Nonresponse to Acute Vasodilator Challenge and Prognosis in Heart Failure With Pulmonary Hypertension.

BACKGROUND: An acute vasodilator challenge is recommended in patients with heart failure and pulmonary hypertension during heart transplant evaluation. The aim of the study was to assess which hemodynamic parameters are associated with nonresponsiveness to the challenge. METHODS AND RESULTS: This study is a retrospective analysis of 402 patients with heart failure with pulmonary hypertension who underwent right heart catheterization and a pulmonary vasodilator challenge. Among the 140 who fulfilled the transplant guidelines eligibility criteria for the vasodilator challenge, 38 were responders and 102 nonresponders. At multivariable analysis, a diastolic blood pressure of <70 mm Hg, pulmonary vascular resistance of >5 Woods units, and pulmonary artery compliance of <1.2 mL/mm Hg were independently associated with poor response to vasodilator challenge (all P < .001). The presence of any 2 of these 3 conditions was associated with a 90% probability of being a nonresponder. The covariate-adjusted hemodynamic predictors of death in the entire population were a low baseline systolic blood pressure (P = .0017) and a low baseline right ventricular stroke work index (P = .0395). CONCLUSIONS: In patients with heart failure and pulmonary hypertension, low pulmonary arterial compliance, high pulmonary vascular resistance, and low diastolic blood pressure predict the nonresponsiveness to acute vasodilator challenge whilst a poor right ventricular function predicts a dismal prognosis.

Pulmonary Artery Wedge Pressure Respiratory Variation Increases With Sodium Nitroprusside Vasodilator Challenge.

BACKGROUND: The physiologic factors leading to pulmonary arterial wedge pressure respiratory variation (PAWPvar) are underexplored. We hypothesized that PAWPvar is associated with baseline PAWP and would predict response to sodium nitroprusside (SNP). METHODS AND RESULTS: We performed a retrospective study of right heart catheterization studies in 51 subjects with SNP challenge at our institution from 2012 to 2019. PAWPvar was defined as expiratory minus inspiratory PAWP. Baseline %PAWPvar was inversely correlated with baseline PAWP (R = -0.5). SNP administration led to increased %PAWPvar (+27%, P < .01). Subjects with low baseline PAWPvar (less than the median) had an increase in PAWPvar with SNP (3 ± 4 mm Hg), whereas those with a high baseline PAWPvar (greater than the median) did not (-0.6 ± 4 mm Hg, P = .003). Those who had a greater than the median PAWPvar increase with SNP had greater cardiac output augmentation compared with those who had less than a median increase in PAWPvar (1.7 ± 1.5 L/min vs 0.9 ± 0.7 L/min, P = .02). An increasing PAWPvar after SNP was associated with significant discrepancy in the number of subjects achieving transplant-acceptable pulmonary vascular resistance (<2.5 Wood units) when calculated by expiratory versus mean PAWP (37 vs 27 subjects, 20% discrepancy rate). Subjects with a higher PAWPvar after SNP were more likely to demonstrate discrepant transplant-acceptable pulmonary vascular resistance calculations comparing expiratory versus mean PAWP than those with lower PAWPvar post-SNP (47% vs 13%, odds ratio 5.5, P = .03). CONCLUSIONS: Our findings indicate that PAWPvar is a meaningful physiologic parameter that is influenced by the compliance of the left heart/pulmonary vascular system and its relative preload and afterload states.

Role of Klotho in migration and proliferation of human dermal microvascular endothelial cells.

PURPOSE: To examine the possible role of Klotho (Kl) in human microvasculature. METHODS: The expression level of Kl in primary human dermal microvascular endothelial cells (HDMECs) and primary human dermal fibroblasts (HFb) was detected by real-time polymerase chain reaction amplification (qRT-PCR), Western blot analyses and immunohistochemistry. Migration of HDMECs and HFb was examined in monolayer wound healing "scratch assay" and Transwell assay. Proliferation of these cells was examined using Cell Proliferation BrdU incorporation assay. RESULTS: Our results have shown that downregulation of Kl abrogated HDMECs migration after 48h. On the other hand, migration of HFb significantly increased after blocking Kl. Lack of Kl decreased expression of genes involved in the activation of endothelial cells and enhanced expression of genes involved in extracellular matrix remodeling and organization of connective tissue. CONCLUSIONS: This study for the first time provides the evidence that Kl is expressed in HDMECs and HFb. Additionally, we have demonstrated that Kl is implicated in the process of angiogenesis of human dermal microvasculature.

mTOR Complexes Repress Hypertrophic Agonist-Stimulated Expression of Connective Tissue Growth Factor in Adult Cardiac Muscle Cells.

Connective tissue growth factor (CTGF) is a fibrogenic cytokine that promotes fibrosis in various organs. In the heart, both cardiomyocytes (CM) and cardiac fibroblasts have been reported as a source of CTGF expression, aiding cardiac fibrosis. Although the mammalian target of rapamycin (mTOR) forms 2 distinct complexes, mTORC1 and mTORC2, and plays a central role in integrating biochemical signals for protein synthesis and cellular homeostasis, we explored its role in CTGF expression in adult feline CM. CM were stimulated with 10 µM phenylephrine (PE), 200 nM angiotensin (Ang), or 100 nM insulin for 24 hours. PE and Ang, but not insulin, caused an increase in CTGF mRNA expression with the highest expression observed with PE. Inhibition of mTOR with torin1 but not rapamycin significantly enhanced PE-stimulated CTGF expression. Furthermore, silencing of raptor and rictor using shRNA adenoviral vectors to suppress mTORC1 and mTORC2, respectively, or blocking phosphatidylinositol 3-kinase (PI3K) signaling with LY294002 (LY) or Akt signaling by dominant-negative Akt expression caused a substantial increase in PE-stimulated CTGF expression as measured by both mRNA and secreted protein levels. However, studies with dominant-negative delta isoform of protein kinase C demonstrate that delta isoform of protein kinase C is required for both agonist-induced CTGF expression and mTORC2/Akt-mediated CTGF suppression. Finally, PE-stimulated CTGF expression was accompanied with a corresponding increase in Smad3 phosphorylation and pretreatment of cells with SIS3, a Smad3 specific inhibitor, partially blocked the PE-stimulated CTGF expression. Therefore, a PI3K/mTOR/Akt axis plays a suppressive role on agonist-stimulated CTGF expression where the loss of this mechanism could be a contributing factor for the onset of cardiac fibrosis in the hypertrophying myocardium.

A Kinase-Independent Function of c-Src Mediates p130Cas Phosphorylation at the Serine-639 Site in Pressure Overloaded Myocardium.

Early work in pressure overloaded (PO) myocardium shows that integrins mediate focal adhesion complex formation by recruiting the adaptor protein p130Cas (Cas) and nonreceptor tyrosine kinase c-Src. To explore c-Src role in Cas-associated changes during PO, we used a feline right ventricular in vivo PO model and a three-dimensional (3D) collagen-embedded adult cardiomyocyte in vitro model that utilizes a Gly-Arg-Gly-Asp-Ser (RGD) peptide for integrin stimulation. Cas showed slow electrophoretic mobility (band-shifting), recruitment to the cytoskeleton, and tyrosine phosphorylation at 165, 249, and 410 sites in both 48 h PO myocardium and 1 h RGD-stimulated cardiomyocytes. Adenoviral mediated expression of kinase inactive (negative) c-Src mutant with intact scaffold domains (KN-Src) in cardiomyocytes did not block the RGD stimulated changes in Cas. Furthermore, expression of KN-Src or kinase active c-Src mutant with intact scaffold function (A-Src) in two-dimensionally (2D) cultured cardiomyocytes was sufficient to cause Cas band-shifting, although tyrosine phosphorylation required A-Src. These data indicate that c-Src's adaptor function, but not its kinase function, is required for a serine/threonine specific phosphorylation(s) responsible for Cas band-shifting. To explore this possibility, Chinese hamster ovary cells that stably express Cas were infected with either ß-gal or KN-Src adenoviruses and used for Cas immunoprecipitation combined with mass spectrometry analysis. In the KN-Src expressing cells, Cas showed phosphorylation at the serine-639 (human numbering) site. A polyclonal antibody raised against phospho-serine-639 detected Cas phosphorylation in 24-48 h PO myocardium. Our studies indicate that c-Src's adaptor function mediates serine-639 phosphorylation of Cas during integrin activation in PO myocardium.

Age-associated alterations of lipofuscin, membrane-bound ATPases and intracellular calcium in cortex, striatum and hippocampus of rat brain: protective role of glutathione monoester.

Brain aging has become an area of intense research and a subject of much speculation fueled largely from the widely recognized fact that age is the biggest risk factor in most neurodegenerative diseases and age-related increase of reactive oxygen species is particularly detrimental to postmitotic tissues. In the present study, we have evaluated the possible role of glutathione monoester (GME), when administered intraperitoneally (12mg/kg body weight) for 20 days on age-associated changes in the levels of lipofuscin, Na+K+, Mg2+, Ca2+ ATPase activities and intracellular calcium levels in discrete brain regions of young and aged male albino Wistar rats. An age-associated increase in lipofuscin, intracellular calcium in cortex, striatum and hippocampus was observed and contradictorily, a decrease in the activities of membrane-bound enzyme activities was also observed. Supplementation of GME brought these changes to near normalcy. Thus, GME improves neuronal antioxidant status, thereby effectively attenuating any putative increase in oxidative stress with age.

Oxidative stress and DNA single strand breaks in skeletal muscle of aged rats: role of carnitine and lipoicacid.

The exposure of biological system to various conditions of oxidative stress is the major contributor for aging process. Oxidative stress in turn increases the cellular levels of oxidatively modified proteins, lipids and nucleic acids resulting in a loss of physical activity and metabolic integrity. In this study, we evaluated the role of L-carnitine and DL-alpha-lipoic acid in minimizing oxidant generation and macromolecular damage in skeletal muscle of aged rats. We found that the oxidant generation was increased in aged rat skeletal muscle when compared to young rats. There was a simultaneous increase in the levels of lipid peroxidation, protein carbonyl content and DNA strand breaks in aged rat skeletal muscle. Administration of L-carnitine (300 mg/kg body wt/day) and DL-alpha-lipoic acid (100 mg/kg body wt/day) to aged rats for 30 days, decreased the oxidant generation, lipid peroxidation, protein carbonylation and DNA strand breaks. We concluded that co-administration of carnitine and lipoic acid to aged rats has the potential to prevent oxidative stress mediated macromolecular damage in skeletal muscle of aged rats by their putative role as efficient antioxidants.

REMOVED: l-Carnitine and alpha-lipoic acid improves mitochondrial function during ageing process.

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Age-associated deficit of mitochondrial oxidative phosphorylation in skeletal muscle: role of carnitine and lipoic acid.

Mitochondrial damage has implicated a major contributor for ageing process. In the present study, we measured mitochondrial membrane swelling, mitochondrial respiration (state 3 and 4) by using oxygen electrode in skeletal muscle of young (3-4 months old) and aged rats (above 24 months old) with supplementation of L: -carnitine and DL: -alpha-lipoic acid. Our results shows that the mitochondrial membrane swelling and state 4 respiration were increased more in skeletal muscle mitochondria of aged rats than in young control rats, whereas the state 3 respiration, respiratory control ratio (RCR) and ADP:O ratio decreased more in aged rats than in young rats. After supplementation of carnitine and lipoic acid to aged rats for 30 days, the state 3 respiration and RCR were increased, whereas the state 4 and mitochondrial membrane swelling were decreased to near normal rats. From our results, we conclude that combined supplementation of carnitine and lipoic acids to aged rats increases the skeletal muscle mitochondrial respiration, thereby increasing the level of ATP.