Laxmansa Katwa - Academia.edu (original) (raw)
Papers by Laxmansa Katwa
Journal of Medicinal Food, 2011
The objective of this study was to examine the extent to which bitter melon seed (BMS) alleviates... more The objective of this study was to examine the extent to which bitter melon seed (BMS) alleviates the symptoms associated with metabolic syndrome and elucidate the mechanism by which BMS exerts beneficial effects. Threemonth-old female Zucker rats were assigned to following groups: lean control (L-Ctrl), obese control (O-Ctrl), and obese þ BMS (O-BMS). The control groups were fed AIN-93M purified rodent diet, and the O-BMS group was fed AIN-93M diet modified to contain 3.0% (wt=wt) ground BMS for 100 days. After 100 days of treatment, BMS supplementation in the obese rats lowered the total serum cholesterol by 38% and low-density lipoprotein-cholesterol levels by about 52% and increased the ratio of serum high-density lipoprotein-cholesterol to total cholesterol compared to the O-Ctrl group. The percentage of total liver lipids was about 32% lower and serum triglyceride levels were 71% higher in the O-BMS group compared to the O-Ctrl group. Serum glucose levels were significantly lowered partly because of the increase in the serum insulin levels in the BMS-based diet groups. BMS supplementation increased the expression of peroxisome proliferatoractivated receptor-g (PPAR-g) in the white adipose tissue of the obese rats significantly (P < .05) and down-regulated the expression of PPAR-g, nuclear factor-kB (NF-kB), and interferon-g mRNA in heart tissue of the obese rats. The findings of this study suggest that BMS improves the serum and liver lipid profiles and serum glucose levels by modulating PPAR-g gene expression. To our knowledge, this study for the first time shows that BMS exerts cardioprotective effects by down-regulating the NF-kB inflammatory pathway.
Biochemical and Biophysical Research Communications, Aug 1, 2019
Previous studies have extensively demonstrated the effect of endothelin-1 (ET-1), angiotensin II ... more Previous studies have extensively demonstrated the effect of endothelin-1 (ET-1), angiotensin II (Ang II), and TGF-b1 on the stimulation of collagen type I expression in cardiac myofibroblasts. However, the role of pro-remodeling peptides in the transcriptional regulation of the collagen promoter remains unclear. Thus, the purpose of this study was to investigate the net regulatory effects of pro-remodeling peptides on collagen type I promoter activity. Constructs of various lengths (300 bp, 1.1 kbp, 1.7 kbp, 2.3 kbp and 3.5 kbp) of the rat collagen a1(I) promoter were transfected into cardiac myofibroblasts in vitro and promoter activity was measured using chloramphenicol acetyl transferase (CAT) assays. Reduced promoter activity occurred across all treatments in myofibroblasts transfected with the 1.7 kbp construct. ET-1 was unable to increase promoter activity with constructs 300, 1.1, and 1.7 kbp, but induced promoter activity in cells with the 2.3 kbp construct. Additionally, while a combination of pro-remodeling peptides induced promoter activity across constructs, the resultant increase in the 2.3 and 3.5 kbp constructs were comparable to that observed from ET-1 treatment alone. Lastly, cells transfected with the entire promoter sequence had the lowest promoter activity. This data suggests that the collagen promoter is tightly regulated and that pro-remodeling factors produce an overall net effect on collagen expression, rather than additive.
Amino Acids, Oct 25, 2008
Visfatin is a newly identified 52 kD adipocytokine that appears to have insulinomimetic propertie... more Visfatin is a newly identified 52 kD adipocytokine that appears to have insulinomimetic properties. We examined visfatin expression in visceral fat from lean and pregnant women. Visfatin gene expression was seven times higher in omental fat of pregnant women than in lean women. Both immunohistochemistry and immunoblot confirmed that visfatin protein was much higher in pregnant women than in nonpregnant women. However, serum visfatin was 20.8 +/- 7.7 ng/ml (n = 7) in lean women as compared to only a slight increase to 40.3 ng/ml in pregnant women (n = 4). We measured visfatin mRNA content of human placenta and found that placenta expresses high levels of visfatin mRNA and protein. At a concentration of 2 nM, visfatin and insulin produced nearly identical increase in glucose transport. The discrepancy between the elevated visfatin expression and tissue visfatin compared to only a small increase in serum visfatin is a matter of controversy. The data on serum visfatin concentrations are replete with contradictory data. Taken together, we suggest that visfatin is not a hormone. Instead, we propose that visfatin acts in either a paracrine or autocrine mode. This hypothesis would explain what various laboratories have found widely discrepant values for serum visfatin. Since visfatin potently and efficaciously induced glucose transport in a cell culture model, any hypothetical role for visfatin in pregnancy should include the possibility that it may play a role in maternal/fetal glucose metabolism or distribution and that it may do so by acting locally.
Journal of Pharmacology and Experimental Therapeutics, Jul 7, 2004
The role of endothelin-1 (ET) in tissue remodeling/fibrogenesis has been demonstrated in various ... more The role of endothelin-1 (ET) in tissue remodeling/fibrogenesis has been demonstrated in various in vitro and in vivo models. Our previous studies have revealed ET-induced expression of type I collagen in cardiac myofibroblasts (myoFb). Here we report that protein kinase C␦ (PKC␦) and mitogen-activated protein kinase/extracellular signal-regulated kinase-1/2 (MAPK/ERK1/2) play a role in ET-induced type I collagen expression using specific pharmacological inhibitors. The present study also reveals the expression of various isoforms of PKC including PKC␣, PKCI, PKCII, PKC␥, PKC␦, PKC⑀, PKC, and PKC in cardiac myoFb. Our results from mRNA and protein studies demonstrate that calphostin-C, a PKC inhibitor, decreased the ET-induced type I collagen expression suggesting a role for the PKC pathway. Further treatment with rottlerin, a PKC␦ isoform-specific inhibitor, demonstrated attenuation of 80 to 90% of type I collagen expression induced
American Journal of Physiology-heart and Circulatory Physiology, Sep 1, 2003
cently it was demonstrated that treatment with a nonselective endothelin (ET) receptor antagonist... more cently it was demonstrated that treatment with a nonselective endothelin (ET) receptor antagonist significantly reduces myocardial infarct size, which suggests a major role for ET in tissue repair following myocardial infarction (MI). Tissue repair and remodeling found at the site of MI are mainly attributed to myofibroblasts (myoFbs), which are phenotypically transformed fibroblasts that express ␣-smooth muscle actin. It is unclear whether myoFbs generate ET peptides and consequentially regulate pathophysiological functions de novo through expression of the ET-1 precursor (prepro-ET-1), ET-converting enzyme-1 (ECE-1), a metalloprotease that is required to convert Big ET-1 to ET-1 and ET receptors. To address these intriguing questions, we used cultured myoFbs isolated from 4-wk-old MI scar tissue. In cultured cells, we found: 1) expression of mRNA for ET precursor gene (ppET1), ECE-1, and ETA and ETB receptors by semiquantitative RT-PCR; 2) phosphoramidon-sensitive ECE-1 activity, which converts Big ET-1 to biologically active peptide ET-1; 3) expression of ET A and ETB receptors; 4) elaboration of Big ET-1 and ET-1 peptides in myoFb culture media; and 5) upregulation of type I collagen gene expression and synthesis by ET, which was blocked by bosentan (a nonselective ET Aand ET B receptor blocker). These studies clearly indicated that myoFbs express and generate ET-1 and receptormediated modulation of type I collagen expression by ET-1. Locally generated ET-1 may contribute to tissue repair of the infarcted heart in an autocrine/paracrine manner.
Enzyme and microbial technology, Jul 1, 1989
Kluyveromyces fragilis, the lactose-fermenting yeast, was made permeable to the disaccharide lact... more Kluyveromyces fragilis, the lactose-fermenting yeast, was made permeable to the disaccharide lactose using the surfactant digitonin. Optimal fl-galactosidase activity was observed when the cells were treated with 0.1% digitonin at room temperature for 30 min. The activity measured in these permeabilized cells was 400-to 500-fold greater than in the untreated cells and 25% more than in the cell-free extract prepared by toluene autolysis. These permeabilized cells rapidly hydrolysed lactose in whole milk and sweet whey to glucose and galactose. The glucose was not further degraded by permeabilized cells. In contrast, the untreated cells metabolized the glucose to ethanol.
The FASEB Journal, Apr 1, 2020
Frontiers in Cardiovascular Medicine, Nov 22, 2021
Introduction: In this study, we determined the influence of intrinsic exercise capacity on the va... more Introduction: In this study, we determined the influence of intrinsic exercise capacity on the vascular adaptive responses to hind limb ischemia. High Capacity Running, HCR; Low Capacity Running, LCR, rats were used to assess intrinsic aerobic capacity effects on adaptive responses to ischemia. Methods: Muscle samples from both ischemic and non-ischemic limb in both strains were compared, histologically for the muscle-capillary relationship, and functionally using microspheres to track blood flow and muscle stimulation to test fatigability. PCR was used to identify the differences in gene expression between the phenotypes following occlusive ischemia. Results: Prior to ligation, there were not significant differences between the phenotypes in the exhaustion time with high frequency pacing. Following ligation, LCR decreased significantly in the exhaustion time compare with HCRs (437 ± 47 vs. 824 ± 56, p < 0.001). The immediate decrease in flow was significantly more severe in LCRs than HCRs (52.5 vs. 37.8%, p < 0.001). VEGF, eNOS, and ANG2 (but not ANG1) gene expression were decreased in LCRs vs. HCRs before occlusion, and increased significantly in LCRs 14D after occlusion, but not in HCRs. LCR capillary density (CD) was significantly lower at all time points after occlusion (LCR 7D = 564.76 ± 40.5, LCR 14D = 507.48 ± 54.2, both p < 0.05 vs. HCR for respective time point). NCAF increased significantly in HCR and LCR in response to ischemia. Summary: These results suggest that LCR confers increased risk for ischemic injury and is subject to delayed and less effective adaptive response to ischemic stress.
Pediatric Research, Mar 1, 2005
Recent studies suggest a role for antioxidants in the prevention of pulmonary hypoplasia associat... more Recent studies suggest a role for antioxidants in the prevention of pulmonary hypoplasia associated with congenital diaphragmatic hernia (CDH). We studied the effects of vitamin E in the nitrofen-rat model of CDH. After an initial fast, timedpregnant Sprague-Dawley rats were gavage-fed nitrofen at gestational day 11 (term is 22 d). On the same day, one group was given a s.c. injection of vitamin E in alcohol; a second group was given an injection of alcohol alone. A third group received no treatment (control). Fetuses were delivered on day 21, and static pressure-volume curves were measured by immersion. Lungs were analyzed for total DNA and protein content by standard methods. A total of 203 fetuses were studied. Of 151 nitrofenexposed fetuses, 77% had CDH; 92% of these were right-sided. CDH was present in 82% of vehicle-treated fetuses and 71% of vitamin E-treated fetuses (p ϭ 0.17). Nitrofen-exposed fetuses not only were smaller than control fetuses but also had disproportionately smaller lungs and poorer lung function, even when CDH was absent; however, lung function was worse when CDH was present. Vitamin E treatment did not improve either lung growth or function, although there was a trend toward less CDH. We have shown, for the first time, that the lung hypoplasia seen in nitrofen-exposed rat fetuses is associated with a dramatic reduction in static lung function, even when CDH is not present. Finally, our findings support the notion that lung hypoplasia in the nitrofen-rat model is independent of CDH formation.
Frontiers in Cardiovascular Medicine, Nov 26, 2021
Conclusions: There is cardioprotection afforded by high intrinsic aerobic capacity, but it is not... more Conclusions: There is cardioprotection afforded by high intrinsic aerobic capacity, but it is not infinite/continuous, and may be overcome with sufficient injury burden. Phenotypic selection based on endurance running capacity preserved sex differences in response to both short and longer term coronary occlusive challenges. Outcomes could not be associated with differences in system characteristics such as circulating inflammatory mediators or autonomic nervous system influences, as similar phenotypic injury patterns were seen in vivo, and in isolated crystalloid perfused heart ex vivo.
Biochemical and Biophysical Research Communications, Jul 1, 2005
Recent studies suggest that there are strong parallels between development and patterning of the ... more Recent studies suggest that there are strong parallels between development and patterning of the vertebrate vascular system and the nervous system. While previous observations reported generation of vascular and neuronal progenitors from embryonic stem (ES) cells, the question of parallel development of vascular and neuronal cells in the same culture has not yet been investigated. Mouse D3 ES cells were cultured for 4 days in differentiation medium IMDM with 15% FBS in 100 mm non-adhesive Petri dishes to allow cells to aggregate and form embryoid bodies. At day 5, fibronectin or all-trans retinoic acid with fibronectin was added to the culture. On day 9, the embryoid bodies were seeded on poly-L-ornithine/fibronectin-coated plates. After plating, half of the plates were treated with laminin for 3 days and maintained for 1 week in Neurobasal media with B27. Here we show that ES cells differentiate into interconnected rhythmically contracting aggregates of functional cardiomyocytes and neurons. Double immunofluorescence with anti-phospholamban, anti-SERCA2 antibodies to detect cardiomyocytes and with anti-MAP2 antibodies to detect neurons revealed the cell aggregates consisting entirely of cardiomyocytes with neuronal cells located on the periphery or covering the aggregateÕs surface. The observed concurrent development of cardiomyocytes and neurons suggests bidirectional communication between both cell types. We propose that crosstalk between cardiovascular and neuronal progenitors is an important mechanism for the development of both systems.
Cells, Apr 13, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
American Journal of Physiology-heart and Circulatory Physiology, Oct 1, 2006
To examine ischemic tolerance in the absence of A1 adenosine receptors (A1ARs), isolated wild-typ... more To examine ischemic tolerance in the absence of A1 adenosine receptors (A1ARs), isolated wild-type (WT) and A1AR knockout (A1KO) murine hearts underwent global ischemia-reperfusion, and injury was measured in terms of functional recovery and efflux of lactate dehydrogenase (LDH). Hearts were analyzed by real-time RT-PCR both at baseline and at intervals during ischemia-reperfusion to determine whether compensatory expression of other adenosine receptor subtypes occurs with either A1AR deletion and/or ischemia-reperfusion. A1KO hearts had higher baseline coronary flow (CF) and left ventricular developed pressure (LVDP) than WT hearts, whereas heart rate was unchanged by A1AR deletion. After 20 min of ischemia, CF was attenuated in A 1KO compared with WT hearts, and this reduction persisted throughout reperfusion. Final recovery of LVDP was decreased in A1KO hearts (54.4 Ϯ 5.1 vs. WT 81.1 Ϯ 3.4% preischemic baseline) and correlated with higher diastolic pressure during reperfusion. Postischemic efflux of LDH was greater in A 1KO compared with WT hearts. Real-time RT-PCR demonstrated the absence of A 1AR transcript in A1KO hearts, and the message for A2A, A2B, and A3 adenosine receptors was similar in uninstrumented A1KO and WT hearts. Ischemia-reperfusion increased A 2B mRNA expression 2.5fold in both WT and A1KO hearts without changing A1 or A3 expression. In WT hearts, ischemia transiently doubled A2A mRNA, which returned to preischemic level upon reperfusion, a pattern not observed in A 1KO hearts. Together, these data affirm the cardioprotective role of A1ARs and suggest that induced expression of other adenosine receptor subtypes may participate in the response to ischemia-reperfusion in isolated murine hearts. gene expression; coronary flow; lactate dehydrogenase ADENOSINE HAS BROAD cardiovascular effects, including the ability to protect the heart from ischemia-reperfusion injury. Interacting with its four known receptor subtypes (A 1 , A 2A , A 2B , and A 3 receptors), adenosine serves as a homeostatic autacoid to moderate ischemia-induced imbalances of metabolic supply and demand (4, 7, 17, 33). A 1 adenosine receptor (A 1 AR) activation figures prominently in adenosinergic cardioprotection (7, 17, 24, 33-35, 48) in part through negative chronotropic, dromotropic, and inotropic responses as well as protec
Journal of Molecular and Cellular Cardiology, 1997
Vascular tissue engineering strategies using cell-seeded scaffolds require uniformly distributed ... more Vascular tissue engineering strategies using cell-seeded scaffolds require uniformly distributed vascular cells and sufficient extracellular matrix (ECM) production. However, acquiring sufficient ECM deposition into synthetic biomaterial scaffolds during the in vitro culture period prior to tissue implantation still remains challenging for vascular constructs. Two forms of vitamin C derivatives, ascorbic acid (AA) and sodium ascorbate (SA), are commonly supplemented in cell culture to promote ECM accumulation. However, the literature often refers to AA and SA interchangeably and their differential effects on cell growth and ECM molecule (glycosaminoglycan, collagen, elastin) accumulation have never been reported when used in mono-culture or co-culture systems developed with synthetic three dimensional (3-D) scaffolds. In this study, it was found that 200 µM AA stimulated an increase in cell number while SA (50, 100 and 200 µM) supported more calponin expression (immunostaining) and higher ECM accumulation from vascular smooth muscle cells (VSMCs) after 1 week in the degradable polar hydrophobic ionic polyurethane (D-PHI) scaffold. The influence of AA and SA on ECM deposition was also studied in VSMC-monocyte co-cultures in order to replicate some aspects of a wound healing environment in vitro, and compared to their effects in respective VSMC monocultures after 4 weeks. While 100 µM SA promoted ECM deposition in co-culture, the condition of 100 µM AA + 100 µM SA was more effective towards enhancing ECM accumulation in VSMC mono-culture after 4 weeks. The results demonstrated that AA and SA are not interchangeable and the different effects of AA and/or SA on ECM deposition was both culture system (co-culture vs. mono-culture) and culture period (1 week vs. 4 week) dependent. This study provides further insight into practical vascular tissue engineering strategies when using 3-D synthetic biomaterial-based constructs.
Journal of Food Biochemistry, Dec 1, 1982
A polyphenol oxidase [EC class 1.10.3] was purified from culture filtrates of Chaetomium thermoph... more A polyphenol oxidase [EC class 1.10.3] was purified from culture filtrates of Chaetomium thermophile Isolate o-453 by procedures including saltingout by ammonium sulfate and combined column chromatography on DEAE-Toyopearl 6505, Con A-Sepharose, hydroxylapatite, and Sephadex G-200. The final enzyme preparation was homogeneous on polyacrylamide gel disc electrophoresis. Its estimated molecular weight was approximately 98,000 by gel filtration. It showed maximum activity at pH 5.0 and at 55°C. The purified enzyme was very stable between pH 4.0 and 11.0 and up to 55°C. It was highly active toward d catechin (100%), phydroquinone (45.7%), and N,N-dimethyl-p-phenylenediamine (63.0%). Though pyrocatechol (22.6%) was oxidized to some extent, DL-DOPA (0.33%) and o-phenylenediamine (3.10) were hardly oxidized by the enzyme.
Journal of Pharmacology and Experimental Therapeutics, Mar 27, 2003
Endothelin-1 (ET-1) signaling mechanisms have been implicated in the pathogenesis of excess coron... more Endothelin-1 (ET-1) signaling mechanisms have been implicated in the pathogenesis of excess coronary artery disease in diabetic dyslipidemia. We hypothesized that in diabetic dyslipidemia ET-1-induced coronary smooth muscle calcium (Ca 2ϩ m) and tyrosine phosphorylation would be increased, and the lipid lowering agent, atorvastatin, would inhibit these increases. Male Yucatan miniature swine groups were treated for 20 weeks: normal low-fat fed control, high-fat/cholesterol fed (hyperlipidemic), hyperlipidemic made diabetic with alloxan (diabetic dyslipidemic), and diabetic dyslipidemic treated with atorvastatin (atorvastatin-treated). Blood glucose values were 5-fold greater in diabetic dyslipidemic and atorvastatin-treated versus control and hyperlipidemic. Total and low-density lipoprotein (LDL) plasma cholesterol in hyperlipidemic, diabetic dyslipidemic, and atorvastatin-treated were ϳ5-fold greater than control. Intravascular ultrasound detectable coronary disease and hypertriglyceridemia were only observed in diabetic dyslipidemic and were abolished by atorvastatin. In freshly
Molecular and Cellular Biochemistry, 1996
Earlier studies have demonstrated angiotensin II (AngII) and aldosterone (ALDO) each augment cult... more Earlier studies have demonstrated angiotensin II (AngII) and aldosterone (ALDO) each augment cultured adult rat cardiac fibroblast (CFb) collagen synthesis. Whether this involves type I collagen, the major structural protein of the myocardium, and represents a transcriptional event, is uncertain. Accordingly, the influence of AngII and ALDO on transcription and synthesis of fibrillar collagen and on collagenolytic activity was examined
The FASEB Journal, Apr 1, 2020
The FASEB Journal, Apr 1, 2020
Journal of Medicinal Food, 2011
The objective of this study was to examine the extent to which bitter melon seed (BMS) alleviates... more The objective of this study was to examine the extent to which bitter melon seed (BMS) alleviates the symptoms associated with metabolic syndrome and elucidate the mechanism by which BMS exerts beneficial effects. Threemonth-old female Zucker rats were assigned to following groups: lean control (L-Ctrl), obese control (O-Ctrl), and obese þ BMS (O-BMS). The control groups were fed AIN-93M purified rodent diet, and the O-BMS group was fed AIN-93M diet modified to contain 3.0% (wt=wt) ground BMS for 100 days. After 100 days of treatment, BMS supplementation in the obese rats lowered the total serum cholesterol by 38% and low-density lipoprotein-cholesterol levels by about 52% and increased the ratio of serum high-density lipoprotein-cholesterol to total cholesterol compared to the O-Ctrl group. The percentage of total liver lipids was about 32% lower and serum triglyceride levels were 71% higher in the O-BMS group compared to the O-Ctrl group. Serum glucose levels were significantly lowered partly because of the increase in the serum insulin levels in the BMS-based diet groups. BMS supplementation increased the expression of peroxisome proliferatoractivated receptor-g (PPAR-g) in the white adipose tissue of the obese rats significantly (P < .05) and down-regulated the expression of PPAR-g, nuclear factor-kB (NF-kB), and interferon-g mRNA in heart tissue of the obese rats. The findings of this study suggest that BMS improves the serum and liver lipid profiles and serum glucose levels by modulating PPAR-g gene expression. To our knowledge, this study for the first time shows that BMS exerts cardioprotective effects by down-regulating the NF-kB inflammatory pathway.
Biochemical and Biophysical Research Communications, Aug 1, 2019
Previous studies have extensively demonstrated the effect of endothelin-1 (ET-1), angiotensin II ... more Previous studies have extensively demonstrated the effect of endothelin-1 (ET-1), angiotensin II (Ang II), and TGF-b1 on the stimulation of collagen type I expression in cardiac myofibroblasts. However, the role of pro-remodeling peptides in the transcriptional regulation of the collagen promoter remains unclear. Thus, the purpose of this study was to investigate the net regulatory effects of pro-remodeling peptides on collagen type I promoter activity. Constructs of various lengths (300 bp, 1.1 kbp, 1.7 kbp, 2.3 kbp and 3.5 kbp) of the rat collagen a1(I) promoter were transfected into cardiac myofibroblasts in vitro and promoter activity was measured using chloramphenicol acetyl transferase (CAT) assays. Reduced promoter activity occurred across all treatments in myofibroblasts transfected with the 1.7 kbp construct. ET-1 was unable to increase promoter activity with constructs 300, 1.1, and 1.7 kbp, but induced promoter activity in cells with the 2.3 kbp construct. Additionally, while a combination of pro-remodeling peptides induced promoter activity across constructs, the resultant increase in the 2.3 and 3.5 kbp constructs were comparable to that observed from ET-1 treatment alone. Lastly, cells transfected with the entire promoter sequence had the lowest promoter activity. This data suggests that the collagen promoter is tightly regulated and that pro-remodeling factors produce an overall net effect on collagen expression, rather than additive.
Amino Acids, Oct 25, 2008
Visfatin is a newly identified 52 kD adipocytokine that appears to have insulinomimetic propertie... more Visfatin is a newly identified 52 kD adipocytokine that appears to have insulinomimetic properties. We examined visfatin expression in visceral fat from lean and pregnant women. Visfatin gene expression was seven times higher in omental fat of pregnant women than in lean women. Both immunohistochemistry and immunoblot confirmed that visfatin protein was much higher in pregnant women than in nonpregnant women. However, serum visfatin was 20.8 +/- 7.7 ng/ml (n = 7) in lean women as compared to only a slight increase to 40.3 ng/ml in pregnant women (n = 4). We measured visfatin mRNA content of human placenta and found that placenta expresses high levels of visfatin mRNA and protein. At a concentration of 2 nM, visfatin and insulin produced nearly identical increase in glucose transport. The discrepancy between the elevated visfatin expression and tissue visfatin compared to only a small increase in serum visfatin is a matter of controversy. The data on serum visfatin concentrations are replete with contradictory data. Taken together, we suggest that visfatin is not a hormone. Instead, we propose that visfatin acts in either a paracrine or autocrine mode. This hypothesis would explain what various laboratories have found widely discrepant values for serum visfatin. Since visfatin potently and efficaciously induced glucose transport in a cell culture model, any hypothetical role for visfatin in pregnancy should include the possibility that it may play a role in maternal/fetal glucose metabolism or distribution and that it may do so by acting locally.
Journal of Pharmacology and Experimental Therapeutics, Jul 7, 2004
The role of endothelin-1 (ET) in tissue remodeling/fibrogenesis has been demonstrated in various ... more The role of endothelin-1 (ET) in tissue remodeling/fibrogenesis has been demonstrated in various in vitro and in vivo models. Our previous studies have revealed ET-induced expression of type I collagen in cardiac myofibroblasts (myoFb). Here we report that protein kinase C␦ (PKC␦) and mitogen-activated protein kinase/extracellular signal-regulated kinase-1/2 (MAPK/ERK1/2) play a role in ET-induced type I collagen expression using specific pharmacological inhibitors. The present study also reveals the expression of various isoforms of PKC including PKC␣, PKCI, PKCII, PKC␥, PKC␦, PKC⑀, PKC, and PKC in cardiac myoFb. Our results from mRNA and protein studies demonstrate that calphostin-C, a PKC inhibitor, decreased the ET-induced type I collagen expression suggesting a role for the PKC pathway. Further treatment with rottlerin, a PKC␦ isoform-specific inhibitor, demonstrated attenuation of 80 to 90% of type I collagen expression induced
American Journal of Physiology-heart and Circulatory Physiology, Sep 1, 2003
cently it was demonstrated that treatment with a nonselective endothelin (ET) receptor antagonist... more cently it was demonstrated that treatment with a nonselective endothelin (ET) receptor antagonist significantly reduces myocardial infarct size, which suggests a major role for ET in tissue repair following myocardial infarction (MI). Tissue repair and remodeling found at the site of MI are mainly attributed to myofibroblasts (myoFbs), which are phenotypically transformed fibroblasts that express ␣-smooth muscle actin. It is unclear whether myoFbs generate ET peptides and consequentially regulate pathophysiological functions de novo through expression of the ET-1 precursor (prepro-ET-1), ET-converting enzyme-1 (ECE-1), a metalloprotease that is required to convert Big ET-1 to ET-1 and ET receptors. To address these intriguing questions, we used cultured myoFbs isolated from 4-wk-old MI scar tissue. In cultured cells, we found: 1) expression of mRNA for ET precursor gene (ppET1), ECE-1, and ETA and ETB receptors by semiquantitative RT-PCR; 2) phosphoramidon-sensitive ECE-1 activity, which converts Big ET-1 to biologically active peptide ET-1; 3) expression of ET A and ETB receptors; 4) elaboration of Big ET-1 and ET-1 peptides in myoFb culture media; and 5) upregulation of type I collagen gene expression and synthesis by ET, which was blocked by bosentan (a nonselective ET Aand ET B receptor blocker). These studies clearly indicated that myoFbs express and generate ET-1 and receptormediated modulation of type I collagen expression by ET-1. Locally generated ET-1 may contribute to tissue repair of the infarcted heart in an autocrine/paracrine manner.
Enzyme and microbial technology, Jul 1, 1989
Kluyveromyces fragilis, the lactose-fermenting yeast, was made permeable to the disaccharide lact... more Kluyveromyces fragilis, the lactose-fermenting yeast, was made permeable to the disaccharide lactose using the surfactant digitonin. Optimal fl-galactosidase activity was observed when the cells were treated with 0.1% digitonin at room temperature for 30 min. The activity measured in these permeabilized cells was 400-to 500-fold greater than in the untreated cells and 25% more than in the cell-free extract prepared by toluene autolysis. These permeabilized cells rapidly hydrolysed lactose in whole milk and sweet whey to glucose and galactose. The glucose was not further degraded by permeabilized cells. In contrast, the untreated cells metabolized the glucose to ethanol.
The FASEB Journal, Apr 1, 2020
Frontiers in Cardiovascular Medicine, Nov 22, 2021
Introduction: In this study, we determined the influence of intrinsic exercise capacity on the va... more Introduction: In this study, we determined the influence of intrinsic exercise capacity on the vascular adaptive responses to hind limb ischemia. High Capacity Running, HCR; Low Capacity Running, LCR, rats were used to assess intrinsic aerobic capacity effects on adaptive responses to ischemia. Methods: Muscle samples from both ischemic and non-ischemic limb in both strains were compared, histologically for the muscle-capillary relationship, and functionally using microspheres to track blood flow and muscle stimulation to test fatigability. PCR was used to identify the differences in gene expression between the phenotypes following occlusive ischemia. Results: Prior to ligation, there were not significant differences between the phenotypes in the exhaustion time with high frequency pacing. Following ligation, LCR decreased significantly in the exhaustion time compare with HCRs (437 ± 47 vs. 824 ± 56, p < 0.001). The immediate decrease in flow was significantly more severe in LCRs than HCRs (52.5 vs. 37.8%, p < 0.001). VEGF, eNOS, and ANG2 (but not ANG1) gene expression were decreased in LCRs vs. HCRs before occlusion, and increased significantly in LCRs 14D after occlusion, but not in HCRs. LCR capillary density (CD) was significantly lower at all time points after occlusion (LCR 7D = 564.76 ± 40.5, LCR 14D = 507.48 ± 54.2, both p < 0.05 vs. HCR for respective time point). NCAF increased significantly in HCR and LCR in response to ischemia. Summary: These results suggest that LCR confers increased risk for ischemic injury and is subject to delayed and less effective adaptive response to ischemic stress.
Pediatric Research, Mar 1, 2005
Recent studies suggest a role for antioxidants in the prevention of pulmonary hypoplasia associat... more Recent studies suggest a role for antioxidants in the prevention of pulmonary hypoplasia associated with congenital diaphragmatic hernia (CDH). We studied the effects of vitamin E in the nitrofen-rat model of CDH. After an initial fast, timedpregnant Sprague-Dawley rats were gavage-fed nitrofen at gestational day 11 (term is 22 d). On the same day, one group was given a s.c. injection of vitamin E in alcohol; a second group was given an injection of alcohol alone. A third group received no treatment (control). Fetuses were delivered on day 21, and static pressure-volume curves were measured by immersion. Lungs were analyzed for total DNA and protein content by standard methods. A total of 203 fetuses were studied. Of 151 nitrofenexposed fetuses, 77% had CDH; 92% of these were right-sided. CDH was present in 82% of vehicle-treated fetuses and 71% of vitamin E-treated fetuses (p ϭ 0.17). Nitrofen-exposed fetuses not only were smaller than control fetuses but also had disproportionately smaller lungs and poorer lung function, even when CDH was absent; however, lung function was worse when CDH was present. Vitamin E treatment did not improve either lung growth or function, although there was a trend toward less CDH. We have shown, for the first time, that the lung hypoplasia seen in nitrofen-exposed rat fetuses is associated with a dramatic reduction in static lung function, even when CDH is not present. Finally, our findings support the notion that lung hypoplasia in the nitrofen-rat model is independent of CDH formation.
Frontiers in Cardiovascular Medicine, Nov 26, 2021
Conclusions: There is cardioprotection afforded by high intrinsic aerobic capacity, but it is not... more Conclusions: There is cardioprotection afforded by high intrinsic aerobic capacity, but it is not infinite/continuous, and may be overcome with sufficient injury burden. Phenotypic selection based on endurance running capacity preserved sex differences in response to both short and longer term coronary occlusive challenges. Outcomes could not be associated with differences in system characteristics such as circulating inflammatory mediators or autonomic nervous system influences, as similar phenotypic injury patterns were seen in vivo, and in isolated crystalloid perfused heart ex vivo.
Biochemical and Biophysical Research Communications, Jul 1, 2005
Recent studies suggest that there are strong parallels between development and patterning of the ... more Recent studies suggest that there are strong parallels between development and patterning of the vertebrate vascular system and the nervous system. While previous observations reported generation of vascular and neuronal progenitors from embryonic stem (ES) cells, the question of parallel development of vascular and neuronal cells in the same culture has not yet been investigated. Mouse D3 ES cells were cultured for 4 days in differentiation medium IMDM with 15% FBS in 100 mm non-adhesive Petri dishes to allow cells to aggregate and form embryoid bodies. At day 5, fibronectin or all-trans retinoic acid with fibronectin was added to the culture. On day 9, the embryoid bodies were seeded on poly-L-ornithine/fibronectin-coated plates. After plating, half of the plates were treated with laminin for 3 days and maintained for 1 week in Neurobasal media with B27. Here we show that ES cells differentiate into interconnected rhythmically contracting aggregates of functional cardiomyocytes and neurons. Double immunofluorescence with anti-phospholamban, anti-SERCA2 antibodies to detect cardiomyocytes and with anti-MAP2 antibodies to detect neurons revealed the cell aggregates consisting entirely of cardiomyocytes with neuronal cells located on the periphery or covering the aggregateÕs surface. The observed concurrent development of cardiomyocytes and neurons suggests bidirectional communication between both cell types. We propose that crosstalk between cardiovascular and neuronal progenitors is an important mechanism for the development of both systems.
Cells, Apr 13, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
American Journal of Physiology-heart and Circulatory Physiology, Oct 1, 2006
To examine ischemic tolerance in the absence of A1 adenosine receptors (A1ARs), isolated wild-typ... more To examine ischemic tolerance in the absence of A1 adenosine receptors (A1ARs), isolated wild-type (WT) and A1AR knockout (A1KO) murine hearts underwent global ischemia-reperfusion, and injury was measured in terms of functional recovery and efflux of lactate dehydrogenase (LDH). Hearts were analyzed by real-time RT-PCR both at baseline and at intervals during ischemia-reperfusion to determine whether compensatory expression of other adenosine receptor subtypes occurs with either A1AR deletion and/or ischemia-reperfusion. A1KO hearts had higher baseline coronary flow (CF) and left ventricular developed pressure (LVDP) than WT hearts, whereas heart rate was unchanged by A1AR deletion. After 20 min of ischemia, CF was attenuated in A 1KO compared with WT hearts, and this reduction persisted throughout reperfusion. Final recovery of LVDP was decreased in A1KO hearts (54.4 Ϯ 5.1 vs. WT 81.1 Ϯ 3.4% preischemic baseline) and correlated with higher diastolic pressure during reperfusion. Postischemic efflux of LDH was greater in A 1KO compared with WT hearts. Real-time RT-PCR demonstrated the absence of A 1AR transcript in A1KO hearts, and the message for A2A, A2B, and A3 adenosine receptors was similar in uninstrumented A1KO and WT hearts. Ischemia-reperfusion increased A 2B mRNA expression 2.5fold in both WT and A1KO hearts without changing A1 or A3 expression. In WT hearts, ischemia transiently doubled A2A mRNA, which returned to preischemic level upon reperfusion, a pattern not observed in A 1KO hearts. Together, these data affirm the cardioprotective role of A1ARs and suggest that induced expression of other adenosine receptor subtypes may participate in the response to ischemia-reperfusion in isolated murine hearts. gene expression; coronary flow; lactate dehydrogenase ADENOSINE HAS BROAD cardiovascular effects, including the ability to protect the heart from ischemia-reperfusion injury. Interacting with its four known receptor subtypes (A 1 , A 2A , A 2B , and A 3 receptors), adenosine serves as a homeostatic autacoid to moderate ischemia-induced imbalances of metabolic supply and demand (4, 7, 17, 33). A 1 adenosine receptor (A 1 AR) activation figures prominently in adenosinergic cardioprotection (7, 17, 24, 33-35, 48) in part through negative chronotropic, dromotropic, and inotropic responses as well as protec
Journal of Molecular and Cellular Cardiology, 1997
Vascular tissue engineering strategies using cell-seeded scaffolds require uniformly distributed ... more Vascular tissue engineering strategies using cell-seeded scaffolds require uniformly distributed vascular cells and sufficient extracellular matrix (ECM) production. However, acquiring sufficient ECM deposition into synthetic biomaterial scaffolds during the in vitro culture period prior to tissue implantation still remains challenging for vascular constructs. Two forms of vitamin C derivatives, ascorbic acid (AA) and sodium ascorbate (SA), are commonly supplemented in cell culture to promote ECM accumulation. However, the literature often refers to AA and SA interchangeably and their differential effects on cell growth and ECM molecule (glycosaminoglycan, collagen, elastin) accumulation have never been reported when used in mono-culture or co-culture systems developed with synthetic three dimensional (3-D) scaffolds. In this study, it was found that 200 µM AA stimulated an increase in cell number while SA (50, 100 and 200 µM) supported more calponin expression (immunostaining) and higher ECM accumulation from vascular smooth muscle cells (VSMCs) after 1 week in the degradable polar hydrophobic ionic polyurethane (D-PHI) scaffold. The influence of AA and SA on ECM deposition was also studied in VSMC-monocyte co-cultures in order to replicate some aspects of a wound healing environment in vitro, and compared to their effects in respective VSMC monocultures after 4 weeks. While 100 µM SA promoted ECM deposition in co-culture, the condition of 100 µM AA + 100 µM SA was more effective towards enhancing ECM accumulation in VSMC mono-culture after 4 weeks. The results demonstrated that AA and SA are not interchangeable and the different effects of AA and/or SA on ECM deposition was both culture system (co-culture vs. mono-culture) and culture period (1 week vs. 4 week) dependent. This study provides further insight into practical vascular tissue engineering strategies when using 3-D synthetic biomaterial-based constructs.
Journal of Food Biochemistry, Dec 1, 1982
A polyphenol oxidase [EC class 1.10.3] was purified from culture filtrates of Chaetomium thermoph... more A polyphenol oxidase [EC class 1.10.3] was purified from culture filtrates of Chaetomium thermophile Isolate o-453 by procedures including saltingout by ammonium sulfate and combined column chromatography on DEAE-Toyopearl 6505, Con A-Sepharose, hydroxylapatite, and Sephadex G-200. The final enzyme preparation was homogeneous on polyacrylamide gel disc electrophoresis. Its estimated molecular weight was approximately 98,000 by gel filtration. It showed maximum activity at pH 5.0 and at 55°C. The purified enzyme was very stable between pH 4.0 and 11.0 and up to 55°C. It was highly active toward d catechin (100%), phydroquinone (45.7%), and N,N-dimethyl-p-phenylenediamine (63.0%). Though pyrocatechol (22.6%) was oxidized to some extent, DL-DOPA (0.33%) and o-phenylenediamine (3.10) were hardly oxidized by the enzyme.
Journal of Pharmacology and Experimental Therapeutics, Mar 27, 2003
Endothelin-1 (ET-1) signaling mechanisms have been implicated in the pathogenesis of excess coron... more Endothelin-1 (ET-1) signaling mechanisms have been implicated in the pathogenesis of excess coronary artery disease in diabetic dyslipidemia. We hypothesized that in diabetic dyslipidemia ET-1-induced coronary smooth muscle calcium (Ca 2ϩ m) and tyrosine phosphorylation would be increased, and the lipid lowering agent, atorvastatin, would inhibit these increases. Male Yucatan miniature swine groups were treated for 20 weeks: normal low-fat fed control, high-fat/cholesterol fed (hyperlipidemic), hyperlipidemic made diabetic with alloxan (diabetic dyslipidemic), and diabetic dyslipidemic treated with atorvastatin (atorvastatin-treated). Blood glucose values were 5-fold greater in diabetic dyslipidemic and atorvastatin-treated versus control and hyperlipidemic. Total and low-density lipoprotein (LDL) plasma cholesterol in hyperlipidemic, diabetic dyslipidemic, and atorvastatin-treated were ϳ5-fold greater than control. Intravascular ultrasound detectable coronary disease and hypertriglyceridemia were only observed in diabetic dyslipidemic and were abolished by atorvastatin. In freshly
Molecular and Cellular Biochemistry, 1996
Earlier studies have demonstrated angiotensin II (AngII) and aldosterone (ALDO) each augment cult... more Earlier studies have demonstrated angiotensin II (AngII) and aldosterone (ALDO) each augment cultured adult rat cardiac fibroblast (CFb) collagen synthesis. Whether this involves type I collagen, the major structural protein of the myocardium, and represents a transcriptional event, is uncertain. Accordingly, the influence of AngII and ALDO on transcription and synthesis of fibrillar collagen and on collagenolytic activity was examined
The FASEB Journal, Apr 1, 2020
The FASEB Journal, Apr 1, 2020