The rebirth of interest in renal tubular function.

PubMed

Lowenstein, Jerome; Grantham, Jared J

2016-06-01

The measurement of glomerular filtration rate by the clearance of inulin or creatinine has evolved over the past 50 years into an estimated value based solely on plasma creatinine concentration. We have examined some of the misconceptions and misunderstandings of the classification of renal disease and its course, which have followed this evolution. Furthermore, renal plasma flow and tubular function, which in the past were estimated by the clearance of the exogenous aryl amine, para-aminohippurate, are no longer measured. Over the past decade, studies in experimental animals with reduced nephron mass and in patients with reduced renal function have identified small gut-derived, protein-bound uremic retention solutes ("uremic toxins") that are poorly filtered but are secreted into the lumen by organic anion transporters (OATs) in the proximal renal tubule. These are not effectively removed by conventional hemodialysis or peritoneal dialysis. Residual renal function, urine produced in patients with advanced renal failure or undergoing dialysis treatment, may represent, at least in part, secretion of fluid and uremic toxins, such as indoxyl sulfate, mediated by proximal tubule OATs and might serve as a useful survival function. In light of this new evidence of the physiological role of proximal tubule OATs, we suggest that measurement of renal tubular function and renal plasma flow may be of considerable value in understanding and managing chronic kidney disease. Data obtained in normal subjects indicate that renal plasma flow and renal tubular function might be measured by the clearance of the endogenous aryl amine, hippurate. Copyright © 2016 the American Physiological Society.

The urinary excretion of metformin, ceftizoxime and ofloxacin in high serum creatinine rats: Can creatinine predict renal tubular elimination?

PubMed

Ma, Yan-Rong; Zhou, Yan; Huang, Jing; Qin, Hong-Yan; Wang, Pei; Wu, Xin-An

2018-03-01

The renal excretion of creatinine and most drugs are the net result of glomerular filtration and tubular secretion, and their tubular secretions are mediated by individual transporters. Thus, we hypothesized that the increase of serum creatinine (SCr) levels attributing to inhibiting tubular transporters but not glomerular filtration rate (GFR) could be used to evaluate the tubular excretion of drugs mediated by identical or partial overlap transporter with creatinine. In this work, we firstly developed the creatinine excretion inhibition model with normal GFR by competitively inhibiting tubular transporters, and investigated the renal excretion of metformin, ceftizoxime and ofloxacin in vivo and in vitro. The results showed that the 24-hour urinary excretion of metformin and ceftizoxime in model rats were decreased by 25% and 17% compared to that in control rats, respectively. The uptake amount and urinary excretion of metformin and ceftizoxime could be inhibited by creatinine in renal cortical slices and isolated kidney perfusion. However, the urinary excretion of ofloxacin was not affected by high SCr. These results showed that the inhibition of tubular creatinine transporters by high SCr resulted to the decrease of urinary excretion of metformin and ceftizoxime, but not ofloxacin, which implied that the increase of SCr could also be used to evaluate the tubular excretion of drugs mediated by identical or partial overlap transporter with creatinine in normal GFR rats. Copyright © 2018 Elsevier Inc. All rights reserved.

Autophagy activation promotes removal of damaged mitochondria and protects against renal tubular injury induced by albumin overload.

PubMed

Tan, Jin; Wang, Miaohong; Song, Shuling; Miao, Yuyang; Zhang, Qiang

2018-01-10

Proteinuria (albuminuria) is an important cause of aggravating tubulointerstitial injury. Previous studies have shown that autophagy activation can alleviate renal tubular epithelial cell injury caused by urinary protein, but the mechanism is not clear. Here, we investigated the role of clearance of damaged mitochondria in this protective effect. We found that albumin overload induces a significant increase in turnover of LC3-II and decrease in p62 protein level in renal proximal tubular (HK-2) cells in vitro. Albumin overload also induces an increase in mitochondrial damage. ALC, a mitochondrial torpent, alleviates mitochondrial damage induced by albumin overload and also decreases autophagy, while mitochondrial damage revulsant CCCP further increases autophagy. Furthermore, pretreatment of HK-2 cells with rapamycin reduced the amount of damaged mitochondria and the level of apoptosis induced by albumin overload. In contrast, blocking autophagy with chloroquine exerted an opposite effect. Taken together, our results indicated autophagy activation promotes removal of damaged mitochondria and protects against renal tubular injury caused by albumin overload. This further confirms previous research that autophagy activation is an adaptive response in renal tubular epithelial cells after urinary protein overload.

Glucagon-like peptide 1 receptor expression in primary porcine proximal tubular cells.

PubMed

Schlatter, P; Beglinger, C; Drewe, J; Gutmann, H

2007-06-07

GLP-1 is secreted into the circulation after food intake. The main biological effects of GLP-1 include stimulation of glucose dependent insulin secretion and induction of satiety feelings. Recently, it was demonstrated in rats and humans that GLP-1 can stimulate renal excretion of sodium. Based on these data, the existence of a renal GLP-1 receptor (GLP-1R) was postulated. However, the exact localization of the GLP-1R and the mechanism of this GLP-1 action have not yet been investigated. Primary porcine proximal tubular cells were isolated from porcine kidneys. Expression of GLP-1R was measured at the mRNA level by quantitative RT-PCR. Protein expression of GLP-1R was verified with immunocytochemistry, immunohistochemistry and Western blot analysis. Functional studies included transport assessments of sodium and glucose using three different GLP-1 concentrations (200 pM, 2 nM and 20 nM), 200 pM exendin-4 (GLP-1 analogue) and an inhibitor of the dipeptidylpeptidase IV (DPPIV) enzyme (P32/98 at 10 microM). Finally, the expression of NHE3, the predominant Na(+)/H(+) exchanger in proximal tubular cells, was also investigated. GLP-1R, NHE3 and DPPIV were expressed at the mRNA level in porcine proximal tubular kidney cells. GLP-1R expression was confirmed at the protein level. Staining of human and pig kidney cortex revealed that GLP-1R was predominantly expressed in proximal tubular cells. Functional assays demonstrated an inhibition of sodium re-absorption with GLP-1 after 3 h of incubation. Exendin-4 and GLP-1 in combination with P32/98 co-administration had no clear influence on glucose and sodium uptake and transport. GLP-1R is functionally expressed in porcine proximal tubular kidney cells. Addition of GLP-1 to these cells resulted in a reduced sodium re-absorption. GLP-1 had no effect on glucose re-absorption. We conclude that GLP-1 modulates sodium homeostasis in the kidney most likely through a direct action via its GLP-1R in proximal tubular cells.

Intra-tubular hydrodynamic forces influence tubulo-interstitial fibrosis in the kidney

PubMed Central

Rohatgi, Rajeev; Flores, Daniel

2010-01-01

Purpose of review Renal epithelial cells respond to mechanical stimuli with immediate transduction events (e.g., activation of ion channels), intermediate biological responses (e.g., changes in gene expression), and long term cellular adaptation (e.g., protein expression). Progressive renal disease is characterized by disturbed glomerular hydrodynamics that contributes to glomerulosclerosis, but, how intra-tubular biomechanical forces contribute to tubulo-interstital inflammation and fibrosis is poorly understood. Recent findings In vivo and in vitro models of obstructive uropathy demonstrate that tubular stretch induces robust expression of transforming growth factor β-1 (TGFβ-1), activation of tubular apoptosis, and induction of NF-κB signaling which contribute to the inflammatory and fibrotic milieu. Non-obstructive structural kidney diseases associated with nephron loss follow a course characterized by compensatory increases of single nephron glomerular filtration rate and tubular flow rate. Resulting increases in tubular fluid shear stress (FSS) reduce tissue-plasminogen activator and urokinase enzymatic activity which diminishes breakdown of extracellular matrix. In models of high dietary Na intake, which increase tubular flow, urinary TGFβ-1 concentrations and renal mitogen activated protein kinase activity are increased. Summary In conclusion, intra-tubular biomechanical forces, stretch and FSS, generate changes in intracellular signaling and gene expression that contribute to the pathobiology of obstructive, and non-obstructive kidney disease. PMID:19851105

Comprehensive clinical approach to renal tubular acidosis.

PubMed

Sharma, Sonia; Gupta, Ankur; Saxena, Sanjiv

2015-08-01

Renal tubular acidosis (RTA) is essentially characterized by normal anion gap and hyperchloremic metabolic acidosis. It is important to understand that despite knowing the disease for 60-70 years, complexities in the laboratory tests and their interpretation still make clinicians cautious to diagnose and label types of tubular disorder. Hence, we are writing this mini-review to emphasize on the step wise approach to RTA with some understanding on its basic etiopathogenesis. This will definitely help to have an accurate interpretation of urine and blood reports in correlation with the clinical condition. RTA can be a primary or secondary defect and results either due to abnormality in bicarbonate ion absorption or hydrogen ion secretion. Primary defects are common in children due to gene mutation or idiopathic nature while secondary forms are more common in adults. We are focusing and explaining here in this review all the clinical and laboratory parameters which are essential for making the diagnosis of RTA and excluding the extrarenal causes of hyperchloremic, normal anion gap metabolic acidosis.

Kindlin-2 regulates renal tubular cell plasticity by activation of Ras and its downstream signaling.

PubMed

Wei, Xiaofan; Wang, Xiang; Xia, Yang; Tang, Yan; Li, Feng; Fang, Weigang; Zhang, Hongquan

2014-01-01

Kindlin-2 is an adaptor protein that contributes to renal tubulointerstitial fibrosis (TIF). Epithelial-to-mesenchymal transition (EMT) in tubular epithelial cells was regarded as one of the key events in TIF. To determine whether kindlin-2 is involved in the EMT process, we investigated its regulation of EMT in human kidney tubular epithelial cells (TECs) and explored the underlying mechanism. In this study, we found that overexpression of kindlin-2 suppressed epithelial marker E-cadherin and increased the expression of fibronectin and the myofibroblast marker α-smooth muscle actin (SMA). Kindlin-2 significantly activated ERK1/2 and Akt, and inhibition of ERK1/2 or Akt reversed kindlin-2-induced EMT in human kidney TECs. Mechanistically, kindlin-2 interacted with Ras and son of sevenless (Sos)-1. Furthermore, overexpression of kindlin-2 increased Ras activation through recruiting Sos-1. Treatment with a Ras inhibitor markedly repressed kindlin-2-induced ERK1/2 and Akt activation, leading to restraint of EMT. We further demonstrated that knockdown of kindlin-2 inhibited EGF-induced Ras-Sos-1 interaction, resulting in reduction of Ras activation and suppression of EMT stimulated by EGF. Importantly, we found that depletion of kindlin-2 significantly inhibited activation of ERK1/2 and Akt signaling in mice with unilateral ureteral obstruction. We conclude that kindlin-2, through activating Ras and the downstream ERK1/2 and Akt signaling pathways, plays an important role in regulating renal tubular EMT and could be a potential therapeutic target for the treatment of fibrotic kidney diseases.

Proteases induce secretion of collagenase and plasminogen activator by fibroblasts

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

Werb, Z.; Aggeler, J.

1978-04-01

We have observed that treatment of rabbit synovial fibroblasts with proteolytic enzymes can induce secretion of collagenase (EC 3.4.24.7) and plasminogen activator (EC 3.4.21.-). Cells treated for 2 to 24 hr with plasmin, trypsin, chymotrypsin, pancreatic elastase, papain, bromelain, thermolysin, or ..cap alpha..-protease but not with thrombin or neuraminidase secreted detectable amounts of collagenase within 16 to 48 hr. Treatment of fibroblasts with trypsin also induced secretion of plasminogen activator. Proteases initiated secretion of collagenase (up to 20 units per 10/sup 6/ cells per 24 hr) only when treatment produced decreased cell adhesion. Collagenase production did not depend on continuedmore » presence of proteolytic activity or on subsequent cell adhesion, spreading, or proliferation. Routine subculturing with crude trypsin also induced collagenase secretion by cells. Secretion of collagenase was prevented and normal spreading was obtained if the trypsinized cells were placed into medium containing fetal calf serum. Soybean trypsin inhibitor, ..cap alpha../sub 1/-antitrypsin, bovine serum albumin, collagen, and fibronectin did not inhibit collagenase production. Although proteases that induced collagenase secretion also removed surface glycoprotein, the kinetics of induction of cell protease secretion were different from those for removal of fibronectin. Physiological inducers of secretion of collagenase and plasminogen activator by cells have not been identified. These results suggest that extracellular proteases in conjunction with plasma proteins may govern protease secretion by cells.« less

Rab6a/a’ Are Important Golgi Regulators of Pro-Inflammatory TNF Secretion in Macrophages

PubMed Central

Micaroni, Massimo; Stanley, Amanda C.; Khromykh, Tatiana; Venturato, Juliana; Wong, Colin X. F.; Lim, Jet P.; Marsh, Brad J.; Storrie, Brian; Gleeson, Paul A.; Stow, Jennifer L.

2013-01-01

Lipopolysaccharide (LPS)-activated macrophages secrete pro-inflammatory cytokines, including tumor necrosis factor (TNF) to elicit innate immune responses. Secretion of these cytokines is also a major contributing factor in chronic inflammatory disease. In previous studies we have begun to elucidate the pathways and molecules that mediate the intracellular trafficking and secretion of TNF. Rab6a and Rab6a' (collectively Rab6) are trans-Golgi-localized GTPases known for roles in maintaining Golgi structure and Golgi-associated trafficking. We found that induction of TNF secretion by LPS promoted the selective increase of Rab6 expression. Depletion of Rab6 (via siRNA and shRNA) resulted in reorganization of the Golgi ribbon into more compact structures that at the resolution of electron microcopy consisted of elongated Golgi stacks that likely arose from fusion of smaller Golgi elements. Concomitantly, the delivery of TNF to the cell surface and subsequent release into the media was reduced. Dominant negative mutants of Rab6 had similar effects in disrupting TNF secretion. In live cells, Rab6–GFP were localized on trans-Golgi network (TGN)-derived tubular carriers demarked by the golgin p230. Rab6 depletion and inactive mutants altered carrier egress and partially reduced p230 membrane association. Our results show that Rab6 acts on TNF trafficking at the level of TGN exit in tubular carriers and our findings suggest Rab6 may stabilize p230 on the tubules to facilitate TNF transport. Both Rab6 isoforms are needed in macrophages for Golgi stack organization and for the efficient post-Golgi transport of TNF. This work provides new insights into Rab6 function and into the role of the Golgi complex in cytokine secretion in inflammatory macrophages. PMID:23437303

Rab6a/a' are important Golgi regulators of pro-inflammatory TNF secretion in macrophages.

PubMed

Micaroni, Massimo; Stanley, Amanda C; Khromykh, Tatiana; Venturato, Juliana; Wong, Colin X F; Lim, Jet P; Marsh, Brad J; Storrie, Brian; Gleeson, Paul A; Stow, Jennifer L

2013-01-01

Lipopolysaccharide (LPS)-activated macrophages secrete pro-inflammatory cytokines, including tumor necrosis factor (TNF) to elicit innate immune responses. Secretion of these cytokines is also a major contributing factor in chronic inflammatory disease. In previous studies we have begun to elucidate the pathways and molecules that mediate the intracellular trafficking and secretion of TNF. Rab6a and Rab6a' (collectively Rab6) are trans-Golgi-localized GTPases known for roles in maintaining Golgi structure and Golgi-associated trafficking. We found that induction of TNF secretion by LPS promoted the selective increase of Rab6 expression. Depletion of Rab6 (via siRNA and shRNA) resulted in reorganization of the Golgi ribbon into more compact structures that at the resolution of electron microcopy consisted of elongated Golgi stacks that likely arose from fusion of smaller Golgi elements. Concomitantly, the delivery of TNF to the cell surface and subsequent release into the media was reduced. Dominant negative mutants of Rab6 had similar effects in disrupting TNF secretion. In live cells, Rab6-GFP were localized on trans-Golgi network (TGN)-derived tubular carriers demarked by the golgin p230. Rab6 depletion and inactive mutants altered carrier egress and partially reduced p230 membrane association. Our results show that Rab6 acts on TNF trafficking at the level of TGN exit in tubular carriers and our findings suggest Rab6 may stabilize p230 on the tubules to facilitate TNF transport. Both Rab6 isoforms are needed in macrophages for Golgi stack organization and for the efficient post-Golgi transport of TNF. This work provides new insights into Rab6 function and into the role of the Golgi complex in cytokine secretion in inflammatory macrophages.

Micro-Tubular Fuel Cells

NASA Technical Reports Server (NTRS)

Kimble, Michael C.; Anderson, Everett B.; Jayne, Karen D.; Woodman, Alan S.

2004-01-01

Micro-tubular fuel cells that would operate at power levels on the order of hundreds of watts or less are under development as alternatives to batteries in numerous products - portable power tools, cellular telephones, laptop computers, portable television receivers, and small robotic vehicles, to name a few examples. Micro-tubular fuel cells exploit advances in the art of proton-exchange-membrane fuel cells. The main advantage of the micro-tubular fuel cells over the plate-and-frame fuel cells would be higher power densities: Whereas the mass and volume power densities of low-pressure hydrogen-and-oxygen-fuel plate-and-frame fuel cells designed to operate in the targeted power range are typically less than 0.1 W/g and 0.1 kW/L, micro-tubular fuel cells are expected to reach power densities much greater than 1 W/g and 1 kW/L. Because of their higher power densities, micro-tubular fuel cells would be better for powering portable equipment, and would be better suited to applications in which there are requirements for modularity to simplify maintenance or to facilitate scaling to higher power levels. The development of PEMFCs has conventionally focused on producing large stacks of cells that operate at typical power levels >5 kW. The usual approach taken to developing lower-power PEMFCs for applications like those listed above has been to simply shrink the basic plate-and-frame configuration to smaller dimensions. A conventional plate-and-frame fuel cell contains a membrane/electrode assembly in the form of a flat membrane with electrodes of the same active area bonded to both faces. In order to provide reactants to both electrodes, bipolar plates that contain flow passages are placed on both electrodes. The mass and volume overhead of the bipolar plates amounts to about 75 percent of the total mass and volume of a fuel-cell stack. Removing these bipolar plates in the micro-tubular fuel cell significantly increases the power density.

Tubular graphite cones.

PubMed

Zhang, Guangyu; Jiang, Xin; Wang, Enge

2003-04-18

We report the synthesis of tubular graphite cones using a chemical vapor deposition method. The cones have nanometer-sized tips, micrometer-sized roots, and hollow interiors with a diameter ranging from about 2 to several tens of nanometers. The cones are composed of cylindrical graphite sheets; a continuous shortening of the graphite layers from the interior to the exterior makes them cone-shaped. All of the tubular graphite cones have a faceted morphology. The constituent graphite sheets have identical chiralities of a zigzag type across the entire diameter, imparting structural control to tubular-based carbon structures. The tubular graphite cones have potential for use as tips for scanning probe microscopy, but with greater rigidity and easier mounting than currently used carbon nanotubes.

Apical targeting of the formin Diaphanous in Drosophila tubular epithelia

PubMed Central

Rousso, Tal; Shewan, Annette M; Mostov, Keith E; Schejter, Eyal D; Shilo, Ben-Zion

2013-01-01

Apical secretion from epithelial tubes of the Drosophila embryo is mediated by apical F-actin cables generated by the formin-family protein Diaphanous (Dia). Apical localization and activity of Dia are at the core of restricting F-actin formation to the correct membrane domain. Here we identify the mechanisms that target Dia to the apical surface. PI(4,5)P2 levels at the apical membrane regulate Dia localization in both the MDCK cyst model and in Drosophila tubular epithelia. An N-terminal basic domain of Dia is crucial for apical localization, implying direct binding to PI(4,5)P2. Dia apical targeting also depends on binding to Rho1, which is critical for activation-induced conformational change, as well as physically anchoring Dia to the apical membrane. We demonstrate that binding to Rho1 facilitates interaction with PI(4,5)P2 at the plane of the membrane. Together these cues ensure efficient and distinct restriction of Dia to the apical membrane. DOI: http://dx.doi.org/10.7554/eLife.00666.001 PMID:23853710

Tubule-Derived Wnts Are Required for Fibroblast Activation and Kidney Fibrosis.

PubMed

Zhou, Dong; Fu, Haiyan; Zhang, Lu; Zhang, Ke; Min, Yali; Xiao, Liangxiang; Lin, Lin; Bastacky, Sheldon I; Liu, Youhua

2017-08-01

Cell-cell communication via Wnt ligands is necessary in regulating embryonic development and has been implicated in CKD. Because Wnt ligands are ubiquitously expressed, the exact cellular source of the Wnts involved in CKD remains undefined. To address this issue, we generated two conditional knockout mouse lines in which Wntless (Wls), a dedicated cargo receptor that is obligatory for Wnt secretion, was selectively ablated in tubular epithelial cells or interstitial fibroblasts. Blockade of Wnt secretion by genetic deletion of Wls in renal tubules markedly inhibited myofibroblast activation and reduced renal fibrosis after unilateral ureteral obstruction. This effect associated with decreased activation of β -catenin and downstream gene expression and preserved tubular epithelial integrity. In contrast, fibroblast-specific deletion of Wls exhibited little effect on the severity of renal fibrosis after obstructive or ischemia-reperfusion injury. In vitro , incubation of normal rat kidney fibroblasts with tubule-derived Wnts promoted fibroblast proliferation and activation. Furthermore, compared with kidney specimens from patients without CKD, biopsy specimens from patients with CKD also displayed increased expression of multiple Wnt proteins, predominantly in renal tubular epithelium. These results illustrate that tubule-derived Wnts have an essential role in promoting fibroblast activation and kidney fibrosis via epithelial-mesenchymal communication. Copyright © 2017 by the American Society of Nephrology.

Tubular urate transporter gene polymorphisms differentiate patients with gout who have normal and decreased urinary uric acid excretion.

PubMed

Torres, Rosa J; de Miguel, Eugenio; Bailén, Rebeca; Banegas, José R; Puig, Juan G

2014-09-01

Primary gout has been associated with single-nucleotide polymorphisms (SNP) in several tubular urate transporter genes. No study has assessed the association of reabsorption and secretion urate transporter gene SNP with gout in a single cohort of documented primary patients with gout carefully subclassified as normoexcretors or underexcretors. Three reabsorption SNP (SLC22A12/URAT1, SLC2A9/GLUT9, and SLC22A11/OAT4) and 2 secretion transporter SNP (SLC17A1/NPT1 and ABCG2/BRCP) were studied in 104 patients with primary gout and in 300 control subjects. The patients were subclassified into normoexcretors and underexcretors according to their serum and 24-h urinary uric acid levels under strict conditions of dietary control. Compared with control subjects, patients with gout showed different allele distributions of the 5 SNP analyzed. However, the diagnosis of underexcretor was only positively associated with the presence of the T allele of URAT1 rs11231825, the G allele of GLUT9 rs16890979, and the A allele of ABCG2 rs2231142. The association of the A allele of ABCG2 rs2231142 in normoexcretors was 10 times higher than in underexcretors. The C allele of NPT1 rs1165196 was only significantly associated with gout in patients with normal uric acid excretion. Gout with uric acid underexcretion is associated with transporter gene SNP related mainly to tubular reabsorption, whereas uric acid normoexcretion is associated only with tubular secretion SNP. This finding supports the concept of distinctive mechanisms to account for hyperuricemia in patients with gout with reduced or normal uric acid excretion.

Calcineurin inhibitors recruit protein kinases JAK2 and JNK, TLR signaling and the UPR to activate NF-κB-mediated inflammatory responses in kidney tubular cells

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

González-Guerrero, Cristian, E-mail: cristian.gonzalez@fjd.es; Ocaña-Salceda, Carlos, E-mail: carlos.ocana@fjd.es; Berzal, Sergio, E-mail: sberzal@fjd.es

The calcineurin inhibitors (CNIs) cyclosporine (CsA) and tacrolimus are key drugs in current immunosuppressive regimes for solid organ transplantation. However, they are nephrotoxic and promote death and profibrotic responses in tubular cells. Moreover, renal inflammation is observed in CNI nephrotoxicity but the mechanisms are poorly understood. We have now studied molecular pathways leading to inflammation elicited by the CNIs in cultured and kidney tubular cells. Both CsA and tacrolimus elicited a proinflammatory response in tubular cells as evidenced by a transcriptomics approach. Transcriptomics also suggested several potential pathways leading to expression of proinflammatory genes. Validation and functional studies disclosed thatmore » in tubular cells, CNIs activated protein kinases such as the JAK2/STAT3 and TAK1/JNK/AP-1 pathways, TLR4/Myd88/IRAK signaling and the Unfolded Protein Response (UPR) to promote NF-κB activation and proinflammatory gene expression. CNIs also activated an Nrf2/HO-1-dependent compensatory response and the Nrf2 activator sulforaphane inhibited JAK2 and JNK activation and inflammation. A murine model of CsA nephrotoxicity corroborated activation of the proinflammatory pathways identified in cell cultures. Human CNIs nephrotoxicity was also associated with NF-κB, STAT3 and IRE1α activation. In conclusion, CNIs recruit several intracellular pathways leading to previously non-described proinflammatory actions in renal tubular cells. Identification of these pathways provides novel clues for therapeutic intervention to limit CNIs nephrotoxicity. - Highlights: • Molecular mechanisms modulating CNI renal inflammation were investigated. • Kinases, immune receptors and ER stress mediate the inflammatory response to CNIs. • Several intracellular pathways activate NF-κB in CNIs-treated tubular cells. • A NF-κB-dependent cytokine profile characterizes CNIs-induced inflammation. • CNI nephrotoxicity was associated to

Expandable tubulars for use in geologic structures

DOEpatents

Spray, Jeffery A.; Svedeman, Steven; Walter, David; Mckeighan, Peter; Siebanaler, Shane; Dewhurst, Peter; Hobson, Steven; Foss, Doug; Wirz, Holger; Sharpe, Aaron; Apostal, Michael

2014-08-12

An expandable tubular includes a plurality of leaves formed from sheet material that have curved surfaces. The leaves extend around a portion or fully around the diameter of the tubular structure. Some of the adjacent leaves of the tubular are coupled together. The tubular is compressed to a smaller diameter so that it can be inserted through previously deployed tubular assemblies. Once the tubular is properly positioned, it is deployed and coupled or not coupled to a previously deployed tubular assembly. The tubular is useful for all types of wells and boreholes.

Gastric acid secretion: activation and inhibition.

PubMed Central

Sachs, G.; Prinz, C.; Loo, D.; Bamberg, K.; Besancon, M.; Shin, J. M.

1994-01-01

Peripheral regulation of gastric acid secretion is initiated by the release of gastrin from the G cell. Gastrin then stimulates the cholecystokinin-B receptor on the enterochromaffin-like cell beginning a calcium signaling cascade. An exocytotic release of histamine follows with concomitant activation of a C1- current. The released histamine begins the H2-receptor mediated sequence of events in the parietal cell, which results in activation of the gastric H+/K+ - ATPase. This enzyme is the final common pathway of acid secretion. The H+/K+ - ATPase is composed of two subunits: the larger alpha-subunit couples ion transport to hydrolysis of ATP, the smaller beta-subunit is required for appropriate assembly of the holoenzyme. Both the membrane and extracytoplasmic domain contain the ion transport pathway, and therefore, this region is the target for the antisecretory drugs of the post-H2 era. The 100 kDa alpha-subunit has probably 10 membrane spanning segments with, therefore, five extracytoplasmic loops. The 35 kDA beta-subunit has a single membrane spanning segment, and most of this protein is extracytoplasmic with the six or seven N glycosylation consensus sequences occupied. Omeprazole is an acid-accumulated, acid-activated, prodrug that binds covalently to two cysteine residues at positions 813 (or 822) and 892, accessible from the acidic face of the pump. Lansoprazole binds to cys321, 813 (or 822) and 892; pantoprazole binds to cys813 and 822. The common binding site for these drugs (cys813 or 822) is responsible for the inhibition of acid transport. Covalent inhibition of the acid pump improves control of acid secretion, but since the effective half life of the inhibition in man is about 48 hr, full inhibition of acid secretion, perhaps necessary for eradication of Helicobacter pylori in combination with a single antibiotic, will require prolongation of the effect of this class of drug. PMID:7502535

Hydraulic pressure inducing renal tubular epithelial-myofibroblast transdifferentiation in vitro.

PubMed

Li, Fei-yan; Xie, Xi-sheng; Fan, Jun-ming; Li, Zi; Wu, Jiang; Zheng, Rong

2009-09-01

The effects of hydraulic pressure on renal tubular epithelial-myofibroblast transdifferentiation (TEMT) were investigated. We applied hydraulic pressure (50 cm H2O) to normal rat kidney tubular epithelial cells (NRK52E) for different durations. Furthermore, different pressure magnitudes were applied to cells. The morphology, cytoskeleton, and expression of myofibroblastic marker protein and transforming growth factor-beta1 (TGF-beta1) of NRK52E cells were examined. Disorganized actin filaments and formation of curling clusters in actin were seen in the cytoplasm of pressurized cells. We verified that de novo expression of alpha-smooth muscle actin induced by pressure, which indicated TEMT, was dependent on both the magnitude and duration of pressure. TGF-beta1 expression was significantly upregulated under certain conditions, which implies that the induction of TEMT by hydraulic pressure is related with TGF-beta1. We illustrate for the first time that hydraulic pressure can induce TEMT in a pressure magnitude- and duration-dependent manner, and that this TEMT is accompanied by TGF-beta1 secretion.

Distal renal tubular dysfunction: a common feature in calcium stone formers.

PubMed

Megevand, M; Favre, H

1984-12-01

Distal renal tubular acidosis has been reported as an uncommon cause of urinary calcium stone disease. However, this defect appears to be more frequent when appropriate tests are performed systematically. Twenty-nine patients with recurrent calcium stones have been separated into three groups: normocalciuric (group A), renal hypercalciuric (group B) and absorptive hypercalciuric (group C). Distal tubular functions were investigated by the (urine-blood) pCO2 gradient and by an ammonium chloride test. (Urine-blood) pCO2 gradient was (mean +/- SEM), 3.33 +/- 0.59 in group A, 2.95 +/- 0.34 in group B and 3.31 +/- 0.58 kPa in group C. All these values differ significantly from those observed in controls (4.11 +/- 0.28 kPa; P less than 0.05). After 3 days of ammonium chloride loading, ammonium excretion averaged 54.7 +/- 4.2 in group A, 54.4 +/- 4.3 in group B and 64.3 +/- 5.5 mumol min-1 in group C. Values obtained in the first two groups were significantly lower than that achieved by control subjects (76.4 +/- 14.9 mumol min-1). It is concluded that tubular dysfunctions defined as impairments in hydrogen ion secretion and ammonium excretion after an acid challenge are a common feature of the urinary calcium stone disease and play a contributory role in its pathogenesis.

Role of AMP-activated protein kinase in kidney tubular transport, metabolism, and disease.

PubMed

Rajani, Roshan; Pastor-Soler, Nuria M; Hallows, Kenneth R

2017-09-01

AMP-activated protein kinase (AMPK) is a metabolic sensor that regulates cellular energy balance, transport, growth, inflammation, and survival functions. This review explores recent work in defining the effects of AMPK on various renal tubular epithelial ion transport proteins as well as its role in kidney injury and repair in normal and disease states. Recently, several groups have uncovered additional functions of AMPK in the regulation of kidney and transport proteins. These new studies have focused on the role of AMPK in the kidney in the setting of various diseases such as diabetes, which include evaluation of the effects of the hyperglycemic state on podocyte and tubular cell function. Other recent studies have investigated how reduced kidney mass, polycystic kidney disease (PKD), and fibrosis affect AMPK activation status. A general theme of several conditions that lead to chronic kidney disease (CKD) is that AMPK activity is abnormally suppressed relative to that in normal kidneys. Thus, the idea that AMPK activation may be a therapeutic strategy to slow down the progression of CKD has emerged. In addition to drugs such as metformin and 5-aminoimidazole-4-carboxamide ribonucleotide that are classically used as AMPK activators, recent studies have identified the therapeutic potential of other compounds that function at least partly as AMPK activators, such as salicylates, statins, berberine, and resveratrol, in preventing the progression of CKD. AMPK in the kidney plays a unique role at the crossroads of energy metabolism, ion and water transport, inflammation, and stress. Its potential role in modulating recovery from vs. progression of acute and chronic kidney injury has been the topic of recent research findings. The continued study of AMPK in kidney physiology and disease has improved our understanding of these physiological and pathological processes and offers great hope for therapeutic avenues for the increasing population at risk to develop kidney

Glomerular filtration rate estimation from plasma creatinine after inhibition of tubular secretion: relevance of the creatinine assay.

PubMed

Kemperman, F A; Silberbusch, J; Slaats, E H; van Zanten, A P; Weber, J A; Krediet, R T; Arisz, L

1999-05-01

Estimation of glomerular filtration rate (GFR) from plasma creatinine concentration after inhibition of tubular creatinine secretion with cimetidine provides a good assessment in patients with various nephropathies and with non-insulin-dependent diabetes mellitus (NIDDM). The aim of this study was to compare cimetidine-aided GFR estimations using various creatinine assays. In 30 outpatients with NIDDM GFR was measured as the urinary clearance of continuously infused [125I]iothalamate. Plasma creatinine concentration was analysed after oral cimetidine with an alkaline picrate (AP) method, with an enzymatic (PAP) assay and with HPLC. GFR estimations were calculated with the Cockcroft Gault formula (CG). AP creatinine concentrations were significantly higher than PAP or HPLC values. GFR estimations by AP (CG(AP) 66 +/- 19 ml/min/1.73 m2, mean SD) were significantly lower than GFR (89 +/- 30), whereas CG(PAP) (85 +/- 30) and CG(HPLC) (84 +/- 34 ml/min/1.73 m2) were not. Bland and Altman analysis showed a difference between CG(AP) and GFR of -22.4 +/- 17.7 ml/min/1.73 m2; this difference becomes larger when the GFR increases. The difference between CG and GFR was only -3.8 +/- 14.8 ml/min/1.73 m2 for PAP and -4.4 +/- 17.5 ml/min/1.73 m2 for HPLC, without any systematic difference. A good assessment of the GFR from plasma creatinine after cimetidine administration is possible when creatinine is measured with an enzymatic assay or with the less convenient HPLC method. The more widespread and cheaper alkaline picrate assay is not suitable for GFR-estimation.

Tubular secretion of creatinine in autosomal dominant polycystic kidney disease: consequences for cross-sectional and longitudinal performance of kidney function estimating equations.

PubMed

Spithoven, Edwin M; Meijer, Esther; Boertien, Wendy E; Sinkeler, Steef J; Tent, Hilde; de Jong, Paul E; Navis, Gerjan; Gansevoort, Ron T

2013-09-01

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by renal tubular cell proliferation and dedifferentiation, which may influence tubular secretion of creatinine (CCr[TS]). Diagnostic test study. We therefore investigated CCr(TS) in patients with ADPKD and controls and studied consequences for the performance of glomerular filtration rate (GFR) estimating equations. In patients with ADPKD and healthy controls, we measured GFR as (125)I-iothalamate clearance while simultaneously determining creatinine clearance. 24-hour urinary albumin excretion. In 121 patients with ADPKD (56% men; mean age, 40 ± 11 [SD] years) and 215 controls (48% men; mean age, 53 ± 10 years), measured GFR (mGFR) was 78 ± 30 and 98 ± 17 mL/min/1.73 m(2), respectively, and CCr(TS) was 15.9 ± 10.8 and 10.9 ± 10.6 mL/min/1.73 m(2), respectively (P < 0.001). The higher CCr(TS) in patients with ADPKD remained significant after adjustment for covariates and appeared to be dependent on mGFR. Correlation and accuracy between mGFR and CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) estimated GFR (eGFR) were 0.95 and 99%, respectively; between mGFR and MDRD (Modification of Diet in Renal Disease) Study eGFR, they were 0.93 and 97%, respectively. Values for bias, precision, and accuracy were similar or slightly better than in controls. In addition, change in mGFR during 3 years of follow-up in 45 patients with ADPKD correlated well with change in eGFR. Cross-sectional, single center. CCr(TS) in patients with ADPKD is higher than that in controls, but this effect is limited and observed at only high-normal mGFR. Consequently, the CKD-EPI and MDRD Study equations perform relatively well in estimating GFR and change in GFR in patients with ADPKD. Copyright © 2013 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Sat1 is dispensable for active oxalate secretion in mouse duodenum

PubMed Central

Ko, Narae; Knauf, Felix; Jiang, Zhirong; Markovich, Daniel

2012-01-01

Mice deficient for the apical membrane oxalate transporter SLC26A6 develop hyperoxalemia, hyperoxaluria, and calcium oxalate stones due to a defect in intestinal oxalate secretion. However, the nature of the basolateral membrane oxalate transport process that operates in series with SLC26A6 to mediate active oxalate secretion in the intestine remains unknown. Sulfate anion transporter-1 (Sat1 or SLC26A1) is a basolateral membrane anion exchanger that mediates intestinal oxalate transport. Moreover, Sat1-deficient mice also have a phenotype of hyperoxalemia, hyperoxaluria, and calcium oxalate stones. We, therefore, tested the role of Sat1 in mouse duodenum, a tissue with Sat1 expression and SLC26A6-dependent oxalate secretion. Although the active secretory flux of oxalate across mouse duodenum was strongly inhibited (>90%) by addition of the disulfonic stilbene DIDS to the basolateral solution, secretion was unaffected by changes in medium concentrations of sulfate and bicarbonate, key substrates for Sat1-mediated anion exchange. Inhibition of intracellular bicarbonate production by acetazolamide and complete removal of bicarbonate from the buffer also produced no change in oxalate secretion. Finally, active oxalate secretion was not reduced in Sat1-null mice. We conclude that a DIDS-sensitive basolateral transporter is involved in mediating oxalate secretion across mouse duodenum, but Sat1 itself is dispensable for this process. PMID:22517357

Neural control of renal tubular sodium reabsorption of the dog.

PubMed

DiBona, G F

1978-04-01

The evidence supporting a role for direct neurogenic control of renal tubular sodium reabsorption is reviewed. Electron microscopic and fluorescence histochemical studies demonstrate adrenergic nerve terminals in direct contact with basement membranes of mammalian renal tubular epithelial cells. Low level direct or baroreceptor reflex stimulation of renal sympathetic nerves produces an increase in renal tubular sodium reabsorption without alterations in glomerular filtration rate, renal blood flow, or intrarenal distribution of blood flow. The antinatriuresis is prevented by prior treatment of the kidney with guanethidine or phenoxybenzamine. Possible indirect mediation of the antinatriuresis by other humoral agents known to be released from the kidney upon renal nerve stimulation (angiotensin II, prostaglandin) was excluded by experiments with appropriate blocking agents. Reflex diminutions in renal nerve activity (left atrial distention, stellate ganglion stimulation) produce a decrease in renal tubular sodium reabsorption independent of glomerular filtration rate or renal blood flow. The anatomically described adrenergic innervation of the renal tubules participates in the direct regulation of renal tubular sodium reabsorption.

Emodin ameliorates cisplatin-induced apoptosis of rat renal tubular cells in vitro by activating autophagy

PubMed Central

Liu, Hong; Gu, Liu-bao; Tu, Yue; Hu, Hao; Huang, Yan-ru; Sun, Wei

2016-01-01

Aim: A previous report shows that emodin extracted from the Chinese herbs rhubarb and giant knotweed rhizome can ameliorate the anticancer drug cisplatin-induced injury of HEK293 cells. In this study, we investigated whether and how emodin could protect renal tubular epithelial cells against cisplatin-induced nephrotoxicity in vitro. Methods: The viability and apoptosis of normal rat renal tubular epithelial cells (NRK-52E) were detected using formazan assay and flow cytometry analysis, respectively. The expression levels of cleaved caspase-3, autophagy maker LC3 I/II, and AMPK/mTOR signaling pathway-related proteins were measured with Western blot analysis. The changes of morphology and RFP-LC3 fluorescence were observed under microscopy. Results: Cisplatin (10-50 μmol/L) dose-dependently induced cell damage and apoptosis in NRK-52E cells, whereas emodin (10 and 100 μmol/L) significantly ameliorated cisplatin-induced cell damage, apoptosis and caspase-3 cleavage. Emodin dose-dependently increased LC3-II levels and induced RFP-LC3-containing punctate structures in NRK-52E cells. Furthermore, the protective effects of emodin were abolished by bafilomycin A1 (10 nmol/L), and mimicked by rapamycin (100 nmol/L). Moreover, emodin increased the phosphorylation of AMPK and suppressed the phosphorylation of mTOR. The AMPK inhibitor compound C (10 μmol/L) not only abolished emodin-induced autophagy activation, but also emodin-induced anti-apoptotic effects. Conclusion: Emodin ameliorates cisplatin-induced apoptosis of rat renal tubular cells in vitro through modulating the AMPK/mTOR signaling pathways and activating autophagy. Emodin may have therapeutic potential for the prevention of cisplatin-induced nephrotoxicity. PMID:26775661

Emodin ameliorates cisplatin-induced apoptosis of rat renal tubular cells in vitro by activating autophagy.

PubMed

Liu, Hong; Gu, Liu-bao; Tu, Yue; Hu, Hao; Huang, Yan-ru; Sun, Wei

2016-02-01

A previous report shows that emodin extracted from the Chinese herbs rhubarb and giant knotweed rhizome can ameliorate the anticancer drug cisplatin-induced injury of HEK293 cells. In this study, we investigated whether and how emodin could protect renal tubular epithelial cells against cisplatin-induced nephrotoxicity in vitro. The viability and apoptosis of normal rat renal tubular epithelial cells (NRK-52E) were detected using formazan assay and flow cytometry analysis, respectively. The expression levels of cleaved caspase-3, autophagy maker LC3 I/II, and AMPK/mTOR signaling pathway-related proteins were measured with Western blot analysis. The changes of morphology and RFP-LC3 fluorescence were observed under microscopy. Cisplatin (10-50 μmol/L) dose-dependently induced cell damage and apoptosis in NRK-52E cells, whereas emodin (10 and 100 μmol/L) significantly ameliorated cisplatin-induced cell damage, apoptosis and caspase-3 cleavage. Emodin dose-dependently increased LC3-II levels and induced RFP-LC3-containing punctate structures in NRK-52E cells. Furthermore, the protective effects of emodin were abolished by bafilomycin A1 (10 nmol/L), and mimicked by rapamycin (100 nmol/L). Moreover, emodin increased the phosphorylation of AMPK and suppressed the phosphorylation of mTOR. The AMPK inhibitor compound C (10 μmol/L) not only abolished emodin-induced autophagy activation, but also emodin-induced anti-apoptotic effects. Emodin ameliorates cisplatin-induced apoptosis of rat renal tubular cells in vitro through modulating the AMPK/mTOR signaling pathways and activating autophagy. Emodin may have therapeutic potential for the prevention of cisplatin-induced nephrotoxicity.

Role of Nitric Oxide in the Regulation of Renin and Vasopressin Secretion

NASA Technical Reports Server (NTRS)

Reid, Ian A.

1994-01-01

Research during recent years has established nitric oxide as a unique signaling molecule that plays important roles in the regulation of the cardiovascular, nervous, immune, and other systems. Nitric oxide has also been implicated in the control of the secretion of hormones by the pancreas, hypothalamus, and anterior pituitary gland, and evidence is accumulating that it contributes to the regulation of the secretion of renin and vasopressin, hormones that play key roles in the control of sodium and water balance. Several lines of evidence have implicated nitric oxide in the control of renin secretion. The enzyme nitric oxide synthase is present in vascular and tubular elements of the kidney, particularly in cells of the macula densa, a structure that plays an important role in the control of renin secretion. Guanylyl cyclase, a major target for nitric oxide, is also present in the kidney. Drugs that inhibit nitric oxide synthesis generally suppress renin release in vivo and in vitro, suggesting a stimulatory role for the L-arginine/nitric oxide pathway in the control of renin secretion. Under some conditions, however, blockade of nitric oxide synthesis increases renin secretion. Recent studies indicate that nitric oxide not only contributes to the regulation of basal renin secretion, but also participates in the renin secretory responses to activation of the renal baroreceptor, macula densa, and beta adrenoceptor mechanisms that regulate renin secretion. Histochemical and immunocytochemical studies have revealed the presence of nitric oxide synthase in the supraoptic and paraventricular nuclei of the hypothalamus and in the posterior pituitary gland. Colocalization of nitric oxide synthase and vasopressin has been demonstrated in some hypothalamic neurons. Nitric oxide synthase activity in the hypothalamus and pituitary is increased by maneuvers known to stimulate vasopressin secretion, including salt loading and dehydration, Administration of L-arginine and nitric

78 FR 14361 - U.S. Steel Tubular Products, Inc., Mckeesport Tubular Operations Division, Subsidiary of United...

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High glucose augments angiotensinogen in human renal proximal tubular cells through hepatocyte nuclear factor-5

PubMed Central

Wang, Juan; Shibayama, Yuki; Kobori, Hiroyuki; Liu, Ya; Kobara, Hideki; Masaki, Tsutomu; Wang, Zhiyu

2017-01-01

High glucose has been demonstrated to induce angiotensinogen (AGT) synthesis in the renal proximal tubular cells (RPTCs) of rats, which may further activate the intrarenal renin-angiotensin system (RAS) and contribute to diabetic nephropathy. This study aimed to investigate the effects of high glucose on AGT in the RPTCs of human origin and identify the glucose-responsive transcriptional factor(s) that bind(s) to the DNA sequences of AGT promoter in human RPTCs. Human kidney (HK)-2 cells were treated with normal glucose (5.5 mM) and high glucose (15.0 mM), respectively. Levels of AGT mRNA and AGT secretion of HK-2 cells were measured by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Consecutive 5’-end deletion mutant constructs and different site-directed mutagenesis products of human AGT promoter sequences were respectively transfected into HK-2 cells, followed by AGT promoter activity measurement through dual luciferase assay. High glucose significantly augmented the levels of AGT mRNA and AGT secretion of HK-2 cells, compared with normal glucose treatment. High glucose also significantly augmented AGT promoter activity in HK-2 cells transfected with the constructs of human AGT promoter sequences, compared with normal glucose treatment. Hepatocyte nuclear factor (HNF)-5 was found to be one of the glucose-responsive transcriptional factors of AGT in human RPTCs, since the mutation of its binding sites within AGT promoter sequences abolished the above effects of high glucose on AGT promoter activity as well as levels of AGT mRNA and its secretion. The present study has demonstrated, for the first time, that high glucose augments AGT in human RPTCs through HNF-5, which provides a potential therapeutic target for diabetic nephropathy. PMID:29053707

Inner Surface Chirality of Single-Handed Twisted Carbonaceous Tubular Nanoribbons.

PubMed

Liu, Dan; Li, Baozong; Guo, Yongmin; Li, Yi; Yang, Yonggang

2015-11-01

Single-handed twisted 4,4'-biphenylene-bridged polybissilsesquioxane tubular nanoribbons and single-layered nanoribbons were prepared by tuning the water/ethanol volume ratio in the reaction mixture at pH = 11.6 through a supramolecular templating approach. The single-layered nanoribbons were formed by shrinking tubular nanoribbons after the removal of the templates. In addition, solvent-induced handedness inversion was achieved. The handedness of the polybissilsesquioxanes could be controlled by changing the ethanol/water volume ratio in the reaction mixture. After carbonization at 900 °C for 4.0 h and removal of silica, single-handed twisted carbonaceous tubular nanoribbons and single-layered nanoribbons with micropores in the walls were obtained. X-ray diffraction and Raman spectroscopy analyses indicated that the carbon is predominantly amorphous. The circular dichroism spectra show that the twisted tubular nanoribbons exhibit optical activity, while the twisted single-layered nanoribbons do not. The results shown here indicate that chirality is transferred from the organic self-assemblies to the inner surfaces of the 4,4'-biphenylene-bridged polybissilsesquioxane tubular nanoribbons and subsequently to those of the carbonaceous tubular nanoribbons. © 2015 Wiley Periodicals, Inc.

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Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-21

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Renal tubular ACE-mediated tubular injury is the major contributor to microalbuminuria in early diabetic nephropathy.

PubMed

Eriguchi, Masahiro; Lin, Mercury; Yamashita, Michifumi; Zhao, Tuantuan V; Khan, Zakir; Bernstein, Ellen A; Gurley, Susan B; Gonzalez-Villalobos, Romer A; Bernstein, Kenneth E; Giani, Jorge F

2018-04-01

Diabetic nephropathy is a major cause of end-stage renal disease in developed countries. While angiotensin-converting enzyme (ACE) inhibitors are used to treat diabetic nephropathy, how intrarenal ACE contributes to diabetic renal injury is uncertain. Here, two mouse models with different patterns of renal ACE expression were studied to determine the specific contribution of tubular vs. glomerular ACE to early diabetic nephropathy: it-ACE mice, which make endothelial ACE but lack ACE expression by renal tubular epithelium, and ACE 3/9 mice, which lack endothelial ACE and only express renal ACE in tubular epithelial cells. The absence of endothelial ACE normalized the glomerular filtration rate and endothelial injury in diabetic ACE 3/9 mice. However, these mice developed tubular injury and albuminuria and displayed low renal levels of megalin that were similar to those observed in diabetic wild-type mice. In diabetic it-ACE mice, despite hyperfiltration, the absence of renal tubular ACE greatly reduced tubulointerstitial injury and albuminuria and increased renal megalin expression compared with diabetic wild-type and diabetic ACE 3/9 mice. These findings demonstrate that endothelial ACE is a central regulator of the glomerular filtration rate while tubular ACE is a key player in the development of tubular injury and albuminuria. These data suggest that tubular injury, rather than hyperfiltration, is the main cause of microalbuminuria in early diabetic nephropathy.

Secretion of Ipa proteins by Shigella flexneri: inducer molecules and kinetics of activation.

PubMed Central

Bahrani, F K; Sansonetti, P J; Parsot, C

1997-01-01

The type III Mxi-Spa secretion machinery of Shigella flexneri is responsible for secretion of Ipa proteins, which are involved in the entry of bacteria into epithelial cells. Ipa proteins accumulate within bacteria growing in laboratory media, and their secretion is activated upon contact of bacteria with eukaryotic cells. In this study, we have identified a group of chemical compounds, including Congo red, Evans blue, and direct orange, which are able to induce secretion of Ipa proteins by bacteria suspended in phosphate-buffered saline. Parameters of kinetics of activation of Ipa secretion by Congo red were determined by measuring by enzyme-linked immunosorbent assay the amount of IpaC secreted and by investigating the increase in susceptibility of Ipa proteins to proteinase K degradation. Ipa secretion occurred at 37 degrees C, was obtained with 5 to 10 microM Congo red, and was complete within 30 min. In addition, activation of Ipa secretion by Congo red was observed with bacteria harvested throughout the exponential phase of growth but not with bacteria in the stationary phase. The interactions of Congo red and Congo red-related compounds with the Mxi-Spa secretion apparatus might be specific hydrophobic interactions similar to those involved in binding of Congo red to amyloid proteins. PMID:9316999

Evidence for net renal tubule oxalate secretion in patients with calcium kidney stones

PubMed Central

Zisman, Anna L.; Asplin, John R.; Worcester, Elaine M.; Coe, Fredric L.

2011-01-01

Little is known about the renal handling of oxalate in patients with idiopathic hypercalciuria (IH). To explore the role of tubular oxalate handling in IH and to evaluate whether differences exist between IH and normal controls, we studied 19 IH subjects, 8 normal subjects, and 2 bariatric stone formers (BSF) during a 1-day General Clinical Research Center protocol utilizing a low-oxalate diet. Urine and blood samples were collected at 30- to 60-min intervals while subjects were fasting and after they ate three meals providing known amounts of calcium, phosphorus, sodium, protein, oxalate, and calories. Plasma oxalate concentrations and oxalate-filtered loads were similar between patients (includes IH and BSF) and controls in both the fasting and fed states. Urinary oxalate excretion was significantly higher in patients vs. controls regardless of feeding state. Fractional excretion of oxalate (FEOx) was >1, suggesting tubular secretion of oxalate, in 6 of 19 IH and both BSF, compared with none of the controls (P < 0.00001). Adjusted for water extraction along the nephron, urine oxalate rose more rapidly among patients than normal subjects with increases in plasma oxalate. Our findings identify tubular secretion of oxalate as a key mediator of hyperoxaluria in calcium stone formers, potentially as a means of maintaining plasma oxalate in a tight range. PMID:21123489

Tubular nanostructured materials for bioapplications

NASA Astrophysics Data System (ADS)

Xie, Jining; Chen, Linfeng; Srivatsan, Malathi; Varadan, Vijay K.

2009-03-01

Tubular nanomaterials possess hollow structures as well as high aspect ratios. In addition to their unique physical and chemical properties induced by their nanoscale dimensions, their inner voids and outer surfaces make them ideal candidates for a number of biomedical applications. In this work, three types of tubular nanomaterials including carbon nanotubes, hematite nanotubes, and maghemite nanotubes, were synthesized by different chemical techniques. Their structural and crystalline properties were characterized. For potential bioapplications of tubular nanomaterials, experimental investigations were carried out to demonstrate the feasibility of using carbon nanotubes, hematite nanotubes, and maghemite nanotubes in glucose sensing, neuronal growth, and drug delivery, respectively. Preliminary results show the promise of tubular nanomaterials in future biomedical applications.

Tubular Unimolecular Transmembrane Channels: Construction Strategy and Transport Activities.

PubMed

Si, Wen; Xin, Pengyang; Li, Zhan-Ting; Hou, Jun-Li

2015-06-16

Lipid bilayer membranes separate living cells from their environment. Membrane proteins are responsible for the processing of ion and molecular inputs and exports, sensing stimuli and signals across the bilayers, which may operate in a channel or carrier mechanism. Inspired by these wide-ranging functions of membrane proteins, chemists have made great efforts in constructing synthetic mimics in order to understand the transport mechanisms, create materials for separation, and develop therapeutic agents. Since the report of an alkylated cyclodextrin for transporting Cu(2+) and Co(2+) by Tabushi and co-workers in 1982, chemists have constructed a variety of artificial transmembrane channels by making use of either the multimolecular self-assembly or unimolecular strategy. In the context of the design of unimolecular channels, important advances have been made, including, among others, the tethering of natural gramicidin A or alamethicin and the modification of various macrocycles such as crown ethers, cyclodextrins, calixarenes, and cucurbiturils. Many of these unimolecular channels exhibit high transport ability for metal ions, particularly K(+) and Na(+). Concerning the development of artificial channels based on macrocyclic frameworks, one straightforward and efficient approach is to introduce discrete chains to reinforce their capability to insert into bilayers. Currently, this approach has found the widest applications in the systems of crown ethers and calixarenes. We envisioned that for macrocycle-based unimolecular channels, control of the arrangement of the appended chains in the upward and/or downward direction would favor the insertion of the molecular systems into bilayers, while the introduction of additional interactions among the chains would further stabilize a tubular conformation. Both factors should be helpful for the formation of new efficient channels. In this Account, we discuss our efforts in designing new unimolecular artificial channels from

Tubular inverse opal scaffolds for biomimetic vessels

NASA Astrophysics Data System (ADS)

Zhao, Ze; Wang, Jie; Lu, Jie; Yu, Yunru; Fu, Fanfan; Wang, Huan; Liu, Yuxiao; Zhao, Yuanjin; Gu, Zhongze

2016-07-01

There is a clinical need for tissue-engineered blood vessels that can be used to replace or bypass damaged arteries. The success of such grafts depends strongly on their ability to mimic native arteries; however, currently available artificial vessels are restricted by their complex processing, controversial integrity, or uncontrollable cell location and orientation. Here, we present new tubular scaffolds with specific surface microstructures for structural vessel mimicry. The tubular scaffolds are fabricated by rotationally expanding three-dimensional tubular inverse opals that are replicated from colloidal crystal templates in capillaries. Because of the ordered porous structure of the inverse opals, the expanded tubular scaffolds are imparted with circumferentially oriented elliptical pattern microstructures on their surfaces. It is demonstrated that these tailored tubular scaffolds can effectively make endothelial cells to form an integrated hollow tubular structure on their inner surface and induce smooth muscle cells to form a circumferential orientation on their outer surface. These features of our tubular scaffolds make them highly promising for the construction of biomimetic blood vessels.There is a clinical need for tissue-engineered blood vessels that can be used to replace or bypass damaged arteries. The success of such grafts depends strongly on their ability to mimic native arteries; however, currently available artificial vessels are restricted by their complex processing, controversial integrity, or uncontrollable cell location and orientation. Here, we present new tubular scaffolds with specific surface microstructures for structural vessel mimicry. The tubular scaffolds are fabricated by rotationally expanding three-dimensional tubular inverse opals that are replicated from colloidal crystal templates in capillaries. Because of the ordered porous structure of the inverse opals, the expanded tubular scaffolds are imparted with circumferentially

Tubular Recovery after Acute Kidney Injury.

PubMed

Fattah, Hadi; Vallon, Volker

2018-05-31

A significant portion of patients who are affected by acute kidney injury (AKI) do not fully recover due to largely unclear reasons. Restoration of tubular function has been proposed to be a prerequisite for glomerular filtration rate (GFR) recovery. Proximal tubular cells dedifferentiate during the tubular injury phase, which is required for subsequent cell proliferation and replacement of lost epithelial cells. Experimental studies indicate that some cells fail to redifferentiate and continue to produce growth factors (e.g., transforming growth factor β) that can induce fibrosis. Preclinical studies provide first evidence for beneficial effects of inhibiting glucose transport in the proximal tubule in models of ischemia-reperfusion injury. Comparing renal RNA sequencing data with kidney function during recovery from varying levels of AKI may provide new cues with regard to the sequence of events and help identify key determinants of recovery from AKI. Key Messages: Tubular recovery after AKI is vital for recovery of kidney function including improvement of GFR, and likely determines which patients fully recover from AKI or progress to chronic kidney disease. There is a need to better understand the sequence of events and the processes of tubular cell proliferation and repair, including safe strategies to intervene. The temporary inhibition of selected tubular transport processes, possibly in selected nephron regions, may provide an opportunity to improve tubular cell energetics and facilitate tubular cell recovery with consequences for kidney outcome. © 2018 S. Karger AG, Basel.

Elevated oxidized glutathione in cystinotic proximal tubular epithelial cells.

PubMed

Wilmer, Martijn J G; de Graaf-Hess, Adriana; Blom, Henk J; Dijkman, Henry B P M; Monnens, Leo A; van den Heuvel, Lambertus P; Levtchenko, Elena N

2005-11-18

Cystinosis, the most frequent cause of inborn Fanconi syndrome, is characterized by the lysosomal cystine accumulation, caused by mutations in the CTNS gene. To elucidate the pathogenesis of cystinosis, we cultured proximal tubular cells from urine of cystinotic patients (n = 9) and healthy controls (n = 9), followed by immortalization with human papilloma virus (HPV E6/E7). Obtained cell lines displayed basolateral polarization, alkaline phosphatase activity, and presence of aminopeptidase N (CD-13) and megalin, confirming their proximal tubular origin. Cystinotic cell lines exhibited elevated cystine levels (0.86 +/- 0.95 nmol/mg versus 0.09 +/- 0.01 nmol/mg protein in controls, p = 0.03). Oxidized glutathione was elevated in cystinotic cells (1.16 +/- 0.83 nmol/mg versus 0.29 +/- 0.18 nmol/mg protein, p = 0.04), while total glutathione, free cysteine, and ATP contents were normal in these cells. In conclusion, elevated oxidized glutathione in cystinotic proximal tubular epithelial cell lines suggests increased oxidative stress, which may contribute to tubular dysfunction in cystinosis.

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2012-06-08

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Effect of OPC-12759 on EGF receptor activation, p44/p42 MAPK activity, and secretion in conjunctival goblet cells.

PubMed

Ríos, J David; Shatos, Marie A; Urashima, Hiroki; Dartt, Darlene A

2008-04-01

The purpose of the study was to determine if OPC-12759 stimulates secretion from conjunctival goblet cells in culture and if it activates the EGF receptor (EGFR) and p44/p42 mitogen-activated protein kinase (MAPK) to cause mucin secretion. Conjunctival goblet cells were cultured from pieces of male rat conjunctiva. OPC-12759 was added at increasing concentrations and for varying times to the cultured cells. The cholinergic agonist carbachol was used as a positive control. In selected experiments an inhibitor of the EGFR, AG1478, or an inhibitor of the kinase that activates MAPK, U0126, were added before OPC-12759. Goblet cell secretion of high molecular weight glycoconjugates was measured by an enzyme-linked lectin assay using the lectin UEA-1. Activation of the EGFR and MAPK were determined with Western blotting analysis using antibodies specific to the phosphorylated and the total amounts of these proteins. We found that OPC-12759 induced goblet cell secretion in a time- and concentration-dependent manner. Inhibition of the EGFR with AG1478 blocked secretion stimulated by OPC-12759. Inhibition of MAPK with U0126 also blocked secretion stimulated by OPC-12759. OPC-12759 increased the phosphorylation of the EGFR and MAPK in a time-dependent manner. We concluded that OPC-12759 stimulates secretion from cultured conjunctival goblet cells by activating the EGFR, which then induces MAPK activity.

Closing Ranks: The Secret of Army Active and Reserve Component Harmony

DTIC Science & Technology

1992-02-11

FUNDING NUMBERS PROGRAM I PROJECT TASK IWORK UNIT ELEMENT NO. NO. NO. [ACCESSION NO 11. TITLE (include Security Classification) Closing Ranks: The Secret of...and recently served on the DOD Total Force Policy Study Group Staff, Washington, DC. iv CLOSING RANKS: THE SECRET OF ARMY ACTIVE AND RESERVE COMPONENT...same old rebuff by the AC senior leadership. If we accept the premise that attitudes and perceptions are the secrets to AC/RC harmony, then the real

Tubular inverse opal scaffolds for biomimetic vessels.

PubMed

Zhao, Ze; Wang, Jie; Lu, Jie; Yu, Yunru; Fu, Fanfan; Wang, Huan; Liu, Yuxiao; Zhao, Yuanjin; Gu, Zhongze

2016-07-14

There is a clinical need for tissue-engineered blood vessels that can be used to replace or bypass damaged arteries. The success of such grafts depends strongly on their ability to mimic native arteries; however, currently available artificial vessels are restricted by their complex processing, controversial integrity, or uncontrollable cell location and orientation. Here, we present new tubular scaffolds with specific surface microstructures for structural vessel mimicry. The tubular scaffolds are fabricated by rotationally expanding three-dimensional tubular inverse opals that are replicated from colloidal crystal templates in capillaries. Because of the ordered porous structure of the inverse opals, the expanded tubular scaffolds are imparted with circumferentially oriented elliptical pattern microstructures on their surfaces. It is demonstrated that these tailored tubular scaffolds can effectively make endothelial cells to form an integrated hollow tubular structure on their inner surface and induce smooth muscle cells to form a circumferential orientation on their outer surface. These features of our tubular scaffolds make them highly promising for the construction of biomimetic blood vessels.

Neuronal Activity Promotes Glioma Growth through Neuroligin-3 Secretion.

PubMed

Venkatesh, Humsa S; Johung, Tessa B; Caretti, Viola; Noll, Alyssa; Tang, Yujie; Nagaraja, Surya; Gibson, Erin M; Mount, Christopher W; Polepalli, Jai; Mitra, Siddhartha S; Woo, Pamelyn J; Malenka, Robert C; Vogel, Hannes; Bredel, Markus; Mallick, Parag; Monje, Michelle

2015-05-07

Active neurons exert a mitogenic effect on normal neural precursor and oligodendroglial precursor cells, the putative cellular origins of high-grade glioma (HGG). By using optogenetic control of cortical neuronal activity in a patient-derived pediatric glioblastoma xenograft model, we demonstrate that active neurons similarly promote HGG proliferation and growth in vivo. Conditioned medium from optogenetically stimulated cortical slices promoted proliferation of pediatric and adult patient-derived HGG cultures, indicating secretion of activity-regulated mitogen(s). The synaptic protein neuroligin-3 (NLGN3) was identified as the leading candidate mitogen, and soluble NLGN3 was sufficient and necessary to promote robust HGG cell proliferation. NLGN3 induced PI3K-mTOR pathway activity and feedforward expression of NLGN3 in glioma cells. NLGN3 expression levels in human HGG negatively correlated with patient overall survival. These findings indicate the important role of active neurons in the brain tumor microenvironment and identify secreted NLGN3 as an unexpected mechanism promoting neuronal activity-regulated cancer growth. Copyright © 2015 Elsevier Inc. All rights reserved.

Methods of increasing secretion of polypeptides having biological activity

DOEpatents

Merino, Sandra

2014-05-27

The present invention relates to methods for producing a secreted polypeptide having biological activity, comprising: (a) transforming a fungal host cell with a fusion protein construct encoding a fusion protein, which comprises: (i) a first polynucleotide encoding a signal peptide; (ii) a second polynucleotide encoding at least a catalytic domain of an endoglucanase or a portion thereof; and (iii) a third polynucleotide encoding at least a catalytic domain of a polypeptide having biological activity; wherein the signal peptide and at least the catalytic domain of the endoglucanase increases secretion of the polypeptide having biological activity compared to the absence of at least the catalytic domain of the endoglucanase; (b) cultivating the transformed fungal host cell under conditions suitable for production of the fusion protein; and (c) recovering the fusion protein, a component thereof, or a combination thereof, having biological activity, from the cultivation medium.

Methods of increasing secretion of polypeptides having biological activity

DOEpatents

Merino, Sandra

2014-10-28

The present invention relates to methods for producing a secreted polypeptide having biological activity, comprising: (a) transforming a fungal host cell with a fusion protein construct encoding a fusion protein, which comprises: (i) a first polynucleotide encoding a signal peptide; (ii) a second polynucleotide encoding at least a catalytic domain of an endoglucanase or a portion thereof; and (iii) a third polynucleotide encoding at least a catalytic domain of a polypeptide having biological activity; wherein the signal peptide and at least the catalytic domain of the endoglucanase increases secretion of the polypeptide having biological activity compared to the absence of at least the catalytic domain of the endoglucanase; (b) cultivating the transformed fungal host cell under conditions suitable for production of the fusion protein; and (c) recovering the fusion protein, a component thereof, or a combination thereof, having biological activity, from the cultivation medium.

Methods of increasing secretion of polypeptides having biological activity

DOEpatents

Merino, Sandra

2015-04-14

The present invention relates to methods for producing a secreted polypeptide having biological activity, comprising: (a) transforming a fungal host cell with a fusion protein construct encoding a fusion protein, which comprises: (i) a first polynucleotide encoding a signal peptide; (ii) a second polynucleotide encoding at least a catalytic domain of an endoglucanase or a portion thereof; and (iii) a third polynucleotide encoding at least a catalytic domain of a polypeptide having biological activity; wherein the signal peptide and at least the catalytic domain of the endoglucanase increases secretion of the polypeptide having biological activity compared to the absence of at least the catalytic domain of the endoglucanase; (b) cultivating the transformed fungal host cell under conditions suitable for production of the fusion protein; and (c) recovering the fusion protein, a component thereof, or a combination thereof, having biological activity, from the cultivation medium.

Methods of increasing secretion of polypeptides having biological activity

DOEpatents

Merino, Sandra

2013-10-01

The present invention relates to methods for producing a secreted polypeptide having biological activity, comprising: (a) transforming a fungal host cell with a fusion protein construct encoding a fusion protein, which comprises: (i) a first polynucleotide encoding a signal peptide; (ii) a second polynucleotide encoding at least a catalytic domain of an endoglucanase or a portion thereof; and (iii) a third polynucleotide encoding at least a catalytic domain of a polypeptide having biological activity; wherein the signal peptide and at least the catalytic domain of the endoglucanase increases secretion of the polypeptide having biological activity compared to the absence of at least the catalytic domain of the endoglucanase; (b) cultivating the transformed fungal host cell under conditions suitable for production of the fusion protein; and (c) recovering the fusion protein, a component thereof, or a combination thereof, having biological activity, from the cultivation medium.

Hemodynamic and tubular changes induced by contrast media.

PubMed

Caiazza, Antonella; Russo, Luigi; Sabbatini, Massimo; Russo, Domenico

2014-01-01

The incidence of acute kidney injury induced by contrast media (CI-AKI) is the third cause of AKI in hospitalized patients. Contrast media cause relevant alterations both in renal hemodynamics and in renal tubular cell function that lead to CI-AKI. The vasoconstriction of intrarenal vasculature is the main hemodynamic change induced by contrast media; the vasoconstriction is accompanied by a cascade of events leading to ischemia and reduction of glomerular filtration rate. Cytotoxicity of contrast media causes apoptosis of tubular cells with consequent formation of casts and worsening of ischemia. There is an interplay between the negative effects of contrast media on renal hemodynamics and on tubular cell function that leads to activation of renin-angiotensin system and increased production of reactive oxygen species (ROS) within the kidney. Production of ROS intensifies cellular hypoxia through endothelial dysfunction and alteration of mechanisms regulating tubular cells transport. The physiochemical characteristics of contrast media play a critical role in the incidence of CI-AKI. Guidelines suggest the use of either isoosmolar or low-osmolar contrast media rather than high-osmolar contrast media particularly in patients at increased risk of CI-AKI. Older age, presence of atherosclerosis, congestive heart failure, chronic renal disease, nephrotoxic drugs, and diuretics may multiply the risk of CI-AKI.

Hemodynamic and Tubular Changes Induced by Contrast Media

PubMed Central

Caiazza, Antonella; Russo, Luigi; Russo, Domenico

2014-01-01

The incidence of acute kidney injury induced by contrast media (CI-AKI) is the third cause of AKI in hospitalized patients. Contrast media cause relevant alterations both in renal hemodynamics and in renal tubular cell function that lead to CI-AKI. The vasoconstriction of intrarenal vasculature is the main hemodynamic change induced by contrast media; the vasoconstriction is accompanied by a cascade of events leading to ischemia and reduction of glomerular filtration rate. Cytotoxicity of contrast media causes apoptosis of tubular cells with consequent formation of casts and worsening of ischemia. There is an interplay between the negative effects of contrast media on renal hemodynamics and on tubular cell function that leads to activation of renin-angiotensin system and increased production of reactive oxygen species (ROS) within the kidney. Production of ROS intensifies cellular hypoxia through endothelial dysfunction and alteration of mechanisms regulating tubular cells transport. The physiochemical characteristics of contrast media play a critical role in the incidence of CI-AKI. Guidelines suggest the use of either isoosmolar or low-osmolar contrast media rather than high-osmolar contrast media particularly in patients at increased risk of CI-AKI. Older age, presence of atherosclerosis, congestive heart failure, chronic renal disease, nephrotoxic drugs, and diuretics may multiply the risk of CI-AKI. PMID:24678510

Polyphenol-Stabilized Tubular Elastin Scaffolds for Tissue Engineered Vascular Grafts

PubMed Central

Chuang, Ting-Hsien; Stabler, Christopher; Simionescu, Agneta

2009-01-01

Tissue-engineered vascular grafts require elastic, acellular porous scaffolds with controlled biodegradability and properties matching those of natural arteries. Elastin would be a desirable component for such applications, but elastin does not easily regenerate experimentally. Our approach is to develop tubular elastin scaffolds using decellularization and removal of collagen from porcine carotid arteries (∼5 mm diameter) using alkaline extraction. Because elastin is susceptible to rapid degeneration after implantation, scaffolds were further treated with penta-galloyl glucose (PGG), an established polyphenolic elastin-stabilizing agent. Scaffolds were compared in vitro with detergent-decellularized arteries for structure, composition, resistance to degradation, mechanical properties, and cytotoxicity and in vivo for cell infiltration and remodeling potential. Results showed effective decellularization and almost complete collagen removal by alkaline extraction. PGG-treated elastin scaffolds proved to be resistant to elastase digestion in vitro, maintained their cylindrical shapes, showed high resistance to burst pressures, and supported growth of endothelial cells and fibroblasts. In vivo results showed that PGG treatment reduced the rate of elastin biodegradation and controlled cell infiltration but did not hamper new collagen and proteoglycan deposition and secretion of matrix-degrading proteases. Alkali-purified, PGG-treated tubular arterial elastin scaffolds exhibit many desirable properties to be recommended for clinical applications as vascular grafts. PMID:19254115

Tubular and Spherical SiO₂ Obtained by Sol Gel Method for Lipase Immobilization and Enzymatic Activity.

PubMed

Anastasescu, Crina; Preda, Silviu; Rusu, Adriana; Culita, Dana; Plavan, Gabriel; Strungaru, Stefan; Calderon-Moreno, Jose Maria; Munteanu, Cornel; Gifu, Catalina; Enache, Mirela; Socoteanu, Radu; Angelescu, Daniel; Anastasescu, Mihai; Gartner, Mariuca; Balint, Ioan; Zaharescu, Maria

2018-06-05

A wide range of hybrid biomaterials has been designed in order to sustain bioremediation processes by associating sol-gel SiO₂ matrices with various biologically active compounds (enzymes, antibodies). SiO₂ is a widespread, chemically stable and non-toxic material; thus, the immobilization of enzymes on silica may lead to improving the efficiency of biocatalysts in terms of endurance and economic costs. Our present work explores the potential of different hybrid morphologies, based on hollow tubes and solid spheres of amorphous SiO₂, for enzyme immobilization and the development of competitive biocatalysts. The synthesis protocol and structural characterization of spherical and tubular SiO₂ obtained by the sol gel method were fully investigated in connection with the subsequent immobilization of lipase from Rhizopus orizae . The immobilization is conducted at pH 6, lower than the isoelectric point of lipase and higher than the isoelectric point of silica, which is meant to sustain the physical interactions of the enzyme with the SiO₂ matrix. The morphological, textural and surface properties of spherical and tubular SiO₂ were investigated by SEM, nitrogen sorption, and electrokinetic potential measurements, while the formation and characterization of hybrid organic-inorganic complexes were studied by UV-VIS, FTIR-ATR and fluorescence spectroscopy. The highest degree of enzyme immobilization (as depicted from total organic carbon) was achieved for tubular morphology and the hydrolysis of p-nitrophenyl acetate was used as an enzymatic model reaction conducted in the presence of hybrid lipase⁻SiO₂ complex.

Lovastatin prevents cisplatin-induced activation of pro-apoptotic DNA damage response (DDR) of renal tubular epithelial cells

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

Krüger, Katharina; Ziegler, Verena; Hartmann, Christina

The platinating agent cisplatin (CisPt) is commonly used in the therapy of various types of solid tumors. The anticancer efficacy of CisPt largely depends on the formation of bivalent DNA intrastrand crosslinks, which stimulate mechanisms of the DNA damage response (DDR), thereby triggering checkpoint activation, gene expression and cell death. The clinically most relevant adverse effect associated with CisPt treatment is nephrotoxicity that results from damage to renal tubular epithelial cells. Here, we addressed the question whether the HMG-CoA-reductase inhibitor lovastatin affects the DDR of renal cells by employing rat renal proximal tubular epithelial (NRK-52E) cells as in vitro model.more » The data show that lovastatin has extensive inhibitory effects on CisPt-stimulated DDR of NRK-52E cells as reflected on the levels of phosphorylated ATM, Chk1, Chk2, p53 and Kap1. Mitigation of CisPt-induced DDR by lovastatin was independent of the formation of DNA damage as demonstrated by (i) the analysis of Pt-(GpG) intrastrand crosslink formation by Southwestern blot analyses and (ii) the generation of DNA strand breaks as analyzed on the level of nuclear γH2AX foci and employing the alkaline comet assay. Lovastatin protected NRK-52E cells from the cytotoxicity of high CisPt doses as shown by measuring cell viability, cellular impedance and flow cytometry-based analyses of cell death. Importantly, the statin also reduced the level of kidney DNA damage and apoptosis triggered by CisPt treatment of mice. The data show that the lipid-lowering drug lovastatin extensively counteracts pro-apoptotic signal mechanisms of the DDR of tubular epithelial cells following CisPt injury. - Highlights: • Lovastatin blocks ATM/ATR-regulated DDR of tubular cells following CisPt treatment. • Lovastatin attenuates CisPt-induced activation of protein kinase ATM in vitro. • Statin-mediated DDR inhibition is independent of initial DNA damage formation. • Statin-mediated blockage

Nano-tubular cellulose for bioprocess technology development.

PubMed

Koutinas, Athanasios A; Sypsas, Vasilios; Kandylis, Panagiotis; Michelis, Andreas; Bekatorou, Argyro; Kourkoutas, Yiannis; Kordulis, Christos; Lycourghiotis, Alexis; Banat, Ibrahim M; Nigam, Poonam; Marchant, Roger; Giannouli, Myrsini; Yianoulis, Panagiotis

2012-01-01

Delignified cellulosic material has shown a significant promotional effect on the alcoholic fermentation as yeast immobilization support. However, its potential for further biotechnological development is unexploited. This study reports the characterization of this tubular/porous cellulosic material, which was done by SEM, porosimetry and X-ray powder diffractometry. The results showed that the structure of nano-tubular cellulose (NC) justifies its suitability for use in "cold pasteurization" processes and its promoting activity in bioprocessing (fermentation). The last was explained by a glucose pump theory. Also, it was demonstrated that crystallization of viscous invert sugar solutions during freeze drying could not be otherwise achieved unless NC was present. This effect as well as the feasibility of extremely low temperature fermentation are due to reduction of the activation energy, and have facilitated the development of technologies such as wine fermentations at home scale (in a domestic refrigerator). Moreover, NC may lead to new perspectives in research such as the development of new composites, templates for cylindrical nano-particles, etc.

Activated renal tubular Wnt/β-catenin signaling triggers renal inflammation during overload proteinuria.

PubMed

Wong, Dickson W L; Yiu, Wai Han; Chan, Kam Wa; Li, Ye; Li, Bin; Lok, Sarah W Y; Taketo, Makoto M; Igarashi, Peter; Chan, Loretta Y Y; Leung, Joseph C K; Lai, Kar Neng; Tang, Sydney C W

2018-06-01

Imbalance of Wnt/β-catenin signaling in renal cells is associated with renal dysfunction, yet the precise mechanism is poorly understood. Previously we observed activated Wnt/β-catenin signaling in renal tubules during proteinuric nephropathy with an unknown net effect. Therefore, to identify the definitive role of tubular Wnt/β-catenin, we generated a novel transgenic "Tubcat" mouse conditionally expressing stabilized β-catenin specifically in renal tubules following tamoxifen administration. Four weeks after tamoxifen injection, uninephrectomized Tubcat mice displayed proteinuria and elevated blood urea nitrogen levels compared to non-transgenic mice, implying a detrimental effect of the activated signaling. This was associated with infiltration of the tubulointerstitium predominantly by M1 macrophages and overexpression of the inflammatory chemocytokines CCL-2 and RANTES. Induction of overload proteinuria by intraperitoneal injection of low-endotoxin bovine serum albumin following uninephrectomy for four weeks aggravated proteinuria and increased blood urea nitrogen levels to a significantly greater extent in Tubcat mice. Renal dysfunction correlated with the degree of M1 macrophage infiltration in the tubulointerstitium and renal cortical up-regulation of CCL-2, IL-17A, IL-1β, CXCL1, and ICAM-1. There was overexpression of cortical TLR-4 and NLRP-3 in Tubcat mice, independent of bovine serum albumin injection. Finally, there was no fibrosis, activation of epithelial-mesenchymal transition or non-canonical Wnt pathways observed in the kidneys of Tubcat mice. Thus, conditional activation of renal tubular Wnt/β-catenin signaling in a novel transgenic mouse model demonstrates that this pathway enhances intrarenal inflammation via the TLR-4/NLRP-3 inflammasome axis in overload proteinuria. Copyright © 2018 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

Effects of autophagy and endocytosis on the activity of matrix metalloproteinase‑2 in human renal proximal tubular cells under hypoxia.

PubMed

Yu, Wenmin; Wang, Zhi; Li, Yiping; Liu, Lei; Liu, Jing; Ding, Fenggan; Zhang, Xiaoyi; Cheng, Zhengyuan; Chen, Pingsheng

2017-05-01

Tubulointerstitial fibrosis is characterized by tubular atrophy with basement membrane thickening and accumulation of interstitial extracellular matrix (ECM). A decrease in the activity of matrix metalloproteinase‑2 (MMP‑2) may promote this process. Although proximal tubular cells are sensitive to oxygen deprivation, whether cellular autophagy or endocytosis induced by hypoxia can alter the activity of MMP‑2 remains to be elucidated. The aim of the present study was to investigate whether autophagy and endocytosis induced by hypoxia can have an effect on the activity of MMP‑2 in HK‑2 cells. The investigations involved exposing the HK‑2 cell line to an autophagy inhibitor, 3‑MA, or an endocytotic inhibitor, filipin. The mRNA expression of MMP‑2 was elevated in the hypoxic milieu. Furthermore, it was found that filipin increased the activity of MMP‑2 under hypoxia. These results suggested that autophagy and endocytosis were potential mediators for the altered expression of MMP‑2, and endocytosis was a potential target for regulating the activity of MMP‑2. These data suggested that hypoxia may be an important pro‑fibrogenic stimulus, which acts in part via endocytosis.

Toxicological Significance of Renal Bcrp: Another Potential Transporter in the Elimination of Mercuric Ions from Proximal Tubular Cells

PubMed Central

Bridges, Christy C.; Zalups, Rudolfs K.; Joshee, Lucy

2015-01-01

Secretion of inorganic mercury (Hg2+) from proximal tubular cells into the tubular lumen has been shown to involve the multidrug resistance-associated protein 2 (Mrp2). Considering similarities in localization and substrate specificity between Mrp2 and the breast cancer resistance protein (Bcrp), we hypothesize that Bcrp may also play a role in the proximal tubular secretion of mercuric species. In order to test this hypothesis, the uptake of Hg2+ was examined initially using inside-out membrane vesicles containing Bcrp. The results of these studies suggest that Bcrp may be capable of transporting certain conjugates of Hg2+. To further characterize the role of Bcrp in the handling of mercuric ions and in the induction of Hg2+-induced nephropathy, Sprague-Dawley and Bcrp knockout (bcrp−/−) rats were exposed intravenously to a non-nephrotoxic (0.5 μmol • kg−1), a moderately nephrotoxic (1.5 μmol • kg−1) or a significantly nephrotoxic (2.0 μmol • kg−1) dose of HgCl2. In general, the accumulation of Hg2+ was greater in organs of bcrp−/− rats than in Sprague-Dawley rats, suggesting that Bcrp may play a role in the export of Hg2+ from target cells. Within the kidney, cellular injury and necrosis was more severe in bcrp−/− rats than in controls. The pattern of necrosis, which was localized in the inner cortex and the outer stripe of the outer medulla was significantly different from that observed in Mrp2-deficient animals. These findings suggest that Bcrp may be involved in the cellular export of select mercuric species and that its role in this export may differ from that of Mrp2. PMID:25868844

Suppression of hedgehog signaling regulates hepatic stellate cell activation and collagen secretion.

PubMed

Li, Tao; Leng, Xi-Sheng; Zhu, Ji-Ye; Wang, Gang

2015-01-01

Hepatic stellate cells (HSCs) play an important role in liver fibrosis. This study investigates the expression of hedgehog in HSC and the role of hedgehog signaling on activation and collagen secretion of HSC. Liver ex vivo perfusion with collagenase IV and density gradient centrifugation were used to isolate HSC. Expression of hedgehog signaling components Ihh, Smo, Ptc, Gli2 and Gli3 in HSC were detected by RT-PCR. Hedgehog siRNA vectors targeting Ihh, Smo and Gli2 were constructed and transfected into HSC respectively. Suppression of hedgehog signaling were detected by SYBR Green fluorescence quantitative RT-PCR. Effects of hedgehog signaling inhibition on HSC activation and collagen I secretion were analyzed. Hedgehog signaling components Ihh, Smo, Ptc, Gli2 and Gli3 were expressed in HSC. siRNA vectors targeting Ihh, Smo and Gli2 were successfully constructed and decreased target gene expression. Suppression of hedgehog signaling significantly decreased the expression of α-SMA in HSC (P<0.01). Collagen type I secretion of HSC were also significantly decreased (P<0.01). In summary, HSC activation and collagen secretion can be regulated by hedgehog signaling. Hedgehog may play a role in the pathogenesis of liver fibrosis.

Toxicological significance of renal Bcrp: Another potential transporter in the elimination of mercuric ions from proximal tubular cells

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

Bridges, Christy C., E-mail: bridges_cc@mercer.edu; Zalups, Rudolfs K.; Joshee, Lucy

Secretion of inorganic mercury (Hg{sup 2+}) from proximal tubular cells into the tubular lumen has been shown to involve the multidrug resistance-associated protein 2 (Mrp2). Considering similarities in localization and substrate specificity between Mrp2 and the breast cancer resistance protein (Bcrp), we hypothesize that Bcrp may also play a role in the proximal tubular secretion of mercuric species. In order to test this hypothesis, the uptake of Hg{sup 2+} was examined initially using inside-out membrane vesicles containing Bcrp. The results of these studies suggest that Bcrp may be capable of transporting certain conjugates of Hg{sup 2+}. To further characterize themore » role of Bcrp in the handling of mercuric ions and in the induction of Hg{sup 2+}-induced nephropathy, Sprague–Dawley and Bcrp knockout (bcrp{sup −/−}) rats were exposed intravenously to a non-nephrotoxic (0.5 μmol·kg{sup −1}), a moderately nephrotoxic (1.5 μmol·kg{sup −1}) or a significantly nephrotoxic (2.0 μmol·kg{sup −1}) dose of HgCl{sub 2}. In general, the accumulation of Hg{sup 2+} was greater in organs of bcrp{sup −/−} rats than in Sprague–Dawley rats, suggesting that Bcrp may play a role in the export of Hg{sup 2+} from target cells. Within the kidney, cellular injury and necrosis was more severe in bcrp{sup −/−} rats than in controls. The pattern of necrosis, which was localized in the inner cortex and the outer stripe of the outer medulla, was significantly different from that observed in Mrp2-deficient animals. These findings suggest that Bcrp may be involved in the cellular export of select mercuric species and that its role in this export may differ from that of Mrp2. - Highlights: • Bcrp may mediate transport of mercury out of proximal tubular cells. • Hg-induced nephropathy was more severe in Bcrp knockout rats. • Bcrp and Mrp2 may differ in their ability to transport Hg.« less

Curcumin suppresses AGEs induced apoptosis in tubular epithelial cells via protective autophagy

PubMed Central

Wei, Ying; Gao, Jiaqi; Qin, Lingling; Xu, Yunling; Shi, Haoxia; Qu, Lingxia; Liu, Yongqiao; Xu, Tunhai; Liu, Tonghua

2017-01-01

Renal tubular cell apoptosis and tubular dysfunction is an important process underlying diabetic nephropathy (DN). Understanding the mechanisms underlying renal tubular epithelial cell survival is important for the prevention of kidney damage associated with glucotoxicity. Curcumin has been demonstrated to possess potent anti-apoptotic properties. However, the roles of curcumin in renal epithelial cells are yet to be defined. The present study investigated advanced glycation or glycoxidation end-product (AGE)-induced toxicity in renal tubular epithelial cells via several complementary assays, including cell viability, cell apoptosis and cell autophagy in the NRK-52E rat kidney tubular epithelial cell line. The extent of apoptosis was significantly increased in the NRK-52E cells following treatment with AGEs. The results also indicated that curcumin reversed this effect by promoting autophagy through the phosphoinositide 3-kinase/AKT serine/threonine kinase signaling pathway. These conclusions suggested that curcumin exerts a renoprotective effect in the presence of AGEs, at least in part by activating autophagy in NRK-52E cells. Collectively, these findings indicate that curcumin not only exerts renoprotective effects, however may also act as a novel therapeutic strategy for the treatment of diabetic nephropathy. PMID:29285156

Nano-Tubular Cellulose for Bioprocess Technology Development

PubMed Central

Koutinas, Athanasios A.; Sypsas, Vasilios; Kandylis, Panagiotis; Michelis, Andreas; Bekatorou, Argyro; Kourkoutas, Yiannis; Kordulis, Christos; Lycourghiotis, Alexis; Banat, Ibrahim M.; Nigam, Poonam; Marchant, Roger; Giannouli, Myrsini; Yianoulis, Panagiotis

2012-01-01

Delignified cellulosic material has shown a significant promotional effect on the alcoholic fermentation as yeast immobilization support. However, its potential for further biotechnological development is unexploited. This study reports the characterization of this tubular/porous cellulosic material, which was done by SEM, porosimetry and X-ray powder diffractometry. The results showed that the structure of nano-tubular cellulose (NC) justifies its suitability for use in “cold pasteurization” processes and its promoting activity in bioprocessing (fermentation). The last was explained by a glucose pump theory. Also, it was demonstrated that crystallization of viscous invert sugar solutions during freeze drying could not be otherwise achieved unless NC was present. This effect as well as the feasibility of extremely low temperature fermentation are due to reduction of the activation energy, and have facilitated the development of technologies such as wine fermentations at home scale (in a domestic refrigerator). Moreover, NC may lead to new perspectives in research such as the development of new composites, templates for cylindrical nano-particles, etc. PMID:22496794

Berberine activates Nrf2 nuclear translocation and inhibits apoptosis induced by high glucose in renal tubular epithelial cells through a phosphatidylinositol 3-kinase/Akt-dependent mechanism.

PubMed

Zhang, Xiuli; Liang, Dan; Lian, Xu; Jiang, Yan; He, Hui; Liang, Wei; Zhao, Yue; Chi, Zhi-Hong

2016-06-01

Apoptosis of tubular epithelial cells is a major feature of diabetic kidney disease, and hyperglycemia triggers the generation of free radicals and oxidant stress in tubular cells. Berberine (BBR) is identified as a potential anti-diabetic herbal medicine due to its beneficial effects on insulin sensitivity, glucose metabolism and glycolysis. In this study, the underlying mechanisms involved in the protective effects of BBR on high glucose-induced apoptosis were explored using cultured renal tubular epithelial cells (NRK-52E cells) and human kidney proximal tubular cell line (HK-2 cells). We identified the pivotal role of phosphatidylinositol 3-kinase (PI3K)/Akt in BBR cellular defense mechanisms and revealed the novel effect of BBR on nuclear factor (erythroid-derived 2)-related factor-2 (Nrf2) and heme oxygenase (HO)-1 in NRK-52E and HK-2 cells. BBR attenuated reactive oxygen species production, antioxidant defense (GSH and SOD) and oxidant-sensitive proteins (Nrf2 and HO-1), which also were blocked by LY294002 (an inhibitor of PI3K) in HG-treated NRK-52E and HK-2 cells. Furthermore, BBR improved mitochondrial function by increasing mitochondrial membrane potential. BBR-induced anti-apoptotic function was demonstrated by decreasing apoptotic proteins (cytochrome c, Bax, caspase3 and caspase9). All these findings suggest that BBR exerts the anti-apoptosis effects through activation of PI3K/Akt signal pathways and leads to activation of Nrf2 and induction of Nrf2 target genes, and consequently protecting the renal tubular epithelial cells from HG-induced apoptosis.

Pituitary adenylate cyclase-activating polypeptide promotes eccrine gland sweat secretion.

PubMed

Sasaki, S; Watanabe, J; Ohtaki, H; Matsumoto, M; Murai, N; Nakamachi, T; Hannibal, J; Fahrenkrug, J; Hashimoto, H; Watanabe, H; Sueki, H; Honda, K; Miyazaki, A; Shioda, S

2017-02-01

Sweat secretion is the major function of eccrine sweat glands; when this process is disturbed (paridrosis), serious skin problems can arise. To elucidate the causes of paridrosis, an improved understanding of the regulation, mechanisms and factors underlying sweat production is required. Pituitary adenylate cyclase-activating polypeptide (PACAP) exhibits pleiotropic functions that are mediated via its receptors [PACAP-specific receptor (PAC1R), vasoactive intestinal peptide (VIP) receptor type 1 (VPAC1R) and VPAC2R]. Although some studies have suggested a role for PACAP in the skin and several exocrine glands, the effects of PACAP on the process of eccrine sweat secretion have not been examined. To investigate the effect of PACAP on eccrine sweat secretion. Reverse transcriptase-polymerase chain reaction and immunostaining were used to determine the expression and localization of PACAP and its receptors in mouse and human eccrine sweat glands. We injected PACAP subcutaneously into the footpads of mice and used the starch-iodine test to visualize sweat-secreting glands. Immunostaining showed PACAP and PAC1R expression by secretory cells from mouse and human sweat glands. PACAP immunoreactivity was also localized in nerve fibres around eccrine sweat glands. PACAP significantly promoted sweat secretion at the injection site, and this could be blocked by the PAC1R-antagonist PACAP6-38. VIP, an agonist of VPAC1R and VPAC2R, failed to induce sweat secretion. This is the first report demonstrating that PACAP may play a crucial role in sweat secretion via its action on PAC1R located in eccrine sweat glands. The mechanisms underlying the role of PACAP in sweat secretion may provide new therapeutic options to combat sweating disorders. © 2016 British Association of Dermatologists.

Smart concrete slabs with embedded tubular PZT transducers for damage detection

NASA Astrophysics Data System (ADS)

Gao, Weihang; Huo, Linsheng; Li, Hongnan; Song, Gangbing

2018-02-01

The objective of this study is to develop a new concept and methodology of smart concrete slab (SCS) with embedded tubular lead zirconate titanate transducer array for image based damage detection. Stress waves, as the detecting signals, are generated by the embedded tubular piezoceramic transducers in the SCS. Tubular piezoceramic transducers are used due to their capacity of generating radially uniform stress waves in a two-dimensional concrete slab (such as bridge decks and walls), increasing the monitoring range. A circular type delay-and-sum (DAS) imaging algorithm is developed to image the active acoustic sources based on the direct response received by each sensor. After the scattering signals from the damage are obtained by subtracting the baseline response of the concrete structures from those of the defective ones, the elliptical type DAS imaging algorithm is employed to process the scattering signals and reconstruct the image of the damage. Finally, two experiments, including active acoustic source monitoring and damage imaging for concrete structures, are carried out to illustrate and demonstrate the effectiveness of the proposed method.

METHOD AND APPARATUS FOR FABRICATING TUBULAR UNITS

DOEpatents

Haldeman, G.W.

1959-02-24

A method and apparatus are described for fabricating tubular assemblies such as clad fuel elements for nuclear reactors. According to this method, a plurality of relatively short cylindrical slug-shaped members are inserted in an outer protective tubular jacket, and the assembly is passed through a reducing die to draw the outer tubular member into tight contact with the slug members, the slugs being automatically spaced with respect to each other and helium being inserted during the drawing operation to fill the spaces. The apparatus includes a pusher rod which functions to space the slugelements equidistantly by pushing on them in the direction of drawing but traveling at a slower rate than that of the tubular member.

Stretch-Induced Hypertrophy Activates NFkB-Mediated VEGF Secretion in Adult Cardiomyocytes

PubMed Central

Leychenko, Anna; Konorev, Eugene; Jijiwa, Mayumi; Matter, Michelle L.

2011-01-01

Hypertension and myocardial infarction are associated with the onset of hypertrophy. Hypertrophy is a compensatory response mechanism to increases in mechanical load due to pressure or volume overload. It is characterized by extracellular matrix remodeling and hypertrophic growth of adult cardiomyocytes. Production of Vascular Endothelial Growth Factor (VEGF), which acts as an angiogenic factor and a modulator of cardiomyocyte function, is regulated by mechanical stretch. Mechanical stretch promotes VEGF secretion in neonatal cardiomyocytes. Whether this effect is retained in adult cells and the molecular mechanism mediating stretch-induced VEGF secretion has not been elucidated. Our objective was to investigate whether cyclic mechanical stretch induces VEGF secretion in adult cardiomyocytes and to identify the molecular mechanism mediating VEGF secretion in these cells. Isolated primary adult rat cardiomyocytes (ARCMs) were subjected to cyclic mechanical stretch at an extension level of 10% at 30 cycles/min that induces hypertrophic responses. Cyclic mechanical stretch induced a 3-fold increase in VEGF secretion in ARCMs compared to non-stretch controls. This increase in stretch-induced VEGF secretion correlated with NFkB activation. Cyclic mechanical stretch-mediated VEGF secretion was blocked by an NFkB peptide inhibitor and expression of a dominant negative mutant IkBα, but not by inhibitors of the MAPK/ERK1/2 or PI3K pathways. Chromatin immunoprecipitation assays demonstrated an interaction of NFkB with the VEGF promoter in stretched primary cardiomyocytes. Moreover, VEGF secretion is increased in the stretched myocardium during pressure overload-induced hypertrophy. These findings are the first to demonstrate that NFkB activation plays a role in mediating VEGF secretion upon cyclic mechanical stretch in adult cardiomyocytes. Signaling by NFkB initiated in response to cyclic mechanical stretch may therefore coordinate the hypertrophic response in adult

Pancreatic β-Cell Electrical Activity and Insulin Secretion: of Mice and Men

PubMed Central

Rorsman, Patrik; Ashcroft, Frances M

2018-01-01

The pancreatic β-cell plays a key role in glucose homeostasis by secreting insulin, the only hormone capable of lowering the blood glucose concentration. Impaired insulin secretion results in the chronic hyperglycaemia that characterizes type 2 diabetes (T2DM), which currently afflicts >450 million people worldwide. The healthy β-cell acts as a glucose sensor matching its output to the circulating glucose concentration. It does so via metabolically induced changes in electrical activity, which culminate in an increase in the cytoplasmic Ca2+ concentration and initiation of Ca2+-dependent exocytosis of insulin-containing secretory granules. Here, we review recent advances in our understanding of the β-cell transcriptome, electrical activity and insulin exocytosis. We highlight salient differences between mouse and human β-cells, provide models of how the different ion channels contribute to their electrical activity and insulin secretion, and conclude by discussing how these processes become perturbed in T2DM. PMID:29212789

Activating mutations in STIM1 and ORAI1 cause overlapping syndromes of tubular myopathy and congenital miosis

PubMed Central

Nesin, Vasyl; Wiley, Graham; Kousi, Maria; Ong, E-Ching; Lehmann, Thomas; Nicholl, David J.; Suri, Mohnish; Shahrizaila, Nortina; Katsanis, Nicholas; Gaffney, Patrick M.; Wierenga, Klaas J.; Tsiokas, Leonidas

2014-01-01

Signaling through the store-operated Ca2+ release-activated Ca2+ (CRAC) channel regulates critical cellular functions, including gene expression, cell growth and differentiation, and Ca2+ homeostasis. Loss-of-function mutations in the CRAC channel pore-forming protein ORAI1 or the Ca2+ sensing protein stromal interaction molecule 1 (STIM1) result in severe immune dysfunction and nonprogressive myopathy. Here, we identify gain-of-function mutations in the cytoplasmic domain of STIM1 (p.R304W) associated with thrombocytopenia, bleeding diathesis, miosis, and tubular myopathy in patients with Stormorken syndrome, and in ORAI1 (p.P245L), associated with a Stormorken-like syndrome of congenital miosis and tubular aggregate myopathy but without hematological abnormalities. Heterologous expression of STIM1 p.R304W results in constitutive activation of the CRAC channel in vitro, and spontaneous bleeding accompanied by reduced numbers of thrombocytes in zebrafish embryos, recapitulating key aspects of Stormorken syndrome. p.P245L in ORAI1 does not make a constitutively active CRAC channel, but suppresses the slow Ca2+-dependent inactivation of the CRAC channel, thus also functioning as a gain-of-function mutation. These data expand our understanding of the phenotypic spectrum of dysregulated CRAC channel signaling, advance our knowledge of the molecular function of the CRAC channel, and suggest new therapies aiming at attenuating store-operated Ca2+ entry in the treatment of patients with Stormorken syndrome and related pathologic conditions. PMID:24591628

Arcas Rocket with Special Tubular Launcher

NASA Image and Video Library

1959-07-31

Arcas Rocket with Special Tubular Launcher: Lt. Commander W. Houston checks elevation adjustment of special tubular launcher for Arcas rocket, July 31, 1959. Photograph published in A New Dimension Wallops Island Flight Test Range: The First Fifteen Years by Joseph Shortal. A NASA publication. Page 697.

Tubular copper thrust chamber design study

NASA Technical Reports Server (NTRS)

Masters, A. I.; Galler, D. E.

1992-01-01

The use of copper tubular thrust chambers is particularly important in high performance expander cycle space engines. Tubular chambers have more surface area than flat wall chambers, and this extra surface area provides enhanced heat transfer for additional energy to power the cycle. This paper was divided into two sections: (1) a thermal analysis and sensitivity study; and (2) a preliminary design of a selected thrust chamber configuration. The thermal analysis consisted of a statistical optimization to determine the optimum tube geometry, tube booking, thrust chamber geometry, and cooling routing to achieve the maximum upper limit chamber pressure for a 25,000 pound thrust engine. The preliminary design effort produced a layout drawing of a tubular thrust chamber that is three inches shorter than the Advanced Expander Test Bed (AETB) milled channel chamber but is predicted to provide a five percent increase in heat transfer. Testing this chamber in the AETB would confirm the inherent advantages of tubular chamber construction and heat transfer.

Histone deacetylase inhibitors protect against cisplatin-induced acute kidney injury by activating autophagy in proximal tubular cells.

PubMed

Liu, Jing; Livingston, Man J; Dong, Guie; Tang, Chengyuan; Su, Yunchao; Wu, Guangyu; Yin, Xiao-Ming; Dong, Zheng

2018-02-23

Histone deacetylase inhibitors (HDACi) have therapeutic effects in models of various renal diseases including acute kidney injury (AKI); however, the underlying mechanism remains unclear. Here we demonstrate that two widely tested HDACi (suberoylanilide hydroxamic acid (SAHA) and trichostatin A (TSA)) protect the kidneys in cisplatin-induced AKI by enhancing autophagy. In cultured renal proximal tubular cells, SAHA and TSA enhanced autophagy during cisplatin treatment. We further verified the protective effect of TSA against cisplatin-induced apoptosis in these cells. Notably, inhibition of autophagy by chloroquine or by autophagy gene 7 (Atg7) ablation diminished the protective effect of TSA. In mice, TSA increased autophagy in renal proximal tubules and protected against cisplatin-induced AKI. The in vivo effect of TSA was also abolished by chloroquine and by Atg7 knockout specifically from renal proximal tubules. Mechanistically, TSA stimulated AMPK and inactivated mTOR during cisplatin treatment of proximal tubule cells and kidneys in mice. Together, these results suggest that HDACi may protect kidneys by activating autophagy in proximal tubular cells.

Xenin Augments Duodenal Anion Secretion via Activation of Afferent Neural Pathways

PubMed Central

Kaji, Izumi; Akiba, Yasutada; Kato, Ikuo; Maruta, Koji; Kuwahara, Atsukazu

2017-01-01

Xenin-25, a neurotensin (NT)-related anorexigenic gut hormone generated mostly in the duodenal mucosa, is believed to increase the rate of duodenal ion secretion, because xenin-induced diarrhea is not present after Roux-en-Y gastric bypass surgery. Because the local effects of xenin on duodenal ion secretion have remained uninvestigated, we thus examined the neural pathways underlying xenin-induced duodenal anion secretion. Intravenous infusion of xenin-8, a bioactive C-terminal fragment of xenin-25, dose dependently increased the rate of duodenal HCO3− secretion in perfused duodenal loops of anesthetized rats. Xenin was immunolocalized to a subset of enteroendocrine cells in the rat duodenum. The mRNA of the xenin/NT receptor 1 (NTS1) was predominantly expressed in the enteric plexus, nodose and dorsal root ganglia, and in the lamina propria rather than in the epithelium. The serosal application of xenin-8 or xenin-25 rapidly and transiently increased short-circuit current in Ussing-chambered mucosa-submucosa preparations in a concentration-dependent manner in the duodenum and jejunum, but less so in the ileum and colon. The selective antagonist for NTS1, substance P (SP) receptor (NK1), or 5-hydroxytryptamine (5-HT)3, but not NTS2, inhibited the responses to xenin. Xenin-evoked Cl- secretion was reduced by tetrodotoxin (TTX) or capsaicin-pretreatment, and abolished by the inhibitor of TTX-resistant sodium channel Nav1.8 in combination with TTX, suggesting that peripheral xenin augments duodenal HCO3− and Cl− secretion through NTS1 activation on intrinsic and extrinsic afferent nerves, followed by release of SP and 5-HT. Afferent nerve activation by postprandial, peripherally released xenin may account for its secretory effects in the duodenum. PMID:28115552

Basolateral K+ channel involvement in forskolin-activated chloride secretion in human colon

PubMed Central

McNamara, Brian; Winter, Desmond C; Cuffe, John E; O'Sullivan, Gerald C; Harvey, Brian J

1999-01-01

In this study we investigated the role of basolateral potassium transport in maintaining cAMP-activated chloride secretion in human colonic epithelium. Ion transport was quantified in isolated human colonic epithelium using the short-circuit current technique. Basolateral potassium transport was studied using nystatin permeabilization. Intracellular calcium measurements were obtained from isolated human colonic crypts using fura-2 spectrofluorescence imaging. In intact isolated colonic strips, forskolin and prostaglandin E2 (PGE2) activated an inward transmembrane current (ISC) consistent with anion secretion (for forskolin ΔISC = 63.8 ± 6.2 μA cm−2, n = 6; for PGE2 ΔISC = 34.3 ± 5.2 μA cm−2, n = 6). This current was inhibited in chloride-free Krebs solution or by inhibiting basolateral chloride uptake with bumetanide and 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS). The forskolin- and PGE2-induced chloride secretion was inhibited by basolateral exposure to barium (5 mM), tetrapentylammonium (10 μM) and tetraethylammonium (10 mM). The transepithelial current produced under an apical to serosal K+ gradient in nystatin-perforated colon is generated at the basolateral membrane by K+ transport. Forskolin failed to activate this current under conditions of high or low calcium and failed to increase the levels of intracellular calcium in isolated crypts In conclusion, we propose that potassium recycling through basolateral K+ channels is essential for cAMP-activated chloride secretion. PMID:10432355

Ontogeny of flow-stimulated potassium secretion in rabbit cortical collecting duct: functional and molecular aspects.

PubMed

Woda, Craig B; Miyawaki, Nobuyuki; Ramalakshmi, Santhanam; Ramkumar, Mohan; Rojas, Raul; Zavilowitz, Beth; Kleyman, Thomas R; Satlin, Lisa M

2003-10-01

High urinary flow rates stimulate K secretion in the fully differentiated but not neonatal or weanling rabbit cortical collecting duct (CCD). Both small-conductance secretory K and high-conductance Ca2+/stretch-activated maxi-K channels have been identified in the apical membrane of the mature CCD by patch-clamp analysis. We reported that flow-stimulated net K secretion in the adult rabbit CCD is 1) blocked by TEA and charybdotoxin, inhibitors of intermediate- and high-conductance (maxi-K) Ca2+-activated K channels, and 2) associated with increases in net Na absorption and intracellular Ca2+ concentration ([Ca2+]i). The present study examined whether the absence of flow-stimulated K secretion early in life is due to a 1) limited flow-induced rise in net Na absorption and/or [Ca2+]i and/or 2) paucity of apical maxi-K channels. An approximately sixfold increase in tubular fluid flow rate in CCDs isolated from 4-wk-old rabbits and microperfused in vitro led to an increase in net Na absorption and [Ca2+]i, similar in magnitude to the response observed in 6-wk-old tubules, but it failed to generate an increase in net K secretion. By 5 wk of age, there was a small, but significant, flow-stimulated rise in net K secretion that increased further by 6 wk of life. Luminal perfusion with iberiotoxin blocked the flow stimulation of net K secretion in the adult CCD, confirming the identity of the maxi-K channel in this response. Maxi-K channel alpha-subunit message was consistently detected in single CCDs from animals >/=4 wk of age by RT-PCR. Indirect immunofluorescence microscopy using antibodies directed against the alpha-subunit revealed apical labeling of intercalated cells in cryosections from animals >/=5 wk of age; principal cell labeling was generally intracellular and punctate. We speculate that the postnatal appearance of flow-dependent K secretion is determined by the transcriptional/translational regulation of expression of maxi-K channels. Furthermore, our studies

A new tubular hot-wire CVD for diamond coating

NASA Astrophysics Data System (ADS)

Motahari, Hamid; Bellah, Samad Moemen; Malekfar, Rasoul

2017-06-01

A new tubular hot-wire chemical vapor deposition (HWCVD) system using a tubular quartz vacuum chamber has been fabricated. The filaments in this system can heat the substrate and act as a gas activator and thermally activator for gas species at the same time. The nano- and microcrystalline diamond coatings on the surface of steel AISI 316 substrates have been grown. To assess the results, SEM and FESEM images and Raman spectroscopy investigations have been applied. The results reveal that micro- and nanocrystalline diamond structures have been formed in the coatings, but the disordered diamond and some non-diamond phases, such as graphitic carbons, are also present in the coating layers. The analytical measurements show the growth of diamond films with well-faceted crystals in (111) direction. However, intrinsic stress, secondary nucleation, and poor adhesion are the main issues of future research for this new designed HWCVD.

Diabetes and renal tubular cell apoptosis

PubMed Central

Habib, Samy L

2013-01-01

Apoptosis contributes to the development of diabetic nephropathy, but the mechanism by which high glucose induces apoptosis is not fully understood. Apoptosis of tubular epithelial cells is a major feature of diabetic kidney disease, and hyperglycemia triggers the generation of free radicals and oxidant stress in tubular cells. Hyperglycemia and high glucose in vitro also lead to apoptosis, a form of programmed cell death. High glucose similar to those seen with hyperglycemia in people with diabetes mellitus, lead to accelerated apoptosis, a form of programmed cell death characterized by cell shrinkage, chromatin condensation and DNA fragmentation, in variety of cell types, including renal proximal tubular epithelial cells. PMID:23593533

Diabetes and renal tubular cell apoptosis.

PubMed

Habib, Samy L

2013-04-15

Apoptosis contributes to the development of diabetic nephropathy, but the mechanism by which high glucose induces apoptosis is not fully understood. Apoptosis of tubular epithelial cells is a major feature of diabetic kidney disease, and hyperglycemia triggers the generation of free radicals and oxidant stress in tubular cells. Hyperglycemia and high glucose in vitro also lead to apoptosis, a form of programmed cell death. High glucose similar to those seen with hyperglycemia in people with diabetes mellitus, lead to accelerated apoptosis, a form of programmed cell death characterized by cell shrinkage, chromatin condensation and DNA fragmentation, in variety of cell types, including renal proximal tubular epithelial cells.

VEGF secretion during hypoxia depends on free radicals-induced Fyn kinase activity in mast cells

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

Garcia-Roman, Jonathan; Ibarra-Sanchez, Alfredo; Lamas, Monica

2010-10-15

Research highlights: {yields} Bone marrow-derived mast cells (BMMCs) secrete functional VEGF but do not degranulate after Cobalt chloride-induced hypoxia. {yields} CoCl{sub 2}-induced VEGF secretion in mast cells occurs by a Ca{sup 2+}-insensitive but brefeldin A and Tetanus toxin-sensitive mechanism. {yields} Trolox and N-acetylcysteine inhibit hypoxia-induced VEGF secretion but only Trolox inhibits Fc{epsilon}RI-dependent anaphylactic degranulation in mast cells. {yields} Src family kinase Fyn activation after free radical production is necessary for hypoxia-induced VEGF secretion in mast cells. -- Abstract: Mast cells (MC) have an important role in pathologic conditions such as asthma and chronic obstructive pulmonary disease (COPD), where hypoxia conducemore » to deleterious inflammatory response. MC contribute to hypoxia-induced angiogenesis producing factors such as vascular endothelial growth factor (VEGF), but the mechanisms behind the control of hypoxia-induced VEGF secretion in this cell type is poorly understood. We used the hypoxia-mimicking agent cobalt chloride (CoCl{sub 2}) to analyze VEGF secretion in murine bone marrow-derived mast cells (BMMCs). We found that CoCl{sub 2} promotes a sustained production of functional VEGF, able to induce proliferation of endothelial cells in vitro. CoCl{sub 2}-induced VEGF secretion was independent of calcium rise but dependent on tetanus toxin-sensitive vesicle-associated membrane proteins (VAMPs). VEGF exocytosis required free radicals formation and the activation of Src family kinases. Interestingly, an important deficiency on CoCl{sub 2}-induced VEGF secretion was observed in Fyn kinase-deficient BMMCs. Moreover, Fyn kinase was activated by CoCl{sub 2} in WT cells and this activation was prevented by treatment with antioxidants such as Trolox and N-acetylcysteine. Our results show that BMMCs are able to release VEGF under hypoxic conditions through a tetanus toxin-sensitive mechanism, promoted by free

Isolation and Characterization of Escherichia coli tolC Mutants Defective in Secreting Enzymatically Active Alpha-Hemolysin

PubMed Central

Vakharia, Hema; German, Greg J.; Misra, Rajeev

2001-01-01

This study describes the isolation and characterization of a unique class of TolC mutants that, under steady-state growth conditions, secreted normal levels of largely inactive alpha-hemolysin. Unlike the reduced activity in the culture supernatants, the cell-associated hemolytic activity in these mutants was identical to that in the parental strain, thus reflecting a normal intracellular toxin activation event. Treatment of the secreted toxin with guanidine hydrochloride significantly restored cytolytic activity, suggesting that the diminished activity may have been due to the aggregation or misfolding of the toxin molecules. Consistent with this notion, sedimentation and filtration analyses showed that alpha-hemolysin secreted from the mutant strain has a mass greater than that secreted from the parental strain. Experiments designed to monitor the time course of alpha-hemolysin release showed delayed appearance of toxin in the culture supernatant of the mutant strain, thus indicating a possible defect in alpha-hemolysin translocation or release. Eight different TolC substitutions displaying this toxin secretion defect were scattered throughout the protein, of which six localized in the periplasmically exposed α-helical domain, while the remaining two mapped within the outer membrane-embedded β-barrel domain of TolC. A plausible model for the secretion of inactive alpha-hemolysin in these TolC mutants is discussed in the context of the recently determined three-dimensional structure of TolC. PMID:11698380

ISOLATION AND CHARACTERIZATION OF LAMELLAR BODIES AND TUBULAR MYELIN FROM RAT LUNG HOMOGENATES

PubMed Central

Gil, Joan; Reiss, Oscar K.

1973-01-01

Three surface-active fractions which differ in their morphology have been isolated from rat lung homogenates by ultracentrifugation in a discontinuous sucrose density gradient. In order of increasing density, the fractions consisted, as shown by electron microscopy, primarily of common myelin figures, lamellar bodies, and tubular myelin figures. The lipid of all three fractions contained approximately 94% polar lipids and 2% cholesterol. In the case of the common myelin figures and the lamellar bodies, the polar lipids consisted of 73% phosphatidylcholines, 9% phosphatidylserines and inositols, and 8% phosphatidylethanolamines. In the case of the tubular myelin figures, the respective percentages were 58, 19, and 5. Over 90% of the fatty acids of the lecithins of all three fractions were saturated. Electrophoresis of the proteins of the fractions in sodium dodecyl sulfate or Triton X-100 revealed that the lamellar bodies and the tubular myelin figures differed in the mobilities of their proteins. The common myelin figures, however, contained proteins from both of the other fractions. These data indicate that, whereas the lipids of the extracellular, alveolar surfactant(s) originate in the lamellar bodies, the proteins arise from another source. It is further postulated that the tubular myelin figures represent a liquid crystalline state of the alveolar surface-active lipoproteins. PMID:4726305

Dietary sodium induces a redistribution of the tubular metabolic workload

PubMed Central

Udwan, Khalil; Abed, Ahmed; Roth, Isabelle; Dizin, Eva; Maillard, Marc; Bettoni, Carla; Loffing, Johannes; Wagner, Carsten A.; Edwards, Aurélie

2017-01-01

. Mathematical modelling predicted that tubular Na+ reabsorption decreased in the proximal tubule but increased in distal segments with lower transport efficiency with respect to O2 consumption. This prediction was confirmed by the natriuretic response to diuretics. The activity of the metabolic sensor adenosine monophosphate‐activated protein kinase (AMPK) was related to the changes in tubular Na+ reabsorption. Our data show that fractional Na+ reabsorption is distributed differently according to dietary Na+ intake and induces changes in tubular O2 consumption and sodium transport efficiency. PMID:28940314

Neurogenic regulation of renal tubular sodium reabsorption.

PubMed

DiBona, G F

1977-08-01

The evidence supporting a role for direct neurogenic control of renal tubular sodium reabsorption is reviewed. Electron microscopic and fluorescence histochemical studies have demonstrated adrenergic nerve terminals in direct contact with basement membranes of mammalian (rat, dog, and monkey) renal tubular epithelial cells. Low-level direct or baroreceptor reflex stimulation of renal sympathetic nerves produces an increase in renal tubular sodium reabsorption without alterations in glomerular filtration rate, renal blood flow, or intrarenal distribution of blood flow. Antinatriuresis was prevented by prior treatment of the kidney with guanethidine or phenoxybenzamine. Rat kidney micropuncture studies have localized a site of enhanced tubular sodium reabsorption to the proximal tubule. Possible indirect mediation of the antinatriuresis by other humoral agents known to be released from the kidney on renal nerve stimulation (angiotensin II, prostaglandin) was excluded by experiments with appropriate blocking agents. The possible effects of anesthesia and uncertainties about the completeness of surgical renal denervation and other tubular segmental sites of action are critically analyzed. The clinical implications of this mechanism in pathologic conditions of sodium and water retention are discussed and and a prospectus for future work is presented.

Passive driving forces of proximal tubular fluid and bicarbonate transport: gradient dependence of H+ secretion.

PubMed

Chan, Y L; Malnic, G; Giebisch, G

1983-11-01

The effect of oncotic pressure changes on fluid (Jv) and net bicarbonate transport (JHCO-3) and the transepithelial bicarbonate permeability (PHCO-3) were measured by an improved luminal and capillary microperfusion method that allows paired experiments on the same tubule. Rat proximal tubules were pump-perfused and Jv and [HCO-3] measured with [14C]inulin and a pH glass electrode. Raising peritubular protein (0-8-15 g/100 ml bovine serum albumin) stimulated Jv and HCO-3 reabsorption. The response to oncotic pressure changes was asymmetrical since changes of the luminal protein concentration had no significant effects. Whereas transepithelial solvent drag effects on HCO-3 must be minimal, peritubular protein most likely stimulates translocation of fluid and bicarbonate from intercellular spaces into peritubular capillaries. PHCO-3 was measured from HCO-3 net flux along a lumen-to-capillary-directed electrochemical potential gradient. In these experiments active H+ transport and Jv were minimized by 10(-4) M acetazolamide and luminal raffinose. PHCO-3 was 1.77 X 10(-5) cm X s-1 and was unaffected by increasing luminal flow rate from 10 to 45 nl X min-1. Since bicarbonate backflux is only a small fraction of physiological rates of JHCO-3, net transport alterations at varying [HCO-3] in the lumen must be due to changes in active HCO-3 (H+) transport. Thus, active H+ ion secretion across the luminal membrane of the proximal tubule is gradient dependent.

Substrates Control Multimerization and Activation of the Multi-Domain ATPase Motor of Type VII Secretion

DOE PAGES

Rosenberg, Oren S.; Dovala, Dustin; Li, Xueming; ...

2015-04-09

We report that Mycobacterium tuberculosis and Staphylococcus aureus secrete virulence factors via type VII protein secretion (T7S), a system that intriguingly requires all of its secretion substrates for activity. To gain insights into T7S function, we used structural approaches to guide studies of the putative translocase EccC, a unique enzyme with three ATPase domains, and its secretion substrate EsxB. The crystal structure of EccC revealed that the ATPase domains are joined by linker/pocket interactions that modulate its enzymatic activity. EsxB binds via its signal sequence to an empty pocket on the C-terminal ATPase domain, which is accompanied by an increasemore » in ATPase activity. Surprisingly, substrate binding does not activate EccC allosterically but, rather, by stimulating its multimerization. Thus, the EsxB substrate is also an integral T7S component, illuminating a mechanism that helps to explain interdependence of substrates, and suggests a model in which binding of substrates modulates their coordinate release from the bacterium.« less

Exosome production and its regulation of EGFR during wound healing in renal tubular cells.

PubMed

Zhou, Xiangjun; Zhang, Wei; Yao, Qisheng; Zhang, Hao; Dong, Guie; Zhang, Ming; Liu, Yutao; Chen, Jian-Kang; Dong, Zheng

2017-06-01

Kidney repair following injury involves the reconstitution of a structurally and functionally intact tubular epithelium. Growth factors and their receptors, such as EGFR, are important in the repair of renal tubules. Exosomes are cell-produced small (~100 nm in diameter) vesicles that contain and transfer proteins, lipids, RNAs, and DNAs between cells. In this study, we examined the relationship between exosome production and EGFR activation and the potential role of exosome in wound healing. EGFR activation occurred shortly after scratch wounding in renal tubular cells. Wound repair after scratching was significantly promoted by EGF and suppressed by EGFR inhibitor gefitinib. Interestingly, scratch wounding induced a significant increase of exosome production. The exosome production was decreased by EGF and increased by gefitinib, suggesting a suppressive role of EGFR signaling in exosome production. Conversely, inhibition of exosome release by GW4869 and manumycin A markedly increased EGFR activation and promoted wound healing. Moreover, exosomes derived from scratch-wounding cells could inhibit wound healing. Collectively, the results indicate that wound healing in renal tubular cells is associated with EGFR activation and exosome production. Although EGFR activation promotes wound healing, released exosomes may antagonize EGFR activation and wound healing. Copyright © 2017 the American Physiological Society.

Reduced active transcellular intestinal oxalate secretion contributes to the pathogenesis of obesity-associated hyperoxaluria.

PubMed

Amin, Ruhul; Asplin, John; Jung, Daniel; Bashir, Mohamed; Alshaikh, Altayeb; Ratakonda, Sireesha; Sharma, Sapna; Jeon, Sohee; Granja, Ignacio; Matern, Dietrich; Hassan, Hatim

2018-05-01

Most kidney stones are composed of calcium oxalate, and minor changes in urine oxalate affect the stone risk. Obesity is a risk factor for kidney stones and a positive correlation of unknown etiology between increased body size, and elevated urinary oxalate excretion has been reported. Here, we used obese ob/ob (ob) mice to elucidate the pathogenesis of obesity-associated hyperoxaluria. These ob mice have significant hyperoxaluria (3.3-fold) compared with control mice, which is not due to overeating as shown by pair-feeding studies. Dietary oxalate removal greatly ameliorated this hyperoxaluria, confirming that it is largely enteric in origin. Transporter SLC26A6 (A6) plays an essential role in active transcellular intestinal oxalate secretion, and ob mice have significantly reduced jejunal A6 mRNA (- 80%) and total protein (- 62%) expression. While net oxalate secretion was observed in control jejunal tissues mounted in Ussing chambers, net absorption was seen in ob tissues, due to significantly reduced secretion. We hypothesized that the obesity-associated increase in intestinal and systemic inflammation, as reflected by elevated proinflammatory cytokines, suppresses A6-mediated intestinal oxalate secretion and contributes to obesity-associated hyperoxaluria. Indeed, proinflammatory cytokines (elevated in ob mice) significantly decreased intestinal oxalate transport in vitro by reducing A6 mRNA and total protein expression. Proinflammatory cytokines also significantly reduced active mouse jejunal oxalate secretion, converting oxalate transport from net secretion in vehicle-treated tissues to net absorption in proinflammatory cytokines-treated tissues. Thus, reduced active intestinal oxalate secretion, likely secondary to local and systemic inflammation, contributes to the pathogenesis of obesity-associated hyperoxaluria. Hence, proinflammatory cytokines represent potential therapeutic targets. Copyright © 2017 International Society of Nephrology. Published by

β-Cell–Specific Protein Kinase A Activation Enhances the Efficiency of Glucose Control by Increasing Acute-Phase Insulin Secretion

PubMed Central

Kaihara, Kelly A.; Dickson, Lorna M.; Jacobson, David A.; Tamarina, Natalia; Roe, Michael W.; Philipson, Louis H.; Wicksteed, Barton

2013-01-01

Acute insulin secretion determines the efficiency of glucose clearance. Moreover, impaired acute insulin release is characteristic of reduced glucose control in the prediabetic state. Incretin hormones, which increase β-cell cAMP, restore acute-phase insulin secretion and improve glucose control. To determine the physiological role of the cAMP-dependent protein kinase (PKA), a mouse model was developed to increase PKA activity specifically in the pancreatic β-cells. In response to sustained hyperglycemia, PKA activity potentiated both acute and sustained insulin release. In contrast, a glucose bolus enhanced acute-phase insulin secretion alone. Acute-phase insulin secretion was increased 3.5-fold, reducing circulating glucose to 58% of levels in controls. Exendin-4 increased acute-phase insulin release to a similar degree as PKA activation. However, incretins did not augment the effects of PKA on acute-phase insulin secretion, consistent with incretins acting primarily via PKA to potentiate acute-phase insulin secretion. Intracellular calcium signaling was unaffected by PKA activation, suggesting that the effects of PKA on acute-phase insulin secretion are mediated by the phosphorylation of proteins involved in β-cell exocytosis. Thus, β-cell PKA activity transduces the cAMP signal to dramatically increase acute-phase insulin secretion, thereby enhancing the efficiency of insulin to control circulating glucose. PMID:23349500

Tubular Obstruction Leads to Progressive Proximal Tubular Injury and Atubular Glomeruli in Polycystic Kidney Disease

PubMed Central

Galarreta, Carolina I.; Grantham, Jared J.; Forbes, Michael S.; Maser, Robin L.; Wallace, Darren P.; Chevalier, Robert L.

2015-01-01

In polycystic kidney disease (PKD), renal parenchyma is destroyed by cysts, hypothesized to obstruct nephrons. A signature of unilateral ureteral obstruction, proximal tubular atrophy leads to formation of atubular glomeruli. To determine whether this process occurs in PKD, kidneys from pcy mice (moderately progressive PKD), kidneys from cpk mice (rapidly progressive PKD), and human autosomal dominant PKD were examined in early and late stages. Integrity of the glomerulotubular junction and proximal tubular mass were determined in sections stained with Lotus tetragonolobus lectin. Development of proximal tubular atrophy and atubular glomeruli was determined in serial sections of individual glomeruli. In pcy mice, most glomerulotubular junctions were normal at 20 weeks, but by 30 weeks, 56% were atrophic and 25% of glomeruli were atubular; glomerulotubular junction integrity decreased with increasing cyst area (r = 0.83, P < 0.05). In cpk mice, all glomerulotubular junctions were normal at 10 days, but by 19 days, 26% had become abnormal. In early-stage autosomal dominant PKD kidneys, 50% of glomeruli were atubular or attached to atrophic tubules; in advanced disease, 100% were abnormal. Thus, proximal tubular injury in cystic kidneys closely parallels that observed with ureteral obstruction. These findings support the hypothesis that, in renal cystic disorders, cyst-dependent obstruction of medullary and cortical tubules initiates a process culminating in widespread destruction of proximal convoluted tubules at the glomerulotubular junction. PMID:24815352

Complete secretion of activable bovine prochymosin by genetically engineered L forms of Proteus mirabilis.

PubMed Central

Klessen, C; Schmidt, K H; Gumpert, J; Grosse, H H; Malke, H

1989-01-01

To circumvent problems encountered in the synthesis of active chymosin in a number of bacteria and fungi, a recombinant DNA L-form expression system that directed the complete secretion of fully activable prochymosin into the extracellular culture medium was developed. The expression plasmid constructions involved the in-frame fusion of prochymosin cDNA minus codons 1 to 4 to streptococcal pyrogenic exotoxin type A gene (speA') sequences, including the speA promoter, ribosomal binding site, and signal sequence and five codons of mature SpeA. Secretion of fusion prochymosin enzymatically and immunologically indistinguishable from bovine prochymosin was achieved after transformation of two stable protoplast type L-form strains derived from Proteus mirabilis. The secreted proenzyme was converted by autocatalytic processing to chymosin showing milk-clotting activity. In controlled laboratory fermentation processes, a maximum specific rate of activable prochymosin synthesis of 0.57 x 10(-3)/h was determined from the time courses of biomass dry weight and product formation. Yields as high as 40 +/- 10 micrograms/ml were obtained in the cell-free culture fluid of strain L99 carrying a naturally altered expression plasmid of increased segregational stability. The expression-secretion system described may be generally useful for production of recombinant mammalian proteins synthesized intracellularly as aberrantly folded insoluble aggregates. Images PMID:2499253

Increased renal tubular sodium reabsorption during exercise-induced hypervolemia in humans

NASA Technical Reports Server (NTRS)

Nagashima, K.; Wu, J.; Kavouras, S. A.; Mack, G. W.

2001-01-01

We tested the hypothesis that renal tubular Na(+) reabsorption increased during the first 24 h of exercise-induced plasma volume expansion. Renal function was assessed 1 day after no-exercise control (C) or intermittent cycle ergometer exercise (Ex, 85% of peak O(2) uptake) for 2 h before and 3 h after saline loading (12.5 ml/kg over 30 min) in seven subjects. Ex reduced renal blood flow (p-aminohippurate clearance) compared with C (0.83 +/- 0.12 vs. 1.49 +/- 0.24 l/min, P < 0.05) but did not influence glomerular filtration rates (97 +/- 10 ml/min, inulin clearance). Fractional tubular reabsorption of Na(+) in the proximal tubules was higher in Ex than in C (P < 0.05). Saline loading decreased fractional tubular reabsorption of Na(+) from 99.1 +/- 0.1 to 98.7 +/- 0.1% (P < 0.05) in C but not in Ex (99.3 +/- 0.1 to 99.4 +/- 0.1%). Saline loading reduced plasma renin activity and plasma arginine vasopressin levels in C and Ex, although the magnitude of decrease was greater in C (P < 0.05). These results indicate that, during the acute phase of exercise-induced plasma volume expansion, increased tubular Na(+) reabsorption is directed primarily to the proximal tubules and is associated with a decrease in renal blood flow. In addition, saline infusion caused a smaller reduction in fluid-regulating hormones in Ex. The attenuated volume-regulatory response acts to preserve distal tubular Na(+) reabsorption during saline infusion 24 h after exercise.

Transcription factor Nrf2 hyperactivation in early-phase renal ischemia-reperfusion injury prevents tubular damage progression.

PubMed

Nezu, Masahiro; Souma, Tomokazu; Yu, Lei; Suzuki, Takafumi; Saigusa, Daisuke; Ito, Sadayoshi; Suzuki, Norio; Yamamoto, Masayuki

2017-02-01

Acute kidney injury is a devastating disease with high morbidity in hospitalized patients and contributes to the pathogenesis of chronic kidney disease. An underlying mechanism of acute kidney injury involves ischemia-reperfusion injury which, in turn, induces oxidative stress and provokes organ damage. Nrf2 is a master transcription factor that regulates the cellular response to oxidative stress. Here, we examined the role of Nrf2 in the progression of ischemia-reperfusion injury-induced kidney damage in mice using genetic and pharmacological approaches. Both global and tubular-specific Nrf2 activation enhanced gene expression of antioxidant and NADPH synthesis enzymes, including glucose-6-phosphate dehydrogenase, and ameliorated both the initiation of injury in the outer medulla and the progression of tubular damage in the cortex. Myeloid-specific Nrf2 activation was ineffective. Short-term administration of the Nrf2 inducer CDDO during the initial phase of injury ameliorated the late phase of tubular damage. This inducer effectively protected the human proximal tubular cell line HK-2 from oxidative stress-mediated cell death while glucose-6-phosphate dehydrogenase knockdown increased intracellular reactive oxygen species. These findings demonstrate that tubular hyperactivation of Nrf2 in the initial phase of injury prevents the progression of reactive oxygen species-mediated tubular damage by inducing antioxidant enzymes and NADPH synthesis. Thus, Nrf2 may be a promising therapeutic target for preventing acute kidney injury to chronic kidney disease transition. Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

Cellular Uptake and Localization of Polymyxins in Renal Tubular Cells Using Rationally Designed Fluorescent Probes

PubMed Central

Yun, Bo; Azad, Mohammad A. K.; Nowell, Cameron J.; Nation, Roger L.; Thompson, Philip E.; Roberts, Kade D.

2015-01-01

Polymyxins are cyclic lipopeptide antibiotics that serve as a last line of defense against Gram-negative bacterial superbugs. However, the extensive accumulation of polymyxins in renal tubular cells can lead to nephrotoxicity, which is the major dose-limiting factor in clinical use. In order to gain further insights into the mechanism of polymyxin-induced nephrotoxicity, we have rationally designed novel fluorescent polymyxin probes to examine the localization of polymyxins in rat renal tubular (NRK-52E) cells. Our design strategy focused on incorporating a dansyl fluorophore at the hydrophobic centers of the polymyxin core structure. To this end, four novel regioselectively labeled monodansylated polymyxin B probes (MIPS-9541, MIPS-9542, MIPS-9543, and MIPS-9544) were designed, synthesized, and screened for their antimicrobial activities and apoptotic effects against rat kidney proximal tubular cells. On the basis of the assessment of antimicrobial activities, cellular uptake, and apoptotic effects on renal tubular cells, incorporation of a dansyl fluorophore at either position 6 or 7 (MIPS-9543 and MIPS-9544, respectively) of the polymyxin core structure appears to be an appropriate strategy for generating representative fluorescent polymyxin probes to be utilized in intracellular imaging and mechanistic studies. Furthermore, confocal imaging experiments utilizing these probes showed evidence of partial colocalization of the polymyxins with both the endoplasmic reticulum and mitochondria in rat renal tubular cells. Our results highlight the value of these new fluorescent polymyxin probes and provide further insights into the mechanism of polymyxin-induced nephrotoxicity. PMID:26392495

A tubular flux-switching permanent magnet machine

NASA Astrophysics Data System (ADS)

Wang, J.; Wang, W.; Clark, R.; Atallah, K.; Howe, D.

2008-04-01

The paper describes a novel tubular, three-phase permanent magnet brushless machine, which combines salient features from both switched reluctance and permanent magnet machine technologies. It has no end windings and zero net radial force and offers a high power density and peak force capability, as well as the potential for low manufacturing cost. It is, therefore, eminently suitable for a variety of applications, ranging from free-piston energy converters to active vehicle suspensions.

Tubular structured hierarchical mesoporous titania material derived from natural cellulosic substances and application as photocatalyst for degradation of methylene blue

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

Huang, Haiqing; Liu, Xiaoyan; Huang, Jianguo, E-mail: jghuang@zju.edu.cn

Graphical abstract: Bio-inspired, tubular structured hierarchical mesoporous titania material with high photocatalytic activity under UV light was fabricated employing natural cellulosic substance (cotton) as hard template and cetyltrimethylammonium bromide (CTAB) surfactant as soft template using a one-pot sol-gel method. Highlights: {yields} Tubular structured mesoporous titania material was fabricated by sol-gel method. {yields} The titania material faithfully recorded the hierarchical structure of the template substrate (cotton). {yields} The titania material exhibited high photocatalytic activity in decomposition of methylene blue. -- Abstract: Bio-inspired, tubular structured hierarchical mesoporous titania material was designed and fabricated employing natural cellulosic substance (cotton) as hard template andmore » cetyltrimethylammonium bromide (CTAB) surfactant as soft template by one-pot sol-gel method. The tubular structured hierarchical mesoporous titania material processes large specific surface area (40.23 m{sup 2}/g) and shows high photocatalytic activity in the photodegradation of methylene blue under UV light irradiation.« less

Response of human renal tubular cells to cyclosporine and sirolimus: A toxicogenomic study

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

Pallet, Nicolas; Rabant, Marion; Xu-Dubois, Yi-Chun

The molecular mechanisms involved in the potentially nephrotoxic response of tubular cells to immunosuppressive drugs remain poorly understood. Transcriptional profiles of human proximal tubular cells exposed to cyclosporine A (CsA), sirolimus (SRL) or their combination, were established using oligonucleotide microarrays. Hierarchical clustering of genes implicated in fibrotic processes showed a clear distinction between expression profiles with CsA and CsA + SRL treatments on the one hand and SRL treatment on the other. Functional analysis found that CsA and CsA + SRL treatments preferentially alter biological processes located at the cell membrane, such as ion transport or signal transduction, whereas SRLmore » modifies biological processes within the nucleus and related to transcriptional activity. Genome wide expression analysis suggested that CsA may induce an endoplasmic reticulum (ER) stress in tubular cells in vitro. Moreover we found that CsA exposure in vivo is associated with the upregulation of the ER stress marker BIP in kidney transplant biopsies. In conclusion, this toxicogenomic study highlights the molecular interaction networks that may contribute to the tubular response to CsA and SRL. These results may also offer a new working hypothesis for future research in the field of CsA nephrotoxicity. Further studies are needed to evaluate if ER stress detection in tubular cells in human biopsies can predict CsA nephrotoxicity.« less

Upregulation of TLR4 via PKC activation contributes to impaired wound healing in high-glucose-treated kidney proximal tubular cells.

PubMed

Peng, Jianping; Zheng, Hang; Wang, Xia; Cheng, Zhixiang

2017-01-01

Acute kidney injury (AKI) leads to a worse prognosis in diabetic patients compared with prognoses in non-diabetic patients, but whether and how diabetes affects kidney repair after AKI remains unknown. Here, we used scratch-wound healing and transwell migration models to examine whether and how wound healing is affected by high glucose levels in cultured kidney proximal tubular cells (RPTC). The results show that scratch-wound healing and transwell migration were significantly slower in high-glucose-treated kidney tubular cells (30 mM glucose) than in low-glucose-treated cells (5.5 mM). Toll-like receptor 4 (TLR4), MyD88, phospho-protein kinase C (PKC), phospho-p38 MAPK and monocyte chemoattractant protein-1 (MCP-1) mRNA levels were upregulated after high glucose treatments. Staurosporine, a selective PKC inhibitor, inhibited TLR4, MyD88 and p-p38 upregulation in the high-glucose-treated cells, indicating the involvement of PKC in high-glucose-induced TLR4 upregulation. The pharmacological inhibition of TLR4 or shRNA-mediated TLR4 knockdown improved wound healing and transwell migration in high-glucose-treated RPTC. In contrast, the overexpression of TLR4 in low-glucose-treated RPTC suppressed wound healing, mimicking the effects of high glucose levels. These results suggest that the upregulation of TLR4 expression via PKC activation contributes to defective wound healing in high-glucose-treated kidney tubular cells.

Upregulation of TLR4 via PKC activation contributes to impaired wound healing in high-glucose-treated kidney proximal tubular cells

PubMed Central

Peng, Jianping; Zheng, Hang; Wang, Xia; Cheng, Zhixiang

2017-01-01

Acute kidney injury (AKI) leads to a worse prognosis in diabetic patients compared with prognoses in non-diabetic patients, but whether and how diabetes affects kidney repair after AKI remains unknown. Here, we used scratch-wound healing and transwell migration models to examine whether and how wound healing is affected by high glucose levels in cultured kidney proximal tubular cells (RPTC). The results show that scratch-wound healing and transwell migration were significantly slower in high-glucose-treated kidney tubular cells (30 mM glucose) than in low-glucose-treated cells (5.5 mM). Toll-like receptor 4 (TLR4), MyD88, phospho-protein kinase C (PKC), phospho-p38 MAPK and monocyte chemoattractant protein-1 (MCP-1) mRNA levels were upregulated after high glucose treatments. Staurosporine, a selective PKC inhibitor, inhibited TLR4, MyD88 and p-p38 upregulation in the high-glucose-treated cells, indicating the involvement of PKC in high-glucose-induced TLR4 upregulation. The pharmacological inhibition of TLR4 or shRNA-mediated TLR4 knockdown improved wound healing and transwell migration in high-glucose-treated RPTC. In contrast, the overexpression of TLR4 in low-glucose-treated RPTC suppressed wound healing, mimicking the effects of high glucose levels. These results suggest that the upregulation of TLR4 expression via PKC activation contributes to defective wound healing in high-glucose-treated kidney tubular cells. PMID:28542370

Human mesenchymal stromal cells transplanted into mice stimulate renal tubular cells and enhance mitochondrial function.

PubMed

Perico, Luca; Morigi, Marina; Rota, Cinzia; Breno, Matteo; Mele, Caterina; Noris, Marina; Introna, Martino; Capelli, Chiara; Longaretti, Lorena; Rottoli, Daniela; Conti, Sara; Corna, Daniela; Remuzzi, Giuseppe; Benigni, Ariela

2017-10-17

Mesenchymal stromal cells (MSCs) are renoprotective and drive regeneration following injury, although cellular targets of such an effect are still ill-defined. Here, we show that human umbilical cord (UC)-MSCs transplanted into mice stimulate tubular cells to regain mitochondrial mass and function, associated with enhanced microtubule-rich projections that appear to mediate mitochondrial trafficking to create a reparative dialogue among adjacent tubular cells. Treatment with UC-MSCs in mice with cisplatin-induced acute kidney injury (AKI) regulates mitochondrial biogenesis in proximal tubuli by enhancing PGC1α expression, NAD + biosynthesis and Sirtuin 3 (SIRT3) activity, thus fostering antioxidant defenses and ATP production. The functional role of SIRT3 in tubular recovery is highlighted by data that in SIRT3-deficient mice with AKI, UC-MSC treatment fails to induce renoprotection. These data document a previously unrecognized mechanism through which UC-MSCs facilitate renal repair, so as to induce global metabolic reprogramming of damaged tubular cells to sustain energy supply.Mesenchymal stromal cells drive renal regeneration following injury. Here, the authors show that human mesenchymal stromal cells, when transplanted into mice with acute kidney injury, stimulate renal tubular cell growth and enhance mitochondrial function via SIRT3.

Immunity in the Vagina (Part II): Anti-HIV Activity and Antiviral Content of Human Vaginal Secretions

PubMed Central

Patel, Mickey V.; Ghosh, Mimi; Fahey, John V.; Ochsenbauer, Christina; Rossoll, Richard M.; Wira, Charles R.

2015-01-01

Problem Whether the concentrations of antiviral proteins, and anti-HIV activity, within human vaginal secretions changes across the menstrual cycle is unknown. Method of Study Using a menstrual cup, vaginal secretions from premenopausal women were recovered at the proliferative (d6–8), mid-cycle (d13–15) and secretory (d21–23) stages of the menstrual cycle. Antiviral protein concentration was determined by ELISA, and anti-HIV activity assessed using the TZM-bl reporter cell line. Results CCL20, RANTES, elafin, HBD2, SDF-1α and IL-8 levels were detectable in the secretions. Vaginal secretions had anti-HIV activity against specific clade B strains of HIV, with significant inhibition of IIIB and increased infectivity of transmitted/founder CH077.t. No significant differences in either antiviral protein concentration or anti-HIV activity with respect to menstrual cycle stage were measured, but marked differences were observed in both parameters over the course of the cycle between different women, and in consecutive cycles from the same woman. Conclusion The vagina contains a complement of antiviral proteins. The variation in anti-HIV activity demonstrates that immune protection in the vagina is not constant. Intra- and inter-individual variations suggest that factors in addition to sex hormones influence antiviral protection. Lastly, the menstrual cup is a new model for recovering undiluted vaginal secretions from women throughout their reproductive life. PMID:24806967

Early to Late Endosome Trafficking Controls Secretion and Zymogen Activation in Rodent and Human Pancreatic Acinar Cells.

PubMed

Messenger, Scott W; Thomas, Diana Dh; Cooley, Michelle M; Jones, Elaina K; Falkowski, Michelle A; August, Benjamin K; Fernandez, Luis A; Gorelick, Fred S; Groblewski, Guy E

2015-11-01

Pancreatic acinar cells have an expanded apical endosomal system, the physiological and pathophysiological significance of which is still emerging. Phosphatidylinositol-3,5-bisphosphate (PI(3,5)P 2 ) is an essential phospholipid generated by PIKfyve, which phosphorylates phosphatidylinositol-3-phosphate (PI(3)P). PI(3,5)P 2 is necessary for maturation of early endosomes (EE) to late endosomes (LE). Inhibition of EE to LE trafficking enhances anterograde endosomal trafficking and secretion at the plasma membrane by default through a recycling endosome (RE) intermediate. We assessed the effects of modulating PIKfyve activity on apical trafficking and pancreatitis responses in pancreatic acinar cells. Inhibition of EE to LE trafficking was achieved using pharmacological inhibitors of PIKfyve, expression of dominant negative PIKfyve K1877E, or constitutively active Rab5-GTP Q79L. Anterograde endosomal trafficking was manipulated by expression of constitutively active and dominant negative Rab11a mutants. The effects of these agents on secretion, endolysosomal exocytosis of lysosome associated membrane protein (LAMP1), and trypsinogen activation in response to high-dose CCK-8, bile acids and cigarette toxin was determined. PIKfyve inhibition increased basal and stimulated secretion. Adenoviral overexpression of PIKfyve decreased secretion leading to cellular death. Expression of Rab5-GTP Q79L or Rab11a-GTP Q70L enhanced secretion. Conversely, dominant-negative Rab11a-GDP S25N reduced secretion. High-dose CCK inhibited endolysosomal exocytosis that was reversed by PIKfyve inhibition. PIKfyve inhibition blocked intracellular trypsin accumulation and cellular damage responses to high CCK-8, tobacco toxin, and bile salts in both rodent and human acini. These data demonstrate that EE-LE trafficking acutely controls acinar secretion and the intracellular activation of zymogens leading to the pathogenicity of acute pancreatitis.

Cellular Uptake and Localization of Polymyxins in Renal Tubular Cells Using Rationally Designed Fluorescent Probes.

PubMed

Yun, Bo; Azad, Mohammad A K; Nowell, Cameron J; Nation, Roger L; Thompson, Philip E; Roberts, Kade D; Velkov, Tony; Li, Jian

2015-12-01

Polymyxins are cyclic lipopeptide antibiotics that serve as a last line of defense against Gram-negative bacterial superbugs. However, the extensive accumulation of polymyxins in renal tubular cells can lead to nephrotoxicity, which is the major dose-limiting factor in clinical use. In order to gain further insights into the mechanism of polymyxin-induced nephrotoxicity, we have rationally designed novel fluorescent polymyxin probes to examine the localization of polymyxins in rat renal tubular (NRK-52E) cells. Our design strategy focused on incorporating a dansyl fluorophore at the hydrophobic centers of the polymyxin core structure. To this end, four novel regioselectively labeled monodansylated polymyxin B probes (MIPS-9541, MIPS-9542, MIPS-9543, and MIPS-9544) were designed, synthesized, and screened for their antimicrobial activities and apoptotic effects against rat kidney proximal tubular cells. On the basis of the assessment of antimicrobial activities, cellular uptake, and apoptotic effects on renal tubular cells, incorporation of a dansyl fluorophore at either position 6 or 7 (MIPS-9543 and MIPS-9544, respectively) of the polymyxin core structure appears to be an appropriate strategy for generating representative fluorescent polymyxin probes to be utilized in intracellular imaging and mechanistic studies. Furthermore, confocal imaging experiments utilizing these probes showed evidence of partial colocalization of the polymyxins with both the endoplasmic reticulum and mitochondria in rat renal tubular cells. Our results highlight the value of these new fluorescent polymyxin probes and provide further insights into the mechanism of polymyxin-induced nephrotoxicity. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Autophagy inhibition attenuates hyperoxaluria-induced renal tubular oxidative injury and calcium oxalate crystal depositions in the rat kidney.

PubMed

Duan, Xiaolu; Kong, Zhenzhen; Mai, Xin; Lan, Yu; Liu, Yang; Yang, Zhou; Zhao, Zhijian; Deng, Tuo; Zeng, Tao; Cai, Chao; Li, Shujue; Zhong, Wen; Wu, Wenqi; Zeng, Guohua

2018-06-01

Hyperoxaluria-induced oxidative injury of renal tubular epithelial cell is a casual and essential factor in kidney calcium oxalate (CaOx) stone formation. Autophagy has been shown to be critical for the regulation of oxidative stress-induced renal tubular injury; however, little is known about its role in kidney CaOx stone formation. In the present study, we found that the autophagy antagonist chloroquine could significantly attenuate oxalate-induced autophagy activation, oxidative injury and mitochondrial damage of renal tubular cells in vitro and in vivo, as well as hyperoxaluria-induced CaOx crystals depositions in rat kidney, whereas the autophagy agonist rapamycin exerted contrasting effects. In addition, oxalate-induced p38 phosphorylation was significantly attenuated by chloroquine pretreatment but was markedly enhanced by rapamycin pretreatment, whereas the protective effect of chloroquine on rat renal tubular cell oxidative injury was partly reversed by a p38 protein kinase activator anisomycin. Furthermore, the knockdown of Beclin1 represented similar effects to chloroquine on oxalate-induced cell oxidative injury and p38 phosphorylation in vitro. Taken together, our results revealed that autophagy inhibition could attenuate oxalate-induced oxidative injury of renal tubular cell and CaOx crystal depositions in the rat kidney via, at least in part, inhibiting the activation of p38 signaling pathway, thus representing a novel role of autophagy in the regulation of oxalate-induced renal oxidative injury and CaOx crystal depositions for the first time. Copyright © 2018. Published by Elsevier B.V.

Innate immunity in the vagina (Part II): Anti-HIV activity and antiviral content of human vaginal secretions.

PubMed

Patel, Mickey V; Ghosh, Mimi; Fahey, John V; Ochsenbauer, Christina; Rossoll, Richard M; Wira, Charles R

2014-07-01

Whether the concentrations of antiviral proteins, and anti-HIV activity, within human vaginal secretions change across the menstrual cycle is unknown. Using a menstrual cup, vaginal secretions from pre-menopausal women were recovered at the proliferative (d6-8), mid-cycle (d13-15), and secretory (d21-23) stages of the menstrual cycle. Antiviral protein concentration was determined by ELISA, and anti-HIV activity assessed using the TZM-bl reporter cell line. CCL20, RANTES, elafin, HBD2, SDF-1α, and IL-8 levels were detectable in the secretions. Vaginal secretions had anti-HIV activity against specific clade B strains of HIV, with significant inhibition of IIIB and increased infectivity of transmitted/founder CH077.t. No significant differences in either antiviral protein concentration or anti-HIV activity with respect to menstrual cycle stage were measured, but marked differences were observed in both parameters over the course of the cycle between different women and in consecutive cycles from the same woman. The vagina contains a complement of antiviral proteins. The variation in anti-HIV activity demonstrates that immune protection in the vagina is not constant. Intra- and interindividual variations suggest that factors in addition to sex hormones influence antiviral protection. Lastly, the menstrual cup is a new model for recovering undiluted vaginal secretions from women throughout their reproductive life. © 2014 John Wiley & Sons Ltd.

Three-Dimensional Tubular MoS2/PANI Hybrid Electrode for High Rate Performance Supercapacitor.

PubMed

Ren, Lijun; Zhang, Gaini; Yan, Zhe; Kang, Liping; Xu, Hua; Shi, Feng; Lei, Zhibin; Liu, Zong-Huai

2015-12-30

By using three-dimensional (3D) tubular molybdenum disulfide (MoS2) as both an active material in electrochemical reaction and a framework to provide more paths for insertion and extraction of ions, PANI nanowire arrays with a diameter of 10-20 nm can be controllably grown on both the external and internal surface of 3D tubular MoS2 by in situ oxidative polymerization of aniline monomers and 3D tubular MoS2/PANI hybrid materials with different amounts of PANI are prepared. A controllable growth of PANI nanowire arrays on the tubular MoS2 surface provides an opportunity to optimize the capacitive performance of the obtained electrodes. When the loading amount of PANI is 60%, the obtained MoS2/PANI-60 hybrid electrode not only shows a high specific capacitance of 552 F/g at a current density of 0.5 A/g, but also gives excellent rate capability of 82% from 0.5 to 30 A/g. The remarkable rate performance can be mainly attributed to the architecture with synergistic effect between 3D tubular MoS2 and PANI nanowire arrays. Moreover, the MoS2/PANI-60 based symmetric supercapacitor also exhibits the excellent rate performance and good cycling stability. The specific capacitance based on the total mass of the two electrodes is 124 F/g at a current density of 1 A/g and 79% of its initial capacitance is remained after 6000 cycles. The 3D tubular structure provides a good and favorable method for improving the capacitance retention of PANI electrode.

Design of a tubular skylight system

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

Chao, B.L.

1996-10-01

Since its introduction to the US market in 1991, tubular skylight provides a solution to the problem of lighting up dark corners in a house. Over the years, design of similar products has emphasized on quantity alone and attention to a range of other equally important issues: efficient collecting system, selection of higher specular reflectance material, seals, distribution and quality of light, was not noted. In this paper, the fundamental design concept of an efficient tubular skylight and the possibility of collimating diffuse light is reviewed. The importance of specular reflectance of the tube material on the performance of tubularmore » skylight is demonstrated. Visual appearance (quality) of transmitted light down the tube is related in part to the yellowness index of various materials. Discussion of adequacy of current building and energy code requirements on tubular skylights is briefly touched on and energy simulation results based on a numerical code are presented.« less

Proximal tubular secretion of creatinine by organic cation transporter OCT2 in cancer patients.

PubMed

Ciarimboli, Giuliano; Lancaster, Cynthia S; Schlatter, Eberhard; Franke, Ryan M; Sprowl, Jason A; Pavenstädt, Hermann; Massmann, Vivian; Guckel, Denise; Mathijssen, Ron H J; Yang, Wenjian; Pui, Ching-Hon; Relling, Mary V; Herrmann, Edwin; Sparreboom, Alex

2012-02-15

Knowledge of transporters responsible for the renal secretion of creatinine is key to a proper interpretation of serum creatinine and/or creatinine clearance as markers of renal function in cancer patients receiving chemotherapeutic agents. Creatinine transport was studied in transfected HEK293 cells in vitro and in wild-type mice and age-matched organic cation transporter 1 and 2-deficient [Oct1/2(-/-)] mice ex vivo and in vivo. Clinical pharmacogenetic and transport inhibition studies were done in two separate cohorts of cancer patients. Compared with wild-type mice, creatinine clearance was significantly impaired in Oct1/2(-/-) mice. Furthermore, creatinine inhibited organic cation transport in freshly isolated proximal tubules from wild-type mice and humans, but not in those from Oct1/2(-/-) mice. In a genetic association analysis (n = 590), several polymorphisms around the OCT2/SLC22A2 gene locus, including rs2504954 (P = 0.000873), were significantly associated with age-adjusted creatinine levels. Furthermore, in cancer patients (n = 68), the OCT2 substrate cisplatin caused an acute elevation of serum creatinine (P = 0.0083), consistent with inhibition of an elimination pathway. Collectively, this study shows that OCT2 plays a decisive role in the renal secretion of creatinine. This process can be inhibited by OCT2 substrates, which impair the usefulness of creatinine as a marker of renal function. ©2012 AACR.

Secreted and Transmembrane Wnt Inhibitors and Activators

PubMed Central

Cruciat, Cristina-Maria; Niehrs, Christof

2013-01-01

Signaling by the Wnt family of secreted glycoproteins plays important roles in embryonic development and adult homeostasis. Wnt signaling is modulated by a number of evolutionarily conserved inhibitors and activators. Wnt inhibitors belong to small protein families, including sFRP, Dkk, WIF, Wise/SOST, Cerberus, IGFBP, Shisa, Waif1, APCDD1, and Tiki1. Their common feature is to antagonize Wnt signaling by preventing ligand–receptor interactions or Wnt receptor maturation. Conversely, the Wnt activators, R-spondin and Norrin, promote Wnt signaling by binding to Wnt receptors or releasing a Wnt-inhibitory step. With few exceptions, these antagonists and agonists are not pure Wnt modulators, but also affect additional signaling pathways, such as TGF-β and FGF signaling. Here we discuss their interactions with Wnt ligands and Wnt receptors, their role in developmental processes, as well as their implication in disease. PMID:23085770

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

Albumin-induced apoptosis of tubular cells is modulated by BASP1

PubMed Central

Sanchez-Niño, M D; Fernandez-Fernandez, B; Perez-Gomez, M V; Poveda, J; Sanz, A B; Cannata-Ortiz, P; Ruiz-Ortega, M; Egido, J; Selgas, R; Ortiz, A

2015-01-01

Albuminuria promotes tubular injury and cell death, and is associated with faster progression of chronic kidney disease (CKD) to end-stage renal disease. However, the molecular mechanisms regulating tubular cell death in response to albuminuria are not fully understood. Brain abundant signal protein 1 (BASP1) was recently shown to mediate glucose-induced apoptosis in tubular cells. We have studied the role of BASP1 in albumin-induced tubular cell death. BASP1 expression was studied in experimental puromycin aminonucleoside-induced nephrotic syndrome in rats and in human nephrotic syndrome. The role of BASP1 in albumin-induced apoptosis was studied in cultured human HK2 proximal tubular epithelial cells. Puromycin aminonucleoside induced proteinuria and increased total kidney BASP1 mRNA and protein expression. Immunohistochemistry localized the increased BASP1 to tubular cells. BASP1 expression colocalized with deoxynucleotidyl-transferase-mediated dUTP nick-end labeling staining for apoptotic cells. Increased tubular BASP1 expression was observed in human proteinuric nephropathy by immunohistochemistry, providing evidence for potential clinical relevance. In cultured tubular cells, albumin induced apoptosis and increased BASP1 mRNA and protein expression at 6–48 h. Confocal microscopy localized the increased BASP1 expression in albumin-treated cells mainly to the perinuclear area. A peripheral location near the cell membrane was more conspicuous in albumin-treated apoptotic cells, where it colocalized with actin. Inhibition of BASP1 expression by a BASP1 siRNA protected from albumin-induced apoptosis. In conclusion, albumin-induced apoptosis in tubular cells is BASP1-dependent. This information may be used to design novel therapeutic approaches to slow CKD progression based on protection of tubular cells from the adverse consequences of albuminuria. PMID:25675304

75 FR 28058 - Certain Oil Country Tubular Goods From China; Determination

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-19

... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-1159 (Final)] Certain Oil Country Tubular... threatened with material injury by reason of imports from China of certain oil country tubular goods (``OCTG... are contained in USITC Publication 4152 (May 2010), entitled Certain Oil Country Tubular Goods From...

Tubular duplication of the oesophagus presenting with dysphagia.

PubMed

Saha, A K; Kundu, A K

2014-06-01

Duplications of the alimentary tract are rare congenital malformations, with the ileum being the most commonly affected site, followed by the oesophagus. Among oesophageal duplications, cystic duplication is the most common and the tubular variety, the rarest. Herein, we report a rare case of tubular oesophageal duplication, complicated by adenosquamous carcinoma at the lower end of the oesophagus, in a 32-year-old man who presented with progressive dysphagia. Although proton pump inhibitors may relieve dysphagia, oesophagectomy and gastric interpositioning should be the first-line treatment for patients with tubular oesophageal duplication, in order to reduce the risk of malignant transformation at the lower end of the oesophagus.

Protective effect of 20-hydroxyeicosatetraenoic acid (20-HETE) on adriamycin-induced toxicity of human renal tubular epithelial cell (HK-2).

PubMed

Tian, Ting; Li, Jin; Wang, Meng-Ying; Xie, Xian-Fei; Li, Qi-Xiong

2012-05-15

20-Hydroxyeicosatetraenoic acid is a cytochrome P4504A11 metabolite of arachidonic acid that plays an important role in the regulation of human renal functions. In the present study, we investigated the role of 20-hydroxyeicosatetraenoic acid on adriamycin induced toxicity in human renal tubular epithelial cells. Results showed that cell viability was decreased significantly and lactate dehydrogenase activity was increased significantly in a concentration-dependent manner when human renal tubular epithelial cells were incubated with adriamycin (10⁻⁷-10⁻³ mol/l) for 24h. In contrast, 20-hydroxyeicosatetraenoic acid (0.1, 1, 10, 50 μmol/l) increased cell survival and decreased lactate dehydrogenase activity concentration dependently in human renal tubular epithelial cells. When 20-hydroxyeicosatetraenoic acid (10, 50 μmol/l) was co-administered with adriamycin (10⁻³ mol/l), it significantly increased cell viability and decreased lactate dehydrogenase activity. On the other hand, N-hydroxy-N'-(4-butyl-2-methylphenyl)formamidine (HET-0016) (1 μM), a selective inhibitor of 20-hydroxyeicosatetraenoic acid synthesizing enzyme exaggerated cell viability reduction and lactate dehydrogenase activity augmentation induced by adriamycin. Adriamycin suppressed the expression of cytochrome P4504A11 gene and its protein production in human renal tubular epithelial cells. Furthermore, adriamycin was more effective than N-hydroxy-N'-(4-butyl-2-methylphenyl)formamidine at lowering the expression of cytochrome P4504A11 gene and its protein. These results suggest that 20-hydroxyeicosatetraenoic acid may protect adriamycin-induced toxicity of human renal tubular epithelial cells, meanwhile, adriamycin-induced toxicity of human renal tubular epithelial cells possibly involves inhibiting cytochrome P4504A11 expression. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

Mars Life? - Microscopic Tubular Structures

NASA Technical Reports Server (NTRS)

1996-01-01

This electron microscope image shows tubular structures of likely Martian origin. These structures are very similar in size and shape to extremely tiny microfossils found in some Earth rocks. This photograph is part of a report by a NASA research team published in the Aug. 16, 1996, issue of the journal Science. A two-year investigation by the team found organic molecules, mineral features characteristic of biological activity and possible microscopic fossils such as these inside of an ancient Martian rock that fell to Earth as a meteorite. The largest possible fossils are less than 1/100th the diameter of a human hair in size while most are ten times smaller.

Proximal Tubular Secretion of Creatinine by Organic Cation Transporter OCT2 in Cancer Patients

PubMed Central

Ciarimboli, Giuliano; Lancaster, Cynthia S.; Schlatter, Eberhard; Franke, Ryan M.; Sprowl, Jason A.; Pavenstädt, Hermann; Massmann, Vivian; Guckel, Denise; Mathijssen, Ron H. J.; Yang, Wenjian; Pui, Ching-Hon; Relling, Mary V.; Herrmann, Edwin; Sparreboom, Alex

2012-01-01

Purpose Knowledge of transporters responsible for the renal secretion of creatinine is key to a proper interpretation of serum creatinine and/or creatinine clearance as markers of renal function in cancer patients receiving chemotherapeutic agents. Experimental Design Creatinine transport was studied in transfected HEK293 cells in vitro and in wildtype mice and age-matched organic cation transporter 1 and 2-deficient [Oct1/2(−/−)] mice ex vivo and in vivo. Clinical pharmacogenetic and transport inhibition studies were done in two separate cohorts of cancer patients. Results Compared to wildtype mice, creatinine clearance was significantly impaired in Oct1/2(−/−) mice. Furthermore, creatinine inhibited organic cation transport in freshly-isolated proximal tubules from wild-type mice and humans, but not in those from Oct1/2(−/−) mice. In a genetic-association analysis (n=590), several polymorphisms around the OCT2/SLC22A2 gene locus, including rs2504954 (P=0.000873), were significantly associated with age-adjusted creatinine levels. Furthermore, in cancer patients (n=68), the OCT2 substrate cisplatin caused an acute elevation of serum creatinine (P=0.0083), consistent with inhibition of an elimination pathway. Conclusions Collectively, this study shows that OCT2 plays a decisive role in the renal secretion of creatinine. This process can be inhibited by OCT2 substrates, which impair the usefulness of creatinine as a marker of renal function. PMID:22223530

Activation of the Farnesoid X Receptor Induces Hepatic Expression and Secretion of Fibroblast Growth Factor 21*

PubMed Central

Cyphert, Holly A.; Ge, Xuemei; Kohan, Alison B.; Salati, Lisa M.; Zhang, Yanqiao; Hillgartner, F. Bradley

2012-01-01

Previous studies have shown that starvation or consumption of a high fat, low carbohydrate (HF-LC) ketogenic diet induces hepatic fibroblast growth factor 21 (FGF21) gene expression in part by activating the peroxisome proliferator-activated receptor-α (PPARα). Using primary hepatocyte cultures to screen for endogenous signals that mediate the nutritional regulation of FGF21 expression, we identified two sources of PPARα activators (i.e. nonesterified unsaturated fatty acids and chylomicron remnants) that induced FGF21 gene expression. In addition, we discovered that natural (i.e. bile acids) and synthetic (i.e. GW4064) activators of the farnesoid X receptor (FXR) increased FGF21 gene expression and secretion. The effects of bile acids were additive with the effects of nonesterified unsaturated fatty acids in regulating FGF21 expression. FXR activation of FGF21 gene transcription was mediated by an FXR/retinoid X receptor binding site in the 5′-flanking region of the FGF21 gene. FGF19, a gut hormone whose expression and secretion is induced by intestinal bile acids, also increased hepatic FGF21 secretion. Deletion of FXR in mice suppressed the ability of an HF-LC ketogenic diet to induce hepatic FGF21 gene expression. The results of this study identify FXR as a new signaling pathway activating FGF21 expression and provide evidence that FXR activators work in combination with PPARα activators to mediate the stimulatory effect of an HF-LC ketogenic diet on FGF21 expression. We propose that the enhanced enterohepatic flux of bile acids during HF-LC consumption leads to activation of hepatic FXR and FGF19 signaling activity and an increase in FGF21 gene expression and secretion. PMID:22661717

Kidney specific protein-positive cells derived from embryonic stem cells reproduce tubular structures in vitro and differentiate into renal tubular cells.

PubMed

Morizane, Ryuji; Monkawa, Toshiaki; Fujii, Shizuka; Yamaguchi, Shintaro; Homma, Koichiro; Matsuzaki, Yumi; Okano, Hideyuki; Itoh, Hiroshi

2014-01-01

Embryonic stem cells and induced pluripotent stem cells have the ability to differentiate into various organs and tissues, and are regarded as new tools for the elucidation of disease mechanisms as well as sources for regenerative therapies. However, a method of inducing organ-specific cells from pluripotent stem cells is urgently needed. Although many scientists have been developing methods to induce various organ-specific cells from pluripotent stem cells, renal lineage cells have yet to be induced in vitro because of the complexity of kidney structures and the diversity of kidney-component cells. Here, we describe a method of inducing renal tubular cells from mouse embryonic stem cells via the cell purification of kidney specific protein (KSP)-positive cells using an anti-KSP antibody. The global gene expression profiles of KSP-positive cells derived from ES cells exhibited characteristics similar to those of cells in the developing kidney, and KSP-positive cells had the capacity to form tubular structures resembling renal tubular cells when grown in a 3D culture in Matrigel. Moreover, our results indicated that KSP-positive cells acquired the characteristics of each segment of renal tubular cells through tubular formation when stimulated with Wnt4. This method is an important step toward kidney disease research using pluripotent stem cells, and the development of kidney regeneration therapies.

Distal renal tubular acidosis and hepatic lipidosis in a cat.

PubMed

Brown, S A; Spyridakis, L K; Crowell, W A

1986-11-15

Clinical and laboratory evidence of hepatic failure was found in a chronically anorectic cat. Simultaneous blood and urine pH determinations established a diagnosis of distal renal tubular acidosis. The cat did not respond to treatment. Necropsy revealed distal tubular nephrosis and hepatic lipidosis. The finding of distal renal tubular acidosis in a cat with hepatic lipidosis emphasizes the importance of complete evaluation of acid-base disorders in patients.

Antibacterial, modulatory activity of antibiotics and toxicity from Rhinella jimi (Stevaux, 2002) (Anura: Bufonidae) glandular secretions.

PubMed

Sales, Débora Lima; Morais-Braga, Maria Flaviana Bezerra; Santos, Antonia Thassya Lucas Dos; Machado, Antonio Judson Targino; Araujo Filho, João Antonio de; Dias, Diógenes de Queiroz; Cunha, Francisco Assis Bezerra da; Saraiva, Rogério de Aquino; Menezes, Irwin Rose Alencar de; Coutinho, Henrique Douglas Melo; Costa, José Galberto Martins; Ferreira, Felipe Silva; Alves, Rômulo Romeu da Nóbrega; Almeida, Waltécio de Oliveira

2017-08-01

The increase in microorganisms with resistance to medications has caused a strong preoccupation within the medical and scientific community. Animal toxins studies, such as parotoid glandular secretions from amphibians, possesses a great potential in the development of drugs, such as antimicrobials, as these possess bioactive compounds. It was evaluated Rhinella jimi (Stevaux, 2002) glandular secretions against standard and multi-resistant bacterial strains; the effect of secretions combined with drugs; and determined the toxicity using two biologic in vivo models, and a in vitro model with mice livers. Standard strains were used for the determination of the Minimum Inhibitory Concentration (MIC), while for the modulatory activity of antibiotics, the clinical isolates Escherichia coli 06, Pseudomonas aeruginosa 03 and Staphylococcus aureus 10 were used. Modulatory activity was evaluated by the broth microdilution method with aminoglycosides and β-lactams as target antibiotics. The secretions in association with the antibiotics have a significant reduction in MIC, both the aminoglycosides and β-lactams. The toxicity and cytotoxicity results were lower than the values used in the modulation. R. jimi glandular secretions demonstrated clinically relevant results regarding the modulation of the tested antimicrobials. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Tubular fluoropolymer arrays with high piezoelectric response

NASA Astrophysics Data System (ADS)

Zhukov, Sergey; Eder-Goy, Dagmar; Biethan, Corinna; Fedosov, Sergey; Xu, Bai-Xiang; von Seggern, Heinz

2018-01-01

Polymers with electrically charged internal air cavities called ferroelectrets exhibit a pronounced piezoelectric effect and are regarded as soft functional materials suitable for sensor and actuator applications. In this work, a simple method for fabricating piezoelectret arrays with open-tubular channels is introduced. A set of individual fluoroethylenepropylene (FEP) tubes is compressed between two heated metal plates. The squeezed FEP tubes are melted together at +270 °C. The resulting structure is a uniform, multi-tubular, flat array that reveals a strong piezoelectric response after a poling step. The fabricated arrays have a high ratio between piezoelectrically active and non-active areas. The optimal charging voltage and stability of the piezoelectric coefficients with pressures and frequency were experimentally investigated for two specific array structures with wall thickness of 50 and 120 μm. The array fabricated from 50 μm thick FEP tubes reveals a stable and high piezoelectric coefficient of {d}33 = 120-160 pC N-1 with a flat frequency response between 0.1 Hz and 10 kHz for pressures between 1 and 100 kPa. An increase of wall thickness to 120 μm is accompanied by a more than twofold decrease in the piezoelectric coefficient as a result of a simultaneously higher effective array stiffness and lower remanent polarization. The obtained experimental results can be used to optimize the array design with regard to the electromechanical performance.

Tubular collagen scaffolds with radial elasticity for hollow organ regeneration.

PubMed

Versteegden, Luuk R; van Kampen, Kenny A; Janke, Heinz P; Tiemessen, Dorien M; Hoogenkamp, Henk R; Hafmans, Theo G; Roozen, Edwin A; Lomme, Roger M; van Goor, Harry; Oosterwijk, Egbert; Feitz, Wout F; van Kuppevelt, Toin H; Daamen, Willeke F

2017-04-01

Tubular collagen scaffolds have been used for the repair of damaged hollow organs in regenerative medicine, but they generally lack the ability to reversibly expand in radial direction, a physiological characteristic seen in many native tubular organs. In this study, tubular collagen scaffolds were prepared that display a shape recovery effect and therefore exhibit radial elasticity. Scaffolds were constructed by compression of fibrillar collagen around a star-shaped mandrel, mimicking folds in a lumen, a typical characteristic of empty tubular hollow organs, such as ureter or urethra. Shape recovery effect was introduced by in situ fixation using a star-shaped mandrel, 3D-printed clamps and cytocompatible carbodiimide crosslinking. Prepared scaffolds expanded upon increase of luminal pressure and closed to the star-shaped conformation after removal of pressure. In this study, we applied this method to construct a scaffold mimicking the dynamics of human urethra. Radial expansion and closure of the scaffold could be iteratively performed for at least 1000 cycles, burst pressure being 132±22mmHg. Scaffolds were seeded with human epithelial cells and cultured in a bioreactor under dynamic conditions mimicking urination (pulse flow of 21s every 2h). Cells adhered and formed a closed luminal layer that resisted flow conditions. In conclusion, a new type of a tubular collagen scaffold has been constructed with radial elastic-like characteristics based on the shape of the scaffold, and enabling the scaffold to reversibly expand upon increase in luminal pressure. These scaffolds may be useful for regenerative medicine of tubular organs. In this paper, a new type I collagen-based tubular scaffold is presented that possesses intrinsic radial elasticity. This characteristic is key to the functioning of a number of tubular organs including blood vessels and organs of the gastrointestinal and urogenital tract. The scaffold was given a star-shaped lumen by physical compression

Circulating anti-double-stranded DNA antibody-secreting cells in patients with systemic lupus erythematosus: a novel biomarker for disease activity.

PubMed

Hanaoka, H; Okazaki, Y; Satoh, T; Kaneko, Y; Yasuoka, H; Seta, N; Kuwana, M

2012-10-01

Antibodies against double-stranded DNA (dsDNA) are widely used to diagnose systemic lupus erythematosus (SLE) and evaluate its activity in patients. This study was undertaken to examine the clinical utility of circulating anti-dsDNA antibody-secreting cells for evaluating SLE patients. Anti-dsDNA antibody-secreting cells quantified using an enzyme-linked immunospot assay were detected in the spleen, bone marrow and peripheral blood from MRL/lpr but not in control BALB/c mice. Circulating anti-dsDNA antibody-secreting cells were detected in 29 (22%) of 130 patients with SLE, but in none of 49 with non-SLE connective-tissue disease or 18 healthy controls. The presence of circulating anti-dsDNA antibody-secreting cells was associated with persistent proteinuria, high SLE disease activity index and systemic lupus activity measures, and a high serum anti-dsDNA antibody titre measured with an enzyme-linked immunosorbent assay. The positive predictive value for active disease was 48% for circulating anti-dsDNA antibody-secreting cells versus 17% for serum anti-dsDNA antibodies. A prospective cohort of patients with circulating anti-dsDNA antibodies and inactive SLE showed that the cumulative disease flare-free rate was significantly lower in patients with than without circulating anti-dsDNA antibody-secreting cells (p < 0.001). Circulating anti-dsDNA antibody-secreting cells are a useful biomarker for assessing disease activity in SLE patients.

Expression of a functional asialoglycoprotein receptor in human renal proximal tubular epithelial cells.

PubMed

Seow, Ying-ying T; Tan, Michelle G K; Woo, Keng Thye

2002-07-01

The asialoglycoprotein receptor (ASGPR) is a C lectin which binds and endocytoses serum glycoproteins. In humans, the ASGPR is shown mainly to occur in hepatocytes, but does occur extrahepatically in thyroid, in small and large intestines, and in the testis. In the kidney, there has been evidence both for and against its existence in mesangial cells. Standard light microscopy examination of renal tissue stained with an antibody against the ASGPR was performed. The mRNA expression for the ASGPR H1 and H2 subunits in primary human renal proximal tubular epithelial cells (RPTEC), in the human proximal tubular epithelial cell line HK2, and in human renal cortex was investigated using reverse-transcribed nested polymerase chain reaction. ASGPR protein expression as well as ligand binding and uptake were also examined using confocal microscopy and flow cytometry (fluorescence-activated cell sorting). Light microscopy of paraffin renal biopsy sections stained with a polyclonal antibody against the ASGPR showed proximal tubular epithelial cell staining of the cytoplasm and particularly in the basolateral region. Renal cortex and RPTEC specifically have mRNA for both H1 and H2 subunits of the ASGPR, but HK2 only expresses mRNA for H1. Using a monoclonal antibody, the presence of the ASGPR in RPTEC was shown by fluorescence-activated cell sorting and immunofluorescent staining. Specific binding and uptake of fluorescein isothiocyanate labelled asialofetuin which is a specific ASGPR ligand was also demonstrated in RPTEC. Primary renal proximal tubular epithelial cells have a functional ASGPR, consisting of the H1 and H2 subunits, that is capable of specific ligand binding and uptake. Copyright 2002 S. Karger AG, Basel

Small-Conductance Ca2+-Activated Potassium Channels Negatively Regulate Aldosterone Secretion in Human Adrenocortical Cells.

PubMed

Yang, Tingting; Zhang, Hai-Liang; Liang, Qingnan; Shi, Yingtang; Mei, Yan-Ai; Barrett, Paula Q; Hu, Changlong

2016-09-01

Aldosterone, which plays a key role in maintaining water and electrolyte balance, is produced by zona glomerulosa cells of the adrenal cortex. Autonomous overproduction of aldosterone from zona glomerulosa cells causes primary hyperaldosteronism. Recent clinical studies have highlighted the pathological role of the KCNJ5 potassium channel in primary hyperaldosteronism. Our objective was to determine whether small-conductance Ca(2+)-activated potassium (SK) channels may also regulate aldosterone secretion in human adrenocortical cells. We found that apamin, the prototypic inhibitor of SK channels, decreased membrane voltage, raised intracellular Ca(2+) and dose dependently increased aldosterone secretion from human adrenocortical H295R cells. By contrast, 1-Ethyl-2-benzimidazolinone, an agonist of SK channels, antagonized apamin's action and decreased aldosterone secretion. Commensurate with an increase in aldosterone production, apamin increased mRNA expression of steroidogenic acute regulatory protein and aldosterone synthase that control the early and late rate-limiting steps in aldosterone biosynthesis, respectively. In addition, apamin increased angiotensin II-stimulated aldosterone secretion, whereas 1-Ethyl-2-benzimidazolinone suppressed both angiotensin II- and high K(+)-stimulated production of aldosterone in H295R cells. These findings were supported by apamin-modulation of basal and angiotensin II-stimulated aldosterone secretion from acutely prepared slices of human adrenals. We conclude that SK channel activity negatively regulates aldosterone secretion in human adrenocortical cells. Genetic association studies are necessary to determine whether mutations in SK channel subtype 2 genes may also drive aldosterone excess in primary hyperaldosteronism. © 2016 American Heart Association, Inc.

Salmonella-secreted Virulence Factors

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

Heffron, Fred; Niemann, George; Yoon, Hyunjin

In this short review we discuss secreted virulence factors of Salmonella, which directly affect Salmonella interaction with its host. Salmonella secretes protein to subvert host defenses but also, as discussed, to reduce virulence thereby permitting the bacteria to persist longer and more successfully disperse. The type III secretion system (TTSS) is the best known and well studied of the mechanisms that enable secretion from the bacterial cytoplasm to the host cell cytoplasm. Other secretion systems include outer membrane vesicles, which are present in all Gram-negative bacteria examined to date, two-partner secretion, and type VI secretion will also be addressed. Excellentmore » reviews of Salmonella secreted effectors have focused on themes such as actin rearrangements, vesicular trafficking, ubiquitination, and the activities of the virulence factors themselves. This short review is based on S. Typhimurium infection of mice because it is a model of typhoid like disease in humans. We have organized effectors in terms of events that happen during the infection cycle and how secreted effectors may be involved.« less

Secreted CLIC3 drives cancer progression through its glutathione-dependent oxidoreductase activity

PubMed Central

Hernandez-Fernaud, Juan R.; Ruengeler, Elena; Casazza, Andrea; Neilson, Lisa J.; Pulleine, Ellie; Santi, Alice; Ismail, Shehab; Lilla, Sergio; Dhayade, Sandeep; MacPherson, Iain R.; McNeish, Iain; Ennis, Darren; Ali, Hala; Kugeratski, Fernanda G.; Al Khamici, Heba; van den Biggelaar, Maartje; van den Berghe, Peter V.E.; Cloix, Catherine; McDonald, Laura; Millan, David; Hoyle, Aoisha; Kuchnio, Anna; Carmeliet, Peter; Valenzuela, Stella M.; Blyth, Karen; Yin, Huabing; Mazzone, Massimiliano; Norman, Jim C.; Zanivan, Sara

2017-01-01

The secretome of cancer and stromal cells generates a microenvironment that contributes to tumour cell invasion and angiogenesis. Here we compare the secretome of human mammary normal and cancer-associated fibroblasts (CAFs). We discover that the chloride intracellular channel protein 3 (CLIC3) is an abundant component of the CAF secretome. Secreted CLIC3 promotes invasive behaviour of endothelial cells to drive angiogenesis and increases invasiveness of cancer cells both in vivo and in 3D cell culture models, and this requires active transglutaminase-2 (TGM2). CLIC3 acts as a glutathione-dependent oxidoreductase that reduces TGM2 and regulates TGM2 binding to its cofactors. Finally, CLIC3 is also secreted by cancer cells, is abundant in the stromal and tumour compartments of aggressive ovarian cancers and its levels correlate with poor clinical outcome. This work reveals a previously undescribed invasive mechanism whereby the secretion of a glutathione-dependent oxidoreductase drives angiogenesis and cancer progression by promoting TGM2-dependent invasion. PMID:28198360

Effect of adrenal hormones on thyroid secretion and thyroid hormones on adrenal secretion in the sheep.

PubMed Central

Falconer, I R; Jacks, F

1975-01-01

1. Previous work has shown that after stressful stimuli, sheep initially secrete increased amounts of thyroid hormone, at a time when adrenal secretion is also elevated. 2. This study was designed to evaluate (a) any short-term activation or inhibition of thyroid secretion by exogenous cortisol or ACTH administered in quantities comparable to those secreted after stress in sheep and (b) any short-term effect that exogenous thyroxine or triiodothyronine may have on the concentration of plasma cortisol in the sheep. 3. Thyroid activity was measured by determination of plasma protein bound 125I (PB125I) and total 125I in thyroid vein and mixed venous (jugular) blood. Plasma cortisol and thyroxine concentrations were measured by a competitive protein-binding assay at intervals for up to 5 hr after commencement of the experiment. 4. No evidence of an activation of thyroid secretion was found during cortisol or ACTH infusion, as monitored by thyroid vein PB125I. Similarly there was no evidence of any inhibition of thyroid function, as measured by continued secretion of thyroid hormones into thyroid vein blood. 5. No effect on plasma cortisol concentration due to thyroid hormone treatment was observed. 6. It was concluded that (a) elevated circulating corticosteroids in physiological concentrations have no short-term effects on thyroid activity in the sheep and (b) the short-term alterations in thyroid and adrenal cortical secretion observed during stress in the sheep could not be attributed to direct interaction of elevated thyroid hormone concentrations with adrenal cortical secretion. PMID:170400

MDM2 prevents spontaneous tubular epithelial cell death and acute kidney injury

PubMed Central

Thomasova, Dana; Ebrahim, Martrez; Fleckinger, Kristina; Li, Moying; Molnar, Jakob; Popper, Bastian; Liapis, Helen; Kotb, Ahmed M; Siegerist, Florian; Endlich, Nicole; Anders, Hans-Joachim

2016-01-01

Murine double minute-2 (MDM2) is an E3-ubiquitin ligase and the main negative regulator of tumor suppressor gene p53. MDM2 has also a non-redundant function as a modulator of NF-kB signaling. As such it promotes proliferation and inflammation. MDM2 is highly expressed in the unchallenged tubular epithelial cells and we hypothesized that MDM2 is necessary for their survival and homeostasis. MDM2 knockdown by siRNA or by genetic depletion resulted in demise of tubular cells in vitro. This phenotype was completely rescued by concomitant knockdown of p53, thus suggesting p53 dependency. In vivo experiments in the zebrafish model demonstrated that the tubulus cells of the larvae undergo cell death after the knockdown of mdm2. Doxycycline-induced deletion of MDM2 in tubular cell-specific MDM2-knockout mice Pax8rtTa-cre; MDM2f/f caused acute kidney injury with increased plasma creatinine and blood urea nitrogen and sharp decline of glomerular filtration rate. Histological analysis showed massive swelling of renal tubular cells and later their loss and extensive tubular dilation, markedly in proximal tubules. Ultrastructural changes of tubular epithelial cells included swelling of the cytoplasm and mitochondria with the loss of cristae and their transformation in the vacuoles. The pathological phenotype of the tubular cell-specific MDM2-knockout mouse model was completely rescued by co-deletion of p53. Tubular epithelium compensates only partially for the cell loss caused by MDM2 depletion by proliferation of surviving tubular cells, with incomplete MDM2 deletion, but rather mesenchymal healing occurs. We conclude that MDM2 is a non-redundant survival factor for proximal tubular cells by protecting them from spontaneous p53 overexpression-related cell death. PMID:27882940

Simultaneous recording of t-tubular electrical activity and Ca2+-release in heart failure

NASA Astrophysics Data System (ADS)

Crocini, C.; Coppini, R.; Ferrantini, C.; Yan, P.; Loew, L.; Tesi, C.; Poggesi, C.; Cerbai, E.; Pavone, F. S.; Sacconi, L.

2014-05-01

T-tubules (TT) are invaginations of the surface sarcolemma (SS) that mediate the rapid propagation of the action potential (AP) to the cardiomyocyte core. We employed the advantages of an ultrafast random access multi-photon (RAMP) microscope (Sacconi et al., PNAS 2012) with a double staining approach to optically record t-tubular AP and, simultaneously, the corresponding local Ca2+-release in different positions across the cardiomyocytes. Despite a uniform AP between SS and TT at steady-state stimulation, in control cardiomyocytes we observed a non-negligible be variability of local Ca2+-transient amplitude and kinetics. This variability was significantly reduced by applying 0.1μM Isoproterenol, which increases the opening probability of Ca2+-release units. In the rat heart failure model (HF), we previously demonstrated that some tubular elements fail to propagate AP. We found that the tubules unable to propagate AP, displayed a reduced correspondent Ca2+-transient amplitude as well as a slower Ca2+ rise compared to electrically coupled tubules. Moreover variability of Ca2+-transient kinetics were increased in HF. Finally, TT that did not show AP, occasionally exhibited spontaneous depolarizations that were never accompanied by local Ca2+-release in the absence of any pro-arrhythmogenic stimulation. Simultaneous recording of AP and Ca2+-transient allows us to probe the spatio-temporal variability of Ca2+-release, whereas the investigation of Ca2+-transient in HF discloses an unexpected uncoupling between t-tubular depolarization and Ca2+-release in remodeled tubules. This work was funded by the European Union 7th Framework Program (FP7/2007- 2013) under grant agreement n° 284464, 241526, by the Italian Ministry of University and Research (NANOMAX), and by Telethon-Italy (GGP13162).

Effect of gemfibrozil on apolipoprotein B secretion and diacylglycerol acyltransferase activity in human hepatoblastoma (HepG2) cells.

PubMed

Zhu, Daming; Ganji, Shobha H; Kamanna, Vaijinath S; Kashyap, Moti L

2002-10-01

The mechanism of action of a widely used drug gemfibrozil to reduce triglycerides (TG) and apolipoprotein B (apo B) is incompletely understood. Using human hepatoblastoma (HepG2) cells, we examined the effect of gemfibrozil on apo B secretion and TG synthesis catalyzed by diacylglycerol acyltransferase (DGAT), primary processes associated with the secretion of LDL. Gemfibrozil significantly decreased apo B secretion by HepG2 cells. It decreased oleate-induced stimulation of apo B secretion, suggesting that gemfibrozil-mediated inhibition of apo B secretion may be dependent on the synthesis of TG catalyzed by DGAT. Pre-incubation of HepG2 cells with gemfibrozil (200-400 micromol/l for 48 h) significantly inhibited microsomal DGAT activity. When added directly to the DGAT assay system containing control microsomes, gemfibrozil significantly inhibited the activity of DGAT by 14-25%. Gemfibrozil (200-400 micromol/l) inhibited TG synthesis by 47-50% as measured by the incorporation of 3H-oleic acid into TG. The data indicate that gemfibrozil inhibits DGAT activity resulting in decreased synthesis of TG and its availability for apo B lipidation rendering it susceptible to intracellular apo B degradation leading to the decreased secretion. These in-vitro data suggest a novel additional mechanism by which gemfibrozil lowers plasma TG and atherogenic apo B lipoproteins in dyslipidemic patients.

Biochemical actions of glucocorticoids on macrophages in culture. Specific inhibition of elastase, collagenase, and plasminogen activator secretion and effects on other metabolic functions

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

Werb, Z.

1978-01-01

The effects of glucocorticoids on biochemical functions of macrophages from man, mouse, rabbit, and guinea pig were examined. Secretion of plasminogen activator by human peripheral blood monocytes was decreased 50% with 1 nM dexamethasone. Differentiation of murine monocytic and granulocytic colonies in agar from bone marrow precursors was decreased 50% at 7 days with 20 nM dexamethasone. Secretion of elastase, collagenase, and plasminogen activator by resident and thioglycollate-elicited mouse peritoneal macrophages was decreased by dexamethasone, cortisol, and triamcinolone acetonide (1 to 1,000 nM), but not by progesterone, estradiol, and dihydrotestosterone (1,000 nM); in contast, secretion of lysozyme was not affectedmore » by glucocorticoids. The inhibition of macrophage secretion by dexamethasone was both time and dose dependent. Inhibition of macrophage secretion increased with increasing glucocorticoid concentration. Half-maximum inhibition of secretion of elastase, collagenase, and plasminogen activator was seen at dexamethasone concentrations (1 to 10 nM) similar to those that half-saturated the specific glucocorticoid receptors. At high concentrations of dexamethasone (100 to 1,000 nM) the secretion of plasminogen activator was inhibited to a greater extent (>95%) than the secretion of elastase (60 to 80%).Progesterone alone had no effect on secretion, but blocked the inhibitory effects of dexamethasone and cortisol. Secretion of collagenase, neutral proteinases, and plasminogen activator by elicited rabbit alveolar macrophages was inhibited with glucocorticoids (0.1 to 100 nM) but not with progesterone or sex steroids. Secretion of a neutral elastinolytic proteinase by guinea pig alveolar macrophages was also inhibited by dexamethasone.« less

New methods for the geometrical analysis of tubular organs.

PubMed

Grélard, Florent; Baldacci, Fabien; Vialard, Anne; Domenger, Jean-Philippe

2017-12-01

This paper presents new methods to study the shape of tubular organs. Determining precise cross-sections is of major importance to perform geometrical measurements, such as diameter, wall-thickness estimation or area measurement. Our first contribution is a robust method to estimate orthogonal planes based on the Voronoi Covariance Measure. Our method is not relying on a curve-skeleton computation beforehand. This means our orthogonal plane estimator can be used either on the skeleton or on the volume. Another important step towards tubular organ characterization is achieved through curve-skeletonization, as skeletons allow to compare two tubular organs, and to perform virtual endoscopy. Our second contribution is dedicated to correcting common defects of the skeleton by new pruning and recentering methods. Finally, we propose a new method for curve-skeleton extraction. Various results are shown on different types of segmented tubular organs, such as neurons, airway-tree and blood vessels. Copyright © 2017 Elsevier B.V. All rights reserved.

Vesicular secretion of auxin

PubMed Central

Schlicht, Markus; Volkmann, Dieter; Mancuso, Stefano

2008-01-01

The plant hormone auxin is secreted in root apices via phospholipase Dζ2 (PLDζ2) activity which produces specific population of phosphatidic acid that stimulates secretion of vesicles enriched with auxin. These vesicles were reported to be localized at plant synapses which are active in auxin secretion, especially at the transition zone of the root apex. There are several implications of this vesicular secretion of auxin. In root apices, auxin emerges as plant neurotransmitter-like signal molecule which coordinates activities of adjacent cells via electric and chemical signaling. Putative quantal release of auxin after electrical stimulation, if confirmed, would be part of neuronal communication between plant cells. As auxin transport across plant synapses is tightly linked with integrated sensory perception of environment, especially of omnipresent gravity and light, this process is proposed to mediate the plant perception of environment. These neuronal features allow sessile plants to integrate multitude of sensory signals into the adaptive behavior of whole plants and the animal-like exploratory behavior of growing roots. PMID:19704646

Nonlinear Analysis of Bonded Composite Tubular Lap Joints

NASA Technical Reports Server (NTRS)

Oterkus, E.; Madenci, E.; Smeltzer, S. S., III; Ambur, D. R.

2005-01-01

The present study describes a semi-analytical solution method for predicting the geometrically nonlinear response of a bonded composite tubular single-lap joint subjected to general loading conditions. The transverse shear and normal stresses in the adhesive as well as membrane stress resultants and bending moments in the adherends are determined using this method. The method utilizes the principle of virtual work in conjunction with nonlinear thin-shell theory to model the adherends and a cylindrical shear lag model to represent the kinematics of the thin adhesive layer between the adherends. The kinematic boundary conditions are imposed by employing the Lagrange multiplier method. In the solution procedure, the displacement components for the tubular joint are approximated in terms of non-periodic and periodic B-Spline functions in the longitudinal and circumferential directions, respectively. The approach presented herein represents a rapid-solution alternative to the finite element method. The solution method was validated by comparison against a previously considered tubular single-lap joint. The steep variation of both peeling and shearing stresses near the adhesive edges was successfully captured. The applicability of the present method was also demonstrated by considering tubular bonded lap-joints subjected to pure bending and torsion.

Bcl-2 protects tubular epithelial cells from ischemia reperfusion injury by inhibiting apoptosis.

PubMed

Suzuki, Chigure; Isaka, Yoshitaka; Shimizu, Shigeomi; Tsujimoto, Yoshihide; Takabatake, Yoshitsugu; Ito, Takahito; Takahara, Shiro; Imai, Enyu

2008-01-01

Ischemia followed by reperfusion leads to severe organ injury and dysfunction. Inflammation is considered to be the most important cause of graft dysfunction in kidney transplantation subjected to ischemia. The mechanism that triggers inflammation and renal injury after ischemia remains to be elucidated; however, cellular stress may induce apoptosis during the first hours and days after transplantation, which might play a crucial role in early graft dysfunction. Bcl-2 is known to inhibit apoptosis induced by the etiological factors promoting ischemia and reperfusion injury. Accordingly, we hypothesized that an augmentation of the antiapoptotic factor Bcl-2 may thus protect tubular epithelial cells by inhibiting apoptosis, thereby ameliorating the subsequent tubulointerstitial injury. We examined the effects of Bcl-2 overexpression on ischemia-reperfusion (I/R) injury using Bcl-2 transgenic mice (Bcl-2 TG) and their wild-type littermates (WT). To investigate the effects of I/R injury, the left renal artery and vein were clamped for 45 min, followed by reperfusion for 0-96 h. Bcl-2 TG exhibited decreased active caspase protein in the tubular cells, which led to a reduction in TUNEL-positive apoptotic cells. Consequently, interstitial fibrosis and phenotypic changes were ameliorated in Bcl-2 TG. In conclusion, Bcl-2 augmentation protected renal tubular epithelial cells from I/R, and subsequent interstitial injury by inhibiting tubular apoptosis.

Hyperactivation of Nrf2 in early tubular development induces nephrogenic diabetes insipidus

PubMed Central

Suzuki, Takafumi; Seki, Shiori; Hiramoto, Keiichiro; Naganuma, Eriko; Kobayashi, Eri H.; Yamaoka, Ayaka; Baird, Liam; Takahashi, Nobuyuki; Sato, Hiroshi; Yamamoto, Masayuki

2017-01-01

NF-E2-related factor-2 (Nrf2) regulates cellular responses to oxidative and electrophilic stress. Loss of Keap1 increases Nrf2 protein levels, and Keap1-null mice die of oesophageal hyperkeratosis because of Nrf2 hyperactivation. Here we show that deletion of oesophageal Nrf2 in Keap1-null mice allows survival until adulthood, but the animals develop polyuria with low osmolality and bilateral hydronephrosis. This phenotype is caused by defects in water reabsorption that are the result of reduced aquaporin 2 levels in the kidney. Renal tubular deletion of Keap1 promotes nephrogenic diabetes insipidus features, confirming that Nrf2 activation in developing tubular cells causes a water reabsorption defect. These findings suggest that Nrf2 activity should be tightly controlled during development in order to maintain renal homeostasis. In addition, tissue-specific ablation of Nrf2 in Keap1-null mice might create useful animal models to uncover novel physiological functions of Nrf2. PMID:28233855

FGF21 is induced in cisplatin nephrotoxicity to protect against kidney tubular cell injury.

PubMed

Li, Fanghua; Liu, Zhiwen; Tang, Chengyuan; Cai, Juan; Dong, Zheng

2018-01-22

Cisplatin, a widely used cancer therapy drug, induces nephrotoxicity or acute kidney injury (AKI), but the underlying mechanism remains unclear, and renal protective approaches are not available. Fibroblast growth factor (FGF)21 is an endocrine factor that regulates glucose uptake, metabolism, and energy expenditure. However, recent work has also implicated FGF21 in cellular stress response under pathogenic conditions. The role and regulation of FGF21 in AKI are unclear. Here, we show that FGF21 was dramatically induced during cisplatin treatment of renal tubular cells in vitro and mouse kidneys in vivo. The inductive response was suppressed by pifithrin (a pharmacological inhibitor of P53), suggesting a role of P53 in FGF21 induction. In cultured renal tubular cells, knockdown of FGF21 aggravated cisplatin-induced apoptosis, whereas supplementation of recombinant FGF21 was protective. Consistently, recombinant FGF21 alleviated cisplatin-induced kidney dysfunction, tissue damage, and tubular apoptosis in mice. Mechanistically, FGF21 suppressed P53 induction and activation during cisplatin treatment. Together, these results indicate that FGF21 is induced during cisplatin nephrotoxicity to protect renal tubules, and recombinant FGF21 may have therapeutic potential.-Li, F., Liu, Z., Tang, C., Cai, J., Dong, Z. FGF21 is induced in cisplatin nephrotoxicity to protect against kidney tubular cell injury.

Vibration analysis and sound field characteristics of a tubular ultrasonic radiator.

PubMed

Liang, Zhaofeng; Zhou, Guangping; Zhang, Yihui; Li, Zhengzhong; Lin, Shuyu

2006-12-01

A sort of tubular ultrasonic radiator used in ultrasonic liquid processing is studied. The frequency equation of the tubular radiator is derived, and its radiated sound field in cylindrical reactor is calculated using finite element method and recorded by means of aluminum foil erosion. The results indicate that sound field of tubular ultrasonic radiator in cylindrical reactor appears standing waves along both its radial direction and axial direction, and amplitudes of standing waves decrease gradually along its radial direction, and the numbers of standing waves along its axial direction are equal to the axial wave numbers of tubular radiator. The experimental results are in good agreement with calculated results.

Nerve regeneration using tubular scaffolds from biodegradable polyurethane.

PubMed

Hausner, T; Schmidhammer, R; Zandieh, S; Hopf, R; Schultz, A; Gogolewski, S; Hertz, H; Redl, H

2007-01-01

In severe nerve lesion, nerve defects and in brachial plexus reconstruction, autologous nerve grafting is the golden standard. Although, nerve grafting technique is the best available approach a major disadvantages exists: there is a limited source of autologous nerve grafts. This study presents data on the use of tubular scaffolds with uniaxial pore orientation from experimental biodegradable polyurethanes coated with fibrin sealant to regenerate a 8 mm resected segment of rat sciatic nerve. Tubular scaffolds: prepared by extrusion of the polymer solution in DMF into water coagulation bath. The polymer used for the preparation of tubular scaffolds was a biodegradable polyurethane based on hexamethylene diisocyanate, poly(epsilon-caprolactone) and dianhydro-D-sorbitol. EXPERIMENTAL MODEL: Eighteen Sprague Dawley rats underwent mid-thigh sciatic nerve transection and were randomly assigned to two experimental groups with immediate repair: (1) tubular scaffold, (2) 180 degrees rotated sciatic nerve segment (control). Serial functional measurements (toe spread test, placing tests) were performed weekly from 3rd to 12th week after nerve repair. On week 12, electrophysiological assessment was performed. Sciatic nerve and scaffold/nerve grafts were harvested for histomorphometric analysis. Collagenic connective tissue, Schwann cells and axons were evaluated in the proximal nerve stump, the scaffold/nerve graft and the distal nerve stump. The implants have uniaxially-oriented pore structure with a pore size in the range of 2 micorm (the pore wall) and 75 x 700 microm (elongated pores in the implant lumen). The skin of the tubular implants was nonporous. Animals which underwent repair with tubular scaffolds of biodegradable polyurethanes coated with diluted fibrin sealant had no significant functional differences compared with the nerve graft group. Control group resulted in a trend-wise better electrophysiological recovery but did not show statistically significant

Mathematical modeling of methyl ester concentration distribution in a continuous membrane tubular reactor and comparison with conventional tubular reactor

NASA Astrophysics Data System (ADS)

Talaghat, M. R.; Jokar, S. M.; Modarres, E.

2017-10-01

The reduction of fossil fuel resources and environmental issues made researchers find alternative fuels include biodiesels. One of the most widely used methods for production of biodiesel on a commercial scale is transesterification method. In this work, the biodiesel production by a transesterification method was modeled. Sodium hydroxide was considered as a catalyst to produce biodiesel from canola oil and methanol in a continuous tubular ceramic membranes reactor. As the Biodiesel production reaction from triglycerides is an equilibrium reaction, the reaction rate constants depend on temperature and related linearly to catalyst concentration. By using the mass balance for a membrane tubular reactor and considering the variation of raw materials and products concentration with time, the set of governing equations were solved by numerical methods. The results clearly show the superiority of membrane reactor than conventional tubular reactors. Afterward, the influences of molar ratio of alcohol to oil, weight percentage of the catalyst, and residence time on the performance of biodiesel production reactor were investigated.

Dysfunctional tubular endoplasmic reticulum constitutes a pathological feature of Alzheimer's disease.

PubMed

Sharoar, M G; Shi, Q; Ge, Y; He, W; Hu, X; Perry, G; Zhu, X; Yan, R

2016-09-01

Pathological features in Alzheimer's brains include mitochondrial dysfunction and dystrophic neurites (DNs) in areas surrounding amyloid plaques. Using a mouse model that overexpresses reticulon 3 (RTN3) and spontaneously develops age-dependent hippocampal DNs, here we report that DNs contain both RTN3 and REEPs, topologically similar proteins that can shape tubular endoplasmic reticulum (ER). Importantly, ultrastructural examinations of such DNs revealed gradual accumulation of tubular ER in axonal termini, and such abnormal tubular ER inclusion is found in areas surrounding amyloid plaques in biopsy samples from Alzheimer's disease (AD) brains. Functionally, abnormally clustered tubular ER induces enhanced mitochondrial fission in the early stages of DN formation and eventual mitochondrial degeneration at later stages. Furthermore, such DNs are abrogated when RTN3 is ablated in aging and AD mouse models. Hence, abnormally clustered tubular ER can be pathogenic in brain regions: disrupting mitochondrial integrity, inducing DNs formation and impairing cognitive function in AD and aging brains.

Secret Key Generation via a Modified Quantum Secret Sharing Protocol

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

Smith IV, Amos M; Evans, Philip G; Lawrie, Benjamin J

We present and experimentally show a novel protocol for distributing secret information between two and only two parties in a N-party single-qubit Quantum Secret Sharing (QSS) system. We demonstrate this new algorithm with N = 3 active parties over 6km of telecom. ber. Our experimental device is based on the Clavis2 Quantum Key Distribution (QKD) system built by ID Quantique but is generalizable to any implementation. We show that any two out of the N parties can build secret keys based on partial information from each other and with collaboration from the remaining N > 2 parties. This algorithm allowsmore » for the creation of two-party secret keys were standard QSS does not and signicantly reduces the number of resources needed to implement QKD on a highly connected network such as the electrical grid.« less

49 CFR 230.55 - Tubular type water and lubricator glasses and shields.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Tubular type water and lubricator glasses and... STANDARDS Boilers and Appurtenances Water Glasses and Gauge Cocks § 230.55 Tubular type water and lubricator glasses and shields. (a) Water glasses. Tubular type water glasses shall be renewed at each 92 service day...

Thioredoxin interacting protein (TXNIP) regulates tubular autophagy and mitophagy in diabetic nephropathy through the mTOR signaling pathway

PubMed Central

Huang, Chunling; Zhang, Yuan; Kelly, Darren J.; Tan, Christina Y. R.; Gill, Anthony; Cheng, Delfine; Braet, Filip; Park, Jin-Sung; Sue, Carolyn M.; Pollock, Carol A.; Chen, Xin-Ming

2016-01-01

Hyperglycemia upregulates thioredoxin interacting protein (TXNIP) expression, which in turn induces ROS production, inflammatory and fibrotic responses in the diabetic kidney. Dysregulation of autophagy contributes to the development of diabetic nephropathy. However, the interaction of TXNIP with autophagy/mitophagy in diabetic nephropathy is unknown. In this study, streptozotocin-induced diabetic rats were given TXNIP DNAzyme or scrambled DNAzyme for 12 weeks respectively. Fibrotic markers, mitochondrial function and mitochondrial reactive oxygen species (mtROS) were assessed in kidneys. Tubular autophagy and mitophagy were determined in kidneys from both human and rats with diabetic nephropathy. TXNIP and autophagic signaling molecules were examined. TXNIP DNAzyme dramatically attenuated extracellular matrix deposition in the diabetic kidneys compared to the control DNAzyme. Accumulation of autophagosomes and reduced autophagic clearance were shown in tubular cells of human diabetic compared to non-diabetic kidneys, which was reversed by TXNIP DNAzyme. High glucose induced mitochondrial dysfunction and mtROS production, and inhibited mitophagy in proximal tubular cells, which was reversed by TXNIP siRNA. TXNIP inhibition suppressed diabetes-induced BNIP3 expression and activation of the mTOR signaling pathway. Collectively, hyperglycemia-induced TXNIP contributes to the dysregulation of tubular autophagy and mitophagy in diabetic nephropathy through activation of the mTOR signaling pathway. PMID:27381856

Fascin-1 is released from proximal tubular cells in response to calcineurin inhibitors (CNIs) and correlates with isometric vacuolization in kidney transplanted patients

PubMed Central

Jacobs-Cachá, Conxita; Torres, Irina B; López-Hellín, Joan; Cantarell, Carme; Azancot, María A; Román, Antonio; Moreso, Francesc; Serón, Daniel; Meseguer, Anna; Sarró, Eduard

2017-01-01

Immunosuppression based on calcineurin inhibitors (CNIs) has greatly improved organ transplantation, although subsequent nephrotoxicity significantly hinders treatment success. There are no currently available specific soluble biomarkers for CNI-induced nephrotoxicity and diagnosis relies on renal biopsy, which is costly, invasive and may cause complications. Accordingly, identification of non-invasive biomarkers distinguishing CNI-induced kidney tubular damage from that of other etiologies would greatly improve diagnosis and enable more precise dosage adjustment. For this purpose, HK-2 cells, widely used to model human proximal tubule, were treated with CNIs cyclosporine-A and FK506, or staurosporine as a calcineurin-independent toxic compound, and secretomes of each treatment were analyzed by proteomic means. Among the differentially secreted proteins identified, only fascin-1 was specifically released by both CNIs but not by staurosporine. To validate fascin-1 as a biomarker of CNI-induced tubular toxicity, fascin-1 levels were analyzed in serum and urine from kidney-transplanted patients under CNIs treatment presenting or not isometric vacuolization (IV), which nowadays represents the main histological hallmark of CNI-induced tubular damage. Patients with chronic kidney disease (CKD) and healthy volunteers were used as controls. Our results show that urinary fascin-1 was only significantly elevated in the subset of CNI-treated patients presenting IV. Moreover, fascin-1 anticipated the rise of sCr levels in serially collected urine samples from CNI-treated pulmonary-transplanted patients, where a decline in kidney function and serum creatinine (sCr) elevation was mainly attributed to CNIs treatment. In conclusion, our results point towards fascin-1 as a putative soluble biomarker of CNI-induced damage in the kidney tubular compartment. PMID:28979691

Fascin-1 is released from proximal tubular cells in response to calcineurin inhibitors (CNIs) and correlates with isometric vacuolization in kidney transplanted patients.

PubMed

Jacobs-Cachá, Conxita; Torres, Irina B; López-Hellín, Joan; Cantarell, Carme; Azancot, María A; Román, Antonio; Moreso, Francesc; Serón, Daniel; Meseguer, Anna; Sarró, Eduard

2017-01-01

Immunosuppression based on calcineurin inhibitors (CNIs) has greatly improved organ transplantation, although subsequent nephrotoxicity significantly hinders treatment success. There are no currently available specific soluble biomarkers for CNI-induced nephrotoxicity and diagnosis relies on renal biopsy, which is costly, invasive and may cause complications. Accordingly, identification of non-invasive biomarkers distinguishing CNI-induced kidney tubular damage from that of other etiologies would greatly improve diagnosis and enable more precise dosage adjustment. For this purpose, HK-2 cells, widely used to model human proximal tubule, were treated with CNIs cyclosporine-A and FK506, or staurosporine as a calcineurin-independent toxic compound, and secretomes of each treatment were analyzed by proteomic means. Among the differentially secreted proteins identified, only fascin-1 was specifically released by both CNIs but not by staurosporine. To validate fascin-1 as a biomarker of CNI-induced tubular toxicity, fascin-1 levels were analyzed in serum and urine from kidney-transplanted patients under CNIs treatment presenting or not isometric vacuolization (IV), which nowadays represents the main histological hallmark of CNI-induced tubular damage. Patients with chronic kidney disease (CKD) and healthy volunteers were used as controls. Our results show that urinary fascin-1 was only significantly elevated in the subset of CNI-treated patients presenting IV. Moreover, fascin-1 anticipated the rise of sCr levels in serially collected urine samples from CNI-treated pulmonary-transplanted patients, where a decline in kidney function and serum creatinine (sCr) elevation was mainly attributed to CNIs treatment. In conclusion, our results point towards fascin-1 as a putative soluble biomarker of CNI-induced damage in the kidney tubular compartment.

AMP-activated protein kinase and adenosine are both metabolic modulators that regulate chloride secretion in the shark rectal gland ( Squalus acanthias).

PubMed

Neuman, Rugina I; van Kalmthout, Juliette A M; Pfau, Daniel J; Menendez, Dhariyat M; Young, Lawrence H; Forrest, John N

2018-04-01

The production of endogenous adenosine during secretagogue stimulation of CFTR leads to feedback inhibition limiting further chloride secretion in the rectal gland of the dogfish shark (Squalus acanthias). In the present study, we examined the role of AMP-kinase (AMPK) as an energy sensor also modulating chloride secretion through CFTR. We found that glands perfused with forskolin and isobutylmethylxanthine (F + I), potent stimulators of chloride secretion in this ancient model, caused significant phosphorylation of the catalytic subunit Thr 172 of AMPK. These findings indicate that AMPK is activated during energy-requiring stimulated chloride secretion. In molecular studies, we confirmed that the activating Thr 172 site is indeed present in the α-catalytic subunit of AMPK in this ancient gland, which reveals striking homology to AMPKα subunits sequenced in other vertebrates. When perfused rectal glands stimulated with F + I were subjected to severe hypoxic stress or perfused with pharmacologic inhibitors of metabolism (FCCP or oligomycin), phosphorylation of AMPK Thr 172 was further increased and chloride secretion was dramatically diminished. The pharmacologic activation of AMPK with AICAR-inhibited chloride secretion, as measured by short-circuit current, when applied to the apical side of shark rectal gland monolayers in primary culture. These results indicate that that activated AMPK, similar to adenosine, transmits an inhibitory signal from metabolism, that limits chloride secretion in the shark rectal gland.

Mars Life? - Microscopic Tubular Structures

NASA Image and Video Library

1996-08-09

This electron microscope image shows tubular structures of likely Martian origin. These structures are very similar in size and shape to extremely tiny microfossils found in some Earth rocks. http://photojournal.jpl.nasa.gov/catalog/PIA00287

Renal pathophysiologic role of cortical tubular inclusion bodies.

PubMed

Radi, Zaher A; Stewart, Zachary S; Grzemski, Felicity A; Bobrowski, Walter F

2013-01-01

Renal tubular inclusion bodies are rarely associated with drug administration. The authors describe the finding of renal cortical tubular intranuclear and intracytoplasmic inclusion bodies associated with the oral administration of a norepinephrine/serotonin reuptake inhibitor (NSRI) test article in Sprague-Dawley (SD) rats. Rats were given an NSRI daily for 4 weeks, and kidney histopathologic, ultrastructural pathology, and immunohistochemical examinations were performed. Round eosinophilic intranuclear inclusion bodies were observed histologically in the tubular epithelial cells of the renal cortex in male and female SD rats given the NSRI compound. No evidence of degeneration or necrosis was noted in the inclusion-containing renal cells. By ultrastructural pathology, inclusion bodies consisted of finely granular, amorphous, and uniformly stained nonmembrane-bound material. By immunohistochemistry, inclusion bodies stained positive for d-amino acid oxidase (DAO) protein. In addition, similar inclusion bodies were noted in the cytoplasmic tubular epithelial compartment by ultrastructural and immunohistochemical examination.  This is the first description of these renal inclusion bodies after an NSRI test article administration in SD rats. Such drug-induced renal inclusion bodies are rat-specific, do not represent an expression of nephrotoxicity, represent altered metabolism of d-amino acids, and are not relevant to human safety risk assessment.

Chromium picolinate inhibits resistin secretion in insulin-resistant 3T3-L1 adipocytes via activation of amp-activated protein kinase.

PubMed

Wang, Yi-Qun; Dong, Yi; Yao, Ming-Hui

2009-08-01

1. Chromium picolinate (CrPic) has been recommended as an alternative therapeutic regimen for Type 2 diabetes mellitus (T2DM). However, the molecular mechanism underlying the action of CrPic is poorly understood. 2. Using normal and insulin-resistant 3T3-L1 adipocytes, we examined the effects of CrPic on the gene transcription and secretion of adiponectin and resistin. In addition, using immunoblotting, ELISA and real-time reverse transcription-polymerase chain reaction (RT-PCR), we investigated the effects of 10 nmol/L CrPic for 24 h on AMP-activated protein kinase (AMPK) to determine whether this pathway contributed to the regulation of adiponectin and resistin expression and secretion. 3. Chromium picolinate did not modulate the expression of adiponectin and resistin; however, it did significantly inhibit the secretion of resistin, but not adiponectin, by normal and insulin-resistant 3T3-L1 adipocytes in vitro. Furthermore, although CrPic markedly elevated levels of phosphorylated AMPK and acetyl CoA carboxylase in 3T3-L1 adipocytes, it had no effect on the levels of AMPK alpha-1 and alpha-2 mRNA transcripts. Importantly, inhibition of AMPK by 2 h pretreatment of cells with 20 micromol/L compound C completely abolished the CrPic-induced suppression of resistin secretion. 4. In conclusion, the data suggest that CrPic inhibits resistin secretion via activation of AMPK in normal and insulin-resistant 3T3-L1 adipocytes.

Kinetics of carbendazim degradation in a horizontal tubular biofilm reactor.

PubMed

Alvarado-Gutiérrez, María Luisa; Ruiz-Ordaz, Nora; Galíndez-Mayer, Juvencio; Santoyo-Tepole, Fortunata; Curiel-Quesada, Everardo; García-Mena, Jaime; Ahuatzi-Chacón, Deifilia

2017-04-01

The fungicide carbendazim is an ecotoxic agent affecting aquatic biota. Due to its suspected hormone-disrupting effects, it is considered a "priority hazard substance" by the Water Framework Directive of the European Commission, and its degradation is of major concern. In this work, a horizontal tubular biofilm reactor (HTBR) operating in plug-flow regime was used to study the kinetics of carbendazim removal by an acclimated microbial consortium. The reactor was operated in steady state continuous culture at eight different carbendazim loading rates. The concentrations of the fungicide were determined at several distances of the HTBR. At the loading rates tested, the highest instantaneous removal rates were observed in the first section of the tubular biofilm reactor. No evidence of inhibition of the catabolic activity of the microbial community was found. Strains of the genera Flectobacillus, Klebsiella, Stenotrophomonas, and Flavobacterium were identified in the biofilm; the last three degrade carbendazim in axenic culture.

Renal tubular function in children with tyrosinaemia type I treated with nitisinone.

PubMed

Santra, S; Preece, M A; Hulton, S-A; McKiernan, P J

2008-06-01

Tyrosinaemia type I (TTI) is an inherited deficiency in the enzyme fumarylacetoacetate hydrolase and is frequently complicated by renal tubular dysfunction which may persist in some patients after hepatic transplantation. Nitisinone has revolutionized the management of TTI but its effect on renal tubular dysfunction has not been described in a large cohort of patients. To document the incidence and progression of renal tubular dysfunction in children with TTI treated with nitisinone at a single centre. Twenty-one patients with TTI from a single centre were treated with nitisinone for at least 12 months. Median age at first treatment was 17 weeks (range 1 week to 27 months). Nine patients (43%) presented in acute liver failure, seven (33%) had a chronic presentation and five (24%) were detected pre-clinically. A retrospective case analysis of plasma phosphate, urinary protein/creatinine ratio and tubular reabsorption of phosphate was performed for all patients as markers of tubular function. Renal ultrasounds were examined for evidence of nephrocalcinosis and where available, skeletal radiographs for rickets. All patients had biochemical evidence of renal tubular dysfunction at presentation. After nitisinone and dietary treatment were started, all three markers normalized within one year. Four children had clinical rickets at presentation (which improved), of whom one had nephrocalcinosis, which did not reverse on nitisinone. No child redeveloped tubular dysfunction after commencing nitisinone. All patients with TTI had evidence of tubular dysfunction at presentation and in all cases this resolved with nitisinone and dietary control. The tubulopathy associated with TTI is reversible.

Performance of Serum Creatinine and Kidney Injury Biomarkers for Diagnosing Histologic Acute Tubular Injury.

PubMed

Moledina, Dennis G; Hall, Isaac E; Thiessen-Philbrook, Heather; Reese, Peter P; Weng, Francis L; Schröppel, Bernd; Doshi, Mona D; Wilson, F Perry; Coca, Steven G; Parikh, Chirag R

2017-12-01

The diagnosis of acute kidney injury (AKI), which is currently defined as an increase in serum creatinine (Scr) concentration, provides little information on the condition's actual cause. To improve phenotyping of AKI, many urinary biomarkers of tubular injury are being investigated. Because AKI cases are not frequently biopsied, the diagnostic accuracy of concentrations of Scr and urinary biomarkers for histologic acute tubular injury is unknown. Cross-sectional analysis from multicenter prospective cohort. Hospitalized deceased kidney donors on whom kidney biopsies were performed at the time of organ procurement for histologic evaluation. (1) AKI diagnosed by change in Scr concentration during donor hospitalization and (2) concentrations of urinary biomarkers (neutrophil gelatinase-associated lipocalin [NGAL], liver-type fatty acid-binding protein [L-FABP], interleukin 18 [IL-18], and kidney injury molecule 1 [KIM-1]) measured at organ procurement. Histologic acute tubular injury. Of 581 donors, 98 (17%) had mild acute tubular injury and 57 (10%) had severe acute tubular injury. Overall, Scr-based AKI had poor diagnostic performance for identifying histologic acute tubular injury and 49% of donors with severe acute tubular injury did not have AKI. The area under the receiver operating characteristic curve (AUROC) of change in Scr concentration for diagnosing severe acute tubular injury was 0.58 (95% CI, 0.49-0.67) and for any acute tubular injury was 0.52 (95% CI, 0.45-0.58). Compared with Scr concentration, NGAL concentration demonstrated higher AUROC for diagnosing both severe acute tubular injury (0.67; 95% CI, 0.60-0.74; P=0.03) and any acute tubular injury (0.60; 95% CI, 0.55-0.66; P=0.005). In donors who did not have Scr-based AKI, NGAL concentrations were higher with increasing severities of acute tubular injury (subclinical AKI). However, compared with Scr concentration, AUROCs for acute tubular injury diagnosis were not significantly higher for urinary L

Secreted Immunomodulatory Proteins of Staphylococcus aureus Activate Platelets and Induce Platelet Aggregation.

PubMed

Binsker, Ulrike; Palankar, Raghavendra; Wesche, Jan; Kohler, Thomas P; Prucha, Josephine; Burchhardt, Gerhard; Rohde, Manfred; Schmidt, Frank; Bröker, Barbara M; Mamat, Uwe; Pané-Farré, Jan; Graf, Anica; Ebner, Patrick; Greinacher, Andreas; Hammerschmidt, Sven

2018-04-01

Staphylococcus aureus can cause bloodstream infections associated with infective endocarditis (IE) and disseminated intravascular coagulopathy (DIC). Both complications involve platelets. In view of an increasing number of antibiotic-resistant strains, new approaches to control systemic S. aureus infection are gaining importance. Using a repertoire of 52 recombinant S. aureus proteins in flow cytometry-based platelet activation and aggregation assays, we identified, in addition to the extracellular adherence protein Eap, three secreted staphylococcal proteins as novel platelet activating proteins. Eap and the chemotaxis inhibitory protein of S. aureus (CHIPS), the formyl peptide receptor-like 1 inhibitory protein (FLIPr) and the major autolysin Atl induced P-selectin expression in washed platelets and platelet-rich plasma. Similarly, AtlA, CHIPS and Eap induced platelet aggregation in whole blood. Fluorescence microscopy illustrated that P-selectin expression is associated with calcium mobilization and re-organization of the platelet actin cytoskeleton. Characterization of the functionally active domains of the major autolysin AtlA and Eap indicates that the amidase domain of Atl and the tandem repeats 3 and 4 of Eap are crucial for platelet activation. These results provide new insights in S. aureus protein interactions with platelets and identify secreted proteins as potential treatment targets in case of antibiotic-resistant S. aureus infection. Schattauer GmbH Stuttgart.

Mars Life? - Microscopic Tubular Structures

NASA Technical Reports Server (NTRS)

1996-01-01

This electron microscope image shows extremely tiny tubular structures that are possible microscopic fossils of bacteria-like organisms that may have lived on Mars more than 3.6 billion years ago. A two-year investigation by a NASA research team found organic molecules, mineral features characteristic of biological activity and possible microscopic fossils such as these inside of an ancient Martian rock that fell to Earth as a meteorite. The largest possible fossils are less than 1/100th the diameter of a human hair in size while most are ten times smaller. The fossil-like structures were found in carbonate minerals formed along pre-existing fractures in the meteorite in a fashion similar to the way fossils occur in limestone on Earth, although on a microscopic scale.

Tubular hydrogen permeable metal foil membrane and method of fabrication

DOEpatents

Paglieri, Stephen N.; Birdsell, Stephen A.; Barbero, Robert S.; Snow, Ronny C.; Smith, Frank M.

2006-04-04

A tubular hydrogen permeable metal membrane and fabrication process comprises obtaining a metal alloy foil having two surfaces, coating the surfaces with a metal or metal alloy catalytic layer to produce a hydrogen permeable metal membrane, sizing the membrane into a sheet with two long edges, wrapping the membrane around an elongated expandable rod with the two long edges aligned and overlapping to facilitate welding of the two together, placing the foil wrapped rod into a surrounding fixture housing with the two aligned and overlapping foil edges accessible through an elongated aperture in the surrounding fixture housing, expanding the elongated expandable rod within the surrounding fixture housing to tighten the foil about the expanded rod, welding the two long overlapping foil edges to one another generating a tubular membrane, and removing the tubular membrane from within the surrounding fixture housing and the expandable rod from with the tubular membrane.

Cytotoxic Activity and Antiproliferative Effects of Crude Skin Secretion from Physalaemus nattereri (Anura: Leptodactylidae) on in vitro Melanoma Cells

PubMed Central

Cruz e Carvalho, Andréa; Prías Márquez, César Augusto; Azevedo, Ricardo Bentes; Joanitti, Graziella Anselmo; Pires Júnior, Osmindo Rodrigues; Fontes, Wagner; Castro, Mariana S.

2015-01-01

Anuran secretions are rich sources of bioactive molecules, including antimicrobial and antitumoral compounds. The aims of this study were to investigate the therapeutic potential of Physalaemus nattereri skin secretion against skin cancer cells, and to assess its cytotoxic action mechanisms on the murine melanoma cell line B16F10. Our results demonstrated that the crude secretion reduced the viability of B16F10 cells, causing changes in cell morphology (e.g., round shape and structure shrinkage), reduction in mitochondrial membrane potential, increase in phosphatidylserine exposure, and cell cycle arrest in S-phase. Together, these changes suggest that tumor cells die by apoptosis. This skin secretion was also subjected to chromatographic fractioning using RP-HPLC, and eluted fractions were assayed for antiproliferative and antibacterial activities. Three active fractions showed molecular mass components in a range compatible with peptides. Although the specific mechanisms causing the reduced cell viability and cytotoxicity after the treatment with crude secretion are still unknown, it may be considered that molecules, such as the peptides found in the secretion, are effective against B16F10 tumor cells. Considering the growing need for new anticancer drugs, data presented in this study strongly reinforce the validity of P. nattereri crude secretion as a rich source of new anticancer molecules. PMID:26457717

Cytotoxic Activity and Antiproliferative Effects of Crude Skin Secretion from Physalaemus nattereri (Anura: Leptodactylidae) on in vitro Melanoma Cells.

PubMed

Cruz e Carvalho, Andréa; Márquez, César Augusto Prías; Azevedo, Ricardo Bentes; Joanitti, Graziella Anselmo; Pires Júnior, Osmindo Rodrigues; Fontes, Wagner; Castro, Mariana S

2015-10-08

Anuran secretions are rich sources of bioactive molecules, including antimicrobial and antitumoral compounds. The aims of this study were to investigate the therapeutic potential of Physalaemus nattereri skin secretion against skin cancer cells, and to assess its cytotoxic action mechanisms on the murine melanoma cell line B16F10. Our results demonstrated that the crude secretion reduced the viability of B16F10 cells, causing changes in cell morphology (e.g., round shape and structure shrinkage), reduction in mitochondrial membrane potential, increase in phosphatidylserine exposure, and cell cycle arrest in S-phase. Together, these changes suggest that tumor cells die by apoptosis. This skin secretion was also subjected to chromatographic fractioning using RP-HPLC, and eluted fractions were assayed for antiproliferative and antibacterial activities. Three active fractions showed molecular mass components in a range compatible with peptides. Although the specific mechanisms causing the reduced cell viability and cytotoxicity after the treatment with crude secretion are still unknown, it may be considered that molecules, such as the peptides found in the secretion, are effective against B16F10 tumor cells. Considering the growing need for new anticancer drugs, data presented in this study strongly reinforce the validity of P. nattereri crude secretion as a rich source of new anticancer molecules.

Mars Life? - Microscopic Tubular Structures

NASA Image and Video Library

1996-08-09

This electron microscope image shows extremely tiny tubular structures that are possible microscopic fossils of bacteria-like organisms that may have lived on Mars more than 3.6 billion years ago. http://photojournal.jpl.nasa.gov/catalog/PIA00285

Microvesicles derived from human umbilical cord mesenchymal stem cells facilitate tubular epithelial cell dedifferentiation and growth via hepatocyte growth factor induction.

PubMed

Ju, Guan-qun; Cheng, Jun; Zhong, Liang; Wu, Shuai; Zou, Xiang-yu; Zhang, Guang-yuan; Gu, Di; Miao, Shuai; Zhu, Ying-jian; Sun, Jie; Du, Tao

2015-01-01

During acute kidney injury (AKI), tubular cell dedifferentiation initiates cell regeneration; hepatocyte growth factor (HGF) is involved in modulating cell dedifferentiation. Mesenchymal stem cell (MSC)-derived microvesicles (MVs) deliver RNA into injured tubular cells and alter their gene expression, thus regenerating these cells. We boldly speculated that MVs might induce HGF synthesis via RNA transfer, thereby facilitating tubular cell dedifferentiation and regeneration. In a rat model of unilateral AKI, the administration of MVs promoted kidney recovery. One of the mechanisms of action is the acceleration of tubular cell dedifferentiation and growth. Both in vivo and in vitro, rat HGF expression in damaged rat tubular cells was greatly enhanced by MV treatment. In addition, human HGF mRNA present in MVs was delivered into rat tubular cells and translated into the HGF protein as another mechanism of HGF induction. RNase treatment abrogated all MV effects. In the in vitro experimental setting, the conditioned medium of MV-treated injured tubular cells, which contains a higher concentration of HGF, strongly stimulated cell dedifferentiation and growth, as well as Erk1/2 signaling activation. Intriguingly, these effects were completely abrogated by either c-Met inhibitor or MEK inhibitor, suggesting that HGF induction is a crucial contributor to the acceleration of cell dedifferentiation and growth. All these findings indicate that MV-induced HGF synthesis in damaged tubular cells via RNA transfer facilitates cell dedifferentiation and growth, which are important regenerative mechanisms.

Effect of Ammonia Production by Colletotrichum gloeosporioides on pelB Activation, Pectate Lyase Secretion, and Fruit Pathogenicity

PubMed Central

Kramer-Haimovich, H.; Servi, E.; Katan, T.; Rollins, J.; Okon, Y.; Prusky, D.

2006-01-01

The accumulation of ammonia and associated tissue alkalinization predispose avocado fruit to attack by Colletotrichum gloeosporioides. Secretion of ammonia by C. gloeosporioides in the presence of KNO3 was induced by decreasing the pH from 7.0 to 4.0. When the fungus was grown at pH 4.0 or 6.0 in the absence of a nitrogen source, ammonia did not accumulate, and neither pelB (encoding pectate lyase) transcription nor pectate lyase secretion was detected. Under these nitrogen starvation conditions, only transcriptional activation of areA, which encodes the global nitrogen regulator, was detected. pelB transcription and pectate lyase secretion were both detected when C. gloeosporioides was grown at pH 6.0 in the presence of ammonia accumulated from different nitrogen sources. The early accumulation of ammonia induced early pelB expression and pectate lyase secretion. As the external pH increased from 4.0 to 6.0, transcripts of pac1, the C. gloeosporioides pacC homolog, also could be detected. Nit mutants of C. gloeosporioides, which cannot utilize KNO3 as a nitrogen source, did not secrete ammonia, alkalinize the medium, or secrete pectate lyase. If Nit mutants were grown at pH 6.0 in the presence of glutamate, then pectate lyase secretion was induced. Infiltration of 0.1 M ammonium hydroxide at pH 10 into ripening avocado fruits enhanced the activation of quiescent infection and symptom development by C. gloeosporioides. These results suggest that ambient pH alkalinization resulting from ammonia accumulation and the availability of ammonia as a nitrogen source independently regulate pelB expression, pectate lyase secretion, and virulence of C. gloeosporioides. These data suggest that alkalinization during C. gloeosporioides infection is important for its transformation from the quiescent biotrophic stage to the necrotrophic stage of fungal colonization in the fruit host. PMID:16461646

Secretion of Hepatitis C Virus Replication Intermediates Reduces Activation of Toll-Like Receptor 3 in Hepatocytes.

PubMed

Grünvogel, Oliver; Colasanti, Ombretta; Lee, Ji-Young; Klöss, Volker; Belouzard, Sandrine; Reustle, Anna; Esser-Nobis, Katharina; Hesebeck-Brinckmann, Jasper; Mutz, Pascal; Hoffmann, Katrin; Mehrabi, Arianeb; Koschny, Ronald; Vondran, Florian W R; Gotthardt, Daniel; Schnitzler, Paul; Neumann-Haefelin, Christoph; Thimme, Robert; Binder, Marco; Bartenschlager, Ralf; Dubuisson, Jean; Dalpke, Alexander H; Lohmann, Volker

2018-06-01

Hepatitis C virus (HCV) infections most often result in chronic outcomes, although the virus constantly produces replication intermediates, in particular double-stranded RNA (dsRNA), representing potent inducers of innate immunity. We aimed to characterize the fate of HCV dsRNA in hepatocyte cultures to identify mechanisms contributing to viral persistence in presence of an active innate immune response. We analyzed hepatocyte-based culture models for HCV for induction of innate immunity, secretion of virus positive- or negative-strand RNA, and viral replication using different quantification methods and microscopy techniques. Expression of pattern recognition receptors was reconstituted in hepatoma cells by lentiviral transduction. HCV-infected cells secrete substantial amounts of virus positive- and negative-strand RNAs in extracellular vesicles (EVs), toward the apical and basolateral domain of hepatocytes. Secretion of negative-strand RNA was independent from virus production, and viral RNA secreted in EVs contained higher relative amounts of negative-strands, indicating that mostly virus dsRNA is released. A substantial part of viral replication complexes and dsRNA was found in the endosomal compartment and multivesicular bodies, indicating that secretion of HCV replication intermediates is mediated by the exosomal pathway. Block of vesicle release in HCV-positive cells increased intracellular dsRNA levels and increased activation of toll-like receptor 3, inhibiting HCV replication. Using hepatocyte-based culture models for HCV, we found a portion of HCV dsRNA intermediates to be released from infected cells in EVs, which reduces activation of toll-like receptor 3. This represents a novel mechanism how HCV evades host immune responses, potentially contributing to viral persistence. Copyright © 2018 AGA Institute. Published by Elsevier Inc. All rights reserved.

Peroxisome proliferator-activated receptor {alpha} agonists modulate Th1 and Th2 chemokine secretion in normal thyrocytes and Graves' disease

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

Antonelli, Alessandro, E-mail: a.antonelli@med.unipi.it; Ferrari, Silvia Martina, E-mail: sm.ferrari@int.med.unipi.it; Frascerra, Silvia, E-mail: lafrasce@gmail.com

2011-07-01

Until now, no data are present about the effect of peroxisome proliferator-activated receptor (PPAR){alpha} activation on the prototype Th1 [chemokine (C-X-C motif) ligand (CXCL)10] (CXCL10) and Th2 [chemokine (C-C motif) ligand 2] (CCL2) chemokines secretion in thyroid cells. The role of PPAR{alpha} and PPAR{gamma} activation on CXCL10 and CCL2 secretion was tested in Graves' disease (GD) and control primary thyrocytes stimulated with interferon (IFN){gamma} and tumor necrosis factor (TNF){alpha}. IFN{gamma} stimulated both CXCL10 and CCL2 secretion in primary GD and control thyrocytes. TNF{alpha} alone stimulated CCL2 secretion, while had no effect on CXCL10. The combination of IFN{gamma} and TNF{alpha} hadmore » a synergistic effect both on CXCL10 and CCL2 chemokines in GD thyrocytes at levels comparable to those of controls. PPAR{alpha} activators inhibited the secretion of both chemokines (stimulated with IFN{gamma} and TNF{alpha}) at a level higher (for CXCL10, about 60-72%) than PPAR{gamma} agonists (about 25-35%), which were confirmed to inhibit CXCL10, but not CCL2. Our data show that CCL2 is modulated by IFN{gamma} and TNF{alpha} in GD and normal thyrocytes. Furthermore we first show that PPAR{alpha} activators inhibit the secretion of CXCL10 and CCL2 in thyrocytes, suggesting that PPAR{alpha} may be involved in the modulation of the immune response in the thyroid.« less

Active and separate secretion of fiber and penton base during the early phase of Ad2 or Ad5 infection

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

Yan, Yuhua; Zhang, Bo; Hou, Weihong

Fiber and penton base overproduced in adenovirus (Ad) infected cells can be secreted prior to progeny release and thereby regulate progeny spread. We aimed to investigate the mechanisms of fiber and penton base secretion in Ad2- or Ad5-infected A549 cells. Our flow cytometry analyses detected abundant surface fiber molecules, but little penton base molecules at 12 h post infection. Immunogold staining combined with transmission electron microscopic analyses revealed separate, non-co-localized release of fiber and penton base in the proximity of the plasma membrane. Depolymerization of microtubule and actin cytoskeletons, and inhibition of Rock kinase and myosin II activity together demonstratedmore » cytoskeletal network-dependent fiber secretion. Inhibition of intracellular calcium [Ca{sup 2+}]{sub i} signaling caused diminished fiber secretion, which was associated with diminished progeny production. Thus, fiber and penton base are actively and separately secreted during the early stages of Ad2 or Ad5 infection, their secretion may play important role in Ad life cycle. - Highlights: •Excessive production of structural proteins is common to viral infection, which may regulate the host-virus equilibrium and the spreading of viruses. •The adenovirus (Ad) structural proteins, fiber and penton base, are respectively important for Ad binding to its receptor and subsequent internalization in host cells. In Ad infected cells, these two structural proteins are excessively produced. •The mechanisms underlying the release of fiber and penton base molecules at the early phase of Ad infection is yet poorly understood. •Our studies show that in Ad5 or Ad2 infected A549 cells, fiber and penton base molecules are actively and separately secreted. •Fiber secretion is dependent on cytoskeleton-mediated protein traffic. •Inhibition of myosin II motor and Ca{sup 2+} signaling activity significantly diminishes fiber secretion. •These findings could contribute to our

Palmatine, a protoberberine alkaloid, inhibits both Ca2+- and cAMP-activated Cl− secretion in isolated rat distal colon

PubMed Central

Wu, D Z; Yuan, J Y; Shi, H L; Hu, Z B

2008-01-01

Background and purpose: The protoberberine alkaloid berberine has been reported to inhibit colonic Cl− secretion. However, it is not known if other protoberberine alkaloids share these effects. We have therefore selected another protoberberine alkaloid, palmatine, to assess its effects on active ion transport across rat colonic epithelium. Experimental approach: Rat colonic mucosa was mounted in Ussing chambers and short circuit current (I SC), apical Cl− current and basolateral K+ current were recorded. Intracellular cAMP content was determined by an enzyme immunoassay. Intracellular Ca2+ concentration was measured with Fura-2 AM. Key results: Palmatine inhibited carbachol-induced Ca2+-activated Cl− secretion and the carbachol-induced increase of intracellular Ca2+ concentration. Palmatine also inhibited cAMP-activated Cl− secretion induced by prostaglandin E2 (PGE2) or forskolin. Palmatine prevented the elevation of intracellular cAMP by forskolin. Determination of apical Cl− currents showed that palmatine suppressed the forskolin-stimulated, apical cAMP-activated Cl− current but not the carbachol-stimulated apical Ca2+-activated Cl− current. Following permeabilization of apical membranes with nystatin, we found that palmatine inhibited a carbachol-stimulated basolateral K+ current that was sensitive to charybdotoxin and resistant to chromanol 293B. However, the forskolin-stimulated basolateral K+ current inhibited by palmatine was specifically blocked by chromanol 293B and not by charybdotoxin. Conclusions and implications: Palmatine attenuated Ca2+-activated Cl− secretion through inhibiting basolateral charybdotoxin-sensitive, SK4 K+ channels, whereas it inhibited cAMP-activated Cl− secretion by inhibiting apical CFTR Cl− channels and basolateral chromanol 293B-sensitive, KvLQT1 K+ channels. PMID:18204477

pH measurement of tubular vacuoles of an arbuscular mycorrhizal fungus, Gigaspora margarita.

PubMed

Funamoto, Rintaro; Saito, Katsuharu; Oyaizu, Hiroshi; Aono, Toshihiro; Saito, Masanori

2015-01-01

Arbuscular mycorrhizal fungi play an important role in phosphate supply to the host plants. The fungal hyphae contain tubular vacuoles where phosphate compounds such as polyphosphate are accumulated. Despite their importance for the phosphate storage, little is known about the physiological properties of the tubular vacuoles in arbuscular mycorrhizal fungi. As an indicator of the physiological state in vacuoles, we measured pH of tubular vacuoles in living hyphae of arbuscular mycorrhizal fungus Gigaspora margarita using ratio image analysis with pH-dependent fluorescent probe, 6-carboxyfluorescein. Fluorescent images of the fine tubular vacuoles were obtained using a laser scanning confocal microscope, which enabled calculation of vacuolar pH with high spatial resolution. The tubular vacuoles showed mean pH of 5.6 and a pH range of 5.1-6.3. These results suggest that the tubular vacuoles of arbuscular mycorrhizal fungi have a mildly acidic pH just like vacuoles of other fungal species including yeast and ectomycorrhizal fungi.

Dopamine Synthesis and D3 Receptor Activation in Pancreatic β-Cells Regulates Insulin Secretion and Intracellular [Ca2+] Oscillations

PubMed Central

Ustione, Alessandro

2012-01-01

Pancreatic islets are critical for glucose homeostasis via the regulated secretion of insulin and other hormones. We propose a novel mechanism that regulates insulin secretion from β-cells within mouse pancreatic islets: a dopaminergic negative feedback acting on insulin secretion. We show that islets are a site of dopamine synthesis and accumulation outside the central nervous system. We show that both dopamine and its precursor l-dopa inhibit glucose-stimulated insulin secretion, and this inhibition correlates with a reduction in frequency of the intracellular [Ca2+] oscillations. We further show that the effects of dopamine are abolished by a specific antagonist of the dopamine receptor D3. Because the dopamine transporter and dopamine receptors are expressed in the islets, we propose that cosecretion of dopamine with insulin activates receptors on the β-cell surface. D3 receptor activation results in changes in intracellular [Ca2+] dynamics, which, in turn, lead to lowered insulin secretion. Because blocking dopaminergic negative feedback increases insulin secretion, expanding the knowledge of this pathway in β-cells might offer a potential new target for the treatment of type 2 diabetes. PMID:22918877

Synchronous activation of gonadotropin-releasing hormone gene transcription and secretion by pulsatile kisspeptin stimulation

PubMed Central

Choe, Han Kyoung; Kim, Hee-Dae; Park, Sung Ho; Lee, Han-Woong; Park, Jae-Yong; Seong, Jae Young; Lightman, Stafford L.; Son, Gi Hoon; Kim, Kyungjin

2013-01-01

Pulsatile release of hypothalamic gonadotropin-releasing hormone (GnRH) is essential for pituitary gonadotrope function. Although the importance of pulsatile GnRH secretion has been recognized for several decades, the mechanisms underlying GnRH pulse generation in hypothalamic neural networks remain elusive. Here, we demonstrate the ultradian rhythm of GnRH gene transcription in single GnRH neurons using cultured hypothalamic slices prepared from transgenic mice expressing a GnRH promoter-driven destabilized luciferase reporter. Although GnRH promoter activity in each GnRH neuron exhibited an ultradian pattern of oscillations with a period of ∼10 h, GnRH neuronal cultures exhibited partially synchronized bursts of GnRH transcriptional activity at ∼2-h intervals. Surprisingly, pulsatile administration of kisspeptin, a potent GnRH secretagogue, evoked dramatic synchronous activation of GnRH gene transcription with robust stimulation of pulsatile GnRH secretion. We also addressed the issue of hierarchical interaction between the circadian and ultradian rhythms by using Bmal1-deficient mice with defective circadian clocks. The circadian molecular oscillator barely affected basal ultradian oscillation of GnRH transcription but was heavily involved in kisspeptin-evoked responses of GnRH neurons. In conclusion, we have clearly shown synchronous bursts of GnRH gene transcription in the hypothalamic GnRH neuronal population in association with episodic neurohormone secretion, thereby providing insight into GnRH pulse generation. PMID:23509283

Actions of Agonists and Antagonists of the ghrelin/GHS-R Pathway on GH Secretion, Appetite, and cFos Activity

PubMed Central

Hassouna, Rim; Labarthe, Alexandra; Zizzari, Philippe; Videau, Catherine; Culler, Michael; Epelbaum, Jacques; Tolle, Virginie

2012-01-01

The stimulatory effects of ghrelin, a 28-AA acylated peptide originally isolated from stomach, on growth hormone (GH) secretion and feeding are exclusively mediated through the growth hormone secretagogue 1a receptor (GHS-R1a), the only ghrelin receptor described so far. Several GHS-R1a agonists and antagonists have been developed to treat metabolic or nutritional disorders but their mechanisms of action in the central nervous system remain poorly understood. In the present study, we compared the activity of BIM-28163, a GHS-R1a antagonist, and of several agonists, including native ghrelin and the potent synthetic agonist, BIM-28131, to modulate food intake, GH secretion, and cFos activity in arcuate nucleus (ArcN), nucleus tractus solitarius (NTS), and area postrema (AP) in wild-type and NPY-GFP mice. BIM-28131 was as effective as ghrelin in stimulating GH secretion, but more active than ghrelin in inducing feeding. It stimulated cFos activity similarly to ghrelin in the NTS and AP but was more powerful in the ArcN, suggesting that the super-agonist activity of BIM-28131 is mostly mediated in the ArcN. BIM-28163 antagonized ghrelin-induced GH secretion but not ghrelin-induced food consumption and cFos activation, rather it stimulated food intake and cFos activity without affecting GH secretion. The level of cFos activation was dependent on the region considered: BIM-28163 was as active as ghrelin in the NTS, but less active in the ArcN and AP. All compounds also induced cFos immunoreactivity in ArcN NPY neurons but BIM-28131 was the most active. In conclusion, these data demonstrate that two peptide analogs of ghrelin, BIM-28163, and BIM-28131, are powerful stimulators of appetite in mice, acting through pathways and key brain regions involved in the control of appetite that are only partially superimposable from those activated by ghrelin. A better understanding of the molecular pathways activated by these compounds could be useful in devising future therapeutic

Mechanisms of bicarbonate secretion: lessons from the airways.

PubMed

Bridges, Robert J

2012-08-01

Early studies showed that airway cells secrete HCO(3)(-) in response to cAMP-mediated agonists and HCO(3)(-) secretion was impaired in cystic fibrosis (CF). Studies with Calu-3 cells, an airway serous model with high expression of CFTR, also show the secretion of HCO(3)(-) when cells are stimulated with cAMP-mediated agonists. Activation of basolateral membrane hIK-1 K(+) channels inhibits HCO(3)(-) secretion and stimulates Cl(-) secretion. CFTR mediates the exit of both HCO(3)(-) and Cl(-) across the apical membrane. Entry of HCO(3)(-) on a basolateral membrane NBC or Cl(-) on the NKCC determines which anion is secreted. Switching between these two secreted anions is determined by the activity of hIK-1 K(+) channels.

Cisplatin toxicity reduced in human cultured renal tubular cells by oxygen pretreatment.

PubMed

Kaeidi, Ayat; Rasoulian, Bahram; Hajializadeh, Zahra; Pourkhodadad, Soheila; Rezaei, Maryam

2013-01-01

Cisplatin is an effective and widely used chemotherapy agent and its side effects, particularly nephrotoxicity, limit its usage and related platinum-based drugs. Cisplatin nephrotoxicity is mainly due to extremely increase in reactive oxygen species (ROS) generation leading to kidney tubular cell death. Preconditioning with oxidative stress has been demonstrated to stimulate the cellular adaptation to subsequent severe oxidative stress. Short term oxygen pre-exposure as a mild oxidative stress may enhance some endogenous defense mechanisms, so its effect on Cisplatin induced cell death was investigated in present research. We studied the effects of hyperoxic environment pre-exposure on Cisplatin toxicity in an in-vitro model of cultured human embryonic tubular epithelial cells (AD293). Viability of AD293 cells, as evaluated by MTT-assay, was affected by Cisplatin in a time (1-4 h) dependent model. Biochemical markers of cell apoptosis were evaluated using immunoblotting. Pretreatment with nearly pure oxygen (≥90%) for 2 h significantly reduced the level of cell damage. Activated caspase 3 and Bax/Bcl-2 ratio were significantly increased in Cisplatin-treated cells. Oxygen pretreatment inhibited caspase 3 activation and decreased Bax/Bcl-2 ratio. Oxygen pre-treatment itself not showed any cytotoxicity in exposure times up to 3 h. Our data indicate that hyperoxic preconditioning reduces Cisplatin toxicity in cultured human tubular epithelial cells. The exact mechanism of protection is unclear, though enhancement of some endogenous defense mechanisms and subsequently scavenging of free oxygen radicals may play an important role.

Tubular solid oxide fuel cell current collector

DOEpatents

Bischoff, Brian L.; Sutton, Theodore G.; Armstrong, Timothy R.

2010-07-20

An internal current collector for use inside a tubular solid oxide fuel cell (TSOFC) electrode comprises a tubular coil spring disposed concentrically within a TSOFC electrode and in firm uniform tangential electrical contact with the electrode inner surface. The current collector maximizes the contact area between the current collector and the electrode. The current collector is made of a metal that is electrically conductive and able to survive under the operational conditions of the fuel cell, i.e., the cathode in air, and the anode in fuel such as hydrogen, CO, CO.sub.2, H.sub.2O or H.sub.2S.

Influence of deoxynivalenol on NF-kappaB activation and IL-8 secretion in human intestinal Caco-2 cells.

PubMed

Van De Walle, Jacqueline; Romier, Béatrice; Larondelle, Yvan; Schneider, Yves-Jacques

2008-04-01

Deoxynivalenol (DON) is the most prevalent trichothecene mycotoxin in crops in Europe and North America. In human intestinal Caco-2 cells, DON activates the mitogen-activated protein kinases (MAPKs). We hypothesized a link between DON ingestion and intestinal inflammation, and used Caco-2 cells to assess the effects of DON, at plausible intestinal concentrations (250-10,000 ng/ml), on inflammatory mediators acting downstream the MAPKs cascade i.e. activation of nuclear factor-kappaB (NF-kappaB) and interleukin-8 (IL-8) secretion. In addition, Caco-2 cells were co-exposed to pro-inflammatory stimuli in order to mimic an inflamed intestinal epithelium. Dose-dependent increases in NF-kappaB activity and IL-8 secretion were observed, reaching 1.4- and 7.6-fold, respectively using DON at 10 microg/ml. Phosphorylation of inhibitor-kappaB (IkappaB) increased (1.6-fold) at DON levels <0.5 microg/ml. Exposure of Caco-2 cells to pro-inflammatory agents, i.e. 25 ng/ml interleukin-1beta, 100 ng/ml tumor necrosis factor-alpha or 10 microg/ml lipopolysaccharides, activated NF-kappaB and increased IL-8 secretion. Synergistic interactions between these stimuli and DON were observed. These data show that DON induces NF-kappaB activation and IL-8 secretion dose-dependently in Caco-2 cells, and this effect was accentuated upon pro-inflammatory stimulation, suggesting DON exposure could cause or exacerbate intestinal inflammation.

Rilmenidine sympatholytic activity preserves mental stress, orthostatic sympathetic responses and adrenaline secretion.

PubMed

Esler, Murray; Lux, Alan; Jennings, Garry; Hastings, Jacqui; Socratous, Flora; Lambert, Gavin

2004-08-01

Heightened central sympathetic nervous outflow is common in essential hypertension, contributing to hypertension development and possibly also to complications. Acute sympathetic nervous activation is a proven trigger for adverse cardiovascular events. Accordingly, antihypertensive drugs inhibiting sympathetic outflow represent a theoretically attractive therapeutic option. To study the sympatholytic and blood pressure-lowering activity of the imidazoline binding agent rilmenidine at rest and during reflex sympathetic activation. We used a randomized, double-blind, 6-week cross-over study, with a 1-week placebo run-in period, two 2-week active treatment intervals (rilmenidine 1 mg twice daily or placebo) and intervening 1-week placebo washout. In 15 hypertensive patients, noradrenaline and adrenaline plasma kinetics and intra-arterial blood pressure measurements were performed at rest, after mental stress (difficult mental arithmetic) and during head-up tilting, at the end of the 2-week dosing periods. The noradrenaline spillover rate, indicative of whole body sympathetic activity, was reduced 35% by rilmenidine at rest (P < 0.01) and remained significantly lower during mental stress and tilting, although the increases in noradrenaline spillover with both stimuli were preserved. The effects on intra-arterial blood pressure ran in parallel, a fall in supine resting pressure, but no reduction in blood pressure rise during mental stress and a lack of fall in blood pressure with tilting. On placebo, adrenaline secretion was 0.88 +/- 0.15 nmol/min (mean +/- SE) at rest, increased by 0.42 +/- 0.23 nmol/min with mental stress (P = 0.019) and was unchanged with tilting. Rilmenidine left adrenaline secretion untouched under all conditions. The present study confirms a sympatholytic effect of rilmenidine during supine rest but preservation of sympathetic responses during mental stress and tilting, with the latter underlying a freedom from postural hypotension on the drug

A novel mechanism by which hepatocyte growth factor blocks tubular epithelial to mesenchymal transition.

PubMed

Yang, Junwei; Dai, Chunsun; Liu, Youhua

2005-01-01

Hepatocyte growth factor (HGF) is a potent antifibrotic cytokine that blocks tubular epithelial to mesenchymal transition (EMT) induced by TGF-beta1. However, the underlying mechanism remains largely unknown. This study investigated the signaling events that lead to HGF blockade of the TGF-beta1-initiated EMT. Incubation of human kidney epithelial cells HKC with HGF only marginally affected the expression of TGF-beta1 and its type I and type II receptors, suggesting that disruption of TGF-beta1 signaling likely plays a critical role in mediating HGF inhibition of TGF-beta1 action. However, HGF neither affected TGF-beta1-induced Smad-2 phosphorylation and its subsequent nuclear translocation nor influenced the expression of inhibitory Smad-6 and -7 in tubular epithelial cells. HGF specifically induced the expression of Smad transcriptional co-repressor SnoN but not Ski and TG-interacting factor at both mRNA and protein levels in HKC cells. SnoN physically interacted with activated Smad-2 by forming transcriptionally inactive complex and overrode the profibrotic action of TGF-beta1. In vivo, HGF did not affect Smad-2 activation and its nuclear accumulation in tubular epithelium, but it restored SnoN protein abundance in the fibrotic kidney in obstructive nephropathy. Hence, HGF blocks EMT by antagonizing TGF-beta1's action via upregulating Smad transcriptional co-repressor SnoN expression. These findings not only identify a novel mode of interaction between the signals activated by HGF receptor tyrosine kinase and TGF-beta receptor serine/threonine kinases but also illustrate the feasibility of confining Smad activity as an effective strategy for blocking renal fibrosis.

Bcl-2 protects tubular epithelial cells from ischemia/reperfusion injury by dual mechanisms.

PubMed

Isaka, Y; Suzuki, C; Abe, T; Okumi, M; Ichimaru, N; Imamura, R; Kakuta, Y; Matsui, I; Takabatake, Y; Rakugi, H; Shimizu, S; Takahara, S

2009-01-01

Ischemia/reperfusion (I/R) injury, which induces extensive loss of tubular epithelial cells, is associated with delayed graft function following kidney transplantation. Recent reports have suggested that cell death by I/R injury occurs by autophagy, a cellular degradation process responsible for the turnover of unnecessary or dysfunctional organelles and cytoplasmic proteins, as well as by apoptosis. Recently, we demonstrated that overexpression of the anti-apoptotic factor, Bcl-2, inhibited tubular apoptosis and subsequent tubulointerstitial damage after I/R injury. Autophagy is also observed in cells undergoing cell death in several diseases. Therefore, we hypothesized that increased Bcl-2 protein may protect tubular epithelial cells by suppressing autophagy and inhibiting apoptosis. In the present study, a transgenic mouse model (LC3-GFP TG) in which autophagosomes are labeled with LC3-GFP and Bcl-2/LC3-GFP double transgenic mice (Bcl-2/LC3-GFP TG) were used to examine the effect of Bcl-2 on I/R-induced autophagy. I/R injury, which is associated with marked disruption of normal tubular morphology, promoted the formation of LC3-GFP dots, representing extensively induced autophagosomes. On electron microscopy, the autophagosomes contained mitochondria in I/R-injured tubular epithelial cells. In contrast, Bcl-2 augmentation suppressed the formation of autophagosomes and there was less tubular damage. In conclusion, Bcl-2 augmentation protected renal tubular epithelial cells from I/R injury by suppressing autophagosomal degradation and inhibiting tubular apoptosis.

Active secretion and protective effect of salivary nitrate against stress in human volunteers and rats

PubMed Central

Jin, Luyuan; Qin, Lizheng; Xia, Dengsheng; Liu, Xibao; Fan, Zhipeng; Zhang, Chunmei; Gu, Liankun; He, Junqi; Ambudkar, Indu S.; Deng, Dajun; Wang, Songlin

2014-01-01

Up to 25% of the circulating nitrate in blood is actively taken up, concentrated, and secreted into saliva by the salivary glands. Salivary nitrate can be reduced to nitrite by the commensal bacteria in the oral cavity or stomach and then further converted to nitric oxide (NO) in vivo, which may play a role in gastric protection. However, whether salivary nitrate is actively secreted in human beings has not yet been determined. This study was designed to determine whether salivary nitrate is actively secreted in human beings as an acute stress response and what role salivary nitrate plays in stress-induced gastric injury. To observe salivary nitrate function under stress conditions, alteration of salivary nitrate and nitrite was analyzed among 22 healthy volunteers before and after a strong stress activity, jumping down from a platform at the height of 68m. A series of stress indexes was analyzed to monitor the stress situation. We found that both the concentration and the total amount of nitrate in mixed saliva were significantly increased in the human volunteers immediately after the jump, with an additional increase 1 h later (p < 0.01). Saliva nitrite reached a maximum immediately after the jump and was maintained 1 h later. To study the biological functions of salivary nitrate and nitrite in stress protection, we further carried out a water-immersion-restraint stress (WIRS) assay in male adult rats with bilateral parotid and submandibular duct ligature (BPSDL). Intragastric nitrate, nitrite, and NO; gastric mucosal blood flow; and gastric ulcer index (UI) were monitored and nitrate was administrated in drinking water to compensate for nitrate secretion in BPSDL animals. Significantly decreased levels of intragastric nitrate, nitrite, and NO and gastricmucosal blood flow were measured in BPSDL rats during the WIRS assay compared to sham control rats (p < 0.05). Recovery was observed in the BPSDL rats upon nitrate administration. The WIRS-induced UI was

Expression of cleaved caspase-3 in renal tubular cells in Plasmodium falciparum malaria patients.

PubMed

Wichapoon, Benjamas; Punsawad, Chuchard; Viriyavejakul, Parnpen

2017-01-01

In Plasmodium falciparum malaria, the clinical manifestation of acute kidney injury (AKI) is commonly associated with acute tubular necrosis (ATN) in the kidney tissues. Renal tubular cells often exhibit various degrees of cloudy swelling, cell degeneration, and frank necrosis. To study individual cell death, this study evaluates the degree of renal tubular necrosis in association with apoptosis in malarial kidneys. Kidney tissues from P. falciparum malaria with AKI (10 cases), and without AKI (10 cases) were evaluated for tubular pathology. Normal kidney tissues from 10 cases served as controls. Tubular necrosis was assessed quantitatively in kidney tissues infected with P. falciparum malaria, based on histopathological evaluation. In addition, the occurrence of apoptosis was investigated using cleaved caspase-3 marker. Correlation between tubular necrosis and apoptosis was analyzed. Tubular necrosis was found to be highest in P. falciparum malaria patients with AKI (36.44% ± 3.21), compared to non-AKI (15.88% ± 1.63) and control groups (2.58% ± 0.39) (all p < 0.001). In the AKI group, the distal tubules showed a significantly higher degree of tubular necrosis than the proximal tubules (p = 0.021) and collecting tubules (p = 0.033). Tubular necrosis was significantly correlated with the level of serum creatinine (r = 0.596, p = 0.006), and the occurrence of apoptosis (r = 0.681, p = 0.001). In malarial AKI, the process of apoptosis occurs in ATN. © 2016 Asian Pacific Society of Nephrology.

[Clonal association of flat epithelial atypia and tubular breast cancer].

PubMed

Aulmann, S; Elsawaf, Z; Penzel, R; Schirmacher, P; Sinn, H P

2008-11-01

Flat epithelial atypia (FEA) of the breast has recently gained attention as a possible precursor lesion of highly differentiated breast cancer. Especially tubular carcinomas, with which FEA shares cytological features, often occur in close proximity to each other. To examine a possible clonal relationship, we analysed mutations of the highly variable region of the mitochondrial genome in a series of tubular carcinomas, associated FEA and normal glands. Multiple sequence alignment showed identical mtDNA mutations in approximately 50% of paired FEA and tumour samples, indicative of a clonal relationship. Our data indicate a possible precursor role of FEA in the development of tubular breast cancer.

Distal Renal Tubular Acidosis and Calcium Nephrolithiasis

NASA Astrophysics Data System (ADS)

Moe, Orson W.; Fuster, Daniel G.; Xie, Xiao-Song

2008-09-01

Calcium stones are commonly encountered in patients with congenital distal renal tubular acidosis, a disease of renal acidification caused by mutations in either the vacuolar H+-ATPase (B1 or a4 subunit), anion exchanger-1, or carbonic anhydrase II. Based on the existing database, we present two hypotheses. First, heterozygotes with mutations in B1 subunit of H+-ATPase are not normal but may harbor biochemical abnormalities such as renal acidification defects, hypercalciuria, and hypocitraturia which can predispose them to kidney stone formation. Second, we propose at least two mechanisms by which mutant B1 subunit can impair H+-ATPase: defective pump assembly and defective pump activity.

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.

Tubular Adenoma of the Breast: A Rare Presentation and Review of the Literature

PubMed Central

Salemis, Nikolaos S.; Gemenetzis, Georgios; Karagkiouzis, Gregorios; Seretis, Charalambos; Sapounas, Konstantinos; Tsantilas, Vlasios; Sambaziotis, Dimitrios; Lagoudianakis, Emmanuel

2012-01-01

Tubular adenomas, also known as pure adenomas, are rare epithelial tumors of the breast. Only a few cases have been reported in the literature, especially in young women of reproductive age. Postmenopausal women are very rarely affected. We describe here a very rare case of tubular breast adenoma in a postmenopausal woman who presented with a gradually enlarging breast lump. Clinical examination and imaging studies revealed a non-tender well circumscribed left breast tumor suggestive of a fibroadenoma. Due to the history of progressive enlargement of the breast lump, a surgical excision was performed. Histological findings were suggestive of a tubular breast adenoma. We conclude that although tubular breast adenoma is rare, it should always be considered in the differential diagnosis in postmenopausal patients presenting with a gradually enlarging breast mass. Preoperative diagnosis is difficult because tubular adenoma is indistinguishable from a fibroadenoma on physical examination and breast imaging. Surgical excision is necessary to establish a definitive diagnosis. Clinical presentation and management of our patient are discussed along with a review of the literature. Keywords Tubular adenoma; Breast; Breast mass. PMID:22383931

Tubular adenoma of the breast: a rare presentation and review of the literature.

PubMed

Salemis, Nikolaos S; Gemenetzis, Georgios; Karagkiouzis, Gregorios; Seretis, Charalambos; Sapounas, Konstantinos; Tsantilas, Vlasios; Sambaziotis, Dimitrios; Lagoudianakis, Emmanuel

2012-02-01

Tubular adenomas, also known as pure adenomas, are rare epithelial tumors of the breast. Only a few cases have been reported in the literature, especially in young women of reproductive age. Postmenopausal women are very rarely affected. We describe here a very rare case of tubular breast adenoma in a postmenopausal woman who presented with a gradually enlarging breast lump. Clinical examination and imaging studies revealed a non-tender well circumscribed left breast tumor suggestive of a fibroadenoma. Due to the history of progressive enlargement of the breast lump, a surgical excision was performed. Histological findings were suggestive of a tubular breast adenoma. We conclude that although tubular breast adenoma is rare, it should always be considered in the differential diagnosis in postmenopausal patients presenting with a gradually enlarging breast mass. Preoperative diagnosis is difficult because tubular adenoma is indistinguishable from a fibroadenoma on physical examination and breast imaging. Surgical excision is necessary to establish a definitive diagnosis. Clinical presentation and management of our patient are discussed along with a review of the literature. Tubular adenoma; Breast; Breast mass.

Conazole fungicides inhibit Leydig cell testosterone secretion and androgen receptor activation in vitro.

PubMed

Roelofs, Maarke J E; Temming, A Roberto; Piersma, Aldert H; van den Berg, Martin; van Duursen, Majorie B M

2014-01-01

Conazole fungicides are widely used in agriculture despite their suspected endocrine disrupting properties. In this study, the potential (anti-)androgenic effects of ten conazoles were assessed and mutually compared with existing data. Effects of cyproconazole (CYPRO), fluconazole (FLUC), flusilazole (FLUS), hexaconazole (HEXA), myconazole (MYC), penconazole (PEN), prochloraz (PRO), tebuconazole (TEBU), triadimefon (TRIA), and triticonazole (TRIT) were examined using murine Leydig (MA-10) cells and human T47D-ARE cells stably transfected with an androgen responsive element and a firefly luciferase reporter gene. Six conazoles caused a decrease in basal testosterone (T) secretion by MA-10 cells varying from 61% up to 12% compared to vehicle-treated control. T secretion was concentration-dependently inhibited after exposure of MA-10 cells to several concentrations of FLUS (IC 50 = 12.4 μM) or TEBU (IC 50 = 2.4 μM) in combination with LH. The expression of steroidogenic and cholesterol biosynthesis genes was not changed by conazole exposure. Also, there were no changes in reactive oxygen species (ROS) formation that could explain the altered T secretion after exposure to conazoles. Nine conazoles decreased T-induced AR activation (IC 50 s ranging from 10.7 to 71.5 μM) and effect potencies (REPs) were calculated relative to the known AR antagonist flutamide (FLUT). FLUC had no effect on AR activation by T. FLUS was the most potent (REP = 3.61) and MYC the least potent (REP = 0.03) AR antagonist. All other conazoles had a comparable REP from 0.12 to 0.38. Our results show distinct in vitro anti-androgenic effects of several conazole fungicides arising from two mechanisms: inhibition of T secretion and AR antagonism, suggesting potential testicular toxic effects. These effects warrant further mechanistic investigation and clearly show the need for accurate exposure data in order to perform proper (human) risk assessment of this class of compounds.

A Simple Tubular Reactor Experiment.

ERIC Educational Resources Information Center

Hudgins, Robert R.; Cayrol, Bertrand

1981-01-01

Using the hydrolysis of crystal violet dye by sodium hydroxide as an example, the theory, apparatus, and procedure for a laboratory demonstration of tubular reactor behavior are described. The reaction presented can occur at room temperature and features a color change to reinforce measured results. (WB)

Factor h and properdin recognize different epitopes on renal tubular epithelial heparan sulfate.

PubMed

Zaferani, Azadeh; Vivès, Romain R; van der Pol, Pieter; Navis, Gerjan J; Daha, Mohamed R; van Kooten, Cees; Lortat-Jacob, Hugues; Seelen, Marc A; van den Born, Jacob

2012-09-07

During proteinuria, renal tubular epithelial cells become exposed to ultrafiltrate-derived serum proteins, including complement factors. Recently, we showed that properdin binds to tubular heparan sulfates (HS). We now document that factor H also binds to tubular HS, although to a different epitope than properdin. Factor H was present on the urinary side of renal tubular cells in proteinuric, but not in normal renal tissues and colocalized with properdin in proteinuric kidneys. Factor H dose-dependently bound to proximal tubular epithelial cells (PTEC) in vitro. Preincubation of factor H with exogenous heparin and pretreatment of PTECs with heparitinase abolished the binding to PTECs. Surface plasmon resonance experiments showed high affinity of factor H for heparin and HS (K(D) values of 32 and 93 nm, respectively). Using a library of HS-like polysaccharides, we showed that chain length and high sulfation density are the most important determinants for glycosaminoglycan-factor H interaction and clearly differ from properdin-heparinoid interaction. Coincubation of properdin and factor H did not hamper HS/heparin binding of one another, indicating recognition of different nonoverlapping epitopes on HS/heparin by factor H and properdin. Finally we showed that certain low anticoagulant heparinoids can inhibit properdin binding to tubular HS, with a minor effect on factor H binding to tubular HS. As a result, these heparinoids can control the alternative complement pathway. In conclusion, factor H and properdin interact with different HS epitopes of PTECs. These interactions can be manipulated with some low anticoagulant heparinoids, which can be important for preventing complement-derived tubular injury in proteinuric renal diseases.

Quercetin induces insulin secretion by direct activation of L-type calcium channels in pancreatic beta cells

PubMed Central

Bardy, G; Virsolvy, A; Quignard, J F; Ravier, M A; Bertrand, G; Dalle, S; Cros, G; Magous, R; Richard, S; Oiry, C

2013-01-01

Background and Purpose Quercetin is a natural polyphenolic flavonoid that displays anti-diabetic properties in vivo. Its mechanism of action on insulin-secreting beta cells is poorly documented. In this work, we have analysed the effects of quercetin both on insulin secretion and on the intracellular calcium concentration ([Ca2+]i) in beta cells, in the absence of any co-stimulating factor. Experimental Approach Experiments were performed on both INS-1 cell line and rat isolated pancreatic islets. Insulin release was quantified by the homogeneous time-resolved fluorescence method. Variations in [Ca2+]i were measured using the ratiometric fluorescent Ca2+ indicator Fura-2. Ca2+ channel currents were recorded with the whole-cell patch-clamp technique. Key Results Quercetin concentration-dependently increased insulin secretion and elevated [Ca2+]i. These effects were not modified by the SERCA inhibitor thapsigargin (1 μmol·L−1), but were nearly abolished by the L-type Ca2+ channel antagonist nifedipine (1 μmol·L−1). Similar to the L-type Ca2+ channel agonist Bay K 8644, quercetin enhanced the L-type Ca2+ current by shifting its voltage-dependent activation towards negative potentials, leading to the increase in [Ca2+]i and insulin secretion. The effects of quercetin were not inhibited in the presence of a maximally active concentration of Bay K 8644 (1 μmol·L−1), with the two drugs having cumulative effects on [Ca2+]i. Conclusions and Implications Taken together, our results show that quercetin stimulates insulin secretion by increasing Ca2+ influx through an interaction with L-type Ca2+ channels at a site different from that of Bay K 8644. These data contribute to a better understanding of quercetin's mechanism of action on insulin secretion. PMID:23530660

Lipoxin A4 activates ALX/FPR2 receptor to regulate conjunctival goblet cell secretion.

PubMed

Hodges, R R; Li, D; Shatos, M A; Bair, J A; Lippestad, M; Serhan, C N; Dartt, D A

2017-01-01

Conjunctival goblet cells play a major role in maintaining the mucus layer of the tear film under physiological conditions as well as in inflammatory diseases like dry eye and allergic conjunctivitis. Resolution of inflammation is mediated by proresolution agonists such as lipoxin A 4 (LXA 4 ) that can also function under physiological conditions. The purpose of this study was to determine the actions of LXA 4 on cultured rat conjunctival goblet cell mucin secretion, intracellular [Ca 2+ ] ([Ca 2+ ] i ), and identify signaling pathways activated by LXA 4 . ALX/FPR2 (formyl peptide receptor2) was localized to goblet cells in rat conjunctiva and in cultured goblet cells. LXA 4 significantly increased mucin secretion, [Ca 2+ ] i , and extracellular regulated kinase 1/2 (ERK 1/2) activation. These functions were inhibited by ALX/FPR2 inhibitors. Stable analogs of LXA 4 increased [Ca 2+ ] i to the same extent as LXA 4 . Sequential addition of either LXA 4 or resolvin D1 followed by the second compound decreased [Ca 2+ ] i of the second compound compared with its initial response. LXA 4 activated phospholipases C, D, and A 2 and downstream molecules protein kinase C, ERK 1/2, and Ca 2+ /calmodulin-dependent kinase to increase mucin secretion and [Ca 2+ ] i . We conclude that conjunctival goblet cells respond to LXA 4 to maintain the homeostasis of the ocular surface and could be a novel treatment for dry eye diseases.

Lipoxin A4 activates ALX/FPR2 Receptor to Regulate Conjunctival Goblet Cell Secretion

PubMed Central

Hodges, Robin R.; Li, Dayu; Shatos, Marie A.; Bair, Jeffrey A.; Lippestad, Marit; Serhan, Charles N.; Dartt, Darlene A.

2016-01-01

Conjunctival goblet cells play a major role in maintaining the mucous layer of the tear film under physiological conditions as well as in inflammatory diseases like dry eye and allergic conjunctivitis.. Resolution of inflammation is mediated by pro-resolution agonists such as lipoxin A4 (LXA4) that can also function under physiological conditions. The purpose of this study was to determine the actions of LXA4 on cultured rat conjunctival goblet cell mucin secretion, intracellular [Ca2+] ([Ca2+]i) and identify signaling pathways activated by LXA4. ALX/FPR was localized to goblet cells in rat conjunctiva and in cultured goblet cells. LXA4 significantly increased mucin secretion, [Ca2+]i, and ERK 1/2 activation. These functions were inhibited by ALX/FPR2 inhibitors. Stable analogs of LXA4 increased [Ca2+]i to the same extent as LXA4. Sequential addition of either LXA4 or resolvin D1 followed by the second compound decreased [Ca2+]i of the second compound compared to its initial response. LXA4 activated phospholipase C, -D, and A2 and downstream molecules protein kinase C, ERK 1/2, and Ca2+/calmodulin dependent kinase to increase mucin secretion and [Ca2+]i. We conclude that conjunctival goblet cells respond to LXA4 to maintain the homeostasis of the ocular surface and could be a novel treatment for dry eye diseases. PMID:27072607

Genetics Home Reference: renal tubular dysgenesis

MedlinePlus

... genetic condition? Genetic and Rare Diseases Information Center Frequency Renal tubular dysgenesis is a rare disorder, but ... of Medicine Lister Hill National Center for Biomedical Communications 8600 Rockville Pike, Bethesda, MD 20894, USA HONCode ...

Temperature oscillations drive cycles in the activity of MMP-2,9 secreted by a human trabecular meshwork cell line.

PubMed

Li, Stanley Ka-Lok; Banerjee, Juni; Jang, Christopher; Sehgal, Amita; Stone, Richard A; Civan, Mortimer M

2015-02-05

Aqueous humor inflow falls 50% during sleeping hours without proportional fall in IOP, partly reflecting reduced outflow facility. The mechanisms underlying outflow facility cycling are unknown. One outflow facility regulator is matrix metalloproteinase (MMP) release from trabecular meshwork (TM) cells. Because anterior segment temperature must oscillate due to core temperature cycling and eyelid closure during sleep, we tested whether physiologically relevant temperature oscillations drive cycles in the activity of secreted MMP. Temperature of transformed normal human TM cells (hTM5 line) was fixed or alternated 12 hours/12 hours between 33°C and 37°C. Activity of secreted MMP-2 and MMP-9 was measured by zymography, and gene expression by RT-PCR and quantitative PCR. Raising temperature to 37°C increased, and lowering to 33°C reduced, activity of secreted MMP. Switching between 37°C and 33°C altered MMP-9 by 40% ± 3% and MMP-2 by 22% ± 2%. Peripheral circadian clocks did not mediate temperature-driven cycling of MMP secretion because MMP-release oscillations did not persist at constant temperature after 3 to 6 days of alternating temperatures, and temperature cycles did not entrain clock-gene expression in these cells. Furthermore, inhibiting heat shock transcription factor 1, which links temperature and peripheral clock-gene oscillations, inhibited MMP-9 but not MMP-2 temperature-driven MMP cycling. Inhibition of heat-sensitive TRPV1 channels altered total MMP secretion but not temperature-induced modulations. Inhibiting cold-sensitive TRPM-8 channels had no effect. Physiologically relevant temperature oscillations drive fluctuations of secreted MMP-2 and MMP-9 activity in hTM5 cells independent of peripheral clock genes and temperature-sensitive TRP channels. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.

Genetics Home Reference: tubular aggregate myopathy

MedlinePlus

... in both type I and type II fibers, forming clumps of tube-like structures called tubular aggregates. ... Hyun C, Woo JS, Park CS, Kim do H, Lee EH. Stromal interaction molecule 1 (STIM1) regulates ...

Bubble-Free Propulsion of Ultrasmall Tubular Nanojets Powered by Biocatalytic Reactions.

PubMed

Ma, Xing; Hortelao, Ana C; Miguel-López, Albert; Sánchez, Samuel

2016-10-26

The motion of self-propelled tubular micro- and nanojets has so far been achieved by bubble propulsion, e.g., O 2 bubbles formed by catalytic decomposition of H 2 O 2 , which renders future biomedical applications inviable. An alternative self-propulsion mechanism for tubular engines on the nanometer scale is still missing. Here, we report the fabrication and characterization of bubble-free propelled tubular nanojets (as small as 220 nm diameter), powered by an enzyme-triggered biocatalytic reaction using urea as fuel. We studied the translational and rotational dynamics of the nanojets as functions of the length and location of the enzymes. Introducing tracer nanoparticles into the system, we demonstrated the presence of an internal flow that extends into the external fluid via the cavity opening, leading to the self-propulsion. One-dimensional nanosize, longitudinal self-propulsion, and biocompatibility make the tubular nanojets promising for future biomedical applications.

Antibody-Mediated Activation of FGFR1 Induces FGF23 Production and Hypophosphatemia

PubMed Central

Kolumam, Ganesh; Zavala-Solorio, Jose; Wyatt, Shelby K.; Gandham, Vineela D.; Carano, Richard A. D.; Sonoda, Junichiro

2013-01-01

The phosphaturic hormone Fibroblast Growth Factor 23 (FGF23) controls phosphate homeostasis by regulating renal expression of sodium-dependent phosphate co-transporters and cytochrome P450 enzymes involved in vitamin D catabolism. Multiple FGF Receptors (FGFRs) can act as receptors for FGF23 when bound by the co-receptor Klotho expressed in the renal tubular epithelium. FGFRs also regulate skeletal FGF23 secretion; ectopic FGFR activation is implicated in genetic conditions associated with FGF23 overproduction and hypophosphatemia. The identity of FGFRs that mediate the activity of FGF23 or that regulate skeletal FGF23 secretion remains ill defined. Here we report that pharmacological activation of FGFR1 with monoclonal anti-FGFR1 antibodies (R1MAb) in adult mice is sufficient to cause an elevation in serum FGF23 and mild hypophosphatemia. In cultured rat calvariae osteoblasts, R1MAb induces FGF23 mRNA expression and FGF23 protein secretion into the culture medium. In a cultured kidney epithelial cell line, R1MAb acts as a functional FGF23 mimetic and activates the FGF23 program. siRNA-mediated Fgfr1 knockdown induced the opposite effects. Taken together, our work reveals the central role of FGFR1 in the regulation of FGF23 production and signal transduction, and has implications in the pathogenesis of FGF23-related hypophosphatemic disorders. PMID:23451204

Pneumolysin-Dependent Calpain Activation and Interleukin-1α Secretion in Macrophages Infected with Streptococcus pneumoniae.

PubMed

Fang, Rendong; Wu, Rui; Du, Huihui; Jin, Meilan; Liu, Yajing; Lei, Guihua; Jiang, Bing; Lei, Zehui; Peng, Yuanyi; Nie, Kui; Tsuchiya, Kohsuke

2017-09-01

Pneumolysin (PLY), a major virulence factor of Streptococcus pneumoniae , is a pore-forming cytolysin that modulates host innate responses contributing to host defense against and pathogenesis of pneumococcal infections. Interleukin-1α (IL-1α) has been shown to be involved in tissue damage in a pneumococcal pneumonia model; however, the mechanism by which this cytokine is produced during S. pneumoniae infection remains unclear. In this study, we examined the role of PLY in IL-1α production. Although the strains induced similar levels of pro-IL-1α expression, wild-type S. pneumoniae D39, but not a deletion mutant of the ply gene (Δ ply ), induced the secretion of mature IL-1α from host macrophages, suggesting that PLY is critical for the maturation and secretion of IL-1α during S. pneumoniae infection. Further experiments with calcium chelators and calpain inhibitors indicated that extracellular calcium ions and calpains (calcium-dependent proteases) facilitated the maturation and secretion of IL-1α from D39-infected macrophages. Moreover, we found that PLY plays a critical role in calcium influx and calpain activation, as elevated intracellular calcium levels and the degradation of the calpain substrate α-fodrin were detected in macrophages infected with D39 but not the Δ ply strain. These results suggested that PLY induces the influx of calcium in S. pneumoniae -infected macrophages, followed by calpain activation and subsequent IL-1α maturation and secretion. Copyright © 2017 American Society for Microbiology.

Plant flavones enhance antimicrobial activity of respiratory epithelial cell secretions against Pseudomonas aeruginosa

PubMed Central

Hariri, Benjamin M.; McMahon, Derek B.; Chen, Bei; Adappa, Nithin D.; Palmer, James N.; Kennedy, David W.

2017-01-01

Flavones are a class of natural plant secondary metabolites that have anti-inflammatory and anti-bacterial effects. Some flavones also activate the T2R14 bitter taste receptor, which is expressed in motile cilia of the sinonasal epithelium and activates innate immune nitric oxide (NO) production. Flavones may thus be potential therapeutics for respiratory infections. Our objective was to examine the anti-microbial effects of flavones on the common sinonasal pathogens Candida albicans, Staphylococcus aureus, and Pseudomonas aeruginosa, evaluating both planktonic and biofilm growth. Flavones had only very low-level antibacterial activity alone. They did not reduce biofilm formation, but did reduce production of the important P. aeruginosa inflammatory mediator and ciliotoxin pyocyanin. However, flavones exhibited synergy against P. aeruginosa in the presence of antibiotics or recombinant human lysozyme. They also enhanced the efficacy of antimicrobials secreted by cultured and primary human airway cells grown at air-liquid interface. This suggests that flavones may have anti-gram-negative potential as topical therapeutics when combined with antibiotics or in the context of innate antimicrobials secreted by the respiratory or other epithelia. This may have an additive effect when combined with T2R14-activated NO production. Additional studies are necessary to understand which flavone compounds or mixtures are the most efficacious. PMID:28931063

Heme induces IL-1β secretion through activating NLRP3 in kidney inflammation.

PubMed

Li, Qianwei; Fu, Weihua; Yao, Jiwei; Ji, Zheng; Wang, Yongquan; Zhou, Zhansong; Yan, Junan; Li, Weibing

2014-07-01

To produce proinflammatory master cytokine IL-1β in macrophages, two stimulation pathways are needed including TLRs-NF-κB axis and NLRPs/ASC-caspase-1 axis. Different signals including exogenous and endogenous trigger inflammatory response distinctly. Among them, the role of endogenous stimulators of inflammation is poorly understood. As a component of hemoglobin, free heme is released when hemolysis or extensive cell damage occur which results in inflammatory response. Here, we find that heme induces IL-1β secretion through activating NLRP3 inflammasome in macrophages. Heme activates NLRP3 through P2X receptors, especially the P2X7R and P2X4R. Most importantly, significantly enhancement of heme level and activation of NLRPs/ASC-caspase-1 axis were observed in mice kidney after unilateral ureteral obstruction which could be inhibited by enforced expression of heme oxygenase-1 (HO-1). Our study proves that heme is a potential danger activator of NLRP3 inflammasome that plays an essential role in IL-1β secretion during kidney inflammation and provides new insight into the mechanism of innate immune initiation. Further investigation will be beneficial to develop new molecular target and molecular diagnosis indicator in therapy of kidney inflammation.

Interferon-γ Reduces the Proliferation of Primed Human Renal Tubular Cells.

PubMed

García-Sánchez, Omar; López-Novoa, José Miguel; López-Hernández, Francisco J

2014-01-01

Chronic kidney disease (CKD) is a progressive deterioration of the kidney function, which may eventually lead to renal failure and the need for dialysis or kidney transplant. Whether initiated in the glomeruli or the tubuli, CKD is characterized by progressive nephron loss, for which the process of tubular deletion is of key importance. Tubular deletion results from tubular epithelial cell death and defective repair, leading to scarring of the renal parenchyma. Several cytokines and signaling pathways, including transforming growth factor-β (TGF-β) and the Fas pathway, have been shown to participate in vivo in tubular cell death. However, there is some controversy about their mode of action, since a direct effect on normal tubular cells has not been demonstrated. We hypothesized that epithelial cells would require specific priming to become sensitive to TGF-β or Fas stimulation and that this priming would be brought about by specific mediators found in the pathological scenario. Herein we studied whether the combined effect of several stimuli known to take part in CKD progression, namely TGF-β, tumor necrosis factor-α, interferon-γ (IFN-γ), and Fas stimulation, on primed resistant human tubular cells caused cell death or reduced proliferation. We demonstrate that these cytokines have no synergistic effect on the proliferation or viability of human kidney (HK2) cells. We also demonstrate that IFN-γ, but not the other stimuli, reduces the proliferation of cycloheximide-primed HK2 cells without affecting their viability. Our results point at a potentially important role of IFN-γ in defective repair, leading to nephron loss during CKD.

Insulin secretion and its association with physical activity, fitness and screen time in children.

PubMed

Henderson, M; Gray-Donald, K; Rabasa-Lhoret, R; Bastard, J-P; Barnett, T A; Benedetti, A; Chaput, J-P; Tremblay, A; Lambert, M

2014-02-01

To determine the independent associations of moderate to vigorous physical activity (MVPA), fitness, screen time, and adiposity with insulin secretion in children. Caucasian youth (n = 423/630), 8-10 years old, with at least one obese biological parent, were studied (QUALITY cohort). Insulin secretion was measured using HOMA2-%B, area under the curve (AUC) of insulin to glucose over the first 30 minutes (AUC I/G(t30min)) of the OGTT and AUC I/G(t120min) over 2 hours. Fitness was measured by VO₂peak ; percent fat mass (PFM) by DXA; 7-day MVPA by accelerometry; self-reported screen time included television, video game, or computer use. Models were adjusted for age, sex, season, puberty, PFM, and insulin sensitivity [IS] (HOMA2-IS, Matsuda-ISI). PFM was strongly associated with insulin secretion, even after adjustment for IS: for every 1% increase in PFM, insulin secretion increased from 0.3% to 0.8% across indices. MVPA was negatively associated with HOMA2-%B (P < 0.05), but not with OGTT-derived measures. Fitness was negatively associated with AUC I/G(t120min) (P < 0.05). Screen time showed a trend toward higher HOMA2-%B in girls (P = 0.060). In children with an obese parent, lower insulin secretion is associated with lower adiposity, higher MVPA, better fitness, and possibly reduced screen time. Copyright © 2013 The Obesity Society.

An Intracellular Peptidyl-Prolyl cis/trans Isomerase Is Required for Folding and Activity of the Staphylococcus aureus Secreted Virulence Factor Nuclease.

PubMed

Wiemels, Richard E; Cech, Stephanie M; Meyer, Nikki M; Burke, Caleb A; Weiss, Andy; Parks, Anastacia R; Shaw, Lindsey N; Carroll, Ronan K

2017-01-01

Staphylococcus aureus is an important human pathogen that relies on a large repertoire of secreted and cell wall-associated proteins for pathogenesis. Consequently, the ability of the organism to cause disease is absolutely dependent on its ability to synthesize and successfully secrete these proteins. In this study, we investigate the role of peptidyl-prolyl cis/trans isomerases (PPIases) on the activity of the S. aureus secreted virulence factor nuclease (Nuc). We identify a staphylococcal cyclophilin-type PPIase (PpiB) that is required for optimal activity of Nuc. Disruption of ppiB results in decreased nuclease activity in culture supernatants; however, the levels of Nuc protein are not altered, suggesting that the decrease in activity results from misfolding of Nuc in the absence of PpiB. We go on to demonstrate that PpiB exhibits PPIase activity in vitro, is localized to the bacterial cytosol, and directly interacts with Nuc in vitro to accelerate the rate of Nuc refolding. Finally, we demonstrate an additional role for PpiB in S. aureus hemolysis and demonstrate that the S. aureus parvulin-type PPIase PrsA also plays a role in the activity of secreted virulence factors. The deletion of prsA leads to a decrease in secreted protease and phospholipase activity, similar to that observed in other Gram-positive pathogens. Together, these results demonstrate, for the first time to our knowledge, that PPIases play an important role in the secretion of virulence factors in S. aureus IMPORTANCE: Staphylococcus aureus is a highly dangerous bacterial pathogen capable of causing a variety of infections throughout the human body. The ability of S. aureus to cause disease is largely due to an extensive repertoire of secreted and cell wall-associated proteins, including adhesins, toxins, exoenzymes, and superantigens. These virulence factors, once produced, are typically transported across the cell membrane by the secretory (Sec) system in a denatured state. Consequently

Activation of intestinal Cl- secretion by lubiprostone requires the cystic fibrosis transmembrane conductance regulator.

PubMed

Bijvelds, Marcel J C; Bot, Alice G M; Escher, Johanna C; De Jonge, Hugo R

2009-09-01

Lubiprostone alleviates constipation by stimulating intestinal fluid secretion, purportedly through activation of ClC-2-type Cl(-) channels. Intestinal obstruction is also a recurrent cause of distress in cystic fibrosis (CF) patients, caused by loss of CF transmembrane conductance regulator (CFTR) Cl(-) channel activity. Because ClC-2 recruitment might be beneficial to CF patients, we investigated lubiprostone's mode of action. Cl(-) transport was measured in an Ussing chamber, in 3 model systems: (1) T84 colonocytes, (2) intestinal epithelium of wild-type and CF mice, and (3) intestinal epithelium of CF patients and controls. In T84 monolayers, lubiprostone induced a robust secretory response. Selective permeabilization of the basolateral plasma membrane revealed that lubiprostone activated an apical Cl(-) conductance. The lubiprostone response was attenuated by H89, an inhibitor of the cAMP-dependent protein kinase, and lubiprostone precluded responsiveness to the cAMP agonist forskolin. CFTR blockage by CFTRinh172, but not ClC-2 blockage by CdCl(2), inhibited the lubiprostone response. Lubiprostone induced a CdCl(2)-insensitive secretory response in mouse intestine, but failed to induce intestinal Cl(-) secretion in Cftr-null mice. Correspondingly, lubiprostone induced a secretory response in human intestinal epithelium, but not in tissue of CF patients. The EP(4)-type prostanoid receptor antagonist L-161,982 blocked the lubiprostone response in all 3 models studied. In T84 cells, lubiprostone induced a rise in cAMP levels that was sensitive to EP(4)-receptor blockage. Lubiprostone enhances intestinal Cl(-) and fluid secretion via prostanoid receptor signaling, triggering activation of CFTR. Therefore, it is of limited use for treatment of CF-related intestinal disease.

Dental Calculus Stimulates Interleukin-1β Secretion by Activating NLRP3 Inflammasome in Human and Mouse Phagocytes

PubMed Central

Montenegro Raudales, Jorge Luis; Yoshimura, Atsutoshi; SM, Ziauddin; Kaneko, Takashi; Ozaki, Yukio; Ukai, Takashi; Miyazaki, Toshihiro; Latz, Eicke; Hara, Yoshitaka

2016-01-01

Dental calculus is a mineralized deposit associated with periodontitis. The bacterial components contained in dental calculus can be recognized by host immune sensors, such as Toll-like receptors (TLRs), and induce transcription of proinflammatory cytokines, such as IL-1β. Studies have shown that cellular uptake of crystalline particles may trigger NLRP3 inflammasome activation, leading to the cleavage of the IL-1β precursor to its mature form. Phagocytosis of dental calculus in the periodontal pocket may therefore lead to the secretion of IL-1β, promoting inflammatory responses in periodontal tissues. However, the capacity of dental calculus to induce IL-1β secretion in human phagocytes has not been explored. To study this, we stimulated human polymorphonuclear leukocytes (PMNs) and peripheral blood mononuclear cells (PBMCs) with dental calculus collected from periodontitis patients, and measured IL-1β secretion by ELISA. We found that calculus induced IL-1β secretion in both human PMNs and PBMCs. Calculus also induced IL-1β in macrophages from wild-type mice, but not in macrophages from NLRP3- and ASC-deficient mice, indicating the involvement of NLRP3 and ASC. IL-1β induction was inhibited by polymyxin B, suggesting that LPS is one of the components of calculus that induces pro-IL-1β transcription. To analyze the effect of the inorganic structure, we baked calculus at 250°C for 1 h. This baked calculus failed to induce pro-IL-1β transcription. However, it did induce IL-1β secretion in lipid A-primed cells, indicating that the crystalline structure of calculus induces inflammasome activation. Furthermore, hydroxyapatite crystals, a component of dental calculus, induced IL-1β in mouse macrophages, and baked calculus induced IL-1β in lipid A-primed human PMNs and PBMCs. These results indicate that dental calculus stimulates IL-1β secretion via NLRP3 inflammasome in human and mouse phagocytes, and that the crystalline structure has a partial role in

Dental Calculus Stimulates Interleukin-1β Secretion by Activating NLRP3 Inflammasome in Human and Mouse Phagocytes.

PubMed

Montenegro Raudales, Jorge Luis; Yoshimura, Atsutoshi; Sm, Ziauddin; Kaneko, Takashi; Ozaki, Yukio; Ukai, Takashi; Miyazaki, Toshihiro; Latz, Eicke; Hara, Yoshitaka

2016-01-01

Dental calculus is a mineralized deposit associated with periodontitis. The bacterial components contained in dental calculus can be recognized by host immune sensors, such as Toll-like receptors (TLRs), and induce transcription of proinflammatory cytokines, such as IL-1β. Studies have shown that cellular uptake of crystalline particles may trigger NLRP3 inflammasome activation, leading to the cleavage of the IL-1β precursor to its mature form. Phagocytosis of dental calculus in the periodontal pocket may therefore lead to the secretion of IL-1β, promoting inflammatory responses in periodontal tissues. However, the capacity of dental calculus to induce IL-1β secretion in human phagocytes has not been explored. To study this, we stimulated human polymorphonuclear leukocytes (PMNs) and peripheral blood mononuclear cells (PBMCs) with dental calculus collected from periodontitis patients, and measured IL-1β secretion by ELISA. We found that calculus induced IL-1β secretion in both human PMNs and PBMCs. Calculus also induced IL-1β in macrophages from wild-type mice, but not in macrophages from NLRP3- and ASC-deficient mice, indicating the involvement of NLRP3 and ASC. IL-1β induction was inhibited by polymyxin B, suggesting that LPS is one of the components of calculus that induces pro-IL-1β transcription. To analyze the effect of the inorganic structure, we baked calculus at 250°C for 1 h. This baked calculus failed to induce pro-IL-1β transcription. However, it did induce IL-1β secretion in lipid A-primed cells, indicating that the crystalline structure of calculus induces inflammasome activation. Furthermore, hydroxyapatite crystals, a component of dental calculus, induced IL-1β in mouse macrophages, and baked calculus induced IL-1β in lipid A-primed human PMNs and PBMCs. These results indicate that dental calculus stimulates IL-1β secretion via NLRP3 inflammasome in human and mouse phagocytes, and that the crystalline structure has a partial role in

Developmental changes in renal tubular transport - An overview

PubMed Central

Gattineni, Jyothsna; Baum, Michel

2013-01-01

The adult kidney maintains a constant volume and composition of extracellular fluid despite changes in water and salt intake. The neonate is born with a kidney that has a small fraction of the glomerular filtration rate of the adult and immature tubules that function at a lower capacity than that of the mature animal. None the less, the neonate is also able to maintain a constant extracellular fluid volume and composition. Postnatal renal tubular development was once thought to be due to an increase in the transporter abundance to meet the developmental increase in glomerular filtration rate. However, postnatal renal development of each nephron segment is quite complex. There are isoform changes of several transporters as well as developmental changes in signal transduction that affect the capacity of renal tubules to reabsorb solutes and water. This review will discuss neonatal tubular function with an emphasis on the differences that have been found between the neonate and adult. We will also discuss some of the factors that are responsible for the maturational changes in tubular transport that occur during postnatal renal development. PMID:24253590

Developmental changes in renal tubular transport-an overview.

PubMed

Gattineni, Jyothsna; Baum, Michel

2015-12-01

The adult kidney maintains a constant volume and composition of extracellular fluid despite changes in water and salt intake. The neonate is born with a kidney that has a small fraction of the glomerular filtration rate of the adult and immature tubules that function at a lower capacity than that of the mature animal. Nonetheless, the neonate is also able to maintain a constant extracellular fluid volume and composition. Postnatal renal tubular development was once thought to be due to an increase in the transporter abundance to meet the developmental increase in glomerular filtration rate. However, postnatal renal development of each nephron segment is quite complex. There are isoform changes of several transporters as well as developmental changes in signal transduction that affect the capacity of renal tubules to reabsorb solutes and water. This review will discuss neonatal tubular function with an emphasis on the differences that have been found between the neonate and adult. We will also discuss some of the factors that are responsible for the maturational changes in tubular transport that occur during postnatal renal development.

Fusion-activated cation entry (FACE) via P2X₄ couples surfactant secretion and alveolar fluid transport.

PubMed

Thompson, Kristin E; Korbmacher, Jonas P; Hecht, Elena; Hobi, Nina; Wittekindt, Oliver H; Dietl, Paul; Kranz, Christine; Frick, Manfred

2013-04-01

Two fundamental mechanisms within alveoli are essential for lung function: regulated fluid transport and secretion of surfactant. Surfactant is secreted via exocytosis of lamellar bodies (LBs) in alveolar type II (ATII) cells. We recently reported that LB exocytosis results in fusion-activated cation entry (FACE) via P2X₄ receptors on LBs. We propose that FACE, in addition to facilitating surfactant secretion, modulates alveolar fluid transport. Correlative fluorescence and atomic force microscopy revealed that FACE-dependent water influx correlated with individual fusion events in rat primary ATII cells. Moreover, ATII cell monolayers grown at air-liquid interface exhibited increases in short-circuit current (Isc) on stimulation with ATP or UTP. Both are potent agonists for LB exocytosis, but only ATP activates FACE. ATP, not UTP, elicited additional fusion-dependent increases in Isc. Overexpressing dominant-negative P2X₄ abrogated this effect by ∼50%, whereas potentiating P2X4 lead to ∼80% increase in Isc. Finally, we monitored changes in alveolar surface liquid (ASL) on ATII monolayers by confocal microscopy. Only stimulation with ATP, not UTP, led to a significant, fusion-dependent, 20% decrease in ASL, indicating apical-to-basolateral fluid transport across ATII monolayers. Our data support the first direct link between LB exocytosis, regulation of surfactant secretion, and transalveolar fluid resorption via FACE.

Boron--epoxy tubular structure members

NASA Technical Reports Server (NTRS)

Shakespeare, W. B. J.; Nelson, P. T.; Lindkvist, E. C.

1973-01-01

Composite materials fabricate thin-walled tubular members which have same load-carrying capabilities as aluminum, titanium, or other metals, but are lighter. Interface between stepped end fitting and tube lends itself to attachments by primary as well as secondary bonding. Interlaminar shear and hoop stress buildup in attachment at end fitting is avoided.

Method and tool for contracting tubular members by electro-hydraulic forming before hydroforming

DOEpatents

Golovashchenko, Sergey Fedorovich [Beverly Hills, MI

2011-03-15

A tubular preform is contracted in an electro-hydraulic forming operation. The tubular preform is wrapped with one or more coils of wire and placed in a chamber of an electro-hydraulic forming tool. The electro-hydraulic forming tool is discharged to form a compressed area on a portion of the tube. The tube is then placed in a hydroforming tool that expands the tubular preform to form a part.

Interferon-γ Reduces the Proliferation of Primed Human Renal Tubular Cells

PubMed Central

García-Sánchez, Omar; López-Novoa, José Miguel; López-Hernández, Francisco J.

2014-01-01

Background/Aims Chronic kidney disease (CKD) is a progressive deterioration of the kidney function, which may eventually lead to renal failure and the need for dialysis or kidney transplant. Whether initiated in the glomeruli or the tubuli, CKD is characterized by progressive nephron loss, for which the process of tubular deletion is of key importance. Tubular deletion results from tubular epithelial cell death and defective repair, leading to scarring of the renal parenchyma. Several cytokines and signaling pathways, including transforming growth factor-β (TGF-β) and the Fas pathway, have been shown to participate in vivo in tubular cell death. However, there is some controversy about their mode of action, since a direct effect on normal tubular cells has not been demonstrated. We hypothesized that epithelial cells would require specific priming to become sensitive to TGF-β or Fas stimulation and that this priming would be brought about by specific mediators found in the pathological scenario. Methods Herein we studied whether the combined effect of several stimuli known to take part in CKD progression, namely TGF-β, tumor necrosis factor-α, interferon-γ (IFN-γ), and Fas stimulation, on primed resistant human tubular cells caused cell death or reduced proliferation. Results We demonstrate that these cytokines have no synergistic effect on the proliferation or viability of human kidney (HK2) cells. We also demonstrate that IFN-γ, but not the other stimuli, reduces the proliferation of cycloheximide-primed HK2 cells without affecting their viability. Conclusion Our results point at a potentially important role of IFN-γ in defective repair, leading to nephron loss during CKD. PMID:24575118

Normal tubular regeneration and differentiation of the post-ischemic kidney in mice lacking vimentin.

PubMed Central

Terzi, F.; Maunoury, R.; Colucci-Guyon, E.; Babinet, C.; Federici, P.; Briand, P.; Friedlander, G.

1997-01-01

Proliferation and dedifferentiation of tubular cells are the hallmark of early regeneration after renal ischemic injury. Vimentin, a class III intermediate filament expressed only in mesenchymal cells of mature mammals, was shown to be transiently expressed in post-ischemic renal tubular epithelial cells. Vimentin re-expression was interpreted as a marker of cellular dedifferentiation, but its role in tubular regeneration after renal ischemia has also been hypothesized. This role was evaluated in mice bearing a null mutation of the vimentin gene. Expression of vimentin, proliferating cell nuclear antigen (a marker of cellular proliferation), and villin (a marker of differentiated brush-border membranes) was studied in wild-type (Vim+/+), heterozygous (Vim+/-), and homozygous (Vim-/-) mice subjected to transient ischemia of the left kidney. As expected, vimentin was detected by immunohistochemistry at the basal pole of proximal tubular cells from post-ischemic kidney in Vim+/+ and Vim+/- mice from day 2 to day 28. The expression of the reporter gene beta-galactosidase in Vim+/- and Vim-/- mice confirmed the tubular origin of vimentin. No compensatory expression of keratin could be demonstrated in Vim-/- mice. The intensity of proliferating cell nuclear antigen labeling and the pattern of villin expression were comparable in Vim-/-, Vim+/- and Vim+/+ mice at any time of the study. After 60 days, the structure of post-ischemic kidneys in Vim-/- mice was indistinguishable from that of normal non-operated kidneys in Vim+/+ mice. In conclusion, 1) the pattern of post-ischemic proximal tubular cell proliferation, differentiation, and tubular organization was not impaired in mice lacking vimentin and 2) these results suggest that the transient tubular expression of vimentin is not instrumental in tubular regeneration after renal ischemic injury. Images Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 Figure 7 PMID:9094992

Review: peripheral nerve regeneration using non-tubular alginate gel crosslinked with covalent bonds.

PubMed

Hashimoto, Tadashi; Suzuki, Yoshihisa; Suzuki, Kyoko; Nakashima, Toshihide; Tanihara, Masao; Ide, Chizuka

2005-06-01

We have developed a nerve regeneration material consisting of alginate gel crosslinked with covalent bonds. in the first part of this study, we attempted to analyze nerve regeneration through alginate gel in the early stages within 2 weeks. in the second part, we tried to regenerate cat peripheral nerve by using alginate tubular or non-tubular nerve regeneration devices, and compared their efficacies. Four days after surgery, regenerating axons grew without Schwann cell investment through the partially degraded alginate gel, being in direct contact with the alginate without a basal lamina covering. One to 2 weeks after surgery, regenerating axons were surrounded by common Schwann cells, forming small bundles, with some axons at the periphery being partly in direct contact with alginate. At the distal stump, numerous Schwann cells had migrated into the alginate 8-14 days after surgery. Remarkable restorations of the 50-mm gap in cat sciatic nerve were obtained after a long term by using tubular or non-tubular nerve regeneration material consisting mainly of alginate gel. However, there was no significant difference between both groups at electrophysiological and morphological evaluation. Although, nowadays, nerve regeneration materials being marketed mostly have a tubular structure, our results suggest that the tubular structure is not indispensable for peripheral nerve regeneration.

Antimicrobial activity of the pygidial gland secretion of three ground beetle species (Insecta: Coleoptera: Carabidae)

NASA Astrophysics Data System (ADS)

Nenadić, Marija; Soković, Marina; Glamočlija, Jasmina; Ćirić, Ana; Perić-Mataruga, Vesna; Ilijin, Larisa; Tešević, Vele; Vujisić, Ljubodrag; Todosijević, Marina; Vesović, Nikola; Ćurčić, Srećko

2016-04-01

The antimicrobial properties of the pygidial gland secretions released by the adults of the three ground beetle species, Carabus ullrichii, C. coriaceus, and Abax parallelepipedus, have been tested. Microdilution method was applied for detection of minimal inhibitory concentrations (MICs), minimal bactericidal concentrations (MBCs), and minimal fungicidal concentrations (MFCs). Additionally, morpho-histology of the pygidial glands is investigated. We have tested 16 laboratory and clinical strains of human pathogens—eight bacterial both gram-positive and gram-negative species and eight fungal species. The pygidial secretion samples of C. ullrichii have showed the strongest antimicrobial effect against all strains of treated bacteria and fungi. Staphylococcus aureus, Lysteria monocytogenes, and Salmonella typhimurium proved to be the most sensitive bacterial strains. Penicillium funiculosum proved to be the most sensitive micromycete, while P. ochrochloron and P. verrucosum var . cyclopium the most resistant micromycetes. The pygidial secretion of C. coriaceus has showed antibacterial potential solely against Pseudomonas aeruginosa and antifungal activity against Aspergillus fumigatus, A. versicolor, A. ochraceus, and P. ochrochloron. Antibacterial properties of pygidial gland secretion of A. parallelepipedus were achieved against P. aeruginosa, while antifungal activity was detected against five of the eight tested micromycetes (A. fumigatus, A. versicolor, A. ochraceus, Trichoderma viride, and P. verrucosum var . cyclopium). Commercial antibiotics Streptomycin and Ampicillin and mycotics Ketoconazole and Bifonazole, applied as the positive controls, showed higher antibacterial/antifungal properties for all bacterial and fungal strains. The results of this observation might have a significant impact on the environmental aspects and possible medical purpose in the future.

Tubular Tissues and Organs of Human Body--Challenges in Regenerative Medicine.

PubMed

Góra, Aleksander; Pliszka, Damian; Mukherjee, Shayanti; Ramakrishna, Seeram

2016-01-01

Tissue engineering of tubular organs such as the blood vessel, trachea gastrointestinal tract, urinary tract are of the great interest due to the high amount of surgeries performed annually on those organs. Development in tissue engineering in recent years and promising results, showed need to investigate more complex constructs that need to be designed in special manner. Stent technology remain the most widely used procedure to restore functions of tubular tissues after cancer treatment, or after organ removal due to traumatic accidents. Tubular structures like blood vessels, intestines, and trachea have to work in specific environment at the boundary of the liquids, solids or air and surrounding tissues and ensure suitable separation between them. This brings additional challenges in tissue engineering science in order to construct complete organs by using combinations of various cells along with the support material systems. Here we give a comprehensive review of the tubular structures of the human body, in perspective of the current methods of treatment and progress in regenerative medicine that aims to develop fully functioning organs of tubular shape. Extensive analysis of the available literature has been done focusing on materials and methods of creations of such organs. This work describes the attempts to incorporate growth factors and drugs within the scaffolds to ensure localized drug release and enhance vascularization of the organ by attracting blood vessels to the site of implantation.

Activity of Genital Tract Secretions and Synthetic Antimicrobial Peptides against Group B Streptococcus.

PubMed

Agarwal, Nidhi; Buckley, Niall; Nakra, Natasha; Gialanella, Philip; Yuan, Weirong; Ghartey, Jeny P

2015-12-01

Genital tract secretions inhibit Escherichia coli (E. coli) through antimicrobial peptides (AMP) secreted by the host and vaginal microbiota. However, there are limited data against group B Streptococcus (GBS). Group B Streptococcus were incubated with cervico-vaginal lavage (CVL) samples from healthy non-pregnant women (n = 12) or synthetic AMP and monitored for bacterial growth using a turbidimetric approach. E. coli inhibitory activity was determined by a colony-forming unit assay. None of the CVL samples inhibited GBS. The human neutrophil peptide-1 and human defensin 5 inhibited GBS growth by ≥80% at concentrations ≥20 μg/mL and ≥50 μg/mL, respectively, while human beta-defensin 2 and LL-37 did not inhibit at highest concentration tested (100 μg/mL). In contrast, all AMP inhibited E. coli. Antimicrobial peptides may protect against E. coli colonization but have more limited activity against GBS. Future studies will focus on augmenting host defense with specific AMP to prevent genitourinary infection with these pathogenic organisms. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Adapting Active Shape Models for 3D segmentation of tubular structures in medical images.

PubMed

de Bruijne, Marleen; van Ginneken, Bram; Viergever, Max A; Niessen, Wiro J

2003-07-01

Active Shape Models (ASM) have proven to be an effective approach for image segmentation. In some applications, however, the linear model of gray level appearance around a contour that is used in ASM is not sufficient for accurate boundary localization. Furthermore, the statistical shape model may be too restricted if the training set is limited. This paper describes modifications to both the shape and the appearance model of the original ASM formulation. Shape model flexibility is increased, for tubular objects, by modeling the axis deformation independent of the cross-sectional deformation, and by adding supplementary cylindrical deformation modes. Furthermore, a novel appearance modeling scheme that effectively deals with a highly varying background is developed. In contrast with the conventional ASM approach, the new appearance model is trained on both boundary and non-boundary points, and the probability that a given point belongs to the boundary is estimated non-parametrically. The methods are evaluated on the complex task of segmenting thrombus in abdominal aortic aneurysms (AAA). Shape approximation errors were successfully reduced using the two shape model extensions. Segmentation using the new appearance model significantly outperformed the original ASM scheme; average volume errors are 5.1% and 45% respectively.

VCP-dependent muscle degeneration is linked to defects in a dynamic tubular lysosomal network in vivo

PubMed Central

Johnson, Alyssa E; Shu, Huidy; Hauswirth, Anna G; Tong, Amy; Davis, Graeme W

2015-01-01

Lysosomes are classically viewed as vesicular structures to which cargos are delivered for degradation. Here, we identify a network of dynamic, tubular lysosomes that extends throughout Drosophila muscle, in vivo. Live imaging reveals that autophagosomes merge with tubular lysosomes and that lysosomal membranes undergo extension, retraction, fusion and fission. The dynamics and integrity of this tubular lysosomal network requires VCP, an AAA-ATPase that, when mutated, causes degenerative diseases of muscle, bone and neurons. We show that human VCP rescues the defects caused by loss of Drosophila VCP and overexpression of disease relevant VCP transgenes dismantles tubular lysosomes, linking tubular lysosome dysfunction to human VCP-related diseases. Finally, disruption of tubular lysosomes correlates with impaired autophagosome-lysosome fusion, increased cytoplasmic poly-ubiquitin aggregates, lipofuscin material, damaged mitochondria and impaired muscle function. We propose that VCP sustains sarcoplasmic proteostasis, in part, by controlling the integrity of a dynamic tubular lysosomal network. DOI: http://dx.doi.org/10.7554/eLife.07366.001 PMID:26167652

A narrow open tubular column for high efficiency liquid chromatographic separation

DOE PAGES

Chen, Huang; Yang, Yu; Qiao, Zhenzhen; ...

2018-01-01

We report a great feature of open tubular liquid chromatography when it is run using an extremely narrow ( e.g. , 2 μm inner diameter) open tubular column: more than 10 million plates per meter can be achieved in less than 10 min and under an elution pressure of ca. 20 bar.

A narrow open tubular column for high efficiency liquid chromatographic separation

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

Chen, Huang; Yang, Yu; Qiao, Zhenzhen

We report a great feature of open tubular liquid chromatography when it is run using an extremely narrow ( e.g. , 2 μm inner diameter) open tubular column: more than 10 million plates per meter can be achieved in less than 10 min and under an elution pressure of ca. 20 bar.

Emergent patterns of collective cell migration under tubular confinement.

PubMed

Xi, Wang; Sonam, Surabhi; Beng Saw, Thuan; Ladoux, Benoit; Teck Lim, Chwee

2017-11-15

Collective epithelial behaviors are essential for the development of lumens in organs. However, conventional assays of planar systems fail to replicate cell cohorts of tubular structures that advance in concerted ways on out-of-plane curved and confined surfaces, such as ductal elongation in vivo. Here, we mimic such coordinated tissue migration by forming lumens of epithelial cell sheets inside microtubes of 1-10 cell lengths in diameter. We show that these cell tubes reproduce the physiological apical-basal polarity, and have actin alignment, cell orientation, tissue organization, and migration modes that depend on the extent of tubular confinement and/or curvature. In contrast to flat constraint, the cell sheets in a highly constricted smaller microtube demonstrate slow motion with periodic relaxation, but fast overall movement in large microtubes. Altogether, our findings provide insights into the emerging migratory modes for epithelial migration and growth under tubular confinement, which are reminiscent of the in vivo scenario.

HER-2 amplification in tubular carcinoma of the breast.

PubMed

Oakley, Gerard J; Tubbs, Raymond R; Crowe, Joseph; Sebek, Bruce; Budd, G Thomas; Patrick, Rebecca J; Procop, Gary W

2006-07-01

The prognostic and therapeutic implications of HER-2 gene amplification and estrogen and progesterone receptor status in breast cancer are well described. To address the relative paucity of information concerning HER-2 amplification for tubular carcinomas, we assessed the frequency of gene amplification in 55 tubular carcinomas of the breast from 54 patients, 5 of which had axillary node metastases. The HER-2 gene copy number was assessed by fluorescence in situ hybridization for the majority of tumors analyzed, whereas estrogen and progesterone receptor status was achieved by immunohistochemical analysis. HER-2 gene amplification was not observed in any of the tumors examined, and most were estrogen receptor-positive. This HER-2 gene amplification frequency was significantly lower than the frequency of gene amplification previously reported for all invasive ductal carcinoma of no special type (P < .01). HER-2 gene amplification likely occurs infrequently, or not at all, in tubular carcinomas of the breast, whereas most express estrogen receptors.

Characterization of Organic Anion Transporter 2 (SLC22A7): A Highly Efficient Transporter for Creatinine and Species-Dependent Renal Tubular Expression.

PubMed

Shen, Hong; Liu, Tongtong; Morse, Bridget L; Zhao, Yue; Zhang, Yueping; Qiu, Xi; Chen, Cliff; Lewin, Anne C; Wang, Xi-Tao; Liu, Guowen; Christopher, Lisa J; Marathe, Punit; Lai, Yurong

2015-07-01

The contribution of organic anion transporter OAT2 (SLC22A7) to the renal tubular secretion of creatinine and its exact localization in the kidney are reportedly controversial. In the present investigation, the transport of creatinine was assessed in human embryonic kidney (HEK) cells that stably expressed human OAT2 (OAT2-HEK) and isolated human renal proximal tubule cells (HRPTCs). The tubular localization of OAT2 in human, monkey, and rat kidney was characterized. The overexpression of OAT2 significantly enhanced the uptake of creatinine in OAT2-HEK cells. Under physiologic conditions (creatinine concentrations of 41.2 and 123.5 µM), the initial rate of OAT2-mediated creatinine transport was approximately 11-, 80-, and 80-fold higher than OCT2, multidrug and toxin extrusion protein (MATE)1, and MATE2K, respectively, resulting in approximately 37-, 1850-, and 80-fold increase of the intrinsic transport clearance when normalized to the transporter protein concentrations. Creatinine intracellular uptake and transcellular transport in HRPTCs were decreased in the presence of 50 µM bromosulfophthalein and 100 µM indomethacin, which inhibited OAT2 more potently than other known creatinine transporters, OCT2 and multidrug and toxin extrusion proteins MATE1 and MATE2K (IC50: 1.3 µM vs. > 100 µM and 2.1 µM vs. > 200 µM for bromosulfophthalein and indomethacin, respectively) Immunohistochemistry analysis showed that OAT2 protein was localized to both basolateral and apical membranes of human and cynomolgus monkey renal proximal tubules, but appeared only on the apical membrane of rat proximal tubules. Collectively, the findings revealed the important role of OAT2 in renal secretion and possible reabsorption of creatinine and suggested a molecular basis for potential species difference in the transporter handling of creatinine. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Small-molecule activators of TMEM16A, a calcium-activated chloride channel, stimulate epithelial chloride secretion and intestinal contraction

PubMed Central

Namkung, Wan; Yao, Zhen; Finkbeiner, Walter E.; Verkman, A. S.

2011-01-01

TMEM16A (ANO1) is a calcium-activated chloride channel (CaCC) expressed in secretory epithelia, smooth muscle, and other tissues. Cell-based functional screening of ∼110,000 compounds revealed compounds that activated TMEM16A CaCC conductance without increasing cytoplasmic Ca2+. By patch-clamp, N-aroylaminothiazole “activators” (Eact) strongly increased Cl− current at 0 Ca2+, whereas tetrazolylbenzamide “potentiators” (Fact) were not active at 0 Ca2+ but reduced the EC50 for Ca2+-dependent TMEM16A activation. Of 682 analogs tested, the most potent activator (Eact) and potentiator (Fact) produced large and more sustained CaCC Cl− currents than general agonists of Ca2+ signaling, with EC50 3–6 μM and Cl− conductance comparable to that induced transiently by Ca2+-elevating purinergic agonists. Analogs of activators were identified that fully inhibited TMEM16A Cl− conductance, providing further evidence for direct TMEM16A binding. The TMEM16A activators increased CaCC conductance in human salivary and airway submucosal gland epithelial cells, and IL-4 treated bronchial cells, and stimulated submucosal gland secretion in human bronchi and smooth muscle contraction in mouse intestine. Small-molecule, TMEM16A-targeted activators may be useful for drug therapy of cystic fibrosis, dry mouth, and gastrointestinal hypomotility disorders, and for pharmacological dissection of TMEM16A function.—Namkung, W., Yao, Z., Finkbeiner, W. E., Verkman, A. S. Small-molecule activators of TMEM16A, a calcium-activated chloride channel, stimulate epithelial chloride secretion and intestinal contraction. PMID:21836025

The fine structure of sheep myocardial cells; sarcolemmal invaginations and the transverse tubular system.

PubMed

SIMPSON, F O; OERTELIS, S J

1962-01-01

An electron microscope study of sheep myocardial cells has demonstrated the presence of a transverse tubular system, apparently forming a network across the cell at each Z band level. The walls of these tubules resemble the sarcolemma in consisting of two dense layers-plasma membrane and basement menbrane; continuity of the tubule walls with the sarcolemma can be seen when longitudinal sections of a cell are obtained between two subsarcolemmal myofibrils and at the same time perpendicular to the cell surface. The demonstration of communication between the lumen of the transverse tubular system and the extracellular space appears to be more definite in this study than in any work hitherto published. It provides anatomical evidence of a possible direct pathway for transmission of the activating impulse from the sarcolemma to the myofibril Z bands.

Dietary monosodium glutamate enhances gastric secretion.

PubMed

Khropycheva, Raisa; Uneyama, Hisayuki; Torii, Kunio; Zolotarev, Vasiliy

2009-01-01

Dietary L-glutamate (Glu), an amino acid abundant in many foodstuffs in a free form, is able to modulate physiological functions in the stomach, including secretion and motility. Recently, specific receptors for Glu were identified in the apical membrane of chief cells in the lower region of fundic glands and in the somatostatin-secreting D-cell fraction of the gastric mucosa. This Glu-sensing system in the stomach is linked to activation of the vagal afferents. Among 20 kinds of amino acid, luminal Glu alone activated the vagal afferents in the stomach through a paracrine cascade led by nitric oxide and followed by serotonin (5-HT). In dogs with Pavlov pouches, found that supplementation of an amino acid-rich diet lacking Glu with monosodium Glu (MSG) enhanced the secretion of acid, pepsinogen, and fluid. However, MSG did not affect these secretions induced by a carbohydrate-rich diet and it had no effect on basal secretion when MSG was applied alone without the diet. Enhancement of gastric secretion by MSG was abolished by blockage of the gastric afferents using intra-gastric applied lidocaine. This effect of MSG was due in part to stimulation of 5-HT(3) receptors in the gastric mucosa.

Autophagy Inhibition Contributes to ROS-Producing NLRP3-Dependent Inflammasome Activation and Cytokine Secretion in High Glucose-Induced Macrophages.

PubMed

Dai, Jiezhi; Zhang, Xiaotian; Li, Li; Chen, Hua; Chai, Yimin

2017-01-01

Type 2 diabetes is a persistent inflammatory response that impairs the healing process. We hypothesized that stimulation with high glucose following a pro-inflammatory signal would lead to autophagy inhibition, reactive oxygen species (ROS) production and eventually to the activation of the Nod-like receptor protein (NLRP) -3. Macrophages were isolated from human diabetic wound. We measured the expression of NLRP3, caspase1 and interleukin-1 beta (IL-1β) by western blot and real-time PCR, and the surface markers on cells by flow cytometry. THP-1-derived macrophages exposed to high glucose were applied to study the link between autophagy, ROS and NLRP3 activation. LC3-II, P62, NLRP3 inflammation and IL-1β expression were measured by western blot and real-time PCR. ROS production was measured with a Cellular Reactive Oxygen Species Detection Assay Kit. Macrophages isolated from diabetic wounds exhibited a pro-inflammatory phenotype, including sustained NLRP3 inflammasome activity associated with IL-1β secretion. Our data showed that high glucose inhibited autophagy, induced ROS production, and activated NLRP3 inflammasome and cytokine secretion in THP-1-derived macrophages. To study high glucose-induced NLRP3 inflammasome signalling, we performed studies using an autophagy inducer, a ROS inhibitor and a NLRP3 inhibitor and found that all reduced the NLRP3 inflammasome activation and cytokine secretion. Sustained NLRP3 inflammasome activity in wound-derived macrophages contributes to the hyper-inflammation in human diabetic wounds. Autophagy inhibition and ROS generation play an essential role in high glucose-induced NLRP3 inflammasome activation and cytokine secretion in macrophages. © 2017 The Author(s). Published by S. Karger AG, Basel.

Identification of Novel Listeria monocytogenes Secreted Virulence Factors following Mutational Activation of the Central Virulence Regulator, PrfA▿ †

PubMed Central

Port, Gary C.; Freitag, Nancy E.

2007-01-01

Upon bacterial entry into the cytosol of infected mammalian host cells, the central virulence regulator PrfA of Listeria monocytogenes becomes activated and induces the expression of numerous factors which contribute to bacterial pathogenesis. The mechanism or signal by which PrfA becomes activated during the course of infection has not yet been determined; however, several amino acid substitutions within PrfA (known as PrfA* mutations) that appear to lock the protein into a constitutively activated state have been identified. In this study, the PrfA activation statuses of several L. monocytogenes mutant strains were subjected to direct isogenic comparison and the mutant with the highest activity, the prfA(L140F) mutant, was identified. The prfA(L140F) strain was subsequently used as a tool to identify gene products secreted as a result of PrfA activation. By use of two-dimensional gel electrophoresis followed by liquid chromatography-electrospray ionization-tandem mass spectroscopy analyses, 15 proteins were identified as up-regulated in the prfA(L140F) secretome, while the secretion of two proteins was found to be reduced. Although some of the proteins identified were known to be subject to direct regulation by PrfA, the majority have not previously been associated with PrfA regulation and their expression or secretion may be influenced indirectly by a PrfA-dependent regulatory pathway. Plasmid insertion inactivation of the genes encoding four novel secreted products indicated that three of the four have significant roles in L. monocytogenes virulence. The use of mutationally activated prfA alleles therefore provides a useful approach towards identifying gene products that contribute to L. monocytogenes pathogenesis. PMID:17938228

Oxytocin-secreting system: A major part of the neuroendocrine center regulating immunologic activity.

PubMed

Wang, Ping; Yang, Hai-Peng; Tian, Shujun; Wang, Liwei; Wang, Stephani C; Zhang, Fengmin; Wang, Yu-Feng

2015-12-15

Interactions between the nervous system and immune system have been studied extensively. However, the mechanisms underlying the neural regulation of immune activity, particularly the neuroendocrine regulation of immunologic functions, remain elusive. In this review, we provide a comprehensive examination of current evidence on interactions between the immune system and hypothalamic oxytocin-secreting system. We highlight the fact that oxytocin may have significant effects in the body, beyond its classical functions in lactation and parturition. Similar to the hypothalamo-pituitary-adrenal axis, the oxytocin-secreting system closely interacts with classical immune system, integrating both neurochemical and immunologic signals in the central nervous system and in turn affects immunologic defense, homeostasis, and surveillance. Lastly, this review explores therapeutic potentials of oxytocin in treating immunologic disorders. Copyright © 2015 Elsevier B.V. All rights reserved.

Expanded plug method for developing circumferential mechanical properties of tubular materials

DOEpatents

Hendrich, William Ray; McAfee, Wallace Jefferson; Luttrell, Claire Roberta

2006-11-28

A method for determining the circumferential properties of a tubular product, especially nuclear fuel cladding, utilizes compression of a polymeric plug within the tubular product to determine strain stress, yield stress and other properties. The process is especially useful in the determination of aging properties such as fuel rod embrittlement after long burn-down.

Plastic deformation of tubular crystals by dislocation glide.

PubMed

Beller, Daniel A; Nelson, David R

2016-09-01

Tubular crystals, two-dimensional lattices wrapped into cylindrical topologies, arise in many contexts, including botany and biofilaments, and in physical systems such as carbon nanotubes. The geometrical principles of botanical phyllotaxis, describing the spiral packings on cylinders commonly found in nature, have found application in all these systems. Several recent studies have examined defects in tubular crystals associated with crystalline packings that must accommodate a fixed tube radius. Here we study the mechanics of tubular crystals with variable tube radius, with dislocations interposed between regions of different phyllotactic packings. Unbinding and separation of dislocation pairs with equal and opposite Burgers vectors allow the growth of one phyllotactic domain at the expense of another. In particular, glide separation of dislocations offers a low-energy mode for plastic deformations of solid tubes in response to external stresses, reconfiguring the lattice step by step. Through theory and simulation, we examine how the tube's radius and helicity affects, and is in turn altered by, the mechanics of dislocation glide. We also discuss how a sufficiently strong bending rigidity can alter or arrest the deformations of tubes with small radii.

Band gap in tubular pillar phononic crystal plate.

PubMed

Shu, Fengfeng; Liu, Yongshun; Wu, Junfeng; Wu, Yihui

2016-09-01

In this paper, a phononic crystal (PC) plate with tubular pillars is presented and investigated. The band structures and mode displacement profiles are calculated by using finite element method. The result shows that a complete band gap opens when the ratio of the pillar height to the plate thickness is about 1.6. However, for classic cylinder pillar structures, a band gap opens when the ratio is equal or greater than 3. A tubular pillar design with a void room in it enhances acoustic multiple scattering and gives rise to the opening of the band gap. In order to verify it, a PC structure with double tubular pillars different in size (one within the other) is introduced and a more than 2times band gap enlargement is observed. Furthermore, the coupling between the resonant mode and the plate mode around the band gap is characterized, as well as the effect of the geometrical parameters on the band gap. The behavior of such structure could be utilized to design a pillar PC with stronger structural stability and to enlarge band gaps. Copyright © 2016 Elsevier B.V. All rights reserved.

Plastic deformation of tubular crystals by dislocation glide

NASA Astrophysics Data System (ADS)

Beller, Daniel A.; Nelson, David R.

2016-09-01

Tubular crystals, two-dimensional lattices wrapped into cylindrical topologies, arise in many contexts, including botany and biofilaments, and in physical systems such as carbon nanotubes. The geometrical principles of botanical phyllotaxis, describing the spiral packings on cylinders commonly found in nature, have found application in all these systems. Several recent studies have examined defects in tubular crystals associated with crystalline packings that must accommodate a fixed tube radius. Here we study the mechanics of tubular crystals with variable tube radius, with dislocations interposed between regions of different phyllotactic packings. Unbinding and separation of dislocation pairs with equal and opposite Burgers vectors allow the growth of one phyllotactic domain at the expense of another. In particular, glide separation of dislocations offers a low-energy mode for plastic deformations of solid tubes in response to external stresses, reconfiguring the lattice step by step. Through theory and simulation, we examine how the tube's radius and helicity affects, and is in turn altered by, the mechanics of dislocation glide. We also discuss how a sufficiently strong bending rigidity can alter or arrest the deformations of tubes with small radii.

Overexpressed cyclophilin B suppresses aldosterone-induced proximal tubular cell injury both in vitro and in vivo.

PubMed

Wang, Bin; Lin, Lilu; Wang, Haidong; Guo, Honglei; Gu, Yong; Ding, Wei

2016-10-25

The renin-angiotensin-aldosterone system (RAAS) is overactivated in patients with chronic kidney disease. Oxidative stress and endoplasmic reticulum stress (ERS) are two major mechanisms responsible for aldosterone-induced kidney injury. Cyclophilin (CYP) B is a chaperone protein that accelerates the rate of protein folding through its peptidyl-prolyl cis-trans isomerase (PPIase) activity. We report that overexpression of wild-type CYPB attenuated aldosterone-induced oxidative stress (evidenced by reduced production of reactive oxygen species and improved mitochondrial dysfunction), ERS (indicated by reduced expression of the ERS markers glucose-regulated protein 78 [GRP78] and C/-EBP homologous protein [CHOP]), and tubular cell apoptosis in comparison with aldosterone-induced human kidney-2 (HK-2) cells. The in vivo study also yielded similar results. Hence, CYPB performs a crucial function in protecting cells against aldosterone-induced oxidative stress, ERS, and tubular cell injury via its PPIase activity.

Overexpressed cyclophilin B suppresses aldosterone-induced proximal tubular cell injury both in vitro and in vivo

PubMed Central

Wang, Haidong; Guo, Honglei; Gu, Yong; Ding, Wei

2016-01-01

The renin-angiotensin-aldosterone system (RAAS) is overactivated in patients with chronic kidney disease. Oxidative stress and endoplasmic reticulum stress (ERS) are two major mechanisms responsible for aldosterone-induced kidney injury. Cyclophilin (CYP) B is a chaperone protein that accelerates the rate of protein folding through its peptidyl-prolyl cis-trans isomerase (PPIase) activity. We report that overexpression of wild-type CYPB attenuated aldosterone-induced oxidative stress (evidenced by reduced production of reactive oxygen species and improved mitochondrial dysfunction), ERS (indicated by reduced expression of the ERS markers glucose-regulated protein 78 [GRP78] and C/-EBP homologous protein [CHOP]), and tubular cell apoptosis in comparison with aldosterone-induced human kidney-2 (HK-2) cells. The in vivo study also yielded similar results. Hence, CYPB performs a crucial function in protecting cells against aldosterone-induced oxidative stress, ERS, and tubular cell injury via its PPIase activity. PMID:27732567

Anti-Diarrheal Mechanism of the Traditional Remedy Uzara via Reduction of Active Chloride Secretion

PubMed Central

Fromm, Anja; Günzel, Dorothee

2011-01-01

Background and Purpose The root extract of the African Uzara plant is used in traditional medicine as anti-diarrheal drug. It is known to act via inhibition of intestinal motility, but malabsorptive or antisecretory mechanisms are unknown yet. Experimental Approach HT-29/B6 cells and human colonic biopsies were studied in Ussing experiments in vitro. Uzara was tested on basal as well as on forskolin- or cholera toxin-induced Cl− secretion by measuring short-circuit current (ISC) and tracer fluxes of 22Na+ and 36Cl−. Para- and transcellular resistances were determined by two-path impedance spectroscopy. Enzymatic activity of the Na+/K+-ATPase and intracellular cAMP levels (ELISA) were measured. Key Results In HT-29/B6 cells, Uzara inhibited forskolin- as well as cholera toxin-induced ISC within 60 minutes indicating reduced active chloride secretion. Similar results were obtained in human colonic biopsies pre-stimulated with forskolin. In HT-29/B6, the effect of Uzara on the forskolin-induced ISC was time- and dose-dependent. Analyses of the cellular mechanisms of this Uzara effect revealed inhibition of the Na+/K+-ATPase, a decrease in forskolin-induced cAMP production and a decrease in paracellular resistance. Tracer flux experiments indicate that the dominant effect is the inhibition of the Na+/K+-ATPase. Conclusion and Implications Uzara exerts anti-diarrheal effects via inhibition of active chloride secretion. This inhibition is mainly due to an inhibition of the Na+/K+-ATPase and to a lesser extent to a decrease in intracellular cAMP responses and paracellular resistance. The results imply that Uzara is suitable for treating acute secretory diarrhea. PMID:21479205

Scaffold-Free Tubular Tissues Created by a Bio-3D Printer Undergo Remodeling and Endothelialization when Implanted in Rat Aortae

PubMed Central

Itoh, Manabu; Nakayama, Koichi; Noguchi, Ryo; Kamohara, Keiji; Furukawa, Kojirou; Uchihashi, Kazuyoshi; Toda, Shuji; Oyama, Jun-ichi; Node, Koichi; Morita, Shigeki

2015-01-01

Background Small caliber vascular prostheses are not clinically available because synthetic vascular prostheses lack endothelial cells which modulate platelet activation, leukocyte adhesion, thrombosis, and the regulation of vasomotor tone by the production of vasoactive substances. We developed a novel method to create scaffold-free tubular tissue from multicellular spheroids (MCS) using a “Bio-3D printer”-based system. This system enables the creation of pre-designed three-dimensional structures using a computer controlled robotics system. With this system, we created a tubular structure and studied its biological features. Methods and Results Using a “Bio-3D printer,” we made scaffold-free tubular tissues (inner diameter of 1.5 mm) from a total of 500 MCSs (2.5× 104 cells per one MCS) composed of human umbilical vein endothelial cells (40%), human aortic smooth muscle cells (10%), and normal human dermal fibroblasts (50%). The tubular tissues were cultured in a perfusion system and implanted into the abdominal aortas of F344 nude rats. We assessed the flow by ultrasonography and performed histological examinations on the second (n = 5) and fifth (n = 5) day after implantation. All grafts were patent and remodeling of the tubular tissues (enlargement of the lumen area and thinning of the wall) was observed. A layer of endothelial cells was confirmed five days after implantation. Conclusions The scaffold-free tubular tissues made of MCS using a Bio-3D printer underwent remodeling and endothelialization. Further studies are warranted to elucidate the underlying mechanism of endothelialization and its function, as well as the long-term results. PMID:26325298

ELKS active zone proteins as multitasking scaffolds for secretion

PubMed Central

Held, Richard G.

2018-01-01

Synaptic vesicle exocytosis relies on the tethering of release ready vesicles close to voltage-gated Ca2+ channels and specific lipids at the future site of fusion. This enables rapid and efficient neurotransmitter secretion during presynaptic depolarization by an action potential. Extensive research has revealed that this tethering is mediated by an active zone, a protein dense structure that is attached to the presynaptic plasma membrane and opposed to postsynaptic receptors. Although roles of individual active zone proteins in exocytosis are in part understood, the molecular mechanisms that hold the protein scaffold at the active zone together and link it to the presynaptic plasma membrane have remained unknown. This is largely due to redundancy within and across scaffolding protein families at the active zone. Recent studies, however, have uncovered that ELKS proteins, also called ERC, Rab6IP2 or CAST, act as active zone scaffolds redundant with RIMs. This redundancy has led to diverse synaptic phenotypes in studies of ELKS knockout mice, perhaps because different synapses rely to a variable extent on scaffolding redundancy. In this review, we first evaluate the need for presynaptic scaffolding, and we then discuss how the diverse synaptic and non-synaptic functional roles of ELKS support the hypothesis that ELKS provides molecular scaffolding for organizing vesicle traffic at the presynaptic active zone and in other cellular compartments. PMID:29491150

Hoopoes color their eggs with antimicrobial uropygial secretions

NASA Astrophysics Data System (ADS)

Soler, Juan J.; Martín-Vivaldi, M.; Peralta-Sánchez, J. M.; Arco, L.; Juárez-García-Pelayo, N.

2014-09-01

Uropygial gland secretions are used as cosmetics by some species of birds to color and enhance properties of feathers and teguments, which may signal individual quality. Uropygial secretions also reach eggshells during incubation and, therefore, may influence the coloration of birds' eggs, a trait that has attracted the attention of evolutionary biologists for more than one century. The color of hoopoe eggs typically changes along incubation, from bluish-gray to greenish-brown. Here, we test experimentally the hypothesis that dark uropygial secretion of females is responsible for such drastic color change. Moreover, since uropygial secretion of hoopoes has antimicrobial properties, we also explore the association between color and antimicrobial activity of the uropygial secretion of females. We found that eggs stayed bluish-gray in nests where female access to the uropygial secretion was experimentally blocked. Furthermore, experimental eggs that were maintained in incubators and manually smeared with uropygial secretion experienced similar color changes that naturally incubated eggs did, while control eggs that were not in contact with the secretions did not experience such color changes. All these results strongly support the hypothesis that female hoopoes use their uropygial gland secretion to color the eggs. Moreover, saturation of the uropygial secretion was associated with antimicrobial activity against Bacillus licheniformis. Given the known antimicrobial potential of uropygial secretions of birds, this finding opens the possibility that in scenarios of sexual selection, hoopoes in particular and birds in general signal antimicrobial properties of their uropygial secretion by mean of changes in egg coloration along incubation.

Two Novel Dermaseptin-Like Antimicrobial Peptides with Anticancer Activities from the Skin Secretion of Pachymedusa dacnicolor.

PubMed

Shi, Daning; Hou, Xiaojuan; Wang, Lei; Gao, Yitian; Wu, Di; Xi, Xinping; Zhou, Mei; Kwok, Hang Fai; Duan, Jinao; Chen, Tianbao; Shaw, Chris

2016-05-12

The dermaseptin antimicrobial peptide family contains members of 27-34 amino acids in length that have been predominantly isolated from the skins/skin secretions of phyllomedusine leaf frogs. By use of a degenerate primer in Rapid amplification of cDNA ends (RACE) PCR designed to a common conserved domain within the 5'-untranslated regions of previously-characterized dermaseptin encoding cDNAs, two novel members of this peptide family, named dermaseptin-PD-1 and dermaseptin-PD-2, were identified in the skin secretion of the phyllomedusine frog, Pachymedusa dacnicolor. The primary structures of both peptides were predicted from cloned cDNAs, as well as being confirmed by mass spectral analysis of crude skin secretion fractions resulted from reversed-phase high-performance liquid chromatography. Chemically-synthesized replicates of dermaseptin-PD-1 and dermaseptin-PD-2 were investigated for antimicrobial activity using standard model microorganisms (Gram-positive bacteria, Gram-negative bacteria and a yeast) and for cytotoxicity using mammalian red blood cells. The possibility of synergistic effects between the two peptides and their anti-cancer cell proliferation activities were assessed. The peptides exhibited moderate to high inhibition against the growth of the tested microorganisms and cancer cell lines with low haemolytic activity. Synergistic interaction between the two peptides in inhibiting the proliferation of Escherichia coli and human neuronal glioblastoma cell line, U251MG was also manifested.

Antileishmanial and antitrypanosomal activity of bufadienolides isolated from the toad Rhinella jimi parotoid macrogland secretion.

PubMed

Tempone, André Gustavo; Pimenta, Daniel Carvalho; Lebrun, Ivo; Sartorelli, Patrícia; Taniwaki, Noemi N; de Andrade, Heitor Franco; Antoniazzi, Marta Maria; Jared, Carlos

2008-07-01

Amphibian skin secretions are considered a rich source of biologically active compounds and are known to be rich in peptides, bufadienolides and alkaloids. Bufadienolides are cardioactive steroids from animals and plants that have also been reported to possess antimicrobial activities. Leishmaniasis and American Trypanosomiasis are parasitic diseases found in tropical and subtropical regions. The efforts toward the discovery of new treatments for these diseases have been largely neglected, despite the fact that the only available treatments are highly toxic drugs. In this work, we have isolated, through bioguided assays, the major antileishmanial compounds of the toad Rhinella jimi parotoid macrogland secretion. Mass spectrometry and (1)H and (13)C NMR spectroscopic analyses were able to demonstrate that the active molecules are telocinobufagin and hellebrigenin. Both steroids demonstrated activity against Leishmania (L.) chagasi promastigotes, but only hellebrigenin was active against Trypanosoma cruzi trypomastigotes. These steroids were active against the intracellular amastigotes of Leishmania, with no activation of nitric oxide production by macrophages. Neither cytotoxicity against mouse macrophages nor hemolytic activities were observed. The ultrastructural studies with promastigotes revealed the induction of mitochondrial damage and plasma membrane disturbances by telocinobufagin, resulting in cellular death. This novel biological effect of R. jimi steroids could be used as a template for the design of new therapeutics against Leishmaniasis and American Trypanosomiasis.

Self-Cleaning Tubular-Membrane Module

NASA Technical Reports Server (NTRS)

Sarbolouki, M. N.

1983-01-01

Tubular membranes made self-cleaning with aid of flow reversing valve. Sponge balls scrub membrane surfaces as they travel inside membrane tubes. A four-way flow-reversal valve automatically reverses flow in tubes at preset intervals so sponge balls reciprocate along tubes. Baskets at ends of tubes prevent sponges from escaping. Automatic cleaning feature added to existing membrane processing equipment with minimal modifications.

Effect of section shape on frequencies of natural oscillations of tubular springs

NASA Astrophysics Data System (ADS)

Pirogov, S. P.; Chuba, A. Yu; Cherentsov, D. A.

2018-05-01

The necessity of determining the frequencies of natural oscillations of manometric tubular springs is substantiated. Based on the mathematical model and computer program, numerical experiments were performed that allowed us to reveal the effect of geometric parameters on the frequencies of free oscillations of manometric tubular springs.

Optical analysis of solar energy tubular absorbers.

PubMed

Saltiel, C; Sokolov, M

1982-11-15

The energy absorbed by a solar energy tubular receiver element for a single incident ray is derived. Two types of receiver elements were analyzed: (1) an inner tube with an absorbing coating surrounded by a semitransparent cover tube, and (2) a semitransparent inner tube filled with an absorbing fluid surrounded by a semitransparent cover tube. The formation of ray cascades in the semitransparent tubes is considered. A numerical simulation to investigate the influence of the angle of incidence, sizing, thickness, and coefficient of extinction of the tubes was performed. A comparison was made between receiver elements with and without cover tubes. Ray tracing analyses in which rays were followed within the tubular receiver element as well as throughout the rest of the collector were performed for parabolic and circular trough concentrating collectors.

Bioinspired coupled helical coils for soft tissue engineering of tubular structures - Improved mechanical behavior of tubular collagen type I templates.

PubMed

Janke, H P; Bohlin, J; Lomme, R M L M; Mihaila, S M; Hilborn, J; Feitz, W F J; Oosterwijk, E

2017-09-01

The design of constructs for tubular tissue engineering is challenging. Most biomaterials need to be reinforced with supporting structures such as knittings, meshes or electrospun material to comply with the mechanical demands of native tissues. In this study, coupled helical coils (CHCs) were manufactured to mimic collagen fiber orientation as found in nature. Monofilaments of different commercially available biodegradable polymers were wound and subsequently fused, resulting in right-handed and left-handed polymer helices fused together in joints where the filaments cross. CHCs of different polymer composition were tested to determine the tensile strength, strain recovery, hysteresis, compressive strength and degradation of CHCs of different composition. Subsequently, seamless and stable hybrid constructs consisting of PDSII® USP 2-0 CHCs embedded in porous collagen type I were produced. Compared to collagen alone, this hybrid showed superior strain recovery (93.5±0.9% vs 71.1±12.6% in longitudinal direction; 87.1±6.6% vs 57.2±4.6% in circumferential direction) and hysteresis (18.9±2.7% vs 51.1±12.0% in longitudinal direction; 11.5±4.6% vs 46.3±6.3% in circumferential direction). Furthermore, this hybrid construct showed an improved Young's modulus in both longitudinal (0.5±0.1MPavs 0.2±0.1MPa; 2.5-fold) and circumferential (1.65±0.07MPavs (2.9±0.3)×10 -2 MPa; 57-fold) direction, respectively, compared to templates created from collagen alone. Moreover, hybrid template characteristics could be modified by changing the CHC composition and CHCs were produced showing a mechanical behavior similar to the native ureter. CHC-enforced templates, which are easily tunable to meet different demands may be promising for tubular tissue engineering. Most tubular constructs lack sufficient strength and tunability to comply with the mechanical demands of native tissues. Therefore, we embedded coupled helical coils (CHCs) produced from biodegradable polymers - to

HCO3(-) secretion by murine nasal submucosal gland serous acinar cells during Ca2+-stimulated fluid secretion.

PubMed

Lee, Robert J; Harlow, Janice M; Limberis, Maria P; Wilson, James M; Foskett, J Kevin

2008-07-01

Airway submucosal glands contribute to airway surface liquid (ASL) composition and volume, both important for lung mucociliary clearance. Serous acini generate most of the fluid secreted by glands, but the molecular mechanisms remain poorly characterized. We previously described cholinergic-regulated fluid secretion driven by Ca(2+)-activated Cl(-) secretion in primary murine serous acinar cells revealed by simultaneous differential interference contrast (DIC) and fluorescence microscopy. Here, we evaluated whether Ca(2+)-activated Cl(-) secretion was accompanied by secretion of HCO(3)(-), possibly a critical ASL component, by simultaneous measurements of intracellular pH (pH(i)) and cell volume. Resting pH(i) was 7.17 +/- 0.01 in physiological medium (5% CO(2)-25 mM HCO(3)(-)). During carbachol (CCh) stimulation, pH(i) fell transiently by 0.08 +/- 0.01 U concomitantly with a fall in Cl(-) content revealed by cell shrinkage, reflecting Cl(-) secretion. A subsequent alkalinization elevated pH(i) to above resting levels until agonist removal, whereupon it returned to prestimulation values. In nominally CO(2)-HCO(3)(-)-free media, the CCh-induced acidification was reduced, whereas the alkalinization remained intact. Elimination of driving forces for conductive HCO(3)(-) efflux by ion substitution or exposure to the Cl(-) channel inhibitor niflumic acid (100 microM) strongly inhibited agonist-induced acidification by >80% and >70%, respectively. The Na(+)/H(+) exchanger (NHE) inhibitor dimethylamiloride (DMA) increased the magnitude (greater than twofold) and duration of the CCh-induced acidification. Gene expression profiling suggested that serous cells express NHE isoforms 1-4 and 6-9, but pharmacological sensitivities demonstrated that alkalinization observed during both CCh stimulation and pH(i) recovery from agonist-induced acidification was primarily due to NHE1, localized to the basolateral membrane. These results suggest that serous acinar cells secrete HCO(3

Peptides and neurotransmitters that affect renin secretion

NASA Technical Reports Server (NTRS)

Ganong, W. F.; Porter, J. P.; Bahnson, T. D.; Said, S. I.

1984-01-01

Substance P inhibits renin secretion. This polypeptide is a transmitter in primary afferent neurons and is released from the peripheral as well as the central portions of these neurons. It is present in afferent nerves from the kidneys. Neuropeptide Y, which is a cotransmitter with norepinephrine and epinephrine, is found in sympathetic neurons that are closely associated with and presumably innervate the juxtagolmerular cells. Its effect on renin secretion is unknown, but it produces renal vasoconstriction and natriuresis. Vasoactive intestinal polypeptide (VIP) is a cotransmitter with acetylocholine in cholinergic neurons, and this polypeptide stimulates renin secretion. We cannot find any evidence for its occurence in neurons in the kidneys, but various stimuli increase plasma VIP to levels comparable to those produced by doses of exogenous VIP which stimulated renin secretion. Neostigmine increases plasma VIP and plasma renin activity, and the VIP appears to be responsible for the increase in renin secretion, since the increase is not blocked by renal denervation or propranolol. Stimulation of various areas in the brain produces sympathetically mediated increases in plasma renin activity associated with increases in blood pressure. However, there is pharmacological evidence that the renin response can be separated from the blood pressure response. In anaesthetized dogs, drugs that increase central serotonergic discharge increase renin secretion without increasing blood pressure. In rats, activation of sertonergic neurons in the dorsal raphe nucleus increases renin secretion by a pathway that projects from this nucleus to the ventral hypothalamus, and from there to the kidneys via the sympathetic nervous system. The serotonin releasing drug parachloramphetamine also increases plasma VIP, but VIP does not appear to be the primary mediator of the renin response. There is preliminary evidence that the serotonergic neurons in the dorsal raphe nucleus are part of the

THE FINE STRUCTURE OF SHEEP MYOCARDIAL CELLS; SARCOLEMMAL INVAGINATIONS AND THE TRANSVERSE TUBULAR SYSTEM

PubMed Central

Simpson, F. O.; Oertelis, S. J.

1962-01-01

An electron microscope study of sheep myocardial cells has demonstrated the presence of a transverse tubular system, apparently forming a network across the cell at each Z band level. The walls of these tubules resemble the sarcolemma in consisting of two dense layers—plasma membrane and basement menbrane; continuity of the tubule walls with the sarcolemma can be seen when longitudinal sections of a cell are obtained between two subsarcolemmal myofibrils and at the same time perpendicular to the cell surface. The demonstration of communication between the lumen of the transverse tubular system and the extracellular space appears to be more definite in this study than in any work hitherto published. It provides anatomical evidence of a possible direct pathway for transmission of the activating impulse from the sarcolemma to the myofibril Z bands. PMID:13913207

Production, secretion, and stability of human secreted alkaline phosphatase in tobacco NT1 cell suspension cultures.

PubMed

Becerra-Arteaga, Alejandro; Mason, Hugh S; Shuler, Michael L

2006-01-01

Tobacco NT1 cell suspension cultures secreting active human secreted alkaline phosphatase (SEAP) were generated for the first time as a model system to study recombinant protein production, secretion, and stability in plant cell cultures. The SEAP gene encodes a secreted form of the human placental alkaline phosphatase (PLAP). During batch culture, the highest level of active SEAP in the culture medium (0.4 U/mL, corresponding to approximately 27 mg/L) was observed at the end of the exponential growth phase. Although the level of active SEAP decreased during the stationary phase, the activity loss did not appear to be due to SEAP degradation (based on Western blots) but due to SEAP denaturation. The protein-stabilizing agents polyvinylpirrolidone (PVP) and bacitracin were added extracellularly to test for their ability to reduce the loss of SEAP activity during the stationary phase. Bacitracin (100 mg/L) was the most effective treatment at sustaining activity levels for up to 17 days post-subculture. Commercially available human placental alkaline phosphatase (PLAP) was used to probe the mechanism of SEAP deactivation. Experiments with PLAP in sterile and conditioned medium corroborated the denaturation of SEAP by factors generated by cell growth and not due to simple proteolysis. We also show for the first time that the factors promoting activity loss are heat labile at 95 degrees C but not at 70 degrees C, and they are not inactivated after a 5 day incubation period under normal culture conditions (27 degrees C). In addition, there were no significant changes in pH or redox potential when comparing sterile and cell-free conditioned medium during PLAP incubation, indicating that these factors were unimportant.

Pathophysiologic Changes in Extracellular pH Modulate Parathyroid Calcium-Sensing Receptor Activity and Secretion via a Histidine-Independent Mechanism.

PubMed

Campion, Katherine L; McCormick, Wanda D; Warwicker, Jim; Khayat, Mohd Ezuan Bin; Atkinson-Dell, Rebecca; Steward, Martin C; Delbridge, Leigh W; Mun, Hee-Chang; Conigrave, Arthur D; Ward, Donald T

2015-09-01

The calcium-sensing receptor (CaR) modulates renal calcium reabsorption and parathyroid hormone (PTH) secretion and is involved in the etiology of secondary hyperparathyroidism in CKD. Supraphysiologic changes in extracellular pH (pHo) modulate CaR responsiveness in HEK-293 (CaR-HEK) cells. Therefore, because acidosis and alkalosis are associated with altered PTH secretion in vivo, we examined whether pathophysiologic changes in pHo can significantly alter CaR responsiveness in both heterologous and endogenous expression systems and whether this affects PTH secretion. In both CaR-HEK and isolated bovine parathyroid cells, decreasing pHo from 7.4 to 7.2 rapidly inhibited CaR-induced intracellular calcium (Ca(2+)i) mobilization, whereas raising pHo to 7.6 potentiated responsiveness to extracellular calcium (Ca(2+)o). Similar pHo effects were observed for Ca(2+)o-induced extracellular signal-regulated kinase phosphorylation and actin polymerization and for L-Phe-induced Ca(2+)i mobilization. Intracellular pH was unaffected by acute 0.4-unit pHo changes, and the presence of physiologic albumin concentrations failed to attenuate the pHo-mediated effects. None of the individual point mutations created at histidine or cysteine residues in the extracellular domain of CaR attenuated pHo sensitivity. Finally, pathophysiologic pHo elevation reversibly suppressed PTH secretion from perifused human parathyroid cells, and acidosis transiently increased PTH secretion. Therefore, pathophysiologic pHo changes can modulate CaR responsiveness in HEK-293 and parathyroid cells independently of extracellular histidine residues. Specifically, pathophysiologic acidification inhibits CaR activity, thus permitting PTH secretion, whereas alkalinization potentiates CaR activity to suppress PTH secretion. These findings suggest that acid-base disturbances may affect the CaR-mediated control of parathyroid function and calcium metabolism in vivo. Copyright © 2015 by the American Society of

Lysophosphatidylinositol-induced activation of the cation channel TRPV2 triggers glucagon-like peptide-1 secretion in enteroendocrine L cells.

PubMed

Harada, Kazuki; Kitaguchi, Tetsuya; Kamiya, Taichi; Aung, Kyaw Htet; Nakamura, Kazuaki; Ohta, Kunihiro; Tsuboi, Takashi

2017-06-30

The lysophosphatidylinositol (LPI) has crucial roles in multiple physiological processes, including insulin exocytosis from pancreatic islets. However, the role of LPI in secretion of glucagon-like peptide-1 (GLP-1), a hormone that enhances glucose-induced insulin secretion, is unclear. Here, we used the murine enteroendocrine L cell line GLUTag and primary murine small intestinal cells to elucidate the mechanism of LPI-induced GLP-1 secretion. Exogenous LPI addition increased intracellular Ca 2+ concentrations ([Ca 2+ ] i ) in GLUTag cells and induced GLP-1 secretion from both GLUTag and acutely prepared primary intestinal cells. The [Ca 2+ ] i increase was suppressed by an antagonist for G protein-coupled receptor 55 (GPR55) and by silencing of GPR55 expression, indicating involvement of G q and G 12/13 signaling pathways in the LPI-induced increased [Ca 2+ ] i levels and GLP-1 secretion. However, GPR55 agonists did not mimic many of the effects of LPI. We also found that phospholipase C inhibitor and Rho-associated kinase inhibitor suppressed the [Ca 2+ ] i increase and that LPI increased the number of focal adhesions, indicating actin reorganization. Of note, blockage or silencing of transient receptor potential cation channel subfamily V member 2 (TRPV2) channels suppressed both the LPI-induced [Ca 2+ ] i increase and GLP-1 secretion. Furthermore, LPI accelerated TRPV2 translocation to the plasma membrane, which was significantly suppressed by a GPR55 antagonist. These findings suggest that TRPV2 activation via actin reorganization induced by G q and G 12/13 signaling is involved in LPI-stimulated GLP-1 secretion in enteroendocrine L cells. Because GPR55 agonists largely failed to mimic the effects of LPI, its actions on L cells are at least partially independent of GPR55 activation. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Hyperammonemia associated with distal renal tubular acidosis or urinary tract infection: a systematic review.

PubMed

Clericetti, Caterina M; Milani, Gregorio P; Lava, Sebastiano A G; Bianchetti, Mario G; Simonetti, Giacomo D; Giannini, Olivier

2018-03-01

Hyperammonemia usually results from an inborn error of metabolism or from an advanced liver disease. Individual case reports suggest that both distal renal tubular acidosis and urinary tract infection may also result in hyperammonemia. A systematic review of the literature on hyperammonemia secondary to distal renal tubular acidosis and urinary tract infection was conducted. We identified 39 reports on distal renal tubular acidosis or urinary tract infections in association with hyperammonemia published between 1980 and 2017. Hyperammonemia was detected in 13 children with distal renal tubular acidosis and in one adult patient with distal renal tubular acidosis secondary to primary hyperparathyroidism. In these patients a negative relationship was observed between circulating ammonia and bicarbonate levels (P < 0.05). In 31 patients (19 children, 12 adults), an acute urinary tract infection was complicated by acute hyperammonemia and symptoms and signs of acute neuronal dysfunction, such as an altered level of consciousness, convulsions and asterixis, often associated with signs of brain edema, such as anorexia and vomiting. Urea-splitting bacteria were isolated in 28 of the 31 cases. The urinary tract was anatomically or functionally abnormal in 30 of these patients. This study reveals that both altered distal renal tubular acidification and urinary tract infection may be associated with relevant hyperammonemia in both children and adults.

Tubular space truss structure for SKITTER 2 robot

NASA Technical Reports Server (NTRS)

Beecham, Richard; Dejulio, Linda; Delorme, Paul; Eck, Eric; Levy, Avi; Lowery, Joel; Radack, Joe; Sheffield, Randy; Stevens, Scott

1988-01-01

The Skitter 2 is a three legged transport vehicle designed to demonstrate the principle of a tripod walker in a multitude of environments. The tubular truss model of Skitter 2 is a proof of principal design. The model will replicate the operational capabilities of Skitter 2 including its ability to self-right itself. The project's focus was on the use of light weight tubular members in the final structural design. A strong design for the body was required as it will undergo the most intense loading. Triangular geometry was used extensively in the body, providing the required structural integrity and eliminating the need for cumbersome shear panels. Both the basic femur and tibia designs also relied on the strong geometry of the triangle. An intense literature search aided in the development of the most suitable weld techniques, joints, linkages, and materials required for a durable design. The hinge design features the use of spherical rod end bearings. In order to obtain a greater range of mobility in the tibia, a four-bar linkage was designed which attaches both to the femur and the tibia. All component designs, specifically the body, femur, and the tibia were optimized using the software package IDEAS 3.8A Supertab. The package provided essential deformation and stress analysis information on each component's design. The final structure incurred only a 0.0544 inch deflection in a maximum (worst case) loading situation. The highest stress experienced by any AL6061-T6 tubular member was 1920 psi. The structural integrity of the final design facilitated the use of Aluminum 6061-T6 tubing. The tubular truss structure of Skitter 2 is an effective and highly durable design. All facets of the design are structurally sound and cost effective.

Distinct Action of Flavonoids, Myricetin and Quercetin, on Epithelial Cl− Secretion: Useful Tools as Regulators of Cl− Secretion

PubMed Central

Sun, Hongxin; Niisato, Naomi; Nishio, Kyosuke; Hamilton, Kirk L.; Marunaka, Yoshinori

2014-01-01

Epithelial Cl− secretion plays important roles in water secretion preventing bacterial/viral infection and regulation of body fluid. We previously suggested that quercetin would be a useful compound for maintaining epithelial Cl− secretion at a moderate level irrespective of cAMP-induced stimulation. However, we need a compound that stimulates epithelial Cl− secretion even under cAMP-stimulated conditions, since in some cases epithelial Cl− secretion is not large enough even under cAMP-stimulated conditions. We demonstrated that quercetin and myricetin, flavonoids, stimulated epithelial Cl− secretion under basal conditions in epithelial A6 cells. We used forskolin, which activates adenylyl cyclase increasing cytosolic cAMP concentrations, to study the effects of quercetin and myricetin on cAMP-stimulated epithelial Cl− secretion. In the presence of forskolin, quercetin diminished epithelial Cl− secretion to a level similar to that with quercetin alone without forskolin. Conversely, myricetin further stimulated epithelial Cl− secretion even under forskolin-stimulated conditions. This suggests that the action of myricetin is via a cAMP-independent pathway. Therefore, myricetin may be a potentially useful compound to increase epithelial Cl− secretion under cAMP-stimulated conditions. In conclusion, myricetin would be a useful compound for prevention from bacterial/viral infection even under conditions that the amount of water secretion driven by cAMP-stimulated epithelial Cl− secretion is insufficient. PMID:24818160

Classification of capped tubular viral particles in the family of Papovaviridae

NASA Astrophysics Data System (ADS)

Keef, T.; Taormina, A.; Twarock, R.

2006-04-01

A vital constituent of a virus is its protein shell, called the viral capsid, that encapsulates and hence provides protection for the viral genome. Viral capsids are usually spherical, and for a significant number of viruses they exhibit overall icosahedral symmetry. The corresponding surface lattices, that encode the locations of the capsid proteins and intersubunit bonds, can be modelled by viral tiling theory. It has been shown in vitro that under a variation of the experimental boundary conditions, such as the pH value and salt concentration, tubular particles may appear instead of, or in addition to, spherical ones. In order to develop models that describe the simultaneous assembly of both spherical and tubular variants, and hence study the possibility of triggering tubular malformations as a means of interference with the replication mechanism, viral tiling theory has to be extended to include tubular lattices with end caps. We focus here on the case of Papovaviridae, which play a distinguished role from the viral structural point of view as they correspond to all pentamer lattices, i.e. lattices formed from clusters of five protein subunits throughout. These results pave the way for a generalization of recently developed assembly models.

Outer Membrane Vesicles Prime and Activate Macrophage Inflammasomes and Cytokine Secretion In Vitro and In Vivo

PubMed Central

Cecil, Jessica D.; O’Brien-Simpson, Neil M.; Lenzo, Jason C.; Holden, James A.; Singleton, William; Perez-Gonzalez, Alexis; Mansell, Ashley; Reynolds, Eric C.

2017-01-01

Outer membrane vesicles (OMVs) are proteoliposomes blebbed from the surface of Gram-negative bacteria. Chronic periodontitis is associated with an increase in subgingival plaque of Gram-negative bacteria, Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia. In this study, we investigated the immune-modulatory effects of P. gingivalis, T. denticola, and T. forsythia OMVs on monocytes and differentiated macrophages. All of the bacterial OMVs were phagocytosed by monocytes, M(naïve) and M(IFNγ) macrophages in a dose-dependent manner. They also induced NF-κB activation and increased TNFα, IL-8, and IL-1β cytokine secretion. P. gingivalis OMVs were also found to induce anti-inflammatory IL-10 secretion. Although unprimed monocytes and macrophages were resistant to OMV-induced cell death, lipopolysaccharide or OMV priming resulted in a significantly reduced cell viability. P. gingivalis, T. denticola, and T. forsythia OMVs all activated inflammasome complexes, as monitored by IL-1β secretion and ASC speck formation. ASC was critical for OMV-induced inflammasome formation, while AIM2−/− and Caspase-1−/− cells had significantly reduced inflammasome formation and NLRP3−/− cells exhibited a slight reduction. OMVs were also found to provide both priming and activation of the inflammasome complex. High-resolution microscopy and flow cytometry showed that P. gingivalis OMVs primed and activated macrophage inflammasomes in vivo with 80% of macrophages exhibiting inflammasome complex formation. In conclusion, periodontal pathogen OMVs were found to have significant immunomodulatory effects upon monocytes and macrophages and should therefore influence pro-inflammatory host responses associated with disease. PMID:28890719

Characterization of lipoprotein lipase activity, secretion, and degradation at different sites of post-translational processing in primary cultures of rat adipocytes.

PubMed

Simsolo, R B; Ong, J M; Kern, P A

1992-12-01

The regulation of adipose tissue lipoprotein lipase (LPL) by feeding and fasting occurs through post-translational changes in the LPL protein. In addition, LPL activity and secretion are decreased when N-linked glycosylation is inhibited. To better understand the role of oligosaccharide processing in the development of LPL activity and in LPL secretion, primary cultures of rat adipocytes were treated with inhibitors of oligosaccharide processing. LPL catalytic activity from the heparin-releasable fraction of adipocytes was inhibited by more than 70%, with similar decreases in LPL mass, when cells were cultured for 24 h in the presence of either tunicamycin or castanospermine. On the other hand, deoxymannojirimycin (DMJ) and swainsonine had no effect on LPL activity. LPL secretion was examined after pulse-labeling cells with [35S]methionine. The appearance of 35S-labeled LPL in the medium was blocked by treatment of cells with tunicamycin and castanospermine, whereas secretion was not affected by DMJ or swainsonine. To examine the effect of oligosaccharide processing on LPL intracellular degradation, adipocytes were treated with tunicamycin, castanospermine, and DMJ and then pulse-labeled with [35S]methionine, followed by a chase with unlabeled methionine for 120 min. The unglycosylated [35S]LPL that was synthesized in the presence of tunicamycin demonstrated essentially no intracellular degradation. In the presence of castanospermine and DMJ, the half-life of newly synthesized LPL was increased to 81 and 113 min, as compared to 65 min in control cells. Thus, castanospermine-treated adipocytes demonstrated a decrease in LPL activity and secretion, suggesting that the glucosidase-mediated cleavage of terminal glucose residues from oligosaccharides is a critical step in LPL maturation.(ABSTRACT TRUNCATED AT 250 WORDS)

Buckling characteristics of hypersonic aircraft wing tubular panels

NASA Technical Reports Server (NTRS)

Ko, William L.; Shideler, John L.; Fields, Roger A.

1986-01-01

The buckling characteristics of Rene 41 tubular panels installed as wing panels on a hypersonic wing test structure (HWTS) were determined nondestructively through use of a force/stiffness technique. The nondestructive buckling tests were carried out under different combined load conditions and different temperature environments. Two panels were subsequently tested to buckling failure in a universal tension compression testing machine. In spite of some data scattering because of large extrapolations of data points resulting from termination of the test at a somewhat low applied load, the overall test data correlated fairly well with theoretically predicted buckling interaction curves. The structural efficiency of the tubular panels was slightly higher than that of the beaded panels which they replaced.

Congenital myasthenic syndrome with tubular aggregates caused by GFPT1 mutations.

PubMed

Guergueltcheva, Velina; Müller, Juliane S; Dusl, Marina; Senderek, Jan; Oldfors, Anders; Lindbergh, Christopher; Maxwell, Susan; Colomer, Jaume; Mallebrera, Cecilia Jimenez; Nascimento, Andres; Vilchez, Juan J; Muelas, Nuria; Kirschner, Janbernd; Nafissi, Shahriar; Kariminejad, Ariana; Nilipour, Yalda; Bozorgmehr, Bita; Najmabadi, Hossein; Rodolico, Carmelo; Sieb, Jörn P; Schlotter, Beate; Schoser, Benedikt; Herrmann, Ralf; Voit, Thomas; Steinlein, Ortrud K; Najafi, Abdolhamid; Urtizberea, Andoni; Soler, Doriette M; Muntoni, Francesco; Hanna, Michael G; Chaouch, Amina; Straub, Volker; Bushby, Kate; Palace, Jacqueline; Beeson, David; Abicht, Angela; Lochmüller, Hanns

2012-05-01

Congenital myasthenic syndrome (CMS) is a clinically and genetically heterogeneous group of inherited disorders of the neuromuscular junction. A difficult to diagnose subgroup of CMS is characterised by proximal muscle weakness and fatigue while ocular and facial involvement is only minimal. DOK7 mutations have been identified as causing the disorder in about half of the cases. More recently, using classical positional cloning, we have identified mutations in a previously unrecognised CMS gene, GFPT1, in a series of DOK7-negative cases. However, detailed description of clinical features of GFPT1 patients has not been reported yet. Here we describe the clinical picture of 24 limb-girdle CMS (LG-CMS) patients and pathological findings of 18 of them, all carrying GFPT1 mutations. Additional patients with CMS, but without tubular aggregates, and patients with non-fatigable weakness with tubular aggregates were also screened. In most patients with GFPT1 mutations, onset of the disease occurs in the first decade of life with characteristic limb-girdle weakness and fatigue. A common feature was beneficial and sustained response to acetylcholinesterase inhibitor treatment. Most of the patients who had a muscle biopsy showed tubular aggregates in myofibers. Analysis of endplate morphology in one of the patients revealed unspecific abnormalities. Our study delineates the phenotype of CMS associated with GFPT1 mutations and expands the understanding of neuromuscular junction disorders. As tubular aggregates in context of a neuromuscular transmission defect appear to be highly indicative, we suggest calling this condition congenital myasthenic syndrome with tubular aggregates (CMS-TA).

Tissue cell assisted fabrication of tubular catalytic platinum microengines

NASA Astrophysics Data System (ADS)

Wang, Hong; Moo, James Guo Sheng; Pumera, Martin

2014-09-01

We report a facile platform for mass production of robust self-propelled tubular microengines. Tissue cells extracted from fruits of banana and apple, Musa acuminata and Malus domestica, are used as the support on which a thin platinum film is deposited by means of physical vapor deposition. Upon sonication of the cells/Pt-coated substrate in water, microscrolls of highly uniform sizes are spontaneously formed. Tubular microengines fabricated with the fruit cell assisted method exhibit a fast motion of ~100 bodylengths per s (~1 mm s-1). An extremely simple and affordable platform for mass production of the micromotors is crucial for the envisioned swarms of thousands and millions of autonomous micromotors performing biomedical and environmental remediation tasks.We report a facile platform for mass production of robust self-propelled tubular microengines. Tissue cells extracted from fruits of banana and apple, Musa acuminata and Malus domestica, are used as the support on which a thin platinum film is deposited by means of physical vapor deposition. Upon sonication of the cells/Pt-coated substrate in water, microscrolls of highly uniform sizes are spontaneously formed. Tubular microengines fabricated with the fruit cell assisted method exhibit a fast motion of ~100 bodylengths per s (~1 mm s-1). An extremely simple and affordable platform for mass production of the micromotors is crucial for the envisioned swarms of thousands and millions of autonomous micromotors performing biomedical and environmental remediation tasks. Electronic supplementary information (ESI) available: Related video. See DOI: 10.1039/c4nr03720k

Leptin enhances the secretion of interleukin (IL)-18, but not IL-1β, from human monocytes via activation of caspase-1.

PubMed

Jitprasertwong, Paiboon; Jaedicke, Katrin M; Nile, Christopher J; Preshaw, Philip M; Taylor, John J

2014-02-01

Circulating levels of leptin are elevated in type-2 diabetes mellitus (T2DM) and leptin plays a role in immune responses. Elevated circulating IL-18 levels are associated with clinical complications of T2DM. IL-18 regulates cytokine secretion and the function of a number of immune cells including T-cells, neutrophils and macrophages and as such has a key role in immunity and inflammation. Pro-inflammatory monocytes exhibiting elevated cytokine secretion are closely associated with inflammation in T2DM, however, little is known about the role of leptin in modifying monocyte IL-18 secretion. We therefore aimed to investigate the effect of leptin on IL-18 secretion by monocytes. We report herein that leptin increases IL-18 secretion in THP-1 and primary human monocytes but has no effect on IL-18mRNA. Leptin and LPS signalling in monocytes occurs by overlapping but distinct pathways. Thus, in contrast to a strong stimulation by LPS, leptin has no effect on IL-1βmRNA levels or IL-1β secretion. In addition, LPS stimulates the secretion of IL-6 but leptin did not whereas both treatments up regulate IL-8 secretion from the same cells. Although leptin (and LPS) has a synergistic effect with exogenous ATP on IL-18 secretion in both THP-1 and primary monocytes, experiments involving ATP assays and pharmacological inhibition of ATP signalling failed to provide any evidence that endogenous ATP secreted by leptin-stimulated monocytes was responsible for enhancement of monocyte IL-18 secretion by leptin. Analysis of the action of caspase-1 revealed that leptin up regulates caspase-1 activity and the effect of leptin on IL-18 release is prevented by caspase-1 inhibitor (Ac-YVAD-cmk). These data suggest that leptin activates IL-18 processing rather than IL-18 transcription. In conclusion, leptin enhances IL-18 secretion via modulation of the caspase-1 inflammasome function and acts synergistically with ATP in this regard. This process may contribute to aberrant immune responses

Albumin stimulates renal tubular inflammation through an HSP70-TLR4 axis in mice with early diabetic nephropathy

PubMed Central

Jheng, Huei-Fen; Tsai, Pei-Jane; Chuang, Yi-Lun; Shen, Yi-Ting; Tai, Ting-An; Chen, Wen-Chung; Chou, Chuan-Kai; Ho, Li-Chun; Tang, Ming-Jer; Lai, Kuei-Tai A.; Sung, Junne-Ming; Tsai, Yau-Sheng

2015-01-01

ABSTRACT Increased urinary albumin excretion is not simply an aftermath of glomerular injury, but is also involved in the progression of diabetic nephropathy (DN). Whereas Toll-like receptors (TLRs) are incriminated in the renal inflammation of DN, whether and how albumin is involved in the TLR-related renal inflammatory response remains to be clarified. Here, we showed that both TLR2 and TLR4, one of their putative endogenous ligands [heat shock protein 70 (HSP70)] and nuclear factor-κB promoter activity were markedly elevated in the kidneys of diabetic mice. A deficiency of TLR4 but not of TLR2 alleviated albuminuria, tubulointerstitial fibrosis and inflammation induced by diabetes. The protection against renal injury in diabetic Tlr4−/− mice was associated with reduced tubular injuries and preserved cubilin levels, rather than amelioration of glomerular lesions. In vitro studies revealed that albumin, a stronger inducer than high glucose (HG), induced the release of HSP70 from proximal tubular cells. HSP70 blockade ameliorated albumin-induced inflammatory mediators. HSP70 triggered the production of inflammatory mediators in a TLR4-dependent manner. Moreover, HSP70 inhibition in vivo ameliorated diabetes-induced albuminuria, inflammatory response and tubular injury. Finally, we found that individuals with DN had higher levels of TLR4 and HSP70 in the dilated tubules than non-diabetic controls. Thus, activation of the HSP70-TLR4 axis, stimulated at least in part by albumin, in the tubular cell is a newly identified mechanism associated with induction of tubulointerstitial inflammation and aggravation of pre-existing microalbuminuria in the progression of DN. PMID:26398934

Disruption of gap junctions attenuates aminoglycoside-elicited renal tubular cell injury.

PubMed

Yao, Jian; Huang, Tao; Fang, Xin; Chi, Yuan; Zhu, Ying; Wan, Yigang; Matsue, Hiroyuki; Kitamura, Masanori

2010-08-01

Gap junctions play important roles in the regulation of cell phenotype and in determining cell survival after various insults. Here, we investigated the role of gap junctions in aminoglycoside-induced injury to renal tubular cells. Two tubular epithelial cell lines NRK-E52 and LLC-PK1 were compared for gap junction protein expression and function by immunofluorescent staining, Western blot and dye transfer assay. Cell viability after exposure to aminoglycosides was evaluated by WST assay. Gap junctions were modulated by transfection of the gap junction protein, connexin 43 (Cx43), use of Cx43 siRNA and gap junction inhibitors. NRK-E52 cells expressed abundant Cx43 and were functionally coupled by gap junctional intercellular communication (GJIC). Exposure of NRK-E52 cells to aminoglycosides, G418 and hygromycin, increased Cx43 phosphorylation and GJIC. The aminoglycosides also decreased cell viability that was prevented by gap junction inhibitors and Cx43 siRNA. LLC-PK1 cells were gap junction-deficient and resistant to aminoglycoside-induced cytotoxicity. Over-expression of a wild-type Cx43 converted LLC-PK1 cells to a drug-sensitive phenotype. The gap junction inhibitor alpha-glycyrrhetinic acid (alpha-GA) activated Akt in NRK-E52 cells. Inhibition of the Akt pathway enhanced cell toxicity to G418 and abolished the protective effects of alpha-GA. In addition, gentamycin-elicited cytotoxicity in NRK-E52 cells was also significantly attenuated by alpha-GA. Gap junctions contributed to the cytotoxic effects of aminoglycosides. Modulation of gap junctions could be a promising approach for prevention and treatment of aminoglycoside-induced renal tubular cell injury.

Regulation of Cl(-) secretion by AMPK in vivo.

PubMed

Kongsuphol, Patthara; Hieke, Bernhard; Ousingsawat, Jiraporn; Almaca, Joana; Viollet, Benoit; Schreiber, Rainer; Kunzelmann, Karl

2009-03-01

Previous in vitro studies suggested that Cl(-) currents produced by the cystic fibrosis transmembrane conductance regulator (CFTR; ABCC7) are inhibited by the alpha1 isoform of the adenosine monophosphate (AMP)-stimulated kinase (AMPK). AMPK is a serine/threonine kinase that is activated during metabolic stress. It has been proposed as a potential mediator for transport-metabolism coupling in epithelial tissues. All previous studies have been performed in vitro and thus little is known about the regulation of Cl(-) secretion by AMPK in vivo. Using AMPKalpha1(-/-) mice and wild-type littermates, we demonstrate that phenformin, an activator of AMPK, strongly inhibits cAMP-activated Cl(-) secretion in mouse airways and colon, when examined in ex vivo in Ussing chamber recordings. However, phenformin was equally effective in AMPKalpha1(-/-) and wild-type animals, suggesting additional AMPK-independent action of phenformin. Phenformin inhibited CFTR Cl(-) conductance in basolaterally permeabilized colonic epithelium from AMPKalpha1(+/+) but not AMPKalpha1(-/-) mice. The inhibitor of AMPK compound C enhanced CFTR-mediated Cl(-) secretion in epithelial tissues of AMPKalpha1(-/-) mice, but not in wild-type littermates. There was no effect on Ca(2+)-mediated Cl(-) secretion, activated by adenosine triphosphate or carbachol. Moreover CFTR-dependent Cl(-) secretion was enhanced in the colon of AMPKalpha1(-/-) mice, as indicated in Ussing chamber ex vivo and rectal PD measurements in vivo. Taken together, these data suggest that epithelial Cl(-) secretion mediated by CFTR is controlled by AMPK in vivo.

Tubular Heart Pumping Mechanisms in Ciona Intestinalis

NASA Astrophysics Data System (ADS)

Battista, Nicholas; Miller, Laura

2015-11-01

In vertebrate embryogenesis, the first organ to form is the heart, beginning as a primitive heart tube. However, many invertebrates have tubular hearts from infancy through adulthood. Heart tubes have been described as peristaltic and impedance pumps. Impedance pumping assumes a single actuation point of contraction, while traditional peristalsis assumes a traveling wave of actuation. In addition to differences in flow, this inherently implies differences in the conduction system. It is possible to transition from pumping mechanism to the other with a change in the diffusivity of the action potential. In this work we consider the coupling between the fluid dynamics and electrophysiology of both mechanisms, within a basal chordate, the tunicate. Using CFD with a neuro-mechanical model of tubular pumping, we discuss implications of the both mechanisms. Furthermore, we discuss the implications of the pumping mechanism on evolution and development.

Enhanced secretion of natto phytase by Bacillus subtilis.

PubMed

Tsuji, Shogo; Tanaka, Kosei; Takenaka, Shinji; Yoshida, Ken-ichi

2015-01-01

Phytases comprise a group of phosphatases that trim inorganic phosphates from phytic acid (IP6). In this study, we aimed to achieve the efficient secretion of phytase by Bacillus subtilis. B. subtilis laboratory standard strain 168 and its derivatives exhibit no phytase activity, whereas a natto starter secretes phytase actively. The natto phytase gene was cloned into strain RIK1285, a protease-defective derivative of 168, to construct a random library of its N-terminal fusions with 173 different signal peptides (SPs) identified in the 168 genome. The library was screened to assess the efficiency of phytase secretion based on clear zones around colonies on plates, which appeared when IP6 was hydrolyzed. The pbp SP enhanced the secretion of the natto phytase most efficiently, i.e. twice that of the original SP. Thus, the secreted natto phytase was purified and found to remove up to 3 phosphates from IP6.

Renal Tubular Acidosis in Patients with Primary Sjögren's Syndrome.

PubMed

Jung, Su Woong; Park, Eun Ji; Kim, Jin Sug; Lee, Tae Won; Ihm, Chun Gyoo; Lee, Sang Ho; Moon, Ju-Young; Kim, Yang Gyun; Jeong, Kyung Hwan

2017-09-01

Primary Sjögren's syndrome (pSS) is characterized by lymphocytic infiltration of the exocrine glands resulting in decreased saliva and tear production. It uncommonly involves the kidneys in various forms, including tubulointerstitial nephritis, renal tubular acidosis, Fanconi syndrome, and rarely glomerulonephritis. Its clinical symptoms include muscle weakness, periodic paralysis, and bone pain due to metabolic acidosis and electrolyte imbalance. Herein, we describe the cases of two women with pSS whose presenting symptoms involve the kidneys. They had hypokalemia and normal anion gap metabolic acidosis due to distal renal tubular acidosis and positive anti-SS-A and anti-SS-B autoantibodies. Since one of them experienced femoral fracture due to osteomalacia secondary to renal tubular acidosis, an earlier diagnosis of pSS is important in preventing serious complications.

The Tuberin/mTOR Pathway Promotes Apoptosis of Tubular Epithelial Cells in Diabetes

PubMed Central

Velagapudi, Chakradhar; Bhandari, Basant S.; Abboud-Werner, Sherry; Simone, Simona; Abboud, Hanna E.

2011-01-01

Apoptosis contributes to the development of diabetic nephropathy, but the mechanism by which high glucose (HG) induces apoptosis is not fully understood. Because the tuberin/mTOR pathway can modulate apoptosis, we studied the role of this pathway in apoptosis in type I diabetes and in cultured proximal tubular epithelial (PTE) cells exposed to HG. Compared with control rats, diabetic rats had more apoptotic cells in the kidney cortex. Induction of diabetes also increased phosphorylation of tuberin in association with mTOR activation (measured by p70S6K phosphorylation), inactivation of Bcl-2, increased cytosolic cytochrome c expression, activation of caspase 3, and cleavage of PARP; insulin treatment prevented these changes. In vitro, exposure of PTE cells to HG increased phosphorylation of tuberin and p70S6K, phosphorylation of Bcl-2, expression of cytosolic cytochrome c, and caspase 3 activity. High glucose induced translocation of the caspase substrate YY1 from the cytoplasm to the nucleus and enhanced cleavage of PARP. Pretreatment the cells with the mTOR inhibitor rapamycin reduced the number of apoptotic cells induced by HG and the downstream effects of mTOR activation noted above. Furthermore, gene silencing of tuberin with siRNA decreased cleavage of PARP. These data show that the tuberin/mTOR pathway promotes apoptosis of tubular epithelial cells in diabetes, mediated in part by cleavage of PARP by YY1. PMID:21289215

The probability of quantal secretion near a single calcium channel of an active zone.

PubMed Central

Bennett, M R; Farnell, L; Gibson, W G

2000-01-01

A Monte Carlo analysis has been made of calcium dynamics and quantal secretion at microdomains in which the calcium reaches very high concentrations over distances of <50 nm from a channel and for which calcium dynamics are dominated by diffusion. The kinetics of calcium ions in microdomains due to either the spontaneous or evoked opening of a calcium channel, both of which are stochastic events, are described in the presence of endogenous fixed and mobile buffers. Fluctuations in the number of calcium ions within 50 nm of a channel are considerable, with the standard deviation about half the mean. Within 10 nm of a channel these numbers of ions can give rise to calcium concentrations of the order of 100 microM. The temporal changes in free calcium and calcium bound to different affinity indicators in the volume of an entire varicosity or bouton following the opening of a single channel are also determined. A Monte Carlo analysis is also presented of how the dynamics of calcium ions at active zones, after the arrival of an action potential and the stochastic opening of a calcium channel, determine the probability of exocytosis from docked vesicles near the channel. The synaptic vesicles in active zones are found docked in a complex with their calcium-sensor associated proteins and a voltage-sensitive calcium channel, forming a secretory unit. The probability of quantal secretion from an isolated secretory unit has been determined for different distances of an open calcium channel from the calcium sensor within an individual unit: a threefold decrease in the probability of secretion of a quantum occurs with a doubling of the distance from 25 to 50 nm. The Monte Carlo analysis also shows that the probability of secretion of a quantum is most sensitive to the size of the single-channel current compared with its sensitivity to either the binding rates of the sites on the calcium-sensor protein or to the number of these sites that must bind a calcium ion to trigger

Interleukin-33-Activated Islet-Resident Innate Lymphoid Cells Promote Insulin Secretion through Myeloid Cell Retinoic Acid Production.

PubMed

Dalmas, Elise; Lehmann, Frank M; Dror, Erez; Wueest, Stephan; Thienel, Constanze; Borsigova, Marcela; Stawiski, Marc; Traunecker, Emmanuel; Lucchini, Fabrizio C; Dapito, Dianne H; Kallert, Sandra M; Guigas, Bruno; Pattou, Francois; Kerr-Conte, Julie; Maechler, Pierre; Girard, Jean-Philippe; Konrad, Daniel; Wolfrum, Christian; Böni-Schnetzler, Marianne; Finke, Daniela; Donath, Marc Y

2017-11-21

Pancreatic-islet inflammation contributes to the failure of β cell insulin secretion during obesity and type 2 diabetes. However, little is known about the nature and function of resident immune cells in this context or in homeostasis. Here we show that interleukin (IL)-33 was produced by islet mesenchymal cells and enhanced by a diabetes milieu (glucose, IL-1β, and palmitate). IL-33 promoted β cell function through islet-resident group 2 innate lymphoid cells (ILC2s) that elicited retinoic acid (RA)-producing capacities in macrophages and dendritic cells via the secretion of IL-13 and colony-stimulating factor 2. In turn, local RA signaled to the β cells to increase insulin secretion. This IL-33-ILC2 axis was activated after acute β cell stress but was defective during chronic obesity. Accordingly, IL-33 injections rescued islet function in obese mice. Our findings provide evidence that an immunometabolic crosstalk between islet-derived IL-33, ILC2s, and myeloid cells fosters insulin secretion. Copyright © 2017 Elsevier Inc. All rights reserved.

HCO3− Secretion by Murine Nasal Submucosal Gland Serous Acinar Cells during Ca2+-stimulated Fluid Secretion

PubMed Central

Lee, Robert J.; Harlow, Janice M.; Limberis, Maria P.; Wilson, James M.; Foskett, J. Kevin

2008-01-01

Airway submucosal glands contribute to airway surface liquid (ASL) composition and volume, both important for lung mucociliary clearance. Serous acini generate most of the fluid secreted by glands, but the molecular mechanisms remain poorly characterized. We previously described cholinergic-regulated fluid secretion driven by Ca2+-activated Cl− secretion in primary murine serous acinar cells revealed by simultaneous differential interference contrast (DIC) and fluorescence microscopy. Here, we evaluated whether Ca2+-activated Cl− secretion was accompanied by secretion of HCO3−, possibly a critical ASL component, by simultaneous measurements of intracellular pH (pHi) and cell volume. Resting pHi was 7.17 ± 0.01 in physiological medium (5% CO2–25 mM HCO3−). During carbachol (CCh) stimulation, pHi fell transiently by 0.08 ± 0.01 U concomitantly with a fall in Cl− content revealed by cell shrinkage, reflecting Cl− secretion. A subsequent alkalinization elevated pHi to above resting levels until agonist removal, whereupon it returned to prestimulation values. In nominally CO2–HCO3−-free media, the CCh-induced acidification was reduced, whereas the alkalinization remained intact. Elimination of driving forces for conductive HCO3− efflux by ion substitution or exposure to the Cl− channel inhibitor niflumic acid (100 μM) strongly inhibited agonist-induced acidification by >80% and >70%, respectively. The Na+/H+ exchanger (NHE) inhibitor dimethylamiloride (DMA) increased the magnitude (greater than twofold) and duration of the CCh-induced acidification. Gene expression profiling suggested that serous cells express NHE isoforms 1–4 and 6–9, but pharmacological sensitivities demonstrated that alkalinization observed during both CCh stimulation and pHi recovery from agonist-induced acidification was primarily due to NHE1, localized to the basolateral membrane. These results suggest that serous acinar cells secrete HCO3− during Ca2+-evoked fluid

Effect of activators and inhibitors of K+ channels on insulin secretion in the amphibian pancreas.

PubMed

Francini, F; Pirotte, B; Gagliardino, J J

1997-02-01

The aim of this study was to obtain pharmacological evidence for the presence and participation of K+ channels in amphibian pancreatic islets. Pancreases from the toad Bufo arenarum were thus incubated with activators or blockers of K+ channels and the immunoreactive insulin released into the medium was measured by radioimmunoassay. Two K(+)-ATP channel openers (diazoxide and BPDZ44) inhibited; while a K(+)-ATP channel blocker (tolbutamide) and metabolizable sugars (glucose, glyceraldehyde) significantly stimulated the output of insulin. Although a nonmetabolizable sugar (galactose) failed to increase insulin release, dinitrophenol decreased the secretagogue effect of glucose. By contrast, although somatostatin and clonidine blocked the release of insulin, tetraethylammonium significantly stimulated secretion. For each compound tested, the effects on both insulin secretion and B-cell K+ channel activity were similar to those observed in the mammalian pancreas. These findings point to the existence of mammalian-like K+ channels in the B-cells of some amphibians.

Effect of corrosion on the buckling capacity of tubular members

NASA Astrophysics Data System (ADS)

Øyasæter, F. H.; Aeran, A.; Siriwardane, S. C.; Mikkelsen, O.

2017-12-01

Offshore installations are subjected to harsh marine environment and often have damages from corrosion. Several experimental and numerical studies were performed in the past to estimate buckling capacity of corroded tubular members. However, these studies were either based on limited experimental tests or numerical analyses of few cases resulting in semi-empirical relations. Also, there are no guidelines and recommendations in the currently available design standards. To fulfil this research gap, a new formula is proposed to estimate the residual strength of tubular members considering corrosion and initial geometrical imperfections. The proposed formula is verified with results from finite element analyses performed on several members and for varying corrosion patch parameters. The members are selected to represent the most relevant Eurocode buckling curve for tubular members. It is concluded that corrosion reduces the buckling capacity significantly and the proposed formula can be easily applied by practicing engineers without performing detailed numerical analyses.

Augmented reality visualization of deformable tubular structures for surgical simulation.

PubMed

Ferrari, Vincenzo; Viglialoro, Rosanna Maria; Nicoli, Paola; Cutolo, Fabrizio; Condino, Sara; Carbone, Marina; Siesto, Mentore; Ferrari, Mauro

2016-06-01

Surgical simulation based on augmented reality (AR), mixing the benefits of physical and virtual simulation, represents a step forward in surgical training. However, available systems are unable to update the virtual anatomy following deformations impressed on actual anatomy. A proof-of-concept solution is described providing AR visualization of hidden deformable tubular structures using nitinol tubes sensorized with electromagnetic sensors. This system was tested in vitro on a setup comprised of sensorized cystic, left and right hepatic, and proper hepatic arteries. In the trial session, the surgeon deformed the tubular structures with surgical forceps in 10 positions. The mean, standard deviation, and maximum misalignment between virtual and real arteries were 0.35, 0.22, and 0.99 mm, respectively. The alignment accuracy obtained demonstrates the feasibility of the approach, which can be adopted in advanced AR simulations, in particular as an aid to the identification and isolation of tubular structures. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Insecticidal activity of Leptodactylus knudseni and Phyllomedusa vaillantii crude skin secretions against the mosquitoes Anopheles darlingi and Aedes aegypti

PubMed Central

2014-01-01

Background Mosquitoes are important vectors of several diseases, including malaria and dengue, and control measures are mostly performed using chemical insecticides. Unfortunately, mosquito resistance to commonly applied insecticides is widespread. Therefore, a prospection for new molecules with insecticidal activity based on Amazon biodiversity using the anurans Leptodactylus knudseni and Phyllomedusa vaillantii was performed against the mosquito species Anopheles darlingi and Aedes aegypti. Methods The granular secretion from anuran skin was obtained by manual stimulation, and lethal concentrations (LCs) for larvicidal and adulticidal tests were calculated using concentrations from 1-100 ppm. The skin secretions from the anuran species tested caused significant mortality within the first 24 hours on adults and larvae, but differed within the mosquito species. Results The skin secretions from the anuran species tested caused significant mortality within the first 24 hours on adults and larvae, but differed within the mosquito species. The calculated LC50 of L. knudseni skin secretions against An. darlingi was 0.15 and 0.2 ppm for adults and larvae, respectively, but much higher for Ae. aegypti, i.e., 19 and 38 ppm, respectively. Interestingly, the calculated LCs50 of P. vaillantii against both mosquito species in adults were similar, 1.8 and 2.1 ppm, respectively, but the LC50 for An. darlingi larvae was much lower (0.4 ppm) than for Ae aegypti (2.1 ppm). Conclusions The present experiments indicate that skin secretions from L. knudseni and P. vaillantii contain bioactive molecules with potent insecticide activity. The isolation and characterization of skin secretions components will provide new insights for potential insecticidal molecules. PMID:25165469

Thermal sprayed composite melt containment tubular component and method of making same

DOEpatents

Besser, Matthew F.; Terpstra, Robert L.; Sordelet, Daniel J.; Anderson, Iver E.

2002-03-19

A tubular thermal sprayed melt containment component for transient containment of molten metal or alloy wherein the tubular member includes a thermal sprayed inner melt-contacting layer for contacting molten metal or alloy to be processed, a thermal sprayed heat-generating layer deposited on the inner layer, and an optional thermal sprayed outer thermal insulating layer. The thermal sprayed heat-generating layer is inductively heated as a susceptor of an induction field or electrical resistively heated by passing electrical current therethrough. The tubular thermal sprayed melt containment component can comprise an elongated melt pour tube of a gas atomization apparatus where the melt pour tube supplies molten material from a crucible to an underlying melt atomization nozzle.

Phosphorylation of Stats at Ser727 in renal proximal tubular epithelial cells exposed to cadmium.

PubMed

Nakagawa, Junko; Nishitai, Gen; Inageda, Kiyoshi; Matsuoka, Masato

2007-11-01

The effects of cadmium exposure on serine phosphorylation of signal transducers and activators of transcription (Stats) and an upstream kinase were examined in renal proximal tubular cells. In porcine LLC-PK1 cells treated with cadmium, Stat1 and Stat3 proteins were phosphorylated at Ser727 without changing total Stat protein levels. While phosphorylated forms of the members of mitogen-activated protein kinases (MAPKs) increased in response to cadmium exposure, treatment with a p38 inhibitor, SB203580 reduced Ser727 phosphorylation of Stat1 and Stat3 markedly in LLC-PK1 cells. The expression of human matrix metalloproteinase-3 (MMP-3), a Stats-inducible gene, was found to be up-regulated in human HK-2 cells exposed to cadmium, and suppressed by preincubation with SB203580. These results suggest that cadmium might induce the phosphorylation of Stat1 and Stat3 at Ser727 via the p38 pathway at least in part, and modulate gene expression in these proximal tubular cells. Copyright © 2007 Elsevier B.V. All rights reserved.

Pituitary adenylate cyclase-activating polypeptide is a potent inhibitor of the growth of light chain-secreting human multiple myeloma cells.

PubMed

Li, Min; Cortez, Shirley; Nakamachi, Tomoya; Batuman, Vecihi; Arimura, Akira

2006-09-01

Multiple myeloma represents a malignant proliferation of plasma cells in the bone marrow, which often overproduces immunoglobulin light chains. We have shown previously that pituitary adenylate cyclase-activating polypeptide (PACAP) markedly suppresses the release of proinflammatory cytokines from light chain-stimulated human renal proximal tubule epithelial cells and prevents the resulting tubule cell injury. In this study, we have shown that PACAP suppresses the proliferation of human kappa and lambda light chain-secreting multiple myeloma-derived cells. The addition of PACAP suppressed light chain-producing myeloma cell-stimulated interleukin 6 (IL-6) secretion by the bone marrow stromal cells (BMSCs). A specific antagonist to either the human PACAP-specific receptor or the vasoactive intestinal peptide receptor attenuated the suppressive effect of PACAP on IL-6 production in the adhesion of human multiple myeloma cells to BMSCs. The secretion of IL-6 by BMSCs was completely inhibited by 10(-9) mol/L PACAP, which also attenuated the phosphorylation of both p42/44 and p38 mitogen-activated protein kinases (MAPK) as well as nuclear factor-kappaB (NF-kappaB) activation in response to the adhesion of multiple myeloma cells to BMSCs, whereas the inhibition of p42/44 MAPK signaling attenuated PACAP action. The signaling cascades involved in the inhibitory effect of PACAP on IL-6-mediated paracrine stimulation of light chain-secreting myeloma cell growth was mediated through the suppression of p38 MAPK as well as modulation of activation of transcription factor NF-kappaB. These findings suggest that PACAP may be a new antitumor agent that directly suppresses light chain-secreting myeloma cell growth and indirectly affects tumor cell growth by modifying the bone marrow milieu of the multiple myeloma.

Endosomal accumulation of Toll-like receptor 4 causes constitutive secretion of cytokines and activation of signal transducers and activators of transcription in Niemann-Pick disease type C (NPC) fibroblasts: a potential basis for glial cell activation in the NPC brain.

PubMed

Suzuki, Michitaka; Sugimoto, Yuko; Ohsaki, Yuki; Ueno, Makoto; Kato, Shinsuke; Kitamura, Yukisato; Hosokawa, Hiroshi; Davies, Joanna P; Ioannou, Yiannis A; Vanier, Marie T; Ohno, Kousaku; Ninomiya, Haruaki

2007-02-21

Niemann-Pick disease type C (NPC) is an inherited lipid storage disorder caused by mutations in NPC1 or NPC2 genes. Loss of function of either protein results in the endosomal accumulation of cholesterol and other lipids, progressive neurodegeneration, and robust glial cell activation. Here, we report that cultured human NPC fibroblasts secrete interferon-beta, interleukin-6 (IL-6), and IL-8, and contain increased levels of signal transducers and activators of transcription (STATs). These cells also contained increased levels of Toll-like receptor 4 (TLR4) that accumulated in cholesterol-enriched endosomes/lysosomes, and small interfering RNA knockdown of this receptor reduced cytokine secretion. In the NPC1-/- mouse brain, glial cells expressed TLR4 and IL-6, whereas both glial and neuronal cells expressed STATs. Genetic deletion of TLR4 in NPC1-/- mice reduced IL-6 secretion by cultured fibroblasts but failed to alter STAT levels or glial cell activation in the brain. In contrast, genetic deletion of IL-6 normalized STAT levels and suppressed glial cell activation. These findings indicate that constitutive cytokine secretion leads to activation of STATs in NPC fibroblasts and that this secretion is partly caused by an endosomal accumulation of TLR4. These results also suggest that similar signaling events may underlie glial cell activation in the NPC1-/- mouse brain.

Unfolding the relationship between secreted molecular chaperones and macrophage activation states

PubMed Central

Henderson, Samantha

2008-01-01

Over the last 20 years, it has emerged that many molecular chaperones and protein-folding catalysts are secreted from cells and function, somewhat in the manner of cytokines, as pleiotropic signals for a variety of cells, with much attention being focused on the macrophage. During the last decade, it has become clear that macrophages respond to bacterial, protozoal, parasitic and host signals to generate phenotypically distinct states of activation. These activation states have been termed ‘classical’ and ‘alternative’ and represent not a simple bifurcation in response to external signals but a range of cellular phenotypes. From an examination of the literature, the hypothesis is propounded that mammalian molecular chaperones are able to induce a wide variety of alternative macrophage activation states, and this may be a system for relating cellular or tissue stress to appropriate macrophage responses to restore homeostatic equilibrium. PMID:18958583

Vesicle-mediated growth of tubular branches and centimeter-long microtubes from a single molecule.

PubMed

Abbas, Abdennour; Brimer, Andrew; Tian, Limei; d'Avignon, D André; Hameed, Abdulrahman Shahul; Vittal, Jagadese J; Singamaneni, Srikanth

2013-08-12

The mechanism by which small molecules assemble into microscale tubular structures in aqueous solution remains poorly understood, particularly when the initial building blocks are non-amphiphilic molecules and no surfactant is used. It is here shown how a subnanometric molecule, namely p-aminothiophenol (p-ATP), prepared in normal water with a small amount of ethanol, spontaneously assembles into a new class of nanovesicle. Due to Brownian motion, these nanostructures rapidly grow into micrometric vesicles and start budding to yield macroscale tubular branches with a remarkable growth rate of ∼20 μm s⁻¹. A real-time visualization by optical microscopy reveals that tubular growth proceeds by vesicle walk and fusion on the apex (growth cone) and sides of the branches and ultimately leads to the generation of centimeter-long microtubes. This unprecedented growth mechanism is triggered by a pH-activated proton switch and maintained by hydrogen bonding. The vesicle fusion-mediated synthesis suggests that functional microtubes with biological properties can be efficiently prepared with a mixture of appropriate diaminophenyl blocks and the desired macromolecule. The reversibility, timescale, and very high yield (90%) of this synthetic approach make it a valuable model for the investigation of hierarchical and structural transition between organized assemblies with different size scales and morphologies. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Activation of AMPK Inhibits Cholera Toxin Stimulated Chloride Secretion in Human and Murine Intestine

PubMed Central

Hoekstra, Nadia; Collins, Danielle; Collaco, Anne; Baird, Alan W.; Winter, Desmond C.; Ameen, Nadia; Geibel, John P.; Kopic, Sascha

2013-01-01

Increased intestinal chloride secretion through chloride channels, such as the cystic fibrosis transmembrane conductance regulator (CFTR), is one of the major molecular mechanisms underlying enterotoxigenic diarrhea. It has been demonstrated in the past that the intracellular energy sensing kinase, the AMP-activated protein kinase (AMPK), can inhibit CFTR opening. We hypothesized that pharmacological activation of AMPK can abrogate the increased chloride flux through CFTR occurring during cholera toxin (CTX) mediated diarrhea. Chloride efflux was measured in isolated rat colonic crypts using real-time fluorescence imaging. AICAR and metformin were used to activate AMPK in the presence of the secretagogues CTX or forskolin (FSK). In order to substantiate our findings on the whole tissue level, short-circuit current (SCC) was monitored in human and murine colonic mucosa using Ussing chambers. Furthermore, fluid accumulation was measured in excised intestinal loops. CTX and forskolin (FSK) significantly increased chloride efflux in isolated colonic crypts. The increase in chloride efflux could be offset by using the AMPK activators AICAR and metformin. In human and mouse mucosal sheets, CTX and FSK increased SCC. AICAR and metformin inhibited the secretagogue induced rise in SCC, thereby confirming the findings made in isolated crypts. Moreover, AICAR decreased CTX stimulated fluid accumulation in excised intestinal segments. The present study suggests that pharmacological activation of AMPK effectively reduces CTX mediated increases in intestinal chloride secretion, which is a key factor for intestinal water accumulation. AMPK activators may therefore represent a supplemental treatment strategy for acute diarrheal illness. PMID:23935921

[ERK activation effects on GABA secretion inhibition induced by SDF-1 in hippocampal neurons of rats].

PubMed

Zhang, Zi-juan; Guo, Mei-xia; Xing, Ying

2015-09-01

To investigate the effect of extracellular regulating kinase (ERK) signaling pathway on the secretion of gamma-aminobutyric acid (GABA) in cultured rat hippocampal neurons induced by stromal cell derived factor-1 (SDF-1). The hippocampal neurons of newborn SD rats were cultured and identified in vitro; the phosphorylation level of ERK1/2 was examined by Western blot; ELISA was used to detect the effect of PD98059, a ERK1/2 specific blocker on GABA secretion of cultured hippocampal neurons and Western blot were adopted to measure the protein expression levels of glutamate decarboxylase (GAD65/67) and gamma aminobutyric acid transporter (GAT); after blocking ERK1/2 signaling pathway with PD98059; RT-PCR was used to detect the mRNA expression levels of GAT-1 and GAD65 after treated with PD98059. The levels of ERKl/2 phosphorylation were increased significantly by SDF1 acting on hippocampal neurons, and CX-CR4 receptor blocker AMD3100, could inhibit SDF-1 induced ERK1/2 activation; SDF-1 could inhibit the secretion of GABA in cultured hippocampal neurons, and ERK1/2 specific inhibitor PD98059, could partly reverse the inhibition of GABA secretion by SDF-1. The effects of SDF-1 on cultured hippocampal neurons was to decrease the mRNA genesis of glutamic acid decarboxylase GAD65 and GABA transporter GAT-1, besides, ERK inhibitor PD98059 could effectively flip the effect of SDF-1. The results of Western blot showed that SDF-1 could inhibit the protein expression of GAT-1 and GAD65/67 in hippocampal neurons and the inhibition of GAT-1 and GAD65/67 protein expression could be partially restored by ERK1/2 blocker. SDF-1 acts on the CXCR4 of hippocampal neurons in vitro, and inhibits the expression of GAD by activating the ERK1/2 signaling pathway, and this may represent one possible pathway of GABA secretion inhibition.

Direct cell-cell contact activates SigM to express the ESX-4 secretion system in Mycobacterium smegmatis.

PubMed

Clark, Ryan R; Judd, Julius; Lasek-Nesselquist, Erica; Montgomery, Sarah A; Hoffmann, Jennifer G; Derbyshire, Keith M; Gray, Todd A

2018-06-25

Conjugal cell-cell contact between strains of Mycobacterium smegmatis induces the esxUT transcript, which encodes the putative primary substrates of the ESAT-6 secretion system 4 (ESX-4) secretion system. This recipient response was required for conjugal transfer of chromosomal DNA from the donor strain. Here we show that the extracytoplasmic σ factor, SigM, is a cell contact-dependent activator of ESX-4 expression and is required for conjugal transfer of DNA in the recipient strain. The SigM regulon includes genes outside the seven-gene core esx4 locus that we show are also required for conjugation, and we show that some of these SigM-induced proteins likely function through ESX-4. A fluorescent reporter revealed that SigM is specifically activated in recipient cells in direct contact with donor cells. Coculture RNA-seq experiments indicated that SigM regulon induction occurred early and before transconjugants are detected. This work supports a model wherein donor contact with the recipient cell surface inactivates the transmembrane anti-SigM, thereby releasing SigM. Free SigM induces an extended ESX-4 secretion system, resulting in changes that facilitate chromosomal transfer. The contact-dependent inactivation of an extracytoplasmic σ-factor that tightly controls ESX-4 activity suggests a mechanism dedicated to detect, and appropriately respond to, external stimuli from mycobacteria.

Dynamics of catalytic tubular microjet engines: Dependence on geometry and chemical environment

NASA Astrophysics Data System (ADS)

LiJ. X. L.; G. S. H. Contributed Equally To This Work., Jinxing; Huang, Gaoshan; Ye, Mengmeng; Li, Menglin; Liu, Ran; Mei, Yongfeng

2011-12-01

Strain-engineered tubular microjet engines with various geometric dimensions hold interesting autonomous motions in an aqueous fuel solution when propelled by catalytic decomposition of hydrogen peroxide to oxygen and water. The catalytically-generated oxygen bubbles expelled from microtubular cavities propel the microjet step by step in discrete increments. We focus on the dynamics of our tubular microjets in one step and build up a body deformation model to elucidate the interaction between tubular microjets and the bubbles they produce. The average microjet velocity is calculated analytically based on our model and the obtained results demonstrate that the velocity of the microjet increases linearly with the concentration of hydrogen peroxide. The geometric dimensions of the microjet, such as length and radius, also influence its dynamic characteristics significantly. A close consistency between experimental and calculated results is achieved despite a small deviation due to the existence of an approximation in the model. The results presented in this work improve our understanding regarding catalytic motions of tubular microjets and demonstrate the controllability of the microjet which may have potential applications in drug delivery and biology.Strain-engineered tubular microjet engines with various geometric dimensions hold interesting autonomous motions in an aqueous fuel solution when propelled by catalytic decomposition of hydrogen peroxide to oxygen and water. The catalytically-generated oxygen bubbles expelled from microtubular cavities propel the microjet step by step in discrete increments. We focus on the dynamics of our tubular microjets in one step and build up a body deformation model to elucidate the interaction between tubular microjets and the bubbles they produce. The average microjet velocity is calculated analytically based on our model and the obtained results demonstrate that the velocity of the microjet increases linearly with the

P2Y6 receptor mediates colonic NaCl secretion via differential activation of cAMP-mediated transport

PubMed Central

Köttgen, Michael; Löffler, Thomas; Jacobi, Christoph; Nitschke, Roland; Pavenstädt, Hermann; Schreiber, Rainer; Frische, Sebastian; Nielsen, Søren; Leipziger, Jens

2003-01-01

Extracellular nucleotides are important regulators of epithelial ion transport. Here we investigated nucleotide-mediated effects on colonic NaCl secretion and the signal transduction mechanisms involved. Basolateral UDP induced a sustained activation of Cl– secretion, which was completely inhibited by 293B, a specific inhibitor of cAMP-stimulated basolateral KCNQ1/KCNE3 K+ channels. We therefore speculated that a basolateral P2Y6 receptor could increase cAMP. Indeed UDP elevated cAMP in isolated crypts. We identified an epithelial P2Y6 receptor using crypt [Ca2+]i measurements, RT-PCR, and immunohistochemistry. To investigate whether the rat P2Y6elevates cAMP, we coexpressed the P2Y1 or P2Y6 receptor together with the cAMP-regulated cystic fibrosis transmembrane conductance regulator (CFTR) Cl– channel in Xenopus oocytes. A two-electrode voltage clamp was used to monitor nucleotide-induced Cl– currents. In oocytes expressing the P2Y1 receptor, ATP transiently activated the endogenous Ca2+-activated Cl– current, but not CFTR. In contrast, in oocytes expressing the P2Y6receptor, UDP transiently activated the Ca2+-activated Cl– current and subsequently CFTR. CFTR Cl– currents were identified by their halide conductance sequence. In summary we find a basolateral P2Y6 receptor in colonic epithelial cells stimulating sustained NaCl secretion by way of a synergistic increase of [Ca2+]i and cAMP. In support of these data P2Y6 receptor stimulation differentially activates CFTR in Xenopus oocytes. PMID:12569163

Large tubular colonic duplication in an adult treated with a small midline incision

PubMed Central

Yong, Yuen Geng; Jung, Kyung Uk; Cho, Yong Beom; Yun, Seong Hyeon; Kim, Hee Cheol; Lee, Woo Yong

2012-01-01

Tubular colonic duplication presenting in adults is rare and difficult to diagnose preoperatively. Only a few cases have been reported in the literature. We report a case of a 29-year-old lady presenting with a long history of chronic constipation, abdominal mass and repeated episodes of abdominal pain. The abdominal-pelvic computed tomography scan showed segmental bowel wall thickening thought to be small bowel, and dilatation with stasis of intraluminal content. The provisional diagnosis was small bowel duplication. She was scheduled for single port laparoscopic resection. However, a T-shaped tubular colonic duplication at sigmoid colon was found intraoperatively. Resection of the large T-shaped tubular colonic duplication containing multiple impacted large fecaloma and primary anastomosis was performed. There was no perioperative complication. We report, herein, the case of a T-shaped tubular colonic duplication at sigmoid colon in an adult who was successfully treated through mini-laparotomy assisted by single port laparoscopic surgery. PMID:22403754

RGMb protects against acute kidney injury by inhibiting tubular cell necroptosis via an MLKL-dependent mechanism.

PubMed

Liu, Wenjing; Chen, Binbin; Wang, Yang; Meng, Chenling; Huang, Huihui; Huang, Xiao-Ru; Qin, Jinzhong; Mulay, Shrikant R; Anders, Hans-Joachim; Qiu, Andong; Yang, Baoxue; Freeman, Gordon J; Lu, Hua Jenny; Lin, Herbert Y; Zheng, Zhi-Hua; Lan, Hui-Yao; Huang, Yu; Xia, Yin

2018-02-13

Tubular cell necrosis is a key histological feature of acute kidney injury (AKI). Necroptosis is a type of programed necrosis, which is executed by mixed lineage kinase domain-like protein (MLKL) upon its binding to the plasma membrane. Emerging evidence indicates that necroptosis plays a critical role in the development of AKI. However, it is unclear whether renal tubular cells undergo necroptosis in vivo and how the necroptotic pathway is regulated during AKI. Repulsive guidance molecule (RGM)-b is a member of the RGM family. Our previous study demonstrated that RGMb is highly expressed in kidney tubular epithelial cells, but its biological role in the kidney has not been well characterized. In the present study, we found that RGMb reduced membrane-associated MLKL levels and inhibited necroptosis in cultured cells. During ischemia/reperfusion injury (IRI) or oxalate nephropathy, MLKL was induced to express on the apical membrane of proximal tubular (PT) cells. Specific knockout of Rgmb in tubular cells (Rgmb cKO) increased MLKL expression at the apical membrane of PT cells and induced more tubular cell death and more severe renal dysfunction compared with wild-type mice. Treatment with the necroptosis inhibitor Necrostatin-1 or GSK'963 reduced MLKL expression on the apical membrane of PT cells and ameliorated renal function impairment after IRI in both wild-type and Rgmb cKO mice. Taken together, our results suggest that proximal tubular cell necroptosis plays an important role in AKI, and that RGMb protects against AKI by inhibiting MLKL membrane association and necroptosis in proximal tubular cells.

High-temperature, high-pressure bonding of nested tubular metallic components

DOEpatents

Quinby, T.C.

A tool is described for effecting high-temperature, high-compression bonding between the confronting faces of nested, tubular, metallic components. In a typical application, the tool is used to produce tubular target assemblies for irradiation in nuclear reactors or particle accelerators. The target assembly comprising a uranum foil and an aluninum-alloy substrate. The tool is composed of graphite. It comprises a tubular restraining member in which a mechanically expandable tubular core is mounted to form an annulus. The components to be bonded are mounted in nested relation in the annulus. The expandable core is formed of individually movable, axially elongated segments whose outer faces cooperatively define a cylindrical pressing surface and whose inner faces cooperatively define two opposed, inwardly tapered, axial bores. Tapered rams extend into the bores. The loaded tool is mounted in a conventional hot-press provided with evacuation means, heaters for maintaining its interior at bonding temperature, and hydraulic cylinders for maintaining a selected inwardly directed pressure on the tapered rams. With the hot-press evacuated and the loaded tool at the desired temperature, the cylinders are actuated to apply the selected pressure to the rams. The rams in turn expand the segmented core to maintain the nested components in compression against the restraining member. These conditions are maintained until the confronting faces of the nested components are joined in a continuous, uniform bond characterized by high thermal conductivity.

High-temperature, high-pressure bonding of nested tubular metallic components

DOEpatents

Quinby, Thomas C.

1980-01-01

This invention is a tool for effecting high-temperature, high-compression bonding between the confronting faces of nested, tubular, metallic components. In a typical application, the tool is used to produce tubular target assemblies for irradiation in nuclear reactors or particle accelerators, the target assembly comprising a uranium foil and an aluminum-alloy substrate. The tool preferably is composed throughout of graphite. It comprises a tubular restraining member in which a mechanically expandable tubular core is mounted to form an annulus with the member. The components to be bonded are mounted in nested relation in the annulus. The expandable core is formed of individually movable, axially elongated segments whose outer faces cooperatively define a cylindrical pressing surface and whose inner faces cooperatively define two opposed, inwardly tapered, axial bores. Tapered rams extend respectively into the bores. The loaded tool is mounted in a conventional hot-press provided with evacuation means, heaters for maintaining its interior at bonding temperature, and hydraulic cylinders for maintaining a selected inwardly directed pressure on the tapered rams. With the hot-press evacuated and the loaded tool at the desired temperature, the cylinders are actuated to apply the selected pressure to the rams. The rams in turn expand the segmented core to maintain the nested components in compression against the restraining member. These conditions are maintained until the confronting faces of the nested components are joined in a continuous, uniform bond characterized by high thermal conductivity.

Enteroaggregative Escherichia coli flagellin-induced interleukin-8 secretion requires Toll-like receptor 5-dependent p38 MAP kinase activation

PubMed Central

Khan, Mohammed A S; Kang, Jian; Steiner, Theodore S

2004-01-01

Enteroaggregative Escherichia coli (EAEC) is an emerging enteric pathogen that causes acute and chronic diarrhoea in a number of clinical settings. EAEC diarrhoea involves bacterial aggregation, adherence to intestinal epithelial cells and elaboration of several toxigenic bacterial mediators. Flagellin (FliC-EAEC), a major bacterial surface protein of EAEC, causes interleukin (IL)-8 release from several epithelial cell lines. The host response to flagellins from E. coli and several other bacteria is mediated by Toll-like receptor 5 (TLR5), which signals through nuclear factor kappa B (NF-κB) to induce transcription of pro-inflammatory cytokines. p38 mitogen-activating protein (MAP) kinase (MAPK) is a member of a family of stress-related kinases that influences a diverse range of cellular functions including host inflammatory responses to microbial products. We studied the role of p38 MAPK in FliC-EAEC-induced IL-8 secretion from Caco-2 human intestinal epithelial cells and THP-1 human monocytic cells. We found that IL-8 secretion from both cell types is dependent on p38 MAPK, which is phospho-activated in response to FliC-EAEC. The role of TLR5 in p38 MAPK-dependent IL-8 secretion was verified in HEp-2 cells transiently transfected with a TLR5 expression construct. Activation of interleukin-1 receptor-associated kinase (IRAK) was also observed in Caco-2 and TLR5-transfected HEp-2 cells after exposure to FliC-EAEC. Finally, we demonstrated that pharmacological inhibition of p38 MAPK reduced IL-8 transcription and mRNA levels, but did not affect NF-κB activation. Collectively, our results suggest that TLR5 mediates p38 MAPK-dependent IL-8 secretion from epithelial and monocytic cells incubated with FliC-EAEC, and that this effect requires IL-8 promoter activation independent of NF-κB nuclear migration. PMID:15270737

Ocimum grastissimum extract inhibits stimulated acid secretion by carbachol and induces gastric mucus secretion.

PubMed

Onasanwo, S A; Omolaso, B O; Ukoha, N

2012-12-01

In this study, the effects of ethanol extract of Ocimum gratissimum (EEOG) on both basal and stimulated gastric acid secretion and gastric mucus secretion were investigated in Albino rats treated with the extract. Four groups of animals were used. Sub-group 1A serves as control. Animals in Group 2A, 3B and 4B were pretreated with 200 mg/kg of (E3EOG) for 1, 7 and 14 days respectively. Basal gastric effluents were collected from all the groups of animals at intervals of 10 mins for 60 mins. Thereafter, Subgroups 1A, 2A, 3A and 4A were administered with 50 micro/kg b.w. of carbachol (i.p.) intraperitonialy and effluents collected. Animals in Sub-group B were used for gastric mucus study. Carbachol stimulates gastric acid secretion in animals pretreated with the extract for 1, 7 and 14 days. 50-400 mg/kg b.w. doses of the extract significantly increase gastric mucus secretion. These results indicate the mechanism of anti-ulcer activity of the extract may be due to stimulation of gastric mucus secretion amongst pathways.

Synthesis and adsorption properties of hollow tubular alumina fibers

NASA Astrophysics Data System (ADS)

Lozhkomoev, A. S.; Kazantsev, S. O.; Glazkova, E. A.

2017-12-01

In this study, composite glass fibers coated with alumina nanoplates and hollow tubular alumina fibers with a diameter of 400-500 nm are synthesized based on glass fiber templated hydrothermal strategy. Porous coatings on glass fibers and hollow fibers consist of cross-linked alumina nanoplates with the size of 100-200 nm and thickness of 2-5 nm. Their formation is attributed to the template-induced heterogeneous growth of alumina nanoplates on glass fibers of the B-06-F type. It is important that composite glass fibers and hollow tubular fibers have opposite surface charges and exhibit selective sorption characteristics towards anionic and cationic dyes.

Hot fire test results of subscale tubular combustion chambers

NASA Technical Reports Server (NTRS)

Kazaroff, John M.; Jankovsky, Robert S.; Pavli, Albert J.

1992-01-01

Advanced, subscale, tubular combustion chambers were built and test fired with hydrogen-oxygen propellants to assess the increase in fatigue life that can be obtained with this type of construction. Two chambers were tested: one ran for 637 cycles without failing, compared to a predicted life of 200 cycles for a comparable smooth-wall milled-channel liner configuration. The other chamber failed at 256 cycles, compared to a predicted life of 118 cycles for a comparable smooth-wall milled-channel liner configuration. Posttest metallographic analysis determined that the strain-relieving design (structural compliance) of the tubular configuration was the cause of this increase in life.

Cyclosporin A Impairs the Secretion and Activity of ADAMTS13 (A Disintegrin and Metalloprotease with Thrombospondin Type 1 Repeat)*

PubMed Central

Hershko, Klilah; Simhadri, Vijaya L.; Blaisdell, Adam; Hunt, Ryan C.; Newell, Jordan; Tseng, Sandra C.; Hershko, Alon Y.; Choi, Jae Won; Sauna, Zuben E.; Wu, Andrew; Bram, Richard J.; Komar, Anton A.; Kimchi-Sarfaty, Chava

2012-01-01

The protease ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 repeat) cleaves multimers of von Willebrand factor, thus regulating platelet aggregation. ADAMTS13 deficiency leads to the fatal disorder thrombotic thrombocytopenic purpura (TTP). It has been observed that cyclosporin A (CsA) treatment, particularly in transplant patients, may sometimes be linked to the development of TTP. Until now, the reason for such a link was unclear. Here we provide evidence demonstrating that cyclophilin B (CypB) activity plays an important role in the secretion of active ADAMTS13. We found that CsA, an inhibitor of CypB, reduces the secretion of ADAMTS13 and leads to conformational changes in the protein resulting in diminished ADAMTS13 proteolytic activity. A direct, functional interaction between CypB (which possesses peptidyl-prolyl cis-trans isomerase (PPIase) and chaperone functions) and ADAMTS13 is demonstrated using immunoprecipitation and siRNA knockdown of CypB. Finally, CypB knock-out mice were found to have reduced ADAMTS13 levels. Taken together, our findings indicate that cyclophilin-mediated activity is an important factor affecting secretion and activity of ADAMTS13. The large number of proline residues in ADAMTS13 is consistent with the important role of cis-trans isomerization in the proper folding of this protein. These results altogether provide a novel mechanistic explanation for CsA-induced TTP in transplant patients. PMID:23144461

Cyclosporin A impairs the secretion and activity of ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 repeat).

PubMed

Hershko, Klilah; Simhadri, Vijaya L; Blaisdell, Adam; Hunt, Ryan C; Newell, Jordan; Tseng, Sandra C; Hershko, Alon Y; Choi, Jae Won; Sauna, Zuben E; Wu, Andrew; Bram, Richard J; Komar, Anton A; Kimchi-Sarfaty, Chava

2012-12-28

The protease ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 repeat) cleaves multimers of von Willebrand factor, thus regulating platelet aggregation. ADAMTS13 deficiency leads to the fatal disorder thrombotic thrombocytopenic purpura (TTP). It has been observed that cyclosporin A (CsA) treatment, particularly in transplant patients, may sometimes be linked to the development of TTP. Until now, the reason for such a link was unclear. Here we provide evidence demonstrating that cyclophilin B (CypB) activity plays an important role in the secretion of active ADAMTS13. We found that CsA, an inhibitor of CypB, reduces the secretion of ADAMTS13 and leads to conformational changes in the protein resulting in diminished ADAMTS13 proteolytic activity. A direct, functional interaction between CypB (which possesses peptidyl-prolyl cis-trans isomerase (PPIase) and chaperone functions) and ADAMTS13 is demonstrated using immunoprecipitation and siRNA knockdown of CypB. Finally, CypB knock-out mice were found to have reduced ADAMTS13 levels. Taken together, our findings indicate that cyclophilin-mediated activity is an important factor affecting secretion and activity of ADAMTS13. The large number of proline residues in ADAMTS13 is consistent with the important role of cis-trans isomerization in the proper folding of this protein. These results altogether provide a novel mechanistic explanation for CsA-induced TTP in transplant patients.

A novel angiotensin II type 1 receptor-associated protein induces cellular hypertrophy in rat vascular smooth muscle and renal proximal tubular cells.

PubMed

Guo, Deng-Fu; Tardif, Valerie; Ghelima, Karin; Chan, John S D; Ingelfinger, Julie R; Chen, XiangMei; Chenier, Isabelle

2004-05-14

Angiotensin II stimulates cellular hypertrophy in cultured vascular smooth muscle and renal proximal tubular cells. This effect is believed to be one of earliest morphological changes of heart and renal failure. However, the precise molecular mechanism involved in angiotensin II-induced hypertrophy is poorly understood. In the present study we report the isolation of a novel angiotensin II type 1 receptor-associated protein. It encodes a 531-amino acid protein. Its mRNA is detected in all human tissues examined but highly expressed in the human kidney, pancreas, heart, and human embryonic kidney cells as well as rat vascular smooth muscle and renal proximal tubular cells. Protein synthesis and relative cell size analyzed by flow cytometry studies indicate that overexpression of the novel angiotensin II type 1 receptor-associated protein induces cellular hypertrophy in cultured rat vascular smooth muscle and renal proximal tubular cells. In contrast, the hypertrophic effects was reversed in renal proximal tubular cell lines expressing the novel gene in the antisense orientation and its dominant negative mutant, which lacks the last 101 amino acids in its carboxyl-terminal tail. The hypertrophic effects are at least in part mediated via protein kinase B activation or cyclin-dependent kinase inhibitor, p27(kip1) protein expression level in vascular smooth muscle, and renal proximal tubular cells. Moreover, angiotensin II could not stimulate cellular hypertrophy in renal proximal tubular cells expressing the novel gene in the antisense orientation and its mutant. These findings may provide new molecular mechanisms to understand hypertrophic agents such as angiotensin II-induced cellular hypertrophy.

Spermidine rescues proximal tubular cells from oxidative stress and necrosis after ischemic acute kidney injury.

PubMed

Kim, Jinu

2017-10-01

Kidney ischemia and reperfusion injury (IRI) is associated with a high mortality rate, which is attributed to tubular oxidative stress and necrosis; however, an effective approach to limit IRI remains elusive. Spermidine, a naturally occurring polyamine, protects yeast cells against aging through the inhibition of oxidative stress and necrosis. In the present study, spermidine supplementation markedly attenuated increases in plasma creatinine concentration and tubular injury score after IRI. In addition, exogenous spermidine potently inhibited oxidative stress, especially lipid peroxidation after IRI in kidneys and exposure to hydrogen peroxide in kidney proximal tubular cells, suppressing plasma membrane disruption and necrosis. Consistent with spermidine supplementation, upregulation of ornithine decarboxylase (ODC) in human kidney proximal tubular cells significantly diminished lipid peroxidation and necrosis induced by hydrogen peroxide-induced injury. Conversely, ODC deficiency significantly enhanced lipid peroxidation and necrosis after exposure to hydrogen peroxide. Finally, small interfering RNA-mediated ODC inhibition induced functional and histological damage in kidneys as well as it increased lipid hydroperoxide levels after IRI. In conclusion, these data suggest that spermidine level determines kidney proximal tubular damage through oxidative stress and necrosis induced by IRI, and this finding provides a novel target for prevention of tubular damage induced by IRI.

Dietary protein-induced hepatic IGF-1 secretion mediated by PPARγ activation.

PubMed

Wan, Xiaojuan; Wang, Songbo; Xu, Jingren; Zhuang, Lu; Xing, Kongping; Zhang, Mengyuan; Zhu, Xiaotong; Wang, Lina; Gao, Ping; Xi, Qianyun; Sun, Jiajie; Zhang, Yongliang; Li, Tiejun; Shu, Gang; Jiang, Qingyan

2017-01-01

Dietary protein or amino acid (AA) is a crucial nutritional factor to regulate hepatic insulin-like growth factor-1 (IGF-1) expression and secretion. However, the underlying intracellular mechanism by which dietary protein or AA induces IGF-1 expression remains unknown. We compared the IGF-1 gene expression and plasma IGF-1 level of pigs fed with normal crude protein (CP, 20%) and low-protein levels (LP, 14%). RNA sequencing (RNA-seq) was performed to detect transcript expression in the liver in response to dietary protein. The results showed that serum concentrations and mRNA levels of IGF-1 in the liver were higher in the CP group than in the LP group. RNA-seq analysis identified a total of 1319 differentially expressed transcripts (667 upregulated and 652 downregulated), among which the terms "oxidative phosphorylation", "ribosome", "gap junction", "PPAR signaling pathway", and "focal adhesion" were enriched. In addition, the porcine primary hepatocyte and HepG2 cell models also demonstrated that the mRNA and protein levels of IGF-1 and PPARγ increased with the increasing AA concentration in the culture. The PPARγ activator troglitazone increased IGF-1 gene expression and secretion in a dose dependent manner. Furthermore, inhibition of PPARγ effectively reversed the effects of the high AA concentration on the mRNA expression of IGF-1 and IGFBP-1 in HepG2 cells. Moreover, the protein levels of IGF-1 and PPARγ, as well as the phosphorylation of mTOR, significantly increased in HepG2 cells under high AA concentrations. mTOR phosphorylation can be decreased by the mTOR antagonist, rapamycin. The immunoprecipitation results also showed that high AA concentrations significantly increased the interaction of mTOR and PPARγ. In summary, PPARγ plays an important role in the regulation of IGF-1 secretion and gene expression in response to dietary protein.

Chirality of Single-Handed Twisted Titania Tubular Nanoribbons Prepared Through Sol-gel Transcription.

PubMed

Wang, Sibing; Zhang, Chuanyong; Li, Yi; Li, Baozong; Yang, Yonggang

2015-08-01

Single-handed twisted titania tubular nanoribbons were prepared through sol-gel transcription using a pair of enantiomers. Handedness was controlled by that of the template. The obtained samples were characterized using field-emission electron microscopy, transmission electron microscopy, diffuse reflectance circular dichroism (DRCD), and X-ray diffraction. The DRCD spectra indicated that the titania nanotubes exhibit optical activity. Although the tubular structure was destroyed after being calcined at 700 °C for 2.0 h, DRCD signals were still identified. However, the DRCD signals disappeared after being calcined at 1000 °C for 2.0 h. The optical activity of titania was proposed to be due to chiral defects. Previous results showed that straight titania tubes could be used as asymmetric autocatalysts, indicating that titania exhibit chirality at the angstrom level. Herein, it was found that they also exhibit DRCD signals, indicating that there are no obvious relationships between morphology at the nano level and chirality at the angstrom level. The nanotube chirality should originate from the chiral defects on the nanotube inner surface. The Fourier transform infrared spectra indicated that the chirality of the titania was transferred from the gelators through the hydrogen bonding between N-H and Ti-OH. © 2015 Wiley Periodicals, Inc.

Reference values of renal tubular function tests are dependent on age and kidney function.

PubMed

Bech, Anneke P; Wetzels, Jack F M; Nijenhuis, Tom

2017-12-01

Electrolyte disorders due to tubular disorders are rare, and knowledge about validated clinical diagnostic tools such as tubular function tests is sparse. Reference values for tubular function tests are based on studies with small sample size in young healthy volunteers. Patients with tubular disorders, however, frequently are older and can have a compromised renal function. We therefore evaluated four tubular function tests in individuals with different ages and renal function. We performed furosemide, thiazide, furosemide-fludrocortisone, and desmopressin tests in healthy individuals aged 18-50 years, healthy individuals aged more than 50 years and individuals with compromised renal function. For each tubular function test we included 10 individuals per group. The responses in young healthy individuals were in line with previously reported values in literature. The maximal increase in fractional chloride excretion after furosemide was below the lower limit of young healthy individuals in 5/10 older subjects and in 2/10 patients with compromised renal function. The maximal increase in fractional chloride excretion after thiazide was below the lower limit of young healthy individuals in 6/10 older subjects and in 7/10 patients with compromised renal function. Median maximal urine osmolality after desmopressin was 1002 mosmol/kg H 2 O in young healthy individuals, 820 mosmol/kg H 2 O in older subjects and 624 mosmol/kg H 2 O in patients with compromised renal function. Reference values for tubular function tests obtained in young healthy adults thus cannot simply be extrapolated to older patients or patients with compromised kidney function. Larger validation studies are needed to define true reference values in these patient categories. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

The Tubular Penetration Depth and Adaption of Four Sealers: A Scanning Electron Microscopic Study

PubMed Central

Chen, Huan; Zhao, Xinyuan; Qiu, Yu; Xu, Dengyou

2017-01-01

Background. The tubular penetration and adaptation of the sealer are important factors for successful root canal filling. The aim of this study was to evaluate the tubular penetration depth of four different sealers in the coronal, middle, and apical third of root canals as well as the adaptation of these sealers to root canal walls. Materials and Methods. 50 single-rooted teeth were prepared in this study. Forty-eight of them were filled with different sealers (Cortisomol, iRoot SP, AH-Plus, and RealSeal SE) and respective core filling materials. Then the specimens were sectioned and scanning electron microscopy was employed to assess the tubular penetration and adaptation of the sealers. Results. Our results demonstrated that the maximum penetration was exhibited by RealSeal SE, followed by AH-Plus, iRoot SP, and Cortisomol. As regards the adaptation property to root canal walls, AH-Plus has best adaptation capacity followed by iRoot SP, RealSeal SE, and Cortisomol. Conclusion. The tubular penetration and adaptation vary with the different sealers investigated. RealSeal SE showed the most optimal tubular penetration, whereas AH-Plus presented the best adaptation to the root canal walls. PMID:29479539

Role of the Bacillus methanolicus citrate synthase II gene, citY, in regulating the secretion of glutamate in L-lysine-secreting mutants.

PubMed

Brautaset, Trygve; Williams, Mark D; Dillingham, Richard D; Kaufmann, Christine; Bennaars, Assumpta; Crabbe, Edward; Flickinger, Michael C

2003-07-01

The thermotolerant, restrictive methylotroph Bacillus methanolicus MGA3 (ATCC 53907) can secrete 55 g of glutamate per liter (maximum yield, 0.36 g/g) at 50 degrees C with methanol as a carbon source and a source of ammonia in fed-batch bioreactors. A homoserine dehydrogenase mutant, 13A52-8A66, secreting up to 35 g of L-lysine per liter in fed-batch fermentations had minimal 2-oxoglutarate dehydrogenase activity [7.3 nmol min(-1) (mg of protein)(-1)], threefold-increased pyruvate carboxylase activity [535 nmol min(-1) (mg of protein)(-1)], and elevated citrate synthase (CS) activity [292 nmol min(-1) (mg of protein)(-1)] and simultaneously secreted glutamate (20 to 30 g per liter) and L-lysine. The flow of carbon from oxaloacetate is split between transamination to aspartate and formation of citrate. To investigate the regulation of this branch point, the B. methanolicus gene citY encoding a CSII protein with activity at 50 degrees C was cloned from 13A52-8A66 into a CS-deficient Escherichia coli K2-1-4 strain. A citY-deficient B. methanolicus mutant, NCS-L-7, was also isolated from the parent strain of 13A52-8A66 by N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis, followed by selection with monofluoroacetate disks on glutamate plates. Characterization of these strains confirmed that citY in strain 13A52-8A66 was not altered and that B. methanolicus possessed several forms of CS. Analysis of citY cloned from NCS-L-7 showed that the reduced CS activity resulted from a frameshift mutation. The level of glutamate secreted by NCS-L-7 was reduced sevenfold and the ratio of L-lysine to glutamate secreted was increased 4.5-fold compared to the wild type in fed-batch cultures with glutamate feeding. This indicates that glutamate secretion in L-lysine-overproducing mutants can be altered in favor of increased L-lysine secretion by regulating in vivo CS activity.

Role of the Bacillus methanolicus Citrate Synthase II Gene, citY, in Regulating the Secretion of Glutamate in l-Lysine-Secreting Mutants

PubMed Central

Brautaset, Trygve; Williams, Mark D.; Dillingham, Richard D.; Kaufmann, Christine; Bennaars, Assumpta; Crabbe, Edward; Flickinger, Michael C.

2003-01-01

The thermotolerant, restrictive methylotroph Bacillus methanolicus MGA3 (ATCC 53907) can secrete 55 g of glutamate per liter (maximum yield, 0.36 g/g) at 50°C with methanol as a carbon source and a source of ammonia in fed-batch bioreactors. A homoserine dehydrogenase mutant, 13A52-8A66, secreting up to 35 g of l-lysine per liter in fed-batch fermentations had minimal 2-oxoglutarate dehydrogenase activity [7.3 nmol min−1 (mg of protein)−1], threefold-increased pyruvate carboxylase activity [535 nmol min−1 (mg of protein)−1], and elevated citrate synthase (CS) activity [292 nmol min−1 (mg of protein)−1] and simultaneously secreted glutamate (20 to 30 g per liter) and l-lysine. The flow of carbon from oxaloacetate is split between transamination to aspartate and formation of citrate. To investigate the regulation of this branch point, the B. methanolicus gene citY encoding a CSII protein with activity at 50°C was cloned from 13A52-8A66 into a CS-deficient Escherichia coli K2-1-4 strain. A citY-deficient B. methanolicus mutant, NCS-L-7, was also isolated from the parent strain of 13A52-8A66 by N-methyl-N′-nitro-N-nitrosoguanidine mutagenesis, followed by selection with monofluoroacetate disks on glutamate plates. Characterization of these strains confirmed that citY in strain 13A52-8A66 was not altered and that B. methanolicus possessed several forms of CS. Analysis of citY cloned from NCS-L-7 showed that the reduced CS activity resulted from a frameshift mutation. The level of glutamate secreted by NCS-L-7 was reduced sevenfold and the ratio of l-lysine to glutamate secreted was increased 4.5-fold compared to the wild type in fed-batch cultures with glutamate feeding. This indicates that glutamate secretion in l-lysine-overproducing mutants can be altered in favor of increased l-lysine secretion by regulating in vivo CS activity. PMID:12839772

Matrix Metalloproteinase-3 (MMP-3) Is an Endogenous Activator of the MMP-9 Secreted by Placental Leukocytes: Implication in Human Labor.

PubMed

Flores-Pliego, Arturo; Espejel-Nuñez, Aurora; Castillo-Castrejon, Marisol; Meraz-Cruz, Noemi; Beltran-Montoya, Jorge; Zaga-Clavellina, Veronica; Nava-Salazar, Sonia; Sanchez-Martinez, Maribel; Vadillo-Ortega, Felipe; Estrada-Gutierrez, Guadalupe

2015-01-01

The activity of matrix degrading enzymes plays a leading role in the rupture of the fetal membranes under normal and pathological human labor, and matrix metalloproteinase-9 (MMP-9) it is considered a biomarker of this event. To gain further insight into local MMP-9 origin and activation, in this study we analyzed the contribution of human placental leukocytes to MMP-9 secretion and explored the local mechanisms of the pro-enzyme activation. Placental blood leukocytes were obtained from women at term gestation without labor and maintained in culture up to 72 h. MMP-9 activity in the culture supernatants was determined by zymography and using a specific substrate. The presence of a potential pro-MMP-9 activator in the culture supernatants was monitored using a recombinant biotin-labeled human pro-MMP-9. To characterize the endogenous pro-MMP-9 activator, MMP-1, -3, -7 and -9 were measured by multiplex assay in the supernatants, and an inhibition assay of MMP-9 activation was performed using an anti-human MMP-3 and a specific MMP-3 inhibitor. Finally, production of MMP-9 and MMP-3 in placental leukocytes obtained from term pregnancies with and without labor was assessed by immunofluorescence. Placental leukocytes spontaneously secreted pro-MMP-9 after 24 h of culture, increasing significantly at 48 h (P≤0.05), when the active form of MMP-9 was detected. Culture supernatants activated the recombinant pro-MMP-9 showing that placental leukocytes secrete the activator. A significant increase in MMP-3 secretion by placental leukocytes was observed since 48 h in culture (P≤0.05) and up to 72 h (P≤0.001), when concentration reached its maximum value. Specific activity of MMP-9 decreased significantly (P≤0.005) when an anti-MMP-3 antibody or a specific MMP-3 inhibitor were added to the culture media. Placental leukocytes from term labor produced more MMP-9 and MMP-3 compared to term non-labor cells. In this work we confirm that placental leukocytes from human term

Disruption of gap junctions attenuates aminoglycoside-elicited renal tubular cell injury

PubMed Central

Yao, Jian; Huang, Tao; Fang, Xin; Chi, Yuan; Zhu, Ying; Wan, Yigang; Matsue, Hiroyuki; Kitamura, Masanori

2010-01-01

BACKGROUND AND PURPOSE Gap junctions play important roles in the regulation of cell phenotype and in determining cell survival after various insults. Here, we investigated the role of gap junctions in aminoglycoside-induced injury to renal tubular cells. EXPERIMENTAL APPROACH Two tubular epithelial cell lines NRK-E52 and LLC-PK1 were compared for gap junction protein expression and function by immunofluorescent staining, Western blot and dye transfer assay. Cell viability after exposure to aminoglycosides was evaluated by WST assay. Gap junctions were modulated by transfection of the gap junction protein, connexin 43 (Cx43), use of Cx43 siRNA and gap junction inhibitors. KEY RESULTS NRK-E52 cells expressed abundant Cx43 and were functionally coupled by gap junctional intercellular communication (GJIC). Exposure of NRK-E52 cells to aminoglycosides, G418 and hygromycin, increased Cx43 phosphorylation and GJIC. The aminoglycosides also decreased cell viability that was prevented by gap junction inhibitors and Cx43 siRNA. LLC-PK1 cells were gap junction-deficient and resistant to aminoglycoside-induced cytotoxicity. Over-expression of a wild-type Cx43 converted LLC-PK1 cells to a drug-sensitive phenotype. The gap junction inhibitor α-glycyrrhetinic acid (α-GA) activated Akt in NRK-E52 cells. Inhibition of the Akt pathway enhanced cell toxicity to G418 and abolished the protective effects of α-GA. In addition, gentamycin-elicited cytotoxicity in NRK-E52 cells was also significantly attenuated by α-GA. CONCLUSION AND IMPLICATIONS Gap junctions contributed to the cytotoxic effects of aminoglycosides. Modulation of gap junctions could be a promising approach for prevention and treatment of aminoglycoside-induced renal tubular cell injury. PMID:20649601

Spa47 is an oligomerization-activated type three secretion system (T3SS) ATPase from Shigella flexneri.

PubMed

Burgess, Jamie L; Jones, Heather B; Kumar, Prashant; Toth, Ronald T; Middaugh, C Russell; Antony, Edwin; Dickenson, Nicholas E

2016-05-01

Gram-negative pathogens often use conserved type three secretion systems (T3SS) for virulence. The Shigella type three secretion apparatus (T3SA) penetrates the host cell membrane and provides a unidirectional conduit for injection of effectors into host cells. The protein Spa47 localizes to the base of the apparatus and is speculated to be an ATPase that provides the energy for T3SA formation and secretion. Here, we developed an expression and purification protocol, producing active Spa47 and providing the first direct evidence that Spa47 is a bona fide ATPase. Additionally, size exclusion chromatography and analytical ultracentrifugation identified multiple oligomeric species of Spa47 with the largest greater than 8 fold more active for ATP hydrolysis than the monomer. An ATPase inactive Spa47 point mutant was then engineered by targeting a conserved Lysine within the predicted Walker A motif of Spa47. Interestingly, the mutant maintained a similar oligomerization pattern as active Spa47, but was unable to restore invasion phenotype when used to complement a spa47 null S. flexneri strain. Together, these results identify Spa47 as a Shigella T3SS ATPase and suggest that its activity is linked to oligomerization, perhaps as a regulatory mechanism as seen in some related pathogens. Additionally, Spa47 catalyzed ATP hydrolysis appears to be essential for host cell invasion, providing a strong platform for additional studies dissecting its role in virulence and providing an attractive target for anti-infective agents. © 2016 The Protein Society.

Secreted CLCA1 modulates TMEM16A to activate Ca(2+)-dependent chloride currents in human cells.

PubMed

Sala-Rabanal, Monica; Yurtsever, Zeynep; Nichols, Colin G; Brett, Tom J

2015-03-17

Calcium-activated chloride channel regulator 1 (CLCA1) activates calcium-dependent chloride currents; neither the target, nor mechanism, is known. We demonstrate that secreted CLCA1 activates calcium-dependent chloride currents in HEK293T cells in a paracrine fashion, and endogenous TMEM16A/Anoctamin1 conducts the currents. Exposure to exogenous CLCA1 increases cell surface levels of TMEM16A and cellular binding experiments indicate CLCA1 engages TMEM16A on the surface of these cells. Altogether, our data suggest that CLCA1 stabilizes TMEM16A on the cell surface, thus increasing surface expression, which results in increased calcium-dependent chloride currents. Our results identify the first Cl(-) channel target of the CLCA family of proteins and establish CLCA1 as the first secreted direct modifier of TMEM16A activity, delineating a unique mechanism to increase currents. These results suggest cooperative roles for CLCA and TMEM16 proteins in influencing the physiology of multiple tissues, and the pathology of multiple diseases, including asthma, COPD, cystic fibrosis, and certain cancers.

A role for the organic anion transporter OAT3 in renal creatinine secretion in mice

PubMed Central

Eraly, Satish A.; Rao, Satish Ramachandra; Gerasimova, Maria; Rose, Michael; Nagle, Megha; Anzai, Naohiko; Smith, Travis; Sharma, Kumar; Nigam, Sanjay K.; Rieg, Timo

2012-01-01

Tubular secretion of the organic cation, creatinine, limits its value as a marker of glomerular filtration rate (GFR) but the molecular determinants of this pathway are unclear. The organic anion transporters, OAT1 and OAT3, are expressed on the basolateral membrane of the proximal tubule and transport organic anions but also neutral compounds and cations. Here, we demonstrate specific uptake of creatinine into mouse mOat1- and mOat3-microinjected Xenopus laevis oocytes at a concentration of 10 μM (i.e., similar to physiological plasma levels), which was inhibited by both probenecid and cimetidine, prototypical competitive inhibitors of organic anion and cation transporters, respectively. Renal creatinine clearance was consistently greater than inulin clearance (as a measure of GFR) in wild-type (WT) mice but not in mice lacking OAT1 (Oat1−/−) and OAT3 (Oat3−/−). WT mice presented renal creatinine net secretion (0.23 ± 0.03 μg/min) which represented 45 ± 6% of total renal creatinine excretion. Mean values for renal creatinine net secretion and renal creatinine secretion fraction were not different from zero in Oat1−/− (−0.03 ± 0.10 μg/min; −3 ± 18%) and Oat3−/− (0.01 ± 0.06 μg/min; −6 ± 19%), with greater variability in Oat1−/−. Expression of OAT3 protein in the renal membranes of Oat1−/− mice was reduced to ∼6% of WT levels, and that of OAT1 in Oat3−/− mice to ∼60%, possibly as a consequence of the genes for Oat1 and Oat3 having adjacent chromosomal locations. Plasma creatinine concentrations of Oat3−/− were elevated in clearance studies under anesthesia but not following brief isoflurane anesthesia, indicating that the former condition enhanced the quantitative contribution of OAT3 for renal creatinine secretion. The results are consistent with a contribution of OAT3 and possibly OAT1 to renal creatinine secretion in mice. PMID:22338083

Bile salt receptor complex activates a pathogenic type III secretion system

DOE PAGES

Li, Peng; Rivera-Cancel, Giomar; Kinch, Lisa N.; ...

2016-07-05

Bile is an important component of the human gastrointestinal tract with an essential role in food absorption and antimicrobial activities. Enteric bacterial pathogens have developed strategies to sense bile as an environmental cue to regulate virulence genes during infection. We discovered that Vibrio parahaemolyticus VtrC, along with VtrA and VtrB, are required for activating the virulence type III secretion system 2 in response to bile salts. The VtrA/VtrC complex activates VtrB in the presence of bile salts. The crystal structure of the periplasmic domains of the VtrA/VtrC heterodimer reveals a β-barrel with a hydrophobic inner chamber. A co-crystal structure ofmore » VtrA/VtrC with bile salt, along with biophysical and mutational analysis, demonstrates that the hydrophobic chamber binds bile salts and activates the virulence network. As part of a family of conserved signaling receptors, VtrA/VtrC provides structural and functional insights into the evolutionarily conserved mechanism used by bacteria to sense their environment.« less

Small ubiquitin-related modifier is secreted and shows cytokine-like activity.

PubMed

Hosono, Hidetaka; Yokosawa, Hideyoshi

2008-05-01

Small ubiquitin-related modifier (SUMO) is a type I ubiquitin-like protein family member and is covalently attached to various target proteins. Through this post-translational modification, SUMO plays important roles in various cellular events. Here, we show that SUMO is secreted from cultured cells in an endoplasmic reticulum (ER)/Golgi-independent manner and that this secretion occurs without covalent binding to target proteins or chain formation. Overexpression experiments using C-terminally truncated mutants of SUMO revealed that the secretion requires the C-terminal sequence. Recombinant SUMO-3 protein was capable of binding to and promoting the proliferation of cultured cells. Thus, we propose that SUMO functions as a cytokine-like molecule extracellularly.

Mechanism of intracellular signal transduction during injury of renal tubular cells induced by postasphyxial serum in neonates with asphyxia.

PubMed

Zhao, Jin; Dong, Wen-Bin; Li, Peng-yun; Deng, Chun-liang

2009-01-01

Renal injury is a severe and extremely common complication that occurs early in neonates with asphyxia. Reperfusion injury has been suggested as the cause of kidney damage during resuscitation of neonatal asphyxia. Previous studies have demonstrated that postasphyxial serum from neonates with asphyxia may result in apoptosis of renal tubular cells. However, the mechanisms that mediate renal tubular cell apoptosis induced by postasphyxial serum remain poorly understood. In this report we investigate the intracellular signal transduction mechanisms that operate during injury of renal tubular cells induced by postasphyxial serum in neonates. Cultured human renal proximal tubular cells HK-2 cell were exposed to 10% fetal calf serum (normal control), 20% postasphyxial serum or 20% postasphyxial serum with pyrrolidine dithiocarbamate (PDTC). The expression of both BAD and BAX in the cytoplasm was detected by immunohistochemistry. The mitochondria membrane potential (Deltapsim) was examined by confocal microscopy, and the release of the apoptogenic mitochondrial proteins cytochrome C and AIF was assessed by Western blot analysis. Loss of mitochondria membrane potential was detected in HK-2 cells treated with 20% postasphyxial serum as compared to cells in normal serum or PTDC-pretreated cells in 20% postasphyxial serum. A significant increase of Bad and Bax protein expression was also detected, along with the release of cytochrome C and AIF from mitochondria to cytosol in the postasphyxial serum treated cells, but not in the normal or PTDC-pretreated control cells. Our findings suggest that postasphyxial serum may induce renal tubular cell apoptosis through the mitochondrial pathway, and its intracellular signal transduction mechanism includes the activation of nuclear factor-kappaB. Copyright 2009 S. Karger AG, Basel.

An intracellular matrix metalloproteinase-2 isoform induces tubular regulated necrosis: implications for acute kidney injury.

PubMed

Ceron, Carla S; Baligand, Celine; Joshi, Sunil; Wanga, Shaynah; Cowley, Patrick M; Walker, Joy P; Song, Sang Heon; Mahimkar, Rajeev; Baker, Anthony J; Raffai, Robert L; Wang, Zhen J; Lovett, David H

2017-06-01

Acute kidney injury (AKI) causes severe morbidity, mortality, and chronic kidney disease (CKD). Mortality is particularly marked in the elderly and with preexisting CKD. Oxidative stress is a common theme in models of AKI induced by ischemia-reperfusion (I-R) injury. We recently characterized an intracellular isoform of matrix metalloproteinase-2 (MMP-2) induced by oxidative stress-mediated activation of an alternate promoter in the first intron of the MMP-2 gene. This generates an NH 2 -terminal truncated MMP-2 (NTT-MMP-2) isoform that is intracellular and associated with mitochondria. The NTT-MMP-2 isoform is expressed in kidneys of 14-mo-old mice and in a mouse model of coronary atherosclerosis and heart failure with CKD. We recently determined that NTT-MMP-2 is induced in human renal transplants with delayed graft function and correlated with tubular cell necrosis. To determine mechanism(s) of action, we generated proximal tubule cell-specific NTT-MMP-2 transgenic mice. Although morphologically normal at the light microscopic level at 4 mo, ultrastructural studies revealed foci of tubular epithelial cell necrosis, the mitochondrial permeability transition, and mitophagy. To determine whether NTT-MMP-2 expression enhances sensitivity to I-R injury, we performed unilateral I-R to induce mild tubular injury in wild-type mice. In contrast, expression of the NTT-MMP-2 isoform resulted in a dramatic increase in tubular cell necrosis, inflammation, and fibrosis. NTT-MMP-2 mice had enhanced expression of innate immunity genes and release of danger-associated molecular pattern molecules. We conclude that NTT-MMP-2 "primes" the kidney to enhanced susceptibility to I-R injury via induction of mitochondrial dysfunction. NTT-MMP-2 may be a novel AKI treatment target.

DNA damage response in renal ischemia-reperfusion and ATP-depletion injury of renal tubular cells.

PubMed

Ma, Zhengwei; Wei, Qingqing; Dong, Guie; Huo, Yuqing; Dong, Zheng

2014-07-01

Renal ischemia-reperfusion leads to acute kidney injury (AKI) that is characterized pathologically by tubular damage and cell death, followed by tubular repair, atrophy and interstitial fibrosis. Recent work suggested the possible presence of DNA damage response (DDR) in AKI. However, the evidence is sketchy and the role and regulation of DDR in ischemic AKI remain elusive. In this study, we demonstrated the induction of phosphorylation of ATM, H2AX, Chk2 and p53 during renal ischemia-reperfusion in mice, suggesting DDR in kidney tissues. DDR was also induced in vitro during the recovery or "reperfusion" of renal proximal tubular cells (RPTCs) after ATP depletion. DDR in RPTCs was abrogated by supplying glucose to maintain ATP via glycolysis, indicating that the DDR depends on ATP depletion. The DDR was also suppressed by the general caspase inhibitor z-VAD and the overexpression of Bcl-2, supporting a role of apoptosis-associated DNA damage in the DDR. N-acetylcysteine (NAC), an antioxidant, suppressed the phosphorylation of ATM and p53 and, to a less extent, Chk2, but NAC increased the phosphorylation and nuclear foci formation of H2AX. Interestingly, NAC increased apoptosis, which may account for the observed H2AX activation. Ku55933, an ATM inhibitor, blocked ATM phosphorylation and ameliorated the phosphorylation of Chk2 and p53, but it increased H2AX phosphorylation and nuclear foci formation. Ku55933 also increased apoptosis in RPTCs following ATP depletion. The results suggest that DDR occurs during renal ischemia-reperfusion in vivo and ATP-depletion injury in vitro. The DDR is partially induced by apoptosis and oxidative stress-related DNA damage. ATM, as a sensor in the DDR, may play a cytoprotective role against tubular cell injury and death. Copyright © 2014 Elsevier B.V. All rights reserved.

DNA damage response in renal ischemia-reperfusion and ATP-depletion injury of renal tubular cells

PubMed Central

Ma, Zhengwei; Wei, Qingqing; Dong, Guie; Huo, Yuqing; Dong, Zheng

2014-01-01

Renal ischemia-reperfusion leads to acute kidney injury (AKI) that is characterized pathologically by tubular damage and cell death, followed by tubular repair, atrophy and interstitial fibrosis. Recent work suggested the possible presence of DNA damage response (DDR) in AKI. However, the evidence is sketchy and the role and regulation of DDR in ischemic AKI remain elusive. In this study, we demonstrated the induction of phosphorylation of ATM, H2AX, Chk2 and p53 during renal ischemia-reperfusion in mice, suggesting DDR in kidney tissues. DDR was also induced in vitro during the recovery or “reperfusion” of renal proximal tubular cells (RPTCs) after ATP-depletion. DDR in RPTCs was abrogated by supplying glucose to maintain ATP via glycolysis, indicating that the DDR depends on ATP depletion. The DDR was also suppressed by the general caspase inhibitor z-VAD and the overexpression of Bcl-2, supporting a role of apoptosis-associated DNA damage in the DDR. N-acetylcysteine (NAC), an antioxidant, suppressed the phosphorylation of ATM and p53 and, to a less extent, Chk2, but NAC increased the phosphorylation and nuclear foci formation of H2AX. Interestingly, NAC increased apoptosis, which may account for the observed H2AX activation. Ku55933, an ATM inhibitor, blocked ATM phosphorylation and ameliorated the phosphorylation of Chk2 and p53, but it increased H2AX phosphorylation and nuclear foci formation. Ku55933 also increased apoptosis in RPTCs following ATP-depletion. The results suggest that DDR occurs during renal ischemia-reperfusion in vivo and ATP-depletion injury in vitro. The DDR is partially induced by apoptosis and oxidative stress-related DNA damage. ATM, as a sensor in the DDR, may play a cytoprotective role against tubular cell injury and death. PMID:24726884

Evidence for an Intrinsic Renal Tubular Defect in Mice with Genetic Hypophosphatemic Rickets

PubMed Central

Cowgill, Larry D.; Goldfarb, Stanley; Lau, Kai; Slatopolsky, Eduardo; Agus, Zalman S.

1979-01-01

To investigate the role of parathyroid hormone (PTH) and(or) an intrinsic renal tubular reabsorptive defect for phosphate in mice with hereditary hypophosphatemic rickets, we performed clearance and micropuncture studies in hypophosphatemic mutants and nonaffected littermate controls. Increased fractional excretion of phosphate in mutants (47.2±4 vs. 30.8±2% in controls) was associated with reduced fractional and absolute reabsorption in the proximal convoluted tubule and more distal sites. Acute thyropara-thyroidectomy (TPTX) increased phosphate reabsorption in both mutants and controls with a fall in fractional phosphate excretion to ≅7.5% in both groups indicating that PTH modified the degree of phosphaturia in the intact mutants. Absolute reabsorption in the proximal tubule and beyond remained reduced in the mutants, however, possibly because of the reduced filtered load. Serum PTH levels were the same in intact mutants and normals as was renal cortical adenylate cyclase activity both before and after PTH stimulation. To evaluate the possibility that the phosphate wasting was caused by an intrinsic tubular defect that was masked by TPTX, glomerular fluid phosphate concentration was raised by phosphate infusion in TPTX mutants to levels approaching those of control mice. Phosphate excretion rose markedly and fractional reabsorption fell, but there was no change in absolute phosphate reabsorption in either the proximal tubule or beyond, indicating a persistent reabsorptive defect in the absence of PTH. We conclude that hereditary hypophosphatemia in the mouse is associated with a renal tubular defect in phosphate reabsorption, which is independent of PTH and therefore represents a specific intrinsic abnormality of phosphate transport. PMID:221535

In-Situ TEM-STM Observations of SWCNT Ropes/Tubular Transformations

NASA Technical Reports Server (NTRS)

Sola, F.; Lebron-Colon, M.; Ferreira, P. J.; Fonseca, L. F.; Meador, M. A.; Marin, C.

2010-01-01

Single-walled carbon nanotubes (SWCNTs) prepared by the HiPco process were purified using a modified gas phase purification technique. A TEM-STM holder was used to study the morphological changes of SWCNT ropes as a function of applied voltage. Kink formation, buckling behavior, tubular transformation and eventual breakdown of the system were observed. The tubular formation was attributed to a transformation from SWCNT ropes to multi-walled carbon nanotube (MWCNT) structures. It is likely mediated by the patching and tearing mechanism which is promoted primarily by the mobile vacancies generated due to current-induced heating and, to some extent, by electron irradiation.

Stem Cell Conditioned Culture Media Attenuated Albumin-Induced Epithelial– Mesenchymal Transition in Renal Tubular Cells

PubMed Central

Hu, Junping; Zhu, Qing; Li, Pin-Lan; Wang, Weili; Yi, Fan; Li, Ningjun

2015-01-01

Background Proteinuria-induced epithelial-mesenchymal transition (EMT) plays an important role in progressive renal tubulointerstitial fibrosis in chronic renal disease. Stem cell therapy has been used for different diseases. Stem cell conditioned culture media (SCM) exhibits similar beneficial effects as stem cell therapy. The present study tested the hypothesis that SCM inhibits albumin-induced EMT in cultured renal tubular cells. Methods Rat renal tubular cells were treated with/without albumin (20 μmg/ml) plus SCM or control cell media (CCM). EMT markers and inflammatory factors were measured by Western blot and fluorescent images. Results Albumin induced EMT as shown by significant decreases in levels of epithelial marker E-cadherin, increases in mesenchymal markers fibroblast-specific protein 1 and α-smooth muscle actin, and elevations in collagen I. SCM inhibited all these changes. Meanwhile, albumin induced NF-κB translocation from cytosol into nucleus and that SCM blocked the nuclear translocation of NF-κB. Albumin also increased the levels of pro-inflammatory factor monocyte chemoattractant protein-1 (MCP)-1 by nearly 30 fold compared with control. SCM almost abolished albumin-induced increase of MCP-1. Conclusion These results suggest that SCM attenuated albumin-induced EMT in renal tubular cells via inhibiting activation of inflammatory factors, which may serve as a new therapeutic approach for chronic kidney diseases. PMID:25832005

Method and apparatus for forming flues on tubular stock

DOEpatents

Beck, D.E.; Carson, C.

1979-12-21

The present invention is directed to a die mechanism utilized for forming flues on long, relatively narrow tubular stock. These flues are formed by displacing a die from within the tubular stock through perforations previously drilled through the tubular stock at selected locations. The drawing of the die upsets the material to form the flue of the desired configuration. The die is provided with a lubricating system which enables the lubricant to be dispensed uniformly about the entire periphery of the die in contact with the material being upset so as to assure the formation of the flues. Further, the lubricant is dispensed from within the die onto the peripheral surface of the latter at pressures in the range of about 2000 to 10,000 psi so as to assure the adequate lubrication of the die during the drawing operation. By injecting the lubricant at such high pressures, low viscosity liquid, such as water and/or alcohol, may be efficiently used as a lubricant and also provides a mechanism by which the lubricant may be evaporated from the surface of the flues at ambient conditions so as to negate the cleansing operations previously required prior to joining the flues to other conduit mechanisms by fusion welding and the like.

Durability and robustness of tubular molten carbonate fuel cells

NASA Astrophysics Data System (ADS)

Kawase, Makoto

2017-12-01

One anticipated system for high-efficiency power generation is the combination of syngas from gasification and high temperature fuel cells. The system uses a pressurization system, and it takes into account poisoning by impurities in the syngas. The durability and robustness of the fuel cells used in this system are an important issue for commercial applications. This study focuses on tubular molten carbonate fuel cells (MCFCs), which seem to be relatively durable compared with conventional planar-type MCFCs. Various power generation tests were performed in order to evaluate the durability and robustness of the tubular MCFCs. After continuous generation tests at 0.3 MPa, the cell voltage decay rate was found to be 0.8 mV/1000 h at 0.2 A/cm2. Moreover, it was found to be possible to generate power stably with fuel gas containing 20 ppm H2S. When the differential pressure between the anode and cathode was set to 0.1 MPa, the power generation tests were performed without gas leakage. In addition, starting (heating) and stopping (cooling) could be done in a short period, meaning that the cold start/stop characteristics are favorable. Therefore, the tubular MCFC was confirmed to have the durability necessary for a power generation system.

The Design and Performance Evaluation of Hydroformed Tubular Torsion Beam Axle

NASA Astrophysics Data System (ADS)

Kim, Jaehyun; Oh, Jinho; Choi, Hanho

2010-06-01

Suspensions for vehicles are structural devices used for suspending a vehicle body and absorbing shocks from the road. Thus, the suspensions must be designed such that they can attenuate shocks from a road and make passengers feel comfortable despite the shocks, and improve steering stability, determined by the ground contact force of tires during running of vehicles. Another important factor to be considered while designing suspensions is that the suspensions must maintain desired stiffness and desired durability despite the repeated application of shocks from roads thereto. The present relates, in general, to a tubular torsion beam for rear suspensions of vehicles and a manufacturing method thereof and, more particularly, to the provision of tubular torsion beams having excellent roll stiffness and excellent roll strength, produced through hydroforming. The hydroforming technology has a lot of benefit which is shape accuracy, good durability caused by compressive pressure, and good forming quality. In this study, the performance evaluation of the hydroformed tubular torsion beam axle is evaluated.

Regulation of Renin Secretion and Arterial Pressure During Prolonged Baroreflex Activation: Influence of Salt Intake

PubMed Central

Hildebrandt, Drew A.; Irwin, Eric D.; Cates, Adam W.; Lohmeier, Thomas E.

2014-01-01

Chronic electrical activation of the carotid baroreflex produces sustained reductions in sympathetic activity and arterial pressure and is currently being evaluated as antihypertensive therapy for patients with resistant hypertension. However, the influence of variations in salt intake on blood pressure lowering during baroreflex activation has not been determined. As sensitivity of arterial pressure to salt intake is linked to the responsiveness of renin secretion, we determined steady-state levels of arterial pressure and neurohormonal responses in 6 dogs on low, normal, and high salt intakes ( 5, 40, 450 mmol/day, respectively) under control conditions and during a 7-day constant level of baroreflex activation. Under control conditions, there was no difference in mean arterial pressure at low (92±1) and normal (92±2 mmHg) sodium intakes, but pressure increased 9 ±2 mmHg during high salt. Plasma renin activity (2.01±0.23, 0.93±0.20, 0.01±0.01 ng ANGI/mL/hr) and plasma aldosterone (10.3±1.9, 3.5±0.5, 1.7±0.1ng/dL) were inversely related to salt intake, whereas there were no changes in plasma norepinephrine. Although mean arterial pressure (19-22 mmHg) and norepinephrine (20-40%) were lower at all salt intakes during baroreflex activation, neither the changes in pressure nor the absolute values for plasma renin activity or aldosterone in response to salt were different from control conditions. These findings demonstrate that suppression of sympathetic activity by baroreflex activation lowers arterial pressure without increasing renin release and indicate that changes in sympathetic activity are not primary mediators of the effect of salt on renin secretion. Consequently, blood pressure lowering during baroreflex activation is independent of salt intake. PMID:24935941

Salivary Gland Secretion.

ERIC Educational Resources Information Center

Dorman, H. L.; And Others

1981-01-01

Describes materials and procedures for an experiment utilizing a live dog to demonstrate: (1) physiology of the salivary gland; (2) parasympathetic control of the salivary gland; (3) influence of varying salivary flow rates on sodium and potassium ions, osmolarity and pH; and (4) salivary secretion as an active process. (DS)

Pancreatic bicarbonate secretion involves two proton pumps.

PubMed

Novak, Ivana; Wang, Jing; Henriksen, Katrine L; Haanes, Kristian A; Krabbe, Simon; Nitschke, Roland; Hede, Susanne E

2011-01-07

Pancreas secretes fluid rich in digestive enzymes and bicarbonate. The alkaline secretion is important in buffering of acid chyme entering duodenum and for activation of enzymes. This secretion is formed in pancreatic ducts, and studies to date show that plasma membranes of duct epithelium express H(+)/HCO(3)(-) transporters, which depend on gradients created by the Na(+)/K(+)-ATPase. However, the model cannot fully account for high-bicarbonate concentrations, and other active transporters, i.e. pumps, have not been explored. Here we show that pancreatic ducts express functional gastric and non-gastric H(+)-K(+)-ATPases. We measured intracellular pH and secretion in small ducts isolated from rat pancreas and showed their sensitivity to H(+)-K(+) pump inhibitors and ion substitutions. Gastric and non-gastric H(+)-K(+) pumps were demonstrated on RNA and protein levels, and pumps were localized to the plasma membranes of pancreatic ducts. Quantitative analysis of H(+)/HCO(3)(-) and fluid transport shows that the H(+)-K(+) pumps can contribute to pancreatic secretion in several species. Our results call for revision of the bicarbonate transport physiology in pancreas, and most likely other epithelia. Furthermore, because pancreatic ducts play a central role in several pancreatic diseases, it is of high relevance to understand the role of H(+)-K(+) pumps in pathophysiology.

Distinct activities of Bartonella henselae type IV secretion effector proteins modulate capillary-like sprout formation.

PubMed

Scheidegger, F; Ellner, Y; Guye, P; Rhomberg, T A; Weber, H; Augustin, H G; Dehio, C

2009-07-01

The zoonotic pathogen Bartonella henselae (Bh) can lead to vasoproliferative tumour lesions in the skin and inner organs known as bacillary angiomatosis and bacillary peliosis. The knowledge on the molecular and cellular mechanisms involved in this pathogen-triggered angiogenic process is confined by the lack of a suitable animal model and a physiologically relevant cell culture model of angiogenesis. Here we employed a three-dimensional in vitro angiogenesis assay of collagen gel-embedded endothelial cell (EC) spheroids to study the angiogenic properties of Bh. Spheroids generated from Bh-infected ECs displayed a high capacity to form sprouts, which represent capillary-like projections into the collagen gel. The VirB/VirD4 type IV secretion system and a subset of its translocated Bartonella effector proteins (Beps) were found to profoundly modulate this Bh-induced sprouting activity. BepA, known to protect ECs from apoptosis, strongly promoted sprout formation. In contrast, BepG, triggering cytoskeletal rearrangements, potently inhibited sprouting. Hence, the here established in vitro model of Bartonella- induced angiogenesis revealed distinct and opposing activities of type IV secretion system effector proteins, which together with a VirB/VirD4-independent effect may control the angiogenic activity of Bh during chronic infection of the vasculature.

Activation of FoxM1 Revitalizes the Replicative Potential of Aged β-Cells in Male Mice and Enhances Insulin Secretion

PubMed Central

Golson, Maria L.; Dunn, Jennifer C.; Maulis, Matthew F.; Dadi, Prasanna K.; Osipovich, Anna B.; Magnuson, Mark A.; Jacobson, David A.

2015-01-01

Type 2 diabetes incidence increases with age, while β-cell replication declines. The transcription factor FoxM1 is required for β-cell replication in various situations, and its expression declines with age. We hypothesized that increased FoxM1 activity in aged β-cells would rejuvenate proliferation. Induction of an activated form of FoxM1 was sufficient to increase β-cell mass and proliferation in 12-month-old male mice after just 2 weeks. Unexpectedly, at 2 months of age, induction of activated FoxM1 in male mice improved glucose homeostasis with unchanged β-cell mass. Cells expressing activated FoxM1 demonstrated enhanced glucose-stimulated Ca2+ influx, which resulted in improved glucose tolerance through enhanced β-cell function. Conversely, our laboratory has previously demonstrated that mice lacking FoxM1 in the pancreas display glucose intolerance or diabetes with only a 60% reduction in β-cell mass, suggesting that the loss of FoxM1 is detrimental to β-cell function. Ex vivo insulin secretion was therefore examined in size-matched islets from young mice lacking FoxM1 in β-cells. Foxm1-deficient islets indeed displayed reduced insulin secretion. Our studies reveal that activated FoxM1 increases β-cell replication while simultaneously enhancing insulin secretion and improving glucose homeostasis, making FoxM1 an attractive therapeutic target for diabetes. PMID:26251404

A technical case report on use of tubular retractors for anterior cervical spine surgery.

PubMed

Kulkarni, Arvind G; Patel, Ankit; Ankith, N V

2017-12-19

The authors put-forth this technical report to establish the feasibility of performing an anterior cervical corpectomy and fusion (ACCF) and a two-level anterior cervical discectomy and fusion (ACDF) using a minimally invasive approach with tubular retractors. First case: cervical spondylotic myelopathy secondary to a large postero-inferiorly migrated disc treated with corpectomy and reconstruction with a mesh cage and locking plate. Second case: cervical disc herniation with radiculopathy treated with a two-level ACDF. Both cases were operated with minimally invasive approach with tubular retractor using a single incision. Technical aspects and clinical outcomes have been reported. No intra or post-operative complications were encountered. Intra-operative blood loss was negligible. The patients had a cosmetic scar on healing. Standard procedure of placement of tubular retractors is sufficient for adequate surgical exposure with minimal invasiveness. Minimally invasive approach to anterior cervical spine with tubular retractors is feasible. This is the first report on use of minimally invasive approach for ACCF and two-level ACDF.

Facile Fabrication of Uniform Polyaniline Nanotubes with Tubular Aluminosilicates as Templates

NASA Astrophysics Data System (ADS)

Zhang, Long; Liu, Peng

2008-08-01

The uniform polyaniline (PANI) nanotubes, with inner diameter, outer diameter, and tubular thickness of 40, 60, and 10 nm, respectively, were prepared successfully by using natural tubular aluminosilicates as templates. The halloysite nanotubes were coated with PANI via the in situ chemical oxidation polymerization. Then the templates were etched with HCl/HF solution. The PANI nanotubes were characterized using FTIR, X-ray diffraction, and transmission electron microscopy. The conductivity of the PANI nanotubes was found to be 1.752 × 10-5 (Ω·cm)-1.

4-Phenylbutyric acid reduces endoplasmic reticulum stress, trypsin activation, and acinar cell apoptosis while increasing secretion in rat pancreatic acini.

PubMed

Malo, Antje; Krüger, Burkhard; Göke, Burkhard; Kubisch, Constanze H

2013-01-01

Endoplasmic reticulum (ER) stress leads to misfolded proteins inside the ER and initiates unfolded protein response (UPR). Unfolded protein response components are involved in pancreatic function and activated during pancreatitis. However, the exact role of ER stress in the exocrine pancreas is unclear. The present study examined the effects of 4-phenylbutyric acid (4-PBA), an ER chaperone, on acini and UPR components. Rat acini were stimulated with cholecystokinin (10 pmol/L to 10 nmol/L) with or without preincubation of 4-PBA. The UPR components were analyzed, including chaperone-binding protein, protein kinaselike ER kinase, X-box-binding protein 1, c-Jun NH(2)-terminal kinase, CCAAT/enhancer-binding protein homologous protein, caspase 3, and apoptosis. Effects of 4-PBA were measured on secretion, calcium, and trypsin activation. 4-Phenylbutyric acid led to an increase of secretion, whereas trypsin activation with supraphysiological cholecystokinin was significantly reduced. 4-Phenylbutyric acid prevented chaperone-binding protein up-regulation, diminished protein kinaselike ER kinase, and c-Jun NH2-terminal kinase phosphorylation, prohibited X-box-binding protein 1 splicing and CCAAT/enhancer-binding protein homologous protein expression, caspase 3 activation, and apoptosis caused by supraphysiological cholecystokinin. By incubation with 4-PBA, beneficial in urea cycle deficiency, it was possible to enhance enzyme secretion to suppress trypsin activation, UPR activation, and proapoptotic pathways. The data hint new perspectives for the use of chemical chaperones in pancreatic diseases.

Stretch induced endothelin-1 secretion by adult rat astrocytes involves calcium influx via stretch-activated ion channels (SACs)

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

Ostrow, Lyle W., E-mail: lostrow1@jhmi.edu; Suchyna, Thomas M.; Sachs, Frederick

2011-06-24

Highlights: {yields} Endothelin-1 expression by adult rat astrocytes correlates with cell proliferation. {yields} Stretch-induced ET-1 is inhibited by GsMtx-4, a specific inhibitor of Ca{sup 2+} permeant SACs. {yields} The less specific SAC inhibitor streptomycin also inhibits ET-1 secretion. {yields} Stretch-induced ET-1 production depends on a calcium influx. {yields} SAC pharmacology may provide a new class of therapeutic agents for CNS pathology. -- Abstract: The expression of endothelins (ETs) and ET-receptors is often upregulated in brain pathology. ET-1, a potent vasoconstrictor, also inhibits the expression of astrocyte glutamate transporters and is mitogenic for astrocytes, glioma cells, neurons, and brain capillary endothelia.more » We have previously shown that mechanical stress stimulates ET-1 production by adult rat astrocytes. We now show in adult astrocytes that ET-1 production is driven by calcium influx through stretch-activated ion channels (SACs) and the ET-1 production correlates with cell proliferation. Mechanical stimulation using biaxial stretch (<20%) of a rubber substrate increased ET-1 secretion, and 4 {mu}M GsMTx-4 (a specific inhibitor of SACs) inhibited secretion by 30%. GsMTx-4 did not alter basal ET-1 levels in the absence of stretch. Decreasing the calcium influx by lowering extracellular calcium also inhibited stretch-induced ET-1 secretion without effecting ET-1 secretion in unstretched controls. Furthermore, inhibiting SACs with the less specific inhibitor streptomycin also inhibited stretch-induced ET-1 secretion. The data can be explained with a simple model in which ET-1 secretion depends on an internal Ca{sup 2+} threshold. This coupling of mechanical stress to the astrocyte endothelin system through SACs has treatment implications, since all pathology deforms the surrounding parenchyma.« less

Elastomer liners for geothermal tubulars Y267 EPDM Liner Program:

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

Hirasuna, A.R.; Davis, D.L.; Flickinger, J.E.

1987-12-01

The elastomer, Y267 EPDM, has been identified as a hydrothermally stable material which can operate at temperatures in excess of 320/sup 0/C. The goal of the Y267 Liner Program was to demonstrate the feasibility of using this material as a liner for mild steel tubulars to prevent or mitigate corrosion. If successful, the usage of EPDM lined pipe by the geothermal community may have a significant impact on operating costs and serve as a viable alternative to the use of alloyed tubulars. Tooling procedures were developed under this program to mold a 0.64 cm (0.25'') thick Y267 EPDM liner intomore » a tubular test section 61 cm (2') in length and 19.1 cm (7.5'') in diameter (ID). A successful effort was made to identify a potential coupling agent to be used to bond the elastomer to the steel tubular wall. This agent was found to withstand the processing conditions associated with curing the elastomer at 288/sup 0/C and to retain a significant level of adhesive strength following hydrothermal testing in a synthetic brine at 260/sup 0/C for a period of 166 hours. Bonding tests were conducted on specimens of mild carbon steel and several alloys including Hastelloy C-276. An objective of the program was to field test the lined section of pipe mentioned above at a geothermal facility in the Imperial Valley. Though a test was conducted, problems encountered during the lining operation precluded an encouraging outcome. The results of the field demonstration were inconclusive. 6 refs., 13 figs., 13 tabs« less

Filament winding technique, experiment and simulation analysis on tubular structure

NASA Astrophysics Data System (ADS)

Quanjin, Ma; Rejab, M. R. M.; Kaige, Jiang; Idris, M. S.; Harith, M. N.

2018-04-01

Filament winding process has emerged as one of the potential composite fabrication processes with lower costs. Filament wound products involve classic axisymmetric parts (pipes, rings, driveshafts, high-pressure vessels and storage tanks), non-axisymmetric parts (prismatic nonround sections and pipe fittings). Based on the 3-axis filament winding machine has been designed with the inexpensive control system, it is completely necessary to make a relative comparison between experiment and simulation on tubular structure. In this technical paper, the aim of this paper is to perform a dry winding experiment using the 3-axis filament winding machine and simulate winding process on the tubular structure using CADWIND software with 30°, 45°, 60° winding angle. The main result indicates that the 3-axis filament winding machine can produce tubular structure with high winding pattern performance with different winding angle. This developed 3-axis winding machine still has weakness compared to CAWIND software simulation results with high axes winding machine about winding pattern, turnaround impact, process error, thickness, friction impact etc. In conclusion, the 3-axis filament winding machine improvements and recommendations come up with its comparison results, which can intuitively understand its limitations and characteristics.

Integrated continuous dissolution, refolding and tag removal of fusion proteins from inclusion bodies in a tubular reactor.

PubMed

Pan, Siqi; Zelger, Monika; Jungbauer, Alois; Hahn, Rainer

2014-09-20

An integrated continuous tubular reactor system was developed for processing an autoprotease expressed as inclusion bodies. The inclusion bodies were suspended and fed into the tubular reactor system for continuous dissolving, refolding and precipitation. During refolding, the dissolved autoprotease cleaves itself, separating the fusion tag from the target peptide. Subsequently, the cleaved fusion tag and any uncleaved autoprotease were precipitated out in the precipitation step. The processed exiting solution results in the purified soluble target peptide. Refolding and precipitation yields performed in the tubular reactor were similar to batch reactor and process was stable for at least 20 h. The authenticity of purified peptide was also verified by mass spectroscopy. Productivity (in mg/l/h and mg/h) calculated in the tubular process was twice and 1.5 times of the batch process, respectively. Although it is more complex to setup a tubular than a batch reactor, it offers faster mixing, higher productivity and better integration to other bioprocessing steps. With increasing interest of integrated continuous biomanufacturing, the use of tubular reactors in industrial settings offers clear advantages. Copyright © 2014 Elsevier B.V. All rights reserved.

Regulation of aldosterone secretion by mineralocorticoid receptor-mediated signaling.

PubMed

Chong, Cherish; Hamid, Anis; Yao, Tham; Garza, Amanda E; Pojoga, Luminita H; Adler, Gail K; Romero, Jose R; Williams, Gordon H

2017-03-01

We posit the existence of a paracrine/autocrine negative feedback loop, mediated by the mineralocorticoid receptor (MR), regulating aldosterone secretion. To assess this hypothesis, we asked whether altering MR activity in zona glomerulosa (ZG) cells affects aldosterone production. To this end, we studied ex vivo ZG cells isolated from male Wistar rats fed chow containing either high (1.6% Na + (HS)) or low (0.03% Na + (LS)) amount of sodium. Western blot analyses demonstrated that MR was present in both the ZG and zona fasciculata/zona reticularis (ZF/ZR/ZR). In ZG cells isolated from rats on LS chow, MR activation by fludrocortisone produced a 20% and 60% reduction in aldosterone secretion basally and in response to angiotensin II (ANGII) stimulation, respectively. Corticosterone secretion was increased in these cells suggesting that aldosterone synthase activity was being reduced by fludrocortisone. In contrast, canrenoic acid, an MR antagonist, enhanced aldosterone production by up to 30% both basally and in response to ANGII. Similar responses were observed in ZG cells from rats fed HS. Modulating glucocorticoid receptor (GR) activity did not alter aldosterone production by ZG cells; however, altering GR activity did modify corticosterone production from ZF/ZR/ZR cells both basally and in response to adrenocorticotropic hormone (ACTH). Additionally, activating the MR in ZF/ZR/ZR cells strikingly reduced corticosterone secretion. In summary, these data support the hypothesis that negative ultra-short feedback loops regulate adrenal steroidogenesis. In the ZG, aldosterone secretion is regulated by the MR, but not the GR, an effect that appears to be secondary to a change in aldosterone synthase activity. © 2017 Society for Endocrinology.

78 FR 56865 - Certain Oil Country Tubular Goods From India and Turkey: Postponement of Preliminary...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-16

... Country Tubular Goods From India and Turkey: Postponement of Preliminary Determination in the... (202) 482-0189 (Turkey), AD/CVD Operations, Import Administration, International Trade Administration... the countervailing duty investigations of certain oil country tubular goods from India and Turkey.\\1...

Facile Fabrication of Uniform Polyaniline Nanotubes with Tubular Aluminosilicates as Templates

PubMed Central

2008-01-01

The uniform polyaniline (PANI) nanotubes, with inner diameter, outer diameter, and tubular thickness of 40, 60, and 10 nm, respectively, were prepared successfully by using natural tubular aluminosilicates as templates. The halloysite nanotubes were coated with PANI via the in situ chemical oxidation polymerization. Then the templates were etched with HCl/HF solution. The PANI nanotubes were characterized using FTIR, X-ray diffraction, and transmission electron microscopy. The conductivity of the PANI nanotubes was found to be 1.752 × 10−5(Ω·cm)−1.

A Role for Tubular Necroptosis in Cisplatin-Induced AKI

PubMed Central

Xu, Yanfang; Ma, Huabin; Shao, Jing; Wu, Jianfeng; Zhou, Linying; Zhang, Zhirong; Wang, Yuze; Huang, Zhe; Ren, Junming; Liu, Suhuan; Chen, Xiangmei

2015-01-01

Cell death and inflammation in the proximal tubules are the hallmarks of cisplatin-induced AKI, but the mechanisms underlying these effects have not been fully elucidated. Here, we investigated whether necroptosis, a type of programmed necrosis, has a role in cisplatin-induced AKI. We found that inhibition of any of the core components of the necroptotic pathway—receptor-interacting protein 1 (RIP1), RIP3, or mixed lineage kinase domain-like protein (MLKL)—by gene knockout or a chemical inhibitor diminished cisplatin-induced proximal tubule damage in mice. Similar results were obtained in cultured proximal tubular cells. Furthermore, necroptosis of cultured cells could be induced by cisplatin or by a combination of cytokines (TNF-α, TNF-related weak inducer of apoptosis, and IFN-γ) that were upregulated in proximal tubules of cisplatin-treated mice. However, cisplatin induced an increase in RIP1 and RIP3 expression in cultured tubular cells in the absence of cytokine release. Correspondingly, overexpression of RIP1 or RIP3 enhanced cisplatin-induced necroptosis in vitro. Notably, inflammatory cytokine upregulation in cisplatin-treated mice was partially diminished in RIP3- or MLKL-deficient mice, suggesting a positive feedback loop involving these genes and inflammatory cytokines that promotes necroptosis progression. Thus, our data demonstrate that necroptosis is a major mechanism of proximal tubular cell death in cisplatin-induced nephrotoxic AKI. PMID:25788533

Status report on the development of a tubular electron beam ion source

NASA Astrophysics Data System (ADS)

Donets, E. D.; Donets, E. E.; Becker, R.; Liljeby, L.; Rensfelt, K.-G.; Beebe, E. N.; Pikin, A. I.

2004-05-01

The theoretical estimations and numerical simulations of tubular electron beams in both beam and reflex mode of source operation as well as the off-axis ion extraction from a tubular electron beam ion source (TEBIS) are presented. Numerical simulations have been done with the use of the IGUN and OPERA-3D codes. Numerical simulations with IGUN code show that the effective electron current can reach more than 100 A with a beam current density of about 300-400 A/cm2 and the electron energy in the region of several KeV with a corresponding increase of the ion output. Off-axis ion extraction from the TEBIS, being the nonaxially symmetric problem, was simulated with OPERA-3D (SCALA) code. The conceptual design and main parameters of new tubular sources which are under consideration at JINR, MSL, and BNL are based on these simulations.

Physical activity, sedentary behaviors, and estimated insulin sensitivity and secretion in pregnant and non-pregnant women

PubMed Central

2011-01-01

Background Overweight and obesity during pregnancy raise the risk of gestational diabetes and birth complications. Lifestyle factors like physical activity may decrease these risks through beneficial effects on glucose homeostasis. Here we examined physical activity patterns and their relationships with measures of glucose homeostasis in late pregnancy compared to non-pregnant women. Methods Normal weight and overweight women without diabetes (N = 108; aged 25-35 years) were studied; 35 were pregnant (in gestational weeks 28-32) and 73 were non-pregnant. Insulin sensitivity and β-cell response were estimated from an oral glucose tolerance test. Physical activity was measured during 10-days of free-living using a combined heart rate sensor and accelerometer. Total (TEE), resting (REE), and physical activity (PAEE) energy expenditure were measured using doubly-labeled water and expired gas indirect calorimetry. Results Total activity was associated with reduced first-phase insulin response in both pregnant (Regression r2 = 0.11; Spearman r = -0.47; p = 0.007) and non-pregnant women (Regression r2 = 0.11 Spearman; r = -0.36; p = 0.002). Relative to non-pregnant women, pregnant women were estimated to have secreted 67% more insulin and had 10% lower fasting glucose than non-pregnant women. Pregnant women spent 13% more time sedentary, 71% less time in moderate-to-vigorous intensity activity, had 44% lower objectively measured total activity, and 12% lower PAEE than non-pregnant women. Correlations did not differ significantly for any comparison between physical activity subcomponents and measures of insulin sensitivity or secretion. Conclusions Our findings suggest that physical activity conveys similar benefits on glucose homeostasis in pregnant and non-pregnant women, despite differences in subcomponents of physical activity. PMID:21679399

Cinnamic acid exerts anti-diabetic activity by improving glucose tolerance in vivo and by stimulating insulin secretion in vitro.

PubMed

Hafizur, Rahman M; Hameed, Abdul; Shukrana, Mishkat; Raza, Sayed Ali; Chishti, Sidra; Kabir, Nurul; Siddiqui, Rehan A

2015-02-15

Although the anti-diabetic activity of cinnamic acid, a pure compound from cinnamon, has been reported but its mechanism(s) is not yet clear. The present study was designed to explore the possible mechanism(s) of anti-diabetic activity of cinnamic acid in in vitro and in vivo non-obese type 2 diabetic rats. Non-obese type 2 diabetes was developed by injecting 90 mg/kg streptozotocin in 2-day-old Wistar pups. Cinnamic acid and cinnamaldehyde were administered orally to diabetic rats for assessing acute blood glucose lowering effect and improvement of glucose tolerance. Additionally, insulin secretory activity of cinnamic acid and cinnamaldehyde was evaluated in isolated mice islets. Cinnamic acid, but not cinnamaldehyde, decreased blood glucose levels in diabetic rats in a time- and dose-dependent manner. Oral administration of cinnamic acid with 5 and 10 mg/kg doses to diabetic rats improved glucose tolerance in a dose-dependent manner. The improvement by 10 mg/kg cinnamic acid was comparable to that of standard drug glibenclamide (5 mg/kg). Further in vitro studies showed that cinnamaldehyde has little or no effect on glucose-stimulated insulin secretion; however, cinnamic acid significantly enhanced glucose-stimulated insulin secretion in isolated islets. In conclusion, it can be said that cinnamic acid exerts anti-diabetic activity by improving glucose tolerance in vivo and stimulating insulin secretion in vitro. Copyright © 2015 Elsevier GmbH. All rights reserved.

Lipase Activity in Insect Oral Secretions Mediates Defense Responses in Arabidopsis1[C][W][OA

PubMed Central

Schäfer, Martin; Fischer, Christine; Meldau, Stefan; Seebald, Eileen; Oelmüller, Ralf; Baldwin, Ian T.

2011-01-01

How plants perceive herbivory is not yet well understood. We investigated early responses of the model plant Arabidopsis (Arabidopsis thaliana) to attack from the generalist grasshopper herbivore, Schistocerca gregaria (Caelifera). When compared with wounding alone, S. gregaria attack and the application of grasshopper oral secretions (GS) to puncture wounds elicited a rapid accumulation of various oxylipins, including 13-hydroperoxy octadecatrienoic acid, 12-oxo-phytodienoic acid (OPDA), jasmonic acid, and jasmonic acid-isoleucine. Additionally, GS increased cytosolic calcium levels, mitogen-activated protein kinase (MPK3 and MPK6) activity, and ethylene emission but not the accumulation of hydrogen peroxide. Although GS contain caeliferin A16:0, a putative elicitor of caeliferan herbivores, treatment with pure, synthetic caeliferin A16:0 did not induce any of the observed responses. With mutant plants, we demonstrate that the observed changes in oxylipin levels are independent of MPK3 and MPK6 activity but that MPK6 is important for the GS-induced ethylene release. Biochemical and pharmacological analyses revealed that the lipase activity of GS plays a central role in the GS-induced accumulation of oxylipins, especially OPDA, which could be fully mimicked by treating puncture wounds only with a lipase from Rhizopus arrhizus. GS elicitation increased the levels of OPDA-responsive transcripts. Because the oral secretions of most insects used to study herbivory-induced responses in Arabidopsis rapidly elicit similar accumulations of OPDA, we suggest that lipids containing OPDA (arabidopsides) play an important role in the activation of herbivory-induced responses. PMID:21546453

[Acute renal failure and proximal renal tubular dysfuntion in a patient with acquired immunodeficiency syndrome treated with tenofovir].

PubMed

de la Prada, F J; Prados, A M; Tugores, A; Uriol, M; Saus, C; Morey, A

2006-01-01

Tenofovir, a new nucleotide reverse transcriptase inhibitor that has good antiviral activity against drug-resistant strains of HIV, is structurally similar to cidofovir and adefovir and seems to be less nephrotoxic. Nephrotoxicity of cidofovir and adefovir is well established and they have been associated with increase for acute renal insufficiency due to tubular toxicity, possibly induced via mitochondrial deplection. Tenofovir has little mithocondrial toxicity in in vitro assays and early clinical studies. However some cases of renal tubular dysfuntion and renal failure related to tenofovir treatment have been published recently. Increased plasma concentrations of didanosine were observed after the adition of tenofovir and protease inhibitors can interact with the renal transport of organic anions leading to proximal tubular intracellular accumulation of tenofovir, yield Fanconi syndrome-type tubulopathy. We present a case in wich acute renal failure and proximal tubular dysfunction developed after therapy with tenofovir in a patiente with HIV who had suffered from complications of didanosine treatment. Although nephrotoxicity certainly occurs much less frequently with tenofovir that it does with other nuclotide analogues, use of tenofovir by patients with underlying renal disfuntion, for longer durations and/or associated with didanosine or lopinavir-ritonavir, might be associated with renal toxicity. Patients receiving tenofovir must be monitored for sings of tubulopathy with simple tests such us glycosuria, phosphaturia, proteinuria, phosphoremia and renal function, as well as assessment for signs of mithocondrial toxicity when a nucleoside analogue is being administered, and therapy should be stopped to avoid the risk of definitive renal failure.

Naturally occurring and stress induced tubular structures from mammalian cells, a survival mechanism

PubMed Central

Wu, Yonnie; Laughlin, Richard C; Henry, David C; Krueger, Darryl E; Hudson, JoAn S; Kuan, Cheng-Yi; He, Jian; Reppert, Jason; Tomkins, Jeffrey P

2007-01-01

Background Tubular shaped mammalian cells in response to dehydration have not been previously reported. This may be due to the invisibility of these cells in aqueous solution, and because sugars and salts added to the cell culture for manipulation of the osmotic conditions inhibit transformation of normal cells into tubular shaped structures. Results We report the transformation of normal spherical mammalian cells into tubular shaped structures in response to stress. We have termed these transformed structures 'straw cells' which we have associated with a variety of human tissue types, including fresh, post mortem and frozen lung, liver, skin, and heart. We have also documented the presence of straw cells in bovine brain and prostate tissues of mice. The number of straw cells in heart, lung tissues, and collapsed straw cells in urine increases with the age of the mammal. Straw cells were also reproduced in vitro from human cancer cells (THP1, CACO2, and MCF7) and mouse stem cells (D1 and adipose D1) by dehydrating cultured cells. The tubular center of the straw cells is much smaller than the original cell; houses condensed organelles and have filamentous extensions that are covered with microscopic hair-like structures and circular openings. When rehydrated, the filaments uptake water rapidly. The straw cell walls, have a range of 120 nm to 200 nm and are composed of sulfated-glucose polymers and glycosylated acidic proteins. The transformation from normal cell to straw cells takes 5 to 8 hr in open-air. This process is characterized by an increase in metabolic activity. When rehydrated, the straw cells regain their normal spherical shape and begin to divide in 10 to 15 days. Like various types of microbial spores, straw cells are resistant to harsh environmental conditions such as UV-C radiation. Conclusion Straw cells are specialized cellular structures and not artifacts from spontaneous polymerization, which are generated in response to stress conditions, like

Endocytosis of wheat germ agglutinin binding sites from the cell surface into a tubular endosomal network.

PubMed

Raub, T J; Koroly, M J; Roberts, R M

1990-04-01

By using fluorescence and electron microscopy, the endocytic pathway encountered by cell surface components after they had bound wheat germ agglutinin (WGA) was visualized. The majority of these components are thought to consist of sialylated glycoproteins (HMWAG) that represent a subpopulation of the total cell surface proteins but most of the externally disposed plasma membrane proteins of the cell. Examination of semi-thin sections by medium- and high-voltage electron microscopy revealed the three-dimensional organization of vesicular and tubular endosomes. Binding of either fluorescein isothiocyanate-, horseradish peroxidase-, or ferritin-conjugated WGA to cells at 4 degrees C showed that the HMWAG were distributed uniformly over the cell surface. Warming of surface-labeled cells to 37 degrees C resulted in the endocytosis of WGA into peripheral endosomes via invagination of regions of both coated and uncoated membrane. The peripheral endosome appeared as isolated complexes comprising a vesicular element (300-400 nm diam.) surrounded by and continuous with tubular cisternae (45-60 nm diam.), which did not interconnect the endosomes. After 30 min or more label also became localized in a network of anastomosing tubules (45-60 nm diam.) that were located in the centrosomal region of the cell. Endocytosed WGA-HMWAG complexes did not become associated with cisternae of the Golgi apparatus, although tubular and vesicular endosomes were noted in the vicinity of the trans-Golgi region. The accumulation of WGA-HMWAG in the endosomes within the centrosomal region was inhibited when cells were incubated at 18 degrees C. None of these compartments contained acid phosphatase activity, a result that is consistent with other data that the HMWAG do not pass through lysosomes initially. The kinetics of labeling were consistent with the interpretation that recycling of most of the WGA binding surface glycoproteins occurred rapidly from early peripheral endosomes followed by the

Furosemide/Fludrocortisone Test and Clinical Parameters to Diagnose Incomplete Distal Renal Tubular Acidosis in Kidney Stone Formers.

PubMed

Dhayat, Nasser A; Gradwell, Michael W; Pathare, Ganesh; Anderegg, Manuel; Schneider, Lisa; Luethi, David; Mattmann, Cedric; Moe, Orson W; Vogt, Bruno; Fuster, Daniel G

2017-09-07

Incomplete distal renal tubular acidosis is a well known cause of calcareous nephrolithiasis but the prevalence is unknown, mostly due to lack of accepted diagnostic tests and criteria. The ammonium chloride test is considered as gold standard for the diagnosis of incomplete distal renal tubular acidosis, but the furosemide/fludrocortisone test was recently proposed as an alternative. Because of the lack of rigorous comparative studies, the validity of the furosemide/fludrocortisone test in stone formers remains unknown. In addition, the performance of conventional, nonprovocative parameters in predicting incomplete distal renal tubular acidosis has not been studied. We conducted a prospective study in an unselected cohort of 170 stone formers that underwent sequential ammonium chloride and furosemide/fludrocortisone testing. Using the ammonium chloride test as gold standard, the prevalence of incomplete distal renal tubular acidosis was 8%. Sensitivity and specificity of the furosemide/fludrocortisone test were 77% and 85%, respectively, yielding a positive predictive value of 30% and a negative predictive value of 98%. Testing of several nonprovocative clinical parameters in the prediction of incomplete distal renal tubular acidosis revealed fasting morning urinary pH and plasma potassium as the most discriminative parameters. The combination of a fasting morning urinary threshold pH <5.3 with a plasma potassium threshold >3.8 mEq/L yielded a negative predictive value of 98% with a sensitivity of 85% and a specificity of 77% for the diagnosis of incomplete distal renal tubular acidosis. The furosemide/fludrocortisone test can be used for incomplete distal renal tubular acidosis screening in stone formers, but an abnormal furosemide/fludrocortisone test result needs confirmation by ammonium chloride testing. Our data furthermore indicate that incomplete distal renal tubular acidosis can reliably be excluded in stone formers by use of nonprovocative clinical

Effect of erythropoietin on mesenchymal stem cell differentiation and secretion in vitro in an acute kidney injury microenvironment.

PubMed

Liu, N M; Tian, J; Wang, W W; Han, G F; Cheng, J; Huang, J; Zhang, J Y

2013-02-28

We investigated the effect of erythropoietin (EPO) on differentiation and secretion of bone marrow-derived mesenchymal stem cells in an acute kidney injury microenvironment. Acute kidney injury mouse models were prepared. Both renal cortices were then immediately collected to produce the ischemia/reperfusion kidney homogenate supernatant. The morphological and ultrastructural changes in the cells were observed using an inverted microscope and a transmission electron microscope. Cytokeratin-18 was detected using flow cytometry. Bone morphogenetic protein-7 levels, hepatocyte growth factor, and vascular endothelial growth factor in the culture medium were detected using an enzyme-linked immunosorbent assay. The cells had high CD29 and CD44 expression, as well as low CD34 and CD45 expression. More round and oval cells with cobble-like appearances were observed after EPO treatment. In addition, an increase in the number of rough endoplasmic reticula, lysosomes, and mitochondria was observed in the cytoplasm; the intercellular junction peculiar to epithelial cells was also seen on the cell surface. After treatment with ischemia/reperfusion kidney homogenate supernatant, cytokeratin-18 expression increased significantly and EPO could magnify its expression. Bone morphogenetic protein-7 levels, hepatocyte growth factor, and vascular endothelial growth factor levels after treatment with ischemia/reperfusion kidney homogenate supernatant significantly decreased, whereas EPO increased the cytokine secretion. The acute kidney injury microenvironment can induce the bone marrow-derived mesenchymal stem cells to partially differentiate into renal tubular epithelium-shaped cells, but weaken their secretion function. EPO intervention can boost up their differentiation function and reverse their low secretion effect.

Adrenal androgen secretion and dopaminergic activity in anorexia nervosa.

PubMed

Devesa, J; Pérez-Fernández, R; Bokser, L; Gaudiero, G J; Lima, L; Casanueva, F F

1988-01-01

The aim of the present study was to investigate if the postulated deficient adrenal androgen secretion in Anorexia Nervosa (AN), could be associated with a status of sustained dopaminergic hyperactivity. The adrenal responses to ACTH and PRL response to dopaminergic receptor blockade were studied in seven patients with Anorexia Nervosa and seven regularly menstruating women. AN patients showed lower baseline DHEA-sulphate (DHEA-S), androstenedione (Adione) and prolactin (PRL) levels than controls. The response to ACTH revealed evidences of significantly decreased 17-20 desmolase activity in AN, with apparent predominance of glucocorticoid over androgenic pathways relative to controls. Because dopaminergic receptor blockade with Domperidone (DOM) showed intense dopaminergic hyperactivity in AN, we postulate that the adrenal regression seen in the disease is the consequence of a reduced zona reticularis as a consequence of the lack of trophic support by PRL and/or intermediate lobe proopiomelanocortin (IL-POMC). This is consistent with our previous results in pre-adrenarchal dogs and rabbits.

Apparent Inhibition of β-Fructosidase Secretion by Tunicamycin May Be Explained by Breakdown of the Unglycosylated Protein during Secretion 1

PubMed Central

Faye, Loïc; Chrispeels, Maarten J.

1989-01-01

Suspension-cultured carrot (Daucus carota) cells synthesize and secrete β-fructosidase, a glycoprotein with asparagine-linked glycans. Treatment of the cells with tunicamycin completely inhibits the apparent secretion of β-fructosidase as measured by the accumulation of the radioactive protein in the cell wall or the culture medium. In the past, such a result has been interpreted as an inhibition of secretion by tunicamycin, but we suggest another explanation based on the following results. In the presence of tunicamycin, unglycosylated β-fructosidase is synthesized and is associated with an endoplasmic-reticulum-rich microsomal fraction. Pulse-chase experiments show that the unglycosylated β-fructosidase does not remain in the cells and appears to be secreted in the same way as glycosylated β-fructosidase; however, no radioactive, unglycosylated β-fructosidase accumulates extracellularly (cell wall or medium). Protoplasts obtained from carrot cells secrete β-fructosidase protein and activity, and treatment of the protoplasts with tunicamycin results in the synthesis of unglycosylated β-fructosidase. In the presence of tunicamycin, there is no accumulation of β-fructosidase activity or unglycosylated β-fructosidase polypeptide in the protoplast incubation medium. These results are consistent with the interpretation that the glycans of β-fructosidase are necessary for its stability, and that in these suspension-cultured cells, the unglycosylated enzyme is degraded during the last stage(s) of secretion, or immediately after its arrival in the wall. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:16666631

P1,P4-diadenosine tetraphosphate (Ap4A) inhibits proximal tubular reabsorption of sodium in rats.

PubMed

Stiepanow-Trzeciak, Anna; Jankowski, Maciej; Angielski, Stefan; Szczepanska-Konkel, Miroslawa

2007-01-01

P1,P4-diadenosine tetraphosphate (Ap4A) is a vasoactive dinucleotide possessing natriuretic activity. It is unclear, however, which part of the nephron is the target site of action for Ap4A. We evaluated the tubular sites of Ap4A action using the lithium clearance technique. Ap4A at a priming dose of 2 micromol/kg with subsequent infusion at 20 nmol/kg/min increased fractional water and sodium excretion 2.5- and 5.6-fold, respectively. Moreover, Ap4A increased lithium clearance 1.9-fold and fractional lithium excretion 2.8-fold. Fractional water and sodium excretion from distal nephron segments was not significantly affected by Ap4A. These results suggest that Ap4A induces natriuresis mainly through inhibition of proximal tubular reabsorption of sodium. Copyright 2007 S. Karger AG, Basel.

Neurotensin modulates the composition of pancreatic exocrine secretions in chickens.

PubMed

DeGolier, T F; Place, A R; Duke, G E; Carraway, R E

The effects of neurotensin on pancreatic exocrine secretion were examined in fasted, conscious White Leghorn hens. A cannula was surgically implanted in the central duct serving the ventral lobe of the pancreas in order to collect pure pancreatic juice. Following recovery, neurotensin was infused intravenously at 3.6 or 10.8 pmol/kg*min. The volume and pH of the pancreatic secretions were recorded and total pancreatic protein concentration, amylase, lipase, trypsin, and chymotrypsin activity were measured every 30 min for 2 hr and compared to secretions following the infusion of 0.9% saline. Our results demonstrated that neurotensin did not affect the pH nor the pancreatic juice protein concentration, but did increase secretion rate following neurotensin infusion at 3.6 pmol/kg*min. Amylase activity was significantly depressed during neurotensin infusions, while lipase (both pancreatic and carboxylester lipase) activity was significantly elevated. The ratio of amylase to lipase activity was especially depressed by neurotensin infusion at 10.8 pmol/kg*min. Insufficient secretory activity prevented a balanced statistical analysis of chymotrypsin activity, but from a pooled analysis, neurotensin had no effect on protease activity in the pancreatic juice. These results support our current research indicating that neurotensin may be a hormonal regulator of postprandial lipid digestion in chickens.

Multimodal transport and dispersion of organelles in narrow tubular cells

NASA Astrophysics Data System (ADS)

Mogre, Saurabh S.; Koslover, Elena F.

2018-04-01

Intracellular components explore the cytoplasm via active motor-driven transport in conjunction with passive diffusion. We model the motion of organelles in narrow tubular cells using analytical techniques and numerical simulations to study the efficiency of different transport modes in achieving various cellular objectives. Our model describes length and time scales over which each transport mode dominates organelle motion, along with various metrics to quantify exploration of intracellular space. For organelles that search for a specific target, we obtain the average capture time for given transport parameters and show that diffusion and active motion contribute to target capture in the biologically relevant regime. Because many organelles have been found to tether to microtubules when not engaged in active motion, we study the interplay between immobilization due to tethering and increased probability of active transport. We derive parameter-dependent conditions under which tethering enhances long-range transport and improves the target capture time. These results shed light on the optimization of intracellular transport machinery and provide experimentally testable predictions for the effects of transport regulation mechanisms such as tethering.

Verifiable Secret Redistribution

DTIC Science & Technology

2001-10-01

but they are not trusted with secret. Thus, we require a protocol for redistribution without reconstruction of the secret . We also require...verification that the new shareholders have valid shares (ones that can be used to reconstruct the secret ). We present a new protocol to perform non...secret to shareholders in Shamir’s (m,n) threshold scheme (one in which we require m of n shares to reconstruct the secret ), and wish to redistribute the

Bufadienolides from parotoid gland secretions of Cuban toad Peltophryne fustiger (Bufonidae): Inhibition of human kidney Na(+)/K(+)-ATPase activity.

PubMed

Perera Córdova, Wilmer H; Leitão, Suzana Guimarães; Cunha-Filho, Geraldino; Bosch, Roberto Alonso; Alonso, Isel Pascual; Pereda-Miranda, Rogelio; Gervou, Rodrigo; Touza, Natália Araújo; Quintas, Luis Eduardo M; Noël, François

2016-02-01

Parotoid gland secretions of toad species are a vast reservoir of bioactive molecules with a wide range of biological properties. Herein, for the first time, it is described the isolation by preparative reversed-phase HPLC and the structure elucidation by NMR spectroscopy and/or mass spectrometry of nine major bufadienolides from parotoid gland secretions of the Cuban endemic toad Peltophryne fustiger: ψ-bufarenogin, gamabufotalin, bufarenogin, arenobufagin, 3-(N-suberoylargininyl) marinobufagin, bufotalinin, telocinobufagin, marinobufagin and bufalin. In addition, the secretion was analyzed by UPLC-MS/MS which also allowed the identification of azelayl arginine. The effect of arenobufagin, bufalin and ψ-bufarenogin on Na(+)/K(+)-ATPase activity in a human kidney preparation was evaluated. These bufadienolides fully inhibited the Na(+)/K(+)-ATPase in a concentration-dependent manner, although arenobufagin (IC50 = 28.3 nM) and bufalin (IC50 = 28.7 nM) were 100 times more potent than ψ-bufarenogin (IC50 = 3020 nM). These results provided evidence about the importance of the hydroxylation at position C-14 in the bufadienolide skeleton for the inhibitory activity on the Na(+)/K(+)-ATPase. Published by Elsevier Ltd.

Antifungal activity of the pygidial gland secretion of Laemostenus punctatus (Coleoptera: Carabidae) against cave-dwelling micromycetes

NASA Astrophysics Data System (ADS)

Nenadić, Marija; Ljaljević-Grbić, Milica; Stupar, Miloš; Vukojević, Jelena; Ćirić, Ana; Tešević, Vele; Vujisić, Ljubodrag; Todosijević, Marina; Vesović, Nikola; Živković, Nemanja; Ćurčić, Srećko

2017-06-01

The antifungal potential of the pygidial gland secretion of the troglophilic ground beetle Laemostenus punctatus from a cave in Southeastern Serbia against cave-dwelling micromycetes, isolated from the same habitat, has been investigated. Eleven collected samples were analyzed and 32 isolates of cave-dwelling fungi were documented. A total of 14 fungal species were identified as members of the genera Aspergillus, Penicillium, Alternaria, Cladosporium, Rhizopus, Trichoderma, Arthrinium, Aureobasidium, Epicoccum, Talaromyces, and Fusarium. Five isolates were selected for testing the antifungal activity of the pygidial gland secretion: Talaromyces duclauxi, Aspergillus brunneouniseriatus, Penicillium sp., Rhizopus stolonifer, and Trichoderma viride. The microdilution method has been applied to detect minimal inhibitory concentrations (MICs) and minimal fungicidal concentrations (MFCs). The most sensitive isolate was Penicillium sp., while the other isolates demonstrated a high level of resistance to the tested agent. L. punctatus has developed a special mechanism of producing specific compounds that act synergistically within the secretion mixture, which are responsible for the antifungal action against pathogens from the cave. The results open opportunities for further research in the field of ground beetle defense against pathogens, which could have an important application in human medicine, in addition to the environmental impact, primarily.

Evolving concepts on regulation and function of renin in distal nephron

PubMed Central

Prieto, Minolfa C.; Gonzalez, Alexis A.

2012-01-01

Sustained stimulation of the intrarenal/intratubular renin–angiotensin system in a setting of elevated arterial pressure elicits renal vasoconstriction, increased sodium reabsorption, proliferation, fibrosis, and eventual renal injury. Activation of luminal AT1 receptors in proximal and distal nephron segments by local Ang II formation stimulates various transport systems. Augmented angiotensinogen (AGT) production by proximal tubule cells increases AGT secretion contributing to increased proximal Ang II levels and leading to spillover of AGT into the distal nephron segments, as reflected by increased urinary AGT excretion. The increased distal delivery of AGT provides substrate for renin, which is expressed in principal cells of the collecting tubule and collecting ducts, and is also stimulated by AT1 receptor activation. Renin and prorenin are secreted into the tubular lumen and act on the AGT delivered from the proximal tubule to form more Ang I. The catalytic actions of renin and or prorenin may be enhanced by binding to prorenin receptors on the intercalated cells or soluble prorenin receptor secreted into the tubular fluid. There is also increased luminal angiotensin converting enzyme in collecting ducts facilitating Ang II formation leading to stimulation of sodium reabsorption via sodium channel and sodium/chloride co-transporter. Thus, increased collecting duct renin contributes to Ang II-dependent hypertension by augmenting distal nephron intra-tubular Ang II formation leading to sustained stimulation of sodium reabsorption and progression of hypertension. PMID:22990760

Renal tubular leakage complicating microcephalic osteodysplastic primordial dwarfism.

PubMed Central

Eason, J; Hall, C M; Trounce, J Q

1995-01-01

We describe a male infant with phenotypic and radiological features of microcephalic osteodysplastic primordial dwarfism type I/III. He showed severe osteoporosis and biochemical derangement owing to renal tubular leakage, which has not previously been reported in this condition. He died aged 5 months. Images PMID:7783178

Dynamic modeling of temperature change in outdoor operated tubular photobioreactors.

PubMed

Androga, Dominic Deo; Uyar, Basar; Koku, Harun; Eroglu, Inci

2017-07-01

In this study, a one-dimensional transient model was developed to analyze the temperature variation of tubular photobioreactors operated outdoors and the validity of the model was tested by comparing the predictions of the model with the experimental data. The model included the effects of convection and radiative heat exchange on the reactor temperature throughout the day. The temperatures in the reactors increased with increasing solar radiation and air temperatures, and the predicted reactor temperatures corresponded well to the measured experimental values. The heat transferred to the reactor was mainly through radiation: the radiative heat absorbed by the reactor medium, ground radiation, air radiation, and solar (direct and diffuse) radiation, while heat loss was mainly through the heat transfer to the cooling water and forced convection. The amount of heat transferred by reflected radiation and metabolic activities of the bacteria and pump work was negligible. Counter-current cooling was more effective in controlling reactor temperature than co-current cooling. The model developed identifies major heat transfer mechanisms in outdoor operated tubular photobioreactors, and accurately predicts temperature changes in these systems. This is useful in determining cooling duty under transient conditions and scaling up photobioreactors. The photobioreactor design and the thermal modeling were carried out and experimental results obtained for the case study of photofermentative hydrogen production by Rhodobacter capsulatus, but the approach is applicable to photobiological systems that are to be operated under outdoor conditions with significant cooling demands.

Polycystin-1 Binds Par3/aPKC and Controls Convergent Extension During Renal Tubular Morphogenesis

PubMed Central

Castelli, Maddalena; Boca, Manila; Chiaravalli, Marco; Ramalingam, Harini; Rowe, Isaline; Distefano, Gianfranco; Carroll, Thomas; Boletta, Alessandra

2013-01-01

Several organs, including lungs and kidneys, are formed by epithelial tubes whose proper morphogenesis ensures correct function. This is best exemplified by the kidney, where defective establishment or maintanance of tubular diameter results in polycystic kidney disease, a common genetic disorder. Most polycystic kidney disease cases result from loss-of-function mutations in the PKD1 gene, encoding Polycystin-1 (PC-1), a large receptor of unknown function. Here we demonstrate that PC-1 plays an essential role in establishment of correct tubular diameter during nephron development. PC-1 associates with Par3 favoring the assembly of a pro-polarizing Par3/aPKC complex and it regulates a program of cell polarity important for oriented cell migration and for a convergent extension-like process during tubular morphogenesis. Par3 inactivation in the developing kidney results in defective convergent extension and tubular morphogenesis and in renal cyst formation. Our data define PC-1 as central to cell polarization and to epithelial tube morphogenesis and homeostasis. PMID:24153433

Polycystin-1 binds Par3/aPKC and controls convergent extension during renal tubular morphogenesis

NASA Astrophysics Data System (ADS)

Castelli, Maddalena; Boca, Manila; Chiaravalli, Marco; Ramalingam, Harini; Rowe, Isaline; Distefano, Gianfranco; Carroll, Thomas; Boletta, Alessandra

2013-10-01

Several organs, including the lungs and kidneys, are formed by epithelial tubes whose proper morphogenesis ensures correct function. This is best exemplified by the kidney, where defective establishment or maintenance of tubular diameter results in polycystic kidney disease, a common genetic disorder. Most polycystic kidney disease cases result from loss-of-function mutations in the PKD1 gene, encoding Polycystin-1, a large receptor of unknown function. Here we demonstrate that PC-1 has an essential role in the establishment of correct tubular diameter during nephron development. Polycystin-1 associates with Par3 favouring the assembly of a pro-polarizing Par3/aPKC complex and it regulates a programme of cell polarity important for oriented cell migration and for a convergent extension-like process during tubular morphogenesis. Par3 inactivation in the developing kidney results in defective convergent extension and tubular morphogenesis, and in renal cyst formation. Our data define Polycystin-1 as central to cell polarization and to epithelial tube morphogenesis and homeostasis.

Reactive oxygen species promote tubular injury in diabetic nephropathy: The role of the mitochondrial ros-txnip-nlrp3 biological axis.

PubMed

Han, Yachun; Xu, Xiaoxuan; Tang, Chengyuan; Gao, Peng; Chen, Xianghui; Xiong, Xiaofen; Yang, Ming; Yang, Shikun; Zhu, Xuejing; Yuan, Shuguang; Liu, Fuyou; Xiao, Li; Kanwar, Yashpal S; Sun, Lin

2018-06-01

NLRP3/IL-1β activation via thioredoxin (TRX)/thioredoxin-interacting protein (TXNIP) following mitochondria ROS (mtROS) overproduction plays a key role in inflammation. However, the involvement of this process in tubular damage in the kidneys of patients with diabetic nephropathy (DN) is unclear. Here, we demonstrated that mtROS overproduction is accompanied by decreases in TRX expression and TXNIP up-regulation. In addition, we discovered that mtROS overproduction is also associated with increases in NLRP3/IL-1β and TGF-β expression in the kidneys of patients with DN and db/db mice. We reversed these changes in db/db mice by administering a peritoneal injection of MitoQ, an antioxidant targeting mtROS. Similar results were observed in human tubular HK-2 cells subjected to high-glucose (HG) conditions and treated with MitoQ. Treating HK-2 cells with MitoQ suppressed the dissociation of TRX from TXNIP and subsequently blocked the interaction between TXNIP and NLRP3, leading to the inhibition of NLRP3 inflammasome activation and IL-1β maturation. The effects of MitoQ were enhanced by pretreatment with TXNIP siRNA and abolished by pretreatment with monosodium urate (MSU) and TRX siRNA in vitro. These results suggest that mitochondrial ROS-TXNIP/NLRP3/IL-1β axis activation is responsible for tubular oxidative injury, which can be ameliorated by MitoQ via the inhibition of mtROS overproduction. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Evacuated, displacement compression mold. [of tubular bodies from thermosetting plastics

NASA Technical Reports Server (NTRS)

Heier, W. C. (Inventor)

1974-01-01

A process of molding long thin-wall tubular bodies from thermosetting plastic molding compounds is described wherein the tubular body lengths may be several times the diameters. The process is accomplished by loading a predetermined quantity of molding compound into a female mold cavity closed at one end by a force mandrel. After closing the other end of the female mold with a balance mandrel, the loaded cavity is evacuated by applying a vacuum of from one-to-five mm pressure for a period of fifteen-to-thirty minutes. The mold temperature is raised to the minimum temperature at which the resin constituent of the compound will soften or plasticize and a pressure of 2500 psi is applied.

Unitary reconstruction of secret for stabilizer-based quantum secret sharing

NASA Astrophysics Data System (ADS)

Matsumoto, Ryutaroh

2017-08-01

We propose a unitary procedure to reconstruct quantum secret for a quantum secret sharing scheme constructed from stabilizer quantum error-correcting codes. Erasure correcting procedures for stabilizer codes need to add missing shares for reconstruction of quantum secret, while unitary reconstruction procedures for certain class of quantum secret sharing are known to work without adding missing shares. The proposed procedure also works without adding missing shares.

Authentication Without Secrets

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

Pierson, Lyndon G.; Robertson, Perry J.

This work examines a new approach to authentication, which is the most fundamental security primitive that underpins all cyber security protections. Current Internet authentication techniques require the protection of one or more secret keys along with the integrity protection of the algorithms/computations designed to prove possession of the secret without actually revealing it. Protecting a secret requires physical barriers or encryption with yet another secret key. The reason to strive for "Authentication without Secret Keys" is that protecting secrets (even small ones only kept in a small corner of a component or device) is much harder than protecting the integritymore » of information that is not secret. Promising methods are examined for authentication of components, data, programs, network transactions, and/or individuals. The successful development of authentication without secret keys will enable far more tractable system security engineering for high exposure, high consequence systems by eliminating the need for brittle protection mechanisms to protect secret keys (such as are now protected in smart cards, etc.). This paper is a re-release of SAND2009-7032 with new figures numerous edits.« less

Dual effect of cell-cell contact disruption on cytosolic calcium and insulin secretion.

PubMed

Jaques, Fabienne; Jousset, Hélène; Tomas, Alejandra; Prost, Anne-Lise; Wollheim, Claes B; Irminger, Jean-Claude; Demaurex, Nicolas; Halban, Philippe A

2008-05-01

Cell-to-cell interactions play an important role in insulin secretion. Compared with intact islets, dispersed pancreatic beta-cells show increased basal and decreased glucose-stimulated insulin secretion. In this study, we used mouse MIN6B1 cells to investigate the mechanisms that control insulin secretion when cells are in contact with each other or not. RNAi-mediated silencing of the adhesion molecule E-cadherin in confluent cells reduced glucose-stimulated secretion to the levels observed in isolated cells but had no impact on basal secretion. Dispersed cells presented high cytosolic Ca(2+) activity, depolymerized cytoskeleton and ERK1/2 activation in low glucose conditions. Both the increased basal secretion and the spontaneous Ca(2+) activity were corrected by transient removal of Ca(2+) or prolonged incubation of cells in low glucose, a procedure that restored the ability of dispersed cells to respond to glucose (11-fold stimulation). In conclusion, we show that dispersed pancreatic beta-cells can respond robustly to glucose once their elevated basal secretion has been corrected. The increased basal insulin secretion of dispersed cells is due to spontaneous Ca(2+) transients that activate downstream Ca(2+) effectors, whereas engagement of cell adhesion molecules including E-cadherin contributes to the greater secretory response to glucose seen in cells with normal intercellular contacts.

Investigation on the Effect of Initial Welding Imperfection on Fatigue strength of Tubular Member by FEM

NASA Astrophysics Data System (ADS)

Chang, Kyong-Ho; Shin, Wang Sub; Nguyen Van Vuong, Do; Lee, Chin Hyeong

2018-04-01

Steel tube structure is used for steel structure such as offshore platform, bridges and so on. Also, all circular members of tubular structures are mainly connected by welding. When the steel tubular structures are subjected to repeated loading, not only the load carrying capacity is reduced but also fatigue cracks may develop at the joint part of steel tubular members which are connected by welding. Carrying out welding, welding initial imperfection such as welding deformation and residual stress are inevitably generated at weld part. It was well known that the effect of welding residual and welding deformation on fatigue strength. However, It’s not clear which affects fatigue strength more. However, it’s difficult to clear the effect on fatigue strength by experiment. To clarify these effect, fatigue analysis was carried out by FEM which is based on continuum damage mechanics. On the other hand, coupled three-dimensional non-steady heat conduction analysis, and the thermal elastic-plastic analysis was carried out to reproduce the initial weld state of tubular member. From the result, not only the fatigue strength of welded tubular member but also the fatigue life could be found by FEM fatigue analysis.

Pediatric Tubular Pulmonary Heart Valve from Decellularized Engineered Tissue Tubes

PubMed Central

Reimer, Jay M.; Syedain, Zeeshan H.; Haynie, Bee H.T.; Tranquillo, Robert T.

2015-01-01

Pediatric patients account for a small portion of the heart valve replacements performed, but a pediatric pulmonary valve replacement with growth potential remains an unmet clinical need. Herein we report the first tubular heart valve made from two decellularized, engineered tissue tubes attached with absorbable sutures, which can meet this need, in principle. Engineered tissue tubes were fabricated by allowing ovine dermal fibroblasts to replace a sacrificial fibrin gel with an aligned, cell-produced collagenous matrix, which was subsequently decellularized. Previously, these engineered tubes became extensively recellularized following implantation into the sheep femoral artery. Thus, a tubular valve made from these tubes may be amenable to recellularization and, ideally, somatic growth. The suture line pattern generated three equi-spaced “leaflets” in the inner tube, which collapsed inward when exposed to back pressure, per tubular valve design. Valve testing was performed in a pulse duplicator system equipped with a secondary flow loop to allow for root distention. All tissue-engineered valves exhibited full leaflet opening and closing, minimal regurgitation (< 5%), and low systolic pressure gradients (< 2.5 mmHg) under pulmonary conditions. Valve performance was maintained under various trans-root pressure gradients and no tissue damage was evident after 2 million cycles of fatigue testing. PMID:26036175

Minimally Invasive Tubular Resection of Lumbar Synovial Cysts: Report of 40 Consecutive Cases.

PubMed

Birch, Barry D; Aoun, Rami James N; Elbert, Gregg A; Patel, Naresh P; Krishna, Chandan; Lyons, Mark K

2016-10-01

Lumbar synovial cysts are a relatively common clinical finding. Surgical treatment of symptomatic synovial cysts includes computed tomography-guided aspiration, open resection and minimally invasive tubular resection. We report our series of 40 consecutive minimally invasive microscopic tubular lumbar synovial cyst resections. Following Institutional Review Board approval, a retrospective analysis of 40 cases of minimally invasive microscopic tubular retractor synovial cyst resections at a single institution by a single surgeon (B.D.B.) was conducted. Gross total resection was performed in all cases. Patient characteristics, surgical operating time, complications, and outcomes were analyzed. Lumbar radiculopathy was the presenting symptoms in all but 1 patient, who presented with neurogenic claudication. The mean duration of symptoms was 6.5 months (range, 1-25 months), mean operating time was 58 minutes (range, 25-110 minutes), and mean blood loss was 20 mL (range, 5-50 mL). Seven patients required overnight observation. The median length of stay in the remaining 33 patients was 4 hours. There were 2 cerebrospinal fluid leaks repaired directly without sequelae. The mean follow-up duration was 80.7 months. Outcomes were good or excellent in 37 of the 40 patients, fair in 1 patient, and poor in 2 patients. Minimally invasive microscopic tubular retractor resection of lumbar synovial cysts can be done safely and with comparable outcomes and complication rates as open procedures with potentially reduced operative time, length of stay, and healthcare costs. Patient selection for microscopic tubular synovial cyst resection is based in part on the anatomy of the spine and synovial cyst and is critical when recommending minimally invasive vs. open resection to patients. Copyright © 2016 Elsevier Inc. All rights reserved.

New Markers of Inflammation and Tubular Damage in Children with Chronic Kidney Disease.

PubMed

Musiał, Kinga; Bargenda, Agnieszka; Drożdż, Dorota; Zwolińska, Danuta

2017-01-01

Monocyte chemoattractant protein- (MCP-) 1, macrophage colony-stimulating factor (MCSF), and neopterin are connected with monocyte migration and transition into macrophages, leading to fibrosis and tubular damage in the course of CKD. The aim of the study was to analyze the applicability of urinary fractional excretion (FE) of MCP1, MCSF, and neopterin, as markers of inflammation and tubular damage, in children with CKD. The study group consisted of 61 children with CKD stages 1-5 and 23 age-matched controls. The serum and urine concentrations of MCP1, MCSF, and neopterin were assessed by ELISA and then the fractional excretion (FE) was calculated. FE MCSF and neopterin values exceeded 1% already in controls. FE MCSF rose significantly since CKD stages 1-2, FE neopterin since CKD stages 3-5. FE MCP1 was below 1% in healthy controls and in CKD stages 1-2, then increased significantly in CKD stages 3-5. The FE MCP-1 values show that inflammation precedes the tubular dysfunction. FE MCSF and FE neopterin may be considered new markers of the renal parenchyma progressive damage. Fractional excretion may become a useful tool in the assessment of inflammation and tubular damage in children with CKD.

Indoxyl Sulfate Induces Apoptosis and Hypertrophy in Human Kidney Proximal Tubular Cells.

PubMed

Ellis, Robert J; Small, David M; Ng, Keng Lim; Vesey, David A; Vitetta, Luis; Francis, Ross S; Gobe, Glenda C; Morais, Christudas

2018-06-01

Indoxyl sulfate (IS) is a protein-bound uremic toxin that accumulates in patients with declining kidney function. Although generally thought of as a consequence of declining kidney function, emerging evidence demonstrates direct cytotoxic role of IS on endothelial cells and cardiomyocytes, largely through the expression of pro-inflammatory and pro-fibrotic factors. The direct toxicity of IS on human kidney proximal tubular epithelial cells (PTECs) remains a matter of debate. The current study explored the effect of IS on primary cultures of human PTECs and HK-2, an immortalized human PTEC line. Pathologically relevant concentrations of IS induced apoptosis and increased the expression of the proapoptotic molecule Bax in both cell types. IS impaired mitochondrial metabolic activity and induced cellular hypertrophy. Furthermore, statistically significant upregulation of pro-fibrotic (transforming growth factor-β, fibronectin) and pro-inflammatory molecules (interleukin-6, interleukin-8, and tumor necrosis factor-α) in response to IS was observed. Albumin had no influence on the toxicity of IS. The results of this study suggest that IS directly induced a pro-inflammatory and pro-fibrotic phenotype in proximal tubular cells. In light of the associated apoptosis, hypertrophy, and metabolic dysfunction, this study demonstrates that IS may play a role in the progression of chronic kidney disease.

LcrQ and SycH function together at the Ysc type III secretion system in Yersinia pestis to impose a hierarchy of secretion.

PubMed

Wulff-Strobel, Christine R; Williams, Andrew W; Straley, Susan C

2002-01-01

LcrQ is a regulatory protein unique to Yersinia. Previous study in Yersinia pseudotuberculosis and Yersinia enterocolitica prompted the model in which LcrQ negatively regulates the expression of a set of virulence proteins called Yops, and its secretion upon activation of the Yop secretion (Ysc) type III secretion system permits full induction of Yops expression. In this study, we tested the hypothesis that LcrQ's effects on Yops expression might be indirect. Excess LcrQ was found to exert an inhibitory effect specifically at the level of Yops secretion, independent of production, and a normal inner Ysc gate protein LcrG was required for this activity. However, overexpression of LcrQ did not prevent YopH secretion, suggesting that LcrQ's effects at the Ysc discriminate among the Yops. We tested this idea by determining the effects of deletion or overexpression of LcrQ, YopH and their common chaperone SycH on early Yop secretion through the Ysc. Together, our findings indicated that LcrQ is not a negative regulator directly, but it acts in partnership with SycH at the Ysc gate to control the entry of a set of Ysc secretion substrates. A hierarchy of YopH secretion before YopE appears to be imposed by SycH in conjunction with both LcrQ and YopH. LcrQ and SycH in addition influenced the deployment of LcrV, a component of the Yops delivery mechanism. Accordingly, LcrQ appears to be a central player in determining the substrate specificity of the Ysc.

Modification of tubular ceramic membranes with carbon nanotubes using catalytic chemical vapor deposition.

PubMed

Tran, Duc Trung; Thieffry, Guillemette; Jacob, Matthieu; Batiot-Dupeyrat, Catherine; Teychene, Benoit

2015-01-01

In this study, carbon nanotubes (CNTs) were successfully grown on tubular ceramic membranes using the catalytic chemical vapor deposition (CCVD) method. CNTs were synthesized at 650°C for 3-6 h under a 120 mL min(-1) flow of C2H6 on ceramic membranes impregnated with iron salt. The synthesis procedure was beforehand optimized in terms of catalyst amount, impregnation duration and reaction temperature, using small pieces of tubular ceramic membranes. The yield, size and structure of the CNTs produced were characterized using thermogravimetric analysis and microscopic imaging techniques. Afterwards, preliminary filtration tests with alginate and phenol were performed on two modified tubular membranes. The results indicate that the addition of CNTs on the membrane material increased the permeability of ceramic membrane and its ability to reject alginate and adsorb phenol, yet decreased its fouling resistance.

Resveratrol prevents high glucose-induced epithelial-mesenchymal transition in renal tubular epithelial cells by inhibiting NADPH oxidase/ROS/ERK pathway.

PubMed

He, Ting; Guan, Xu; Wang, Song; Xiao, Tangli; Yang, Ke; Xu, Xinli; Wang, Junping; Zhao, Jinghong

2015-02-15

Resveratrol (RSV) is reported to have renoprotective activity against diabetic nephropathy, while the mechanisms underlying its function have not been fully elucidated. In this study, we investigate the effect and related mechanism of RSV against high glucose-induced epithelial to mesenchymal transition (EMT) in human tubular epithelial cells (HK-2). A typical EMT is induced by high glucose in HK-2 cells, accompanied by increased levels of reactive oxygen species (ROS). RSV exhibits a strong ability to inhibit high glucose-induced EMT by decreasing intracellular ROS levels via down-regulation of NADPH oxidase subunits NOX1 and NOX4. The activation of extracellular signal-regulated kinase (ERK1/2) is found to be involved in high glucose-induced EMT in HK-2 cells. RSV, like NADPH oxidase inhibitor diphenyleneiodonium, can block ERK1/2 activation induced by high glucose. Our results demonstrate that RSV is a potent agent against high glucose-induced EMT in renal tubular cells via inhibition of NADPH oxidase/ROS/ERK1/2 pathway. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Exciton Level Structure and Dynamics in Tubular Porphyrin Aggregates

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

Wan, Yan; Stradomska, Anna; Fong, Sarah

2014-10-30

We present an account of the optical properties of the Frenkel excitons in self-assembled porphyrin tubular aggregates that represent an analog to natural photosynthetic antennae. Using a combination of ultrafast optical spectroscopy and stochastic exciton modeling, we address both linear and nonlinear exciton absorption, relaxation pathways, and the role of disorder. The static disorder-dominated absorption and fluorescence line widths show little temperature dependence for the lowest excitons (Q band), which we successfully simulate using a model of exciton scattering on acoustic phonons in the host matrix. Temperature-dependent transient absorption of and fluorescence from the excitons in the tubular aggregates aremore » marked by nonexponential decays with time scales ranging from a few picoseconds to a few nanoseconds, reflecting complex relaxation mechanisms. Combined experimental and theoretical investigations indicate that nonradiative pathways induced by traps and defects dominate the relaxation of excitons in the tubular aggregates. We model the pumpprobe spectra and ascribe the excited-state absorption to transitions from one-exciton states to a manifold of mixed one- and two-exciton states. Our results demonstrate that while the delocalized Frenkel excitons (over 208 (1036) molecules for the optically dominant excitons in the Q (B) band) resulting from strong intermolecular coupling in these aggregates could potentially facilitate efficient energy transfer, fast relaxation due to defects and disorder probably present a major limitation for exciton transport over large distances.« less

Modulation of insulin secretion by fatty acyl analogs.

PubMed

Las, Guy; Mayorek, Nina; Dickstein, Kobie; Bar-Tana, Jacob

2006-12-01

The secretagogue, the incretin-like, and the suppressive activities of long-chain fatty acids (LCFAs) in modulating insulin secretion in vivo and in cultured islets were simulated here by beta,beta'-tetramethyl-hexadecanedioic acid (M16) and alpha,alpha'-tetrachloro-tetradecanedioic acid (Cl-DICA). M16, but not Cl-DICA, serves as a substrate for ATP-dependent CoA thioesterification but is not further metabolized. M16, but not Cl-DICA, acted as a potent insulin secretagogue in islets cultured in basal but not high glucose. Short-term exposure to M16 or Cl-DICA resulted in activation of glucose- but not arginine-stimulated insulin secretion. Long-term exposure to M16, but not to Cl-DICA, resulted in suppression of glucose-, arginine-, and K(+)-stimulated insulin secretion; inhibition of glucose-induced proinsulin biosynthesis; and depletion of islets insulin. beta-Cell mass and islet ATP content remained unaffected. Hence, nonmetabolizable LCFA analogs may highlight discrete LCFA metabolites and pathways involved in modulating insulin secretion, which could be overlooked due to the rapid turnover of natural LCFA.

Sirt1 protects against oxidative stress-induced renal tubular cell apoptosis by the bidirectional regulation of catalase expression

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

Hasegawa, Kazuhiro; Wakino, Shu; Yoshioka, Kyoko

2008-07-18

NAD{sup +}-dependent protein deacetylase Sirt1 regulates cellular apoptosis. We examined the role of Sirt1 in renal tubular cell apoptosis by using HK-2 cells, proximal tubular cell lines with or without reactive oxygen species (ROS), H{sub 2}O{sub 2}. Without any ROS, Sirt1 inhibitors enhanced apoptosis and the expression of ROS scavenger, catalase, and Sirt1 overexpression downregulated catalase. When apoptosis was induced with H{sub 2}O{sub 2}, Sirt1 was upregulated with the concomitant increase in catalase expression. Sirt1 overexpression rescued H{sub 2}O{sub 2}-induced apoptosis through the upregulation of catalase. H{sub 2}O{sub 2} induced the nuclear accumulation of forkhead transcription factor, FoxO3a and themore » gene silencing of FoxO3a enhanced H{sub 2}O{sub 2}-induced apoptosis. In conclusion, endogenous Sirt1 maintains cell survival by regulating catalase expression and by preventing the depletion of ROS required for cell survival. In contrast, excess ROS upregulates Sirt1, which activates FoxO3a and catalase leading to rescuing apoptosis. Thus, Sirt1 constitutes a determinant of renal tubular cell apoptosis by regulating cellular ROS levels.« less

Apparent inhibition of. beta. -fructosidase secretion by tunicamycin may be explained by breakdown of the unglycosylated protein during secretion. [Daucus carota

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

Faye, L.; Chrispeels, M.J.

1989-03-01

Suspension-cultured carrot (Daucus carota) cells synthesize and secrete {beta}-fructosidase, a glycoprotein with asparagine-linked glycans. Treatment of the cells with tunicamycin completely inhibits the apparent secretion of {beta}-fructosidase as measured by the accumulation of the {sup 35}S-labelled protein in the cell wall or the culture medium. In the past, such a result has been interpreted as an inhibition of secretion by tunicamycin, but we suggest another explanation based on the following results. In the presence of tunicamycin, unglycosylated {beta}-fructosidase is synthesized and is associated with an endoplasmic-reticulum-rich microsomal fraction. Pulse-chase experiments show that the unglycosylated {beta}-fructosidase does not remain in themore » cells and appears to be secreted in the same way as glycosylated {beta}-fructosidase; however, no radioactive, unglycosylated {beta}-fructosidase accumulates extracellularly (cell wall or medium). Protoplasts obtained from carrot cells secrete {beta}-fructosidase protein and activity, and treatment of the protoplasts with tunicamycin results in the synthesis of unglycosylated {beta}-fructosidase. In the presence of tunicamycin, there is no accumulation of {beta}-fructosidase activity or unglycosylated {beta}-fructosidase polypeptide in the protoplast incubation medium. These results are consistent with the interpretation that the glycans of {beta}-fructosidase are necessary for its stability, and that in these suspension-cultured cells, the unglycosylated enzyme is degraded during the last stage(s) of secretion, or immediately after its arrival in the wall.« less

Acidity enhances the effectiveness of active chemical defensive secretions of sea hares, Aplysia californica, against spiny lobsters, Panulirus interruptus.

PubMed

Shabani, Shkelzen; Yaldiz, Seymanur; Vu, Luan; Derby, Charles D

2007-12-01

Sea hares such as Aplysia californica, gastropod molluscs lacking a protective shell, can release a purple cloud of chemicals when vigorously attacked by predators. This active chemical defense is composed of two glandular secretions, ink and opaline, both of which contain an array of compounds. This secretion defends sea hares against predators such as California spiny lobsters Panulirus interruptus via multiple mechanisms, one of which is phagomimicry, in which secretions containing feeding chemicals attract and distract predators toward the secretion and away from the sea hare. We show here that ink and opaline are highly acidic, both having a pH of approximately 5. We examined if the acidity of ink and opaline affects their phagomimetic properties. We tested behavioral and electrophysiological responses of chemoreceptor neurons in the olfactory and gustatory organs of P. interruptus, to ink and opaline of A. californica within their natural range of pH values, from approximately 5 to 8. Both behavioral and electrophysiological responses to ink and opaline were enhanced at low pH, and low pH alone accounted for most of this effect. Our data suggest that acidity enhances the phagomimetic chemical defense of sea hares.

76 FR 39071 - Certain Oil Country Tubular Goods From the People's Republic of China: Rescission of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-05

... DEPARTMENT OF COMMERCE International Trade Administration [C-570-944] Certain Oil Country Tubular... administrative review of the countervailing duty order on certain oil country tubular goods (``OCTG'') from the... subject to administrative protective order (``APO'') of their responsibility concerning the disposition of...

Inappropriate Vasopressin Secretion (SIADH) in Burned Patients

DTIC Science & Technology

1983-03-01

cular route, can promote the secretion of AVP in animals effective arterial volume relative to increased metabolic (24, 28, 29). Plasma renin activity...caloric intake (estimated resting metabolic (ileus or obtundation) were considered separately (Figs. rate, +25%) was begun in the first week. Morphine...further suggest adequate effective volume. for AVP secretion is set at a lower than normal plasma Whether the hypermetabolic state and increased O de

Nonimaging secondary concentrators for large rim angle parabolic troughs with tubular absorbers.

PubMed

Ries, H; Spirkl, W

1996-05-01

For parabolic trough solar collectors with tubular absorbers, we design new tailored secondary concentrators. The design is applicable for any rim angle of a parabolic reflector. With the secondary, the concentration can be increased by a factor of more than 2 with a compact secondary reflector consisting of a single piece, even for the important case of a rim angle of 90 deg. The parabolic reflector can be used without changes; the reduced absorber is still tubular but smaller than the original absorber and slightly displaced toward the primary.

Tubular forms of papova viruses in human laryngeal papilloma.

PubMed

Arnold, W

1979-01-01

In two cases of recurrent laryngeal papillomatosis tubular forms of papova viruses could be observed. The same material revealed the close relation between nuclear chromatine and the release of particles, as well as a capsomere like substructure of the virions.

In vivo antibody-mediated modulation of aminopeptidase A in mouse proximal tubular epithelial cells.

PubMed

Mentzel, S; Dijkman, H B; van Son, J P; Wetzels, J F; Assmann, K J

1999-07-01

Aminopeptidase A (APA) is one of the many renal hydrolases. In mouse kidney, APA is predominantly expressed on the brush borders and sparsely on the basolateral membranes of proximal tubular epithelial cells. However, when large amounts of monoclonal antibodies (MAbs) against APA were injected into mice, we observed strong binding of the MAbs to the basolateral membranes, whereas the MAbs bound only transiently to the brush borders of the proximal tubular epithelial cells. In parallel, APA itself disappeared from the brush borders by both endocytosis and shedding, whereas it was increasingly expressed on the basolateral sides. Using ultrastructural immunohistology, we found no evidence for transcellular transport of endocytosed APA to the basolateral side of the proximal tubular epithelial cells. The absence of transcellular transport was confirmed by experiments in which we used a low dose of the MAbs. Such a low dose did not result in binding of the MAbs to the brush borders and had no effect on the presence of APA in the brush borders of the proximal tubular epithelial cells. In these experiments we still could observe binding of the MAbs to the basolateral membranes in parallel with the local appearance of APA. In addition, treatment of mice with chlorpromazine, a calmodulin antagonist that interferes with cytoskeletal function, largely inhibited the MAb-induced modulation of APA. Our studies suggest that injection of MAbs to APA specifically interrupts the normal intracellular traffic of this enzyme in proximal tubular epithelial cells. This intracellular transport is dependent on the action of cytoskeletal proteins.

Potential influence of tubular dysfunction on the difference between estimated and measured glomerular filtration rate after kidney transplantation.

PubMed

Lezaic, V; Mirkovic, D; Ristic, S; Radivojevic, D; Dajak, M; Naumovic, R; Marinkovic, J; Djukanovic, L J

2013-05-01

Because no consensus exists regarding the most accurate calculation to estimate glomerular filtration rate (GFR) based on serum creatinine concentrations (sCr) after kidney transplantation, this study sought to assess the potential role of tubular dysfunction on GFR estimates using various equations as well as the effect of pharmacologic blockades on tubular secretion of creatinine on creatinine clearance (ClCr). Iohexol GFR (mGFR) was performed in 17 stable kidney transplant recipients(R) at >24 months post-transplantation. Their mean age was 48.3 ± 11.3 years. All R were treated with a calcineurin inhibitor (CNI). At the time of study we measured sCr, 24 hour-ClCr, cystatin C, 24-hour proteinuria, microalbuminuria, FE Na, alfa1-microglobulinuria (alfa1-MG), and CNI concentrations. To block tubular secretion of Cr, recipients were prescribed cimetidine (2400 mg) 2 days before the sCr measurement. Additionally, to exclude dietary influences on sCr, R did not eat meat for 2 days before testing. GFR was estimated using the Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Cockroft-Gault (C&G), and Cystatin C (Cyst C) GFR equations. Mean kidney graft function over the previous 6 months was used as the control. Pearson correlation was determined between the differences between mGFR and estimatedGFR: Iohexol minus MDRD, EPI, Cyst C or C&G GFR for paired estimates. The diagnostic accuracy of the eGFRs to detect an mGFR of 60 mL/min/1.73 m(2) was examined by receiver operating characteristic curves. Mean mGFR was 75.2 ± 35.8 mL/min/1.73 m(2). The sCr increased but the 24-hour ClCr, MDRD, EPI, and C&G decreased after vs before cimetidine. The difference was significant for sCr (F = 12.933; P = .002) and MDRD GFR (F = 15.750; P = .001). mGFR was not significantly higher than all pair values of eGFRs, and not significantly lower than 24-hour ClCr before and after cimetidine. However, in comparison to all eGFRs, Cl

Characterization of Shikonin Derivative Secretion in Lithospermum erythrorhizon Hairy Roots as a Model of Lipid-Soluble Metabolite Secretion from Plants

PubMed Central

Tatsumi, Kanade; Yano, Mariko; Kaminade, Kenta; Sugiyama, Akifumi; Sato, Mayuko; Toyooka, Kiminori; Aoyama, Takashi; Sato, Fumihiko; Yazaki, Kazufumi

2016-01-01

Shikonin derivatives are specialized lipophilic metabolites, secreted in abundant amounts from the root epidermal cells of Lithospermum erythrorhizon. Because they have anti-microbial activities, these compounds, which are derivatives of red naphthoquinone, are thought to serve as a chemical barrier for plant roots. The mechanism by which they are secreted from cells is, however, largely unknown. The shikonin production system in L. erythrorhizon is an excellent model for studying the mechanism by which lipophilic compounds are secreted from plant cells, because of the abundant amounts of these compounds produced by L. erythrorhizon, the 0 to 100% inducibility of their production, the light-specific inhibition of production, and the visibility of these products as red pigments. To date, many factors regulating shikonin biosynthesis have been identified, but no mechanism that regulates shikonin secretion without inhibiting biosynthesis has been detected. This study showed that inhibitors of membrane traffic strongly inhibit shikonin secretion without inhibiting shikonin production, suggesting that the secretion of shikonin derivatives into the apoplast utilizes pathways common to the ADP-ribosylation factor/guanine nucleotide exchange factor (ARF/GEF) system and actin filament polymerization, at least in part. These findings provide clues about the machinery involved in secreting lipid-soluble metabolites from cells. PMID:27507975

Characterization of Shikonin Derivative Secretion in Lithospermum erythrorhizon Hairy Roots as a Model of Lipid-Soluble Metabolite Secretion from Plants.

PubMed

Tatsumi, Kanade; Yano, Mariko; Kaminade, Kenta; Sugiyama, Akifumi; Sato, Mayuko; Toyooka, Kiminori; Aoyama, Takashi; Sato, Fumihiko; Yazaki, Kazufumi

2016-01-01

Shikonin derivatives are specialized lipophilic metabolites, secreted in abundant amounts from the root epidermal cells of Lithospermum erythrorhizon. Because they have anti-microbial activities, these compounds, which are derivatives of red naphthoquinone, are thought to serve as a chemical barrier for plant roots. The mechanism by which they are secreted from cells is, however, largely unknown. The shikonin production system in L. erythrorhizon is an excellent model for studying the mechanism by which lipophilic compounds are secreted from plant cells, because of the abundant amounts of these compounds produced by L. erythrorhizon, the 0 to 100% inducibility of their production, the light-specific inhibition of production, and the visibility of these products as red pigments. To date, many factors regulating shikonin biosynthesis have been identified, but no mechanism that regulates shikonin secretion without inhibiting biosynthesis has been detected. This study showed that inhibitors of membrane traffic strongly inhibit shikonin secretion without inhibiting shikonin production, suggesting that the secretion of shikonin derivatives into the apoplast utilizes pathways common to the ADP-ribosylation factor/guanine nucleotide exchange factor (ARF/GEF) system and actin filament polymerization, at least in part. These findings provide clues about the machinery involved in secreting lipid-soluble metabolites from cells.

Effect of taurine on advanced glycation end products-induced hypertrophy in renal tubular epithelial cells

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

Huang, J.-S.; Chuang, L.-Y.; Guh, J.-Y.

2008-12-01

Mounting evidence indicates that advanced glycation end products (AGE) play a major role in the development of diabetic nephropathy (DN). Taurine is a well documented antioxidant agent. To explore whether taurine was linked to altered AGE-mediated renal tubulointerstitial fibrosis in DN, we examined the molecular mechanisms of taurine responsible for inhibition of AGE-induced hypertrophy in renal tubular epithelial cells. We found that AGE (but not non-glycated BSA) caused inhibition of cellular mitogenesis rather than cell death by either necrosis or apoptosis. There were no changes in caspase 3 activity, bcl-2 protein expression, and mitochondrial cytochrome c release in BSA, AGE,more » or the antioxidant taurine treatments in these cells. AGE-induced the Raf-1/extracellular signal-regulated kinase (ERK) activation was markedly blocked by taurine. Furthermore, taurine, the Raf-1 kinase inhibitor GW5074, and the ERK kinase inhibitor PD98059 may have the ability to induce cellular proliferation and cell cycle progression from AGE-treated cells. The ability of taurine, GW5074, or PD98059 to inhibit AGE-induced hypertrophy was verified by the observation that it significantly decreased cell size, cellular hypertrophy index, and protein levels of RAGE, p27{sup Kip1}, collagen IV, and fibronectin. The results obtained in this study suggest that taurine may serve as the potential anti-fibrotic activity in DN through mechanism dependent of its Raf-1/ERK inactivation in AGE-induced hypertrophy in renal tubular epithelial cells.« less

Transforming Growth Factor Beta 1 Drives a Switch in Connexin Mediated Cell-to-Cell Communication in Tubular Cells of the Diabetic Kidney.

PubMed

Hills, Claire; Price, Gareth William; Wall, Mark John; Kaufmann, Timothy John; Chi-Wai Tang, Sidney; Yiu, Wai Han; Squires, Paul Edward

2018-01-01

Changes in cell-to-cell communication have been linked to several secondary complications of diabetes, but the mechanism by which connexins affect disease progression in the kidney is poorly understood. This study examines a role for glucose-evoked changes in the beta1 isoform of transforming growth factor (TGFβ1), on connexin expression, gap-junction mediated intercellular communication (GJIC) and hemi-channel ATP release from tubular epithelial cells of the proximal renal nephron. Biopsy material from patients with and without diabetic nephropathy was stained for connexin-26 (CX26) and connexin-43 (CX43). Changes in expression were corroborated by immunoblot analysis in human primary proximal tubule epithelial cells (hPTECs) and model epithelial cells from human renal proximal tubules (HK2) cultured in either low glucose (5mmol/L) ± TGFβ1 (2-10ng/ml) or high glucose (25mmol/L) for 48h or 7days. Secretion of the cytokine was determined by ELISA. Paired whole cell patch clamp recordings were used to measure junctional conductance in control versus TGFβ1 treated (10ng/ml) HK2 cells, with carboxyfluorescein uptake and ATP-biosensing assessing hemi-channel function. A downstream role for ATP in mediating the effects of TGF-β1 on connexin mediated cell communication was assessed by incubating cells with ATPγS (1-100µM) or TGF-β1 +/- apyrase (5 Units/ml). Implications of ATP release were measured through immunoblot analysis of interleukin 6 (IL-6) and fibronectin expression. Biopsy material from patients with diabetic nephropathy exhibited increased tubular expression of CX26 and CX43 (P<0.01, n=10), data corroborated in HK2 and hPTEC cells cultured in TGFβ1 (10ng/ml) for 7days (P<0.001, n=3). High glucose significantly increased TGFβ1 secretion from tubular epithelial cells (P<0.001, n=3). The cytokine (10ng/ml) reduced junctional conductance between HK2 cells from 4.5±1.3nS in control to 1.15±0.9nS following 48h TGFβ1 and to 0.42±0.2nS after 7days TGFβ1

Calcium-activated chloride channel TMEM16A modulates mucin secretion and airway smooth muscle contraction.

PubMed

Huang, Fen; Zhang, Hongkang; Wu, Meng; Yang, Huanghe; Kudo, Makoto; Peters, Christian J; Woodruff, Prescott G; Solberg, Owen D; Donne, Matthew L; Huang, Xiaozhu; Sheppard, Dean; Fahy, John V; Wolters, Paul J; Hogan, Brigid L M; Finkbeiner, Walter E; Li, Min; Jan, Yuh-Nung; Jan, Lily Yeh; Rock, Jason R

2012-10-02

Mucous cell hyperplasia and airway smooth muscle (ASM) hyperresponsiveness are hallmark features of inflammatory airway diseases, including asthma. Here, we show that the recently identified calcium-activated chloride channel (CaCC) TMEM16A is expressed in the adult airway surface epithelium and ASM. The epithelial expression is increased in asthmatics, particularly in secretory cells. Based on this and the proposed functions of CaCC, we hypothesized that TMEM16A inhibitors would negatively regulate both epithelial mucin secretion and ASM contraction. We used a high-throughput screen to identify small-molecule blockers of TMEM16A-CaCC channels. We show that inhibition of TMEM16A-CaCC significantly impairs mucus secretion in primary human airway surface epithelial cells. Furthermore, inhibition of TMEM16A-CaCC significantly reduces mouse and human ASM contraction in response to cholinergic agonists. TMEM16A-CaCC blockers, including those identified here, may positively impact multiple causes of asthma symptoms.

The impact of pregnancy on anti-HIV activity of cervicovaginal secretions.

PubMed

Hughes, Brenna L; Dutt, Riana; Raker, Christina; Barthelemy, Melody; Rossoll, Richard M; Ramratnam, Bharat; Wira, Charles R; Cu-Uvin, Susan

2016-12-01

trimesters, pregnant women experienced suppression of several cervicovaginal immune mediators that included human beta defensin-2; lactoferrin; macrophage inflammatory protein-3α; regulated on activation, normally T-cell expressed and secreted; and stromal cell-derived factor-1 (all P≤.05). The antimicrobial peptide elafin was significantly correlated with HIV infectivity in both groups across all visits, except at the postpartum visit in the pregnant group (n=16). Secretory leukocyte protease inhibitor also was correlated significantly with infectivity across all visits, but in nonpregnant women only (P≤.03). Cervicovaginal secretions from both pregnant and nonpregnant women contain immune mediators that are associated with HIV infectivity in an in vitro assay; however, infectivity was not different between pregnant and nonpregnant groups. If pregnant women are at increased risk for HIV infection, it is unlikely to be mediated by alterations in the effectiveness of these protective secretions. Copyright © 2016 Elsevier Inc. All rights reserved.

Extracellular heat shock protein HSP90{beta} secreted by MG63 osteosarcoma cells inhibits activation of latent TGF-{beta}1

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

Suzuki, Shigeki; Kulkarni, Ashok B., E-mail: ak40m@nih.gov

2010-07-30

Transforming growth factor-beta 1 (TGF-{beta}1) is secreted as a latent complex, which consists of latency-associated peptide (LAP) and the mature ligand. The release of the mature ligand from LAP usually occurs through conformational change of the latent complex and is therefore considered to be the first step in the activation of the TGF-{beta} signaling pathway. So far, factors such as heat, pH changes, and proteolytic cleavage are reportedly involved in this activation process, but the precise molecular mechanism is still far from clear. Identification and characterization of the cell surface proteins that bind to LAP are important to our understandingmore » of the latent TGF-{beta} activation process. In this study, we have identified heat shock protein 90 {beta} (HSP90{beta}) from the cell surface of the MG63 osteosarcoma cell line as a LAP binding protein. We have also found that MG63 cells secrete HSP90{beta} into extracellular space which inhibits the activation of latent TGF-{beta}1, and that there is a subsequent decrease in cell proliferation. TGF-{beta}1-mediated stimulation of MG63 cells resulted in the increased cell surface expression of HSP90{beta}. Thus, extracellular HSP90{beta} is a negative regulator for the activation of latent TGF-{beta}1 modulating TGF-{beta} signaling in the extracellular domain. -- Research highlights: {yields} Transforming growth factor-beta 1 (TGF-{beta}1) is secreted as a latent complex. {yields} This complex consists of latency-associated peptide (LAP) and the mature ligand. {yields} The release of the mature ligand from LAP is the first step in TGF-{beta} activation. {yields} We identified for the first time a novel mechanism for this activation process. {yields} Heat shock protein 90 {beta} is discovered as a negative regulator for this process.« less

Plasma Membrane Factor XIIIA Transglutaminase Activity Regulates Osteoblast Matrix Secretion and Deposition by Affecting Microtubule Dynamics

PubMed Central

Al-Jallad, Hadil F.; Myneni, Vamsee D.; Piercy-Kotb, Sarah A.; Chabot, Nicolas; Mulani, Amina; Keillor, Jeffrey W.; Kaartinen, Mari T.

2011-01-01

Transglutaminase activity, arising potentially from transglutaminase 2 (TG2) and Factor XIIIA (FXIIIA), has been linked to osteoblast differentiation where it is required for type I collagen and fibronectin matrix deposition. In this study we have used an irreversible TG-inhibitor to ‘block –and-track’ enzyme(s) targeted during osteoblast differentiation. We show that the irreversible TG-inhibitor is highly potent in inhibiting osteoblast differentiation and mineralization and reduces secretion of both fibronectin and type I collagen and their release from the cell surface. Tracking of the dansyl probe by Western blotting and immunofluorescence microscopy demonstrated that the inhibitor targets plasma membrane-associated FXIIIA. TG2 appears not to contribute to crosslinking activity on the osteoblast surface. Inhibition of FXIIIA with NC9 resulted in defective secretory vesicle delivery to the plasma membrane which was attributable to a disorganized microtubule network and decreased microtubule association with the plasma membrane. NC9 inhibition of FXIIIA resulted in destabilization of microtubules as assessed by cellular Glu-tubulin levels. Furthermore, NC9 blocked modification of Glu-tubulin into 150 kDa high-molecular weight Glu-tubulin form which was specifically localized to the plasma membrane. FXIIIA enzyme and its crosslinking activity were colocalized with plasma membrane-associated tubulin, and thus, it appears that FXIIIA crosslinking activity is directed towards stabilizing the interaction of microtubules with the plasma membrane. Our work provides the first mechanistic cues as to how transglutaminase activity could affect protein secretion and matrix deposition in osteoblasts and suggests a novel function for plasma membrane FXIIIA in microtubule dynamics. PMID:21283799

Dynamic responses of concrete-filled steel tubular member under axial compression considering creep effect

NASA Astrophysics Data System (ADS)

Jiang, X. T.; Wang, Y. D.; Dai, C. H.; Ding, M.

2017-08-01

The finite element model of concrete-filled steel tubular member was established by the numerical analysis software considering material nonlinearity to analyze concrete creep effect on the dynamic responses of the member under axial compression and lateral impact. In the model, the constitutive model of core concrete is the plastic damage model, that of steel is the Von Mises yield criterion and kinematic hardening model, and the creep effect at different ages is equivalent to the change of concrete elastic modulus. Then the dynamic responses of concrete-filled steel tubular member considering creep effects was simulated, and the effects of creep on contact time, impact load, deflection, stress and strain were discussed. The fruits provide a scientific basis for the design of the impact resistance of concrete filled steel tubular members.

Development of Na-beta alumina batteries at Pacific Northwest National Laboratory: From tubular to planar

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

Lu, Xiaochuan; Li, Guosheng; Meinhardt, Kerry D.

2016-07-28

Na-beta alumina batteries are one of the most promising technologies for renewable energy storage and grid applications. Na-beta alumina batteries can be constructed in either tubular or planar designs, depending on the shape of the beta-alumina solid electrolyte. The tubular designs have been widely studied and developed since the 1960s primarily because of their ease of sealing. However, planar designs are considered superior to tubular designs in terms of power output, cell packing, ease of assembly, thermal management, and other characteristics. In this paper, we provide an overview on the basic battery electrochemistry, solid electrolyte synthesis and fabrication, battery designs,more » and future trends for further technology improvement.« less

Transepithelial Bicarbonate Secretion: Lessons from the Pancreas

PubMed Central

Park, Hyun Woo; Lee, Min Goo

2012-01-01

Many cystic fibrosis transmembrane conductance regulator (CFTR)-expressing epithelia secrete bicarbonate (HCO3−)-containing fluids. Recent evidence suggests that defects in epithelial bicarbonate secretion are directly involved in the pathogenesis of cystic fibrosis, in particular by building up hyperviscous mucus in the ductal structures of the lung and pancreas. Pancreatic juice is one of the representative fluids that contain a very high concentration of bicarbonate among bodily fluids that are secreted from CFTR-expressing epithelia. We introduce up-to-date knowledge on the basic principles of transepithelial bicarbonate transport by showing the mechanisms involved in pancreatic bicarbonate secretion. The model of pancreatic bicarbonate secretion described herein may also apply to other exocrine epithelia. As a central regulator of bicarbonate transport at the apical membrane, CFTR plays an essential role in both direct and indirect bicarbonate secretion. The major role of CFTR in bicarbonate secretion would be variable depending on the tissue and cell type. For example, in epithelial cells that produce a low concentration of bicarbonate-containing fluid (up to 80 mm), either CFTR-dependent Cl−/HCO3− exchange or CFTR anion channel with low bicarbonate permeability would be sufficient to generate such fluid. However, in cells that secrete high-bicarbonate-containing fluids, a highly selective CFTR bicarbonate channel activity is required. Therefore, understanding the molecular mechanism of transepithelial bicarbonate transport and the role of CFTR in each specific epithelium will provide therapeutic strategies to recover from epithelial defects induced by hyposecretion of bicarbonate in cystic fibrosis. PMID:23028131

Substrate adaptation of Trichophyton rubrum secreted endoproteases.

PubMed

Chen, Jian; Yi, Jinling; Liu, Li; Yin, Songchao; Chen, Rongzhang; Li, Meirong; Ye, Congxiu; Zhang, Yu-qing; Lai, Wei

2010-02-01

Trichophyton rubrum is the most common pathogen caused the dermatophytosis of nail and skin in human. The secreted proteases were considered to be the most important virulence factors. However, the substrates adaptation of T. rubrum secreted proteases is largely unknown. For the first time, we use the keratins from human nail and skin stratum corneum as the growth medium to investigate the different expression patterns of T. rubrum secreted endoproteases genes. During grow in both keratin-containing media SUB7 and MEP2 were the highest expressed gene in each family. These results indicated that SUB7 and MEP2 may be the dominant endoproteases secreted by T. rubrum during host infection and the other proteases may play a supplementary role. The direct comparison of T. rubrum grown on skin and nail medium showed different substrate favorite of secreted endoproteases. The genes MEP2, SUB5, SUB2 and SUB3 were more active during growth in skin medium, possibly these proteases have a higher affinity for skin original keratins. While the structures of SUB1, SUB4, and MEP4 maybe more suitable for the degradation of nail original keratins. This work presents useful molecular details for further understanding the pathogenesis of secreted proteases and the wide adaptation of T. rubrum.

Distal Renal Tubular Acidosis in Infancy: A Bicarbonate Wasting State

ERIC Educational Resources Information Center

Rodriguez-Soriano, J.; And Others

1975-01-01

Studied were three unrelated infants with distal renal tubular acidosis (a condition characterized by an inability to acidify the urine to minimal pH levels resulting in the loss of bicarbonates). (DB)

Rocket-inspired tubular catalytic microjets with grating-structured walls as guiding empennages.

PubMed

Huang, Gaoshan; Wang, Jiyuan; Liu, Zhaoqian; Zhou, Dekai; Tian, Ziao; Xu, Borui; Li, Longqiu; Mei, Yongfeng

2017-12-07

Controllable locomotion in the micro-/nanoscale is challenging and attracts increasing research interest. Tubular microjets self-propelled by microbubbles are intensively investigated due to their high energy conversion efficiency, but the imperfection of the tubular geometry makes it harder to realize linear motion. Inspired by the macro rocket, we designed a tubular microjet with a grating-structured wall which mimics the guiding empennage of the macro rocket, and we found that the fluid can be effectively guided by the grooves. Both theoretical simulation and experimental work have been carried out, and the obtained results demonstrate that the stability margin of the grating-structured microjet can be enhanced. Compared with microjets with smooth walls, the structured microjets show an enhanced ability of moving linearly. In 10% H 2 O 2 , only 20% of the smooth microjets demonstrate linear trajectories, while 80% of the grating-structured microjets keep moving straight. The grating-structured microjet can maintain linear motion under external disturbance. We further propose to increase the stability by introducing a helical grating structure.

Differentiation of vasoactive renal sympathetic nerve fibres.

PubMed

Dibona, G F

2000-01-01

Activation of renal sympathetic nerves produces marked changes in renal haemodynamics, tubular ion and water transport and renin secretion. This review examines information indicating that these effects are mediated by functionally specific groups of renal sympathetic nerve fibres separately innervating the renal vessels, tubules and juxtaglomerular granular cells.

Tubular system volume changes in twitch fibres from toad and rat skeletal muscle assessed by confocal microscopy

PubMed Central

Launikonis, Bradley S; Stephenson, D George

2002-01-01

The volume of the extracellular compartment (tubular system) within intact muscle fibres from cane toad and rat was measured under various conditions using confocal microscopy. Under physiological conditions at rest, the fractional volume of the tubular system (t-sysVol) was 1.38 ± 0.09 % (n = 17), 1.41 ± 0.09 % (n = 12) and 0.83 ± 0.07 % (n = 12) of the total fibre volume in the twitch fibres from toad iliofibularis muscle, rat extensor digitorum longus muscle and rat soleus muscle, respectively. In toad muscle fibres, the t-sysVol decreased by 30 % when the tubular system was fully depolarized and decreased by 15 % when membrane cholesterol was depleted from the tubular system with methyl-β-cyclodextrin but did not change as the sarcomere length was changed from 1.93 to 3.30 μm. There was also an increase by 30 % and a decrease by 25 % in t-sysVol when toad fibres were equilibrated in solutions that were 2.5-fold hypertonic and 50 % hypotonic, respectively. When the changes in total fibre volume were taken into consideration, the t-sysVol expressed as a percentage of the isotonic fibre volume did actually decrease as tonicity increased, revealing that the tubular system in intact fibres cannot be compressed below 0.9 % of the isotonic fibre volume. The results can be explained in terms of forces acting at the level of the tubular wall. These observations have important physiological implications showing that the tubular system is a dynamic membrane structure capable of changing its volume in response to the membrane potential, cholesterol depletion and osmotic stress but not when the sarcomere length is changed in resting muscle. PMID:11790823

Visualization of glucagon secretion from pancreatic α cells by bioluminescence video microscopy: Identification of secretion sites in the intercellular contact regions

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

Yokawa, Satoru; School of Pharmacy, Aichi Gakuin University, Nagoya 464-8650; Suzuki, Takahiro

We have firstly visualized glucagon secretion using a method of video-rate bioluminescence imaging. The fusion protein of proglucagon and Gaussia luciferase (PGCG-GLase) was used as a reporter to detect glucagon secretion and was efficiently expressed in mouse pancreatic α cells (αTC1.6) using a preferred human codon-optimized gene. In the culture medium of the cells expressing PGCG-GLase, luminescence activity determined with a luminometer was increased with low glucose stimulation and KCl-induced depolarization, as observed for glucagon secretion. From immunochemical analyses, PGCG-GLase stably expressed in clonal αTC1.6 cells was correctly processed and released by secretory granules. Luminescence signals of the secreted PGCG-GLase frommore » the stable cells were visualized by video-rate bioluminescence microscopy. The video images showed an increase in glucagon secretion from clustered cells in response to stimulation by KCl. The secretory events were observed frequently at the intercellular contact regions. Thus, the localization and frequency of glucagon secretion might be regulated by cell-cell adhesion. - Highlights: • The fused protein of proglucagon to Gaussia luciferase was used as a reporter. • The fusion protein was highly expressed using a preferred human-codon optimized gene. • Glucagon secretion stimulated by depolarization was determined by luminescence. • Glucagon secretion in α cells was visualized by bioluminescence imaging. • Glucagon secretion sites were localized in the intercellular contact regions.« less

Proteomic Identification of Novel Secreted Antibacterial Toxins of the Serratia marcescens Type VI Secretion System*

PubMed Central

Fritsch, Maximilian J.; Trunk, Katharina; Diniz, Juliana Alcoforado; Guo, Manman; Trost, Matthias; Coulthurst, Sarah J.

2013-01-01

It has recently become apparent that the Type VI secretion system (T6SS) is a complex macromolecular machine used by many bacterial species to inject effector proteins into eukaryotic or bacterial cells, with significant implications for virulence and interbacterial competition. “Antibacterial” T6SSs, such as the one elaborated by the opportunistic human pathogen, Serratia marcescens, confer on the secreting bacterium the ability to rapidly and efficiently kill rival bacteria. Identification of secreted substrates of the T6SS is critical to understanding its role and ability to kill other cells, but only a limited number of effectors have been reported so far. Here we report the successful use of label-free quantitative mass spectrometry to identify at least eleven substrates of the S. marcescens T6SS, including four novel effector proteins which are distinct from other T6SS-secreted proteins reported to date. These new effectors were confirmed as antibacterial toxins and self-protecting immunity proteins able to neutralize their cognate toxins were identified. The global secretomic study also unexpectedly revealed that protein phosphorylation-based post-translational regulation of the S. marcescens T6SS differs from that of the paradigm, H1-T6SS of Pseudomonas aeruginosa. Combined phosphoproteomic and genetic analyses demonstrated that conserved PpkA-dependent threonine phosphorylation of the T6SS structural component Fha is required for T6SS activation in S. marcescens and that the phosphatase PppA can reverse this modification. However, the signal and mechanism of PpkA activation is distinct from that observed previously and does not appear to require cell–cell contact. Hence this study has not only demonstrated that new and species-specific portfolios of antibacterial effectors are secreted by the T6SS, but also shown for the first time that PpkA-dependent post-translational regulation of the T6SS is tailored to fit the needs of different bacterial

Molecular Mechanism of Pancreatic and Salivary Glands Fluid and HCO3− Secretion

PubMed Central

Lee, Min Goo; Ohana, Ehud; Park, Hyun Woo; Yang, Dongki; Muallem, Shmuel

2013-01-01

Fluid and HCO3− secretion is a vital function of all epithelia and is required for the survival of the tissue. Aberrant fluid and HCO3− secretion is associated with many epithelial diseases, such as cystic fibrosis, pancreatitis, Sjögren’s syndrome and other epithelial inflammatory and autoimmune diseases. Significant progress has been made over the last 20 years in our understanding of epithelial fluid and HCO3− secretion, in particular by secretory glands. Fluid and HCO3− secretion by secretory glands is a two step process. Acinar cells secrete isotonic fluid in which the major salt is NaCl. Subsequently, the duct modifies the volume and electrolyte composition of the fluid to absorb the Cl− and secrete HCO3−. The relative volume secreted by acinar and duct cells and modification of electrolyte composition of the secreted fluids varies among secretory glands to meet their physiological functions. In the pancreas, acinar cells secrete small amount of NaCl-rich fluid, while the duct absorbs the Cl− and secretes HCO3− and the bulk of the fluid in the pancreatic juice. Fluid secretion appears to be driven by active HCO3− secretion. In the salivary glands, acinar cells secrete the bulk of the fluid in the saliva that contains high concentrations of Na+ and Cl− and fluid secretion is mediated by active Cl− secretion. The salivary glands duct absorbs both the Na+ and Cl− and secretes K+ and HCO3−. In this review, we focus on the molecular mechanism of fluid and HCO3− secretion by the pancreas and salivary glands, to highlight the similarities of the fundamental mechanisms of acinar and duct cell functions, and point the differences to meet glands specific secretions. PMID:22298651

Secretion of the Streptomyces tyrosinase is mediated through its trans-activator protein, MelC1.

PubMed

Leu, W M; Chen, L Y; Liaw, L L; Lee, Y H

1992-10-05

The tyrosinase of Streptomyces antibioticus is encoded by the second open reading frame, melC2 of the melanin operon (melC). The upstream open reading frame melC1 specifies a 146-amino acid protein with a typical NH2-terminal signal-peptide characteristic of a secretory protein. The MelC1 protein is involved in the transfer of copper ion to apotyrosinase MelC2 via binary complex formation (Lee, Y.-H. W., Chen, B.-F., Wu, S.-Y., Leu, W.-M., Lin, J.-J., Chen, C. W., and Lo, S. J. (1988) Gene (Amst.) 65, 71-81; Chen, L.-Y., Leu, W.-M., Wang, K.-T., and Lee, Y.-H.W. (1992) J. Biol. Chem. 267, 20100-20107). To investigate whether the export of tyrosinase is also dependent on MelC1, a mutational study of its signal-peptide sequence was performed. Four different mutants were obtained. Mutation at the positively charged region (mutant M-6LE, Arg6-Arg7----Leu6-Glu7) or the hydrophobic region (mutant M-16D, Val16----Asp16) led to Mel- phenotypes. These lesions caused a severe 7-10-fold reduction of the export of both the MelC1 and MelC2 proteins and a concomitant accumulation of the two proteins in the cytosolic fraction. The cell-associated tyrosinase activity in M-6LE but not in the M-16D mutant was dramatically reduced to 4% of the activity found in the wild type strain, suggesting that the basic NH2 terminus of MelC1 is also important for the trans-activation function of this protein. Nevertheless, the defects on the trans-activation and/or secretory functions of MelC1 in mutants M-6LE and M-16D are not due to the impairment of the formation of the MelC1.MelC2 complex. The translation of melanin operon genes in these two mutants also decreased. In contrast, the tyrosinase activity and the secretion of MelC2 were not affected if the mutations occurred at the putative cleavage site of the signal peptidase (e.g. mutant M-29SM, Arg29-Ala30----Ser29-Met30 or mutant 29-SMG, Arg29-Ala30-Asp31----Ser29-Med30-Gly31+ ++). Additionally, tyrosinase activity and its export were

[Drugs inhibiting parathyroid hormone (PTH) secretion by control of the calcium receptor (calcimimetics)--effect on the set point of calcium-regulated PTH secretion].

PubMed

Nagano, Nobuo

2005-01-01

Calcimimetics are positive allosteric modulators that activate the parathyroid calcium receptor (CaR) and thereby immediately suppress parathyroid hormone (PTH) secretion. Preclinical studies have demonstrated that calcimimetics inhibit PTH secretion and parathyroid gland hyperplasia and ameliorates bone qualities in rats with chronic renal insufficiency. Clinical trials with cinacalcet hydrochloride, a calcimimetic compound, have shown that calcimimetics possess lowering effects not only on serum PTH levels but also on serum phosphorus levels in dialysis patients with secondary hyperparathyroidism (2HPT). Thus, calcimimetics have considerable potential as an innovative medical approach to manage 2HPT. In this review, the similarities are extrapolated between the pharmacological effect of calcimimetics on the set point of Ca-regulated PTH secretion and clinical observations in affected subjects with activating CaR mutations.

Engineering tubular bone using mesenchymal stem cell sheets and coral particles

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

Geng, Wenxin; Ma, Dongyang; Yan, Xingrong

Highlights: • We developed a novel engineering strategy to solve the limitations of bone grafts. • We fabricated tubular constructs using cell sheets and coral particles. • The composite constructs showed high radiological density and compressive strength. • These characteristics were similar to those of native bone. -- Abstract: The development of bone tissue engineering has provided new solutions for bone defects. However, the cell-scaffold-based approaches currently in use have several limitations, including low cell seeding rates and poor bone formation capacity. In the present study, we developed a novel strategy to engineer bone grafts using mesenchymal stem cell sheetsmore » and coral particles. Rabbit bone marrow mesenchymal stem cells were continuously cultured to form a cell sheet with osteogenic potential and coral particles were integrated into the sheet. The composite sheet was then wrapped around a cylindrical mandrel to fabricate a tubular construct. The resultant tubular construct was cultured in a spinner-flask bioreactor and subsequently implanted into a subcutaneous pocket in a nude mouse for assessment of its histological characteristics, radiological density and mechanical property. A similar construct assembled from a cell sheet alone acted as a control. In vitro observations demonstrated that the composite construct maintained its tubular shape, and exhibited higher radiological density, compressive strength and greater extracellular matrix deposition than did the control construct. In vivo experiments further revealed that new bone formed ectopically on the composite constructs, so that the 8-week explants of the composite sheets displayed radiological density similar to that of native bone. These results indicate that the strategy of using a combination of a cell sheet and coral particles has great potential for bone tissue engineering and repairing bone defects.« less

Non-Cationic Proteins Are Associated with HIV Neutralizing Activity in Genital Secretions of Female Sex Workers.

PubMed

Birse, Kenzie D M; Cole, Amy L; Hirbod, Taha; McKinnon, Lyle; Ball, Terry B; Westmacott, Garrett R; Kimani, Joshua; Plummer, Frank; Cole, Alexander M; Burgener, Adam; Broliden, Kristina

2015-01-01

Cationic proteins found in cervicovaginal secretions (CVS) are known to contribute to the early antiviral immune response against HIV-infection in vitro. We here aimed to define additional antiviral factors that are over-expressed in CVS from female sex workers at high risk of infection. CVS were collected from Kenyan HIV-seronegative (n = 34) and HIV-seropositive (n = 12) female sex workers, and were compared with those from HIV-seronegative low-risk women (n = 12). The highly exposed seronegative (HESN) sex workers were further divided into those with less (n = 22) or more (n = 12) than three years of documented sex work. Cationic protein-depleted CVS were assessed for HIV-neutralizing activity by a PBMC-based HIV-neutralizing assay, and then characterized by proteomics. HIV neutralizing activity was detected in all unprocessed CVS, however only CVS from the female sex worker groups maintained its HIV neutralizing activity after cationic protein-depletion. Differentially abundant proteins were identified in the cationic protein-depleted secretions including 26, 42, and 11 in the HESN>3 yr, HESN<3 yr, and HIV-positive groups, respectively. Gene ontology placed these proteins into functional categories including proteolysis, oxidation-reduction, and epidermal development. The proteins identified in this study include proteins previously associated with the HESN phenotype in other cohorts as well as novel proteins not yet associated with anti-HIV activities. While cationic proteins appear to contribute to the majority of the intrinsic HIV neutralizing activity in the CVS of low-risk women, a broader range of non-cationic proteins were associated with HIV neutralizing activity in HESN and HIV-positive female sex workers. These results indicate that novel protein factors found in CVS of women with high-risk sexual practices may have inherent antiviral activity, or are involved in other aspects of anti-HIV host defense, and warrant further exploration into their mode

A gatekeeper chaperone complex directs translocator secretion during Type Three Secretion

DOE PAGES

Archuleta, Tara L.; Spiller, Benjamin W.; Kubori, Tomoko

2014-11-06

Many Gram-negative bacteria use Type Three Secretion Systems (T3SS) to deliver effector proteins into host cells. These protein delivery machines are composed of cytosolic components that recognize substrates and generate the force needed for translocation, the secretion conduit, formed by a needle complex and associated membrane spanning basal body, and translocators that form the pore in the target cell. A defined order of secretion in which needle component proteins are secreted first, followed by translocators, and finally effectors, is necessary for this system to be effective. While the secreted effectors vary significantly between organisms, the ~20 individual protein components thatmore » form the T3SS are conserved in many pathogenic bacteria. One such conserved protein, referred to as either a plug or gatekeeper, is necessary to prevent unregulated effector release and to allow efficient translocator secretion. The mechanism by which translocator secretion is promoted while effector release is inhibited by gatekeepers is unknown. We present the structure of the Chlamydial gatekeeper, CopN, bound to a translocator-specific chaperone. The structure identifies a previously unknown interface between gatekeepers and translocator chaperones and reveals that in the gatekeeper-chaperone complex the canonical translocator-binding groove is free to bind translocators. Thus, structure-based mutagenesis of the homologous complex in Shigella reveals that the gatekeeper-chaperone-translocator complex is essential for translocator secretion and for the ordered secretion of translocators prior to effectors.« less

Wrapped up in Covers: Preschoolers' Secrets and Secret Hiding Places

ERIC Educational Resources Information Center

Corson, Kimberly; Colwell, Malinda J.; Bell, Nancy J.; Trejos-Castillo, Elizabeth

2014-01-01

In this qualitative study, interviews about children's secret hiding places were conducted with 3-5-year-olds (n?=?17) in a university sponsored preschool programme using art narratives. Since prior studies indicate that children understand the concept of a secret as early as five and that they associate secrets with hiding places, the purpose of…

Economic Analysis of Anatomic Plating Versus Tubular Plating for the Treatment of Fibula Fractures.

PubMed

Chang, Gerard; Bhat, Suneel B; Raikin, Steven M; Kane, Justin M; Kay, Andrew; Ahmad, Jamal; Pedowitz, David I; Krieg, James

2018-03-01

Ankle fractures are among the most common injuries requiring operative management. Implant choices include one-third tubular plates and anatomically precontoured plates. Although cadaveric studies have not revealed biomechanical differences between various plate constructs, there are substantial cost differences. This study sought to characterize the economic implications of implant choice. A retrospective review was undertaken of 201 consecutive patients with operatively treated OTA type 44B and 44C ankles. A Nationwide Inpatient Sample query was performed to estimate the incidence of ankle fractures requiring fibular plating, and a Monte Carlo simulation was conducted with the estimated at-risk US population for associated plate-specific costs. The authors estimated an annual incidence of operatively treated ankle fractures in the United States of 59,029. The average cost was $90.86 (95% confidence interval, $90.84-$90.87) for a one-third tubular plate vs $746.97 (95% confidence interval, $746.55-$747.39) for an anatomic plate. Across the United States, use of only one-third tubular plating over anatomic plating would result in statistically significant savings of $38,729,517 (95% confidence interval, $38,704,773-$38,754,261; P<.0001). General use of one-third tubular plating instead of anatomic plating whenever possible for fibula fractures could result in cost savings of up to nearly $40 million annually in the United States. Unless clinically justifiable on a per-case basis, or until the advent of studies showing substantial clinical benefit, there currently is no reason for the increased expense from widespread use of anatomic plating for fractures amenable to one-third tubular plating. [Orthopedics. 2018; 41(2):e252-e256.]. Copyright 2018, SLACK Incorporated.

Micro-tubular solid oxide fuel cell based on a porous yttria-stabilized zirconia support

NASA Astrophysics Data System (ADS)

Panthi, Dhruba; Tsutsumi, Atsushi

2014-08-01

Solid oxide fuel cells (SOFCs) are promising electrochemical energy conversion devices owing to their high power generation efficiency and environmentally benign operation. Micro-tubular SOFCs, which have diameters ranging from a few millimeters to the sub-millimeter scale, offer several advantages over competing SOFCs such as high volumetric power density, good endurance against thermal cycling, and flexible sealing between fuel and oxidant streams. Herein, we successfully realized a novel micro-tubular SOFC design based on a porous yttria-stabilized zirconia (YSZ) support using multi-step dip coating and co-sintering methods. The micro-tubular SOFC consisted of Ni-YSZ, YSZ, and strontium-doped lanthanum manganite (LSM)-YSZ as the anode, electrolyte, and cathode, respectively. In addition, to facilitate current collection from the anode and cathode, Ni and LSM were applied as an anode current collector and cathode current collector, respectively. Micro-crystalline cellulose was selected as a pore former to achieve better shrinkage behavior of the YSZ support so that the electrolyte layer could be densified at a co-sintering temperature of 1300°C. The developed micro-tubular design showed a promising electrochemical performance with maximum power densities of 525, 442, and 354 mW cm-2 at 850, 800, and 750°C, respectively.

A narrow open tubular column for high efficiency liquid chromatographic separation.

PubMed

Chen, Huang; Yang, Yu; Qiao, Zhenzhen; Xiang, Piliang; Ren, Jiangtao; Meng, Yunzhu; Zhang, Kaiqi; Juan Lu, Joann; Liu, Shaorong

2018-04-30

We report a great feature of open tubular liquid chromatography when it is run using an extremely narrow (e.g., 2 μm inner diameter) open tubular column: more than 10 million plates per meter can be achieved in less than 10 min and under an elution pressure of ca. 20 bar. The column is coated with octadecylsilane and both isocratic and gradient separations are performed. We reveal a focusing effect that may be used to interpret the efficiency enhancement. We also demonstrate the feasibility of using this technique for separating complex peptide samples. This high-resolution and fast separation technique is promising and can lead to a powerful tool for trace sample analysis.

Acquired Fanconi syndrome with proximal tubular cytoplasmic fibrillary inclusions of λ light chain restriction.

PubMed

Yao, Ying; Wang, Su-Xia; Zhang, You-Kang; Wang, Yan; Liu, Li; Liu, Gang

2014-01-01

Light chain proximal tubulopathy is a rarely reported entity associated with plasma cell dyscrasia that classically manifests as acquired Fanconi syndrome and is characterized by the presence of κ-restricted crystals in the proximal tubular cytoplasm. We herein present a case of multiple myeloma with Fanconi syndrome and acute kidney injury due to light chain proximal tubulopathy with light chain cast nephropathy. Prominent phagolysosomes and numerous irregularly shaped inclusions with a fibrillary matrix in the cytoplasm of the proximal tubules were identified on electron microscopy. A monotypic light chain of the λ type was detected in the distal tubular casts, proximal tubular cytoplasmic lysosomes and fibrillary inclusions on immunofluorescence and immune electron microscopy. This case underscores the importance of conducting careful ultrastructural investigations and immunocytologic examinations of light chains for detecting and diagnosing light chain proximal tubulopathy.

Vibrio parahaemolyticus Type VI Secretion System 1 Is Activated in Marine Conditions to Target Bacteria, and Is Differentially Regulated from System 2

PubMed Central

Salomon, Dor; Gonzalez, Herman; Updegraff, Barrett L.; Orth, Kim

2013-01-01

Vibrio parahaemolyticus is a marine bacterium that thrives in warm climates. It is a leading cause of gastroenteritis resulting from consumption of contaminated uncooked shellfish. This bacterium harbors two putative type VI secretion systems (T6SS). T6SSs are widespread protein secretion systems found in many Gram-negative bacteria, and are often tightly regulated. For many T6SSs studied to date, the conditions and cues, as well as the regulatory mechanisms that control T6SS activity are unknown. In this study, we characterized the environmental conditions and cues that activate both V. parahaemolyticus T6SSs, and identified regulatory mechanisms that control T6SS gene expression and activity. We monitored the expression and secretion of the signature T6SS secreted proteins Hcp1 and Hcp2, and found that both T6SSs are differentially regulated by quorum sensing and surface sensing. We also showed that T6SS1 and T6SS2 require different temperature and salinity conditions to be active. Interestingly, T6SS1, which is found predominantly in clinical isolates, was most active under warm marine-like conditions. Moreover, we found that T6SS1 has anti-bacterial activity under these conditions. In addition, we identified two transcription regulators in the T6SS1 gene cluster that regulate Hcp1 expression, but are not required for immunity against self-intoxication. Further examination of environmental isolates revealed a correlation between the presence of T6SS1 and virulence of V. parahaemolyticus against other bacteria, and we also showed that different V. parahaemolyticus isolates can outcompete each other. We propose that T6SS1 and T6SS2 play different roles in the V. parahaemolyticus lifestyles, and suggest a role for T6SS1 in enhancing environmental fitness of V. parahaemolyticus in marine environments when competing for a niche in the presence of other bacterial populations. PMID:23613791