Hanumanth Reddy - Academia.edu (original) (raw)

Papers by Hanumanth Reddy

Journal of Cellular Biochemistry, 1996

Extracellular matrix metalloproteinases (MMPs) are activated in dilated cardiomyopathic (DCM) hea... more Extracellular matrix metalloproteinases (MMPs) are activated in dilated cardiomyopathic (DCM) hearts [Tyagi et al. (1996): Mol Cell Biochem 155:13-21]. To examine whether the MMP activation is occurring at the gene expression level, we performed differential display mRNA analysis on tissue from six dilated cardiomyopathy (DCM) explanted and five normal human hearts. Specifically, we identified three genes to be induced and several other genes to be repressed following DCM. Southern blot analysis of isolated cDNA using a collagenase cDNA probe indicated that one of the genes induced during DCM was interstitial collagenase (MMP-1). Northern blot analysis using MMP-1 cDNA probe indicated that MMP-1 was induced three- to fourfold in the DCM heart as compared to normal tissue. To analyze posttranslational expression of MMP and tissue inhibitor of matrix metalloproteinase (TIMP) we performed immunoblot, immunoassay, and substrate zymographic assays. TIMP-1 and MMP-1 levels were 37 +/- 8 ng/mg and 9 +/- 2 ng/mg in normal tissue specimens (P < 0.01) and 2 +/- 1 ng/mg and 45 +/- 11 ng/mg in DCM tissue (P < 0.01), respectively. Zymographic analysis demonstrated lytic bands at 66 kDa and 54 kDa in DCM tissue as compared to one band at 66 kDa in normal tissue. Incubation of zymographic gel with metal chelator (phenanthroline) abolished both bands suggesting activation of neutral MMP in DCM heart tissue. TIMP-1 was repressed approximately twentyfold in DCM hearts when compared with normal heart tissue. In situ immunolabeling of MMP-1 indicated phenotypic differences in the fibroblast cells isolated from the DCM heart as compared to normal heart. These results suggest disruption in the balance of myopathic-fibroblast cell ECM-proteinase and antiproteinase in ECM remodeling which is followed by dilated cardiomyopathy.

Echocardiography-a Journal of Cardiovascular Ultrasound and Allied Techniques, 2003

Journal of Molecular and Cellular Cardiology, 1996

Human heart matrix metalloproteinases (MMP) are present in the latent form and activated in the f... more Human heart matrix metalloproteinases (MMP) are present in the latent form and activated in the failing heart. To examine whether the MMP activation was due to gene and/or post-translational modification, we analysed tissue from 10 explanted hearts due to coronary heart disease (CHD) and five normal left atrial tissue from donor hearts. Based on in situ immunolabeling MMP-1, tissue inhibitor of metalloproteinase (TIMP-1) and collagen were co-localized in the interstitial tissue. Based on sandwich ELISA, TIMP-1 and MMP-1 levels were 37 +/- 8 ng/mg and 9 +/- 2 ng/mg in normal tissue (P < 0.01) and 12 +/- 5 ng/mg and 75 +/- 11 ng/mg in the infarcted tissue (P < 0.01), respectively. These levels suggest repression of TIMP-1 during myocardial infarction. Northern blot analysis indicated that the mRNAs for both MMP-1 and TIMP-1 were increased three-to four-fold in the infarcted tissue as compared to the normal tissue, suggesting upregulation of MMP and TIMP gene transcription following infarction. Based on in situ tissue overlay zymography, the generalized activation of MMP was observed in the interstitium of the infarcted heart. Zymographic and immunoblot analysis demonstrated the presence of one band at 66 kDa (MMP-2) in the normal tissue and several bands at 92 (MMP-9), 66 (MMP-2) and 54 kDa (MMP-1) in the infarcted heart. Incubation of the zymographic gel with metal chelator (phenanthroline) abolished bands at 92 kDa and 54 kDa but phenanthroline did not abolish the lytic band at 66 kDa. The 66 kDa band was completely abolished in the presence of phenanthroline and phenyl methyl sulfonyl fluoride (PMSF). 2D-zymographic analysis suggested that the lytic band at 66 kDa was a mixture of two neutral proteinases with different isoelectric point. Plasminogen/gelatin zymographic analysis of infarcted tissue extract indicated that the band at 66 kDa was plasmin generated due to increased expression of tissue plasminogen activator (tPA) activity. In relation to increased expression of gelatinase in the infarcted tissue, our data suggest that gelatinase B (92 kDa) is induced in diseased heart. The results suggest that tPA converts plasminogen to plasmin which, in turn, activates MMPs and inactivates TIMP-1 post-translationally following ischemic cardiomyopathy.

Echocardiography-a Journal of Cardiovascular Ultrasound and Allied Techniques, 2007

Background: Aortic valve sclerosis, without stenosis, has been associated with an increased cardi... more Background: Aortic valve sclerosis, without stenosis, has been associated with an increased cardiovascular mortality and morbidity due to myocardial infarction. However, it is unclear whether it is a cardiovascular risk factor or a cardiac disease marker. The goal of our study is to evaluate the difference in the prevalence of cardiovascular disease and risk factors among patients with or without aortic sclerosis. Methods: This observational study compared a group of 142 consecutive subjects with aortic valve sclerosis, assigned as group S, with a group of 101 subjects without aortic sclerosis, assigned as group C. Patients with bicuspid aortic valves and those with antegrade Doppler velocity across aortic valve leaflets exceeding 2.0 m/sec were excluded. Results: Mean ages of groups S and C were 71 ± 8, and 68.8 ± 6 years, respectively (P value = not significant). The prevalence of smoking, diabetes, hypercholesterolemia, hypertension, pulse pressure, left ventricular diastolic dysfunction, atrial fibrillation, and stroke was not significantly different between the two groups. However, there was a significantly higher prevalence of left ventricular hypertrophy (P = 0.05), ventricular arrhythmias (P = 0.02), myocardial infarction (P = 0.04), and systolic heart failure (P = 0.04) in aortic sclerosis group. Conclusions: Aortic sclerosis is associated with a higher prevalence of left ventricular hypertrophy, ventricular arrhythmias, myocardial infarction, and systolic heart failure, while the prevalence of cardiovascular risk factors is not different between aortic sclerosis patients and controls. Hence, aortic sclerosis represents a cardiac disease marker useful for early identification of high-risk patients beyond cardiovascular risk factors rate.

Atherosclerosis, 1995

To understand the balance of proteinase antiproteinase activity and the production of extracellul... more To understand the balance of proteinase antiproteinase activity and the production of extracellular matrix (ECM) at the site of arterial injury, we analyzed the composition of ECM and proteinase activity in normal internal mammary arteries, tissue samples obtained from atherosclerotic coronary lesions and restenotic lesions obtained during directional coronary atherectomy. Histologically and biochemically, collagen and proteoglycans increased, and elastin decreased in samples from restenotic lesions when compared to samples taken from patients undergoing their first revascularization (de novo). In contrast, cellularity was increased in samples obtained from de novo patients as compared to samples obtained from restenotic lesions. Intrinsic activity of matrix metalloproteinases (MMPs) was measured by using zymography and scanning all the lytic bands in zymographic gel. In these gels, identical amounts of total protein were loaded in each lane. MMP activity was determined as % of the total (latent and active) MMPs after trypsin activation (100%) in the normal artery. Intrinsic MMP activity was reduced to 6% +/- 1% in atherosclerotic lesions and 1% +/- 1% in restenotic lesions, when compared to activity found in normal (10% +/- 3%) arteries. Based on solubilization of fluorescein-conjugated elastin by the extracts, the MMP-mediated elastinolytic activity was 0.2 +/- 0.1, 8.8 +/- 1.5, and 24.0 +/- 3 nmol/min/mg in restenotic, native atherosclerotic and normal tissue, respectively. The results suggested that, in arterial tissue from patients with angiographic restenosis, there is an increased production of ECM collagen and a decrease in MMP activity compared to both normal artery and atherosclerotic samples from de novo patients undergoing an initial revascularization procedure of a significant coronary artery lesion.

Chronic hyperglycemia and hypercholesterolemia have been shown to alter ionic currents in vascula... more Chronic hyperglycemia and hypercholesterolemia have been shown to alter ionic currents in vascular smooth muscle. We tested the hypothesis that the combined effect of hyperglycemia and hyperlipidemia (diabetic dyslipidemia) would increase the Ca 2ϩ -sensitive K ϩ (KCa) current as a compensatory response to an increase in intracellular Ca 2ϩ concentration. We also hypothesized that exercise training would prevent this elevation in K Ca current. Miniature Yucatan swine were randomly assigned to five groups: control, standard pig chow (C, n ϭ 6); hyperlipidemic, high-fat pig chow (H, n ϭ 5); diabetic, standard pig chow (D, n ϭ 7); diabetic, high-fat pig chow ("diabetic dyslipidemic," DD, n ϭ 12); and exercise-trained DD (DDX, n ϭ 9). High-fat chow consisted of standard minipig chow supplemented with cholesterol (2%) and coconut oil. Increased coronary vasoconstriction assessed in vivo and in vitro in DD was prevented by exercise. Patch-clamp experiments performed on right coronary artery smooth muscle cells resulted in greater K ϩ current densities in the H, D, and DD groups vs. the DDX group between Ϫ10 and 40 mV. In fura 2-loaded cells, current activated by caffeine-induced Ca 2ϩ release was greater in H, D, and DD compared with C and DDX (P Ͻ 0.05), whereas intracellular Ca 2ϩ concentration was not different across groups. Finally, there were no differences in the K Ca or Kv channel protein content between groups. These data indicate that hyperglycemia, hyperlipidemia, and diabetic dyslipidemia lead to elevated whole cell K ϩ current and increased functional coupling of KCa and Ca 2ϩ release. Endurance exercise prevented increased coupling of Ca 2ϩ release to KCa channel activation in diabetic dyslipidemia.

Journal of The American College of Cardiology, 1991

Journal of Molecular and Cellular Cardiology, 2001

Journal of Molecular and Cellular Cardiology, Volume 33, Issue 6, Pages A112, June 2001, Authors:... more Journal of Molecular and Cellular Cardiology, Volume 33, Issue 6, Pages A112, June 2001, Authors:Karan D. Singh; Ashwani Bedi; Darla B. Hess; Christina Eberhard; Greg C. Flaker; Jack Curtis; Hanumanth K. Reddy. ...

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Journal of Cardiovascular Pharmacology and Therapeutics, 2004

The standard treatment for right heart failure includes aggressive fluid resuscitation, inotropic... more The standard treatment for right heart failure includes aggressive fluid resuscitation, inotropic agents, and avoiding drugs, such as diuretics or nitrates, or maneuvers that decrease pre-load. Even an increase in vagal tone caused by the insertion of a bladder catheter can acutely decrease preload and lead to cardiogenic shock. Other modalities include early reperfusion therapy and pacemaker implantation for complete heart block or loss of atrioventricular synchrony. Acute right heart failure carries a very high mortality because of the limited options available for its management. Among newer treatments, inhaled nitric oxide and intravenous vasopressin have shown promise for acute right ventricular failure.

Molecular and Cellular Biochemistry, 1996

In the normal myocardium matrix metalloproteinases (MMP) are present in the latent form. To exami... more In the normal myocardium matrix metalloproteinases (MMP) are present in the latent form. To examine whether MMP are activated following infarction or idiopathic dilated cardiomyopathy (DCM), we extracted and measured MMP activity in tissue derived from 7 explanted, failing human hearts due to either previous myocardial infarction (MI) or DCM. MMP activity in infarcted left ventricle (LV), noninfarcted IV and right ventricle (RV) from MI patients, as well as tissue from either ventricle of DCM patients, were compared to the activity of donor heart tissue. SDS-PAGE and dye-binding assays were used to determine total protein concentration, while collagenase activity was measured by SDS-PAGE type substrate gels embedded with type I gelatin (zymography). Accuracy of the zymographic technique was shown for tissue samples as small as 0.05 mg and was comparable to results obtained by a spectrophotometric method.. After normalization for total protein concentration, we found 3 ± 1 % collagenase activity in normal atrial tissue which could be activated to 80–90% by trypsin or plasmin, indicating that collagenase is normally inactive or in a latent form in human heart. In endo- and epimyocardium of infarcted LV on the other hand, collagenase activity was 85–95% and 10–20%, respectively, while 5–10% and 3–5%, respectively, in noninfarcted LV In DCM, collagenolytic activity in the endo and epimyocardium was 75 ± 5 and 35 ± 5% in the LV and 35 ± 7 and 20 ± 5% in the RV, respectively. Thus, in dilated failing human hearts secondary to previous MI or DCM, MMP activity is increased. This is particularly the case within the endomyocardium of the infarcted and noninfarcted portions of either ventricle with MI and in both ventricles in DCM. This suggests that an activation of collagenase throughout the myocardium may contribute to its remodeling that includes ventricular dilatation and wall thinning.

Journal of Hypertension, 1992

To examine the inter-relationship between effector hormones of the renin-angiotensin-aldosterone ... more To examine the inter-relationship between effector hormones of the renin-angiotensin-aldosterone system and fibrosis, a determinant of abnormal myocardial stiffness, and to determine whether pharmacological interference with these hormones can prevent or regress this pathological structural remodeling. Two morphological expressions of myocardial fibrosis are evident, a perivascular and interstitial fibrosis, not related to cardiac myocyte necrosis, and microscopic scarring that replaces lost myocytes. The former, a reactive fibrosis, is related to elevations in circulating mineralocorticoids (aldosterone or deoxycorticosterone) with increased dietary sodium, and not to arterial hypertension or ventricular loading. Scarring follows the cytotoxicity associated with elevated plasma angiotensin II levels and the increased K+ excretion that accompanies chronic mineralocorticoid excess. Given the association of these hormones with fibrosis, the concept of cardioprotection was evaluated in various prevention trials. Reactive fibrosis was prevented in unilateral renal ischaemia by angiotensin converting enzyme (ACE) inhibition with captopril and in either primary or secondary hyperaldosteronism by antagonism of the aldosterone receptor with spironolactone. Scarring (and cell loss) was prevented in renal ischemia by captopril and by K(+)-sparing diuretics (spironolactone, amiloride) in primary hyperaldosteronism. In treatment trials, where reactive fibrosis was established, lisinopril promoted regression of the fibrosis and therefore was cardioprotective. Myocardial fibrosis is related to chronic mineralocorticoid excess (with increased dietary sodium), angiotensin II and increased K+ excretion. Cardioprotective and cardioreparative strategies that respectively prevent or regress the development of fibrous tissue have been demonstrated in experimental models and now merit clinical evaluation.

Journal of Cardiovascular Pharmacology and Therapeutics, 2006

and association with a porcine gammaherpesvirus allogeneic hematopoietic cell transplantation: si... more and association with a porcine gammaherpesvirus allogeneic hematopoietic cell transplantation: similarity to human PTLD Posttransplantation lymphoproliferative disease in miniature swine after http://bloodjournal.hematologylibrary.org/content/97/5/1467.full.html Updated information and services can be found at: (1882 articles) Transplantation (4217 articles) Neoplasia

Molecular and Cellular Biochemistry, 2005

Background: Idiopathic dilated cardiomyopathy (DCM), ventricular systolic dysfunction and chamber... more Background: Idiopathic dilated cardiomyopathy (DCM), ventricular systolic dysfunction and chamber dilatation are accompanied by architectural remodeling, wall thinning and cardiac myocyte slippage. Recent work has demonstrated an association between collagen degradation and an increased expression of matrix metalloproteinases (MMPs). Accordingly, we have sought to correlate (a) collagen degradation with MMP elevations and, (b) assay the neutralizing potential of a known inhibitor of MMP, tetracycline on MMPs in DCM. Methods: Assessment of LV volume and shape by 2-D echocardiography was performed. Light microscopic assessment of histopathology in picrosirius red stained biopsy samples of 11 DCM patients and six post-transplant patients was performed. Zymographic estimation of MMP activity and influence of tetracycline on MMP activity was assessed. Results: Small amount of interstitial collagen was noted in the control group, whereas in the DCM hearts, chamber dilatation was associated with areas of scanty myocyte necrosis, islands of excess collagen, and focal areas of absent or scanty collagen with intact myocytes. In cardiomyopathic tissue, collagenase activity was markedly elevated at 63% compared with 8% in post-transplant tissue. Tetracycline at a concentration of 285 ± 10 μM (IC50) inhibited collagenase activity by 50% in cardiomyopathic tissue. Conclusions: Areas of focal interstitial collagen accumulation were accompanied by collagen fiber lysis and increased collagenase activity in dilated cardiomyopathy. This enhanced collagenolytic activity found in endomyocardial biopsy tissue was inhibited by tetracycline. The non-antibiotic property of tetracycline may be of potential value in the prevention of ventricular dilatation in idiopathic dilated cardiomyopathy. (Mol Cell Biochem 264: 183–191, 2004)

Journal of Interventional Cardiology, 2002

The human circulation to the human myocardium is unique in multiple ways. There is a great need f... more The human circulation to the human myocardium is unique in multiple ways. There is a great need for oxygenated blood supply to the myocardial muscle. The heart mainly operates on aerobic metabolism. Since the coronary arterial oxygen extraction is at near maximal level (coronary sinus oxygen saturation 25-35%),' myocardial blood flow and oxygenation are critically dependent on coronary vasodilator reserve. Coronary flow reserve (CFR) is defined as the maximal extent of coronary flow relative to the baseline flow elicited by a potent pharmacological stimulus. CFR is a ratio of maximally elicited coronary flow to resting flow. It is 2-5 in humans and 4-7 in experimental animals. Coronary flow stimulators include transient coronary occlusion, angiographic contrast, intracoronary nitroglycerin, adenosine, bradykinin, and papaverine. CFR represents the maximal vasodilator capacity of the total coronary vascular bed largely comprising of the microvascular network and conduit epicardial vessels. CFR is inversely proportional to coronary microvascular resistance if the conduit vessels are normal. Coronary vascular resistance is coronary perfusion pressure divided by basis for assessing critical coronary stenosis. Instantaneous flow response and regional distribution during coronary hyperemia as measures of coronary flow reserve. Am J Cardiol 1974;33:87-94. Pinch C, Schwaiger M. The clinical role of positron emission tomography in management of the cardiac patient. Rev Port Cardiol2ooO. l9(Suppl. 1):189-I 100. Donohue TJ, Kern MJ. Aguirre FV, et al. Assessing the hemodynamic significance of coronary artery stenoses: Analysis of translesional pressure-flow velocity relations in patients. J Am

Journal of Cardiopulmonary Rehabilitation, 1988

Echocardiography-a Journal of Cardiovascular Ultrasound and Allied Techniques, 2004

Background: Coronary artery remodeling is a structural change in the vessel wall and typically in... more Background: Coronary artery remodeling is a structural change in the vessel wall and typically in response to atherosclerotic plaque. The nature of coronary remodeling has been described in different clinical situations. However, remodeling characteristics of coronary arteries of diabetic patients have never been studied. Hypothesis: We tested the hypothesis that positive remodeling of coronary artery in response to atherosclerotic plaque in diabetic patients would be less compared to nondiabetic patients. Methods: Coronary intravascular ultrasound analysis of data in 26 consecutive patients (12 diabetic and 14 nondiabetic) was performed. Linear regression analyses of vessel area versus plaque area were carried out to establish a relation between the degree of plaque and the extent of remodeling in diabetic and nondiabetic groups. Results: The positive remodeling quantified as the slope of the regression line was similar in both the groups (diabetic group 1.32 and nondiabetic group 0.80) when all segments with different plaque areas were considered (P > 0.05). However, the diabetic group had greater positive remodeling in segments with plaque area less than 55%, as the slope for diabetic group was 2.01 and nondiabetic group was 1.40 (P < 0.05). Conclusions: Both the diabetic and nondiabetic patients had positive remodeling in response to atherosclerotic plaque formation. Diabetics had greater positive remodeling in the early stages of atherosclerosis compared to nondiabetics, thus providing evidence against our hypothesis. The adverse clinical outcomes in diabetics may not be due to inadequate positive remodeling of coronary arteries as previously thought. (ECHOCARDIOGRAPHY, Volume 21, February 2004)

Journal of Cellular Physiology, 1996

Following myocardial infarction, extracellular matrix (ECM) is disrupted, which leads to the gene... more Following myocardial infarction, extracellular matrix (ECM) is disrupted, which leads to the generation of collagen- and elastin-derived peptides (CDPs and EDPs, respectively). To investigate whether ECM-derived peptides (i.e., CDPs and EDPs) induce extracellular proteinases in human heart fibroblast (HHF) cells, we isolated CDP and EDP using gelfiltration and antibody affinity column chromatography. The CDP and EDP were characterized by their intrinsic fluorescence due to crosslink structure (pyridinoline and desmosine, respectively) and by immunoblot analysis using anti-desmosine antibody. Neutrophil elastase and cathepsin G were identified using selective chromogenic substrates and by their specific inhibition with alpha1-proteinase inhibitor and alpha1-antichymotrypsin, respectively. Elastase and cathepsin G were elevated in the infarcted tissue. Selective inhibition of matrix metalloproteinase (MMP) by a higher concentration of tetracycline or doxycycline in zymographic gels elicited an inhibition constant (IC50) of 278 +/- 10 microM and indicated that majority of MMP in the infarcted tissue is from fibroblast cells. The HHF proliferation was measured using an acid-phosphatase assay. The EDP and CDP induce HHF cell proliferation. After EDP treatment phenotypic (formation of pseudopodia) changes were observed in HHF cells. To measure whether phenotypic changes by EDP or CDP are associated with MMP and tissue inhibitor of metalloproteinase (TIMP) expression in HHF cells, we measured MMP and TIMP expression by zymographic and Northern blot (mRNA) analyses. The expression of MMP and TIMP were upregulated at both the protein and gene transcription levels. These results suggested that during ischemic cardiomyopathy, initially neutrophil proteinase activates latent myocardial MMP which can degrade ECM, which continuously degrades if not controlled by TIMP, leading to ventricular dilatation and dysfunction.