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Biomedical subjects

S Chatterjee

Publications and source records attributed to S Chatterjee.

At least 289 records · Page 16Linked to original sources
PubMed1993

Exorbitantly enhanced protein gyration and erroneous membrane modification programs in spermatozoa after vasectomy: a biophysical basis for low infertility revival after vasectomy.

Vasectomy induces an immediate biophysical incompetence in epididymal spermatozoa in terms of the erroneous execution of membrane configuration processes, premature membrane melting and untimely protein gyration. Disturbances in the planned expression 'foreign proteins' and the possible 'swinging off' of these molecules from the membrane crystals might tease the immune system and might deprive the spermatozoa of the essential recognizing terminals.

Animals↗
PubMed1993

Folding pathway mediated by an intramolecular chaperone.

The N-terminal propeptide of subtilisin, a serine protease, functions as an intramolecular chaperone which is crucial for proper folding of the active enzyme. This nascent N-terminal propeptide is removed after completion of the folding process. Here we present a possible pathway by which intramolecular chaperones mediate protein folding. Using circular dichroism to analyze acid-denatured subtilisin we have identified a folding-competent state which can refold to an active conformation in the absence of the propeptide. Earlier work had shown that guanidine hydrochloride-denatured subtilisin was in a state incapable of folding in absence of its propeptide. Comparison of the folding-incompetent and folding-competent states indicates that refolding is facilitated by the presence of residual structure present only in the folding-competent state. The analysis further indicates that the propeptide is essential for inducing this state. Therefore the folding-competent state may lie on--or be in rapid equilibrium with an intermediate on--the folding pathway of subtilisin. In the absence of the propeptide, formation of such a state--and hence refolding--is extremely slow.

Amino Acid Sequence↗
PubMed1993

Regulation of synthesis of lactosylceramide in normal and tumor proximal tubular cells.

We have measured the binding and degradation of low-density lipoprotein (LDL) and LDL-mediated effects on cholesteryl ester (CE) synthesis in cultured normal and tumor proximal tubular (PT) cells. The effects of LDL on the regulation of glycosphingolipid metabolism in cells was pursued employing radioactive precursors, e.g., [3H]serine, and [3H]glucose and by measuring the activity of UDP-galactose: glucosylceramide: B1-4 galactosyltransferase (GalT-2). In normal PT cells, there was a saturable and displaceable binding and degradation of 125I-LDL and a LDL mediated 14-fold stimulation of cholesteryl ester (CE) synthesis. This was accompanied by a suppression (70-80%) of incorporation of [3H]glucose and [3H]serine into GlcCer, LacCer, GbOse3Cer and GbOse4Cer and suppression (70-80%) of GalT-2 activity. In tumor PT cells, displaceable binding and degradation of 125I-LDL was not observed and LDL failed to stimulate CE synthesis. In such cells, LDL exerted a concentration-dependent stimulation of [3H]glucose and [3H]serine incorporation into GSL. Maximum stimulation (250%) of GalT-2 activity in tumor PT cells occurred with 25 micrograms LDL/ml medium. We conclude that LDL taken up via receptor mediated pathway decreases GaIT-2 activity in normal PT cells. In contrast, LDL not taken up via the LDL receptor pathway in tumor PT cells failed to suppress the incorporation of [3H]glucose and [3H]serine into glycosphingolipids and GalT-2 activity leading to a stimulation of lactosylceramide synthesis.

Antigens, CD↗
PubMed1993

Neutral sphingomyelinase increases the binding, internalization, and degradation of low density lipoproteins and synthesis of cholesteryl ester in cultured human fibroblasts.

I have investigated the effects of human urinary neutral sphingomyelinase (N-SMase) (Chatterjee, S., and Ghosh, N. (1989) J. Biol. Chem. 264, 12554-12561) on the cell-surface binding, internalization, and degradation of 125I-low density lipoprotein (LDL) and on cholesteryl ester synthesis in cultured human fibroblasts. N-SMase exerted a concentration-dependent continuous stimulation of 125I-LDL cell-surface binding, internalization, and degradation in normal human fibroblasts. A 3-fold increase in binding, internalization, and degradation was observed at the maximum amount (600 units of N-SMase/ml) examined. This phenomenon was accompanied by a continuous stimulation of cholesteryl ester synthesis. A 5-fold increase in cholesteryl ester synthesis was observed after incubation for 4 h with N-SMase. Antibody against N-SMase and heat inactivation of N-SMase compromised the stimulatory effects of N-SMase on 125I-LDL metabolism and cholesteryl ester synthesis in these cells. Incubation of cells with phospholipase D and phospholipase C did not alter 125I-LDL binding, internalization, or degradation. This finding suggests that the stimulatory effects of N-SMase on LDL metabolism and on cholesteryl ester synthesis in fibroblasts is specific. Moreover, unlabeled LDL competitively displaced 125I-LDL from binding to N-SMase-treated cells. None of the precursors of sphingomyelin could mimic the stimulatory effects of N-SMase on 125I-LDL metabolism in these cells. Taken together, these studies suggest that one of the biological roles of N-SMase involves modulating LDL metabolism and cholesterol metabolism in fibroblasts.

Cells, Cultured↗
PubMed1993

Phagocytic activity of Dictyostelium amoebae treated with an organochlorine pesticide.

The effect of an organochlorine pesticide benzene hexachloride (containing alpha, beta, gamma and delta isomers) on the phagocytic activity of the vegetative cells of Dictyostelium discoideum was investigated. Benzene hexachloride (BHC) at concentrations of 60 ppm and above inhibited the phagocytic activity as revealed by 3H-labelled E. coli uptake. The BHC treated cells also showed smaller and delayed plaque formation. Interactions of lipophilic pesticide with the hydrophobic cell surface presumably alters the receptor mediated phagocytosis of Dictyostelium amoebae.

Animals↗
PubMed1993

Contrasting action of antiestrogen (ICI-182780) for preventing initiation of embryo implantation by estradiol or epidermal growth factor (EGF).

The pure estrogen antagonist ICI-182780, at doses above 50 micrograms/kg, effectively inhibited the initiation of embryo implantation in rats when administered on day 4 of pregnancy (day 1 = sperm positive). The same dose inhibited the implantation initiating effect of intravenous 25 ng of estradiol-17 beta in delayed implanting progesterone-primed hypophysectomized rats. In contrast, the anti-estrogen at a dose of 1 mg/kg was ineffective at inhibiting the initiation of implantation induced by intrauterine plus intravenous administration of murine epidermal growth factor to delayed implanting rats. The growth factor also initiated implantation of blastocysts transferred from donor animals injected with the anti-estrogen to progesterone-primed hypophysectomized recipients. The results clearly demonstrate that the implantation initiating effect of the growth factor is not inhibited by a pure estrogen antagonist, and therefore this estrogenic function does not appear to require action initiated by the classical estrogen receptor.

Animals↗
PubMed1993

Antiviral effect of the extract of culture medium of Lentinus edodes mycelia on the replication of herpes simplex virus type 1.

An extract of culture medium of Lentinus edodes mycelia, JLS-S001, significantly blocked the release of infectious herpes simplex virus type 1 (HSV-1) from African green monkey kidney cells. The block in replication was not due to the effect of JLS-S001 on the adsorption and penetration of HSV-1 to the monkey kidney cells. This observation was supported by the fact that JLS-S001 had no significant effect on the expression of virus-specific nucleocapsid proteins in the treated cells. Furthermore, electron microscopy demonstrated the presence of nucleocapsids within the nuclei of the infected and JLS-S001-treated cells. However, the expression of glycoproteins B, C, D, E and I was reduced in the JLS-S001-treated cells. These results suggested that JLS-S001 blocked HSV-1 replication at a late stage in virus replication cycle probably in the assembly and budding of nucleocapsids and subsequent egress from the treated cells.

Adsorption↗
PubMed1993

The backbone structure of the major cold-shock protein CS7.4 of Escherichia coli in solution includes extensive beta-sheet structure.

CS7.4 is the major cold-shock protein specifically expressed to a level as high as 13% of the total cellular protein within the first hour when Escherichia coli cell culture is shifted from 37 to 15 degrees C [Goldstein et al. (1990) Proc. Natl. Acad. Sci. USA 87, 283-287]. It consists of 70 amino acid residues with a very high content of aromatic residues. CS7.4 was overproduced and purified to homogeneity. Its secondary structure was analyzed by examining circular dichroism at both the far and near-UV regions; the results suggest that the protein is largely beta-sheet in conformation. The predominance of beta-sheet structure in the protein was confirmed by using Fourier-transform infrared spectroscopy. A folded compact conformation was also verified by fluorescence emission spectroscopy. We evaluated Tm, delta H, and delta S from the thermal denaturation profile of the protein. Unusual spectral features observed in the far-UV region are attributed to the high content of aromatic residues. The protein is relatively small and contains no disulfide bonds. However, it is surprisingly stable to heat denaturation.

Bacterial Proteins↗
PubMed1993

Synthetic peptides based on conserved Plasmodium falciparum antigens are immunogenic and protective against Plasmodium yoelii malaria.

Two synthetic polypeptides containing multiple B- and T-cell epitopes derived from the conserved regions of two vaccine candidate antigens namely MSA-1 and RESA of human malarial parasite P. falciparum were studied for immunogenicity and protectivity. Both constructs elicited strong antibody and lymphocyte proliferation responses in BALB/c mice immunized with the carrier-free peptides. In an ELISA, these peptides also bound antibodies present in the sera from the P. vivax infected humans as well as from the P. yoelii infected mice. Significantly, our data showed that immunization of mice with these P. falciparum peptide could impart partial protection against P. yoelii challenge infection. Our finding that synthetic peptides representing portions of P. falciparum antigens were capable of stimulating protective immune responses against rodent malaria suggests that murine malaria model P. yoelii may provide a suitable system for primary screening of potentially protective synthetic immunogens.

Amino Acid Sequence↗
PubMed1993

Effect of continuous slow-speed running for 12 weeks on 10-14-year-old Indian boys.

Endurance training was conducted on a group of 41 East Indian boys aged 10-14 years and was compared with 25 untrained boys of the same age. A continuous slow-running method was adopted for 12 weeks. The intensity of the training was 80-85% of maximum heart rate and frequency was 3 days per week. The boys were trained for a 1500-m event and therefore they covered three to five times their racing distance. For psychological reasons the training was carried out in a playground. The investigations included different physical and motor fitness tests: measurement of flexibility, agility, speed, leg muscle strength etc. Their performance times were also recorded before and after training. From statistical analysis we concluded that this particular type of training programme did not produce any detrimental effects on 10-14-year-old boys. On the other hand, this type of training did have some influence on improving physiological parameters in this age group of boys when compared with untrained boys of the same age.

Adolescent↗
PubMed1993

Subclinical hypothyroidism: a determinant of polycystic ovary syndrome.

The present study was an endeavor to explore whether and how hypothyroidism plays a role in the etiology of polycystic ovarian syndrome (PCOS). A composite picture of the hormone profile was assessed in different groups of subjects (control women and hypothyroid women with or without PCOS). Comparative analysis of the results suggests that hypothyroidism is invariably followed by a lowering of sex hormone binding globulin and an increment in the free testosterone level, but further metabolism of testosterone (T) may or may not be directed towards an overproduction of estriol (E3). The factors that dictate the route of T metabolism, and the way by which E3 acts to rescue the ovaries from the development of PCOS under the hypothyroid state are discussed.

Adult↗
PubMed1993

Replication, establishment of latency, and induced reactivation of herpes simplex virus gamma 1 34.5 deletion mutants in rodent models.

Previous studies have shown that a gene mapping in the inverted repeats of the L component of herpes simplex virus, type 1 DNA, designated as gamma (1) 34.5, was dispensable for growth in cells in culture but that the deletion mutant (R3616) and a mutant containing a stop codon (R4009) in each copy of the gene were incapable of replicating in the central nervous systems (CNS) of mice. Restoration of the deleted sequences restored the wild type virus phenotype. We report here that the gamma (1) 34.5 mutant viruses (R3616 and R4009) replicated in the vaginal tract of two different strains of mice and guinea pig, although both viruses were shed at lower titer and for fewer days than the wild type and restored viruses. Both R3616 and R4009 failed to replicate or cause significant pathology in the cornea of Balb/C mice or following intranasal inoculation of Swiss Webster mice. Analyses of sensory trigeminal and dorsal root ganglia innervating the site of inoculation indicated that the incidence of establishment of latency or reactivation from latency by R3616 and R4009 viruses was significantly lower than that determined for mice infected with wild type or restored virus. Thus, selective deletion of gamma (1) 34.5 gene abolished the capacity of the virus to spread from peripheral mucosal sites to the CNS or replicate in the CNS, and diminished the capacity of the virus to replicate at mucosal sites and, subsequently, establish latency, or be able to be reactivated ex vivo. The results of our studies may have direct implications for the development of genetically engineered herpes simplex virus vaccines.

Animals↗
PubMed1993

Embryo implantation in the rat uterus induced by epidermal growth factor.

The present study was undertaken to determine whether the mechanism of embryo transfer is a factor in the action of epidermal growth factor (EGF) in initiation of implantation. Unilateral intrauterine infusion of 3 microliters buffered saline, or saline containing 1.5 micrograms EGF, plus i.v. injection of 100 micrograms EGF 2 h later resulted in implantation sites in all animals within 48 h. In several animals implantation was also initiated in the non-injected uterine horn. Administration of indomethacin 1 h before the intrauterine injection completely blocked the effect of EGF but not that of 25 ng oestradiol. The results confirm that EGF can replace oestrogen for initiation of implantation provided that the uterine trauma associated with embryo transfer, that is puncture, is provided. The mechanisms involved remain to be resolved.

Animals↗
PubMed1993

Intra-diploic meningioma in a child.

Few cases of intra-diploic meningiomas have been described in the literature. We report a case which is unusual in that it occurred in a child of 15 years of age.

Adolescent↗
PubMed1993

Prediction of recurrence in pituitary tumours: a flow cytometric study using in vivo bromodeoxyuridine.

Although most pituitary tumours are regarded as benign, there is a significant risk of local recurrence and a few are frankly malignant. The prediction of clinically aggressive behaviour by histopathological means is inadequate and the selection of patients for postoperative radiotherapy has often been empirical. The flow cytometric analysis of the DNA content of certain intracranial tumours has suggested a correlation between a high proliferative index and a tendency to recur. The in vivo administration of bromodeoxyuridine (BUdR) yields a reliable and accurate S-phase labelling index and evaluation by flow cytometry allows a much greater and therefore more representative number of cells to be examined. We report our results for the flow cytometric evaluation of the S-phase fraction in a group of 11 human pituitary tumours following the preoperative administration of BUdR and discuss the correlation between high values of S-phase fraction and clinically aggressive behaviour. Initial results suggest a correlation between radiological evidence of tumour invasion and an S-phase greater than 2%.

Adenoma↗