Science.gov

Sample records for proximal nhe3 promoter

  1. Dopamine D3 receptor inhibits the ubiquitin-specific peptidase 48 to promote NHE3 degradation

    PubMed Central

    Armando, Ines; Villar, Van Anthony M.; Jones, John E.; Lee, Hewang; Wang, Xiaoyan; Asico, Laureano D.; Yu, Peiying; Yang, Jian; Escano, Crisanto S.; Pascua-Crusan, Annabelle M.; Felder, Robin A.; Jose, Pedro A.

    2014-01-01

    The dopamine D3 receptor (D3R) is crucial in the regulation of blood pressure and sodium balance, in that Drd3 gene ablation in mice results in hypertension and failure to excrete a dietary salt load. The mechanism responsible for the renal sodium retention in these mice is largely unknown. We now offer and describe a novel mechanism by which D3R decreases sodium transport in the long term by inhibiting the deubiquitinylating activity of ubiquitin-specific peptidase 48 (USP48), thereby promoting Na+-H+ exchanger (NHE)-3 degradation. We found that stimulation with the D3R-specific agonist PD128907 (1 μM, 30 min) promoted the interaction and colocalization among D3R, NHE3, and USP48; inhibited USP48 activity (−35±6%, vs. vehicle), resulting in increased ubiquitinylated NHE3 (+140±10%); and decreased NHE3 expression (−50±9%) in human renal proximal tubule cells (hRPTCs). USP48 silencing decreased NHE3's half-life (USP48 siRNA t1/2=6.1 h vs. vehicle t1/2=12.9 h), whereas overexpression of USP48 increased NHE3 half-life (t1/2=21.8 h), indicating that USP48 protects NHE3 from degradation via deubiquitinylation. USP48 accounted for ∼30% of the total deubiquitinylating activity in these cells. Extending our studies in vivo, we found that pharmacologic blockade of D3R via the D3R-specific antagonist GR103691 (1 μg/kg/min, 4 d) in C57Bl/6J mice increased renal NHE3 expression (+310±15%, vs. vehicle), whereas an innovative kidney-restricted Usp48 silencing via siRNA (3 μg/d, 7 d) increased ubiquitinylated NHE3 (+250±30%, vs. controls), decreased total NHE3 (−23±2%), and lowered blood pressure (−24±2 mm Hg), compared with that in control mice that received either the vehicle or nonsilencing siRNA. Our data demonstrate a crucial role for the dynamic interaction between D3R and USP48 in the regulation of NHE3 expression and function.—Armando, I., Villar, V. A. M., Jones J. E., Lee, H., Wang, X., Asico L. D., Yu, P., Yang, J., Escano, C. S. Jr., Pascua

  2. Transcriptional regulation of NHE3 and SGLT1 by the circadian clock protein Per1 in proximal tubule cells.

    PubMed

    Solocinski, Kristen; Richards, Jacob; All, Sean; Cheng, Kit-Yan; Khundmiri, Syed J; Gumz, Michelle L

    2015-12-01

    We have previously demonstrated that the circadian clock protein period (Per)1 coordinately regulates multiple genes involved in Na(+) reabsorption in renal collecting duct cells. Consistent with these results, Per1 knockout mice exhibit dramatically lower blood pressure than wild-type mice. The proximal tubule is responsible for a majority of Na(+) reabsorption. Previous work has demonstrated that expression of Na(+)/H(+) exchanger 3 (NHE3) oscillates with a circadian pattern and Na(+)-glucose cotransporter (SGLT)1 has been demonstrated to be a circadian target in the colon, but whether these target genes are regulated by Per1 has not been investigated in the kidney. The goal of the present study was to determine if Per1 regulates the expression of NHE3, SGLT1, and SGLT2 in the kidney. Pharmacological blockade of nuclear Per1 entry resulted in decreased mRNA expression of SGLT1 and NHE3 but not SGLT2 in the renal cortex of mice. Per1 small interfering RNA and pharmacological blockade of Per1 nuclear entry in human proximal tubule HK-2 cells yielded the same results. Examination of heterogeneous nuclear RNA suggested that the effects of Per1 on NHE3 and SGLT1 expression occurred at the level of transcription. Per1 and the circadian protein CLOCK were detected at promoters of NHE3 and SGLT1. Importantly, both membrane and intracellular protein levels of NHE3 and SGLT1 were decreased after blockade of nuclear Per1 entry. This effect was associated with reduced activity of Na(+)-K(+)-ATPase. These data demonstrate a role for Per1 in the transcriptional regulation of NHE3 and SGLT1 in the kidney. PMID:26377793

  3. Proximal tubule NHE3 activity is inhibited by beta-arrestin-biased angiotensin II type 1 receptor signaling.

    PubMed

    Carneiro de Morais, Carla P; Polidoro, Juliano Z; Ralph, Donna L; Pessoa, Thaissa D; Oliveira-Souza, Maria; Barauna, Valério G; Rebouças, Nancy A; Malnic, Gerhard; McDonough, Alicia A; Girardi, Adriana C C

    2015-10-15

    Physiological concentrations of angiotensin II (ANG II) upregulate the activity of Na(+)/H(+) exchanger isoform 3 (NHE3) in the renal proximal tubule through activation of the ANG II type I (AT1) receptor/G protein-coupled signaling. This effect is key for maintenance of extracellular fluid volume homeostasis and blood pressure. Recent findings have shown that selective activation of the beta-arrestin-biased AT1 receptor signaling pathway induces diuresis and natriuresis independent of G protein-mediated signaling. This study tested the hypothesis that activation of this AT1 receptor/beta-arrestin signaling inhibits NHE3 activity in proximal tubule. To this end, we determined the effects of the compound TRV120023, which binds to the AT1R, blocks G-protein coupling, and stimulates beta-arrestin signaling on NHE3 function in vivo and in vitro. NHE3 activity was measured in both native proximal tubules, by stationary microperfusion, and in opossum proximal tubule (OKP) cells, by Na(+)-dependent intracellular pH recovery. We found that 10(-7) M TRV120023 remarkably inhibited proximal tubule NHE3 activity both in vivo and in vitro. Additionally, stimulation of NHE3 by ANG II was completely suppressed by TRV120023 both in vivo as well as in vitro. Inhibition of NHE3 activity by TRV120023 was associated with a decrease in NHE3 surface expression in OKP cells and with a redistribution from the body to the base of the microvilli in the rat proximal tubule. These findings indicate that biased signaling of the beta-arrestin pathway through the AT1 receptor inhibits NHE3 activity in the proximal tubule at least in part due to changes in NHE3 subcellular localization. PMID:26246427

  4. Endothelin-1/endothelin-B receptor–mediated increases in NHE3 activity in chronic metabolic acidosis

    PubMed Central

    Laghmani, Kamel; Preisig, Patricia A.; Moe, Orson W.; Yanagisawa, Masashi; Alpern, Robert J.

    2001-01-01

    Decreases in blood pH activate NHE3, the proximal tubular apical membrane Na/H antiporter. In cultured renal epithelial cells, activation of the endothelin-B (ETB) receptor increases NHE3 activity. To examine the role of the ETB receptor in the response to acidosis in vivo, the present studies examined ETB receptor–deficient mice, rescued from neonatal lethality by expression of a dopamine β-hydroxylase promoter/ETB receptor transgene (Tg/Tg:ETB–/– mice). In proximal tubule suspensions from Tg/Tg:ETB+/– mice, 10–8 M endothelin-1 (ET-1) increased NHE3 activity, but this treatment had no effect on tubules from Tg/Tg:ETB–/– mice. Acid ingestion for 7 days caused a greater decrease in blood HCO3– concentration in Tg/Tg:ETB–/– mice compared with Tg/Tg:ETB+/+ and Tg/Tg:ETB+/– mice. Whereas acid ingestion increased apical membrane NHE3 by 42–46% in Tg/Tg:ETB+/+ and Tg/Tg:ETB+/– mice, it had no effect on NHE3 in Tg/Tg:ETB–/– mice. In C57BL/6 mice, excess acid ingestion increased renal cortical preproET-1 mRNA expression 2.4-fold and decreased preproET-3 mRNA expression by 37%. On a control diet, Tg/Tg:ETB–/– mice had low rates of ammonium excretion, which could not be attributed to an inability to acidify the urine, as well as hypercitraturia, with increased titratable acid excretion. Acid ingestion increased ammonium excretion, citrate absorption, and titratable acid excretion to the same levels in Tg/Tg:ETB–/– and Tg/Tg:ETB+/+ mice. In conclusion, metabolic acidosis increases ET-1 expression, which increases NHE3 activity via the ETB receptor. PMID:11413164

  5. Carbonic anhydrase II binds to and increases the activity of the epithelial sodium-proton exchanger, NHE3.

    PubMed

    Krishnan, Devishree; Liu, Lei; Wiebe, Shane A; Casey, Joseph R; Cordat, Emmanuelle; Alexander, R Todd

    2015-08-15

    Two-thirds of sodium filtered by the renal glomerulus is reabsorbed from the proximal tubule via a sodium/proton exchanger isoform 3 (NHE3)-dependent mechanism. Since sodium and bicarbonate reabsorption are coupled, we postulated that the molecules involved in their reabsorption [NHE3 and carbonic anhydrase II (CAII)] might physically and functionally interact. Consistent with this, CAII and NHE3 were closely associated in a renal proximal tubular cell culture model as revealed by a proximity ligation assay. Direct physical interaction was confirmed in solid-phase binding assays with immobilized CAII and C-terminal NHE3 glutathione-S-transferase fusion constructs. To assess the effect of CAII on NHE3 function, we expressed NHE3 in a proximal tubule cell line and measured NHE3 activity as the rate of intracellular pH recovery, following an acid load. NHE3-expressing cells had a significantly greater rate of intracellular pH recovery than controls. Inhibition of endogenous CAII activity with acetazolamide significantly decreased NHE3 activity, indicating that CAII activates NHE3. To ascertain whether CAII binding per se activates NHE3, we expressed NHE3 with wild-type CAII, a catalytically inactive CAII mutant (CAII-V143Y), or a mutant unable to bind other transporters (CAII-HEX). NHE3 activity increased upon wild-type CAII coexpression, but not in the presence of the CAII V143Y or HEX mutant. Together these studies support an association between CAII and NHE3 that alters the transporter's activity. PMID:26041446

  6. Carbonic anhydrase II binds to and increases the activity of the epithelial sodium-proton exchanger, NHE3

    PubMed Central

    Krishnan, Devishree; Liu, Lei; Wiebe, Shane A.; Casey, Joseph R.; Cordat, Emmanuelle; Alexander, R. Todd

    2016-01-01

    Two-thirds of sodium filtered by the renal glomerulus is reabsorbed from the proximal tubule via a sodium/proton exchanger isoform 3 (NHE3)-dependent mechanism. Since sodium and bicarbonate reabsorption are coupled, we postulated that the molecules involved in their reabsorption [NHE3 and carbonic anhydrase II (CAII)] might physically and functionally interact. Consistent with this, CAII and NHE3 were closely associated in a renal proximal tubular cell culture model as revealed by a proximity ligation assay. Direct physical interaction was confirmed in solid-phase binding assays with immobilized CAII and C-terminal NHE3 glutathione-S-transferase fusion constructs. To assess the effect of CAII on NHE3 function, we expressed NHE3 in a proximal tubule cell line and measured NHE3 activity as the rate of intracellular pH recovery, following an acid load. NHE3-expressing cells had a significantly greater rate of intracellular pH recovery than controls. Inhibition of endogenous CAII activity with acetazolamide significantly decreased NHE3 activity, indicating that CAII activates NHE3. To ascertain whether CAII binding per se activates NHE3, we expressed NHE3 with wild-type CAII, a catalytically inactive CAII mutant (CAII-V143Y), or a mutant unable to bind other transporters (CAII-HEX). NHE3 activity increased upon wild-type CAII coexpression, but not in the presence of the CAII V143Y or HEX mutant. Together these studies support an association between CAII and NHE3 that alters the transporter’s activity. PMID:26041446

  7. Lactobacillus acidophilus upregulates intestinal NHE3 expression and function

    PubMed Central

    Singh, Varsha; Raheja, Geetu; Borthakur, Alip; Kumar, Anoop; Gill, Ravinder K.; Alakkam, Anas; Malakooti, Jaleh

    2012-01-01

    A major mechanism of electroneutral NaCl absorption in the human ileum and colon involves coupling of Na+/H+ and Cl−/HCO3− exchangers. Disturbances in these mechanisms have been implicated in diarrheal conditions. Probiotics such as Lactobacillus have been indicated to be beneficial in the management of gastrointestinal disorders, including diarrhea. However, the molecular mechanisms underlying antidiarrheal effects of probiotics have not been fully understood. We have previously demonstrated Lactobacillus acidophilus (LA) to stimulate Cl−/HCO3− exchange activity via an increase in the surface levels and expression of the Cl−/HCO3− exchanger DRA in vitro and in vivo. However, the effects of LA on NHE3, the Na+/H+ exchanger involved in the coupled electroneutral NaCl absorption, are not known. Current studies were, therefore, undertaken to investigate the effects of LA on the function and expression of NHE3 and to determine the mechanisms involved. Treatment of Caco2 cells with LA or its conditioned culture supernatant (CS) for 8–24 h resulted in a significant increase in Na+/H+ exchange activity, mRNA, and protein levels of NHE3. LA-CS upregulation of NHE3 function and expression was also observed in SK-CO15 cells, a human colonic adenocarcinoma cell line. Additionally, LA treatment increased NHE3 promoter activity, suggesting involvement of transcriptional mechanisms. In vivo, mice gavaged with live LA showed significant increase in NHE3 mRNA and protein expression in the ileum and colonic regions. In conclusion, LA-induced increase in NHE3 expression may contribute to the upregulation of intestinal electrolyte absorption and might underlie the potential antidiarrheal effects of probiotics. PMID:23086913

  8. Nonsynonymous single nucleotide polymorphisms of NHE3 differentially decrease NHE3 transporter activity

    PubMed Central

    Zhu, Xinjun Cindy; Sarker, Rafiquel; Horton, John R.; Chakraborty, Molee; Chen, Tian-E; Tse, C. Ming; Cha, Boyoung

    2015-01-01

    Genetic determinants appear to play a role in susceptibility to chronic diarrhea, but the genetic abnormalities involved have only been identified in a few conditions. The Na+/H+ exchanger 3 (NHE3) accounts for a large fraction of physiologic intestinal Na+ absorption. It is highly regulated through effects on its intracellular COOH-terminal regulatory domain. The impact of genetic variation in the NHE3 gene, such as single nucleotide polymorphisms (SNPs), on transporter activity remains unexplored. From a total of 458 SNPs identified in the entire NHE3 gene, we identified three nonsynonymous mutations (R474Q, V567M, and R799C), which were all in the protein's intracellular COOH-terminal domain. Here we evaluated whether these SNPs affect NHE3 activity by expressing them in a mammalian cell line that is null for all plasma membrane NHEs. These variants significantly reduced basal NHE3 transporter activity through a reduction in intrinsic NHE3 function in variant R474Q, abnormal trafficking in variant V567M, or defects in both intrinsic NHE3 function and trafficking in variant R799C. In addition, variants NHE3 R474Q and R799C failed to respond to acute dexamethasone stimulation, suggesting cells with these mutant proteins might be defective in NHE3 function during postprandial stimulation and perhaps under stressful conditions. Finally, variant R474Q was shown to exhibit an aberrant interaction with calcineurin B homologous protein (CHP), an NHE3 regulatory protein required for basal NHE3 activity. Taken together, these results demonstrate decreased transport activity in three SNPs of NHE3 and provide mechanistic insight into how these SNPs impact NHE3 function. PMID:25715704

  9. Physiological relevance of cell-specific distribution patterns of CFTR, NKCC1, NBCe1, and NHE3 along the crypt-villus axis in the intestine

    PubMed Central

    Jakab, Robert L.; Collaco, Anne M.

    2011-01-01

    We examined the cell-specific subcellular expression patterns for sodium- and potassium-coupled chloride (NaK2Cl) cotransporter 1 (NKCC1), Na+ bicarbonate cotransporter (NBCe1), cystic fibrosis transmembrane conductance regulator (CFTR), and Na+/H+ exchanger 3 (NHE3) to understand the functional plasticity and synchronization of ion transport functions along the crypt-villus axis and its relevance to intestinal disease. In the unstimulated intestine, all small intestinal villus enterocytes coexpressed apical CFTR and NHE3, basolateral NBCe1, and mostly intracellular NKCC1. All (crypt and villus) goblet cells strongly expressed basolateral NKCC1 (at approximately three-fold higher levels than villus enterocytes), but no CFTR, NBCe1, or NHE3. Lower crypt cells coexpressed apical CFTR and basolateral NKCC1, but no NHE3 or NBCe1 (except NBCe1-expressing proximal colonic crypts). CFTR, NBCe1, and NKCC1 colocalized with markers of early and recycling endosomes, implicating endocytic recycling in cell-specific anion transport. Brunner's glands of the proximal duodenum coexpressed high levels of apical/subapical CFTR and basolateral NKCC1, but very low levels of NBCe1, consistent with secretion of Cl−-enriched fluid into the crypt. The cholinergic agonist carbachol rapidly (within 10 min) reduced cell volume along the entire crypt/villus axis and promoted NHE3 internalization into early endosomes. In contrast, carbachol induced membrane recruitment of NKCC1 and CFTR in all crypt and villus enterocytes, NKCC1 in all goblet cells, and NBCe1 in all villus enterocytes. These observations support regulated vesicle traffic in Cl− secretion by goblet cells and Cl− and HCO3− secretion by villus enterocytes during the transient phase of cholinergic stimulation. Overall, the carbachol-induced membrane trafficking profile of the four ion transporters supports functional plasticity of the small intestinal villus epithelium that enables it to conduct both absorptive and

  10. Caffeine-induced diuresis and natriuresis is independent of renal tubular NHE3

    PubMed Central

    Fenton, Robert A.; Poulsen, Søren B.; de la Mora Chavez, Samantha; Soleimani, Manoocher; Busslinger, Meinrad; Rieg, Timo

    2015-01-01

    Caffeine is one of the most widely consumed behavioral substances. We have previously shown that caffeine- and theophylline-induced inhibition of renal reabsorption causes diuresis and natriuresis, an effect that requires functional adenosine A1 receptors. In this study, we tested the hypothesis that blocking the Gi protein-coupled adenosine A1 receptor via the nonselective adenosine receptor antagonist caffeine changes Na+/H+ exchanger isoform 3 (NHE3) localization and phosphorylation, resulting in diuresis and natriuresis. We generated tubulus-specific NHE3 knockout mice (Pax8-Cre), where NHE3 abundance in the S1, S2, and S3 segments of the proximal tubule was completely absent or severely reduced (>85%) in the thick ascending limb. Consumption of fluid and food, as well as glomerular filtration rate, were comparable in control or tubulus-specific NHE3 knockout mice under basal conditions, while urinary pH was significantly more alkaline without evidence for metabolic acidosis. Caffeine self-administration increased total fluid and food intake comparably between genotypes, without significant differences in consumption of caffeinated solution. Acute caffeine application via oral gavage elicited a diuresis and natriuresis that was comparable between control and tubulus-specific NHE3 knockout mice. The diuretic and natriuretic response was independent of changes in total NHE3 expression, phosphorylation of serine-552 and serine-605, or apical plasma membrane NHE3 localization. Although caffeine had no clear effect on localization of the basolateral Na+/bicarbonate cotransporter NBCe1, pretreatment with DIDS inhibited caffeine-induced diuresis and natriuresis. In summary, NHE3 is not required for caffeine-induced diuresis and natriuresis. PMID:25925253

  11. Transcriptional regulation of the human Na{sup +}/H{sup +} exchanger NHE3 by serotonin in intestinal epithelial cells

    SciTech Connect

    Amin, Md Ruhul; Ghannad, Leda; Othman, Ahmad; Gill, Ravinder K.; Dudeja, Pradeep K.; Ramaswamy, Krishnamurthy; Malakooti, Jaleh

    2009-05-08

    Serotonin (5-HT) decreases NHE2 and NHE3 activities under acute conditions in human intestinal epithelial cells. Here, we have investigated the effects of 5-HT on expression of the human NHE3 gene and the mechanisms underlying its transcriptional regulation in differentiated C2BBe1 cells. Treatment of the human intestinal epithelial cell line, C2BBe1, with 5-HT (20 {mu}M) resulted in a significant decrease in NHE3 mRNA and protein expression. In transient transfection studies, 5-HT repressed the NHE3 promoter activity by {approx}55%. The repression of the NHE3 promoter activity in response to 5-HT was accompanied by reduced DNA-binding activity of transcription factors Sp1 and Sp3 to the NHE3 promoter without alteration in their nuclear levels. Pharmacological inhibitors of protein kinase C reversed the inhibitory effect of 5-HT on the promoter activity. Our data indicate that 5-HT suppresses the transcriptional activity of the NHE3 promoter and this effect may be mediated by PKC{alpha} and modulation of DNA-binding affinities of Sp1 and Sp3.

  12. Regulation of NHE3 by lysophosphatidic acid is mediated by phosphorylation of NHE3 by RSK2.

    PubMed

    No, Yi Ran; He, Peijian; Yoo, Byong Kwon; Yun, C Chris

    2015-07-01

    Na(+)/H(+) exchange by Na(+)/H(+) exchanger 3 (NHE3) is a major route of sodium absorption in the intestine and kidney. We have shown previously that lysophosphatidic acid (LPA), a small phospholipid produced ubiquitously by all types of cells, stimulates NHE3 via LPA5 receptor. Stimulation of NHE3 activity by LPA involves LPA5 transactivating EGF receptor (EGFR) in the apical membrane. EGFR activates proline-rich tyrosine kinase 2 (Pyk2) and ERK, both of which are necessary for NHE3 regulation. However, Pyk2 and ERK are regulated by EGFR via independent pathways and appear to converge on an unidentified intermediate that ultimately targets NHE3. The p90 ribosomal S6 kinase (RSK) family of Ser/Thr protein kinases is a known effector of EGFR and ERK. Hence, we hypothesized that RSK may be the convergent effector of Pyk2 and ERK although it is not known whether Pyk2 regulates RSK. In this study, we show that Pyk2 is necessary for the maintenance of phosphoinositide-dependent kinase 1 (PDK1) autophosphorylation, and knockdown of Pyk2 or PDK1 mitigated LPA-induced phosphorylation of RSK and stimulation of NHE3 activity. Additionally, we show that RSK2, but not RSK1, is responsible for NHE3 regulation. RSK2 interacts with NHE3 at the apical membrane domain, where it phosphorylates NHE3. Alteration of S663 of NHE3 ablated LPA-induced phosphorylation of NHE3 and stimulation of the transport activity. Our study identifies RSK2 as a new kinase that regulates NHE3 activity by direct phosphorylation. PMID:25855080

  13. Regulation of NHE3 by lysophosphatidic acid is mediated by phosphorylation of NHE3 by RSK2

    PubMed Central

    No, Yi Ran; He, Peijian; Yoo, Byong Kwon

    2015-01-01

    Na+/H+ exchange by Na+/H+ exchanger 3 (NHE3) is a major route of sodium absorption in the intestine and kidney. We have shown previously that lysophosphatidic acid (LPA), a small phospholipid produced ubiquitously by all types of cells, stimulates NHE3 via LPA5 receptor. Stimulation of NHE3 activity by LPA involves LPA5 transactivating EGF receptor (EGFR) in the apical membrane. EGFR activates proline-rich tyrosine kinase 2 (Pyk2) and ERK, both of which are necessary for NHE3 regulation. However, Pyk2 and ERK are regulated by EGFR via independent pathways and appear to converge on an unidentified intermediate that ultimately targets NHE3. The p90 ribosomal S6 kinase (RSK) family of Ser/Thr protein kinases is a known effector of EGFR and ERK. Hence, we hypothesized that RSK may be the convergent effector of Pyk2 and ERK although it is not known whether Pyk2 regulates RSK. In this study, we show that Pyk2 is necessary for the maintenance of phosphoinositide-dependent kinase 1 (PDK1) autophosphorylation, and knockdown of Pyk2 or PDK1 mitigated LPA-induced phosphorylation of RSK and stimulation of NHE3 activity. Additionally, we show that RSK2, but not RSK1, is responsible for NHE3 regulation. RSK2 interacts with NHE3 at the apical membrane domain, where it phosphorylates NHE3. Alteration of S663 of NHE3 ablated LPA-induced phosphorylation of NHE3 and stimulation of the transport activity. Our study identifies RSK2 as a new kinase that regulates NHE3 activity by direct phosphorylation. PMID:25855080

  14. Casein Kinase 2 Binds to the C Terminus of Na+/H+ exchanger 3 (NHE3) and Stimulates NHE3 Basal Activity by Phosphorylating a Separate Site in NHE3

    PubMed Central

    Sarker, Rafiquel; Grønborg, Mads; Cha, Boyoung; Mohan, Sachin; Chen, Yueping; Pandey, Akhilesh; Litchfield, David

    2008-01-01

    Na+/H+ exchanger 3 (NHE3) is the epithelial-brush border isoform responsible for most intestinal and renal Na+ absorption. Its activity is both up- and down-regulated under normal physiological conditions, and it is inhibited in most diarrheal diseases. NHE3 is phosphorylated under basal conditions and Ser/Thr phosphatase inhibitors stimulate basal exchange activity; however, the kinases involved are unknown. To identify kinases that regulate NHE3 under basal conditions, NHE3 was immunoprecipitated; LC-MS/MS of trypsinized NHE3 identified a novel phosphorylation site at S719 of the C terminus, which was predicted to be a casein kinase 2 (CK2) phosphorylation site. This was confirmed by an in vitro kinase assay. The NHE3-S719A mutant but not NHE3-S719D had reduced NHE3 activity due to less plasma membrane NHE3. This was due to reduced exocytosis plus decreased plasma membrane delivery of newly synthesized NHE3. Also, NHE3 activity was inhibited by the CK2 inhibitor 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole DMAT when wild-type NHE3 was expressed in fibroblasts and Caco-2 cells, but the NHE3-S719 mutant was fully resistant to DMAT. CK2 bound to the NHE3 C-terminal domain, between amino acids 590 and 667, a site different from the site it phosphorylates. CK2 binds to the NHE3 C terminus and stimulates basal NHE3 activity by phosphorylating a separate single site on the NHE3 C terminus (S719), which affects NHE3 trafficking. PMID:18614797

  15. NHE3 function and phosphorylation are regulated by a calyculin A-sensitive phosphatase

    PubMed Central

    Dynia, Diane W.; Steinmetz, Amy G.

    2010-01-01

    Na+/H+ exchanger 3 (NHE3) is phosphorylated and regulated by multiple kinases, including PKA, SGK1, and CK2; however, the role of phosphatases in the dephosphorylation and regulation of NHE3 remains unknown. The purpose of this study was to determine whether serine/threonine phosphatases alter NHE3 activity and phosphorylation and, if so, at which sites. To this end, we first examined the effects of calyculin A [a combined protein phosphatase 1 (PP1) and PP2A inhibitor] and okadaic acid (a PP2A inhibitor) on general and site-specific NHE3 phosphorylation. Calyculin A induced a phosphorylation-dependent NHE3 gel mobility shift and increased NHE3 phosphorylation at serines 552 and 605. No change in NHE3 phosphorylation was detected after okadaic acid treatment. An NHE3 gel mobility shift was also evident in calyculin A-treated COS-7 cells transfected with either wild-type or mutant (S552A, S605G, S661A, S716A) rat NHE3. Since the NHE3 gel mobility shift occurred despite mutation of known phosphorylation sites, novel sites of phosphorylation must also exist. Next, we assayed NHE3 activity in response to calyculin A and okadaic acid and found that calyculin A induced a 24% inhibition of NHE3 activity, whereas okadaic acid had no effect. When all known NHE3 phosphorylation sites were mutated, calyculin A induced a stimulation of NHE3 activity, demonstrating a functional significance for the novel phosphorylation sites. Finally, we established that the PP1 catalytic subunit can directly dephosphorylate immunopurified NHE3 in vitro. In conclusion, our data demonstrate that a calyculin A-sensitive phosphatase, most likely PP1, is involved in the regulation and dephosphorylation of NHE3 at known and novel sites. PMID:20015946

  16. Restoration of Na+/H+ exchanger NHE3-containing macrocomplexes ameliorates diabetes-associated fluid loss

    PubMed Central

    He, Peijian; Zhao, Luqing; Zhu, Lixin; Weinman, Edward J.; De Giorgio, Roberto; Koval, Michael; Srinivasan, Shanthi; Yun, C. Chris

    2015-01-01

    Diarrhea is one of the troublesome complications of diabetes, and the underlying causes of this problem are complex. Here, we investigated whether altered electrolyte transport contributes to diabetic diarrhea. We found that the expression of Na+/H+ exchanger NHE3 and several scaffold proteins, including NHE3 regulatory factors (NHERFs), inositol trisphosphate (IP3) receptor-binding protein released with IP3 (IRBIT), and ezrin, was decreased in the intestinal brush border membrane (BBM) of mice with streptozotocin-induced diabetes. Treatment of diabetic mice with insulin restored intestinal NHE3 activity and fluid absorption. Molecular analysis revealed that NHE3, NHERF1, IRBIT, and ezrin form macrocomplexes, which are perturbed under diabetic conditions, and insulin administration reconstituted these macrocomplexes and restored NHE3 expression in the BBM. Silencing of NHERF1 or IRBIT prevented NHE3 trafficking to the BBM and insulin-dependent NHE3 activation. IRBIT facilitated the interaction of NHE3 with NHERF1 via protein kinase D2–dependent phosphorylation. Insulin stimulated ezrin phosphorylation, which enhanced the interaction of ezrin with NHERF1, IRBIT, and NHE3. Additionally, oral administration of lysophosphatidic acid (LPA) increased NHE3 activity and fluid absorption in diabetic mice via an insulin-independent pathway. Together, these findings indicate the importance of NHE3 in diabetic diarrhea and suggest LPA administration as a potential therapeutic strategy for management of diabetic diarrhea. PMID:26258413

  17. Functional dissection of the lck proximal promoter.

    PubMed Central

    Allen, J M; Forbush, K A; Perlmutter, R M

    1992-01-01

    The lck gene encodes a protein tyrosine kinase that participates in lymphocyte-specific signal transduction pathways. Previous studies have established that lck transcription is regulated by two distinct promoter elements termed proximal (or 3') and distal (or 5'). The proximal promoter is active almost exclusively in thymocytes and becomes inactive later during T-cell maturation. To dissect the mechanisms responsible for lck gene regulation, we generated transgenic animals bearing 5' truncations in the proximal promoter element. Sequences between -584 and +37 with respect to the proximal promoter transcription start site act to direct tissue-specific and temporally correct transcription of either a tagged version of the lck gene itself or a heterologous reporter sequence (lacZ). This region contains binding sites for at least five distinct nuclear proteins, of which one is found only in cells that support proximal lck promoter activity and a second appears only in nonexpressing cells. Interestingly, the transcribed region of the lck gene contains positive control elements that can substantially boost expression from minimal (-130 bp) proximal promoter constructs. These results provide a basis for the biochemical dissection of transcriptional regulators that act at defined points during T-cell development. Images PMID:1588967

  18. Role of the Na+/H+ exchanger 3 in angiotensin II-induced hypertension in NHE3-deficient mice with transgenic rescue of NHE3 in small intestines

    PubMed Central

    Li, Xiao C; Shull, Gary E; Miguel-Qin, Elisa; Chen, Fang; Zhuo, Jia L

    2015-01-01

    The role of Na+/H+ exchanger 3 (NHE3) in the kidney in angiotensin II (ANG II)-induced hypertension remains unknown. The present study used global NHE3-deficient mice with transgenic rescue of the Nhe3 gene in small intestines (tgNhe3−/−) to test the hypothesis that genetic deletion of NHE3 selectively in the kidney attenuates ANG II-induced hypertension. Six groups of wild-type (tgNhe3+/+) and tgNhe3−/− mice were infused with either vehicle or ANG II (1.5 mg/kg/day, i.p., 2 weeks, or 10 nmol/min, i.v., 30 min), treated with or without losartan (20 mg/kg/day, p.o.) for 2 weeks. Basal systolic blood pressure (SBP) and mean intra-arterial blood pressure (MAP) were significantly lower in tgNhe3−/− mice (P < 0.01). Basal glomerular filtration rate, 24 h urine excretion, urinary Na+ excretion, urinary K+ excretion, and urinary Cl− excretion were significantly lower in tgNhe3−/− mice (P < 0.01). These responses were associated with significantly elevated plasma ANG II and aldosterone levels, and marked upregulation in aquaporin 1, the Na+/HCO3 cotransporter, the α1 subunit isoform of Na+/K+-ATPase, protein kinase Cα, MAP kinases ERK1/2, and glycogen synthase kinase 3 α/β in the renal cortex of tgNhe3−/− mice (P < 0.01). ANG II infusion markedly increased SBP and MAP and renal cortical transporter and signaling proteins in tgNhe3+/+, as expected, but all of these responses to ANG II were attenuated in tgNhe3−/− mice (P < 0.01). These results suggest that NHE3 in the kidney is necessary for maintaining normal blood pressure and fully developing ANG II-dependent hypertension. PMID:26564064

  19. Promoting proximal formative assessment with relational discourse

    NASA Astrophysics Data System (ADS)

    Scherr, Rachel E.; Close, Hunter G.; McKagan, Sarah B.

    2012-02-01

    The practice of proximal formative assessment - the continual, responsive attention to students' developing understanding as it is expressed in real time - depends on students' sharing their ideas with instructors and on teachers' attending to them. Rogerian psychology presents an account of the conditions under which proximal formative assessment may be promoted or inhibited: (1) Normal classroom conditions, characterized by evaluation and attention to learning targets, may present threats to students' sense of their own competence and value, causing them to conceal their ideas and reducing the potential for proximal formative assessment. (2) In contrast, discourse patterns characterized by positive anticipation and attention to learner ideas increase the potential for proximal formative assessment and promote self-directed learning. We present an analysis methodology based on these principles and demonstrate its utility for understanding episodes of university physics instruction.

  20. NHE3 phosphorylation via PKCη marks the polarity and orientation of directionally migrating cells

    PubMed Central

    Bola, Sharanya; Zhang, Lei; Reid, Brian; Fu, Guo; Funk, Richard H. W.; Zhao, Min

    2015-01-01

    Endogenous electric fields (EF) may provide an overriding cue for directional cell migration during wound closure. Perceiving a constant direction requires active sodium-hydrogen exchanger (pNHE3) at the leading edge of HEK 293 cells but its activation mechanism is not yet fully understood. Because protein kinase C (PKC) is required in electrotaxis, we asked whether NHE3 is activated by PKC during wound healing. Using pharmacological (pseudosubstrate and edelfosine) inhibition, we showed that inhibition of PKCη isoform impairs directional cell migration in HEK 293 cells in the presence of a persistent directional cue (0.25–0.3 V/mm of EF for 2 h). Further, we found that pNHE3 forms complexes with both PKCη and ɣ-tubulin, suggesting that these molecules may regulate the microtubule-organizing center. In addition, cellular pNHE3 content was reduced significantly when PKCη was inhibited during directional cell migration. Taken together, these data suggest that PKCη-dependent phosphorylation of NHE3 and the formation of pNHE3/PKCη/ɣ-tubulin complexes at the leading edge of the cell are required for directional cell migration in an EF. PMID:24788043

  1. Loss of NHE3 alters gut microbiota composition and influences Bacteroides thetaiotaomicron growth

    PubMed Central

    Engevik, Melinda A.; Aihara, Eitaro; Montrose, Marshall H.; Shull, Gary E.; Hassett, Daniel J.

    2013-01-01

    Changes in the intestinal microbiota have been linked to diabetes, obesity, inflammatory bowel disease, and Clostridium difficile (C. difficile)-associated disease. Despite this, it remains unclear how the intestinal environment, set by ion transport, affects luminal and mucosa-associated bacterial composition. Na+/H+-exchanger isoform 3 (NHE3), a target of C. difficile toxin B, plays an integral role in intestinal Na+ absorption. Thus the NHE3-deficient mouse model was chosen to examine the effect of pH and ion composition on bacterial growth. We hypothesized that ion transport-induced change in the intestinal environment would lead to alteration of the microbiota. Region-specific changes in ion composition and pH correlated with region-specific alteration of luminal and mucosal-associated bacteria with general decreases in Firmicutes and increases in Bacteroidetes members. Bacteroides thetaiotaomicron (B. thetaiotaomicron) increased in NHE3−/− terminal ileum and was examined in vitro to determine whether altered Na+ was sufficient to affect growth. Increased in vitro growth of B. thetaiotaomicron occurred in 43 mM Na+ correlating with the NHE3−/− mouse terminal ileum [Na+]. NHE3−/− terminal ileum displayed increased fut2 mRNA and fucosylation correlating with B. thetaiotaomicron growth. Inoculation of B. thetaiotaomicron in wild-type and NHE3−/− terminal ileum organoids displayed increased fut2 and fucosylation, indicating that B. thetaiotaomicron alone is sufficient for the increased fucosylation seen in vivo. These data demonstrate that loss of NHE3 alters the intestinal environment, leading to region-specific changes in bacteria, and shed light on the growth requirements of some gut microbiota members, which is vital for creating better treatments of complex diseases with an altered gut microbiota. PMID:24072680

  2. Reduced sodium/proton exchanger NHE3 activity causes congenital sodium diarrhea.

    PubMed

    Janecke, Andreas R; Heinz-Erian, Peter; Yin, Jianyi; Petersen, Britt-Sabina; Franke, Andre; Lechner, Silvia; Fuchs, Irene; Melancon, Serge; Uhlig, Holm H; Travis, Simon; Marinier, Evelyne; Perisic, Vojislav; Ristic, Nina; Gerner, Patrick; Booth, Ian W; Wedenoja, Satu; Baumgartner, Nadja; Vodopiutz, Julia; Frechette-Duval, Marie-Christine; De Lafollie, Jan; Persad, Rabindranath; Warner, Neil; Tse, C Ming; Sud, Karan; Zachos, Nicholas C; Sarker, Rafiquel; Zhu, Xinjun; Muise, Aleixo M; Zimmer, Klaus-Peter; Witt, Heiko; Zoller, Heinz; Donowitz, Mark; Müller, Thomas

    2015-12-01

    Congenital sodium diarrhea (CSD) refers to an intractable diarrhea of intrauterine onset with high fecal sodium loss. CSD is clinically and genetically heterogeneous. Syndromic CSD is caused by SPINT2 mutations. While we recently described four cases of the non-syndromic form of CSD that were caused by dominant activating mutations in intestinal receptor guanylate cyclase C (GC-C), the genetic cause for the majority of CSD is still unknown. Therefore, we aimed to determine the genetic cause for non-GC-C non-syndromic CSD in 18 patients from 16 unrelated families applying whole-exome sequencing and/or chromosomal microarray analyses and/or direct Sanger sequencing. SLC9A3 missense, splicing and truncation mutations, including an instance of uniparental disomy, and whole-gene deletion were identified in nine patients from eight families with CSD. Two of these nine patients developed inflammatory bowel disease (IBD) at 4 and 16 years of age. SLC9A3 encodes Na(+)/H(+) antiporter 3 (NHE3), which is the major intestinal brush-border Na(+)/H(+) exchanger. All mutations were in the NHE3 N-terminal transport domain, and all missense mutations were in the putative membrane-spanning domains. Identified SLC9A3 missense mutations were functionally characterized in plasma membrane NHE null fibroblasts. SLC9A3 missense mutations compromised NHE3 activity by reducing basal surface expression and/or loss of basal transport function of NHE3 molecules, whereas acute regulation was normal. This study identifies recessive mutations in NHE3, a downstream target of GC-C, as a cause of CSD and implies primary basal NHE3 malfunction as a predisposition for IBD in a subset of patients. PMID:26358773

  3. Functional role of glucose metabolism, osmotic stress, and sodium-glucose cotransporter isoform-mediated transport on Na+/H+ exchanger isoform 3 activity in the renal proximal tubule.

    PubMed

    Pessoa, Thaissa Dantas; Campos, Luciene Cristina Gastalho; Carraro-Lacroix, Luciene; Girardi, Adriana C C; Malnic, Gerhard

    2014-09-01

    Na(+)-glucose cotransporter 1 (SGLT1)-mediated glucose uptake leads to activation of Na(+)-H(+) exchanger 3 (NHE3) in the intestine by a process that is not dependent on glucose metabolism. This coactivation may be important for postprandial nutrient uptake. However, it remains to be determined whether SGLT-mediated glucose uptake regulates NHE3-mediated NaHCO3 reabsorption in the renal proximal tubule. Considering that this nephron segment also expresses SGLT2 and that the kidneys and intestine show significant variations in daily glucose availability, the goal of this study was to determine the effect of SGLT-mediated glucose uptake on NHE3 activity in the renal proximal tubule. Stationary in vivo microperfusion experiments showed that luminal perfusion with 5 mM glucose stimulates NHE3-mediated bicarbonate reabsorption. This stimulatory effect was mediated by glycolytic metabolism but not through ATP production. Conversely, luminal perfusion with 40 mM glucose inhibited NHE3 because of cell swelling. Notably, pharmacologic inhibition of SGLT activity by Phlorizin produced a marked inhibition of NHE3, even in the absence of glucose. Furthermore, immunofluorescence experiments showed that NHE3 colocalizes with SGLT2 but not SGLT1 in the rat renal proximal tubule. Collectively, these findings show that glucose exerts a bimodal effect on NHE3. The physiologic metabolism of glucose stimulates NHE3 transport activity, whereas, supraphysiologic glucose concentrations inhibit this exchanger. Additionally, Phlorizin-sensitive SGLT transporters and NHE3 interact functionally in the proximal tubule. PMID:24652792

  4. A positioned +1 nucleosome enhances promoter-proximal pausing

    PubMed Central

    Jimeno-González, Silvia; Ceballos-Chávez, María; Reyes, José C.

    2015-01-01

    Chromatin distribution is not uniform along the human genome. In most genes there is a promoter-associated nucleosome free region (NFR) followed by an array of nucleosomes towards the gene body in which the first (+1) nucleosome is strongly positioned. The function of this characteristic chromatin distribution in transcription is not fully understood. Here we show in vivo that the +1 nucleosome plays a role in modulating RNA polymerase II (RNAPII) promoter-proximal pausing. When a +1 nucleosome is strongly positioned, elongating RNAPII has a tendency to stall at the promoter-proximal region, recruits more negative elongation factor (NELF) and produces less mRNA. The nucleosome-induced pause favors pre-mRNA quality control by promoting the addition of the cap to the nascent RNA. Moreover, the uncapped RNAs produced in the absence of a positioned nucleosome are degraded by the 5′-3′ exonuclease XRN2. Interestingly, reducing the levels of the chromatin remodeler ISWI factor SNF2H decreases +1 nucleosome positioning and increases RNAPII pause release. This work demonstrates a function for +1 nucleosome in regulation of transcription elongation, pre-mRNA processing and gene expression. PMID:25735750

  5. Coordinated epithelial NHE3 inhibition and barrier dysfunction are required for TNF-mediated diarrhea in vivo

    PubMed Central

    Clayburgh, Daniel R.; Musch, Mark W.; Leitges, Michael; Fu, Yang-Xin; Turner, Jerrold R.

    2006-01-01

    Acute T cell–mediated diarrhea is associated with increased mucosal expression of proinflammatory cytokines, including the TNF superfamily members TNF and LIGHT. While we have previously shown that epithelial barrier dysfunction induced by myosin light chain kinase (MLCK) is required for the development of diarrhea, MLCK inhibition does not completely restore water absorption. In contrast, although TNF-neutralizing antibodies completely restore water absorption after systemic T cell activation, barrier function is only partially corrected. This suggests that, while barrier dysfunction is critical, other processes must be involved in T cell–mediated diarrhea. To define these processes in vivo, we asked whether individual cytokines might regulate different events in T cell–mediated diarrhea. Both TNF and LIGHT caused MLCK-dependent barrier dysfunction. However, while TNF caused diarrhea, LIGHT enhanced intestinal water absorption. Moreover, TNF, but not LIGHT, inhibited Na+ absorption due to TNF-induced internalization of the brush border Na+/H+ exchanger NHE3. LIGHT did not cause NHE3 internalization. PKCα activation by TNF was responsible for NHE3 internalization, and pharmacological or genetic PKCα inhibition prevented NHE3 internalization, Na+ malabsorption, and diarrhea despite continued barrier dysfunction. These data demonstrate the necessity of coordinated Na+ malabsorption and barrier dysfunction in TNF-induced diarrhea and provide insight into mechanisms of intestinal water transport. PMID:17016558

  6. Transcription Factor Binding Site Positioning in Yeast: Proximal Promoter Motifs Characterize TATA-Less Promoters

    PubMed Central

    Erb, Ionas; van Nimwegen, Erik

    2011-01-01

    The availability of sequence specificities for a substantial fraction of yeast's transcription factors and comparative genomic algorithms for binding site prediction has made it possible to comprehensively annotate transcription factor binding sites genome-wide. Here we use such a genome-wide annotation for comprehensively studying promoter architecture in yeast, focusing on the distribution of transcription factor binding sites relative to transcription start sites, and the architecture of TATA and TATA-less promoters. For most transcription factors, binding sites are positioned further upstream and vary over a wider range in TATA promoters than in TATA-less promoters. In contrast, a group of ‘proximal promoter motifs’ (GAT1/GLN3/DAL80, FKH1/2, PBF1/2, RPN4, NDT80, and ROX1) occur preferentially in TATA-less promoters and show a strong preference for binding close to the transcription start site in these promoters. We provide evidence that suggests that pre-initiation complexes are recruited at TATA sites in TATA promoters and at the sites of the other proximal promoter motifs in TATA-less promoters. TATA-less promoters can generally be classified by the proximal promoter motif they contain, with different classes of TATA-less promoters showing different patterns of transcription factor binding site positioning and nucleosome coverage. These observations suggest that different modes of regulation of transcription initiation may be operating in the different promoter classes. In addition we show that, across all promoter classes, there is a close match between nucleosome free regions and regions of highest transcription factor binding site density. This close agreement between transcription factor binding site density and nucleosome depletion suggests a direct and general competition between transcription factors and nucleosomes for binding to promoters. PMID:21931670

  7. Squalamine, a novel cationic steroid, specifically inhibits the brush-border Na+/H+ exchanger isoform NHE3.

    PubMed

    Akhter, S; Nath, S K; Tse, C M; Williams, J; Zasloff, M; Donowitz, M

    1999-01-01

    Squalamine, an endogenous molecule found in the liver and other tissues of Squalus acanthias, has antibiotic properties and causes changes in endothelial cell shape. The latter suggested that its potential targets might include transport proteins that control cell volume or cell shape. The effect of purified squalamine was examined on cloned Na+/H+ exchanger isoforms NHE1, NHE2, and NHE3 stably transfected in PS120 fibroblasts. Squalamine (1-h pretreatment) decreased the maximal velocity of rabbit NHE3 in a concentration-dependent manner (13, 47, and 57% inhibition with 3, 5, and 7 micrograms/ml, respectively) and also increased K'[H+]i. Squalamine did not affect rabbit NHE1 or NHE2 function. The inhibitory effect of squalamine was 1) time dependent, with no effect of immediate addition and maximum effect with 1 h of exposure, and 2) fully reversible. Squalamine pretreatment of the ileum for 60 min inhibited brush-border membrane vesicle Na+/H+ activity by 51%. Further investigation into the mechanism of squalamine's effects showed that squalamine required the COOH-terminal 76 amino acids of NHE3. Squalamine had no cytotoxic effect at the concentrations studied, as indicated by monitoring lactate dehydrogenase release. These results indicate that squalamine 1) is a specific inhibitor of the brush-border NHE isoform NHE3 and not NHE1 or NHE2, 2) acts in a nontoxic and fully reversible manner, and 3) has a delayed effect, indicating that it may influence brush-border Na+/H+ exchanger function indirectly, through an intracellular signaling pathway or by acting as an intracellular modulator. PMID:9886929

  8. Proximal tubular NHEs: sodium, protons and calcium?

    PubMed Central

    Alexander, R. Todd; Dimke, Henrik; Cordat, Emmanuelle

    2016-01-01

    Na+/H+ exchange activity in the apical membrane of the proximal tubule is fundamental to the reabsorption of Na+ and water from the filtrate. The role of this exchange process in bicarbonate reclamation and, consequently, the maintenance of acid-base homeostasis has been appreciated for at least half a century and remains a pillar of renal tubular physiology. More recently, apical Na+/H+ exchange, mediated by Na+/H+ exchanger isoform 3 (NHE3), has been implicated in proximal tubular reabsorption of Ca2+ and Ca2+ homeostasis in general. Overexpression of NHE3 increased paracellular Ca2+ flux in a proximal tubular cell model. Consistent with this observation, mice with genetic deletion of Nhe3 have a noticable renal Ca2+ leak. These mice also display decreased intestinal Ca2+ uptake and osteopenia. This review highlights the traditional roles of proximal tubular Na+/H+ exchange and summarizes recent novel findings implicating the predominant isoform, NHE3, in Ca2+ homeostasis. PMID:23761670

  9. Short-term regulation of NHE3 by EGF and protein kinase C but not protein kinase A involves vesicle trafficking in epithelial cells and fibroblasts.

    PubMed

    Donowitz, M; Janecki, A; Akhter, S; Cavet, M E; Sanchez, F; Lamprecht, G; Zizak, M; Kwon, W L; Khurana, S; Yun, C H; Tse, C M

    2000-01-01

    NHE3 is an intestinal epithelial isoform Na+/H+ exchanger that is present in the brush border of small intestinal, colonic, and gallbladder Na(+)-absorbing epithelial cells. NHE3 is acutely up- and downregulated in response to some G protein-linked receptors, tyrosine kinase receptors, and protein kinases when studied in intact ileum, when stably expressed in PS120 fibroblasts, and in the few studies reported in the human colon cancer cell line Caco-2. In most cases this is due to changes in Vmax of NHE3, although in response to cAMP and squalamine there are also changes in the K'(H+)i of the exchanger. The mechanism of the Vmax regulation as shown by cell surface biotinylation and confocal microscopy in Caco-2 cells and biotinylation in PS120 cells involves changes in the amount of NHE3 on the plasma membrane. In addition, in some cases there are also changes in turnover number of the exchanger. In some cases, the change in amount of NHE3 in the plasma membrane is associated with a change in the amount of plasma membrane. A combination of biochemical studies and transport/inhibitor studies in intact ileum and Caco-2 cells demonstrated that the increase in brush border Na+/H+ exchange caused by acute exposure to EGF was mediated by PI 3-kinase. PI 3-kinase was also involved in FGF stimulation of NHE3 expressed in fibroblasts. Thus, NHE3 is another example of a transport protein that is acutely regulated in part by changing the amount of the transporter on the plasma membrane by a process that appears to involve vesicle trafficking and also to involve changes in turnover number. PMID:11193592

  10. Luminal Na+/H+ exchange in the proximal tubule

    PubMed Central

    Bobulescu, I. Alexandru

    2010-01-01

    The proximal tubule is critical for whole-organism volume and acid–base homeostasis by reabsorbing filtered water, NaCl, bicarbonate, and citrate, as well as by excreting acid in the form of hydrogen and ammonium ions and producing new bicarbonate in the process. Filtered organic solutes such as amino acids, oligopeptides, and proteins are also retrieved by the proximal tubule. Luminal membrane Na+/H+ exchangers either directly mediate or indirectly contribute to each of these processes. Na+/H+ exchangers are a family of secondary active transporters with diverse tissue and subcellular distributions. Two isoforms, NHE3 and NHE8, are expressed at the luminal membrane of the proximal tubule. NHE3 is the prevalent isoform in adults, is the most extensively studied, and is tightly regulated by a large number of agonists and physiological conditions acting via partially defined molecular mechanisms. Comparatively little is known about NHE8, which is highly expressed at the lumen of the neonatal proximal tubule and is mostly intracellular in adults. This article discusses the physiology of proximal Na+/H+ exchange, the multiple mechanisms of NHE3 regulation, and the reciprocal relationship between NHE3 and NHE8 at the lumen of the proximal tubule. PMID:18853182

  11. Cloning and characterization of Na(+)/H(+) Exchanger isoforms NHE2 and NHE3 from the gill of Pacific dogfish Squalus suckleyi.

    PubMed

    Guffey, Samuel C; Fliegel, Larry; Goss, Greg G

    2015-10-01

    Na(+)/H(+) Exchanger (NHE) proteins mediate cellular and systemic homeostasis of sodium and acid and may be the major sodium uptake method for fishes. We cloned and sequenced NHE2 and NHE3 from the gill of the North Pacific Spiny Dogfish shark Squalus suckleyi and expressed them in functional form in NHE-deficient (AP-1) cell lines. Estimated IC50 for inhibition of NHE activity by amiloride and EIPA were 55 μmol l(-1) and 4.8 μmol l(-1), respectively, for NHE2 and 9 μmol l(-1) and 24 μmol l(-1), respectively, for NHE3. Phenamil at 100 μmol l(-1) caused less than 16% inhibition of activity for each isoform. Although the IC50 are similar for the two isoforms, dfNHE2 is less sensitive than human NHE2 to inhibition by amiloride and EIPA, while dfNHE3 is more sensitive than human NHE3. These IC50 estimates should be considered when selecting inhibitor doses for fishes and for reinterpretation of previous studies that use these pharmacological agents. PMID:26112825

  12. Regulatory elements mediating transcription from the Drosophila melanogaster actin 5C proximal promoter.

    PubMed Central

    Chung, Y T; Keller, E B

    1990-01-01

    The major cytoskeletal actin gene of Drosophila melanogaster, the actin 5C gene, has two promoters, the proximal one of which controls constitutive synthesis of actin in all growing tissues. To locate regulatory elements required for constitutive activity of the proximal promoter, mutants of this promoter were fused to the bacterial chloramphenicol acetyltransferase gene and assayed for transient expression activity in cultured Drosophila embryonic Schneider line 2 cells. An essential regulatory element has been located 313 base pairs upstream from the cap site. Deletion of this element lowered expression to one-third of the wild-type level. The element has the sequence AAGTTGTAGTTG, as shown by protein-binding footprinting with the reagent methidiumpropyl-EDTA-Fe(II). This element is probably not a general one, since it was not detected in a search of the published 5'-flanking sequences of 27 Drosophila genes. In addition to this regulatory element, there are five GAGA elements in the actin 5C proximal promoter, some or all of which are essential for the promoter activity as shown by an in vivo competition assay. Although this promoter has no classical TATA element, there is an essential promoter region about 35 base pairs upstream from the cap site that could be a TATA surrogate. The promoter also shows sequences homologous to the alcohol dehydrogenase factor 1-binding site and to the core of the vertebrate serum response element, but mutations of these sites did not affect promoter activity in transient expression assays. Images PMID:2104658

  13. Tumor-promoting phorbol esters effect alkalinization of canine renal proximal tubular cells

    SciTech Connect

    Mellas, J.; Hammerman, M.R.

    1986-03-01

    We have demonstrated the presence of specific receptors for tumor-promoting phorbol esters in the plasma membrane of the canine renal proximal tubular cell. These compounds affect proximal tubular metabolism in vitro. For example, we have shown that they inhibit gluconeogenesis in canine renal proximal tubular segments. Tumor-promoting phorbol esters have been shown to effect alkalinization of non-renal cells, by enhancing Na/sup +/-H/sup +/ exchange across the plasma membrane. To determine whether the actions of tumor-promoting phorbol esters in proximal tubular segments might be mediated by a similar process, we incubated suspensions of segments from dog kidney with these compounds and measured changes in intracellular pH using (/sup 14/C)-5,5-dimethoxazoladine-2-4-dione (DMO) and flow dialysis. Incubation of segments with phorbol 12,13 dibutyrate, but not inactive phorbol ester, 4 ..gamma.. phorbol, effected alkalinization of cells within the segments in a concentration-dependent manner. Alkalinization was dependent upon the presence of extracellular (Na/sup +/) > intracellular (Na/sup +/), was prevented by amiloride and was demonstrable in the presence of SITS. Our findings suggest that tumor-promoting esters stimulate the Na/sup +/-H/sup +/ exchanger known to be present in the brush border membrane of the renal proximal tubular cell. It is possible that the stimulation reflects a mechanism by which phorbol esters affect metabolic processes in these cells.

  14. Carbachol-induced MUC17 endocytosis is concomitant with NHE3 internalization and CFTR membrane recruitment in enterocytes.

    PubMed

    Pelaseyed, Thaher; Gustafsson, Jenny K; Gustafsson, Ida J; Ermund, Anna; Hansson, Gunnar C

    2013-08-15

    We have reported that transmembrane mucin MUC17 binds PDZ protein PDZK1, which retains MUC17 apically in enterocytes. MUC17 and transmembrane mucins MUC3 and MUC12 are suggested to build the enterocyte apical glycocalyx. Carbachol (CCh) stimulation of the small intestine results in gel-forming mucin secretion from goblet cells, something that requires adjacent enterocytes to secrete chloride and bicarbonate for proper mucin formation. Surface labeling and confocal imaging demonstrated that apically expressed MUC17 in Caco-2 cells and Muc3(17) in murine enterocytes were endocytosed upon stimulation with CCh. Relocation of MUC17 in response to CCh was specific as MUC3 and MUC12 did not relocate following CCh stimulation. MUC17 colocalized with PDZK1 under basal conditions, while MUC17 relocated to the terminal web and into early endosomes after CCh stimulation. CCh stimulation concomitantly internalized the Na(+/)H(+) exchanger 3 (NHE3) and recruited cystic fibrosis transmembrane conductance regulator (CFTR) to the apical membranes, a process that was important for CFTR-mediated bicarbonate secretion necessary for proper gel-forming mucin unfolding. The reason for the specific internalization of MUC17 is not understood, but it could limit the diffusion barrier for ion secretion caused by the apical enterocyte glycocalyx or alternatively act to sample luminal bacteria. Our results reveal well-orchestrated mucus secretion and trafficking of ion channels and the MUC17 mucin. PMID:23784542

  15. Differential Association of the Na+/H+ Exchanger Regulatory Factor (NHERF) Family of Adaptor Proteins with the Raft-and the Non-Raft Brush Border Membrane Fractions of NHE3

    PubMed Central

    Sultan, Ayesha; Luo, Min; Yu, Qin; Riederer, Brigitte; Xia, Weiliang; Chen, Mingmin; Lissner, Simone; Gessner, Johannes E.; Donowitz, Mark; Yun, C. Chris; deJonge, Hugo; Lamprecht, Georg; Seidler, Ursula

    2014-01-01

    Background/Aims Trafficking, brush border membrane (BBM) retention, and signal-specific regulation of the Na+/H+ exchanger NHE3 is regulated by the Na+/H+ Exchanger Regulatory Factor (NHERF) family of PDZ-adaptor proteins, which enable the formation of multiprotein complexes. It is unclear, however, what determines signal specificity of these NHERFs. Thus, we studied the association of NHE3, NHERF1 (EBP50), NHERF2 (E3KARP), and NHERF3 (PDZK1) with lipid rafts in murine small intestinal BBM. Methods Detergent resistant membranes (“lipid rafts”) were isolated by floatation of Triton X-incubated small intestinal BBM from a variety of knockout mouse strains in an Optiprep step gradient. Acid-activated NHE3 activity was measured fluorometrically in BCECF-loaded microdissected villi, or by assessment of CO2/HCO3− mediated increase in fluid absorption in perfused jejunal loops of anethetized mice. Results NHE3 was found to partially associate with lipid rafts in the native BBM, and NHE3 raft association had an impact on NHE3 transport activity and regulation in vivo. NHERF1, 2 and 3 were differentially distributed to rafts and non-rafts, with NHERF2 being most raft-associated and NHERF3 entirely non-raft associated. NHERF2 expression enhanced the localization of NHE3 to membrane rafts. The use of acid sphingomyelinase-deficient mice, which have altered membrane lipid as well as lipid raft composition, allowed us to test the validity of the lipid raft concept in vivo. Conclusions The differential association of the NHERFs with the raft-associated and the non-raft fraction of NHE3 in the brush border membrane is one component of the differential and signal-specific NHE3 regulation by the different NHERFs. PMID:24297041

  16. Grouper tshβ Promoter-Driven Transgenic Zebrafish Marks Proximal Kidney Tubule Development

    PubMed Central

    Wang, Yang; Sun, Zhi-Hui; Zhou, Li; Li, Zhi; Gui, Jian-Fang

    2014-01-01

    Kidney tubule plays a critical role in recovering or secreting solutes, but the detailed morphogenesis remains unclear. Our previous studies have found that grouper tshβ (gtshβ) is also expressed in kidney, however, the distribution significance is still unknown. To understand the gtshβ role and kidney tubule morphogenesis, here, we have generated a transgenic zebrafish line Tg(gtshβ:GFP) with green fluorescent protein driven by the gtshβ promoter. Similar to the endogenous tshβ in zebrafish or in grouper, the gtshβ promoter-driven GFP is expressed in pituitary and kidney, and the developing details of proximal kidney tubule are marked in the transgenic zebrafish line. The gfp initially transcribes at 16 hours post fertilization (hpf) above the dorsal mesentery, and partially co-localizes with pronephric tubular markers slc20a1a and cdh17. Significantly, the GFP specifically localizes in proximal pronephric segments during embryogenesis and resides at kidney duct epithelium in adult fish. To test whether the gtshβ promoter-driven GFP may serve as a readout signal of the tubular development, we have treated the embryos with retinoic acid signaing (RA) reagents, in which exogenous RA addition results in a distal extension of the proximal segments, while RA inhibition induces a weakness and shortness of the proximal segments. Therefore, this transgenic line provides a useful tool for genetic or chemical analysis of kidney tubule. PMID:24905828

  17. Interference in transcription of overexpressed genes by promoter-proximal downstream sequences.

    PubMed

    Turchinovich, A; Surowy, H M; Tonevitsky, A G; Burwinkel, B

    2016-01-01

    Despite a high sequence homology among four human RNAi-effectors Argonaute proteins and their coding sequences, the efficiency of ectopic overexpression of AGO3 and AGO4 coding sequences in human cells is greatly reduced as compared to AGO1 and AGO2. While investigating this phenomenon, we documented the existence of previously uncharacterized mechanism of gene expression regulation, which is manifested in greatly varying basal transcription levels from the RNApolII promoters depending on the promoter-proximal downstream sequences. Specifically, we show that distinct overexpression of Argonaute coding sequences cannot be explained by mRNA degradation in the cytoplasm or nucleus, and exhibits on transcriptional level. Furthermore, the first 1000-2000 nt located immediately downstream the promoter had the most critical influence on ectopic gene overexpression. The transcription inhibiting effect, associated with those downstream sequences, subsided with increasing distance to the promoter and positively correlated with promoter strength. We hypothesize that the same mechanism, which we named promoter proximal inhibition (PPI), could generally contribute to basal transcription levels of genes, and could be mainly responsible for the essence of difficult-to-express recombinant proteins. Finally, our data reveal that expression of recombinant proteins in human cells can be greatly enhanced by using more permissive promoter adjacent downstream sequences. PMID:27485701

  18. Interference in transcription of overexpressed genes by promoter-proximal downstream sequences

    PubMed Central

    Turchinovich, A.; Surowy, H. M.; Tonevitsky, A. G.; Burwinkel, B.

    2016-01-01

    Despite a high sequence homology among four human RNAi-effectors Argonaute proteins and their coding sequences, the efficiency of ectopic overexpression of AGO3 and AGO4 coding sequences in human cells is greatly reduced as compared to AGO1 and AGO2. While investigating this phenomenon, we documented the existence of previously uncharacterized mechanism of gene expression regulation, which is manifested in greatly varying basal transcription levels from the RNApolII promoters depending on the promoter-proximal downstream sequences. Specifically, we show that distinct overexpression of Argonaute coding sequences cannot be explained by mRNA degradation in the cytoplasm or nucleus, and exhibits on transcriptional level. Furthermore, the first 1000–2000 nt located immediately downstream the promoter had the most critical influence on ectopic gene overexpression. The transcription inhibiting effect, associated with those downstream sequences, subsided with increasing distance to the promoter and positively correlated with promoter strength. We hypothesize that the same mechanism, which we named promoter proximal inhibition (PPI), could generally contribute to basal transcription levels of genes, and could be mainly responsible for the essence of difficult-to-express recombinant proteins. Finally, our data reveal that expression of recombinant proteins in human cells can be greatly enhanced by using more permissive promoter adjacent downstream sequences. PMID:27485701

  19. In vivo evidence for interferon-gamma-mediated homeostatic mechanisms in small intestine of the NHE3 Na+/H+ exchanger knockout model of congenital diarrhea.

    PubMed

    Woo, Alison L; Gildea, Lucy A; Tack, Leslie M; Miller, Marian L; Spicer, Zachary; Millhorn, David E; Finkelman, Fred D; Hassett, Daniel J; Shull, Gary E

    2002-12-13

    Mice lacking NHE3, the major absorptive Na(+)/H(+) exchanger in the intestine, are the only animal model of congenital diarrhea. To identify molecular changes underlying compensatory mechanisms activated in chronic diarrheas, cDNA microarrays and Northern blot analyses were used to compare global mRNA expression patterns in small intestine of NHE3-deficient and wild-type mice. Among the genes identified were members of the RegIII family of growth factors, which may contribute to the increased absorptive area, and a large number of interferon-gamma-responsive genes. The latter finding is of particular interest, since interferon-gamma has been shown to regulate ion transporter activities in intestinal epithelial cells. Serum interferon-gamma was elevated 5-fold in NHE3-deficient mice; however, there was no evidence of inflammation, and unlike conditions such as inflammatory bowel disease, levels of other cytokines were unchanged. In addition, quantitative PCR analysis showed that up-regulation of interferon-gamma mRNA was localized to the small intestine and did not occur in the colon, spleen, or kidney. These in vivo data suggest that elevated interferon-gamma, produced by gut-associated lymphoid tissue in the small intestine, is part of a homeostatic mechanism that is activated in response to the intestinal absorptive defect in order to regulate the fluidity of the intestinal tract. PMID:12370192

  20. SMADs and FOXL2 synergistically regulate murine FSHbeta transcription via a conserved proximal promoter element.

    PubMed

    Tran, Stella; Lamba, Pankaj; Wang, Ying; Bernard, Daniel J

    2011-07-01

    Pituitary FSH regulates ovarian and testicular function. Activins stimulate FSHβ subunit (Fshb) gene transcription in gonadotrope cells, the rate-limiting step in mature FSH synthesis. Activin A-induced murine Fshb gene transcription in immortalized gonadotropes is dependent on homolog of Drosophila mothers against decapentaplegic (SMAD) proteins as well as the forkhead transcription factor FOXL2 (FOXL2). Here, we demonstrate that FOXL2 synergizes with SMAD2, SMAD3, and SMAD4 to stimulate murine Fshb promoter-reporter activity in heterologous cells. Moreover, SMAD3-induction of Fshb promoter activity or endogenous mRNA expression is dependent upon endogenous FOXL2 in homologous cells. FOXL2/SMAD synergy requires binding of both FOXL2 and SMAD3 or SMAD4 to DNA. Of three putative forkhead-binding elements identified in the murine Fshb promoter, only the most proximal is absolutely required for activin A induction of reporter activity in homologous cells. Additionally, mutations to the minimal SMAD-binding element adjacent to the proximal forkhead-binding element abrogate activin A or FOXL2/SMAD3 induction of reporter activity. In contrast, a mutation that impairs an adjacent PBX1/PREP1 (pre-B cell leukemia transcription factor 1-PBX/knotted-1 homeobox-1) binding site does not alter activin A-stimulated promoter activity in homologous cells. Collectively, these and previous data suggest a model in which activins stimulate formation of FOXL2-SMAD2/3/4 complexes, which bind to the proximal murine Fshb promoter to stimulate its transcription. Within these complexes, FOXL2 and SMAD3 or SMAD4 bind to adjacent cis-elements, with SMAD3 brokering the physical interaction with FOXL2. Because this composite response element is highly conserved, this suggests a general mechanism whereby activins may regulate and/or modulate Fshb transcription in mammals. PMID:21622537

  1. Retinol Promotes In Vitro Growth of Proximal Colon Organoids through a Retinoic Acid-Independent Mechanism

    PubMed Central

    Nibe, Yoichi; Akiyama, Shintaro; Matsumoto, Yuka; Nozaki, Kengo; Fukuda, Masayoshi; Hayashi, Ayumi; Mizutani, Tomohiro; Oshima, Shigeru; Watanabe, Mamoru; Nakamura, Tetsuya

    2016-01-01

    Retinol (ROL), the alcohol form of vitamin A, is known to control cell fate decision of various types of stem cells in the form of its active metabolite, retinoic acid (RA). However, little is known about whether ROL has regulatory effects on colonic stem cells. We examined in this study the effect of ROL on the growth of murine normal colonic cells cultured as organoids. As genes involved in RA synthesis from ROL were differentially expressed along the length of the colon, we tested the effect of ROL on proximal and distal colon organoids separately. We found that organoid forming efficiency and the expression level of Lgr5, a marker gene for colonic stem cells were significantly enhanced by ROL in the proximal colon organoids, but not in the distal ones. Interestingly, neither retinaldehyde (RAL), an intermediate product of the ROL-RA pathway, nor RA exhibited growth promoting effects on the proximal colon organoids, suggesting that ROL-dependent growth enhancement in organoids involves an RA-independent mechanism. This was confirmed by the observation that an inhibitor for RA-mediated gene transcription did not abrogate the effect of ROL on organoids. This novel role of ROL in stem cell maintenance in the proximal colon provides insights into the mechanism of region-specific regulation for colonic stem cell maintenance. PMID:27564706

  2. Transactivation of the proximal promoter of human oxytocin gene by TR4 orphan receptor

    SciTech Connect

    Wang, C.-P.; Lee, Y.-F.; Chang, C.; Lee, H.-J. . E-mail: hjlee@mail.ndhu.edu.tw

    2006-12-08

    The human testicular receptor 4 (TR4) shares structural homology with members of the nuclear receptor superfamily. Some other members of this superfamily were able to regulate the transcriptional activity of the human oxytocin (OXT) promoter by binding to the first DR0 regulatory site. However, little investigation was conducted systematically in the study of the second dDR4 site of OXT proximal promoter, and the relationship between the first and the second sites of OXT promoter. Here, we demonstrated for the first time that TR4 could increase the proximal promoter activity of the human OXT gene via DR0, dDR4, and OXT (both DR0 and dDR4) elements, respectively. TR4 might induce OXT gene expression through the OXT element in a dose-dependent manner. However, there is no synergistic effect between DR0 and dDR4 elements during TR4 transactivation. Taken together, these results suggested that TR4 should be one of important regulators of OXT gene expression.

  3. Mechanisms and Developmental Roles of Promoter-proximal Pausing of RNA Polymerase II

    PubMed Central

    Robinson, Christine; Lowe, Matthew; Schwartz, Amanda; Kikyo, Nobuaki

    2016-01-01

    RNA polymerase II (Pol II) temporarily stops transcription after synthesizing 30–50 bases, and resumes elongation only after stimulations by various signaling molecules and developmental cues. This phenomenon, called promoter-proximal pausing, is observed in 10–50% of the entire genes from Drosophila embryos to human cells. Release of paused Pol II is primarily mediated by the activated form of positive transcription elongation factor b (P-TEFb) initially sequestered in the inhibitory 7SK small nuclear ribonucleoprotein (7SK snRNP) complex. Many proteins and RNAs have been discovered and studied in detail to explain the process of the pausing and release of Pol II in relation to P-TEFb. At the functional level, promoter-proximal pausing regulates genes involved in stimulus-response and development in Drosophila. In mammalian stem cell biology, pausing is important for proliferation and signaling in embryonic stem cells and the formation of induced pluripotent stem cells. Other than this, however, little is known about the biological significance of pausing in mammalian cell differentiation. Further study on pausing mechanisms as well as its functions will contribute to the development of stem cell biology and its clinical applications. PMID:27158559

  4. Sal-like protein 2 upregulates p16 expression through a proximal promoter element

    PubMed Central

    Wu, Zhenghua; Cheng, Kebin; Shi, Lidan; Li, Zheqi; Negi, Hema; Gao, Guangwei; Kamle, Suchitra; Li, Dawei

    2015-01-01

    Sal-like protein 2 (Sall2), a homeotic transcription factor, is a putative tumor suppressor. We have previously shown that Sall2 activates the transcription of tumor suppressor gene p21 and suppresses tumorigenesis through cell cycle inhibition and induction of apoptosis. To investigate additional Sall2-regulated downstream genes, we analyzed the differences in mRNA expression profiles with and without exogenously expressed Sall2. We identified 1616 Sall2-responsive genes through gene expression arrays. Promoter-reporter assays of p16INK4A and several other tumor-related genes indicated that the Sall2 regulation of these promoters was not significantly different between the two major forms of Sall2 with alternative exon 1 or exon 1A. Additional analysis showed that Sall2-induced p16 promoter activation was Sall2 dose-dependent. Deletion and site-directed mutagenesis of the p16 promoter identified a consensus Sall2 binding site (GGGTGGG) proximal to the p16 transcription start site and was critical for p16 promoter activation. Finally, to confirm the significance of Sall2-activated p16 expression in cell cycle regulation, we co-transfected the SKOV3 cells with a Sall2 expression construct and a p16 minigene and also co-transfected the ES-2 cells with a Sall2 expression construct and the siRNA against p16 for flow cytometry analysis. Our results showed that Sall2 enhanced the p16 minigene blocking of cell cycle progression and p16 knockdown with siRNA abolished most of the Sall2 inhibition of cell cycle progression. These findings indicate that Sall2 targets multiple cell cycle regulators, including p16, through their promoters, adding knowledge to the understanding of Sall2 and p16 gene regulation, and how Sall2 deregulation may promote cancer formation. PMID:25580951

  5. R loops regulate promoter-proximal chromatin architecture and cellular differentiation.

    PubMed

    Chen, Poshen B; Chen, Hsiuyi V; Acharya, Diwash; Rando, Oliver J; Fazzio, Thomas G

    2015-12-01

    Numerous chromatin-remodeling factors are regulated by interactions with RNA, although the contexts and functions of RNA binding are poorly understood. Here we show that R loops, RNA-DNA hybrids consisting of nascent transcripts hybridized to template DNA, modulate the binding of two key chromatin-regulatory complexes, Tip60-p400 and polycomb repressive complex 2 (PRC2) in mouse embryonic stem cells (ESCs). Like PRC2, the Tip60-p400 histone acetyltransferase complex binds to nascent transcripts; however, transcription promotes chromatin binding of Tip60-p400 but not PRC2. Interestingly, we observed higher Tip60-p400 and lower PRC2 levels at genes marked by promoter-proximal R loops. Furthermore, disruption of R loops broadly decreased Tip60-p400 occupancy and increased PRC2 occupancy genome wide. In agreement with these alterations, ESCs partially depleted of R loops exhibited impaired differentiation. These results show that R loops act both positively and negatively in modulating the recruitment of key pluripotency regulators. PMID:26551076

  6. R-loops regulate promoter-proximal chromatin architecture and cellular differentiation

    PubMed Central

    Chen, Poshen B.; Chen, Hsiuyi V.; Acharya, Diwash; Rando, Oliver J.; Fazzio, Thomas G.

    2015-01-01

    Numerous chromatin-remodeling factors are regulated by interactions with RNA, although the contexts and functions of RNA binding are poorly understood. Here we show that R-loops, RNA:DNA hybrids consisting of nascent transcripts hybridized to template DNA, modulate the binding of two key chromatin regulatory complexes, Tip60–p400 and polycomb repressive complex 2 (PRC2) in mouse embryonic stem cells (ESCs). Like PRC2, the Tip60–p400 histone acetyltransferase complex binds to nascent transcripts, but unlike PRC2, transcription promotes chromatin binding by Tip60–p400. Interestingly, we observed higher Tip60–p400 and lower PRC2 levels at genes marked by promoter-proximal R-loops. Furthermore, disruption of R-loops broadly reduced Tip60–p400 and increased PRC2 occupancy genome-wide. Consistent with these alterations, ESCs with reduced R-loops exhibited impaired differentiation. These results show that R-loops act both positively and negatively to modulate the recruitment of key pluripotency regulators. PMID:26551076

  7. Distal apolipoprotein C-III regulatory elements F to J act as a general modular enhancer for proximal promoters that contain hormone response elements. Synergism between hepatic nuclear factor-4 molecules bound to the proximal promoter and distal enhancer sites.

    PubMed

    Kardassis, D; Tzameli, I; Hadzopoulou-Cladaras, M; Talianidis, I; Zannis, V

    1997-01-01

    Transient transfection assays have shown that the distal apoC-III promoter segments that contain the regulatory elements F to J enhance the strength of the tandemly linked proximal apoA-I promoter 5- to 13-fold in hepatic (HepG2) cells. Activation in intestinal (CaCo-2) cells to levels comparable to those obtained in HepG2 cells requires a larger apoA-I promoter sequence that extends to nucleotide -1500 as well as the presence of hepatic nuclear factor-4 (HNF-4). The distal apoC-III regulatory elements can also enhance 4- to 8-fold the strength of the heterologous apoB promoter in HepG2 and CaCo-2 cells. Finally, these elements in the presence of HNF-4 enhance 14.5- to 18.5-fold the strength of the minimal adenovirus major late promoter linked to two copies of the hormone response element (HRE) AID of apoA-I in both HepG2 and CaCo-2 cells. In vitro mutagenesis of the promoter/enhancer cluster established that the enhancer activity is lost by a mutation in the HRE present in the 3' end of the regulatory element I (-736 to -714) and is reduced significantly by point mutations or deletions in one or more of the regulatory elements F to J of the apoC-III enhancer. The enhancer activity also requires the HREs of the proximal apoA-I promoter. The apoC-III enhancer can also restore the activity of the proximal apoA-I and apoB promoters that have been inactivated by mutations in CCAAT/enhancers binding protein binding sites, indicating that C/EBP may not participate in the synergistic activation of the promoter/enhancer cluster. The findings suggest that the regulatory elements F to J of the apoC-III promoter act as a general modular enhancer that can potentiate the strength of proximal promoters that contain HREs. Such potentiation in the HepG2 cells can be accounted for by synergistic interactions between HNF-4 or other nuclear hormone receptors bound to the proximal and distal HREs and SP1 or other factors bound to the apoC-III enhancer. Additional factors may be

  8. Hyperbaric Oxygen Promotes Proximal Bone Regeneration and Organized Collagen Composition during Digit Regeneration

    PubMed Central

    Sammarco, Mimi C.; Simkin, Jennifer; Cammack, Alexander J.; Fassler, Danielle; Gossmann, Alexej; Marrero, Luis; Lacey, Michelle; Van Meter, Keith; Muneoka, Ken

    2015-01-01

    Oxygen is critical for optimal bone regeneration. While axolotls and salamanders have retained the ability to regenerate whole limbs, mammalian regeneration is restricted to the distal tip of the digit (P3) in mice, primates, and humans. Our previous study revealed the oxygen microenvironment during regeneration is dynamic and temporally influential in building and degrading bone. Given that regeneration is dependent on a dynamic and changing oxygen environment, a better understanding of the effects of oxygen during wounding, scarring, and regeneration, and better ways to artificially generate both hypoxic and oxygen replete microenvironments are essential to promote regeneration beyond wounding or scarring. To explore the influence of increased oxygen on digit regeneration in vivo daily treatments of hyperbaric oxygen were administered to mice during all phases of the entire regenerative process. Micro-Computed Tomography (μCT) and histological analysis showed that the daily application of hyperbaric oxygen elicited the same enhanced bone degradation response as two individual pulses of oxygen applied during the blastema phase. We expand past these findings to show histologically that the continuous application of hyperbaric oxygen during digit regeneration results in delayed blastema formation at a much more proximal location after amputation, and the deposition of better organized collagen fibers during bone formation. The application of sustained hyperbaric oxygen also delays wound closure and enhances bone degradation after digit amputation. Thus, hyperbaric oxygen shows the potential for positive influential control on the various phases of an epimorphic regenerative response. PMID:26452224

  9. Multiple P-TEFbs cooperatively regulate the release of promoter-proximally paused RNA polymerase II.

    PubMed

    Lu, Xiaodong; Zhu, Xinxing; Li, You; Liu, Min; Yu, Bin; Wang, Yu; Rao, Muhua; Yang, Haiyang; Zhou, Kai; Wang, Yao; Chen, Yanheng; Chen, Meihua; Zhuang, Songkuan; Chen, Lin-Feng; Liu, Runzhong; Chen, Ruichuan

    2016-08-19

    The association of DSIF and NELF with initiated RNA Polymerase II (Pol II) is the general mechanism for inducing promoter-proximal pausing of Pol II. However, it remains largely unclear how the paused Pol II is released in response to stimulation. Here, we show that the release of the paused Pol II is cooperatively regulated by multiple P-TEFbs which are recruited by bromodomain-containing protein Brd4 and super elongation complex (SEC) via different recruitment mechanisms. Upon stimulation, Brd4 recruits P-TEFb to Spt5/DSIF via a recruitment pathway consisting of Med1, Med23 and Tat-SF1, whereas SEC recruits P-TEFb to NELF-A and NELF-E via Paf1c and Med26, respectively. P-TEFb-mediated phosphorylation of Spt5, NELF-A and NELF-E results in the dissociation of NELF from Pol II, thereby transiting transcription from pausing to elongation. Additionally, we demonstrate that P-TEFb-mediated Ser2 phosphorylation of Pol II is dispensable for pause release. Therefore, our studies reveal a co-regulatory mechanism of Brd4 and SEC in modulating the transcriptional pause release by recruiting multiple P-TEFbs via a Mediator- and Paf1c-coordinated recruitment network. PMID:27353326

  10. The NHERF2 sequence adjacent and upstream of the ERM-binding domain affects NHERF2-ezrin binding and dexamethasone stimulated NHE3 activity.

    PubMed

    Yang, Jianbo; Sarker, Rafiquel; Singh, Varsha; Sarker, Prateeti; Yin, Jianyi; Chen, Tian-E; Chaerkady, Raghothama; Li, Xuhang; Tse, C Ming; Donowitz, Mark

    2015-08-15

    In the brush border of intestinal and kidney epithelial cells, scaffolding proteins ezrin, Na(+)-H(+) exchanger regulatory factor (NHERF)1 and NHERF2 play important roles in linking transmembrane proteins to the cytoskeleton and assembling signalling regulatory complexes. The last 30 carboxyl residues of NHERF1 and NHERF2 form the EBDs [ezrin, radixin and moesin (ERM)-binding domain]. The current study found that NHERF1/2 contain an ERM-binding regulatory sequence (EBRS), which facilitates the interaction between the EBD and ezrin. The EBRSs are located within 24 and 19 residues immediately upstream of EBDs for NHERF1 and NHERF2 respectively. In OK (opossum kidney) epithelial cells, EBRSs are necessary along with the EBD to distribute NHERF1 and NHERF2 exclusively to the apical domain. Furthermore, phosphorylation of Ser(303) located in the EBRS of NHERF2, decreases the binding affinity for ezrin, dislocates apical NHERF2 into the cytosol and increases the NHERF2 microvillar mobility rate. Moreover, increased phosphorylation of Ser(303) was functionally significant preventing acute stimulation of NHE3 (Na(+)-H(+) exchanger 3) activity by dexamethasone. PMID:26251448

  11. The NHERF2 sequence adjacent and upstream of the ERM-binding domain affects NHERF2–ezrin binding and dexamethasone stimulated NHE3 activity

    PubMed Central

    Yang, Jianbo; Sarker, Rafiquel; Singh, Varsha; Sarker, Prateeti; Yin, Jianyi; Chen, Tian-E; Chaerkady, Raghothama; Li, Xuhang; Tse, C. Ming; Donowitz, Mark

    2015-01-01

    In the brush border of intestinal and kidney epithelial cells, scaffolding proteins ezrin, Na+-H+ exchanger regulatory factor (NHERF)1 and NHERF2 play important roles in linking transmembrane proteins to the cytoskeleton and assembling signalling regulatory complexes. The last 30 carboxyl residues of NHERF1 and NHERF2 form the EBDs [ezrin, radixin and moesin (ERM)-binding domain]. The current study found that NHERF1/2 contain an ERM-binding regulatory sequence (EBRS), which facilitates the interaction between the EBD and ezrin. The EBRSs are located within 24 and 19 residues immediately upstream of EBDs for NHERF1 and NHERF2 respectively. In OK (opossum kidney) epithelial cells, EBRSs are necessary along with the EBD to distribute NHERF1 and NHERF2 exclusively to the apical domain. Furthermore, phosphorylation of Ser303 located in the EBRS of NHERF2, decreases the binding affinity for ezrin, dislocates apical NHERF2 into the cytosol and increases the NHERF2 microvillar mobility rate. Moreover, increased phosphorylation of Ser303 was functionally significant preventing acute stimulation of NHE3 (Na+-H+ exchanger 3) activity by dexamethasone. PMID:26251448

  12. Trichostatin A, a histone deacetylase inhibitor stimulate CYP3A4 proximal promoter activity in Hepa-I cells.

    PubMed

    Ahn, Mee Ryung; Kim, Dae-Kee; Sheen, Yhun Yhong

    2004-04-01

    Cytochrome P450 3A4 (CYP3A4) is the most abundant CYPs in human liver, comprising approximately 30% of the total liver CYPs contents and is involved in the metabolism of more than 60% of currently used therapeutic drugs. However, the molecular mechanisms underlying regulation of CYP3A4 gene expression have not been understood. Thus, this study has been carried out to gain the insight of the molecular mechanism of CYP3A4 gene expression, investigating if the histone deacetylation is involved in the regulation of CYP3A4 gene expression by proximal promoter. Also SXR was investigated to see if they were involved in the regulation of CYP3A4 proximal promoter activity. Hepa-I cells were transfected with a plasmid containing approximately 1 kb of the human CYP3A4 proximal promoter region (863 to +64 bp) cloned in front of a reporter gene, luciferase, in the presence or absence of SXR. Transfected cells were treated with CYP3A4 inducers such as rifampicin, PCN and RU 486, in order to examine the regulation of CYP3A4 gene expression in the presence or absence of trichostatin A (TSA). In Hepa-I cells, CYP3A4 inducers increased modestly the luciferase activity when TSA was co-treated, but this increment was not enhanced by SXR cotransfection. Taken together, these results indicated that the inhibition of histone deacetylation was required to SXR-mediated increase in CYP3A4 proximal promoter region when rifampicin, or PCN was treated. Further a trans-activation by SXR may demand other species-specific transcription factors. PMID:15180307

  13. Azilsartan Improves Salt Sensitivity by Modulating the Proximal Tubular Na+-H+ Exchanger-3 in Mice

    PubMed Central

    Hatanaka, Masaki; Kaimori, Jun-Ya; Yamamoto, Satoko; Matsui, Isao; Hamano, Takayuki; Takabatake, Yoshitsugu; Ecelbarger, Carolyn M.; Takahara, Shiro; Isaka, Yoshitaka; Rakugi, Hiromi

    2016-01-01

    A potent angiotensin II type-1 receptor blocker, azilsartan, has been reported to reduce blood pressure more effectively than candesartan. Interestingly, azilsartan can also restore the circadian rhythm of blood pressure. We hypothesized that azilsartan could also improve salt sensitivity; thus, we examined the effect of azilsartan on sodium handling in renal tubules. Subtotal nephrectomized C57BL/6 mice received azilsartan (1.0 mg/kg/day), candesartan (0.3 mg/kg/day), or vehicle via the oral route in conjunction with a normal- (0.3%) or high-salt (8.0%) diet. Two weeks later, the azilsartan group showed significantly lower blood pressure during the light period than the candesartan and vehicle groups (azilsartan: 103.1 ± 1.0; candesartan: 111.7 ± 2.7; vehicle: 125.5 ± 2.5 mmHg; P < 0.05; azilsartan or candesartan vs. vehicle). The azilsartan group also showed higher urinary fractional excretion of sodium during the dark period than the candesartan and vehicle groups (azilsartan: 21.37 ± 3.69%; candesartan: 14.17 ± 1.42%; vehicle: 13.85 ± 5.30%; P < 0.05 azilsartan vs. candesartan or vehicle). A pressure—natriuresis curve demonstrated that azilsartan treatment restored salt sensitivity. Immunofluorescence and western blotting showed lower levels of Na+-H+ exchanger-3 (NHE3) protein (the major sodium transporter in renal proximal tubules) in the azilsartan group, but not in the candesartan or vehicle groups. However, azilsartan did not affect NHE3 transcription levels. Interestingly, we did not observe increased expression of downstream sodium transporters, which would have compensated for the increased flow of sodium and water due to non-absorption by NHE3. We also confirmed the mechanism stated above using cultured opossum kidney proximal tubular cells. Results revealed that a proteasomal inhibitor (but not a lysosomal inhibitor) blocked the azilsartan-induced decrease in NHE3 protein expression, suggesting that azilsartan increases NHE3 ubiquitination. In

  14. Azilsartan Improves Salt Sensitivity by Modulating the Proximal Tubular Na+-H+ Exchanger-3 in Mice.

    PubMed

    Hatanaka, Masaki; Kaimori, Jun-Ya; Yamamoto, Satoko; Matsui, Isao; Hamano, Takayuki; Takabatake, Yoshitsugu; Ecelbarger, Carolyn M; Takahara, Shiro; Isaka, Yoshitaka; Rakugi, Hiromi

    2016-01-01

    A potent angiotensin II type-1 receptor blocker, azilsartan, has been reported to reduce blood pressure more effectively than candesartan. Interestingly, azilsartan can also restore the circadian rhythm of blood pressure. We hypothesized that azilsartan could also improve salt sensitivity; thus, we examined the effect of azilsartan on sodium handling in renal tubules. Subtotal nephrectomized C57BL/6 mice received azilsartan (1.0 mg/kg/day), candesartan (0.3 mg/kg/day), or vehicle via the oral route in conjunction with a normal- (0.3%) or high-salt (8.0%) diet. Two weeks later, the azilsartan group showed significantly lower blood pressure during the light period than the candesartan and vehicle groups (azilsartan: 103.1 ± 1.0; candesartan: 111.7 ± 2.7; vehicle: 125.5 ± 2.5 mmHg; P < 0.05; azilsartan or candesartan vs. vehicle). The azilsartan group also showed higher urinary fractional excretion of sodium during the dark period than the candesartan and vehicle groups (azilsartan: 21.37 ± 3.69%; candesartan: 14.17 ± 1.42%; vehicle: 13.85 ± 5.30%; P < 0.05 azilsartan vs. candesartan or vehicle). A pressure-natriuresis curve demonstrated that azilsartan treatment restored salt sensitivity. Immunofluorescence and western blotting showed lower levels of Na+-H+ exchanger-3 (NHE3) protein (the major sodium transporter in renal proximal tubules) in the azilsartan group, but not in the candesartan or vehicle groups. However, azilsartan did not affect NHE3 transcription levels. Interestingly, we did not observe increased expression of downstream sodium transporters, which would have compensated for the increased flow of sodium and water due to non-absorption by NHE3. We also confirmed the mechanism stated above using cultured opossum kidney proximal tubular cells. Results revealed that a proteasomal inhibitor (but not a lysosomal inhibitor) blocked the azilsartan-induced decrease in NHE3 protein expression, suggesting that azilsartan increases NHE3 ubiquitination. In

  15. Profiles of embryonic nuclear protein binding to the proximal promoter region of the soybean β-conglycinin α subunit gene.

    PubMed

    Yoshino, M; Tsutsumi, K; Kanazawa, A

    2015-01-01

    β-Conglycinin, a major component of seed storage protein in soybean, comprises three subunits: α, α' and β. The expression of genes for these subunits is strictly controlled during embryogenesis. The proximal promoter region up to 245 bp upstream of the transcription start site of the α subunit gene sufficiently confers spatial and temporal control of transcription in embryos. Here, the binding profile of nuclear proteins in the proximal promoter region of the α subunit gene was analysed. DNase I footprinting analysis indicated binding of proteins to the RY element and DNA regions including box I, a region conserved in cognate gene promoters. An electrophoretic mobility shift assay (EMSA) using different portions of box I as a probe revealed that multiple portions of box I bind to nuclear proteins. In addition, an EMSA using nuclear proteins extracted from embryos at different developmental stages indicated that the levels of major DNA-protein complexes on box I increased during embryo maturation. These results are consistent with the notion that box I is important for the transcriptional control of seed storage protein genes. Furthermore, the present data suggest that nuclear proteins bind to novel motifs in box I including 5'-TCAATT-3' rather than to predicted cis-regulatory elements. PMID:24943483

  16. Hypomethylation of proximal CpG motif of interleukin-10 promoter regulates its expression in human rheumatoid arthritis

    PubMed Central

    Fu, Li-hong; Ma, Chun-ling; Cong, Bin; Li, Shu-jin; Chen, Hai-ying; Zhang, Jing-ge

    2011-01-01

    Aim: The promoter of human interleukin-10 (IL10), a cytokine crucial for suppressing inflammation and regulating immune responses, contains an interspecies-conserved sequence with CpG motifs. The aim of this study was to investigate whether methylation of CpG motifs could regulate the expression of IL10 in rheumatoid arthritis (RA). Methods: Bioinformatic analysis was conducted to identify the interspecies-conserved sequence in human, macaque and mouse IL10 genes. Peripheral blood mononuclear cells (PBMCs) from 20 RA patients and 20 health controls were collected. The PBMCs from 6 patients were cultured in the presence or absence of 5-azacytidine (5 μmol/L). The mRNA and protein levels of IL10 were examined using RT-PCR and ELISA, respectively. The methylation of CpGs in the IL10 promoter was determined by pyrosequencing. Chromatin immunoprecipitation (ChIP) assays were performed to detect the cyclic AMP response element-binding protein (CREB)-DNA interactions. Results: One interspecies-conserved sequence was found within the IL10 promoter. The upstream CpGs at −408, −387, −385, and −355 bp were hypermethylated in PBMCs from both the RA patients and healthy controls. In contrast, the proximal CpG at −145 was hypomethylated to much more extent in the RA patients than in the healthy controls (P=0.016), which was correlated with higher IL10 mRNA and serum levels. In the 5-azacytidine-treated PBMCs, the CpG motifs were demethylated, and the expression levels of IL10 mRNA and protein was significantly increased. CHIP assays revealed increased phospho-CREB binding to the IL10 promoter. Conclusion: The methylation of the proximal CpGs in the IL10 promoter may regulate gene transcription in RA. PMID:21986577

  17. Cloning of mouse telomerase reverse transcriptase gene promoter and identification of proximal core promoter sequences essential for the expression of transgenes in cancer cells.

    PubMed

    Si, Shao-Yan; Song, Shu-Jun; Zhang, Jian-Zhong; Liu, Jun-Li; Liang, Shuang; Feng, Kai; Zhao, Gang; Tan, Xiao-Qing

    2011-08-01

    Telomerase is a ribonucleoprotein complex, whose function is to add motif-specific nucleotides to the end of chromosomes. Telomerase consists of three major subunits, the telomerase RNA template (hTR), the telomerase-associated protein (TEP1) and telomerase reverse transcriptase (TERT). TERT is the most important component responsible for the catalytic activity of telomerase and a rate-limiting determinant of the activity. Telomerase activities were at high levels in approximately 90% of mouse cancers or tumor-derived cell lines through TERT transcriptional up-regulation. Unlike human telomerase, telomerase activity exists in colon, liver, ovary and testis but not in brain, heart, stomach and muscle in normal mouse tissues. In this study, we prepared 5' truncations of 1086 bp fragments upstream of the initiating ATG codon of the mTERT gene to construct luciferase reporter gene plasmids, and transfected these plasmids into a normal mouse cell line and several cancer lines to identify the core promoter region essential for transcriptional activation in cancer cells by a luciferase assay. We constructed a eukaryotic expression vector of membrane-expressing staphylococcal endotoxin A (SEA) gene driven by the core promoter region of the mTERT gene and observed if the core promoter region could express the SEA gene in these cancer cells, but not in normal cells following transfection with the construct. The results showed that the transcriptional activities of each fragment of the mTERT gene promoter in the cancer cell lines Hepa1-6, B16 and CT26 were higher than those in NIH3T3 cells, and the proximal 333-bp fragment was the core promoter of the mTERT gene in the cancer cells. The proximal 333-bp fragment was able to make the SEA express on the surface of the cancer cells, but not in NIH3T3 cells. It provides a foundation for cancer targeting gene therapy by using the mTERT gene promoter. PMID:21567104

  18. Evolution of the C4 phosphoenolpyruvate carboxylase promoter of the C4 species Flaveria trinervia: the role of the proximal promoter region

    PubMed Central

    Engelmann, Sascha; Zogel, Corinna; Koczor, Maria; Schlue, Ute; Streubel, Monika; Westhoff, Peter

    2008-01-01

    Background The key enzymes of photosynthetic carbon assimilation in C4 plants have evolved independently several times from C3 isoforms that were present in the C3 ancestral species. The C4 isoform of phosphoenolpyruvate carboxylase (PEPC), the primary CO2-fixing enzyme of the C4 cycle, is specifically expressed at high levels in mesophyll cells of the leaves of C4 species. We are interested in understanding the molecular changes that are responsible for the evolution of this C4-characteristic PEPC expression pattern, and we are using the genus Flaveria (Asteraceae) as a model system. It is known that cis-regulatory sequences for mesophyll-specific expression of the ppcA1 gene of F. trinervia (C4) are located within a distal promoter region (DR). Results In this study we focus on the proximal region (PR) of the ppcA1 promoter of F. trinervia and present an analysis of its function in establishing a C4-specific expression pattern. We demonstrate that the PR harbours cis-regulatory determinants which account for high levels of PEPC expression in the leaf. Our results further suggest that an intron in the 5' untranslated leader region of the PR is not essential for the control of ppcA1 gene expression. Conclusion The allocation of cis-regulatory elements for enhanced expression levels to the proximal region of the ppcA1 promoter provides further insight into the regulation of PEPC expression in C4 leaves. PMID:18208593

  19. Interaction of basal positive and negative transcription elements controls repression of the proximal rat prolactin promoter in nonpituitary cells.

    PubMed Central

    Jackson, S M; Keech, C A; Williamson, D J; Gutierrez-Hartmann, A

    1992-01-01

    The proximal rat prolactin (rPRL) promoter contains three cell-specific elements, designated footprints I, III, and IV, which restrict rPRL gene expression to anterior pituitary lactotroph cells. Footprint II (-130 to -120) binds a factor, which we have termed F2F, present in pituitary and nonpituitary cell types. Here we demonstrate that a key role of the footprint II site is to inhibit rPRL promoter activity in nonpituitary cells, specifically, by interfering with the basal activating function of a vicinal element. Gene transfer analysis revealed 20-fold activation of the rPRL promoter in nonpituitary cell types when footprint II was either deleted or specifically mutated. Similar activation of the intact rPRL promoter was obtained by in vivo F2F titration studies. In GH4 rat pituitary cells, the footprint II inhibitory activity was masked by the redundant, positively acting cell-specific elements and was inhibitory only if the two upstream sites, footprints III and IV, were deleted. Deletion of the -112 to -80 region in the footprint II site-specific mutant background resulted in complete loss of rPRL promoter activity in both pituitary and nonpituitary cell types, mapping a basal activating element that is operative irrespective of cell type to this region. While the basal activating element imparted an activating function in a heterologous promoter assay, the footprint II sequence did not display any inherent repressor function and actually induced several minimal heterologous promoters. However, the inhibitory activity of the footprint II site was detected only if it was in context with the basal activating element. These data underscore the importance of ubiquitous activating and inhibitory factors in establishing cell-specific gene expression and further emphasize the complexity of the molecular mechanisms which restrict gene expression to specific cell types. We provide a novel paradigm to study rPRL promoter function and hormone responsiveness

  20. Analysis of the AHR gene proximal promoter GGGGC-repeat polymorphism in lung, breast, and colon cancer

    SciTech Connect

    Spink, Barbara C.; Bloom, Michael S.; Wu, Susan; Sell, Stewart; Schneider, Erasmus; Ding, Xinxin; Spink, David C.

    2015-01-01

    The aryl hydrocarbon receptor (AhR) regulates expression of numerous genes, including those of the CYP1 gene family. With the goal of determining factors that control AHR gene expression, our studies are focused on the role of the short tandem repeat polymorphism, (GGGGC){sub n}, located in the proximal promoter of the human AHR gene. When luciferase constructs containing varying GGGGC repeats were transfected into cancer cell lines derived from the lung, colon, and breast, the number of GGGGC repeats affected AHR promoter activity. The number of GGGGC repeats was determined in DNA from 327 humans and from 38 samples representing 5 species of non-human primates. In chimpanzees and 3 species of macaques, only (GGGGC){sub 2} alleles were observed; however, in western gorilla, (GGGGC){sub n} alleles with n = 2, 4, 5, 6, 7, and 8 were identified. In all human populations examined, the frequency of (GGGGC){sub n} was n = 4 > 5 ≫ 2, 6. When frequencies of the (GGGGC){sub n} alleles in DNA from patients with lung, colon, or breast cancer were evaluated, the occurrence of (GGGGC){sub 2} was found to be 8-fold more frequent among lung cancer patients in comparison with its incidence in the general population, as represented by New York State neonates. Analysis of matched tumor and non-tumor DNA samples from the same individuals provided no evidence of microsatellite instability. These studies indicate that the (GGGGC){sub n} short tandem repeats are inherited, and that the (GGGGC){sub 2} allele in the AHR proximal promoter region should be further investigated with regard to its potential association with lung cancer susceptibility. - Highlights: • The AHR proximal promoter contains a polymorphism, (GGGGC){sub n}, where n = 4 > 5 ≫ 2, 6 • Matched tumor and non-tumor DNA did not show (GGGGC){sub n} microsatellite instability • AHR promoter activity of a construct with (GGGGC){sub 2} was lower than that of (GGGGC){sub 4} • The frequency of (GGGGC){sub 2} in lung

  1. Contribution of a Nuclear Factor-κB Binding Site to Human Angiotensinogen Promoter Activity in Renal Proximal Tubular Cells

    PubMed Central

    Acres, Omar W.; Satou, Ryousuke; Navar, L. Gabriel; Kobori, Hiroyuki

    2011-01-01

    Intrarenal angiotensinogen (AGT) is expressed highly in renal proximal tubular cells (RPTCs) and contributes to the regulation of intrarenal angiotensin II levels. Inhibition of nuclear factor (NF)-κB suppressed human (h)AGT expression in human RPTCs. However, the presence and localization of an NF-κB binding site in the hAGT promoter region have not been determined. Therefore, this study was performed to demonstrate that an NF-κB binding site in the hAGT promoter region contributes to hAGT promoter activity in human RPTCs. The hAGT promoter region was cloned from −4358 to +122 and deletion analysis was performed. A possible NF-κB binding site was removed from the hAGT promoter region (M1) and mutated (M2). Human RPTCs were transfected, and hAGT promoter activity was determined by luciferase assay. The identity of DNA binding proteins from binding assays were determined by Western blot. Progressive 5′-end deletions demonstrated removal of a distal promoter element in hAGT_−2414/+122 reduced promoter activity (0.61±0.12, ratio to hAGT_−4358/+122). Inhibition of NF-κB suppressed promoter activity in hAGT_−4358/+122 (0.51±0.14, ratio to control) and hAGT_−3681/+122 (0.48±0.06, ratio to control) but not in the construct without the NF-κB binding site. Promoter activity was reduced in the domain mutants M1 (0.57±0.08, ratio to hAGT_−4358/+122) and M2 (0.61±0.16, ratio to hAGT_−4358/+122). DNA binding levels of NF-κB protein were reduced in M1. These data demonstrate the functional importance of an NF-κB binding site in the hAGT promoter region, which contributes to hAGT promoter activity in human RPTCs. PMID:21282554

  2. Pollen specificity elements reside in 30 bp of the proximal promoters of two pollen-expressed genes.

    PubMed

    Eyal, Y; Curie, C; McCormick, S

    1995-03-01

    Functional analyses previously identified minimal promoter regions required for maintaining high-level expression of the late anther tomato LAT52 and LAT59 genes in tomato pollen. Here, we now define elements that direct pollen specificity. We used a transient assay system consisting of two cell types that differentially express the LAT genes and both "loss-of-function" and "gain-of-function" approaches. Linker substitution mutants analyzed in the transient assay and in transgenic plants identified 30-bp proximal promoter regions of LAT52 and LAT59 that are essential for their expression in pollen and that confer pollen specificity when fused to the heterologous cauliflower mosaic virus 35S core promoter. In vivo competition experiments demonstrated that a common trans-acting factor interacts with the pollen specificity region of both LAT gene promoters and suggested that a common mechanism regulates their coordinate expression. Adjacent upstream elements, the 52/56 box in LAT52 and the 56/59 box in LAT59, are involved in modulating the level of expression in pollen. The 52/56 box may be a target for the binding of a member of the GT-1 transcription factor family. PMID:7734969

  3. Pollen specificity elements reside in 30 bp of the proximal promoters of two pollen-expressed genes.

    PubMed Central

    Eyal, Y; Curie, C; McCormick, S

    1995-01-01

    Functional analyses previously identified minimal promoter regions required for maintaining high-level expression of the late anther tomato LAT52 and LAT59 genes in tomato pollen. Here, we now define elements that direct pollen specificity. We used a transient assay system consisting of two cell types that differentially express the LAT genes and both "loss-of-function" and "gain-of-function" approaches. Linker substitution mutants analyzed in the transient assay and in transgenic plants identified 30-bp proximal promoter regions of LAT52 and LAT59 that are essential for their expression in pollen and that confer pollen specificity when fused to the heterologous cauliflower mosaic virus 35S core promoter. In vivo competition experiments demonstrated that a common trans-acting factor interacts with the pollen specificity region of both LAT gene promoters and suggested that a common mechanism regulates their coordinate expression. Adjacent upstream elements, the 52/56 box in LAT52 and the 56/59 box in LAT59, are involved in modulating the level of expression in pollen. The 52/56 box may be a target for the binding of a member of the GT-1 transcription factor family. PMID:7734969

  4. Promoting Metapragmatic Development through Assessment in the Zone of Proximal Development

    ERIC Educational Resources Information Center

    van Compernolle, Remi A.; Kinginger, Celeste

    2013-01-01

    The assessment of second language (L2) pragmatic competence typically involves questionnaires, such as discourse completion tasks. This article describes a novel approach to using questionnaires to assess L2 metapragmatic capacities while simultaneously promoting their development: engaging learners in cooperative interaction as they complete the…

  5. γ-Secretase inhibition promotes fibrotic effects of albumin in proximal tubular epithelial cells

    PubMed Central

    Slattery, C; Jang, Y; Kruger, W A; Hryciw, D H; Lee, A; Poronnik, P

    2013-01-01

    Background and Purpose Albuminuria is an important biomarker of renal dysfunction and is a major mediator of renal damage and fibrosis during kidney disease. The mechanisms underlying albumin-induced renal fibrosis remain unclear. There has been significant interest in γ-secretase activity in tubular epithelial cells in recent times; however, its potential role in albumin-induced fibrosis has not been investigated. Experimental Approach The primary aim of this study was to examine the role of γ-secretase in albumin-induced fibrotic effects in proximal tubular cells. The effects of increasing albumin concentrations on fibrosis indicators and mediators in the human HK-2 cell line were examined in the presence and absence of a γ-secretase inhibitor, compound E. Key Results Treatment with albumin resulted in a number of pro-fibrotic effects, including up-regulation of fibronectin, TGF-β1 and the EGF-R. Interestingly, similar effects were observed in response to treatment with the γ-secretase inhibitor, compound E. Co-treatment of cells with albumin and an EGF-R inhibitor, AG-1478, resulted in significant inhibition of the observed pro-fibrotic effects, suggesting a major role for the EGF-R in albumin-induced fibrotic events. Albumin-induced effects on the EGF-R appeared to be mediated through inhibition of γ-secretase activity and were dependent on ERK-MAPK signalling. Conclusions and Implications These results provide novel insights into the mechanisms of albumin-induced fibrotic effects in tubular epithelial cells, suggesting important roles for the γ-secretase and the EGF-R. These results suggest that the proposed use of γ-secretase inhibitors as anti-fibrotic agents requires further investigation. PMID:23594166

  6. Functional characterization of ETV6 and ETV6/CBFA2 in the regulation of the MCSFR proximal promoter.

    PubMed

    Fears, S; Gavin, M; Zhang, D E; Hetherington, C; Ben-David, Y; Rowley, J D; Nucifora, G

    1997-03-01

    The ETV6/CBFA2 (TEL/AML1) fusion gene occurs as a result of the chromosome translocation t(12;21)(p13;q22) in up to 30% of children diagnosed with B cell precursor (cd10+, cd19+) acute lymphoblastic leukemia. Leukemic cells that have acquired the t(12;21) usually demonstrate loss of the remaining normal ETV6 (TEL) allele. Using reporter gene assays we have functionally characterized both the normal ETV6 and ETV6/CBFA2 fusion proteins in the regulation of the MCSFR proximal promoter. Neither ETV6 or ETV6/CBFA2 has any significant, detectable effect on the promoter by itself. However, both ETV6 and ETV6/CBFA2 inhibit the activation of the promoter by CBFA2B(AML1B) and C/EBPa. We have shown that a 29-bp region of the MCSFR promoter containing the binding sites for CBFA2B and C/EBPa is sufficient for the inhibition by ETV6 and ETV6/CBFA2. Mutational analysis of the MCSFR promoter revealed that binding of both CBFA2B and C/EBPa to their respective sites is necessary for the inhibition by ETV6 and ETV6/CBFA2. Deletion of the helix-loop-helix (HLH) region from the cDNAs of ETV6 and ETV6/CBFA2 decreased but did not completely abrogate the ability of either construct to inhibit promoter activation. We also found that the ETS DNA binding region of ETV6 is necessary for inhibition of the promoter. Addition of ETS1 and FLI1, two ETS family members that have homology in the 5' HLH region, but not Spi1, an ETS family member without the 5' HLH region, also inhibited reporter gene expression. Our data show that the inhibition mediated by ETV6 and ETV6/CBFA2, in the context of the MCSFR promoter, depend on interactions with other proteins, not just CBFA2B. Our results also indicate that the transactivation characteristics of ETV6/CBFA2 are a combination of positive and negative regulatory properties. PMID:9050885

  7. NELF and GAGA Factor Are Linked to Promoter-Proximal Pausing at Many Genes in Drosophila▿ †

    PubMed Central

    Lee, Chanhyo; Li, Xiaoyong; Hechmer, Aaron; Eisen, Michael; Biggin, Mark D.; Venters, Bryan J.; Jiang, Cizhong; Li, Jian; Pugh, B. Franklin; Gilmour, David S.

    2008-01-01

    Recent analyses of RNA polymerase II (Pol II) revealed that Pol II is concentrated at the promoters of many active and inactive genes. NELF causes Pol II to pause in the promoter-proximal region of the hsp70 gene in Drosophila melanogaster. In this study, genome-wide location analysis (chromatin immunoprecipitation-microarray chip [ChIP-chip] analysis) revealed that NELF is concentrated at the 5′ ends of 2,111 genes in Drosophila cells. Permanganate genomic footprinting was used to determine if paused Pol II colocalized with NELF. Forty-six of 56 genes with NELF were found to have paused Pol II. Pol II pauses 30 to 50 nucleotides downstream from transcription start sites. Analysis of DNA sequences in the vicinity of paused Pol II identified a conserved DNA sequence that probably associates with TFIID but detected no evidence of RNA secondary structures or other conserved sequences that might directly control elongation. ChIP-chip experiments indicate that GAGA factor associates with 39% of the genes that have NELF. Surprisingly, NELF associates with almost one-half of the most highly expressed genes, indicating that NELF is not necessarily a repressor of gene expression. NELF-associated pausing of Pol II might be an obligatory but sometimes transient checkpoint during the transcription cycle. PMID:18332113

  8. Effect of glucocorticoids on the activity, expression and proximal promoter of type II deiodinase in rat brown adipocytes.

    PubMed

    Martinez-deMena, Raquel; Calvo, Rosa-Maria; Garcia, Laura; Obregon, Maria Jesus

    2016-06-15

    Triiodothyronine (T3) is important for thermogenesis in brown adipose tissue (BAT). Type II deiodinase (DIO2) produces T3 required for intracellular needs in BAT. Brown adipocytes in culture require T3 for the adrenergic stimulation of DIO2. Glucocorticoids induce adipocyte differentiation (lipogenesis). We investigated the regulation of DIO2 activity, Dio2 mRNA and Dio2 promoter activity by glucocorticoids in primary cultures of rat brown adipocytes using dexamethasone (DEX) and hydrocortisone (HC). DEX and HC regulated the adrenergic stimulation of DIO2 activity in a dose- and time-dependent manner, inhibiting DIO2 activity at short treatment times and large doses (1-10 μM) and stimulating DIO2 at low HC doses (1-100 nM) and longer times (DEX). Insulin depletion reduced DIO2 activity but the response to glucocorticoids remained unchanged. DEX and HC inhibited basal DIO2 activity. DEX had no effect on DIO2 half-life, whereas HC stabilized DIO2 activity. DEX and HC inhibited the adrenergic stimulation of Dio2 mRNA expression (100-10000 nM, 14-96 h), but stabilized Dio2 mRNA, particularly DEX. DEX increased basal Dio2 mRNA levels, possibly through stabilization of Dio2 mRNA. An 807 bp construct of the murine Dio2 proximal promoter showed maximal reporter activity, with the cAMP response element (CRE) essential for transcriptional activity. DEX caused inhibition in most constructs containing the CRE element whereas HC stimulated reporter activity in the 807 bp construct. Glucocorticoids inhibited the adrenergic stimulation of Dio2 at the transcriptional level in brown adipocytes, although DIO2 activity increased with HC, possibly due to stabilization of Dio2 activity and mRNA. The CRE and cEBP elements of the Dio2 promoter seem involved in the regulation by glucocorticoids. PMID:26994513

  9. Enhanced production of IL-18 in butyrate-treated intestinal epithelium by stimulation of the proximal promoter region.

    PubMed

    Kalina, Uwe; Koyama, Noriko; Hosoda, Tomoko; Nuernberger, Heike; Sato, Kazuto; Hoelzer, Dieter; Herweck, Frank; Manigold, Tobias; Singer, Manfred V; Rossol, Siegbert; Böcker, Ulrich

    2002-09-01

    Expression of IL-18 in intestinal epithelial cells (IEC) has been implicated in Th1 cell-mediated chronic intestinal inflammation and anti-tumor immunity. However, physiological regulatory factors have not been identified. Besides their effects on proliferation and restitution, immunomodulatory functions have been attributed to short chain fatty acids (SCFA). We investigated the effect of SCFA (butyrate, propionate, acetate) on expression of IL-18 in IEC in vitro and in vivo. Expression of IL-18 mRNA and protein in human carcinoma-derived HT-29 and Caco-2 cells was analyzed by reverse transcription-PCR and Western blot. Transcriptional regulation of IL-18 gene expression was determined by transient transfection of wild-type and mutated IL-18 promoter. Further, in vivo expression of IL-18 in the intestine from butyrate-treated and untreated mice was assessed by immunohistochemistry. IL-18 mRNA and the IL-18 protein were expressed in IEC, while IL-18 secretion was not observed. Butyrate and acetate increased intracellular IL-18 content in a time- and dose-dependent fashion. In contrast to proinflammatory stimuli butyrate potently activated the IL-18 promoter, indicating that IL-18 is regulated at the transcriptional level by SCFA. Furthermore, a 108-bp sequence in the proximal region was identified to be essential for IL-18 promoter activation by butyrate. As proof of principle butyrate effects were confirmed in vivo by demonstration of increased IL-18 protein expression in IEC from butyrate-treated mice. In conclusion, SCFA up-regulate IL-18 protein expression in IEC, suggesting a potential regulatory contribution of these luminal constituents to T cell mediated inflammatory and neoplastic intestinal conditions. PMID:12207348

  10. Genome-wide dynamics of Pol II elongation and its interplay with promoter proximal pausing, chromatin, and exons.

    PubMed

    Jonkers, Iris; Kwak, Hojoong; Lis, John T

    2014-01-01

    Production of mRNA depends critically on the rate of RNA polymerase II (Pol II) elongation. To dissect Pol II dynamics in mouse ES cells, we inhibited Pol II transcription at either initiation or promoter-proximal pause escape with Triptolide or Flavopiridol, and tracked Pol II kinetically using GRO-seq. Both inhibitors block transcription of more than 95% of genes, showing that pause escape, like initiation, is a ubiquitous and crucial step within the transcription cycle. Moreover, paused Pol II is relatively stable, as evidenced from half-life measurements at ∼3200 genes. Finally, tracking the progression of Pol II after drug treatment establishes Pol II elongation rates at over 1000 genes. Notably, Pol II accelerates dramatically while transcribing through genes, but slows at exons. Furthermore, intergenic variance in elongation rates is substantial, and is influenced by a positive effect of H3K79me2 and negative effects of exon density and CG content within genes.DOI: http://dx.doi.org/10.7554/eLife.02407.001. PMID:24843027

  11. The proximal promoter of a novel interleukin-8-encoding gene in rainbow trout (Oncorhynchus mykiss) is strongly induced by CEBPA, but not NF-κB p65.

    PubMed

    Rebl, Alexander; Rebl, Henrike; Korytář, Tomáš; Goldammer, Tom; Seyfert, Hans-Martin

    2014-10-01

    Interleukin-8 (IL8) is an immediate-early chemokine that has been well characterized in several fish species. Ten IL8 gene variants have already been described in rainbow trout, but none of their promoters has structurally been defined or functionally characterized in teleost fish. To uncover key factors regulating IL8 expression, we intended to functionally characterize an IL8 promoter from rainbow trout. Incidentally, we isolated a novel IL8 gene variant (IL8-G). It is structurally highly similar to the other trout IL8 gene variants and its mRNA concentration increased significantly in secondary lymphoid tissues after infecting healthy fish with Aeromonas salmonicida. The proximal promoter sequence of the IL8-G-encoding gene features in close proximity two consensus elements for CEBP attachment. The proximal site overlaps with a NF-κB-binding site. Cotransfection of an IL8-G promoter-driven reporter gene together with vectors expressing various mammalian CEBP or NF-κB factors revealed in human HEK-293 cells that CEBPA and NF-κB p50, but not NF-κB p65 activate this promoter. The stimulatory effect of NF-κB p50 is likely conveyed by synergizing with CEBPA. Deletion or mutation of either the distal or the proximal CEBP-binding site, respectively, caused a significant decrease in IL8-G promoter activation. We confirmed the significance of the CEBPA factor for IL8-G expression by comparing the stimulatory capacity of the trout CEBPA and -B factors, thereby reducing the evolutionary distance in the inter-species expression assays. Similar promoter induction potential and intracellular localization of the mammalian and teleostean CEBPA and -B factors suggests their functional conservation throughout evolution. PMID:24721762

  12. Kr-pok increases FASN expression by modulating the DNA binding of SREBP-1c and Sp1 at the proximal promoter[S

    PubMed Central

    Jeon, Bu-Nam; Kim, Yeon-Sook; Choi, Won-Il; Koh, Dong-In; Kim, Min-Kyeong; Yoon, Jae-Hyeon; Kim, Min-Young; Hur, Benjamin; Paik, Philip Dong-Hyun; Hur, Man-Wook

    2012-01-01

    Kr-pok (kidney cancer-related POZ domain and Krüppel-like protein) is a new proto-oncogenic POZ-domain transcription factor. Fatty acid synthase gene (FASN) encodes one of the key enzymes in fatty acids synthesis and is the only enzyme that synthesizes fatty acids in cancer cells. Sp1 and SREBP-1c are the two major transcription activators of FASN. We investigated whether Kr-pok modulates transcription of the FASN. FASN expression is significantly decreased in Kr-pok knockout murine embryonic fibroblasts. Coimmunoprecipitation, GST fusion protein pull-down, and immunocytochemistry assays show that the zinc-finger domain of Kr-pok interacts directly with the bZIP DNA binding domain of SREBP-1. Electrophoretic mobility shift assay, oligonucleotide pull-down, and chromatin immunoprecipitation assays showed that Kr-pok changes the transcription factor binding dynamics of Sp1 and SREBP-1c to the SRE/E-box elements of the proximal promoter. We found that Kr-pok expression increased during 3T3-L1 preadipocyte differentiation and that FASN expression is decreased by the knockdown of Kr-pok. Kr-pok facilitates the SREBP-1c-mediated preadipocyte differentiation and/or fatty acid synthesis. Kr-pok may act as an important regulator of fatty acid synthesis and may induce rapid cancer cell proliferation by increasing palmitate synthesis. PMID:22331133

  13. Identification of a non-canonical E-box motif as a regulatory element in the proximal promoter region of the apolipoprotein E gene.

    PubMed Central

    Salero, Enrique; Giménez, Cecilio; Zafra, Francisco

    2003-01-01

    We have used the yeast one-hybrid system to identify transcription factors with binding capability to specific sequences in proximal regions of the apolipoprotein E gene ( APOE ) promoter. The sequence between -113 and -80 nt, which contains regulatory elements in various cell types, was used as a bait to screen a human brain cDNA library. Four cDNA clones that encoded portions of the human upstream-stimulatory-factor (USF) transcription factor were isolated. Electrophoretic-mobility-shift assays ('EMSAs') using nuclear extracts from various human cell lines as well as from rat brain and liver revealed the formation of two DNA-protein complexes within the sequence CACCTCGTGAC (region -101/-91 of the APOE promoter) that show similarity to the E-box element. The retarded complexes contained USF1, as deduced from competition and supershift assays. Functional experiments using different APOE promoter-luciferase reporter constructs transiently transfected into U87, HepG2 or HeLa cell lines showed that mutations that precluded the formation of complexes decreased the basal activity of the promoter by about 50%. Overexpression of USF1 in U87 glioblastoma cells led to an increased activity of the promoter that was partially mediated by the atypical E-box. The stimulatory effect of USF1 was cell-type specific, as it was not observed in hepatoma HepG2 cells. Similarly, overexpression of a USF1 dominant-negative mutant decreased the basal activity of the promoter in glioblastoma, but not in hepatoma, cells. These data indicated that USF, and probably other related transcription factors, might be involved in the basal transcriptional machinery of APOE by binding to a non-canonical E-box motif within the proximal promoter. PMID:12444925

  14. Transcription activities of human papillomavirus type 11 E6 promoter-proximal elements in raft and submerged cultures of foreskin keratinocytes.

    PubMed Central

    Zhao, W; Chow, L T; Broker, T R

    1997-01-01

    Human papillomaviruses (HPVs) replicate only in differentiated squamous epithelia in warts and in epithelial raft cultures grown at the medium-air interface. Virus-encoded and host transcription factors are thought to be responsible for repressing the viral enhancer and promoter located within the upstream regulatory region (URR) in the undifferentiated basal and parabasal cells while up-regulating their activities in the differentiated spinous cells. Using recombinant retroviruses, we acutely transduced neonatal foreskin keratinocytes (PHKs) with a lacZ reporter gene driven by the wild-type URR of the low-risk HPV type 11 or by a URR with individual mutations in seven promoter-proximal elements, some of which have not been characterized previously. Beta-galactosidase activities were detected in the submerged, proliferating PHKs and also in the differentiated spinous cells, but not in the steady-state proliferating basal cells, of stratified raft cultures. In particular, mutation of an Oct1, an Sp1, or a previously unknown promoter-proximal AP1 site severely reduced the reporter activity, whereas mutation of either of two NF1 sites flanking the Oct1 site had no effect. These results demonstrate changes in cellular transcription factor profiles under different culture conditions and begin to characterize the naturally differentiation-dependent activation of the URR. They provide one molecular explanation for the patterns of HPV expression in warts and help validate epithelial raft cultures as an important experimental system for genetic dissection of HPV regulatory elements. PMID:9343243

  15. Dynamics of Cytosine Methylation in the Proximal Promoters of CYP3A4 and CYP3A7 in Pediatric and Prenatal Livers.

    PubMed

    Vyhlidal, Carrie A; Bi, Chengpeng; Ye, Shui Qing; Leeder, J Steven

    2016-07-01

    Members of the human CYP3A family of metabolizing enzymes exhibit developmental changes in expression whereby CYP3A7 is expressed in fetal tissues, followed by a transition to expression of CYP3A4 in the first months of life. Despite knowledge about the general pattern of CYP3A activity in human development, the mechanisms that regulate developmental expression remain poorly understood. Epigenetic changes, including cytosine methylation, have been suggested to play a role in the regulation of CYP3A expression. The objective of this study was to investigate changes in cytosine methylation of the CYP3A4 and CYP3A7 genes in human pediatric and prenatal livers. The methylation status of cytosine-phospho-guanine dinucleotides was determined in 16 pediatric liver samples using methyl-seq and confirmed by bisulfite sequencing of 48 pediatric and 34 prenatal liver samples. Samples were separated by age into five groups (prenatal, < 1 year of age, 1.8-6 years, 7-11 years, and 12-17 years). Methyl-seq anaylsis revealed that cytosines in the proximal promoter of CYP3A7 are hypomethylated in neonates compared with adolescents (P < 0.001). In contrast, a cytosine 383 base pair upstream of CYP3A4 is hypermethylated in liver samples from neonates compared with adolescents (P = 0.00001). Developmental changes in methylation of cytosines in the proximal promoters of CYP3A4 and CYP3A7 in pediatric livers were confirmed by bisulfite sequencing. In addition, the methylation status of cytosine in the CYP3A4 and CYP3A7 proximal promoters correlated with changes in developmental expression of mRNA for the two enzymes. PMID:26772622

  16. Upstream stimulatory factors, USF1 and USF2, bind to the human haem oxygenase-1 proximal promoter in vivo and regulate its transcription

    PubMed Central

    2004-01-01

    The human HO-1 (haem oxygenase-1) gene encodes a microsomal enzyme responsible for the breakdown of haem, and is also cytoprotective in response to various cellular insults. HO-1 transcription is induced by a vast array of compounds including, but certainly not limited to, haem and heavy metals such as cadmium. In the present study, we show that upstream stimulatory factors, USF1 and USF2, ubiquitous proteins belonging to the basic helix–loop–helix-leucine zipper family of transcription factors, constitutively bind to the class B E-box located in the proximal promoter of the human HO-1 gene and are responsible for the enhancement of HO-1 gene transcription in human renal proximal tubular epithelial cells. Dimethylsulphate in vivo footprinting studies have identified three protected guanine residues in the E-box of the HO-1 proximal promoter. One of these guanine contact points is essential for USF binding, and when mutated mimics a deletion mutation of the entire E-box palindrome sequence encompassing all three guanine contact points. Binding of USF1 and USF2 to the HO-1 E-box was confirmed by chromatin immunoprecipitation and gel-shift assays. Furthermore, we show that overexpression of USF1 or USF2 enhances the basal expression of HO-1 and that expression of a USF dominant negative form reduces its expression. These results demonstrate for the first time that USF proteins bind to the human HO-1 promoter in vivo and are required for high-level expression of HO-1 by haem and cadmium in human renal epithelial cells. PMID:15242350

  17. Uric Acid Promotes Apoptosis in Human Proximal Tubule Cells by Oxidative Stress and the Activation of NADPH Oxidase NOX 4

    PubMed Central

    Verzola, Daniela; Ratto, Elena; Villaggio, Barbara; Parodi, Emanuele Luigi; Pontremoli, Roberto; Garibotto, Giacomo; Viazzi, Francesca

    2014-01-01

    Mild hyperuricemia has been linked to the development and progression of tubulointerstitial renal damage. However the mechanisms by which uric acid may cause these effects are poorly explored. We investigated the effect of uric acid on apoptosis and the underlying mechanisms in a human proximal tubule cell line (HK-2). Increased uric acid concentration decreased tubule cell viability and increased apoptotic cells in a dose dependent manner (up to a 7-fold increase, p<0.0001). Uric acid up-regulated Bax (+60% with respect to Ctrl; p<0.05) and down regulated X-linked inhibitor of apoptosis protein. Apoptosis was blunted by Caspase-9 but not Caspase-8 inhibition. Uric acid induced changes in the mitochondrial membrane, elevations in reactive oxygen species and a pronounced up-regulation of NOX 4 mRNA and protein (p<0.05). In addition, both reactive oxygen species production and apoptosis was prevented by the NADPH oxidase inhibitor DPI as well as by Nox 4 knockdown. URAT 1 transport inhibition by probenecid and losartan and its knock down by specific siRNA, blunted apoptosis, suggesting a URAT 1 dependent cell death. In summary, our data show that uric acid increases the permissiveness of proximal tubule kidney cells to apoptosis by triggering a pathway involving NADPH oxidase signalling and URAT 1 transport. These results might explain the chronic tubulointerstitial damage observed in hyperuricaemic states and suggest that uric acid transport in tubular cells is necessary for urate-induced effects. PMID:25514209

  18. Characterization of the Mouse and Human Monoacylglycerol O-Acyltransferase 1 (Mogat1) Promoter in Human Kidney Proximal Tubule and Rat Liver Cells.

    PubMed

    Sankella, Shireesha; Garg, Abhimanyu; Agarwal, Anil K

    2016-01-01

    Monoacylglycerol acyltransferase 1 (Mogat1) catalyzes the conversion of monoacylglycerols (MAG) to diacylglycerols (DAG), the precursor of several physiologically important lipids such as phosphatidylcholine, phosphatidylethanolamine and triacylglycerol (TAG). Expression of Mogat1 is tissue restricted and it is highly expressed in the kidney, stomach and adipose tissue but minimally in the normal adult liver. To understand the transcriptional regulation of Mogat1, we characterized the mouse and human Mogat1 promoters in human kidney proximal tubule-2 (HK-2) cells. In-silico analysis revealed several peroxisome proliferator response element (PPRE) binding sites in the promoters of both human and mouse Mogat1. These sites responded to all three peroxisome proliferator activated receptor (PPAR) isoforms such that their respective agonist or antagonist activated or inhibited the expression of Mogat1. PPRE site mutagenesis revealed that sites located at -592 and -2518 are very effective in decreasing luciferase reporter gene activity. Chromatin immunoprecipitation (ChIP) assay using PPARα antibody further confirmed the occupancy of these sites by PPARα. While these assays revealed the core promoter elements necessary for Mogat1 expression, there are additional elements required to regulate its tissue specific expression. Chromosome conformation capture (3C) assay revealed additional cis-elements located ~10-15 kb upstream which interact with the core promoter. These chromosomal regions are responsive to both PPARα agonist and antagonist. PMID:27611931

  19. Chromatin immunoprecipitation assays revealed CREB and serine 133 phospho-CREB binding to the CART gene proximal promoter

    PubMed Central

    Rogge, George A; Shen, Li-Ling; Kuhar, Michael J.

    2010-01-01

    Both over expression of cyclic AMP response element binding protein (CREB) in the nucleus accumbens (NAc), and intra-accumbal injection of cocaine- and amphetamine-regulated transcript (CART) peptides, have been shown to decrease cocaine reward. Also, over expression of CREB in the rat NAc increased CART mRNA and peptide levels, but it is not known if this was due to a direct action of P-CREB on the CART gene promoter. The goal of this study was to test if CREB and P-CREB bound directly to the CRE site in the CART promoter, using chromatin immunoprecipitation (ChIP) assays. ChIP assay with anti-CREB antibodies showed an enrichment of the CART promoter fragment containing the CRE region over IgG precipitated material, a non-specific control. Forskolin, which was known to increase CART mRNA levels in GH3 cells, was utilized to show that the drug increased levels of P-CREB protein and P-CREB binding to the CART promoter CRE-containing region. A region of the c-Fos promoter containing a CRE cis-regulatory element was previously shown to bind P-CREB, and it was used here as a positive control. These data suggest that the effects of CREB over expression on blunting cocaine reward could be, at least in part, attributed to the increased expression of the CART gene by direct interaction of P-CREB with the CART promoter CRE site, rather than by some indirect action. PMID:20451507

  20. Adenosine, type 1 receptors: role in proximal tubule Na+ reabsorption.

    PubMed

    Welch, W J

    2015-01-01

    Adenosine type 1 receptor (A1 -AR) antagonists induce diuresis and natriuresis in experimental animals and humans. Much of this effect is due to inhibition of A1 -ARs in the proximal tubule, which is responsible for 60-70% of the reabsorption of filtered Na(+) and fluid. Intratubular application of receptor antagonists indicates that A1 -AR mediates a portion of Na(+) uptake in PT and PT cells, via multiple transport systems, including Na(+) /H(+) exchanger-3 (NHE3), Na(+) /PO4(-) co-transporter and Na(+) -dependent glucose transporter, SGLT. Renal microperfusion and recollection studies have shown that fluid reabsorption is reduced by A1 -AR antagonists and is lower in A1 -AR KO mice, compared to WT mice. Absolute proximal reabsorption (APR) measured by free-flow micropuncture is equivocal, with studies that show either lower APR or similar APR in A1 -AR KO mice, compared to WT mice. Inhibition of A1 -ARs lowers elevated blood pressure in models of salt-sensitive hypertension, partially due to their effects in the proximal tubule. PMID:25345761

  1. Proximal Nephron

    PubMed Central

    Zhuo, Jia L.; Li, Xiao C.

    2013-01-01

    The kidney plays a fundamental role in maintaining body salt and fluid balance and blood pressure homeostasis through the actions of its proximal and distal tubular segments of nephrons. However, proximal tubules are well recognized to exert a more prominent role than distal counterparts. Proximal tubules are responsible for reabsorbing approximately 65% of filtered load and most, if not all, of filtered amino acids, glucose, solutes, and low molecular weight proteins. Proximal tubules also play a key role in regulating acid-base balance by reabsorbing approximately 80% of filtered bicarbonate. The purpose of this review article is to provide a comprehensive overview of new insights and perspectives into current understanding of proximal tubules of nephrons, with an emphasis on the ultrastructure, molecular biology, cellular and integrative physiology, and the underlying signaling transduction mechanisms. The review is divided into three closely related sections. The first section focuses on the classification of nephrons and recent perspectives on the potential role of nephron numbers in human health and diseases. The second section reviews recent research on the structural and biochemical basis of proximal tubular function. The final section provides a comprehensive overview of new insights and perspectives in the physiological regulation of proximal tubular transport by vasoactive hormones. In the latter section, attention is particularly paid to new insights and perspectives learnt from recent cloning of transporters, development of transgenic animals with knockout or knockin of a particular gene of interest, and mapping of signaling pathways using microarrays and/or physiological proteomic approaches. PMID:23897681

  2. MIKC* MADS-Protein Complexes Bind Motifs Enriched in the Proximal Region of Late Pollen-Specific Arabidopsis Promoters[W

    PubMed Central

    Verelst, Wim; Saedler, Heinz; Münster, Thomas

    2007-01-01

    The genome of Arabidopsis (Arabidopsis thaliana) encodes over 100 MADS-domain transcription factors, categorized into five phylogenetic subgroups. Most research efforts have focused on just one of these subgroups (MIKCc), whereas the other four remain largely unexplored. Here, we report on five members of the so-called Mδ or Arabidopsis MIKC* (AtMIKC*) subgroup, which are predominantly expressed during the late stages of pollen development. Very few MADS-box genes function in mature pollen, and from this perspective, the AtMIKC* genes are therefore highly exceptional. We found that the AtMIKC* proteins are able to form multiple heterodimeric complexes in planta, and that these protein complexes exhibit a for the MADS-family unusual and high DNA binding specificity in vitro. Compared to their occurrence in promoters genome wide, AtMIKC* binding sites are strongly overrepresented in the proximal region of late pollen-specific promoters. By combining our experimental data with in silico genomics and pollen transcriptomics approaches, we identified a considerable number of putative direct target genes of the AtMIKC* transcription factor complexes in pollen, many of which have known or proposed functions in pollen tube growth. The expression of several of these predicted targets is altered in mutant pollen in which all AtMIKC* complexes are affected, and in vitro germination of this mutant pollen is severely impaired. Our data therefore suggest that the AtMIKC* protein complexes play an essential role in transcriptional regulation during late pollen development. PMID:17071640

  3. Modifications of protein-DNA interactions in the proximal promoter of a cell-growth-regulated histone gene during onset and progression of osteoblast differentiation.

    PubMed Central

    Owen, T A; Holthuis, J; Markose, E; van Wijnen, A J; Wolfe, S A; Grimes, S R; Lian, J B; Stein, G S

    1990-01-01

    A temporal sequence of interrelated cellular, biochemical, and molecular events which occurs during the progressive expression of the differentiated osteoblast phenotype in primary cultures of fetal rat calvarial cells results in the development of a bone-tissue-like organization. This ordered developmental sequence encompasses three periods: proliferation, matrix maturation, and mineralization. Initially, the cells actively proliferate and synthesize type I collagen. This is followed by a period of matrix organization and maturation and then by a period of extracellular matrix mineralization. At the completion of proliferation, when expression of osteoblast phenotype markers such as alkaline phosphatase is observed, the cell-cycle-related histone genes are down-regulated transcriptionally, suggesting that a key signaling mechanism at this transition point involves modifications of protein-DNA interactions in the regulatory elements of these growth-regulated genes. Our results demonstrate that there is a selective loss of interaction of the promoter binding factor HiNF-D with the site II region of an H4 histone gene proximal promoter that regulates the specificity and level of transcription only when the down-regulation of proliferation is accompanied by modifications in the extracellular matrix that contribute to progression of osteoblast differentiation. Thus, this specific loss of protein-DNA interaction serves as a marker for a key transition point in the osteoblast developmental sequence, where the down-regulation of proliferation is functionally coupled to the appearance of osteoblast phenotypic properties associated with the organization and maturation of an extracellular matrix that becomes competent to mineralize. Images PMID:2367528

  4. Liposomal vaccines incorporating molecular adjuvants and intrastructural T-cell help promote the immunogenicity of HIV membrane-proximal external region peptides

    PubMed Central

    Hanson, Melissa C.; Abraham, Wuhbet; Crespo, Monica P.; Chen, Stephanie H.; Liu, Haipeng; Szeto, Greg Lee; Kim, Mikyung; Reinherz, Ellis L.; Irvine, Darrell J.

    2015-01-01

    An HIV vaccine capable of inducing high and durable levels of broadly neutralizing antibodies has thus far proven elusive. A promising antigen is the membrane-proximal external region (MPER) from gp41, a segment of the viral envelope recognized by a number of broadly neutralizing antibodies. Though an attractive vaccine target due to the linear nature of the epitope and its highly conserved sequence, MPER peptides are poorly immunogenic and may require display on membranes to achieve a physiological conformation matching the native virus. Here we systematically explored how the structure and composition of liposomes displaying MPER peptides impacts the strength and durability of humoral responses to this antigen as well as helper T-cell responses in mice. Administration of MPER peptides anchored to the surface of liposomes induced MPER-specific antibodies whereas MPER administered in oil-based emulsion adjuvants or alum did not, even when combined with Toll like receptor agonists. High-titer IgG responses to liposomal MPER required the inclusion of molecular adjuvants such as monophosphoryl lipid A. Anti-MPER humoral responses were further enhanced by incorporating high-Tm lipids in the vesicle bilayer and optimizing the MPER density to a mean distance of ~10–15 nm between peptides on the liposomes' surfaces. Encapsulation of helper epitopes within the vesicles allowed efficient “intrastructural” T-cell help, which promoted IgG responses to MPER while minimizing competing B-cell responses against the helper sequence. These results define several key properties of liposome formulations that promote durable, high-titer antibody responses against MPER peptides, which will be a prerequisite for a successful MPER-targeting vaccine. PMID:25559188

  5. Transcriptional regulation of the PXR gene: identification and characterization of a functional peroxisome proliferator-activated receptor alpha binding site within the proximal promoter of PXR.

    PubMed

    Aouabdi, Sihem; Gibson, Gordon; Plant, Nick

    2006-01-01

    The pregnane X receptor (PXR, NR1I2) is widely regarded as a central factor in the body's response to changes in the fluxome, the overall metabolite profile in the body. PXR expression is regulated by a number of chemicals at the transcriptional level; the majority of these chemicals are ligands for PXR and substrates for PXR target genes. However, transcriptional activators of PXR, such as clofibrate, do not seem to be PXR ligands or substrates for its target genes. Understanding the molecular mechanisms underlying both these expected and, more importantly, unexpected transcriptional activations is central to fully understanding the roles of PXR in the human body. We have carried out an in silico analysis of the human PXR proximal promoter, identifying putative protein/DNA interaction sites within the 2 kilobases (kb) 5' to the putative transcription start site. These sites included several for liver-enriched transcription factors, such as the hepatic nuclear factors and CAAT-enhancer binding protein alpha, and chicken ovalbumin upstream promoter transcription factor, commensurate with the high expression of PXR in liver. Furthermore, we identified putative binding sites for a number of ligand-activated transcription factors, suggesting that these factors may regulate PXR gene expression. Further analysis of this regulatory region has shown that transcriptional activation of PXR by peroxisome proliferator-activated receptor alpha (PPARalpha) is via a binding site located approximately 1.3 kb upstream of the putative transcription start site, with ablation of this site preventing PPARalpha-mediated activation of PXR gene expression. We present a model of how regulation of PXR gene expression by ligand-activated transcription factors may play a central role in the body's response to xenobiotic exposure. PMID:16243957

  6. The catecholamine biosynthetic enzyme dopamine β-hydroxylase (DBH): first genome-wide search positions trait-determining variants acting additively in the proximal promoter

    PubMed Central

    Mustapic, Maja; Maihofer, Adam X.; Mahata, Manjula; Chen, Yuqing; Baker, Dewleen G.; O'Connor, Daniel T.; Nievergelt, Caroline M.

    2014-01-01

    Dopamine beta-hydroxylase (DBH) is the biosynthetic enzyme catalyzing formation of norepinephrine. Changes in DBH expression or activity have been implicated in the pathogenesis of cardiovascular and neuropsychiatric disorders. Genetic determination of DBH enzymatic activity and its secretion are only incompletely understood. We began with a genome-wide association search for loci contributing to DBH activity in human plasma. Initially, in a population sample of European ancestry, we identified the proximal DBH promoter as a region harboring three common trait-determining variants (top hit rs1611115, P = 7.2 × 10−51). We confirmed their effects on transcription and showed that the three variants each acted additively on gene expression. Results were replicated in a population sample of Native American descent (top hit rs1611115, P = 4.1 × 10−15). Jointly, DBH variants accounted for 57% of DBH trait variation. We further identified a genome-wide significant SNP at the LOC338797 locus on chromosome 12 as trans-quantitative trait locus (QTL) (rs4255618, P = 4.62 × 10−8). Conditional analyses on DBH identified a third genomic region contributing to DBH variation: a likely cis-QTL adjacent to DBH in SARDH (rs7040170, P = 1.31 × 10−14) on chromosome 9q. We conclude that three common SNPs in the DBH promoter act additively to control phenotypic variation in DBH levels, and that two additional novel loci (SARDH and LOC338797) may also contribute to the expression of this catecholamine biosynthetic trait. Identification of DBH variants with strong effects makes it possible to take advantage of Mendelian randomization approaches to test causal effects of this intermediate trait on disease. PMID:24986918

  7. Short-term nonpressor angiotensin II infusion stimulates sodium transporters in proximal tubule and distal nephron

    PubMed Central

    Nguyen, Mien T X; Han, Jiyang; Ralph, Donna L; Veiras, Luciana C; McDonough, Alicia A

    2015-01-01

    In Sprague Dawley rats, 2-week angiotensin II (AngII) infusion increases Na+ transporter abundance and activation from cortical thick ascending loop of Henle (TALH) to medullary collecting duct (CD) and raises blood pressure associated with a pressure natriuresis, accompanied by depressed Na+ transporter abundance and activation from proximal tubule (PT) through medullary TALH. This study tests the hypothesis that early during AngII infusion, before blood pressure raises, Na+ transporters’ abundance and activation increase all along the nephron. Male Sprague Dawley rats were infused via osmotic minipumps with a subpressor dose of AngII (200 ng/kg/min) or vehicle for 3 days. Overnight urine was collected in metabolic cages and sodium transporters’ abundance and phosphorylation were determined by immunoblotting homogenates of renal cortex and medulla. There were no significant differences in body weight gain, overnight urine volume, urinary Na+ and K+ excretion, or rate of excretion of a saline challenge between AngII and vehicle infused rats. The 3-day nonpressor AngII infusion significantly increased the abundance of PT Na+/H+ exchanger 3 (NHE3), cortical TALH Na-K-2Cl cotransporter 2 (NKCC2), distal convoluted tubule (DCT) Na-Cl cotransporter (NCC), and cortical CD ENaC subunits. Additionally, phosphorylation of cortical NKCC2, NCC, and STE20/SPS1-related proline–alanine-rich kinase (SPAK) were increased; medullary NKCC2 and SPAK were not altered. In conclusion, 3-day AngII infusion provokes PT NHE3 accumulation as well as NKCC2, NCC, and SPAK accumulation and activation in a prehypertensive phase before evidence for intrarenal angiotensinogen accumulation. PMID:26347505

  8. Mechanisms of proximal tubule sodium transport regulation that link extracellular fluid volume and blood pressure.

    PubMed

    McDonough, Alicia A

    2010-04-01

    One-hundred years ago, Starling articulated the interdependence of renal control of circulating blood volume and effective cardiac performance. During the past 25 years, the molecular mechanisms responsible for the interdependence of blood pressure (BP), extracellular fluid volume (ECFV), the renin-angiotensin system (RAS), and sympathetic nervous system (SNS) have begun to be revealed. These variables all converge on regulation of renal proximal tubule (PT) sodium transport. The PT reabsorbs two-thirds of the filtered Na(+) and volume at baseline. This fraction is decreased when BP or perfusion pressure is increased, during a high-salt diet (elevated ECFV), and during inhibition of the production of ANG II; conversely, this fraction is increased by ANG II, SNS activation, and a low-salt diet. These variables all regulate the distribution of the Na(+)/H(+) exchanger isoform 3 (NHE3) and the Na(+)-phosphate cotransporter (NaPi2), along the apical microvilli of the PT. Natriuretic stimuli provoke the dynamic redistribution of these transporters along with associated regulators, molecular motors, and cytoskeleton-associated proteins to the base of the microvilli. The lipid raft-associated NHE3 remains at the base, and the nonraft-associated NaPi2 is endocytosed, culminating in decreased Na(+) transport and increased PT flow rate. Antinatriuretic stimuli return the same transporters and regulators to the body of the microvilli associated with an increase in transport activity and decrease in PT flow rate. In summary, ECFV and BP homeostasis are, at least in part, maintained by continuous and acute redistribution of transporter complexes up and down the PT microvilli, which affect regulation of PT sodium reabsorption in response to fluctuations in ECFV, BP, SNS, and RAS. PMID:20106993

  9. Reduced Epithelial Na+/H+ Exchange Drives Gut Microbial Dysbiosis and Promotes Inflammatory Response in T Cell-Mediated Murine Colitis

    PubMed Central

    Midura-Kiela, Monica T.; Ramalingam, Rajalakshmy; Larmonier, Claire B.; Chase, John H.; Caporaso, J. Gregory; Besselsen, David G.; Ghishan, Fayez K.; Kiela, Pawel R.

    2016-01-01

    Inflammatory bowel diseases (IBD) are associated with functional inhibition of epithelial Na+/H+ exchange. In mice, a selective disruption of NHE3 (Slc9a3), a major apical Na+/H+ exchanger, also promotes IBD-like symptoms and gut microbial dysbiosis. We hypothesized that disruption of Na+/H+ exchange is necessary for the development of dysbiosis, which promotes an exacerbated mucosal inflammatory response. Therefore, we performed a temporal analysis of gut microbiota composition, and mucosal immune response to adoptive T cell transfer was evaluated in Rag2-/- and NHE3-/-/Rag2-/- (DKO) mice with and without broad-spectrum antibiotics. Microbiome (16S profiling), colonic histology, T cell and neutrophil infiltration, mucosal inflammatory tone, and epithelial permeability were analyzed. In adoptive T cell transfer colitis model, Slc9a3 status was the most significant determinant of gut microbial community. In DKO mice, NHE3-deficiency and dysbiosis were associated with dramatically accelerated and exacerbated disease, with rapid body weight loss, increased mucosal T cell and neutrophil influx, increased mucosal cytokine expression, increased permeability, and expansion of CD25-FoxP3+ Tregs; this enhanced susceptibility was alleviated by oral broad-spectrum antibiotics. Based on these results and our previous work, we postulate that epithelial electrolyte homeostasis is an important modulator in the progression of colitis, acting through remodeling of the gut microbial community. PMID:27050757

  10. Reduced Epithelial Na+/H+ Exchange Drives Gut Microbial Dysbiosis and Promotes Inflammatory Response in T Cell-Mediated Murine Colitis.

    PubMed

    Laubitz, Daniel; Harrison, Christy A; Midura-Kiela, Monica T; Ramalingam, Rajalakshmy; Larmonier, Claire B; Chase, John H; Caporaso, J Gregory; Besselsen, David G; Ghishan, Fayez K; Kiela, Pawel R

    2016-01-01

    Inflammatory bowel diseases (IBD) are associated with functional inhibition of epithelial Na+/H+ exchange. In mice, a selective disruption of NHE3 (Slc9a3), a major apical Na+/H+ exchanger, also promotes IBD-like symptoms and gut microbial dysbiosis. We hypothesized that disruption of Na+/H+ exchange is necessary for the development of dysbiosis, which promotes an exacerbated mucosal inflammatory response. Therefore, we performed a temporal analysis of gut microbiota composition, and mucosal immune response to adoptive T cell transfer was evaluated in Rag2-/- and NHE3-/-/Rag2-/- (DKO) mice with and without broad-spectrum antibiotics. Microbiome (16S profiling), colonic histology, T cell and neutrophil infiltration, mucosal inflammatory tone, and epithelial permeability were analyzed. In adoptive T cell transfer colitis model, Slc9a3 status was the most significant determinant of gut microbial community. In DKO mice, NHE3-deficiency and dysbiosis were associated with dramatically accelerated and exacerbated disease, with rapid body weight loss, increased mucosal T cell and neutrophil influx, increased mucosal cytokine expression, increased permeability, and expansion of CD25-FoxP3+ Tregs; this enhanced susceptibility was alleviated by oral broad-spectrum antibiotics. Based on these results and our previous work, we postulate that epithelial electrolyte homeostasis is an important modulator in the progression of colitis, acting through remodeling of the gut microbial community. PMID:27050757

  11. Proximity fuze

    DOEpatents

    Harrison, Thomas R.

    1989-08-22

    A proximity fuze system includes an optical ranging apparatus, a detonation circuit controlled by the optical ranging apparatus, and an explosive charge detonated by the detonation cirtcuit. The optical ranging apparatus includes a pulsed laser light source for generating target ranging light pulses and optical reference light pulses. A single lens directs ranging pulses to a target and collects reflected light from the target. An optical fiber bundle is used for delaying the optical reference pulses to correspond to a predetermined distance from the target. The optical ranging apparatus includes circuitry for providing a first signal depending upon the light pulses reflected from the target, a second signal depending upon the light pulses from the optical delay fiber bundle, and an output signal when the first and second signals coincide with each other. The output signal occurs when the distance from the target is equal to the predetermined distance form the target. Additional circuitry distinguishes pulses reflected from the target from background solar radiation.

  12. Proximity fuze

    DOEpatents

    Harrison, T.R.

    1987-07-10

    A proximity fuze system includes an optical ranging apparatus, a detonation circuit controlled by the optical ranging apparatus, and an explosive charge detonated by the detonation circuit. The optical ranging apparatus includes a pulsed laser light source for generating target ranging light pulses and optical reference light pulses. A single lens directs ranging pulses to a target and collects reflected light from the target. An optical fiber bundle is used for delaying the optical reference pulses to correspond to a predetermined distance from the target. The optical ranging apparatus includes circuitry for providing a first signal depending upon the light pulses reflected from the target, a second signal depending upon the light pulses from the optical delay fiber bundle, and an output signal when the first and second signals coincide with each other. The output signal occurs when the distance from the target is equal to the predetermined distance from the target. Additional circuitry distinguishes pulses reflected from the target from background solar radiation. 3 figs.

  13. Promotion

    PubMed Central

    Alam, Hasan B.

    2013-01-01

    This article gives an overview of the promotion process in an academic medical center. A description of different promotional tracks, tenure and endowed chairs, and the process of submitting an application is provided. Finally, some practical advice about developing skills and attributes that can help with academic growth and promotion is dispensed. PMID:24436683

  14. Proximal renal tubular acidosis

    MedlinePlus

    Renal tubular acidosis - proximal; Type II RTA; RTA - proximal; Renal tubular acidosis type II ... by alkaline substances, mainly bicarbonate. Proximal renal tubular acidosis (Type II RTA) occurs when bicarbonate is not ...

  15. Proximal Tibial Bone Graft

    MedlinePlus

    ... Complications Potential problems after a PTBG include infection, fracture of the proximal tibia and pain related to the procedure. Frequently Asked Questions If proximal tibial bone graft is taken from my knee, will this prevent me from being able to ...

  16. Negative Elongation Factor Is Required for the Maintenance of Proviral Latency but Does Not Induce Promoter-Proximal Pausing of RNA Polymerase II on the HIV Long Terminal Repeat

    PubMed Central

    Jadlowsky, Julie K.; Wong, Julian Y.; Graham, Amy C.; Dobrowolski, Curtis; Devor, Renee L.; Adams, Mark D.; Fujinaga, Koh

    2014-01-01

    The role of the negative elongation factor (NELF) in maintaining HIV latency was investigated following small hairpin RNA (shRNA) knockdown of the NELF-E subunit, a condition that induced high levels of proviral transcription in latently infected Jurkat T cells. Chromatin immunoprecipitation (ChIP) assays showed that latent proviruses accumulate RNA polymerase II (RNAP II) on the 5′ long terminal repeat (LTR) but not on the 3′ LTR. NELF colocalizes with RNAP II, and its level increases following proviral induction. RNAP II pause sites on the HIV provirus were mapped to high resolution by ChIP with high-throughput sequencing (ChIP-Seq). Like cellular promoters, RNAP II accumulates at around position +30, but HIV also shows additional pausing at +90, which is immediately downstream of a transactivation response (TAR) element and other distal sites on the HIV LTR. Following NELF-E knockdown or tumor necrosis factor alpha (TNF-α) stimulation, promoter-proximal RNAP II levels increase up to 3-fold, and there is a dramatic increase in RNAP II levels within the HIV genome. These data support a kinetic model for proviral transcription based on continuous replacement of paused RNAP II during both latency and productive transcription. In contrast to most cellular genes, HIV is highly activated by the combined effects of NELF-E depletion and activation of initiation by TNF-α, suggesting that opportunities exist to selectively activate latent HIV proviruses. PMID:24636995

  17. Negative elongation factor is required for the maintenance of proviral latency but does not induce promoter-proximal pausing of RNA polymerase II on the HIV long terminal repeat.

    PubMed

    Jadlowsky, Julie K; Wong, Julian Y; Graham, Amy C; Dobrowolski, Curtis; Devor, Renee L; Adams, Mark D; Fujinaga, Koh; Karn, Jonathan

    2014-06-01

    The role of the negative elongation factor (NELF) in maintaining HIV latency was investigated following small hairpin RNA (shRNA) knockdown of the NELF-E subunit, a condition that induced high levels of proviral transcription in latently infected Jurkat T cells. Chromatin immunoprecipitation (ChIP) assays showed that latent proviruses accumulate RNA polymerase II (RNAP II) on the 5' long terminal repeat (LTR) but not on the 3' LTR. NELF colocalizes with RNAP II, and its level increases following proviral induction. RNAP II pause sites on the HIV provirus were mapped to high resolution by ChIP with high-throughput sequencing (ChIP-Seq). Like cellular promoters, RNAP II accumulates at around position +30, but HIV also shows additional pausing at +90, which is immediately downstream of a transactivation response (TAR) element and other distal sites on the HIV LTR. Following NELF-E knockdown or tumor necrosis factor alpha (TNF-α) stimulation, promoter-proximal RNAP II levels increase up to 3-fold, and there is a dramatic increase in RNAP II levels within the HIV genome. These data support a kinetic model for proviral transcription based on continuous replacement of paused RNAP II during both latency and productive transcription. In contrast to most cellular genes, HIV is highly activated by the combined effects of NELF-E depletion and activation of initiation by TNF-α, suggesting that opportunities exist to selectively activate latent HIV proviruses. PMID:24636995

  18. SUV420H2-Mediated H4K20 Trimethylation Enforces RNA Polymerase II Promoter-Proximal Pausing by Blocking hMOF-Dependent H4K16 Acetylation ▿

    PubMed Central

    Kapoor-Vazirani, Priya; Kagey, Jacob D.; Vertino, Paula M.

    2011-01-01

    Many human genes exhibit evidence of initiated RNA polymerase II (Pol II) at their promoters, despite a lack of significant full-length transcript. Such genes exhibit promoter-proximal “pausing,” wherein initiated Pol II accumulates just downstream of the transcription start site due to a rate-limiting step mediating the transition to elongation. The mechanisms that regulate the escape of Pol II from pausing and the relationship to chromatin structure remain incompletely understood. Recently, we showed that CpG island hypermethylation and epigenetic silencing of TMS1/ASC in human breast cancers are accompanied by a local shift from histone H4 lysine 16 acetylation (H4K16Ac) to H4 lysine 20 trimethylation (H4K20me3). Here, we show that hMOF-mediated H4K16Ac and SUV420H2-mediated H4K20me3 play opposing roles in the regulation of Pol II pausing. We found that H4K16Ac promoted the release of Pol II from pausing through the recruitment of BRD4 and pTEFb. Aberrant methylation of CpG island DNA blocked Pol II recruitment to gene promoters. Whereas the inhibition of DNA methylation allowed for the reassociation and initiation of Pol II at the TMS1 promoter, Pol II remained paused in the presence of H4K20me3. Combined inhibition of H4K20me3 and DNA methylation resulted in the rerecruitment of hMOF and subsequent H4K16Ac, release of Pol II into active elongation, and synergistic reactivation of TMS1 expression. Marking by H4K20me3 was not restricted to TMS1 but also occurred at other genes independently of DNA methylation, where it similarly imposed a block to Pol II promoter escape through a mechanism that involved the local inhibition of H4K16Ac. These data indicate that H4K20me3 invokes gene repression by antagonizing hMOF-mediated H4K16Ac and suggest that overcoming Pol II pausing might be a rate-limiting step in achieving tumor suppressor gene reactivation in cancer therapy. PMID:21321083

  19. Parathyroid hormone inhibition of Na{sup +}/H{sup +} exchanger 3 transcription: Intracellular signaling pathways and transcription factor expression

    SciTech Connect

    Neri, Elida Adalgisa; Bezerra, Camila Nogueira Alves Queiroz-Leite, Gabriella Duarte; Polidoro, Juliano Zequini; Rebouças, Nancy Amaral

    2015-06-12

    The main transport mechanism of reabsorption of sodium bicarbonate and fluid in the renal proximal tubules involves Na{sup +}/H{sup +} exchanger 3 (NHE3), which is acutely and chronically downregulated by parathyroid hormone (PTH). Although PTH is known to exert an inhibitory effect on NHE3 expression and transcription, the molecular mechanisms involved remain unclear. Here, we demonstrated that, in opossum kidney proximal tubule (OKP) cells, PTH-induced inhibition of Nhe3 gene promoter occurs even in the core promoter that controls expression of the reporter gene. We found that inhibition of the protein kinase A (PKA) and Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathways transformed PTH from an inhibitor of promoter activity into an activator of that same activity, as did point mutations in the EGR1, Sp1, and Sp3 binding consensus elements in the promoter. In nuclear extracts of PTH-treated OKP cells, we also observed increased expression of EGR1 mRNA and of some Sp3 isoforms. Electrophoretic mobility shift assay showed a supershift of the −61 to −42-bp probe with an anti-EGR1 antibody in PTH-treated cells, suggesting that EGR1 binding is relevant for the inhibitory activity of PTH. We conclude that PTH-induced inhibition of NHE3 transcription is related to higher EGR1 expression; to EGR1 binding to the proximal and core promoters; and to PKA and JAK/STAT pathway activation. This mechanism might be responsible, at least in part, for lower NHE3 expression and sodium reabsorption in renal proximal tubules in the presence of high PTH levels. - Highlights: • PTH regulation of Nhe3 promoter depends on EGR1 binding. • EGR1, PKA and JAK/STAT are involved in PTH inhibition of the Nhe3 promoter. • PTH alters expression of EGR1 and Sp3. • PTH inhibits the Nhe3 promoter by regulating PKA and JAK/STAT signaling.

  20. Regulation of glomerulotubular balance. III. Implication of cytosolic calcium in flow-dependent proximal tubule transport.

    PubMed

    Du, Zhaopeng; Weinbaum, Sheldon; Weinstein, Alan M; Wang, Tong

    2015-04-15

    In the proximal tubule, axial flow (drag on brush-border microvilli) stimulates Na(+) and HCO3 (-) reabsorption by modulating both Na/H exchanger 3 (NHE3) and H-ATPase activity, a process critical to glomerulotubular balance. We have also demonstrated that blocking the angiotensin II receptor decreases baseline transport, but preserves the flow effect; dopamine leaves baseline fluxes intact, but abrogates the flow effect. In the current work, we provide evidence implicating cytosolic calcium in flow-dependent transport. Mouse proximal tubules were microperfused in vitro at perfusion rates of 5 and 20 nl/min, and reabsorption of fluid (Jv) and HCO3 (-) (JHCO3) were measured. We examined the effect of high luminal Ca(2+) (5 mM), 0 mM Ca(2+), the Ca(2+) chelator BAPTA-AM, the inositol 1,4,5-trisphosphate (IP3) receptor antagonist 2-aminoethoxydiphenyl borate (2-APB), and the Ca-ATPase inhibitor thapsigargin. In control tubules, increasing perfusion rate from 5 to 20 nl/min increased Jv by 62% and JHCO3 by 104%. With respect to Na(+) reabsorption, high luminal Ca(2+) decreased transport at low flow, but preserved the flow-induced increase; low luminal Ca(2+) had little impact; both BAPTA and 2-APB had no effect on baseline flux, but abrogated the flow effect; thapsigargin decreased baseline flow, leaving the flow effect intact. With respect to HCO3 (-) reabsorption, high luminal Ca(2+) decreased transport at low flow and mildly diminished the flow-induced increase; low luminal Ca(2+) had little impact; both BAPTA and 2-APB had no effect on baseline flux, but abrogated the flow effect. These data implicate IP3 receptor-mediated intracellular Ca(2+) signaling as a critical step in transduction of microvillous drag to modulate Na(+) and HCO3 (-) transport. PMID:25651568

  1. Proximal tibiofibular synostosis.

    PubMed

    Wong, K; Weiner, D S

    1978-09-01

    The occurrence of a proximal tibiofibular synostosis is indeed a rare condition with only 2 cases unassociated with other diseases reported to our knowledge to date. Two skeletally immature patients presented with a synostosis of the proximal tibiofibular region associated with shortening of the limb in the affected segments. Although the shortening and the synostosis seem interrelated no explanation of their relationship is evident from these 2 cases. PMID:709951

  2. Parathyroid hormone inhibition of Na(+)/H(+) exchanger 3 transcription: Intracellular signaling pathways and transcription factor expression.

    PubMed

    Neri, Elida Adalgisa; Bezerra, Camila Nogueira Alves; Queiroz-Leite, Gabriella Duarte; Polidoro, Juliano Zequini; Rebouças, Nancy Amaral

    2015-06-12

    The main transport mechanism of reabsorption of sodium bicarbonate and fluid in the renal proximal tubules involves Na(+)/H(+) exchanger 3 (NHE3), which is acutely and chronically downregulated by parathyroid hormone (PTH). Although PTH is known to exert an inhibitory effect on NHE3 expression and transcription, the molecular mechanisms involved remain unclear. Here, we demonstrated that, in opossum kidney proximal tubule (OKP) cells, PTH-induced inhibition of Nhe3 gene promoter occurs even in the core promoter that controls expression of the reporter gene. We found that inhibition of the protein kinase A (PKA) and Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathways transformed PTH from an inhibitor of promoter activity into an activator of that same activity, as did point mutations in the EGR1, Sp1, and Sp3 binding consensus elements in the promoter. In nuclear extracts of PTH-treated OKP cells, we also observed increased expression of EGR1 mRNA and of some Sp3 isoforms. Electrophoretic mobility shift assay showed a supershift of the -61 to -42-bp probe with an anti-EGR1 antibody in PTH-treated cells, suggesting that EGR1 binding is relevant for the inhibitory activity of PTH. We conclude that PTH-induced inhibition of NHE3 transcription is related to higher EGR1 expression; to EGR1 binding to the proximal and core promoters; and to PKA and JAK/STAT pathway activation. This mechanism might be responsible, at least in part, for lower NHE3 expression and sodium reabsorption in renal proximal tubules in the presence of high PTH levels. PMID:25888790

  3. Capacitive proximity sensor

    DOEpatents

    Kronberg, James W.

    1994-01-01

    A proximity sensor based on a closed field circuit. The circuit comprises a ring oscillator using a symmetrical array of plates that creates an oscillating displacement current. The displacement current varies as a function of the proximity of objects to the plate array. Preferably the plates are in the form of a group of three pair of symmetric plates having a common center, arranged in a hexagonal pattern with opposing plates linked as a pair. The sensor produces logic level pulses suitable for interfacing with a computer or process controller. The proximity sensor can be incorporated into a load cell, a differential pressure gauge, or a device for measuring the consistency of a characteristic of a material where a variation in the consistency causes the dielectric constant of the material to change.

  4. Capacitive proximity sensor

    DOEpatents

    Kronberg, J.W.

    1994-05-31

    A proximity sensor based on a closed field circuit is disclosed. The circuit comprises a ring oscillator using a symmetrical array of plates that creates an oscillating displacement current. The displacement current varies as a function of the proximity of objects to the plate array. Preferably the plates are in the form of a group of three pair of symmetric plates having a common center, arranged in a hexagonal pattern with opposing plates linked as a pair. The sensor produces logic level pulses suitable for interfacing with a computer or process controller. The proximity sensor can be incorporated into a load cell, a differential pressure gauge, or a device for measuring the consistency of a characteristic of a material where a variation in the consistency causes the dielectric constant of the material to change. 14 figs.

  5. Unusual proximal tibiofibular synostosis.

    PubMed

    Takai, S; Yoshino, N; Hirasawa, Y

    1999-01-01

    Proximal tibiofibular synostosis without multiple hereditary exostosis is extremely rare and only 7 cases have been reported in the literature. All of the previously reported cases accompanied deformities such as distal positioning of the proximal tibiofibular joint, leg length discrepancy, bowing of the fibula, and valgus deformity of the knee. The present case of a 24-year-old man had neither a history of trauma nor deformity around the knee. Therefore, it was suggested that this type of synostosis occurred after epiphyseal plate closure. PMID:10741527

  6. Close proximity gunshot residues.

    PubMed

    Thornton, J I

    1986-04-01

    Intuitively, a hand held in close proximity to a firearm at the instant of discharge will intercept a significant amount of gunshot residue, even though the hand did not actually come into contact with the weapon. There is, however, little information specifically described in the forensic science literature concerning the residue levels which might be encountered in such an instance. The present work confirms that antimony levels consistent with an individual having fired or handled a firearm may be intercepted by a hand held in close proximity. PMID:3711843

  7. XQL and Proximal Nodes.

    ERIC Educational Resources Information Center

    Baeza-Yates, Ricardo; Navarro, Gonzalo

    2002-01-01

    Discussion of models that have been developed to structure text documents for information retrieval focuses on XML and its proposed query language XQL. Considers efficiency of the query engine and shows that an already existing model, Proximal Nodes, can be used as an efficient query engine behind an XQL front-end. (Author/LRW)

  8. Proximal tibiofibular synostosis.

    PubMed

    Gamble, J G

    1984-03-01

    A case of proximal tibiofibular synostosis with a 10-year follow-up is presented. The lesion was documented roentgenographically when the patient was 3 years of age and when she became symptomatic at 13 years of age after vigorous running. The symptoms were successfully treated with custom-molded shoe orthotics. PMID:6699166

  9. Proximate Analysis of Coal

    ERIC Educational Resources Information Center

    Donahue, Craig J.; Rais, Elizabeth A.

    2009-01-01

    This lab experiment illustrates the use of thermogravimetric analysis (TGA) to perform proximate analysis on a series of coal samples of different rank. Peat and coke are also examined. A total of four exercises are described. These are dry exercises as students interpret previously recorded scans. The weight percent moisture, volatile matter,…

  10. Steerable Capacitive Proximity Sensor

    NASA Technical Reports Server (NTRS)

    Jenstrom, Del T.; Mcconnell, Robert L.

    1994-01-01

    Steerable capacitive proximity sensor of "capaciflector" type based partly on sensing units described in GSC-13377 and GSC-13475. Position of maximum sensitivity adjusted without moving sensor. Voltage of each driven shield adjusted separately to concentrate sensing electric field more toward one side or other.

  11. Subacute diabetic proximal neuropathy

    NASA Technical Reports Server (NTRS)

    Pascoe, M. K.; Low, P. A.; Windebank, A. J.; Litchy, W. J.

    1997-01-01

    OBJECTIVE: To evaluate the clinical, electrophysiologic, autonomic, and neuropathologic characteristics and the natural history of subacute diabetic proximal neuropathy and its response to immunotherapy. MATERIAL AND METHODS: For the 12-year period from 1983 to 1995, we conducted a retrospective review of medical records of Mayo Clinic patients with diabetes who had subacute onset and progression of proximal weakness. The responses of treated versus untreated patients were compared statistically. RESULTS: During the designated study period, 44 patients with subacute diabetic proximal neuropathy were encountered. Most patients were middle-aged or elderly, and no sex preponderance was noted. The proximal muscle weakness often was associated with reduced or absent lower extremity reflexes. Associated weight loss was a common finding. Frequently, patients had some evidence of demyelination on nerve conduction studies, but it invariably was accompanied by concomitant axonal degeneration. The cerebrospinal fluid protein concentration was usually increased. Diffuse and substantial autonomic failure was generally present. In most cases, a sural nerve biopsy specimen suggested demyelination, although evidence of an inflammatory infiltrate was less common. Of 12 patients who received treatment (with prednisone, intravenous immune globulin, or plasma exchange), 9 had improvement of their conditions, but 17 of 29 untreated patients (59%) with follow-up also eventually had improvement, albeit at a much slower rate. Improvement was usually incomplete. CONCLUSION: We suggest that the entity of subacute diabetic proximal neuropathy is an extensive and severe variant of bilateral lumbosacral radiculoplexopathy, with some features suggestive of an immune-mediated cause. It differs from chronic inflammatory demyelinating polyradiculoneuropathy in that most cases have a more restricted distribution and seem to be monophasic and self-limiting. The efficacy of immunotherapy is unproved

  12. Proximity Networks and Epidemics

    NASA Astrophysics Data System (ADS)

    Guclu, Hasan; Toroczkai, Zoltán

    2007-03-01

    We presented the basis of a framework to account for the dynamics of contacts in epidemic processes, through the notion of dynamic proximity graphs. By varying the integration time-parameter T, which is the period of infectivity one can give a simple account for some of the differences in the observed contact networks for different diseases, such as smallpox, or AIDS. Our simplistic model also seems to shed some light on the shape of the degree distribution of the measured people-people contact network from the EPISIM data. We certainly do not claim that the simplistic graph integration model above is a good model for dynamic contact graphs. It only contains the essential ingredients for such processes to produce a qualitative agreement with some observations. We expect that further refinements and extensions to this picture, in particular deriving the link-probabilities in the dynamic proximity graph from more realistic contact dynamics should improve the agreement between models and data.

  13. Proximal Point Methods Revisited

    NASA Astrophysics Data System (ADS)

    Boikanyo, Oganeditse A.; Moroşanu, Gheorghe

    2011-09-01

    The proximal point methods have been widely used in the last decades to approximate the solutions of nonlinear equations associated with monotone operators. Inspired by the iterative procedure defined by B. Martinet (1970), R.T. Rockafellar introduced in 1976 the so-called proximal point algorithm (PPA) for a general maximal monotone operator. The sequence generated by this iterative method is weakly convergent under appropriate conditions, but not necessarily strongly convergent, as proved by O. Güler (1991). This fact explains the introduction of different modified versions of the PPA which generate strongly convergent sequences under appropriate conditions, including the contraction-PPA defined by H.K. Xu in 2002. Here we discuss Xu's modified PPA as well as some of its generalizations. Special attention is paid to the computational errors, in particular the original Rockafellar summability assumption is replaced by the condition that the error sequence converges to zero strongly.

  14. Distributed proximity sensor system

    NASA Technical Reports Server (NTRS)

    Lee, Sukhan (Inventor)

    1988-01-01

    The invention relates to sensors embedded on the surface of a robot hand, or other moving member. By distributing proximity sensors capable of detecting distances and angles to points on the surface of an object, information is obtained for achieving noncontacting shape and distance perception, i.e., for automatic determination of the object's shape, direction, and distance, as well as the orientation of the object relative to the robot hand or other moving member.

  15. Gastrin decreases Na+,K+-ATPase activity via a PI 3-kinase- and PKC-dependent pathway in human renal proximal tubule cells.

    PubMed

    Liu, Tianbing; Konkalmatt, Prasad R; Yang, Yu; Jose, Pedro A

    2016-04-01

    The natriuretic effect of gastrin suggests a role in the coordinated regulation of sodium balance by the gastrointestinal tract and the kidney. The renal molecular targets and signal transduction pathways for such an effect of gastrin are largely unknown. Recently, we reported that gastrin induces NHE3 phosphorylation and internalization via phosphatidylinositol (PI) 3-kinase and PKCα. In this study, we show that gastrin induced the phosphorylation of human Na(+),K(+)-ATPase at serine 16, resulting in its endocytosis via Rab5 and Rab7 endosomes. The gastrin-stimulated phosphorylation of Na(+),K(+)-ATPase was dependent on PI 3-kinase because the phosphorylation was blocked by the PI 3-kinase inhibitor wortmannin. The phosphorylation of Na(+),K(+)-ATPase was also blocked by chelerythrine, a pan-PKC inhibitor, Gö-6976, a conventional PKC (cPKC) inhibitor, and BAPTA-AM, an intracellular calcium chelator, suggesting the importance of cPKC and intracellular calcium in the gastrin signaling pathway. The gastrin-mediated phosphorylation of Na(+),K(+)-ATPase was also inhibited by U-73122, a phospholipase C (PLC) inhibitor. These results suggest that gastrin regulates sodium hydrogen exchanger and pump in renal proximal tubule cells at the apical and basolateral membranes. PMID:26786777

  16. Proximity networks and epidemics

    NASA Astrophysics Data System (ADS)

    Toroczkai, Zoltán; Guclu, Hasan

    2007-05-01

    Disease spread in most biological populations requires the proximity of agents. In populations where the individuals have spatial mobility, the contact graph is generated by the “collision dynamics” of the agents, and thus the evolution of epidemics couples directly to the spatial dynamics of the population. We first briefly review the properties and the methodology of an agent-based simulation (EPISIMS) to model disease spread in realistic urban dynamic contact networks. Using the data generated by this simulation, we introduce the notion of dynamic proximity networks which takes into account the relevant time-scales for disease spread: contact duration, infectivity period, and rate of contact creation. This approach promises to be a good candidate for a unified treatment of epidemic types that are driven by agent collision dynamics. In particular, using a simple model, we show that it can account for the observed qualitative differences between the degree distributions of contact graphs of diseases with short infectivity period (such as air-transmitted diseases) or long infectivity periods (such as HIV).

  17. Echosonography with proximity sensors

    NASA Astrophysics Data System (ADS)

    Thaisiam, W.; Laithong, T.; Meekhun, S.; Chaiwathyothin, N.; Thanlarp, P.; Danworaphong, S.

    2013-03-01

    We propose the use of a commercial ultrasonic proximity sensor kit for profiling an altitude-varying surface by employing echosonography. The proximity sensor kit, two identical transducers together with its dedicated operating circuit, is used as a profiler for the construction of an image. Ultrasonic pulses are emitted from one of the transducers and received by the other. The time duration between the pulses allows us to determine the traveling distance of each pulse. In the experiment, the circuit is used with the addition of two copper wires for directing the outgoing and incoming signals to an oscilloscope. The time of flight of ultrasonic pulses can thus be determined. Square grids of 5 × 5 cm2 are made from fishing lines, forming pixels in the image. The grids are designed to hold the detection unit in place, about 30 cm above a flat surface. The surface to be imaged is constructed to be height varying and placed on the flat surface underneath the grids. Our result shows that an image of the profiled surface can be created by varying the location of the detection unit along the grid. We also investigate the deviation in relation to the time of flight of the ultrasonic pulse. Such an experiment should be valuable for conveying the concept of ultrasonic imaging to physical and medical science undergraduate students. Due to its simplicity, the setup could be made in any undergraduate laboratory relatively inexpensively and it requires no complex parts. The results illustrate the concept of echosonography.

  18. The different positioning of the proximal sequence element in the Xenopus RNA polymerase II and III snRNA promoters is a key determinant which confers RNA polymerase III specificity.

    PubMed Central

    Lescure, A; Carbon, P; Krol, A

    1991-01-01

    We and others have previously described the TATA motif as a major determinant for Pol III specificity of the U6 promoter. Surprisingly, however, the data documented here show that the sole introduction of a TATA sequence into a U1 Pol II snRNA gene is not sufficient to confer Pol III transcription. Rather, this promoter element can mediate optimal Pol III transcription only if the PSE, the second promoter element, is shifted 4 bp upstream of the position it occupies in Pol II snRNA genes. As a result, the PSE-TATA-start site spacing introduced into the U1 Pol II gene is identical to that of the U6 gene and is strictly required to produce properly initiated Pol III transcripts. Thus, Pol II and Pol III PSEs, although similar in sequence, are not positionally equivalent. Competitive experiments raise the possibility that vertebrate U6 genes contain other, as yet unidentified, promoter elements. Images PMID:2011518

  19. Some Properties of Fuzzy Soft Proximity Spaces

    PubMed Central

    Demir, İzzettin; Özbakır, Oya Bedre

    2015-01-01

    We study the fuzzy soft proximity spaces in Katsaras's sense. First, we show how a fuzzy soft topology is derived from a fuzzy soft proximity. Also, we define the notion of fuzzy soft δ-neighborhood in the fuzzy soft proximity space which offers an alternative approach to the study of fuzzy soft proximity spaces. Later, we obtain the initial fuzzy soft proximity determined by a family of fuzzy soft proximities. Finally, we investigate relationship between fuzzy soft proximities and proximities. PMID:25793224

  20. Tools for proximal soil sensing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Proximal soil sensing (i.e. near-surface geophysical methods) are used to study soil phenomena across spatial scales. Geophysical methods exploit contrasts in physical properties (dielectric permittivity, apparent electrical conductivity or resistivity, magnetic susceptibility) to indirectly measur...

  1. Hirayama Disease with Proximal Involvement.

    PubMed

    Kim, Jinil; Kim, Yuntae; Kim, Sooa; Oh, Kiyoung

    2016-10-01

    Hirayama disease is a slowly progressing benign motor neuron disease that affects the distal upper limb. A 29-year-old man visited the hospital with a 1-year history of weakened left proximal upper limb. He was diagnosed with Hirayama disease 9 years ago, while there was no further progression of the muscle weakness afterward. Atrophy and weakness was detected in proximal upper limb muscles. Magnetic resonance imaging and somatosensory evoked potentials were normal. Needle electromyography showed abnormal findings in proximal upper limb muscles. Our patient had Hirayama disease involving the proximal portion through secondary progression. Clinical manifestation and accurate electromyography may be useful for diagnosis. Rare cases with progression patterns as described here are helpful and have clinical meaning for clinicians. PMID:27550499

  2. Cubesat Proximity Operations Demonstration (CPOD)

    NASA Technical Reports Server (NTRS)

    Villa, Marco; Martinez, Andres; Petro, Andrew

    2015-01-01

    The CubeSat Proximity Operations Demonstration (CPOD) project will demonstrate rendezvous, proximity operations and docking (RPOD) using two 3-unit (3U) CubeSats. Each CubeSat is a satellite with the dimensions 4 inches x 4 inches x 13 inches (10 centimeters x 10 centimeters x 33 centimeters) and weighing approximately 11 pounds (5 kilograms). This flight demonstration will validate and characterize many new miniature low-power proximity operations technologies applicable to future missions. This mission will advance the state of the art in nanosatellite attitude determination,navigation and control systems, in addition to demonstrating relative navigation capabilities.The two CPOD satellites are scheduled to be launched together to low-Earth orbit no earlier than Dec. 1, 2015.

  3. Geographic Proximity and Enrollment Competition.

    ERIC Educational Resources Information Center

    Zammuto, Raymond F.

    The use of a measure of geographic proximity to help explain enrollment competition among postsecondary institutions was investigated. The measure, the number of miles between institutions, was obtained by determining the longitude and latitude coordinates for about 99% of the schools in the Higher Education General Information System universe.…

  4. Driven shielding capacitive proximity sensor

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor); McConnell, Robert L. (Inventor)

    2000-01-01

    A capacitive proximity sensing element, backed by a reflector driven at the same voltage as and in phase with the sensor, is used to reflect the field lines away from a grounded robot arm towards an intruding object, thus dramatically increasing the sensor's range and sensitivity.

  5. Fiber-optic proximity sensor

    NASA Technical Reports Server (NTRS)

    Bejczy, A. K.; Hermann, W. A.; Primus, H. C.

    1980-01-01

    Proximity sensor for mechanical hand of remote manipulator incorporates fiber optics to conduct signals between light source and light detector. Fiber optics are not prone to noise from electromagnetic interference and radio-frequency interference as are sensors using long electrical cables.

  6. Symmetry-based reciprocity: evolutionary constraints on a proximate mechanism

    PubMed Central

    Campennì, Marco

    2016-01-01

    Background. While the evolution of reciprocal cooperation has attracted an enormous attention, the proximate mechanisms underlying the ability of animals to cooperate reciprocally are comparatively neglected. Symmetry-based reciprocity is a hypothetical proximate mechanism that has been suggested to be widespread among cognitively unsophisticated animals. Methods. We developed two agent-based models of symmetry-based reciprocity (one relying on an arbitrary tag and the other on interindividual proximity) and tested their ability both to reproduce significant emergent features of cooperation in group living animals and to promote the evolution of cooperation. Results. Populations formed by agents adopting symmetry-based reciprocity showed differentiated “social relationships” and a positive correlation between cooperation given and received: two common aspects of animal cooperation. However, when reproduction and selection across multiple generations were added to the models, agents adopting symmetry-based reciprocity were outcompeted by selfish agents that never cooperated. Discussion. In order to evolve, hypothetical proximate mechanisms must be able to stand competition from alternative strategies. While the results of our simulations require confirmation using analytical methods, we provisionally suggest symmetry-based reciprocity is to be abandoned as a possible proximate mechanism underlying the ability of animals to reciprocate cooperative interactions. PMID:26998412

  7. Micropower RF material proximity sensor

    DOEpatents

    McEwan, Thomas E.

    1998-01-01

    A level detector or proximity detector for materials capable of sensing through plastic container walls or encapsulating materials is of the sensor. Thus, it can be used in corrosive environments, as well as in a wide variety of applications. An antenna has a characteristic impedance which depends on the materials in proximity to the antenna. An RF oscillator, which includes the antenna and is based on a single transistor in a Colpitt's configuration, produces an oscillating signal. A detector is coupled to the oscillator which signals changes in the oscillating signal caused by changes in the materials in proximity to the antenna. The oscillator is turned on and off at a pulse repetition frequency with a low duty cycle to conserve power. The antenna consists of a straight monopole about one-quarter wavelength long at the nominal frequency of the oscillator. The antenna may be horizontally disposed on a container and very accurately detects the fill level within the container as the material inside the container reaches the level of the antenna.

  8. Micropower RF material proximity sensor

    DOEpatents

    McEwan, T.E.

    1998-11-10

    A level detector or proximity detector for materials capable of sensing through plastic container walls or encapsulating materials is disclosed. Thus, it can be used in corrosive environments, as well as in a wide variety of applications. An antenna has a characteristic impedance which depends on the materials in proximity to the antenna. An RF oscillator, which includes the antenna and is based on a single transistor in a Colpitt`s configuration, produces an oscillating signal. A detector is coupled to the oscillator which signals changes in the oscillating signal caused by changes in the materials in proximity to the antenna. The oscillator is turned on and off at a pulse repetition frequency with a low duty cycle to conserve power. The antenna consists of a straight monopole about one-quarter wavelength long at the nominal frequency of the oscillator. The antenna may be horizontally disposed on a container and very accurately detects the fill level within the container as the material inside the container reaches the level of the antenna. 5 figs.

  9. Plating of proximal humeral fractures.

    PubMed

    Martetschläger, Frank; Siebenlist, Sebastian; Weier, Michael; Sandmann, Gunther; Ahrens, Philipp; Braun, Karl; Elser, Florian; Stöckle, Ulrich; Freude, Thomas

    2012-11-01

    The optimal treatment for proximal humeral fractures is controversial. Few data exist concerning the influence of the surgical approach on the outcome. The purpose of this study was to evaluate the clinical and radiological outcomes of proximal humeral fractures treated with locking plate fixation through a deltopectoral vs an anterolateral deltoid-splitting approach. Of 86 patients who met the inclusion criteria, 70 were available for follow-up examination. Thirty-three patients were treated through a deltopectoral approach and 37 through an anterolateral deltoid-splitting approach. In all cases, open reduction and internal fixation with a PHILOS locking plate (Synthes, Umkirch, Germany) was performed. Clinical follow-up included evaluation of pain, shoulder mobility, and strength. Constant score and Disabilities of the Arm, Shoulder and Hand (DASH) score were assessed. A clinical neurological examination of the axillary nerve was also performed. Consolidation, reduction, and appearance of head necrosis were evaluated radiographically. After a mean follow-up of 33 months, Constant scores, DASH scores, and American Shoulder and Elbow Surgeons scores showed no significant differences between the groups. Clinical neurologic examination of the axillary nerve revealed no obvious damage to the nerve in either group. Deltopectoral and anterolateral detoid-splitting approaches for plate fixation of proximal humeral fractures are safe and provide similar clinical outcomes. The results of this study suggest that the approach can be chosen according to surgeon preference. PMID:23127451

  10. Promoting Sociolinguistic Competence in the Classroom Zone of Proximal Development

    ERIC Educational Resources Information Center

    van Compernolle, Remi A.; Williams, Lawrence

    2012-01-01

    This article explores the microgenetic development of learners' understanding of sociolinguistic variation in French during an instructional conversation (IC) that followed a language analysis task in which learners attempted to formulate hypotheses about the nature of language variation. During the IC, the instructor led students toward a…

  11. Loss of PDZ-adaptor protein NHERF2 affects membrane localization and cGMP- and [Ca2+]- but not cAMP-dependent regulation of Na+/H+ exchanger 3 in murine intestine

    PubMed Central

    Chen, Mingmin; Sultan, Ayesha; Cinar, Ayhan; Yeruva, Sunil; Riederer, Brigitte; Singh, Anurag Kumar; Li, Junhua; Bonhagen, Janina; Chen, Gang; Yun, Chris; Donowitz, Mark; Hogema, Boris; deJonge, Hugo; Seidler, Ursula

    2010-01-01

    Trafficking and regulation of the epithelial brush border membrane (BBM) Na+/H+ exchanger 3 (NHE3) in the intestine involves interaction with four different members of the NHERF family in a signal-dependent and possibly segment-specific fashion. The aim of this research was to study the role of NHERF2 (E3KARP) in intestinal NHE3 BBM localization and second messenger-mediated and receptor-mediated inhibition of NHE3. Immunolocalization of NHE3 in WT mice revealed predominant microvillar localization in jejunum and colon, a mixed distribution in the proximal ileum but localization near the terminal web in the distal ileum. The terminal web localization of NHE3 in the distal ileum correlated with reduced acid-activated NHE3 activity (fluorometrically assessed). NHERF2 ablation resulted in a shift of NHE3 to the microvilli and higher basal fluid absorption rates in the ileum, but no change in overall NHE3 protein or mRNA expression. Forskolin-induced NHE3 inhibition was preserved in the absence of NHERF2, whereas Ca2+ ionophore- or carbachol-mediated inhibition was abolished. Likewise, Escherichia coli heat stable enterotoxin peptide (STp) lost its inhibitory effect on intestinal NHE3. It is concluded that in native murine intestine, the NHE3 adaptor protein NHERF2 plays important roles in tethering NHE3 to a position near the terminal web and in second messenger inhibition of NHE3 in a signal- and segment-specific fashion, and is therefore an important regulator of intestinal fluid transport. PMID:20962002

  12. Proximate and polyphenolic characterization of cranberry pomace

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The proximate composition and identification and quantification of polyphenolic compounds in dried cranberry pomace were determined. Proximate analysis was conducted based on AOAC methods for moisture, protein, fat, and ash. Total carbohydrates were determined by the difference method. Polyphenolic ...

  13. Active Targets For Capacitive Proximity Sensors

    NASA Technical Reports Server (NTRS)

    Jenstrom, Del T.; Mcconnell, Robert L.

    1994-01-01

    Lightweight, low-power active targets devised for use with improved capacitive proximity sensors described in "Capacitive Proximity Sensor Has Longer Range" (GSC-13377), and "Capacitive Proximity Sensors With Additional Driven Shields" (GSC-13475). Active targets are short-distance electrostatic beacons; they generate known alternating electro-static fields used for alignment and/or to measure distances.

  14. The NHERF1 PDZ1 domain and IRBIT interact and mediate the activation of Na+/H+ exchanger 3 by ANG II.

    PubMed

    He, Peijian; Zhao, Luqing; No, Yi Ran; Karvar, Serhan; Yun, C Chris

    2016-08-01

    Na(+)/H(+) exchanger (NHE)3, a major Na(+) transporter in the luminal membrane of the proximal tubule, is subject to ANG II regulation in renal Na(+)/fluid absorption and blood pressure control. We have previously shown that inositol 1,4,5-trisphosphate receptor-binding protein released with inositol 1,4,5-trisphosphate (IRBIT) mediates ANG II-induced exocytosis of NHE3 in cultured proximal tubule epithelial cells. In searching for scaffold protein(s) that coordinates with IRBIT in NHE3 trafficking, we found that NHE regulatory factor (NHERF)1, NHE3, and IRBIT proteins were coexpressed in the same macrocomplexes and that loss of ANG II type 1 receptors decreased their expression in the renal brush-border membrane. We found that NHERF1 was required for ANG II-mediated forward trafficking and activation of NHE3 in cultured cells. ANG II induced a concomitant increase of NHERF1 interactions with NHE3 and IRBIT, which were abolished when the NHERF1 PDZ1 domain was removed. Overexpression of a yellow fluorescent protein-NHERF1 construct that lacks PDZ1, but not PDZ2, failed to exaggerate the ANG II-dependent increase of NHE3 expression in the apical membrane. Moreover, exogenous expression of PDZ1 exerted a dominant negative effect on NHE3 activation by ANG II. We further demonstrated that IRBIT was indispensable for the ANG II-provoked increase in NHERF1-NHE3 interactions and that phosphorylation of IRBIT at Ser(68) was necessary for the assembly of the NHEF1-IRBIT-NHE3 complex. Taken together, our findings suggest that NHERF1 mediates ANG II-induced activation of renal NHE3, which requires coordination between IRBIT and the NHERF1 PDZ1 domain in binding and transporting NHE3. PMID:27279487

  15. E4orf1 Enhances Glucose Uptake Independent of Proximal Insulin Signaling

    PubMed Central

    Na, Ha-Na; Hegde, Vijay; Dubuisson, Olga; Dhurandhar, Nikhil V.

    2016-01-01

    Impaired proximal insulin signaling is often present in diabetes. Hence, approaches to enhance glucose disposal independent of proximal insulin signaling are desirable. Evidence indicates that Adenovirus-derived E4orf1 protein may offer such an approach. This study determined if E4orf1 improves insulin sensitivity and downregulates proximal insulin signaling in vivo and enhances cellular glucose uptake independent of proximal insulin signaling in vitro. High fat fed mice were injected with a retrovirus plasmid expressing E4orf1, or a null vector. E4orf1 significantly improved insulin sensitivity in response to a glucose load. Yet, their proximal insulin signaling in fat depots was impaired, as indicated by reduced tyrosine phosphorylation of insulin receptor (IR), and significantly increased abundance of ectonucleotide pyrophosphatase/phosphodiesterase-1 (ENPP1). In 3T3-L1 pre-adipocytes E4orf1 expression impaired proximal insulin signaling. Whereas, treatment with rosiglitazone reduced ENPP1 abundance. Unaffected by IR-KD (insulin receptor knockdown) with siRNA, E4orf1 significantly up-regulated distal insulin signaling pathway and enhanced cellular glucose uptake. In vivo, E4orf1 impairs proximal insulin signaling in fat depots yet improves glycemic control. This is probably explained by the ability of E4orf1 to promote cellular glucose uptake independent of proximal insulin signaling. E4orf1 may provide a therapeutic template to enhance glucose disposal in the presence of impaired proximal insulin signaling. PMID:27537838

  16. E4orf1 Enhances Glucose Uptake Independent of Proximal Insulin Signaling.

    PubMed

    Na, Ha-Na; Hegde, Vijay; Dubuisson, Olga; Dhurandhar, Nikhil V

    2016-01-01

    Impaired proximal insulin signaling is often present in diabetes. Hence, approaches to enhance glucose disposal independent of proximal insulin signaling are desirable. Evidence indicates that Adenovirus-derived E4orf1 protein may offer such an approach. This study determined if E4orf1 improves insulin sensitivity and downregulates proximal insulin signaling in vivo and enhances cellular glucose uptake independent of proximal insulin signaling in vitro. High fat fed mice were injected with a retrovirus plasmid expressing E4orf1, or a null vector. E4orf1 significantly improved insulin sensitivity in response to a glucose load. Yet, their proximal insulin signaling in fat depots was impaired, as indicated by reduced tyrosine phosphorylation of insulin receptor (IR), and significantly increased abundance of ectonucleotide pyrophosphatase/phosphodiesterase-1 (ENPP1). In 3T3-L1 pre-adipocytes E4orf1 expression impaired proximal insulin signaling. Whereas, treatment with rosiglitazone reduced ENPP1 abundance. Unaffected by IR-KD (insulin receptor knockdown) with siRNA, E4orf1 significantly up-regulated distal insulin signaling pathway and enhanced cellular glucose uptake. In vivo, E4orf1 impairs proximal insulin signaling in fat depots yet improves glycemic control. This is probably explained by the ability of E4orf1 to promote cellular glucose uptake independent of proximal insulin signaling. E4orf1 may provide a therapeutic template to enhance glucose disposal in the presence of impaired proximal insulin signaling. PMID:27537838

  17. Protein Neighbors and Proximity Proteomics.

    PubMed

    Rees, Johanna S; Li, Xue-Wen; Perrett, Sarah; Lilley, Kathryn S; Jackson, Antony P

    2015-11-01

    Within cells, proteins can co-assemble into functionally integrated and spatially restricted multicomponent complexes. Often, the affinities between individual proteins are relatively weak, and proteins within such clusters may interact only indirectly with many of their other protein neighbors. This makes proteomic characterization difficult using methods such as immunoprecipitation or cross-linking. Recently, several groups have described the use of enzyme-catalyzed proximity labeling reagents that covalently tag the neighbors of a targeted protein with a small molecule such as fluorescein or biotin. The modified proteins can then be isolated by standard pulldown methods and identified by mass spectrometry. Here we will describe the techniques as well as their similarities and differences. We discuss their applications both to study protein assemblies and to provide a new way for characterizing organelle proteomes. We stress the importance of proteomic quantitation and independent target validation in such experiments. Furthermore, we suggest that there are biophysical and cell-biological principles that dictate the appropriateness of enzyme-catalyzed proximity labeling methods to address particular biological questions of interest. PMID:26355100

  18. Proximal bodies in hypersonic flow

    SciTech Connect

    Deiterding, Ralf; Laurence, Stuart J; Hornung, Hans G

    2007-01-01

    Hypersonic flows involving two or more bodies travelling in close proximity to one another are encountered in several important situations, both natural and man-made. The present work seeks to investigate one aspect of the resulting flow problem by exploring the forces experienced by a secondary body when it is within the domain of influence of a primary body travelling at hypersonic speeds. An analytical methodology based on the blast wave analogy is developed and used to predict the secondary force coefficients for simple geometries in both two and three dimensions. When the secondary body is entirely inside the primary shocked region, the nature of the lateral force coefficient is found to depend strongly on the relative size of the two bodies. For two spheres, the methodology predicts that the secondary body will experience an exclusively attractive lateral force if the secondary diameter is larger than one-sixth the primary diameter. The analytical results are compared with those from numerical simulations and reasonable agreement is observed if an appropriate normalization for the lateral displacement is used. Results from a series of experiments in the T5 hypervelocity shock tunnel are also presented and compared with perfect-gas numerical simulations, with good agreement. A new force-measurement technique for short-duration hypersonic facilities, enabling the experimental simulation of the proximal bodies problem, is described. This technique provides two independent means of measurement, and the agreement observed between the two gives a further degree of confidence in the results obtained.

  19. Protein Neighbors and Proximity Proteomics*

    PubMed Central

    Rees, Johanna S.; Li, Xue-Wen; Perrett, Sarah; Lilley, Kathryn S.; Jackson, Antony P.

    2015-01-01

    Within cells, proteins can co-assemble into functionally integrated and spatially restricted multicomponent complexes. Often, the affinities between individual proteins are relatively weak, and proteins within such clusters may interact only indirectly with many of their other protein neighbors. This makes proteomic characterization difficult using methods such as immunoprecipitation or cross-linking. Recently, several groups have described the use of enzyme-catalyzed proximity labeling reagents that covalently tag the neighbors of a targeted protein with a small molecule such as fluorescein or biotin. The modified proteins can then be isolated by standard pulldown methods and identified by mass spectrometry. Here we will describe the techniques as well as their similarities and differences. We discuss their applications both to study protein assemblies and to provide a new way for characterizing organelle proteomes. We stress the importance of proteomic quantitation and independent target validation in such experiments. Furthermore, we suggest that there are biophysical and cell-biological principles that dictate the appropriateness of enzyme-catalyzed proximity labeling methods to address particular biological questions of interest. PMID:26355100

  20. Resonant Frequency Spin Flipper for the nHe3 Experiment

    NASA Astrophysics Data System (ADS)

    Hayes, Christopher

    2014-03-01

    The n3He experiment, currently being installed on beamline-13 at ORNL's Spallation Neutron Source (SNS), is designed to measure the proton asymmetry associated with the interaction of neutrons with a gas of 3He via n +23He =13H +11H + 765 KeV . The experiment uses a Resonant Frequency Spin Flipper (RFSF) to flip the neutron spins. The spin flipper is similar to the one described by P.N. Seo et al. (PR ST Accel. Beams 11, 084701 2008) with significant improvements. Most important is the inclusion of a ``double cosine-theta'' winding pattern that provides a highly uniform interior field with no fringing. A critical feature of the coil is complex flux returns whose construction was made possible through the utilization of 3D print technology.

  1. Ash Aggregates in Proximal Settings

    NASA Astrophysics Data System (ADS)

    Porritt, L. A.; Russell, K.

    2012-12-01

    Ash aggregates are thought to have formed within and been deposited by the eruption column and plume and dilute density currents and their associated ash clouds. Moist, turbulent ash clouds are considered critical to ash aggregate formation by facilitating both collision and adhesion of particles. Consequently, they are most commonly found in distal deposits. Proximal deposits containing ash aggregates are less commonly observed but do occur. Here we describe two occurrences of vent proximal ash aggregate-rich deposits; the first within a kimberlite pipe where coated ash pellets and accretionary lapilli are found within the intra-vent sequence; and the second in a glaciovolcanic setting where cored pellets (armoured lapilli) occur within <1 km of the vent. The deposits within the A418 pipe, Diavik Diamond Mine, Canada, are the residual deposits within the conduit and vent of the volcano and are characterised by an abundance of ash aggregates. Coated ash pellets are dominant but are followed in abundance by ash pellets, accretionary lapilli and rare cored pellets. The coated ash pellets typically range from 1 - 5 mm in diameter and have core to rim ratios of approximately 10:1. The formation and preservation of these aggregates elucidates the style and nature of the explosive phase of kimberlite eruption at A418 (and other pipes?). First, these pyroclasts dictate the intensity of the kimberlite eruption; it must be energetic enough to cause intense fragmentation of the kimberlite to produce a substantial volume of very fine ash (<62 μm). Secondly, the ash aggregates indicate the involvement of moisture coupled with the presence of dilute expanded eruption clouds. The structure and distribution of these deposits throughout the kimberlite conduit demand that aggregation and deposition operate entirely within the confines of the vent; this indicates that aggregation is a rapid process. Ash aggregates within glaciovolcanic sequences are also rarely documented. The

  2. Efficient algorithms for proximity problems

    SciTech Connect

    Wee, Y.C.

    1989-01-01

    Computational geometry is currently a very active area of research in computer science because of its applications to VLSI design, database retrieval, robotics, pattern recognition, etc. The author studies a number of proximity problems which are fundamental in computational geometry. Optimal or improved sequential and parallel algorithms for these problems are presented. Along the way, some relations among the proximity problems are also established. Chapter 2 presents an O(N log{sup 2} N) time divide-and-conquer algorithm for solving the all pairs geographic nearest neighbors problem (GNN) for a set of N sites in the plane under any L{sub p} metric. Chapter 3 presents an O(N log N) divide-and-conquer algorithm for computing the angle restricted Voronoi diagram for a set of N sites in the plane. Chapter 4 introduces a new data structure for the dynamic version of GNN. Chapter 5 defines a new formalism called the quasi-valid range aggregation. This formalism leads to a new and simple method for reducing non-range query-like problems to range queries and often to orthogonal range queries, with immediate applications to the attracted neighbor and the planar all-pairs nearest neighbors problem. Chapter 6 introduces a new approach for the construction of the Voronoi diagram. Using this approach, we design an O(log N) time O (N) processor algorithm for constructing the Voronoi diagram with L{sub 1} and L. metrics on a CREW PRAM machine. Even though the GNN and the Delaunay triangulation (DT) do not have an inclusion relation, we show, using some range type queries, how to efficiently construct DT from the GNN relations over a constant number of angular ranges.

  3. Human Promoters Are Intrinsically Directional

    PubMed Central

    Duttke, Sascha H.C.; Lacadie, Scott A.; Ibrahim, Mahmoud M.; Glass, Christopher K.; Corcoran, David L.; Benner, Christopher; Heinz, Sven; Kadonaga, James T.; Ohler, Uwe

    2015-01-01

    Divergent transcription, in which reverse-oriented transcripts occur upstream of eukaryotic promoters in regions devoid of annotated genes, has been suggested to be a general property of active promoters. Here we show that the human basal RNA polymerase II transcriptional machinery and core promoter are inherently unidirectional, and that reverse-oriented transcripts originate from their own cognate reverse-directed core promoters. In vitro transcription analysis and mapping of nascent transcripts in cells revealed that sequences at reverse start sites are similar to those of their forward counterparts. The use of DNase I accessibility to define proximal promoter borders revealed that up to half of promoters are unidirectional and that unidirectional promoters are depleted at their upstream edges of reverse core promoter sequences and their associated chromatin features. Divergent transcription is thus not an inherent property of the transcription process, but rather the consequence of the presence of both forward- and reverse-directed core promoters. PMID:25639469

  4. Renin expression in renal proximal tubule.

    PubMed Central

    Moe, O W; Ujiie, K; Star, R A; Miller, R T; Widell, J; Alpern, R J; Henrich, W L

    1993-01-01

    Angiotensinogen, angiotensin-converting enzyme, and renin constitute the components of the renin-angiotensin system. The mammalian renal proximal tubule contains angiotensinogen, angiotensin-converting enzyme, and angiotensin receptors. Previous immunohistochemical studies describing the presence of renin in the proximal tubule could not distinguish synthesized renin from renin trapped from the glomerular filtrate. In the present study, we examined the presence of renin activity and mRNA in rabbit proximal tubule cells in primary culture and renin mRNA in microdissected proximal tubules. Renin activity was present in lysates of proximal tubule cells in primary culture. Cellular renin content in cultured proximal tubule cells was increased by incubation with 10(-5) M isoproterenol and 10(-5) M forskolin by 150 and 110%, respectively. In addition, renin transcripts were detected in poly(A)+ RNA from cultured proximal tubule cells by RNA blots under high stringency conditions. In microdissected tubules from normal rats, renin mRNA was not detectable with reverse transcription and polymerase chain reaction. However, in tubules from rats administered the angiotensinogen-converting-enzyme inhibitor, enalapril, renin was easily detected in the S2 segment of the proximal tubule. We postulate the existence of a local renin-angiotensin system that enables the proximal tubule to generate angiotensin II, thereby providing an autocrine system that could locally modulate NaHCO3 and NaCl absorption. Images PMID:7680667

  5. Optical proximity sensors for manipulators

    NASA Technical Reports Server (NTRS)

    Johnson, A. R.

    1973-01-01

    A breadboard optical proximity sensor intended for application to remotely operated manipulators has been constructed and evaluated in the laboratory. The sensing head was 20 mm x 15 mm x 10 mm in size, and could be made considerably smaller. Several such devices could be conveniently mounted on a manipulator hand, for example, to align the hand with an object. Type 1 and Type 2 optical configurations are discussed, Type 1 having a sharply defined sensitive volume, Type 2 an extended one. The sensitive volume can be placed at any distance between 1 cm and approximately 1 m by choice of a replaceable prism. The Type 1 lateral resolution was 0.5 mm on one axis and 5 mm perpendicular to it for a unit focused at 7.5 cm. The corresponding resolution in the axial direction was 2.4 cm, but improvement to 0.5 cm is possible. The effect of surface reflectivity is discussed and possible modes of application are suggested.

  6. Range gated strip proximity sensor

    DOEpatents

    McEwan, T.E.

    1996-12-03

    A range gated strip proximity sensor uses one set of sensor electronics and a distributed antenna or strip which extends along the perimeter to be sensed. A micro-power RF transmitter is coupled to the first end of the strip and transmits a sequence of RF pulses on the strip to produce a sensor field along the strip. A receiver is coupled to the second end of the strip, and generates a field reference signal in response to the sequence of pulse on the line combined with received electromagnetic energy from reflections in the field. The sensor signals comprise pulses of radio frequency signals having a duration of less than 10 nanoseconds, and a pulse repetition rate on the order of 1 to 10 MegaHertz or less. The duration of the radio frequency pulses is adjusted to control the range of the sensor. An RF detector feeds a filter capacitor in response to received pulses on the strip line to produce a field reference signal representing the average amplitude of the received pulses. When a received pulse is mixed with a received echo, the mixing causes a fluctuation in the amplitude of the field reference signal, providing a range-limited Doppler type signature of a field disturbance. 6 figs.

  7. Range gated strip proximity sensor

    DOEpatents

    McEwan, Thomas E.

    1996-01-01

    A range gated strip proximity sensor uses one set of sensor electronics and a distributed antenna or strip which extends along the perimeter to be sensed. A micro-power RF transmitter is coupled to the first end of the strip and transmits a sequence of RF pulses on the strip to produce a sensor field along the strip. A receiver is coupled to the second end of the strip, and generates a field reference signal in response to the sequence of pulse on the line combined with received electromagnetic energy from reflections in the field. The sensor signals comprise pulses of radio frequency signals having a duration of less than 10 nanoseconds, and a pulse repetition rate on the order of 1 to 10 MegaHertz or less. The duration of the radio frequency pulses is adjusted to control the range of the sensor. An RF detector feeds a filter capacitor in response to received pulses on the strip line to produce a field reference signal representing the average amplitude of the received pulses. When a received pulse is mixed with a received echo, the mixing causes a fluctuation in the amplitude of the field reference signal, providing a range-limited Doppler type signature of a field disturbance.

  8. Proximal Priority Laser Therapy: PPLT

    NASA Astrophysics Data System (ADS)

    Ohshiro, Toshio

    2004-09-01

    The author has, in the past, classified treatment methods for pain geometrically as point, line, two-dimensional, three-dimensional treatment and has used these over the years. However as a practitioner of western medicine, the author originally treated pain only directed at the painful site, and encountered cases where local treatment did not suffice. The author proved with SPECT and the Rand Phantom that treating the neck which is the midpoint of the brain, the center of the nervous system and the heart, the center of circulation, increased cerebral blood flow and also that laser emitted to neck will reach the spinal chord no matter from where on the neck the laser is emitted. From such research and 25 years of clinical experience, the author has created an anatomy based, systemic treatment method called the Proximal Priority Laser Therapy (PPLT) where not only the cerebral cortex, spinal chord and peripheral nerves are treated but also the tracts of blood vessels and lymph ducts are treated as well. Treatment method and cases are presented herein.

  9. Reticle processing induced proximity effects

    NASA Astrophysics Data System (ADS)

    Janssen, Maurice; de Kruif, Robert; Kiers, Ton

    2002-08-01

    Minimising Across Retical Line width Variation is a continuous challenge for each resolution node. Having tight critical dimension (CD) uniformity for a large variety of pitches is even more challenging. The causes of the reticle errors originate mainly from writing reticles at the edge of the write-tool's capabilities, and from manufacturing at the edge of etching and processing capabilities. These various reticle errors will subsequently lead to non-uniformity effects on wafer level. The reticle errors can be compensated for using technologies similar to those used to correct for optical proximity effects at wafer level. The errors can be small effects in the nanometer range like write noise or larger effects of 10 nm to 100 nm on reticle level from etching. Many effects that we see on reticle will be made visible on the wafer after exposure on a Step & Scan system. To visualise system performance one can use specific techniques such as selection of lines that are on target. In addition, with extensive measurement these reticle errors can be subtracted and thus removed from the final wafer result. For the investigation use is made of a reticle, which has a variation of 35 pitches for four line widths of 100 nm, 130 nm, 150 nm, and 170 nm at 1X. The reticle underwent extensive measurements, and its characteristics are described from these measurements. In addition, some wafer results are shown.

  10. Proximal Participation: A Pathway into Work

    ERIC Educational Resources Information Center

    Chan, Selena

    2013-01-01

    In a longitudinal case study of apprentices, the term proximal participation was coined to describe the entry process of young people, with unclear career destinations, into the trade of baking. This article unravels the significance of proximal participation in the decision-making processes of young people who enter a trade through initial…

  11. Proximate Sources of Collective Teacher Efficacy

    ERIC Educational Resources Information Center

    Adams, Curt M.; Forsyth, Patrick B.

    2006-01-01

    Purpose: Recent scholarship has augmented Bandura's theory underlying efficacy formation by pointing to more proximate sources of efficacy information involved in forming collective teacher efficacy. These proximate sources of efficacy information theoretically shape a teacher's perception of the teaching context, operationalizing the difficulty…

  12. Proximal bodies in hypersonic flow

    NASA Astrophysics Data System (ADS)

    Laurence, Stuart J.

    The problem of proximal bodies in hypersonic flow is encountered in several important situations, both natural and man-made. The present work seeks to investigate one aspect of this problem by exploring the forces experienced by a secondary body when some part of it is within the shocked region created by a primary body travelling at hypersonic speeds. An analytical methodology based on the blast wave analogy is developed and used to predict the secondary force coefficients for simple geometries in both two and three dimensions. When the secondary body is entirely inside the primary shocked region, the nature of the lateral coefficient is found to depend strongly on the relative size of the two bodies. For two spheres, the methodology predicts that the secondary body will experience an exclusively attractive lateral force if the secondary diameter is larger then one-sixth the primary diameter. The analytical results are compared with numerical simulations carried out using the AMROC software and good agreement is obtained if an appropriate normalization for the lateral displacement is used. Results from a series of experiments in the T5 hypervelocity shock tunnel are also presented and compared with perfect-gas numerical simulations, again with good agreement. In order to model this situation experimentally, a new force-measurement technique for short-duration hypersonic facilities has been developed, and results from the validation experiments are included. Finally, the analytical methodology is used to model two physical situations. First, the entry of a binary asteroid system into the Earth's atmosphere is simulated. Second, a model for a fragmenting meteoroid in a planetary atmosphere is developed, and simulations are carried out to determine whether the secondary scatter patterns in the Sikhote-Alin crater field may be attributed to aerodynamic interactions between fragments rather than to secondary fragmentation. It is found that while aerodynamic

  13. Design and ground verification of proximity operations

    NASA Astrophysics Data System (ADS)

    Tobias, A.; Ankersen, F.; Fehse, W.; Pauvert, C.; Pairot, J.

    This paper describes the approach to guidance, navigation, and control (GNC) design and verification for proximity operations. The most critical part of the rendezvous mission is the proximity operations phase when the distance between chaser and target is below approximately 20 m. Safety is the overriding consideration in the design of the GNC system. Requirements on the GNC system also stem from the allocation of performance between proximity operations and the mating process, docking, or capture for berthing. Whereas the design process follows a top down approach, the verification process goes bottom up in a stepwise way according to the development stage.

  14. [Proximity, intimacy and promiscuity in care].

    PubMed

    Flicourt, Nadia

    2015-04-01

    Lying at the heart of the intimacy of the other person, the nature of care supposes that the caregiver identifies the components resulting from the proximity and the invasion of the patient's personal space, where perceptions and representations give rise to reactive emotions and behaviour. Between modesty and nudity, proximity and promiscuity, caregivers have to adjust their approach of proper care, limiting the risks of intrusion. PMID:26043630

  15. An evaluation of proximal surface cleansing agents.

    PubMed

    Wolffe, G N

    1976-08-01

    The effectiveness of the Interspace brush, Inter-Dens, and waxed dental floss as proximal surface cleansing agents was compared in 35 subjects. Each subject used all three methods of cleansing in random order of selection. Statistical analysis of the results showed that there was no difference in the effectiveness of any one of these three agents. However, proximal surfaces of anterior teeth where cleaned more effectively than posterior teeth. The coronal half of the proximal surfaces was cleaned more effectively than the apical half and the facial half more effectively than the lingual half when Inter-Dens was used. Comparison of cleansing effectiveness between facial and lingual halves of proximal surfaces for the Interspace brush and waxed dental floss showed no significant difference. Mesial and distal proximal surfaces were cleaned with similar effectiveness. Plaque control was only satisfactory on approximately half of the proximal surfaces, though a wide variation occurred. Significantly lower plaque scores were found 1 week after the initial instruction session, irrespective of the agent used. The majority of subjects preferred Inter-Dens whilst waxed dental floss was the least-liked method of cleansing. PMID:1067276

  16. Proximity sensor system development. CRADA final report

    SciTech Connect

    Haley, D.C.; Pigoski, T.M.

    1998-01-01

    Lockheed Martin Energy Research Corporation (LMERC) and Merritt Systems, Inc. (MSI) entered into a Cooperative Research and Development Agreement (CRADA) for the development and demonstration of a compact, modular proximity sensing system suitable for application to a wide class of manipulator systems operated in support of environmental restoration and waste management activities. In teleoperated modes, proximity sensing provides the manipulator operator continuous information regarding the proximity of the manipulator to objects in the workspace. In teleoperated and robotic modes, proximity sensing provides added safety through the implementation of active whole arm collision avoidance capabilities. Oak Ridge National Laboratory (ORNL), managed by LMERC for the United States Department of Energy (DOE), has developed an application specific integrated circuit (ASIC) design for the electronics required to support a modular whole arm proximity sensing system based on the use of capacitive sensors developed at Sandia National Laboratories. The use of ASIC technology greatly reduces the size of the electronics required to support the selected sensor types allowing deployment of many small sensor nodes over a large area of the manipulator surface to provide maximum sensor coverage. The ASIC design also provides a communication interface to support sensor commands from and sensor data transmission to a distributed processing system which allows modular implementation and operation of the sensor system. MSI is a commercial small business specializing in proximity sensing systems based upon infrared and acoustic sensors.

  17. Adult and Child Development in the Zone of Proximal Development: Socratic Dialogue in a Playworld

    ERIC Educational Resources Information Center

    Ferholt, Beth; Lecusay, Robert

    2010-01-01

    This article analyses adult and child development in the zone of proximal development in an educational practice based in Vygotsky's theories of play: the playworld educational practice. The playworld educational practice is a central component of a Scandinavian play pedagogy that promotes shared responsibility amongst adults and children for…

  18. Proximal Junctional Kyphosis: Diagnosis, Pathogenesis, and Treatment

    PubMed Central

    Lee, Jaewon

    2016-01-01

    Proximal junctional kyphosis (PJK) is a common radiographic finding after long spinal fusion. A number of studies on the causes, risk factors, prevention, and treatment of PJK have been conducted. However, no clear definition of PJK has been established. In this paper, we aimed to clarify the diagnosis, prevention, and treatment of PJK by reviewing relevant papers that have been published to date. A literature search was conducted on PubMed using "proximal junctional", "proximal junctional kyphosis", and "proximal junctional failure" as search keywords. Only studies that were published in English were included in this study. The incidence of PJK ranges from 5% to 46%, and it has been reported that 66% of cases occur 3 months after surgery and approximately 80% occur within 18 months. A number of studies have reported that there is no significantly different clinical outcome between PJK patients and non-PJK patients. One study showed that PJK patients expressed more pain than non-PJK patients. However, recent studies focused on proximal junctional failure (PJF), which is accepted as a severe form of PJK. PJF showed significant adverse impact in clinical aspect such as pain, neurologic deficit, ambulatory difficulties, and social isolation. Numerous previous studies have identified various risk factors and reported on the treatment and prevention of PJK. Based on these studies, we determined the clinical significance and impact of PJK. In addition, it is important to find a strategic approach to the proper treatment of PJK. PMID:27340542

  19. Proximity assays for sensitive quantification of proteins.

    PubMed

    Greenwood, Christina; Ruff, David; Kirvell, Sara; Johnson, Gemma; Dhillon, Harvinder S; Bustin, Stephen A

    2015-06-01

    Proximity assays are immunohistochemical tools that utilise two or more DNA-tagged aptamers or antibodies binding in close proximity to the same protein or protein complex. Amplification by PCR or isothermal methods and hybridisation of a labelled probe to its DNA target generates a signal that enables sensitive and robust detection of proteins, protein modifications or protein-protein interactions. Assays can be carried out in homogeneous or solid phase formats and in situ assays can visualise single protein molecules or complexes with high spatial accuracy. These properties highlight the potential of proximity assays in research, diagnostic, pharmacological and many other applications that require sensitive, specific and accurate assessments of protein expression. PMID:27077033

  20. Jet Diffusion in Proximity of a Wall

    NASA Technical Reports Server (NTRS)

    Kuechemann, D.

    1949-01-01

    When auxiliary jet engines are installed on airframes; as well as in some new designs, the jet engines are mounted in such a way that the jet stream exhausts in close proximity to the fuselage. This report deals with the behavior of the jet in close proximity to a two-dimensional surface. The experiments were made to find out whether the axially symmetric stream tends to approach the flat surface. This report is the last of a series of four partial test reports of the Goettingen program for the installation of jet engines, dated October 12, 1943. This report is the complement of the report on intake in close proximity to a wall.

  1. Proximity assays for sensitive quantification of proteins

    PubMed Central

    Greenwood, Christina; Ruff, David; Kirvell, Sara; Johnson, Gemma; Dhillon, Harvinder S.; Bustin, Stephen A.

    2015-01-01

    Proximity assays are immunohistochemical tools that utilise two or more DNA-tagged aptamers or antibodies binding in close proximity to the same protein or protein complex. Amplification by PCR or isothermal methods and hybridisation of a labelled probe to its DNA target generates a signal that enables sensitive and robust detection of proteins, protein modifications or protein–protein interactions. Assays can be carried out in homogeneous or solid phase formats and in situ assays can visualise single protein molecules or complexes with high spatial accuracy. These properties highlight the potential of proximity assays in research, diagnostic, pharmacological and many other applications that require sensitive, specific and accurate assessments of protein expression. PMID:27077033

  2. Infrared-Proximity-Sensor Modules For Robot

    NASA Technical Reports Server (NTRS)

    Parton, William; Wegerif, Daniel; Rosinski, Douglas

    1995-01-01

    Collision-avoidance system for articulated robot manipulators uses infrared proximity sensors grouped together in array of sensor modules. Sensor modules, called "sensorCells," distributed processing board-level products for acquiring data from proximity-sensors strategically mounted on robot manipulators. Each sensorCell self-contained and consists of multiple sensing elements, discrete electronics, microcontroller and communications components. Modules connected to central control computer by redundant serial digital communication subsystem including both serial and a multi-drop bus. Detects objects made of various materials at distance of up to 50 cm. For some materials, such as thermal protection system tiles, detection range reduced to approximately 20 cm.

  3. Goal-Proximity Decision-Making

    ERIC Educational Resources Information Center

    Veksler, Vladislav D.; Gray, Wayne D.; Schoelles, Michael J.

    2013-01-01

    Reinforcement learning (RL) models of decision-making cannot account for human decisions in the absence of prior reward or punishment. We propose a mechanism for choosing among available options based on goal-option association strengths, where association strengths between objects represent previously experienced object proximity. The proposed…

  4. Vortices in normal part of proximity system

    DOE PAGESBeta

    Kogan, V. G.

    2015-05-26

    It is shown that the order parameter Δ induced in the normal part of superconductor-normal-superconductor proximity system is modulated in the magnetic field differently from vortices in bulk superconductors. Whereas Δ turns zero at vortex centers, the magnetic structure of these vortices differs from that of Abrikosov's.

  5. Email Keypals in Zone of Proximal Development.

    ERIC Educational Resources Information Center

    Kaufman, Lionel M., Jr.

    This study analyzed the discourse of electronic mail (e-mail) exchanges between students of English as a second language (ESL) and other ESL learners from other cultures and at varying proficiency levels (keypals), focusing on what these exchanges may reveal about learners' progress through the "Zone of Proximal Development," a Vygotskian concept…

  6. Laparoscopic Proximal Gastrectomy With Gastric Tube Reconstruction

    PubMed Central

    Shiraishi, Norio; Toujigamori, Manabu; Shiroshita, Hidefumi; Etoh, Tsuyoshi; Inomata, Masafumi

    2016-01-01

    Background and Objectives: There is no standardized method of reconstruction in laparoscopic proximal gastrectomy (LPG). We present a novel technique of reconstruction with a long, narrow gastric tube in LPG for early gastric cancer (EGC). Methods: During the laparoscopic procedure, the upper part of the stomach is fully mobilized with perigastric and suprapancreatic lymphadenectomy, and then the abdominal esophagus is transected. After a minilaparotomy is created, the entire stomach is pulled outside. A long, narrow gastric tube (20 cm long, 3 cm wide) is created with a linear stapler. The proximal part of the gastric tube is formed into a cobra head shape for esophagogastric tube anastomosis, which is then performed with a 45-mm linear stapler under laparoscopic view. The end of the esophagus is fixed on the gastric tube to prevent postoperative esophageal reflux. Results: Thirteen patients with early proximal gastric cancer underwent the procedure. The mean operative time was 283 min, and median blood loss was 63 ml. There were no conversions to open surgery, and no intraoperative complications. Conclusion: This new technique of reconstruction after LPG is simple and feasible. The procedure has the potential of becoming a standard reconstruction technique after LPG for proximal EGC. PMID:27547027

  7. Current status of proximal gastric vagotomy.

    PubMed Central

    Schirmer, B D

    1989-01-01

    Proximal gastric vagotomy is nearing its twentieth year in clinical use as an operation for peptic ulcer disease. No other acid-reducing operation has undergone as much scrutiny or study. At this time, the evidence of such studies and long-term follow-up strongly supports the use of proximal gastric vagotomy as the treatment of choice for chronic duodenal ulcer in patients who have failed medical therapy. Its application in treating the complications of peptic ulcer disease, which recently have come to represent an increasingly greater percentage of all operations done for peptic ulcer disease, is well-tested. However, initial series suggest that it should probably occupy a prominent role in treating some of these complications, particularly in selected patients, in the future. The operation has the well-documented ability to reduce gastric acid production, not inhibit gastric bicarbonate production, and also minimally inhibit gastric motility. The combination of these physiologic results after proximal gastric vagotomy, along with preservation of the normal antropyloroduodenal mechanism of gastrointestinal control, serve to allow patients with proximal gastric vagotomy the improved benefits of significantly fewer severe gastrointestinal side effects than are seen after other operations for peptic ulcer disease. PMID:2644897

  8. Hybrid Repair of Proximal Subclavian Artery Aneurysm

    PubMed Central

    Morimoto, Kazuki; Fukuda, Tetsuya; Iba, Hiroshi; Tanaka, Hiroshi; Sasaki, Hiroaki; Minatoya, Kenji; Kobayashi, Junjiro

    2015-01-01

    Objective: Conventional open repair for proximal subclavian artery aneurysms (SCAAs) requires cardiopulmonary bypass. However, patients with proximal SCAA can be treated with hybrid repair. Methods: Between 2007 and 2012, we performed hybrid repair to treat six consecutive patients with proximal SCAA (three left SCAAs, one right aberrant SCAA, two right SCAAs). Their median age was 73.5 [70–87] years, and the size of their aneurysm was 33.5 [30–45] mm. Thoracic endovascular aneurysm repair (TEVAR) only was used for one patient with left SCAA, TEVAR and supra-aortic bypass for two with left SCAA and one with right aberrant SCAA, and endovascular repair with reconstruction of the vertebral artery using the saphenous vein graft (SVG) for two with right SCAA. Results: The follow-up duration was 3.7 [0.2–6.8] years. There was no 30-day mortality and only one early complication consisting of a minor stroke after TEVAR for shaggy aorta. Two late deaths occurred, one caused by cerebral infarction due to occlusion of SVG to the dominant vertebral artery 2 months after the operation and the other by aortic dissection 5 years postoperatively. Conclusions: Hybrid repair can be a less-invasive alternative for proximal SCAA. Revascularization of neck vessels and TEVAR should be performed very carefully to prevent neurologic complications. PMID:26131027

  9. Traumatic proximal tibiofibular dislocation with neurovascular injury

    PubMed Central

    Veerappa, Lokesh A; Gopalakrishna, Chetan

    2012-01-01

    23 years old male presented with inferolateral dislocation of proximal tibiofibular joint associated with popliteal artery and common peroneal nerve injury. The extension of the injury to involve the interosseus membrane up to the distal tibiofibular joint. The association of popliteal artery injury is not reported before to the best of our knowledge. PMID:23162155

  10. Proximal humerus fractures in children and adolescents.

    PubMed

    Lefèvre, Y; Journeau, P; Angelliaume, A; Bouty, A; Dobremez, E

    2014-02-01

    Proximal humerus fractures are rare in paediatric traumatology. Metaphyseal fractures account for about 70% of cases and epiphyseal separation for the remaining 30%. The development and anatomy of the proximal humerus explain the various fracture types, displacements, and potential complications; and also help in interpreting the radiographic findings, most notably in young children. Physicians should be alert to the possibility of an underlying lesion or pathological fracture requiring appropriate diagnostic investigations, and they should consider child abuse in very young paediatric patients. Although the management of proximal humerus fractures remains controversial, the extraordinary remodelling potential of the proximal humerus in skeletally immature patients often allows non-operative treatment without prior reduction. When the displacement exceeds the remodelling potential suggested by the extent of impaction, angulation, and patient age, retrograde elastic stable intramedullary nailing (ESIN) provides effective stabilisation. As a result, the thoraco-brachial abduction cast is less often used, although this method remains a valid option. Retrograde ESIN must be performed by a surgeon who is thoroughly conversant with the fundamental underlying principles. Direct percutaneous pinning is a fall-back option when the surgeon's experience with ESIN is insufficient. Finally, open reduction is very rarely required and should be reserved for severely displaced fractures after failure of closed reduction. When these indications are followed, long-term outcomes are usually excellent, with prompt resumption of previous activities and a low rate of residual abnormalities. PMID:24394917

  11. Capacitive Proximity Sensors With Additional Driven Shields

    NASA Technical Reports Server (NTRS)

    Mcconnell, Robert L.

    1993-01-01

    Improved capacitive proximity sensors constructed by incorporating one or more additional driven shield(s). Sensitivity and range of sensor altered by adjusting driving signal(s) applied to shield(s). Includes sensing electrode and driven isolating shield that correspond to sensing electrode and driven shield.

  12. The Zone of Proximal "Teacher" Development

    ERIC Educational Resources Information Center

    Warford, Mark K.

    2011-01-01

    Toward the end of his short life, Lev Vygotsky found himself teaching teachers in a remote part of the USSR. Though his influence as a developmental psychologist is well-established, little is known about his approach to teacher development. This article applies the researcher's core concept, the zone of proximal development to teacher education.…

  13. Characteristics of He II Proximity Profiles

    NASA Astrophysics Data System (ADS)

    Zheng, Wei; Syphers, David; Meiksin, Avery; Kriss, Gerard A.; Schneider, Donald P.; York, Donald G.; Anderson, Scott F.

    2015-06-01

    The proximity profile in the spectra of z≈ 3 quasars, where fluxes extend blueward of the He ii Lyα wavelength 304 (1+z) Å, is one of the most important spectral features in the study of the intergalactic medium (IGM). Based on the Hubble Space Telescope spectra of 24 He ii quasars, we find that the majority of them display a proximity profile, corresponding to an ionization radius as large as 20 Mpc in the source's rest frame. In comparison with those in the H i spectra of the quasars at z ≈ 6, the He ii proximity effect is more prominent and is observed over a considerably longer period of reionization. The He ii proximity zone sizes decrease at higher redshifts, particularly at z\\gt 3.3. This trend is similar to that for H i, signaling an onset of He ii reionization at z≳ 4. For quasar SDSS1253+6817 (z = 3.48), the He ii absorption trough displays a gradual decline and serves as a good case for modeling the He ii reionization. To model such a broad profile requires a quasar radiation field whose energy distribution between 4 and 1 Rydberg is considerably harder than normally assumed. The UV continuum of this quasar is indeed exceptionally steep, and the He ii ionization level in the quasar vicinity is higher than the average level in the IGM. These results are evidence that a very hard EUV continuum from this quasar produces a large ionized zone around it. Distinct exceptions are the two brightest He ii quasars at z ≈ 2.8, for which no significant proximity profile is present, probably implying that they are very young.

  14. Painful Spastic Hip Dislocation: Proximal Femoral Resection

    PubMed Central

    Albiñana, Javier; Gonzalez-Moran, Gaspar

    2002-01-01

    The dislocated hip in a non-ambulatory child with spastic paresis tends to be a painful interference to sleep, sitting upright, and perineal care. Proximal femoral resection-interposition arthroplasty is one method of treatment for this condition. We reviewed eight hips, two bilateral cases, with a mean follow-up of 30 months. Clinical improvement was observed in all except one case, with respect to pain relief and sitting tolerance. Some proximal migration was observed in three cases, despite routine post-operative skeletal traction in all cases and careful soft tissue interposition. One case showed significant heterotopic ossification which restricted prolonged sitting. This patient needed some occasional medication for pain. PMID:12180614

  15. Isolated Proximal Tibiofibular Dislocation during Soccer

    PubMed Central

    Chiu, Casey; Sheele, Johnathan Michael

    2015-01-01

    Proximal tibiofibular dislocations are rarely encountered in the Emergency Department (ED). We present a case involving a man presenting to the ED with left knee pain after making a sharp left turn on the soccer field. His physical exam was only remarkable for tenderness over the lateral fibular head. His X-rays showed subtle abnormalities of the tibiofibular joint. The dislocation was reduced and the patient was discharged from the ED with orthopedic follow-up. PMID:26713164

  16. Large proximal ureteral stones: Ideal treatment modality?

    PubMed Central

    Kadyan, B.; Sabale, V.; Mane, D.; Satav, V.; Mulay, A.; Thakur, N.; Kankalia, S. P.

    2016-01-01

    Background and Purpose: Ideal treatment modality for patients with large impacted proximal ureteral stone remains controversial. We compared laparoscopic transperitoneal ureterolithotomy (Lap-TPUL) and semirigid ureteroscopy for large proximal ureteric stones to evaluate their efficacy and safety. Patients and Methods: From November 2012 to December 2014, we enrolled 122 patients with large (≥1.5 cm) proximal ureteral stone in the study. Patients were randomly divided into two groups: Group A (60 patients), retrograde ureteroscopic lithotripsy using a semirigid ureteroscope; Group B (62 patients), transperitoneal LU (Lap-TPUL). Results: The overall stone-free rate was 71.6% and 93.5% for Group A and Group B respectively (P = 0.008). Auxiliary procedure rate was higher in Group A than in Group B (27.3% vs. 5.6%). The complication rate was 11.2% in Group B versus 25% in Group A. Mean procedure time was higher in laparoscopy group as compared to ureterorenoscopy (URS) groups (84.07 ± 16.80 vs. 62.82 ± 12.71 min). Hospital stay was 4.16 ± 0.67 days in laparoscopy group and 1.18 ± 0.38 days in URS group (P < 0.0001). Conclusion: Laparoscopic transperitoneal ureterolithotomy is a minimally invasive, safe and effective treatment modality and should be recommended to all patients of impacted large proximal stones, which are not amenable to URS or extracorporeal shock-wave lithotripsy or as a primary modality of choice especially if patient is otherwise candidate for open surgery. PMID:27141190

  17. Proximal Sciatic Nerve Intraneural Ganglion Cyst

    PubMed Central

    Swartz, Karin R.; Wilson, Dianne; Boland, Michael; Fee, Dominic B.

    2009-01-01

    Intraneural ganglion cysts are nonneoplastic, mucinous cysts within the epineurium of peripheral nerves which usually involve the peroneal nerve at the knee. A 37-year-old female presented with progressive left buttock and posterior thigh pain. Magnetic resonance imaging revealed a sciatic nerve mass at the sacral notch which was subsequently revealed to be an intraneural ganglion cyst. An intraneural ganglion cyst confined to the proximal sciatic nerve has only been reported once prior to 2009. PMID:20069041

  18. Transverse Stress Fracture of the Proximal Patella

    PubMed Central

    Atsumi, Satoru; Arai, Yuji; Kato, Ko; Nishimura, Akinobu; Nakazora, Shigeto; Nakagawa, Shuji; Ikoma, Kazuya; Fujiwara, Hiroyoshi; Sudo, Akihiro; Kubo, Toshikazu

    2016-01-01

    Abstract Among stress fractures associated with sports activities, patellar stress fracture is rare. Regarding patella stress fractures, so far only distal transverse or lateral longitudinal fractures have been reported, but there are no reports of transverse fractures occurring in the proximal patella. We describe an extremely rare case of transverse stress fracture of proximal patella in a 9-year-old athlete. A 9-year old boy, who participated in sports (sprints and Kendo) presented with left knee pain without any external injury. In plain radiographs, a fracture line was observed in the proximal 1/3 of the left patella, and a patella stress fracture was diagnosed. For treatment, because 7 months of conservative therapy showed no improvement, internal fixation was carried out using Acutrak screws, and bone union was thus achieved. Three months after the operation, he was able to return to his previous level of athletic sports activity. Regarding the mechanism of onset, it is believed that the causes are longitudinal traction force and patellofemoral contact pressure. On the other hand, the contact region of the patella with the femur changes with the flexion angle of the knee. In the current case, the fracture occurred at a site where the patella was in contact with the femur at a flexion angle of >90°, so it is believed that it occurred as a clinical condition from being subjected to repeated longitudinal traction force and patellofemoral contact pressure at a flexion angle of >90°, during the sports activities of sprints and Kendo. The nonunion of the transverse stress fracture of his proximal patella was successfully treated with internal fixation using Acutrak screws. PMID:26871789

  19. Proximal tibial fracture following total knee arthroplasty.

    PubMed

    Krause, Heike; Dunleavy, Kim

    2011-09-01

    The patient was a 74-year-old man, with a history of total knee arthoplasty 14 years earlier, after having sustained a pathological fracture of the proximal diaphysis of the left tibia following a fall. Given the unstable nature of the fracture and the severe osteolysis noted below the total knee arthroplasty, surgical management 1 day after the fall entailed packing cancellous bone graft into the defect and realigning the fracture. PMID:21885911

  20. Capacitive Proximity Sensor Has Longer Range

    NASA Technical Reports Server (NTRS)

    Vranish, John M.

    1992-01-01

    Capacitive proximity sensor on robot arm detects nearby object via capacitive effect of object on frequency of oscillator. Sensing element part of oscillator circuit operating at about 20 kHz. Total capacitance between sensing element and ground constitutes tuning capacitance of oscillator. Sensor circuit includes shield driven by replica of alternating voltage applied to sensing element. Driven shield concentrates sensing electrostatic field in exterior region to enhance sensitivity to object. Sensitivity and dynamic range has corresponding 12-to-1 improvement.

  1. Human proximal tubule cells form functional microtissues.

    PubMed

    Prange, Jenny A; Bieri, Manuela; Segerer, Stephan; Burger, Charlotte; Kaech, Andres; Moritz, Wolfgang; Devuyst, Olivier

    2016-04-01

    The epithelial cells lining the proximal tubules of the kidney mediate complex transport processes and are particularly vulnerable to drug toxicity. Drug toxicity studies are classically based on two-dimensional cultures of immortalized proximal tubular cells. Such immortalized cells are dedifferentiated, and lose transport properties (including saturable endocytic uptake) encountered in vivo. Generating differentiated, organotypic human microtissues would potentially alleviate these limitations and facilitate drug toxicity studies. Here, we describe the generation and characterization of kidney microtissues from immortalized (HK-2) and primary (HRPTEpiC) human renal proximal tubular epithelial cells under well-defined conditions. Microtissue cultures were done in hanging drop GravityPLUS™ culture plates and were characterized for morphology, proliferation and differentiation markers, and by monitoring the endocytic uptake of albumin. Kidney microtissues were successfully obtained by co-culturing HK-2 or HRPTEpiC cells with fibroblasts. The HK-2 microtissues formed highly proliferative, but dedifferentiated microtissues within 10 days of culture, while co-culture with fibroblasts yielded spherical structures already after 2 days. Low passage HRPTEpiC microtissues (mono- and co-culture) were less proliferative and expressed tissue-specific differentiation markers. Electron microscopy evidenced epithelial differentiation markers including microvilli, tight junctions, endosomes, and lysosomes in the co-cultured HRPTEpiC microtissues. The co-cultured HRPTEpiC microtissues showed specific uptake of albumin that could be inhibited by cadmium and gentamycin. In conclusion, we established a reliable hanging drop protocol to obtain functional kidney microtissues with proximal tubular epithelial cell lines. These microtissues could be used for high-throughput drug and toxicology screenings, with endocytosis as a functional readout. PMID:26676951

  2. Proximity induced supercurrent in multilayer graphene

    NASA Astrophysics Data System (ADS)

    Kanda, Akinobu; Goto, Hidenori; Tanaka, Sho; Nagai, Yukitoshi; Ootuka, Youiti; Odaka, Shunsuke; Miyazaki, Hisao; Tsukagoshi, Kazuhito

    2009-03-01

    We report experimental study on gate-dependent superconducting proximity effect in multilayer graphene. In our sample, multilayer graphene (MLG), obtained by the micromechanical cleavage of Kish graphite, is placed on a SiO2/p^+-Si substrate, and two superconducting (Ti/Al) electrodes are connected to the top of the MLG. Dependence of the critical supercurrent on MLG length and temperature will be discussed.

  3. Proximity sensing with wavelet generated video

    NASA Astrophysics Data System (ADS)

    Noel, Steven E.; Szu, Harold H.

    1998-10-01

    In this paper we introduce wavelet video processing of proximity sensor signals. Proximity sensing is required for a wide range of military and commercial applications, including weapon fuzzing, robotics, and automotive collision avoidance. While our proposed method temporarily increases signal dimension, it eventually performs data compression through the extraction of salient signal features. This data compression in turn reduces the necessary complexity of the remaining computational processing. We demonstrate our method of wavelet video processing via the proximity sensing of nearby objects through their Doppler shift. In doing this we perform a continuous wavelet transform on the Doppler signal, after subjecting it to a time-varying window. We then extract signal features from the resulting wavelet video, which we use as input to pattern recognition neural networks. The networks are trained to estimate the time- varying Doppler shift from the extracted features. We test the estimation performance of the networks, using different degrees of nonlinearity in the frequency shift over time and different levels of noise. We give the analytical result that the signal-to-noise enhancement of our proposed method is at least as good as the square root of the number of video frames, although more work is needed to completely quantify this. Real-time wavelet-based video processing and compression technology recently developed under the DOD WAVENET program offers an exciting opportunity to more fully investigate our proposed method.

  4. Gene teams with relaxed proximity constraint.

    PubMed

    Kim, Sun; Choi, Jeong-Hyeon; Yang, Jiong

    2005-01-01

    Functionally related genes co-evolve, probably due to the strong selection pressure in evolution. Thus we expect that they are present in multiple genomes. Physical proximity among genes, known as gene team, is a very useful concept to discover functionally related genes in multiple genomes. However, there are also many gene sets that do not preserve physical proximity. In this paper, we generalized the gene team model, that looks for gene clusters in a physically clustered form, to multiple genome cases with relaxed constraint. We propose a novel hybrid pattern model that combines the set and the sequential pattern models. Our model searches for gene clusters with and/or without physical proximity constraint. This model is implemented and tested with 97 genomes (120 replicons). The result was analyzed to show the usefulness of our model. Especially, analysis of gene clusters that belong to B. subtilis and E. coli demonstrated that our model predicted many experimentally verified operons and functionally related clusters. Our program is fast enough to provide a sevice on the web at http://platcom. informatics.indiana.edu/platcom/. Users can select any combination of 97 genomes to predict gene teams. PMID:16447961

  5. Trajectories in Close Proximity to Asteroids

    NASA Technical Reports Server (NTRS)

    Scheeres, D. J.

    2000-01-01

    Spacecraft motion in close proximity to irregularly shaped, rotating bodies such as asteroids presents a unique dynamical environment as compared to most space missions. There are several fundamental novelties in this environment that spacecraft must deal with. These include the possibility of orbital instabilities that can act over very short time spans (on the order of hours for some systems), possible non-uniform rotation of the central gravity field, divergence of traditional gravity field representations when close to the asteroid surface, dominance of perturbing forces, an extremely large asteroid model parameter space that must be prepared for in the absence of reliable information, and the possibility of employing new and novel trajectory control techniques such as hovering and repeated landings on the asteroid surface. An overview of how these novelties impact the space of feasible close proximity operations and how different asteroid model properties will affect their implementation is given. In so doing, four fundamental types of close proximity operations will be defined. Listed in order of increasing technical difficulty these are: (1) close, stable orbits; (2) low-altitude flyovers; (3) landing trajectories; and (4) hovering trajectories. The feasibility and difficulty of implementing these operations will vary as a function of the asteroid shape, size, density, and rotation properties, and as a function of the spacecraft navigation capability. Additional information is contained in the original extended abstract.

  6. Management of proximal humerus fractures in adults.

    PubMed

    Vachtsevanos, Leonidas; Hayden, Lydia; Desai, Aravind S; Dramis, Asterios

    2014-11-18

    The majority of proximal humerus fractures are low-energy osteoporotic injuries in the elderly and their incidence is increasing in the light of an ageing population. The diversity of fracture patterns encountered renders objective classification of prognostic value challenging. Non-operative management has been associated with good functional outcomes in stable, minimally displaced and certain types of displaced fractures. Absolute indications for surgery are infrequent and comprise compound, pathological, multi-fragmentary head-splitting fractures and fracture dislocations, as well as those associated with neurovascular injury. A constantly expanding range of reconstructive and replacement options however has been extending the indications for surgical management of complex proximal humerus fractures. As a result, management decisions are becoming increasingly complicated, in an attempt to provide the best possible treatment for each individual patient, that will successfully address their specific fracture configuration, comorbidities and functional expectations. Our aim was to review the management options available for the full range of proximal humerus fractures in adults, along with their specific advantages, disadvantages and outcomes. PMID:25405098

  7. Salicylate-induced proximal tubular dysfunction.

    PubMed

    Tsimihodimos, Vasilis; Psychogios, Nikolaos; Kakaidi, Varvara; Bairaktari, Eleni; Elisaf, Moses

    2007-09-01

    We describe the case of a 17-year-old girl who was admitted to our clinic for drug poisoning. Twelve hours after the ingestion of 25 tablets of aspirin (12.5 g of acetylsalicylic acid), the patient had a generalized proximal tubular dysfunction characterized by glucosuria (in the face of normal serum glucose levels), proteinuria, and uric acid wasting. Further characterization of the tubular dysfunction using high-resolution proton nuclear magnetic resonance spectroscopy of the urine showed a pattern consistent with proximal tubular injury. An important characteristic of the salicylate-induced proximal tubular dysfunction in our patient was its rapid reversibility. A trend toward normalization of fractional excretion values of electrolytes was observed 2 days after ingestion. Determination of serum and urine metabolites and spectroscopy of urine 15 days later showed no evidence of tubular dysfunction. The mechanisms potentially implicated in the pathogenesis of salicylate-induced Fanconi syndrome are discussed and a brief review of the relevant literature is provided. PMID:17720526

  8. Links between soil modelling and proximal sensing

    NASA Astrophysics Data System (ADS)

    Aitkenhead, Matt; McBratney, Alex; Minasny, Budiman

    2015-04-01

    Proximal sensing of soils can provide valuable information for soil modelling, by providing baseline data and validating model predictions through direct observation of soil characteristics. A wide range of soil parameters can be estimated using proximal sensing of soils (PSS), often simultaneously using single hand-held systems, of which there are many types. The benefits for soil modelling include direct observation of modelled parameters, rapid assessment in field conditions and digital data acquisition, making the transfer of information to soil models relatively straightforward. This is an active area of development, with research into improved methods of field-based capture of soil parameters directly relevant for soil modelling. A number of challenges exist, including the removal of or accounting for the effects of field conditions (e.g. soil moisture and structure), and the development of libraries of data that will allow calibration models to be produced. We present an overview of PSS as it relates to soil modelling, including equipment types, calibration approaches, cloud-based processing, soil parameters and processes estimated using PSS, and opportunities and challenges for the future. We also identify and discuss the possibilities for integration of modelling and proximal sensing within precision agriculture/precision land management.

  9. Autophagy Induces Prosenescent Changes in Proximal Tubular S3 Segments.

    PubMed

    Baisantry, Arpita; Bhayana, Sagar; Rong, Song; Ermeling, Esther; Wrede, Christoph; Hegermann, Jan; Pennekamp, Petra; Sörensen-Zender, Inga; Haller, Hermann; Melk, Anette; Schmitt, Roland

    2016-06-01

    Evidence suggests that autophagy promotes the development of cellular senescence. Because cellular senescence contributes to renal aging and promotes the progression from AKI to CKD, we investigated the potential effect of tubular autophagy on senescence induction. Compared with kidneys from control mice, kidneys from mice with conditional deletion of autophagy-related 5 (Atg5) for selective ablation of autophagy in proximal tubular S3 segments (Atg5(Δ) (flox/) (Δ) (flox)) presented with significantly less tubular senescence, reduced interstitial fibrosis, and superior renal function 30 days after ischemia/reperfusion injury. To correlate this long-term outcome with differences in the early injury process, kidneys were analyzed 2 hours and 3 days after reperfusion. Notably, compared with kidneys of control mice, Atg5(Δ) (flox/) (Δ) (flox) kidneys showed more cell death in outer medullary S3 segments at 2 hours but less tubular damage and inflammation at day 3. These data suggest that the lack of autophagy prevents early survival mechanisms in severely damaged tubular cells. However, if such compromised cells persist, then they may lead to maladaptive repair and proinflammatory changes, thereby facilitating the development of a senescent phenotype and CKD. PMID:26487561

  10. 14 CFR 135.153 - Ground proximity warning system.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Ground proximity warning system. 135.153... Equipment § 135.153 Ground proximity warning system. (a) No person may operate a turbine-powered airplane... equipped with an approved ground proximity warning system. (b) (c) For a system required by this...

  11. 14 CFR 135.153 - Ground proximity warning system.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Ground proximity warning system. 135.153... Equipment § 135.153 Ground proximity warning system. (a) No person may operate a turbine-powered airplane... equipped with an approved ground proximity warning system. (b) (c) For a system required by this...

  12. Scintillation proximity assay using polymeric membranes

    SciTech Connect

    Mansfield, R.K.

    1992-01-01

    Liquid scintillation counting (LSC) is typically used to quantify electron emitting isotopes. In LSC, radioactive samples are dissolved in an organic fluor solution (scintillation cocktail) to ensure that the label is close enough to the fluor molecules to be detected. Although efficient, scintillation cocktail is neither specific or selective for samples labeled with the same radioisotope. Scintillation cocktail is flammable posing significant health risks to the user and is expensive to purchase and discard. Scintillation Proximity Assay (SPA) is a radioanalytical technique where only those radiochemical entities (RCE's) bound to fluor containing matrices are detected. Only bound RCE's are in close enough proximity the entrapped fluor molecules to induce scintillations. Unbound radioligands are too far removed from the fluor molecules to be detected. The research in this dissertation focused on the development and evaluation of fluor-containing membranes (scintillation proximity membranes, SP membranes) to be used for specific radioanalytical techniques without using scintillation cocktail. Polysulfone and PVC SP membranes prepared in our laboratory were investigated for radioimmunossay (RIA) where only bound radioligand is detected, thereby eliminating the separation step impeding the automation of RIA. These SP membranes performed RIA where the results were nearly identical to commercial SP microbeads. SP membranes functionalized with quaternary ammonium hydroxide moieties were able to trap and quantify [sup 14]CO[sub 2] without using liquid scintillation cocktail. RCE's bound in the pore structure of SP membranes are intimate with the entrapped fluor providing the geometry needed for high detection efficiencies. Absorbent SP membranes were used in radiation surveys and were shown to be as effective as conventional survey techniques using filter paper and scintillation cocktail.

  13. Delayed homicides and the proximate cause.

    PubMed

    Lin, Peter; Gill, James R

    2009-12-01

    Delayed homicides result from complications of remote injuries inflicted by "the hands of another." The investigation of delayed homicides may be a challenge due to a number of factors including: failure to report the death to the proper authorities, lack of ready and adequate documentation of the original injury and circumstances, and jurisdictional differences between the places of injury and death. The certification of these deaths also requires the demonstration of a pathophysiologic link between the remote injury and death. In sorting through these issues, it is helpful to rely upon the definition of the proximate cause of death. Over a 2-year period in New York City, there were 1211 deaths certified as homicide of which 42 were due to injuries sustained greater than 1 year before death. The survival interval ranged from 1.3 to 43.2 years. The most common immediate causes of death were: infections (22), seizures (7), and intestinal obstructions/hernias (6). Common patterns of complications included infection following a gunshot wound of the spinal cord, seizure disorder due to blunt head trauma, and intestinal obstruction/hernia due to adhesions from an abdominal stab wound. Spinal cord injuries resulted in paraplegia in 14 instances and quadriplegia in 8. The mean survival interval for paraplegics was 20.3 years and 14.8 years for quadriplegics; infections were a frequent immediate cause of death in both groups, particularly infections due to chronic bladder catheterization. The definition of proximate cause originated with civil law cases and was later applied to death certification as the proximate cause of death. The gradual extinction of the "year and a day rule" for the limitation of bringing homicide charges in delayed deaths may result in more of these deaths going to trial. Medical examiners/coroners must be able to explain the reasoning behind these death certifications and maintain consistent standards for the certification of all delayed deaths due

  14. Hand Replantation with Proximal Row Carpectomy

    PubMed Central

    Lee, Young-Keun; Lee, Hang-Ho; Park, Ji-Kang; Kim, Joo-Yong; Dhawan, Vikas

    2008-01-01

    The purpose of this study is to present our operative technique and postoperative results of the hand replantation with proximal row carpectomy in cases of complete amputation at the level of wrist joint. From May 2003 to April 2005, five patients suffered from complete amputation of the hand due to industrial trauma. Amputation level was radiocarpal joint in three cases and midcarpal joint in two cases. Three cases represented guillotine type and two cases with local crush type injuries. All were men and the mean age was 26.6 years. The mean follow-up period was 26.8 months. At the time of replantation, the wrist joint was stabilized with transarticular fixation using three to four Kirschner’s wires after performing proximal row carpectomy. Postoperatively, functional results such as muscle strength, range of motion of the wrist and fingers, and sensory recovery were assessed according to Chen’s criteria. Joint width and arthritic changes of the radio-capitate joint were evaluated with radiologic tools. According to Chen’s criteria, the overall results in five cases were classified as grade II. Intrinsic muscle power of hands was found to be grade 4. The mean grip and pinch powers were 41% and 45%, respectively, compared to contralateral hand. The mean arc of flexion–extension of wrist was 53°. Total mean active motion of fingers was 215 degrees. Static two-point discrimination of fingertip ranged from 8 to 13 mm. On the follow-up, computerized tomography showed well-preserved radio-capitate joint space without any arthritic changes. While performing hand replantation after amputation at the radiocarpal or midcarpal level, proximal row carpectomy is a useful procedure to preserve joint motion of the wrist in selected cases. PMID:18855073

  15. Bicarbonate secretion by rabbit proximal colon.

    PubMed

    Sullivan, S K; Smith, P L

    1986-10-01

    Stripped segments of proximal colon (1-6 cm distal to the ampulla caecalis coli) were studied in vitro in Ussing chambers under short-circuit conditions using the pH-stat technique. With glucose and HCO3-CO2 present in the serosal bathing solution only, proximal colon alkalinizes the luminal bathing solution at a rate of 2.1 +/- 0.2 mu eq X h-1 X cm-2 (n = 36). With HCO3-CO2 present in the luminal bathing solution alone, proximal colon does not significantly acidify or alkalinize the serosal bathing solution. Addition of glucose (10 mM) to the luminal bathing solution abolished luminal alkalinization. Removal of HCO3 and CO2 from the serosal bathing solution or replacement of O2 with N2 also abolished luminal alkalinization. Acetazolamide (0.1 mM) added to both bathing solutions did not alter the rate of luminal alkalinization. Ion-replacement studies revealed that the alkalinization process was highly dependent on the presence of Na in the bathing solutions and much less dependent on the presence of Cl. Furthermore, ouabain (0.1 mM) significantly reduced luminal alkalinization. As in rabbit ileum, serosal epinephrine (0.1 mM) did not alter luminal alkalinization but increased serosal alkalinization by a Na-dependent mechanism. These results suggest that luminal alkalinization results from a Na-dependent, active transcellular HCO3 transport process and that a Na-dependent HCO3 absorptive process is activated by adrenergic stimuli. PMID:3766731

  16. Giant proximity effect in cuprate superconductors.

    PubMed

    Bozovic, I; Logvenov, G; Verhoeven, M A J; Caputo, P; Goldobin, E; Beasley, M R

    2004-10-01

    Using an advanced molecular beam epitaxy system, we have reproducibly synthesized atomically smooth films of high-temperature superconductors and uniform trilayer junctions with virtually perfect interfaces. We found that supercurrent runs through very thick barriers. We can rule out pinholes and microshorts; this "giant proximity effect" (GPE) is intrinsic. It defies the conventional explanation; it might originate in resonant tunneling through pair states in an almost-superconducting barrier. GPE may also be significant for superconducting electronics, since thick barriers are easier to fabricate. PMID:15524925

  17. Impacted valgus fractures of the proximal humerus.

    PubMed

    Ribeiro, Fabiano Rebouças; Takesian, Fernando Hovaguim; Bezerra, Luiz Eduardo Pimentel; Filho, Rômulo Brasil; Júnior, Antonio Carlos Tenor; da Costa, Miguel Pereira

    2016-01-01

    Impacted valgus fractures of the proximal humerus are considered to be a special type fracture, since impaction of the humeral head on the metaphysis with maintenance of the posteromedial periosteum improves the prognosis regarding occurrences of avascular necrosis. This characteristic can also facilitate the reduction maneuver and increase the consolidation rate of these fractures, even in more complex cases. The studies included were obtained by searching the Bireme, Medline, PubMed, Cochrane Library and Google Scholar databases for those published between 1991 and 2013. The objective of this study was to identify the most common definitions, classifications and treatment methods used for these fractures in the orthopedic medical literature. PMID:27069878

  18. Space station proximity operations and window design

    NASA Technical Reports Server (NTRS)

    Haines, Richard F.

    1988-01-01

    On-orbit proximity operations (PROX-OPS) consist of all extravehicular activity (EVA) within 1 km of the space station. Because of the potentially large variety of PROX-OPS, very careful planning for space station windows is called for and must consider a great many human factors. The following topics are discussed: (1) basic window design philosophy and assumptions; (2) the concept of the local horizontal - local vertical on-orbit; (3) window linear dimensions; (4) selected anthropomorphic considerations; (5) displays and controls relative to windows; and (6) full window assembly replacement.

  19. Unilateral Isolated Proximal Femoral Focal Deficiency

    PubMed Central

    Doğer, Emek; Köpük, Şule Y.; Çakıroğlu, Yiğit; Çakır, Özgür; Yücesoy, Gülseren

    2013-01-01

    Objective. To discuss a patient with a prenatal diagnosis of unilateral isolated femoral focal deficiency. Case. Antenatal diagnosis of unilateral isolated femoral focal deficiency was made at 20 weeks of gestation. The length of left femur was shorter than the right, and fetal femur length was below the fifth percentile. Proximal femoral focal deficiency was diagnosed. After delivery, the diagnosis was confirmed with skeletal radiographs and magnetic resonance imaging. In prenatal ultrasonographic examination, the early recognition and exclusion of skeletal dysplasias is important; moreover, treatment plans should be initiated, and valuable information should be provided to the family. PMID:23984135

  20. Metastatic disease of the proximal femur.

    PubMed

    Faisham, W I; Zulmi, W; Biswal, B M

    2003-03-01

    Since January 1999, ten patients had undergone surgical treatment for metastatic bony lesions of proximal femur at this centre. Seven of these patients were treated for complete pathological fractures, one for impending fracture and one for revision of internal fixation and loosening of hemiarthroplasty. Primary malignancies were located in breast in four cases, prostate in three and one in lung, thyroid and neurofibrosarcoma. Two patients had died within six months after surgery, four after 1 year while the remaining four were still alive. The mean duration of survival was eleven months. Nine patients had been ambulating pain free and there were no failure of reconstruction. PMID:14556337

  1. An automated system for spacecraft proximity operations

    NASA Technical Reports Server (NTRS)

    Bergmann, E.

    1991-01-01

    With the advent of multiple-vehicle operations in support of the space station, on-orbit refurbishment, and several other missions, there is a need to intelligently plan proximity operations trajectories that will conserve limited available fuel while avoiding collisions. Upon reaching the objective, the capture process entails several unique considerations, such as coordinating motion with a tumbling target, the capture itself, and adapting to control of the new configuration resulting from the capture operation. This paper outlines a systematic process of technical development over several years at the Draper laboratory, culminating in a capability to perform manual augmented or fully autonomous rendezvous, capture, and control of the resulting configuration.

  2. Ganglions of the proximal interphalangeal joint.

    PubMed

    Cheng, C A; Rockwell, W B

    1999-08-01

    Ganglion cysts-the most common hand tumors-usually affect women in their twenties and thirties. The cause of these cysts is unknown, although trauma has been postulated as an inciting factor. Ganglions occur most commonly at the dorsal and palmar wrist. However, ganglions of the proximal interphalangeal (PIP) joint are rare. Four patients with PIP joint ganglions were recently treated at our institution. Three received aspiration and one received operative therapy, all with good results. All four patients were older than 65 years. PMID:10470671

  3. Impacted valgus fractures of the proximal humerus☆

    PubMed Central

    Ribeiro, Fabiano Rebouças; Takesian, Fernando Hovaguim; Bezerra, Luiz Eduardo Pimentel; Filho, Rômulo Brasil; Júnior, Antonio Carlos Tenor; da Costa, Miguel Pereira

    2016-01-01

    Impacted valgus fractures of the proximal humerus are considered to be a special type fracture, since impaction of the humeral head on the metaphysis with maintenance of the posteromedial periosteum improves the prognosis regarding occurrences of avascular necrosis. This characteristic can also facilitate the reduction maneuver and increase the consolidation rate of these fractures, even in more complex cases. The studies included were obtained by searching the Bireme, Medline, PubMed, Cochrane Library and Google Scholar databases for those published between 1991 and 2013. The objective of this study was to identify the most common definitions, classifications and treatment methods used for these fractures in the orthopedic medical literature. PMID:27069878

  4. Recent Updates on the Proximal Tubule Renin-Angiotensin System in Angiotensin II-Dependent Hypertension.

    PubMed

    Li, Xiao C; Zhuo, Jia L

    2016-08-01

    It is well recognized that the renin-angiotensin system (RAS) exists not only as circulating, paracrine (cell to cell), but also intracrine (intracellular) system. In the kidney, however, it is difficult to dissect the respective contributions of circulating RAS versus intrarenal RAS to the physiological regulation of proximal tubular Na(+) reabsorption and hypertension. Here, we review recent studies to provide an update in this research field with a focus on the proximal tubular RAS in angiotensin II (ANG II)-induced hypertension. Careful analysis of available evidence supports the hypothesis that both local synthesis or formation and AT1 (AT1a) receptor- and/or megalin-mediated uptake of angiotensinogen (AGT), ANG I and ANG II contribute to high levels of ANG II in the proximal tubules of the kidney. Under physiological conditions, nearly all major components of the RAS including AGT, prorenin, renin, ANG I, and ANG II would be filtered by the glomerulus and taken up by the proximal tubules. In ANG II-dependent hypertension, the expression of AGT, prorenin, and (pro)renin receptors, and angiotensin-converting enzyme (ACE) is upregulated rather than downregulated in the kidney. Furthermore, hypertension damages the glomerular filtration barrier, which augments the filtration of circulating AGT, prorenin, renin, ANG I, and ANG II and their uptake in the proximal tubules. Together, increased local ANG II formation and augmented uptake of circulating ANG II in the proximal tubules, via activation of AT1 (AT1a) receptors and Na(+)/H(+) exchanger 3, may provide a powerful feedforward mechanism for promoting Na(+) retention and the development of ANG II-induced hypertension. PMID:27372447

  5. Proximate determinants of fertility in peninsular Malaysia.

    PubMed

    Tey, Nai Peng; Ng, Sor Tho; Yew, Siew Yong

    2012-05-01

    The continuing decline in fertility despite a contraction in contraceptive use in Peninsular Malaysia since the mid-1980s has triggered considerable interest in the reasons behind this phenomenon, such as increase in abortion, sterility, and out-of-wedlock pregnancy. Fertility decline has been attributed to rapid socioeconomic development, which can only influence fertility through the intermediate variables. Application of vital statistics, population census, and survey data of Peninsular Malaysia on Bongaarts's model vindicates that marriage postponement and contraceptive use are the 2 most important proximate determinants of fertility, but the effects are not uniform across the ethnic groups. For instance, the predicted total fertility rate for Chinese and Malays are 2.9 and 1.6, respectively, compared with the observed level of 3.0 and 1.9. Postpartum infecundability and abortion also play a part in explaining ethnic fertility differentials. The fertility inhibiting effects of these proximate determinants have significant implications on reproductive health and future population growth. PMID:21490114

  6. Synostosis of the proximal tibiofibular joint.

    PubMed

    Sferopoulos, Nikolaos K

    2010-01-01

    The incidence of synostosis of the proximal tibiofibular joint (TFJ) was assessed among 1029 patients examined for osteoarthritis of the knee in a 4-year period. Radiographic evidence of a synostosis of the proximal TFJ was demonstrated in 3 knees (3 patients). The synostosis appeared incidental and was not the cause of symptoms in any of them. These patients were further examined with MRI and/or CT scans. In two cases, which were found to be primary (idiopathic), the synostosis was complete and bony. In a third case the lesion was secondary (acquired) to surgical reconstruction for a depressed fracture of the lateral tibial plateau. This iatrogenic complication followed open reduction, internal fixation, and grafting with synthetic bone. The bridging of the joint on the CT views was partial and compatible with ectopic calcification rather than ossification. The patients were treated conservatively and were followed for an average period of 3 years. No evidence that the synostosis accelerated the onset or progression of the degenerative changes to the ipsilateral knee could be verified. PMID:20592991

  7. Synostosis of the Proximal Tibiofibular Joint

    PubMed Central

    Sferopoulos, Nikolaos K.

    2010-01-01

    The incidence of synostosis of the proximal tibiofibular joint (TFJ) was assessed among 1029 patients examined for osteoarthritis of the knee in a 4-year period. Radiographic evidence of a synostosis of the proximal TFJ was demonstrated in 3 knees (3 patients). The synostosis appeared incidental and was not the cause of symptoms in any of them. These patients were further examined with MRI and/or CT scans. In two cases, which were found to be primary (idiopathic), the synostosis was complete and bony. In a third case the lesion was secondary (acquired) to surgical reconstruction for a depressed fracture of the lateral tibial plateau. This iatrogenic complication followed open reduction, internal fixation, and grafting with synthetic bone. The bridging of the joint on the CT views was partial and compatible with ectopic calcification rather than ossification. The patients were treated conservatively and were followed for an average period of 3 years. No evidence that the synostosis accelerated the onset or progression of the degenerative changes to the ipsilateral knee could be verified. PMID:20592991

  8. True Aneurysm of the Proximal Brachial Artery

    PubMed Central

    Ramakrishna, Pinjala; Mahapatra, Sandeep; Rajesh, Ratna

    2013-01-01

    A 35-year-old farmer presented with complaints of pain in the right upper limb for 1 month and bluish discoloration of the right-hand finger tips with tingling and numbness. He sustained injury to the right upper limb while lifting a heavy object 1 mo previously. There was an ovoid swelling of 4 × 2 cm on the medial aspect of the right arm, 12 cm above the medial epicondyle at the level of the armpit with visible pulsations. There was distal neurovascular deficit. Duplex scan of the right upper limb arterial system revealed a pseudoaneurysm of the proximal right brachial artery, with dampened monophasic flow in the ulnar artery and no flow in the radial artery. Spiral computed tomography angiogram showed the presence of an echogenic periarterial lesion in the proximal brachial artery suggestive of pseudoaneurysm or an extrinsic compression by hematoma. Distal brachial artery was found to have filled with thrombus, with non-opacification of the radial and the distal ulnar artery. The patient was posted for excision of the aneurysmal arterial segment. A 5-cm-long reversed segment of vein graft was interposed in between the cut ends of the brachial artery. Histopathology: Specimen shows a part of the vessel wall composed of intimal, medial, and adventitial layers with intraluminal thrombus showing evidence of recanalization suggestive of true aneurysm of the brachial artery. PMID:26798692

  9. Rheogenic transport in the renal proximal tubule

    PubMed Central

    1983-01-01

    The electrophysiology of the renal Na-K ATPase was studied in isolated perfused amphibian proximal tubules during alterations in bath (serosal) potassium. Intracellular and extracellular ionic activity measurements permitted continuous evaluation of the Nernst potentials for Na+, K+, and Cl- across the basolateral membrane. The cell membrane and transepithelial potential differences and resistances were also determined. Return of K to the basal (serosal) solution after a 20-min incubation in K-free solution hyperpolarized the basolateral membrane to an electrical potential that was more negative than the Nernst potential for either Na, Cl, or K. This constitutes strong evidence that at least under stimulated conditions the Na-K ATPase located at the basolateral membrane of the renal proximal tubule mediates a rheogenic process which directly transfers net charge across the cell membrane. Interpretation of these data in terms of an electrical equivalent circuit permitted calculation of both the rheogenic current and the Na/K coupling ratio of the basolateral pump. During the period between 1 and 3 min after pump reactivation by return of bath K, the basolateral rheogenic current was directly proportional to the intracellular Na activity, and the pump stoichiometry transiently exceeded the coupling ratio of 3Na to 2K reported in other preparations. PMID:6319539

  10. Demonstration of automated proximity and docking technology

    NASA Technical Reports Server (NTRS)

    Anderson, Robert L.; Tsugawa, Roy K.; Bryan, Thomas C.

    1991-01-01

    Automated spacecraft docking operations are being performed using a full scale motion based simulator and an optical sensor. This presentation will discuss the work in progress at TRW and MSFC facilities to study the problem of automated proximity and docking operations. The docking sensor used in the MSFC Optical Sensor and simulation runs are performed using the MSFC Flat Floor Facility. The control algorithms and six degrees of freedom (6DOF) simulation software were developed at TRW and integrated into the MSFC facility. Key issues being studied are the quantification of docking sensor requirements and operational constraints necessary to perform automated docking maneuvers, control algorithms capable of performing automated docking in the presence of sensitive and noisy sensor data, and sensor technologies for automated proximity and docking operations. As part of this study the MSFC sensor characteristics were analyzed and modeled so that off line simulation runs can be performed for control algorithm testing. Our goal is to develop and demonstrate full 6DOF docking capabilities with actual sensors on the MSFC motion based simulator. We present findings from actual docking simulation runs which show sensor and control loop performance as well as problem areas which require close attention. The evolution of various control algorithms using both phase plane and Clohessy-Wiltshire techniques are discussed. In addition, 6DOF target acquisition and control strategies are described.

  11. An improved proximity force approximation for electrostatics

    SciTech Connect

    Fosco, Cesar D.; Lombardo, Fernando C.; Mazzitelli, Francisco D.

    2012-08-15

    A quite straightforward approximation for the electrostatic interaction between two perfectly conducting surfaces suggests itself when the distance between them is much smaller than the characteristic lengths associated with their shapes. Indeed, in the so called 'proximity force approximation' the electrostatic force is evaluated by first dividing each surface into a set of small flat patches, and then adding up the forces due two opposite pairs, the contributions of which are approximated as due to pairs of parallel planes. This approximation has been widely and successfully applied in different contexts, ranging from nuclear physics to Casimir effect calculations. We present here an improvement on this approximation, based on a derivative expansion for the electrostatic energy contained between the surfaces. The results obtained could be useful for discussing the geometric dependence of the electrostatic force, and also as a convenient benchmark for numerical analyses of the tip-sample electrostatic interaction in atomic force microscopes. - Highlights: Black-Right-Pointing-Pointer The proximity force approximation (PFA) has been widely used in different areas. Black-Right-Pointing-Pointer The PFA can be improved using a derivative expansion in the shape of the surfaces. Black-Right-Pointing-Pointer We use the improved PFA to compute electrostatic forces between conductors. Black-Right-Pointing-Pointer The results can be used as an analytic benchmark for numerical calculations in AFM. Black-Right-Pointing-Pointer Insight is provided for people who use the PFA to compute nuclear and Casimir forces.

  12. Severity and Frequency of Proximal Tubule Injury Determines Renal Prognosis.

    PubMed

    Takaori, Koji; Nakamura, Jin; Yamamoto, Shinya; Nakata, Hirosuke; Sato, Yuki; Takase, Masayuki; Nameta, Masaaki; Yamamoto, Tadashi; Economides, Aris N; Kohno, Kenji; Haga, Hironori; Sharma, Kumar; Yanagita, Motoko

    2016-08-01

    AKI increases the risk of developing CKD, but the mechanisms linking AKI to CKD remain unclear. Because proximal tubule injury is the mainstay of AKI, we postulated that proximal tubule injury triggers features of CKD. We generated a novel mouse model to induce proximal tubule-specific adjustable injury by inducing the expression of diphtheria toxin (DT) receptor with variable prevalence in proximal tubules. Administration of high-dose DT in mice expressing the DT receptor consistently caused severe proximal tubule-specific injury associated with interstitial fibrosis and reduction of erythropoietin production. Mild proximal tubule injury from a single injection of low-dose DT triggered reversible fibrosis, whereas repeated mild injuries caused sustained interstitial fibrosis, inflammation, glomerulosclerosis, and atubular glomeruli. DT-induced proximal tubule-specific injury also triggered distal tubule injury. Furthermore, injured tubular cells cocultured with fibroblasts stimulated induction of extracellular matrix and inflammatory genes. These results support the existence of proximal-distal tubule crosstalk and crosstalk between tubular cells and fibroblasts. Overall, our data provide evidence that proximal tubule injury triggers several features of CKD and that the severity and frequency of proximal tubule injury determines the progression to CKD. PMID:26701981

  13. Optical detection of the superconducting proximity effect

    SciTech Connect

    Greene, L.H.; Abeyta, A.C.; Roshchin, I.V.; Robinson, I.K.; Dorsten, J.F.; Tanzer, T.A.; Bohn, P.W.

    1996-12-31

    The authors present the first detection of a superconducting proximity effect by optical techniques. Raman scattering on n{sup +}-InAs is performed through very thin, high-quality, superconducting Nb films grown directly on the (100) InAs surface. The 6 to 10 nm thick Nb films exhibit {Tc}`s of 2.5 to 5.5 K, as measured by electronic transport, and are flat to {approximately}0.5 nm, as measured by x-ray reflectivity. As the Nb/InAs structure is cooled below the superconducting transition temperature, the magnitude of the unscreened LO phonon mode, associated with the surface charge accumulation layer in the InAs, is observed to be enhanced by more than 40%. This reversible change is observed only when the Nb is in good electrical contact with the InAs.

  14. Parallel Proximity Detection for Computer Simulation

    NASA Technical Reports Server (NTRS)

    Steinman, Jeffrey S. (Inventor); Wieland, Frederick P. (Inventor)

    1997-01-01

    The present invention discloses a system for performing proximity detection in computer simulations on parallel processing architectures utilizing a distribution list which includes movers and sensor coverages which check in and out of grids. Each mover maintains a list of sensors that detect the mover's motion as the mover and sensor coverages check in and out of the grids. Fuzzy grids are includes by fuzzy resolution parameters to allow movers and sensor coverages to check in and out of grids without computing exact grid crossings. The movers check in and out of grids while moving sensors periodically inform the grids of their coverage. In addition, a lookahead function is also included for providing a generalized capability without making any limiting assumptions about the particular application to which it is applied. The lookahead function is initiated so that risk-free synchronization strategies never roll back grid events. The lookahead function adds fixed delays as events are scheduled for objects on other nodes.

  15. [Ophthalmologists in the proximity of Adolf Hitler].

    PubMed

    Rohrbach, J M

    2012-10-01

    Adolf Hitler met or at least knew about 5 ophthalmologists. The chair of ophthalmology in Berlin, Walther Löhlein, personally examined Hitler's eyes at least two times. The chair of ophthalmology in Breslau, Walter Dieter, developed "air raid protection spectacles" with the aid of high representatives of the NS-system and probably Adolf Hitler himself. Heinrich Wilhelm Kranz became rector of the universities of Giessen and Frankfurt/Main. He was known as a very strict advocate of the NS-race hygiene. Werner Zabel made plans for Hitler's diet and tried to interfere with Hitler's medical treatment. Finally, Hellmuth Unger was an influential representative of the medical press and a famous writer. Three of his novels with medical topics were made into a film which Hitler probably saw. Hitler had, so to say, a small "ophthalmological proximity" which, however, did not play a significant role for himself or the NS-state. PMID:22664943

  16. Parallel Proximity Detection for Computer Simulations

    NASA Technical Reports Server (NTRS)

    Steinman, Jeffrey S. (Inventor); Wieland, Frederick P. (Inventor)

    1998-01-01

    The present invention discloses a system for performing proximity detection in computer simulations on parallel processing architectures utilizing a distribution list which includes movers and sensor coverages which check in and out of grids. Each mover maintains a list of sensors that detect the mover's motion as the mover and sensor coverages check in and out of the grids. Fuzzy grids are included by fuzzy resolution parameters to allow movers and sensor coverages to check in and out of grids without computing exact grid crossings. The movers check in and out of grids while moving sensors periodically inform the grids of their coverage. In addition, a lookahead function is also included for providing a generalized capability without making any limiting assumptions about the particular application to which it is applied. The lookahead function is initiated so that risk-free synchronization strategies never roll back grid events. The lookahead function adds fixed delays as events are scheduled for objects on other nodes.

  17. Protein structure alignment beyond spatial proximity

    PubMed Central

    Wang, Sheng; Ma, Jianzhu; Peng, Jian; Xu, Jinbo

    2013-01-01

    Protein structure alignment is a fundamental problem in computational structure biology. Many programs have been developed for automatic protein structure alignment, but most of them align two protein structures purely based upon geometric similarity without considering evolutionary and functional relationship. As such, these programs may generate structure alignments which are not very biologically meaningful from the evolutionary perspective. This paper presents a novel method DeepAlign for automatic pairwise protein structure alignment. DeepAlign aligns two protein structures using not only spatial proximity of equivalent residues (after rigid-body superposition), but also evolutionary relationship and hydrogen-bonding similarity. Experimental results show that DeepAlign can generate structure alignments much more consistent with manually-curated alignments than other automatic tools especially when proteins under consideration are remote homologs. These results imply that in addition to geometric similarity, evolutionary information and hydrogen-bonding similarity are essential to aligning two protein structures. PMID:23486213

  18. Vaccination Rates are Associated With Functional Proximity But Not Base Proximity of Vaccination Clinics

    PubMed Central

    Beshears, John; Choi, James J.; Laibson, David I.; Madrian, Brigitte C.

    2016-01-01

    Background: Routine annual influenza vaccinations are recommended for persons 6 months of age and older, but less than half of US adults get vaccinated. Many employers offer employees free influenza vaccinations at workplace clinics, but even then take-up is low. Objective: To determine whether employees are significantly more likely to get vaccinated if they have a higher probability of walking by the clinic for reasons other than vaccination. Method: We obtained data from an employer with a free workplace influenza vaccination clinic. Using each employee’s building entry/exit swipe card data, we test whether functional proximity—the likelihood that the employee walks by the clinic for reasons other than vaccination—predicts whether the employee gets vaccinated at the clinic. We also test whether base proximity—the inverse of walking distance from the employee’s desk to the clinic—predicts vaccination probability. Participants: A total of 1801 employees of a health benefits administrator that held a free workplace influenza vaccination clinic. Results: A 2 SD increase in functional proximity is associated with a 6.4 percentage point increase in the probability of vaccination (total vaccination rate at company=40%), even though the average employee’s desk is only 166 meters from the clinic. Base proximity does not predict vaccination probability. Conclusions and Relevance: Minor changes in the environment can have substantial effects on the probability of vaccination. If these results generalize, health systems should emphasize functional proximity over base proximity when locating preventive health services. PMID:27177295

  19. Proximity Operations and Docking Sensor Development

    NASA Technical Reports Server (NTRS)

    Howard, Richard T.; Bryan, Thomas C.; Brewster, Linda L.; Lee, James E.

    2009-01-01

    The Next Generation Advanced Video Guidance Sensor (NGAVGS) has been under development for the last three years as a long-range proximity operations and docking sensor for use in an Automated Rendezvous and Docking (AR&D) system. The first autonomous rendezvous and docking in the history of the U.S. Space Program was successfully accomplished by Orbital Express, using the Advanced Video Guidance Sensor (AVGS) as the primary docking sensor. That flight proved that the United States now has a mature and flight proven sensor technology for supporting Crew Exploration Vehicles (CEV) and Commercial Orbital Transport Systems (COTS) Automated Rendezvous and Docking (AR&D). NASA video sensors have worked well in the past: the AVGS used on the Demonstration of Autonomous Rendezvous Technology (DART) mission operated successfully in spot mode out to 2 km, and the first generation rendezvous and docking sensor, the Video Guidance Sensor (VGS), was developed and successfully flown on Space Shuttle flights in 1997 and 1998. 12 Parts obsolescence issues prevent the construction of more AVGS units, and the next generation sensor was updated to allow it to support the CEV and COTS programs. The flight proven AR&D sensor has been redesigned to update parts and add additional capabilities for CEV and COTS with the development of the Next Generation AVGS at the Marshall Space Flight Center. The obsolete imager and processor are being replaced with new radiation tolerant parts. In addition, new capabilities include greater sensor range, auto ranging capability, and real-time video output. This paper presents some sensor hardware trades, use of highly integrated laser components, and addresses the needs of future vehicles that may rendezvous and dock with the International Space Station (ISS) and other Constellation vehicles. It also discusses approaches for upgrading AVGS to address parts obsolescence, and concepts for minimizing the sensor footprint, weight, and power requirements

  20. Proximity induced Superconductivity in Epitaxial Graphene

    NASA Astrophysics Data System (ADS)

    Natterer, Fabian D.; Ha, Jeonghoon; Baek, Hongwoo; Zhang, Duming; Cullen, William; Zhitenev, Nikolai B.; Kuk, Young; Stroscio, Joseph A.

    The intimate electrical contact of a superconductor with a normal metal leads to an exchange of carriers through their boundary. Cooper pairs leak into the normal metal via Andreev reflection and enable the normal metal to acquire superconducting-like properties. The electron-hole conversion process in graphene is prominent due to relativistic quantum mechanics governing low energy chiral carriers in a multi-valley system. In the present experiment, we reveal spatial measurements of the proximity effect in graphene from a graphene-superconductor interface. Superconducting aluminum films were grown on epitaxial graphene on SiC. The aluminum films were discontinuous with networks of trenches in the film morphology reaching down to the substrate to exposed graphene terraces. Scanning tunneling spectra measured on the graphene terraces show a clear decay of the superconducting gap width with increasing separation from the graphene-aluminum edges. The decay length for the superconducting energy gap extends beyond 400 nm. Subtle deviations in the exponentially decaying energy gap were also observed on a much smaller length scale of tens of nanometers. Funding from SNSF (project 158468), NIST/CNST Grant 70NANB10H193, and KRF-2010-00349.

  1. Proximity operations considerations affecting spacecraft design

    NASA Astrophysics Data System (ADS)

    Staas, Steven K.

    Proximity operations can be defined as the maneuvering of two or more spacecraft within 1 nautical mile range, with relative velocity less than 10 feet per second. The passive vehicle is nontranslating and should provide for maintenance of the desired approach attitude. It must accommodate the active (translating) vehicle induced structural loads and performance characteristics (mating hardware tolerances), and support sensor compatibility (transponder, visual targets, etc.). The active vehicle must provide adequate sensor systems (relative state information, field-of-view, redundancy), flight control hardware (thruster sizing, minimal cross-coupling, performance margins, redundancy) and software (reconfigurable, attitude/rate modes, translation and rotation fine control authority) characteristic, and adequate non-propulsive consumables such as power. Operational concerns must be considered. These include the following: (1) the desired approach trajectory and relative orientation; (2) the active vehicle thruster plume effects (forces, torques, contamination) on the passive vehicle; and (3) procedures for contingencies such as loss of communications, sensor or propulsion failures, and target vehicle loss of control.

  2. Proximal spinal muscular atrophy: current orthopedic perspective

    PubMed Central

    Haaker, Gerrit; Fujak, Albert

    2013-01-01

    Spinal muscular atrophy (SMA) is a hereditary neuromuscular disease of lower motor neurons that is caused by a defective “survival motor neuron” (SMN) protein that is mainly associated with proximal progressive muscle weakness and atrophy. Although SMA involves a wide range of disease severity and a high mortality and morbidity rate, recent advances in multidisciplinary supportive care have enhanced quality of life and life expectancy. Active research for possible treatment options has become possible since the disease-causing gene defect was identified in 1995. Nevertheless, a causal therapy is not available at present, and therapeutic management of SMA remains challenging; the prolonged survival is increasing, especially orthopedic, respiratory and nutritive problems. This review focuses on orthopedic management of the disease, with discussion of key aspects that include scoliosis, muscular contractures, hip joint disorders, fractures, technical devices, and a comparative approach of conservative and surgical treatment. Also emphasized are associated complications including respiratory involvement, perioperative care and anesthesia, nutrition problems, and rehabilitation. The SMA disease course can be greatly improved with adequate therapy with established orthopedic procedures in a multidisciplinary therapeutic approach. PMID:24399883

  3. Proximal relationships between PTSD and drinking behavior.

    PubMed

    Kaysen, Debra; Stappenbeck, Cynthia; Rhew, Issac; Simpson, Tracy

    2014-01-01

    Co-morbid PTSD and alcohol use disorders are both common and debilitating. However, many of these studies rely on cross-sectional studies that obscure more complex relationships between PTSD and drinking. Event-level studies allow for examination of proximal relationships between PTSD and drinking. Among women (n=136 with past sexual victimization, n=40 no past trauma history), a two-part mixed hurdle model was used to examine daily PTSD and drinking. On days women experienced more intrusive and behavioral avoidance symptoms, they were more likely to drink. For a 2 SD increase in symptoms, there was a 5% increased likelihood of drinking, and for a 2 SD increase in dysphoric symptoms or negative affect, women drank approximately half drink less. Daily-level coping self-efficacy moderated the association between distress and drinking (IRR=0.91, p<0.01). Women who reported less coping drank more as their distress increased on a certain day whereas women who reported more coping drank about the same regardless of distress. Overall, findings suggest that specific PTSD symptoms are associated with higher alcohol use and that these relationships are moderated by daily coping self-efficacy. Implications of these findings for informing models of PTSD/AUD comorbidity, as well as clinical implications will be discussed. PMID:25511723

  4. Interactive orbital proximity operations planning system

    NASA Technical Reports Server (NTRS)

    Grunwald, Arthur J.; Ellis, Stephen R.

    1989-01-01

    An interactive, graphical proximity operations planning system was developed which allows on-site design of efficient, complex, multiburn maneuvers in the dynamic multispacecraft environment about the space station. Maneuvering takes place in, as well as out of, the orbital plane. The difficulty in planning such missions results from the unusual and counterintuitive character of relative orbital motion trajectories and complex operational constraints, which are both time varying and highly dependent on the mission scenario. This difficulty is greatly overcome by visualizing the relative trajectories and the relative constraints in an easily interpretable, graphical format, which provides the operator with immediate feedback on design actions. The display shows a perspective bird's-eye view of the space station and co-orbiting spacecraft on the background of the station's orbital plane. The operator has control over two modes of operation: (1) a viewing system mode, which enables him or her to explore the spatial situation about the space station and thus choose and frame in on areas of interest; and (2) a trajectory design mode, which allows the interactive editing of a series of way-points and maneuvering burns to obtain a trajectory which complies with all operational constraints. Through a graphical interactive process, the operator will continue to modify the trajectory design until all operational constraints are met. The effectiveness of this display format in complex trajectory design is presently being evaluated in an ongoing experimental program.

  5. Proximity Resonance and Localized Surface Plasmons

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Heller, Eric

    2014-03-01

    The collective excitation of conduction electrons in subwavelength nanostructures is known as Localized Surface Plasmon(LSP)[1]. Such plasmon modes has been intensively studied using noble nanoparticles . More recently, the possibility of building terahertz metamaterials supporting such LSP modes has been explored in graphene microribbons and microdisks. Unlike Surface Plasmon Polaritons(SPPs) at metal-insulator interface, LSP can be directly excited by light illumination and holds promise for applications in ultrasensitive biosensing, nano-optical tweezers and improved photovoltaic devices. In this paper, we consider the interaction of two LSPs in the weak coupling regime and show how an effect similar to the proximity resonance in the quantum scattering theory) gives rise to an asymmetric(quadrupole) mode with increased damping rate. The existence of this asymmetric mode relies on a small phase retardation between the two LSPs. This phase retardation, though small, is key to both increased damping rate for the asymmetric mode and reduced damping rate for the symmetric mode. When this small phase retardation is removed by changing the polarization of the exciting light,we show that the asymmetric mode can not be excited and the symmetric mode shows increased damping.

  6. Interactive orbital proximity operations planning system

    NASA Technical Reports Server (NTRS)

    Grunwald, Arthur J.; Ellis, Stephen R.

    1988-01-01

    An interactive graphical proximity operations planning system was developed, which allows on-site design of efficient, complex, multiburn maneuvers in a dynamic multispacecraft environment. Maneuvering takes place in and out of the orbital plane. The difficulty in planning such missions results from the unusual and counterintuitive character of orbital dynamics and complex time-varying operational constraints. This difficulty is greatly overcome by visualizing the relative trajectories and the relevant constraints in an easily interpretable graphical format, which provides the operator with immediate feedback on design actions. The display shows a perspective bird's-eye view of a Space Station and co-orbiting spacecraft on the background of the Station's orbital plane. The operator has control over the two modes of operation: a viewing system mode, which enables the exporation of the spatial situation about the Space Station and thus the ability to choose and zoom in on areas of interest; and a trajectory design mode, which allows the interactive editing of a series of way points and maneuvering burns to obtain a trajectory that complies with all operational constraints. A first version of this display was completed. An experimental program is planned in which operators will carry out a series of design missions which vary in complexity and constraints.

  7. Imaging of rectus femoris proximal tendinopathies.

    PubMed

    Pesquer, Lionel; Poussange, Nicolas; Sonnery-Cottet, Bertrand; Graveleau, Nicolas; Meyer, Philippe; Dallaudiere, Benjamin; Feldis, Matthieu

    2016-07-01

    The rectus femoris is the most commonly injured muscle of the anterior thigh among athletes, especially soccer players. Although the injury pattern of the muscle belly is well documented, less is known about the anatomy and specific lesions of the proximal tendons. For each head, three distinctive patterns may be encountered according to the location of the injury, which can be at the enthesis, within the tendon, or at the musculotendinous junction. In children, injuries correspond most commonly to avulsion of the anteroinferior iliac spine from the direct head and can lead to subspine impingement. Calcific tendinitis and traumatic tears may be encountered in adults. Recent studies have shown that traumatic injuries of the indirect head may be underdiagnosed and that injuries of both heads may have a surgical issue. Finally, in the case of tears, functional outcome and treatment may vary if the rupture involves one or both tendons and if the tear is partial or complete. Thus, it is mandatory for the radiologist to know the different ultrasound and magnetic resonance imaging (MRI) patterns of these lesions in order to provide accurate diagnosis and treatment. The purpose of this article is to recall the anatomy of the two heads of rectus femoris, describe a reliable method of assessment with ultrasound and MRI and know the main injury patterns, through our own experience and literature review. PMID:26956398

  8. Extensor mechanism reconstruction after proximal tibial replacement.

    PubMed

    Oddy, M J; Pendegrass, C J; Goodship, A E; Cannon, S R; Briggs, T W R; Blunn, G W

    2005-06-01

    We developed an in vivo model of the attachment of a patellar tendon to a metal implant to simulate the reconstruction of an extensor mechanism after replacement of the proximal tibia. In 24 ewes, the patellar tendon was attached to a hydroxyapatite (HA)-coated titanium prosthesis. In 12, the interface was augmented with autograft containing cancellous bone and marrow. In the remaining ewes, the interface was not grafted. Kinematic gait analysis showed nearly normal function of the joint by 12 weeks. Force-plate assessment showed a significant increase in functional weight-bearing in the grafted animals (p = 0.043). The tendon-implant interface showed that without graft, encapsulation of fibrous tissue occurred. With autograft, a developing tendon-bone-HA-implant interface was observed at six weeks and by 12 weeks a layered tendon-fibrocartilage-bone interface was seen which was similar to a direct-type enthesis. With stable mechanical fixation, an appropriate bioactive surface and biological augmentation the development of a functional tendon-implant interface can be achieved. PMID:15911677

  9. Semiconductor detectors with proximity signal readout

    SciTech Connect

    Asztalos, Stephen J.

    2014-01-30

    Semiconductor-based radiation detectors are routinely used for the detection, imaging, and spectroscopy of x-rays, gamma rays, and charged particles for applications in the areas of nuclear and medical physics, astrophysics, environmental remediation, nuclear nonproliferation, and homeland security. Detectors used for imaging and particle tracking are more complex in that they typically must also measure the location of the radiation interaction in addition to the deposited energy. In such detectors, the position measurement is often achieved by dividing or segmenting the electrodes into many strips or pixels and then reading out the signals from all of the electrode segments. Fine electrode segmentation is problematic for many of the standard semiconductor detector technologies. Clearly there is a need for a semiconductor-based radiation detector technology that can achieve fine position resolution while maintaining the excellent energy resolution intrinsic to semiconductor detectors, can be fabricated through simple processes, does not require complex electrical interconnections to the detector, and can reduce the number of required channels of readout electronics. Proximity electrode signal readout (PESR), in which the electrodes are not in physical contact with the detector surface, satisfies this need.

  10. Ranging/tracking system for proximity operations

    NASA Technical Reports Server (NTRS)

    Nilsen, P.; Udalov, S.

    1982-01-01

    The hardware development and testing phase of a hand held radar for the ranging and tracking for Shuttle proximity operations are considered. The radar is to measure range to a 3 sigma accuracy of 1 m (3.28 ft) to a maximum range of 1850 m (6000 ft) and velocity to a 3 sigma accuracy of 0.03 m/s (0.1 ft/s). Size and weight are similar to hand held radars, frequently seen in use by motorcycle police officers. Meeting these goals for a target in free space was very difficult to obtain in the testing program; however, at a range of approximately 700 m, the 3 sigma range error was found to be 0.96 m. It is felt that much of this error is due to clutter in the test environment. As an example of the velocity accuracy, at a range of 450 m, a 3 sigma velocity error of 0.02 m/s was measured. The principles of the radar and recommended changes to its design are given. Analyses performed in support of the design process, the actual circuit diagrams, and the software listing are included.

  11. Bilateral non-osteochondroma-related proximal tibiofibular synostosis.

    PubMed

    Wakayama, Takanori; Imanishi, Jungo; Yazawa, Yasuo; Okubo, Taketo; Kaneko, Kazuo

    2014-12-01

    We report the case of a 67-year-old male with bilateral proximal tibiofibular synostosis, presenting with unilateral symptoms. The patient complained of pain around the left fibular head, which was attributed to incomplete bone bridging between the proximal tibia and fibula; he underwent proximal fibular head resection, which alleviated the pain and improved knee mobility. Eleven months later, the patient continued to be pain-free and did not experience any adverse effects. An examination of this case and a review of similar cases revealed that participation in sport activities such as long-distance running may be one of the causes of proximal tibiofibular synostosis. In this report, we have also reconsidered the classification of proximal tibiofibular synostosis and provided information for a better understanding of this unusual condition. PMID:24915740

  12. Preventing Proximal Adjacent Level Kyphosis With Strap Stabilization.

    PubMed

    Zaghloul, Khaled M; Matoian, Brett J; Denardin, Nicholas B; Patel, Vikas V

    2016-07-01

    A substantial proportion of patients develop proximal junctional kyphosis following spinal surgery. To combat this postoperative change, several techniques have focused on maintaining the structural integrity of adjacent spinal levels and adapting the proximal end of the fusion construct to accommodate the increased mechanical stressors produced by long spinal fusion. The use of Mersilene tape (Ethicon, Somerville, New Jersey) for spine and orthopedic surgery is well documented, although considerably less is known about its use for preventing proximal junctional kyphosis. This article describes a proposed technique using Mersilene tape to provide a check-rein strap stabilization at the proximal end of fusion constructs. Initial data suggest that use of this technique may prevent formation of proximal junctional kyphosis. [Orthopedics. 2016; 39(4):e794-e799.]. PMID:27158827

  13. Molecular interactions between albumin and proximal tubular cells.

    PubMed

    Brunskill, N J

    1998-01-01

    In glomerular diseases the filtration of excess proteins into the proximal tubule, together with their subsequent reabsorption may represent an important pathological mechanism underlying progressive renal scarring. The most prominent protein in glomerular filtrate, albumin, is reabsorbed by receptor-mediated endocytosis by proximal tubular cells. It binds both to scavenger-type receptors and to megalin in the proximal tubule. Some of these receptors appear to be shared with other cell types, particularly endothelial cells. The endocytic uptake of albumin is subjected to complex hormonal and enzymatic regulation. In addition to being reabsorbed in the proximal tubule, albumin may act as a signalling molecule in these cells, and may induce the expression of numerous pro-inflammatory genes. Modulation of the interaction of albumin with proximal tubular cells may eventually prove to be of therapeutic importance in the treatment of renal diseases. PMID:9807019

  14. Mechanisms of albumin uptake by proximal tubular cells.

    PubMed

    Brunskill, N

    2001-01-01

    The likely role of albumin in the induction tubulo-interstitial injury in proteinuria has stimulated considerable interest in the entry of albumin into the proximal tubule and its subsequent uptake by proximal tubular cells. Currently, there is considerable controversy over the degree of glomerular permeability to albumin. After filtration, however, albumin binds to megalin and cubulin, two giant receptors in the apical membrane of proximal tubular cells. Albumin is subsequently re-absorbed by proximal tubular cells by receptor-mediated endocytosis, a process subject to complex regulation. The interaction of albumin with proximal tubule cells also leads to the generation of intracellular signals. The understanding of these pathways may provide important insights into the pathogenesis of renal scarring in proteinuria. PMID:11158855

  15. Estimation of optical proximity effect caused by mask fabrication error

    NASA Astrophysics Data System (ADS)

    Kamon, Kazuya; Hanawa, Tetsuro; Moriizumi, Koichi

    1997-07-01

    To get wide lithography latitudes in ULSI fabrication, an optical proximity correction system is being widely used. We previously demonstrated that the optical proximity effect is highly dependent on beam interference conditions. By using an aperture with a spindle shaped opaque region and a controlling interference beam number optimized for imaging, we can obtain a high correction accuracy of less than +/- 0.01 micrometers for all kinds of pattern. To put the optical proximity correction into practical use, we must fabricate the corrected mask either by an EB or a laser writing system. But during mask writing, there is another problematic proximity effect. The optical proximity effect caused by mask fabrication error is becoming a serious problem. In this paper, we estimate the optical proximity effect caused by mask fabrication error. For EB writing, the mask feature size of 0.35 micrometers line changes dramatically in a space less than 0.8 micrometers in size; this is not tolerable. For a large pitch pattern, modified illumination reduces the DOF to 0 micrometers . Otherwise, laser writing stably fabricates a mask feature size for a 0.35 micrometers line, and the modified illumination reduces the optical proximity effect. This resist feature fluctuation is binary, so, correcting the mask pattern is easy. Although, it was wrongly thought that for larger pitch pattern, the DOF was reduced by the modified illumination, the DOF reduction actually came from the combination of the two proximity effects. Using an accurate mask produced by a laser writer, we do not observe any DOF reduction in modified illumination. Moreover, this has led to development of an optical proximity correction system with EB proximity correction.

  16. Transport Magnetic Proximity Effects in Platinum

    NASA Astrophysics Data System (ADS)

    Huang, Ssu-Yen

    2013-03-01

    Platinum (Pt) metal, being non-magnetic and having a strong spin-orbit coupling interaction, has been central in detecting pure spin current and establishing most of the recent spin-based phenomena. Thus, it is important to ascertain the transport and magnetic characteristics of thin Pt films in contact with a ferromagnet. In this work, we use both electric and thermal means to conclusively show the transport magnetic proximity effects (MPE) of thin Pt film in contact with ferromagnetic insulator YIG. At thicknesses comparable to, and less than, the spin diffusion length, the strong ferromagnetic characteristics in Pt films on YIG are indistinguishable from those of ferromagnetic permalloy on YIG. The MPE occurs at the interface and decreases exponentially away from the interface, concentrating in only a few monolayers. As a result, the pure spin current detected by a thin Pt is tainted with a spin polarized current. The pure spin current phenomena, such as the inverse spin Hall effect and the spin Seebeck effect, have been contaminated with the anomalous Hall effect and the anomalous Nernst effect respectively. These results raise serious questions about the suitability, and the validity, of using Pt in establishing pure spin current phenomena; on the other hand, a much stronger spin-based effect can be induced by the MPE at the interface. This research is in collaboration with X. Fin, Y. P. Chen, J. Wu, and J. Q. Xiao (University of Delaware), T. Y. Chen (Arizona State University) and D. Qu, W. G. Wang, and C. L. Chien (The Johns Hopkins University).

  17. Hypospadias and Residential Proximity to Pesticide Applications

    PubMed Central

    Yang, Wei; Roberts, Eric M.; Kegley, Susan E.; Wolff, Craig; Guo, Liang; Lammer, Edward J.; English, Paul; Shaw, Gary M.

    2013-01-01

    BACKGROUND: Experimental evidence suggests pesticides may be associated with hypospadias. OBJECTIVE: Examine the association of hypospadias with residential proximity to commercial agricultural pesticide applications. METHODS: The study population included male infants born from 1991 to 2004 to mothers residing in 8 California counties. Cases (n = 690) were ascertained by the California Birth Defects Monitoring Program; controls were selected randomly from the birth population (n = 2195). We determined early pregnancy exposure to pesticide applications within a 500-m radius of mother’s residential address, using detailed data on applications and land use. Associations with exposures to physicochemical groups of pesticides and specific chemicals were assessed using logistic regression adjusted for maternal race or ethnicity and age and infant birth year. RESULTS: Forty-one percent of cases and controls were classified as exposed to 57 chemical groups and 292 chemicals. Despite >500 statistical comparisons, there were few elevated odds ratios with confidence intervals that excluded 1 for chemical groups or specific chemicals. Those that did were for monochlorophenoxy acid or ester herbicides; the insecticides aldicarb, dimethoate, phorate, and petroleum oils; and adjuvant polyoxyethylene sorbitol among all cases; 2,6-dinitroaniline herbicides, the herbicide oxyfluorfen, and the fungicide copper sulfate among mild cases; and chloroacetanilide herbicides, polyalkyloxy compounds used as adjuvants, the insecticides aldicarb and acephate, and the adjuvant nonyl-phenoxy-poly(ethylene oxy)ethanol among moderate and severe cases. Odds ratios ranged from 1.9 to 2.9. CONCLUSIONS: Most pesticides were not associated with elevated hypospadias risk. For the few that were associated, results should be interpreted with caution until replicated in other study populations. PMID:24167181

  18. Nanocrystal Bioassembly: Asymmetry, Proximity, and Enzymatic Manipulation

    SciTech Connect

    Claridge, Shelley A.

    2008-05-01

    Research at the interface between biomolecules and inorganic nanocrystals has resulted in a great number of new discoveries. In part this arises from the synergistic duality of the system: biomolecules may act as self-assembly agents for organizing inorganic nanocrystals into functional materials; alternatively, nanocrystals may act as microscopic or spectroscopic labels for elucidating the behavior of complex biomolecular systems. However, success in either of these functions relies heavily uponthe ability to control the conjugation and assembly processes.In the work presented here, we first design a branched DNA scaffold which allows hybridization of DNA-nanocrystal monoconjugates to form discrete assemblies. Importantly, the asymmetry of the branched scaffold allows the formation of asymmetric2assemblies of nanocrystals. In the context of a self-assembled device, this can be considered a step toward the ability to engineer functionally distinct inputs and outputs.Next we develop an anion-exchange high performance liquid chromatography purification method which allows large gold nanocrystals attached to single strands of very short DNA to be purified. When two such complementary conjugates are hybridized, the large nanocrystals are brought into close proximity, allowing their plasmon resonances to couple. Such plasmon-coupled constructs are of interest both as optical interconnects for nanoscale devices and as `plasmon ruler? biomolecular probes.We then present an enzymatic ligation strategy for creating multi-nanoparticle building blocks for self-assembly. In constructing a nanoscale device, such a strategy would allow pre-assembly and purification of components; these constructs can also act as multi-label probes of single-stranded DNA conformational dynamics. Finally we demonstrate a simple proof-of-concept of a nanoparticle analog of the polymerase chain reaction.

  19. Coupled water transport by rat proximal tubule.

    PubMed

    Green, R; Giebisch, G; Unwin, R; Weinstein, A M

    1991-12-01

    Simultaneous microperfusion of proximal tubules and peritubular capillaries in kidneys of rats anesthetized with Inactin was used to examine water reabsorption by this epithelium. Osmolality of the luminal solution was varied with changes in NaCl concentration and by the addition of raffinose. Capillary perfusates contained either low (2 g/dl) or high (16 g/dl) concentrations of albumin. We used low-bicarbonate perfusates for both lumen and capillary so that we might apply the nonequilibrium thermodynamic model of transport for a single solute (NaCl) to interpret our observations. Linear regression with the volume flux equation Jv = -Lp delta II - Lp sigma delta C + Jav (where Jv is volume flux, Lp is hydraulic conductance, delta II is oncotic force, sigma is osmotic reflection coefficient, delta C is salt concentration difference, and Jav is the component of Jv not attributed to transepithelial hydrostatic or osmotic forces) revealed a tubule water permeability (Pf = 0.11 +/- 0.01 cm/s) and a sigma (0.74 +/- 0.08) in agreement with previous determinations. These transport parameters were unaffected by changes in peritubular protein. We also found that Jav was substantial, approximately three-fourths of the rate of isotonic transport under these perfusion conditions. Further, this component of water transport nearly doubled with the transition from low- to high-protein peritubular capillary perfusion. When expressed as a capacity for water reabsorption against an osmotic gradient, the salt concentration differences required to null volume flux were 13.2 +/- 2.4 and 29.4 +/- 4.0 mosmol/kgH2O under low and high peritubular protein. Our data suggest that this protein effect is, most likely, an increase in solute transport by the tubule epithelial cells. PMID:1750518

  20. Promoting Models

    NASA Astrophysics Data System (ADS)

    Li, Qin; Zhao, Yongxin; Wu, Xiaofeng; Liu, Si

    There can be multitudinous models specifying aspects of the same system. Each model has a bias towards one aspect. These models often override in specific aspects though they have different expressions. A specification written in one model can be refined by introducing additional information from other models. The paper proposes a concept of promoting models which is a methodology to obtain refinements with support from cooperating models. It refines a primary model by integrating the information from a secondary model. The promotion principle is not merely an academic point, but also a reliable and robust engineering technique which can be used to develop software and hardware systems. It can also check the consistency between two specifications from different models. A case of modeling a simple online shopping system with the cooperation of the guarded design model and CSP model illustrates the practicability of the promotion principle.

  1. Murine natural killer immunoreceptors use distinct proximal signaling complexes to direct cell function

    PubMed Central

    May, Rebecca M.; Okumura, Mariko; Hsu, Chin-Jung; Bassiri, Hamid; Yang, Enjun; Rak, Gregory; Mace, Emily M.; Philip, Naomi H.; Zhang, Weiguo; Baumgart, Tobias; Orange, Jordan S.; Nichols, Kim E.

    2013-01-01

    Signaling pathways leading to natural killer (NK)–cell effector function are complex and incompletely understood. Here, we investigated the proximal signaling pathways downstream of the immunotyrosine-based activation motif (ITAM) bearing activating receptors. We found that the adaptor molecule SH2 domain-containing leukocyte protein of 76 kD (SLP-76) is recruited to microclusters at the plasma membrane in activated NK cells and that this is required for initiation of downstream signaling and multiple NK-cell effector functions in vitro and in vivo. Surprisingly, we found that 2 types of proximal signaling complexes involving SLP-76 were formed. In addition to the canonical membrane complex formed between SLP-76 and linker for activation of T cells (LAT) family members, a novel LAT family–independent SLP-76–dependent signaling pathway was identified. The LAT family–independent pathway involved the SH2 domain of SLP-76 and adhesion and degranulation-promoting adaptor protein (ADAP). Both the LAT family–dependent and ADAP-dependent pathway contributed to interferon-gamma production and cytotoxicity; however, they were not essential for other SLP-76–dependent events, including phosphorylation of AKT and extracellular signal–related kinase and cellular proliferation. These results demonstrate that NK cells possess an unexpected bifurcation of proximal ITAM-mediated signaling, each involving SLP-76 and contributing to optimal NK-cell function. PMID:23407547

  2. Repair of esophageal atresia with proximal fistula using endoscopic magnetic compression anastomosis (magnamosis) after staged lengthening.

    PubMed

    Dorman, Robert M; Vali, Kaveh; Harmon, Carroll M; Zaritzky, Mario; Bass, Kathryn D

    2016-05-01

    We describe the treatment of a patient with long-gap esophageal atresia with an upper pouch fistula, mircogastria and minimal distal esophageal remnant. After 4.5 months of feeding via gastrostomy, a proximal fistula was identified by bronchoscopy and a thoracoscopic modified Foker procedure was performed reducing the gap from approximately 7-5 cm over 2 weeks of traction. A second stage to ligate the fistula and suture approximate the proximal and distal esophagus resulted in a gap of 1.5 cm. IRB and FDA approval was then obtained for endoscopic placement of 10-French catheter mounted magnets in the proximal and distal pouches promoting a magnetic compression anastomosis (magnamosis). Magnetic coupling occurred at 4 days and after magnet removal at 13 days an esophagram demonstrated a 10 French channel without leak. Serial endoscopic balloon dilation has allowed drainage of swallowed secretions as the baby learns bottling behavior at home. PMID:27012861

  3. Cancer rates after the Three Mile Island nuclear accident and proximity of residence to the plant.

    PubMed Central

    Hatch, M C; Wallenstein, S; Beyea, J; Nieves, J W; Susser, M

    1991-01-01

    BACKGROUND: In the light of a possible link between stress and cancer promotion or progression, and of previously reported distress in residents near the Three Mile Island (TMI) nuclear power plant, we attempted to evaluate the impact of the March 1979 accident on community cancer rates. METHODS: Proximity of residence to the plant, which related to distress in previous studies, was taken as a possible indicator of accident stress; the postaccident pattern in cancer rates was examined in 69 "study tracts" within a 10-mile radius of TMI, in relation to residential proximity. RESULTS: A modest association was found between postaccident cancer rates and proximity (OR = 1.4; 95% CI = 1.3, 1.6). After adjusting for a gradient in cancer risk prior to the accident, the odds ratio contrasting those closest to the plant with those living farther out was 1.2 (95% CI = 1.0, 1.4). A postaccident increase in cancer rates near the Three Mile Island plant was notable in 1982, persisted for another year, and then declined. Radiation emissions, as modeled mathematically, did not account for the observed increase. CONCLUSION: Interpretation in terms of accident stress is limited by the lack of an individual measure of stress and by uncertainty about whether stress has a biological effect on cancer in humans. An alternative mechanism for the cancer increase near the plant is through changes in care-seeking and diagnostic practice arising from postaccident concern. PMID:2029040

  4. Promoting Health.

    ERIC Educational Resources Information Center

    Mechanic, David

    1990-01-01

    Argues that culture change or modification of the social structure is necessary for effective health promotion because health behavior is closely tied to basic group structures and processes. Examines the health attitudes of Mormons, low income and minority groups, and developing Islamic nations, emphasizing attitudes towards education and women.…

  5. Differentiated kidney epithelial cells repair injured proximal tubule.

    PubMed

    Kusaba, Tetsuro; Lalli, Matthew; Kramann, Rafael; Kobayashi, Akio; Humphreys, Benjamin D

    2014-01-28

    Whether kidney proximal tubule harbors a scattered population of epithelial stem cells is a major unsolved question. Lineage-tracing studies, histologic characterization, and ex vivo functional analysis results conflict. To address this controversy, we analyzed the lineage and clonal behavior of fully differentiated proximal tubule epithelial cells after injury. A CreER(T2) cassette was knocked into the sodium-dependent inorganic phosphate transporter SLC34a1 locus, which is expressed only in differentiated proximal tubule. Tamoxifen-dependent recombination was absolutely specific to proximal tubule. Clonal analysis after injury and repair showed that the bulk of labeled cells proliferate after injury with increased clone size after severe compared with mild injury. Injury to labeled proximal tubule epithelia induced expression of CD24, CD133, vimentin, and kidney-injury molecule-1, markers of putative epithelial stem cells in the human kidney. Similar results were observed in cultured proximal tubules, in which labeled clones proliferated and expressed dedifferentiation and injury markers. When mice with completely labeled kidneys were subject to injury and repair there was no dilution of fate marker despite substantial proliferation, indicating that unlabeled progenitors do not contribute to kidney repair. During nephrogenesis and early kidney growth, single proximal tubule clones expanded, suggesting that differentiated cells also contribute to tubule elongation. These findings provide no evidence for an intratubular stem-cell population, but rather indicate that terminally differentiated epithelia reexpress apparent stem-cell markers during injury-induced dedifferentiation and repair. PMID:24127583

  6. Closed proximal muscle rupture of the biceps brachii in wakeboarders.

    PubMed

    Pascual-Garrido, Cecilia; Swanson, Britta L; Bannar, Stephen M

    2012-06-01

    Closed proximal muscle rupture of the biceps brachii is a rare injury. In this report, two cases of closed proximal muscle rupture of the biceps brachii after wakeboard traumas are described. Both patients presented with a swollen arm, weakness during flexion, and a mass in the affected forearm. Magnetic resonance imaging showed displacement of the biceps brachii into the forearm. The rupture was successfully treated with muscle removal in one case and muscle repair in the other. In patients with a wakeboard trauma and similar presentations, closed proximal muscle rupture of the biceps brachii should be suspected. PMID:21877295

  7. Maximal Expression of the Evolutionarily Conserved Slit2 Gene Promoter Requires Sp1.

    PubMed

    Saunders, Jacquelyn; Wisidagama, D Roonalika; Morford, Travis; Malone, Cindy S

    2016-08-01

    Slit2 is a neural axon guidance and chemorepellent protein that stimulates motility in a variety of cell types. The role of Slit2 in neural development and neoplastic growth and migration has been well established, while the genetic mechanisms underlying regulation of the Slit2 gene have not. We identified the core and proximal promoter of Slit2 by mapping multiple transcriptional start sites, analyzing transcriptional activity, and confirming sequence homology for the Slit2 proximal promoter among a number of species. Deletion series and transient transfection identified the Slit2 proximal promoter as within 399 base pairs upstream of the start of transcription. A crucial region for full expression of the Slit2 proximal promoter lies between 399 base pairs and 296 base pairs upstream of the start of transcription. Computer modeling identified three transcription factor-binding consensus sites within this region, of which only site-directed mutagenesis of one of the two identified Sp1 consensus sites inhibited transcriptional activity of the Slit2 proximal promoter (-399 to +253). Bioinformatics analysis of the Slit2 proximal promoter -399 base pair to -296 base pair region shows high sequence conservation over twenty-two species, and that this region follows an expected pattern of sequence divergence through evolution. PMID:26456684

  8. Effective molarity redux: Proximity as a guiding force in chemistry and biology.

    PubMed

    Hobert, Elissa M; Doerner, Amy E; Walker, Allison S; Schepartz, Alanna

    2013-08-01

    The cell interior is a complex and demanding environment. An incredible variety of molecules jockey to identify the correct position-the specific interactions that promote biology that are hidden among countless unproductive options. Ensuring that the business of the cell is successful requires sophisticated mechanisms to impose temporal and spatial specificity-both on transient interactions and their eventual outcomes. Two strategies employed to regulate macromolecular interactions in a cellular context are co-localization and compartmentalization. Macromolecular interactions can be promoted and specified by localizing the partners within the same subcellular compartment, or by holding them in proximity through covalent or non-covalent interactions with proteins, lipids, or DNA- themes that are familiar to any biologist. The net result of these strategies is an increase in effective molarity: the local concentration of a reactive molecule near its reaction partners. We will focus on this general mechanism, employed by Nature and adapted in the lab, which allows delicate control in complex environments: the power of proximity to accelerate, guide, or otherwise influence the reactivity of signaling proteins and the information that they encode. PMID:25418998

  9. Challenger's RMS arm grasps SPAS-01 during proximity operations

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Challenger's remote manipulator system (RMS) arm grasps Shuttle pallet satellite (SPAS-01) during proximity operations. The frame shows a number of reflections on the window, located overhead in the aft flight deck.

  10. An unusual case of glipizide-induced proximal myopathy

    PubMed Central

    Das, Saibal; Ramasamy, Anand; De, Soumyadip; Mondal, Somnath

    2016-01-01

    This case report outlines a very rare case of glipizide-induced severe proximal myopathy in a 61-year-old diabetic man. After taking 10 mg glipizide for 5 months, diabetes was well controlled but the patient presented with progressive proximal muscle weakness in all the four limbs. Clinical examination and relevant investigations suggested it to be a case of proximal myopathy and might be drug induced. De-challenge was done and was treated resulting in reversal of the diseased state. After 3 more months, controlled re-challenge was done and there was recurrence of proximal muscle weakness. There were no evidences of any other possible metabolic, infective, organic or other pathologic causes giving rise to that condition and Naranjo adverse drug reaction probability scale suggested that it was “probable” that glipizide was responsible for the development of myopathy in this patient. PMID:27440956