Effect of organo-tellurium compounds on the enzymatic alterations in rats

An attempt has been made to correlate early toxicity of organo-tellurium (Te) compounds with enzymic alterations in liver, kidney, brain and serum at 1 and 3 days following single i.p. injections of bis-(tetraphenyl phosphonium) tetracyanato-bis-p-methoxy p-phenyl tellurate(IV) (TTMT) and bis-(tetraheptyl ammonium) tetraiodocyclopentane tellurate(IV) (TACT). These compounds, at 2 and 1 mg Te/kg body weight as TTMT and TACT, respectively, produced cholinergic signs and caused death within 3 days. Administration at maximum tolerable doses of 0.5 mg and 0.1 mg Te/kg body weight as TTMT and TACT, respectively, resulted in significant reduction of acetylcholine esterase (AChE) and monoamine oxidase (MAO) in serum and brain and by a significant decrease in hepatic glutathione and in glutathione-S-transferase (GST) and alkaline phosphatase in liver and kidney.

Geometrical characterization of liquid core fibers by measurement of thermally induced mode cutoffs and interference

Transmitted and scattered intensity in liquid core fibers have been measured as a function of temperature and v values of cutoff points obtained which are in good agreement with weakly guiding mode theory. We also report observation of oscillations in the transmitted intensity which we interpret to be caused by interference between modes. We show that measurement of the period of these oscillations can be used to make high-precision nondestructive measurements of core radius and core ellipticity along the fiber length.

The effect of cadmium and manganese on the distribution of iron-59 in partially-hepatectomized rats

The distribution of iron-59 in blood at various time intervals was studied in sham and partially-hepatectomized rats after a single intravenous injection of 59Fe (III) citrate. A significant difference was observed in the rate of disappearance and reappearance of iron-59 in circulation. Administration of cadmium and manganese at a concentration of 0.5 and 2 mg/kg b.wt., respectively, did not cause any significant change in this pattern. A significant decrease in iron-59 incorporation in the liver of hepatectomized rat was produced by cadmium while manganese had no effect.

Haem and drug-metabolizing enzymes in regenerating rat liver

Various parameters of haem and drug metabolism were measured during the course of liver regeneration after two-thirds hepatectomy. Partial hepatectomy produced a significant depression in delta-ALA synthetase and delta-ALA dehydratase, and induction in haem oxygenase at an early stage of regeneration. The values returned to normal within 7-14 days. These changes were also accompanied by a marked decline in benzo(a)pyrene hydroxylase and aminopyrene demethylase. The level of glutathione and the activity of glutathione reductase also increased during the early stage of proliferation. The increased level of glutathione with concomitant decrease in drug-metabolizing enzymes and induction in haem oxygenase could be considered as a protective mechanism for the detoxication process, although a contribution from other biotransforming mechanisms cannot be excluded.

Deoxyribonucleic acid methylation in mycobacteria

Deoxyribonucleic acid modification in six strains of mycobacteria was investigated. The presence of 5-methylcytosine in the virulent strain Mycobacterium tuberculosis H37Rv and its absence in the avirulent strain M. tuberculosis H37Ra and other saprophytic, fast-growing mycobacteria appear to be the salient features. However, deoxyribonucleic acid from M. smegmatis SN2 lysogenized with the temperature phage I3 showed the presence of 5-methylcytosine. All of the strains had N6-methyladenine.

Isolation of a non-adhesive mutant of Vibrio cholerae and chromosomal localization of the gene controlling mannose-sensitive adherence

A mutant (CD11) of Vibrio cholerae was isolated after exposure of a wild-type pathogenic strain (KB207) to N-methyl-N'-nitro-N-nitrosoguanidine. Although the mutant was motile and chemotactic, it adhered poorly to rabbit intestinal mucosa. Pretreatment of vibrios with 10 mg D-mannose ml-1 and of intestinal mucosa with 100 mmol sodium metaperiodate inhibited adherence of KB207 but not of CD11. The gene (ams) controlling mannose-sensitive adherence was mapped on the bacterial chromosome closely linked to the pur locus.

Events in the pathogenesis of experimental cholera: role of bacterial adherence and multiplication

Pathogenic, and laboratory-derived non-adherent, non-motile, streptomycin-dependent and attenuated strains of Vibrio cholerae, were injected into the ileal loops of adult rabbits. The pattern of bacterial adherence and multiplication was studied. It was shown that all the strains multiplied to the same extent in the intestine; multiplication per se had no role in pathogenesis except when the infecting dose was low. Vibrio strains differed in their capacity to adhere to the intestine. A good correlation was found between adherence and pathogenesis. While adhesive strains were pathogenic, the poorly adhesive strains proved to be poor pathogens. There was no trace of toxin the ileal loops inoculated with poorly adhesive strains and very little in the diarrhoeal fluid produced by pathogenic strains. Adhesive strains adhered poorly to the intestine of immunised animals. It is suggested that adherence is concerned in the release of toxin and thus plays an important role in the pathogenesis of cholera.

Attenuated recombinant strains of Vibrio cholerae for oral immunization

Two attenuated strains of Vibrio cholerae, CD1 and CD3, have been isolated that have remained stable since 1976. These strains are motile, adhere to and multiply in rabbit intestine, and colonize the gut of infant mice for 6-7 days. Both strains are antigenic and provide protection to challenge in the mouse protection test and in the rabbit ileal loop model. Because of their ability to adhere to and colonize the gut, and since they are antigenic, strains CD1 and CD3 have the potentiality of oral vaccines.