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Biomedical subjects

D V Vadehra

Publications and source records attributed to D V Vadehra.

At least 37 records · Page 2Linked to original sources
PubMed1986

Effect of fatty acids on aflatoxin production by Aspergillus parasiticus.

The effect of saturated and unsaturated fatty acids on aflatoxin production was studied in a synthetic medium. The aflatoxin production decreased (10-75%) in the presence of lauric acid and palmitic acid but the addition of behenic and sebacic acid stimulated aflatoxin production by 125-541%. Linolenic and linoleic acids effected aflatoxin production and mycelium growth. An 34-fold increase in aflatoxin production was observed with 50 mM linoleic acid. An inverse relationship was observed between aflatoxin production and mycelium mass, irrespective of the nature of the fatty acid.

Aflatoxins↗
PubMed1986

Effect of metal ions on aflatoxin production by Aspergillus parasiticus.

The effect of iron, copper, cobalt, cadmium, zinc, molybdenum, magnesium and manganese salts was studied on aflatoxin production in relation to mycelial mass. Iron, copper and cadmium salts decreased the aflatoxin production to different levels but a mixed trend was observed depending on salt concentration, with molybdenum, magnesium and manganese. Cobalt and zinc salts stimulated aflatoxin production at all concentrations studied. The maximum increase in aflatoxin production, 655% and 519% was observed in the presence of zinc sulfate and sodium molybdate, respectively. A negative correlation was observed between aflatoxin production and vegetative growth of fungus.

Aflatoxins↗
PubMed1986

Purification and characterization of a bacteriocin from Klebsiella pneumoniae 158.

Klebocin, a bacteriocin produced by Klebsiella pneumoniae 158, was purified to homogeneity by ammonium sulphate fractionation and sequential DEAE-Sephacel and Sephadex G-150 column chromatography. The purified preparation had an Mr of approximately 40 000 on SDS-PAGE. Chemical analysis of the purified preparation showed it to be a protein, and it was sensitive to digestion by various proteolytic enzymes.

Bacteriocins↗
PubMed1986

Drug resistance patterns and susceptibility to aflatoxin B1 of strains of Escherichia coli and Staphylococcus aureus.

The antibacterial properties of aflatoxin B1 have been evaluated against antibiotic-resistant clinical isolates of Escherichia coli and Staphylococcus aureus. The inhibition of growth ranged from 11.5 to 60.0% and 4.5 to 18.5% in the strains of S. aureus and E. coli, depending on the extent of drug resistance. Aflatoxin-B1 binding varied with toxin concentration, the presence of surfactants (Tween-80 or EDTA) as well as with the antibiotic-resistance pattern; binding was maximal in antibiotic-sensitive strains and least in the most resistant strains. Binding of aflatoxin B1, correlated with growth inhibition. Aflatoxin B1 also caused leakage of cell contents and decrease in inulin uptake, effects which were also concentration dependent.

Aflatoxin B1↗
PubMed1986

Mechanism of resistance to silver ions in Klebsiella pneumoniae.

The uptake of silver by an experimentally derived silver-resistant Klebsiella pneumoniae strain was three to four times lower than the uptake by a susceptible strain. Spheroplasts of the two strains showed no difference in uptake. AgNO3 at a concentration of 40 micrograms/ml decreased the succinate dehydrogenase activity in susceptible and resistant strains by 100 and 18%, respectively. More than one resistance mechanism may be involved.

Drug Resistance, Microbial↗
PubMed1985

Mechanism of action of aflatoxin B1 in Bacillus megaterium.

Bacillus megaterium cells from various growth phases were equally susceptible to the lethal effects of aflatoxin B1. Known surfactants (EDTA and Tween-80) accentuated the effects of aflatoxin B1. Viability and inulin uptake in aflatoxin B1-exposed cells decreased considerably. The effect was concentration dependent. A straight-line relationship observed in the death curve indicated a single target for aflatoxin B1 action in B. megaterium. Leakage of intracellular constituents in B. megaterium was also concentration dependent, and this can be related to the extent of cell membrane damage.

Aflatoxin B1↗
PubMed1983

Survival of Salmonella typhimurium and Staphylococcus aureus in eggs cooked by different methods.

Shell eggs inoculated with Salmonella typhimurium and Staphylococcus aureus were cooked by recommended procedures for boiling, poaching, and frying. Except for poaching, the recommended procedures were inadequate in destroying the inoculum placed in the yolk. Boiling for 7 min was necessary for complete destruction of S. typhimurium and it took 12 min of boiling to destroy Staph. aureus. Cooking time-temperature relationship for complete kill depended on the cooking method with fried eggs. Four minutes and 70 C were needed for covered eggs, 3 min on each side at 64 C for turned over eggs, while cooking for 7.5 min at 64 C for sunnyside eggs was not sufficient for destruction of both of the test organisms. None of the test organisms could be recovered from omelets baked by the recommended procedure (86 C for 25 min). Scrambling for 1 min at 74 C was required for the complete destruction of S. typhimurium and 2 min at 78 C for Staph. aureus.

Eggs↗
PubMed1982

Proteins of the outer layer of the vitelline membrane of hen's eggs.

A study has been made of the proteins in the vitelline membrane of hen's eggs before and after mechanical separation into the inner and outer layers. The membranes were dissolved in detergent (sodium dodecyl sulphate) and chromatographic fractions were examined by gel electrophoresis. The separated inner and outer layers were compared by gel electrophoresis. The outer layer contained (i) enzymically active lysozyme (EC 3.2.1.17) (about 60% dry weight), (ii) an insoluble ovomucin complex and (iii) a new protein, VMOI (vitelline membrane outer I). These account for most of the protein. In addition, some minor constituents were detected by gel electrophoresis but were not isolated. Except for ovomucin, the constituents of the outer layer could be dissolved from the membrane at high ionic strength (greater than 0.5 M sodium chloride), resulting in a loss of its structure. On lowering the ionic strength the soluble proteins recombined with the membrane, partially regenerating the original structure. Ovomucin appears to form the skeleton of the outer layer, but the salt-soluble proteins, especially lysozyme, are responsible for its integrity. The function of the newly-recognized protein (VMOI) is not known. Its molecular weight is 17,500 according to gel electrophoresis in detergent and it contains no methionine. The inner layer consists largely of the proteins GPI, GPII and GPIII isolated by Kido et al. (Kido, S., Janado, M. and Nunoura, H. (1975) J. Biochem. 78, 261-268) from the whole membrane.

Animals↗