Biomedical subjects

J Chattopadhyay

Publications and source records attributed to J Chattopadhyay.

14 recordsLinked to original sources

PubMed1996

Predictors of survival in continuous ambulatory peritoneal dialysis patients: a five-year prospective study.

Our objective was to examine the influence of various demographic, clinical, and enrollment biochemical variables on the long-term survival of continuous ambulatory peritoneal dialysis (CAPD) patients. This was a prospective cohort study investigating the relationship between demographics and enrollment biochemical markers and mortality in CAPD patients in a CAPD unit in a large tertiary care teaching hospital. One hundred and sixty-nine patients in the CAPD program were enrolled between 1989 and 1994, and were followed up to 60 months. Independent predictors of mortality determined by Cox proportional hazards model included age, diabetes, serum albumin and creatinine. Enrollment level of serum albumin, and creatine can predict mortality in CAPD patients up to 60 months. Markers of visceral and somatic nutrition at enrollment are important predictors of mortality in CAPD patients up to five years.

Adult↗

PubMed1996

Is an elevated level of serum lipoprotein (a) a risk factor for cardiovascular disease in CAPD patients?

Cardiovascular disease (CVD) is the single most important cause of mortality in hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) patients. An increased lipoprotein (a) [Lp(a)] level in HD patients is associated with CVD. However, Lp(a) levels in CAPD patients are controversial, and their association with CVD has not been established. In the present study, prevalent CAPD and HD patients [excluding those who were human immunodeficiency virus (HIV)-positive] attending the Long Island College Hospital from June, 1990 to July, 1995 underwent analysis of lipid profile including Lp(a). Total and low-density lipoprotein cholesterol, triglycerides, apolipoprotein (apo) A, and apo B were all significantly increased in CAPD patients compared to HD patients. Serum Lp(a) levels were also significantly higher in CAPD patients than in HD patients (51 +/- 32 vs 34 +/- 23 mg/dL, p < 0.001). CAPD patients who had a history of myocardial infarction (MI) or coronary artery disease (CAD) at enrollment had significantly higher Lp(a) levels compared to those who did not have a history of MI or CAD. CAPD patients who died of CVD had higher Lp(a) levels than patients who died of non-CVD causes. In the Cox model with backward stepwise selection, a history of CVD was associated with a significantly elevated relative risk (RR) of mortality (RR = 1.84, p = 0.014). Expected survival by all causes of mortality and by cardiac mortality was significantly shorter in patients with a history of CVD than in those without a history of CVD. Thus, elevated Lp(a) is related to increased CVD and therefore may contribute to increased mortality in CAPD patients.

Adult↗

PubMed1995

Markers for survival in dialysis: a seven-year prospective study.

Serum biochemical markers suggestive of undernutrition are directly correlated with mortality in hemodialysis and peritoneal dialysis patients. In particular, serum albumin is the most powerful predictor of survival. We have prospectively examined the relationship of single baseline measurements of serum albumin, cholesterol, creatinine, apoproteins, and prealbumin in 250 hemodialysis patients and 140 patients maintained on continuous ambulatory peritoneal dialysis (CAPD) monitored up to 7 years (1987 to 1994). Other variables studied included age, race, gender, diabetes, and number of months on dialysis. Observed survival was computed by the Kaplan-Meier method. Cox's proportional hazards model was used to determine independent predictors of mortality risk. Age, diabetes, prior months on dialysis, and low levels of serum albumin, creatinine, and cholesterol were important and independent predictors of mortality risk in hemodialysis patients. For peritoneal dialysis patients, the independent predictors of mortality risk were age, diabetes, and low serum albumin and serum creatinine. Prealbumin, a serum protein with rapid turnover and relatively small pool, was an important and independent risk predictor in both hemodialysis and CAPD patients. In addition, prealbumin was more highly correlated with other nutritional markers than was albumin. In summary, these findings suggest that biochemical measures associated with visceral and somatic protein depletion are predominant long-term mortality risk factors in patients maintained on hemodialysis and CAPD.

Adult↗

PubMed1993

Turing structure during embryogenesis.

A non-linear reaction-diffusion model of the epigenetic system involving the synthesis and simultaneous intercellular self and cross-diffusion of the activator and inhibitor during embryogenesis has been proposed. It has been observed that the system spontaneously emerges into a stationary dissipative (Turing) structure only in the presence of positive cross-diffusion. That the stationary structure, thus evolved, has been shown to be globally asymptotically stable by using a suitable Liapunov's function.

Animals↗

PubMed1992

1,2-Diacylglycerol does not mediate the stimulatory effect of phorbol 12-myristate 13-acetate on phosphatidylcholine synthesis in NIH 3T3 fibroblasts.

In HeLa cells, increased 1,2-diacylglycerol (1,2-DAG) has been suggested to mediate the stimulatory effect of phorbol 12-myristate 13-acetate (PMA) on phosphatidylcholine (PtdCho) biosynthesis (A. K. Utal, H. Jamil, and D. E. Vance, 1991, J. Biol. Chem. 266, 24,084-24,091). The aim of this study was to examine if 1,2-DAG might have a similar mediatory role in NIH 3T3 fibroblasts. In these cells, PMA-induced hydrolysis of PtdCho and the formation of secondary product 1,2-DAG was inhibited by exposing the cells to either 300 mM ethanol for 15 min (less than 80% inhibition) or 43 degrees C for 60 min (less than 50% inhibition). In contrast, neither ethanol nor heat-treatment caused significant inhibition of PMA-stimulated PtdCho synthesis. These data indicate that in NIH 3T3 fibroblasts, 1,2-DAG is not a mediator of the stimulatory action of PMA on PtdCho synthesis.

Cell Line↗

PubMed1992

Nonesterified fatty acids in normal and diabetic rat sciatic nerve.

Alloxan-induced diabetes in rats results in elevated levels of nonesterified fatty acids (NEFA) in whole sciatic nerve and its endoneurium. Increases in NEFA levels are more pronounced in whole diabetic nerve (40% over control) than in its endoneurial portion (20-30%). Alterations in the composition of phospholipid fatty acids are observed as well, including an increase in linoleate (18:2n-6) in endoneurial phosphatidylethanolamine and a decrease in arachidonate (20:4n-6) in both phosphatidylethanolamine and phosphatidylinositol of diabetic nerve.

Alloxan↗

PubMed1992

Formation of a regular dissipative structure: a bifurcation and non-linear analysis.

A non-linear reaction diffusion model of a negative feedback epigenetic control system is presented. The model involves synthesis of the mitotic inducing and inhibiting proteins, simultaneously with intercellular self-diffusion and cross-diffusion of the latter only. The importance of negative cross-diffusion for creating a regular dissipative structure is shown. A bifurcation analysis of the non-linear diffusive system has been performed and it is concluded that bifurcation is supercritical. Lastly, using Liapunov's direct method, it is shown that the pattern evolved by the system is globally asymptotically stable.

Cell Differentiation↗

PubMed1991

Ethanol potentiates the stimulatory effects of phorbol ester, sphingosine and 4-hydroxynonenal on the hydrolysis of phosphatidylethanolamine in NIH 3T3 cells.

Ethanol and other alcohols have been shown to specifically stimulate phospholipase-D-mediated hydrolysis of phosphatidylethanolamine (PtdEtn) in NIH 3T3 fibroblasts. Here, we further examined the possible mechanism of this ethanol action. Ethanol (10-300 mM) and the protein kinase C (PKC) activator 12-O-tetradecanoyl-phorbol 13-acetate (TPA) had synergistic stimulatory effects on the degradation of preformed [14C]PtdEtn when added in combination to [14C]ethanolamine-labelled suspended NIH 3T3 cells 30 min after collection of cells by scraping. Scraping caused a transient increase, lasting for less than 30 min, in the cellular content of 1,2-diacylglycerol, another PKC activator. Initially (0-50 min incubation), the main water-soluble product of [14C]PtdEtn degradation in ethanol plus TPA-treated cells was [14C]ethanolamine, while later (90 min) the main product of [14C]PtdEtn hydrolysis was [14C]ethanolamine phosphate in the presence of these agents. Ethanol also potentiated the specific stimulatory effects of sphingosine (through phospholipase D) and 4-hydroxynonenal (not involving phospholipase D) on PtdEtn hydrolysis. The effects of these latter agents were unrelated to PKC activation. These data indicate that the observed potentiating effects of ethanol on PtdEtn hydrolysis do not involve direct regulation of PKC or phospholipase D activities.

Aldehydes↗

PubMed1991

Stimulation of phosphatidylcholine synthesis by activators of protein kinase C is dissociable from increased phospholipid hydrolysis.

The aim of this study was to clarify the relationship between the stimulatory effects of protein kinase C activators, including phorbol 12-myristate 13-acetate (PMA) and bryostatin, on the hydrolysis of phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) and on PtdCho synthesis. The cell lines used were selected because of their differential responses to protein kinase C activators and included rat-1 fibroblasts, untransformed and A-raf-transformed NIH 3T3 fibroblasts and human HL60 leukaemia cells. Exposure of rat-1 and NIH 3T3 fibroblasts to 100 nM-PMA stimulated phospholipase D-mediated hydrolysis of phospholipids about 2- and 6-fold respectively. In contrast, 100 nM-PMA had similar (2.5-3.0-fold) stimulatory effects on PtdCho synthesis in these cell lines. In the untransformed NIH 3T3 cells, both PMA and bryostatin stimulated both phospholipid hydrolysis and PtdCho synthesis, with 100 nM-bryostatin being somewhat less potent than 100 nM-TPA. In contrast, in A-raf-transformed NIH 3T3 cells or in HL60 cells, only TPA, but not bryostatin, stimulated PtdCho synthesis. In these transformed cells, bryostatin had 3-fold, or higher, stimulatory effects on phospholipid hydrolysis. Addition of ionomycin, a Ca2(+)-elevating agent, partially restored the stimulatory effect of bryostatin on PtdCho synthesis, but it failed to modify the effect of bryostatin on phospholipid hydrolysis. These data indicate that increased phospholipid hydrolysis is not necessarily associated with increased PtdCho synthesis.

Animals↗

PubMed1991

Membrane-associated phospholipase D activity in rat sciatic nerve.

Rat sciatic nerve contains a membrane-bound phospholipase D that catalyzes the hydrolysis of exogenous phosphatidylcholine (PC) to phosphatidic acid (PA) and choline. The enzyme is associated with a particulate fraction consisting primarily of microsomes and myelin. This fraction also contains phosphatidate phosphohydrolase activity leading to the production of diacylglycerols (DAG). The phosphohydrolase activity can be completely inhibited by NaF. Hydrolysis of exogenous PC requires detergent and is linear up to about 40 micrograms of protein at a pH optimum of 6.5. In the absence of NaF, the sum of PA and DAG increases linearly for 40 min, whereas in its presence, PA production is linear for only 15 min. At optimum conditions, PC hydrolysis proceeds at 15 nmol/h/mg of protein. Addition of increasing amounts of ethanol to the incubation system leads to the generation of increasing amounts of phosphatidylethanol, indicating transphosphatidylation activity. At an ethanol concentration of 0.4 M, phosphatidylethanol represents about one-half of the reaction products generated at approximately the same rate of enzymic activity observed in the absence of ethanol. Higher ethanol concentrations are inhibitory.

Animals↗

PubMed1990

Elevated levels of nonesterified fatty acids in the myocardium of alloxan diabetic rats.

Myocardial nonesterified fatty acids (NEFA) increase markedly within the first two days after the induction of insulin-dependent diabetes mellitus in rats by intravenous injection of alloxan. After initial variability, NEFA levels in diabetic hearts remain constant at approximately 450 nmol/g tissue (16 nmol/mumol lipid P), which is about three times higher than that in control hearts. Nonesterified linoleic acid is significantly increased in diabetic heart whereas both arachidonic and docosahexaenoic acids are decreased compared to controls.

Animals↗

PubMed1986

Concanavalin A-induced agglutination of Ehrlich ascites carcinoma cells during growth of the tumor in mice.

ConA-induced agglutination of Ehrlich ascites carcinoma (EAC) cells during development of the tumor in mice has been studied in vitro. EAC cells were incubated with different concentrations of ConA at 37 degrees C for various intervals of time and the cell aggregates of different sizes were scored under microscope. The older EAC cells (20-day-old) showed a decrease in cytoagglutination with respect to large aggregates formation compared to the younger (10-day-old) ones. The small aggregates formed by the 5-day-old EAC cells are dissociated by competition with alpha-methyl-D-mannoside but the large aggregates are not affected by the sugar treatment. The observed differences in the agglutination patterns are discussed in view of the influence of the lipid content of EAC cells and the ascites fluid on ConA-induced cytoagglutination.

Animals↗

PubMed1984

Purification and partial characterization of a murine mammary tumor-associated antigen.

A mammary tumor-associated antigen (MTAA) of the murine mammary tumor virus (MuMTV)-induced spontaneous mammary tumors of C3H/J mice was purified and partially characterized. The crude extract of the mammary tumor, when subjected to DEAE-cellulose chromatography and eluted with a discontinuous NaCl gradient, provided three major protein peaks, of which only the first (F1) possessed the MTAA activity. The antigen was further purified by subjecting F1 to polyacrylamide gel electrophoresis. The MTAA was a glycoprotein with a molecular weight of approximately 83,000. The antigen was localized in the plasma membrane and was different from the MuMTV structural antigens. Circulating antibodies against the MTAA were observed in the sera of tumor-bearing mice but not in that of tumor-free mice.

Animals↗

PubMed1984

Immunological relatedness of a murine mammary tumor-associated antigen and human breast cancer.

Immunological relatedness of a non-virion, murine mammary tumor-associated antigen (MTAA) and human breast cancer was demonstrated in this study. The MTAA was isolated from spontaneous mammary tumors (MMT) of C3H/J mice. An anti-serum specific for the MTAA was prepared by exhaustively absorbing the rabbit anti-serum to the MMT extract with tissue pellets of the pooled organs of tumor-free female mice. The observed cross-reaction of human malignant breast tumor (MBT) tissues with the absorbed antiserum further absorbed with normal human breast tissues suggested the presence of the MTAA or a related antigen in the MBT. No MTAA reactivity was found in human benign breast tumor. Circulating antibodies against the MTAA were recorded in all of 14 preoperative patients with MBT. Up to 18 months following surgical removal of the MBT, antibodies could be detected in the sera, though the reactivity was significantly lower than that of the sera of preoperative patients, and eventually disappeared. The antibodies were absent in patients with benign breast tumor and other neoplastic diseases, except in one patient with cancer of the cervix, and in healthy women.

Animals↗