Munish Kumar - Academia.edu (original) (raw)

Papers by Munish Kumar

Research paper thumbnail of Application of high pressure–high temperature equation of state for elastic properties of solids

Physica B-condensed Matter, 2002

The theory of high pressure-high temperature equation of state recently developed is used to inve... more The theory of high pressure-high temperature equation of state recently developed is used to investigate the elastic properties of solids under the effect of temperature as well as pressure. The calculated values of temperature dependence of bulk modulus of NaCl are found to present a better agreement with the experimental data as compared with earlier relation. The results obtained for second-order elastic constants are found to present a good agreement with experimental data. It is concluded that the present approach is very simple and far better compared with the theory of lattice dynamics and two-body central potential. It makes the situation very simple and straightforward as compared with earlier investigations. The results are reported for NaCl, KCl, CaF 2 , MgO, CaO, Mg 2 SiO 4 and Al 2 O 3 . r

Research paper thumbnail of High pressure equation of state for solids

Physica B-condensed Matter, 1995

A useful general equation of state based on thermodynamic analysis is proposed to investigate the... more A useful general equation of state based on thermodynamic analysis is proposed to investigate the properties of solids under the effect of high pressures. It is shown that the Murnaghan equation of state widely used in the literature is a particular case of the proposed equation of state. ...

Research paper thumbnail of Temperature dependence of interatomic separation and bulk modulus for ionic solids

Physica B-condensed Matter, 1995

The temperature dependence of the interatomic separation and bulk modulus is investigated from ro... more The temperature dependence of the interatomic separation and bulk modulus is investigated from room temperature up to melting temperature for sixteen ionic solids. A phenomenological relation is derived to investigate the interatomic separations as a function of temperature. The results thus obtained are used to predict values of the bulk modulus at different temperatures. The results are compared with the available experimental data and are discussed in the view of recent research in the field of high temperature physics. A good agreement between theory and experiment demonstrates the validity of the present work.

Research paper thumbnail of Cardioprotective Role of Sodium Thiosulfate on Chronic Heart Failure by Modulating Endogenous H2S Generation

Pharmacology, 2008

Sodium thiosulfate (STS) has been shown to be an antioxidant and calcium solubilizer, but the pos... more Sodium thiosulfate (STS) has been shown to be an antioxidant and calcium solubilizer, but the possible role of STS in dysfunctional ventricles remains unknown. Here, we assessed the effects of STS in the failing heart. Heart failure was created by an arteriovenous fistula (AVF). Mice were divided into 4 groups: sham, AVF, sham + STS, and AVF + STS. STS (3 mg/ml) was supplemented with drinking water for 6 weeks in the appropriate surgery groups after surgery. M-mode echocardiograms showed ventricular contractile dysfunction with reduced aortic blood flow in AVF mice, whereas STS treatment prevented the decline in cardiac function. Ventricular collagen, MMP-2 and -9, and TIMP-1 were robustly increased with a decreasing trend in adenylate cyclase VI expression; however, STS supplementation reversed these effects in AVF mice. Among 2 enzymes that produce endogenous hydrogen sulfide (H(2)S), cystathionine-gamma-lyase (CSE) expression was attenuated in AVF mice with no changes in cystathionine-beta-synthase (CBS) expression. In addition, reduced production of H(2)S in AVF ventricular tissue was normalized with STS supplementation. Moreover, cardiac tissues were more responsive to H(2)S when AVF mice were supplemented with STS compared to AVF alone. These results suggested that STS modulated cardiac dysfunction and the extracellular matrix, in part, by increasing ventricular H(2)S generation.

Research paper thumbnail of H 2 S Protects Against Methionine–Induced Oxidative Stress in Brain Endothelial Cells

Antioxidants & Redox Signaling, 2009

Homocysteine (Hcy) causes cerebrovascular dysfunction by inducing oxidative stress. However, to d... more Homocysteine (Hcy) causes cerebrovascular dysfunction by inducing oxidative stress. However, to date, there are no strategies to prevent Hcy-induced oxidative damage. Hcy is an H 2 S precursor formed from methionine (Met) metabolism. We aimed to investigate whether H 2 S ameliorated Met-induced oxidative stress in mouse brain endothelial cells (bEnd3). The bEnd3 cells were exposed to Met treatment in the presence or absence of NaHS (donor of H 2 S). Met-induced cell toxicity increased the levels of free radicals in a concentration-dependent manner. Met increased NADPH-oxidase-4 (NOX-4) expression and mitigated thioredxion-1(Trx-1) expression. Pretreatment of bEnd3 with NaHS (0.05 mM) attenuated the production of free radicals in the presence of Met and protected the cells from oxidative damage. Furthermore, NaHS enhanced inhibitory effects of apocynin, N-acetyl-l-cysteine (NAC), reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), N -nitro-l-arginine methyl ester (L-NAME) on ROS production and redox enzymes levels induced by Met. In conclusion, the administration of H 2 S protected the cells from oxidative stress induced by hyperhomocysteinemia (HHcy), which suggested that NaHS/H 2 S may have therapeutic potential against Met-induced oxidative stress. Antioxid. Redox Signal. 11, 25-33.

Research paper thumbnail of MicroRNAs as a therapeutic target for cardiovascular diseases

Journal of Cellular and Molecular Medicine, 2009

• Introduction• Biogenesis of miRNAs and their regulatory mechanisms• MiRNAs in cardiovascular di... more • Introduction• Biogenesis of miRNAs and their regulatory mechanisms• MiRNAs in cardiovascular diseases• MiRNAs in hypertrophy• MiRNAs in cardiac fibrosis• MiRNAs in arrhythmia• MiRNAs in myocardial infarction• MiRNAs in heart failure• MiRNAs in angiogenesis• MiRNAs in cardiomyopathy• MiRNAs in antherogenesis• Role of Dicer in cardiomyopathy• MiRNAs - a new strategy for treatment of cardiovascular diseases- MiRNA – an innovative therapeutic approach- MiRNAs in stem cell therapy- A new candidate in microRNomics• Therapeutic challenges and their remedies- Mode of delivery of miRNAs- Role of microevironment• Approaches of miRNAs in cardiovascular therapy• Introduction• Biogenesis of miRNAs and their regulatory mechanisms• MiRNAs in cardiovascular diseases• MiRNAs in hypertrophy• MiRNAs in cardiac fibrosis• MiRNAs in arrhythmia• MiRNAs in myocardial infarction• MiRNAs in heart failure• MiRNAs in angiogenesis• MiRNAs in cardiomyopathy• MiRNAs in antherogenesis• Role of Dicer in cardiomyopathy• MiRNAs - a new strategy for treatment of cardiovascular diseases- MiRNA – an innovative therapeutic approach- MiRNAs in stem cell therapy- A new candidate in microRNomics• Therapeutic challenges and their remedies- Mode of delivery of miRNAs- Role of microevironment• Approaches of miRNAs in cardiovascular therapyIntroductionBiogenesis of miRNAs and their regulatory mechanismsMiRNAs in cardiovascular diseasesMiRNAs in hypertrophyMiRNAs in cardiac fibrosisMiRNAs in arrhythmiaMiRNAs in myocardial infarctionMiRNAs in heart failureMiRNAs in angiogenesisMiRNAs in cardiomyopathyMiRNAs in antherogenesisRole of Dicer in cardiomyopathyMiRNAs - a new strategy for treatment of cardiovascular diseases- MiRNA – an innovative therapeutic approach- MiRNAs in stem cell therapy- A new candidate in microRNomicsMiRNA – an innovative therapeutic approachMiRNAs in stem cell therapyA new candidate in microRNomicsTherapeutic challenges and their remedies- Mode of delivery of miRNAs- Role of microevironmentMode of delivery of miRNAsRole of microevironmentApproaches of miRNAs in cardiovascular therapyAbstractMicroRNAs (miRNAs) are tiny, endogenous, conserved, non-coding RNAs that negatively modulate gene expression by either promoting the degradation of mRNA or down-regulating the protein production by translational repression. They maintain optimal dose of cellular proteins and thus play a crucial role in the regulation of biological functions. Recent discovery of miRNAs in the heart and their differential expressions in pathological conditions provide glimpses of undiscovered regulatory mechanisms underlying cardiovascular diseases. Nearly 50 miRNAs are overexpressed in mouse heart. The implication of several miRNAs in cardiovascular diseases has been well documented such as miRNA-1 in arrhythmia, miRNA-29 in cardiac fibrosis, miRNA-126 in angiogenesis and miRNA-133 in cardiac hypertrophy. Aberrant expression of Dicer (an enzyme required for maturation of all miRNAs) during heart failure indicates its direct involvement in the regulation of cardiac diseases. MiRNAs and Dicer provide a particular layer of network of precise gene regulation in heart and vascular tissues in a spatiotemporal manner suggesting their implications as a powerful intervention tool for therapy. The combined strategy of manipulating miRNAs in stem cells for their target directed differentiation and optimizing the mode of delivery of miRNAs to the desired cells would determine the future potential of miRNAs to treat a disease. This review embodies the recent progress made in microRNomics of cardiovascular diseases and the future of miRNAs as a potential therapeutic target - the putative challenges and the approaches to deal with it.MicroRNAs (miRNAs) are tiny, endogenous, conserved, non-coding RNAs that negatively modulate gene expression by either promoting the degradation of mRNA or down-regulating the protein production by translational repression. They maintain optimal dose of cellular proteins and thus play a crucial role in the regulation of biological functions. Recent discovery of miRNAs in the heart and their differential expressions in pathological conditions provide glimpses of undiscovered regulatory mechanisms underlying cardiovascular diseases. Nearly 50 miRNAs are overexpressed in mouse heart. The implication of several miRNAs in cardiovascular diseases has been well documented such as miRNA-1 in arrhythmia, miRNA-29 in cardiac fibrosis, miRNA-126 in angiogenesis and miRNA-133 in cardiac hypertrophy. Aberrant expression of Dicer (an enzyme required for maturation of all miRNAs) during heart failure indicates its direct involvement in the regulation of cardiac diseases. MiRNAs and Dicer provide a particular layer of network of precise gene regulation in heart and vascular tissues in a spatiotemporal manner suggesting their implications as a powerful intervention tool for therapy. The combined strategy of manipulating miRNAs in stem cells for their target directed differentiation and optimizing the mode of delivery of miRNAs to the desired cells would determine the future potential of miRNAs to treat a disease. This review embodies the recent progress made in microRNomics of cardiovascular diseases and the future of miRNAs as a potential therapeutic target - the putative challenges and the approaches to deal with it.

Research paper thumbnail of Comparison of SPET brain perfusion and 18F-FDG brain metabolism in patients with chronic fatigue syndrome

Nuclear Medicine Communications, 1998

Chronic fatigue syndrome is a clinically defined condition of uncertain aetiology. We compared 99... more Chronic fatigue syndrome is a clinically defined condition of uncertain aetiology. We compared 99Tcm-HMPAO single photon emission tomography (SPET) brain perfusion with dual-head 18F-FDG brain metabolism in patients with chronic fatigue syndrome. Eighteen patients (14 females, 4 males), who fulfilled the diagnostic criteria of the Centers for Disease Control for chronic fatigue syndrome, were investigated. Thirteen patients had abnormal SPET brain perfusion scans and five had normal scans. Fifteen patients had normal glucose brain metabolism scans and three had abnormal scans. We conclude that, in chronic fatigue syndrome patients, there is discordance between SPET brain perfusion and 18F-FDG brain uptake. It is possible to have brain perfusion abnormalities without corresponding changes in glucose uptake.

Research paper thumbnail of SPET brain perfusion imaging in mild traumatic brain injury without loss of consciousness and normal computed tomography

Nuclear Medicine Communications, 1999

We present SPET brain perfusion findings in 32 patients who suffered mild traumatic brain injury ... more We present SPET brain perfusion findings in 32 patients who suffered mild traumatic brain injury without loss of consciousness and normal computed tomography. None of the patients had previous traumatic brain injury, CVA, HIV, psychiatric disorders or a history of alcohol or drug abuse. Their ages ranged from 11 to 61 years (mean = 42). The study was performed in 20 patients (62%) within 3 months of the date of injury and in 12 (38%) patients more than 3 months post-injury. Nineteen patients (60%) were involved in a motor vehicle accident, 10 patients (31%) sustained a fall and three patients (9%) received a blow to the head. The most common complaints were headaches in 26 patients (81%), memory deficits in 15 (47%), dizziness in 13 (41%) and sleep disorders in eight (25%). The studies were acquired approximately 2 h after an intravenous injection of 740 MBq (20.0 mCi) of 99Tcm-HMPAO. All images were acquired on a triple-headed gamma camera. The data were displayed on a 10-grade colour scale, with 2-pixel thickness (7.4 mm), and were reviewed blind to the patient's history of symptoms. The cerebellum was used as the reference site (100% maximum value). Any decrease in cerebral perfusion in the cortex or basal ganglia less than 70%, or less than 50% in the medial temporal lobe, compared to the cerebellar reference was considered abnormal. The results show that 13 (41%) had normal studies and 19 (59%) were abnormal (13 studies performed within 3 months of the date of injury and six studies performed more than 3 months post-injury). Analysis of the abnormal studies revealed that 17 showed 48 focal lesions and two showed diffuse supratentorial hypoperfusion (one from each of the early and delayed imaging groups). The 12 abnormal studies performed early had 37 focal lesions and averaged 3.1 lesions per patient, whereas there was a reduction to--an average of 2.2 lesions per patient in the five studies (total 11 lesions) performed more than 3 months post-injury. In the 17 abnormal studies with focal lesions, the following regions were involved in descending frequency: frontal lobes 58%, basal ganglia and thalami 47%, temporal lobes 26% and parietal lobes 16%. We conclude that: (1) SPET brain perfusion imaging is valuable and sensitive for the evaluation of cerebral perfusion changes following mild traumatic brain injury; (2) these changes can occur without loss of consciousness; (3) SPET brain perfusion imaging is more sensitive than computed tomography in detecting brain lesions; and (4) the changes may explain a neurological component of the patient's symptoms in the absence of morphological abnormalities using other imaging modalities.

Research paper thumbnail of Nitrotyrosinylation, remodeling and endothelial-myocyte uncoupling in iNOS, cystathionine beta synthase (CBS) knockouts and iNOS/CBS double knockout mice

Journal of Cellular Biochemistry, 2009

Increased levels of homocysteine (Hcy), recognized as hyperhomocysteinemia (HHcy), were associate... more Increased levels of homocysteine (Hcy), recognized as hyperhomocysteinemia (HHcy), were associated with cardiovascular diseases. There was controversy regarding the detrimental versus cardio protective role of inducible nitric oxide synthase (iNOS) in ischemic heart disease. The aim of this study was to test the hypothesis that the Hcy generated nitrotyrosine by inducing the endothelial nitric oxide synthase, causing endothelial-myocyte (E-M) coupling. To differentiate the role of iNOS versus constitutive nitric oxide synthase (eNOS and nNOS) in Hcy-mediated nitrotyrosine generation and matrix remodeling in cardiac dysfunction, left ventricular (LV) tissue was analyzed from cystathionine beta synthase (CBS) heterozygote knockout, iNOS homozygote knockout, CBS−/+/iNOS−/− double knockout, and wild-type (WT) mice. The levels of nitrotyrosine, MMP-2 and -9 (zymographic analysis), and fibrosis (by trichrome stain) were measured. The endothelial-myocyte function was determined in cardiac rings. In CBS−/+ mice, homocysteine was elevated and in iNOS−/− mice, nitric oxide was significantly reduced. The nitrotyrosine and matrix metalloproteinase-9 (MMP-9) levels were elevated in double knockout and CBS−/+ as compared to WT mice. Although MMP-2 levels were similar in CBS−/+, iNOS−/−, and CBS−/+/iNOS−/−, the levels were three- to fourfold higher than WT. The levels of collagen were similar in CBS−/+ and iNOS−/−, but they were threefold higher than WT. Interesting, the levels of collagen increased sixfold in double knockouts, compared to WT, suggesting synergism between high Hcy and lack of iNOS. Left ventricular hypertrophy was exaggerated in the iNOS−/− and double knockout, and mildly increased in the CBS−/+, compared to WT mice. The endothelial-dependent relaxation was attenuated to the same extent in the CBS−/+ and iNOS−/−, compared to WT, but it was robustly blunted in double knockouts. The results concluded that homocysteine generated nitrotyrosine in the vicinity of endothelium, caused MMP activation and endothelium-myocyte uncoupling. The generation of nitrotyrosine was independent of iNOS. J. Cell. Biochem. 106: 119–126, 2009. © 2008 Wiley-Liss, Inc.

Research paper thumbnail of Mitochondrial matrix metalloproteinase activation decreases myocyte contractility in hyperhomocysteinemia

American Journal of Physiology-heart and Circulatory Physiology, 2008

Cardiomyocyte N-methyl-d-aspartate receptor-1 (NMDA-R1) activation induces mitochondrial dysfunct... more Cardiomyocyte N-methyl-d-aspartate receptor-1 (NMDA-R1) activation induces mitochondrial dysfunction. Matrix metalloproteinase protease (MMP) induction is a negative regulator of mitochondrial function. Elevated levels of homocysteine [hyperhomocysteinemia (HHCY)] activate latent MMPs and causes myocardial contractile abnormalities. HHCY is associated with mitochondrial dysfunction. We tested the hypothesis that HHCY activates myocyte mitochondrial MMP (mtMMP), induces mitochondrial permeability transition (MPT), and causes contractile dysfunction by agonizing NMDA-R1. The C57BL/6J mice were administered homocystinemia (1.8 g/l) in drinking water to induce HHCY. NMDA-R1 expression was detected by Western blot and confocal microscopy. Localization of MMP-9 in the mitochondria was determined using confocal microscopy. Ultrastructural analysis of the isolated myocyte was determined by electron microscopy. Mitochondrial permeability was measured by a decrease in light absorbance at 540 nm using the spectrophotometer. The effect of MK-801 (NMDA-R1 inhibitor), GM-6001 (MMP inhibitor), and cyclosporine A (MPT inhibitor) on myocyte contractility and calcium transients was evaluated using the IonOptix video edge track detection system and fura 2-AM. Our results demonstrate that HHCY activated the mtMMP-9 and caused MPT by agonizing NMDA-R1. A significant decrease in percent cell shortening, maximal rate of contraction (-dL/dt), and maximal rate of relaxation (+dL/dt) was observed in HHCY. The decay of calcium transient amplitude was faster in the wild type compared with HHCY. Furthermore, the HHCY-induced decrease in percent cell shortening, -dL/dt, and +dL/dt was attenuated in the mice treated with MK-801, GM-6001, and cyclosporin A. We conclude that HHCY activates mtMMP-9 and induces MPT, leading to myocyte mechanical dysfunction by agonizing NMDA-R1.

Research paper thumbnail of Cystathionine -synthase gene transfer and 3-deazaadenosine ameliorate inflammatory response in endothelial cells

American Journal of Physiology-cell Physiology, 2007

Although elevated levels of homocysteine (Hcy) known as hyperhomocysteinemia (HHcy) are associate... more Although elevated levels of homocysteine (Hcy) known as hyperhomocysteinemia (HHcy) are associated with increased inflammation and vascular remodeling, the mechanism of Hcy-mediated inflammation and vascular remodeling is unclear. The matrix metalloproteinases (MMPs) and adhesion molecules play an important role in vascular remodeling. We hypothesized that HHcy induces inflammation by increasing adhesion molecules and matrix protein expression. Endothelial cells were supplemented with high methionine, and Hcy accumulation was measured by HPLC. Nitric oxide (NO) bioavailability was detected by a NO probe. The protein expression was measured by Western blot analysis. MMP-9 activity was detected by gelatin-gel zymography. We demonstrated that methionine supplement promoted upregulation of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) through increased Hcy accumulation. In addition, increased synthesis of collagen type-1 was also observed. MMP-9 gene expression and protein activity were increased in methionine supplement groups. 3-Deazaadenosine (DZA), an adenosine analogue, prevented high methionine-induced ICAM-1 and VCAM-1 expression and collagen type-1 synthesis. Transfection of endothelial cells with cystathionine-beta-synthase (CBS) gene construct, which converts Hcy to cystathionine, reduced Hcy accumulation in high methionine-fed cells. CBS gene transfection reduced the inflammatory response, as evident by attenuated ICAM-1 and VCAM-1 expression. Furthermore, collagen type-1 expression and MMP-9 activity were dramatically attenuated with CBS gene transfection. These results suggested that methionine supplement increased Hcy accumulation, which was associated with inflammatory response and matrix remodeling such as collagen type-1 synthesis and MMP-9 activity. However, in vitro DZA and CBS gene therapy successfully treated the HHcy-induced inflammatory reaction in the methionine metabolism pathway.

Research paper thumbnail of Application of high pressure–high temperature equation of state for elastic properties of solids

Physica B-condensed Matter, 2002

The theory of high pressure-high temperature equation of state recently developed is used to inve... more The theory of high pressure-high temperature equation of state recently developed is used to investigate the elastic properties of solids under the effect of temperature as well as pressure. The calculated values of temperature dependence of bulk modulus of NaCl are found to present a better agreement with the experimental data as compared with earlier relation. The results obtained for second-order elastic constants are found to present a good agreement with experimental data. It is concluded that the present approach is very simple and far better compared with the theory of lattice dynamics and two-body central potential. It makes the situation very simple and straightforward as compared with earlier investigations. The results are reported for NaCl, KCl, CaF 2 , MgO, CaO, Mg 2 SiO 4 and Al 2 O 3 . r

Research paper thumbnail of High pressure equation of state for solids

Physica B-condensed Matter, 1995

A useful general equation of state based on thermodynamic analysis is proposed to investigate the... more A useful general equation of state based on thermodynamic analysis is proposed to investigate the properties of solids under the effect of high pressures. It is shown that the Murnaghan equation of state widely used in the literature is a particular case of the proposed equation of state. ...

Research paper thumbnail of Temperature dependence of interatomic separation and bulk modulus for ionic solids

Physica B-condensed Matter, 1995

The temperature dependence of the interatomic separation and bulk modulus is investigated from ro... more The temperature dependence of the interatomic separation and bulk modulus is investigated from room temperature up to melting temperature for sixteen ionic solids. A phenomenological relation is derived to investigate the interatomic separations as a function of temperature. The results thus obtained are used to predict values of the bulk modulus at different temperatures. The results are compared with the available experimental data and are discussed in the view of recent research in the field of high temperature physics. A good agreement between theory and experiment demonstrates the validity of the present work.

Research paper thumbnail of Cardioprotective Role of Sodium Thiosulfate on Chronic Heart Failure by Modulating Endogenous H2S Generation

Pharmacology, 2008

Sodium thiosulfate (STS) has been shown to be an antioxidant and calcium solubilizer, but the pos... more Sodium thiosulfate (STS) has been shown to be an antioxidant and calcium solubilizer, but the possible role of STS in dysfunctional ventricles remains unknown. Here, we assessed the effects of STS in the failing heart. Heart failure was created by an arteriovenous fistula (AVF). Mice were divided into 4 groups: sham, AVF, sham + STS, and AVF + STS. STS (3 mg/ml) was supplemented with drinking water for 6 weeks in the appropriate surgery groups after surgery. M-mode echocardiograms showed ventricular contractile dysfunction with reduced aortic blood flow in AVF mice, whereas STS treatment prevented the decline in cardiac function. Ventricular collagen, MMP-2 and -9, and TIMP-1 were robustly increased with a decreasing trend in adenylate cyclase VI expression; however, STS supplementation reversed these effects in AVF mice. Among 2 enzymes that produce endogenous hydrogen sulfide (H(2)S), cystathionine-gamma-lyase (CSE) expression was attenuated in AVF mice with no changes in cystathionine-beta-synthase (CBS) expression. In addition, reduced production of H(2)S in AVF ventricular tissue was normalized with STS supplementation. Moreover, cardiac tissues were more responsive to H(2)S when AVF mice were supplemented with STS compared to AVF alone. These results suggested that STS modulated cardiac dysfunction and the extracellular matrix, in part, by increasing ventricular H(2)S generation.

Research paper thumbnail of H 2 S Protects Against Methionine–Induced Oxidative Stress in Brain Endothelial Cells

Antioxidants & Redox Signaling, 2009

Homocysteine (Hcy) causes cerebrovascular dysfunction by inducing oxidative stress. However, to d... more Homocysteine (Hcy) causes cerebrovascular dysfunction by inducing oxidative stress. However, to date, there are no strategies to prevent Hcy-induced oxidative damage. Hcy is an H 2 S precursor formed from methionine (Met) metabolism. We aimed to investigate whether H 2 S ameliorated Met-induced oxidative stress in mouse brain endothelial cells (bEnd3). The bEnd3 cells were exposed to Met treatment in the presence or absence of NaHS (donor of H 2 S). Met-induced cell toxicity increased the levels of free radicals in a concentration-dependent manner. Met increased NADPH-oxidase-4 (NOX-4) expression and mitigated thioredxion-1(Trx-1) expression. Pretreatment of bEnd3 with NaHS (0.05 mM) attenuated the production of free radicals in the presence of Met and protected the cells from oxidative damage. Furthermore, NaHS enhanced inhibitory effects of apocynin, N-acetyl-l-cysteine (NAC), reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), N -nitro-l-arginine methyl ester (L-NAME) on ROS production and redox enzymes levels induced by Met. In conclusion, the administration of H 2 S protected the cells from oxidative stress induced by hyperhomocysteinemia (HHcy), which suggested that NaHS/H 2 S may have therapeutic potential against Met-induced oxidative stress. Antioxid. Redox Signal. 11, 25-33.

Research paper thumbnail of MicroRNAs as a therapeutic target for cardiovascular diseases

Journal of Cellular and Molecular Medicine, 2009

• Introduction• Biogenesis of miRNAs and their regulatory mechanisms• MiRNAs in cardiovascular di... more • Introduction• Biogenesis of miRNAs and their regulatory mechanisms• MiRNAs in cardiovascular diseases• MiRNAs in hypertrophy• MiRNAs in cardiac fibrosis• MiRNAs in arrhythmia• MiRNAs in myocardial infarction• MiRNAs in heart failure• MiRNAs in angiogenesis• MiRNAs in cardiomyopathy• MiRNAs in antherogenesis• Role of Dicer in cardiomyopathy• MiRNAs - a new strategy for treatment of cardiovascular diseases- MiRNA – an innovative therapeutic approach- MiRNAs in stem cell therapy- A new candidate in microRNomics• Therapeutic challenges and their remedies- Mode of delivery of miRNAs- Role of microevironment• Approaches of miRNAs in cardiovascular therapy• Introduction• Biogenesis of miRNAs and their regulatory mechanisms• MiRNAs in cardiovascular diseases• MiRNAs in hypertrophy• MiRNAs in cardiac fibrosis• MiRNAs in arrhythmia• MiRNAs in myocardial infarction• MiRNAs in heart failure• MiRNAs in angiogenesis• MiRNAs in cardiomyopathy• MiRNAs in antherogenesis• Role of Dicer in cardiomyopathy• MiRNAs - a new strategy for treatment of cardiovascular diseases- MiRNA – an innovative therapeutic approach- MiRNAs in stem cell therapy- A new candidate in microRNomics• Therapeutic challenges and their remedies- Mode of delivery of miRNAs- Role of microevironment• Approaches of miRNAs in cardiovascular therapyIntroductionBiogenesis of miRNAs and their regulatory mechanismsMiRNAs in cardiovascular diseasesMiRNAs in hypertrophyMiRNAs in cardiac fibrosisMiRNAs in arrhythmiaMiRNAs in myocardial infarctionMiRNAs in heart failureMiRNAs in angiogenesisMiRNAs in cardiomyopathyMiRNAs in antherogenesisRole of Dicer in cardiomyopathyMiRNAs - a new strategy for treatment of cardiovascular diseases- MiRNA – an innovative therapeutic approach- MiRNAs in stem cell therapy- A new candidate in microRNomicsMiRNA – an innovative therapeutic approachMiRNAs in stem cell therapyA new candidate in microRNomicsTherapeutic challenges and their remedies- Mode of delivery of miRNAs- Role of microevironmentMode of delivery of miRNAsRole of microevironmentApproaches of miRNAs in cardiovascular therapyAbstractMicroRNAs (miRNAs) are tiny, endogenous, conserved, non-coding RNAs that negatively modulate gene expression by either promoting the degradation of mRNA or down-regulating the protein production by translational repression. They maintain optimal dose of cellular proteins and thus play a crucial role in the regulation of biological functions. Recent discovery of miRNAs in the heart and their differential expressions in pathological conditions provide glimpses of undiscovered regulatory mechanisms underlying cardiovascular diseases. Nearly 50 miRNAs are overexpressed in mouse heart. The implication of several miRNAs in cardiovascular diseases has been well documented such as miRNA-1 in arrhythmia, miRNA-29 in cardiac fibrosis, miRNA-126 in angiogenesis and miRNA-133 in cardiac hypertrophy. Aberrant expression of Dicer (an enzyme required for maturation of all miRNAs) during heart failure indicates its direct involvement in the regulation of cardiac diseases. MiRNAs and Dicer provide a particular layer of network of precise gene regulation in heart and vascular tissues in a spatiotemporal manner suggesting their implications as a powerful intervention tool for therapy. The combined strategy of manipulating miRNAs in stem cells for their target directed differentiation and optimizing the mode of delivery of miRNAs to the desired cells would determine the future potential of miRNAs to treat a disease. This review embodies the recent progress made in microRNomics of cardiovascular diseases and the future of miRNAs as a potential therapeutic target - the putative challenges and the approaches to deal with it.MicroRNAs (miRNAs) are tiny, endogenous, conserved, non-coding RNAs that negatively modulate gene expression by either promoting the degradation of mRNA or down-regulating the protein production by translational repression. They maintain optimal dose of cellular proteins and thus play a crucial role in the regulation of biological functions. Recent discovery of miRNAs in the heart and their differential expressions in pathological conditions provide glimpses of undiscovered regulatory mechanisms underlying cardiovascular diseases. Nearly 50 miRNAs are overexpressed in mouse heart. The implication of several miRNAs in cardiovascular diseases has been well documented such as miRNA-1 in arrhythmia, miRNA-29 in cardiac fibrosis, miRNA-126 in angiogenesis and miRNA-133 in cardiac hypertrophy. Aberrant expression of Dicer (an enzyme required for maturation of all miRNAs) during heart failure indicates its direct involvement in the regulation of cardiac diseases. MiRNAs and Dicer provide a particular layer of network of precise gene regulation in heart and vascular tissues in a spatiotemporal manner suggesting their implications as a powerful intervention tool for therapy. The combined strategy of manipulating miRNAs in stem cells for their target directed differentiation and optimizing the mode of delivery of miRNAs to the desired cells would determine the future potential of miRNAs to treat a disease. This review embodies the recent progress made in microRNomics of cardiovascular diseases and the future of miRNAs as a potential therapeutic target - the putative challenges and the approaches to deal with it.

Research paper thumbnail of Comparison of SPET brain perfusion and 18F-FDG brain metabolism in patients with chronic fatigue syndrome

Nuclear Medicine Communications, 1998

Chronic fatigue syndrome is a clinically defined condition of uncertain aetiology. We compared 99... more Chronic fatigue syndrome is a clinically defined condition of uncertain aetiology. We compared 99Tcm-HMPAO single photon emission tomography (SPET) brain perfusion with dual-head 18F-FDG brain metabolism in patients with chronic fatigue syndrome. Eighteen patients (14 females, 4 males), who fulfilled the diagnostic criteria of the Centers for Disease Control for chronic fatigue syndrome, were investigated. Thirteen patients had abnormal SPET brain perfusion scans and five had normal scans. Fifteen patients had normal glucose brain metabolism scans and three had abnormal scans. We conclude that, in chronic fatigue syndrome patients, there is discordance between SPET brain perfusion and 18F-FDG brain uptake. It is possible to have brain perfusion abnormalities without corresponding changes in glucose uptake.

Research paper thumbnail of SPET brain perfusion imaging in mild traumatic brain injury without loss of consciousness and normal computed tomography

Nuclear Medicine Communications, 1999

We present SPET brain perfusion findings in 32 patients who suffered mild traumatic brain injury ... more We present SPET brain perfusion findings in 32 patients who suffered mild traumatic brain injury without loss of consciousness and normal computed tomography. None of the patients had previous traumatic brain injury, CVA, HIV, psychiatric disorders or a history of alcohol or drug abuse. Their ages ranged from 11 to 61 years (mean = 42). The study was performed in 20 patients (62%) within 3 months of the date of injury and in 12 (38%) patients more than 3 months post-injury. Nineteen patients (60%) were involved in a motor vehicle accident, 10 patients (31%) sustained a fall and three patients (9%) received a blow to the head. The most common complaints were headaches in 26 patients (81%), memory deficits in 15 (47%), dizziness in 13 (41%) and sleep disorders in eight (25%). The studies were acquired approximately 2 h after an intravenous injection of 740 MBq (20.0 mCi) of 99Tcm-HMPAO. All images were acquired on a triple-headed gamma camera. The data were displayed on a 10-grade colour scale, with 2-pixel thickness (7.4 mm), and were reviewed blind to the patient's history of symptoms. The cerebellum was used as the reference site (100% maximum value). Any decrease in cerebral perfusion in the cortex or basal ganglia less than 70%, or less than 50% in the medial temporal lobe, compared to the cerebellar reference was considered abnormal. The results show that 13 (41%) had normal studies and 19 (59%) were abnormal (13 studies performed within 3 months of the date of injury and six studies performed more than 3 months post-injury). Analysis of the abnormal studies revealed that 17 showed 48 focal lesions and two showed diffuse supratentorial hypoperfusion (one from each of the early and delayed imaging groups). The 12 abnormal studies performed early had 37 focal lesions and averaged 3.1 lesions per patient, whereas there was a reduction to--an average of 2.2 lesions per patient in the five studies (total 11 lesions) performed more than 3 months post-injury. In the 17 abnormal studies with focal lesions, the following regions were involved in descending frequency: frontal lobes 58%, basal ganglia and thalami 47%, temporal lobes 26% and parietal lobes 16%. We conclude that: (1) SPET brain perfusion imaging is valuable and sensitive for the evaluation of cerebral perfusion changes following mild traumatic brain injury; (2) these changes can occur without loss of consciousness; (3) SPET brain perfusion imaging is more sensitive than computed tomography in detecting brain lesions; and (4) the changes may explain a neurological component of the patient's symptoms in the absence of morphological abnormalities using other imaging modalities.

Research paper thumbnail of Nitrotyrosinylation, remodeling and endothelial-myocyte uncoupling in iNOS, cystathionine beta synthase (CBS) knockouts and iNOS/CBS double knockout mice

Journal of Cellular Biochemistry, 2009

Increased levels of homocysteine (Hcy), recognized as hyperhomocysteinemia (HHcy), were associate... more Increased levels of homocysteine (Hcy), recognized as hyperhomocysteinemia (HHcy), were associated with cardiovascular diseases. There was controversy regarding the detrimental versus cardio protective role of inducible nitric oxide synthase (iNOS) in ischemic heart disease. The aim of this study was to test the hypothesis that the Hcy generated nitrotyrosine by inducing the endothelial nitric oxide synthase, causing endothelial-myocyte (E-M) coupling. To differentiate the role of iNOS versus constitutive nitric oxide synthase (eNOS and nNOS) in Hcy-mediated nitrotyrosine generation and matrix remodeling in cardiac dysfunction, left ventricular (LV) tissue was analyzed from cystathionine beta synthase (CBS) heterozygote knockout, iNOS homozygote knockout, CBS−/+/iNOS−/− double knockout, and wild-type (WT) mice. The levels of nitrotyrosine, MMP-2 and -9 (zymographic analysis), and fibrosis (by trichrome stain) were measured. The endothelial-myocyte function was determined in cardiac rings. In CBS−/+ mice, homocysteine was elevated and in iNOS−/− mice, nitric oxide was significantly reduced. The nitrotyrosine and matrix metalloproteinase-9 (MMP-9) levels were elevated in double knockout and CBS−/+ as compared to WT mice. Although MMP-2 levels were similar in CBS−/+, iNOS−/−, and CBS−/+/iNOS−/−, the levels were three- to fourfold higher than WT. The levels of collagen were similar in CBS−/+ and iNOS−/−, but they were threefold higher than WT. Interesting, the levels of collagen increased sixfold in double knockouts, compared to WT, suggesting synergism between high Hcy and lack of iNOS. Left ventricular hypertrophy was exaggerated in the iNOS−/− and double knockout, and mildly increased in the CBS−/+, compared to WT mice. The endothelial-dependent relaxation was attenuated to the same extent in the CBS−/+ and iNOS−/−, compared to WT, but it was robustly blunted in double knockouts. The results concluded that homocysteine generated nitrotyrosine in the vicinity of endothelium, caused MMP activation and endothelium-myocyte uncoupling. The generation of nitrotyrosine was independent of iNOS. J. Cell. Biochem. 106: 119–126, 2009. © 2008 Wiley-Liss, Inc.

Research paper thumbnail of Mitochondrial matrix metalloproteinase activation decreases myocyte contractility in hyperhomocysteinemia

American Journal of Physiology-heart and Circulatory Physiology, 2008

Cardiomyocyte N-methyl-d-aspartate receptor-1 (NMDA-R1) activation induces mitochondrial dysfunct... more Cardiomyocyte N-methyl-d-aspartate receptor-1 (NMDA-R1) activation induces mitochondrial dysfunction. Matrix metalloproteinase protease (MMP) induction is a negative regulator of mitochondrial function. Elevated levels of homocysteine [hyperhomocysteinemia (HHCY)] activate latent MMPs and causes myocardial contractile abnormalities. HHCY is associated with mitochondrial dysfunction. We tested the hypothesis that HHCY activates myocyte mitochondrial MMP (mtMMP), induces mitochondrial permeability transition (MPT), and causes contractile dysfunction by agonizing NMDA-R1. The C57BL/6J mice were administered homocystinemia (1.8 g/l) in drinking water to induce HHCY. NMDA-R1 expression was detected by Western blot and confocal microscopy. Localization of MMP-9 in the mitochondria was determined using confocal microscopy. Ultrastructural analysis of the isolated myocyte was determined by electron microscopy. Mitochondrial permeability was measured by a decrease in light absorbance at 540 nm using the spectrophotometer. The effect of MK-801 (NMDA-R1 inhibitor), GM-6001 (MMP inhibitor), and cyclosporine A (MPT inhibitor) on myocyte contractility and calcium transients was evaluated using the IonOptix video edge track detection system and fura 2-AM. Our results demonstrate that HHCY activated the mtMMP-9 and caused MPT by agonizing NMDA-R1. A significant decrease in percent cell shortening, maximal rate of contraction (-dL/dt), and maximal rate of relaxation (+dL/dt) was observed in HHCY. The decay of calcium transient amplitude was faster in the wild type compared with HHCY. Furthermore, the HHCY-induced decrease in percent cell shortening, -dL/dt, and +dL/dt was attenuated in the mice treated with MK-801, GM-6001, and cyclosporin A. We conclude that HHCY activates mtMMP-9 and induces MPT, leading to myocyte mechanical dysfunction by agonizing NMDA-R1.

Research paper thumbnail of Cystathionine -synthase gene transfer and 3-deazaadenosine ameliorate inflammatory response in endothelial cells

American Journal of Physiology-cell Physiology, 2007

Although elevated levels of homocysteine (Hcy) known as hyperhomocysteinemia (HHcy) are associate... more Although elevated levels of homocysteine (Hcy) known as hyperhomocysteinemia (HHcy) are associated with increased inflammation and vascular remodeling, the mechanism of Hcy-mediated inflammation and vascular remodeling is unclear. The matrix metalloproteinases (MMPs) and adhesion molecules play an important role in vascular remodeling. We hypothesized that HHcy induces inflammation by increasing adhesion molecules and matrix protein expression. Endothelial cells were supplemented with high methionine, and Hcy accumulation was measured by HPLC. Nitric oxide (NO) bioavailability was detected by a NO probe. The protein expression was measured by Western blot analysis. MMP-9 activity was detected by gelatin-gel zymography. We demonstrated that methionine supplement promoted upregulation of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) through increased Hcy accumulation. In addition, increased synthesis of collagen type-1 was also observed. MMP-9 gene expression and protein activity were increased in methionine supplement groups. 3-Deazaadenosine (DZA), an adenosine analogue, prevented high methionine-induced ICAM-1 and VCAM-1 expression and collagen type-1 synthesis. Transfection of endothelial cells with cystathionine-beta-synthase (CBS) gene construct, which converts Hcy to cystathionine, reduced Hcy accumulation in high methionine-fed cells. CBS gene transfection reduced the inflammatory response, as evident by attenuated ICAM-1 and VCAM-1 expression. Furthermore, collagen type-1 expression and MMP-9 activity were dramatically attenuated with CBS gene transfection. These results suggested that methionine supplement increased Hcy accumulation, which was associated with inflammatory response and matrix remodeling such as collagen type-1 synthesis and MMP-9 activity. However, in vitro DZA and CBS gene therapy successfully treated the HHcy-induced inflammatory reaction in the methionine metabolism pathway.