Biomedical subjects

S Agarwal

Publications and source records attributed to S Agarwal.

At least 289 records · Page 16Linked to original sources

PubMed1990

Membrane lipid peroxidation by UV-A: mechanism and implications.

UV-A produced a dose-dependent linear increase of lipid peroxidation in liposomal membrane, as detected by the assay of (i) conjugated dienes, (ii) lipid hydroperoxides, (iii) malondialdehydes (MDA), and (iv) the fluorescent adducts formed by the reaction of MDA with glycine and also a linear dose-dependent increase of [14C]glucose efflux from the liposomes. UV-A-induced MDA production could not be inhibited by any significant degree by sodium formate, dimethyl sulfoxide, EDTA, or superoxide dismutase but was very significantly inhibited by butylated hydroxytoluene, alpha-tocopherol, sodium azide, L-histidine, dimethylfuran, and beta-carotene. MDA formation increased with an increase in the D2O content in water, leading to a maximal amount of nearly 50% enhancement of lipid peroxidation in 100% D2O vis-à-vis water used as dispersion medium. The experimental findings indicate the involvement of singlet oxygen as the initiator of the UV-A-induced lipid peroxidation.

Antioxidants↗

PubMed1990

Tendinitis and tendon ruptures in successful renal transplant recipients.

The musculoskeletal system of 167 successful renal transplant recipients was examined for locomotor complications. Apart from avascular necrosis and spontaneous fractures, two new clinical entities were identified: tendinitis and spontaneous tendon ruptures. Tendinitis was found in the supraspinatus and calcaneal tendons in 12 patients (7.2%). Pretransplant hyperphosphatemia and posttransplant hypercalcemia were seen in patients developing tendinitis. Spontaneous tendon ruptures were observed in the calcaneal tendons in four patients (2.4%). Pretransplant hyperphosphatemia was observed in this group of patients. The cumulative dose of prednisolone was not significantly different than in asymptomatic patients.

Adolescent↗

PubMed1990

The effect of serum from patients of chronic renal failure on colony forming units (CFU-S) in mice.

Repopulating ability of mouse bone marrow stem cells, treated with pre-dialysis, post-dialysis and control sera was assessed by colony forming units (CFU-S). Significant lower colony counts were observed in pre-dialysis group as compared to control group. There was an improvement in the colony counts when the cells were treated with post-dialysis sera. The study suggests the presence of inhibitor/s of CFU-S in the uraemic sera which is/are partially removed by haemodialysis.

Adult↗

PubMed1989

UV-A induced lipid peroxidation in liposomal membrane.

UV-A (365 nm) produced a dose-dependent linear increase of lipid peroxidation, as detected by the assay of malondialdehyde (MDA). MDA formation was inversely related to the UV-A dose rate. Sodium formate and ethylenediaminetetra acetic acid (EDTA) could not inhibit by any significant degree the UV-A induced MDA formation. While butylated hydroxy toluene (BHT) caused about 85% inhibition, sodium azide and L-histidine produced 45-50% inhibition of MDA formation. The involvement of singlet oxygen (1O2) in the UV-A induced lipid peroxidation is discussed.

Free Radicals↗

PubMed1989

Altered free cytosolic calcium changes and neutrophil chemotaxis in patients with juvenile periodontitis.

Nearly 70-75% of patients with localized juvenile periodontitis (JP) have abnormal polymorphonuclear leukocytic (PMN) chemotaxis. The objective of this study was to determine whether the lower chemotactic response in PMNs from JP patients is associated with a defect in intracellular signal transduction, as measured by stimulus-induced changes in free cytosolic calcium (Ca2+) mobilization. We report that peptide chemoattractants such as N-formyl-methionyl-leucyl-phenylalanine (fMLP) and the complement fragment C5a in direct comparative studies induced lower amounts of initial Ca2+ mobilization in PMNs from JP patients than healthy controls, as monitored by intracellular fura-2 fluorescence. The initial resting levels of free cytosolic Ca2+ in PMNs from JP patients and normal individuals were found to be similar. fMLP and C5a both mobilized Ca2+ in PMNs in a dose-dependent manner. Treatment of PMNs from 0.16 to 20 nM fMLP and 0.2 to 20 nM C5a resulted in elevated levels of free cytosolic Ca2+. However, above 20 nM fMLP and 5 nM C5a concentrations the extent of total Ca2+ mobilization did not differ significantly. Although fMLP and C5a caused Ca2+ mobilization in PMN cells from JP and healthy control subjects, fMLP stimulation induced higher levels of free cytosolic Ca2+ mobilization in PMN cells from healthy control subjects (141.29 +/- 25.55 nM/2 x 10(6) PMNs), than PMNs from JP patients (62.33 +/- 23.76 nM/2 x 10(6) PMNs). Similarly C5a induced higher levels of Ca2+ mobilization in PMNs from healthy control individuals (130.43 +/- 18.26 nM Ca2+/2 x 10(6) PMNs)O, when compared to JP patients (49.92 +/- 14.92 nM Ca2+/2 x 10(6) PMNs).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1989

Clinical and laboratory characterization of early onset periodontitis.

Clinical and laboratory data were compared in 72 patients with localized periodontitis (LP) and 103 patients with generalized periodontitis (GP). Significantly more LP than GP cases had decreased neutrophil chemotaxis (CTX), and were seropositive for Actinobacillus actinomycetemcomitans (Aa). Significantly, more GP cases were seropositive for Bacteroides gingivalis (Bg). All clinical indices were similar on affected teeth in LP and GP, but the attachment loss was greater on clinically unaffected teeth in GP when compared with LP. LP cases with CTX defects had a significantly lower mean age, were more often seropositive for Aa antibodies, and were more often female than LP patients with normal CTX. Significantly more GP cases with CTX defects were seropositive for Aa antibody. GP patients with normal CTX had a higher plaque index on both affected and unaffected teeth than did GP patients with a CTX defect. Our data suggest that chemotaxis and/or specific bacteria may be contributory, but not always necessary, factors in these disorders. The overlap in clinical and laboratory profiles of LP and GP continues to cloud the distinction of these early onset forms of periodontitis.

Adolescent↗

PubMed1989

Histopathological study of xanthogranulomatous cholecystitis.

A total of 418 gallbladders removed surgically as chronic cholecystitis or carcinoma gallbladder were studied retrospectively for the presence of xanthogranulomas which were found in 45 (10.8%). The age of patients with xanthogranulomatous cholecystitis ranged from 15 to 80 yr with a mean of 45.3 indicating an early presentation of the disease in our population. The male to female ratio was 1:8. The gallbladder was invariably thickened and calculi of cholesterol or mixed type were present in all cases. Xanthogranulomatous foci appeared as yellowish nodules 2-15 mm in size, on the mucosal surface. In some gallbladders, the involvement was diffuse and these foci extended to the surrounding structures. Histologically, xanthogranulomas encompassed the full thickness of the gallbladder wall with variable extension into adjacent fat and connective tissue. This entity deserves distinct clinicopathological recognition, particularly because of a possible confusion with malignancy and the associated complications.

Adolescent↗

PubMed1989

Alkaptonuria.

A case of alkaptonuria with its various sequelae in the form of ochronosis, ochronotic arthropathy, spondylitis and prostatic calculi is reported. The case is of interest as it presented with hepatocellular failure and hepatitis B surface antigenaemia.

Alkaptonuria↗

PubMed1989

Skin involvement in leukemia.

Skin infiltration in leukaemia occurs rarely. We describe here four such cases of acute leukaemia. In two, the skin infiltration was evident at presentation; in the other two, it developed while on treatment. The lesions varied from maculopapular to tumorous stage. Complete remission could be achieved with chemotherapy, however, the long term prognosis was poor.

Adolescent↗

PubMed1989

Prevalence of haemoglobin D in Uttar Pradesh.

Haemolysates from 1098 unrelated individuals residing at Lucknow were investigated for haemoglobin variants by cellogel electrophoresis. Haemoglobin 'D' trait was found in 16 subjects (1.5%). The prevalence of Hb-D trait in Khatris was 3.1 per cent compared to 0.5 per cent in other Hindus. One case of Hb-D trait with thaiassaemia was also seen in a Muslim girl.

Adolescent↗

PubMed1989

Is high protein milk beneficial for SGA-terms?

A three months longitudinal followup of SGA term babies was done for their response to feeding of high protein milk (3.1 g/100 ml) and they were compared with their breast fed counterparts. The formula fed infants had no advantage over the breast fed when weight was compared. However, blood urea and serum creatinine levels were higher in the formula fed infants, than the breast fed ones. The serum valine concentrations, indicative of protein nutritional status, increased with increasing postnatal age in all the infants. Formula fed had higher serum valine than breast fed ones. Serum phenylalanine and serum tyrosine levels, which may hamper CNS development, were higher in the formula fed infants than the breast fed ones.

Follow-Up Studies↗

PubMed1988

Susceptibility of glucose-6-phosphate dehydrogenase deficient red cells to primaquine enantiomers and two putative metabolites--I. Effect on reduced glutathione, methemoglobin content and release of hemoglobin.

The effects of the primaquine (PQ) enantiomers, (+)PQ and (-)PQ, and two putative metabolites [5-hydroxyprimaquine (5HPQ) and 6-desmethyl-5-hydroxyprimaquine (6D5HPQ)] on methemoglobin (Met Hb) and glutathione content and release of hemoglobin into plasma from glucose-6-phosphate dehydrogenase (G-6-PD) deficient red cells were studied in vitro. The results show that a 1.5 mM concentration of (-)PQ produced a significantly greater increase in Met Hb content and decrease in reduced glutathione (GSH) level than did (+)PQ. However, the release of plasma hemoglobin was greater with (+)PQ than with (-)PQ. The hydroxy derivatives of primaquine, 5HPQ and 6D5HPQ, were significantly more active than PQ. Their individual effects differed; whereas 5HPQ produced significantly greater reduction in GSH compared to 6D5HPQ, the effect of 6D5HPQ on Met Hb content and release of plasma hemoglobin was greater than that of 5HPQ. The qualitative effects of these compounds on normal, heterozygous and hemizygous G-6-PD deficient red cells were similar, but quantitatively the effects were greatest on hemizygous G-6-PD deficient cells and intermediate on heterozygous cells.

Erythrocytes↗

PubMed1988

Tumor necrosis factor-mediated cytotoxicity involves ADP-ribosylation.

The mechanism of TNF-mediated cytotoxicity was studied in several cell lines, including L929 murine fibroblasts. TNF caused a time- and dose-dependent increase of ADP-ribosylation in L929 target cells parallel to cell death. During the course of TNF-mediated cytotoxicity in the presence of actinomycin D, an increase in ADP-ribosylation became apparent between 4 and 6 h after exposure to TNF. Intracellular NAD+ and ATP levels decreased parallel to but not preceding cell death. Two inhibitors of ADP-ribosylation, namely 3-aminobenzamide and nicotinamide, prevented TNF-mediated cytotoxicity. Another target, the human cervical carcinoma cell line ME-180, showed an increase in ADP-ribosylation when treated with TNF, and the cytotoxic action of TNF on this target cell was inhibited by these two inhibitors. In the absence of actinomycin D, treatment of L929 cells with TNF also increased ADP-ribosylation, and the cytotoxic action of TNF was inhibited by nicotinamide. These results indicate that ADP-ribosylation may be involved in the TNF-mediated cytotoxic reaction.

Adenosine Diphosphate Ribose↗

PubMed1988

Liposomes as membrane model for study of lipid peroxidation.

This article describes the properties, production and characterization of liposomes with special reference to their use as membrane model for the study of lipid peroxidation. It presents briefly the methods that can be used for the assay of liposomal lipid peroxidation and brings out the special advantages these liposomes provide in elucidating the mechanism of lipid peroxidation by different physical and chemical agents. Studies involving liposomal lipid peroxidation by different agents and the consequent changes in the structure and function of liposomal membrane have been reviewed briefly.

Animals↗

PubMed1988