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  • American Heart Association (AHA)  (62)
  • The American Physiological Society (APS)  (62)
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  • 1
    Publication Date: 2016-02-17
    Description: Background— There is increasing evidence that retinal microvascular diameters are associated with cardiovascular and cerebrovascular conditions. The shared genetic effects of these associations are currently unknown. The aim of this study was to increase our understanding of the genetic factors that mediate retinal vessel size. Methods and Results— This study extends previous genome-wide association study results using 24 000+ multiethnic participants from 7 discovery cohorts and 5000+ subjects of European ancestry from 2 replication cohorts. Using the Illumina HumanExome BeadChip, we investigate the association of single-nucleotide polymorphisms and variants collectively across genes with summary measures of retinal vessel diameters, referred to as the central retinal venule equivalent and the central retinal arteriole equivalent. We report 4 new loci associated with central retinal venule equivalent, one of which is also associated with central retinal arteriole equivalent. The 4 single-nucleotide polymorphisms are rs7926971 in TEAD1 ( P =3.1 x 10 – 11 ; minor allele frequency=0.43), rs201259422 in TSPAN10 ( P =4.4 x 10 –9 ; minor allele frequency=0.27), rs5442 in GNB3 ( P =7.0 x 10 –10 ; minor allele frequency=0.05), and rs1800407 in OCA2 ( P =3.4 x 10 –8 ; minor allele frequency=0.05). The latter single-nucleotide polymorphism, rs1800407, was also associated with central retinal arteriole equivalent ( P =6.5 x 10 –12 ). Results from the gene-based burden tests were null. In phenotype look-ups, single-nucleotide polymorphism rs201255422 was associated with both systolic ( P =0.001) and diastolic blood pressures ( P =8.3 x 10 –04 ). Conclusions— Our study expands the understanding of genetic factors influencing the size of the retinal microvasculature. These findings may also provide insight into the relationship between retinal and systemic microvascular disease.
    Keywords: Basic Science Research
    Print ISSN: 1942-325X
    Electronic ISSN: 1942-3268
    Topics: Medicine
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  • 2
    Publication Date: 2012-05-16
    Description: Autosomal dominant polycystic kidney disease (ADPKD) is a common inherited disease characterized by massive enlargement of fluid-filled cysts in the kidney. However, there is no effective therapy yet for this disease. To examine whether ginkgolide B, a natural compound, inhibits cyst development, a Madin-Darby canine kidney (MDCK) cyst model, an embryonic kidney cyst model, and a PKD mouse model were used. Interestingly, ginkgolide B significantly inhibited MDCK cyst formation dose dependently, with up to 69% reduction by 2 μM ginkgolide B. Ginkgolide B also significantly inhibited cyst enlargement in the MDCK cyst model, embryonic kidney cyst model, and PKD mouse model. To determine the underlying mechanisms, the effect of ginkgolide B on MDCK cell viability, proliferation, apoptosis, chloride transporter CFTR activity, and intracellular signaling pathways were also studied. Ginkgolide B did not affect cell viability, proliferation, and expression and activity of the chloride transporter CFTR that mediates cyst fluid secretion. Ginkgolide B induced cyst cell differentiation and altered the Ras/MAPK signaling pathway. Taken together, our results demonstrate that ginkgolide B inhibits renal cyst formation and enlargement, suggesting that ginkgolide B might be developed into a novel candidate drug for ADPKD.
    Print ISSN: 1931-857X
    Electronic ISSN: 1522-1466
    Topics: Medicine
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  • 3
    Publication Date: 2015-02-27
    Description: Objective— Tyrosine kinase receptor B (TrkB) is a high-affinity receptor for brain-derived neurotrophic factor. In addition to its nervous system functions, TrkB is also expressed in the cardiovascular system. However, the association of TrkB and coronary artery disease (CAD) remains unknown. We investigated the role of TrkB in the development of CAD and its mechanism. Approach and Results— We performed a case–control study in 2 independent cohort of Chinese subjects and found –69C〉G polymorphisms of TrkB gene significantly associated with CAD. TrkB –69C homozygotes, which corresponded to decreased TrkB expression by luciferase reporter assay, showed increased risk for CAD. Immunofluorescence analysis revealed that TrkB was expressed in the aortic endothelium in atherosclerotic lesions in humans and ApoE –/– mice. TrkB knockdown in the aortic endothelium resulted in vascular leakage in ApoE –/– mice. Mechanistic studies showed that TrkB regulated vascular endothelial cadherin (VE-cadherin) expression through induction and activation of Ets1 transcriptional factor. Importantly, TrkB activation attenuated proatherosclerotic factors induced-endothelial hyperpermeability in human vascular endothelial cells. Conclusions— Our data demonstrate that TrkB protects endothelial integrity during atherogenesis by promoting Ets1-mediated VE-cadherin expression and plays a previously unknown protective role in the development of CAD.
    Keywords: Cell biology/structural biology, Genetics of cardiovascular disease
    Print ISSN: 1079-5642
    Electronic ISSN: 1524-4636
    Topics: Medicine
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  • 4
    Publication Date: 2016-01-02
    Description: Inflammation-dominated sympathetic sprouting adjacent to the necrotic region following myocardial infarction (MI) has been implicated in the etiology of arrhythmias resulting in sudden cardiac death; however, the mechanisms responsible remain to be elucidated. Although being a key immune mediator, the role of Notch has yet to be explored. We investigated whether Notch regulates macrophage responses to inflammation and affects cardiac sympathetic reinnervation in rats undergoing MI. MI was induced by coronary artery ligation. A high level of Notch intracellular domain was observed in the macrophages that infiltrated the infarct area at 3 days post-MI. The administration of the Notch inhibitor N-N-(3,5-difluorophenacetyl- l -alanyl)-S-phenylglycine-t-butyl ester (DAPT) (intravenously 30 min before MI and then daily until death) decreased the number of macrophages and significantly increased the M2 macrophage activation profile in the early stages and attenuated the expression of nerve growth factor (NGF). Eventually, NGF-induced sympathetic hyperinnervation was blunted, as assessed by the immunofluorescence of tyrosine hydroxylase. At 7 days post-MI, the arrhythmia score of programmed electric stimulation in the vehicle-treated infarcted rats was higher than that in rats treated with DAPT. Further deterioration in cardiac function and decreases in the plasma levels of TNF-α and IL-1β were also detected. In vitro studies revealed that LPS/IFN- upregulated the surface expression of NGF in M1 macrophages in a Notch-dependent manner. We concluded that Notch inhibition during the acute inflammatory response phase is associated with the downregulation of NGF, probably through a macrophage-dependent pathway, thus preventing the process of sympathetic hyperinnervation.
    Print ISSN: 0363-6143
    Electronic ISSN: 1522-1563
    Topics: Medicine
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  • 5
    Publication Date: 2016-12-03
    Description: Bisphenol A diglycidyl ether (BADGE), a PPAR2 antagonist, has been shown to inhibit marrow adipogenesis and promote bone formation in intact animals. We investigated the impact of BADGE on a new and more clinically relevant physiological model, the ovariectomized (OVX) rat model. Forty female Wistar rats were divided into four treatment groups for 12 wk ( n = 10/group): sham+vehicle, sham+BADGE, OVX+vehicle, and OVX+BADGE. Postmortem analyses included MRI, micro-CT, serological test, histomorphometry, biomechanical tests, RT-PCR, and Western blot. Overall, OVX induced a sequential marrow fat expansion accompanied by bone deterioration. Compared with OVX controls, BADGE reduced fat fraction of the distal femur by 36.3%, adipocyte density by 33.0%, adipocyte size by 28.6%, adipocyte volume percentage by 57.8%, and adipogenic markers PPAR2 and C/EBPα by ~50% in OVX rats. Similar results were observed in sham rats vs. vehicle. BADGE could promote bone quality in sham rats; however, BADGE did not significantly improve trabecular microarchitecture, biomechanical strength, and dynamic histomorphometric parameters except for trabecular separation in OVX rats. We concluded that early BADGE treatment at a dose of 30 mg/kg attenuates marrow adiposity in ovary-intact and OVX rats and stimulates bone formation in ovary-intact rats but does not significantly rescue bone quality in OVX rats.
    Print ISSN: 0193-1849
    Electronic ISSN: 1522-1555
    Topics: Medicine
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  • 6
    Publication Date: 2014-03-16
    Description: Recent studies in septic models have shown that myocardial calpain activity and TNF-α expression increase during sepsis and that inhibition of calpain activation downregulates myocardial TNF-α expression and improves cardiac dysfunction. However, the mechanism underlying this pathological process is unclear. Thus, in the present study, we aimed to explore whether IBα/NF-B signaling linked myocardial calpain activity and TNF-α expression in septic mice. Adult male mice were injected with LPS (4 mg/kg ip) to induce sepsis. Myocardial calpain activity, IBα/NF-B signaling activity, and TNF-α expression were assessed, and myocardial function was evaluated using the Langendorff system. In septic mice, myocardial calpain activity and TNF-α expression were increased and IBα protein was degraded. Furthermore, NF-B was activated, as indicated by increased NF-B p65 phosphorylation, cleavage of p105 into p50, and its nuclear translocation. Administration of the calpain inhibitors calpain inhibitor and PD-150606 prevented the LPS-induced degradation of myocardial IBα, NF-B activation, and TNF-α expression and ultimately improved myocardial function. In calpastatin transgenic mice, an endogenous calpain inhibitor and cultured neonatal mouse cardiomyocytes overexpressing calpastatin also inhibited calpain activity, IBα protein degradation, and NF-B activation after LPS treatment. In conclusion, myocardial calpain activity was increased in septic mice. Calpain induced myocardial NF-B activation, TNF-α expression, and myocardial dysfunction in septic mice through IBα protein cleavage.
    Print ISSN: 0363-6135
    Electronic ISSN: 1522-1539
    Topics: Medicine
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  • 7
    Publication Date: 2013-12-02
    Description: The mammalian Na + /H + exchanger isoform 1 (NHE1) is a ubiquitous plasma membrane protein that regulates intracellular pH by removing a single proton (H + ) in exchange for one extracellular Na + . The human protein contains a ~500-amino acid membrane domain and a regulatory, ~315-amino acid cytosolic domain. NHE1 is activated by a number of hormones including endothelin (ET) and by Ca 2+ . The regulatory tail possesses an inhibitory calmodulin (CaM)-binding domain, and inhibition of NHE1 is relieved by binding of a Ca 2+ -CaM complex. We examined the dynamics of ET-1 and Ca 2+ regulation of binding to NHE1 in vivo. CFP was linked to the NHE1 protein cytoplasmic COOH terminus. This was stably transfected into AP-1 cells that are devoid of their own NHE1 protein. The protein was expressed and targeted properly and retained NHE1 activity comparable to the wild-type protein. We examined the in vivo coupling of NHE1 to CaM by Förster resonance energy transfer using CaM linked to the fluorescent protein Venus. CaM interaction with NHE1 was dynamic. Removal of serum reduced CaM interaction with NHE1. Addition of the Ca 2+ ionophore ionomycin increased the interaction between CaM and NHE1. We expressed an ET receptor in AP-1 cells and also found a time-dependent association of NHE1 with CaM in vivo that was dependent on ET treatment. The results are the first demonstration of the in vivo association of NHE1 and CaM through ET-dependent signaling pathways.
    Print ISSN: 0363-6143
    Electronic ISSN: 1522-1563
    Topics: Medicine
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  • 8
    Publication Date: 2013-11-26
    Description: Background and Purpose— Bryostatin, a potent protein kinase C (PKC) activator, has demonstrated therapeutic efficacy in preclinical models of associative memory, Alzheimer disease, global ischemia, and traumatic brain injury. In this study, we tested the hypothesis that administration of bryostatin provides a therapeutic benefit in reducing brain injury and improving stroke outcome using a clinically relevant model of cerebral ischemia with tissue plasminogen activator reperfusion in aged rats. Methods— Acute cerebral ischemia was produced by reversible occlusion of the right middle cerebral artery (MCAO) in 18- to 20-month-old female Sprague–Dawley rats using an autologous blood clot with tissue plasminogen activator–mediated reperfusion. Bryostatin was administered at 6 hours post-MCAO, then at 3, 6, 9, 12, 15, and 18 days after MCAO. Functional assessment was conducted at 2, 7, 14, and 21 days after MCAO. Lesion volume and hemispheric swelling/atrophy were performed at 2, 7, and 21 days post-MCAO. Histological assessment of PKC isozymes was performed at 24 hours post-MCAO. Results— Bryostatin-treated rats showed improved survival post-MCAO, especially during the first 4 days. Repeated administration of bryostatin post-MCAO resulted in reduced infarct volume, hemispheric swelling/atrophy, and improved neurological function at 21 days post-MCAO. Changes in αPKC expression and PKC expression in neurons were noted in bryostatin-treated rats at 24 hours post-MCAO. Conclusions— Repeated bryostatin administration post-MCAO protected the brain from severe neurological injury post-MCAO. Bryostatin treatment improved survival rate, reduced lesion volume, salvaged tissue in infarcted hemisphere by reducing necrosis and peri-infarct astrogliosis, and improved functional outcome after MCAO.
    Print ISSN: 0039-2499
    Electronic ISSN: 1524-4628
    Topics: Medicine
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  • 9
    Publication Date: 2013-08-02
    Description: Elevated levels of intracellular Ca 2+ ([Ca 2+ ] i ) inhibit Na + /H + exchanger 3 (NHE3) activity in the intact intestine. We previously demonstrated that PLC- directly binds NHE3, an interaction that is necessary for [Ca 2+ ] i inhibition of NHE3 activity, and that PLC- Src homology 2 (SH2) domains may scaffold Ca 2+ signaling proteins necessary for regulation of NHE3 activity. [Ca 2+ ] i regulation of NHE3 activity is also c-Src dependent; however, the mechanism by which c-Src is involved is undetermined. We hypothesized that the SH2 domains of PLC- might link c-Src to NHE3-containing complexes to mediate [Ca 2+ ] i inhibition of NHE3 activity. In Caco-2/BBe cells, carbachol (CCh) decreased NHE3 activity by ~40%, an effect abolished with the c-Src inhibitor PP2. CCh treatment increased the amount of active c-Src as early as 1 min through increased Y 416 phosphorylation. Coimmunoprecipitation demonstrated that c-Src associated with PLC-, but not NHE3, under basal conditions, an interaction that increased rapidly after CCh treatment and occurred before the dissociation of PLC- and NHE3 that occurred 10 min after CCh treatment. Finally, direct binding to c-Src only occurred through the PLC- SH2 domains, an interaction that was prevented by blocking the PLC- SH2 domain. This study demonstrated that c-Src 1 ) activity is necessary for [Ca 2+ ] i inhibition of NHE3 activity, 2 ) activation occurs rapidly (~1 min) after CCh treatment, 3 ) directly binds PLC- SH2 domains and associates dynamically with PLC- under elevated [Ca 2+ ] i conditions, and 4 ) does not directly bind NHE3. Under elevated [Ca 2+ ] i conditions, PLC- scaffolds c-Src into NHE3-containing multiprotein complexes before dissociation of PLC- from NHE3 and subsequent endocytosis of NHE3.
    Print ISSN: 0363-6143
    Electronic ISSN: 1522-1563
    Topics: Medicine
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  • 10
    Publication Date: 2013-08-02
    Description: We used mouse cortical collecting duct principal cells (mpkCCD c14 cell line) as a model to determine whether statins reduce the harmful effects of cyclosporine A (CsA) on the distal nephron. The data showed that treatment of cells with CsA increased transepithelial resistance and that the effect of CsA was abolished by lovastatin. Scanning ion conductance microscopy showed that CsA significantly increased the height of cellular protrusions near tight junctions. In contrast, lovastatin eliminated the protrusions and even caused a modest depression between cells. Western blot analysis and confocal microscopy showed that lovastatin also abolished CsA-induced elevation of both zonula occludens-1 and cholesterol in tight junctions. In contrast, a high concentration of CsA induced apoptosis, which was also attenuated by lovastatin, elevated intracellular ROS via activation of NADPH oxidase, and increased the expression of p47 phox . Sustained treatment of cells with lovastatin also induced significant apoptosis, which was attenuated by CsA, but did not elevate intracellular ROS. These results indicate that both CsA and lovastatin are harmful to principal cells of the distal tubule, but via ROS-dependent and ROS-independent apoptotic pathways, respectively, and that they counteract probably via mobilization of cellular cholesterol levels.
    Print ISSN: 1931-857X
    Electronic ISSN: 1522-1466
    Topics: Medicine
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