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Biomedical subjects

K M Rao

Publications and source records attributed to K M Rao.

At least 37 records · Page 2Linked to original sources
PubMed1994

Increased adhesion of neutrophils to retinal vascular endothelial cells exposed to hyperosmolarity.

Recent studies suggest that leukocytes may contribute to capillary occlusion and endothelial cell injury in diabetic retinopathy. The present study is an attempt to determine whether high glucose concentration/hyperosmolar conditions would increase neutrophil adhesion to retinal endothelial cell monolayers. Confluent monolayers of bovine retinal endothelial cells were incubated for 24 hr in 96-well microtiter plates in 5.5, 20, 50 or 100 mM glucose using 20, 50 or 100 mM mannitol as osmotic controls. After 24 hr the cells were observed by phase microscopy, washed, and then incubated with isolated human neutrophils for 20 min. Non-adherent neutrophils were washed from the monolayers, and the number of adherent neutrophils was determined using an Elisa assay for neutrophil elastase. Adhesion of neutrophils to confluent monolayers of human umbilical vein and bovine aortic endothelial cells at all levels of glucose were assayed in a similar fashion for comparison. Neutrophil adherence to bovine retinal endothelial cells was significantly increased (P < 0.05, n = 8; paired t-test) at all elevated glucose concentrations compared with adherence at control (5.5 mM) glucose concentration. The effect was also concentration dependent with 20, 50 and 100 mM glucose resulting in 35, 57 and 70% increases respectively over controls. However, mannitol at equal concentrations produced similar increases in neutrophil adherence, indicating that the increases in adhesion caused by elevated glucose concentration were due to hyperosmolarity and not some special effect of glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Disulfiram lowers Ca2+, Mg(2+)-ATPase activity of rat brain synaptosomes.

The chronic administration of disulfiram (DS) to rats resulted in significant decrease of synaptosomal Ca2+, Mg(2+)-ATPase activity. In vitro studies indicated that DS (ID50 = 20 microM) produced a dose-dependent inhibition of Ca2+, Mg(2+)-ATPase. However, diethyldithio-carbamate, a metabolite of DS, failed to modify Ca2+, Mg(2+)-ATPase activity, implying that the decrease in ATPase activity in DS administered rats was due to the effect of parent compound. The DS-mediated inhibition (48%) of ATPase activity was comparable with a similar degree of inhibition (49%) achieved by treating the synaptosomal membranes with N-ethylmaleimide (ID50 = 20 microM) in vitro. Furthermore, the inhibition by DS was neither altered by washing the membranes with EGTA nor reversed by treatment with sulfhydryl reagents such as GSH or dithiothreitol. About 74% and 68% decrease of synaptosomal Ca2+, Mg(2+)-ATPase specific activity was observed when treated with DS (30 microM) and EGTA (100 microM) respectively. The remaining 25-30% of total activity is suggested to be of Mg(2+)-dependent ATPase activity. This indicates that both these drugs may act on a common target, calmodulin component that represents 70-75% of total Ca2+, Mg(2+)-ATPase activity. Therefore, DS-mediated modulation of synaptosomal Ca2+, Mg(2+)-ATPase activity could affect its function of maintaining intracellular Ca2+ concentration. This could contribute to the deleterious effects on CNS.

Animals↗
PubMed1994

Substance P and adrenocorticotropic hormone do not affect T-lymphocyte adhesion to vascular endothelium or surface expression of adhesion receptors.

Substance P (SP) and adrenocorticotropic hormone (ACTH) are peptides that have been shown to have both neurological and immunological effects. Because of the demonstrated effects upon immune function, we examined the effects of these peptides on T-lymphocyte adhesion to vascular endothelium and surface adhesion receptor expression. Neither the adhesion assays nor the expression assays showed any statistically significant effect of SP (10 microM) or ACTH (1 microM) for any incubation period used. We conclude that, while SP and ACTH have a variety of immunomodulatory effects, direct modulation of T-lymphocyte adhesion to vascular endothelium is probably not one of them.

Adrenocorticotropic Hormone↗
PubMed1994

Variability of plasma IL-6 and crosslinked fibrin dimers over time in community dwelling elderly subjects.

Because obtaining multiple blood samples from individuals involved in epidemiologic studies is difficult, conclusions must be drawn on the basis of one or two samples. In this study, the authors attempted to determine the variability of two plasma markers over time, namely IL-6 levels and crosslinked fibrin degradation products (D-Dimers), in 16 elderly community-dwelling individuals. The study group included both men and women and black and white subjects (four in each group). Eight blood samples were obtained from each subject over a period of 36 days. Blood was separated within 1 hour after collection and aliquots of plasma were stored at -70 degrees C until all samples were collected. All samples from an individual were analyzed at one time. IL-6 and D-Dimers were measured by commercially available ELISA kits. The variability in the levels of plasma IL-6 and D-Dimers was assessed by means of intra-class correlation coefficient (ICC). The estimates of the ICCs for one measurement of IL-6 and D-Dimers were .87 and .86, respectively. Reliability values of this magnitude indicate excellent reproducibility in the measurement. These values indicate that obtaining a single sample from a subject is fairly representative of that individual's IL-6 and D-Dimer levels over an extended period of time.

Activities of Daily Living↗
PubMed1994

Granulocyte deformability and F-actin content: relationship to diabetes mellitus and retinopathy.

Capillary closure in diabetic retinopathy may be initiated by lumenal occlusion by granulocytes. To determine whether subjects with diabetes mellitus have less deformable granulocytes than healthy subjects, granulocyte deformability was measured by mean entry time into a model capillary system in 16 diabetic-nondiabetic pairs. Granulocyte F-(filamentous) actin content between groups was compared, under basal conditions and after cellular stimulation. The relationship of granulocyte deformability to several diabetes-related variables was examined. Diabetic granulocytes were only 9% +/- 22% less deformable than normal granulocytes (p = 0.16). Deformability was increased in subjects with retinopathy and those with the worst glycemic control (r = 0.61, p = 0.026); both findings were in the opposite direction from that predicted. Basal and stimulated granulocyte F-actin content did not differ between the two groups (p > 0.2 for all assays). Although granulocytes may be important in the pathogenesis of diabetic retinopathy, granulocyte deformability (measured by mean entry time) and F-actin content are not significantly different between healthy patients and those with diabetes.

Actins↗
PubMed1994

Alterations in L-selectin expression and elastase activity in neutrophils from patients receiving granulocyte colony-stimulating factor alone or in conjunction with high-dose chemotherapy with autologous bone marrow transplantation.

We determined L-selectin expression and elastase levels in neutrophils obtained from patients receiving granulocyte colony-stimulating factor (G-CSF) either alone (given for increasing peripheral progenitor cells for harvest) or in combination with high-dose chemotherapy with autologous bone transplantation support (BMT). Administration of G-CSF alone for 3-5 days produced a decrease in L-selectin expression in neutrophils (25 +/- 4 versus 7 +/- 1, mean +/- SEM; mean channel fluorescence, n = 10) with no effect on neutrophil elastase activity (3.1 +/- 0.3 versus 3.4 +/- 0.6; micrograms elastase/million cells; n = 9). In contrast, in patients in the BMT group the L-selectin expression was increased (26 +/- 2 versus 38 +/- 3; n = 20) and elastase activity was markedly decreased (2.9 +/- 0.2 versus 1.4 +/- 0.2, n = 12) compared with values before BMT. The changes in L-selectin expression correlated with the ability of neutrophils to adhere to human umbilical vein endothelial cells. The decrease in the neutrophil elastase activity was not associated with an increase in the plasma elastase/alpha 1-antitrypsin complex levels, indicating that the decrease in the neutrophil elastase activity is not caused by activation of neutrophils and release of the enzyme into the plasma. Administration of G-CSF alone did not cause a decrease in the neutrophil elastase activity but increased plasma elastase/alpha 1-antitrypsin complex levels. There was no change in CR3 expression on neutrophils under any of these conditions. These observations suggest that the changes seen in neutrophils during BMT are influenced by various factors associated with BMT other than the administered cytokine alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Antineoplastic Agents↗
PubMed1994

Nutritional status of tribal preschool children in three ecological zones of Madhya Pradesh.

A health and nutrition survey was conducted on tribals in three ecological zones of Madhya Pradesh namely Jhabua (West Zone), Bastar (South Zone) and Sarguja (East Zone) taking into consideration the relative contribution of agriculture, forest and a combination of both to the economy, respectively. The consumption of both foods and nutrients appear to be worse among preschool children of Jhabua compared to Bastar and Sarguja. Clinically overt forms of Protein Energy Malnutrition and other vitamin deficiency signs were strikingly low. However, 4% of children in Sarguja exhibited signs of goitre. Both by extent and severity of malnutrition, the children of Jhabua appear to be worse followed by Bastar and Sarguja.

Anthropometry↗
PubMed1994

Mosquito repellency & toxicity of isomeric N, N-diethyltolylacetamides.

Three isomers of N, N-diethyltolylacetamides were synthesized and evaluated against Aedes aegypti and Culex quinquefasciatus for repellency and with mice for LD50, as an indicator of mammalian toxicity. Of these, N, N-diethyl-p-tolylacetamide (DEPTA) showed comparatively better repellency against C. quinquefasciatus. All the compounds showed higher repellency against C. quinquefasciatus than Ae. aegypti. In addition, N, N-diethyl-m-tolylacetamide (DEMTA) was found to be least toxic to mice.

Acetamides↗
PubMed1993

Age-related increase in phorbol myristate acetate-induced lymphocyte adhesion to vascular endothelium.

Lymphocyte adhesion to vascular endothelium is an important part of immune function. This investigation sought to detect differences between the adhesion of lymphocytes from young and aged human donors to vascular endothelium with and without treatment of the lymphocytes with phorbol myristate acetate (PMA), an activator of protein kinase C (PKC) that stimulates this adhesive process. T-lymphocytes were isolated from young and aged donors and adhesion assays were conducted with human umbilical vein endothelial cells (HUVEC). In some cases the HUVEC were activated by pre-incubation with tumor necrosis factor, a cytokine that increases their adhesiveness, before the addition of lymphocytes in the presence or absence of PMA. The results show that, in the basal state, lymphocytes from young and aged donors had similar levels of adherence, while with PMA activation, lymphocytes from aged donors had a significantly higher level of adherence to both activated and non-activated HUVEC. No cytotoxic effect on the HUVEC was detected. These results suggest a role for lymphocytes in diseases that predominantly affect the elderly and that are thought to involve interaction between lymphocytes and endothelium. In addition, these results indicate that there may be a change in PKC function in lymphocytes with aging.

Adult↗
PubMed1993

Diethylphenylacetamide: a new insect repellent against stable fly, Stomoxys calcitrans.

This paper reports the results of a laboratory study showing effectiveness of a new insect repellent N,N-diethylphenylacetamide (DEPA) against stable fly, Stomoxys calcitrans, and compared to N,N-diethyl-m-toluamide (DEET) and dimethyl-phthalate (DMP). DEPA gave maximum protection time of more than 6 h at 3% concentration followed by DEET and DMP.

Acetamides↗
PubMed1993

Medical education.

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Education, Medical↗
PubMed1992

Mutagenicity of N,N'-dimethylurea and methylamine hydrochloride in the Ames Salmonella/microsome test: absence of mutagenic response.

Methyl isocyanate (MIC) in aqueous solution forms methylamine (MA) and N,N'-dimethylurea (DMU). MA in buffered system further converts into its salt form, methylamine hydrochloride (MAH). Therefore, MAH and DMU were evaluated for their mutagenic activity in the in vitro Ames Salmonella/microsome mutagenicity test. The liquid preincubation protocol was followed, using tester strains TA98, TA100 and TA104 of Salmonella typhimurium, in the presence of 0, 5, 15 and 30% Aroclor 1254-induced rat liver S9 mixture. DMU and MAH did not induce a mutagenic response in any of the tester strains, both in the presence and in the absence of S9 mixture. The results therefore confirm that MIC in its native form or as its unknown metabolites is responsible for the mutagenic activity reported earlier by us in the his tester strains TA100 and TA104 of Salmonella typhimurium (Mutation Res., 204 (1988) 123-129) and not due to its hydrolysis products, MA or DMU.

Cyanates↗
PubMed1992

Cytochalasins induce actin polymerization in human leukocytes.

We studied the effect of cytochalasins (B, D, and E) on the F-actin content in human neutrophils and lymphocytes using NBD-phallacidin labeling followed by flow cytometry. All three cytochalasins induced a concentration- and time-dependent increase in the F-actin content in both cell types. The order of potency was cytochalasin D greater than E greater than B. The increase in F-actin content was accompanied by a decrease in the G-actin content as measured by DNase I inhibition assay. These observations suggest that in intact cells cytochalasins may function differently compared to purified and semipurified systems, and their effects may be modified through other actin-binding or sequestering proteins. 2-deoxyglucose (20 mM) caused a decrease in the basal F-actin content and significantly reduced the change induced by the cytochalasins. These results suggest that the state of actin in intact cells is regulated by cytosolic ATP levels, primarily by the integrity of the glycolytic pathway. Based on these observations, we conclude that the mechanism of action of cytochalasins in intact cells is more complex than current models suggest.

Actin Cytoskeleton↗
PubMed1992

Mutagenicity evaluation of riot control agent o-chlorobenzylidene malononitrile (CS) in the Ames Salmonella/microsome test.

o-Chlorobenzylidene malononitrile (CS), a riot control agent, was evaluated for its possible mutagenic activity in the Ames Salmonella/mammalian microsome mutagenicity test. Five histidine-deficient (His-) mutant tester strains of Salmonella typhimurium--TA97a, TA98, TA100, TA102 and TA104--were used. The liquid preincubation procedure was used with metabolic activation (presence of S9 mixture) and without metabolic activation (absence of S9 mixture). For the experiments with metabolic activation, three different concentrations of S9 fraction (supernatant of Aroclor 1254-induced rat liver homogenate at 9000 g)--5%, 15% and 30% in S9 mixture--were used. Along with mutagenic activity, CS was also evaluated for cytotoxic activity in all the five tester strains of Salmonella typhimurium, both in the presence and absence of S9 mixture. The mutagenic and cytotoxic activities of CS were assessed by counting the His+ revertant colonies and by counting the microcolonies (His-, auxotrophs in the background lawn), respectively, and the respective mean values were compared with the relative negative (solvent) control. A dose range of 12.5-800 micrograms plate-1 for CS did not induce a mutagenic response either in the presence or absence of S9 mix. No change in the negative mutagenic response of CS has been observed even in the presence of an elevated level of S9 fraction in the S9 mix. A dose of 200 micrograms plate-1 for CS was found to be cytotoxic by decreasing the surviving cells as well as His+ revertant colonies; however, the effect was reduced in the presence of an elevated level of S9 fraction in the S9 mix.

Animals↗
PubMed1992

Flow cytometric analysis of nitric oxide production in human neutrophils using dichlorofluorescein diacetate in the presence of a calmodulin inhibitor.

Dichlorofluorescein (DCFH) oxidation assay measures hydrogen peroxide (H2O2), which is a derivative of superoxide anion. We found that a calmodulin antagonist, W-13, which is known to inhibit superoxide anion generation enhanced the capacity of human neutrophils to oxidize DCFH. To investigate this discrepancy we studied the role of nitric oxide (NO) in DCFH oxidation. Pure NO was capable of oxidizing DCFH, and the product formed had spectral properties identical to oxidized DCFH produced by H2O2. The arginine analog, NG-monomethyl-L-arginine (NMMA), which inhibits NO production, in combination with W-13 completely inhibited the stimulus-induced increase in DCFH oxidation. We conclude that the oxidation of DCFH in human neutrophils can occur by either H2O2 or NO.

Arginine↗