in Transplant Recipients | NCI Technology Transfer Center | TTC

Cancer.gov

NCI researches identified a BK polyomavirus (BKV) virulent strain that causes chronic urinary tract infections, and the development of vaccine and therapeutic methods that would block BKV pathogenesis. The NCI Laboratory of Cellular Oncology, seek parties to license or co-develop this technology.

BK virus: opportunity makes a pathogen.

PubMed

Hirsch, Hans H

2005-08-01

More than 70% of the general population worldwide has serological evidence of exposure to Polyomavirus hominis type 1, better known as BK virus (BKV). BKV infection typically occurs during childhood, without specific symptoms, followed by a state of nonreplicative infection in various tissues, with the urogenital tract as the principal site. Asymptomatic reactivation and low-level replication with viruria is observed in 5% of healthy individuals. Persistent high-level BKV replication is the hallmark of polyomavirus-associated nephropathy in renal transplantation and of hemorrhagic cystitis in bone marrow transplantation. Since these manifestations are rare in other types of immunocompromised patients, the presence of specific cofactors is postulated. The role of BKV in autoimmune disease and cancer is a controversial topic and is difficult to determine, because the pathology no longer depends on BKV replication. This article discusses current views of pathogenesis, diagnosis, and treatment.

Unraveling hominin behavior at another anthropogenic site from Olduvai Gorge (Tanzania): new archaeological and taphonomic research at BK, Upper Bed II.

PubMed

Domínguez-Rodrigo, M; Mabulla, A; Bunn, H T; Barba, R; Diez-Martín, F; Egeland, C P; Espílez, E; Egeland, A; Yravedra, J; Sánchez, P

2009-09-01

New archaeological excavations and research at BK, Upper Bed II (Olduvai Gorge, Tanzania) have yielded a rich and unbiased collection of fossil bones. These new excavations show that BK is a stratified deposit formed in a riverine setting close to an alluvial plain. The present taphonomic study reveals the second-largest collection of hominin-modified bones from Olduvai, with abundant cut marks found on most of the anatomical areas preserved. Meat and marrow exploitation is reconstructed using the taphonomic signatures left on the bones by hominins. Highly cut-marked long limb shafts, especially those of upper limb bones, suggest that hominins at BK were actively engaged in acquiring small and middle-sized animals using strategies other than passive scavenging. The exploitation of large-sized game (Pelorovis) by Lower Pleistocene hominins, as suggested by previous researchers, is supported by the present study.

Full myeloablative conditioning and an unrelated HLA mismatched donor increase the risk for BK virus-positive hemorrhagic cystitis in allogeneic hematopoetic stem cell transplanted patients.

PubMed

Dalianis, Tina; Ljungman, Per

2011-03-01

BK virus (BKV)-associated hemorrhagic cystitis (HC), varying from mild hematuria with or without dysuria to life-threating bleeding and clots that may cause urinary obstruction and renal failure, causes significant morbidity and mortality in haematopoetic stem cell transplanted (HSCT) patients. Unfortunately, its development is difficult to predict since BK viruria is very common after HSCT and can be present in patients with and without HC. There is therefore the need to identify risk factors that may increase the risk of developing HC after HSCT. The viral load of BK-viruria, as well as BK viremia, has been monitored for this purpose. Moreover, having full myeoblative conditioning (MC) versus reduced intensity conditioning (RIC) prior to HSCT and an HLA-matched or -mismatched graft from an unrelated donor in contrast to an HLA-matched graft from a related donor have been studied as risk factors for HC. In addition, graft versus host disease has been examined, but has not been defined as a definite risk factor for HC. We conclude that the present evidence suggests that HSCT patients with BK viruria, receiving MC and an unrelated donor graft that is HLA-mismatched have an increased risk for developing HC in comparison to patients receiving RIC and an HLA-matched related donor graft.

Overexpression of the Large-Conductance, Ca2+-Activated K+ (BK) Channel Shortens Action Potential Duration in HL-1 Cardiomyocytes.

PubMed

Stimers, Joseph R; Song, Li; Rusch, Nancy J; Rhee, Sung W

2015-01-01

Long QT syndrome is characterized by a prolongation of the interval between the Q wave and the T wave on the electrocardiogram. This abnormality reflects a prolongation of the ventricular action potential caused by a number of genetic mutations or a variety of drugs. Since effective treatments are unavailable, we explored the possibility of using cardiac expression of the large-conductance, Ca2+-activated K+ (BK) channel to shorten action potential duration (APD). We hypothesized that expression of the pore-forming α subunit of human BK channels (hBKα) in HL-1 cells would shorten action potential duration in this mouse atrial cell line. Expression of hBKα had minimal effects on expression levels of other ion channels with the exception of a small but significant reduction in Kv11.1. Patch-clamped hBKα expressing HL-1 cells exhibited an outward voltage- and Ca2+-sensitive K+ current, which was inhibited by the BK channel blocker iberiotoxin (100 nM). This BK current phenotype was not detected in untransfected HL-1 cells or in HL-1 null cells sham-transfected with an empty vector. Importantly, APD in hBKα-expressing HL-1 cells averaged 14.3 ± 2.8 ms (n = 10), which represented a 53% reduction in APD compared to HL-1 null cells lacking BKα expression. APD in the latter cells averaged 31.0 ± 5.1 ms (n = 13). The shortened APD in hBKα-expressing cells was restored to normal duration by 100 nM iberiotoxin, suggesting that a repolarizing K+ current attributed to BK channels accounted for action potential shortening. These findings provide initial proof-of-concept that the introduction of hBKα channels into a cardiac cell line can shorten APD, and raise the possibility that gene-based interventions to increase hBKα channels in cardiac cells may hold promise as a therapeutic strategy for long QT syndrome.

Adjuvant Ciprofloxacin for Persistent BK Polyomavirus Infection in Kidney Transplant Recipients

PubMed Central

Chandran, Sindhu; Vagefi, Parsia A.

2014-01-01

Background. BK virus (BKV) infection is a common complication following kidney transplantation. Immunosuppression reduction is the cornerstone of treatment while adjuvant drugs have been tried in small uncontrolled studies. We sought to examine our center's experience with the use of ciprofloxacin in patients with persistent BKV infection. Methods. Retrospective evaluation of the effect of a 30-day ciprofloxacin course (250 mg twice daily) on BKV infection in kidney transplant recipients who had been diagnosed with BK viruria ≥106 copies/mL and viremia ≥500 copies/mL and in whom the infection did not resolve after immunosuppression reduction and/or treatment with other adjuvant agents. BKV in plasma and urine was evaluated after 3 months following treatment with ciprofloxacin. Results. Nine kidney transplant recipients received ciprofloxacin at a median of 130 days following the initial reduction in immunosuppression. Three patients showed complete viral clearance and another 3 had a ≥50% decrease in plasma viral load. No serious adverse events secondary to ciprofloxacin were reported and no grafts were lost due to BKV up to 1 year after treatment. Conclusion. Ciprofloxacin may be a useful therapy for persistent BKV infection despite conventional treatment. Randomized trials are required to evaluate the potential benefit of this adjuvant therapy. PMID:25349720

BK virus has tropism for human salivary gland cells in vitro: Implications for transmission

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeffers, Liesl K.; Madden, Vicki; Webster-Cyriaque, Jennifer, E-mail: jennifer@med.unc.ed

Background: In this study, it was determined that BKV is shed in saliva and an in vitro model system was developed whereby BKV can productively infect both submandibular (HSG) and parotid (HSY) salivary gland cell lines. Results: BKV was detected in oral fluids using quantitative real-time PCR (QRTPCR). BKV infection was determined using quantitative RT-PCR, immunofluorescence and immunoblotting assays. The infectivity of BKV was inhibited by pre-incubation of the virus with gangliosides that saturated the major capsid protein, VP1, halting receptor mediated BKV entry into salivary gland cells. Examination of infected cultures by transmission electron microscopy revealed 45-50 nm BKmore » virions clearly visible within the cells. Subsequent to infection, encapsidated BK virus was detected in the supernatant. Conclusion: We thus demonstrated that BKV was detected in oral fluids and that BK infection and replication occur in vitro in salivary gland cells. These data collectively suggest the potential for BKV oral route of transmission and oral pathogenesis.« less

Statin therapy exacerbates alcohol-induced constriction of cerebral arteries via modulation of ethanol-induced BK channel inhibition in vascular smooth muscle.

PubMed

Simakova, Maria N; Bisen, Shivantika; Dopico, Alex M; Bukiya, Anna N

2017-12-01

Statins constitute the most commonly prescribed drugs to decrease cholesterol (CLR). CLR is an important modulator of alcohol-induced cerebral artery constriction (AICAC). Using rats on a high CLR diet (2% CLR) we set to determine whether atorvastatin administration (10mg/kg daily for 18-23weeks) modified AICAC. Middle cerebral arteries were pressurized in vitro at 60mmHg and AICAC was evoked by 50mM ethanol, that is within the range of blood alcohol detected in humans following moderate-to-heavy drinking. AICAC was evident in high CLR+atorvastatin group but not in high CLR diet+placebo. Statin exacerbation of AICAC persisted in de-endothelialized arteries, and was blunted by CLR enrichment in vitro. Fluorescence imaging of filipin-stained arteries showed that atorvastatin decreased vascular smooth muscle (VSM) CLR when compared to placebo, this difference being reduced by CLR enrichment in vitro. Voltage- and calcium-gated potassium channels of large conductance (BK) are known VSM targets of ethanol, with their beta1 subunit being necessary for ethanol-induced channel inhibition and resulting AICAC. Ethanol-induced BK inhibition in excised membrane patches from freshly isolated myocytes was exacerbated in the high CLR diet+atorvastatin group when compared to high CLR diet+placebo. Unexpectedly, atorvastatin decreased the amount and function of BK beta1 subunit as documented by immunofluorescence imaging and functional patch-clamp studies. Atorvastatin exacerbation of ethanol-induced BK inhibition disappeared upon artery CLR enrichment in vitro. Our study demonstrates for the first time statin's ability to exacerbate the vascular effect of a widely consumed drug of abuse, this exacerbation being driven by statin modulation of ethanol-induced BK channel inhibition in the VSM via CLR-mediated mechanism. Copyright © 2017 Elsevier Inc. All rights reserved.

Structural Determinants for Functional Coupling Between the β and α Subunits in the Ca2+-activated K+ (BK) Channel

PubMed Central

Orio, Patricio; Torres, Yolima; Rojas, Patricio; Carvacho, Ingrid; Garcia, Maria L.; Toro, Ligia; Valverde, Miguel A.; Latorre, Ramon

2006-01-01

High conductance, calcium- and voltage-activated potassium (BK, MaxiK) channels are widely expressed in mammals. In some tissues, the biophysical properties of BK channels are highly affected by coexpression of regulatory (β) subunits. The most remarkable effects of β1 and β2 subunits are an increase of the calcium sensitivity and the slow down of channel kinetics. However, the detailed characteristics of channels formed by α and β1 or β2 are dissimilar, the most remarkable difference being a reduction of the voltage sensitivity in the presence of β1 but not β2. Here we reveal the molecular regions in these β subunits that determine their differential functional coupling with the pore-forming α-subunit. We made chimeric constructs between β1 and β2 subunits, and BK channels formed by α and chimeric β subunits were expressed in Xenopus laevis oocytes. The electrophysiological characteristics of the resulting channels were determined using the patch clamp technique. Chimeric exchange of the different regions of the β1 and β2 subunits demonstrates that the NH3 and COOH termini are the most relevant regions in defining the behavior of either subunit. This strongly suggests that the intracellular domains are crucial for the fine tuning of the effects of these β subunits. Moreover, the intracellular domains of β1 are responsible for the reduction of the BK channel voltage dependence. This agrees with previous studies that suggested the intracellular regions of the α-subunit to be the target of the modulation by the β1-subunit. PMID:16446507

Characterization of an extracellular lipase by Pseudomonas koreensis BK-L07 isolated from soil.

PubMed

Anbu, Periasamy

2014-01-01

Screening using spirit blue agar revealed that strain BK-L07 had the highest lipase activity. Furthermore, the isolated strain was identified as Pseudomonas sp. based on morphological, physiological, biochemical, and molecular analyses. The 16S rRNA gene sequence of strain BK-L07 shared a high similarity with that of Pseudomonas koreensis (99%). The nutritional conditions and physicochemical properties were influenced by P. koreensis BK-L07. The maximum lipase production was obtained in tryptic soy broth medium at pH 8.0 and a temperature of 25°C after 36 hr of incubation. In addition, the lipase activity was determined using different carbon sources and lipase inducers. The lipase production was greatest when 1% maltose was used as the carbon source and olive oil was used as the lipase inducer. The lipase production was significantly increased approximately threefold in the optimized medium when compared with the original medium. Further, the lipase was purified by ammonium sulfate precipitation and gel filtration chromatography with a purification yield of 10.8%. The molecular mass of lipase was 45 kDa. The optimum temperature and pH were 40°C and 8.0, respectively. The enzyme was stable up to 50°C and at pH from 7 to 9. In addition, the enzyme activity was stimulated by MgSO4 and completely inhibited by ethylenediamine tetraacetic acid (EDTA), indicating the metalloenzyme type. The lipase activity was toward medium to long chain length of fatty acids (C10 to C18). Supplemental materials are available for this article. Go to the publisher's online edition of Preparative Biochemistry and Biotechnology to view the supplemental file.

Hemorrhagic cystitis and possible neurologic disease from BK virus infection in a patient with AIDS.

PubMed

Kinnaird, A N; Anstead, G M

2010-04-01

BK virus (BKV)-associated hemorrhagic cystitis occurs in bone marrow transplant recipients but is rare among other immunosuppressed patients. We present a rare case of BKV-associated hemorrhagic cystitis in a 48-year-old man with AIDS and previously diagnosed progressive multifocal leukoencephalopathy.

Critical role for cochlear hair cell BK channels for coding the temporal structure and dynamic range of auditory information for central auditory processing

PubMed Central

Kurt, Simone; Sausbier, Matthias; Rüttiger, Lukas; Brandt, Niels; Moeller, Christoph K.; Kindler, Jennifer; Sausbier, Ulrike; Zimmermann, Ulrike; van Straaten, Harald; Neuhuber, Winfried; Engel, Jutta; Knipper, Marlies; Ruth, Peter; Schulze, Holger

2012-01-01

Large conductance, voltage- and Ca2+-activated K+ (BK) channels in inner hair cells (IHCs) of the cochlea are essential for hearing. However, germline deletion of BKα, the pore-forming subunit KCNMA1 of the BK channel, surprisingly did not affect hearing thresholds in the first postnatal weeks, even though altered IHC membrane time constants, decreased IHC receptor potential alternating current/direct current ratio, and impaired spike timing of auditory fibers were reported in these mice. To investigate the role of IHC BK channels for central auditory processing, we generated a conditional mouse model with hair cell-specific deletion of BKα from postnatal day 10 onward. This had an unexpected effect on temporal coding in the central auditory system: neuronal single and multiunit responses in the inferior colliculus showed higher excitability and greater precision of temporal coding that may be linked to the improved discrimination of temporally modulated sounds observed in behavioral training. The higher precision of temporal coding, however, was restricted to slower modulations of sound and reduced stimulus-driven activity. This suggests a diminished dynamic range of stimulus coding that is expected to impair signal detection in noise. Thus, BK channels in IHCs are crucial for central coding of the temporal fine structure of sound and for detection of signals in a noisy environment.—Kurt, S., Sausbier, M., Rüttiger, L., Brandt, N., Moeller, C. K., Kindler, J., Sausbier, U., Zimmermann, U., van Straaten, H., Neuhuber, W., Engel, J., Knipper, M., Ruth, P., Schulze, H. Critical role for cochlear hair cell BK channels for coding the temporal structure and dynamic range of auditory information for central auditory processing. PMID:22691916

Properties of optical breakdown in BK7 glass induced by an extended-cavity femtosecond laser oscillator.

PubMed

Do, Binh T; Phillips, Mark C; Miller, Paul A; Kimmel, Mark W; Britsch, Justin; Cho, Seong-Ho

2009-02-16

Using an extended-cavity femtosecond oscillator, we investigated optical breakdown in BK7 glass caused by the accumulated action of many laser pulses. By using a pump-probe experiment and collecting the transmitted pump along with the reflected pump and the broadband light generated by the optical breakdown, we measured the build-up time to optical breakdown as a function of the pulse energy, and we also observed the instability of the plasma due to the effect of defocusing and shielding created by the electron gas. The spectrum of the broadband light emitted by the optical breakdown and the origin of the material modification in BK7 glass was studied. We developed a simple model of electromagnetic wave propagation in plasma that is consistent with the observed behavior of the reflection, absorption, and transmission of the laser light.

Different behaviour of BK-virus infection in liver transplant recipients

PubMed Central

Umbro, Ilaria; Tinti, Francesca; Muiesan, Paolo; Mitterhofer, Anna Paola

2016-01-01

Polyomavirus BK (BKV) infects up to 90% of the general population. After primary infection, occurring early during childhood, a state of non-replicative infection is established in the reno-urinary tract, without complications for immunocompetent hosts. In immunocompromised individuals, particularly transplanted patients, asymptomatic BKV viremia and/or viruria can be observed. Renal grafts may also be sources of infection as BKV prefers kidneys rather than other solid organs for transplantation such as the liver. The mechanism behind the higher incidence of BKV infection in kidney transplant patients, compared to liver or heart transplantation, is unclear and the prevalence of BKV infection in non-renal solid organ transplants has not been yet thoroughly investigated. We evaluated the prevalence of Polyomavirus BK infection among liver transplant recipients. A PubMed search was conducted using the terms BKV infection AND liver transplant recipients; BKV AND non-renal solid organ transplant*; BKV infection AND immunosuppression; the search was limited to title/abstract and English-language articles published from 2000, to March 2015. Eleven relevant studies suggest that the prevalence of BKV viruria and/or viremia among liver transplant recipients is less than that reported in kidney or heart transplant recipients, except when chronic kidney disease (CKD) is present at the same time. Data also suggest that viruric and viremic patients have higher levels of serum creatinine than BKV negative patients. Moreover, no specific immunosuppressive drugs are associated with the onset of BKV nephropathy. The comorbidity of transplantation and CKD could play a major role in promoting BKV replication. PMID:26819520

BK virus associated pronounced hemorrhagic cystoureteritis after bone marrow transplantation.

PubMed

Haab, Alexander C; Keller, Isabelle S; Padevit, Christian; John, Hubert

2015-10-01

Ureteral stenosis due to reactivation of the BK virus (BKV) in a state of immunodeficiency is very rare. More common is the appearance of a hemorrhagic cystitis. This report not only shows bilateral ureteral stenosis after bone marrow transplantation, but also presents severe complications as chronic pelvic pain and impaired kidney function as well as irreparable damage to the whole urinary tract leading to nephroureterectomy, subtrigonal cystectomy and orthotopic ileal neobladder. Finally renal transplantation was required. To our knowledge this is the first case in the literature where such a severe course of BKV associated hemorrhagic cystoureteritis is described.

BK-virus nephropathy and simultaneous C4d positive staining in renal allografts.

PubMed

Honsová, E; Lodererová, A; Viklický, O; Boucek, P

2005-10-01

The role of antibodies in rejection of transplanted kidneys was the subject of debate at the last two Banff meetings and in medical journals. Diffuse C4d positive staining of peritubular capillaries (PTCs) was recognized as a marker of antibody-mediated rejection and this morphological feature was included in the updated Banff schema. At the same time polyomavirus infection of the renal allografts has been reported more frequently and is emerging as an important cause of renal allograft dysfunction and graft loss. At the present time, BK-virus nephropathy (BKN) represents the most common viral disease affecting renal allografts. BKN was identified in 6 patients in 12 biopsies and 2 graft nephrectomy specimens of 1115 biopsies between September 2000 and December 2003. Definite virus identification was done by immunohistochemistry. The reason for graft nephrectomies was graft failure due to BKN in a recipient after kidney-pancreas transplantation with good function of his pancreas graft and the necessity of continuing immunosuppression. Detection of C4d deposits was performed by immunofluorescence or by immunohistochemistry. In graftectomy samples C4d detection was performed by immunohistochemistry and retrospectively in all cases of BKN. Focal C4d positive PTCs and BKN were found simultaneously in 9 of 12 needle biopsies and in both graft nephrectomy samples. Detection of C4d by immunohistochemistry disclosed focal C4d positive staining in kidney tissue but diffuse in the sites where BK-virus inclusions in tubular epithelial cells were found. The complement system is part of the host defense response and is crucial to our natural ability to ward off infection. In cases of BKN, virus likely gains access to the bloodstream through injured tubular walls and via PTCs. Vascular endothelium in the PTCs represents a potential target antigen for alloresponse, and simultaneously possibly represents an imprint of complement activation or complement production in the places

A New Splice Variant of Large Conductance Ca2+-activated K+ (BK) Channel α Subunit Alters Human Chondrocyte Function.

PubMed

Suzuki, Yoshiaki; Ohya, Susumu; Yamamura, Hisao; Giles, Wayne R; Imaizumi, Yuji

2016-11-11

Large conductance Ca 2+ -activated K + (BK) channels play essential roles in both excitable and non-excitable cells. For example, in chondrocytes, agonist-induced Ca 2+ release from intracellular store activates BK channels, and this hyperpolarizes these cells, augments Ca 2+ entry, and forms a positive feed-back mechanism for Ca 2+ signaling and stimulation-secretion coupling. In the present study, functional roles of a newly identified splice variant in the BK channel α subunit (BKαΔe2) were examined in a human chondrocyte cell line, OUMS-27, and in a HEK293 expression system. Although BKαΔe2 lacks exon2, which codes the intracellular S0-S1 linker (Glu-127-Leu-180), significant expression was detected in several tissues from humans and mice. Molecular image analyses revealed that BKαΔe2 channels are not expressed on plasma membrane but can traffic to the plasma membrane after forming hetero-tetramer units with wild-type BKα (BKαWT). Single-channel current analyses demonstrated that BKα hetero-tetramers containing one, two, or three BKαΔe2 subunits are functional. These hetero-tetramers have a smaller single channel conductance and exhibit lower trafficking efficiency than BKαWT homo-tetramers in a stoichiometry-dependent manner. Site-directed mutagenesis of residues in exon2 identified Helix2 and the linker to S1 (Trp-158-Leu-180, particularly Arg-178) as an essential segment for channel function including voltage dependence and trafficking. BKαΔe2 knockdown in OUMS-27 chondrocytes increased BK current density and augmented the responsiveness to histamine assayed as cyclooxygenase-2 gene expression. These findings provide significant new evidence that BKαΔe2 can modulate cellular responses to physiological stimuli in human chondrocyte and contribute under pathophysiological conditions, such as osteoarthritis. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

The Role of Ca2+ and BK Channels of Locus Coeruleus (LC) Neurons as a Brake to the CO2 Chemosensitivity Response of Rats.

PubMed

Imber, Ann N; Patrone, Luis G A; Li, Ke-Yong; Gargaglioni, Luciane H; Putnam, Robert W

2018-06-15

The cellular mechanisms by which LC neurons respond to hypercapnia are usually attributed to an "accelerator" whereby hypercapnic acidosis causes an inhibition of K + channels or activation of Na + and Ca +2 channels to depolarize CO 2 -sensitive neurons. Nevertheless, it is still unknown if this "accelerator" mechanism could be controlled by a brake phenomenon. Whole-cell patch clamping, fluorescence imaging microscopy and plethysmography were used to study the chemosensitive response of the LC neurons. Hypercapnic acidosis activates L-type Ca 2+ channels and large conductance Ca-activated K + (BK) channels, which function as a "brake" on the chemosensitive response of LC neurons. Our findings indicate that both Ca 2+ and BK currents develop over the first 2 weeks of postnatal life in rat LC slices and that this brake pathway may cause the developmental decrease in the chemosensitive firing rate response of LC neurons to hypercapnic acidosis. Inhibition of this brake by paxilline (BK channel inhibitor) returns the magnitude of the chemosensitive firing rate response from LC neurons in rats older than P10 to high values similar to those in LC neurons from younger rats. Inhibition of BK channels in LC neurons by bilateral injections of paxilline into the LC results in a significant increase in the hypercapnic ventilatory response of adult rats. Our findings indicate that a BK channel-based braking system helps to determine the chemosensitive respiratory drive of LC neurons and contributes to the hypercapnic ventilatory response. Perhaps, abnormalities of this braking system could result in hypercapnia-induced respiratory disorders and panic responses. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.

Cytomegalovirus and polyomavirus BK posttransplant.

PubMed

Egli, Adrian; Binggeli, Simone; Bodaghi, Sohrab; Dumoulin, Alexis; Funk, Georg A; Khanna, Nina; Leuenberger, David; Gosert, Rainer; Hirsch, Hans H

2007-09-01

Virus replication and progression to disease in transplant patients is determined by patient-, graft- and virus-specific factors. This complex interaction is modulated by the net state of immunosuppression and its impact on virus-specific cellular immunity. Due to the increasing potency of immunosuppressive regimens, graft rejections have decreased, but susceptibility to infections has increased. Therefore, cytomegalovirus (CMV) remains the most important viral pathogen posttransplant despite availability of effective antiviral drugs and validated strategies for prophylactic, preemptive and therapeutic intervention. CMV replication can affect almost every organ system, with frequent recurrences and increasing rates of antiviral resistance. Together with indirect long-term effects, CMV significantly reduces graft and patient survival after solid organ and hematopoietic stem cell transplantation. The human polyomavirus called BK virus (BKV), on the other hand, only recently surfaced as pathogen with organ tropism largely limited to the reno-urinary tract, manifesting as polyomavirus-associated nephropathy in kidney transplant and hemorrhagic cystitis in hematopoetic stem cell transplant patients. No licensed anti-polyoma viral drugs are available, and treatment relies mainly on improving immune functions to regain control over BKV replication. In this review, we discuss diagnostic and therapeutic aspects of CMV and BKV replication and disease posttransplantation.

An EP2 Agonist Facilitates NMDA-Induced Outward Currents and Inhibits Dendritic Beading through Activation of BK Channels in Mouse Cortical Neurons

PubMed Central

Hayashi, Yoshinori; Morinaga, Saori; Liu, Xia; Zhang, Jing; Wu, Zhou; Yokoyama, Takeshi; Nakanishi, Hiroshi

2016-01-01

Prostaglandin E2 (PGE2), a major metabolite of arachidonic acid produced by cyclooxygenase pathways, exerts its bioactive responses by activating four E-prostanoid receptor subtypes, EP1, EP2, EP3, and EP4. PGE2 enables modulating N-methyl-D-aspartate (NMDA) receptor-mediated responses. However, the effect of E-prostanoid receptor agonists on large-conductance Ca2+-activated K+ (BK) channels, which are functionally coupled with NMDA receptors, remains unclear. Here, we showed that EP2 receptor-mediated signaling pathways increased NMDA-induced outward currents (I NMDA-OUT), which are associated with the BK channel activation. Patch-clamp recordings from the acutely dissociated mouse cortical neurons revealed that an EP2 receptor agonist activated I NMDA-OUT, whereas an EP3 receptor agonist reduced it. Agonists of EP1 or EP4 receptors showed no significant effects on I NMDA-OUT. A direct perfusion of 3,5′-cyclic adenosine monophosphate (cAMP) through the patch pipette facilitated I NMDA-OUT, which was abolished by the presence of protein kinase A (PKA) inhibitor. Furthermore, facilitation of I NMDA-OUT caused by an EP2 receptor agonist was significantly suppressed by PKA inhibitor. Finally, the activation of BK channels through EP2 receptors facilitated the recovery phase of NMDA-induced dendritic beading in the primary cultured cortical neurons. These results suggest that a direct activation of BK channels by EP2 receptor-mediated signaling pathways plays neuroprotective roles in cortical neurons. PMID:27298516

Interactions of divalent cations with calcium binding sites of BK channels reveal independent motions within the gating ring.

PubMed

Miranda, Pablo; Giraldez, Teresa; Holmgren, Miguel

2016-12-06

Large-conductance voltage- and calcium-activated K + (BK) channels are key physiological players in muscle, nerve, and endocrine function by integrating intracellular Ca 2+ and membrane voltage signals. The open probability of BK channels is regulated by the intracellular concentration of divalent cations sensed by a large structure in the BK channel called the "gating ring," which is formed by four tandems of regulator of conductance for K + (RCK1 and RCK2) domains. In contrast to Ca 2+ that binds to both RCK domains, Mg 2+ , Cd 2+ , or Ba 2+ interact preferentially with either one or the other. Interaction of cations with their binding sites causes molecular rearrangements of the gating ring, but how these motions occur remains elusive. We have assessed the separate contributions of each RCK domain to the cation-induced gating-ring structural rearrangements, using patch-clamp fluorometry. Here we show that Mg 2+ and Ba 2+ selectively induce structural movement of the RCK2 domain, whereas Cd 2+ causes motions of RCK1, in all cases substantially smaller than those elicited by Ca 2+ By combining divalent species interacting with unique sites, we demonstrate that RCK1 and RCK2 domains move independently when their specific binding sites are occupied. Moreover, binding of chemically distinct cations to both RCK domains is additive, emulating the effect of fully occupied Ca 2+ binding sites.

BK Channel-Mediated Relaxation of Urinary Bladder Smooth Muscle: A Novel Paradigm for Phosphodiesterase Type 4 Regulation of Bladder Function

PubMed Central

Xin, Wenkuan; Li, Ning; Cheng, Qiuping

2014-01-01

Elevation of intracellular cAMP and activation of protein kinase A (PKA) lead to activation of large conductance voltage- and Ca2+-activated K+ (BK) channels, thus attenuation of detrusor smooth muscle (DSM) contractility. In this study, we investigated the mechanism by which pharmacological inhibition of cAMP-specific phosphodiesterase 4 (PDE4) with rolipram or Ro-20-1724 (C15H22N2O3) suppresses guinea pig DSM excitability and contractility. We used high-speed line-scanning confocal microscopy, ratiometric fluorescence Ca2+ imaging, and perforated whole-cell patch-clamp techniques on freshly isolated DSM cells, along with isometric tension recordings of DSM isolated strips. Rolipram caused an increase in the frequency of Ca2+ sparks and the spontaneous transient BK currents (TBKCs), hyperpolarized the cell membrane potential (MP), and decreased the intracellular Ca2+ levels. Blocking BK channels with paxilline reversed the hyperpolarizing effect of rolipram and depolarized the MP back to the control levels. In the presence of H-89 [N-[2-[[3-(4-bromophenyl)-2-propenyl]amino]ethyl]-5-isoquinolinesulfonamide dihydrochloride], a PKA inhibitor, rolipram did not cause MP hyperpolarization. Rolipram or Ro-20-1724 reduced DSM spontaneous and carbachol-induced phasic contraction amplitude, muscle force, duration, and frequency, and electrical field stimulation-induced contraction amplitude, muscle force, and tone. Paxilline recovered DSM contractility, which was suppressed by pretreatment with PDE4 inhibitors. Rolipram had reduced inhibitory effects on DSM contractility in DSM strips pretreated with paxilline. This study revealed a novel cellular mechanism whereby pharmacological inhibition of PDE4 leads to suppression of guinea pig DSM contractility by increasing the frequency of Ca2+ sparks and the functionally coupled TBKCs, consequently hyperpolarizing DSM cell MP. Collectively, this decreases the global intracellular Ca2+ levels and DSM contractility in a BK channel

Mechanism of the modulation of BK potassium channel complexes with different auxiliary subunit compositions by the omega-3 fatty acid DHA.

PubMed

Hoshi, Toshinori; Tian, Yutao; Xu, Rong; Heinemann, Stefan H; Hou, Shangwei

2013-03-19

Large-conductance Ca(2+)- and voltage-activated K(+) (BK) channels are well known for their functional versatility, which is bestowed in part by their rich modulatory repertoire. We recently showed that long-chain omega-3 polyunsaturated fatty acids such as docosahexaenoic acid (DHA) found in oily fish lower blood pressure by activating vascular BK channels made of Slo1+β1 subunits. Here we examined the action of DHA on BK channels with different auxiliary subunit compositions. Neuronal Slo1+β4 channels were just as well activated by DHA as vascular Slo1+β1 channels. In contrast, the stimulatory effect of DHA was much smaller in Slo1+β2, Slo1+LRRC26 (γ1), and Slo1 channels without auxiliary subunits. Mutagenesis of β1, β2, and β4 showed that the large effect of DHA in Slo1+β1 and Slo1+β4 is conferred by the presence of two residues, one in the N terminus and the other in the first transmembrane segment of the β1 and β4 subunits. Transfer of this amino acid pair from β1 or β4 to β2 introduces a large response to DHA in Slo1+β2. The presence of a pair of oppositely charged residues at the aforementioned positions in β subunits is associated with a large response to DHA. The Slo1 auxiliary subunits are expressed in a highly tissue-dependent fashion. Thus, the subunit composition-dependent stimulation by DHA demonstrates that BK channels are effectors of omega-3 fatty acids with marked tissue specificity.

Hemorrhagic cystitis after allogeneic hematopoietic stem cell transplants is the complex result of BK virus infection, preparative regimen intensity and donor type

PubMed Central

de Padua Silva, Leandro; Patah, Poliana A.; Saliba, Rima M.; Szewczyk, Nicholas A.; Gilman, Lisa; Neumann, Joyce; Han, Xiang-Yang; Tarrand, Jeffrey; Ribeiro, Rachel; Gulbis, Alison; Shpall, Elizabeth J.; Jones, Roy; Popat, Uday; Walker, Julia A.; Petropoulos, Demetrios; Chiattone, Alexandre; Stewart, John; El-Zimaity, Maha; Anderlini, Paolo; Giralt, Sergio; Champlin, Richard E; de Lima, Marcos

2010-01-01

Background Hemorrhagic cystitis is a common cause of morbidity after allogeneic stem cell transplantation, frequently associated with BK virus infection. We hypothesized that patients with positive BK viruria before unrelated or mismatched related donor allogeneic hematopoietic stem cell transplantation have a higher incidence of hemorrhagic cystitis. Design and Methods To test this hypothesis, we prospectively studied 209 patients (median age 49 years, range 19–71) with hematologic malignancies who received bone marrow (n=78), peripheral blood (n=108) or umbilical cord blood (n=23) allogeneic hematopoietic stem cell transplantation after myeloablative (n=110) or reduced intensity conditioning (n=99). Donors were unrelated (n=201) or haploidentical related (n=8). Results Twenty-five patients developed hemorrhagic cystitis. Pre-transplant BK viruria detected by quantitative PCR was positive in 96 patients. The one-year cumulative incidence of hemorrhagic cystitis was 16% in the PCR-positive group versus 9% in the PCR-negative group (P=0.1). The use of umbilical cord blood or a haploidentical donor was the only significant predictor of the incidence of hemorrhagic cystitis on univariate analysis. There was also a trend for a higher incidence after myeloablative conditioning. Multivariate analysis showed that patients who had a positive PCR pre-transplant and received haploidentical or cord blood grafts with myeloablative conditioning had a significantly higher risk of developing hemorrhagic cystitis (58%) than all other recipients (7%, P<0.001). Conclusions Hemorrhagic cystitis is the result of a complex interaction of donor type, preparative regimen intensity, and BK viruria. PMID:20410183

Inhibitory action of ICI-182,780, an estrogen receptor antagonist, on BK(Ca) channel activity in cultured endothelial cells of human coronary artery.

PubMed

Liu, Yen-Chin; Lo, Yi-Ching; Huang, Chin-Wei; Wu, Sheng-Nan

2003-11-15

ICI-182,780 is known to be a selective inhibitor of the intracellular estrogen receptors. The effect of ICI-182,780 on ion currents was studied in cultured endothelial cells of human coronary artery. In whole-cell current recordings, ICI-182,780 reversibly decreased the amplitude of K(+) outward currents. The decrease in outward current caused by ICI-182,780 could be counteracted by further application of magnolol or nordihydroguaiaretic acid, yet not by 17beta-estradiol. Under current-clamp condition, ICI-182,780 (3microM) depolarized the membrane potentials of the cells, and magnolol (10 microM) or nordihydroguaiaretic acid (10 microM) reversed ICI-182,780-induced depolarization. In inside-out patches, ICI-182,780 added to the bath did not alter single-channel conductance of large-conductance Ca(2+)-activated K(+) channels (BK(Ca) channels), but decreased their open probability. ICI-182,780 reduced channel activity in a concentration-dependent manner with an IC(50) value of 3 microM. After BK(Ca) channel activity was suppressed by 2-methoxyestradiol (3 microM), subsequent application of ICI-182,780 (3 microM) did not further reduce the channel activity. The application of ICI-182,780 shifted the activation curve of BK(Ca) channels to positive potentials. Its decrease in the open probability primarily involved a reduction in channel open duration. ICI-182,780 also suppressed the proliferation of these endothelial cells with an IC(50) value of 2 microM. However, in coronary smooth muscle cells, a bell-shaped concentration-response curve for the ICI-182,780 effect on BK(Ca) channel activity was observed. This study provides evidence that ICI-182,780 can inhibit BK(Ca) channels in vascular endothelial cells in a mechanism unlikely to be linked to its anti-estrogen activity. The inhibitory effects on these channels may partly contribute to the underlying mechanisms by which ICI-182,780 affects endothelial function.

Oxidative Stress and Maxi Calcium-Activated Potassium (BK) Channels

PubMed Central

Hermann, Anton; Sitdikova, Guzel F.; Weiger, Thomas M.

2015-01-01

All cells contain ion channels in their outer (plasma) and inner (organelle) membranes. Ion channels, similar to other proteins, are targets of oxidative impact, which modulates ion fluxes across membranes. Subsequently, these ion currents affect electrical excitability, such as action potential discharge (in neurons, muscle, and receptor cells), alteration of the membrane resting potential, synaptic transmission, hormone secretion, muscle contraction or coordination of the cell cycle. In this chapter we summarize effects of oxidative stress and redox mechanisms on some ion channels, in particular on maxi calcium-activated potassium (BK) channels which play an outstanding role in a plethora of physiological and pathophysiological functions in almost all cells and tissues. We first elaborate on some general features of ion channel structure and function and then summarize effects of oxidative alterations of ion channels and their functional consequences. PMID:26287261

Conversion from tacrolimus-mycophenolate mofetil to tacrolimus-mTOR immunosuppression after kidney-pancreas transplantation reduces the incidence of both BK and CMV viremia.

PubMed

Knight, Richard J; Graviss, Edward A; Nguyen, Duc T; Kuten, Samantha A; Patel, Samir J; Gaber, Lillian; Gaber, A Osama

2018-04-19

We sought to determine whether conversion from tacrolimus/mycophenolate mofetil (TAC-MMF) into tacrolimus/mTOR inhibitor (TAC-mTOR) immunosuppression would reduce the incidences of BK and CMV viremia after kidney/pancreas (KP) transplantation. In this single-center review, the TAC-mTOR cohort (n = 39) was converted at 1 month post-transplant to an mTOR inhibitor and reduced-dose tacrolimus. Outcomes were compared to a cohort of KP recipients (n = 40) maintained on TAC-MMF. At 3 years post-transplant, KP survivals and incidences of kidney/pancreas rejection were equivalent between mTOR and MMF-treated cohorts. (P = ns). BK viremia-free survival was better for the mTOR vs MMF-treated group (P = .004). In multivariate analysis, MMF vs mTOR immunosuppression was an independent risk factor for BK viremia (hazard ratio 12.27, P = .02). Similarly, mTOR-treated recipients displayed better CMV infection-free survival compared to the MMF-treated cohort (P = .01). MMF vs mTOR immunosuppression (hazard ratio 18.77, P = .001) and older recipient age (hazard ratio 1.13 per year, P = .006) were independent risk factors for CMV viremia. Mean estimated GFR and HgbA1c levels were equivalent between groups at 1, 2, and 3 years post-transplantation. Conversion from TAC/MMF into TAC/mTOR immunosuppression after KP transplantation reduced the incidences of BK and CMV viremia with an equivalent risk of acute rejection and similar renal/pancreas function. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Detection of BK virus and adenovirus in the urine from children after allogeneic stem cell transplantation.

PubMed

Hatakeyama, Naoki; Suzuki, Nobuhiro; Yamamoto, Masaki; Kuroiwa, Yuki; Hori, Tsukasa; Mizue, Nobuo; Tsutsumi, Hiroyuki

2006-01-01

The development of hemorrhagic cystitis (HC) and urinary excretion of polyoma BK virus (BKV) and adenovirus (ADV) was investigated by polymerase chain reaction in 20 children undergoing allogeneic stem cell transplantation. Five children developed HC, and all of them excreted BKV; however, only 1 excreted ADV, suggesting that BKV is more significant cause of HC than ADV in children undergoing stem cell transplantation.

Abnormal differentiation, hyperplasia and embryonic/perinatal lethality in BK5-T/t transgenic mice

PubMed Central

Chen, Xin; Schneider-Broussard, Robin; Hollowell, Debra; McArthur, Mark; Jeter, Collene R.; Benavides, Fernando; DiGiovanni, John; Tang, Dean G.

2009-01-01

The cell-of-origin has a great impact on the types of tumors that develop and the stem/progenitor cells have long been considered main targets of malignant transformation. The SV40 large T and small t antigens (T/t), have been targeted to multiple differentiated cellular compartments in transgenic mice. In most of these studies, transgenic animals develop tumors without apparent defects in animal development. In this study, we used the bovine keratin 5 (BK5) promoter to target the T/t antigens to stem/progenitor cell-containing cytokeratin 5 (CK5) cellular compartment. A transgene construct, BK5-T/t, was made and microinjected into the male pronucleus of FVB/N mouse oocytes. After implanting ∼1700 embryos, only 7 transgenics were obtained, including 4 embryos (E9.5, E13, E15, and E20) and 3 postnatal animals, which died at P1, P2, and P18, respectively. Immunohistological analysis revealed aberrant differentiation and prominent hyperplasia in several transgenic CK5 tissues, especially the upper digestive organs (tongue, oral mucosa, esophagus, and forestomach) and epidermis, the latter of which also showed focal dysplasia. Altogether, these results indicate that constitutive expression of the T/t antigens in CK5 cellular compartment results in abnormal epithelial differentiation and leads to embryonic/perinatal animal lethality. PMID:19272531

Experimental Investigation on Cutting Characteristics in Nanometric Plunge-Cutting of BK7 and Fused Silica Glasses

PubMed Central

An, Qinglong; Ming, Weiwei; Chen, Ming

2015-01-01

Ductile cutting are most widely used in fabricating high-quality optical glass components to achieve crack-free surfaces. For ultra-precision machining of brittle glass materials, critical undeformed chip thickness (CUCT) commonly plays a pivotal role in determining the transition point from ductile cutting to brittle cutting. In this research, cutting characteristics in nanometric cutting of BK7 and fused silica glasses, including machined surface morphology, surface roughness, cutting force and specific cutting energy, were investigated with nanometric plunge-cutting experiments. The same cutting speed of 300 mm/min was used in the experiments with single-crystal diamond tool. CUCT was determined according to the mentioned cutting characteristics. The results revealed that 320 nm was found as the CUCT in BK7 cutting and 50 nm was determined as the size effect of undeformed chip thickness. A high-quality machined surface could be obtained with the undeformed chip thickness between 50 and 320 nm at ductile cutting stage. Moreover, no CUCT was identified in fused silica cutting with the current cutting conditions, and brittle-fracture mechanism was confirmed as the predominant chip-separation mode throughout the nanometric cutting operation. PMID:28788010

Experimental Investigation on Cutting Characteristics in Nanometric Plunge-Cutting of BK7 and Fused Silica Glasses.

PubMed

An, Qinglong; Ming, Weiwei; Chen, Ming

2015-03-27

Ductile cutting are most widely used in fabricating high-quality optical glass components to achieve crack-free surfaces. For ultra-precision machining of brittle glass materials, critical undeformed chip thickness (CUCT) commonly plays a pivotal role in determining the transition point from ductile cutting to brittle cutting. In this research, cutting characteristics in nanometric cutting of BK7 and fused silica glasses, including machined surface morphology, surface roughness, cutting force and specific cutting energy, were investigated with nanometric plunge-cutting experiments. The same cutting speed of 300 mm/min was used in the experiments with single-crystal diamond tool. CUCT was determined according to the mentioned cutting characteristics. The results revealed that 320 nm was found as the CUCT in BK7 cutting and 50 nm was determined as the size effect of undeformed chip thickness. A high-quality machined surface could be obtained with the undeformed chip thickness between 50 and 320 nm at ductile cutting stage. Moreover, no CUCT was identified in fused silica cutting with the current cutting conditions, and brittle-fracture mechanism was confirmed as the predominant chip-separation mode throughout the nanometric cutting operation.

Symptomatic BK Virus Infection Is Associated with Kidney Function Decline and Poor Overall Survival in Allogeneic Hematopoietic Stem Cell Recipients

PubMed Central

Abudayyeh, Ala; Hamdi, Amir; Lin, Heather; Abdelrahim, Maen; Rondon, Gabriela; Andersson, Borje S; Afrough, Aimaz; Martinez, Charles S; Tarrand, Jeffrey J; Kontoyiannis, Dimitrios P.; Marin, David; Gaber, A. Osama; Salahudeen, Abdulla; Oran, Betul; Chemaly, Roy F.; Olson, Amanda; Jones, Roy; Popat, Uday; Champlin, Richard E; Shpall, Elizabeth J.; Winkelmayer, Wolfgang C.; Rezvani, Katayoun

2017-01-01

Nephropathy due to BK virus infection is an evolving challenge in patients undergoing hematopoietic stem cell transplantation. We hypothesized that BKV infection was a marker of Kidney Function Decline and a poor prognostic factor in HSCT recipients who experience this complication. In this retrospective study, we analyzed all patients who underwent their first allogeneic hematopoietic stem cell transplantation at our institution between 2004 and 2012. We evaluated the incidence of persistent kidney function decline, which was defined as a confirmed reduction in estimated glomerular filtration rate of at least 25% from baseline using the CKD-EPI equation. Cox proportional hazard regression was used to model the cause-specific hazard of kidney function decline and Fine and Gray’s method was used to account for the competing risks of death. Among 2477 recipients of a first allogeneic hematopoietic stem cell transplantation, BK viruria was detected in 25% (n=629) and kidney function decline in 944 (38.1%). On multivariate analysis, after adjusting for age, sex, acute graft-versus-host disease, chronic graft versus host disease, preparative conditioning regimen, and graft source, BK viruria remained a significant risk factor for kidney function decline (P <0.001). In addition, patients with BKV infection and kidney function decline experienced worse overall survival. Post-allogeneic hematopoietic stem cell transplantation, BKV infection was strongly and independently associated with subsequent kidney function decline and worse patient survival after HSCT. PMID:26608093

Dynamics of Db isotopes formed in reactions induced by 238U, 248Cm, and 249Bk across the Coulomb barrier

NASA Astrophysics Data System (ADS)

Kaur, Gurjit; Sandhu, Kirandeep; Kaur, Amandeep; Sharma, Manoj K.

2018-05-01

The dynamical cluster decay model is employed to investigate the decay of *265Db and *267Db nuclei, formed in the 27Al+238U , 18O+249Bk , and 19F+248Cm hot fusion reactions at energies around the Coulomb barrier. First, the fission dynamics of the 27Al+238U reaction is explored by investigating the fragmentation and preformation yield of the reaction. The symmetric mass distribution of the fission fragments is observed for *265Db nucleus, when static β2 i deformations are used within hot optimum orientation approach. However, the mass split gets broaden for the use of β2 i-dynamical hot configuration of the fragments and becomes clearly asymmetric for the cold-static-deformed approach. Within the application of cold orientations of fragments, a new fission channel is observed at mass asymmetry η =0.29 . In addition to 238U-induced reaction, the work is carried out to address the fission and neutron evaporation cross sections of *267Db nucleus formed via 19F+248Cm and 18O+249Bk reactions, besides a comprehensive analysis of fusion and capture processes. Higher fusion cross sections and compound nucleus formation probabilities (PCN) are obtained for the 18O+249Bk reaction, as larger mass asymmetry in the entrance channel leads to reduced Coulomb factor. Finally, the role of sticking (IS) and nonsticking (INS) moments of inertia is analyzed for the 4 n and 5 n channels of *267Db nuclear system.

A combination of genistein and magnesium enhances the vasodilatory effect via an eNOS pathway and BK(Ca) current amplification.

PubMed

Sun, Lina; Hou, Yunlong; Zhao, Tingting; Zhou, Shanshan; Wang, Xiaoran; Zhang, Liming; Yu, Guichun

2015-04-01

The phytoestrogen genistein (GST) and magnesium have been independently shown to regulate vascular tone; however, their individual vasodilatory effects are limited. The aim of this study was to examine the combined effects of GST plus magnesium on vascular tone in mesenteric arteries. The effects of pretreatment with GST (0-200 μmol/L), MgCl2 (0-4.8 mmol/L) and GST plus MgCl2 on 10 μmol/L phenylephrine (PE) precontracted mesenteric arteries in rats were assessed by measuring isometric force. BK(Ca) currents were detected by the patch clamp method. GST caused concentration- and partial endothelium-dependent relaxation. Magnesium resulted in dual adjustment of vascular tone. Magnesium-free solution eliminated the vasodilatation of GST in both endothelium-intact and denuded rings. GST (50 μmol/L) plus magnesium (4.8 mmol/L) caused stronger relaxation in both endothelium-intact and denuded rings. Pretreatment with the nitric oxide synthase (NOS) inhibitor L-N-nitroarginine methyl ester (L-NAME, 100 μmol/L) significantly inhibited the effects of GST, high magnesium, and the combination of GST and magnesium. BK(Ca) currents were amplified to a greater extent when GST (50 μmol/L) was combined with 4.8 versus 1.2 mmol/L Mg(2+). Our data suggest that GST plus magnesium provides enhanced vasodilatory effects in rat mesenteric arteries compared with that observed when either is used separately, which was related to an eNOS pathway and BK(Ca) current amplification.

Cryogenic Temperature-dependent Refractive Index Measurements of N-BK7, BaLKN3, and SF15 for NOTES PDI

NASA Technical Reports Server (NTRS)

Frey, Bradley J.; Leviton, Douglas F.; Madison, Timothy J.

2007-01-01

In order to enable high quality lens designs using N-BK7, BaLKN3, and SF15 at cryogenic temperatures, we have measured the absolute refractive index of prisms of these three materials using the Cryogenic, High-Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center, as a function of both wavelength and temperature. For N-BK7, we report absolute refractive index and thermo-optic coefficient (dn/dT) at temperatures ranging from 50 to 300 K at wavelengths from 0.45 to 2.7 micrometers; for BaLKN3 we cover temperatures ranging from 40 to 300 K and wavelengths from 0.4 to 2.6 micrometers; for SF15 we cover temperatures ranging from 50 to 300 K and wavelengths from 0.45 to 2.6 micrometers. We compare our measurements with others in the literature and provide temperature-dependent Sellmeier coefficients based on our data to allow accurate interpolation of index to other wavelengths and temperatures. While we generally find good agreement (plus or minus 2 x 10(exp -4) for N-BK7, less than 1 x 10(exp -4) for the other materials) at room temperature between our measured values and those provided by the vendor, there is some variation between the datasheets provided with the prisms we measured and the catalog values published by the vendor. This underlines the importance of measuring the absolute refractive index of the material when precise knowledge of the refractive index is required.

Comparative evaluation of laboratory developed real-time PCR assays and RealStar(®) BKV PCR Kit for quantitative detection of BK polyomavirus.

PubMed

Hasan, Mohammad R; Tan, Rusung; Al-Rawahi, Ghada; Thomas, Eva; Tilley, Peter

2016-08-01

Quantitative, viral load monitoring for BK virus (BKV) by real-time PCR is an important tool in the management of polyomavirus associated nephropathy in renal transplant patients. However, variability in PCR results has been reported because of polymorphisms in viral genes among different subtypes of BKV, and lack of standardization of the PCR assays among different laboratories. In this study we have compared the performance of several laboratory developed PCR assays that target highly conserved regions of BKV genome with a commercially available, RealStar(®) BKV PCR Kit. Three real-time PCR assays (i) VP1 assay: selected from the literature that targets the major capsid protein (VP1) gene (ii) VP1MOD assay: VP1 assay with a modified probe, and (iii) BKLTA assay: newly designed assay that targets the large T antigen gene were assessed in parallel, using controls and clinical specimens that were previously tested using RealStar(®) BKV PCR Kit (Altona Diagnostics GmbH, Hamburg, Germany). Nucleic acid from all samples were extracted using the QIA symphony virus/bacteria kit on an automated DNA extraction platform QIA symphony SP (Qiagen). Primer and probe concentration, and reaction conditions for laboratory developed assays were optimized and the limit of detection of different assays was determined. Positive control for laboratory developed BK assays was prepared through construction of a plasmid carrying respective amplicon sequences. The 95% detection limit of VP1, VP1MOD and BKLTA assays were 1.8×10(2), 3×10(3) and 3.5×10(2) genomic copies/ml, respectively, as determined by Probit regression analysis of data obtained by testing a dilution series of a titered patient specimen, using RealStar(®) BKV PCR Kit. The inter-assay and intra-assay, coefficient of variations of these assays using calibrated, plasmid standards were <1%. All assays, including the RealStar(®) BKV PCR assay, were highly specific when tested against a panel of external proficiency

BK Polyomavirus: Clinical Aspects, Immune Regulation, and Emerging Therapies.

PubMed

Ambalathingal, George R; Francis, Ross S; Smyth, Mark J; Smith, Corey; Khanna, Rajiv

2017-04-01

BK polyomavirus (BKV) causes frequent infections during childhood and establishes persistent infections within renal tubular cells and the uroepithelium, with minimal clinical implications. However, reactivation of BKV in immunocompromised individuals following renal or hematopoietic stem cell transplantation may cause serious complications, including BKV-associated nephropathy (BKVAN), ureteric stenosis, or hemorrhagic cystitis. Implementation of more potent immunosuppression and increased posttransplant surveillance has resulted in a higher incidence of BKVAN. Antiviral immunity plays a crucial role in controlling BKV replication, and our increasing knowledge about host-virus interactions has led to the development of improved diagnostic tools and clinical management strategies. Currently, there are no effective antiviral agents for BKV infection, and the mainstay of managing reactivation is reduction of immunosuppression. Development of immune-based therapies to combat BKV may provide new and exciting opportunities for the successful treatment of BKV-associated complications. Copyright © 2017 American Society for Microbiology.

BK Polyomavirus: Clinical Aspects, Immune Regulation, and Emerging Therapies

PubMed Central

Ambalathingal, George R.; Francis, Ross S.; Smyth, Mark J.; Smith, Corey

2017-01-01

SUMMARY BK polyomavirus (BKV) causes frequent infections during childhood and establishes persistent infections within renal tubular cells and the uroepithelium, with minimal clinical implications. However, reactivation of BKV in immunocompromised individuals following renal or hematopoietic stem cell transplantation may cause serious complications, including BKV-associated nephropathy (BKVAN), ureteric stenosis, or hemorrhagic cystitis. Implementation of more potent immunosuppression and increased posttransplant surveillance has resulted in a higher incidence of BKVAN. Antiviral immunity plays a crucial role in controlling BKV replication, and our increasing knowledge about host-virus interactions has led to the development of improved diagnostic tools and clinical management strategies. Currently, there are no effective antiviral agents for BKV infection, and the mainstay of managing reactivation is reduction of immunosuppression. Development of immune-based therapies to combat BKV may provide new and exciting opportunities for the successful treatment of BKV-associated complications. PMID:28298471

BK virus encephalitis with thrombotic microangiopathy in an allogeneic hematopoietic stem cell transplant recipient.

PubMed

Lopes da Silva, R; Ferreira, I; Teixeira, G; Cordeiro, D; Mafra, M; Costa, I; Bravo Marques, J M; Abecasis, M

2011-04-01

BK virus (BKV) infection occurs most often in immunocompromised hosts, in the setting of renal or bone marrow transplantation. Hemorrhagic cystitis is the commonest manifestation but in recent years infections in other organ systems have been reported. We report an unusual case of biopsy-proven BKV encephalitis in a hematopoietic stem cell transplant patient who subsequently developed thrombotic microangiopathy. As far as we know, this is the first report of such an association in a transplant patient. © 2010 John Wiley & Sons A/S.

Quantification of BK polyoma viruria in Japanese children and adults with hemorrhagic cystitis complicating stem cell transplantation.

PubMed

Tanaka, Kaori; Hori, Tsukasa; Hatakeyama, Naoki; Yamamoto, Masaki; Takayama, Rumiko; Yoto, Yuko; Suzuki, Nobuhiro; Hayashi, Toshiaki; Ikeda, Yukiho; Ikeda, Hiroshi; Ishida, Tadao; Tsutsumi, Hiroyuki

2008-12-01

Polyoma BK virus (BKV) is frequently found in the urine of stem cell transplantation (SCT) patients with hemorrhagic cystitis (HC), but also occurs in SCT patients without HC. How BK viruria relates to the development of HC in SCT patients, especially in children, has not yet been fully evaluated. In the present study, we analyzed the relationship of several factors including urinary BKV load to HC development in children and adults undergoing SCT. We employed a quantitative PCR assay and evaluated 37 patients (aged 9 months-62 years) of whom 12 developed HC and 25 did not. Older age was a risk factor for the development of HC; however, other factors such as sex, primary disease, type of SCT, conditioning regimen and aGVHD were not. Peak urinary BKV values in HC patients were not higher than those in non-HC patients. Severity of HC also did not correlate with urinary BKV loads. However, in some patients who secreted higher urinary BKV loads, the peak loads were closely related with the onset of HC. Higher BKV loads may be a risk factor for the development of HC in conjunction with other coexisting factors.

BK Virus-Associated Hemorrhagic Cystitis After Allogeneic Hematopoietic Stem Cell Transplantation in the Pediatric Population.

PubMed

Pérez-Huertas, Pablo; Cueto-Sola, Margarita; Escobar-Cava, Paloma; Fernández-Navarro, José María; Borrell-García, Carmela; Albert-Marí, Asunción; López-Briz, Eduardo; Poveda-Andrés, José Luis

2016-02-22

To study the incidence, risk factors, and treatment of hemorrhagic cystitis secondary to BK-virus reactivation (HC-BKV) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in the pediatric population. Case-control study in which all pediatric patients (0-18 years) who underwent allo-HSCT from September 2009 to January 2014 were followed. Twenty-nine patients underwent an allo-HSCT. The median age was 9 years (range = 6 months to 15 years), 61% male. The primary diagnosis was acute lymphoblastic leukemia (72.4%). Six (20.7%) developed HC-BKV. In a multivariate analysis of risk factors, it was observed that the reactivation of BK virus was associated with age more than 10 years (P = .098) and those with positive serology for Epstein-Barr virus (P = .06). Five of the 6 patients with HC-BKV received cidofovir (CDV) at doses of 3 to 5 mg/kg/week. The treatment lasted a median of 3 cycles (range = 2-5). One of the patients (20%) developed nephrotoxicity. Of the 5 patients treated with CDV, 3 (60%) had a complete response, 1 (20%) partial response, and 1 (20%) no response. We conclude that HC-BKV is a frequent complication after allo-HSCT. CDV therapy can be effective but controlled clinical trials are needed. © 2016 by Association of Pediatric Hematology/Oncology Nurses.

BK virus-associated renal problems--clinical implications.

PubMed

Pahari, Amitava; Rees, Lesley

2003-08-01

BK virus (BKV), a human polyomavirus, infects most of the human population, but clinically relevant infections are usually limited to individuals who are immunosuppressed. After primary infection, BKV remains latent in the kidneys and can be reactivated in immune deficiency conditions, including transplantation. As primary infection occurs in childhood, BKV may be particularly important in the pediatric transplant population. BKV is associated with tubulointerstitial nephritis and ureteric stenosis in renal transplant recipients and hemorrhagic cystitis in bone marrow transplant recipients. There are increasing reports of BKV causing nephropathy and cystitis in non-renal solid organ transplant recipients and other immunodeficiency diseases. This might be related to the use of more potent immunosuppressive regimens or increasing awareness of BKV as an important pathogen. Diagnosis of BKV disease is by biopsy. Histopathological changes in renal biopsy specimens may mimic rejection or drug toxicity, but BKV nuclear inclusions can be seen. Treatment is by reduction of immunosuppression. Antiviral agents such as cidofovir are showing promise. BKV DNA polymerase chain reaction in blood or biopsy may be helpful in monitoring therapy. The impact of BKV disease in children is not well understood and prospective studies are needed to elucidate this further. This article reviews the current understanding of BKV-associated renal problems.

Location of the β4 transmembrane helices in the BK potassium channel

PubMed Central

Wu, Roland S.; Chudasama, Neelesh; Zakharov, Sergey I.; Doshi, Darshan; Motoike, Howard; Liu, Guoxia; Yao, Yongneng; Niu, Xiaowei; Deng, Shi-Xian; Landry, Donald W.; Karlin, Arthur; Marx, Steven O.

2009-01-01

Large-conductance, voltage- and Ca2+-gated potassium (BK) channels control excitability in a number of cell types. BK channels are composed of α subunits, which contain the voltage-sensor domains and the Ca2+- sensor domains, and form the pore, and often one of four types of β subunits, which modulate the channel in a cell-specific manner. β4 is expressed in neurons throughout the brain. Deletion of β4 in mice causes temporal lobe epilepsy. Compared to channels composed of α alone, channels composed of α and β4 activate and deactivate more slowly. We inferred the locations of the two β4 transmembrane (TM) helices, TM1 and TM2, relative to the seven αTM helices, S0-S6, from the extent of disulfide bond formation between cysteines substituted in the extracellular flanks of these TM helices. We found that β4 TM2 is close to α S0 and that β4 TM1 is close to both α S1 and S2. At least at their extracellular ends, TM1 and TM2 are not close to S3 through S6. In six of eight of the most highly crosslinked cysteine pairs, four crosslinks from TM2 to S0 and one each from TM1 to S1 and S2 had small effects on the V50 and on the rates of activation and deactivation. That disulfide crosslinking caused only small functional perturbations is consistent with the proximity of the extracellular ends of TM2 to S0 and of TM1 to S1 and to S2, in both the open and closed states. PMID:19571123

Rheological properties of magnetorheological fluid and its finishing application on large aperture BK7 glass

NASA Astrophysics Data System (ADS)

Wang, C.; Wei, Q. L.; Huang, W.; Luo, Q.; He, J. G.; Tang, G. P.

2013-07-01

The CeO2 nanoparticles with modified surface and mean sizes distribution during 107.0 nm - 127.7 nm are used as abrasive in magnetorheological finishing (MRF) fluid. The slow rotation dispersion without shearing thinning is better than fast emulsification dispersion. Steady D-shaped finishing spots and high quality precise processing surface with PV=0.1λ, GRMS=0.002λ/cm, Rq=0.83 nm are obtained on a 435 mm x 435 mm BK7 glass under self-developed MRF apparatus.

Enhancement of blood-tumor barrier permeability by Sar-[D-Phe8]des-Arg9BK, a metabolically resistant bradykinin B1 agonist, in a rat C6 glioma model

PubMed Central

Cardoso, Ronie Cleverson; Lobão-Soares, Bruno; Bianchin, Marino Muxfeldt; Carlotti, Carlos Gilberto; Walz, Roger; Alvarez-Silva, Márcio; Trentin, Andréa Gonçalves; Nicolau, Mauro

2004-01-01

Background While it is well known that bradykinin B2 agonists increase plasma protein extravasation (PPE) in brain tumors, the bradykinin B1 agonists tested thus far are unable to produce this effect. Here we examine the effect of the selective B1 agonist bradykinin (BK) Sar-[D-Phe8]des-Arg9BK (SAR), a compound resistant to enzymatic degradation with prolonged activity on PPE in the blood circulation in the C6 rat glioma model. Results SAR administration significantly enhanced PPE in C6 rat brain glioma compared to saline or BK (p < 0.01). Pre-administration of the bradykinin B1 antagonist [Leu8]-des-Arg (100 nmol/Kg) blocked the SAR-induced PPE in the tumor area. Conclusions Our data suggest that the B1 receptor modulates PPE in the blood tumor barrier of C6 glioma. A possible role for the use of SAR in the chemotherapy of gliomas deserves further study. PMID:15458573

Polyomavirus BK: possibly associated skin eruption in a patient with hemorrhagic cystitis.

PubMed

Medeiros, Patricia V; Abagge, Kerstin T; Carvalho, Vânia O; Bonfim, Carmem M; Raboni, Sonia M

2011-01-01

A 14-year-old girl with Fanconi anemia was submitted to allogeneic hematopoietic stem cell transplantation. After 17 days she developed hemorrhagic cystitis due to polyoma BK virus (BKV), confirmed by PCR (polymerase chain reaction). Two weeks after the appearance of the urinary symptoms the patient presented numerous papules and vesicles on both hands and feet. PCR of the skin lesions and plasma was positive for BKV. The relationship of BKV with frequent infections in immunocompromised patients is well established. The positive PCR of vesicular fluid suggests that this was the causative agent of the skin lesion in this case. There are no reports of skin lesions with positive PCR for BKV. © 2011 Wiley Periodicals, Inc.

Functional coupling of TRPV4 channels and BK channels in regulating spontaneous contractions of the guinea pig urinary bladder.

PubMed

Isogai, Ayu; Lee, Ken; Mitsui, Retsu; Hashitani, Hikaru

2016-09-01

We investigated the role of TRPV4 channels (TRPV4) in regulating the contractility of detrusor smooth muscle (DSM) and muscularis mucosae (MM) of the urinary bladder. Distribution of TRPV4 in DSM and MM of guinea-pig bladders was examined by fluorescence immunohistochemistry. Changes in the contractility of DSM and MM bundles were measured using isometric tension recording. Intracellular Ca(2+) dynamics were visualized by Cal-520 fluorescent Ca(2+) imaging, while membrane potential changes were recorded using intracellular microelectrode technique. DSM and MM expressed TRPV4 immunoreactivity. GSK1016790A (GSK, 1 nM), a TRPV4 agonist, evoked a sustained contraction in both DSM and MM associated with a cessation of spontaneous phasic contractions in a manner sensitive to HC-067047 (10 μM), a TRPV4 antagonist. Iberiotoxin (100 nM) and paxilline (1 μM), large conductance Ca(2+)-activated K(+) (BK) channel blockers restored the spontaneous contractions in GSK. The sustained contractions in DSM and MM were reduced by nifedipine (10 μM), a blocker of L-type voltage-dependent Ca(2+) channels (LVDCCs) by about 40 % and by nominally Ca(2+)-free solution by some 90 %. GSK (1 nM) abolished spontaneous Ca(2+) transients, increased basal Ca(2+) levels and also prevented spontaneous action potential discharge associated with DSM membrane hyperpolarization. In conclusion, Ca(2+) influx through TRPV4 appears to activate BK channels to suppress spontaneous contractions and thus a functional coupling of TRPV4 with BK channels may act as a self-limiting mechanism for bladder contractility during its storage phase. Despite the membrane hyperpolarization in GSK, Ca(2+) entry mainly through TRPV4 develops the tonic contraction.

Unusual presentations of BK virus infections in pediatric renal transplant recipients.

PubMed

Drake, Keri A; Najera, Lydia; Reed, Robyn C; Verghese, Priya S

2013-02-01

BKV has emerged as a significant pathogen in the field of transplantation, predominantly causing BKV nephropathy in renal transplant recipients and hemorrhagic cystitis in HSCT recipients. However, case reports describe more diverse complications, and we too present three unusual cases of BKV infections in pediatric renal transplant recipients. First, we describe a case of biopsy-proven renal damage secondary to BKV prior to the onset of viremia, demonstrating that BKV nephropathy can occur without preceding viremia. We also present two renal transplant recipients with persistent BK viruria, one with BKV-associated hemorrhagic cystitis and the other with microscopic hematuria. Therefore, we conclude that BKV manifestations may be more diverse than previously thought and suggest clinical utility in urine BKV qPCR testing in specific transplant recipients. © 2012 John Wiley & Sons A/S.

Fatal BK virus pneumonia following stem cell transplantation.

PubMed

Akazawa, Y; Terada, Y; Yamane, T; Tanaka, S; Aimoto, M; Koh, H; Nakane, T; Koh, K-R; Nakamae, H; Ohsawa, M; Wakasa, K; Hino, M

2012-12-01

We report the case of a 39-year-old male patient who died of severe BK virus (BKV) pneumonia 168 days after hematopoietic stem cell transplantation (HSCT) for acute lymphoblastic leukemia. After suffering from BKV-associated late-onset hemorrhagic cystitis (HC) with long-term sustained BKV viremia, he died of rapidly progressive pneumonia. On autopsy, numerous viral intranuclear inclusions were seen in his lungs and bladder. An immunohistochemical examination of his lungs was positive for simian virus 40. Based on these pathological results and the high sustained BKV viral load in his blood, we reached a diagnosis of BKV pneumonia. Viral infection can occasionally become life threatening among HSCT recipients. It is widely known that BKV can cause late-onset HC, but BKV-associated pneumonia is rare. Because of its rapid progression and poor prognosis, it is difficult to make an antemortem diagnosis of BKV pneumonia. A treatment strategy for BKV pneumonia also needs to be formulated. Similar to other viral pathogens, BKV can cause pneumonia and the clinician should therefore be aware of it in immunocompromised patients. © 2012 John Wiley & Sons A/S.

BK polyomavirus genotypes Ia and Ib1 exhibit different biological properties in renal transplant recipients.

PubMed

Varella, Rafael B; Zalona, Ana Carolina J; Diaz, Nuria C; Zalis, Mariano G; Santoro-Lopes, Guilherme

2018-01-02

BK polyomavirus (BKV) is an opportunist agent associated with nephropathy (BKVAN) in 1-10% of kidney transplant recipients. BKV is classified into genotypes or subgroups according to minor nucleotidic variations with unknown biological implications. Studies assessing the possible association between genotypes and the risk of BKVAN in kidney transplant patients have presented conflicting results. In these studies, genotype Ia, which is highly prevalent in Brazil, was less frequently found and, thus, comparative data on the biological properties of this genotype are lacking. In this study, BKV Ia and Ib1 genotypes were compared according to their viral load, genetic evolution (VP1 and NCCR) - in a cohort of renal transplant recipients. The patients infected with Ia (13/23; 56.5%) genotype exhibited higher viral loads in urine [>1.4 log over Ib1 (10/23; 43.5%); p=0.025]. In addition, genotype Ia was associated with diverse mutations at VP1 loops and sites under positive selection outside loops, which were totally absent in Ib1. Although the number of viremic patients was similar, the three patients who had BK nephropathy (BKVAN) were infected with Ia genotype. NCCR architecture (ww or rr) were not distinctive between Ia and Ib1 genotypes. Ia genotype, which is rare in other published BKV cohorts, presented some diverse biological properties in transplanted recipients in comparison to Ib1. Copyright © 2017 Elsevier B.V. All rights reserved.

Diffuse gastrointestinal bleeding and BK polyomavirus replication in a pediatric allogeneic haematopoietic stem cell transplant patient.

PubMed

Koskenvuo, M; Lautenschlager, I; Kardas, P; Auvinen, E; Mannonen, L; Huttunen, P; Taskinen, M; Vettenranta, K; Hirsch, H H

2015-01-01

Patients undergoing haematopoietic stem cell transplantation (HSCT) are at high risk of severe gastrointestinal bleeding caused by infections, graft versus host disease, and disturbances in haemostasis. BK polyomavirus (BKPyV) is known to cause hemorrhagic cystitis, but there is also evidence of BKV shedding in stool and its association with gastrointestinal disease. We report putative association of BKPyV replication with high plasma viral loads in a pediatric HSCT patient developing hemorrhagic cystitis and severe gastrointestinal bleeding necessitating intensive care. The observation was based on chart review and analysis of BKPyV DNA loads in plasma and urine as well as retrospective BKPyV-specific IgM and IgG measurements in weekly samples until three months post-transplant. The gastrointestinal bleeding was observed after a >100-fold increase in the plasma BKPyV loads and the start of hemorrhagic cystitis. The BKPyV-specific antibody response indicated past infection prior to transplantation, but increasing IgG titers were seen following BKPyV replication. The gastrointestinal biopsies were taken at a late stage of the episode and were no longer informative of BK polyomavirus involvement. In conclusion, gastrointestinal complications with bleeding are a significant problem after allogeneic HSCT to which viral infections including BKPyV may contribute. Copyright © 2014 Elsevier B.V. All rights reserved.

The polyomavirus BK agnoprotein co-localizes with lipid droplets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Unterstab, Gunhild; Gosert, Rainer; Leuenberger, David

Agnoprotein encoded by human polyomavirus BK (BKV) is a late cytoplasmic protein of 66 amino acids (aa) of unknown function. Immunofluorescence microscopy revealed a fine granular and a vesicular distribution in donut-like structures. Using BKV(Dunlop)-infected or agnoprotein-transfected cells, we investigated agnoprotein co-localization with subcellular structures. We found that agnoprotein co-localizes with lipid droplets (LD) in primary human renal tubular epithelial cells as well as in other cells supporting BKV replication in vitro (UTA, Vero cells). Using agnoprotein-enhanced green fluorescent protein (EGFP) fusion constructs, we demonstrate that agnoprotein aa 20-42 are required for targeting LD, whereas aa 1-20 or aa 42-66more » were not. Agnoprotein aa 22-40 are predicted to form an amphipathic helix, and mutations A25D and F39E, disrupting its hydrophobic domain, prevented LD targeting. However, changing the phosphorylation site serine-11 to alanine or aspartic acid did not alter LD co-localization. Our findings provide new clues to unravel agnoprotein function.« less

Low resistance, large dimension entrance to the inner cavity of BK channels determined by changing side-chain volume

PubMed Central

Niu, Xiaowei

2011-01-01

Large-conductance Ca2+- and voltage-activated K+ (BK) channels have the largest conductance (250–300 pS) of all K+-selective channels. Yet, the contributions of the various parts of the ion conduction pathway to the conductance are not known. Here, we examine the contribution of the entrance to the inner cavity to the large conductance. Residues at E321/E324 on each of the four α subunits encircle the entrance to the inner cavity. To determine if 321/324 is accessible from the inner conduction pathway, we measured single-channel current amplitudes before and after exposure and wash of thiol reagents to the intracellular side of E321C and E324C channels. MPA− increased currents and MTSET+ decreased currents, with no difference between positions 321 and 324, indicating that side chains at 321/324 are accessible from the inner conduction pathway and have equivalent effects on conductance. For neutral amino acids, decreasing the size of the entrance to the inner cavity by substituting large side-chain amino acids at 321/324 decreased outward single-channel conductance, whereas increasing the size of the entrance with smaller side-chain substitutions had little effect. Reductions in outward conductance were negated by high [K+]i. Substitutions had little effect on inward conductance. Fitting plots of conductance versus side-chain volume with a model consisting of one variable and one fixed resistor in series indicated an effective diameter and length of the entrance to the inner cavity for wild-type channels of 17.7 and 5.6 Å, respectively, with the resistance of the entrance ∼7% of the total resistance of the conduction pathway. The estimated dimensions are consistent with the structure of MthK, an archaeal homologue to BK channels. Our observations suggest that BK channels have a low resistance, large entrance to the inner cavity, with the entrance being as large as necessary to not limit current, but not much larger. PMID:21576375

Effects of in ovo exposure to benzo[k]fluoranthene (BkF) on CYP1A expression and promoter methylation in developing chicken embryos.

PubMed

Brandenburg, Jonas; Head, Jessica A

2018-01-01

Polycyclic aromatic hydrocarbons (PAHs) are toxic environmental pollutants that are potent teratogens. Recent research suggests that early life exposure to PAHs can affect health outcomes later in life. Some of these latent responses may be mediated by epigenetic mechanisms such as DNA methylation. The role of DNA methylation in regulating responses to PAHs in birds is currently unknown. Here, we assess the effect of in ovo exposure to the model PAH, benzo[k]fluoranthene (BkF), on aryl hydrocarbon receptor (AHR) mediated cytochrome P4501A (CYP1A) gene expression and promoter methylation in chicken embryos. Fertilized chicken eggs were injected with BkF (0-100μg/kg) prior to incubation. BkF exposure was associated with an increase in CYP1A4 and CYP1A5 mRNA levels at mid-incubation (embryonic day 10), which dropped to baseline levels towards the end of the incubation period (embryonic day 19). The transient induction in CYP1A expression was accompanied by small but significant increases in CYP1A promoter methylation, which persisted until after shortly after hatching. Methylation within the CYP1A promoter was correlated with levels of CYP1A5, but not CYP1A4 mRNA. Characterization of the role of DNA methylation in the AHR response pathway may increase our understanding of the effects of early life exposure to PAHs in birds. Copyright © 2017 Elsevier Inc. All rights reserved.

Atomic determinants of BK channel activation by polyunsaturated fatty acids

PubMed Central

Tian, Yutao; Aursnes, Marius; Hansen, Trond Vidar; Tungen, Jørn Eivind; Galpin, Jason D.; Leisle, Lilia; Ahern, Christopher A.; Xu, Rong; Heinemann, Stefan H.; Hoshi, Toshinori

2016-01-01

Docosahexaenoic acid (DHA), a polyunsaturated ω-3 fatty acid enriched in oily fish, contributes to better health by affecting multiple targets. Large-conductance Ca2+- and voltage-gated Slo1 BK channels are directly activated by nanomolar levels of DHA. We investigated DHA–channel interaction by manipulating both the fatty acid structure and the channel composition through the site-directed incorporation of unnatural amino acids. Electrophysiological measurements show that the para-group of a Tyr residue near the ion conduction pathway has a critical role. To robustly activate the channel, ionization must occur readily by a fatty acid for a good efficacy, and a long nonpolar acyl tail with a Z double bond present at the halfway position for a high affinity. The results suggest that DHA and the channel form an ion–dipole bond to promote opening and demonstrate the channel druggability. DHA, a marine-derived nutraceutical, represents a promising lead compound for rational drug design and discovery. PMID:27849612

Astaxanthin and Docosahexaenoic Acid Reverse the Toxicity of the Maxi-K (BK) Channel Antagonist Mycotoxin Penitrem A

PubMed Central

Goda, Amira A.; Naguib, Khayria M.; Mohamed, Magdy M.; Amra, Hassan A.; Nada, Somaia A.; Abdel-Ghaffar, Abdel-Rahman B.; Gissendanner, Chris R.; El Sayed, Khalid A.

2016-01-01

Penitrem A (PA) is a food mycotoxin produced by several terrestrial and few marine Penicillium species. PA is a potent tremorgen through selective antagonism of the calcium-dependent potassium BK (Maxi-K) channels. Discovery of natural products that can prevent the toxic effects of PA is important for food safety. Astaxanthin (AST) is a marine natural xanthophyll carotenoid with documented antioxidant activity. Unlike other common antioxidants, AST can cross blood brain barriers (BBBs), inducing neuroprotective effects. Docosahexaenoic acid (DHA) is polyunsaturated ω-3 fatty acid naturally occurring in fish and algae. DHA is essential for normal neurological and cellular development. This study evaluated the protective activity of AST and DHA against PA-induced toxicity, in vitro on Schwann cells CRL-2765 and in vivo in the worm Caenorhbitidis elegans and Sprague Dawley rat models. PA inhibited the viability of Schwann cells, with an IC50 of 22.6 μM. Dose-dependent treatments with 10–100 μM DHA significantly reversed the PA toxicity at its IC50 dose, and improved the survival of Schwann cells to 70.5%–98.8%. Similarly, dose-dependent treatments with 10–20 μM AST reversed the PA toxicity at its IC50 dose and raised these cells’ survival to 61.7%–70.5%. BK channel inhibition in the nematode C. elegans is associated with abnormal reversal locomotion. DHA and AST counteracted the in vivo PA BK channel antagonistic activity in the C. elegans model. Rats fed a PA-contaminated diet showed high levels of glutamate (GLU), aspartate (ASP), and gamma amino butyric acid (GABA), with observed necrosis or absence of Purkinjie neurons, typical of PA-induced neurotoxicity. Dopamine (DA), serotonin (5-HT), and norepinephrine (NE) levels were abnormal, Nitric Oxide (NO) and Malondialdehyde (MDA) levels were significantly increased, and total antioxidant capacity (TAC) level in serum and brain homogenates was significantly decreased in PA-treated rats. DHA and AST

BK polyomavirus encephalitis in a patient with thrombotic microangiopathy after an allogeneic hematopoietic stem cell transplant.

PubMed

Jun, Jae-Bum; Choi, Yunsuk; Kim, Hawk; Lee, Sun Ho; Jeong, Joseph; Jung, Jiwon

2016-12-01

To date, only one case of BK polyomavirus (BKPyV) encephalitis combined with transplant-associated thrombotic microangiopathy has been reported in an hematopoietic stem cell transplantation (HCT) recipient. We report the case of an HCT recipient who developed thrombotic microangiopathy and subsequent BKPyV encephalitis. She died despite treatment with cidofovir, ciprofloxacin, and intravenous immunoglobulin without improvement in mental status. Early suspicion of BKPyV encephalitis in an HCT recipient presenting with altered mental status and hemorrhagic cystitis is important. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The first transmembrane domain (TM1) of β2-subunit binds to the transmembrane domain S1 of α-subunit in BK potassium channels

PubMed Central

Morera, Francisco J.; Alioua, Abderrahmane; Kundu, Pallob; Salazar, Marcelo; Gonzalez, Carlos; Martinez, Agustin D.; Stefani, Enrico; Toro, Ligia; Latorre, Ramon

2012-01-01

The BK channel is one of the most broadly expressed ion channels in mammals. In many tissues, the BK channel pore-forming α-subunit is associated to an auxiliary β-subunit that modulates the voltage- and Ca2+-dependent activation of the channel. Structural components present in β-subunits that are important for the physical association with the α-subunit are yet unknown. Here, we show through co-immunoprecipitation that the intracellular C-terminus, the second transmembrane domain (TM2) and the extracellular loop of the β2-subunit are dispensable for association with the α-subunit pointing transmembrane domain 1 (TM1) as responsible for the interaction. Indeed, the TOXCAT assay for transmembrane protein–protein interactions demonstrated for the first time that TM1 of the β2-subunit physically binds to the transmembrane S1 domain of the α-subunit. PMID:22710124

Incidence and Factors Associated with De Novo DSA After BK Viremia in Renal Transplant Recipients.

PubMed

Patel, Samir J; Kuten, Samantha A; Knight, Richard J; Graviss, Edward A; Nguyen, Duc; Gaber, A Osama

2016-01-01

BK polyomavirus infection and de novo donor-human leukocyte antigen (HLA) specific antibodies (dnDSA) are two well-known and distinct complications occurring after kidney transplantation. Recent literature suggests an association between the two events. This study aims to examine the relationship between BK viremia (BKV) and dnDSA and to identify potential risk factors for dnDSA following BKV in kidney transplant recipients. A retrospective review of 1019 recipients from Houston Methodist Hospital was conducted. All patients underwent routine screening for BKV and dnDSA. Median follow-up was 44 months. BKV was detected in 186 (18%) patients at a median of 107 (82-205) days post-transplant. dnDSA occurred in 283 (28%) patients at a median of 272 (62-575) days post-transplant. Of the 69 dnDSA-positive/BKV-positive patients, dnDSA detection occurred after BKV onset in 46 patients. Thus, 46 (28%) previously DSA-negative patients later became dnDSA-positive following BKV, not significantly different from the rate seen in BKV-negative patients (26%; p=0.5). Median time to DSA detection following BKV onset was 232 days (interquartile range, 119-460) post-BKV detection. Multivariate analysis revealed a greater number of HLA mismatches and viral clearance as risk factors for development of dnDSA following BKV, whereas delayed graft function was associated with a lower risk of dnDSA. In conclusion, despite being considered a result of over-immunosuppression, BKV can still be followed by dnDSA in a substantial proportion of patients. Monitoring for dnDSA in patients being managed for BKV may be warranted. Copyright© 2017 by the Terasaki Research Institute.

Prevalence of BK virus subtype I in Germany.

PubMed

Krumbholz, Andi; Zell, Roland; Egerer, Renate; Sauerbrei, Andreas; Helming, Andrea; Gruhn, Bernd; Wutzler, Peter

2006-12-01

The primary infection with human polyomavirus BK (BKV) occurs in early childhood and leads to viral latency within the urogenital tract. Up to 90% of the adult population are seropositive. In immunosuppressed patients, the BKV may be reactivated resulting in typical disease patterns like hemorrhagic cystitis and tubulointerstitial nephritis. Based on serological and molecular methods, BKV isolates were classified into four subtypes previously. Sixty specimens obtained from German renal and bone marrow transplant recipients were analyzed to gain data on the prevalence of BKV subtypes in Germany. With 90.9%, BKV subtype I was found to be predominant in both patient groups. 6.1% of BKV strains were classified as subtype IV. This pattern of phylogenetic distribution is similar to that demonstrated previously in England, Tanzania, the United States and Japan. Remarkably, there was one German BKV virus with a sequence which clusters together with strain SB in subtype II. The BKV subtype I was found to consist of at least three subgroups designated as Ia, Ib, and Ic. While the majority of the German sequences represent subgroup Ic, most of the Japanese sequences are clearly distinct. These findings support the hypothesis of distinct geographical prevalence of BKV subgroups. For the genotyping region, a relationship of BKV subgroups to disease patterns like hemorrhagic cystitis or tubulointerstitial nephritis could not be demonstrated. (c) 2006 Wiley-Liss, Inc.

Kidney and bladder outcomes in children with hemorrhagic cystitis and BK virus infection after allogeneic hematopoietic stem cell transplantation

PubMed Central

Oshrine, Benjamin; Bunin, Nancy; Li, Yimei; Furth, Susan; Laskin, Benjamin L

2015-01-01

BK virus (BKV) infection is associated with hemorrhagic cystitis (HC) in hematopoietic stem cell transplant (HSCT) recipients and nephropathy after kidney transplant. We assessed the association between BKV and kidney and bladder complications in children developing HC by retrospectively reviewing 221 consecutive pediatric allogeneic HSCT recipients at the Children’s Hospital of Philadelphia from 2005–2011. We included all patients with BKV PCR testing performed for clinical indication from day 0 until 1 year post-HSCT (N=68). We assessed the association of any BKV infection (urine and/or blood) or peak BK viremia ≥10,000 copies/ml (high viremia) with severe HC (defined as grade IV—bladder catheterization or surgical intervention), the need for dialysis, serum creatinine-estimated glomerular filtration rate (eGFR) at the time of BKV testing, day 100, and day 365, and death. Children with high viremia more likely developed severe HC compared to those with peak viremia <10,000 copies/mL (21% versus 2%; p=0.02). BKV infection of the blood or urine was not associated with the need for dialysis, change in eGFR, or mortality. BKV infection is common after pediatric allogeneic HSCT and plasma testing in those with HC may predict patients who will develop severe bladder injury. PMID:24060406

The polyomavirus puzzle: is host immune response beneficial in controlling BK virus after adult hematopoietic cell transplantion?

PubMed Central

Satyanarayana, G.; Marty, F.M.; Tan, C.S.

2014-01-01

BK virus (BKV), an ubiquitous human polyomavirus, usually does not cause disease in healthy individuals. BKV reactivation and disease can occur in immunosuppressed individuals, such as those who have undergone renal transplantation or hematopoietic cell transplantation (HCT). Clinical manifestations of BKV disease include graft dysfunction and failure in renal transplant recipients; HCT recipients frequently experience hematuria, cystitis, hemorrhagic cystitis (HC), and renal dysfunction. Studies of HCT patients have identified several risk factors for the development of BKV disease including myeloablative conditioning, acute graft-versus-host disease, and undergoing an umbilical cord blood (uCB) HCT. Although these risk factors indicate that alterations in the immune system are necessary for BKV pathogenesis in HCT patients, few studies have examined the interactions between host immune responses and viral reactivation in BKV disease. Specifically, having BKV immunoglobulin-G before HCT does not protect against BKV infection and disease after HCT. A limited number of studies have demonstrated BKV- specific cytotoxic T-cells in healthy adults as well as in post-HCT patients who had experienced HC. New areas of research are required for a better understanding of this emerging infectious disease post HCT, including prospective studies examining BK viruria, viremia, and their relationship to clinical disease, a detailed analysis of urothelial histopathology, and laboratory evaluation of systemic and local cellular and humoral immune responses to BKV in patients receiving HCT from different sources, including uCB and haploidentical donors. PMID:24834968

A real time genotyping PCR assay for polyomavirus BK.

PubMed

Gard, Lilli; Niesters, Hubert G M; Riezebos-Brilman, Annelies

2015-09-01

Polyomavirus BK (BKV) may cause nephropathy in renal transplant recipients and hemorrhagic cystitis in bone marrow recipients. We developed real-time PCRs (RT-PCR) to determine easily and rapidly the different BKV genotypes (BKGT) (I-IV). On the VP1 gene a duplex of RT-PCRs was developed and validated to differentiate the four main BKGT. 212 BKV positive samples (21 plasma, 191 urine) were tested with these specific PCRs. Of these 212 samples, 55 PCR results were additionally confirmed by sequencing a VP1 gene fragment (nucleotide 1630-1956). For every genotype, a highly specific, precise and internally controlled assay was developed with a limit of detection of log 3 copies per ml. In 18 (8.5%) of these samples genotyping was not successful due to a low viral load. By sequence analysis, the genotype of 46 out of 55 and 2 out of 4 samples with double infection could be confirmed. This study describes RT-PCRs for detection of the main BKGT. It proved to be rapid, cheap and sensitive compared to sequencing. Double infections can also be detected. This method will be of value to investigate the role of BKV infection in relation to the genotype. Copyright © 2015 Elsevier B.V. All rights reserved.

Diagnostic value of JC/BK virus antibody immunohistochemistry staining in urine samples from posttransplant immunosuppressed patients in relation to polyomavirus reactivation.

PubMed

Yuste, Rosario Sanchez; Frías, Carolina; López, Ana; Vallejo, Carlos; Martín, Paloma; Bellas, Carmen

2008-01-01

To compare the diagnostic value of cytology and immunohistochemistry staining (IHS) of urine samples for polyomavirus reactivation diagnosis. Sixty-eight urine samples collected from 18 immunosuppressed patients were analyzed by Papanicolaou and IHS with a JC/BK virus-specific monoclonal antibody. Overall, polyomavirus BK (BKV) was positive in 11 of 18 patients (61.1%) (3 of whom developed hemorrhagic cystitis) and in 23 of 68 urine samples (28%). Of 23 samples, 4 (17%) were positive by 1 of the 2 techniques, only. Of 23 samples, 19 (83%) were positive by both methods. In matching urine samples from the same patient, the number of BKV-infected positive cells detected by IHS in urine slides was higher than those detected by Papanicolaou staining (71.3%). The main advantage of LHS is that it allowed confirmation of BKV infection diagnosis in urine samples. IHS detected more BKV-infected cells in samples with few positive urothelial cells, which would have gone undetected if only Papanicolaou staining had been used as the BKV screening method. Urine samples testing for BKV by both techniques will improve diagnosis in asymptomatic patients, allowing early therapeutic intervention and a better clinical outcome.

BK Virus and Its Role in Hematopoietic Stem Cell Transplantation: Evolution of a Pathogen.

PubMed

delaCruz, Jennifer; Pursell, Kenneth

2014-08-01

We reviewed the literature regarding disease induced by BK virus (BKV) in the hematopoietic stem cell transplant (HSCT) population, particularly hemorrhagic cystitis (HC) and nephritis. The association between BKV and HC has been reported over the past four decades. BKV has been clinically implicated and widely accepted as an etiologic agent of HC and nephritis in HSCT and nephropathy in renal transplant patients. We discuss the potential benefit of early initiation of therapy in patients who fail supportive care alone as well as the different treatment strategies for HC induced by BKV. Treatments that have been used such as cidofovir and leflunomide are accompanied by risks, and the benefits are not as concrete as with other viral illness in the HSCT population.

Investigating the dynamics of the surface roughness of BK7 and TF1 glasses when they are processed by surface lap

NASA Astrophysics Data System (ADS)

Obeid, A.

2005-12-01

The roughness dynamics of glasses of types BK7 (K8) and TF1 are investigated at the stage of grinding and polishing when they undergo free-lap processing. The relationship is established between the arithmetic-mean roughness and the abrasive graininess at the stage of grinding and the polishing time. It is shown that one can distinguish three stages in the formation of roughness during polishing.

Kidney and bladder outcomes in children with hemorrhagic cystitis and BK virus infection after allogeneic hematopoietic stem cell transplantation.

PubMed

Oshrine, Benjamin; Bunin, Nancy; Li, Yimei; Furth, Susan; Laskin, Benjamin L

2013-12-01

BK virus (BKV) infection is associated with hemorrhagic cystitis (HC) in hematopoietic stem cell transplantation (HSCT) recipients and nephropathy after kidney transplantation. We assessed the association between BKV and kidney and bladder complications in children developing HC by retrospectively reviewing 221 consecutive pediatric allogeneic HSCT recipients at the Children's Hospital of Philadelphia from 2005 to 2011. We included all patients with BKV PCR testing performed for clinical indication from day 0 until 1 year post-HSCT (N = 68). We assessed the association of any BKV infection (urine and/or blood) or peak BK viremia ≥ 10,000 copies/mL (high viremia) with severe HC (defined as grade IV-bladder catheterization or surgical intervention); the need for dialysis; serum creatinine-estimated glomerular filtration rate at the time of BKV testing, day 100, and day 365; and death. Children with high viremia more likely developed severe HC compared with those with peak viremia < 10,000 copies/mL (21% versus 2%; P = .02). BKV infection of the blood or urine was not associated with the need for dialysis, change in estimated glomerular filtration rate, or mortality. BKV infection is common after pediatric allogeneic HSCT, and plasma testing in those with HC may predict patients who will develop severe bladder injury. Copyright © 2013 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

The polyomavirus puzzle: is host immune response beneficial in controlling BK virus after adult hematopoietic cell transplantion?

PubMed

Satyanarayana, G; Marty, F M; Tan, C S

2014-08-01

BK virus (BKV), a ubiquitous human polyomavirus, usually does not cause disease in healthy individuals. BKV reactivation and disease can occur in immunosuppressed individuals, such as those who have undergone renal transplantation or hematopoietic cell transplantation (HCT). Clinical manifestations of BKV disease include graft dysfunction and failure in renal transplant recipients; HCT recipients frequently experience hematuria, cystitis, hemorrhagic cystitis (HC), and renal dysfunction. Studies of HCT patients have identified several risk factors for the development of BKV disease including myeloablative conditioning, acute graft-versus-host disease, and undergoing an umbilical cord blood (uCB) HCT. Although these risk factors indicate that alterations in the immune system are necessary for BKV pathogenesis in HCT patients, few studies have examined the interactions between host immune responses and viral reactivation in BKV disease. Specifically, having BKV immunoglobulin-G before HCT does not protect against BKV infection and disease after HCT. A limited number of studies have demonstrated BKV-specific cytotoxic T cells in healthy adults as well as in post-HCT patients who had experienced HC. New areas of research are required for a better understanding of this emerging infectious disease post HCT, including prospective studies examining BK viruria, viremia, and their relationship with clinical disease, a detailed analysis of urothelial histopathology, and laboratory evaluation of systemic and local cellular and humoral immune responses to BKV in patients receiving HCT from different sources, including uCB and haploidentical donors. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A fast BK-type KCa current acts as a postsynaptic modulator of temporal selectivity for communication signals.

PubMed

Kohashi, Tsunehiko; Carlson, Bruce A

2014-01-01

Temporal patterns of spiking often convey behaviorally relevant information. Various synaptic mechanisms and intrinsic membrane properties can influence neuronal selectivity to temporal patterns of input. However, little is known about how synaptic mechanisms and intrinsic properties together determine the temporal selectivity of neuronal output. We tackled this question by recording from midbrain electrosensory neurons in mormyrid fish, in which the processing of temporal intervals between communication signals can be studied in a reduced in vitro preparation. Mormyrids communicate by varying interpulse intervals (IPIs) between electric pulses. Within the midbrain posterior exterolateral nucleus (ELp), the temporal patterns of afferent spike trains are filtered to establish single-neuron IPI tuning. We performed whole-cell recording from ELp neurons in a whole-brain preparation and examined the relationship between intrinsic excitability and IPI tuning. We found that spike frequency adaptation of ELp neurons was highly variable. Postsynaptic potentials (PSPs) of strongly adapting (phasic) neurons were more sharply tuned to IPIs than weakly adapting (tonic) neurons. Further, the synaptic filtering of IPIs by tonic neurons was more faithfully converted into variation in spiking output, particularly at short IPIs. Pharmacological manipulation under current- and voltage-clamp revealed that tonic firing is mediated by a fast, large-conductance Ca(2+)-activated K(+) (KCa) current (BK) that speeds up action potential repolarization. These results suggest that BK currents can shape the temporal filtering of sensory inputs by modifying both synaptic responses and PSP-to-spike conversion. Slow SK-type KCa currents have previously been implicated in temporal processing. Thus, both fast and slow KCa currents can fine-tune temporal selectivity.

Calibration of BK Virus Nucleic Acid Amplification Testing to the 1st WHO International Standard for BK Virus

PubMed Central

Tan, Susanna K.; Milligan, Stephen; Sahoo, Malaya K.; Taylor, Nathaniel

2017-01-01

ABSTRACT Significant interassay variability in the quantification of BK virus (BKV) DNA precludes establishing broadly applicable thresholds for the management of BKV infection in transplantation. The 1st WHO International Standard for BKV (primary standard) was introduced in 2016 as a common calibrator for improving the harmonization of BKV nucleic acid amplification testing (NAAT) and enabling comparisons of biological measurements worldwide. Here, we evaluated the Altona RealStar BKV assay (Altona) and calibrated the results to the international unit (IU) using the Exact Diagnostics BKV verification panel, a secondary standard traceable to the primary standard. The primary and secondary standards on Altona had nearly identical linear regression equations (primary standard, Y = 1.05X − 0.28, R2 = 0.99; secondary standard, Y = 1.04X − 0.26, R2 = 0.99) and conversion factors (primary standard, 1.11 IU/copy; secondary standard, 1.09 IU/copy). A comparison of Altona with a laboratory-developed BKV NAAT assay in IU/ml versus copies/ml using Passing-Bablok regression revealed similar regression lines, no proportional bias, and improvement in the systematic bias (95% confidence interval of intercepts: copies/ml, −0.52 to −1.01; IU/ml, 0.07 to −0.36). Additionally, Bland-Altman analyses revealed a clinically significant reduction of bias when results were reported in IU/ml (IU/ml, −0.10 log10; copies/ml, −0.70 log10). These results indicate that the use of a common calibrator improved the agreement between the two assays. As clinical laboratories worldwide use calibrators traceable to the primary standard to harmonize BKV NAAT results, we anticipate improved interassay comparisons with a potential for establishing broadly applicable quantitative BKV DNA load cutoffs for clinical practice. PMID:28053213

Hemorrhagic Cystitis due to BK Reactivation in a Young Female Treated for Hodgkin-Disease

PubMed Central

Le Calloch, R.; Ianotto, J. C.; Berthou, C.; Tempescul, A.

2011-01-01

Hodgkin's lymphoma is a disease with a high rate of curability under classic chemo-radiotherapy regimes. Complications due to chemotherapy could include viral reactivation due to chronic lymphopenia. BK virus (BKV) is a polyoma virus belonging to the Papovaviridae family with antibody seroprevalences in healthy populations varying from 60% to 80%. Initial infections are asymptomatic usually occur in early childhood, after which the viruses remain latent in the kidneys or urothelium. Reactivation of BKV occurs in individuals with severe immunosuppression during HIV infections, transplantation or, exceptionally, after classical chemotherapy. BKV incidence is approximately 0% to 5% in immunocompetent individuals. Reactivation is associated with nephropathy and haemorrhagic cystitis. Herein, we present a case of a haemorrhagic cystitis due to BKV reactivation in a patient with Hodgkin's disease treated with chemotherapy. PMID:22937308

Hemorrhagic Cystitis due to BK Reactivation in a Young Female Treated for Hodgkin-Disease.

PubMed

Le Calloch, R; Ianotto, J C; Berthou, C; Tempescul, A

2011-01-01

Hodgkin's lymphoma is a disease with a high rate of curability under classic chemo-radiotherapy regimes. Complications due to chemotherapy could include viral reactivation due to chronic lymphopenia. BK virus (BKV) is a polyoma virus belonging to the Papovaviridae family with antibody seroprevalences in healthy populations varying from 60% to 80%. Initial infections are asymptomatic usually occur in early childhood, after which the viruses remain latent in the kidneys or urothelium. Reactivation of BKV occurs in individuals with severe immunosuppression during HIV infections, transplantation or, exceptionally, after classical chemotherapy. BKV incidence is approximately 0% to 5% in immunocompetent individuals. Reactivation is associated with nephropathy and haemorrhagic cystitis. Herein, we present a case of a haemorrhagic cystitis due to BKV reactivation in a patient with Hodgkin's disease treated with chemotherapy.

Relationship of pretransplantation polyoma BK virus serologic findings and BK viral reactivation after hematopoietic stem cell transplantation.

PubMed

Wong, Anders S Y; Chan, Kwok-Hung; Cheng, Vincent C C; Yuen, Kwok-Yung; Kwong, Yok-Lam; Leung, Anskar Y H

2007-03-15

Reactivation of polyoma BK virus (BKV) infection is consistently associated with hemorrhagic cystitis in persons who undergo hematopoietic stem cell transplantation (HSCT). In this study, we examined the relationship of reactivation of BKV infection with pre-HSCT serologic findings of BKV antibody. Serial urine samples (n=1118) obtained from 140 HSCT recipients were prospectively obtained, and BKV loads were quantified by quantitative polymerase chain reaction. Pre-HSCT anti-BKV immunoglobulin G (IgG) levels were determined by indirect immunofluorescence. In 68 patients, there was significant peaking (i.e., > or = 3-log increase) in the urine BKV load (median peak, 1.7x10(9) copies/mL; range, 1.1x10(4) to 3.2x10(14) copies/mL) occurring at a median time of 24.5 days (range, 7-49 days). In 72 patients, low-level BKV viruria occurred without peaking (median BKV load, 10 copies/mL; range, 9.9x10(3) to 1.2x10(10) copies/mL) at a median time of 24.5 days (range, 7-49 days). Pre-HSCT anti-BKV IgG was positively related to elevated urine BKV load during HSCT (P<.001). Binary logistic regression revealed that pre-HSCT anti-BKV IgG level was the only statistically significant factor (P=.009) to be associated with a > or = 3-log increase in the peak urine BKV load (positive and negative predictive values, 69% and 68%, respectively). Nine patients developed hemorrhagic cystitis at a median of 56 days (range, 29-160); 7 of these patients were evaluable and were found to have a > or = 3-log increase in the peak BKV load. In binary logistic regression, peaking of the urine BKV load (P=.026) and graft-versus-host disease (P=.033) were found to be statistically significant risks for hemorrhagic cystitis. The identification of the serologic status of BKV as a significant risk factor for BKV viruria suggests that it should be included as an integral part of the pre-HSCT evaluation.

Analysis of Surface and Subsurface Damage Morphology in Rotary Ultrasonic Machining of BK7 Glass

NASA Astrophysics Data System (ADS)

Hong-xiang, Wang; Chu, Wang; Jun-liang, Liu; Shi, Gao; Wen-Jie, Zhai

2017-11-01

This paper investigates the formation process of surface/subsurface damage in the rotary ultrasonic machining of BK7 glass. The results show that during the milling using the end face of the tool, the cutting depth and the residual height between the abrasive grains constantly change with the high-frequency vibration, generating lots of cracks on both sides of the scratches. The high-frequency vibration accelerates the chips falling from the surface, so that the chips and thermal damage are reduced, causing the grinding surface quality better. A plastic deformation area is formed during the grinding, due to the non-uniform cutting force on the material surface, and the residual stress is produced in the deformation area, inducing the median/lateral cracks.

Ca2+ block and flickering both contribute to the negative slope of the IV curve in BK channels.

PubMed

Schroeder, Indra; Thiel, Gerhard; Hansen, Ulf-Peter

2013-04-01

Single-channel current-voltage (IV) curves of human large-conductance, voltage- and Ca(2+)-activated K(+) (BK) channels are quite linear in 150 mM KCl. In the presence of Ca(2+) and/or Mg(2+), they show a negative slope conductance at high positive potentials. This is generally explained by a Ca(2+)/Mg(2+) block as by Geng et al. (2013. J. Gen. Physiol. http://dx.doi.org/10.1085/jgp.201210955) in this issue. Here, we basically support this finding but add a refinement: the analysis of the open-channel noise by means of β distributions reveals what would be found if measurements were done with an amplifier of sufficient temporal resolution (10 MHz), namely that the block by 2.5 mM Ca(2+) and 2.5 mM Mg(2+) per se would only cause a saturating curve up to +160 mV. Further bending down requires the involvement of a second process related to flickering in the microsecond range. This flickering is hardly affected by the presence or absence of Ca(2+)/Mg(2+). In contrast to the experiments reported here, previous experiments in BK channels (Schroeder and Hansen. 2007. J. Gen. Physiol. http://dx.doi.org/10.1085/jgp.200709802) showed saturating IV curves already in the absence of Ca(2+)/Mg(2+). The reason for this discrepancy could not be identified so far. However, the flickering component was very similar in the old and new experiments, regardless of the occurrence of noncanonical IV curves.

Experimental Study of Tool Wear and Grinding Forces During BK-7 Glass Micro-grinding with Modified PCD Tool

NASA Astrophysics Data System (ADS)

Pratap, A.; Sahoo, P.; Patra, K.; Dyakonov, A. A.

2017-09-01

This study focuses on the improvement in grinding performance of BK-7 glass using polycrystalline diamond micro-tool. Micro-tools are modified using wire EDM and performance of modified tools is compared with that of as received tool. Tool wear of different types of tools are observed. To quantify the tool wear, a method based on weight loss of tool is introduced in this study. Modified tools significantly reduce tool wear in comparison to the normal tool. Grinding forces increase with machining time due to tool wear. However, modified tools produce lesser forces thus can improve life of the PCD micro-grinding tool.

Relative similarity within purine nucleotide and ligand structures operating on nitric oxide synthetase, guanylyl cyclase and potassium (K ATP, BK Ca) channels.

PubMed

Williams, W Robert

2011-01-01

Purine nucleotides play a central role in signal transduction events initiated at the cell membrane. The NO-cGMP-cGK pathway, in particular, mediates events involving NOS and some classes of K(+) ion channel. The aim of this study is to investigate relative molecular similarity within the ligands binding to NOS, K(ATP), BK(Ca) channels and regulatory nucleotides. Minimum energy conformers of the ligand structures were superimposed and fitted to L-arginine and the nucleotides of adenine and guanine using a computational program. Distinctive patterns were evident in the fitting of NOS isoform antagonists to L-arginine. K(ATP) channel openers and antagonists superimposed on the glycosidic linkage and imidazole ring of the purine nucleotides, and guanidinium and ribose groups of GTP in the case of glibenclamide. The fits of BK(Ca) channel openers and antagonists to cGMP were characterized by the linear dimensions of their structures; distances between terminal oxy groups in respect of dexamethasone and aldosterone. The findings provide structural evidence for the functional interaction between K(+) channel openers/antagonists and the regulatory nucleotides. Use of the purine nucleotide template systematizes the considerable heterogeneity evident within the structures of ligands operating on K(+) ion channels. © 2010 The Author. JPP © 2010 Royal Pharmaceutical Society.

[Clinical significance of monitoring BK polyomavirus in patients after hematopoietic stem cell transplantation].

PubMed

Yin, Chang-Xin; Jiang, Qian-Li; He, Han; Yu, Guo-Pan; Xu, Yue; Meng, Fan-Yi; Yang, Mo

2012-02-01

This study was aimed to establish a method for rapid detecting BK polyomavirus (BKV) and to investigate the feasibility and value used in leukemia patients undergoing hematopoietic stem cell transplantation. Primers were designed according to BKV gene sequence; the quantitative standards for BKV and a real-time fluorescent quantitative PCR for BKV were established. The BKV level in urine samples from 36 patients after hematopoietic stem cell transplantation were detected by established method. The results showed that the standard of reconstructed plasmid and real time fluorescent quantitative PCR method were successfully established, its good specificity, sensitivity and stability were confirmed by experiments. BKV was found in 55.56% of urine samples, and the BKV load in urine was 2.46 × 10(4) - 7.8 × 10(9) copy/ml. It is concluded that the establishment of real-time fluorescent quantitative PCR for BKV detection provides a method for early diagnosis of the patients with hemorrhagic cystitis after hematopoietic stem cell transplantation.

Bladder transitional cell carcinoma and BK virus in a young kidney transplant recipient.

PubMed

Pino, L; Rijo, E; Nohales, G; Frances, A; Ubre, A; Arango, O

2013-02-01

Kidney transplant recipients have a heightened risk of developing neoplasms. Immunosuppressive treatments decrease the incidence of transplant rejection but increase the risk of infections, including BK virus (BKV). This infection is acquired in childhood and remains latent in the renal and urinary epithelium. In cases of immunodeficiency, BKV has been implicated as a tumor virus, but the role of BKV in cancer is a controversial topic and is difficult to determine. In the tumor cells, it is possible to detect fragments of the viral genome that could alter the control mechanisms of the cell cycle and DNA repair. We report the case of a kidney transplant recipient who developed BKV nephropathy and carcinoma of the bladder, supporting a possible role for BKV in the oncogenic pathway in this clinical setting, but the role of BKV in cancer remains a controversial topic and difficult to determine. © 2012 John Wiley & Sons A/S.

Characteristics of polyomavirus BK (BKPyV) infection in primary human urothelial cells.

PubMed

Li, Ruomei; Sharma, Biswa Nath; Linder, Stig; Gutteberg, Tore Jarl; Hirsch, Hans H; Rinaldo, Christine Hanssen

2013-05-25

High-level polyomavirus BK (BKPyV) replication in urothelial cells is a hallmark of polyomavirus-associated hemorrhagic cystitis (PyVHC), a painful condition affecting bone marrow transplant recipients. In kidney transplant recipients, replication in tubular epithelial cells is associated with overt disease whereas high-level urothelial replication is clinically silent. We characterized BKPyV replication in primary human urothelial cells (HUCs) and compared it to replication in renal tubular epithelial cells (RPTECs). HUCs were easily infected, as shown by expression of T-antigens, VP1-3, and agnoprotein, and intranuclear virion production. Compared to RPTECs, progeny release was delayed by ≥24h and reduced. BKPyV-infected HUCs rounded up like "decoy cells" and detached without necrosis as shown by delayed cytokeratin-18 release, real-time viability monitoring and imaging. The data show that BKV infection of HUCs and RPTECs is significantly different and support the notion that PyVHC pathogenesis is not solely due to BKPyV replication, but likely requires urotoxic and immunological cofactors. Copyright © 2013 Elsevier Inc. All rights reserved.

BK virus induced nephritis in a boy with acute myeloid leukaemia undergoing bone marrow transplantation

PubMed Central

Hoefele, Julia; Rüssmann, Despina; Klein, Barbara; Weber, Lutz T.; Führer, Monika

2008-01-01

BK virus (BKV) is a human polyomavirus. The primary infection occurs typically without specific signs or symptoms. Almost 80% of adults are seropositive. Clinically relevant infections are usually limited to individuals who are immunosuppressed. After primary infection, BKV remains latent in the kidneys and can be reactivated in the setting of immunosuppression. BKV is associated with tubulointerstitial nephritis and ureteric stenosis in renal transplant recipients. Furthermore, BKV-induced haemorrhagic cystitis (HC) is a severe complication of bone marrow transplantation (BMT) in children and adults. A combination of HC and tubulointerstitial nephritis in a patient has not been reported so far. We report on an 11-year-old boy with acute myeloid leukaemia undergoing BMT. BKV infection was reactivated during post-transplant immunosuppressive therapy causing HC associated with tubulointerstitial nephritis. PMID:25983928

Association between a high BK virus load in urine samples of patients with graft-versus-host disease and development of hemorrhagic cystitis after hematopoietic stem cell transplantation.

PubMed

Bogdanovic, G; Priftakis, P; Giraud, G; Kuzniar, M; Ferraldeschi, R; Kokhaei, P; Mellstedt, H; Remberger, M; Ljungman, P; Winiarski, J; Dalianis, T

2004-11-01

BK virus (BKV) load in urine alone or in combination with acute graft-versus-host disease (GVHD) was correlated to development of hemorrhagic cystitis (HC). BKV load in combination with acute GVHD discriminated the best, while BKV and viral load alone, but not GVHD, still showed predictive ability for HC.

Conversion of the high-yield salinomycin producer Streptomyces albus BK3-25 into a surrogate host for polyketide production.

PubMed

Zhang, Xiaojie; Lu, Chenyang; Bai, Linquan

2017-09-01

An ideal surrogate host for heterologous production of various natural products is expected to have efficient nutrient utilization, fast growth, abundant precursors and energy supply, and a pronounced gene expression. Streptomyces albus BK3-25 is a high-yield industrial strain producing type-I polyketide salinomycin, with a unique ability of bean oil utilization. Its potential of being a surrogate host for heterologous production of PKS was engineered and evaluated herein. Firstly, introduction of a three-gene cassette for the biosynthesis of ethylmalonyl-CoA resulted in accumulation of ethylmalonyl-CoA precursor and salinomycin, and subsequent deletion of the salinomycin biosynthetic gene cluster resulted in a host with rich supplies of common polyketide precursors, including malonyl-CoA, methylmalonyl-CoA, and ethylmalonyl-CoA. Secondly, the energy and reducing force were measured, and the improved accumulation of ATP and NADPH was observed in the mutant. Furthermore, the strength of a series of selected endogenous promoters based on microarray data was assessed at different growth phases, and a strong constitutive promoter was identified, providing a useful tool for further engineered gene expression. Finally, the potential of the BK3-25 derived host ZXJ-6 was evaluated with the introduction of the actinorhodin biosynthetic gene cluster from Streptomyces coelicolor, and the heterologous production of actinorhodin was obtained. This work clearly indicated the potential of the high-yield salinomycin producer as a surrogate host for heterologous production of polyketides, although more genetic manipulation should be conducted to streamline its performance.

BK Lyncis: the oldest old nova and a Bellwether for cataclysmic variable evolution

NASA Astrophysics Data System (ADS)

Patterson, Joseph; Uthas, Helena; Kemp, Jonathan; de Miguel, Enrique; Krajci, Thomas; Foote, Jerry; Hambsch, Franz-Josef; Campbell, Tut; Roberts, George; Cejudo, David; Dvorak, Shawn; Vanmunster, Tonny; Koff, Robert; Skillman, David; Harvey, David; Martin, Brian; Rock, John; Boyd, David; Oksanen, Arto; Morelle, Etienne; Ulowetz, Joseph; Kroes, Anthony; Sabo, Richard; Jensen, Lasse

2013-09-01

We summarize the results of a 20-yr campaign to study the light curves of BK Lyn, a nova-like star strangely located below the 2 to 3 h orbital-period gap in the family of cataclysmic variables (CVs). Two apparent superhumps dominate the nightly light curves, with periods 4.6 per cent longer, and 3.0 per cent shorter, than the orbital period. The first appears to be associated with the star's brighter states (V ˜ 14), while the second appears to be present throughout and becomes very dominant in the low state (V ˜ 15.7). It is plausible that these arise, respectively, from a prograde apsidal precession and a retrograde nodal precession of the star's accretion disc. Starting in the year 2005, the star's light curve became indistinguishable from that of a dwarf nova - in particular, that of the ER UMa subclass. No such clear transition has ever been observed in a CV before. Reviewing all the star's oddities, we speculate: (a) BK Lyn is the remnant of the probable nova on 101 December 30, and (b) it has been fading ever since, but it has taken ˜2000 yr for the accretion rate to drop sufficiently to permit dwarf-nova eruptions. If such behaviour is common, it can explain other puzzles of CV evolution. One: why the ER UMa class even exists (because all members can be remnants of recent novae). Two: why ER UMa stars and short-period nova-likes are rare (because their lifetimes, which are essentially cooling times, are short). Three: why short-period novae all decline to luminosity states far above their true quiescence (because they are just getting started in their post-nova cooling). Four: why the orbital periods, accretion rates and white dwarf temperatures of short-period CVs are somewhat too large to arise purely from the effects of gravitational radiation (because the unexpectedly long interval of enhanced post-nova brightness boosts the mean mass-transfer rate). And maybe even five: why very old, post-period-bounce CVs are hard to find (because the higher mass

BK virus-associated fatal renal failure following late-onset hemorrhagic cystitis in an unrelated bone marrow transplantation.

PubMed

Iwamoto, Shotaro; Azuma, Eiichi; Hori, Hiroki; Hirayama, Masahiro; Kobayashi, Michihiro; Komada, Yoshihiro; Nishimori, Hisashi; Miyahara, Masazumi

2002-06-01

The human polyomavirus BK (BKV)-associated hemorrhagic cystitis (HC) has been a frequent and, seldom life-threatening complication after bone marrow transplantation (BMT). The authors report a male with melodysplastic syndrome, who developed BKV-associated late-onset HC 12 days after HLA-matched unrelated BMT. His urine contained epithelial cells with intranuclear inclusion bodies suggestive of BKV infection and was positive for BKV in polymerase chain reaction. He did not respond to any treatment for HC. In addition, he developed BKV-associated acute renal failure on day 26, followed by hepatic veno-occlusive disease on day 42. This is the first case in which BKV may be associated with fatal progressive renal failure.

Association between a High BK Virus Load in Urine Samples of Patients with Graft-Versus-Host Disease and Development of Hemorrhagic Cystitis after Hematopoietic Stem Cell Transplantation

PubMed Central

Bogdanovic, G.; Priftakis, P.; Giraud, G.; Kuzniar, M.; Ferraldeschi, R.; Kokhaei, P.; Mellstedt, H.; Remberger, M.; Ljungman, P.; Winiarski, J.; Dalianis, T.

2004-01-01

BK virus (BKV) load in urine alone or in combination with acute graft-versus-host disease (GVHD) was correlated to development of hemorrhagic cystitis (HC). BKV load in combination with acute GVHD discriminated the best, while BKV and viral load alone, but not GVHD, still showed predictive ability for HC. PMID:15528753

Ultrasonic vibration double scratch morphology and scratching force of BK7 glass

NASA Astrophysics Data System (ADS)

Wang, Chu; Wang, Hongxiang; Liu, Junliang; Gao, Shi

2018-03-01

In this paper, the damage morphology and scratching force of BK7 glass components were analyzed by ultrasonic vibration double-scratch test. The results showed that there was surface damage caused by plastic flow and brittle fracture during the scratching process, and the scratching depth and the distance between the two scratches had effect on the propagation and overlapping of lateral cracks. When the scratching depth was small, the jagged scratch was produced on the surface, and accompanied by a small amount of tiny pieces of debris off. With the increase in scratching depth, the lateral cracks caused by scratching overlapped and expended to form a mesh sheet, and then fell off from the surface. When the scratching distance was small, the interaction of the cracks caused large slice of material to fall off. With the increase in scratching distance, the area between the two scratches was not easy to occur the overlapping of the lateral cracks. In addition, with the increase of the scratching depth, the scratching force showed a gradual increase trend, and the scratching force of the second scratch would increase with the scratching distance.

Rapid detection of urinary polyomavirus BK by heterodyne-based surface plasmon resonance biosensor

NASA Astrophysics Data System (ADS)

Su, Li-Chen; Tian, Ya-Chung; Chang, Ying-Feng; Chou, Chien; Lai, Chao-Sung

2014-01-01

In renal transplant patients, immunosuppressive therapy may result in the reactivation of polyomavirus BK (BKV), leading to polyomavirus-associated nephropathy (PVAN), which inevitably causes allograft failure. Since the treatment outcomes of PVAN remain unsatisfactory, early identification and continuous monitoring of BKV reactivation and reduction of immunosuppressants are essential to prevent PVAN development. The present study demonstrated that the developed dual-channel heterodyne-based surface plasmon resonance (SPR) biosensor is applicable for the rapid detection of urinary BKV. The use of a symmetrical reference channel integrated with the poly(ethylene glycol)-based low-fouling self-assembled monolayer to reduce the environmental variations and the nonspecific noise was proven to enhance the sensitivity in urinary BKV detection. Experimentally, the detection limit of the biosensor for BKV detection was estimated to be around 8500 copies/mL. In addition, urine samples from five renal transplant patients were tested to rapidly distinguish PVAN-positive and PVAN-negative renal transplant patients. By virtue of its simplicity, rapidity, and applicability, the SPR biosensor is a remarkable potential to be used for continuous clinical monitoring of BKV reactivation.

"Legal highs"--toxicity in the clinical and medico-legal aspect as exemplified by suicide with bk-MBDB administration.

PubMed

Rojek, Sebastian; Kłys, Małgorzata; Strona, Marcin; Maciów, Martyna; Kula, Karol

2012-10-10

The easily available "legal highs", which are products containing psychoactive substances, such as cathinones, piperazines and synthetic cannabinoids, are abused by adolescents in Poland and in the world as alternatives to classic drugs, such as amphetamines or marijuana. The majority of these potentially dangerous substances are still legal and they are associated with a risk of severe poisoning or even death, and provide new challenges in clinical and forensic toxicological practice. Investigations in the field of "designer drugs" may be well illustrated by the case of a suicide of a 21-year old male who ingested a specified dose of a preparation called "Amphi-bi-a" that contains bk-MBDB, chemically 2-methylamino-1-(3,4-methylenedioxyphenyl) butan-1-one, which belongs to the cathinone group, as a synthetic euphoric empathogen and psychoactive stimulant that is chemically similar to MDMA. It is one of more common components of "legal highs" examined in Poland and other countries. The documentation of the case includes a clinical assessment of the patient's health status performed during his almost 4-h hospitalization before death, autopsy and histological examinations supported by toxicological findings revealing bk-MBDB at extremely high concentrations (at 20 mg/l in the blood and 33 mg/kg in the liver); hence, this body of evidence contributes to knowledge in the field of "designer drugs". Inventions of designers of new psychoactive xenobiotics, which are much in demand, especially in view of the dynamic Internet marketing, which drums up narcobusiness, must be balanced by a national strategy developed by medical, legal and educational circles in the modern civilized world in order to prevent the spreading of the phenomenon. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Successful Treatment of BK Virus Hemorrhagic Cystitis (HC) Post Allogenic Hematopoietic Stem Cell Transplantation with Low Dose Cidofovir.

PubMed

Arora, R; Jasmita; Singh, M; Garg, A; Gupta, M; Gupta, N

2017-05-01

BK virus (BKV) hemorrhagic cystitis (HC) is a serious cause of morbidity and mortality after allogeneic hematopoietic SCT (allo-HSCT) in patients with hematological malignancies. Around half of allogenic HSCT patients present with BKV viruria at some point after HSCT; about 5-40% of these patients subsequently develop active HC. Supportive care including bladder irrigation, blood transfusions and symptomatic pain management remains the mainstay of therapy; the acyclic nucleoside analogue cidofovir is currently the front-line drug for BKV-HC treatment. Here we report the first case of severe hemorrhagic cystitis from India who was successfully treated with low dose cidofovir therapy. © Journal of the Association of Physicians of India 2011.

Cytomegalovirus and BK-Virus co-infection of a clinically non-functioning adrenal adenoma: innocent bystanders or new pathogenetic agents?

PubMed

Pomara, G; Cappello, F; Barzon, L; Morelli, G; Rappa, F; Benvegna, L; Giannarini, G; Palù, G; Selli, C

2006-01-01

We report a case of a 64-year-old woman who underwent left adrenalectomy with removal of a 8,5 cm clinically non-functioning adrenocortical adenoma and a 4-cm myelolipoma. Molecular testing for viral infection demonstrated the presence of cytomegalovirus (CMV) DNA sequences in the adrenal adenoma, but not in the myelolipoma (confirmed by immunohistochemistry). Moreover, the adrenal adenoma was also positive for parvovirus B19, and both adrenal tumor samples were positive for polyomavirus BK (BKV) and adenovirus DNA sequences. This is the first report of co-infection of an adrenocortical adenoma by CMV and BKV. The role of these viruses in adrenal tumorigenesis was postulated.

Successful hyperbaric oxygen therapy for refractory BK virus-associated hemorrhagic cystitis after cord blood transplantation.

PubMed

Hosokawa, K; Yamazaki, H; Nakamura, T; Yoroidaka, T; Imi, T; Shima, Y; Ohata, K; Takamatsu, H; Kotani, T; Kondo, Y; Takami, A; Nakao, S

2014-10-01

BK virus-associated hemorrhagic cystitis (BKV-HC) is a common and major cause of morbidity in recipients of allogeneic hematopoietic stem cell transplantation. A 32-year-old woman developed severe BKV-HC on day 24 after cord blood transplantation (CBT). Despite supportive therapies - such as hyperhydration, forced diuresis, and urinary catheterization - macroscopic hematuria and bladder irritation persisted for over a month. Hyperbaric oxygen (HBO) therapy at 2.1 atmospheres for 90 min per day was started on day 64 after CBT. Macroscopic hematuria resolved within a week, and microscopic hematuria was no longer detectable within 2 weeks. Hematuria did not recur after 11 sessions of HBO therapy, and no significant side effects were observed during or after treatment. HBO therapy could thus be useful in controlling refractory BKV-HC after CBT. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Spatially resolving the outer atmosphere of the M giant BK Virginis in the CO first overtone lines with VLTI/AMBER

NASA Astrophysics Data System (ADS)

Ohnaka, K.; Hofmann, K.-H.; Schertl, D.; Weigelt, G.; Malbet, F.; Massi, F.; Meilland, A.; Stee, Ph.

2012-01-01

Context. The mass-loss mechanism in normal K-M giant stars with small variability amplitudes is not yet understood, although the majority among red giant stars are precisely of this type. Aims: We present high-spatial and high-spectral resolution observations of the M7 giant BK Vir with AMBER at the Very Large Telescope Interferometer (VLTI). Our aim is to probe the physical properties of the outer atmosphere by spatially resolving the star in the individual CO first overtone lines. Methods: BK Vir was observed between 2.26 and 2.31 μm using the 16-32-48 m telescope configuration with an angular resolution of 9.8 mas and a spectral resolution of 12 000. Results: The uniform-disk diameters observed in the CO first overtone lines are 12 - 31% larger than those measured in the continuum. We also detected asymmetry in the CO line-forming region, which manifests itself as non-zero/non-π differential and closure phases. The data taken 1.5 months apart show possible time variation on a spatial scale of 30 mas (corresponding to 3 × stellar diameter) at the CO band head. Comparison of the observed data with the MARCS photospheric model shows that whereas the observed CO line spectrum can be satisfactorily reproduced by the model, the angular sizes observed in the CO lines are much larger than predicted by the model. Our model with two additional CO layers above the MARCS photosphere reproduces the observed spectrum and interferometric data in the CO lines simultaneously. This model suggests that the inner CO layer at ~1.2 R⋆ is very dense and warm with a CO column density of ~1022 cm-2 and temperatures of 1900 - 2100 K, while the outer CO layer at 2.5-3.0 R⋆ is characterized by column densities of 1019-1020 cm-2 and temperatures of 1500 - 2100 K. Conclusions: Our AMBER observations of BK Vir have spatially resolved the extended molecular outer atmosphere of a normal M giant in the individual CO lines for the first time. The temperatures derived for the CO layers are

Viral drug sensitivity testing using quantitative PCR: effect of tyrosine kinase inhibitors on polyomavirus BK replication.

PubMed

Randhawa, Parmjeet S; Farasati, Noush A; Huang, Yuchen; Mapara, Markus Y; Shapiro, Ron

2010-12-01

Our objective was to determine whether quantitative polymerase chain reaction (PCR) can be used to measure the effect of tyrosine kinase (TK) inhibition on polyomavirus BK (BKV) replication. The BKV was grown in a cell culture system. The rate of viral replication in the presence or absence of the drug being tested was assessed by amplifying the viral genome using primers directed against the viral capsid 1 protein. Dasatinib, erlotinib, gefitinib, imatinib, sunitinib, and sorafenib all showed antiviral activity at micromolar concentrations. The 50% effective concentration for erlotinib and sorafenib was within blood concentrations readily achieved in human subjects. Quantitative PCR is a convenient method for viral drug sensitivity testing for slow-growing viruses that do not readily produce cytopathic effect. TK inhibitors deserve further consideration as a potential therapeutic option for BKV-associated nephropathy and hemorrhagic cystitis.

Unique BK virus non-coding control region (NCCR) variants in hematopoietic stem cell transplant recipients with and without hemorrhagic cystitis.

PubMed

Carr, Michael J; McCormack, Grace P; Mutton, Ken J; Crowley, Brendan

2006-04-01

Hematopoietic stem cell transplant recipients frequently develop BK virus (BKV)-associated hemorrhagic cystitis, which coincides with BK viruria. However, the precise role of BKV in the etiology of hemorrhagic cystitis in hematopoietic stem cell transplant recipients remains unclear, since approximately 50% of all such adult transplant recipients excrete BKV, yet do not develop this clinical condition. In the present study, BKV were analyzed to determine if mutations in the non-coding control region (NCCR), and specific BKV sub-types defined by sequence analysis of major capsid protein VP1, were associated with development of hemorrhagic cystitis in hematopoietic stem cell transplant recipients. The regions encoding VP1 and NCCRs of BKV in urine samples collected from 15 hematopoietic stem cell transplant recipients with hemorrhagic cystitis and 20 without this illness were amplified and sequenced. Sequence variations in the NCCRs of BKV were identified in urine samples from those with and without hemorrhagic cystitis. Furthermore, five unique sequence variations within transcription factor binding sites in the canonical NCCR, O-P-Q-R-S, were identified, representing new BKV variants from a population of cloned quasi-species obtained from patients with and without hemorrhagic cystitis. Thirty-five BKV VP1 sequences were analyzed by phylogenetic analysis but no specific BKV sub-type was associated with hemorrhagic cystitis. Five previously unrecognized naturally occurring variants of the BKV are described which involve amplifications, deletions, and rearrangements of the archetypal BKV NCCRs in individuals with and without hemorrhagic cystitis. Architectural rearrangements in the NCCRs of BKV did not appear to be a prerequisite for development of hemorrhagic cystitis in hematopoietic stem cell transplant recipients. Copyright 2006 Wiley-Liss, Inc.

Expression of a Diverse Array of Ca2+-Activated K+ Channels (SK1/3, IK1, BK) that Functionally Couple to the Mechanosensitive TRPV4 Channel in the Collecting Duct System of Kidney.

PubMed

Li, Yue; Hu, Hongxiang; Butterworth, Michael B; Tian, Jin-Bin; Zhu, Michael X; O'Neil, Roger G

2016-01-01

The voltage- and Ca2+-activated, large conductance K+ channel (BK, maxi-K) is expressed in the collecting duct system of kidney where it underlies flow- and Ca2+-dependent K+ excretion. To determine if other Ca2+-activated K+ channels (KCa) may participate in this process, mouse kidney and the K+-secreting mouse cortical collecting duct (CCD) cell line, mCCDcl1, were assessed for TRPV4 and KCa channel expression and cross-talk. qPCR mRNA analysis and immunocytochemical staining demonstrated TRPV4 and KCa expression in mCCDcl1 cells and kidney connecting tubule (CNT) and CCD. Three subfamilies of KCa channels were revealed: the high Ca2+-binding affinity small-conductance SK channels, SK1and SK3, the intermediate conductance channel, IK1, and the low Ca2+-binding affinity, BK channel (BKα subunit). Apparent expression levels varied in CNT/CCD where analysis of CCD principal cells (PC) and intercalated cells (IC) demonstrated differential staining: SK1:PCIC, IK1:PC>IC, BKα:PC = IC, and TRPV4:PC>IC. Patch clamp analysis and fluorescence Ca2+ imaging of mCCDcl1 cells demonstrated potent TRPV4-mediated Ca2+ entry and strong functional cross-talk between TRPV4 and KCa channels. TRPV4-mediated Ca2+ influx activated each KCa channel, as evidenced by selective inhibition of KCa channels, with each active KCa channel enhancing Ca2+ entry (due to membrane hyperpolarization). Transepithelial electrical resistance (TEER) analysis of confluent mCCDcl1 cells grown on permeable supports further demonstrated this cross-talk where TRPV4 activation induce a decrease in TEER which was partially restored upon selective inhibition of each KCa channel. It is concluded that SK1/SK3 and IK1 are highly expressed along with BKα in CNT and CCD and are closely coupled to TRPV4 activation as observed in mCCDcl1 cells. The data support a model in CNT/CCD segments where strong cross talk between TRPV4-mediated Ca2+ influx and each KCa channel leads to enhance Ca2+ entry which

No Evidence for Infection of UK Prostate Cancer Patients with XMRV, BK Virus, Trichomonas vaginalis or Human Papilloma Viruses

PubMed Central

Groom, Harriet C. T.; Warren, Anne Y.; Neal, David E.; Bishop, Kate N.

2012-01-01

The prevalence of specific infections in UK prostate cancer patients was investigated. Serum from 84 patients and 62 controls was tested for neutralisation of xenotropic murine leukaemia virus-related virus (XMRV) Envelope. No reactivity was found in the patient samples. In addition, a further 100 prostate DNA samples were tested for XMRV, BK virus, Trichomonas vaginalis and human papilloma viruses by nucleic acid detection techniques. Despite demonstrating DNA integrity and assay sensitivity, we failed to detect the presence of any of these agents in DNA samples, bar one sample that was weakly positive for HPV16. Therefore we conclude that these infections are absent in this typical cohort of men with prostate cancer. PMID:22470540

No evidence for infection of UK prostate cancer patients with XMRV, BK virus, Trichomonas vaginalis or human papilloma viruses.

PubMed

Groom, Harriet C T; Warren, Anne Y; Neal, David E; Bishop, Kate N

2012-01-01

The prevalence of specific infections in UK prostate cancer patients was investigated. Serum from 84 patients and 62 controls was tested for neutralisation of xenotropic murine leukaemia virus-related virus (XMRV) Envelope. No reactivity was found in the patient samples. In addition, a further 100 prostate DNA samples were tested for XMRV, BK virus, Trichomonas vaginalis and human papilloma viruses by nucleic acid detection techniques. Despite demonstrating DNA integrity and assay sensitivity, we failed to detect the presence of any of these agents in DNA samples, bar one sample that was weakly positive for HPV16. Therefore we conclude that these infections are absent in this typical cohort of men with prostate cancer.

BK Polyomavirus Genotypes Represent Distinct Serotypes with Distinct Entry Tropism

PubMed Central

Pastrana, Diana V.; Ray, Upasana; Magaldi, Thomas G.; Schowalter, Rachel M.; Çuburu, Nicolas

2013-01-01

BK polyomavirus (BKV) causes significant urinary tract pathogenesis in immunosuppressed individuals, including kidney and bone marrow transplant recipients. It is currently unclear whether BKV-neutralizing antibodies can moderate or prevent BKV disease. We developed reporter pseudoviruses based on seven divergent BKV isolates and performed neutralization assays on sera from healthy human subjects. The results demonstrate that BKV genotypes I, II, III, and IV are fully distinct serotypes. While nearly all healthy subjects had BKV genotype I-neutralizing antibodies, a majority of subjects did not detectably neutralize genotype III or IV. Surprisingly, BKV subgenotypes Ib1 and Ib2 can behave as fully distinct serotypes. This difference is governed by as few as two residues adjacent to the cellular glycan receptor-binding site on the virion surface. Serological analysis of mice given virus-like particle (VLP)-based BKV vaccines confirmed these findings. Mice administered a multivalent VLP vaccine showed high-titer serum antibody responses that potently cross-neutralized all tested BKV genotypes. Interestingly, each of the neutralization serotypes bound a distinct spectrum of cell surface receptors, suggesting a possible connection between escape from recognition by neutralizing antibodies and cellular attachment mechanisms. The finding implies that different BKV genotypes have different cellular tropisms and pathogenic potentials in vivo. Individuals who are infected with one BKV serotype may remain humorally vulnerable to other BKV serotypes after implementation of T cell immunosuppression. Thus, prevaccinating organ transplant recipients with a multivalent BKV VLP vaccine might reduce the risk of developing posttransplant BKV disease. PMID:23843634

Positions of the cytoplasmic end of BK α S0 helix relative to S1–S6 and of β1 TM1 and TM2 relative to S0–S6

PubMed Central

Liu, Guoxia; Zakharov, Sergey I.; Yao, Yongneng

2015-01-01

The large-conductance, voltage- and Ca2+-gated K+ (BK) channel consists of four α subunits, which form a voltage- and Ca2+-gated channel, and up to four modulatory β subunits. The β1 subunit is expressed in smooth muscle, where it slows BK channel kinetics and shifts the conductance–voltage (G-V) curve to the left at [Ca2+] > 2 µM. In addition to the six transmembrane (TM) helices, S1–S6, conserved in all voltage-dependent K+ channels, BK α has a unique seventh TM helix, S0, which may contribute to the unusual rightward shift in the G-V curve of BK α in the absence of β1 and to a leftward shift in its presence. Such a role is supported by the close proximity of S0 to S3 and S4 in the voltage-sensing domain. Furthermore, on the extracellular side of the membrane, one of the two TM helices of β1, TM2, is adjacent to S0. We have now analyzed induced disulfide bond formation between substituted Cys residues on the cytoplasmic side of the membrane. There, in contrast, S0 is closest to the S2–S3 loop, from which position it is displaced on the addition of β1. The cytoplasmic ends of β1 TM1 and TM2 are adjacent and are located between the S2–S3 loop of one α subunit and S1 of a neighboring α subunit and are not adjacent to S0; i.e., S0 and TM2 have different trajectories through the membrane. In the absence of β1, 70% of disulfide bonding of W43C (S0) and L175C (S2–S3) has no effect on V50 for activation, implying that the cytoplasmic end of S0 and the S2–S3 loop move in concert, if at all, during activation. Otherwise, linking them together in one state would obstruct the transition to the other state, which would certainly change V50. PMID:25667410

Evaluation and utilization of preassembled frozen commercial fast real-time qPCR master mixes for detection of cytomegalovirus and BK virus.

PubMed

Glover, William A; Atienza, Ederlyn E; Nesbitt, Shannon; Kim, Woo J; Castor, Jared; Cook, Linda; Jerome, Keith R

2016-01-01

Quantitative DNA detection of cytomegalovirus (CMV) and BK virus (BKV) is critical in the management of transplant patients. Quantitative laboratory-developed procedures for CMV and BKV have been described in which much of the processing is automated, resulting in rapid, reproducible, and high-throughput testing of transplant patients. To increase the efficiency of such assays, the performance and stability of four commercial preassembled frozen fast qPCR master mixes (Roche FastStart Universal Probe Master Mix with Rox, Bio-Rad SsoFast Probes Supermix with Rox, Life Technologies TaqMan FastAdvanced Master Mix, and Life Technologies Fast Universal PCR Master Mix), in combination with in-house designed primers and probes, was evaluated using controls and standards from standard CMV and BK assays. A subsequent parallel evaluation using patient samples was performed comparing the performance of freshly prepared assay mixes versus aliquoted frozen master mixes made with two of the fast qPCR mixes (Life Technologies TaqMan FastAdvanced Master Mix, and Bio-Rad SsoFast Probes Supermix with Rox), chosen based on their performance and compatibility with existing PCR cycling conditions. The data demonstrate that the frozen master mixes retain excellent performance over a period of at least 10 weeks. During the parallel testing using clinical specimens, no difference in quantitative results was observed between the preassembled frozen master mixes and freshly prepared master mixes. Preassembled fast real-time qPCR frozen master mixes perform well and represent an additional strategy laboratories can implement to reduce assay preparation times, and to minimize technical errors and effort necessary to perform clinical PCR. © 2015 Wiley Periodicals, Inc.

Prevalence of BK virus replication among recipients of solid organ transplants.

PubMed

Muñoz, Patricia; Fogeda, Marta; Bouza, Emilio; Verde, Eduardo; Palomo, Jesus; Bañares, Rafael

2005-12-15

BK virus (BKV) has been implicated as a cause of nephritis and graft loss in 2%-9% of kidney transplant recipients, but the prevalence among recipients of other solid organ transplants (SOTs) has not been well established. Our objective was to determine the prevalence of BKV infection for all types of SOT recipients at our medical center. A total of 156 consecutive SOT recipients were studied, of whom 49 received kidney transplants, 43 received heart transplants, and 64 received liver transplants. Samples were obtained a median of 559 days (range, 1-9481 days) after transplantation. Nested polymerase chain reaction was performed for detection of BKV DNA in urine and plasma specimens. BKV was found in 19% of urine specimens and 6% of plasma specimens. The prevalence of viruria after kidney, heart, and liver transplantation was 26.5%, 25.5%, and 7.8%, respectively. BKV viremia was detected in 12.2% of kidney transplant recipients and 7% of heart transplant recipients. Mean creatinine levels were higher in patients with BKV viruria or viremia (1.9 and 3.5 mg/dL, respectively) than in patients with no BKV replication (1.3 mg/dL). Independent factors related to impaired renal function were renal transplantation (odds ratio [OR], 14.4); BKV replication, including viruria or viremia (OR, 3.3); and mycophenolate use (OR, 2.6). BKV is common in all types of SOT recipients, particularly those who have received heart or kidney transplants.

Cidofovir for BK virus-associated hemorrhagic cystitis: a retrospective study.

PubMed

Cesaro, Simone; Hirsch, Hans H; Faraci, Maura; Owoc-Lempach, Joanna; Beltrame, Angela; Tendas, Andrea; Baltadakis, Ioannis; Dalle, Jean-Hughes; Koc, Yener; Toporski, Jacek; Styczynski, Jan; Yesilipek, M Akif; Heinz, Werner; Caniglia, Maurizio; Rascon, Jelena; Fauser, Axel A; Michallet, Mauricette; Lopez-Corral, Lucia; Neuburger, Stefan; Tridello, Gloria; Einsele, Herman

2009-07-15

BK virus-associated hemorrhagic cystitis (BKV-HC) is a severe complication after allogeneic hematopoietic stem cell transplantation (HSCT), but antiviral treatment for this condition has not been evaluated. We conducted a retrospective survey on the safety and outcome of cidofovir treatment for patients with BKV-HC in centers affiliated with the European Group for Blood and Marrow Transplantation. From 1 April 2004 to 31 December 2007, 62 patients received a diagnosis of BKV-HC after a median interval of 35 days after HSCT (range, 3-577 days). Fifty-seven patients (92%) received intravenous cidofovir, whereas 5 patients received cidofovir intravesically. Complete response (CR) was recorded in 38 (67%) of 57 patients with HC treated with intravenous cidofovir, whereas partial response (PR) was documented in 7 patients (12%). CR was documented in 3 patients and PR in 1 patient with HC treated with intravesical cidofovir. A reduction of 1-3 logs in BKV load was documented in 8 of the 10 patients achieving CR. Mild-to-moderate toxic effects were recorded in 18 of 57 patients who received intravenous cidofovir administration. In a multivariate analysis, the factors significantly associated with response to cidofovir were the stem cell source (P = .01) and the use of total body irradiation (P = .03). After a median follow-up of 287 days, overall survival and total treatment-related mortality rates were 63% and 40% for patients achieving CR, compared with 14% and 72% for patients with PR or no response to cidofovir, respectively (P = .001 and P = .001, respectively). Cidofovir may be a potentially effective therapy for BKV-HC, but evidence supporting its use requires randomized controlled trials.

Neutralization Serotyping of BK Polyomavirus Infection in Kidney Transplant Recipients

PubMed Central

Pastrana, Diana V.; Brennan, Daniel C.; Çuburu, Nicolas; Storch, Gregory A.; Viscidi, Raphael P.; Randhawa, Parmjeet S.; Buck, Christopher B.

2012-01-01

BK polyomavirus (BKV or BKPyV) associated nephropathy affects up to 10% of kidney transplant recipients (KTRs). BKV isolates are categorized into four genotypes. It is currently unclear whether the four genotypes are also serotypes. To address this issue, we developed high-throughput serological assays based on antibody-mediated neutralization of BKV genotype I and IV reporter vectors (pseudoviruses). Neutralization-based testing of sera from mice immunized with BKV-I or BKV-IV virus-like particles (VLPs) or sera from naturally infected human subjects revealed that BKV-I specific serum antibodies are poorly neutralizing against BKV-IV and vice versa. The fact that BKV-I and BKV-IV are distinct serotypes was less evident in traditional VLP-based ELISAs. BKV-I and BKV-IV neutralization assays were used to examine BKV type-specific neutralizing antibody responses in KTRs at various time points after transplantation. At study entry, sera from 5% and 49% of KTRs showed no detectable neutralizing activity for BKV-I or BKV-IV neutralization, respectively. By one year after transplantation, all KTRs were neutralization seropositive for BKV-I, and 43% of the initially BKV-IV seronegative subjects showed evidence of acute seroconversion for BKV-IV neutralization. The results suggest a model in which BKV-IV-specific seroconversion reflects a de novo BKV-IV infection in KTRs who initially lack protective antibody responses capable of neutralizing genotype IV BKVs. If this model is correct, it suggests that pre-vaccinating prospective KTRs with a multivalent VLP-based vaccine against all BKV serotypes, or administration of BKV-neutralizing antibodies, might offer protection against graft loss or dysfunction due to BKV associated nephropathy. PMID:22511874

Clinical polyomavirus BK variants with agnogene deletion are non-functional but rescued by trans-complementation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Myhre, Marit Renee; Olsen, Gunn-Hege; Gosert, Rainer

High-level replication of polyomavirus BK (BKV) in kidney transplant recipients is associated with the emergence of BKV variants with rearranged (rr) non-coding control region (NCCR) increasing viral early gene expression and cytopathology. Cloning and sequencing revealed the presence of a BKV quasispecies which included non-functional variants when assayed in a recombinant virus assay. Here we report that the rr-NCCR of BKV variants RH-3 and RH-12, both bearing a NCCR deletion including the 5' end of the agnoprotein coding sequence, mediated early and late viral reporter gene expression in kidney cells. However, in a recombinant virus they failed to produce infectiousmore » progeny despite large T-antigen and VP1 expression and the formation of nuclear virus-like particles. Infectious progeny was generated when the agnogene was reconstructed in cis or agnoprotein provided in trans from a co-existing BKV rr-NCCR variant. We conclude that complementation can rescue non-functional BKV variants in vitro and possibly in vivo.« less

BK virus DNA detection by real-time polymerase chain reaction in clinical specimens.

PubMed

Marchetti, Simona; Graffeo, Rosalia; Siddu, Alessia; Santangelo, Rosaria; Ciotti, Marco; Picardi, Alessandra; Favalli, Cartesio; Fadda, Giovanni; Cattani, Paola

2007-04-01

The BK polyomavirus (BKV) is widespread in the general population. In transplant recipients, the patients' weakened immune response may encourage reactivation of latent infection, leading to BKV-related diseases. Rapid and quantitative detection might help to delineate viral reactivation patterns and could thus play an important role in their clinical management. In our study we developed an "in-house" quantitative real-time PCR to detect BKV DNA. The effectiveness of this assay was evaluated by a retrospective analysis of 118 plasma specimens from 22 bone marrow transplant (BMT) recipients and 107 samples from immunocompetent subjects. Eight (36.3%) of the 22 bone marrow transplant recipients tested positive for BKV. The viral load varied from specimen to specimen (10 to 10(5) copies/ml). BKV related disease like hemorrhagic cystitis (HC) was diagnosed in three patients. Specimens from the control group all tested negative. Our results showed the high sensitivity of the real-time PCR, allowing accurate and reproducible measuring of the viral load in order to identify patients at risk for BKV-related diseases. With due caution in interpreting threshold values, the real-time PCR could provide a rapid, sensitive and specific tool for detecting BKV and distinguishing latent and active infection.

Optimization, purification, and characterization of L-asparaginase from Actinomycetales bacterium BkSoiiA.

PubMed

Dash, Chitrangada; Mohapatra, Sukanti Bala; Maiti, Prasanta Kumar

2016-01-01

Actinobacteria are promising source of a wide range of important enzymes, some of which are produced in industrial scale, with others yet to be harnessed. L-Asparaginase is used as an antineoplastic agent. The present work deals with the production and optimization of L-asparaginase from Actinomycetales bacterium BkSoiiA using submerged fermentation in M9 medium. Production optimization resulted in a modified M9 medium with yeast extract and fructose as carbon and nitrogen sources, respectively, at pH 8.0, incubated for 120 hr at 30 ± 2 °C. The crude enzyme was purified to near homogeneity by ammonium sulfate precipitation following dialysis, ion-exchange column chromatography, and finally gel filtration. The sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) revealed an apparent molecular weight of 57 kD. The enzyme was purified 95.06-fold and showed a final specific activity of 204.37 U/mg with 3.49% yield. The purified enzyme showed maximum activity at a pH 10.0 and was stable at pH 7.0 to 9.0. The enzyme was activated by Mn(2+) and strongly inhibited by Ba(2+). All these preliminary characterization suggests that the L-asparaginase from the source may be a tool useful to pharmaceutical industries after further research.

Clinical effectiveness of hyperbaric oxygen therapy for BK-virus-associated hemorrhagic cystitis after allogeneic bone marrow transplantation.

PubMed

Savva-Bordalo, J; Pinho Vaz, C; Sousa, M; Branca, R; Campilho, F; Resende, R; Baldaque, I; Camacho, O; Campos, A

2012-08-01

Late-onset hemorrhagic cystitis (HC) after allogeneic hematopoietic stem cell transplantation (HSCT) has been associated with BK virus (BKV). Antiviral drugs are of limited efficacy and the optimal treatment for HC has not yet been established. Hyperbaric oxygen (HBO) may benefit these patients. We, therefore, retrospectively evaluated the effectiveness of HBO therapy in 16 patients with HC after allogeneic HSCT. All 16 patients had macroscopic hematuria and BKV infection. Patients received 100% oxygen in a hyperbaric chamber at 2.1 atmospheres for 90 min, 5 days per week, with a median 13 treatments (range, 4-84). Fifteen patients (94%) showed complete resolution of hematuria. Median urinary DNA BKV titers declined after HBO (P<0.05). Patients started on HBO earlier after diagnosis of HC responded sooner (P<0.05). HBO was generally well tolerated and proved to be a reliable option for this difficult to manage condition.

Prony series spectra of structural relaxation in N-BK7 for finite element modeling.

PubMed

Koontz, Erick; Blouin, Vincent; Wachtel, Peter; Musgraves, J David; Richardson, Kathleen

2012-12-20

Structural relaxation behavior of N-BK7 glass was characterized at temperatures 20 °C above and below T(12) for this glass, using a thermo mechanical analyzer (TMA). T(12) is a characteristic temperature corresponding to a viscosity of 10(12) Pa·s. The glass was subject to quick temperature down-jumps preceded and followed by long isothermal holds. The exponential-like decay of the sample height was recorded and fitted using a unique Prony series method. The result of his method was a plot of the fit parameters revealing the presence of four distinct peaks or distributions of relaxation times. The number of relaxation times decreased as final test temperature was increased. The relaxation times did not shift significantly with changing temperature; however, the Prony weight terms varied essentially linearly with temperature. It was also found that the structural relaxation behavior of the glass trended toward single exponential behavior at temperatures above the testing range. The result of the analysis was a temperature-dependent Prony series model that can be used in finite element modeling of glass behavior in processes such as precision glass molding (PGM).

Bladder carcinoma in a transplant recipient: evidence to implicate the BK human polyomavirus as a causal transforming agent.

PubMed

Geetha, Duvuru; Tong, Betty C; Racusen, Lorraine; Markowitz, Jay S; Westra, William H

2002-06-27

The BK polyomavirus (BKV) infects most of the human population, but clinically relevant infections are mostly limited to individuals who are immunosuppressed. In transplant recipients, BKV has been associated with ureteral stenosis, interstitial nephritis, and hemorrhagic cystitis. The role of BKV in the development of human tumors is intriguing but uncertain. BKV has been identified in various tumor types including urothelial carcinoma, but the ubiquitous presence of BKV as a latent infection has confounded efforts to validate any causal role in cancer development. We report the case of a simultaneous pancreas and kidney transplant recipient who developed BKV interstitial nephritis and carcinoma of the bladder with widespread metastases. High level expression of BKV large T antigen in the primary and metastatic carcinoma, but not in the nonneoplastic urothelium, implicates BKV as an etiologic agent in the development of this tumor.

Cellular immunotherapy for patients with reactivation of JC and BK polyomaviruses after transplantation.

PubMed

Mani, Jiju; Jin, Nan; Schmitt, Michael

2014-10-01

Immunosuppression of patients after hematopoietic stem cell or kidney transplantation potentially leads to reactivation of JC and BK polyomaviruses. In hematopoietic stem cell transplantation, the reactivation rate of BKV can be up to 60%, resulting in severe complications of the urogenital tract, particularly hemorrhagic cystitis and renal dysfunction. After kidney transplantation, BKV reactivation can cause a loss of the graft. JCV can cause progressive multifocal leukoencephalopathy, a lethal disease. Adoptive transfer of donor-derived polyomavirus-specific T cells is an attractive and promising treatment that restores virus-specific cellular immunity. Pioneering work in the early 1990s on the reconstitution of cellular immunity against cytomegalovirus and recent development in the field of monitoring and isolation of antigen-specific T cells paved the way toward a personalized T-cell therapy. Multimer technology and magnetic beads are available to produce untouched T cells in a single-step, good manufacturing practice-compliant procedure. Another exciting aspect of T-cell therapy against polyomaviruses is the fact that both JCV and BKV can be targeted simultaneously because of their high sequence homology. Finally, "designer T cells" can be redirected to recognize polyomavirus antigens with high-affinity T-cell receptors. This review summarizes the state-of-the art technologies and gives an outlook of future developments in the field. Copyright © 2014 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Orientations and Proximities of the Extracellular Ends of Transmembrane Helices S0 and S4 in Open and Closed BK Potassium Channels

PubMed Central

Wu, Roland S.; Chudasama, Neelesh; Zakharov, Sergey I.; Karlin, Arthur; Marx, Steven O.

2013-01-01

The large-conductance potassium channel (BK) α subunit contains a transmembrane (TM) helix S0 preceding the canonical TM helices S1 through S6. S0 lies between S4 and the TM2 helix of the regulatory β1 subunit. Pairs of Cys were substituted in the first helical turns in the membrane of BK α S0 and S4 and in β1 TM2. One such pair, W22C in S0 and W203C in S4, was 95% crosslinked endogenously. Under voltage-clamp conditions in outside-out patches, this crosslink was reduced by DTT and reoxidized by a membrane-impermeant bis-quaternary ammonium derivative of diamide. The rate constants for this reoxidation were not significantly different in the open and closed states of the channel. Thus, these two residues are approximately equally close in the two states. In addition, 90% crosslinking of a second pair, R20C in S0 and W203C in S4, had no effect on the V50 for opening. Taken together, these findings indicate that separation between residues at the extracellular ends of S0 and S4 is not required for voltage-sensor activation. On the contrary, even though W22C and W203C were equally likely to form a disulfide in the activated and deactivated states, relative immobilization by crosslinking of these two residues favored the activated state. Furthermore, the efficiency of recrosslinking of W22C and W203C on the cell surface was greater in the presence of the β1 subunit than in its absence, consistent with β1 acting through S0 to stabilize its immobilization relative to α S4. PMID:23472181

An Association between BK Virus Replication in Bone Marrow and Cytopenia in Kidney-Transplant Recipients

PubMed Central

Pambrun, Emilie; Mengelle, Catherine; Fillola, Geneviève; Laharrague, Patrick; Esposito, Laure; Cardeau-Desangles, Isabelle; Del Bello, Arnaud; Izopet, Jacques; Rostaing, Lionel; Kamar, Nassim

2014-01-01

The human polyomavirus BK (BKV) is associated with severe complications, such as ureteric stenosis and polyomavirus-associated nephropathy (PVAN), which often occur in kidney-transplant patients. However, it is unknown if BKV can replicate within bone marrow. The aim of this study was to search for BKV replication within the bone marrow of kidney-transplant patients presenting with a hematological disorder. Seventy-two kidney-transplant patients underwent bone-marrow aspiration for cytopenia. At least one virus was detected in the bone marrow of 25/72 patients (35%), that is, parvovirus B19 alone (n = 8), parvovirus plus Epstein-Barr virus (EBV) (n = 3), cytomegalovirus (n = 4), EBV (n = 2), BKV alone (n = 7), and BKV plus EBV (n = 1). Three of the eight patients who had BKV replication within the bone marrow had no detectable BKV replication in the blood. Neutropenia was observed in all patients with BKV replication in the bone marrow, and blockade of granulocyte maturation was observed. Hematological disorders disappeared in all patients after doses of immunosuppressants were reduced. In conclusion, an association between BKV replication in bone marrow and hematological disorders, especially neutropenia, was observed. Further studies are needed to confirm these findings. PMID:24868448

Epidemiologic Study and Genotyping of BK Virus in Renal Transplant Recipients.

PubMed

Cobos, M; Aquilia, L; Garay, E; Ochiuzzi, S; Alvarez, S; Flores, D; Raimondi, C

2018-03-01

BK virus (BKV) infection occurs during childhood and remains latent in the urinary tract. The virus is reactivated in immunosuppressed patients, particularly in those with cellular immunity deficiency, allowing its detection in urine and blood. Nephropathy caused by the virus in renal transplantation recipients may lead to graft failure. The purpose of this study is to know the prevalence of BKV variables in renal transplantation recipients and to evaluate their clinical evolution through molecular methods of "in house" development. Urine and peripheral blood samples from 66 renal transplantation recipients from the province of Buenos Aires, Argentina, were systematically analyzed every 3 months as well as when there was graft dysfunction. Renal biopsies, which were included in the BKV detection study, were performed on those patients with graft dysfunction. Genotyping of 24 BKVs was performed, and the following distribution was found: 21 (87.5%) belonged to subtype I, 3 (12.5%) to subtype II. BKV belonging to subtypes III or IV were not found. As regards subtype I subgroups, the following were identified: 1 (4.76%) from Ia, 10 (47.61%) from Ib1 and 10 (47.61%) from Ib2. Presence of subgroup Ic was not shown. Viremia presented in 33.33% of cases, whereas 75% corresponded to subgroup Ib 1. Genotype Ib1 is prevailing in Southeast Asia, while Ib2 is prominent in Europe. Although an important proportion of the inhabitants of the province of Buenos Aires are European descendants, the prevailing genotype is Ib1, the Asian type. Genotyping might be related to the evolution of the disease in the recipient. Copyright © 2017 Elsevier Inc. All rights reserved.

Functional Reorganization of Promyelocytic Leukemia Nuclear Bodies during BK Virus Infection

PubMed Central

Jiang, Mengxi; Entezami, Pouya; Gamez, Monica; Stamminger, Thomas; Imperiale, Michael J.

2011-01-01

BK virus (BKV) is the causative agent for polyomavirus-associated nephropathy, a severe disease found in renal transplant patients due to reactivation of a persistent BKV infection. BKV replication relies on the interactions of BKV with many nuclear components, and subnuclear structures such as promyelocytic leukemia nuclear bodies (PML-NBs) are known to play regulatory roles during a number of DNA virus infections. In this study, we investigated the relationship between PML-NBs and BKV during infection of primary human renal proximal tubule epithelial (RPTE) cells. While the levels of the major PML-NB protein components remained unchanged, BKV infection of RPTE cells resulted in dramatic alterations in both the number and the size of PML-NBs. Furthermore, two normally constitutive components of PML-NBs, Sp100 and hDaxx, became dispersed from PML-NBs. To define the viral factors responsible for this reorganization, we examined the cellular localization of the BKV large tumor antigen (TAg) and viral DNA. TAg colocalized with PML-NBs during early infection, while a number of BKV chromosomes were adjacent to PML-NBs during late infection. We demonstrated that TAg alone was not sufficient to reorganize PML-NBs and that active viral DNA replication is required. Knockdown of PML protein did not dramatically affect BKV growth in culture. BKV infection, however, was able to rescue the growth of an ICP0-null herpes simplex virus 1 mutant whose growth defect was partially due to its inability to disrupt PML-NBs. We hypothesize that the antiviral functions of PML-NBs are inactivated through reorganization during normal BKV infection. PMID:21304169

Analysis of decay chains of superheavy nuclei produced in the 249Bk+48Ca and 243Am+48Ca reactions

NASA Astrophysics Data System (ADS)

Zlokazov, V. B.; Utyonkov, V. K.

2017-07-01

The analysis of decay chains starting at superheavy nuclei 293Ts and 289Mc is presented. The spectroscopic properties of nuclei identified during the experiments using the 249Bk+48Ca and 243Am+48Ca reactions studied at the gas-filled separators DGFRS, TASCA and BGS are considered. We present the analysis of decay data using widely adopted statistical methods and applying them to the short decay chains of parent odd-Z nuclei. We find out that the recently suggested method of analyzing decay chains by Forsberg et al may lead to questionable conclusions when applied for the analysis of radioactive decays. Our discussion demonstrates reasonable congruence of α-particle energies and decay times of nuclei assigned to isotopes 289Mc, 285Nh and 281Rg observed in both reactions.

De Novo Collapsing Glomerulopathy in Renal Allograft in Association with BK Virus Nephropathy in a Child and Stabilization of Renal Function by Elimination of Viremia.

PubMed

Gera, D N; Shah, M K; Ghodela, V A; Kute, V B; Trivedi, H L

2017-01-01

Well-recognized association between HIV 1 infection and collapsing glomerulopathy (CG) raises the possibility that intrarenal infection by other viruses may also contribute to the development of this lesion in native or post-transplant kidneys. There is evidence in literature about association of these lesions with cytomegalovirus, Epstein-Barr virus, hepatitis C virus, and parvovirus B19 infections. Here, we present a case report of post-transplant BK virus nephropathy in a male child who was found to have CG in subsequent biopsy 2 months later. His renal function and proteinuria were stabilized on elimination of viremia.

Transcriptome Analysis of the Role of GlnD/GlnBK in Nitrogen Stress Adaptation by Sinorhizobium meliloti Rm1021

PubMed Central

Yurgel, Svetlana N.; Rice, Jennifer; Kahn, Michael L.

2013-01-01

Transcriptional changes in the nitrogen stress response (NSR) of wild type S. meliloti Rm1021, and isogenic strains missing both PII proteins, GlnB and GlnK, or carrying a ΔglnD-sm2 mutation were analyzed using whole-genome microarrays. This approach allowed us to identify a number of new genes involved in the NSR and showed that the response of these bacteria to nitrogen stress overlaps with other stress responses, including induction of the fixK2 transcriptional activator and genes that are part of the phosphate stress response. Our data also show that GlnD and GlnBK proteins may regulate many genes that are not part of the NSR. Analysis of transcriptome profiles of the Rm1021 ΔglnD-sm2 strain allowed us to identify several genes that appear to be regulated by GlnD without the participation of the PII proteins. PMID:23516427

Levofloxacin for the treatment of severe refractory BK virus-associated hemorrhagic cystitis in hematopoietic stem cell transplantation recipients: A report of three cases.

PubMed

Toptas, Tayfur; Kaygusuz-Atagunduz, Isik; Kani, Haluk Tarik; Adiguzel, Cafer; Firatli-Tuglular, Tulin

2014-10-01

BK-virus (BKV) is an important etiological agent for late-onset hemorrhagic cystitis (HC) in patients undergoing hematopoietic stem cell transplantation. Late-onset HC causes significant morbidity among these patients. Therapeutic approaches remain predominantly symptomatic. Several treatment options have been used with variable success rates. Cidofovir has the highest specificity against BKV; however, its lack of availability in the majority of countries, high costs and potential nephrotoxic effects limit its use. The present study reports three cases of severe and prolonged BKV-associated HC (BKHC). HC was resolved in all three of the patients using oral levofloxacin. Thus, levofloxacin may be an effective treatment modality for achieving complete clinical and molecular response in patients with refractory, severe BKHC.

Frequency and subtype of BK virus infection in Iranian patients infected with HIV.

PubMed

Akhgari, Shahla; Mohraz, Minoo; Azadmanesh, Kayhan; Vahabpour, Rouhollah; Kazemimanesh, Monireh; Aghakhani, Arezoo; Jozpanahi, Manizheh; Banifazl, Mohammad; Bavand, Anahita; Ramezani, Amitis

2016-02-01

Human polyomavirus BK virus (BKV) is a double-stranded DNA virus that infects approximately 90 % of the general population as a subclinical or mild infection. In immunosuppressed patients, such as HIV cases, BKV may be reactivated resulting hemorrhagic cystitis and tubulointerstitial nephritis. However, there are limited studies on prevalence and molecular epidemiology of BKV in Iran. We therefore aimed to evaluate the prevalence and subtypes of BKV in Iranian HIV patients. A total of 99 patients with HIV infection were enrolled in the study. Presence of BKV DNA in plasma was evaluated by nested PCR. PCR products were sequenced directly, and phylogenetic analysis was performed. BKV DNA was detected in 8.08 % of HIV patients. BKV viremia presented in 4 out of 25 patients (16 %) not receiving antiretroviral therapy in comparison with 4 out 74 of HAART-treated patients (5.4 %) (P = 0.023). In patients with CD4 counts ≥200 cells/mm(3), viremia was found more commonly (7/80 = 8.8 %) than in those with lower counts (1/19 = 5.2 %) (not significant). All sequenced BKV isolates belonged to subtype Ib-2. Our findings indicated that the prevalence of BKV viremia is relatively prevalent in patients with HIV infection and significantly higher in naïve than HAART-treated cases. Therefore, HAART can eliminate BKV infection from plasma and reduce viremia although the actual implication of BKV viremia in HIV patients is not clear.

Choreito formula for BK virus-associated hemorrhagic cystitis after allogeneic hematopoietic stem cell transplantation.

PubMed

Kawashima, Nozomu; Ito, Yoshinori; Sekiya, Yuko; Narita, Atsushi; Okuno, Yusuke; Muramatsu, Hideki; Irie, Masahiro; Hama, Asahito; Takahashi, Yoshiyuki; Kojima, Seiji

2015-02-01

Therapy for BK virus (BKV)-associated hemorrhagic cystitis (BKV-HC) is limited after hematopoietic stem cell transplantation (HSCT). We examined whether choreito, a formula from Japanese traditional Kampo medicine, is effective for treating BKV-HC. Among children who underwent allogeneic HSCT between October 2006 and March 2014, 14 were diagnosed with BKV-HC (median, 36 days; range, 14 to 330 days) after HSCT, and 6 consecutive children received pharmaceutical-grade choreito extract granules. The hematuria grade before treatment was significantly higher in the choreito group than in the nonchoreito group (P = .018). The duration from therapy to complete resolution was significantly shorter in the choreito group (median, 9 days; range, 4 to 17 days) than in the nonchoreito group (median, 17 days; range, 15 to 66 days; P = .037). In 11 children with macroscopic hematuria, the duration from treatment to resolution of macroscopic hematuria was significantly shorter in the choreito group than in the nonchoreito group (median, 2 days versus 11 days; P = .0043). The BKV load in urine was significantly decreased 1 month after choreito administration. No adverse effects related to choreito administration were observed. Choreito may be a safe and considerably promising therapy for the hemostasis of BKV-HC after HSCT. Copyright © 2015 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

Levofloxacin for the treatment of severe refractory BK virus-associated hemorrhagic cystitis in hematopoietic stem cell transplantation recipients: A report of three cases

PubMed Central

TOPTAS, TAYFUR; KAYGUSUZ-ATAGUNDUZ, ISIK; KANI, HALUK TARIK; ADIGUZEL, CAFER; FIRATLI-TUGLULAR, TULIN

2014-01-01

BK-virus (BKV) is an important etiological agent for late-onset hemorrhagic cystitis (HC) in patients undergoing hematopoietic stem cell transplantation. Late-onset HC causes significant morbidity among these patients. Therapeutic approaches remain predominantly symptomatic. Several treatment options have been used with variable success rates. Cidofovir has the highest specificity against BKV; however, its lack of availability in the majority of countries, high costs and potential nephrotoxic effects limit its use. The present study reports three cases of severe and prolonged BKV-associated HC (BKHC). HC was resolved in all three of the patients using oral levofloxacin. Thus, levofloxacin may be an effective treatment modality for achieving complete clinical and molecular response in patients with refractory, severe BKHC. PMID:25202408

Transformation of primary human embryonic kidney cells to anchorage independence by a combination of BK virus DNA and the Harvey-ras oncogene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pater, A.; Pater, M.M.

Primary human embryonic kidney (HEK) cells were transformed by a focus assay with BK virus (BKV) DNA molecularly cloned at its unique EcoRI site. Both viral DNA sequences and viral tumor antigens were present and expressed in all the foci that the authors examined. However, cells isolated from foci were incapable of growth in soft agar. They then examined the transformation of HEK cells after their transfection with a combination of BKV DNA and either the normal or the activated form of the human Ha-ras oncogene (EJ c-Ha-ras-1). Only the cells transfected with a combination of BKV DNA and themore » activated form of Ha-ras DNAs were present in the transformed colonies. BKV tumor antigens and the Ha-ras p21 protein were also expressed.« less

Integrative Approach for Computationally Inferring Interactions between the Alpha and Beta Subunits of the Calcium-Activated Potassium Channel (BK): a Docking Study

PubMed Central

González, Janneth; Gálvez, Angela; Morales, Ludis; Barreto, George E.; Capani, Francisco; Sierra, Omar; Torres, Yolima

2013-01-01

Three-dimensional models of the alpha- and beta-1 subunits of the calcium-activated potassium channel (BK) were predicted by threading modeling. A recursive approach comprising of sequence alignment and model building based on three templates was used to build these models, with the refinement of non-conserved regions carried out using threading techniques. The complex formed by the subunits was studied by means of docking techniques, using 3D models of the two subunits, and an approach based on rigid-body structures. Structural effects of the complex were analyzed with respect to hydrogen-bond interactions and binding-energy calculations. Potential interaction sites of the complex were determined by referencing a study of the difference accessible surface area (DASA) of the protein subunits in the complex. PMID:23492851

BK Polyomavirus-Specific 9mer CD8 T Cell Responses Correlate With Clearance of BK Viremia in Kidney Transplant Recipients: First Report From the Swiss Transplant Cohort Study.

PubMed

Leboeuf, C; Wilk, S; Achermann, R; Binet, I; Golshayan, D; Hadaya, K; Hirzel, C; Hoffmann, M; Huynh-Do, U; Koller, M T; Manuel, O; Mueller, N J; Mueller, T F; Schaub, S; van Delden, C; Weissbach, F H; Hirsch, H H

2017-10-01

BK polyomavirus (BKPyV) causes premature kidney transplant (KT) failure in 1-15% of patients. Because antivirals are lacking, most programs screen for BKPyV-viremia and, if positive, reduce immunosuppression. To evaluate the relationship of viremia and BKPyV-specific immunity, we examined prospectively cryopreserved plasma and peripheral blood mononuclear cells at the time of transplantation (T0) and at 6 mo (T6) and 12 mo (T12) after transplant from 28 viremic KT patients and 68 nonviremic controls matched for the transplantation period. BKPyV IgG seroprevalence was comparable between cases (89.3%) and controls (91.2%; p = 0.8635), but cases had lower antibody levels (p = 0.022) at T0. Antibody levels increased at T6 and T12 but were not correlated with viremia clearance. BKPyV-specific T cell responses to pools of overlapping 15mers (15mer peptide pool [15mP]) or immunodominant CD8 9mers (9mer peptide pool [9mP]) from the early viral gene region were not different between cases and controls at T0; however, clearance of viremia was associated with stronger 9mP responses at T6 (p = 0.042) and T12 (p = 0.048), whereas 15mP responses were not informative (T6 p = 0.359; T12 p = 0.856). BKPyV-specific T cells could be expanded in vitro from all patients after transplant, permitting identification of 78 immunodominant 9mer epitopes including 50 new ones across different HLA class I. Thus, 9mP-responses may be a novel marker of reconstituting CD8 T cell function that warrants further study as a complement of plasma BKPyV loads for guiding immunosuppression reduction. © 2017 The American Society of Transplantation and the American Society of Transplant Surgeons.

Production and investigation of thin films of metal actinides (Pu, Am, Cm, Bk, Cf)

NASA Astrophysics Data System (ADS)

Radchenko, V. M.; Ryabinin, M. A.; Stupin, V. A.

2010-03-01

Under limited availability of transplutonium metals some special techniques and methods of their production have been developed that combine the process of metal reduction from a chemical compound and preparation of a sample for examination. In this situation the evaporation and condensation of metal onto a substrate becomes the only possible technology. Thin film samples of metallic 244Cm, 248Cm and 249Bk were produced by thermal reduction of oxides with thorium followed by deposition of the metals in the form of thin layers on tantalum substrates. For the production of 249Cf metal in the form of a thin layer the method of thermal reduction of oxide with lanthanum was used. 238Pu and 239Pu samples in the form of films were prepared by direct high temperature evaporation and condensation of the metal onto a substrate. For the production of 241Am films a gram sample of plutonium-241 metal was used containing about 18 % of americium at the time of production. Thermal decomposition of Pt5Am intermetallics in vacuum was used to produce americium metal with about 80% yield. Resistivity of the metallic 249Cf film samples was found to decrease exponentially with increasing temperature. The 249Cf metal demonstrated a tendency to form preferably a DHCP structure with the sample mass increasing. An effect of high specific activity on the crystal structure of 238Pu nuclide thin layers was studied either.

Different risk factors related to adenovirus- or BK virus-associated hemorrhagic cystitis following allogeneic stem cell transplantation.

PubMed

Mori, Yasuo; Miyamoto, Toshihiro; Kato, Koji; Kamezaki, Kenjiro; Kuriyama, Takuro; Oku, Seido; Takenaka, Katsuto; Iwasaki, Hiromi; Harada, Naoki; Shiratsuchi, Motoaki; Abe, Yasunobu; Nagafuji, Koji; Teshima, Takanori; Akashi, Koichi

2012-03-01

Virus-associated hemorrhagic cystitis (HC) is a major cause of morbidity and mortality following allogeneic hematopoietic stem cell transplantation (HSCT). Although numerous studies have attempted to identify factors that predispose patients to viral HC, its causes remain controversial. We analyzed retrospectively the results of 266 allogeneic HSCTs to identify factors associated with HC. Of this group, 42 patients (15.8%) were diagnosed with viral HC, because of either adenovirus (ADV; n = 26; 9.8%) or BK virus (BKV; n = 16; 6.0%). ADV-HC was frequently associated with T cell purging, and was less common in patients with acute graft-versus-host-disease (GVHD). Conversely, BKV-HC was more frequently observed in patients with excessive immune reactions such as GVHD, preengraftment immune reaction, and hemophagocytic syndrome. These observations indicate that ADV- and BKV-HC may differ significantly in their risk factors and pathogenesis. Profound immune deficiency is more likely to be associated with ADV-HC, whereas immune hyperactivity might play a key role in BKV-HC. Copyright © 2012 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

Polyomavirus BK-specific CD8+ T cell responses in patients after allogeneic stem cell transplant.

PubMed

Schneidawind, Dominik; Schmitt, Anita; Wiesneth, Markus; Mertens, Thomas; Bunjes, Donald; Freund, Mathias; Schmitt, Michael

2010-06-01

Polyomavirus BK (BKV) is known as an important etiologic agent in the development of hemorrhagic cystitis (HC) after allogeneic stem cell transplant (SCT). To define T cell epitopes of the BKV proteins VP1 and sT, eight potential HLA-A2-binding peptides were synthesized based on computer algorithms. These peptides were co-incubated with CD8 + T cells from the peripheral blood (PB) of 25 healthy volunteers and seven patients suffering from HC after allogeneic SCT in a mixed-lymphocyte peptide culture (MLPC), which were subsequently screened by enzyme-linked immunospot (ELISPOT) assays and fluorescence-activated cell sorting (FACS) analysis. We found that CD8 + T cells from five of seven (71%) patients with HC presensitized with the BKV peptide VP1 p108 (LLMWEAVTV) specifically recognized T2 cells pulsed with VP1 p108. In contrast, only seven of 25 (28%) healthy volunteers had CD8 + T cells reactive with VP1 p108-pulsed T2 cells. The presence of VP1 p108-specific T cells could be confirmed by FACS analysis. The BKV peptide VP1 p108 seems to play an important role as an immunodominant peptide in the pathogenesis of HC in patients after allogeneic SCT, and might be a promising target for immunotherapies or even strategies to prevent the development of BKV-associated HC.

BK virus encephalopathy and sclerosing vasculopathy in a patient with hypohidrotic ectodermal dysplasia and immunodeficiency.

PubMed

Darbinyan, Armine; Major, Eugene O; Morgello, Susan; Holland, Steven; Ryschkewitsch, Caroline; Monaco, Maria Chiara; Naidich, Thomas P; Bederson, Joshua; Malaczynska, Joanna; Ye, Fei; Gordon, Ronald; Cunningham-Rundles, Charlotte; Fowkes, Mary; Tsankova, Nadejda M

2016-07-13

Human BK polyomavirus (BKV) is reactivated under conditions of immunosuppression leading most commonly to nephropathy or cystitis; its tropism for the brain is rare and poorly understood. We present a unique case of BKV-associated encephalopathy in a man with hypohidrotic ectodermal dysplasia and immunodeficiency (HED-ID) due to IKK-gamma (NEMO) mutation, who developed progressive neurological symptoms. Brain biopsy demonstrated polyomavirus infection of gray and white matter, with predominant involvement of cortex and distinct neuronal tropism, in addition to limited demyelination and oligodendroglial inclusions. Immunohistochemistry demonstrated polyoma T-antigen in neurons and glia, but expression of VP1 capsid protein only in glia. PCR analysis on both brain biopsy tissue and cerebrospinal fluid detected high levels of BKV DNA. Sequencing studies further identified novel BKV variant and disclosed unique rearrangements in the noncoding control region of the viral DNA (BKVN NCCR). Neuropathological analysis also demonstrated an unusual form of obliterative fibrosing vasculopathy in the subcortical white matter with abnormal lysosomal accumulations, possibly related to the patient's underlying ectodermal dysplasia. Our report provides the first neuropathological description of HED-ID due to NEMO mutation, and expands the diversity of neurological presentations of BKV infection in brain, underscoring the importance of its consideration in immunodeficient patients with unexplained encephalopathy. We also document novel BKVN NCCR rearrangements that may be associated with the unique neuronal tropism in this patient.

Cidofovir inhibits polyomavirus BK replication in human renal tubular cells downstream of viral early gene expression.

PubMed

Bernhoff, E; Gutteberg, T J; Sandvik, K; Hirsch, H H; Rinaldo, C H

2008-07-01

The human polyomavirus BK (BKV) causes nephropathy and hemorrhagic cystitis in kidney and bone marrow transplant patients, respectively. The anti-viral cidofovir (CDV) has been used in small case series but the effects on BKV replication are unclear, since polyomaviruses do not encode viral DNA polymerases. We investigated the effects of CDV on BKV(Dunlop) replication in primary human renal proximal tubule epithelial cells (RPTECs). CDV inhibited the generation of viral progeny in a dose-dependent manner yielding a 90% reduction at 40 microg/mL. Early steps such as receptor binding and entry seemed unaffected. Initial large T-antigen transcription and expression were also unaffected, but subsequent intra-cellular BKV DNA replication was reduced by >90%. Late viral mRNA and corresponding protein levels were also 90% reduced. In uninfected RPTECs, CDV 40 microg/mL reduced cellular DNA replication and metabolic activity by 7% and 11% in BrdU and WST-1 assays, respectively. BKV infection increased DNA replication to 142% and metabolic activity to 116%, respectively, which were reduced by CDV 40 microg/mL to levels of uninfected untreated RPTECs. Our results show that CDV inhibits BKV DNA replication downstream of large T-antigen expression and involves significant host cell toxicity. This should be considered in current treatment and drug development.

Comparative Evaluation of Three Nucleic Acid-Based Assays for BK Virus Quantification

PubMed Central

Descamps, Veronique; Martin, Elodie; Morel, Virginie; François, Catherine; Helle, François; Duverlie, Gilles; Castelain, Sandrine

2015-01-01

With the growing importance of BK virus (BKV), effective and efficient screening for BKV replication in plasma and urine samples is very important for monitoring renal transplant and hematopoietic stem cell transplant recipients, who are at increased risk of BKV-associated diseases. However, recent assays proposed by many manufacturers have not been tested, and the available tests have not been standardized. The aim of the present study was to evaluate and compare the performances of three commercially available kits, R-gene, GeneProof, and RealStar, on plasma and urine specimens from patients infected with various genotypes and to determine the correlations with the results from a reference laboratory. A qualitatively excellent global agreement (96.8%) was obtained. RealStar PCR tended to give a higher sensitivity, especially for subtype Ib1 samples. Comparison of 30 plasma samples and 53 urine samples showed a good agreement between the three assays, with Spearman's Rho correlation coefficient values falling between 0.92 and 0.98 (P < 0.001). Moreover, a perfect correlation was obtained for comparison of the assay performances with the AcroMetrix BKV panel (P < 0.001 for all comparisons). According to Bland-Altman analysis, more than 95% (240/249 comparisons) of sample comparisons were situated in the range of the mean ± 2 standard deviations (SD). The greatest variability between assays was observed for 10.2% of subtype Ib2 samples, with differences of >1 log10 copies/ml. In conclusion, this study demonstrated the reliable and comparable performances of the R-gene, GeneProof, and RealStar real-time PCR systems for quantification of BKV in urine and plasma samples. All three real-time PCR assays are appropriate for screening of BKV replication in patients. PMID:26424842

Fluoroquinolones inhibit human polyomavirus BK (BKV) replication in primary human kidney cells.

PubMed

Sharma, Biswa Nath; Li, Ruomei; Bernhoff, Eva; Gutteberg, Tore Jarl; Rinaldo, Christine Hanssen

2011-10-01

Reactivation of human polyomavirus BK (BKV) may cause polyomavirus-associated nephropathy or polyomavirus-associated hemorrhagic cystitis in renal- or bone marrow-transplant patients, respectively. Lack of treatment options has led to exploration of fluoroquinolones that inhibit topoisomerase II and IV in prokaryotes and possibly large T-antigen (LT-ag) helicase activity in polyomavirus. We characterized the effects of ofloxacin and levofloxacin on BKV replication in the natural host cells - primary human renal proximal tubular epithelial cells (RPTECs). Ofloxacin and levofloxacin inhibited BKV load in a dose-dependent manner yielding a ∼90% inhibition at 150 μg/ml. Ofloxacin at 150 μg/ml inhibited LT-ag mRNA and protein expression from 24h post infection (hpi). BKV genome replication was 77% reduced at 48 hpi and a similar reduction was found in VP1 and agnoprotein expression. At 72 hpi, the reduction in genome replication and protein expression was less pronounced. A dose-dependent cytostatic effect was noted. In infected cells, 150 μg/ml ofloxacin led to a 26% and 6% inhibition of cellular DNA replication and total metabolic activity, respectively while 150 μg/ml levofloxacin affected this slightly more, particularly in uninfected cells. Cell counting and xCELLigence results revealed that cell numbers were not reduced. In conclusion, ofloxacin and levofloxacin inhibit but do not eradicate BKV replication in RPTECs. At a concentration of ofloxacin giving ∼90% inhibition in BKV load, no significant cytotoxicity was observed. This concentration can be achieved in urine and possibly in the kidneys. Our results support a mechanism involving inhibition of LT-ag expression or functions but also suggest inhibition of cellular enzymes. Copyright © 2011 Elsevier B.V. All rights reserved.

Limited Variation in BK Virus T-Cell Epitopes Revealed by Next-Generation Sequencing

PubMed Central

Sahoo, Malaya K.; Tan, Susanna K.; Chen, Sharon F.; Kapusinszky, Beatrix; Concepcion, Katherine R.; Kjelson, Lynn; Mallempati, Kalyan; Farina, Heidi M.; Fernández-Viña, Marcelo; Tyan, Dolly; Grimm, Paul C.; Anderson, Matthew W.; Concepcion, Waldo

2015-01-01

BK virus (BKV) infection causing end-organ disease remains a formidable challenge to the hematopoietic cell transplant (HCT) and kidney transplant fields. As BKV-specific treatments are limited, immunologic-based therapies may be a promising and novel therapeutic option for transplant recipients with persistent BKV infection. Here, we describe a whole-genome, deep-sequencing methodology and bioinformatics pipeline that identify BKV variants across the genome and at BKV-specific HLA-A2-, HLA-B0702-, and HLA-B08-restricted CD8 T-cell epitopes. BKV whole genomes were amplified using long-range PCR with four inverse primer sets, and fragmentation libraries were sequenced on the Ion Torrent Personal Genome Machine (PGM). An error model and variant-calling algorithm were developed to accurately identify rare variants. A total of 65 samples from 18 pediatric HCT and kidney recipients with quantifiable BKV DNAemia underwent whole-genome sequencing. Limited genetic variation was observed. The median number of amino acid variants identified per sample was 8 (range, 2 to 37; interquartile range, 10), with the majority of variants (77%) detected at a frequency of <5%. When normalized for length, there was no statistical difference in the median number of variants across all genes. Similarly, the predominant virus population within samples harbored T-cell epitopes similar to the reference BKV strain that was matched for the BKV genotype. Despite the conservation of epitopes, low-level variants in T-cell epitopes were detected in 77.7% (14/18) of patients. Understanding epitope variation across the whole genome provides insight into the virus-immune interface and may help guide the development of protocols for novel immunologic-based therapies. PMID:26202116

Prevalence of Polyoma BK Virus (BKPyV), Epstein-Barr Virus (EBV) and Human Papilloma Virus (HPV) in Oropharyngeal Cancer.

PubMed

Polz-Gruszka, Dorota; Morshed, Kamal; Jarzyński, Adrian; Polz-Dacewicz, Małgorzata

2015-01-01

The aim of this study was to analyze the prevalence of BK virus, Human Papillomavirus and Epstein-Barr virus in oropharyngeal cancer, and to test our hypothesis that BKV/HPV/EBV co-infection plays a role in oropharyngeal squamous cell carcinoma. The correlation between viral infection, OSCC, anatomic location, pre-treatment staging, evidence of metastases to lymph nodes, and grading was also investigated. The examination samples were collected from 62 patients from paraffin tissue blocks. Males (90.3%) with, smoking (83.9%) and alcohol abuse (67.7%) problems prevailed in the studied group. G2 histological type was recognized in 80.6% cases. T4 (77.4%) and N2 (56.5%) traits occurred in the majority of patients. No cases of metastasis were observed (M0 100%). HPV - 24.2%, EBV - 27.4% and BKV 17.7% were detected in the studied samples. We observed co-infection EBV/BKV in 8% of cases, HPV/BKV in 4.8%, and HPV/EBV in 9% cases. Only in two cases co-infection of all three viruses was found.

BK virus (BKV) quantification in urine samples of bone marrow transplanted patients is helpful for diagnosis of hemorrhagic cystitis, although wide individual variations exist.

PubMed

Priftakis, Peter; Bogdanovic, Gordana; Kokhaei, Parviz; Mellstedt, Håkan; Dalianis, Tina

2003-01-01

Hemorrhagic cystitis (HC) in allogeneic bone marrow transplanted (BMT) patients is associated with BK virus (BKV) reactivation manifested as BK viruria. However, since 77-90% of all adult BMT patients excrete BKV, viral reactivation alone cannot be responsible for HC. Recently, a significant overrepresentation of C-->G mutations in the Sp1 binding site in the non-coding control region (NCCR) of BKV was shown to be present in HC patients and absent in non-HC patients. We aimed to investigate if this mutation resulted in excessive BKV excretion in HC patients. A Real-Time PCR was developed and used to quantify BKV in urine samples from 21 patients with HC, with and without the mutations, as well as from patients without HC. Quantification of BKV was successful in 18 of 21 urine patients (six with and six without C-->G mutations) and six patients without HC. A mean of 3.0 x 10(6) BKV copies/microl was detected in urine samples of HC patients with C-->G mutations, compared to a mean of 1.5 x 10(6) BKV copies/microl in HC patients without C-->G mutations and a mean of 1.0 x 10(6) BKV copies/microl in patients without HC. The obtained differences were however not statistically significant, due to one individual non-HC patient with an extremely high BKV copy number. Nevertheless, while 50% of the samples in the HC groups expressed 1 x 10(6) copies/microl or more, only one of the samples in the non-HC group contained a virus quantity higher than 5 x 10(5) copies. Although we could not confirm that the C-->G mutations in the Sp1 site of BKV were responsible for an increased viral load in patients with HC, our data suggest that levels of BKV above 10(4) copies/microl may indicate a risk for HC.

Commercially available immunoglobulins contain virus neutralizing antibodies against all major genotypes of polyomavirus BK.

PubMed

Randhawa, P; Pastrana, D V; Zeng, G; Huang, Y; Shapiro, R; Sood, P; Puttarajappa, C; Berger, M; Hariharan, S; Buck, C B

2015-04-01

Neutralizing antibodies (NAbs) form the basis of immunotherapeutic strategies against many important human viral infections. Accordingly, we studied the prevalence, titer, genotype-specificity, and mechanism of action of anti-polyomavirus BK (BKV) NAbs in commercially available human immune globulin (IG) preparations designed for intravenous (IV) use. Pseudovirions (PsV) of genotypes Ia, Ib2, Ic, II, III, and IV were generated by co-transfecting a reporter plasmid encoding luciferase and expression plasmids containing synthetic codon-modified VP1, VP2, and VP3 capsid protein genes into 293TT cells. NAbs were measured using luminometry. All IG preparations neutralized all BKV genotypes, with mean EC50 titers as high as 254 899 for genotype Ia and 6,666 for genotype IV. Neutralizing titers against genotypes II and III were higher than expected, adding to growing evidence that infections with these genotypes are more common than currently appreciated. Batch to batch variation in different lots of IG was within the limits of experimental error. Antibody mediated virus neutralizing was dose dependent, modestly enhanced by complement, genotype-specific, and achieved without effect on viral aggregation, capsid morphology, elution, or host cell release. IG contains potent NAbs capable of neutralizing all major BKV genotypes. Clinical trials based on sound pharmacokinetic principles are needed to explore prophylactic and therapeutic applications of these anti-viral effects, until effective small molecule inhibitors of BKV replication can be developed. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.

Analysis of real-time mixture cytotoxicity data following repeated exposure using BK/TD models.

PubMed

Teng, S; Tebby, C; Barcellini-Couget, S; De Sousa, G; Brochot, C; Rahmani, R; Pery, A R R

2016-08-15

Cosmetic products generally consist of multiple ingredients. Thus, cosmetic risk assessment has to deal with mixture toxicity on a long-term scale which means it has to be assessed in the context of repeated exposure. Given that animal testing has been banned for cosmetics risk assessment, in vitro assays allowing long-term repeated exposure and adapted for in vitro - in vivo extrapolation need to be developed. However, most in vitro tests only assess short-term effects and consider static endpoints which hinder extrapolation to realistic human exposure scenarios where concentration in target organs is varies over time. Thanks to impedance metrics, real-time cell viability monitoring for repeated exposure has become possible. We recently constructed biokinetic/toxicodynamic models (BK/TD) to analyze such data (Teng et al., 2015) for three hepatotoxic cosmetic ingredients: coumarin, isoeugenol and benzophenone-2. In the present study, we aim to apply these models to analyze the dynamics of mixture impedance data using the concepts of concentration addition and independent action. Metabolic interactions between the mixture components were investigated, characterized and implemented in the models, as they impacted the actual cellular exposure. Indeed, cellular metabolism following mixture exposure induced a quick disappearance of the compounds from the exposure system. We showed that isoeugenol substantially decreased the metabolism of benzophenone-2, reducing the disappearance of this compound and enhancing its in vitro toxicity. Apart from this metabolic interaction, no mixtures showed any interaction, and all binary mixtures were successfully modeled by at least one model based on exposure to the individual compounds. Copyright © 2016 Elsevier Inc. All rights reserved.

Analytical characterization of three cathinone derivatives, 4-MPD, 4F-PHP and bk-EPDP, purchased as bulk powder from online vendors.

PubMed

Apirakkan, Orapan; Frinculescu, Anca; Shine, Trevor; Parkin, Mark C; Cilibrizzi, Agostino; Frascione, Nunzianda; Abbate, Vincenzo

2018-02-01

Novel emerging drugs of abuse, also referred as new psychoactive substances, constitute an ever-changing mixture of chemical compounds designed to circumvent legislative controls by means of chemical modifications of previously banned recreational drugs. One such class, synthetic cathinones, namely β-keto derivatives of amphetamines, has been largely abused over the past decade. A number of new synthetic cathinones are detected each year, either in bulk powders/crystals or in biological matrices. It is therefore important to continuously monitor the supply of new synthetic derivatives and promptly report them. By using complementary analytical techniques (i.e. one- and two-dimensional NMR, FT-IR, GC-MS, HRMS and HPLC-UV), this study investigates the detection, identification and full characterization of 1-(4-methylphenyl)-2-(methylamino)pentanone (4-methylpentedrone, 4-MPD), 1-(4-fluorophenyl)-2-(pyrrolidin-1-yl)hexanone (4F-PHP) and 1-(1,3-benzodioxol-5-yl)-2-(ethylamino)-1-pentanone (bk-EPDP), three emerging cathinone derivatives. Copyright © 2017 John Wiley & Sons, Ltd.

Low-dose cidofovir treatment of BK virus-associated hemorrhagic cystitis in recipients of hematopoietic stem cell transplant.

PubMed

Savona, M R; Newton, D; Frame, D; Levine, J E; Mineishi, S; Kaul, D R

2007-06-01

In recipients of hematopoietic stem cell transplants (HSCTs), BK virus (BKV) has been associated with late-onset hemorrhagic cystitis (HC). In our institution, HSCT recipients with BKV-associated HC are treated with 1 mg/kg of cidofovir weekly. We identified HSCT recipients with BKV-associated HC, treated with weekly cidofovir. Microbiological response was defined as at least a one log reduction in urinary BKV viral load; clinical response was defined as improvement in symptoms and stability or reduction in the grade of cystitis. Nineteen allogeneic HSCT patients received a mean of 4.5 weekly doses of cidofovir. HC occurred at a mean of 68.7 days after transplant. A clinical response was detected in 16/19 (84%) patients, and 9/19 (47%) had a measurable microbiological response (8/10 nonresponders had a BKV viral load above the upper limit of the assay before treatment). Fourteen out of nineteen (74%) patients had no significant increase in serum creatinine. Five patients with renal dysfunction resolved after completion of the therapy and removal of other nephrotoxic agents. We conclude that weekly low-dose cidofovir appears to be a safe treatment option for BKV-associated HC. Although the efficacy of low-dose cidofovir is not proven, a prospective trial is warranted.

Antiviral effects of artesunate on polyomavirus BK replication in primary human kidney cells.

PubMed

Sharma, Biswa Nath; Marschall, Manfred; Henriksen, Stian; Rinaldo, Christine Hanssen

2014-01-01

Polyomavirus BK (BKV) causes polyomavirus-associated nephropathy (PyVAN) and hemorrhagic cystitis (PyVHC) in renal and bone marrow transplant patients, respectively. Antiviral drugs with targeted activity against BKV are lacking. Since the antimalarial drug artesunate was recently demonstrated to have antiviral activity, the possible effects of artesunate on BKV replication in human primary renal proximal tubular epithelial cells (RPTECs), the host cells in PyVAN, were explored. At 2 h postinfection (hpi), RPTECs were treated with artesunate at concentrations ranging from 0.3 to 80 μM. After one viral replication cycle (approximately 72 hpi), the loads of extracellular BKV DNA, reflecting viral progeny production, were reduced in a concentration-dependent manner. Artesunate at 10 μM reduced the extracellular BKV load by 65%; early large T antigen mRNA and protein expression by 30% and 75%, respectively; DNA replication by 73%; and late VP1 mRNA and protein expression by 47% and 64%, respectively. Importantly, the proliferation of RPTECs was also inhibited in a concentration-dependent manner. At 72 hpi, artesunate at 10 μM reduced cellular DNA replication by 68% and total metabolic activity by 47%. Cell impedance and lactate dehydrogenase measurements indicated a cytostatic but not a cytotoxic mechanism. Flow cytometry and 5-ethynyl-2'-deoxyuridine incorporation revealed a decreased number of cells in S phase and suggested cell cycle arrest in G0 or G2 phase. Both the antiproliferative and antiviral effects of artesunate at 10 μM were reversible. Thus, artesunate inhibits BKV replication in RPTECs in a concentration-dependent manner by inhibiting BKV gene expression and genome replication. The antiviral mechanism appears to be closely connected to cytostatic effects on the host cell, underscoring the dependence of BKV on host cell proliferative functions.

Antiviral Effects of Artesunate on Polyomavirus BK Replication in Primary Human Kidney Cells

PubMed Central

Sharma, Biswa Nath; Marschall, Manfred; Henriksen, Stian

2014-01-01

Polyomavirus BK (BKV) causes polyomavirus-associated nephropathy (PyVAN) and hemorrhagic cystitis (PyVHC) in renal and bone marrow transplant patients, respectively. Antiviral drugs with targeted activity against BKV are lacking. Since the antimalarial drug artesunate was recently demonstrated to have antiviral activity, the possible effects of artesunate on BKV replication in human primary renal proximal tubular epithelial cells (RPTECs), the host cells in PyVAN, were explored. At 2 h postinfection (hpi), RPTECs were treated with artesunate at concentrations ranging from 0.3 to 80 μM. After one viral replication cycle (approximately 72 hpi), the loads of extracellular BKV DNA, reflecting viral progeny production, were reduced in a concentration-dependent manner. Artesunate at 10 μM reduced the extracellular BKV load by 65%; early large T antigen mRNA and protein expression by 30% and 75%, respectively; DNA replication by 73%; and late VP1 mRNA and protein expression by 47% and 64%, respectively. Importantly, the proliferation of RPTECs was also inhibited in a concentration-dependent manner. At 72 hpi, artesunate at 10 μM reduced cellular DNA replication by 68% and total metabolic activity by 47%. Cell impedance and lactate dehydrogenase measurements indicated a cytostatic but not a cytotoxic mechanism. Flow cytometry and 5-ethynyl-2′-deoxyuridine incorporation revealed a decreased number of cells in S phase and suggested cell cycle arrest in G0 or G2 phase. Both the antiproliferative and antiviral effects of artesunate at 10 μM were reversible. Thus, artesunate inhibits BKV replication in RPTECs in a concentration-dependent manner by inhibiting BKV gene expression and genome replication. The antiviral mechanism appears to be closely connected to cytostatic effects on the host cell, underscoring the dependence of BKV on host cell proliferative functions. PMID:24145549

Solubility of NaCl in water and its melting point by molecular dynamics in the slab geometry and a new BK3-compatible force field

NASA Astrophysics Data System (ADS)

Kolafa, Jiří

2016-11-01

Saturated concentration of rock salt in water is determined by a simulation of brine in contact with a crystal in the slab geometry. The NaCl crystals are rotated to expose facets with higher Miller indices than [001] to brine. The rock salt melting point is obtained by both the standard and adiabatic simulations in the slab geometry with attention paid to finite size effects as well as to a possible influence of facets with higher Miller indices and applied stress. Two force fields are used, the Lennard-Jones-based model by Young and Cheatham with SPC/E water and the Kiss and Baranyai polarizable model with BK3 water. The latter model is refitted to thermomechanical properties of crystal NaCl leading to better values of solubility and the melting point.

Solubility of NaCl in water and its melting point by molecular dynamics in the slab geometry and a new BK3-compatible force field.

PubMed

Kolafa, Jiří

2016-11-28

Saturated concentration of rock salt in water is determined by a simulation of brine in contact with a crystal in the slab geometry. The NaCl crystals are rotated to expose facets with higher Miller indices than [001] to brine. The rock salt melting point is obtained by both the standard and adiabatic simulations in the slab geometry with attention paid to finite size effects as well as to a possible influence of facets with higher Miller indices and applied stress. Two force fields are used, the Lennard-Jones-based model by Young and Cheatham with SPC/E water and the Kiss and Baranyai polarizable model with BK3 water. The latter model is refitted to thermomechanical properties of crystal NaCl leading to better values of solubility and the melting point.

Phylogenetic reconstruction and polymorphism analysis of BK virus VP2 gene isolated from renal transplant recipients in China

PubMed Central

WANG, ZHANG-YANG; HONG, WEI-LONG; ZHU, ZHE-HUI; CHEN, YUN-HAO; YE, WEN-LE; CHU, GUANG-YU; LI, JIA-LIN; CHEN, BI-CHENG; XIA, PENG

2015-01-01

BK polyomavirus (BKV) is important pathogen for kidney transplant recipients, as it is frequently re-activated, leading to nephropathy. The aim of this study was to investigate the phylogenetic reconstruction and polymorphism of the VP2 gene in BKV isolated from Chinese kidney transplant recipients. Phylogenetic analysis was carried out in the VP2 region from 135 BKV-positive samples and 28 reference strains retrieved from GenBank. The unweighted pair-group method with arithmetic mean (UPGMA) grouped all strains into subtypes, but failed to subdivide strains into subgroups. Among the plasma and urine samples, all plasma (23/23) and 82 urine samples (82/95) were identified to contain subtype I; the other 10 urine samples contained subtype IV. A 86-bp fragment was identified as a highly conserved sequence. Following alignment with 36 published BKV sequences from China, 92 sites of polymorphism were identified, including 11 single nucleotide polymorphisms (SNPs) prevalent in Chinese individuals and 30 SNPs that were specific to the two predominant subtypes I and IV. The limitations of the VP2 gene segment in subgrouping were confirmed by phylogenetic analysis. The conserved sequence and polymorphism identified in this study may be helpful in the detection and genotyping of BKV. PMID:26640547

Surface deformation and friction characteristic of nano scratch at ductile-removal regime for optical glass BK7.

PubMed

Li, Chen; Zhang, Feihu; Ding, Ye; Liu, Lifei

2016-08-20

Nano scratch for optical glass BK7 based on the ductile-removal regime was carried out, and the influence rule of scratch parameters on surface deformation and friction characteristic was analyzed. Experimental results showed that, with increase of normal force, the deformation of burrs in the edge of the scratch was more obvious, and with increase of the scratch velocity, the deformation of micro-fracture and burrs in the edge of the scratch was more obvious similarly. The residual depth of the scratch was measured by atomic force microscope. The experimental results also showed that, with increase of normal force, the residual depth of the scratch increased linearly while the elastic recovery rate decreased. Furthermore, with increase of scratch velocity, the residual depth of the scratch decreased while the elastic recovery rate increased. The scratch process of the Berkovich indenter was divided into the cutting process of many large negative rake faces based on the improved cutting model, and the friction characteristic of the Berkovich indenter and the workpiece was analyzed. The analysis showed that the coefficient of friction increased and then tended to be stable with the increase of normal force. Meanwhile, the coefficient of friction decreased with the increase of scratch velocity, and the coefficients, k ln(v) and μ₀, were introduced to improve the original formula of friction coefficient.

Identification of B-K near edge x-ray absorption fine structure peaks of boron nitride thin films prepared by sputtering deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niibe, Masahito; Miyamoto, Kazuyoshi; Mitamura, Tohru

2010-09-15

Four {pi}{sup *} resonance peaks were observed in the B-K near edge x-ray absorption fine structure spectra of boron nitride thin films prepared by magnetron sputtering. In the past, these peaks have been explained as the K-absorption of boron atoms, which are present in environment containing nitrogen vacancies, the number of which is 1-3 corresponding to the three peaks at higher photon energy. However, the authors found that there was a strong correlation between the intensities of these three peaks and that of O-K absorption after wide range scanning and simultaneous measurement of nitrogen and oxygen K-absorptions of the BNmore » films. Therefore, the authors conclude that these three peaks at the higher energy side correspond to boron atoms bound to one-to-three oxygen atoms instead of three nitrogen atoms surrounding the boron atom in the h-BN structure. The result of the first-principles calculation with a simple cluster model supported the validity of this explanation.« less

In vivo synthesis of selenium nanoparticles by Halococcus salifodinae BK18 and their anti-proliferative properties against HeLa cell line.

PubMed

Srivastava, Pallavee; Braganca, Judith M; Kowshik, Meenal

2014-01-01

Nanoparticles synthesis by bacteria and yeasts has been widely reported, however, synthesis using halophilic archaea is still in a nascent stage. This study aimed at the intracellular synthesis of selenium nanoparticles (SeNPs) by the haloarchaeon Halococcus salifodinae BK18 when grown in the presence of sodium selenite. Crystallographic characterization of SeNPs by X-ray diffraction, Selected area electron diffraction, and transmission electron microscopy exhibited rod shaped nanoparticles with hexagonal crystal lattice, a crystallite domain size of 28 nm and an aspect ratio (length:diameter) of 13:1. Energy disruptive analysis of X-ray analysis confirmed the presence of selenium in the nano-preparation. The nitrate reductase enzyme assay and the inhibitor studies indicated the involvement of NADH-dependent nitrate reductase in SeNPs synthesis and metal tolerance. The SeNPs exhibited good anti-proliferative properties against HeLa cell lines while being non-cytotoxic to normal cell line model HaCat, suggesting the use of these SeNPs as cancer chemotherapeutic agent. This is the first study on selenium nanoparticles synthesis by haloarchaea. © 2014 American Institute of Chemical Engineers.

Prevalence of polyomavirus BK and JC infection and replication in 400 healthy blood donors.

PubMed

Egli, Adrian; Infanti, Laura; Dumoulin, Alexis; Buser, Andreas; Samaridis, Jacqueline; Stebler, Christine; Gosert, Rainer; Hirsch, Hans H

2009-03-15

The replication of BK virus (BKV) and JC virus (JCV) is linked to polyomavirus-associated nephropathy, hemorrhagic cystitis, and multifocal leukoencephalopathy in immunodeficient patients, but the behavior of these viruses in immunocompetent individuals has hardly been characterized. We used EIA to study samples obtained from 400 healthy blood donors aged 20-59 years for BKV- and JCV-specific antibodies against virus-like particles. We also studied BKV and JCV loads in plasma and urine among these individuals by use of real-time polymerase chain reaction. IgG seroprevalence was 82% (328 of 400 donors) for BKV and 58% (231 of400) for JCV. As age increased (age groups were divided by decade), the seroprevalence of BKV decreased from 87% (87 of 100) in the youngest group (aged 20-29 years) to 71% (71 of 100) in the oldest group (aged 50-59 years) (P = .006), whereas the seroprevalence of JCV increased from 50% (50 of 100) in the youngest group to 68% (68 of 100) in the oldest group (P = .06). Asymptomatic urinary shedding of BKV and JCV was observed in 28 (7%) and 75 (19%) of 400 subjects, respectively, with median viral loads of 3.51 and 4.64 log copies/mL, respectively (P < .001). Unlike urinary BKV loads, urinary JCV loads were positively correlated with IgG levels. The shedding of JCV was more commonly observed among individuals who were seropositive only for JCV, compared with individuals who were seropositive for both BKV and JCV, suggesting limited cross-protection from BKV immunity. Noncoding control regions were of archetype architecture in all cases, except for 1 rearranged JCV variant. Neither BKV nor JCV DNA was detected in plasma. Our study provides important data about polyomavirus infection and replication in healthy, immunocompetent individuals. These data indicate significant differences between BKV and JCV with respect to virus-host interaction and epidemiology.

Analysis of real-time mixture cytotoxicity data following repeated exposure using BK/TD models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Teng, S.; Tebby, C.

Cosmetic products generally consist of multiple ingredients. Thus, cosmetic risk assessment has to deal with mixture toxicity on a long-term scale which means it has to be assessed in the context of repeated exposure. Given that animal testing has been banned for cosmetics risk assessment, in vitro assays allowing long-term repeated exposure and adapted for in vitro – in vivo extrapolation need to be developed. However, most in vitro tests only assess short-term effects and consider static endpoints which hinder extrapolation to realistic human exposure scenarios where concentration in target organs is varies over time. Thanks to impedance metrics, real-timemore » cell viability monitoring for repeated exposure has become possible. We recently constructed biokinetic/toxicodynamic models (BK/TD) to analyze such data (Teng et al., 2015) for three hepatotoxic cosmetic ingredients: coumarin, isoeugenol and benzophenone-2. In the present study, we aim to apply these models to analyze the dynamics of mixture impedance data using the concepts of concentration addition and independent action. Metabolic interactions between the mixture components were investigated, characterized and implemented in the models, as they impacted the actual cellular exposure. Indeed, cellular metabolism following mixture exposure induced a quick disappearance of the compounds from the exposure system. We showed that isoeugenol substantially decreased the metabolism of benzophenone-2, reducing the disappearance of this compound and enhancing its in vitro toxicity. Apart from this metabolic interaction, no mixtures showed any interaction, and all binary mixtures were successfully modeled by at least one model based on exposure to the individual compounds. - Highlights: • We could predict cell response over repeated exposure to mixtures of cosmetics. • Compounds acted independently on the cells. • Metabolic interactions impacted exposure concentrations to the compounds.« less

Thickness and marking quality of different occlusal contact registration strips

PubMed Central

TOLEDO, Maria Fernanda de Souza Mauá Serapião; JÓIAS, Renata Pilli; MARQUES-IASI, Yves Santini; NEVES, Ana Christina Claro; RODE, Sigmar de Mello

2014-01-01

Objectives Evaluate the thickness and the marking quality of different occlusal contact registration strips (OCRS) and a possible correlation between them. Material and Methods The following OCRS were selected: Accufilm II, BK20, BK21, BK22, BK23, BK28, and BK31. The thickness was measured in three points of the OCRS with an electronic measuring device (TESA), and the mean was calculated. To produce the marks on the strips, composite resin specimens were adapted to a universal testing machine (Versat 2000) with 40 kgf load cell at a speed of 1.0 mm/min. The mark images were photographed with a stereoscopic microscope (Stemi SV11) and processed and analyzed by the 550-Leica Qwin® analyzer. Results Values (μm) found in the 1st and 2nd thickness measurements were: Accufilm II - 16.4 and 14.2; BK20 - 10.0 and 8.1; BK21 - 9.5 and 8.0; BK22 - 9.7 and 8.7; BK23 - 9.8 and 7.9; BK28 - 12.8 and 10.0; and BK31 - 8.4 and 8.0, respectively. The mean (mm2) values found in the mark areas were: Accufilm II - 0.078; BK20 - 0.035; BK21 - 0.045; BK22 - 0.012; BK23 - 0.022; BK28 - 0.024; and BK31 - 0.024. The results were submitted to the Kruskal-Wallis (p<0.05) and Pearson’s correlation tests. Conclusions Only in the 2nd measurement, the OCRS thickness observed was similar to the value indicated by the manufacturers; the Accufilm II and the BK28 strips showed the better marks; and no correlation was found between the thickness and the marking area. PMID:25591020

Ciprofloxacin decreased polyoma BK virus load in patients who underwent allogeneic hematopoietic stem cell transplantation.

PubMed

Leung, Anskar Y H; Chan, Maggie T L; Yuen, Kwok-Yung; Cheng, Vincent C C; Chan, Kwok-Hung; Wong, Chris L P; Liang, Raymond; Lie, Albert K W; Kwong, Yok-Lam

2005-02-15

Polyoma BK virus (BKV) is associated with hemorrhagic cystitis during hematopoietic stem cell transplantation (HSCT). The objective of this study was to test whether standard-dose ciprofloxacin might suppress reactivation of BKV infection during HSCT. Sixty-eight patients received ciprofloxacin or a cephalosporin as antibiotic prophylaxis after undergoing allogeneic HSCT. Urine samples were collected weekly from day 7 before HSCT to day 50 after HSCT. Laboratory investigations included quantification of BKV load and urinary ciprofloxacin levels and in vitro drug sensitivity of BKV. Twenty-two patients received ciprofloxacin, 21 received cephalosporins, 12 received concomitant corticosteroids and antibiotics (9 received ciprofloxacin, and 3 received cephalosporins), and 13 received interrupted ciprofloxacin therapy. Ciprofloxacin recipients developed a significantly lower peak BKV load, compared with cephalosporin recipients (median, 3x10(5) copies/mL vs. 2.6x10(9) copies/mL; P=.021), irrespective of concomitant receipt of corticosteroid therapy. Fewer ciprofloxacin recipients than cephalosporin recipients (P=.013) developed BKV viruria with a > or =3-log increase in BKV load during HSCT, which was associated with significantly more cases of hemorrhagic cystitis (8 of 29 patients with a peak increase of > or =3 log vs. 0 of 39 patients without a peak increase of this level; P<.001). Ciprofloxacin recipients excreted ciprofloxacin in urine at a mean 24-h rate of 71.7 microg/mL (range, 23.0-152.9 microg/mL), which was comparable with the in vitro inhibitory concentration of 125-250 microg/mL of ciprofloxacin found for 3 of 7 BKV isolates. Ciprofloxacin decreased urinary BKV reactivation after HSCT.

Polyomavirus BK and JC in individuals with chronic kidney failure, kidney transplantation, and healthy controls.

PubMed

Castro, Talita; Fink, Maria Cristina Domingues; Figueiredo, Marilia; Braz-Silva, Paulo Henrique; Pannuti, Cláudio Mendes; Ortega, Karem Lopez; Gallottini, Marina

2017-04-01

New clinical approaches to diagnose and monitor individuals with systemic diseases have been employed through the use of oral fluids. Polyomavirus BK (BKPyV) and JC (JCPyV) infect asymptomatically around 80% of general population worldwide remaining latent in the body. In case of immunosuppression, a replication can occur, leading to diseases. The aim of this study was to detect and quantify BKPyV and JCPyV in oral fluids of individuals with chronic kidney failure (CKF), kidney transplantation (KT) and controls compared with their detection in blood and urine, traditionally used for this test. Forty six subjects were included and distributed into 3 groups: 14 with CKF (Group 1), 12 with KT (Group 2) and 20 healthy individuals (Group 3). In a total, 315 samples were collected and analyzed through RT-PCR, being 151 of gingival crevicular fluid, 46 of saliva, 46 of mouthwash, 43 of blood and 29 of urine. All subjects from group 1 were positive for BKPyV in at least one collected samples and 14% were positive for JCPyV. In Group 2, 91.7% were positive for BKPyV and 51.7% for JCPyV. Among subjects of Group 3, 80% were positive for BKPyV and 45% for JCPyV. Oral fluids exhibited high prevalence of BKPyV and JCPyV and were equally efficient compared to urine and blood. The use of oral fluids to detect these polyomaviruses enhances positivity in screening, even in cases of absence of viremia and especially in individuals who are not able to urinate. Copyright © 2017 Elsevier B.V. All rights reserved.

Angiotensin I-converting enzyme inhibitors potentiate bradykinin's inotropic effects independently of blocking its inactivation.

PubMed

Minshall, R D; Erdös, E G; Vogel, S M

1997-08-04

The positive inotropic effects of bradykinin (BK) and 2 analogs resistant to angiotensin I-converting enzyme (ACE) were potentiated on isolated guinea pig atrial preparations by enalaprilat. The stable BK analogs, dextran-BK and [Hyp3-Tyr(Me)8]-BK, were as active as BK. Pretreatment for 5 min with enalaprilat augmented the maximal positive inotropic effect of [Hyp3-Tyr(Me)8]-BK 2.8-fold, from 19% to 53% and that of BK from 28% to 42% over baseline; inotropic responses to dextran-BK (1 microM) were similarly increased. The activity of atrial ACE, a zinc-requiring enzyme, was completely inhibited by 8-hydroxyquinoline-5-sulfonic acid (QSA, 10 mM), which raised the maximal inotropic effect of BK to 39% above baseline. This value rose to 67% when in addition to QSA, 1 microM enalaprilat was added; enalaprilat thus, potentiated the effects of BK independently of enzyme inhibition. The positive inotropic effects to BK and its analogs decline with time in the presence of these agonists. After 10 min of exposure, the response to 1 microM [Hyp3-Tyr(Me)8]-BK decreased to about half, and after 20 min, to 0. Enalaprilat, when present in the tissue bath, prevented the decline in inotropy; even after tachyphylaxis occurred, it reversed this decrease in activity when added. The effects of 1 microM [Hyp3-Tyr(Me)8]-BK, in the absence or presence of enalaprilat, were abolished by the BK B2 receptor antagonist icatibant (0.75 microM). The results indicate that ACE inhibitors, by potentiating the BK effects and blocking BK B2-receptor desensitization, may contribute to the beneficial cardiac effects of BK independently of blocking its inactivation.

77 FR 20321 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-04

... Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed... Deutschland GmbH (ECD) MBB-BK 117 A-3, MBB-BK 117 A-4, MBB- BK B-1, MBB-BK 117 B-2, and MBB-BK C-1 helicopters... Eurocopter Deutschland GmbH (ECD) Model MBB-BK 117 A-4 model. The EASA AD makes no mention of this model. The...

Up-Regulatory Effects of Curcumin on Large Conductance Ca2+-Activated K+ Channels

PubMed Central

Hei, Hongya; Li, Fangping; Wang, Yunman; Peng, Wen; Zhang, Xuemei

2015-01-01

Large conductance Ca2+-activated potassium channels (BK) are targets for research that explores therapeutic means to various diseases, owing to the roles of the channels in mediating multiple physiological processes in various cells and tissues. We investigated the pharmacological effects of curcumin, a compound isolated from the herb Curcuma longa, on BK channels. As recorded by whole-cell patch-clamp, curcumin increased BK (α) and BK (α+β1) currents in transfected HEK293 cells as well as the current density of BK in A7r5 smooth muscle cells in a dose-dependent manner. By incubating with curcumin for 24 hours, the current density of exogenous BK (α) in HEK293 cells and the endogenous BK in A7r5 cells were both enhanced notably, though the steady-state activation of the channels did not shift significantly, except for BK (α+β1). Curcumin up-regulated the BK protein expression without changing its mRNA level in A7r5 cells. The surface expression and the half-life of BK channels were also increased by curcumin in HEK293 cells. These effects of curcumin were abolished by MG-132, a proteasome inhibitor. Curcumin also increased ERK 1/2 phosphorylation, while inhibiting ERK by U0126 attenuated the curcumin-induced up-regulation of BK protein expression. We also observed that the curcumin-induced relaxation in the isolated rat aortic rings was significantly attenuated by paxilline, a BK channel specific blocker. These results show that curcumin enhances the activity of the BK channels by interacting with BK directly as well as enhancing BK protein expression through inhibiting proteasomal degradation and activating ERK signaling pathway. The findings suggest that curcumin is a potential BK channel activator and provide novel insight into its complicated pharmacological effects and the underlying mechanisms. PMID:26672753

Differential T cell response against BK virus regulatory and structural antigens: A viral dynamics modelling approach.

PubMed

Blazquez-Navarro, Arturo; Schachtner, Thomas; Stervbo, Ulrik; Sefrin, Anett; Stein, Maik; Westhoff, Timm H; Reinke, Petra; Klipp, Edda; Babel, Nina; Neumann, Avidan U; Or-Guil, Michal

2018-05-01

BK virus (BKV) associated nephropathy affects 1-10% of kidney transplant recipients, leading to graft failure in about 50% of cases. Immune responses against different BKV antigens have been shown to have a prognostic value for disease development. Data currently suggest that the structural antigens and regulatory antigens of BKV might each trigger a different mode of action of the immune response. To study the influence of different modes of action of the cellular immune response on BKV clearance dynamics, we have analysed the kinetics of BKV plasma load and anti-BKV T cell response (Elispot) in six patients with BKV associated nephropathy using ODE modelling. The results show that only a small number of hypotheses on the mode of action are compatible with the empirical data. The hypothesis with the highest empirical support is that structural antigens trigger blocking of virus production from infected cells, whereas regulatory antigens trigger an acceleration of death of infected cells. These differential modes of action could be important for our understanding of BKV resolution, as according to the hypothesis, only regulatory antigens would trigger a fast and continuous clearance of the viral load. Other hypotheses showed a lower degree of empirical support, but could potentially explain the clearing mechanisms of individual patients. Our results highlight the heterogeneity of the dynamics, including the delay between immune response against structural versus regulatory antigens, and its relevance for BKV clearance. Our modelling approach is the first that studies the process of BKV clearance by bringing together viral and immune kinetics and can provide a framework for personalised hypotheses generation on the interrelations between cellular immunity and viral dynamics.

Electronic Structure and Properties of Berkelium Iodates.

PubMed

Silver, Mark A; Cary, Samantha K; Garza, Alejandro J; Baumbach, Ryan E; Arico, Alexandra A; Galmin, Gregory A; Chen, Kuan-Wen; Johnson, Jason A; Wang, Jamie C; Clark, Ronald J; Chemey, Alexander; Eaton, Teresa M; Marsh, Matthew L; Seidler, Kevin; Galley, Shane S; van de Burgt, Lambertus; Gray, Ashley L; Hobart, David E; Hanson, Kenneth; Van Cleve, Shelley M; Gendron, Frédéric; Autschbach, Jochen; Scuseria, Gustavo E; Maron, Laurent; Speldrich, Manfred; Kögerler, Paul; Celis-Barros, Cristian; Páez-Hernández, Dayán; Arratia-Pérez, Ramiro; Ruf, Michael; Albrecht-Schmitt, Thomas E

2017-09-27

The reaction of 249 Bk(OH) 4 with iodate under hydrothermal conditions results in the formation of Bk(IO 3 ) 3 as the major product with trace amounts of Bk(IO 3 ) 4 also crystallizing from the reaction mixture. The structure of Bk(IO 3 ) 3 consists of nine-coordinate Bk III cations that are bridged by iodate anions to yield layers that are isomorphous with those found for Am III , Cf III , and with lanthanides that possess similar ionic radii. Bk(IO 3 ) 4 was expected to adopt the same structure as M(IO 3 ) 4 (M = Ce, Np, Pu), but instead parallels the structural chemistry of the smaller Zr IV cation. Bk III -O and Bk IV -O bond lengths are shorter than anticipated and provide further support for a postcurium break in the actinide series. Photoluminescence and absorption spectra collected from single crystals of Bk(IO 3 ) 4 show evidence for doping with Bk III in these crystals. In addition to luminescence from Bk III in the Bk(IO 3 ) 4 crystals, a broad-band absorption feature is initially present that is similar to features observed in systems with intervalence charge transfer. However, the high-specific activity of 249 Bk (t 1/2 = 320 d) causes oxidation of Bk III and only Bk IV is present after a few days with concomitant loss of both the Bk III luminescence and the broadband feature. The electronic structure of Bk(IO 3 ) 3 and Bk(IO 3 ) 4 were examined using a range of computational methods that include density functional theory both on clusters and on periodic structures, relativistic ab initio wave function calculations that incorporate spin-orbit coupling (CASSCF), and by a full-model Hamiltonian with spin-orbit coupling and Slater-Condon parameters (CONDON). Some of these methods provide evidence for an asymmetric ground state present in Bk IV that does not strictly adhere to Russel-Saunders coupling and Hund's Rule even though it possesses a half-filled 5f 7 shell. Multiple factors contribute to the asymmetry that include 5f electrons being present in

Treatment of BK virus-associated hemorrhagic cystitis with low-dose intravenous cidofovir in patients undergoing allogeneic hematopoietic cell transplantation

PubMed Central

Lee, Seung-Shin; Jung, Sung-Hoon; Ahn, Seo-Yeon; Kim, Jae-Yong; Jang, Hee-Chang; Kang, Seung-Ji; Jang, Mi-Ok; Yang, Deok-Hwan; Kim, Yeo-Kyeoung; Lee, Je-Jung; Kim, Hyeoung-Joon

2015-01-01

Background/Aims BK virus (BKV) has been associated with late-onset hemorrhagic cystitis (HC) in recipients of hematopoietic stem cell transplantation (HSCT). Cidofovir has been used at higher doses (3 to 5 mg/kg/wk) with probenecid prophylaxis; however, cidofovir may result in nephrotoxicity or cytopenia at high doses. Methods Allogeneic HSCT recipients with BKV-associated HC are treated with 1 mg/kg intravenous cidofovir weekly at our institution. A microbiological response was defined as at least a one log reduction in urinary BKV viral load, and a clinical response was defined as improvement in symptoms and stability or reduction in cystitis grade. Results Eight patients received a median of 4 weekly (range, 2 to 11) doses of cidofovir. HC occurred a median 69 days (range, 16 to 311) after allogeneic HSCT. A clinical response was detected in 7/8 patients (86%), and 4/5 (80%) had a measurable microbiological response. One patient died of uncontrolled graft-versus-host disease; therefore, we could not measure the clinical response to HC treatment. One microbiological non-responder had a stable BKV viral load with clinical improvement. Only three patients showed transient grade 2 serum creatinine toxicities, which resolved after completion of concomitant calcineurin inhibitor treatment. Conclusions Weekly intravenous low-dose cidofovir without probenecid appears to be a safe and effective treatment option for patients with BKV-associated HC. PMID:25750563

Treatment of BK virus-associated hemorrhagic cystitis with low-dose intravenous cidofovir in patients undergoing allogeneic hematopoietic cell transplantation.

PubMed

Lee, Seung-Shin; Ahn, Jae-Sook; Jung, Sung-Hoon; Ahn, Seo-Yeon; Kim, Jae-Yong; Jang, Hee-Chang; Kang, Seung-Ji; Jang, Mi-Ok; Yang, Deok-Hwan; Kim, Yeo-Kyeoung; Lee, Je-Jung; Kim, Hyeoung-Joon

2015-03-01

BK virus (BKV) has been associated with late-onset hemorrhagic cystitis (HC) in recipients of hematopoietic stem cell transplantation (HSCT). Cidofovir has been used at higher doses (3 to 5 mg/kg/wk) with probenecid prophylaxis; however, cidofovir may result in nephrotoxicity or cytopenia at high doses. Allogeneic HSCT recipients with BKV-associated HC are treated with 1 mg/kg intravenous cidofovir weekly at our institution. A microbiological response was defined as at least a one log reduction in urinary BKV viral load, and a clinical response was defined as improvement in symptoms and stability or reduction in cystitis grade. Eight patients received a median of 4 weekly (range, 2 to 11) doses of cidofovir. HC occurred a median 69 days (range, 16 to 311) after allogeneic HSCT. A clinical response was detected in 7/8 patients (86%), and 4/5 (80%) had a measurable microbiological response. One patient died of uncontrolled graft-versus-host disease; therefore, we could not measure the clinical response to HC treatment. One microbiological non-responder had a stable BKV viral load with clinical improvement. Only three patients showed transient grade 2 serum creatinine toxicities, which resolved after completion of concomitant calcineurin inhibitor treatment. Weekly intravenous low-dose cidofovir without probenecid appears to be a safe and effective treatment option for patients with BKV-associated HC.

The determination and arrangement of a combination of enzyme lactate dehydrogenase of bacteria Acinetobacter sp. as a device the identity important bacteria agent composts

NASA Astrophysics Data System (ADS)

Sukmawati, D.; Puspitaningrum, R.; Muzajjanah

2017-07-01

The number of garbage generated by the industry or society is a usual problem encountered by almost all urban centers, especially large cities such as Jakarta. Waste prevention strategy required quickly and accurately. One strategy for tackling the Junk was getting lactic acid-producing bacteria. It has been shown that lactic acid can increase the acceleration of organic matter such as an overhaul of lignin and cellulose as well as out causing toxic compounds arising from decay. This research will be conducted on the determination and characterization of the enzyme-producing compost bacteria LDH lactate dehydrogenase LDH - which in isolation from the garbage Landfill Rawasari. Methodology: Research carried out consists: isolation of lactic acid-producing bacteria; identification of microscopic, macroscopic and staining Gram; cellulose assay, and optimization of PCR conditions LDH enzymes producing bacteria. Isolation is performed by dilution method and the direct method. As many as 5-point sampling. Each stage is conducted from 10 grams of soil from the top surface of the compost. Isolation results obtained 100 isolate the bacteria. Base on the characteristic of macroscopic and microscopic observations retrieved 14 isolates of bacteria have shaped rods and brought forth a negative kind of Gram positive staining. Bacterial isolates with codes (BK1; BK3; BK4; BK5; BK6; BK7; BK8; BK9; BK10; BK11: BK12; BK 13). The potential bacteria with ability produce lactate dehydrogenase was BK1 and BK3. Base for analysis phylogenetic there was identification bacteria bak1 and bak3 where Acinetobacter sp.

Electrochemical layer-by-layer approach to fabricate mechanically stable platinum black microelectrodes using a mussel-inspired polydopamine adhesive.

PubMed

Kim, Raeyoung; Nam, Yoonkey

2015-04-01

Platinum black (PtBK) has long been used for microelectrode fabrication owing to its high recording performance of neural signals. The porous structure of PtBK enlarges the surface area and lowers the impedance, which results in background noise reduction. However, the brittleness of PtBK has been a problem in practice. In this work, we report mechanically stable PtBK microelectrodes using a bioinspired adhesive film, polydopamine (pDA), while maintaining the low impedance of PtBK. The pDA layer was incorporated into the PtBK structure through electrochemical layer-by-layer deposition. Varying the number of layers and the order of materials, multi-layered pDA-PtBK hybrids were fabricated and the electrical properties, both impedance and charge injection limit, were evaluated. Multilayered pDA-PtBK hybrids had electrical impedances as low as PtBK controls and charge injection limit twice larger than controls. For the 30 min-ultrasonication agitation test, impedance levels rarely changed for some of the pDA-PtBK hybrids indicating that the pDA improved the mechanical property of the PtBK structures. The pDA-PtBK hybrid microelectrodes readily recorded neural signals of cultured hippocampal neurons, where background noise levels and signal-to-noise were 2.43 ∼ 3.23 μVrms and 28.4 ∼ 69.1, respectively. The developed pDA-PtBK hybrid microelectrodes are expected to be applicable to neural sensors for neural prosthetic studies.

Electrochemical layer-by-layer approach to fabricate mechanically stable platinum black microelectrodes using a mussel-inspired polydopamine adhesive

NASA Astrophysics Data System (ADS)

Kim, Raeyoung; Nam, Yoonkey

2015-04-01

Objective. Platinum black (PtBK) has long been used for microelectrode fabrication owing to its high recording performance of neural signals. The porous structure of PtBK enlarges the surface area and lowers the impedance, which results in background noise reduction. However, the brittleness of PtBK has been a problem in practice. In this work, we report mechanically stable PtBK microelectrodes using a bioinspired adhesive film, polydopamine (pDA), while maintaining the low impedance of PtBK. Approach. The pDA layer was incorporated into the PtBK structure through electrochemical layer-by-layer deposition. Varying the number of layers and the order of materials, multi-layered pDA-PtBK hybrids were fabricated and the electrical properties, both impedance and charge injection limit, were evaluated. Main results. Multilayered pDA-PtBK hybrids had electrical impedances as low as PtBK controls and charge injection limit twice larger than controls. For the 30 min-ultrasonication agitation test, impedance levels rarely changed for some of the pDA-PtBK hybrids indicating that the pDA improved the mechanical property of the PtBK structures. The pDA-PtBK hybrid microelectrodes readily recorded neural signals of cultured hippocampal neurons, where background noise levels and signal-to-noise were 2.43 ∼ 3.23 μVrms and 28.4 ∼ 69.1, respectively. Significance. The developed pDA-PtBK hybrid microelectrodes are expected to be applicable to neural sensors for neural prosthetic studies.

Impact of low-level BK polyomavirus viremia on intermediate-term renal allograft function.

PubMed

Korth, Johannes; Widera, Marek; Dolff, Sebastian; Guberina, Hana; Bienholz, Anja; Brinkhoff, Alexandra; Anastasiou, Olympia Evdoxia; Kribben, Andreas; Dittmer, Ulf; Verheyen, Jens; Wilde, Benjamin; Witzke, Oliver

2018-02-01

BK polyomavirus (BKPyV)-associated nephropathy (PyVAN) is a significant cause of premature renal transplant failure. High-level BKPyV viremia is predictive for PyVAN; however, low-level BKPyV viremia does not necessarily exclude the presence of PyVAN. As data are limited regarding whether or not low-level BKPyV viremia has an effect on intermediate-term graft outcome, this study analyzes the impact of low-level BKPyV viremia on intermediate-term graft function and outcome compared with high-level viremia and non-viremic patients. All renal transplant patients received follow-up examinations at the Department of Nephrology, University Hospital Essen. Patients were screened for BKPyV viremia and stratified into three groups according to their maximum BKPyV load in serum (low-level viremia, high-level viremia, and no viremia). In 142 of 213 (67%) patients, BKPyV was never detected in serum; 42 of 213 (20%) patients were found positive for low-level viremia (≤10 4 copies/mL); and 29 of 213 (13%) patients showed high-level viremia (>10 4 copies/mL). No significant differences regarding transplant function and graft failure were observed between patients without BKPyV viremia (delta estimated glomerular filtration rate [eGFR] +0.1 mL/min [month 1 vs last visit at month 44]) and patients with low-level BKPyV viremia (delta eGFR -1.7 mL/min). In patients with high-level viremia, transplant function was significantly restricted (delta eGFR -6.5 mL/min) compared with low-level viremia until the last visit at 44 ± 9.7 months after transplantation. Although the graft function and graft loss were worse in the high-level viremia group compared with no viremia (eGFR 37 vs 45 mL/min), the difference was not significant. High-level viremia was associated with impaired graft function. In contrast, low-level BKPyV viremia had no significant impact on intermediate-term graft function. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

77 FR 44116 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-27

... Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA... Eurocopter Deutschland GmbH (ECD) MBB-BK 117 A-3, MBB-BK 117 A-4, MBB- BK B-1, MBB-BK 117 B-2, and MBB-BK C-1... directive (AD): 2012-14-14 Eurocopter Deutschland GmbH Helicopters: Amendment 39- 17128; Docket No. FAA-2012...

Functional characterization of BK virus-specific CD4+ T cells with cytotoxic potential in seropositive adults.

PubMed

Zhou, Wendi; Sharma, Madeva; Martinez, Joy; Srivastava, Tumul; Diamond, Don J; Knowles, Wendy; Lacey, Simon F

2007-09-01

BK polyomavirus (BKV) reactivation is associated with a failure of T cell immunity in kidney transplant patients, and may lead to BKV-associated nephropathy (BKVN) and loss of the allograft. BKV reactivation in hematopoietic stem cell transplant recipients is associated with hemorrhagic cystitis. We have investigated T cell responses to overlapping peptide mixtures corresponding to the whole BKV major T antigen (TAg) and major capsid protein (VP1) in peripheral blood mononuclear cell samples from a cohort of healthy BKV-seropositive subjects. The majority of these individuals possessed populations of both CD8(+) and CD4(+) T cells specific for these BKV antigens. After expansion in culture, the majority of the BKV-specific CD4(+) T cells, in addition to expressing CD40L (CD154), secreted both interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha, contained both granzyme A and granzyme B, and degranulated/mobilized CD107 in response to antigen-specific stimulation. These T cells thus represent potentially functional BKV-specific cytotoxic CD4(+) T lymphocytes. Secretion of both TNF-alpha and IFN-gamma by CD154(+)CD4(+) T cells on BKV-specific stimulation was associated with higher levels of granzyme B and a higher proportion of degranulating cells compared with CD154(+)CD4(+) T cells producing only IFN-gamma or neither cytokine. These healthy subjects also harbored populations of functional CD8(+) T cells specific for one or more of three newly defined HLA-A 02-restricted cytotoxic T lymphocyte epitopes within the BKV TAg as well as two HLA-A 02-restricted epitopes within the BKV VP1 we have previously described. The BKV-specific CD4(+) T cells characterized in this study may play a part in maintaining persistent memory T cell responses to the virus and thus contribute to the immune control of BKV in healthy individuals.

BK virus-specific T cells for use in cellular therapy show specificity to multiple antigens and polyfunctional cytokine responses.

PubMed

Blyth, Emily; Clancy, Leighton; Simms, Renee; Gaundar, Shivashni; O'Connell, Philip; Micklethwaite, Kenneth; Gottlieb, David J

2011-11-27

BK virus (BKV) infection causes hemorrhagic cystitis posthemopoietic stem-cell transplant and graft loss in renal transplant recipients. Reactivation occurs in up to 60% of patients in both groups. Treatment-related cellular immunosuppression is a major contributor to the development of BKV-related disease, but the targets of the immune response are not well characterized. Immunotherapy by adoptive transfer of cellular effectors has been shown to be effective in controlling and preventing some virus-related diseases in transplant recipients, particularly Epstein-Barr virus and cytomegalovirus. Infusion of BKV-specific T cells may potentially reconstitute functional BKV immunity and reduce clinical complications of BKV infection. BKV-specific T cells for clinical use in adoptive immunotherapy were generated using monocyte-derived dendritic cells pulsed with overlapping peptide mixes spanning the five BKV proteins VP1, VP2, VP3, large T antigen, and small T antigen. Phenotypic and functional characteristics of the cells were investigated as well as their antigen specificity. Expanded CD4(+) and CD8(+) cells responded to restimulation with BKV peptides principally from VP1, large T, or small T antigens; produced multiple cytokines; and showed cytotoxic activity against antigen-coated targets. Possible clinical uses for BKV-specific T cells generated using this method include immune reconstitution posthemopoietic stem-cell transplantation or prophylaxis and treatment of immune deficiency in renal transplant recipients, fulfilling the need for effective therapy for BKV-related hemorrhagic cystitis and renal dysfunction.

Potentiation of kinin analogues by ramiprilat is exclusively related to their degradation.

PubMed

Dendorfer, A; Reibetamann, S; Wolfrum, S; Raasch, W; Dominiak, P

2001-07-01

The potentiation of kinin actions represents a cardioprotective property of ACE inhibitors. Although a clear contribution to this effect is related to the inhibition of bradykinin (BK) breakdown, the high efficacy of potentiation and the ability of ACE inhibitors to provoke a B(2)-receptor-mediated response even after receptor desensitization has also triggered hypotheses concerning additional mechanisms of kinin potentiation. The application of kinin analogues with enhanced metabolic stability for the demonstration of degradation-independent mechanisms of potentiation, however, has yielded inconsistent results. Therefore, the relation between the susceptibility of B(2)-agonists to ACE and the potentiation of their actions by ACE inhibitors was investigated with the use of minimally modified kinin derivatives that varied in their degree of ACE resistance. The B(2)-agonists BK, D-Arg-[Hyp(3)]-BK, [Hyp,(3) Tyr(Me)(8)]-BK, [DeltaPhe(5)]-BK, [D-NMF(7)]-BK, and [Phe(8)psi(CH(2)-NH)Arg(9)]-BK were tested for degradation by purified rabbit ACE and for their potency in contracting the endothelium-denuded rabbit jugular vein in the absence and presence of ramiprilat. Purified ACE degraded D-Arg-[Hyp(3)]-BK and [Hyp,(3) Tyr(Me)(8)]-BK at 81% and 71% of BK degradation activity, respectively, whereas other peptides were highly ([DeltaPhe(5)]-BK) or completely ([D-NMF(7)]-BK, [Phe(8)psi(CH(2)-NH)Arg(9)]-BK) resistant. The EC(50) of BK-induced venoconstriction (1.15+/-0.2 nmol/L) was reduced by a factor of 5.7 in the presence of ramiprilat. Likewise, D-Arg-[Hyp(3)]-BK and [Hyp,(3) Tyr(Me)(8)]-BK were both significantly potentiated by a factor of 4.4, whereas the activities of the other agonists were not affected. Ramiprilat exerted no influence on the maximum contraction induced by any of the agonists. It is concluded that the potentiation of kinin analogues during ACE inhibition correlates quantitatively with the susceptibility of each substance to degradation by ACE. As such

Contractile effects of bradykinin on the isolated human small bronchus.

PubMed

Molimard, M; Martin, C A; Naline, E; Hirsch, A; Advenier, C

1994-01-01

Bradykinin (Bk) induced a contraction in all small bronchi samples (diameter, 0.5 to 1 mm) from 20 patients. pD2 was 7.7 +/- 0.1 (pD2 = -log EC50) and maximal effect (Emax) was 36.2 +/- 4.7% of the maximal response to acetylcholine. The B2 agonist [Hyp3TyrMe8]Bk contracted airway smooth muscle with a pD2 of 7.8 +/- 0.2 and an Emax of 39 +/- 9%. The B1 agonist [Sar1dPhe8desArg9]Bk induced only a weak contraction at 10(-6) M. The effect of Bk was abolished by the B2 (Hoe 140) but not by the B1 [Leu8desArg9]Bk receptor antagonist. Indomethacin 10(-6) M abolished Bk-induced contraction, suggesting that cyclooxygenase products are involved in Bk action. Capsaicin 10(-5) M, which selectively depletes C fibers from airway mediators through the ruthenium red pathway, and ruthenium red 10(-5) M significantly inhibited the concentration-response curves to Bk. However, tetrodotoxin (+/-)-CP-96,345, SR 48968, and atropine did not significantly affect Bk concentration-response curves, suggesting that nerve conduction, substance P (SP), neurokinin A (NKA), and acetylcholine release are not involved in Bk action. Our data indicate that Bk contracts human distal airway smooth muscle through the Bk B2 receptor and a cyclooxygenase pathway. This effect appears to involve capsaicin and ruthenium red pathways but neither acetylcholine nor NKA and SP release.

Characterization of kinin receptors by bioassays.

PubMed

Gobeil, F; Regoli, D

1994-08-01

1. Using the classical pharmacological criteria recommended by Schild, namely the order of potency of selective agonists (e.g., bradykinin, desArg9-bradykinin, [Hyp3]BK and [Aib7]BK) and the apparent affinity of competitive antagonists (e.g., DArg[Hyp3,DPhe7,Leu8]BK and WIN 64338), we have attempted to characterize B2 receptor subtypes. It has been shown that vascular tissues (e.g., dog carotid and renal arteries, rabbit jugular vein and rabbit aorta) are very sensitive to kinin agonists and antagonists (pD2 and pA2 values for BK and HOE 140 on B2 receptors are 8.5-10.1 and 9.2-9.4, respectively, and for desArg9BK and desArg9[Leu8]BK on B1 receptors they are 7.3-8.6 and 7.3-7.8, respectively). Mechanisms of action of kinins differ between pharmacological preparations. Kinin may act directly on the smooth muscle (e.g., rabbit jugular vein and rabbit aorta) as well as indirectly through other endogenous mediators such as nitric oxide (EDRF) (e.g., dog carotid and renal arteries) and prostaglandins (e.g., dog renal artery). 2. Pharmacological analysis of rabbit jugular vein (RJV) and guinea pig ileum (GPI) has revealed different sensitivities to certain synthetic analogs of BK and to competitive B2 receptor antagonists between the two tissues. 3. Agonist order of potency ([Hyp3]BK > BK > [Aib7]BK) obtained for RJV differed from that obtained for GPI (BK > or = [Aib7]BK > [Hyp3]BK). Competitive antagonists such as DArg[Hyp3, DPhe7, Leu8]BK and WIN 64338 discriminate in favor of B2A (RJV) and B2B (GPI) receptor subtypes, respectively. These data demonstrate the existence of B2 receptor subtypes. Correlation between data obtained in the present study and those reported for binding to the human B2 receptor support the view that the human receptor is similar to that of the rabbit.

Bradykinin regulates human colonic ion transport in vitro

PubMed Central

Baird, A W; Skelly, M M; O'Donoghue, D P; Barrett, K E; Keely, S J

2008-01-01

Background and purpose: Kinins are acknowledged as important regulators of intestinal function during inflammation; however, their effects on human intestinal ion transport have not been reported. Here, we used muscle-stripped human colonic tissue and cultured T84-cell monolayers to study bradykinin (BK) actions on human intestinal ion transport. Experimental approach: Ion transport was measured as changes in short-circuit current (Isc) across colonic epithelia mounted in Ussing chambers. Key results: In intact tissue, there was a distinct polarity to BK-elicited Isc responses. Whereas basolateral BK stimulated sustained responses (EC50=0.5±0.1 μM), those to apical BK were more rapid and transient (EC50=4.1±1.2 nM). In T84 cells, responses to both apical and basolateral BK were similar to those seen upon apical addition to intact tissues. Cross-desensitization between apical and basolateral domains was not observed. BK-induced responses were largely due to Cl− secretion as shown by their sensitivity to bumetanide and removal of Cl− from the bathing solution. Studies using selective agonists and antagonists indicate responses to BK are mediated by B2 receptors. Finally, responses to basolateral BK in intact tissues were inhibited by tetrodotoxin (1 μM), atropine (1 μM), capsaicin (100 μM) and piroxicam (10 μM). BK-stimulated prostaglandin (PG)E2 release from colonic tissue. Conclusions: BK stimulates human colonic Cl− secretion by activation of apical and basolateral B2 receptors. Responses to apical BK reflect a direct action on epithelial cells, whereas those to basolateral BK are amplified by stimulation of enteric nerves and PG synthesis. PMID:18604228

Bradykinin regulates osteoblast differentiation by Akt/ERK/NFκB signaling axis.

PubMed

Srivastava, Swati; Sharma, Kirti; Kumar, Narender; Roy, Partha

2014-12-01

Bradykinin (BK), a well known mediator of pain and inflammation, is also known to be involved in the process of bone resorption. The present study therefore evaluated the role of BK in osteoblast lineage commitment. Our data showed that BK inhibits the migration of bone marrow mesenchymal stem cells, but does not affect their viability. Moreover, BK also inhibits osteoblastic differentiation by significantly downregulating the levels of mRNAs for osteopontin, runX2, col24, osterix, osteocalcin genes and bone mineralization (P < 0.05). Further, BK was found to elicit the BK receptors (BDKR1 and BDKR2) mediated activation of ERK1/2 and Akt pathways, which finally led to the activation of NFκB. BK also promoted the osteoclast differentiation of bone marrow derived preosteoclast cells by upregulating the expression of c-fos, NFATC1, TRAP, clcn7, cathK, and OSCAR genes and increasing TRAP activity through NFκB pathway. In conclusion, our data suggest that BK decreases the differentiation of osteoblasts with concomitant increase in osteoclast formation and thus provides new insight into the mechanism of action of BK in modulating bone resorption. © 2014 Wiley Periodicals, Inc.

Computed tomography findings of human polyomavirus BK (BKV)-associated cystitis in allogeneic hematopoietic stem cell transplant recipients.

PubMed

Schulze, M; Beck, R; Igney, A; Vogel, M; Maksimovic, O; Claussen, C D; Faul, C; Horger, M

2008-12-01

Over 70% of the general population worldwide is positive for antibodies against polyomavirus hominis type 1 (BKV). Polyomavirus can be reactivated in immunocompromised patients and thereby induce urogenital tract infection, including cystitis. To describe the computed tomography (CT) findings of human polyomavirus-induced cystitis in adult patients after allogeneic hematopoietic stem cell transplantation (allogeneic HCT). The study population was a retrospective cohort of 11 consecutive adult patients (eight men, three women; age range 22-59 years, mean 42.9 years) who received allogeneic HCT between December 2003 and December 2007 and were tested positive for urinary BKV infection. All CT scans were evaluated with regard to bladder wall thickness, mucosal enhancement, distinct layering of thickened bladder wall, and presence of intravesical clots, perivesical stranding as well as attenuation values of intravesical urine. Clinical data concerning transplant and conditioning regimen variables and laboratory parameters were correlated with degree and extent of imaging findings. All patients had clinical signs of cystitis with different degrees of thickening of the urinary bladder wall. Well-delineated urinary bladder layers were present in six patients. Thickening of the urinary bladder wall was continuous in nine of 11 patients. Increased attenuation of intravesical urine was found in seven patients with hemorrhagic cystitis. Four patients had intraluminal clots. Perivesical stranding was not a major CT finding, occurring in a mild fashion in three of 11 patients. The clinical classification of hemorrhagic cystitis did not correlate with the analyzed imaging parameters. Patient outcome was not influenced by this infectious complication. CT findings in patients with polyomavirus BK cystitis consist of different degrees of bladder wall thickening usually with good delineation of all mural layers and increased mucosal enhancement. These findings are not specific for

Clinical Characteristics and Outcomes of Late-Onset BK Virus Nephropathy in Kidney and Kidney-Pancreas Transplant Recipients.

PubMed

Imlay, Hannah; Whitaker, Kathryn; Fisher, Cynthia E; Limaye, Ajit P

2018-05-29

BK virus nephropathy (BKPyVAN) is a major complication in kidney transplant recipients (KTR) and typically occurs within 1 year of transplant. Guidelines vary in recommendations for BKPyV screening beyond 1 year. A systematic characterization of risk factors and outcomes of late-onset (>1 year) BKPyVAN has not previously been reported. We retrospectively compared characteristics and outcomes of early- (<1 year) and late-onset BKPyVAN (definitive [biopsy-confirmed] or presumptive [plasma BKPyV >10,000 copies/mL]) in a cohort of 671 KTR and simultaneous kidney-pancreas transplant (SPK) recipients between 2008 and 2013 at a single US transplant center. Proportions were compared using Chi square or Fisher's exact test with p < 0.05 considered significant. BKPyVAN was diagnosed in 96 (14.3%) patients (proven 16.7%, presumptive 83.3%): 79 (82.3%) early- and 17 (17.7%) late-onset. The proportion with late-onset BKPyVAN was significantly higher among SPK than KTR (4 of 7 [57.1%] vs 13 of 89 [14.6%], p=0.017). Late-onset represented "de novo" infection (no BKPyV detection within the first year) in 14 (82.4%) and progression of earlier lower-grade BKPyV reactivation in 3 (17.6%). Clinical outcomes were similar for early- and late-onset BKPyVAN (p>0.05 all comparisons). In a pooled analysis of prior studies of BKPyVAN in SPK recipients, 62.9% (17 of 27) were late-onset. A significant proportion of BKPyVAN is late-onset, especially among SPK recipients, and supports a longer duration of BKPyV monitoring for SPK recipients than recommended in some guidelines. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Human plasma kallikrein-kinin system: Physiological and biochemical parameters

PubMed Central

Bryant, J.W.; Shariat-Madar, z

2016-01-01

The plasma kallikrein-kinin system (KKS) plays a critical role in human physiology. The KKS encompasses coagulation factor XII (FXII), the complex of prekallikrein (PK) and high molecular weight kininogen (HK). The conversion of plasma to kallikrein by the activated FXII and in response to numerous different stimuli leads to the generation of bradykinin (BK) and activated HK (HKa, an antiangiogenic peptide). BK is a proinflammatory peptide, a pain mediator and potent vasodilator, leading to robust accumulation of fluid in the interstitium. Systemic production of BK, HKa with the interplay between BK bound-BK receptors and the soluble form of HKa are key to angiogenesis and hemodynamics. KKS has been implicated in the pathogenesis of inflammation, hypertension, endotoxemia, and coagulopathy. In all these cases increased BK levels is the hallmark. In some cases, the persistent production of BK due to the deficiency of the blood protein C1-inhibitor, which controls FXII, is detrimental to the survival of the patients with hereditary angioedema (HAE). In others, the inability of angiotensin converting enzyme (ACE) to degrade BK leads to elevated BK levels and edema in patients on ACE inhibitors. Thus, the mechanisms that interfere with BK liberation or degradation would lead to blood pressure dysfunction. In contrast, anti-kallikrein treatment could have adverse effects in hemodynamic changes induced by vasoconstrictor agents. Genetic models of kallikrein deficiency are needed to evaluate the quantitative role of kallikrein and to validate whether strategies designed to activate or inhibit kallikrein may be important for regulating whole-body BK sensitivity. PMID:19689262

Neurophysiological mechanisms of bradykinin-evoked mucosal chloride secretion in guinea pig small intestine.

PubMed

Qu, Mei-Hua; Ji, Wan-Sheng; Zhao, Ting-Kun; Fang, Chun-Yan; Mao, Shu-Mei; Gao, Zhi-Qin

2016-02-15

To investigate the mechanism for bradykinin (BK) to stimulate intestinal secretomotor neurons and intestinal chloride secretion. Muscle-stripped guinea pig ileal preparations were mounted in Ussing flux chambers for the recording of short-circuit current (Isc). Basal Isc and Isc stimulated by BK when preincubated with the BK receptors antagonist and other chemicals were recorded using the Ussing chamber system. Prostaglandin E2 (PGE2) production in the intestine was determined by enzyme immunologic assay (EIA). Application of BK or B2 receptor (B2R) agonist significantly increased the baseline Isc compared to the control. B2R antagonist, tetrodotoxin and scopolamine (blockade of muscarinic receptors) significantly suppressed the increase in Isc evoked by BK. The BK-evoked Isc was suppressed by cyclooxygenase (COX)-1 or COX-2 specific inhibitor as well as nonselective COX inhibitors. Preincubation of submucosa/mucosa preparations with BK for 10 min significantly increased PGE2 production and this was abolished by the COX-1 and COX-2 inhibitors. The BK-evoked Isc was suppressed by nonselective EP receptors and EP4 receptor antagonists, but selective EP1 receptor antagonist did not have a significant effect on the BK-evoked Isc. Inhibitors of PLC, PKC, calmodulin or CaMKII failed to suppress BK-induced PGE2 production. The results suggest that BK stimulates neurogenic chloride secretion in the guinea pig ileum by activating B2R, through COX increasing PGE2 production. The post-receptor transduction cascade includes activation of PLC, PKC, CaMK, IP3 and MAPK.

Purification, structural characterization, and myotropic activity of a peptide related to des-Arg(9)-bradykinin from an elasmobranch fish, the little skate, Leucoraja erinacea.

PubMed

Anderson, W Gary; Leprince, Jérôme; Conlon, J Michael

2008-08-01

A bradykinin (BK)-related peptide was isolated from heat-denaturated plasma from an elasmobranch fish, the little skate, Leucoraja erinacea after incubation with porcine pancreatic kallikrein. The primary structure of the peptide (H-Gly-Ile-Thr-Ser-Trp-Leu-Pro-Phe-OH; skate BK) shows limited structural similarity to the mammalian B1 receptor agonist, des-Arg(9)-BK. The myotropic activities of synthetic skate BK, and the analog skate [Arg(9)]BK, were examined in isolated skate vascular and intestinal smooth muscle preparations. Skate BK produced a concentration-dependent constriction of the mesenteric artery (EC(50)=4.37x10(-8)M; maximum response=103.4+/-10.23% of the response to 60mM KCl) but the response to skate [Arg(9)]BK was appreciably weaker (response to 10(-6)M=73.0+/-23.4% of the response to 60mM KCl). Neither the first branchial gill arch nor the ventral aorta responded to either purified peptide. Skate BK also produced a concentration-dependent constriction of intestinal smooth muscle preparations (EC(50)=2.74x10(-7)M; maximum response 31.0+/-12.2% of the response to 10(-5)M acetylcholine). Skate [Arg(9)]BK was without effect on the intestinal preparation. The data provide evidence for the existence of the kallikrein-kinin system in a phylogenetically ancient vertebrate group and the greater potency of skate BK compared with the analog skate [Arg(9)]BK suggests that the receptor mediating vascular responses resembles the mammalian B1 receptor more closely than the B2 receptor.

Large-conductance voltage- and Ca2+-activated K+ channel regulation by protein kinase C in guinea pig urinary bladder smooth muscle

PubMed Central

Hristov, Kiril L.; Smith, Amy C.; Parajuli, Shankar P.; Malysz, John

2013-01-01

Large-conductance voltage- and Ca2+-activated K+ (BK) channels are critical regulators of detrusor smooth muscle (DSM) excitability and contractility. PKC modulates the contraction of DSM and BK channel activity in non-DSM cells; however, the cellular mechanism regulating the PKC-BK channel interaction in DSM remains unknown. We provide a novel mechanistic insight into BK channel regulation by PKC in DSM. We used patch-clamp electrophysiology, live-cell Ca2+ imaging, and functional studies of DSM contractility to elucidate BK channel regulation by PKC at cellular and tissue levels. Voltage-clamp experiments showed that pharmacological activation of PKC with PMA inhibited the spontaneous transient BK currents in native freshly isolated guinea pig DSM cells. Current-clamp recordings revealed that PMA significantly depolarized DSM membrane potential and inhibited the spontaneous transient hyperpolarizations in DSM cells. The PMA inhibitory effects on DSM membrane potential were completely abolished by the selective BK channel inhibitor paxilline. Activation of PKC with PMA did not affect the amplitude of the voltage-step-induced whole cell steady-state BK current or the single BK channel open probability (recorded in cell-attached mode) upon inhibition of all major Ca2+ sources for BK channel activation with thapsigargin, ryanodine, and nifedipine. PKC activation with PMA elevated intracellular Ca2+ levels in DSM cells and increased spontaneous phasic and nerve-evoked contractions of DSM isolated strips. Our results support the concept that PKC activation leads to a reduction of BK channel activity in DSM via a Ca2+-dependent mechanism, thus increasing DSM contractility. PMID:24352333

Neutral endopeptidase up-regulation in isolated human umbilical artery: involvement in desensitization of bradykinin-induced vasoconstrictor effects.

PubMed

Pelorosso, Facundo Germán; Halperin, Ana Verónica; Palma, Alejandro Martín; Nowak, Wanda; Errasti, Andrea Emilse; Rothlin, Rodolfo Pedro

2007-02-01

Previous reports show that bradykinin B(2) receptors mediate contractile responses induced by bradykinin (BK) in human umbilical artery (HUA). However, although it has been reported that BK-induced responses can desensitize in several inflammatory models, the effects of prolonged in vitro incubation on BK-induced vasoconstriction in HUA have not been studied. In isolated HUA rings, BK-induced responses after a 5-h in vitro incubation showed a marked desensitization compared with responses at 2 h. Inhibition of either angiotensin-converting enzyme (ACE) or neutral endopeptidase (NEP), both BK-inactivating enzymes, failed to modify responses to BK at 2 h. After 5 h, ACE inhibition produced only a slight potentiation of BK-induced responses. In contrast, BK-induced vasoconstriction at 5 h was markedly potentiated by NEP inhibition. Moreover, NEP activity, measured by hydrolysis of its synthetic substrate (Z-Ala-Ala-Leu-p-nitroanilide), showed a 2.4-fold increase in 5-h incubated versus 2-h incubated tissues, which was completely reversed by cycloheximide (CHX) treatment. Furthermore, CHX significantly potentiated BK-induced responses, suggesting that NEP-mediated kininase activity increase at 5 h depends on de novo protein synthesis. In addition, under NEP inhibition, CHX treatment failed to produce an additional potentiation of BK-induced vasoconstriction. Still, NEP up-regulation was confirmed by Western blot, showing a 2.1-fold increase in immunoreactive NEP in 5-h incubated versus 2-h incubated HUA. In summary, the present study provides strong pharmacological evidence that NEP is up-regulated and plays a key role in desensitization of BK-induced vasoconstriction after prolonged in vitro incubation in HUA. Our results provide new insights into the possible mechanisms involved in BK-induced response desensitization during sustained inflammatory conditions.

Immunochemical characterization of the O antigens of two Proteus strains, O8-related antigen of Proteus mirabilis 12 B-r and O2-related antigen of Proteus genomospecies 5/6 12 B-k, infecting a hospitalized patient in Poland.

PubMed

Drzewiecka, Dominika; Shashkov, Alexander S; Arbatsky, Nikolay P; Knirel, Yuriy A

2016-05-01

A hospitalized 73-year-old woman was infected with a Proteus mirabilis strain, 12 B-r, isolated from the place of injection of a blood catheter. Another strain, 12 B-k, recognized as Proteus genomospecies 5 or 6, was isolated from the patient's faeces, which was an example of a nosocomial infection rather than an auto-infection. Serological investigation using ELISA and Western blotting showed that strain 12 B-k from faeces belonged to the Proteus O2 serogroup. Strain 12 B-r from the wound displayed cross-reactions with several Proteus O serogroups due to common epitopes on the core or O-specific parts of the lipopolysaccharide. Studies of the isolated 12 B-r O-specific polysaccharide by NMR spectroscopy revealed its close structural similarity to that of Proteus O8. The only difference in 12 B-r was the presence of an additional GlcNAc-linked phosphoethanolamine residue, which creates a putative epitope responsible for the cross-reactivity with Pt. mirabilis O16. The new O-antigen form could appear as a result of adaptation of the bacterium to a changing environment. On the basis of the data obtained, we suggest division of the O8 serogroup into two subgroups: O8a for strains of various Proteus species that have been previously classified into the O8 serogroup, and O8a,b for Pt. mirabilis 12 B-r, where 'a' is a common epitope and 'b' is a phosphoethanolamine-associated epitope. These findings further confirm serological and structural heterogeneity of O antigens of Proteus strains isolated lately from patients in Poland.

BK Virus-Hemorrhagic Cystitis Following Allogeneic Stem Cell Transplantation: Clinical Characteristics and Utility of Leflunomide Treatment

PubMed Central

Park, Young Hoon; Lim, Joo Han; Yi, Hyeon Gyu; Lee, Moon Hee; Kim, Chul Soo

2016-01-01

Objective: BK virus-hemorrhagic cystitis (BKV-HC) is a potential cause of morbidity and mortality in patients having undergone allogeneic stem cell transplantation (Allo-SCT). We analyzed the clinical features of BKV-HC following Allo-SCT and reported the utility of leflunomide therapy for BKV-HC. Materials and Methods: From January 2005 to June 2014, among the 69 patients that underwent Allo-SCT in our institution, the patients who experienced BKV-HC were investigated retrospectively. Results: HC was observed in 30 patients (43.5%), and among them, 18 of the cases (26.1%) were identified as BKV-HC. The median age of the patients (12 males and 6 females) was 45 years (minimum-maximum: 13-63). Patients received Allo-SCT for acute myeloid leukemia (n=11), aplastic anemia (n=4), myelodysplastic syndrome (n=2), and non-Hodgkin lymphoma (n=1). The donor types were human leukocyte antigen (HLA)-matched sibling donor for six patients, HLA-matched unrelated donor for nine, and haploidentical familial donor for two. The median onset and duration of BKV-HC was on day 21 after transplantation (minimum-maximum: 7-97) and 22 days (minimum-maximum: 6-107). Eleven patients (62.1%) had grade I-II HC and seven patients (38.9%) had grade III-IV (high-grade) HC. Among the seven patients who had high-grade HC, one had complete response, one had partial response, and five had no response. Among the five nonresponders, one died of BKV-HC associated complications. The remaining four patients were treated with leflunomide, achieving complete response (n=2) and partial response (n=2). The median duration from the start of leflunomide therapy to response was 13 days (minimum-maximum: 8-17 days). All patients tolerated the leflunomide treatment well, with three patients having mild gastrointestinal symptoms, including anorexia and abdominal bloating. Conclusion: BKV-HC was commonly observed in patients with HC following Allo-SCT. In high-grade BKV-HC patients who do not respond to supportive

BK virus-hemorrhagic cystitis following allogeneic stem cell transplantation: Clinical characteristics and utility of leflunomide treatment.

PubMed

Park, Young Hoon; Lim, Joo Han; Yi, Hyeon Gyu; Lee, Moon Hee; Kim, Chul Soo

2016-04-18

BK virus-hemorrhagic cystitis (BKV-HC) is a potential cause of morbidity and mortality in patients having undergone allogeneic stem cell transplantation (Allo-SCT). We analyzed the clinical features of BKV-HC following Allo-SCT and reported the utility of leflunomide therapy for BKV-HC. From January 2005 to June 2014, among the 69 patients underwent Allo-SCT in our institution, the patients who experienced BKV-HC were investigated retrospectively. Hemorrhagic cystitis (HC) was observed in 30 patients (43.5%), and among them, 18 patients (26.1%) were identified as BKV-HC. The median age of the patients (12 males and 6 females) was 45 years (range, 13-63). Patients received Allo-SCT from acute myeloid leukemia (n=11), aplastic anemia (n=4), myelodysplastic syndrome (n=2), and non-Hodgkin lymphoma (n=1).The donor types were a HLA-matched sibling donor for 6 patients, HLA-matched unrelated donor for 9, and a haploidentical familial donor for 2. The median onset and duration of BKV-HC was on day 21 (range, 7-97) after transplantation and 22 days (range, 6-107). Eleven patients (62.1%) had grade I-II HC and seven patients (38.9%) had grade III-IV (high-grade) HC. Among the seven patients who had high-grade HC, one had complete response (CR), one partial response (PR), and five no response (NR). Among the five non-responders, one died of BKV-HC associated complications. The remaining four patients were treated with leflunomide, with achieving CR (n=2) and PR (n=2). The median duration from the start of leflunomide therapy to response was 13 days (range, 8-17 days). All patients tolerated the leflunomide treatment well, with three patients having mild gastrointestinal symptoms, including anorexia and abdominal bloating. BKV-HC was commonly observed in patients with HC following Allo-SCT. In high-grade BKV-HC patients who fail supportive care, leflunomide may be a feasible option without significant toxicity.

Sodium cyanate-induced opening of calcium-activated potassium currents in hippocampal neuron-derived H19-7 cells.

PubMed

Huang, Chin-Wei; Huang, Chao-Ching; Huang, Mei-Han; Wu, Sheng-Nan; Hsieh, Yi-Jung

2005-03-29

We investigated the chemical toxic agent sodium cyanate (NaOCN) on the large conductance calcium-activated potassium channels (BK(Ca)) on hippocampal neuron-derived H19-7 cells. The whole-cell and cell-attach configuration of patch-clamp technique were applied to investigate the BK(Ca) currents in H19-7 cells in the presence of NaOCN (0.3 mM). NaOCN activated BK(Ca) channels on H19-7 cells. The single-channel conductance of BK(Ca) channels was 138+/-7pS. The presence of NaOCN (0.3 mM) caused an obvious increase in open probability of BK(Ca) channels. NaOCN did not exert effect on the slope of the activation curve and stimulated the activity of BK(Ca) channels in a voltage-dependent fashion in H19-7 cells. The presence of paxilline or EGTA significantly reduced the BK(Ca) amplitude, in comparison with the presence of NaOCN. These findings suggest that during NaOCN exposure, the activation of BK(Ca) channels in neurons could be one of the ionic mechanisms underlying the decreased neuronal excitability and neurological disorders.

The Leaves of Broussonetia kazinoki Siebold Inhibit Atopic Dermatitis-Like Response on Mite Allergen-Treated Nc/Nga Mice.

PubMed

Lee, Hoyoung; Ha, Hyekyung; Lee, Jun Kyoung; Park, Sang-Joon; Jeong, Seung-Ii; Shin, Hyeun Kyoo

2014-09-01

Broussonetia kazinoki Siebold. (B. kazinoki) has long been used in the manufacture of paper in Asian countries. Although B. kazinoki leaves (BK) have been employed in dermatological therapy, use of BK has not been tested in patients with atopic dermatitis (AD). Using Nc/Nga mice, which are genetically predisposed to develop AD-like skin lesions, we confirmed the efficacy of BK in AD treatment. BK extract was applied topically to Dermatophagoides farinae-induced AD-like lesions in Nc/Nga mice, and the effects were assessed both clinically and by measuring skin thickness on the back and ears. We measured the effects of BK extract on plasma levels of IgE and IL-4. We also measured the ability of BK extract to inhibit the secretion of hTARC in HaCaT cells after stimulation by TNF-α and IFN-γ. We found that BK extract significantly reduced ear and dorsal skin thickness and the clinical signs of AD, as well as significantly down-regulating the plasma levels of IgE and IL-4 (p<0.01 for each comparison). Moreover, 500 μg/mL of BK extract inhibited hTARC secretion in HaCaT cells by activated TNF-α/IFN-γ by about 87%. These findings suggest that topical application of BK extract has excellent potential in the treatment of AD.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Churchill, M.; Orawski, A.T.; AchutaMurthy, P.N.

Several studies have suggested that the essentially complete degradation of circulating bradykinin (BK) in lung is mediated in part by peptidase(s) other than the well-characterized angiotensin converting enzyme (ACE). The authors report here that the isolated perfused rat lung can inactivate BK by sequential N-terminal cleavage. (/sup 3/H-2, 3-Pro) BK was perfused through the lung and the products in the perfusate identified by HPLC. In the absence of inhibitors, BK was 89-100% degraded with /sup 3/H-Pro/sup 2/-Pro/sup 3/ and /sup 3/H-Pro as the major products. The dipeptidylaminopeptidase IV (DAP IV) inhibitor, diprotein A (Ile-Pro-Ile), greatly reduced the Pro-Pro and Promore » peaks and produced a prominent BK/sub 2-7/ peak (or BK/sub 2-9/ peak if the ACE inhibitor, captopril, was also present). 2-Mercapto-ethanol, a rather specific inhibitor of aminopeptidase P (AP-P), prevented the release of Arg/sup 1/, producing major BK and/or BK/sub 1-7/ peaks. The neutral metalloendopeptidase inhibitor, phosphoramidon, had no effect on the pattern of degradation of BK by the perfused rat lung by the release of Arg/sup 1/ by AP-P followed by release of Pro/sup 2/-Pro/sup 3/ by DAP IV.« less

Human umbilical vein: involvement of cyclooxygenase-2 pathway in bradykinin B1 receptor-sensitized responses.

PubMed

Errasti, A E; Rey-Ares, V; Daray, F M; Rogines-Velo, M P; Sardi, S P; Paz, C; Podestá, E J; Rothlin, R P

2001-08-01

In isolated human umbilical vein (HUV), the contractile response to des-Arg9-bradykinin (des-Arg9-BK), selective BK B1 receptor agonist, increases as a function of the incubation time. Here, we evaluated whether cyclooxygenase (COX) pathway is involved in BK B1-sensitized response obtained in 5-h incubated HUV rings. The effect of different concentrations of indomethacin, sodium salicylate, ibuprofen, meloxicam, lysine clonixinate or NS-398 administrated 30 min before concentration-response curves (CRC) was studied. All treatments produced a significant rightward shift of the CRC to des-Arg9-BK in a concentration-dependent manner, which provides pharmacological evidence that COX pathway is involved in the BK B1 responses. Moreover, in this tissue, the NS-398 pKb (5.2) observed suggests that COX-2 pathway is the most relevant. The strong correlation between published pIC50 for COX-2 and the NSAIDs' pKbs estimated further supports the hypothesis that COX-2 metabolites are involved in BK B1 receptor-mediated responses. In other rings, indomethacin (30, 100 micromol/l) or NS-398 (10, 30 micromol/l) produced a significant rightward shift of the CRC to BK, selective BK B2 agonist, and its pKbs were similar to the values to inhibit BK B1 receptor responses, suggesting that COX-2 pathway also is involved in BK B2 receptor responses. Western blot analysis shows that COX-1 and COX-2 isoenzymes are present before and after 5-h in vitro incubation and apparently COX-2 does not suffer additional induction.

The relevance of kalikrein-kinin system via activation of B2 receptor in LPS-induced fever in rats.

PubMed

Soares, Denis de Melo; Santos, Danielle R; Rummel, Christoph; Ott, Daniela; Melo, Míriam C C; Roth, Joachim; Calixto, João B; Souza, Glória E P

2017-11-01

This study evaluated the involvement of endogenous kallikrein-kinin system and the bradykinin (BK) B 1 and B 2 receptors on LPS- induced fever and the POA cells involved in this response. Male Wistar rats received either i.v. (1 mg/kg), i.c.v. (20 nmol) or i.h. (2 nmol) injections of icatibant (B 2 receptor antagonist) 30 or 60 min, respectively, before the stimuli. DALBK (B 1 receptor antagonist) was given either 15min before BK (i.c.v.) or 30 min before LPS (i.v.). Captopril (5 mg/kg, sc.,) was given 1 h prior LPS or BK. Concentrations of BK and total kininogenon CSF, plasma and tissue kallikrein were evaluated. Rectal temperatures (rT) were assessed by telethermometry. Ca ++ signaling in POA cells was performed in rat pup brain tissue microcultures. Icatibant reduced LPS fever while, captopril exacerbated that response, an effect abolished by icatibant. Icatibant (i.h.) reduced fever to BK (i.h.) but not that induced by LPS (i.v.). BK increased intracellular calcium concentration in neurons and astrocytes. LPS increased levels of bradykinin, tissue kallikrein and total kininogen. BK (i.c.v.) increased rT and decreased tail skin temperature. Captopril potentiated BK-induced fever an effect abolished by icatibant. DALBK reduced the fever induced by BK. BK (i.c.v.) increased the CSF PGE 2 concentration. Effect abolished by indomethacin (i.p.). LPS activates endogenous kalikrein-kinin system leading to production of BK, which by acting on B 2 -receptors of POA cells causes prostaglandin synthesis that in turn produces fever. Thus, a kinin B 2 -receptor antagonist that enters into the brain could constitute a new and interesting strategy to treat fever. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of kinin receptors modulating neurogenic contractions of the mouse isolated vas deferens.

PubMed Central

Maas, J; Rae, G A; Huidobro-Toro, J P; Calixto, J B

1995-01-01

1. This study analyses the receptors mediating the effects of bradykinin (BK) and analogues on neurogenic twitch contractions of the mouse isolated vas deferens evoked, in the presence of captopril (3 microM), by electrical field stimulation with trains of 4 rectangular 0.5 ms pulses of supramaximal strength, delivered at a frequency of 10 Hz every 20 s. 2. BK (0.1-300 nM) induced a graded potentiation of twitches, with an EC50 (geometric mean and 95% confidence limits) of 4.5 nM (1.7-11.6) and an Emax of 315 +/- 19 mg per 10 mg of wet tissue (n = 6). Similar results were obtained in tissues challenged with Lys-BK, [Hyp3]-BK, Met,Lys-BK and the selective B2 receptor agonist [Tyr(Me)8]-BK (0.1-300 nM). 3. The selective B2 receptor antagonists, Hoe 140 (1-10 nM) and NPC 17731 (3-30 nM), caused graded rightward shifts of the curve to BK-induced twitch potentiation, yielding apparent pA2 values of 9.65 +/- 0.09 and 9.08 +/- 0.13, respectively, and Schild plot slopes not different from 1. Both antagonists (100 nM) failed to modify similar twitch potentiations induced by substance P (3 nM) or endothelin-1 (1 nM). Preincubation with the selective B1 receptor antagonist, [Leu8,des-Arg9]-BK (1 microM), increased the potentiating effect of BK on twitches at 30-300 nM. 4. In contrast to BK, the selective B1 receptor agonist, [des-Arg9]-BK (0.3-1000 nM) reduced the amplitude of twitches in a graded fashion, with an IC50 of 13.7 nM (10.4-16.1) and an Imax of 175 +/- 11 mg (n = 4).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7606350

Analysis of erectile responses to bradykinin in the anesthetized rat

PubMed Central

Edward, Justin A.; Pankey, Edward A.; Jupiter, Ryan C.; Lasker, George F.; Yoo, Daniel; Reddy, Vishwaradh G.; Peak, Taylor C.; Chong, Insun; Jones, Mark R.; Feintech, Samuel V.; Lindsey, Sarah H.

2015-01-01

The kallikrein-kinin system is expressed in the corpus cavernosa, and bradykinin (BK) relaxes isolated corpora cavernosal strips. However, erectile responses to BK in the rat have not been investigated in vivo. In the present study, responses to intracorporal (ic) injections of BK were investigated in the anesthetized rat. BK, in doses of 1–100 μg/kg ic, produced dose-related increases in intracavernosal pressure (ICP) and dose-related deceases in mean arterial pressure (MAP). When decreases in MAP were prevented by intravenous injections of angiotensin II (Ang II), increases in ICP, in response to BK, were enhanced. Increases in ICP, ICP/MAP ratio, and area under the curve and decreases in MAP in response to BK were inhibited by the kinin B2 receptor antagonist HOE-140 and enhanced by the angiotensin-converting enzyme (ACE) inhibitor captopril and by Ang-(1–7). Increases in ICP, in response to BK, were not attenuated by the nitric oxide (NO) synthase inhibitor (Nω-nitro-l-arginine methyl ester) or the soluble guanylate cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one) but were attenuated by the cyclooxygenase inhibitor, sodium meclofenamate. Decreases in MAP were not attenuated by either inhibitor. These data suggest that erectile responses are mediated by kinin B2 receptors and modulated by decreases in MAP. These data indicate that ACE is important in the inactivation of BK and that erectile and hypotensive responses are independent of NO in the penis or the systemic vascular bed. Erectile responses to cavernosal nerve stimulation are not altered by BK or HOE-140, suggesting that BK and B2 receptors do not modulate nerve-mediated erectile responses under physiologic conditions. These data suggest that erectile responses to BK are mediated, in part, by the release of cyclooxygenase products. PMID:26055796

Potentiation of the actions of bradykinin by angiotensin I-converting enzyme inhibitors. The role of expressed human bradykinin B2 receptors and angiotensin I-converting enzyme in CHO cells.

PubMed

Minshall, R D; Tan, F; Nakamura, F; Rabito, S F; Becker, R P; Marcic, B; Erdös, E G

1997-11-01

Part of the beneficial effects of angiotensin I-converting enzyme (ACE) inhibitors are due to augmenting the actions of bradykinin (BK). We studied this effect of enalaprilat on the binding of [3H]BK to Chinese hamster ovary (CHO) cells stably transfected to express the human BK B2 receptor alone (CHO-3B) or in combination with ACE (CHO-15AB). In CHO-15AB cells, enalaprilat (1 mumol/L) increased the total number of low-affinity [3H]BK binding sites on the cells at 37 degrees C, but not at 4 degrees C, from 18.4 +/- 4.3 to 40.3 +/- 11.9 fmol/10(6) cells (P < .05; Kd, 2.3 +/- 0.8 and 5.9 +/- 1.3 nmol/L; n = 4). Enalaprilat preserved a portion of the receptors in high-affinity conformation (Kd, 0.17 +/- 0.08 nmol/L; 8.1 +/- 0.9 fmol/10(6) cells). Enalaprilat decreased the IC50 of [Hyp3-Tyr(Me)8]BK, the BK analogue more resistant to ACE, from 3.2 +/- 0.8 to 0.41 +/- 0.16 nmol/L (P < .05, n = 3). The biphasic displacement curve of the binding of [3H]BK also suggested the presence of high-affinity BK binding sites. Enalaprilat (5 nmol to 1 mumol/L) potentiated the release of [3H]arachidonic acid and the liberation of inositol 1,4,5-trisphosphate (IP3) induced by BK and [Hyp3-Tyr(Me)8]BK. Moreover, enalaprilat (1 mumol/L) completely and immediately restored the response of the B2 receptor, desensitized by the agonist (1 mumol/L [Hyp3-Tyr(Me)8]BK); this effect was blocked by the antagonist, HOE 140. Finally, enalaprilat, but not the prodrug enalapril, decreased internalization of the receptor from 70 +/- 9% to 45 +/- 9% (P < .05, n = 7). In CHO-3B cells, enalaprilat was ineffective. ACE inhibitors in the presence of both the B2 receptor and ACE enhance BK binding, protect high-affinity receptors, block receptor desensitization, and decrease internalization, thereby potentiating BK beyond blocking its hydrolysis.

Hydrophobic interaction between contiguous residues in the S6 transmembrane segment acts as a stimuli integration node in the BK channel

PubMed Central

Carrasquel-Ursulaez, Willy; Contreras, Gustavo F.; Sepúlveda, Romina V.; Aguayo, Daniel; González-Nilo, Fernando

2015-01-01

Large-conductance Ca2+- and voltage-activated K+ channel (BK) open probability is enhanced by depolarization, increasing Ca2+ concentration, or both. These stimuli activate modular voltage and Ca2+ sensors that are allosterically coupled to channel gating. Here, we report a point mutation of a phenylalanine (F380A) in the S6 transmembrane helix that, in the absence of internal Ca2+, profoundly hinders channel opening while showing only minor effects on the voltage sensor active–resting equilibrium. Interpretation of these results using an allosteric model suggests that the F380A mutation greatly increases the free energy difference between open and closed states and uncouples Ca2+ binding from voltage sensor activation and voltage sensor activation from channel opening. However, the presence of a bulky and more hydrophobic amino acid in the F380 position (F380W) increases the intrinsic open–closed equilibrium, weakening the coupling between both sensors with the pore domain. Based on these functional experiments and molecular dynamics simulations, we propose that F380 interacts with another S6 hydrophobic residue (L377) in contiguous subunits. This pair forms a hydrophobic ring important in determining the open–closed equilibrium and, like an integration node, participates in the communication between sensors and between the sensors and pore. Moreover, because of its effects on open probabilities, the F380A mutant can be used for detailed voltage sensor experiments in the presence of permeant cations. PMID:25548136

Phenotypic and functional characterization of circulating polyomavirus BK VP1-specific CD8+ T cells in healthy adults.

PubMed

van Aalderen, Michiel C; Remmerswaal, Ester B M; Heutinck, Kirstin M; ten Brinke, Anja; Pircher, Hanspeter; van Lier, René A W; ten Berge, Ineke J M

2013-09-01

The human polyomavirus BK virus (BKV) establishes a latent and asymptomatic infection in the majority of the population. In immunocompromised individuals, the virus frequently (re)activates and may cause severe disease such as interstitial nephritis and hemorrhagic cystitis. Currently, the therapeutic options are limited to reconstitution of the antiviral immune response. T cells are particularly important for controlling this virus, and T cell therapies may provide a highly specific and effective mode of treatment. However, little is known about the phenotype and function of BKV-specific T cells in healthy individuals. Using tetrameric BKV peptide-HLA-A02 complexes, we determined the presence, phenotype, and functional characteristics of circulating BKV VP1-specific CD8(+) T cells in 5 healthy individuals. We show that these cells are present in low frequencies in the circulation and that they have a resting CD45RA(-) CD27(+) memory and predominantly CCR7(-) CD127(+) KLRG1(+) CD49d(hi) CXCR3(hi) T-bet(int) Eomesodermin(lo) phenotype. Furthermore, their direct cytotoxic capacity seems to be limited, since they do not readily express granzyme B and express only little granzyme K. We compared these cells to circulating CD8(+) T cells specific for cytomegalovirus (CMV), Epstein-Barr virus (EBV), and influenza virus (Flu) in the same donors and show that BKV-specific T cells have a phenotype that is distinct from that of CMV- and EBV-specific T cells. Lastly, we show that BKV-specific T cells are polyfunctional since they are able to rapidly express interleukin-2 (IL-2), gamma interferon (IFN-γ), tumor necrosis factor α, and also, to a much lower extent, MIP-1β and CD107a.

Phenotypic and Functional Characterization of Circulating Polyomavirus BK VP1-Specific CD8+ T Cells in Healthy Adults

PubMed Central

Remmerswaal, Ester B. M.; Heutinck, Kirstin M.; ten Brinke, Anja; Pircher, Hanspeter; van Lier, René A. W.; ten Berge, Ineke J. M.

2013-01-01

The human polyomavirus BK virus (BKV) establishes a latent and asymptomatic infection in the majority of the population. In immunocompromised individuals, the virus frequently (re)activates and may cause severe disease such as interstitial nephritis and hemorrhagic cystitis. Currently, the therapeutic options are limited to reconstitution of the antiviral immune response. T cells are particularly important for controlling this virus, and T cell therapies may provide a highly specific and effective mode of treatment. However, little is known about the phenotype and function of BKV-specific T cells in healthy individuals. Using tetrameric BKV peptide-HLA-A02 complexes, we determined the presence, phenotype, and functional characteristics of circulating BKV VP1-specific CD8+ T cells in 5 healthy individuals. We show that these cells are present in low frequencies in the circulation and that they have a resting CD45RA− CD27+ memory and predominantly CCR7− CD127+ KLRG1+ CD49dhi CXCR3hi T-betint Eomesoderminlo phenotype. Furthermore, their direct cytotoxic capacity seems to be limited, since they do not readily express granzyme B and express only little granzyme K. We compared these cells to circulating CD8+ T cells specific for cytomegalovirus (CMV), Epstein-Barr virus (EBV), and influenza virus (Flu) in the same donors and show that BKV-specific T cells have a phenotype that is distinct from that of CMV- and EBV-specific T cells. Lastly, we show that BKV-specific T cells are polyfunctional since they are able to rapidly express interleukin-2 (IL-2), gamma interferon (IFN-γ), tumor necrosis factor α, and also, to a much lower extent, MIP-1β and CD107a. PMID:23864628

1-O-hexadecyloxypropyl cidofovir (CMX001) effectively inhibits polyomavirus BK replication in primary human renal tubular epithelial cells.

PubMed

Rinaldo, Christine Hanssen; Gosert, Rainer; Bernhoff, Eva; Finstad, Solrun; Hirsch, Hans H

2010-11-01

Antiviral drugs for treating polyomavirus BK (BKV) replication in polyomavirus-associated nephropathy or hemorrhagic cystitis are of considerable clinical interest. Unlike cidofovir, the lipid conjugate 1-O-hexadecyloxypropyl cidofovir (CMX001) is orally available and has not caused detectable nephrotoxicity in rodent models or human studies to date. Primary human renal proximal tubular epithelial cells were infected with BKV-Dunlop, and CMX001 was added 2 h postinfection (hpi). The intracellular and extracellular BKV DNA load was determined by quantitative PCR. Viral gene expression was examined by quantitative reverse transcription-PCR, Western blotting, and immunofluorescence microscopy. We also examined host cell viability, proliferation, metabolic activity, and DNA replication. The titration of CMX001 identified 0.31 μM as the 90% effective concentration (EC(90)) for reducing the extracellular BKV load at 72 hpi. BKV large T antigen mRNA and protein expression was unaffected at 24 hpi, but the intracellular BKV genome was reduced by 90% at 48 hpi. Late gene expression was reduced by 70 and 90% at 48 and 72 hpi, respectively. Comparisons of CMX001 and cidofovir EC(90)s from 24 to 96 hpi demonstrated that CMX001 had a more rapid and enduring effect on BKV DNA and infectious progeny at 96 hpi than cidofovir. CMX001 at 0.31 μM had little effect on overall cell metabolism but reduced bromodeoxyuridine incorporation and host cell proliferation by 20 to 30%, while BKV infection increased cell proliferation in both rapidly dividing and near-confluent cultures. We conclude that CMX001 inhibits BKV replication with a longer-lasting effect than cidofovir at 400× lower levels, with fewer side effects on relevant host cells in vitro.

Development of a BK virus real-time quantitative assay using the bioMérieux analyte-specific reagents in plasma specimens.

PubMed

Rennert, Hanna; Fernandes, Helen; Gilani, Zahid; Sipley, John

2015-12-01

Viral load testing for BK virus (BKV) has become the standard of care for diagnosing BKV infection and monitoring therapy in kidney transplant patients. However, there are currently no US Food and Drug Administration-approved assays and no standardization among available tests. This study evaluated the performance of the analyte-specific reagent (ASR) BKV primers r-gene and probe r-gene reagents (bioMérieux, Marcy l'Étoile, France) soon to become available on the US market for accuracy, linearity, precision, analytical sensitivity, specificity, and correlation with the Qiagen (Germantown, MD) BKV ASR test using commercial material and patient plasma samples. The assay was linear from 204 to 3.92 million (2.31-6.6 log10) DNA copies/mL (coefficient of determination: R(2) =0.999). A dilution series demonstrated limits of detection and quantitation of 2.14 log10 and 2.30 log10 copies/mL (95% hit rate detection), respectively. Interrun precision was highly reproducible, with coefficients of variance ranging from 2.2% to 6.0%. A comparison of 34 matched samples showed a good agreement (R(2) = 0.87) between the bioMérieux BKV laboratory test and the Qiagen BKV ASR assay results, with an average negative bias (-0.28 log10 copies/mL). The laboratory-developed test with bioMérieux BKV reagents is a reliable and sensitive assay for BKV DNA quantitation compared with the Qiagen ASR test. Copyright© by the American Society for Clinical Pathology.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Özel, Gamze

Bivariate Kumaraswamy (BK) distribution whose marginals are Kumaraswamy distributions has been recently introduced. However, its statistical properties are not studied in detail. In this study, statistical properties of the BK distribution are investigated. We suggest that the BK could provide suitable description for the earthquakes characteristics of Turkey. We support this argument using earthquakesoccurred in Turkey between 1900 and 2009. We also find that the BK distribution simulates earthquakes well.

Antigen-specific T cell responses to BK polyomavirus antigens identify functional anti-viral immunity and may help to guide immunosuppression following renal transplantation

PubMed Central

Chakera, A; Bennett, S; Lawrence, S; Morteau, O; Mason, P D; O'Callaghan, C A; Cornall, R J

2011-01-01

Infection with the polyoma virus BK (BKV) is a major cause of morbidity following renal transplantation. Limited understanding of the anti-viral immune response has prevented the design of a strategy that balances treatment with the preservation of graft function. The proven utility of interferon-gamma enzyme-linked immunospot (ELISPOT) assays to measure T cell responses in immunocompetent hosts was the basis for trying to develop a rational approach to the management of BKV following renal transplantation. In a sample of transplant recipients and healthy controls, comparisons were made between T cell responses to the complete panel of BKV antigens, the Epstein–Barr virus (EBV) antigens, BZLF1 and EBNA1, and the mitogen phytohaemagglutinin (PHA). Correlations between responses to individual antigens and immunosuppressive regimens were also analysed. Antigen-specific T cell responses were a specific indicator of recent or ongoing recovery from BKV infection (P < 0·05), with responses to different BKV antigens being highly heterogeneous. Significant BKV immunity was undetectable in transplant patients with persistent viral replication or no history of BKV reactivation. Responses to EBV antigens and mitogen were reduced in patients with BKV reactivation, but these differences were not statistically significant. The T cell response to BKV antigens is a useful and specific guide to recovery from BKV reactivation in renal transplant recipients, provided that the full range of antigenic responses is measured. PMID:21671906

Kinin B1 receptor antagonists containing alpha-methyl-L-phenylalanine: in vitro and in vivo antagonistic activities.

PubMed

Gobeil, F; Charland, S; Filteau, C; Perron, S I; Neugebauer, W; Regoli, D

1999-03-01

-To protect from metabolism and to improve potency of the AcLys-[D-betaNal7,Ile8]desArg9-bradykinin (BK) (R 715), we prepared and tested 3 analogues containing alpha-methyl-L-Phe ([alphaMe]Phe) in position 5: these are the AcLys-[(alphaMe)Phe5,D-betaNal7, Ile8]desArg9BK (R 892), Lys-Lys-[(alphaMe)Phe5,D-betaNal7, Ile8]desArg9BK (R 913), and AcLys-Lys-[(alphaMe)Phe5,D-betaNal7, Ile8]desArg9BK (R 914). The new compounds were tested against the contractile effect induced by desArg9BK on 2 B1 receptor bioassays, the human umbilical vein, and the rabbit aorta. Their antagonistic activities were compared with those of the early prototypes (Lys-[Leu8]desArg9BK and [Leu8]desArg9BK) and with other recently described peptide antagonists. The 3 (alphaMe)Phe analogues showed high antagonistic potencies (pA2) at both the human (8.8, 7.7, and 8. 7, respectively) and rabbit (8.6, 7.8, and 8.6, respectively) B1 receptors. No antagonistic effects (pA2<5) were observed on the B2 receptors that mediate the contractile effects of BK on the human umbilical vein, the rabbit jugular vein, and the guinea pig ileum. Moreover, these new B1 antagonists were found to be resistant to in vitro degradation by purified angiotensin-converting enzyme from rabbit lung. The Nalpha-acetylated forms, R 892 and R 914, were resistant to aminopeptidases from human plasma. In vivo antagonistic potencies (ID50) of B1 receptor antagonists were evaluated in anesthetized lipopolysaccharide-treated (for B1 receptor) and nontreated (for B2 receptor) rabbits against the hypotensive effects of exogenous desArg9BK and BK. R 892 efficiently inhibited (ID50 2.8 nmol/kg IV) hypotension induced by desArg9BK without affecting that evoked by BK (ID50 >600 nmol/kg IV). Conversely, the peptide antagonists Lys-Lys-[Hyp3,Igl5,D-Igl7,Oic8]desArg9BK (B 9858) and DArg-[Hyp3,Thi5,D-Tic7,Oic8] desArg9BK (S 0765) showed dual B1/B2 receptor antagonism in vitro and in vivo. It is concluded that R 892 and congeners provide selective

Potentiation of the vascular response to kinins by inhibition of myocardial kininases.

PubMed

Dendorfer, A; Wolfrum, S; Schäfer, U; Stewart, J M; Inamura, N; Dominiak, P

2000-01-01

Inhibitors of angiotensin I-converting enzyme (ACE) are very efficacious in the potentiation of the actions of bradykinin (BK) and are able to provoke a B(2) receptor-mediated vasodilation even after desensitization of this receptor. Because this activity cannot be easily explained only by an inhibition of kinin degradation, direct interactions of ACE inhibitors with the B(2) receptor or its signal transduction have been hypothesized. To clarify the significance of degradation-independent potentiation, we studied the vasodilatory effects of BK and 2 degradation-resistant B(2) receptor agonists in the isolated rat heart, a model in which ACE and aminopeptidase P (APP) contribute equally to the degradation of BK. Coronary vasodilation to BK and to a peptidic (B6014) and a nonpeptidic (FR190997) degradation-resistant B(2) agonist was assessed in the presence or absence of the ACE inhibitor ramiprilat, the APP inhibitor mercaptoethanol, or both. Ramiprilat or mercaptoethanol induced leftward shifts in the BK dose-response curve (EC(50)=3.4 nmol/L) by a factor of 4.6 or 4.9, respectively. Combined inhibition of ACE and APP reduced the EC(50) of BK to 0.18 nmol/L (ie, by a factor of 19) but potentiated the activity of B6014 (EC(50)=1.9 nmol/L) only weakly without altering that of FR190997 (EC(50)=0.34 nmol/L). Desensitization of B(2) receptors was induced by the administration of BK (0.2 micromol/L) or FR190997 (0.1 micromol/L) for 30 minutes; the vascular reactivity to ramiprilat or increasing doses of BK was tested thereafter. After desensitization with BK, but not FR190997, an additional application of ramiprilat provoked a B(2) receptor-mediated vasodilation. High BK concentrations were still effective at the desensitized receptor. The process of desensitization was not altered by ramiprilat. These results show that in this model, all potentiating actions of ACE inhibitors on kinin-induced vasodilation are exclusively related to the reduction in BK breakdown and are

Characterization of bradykinin receptors in human lung fibroblasts using the binding of 3[H][Des-Arg10,Leu9]kallidin and [3H]NPC17731.

PubMed

Zhang, S P; Codd, E E

1998-01-01

Bradykinin (BK) receptors are involved in pain and inflammation. Two BK receptor subtypes, B1 and B2, have been defined based on their pharmacological properties. Both B1 and B2 receptors are G-protein coupled membrane receptors. B1 receptors are present in smooth muscle tissue, whereas B2 receptors are found in both smooth muscle tissue and neurons. [Des-Arg10,Leu9]kallidin (DALKD) is a selective B1 receptor antagonist, and NPC17731 is a selective B2 receptor antagonist. To develop binding assays for the two known BK receptor subtypes, [3H]DALKD and [3H]NPC17731 were used as selective ligands for B1 and B2 receptors respectively. Both ligands bound to the CCD-16 human lung fibroblast membranes reaching equilibrium at 25 degrees C within 30 min. Binding was stable for at least 60 min. The Kd of [3H]DALKD was 0.33 nM and Bmax was 52 fmol/mg membrane protein. The Kd of [3H]NPC17731 was 0.39 nM and Bmax was 700 fmol/mg membrane protein. Competition for [3H]DALKD binding with BK receptor agonists was in the order: [des-Arg10]KD (DAKD) > KD > [des-Arg9]BK (DABK) > BK, and competition for [3H]DALKD binding with BK receptor antagonists was in the order: DALKD > [des-Arg10]Hoe 140 (DAHoe 140) > [des-Arg9,Leu8]BK (DALBK) > NPC17731 > Hoe 140 > DNMFBK, suggesting that [3H]DALKD bound selectively to B1 receptors. By contrast, competition for [3H]NPC17731 binding by BK agonists was in the order: BK > KD > DAKD > DABK, and competition for [3H]NPC17731 binding by BK antagonists was in the order: NPC17731 = Hoe 140 > DNMFBK > DAHoe 140 > DALBK > DALKD, indicating that [3H]NPC17731 labeled B2 receptors selectively. These results demonstrate that [3H]DALKD and [3H]NPC17731 can be used with CCD-16 human lung fibroblast membranes to provide a pair of binding assays for the simultaneous evaluation of B1 and B2 BK receptor subtypes.

Cardiovascular and vasoconstrictive actions of skate bradykinin in the little skate, Leucoraja erinacea (Elasmobranchii).

PubMed

Dasiewicz, Patricia J; Conlon, J Michael; Anderson, W Gary

2011-11-01

The vasoconstrictive and cardiovascular actions of a recently identified bradykinin (BK)-related peptide (Gly-Ile-Thr-Ser-Trp-Leu-Pro-Phe) from the little skate, Leucoraja erinacea were examined in the unanesthetised little skate. Intra-arterial administration of a skate BK (0.1-1 nmolkg(-1)) produced a hypertensive response with a rise in blood pressure reaching a maximum elevation of 28.7±4.8% over baseline (P<0.05, n=8) that was sustained for at least 12 min following administration of a 1 and 0.3 nmolkg(-1) dose of skate BK. Further, in vivo administration of 1 nmolkg(-1) skate BK induced a significant delayed increase in stroke volume (reaching a maximum of 54.4±14.7% above baseline) without significant effect on either cardiac output or heart rate. In vitro, skate BK constricted the 1st branchial, mesenteric (EC(50) 2.7×10(-9)M) and coeliac (EC(50) 3.1×10(-9)M) arterial preparations of the skate. In contrast, skate [Arg(9)]BK, the mammalian B(1) receptor agonist des-[Arg(9)]BK, and the mammalian B(2) receptor antagonist HOE-140 failed to induce vasoconstriction in these isolated arterial preparations. The vasoconstrictor actions of skate BK in the isolated mesenteric, coeliac and branchial arterial preparations were significantly inhibited when co-administrated with esculetin and phentolamine. Indomethacin also inhibited the vasoconstrictor actions of skate BK in the isolated branchial artery. We conclude that, as in mammals and teleost fish, multiple pathways involving at least the alpha adrenergic and leukotriene synthesis pathway are involved in mediating the vasoconstrictive actions of BK in vascular smooth muscle of the little skate. Copyright © 2011 Elsevier Inc. All rights reserved.

Bradykinin B1 and B2 receptors, tumour necrosis factor α and inflammatory hyperalgesia

PubMed Central

Poole, S; Lorenzetti, B B; Cunha, J M; Cunha, F Q; Ferreira, S H

1999-01-01

The effects of BK agonists and antagonists, and other hyperalgesic/antihyperalgesic drugs were measured (3 h after injection of hyperalgesic drugs) in a model of mechanical hyperalgesia (the end-point of which was indicated by a brief apnoea, the retraction of the head and forepaws, and muscular tremor). DALBK inhibited responses to carrageenin, bradykinin, DABK, and kallidin. Responses to kallidin and DABK were inhibited by indomethacin or atenolol and abolished by the combination of indomethacin+atenolol. DALBK or HOE 140, given 30 min before, but not 2 h after, carrageenin, BK, DABK and kallidin reduced hyperalgesic responses to these agents. A small dose of DABK+a small dose of BK evoked a response similar to the response to a much larger dose of DABK or BK, given alone. Responses to BK were antagonized by HOE 140 whereas DALBK antagonized only responses to larger doses of BK. The combination of a small dose of DALBK with a small dose of HOE 140 abolished the response to BK. The hyperalgesic response to LPS (1 μg) was inhibited by DALBK or HOE 140 and abolished by DALBK+HOE 140. The hyperalgesic response to LPS (5 μg) was not antagonized by DALBK+HOE 140. These data suggest: (a) a predominant role for B2 receptors in mediating hyperalgesic responses to BK and to drugs that stimulate BK release, and (b) activation of the hyperalgesic cytokine cascade independently of both B1 and B2 receptors if the hyperalgesic stimulus is of sufficient magnitude. PMID:10188975

Morphological, Histochemical, Immunohistochemical, and Ultrastructural Characterization of Tumors and Dysplastic and Non-Neoplastic Lesions Arising in BK Virus/tat Transgenic Mice

PubMed Central

Altavilla, Giuseppe; Trabanelli, Cecilia; Merlin, Michela; Caputo, Antonella; Lanfredi, Massimo; Barbanti-Brodano, Giuseppe; Corallini, Alfredo

1999-01-01

To study the role in AIDS pathogenesis of the human immunodeficiency virus type 1 (HIV-1) Tat protein, a transactivator of viral and cellular genes, we generated transgenic mice with a recombinant DNA containing BK virus (BKV) early region and the HIV-1 tat gene, directed by its own promoter-enhancer. DNA hybridization revealed that the transgene is stably maintained in all organs of transgenic mice as a tandem insertion in a number of copies ranging from 5 to 20 per cell. In addition, tat and BKV RNA were expressed in all tissues. Transgenic mice developed three types of lesions: 1) tumors, 2) hyperplastic and dysplastic lesions, and 3) non-neoplastic lesions. Tumors of different histotypes, such as lymphomas, adenocarcinomas of skin glands, leiomyosarcomas, skin squamous cell carcinomas, hepatomas, hepatocarcinomas, and cavernous liver hemangiomas, developed in 29% of transgenic animals. The majority of tumors were malignant, invasive, and producing metastases. Conversely, tumors of only two histotypes (lymphomas and adenocarcinomas of skin glands) appeared in control mice. Hyperplastic and dysplastic lesions were more frequent in transgenic than in control mice and involved the skin or its adnexes, the liver and the rectum, indicating multiple targets for the activity of the transgene. Pyelonephritis, frequently complicated with hydronephrosis, inflammatory eye lesions, and amyloid depositions represented the most frequent non-neoplastic lesions detected in transgenic mice. Many of the pathological findings observed in this animal model are comparable to similar lesions appearing in AIDS patients, suggesting a relevant role for Tat in the pathogenesis of such lesions during the course of AIDS. PMID:10233861

Efficacy and safety of leflunomide for the treatment of BK virus-associated hemorrhagic cystitis in allogeneic hematopoietic stem cell transplantation recipients.

PubMed

Chen, Xin-Chuan; Liu, Ting; Li, Jian-Jun; He, Chuan; Meng, Weng-Tong; Huang, Rui

2013-01-01

BK virus-associated hemorrhagic cystitis (BKV-HC) is a severe complication after allogeneic hematopoietic stem cell transplantation. So far, no specific antiviral drug with proven efficacy has been approved for treating BKV-HC. Leflunomide is an immunosuppressive drug with antiviral activity and has been used in treating BKV-associated nephropathy after renal transplantation. This is the first report on the efficacy and safety of leflunomide in the treatment of BKV-HC. From January 2006 to January 2009, 89 patients received allogeneic hematopoietic stem cell transplantation, and among them, 18 patients were identified as having BKV-HC, with a 20% cumulative incidence. Fourteen patients were treated with oral leflunomide. Three days of 100 mg/day leflunomide was used as loading doses and followed by maintenance doses of 20 mg/day. The urinary BKV-DNA load was monitored weekly by real-time quantitative PCR. The efficacy was evaluated on day 20 after leflunomide treatment. Seven patients (50%) achieved complete remission, 5 patients (35.7%) achieved partial remission, and 2 patients (14.3%) had more than a 1-log reduction in urinary BKV-DNA loads after treatment. During the leflunomide treatment, the graft-versus-host disease of the patients did not progress, and the dosages of the immunosuppressant were reduced simultaneously. One patient discontinued treatment because of intolerable gastrointestinal symptoms. Neutropenia occurred in 2 cases. These preliminary data suggest that leflunomide may be a potentially effective medication for treating BKV-HC without significant toxicity, but evidence supporting its use requires randomized controlled trials. Copyright © 2013 S. Karger AG, Basel.

Role of the BK channel (KCa1.1) during activation of electrogenic K+ secretion in guinea pig distal colon

PubMed Central

Zhang, Jin; Halm, Susan T.

2012-01-01

Secretagogues acting at a variety of receptor types activate electrogenic K+ secretion in guinea pig distal colon, often accompanied by Cl− secretion. Distinct blockers of KCa1.1 (BK, Kcnma1), iberiotoxin (IbTx), and paxilline inhibited the negative short-circuit current (Isc) associated with K+ secretion. Mucosal addition of IbTx inhibited epinephrine-activated Isc (epiIsc) and transepithelial conductance (epiGt) consistent with K+ secretion occurring via apical membrane KCa1.1. The concentration dependence of IbTx inhibition of epiIsc yielded an IC50 of 193 nM, with a maximal inhibition of 51%. Similarly, IbTx inhibited epiGt with an IC50 of 220 nM and maximal inhibition of 48%. Mucosally added paxilline (10 μM) inhibited epiIsc and epiGt by ∼50%. IbTx and paxilline also inhibited Isc activated by mucosal ATP, supporting apical KCa1.1 as a requirement for this K+ secretagogue. Responses to IbTx and paxilline indicated that a component of K+ secretion occurred during activation of Cl− secretion by prostaglandin-E2 and cholinergic stimulation. Analysis of KCa1.1α mRNA expression in distal colonic epithelial cells indicated the presence of the ZERO splice variant and three splice variants for the COOH terminus. The presence of the regulatory β-subunits KCaβ1 and KCaβ4 also was demonstrated. Immunolocalization supported the presence of KCa1.1α in apical and basolateral membranes of surface and crypt cells. Together these results support a cellular mechanism for electrogenic K+ secretion involving apical membrane KCa1.1 during activation by several secretagogue types, but the observed K+ secretion likely required the activity of additional K+ channel types in the apical membrane. PMID:23064759

Big-conductance Ca2+-activated K+ channels in physiological and pathophysiological urinary bladder smooth muscle cells

PubMed Central

Parajuli, Shankar P.; Zheng, Yun-Min; Levin, Robert; Wang, Yong-Xiao

2016-01-01

ABSTRACT Contraction and relaxation of urinary bladder smooth muscle cells (UBSMCs) represent the important physiological functions of the bladder. Contractile responses in UBSMCs are regulated by a number of ion channels including big-conductance Ca2+- activated K+ (BK) channels. Great progress has been made in studies of BK channels in UBSMCs. The intent of this review is to summarize recent exciting findings with respect to the functional interactions of BK channels with muscarinic receptors, ryanodine receptors (RyRs) and inositol triphosphate receptors (IP3Rs) as well as their functional importance under normal and pathophysiological conditions. BK channels are highly expressed in UBSMCs. Activation of muscarinic M3 receptors inhibits the BK channel activity, facilitates opening of voltage-dependent Ca2+ (CaV) channels, and thereby enhances excitability and contractility of UBSMCs. Signaling molecules and regulatory mechanisms involving RyRs and IP3Rs have a significant effect on functions of BK channels and thereby regulate cellular responses in UBSMCs under normal and pathophysiological conditions including overactive bladders. Moreover, BK channels may represent a novel target for the treatment of bladder dysfunctions. PMID:27101440

Treatment of BK virus-associated hemorrhagic cystitis in pediatric hematopoietic stem cell transplant recipients with cidofovir: a single-center experience.

PubMed

Kwon, H J; Kang, J H; Lee, J W; Chung, N-G; Kim, H-K; Cho, B

2013-12-01

BK virus (BKV)-associated hemorrhagic cystitis (BKV-HC) is a severe complication after hematopoietic stem cell transplantation (HSCT). Cidofovir (CDV) has emerged as an effective agent for the treatment of BKV nephropathy, but its use for BKV-HC in pediatric HSCT recipients has not yet been established as a standard therapy. We retrospectively investigated the efficacy and safety of CDV therapy for patients with BKV-HC at a single institution and analyzed the clinical management outcomes. From April 2009 to July 2011, 12 patients developed BKV-HC at a median of 37 days after transplant (range 15-59 days). The cumulative incidence was 9% and the median peak of the urine BKV load was 2.5 × 10(10) copies/mL (range 1.4 × 10(9) -1.2 × 10(11) copies/mL). Eleven patients received intravenous CDV (5 mg/kg/dose, with probenecid), whereas 1 patient received CDV (5 mg/kg/dose, without probenecid) intravesically. The median duration of therapy was 25 days (range 9-73 days), and a median of 2 doses was given (range 1-4). A reduction of ≥ 1 log in the BKV load was found in 11 patients, while 1 patient did not have any significant change in BKV load. Clinical improvement was observed in all cases, and no HC-related death was observed. CDV-related toxicity occurred in 1 patient (8%) and spontaneously resolved. CDV appears to be an effective and safe treatment for BKV-HC in pediatric HSCT recipients, but prospective trials are warranted to support its use. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Fabrication of 8×8 MMI optical coupler in BK7 by ion-exchange

NASA Astrophysics Data System (ADS)

Li, Xia; Li, Xi-Hua; Zhou, Qiang; Jiang, Xiao-Qing; Yang, Jian-Yi; Wang, Ming-Hua

2005-01-01

The planar waveguide optical couplers are of prime importance in optical communication and optical signal processing system. Comparing with the optical fiber coupler (OFC) which fabricated by fused biconical taper technology, the planar waveguide couplers are more compact size, lower loss, better uniformity, easier manufacture and integration. Multimode interference (MMI) couplers have many advantages, such as compact size, wavelength and polarization insensitivity, fabrication tolerances and low loss, etc., which concentrate more and more attention. Conventional MMI devices are based on the uniform index waveguides. When the number of input/output waveguides becomes larger, the intrinsic propagation constant error, which will cause bad uniformity of output power, can"t be neglected. In fact, most waveguide devices are graded-index. With the enhanced compatibility of MMI coupler, the performance can be improved at the same time. Prior study shows that graded-index MMI couplers reach the best performance under certain index contrast. Among many available materials, glass is chosen to be the substrate of the coupler, because of its good features, such as low loss, ease fabrication, cheap cost, and so on. In this paper, an 8×8 MMI optical coupler is designed based on the principle of graded-index MMI. The coupler is composed of a waveguide, which is designed to support a large number of modes, and several access (usually single-mode) waveguides, which are used to launch light into and recover light from that multimode waveguide. The total length of the device is less than 3.5 centimeter, including S-bends which lead the multiple images to the output of the device with the spacing D=250μm to make the device fiber compatible. In this paper, we describe an experimental realization of the 8×8 graded-index MMI optical coupler and the measurement of its performance with the testing laser of the wavelength of 1.55μm. The device is fabricated by ion-exchange on BK7 glass

Characterization of kinin receptors modulating neurogenic contractions of the mouse isolated vas deferens.

PubMed

Maas, J; Rae, G A; Huidobro-Toro, J P; Calixto, J B

1995-04-01

1. This study analyses the receptors mediating the effects of bradykinin (BK) and analogues on neurogenic twitch contractions of the mouse isolated vas deferens evoked, in the presence of captopril (3 microM), by electrical field stimulation with trains of 4 rectangular 0.5 ms pulses of supramaximal strength, delivered at a frequency of 10 Hz every 20 s. 2. BK (0.1-300 nM) induced a graded potentiation of twitches, with an EC50 (geometric mean and 95% confidence limits) of 4.5 nM (1.7-11.6) and an Emax of 315 +/- 19 mg per 10 mg of wet tissue (n = 6). Similar results were obtained in tissues challenged with Lys-BK, [Hyp3]-BK, Met,Lys-BK and the selective B2 receptor agonist [Tyr(Me)8]-BK (0.1-300 nM). 3. The selective B2 receptor antagonists, Hoe 140 (1-10 nM) and NPC 17731 (3-30 nM), caused graded rightward shifts of the curve to BK-induced twitch potentiation, yielding apparent pA2 values of 9.65 +/- 0.09 and 9.08 +/- 0.13, respectively, and Schild plot slopes not different from 1. Both antagonists (100 nM) failed to modify similar twitch potentiations induced by substance P (3 nM) or endothelin-1 (1 nM). Preincubation with the selective B1 receptor antagonist, [Leu8,des-Arg9]-BK (1 microM), increased the potentiating effect of BK on twitches at 30-300 nM. 4. In contrast to BK, the selective B1 receptor agonist, [des-Arg9]-BK (0.3-1000 nM) reduced the amplitude of twitches in a graded fashion, with an IC50 of 13.7 nM (10.4-16.1) and an Imax of 175 +/- 11 mg (n = 4). The twitch depression induced by [des-Arg9]-BK (300 nM) was not affected by Hoe140 (30nM) or NPC 17731 (100nM), but was abolished by the selective B1 receptor antagonist,[Leu8,des-Arg9]-BK (1 microM), which did not modify the twitch inhibitory effect of clonidine (1 nM) or morphine (300 nM).5. In non-stimulated preparations, BK (100 nM) also potentiated, in a Hoe 140-sensitive (10 nM)manner, the contractions induced by ATP (100 microM), but not by noradrenaline (10 microM), whereas[des-Arg9]-BK (300 n

Modularity of logarithmic parafermion vertex algebras

NASA Astrophysics Data System (ADS)

Auger, Jean; Creutzig, Thomas; Ridout, David

2018-05-01

The parafermionic cosets Ck = {Com} ( H , Lk(sl2) ) are studied for negative admissible levels k, as are certain infinite-order simple current extensions Bk of Ck . Under the assumption that the tensor theory considerations of Huang, Lepowsky and Zhang apply to Ck , irreducible Ck - and Bk -modules are obtained from those of Lk(sl2) . Assuming the validity of a certain Verlinde-type formula likewise gives the Grothendieck fusion rules of these irreducible modules. Notably, there are only finitely many irreducible Bk -modules. The irreducible Ck - and Bk -characters are computed and the latter are shown, when supplemented by pseudotraces, to carry a finite-dimensional representation of the modular group. The natural conjecture then is that the Bk are C_2 -cofinite vertex operator algebras.

Bradykinin activates a cross-signaling pathway between sensory and adrenergic nerve endings in the heart: a novel mechanism of ischemic norepinephrine release?

PubMed

Seyedi, N; Maruyama, R; Levi, R

1999-08-01

We had shown that bradykinin (BK) generated by cardiac sympathetic nerve endings (i.e., synaptosomes) promotes exocytotic norepinephrine (NE) release in an autocrine mode. Because the synaptosomal preparation may include sensory C-fiber endings, which BK is known to stimulate, sensory nerves could contribute to the proadrenergic effects of BK in the heart. We report that BK is a potent releaser of NE from guinea pig heart synaptosomes (EC(50) approximately 20 nM), an effect mediated by B(2) receptors, and almost completely abolished by prior C-fiber destruction or blockade of calcitonin gene-related peptide and neurokinin-1 receptors. C-fiber destruction also greatly decreased BK-induced NE release from the intact heart, whereas tyramine-induced NE release was unaffected. Furthermore, C-fiber stimulation with capsaicin and activation of calcitonin gene-related peptide and neurokinin-1 receptors initiated NE release from cardiac synaptosomes, indicating that stimulation of sensory neurons in turn activates sympathetic nerve terminals. Thus, BK is likely to release NE in the heart in part by first liberating calcitonin gene-related peptide and Substance P from sensory nerve endings; these neuropeptides then stimulate specific receptors on sympathetic terminals. This action of BK is positively modulated by cyclooxygenase products, attenuated by activation of histamine H(3) receptors, and potentiated at a lower pH. The NE-releasing action of BK is likely to be enhanced in myocardial ischemia, when protons accumulate, C fibers become activated, and the production of prostaglandins and BK increases. Because NE is a major arrhythmogenic agent, the activation of this interneuronal signaling system between sensory and adrenergic neurons may contribute to ischemic dysrhythmias and sudden cardiac death.

Cathepsin K: a cysteine protease with unique kinin-degrading properties

PubMed Central

2004-01-01

Taking into account a previous report of an unidentified enzyme from macrophages acting as a kininase, the ability of cysteine proteases to degrade kinins has been investigated. Wild-type fibroblast lysates from mice, by contrast with cathepsin K-deficient lysates, hydrolysed BK (bradykinin), and released two metabolites, BK-(1–4) and BK-(5–9). Cathepsin K, but not cathepsins B, H, L and S, cleaved kinins at the Gly4–Phe5 bond and the bradykinin-mimicking substrate Abz (o-aminobenzoic acid)-RPPGFSPFR-3-NO2-Tyr (3-nitrotyrosine) more efficiently (pH 6.0: kcat/Km=12500 mM−1·s−1; pH 7.4: kcat/Km=6930 mM−1·s−1) than angiotensin-converting enzyme hydrolysed BK. Conversely Abz-RPPGFSPFR-3-NO2-Tyr was not cleaved by the Y67L (Tyr67→Leu)/L205A (Leu205→Ala) cathepsin K mutant, indicating that kinin degradation mostly depends on the S2 substrate specificity. Kininase activity was further evaluated on bronchial smooth muscles. BK, but not its metabolites BK(1-4) and BK(5-9), induced a dose-dependent contraction, which was abolished by Hoe140, a B2-type receptor antagonist. Cathepsin K impaired BK-dependent contraction of normal and chronic hypoxic rats, whereas cathepsins B and L did not. Taking together vasoactive properties of kinins and the potency of cathepsin K to modulate BK-dependent contraction of smooth muscles, the present data support the notion that cathepsin K may act as a kininase, a unique property among mammalian cysteine proteases. PMID:15265002

The release and vascular action of bradykinin in the isolated perfused bovine udder

PubMed Central

Zeitlin, I J; Eshraghi, H R

2002-01-01

It has been postulated that the mammary kinin system may play a role in modulating mammary blood flow. Until the present study, the local release of bradykinin (BK) or other kinin system constituents into the mammary vasculature had not been reported and there were also conflicting findings on the action of BK on udder vasculature. Udders were removed from healthy lactating cows at slaughter. Pairs of ipsilateral quarters were perfused with Tyrode solution through the external pudendalis artery and drained via the cranial superficial epigastric vein. Mammary secretion was collected through teat cannulae. The perfusion pressure was linearly related to perfusate flux between 60 and 210 ml min−1 and the flow rate was adjusted (110-150 ml min−1) to give a basal pressure of 85 mmHg. PO2, PCO2 and pH in the venous effluent perfusate stabilised at 157 ± 10 mmHg, 50.1 ± 2.4 mmHg and 7.1 ± 0.03, respectively. The venous effluent contained immunoreactive BK and BK precursor, tissue kallikrein activity, and bradykinin-destroying enzyme. The concentration of BK stabilised at 378 ± 48 pg (ml perfusate)−1, that of trypsin-activated BK precursor was 679 ± 59 pg BK equivalents ml−1 and that of tissue kallikrein, measured as cleavage of d-Val.Leu.Arg-p-nitroanilide (d-Val.Leu.Arg-pNA), was 5.5 ± 1.7 nmol p-NA h−1 ml−1. Arterial infusion of phenylephrine (0.49-490 μM) produced increases in perfusion pressure (vasoconstriction). Acetylcholine (ACh) (0.55-55 μM) and BK (0.1-10 μM) produced only vasodilatation. BK (EC50 = 1.00±0.04 μM) was a more potent vasodilator than ACh (EC50 = 9.57±0.49 μM). The basal BK concentration was 250 times below the threshold for vasoactivity. The udder produced a milk-like secretion, which was dependent on perfusate flow and contained a concentration of BK which remained unchanged from 60 to 180 min of perfusion (231 ± 31 pg ml−1) unlike that in the venous effluent which doubled between 60 and 120 min. Thus, in addition to its

Maize Brittle stalk2 encodes a COBRA-like protein expressed in early organ development but required for tissue flexibility at maturity.

PubMed

Sindhu, Anoop; Langewisch, Tiffany; Olek, Anna; Multani, Dilbag S; McCann, Maureen C; Vermerris, Wilfred; Carpita, Nicholas C; Johal, Gurmukh

2007-12-01

The maize (Zea mays) brittle stalk2 (bk2) is a recessive mutant, the aerial parts of which are easily broken. The bk2 phenotype is developmentally regulated and appears 4 weeks after planting, at about the fifth-leaf stage. Before this time, mutants are indistinguishable from wild-type siblings. Afterward, all organs of the bk2 mutants turn brittle, even the preexisting ones, and they remain brittle throughout the life of the plant. Leaf tension assays and bend tests of the internodes show that the brittle phenotype does not result from loss of tensile strength but from loss in flexibility that causes the tissues to snap instead of bend. The Bk2 gene was cloned by a combination of transposon tagging and a candidate gene approach and found to encode a COBRA-like protein similar to rice (Oryza sativa) BC1 and Arabidopsis (Arabidopsis thaliana) COBRA-LIKE4. The outer periphery of the stalk has fewer vascular bundles, and the sclerids underlying the epidermis possess thinner secondary walls. Relative cellulose content is not strictly correlated with the brittle phenotype. Cellulose content in mature zones of bk2 mature stems is lowered by 40% but is about the same as wild type in developing stems. Although relative cellulose content is lowered in leaves after the onset of the brittle phenotype, total wall mass as a proportion of dry mass is either unchanged or slightly increased, indicating a compensatory increase in noncellulosic carbohydrate mass. Fourier transform infrared spectra indicated an increase in phenolic ester content in the walls of bk2 leaves and stems. Total content of lignin is unaffected in bk2 juvenile leaves before or after appearance of the brittle phenotype, but bk2 mature and developing stems are markedly enriched in lignin compared to wild-type stems. Despite increased lignin in bk2 stems, loss of staining with phloroglucinol and ultraviolet autofluorescence is observed in vascular bundles and sclerid layers. Consistent with the infrared

Maize Brittle stalk2 Encodes a COBRA-Like Protein Expressed in Early Organ Development But Required for Tissue Flexibility at Maturity1[C][OA

PubMed Central

Sindhu, Anoop; Langewisch, Tiffany; Olek, Anna; Multani, Dilbag S.; McCann, Maureen C.; Vermerris, Wilfred; Carpita, Nicholas C.; Johal, Gurmukh

2007-01-01

The maize (Zea mays) brittle stalk2 (bk2) is a recessive mutant, the aerial parts of which are easily broken. The bk2 phenotype is developmentally regulated and appears 4 weeks after planting, at about the fifth-leaf stage. Before this time, mutants are indistinguishable from wild-type siblings. Afterward, all organs of the bk2 mutants turn brittle, even the preexisting ones, and they remain brittle throughout the life of the plant. Leaf tension assays and bend tests of the internodes show that the brittle phenotype does not result from loss of tensile strength but from loss in flexibility that causes the tissues to snap instead of bend. The Bk2 gene was cloned by a combination of transposon tagging and a candidate gene approach and found to encode a COBRA-like protein similar to rice (Oryza sativa) BC1 and Arabidopsis (Arabidopsis thaliana) COBRA-LIKE4. The outer periphery of the stalk has fewer vascular bundles, and the sclerids underlying the epidermis possess thinner secondary walls. Relative cellulose content is not strictly correlated with the brittle phenotype. Cellulose content in mature zones of bk2 mature stems is lowered by 40% but is about the same as wild type in developing stems. Although relative cellulose content is lowered in leaves after the onset of the brittle phenotype, total wall mass as a proportion of dry mass is either unchanged or slightly increased, indicating a compensatory increase in noncellulosic carbohydrate mass. Fourier transform infrared spectra indicated an increase in phenolic ester content in the walls of bk2 leaves and stems. Total content of lignin is unaffected in bk2 juvenile leaves before or after appearance of the brittle phenotype, but bk2 mature and developing stems are markedly enriched in lignin compared to wild-type stems. Despite increased lignin in bk2 stems, loss of staining with phloroglucinol and ultraviolet autofluorescence is observed in vascular bundles and sclerid layers. Consistent with the infrared

Attenuation of Persistent Experimental Pancreatitis Pain by a Bradykinin B2 Receptor Antagonist

PubMed Central

Chen, Qingmin; Vera-Portocarrero, Louis P.; Ossipov, Michael H.; Vardanyan, Marina; Lai, Josephine; Porreca, Frank

2017-01-01

Objective The role of bradykinin (BK) receptors in activating and sensitizing peripheral nociceptors is well known. Recently, we showed that spinal dynorphin was pronociceptive through direct or indirect BK receptor activation. Here, we explored the potential role of BK receptors in pain associated with persistent pancreatitis in rats. Methods Experimental pancreatitis and abdominal hypersensitivity were induced by intravenous administrations of dibutyltin dichloride (DBTC). [des-Arg9-Leu8]BK (B1 antagonist) and HOE 140 (B2 antagonist) were given by intraperitoneal or intrathecal injection. Dynorphin antiserum was given intrathecally. Reverse transcription–polymerase chain reaction was used to detect spinal mRNA for BK receptors. Results Dibutyltin dichloride–induced pancreatitis upregulated B1 and B2 mRNA in the thoracic dorsal root ganglion and B2, but not B1, in the pancreas. No changes in spinal B1 or B2 mRNA were observed. Intraperitoneal or intrathecal administration of HOE 140 dose dependently abolished DBTC-induced abdominal hypersensitivity, whereas [des-Arg9-Leu8]BK was without effect by either route of administration. Antiserum to dynorphin (intrathecal) abolished DBTC-induced hypersensitivity. Conclusions These results suggest that blockade of peripheral or spinal BK B2 receptors may be an effective approach for diminishing pain associated with pancreatitis. Moreover, it is suggested that spinal dynorphin may maintain pancreatitis pain through direct or indirect activation of BK B2 receptors in the spinal cord. PMID:20531238

BK Polyomavirus Replication in Renal Tubular Epithelial Cells Is Inhibited by Sirolimus, but Activated by Tacrolimus Through a Pathway Involving FKBP-12.

PubMed

Hirsch, H H; Yakhontova, K; Lu, M; Manzetti, J

2016-03-01

BK polyomavirus (BKPyV) replication causes nephropathy and premature kidney transplant failure. Insufficient BKPyV-specific T cell control is regarded as a key mechanism, but direct effects of immunosuppressive drugs on BKPyV replication might play an additional role. We compared the effects of mammalian target of rapamycin (mTOR)- and calcineurin-inhibitors on BKPyV replication in primary human renal tubular epithelial cells. Sirolimus impaired BKPyV replication with a 90% inhibitory concentration of 4 ng/mL by interfering with mTOR-SP6-kinase activation. Sirolimus inhibition was rapid and effective up to 24 h postinfection during viral early gene expression, but not thereafter, during viral late gene expression. The mTORC-1 kinase inhibitor torin-1 showed a similar inhibition profile, supporting the notion that early steps of BKPyV replication depend on mTOR activity. Cyclosporine A also inhibited BKPyV replication, while tacrolimus activated BKPyV replication and reversed sirolimus inhibition. FK binding protein 12kda (FKBP-12) siRNA knockdown abrogated sirolimus inhibition and increased BKPyV replication similar to adding tacrolimus. Thus, sirolimus and tacrolimus exert opposite effects on BKPyV replication in renal tubular epithelial cells by a mechanism involving FKBP-12 as common target. Immunosuppressive drugs may therefore contribute directly to the risk of BKPyV replication and nephropathy besides suppressing T cell functions. The data provide rationales for clinical trials aiming at reducing the risk of BKPyV replication and disease in kidney transplantation. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.

The Polyomavirus BK Large T-Antigen-Derived Peptide Elicits an HLA-DR Promiscuous and Polyfunctional CD4+ T-Cell Response▿

PubMed Central

Ramaswami, Bala; Popescu, Iulia; Macedo, Camila; Luo, Chunqing; Shapiro, Ron; Metes, Diana; Chalasani, Geetha; Randhawa, Parmjeet S.

2011-01-01

BK virus (BKV) nephropathy and hemorrhagic cystitis are increasingly recognized causes of disease in renal and hematopoietic stem cell transplant recipients, respectively. Functional characterization of the immune response to BKV is important for clinical diagnosis, prognosis, and vaccine design. A peptide mix (PepMix) and overlapping (OPP) or random (RPP) peptide pools derived from BKV large T antigen (LTA) were used to restimulate 14-day-expanded peripheral blood mononuclear cells (PBMC) from 27 healthy control subjects in gamma interferon (IFN-γ)-specific enzyme-linked immunospot (ELISPOT) assays. A T-cell response to LTA PepMix was detected in 15/27 subjects. A response was frequently observed with peptides derived from the helicase domain (9/15 subjects), while the DNA binding and host range domains were immunologically inert (0/15 subjects). For all nine subjects who responded to LTA peptide pools, the immune response could be explained largely by a 15-mer peptide designated P313. P313-specific CD4+ T-cell clones demonstrated (i) stringent LTA peptide specificity; (ii) promiscuous recognition in the context of HLA-DR alleles; (iii) cross recognition of homologous peptides from the polyomavirus simian virus 40 (SV40); (iv) an effector memory phenotype, CD107a expression, and intracellular production of IFN-γ and tumor necrosis factor alpha (TNF-α); (v) cytotoxic activity in a chromium release assay; and (vi) the ability to directly present cognate antigen to autologous T cells. In conclusion, T-cell-mediated immunity to BKV in healthy subjects is associated with a polyfunctional population of CD4+ T cells with dual T-helper and T-cytotoxic properties. HLA class II promiscuity in antigen presentation makes the targeted LTA peptide sequence a suitable candidate for inclusion in immunotherapy protocols. PMID:21367979

The polyomavirus BK large T-antigen-derived peptide elicits an HLA-DR promiscuous and polyfunctional CD4+ T-cell response.

PubMed

Ramaswami, Bala; Popescu, Iulia; Macedo, Camila; Luo, Chunqing; Shapiro, Ron; Metes, Diana; Chalasani, Geetha; Randhawa, Parmjeet S

2011-05-01

BK virus (BKV) nephropathy and hemorrhagic cystitis are increasingly recognized causes of disease in renal and hematopoietic stem cell transplant recipients, respectively. Functional characterization of the immune response to BKV is important for clinical diagnosis, prognosis, and vaccine design. A peptide mix (PepMix) and overlapping (OPP) or random (RPP) peptide pools derived from BKV large T antigen (LTA) were used to restimulate 14-day-expanded peripheral blood mononuclear cells (PBMC) from 27 healthy control subjects in gamma interferon (IFN-γ)-specific enzyme-linked immunospot (ELISPOT) assays. A T-cell response to LTA PepMix was detected in 15/27 subjects. A response was frequently observed with peptides derived from the helicase domain (9/15 subjects), while the DNA binding and host range domains were immunologically inert (0/15 subjects). For all nine subjects who responded to LTA peptide pools, the immune response could be explained largely by a 15-mer peptide designated P313. P313-specific CD4(+) T-cell clones demonstrated (i) stringent LTA peptide specificity; (ii) promiscuous recognition in the context of HLA-DR alleles; (iii) cross recognition of homologous peptides from the polyomavirus simian virus 40 (SV40); (iv) an effector memory phenotype, CD107a expression, and intracellular production of IFN-γ and tumor necrosis factor alpha (TNF-α); (v) cytotoxic activity in a chromium release assay; and (vi) the ability to directly present cognate antigen to autologous T cells. In conclusion, T-cell-mediated immunity to BKV in healthy subjects is associated with a polyfunctional population of CD4(+) T cells with dual T-helper and T-cytotoxic properties. HLA class II promiscuity in antigen presentation makes the targeted LTA peptide sequence a suitable candidate for inclusion in immunotherapy protocols.

Bradykinin induced a positive chronotropic effect via stimulation of T- and L-type calcium currents in heart cells.

PubMed

El-Bizri, Nesrine; Bkaily, Ghassan; Wang, Shimin; Jacques, Danielle; Regoli, Domenico; D'Orléans-Juste, Pedro; Sukarieh, Rami

2003-03-01

Using Fluo-3 calcium dye confocal microscopy and spontaneously contracting embryonic chick heart cells, bradykinin (10(-10) M) was found to induce positive chronotropic effects by increasing the frequency of the transient increase of cytosolic and nuclear free Ca2+. Pretreatment of the cells with either B1 or B2 receptor antagonists (R126 and R817, respectively) completely prevented bradykinin (BK) induced positive chronotropic effects on spontaneously contracting single heart cells. Using the whole-cell voltage clamp technique and ionic substitution to separate the different ionic current species, our results showed that BK (10(-6) M) had no effect on fast Na+ inward current and delayed outward potassium current. However, both L- and T-type Ca2+ currents were found to be increased by BK in a dose-dependent manner (10(-10)-10(-7) M). The effects of BK on T- and L-type Ca2+ currents were partially blocked by the B1 receptor antagonist [Leu8]des-Arg9-BK (R592) (10(-7) M) and completely reversed by the B2 receptor antagonist D-Arg[Hyp3,D-Phe7,Leu8]BK (R-588) (10(-7) M) or pretreatment with pertussis toxin (PTX). These results demonstrate that BK induced a positive chronotropic effect via stimulation of T- and L-type Ca2+ currents in heart cells mainly via stimulation of B2 receptor coupled to PTX-sensitive G-proteins. The increase of both types of Ca2+ current by BK in heart cells may explain the positive inotropic and chronotropic effects of this hormone.

Simultaneous immunostaining with anti-S100P and anti-SV40 antibodies revealed the origin of BK virus-infected decoy cells in voided urine samples.

PubMed

Ariyasu, S; Yanai, H; Sato, M; Shinno, Y; Taniguchi, K; Yamadori, I; Miki, Y; Sato, Y; Yoshino, T; Takahashi, K

2015-08-01

Methods for determining the origin of BK virus (BKV)-infected cells (decoy cells) in clinical urine samples have not been established although they could enhance the diagnosis of BKV infection in immunocompromised patients. We performed simultaneous immunostaining with anti-S100P (a urothelial marker) and anti-SV40 antibodies in 66 clinical urine samples exhibiting SV40 positivity and a decoy-cell appearance on Papanicolaou staining. The clinical voided urine samples included seven cases of renal transplantation, 47 cases of cancer therapy and 12 cases of non-neoplastic disease. SurePath(™) liquid-based cytology was used for the urine samples. BKV-infected cells were categorized as SV40(+)/S100P(+) and SV40 (+)/S100p(-). SV40(+)/S100P(-) cells were found in 55 cases (83.4%); nine cases (13.6%) carried both SV40(+)/S100P(-) and SV40(+)/S100P(+) cells. The former were identified as BKV infection in renal tubules and the latter in both the renal tubules and urothelial epithelia. The remaining two cases (3.0%) had only SV40(+)/S100P(+) cells of urothelial origin. Simultaneous immunostaining with anti-S100P and anti-SV40 is a useful method for determining the origin of BKV-infected cells in clinical urine samples from immunocompromised patients such as renal transplantation recipients. © 2014 John Wiley & Sons Ltd.

Studies on the vascular permeability induced by intrathecal substance P and bradykinin in the rat.

PubMed

Jacques, L; Couture, R

1990-08-02

The effects of substance P (SP), SP fragments, neurokinin A (NKA), neurokinin B (NKB) and selective agonists for neurokinin receptors were assessed on cutaneous vascular permeability after intrathecal (i.t.) administration in rats. Dose-dependent increases in plasma extravasation were observed with the following rank orders of potency ([p-Glu6]SP-(6-11) greater than SP greater than or equal to SP-(4-11) greater than [p-Glu5,MePhe8,Sar9]SP-(5-11) = [p-Glu5]SP-(5-11) greater than SP-(7-11) and SP greater than NKA greater than NKB). The N-terminal fragments SP-(1-4), SP-(1-7) and SP-(1-9) were inactive up to 65 nmol. The NK-1 receptor selective agonists [( beta-Ala4,Sar9,Met(O2)11]SP-(4-11) and [Pro9,Met(O2)11]SP) were more potent than the NK-2 ([Nle10]NKA-(4-10] and NK-3 ([beta-Asp4,MePhe7]NKB-(4-10) and [MePhe7]NKB) receptor-selective agonists. Plasma extravasation was also increased by i.t. bradykinin (BK, 8.1 nmol) while the fragment BK-(1-8), a potent B1-receptor-selective agonist, produced only a slight effect at 81 nmol. When BK was given after prior i.t. administration of 6.1 nmol of [Thi5.8,D-Phe7]BK, an antagonist of BK at the B2-receptor, the increase in vascular permeability was significantly attenuated. The analogue [Leu8]BK-(1-8) (10.3 nmol), an antagonist of BK at the B1-receptor, failed to modify the BK-induced plasma extravasation. Plasma extravasation induced by SP (6.5 nmol) and BK (8.1 nmol) was abolished in cervically vagotomized rats, and significantly reduced in both spinal rats and in capsaicin-treated animals. Conversely, bilateral adrenalectomy (48 h earlier) and intercollicular decerebration (30 min earlier) had no major effect on the response elicited either by SP or BK. The response to SP remained unaffected by methysergide and hexamethonium but was significantly reduced by methylnitrate atropine and diphenhydramine. Indomethacin significantly enhanced the plasma extravasation induced by SP. These results suggest that SP and BK may play a

Thermodynamic functions of Fermi gas with quadruple BCS-type binding potential

NASA Astrophysics Data System (ADS)

Tarasewicz, P.; Maćkowiak, J.

2000-01-01

A gas of spin 1/2 fermions with an interaction V+ W=-2 γ∑ kχ( k) bk* bk+-| Λ| -1g∑ k, k‧ χ( k) χ( k‧) bk* bk* bk‧ b- k‧ , where bk= ak+ ak- and akσ , ak‧ σ‧ satisfy Fermi anticommutation relations, is investigated by the method of Mühlschlegel. W+ V is nonzero only within a thin layer of single-fermion energies around the chemical potential μ and χ( k) denotes the characteristic function of the corresponding range of momenta. Two cases are studied: 1 0γ=0, 2 0γ=0.10025 eV. In the first case, the system exhibits a first-order transition, in the second the transition is second order. The temperature dependence of the system's thermodynamic functions is examined and compared with that of the BCS model.

Methamphetamine Regulation of Firing Activity of Dopamine Neurons

PubMed Central

Lin, Min; Sambo, Danielle

2016-01-01

Methamphetamine (METH) is a substrate for the dopamine transporter that increases extracellular dopamine levels by competing with dopamine uptake and increasing reverse transport of dopamine via the transporter. METH has also been shown to alter the excitability of dopamine neurons. The mechanism of METH regulation of the intrinsic firing behaviors of dopamine neurons is less understood. Here we identified an unexpected and unique property of METH on the regulation of firing activity of mouse dopamine neurons. METH produced a transient augmentation of spontaneous spike activity of midbrain dopamine neurons that was followed by a progressive reduction of spontaneous spike activity. Inspection of action potential morphology revealed that METH increased the half-width and produced larger coefficients of variation of the interspike interval, suggesting that METH exposure affected the activity of voltage-dependent potassium channels in these neurons. Since METH has been shown to affect Ca2+ homeostasis, the unexpected findings that METH broadened the action potential and decreased the amplitude of afterhyperpolarization led us to ask whether METH alters the activity of Ca2+-activated potassium (BK) channels. First, we identified BK channels in dopamine neurons by their voltage dependence and their response to a BK channel blocker or opener. While METH suppressed the amplitude of BK channel-mediated unitary currents, the BK channel opener NS1619 attenuated the effects of METH on action potential broadening, afterhyperpolarization repression, and spontaneous spike activity reduction. Live-cell total internal reflection fluorescence microscopy, electrophysiology, and biochemical analysis suggest METH exposure decreased the activity of BK channels by decreasing BK-α subunit levels at the plasma membrane. SIGNIFICANCE STATEMENT Methamphetamine (METH) competes with dopamine uptake, increases dopamine efflux via the dopamine transporter, and affects the excitability of

Mechanisms of bradykinin-induced expression of connective tissue growth factor and nephrin in podocytes

PubMed Central

Msallem, J. Abou; Chalhoub, H.; Al-Hariri, M.; Saad, L.; Jaffa, M. A.; Ziyadeh, F. N.

2015-01-01

Diabetic nephropathy (DN) is the main cause of morbidity and mortality in diabetes and is characterized by mesangial matrix deposition and podocytopathy, including podocyte loss. The risk factors and mechanisms involved in the pathogenesis of DN are still not completely defined. In the present study, we aimed to understand the cellular mechanisms through which activation of B2 kinin receptors contribute to the initiation and progression of DN. Stimulation of cultured rat podocytes with bradykinin (BK) resulted in a significant increase in ROS generation, and this was associated with a significant increase in NADPH oxidase (NOX)1 and NOX4 protein and mRNA levels. BK stimulation also resulted in a signicant increase in the phosphorylation of ERK1/2 and Akt, and this effect was inhibited in the presence of NOX1 and Nox4 small interfering (si)RNA. Furthermore, podocytes stimulated with BK resulted in a significant increase in protein and mRNA levels of connective tissue growth factor (CTGF) and, at the same time, a significant decrease in protein and mRNA levels of nephrin. siRNA targeted against NOX1 and NOX4 significantly inhibited the BK-induced increase in CTGF. Nephrin expression was increased in response to BK in the presence of NOX1 and NOX4 siRNA, thus implicating a role for NOXs in modulating the BK response in podocytes. Moreover, nephrin expression in response to BK was also significantly increased in the presence of siRNA targeted against CTGF. These findings provide novel aspects of BK signal transduction pathways in pathogenesis of DN and identify novel targets for interventional strategies. PMID:26447218

Activation of muscarinic M3 receptors inhibits large-conductance voltage- and Ca2+-activated K+ channels in rat urinary bladder smooth muscle cells

PubMed Central

Parajuli, Shankar P.

2013-01-01

Large conductance voltage- and Ca2+-activated K+ (BK) channels are key regulators of detrusor smooth muscle (DSM) contraction and relaxation during urine voiding and storage. Here, we explored whether BK channels are regulated by muscarinic receptors (M-Rs) in native freshly isolated rat DSM cells under physiological conditions using the perforated whole cell patch-clamp technique and pharmacological inhibitors. M-R activation with carbachol (1 μM) initially evoked large transient outward BK currents, followed by inhibition of the spontaneous transient outward BK currents (STBKCs) in DSM cells. Carbachol (1 μM) also inhibited the amplitude and frequency of spontaneous transient hyperpolarizations (STHs) and depolarized the DSM cell membrane potential. Selective inhibition of the muscarinic M3 receptors (M3-Rs) with 4-diphenylacetoxy-N-methylpiperidine (4-DAMP; 0.1 μM), but not muscarinic M2 receptors with methoctramine (1 μM), blocked the carbachol inhibitory effects on STBKCs. Furthermore, blocking the inositol 1,4,5-triphosphate (IP3) receptors with xestospongin-C (1 μM) inhibited the carbachol-induced large transient outward BK currents without affecting carbachol inhibitory effects on STBKCs. Upon pharmacological inhibition of all known cellular sources of Ca2+ for BK channel activation, carbachol (1 μM) did not affect the voltage-step-induced steady-state BK currents, suggesting that the muscarinic effects in DSM cells are mediated by mobilization of intracellular Ca2+. In conclusion, our findings provide strong evidence that activation of M3-Rs leads to inhibition of the STBKCs, STHs, and depolarization of DSM cells. Collectively, the data suggest the existence of functional interactions between BK channels and M3-Rs at a cellular level in DSM. PMID:23703523

A Prospective Study on the Predictive Value of Plasma BK Virus-DNA Load for Hemorrhagic Cystitis in Pediatric Patients After Stem Cell Transplantation.

PubMed

Cesaro, Simone; Tridello, Gloria; Pillon, Marta; Calore, Elisabetta; Abate, Davide; Tumino, Manuela; Carucci, Nicolina; Varotto, Stefania; Cannata, Elisa; Pegoraro, Anna; Barzon, Luisa; Palù, Giorgio; Messina, Chiara

2015-06-01

In hematopoietic stem cell transplantation (HSCT), late hemorrhagic cystitis (HC) has been associated with BK virus (BKV) infection. We assessed the value of plasma BKV load in predicting HC. Plasma and urine BKV-DNA load were assessed prospectively in 107 pediatric patients. Twenty patients developed grade II and III HC, with 100-day cumulative incidence of 18.8%. At diagnosis of HC, the median load of BKV DNA was 2.3 × 10(3) copies/mL. A plasma BKV-DNA load of 10(3) copies/mL had a sensitivity of 100% and a specificity of 86% with a negative predictive value (NPV) of 100% and a positive predictive value (PPV) of 39% for HC. A urine BKV-DNA load of >10(7) copies/mL had a sensitivity of 86% and a specificity of 60% with a NPV of 98% and a PPV of 14% for HC. A BKV load of 10(3) copies/mL on plasma was significantly associated with HC in multivariate analysis (hazard ratio [HR], 6.1; P = .0006). Patients with HC had a significantly higher risk of mortality than patients who did not have HC (HR, 2.6; P = .018). The above values were used to monitor plasma BKV-DNA load, and they provided a better prediction of patients at risk of HC than urine BKV-DNA load. © The Author 2014. Published by Oxford University Press on behalf of the Pediatric Infectious Diseases Society. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Overexpression of Large-Conductance Calcium-Activated Potassium Channels in Human Glioblastoma Stem-Like Cells and Their Role in Cell Migration.

PubMed

Rosa, Paolo; Sforna, Luigi; Carlomagno, Silvia; Mangino, Giorgio; Miscusi, Massimo; Pessia, Mauro; Franciolini, Fabio; Calogero, Antonella; Catacuzzeno, Luigi

2017-09-01

Glioblastomas (GBMs) are brain tumors characterized by diffuse invasion of cancer cells into the healthy brain parenchyma, and establishment of secondary foci. GBM cells abundantly express large-conductance, calcium-activated potassium (BK) channels that are thought to promote cell invasion. Recent evidence suggests that the GBM high invasive potential mainly originates from a pool of stem-like cells, but the expression and function of BK channels in this cell subpopulation have not been studied. We investigated the expression of BK channels in GBM stem-like cells using electrophysiological and immunochemical techniques, and assessed their involvement in the migratory process of this important cell subpopulation. In U87-MG cells, BK channel expression and function were markedly upregulated by growth conditions that enriched the culture in GBM stem-like cells (U87-NS). Cytofluorimetric analysis further confirmed the appearance of a cell subpopulation that co-expressed high levels of BK channels and CD133, as well as other stem cell markers. A similar association was also found in cells derived from freshly resected GBM biopsies. Finally, transwell migration tests showed that U87-NS cells migration was much more sensitive to BK channel block than U87-MG cells. Our data show that BK channels are highly expressed in GBM stem-like cells, and participate to their high migratory activity. J. Cell. Physiol. 232: 2478-2488, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

NADPH oxidase 2-derived reactive oxygen species signal contributes to bradykinin-induced matrix metalloproteinase-9 expression and cell migration in brain astrocytes

PubMed Central

2012-01-01

Background Matrix metalloproteinase-9 (MMP-9) plays a crucial role in pathological processes of brain inflammation, injury, and neurodegeneration. Moreover, bradykinin (BK) induces the expression of several inflammatory proteins in brain astrocytes. Recent studies have suggested that increased oxidative stress is implicated in the brain inflammation and injury. However, whether BK induced MMP-9 expression mediated through oxidative stress remains virtually unknown. Herein we investigated the role of redox signals in BK-induced MMP-9 expression in rat brain astrocytes (RBA-1 cells). Results In the study, we first demonstrated that reactive oxygen species (ROS) plays a crucial role in BK-induced MMP-9 expression in cultured brain astrocytes (in vitro) and animal brain tissue (in vivo) models. Next, BK-induced MMP-9 expression is mediated through a Ca2+-mediated PKC-α linking to p47phox/NADPH oxidase 2 (Nox2)/ROS signaling pathway. Nox2-dependent ROS generation led to activation and up-regulation of the downstream transcriptional factor AP-1 (i.e. c-Fos and c-Jun), which bound to MMP-9 promoter region, and thereby turned on transcription of MMP-9 gene. Functionally, BK-induced MMP-9 expression enhanced astrocytic migration. Conclusions These results demonstrated that in RBA-1 cells, activation of AP-1 (c-Fos/c-Jun) by the PKC-α-mediated Nox2/ROS signals is essential for up-regulation of MMP-9 and cell migration enhanced by BK. PMID:23176293

Chelation and stabilization of berkelium in oxidation state +IV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deblonde, Gauthier J. -P.; Sturzbecher-Hoehne, Manuel; Rupert, Peter B.

Berkelium (Bk) has been predicted to be the only transplutonium element able to exhibit both +III and +IV oxidation states in solution, but evidence of a stable oxidized Bk chelate has so far remained elusive. Here, in this work, we describe the stabilization of the heaviest 4+ ion of the periodic table, under mild aqueous conditions, using a siderophore derivative. The resulting Bk(IV) complex exhibits luminescence via sensitization through an intramolecular antenna effect. This neutral Bk(IV) coordination compound is not sequestered by the protein siderocalin - a mammalian metal transporter - in contrast to the negatively charged species obtained withmore » neighbouring trivalent actinides americium, curium and californium (Cf). The corresponding Cf(III)-ligand-protein ternary adduct was characterized by X-ray diffraction analysis. Finally, combined with theoretical predictions, these data add significant insight to the field of transplutonium chemistry, and may lead to innovative Bk separation and purification processes.« less

Chelation and stabilization of berkelium in oxidation state +IV

DOE PAGES

Deblonde, Gauthier J. -P.; Sturzbecher-Hoehne, Manuel; Rupert, Peter B.; ...

2017-04-10

Berkelium (Bk) has been predicted to be the only transplutonium element able to exhibit both +III and +IV oxidation states in solution, but evidence of a stable oxidized Bk chelate has so far remained elusive. Here, in this work, we describe the stabilization of the heaviest 4+ ion of the periodic table, under mild aqueous conditions, using a siderophore derivative. The resulting Bk(IV) complex exhibits luminescence via sensitization through an intramolecular antenna effect. This neutral Bk(IV) coordination compound is not sequestered by the protein siderocalin - a mammalian metal transporter - in contrast to the negatively charged species obtained withmore » neighbouring trivalent actinides americium, curium and californium (Cf). The corresponding Cf(III)-ligand-protein ternary adduct was characterized by X-ray diffraction analysis. Finally, combined with theoretical predictions, these data add significant insight to the field of transplutonium chemistry, and may lead to innovative Bk separation and purification processes.« less

Mechanisms of acetylcholine- and bradykinin-induced preconditioning.

PubMed

Critz, Stuart D; Cohen, Michael V; Downey, James M

2005-01-01

Acetylcholine (ACh) and bradykinin (BK) are potent pharmacological agents which mimic ischemic preconditioning (IPC) enabling hearts to resist infarction during a subsequent period of ischemia. The cardioprotective pathways activated by BK but not ACh may also protect when activated at reperfusion. ACh and BK stimulate Gi/o-linked receptors and ultimately mediate protection by opening mitochondrial ATP-sensitive potassium channels with the generation of reactive oxygen species that act as second messengers to activate protein kinase C (PKC). There appear to be key differences, however, in the pathways prior to potassium channel opening for these two receptors. This review aims to summarize what is currently known about pharmacological preconditioning by ACh and BK with an emphasis on differences that are seen in the signal transduction cascades. Understanding the cellular basis of protection by ACh and BK is a critical step towards developing pharmacological agents that will prevent infarction during ischemia resulting from coronary occlusion or heart attack.

Codes over infinite family of rings : Equivalence and invariant ring

NASA Astrophysics Data System (ADS)

Irwansyah, Muchtadi-Alamsyah, Intan; Muchlis, Ahmad; Barra, Aleams; Suprijanto, Djoko

2016-02-01

In this paper, we study codes over the ring Bk=𝔽pr[v1,…,vk]/(vi2=vi,∀i =1 ,…,k ) . For instance, we focus on two topics, i.e. characterization of the equivalent condition between two codes over Bk using a Gray map into codes over finite field 𝔽pr, and finding generators for invariant ring of Hamming weight enumerator for Euclidean self-dual codes over Bk.

DiBAC4(3) hits a “sweet spot” for the activation of arterial large-conductance Ca2+-activated potassium channels independently of the β1-subunit

PubMed Central

Scornik, Fabiana S.; Bucciero, Ronald S.; Wu, Yuesheng; Selga, Elisabet; Bosch Calero, Cristina; Brugada, Ramon

2013-01-01

The voltage-sensitive dye bis-(1,3-dibutylbarbituric acid)trimethine oxonol [DiBAC4(3)] has been reported as a novel large-conductance Ca2+-activated K+ (BK) channel activator with selectivity for its β1- or β4-subunits. In arterial smooth muscle, BK channels are formed by a pore-forming α-subunit and a smooth muscle-abundant regulatory β1-subunit. This tissue specificity has driven extensive pharmacological research aimed at regulating arterial tone. Using animals with a disruption of the gene for the β1-subunit, we explored the effects of DiBAC4(3) in native channels from arterial smooth muscle. We tested the hypothesis that, in native BK channels, activation by DiBAC4(3) relies mostly on its α-subunit. We studied BK channels from wild-type and transgenic β1-knockout mice in excised patches. BK channels from brain arteries, with or without the β1-subunit, were similarly activated by DiBAC4(3). In addition, we found that saturating concentrations of DiBAC4(3) (∼30 μM) promote an unprecedented persistent activation of the channel that negatively shifts its voltage dependence by as much as −300 mV. This “sweet spot” for persistent activation is independent of Ca2+ and/or the β1–4-subunits and is fully achieved when DiBAC4(3) is applied to the intracellular side of the channel. Arterial BK channel response to DiBAC4(3) varies across species and/or vascular beds. DiBAC4(3) unique effects can reveal details of BK channel gating mechanisms and help in the rational design of BK channel activators. PMID:23542916

Local calcium signalling is mediated by mechanosensitive ion channels in mesenchymal stem cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chubinskiy-Nadezhdin, Vladislav I., E-mail: vchubinskiy@gmail.com; Vasileva, Valeria Y.; Pugovkina, Natalia A.

Mechanical forces are implicated in key physiological processes in stem cells, including proliferation, differentiation and lineage switching. To date, there is an evident lack of understanding of how external mechanical cues are coupled with calcium signalling in stem cells. Mechanical reactions are of particular interest in adult mesenchymal stem cells because of their promising potential for use in tissue remodelling and clinical therapy. Here, single channel patch-clamp technique was employed to search for cation channels involved in mechanosensitivity in mesenchymal endometrial-derived stem cells (hMESCs). Functional expression of native mechanosensitive stretch-activated channels (SACs) and calcium-sensitive potassium channels of different conductances inmore » hMESCs was shown. Single current analysis of stretch-induced channel activity revealed functional coupling of SACs and BK channels in plasma membrane. The combination of cell-attached and inside-out experiments have indicated that highly localized Ca{sup 2+} entry via SACs triggers BK channel activity. At the same time, SK channels are not coupled with SACs despite of high calcium sensitivity as compared to BK. Our data demonstrate novel mechanism controlling BK channel activity in native cells. We conclude that SACs and BK channels are clusterized in functional mechanosensitive domains in the plasma membrane of hMESCs. Co-clustering of ion channels may significantly contribute to mechano-dependent calcium signalling in stem cells. - Highlights: • Stretch-induced channel activity in human mesenchymal stem cells was analyzed. • Functional expression of SACs and Ca{sup 2+}-sensitive BK and SK channels was shown. • Local Ca{sup 2+} influx via stretch-activated channels triggers BK channel activity. • SK channels are not coupled with SACs despite higher sensitivity to [Ca{sup 2+}]{sub i}. • Functional clustering of SACs and BK channels in stem cell membrane is proposed.« less

Brittle stalk 2 encodes a putative glycosylphosphatidylinositol-anchored protein that affects mechanical strength of maize tissues by altering the composition and structure of secondary cell walls.

PubMed

Ching, Ada; Dhugga, Kanwarpal S; Appenzeller, Laura; Meeley, Robert; Bourett, Timothy M; Howard, Richard J; Rafalski, Antoni

2006-10-01

A spontaneous maize mutant, brittle stalk-2 (bk2-ref), exhibits dramatically reduced tissue mechanical strength. Reduction in mechanical strength in the stalk tissue was highly correlated with a reduction in the amount of cellulose and an uneven deposition of secondary cell wall material in the subepidermal and perivascular sclerenchyma fibers. Cell wall accounted for two-thirds of the observed reduction in dry matter content per unit length of the mutant stalk in comparison to the wildtype stalk. Although the cell wall composition was significantly altered in the mutant in comparison to the wildtype stalks, no compensation by lignin and cell wall matrix for reduced cellulose amount was observed. We demonstrate that Bk2 encodes a Cobra-like protein that is homologous to the rice Bc1 protein. In the bk2-ref gene, a 1 kb transposon-like element is inserted in the beginning of the second exon, disrupting the open reading frame. The Bk2 gene was expressed in the stalk, husk, root, and leaf tissues, but not in the embryo, endosperm, pollen, silk, or other tissues with comparatively few or no secondary cell wall containing cells. The highest expression was in the isolated vascular bundles. In agreement with its role in secondary wall formation, the expression pattern of the Bk2 gene was very similar to that of the ZmCesA10, ZmCesA11, and ZmCesA12 genes, which are known to be involved in secondary wall formation. We have isolated an independent Mutator-tagged allele of bk2, referred to as bk2-Mu7, the phenotype of which is similar to that of the spontaneous mutant. Our results demonstrate that mutations in the Bk2 gene affect stalk strength in maize by interfering with the deposition of cellulose in the secondary cell wall in fiber cells.

Cidofovir in the Treatment of BK Virus-Associated Hemorrhagic Cystitis after Allogeneic Hematopoietic Stem Cell Transplantation.

PubMed

Philippe, Michael; Ranchon, Florence; Gilis, Lila; Schwiertz, Vérane; Vantard, Nicolas; Ader, Florence; Labussiere-Wallet, Hélène; Thomas, Xavier; Nicolini, Franck-Emmanuel; Wattel, Eric; Ducastelle-Leprêtre, Sophie; Barraco, Fiorenza; Lebras, Laure; Salles, Gilles; Michallet, Mauricette; Rioufol, Catherine

2016-04-01

After allogeneic hematopoietic stem cell transplantation (HSCT), BK virus-associated hemorrhagic cystitis (BKV-HC) is a common complication. Although supportive measures have been the standard of care for many years, several studies suggested the efficacy of cidofovir. The aim of this study was to assess the safety profile and efficacy of cidofovir. A retrospective study was conducted on all patients treated with cidofovir in our HSCT unit between March 2011 and May 2013. Data for efficacy (partial [PR] or complete response [CR]), prescription (dose, frequency, number of doses, and administration route), and toxicity were collected from published reports and medical files. Renal toxicity was evaluated using creatinine clearance calculated with the Cockcroft and Gault formula. A parallel literature search using PubMed (last search, May 2015) was performed. From March 2011 to June 2013, 27 of 181 patients undergoing allogeneic HSCT in our department received cidofovir for BKV-HC: 24 (88.9%) intravenously, 1 intravesically, and 2 via both routes. Mean dose was 5 mg/kg per administration, for a median of 4 injections (range, 1 to 11), from twice a week to once every 2 weeks. CR was achieved in 22 patients (81.5%), PR in 2, and no response in 2 patients. Eight patients presented renal failure (29.6%): 6 moderate (creatinine clearance < 60 mL/min) and 2 severe (creatinine clearance < 30 mLmin). Mean decrease in creatinine clearance after cidofovir was 27% (35 mL/min; range, 2 to 159). In 3 cases renal insufficiency and hematologic toxicity led to discontinuation of treatment or switch to intravesical instillation. For 3 patients cidofovir dose was reduced because of nephrotoxicity. Thirteen studies have reported on the use of cidofovir for BKV-HC (204 patients) since 2005. Intravenous cidofovir was used for 91.3% of patients, with doses ranging from .5 to 5 mg/kg. The main toxicity reported was renal failure (9% to 50% in 9 studies). Between 60% and 100% of CRs

Fagopyrum esculentum Alters Its Root Exudation after Amaranthus retroflexus Recognition and Suppresses Weed Growth

PubMed Central

Gfeller, Aurélie; Glauser, Gaétan; Etter, Clément; Signarbieux, Constant; Wirth, Judith

2018-01-01

Weed control by crops through growth suppressive root exudates is a promising alternative to herbicides. Buckwheat (Fagopyrum esculentum) is known for its weed suppression and redroot pigweed (Amaranthus retroflexus) control is probably partly due to allelopathic root exudates. This work studies whether other weeds are also suppressed by buckwheat and if the presence of weeds is necessary to induce growth repression. Buckwheat and different weeds were co-cultivated in soil, separating roots by a mesh allowing to study effects due to diffusion. Buckwheat suppressed growth of pigweed, goosefoot and barnyard grass by 53, 42, and 77% respectively without physical root interactions, probably through allelopathic compounds. Root exudates were obtained from sand cultures of buckwheat (BK), pigweed (P), and a buckwheat/pigweed mixed culture (BK-P). BK-P root exudates inhibited pigweed root growth by 49%. Characterization of root exudates by UHPLC-HRMS and principal component analysis revealed that BK and BK-P had a different metabolic profile suggesting that buckwheat changes its root exudation in the presence of pigweed indicating heterospecific recognition. Among the 15 different markers, which were more abundant in BK-P, tryptophan was identified and four others were tentatively identified. Our findings might contribute to the selection of crops with weed suppressive effects. PMID:29445385

Fagopyrum esculentum Alters Its Root Exudation after Amaranthus retroflexus Recognition and Suppresses Weed Growth.

PubMed

Gfeller, Aurélie; Glauser, Gaétan; Etter, Clément; Signarbieux, Constant; Wirth, Judith

2018-01-01

Weed control by crops through growth suppressive root exudates is a promising alternative to herbicides. Buckwheat ( Fagopyrum esculentum ) is known for its weed suppression and redroot pigweed ( Amaranthus retroflexus ) control is probably partly due to allelopathic root exudates. This work studies whether other weeds are also suppressed by buckwheat and if the presence of weeds is necessary to induce growth repression. Buckwheat and different weeds were co-cultivated in soil, separating roots by a mesh allowing to study effects due to diffusion. Buckwheat suppressed growth of pigweed, goosefoot and barnyard grass by 53, 42, and 77% respectively without physical root interactions, probably through allelopathic compounds. Root exudates were obtained from sand cultures of buckwheat (BK), pigweed (P), and a buckwheat/pigweed mixed culture (BK-P). BK-P root exudates inhibited pigweed root growth by 49%. Characterization of root exudates by UHPLC-HRMS and principal component analysis revealed that BK and BK-P had a different metabolic profile suggesting that buckwheat changes its root exudation in the presence of pigweed indicating heterospecific recognition. Among the 15 different markers, which were more abundant in BK-P, tryptophan was identified and four others were tentatively identified. Our findings might contribute to the selection of crops with weed suppressive effects.

An in-house assay for BK polyomavirus quantification using the Abbott m2000 RealTime system.

PubMed

Muldrew, Kenneth L; Lovett, Jennie L

2013-11-01

BK polyomavirus (BKPyV) quantification is useful for monitoring renal transplant patient response to therapy. The Abbott m2000 RealTime System employed by some clinical laboratories to perform US Food and Drug Administration-approved assays can also be used to develop in-house assays such as the one presented here. This study aimed to validate an in-house quantitative real-time PCR assay targeting the BKPyV major capsid VP1 gene for assessment of viral load using the Abbott m2000 RealTime System. BKPyV load was measured in 95 urine and plasma samples previously tested for BKPyV by one of three laboratories (46 BKPyV-positive samples consisting of 35 plasma and 11 urine samples; 49 samples negative for BKPyV consisting of 47 plasma and two urine samples). Two additional plasma specimens from the College of American Pathologists proficiency testing survey were also analysed. Precision studies were performed by diluting a high-viral-titre patient sample into BKPyV-negative pooled plasma to create high-positive (6.16 log10 copies ml(-1)) and low-positive (3.16 log10 copies ml(-1)) samples. For precision studies of inter-assay variability, a high-positive (7.0 log10 copies ml(-1)) and a low-positive (3.0 log10 copies ml(-1)) sample were measured in 20 separate runs. The assay's limit of quantification and limit of detection were 2.70 and 2.25 log10 copies ml(-1), respectively. The assay was linear from 2.70 to 9.26 log10 copies ml(-1). Of the 48 known positives, 43 were detected as positive, with three reported by the reference laboratory as values lower than the limit of detection. Two known positives at 3.27 and 3.80 log10 copies ml(-1) tested negative by the m2000 BKPyV assay. Of the 49 known negative samples, 48 were negative by the m2000 BKPyV load assay, with one sample confirmed positive by a reference laboratory. Qualitative analysis prior to discrepancy testing demonstrated a sensitivity of 89.58 % and a specificity of 97.96 %. Precision studies

Bruel and Kjaer 4944 Microphone Grid Frequency Response Function System Identification

NASA Technical Reports Server (NTRS)

Bennett, Reginald; Lee, Erik

2010-01-01

Br el & Kjaer (B&K) 4944B pressure field microphone was judiciously selected to measure acoustic environments, 400Hz 50kHz, in close proximity of the nozzle during multiple firings of solid propellant rocket motors. It is well known that protective grids can affect the frequency response of microphones. B&K recommends operation of the B&K 4944B without a protective grid when recording measurements above 10 to 15 kHz.

Chemotherapy of Rodent Malaria.

DTIC Science & Technology

1981-09-01

floxacrine analogue WR* (BK 02771) which remained fully effective against P.y.nigeriensis challenge seven days after treatment and was still partially...In particular we note that the Mannich base WR 194965 is highly active sc against the N strain and the moderately chloroquine resistant RC strain. The...this line. Floxacrine and the two floxacrine analogues WR* (BK02771) and WR* (BK 02780) have been compared and, whilst both analogues are markedj

Calcium Activated K+ Channels in The Electroreceptor of the Skate Confirmed by Cloning. Details of Subunits and Splicing

PubMed Central

King, Benjamin L.; Shi, Ling Fang; Kao, Peter; Clusin, William T.

2015-01-01

Elasmobranchs detect small potentials using excitable cells of the ampulla of Lorenzini which have calcium-activated K+ channels, first described in l974. A distinctive feature of the outward current in voltage clamped ampullae is its apparent insensitivity to voltage. The sequence of a BK channel α isoform expressed in the ampulla of the skate was characterized. A signal peptide is present at the beginning of the gene. When compared to human isoform 1 (the canonical sequence), the largest difference was absence of a 59 amino acid region from the S8-S9 intracellular linker that contains the strex regulatory domain. The ampulla isoform was also compared with the isoform predicted˜ in late skate embryos where strex was also absent. The BK voltage sensors were conserved in both skate isoforms. Differences between the skate and human BK channel included alternative splicing. Alternative splicing occurs at seven previously defined sites that are characteristic for BK channels in general and hair cells in particular. Skate BK sequences were highly similar to the Australian ghost shark and several other vertebrate species. Based on alignment of known BK sequences with the skate genome and transcriptome, there are at least two isoforms of Kcnma1α expressed in the skate. One of the β subunits (β4), which is known to decrease voltage sensitivity, was also identified in the skate genome and transcriptome and in the ampulla. These studies advance our knowledge of BK channels and suggest further studies in the ampulla and other excitable tissues. PMID:26687710

Calcium activated K⁺ channels in the electroreceptor of the skate confirmed by cloning. Details of subunits and splicing.

PubMed

King, Benjamin L; Shi, Ling Fang; Kao, Peter; Clusin, William T

2016-03-01

Elasmobranchs detect small potentials using excitable cells of the ampulla of Lorenzini which have calcium-activated K(+) channels, first described in 1974. A distinctive feature of the outward current in voltage clamped ampullae is its apparent insensitivity to voltage. The sequence of a BK channel α isoform expressed in the ampulla of the skate was characterized. A signal peptide is present at the beginning of the gene. When compared to human isoform 1 (the canonical sequence), the largest difference was absence of a 59 amino acid region from the S8-S9 intra-cellular linker that contains the strex regulatory domain. The ampulla isoform was also compared with the isoform predicted in late skate embryos where strex was also absent. The BK voltage sensors were conserved in both skate isoforms. Differences between the skate and human BK channel included alternative splicing. Alternative splicing occurs at seven previously defined sites that are characteristic for BK channels in general and hair cells in particular. Skate BK sequences were highly similar to the Australian ghost shark and several other vertebrate species. Based on alignment of known BK sequences with the skate genome and transcriptome, there are at least two isoforms of Kcnma1α expressed in the skate. One of the β subunits (β4), which is known to decrease voltage sensitivity, was also identified in the skate genome and transcriptome and in the ampulla. These studies advance our knowledge of BK channels and suggest further studies in the ampulla and other excitable tissues. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluating the impact of pre-transplant desensitization utilizing a plasmapheresis and low-dose intravenous immunoglobulin protocol on BK viremia in renal transplant recipients.

PubMed

Gabardi, S; Townsend, K; Martin, S T; Chandraker, A

2013-08-01

A correlation exists between polyomavirus BK (BKV) viremia in renal transplant recipients (RTR) and the degree of immunosuppression. However, the impact of pre-transplant desensitization on the incidence of BKV viremia is unknown. This retrospective study evaluated living-donor RTR between January 2004 and December 2008 receiving routine BKV viral load monitoring. Patients were divided into those who underwent pre-transplant desensitization (n = 20) and those who did not (n = 71). The primary endpoint was the incidence of BKV viremia at 1 year post transplant. All demographic data were similar, except for more female patients (65% vs. 36.6%; P = 0.0392) in the desensitized group. More desensitized patients had a previous transplant (75% vs. 12.7%; P < 0.0001) and were more likely to be induced with basiliximab (75% vs. 35.2%; P = 0.0021). Following transplantation, antibody-mediated rejection (AMR) rates were highest in the desensitized group (55% vs. 1.4%; P < 0.0001). The incidence of BKV viremia at 1 year post transplant was significantly higher in desensitized patients (45% vs. 19.7%; P = 0.0385). Desensitization was also associated with a higher prevalence of BKV viremia at any time post transplant (50% vs. 22.5%; P = 0.0245), polyomavirus-associated nephropathy (20% vs. 2.8%; P = 0.0198) and BKV-related allograft loss (10% vs. 0%; P = 0.0464). Also of note, in a subgroup analysis of only our desensitized patients, it did not appear that development of AMR significantly impacted the incidence of BKV viremia in these individuals. This analysis reveals that pre-transplant desensitization significantly increases the risk for BKV viremia and nephropathy. © 2013 John Wiley & Sons A/S.

Impact of HMG-CoA reductase inhibitors on the incidence of polyomavirus-associated nephropathy in renal transplant recipients with human BK polyomavirus viremia

PubMed Central

Gabardi, S.; Ramasamy, S.; Kim, M.; Klasek, R.; Carter, D.; Mackenzie, M.R.; Chandraker, A.; Tan, C.S.

2015-01-01

Introduction Up to 20% of renal transplant recipients (RTR) will develop human BK polyomavirus (BKPyV) viremia. BKPyV viremia is a pre-requisite of polyomavirus-associated nephropathy (PyVAN). Risk of BKPyV infections increases with immunosuppression. Currently, the only effective therapy against PyVAN is reductions in immunosuppression; but this may increase the risk of rejection. In vitro data have shown that pravastatin dramatically decreased caveolin-1 expression in human renal proximal tubular epithelial cells (HRPTEC) and suppressed BKPyV infection in these cells. Based on these data, we postulated that statin therapy may prevent the progression of BKPyV viremia to PyVAN. Patients and methods A multicenter, retrospective study was conducted in adult RTR transplanted between July 2005 and March 2012. All patients with documented BKPyV viremia (viral load >500 copies/mL on 2 consecutive tests) were included. Group I consisted of patients taking a statin before the BKPyV viremia diagnosis (n = 32), and Group II had no statin exposure before or after the BKPyV viremia diagnosis (n = 36). The primary endpoint was the incidence of PyVAN. Results Demographic data, transplant characteristics, and the degree of immunosuppression (i.e., induction/maintenance therapies, rejection treatment) were similar between the groups, with the exception of more diabetics in Group I. The incidence of PyVAN was comparable between the 2 groups (Group I = 28.1% vs. Group II = 41.7%; P = 0.312). Conclusions Despite the proven in vitro effectiveness of pravastatin preventing BKPyV infection in HRPTEC, statins at doses maximized for cholesterol lowering, in RTR with BKPyV viremia, did not prevent progression to PyVAN. PMID:25989423

Simultaneous estimation of aerosol optical constants and size distribution from angular light-scattering measurement signals

NASA Astrophysics Data System (ADS)

He, Zhen-Zong; Liang, Dong; Mao, Jun-Kui; Han, Xing-Si

2018-05-01

Not Available Project supported by the Jiangsu Provincial Natural Science Foundation, China (Grant Nos. BK20170800 and BK20160794) and the National Natural Science Foundation of China (Grant No. 51606095).

Kinin receptor classification.

PubMed

Regoli, D; Jukic, D; Tousignant, C; Rhaleb, N E

1992-01-01

Apparent affinities of kinin agonists and antagonists were determined in terms of pD2 and pA2 respectively, on three isolated smooth muscles: rabbit jugular vein (Rb.J.V.), rabbit aorta (Rb.A.) and guinea pig ileum (G.P.I.). Both kinin agonists and antagonists were evaluated for their ability to induce the release of histamine from rat mastocytes. Our results indicate that the kininase I metabolites (desArg9-BK and desArg10-KD) were inactive on Rb.J.V. and G.P.I. (B2 preparations) and were full agonists on Rb.A. (B1) while [Tyr(Me)8]-BK and [Hyp3,Tyr(Me)8]-BK were inactive on Rb.A. and maintain a high affinity on Rb.J.V. and G.P.I. In addition, [Hyp3]-BK was a potent agonist on Rb.J.V. (pD2 = 8.88) and was of a moderate affinity on G.P.I. (pD2 = 7.27). On the other hand, the affinity of [Aib7]-BK was identical to that of BK on G.P.I. (pD2 = 7.90) but drastically reduced in Rb.J.V. (pD2 = 6.28). Conctractile effects of kinins in the Rb.J.V. and G.P.I. were reduced or eliminated by B2 receptor antagonists but at different concentration levels (e.g. DArg[Hyp3,DPhe7,Leu8]-BK showed pA2 values of 8.86 on Rb.J.V., but only 6.77 on G.P.I. DArg[Hyp3,Gly6,Leu8]BK showed high affinity on Rb.J.V. (pA2 = 7.60) but was a full agonist on G.P.I. Conversely, DArg[Tyr3,DPhe7,Leu8,BK] showed high agonistic activity on Rb.J.V. (pD2 = 8.30, alpha E = 1.0) and showed a pA2 value of 6.80 on G.P.I. All compounds (agonists and antagonists) were quite potent on histamine release induced in rat mastocytes. [Arg1(Tos),Hyp3,Thi5,DTic7,Oic8]-BK and DArg[Hyp3,Thi5,DTic7,Oic8]-BK showed almost similar pA2 values on both Rb.J.V. and G.P.I., but were inactive on Rb.A. (B1). These results suggest that kinins act on at least four functional sites: B1 (Rb.A.), B2A (Rb.J.V.), B2B (G.P.I.) and BH. However, there is no clear evidence of a kinin receptor on rat mast cells and the release of histamine may simply be a non-receptor phenomenon. Our data also show that B2A and B2B receptor subtypes might

[Radiobiological effects on plants and animals within Semipalatinsk Test Site (Kazakhstan)].

PubMed

Mozolin, E M; Geras'kin, S A; Minkenova, K S

2008-01-01

The Semipalatinsk Test Site (STS) was the main place of nuclear devices tests in the former Soviet Union. From 1949 to 1989 about 460 nuclear explosions have been carried out at STS. Radioactive contamination of STS territory has the extremely non-uniform character. The main dose-forming radionuclides are 137Cs, 90Sr, 152Eu, as well as 154Eu, 60CO, 239,240Pu and 241Am. The greatest specific activity of 137Cs and 239,240Pu in ground are n x 10(3) kBk/kg, 152Eu - 96 kBk/kg, 154Eu - 10.4 kBk/kg, 60Co - 20.5 kBk/kg, 241Am - 15 kBk/kg. However, up to now, within STS sites exists where gamma-dose rate comes to 60 microGy/h, that is enough for induction reliable biological effects in animals and plants. Inhabiting territory of STS plants and animals are characterized by increased level of mutagenesis, changes of morpho-anatomic indices and parameters of peripheral blood, by the increase of asymmetry bilateral indices, change of composition and structure of communities.

Inhibition of Rat 5α-Reductase Activity and Testosterone-Induced Sebum Synthesis in Hamster Sebocytes by an Extract of Quercus acutissima Cortex

PubMed Central

Koseki, Junichi; Matsumoto, Takashi; Matsubara, Yosuke; Tsuchiya, Kazuaki; Mizuhara, Yasuharu; Sekiguchi, Kyoji; Nishimura, Hiroaki; Watanabe, Junko; Kaneko, Atsushi; Hattori, Tomohisa; Maemura, Kazuya; Kase, Yoshio

2015-01-01

Objective. Bokusoku (BK) is an extract from the Quercus cortex used in folk medicine for treatment of skin disorders and convergence, and is present in jumihaidokuto, a traditional Japanese medicine that is prescribed for purulent skin diseases like acne vulgaris. The excess of sebum production induced by androgen is involved in the development of acne. Our aim is to examine whether BK and its constituents inhibit testosterone metabolism and testosterone-induced sebum synthesis. Methods. Measurements of 5α-reductase activity and lipogenesis were performed using rat liver microsomes and hamster sebocytes, respectively. Results. BK dose-dependently reduced the conversion of testosterone to a more active androgen, dihydrotestosterone in a 5α-reductase enzymatic reaction. Twenty polyphenols in BK categorized as gallotannin, ellagitannin, and flavonoid were identified by LC-MS/MS. Nine polyphenols with gallate group, tetragalloyl glucose, pentagalloyl glucose, eugeniin, 1-desgalloyl eugeniin, casuarinin, castalagin, stenophyllanin C, (−)-epicatechin gallate, and (−)-epigallocatechin gallate, inhibited testosterone metabolism. In particular, pentagalloyl glucose showed the strongest activity. BK and pentagalloyl glucose suppressed testosterone-induced lipogenesis, whereas they weakly inhibited the lipogenic action of insulin. Conclusions. BK inhibited androgen-related pathogenesis of acne, testosterone conversion, and sebum synthesis, partially through 5α-reductase inhibition, and has potential to be a useful agent in the therapeutic strategy of acne. PMID:25709710

In vitro inactivation of Chlamydia trachomatis and of a panel of DNA (HSV-2, CMV, adenovirus, BK virus) and RNA (RSV, enterovirus) viruses by the spermicide benzalkonium chloride.

PubMed

Bélec, L; Tevi-Benissan, C; Bianchi, A; Cotigny, S; Beumont-Mauviel, M; Si-Mohamed, A; Malkin, J E

2000-11-01

Kinetics of inactivation by the detergent spermicide benzalkonium chloride (BZK) of Chlamydia trachomatis and of a panel of DNA viruses [herpes simplex virus hominis type 2 (HSV-2), cytomegalovirus (CMV), adenovirus (ADV) and BK virus (BKV)] and RNA [respiratory syncytial virus (RSV) and enterovirus (ENV)] were established in accordance with a standardized in vitro protocol. After a 5 min incubation, inactivation of >95% of HSV-2 and CMV was obtained at a concentration of 0.0025% (w/v) (25 Ig/L); concentrations as low as 0.0005%, 0.0050% and 0.0125%, induced a 3.0 log10 reduction in infectivity of HSV-2 and CMV, RSV and ADV, respectively. After a 60 min incubation, concentrations of 0.0125% and 0.050% provided a 3.0 log10 reduction in infectivity of ENV and BKV, respectively. These features indicate that sensitivity to BZK was very high (HSV-2 and CMV) or high (RSV) for enveloped viruses, intermediate (ADV) or low (ENV and BKV) for non-enveloped viruses. Furthermore, BZK had marked antichlamydial activity, showing >99% killing after only a 1 min incubation at a concentration of 0.00125%. BZK demonstrates potent in vitro activity against the majority of microorganisms causing sexually transmitted infectious diseases, including those acting as major genital cofactors of human immunodeficiency virus transmission. These attributes qualify BZK as a particularly attractive candidate for microbicide development.

Curbing Charging Currents in Pulsed Field Emission by Prolonging Pulse Edges

NASA Astrophysics Data System (ADS)

Wei, Jin-Di; Li, Yun-Hui; Zhang, Geng-Min; Yang, Jin; Xing, Ying-Jie; Zhou, Wen-Sheng

2018-05-01

Not Available Supported by the Natural Science Foundation of Jiangsu Province of China under Grant Nos BK20161243 and BK20161242, and the National Natural Science Foundation of China under Grant No 61774007.

Vasoinhibins regulate the inner and outer blood-retinal barrier and limit retinal oxidative stress.

PubMed

Arredondo Zamarripa, David; Díaz-Lezama, Nundehui; Meléndez García, Rodrigo; Chávez Balderas, Jesús; Adán, Norma; Ledesma-Colunga, Maria G; Arnold, Edith; Clapp, Carmen; Thebault, Stéphanie

2014-01-01

Vasoinhibins are prolactin fragments present in the retina, where they have been shown to prevent the hypervasopermeability associated with diabetes. Enhanced bradykinin (BK) production contributes to the increased transport through the blood-retina barrier (BRB) in diabetes. Here, we studied if vasoinhibins regulate BRB permeability by targeting the vascular endothelium and retinal pigment epithelium (RPE) components of this barrier. Intravitreal injection of BK in male rats increased BRB permeability. Vasoinhibins prevented this effect, as did the B2 receptor antagonist Hoe-140. BK induced a transient decrease in mouse retinal and brain capillary endothelial monolayer resistance that was blocked by vasoinhibins. Both vasoinhibins and the nitric oxide (NO) synthase inhibitor L-NAME, but not the antioxidant N-acetyl cysteine (NAC), blocked the transient decrease in bovine umbilical vein endothelial cell (BUVEC) monolayer resistance induced by BK; this block was reversed by the NO donor DETANONOate. Vasoinhibins also prevented the BK-induced actin cytoskeleton redistribution, as did L-NAME. BK transiently decreased human RPE (ARPE-19) cell monolayer resistance, and this effect was blocked by vasoinhibins, L-NAME, and NAC. DETANONOate reverted the blocking effect of vasoinhibins. Similar to BK, the radical initiator Luperox induced a reduction in ARPE-19 cell monolayer resistance, which was prevented by vasoinhibins. These effects on RPE resistance coincided with actin cytoskeleton redistribution. Intravitreal injection of vasoinhibins reduced the levels of reactive oxygen species (ROS) in retinas of streptozotocin-induced diabetic rats, particularly in the RPE and capillary-containing layers. Thus, vasoinhibins reduce BRB permeability by targeting both its main inner and outer components through NO- and ROS-dependent pathways, offering potential treatment strategies against diabetic retinopathies.

Bradykinin increases blood-tumor barrier permeability by down-regulating the expression levels of ZO-1, occludin, and claudin-5 and rearranging actin cytoskeleton.

PubMed

Liu, Li-Bo; Xue, Yi-Xue; Liu, Yun-Hui; Wang, Yi-Bao

2008-04-01

Bradykinin (BK) has been shown to open blood-tumor barrier (BTB) selectively and to increase permeability of the BTB transiently, but the mechanism is unclear. This study was performed to determine whether BK opens the BTB by affecting the tight junction (TJ)-associated proteins zonula occluden-1 (ZO-1), occludin, and caludin-5 and cytoskeleton protein filamentous actin (F-actin). In rat brain glioma model and BTB model in vitro, we find that the protein expression levels of ZO-1, occludin, and claudin-5 are attenuated by BK induction. Immunohistochemistry and immunofluorescence assays show that the attenuated expression of ZO-1, occludin, and claudin-5 and F-actin is most obvious in the smaller tumor capillaries (<20 microm) after BK infusion, and there is no change in the larger tumor capillaries (>20 microm). The redistribution of ZO-1, occludin, and claudin-5 and rearrangement of F-actin in brain microvascular endothelial cells are observed at the same time. Meanwhile, Evans blue assay shows that the permeability of BTB increases after BK infusion. Transmission electron microscopy indicates that TJ is opened and that pinocytotic vesicular density is increased. Transendothelial electrical resistance (TEER) and horseradish peroxidase flux assays also reveal that TJ is opened by BK induction. In addition, radioimmunity and Western blot assay reveal a significant decrease in expression levels of cAMP and catalytic subunit of protien kinase A (PKAcs) of tumor tissue. This study demonstrates that the increase of BK-mediated BTB permeability is associated with the down-regulation of ZO-1, occludin, and claudin-5 and the rearrangement of F-actin and that cAMP/PKA signal transduction system might be involved in the modulating process.

Effects of single or combined dietary supplementation of β-glucan and kefir on growth performance, blood characteristics and meat quality in broilers.

PubMed

Cho, J H; Zhang, Z F; Kim, I H

2013-01-01

1. This study was conducted to evaluate the effects of dietary β-glucan and kefir (a fermented milk product) on growth performance, blood profiles, relative organ weight and meat quality in broilers. 2. A total of 375 day-of-hatch mixed sex ROSS 308 broilers (BW of 46 ± 0.1 g) were used in a 5-week experiment and randomly allotted to one of the following dietary treatments: (1) NC, basal diet; (2) PC, basal diet + 40 mg/kg of avilamycin; (3) B, NC + 0.1% β-glucan; (4) K, NC + 0.1% kefir; (5) BK, NC + 0.1% β-glucan + 0.1% kefir. 3. During weeks 0-3, broilers in B, K and BK treatments had higher body weight gain (BWG) than those in NC treatment. During weeks 4-5, BK treatment had a higher BWG than NC treatment. Overall, broilers given PC, K and BK diets had higher BWG than those given NC diet. The feed efficiency ratio (FCR) was improved by PC treatment. 4. Relative liver weight was increased by B treatment, whereas the relative weight of breast meat and gizzard was higher in BK group than that in NC group. Broilers given PC, B and BK diets had greater breast meat redness value and reduced drip loss at d 5 and d 7. The cooking loss was also reduced by B and BK treatments compared with NC treatment. 5. In conclusion, the results suggested that inclusion of 0.1% β-glucan and 0.1% kefir, either individually or combined, would improve growth performance and benefit meat quality in broiler chickens.

Vasoinhibins regulate the inner and outer blood-retinal barrier and limit retinal oxidative stress

PubMed Central

Arredondo Zamarripa, David; Díaz-Lezama, Nundehui; Meléndez García, Rodrigo; Chávez Balderas, Jesús; Adán, Norma; Ledesma-Colunga, Maria G.; Arnold, Edith; Clapp, Carmen; Thebault, Stéphanie

2014-01-01

Vasoinhibins are prolactin fragments present in the retina, where they have been shown to prevent the hypervasopermeability associated with diabetes. Enhanced bradykinin (BK) production contributes to the increased transport through the blood-retina barrier (BRB) in diabetes. Here, we studied if vasoinhibins regulate BRB permeability by targeting the vascular endothelium and retinal pigment epithelium (RPE) components of this barrier. Intravitreal injection of BK in male rats increased BRB permeability. Vasoinhibins prevented this effect, as did the B2 receptor antagonist Hoe-140. BK induced a transient decrease in mouse retinal and brain capillary endothelial monolayer resistance that was blocked by vasoinhibins. Both vasoinhibins and the nitric oxide (NO) synthase inhibitor L-NAME, but not the antioxidant N-acetyl cysteine (NAC), blocked the transient decrease in bovine umbilical vein endothelial cell (BUVEC) monolayer resistance induced by BK; this block was reversed by the NO donor DETANONOate. Vasoinhibins also prevented the BK-induced actin cytoskeleton redistribution, as did L-NAME. BK transiently decreased human RPE (ARPE-19) cell monolayer resistance, and this effect was blocked by vasoinhibins, L-NAME, and NAC. DETANONOate reverted the blocking effect of vasoinhibins. Similar to BK, the radical initiator Luperox induced a reduction in ARPE-19 cell monolayer resistance, which was prevented by vasoinhibins. These effects on RPE resistance coincided with actin cytoskeleton redistribution. Intravitreal injection of vasoinhibins reduced the levels of reactive oxygen species (ROS) in retinas of streptozotocin-induced diabetic rats, particularly in the RPE and capillary-containing layers. Thus, vasoinhibins reduce BRB permeability by targeting both its main inner and outer components through NO- and ROS-dependent pathways, offering potential treatment strategies against diabetic retinopathies. PMID:25368550

The effect of peptidase inhibitors on bradykinin-induced bronchoconstriction in guinea-pigs in vivo.

PubMed Central

Ichinose, M.; Barnes, P. J.

1990-01-01

1. Bradykinin (BK) instilled directly into the airway lumen caused bronchoconstriction in anaesthetized, mechanically ventilated guinea-pigs in the presence of propranolol (1 mg kg-1 i.v.). The geometric mean dose of BK required to produce 100% increase in airway opening pressure (PD100) was 22.9 nmol (95% c.i. 11.7-44.6 nmol). 2. The dose-response curve for the effect of instilled BK was significantly shifted to the left by the angiotensin converting enzyme (ACE) inhibitor, captopril (5 and 50 nmol instillation, PD100 = 3.0, 95% c.i. 0.98-8.9, and 2.0 nmol, 95% c.i. 0.65-6.2 nmol, respectively). 3. The neutral endopeptidase (NEP) inhibitor, phosphoramidon (5 and 50 nmol instillation) also shifted the dose-response curve for the effect of instilled BK; the PD100 values = 2.2 (95% c.i. 0.40-11.7) and 1.8 nmol (95% c.i. 0.87-3.5 nmol), respectively. 4. After pretreatment with captopril (50 nmol) and phosphoramidon (50 nmol) in combination, the dose-response curve for the effect of instilled BK (PD100 = 1.1 nmol, 95% c.i. 0.37-3.2 nmol) was similar to that obtained in the presence of each inhibitor used alone. 5. The kinase I inhibitor, DL-2-mercaptomethyl-3-guanidinoethylthiopropionic acid (50 nmol instillation) failed to alter the dose-response curve to instilled BK (PD100 = 14.6 nmol, 95% c.i. 6.7-32.0 nmol). 6. These data suggest that both ACE and NEP degrade BK in the airway lumen, but that kininase I is not involved. PMID:2282470

#TheDress: Categorical perception of an ambiguous color image.

PubMed

Lafer-Sousa, Rosa; Conway, Bevil R

2017-10-01

We present a full analysis of data from our preliminary report (Lafer-Sousa, Hermann, & Conway, 2015) and test whether #TheDress image is multistable. A multistable image must give rise to more than one mutually exclusive percept, typically within single individuals. Clustering algorithms of color-matching data showed that the dress was seen categorically, as white/gold (W/G) or blue/black (B/K), with a blue/brown transition state. Multinomial regression predicted categorical labels. Consistent with our prior hypothesis, W/G observers inferred a cool illuminant, whereas B/K observers inferred a warm illuminant; moreover, subjects could use skin color alone to infer the illuminant. The data provide some, albeit weak, support for our hypothesis that day larks see the dress as W/G and night owls see it as B/K. About half of observers who were previously familiar with the image reported switching categories at least once. Switching probability increased with professional art experience. Priming with an image that disambiguated the dress as B/K biased reports toward B/K (priming with W/G had negligible impact); furthermore, knowledge of the dress's true colors and any prior exposure to the image shifted the population toward B/K. These results show that some people have switched their perception of the dress. Finally, consistent with a role of attention and local image statistics in determining how multistable images are seen, we found that observers tended to discount as achromatic the dress component that they did not attend to: B/K reporters focused on a blue region, whereas W/G reporters focused on a golden region.

#TheDress: Categorical perception of an ambiguous color image

PubMed Central

Lafer-Sousa, Rosa; Conway, Bevil R.

2017-01-01

We present a full analysis of data from our preliminary report (Lafer-Sousa, Hermann, & Conway, 2015) and test whether #TheDress image is multistable. A multistable image must give rise to more than one mutually exclusive percept, typically within single individuals. Clustering algorithms of color-matching data showed that the dress was seen categorically, as white/gold (W/G) or blue/black (B/K), with a blue/brown transition state. Multinomial regression predicted categorical labels. Consistent with our prior hypothesis, W/G observers inferred a cool illuminant, whereas B/K observers inferred a warm illuminant; moreover, subjects could use skin color alone to infer the illuminant. The data provide some, albeit weak, support for our hypothesis that day larks see the dress as W/G and night owls see it as B/K. About half of observers who were previously familiar with the image reported switching categories at least once. Switching probability increased with professional art experience. Priming with an image that disambiguated the dress as B/K biased reports toward B/K (priming with W/G had negligible impact); furthermore, knowledge of the dress's true colors and any prior exposure to the image shifted the population toward B/K. These results show that some people have switched their perception of the dress. Finally, consistent with a role of attention and local image statistics in determining how multistable images are seen, we found that observers tended to discount as achromatic the dress component that they did not attend to: B/K reporters focused on a blue region, whereas W/G reporters focused on a golden region. PMID:29090319

Inertially Stabilized Platforms for SATCOM On-The-Move Applications: A Hybrid Open/Closed-Loop Antenna Pointing Strategy

DTIC Science & Technology

2008-06-01

Photo courtesy of www.mathworks.com. Next, Equation (3.16) translates the aircraft disturbance rates through the de - sired local azimuth and elevation...Hessian matrix of the assumed quadratic cost function [34–36]. Equation (4.11) exactly de - termines the minimum of a quadratic function in a single...according to: Bkpk = −gk (4.21) Bk+1 = Bk +Qk (4.22) where Bk in some way approximates Gk from (4.12), and Qk is an update matrix de - pendent upon xk

Impact of HMG-CoA reductase inhibitors on the incidence of polyomavirus-associated nephropathy in renal transplant recipients with human BK polyomavirus viremia.

PubMed

Gabardi, S; Ramasamy, S; Kim, M; Klasek, R; Carter, D; Mackenzie, M R; Chandraker, A; Tan, C S

2015-08-01

Up to 20% of renal transplant recipients (RTR) will develop human BK polyomavirus (BKPyV) viremia. BKPyV viremia is a pre-requisite of polyomavirus-associated nephropathy (PyVAN). Risk of BKPyV infections increases with immunosuppression. Currently, the only effective therapy against PyVAN is reductions in immunosuppression, but this may increase the risk of rejection. In vitro data have shown that pravastatin dramatically decreased caveolin-1 expression in human renal proximal tubular epithelial cells (HRPTEC) and suppressed BKPyV infection in these cells. Based on these data, we postulated that statin therapy may prevent the progression of BKPyV viremia to PyVAN. A multicenter, retrospective study was conducted in adult RTR transplanted between July 2005 and March 2012. All patients with documented BKPyV viremia (viral load >500 copies/mL on 2 consecutive tests) were included. Group I consisted of patients taking a statin before the BKPyV viremia diagnosis (n = 32), and Group II had no statin exposure before or after the BKPyV viremia diagnosis (n = 36). The primary endpoint was the incidence of PyVAN. Demographic data, transplant characteristics, and the degree of immunosuppression (i.e., induction/maintenance therapies, rejection treatment) were similar between the groups, with the exception of more diabetics in Group I. The incidence of PyVAN was comparable between the 2 groups (Group I = 28.1% vs. Group II = 41.7%; P = 0.312). Despite the proven in vitro effectiveness of pravastatin preventing BKPyV infection in HRPTEC, statins at doses maximized for cholesterol lowering, in RTR with BKPyV viremia, did not prevent progression to PyVAN. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Coinfection with Epstein–Barr Virus (EBV), Human Papilloma Virus (HPV) and Polyoma BK Virus (BKPyV) in Laryngeal, Oropharyngeal and Oral Cavity Cancer

PubMed Central

Drop, Bartłomiej; Strycharz-Dudziak, Małgorzata; Kliszczewska, Ewa; Polz-Dacewicz, Małgorzata

2017-01-01

Most research providing evidence for the role of oncogenic viruses in head and neck squamous cell carcinoma (SCC) development is focused on one type of virus without analyzing possible interactions between two or more types of viruses. The aim of this study was to analyse the prevalence of co-infection with human papillomavirus (HPV), Epstein–Barr virus (EBV) and polyoma BK virus (BKPyV) in oral, oropharyngeal and laryngeal squamous cell carcinomas in Polish patients. The correlations between viral infection, SCC, demographic parameters, evidence of metastases and grading were also investigated. Fresh-frozen tumour tissue samples were collected from 146 patients with laryngeal, oropharyngeal and oral cancer. After DNA extraction, the DNA of the studied viruses was detected using polymerase chain rection (PCR) assay. Males (87.7%) with a history of smoking (70.6%) and alcohol abuse (59.6%) prevailed in the studied group. Histological type G2 was recognized in 64.4% cases. The patients were most frequently diagnosed with T2 stage (36.3%) and with N1 stage (45.8%). Infection with at least two viruses was detected in 56.2% of patients. In this group, co-infection with HPV/EBV was identified in 34.1% of cases, EBV/BKV in 23.2%, HPV/BKV in 22.0%, and HPV/EBV/BKV in 20.7%. No difference of multiple infection in different locations of cancer was observed. The prevalence of poorly differentiated tumours (G3) was more frequent in co-infection with all three viruses than EBV or BKV alone. A significant correlation was observed between tumour dimensions (T) and lymph-node involvement (N) in co-infected patients compared to single infection. Further studies are necessary to clarify whether co-infection plays an important role in the initiation and/or progression of oncogenic transformation of oral, oropharyngeal and laryngeal epithelial cells. PMID:29257122

Coinfection with Epstein-Barr Virus (EBV), Human Papilloma Virus (HPV) and Polyoma BK Virus (BKPyV) in Laryngeal, Oropharyngeal and Oral Cavity Cancer.

PubMed

Drop, Bartłomiej; Strycharz-Dudziak, Małgorzata; Kliszczewska, Ewa; Polz-Dacewicz, Małgorzata

2017-12-19

Most research providing evidence for the role of oncogenic viruses in head and neck squamous cell carcinoma (SCC) development is focused on one type of virus without analyzing possible interactions between two or more types of viruses. The aim of this study was to analyse the prevalence of co-infection with human papillomavirus (HPV), Epstein-Barr virus (EBV) and polyoma BK virus (BKPyV) in oral, oropharyngeal and laryngeal squamous cell carcinomas in Polish patients. The correlations between viral infection, SCC, demographic parameters, evidence of metastases and grading were also investigated. Fresh-frozen tumour tissue samples were collected from 146 patients with laryngeal, oropharyngeal and oral cancer. After DNA extraction, the DNA of the studied viruses was detected using polymerase chain rection (PCR) assay. Males (87.7%) with a history of smoking (70.6%) and alcohol abuse (59.6%) prevailed in the studied group. Histological type G2 was recognized in 64.4% cases. The patients were most frequently diagnosed with T2 stage (36.3%) and with N1 stage (45.8%). Infection with at least two viruses was detected in 56.2% of patients. In this group, co-infection with HPV/EBV was identified in 34.1% of cases, EBV/BKV in 23.2%, HPV/BKV in 22.0%, and HPV/EBV/BKV in 20.7%. No difference of multiple infection in different locations of cancer was observed. The prevalence of poorly differentiated tumours (G3) was more frequent in co-infection with all three viruses than EBV or BKV alone. A significant correlation was observed between tumour dimensions (T) and lymph-node involvement (N) in co-infected patients compared to single infection. Further studies are necessary to clarify whether co-infection plays an important role in the initiation and/or progression of oncogenic transformation of oral, oropharyngeal and laryngeal epithelial cells.

Resistance and aerobic exercise have similar effects on 24-h nutrient oxidation.

PubMed

Melanson, Edward L; Sharp, Teresa A; Seagle, Helen M; Donahoo, William T; Grunwald, Gary K; Peters, John C; Hamilton, Jere T; Hill, James O

2002-11-01

Whether resistance exercise is as effective as aerobic exercise for body-weight management is debated. To compare 24-h energy expenditure (EE) and macronutrient oxidation elicited by comparable bouts of stationary cycling (BK) and weightlifting (WTS). 24-h EE and macronutrient oxidation were measured in 10 nonobese male subjects on three occasions using whole-room indirect calorimetry. BK and WTS days were compared with a nonexercise control day (Con). During BK, subjects exercised for 49 +/- 7 min (mean +/- SEM) at 70% of OV(2max) and expended 546 +/- 16 kcal. During WTS, subjects performed a 70-min circuit consisting of four sets of 10 different exercises at 70% of exercise-specific 1-repetition maximum and expended 448 +/- 21 kcal (P < 0.001 vs BK). 24-h EE on BK and WTS days (2,787 +/- 76 kcal x d(-1), 2,730 +/- 106 kcal x d(-1), respectively, P > 0.05) was elevated compared with Con (2,260 +/- 96 kcal x d(-1), P < 0.001), but 24-h respiratory exchange ratio (RER) was not different. 24-h carbohydrate oxidation was significantly elevated on the exercise days (BK = 370 +/- 18 g x d(-1), WTS = 349 +/- 23 g x d(-1), P > 0.05) compared with Con (249 +/- 29 g x d(-1), P = 0.04). 24-h fat and protein oxidation were the same on BK, WTS, and Con days. EE and macronutrient oxidation in the periods after exercise also did not differ across conditions. In men, resistance exercise has a similar effect on 24-h EE and macronutrient oxidation as a comparable bout of aerobic exercise. Neither exercise produced an increase in 24-h fat oxidation above that observed on a nonexercise control day.

Children's reaction to depictions of healthy foods in fast-food television advertisements.

PubMed

Bernhardt, Amy M; Wilking, Cara; Gottlieb, Mark; Emond, Jennifer; Sargent, James D

2014-05-01

Since 2009, quick-service restaurant chains, or fast-food companies, have agreed to depict healthy foods in their advertising targeted at children. To determine how children interpreted depictions of milk and apples in television advertisements for children's meals by McDonald's and Burger King (BK) restaurants. Descriptive qualitative study in a rural pediatric practice setting in Northern New England. A convenience sample of 99 children (age range, 3-7 years) was shown depictions of healthy foods in fast-food advertisements that aired from July 1, 2010, through June 30, 2011. The images from McDonald's and BK showed milk and apples. Children were asked what they saw and not prompted to respond specifically to any aspect of the images. Two still images drawn from advertisements for healthy meals at McDonald's and BK. Children's responses were independently content coded to food category by 2 researchers. Among the 99 children participating, only 51 (52%) and 69 (70%) correctly identified milk from the McDonald's and BK images, respectively, with a significantly greater percentage correct (P = .02 for both) among older children. The children's recall of apples was significantly different by restaurant, with 79 (80%) mentioning apples when describing the McDonald's image and only 10 (10%) for the BK image (P < .001). The percentage correct was not associated with age in either case. Conversely, although french fries were not featured in either image, 80 children (81%) recalled french fries after viewing the BK advertisement. Of the 4 healthy food images, only depiction of apples by McDonald's was communicated adequately to the target audience. Representations of milk were inadequately communicated to preliterate children. Televised depictions of apple slices by BK misled the children in this study, although no action was taken by government or self-regulatory bodies.

Effect of neutral endopeptidase inhibitor on bradykinin-induced bronchoconstriction.

PubMed

Kamijo, Y; Hayashi, I; Soma, K; Ohwada, T; Majima, M

2001-11-21

To evaluate whether neutral endopeptidase (NEP) inhibitors have adverse respiratory effects, the influence of a NEP inhibitor on bradykinin (BK)-induced bronchoconstriction was investigated. In anesthetized and artificially ventilated guinea pigs, changes in airway opening pressure (Pao) were measured as an index of bronchoconstriction. An infusion of phosphoramidon (3 mg kg(-1) h(-1)), a NEP inhibitor, significantly enhanced the bronchoconstriction induced by high-dose BK (30 nmol kg(-1), i.v.). Capsaicin (0.1 mg kg(-1), i.v.) and SR48968 (0.3 mg kg(-1), i.v.), an NK2 receptor antagonist, significantly inhibited the phosphoramidon-induced enhancement of BK-induced bronchoconstriction, although FK888 (3 mg kg(-1), i.v.), an NK1 receptor antagonist, did not. Both neurokinin A (NKA) (0.1-3 nmol kg(-1), i.v.) and substance P (SP) (0.1-3 nmol kg(-1), i.v.) induced dose-dependent bronchoconstriction which was enhanced by phosphoramidon infusion, although these enhancements were more prominent in the NKA series. Phosphoramidon partially inhibited BK degradation in lung homogenate, and both NKA and SP degradation in the lung homogenate were significantly suppressed by phosphoramidon. In bronchoalveolar lavage fluid (BALF), levels of NKA and SP were significantly elevated after a bolus of BK with a phosphoramidon infusion. These results suggest that NEP inhibitors may have adverse respiratory effects resulting from inhibition of the degradation of neurokinins, but mainly of NKA, when a large amount of BK is generated.

Functional crosstalk between histone H2B ubiquitylation and H2A modifications and variants.

PubMed

Wojcik, Felix; Dann, Geoffrey P; Beh, Leslie Y; Debelouchina, Galia T; Hofmann, Raphael; Muir, Tom W

2018-04-11

Ubiquitylation of histone H2B at lysine residue 120 (H2BK120ub) is a prominent histone posttranslational modification (PTM) associated with the actively transcribed genome. Although H2BK120ub triggers several critical downstream histone modification pathways and changes in chromatin structure, less is known about the regulation of the ubiquitylation reaction itself, in particular with respect to the modification status of the chromatin substrate. Here we employ an unbiased library screening approach to profile the impact of pre-existing chromatin modifications on de novo ubiquitylation of H2BK120 by the cognate human E2:E3 ligase pair, UBE2A:RNF20/40. Deposition of H2BK120ub is found to be highly sensitive to PTMs on the N-terminal tail of histone H2A, a crosstalk that extends to the common histone variant H2A.Z. Based on a series of biochemical and cell-based studies, we propose that this crosstalk contributes to the spatial organization of H2BK120ub on gene bodies, and is thus important for transcriptional regulation.

Titanium Dioxide (TiO2) film as a new saturable absorber for generating mode-locked Thulium-Holmium doped all-fiber laser

NASA Astrophysics Data System (ADS)

Mohd Rusdi, Muhammad Farid; Latiff, Anas Abdul; Paul, Mukul Chandra; Das, Shyamal; Dhar, Anirban; Ahmad, Harith; Harun, Sulaiman Wadi

2017-03-01

We report the generation of mode-locked thulium-holmium doped fiber laser (THDFL) at 1979 nm. This is a first demonstration of mode-locked by using Titanium Dioxide bk [?up][?tjl=1000][?down]?clretain->(TiO2) film as a saturable absorber (SA). A piece of 1 mm×1 mm bk [?up][?tjl=1000][?down]?clretain->TiO2 film was sandwiched in between two fiber ferrule in the cavity. Fabrication process of bk [?up][?tjl=1000][?down]?clretain->TiO2 film incorporated a bk [?up][?tjl=1000][?down]?clretain->TiO2 and a polyvinyl alcohol (PVA). The stable 9 MHz repetition rate of mode-locked mode operation with 58 dB SNR was generated under pump power of 902-1062 mW. At maximum pump power, the mode-locked THDFL has output power and pulse energy of 15 mW and 1.66 nJ, respectively. Our results demonstrate the bk [?up][?tjl=1000][?down]?clretain->TiO2 can be used promisingly in ultrafast photonics applications.

Lie symmetry analysis and reduction for exact solution of (2+1)-dimensional Bogoyavlensky-Konopelchenko equation by geometric approach

NASA Astrophysics Data System (ADS)

Ray, S. Saha

2018-04-01

In this paper, the symmetry analysis and similarity reduction of the (2+1)-dimensional Bogoyavlensky-Konopelchenko (B-K) equation are investigated by means of the geometric approach of an invariance group, which is equivalent to the classical Lie symmetry method. Using the extended Harrison and Estabrook’s differential forms approach, the infinitesimal generators for (2+1)-dimensional B-K equation are obtained. Firstly, the vector field associated with the Lie group of transformation is derived. Then the symmetry reduction and the corresponding explicit exact solution of (2+1)-dimensional B-K equation is obtained.

Effect of Sb-doping on martensitic transformation and magnetocaloric effect in Mn-rich {{Mn}}_{50}{{Ni}}_{40}{{Sn}}_{10-x}{{Sb}}_{x}(x=1,2,3,{and}4) alloys

NASA Astrophysics Data System (ADS)

Shah, Ishfaq Ahmad; Hassan, Najam ul; Liu, Jun; Gong, Yuanyuan; Xu, Guizhou; Xu, Feng

2017-01-01

Not Available Project supported by the National Natural Science Foundation of China (Grant Nos. 51271093, 51571121, 11604148, and 51601092), the Fundamental Research Funds for the Central Universities, China (Grant Nos. 30920140111010, 30916011344, and 30916011345), Jiangsu Natural Science Foundation for Distinguished Young Scholars, China (Grant No. BK20140035), China Postdoctoral Science Foundation (Grant No. 2016M591851), the Natural Science Foundation of Jiangsu Province, China (Grant Nos. BK20160833 and BK20160829), Qing Lan Project, Six Talent Peaks Project in Jiangsu Province, China, and the Priority Academic Program Development of Jiangsu Higher Education Institutions, China.

Effect of subcutaneous Meloxicam on indicators of acute pain and distress after castration and branding in 2 mo old beef calves.

PubMed

Meléndez, D M; Marti, S; Pajor, E A; Moya, D; Gellatly, D; Janzen, E D; Schwartzkopf-Genswein, K S

2018-06-15

The aim of this study was to assess knife castration and knife castration + branding in 2-mo old calves, and the effect of a single dose of s.c. meloxicam at mitigating pain indicators. Seventy-one Angus crossbred bull calves (128 ± 18.5 kg of BW) were used in a 3 × 2 factorial design where main factors included procedure: sham (control calves, CT; n = 23), knife (KN; n = 24) or knife + branding (BK; n = 24) and medication: single s.c. administration of lactated ringer solution (NM; n = 35) or a single dose of 0.5 mg/kg of s.c. meloxicam (M; n = 36). Physiological samples were collected at T0, 60, 90, 120 and 180 min and on d 1, 2, 3 and 7 after procedure, while behavioral observations were evaluated at 2 to 4 h and 1, 2, 3 and 7 days after procedure. A procedure × time effect (P < 0.01) was observed for cortisol, where KN and BK calves had greater (P ≤ 0.01 ) cortisol concentrations than CT calves 60 min after the procedure, while BK calves had the greatest (P < 0.05) cortisol concentrations, followed by KN calves and by CT calves 90, 120 and 180 min after the procedure. A procedure × time effect (P = 0.01) was observed for tail flicks, where KN and BK calves had a greater (P < 0.05) number of tail flicks than CT calves on d 1 and 3, while BK calves had the greatest number of tail flicks, followed by KN calves, and then by CT calves on d 2. Haptoglobin had a procedure × medication × time interaction (P = 0.05), where BK-NM calves had greater haptoglobin concentrations than BK-M, KN-M and CT calves on d 1 and 3, while BK-NM and KN-NM calves had greater haptoglobin concentrations than BK-M, KN-M and CT calves on d 2 after the procedure. Lying duration and tail flicks had a medication effect (P = 0.04; P < 0.01) where M calves had greater (P < 0.05) lying duration and lower (P < 0.05) number of tail flicks than NM calves 2 to 4 h after procedure. No medication effects (P > 0.10) were observed for salivary cortisol, substance P and scrotal temperature min

Predictive value of serum bradykinin and desArg9-bradykinin levels for chemotherapeutic responses in active tuberculosis patients: A retrospective case series.

PubMed

Qian, Xu; Nguyen, Duc T M; Li, Yaojun; Lyu, Jianxin; Graviss, Edward A; Hu, Tony Y

2016-12-01

There is an urgent need for methods that can rapidly and accurately assess therapeutic responses in patients with active tuberculosis (TB) in order to predict treatment outcomes. Exposure to bacterial pathogens can rapidly activate the plasma contact system, triggering the release of bradykinin (BK) and its metabolite desArg 9 -bradykinin (DABK) to induce inflammation and innate immune responses. We hypothesized that serum BK and DABK levels might act as sensitive immune response signatures for changes in Mycobacterium tuberculosis (Mtb) burden, and therefore examined how serum levels of these markers corresponded with anti-TB therapy in a small cohort of active TB cases. Nanotrap Mass-Spectrometry (MS) was used to analyze serial blood specimens from 13 HIV-negative adults with microbiologically confirmed active TB who were treated with first-line anti-TB chemotherapy. MS signal for BK (m/z 1060.5) and DABK (m/z 904.5) serum peptides were evaluated at multiple time-points (before, during, and after treatment) to evaluate how BK and DABK levels corresponded with disease status. Serum BK levels declined from pretreatment baseline levels during the early stage anti-TB therapy (induction phase) and tended to remain below baseline levels during extended treatment (consolidation phase) and after therapy completion. BK levels were consistent with induction phase sputum culture conversions indicative of decreased Mtb burden reflecting good treatment responses. Serum DABK levels tended to increase during the induction phase and decrease at consolidation and post-therapy time points, which may indicate a shift from active disease to chronic inflammation to a disease free state. Elevated BK and DABK levels after treatment completion in one patient may be related to the subsequent recurrent TB disease. Our pilot data suggests that changes in the circulating BK and DABK levels in adult TB patients can be used as potential surrogate markers of the host response both early and

Alchemy: A Web 2.0 Real-time Quality Assurance Platform for Human Immunodeficiency Virus, Hepatitis C Virus, and BK Virus Quantitation Assays.

PubMed

Agosto-Arroyo, Emmanuel; Coshatt, Gina M; Winokur, Thomas S; Harada, Shuko; Park, Seung L

2017-01-01

The molecular diagnostics laboratory faces the challenge of improving test turnaround time (TAT). Low and consistent TATs are of great clinical and regulatory importance, especially for molecular virology tests. Laboratory information systems (LISs) contain all the data elements necessary to do accurate quality assurance (QA) reporting of TAT and other measures, but these reports are in most cases still performed manually: a time-consuming and error-prone task. The aim of this study was to develop a web-based real-time QA platform that would automate QA reporting in the molecular diagnostics laboratory at our institution, and minimize the time expended in preparing these reports. Using a standard Linux, Nginx, MariaDB, PHP stack virtual machine running atop a Dell Precision 5810, we designed and built a web-based QA platform, code-named Alchemy. Data files pulled periodically from the LIS in comma-separated value format were used to autogenerate QA reports for the human immunodeficiency virus (HIV) quantitation, hepatitis C virus (HCV) quantitation, and BK virus (BKV) quantitation. Alchemy allowed the user to select a specific timeframe to be analyzed and calculated key QA statistics in real-time, including the average TAT in days, tests falling outside the expected TAT ranges, and test result ranges. Before implementing Alchemy, reporting QA for the HIV, HCV, and BKV quantitation assays took 45-60 min of personnel time per test every month. With Alchemy, that time has decreased to 15 min total per month. Alchemy allowed the user to select specific periods of time and analyzed the TAT data in-depth without the need of extensive manual calculations. Alchemy has significantly decreased the time and the human error associated with QA report generation in our molecular diagnostics laboratory. Other tests will be added to this web-based platform in future updates. This effort shows the utility of informatician-supervised resident/fellow programming projects as learning

Alchemy: A Web 2.0 Real-time Quality Assurance Platform for Human Immunodeficiency Virus, Hepatitis C Virus, and BK Virus Quantitation Assays

PubMed Central

Agosto-Arroyo, Emmanuel; Coshatt, Gina M.; Winokur, Thomas S.; Harada, Shuko; Park, Seung L.

2017-01-01

Background: The molecular diagnostics laboratory faces the challenge of improving test turnaround time (TAT). Low and consistent TATs are of great clinical and regulatory importance, especially for molecular virology tests. Laboratory information systems (LISs) contain all the data elements necessary to do accurate quality assurance (QA) reporting of TAT and other measures, but these reports are in most cases still performed manually: a time-consuming and error-prone task. The aim of this study was to develop a web-based real-time QA platform that would automate QA reporting in the molecular diagnostics laboratory at our institution, and minimize the time expended in preparing these reports. Methods: Using a standard Linux, Nginx, MariaDB, PHP stack virtual machine running atop a Dell Precision 5810, we designed and built a web-based QA platform, code-named Alchemy. Data files pulled periodically from the LIS in comma-separated value format were used to autogenerate QA reports for the human immunodeficiency virus (HIV) quantitation, hepatitis C virus (HCV) quantitation, and BK virus (BKV) quantitation. Alchemy allowed the user to select a specific timeframe to be analyzed and calculated key QA statistics in real-time, including the average TAT in days, tests falling outside the expected TAT ranges, and test result ranges. Results: Before implementing Alchemy, reporting QA for the HIV, HCV, and BKV quantitation assays took 45–60 min of personnel time per test every month. With Alchemy, that time has decreased to 15 min total per month. Alchemy allowed the user to select specific periods of time and analyzed the TAT data in-depth without the need of extensive manual calculations. Conclusions: Alchemy has significantly decreased the time and the human error associated with QA report generation in our molecular diagnostics laboratory. Other tests will be added to this web-based platform in future updates. This effort shows the utility of informatician

Creatinine metabolite, HMH (5-hydroxy-1-methylhydantoin; NZ-419), modulates bradykinin-induced changes in vascular smooth muscle cells.

PubMed

Ienaga, Kazuharu; Sohn, Mimi; Naiki, Mitsuru; Jaffa, Ayad A

2014-06-01

A creatinine metabolite, 5-hydroxy-1-methylhydantoin (HMH: NZ-419), a hydroxyl radical scavenger, has previously been shown to confer renoprotection by inhibiting the progression of chronic kidney disease in rats. In the current study, we demonstrate that HMH modulates the effects of glucose and bradykinin (BK) in vascular smooth muscle cell (VSMC). HMH a novel anti-oxidant drug completely suppressed the expression of B2-kinin receptors (B2KR) in response to high glucose (25 mM) stimulation in VSMC and was also shown to attenuate the effects of BK on VSMC remodeling. HMH inhibited the BK-induced increase in MAPK phosphorylation and attenuated the increase in connective tissue growth factor (CTGF) protein levels in VSMC. These findings suggest that HMH may confer vascular protection against high glucose concentrations and BK-stimulation to ameliorate vascular injury and remodeling through its anti-oxidant properties.

Influence of Ni/Mn ratio on magnetostructural transformation and magnetocaloric effect in Ni48-x Co2Mn38+x Sn12 (x = 0, 1.0, 1.5, 2.0, and 2.5) ferromagnetic shape memory alloys

NASA Astrophysics Data System (ADS)

Shah, Ishfaq Ahmad; Hassan, Najam ul; Rauf, Abdur; Liu, Jun; Gong, Yuanyuan; Xu, Guizhou; Xu, Feng

2017-08-01

Not Available Project supported by the National Natural Science Foundation of China (Grant Nos. 51601092, 51571121, and 11604148), the Fundamental Research Funds for the Central Universities, China (Grant Nos. 30916011344 and 30916011345), Jiangsu Natural Science Foundation for Distinguished Young Scholars, China (Grant No. BK20140035), China Postdoctoral Science Foundation (Grant No. 2016M591851), the Natural Science Foundation of Jiangsu Province, China (Grant Nos. BK20160833 and BK20160829), Qing Lan Project of Jiangsu Province, China, Priority Academic Program Development of Jiangsu Higher Education Institutions, China, and NMG-NJUST Joint Scholarship Program for Ishfaq Ahmad Shah (Student ID: 914116020118).

Nonlinear optical inves

NASA Astrophysics Data System (ADS)

Zidan, M. D.; Arfan, A.; Allahham, A.

2017-03-01

Z-scan technique was used to investigate the nonlinear optical properties of Quinine and 1-(carboxymethyl)-6-methoxy-4-(3-(3-vinylpiperidin-4-yl) propanoyl) quinolin-1-ium chloride (Quinotoxine) salts. The two salts were characterized using UV-visible, FTIR and NMR measurements. The characterization spectra confirm the expected molecular structure of the prepared ;Quinotoxine ; salt. The z-scan measurements were performed with a CW Diode laser at 635 nm wavelength and 26 mW power. The nonlinear absorption coefficient (β), nonlinear refractive index bk [?up][?tjl=1000][?down]?clretain->(n2), the ground-state absorption cross sections bk [?up][?tjl=1000][?down]?clretain->(σg), the excited-state absorption cross sections bk [?up][?tjl=1000][?down]?clretain->(σex) and thermo-optic coefficient of the samples were determined. Our results reveal that the bk [?up][?tjl=1000][?down]?clretain->σex is higher than the bk [?up][?tjl=1000][?down]?clretain->σg indicating that the reverse saturable absorption (RSA) is the dominating mechanism for the observed absorption nonlinearities. The results suggest that this material should be considered as a promising candidate for future optical devices applications.

Effects of nitric oxide on expressions of nitrosocysteine and calcium-activated potassium channels in the supraoptic nuclei and neural lobe of dehydrated rats

PubMed Central

Kadekaro, Massako; Su, Guangxiao; Chu, Rong; Lei, Yongzhong; Li, Junfa; Fang, Li

2007-01-01

Nitric oxide (NO) is an important gas mediator in the signal transduction cascade regulating osmotic function in the hypothalamo-neurohypophysial system. We previously found that increased nitric oxide synthase (NOS) activity in the supraoptic nuclei (SON) and neural lobe following osmotic stimulation and NO could regulate the expression of Ca2+-activated K+ channel (BK channels) protein in the magnocellular system during dehydration. The aim of the current study is to examine the role of NO in the regulation of nitrosocysteine and BK channel protein in the magnocellular system in dehydrated animals. Using Western blot analysis and quantitative immunofluorescent staining study, we found that water deprivation in rats significantly enhanced the expression of nitrosocysteine protein in SON and neural lobes. Immunohistochemistry study indicated that dehydration significantly increased the profiles of SON neurons co-expressing nitrosocysteine with BK-channel protein. Intracerebroventricular administration of L-NAME (an inhibitor of NO synthase) significantly reduced the neuronal profiles of nitrosocysteine, as well as their co-expression with BK-channel in SON of dehydrated rats. However, treatment of sodium nitroprusside (a donor of NO) increased this co-expression. Our results indicate that NO signaling cascade may control the expression of BK channels through the regulation of nitrosocysteine in SON and neural lobe of rats during osmotic regulation. PMID:17098363

Quantification of Human Polyomaviruses JC Virus and BK Virus by TaqMan Quantitative PCR and Comparison to Other Water Quality Indicators in Water and Fecal Samples▿

PubMed Central

McQuaig, Shannon M.; Scott, Troy M.; Lukasik, Jerzy O.; Paul, John H.; Harwood, Valerie J.

2009-01-01

In the United States, total maximum daily load standards for bodies of water that do not meet bacterial water quality standards are set by each state. The presence of human polyomaviruses (HPyVs) can be used as an indicator of human-associated sewage pollution in these waters. We have developed and optimized a TaqMan quantitative PCR (QPCR) assay based on the conserved T antigen to both quantify and simultaneously detect two HPyVs; JC virus and BK virus. The QPCR assay was able to consistently quantify ≥10 gene copies per reaction and is linear over 5 orders of magnitude. HPyVs were consistently detected in human waste samples (57 of 64) and environmental waters with known human fecal contamination (5 of 5) and were not amplified in DNA extracted from 127 animal waste samples from 14 species. HPyV concentrations in sewage decreased 81.2 and 84.2% over 28 days incubation at 25 and 35°C, respectively. HPyVs results were compared to Escherichia coli, fecal coliform, and enterococci concentrations and the presence of three other human-associated microbes: Bacteroidetes, Methanobrevibacter smithii, and adenovirus. HPyVs were the most frequently detected of these in human and contaminated environmental samples and were more human specific than the Bacteroidetes (HF183) or M. smithii. HPyVs and M. smithii more closely mimicked the persistence of adenovirus in sewage than the other microbes. The use of this rapid and quantitative assay in water quality research could help regulatory agencies to identify sources of water pollution for improved remediation of contaminated waters and ultimately protect humans from exposure to pathogens. PMID:19346361

Catalysis-dependent stabilization of Bre1 fine-tunes histone H2B ubiquitylation to regulate gene transcription

PubMed Central

Wozniak, Glenn G.

2014-01-01

Monoubiquitylation of histone H2B on Lys123 (H2BK123ub1) plays a multifaceted role in diverse DNA-templated processes, yet the mechanistic details by which this modification is regulated are not fully elucidated. Here we show in yeast that H2BK123ub1 is regulated in part through the protein stability of the E3 ubiquitin ligase Bre1. We found that Bre1 stability is controlled by the Rtf1 subunit of the polymerase-associated factor (PAF) complex and through the ability of Bre1 to catalyze H2BK123ub1. Using a domain in Rtf1 that stabilizes Bre1, we show that inappropriate Bre1 levels lead to defects in gene regulation. Collectively, these data uncover a novel quality control mechanism used by the cell to maintain proper Bre1 and H2BK123ub1 levels, thereby ensuring proper control of gene expression. PMID:25085417

Electric energy savings from new technologies. Revision 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harrer, B.J.; Kellogg, M.A.; Lyke, A.J.

1986-09-01

Purpose of the report is to provide information about the electricity-saving potential of new technologies to OCEP that it can use in developing alternative long-term projections of US electricity consumption. Low-, base-, and high-case scenarios of the electricity savings for 10 technologies were prepared. The total projected annual savings for the year 2000 for all 10 technologies were 137 billion kilowatt hours (BkWh), 279 BkWh, and 470 BkWh, respectively, for the three cases. The magnitude of these savings projections can be gauged by comparing them to the Department's reference case projection for the 1985 National Energy Policy Plan. In themore » Department's reference case, total consumption in 2000 is projected to be 3319 BkWh. Because approximately 75% of the base-case estimate of savings are already incorporated into the reference projection, only 25% of the savings estimated here should be subtracted from the reference projection for analysis purposes.« less

Quantum transition probabilities during a perturbing pulse: Differences between the nonadiabatic results and Fermi's golden rule forms

NASA Astrophysics Data System (ADS)

Mandal, Anirban; Hunt, Katharine L. C.

2018-05-01

For a perturbed quantum system initially in the ground state, the coefficient ck(t) of excited state k in the time-dependent wave function separates into adiabatic and nonadiabatic terms. The adiabatic term ak(t) accounts for the adjustment of the original ground state to form the new ground state of the instantaneous Hamiltonian H(t), by incorporating excited states of the unperturbed Hamiltonian H0 without transitions; ak(t) follows the adiabatic theorem of Born and Fock. The nonadiabatic term bk(t) describes excitation into another quantum state k; bk(t) is obtained as an integral containing the time derivative of the perturbation. The true transition probability is given by |bk(t)|2, as first stated by Landau and Lifshitz. In this work, we contrast |bk(t)|2 and |ck(t)|2. The latter is the norm-square of the entire excited-state coefficient which is used for the transition probability within Fermi's golden rule. Calculations are performed for a perturbing pulse consisting of a cosine or sine wave in a Gaussian envelope. When the transition frequency ωk0 is on resonance with the frequency ω of the cosine wave, |bk(t)|2 and |ck(t)|2 rise almost monotonically to the same final value; the two are intertwined, but they are out of phase with each other. Off resonance (when ωk0 ≠ ω), |bk(t)|2 and |ck(t)|2 differ significantly during the pulse. They oscillate out of phase and reach different maxima but then fall off to equal final values after the pulse has ended, when ak(t) ≡ 0. If ωk0 < ω, |bk(t)|2 generally exceeds |ck(t)|2, while the opposite is true when ωk0 > ω. While the transition probability is rising, the midpoints between successive maxima and minima fit Gaussian functions of the form a exp[-b(t - d)2]. To our knowledge, this is the first analysis of nonadiabatic transition probabilities during a perturbing pulse.

Hypotensive effects of hemopressin and bradykinin in rabbits, rats and mice. A comparative study.

PubMed

Blais, Paul-André; Côté, Jérôme; Morin, Josée; Larouche, Annie; Gendron, Gabrielle; Fortier, Audrey; Regoli, Domenico; Neugebauer, Witold; Gobeil, Fernand

2005-08-01

Hemopressin is a novel vasoactive nonapeptide derived from hemoglobin's alpha-chain as recently reported by Rioli et al. [Rioli V, Gozzo FC, Heimann AS, Linardi A, Krieger JE, Shida CS, et al. Novel natural peptide substrates for endopeptidase 24.15, neurolysin, and angiotensin-converting enzyme. J Biol Chem 2003;278(10):8547-55]. In anesthetized male Wistar rats, this peptide exhibited hypotensive actions similar to those of bradykinin (BK) when administered intravenously (i.v.), and was found to be metabolized both in vitro and in vivo by several peptidases, including the angiotensin-converting enzyme (ACE). In this study, these findings were expanded upon by examining: (i) the degradation kinetics following incubation with ACE purified from rabbit lung and (ii) the blood pressure lowering effects of HP and BK injected i.v. or intra-arterially (i.a.) in male rabbits, rats, and mice. Our findings demonstrate that, in vitro, HP and BK are both degraded by ACE, but at different velocity rates. Furthermore, both HP and BK induced transient hypotension in all animals tested, although the responses to HP relative to the administration sites were significantly lower (by 10-100-fold) on an equimolar basis compared to those of BK. In rabbits, the decrease of blood pressure induced by HP (10-100 nmol/kg) did not differ whether it was administered i.v. or i.a., suggesting an absence of pulmonary/cardiac inactivation in contrast to BK (0.1-1 nmol/kg). The in vivo effect of HP was significantly potentiated in rabbits immunostimulated with bacterial lipopolysaccharide (LPS), but was unaffected by both the B2 receptor antagonist HOE 140 (0.1 micromol/kg) and captopril (100 microg/kg), contrary to BK. Therefore, HP acts as a weak hypotensive mediator, which does not activate kinin B2 receptors, but uses a functional site and/or signaling paths appearing to be up-regulated by LPS.

Primary BK virus (BKV) infection due to possible BKV transmission during bone marrow transplantation is not the major cause of hemorrhagic cystitis in transplanted children.

PubMed

Bogdanovic, G; Priftakis, P; Taemmeraes, B; Gustafsson, A; Flaegstad, T; Winiarski, J; Dalianis, T

1998-11-01

In allogeneic bone marrow transplanted (BMT) patients BK virus (BKV) reactivation has been associated with haemorrhagic cystitis (HC). However, it is far from obvious which patients will develop HC, since BKV, a human polyomavirus, is ubiquitious and infects children at an early age. To investigate if a primary BKV infection, as such or possibly due to transmission of BKV by the marrow graft during BMT, was correlated to the development of HC, 45 children were followed for possible BKV seroconversion and development of HC at different time points after BMT. Serum samples were collected from the 45 allogeneic BMT children and their donors before transplantation, and from the patients at 3, 6 and 12 months after BMT. These sera were analysed for the presence of specific antibodies towards BKV by hemagglutination inhibition (HAI) and by IgG- and IgM-class specific enzyme linked immunosorbent (ELISA) assays. Twelve of the 45 BMT children had a documented episode of HC or hematuria. All patients and 98% of the donors were HAI positive before BMT, while with ELISA 87% of the patients and 84% of the donors were positive. Moreover, most HC and hematuria children (11/12) were seropositive with both assays before BMT, making it impossible to investigate possible BKV transmission through the bone marrow graft during BMT by serology. Still, serological changes such as ELISA seroconversion, IgM antibodies and/or HAI titer increases were significantly (p=0.016) more common in patients with HC (58%) than without HC (24%), but these changes occured mainly after HC symptomatology had already resolved. However, there was a near significant difference (p=0.053) in BKV seroprevalence by ELISA among the donors of patients with HC or hematuria (67%) as compared to the donors (91%) of patients without HC.

Advanced Human Factors Engineering Tool Technologies.

DTIC Science & Technology

1988-03-01

charger/ AC adapter immersible probe air temperature probe surface temperature probe . * Sling psychrometer , MSA or Taylor 1328A * Aspirating... psychrometer , Model PP-100 or CP-147, Psychro-Dyne * Wet-bulb-heat-stress monitor, Model B&K 1219, Briel & Kjaer Transducer, Model B&K MM 0030 (3 each), Brijel

Long-Term Antihyperalgesic and Opioid-Sparing Effects of 5-Day Ketamine and Morphine Infusion ("Burst Ketamine") in Diabetic Neuropathic Rats.

PubMed

Mak, Plato; Broadbear, Jillian H; Kolosov, Anton; Goodchild, Colin S

2015-09-01

"Burst ketamine" (BK) is the long-term infusion of subanesthetic ketamine in combination with an opioid. It is used clinically with mixed success to provide long-term pain relief and improve opioid response in patients. BK has not been simulated preclinically, therefore, its effectiveness was investigated in an animal model of neuropathic pain--streptozotocin-induced diabetic neuropathy. Diabetic neuropathic rats were randomized to receive a subcutaneous infusion of ketamine 20 mg/kg/day plus morphine 20 mg/kg/day (BK), either drug alone at the same dose, or sham treatment. Drugs were administered continuously over 5 days via osmotic minipump. Antihyperalgesic effects and antinociceptive responsiveness to morphine (0.625-10 mg/kg, i.p.) were assessed at 2, 4, 6, and 12 weeks post-treatment using paw withdrawal latency (PWL) from noxious heat (thermal hyperalgesia) and mechanical touch (tactile allodynia). Antihyperalgesic effects with significant increases in PWL from noxious heat occurred following BK and ketamine-only infusion, persisting 12 and 4 weeks, respectively. Opioid-sparing effects from noxious heat with increased sensitivity to morphine analgesia also occurred for 6 weeks after BK and 2 weeks after ketamine treatment; acute treatment with the maximum nonsedating dose of morphine (5 mg/kg) produced an antinociceptive effect in these two groups, but not in sham-treated rats. In morphine-only infusion rats, hyperalgesia and opioid insensitivity were both increased. This is the first preclinical study to use a model of neuropathic pain to demonstrate the utility of the BK procedure for delivering a long-lasting reduction in hyperalgesia and improved antinociceptive responsiveness to opioids. Wiley Periodicals, Inc.

Bradykinin Promotes Cell Proliferation, Migration, Invasion, and Tumor Growth of Gastric Cancer Through ERK Signaling Pathway.

PubMed

Wang, Guojun; Sun, Junfeng; Liu, Guanghui; Fu, Yang; Zhang, Xiefu

2017-12-01

Bradykinin (BK) has been reported to be involved in the progression of diverse types of cancer. In the present study, we investigated the possible role of BK in cell proliferation, migration, invasion, and tumor growth of gastric cancer (GC). Cell proliferation was evaluated by MTT assays. Cell migration and invasion were assessed by Transwell assays. Tumor growth of nude mice was detected by establishing subcutaneous xenograft tumor model. Silencing of bradykinin B1 receptor (B1R) and the bradykinin B2 receptor (B2R) was performed by transfecting cells with si-B1R and si-B2R, respectively. The protein expression levels of phospho-ERK1/2 (p-ERK1/2), matrix metalloproteinase (MMP)-2, MMP-9, and E-Cadherin were examined by Western blot. Data revealed that BK promoted cell proliferation, migration, invasion, and the in vivo tumor growth of GC cells SGC-7901 and HGC-27. Furthermore, BK elevated the protein levels of p-ERK1/2, MMP-2, and MMP-9, but reduced E-Cadherin. In addition, by repressing B2R using si-B2R or inhibiting ERK signaling pathway using PD98059, BK-mediated promotion of cell proliferation, migration, and invasion and upregulation of p-ERK1/2, MMP-2/9, as well as downregulation of E-Cadherin were attenuated. Taken together, the present study demonstrated that BK promoted cell proliferation, migration, invasion, and tumor growth by binding to B2R via ERK signaling pathway. Our findings may provide promising options for the further treatment of GC. J. Cell. Biochem. 118: 4444-4453, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Functional and molecular characterization of kinin B1 and B 2 receptors in human bladder cancer: implication of the PI3Kγ pathway.

PubMed

Sgnaolin, V; Pereira, T C B; Bogo, M R; Zanin, R; Battastini, A M O; Morrone, F B; Campos, M M

2013-08-01

Kinins and their receptors have been recently implicated in cancer. Using functional and molecular approaches, we investigated the relevance of kinin B1 and B2 receptors in bladder cancer. Functional studies were conducted using bladder cancer cell lines, and human biopsies were employed for molecular studies. Both B1 des-Arg(9)-BK and B2 BK receptor agonists stimulated the proliferation of grade 3-derived T24 bladder cancer cells. Furthermore, treatment with B1 and B2 receptor antagonists (SSR240612 and HOE140) markedly inhibited the proliferation of T24 cells. Only higher concentrations of BK increased the proliferation of the grade 1 bladder cancer cell line RT4, while des-Arg(9)-BK completely failed to induce its proliferation. Real-time PCR revealed that the mRNA expression of kinin receptors, particularly B1 receptors, was increased in T24 cells relative to RT4 cells. Data from bladder cancer human biopsies revealed that B1 receptor expression was increased in all tumor samples and under conditions of chronic inflammation. We also show novel evidence demonstrating that the pharmacological inhibition of PI3Kγ (phosphatidylinositol 3-kinase) with AS252424, concentration-dependently reduced T24 cell proliferation induced by BK or des-Arg(9)-BK. Finally, the incubation of T24 cells with kinin agonists led to a marked activation of the PI3K/AKT and ERK 1/2 signaling pathways, whereas p38 MAP kinase remained unaffected. Kinin receptors, especially B1 receptors, appear to be implicated in bladder cancer progression. It is tempting to suggest that selective kinin antagonists might represent potential alternative therapies for bladder cancer.

Birth-Kindergarten Licensure Graduates' Perceptions of Their Current Practices and Pre-Service Preparation Relative to Individualization Strategies for Young Children

ERIC Educational Resources Information Center

Gillis, Margaret C.

2011-01-01

The purpose of this study was to examine the current practices and pre-service preparation of recent graduates of North Carolina Birth-Kindergarten (B-K) teacher licensure programs related to individualizing curriculum and instruction for children. Participants were 142 individuals who graduated from B-K licensure programs in four-year…

Depletion of intracellular calcium stores facilitates the influx of extracellular calcium in platelet derived growth factor stimulated A172 glioblastoma cells.

PubMed

Vereb, G; Szöllösi, J; Mátyus, L; Balázs, M; Hyun, W C; Feuerstein, B G

1996-05-01

Calcium signaling in non-excitable cells is the consequence of calcium release from intracellular stores, at times followed by entry of extracellular calcium through the plasma membrane. To study whether entry of calcium depends upon the level of saturation of intracellular stores, we measured calcium channel opening in the plasma membrane of single confluent A172 glioblastoma cells stimulated with platelet derived growth factor (PDGF) and/or bradykinin (BK). We monitored the entry of extracellular calcium by measuring manganese quenching of Indo-1 fluorescence. PDGF raised intracellular calcium concentration ([Ca2+]i) after a dose-dependent delay (tdel) and then opened calcium channels after a dose-independent delay (tch). At higher doses (> 3 nM), BK increased [Ca2+]i after a tdel approximately 0 s, and tch decreased inversely with both dose and peak [Ca2+]i. Experiments with thapsigargin (TG), BK, and PDGF indicated that BK and PDGF share intracellular Ca2+ pools that are sensitive to TG. When these stores were depleted by treatment with BK and intracellular BAPTA, tdel did not change, but tch fell to almost 0 s in PDGF stimulated cells, indicating that depletion of calcium stores affects calcium channel opening in the plasma membrane. Our data support the capacitative model for calcium channel opening and the steady-state model describing quantal Ca2+ release from intracellular stores.

Risk Factors for Haemorrhagic Cystitis in Paediatric Allogeneic Hematopoietic Stem Cell Transplant Recipients

PubMed Central

Hayden, RT; Gu, Z; Liu, Wei; Lovins, R; Kasow, K; Woodard, P; Srivistava, K; Leung, W

2015-01-01

Haemorrrhagic cystitis (HC) results in significant morbidity among hematopoietic stem cell transplant (HSCT) recipients. Several potential causes for HC have been postulated, including viral infection, but definitive evidence is lacking, particularly in paediatric HSCT patients. Ninety paediatric HSCT recipients were prospectively tested on a weekly basis for adenovirus and BK virus by quantitative real-time PCR in blood and urine samples. Results were correlated with the occurrence of grade II-IV HC. The odds ratio (OR) of HC (95% CI) for BK virus ≥ 1× 109 copies/mL of urine was 7.39 (1.52, 35.99), with a p-value of 0.013. Those with aGvHD also had higher odds of developing HC, with an OR of 5.34. Given a 20% prevalence rate of HC, positive and negative predictive values of 29% and 95% were seen with a cutoff of 109 copies/mL. BK viremia did not reach significance as a risk factor for development of HC (p=0.06). Only 8 patients showed adenoviruria and 7 showed adenoviremia; all had low viral loads and four had no evidence of HC. HC in paediatric HSCT is correlated most strongly to elevated urinary viral load of BK virus and to aGVHD, but less strongly to BK viremia. PMID:25648430

Endogenous bradykinin activates ischaemically sensitive cardiac visceral afferents through kinin B2 receptors in cats

PubMed Central

Tjen-A-Looi, Stephanie C; Pan, Hui-Lin; Longhurst, John C

1998-01-01

Activity of ischaemically sensitive cardiac visceral afferents during myocardial ischaemia induces both angina and cardiovascular reflexes. Increased production of bradykinin (BK) and cyclo-oxygenase products (i.e. prostaglandins (PGs)) occurs during myocardial ischaemia. However, the role of these agents in activation of ischaemically sensitive cardiac afferents has not been established. The present study tested the hypothesis that BK produced during ischaemia activates cardiac afferents through kinin B2 receptors. Single-unit activity of cardiac afferents innervating the left ventricle was recorded from the left thoracic sympathetic chain (T1–T4) of anaesthetized cats. Ischaemically sensitive cardiac afferents were identified according to their response to 5 min of myocardial ischaemia. The mechanism of BK in activation of ischaemically sensitive cardiac afferents was determined by injection of BK (1 μg kg−1 i.a.), des-Arg9-BK (1 μg kg−1 i.a., a specific kinin B1 receptor agonist), kinin B2 receptor antagonists: HOE140 (30 μg kg−1 i.v.) and NPC-17731 (40 μg kg−1 i.v.), cyclo-oxygenase inhibition with indomethacin (5 mg kg−1 i.v.) and NPC-17731 (40 μg kg−1 i.v.) after pretreatment with indomethacin (5 mg kg−1 i.v.). We observed that BK increased the discharge rate of all eleven ischaemically sensitive cardiac afferents from 0.39 ± 0.12 to 1.47 ± 0.37 impulses s−1 (P < 0.05). Conversely, des-Arg9-BK did not significantly increase the activity of eleven ischaemically sensitive fibres (0.58 ± 0.02 vs. 0.50 ± 0.18 impulses s−1). HOE140 significantly attenuated the response of twelve afferents to ischaemia (0.61 ± 0.22 to 1.85 ± 0.5 vs. 0.53 ± 0.16 to 1.09 ± 0.4 impulses s−1). NPC-17731, another kinin B2 receptor antagonist, had similar inhibitory effects on six other ischaemically sensitive cardiac afferents (0.35 ± 0.14 to 1.19 ± 0.29 vs. 0.22 ± 0.08 to 0.23 ± 0.07 impulses s−1). Indomethacin significantly reduced the

Elevated K+ channel activity opposes vasoconstrictor response to serotonin in cerebral arteries of the Fawn Hooded Hypertensive rat.

PubMed

Pabbidi, Mallikarjuna R; Roman, Richard J

2017-01-01

Previous studies suggest that middle cerebral arteries (MCAs) of Fawn Hooded Hypertensive (FHH) rats exhibit impaired myogenic response and introgression of a small region of Brown Norway chromosome 1 containing 15 genes restored the response in FHH.1 BN congenic rat. The impaired myogenic response in FHH rats is associated with an increase in the activity of the large conductance potassium (BK) channel in vascular smooth muscle cells (VSMCs). The present study examined whether the increased BK channel function in FHH rat alters vasoconstrictor response to serotonin (5-HT). Basal myogenic tone and spontaneous myogenic response of the MCA was attenuated by about twofold and about fivefold, respectively in FHH compared with FHH.1 BN rats. 5-HT (0.1 μM)-mediated vasoconstriction was about twofold lower, and inhibition of the BK channel increased the vasoconstrictor response by about threefold in FHH compared with FHH.1 BN rats. 5-HT (3 μM) decreased BK channel and spontaneous transient outward currents in VSMCs isolated from FHH.1 BN but had no effect in FHH rats. 5-HT significantly depolarized the membrane potential in MCAs of FHH.1 BN than FHH rats. Blockade of the BK channel normalized 5-HT-induced depolarization in MCAs of FHH rats. The 5-HT-mediated increase in cytosolic calcium concentration was significantly reduced in plateau phase in the VSMCs of FHH relative to FHH.1 BN rats. These findings suggest that sequence variants in the genes located in the small region of FHH rat chromosome 1 impairs 5-HT-mediated vasoconstriction by decreasing its ability to inhibit BK channel activity, depolarize the membrane and blunt the rise in cytosolic calcium concentration. Copyright © 2017 the American Physiological Society.

Panicolytic-like action of bradykinin in the dorsal periaqueductal gray through μ-opioid and B2-kinin receptors.

PubMed

Sestile, Caio César; Maraschin, Jhonatan Christian; Gama, Vanessa Scalco; Zangrossi, Hélio; Graeff, Frederico Guilherme; Audi, Elisabeth Aparecida

2017-09-01

A wealth of evidence has shown that opioid and kinin systems may control proximal defense in the dorsal periaqueductal gray matter (dPAG), a critical panic-associated area. Studies with drugs that interfere with serotonin-mediated neurotransmission suggest that the μ-opioid receptor (MOR) synergistically interacts with the 5-HT 1A receptor in the dPAG to inhibit escape, a panic-related behavior. A similar inhibitory effect has also been reported after local administration of bradykinin (BK), which is blocked by the non-selective opioid receptor antagonist naloxone. The latter evidence, points to an interaction between BK and opioids in the dPAG. We further explored the existence of this interaction through the dPAG electrical stimulation model of panic. We also investigated whether intra-dPAG injection of captopril, an inhibitor of the angiotensin-converting enzyme (ACE) that also degrades BK, causes a panicolytic-like effect. Our results showed that intra-dPAG injection of BK inhibited escape performance in a dose-dependent way, and this panicolytic-like effect was blocked by the BK type 2 receptor (B2R) antagonist HOE-140, and by the selective MOR antagonist CTOP. Conversely, the panicolytic-like effect caused by local administration of the selective MOR agonist DAMGO was antagonized by pre-treatment with either CTOP or HOE-140, indicating cross-antagonism between MOR and B2R. Finally, intra-dPAG injection of captopril also impaired escape in a dose-dependent way, and this panicolytic-like effect was blocked by pretreatment with HOE-140, suggesting mediation by endogenous BK. The panicolytic-like effect of captopril indicates that the use of ACE inhibitors in the clinical management of panic disorder may be worth exploring. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of indigestible carbohydrates in barley on glucose metabolism, appetite and voluntary food intake over 16 h in healthy adults.

PubMed

Johansson, Elin V; Nilsson, Anne C; Östman, Elin M; Björck, Inger M E

2013-04-11

Recent knowledge in animals suggests that gut microbial metabolism may affect host metabolism, including appetite regulating hormones. The aim of the present study was to evaluate the potential effects of a whole grain barley kernel product, rich in intrinsic indigestible carbohydrates (dietary fibre and resistant starch), on markers of metabolism and appetite regulation in healthy subjects. Boiled barley kernels (BK) or white wheat bread (WWB; reference) were provided as late evening meals to 19 young adults in random order using a cross-over design. During subsequent ad libitum standardized breakfast and lunch meals (10.5-16 h), blood was collected for analysis of glucose, plasma insulin, adiponectin, ghrelin, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), serum free fatty acids (FFA) and interleukin (IL)-6. In addition, appetite sensations, voluntary energy intake and breath H2 were determined. BK as evening meal increased plasma GLP-1 at fasting (P < 0.05) and during the experimental day (P < 0.01) compared with WWB. In addition the BK evening meal decreased fasting serum FFA (P < 0.05) and tended to decrease fasting serum IL-6 (P = 0.06). At lunch, preceded by BK evening meal, voluntary energy intake was decreased (P < 0.05) when compared to WWB evening meal. The BK evening meal decreased incremental blood glucose area (P < 0.01), promoted higher breath H2 (P < 0.001), maintained adiponectin concentrations (P < 0.05) and reduced perceived hunger (P < 0.05) during 10.5-16 h after the meal. The results indicate that the BK evening meal, facilitate glucose regulation, increase the release of GLP-1, reduce subsequent energy intake while at the same time decreasing hunger over 2 subsequent meals, and reduce fasting FFA the subsequent morning, possibly mediated through gut microbial fermentation of the indigestible carbohydrates.

Plasma Kallikrein-Kinin system mediates immune-mediated renal injury in trichloroethylene-sensitized mice.

PubMed

Wang, Hui; Zhang, Jia-Xiang; Ye, Liang-Ping; Li, Shu-Long; Wang, Feng; Zha, Wan-Sheng; Shen, Tong; Wu, Changhao; Zhu, Qi-Xing

2016-07-01

Trichloroethylene (TCE) is a major environmental pollutant. An immunological response is a newly-recognized mechanism for TCE-induced kidney damage. However, the role of the plasma kallikrein-kinin system (KKS) in immune-mediated kidney injury has never been examined. This study aimed to explore the role of the key components of the KKS, i.e. plasma kallikrein (PK), bradykinin (BK) and its receptors B1R and B2R, in TCE-induced kidney injury. A mouse model of skin sensitization was used to explore the mechanism of injury with or without a PK inhibitor PKSI. Kidney function was evaluated by measuring blood urea nitrogen (BUN) and creatinine (Cr) in conjunction with histopathologic characterization. Plasma BK was determined by ELISA; Renal C5b-9 membrane attack complex was evaluated by immunohistochemistry. Expression of BK and PK in the kidney was detected by immunofluorescence. mRNA and protein levels of B1R and B2R were assessed by real-time qPCR and Western blot. As expected, numerous inflammatory cell infiltration and tubular epithelial cell vacuolar degeneration were observed in TCE-sensitized mice. Moreover, serum BUN and Cr and plasma BK were increased. In addition, deposition of BK, PK and C5b-9 were observed and B1R and B2R mRNA and proteins levels were up-regulated. Pre-treatment with PKSI, a highly selective inhibitor of PK, alleviated TCE-induced renal damage. In addition, PKSI attenuated TCE-induced up-regulation of BK, PK and its receptors and C5b-9. These results provided the first evidence that activation of the KKS contributed to immune-mediated renal injury induced by TCE and also helped to identify the KKS as a potential therapeutic target for mitigating chemical sensitization-induced renal damage.

Demonstration of extrapulmonary activity of angiotensin converting enzyme in intact tissue preparations.

PubMed

Lembeck, F; Griesbacher, T; Eckhardt, M

1990-05-01

1. The activity of angiotensin converting enzyme (ACE) has been studied on functional parameters of intact isolated preparations of extrapulmonary tissues. The conversion of angiotensin I (A I) to angiotensin II (A II) and the cleavage of bradykinin (BK) were used as indicators of ACE activity. Captopril was employed as a specific inhibitor of ACE. 2. Captopril augmented the BK-induced contractions of the rat isolated uterus, the BK- and substance P-induced contractions of the guinea-pig ileum, and the BK-induced venoconstriction in the isolated perfused ear of the rabbit. Degradation of BK by ACE was calculated to be 52% in the rat uterus and 75% in the rabbit perfused ear. 3. Captopril inhibited the A I-induced contractions of the rat isolated colon, the A I-induced vasoconstriction in the isolated perfused ear of the rabbit and the rise in blood pressure induced by i.a. injections of A I in pithed rats. Conversion of A I to A II was calculated to be 13% in the rat colon and 26% in the rabbit perfused ear. 4. From estimations of the A II activity (bioassay on the rat colon) in the effluent of the perfused ear of the rabbit after injections of A I into the arterial inflow cannula it was calculated that approximately one tenth of A I was converted to A II during a single passage through the ear (less than 15 s). 5. The present experiments suggest that the high activity of ACE in endothelium of blood vessels of extrapulmonary tissues may provide an additional (endothelium-dependent) local vasoconstrictor mechanism by the rapid formation of A II and inactivation of BK. The ACE activity in non-vascular smooth muscles, other than those of blood vessels, may also affect the physiological functions of these tissues.

Melatonin mediates vasodilation through both direct and indirect activation of BKCa channels.

PubMed

Zhao, T; Zhang, H; Jin, C; Qiu, F; Wu, Y; Shi, L

2017-10-01

Melatonin, synthesized primarily by the pineal gland, is a neuroendocrine hormone with high membrane permeability. The vascular effects of melatonin, including vasoconstriction and vasodilation, have been demonstrated in numerous studies. However, the mechanisms underlying these effects are not fully understood. Large-conductance Ca 2+ -activated K + (BK Ca ) channels are expressed broadly on smooth muscle cells and play an important role in vascular tone regulation. This study explored the mechanisms of myocyte BK Ca channels and endothelial factors underlying the action of melatonin on the mesenteric arteries (MAs). Vascular contractility and patch-clamp studies were performed on myocytes of MAs from Wistar rats. Melatonin induced significant vasodilation on MAs. In the presence of N ω -nitro-l-arginine methyl ester (l-NAME), a potent endothelial oxide synthase (eNOS) inhibitor, melatonin elicited concentration-dependent relaxation, with lowered pIC 50 The effect of melatonin was significantly attenuated in the presence of BK Ca channel blocker iberiotoxin or MT1/MT2 receptor antagonist luzindole in both (+) l-NAME and (-) l-NAME groups. In the (+) l-NAME group, iberiotoxin caused a parallel rightward shift of the melatonin concentration-relaxation curve, with pIC 50 lower than that of luzindole. Both inside-out and cell-attached patch-clamp recordings showed that melatonin significantly increased the open probability, mean open time and voltage sensitivity of BK Ca channels. In a cell-attached patch-clamp configuration, the melatonin-induced enhancement of BK Ca channel activity was significantly suppressed by luzindole. These findings indicate that in addition to the activation of eNOS, melatonin-induced vasorelaxation of MAs is partially attributable to its direct (passing through the cell membrane) and indirect (via MT1/MT2 receptors) activation of the BK Ca channels on mesenteric arterial myocytes. © 2017 Society for Endocrinology.

Chandelier Illumination for Descemet Membrane Endothelial Keratoplasty

PubMed Central

Hayashi, Takahiko; Yuda, Kentaro; Tsuchiya, Ayako; Oyakawa, Itaru; Mizuki, Nobuhisa; Kato, Naoko

2017-01-01

Purpose: To describe a simple technique that uses posterior chandelier illumination during Descemet membrane endothelial keratoplasty in cases of severe bullous keratopathy (BK). Methods: Five eyes of 4 patients with advanced BK undergoing Descemet membrane endothelial keratoplasty were retrospectively analyzed. The pupil of the host eye was not treated with mydriatic or miotic agents. The chandelier illuminator was inserted transconjunctivally into the vitreous cavity from the pars plana. Results: In all eyes, BK was secondary to laser iridotomy, which was performed for prevention or treatment of angle closure glaucoma. The implanted graft was clearly confirmed in the anterior chamber using activated chandelier illumination. The graft was immediately attached to the host cornea, with eventual healing of BK in all eyes. No complication involving insertion or removal of the 25-gauge trocar and the chandelier illuminator was observed. No vision-threatening complication was observed in any of the 5 eyes. Conclusions: The chandelier illuminator provided good visibility of the anterior chamber and enhanced the safety of surgery by preventing formation of an inverted graft. PMID:28644235

Inhibition of Large-Conductance Ca2+-Activated K+ Channels by Nanomolar Concentrations of Ag+S⃞

PubMed Central

Xia, Xiaoming; Lingle, Christopher J.

2010-01-01

Silver has been widely used in various medical products because of its antibacterial properties. However, there is only limited information concerning silver-related cytotoxicity. In this study we show that Ag+ at low nanomolar concentrations (<10 nM) strongly inhibits the activity of large-conductance Ca2+-activated K+ channels (BK) (Slo1), a widely expressed and physiologically important potassium channel. The Ag+ inhibition is caused by irreversible modification on cytosolically accessible parts of the BK channel. At least four intracellular cysteines are involved in this process. In addition, at least one of these key cysteines is not accessible to the bulkier thiolate-active reagent [2-(trimethylammonium)ethyl] methanethiosulfonate bromide. One of the cysteine-less constructs generated in this study shows gating properties similar to wild-type BK channel but with much lower Ag+ sensitivity, in which the Ag+ modification rate was decreased by approximately 20-fold. The results from the present study suggest a possible contribution of BK channel inhibition to the cytotoxicity of Ag+ in humans and other species. PMID:20729303

The use of endoillumination probe-assisted Descemet membrane endothelial keratoplasty for bullous keratopathy secondary to argon laser iridotomy

PubMed Central

Kobayashi, Akira; Yokogawa, Hideaki; Yamazaki, Natsuko; Masaki, Toshinori; Sugiyama, Kazuhisa

2015-01-01

Purpose To report the first case of Descemet membrane endothelial keratoplasty (DMEK) for bullous keratopathy (BK) secondary to argon laser iridotomy (ALI). Patient A 71-year-old woman presented with decreased visual acuity in her right eye due to BK secondary to ALI that was performed 10 years prior. Results Phacosurgery was performed first, followed by successful DMEK 4 months later. A DMEK shooter was used for donor insertion, which allowed for a stable anterior chamber during donor insertion, even when the anterior chamber was quite shallow. Also, removal of edematous epithelial cells and endoillumination probe-assisted DMEK was quite useful to visualize DMEK graft on the background of the dark brown iris seen in Asian eyes. The patient’s best corrected visual acuity rapidly increased from 20/200 to 25/20 after 1 month, with complete resolution of corneal edema. Conclusion We reported the first successful DMEK case for BK secondary to ALI. The use of a DMEK shooter for donor insertion and endoillumination assistance to visualize the DMEK graft was a useful technique for BK secondary to ALI. PMID:25609910

Threading the biophysics of mammalian Slo1 channels onto structures of an invertebrate Slo1 channel

PubMed Central

2017-01-01

For those interested in the machinery of ion channel gating, the Ca2+ and voltage-activated BK K+ channel provides a compelling topic for investigation, by virtue of its dual allosteric regulation by both voltage and intracellular Ca2+ and because its large-single channel conductance facilitates detailed kinetic analysis. Over the years, biophysical analyses have illuminated details of the allosteric regulation of BK channels and revealed insights into the mechanism of BK gating, e.g., inner cavity size and accessibility and voltage sensor-pore coupling. Now the publication of two structures of an Aplysia californica BK channel—one liganded and one metal free—promises to reinvigorate functional studies and interpretation of biophysical results. The new structures confirm some of the previous functional inferences but also suggest new perspectives regarding cooperativity between Ca2+-binding sites and the relationship between voltage- and Ca2+-dependent gating. Here we consider the extent to which the two structures explain previous functional data on pore-domain properties, voltage-sensor motions, and divalent cation binding and activation of the channel. PMID:29025867

Design and synthesis of novel sulfonamide-containing bradykinin hB2 receptor antagonists. 2. Synthesis and structure-activity relationships of alpha,alpha-cycloalkylglycine sulfonamides.

PubMed

Fattori, Daniela; Rossi, Cristina; Fincham, Christopher I; Caciagli, Valerio; Catrambone, Fernando; D'Andrea, Piero; Felicetti, Patrizia; Gensini, Martina; Marastoni, Elena; Nannicini, Rossano; Paris, Marielle; Terracciano, Rosa; Bressan, Alessandro; Giuliani, Sandro; Maggi, Carlo A; Meini, Stefania; Valenti, Claudio; Quartara, Laura

2007-02-08

Recently we reported on the design and synthesis of a novel class of selective nonpeptide bradykinin (BK) B2 receptor antagonists (J. Med. Chem. 2006, 3602-3613). This work led to the discovery of MEN 15442, an antagonist with subnanomolar affinity for the human B2 receptor (hB2R), which also displayed significant and prolonged activity in vivo (for up to 210 min) against BK-induced bronchoconstriction in the guinea-pig at a dose of 300 nmol/kg (it), while demonstrating only a slight effect on BK-induced hypotension. Here we describe the further optimization of this series of compounds aimed at maximizing the effect on bronchoconstriction and minimizing the effect on hypotension, with a view to developing topically delivered drugs for airway diseases. The work led to the discovery of MEN 16132, a compound which, after intratracheal or aerosol administration, inhibited, in a dose-dependent manner, BK-induced bronchoconstricton in the airways, while showing minimal systemic activity. This compound was selected as a preclinical candidate for the topical treatment of airway diseases involving kinin B2 receptor stimulation.

Carbon buffer layers for smoothing superpolished glass surfaces as substrates for molybdenum /silicon multilayer soft-x-ray mirrors.

PubMed

Stock, H J; Hamelmann, F; Kleineberg, U; Menke, D; Schmiedeskamp, B; Osterried, K; Heidemann, K F; Heinzmann, U

1997-03-01

Zerodur and BK7 glass substrates (developed by Fa. Glaswerke Schott, D-55014 Mainz, Germany) from Carl Zeiss Oberkochen polished to a standard surface roughness of varsigma = 0.8 nm rms were coated with a C layer by electron-beam evaporation in the UHV. The roughness of the C-layer surfaces is reduced to 0.6 nm rms. A normal-incidence reflectance of 50% at a wavelength of 13 nm was measured for a Mo/Si multilayer soft-x-ray mirror with 30 double layers (N = 30) deposited onto the BK7/C substrate, whereas a similar Mo/Si multilayer (N = 30) evaporated directly onto the bare BK7 surface turned out to show a reflectance of only 42%.

Are the Polyomaviruses BK and JC Associated with Opportunistic Infections, Graft-versus-Host Disease, or Worse Outcomes in Adult Patients Receiving Their First Allogeneic Stem Cell Transplantation with Low-Dose Alemtuzumab?

PubMed

Schneidewind, Laila; Neumann, Thomas; Knoll, Florian; Zimmermann, Kathrin; Smola, Sigrun; Schmidt, Christian Andreas; Krüger, William

2017-01-01

The association of polyomaviruses BK and JC with other opportunistic infections and graft-versus-host disease (GvHD) in allogeneic stem cell transplantation is controversially discussed. We conducted a retrospective study of 64 adult patients who received their first allogeneic stem cell transplantation between March 2010 and December 2014; the follow-up time was 2 years. Acute leukemia was the most frequent underlying disease (45.3%), and conditioning included myeloablative (67.2%) and nonmyeloablative protocols (32.8%). All patients received 10 mg of alemtuzumab on day -2 (20 mg in case of mismatch) as GvHD prophylaxis. Twenty-seven patients (41.5%) developed cytomegalovirus (CMV) reactivation. BKPyV-associated hemorrhagic cystitis was diagnosed in 10 patients (15.6%). Other opportunistic infections caused by viruses or protozoa occurred rarely (<10%). There was no association of BKPyV or JCPyV with CMV reactivation, Epstein-Barr virus reactivation, human herpes virus 6, or parvovirus B19 infection requiring treatment. There was a significant correlation of BKPyV-associated hemorrhagic cystitis with toxoplasmosis (p = 0.013). Additionally, there was a significant link of simultaneous BKPyV and JCPyV viruria with toxoplasmosis (p = 0.047). BKPyV and JCPyV were not associated with GvHD, relapse, or death. We found no association of BKPyV or JCPyV with viral infections or GvHD. Only the correlation of both polyomaviruses with toxoplasmosis was significant. This is a novel and interesting finding. © 2017 S. Karger AG, Basel.

Brain Korea 21 Phase II: A New Evaluation Model. Monograph

ERIC Educational Resources Information Center

Seong, Somi; Popper, Steven W.; Goldman, Charles A.; Evans, David K.

2008-01-01

In the late 1990s, the Korea Ministry of Education and Human Resources, in response to concern over the relatively low standing of the nation's universities and researchers, launched the Brain Korea 21 program BK21). BK21 seeks to make Korean research universities globally competitive and to produce more high-quality researchers in Korea. It…

Allocate carbon for a reason: priorities are reflected in the ¹³C/¹²C ratios of plant lipids synthesized via three independent biosynthetic pathways.

PubMed

Zhou, Youping; Stuart-Williams, Hilary; Grice, Kliti; Kayler, Zachary E; Zavadlav, Saša; Vogts, Angela; Rommerskirchen, Florian; Farquhar, Graham D; Gessler, Arthur

2015-03-01

It has long been theorized that carbon allocation, in addition to the carbon source and to kinetic isotopic effects associated with a particular lipid biosynthetic pathway, plays an important role in shaping the carbon isotopic composition ((13)C/(12)C) of lipids (Park and Epstein, 1961). If the latter two factors are properly constrained, valuable information about carbon allocation during lipid biosynthesis can be obtained from carbon isotope measurements. Published work of Chikaraishi et al. (2004) showed that leaf lipids isotopic shifts from bulk leaf tissue Δδ(13)C(bk-lp) (defined as δ(13)C(bulkleaftissue)-δ(13)C(lipid)) are pathway dependent: the acetogenic (ACT) pathway synthesizing fatty lipids has the largest isotopic shift, the mevalonic acid (MVA) pathway synthesizing sterols the lowest and the phytol synthesizing 1-deoxy-D-xylulose 5-phosphate (DXP) pathway gives intermediate values. The differences in Δδ(13)C(bk-lp) between C3 and C4 plants Δδ(13)C(bk-lp,C4-C3) are also pathway-dependent: Δδ(13)C(ACT)(bk-lp,C4-C3) > Δδ(13)C(DXP(bk-lp,C4-C3) > Δδ(13)C(MVA)(bk-lp,C4-C3). These pathway-dependent differences have been interpreted as resulting from kinetic isotopic effect differences of key but unspecified biochemical reactions involved in lipids biosynthesis between C3 and C4 plants. After quantitatively considering isotopic shifts caused by (dark) respiration, export-of-carbon (to sink tissues) and photorespiration, we propose that the pathway-specific differences Δδ(13)C(bk-lp,C4-C3) can be successfully explained by C4-C3 carbon allocation (flux) differences with greatest flux into the ACT pathway and lowest into the MVA pathways (when flux is higher, isotopic shift relative to source is smaller). Highest carbon allocation to the ACT pathway appears to be tied to the most stringent role of water-loss-minimization by leaf waxes (composed mainly of fatty lipids) while the lowest carbon allocation to the MVA pathway can be largely explained

Demonstration of extrapulmonary activity of angiotensin converting enzyme in intact tissue preparations.

PubMed Central

Lembeck, F.; Griesbacher, T.; Eckhardt, M.

1990-01-01

1. The activity of angiotensin converting enzyme (ACE) has been studied on functional parameters of intact isolated preparations of extrapulmonary tissues. The conversion of angiotensin I (A I) to angiotensin II (A II) and the cleavage of bradykinin (BK) were used as indicators of ACE activity. Captopril was employed as a specific inhibitor of ACE. 2. Captopril augmented the BK-induced contractions of the rat isolated uterus, the BK- and substance P-induced contractions of the guinea-pig ileum, and the BK-induced venoconstriction in the isolated perfused ear of the rabbit. Degradation of BK by ACE was calculated to be 52% in the rat uterus and 75% in the rabbit perfused ear. 3. Captopril inhibited the A I-induced contractions of the rat isolated colon, the A I-induced vasoconstriction in the isolated perfused ear of the rabbit and the rise in blood pressure induced by i.a. injections of A I in pithed rats. Conversion of A I to A II was calculated to be 13% in the rat colon and 26% in the rabbit perfused ear. 4. From estimations of the A II activity (bioassay on the rat colon) in the effluent of the perfused ear of the rabbit after injections of A I into the arterial inflow cannula it was calculated that approximately one tenth of A I was converted to A II during a single passage through the ear (less than 15 s).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2164861

Effects of fragmentation, supplementation and the addition of phase II compost to 2nd break compost on mushroom (Agaricus bisporus) yield.

PubMed

Royse, Daniel J

2010-01-01

Double-cropping offers growers an opportunity to increase production efficiency while reducing costs. We evaluated degree of fragmentation, supplementation, and addition of phase II compost (PIIC) to 2nd break compost (2BkC) on mushroom yield and biological efficiency (BE%). One crop was extended as a triple crop in which we evaluated effect of compost type, and addition of phase II compost and supplement. All crops involved removing the casing layer after 2nd break and then using 2BkC for the various treatments. Simple fragmentation of the compost increased mushroom yield by 30% compared to non-fragmented compost. Addition of a commercial supplement to fragmented compost increased mushroom yield by 53-56% over non-supplemented, fragmented 2BkC. Fragmented, supplemented 2BkC resulted in a 99% and 108% yield increase over the non-fragmented control depending on degree of fragmentation (3x, 1x, respectively). A 3rd crop of mushrooms was produced from 2BkC, but yields were about one-half that of the 1st and 2nd crops. Double-cropping (and even triple-cropping) offers growers an opportunity to increase bio-efficiency, reduce production costs, and increase profitability. The cost of producing Agaricus bisporus continues to rise due to increasing expenses including materials, energy, and labor. Optimizing production practices, through double- or triple-cropping, could help growers become more efficient and competitive, and ensure the availability of mushrooms for consumers.

R- and S-terbutaline activate large conductance and Ca2+ dependent K+ (BKCa) channel through interacting with β2 and M receptor respectively.

PubMed

Fan, Zhuo; Lin, Wei; Lv, Nanying; Ye, Yanrui; Tan, Wen

2016-11-01

This study investigated the effect of the β 2 receptor agonist terbutaline on the single channel activity of BK Ca channel. The effects of racemate and two isomers of terbutaline were all assessed. β 2 adrenoceptors were stably overexpressed on HEK293 cells by lentiviral transduction method and chicken BK Ca channels were transiently expressed on normal HEK293 cell line or HEK293 cells overexpressing β 2 receptors. Data showed that terbutaline significantly increased the single channel open probability of BK Ca channel within 10min. The channel activating effects of terbutaline are stereoselective and mainly stay with the R-enantiomers. The opening probability of BK Ca channel at 10min after drug application normalized to that just before drug application (Po10/Po0s) for R- and S-terbutaline were 7.85±3.20 and 1.06±0.45 respectively at 1μM concentration, corresponding to 28.37±9.96 and 2.68±1.09 at the higher concentration of 10μM. ICI 118551 blocked the effect of R- but not S-terbutaline (10μM), whereas atropine blocked the channel activating effects of S-terbutaline of higher concentration. In addition, the muscarinic receptor agonist carbachol increased the BK Ca channel activity in an atropine-sensitive manner as an positive control experiment, which indicate the involvement of M receptor in the channel activating effect of S-terbutaline. Copyright © 2016. Published by Elsevier B.V.

Effect of a kinin B2 receptor antagonist on LPS- and cytokine-induced neutrophil migration in rats

PubMed Central

Santos, Danielle R; Calixto, João B; Souza, Glória E P

2003-01-01

This study examines the involvement of kinins in neutrophil migration into rat subcutaneous air pouches triggered by lipopolysaccharide (LPS), as well as the putative roles played by kinin B1 and B2 receptors, tumour necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β) and selectins in this response. LPS (5 ng to 10 μg cavity−1) injected into the 6-day-old pouch induced a dose- and time-dependent neutrophil migration which peaked between 4 and 6 h, and was maximal following the dose of 100 ng cavity−1 (saline: 0.46±0.1; LPS: 43±3.70 × 106 cells cavity−1 at 6 h). Bradykinin (BK) (600 nmol) injected into the pouch of saline-treated rats induced only modest neutrophil migration (0.73±0.16 × 106 cells cavity−1). A more robust response to BK (3.2±0.25 × 106 cells cavity−1) was seen in animals pretreated with captopril, but this was still smaller than the responses to IL-1β or TNF-α (15 pmol: 23±2.2 × 106 and 75 pmol: 29.5±2 × 106 cells cavity−1, respectively). Nevertheless, the B1 agonist des-Arg9-BK (600 nmol) failed to induce neutrophil migration. HOE-140 (1 and 2 mg kg−1), a B2 receptor antagonist, reduced LPS-induced neutrophil migration. HOE-140 also reduced the neutrophil migration induced by BK, but had no effect on the migration promoted by IL-1β or TNF-α. des-Arg9-[Leu8]-BK, B1 receptor antagonist was ineffective in changing neutrophil migration caused by any of these stimuli. Neutrophil migration induced by LPS or BK was reduced by interleukin-1 receptor antagonist (IL-1ra) (1 mg kg−1), sheep anti-rat TNF serum (anti-TNF serum) (0.3 ml cavity−1), and the nonspecific selectin inhibitor fucoidin (10 mg kg−1). TNF-α levels in the pouch fluid were increased by LPS or BK injection, peaking at 0.5–1 h and gradually declining thereafter up to 6 h. IL-1β levels increased steadily throughout the 6 h period. HOE-140 markedly inhibited the rise in IL-1β and TNF-α levels in pouch fluid triggered by both stimuli. These

Off-the-Shelf Virus-Specific T Cells to Treat BK Virus, Human Herpesvirus 6, Cytomegalovirus, Epstein-Barr Virus, and Adenovirus Infections After Allogeneic Hematopoietic Stem-Cell Transplantation.

PubMed

Tzannou, Ifigeneia; Papadopoulou, Anastasia; Naik, Swati; Leung, Kathryn; Martinez, Caridad A; Ramos, Carlos A; Carrum, George; Sasa, Ghadir; Lulla, Premal; Watanabe, Ayumi; Kuvalekar, Manik; Gee, Adrian P; Wu, Meng-Fen; Liu, Hao; Grilley, Bambi J; Krance, Robert A; Gottschalk, Stephen; Brenner, Malcolm K; Rooney, Cliona M; Heslop, Helen E; Leen, Ann M; Omer, Bilal

2017-11-01

Purpose Improvement of cure rates for patients treated with allogeneic hematopoietic stem-cell transplantation (HSCT) will require efforts to decrease treatment-related mortality from severe viral infections. Adoptively transferred virus-specific T cells (VSTs) generated from eligible, third-party donors could provide broad antiviral protection to recipients of HSCT as an immediately available off-the-shelf product. Patient and Methods We generated a bank of VSTs that recognized five common viral pathogens: Epstein-Barr virus (EBV), adenovirus (AdV), cytomegalovirus (CMV), BK virus (BKV), and human herpesvirus 6 (HHV-6). The VSTs were administered to 38 patients with 45 infections in a phase II clinical trial. Results A single infusion produced a cumulative complete or partial response rate of 92% (95% CI, 78.1% to 98.3%) overall and the following rates by virus: 100% for BKV (n = 16), 94% for CMV (n = 17), 71% for AdV (n = 7), 100% for EBV (n = 2), and 67% for HHV-6 (n = 3). Clinical benefit was achieved in 31 patients treated for one infection and in seven patients treated for multiple coincident infections. Thirteen of 14 patients treated for BKV-associated hemorrhagic cystitis experienced complete resolution of gross hematuria by week 6. Infusions were safe, and only two occurrences of de novo graft-versus host disease (grade 1) were observed. VST tracking by epitope profiling revealed persistence of functional VSTs of third-party origin for up to 12 weeks. Conclusion The use of banked VSTs is a feasible, safe, and effective approach to treat severe and drug-refractory infections after HSCT, including infections from two viruses (BKV and HHV-6) that had never been targeted previously with an off-the-shelf product. Furthermore, the multispecificity of the VSTs ensures extensive antiviral coverage, which facilitates the treatment of patients with multiple infections.

Outcomes of Highly Active Antiretroviral Therapy in the Context of Universal Access to Healthcare: The U.S. Military HIV Natural History Study

DTIC Science & Technology

2010-05-27

1996-2002. HIV Med 2005, 6:198-205. 24. Ahuja SK, Kulkarni H, Catano G, Agan BK, Camargo JF, He W, O’Connell RJ, Marconi VC, Delmar J, Eron J, et al...individuals in San Francisco . J Gen Intern Med 2009, 24:14-20. 41. Weintrob AC, Fieberg AM, Agan BK, Ganesan A, Crum-Cianflone NF, Marconi VC, Roediger M

78 FR 52410 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-23

... Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters AGENCY: Federal Aviation Administration (FAA... Deutschland GmbH (ECD) Model BO-105A, BO-105C, BO-105S, BO- 105LS A-1, BO-105LS A-3, MBB-BK 117 A-1, MBB-BK... directive (AD): 2013-16-13 Eurocopter Deutschland GmbH (ECD): Amendment 39-17551; Docket No. FAA-2012-0887...

Low-Dose Ethanol Preconditioning Protects Against Oxygen-Glucose Deprivation/Reoxygenation-Induced Neuronal Injury By Activating Large Conductance, Ca2+-Activated K+ Channels In Vitro.

PubMed

Su, Fang; Guo, An-Chen; Li, Wei-Wei; Zhao, Yi-Long; Qu, Zheng-Yi; Wang, Yong-Jun; Wang, Qun; Zhu, Yu-Lan

2017-02-01

Increasing evidence suggests that low to moderate ethanol ingestion protects against the deleterious effects of subsequent ischemia/reperfusion; however, the underlying mechanism has not been elucidated. In the present study, we showed that expression of the neuronal large-conductance, Ca 2+ -activated K + channel (BK Ca ) α-subunit was upregulated in cultured neurons exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) compared with controls. Preconditioning with low-dose ethanol (10 mmol/L) increased cell survival rate in neurons subjected to OGD/R, attenuated the OGD/R-induced elevation of cytosolic Ca 2+ levels, and reduced the number of apoptotic neurons. Western blots revealed that ethanol preconditioning upregulated expression of the anti-apoptotic protein Bcl-2 and downregulated the pro-apoptotic protein Bax. The protective effect of ethanol preconditioning was antagonized by a BK Ca channel inhibitor, paxilline. Inside-out patches in primary neurons also demonstrated the direct activation of the BK Ca channel by 10 mmol/L ethanol. The above results indicated that low-dose ethanol preconditioning exerts its neuroprotective effects by attenuating the elevation of cytosolic Ca 2+ and preventing neuronal apoptosis, and this is mediated by BK Ca channel activation.

The control of microvascular permeability and blood pressure by neutral endopeptidase.

PubMed

Lu, B; Figini, M; Emanueli, C; Geppetti, P; Grady, E F; Gerard, N P; Ansell, J; Payan, D G; Gerard, C; Bunnett, N

1997-08-01

Plasma extravasation from postcapillary venules is one of the earliest steps of inflammation. Substance P (SP) and bradykinin (BK) mediate extravasation and cause hypotension. The cell-surface enzyme neutral endopeptidase (NEP) inactivates both peptides. Thus, absence of NEP may predispose development of inflammation and hypotension. We examined these possibilities in mice in which the NEP gene was deleted by homologous recombination. There was widespread basal plasma extravasation in postcapillary venular endothelia in NEP-/- mice, which was reversed by recombinant NEP and antagonists of SP (NK1) and BK (B2) receptors. Mean arterial blood pressure was 20% lower in NEP-/- animals, but this was unaffected by reintroduction of recombinant NEP and the kinin receptor antagonists. The hypotension was also independent of nitric oxide (NO), because NEP-/- mice treated with a NO synthase inhibitor remained hypotensive relative to the wild type. Thus, NEP has important roles in regulating basal microvascular permeability by degrading SP and BK, and may regulate blood pressure set point through a mechanism that is independent of SP, BK and NO. The use of NEP antagonists as candidate drugs in cardiovascular disease is suggested by the blood pressure data reported herein.

Vascular Reactivity Profile of Novel KCa3.1-Selective Positive-Gating Modulators in the Coronary Vascular Bed

PubMed Central

Oliván-Viguera, Aida; Valero, Marta Sofía; Pinilla, Estéfano; Amor, Sara; García-Villalón, Ángel Luis; Coleman, Nichole; Laría, Celia; Calvín-Tienza, Víctor; García-Otín, Ángel-Luis; Fernández-Fernández, José M.; Murillo, Ma Divina; Gálvez, José A.; Díaz-de-Villegas, María D.; Badorrey, Ramón; Simonsen, Ulf; Rivera, Luis; Wulff, Heike; Köhler, Ralf

2017-01-01

Opening of intermediate-conductance calcium-activated potassium channels (KCa3.1) produces membrane hyperpolarization in the vascular endothelium. Here, we studied the ability of two new KCa3.1-selective positive-gating modulators, SKA-111 and SKA-121, to (1) evoke porcine endothelial cell KCa3.1 membrane hyperpolarization, (2) induce endothelium-dependent and, particularly, endothelium-derived hyperpolarization (EDH)-type relaxation in porcine coronary arteries (PCA) and (3) influence coronary artery tone in isolated rat hearts. In whole-cell patch-clamp experiments on endothelial cells of PCA (PCAEC), KCa currents evoked by bradykinin (BK) were potentiated ≈7-fold by either SKA-111 or SKA-121 (both at 1 μM) and were blocked by a KCa3.1 blocker, TRAM-34. In membrane potential measurements, SKA-111 and SKA-121 augmented bradykinin-induced hyperpolarization. Isometric tension measurements in large- and small-calibre PCA showed that SKA-111 and SKA-121 potentiated endothelium-dependent relaxation with intact NO synthesis and EDH-type relaxation to BK by ≈2-fold. Potentiation of the BK response was prevented by KCa3.1 inhibition. In Langendorff-perfused rat hearts, SKA-111 potentiated coronary vasodilation elicited by BK. In conclusion, our data show that positive-gating modulation of KCa3.1 channels improves BK-induced membrane hyperpolarization and endothelium-dependent relaxation in small and large PCA as well as in the coronary circulation of rats. Positive-gating modulators of KCa3.1 could be therapeutically useful to improve coronary blood flow and counteract impaired coronary endothelial dysfunction in cardiovascular disease. PMID:26821335

Bradykinin mediates myogenic differentiation in murine myoblasts through the involvement of SK1/Spns2/S1P2 axis.

PubMed

Bruno, Gennaro; Cencetti, Francesca; Bernacchioni, Caterina; Donati, Chiara; Blankenbach, Kira Vanessa; Thomas, Dominique; Meyer Zu Heringdorf, Dagmar; Bruni, Paola

2018-05-01

Skeletal muscle tissue retains a remarkable regenerative capacity due to the activation of resident stem cells that in pathological conditions or after tissue damage proliferate and commit themselves into myoblasts. These immature myogenic cells undergo differentiation to generate new myofibers or repair the injured ones, giving a strong contribution to muscle regeneration. Cytokines and growth factors, potently released after tissue injury by leukocytes and macrophages, are not only responsible of the induction of the initial inflammatory response, but can also affect skeletal muscle regeneration. Growth factors exploit sphingosine kinase (SK), the enzyme that catalyzes the production of sphingosine 1-phosphate (S1P), to exert their biological effects in skeletal muscle. In this paper we show for the first time that bradykinin (BK), the leading member of kinin/kallikrein system, is able to induce myogenic differentiation in C2C12 myoblasts. Moreover, evidence is provided that SK1, the specific S1P-transporter spinster homolog 2 (Spns2) and S1P 2 receptor are involved in the action exerted by BK, since pharmacological inhibition/antagonism or specific down-regulation significantly alter BK-induced myogenic differentiation. Moreover, the molecular mechanism initiated by BK involves a rapid translocation of SK1 to plasma membrane, analyzed by time-lapse immunofluorescence analysis. The present study highlights the role of SK1/Spns2/S1P receptor 2 signaling axis in BK-induced myogenic differentiation, thus confirming the crucial involvement of this pathway in skeletal muscle cell biology. Copyright © 2018 Elsevier Inc. All rights reserved.

Spontaneously released substance P and bradykinin from isolated guinea-pig bladder.

PubMed

Saban, R; Franz, J; Bjorling, D E

1997-04-01

To investigate whether the isolated urinary bladder spontaneously releases substance P (SP) or bradykinin (BK), which can act as potent mediators of pain and inflammation of the urinary bladder, and whether peptidase inhibitors enhance peptide release. Urinary bladder segments (2 x 10 x 0.8-1 mm) were isolated from guinea pigs and studied in vitro; tissue contraction was assessed using force-displacement transducers and the release of peptides by specific enzyme immunoassays. In the absence of any exogenous agonists, the inhibition of neutral endopeptidase and angiotensin-converting enzyme by phosphoramidon and captopril, respectively, increased the frequency and magnitude of spontaneous motility of isolated bladder strips. Phosphoramidon increased the net release of SP-like immunoreactivity (SP-LI) and captopril increased the net release of SP-LI and BK-LI, concomitant with contraction. Peptide-LI was recovered primarily from bladder mucosa and to a lesser degree from detrusor smooth muscle. Similarly, peptidase inhibitors primarily affected the bladder mucosa; phosphoramidon induced a fourfold increase in SP-LI and captopril induced a significant increase of SP-LI and BK-LI from the mucosa. Tissues contracted in response to peptidase inhibitors in the presence of atropine and indomethacin, but contraction was reduced significantly by in vitro capsaicin desensitization or removal of bladder mucosa. BK stimulated SP-LI release from mucosa but not detrusor. SP stimulated increased BK-LI release from mucosa and detrusor. These findings indicate the basal release of peptide-like immunoreactivity by isolated bladder and further support the concept that peptidases located in the bladder mucosa are important in terminating the effects of endogenous peptides.

Non-Destructive Measurement Methods (Neutron-, X-ray Radiography, Vibration Diagnostics and Ultrasound) in the Inspection of Helicopter Rotor Blades

DTIC Science & Technology

2005-04-01

the radiography gauging. In addition to the Statistical Energy Analysis (SEA) measurement a small exciter table (BK4810) and impedance head (BK 8000... Statistical Energy Analysis ; 7th Conf. on Vehicle System Dynamics, Identification and Anomalies (VSDIA2000), 6-8 Nov. 2000 Budapest, Proc. pp. 491-493... Energy Analysis (SEA) and Ultrasound Test. (UT) were concurrently applied. These methods collect accessory information on the objects under inspection

Retinal plasma extravasation in streptozotocin-diabetic rats mediated by kinin B1 and B2 receptors

PubMed Central

Abdouh, M; Talbot, S; Couture, R; Hasséssian, H M

2008-01-01

Background and purpose: We investigated whether or not kinin receptors play a role in diabetic blood–retinal barrier breakdown, which is a leading cause of vision loss. Experimental approach: Blood–retinal barrier breakdown was quantified using Evans blue, and expression of kinin B1 receptor mRNA was measured using quantitative reverse transcrition-PCR. Diabetic rats (streptozotocin (STZ), 65 mg kg−1) received a single intraocular injection of bradykinin (BK) or des-Arg9-BK, alone, or in combination with antagonists for B1 (des-Arg10-Hoe140, R-715) and/or B2 (Hoe140) receptors, given intraocularly or intravenously (i.v.). Key results: In control rats, BK (0.1–10 nmol) dose-dependently increased plasma extravasation, which was inhibited by Hoe140 (0.2 nmol), whereas des-Arg9-BK (0.1 and 1 nmol) was without effect. B1 receptor mRNA was markedly increased in retinas of diabetic rats, and this was prevented by N-acetyl-L-cysteine (1 g kg−1 day−1 for 7 days). Plasma extravasation in retinas of STZ-diabetic rats was higher than in controls and enhanced by des-Arg9-BK. Response to des-Arg9-BK was inhibited by intraocular or i.v. injection of B1 receptor antagonists. Diabetes-induced plasma extravasation was inhibited only by a combination of des-Arg10-Hoe140 and Hoe 140 (100 nmol kg−1, i.v. 15 min earlier) or by R-715 (1 μmol kg−1, i.v.) injected daily for 7 days. Conclusions and implications: Kinin B1 receptors are upregulated in retinas of STZ-diabetic rats through a mechanism involving oxidative stress. Both kinin B1 and B2 receptors contribute to increased plasma extravasation in diabetic retinopathy. Chronic inhibition of both kinin receptors, possibly with antioxidant adjuvants, may be a novel therapeutic strategy for diabetic retinopathy. PMID:18311190

Comparison of Radiofrequency-targeted Vertebral Augmentation With Balloon Kyphoplasty for the Treatment of Vertebral Compression Fractures: 2-Year Results.

PubMed

Bornemann, Rahel; Jansen, Tom R; Kabir, Koroush; Pennekamp, Peter H; Stüwe, Brit; Wirtz, Dieter C; Pflugmacher, Robert

2017-04-01

A retrospective study. The aim of this study was the evaluation of the safety and effectiveness of radiofrequency-targeted vertebral augmentation (RF-TVA) in comparison with balloon kyphoplasty (BK) for the treatment of acute painful vertebral compression fractures (VCFs) on the basis of matched pairs. Vertebroplasty and BK are the common surgical interventions for the treatment of VCF. Both are effective and safe but pose some risks such as adjacent fractures and cement leakage. In 2009, RF-TVA was introduced as an innovative augmentation procedure for the treatment of VCF. A total of 192 patients (116 female; 51-90 y) with VCF (n=303) at 1 to 3 levels were treated with RF-TVA or BK. Functionality (Oswestry Disability Index), pain (visual analogue scale), vertebral height (anterior, middle), and kyphotic angle were evaluated over a 2-year period (postoperatively, 3-4 d, 3, 6, 12, and 24 mo). In addition, operating time and occurrence of cement leakage were recorded. Pain and functionality were significantly improved after both treatments. In both groups, there was an increase in the vertebral height and a decrease in the kyphotic angle, which remained relatively consistent during 24 months. The incidence of cement leakage was 9.4% (n=9) in the RF-TVA group and 24.0% (n=25) in the BK group. The mean operating time with radiofrequency kyphoplasty was 25.9±9.9 minutes, and with balloon kyphoplasty 48.0±18.4 minutes. RF-TVA is a safe and effective procedure for the treatment of vertebral compression fractures when compared with BK. Improvement in pain and functional scores after RF-TVA are durable through 24 months postprocedure and remained better than those after BK at long-term follow-up. Operating time for RF-TVA is shorter and the risk of cement leakage is lower. Both procedures provided similar results in vertebral height restoration and reduction in the kyphotic angle.

KAST Study: The Kiva System As a Vertebral Augmentation Treatment-A Safety and Effectiveness Trial: A Randomized, Noninferiority Trial Comparing the Kiva System With Balloon Kyphoplasty in Treatment of Osteoporotic Vertebral Compression Fractures.

PubMed

Tutton, Sean M; Pflugmacher, Robert; Davidian, Mark; Beall, Douglas P; Facchini, Francis R; Garfin, Steven R

2015-06-15

The KAST (Kiva Safety and Effectiveness Trial) study was a pivotal, multicenter, randomized control trial for evaluation of safety and effectiveness in the treatment of patients with painful, osteoporotic vertebral compression fractures (VCFs). The objective was to demonstrate noninferiority of the Kiva system to balloon kyphoplasty (BK) with respect to the composite primary endpoint. Annual incidence of osteoporotic VCFs is prevalent. Optimal treatment of VCFs should address pain, function, and deformity. Kiva is a novel implant for vertebral augmentation in the treatment of VCFs. A total of 300 subjects with 1 or 2 painful osteoporotic VCFs were randomized to blindly receive Kiva (n = 153) or BK (n = 147). Subjects were followed through 12 months. The primary endpoint was a composite at 12 months defined as a reduction in fracture pain by at least 15 mm on the visual analogue scale, maintenance or improvement in function on the Oswestry Disability Index, and absence of device-related serious adverse events. Secondary endpoints included cement usage, extravasation, and adjacent level fracture. A mean improvement of 70.8 and 71.8 points in the visual analogue scale score and 38.1 and 42.2 points in the Oswestry Disability Index was noted in Kiva and BK, respectively. No device-related serious adverse events occurred. Despite significant differences in risk factors favoring the control group at baseline, the primary endpoint demonstrated noninferiority of Kiva to BK. Analysis of secondary endpoints revealed superiority with respect to cement use and site-reported extravasation and a positive trend in adjacent level fracture warranting further study. The KAST study successfully established that the Kiva system is noninferior to BK based on a composite primary endpoint assessment incorporating pain-, function-, and device-related serious adverse events for the treatment of VCFs due to osteoporosis. Kiva was shown to be noninferior to BK and revealed a positive trend

Differential efficacy of GoSlo-SR compounds on BKα and BKαγ1–4 channels

PubMed Central

Kshatri, Aravind S.; Li, Qin; Yan, Jiusheng; Large, Roddy J.; Sergeant, Gerard P.; McHale, Noel G.; Thornbury, Keith D.; Hollywood, Mark A.

2017-01-01

ABSTRACT Large conductance, voltage and Ca2+ activated K+ channels (BK channels) are abundantly expressed throughout the body and are important regulators of smooth muscle tone and neuronal excitability. Their dysfunction is implicated in various diseases including overactive bladder, hypertension and erectile dysfunction. Therefore, BK channel openers bear significant therapeutic potential to treat the above diseases. GoSlo-SR compounds were designed to be potent and efficacious BK channel openers. Although their structural activity relationships, activation in both BKα and BKαβ channels and the hypothetical mode of action of these compounds has been studied in detail in recent years, their effectiveness to open the BKαγ channels still remains unexplored. In this study, we have examined the efficacy of 3 closely related GoSlo-SR openers, GoSlo-SR-5-6 (SR-5-6), GoSlo-SR-5-44 (SR-5-44) and GoSlo-SR-5-130 (SR-5-130) using inside out patches on BKα channels coexpressed with 4 different LRRC (γ1–4) subunits in HEK293 cells. Our data suggests that the activation effects due to SR-5-6 were not significantly affected in the presence of γ1–4 subunits. Interestingly, the effects of more efficacious BK channel opener SR-5-44 were altered by different γ subunits. In cells expressing BKα channels, the shift in V1/2 (ΔV1/2) induced by SR-5-44 (3 μM) was −76 ± 3 mV, whereas it was significantly reduced by ∼70 % in BKαγ1 channels (ΔV1/2= −23 ± 3, p < 0.001, ANOVA). In BKαγ2 channels the ΔV1/2 was −36 ± 1 mV, which was less than that observed in BKαγ3 and BKαγ4 channels where the ΔV1/2 was −47 ± 5 mV, and −82 ± 5 mV, respectively. Additionally, the excitatory effects of a ‘β specific’ BK channel opener, SR-5-130 were only partially restored in the patches containing BKαγ1–4 channels. Together this data highlights that subtle modifications in GoSlo-SR structures alter their effectiveness on BK channels with accessory �

NLO evolution of color dipole

DOE PAGES

Balitsky, Ian; Chirilli, Giovanni A.

2008-09-01

The small-x deep inelastic scattering in the saturation region is governed by the non-linear evolution of Wilson-line operators. In the leading logarithmic approximation it is given by the BK equation for the evolution of color dipoles. In the next-to-leading order the BK equation gets contributions from quark and gluon loops as well as from the tree gluon diagrams with quadratic and cubic nonlinearities.

Vascular Reactivity Profile of Novel KCa 3.1-Selective Positive-Gating Modulators in the Coronary Vascular Bed.

PubMed

Oliván-Viguera, Aida; Valero, Marta Sofía; Pinilla, Estéfano; Amor, Sara; García-Villalón, Ángel Luis; Coleman, Nichole; Laría, Celia; Calvín-Tienza, Víctor; García-Otín, Ángel-Luis; Fernández-Fernández, José M; Murillo, M Divina; Gálvez, José A; Díaz-de-Villegas, María D; Badorrey, Ramón; Simonsen, Ulf; Rivera, Luis; Wulff, Heike; Köhler, Ralf

2016-08-01

Opening of intermediate-conductance calcium-activated potassium channels (KC a 3.1) produces membrane hyperpolarization in the vascular endothelium. Here, we studied the ability of two new KC a 3.1-selective positive-gating modulators, SKA-111 and SKA-121, to (1) evoke porcine endothelial cell KC a 3.1 membrane hyperpolarization, (2) induce endothelium-dependent and, particularly, endothelium-derived hyperpolarization (EDH)-type relaxation in porcine coronary arteries (PCA) and (3) influence coronary artery tone in isolated rat hearts. In whole-cell patch-clamp experiments on endothelial cells of PCA (PCAEC), KC a currents evoked by bradykinin (BK) were potentiated ≈7-fold by either SKA-111 or SKA-121 (both at 1 μM) and were blocked by a KC a 3.1 blocker, TRAM-34. In membrane potential measurements, SKA-111 and SKA-121 augmented bradykinin-induced hyperpolarization. Isometric tension measurements in large- and small-calibre PCA showed that SKA-111 and SKA-121 potentiated endothelium-dependent relaxation with intact NO synthesis and EDH-type relaxation to BK by ≈2-fold. Potentiation of the BK response was prevented by KC a 3.1 inhibition. In Langendorff-perfused rat hearts, SKA-111 potentiated coronary vasodilation elicited by BK. In conclusion, our data show that positive-gating modulation of KC a 3.1 channels improves BK-induced membrane hyperpolarization and endothelium-dependent relaxation in small and large PCA as well as in the coronary circulation of rats. Positive-gating modulators of KC a 3.1 could be therapeutically useful to improve coronary blood flow and counteract impaired coronary endothelial dysfunction in cardiovascular disease. © 2016 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

Contribution of B2 receptors for bradykinin in Arthus reaction-induced plasma extravasation in wild-type or B2 transgenic knockout mice

PubMed Central

Samadfam, R; Teixeira, C; Bkaily, G; Sirois, P; de Brum-Fernandes, A; D'Orleans-Juste, P

2000-01-01

The aim of the present study was to investigate the contribution of bradykinin (BK) B1 and B2 receptors in a model of type III hypersensitivity, the reverse passive Arthus reaction (RPA), in wild-type mice and transgenic B2 knockout littermates.BK (10 μg mouse−1) or bovine serum albumin (0.5 mg mouse−1) induced a sustained Evans blue extravasation for more than 80 min in naive or rabbit anti-bovine serum albumin-treated mice (RPA model), respectively. The response to the two stimuli was prevented by the B2 receptor antagonist, HOE-140, but not by [Leu8]desArg9-BK (B1 receptor antagonist).In contrast to the wild-type littermates, RPA and bradykinin were unable to trigger an increase in plasma extravasation in B2 knockout mice.Furthermore, endothelin-1 (5 μg mouse−1) and a selective NK-1 receptor agonist [Sar9,Met (O2)11]-SP (20 μg mouse−1), triggered a significant increase in peritoneal plasma extravasation in both wild-type and B2 knockout animals.A pretreatment with indomethacin (200 μg mouse−1) significantly reduced the RPA-induced but not the BK-induced increase in Evans blue extravasation. Furthermore, RPA, but not BK, triggered a significant indomethacin-sensitive increase in peritoneal prostaglandin E2 content.Our results suggest a pivotal role for B2 receptors in the mechanism of plasma extravasation which occurs during the reverse passive Arthus reaction in the mouse. Moreover, our results suggest an important contribution of prostanoids in the plasma leakage mechanisms triggered by RPA but not by bradykinin. PMID:10780980

Increase in cortical pyramidal cell excitability accompanies depression-like behavior in mice: a transcranial magnetic stimulation study.

PubMed

Sun, Peng; Wang, Furong; Wang, Li; Zhang, Yu; Yamamoto, Ryo; Sugai, Tokio; Zhang, Qing; Wang, Zhengda; Kato, Nobuo

2011-11-09

Clinical evidence suggests that cortical excitability is increased in depressives. We investigated its cellular basis in a mouse model of depression. In a modified version of forced swimming (FS), mice were initially forced to swim for 5 consecutive days and then were treated daily with repetitive transcranial magnetic stimulation (rTMS) or sham treatment for the following 4 weeks without swimming. On day 2 through day 5, the mice manifested depression-like behaviors. The next and last FS was performed 4 weeks later, which revealed a 4 week maintenance of depression-like behavior in the sham mice. In slices from the sham controls, excitability in cingulate cortex pyramidal cells was elevated in terms of membrane potential and frequencies of spikes evoked by current injection. Depolarized resting potential was shown to depend on suppression of large conductance calcium-activated potassium (BK) channels. This BK channel suppression was confirmed by measuring spike width, which depends on BK channels. Chronic rTMS treatment during the 4 week period significantly reduced the depression-like behavior. In slices obtained from the rTMS mice, normal excitability and BK channel activity were recovered. Expression of a scaffold protein Homer1a was reduced by the FS and reversed by rTMS in the cingulate cortex. Similar recovery in the same behavioral, electrophysiological, and biochemical features was observed after chronic imipramine treatment. The present study demonstrated that manifestation and disappearance of depression-like behavior are in parallel with increase and decrease in cortical neuronal excitability in mice and suggested that regulation of BK channels by Homer1a is involved in this parallelism.

Reduction by enhanced coagulation of dissolved organic nitrogen as a precursor of N-nitrosodimethylamine.

PubMed

Tongchang, Phanawan; Kumsuvan, Jindalak; Phatthalung, Warangkana Na; Suksaroj, Chaisri; Wongrueng, Aunnop; Musikavong, Charongpun

2018-05-12

Raw water from the Banglen (BL) water treatment plant (WTP) and Bangkhen (BK) WTP in central Thailand and Hatyai (HY) WTP in southern Thailand was investigated for dissolved organic nitrogen (DON) reduction. The DON(mg N/L) and the dissolved organic carbon (DOC)/DON ratio were 0.34 and 21, 0.24 and 18, and 1.12 and 3 for the raw waters from BL, BK, and HY WTPs, respectively. Polyaluminum chloride (PACl) dosages of 150, 80, and 40 mg/L at pH 7 were the optimal coagulation conditions for the raw waters from BL, BK, and HY WTPs, respectively, and could reduce DON by 50%, 42%, and 42%, respectively. PACl and powder activated carbon (PAC, both in mg/L) at 150 and 20, 80 and 20, and 40 and 60 could reduce DON in the raw waters from BL, BK, and HY WTPs by 71%, 67%, and 29%, respectively. DOC/DON values of water treated with PACl were similar to those of raw water. DOC/DON values of water treated with PACl and PAC were lower than those of raw water. N-nitrosodimethylamine (NDMA) formation potentials of raw water, water treated with PACl, or both PACl and PAC, and organic fractions of BL, BK, and HY WTPs were below the detection limits of 542 and 237 ng/L, respectively. Reductions in fluorescence intensities of tryptophan-like substances at peaks 240/350 and 280/350 (nm Ex /nm Em ) were moderately (correlation coefficient, R = 0.85 and 0.86) and fairly (R = 0.59, 0.67, and 0.75) correlated with DON reduction.

Chronic nitric oxide synthase inhibition blunts endothelium-dependent function of conduit coronary arteries, not arterioles

PubMed Central

Ingram, David G.; Newcomer, Sean C.; Price, Elmer M.; Eklund, Kevin E.; McAllister, Richard M.; Laughlin, M. Harold

2009-01-01

Current literature suggests that chronic nitric oxide synthase (NOS) inhibition has differential effects on endothelium-dependent dilation (EDD) of conduit arteries vs. arterioles. Therefore, we hypothesized that chronic inhibition of NOS would impair EDD of porcine left anterior descending (LAD) coronary arteries but not coronary arterioles. Thirty-nine female Yucatan miniature swine were included in the study. Animals drank either tap water or water with NG-nitro-L-arginine methyl ester (L-NAME; 100 mg/l), resulting in control and chronic NOS inhibition (CNI) groups, respectively. Treatment was continued for 1–3 mo (8.3 ± 0.6 mg · kg−1 · day−1). In vitro EDD of coronary LADs and arterioles was assessed via responses to ADP (LADs only) and bradykinin (BK), and endothelium-independent function was assessed via responses to sodium nitroprusside (SNP). Chronic NOS inhibition diminished coronary artery EDD to ADP and BK. Incubating LAD rings with L-NAME decreased relaxation responses of LADs from control pigs but not from CNI pigs such that between-group differences were abolished. Neither indomethacin (Indo) nor sulfaphenazole incubation significantly affected relaxation responses of LAD rings to ADP or BK. Coronary arteries from CNI pigs showed enhanced relaxation responses to SNP. In contrast to coronary arteries, coronary arterioles from CNI pigs demonstrated preserved EDD to BK and no increase in dilation responses to SNP. L-NAME, Indo, and L-NAME + Indo incubation did not result in significant between-group differences in arteriole dilation responses to BK. These results suggest that although chronic NOS inhibition diminishes EDD of LAD rings, most likely via a NOS-dependent mechanism, it does not affect EDD of coronary arterioles. PMID:17259441

The non-diuretic hypotensive effects of thiazides are enhanced during volume depletion states

PubMed Central

Alshahrani, Saeed; Rapoport, Robert M.; Zahedi, Kamyar; Jiang, Min; Nieman, Michelle; Barone, Sharon; Meredith, Andrea L.; Lorenz, John N.; Rubinstein, Jack

2017-01-01

Thiazide derivatives including Hydrochlorothiazide (HCTZ) represent the most common treatment of mild to moderate hypertension. Thiazides initially enhance diuresis via inhibition of the kidney Na+-Cl- Cotransporter (NCC). However, chronic volume depletion and diuresis are minimal while lowered blood pressure (BP) is maintained on thiazides. Thus, a vasodilator action of thiazides is proposed, likely via Ca2+-activated K+ (BK) channels in vascular smooth muscles. This study ascertains the role of volume depletion induced by salt restriction or salt wasting in NCC KO mice on the non-diuretic hypotensive action of HCTZ. HCTZ (20mg/kg s.c.) lowered BP in 1) NCC KO on a salt restricted diet but not with normal diet; 2) in volume depleted but not in volume resuscitated pendrin/NCC dKO mice; the BP reduction occurs without any enhancement in salt excretion or reduction in cardiac output. HCTZ still lowered BP following treatment of NCC KO on salt restricted diet with paxilline (8 mg/kg, i.p.), a BK channel blocker, and in BK KO and BK/NCC dKO mice on salt restricted diet. In aortic rings from NCC KO mice on normal and low salt diet, HCTZ did not alter and minimally decreased maximal phenylephrine contraction, respectively, while contractile sensitivity remained unchanged. These results demonstrate 1) the non-diuretic hypotensive effects of thiazides are augmented with volume depletion and 2) that the BP reduction is likely the result of HCTZ inhibition of vasoconstriction through a pathway dependent on factors present in vivo, is unrelated to BK channel activation, and involves processes associated with intravascular volume depletion. PMID:28719636

Determination of real-time polymerase chain reaction uncertainty of measurement using replicate analysis and a graphical user interface with Fieller’s theorem

PubMed Central

Stuart, James Ian; Delport, Johan; Lannigan, Robert; Zahariadis, George

2014-01-01

BACKGROUND: Disease monitoring of viruses using real-time polymerase chain reaction (PCR) requires knowledge of the precision of the test to determine what constitutes a significant change. Calculation of quantitative PCR confidence limits requires bivariate statistical methods. OBJECTIVE: To develop a simple-to-use graphical user interface to determine the uncertainty of measurement (UOM) of BK virus, cytomegalovirus (CMV) and Epstein-Barr virus (EBV) real-time PCR assays. METHODS: Thirty positive clinical samples for each of the three viral assays were repeated once. A graphical user interface was developed using a spreadsheet (Excel, Microsoft Corporation, USA) to enable data entry and calculation of the UOM (according to Fieller’s theorem) and PCR efficiency. RESULTS: The confidence limits for the BK virus, CMV and EBV tests were ∼0.5 log, 0.5 log to 1.0 log, and 0.5 log to 1.0 log, respectively. The efficiencies of these assays, in the same order were 105%, 119% and 90%. The confidence limits remained stable over the linear range of all three tests. DISCUSSION: A >5 fold (0.7 log) and a >3-fold (0.5 log) change in viral load were significant for CMV and EBV when the results were ≤1000 copies/mL and >1000 copies/mL, respectively. A >3-fold (0.5 log) change in viral load was significant for BK virus over its entire linear range. PCR efficiency was ideal for BK virus and EBV but not CMV. Standardized international reference materials and shared reporting of UOM among laboratories are required for the development of treatment guidelines for BK virus, CMV and EBV in the context of changes in viral load. PMID:25285125

Determination of real-time polymerase chain reaction uncertainty of measurement using replicate analysis and a graphical user interface with Fieller's theorem.

PubMed

Stuart, James Ian; Delport, Johan; Lannigan, Robert; Zahariadis, George

2014-07-01

Disease monitoring of viruses using real-time polymerase chain reaction (PCR) requires knowledge of the precision of the test to determine what constitutes a significant change. Calculation of quantitative PCR confidence limits requires bivariate statistical methods. To develop a simple-to-use graphical user interface to determine the uncertainty of measurement (UOM) of BK virus, cytomegalovirus (CMV) and Epstein-Barr virus (EBV) real-time PCR assays. Thirty positive clinical samples for each of the three viral assays were repeated once. A graphical user interface was developed using a spreadsheet (Excel, Microsoft Corporation, USA) to enable data entry and calculation of the UOM (according to Fieller's theorem) and PCR efficiency. The confidence limits for the BK virus, CMV and EBV tests were ∼0.5 log, 0.5 log to 1.0 log, and 0.5 log to 1.0 log, respectively. The efficiencies of these assays, in the same order were 105%, 119% and 90%. The confidence limits remained stable over the linear range of all three tests. A >5 fold (0.7 log) and a >3-fold (0.5 log) change in viral load were significant for CMV and EBV when the results were ≤1000 copies/mL and >1000 copies/mL, respectively. A >3-fold (0.5 log) change in viral load was significant for BK virus over its entire linear range. PCR efficiency was ideal for BK virus and EBV but not CMV. Standardized international reference materials and shared reporting of UOM among laboratories are required for the development of treatment guidelines for BK virus, CMV and EBV in the context of changes in viral load.

Hypersensitive prostaglandin and thromboxane response to hormones in rabbit colitis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zipser, R.D.; Patterson, J.B.; Kao, H.W.

1985-10-01

Inflammation of the colon is associated with increased production of prostaglandins (PG) and thromboxanes (Tx), and these eicosanoids may contribute to the inflammatory, secretory, and motility dysfunctions in colitis. To evaluate the potential role of peptide hormones in the enhanced eicosanoid release, colitis was established in rabbits by a delayed-type hypersensitivity reaction to dinitrochlorobenzene and by an immune-complex-mediated reaction. PG and Tx were identified in the venous effluent of isolated perfused colons by radiochromatography after ( UC)arachidonic acid prelabeling, as well as by bioassay, and then quantitated by immunoassay. The two colitis models were morphologically similar. Basal release of PGE2,more » PGI2, and TxA2 was two- to threefold greater from colitis tissue than from control tissue. Bradykinin (BK) and angiotensin II (ANG II) increased release of UC-labeled eicosanoids, whereas several gastrointestinal hormones had no effect. In control colons, BK and ANG II increased PGE2 and PGI2 release (by about 2-fold) but did not alter TxA2. In contrast, BK and ANG II markedly exaggerated the release of eicosanoids in colitis. Since BK and possibly ANG II are increased at sites of inflammation, the hypersensitive eicosanoid response to these peptides may augment the eicosanoid-mediated manifestations of colitis.« less

Which is best for osteoporotic vertebral compression fractures: balloon kyphoplasty, percutaneous vertebroplasty or non-surgical treatment? A study protocol for a Bayesian network meta-analysis

PubMed Central

Kan, Shun-Li; Yuan, Zhi-Fang; Chen, Ling-Xiao; Sun, Jing-Cheng; Ning, Guang-Zhi; Feng, Shi-Qing

2017-01-01

Introduction Osteoporotic vertebral compression fractures (OVCFs) commonly cause both acute and chronic back pain, substantial spinal deformity, functional disability and decreased quality of life and increase the risk of future vertebral fractures and mortality. Percutaneous vertebroplasty (PVP), balloon kyphoplasty (BK) and non-surgical treatment (NST) are mostly used for the treatment of OVCFs. However, which treatment is preferred is unknown. The purpose of this study is to comprehensively review the literature and ascertain the relative efficacy and safety of BK, PVP and NST for patients with OVCFs using a Bayesian network meta-analysis. Methods and analysis We will comprehensively search PubMed, EMBASE and the Cochrane Central Register of Controlled Trials, to include randomided controlled trials that compare BK, PVP or NST for treating OVCFs. The risk of bias for individual studies will be assessed according to the Cochrane Handbook. Bayesian network meta-analysis will be performed to compare the efficacy and safety of BK, PVP and NST. The quality of evidence will be evaluated by GRADE. Ethics and dissemination Ethical approval and patient consent are not required since this study is a meta-analysis based on published studies. The results of this network meta-analysis will be submitted to a peer-reviewed journal for publication. PROSPERO registration number CRD42016039452; Pre-results. PMID:28093431

Chemistry of berkelium: A review

NASA Astrophysics Data System (ADS)

Hobart, D. E.; Peterson, J. R.

Element 97 was first produced in December 1949, by the bombardment of americium-241 with accelerated alpha particles. This new element was named berkelium (Bk) after Berkeley, California, the city of its discovery. In the 36 years since the discovery of Bk, a substantial amount of knowledge concerning the physicochemical properties of this relatively scarce transplutonium element was acquired. All of the Bk isotopes of mass numbers 240 and 242 through 251 are presently known, but only berkelium-249 is available in sufficient quantities for bulk chemical studies. About 0.7 gram of this isotope was isolated at the HFIR/TRU Complex in Oak Ridge, Tennessee in the last 18 years. Over the same time period, the scale of experimental work using berkelium-249 has increased from the tracer level to bulk studies at the microgram level to solution and solid state investigations with milligram quantities. Extended knowledge of the physicochemical behavior of berkelium is important in its own right, because Bk is the first member of the second half of the actinide series. In addition, such information should enable more accurate extrapolations to the predicted behavior of heavier elements for which experimental studies are severely limited by lack of material and/or by intense radioactivity.

Replica exchange with solute tempering: A method for sampling biological systems in explicit water

NASA Astrophysics Data System (ADS)

Liu, Pu; Kim, Byungchan; Friesner, Richard A.; Berne, B. J.

2005-09-01

An innovative replica exchange (parallel tempering) method called replica exchange with solute tempering (REST) for the efficient sampling of aqueous protein solutions is presented here. The method bypasses the poor scaling with system size of standard replica exchange and thus reduces the number of replicas (parallel processes) that must be used. This reduction is accomplished by deforming the Hamiltonian function for each replica in such a way that the acceptance probability for the exchange of replica configurations does not depend on the number of explicit water molecules in the system. For proof of concept, REST is compared with standard replica exchange for an alanine dipeptide molecule in water. The comparisons confirm that REST greatly reduces the number of CPUs required by regular replica exchange and increases the sampling efficiency. This method reduces the CPU time required for calculating thermodynamic averages and for the ab initio folding of proteins in explicit water. Author contributions: B.J.B. designed research; P.L. and B.K. performed research; P.L. and B.K. analyzed data; and P.L., B.K., R.A.F., and B.J.B. wrote the paper.Abbreviations: REST, replica exchange with solute tempering; REM, replica exchange method; MD, molecular dynamics.*P.L. and B.K. contributed equally to this work.

Breakdown evaluation of corneal epithelial barrier caused by antiallergic eyedrops using an electrophysiologic method.

PubMed

Nakashima, Mikiro; Nakamura, Tadahiro; Teshima, Mugen; To, Hideto; Uematsu, Masafumi; Kitaoka, Takashi; Taniyama, Kotaro; Nishida, Koyo; Nakamura, Junzo; Sasaki, Hitoshi

2008-02-01

The aim of this study was to examine the usefulness of an electrophysiologic method for predicting corneal epithelial breakdown by antiallergic eyedrops and comparing the results with those in other appraisal methods. Six kinds of antiallergic eyedrops, including benzalkonium chloride (BK) as an ophthalmic preservative and two kinds of BK-free antiallergic eyedrops, were used in this study. Eyedrops were applied to excise rabbit corneas and monitoring was performed according to an electrophysiologic method, using a commercially available chamber system to mimic human tear turnover. Changes in transepithelial electrical resistance (TEER) in the corneal surface were recorded. The cytotoxicity of each kind of eyedrops in a normal rabbit corneal epithelial (NRCE) cell line and a human endothelial cell line EA.hy926 was also examined. The extent of decrease in the corneal TEER after applying antiallergic eyedrops was dependent on the concentration of the BK included as a preservative, but it was also affected by the different kinds of drugs when the BK concentration was low. Higher cytotoxicity of the eyedrops against the NRCE and EA.hy926 cell lines was observed with a reduction of TEER. Monitoring changes in the corneal TEER, according to the electrophysiologic method with the application of antiallergic eyedrops, is useful for predicting corneal epithelial breakdown caused by their instillation.

Physico-chemical characterization of African urban aerosols (Bamako in Mali and Dakar in Senegal) and their toxic effects in human bronchial epithelial cells: description of a worrying situation.

PubMed

Val, Stéphanie; Liousse, Cathy; Doumbia, El Hadji Thierno; Galy-Lacaux, Corinne; Cachier, Hélène; Marchand, Nicolas; Badel, Anne; Gardrat, Eric; Sylvestre, Alexandre; Baeza-Squiban, Armelle

2013-04-02

The involvement of particulate matter (PM) in cardiorespiratory diseases is now established in developed countries whereas in developing areas such as Africa with a high level of specific pollution, PM pollution and its effects are poorly studied. Our objective was to characterize the biological reactivity of urban African aerosols on human bronchial epithelial cells in relation to PM physico-chemical properties to identify toxic sources. Size-speciated aerosol chemical composition was analyzed in Bamako (BK, Mali, 2 samples with one having desert dust event BK1) and Dakar (DK; Senegal) for Ultrafine UF, Fine F and Coarse C PM. PM reactivity was studied in human bronchial epithelial cells investigating six biomarkers (oxidative stress responsive genes and pro-inflammatory cytokines). PM mass concentrations were mainly distributed in coarse mode (60%) and were impressive in BK1 due to the desert dust event. BK2 and DK samples showed a high content of total carbon characteristic of urban areas. The DK sample had huge PAH quantities in bulk aerosol compared with BK that had more water soluble organic carbon and metals. Whatever the site, UF and F PM triggered the mRNA expression of the different biomarkers whereas coarse PM had little or no effect. The GM-CSF biomarker was the most discriminating and showed the strongest pro-inflammatory effect of BK2 PM. The analysis of gene expression signature and of their correlation with main PM compounds revealed that PM-induced responses are mainly related to organic compounds. The toxicity of African aerosols is carried by the finest PM as with Parisian aerosols, but when considering PM mass concentrations, the African population is more highly exposed to toxic particulate pollution than French population. Regarding the prevailing sources in each site, aerosol biological impacts are higher for incomplete combustion sources resulting from two-wheel vehicles and domestic fires than from diesel vehicles (Dakar). Desert dust

Comparison Test of the Heavy Expanded Mobility Tactical Truck (HEMTT), M978 Tanker

DTIC Science & Technology

1989-02-01

transmission shall include the following (MIL-T-PD-977, para 3.4.5.1): (1) A downshift inhibitor system that prevents driver shift control action from...DIRECTION HI 8 Peg. WIND SPEED: 9 KNOTS TAPE RECORDER: B&K 7006 IOCTAVE ANALYZER I BtK ?ni SOUND LEVEL METER: MICROPHONE: BUK ItISS...ISKY COVER: I CLEAR TAPE RECORDER: B&K 7006 IOCTAVE ANALYZER: I BtK 2131 WIND DIRECTION I ?18 Dee . SOUND LEVEL METER STATIONARY

Polyomavirus Reactivation and Immune Responses to Kidney-Specific Self-Antigens in Transplantation.

PubMed

Seifert, Michael E; Gunasekaran, Muthukumar; Horwedel, Timothy A; Daloul, Reem; Storch, Gregory A; Mohanakumar, Thalachallour; Brennan, Daniel C

2017-04-01

Humoral immune responses against donor antigens are important determinants of long-term transplant outcomes. Reactivation of the polyomavirus BK has been associated with de novo antibodies against mismatched donor HLA antigens in kidney transplantation. The effect of polyomavirus reactivation (BK viremia or JC viruria) on antibodies to kidney-specific self-antigens is unknown. We previously reported excellent 5-year outcomes after minimization of immunosuppression for BK viremia and after no intervention for JC viruria. Here, we report the 10-year results of this trial ( n =193) along with a nested case-control study ( n =40) to explore associations between polyomavirus reactivation and immune responses to the self-antigens fibronectin (FN) and collagen type-IV (Col-IV). Consistent with 5-year findings, subjects taking tacrolimus, compared with those taking cyclosporin, had less acute rejection (11% versus 22%, P =0.05) and graft loss (9% versus 22%, P =0.01) along with better transplant function (eGFR 65±19 versus 50±24 ml/min per 1.73 m 2 , P <0.001) at 10 years. Subjects undergoing immunosuppression reduction for BK viremia had 10-year outcomes similar to those without viremia. In the case-control study, antibodies to FN/Col-IV were more prevalent during year 1 in subjects with polyomavirus reactivation than in those without reactivation (48% versus 11%, P= 0.04). Subjects with antibodies to FN/Col-IV had more acute rejection than did those without these antibodies (38% versus 8%, P =0.02). These data demonstrate the long-term safety and effectiveness of minimizing immunosuppression to treat BK viremia. Furthermore, these results indicate that polyomavirus reactivation associates with immune responses to kidney-specific self-antigens that may increase the risk for acute rejection through unclear mechanisms. Copyright © 2017 by the American Society of Nephrology.

A Case Control Study Reveals that Polyomaviruria Is Significantly Associated with Interstitial Cystitis and Vesical Ulceration

PubMed Central

Winter, Benjamin J.; O'Connell, Helen E.; Bowden, Scott; Carey, Marcus; Eisen, Damon P.

2015-01-01

Objectives To investigate whether polyomaviruses contribute to interstitial cystitis pathogenesis. Subjects and Methods A prospective study was performed with 50 interstitial cystitis cases compared with 50 age-matched, disease-free controls for the frequency of polyomaviruria. Associations between polyomaviruria and disease characteristics were analysed in cases. Polyomavirus in urine and bladder tissue was detected with species (JC virus vs. BK virus) specific, real-time PCR. Results Case patients were reflective of interstitial cystitis epidemiology with age range from 26–88 years (median 58) and female predominance (41/50 F). There was a significant increase in the frequency of polyomavirus shedding between cases and controls (p<0.02). Polyomavirus shedding, in particular BK viruria, was associated with vesical ulceration, a marker of disease severity, among interstitial cystitis cases after adjustment for age and sex (OR 6.8, 95% CI 1.89–24.4). There was a significant association among cases between the presence of BK viruria and response to intravesical Clorpactin therapy (OR 4.50, 95% CI 1.17–17.4). Conclusion The presence of polyomaviruria was found to be associated with the ulcerative form of interstitial cystitis. Clorpactin, which has anti-DNA virus activity, was more likely to improve symptoms in the presence of BK viruria. These data from this pilot study suggest associations between polyomaviruria and interstitial cystitis warranting further investigation. PMID:26325074

Distribution, expression and functional effects of small conductance Ca-activated potassium (SK) channels in rat myometrium.

PubMed

Noble, Karen; Floyd, Rachel; Shmygol, Andre; Shmygol, Anatoly; Mobasheri, A; Wray, Susan

2010-01-01

Calcium-activated potassium channels are important in a variety of smooth muscles, contributing to excitability and contractility. In the myometrium previous work has focussed on the large conductance channels (BK), and the role of small conductance channels (SK) has received scant attention, despite the finding that over-expression of an SK channel isoform (SK3) results in uterine dysfunction and delayed parturition. This study therefore characterises the expression of the three SK channel isoforms (SK1-3) in rat myometrium throughout pregnancy and investigates their effect on cytosolic [Ca] and force and compares this with that of BK channels. Consistent expression of all SK isoform transcripts and clear immunostaining of SK1-3 was found. Inhibition of SK1-3 channels (apamin, scyllatoxin) significantly inhibited outward current, caused membrane depolarisation and elicited action potentials in previously quiescent cells. Apamin or scyllatoxin increased the amplitude of [Ca] and force in spontaneously contracting myometrial strips throughout gestation. The functional effect of SK inhibition was larger than that of BK channel inhibition. Thus we show for the first time that SK1-3 channels are expressed and translated throughout pregnancy and contribute to outward current, regulate membrane potential and hence Ca signals in pregnant rat myometrium. They contribute more to quiescence that BK channels. 2009 Elsevier Ltd. All rights reserved.

Computer Simulations of Bottlebrush Melts and Soft Networks

NASA Astrophysics Data System (ADS)

Cao, Zhen; Carrillo, Jan-Michael; Sheiko, Sergei; Dobrynin, Andrey

We have studied dense bottlebrush systems in a melt and network state using a combination of the molecular dynamics simulations and analytical calculations. Our simulations show that the bottlebrush macromolecules in a melt behave as ideal chains with the effective Kuhn length bK. The bottlebrush induced bending rigidity is due to redistribution of the side chains upon backbone bending. Kuhn length of the bottlebrushes increases with increasing the side-chain degree of polymerization nsc as bK ~nsc0 . 46 . This model of bottlebrush macromolecules is extended to describe mechanical properties of bottlebrush networks in linear and nonlinear deformation regimes. In the linear deformation regime, the network shear modulus scales with the degree of polymerization of the side chains as G0 ~nsc + 1 - 1 as long as the ratio of the Kuhn length to the size of the fully extended bottlebrush backbone between crosslinks, Rmax, is smaller than unity, bK /Rmax < < 1 . Bottlebrush networks with bK /Rmax ~ 1 demonstrate behavior similar to that of networks of semiflexible chains with G0 ~nsc- 0 . 5 . In the nonlinear deformation regime, the deformation dependent shear modulus is a universal function of the first strain invariant I1 and bottlebrush backbone deformation ratio β describing stretching ability of the bottlebrush backbone between crosslinks. Nsf DMR-1409710 DMR-1436201.

Navier-Stokes dynamics on a differential one-form

NASA Astrophysics Data System (ADS)

Story, Troy L.

2006-11-01

After transforming the Navier-Stokes dynamic equation into a characteristic differential one-form on an odd-dimensional differentiable manifold, exterior calculus is used to construct a pair of differential equations and tangent vector(vortex vector) characteristic of Hamiltonian geometry. A solution to the Navier-Stokes dynamic equation is then obtained by solving this pair of equations for the position x^k and the conjugate to the position bk as functions of time. The solution bk is shown to be divergence-free by contracting the differential 3-form corresponding to the divergence of the gradient of the velocity with a triple of tangent vectors, implying constraints on two of the tangent vectors for the system. Analysis of the solution bk shows it is bounded since it remains finite as | x^k | ->,, and is physically reasonable since the square of the gradient of the principal function is bounded. By contracting the characteristic differential one-form with the vortex vector, the Lagrangian is obtained.

Two new bradykinin-related peptides from the venom of the social wasp Protopolybia exigua (Saussure).

PubMed

Mendes, Maria Anita; Palma, Mario Sergio

2006-11-01

Two bradykinin-related peptides (Protopolybiakinin-I and Protopolybiakinin-II) were isolated from the venom of the social wasp Protopolybia exigua by RP-HPLC, and sequenced by Edman degradation method. Peptide sequences of Protopolybiakinin-I and Protopolybiakinin-II were DKNKKPIRVGGRRPPGFTR-OH and DKNKKPIWMAGFPGFTPIR-OH, respectively. Synthetic peptides with identical sequences to the bradykinin-related peptides and their biological functions were characterized. Protopolybiakinin-I caused less potent constriction of the isolated rat ileum muscles than bradykinin (BK). In addition, it caused degranulation of mast cells which was seven times more potent than BK. This peptide causes algesic effects due to the direct activation of B(2)-receptors. Protopolybiakinin-II is not an agonist of rat ileum muscle and had no algesic effects. However, Protopolybiakinin-II was found to be 10 times more potent as a mast cell degranulator than BK. The amino acid sequence of Protopolybiakinin-I is the longest among the known wasp kinins.

An analytical-numerical method for determining the mechanical response of a condenser microphone

PubMed Central

Homentcovschi, Dorel; Miles, Ronald N.

2011-01-01

The paper is based on determining the reaction pressure on the diaphragm of a condenser microphone by integrating numerically the frequency domain Stokes system describing the velocity and the pressure in the air domain beneath the diaphragm. Afterwards, the membrane displacement can be obtained analytically or numerically. The method is general and can be applied to any geometry of the backplate holes, slits, and backchamber. As examples, the method is applied to the Bruel & Kjaer (B&K) 4134 1/2-inch microphone determining the mechanical sensitivity and the mechano-thermal noise for a domain of frequencies and also the displacement field of the membrane for two specified frequencies. These elements compare well with the measured values published in the literature. Also a new design, completely micromachined (including the backvolume) of the B&K micro-electro-mechanical systems (MEM) 1/4-inch measurement microphone is proposed. It is shown that its mechanical performances are very similar to those of the B&K MEMS measurement microphone. PMID:22225026

Pharmacological characterization of the bradykinin B2 receptor: inter-species variability and dissociation between binding and functional responses

PubMed Central

Paquet, J -L; Luccarini, J -M; Fouchet, C; Defrêne, E; Loillier, B; Robert, C; Bélichard, P; Cremers, B; Pruneau, D

1999-01-01

The present study addresses the differences in binding profiles and functional properties of the human and rat bradykinin (BK) B2 receptor using various kinin receptor peptide derivatives as well as the non-peptide receptor antagonists WIN 64338 (phosphonium, [[4-[[2-[[bis(cyclohexylamino)methylene]amino]-3-(2-naphtalenyl)1-oxopropyl]amino]-phenyl]-methyl]tributyl, chloride, monohydro-chloride), and FR173657 (E)-3-(6-acetamido-3-pyridyl)-N-[-N-[2,4-dichloro-3-[(2-methyl-8-quinolinyl)oxymethyl]-phenyl]N-methylamino carbonyl methyl] acrylamide. [3H]-BK bound with a similar affinity to membranes of Chinese hamster ovary cells (CHO-K1) expressing the cloned human (hB2-CHO) or rat (rB2-CHO) B2 receptor, human embryonic intestine cells (INT407) expressing the native B2 receptor, human umbilical vein (HUV) and rat uterus (RU). WIN 64338 and FR173657 bound with a 3.8–6.6 fold and 7.0–16.3 fold higher affinity the rat than the human B2 receptor, respectively. The affinity values of BK derivatives as well as non-peptide antagonists were reduced by 6–23 fold in physiological HBSS compared to low ionic strength TES binding buffer. BK (0.01–3000 nM) increased inositol triphosphates (IP3) levels in hB2-CHO, rB2-CHO and INT407 cells. The B2 receptor antagonist, Hoe 140 (D-Arg0-[ Hyp3, Thi5, D-Tic7, Oic8]-BK) at 10−7 M, significantly shifted to the right the IP3 response curves to BK giving apparent pKB values of 8.56, 9.79 and 8.84 for hB2-CHO, rB2-CHO and INT407 cells, respectively. In human isolated umbilical vein, Hoe 140, D-Arg0-[Hyp3, D-Phe7, Leu8]-BK and NPC 567 had a lower potency in functional assays (pKB 8.18, 5.77 and 5.60, respectively) than expected from their affinity in binding studies (pKi 10.52, 8.64 and 8.27, respectively). FR173657 behaved as a high affinity ligand with pKi values of 8.59 and 9.81 and potent competitive antagonist with pKB values of 7.80 and 8.17 in HUV and RU, respectively. FR173657 bound with a similar affinity the cloned and

A Computer Model for the Transmission Characteristics of Dielectric Radomes

DTIC Science & Technology

1992-03-01

GAUS.F....... 104 APPENDIX D........................105 A. ARGUMENTS: CIRCTHETA. CIRCRHO AND CIRCPHI . . . 105 B. TEST PROGRAM: CIRCSUB.F...ETSCAT(500),EPSCAT(500),ETHF(500),EPHF(500) INTEGER NT,NPHI,CNRHO,CNPHI,NP,SELECTION REAL MODE,BASE,RS,ZP, RHB ,ZHB DATA PI,START,STOP/3.1415926,0.,90...ZH(I)).LT..OO1) ZH(I)=O. IF(ABS(RH(I)).LT..O01) RH(I)=O. ZHB=ZH (I) /BK RHB =RH (I) /BK ZiG (i)=IMP C C ASSIGN SURFACE IMPEDANCE AT THIS POINT. THE

The three-wave equation on the half-line

NASA Astrophysics Data System (ADS)

Xu, Jian; Fan, Engui

2014-01-01

The Fokas method is used to analyze the initial-boundary value problem for the three-wave equation p-{bi-bj}/{ai-aj}p+∑k ({bk-bj}/{ak-aj}-{bi-bk}/{ai-ak})pp=0, i,j,k=1,2,3, on the half-line. Assuming that the solution p(x,t) exists, we show that it can be recovered from its initial and boundary values via the solution of a Riemann-Hilbert problem formulated in the plane of the complex spectral parameter λ.

Doping, Ionic Conductivity and Photothermal Stability of Functionalized DNA for Solar Energy Conversion and Electrochromic Applications

DTIC Science & Technology

2011-06-01

and coworkers 1,2,3,4 . They are renewable and biodegradable materials, recovered from waste in food industry (fruits, animal and fish meat waste) and...charges leads to the change of its absorption spectrum, or in other words to a change of its color . However in most cases the electrolyte used is in...electrodes (cf. Fig. 25). CeO2- TiO2 BK7 BK7 SOLID ELECTROLYTE ITO WO3 ITO Fig. 25. Structure of the used electrochromic cell 21 Figure 26

Economic Analysis of Kiva VCF Treatment System Compared to Balloon Kyphoplasty Using Randomized Kiva Safety and Effectiveness Trial (KAST) Data.

PubMed

Beall, Douglas P; Olan, Wayne J; Kakad, Priyanka; Li, Qianyi; Hornberger, John

2015-01-01

Vertebral compression fractures (VCFs) are the most common osteoporotic fractures and cause persistent pain, kyphotic deformity, weight loss, depression, reduced quality of life, and even death. Current surgical approaches for the treatment of VCF include vertebroplasty (VP) and balloon kyphoplasty (BK). The Kiva® VCF Treatment System (Kiva System) is a next-generation alternative surgical intervention in which a percutaneously introduced nitinol Osteo Coil guidewire is advanced through a deployment cannula and subsequently a PEEK Implant is implanted incrementally and fully coiled in the vertebral body. The Kiva System's effectiveness for the treatment of VCF has been evaluated in a large randomized controlled trial, the Kiva Safety and Effectiveness Trial (KAST). The Kiva System was non-inferior to BK with respect to pain reduction (70.8% vs. 71.8% in Visual Analogue Scale) and physical function restoration (38.1 % vs. 42.2% reduction in Oswestry Disability Index) while using less bone cement. The economic impact of the Kiva system has yet to be analyzed. To analyze hospital resource use and costs of the Kiva System over 2 years for the treatment of VCF compared to BK. A representative US hospital. Economic analysis of the KAST randomized trial, focusing on hospital resource use and costs. The analysis was conducted from a hospital perspective and utilized clinical data from KAST as well as unit-cost data from the published literature. The cost of initial VCF surgery, reoperation cost, device market cost, and other medical costs were compared between the Kiva System and BK. The relative risk reduction rate in adjacent-level fracture with Kiva [31.6% (95% CI: -22.5%, 61.9%)] demonstrated in KAST was used in this analysis. With 304 vertebral augmentation procedures performed in a representative U.S. hospital over 2 years, the Kiva System will produce a direct medical cost savings of $1,118 per patient and $280,876 per hospital. This cost saving with the Kiva

Construction and first characterization of two reciprocal hybrids between LamB from Escherichia coli K12 and Klebsiella pneumoniae.

PubMed

Werts, C; Charbit, A

1993-05-01

The LamB proteins from Klebsiella pneumoniae and Escherichia coli K12 were previously shown to be highly homologous. The most conserved parts correspond to the N-proximal third and to the transmembranous portions of the molecule, while the variability occurred essentially within regions exposed to the cell surface or to the periplasm. Since the two proteins displayed identical in vitro trimer stability and in vivo pore properties, we tested whether the N-terminal parts of the two proteins could be exchanged and still allow the formation of stable and functional maltoporins. For that purpose, we expressed the LamB protein from K. pneumoniae in E. coli K12, and constructed two reciprocal hybrids between LamB from E. coli K12 and LamB from K. pneumoniae. The first hybrid (LamBE.c.-K.p.) is composed of residues 1 to 183 from LamBE.c. followed by residues 184 to 404 from LamBK.p. The second one comprises residues 1 to 183 from LamBK.p., followed by residues 184 to 421 from LamBE.c. (LamBK.p.-E.c.). Both hybrid proteins were correctly incorporated in the outer membrane of E. coli K12. Like the two parental LamB proteins, the two hybrids could be purified by affinity chromatography on a starch-sepharose column. The LamBE.c.-K.p. hybrid formed highly stable trimers, but was strongly impaired in its in vivo maltose transport function (15% of the wild-type level). The trimers formed by LamBK.p.-E.c. hybrid were less stable, but could be detected on the surface of intact cells by four anti-LamBE.c. monoclonal antibodies. This hybrid was also affected in its in vivo maltose transport function (30% of the wild-type level). As expected from the location of the residues critical for phage adsorption, both proteins had lost the phage receptor activity of the E. coli K12 LamB protein. We also examined whether LamBE.c. could form heterotrimers with LamBK.p., LamBK.p.-E.c., and LamBE.c.-K.p. In no case were heterotrimers detected, indicating that both terminal parts of the Lam

Bifunctional fusion proteins containing the sequence of the bradykinin homologue maximakinin: activities at the rat bradykinin B2 receptor.

PubMed

Charest-Morin, Xavier; Lodge, Robert; Marceau, François

2018-05-01

To support bradykinin (BK) B 2 receptor (B 2 R) detection and therapeutic stimulation, we developed and characterized fusion proteins consisting of the BK homolog maximakinin (MK), or variants, positioned at the C-terminus of functional proteins (enhanced green fluorescent protein (EGFP), the peroxidase APEX2, or human serum albumin (HSA)). EGFP-MK loses its reactivity with anti-BK antibodies and molecular mass as it progresses in the endosomal tract of cells expressing rat B 2 Rs (immunoblots, epifluorescence microscopy). APEX2-(NG) 15 -MK is a bona fide agonist of the rat, but not of the human B 2 R (calcium and c-Fos signaling) and is compatible with the cytochemistry reagent TrueBlue (microscopy), a luminol-based reagent, or 3,3',5,5'-tetramethylbenzidine (luminescence or colourimetric B 2 R detection, cell well plate format). APEX2-(NG) 15 -MK is a non-isotopic ligand suitable for drug discovery via binding competition. Affinity-purified secreted forms of HSA fused with peptides possessing the C-terminal MK or BK sequence failed to stimulate the rat B 2 R in the concentration range of 50-600 nmol/L. However, the non-secreted construction myc-HSA-MK is a B 2 R agonist, indicating that protein denaturation made the C-terminal sequence available for receptor binding. Fusion protein ligands of the B 2 R are stable but subjected to slow intracellular inactivation, strong species specificity, and possible steric hindrance between the receptor and large proteins.

Sound side joint contact forces in below knee amputee gait with an ESAR prosthetic foot.

PubMed

Karimi, Mohammad Taghi; Salami, Firooz; Esrafilian, Amir; Heitzmann, Daniel W W; Alimusaj, Merkur; Putz, Cornelia; Wolf, Sebastian I

2017-10-01

The incidence of knee and hip joint osteoarthritis in subjects with below knee amputation (BK) appears significantly higher compared to unimpaired subjects, especially in the intact side. However, it is controversial if constant higher loads on the sound side are one of the major factors for an increased osteoarthritis (OA) incidence in subjects with BK, beside other risk factors, e.g. with respect to metabolism. The aim wasto investigate joint contact forces (JCF) calculated by a musculoskeletal model in the intact side and to compare it with those of unimpaired subjects and to further elucidate in how far increased knee JCF are associated with increased frontal plane knee moments. A group of seven subjects with BK amputation and a group of ten unimpaired subjects were recruited for this study. Gait data were measured by 3D motion capture and force plates. OpenSim software was applied to calculate JCF. Maximum joint angles, ground reaction forces, and moments as well as time distance parameters were determined and compared between groups showing no significant differences, with some JCF components of knee and hip even being slightly smaller in subjects with BK compared to the reference group. This positive finding may be due to the selected ESAR foot. However, other beneficial factors may also have influenced this positive result such as the general good health status of the subjects or the thorough and proper fitting and alignment of the prosthesis. Copyright © 2017 Elsevier B.V. All rights reserved.

Endothelial SK(Ca) and IK(Ca) channels regulate brain parenchymal arteriolar diameter and cortical cerebral blood flow.

PubMed

Hannah, Rachael M; Dunn, Kathryn M; Bonev, Adrian D; Nelson, Mark T

2011-05-01

Calcium-sensitive potassium (K(Ca)) channels have been shown to modulate the diameter of cerebral pial arteries; however, little is known regarding their roles in controlling cerebral parenchymal arterioles (PAs). We explored the function and cellular distribution of small-conductance (SK(Ca)) and intermediate-conductance (IK(Ca)) K(Ca) channels and large-conductance K(Ca) (BK(Ca)) channels in endothelial cells (ECs) and smooth muscle cells (SMCs) of PAs. Both SK(Ca) and IK(Ca) channels conducted the outward current in isolated PA ECs (current densities, ~20 pA/pF and ~28 pA/pF at +40 mV, respectively), but these currents were not detected in PA SMCs. In contrast, BK(Ca) currents were prominent in PA SMCs (~154 pA/pF), but were undetectable in PA ECs. Pressurized PAs constricted to inhibition of SK(Ca) (~16%) and IK(Ca) (~16%) channels, but were only modestly affected by inhibition of BK(Ca) channels (~5%). Blockade of SK(Ca) and IK(Ca) channels decreased resting cortical cerebral blood flow (CBF) by ~15%. NS309 (6,7-dichloro-1H-indole-2,3-dione3-oxime), a SK(Ca)/IK(Ca) channel opener, hyperpolarized PA SMCs by ~27 mV, maximally dilated pressurized PAs, and increased CBF by ~40%. In conclusion, these data show that SK(Ca) and IK(Ca) channels in ECs profoundly modulate PA tone and CBF, whereas BK(Ca) channels in SMCs only modestly influence PA diameter.

Hypoxic remodelling of Ca{sup 2+} stores does not alter human cardiac myofibroblast invasion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riches, K.; Hettiarachchi, N.T.; Porter, K.E.

2010-12-17

Research highlights: {yields} Bradykinin promotes migration and proliferation of myofibroblasts. {yields} Such activity is Ca{sup 2+}-dependent and occurs under hypoxic conditions. {yields} Hypoxia increased myofibroblast Ca{sup 2+} stores but not influx evoked by bradykinin. {yields} Myofibroblast migration and proliferation was unaffected by hypoxia. -- Abstract: Cardiac fibroblasts are the most abundant cell type in the heart, and play a key role in the maintenance and repair of the myocardium following damage such as myocardial infarction by transforming into a cardiac myofibroblast (CMF) phenotype. Repair occurs through controlled proliferation and migration, which are Ca{sup 2+} dependent processes, and often requires themore » cells to operate within a hypoxic environment. Angiotensin converting enzyme (ACE) inhibitors reduce infarct size through the promotion of bradykinin (BK) stability. Although CMF express BK receptors, their activity under the reduced O{sub 2} conditions that occur following infarct are entirely unexplored. Using Fura-2 microfluorimetry on primary human CMF, we found that hypoxia significantly increased the mobilisation of Ca{sup 2+} from intracellular stores in response to BK whilst capacitative Ca{sup 2+} entry (CCE) remained unchanged. The enhanced store mobilisation was due to a striking increase in CMF intracellular Ca{sup 2+}-store content under hypoxic conditions. However, BK-induced CMF migration or proliferation was not affected following hypoxic exposure, suggesting that Ca{sup 2+} influx rather than mobilisation is of primary importance in CMF migration and proliferation.« less

Impact of angiotensin and endothelin converting enzymes and related bradykinin on renal functions in L-NAME hypertensive rats

NASA Astrophysics Data System (ADS)

Omar, Ali Zainal; Maulood, Ismail M.

2017-09-01

The renin-angiotensin system (RAS), one of the most important hormonal systems, controls the kidney functions by regulating fluid volume, and electrolyte balance. The current study included the effects of kinin-kallikrein system (KKS) and its interaction with both angiotensin converting enzyme (ACE) and endothelin converting enzyme (ECE) on some of kidney function test parameters. In the present experiment, rats were divided into six groups, the first group was infused with normal saline, the second group was L-NG-Nitroarginine methyl ester (L-NAME) treated rats, third group was bradykinin (BK), forth group was captopril (ACEi), fifth group was phosphoramidon (ECEi), sixth group was a combination of BK with phosphoramidon. L-NAME was intravenously infused for one hour to develop systematic hypertension in male rats. After one hour of infusion, the results showed that L-NAME significantly increased serum creatinine. While, it decreased glomerular filtration rate (GFR), and K+ excretion rate. Moreover, BK increased packed cell volume PCV%, serum creatinine and K+ ion concentration. While, it reduced GFR, serum Ca+2 ion concentration, K+ and Na+ excretion rates. On the other hand, captopril infusion showed its effect by reduction in GFR, serum Ca+2 ion and electrolyte excretion rates. Phosphoramidon an ECEi dramatically reduced serum Ca+2 ion, but it increased pH, GFR and Ca+2 excretion rate. The results suggested that BK and Captopril each alone severely reduces GFR value. Interestingly, inhibition of ET-1 production via phosphoramidon could markedly elevate GFR values.

Remarkably High Stability of Late Actinide Dioxide Cations: Extending Chemistry to Pentavalent Berkelium and Californium.

PubMed

Dau, Phuong D; Vasiliu, Monica; Peterson, Kirk A; Dixon, David A; Gibson, John K

2017-12-06

Actinyl chemistry is extended beyond Cm to BkO 2 + and CfO 2 + through transfer of an O atom from NO 2 to BkO + or CfO + , establishing a surprisingly high lower limit of 73 kcal mol -1 for the dissociation energies, D[O-(BkO + )] and D[O-(CfO + )]. CCSD(T) computations are in accord with the observed reactions, and characterize the newly observed dioxide ions as linear pentavalent actinyls; these being the first Bk and Cf species with oxidation states above IV. Computations of actinide dioxide cations AnO 2 + for An=Pa to Lr reveal an unexpected minimum for D[O-(CmO + )]. For CmO 2 + , and AnO 2 + beyond EsO 2 + , the most stable structure has side-on bonded η 2 -(O 2 ), as An III peroxides for An=Cm and Lr, and as An II superoxides for An=Fm, Md, and No. It is predicted that the most stable structure of EsO 2 + is linear [O=Es V =O] + , einsteinyl, and that FmO 2 + and MdO 2 + , like CmO 2 + , also have actinyl(V) structures as local energy minima. The results expand actinide oxidation state chemistry, the realm of the distinctive actinyl moiety, and the non-periodic character towards the end of the periodic table. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Darcy Permeability of Hollow Fiber Bundles Used in Blood Oxygenation Devices

PubMed Central

Pacella, Heather E.; Eash, Heidi J.; Federspiel, William J.

2011-01-01

Many industrial and biomedical devices (e.g. blood oxygenators and artificial lungs) use bundles of hollow fiber membranes for separation processes. Analyses of flow and mass transport within the shell-side of the fiber bundles most often model the bundle for simplicity as a packed bed or porous media, using a Darcy permeability coefficient estimated from the Blake-Kozeny equation to account for viscous drag from the fibers. In this study, we developed a simple method for measuring the Darcy permeability of hollow fiber membrane bundles and evaluated how well the Blake-Kozeny (BK) equation predicted the Darcy permeability for these bundles. Fiber bundles were fabricated from commercially available Celgard® ×30-240 fiber fabric (300 μm outer diameter fibers @ 35 and 54 fibers/inch) and from a fiber fabric with 193 μm fibers (61 fibers/inch). The fiber bundles were mounted to the bottom of an acrylic tube and Darcy permeability was determined by measuring the elapsed time for a column of glycerol solution to flow through a fiber bundle. The ratio of the measured Darcy permeability to that predicted from the BK equation varied from 1.09 to 0.56. A comprehensive literature review suggested a modified BK equation with the “constant” correlated to porosity. This modification improved the predictions of the BK equation, with the ratio of measured to predicted permeability varying from 1.13 to 0.84. PMID:22927706

Structure and genomic organization of the human B1 receptor gene for kinins (BDKRB1).

PubMed

Bachvarov, D R; Hess, J F; Menke, J G; Larrivée, J F; Marceau, F

1996-05-01

Two subtypes of mammalian bradykinin receptors, B1 and B2 (BDKRB1 and BDKRB2), have been defined based on their pharmacological properties. The B1 type kinin receptors have weak affinity for intact BK or Lys-BK but strong affinity for kinin metabolites without the C-terminal arginine (e.g., des-Arg9-BK and Lys-des-Arg9-BK, also called des-Arg10-kallidin), which are generated by kininase I. The B1 receptor expression is up-regulated following tissue injury and inflammation (hyperemia, exudation, hyperalgesia, etc.). In the present study, we have cloned and sequenced the gene encoding human B1 receptor from a human genomic library. The human B1 receptor gene contains three exons separated by two introns. The first and the second exon are noncoding, while the coding region and the 3'-flanking region are located entirely on the third exon. The exon-intron arrangement of the human B1 receptor gene shows significant similarity with the genes encoding the B2 receptor subtype in human, mouse, and rat. Sequence analysis of the 5'-flanking region revealed the presence of a consensus TATA box and of numerous candidate transcription factor binding sequences. Primer extension experiments have shown the existence of multiple transcription initiation sites situated downstream and upstream from the consensus TATA box. Genomic Southern blot analysis indicated that the human B1 receptor is encoded by a single-copy gene.

DNA from BK Virus and JC Virus and from KI, WU, and MC Polyomaviruses as Well as from Simian Virus 40 Is Not Detected in Non-UV-Light-Associated Primary Malignant Melanomas of Mucous Membranes ▿

PubMed Central

Giraud, Géraldine; Ramqvist, Torbjörn; Ragnarsson-Olding, Boel; Dalianis, Tina

2008-01-01

The single most important causative factor for malignant melanomas of the skin is UV radiation. However, this is not true for melanomas on body surfaces sheltered from the sun; thus, it is important to seek new causative factors of melanoma genesis. Human papillomaviruses and gammaherpesviruses are associated with human skin cancer; for example, human papillomavirus types 5 and 8 are associated with epidermodysplasia verruciformis, and human herpesvirus 8 is associated with Kaposi's sarcoma. Recently, a newly described human polyomavirus, Merkel cell polyomavirus (MCPyV), has been associated with Merkel cell carcinoma, an unusual form of neurotropic skin cancer. Moreover, melanocytes are of neuroepithelial origin. This background impelled us to investigate if human polyomavirus DNA could play a role in the development of extracutaneous melanomas. Sixty-four extracutaneous melanomas were initially collected and dissected. Of these, 38 could be successfully used for further testing for the presence of the five human polyomaviruses known so far—BK virus (BKV), JC virus (JCV), KI polyomavirus (KIPyV), WU polyomavirus (WUPyV), and MCPyV—and of simian virus 40 (SV40). No polyomavirus DNA could be detected in any of the samples tested by use of a nested PCR detecting BKV, JCV, and SV40; a newly designed PCR detecting KIPyV and WUPyV; or a newly designed PCR for MCPyV. We conclude that since no human polyomavirus DNA was detected in primary malignant melanomas on non-sun-exposed body surfaces, these polyomaviruses presumably are not major factors for the development of extracutaneous melanomas. PMID:18768658

Non-selectivity of new bradykinin antagonists for B1 receptors.

PubMed

Rhaleb, N E; Gobeil, F; Regoli, D

1992-01-01

Two new B1 receptor antagonists, [Hyp3,Thi5,DTic7,Oic8]desArg9-BK and DArg[Hyp3,Thi5,DTic7,Oic8]desArg9-BK were tested in vitro on the rabbit jugular vein and the guinea pig ileum (preparations containing B2 receptors) and on the rabbit aorta (preparation containing B1 receptors) for pharmacological characterization. The results indicate that both compounds are antagonists on both B1 and B2 receptors, are competitive and discriminate between B2A and B2B receptor subtypes.

Decoy-state reference-frame-independent quantum key distribution with both source errors and statistical fluctuations

NASA Astrophysics Data System (ADS)

Liu, Kang; Li, Jian; Zhu, Jian-Rong; Zhang, Chun-Mei; Wang, Qin

2017-12-01

Not Available Project supported by the National Key Research and Development Program of China (Grant No. 2017YFA0304100), the National Natural Science Foundation of China (Grant Nos. 61475197, 61590932, 11774180, and 61705110), the Natural Science Foundation of the Jiangsu Higher Education Institutions (Grant Nos. 15KJA120002 and 17KJB140016), the Outstanding Youth Project of Jiangsu Province, China (Grant No. BK20150039), the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20170902), and the Science Fund from the Nanjing University of Posts and Telecommunications, China (Grant No. NY217006).

Coagulase-negative staphylococci isolated from ocular wound infections after laser refractive surgery: attachment to and accumulation on soft contact lenses.

PubMed

Faghri, Jamshid; Razavi, Mohamad Reza

2009-03-01

Disposable soft contact lenses that are commonly used after laser refractive surgery are known to be colonized by bacteria and play a key role in Bacterial Keraitis (BK) pathogenesis. Coagulase-negative staphylococci (CoNS) have been found to be the most common pathogen involved in this postoperative infection. In this study a rapid and a simple assay was developed for studying attachment and accumulation of CoNS on soft contact lenses in vitro using [3H] thymidine. Thirty-five isolates of CoNS were obtained from 27 laser refractive surgery patients. Twenty-five of these thirty-five CoNS were isolated in multiple cultures. Ten CoNS were isolated in cultures from patients who underwent reoperation. The assay was optimized using a biofilm-producing strain, S. epidermidis RP62A, which was subcultured overnight at 37 degrees C on blood agar medium. Quantitative determination of biofilm production was tested. Presence of the genes icaADB and icaD was determined in all isolates. All isolates were biochemically analyzed using the Phene Plate (PhP) system modified for typing of CoNS. The CoNS isolates were further characterized to species level using ID32Staph.Mann-Whitney rank sum test and chi-square test were used to identify statistical differences in adherence, index, antibiotic susceptibility patterns, and biofilm production or presence of the ica operon between clinically significant isolates and non-postoperative BK isolates. No differences in attachment and accumulation were found between isolates causing BK after laser refractive surgery and contaminant isolates. In addition, there were no differences in the distribution of the ica operon between the two groups, as determined by polymerase chain reaction. Nevertheless, the ability to produce biofilm was found to be present significantly more frequently among BK isolates than among non-postoperative BK isolates. This study shows that the method using radioactive thymidine to analyze adherence of CoNS to soft

N-methyl-D-aspartate receptors and large conductance calcium-sensitive potassium channels inhibit the release of opioid peptides that induce mu-opioid receptor internalization in the rat spinal cord.

PubMed

Song, B; Marvizón, J C G

2005-01-01

Endogenous opioids in the spinal cord play an important role in nociception, but the mechanisms that control their release are poorly understood. To simultaneously detect all opioids able to activate the mu-opioid receptor, we measured mu-opioid receptor internalization in rat spinal cord slices stimulated electrically or chemically to evoke opioid release. Electrical stimulation of the dorsal horn in the presence of peptidase inhibitors produced mu-opioid receptor internalization in half of the mu-opioid receptor neurons. This internalization was rapidly abolished by N-methyl-D-aspartate (IC50=2 microM), and N-methyl-D-aspartate antagonists prevented this effect. mu-Opioid receptor internalization evoked by high K+ or veratridine was also inhibited by N-methyl-D-aspartate receptor activation. N-methyl-D-aspartate did not affect mu-opioid receptor internalization induced by exogenous endomorphins, confirming that the effect of N-methyl-D-aspartate was on opioid release. We hypothesized that this inhibition was mediated by large conductance Ca2+-sensitive K+ channels BK(Ca2+). Indeed, inhibition by N-methyl-D-aspartate was prevented by tetraethylammonium and by the selective BK(Ca2+) blockers paxilline, penitrem A and verruculogen. Paxilline did not increase mu-opioid receptor internalization in the absence of N-methyl-D-aspartate, indicating that it does not produce an increase in opioid release unrelated to the inhibition by N-methyl-d-aspartate. The BK(Ca2+) involved appears to be a subtype with slow association kinetics for iberiotoxin, which was effective only with long incubations. The BK(Ca2+) opener NS-1619 also inhibited the evoked mu-opioid receptor internalization, and iberiotoxin prevented this effect. We concluded that Ca2+ influx through N-methyl-D-aspartate receptors causes the opening of BK(Ca2+) and hyperpolarization in opioid-containing dorsal horn neurons, resulting in the inhibition of opioid release. Since mu-opioid receptors in the dorsal horn

N-METHYL-d-ASPARTATE RECEPTORS AND LARGE CONDUCTANCE CALCIUM-SENSITIVE POTASSIUM CHANNELS INHIBIT THE RELEASE OF OPIOID PEPTIDES THAT INDUCE μ-OPIOID RECEPTOR INTERNALIZATION IN THE RAT SPINAL CORD

PubMed Central

SONG, B.; MARVIZÓN, J. C. G.

2006-01-01

Endogenous opioids in the spinal cord play an important role in nociception, but the mechanisms that control their release are poorly understood. To simultaneously detect all opioids able to activate the μ-opioid receptor, we measured μ-opioid receptor internalization in rat spinal cord slices stimulated electrically or chemically to evoke opioid release. Electrical stimulation of the dorsal horn in the presence of peptidase inhibitors produced μ-opioid receptor internalization in half of the μ-opioid receptor neurons. This internalization was rapidly abolished by N-methyl-d-aspartate (IC50=2 μM), and N-methyl-d-aspartate antagonists prevented this effect. μ-Opioid receptor internalization evoked by high K+ or veratridine was also inhibited by N-methyl-d-aspartate receptor activation. N-methyl-d-aspartate did not affect μ-opioid receptor internalization induced by exogenous endomorphins, confirming that the effect of N-methyl-d-aspartate was on opioid release. We hypothesized that this inhibition was mediated by large conductance Ca2+-sensitive K+ channels BK(Ca2+). Indeed, inhibition by N-methyl-d-aspartate was prevented by tetraethylammonium and by the selective BK(Ca2+) blockers paxilline, penitrem A and verruculogen. Paxilline did not increase μ-opioid receptor internalization in the absence of N-methyl-d-aspartate, indicating that it does not produce an increase in opioid release unrelated to the inhibition by N-methyl-d-aspartate. The BK(Ca2+) involved appears to be a subtype with slow association kinetics for iberiotoxin, which was effective only with long incubations. The BK(Ca2+) opener NS-1619 also inhibited the evoked μ-opioid receptor internalization, and iberiotoxin prevented this effect. We concluded that Ca2+ influx through N-methyl-d-aspartate receptors causes the opening of BK(Ca2+) and hyperpolarization in opioid-containing dorsal horn neurons, resulting in the inhibition of opioid release. Since μ-opioid receptors in the dorsal horn

SSR240612 [(2R)-2-[((3R)-3-(1,3-benzodioxol-5-yl)-3-[[(6-methoxy-2-naphthyl)sulfonyl]amino]propanoyl)amino]-3-(4-[[2R,6S)-2,6-dimethylpiperidinyl]methyl]phenyl)-N-isopropyl-N-methylpropanamide hydrochloride], a new nonpeptide antagonist of the bradykinin B1 receptor: biochemical and pharmacological characterization.

PubMed

Gougat, Jean; Ferrari, Bernard; Sarran, Lionel; Planchenault, Claudine; Poncelet, Martine; Maruani, Jeanne; Alonso, Richard; Cudennec, Annie; Croci, Tiziano; Guagnini, Fabio; Urban-Szabo, Katalin; Martinolle, Jean-Pierre; Soubrié, Philippe; Finance, Olivier; Le Fur, Gérard

2004-05-01

The biochemical and pharmacological properties of a novel non-peptide antagonist of the bradykinin (BK) B(1) receptor, SSR240612 [(2R)-2-[((3R)-3-(1,3-benzodioxol-5-yl)-3-[[(6-methoxy-2-naphthyl)sulfonyl]amino]propanoyl)amino]-3-(4-[[2R,6S)-2,6-dimethylpiperidinyl]methyl]phenyl)-N-isopropyl-N-methylpropanamide hydrochloride] were evaluated. SSR240612 inhibited the binding of [(3)H]Lys(0)-des-Arg(9)-BK to the B(1) receptor in human fibroblast MRC5 and to recombinant human B(1) receptor expressed in human embryonic kidney cells with inhibition constants (K(i)) of 0.48 and 0.73 nM, respectively. The compound selectivity for B(1) versus B(2) receptors was in the range of 500- to 1000-fold. SSR240612 inhibited Lys(0)-desAr(9)-BK (10 nM)-induced inositol monophosphate formation in human fibroblast MRC5, with an IC(50) of 1.9 nM. It also antagonized des-Arg(9)-BK-induced contractions of isolated rabbit aorta and mesenteric plexus of rat ileum with a pA(2) of 8.9 and 9.4, respectively. Antagonistic properties of SSR240612 were also demonstrated in vivo. SSR240612 inhibited des-Arg(9)-BK-induced paw edema in mice (3 and 10 mg/kg p.o. and 0.3 and 1 mg/kg i.p.). Moreover, SSR240612 reduced capsaicin-induced ear edema in mice (0.3, 3 and 30 mg/kg p.o.) and tissue destruction and neutrophil accumulation in the rat intestine following splanchnic artery occlusion/reperfusion (0.3 mg/kg i.v.). The compound also inhibited thermal hyperalgesia induced by UV irradiation (1 and 3 mg/kg p.o.) and the late phase of nociceptive response to formalin in rats (10 and 30 mg/kg p.o.). Finally, SSR240612 (20 and 30 mg/kg p.o.) prevented neuropathic thermal pain induced by sciatic nerve constriction in the rat. In conclusion, SSR240612 is a new, potent, and orally active specific non-peptide bradykinin B(1) receptor antagonist.

By Hook or by MOOC: Lessons Learned and the Road Ahead

NASA Astrophysics Data System (ADS)

Korsunsky, Boris; Li, Clara

2017-03-01

As online education has exploded in the past decade, the number of physics and physics-related massive open online courses (or MOOCs, to use the industry lingo) has grown substantially as well. Several such courses aim at high school students, especially those involved in the AP Physics program. One of us (BK) was involved in creating two such courses, both of which use the edX platform: MechCx, a full AP Physics course, as part of the group led by David Pritchard at MIT and a smaller-scale MechC101x, where BK was the sole author and developer. CL, a senior at Weston High School in 2016-17, took MechC101x during its first run in the summer of 2015 before taking BK's AP Physics C class in 2015-16. The purpose of this article is to present the data obtained from the maiden run of MechC101x, analyze the advantages and disadvantages of MOOCs compared to face-to-face courses, and to lay out some principles for the effective use of MOOCs in physics education.

Predicting positive parity B$$_s$$ mesons from lattice QCD

DOE PAGES

Lang, C. B.; Mohler, Daniel; Prelovsek, Sasa; ...

2015-08-18

We determine the spectrum of B s 1P states using lattice QCD. For the B s1(5830) and B s2*(5840) mesons, the results are in good agreement with the experimental values. Two further mesons are expected in the quantum channels J P = 0 + and 1 + near the BK and B*K thresholds. A combination of quark–antiquark and B(*) meson–Kaon interpolating fields are used to determine the mass of two QCD bound states below the B(*)K threshold, with the assumption that mixing with B s (*)η and isospin-violating decays to B s (*)π are negligible. We predict a J Pmore » = 0 + bound state Bs0 with mass mBs0 = 5.711(13)(19) GeV. In addition, with further assumptions motivated theoretically by the heavy quark limit, a bound state with m Bs1=5.750(17)(19) GeV is predicted in the J P = 1 + channel. The results from our first principles calculation are compared to previous model-based estimates.« less

Benzo[a]pyrene and Benzo[k]fluoranthene in Some Processed Fish and Fish Products

PubMed Central

Olatunji, Olatunde S.; Fatoki, Olalekan S.; Opeolu, Beatrice O.; Ximba, Bhekumusa J.

2015-01-01

In this study, the concentration levels of the probable carcinogenic PAH fractions, benzo[a]pyrene (BaP) and benzo[k]fluoranthrene (BkF) in fillets of some processed fish species were investigated. Fish species comprising Merluccius poli (hake), Tyrsites atun (snoek), Seriola lalandi (yellow-tail) and Brama brama (angel fish) were bought in fish shops at Gordon’s Bay, Western Cape, South Africa. The fish were gutted, filleted and prepared for edibility by frying, grilling and boiling. Polycyclic aromatic hydrocarbons were extracted from each homogenized fish sample, cleaned-up using solid phase extraction (SPE), and analysed for the PAH fractions, BaP and BkF using a Gas Chromatograph coupled with a Flame Ionization Detector (GC-FID). The sum of the two PAHs (∑2PAH) i.e., BaP and BkF ranged between 0.56 and 1.46 µg/kg, in all boiled, grilled and fried fish species. The fried fish extracts showed significantly higher (p < 0.05) abundance of ∑2PAH, than grilled and boiled fish. Dietary safety and PAHs toxicity was also discussed. PMID:25607603

An analytical-numerical method for determining the mechanical response of a condenser microphone.

PubMed

Homentcovschi, Dorel; Miles, Ronald N

2011-12-01

The paper is based on determining the reaction pressure on the diaphragm of a condenser microphone by integrating numerically the frequency domain Stokes system describing the velocity and the pressure in the air domain beneath the diaphragm. Afterwards, the membrane displacement can be obtained analytically or numerically. The method is general and can be applied to any geometry of the backplate holes, slits, and backchamber. As examples, the method is applied to the Bruel & Kjaer (B&K) 4134 1/2-inch microphone determining the mechanical sensitivity and the mechano-thermal noise for a domain of frequencies and also the displacement field of the membrane for two specified frequencies. These elements compare well with the measured values published in the literature. Also a new design, completely micromachined (including the backvolume) of the B&K micro-electro-mechanical systems (MEM) 1/4-inch measurement microphone is proposed. It is shown that its mechanical performances are very similar to those of the B&K MEMS measurement microphone. © 2011 Acoustical Society of America

Contact activation: a revision.

PubMed

Schmaier, A H

1997-07-01

In conclusion, a revised view of the contact system has been presented. This system has little to do with the initiation of hemostasis. Like lupus anticoagulants, deficiencies of contact proteins give prolonged APTTs but may be risk factors for thrombosis. BK from kininogens is a potent modulator of vascular biology inducing vasodilation, tissue plasminogen activator release, and prostacyclin liberation. Kininogens, themselves, are selective inhibitors of alpha-thrombin-induced platelet activation preventing alpha-thrombin from cleaving the cloned thrombin receptor after arginine41. Kininogens' alpha-thrombin inhibitory activity exists in intact kininogens, BK, and all of BK's breakdown products. HK also is the pivotal protein for contact protein assembly on endothelium. It is the receptor for prekallikrein which when bound to HK becomes activated to kallikrein by an endothelial cell enzyme system independent of activated forms of plasma factor XII. Prekallikrein activation on endothelial cells results in kinetically favorable single chain urokinase and plasminogen activation. Thus the "physiologic, negatively charged surface" for contact system activation is really the assembly of these proteins on cell membranes and activation by membrane-associated enzymes.

Cloning, expression in Pichia pastoris, and characterization of a thermostable GH5 mannan endo-1,4-beta-mannosidase from Aspergillus niger BK01.

PubMed

Do, Bien-Cuong; Dang, Thi-Thu; Berrin, Jean-Guy; Haltrich, Dietmar; To, Kim-Anh; Sigoillot, Jean-Claude; Yamabhai, Montarop

2009-11-13

Mannans are key components of lignocellulose present in the hemicellulosic fraction of plant primary cell walls. Mannan endo-1,4-beta-mannosidases (1,4-beta-D-mannanases) catalyze the random hydrolysis of beta-1,4-mannosidic linkages in the main chain of beta-mannans. Biodegradation of beta-mannans by the action of thermostable mannan endo-1,4-beta-mannosidase offers significant technical advantages in biotechnological industrial applications, i.e. delignification of kraft pulps or the pretreatment of lignocellulosic biomass rich in mannan for the production of second generation biofuels, as well as for applications in oil and gas well stimulation, extraction of vegetable oils and coffee beans, and the production of value-added products such as prebiotic manno-oligosaccharides (MOS). A gene encoding mannan endo-1,4-beta-mannosidase or 1,4-beta-D-mannan mannanohydrolase (E.C. 3.2.1.78), commonly termed beta-mannanase, from Aspergillus niger BK01, which belongs to glycosyl hydrolase family 5 (GH5), was cloned and successfully expressed heterologously (up to 243 microg of active recombinant protein per mL) in Pichia pastoris. The enzyme was secreted by P. pastoris and could be collected from the culture supernatant. The purified enzyme appeared glycosylated as a single band on SDS-PAGE with a molecular mass of approximately 53 kDa. The recombinant beta-mannanase is highly thermostable with a half-life time of approximately 56 h at 70 degrees C and pH 4.0. The optimal temperature (10-min assay) and pH value for activity are 80 degrees C and pH 4.5, respectively. The enzyme is not only active towards structurally different mannans but also exhibits low activity towards birchwood xylan. Apparent Km values of the enzyme for konjac glucomannan (low viscosity), locust bean gum galactomannan, carob galactomannan (low viscosity), and 1,4-beta-D-mannan (from carob) are 0.6 mg mL-1, 2.0 mg mL-1, 2.2 mg mL-1 and 1.5 mg mL-1, respectively, while the kcat values for these

Compartmentalized beta subunit distribution determines characteristics and ethanol sensitivity of somatic, dendritic, and terminal large-conductance calcium-activated potassium channels in the rat central nervous system.

PubMed

Wynne, P M; Puig, S I; Martin, G E; Treistman, S N

2009-06-01

Neurons are highly differentiated and polarized cells, whose various functions depend upon the compartmentalization of ion channels. The rat hypothalamic-neurohypophysial system (HNS), in which cell bodies and dendrites reside in the hypothalamus, physically separated from their nerve terminals in the neurohypophysis, provides a particularly powerful preparation in which to study the distribution and regional properties of ion channel proteins. Using electrophysiological and immunohistochemical techniques, we characterized the large-conductance calcium-activated potassium (BK) channel in each of the three primary compartments (soma, dendrite, and terminal) of HNS neurons. We found that dendritic BK channels, in common with somatic channels but in contrast to nerve terminal channels, are insensitive to iberiotoxin. Furthermore, analysis of dendritic BK channel gating kinetics indicates that they, like somatic channels, have fast activation kinetics, in contrast to the slow gating of terminal channels. Dendritic and somatic channels are also more sensitive to calcium and have a greater conductance than terminal channels. Finally, although terminal BK channels are highly potentiated by ethanol, somatic and dendritic channels are insensitive to the drug. The biophysical and pharmacological properties of somatic and dendritic versus nerve terminal channels are consistent with the characteristics of exogenously expressed alphabeta1 versus alphabeta4 channels, respectively. Therefore, one possible explanation for our findings is a selective distribution of auxiliary beta1 subunits to the somatic and dendritic compartments and beta4 to the terminal compartment. This hypothesis is supported immunohistochemically by the appearance of distinct punctate beta1 or beta4 channel clusters in the membrane of somatic and dendritic or nerve terminal compartments, respectively.

Use of deuterium labeling by high-temperature solid-state hydrogen-exchange reaction for mass spectrometric analysis of bradykinin biotransformation.

PubMed

Kopylov, Arthur T; Myasoedov, Nikolay F; Dadayan, Alexander K; Zgoda, Victor G; Medvedev, Alexei E; Zolotarev, Yurii A

2016-06-15

Studies of molecular biodegradation by mass spectrometry often require synthetic compounds labeled with stable isotopes as internal standards. However, labeling is very expensive especially when a large number of compounds are needed for analysis of biotransformation. Here we describe an approach for qualitative and quantitative analysis using bradykinin (BK) and its in vitro degradation metabolites as an example. Its novelty lies in the use of deuterated peptides which are obtained by a high-temperature solid-state exchange (HSCIE) reaction. Deuterated and native BK were analyzed by positive electrospray ionization high-resolution mass spectrometry (ESI-HRMS) using an Orbitrap Fusion mass spectrometer. High-energy collision-induced dissociation (HCD) experiments were performed on [M+H](+) and [M+2H](2+) ions in targeted-MS(2) mode with adjusted normalized HCD value. After the HSCIE reaction, each amino acid residue of the deuterated peptide contained deuterium atoms and the average degree of substitution was 5.5 atoms per the peptide molecule. The deuterated peptide demonstrated the same chromatographic mobility as the unlabeled counterpart, and lack of racemization during substitution with deuterium. Deuterium-labeled and unlabeled BKs were incubated with human plasma and their corresponding fragments BK(1-5) and BK(1-7), well known as the major metabolites, were detected. Quantitative assays demonstrated applicability of the heavy peptide for both sequencing and quantification of generated fragments. Applicability of the HSCIE deuterated peptide for analysis of routes of its degradation has been shown in in vitro experiments. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.