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S Bala

Publications and source records attributed to S Bala.

18 recordsLinked to original sources
PubMed1992

Isolation of exfoliated colonic epithelial cells, a novel, non-invasive approach to the study of cellular markers.

Human stool is a heterogeneous mixture of non-digestible food residues, bacteria, cells exfoliated from the gastrointestinal mucosa and other secretory products. We have demonstrated that fresh human stools dispersed in a buffered saline solution can be fractionated over Percoll/BSA gradients to yield 9 discrete bands of cells in the density range of rho 1.033 to 1.139 and which could be further purified over Histopaque 1077. Enzyme-linked immunoassays (ELISA) for colon-specific antigen (CSA) and cytokeratins (CK) were positive. Western blot analysis showed the presence of 3 cytokeratin bands in the 40-kDa to 60-kDa range suggestive of cytokeratins 8, 18, and 19. Fluorescence flow-cytometric analysis of these cells using antibodies against CSA, CK, the blood-group antigens, carcinoembryonic antigen (CEA), non-mucus-secreting columnar-epithelium-specific MAb PR1A3, and to mucus-secreting colonic-epithelium-specific MAb PR5D5 showed varying degrees of reactivity. Expression of the blood-group phenotype suggests that cells from the proximal half of the colon had survived the transit, since in the adult expression of this marker is limited to cells from the proximal region of the colon. In this report we demonstrate the feasibility of studying, non-invasively, cell-specific markers on exfoliated cells isolated from stools. The evidence strongly suggests that almost all the cells are of colonic origin.

Antigens, Neoplasm↗
PubMed1992

Copper deficiency reversibly impairs DNA synthesis in activated T lymphocytes by limiting interleukin 2 activity.

The essentiality of adequate copper (Cu) nutriture for normal T-cell function in laboratory and domestic animals is well established. However, specific biochemical roles of Cu in the maturation and activation of T cells have not been defined. Previous work showed that when cultures of splenic mononuclear cells (MNCs) from Cu-deficient rats were exposed to T-cell mitogens, DNA synthesis was markedly reduced despite normal up-regulation of interleukin 2 (IL-2) receptors, transferrin receptors, and class II major histocompatibility complex molecules. In the present study, IL-2 activity in PHA-treated cultures of MNCs from Cu-deficient rats was 40-50% that of controls as determined by bioassay. Addition of rat IL-2 to phytohemagglutinin-treated cultures of MNCs from Cu-deficient rats increased blastogenic activity to control levels, demonstrating that Cu deficiency does not inhibit transition of quiescent cells to the competence phase of the activation process. Moreover, supplementation of MNC cultures from Cu-deficient rats with physiological levels of Cu enhanced IL-2 activity and DNA synthesis in response to phytohemagglutinin. These data indicate that IL-2 activity in cultures of activated splenic T lymphocytes from Cu-deficient rats is insufficient for optimal blastogenesis.

Animals↗
PubMed1992

A synthetic oligonucleotide probe (5'TTCCA 3')n uncovers a male specific hybridization pattern in the human genome.

A pentanucleotide motif 5'TTCCA3', originating from a 3.4 kb repeat fraction (DYZ1)1, is organized tandemly in the human genome. This motif is abundantly present on the long arm of the human Y (band Yq12) chromosome and is separated by Hae III digestion of male genomic DNA. We have developed a 20 base synthetic oligonucleotide probe, termed OAT20Y, comprising four repeat units of 5'TTCCA3', that uncovers a male-specific hybridization pattern in the human genome. The probe is highly sensitive, since less that 1 micrograms of DNA was sufficient to obtain visible signals after hybridization. Our results on discrimination of sex by using OAT20Y with several amniotic fluid samples was in accordance with clinical data. OAT20Y was found to be specific to the human genome as it did not hybridize with DNA of any non-human species. In addition to sexing human embryos in conjunction with severe X-linked genetic diseases, the probe may be useful in ascertaining the origin of tissues or blood samples in forensic cases.

Amniotic Fluid↗
PubMed1992

Effects of copper deficiency on T-cell mitogenic responsiveness and phenotypic profile of blood mononuclear cells from swine.

The effect of dietary copper deficiency on T-cell mitogenic responsiveness and phenotypic profile of blood mononuclear cells (MNC) in weaned pigs was examined. Outbred, weaned pigs were fed a semipurified diet containing adequate (6.4 mg/kg of body weight) or deficient (0.8 mg/kg) amounts of Cu. Pigs fed the low Cu diet for 10 weeks had markedly decreased concentrations of Cu in liver and plasma, and hypertrophic hearts. In vitro reactivity of MNC from Cu-deficient pigs to phytohemagglutinin and concanavalin A was significantly suppressed. This functional impairment was not associated with a decrease in the percentage of T cells, CD4 or CD8 cell subsets, or B cells. Expression of SLA-DQ and SLA-DR class II major histocompatibility complex (MHC) antigens was increased by Cu deficiency, the former significantly. Unlike rodents, in which inadequate Cu nutriture induces functional T cell deficiency that is associated with a decrease in the CD4 T-cell subset, swine fed inadequate Cu diets for 10 weeks had no changes in MNC subsets yet clearly manifested functional impairment of T-cell responses.

Animals↗
PubMed1992

Antimutagenic activity of Terminalia chebula (myroblan) in Salmonella typhimurium.

Antimutagenicity of water and chloroform extracts of dried myroblan Terminalia chebula was determined against two direct acting mutagens, sodium azide and 4-nitro-o-phenylenediamine (NPD) in strains TA100 and TA1535, and TA97a and TA98 of Salmonella typhimurium respectively and S9-dependent mutagen 2-aminofluorene (2-AF) in TA97a, TA98 and TA100 strains. Water extract reduced NPD as well as 2-AF induced his+ revertants significantly but did not have any perceptible effect against sodium azide included his+ revertants in TA100 and TA1535 strains of S. typhimurium. The pre-incubation studies, where the extract was incubated at 37 degrees C for 30 min with the said mutagen prior to plating, enhanced the inhibitory effect. Autoclaving the water extract reduced the inhibitory effect but the reduction in the effect was not significant. No inhibitory effect was observed in any of the strains and against any of the test mutagens with chloroform extract.

Chloroform↗
PubMed1991

Alterations in splenic lymphoid cell subsets and activation antigens in copper-deficient rats.

Rats were nursed by dams fed a diet containing adequate (6 micrograms/g) or deficient (0.6 micrograms/g) Cu during the lactation period and weaned to the same diet. Splenic mononuclear cells were isolated and the phenotypic profile determined by flow cytometry after immunolabelling with monoclonal antibodies to cell surface markers. Total splenic mononuclear cell yield and the relative percentage and absolute number of T-cells and the CD4+ (helper) and CD8+ (cytotoxic) T-subsets were decreased in Cu-deficient male rats. The relative percentage, but not the absolute numbers, of splenic B-cells and macrophages was increased by Cu deficiency. The percentage of splenic mononuclear cells from male rats that expressed interleukin-2 receptors and transferrin receptors in vivo was increased by Cu deficiency. In contrast, dietary Cu deficiency did not affect the yield and phenotypic profile of splenic mononuclear cells in female rats. Reactivity of splenic mononuclear cells to T-cell mitogens was decreased in Cu-depleted male and female rats. However, mitogen-induced increases in levels of interleukin-2 receptor and transferrin receptor were similar in cultures of splenic mononuclear cells obtained from control rats and rats subjected to restricted dietary intake of Cu only during the postlactation period. Thus, decreased mitogenic blastogenesis on exposure of cells from Cu-deficient rats does not reflect a nonspecific impairment of cellular activation.

Animals↗
PubMed1990

Determinants of OmpF porin antigenicity and structure.

Sixty-six murine hybridomas raised to Escherichia coli B/r porin were used to identify and differentiate the epitopes of this outer membrane protein. Anti-porin monoclonal antibodies (mAb) were raised against outer membrane fragments, purified native trimeric porin (trimer), and purified sodium dodecyl sulfate-denatured monomeric porin (monomer). Immunochemical and flow cytometric methods identified five distinct cell surface-exposed determinants on OmpF. The peptide composition of porin epitopes was determined by analysis of mAb reactivity with cyanogen bromide-generated peptide fragments. Four of 43 anti-monomer mAb reacted with surface exposed sites on OmpF, defining epitopes that consist of residues within CNBr peptides d2, d3, and B. The anti-porin mAb panel was also used to evaluate changes in porin antigenic structure in strains with short ompF deletions. Flow cytometric experiments indicated that despite changes in porin permeability, little if any alteration of surface epitopes occurred in these strains. Western immunoblot analysis of the mutant porins showed loss of reactivity with numerous mAb, which was caused by changes in three spatially distinct epitopes at residues 108-111, 118-123, and 124-129. Our findings indicate that in these ompF mutants the residues responsible for altering porin permeability are not exposed on the cell surface, but are buried within the tertiary structure of the protein. One of these regions, which is apparently involved in the determination of channel permeability characteristics, is conserved among 15 of 16 different porin molecules which were screened with the anti-OmpF mAb panel.

Amino Acid Sequence↗
PubMed1989

Antimutagenicity of some citrus fruits in Salmonella typhimurium.

The antimutagenic effect of 10 citrus fruit juices was observed against the mutagenicity of N-nitro-o-phenylenediamine (NPD) in TA97a and sodium azide in TA100 tester strains of Salmonella typhimurium using the Ames test. It was noticed that the juices of all these fruits reduced significantly the NPD and sodium azide induced revertant colonies. The inhibitory activity was enhanced if the mutagen and juice were co-incubated for about 30 min at 37 degrees C prior to performing the mutagenicity assay. Dilution with distilled water led to the reduction in the inhibitory activity. The antimutagenic activity of synthetic ascorbic acid or citric acid or combined ascorbic acid and citric acid was also seen. But the results with fruit juices tempted us to believe that in addition to ascorbic acid and citric acid, the presence of other factor(s) possessing antimutagenic properties cannot be ruled out.

Azides↗
PubMed1977

Population and family studies to demonstrate Ir genes: HLA haplotype in atopic allergy.

47 normal healthy controls and 45 atopic individuals together with five families with allergic diathesis and sensitive to mite antigen were typed for 13 HLA antigens. In general population, HLA-A1 and HLA-A8 were found to be higher than in normal controls. But the difference was significant at a level of p 0.05 after correction was made for the number of HLA antigens used. In one family, an HLA-A1 -B8 haplotype seems to be linked to the manifestation of atopic disease. The pattern of association of an HLA-A9 -B7 haplotype with the disease process in another family indicates that multiple genes may be involved in the manifestation of a variety of allergic disorders. Although more than one HLA haplotype of HLA-associated Ir gene for one antigen have been postulated, we still do not have enough evidence to suggest linkage between HLA haplotypes and atopic allergy. Further studies utilizing mixed lymphocyte culture and carefully matched control with a large number of subjects and more families are in progress to study the genetic basis of allergic diseases.

Asthma↗
PubMed1976

Effect of prolonged trifluoperazine, imipramine and haloperidol administration on serum cholesterol. An experimental study in rabbits.

As a result of prolonged intragastric administration of trifluoperazine (TFZ) and imipramine in rabbits, a significant rise in serum cholesterol was observed after 4, 8 and 12 weeks. Haloperidol was ineffective. Hypercholesterolemia produced by TFZ was not associated with increased estriol excretion in urine. Histochemical examination of aorta of TFZ-treated animals showed positive 'Schultz's reaction' for cholesterol, suggesting a possible causal relationship between TFZ-induced hypercholesterolemia and atherogenesis.

Animals↗