Biomedical subjects

A Horowitz

Publications and source records attributed to A Horowitz.

At least 109 records · Page 6Linked to original sources

PubMed1977

Response of microorganisms to an accidental gasoline spillage in an arctic freshwater ecosystem.

The response of microorganisms to an accidental spillage of 55,000 gallons of leaded gasoline into an Arctic freshwater lake was studied. Shifts in microbial populations were detected after the spillage, reflecting the migration pattern of the gasoline, enrichment for hydrocarbon utilizers, and selection for leaded-gasoline-tolerant microorganisms. Ratios of gasoline-tolerant/utilizing heterotrophs to "total" heterotrophs were found to be a sensitive indicator of the degree of hydrocarbon contamination. Respiration rates were elevated in the highly contaminated area, but did not reflect differences between moderately and lightly contaminated areas. Hydrocarbon biodegradation potential experiments showed that indigenous microorganisms could extensively convert hydrocarbons to CO(2). In situ measurement of gasoline degradation showed that, if untreated, sediment samples retained significant amounts of gasoline hydrocarbons including "volatile components" at the time the lake froze for the winter. Nutrient addition and bacterial inoculation resulted in enhanced biodegradative losses, significantly reducing the amount of residual hydrocarbons. Enhanced biodegradation, however, resulted in the appearance of compounds not detected in the gasoline. Since the contaminated lake serves as a drinking water supply, treatment to enhance microbial removal of much of the remaining gasoline still may be advisable.

Alaska↗

PubMed1977

Nocardia infections in congenitally athymic (nude) mice and in other inbred mouse strains.

The mortality rate and histopathological features of Nocardia asteroides and Nocardia brasiliensis infections in congenitally athymic (nude) mice of ICR and C3H/eB origins were quite different from what we found for Swiss white mice and other inbred mouse strains (namely, C57/BL/6J, New Zealand Black, BALB/c, CBA/LAC, and C3H/eB). The immunocompetent littermates of the congenitally athymic mice occupied an intermediate position between their athymic siblings and Swiss white mice in terms of their responses to both these organisms. Macrophage ingestion and destruction of N. brasiliensis, as demonstrated by electron microscopy, was found to occur. The T-lymphocyte appears to be an essential component in normal mouse resistance to infection by both N. asteroides and N. brasiliensis.

Animals↗

PubMed1977

Amyloidosis developing in experimental nocardia infections.

Swiss white and C57/BL/6J mice inoculated repeatedly with either Nocardia asteroides or Nocardia brasiliensis organisms developed amyloidosis over a 7-month period. Amyloidosis also developed in these mice within 6 weeks following a single large inoculum of either organism, but not in other in-bred mouse strains, suggesting a genetic influence in the pathogenesis of this form of secondary amyloidosis.

Amyloidosis↗

PubMed1976

Lymphocytic infiltration in endometrial adenocarcinoma. Correlation with histologic differentiation, clinical staging and prognosis.

Lymphocytic infiltration in endometrial adenocarcinoma was evaluated in curettings from 50 patients and correlated with histologic differentiation, clinical staging and prognosis. In spite of the absence of any significant correlation between lymphocytic infiltration and the various parameters investigated, the presence of a marked infiltrate in 46% of the cases suggests that in endometrial adenocarcinoma, as in other neoplasms, a cell-mediated immune response does indeed exist, but warrants further investigation by more refined methods.

Adenocarcinoma↗

PubMed1975

Sequential growth of bacteria on crude oil.

By modification of the enrichment culture procedure three bacterial strains capable of degrading crude oil in sea water were isolated in pure culture, UP-2, UP-3, and UP-4. Strain UP-2 appears to be highly specialized for growth on crude oil in sea water since it showed strong preference for oil or oil degradation products as substrates for growth, converted 66% of the oil into a form no longer extractable by organic solvents, quantitatively degraded the paraffinic fraction (gas chromatographic analysis), emulsified the oil during exponential growth, and produced 1.6 x 10-8 cells per mg of oil. After exhaustive growth of UP-2 on crude oil the residual oil supported the growth of UP-3 and UP-4, but not a previously isolated oil-degrading bacterium, RAG-1. Strains UP-2, UP-3, and UP-4 grew on RAG-1-degraded oil (specifically depleted of n-alkanes). The growth of UP-3 and UP-4 on UP-2 and RAG-1-degraded oil resulted in the production of new paraffinic compounds as revealed by gas chromatography. When the four strains were grown either together in a mixed culture or sequentially, there was over 75% oil conversion. By plating on selective media, growth of the individual strains was measured kinetically in the reconstituted mixed culture, revealing competition for common growth substances (UP-2 and RAG-1), emhanced die-off (UP-2), and stabilization (UP-4) during the stationary phase.

Alkanes↗

PubMed1975

Prosthetic valve endocarditis due to Mycobacterium chelonei.

Postoperative prosthetic valve endocarditis due to Mycobacterium chelonei occurred in a man after replacement of the aortic valve. The organism was isolated from blood cultures and from vegetations taken postmortem from the edge of the inserted valve. This is believed to be the first documented report of a mycobacterial endocarditis.

Autopsy↗

PubMed1975

A study of articular surfaces and synovial fossae of the pectoral limb of swine.

Articular surfaces of the pectoral limb were studied in 50 swine and are described in detail. Synovial fossae were not present at birth but were found commonly on the articular surface of the scapula, distal humerus, proximal radius, distal radius and distal surfaces of the intermediate carpal bone after four to five months of age. When present, they were bilaterally symmetrical and were located at the depth of a concavity of the articular surface. Microscopically, synovial fossae appeared as an invagination of articular cartilage extending into subchondral bone. Evidence of endochondral bone formation was less apparent at the depth of synovial fossae than in areas of weight bearing cartilage.

Animals↗

PubMed1974

Thymineless death in Bacillus subtilis: correlation between cell lysis and deoxyribonucleic acid breakdown.

Bacillus subtilis carrying an inducible defective phage is several times more sensitive to thymineless death than a mutagenized derivative that behaves as a nonlysogen. When the integrity of the deoxyribonucleic acid (DNA) of both strains was examined during thymine starvation by transformation experiments, sedimentation studies, and measurements of acid-soluble DNA degradation products, it was shown that extensive DNA breakdown occurred only in the lysogenic strain. During thymine starvation of this strain, there is a progressive proclivity to lysis, followed by leakage of DNA and DNA degradation products. Such leakage was not observed in the nonlysogen. A correlation between proclivity to lysis and extensive DNA degradation is indicated.

Adenine↗

PubMed1974