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Biomedical subjects

S Roy

Publications and source records attributed to S Roy.

At least 19 recordsLinked to original sources
PubMed1992

Reversible dimer dissociation of tubulin S and tubulin detected by fluorescence anisotropy.

Concentration-dependent dissociation of dimers of goat brain tubulin S and tubulin was studied by fluorescence anisotropy. Upon dilution, assembly-competent fluorescein 5'-maleimide labeled dimers of tubulin S and tubulin show a progressive decrease in fluorescence anisotropy. That this lowering of anisotropy results from the dissociation of tubulin S dimers into monomers was shown by dilution experiments with unlabeled homologous and heterologous proteins. A nonlinear least-squares fit of the data gave a dissociation constant of 7.1 x 10(-8) M for tubulin S compared to 7.2 x 10(-7) M for tubulin at 25 degrees C in 0.1 M PEM buffer, pH 7.0. van't Hoff plots of dimer-monomer dissociation of tubulin S and tubulin also show considerable differences in delta H and delta S. Effects of ionic strength and colchicine on the equilibrium constants are also substantially different for tubulin and tubulin S. The implications of these observations on the influence of C-terminal tails on tubulin structure are discussed.

Animals↗
PubMed1992

Malignant transformation by a mutant of the IFN-inducible dsRNA-dependent protein kinase.

The double-stranded RNA-dependent protein kinase (dsRNA-PK) is thought to be a key mediator of the antiviral and antiproliferative effects of interferons (IFNs). Studies examining the physiological function of the kinase suggest that it participates in cell growth and differentiation by regulating protein synthesis. Autophosphorylation and consequent activation of dsRNA-PK in vitro and in vivo result in phosphorylation of the alpha subunit of eukaryotic initiation factor-2 (eIF-2) and inhibition of protein synthesis. Expression of a functionally defective mutant of human dsRNA-PK in NIH 3T3 cells resulted in malignant transformation, suggesting that dsRNA-PK may function as a suppressor of cell proliferation and tumorigenesis.

Amino Acid Sequence↗
PubMed1992

Immunobiological studies on experimental visceral leishmaniasis. II. Adherent cell-mediated down-regulation of delayed-type hypersensitivity response and up-regulation of B cell activation.

Visceral leishmaniasis or kala-azar is characterized by a variety of immunopathological consequences in man. The most remarkable of these are the depression of cell-mediated immunity and polyclonal B cell activation. The consequences observed in man could be induced in a murine model by inoculating the causative agent, Leishmania donovani. The cell-mediated response was studied in this murine model in terms of the delayed-type hypersensitivity (DTH) response toward leishmania antigen in a progressive infection. BALB/b (H-2b) mice showed progressive enhancement in the DTH response, whereas BALB/c (H-2d) mice showed strong DTH at the onset which gradually disappeared (defined as DTH-negative phase) and reappeared again at the later stage of infection. Adoptive transfer of enriched populations of splenic T cells from infected BALB/c mice together with parasite antigen into the footpad of syngenic normal recipients produced a dramatic enhancement in the DTH response, except at the onset of the DTH-negative phase. These observations indicate that adherent cells have a role in suppression of the cell-mediated immune response and also that another mechanism operates at the onset of the DTH-negative phase. This DTH-negative phase was not caused by depletion of DTH-mediating cells from the repertoire, but rather by suppression mediated by a subset of T cell evolved in the course of infection. Characterization on the basis of lymphokine production of the T cells mediating the DTH response and of T cells mediating suppression of the DTH response showed them to be of Th1 and Th2 type, respectively. Studies also indicated that at the onset and the later stages of infection suppression was mediated by adherent cells, but at the onset of DTH-negative phase, in particular, suppression was mediated by Th2 cells. Furthermore, experiments also showed that adherent cells from infected mice gained another property, that of driving B cells, in a T cell-dependent manner.

Animals↗
PubMed1992

The prevalence of diagnosed systemic lupus erythematosus in whites and Indian Asian immigrants in Leicester city, UK.

The prevalence of diagnosed systemic lupus erythematosus (SLE) during 1989 in the adult Indian Asian and White populations of the city of Leicester has been determined. Fifty cases (19 Asian, 31 White) fulfilling the 1982 revised ARA criteria for SLE were identified from a population of 191,469 (37,684 Asian, 153,785 White). Five different sources were used to ascertain cases. The overall prevalence of SLE in Whites was 20.2 per 100,000. Asians of both sexes had a significantly higher prevalence than Whites. Prevalence in males was 31.5 and 7.0 per 100,000 in Asians and Whites respectively; in females the figures were 69.7 and 31.7 per 100,000. Overall, lupus was 3.0 times more common in Asians than Whites. This is the first prevalence study of SLE in Indian Asians and suggests that, like the Black races and the Chinese, they have a greater frequency of SLE than Whites.

Adult↗
PubMed1992

The possible inhibitory role of the leucine-zipper DNA binding protein c-fos in the regulation of hepatic gene expression after sepsis.

BACKGROUND: The leucine-zipper c-fos has been implicated in the regulation of gene expression. We investigated the possible role of c-fos in the regulation of hepatic gene expression after sepsis. Based on previous data demonstrating that sepsis inhibits hepatic gene expression of carnitine palmitoyltransferase (CPT), we hypothesized that c-fos may play a role in the inhibition of CPT gene expression after sepsis. METHODS: We studied c-fos gene expression after peritoneal sepsis induced by cecal ligation and puncture (CLP) or sham-CLP. To investigate the possible inhibitory role of c-fos on CPT gene transcription, we investigated the effect of c-fos on c-jun-driven CPT promoter-chloramphenicol acyltransferase reporter gene expression in a HepG2 hepatoma cell cotransfection model. To investigate the possible role of cyclic adenosine monophosphate (cAMP) in the regulation of c-fos in vivo, we treated either the sham-CLP group or the CLP group with either vehicle or cAMP. RESULTS: Peritoneal sepsis in the rat model resulted in a four-fold increase in hepatic c-fos mRNA and c-fos protein. In the cotransfection model, c-fos significantly inhibited c-jun-induced chloramphenicol acyltransferase activity. Treatment with cAMP resulted in a 50% decrease in c-fos protein in either the sham-CLP or CLP group. CONCLUSIONS: We conclude that (1) sepsis increases hepatic c-fos transcription and translation, (2) c-fos inhibits c-jun-induced CPT gene expression, and (3) cAMP probably does not directly mediate the increase in c-fos after sepsis.

Animals↗
PubMed1992

Characterization of [3H]morphine binding to interleukin-1-activated thymocytes.

We have previously reported that interleukin-1-induced proliferation of thymocytes is accompanied by the appearance of [3H]morphine binding sites on these cells. In the present study, we have characterized these binding sites. They differ from classical opioid receptors in the brain in several ways, including: 1) lack of stereoselectivity; 2) relatively low affinity (Kd = 50 nM) and high capacity (Bmax = 3 pmol/mg of protein); 3) binding is strongly inhibited by Ca++, Mg++, Mn++ and Cl- ions and 4) binding is inhibited by proteinase K or E and by phospholipase A2 but not trypsin treatment of thymocyte membranes. The binding sites, which were found largely on the CD4+ subset of T-cells, also showed a preference for opioid alkaloids over peptides. These [3H]morphine binding sites may mediate a negative feedback effect on interleukin-1-induced proliferation of thymocytes in vivo.

Animals↗
PubMed1992

Neurological findings in HIV-infected children: a review of 49 cases.

Many HIV-infected children have neurological involvement. We present our observations in 49 cases, 58% of which had some form of clinical neurological impairment. Most of the patients affected (71%) presented with progressive encephalopathy, characterized by developmental delay with loss of acquisitions and cognitive decline, an impaired growth curve, microcephaly and corticospinal dysfunction. CT-scan imaging shows cerebral atrophy in all cases and basal ganglia calcifications in 29%. Non-specific abnormalities are found on the EEG in two-thirds of cases and in the CSF in slightly less than half the cases. Pathological studies sometime revealed HIV encephalitis or lateral corticospinal tracts degeneration. Neurological impairment secondary to vascular events, neoplasms or opportunistic infections were rare, especially when compared with the adult HIV population.

AIDS Dementia Complex↗
PubMed1979

"Incessant ovulation" and ovarian cancer.

A case-control study of 150 ovarian cancer patients under the age of 50 and individually matched controls was done to study the influence of fertility and oral contraceptive use on the risk of ovarian cancer. The risk decreased with increasing numbers of live births, with increasing numbers of incomplete pregnancies, and with the use of oral contraceptives. These three factors can be amalgamated into a single index of protection--"protected time"--by considering them all as periods of anovulation. The complement of protected time--viz., "ovulatory age", the period between menarche and diagnosis of ovarian cancer (or cessation of menses) minus "protected time"--was strongly related to risk of ovarian cancer. Other factors found to be associated with increased ovarian cancer risk were obesity, cervical polyps, and gallbladder disease. Women who had an "immediate" intolerance to oral contraceptive use had a fourfold increased risk of ovarian cancer. 7 patients, but no controls, could recall a family history of ovarian cancer.

Abortion, Spontaneous↗
PubMed1979

Comparison of three different models of the copper T intrauterine contraceptive device.

A random sequential comparative study of three models of the Copper T intrauterine contraceptive device (IUD) was undertaken in 1,792 women. For 7 months, the TCu 300 and TCu 220C were randomly inserted, and then the TCu 380A and 220C were randomly inserted for the next 12 months. The log-risk method of life-table analysis of event rates was performed at the end of each of the first 3 years of use of each device. The TCu 380A had the lowest pregnancy rate during each year of use, although the difference was not significant. At the end of each of the first 2 years, the TCu 300 was removed significantly less than the TCu 220C and TCu 380A for bleeding and pain. At the end of three years, the rates of removal for bleeding and pain for the TCu 380A and TCu 300 were similar and lower than that for the TCu 220C, but the overall difference was not significant. There were no differences among the devices for any other relevant use-related reasons. The TCu 380A was removed for other medical reasons significantly more frequently than the other devices at the end of 2 and 3 years. Adjusting for parity did not alter the results. The findings of this study suggest that the copper sleeves along the horizontal arms together with copper wire on the vertical arm in the TCu 380A model provide greater protection against intrauterine pregnancy, whereas the copper sleeves along the vertical arm as in the TCu 220C caused increased removals for bleeding and pain. The TCu 380A should be studied in a larger number of patients for a longer period of time to determine its clinical effectiveness. It may become the IUD of choice for all women irrespective of parity.

Female↗
PubMed1979

A comparison of clindamycin-gentamicin and penicillin-gentamicin in the treatment of post-cesarean section endomyometritis.

A random comparison of clindamycin-gentamicin (C-G) and penicillin-gentamicin was made in 200 women who developed endomyometritis following cesarean section. All pretreatment profiles indicated similar populations. The clinical response was more favorable in the women receiving clindamycin-gentamicin. The implications of these results upon clinical practice is discussed.

Adult↗
PubMed1979

Familial transmission of preauricular fistula in a seven generation Indian pedigree.

Familial occurrence of fistula auris congenita (ear pits) is described in a Muslin kindred of Indian origin. The pedigree was traced through seven generations. The abnormality appeared in sixty individuals comparising equal number of males and females. No sexual dimorphism was indicated in the expression of the trait, which occurred bilaterally as a small pit just anterior to the crus at the root of the ascending helix. The abnormality was found to be inherited through an autosomal dominant gene with incomplete penetrance. The expression of the trait does not show any dosage effect.

Consanguinity↗