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Biomedical subjects

L Mitchell

Publications and source records attributed to L Mitchell.

At least 145 records · Page 8Linked to original sources
PubMed1982

Discordance between the anti-Xa activity and the antithrombotic activity in an ultra-low molecular weight heparin fraction.

The relationship between the in vivo antithrombotic effect of heparin and ex vivo anti-Xa activity has been investigated using an animal thrombosis model. Three low molecular weight heparins were compared with the standard heparin from which they were fractionated. All four heparins showed a dose-dependent antithrombotic effect enabling the relative antithrombotic and anti-Xa activities to be compared over a dosage range. A correlation between ex vivo anti-Xa heparin levels and antithrombotic effect was demonstrated for the standard (MW 16,000), intermediate (MW 7,600) and low (MW 4,600) molecular weight heparins but not for the ultra-low molecular weight (MW 3,000) fraction. The lack of relationship between anti-Xa activity and inhibition of thrombosis for the very low molecular weight fraction indicates that a very high anti-Xa activity (measured in vitro or ex vivo) is not always predictive of in vivo antithrombotic efficacy. These findings suggest that other properties of low molecular weight heparins contribute to their antithrombotic effectiveness.

Animals↗
PubMed1982

Poxvirus infection in a colony of common marmosets (Callithrix jacchus).

An epizootic poxvirus infection occurred in a colony of 80 common marmosets (Callithrix jacchus) recently introduced to a laboratory facility. Over an 18-week period, 29 of the monkeys exhibited skin lesions that persisted for 4-6 weeks. Although eight marmosets died during the outbreak, their deaths were not attributed directly to the poxvirus infection. The skin lesions developed over the entire body surface including the soles and palms. Initially characterized as erythematous papules, they quickly changed to elevated coalescing lesions with extensive scab formation. Histopathologically, the lesions revealed moderate to marked acanthosis, and they progressed to full-thickness epidermal necrosis and ulceration. Intracytoplasmic inclusion bodies were observed occasionally within degenerate keratinocytes. These inclusions most probably constituted the intracytoplasmic aggregates of viral particles observed ultrastructurally and confirmed as members of the poxvirus group by negative staining of direct skin scrapings.

Animals↗
PubMed1979

Host defense in Cryptococcosis. III. In vivo alteration of immunity.

The present studies utilize an inbred mouse model to evaluate the adoptive transfer of spleen cells to augment immunity against Cryptococcus neoformans. Protection against cryptococcosis was transferred using spleen cells obtained from mice surviving cryptococcosis. These spleen cell donors had no detectable anticryptococcal antibody. Also, treatment with antimouse-thymocyte globulin ablated dermal hypersensitivity reactions of immunized mice, and shortened survival in both immunized and unimmunized mice. These in vivo studies further support a major role for cell-mediated immunity in host defense against experimental cryptococcosis.

Animals↗
PubMed1979

Host defense in cryptococcosis. III. Protection of nude mice by thymus transplantation.

Congenitally athymic (nude) BALB/c mice, which are homozygous for the nu gene, are extremely susceptible to challenge with Cryptococcus neoformans. Groups of nude mice received transplants of thymus tissue obtained from either heterozygous (nu/+) mice or normal BALB/c mice not carrying the nu gene. Survival and delayed-type hypersensitivity were measured after challenge with cryptococci. Mice that received thymus tissue from a heterozygous (nu/+) or normal BALB/c mouse donor had markedly prolonged survival after challenge. In addition, mice that received thymus tissue from normal BALB/c mice developed delayed-type hypersensitivity to cryptococcal antigens following challenge. These studies indicate that transplantation of thymus tissue effectively increases host immune resistance against C. neoformans.

Animals↗
PubMed1978

Treatment of experimental murine cryptococcosis: a comparison of miconazole and amphotericin B.

Miconazole was compared with amphotericin B in the treatment of murine cryptococcosis. Both subcutaneous and intraperitoneal administration of miconazole produced serum levels higher than the minimum inhibitory concentration for the challenge strain. However, maximal tolerable doses of miconazole gave no increase in survival. When combined with amphotericin B, miconazole demonstrated neither additive nor antagonistic effects on survival. Spleen and brain counts of cryptococci were not lowered by miconazole; also, miconazole did not alter the effect of amphotericin B on reducing tissue counts. In vitro studies confirmed that the strain of Cryptococcus neoformans was quite susceptible to both miconazole and amphotericin B. However, miconazole had a delayed onset of antifungal activity. This was apparent even at miconazole levels 20 times greater than the minimum inhibitory concentration. Also, the antifungal activity of miconazole was markedly inhibited by serum. Delayed antifungal activity and serum inhibition may limit the in vivo effectiveness of miconazole in murine cryptococcosis.

Amphotericin B↗
PubMed1978

Cyclophosphamide effects on murine cryptococcosis.

BALB/c mice were given cyclophosphamide and challenged with Cryptococcus neoformans. Delayed-type hypersensitivity was transiently depressed, and survival was either unaffected or shortened by cyclophosphamide.

Animals↗
PubMed1978

Attitudes of caretakers toward the sexual behavior of mentally retarded persons.

A multidimensional questionnaire was administered to staff members at three residential facilities for retarded persons to determine their attitudes toward the actual and potential sexual behavior of retarded persons. The questionnaire covered the areas of masturbation and heterosexual and homosexual behavior. Dimensions were scaled to reflect progressively more intimate behavior so that acceptability of each response along the dimensions could be assessed. A mean of 31.2 percent of those questioned felt that no sexual behavior, not even simple physical contact, was acceptable for retarded persons. This indicates that sex-education programs for retarded persons may be met with resistance by a substantial percentage of staff. Among those staff members who found it acceptable for retarded people to engage in sexual behavior, peak acceptability occurred for heterosexual behavior. Sexual behavior in public, especially public masturbation, was considered a significant problem. More specific effects were identified, and the implications of these results for educational programs and the development of intervention procedures were discussed.

Adolescent↗