Biomedical subjects

M Saxena

Publications and source records attributed to M Saxena.

At least 91 records · Page 5Linked to original sources

PubMed1990

Antimalarial activity of some 4-alkylamino 2/3 methoxy-4-aminodiphenyl sulphones.

From a series of thirty six 2,3, N-substituted 4,4'-diaminodiphenyl sulphones studied for their suppressive activity in mice against blood induced erythrocytic stage of Plasmodium berghei infection, six sulphones (1-6) showed 100% suppressive and curative activity at an intraperitoneal dose of 1 mg/kg x 4 days. These sulphones have been studied for their suppressive activity in still lower doses ranging from 1.0-0.25 mg/kg i.p. x 4 days and for their curative activity at 1 mg/kg i.p. x 4 days in comparison to DDS as standard drug. The maximum tolerated dose of these compounds and DDS has also been determined. These sulphones have better therapeutic efficacy for their suppressive and curative action than DDS.

Animals↗

PubMed1990

Phospholipase A production by isolates of Salmonella species.

The incidence of intra- and extra-cellular phospholipase-A production by Salmonella isolates from human, poultry and environmental material was investigated. Nearly 17 per cent (15/90) of the strains tested produced phospholipase A. Phospholipase production was encountered in S. typhi, S. paratyphi A, S. typhimurium, S. seftenberg, S. bareilly, S. weltevredeen, S. newport, S. adelaide, S. alachua and S. gallinarum. Maximum (10/15) phospholipase producers were isolated from the human material. Phospholipase positive human isolates exhibited a high incidence of simultaneous multiple drug resistance, enterotoxigenicity and cell surface hydrophobicity.

Animals↗

PubMed1989

Effects of aflatoxin on the immune system of the chick.

A decreased antibody response to injected sheep red blood cells and weight losses to the extent of 25-38% were observed in the bursa Fabricii and thymus in chicks fed an aflatoxin diet (10% w/w) for 3 weeks. The immune organs did not show any significant histopathological changes. The antibody titre decreased from day 6 of treatment onward until the 15th day, when the antibody titre had disappeared completely in the test chicks. The body weight gain was also less in test chicks (9.7-37.3%) given test feed or test feed along with Salmonella pullorum in water (10(8) cfu ml 1) in comparison to chicks given toxin-free diet and water after 3 weeks of feeding trials. The disappearing component in the test chicks' liver homogenate was found to be antigenic by immunoelectrophoretic studies.

Aflatoxins↗

PubMed1989

Heavy metal resistance in clinical isolates of Pseudomonas aeruginosa.

One hundred clinical isolates of Pseudomonas aeruginosa were checked for their sensitivity towards silver nitrate. Majority of the isolates were resistant at 20 mg/L and the resistance decreased with increasing concentration of silver nitrate, only 5% of the organisms showed resistance above 70 mg/L. These silver-resistant isolates were further checked for their resistance towards mercury and cadmium at 20 mg/L of concentration and the level of resistance was found to be 33 and 40%, respectively. A correlation between silver ion resistance and concurrent mercury and cadmium ion resistance was observed, suggesting a possible linkage between resistance towards various metal ions.

Anti-Bacterial Agents↗

PubMed1989

Factors affecting intra- and extracellular phospholipase A1 production by Salmonella newport.

The effect of various physico-chemical factors on production of intra- and extracellular phospholipase A1 by Salmonella newport was investigated. Maximum intracellular enzyme levels were observed when cells were grown in brain heart infusion broth, after 12 h of incubation at 37 degrees C. Highest level of extracellular phospholipase A1, however, was seen in synthetic medium (pH 7.0) after 24 h of incubation at 37 degrees C. Agitation during incubation had no effect on the intracellular enzyme synthesis but enhanced extracellular enzyme levels. Addition of surfactants to the growth media significantly decreased both intra- and extracellular phospholipase A1 production.

Aerobiosis↗

PubMed1989

Interaction of aflatoxin B1 metabolites with cellular macromolecules in neonatal rats receiving carcinogen through mother's milk.

A single dose of 2 microCi [3H] aflatoxin B1 (AFB1) containing 20 micrograms AFB1 was administered to the lactating rat. This resulted in the excretion of AFB1-metabolites in the milk, which were transferred and distributed in many tissues of the offspring consuming milk for 48 h. An equal distribution of radioactivity in liver and lung of suckling rats as well as in their sub-cellular fractions was observed. No AFB1 metabolite binding was apparent with tissue DNA. However, considerable binding of aflatoxin residues was observed with protein followed by RNA. Three metabolites have been detected in the milk sample derived from the stomach of the suckling rats on thin layer chromatogram with Rf values of 0.2, 0.4 and 0.8. Pretreatment of lactating rats with phenobarbitone (PB: 80 mg/kg/3 days) prior to the administration of [3H]AFB1 caused an overall decrease in the radioactivity in the neonatal tissues, particularly lung and intestine (P less than 0.05). The fluorescent bands with Rf values of 0.2 and 0.4 were not visualized in the milk sample from the PB group. Subsequently, the binding of AFB1 residues to cellular macromolecules of neonatal tissues was decreased. PB treatment further resulted in lowering the glucuronide/sulphate conjugates of AFB1 in the milk consumed by suckling rats; AFB1-glutathione (GSH) conjugates were slightly increased. These results point out the possibility that aflatoxin metabolites bind to the tissues of offspring fed by mothers consuming aflatoxin contaminated diets thus leading to chronic effects.

Aflatoxin B1↗

PubMed1989

Studies on 2,3,N,N'-substituted 4,4'-diaminodiphenylsulfones as potential antimalarial agents.

A series of new 4,4'-diaminodiphenylsulfones substituted at 2 and 3 position and also at primary amino group of the phenyl rings have been synthesized and evaluated for their antimalarial activity against Plasmodium berghei infection in mice. Some of these compounds were active and showed complete inhibition of parasitaemia which included 7a1-7a4, 7b3, 7b4 and 16a at 1 mg/kg i.p. for 4 days and 16a, at 0.3 mg/kg for 4 days. Some compounds tested for their synthetase inhibitory action in cell-free system isolated from P. berghei (7b1, 7b2 and 8b2) were found to be more active than diaminodiphenylsulphone. The difference in order of activity between these in vivo and in vitro tests may be due to differences in their pharmacokinetic properties.

Animals↗

PubMed1989

Incidence of klebocinogeny using two indicator systems.

The incidence of bacteriocinogeny among 117 clinical isolates of Klebsiella pneumoniae was examined using two systems of indicators-K. pneumoniae WC indicator and the Abbott-Shannon set of indicators. None of the isolate tested produced bacteriocin active on K. pneumoniae WC while 23 per cent positivity was observed with the Abbott-Shannon indicators. Most of the bacteriocin producers were urinary isolates (53.8%) followed by 15.3 and 30.7 per cent respectively of faecal and miscellaneous isolates. Our results indicate the advantages of using a set of indicators over a single indicator strain.

Bacteriocins↗

PubMed1988

Lack of influence of butylated hydroxytoluene on modification of lung microsome mediated aflatoxin B1-DNA binding: role of pulmonary glutathione S-transferase.

Phenolic antioxidants such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are known to inhibit tumor formation due to several chemical carcinogens including aflatoxin B1 (AFB1). Metabolic activation of AFB1 by lung microsomes and possible modification by dietary BHA was reported in an earlier communication (Allameh et al. (1988) Cancer Lett., 40, 49). Here we report the effect of dietary BHA at a high dose (0.75% for 15 days) and a low dose (0.06% for 180 days) on the activation and inactivation of AFB1 by subcellular preparations of lung. BHT at high dose alone induced hepatic cytosolic glutathione (GSH) S-transferases activity while the pulmonary enzyme was unaffected by BHT feeding. This observation was substantiated when the addition of lung cytosol from control and BHT-treated rats showed similar inhibition (50%) in the microsome mediated AFB1-DNA binding. Thus BHT appears to have little influence on the pulmonary metabolism of AFB1.

Aflatoxin B1↗

PubMed1988

Positive correlation exists between glutathione S-transferase activity and aflatoxin formation in Aspergillus flavus.

The presence of glutathione (GSH) S-transferase activity, using 1-chloro-2, 4-dinitrobenzene (CDNB) as a substrate, has been established in the cytosolic fraction of the toxigenic (aflatoxin producing) and nontoxigenic strains of Aspergillus flavus. Significant differences in the GSH S-transferase activity were observed between the toxigenic and non-toxigenic strains. A positive correlation has been demonstrated for the first time between aflatoxin formation and a biochemical parameter, namely GSH S-transferase activity. The evidence in support of A. flavus GSH S-transferase induction by endogenous aflatoxins is as follows: (i) the age-related production of aflatoxin follows the same pattern as the cytosolic GSH S-transferase activity profile; (ii) significantly higher enzyme activity was associated with mycelia of a toxigenic strain grown in medium supporting high aflatoxin production (sucrose-low-salts medium) while the enzyme activity was low in medium producing less aflatoxin (glucose-ammonium nitrate medium). The GSH S-transferase activity of the non-toxigenic strain was hardly affected by a change in the medium as it produces no aflatoxins; and (iii) the toxigenic strain demonstrated significantly higher apparent Vmax. with no change in Km as compared with the non-toxigenic strain. This indicates that the enzyme induction by endogenous aflatoxins is similar to the action of phenobarbitol and other inducing drugs (Kaplowitz et al., 1975).

Acetates↗

PubMed1988

Bacteriocin (klebocin) typing of clinical isolates of Klebsiella pneumoniae.

Three-hundred-forty-two clinical isolates of Klebsiella pneumoniae were subjected to bacteriocin (klebocin) typing using six standard klebocin-producer strains (153-158). The overall typability was 72.8 per cent. The predominant klebocin types found were 244 (14.3 per cent), 313 (13.7 per cent) and 113 (7.6 per cent). Klebocin types 314 and 111 each contributed 5.2 per cent to the total number of isolates. No significant correlation was observed between the source of isolation and the klebocin type.

Antibiosis↗

PubMed1988

Differential effects of butylated hydroxyanisole on metabolism of aflatoxin B1 in vitro by liver and lung microsomes.

Growing epidemiological evidence points out the carcinogenic hazard of inhaled aflatoxin B1 (AFB1) to the pulmonary system. Metabolism of AFB1 by lung microsomes and its binding to calf thymus DNA are reported for the first time in this paper. In addition, the ability of dietary butylated hydroxyanisole (BHA) to modulate AFB1 adduct formation with DNA was examined. Lung microsomes from BHA-treated rats unlike those from liver caused a 50% inhibition of AFB1-DNA binding. However, pulmonary cytosolic glutathione (GSH) S-transferase activity remained unaltered. The addition of BHA-treated lung cytosol failed to produce a greater inhibition of AFB1-DNA binding than control cytosol. Microsome mediated AFB1-DNA binding was markedly inhibited (30%) by the addition of GSH alone to the incubation system. Further addition of cytosol contributed much less (10%) to the inhibition of AFB1-DNA binding. These observations together with the induction of microsomal GSH S-transferase strongly implicate the role of microsomal GSH S-transferase in the modulation of AFB1-DNA binding.

Aflatoxin B1↗

PubMed1988

Survival of Staphylococcus epidermidis on the skin of patients of lepromatous leprosy.

The effect of hydration on Staphylococcus epidermidis, the predominant resident bacterial flora, was studied on skin affected by leprosy and known to have impaired sweating. Normal areas served as control. Significantly higher bacterial counts were observed in affected areas compared with normal-looking skin in 16/19 of the patients. Artificial application of Staph. epidermidis on leprosy-affected and unaffected areas, however, showed equivocal results, as in only 50% of the patients were higher counts obtained in affected compared with unaffected sites. The possible responsible factors for the present observation are discussed.

Bacterial Adhesion↗

PubMed1987