bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of glycogen phosphorylase by the malin‐laforin complex
Authors: Dukhande Vikas V , Bridges Travis M , Gentry Matthew S 
Published: June 2021

Autosomal recessive mutations in genes encoding malin or laforin cause Lafora disease (LD), a progressive myoclonic epilepsy. Pathological aberrant glycogen accumulations in brain and various other organs are a hallmark of LD. Our group identified laforin as a novel glycogen phosphatase essential for maintaining glycogen in a soluble form. Malin is a RING‐type E3 ubiquitin ligase. Malin is known to ubiquitinate proteins involved in glycogen metabolism such as laforin, glycogen synthase, protein targeting to glycogen and glycogen debranching enzyme. However, except laforin, expression of these proteins is unchanged in malin knockout mice and thus malin's role in LD pathogenesis is still unclear. Glycogen phosphorylase and glycogen debranching enzyme are vital in catabolism of cellular glycogen. In this study, we aimed to discover substrate/s of malin and its function in LD pathogenesis. We employed immunoprecipitation, western analysis, immunocytochemistry and enzyme activity measurements. Our data uncovered glycogen phosphorylase as a novel substrate of malin. The expression of glycogen phosphorylase was decreased in liver and skeletal muscle tissues from malin knockout mice and glycogen phosphorylase expression was unchanged in tissues from laforin knockout mice. Similarly, overexpression of LD mutations of malin in HEK‐293 cells decreased glycogen phosphorylase expression. In addition, transient overexpression of malin in HEK‐ 293 cells increased the endogenous expression of glycogen phosphorylase. Taken together, our results have identified a novel substrate of malin. Further exploration into the mechanisms of this regulation will unravel insights in glycogen metabolism, physiological functions of malin‐laforin complex and will aid in betterment of LD pharmacotherapy.Supported by NIH grants R00NS061803, R01NS070899 and University of Kentucky College of Medicine startup funds.
Downregulation of the α2‐isoform of the Na,K‐pump inhibits EDHF‐like responses in rat mesenteric small arteries
Authors: Aalkjaer Christian , Nielsen Nina Moeller , Matchkov Vladimir 
Published: June 2021

Oubain is known to inhibit vascular relaxation mediated by EDHF. Since oubain acts on several isoforms of the Na,K‐pump and can activate a signaling cascade in addition to inhibit ion‐translocation we investigated whether downregulation of the α2‐isoform of the Na,K‐pump affects the EDHF‐like response.The α2‐isoform of the Na,K‐pump was downregulated with siRNA in rat mesenteric small arteries and the functional effect assessed by isometric myography in arteries constricted with norepinephrine in a concentration providing 80–90% of maximal tone. Downregulation was confirmed at the RNA and protein levelThere was no difference in relaxation to acetylcholine between the downregulated and control arteries (maximal relaxation 71±10 and 80±15%, n=7, respectively). After inhibition of NOS and COX less relaxation was seen in downregulated arteries compared to control (36±11 and 78±16%, n=7, respectively, p<0.05). Addition of TRAM34 and apamin fully inhibited this relaxation (6±4 and 4±4%, respectively).The study demonstrated the importance of the α2‐isoform of the Na,K‐pump for relaxation via EDHF and strongly indicates that the effects of oubain on EDHF is mediated via this isoform of the Na,K‐pump.
Small skeletal muscle veins exhibit substantial myogenic response, which is mediated by hydrogen peroxide‐induced activation of TP receptors
Authors: Debreczeni Béla Zoltán , Gara Edit , Veresh Zoltán , Tamás Róbert , Hamar János , Koller Ákos 
Published: June 2021

We hypothesized that isolated small veins (similarly arterioles) develop an appreciable myogenic tone in response to elevation of intraluminal pressure and aimed to elucidate the constrictor mechanism(s) involved. Thus small veins were isolated from gracilis muscle of male Wistar rats, then cannulated and incubated in the presence of 10 mmHg of intraluminal pressure at T = 37°C in a special pressure myograph chamber. Isolated small veins developed a substantial myogenic tone in response to increases in intraluminal pressure (from 1 to 12 mmHg). Calculated maximum myogenic tone was 70 ( 5 % of PD at 10 mmHg. Presence of indomethacin or catalase or SQ 29,548 reduced significantly the pressure‐induced myogenic tone. Also, H2O2 (10‐9‐10‐5 M) elicited concentration dependent constrictions, which were inhibited by the indomethacin or SQ 29,548. Arachidonic acid (10‐7–10‐4M) elicited concentration dependent constrictions, which were inhibited by indomethacin or SQ 29,548. In conclusion, in isolated small veins, 1) increases in pressure and H2O2 elicit substantial constrictons, both of which are inhibited by catalase, indomethacin or SQ 29,548 suggesting that the myogenic mechanism is mediated by H2O2 ‐induced arachidonic acid derived constrictor metabolite(s) such as prostaglandin H2/thromboxane A2 acting on TP receptors.Support: AHA Founders Aff. 0855910D and Hungarian Sci. Res. Funds, OTKA‐T48376.
The effect of network pattern alterations on microvascular resistance in hypertension
Authors: Yang Ming , Murfee Walter Lee 
Published: June 2021

Microvascular rarefaction, defined by a loss of vessels, is a common characteristic of hypertension and has been linked to elevated microvascular resistance. The objectives of this study were to determine whether rarefaction is associated with other network pattern alterations in hypertensive rat mesenteric networks and to whether these alterations lead to increased resistance. Mesenteric tissues from age‐matched (15–16 weeks) male spontaneously hypertensive rats (SHR) and normotensive Wistar‐ Kyoto (WKY) rats were harvested and labeled for PECAM, an endothelial cell marker. SHR networks displayed decreased microvascular area, arteriolar‐venular (AV) length, the number of AV branches, capillary segments and increased AV connections per network compared to WKY networks. Based on segment lengths, branching locations, and an assumed pressure drop of 65 mmHg, resistance per network was calculated using a computational model. For simulations with uniform vessel diameter and with the diameters based on reported intravital measurements, SHR resistance was not elevated compared to WKY level. Our results suggest that microvascular pattern alterations associated with hypertension are more complex than vessel loss and that rarefaction is not necessarily associated with elevated microvascular resistance. Supported by the Tulane Hypertension and Renal Center of Excellence.Grant Funding Source: Tulane Hypertension and Renal Center of Excellence.
IL‐6 Deletion Does Not Alter LV Remodeling and Dysfunction in Pressure Overload
Authors: Lai N. Chin , Tang Eric , Pandey Amit , Gao Meihua , Tang Tong 
Published: June 2021

Chronic pressure overload, as seen in persistent hypertension, is a major risk factor for congestive heart failure. Left ventricular (LV) dysfunction in the pressure‐overloaded heart is associated with increased cardiac IL‐6 expression. Chronic IL‐6 infusion also leads to LV dysfunction, indicating a causal effect of IL‐6 on cardiac function deterioration. In this study, we tested the hypothesis that IL‐6 deletion would be beneficial to the pressure‐overloaded heart. Transverse aortic constriction was performed with a 27ga needle on IL‐6‐deleted (IL6KO) mice and C57BL/6J mice (CON) to induce pressure overload. Both the hearts from CON and IL6KO mice showed decreased LV contractile function 2 and 4 weeks after pressure overload, which also induced an increased in LV end‐diastolic diameter and LV wall thickness. No group differences were found in LV hypertrophy and re‐activation of the fetal gene program. There were also no differences between CON and IL6KO mice in LV fibrosis or expression of extracellular matrix proteins after pressure overload. In addition, no group differences in apoptosis or autophagy were observed.ConclusionThese data indicate that IL‐6 deletion does not affect LV hypertrophy, dysfunction, or fibrosis in the setting of pressure overload. Reduction of molecular signaling elicited by proinflammatory IL‐6 family members, rather than the sole decrease of IL‐6 (such as immunodepletion with IL‐6 antibody), may be required to block deterioration of cardiac function in pressure overload.
Role of Ecto‐5′–nucleotidase (CD73) in the Development of Renal Fibrosis
Authors: Carota Isabel , Höcherl Klaus , Castrop Hayo 
Published: June 2021

Adenosine has been shown to be involved in the progression of fibrotic remodeling in various organs including the kidney. In the present study, ecto‐5′‐nucleotidase (CD73)‐deficient mice were used to address the route of adenosine generation during the development of renal fibrosis.To induce renal fibrosis, CD73+/+ and −/− mice were subjected to unilateral ureter obstruction (UUO) for 7 days (n=6 each). UUO induced renal fibrosis in both genotypes, and this was accompanied by a marked increase in CD73 protein abundance in WT mice (196±35% of the contralateral kidney, p=.026). Compared to WT mice, UUO kidneys from CD73−/− showed significantly lower mRNA and protein levels of fibrotic markers like alpha‐SMA, fibronectin, TGF‐beta, Ki67, MMP‐2, MMP‐13, MMP‐14, and of the collagens Col 1a1, Col 1a2, Col 3a1 and Col 4a3, as determined by qRT‐PCR, western blotting (p<.01 for WT vs. KO, each), and immunohistochemistry. F4/80 antigen staining revealed a massive infiltration of macrophages/monocytes in the cortex of fibrotic WT kidneys, whereas only scattered cells were observed in kidneys from CD73−/− mice. In summary, CD73 is induced in the UUO model, and CD73‐dependent extracellular generation of adenosine appears to promote the development of renal fibrosis. Consequently, CD73 may constitute a pharmacologic target for the management of renal fibrosis.
Nek1 regulation of VHL and cilia
Authors: Patil Mallikarjun , Pabla navajotsingh , Dong Zheng 
Published: June 2021

Nek1 is a member of NIMA related kinases in mammals that has been known to regulate ciliogenesis. Loss of function mutation in Nek1 leads to polycystic kidney disease in mouse and renal cysts in humans. pVHL, a well known tumor suppressor, has been recently implicated in the regulation of cilia and cell cycle. Loss of VHL function leads to renal cystic disease and renal cell carcinoma. Since mutation of Nek1 and VHL results in similar phenotype, we investigated if Nek1 and pVHL might function in a common regulatory pathway. Our in vitro and in vivo experiments show that pVHL may be a substrate of Nek1. Phosphorylation of VHL by Nek1 may affect the stability of pVHL and cilia dynamics. Phosphorylation site mutations in pVHL results in higher stability. Cells expressing mutant pVHL have stable cilia, resistant to serum stimulation and Nocodazole treatment. Phosphorylation of VHL by Nek1 does not seem to affect hypoxia inducible factors (HIF). Together, the results reveal a novel regulation of pVHL by Nek1, which may contributes to the regulation of cilia.This study was supported by NIH
Wall stress initiates the nuclear export and degradation of phosphorylated myocardin in vascular smooth muscle cells
Authors: Pfisterer Larissa , Feldner Anja , Hecker Markus , Korff Thomas 
Published: June 2021

Myocardin controls the expression of genes stabilizing the contractile phenotype of vascular smooth muscle cells (SMC) by binding to the CArG box of serum response factor. Despite its crucial role in the development of the embryonic vasculature, its impact on the phenotype of adult SMCs still is poorly understood. We observed a significant decrease in myocardin abundance in SMCs of mouse arteries upon in vivo exposure to increased wall stress (e.g. hypertension), accompanied by downregulation of target genes such as calponin and an increase in proliferation. In SMCs of isolated mouse arteries myocardin level strongly decreased upon a supraphysiological increase in transmural pressure. Subsequent analyses of human cultured SMCs exposed to enhanced stretch, suggested that this biomechanical force elicits the nuclear export of phosphorylated myocardin. Followed by its proteasomal degradation in the cytoplasm.These findings suggest that increased wall stress triggers the nuclear export of myocardin and its proteasomal degradation in arterial SMCs through an as yet unknown mechanism. This process may determine the switch towards the synthetic phenotype and thus control the onset of arterial remodeling.
Atherogenic Index of Plasma: A significant indicator for the onset of Atherosclerosis During Menopause in Hypertensive Females of Southeast Nigeria
Authors: Igweh John Chukwuka 
Published: June 2021

SUMMARY BACKGROUNDHypertension and menopause are independent risk factors for dyslipidaemia. In normotensive subjects, menopause causes significant alteration in lipid levels that may require medical intervention. It is thus expected that this alteration will become more relevant in hypertensive menopausal subjects. In our environment, diverse dietary, socioeconomic, and geographical variables might alter the expected pattern of deraignment.AIMS AND OBJECTIVESThis study aims to compare the total lipid profile and its subfractions in hypertensive premopausal and hypertensive postmenopausal subjects.MATERIALS AND METHODSThis is a comparative, cross sectional cohort study involving 116 hypertensive females (67 premenopausal and 49 postmenopausal) consecutively recruited over a two year period. Serum total cholesterol and its sub fractions, high density lipoprotein (HDL), low density lipoprotein (LDL), Very low density lipoprotein (VLDL), and triglyceride, (TG) were estimated using standardized enzymatic and mathematical methods. Significant differences were analysed with student T –test using SPSS version 11 computer software.RESULTSThere were no statistically significant differences in total cholesterol, HDL, LDL, VLDL and HDL/LDL ratio between the two groups (P> 0.05). However there were statistically significant differences in triglycerides and the atherogenic index of plasma (P<0.05).CONCLUSIONSimultaneous occurrence of menopause and hypertension leads to alteration in lipid profile that favours the use of triglyceride based indices (instead of HDL/LDL ratio) in determining the risk of developing atherosclerosis.
Progression of microalbuminuria in SHR is associated with diminished expression of proteins that belong to the receptor‐mediated endocytosis macromolecular complex
Authors: Inoue Bruna Hitomi , Machado Marcos Oporini , Girardi Adriana C 
Published: June 2021

Microalbuminuria is recognized to be a risk factor for cardiovascular and kidney disease and is associated with morbidity and mortality in hypertensive patients. It arises as a consequence of increased glomerular permeability and/or reduced tubular reabsorption. The aims of the present study were: (1) to analyze the temporal evolution and the pattern of urinary protein excretion in spontaneously hypertensive rats (SHR), and (2) to evaluate whether the expression of proteins implicated in receptor‐mediated endocytosis in the renal proximal tubule of SHR can vary with blood pressure. Urinary protein excretion was evaluated in 6, 14 and 21 week‐old SHR and in Wistar rats of corresponding age. Daily urinary protein excretion increased with the development of hypertension in SHR (15 ± 1; 71 ± 2 and 112 ± 6 mg/day at 6, 14 and 21 weeks respectively), but remained unchanged in normotensive rats. SDS‐PAGE analysis of urinary proteins showed that SHR displayed a progressive increase of intact urinary albumin excretion with age. Progression of microalbuminuria highly correlated with elevation of arterial blood pressure in SHR (0.91; P<0.0001). Moreover, during the period of 6 to 21 weeks of age, SHR only excreted proteins of the size of albumin or smaller. The expression of the endocytic receptors megalin and cubilin, the B2‐subunit of the H+‐ATPase and the ClC‐5 chloride channel decreased as blood pressure increased in SHR but remained unaltered in Wistar rats. Furthermore, western blot analysis of urine samples revealed that the urinary excretion of transferrin, a protein known to be reabsorbed via receptor mediated endocytosis, increases as blood pressure increases in SHR. Taken together these data suggest that SHR displays tubular proteinuria after development of hypertension at least in part due to a decrease of some components of the receptor‐mediated endocytosis macromolecular complex.Support: FAPESP
ER stress inhibition reduces cardiac damage and improves endothelial function in hypertensive mice
Authors: Kassan Modar Omar , Galan Maria , Partyka Megan , Henrion Daniel , Trebak Mohamed , Matrougui Khalid 
Published: June 2021

Vascular complications and cardiac damage are major cause of mortality in hypertension. In this study we explored the beneficial effect of ER stress inhibition on vascular and cardiac damage in hypertensionMice were infused with Ang‐II with or without ER stress inhibitors (Tudca and PBA) for 2 weeks Mice infused with Ang‐II displayed an increase in SBP, cardiac hypertrophy and fibrosis associated with enhanced collagenI content, TGFb activity and ER stress markers which were blunted by ER stress inhibitors. AngII induced hypertension increased ER stress in aorta and mesenteric resistance arteries (MRA) enhanced TGFb activity in aorta but not in RA, reduced eNOS phosphorylation and endothelium‐dependent relaxation (EDR) in aorta and MRA. ER stress inhibition reduced TGFb fnactivity, enhanced eNOS phosphorylation and EDR. TGFb pathway inhibition improved EDR in aorta while the reduction in ROS levels ameliorated EDR in MRA onlyER stress inhibition reduces cardiac damage and improves vascular function in Ang II‐induced hypertension. ER stress could be a potential target for cardiovascular therapy
Model of pulmonary hypertension induced by reversible pressure‐overloaded left heart failure in rats
Authors: Chovanec Milan , Herget Jan 
Published: June 2021

We focused on pulmonary hypertension induced by left heart failure in rats caused by inserting a polyethylene cannula into the ascending aorta via the left carotid artery.In experiment A, an obturating cannula was implanted for 1 week (group 1wk, n=7), for 3 weeks (group 3wks, n=6) and for 3 weeks with a 3 weeks recovery period after removal of the cannula (group 3+3wks, n=8). We measured RV/LV+S ratio. We found no difference in heart weight vs. controls in the 1wk and 3+3wks groups. The RV/LV+S ratio (0.39±0.024 vs. 0.27±0.008; p<0.01) was significantly increased in the group 3+3wks compared to controls. In experiment B, we measured pulmonary artery pressure (PAP) in closed‐chest animals. Group N (n=8) were normoxic controls. Group H (n=8) were hypoxic controls. Rats were exposed to normobaric hypoxia (10% O2) for 3 weeks. Mean PAP was significantly elevated in groups 1wk and 3wks compared to normoxic controls (25.0±1.18mmHg and 22.9±0.66mmHg vs. 16.9±0.97mmHg; p<0.01 and p<0.05 respectively) but significantly lower compared to hypoxic controls (25.0±1.18mmHg and 22.9±0.66mmHg vs. 33.4±2.0mmHg; p<0.001 and p<0.0001 respectively).This is a simple, well tolerated and fully reversible method of inducing pressure‐overloaded left heart failure followed by the significant pulmonary hypertension.Supported by: GACR 305/05/08/108, GAUK 78007 and Cardiovascular Research Centre 1M510.
Role of ENaC and of the Na/K pump on the Hypertonicity‐induced inhibition of Na Transport in Cystic Fibrosis Human Bronchial Epithelial Cells
Authors: Rasgado-Flores Hector , Ngansop Thierry , Piennette Paul , Gallegos Kevin , Bridges Robert J 
Published: June 2021

IntroductionHypertonic saline (HS) inhalation produces surprisingly long lasting benefits to Cystic Fibrosis (CF) patients. We have found that exposure to hypertonic challenge (HC) solutions produce long‐lasting inhibitions of the transepithelial short‐circuit current (ISC) in primary cultures of human bronchial epithelial (HBE) cells from CF donors.AimsTo determine if the HS‐induced inhibition of ISC is due to inhibition of the epithelial Na+ channels (ENaC) and/or the basolateral Na/K ATPase.MethodsHBE cells from CF were grown on Transwell inserts (air liquid interface) and were mounted on Ussing chambers to perform trans‐epithelial impedance analysis and measure transepithelial ISC, resistance (Rt), capacitance (Ct) and Conductance (Gt) The putative role of ENaC and of the Na/ATPase on the HC‐induced inhibition of the ISC was studied by permeabilizing the apical or basolateral membranes with Nystatin.Resultsi) Exposure to apical or basolateral HC‐NaCl or HC‐mannitol inhibited ISC. ii) Exposure to HC‐solutions induced cell shrinkage as indicated by a reduction in CT.; iii) Neither activity of the Na/K ATPase nor the ENaC was absolutely required for the HC‐induced inhibition of ISC.ConclusionsCell shrinkage, together with a likely increase in the intracellular Na+ concentration inhibit transepithelial Na transport (ISC). Both, the ENaC and the Na/K ATPase play a role in this inhibition.
Discovery of novel small molecule CFTR inhibitor through structural modification of compound from Thai plant: Mechanism and Anti‐diarrheal efficacy
Authors: Sawasvirojwong Sutthipong , Suksamrarn Sunit , Chatsudthipong Varanuj , Muanprasat Chatchai 
Published: June 2021

Inhibition of Cystic fibrosis transmembrane conductance regulator (CFTR) is proposed as a promising therapeutic approach for cholera, one of the important health problems worldwide. To identify novel class of CFTR inhibitors, several natural compounds were structurally modified and tested for CFTR inhibitory effect in Fisher rat thyroid (FRT) cells stably expressing human CFTR. Among test compounds, compound 130 exhibited the highest potency (IC50 ~10 μM). It inhibited CFTR‐mediated apical chloride current stimulated by forskolin, CPT‐cAMP and apigenin. CFTR inhibitory effect of compound 130 was reversible and not associated with cytotoxicity. Electrophysiological analysis indicated that compound 130 is a CFTR pore blocker. Similarly, compound 130 inhibited cAMP and cholera toxin‐induced chloride secretion across T84 cell monolayers without changing intracellular cAMP level. Interestingly, compound 130 inhibited calcium‐activated chloride channel with similar potency. Intraluminal injection of compound 130 blocked cholera toxin‐induced intestinal fluid secretion by ~80% in mouse closed‐loop models. In mouse open‐loop cholera models, oral administration of compound 130 prevented intestinal fluid secretion was by ~80%. This study reveals a new class of CFTR inhibitors, which holds the promise for treatment of infectious secretory diarrhea.This work was supported by the Thailand Research Fund and the Office of the Higher Education Commission and Mahidol University under the National Research Universities Initiative.
Acute inflammation alters the response to stretch in mouse extensor digitorum longus muscle afferents
Authors: Wilkinson Katherine A. , Hochman Shawn 
Published: June 2021

Inflammatory pain alters muscle spindle responses to stretch (Wenngren, et al, 1998; Ro & Capra, 2001), but the exact mechanism of sensitization is unknown. We used an in vitro mouse hindlimb muscle‐nerve preparation to study plasticity in afferent responses to ramp and hold stretches following acute inflammation (0.5 mg/kg lipopolysaccharide (LPS) 18 hrs before experiment). Following LPS, units had lower baseline firing and more units were only active during stretch (6/16 LPS vs. 3/26 control). The LPS units also displayed a significantly greater decrease in firing frequency over the 4 s stretch. Some LPS units (3/16) are likely group III/IV instead of muscle spindle afferents; they had very small responses to stretch and did not show the characteristic frequency adaptation. Overall, the acute systemic inflammatory state induced by LPS clearly alters the response profile of muscle afferents to stretch, and therefore proprioceptive signaling. Further study on these changes are planned to provide insight into underlying mechanisms, their behavioral relevance, and to identify strategies that normalize function.Supported by K12 GM000680 NIH/NIGMS More Division (KAW) and Pfizer (SH).