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Biomedical subjects

M M Stevenson

Publications and source records attributed to M M Stevenson.

At least 91 records · Page 5Linked to original sources
PubMed1982

Murine malaria: genetic control of resistance to Plasmodium chabaudi.

Strain variation in the level of resistance to malaria was investigated in inbred strains of mice after infection with Plasmodium chabaudi. When infected intraperitoneally with 10(6) P. chabaudi-parasitized erythrocytes, mice of 11 inbred strains could be separated into two groups by using survival time as the criterion; C57BL/6J, C57L/J, DBA/2J, CBA/J, and B10.A/SgSn mice were found to be resistant to P. chabaudi, whereas A/J, DBA/1J, BALB/c, C3H/HeJ, AKR/J, and SJL/J mice were susceptible. An examination of F1 hybrids revealed that resistance was dominant over susceptibility. A segregation analysis of backcross and F2 progeny derived from susceptible A/J and resistant B10.A/SgSn parental mice suggested that host resistance in this strain combination was genetically controlled by a single, dominant, non-H-2-linked gene. Inheritance of resistance was autosomal, but expression of the trait was influenced by the sex of the host, female mice being more resistant than male mice. Phenotypic expression of the resistance gene was apparent within 6 days of infection as a significant difference between resistant and susceptible mice in the level of parasitemia. A preliminary analysis of the mechanism of resistance showed that compared with susceptible A/J mice, resistant B10.A/SgSn hosts had an augmented erythropoietic response during the course of malaria, as well as phenylhydrazine-induced anemia. These results suggest that the ability to replace destroyed erythrocytes quickly and efficiently may determine host survival after infection with P. chabaudi.

Anemia↗
PubMed1982

Macrophages in resistance to rickettsial infections: genetic analysis of susceptibility to lethal effects of Rickettsia akari infection and development of activated, cytotoxic macrophages in A and B10.a mice.

Susceptibility to lethal effects of Rickettsia akari varies among mouse strains. Although most strains are resistant, A/J mice are extremely sensitive (10,000-fold difference in LD50 between resistant and sensitive strains). In contrast to most strains of mice, A/J mice also fail to develop activated, tumoricidal macrophages after any of several in vivo or in vitro treatments. Are susceptibility to R. akari and inability to develop activated, cytotoxic macrophages in the A/J strain causally related traits? Genetic analysis of macrophage tumoricidal activity in responsive B10.A and nonresponsive A mice suggested this trait was controlled by a single, autosomal, dominant gene. Among (F1 X A) backcross mice, the traits for defective macrophage cytotoxicity and abnormal accumulation of macrophages during inflammation (a response controlled by a single, autosomal, dominant gene) segregated independently. Genetic analysis of resistance to R. akari in sensitive A and resistant B10.A mice suggested this trait was also controlled by a single, autosomal, dominant gene. Among (F1 X A) backcross mice, however, traits for defective macrophage cytotoxicity and R. akari resistance segregated independently. Thus, development of activated tumoricidal macrophages, accumulation of macrophages at sites of inflammation, and resistance to the lethal effects of R. akari in A and B10.A mice were each controlled by single, autosomal, dominant, non-H-2-linked genes. However, genes for control of macrophage activation for tumoricidal activity and for resistance to lethal effects of R. akari infection are distinct.

Animals↗
PubMed1981

Genetic linkage of resistance to Listeria monocytogenes with macrophage inflammatory responses.

The mobilization of adequate numbers of mononuclear phagocytes to inflammatory foci was measured in Listeria-resistant and Listeria-sensitive mice. Resistant strains, such as B10.A, were found to have a 2- to 3-fold greater accumulation of peritoneal macrophages after i.p. treatment with a variety of nonspecific inflammatory stimuli in comparison to sensitive strains, such s A/J. In addition to low macrophage inflammatory responses, A/J mice had fewer resident peritoneal macrophages. Moreover, measurement of chemotaxis in vitro of equal numbers of thioglycollate-induced macrophages showed cells from A/J mice to be less responsive to complement-derived chemotactic factors. Thus, the mononuclear phagocyte systems of resistant B10.A and sensitive A/J mice were quantitatively and qualitatively different. A survey of inbred mouse strains revealed that these differences were not peculiar to A strain mice and that, in general, the level of the in vivo macrophage inflammatory response correlated with the level of resistance to Listeria in a given strain. Like resistance to Listeria, the macrophage inflammatory response was found to be genetically controlled by an autosomal, non-H-2-linked gene(s) expressed as incompletely dominant. Backcross analysis showed genetic linkage of the macrophage inflammatory response with resistance to Listeria. Thus, the results of this study provide formal evidence that the cellular basis of the genetically determined, enhanced resistance to Listeria is an augmented pool size of mononuclear phagocytes, and the prompt mobilization of these cells to foci of infection.

Animals↗
PubMed1980

Pneumatic calf compression, fibrinolysis, and the prevention of deep venous thrombosis.

In a previous pilot study that did not reach statistical significance, intermittent single-leg pneumatic compression appeared effective in reducing the incidence of calf vein thrombosis not only in the pumped calf but also in the unpumped leg in 37 patients, using the 125I-fibrinogen (Abbott Laboratories) technique. The present study was undertaken to investigate mechanical induction of local and systemic fibrinolysis. The euglobulin lysis time in the arm venous effluent was determined in five volunteers before and after unilateral arm compression for 1/2 hour. Shortening averaged 19% (not significant). The experiment was repeated using bilateral calf-length boots with femoral vein sampling. Euglobulin lysis decreased 22% (P < 0.001). To uncover possible systemic effects, the protocol was altered using calf boots with sampling from the arm. The euglobulin lysis diminished 6% in 57 volunteers (P < 0.001). In 27 others the effects of thigh-length and calf-length boots were compared. In half, pumping with a short boot was undertaken first, and in the remainder, the long boot was applied initially. One-half hour of pumping was followed by 1/2 hour of rest. Immediately afterward the second period of pumping took place and continued for 1/2 hour. A total of four arm vein samples were obtained, one before and after each pumping period. Although, in retrospect, the 1/2-hour rest period was inadequate to permit the subjects to return to basal conditions, statistically significant decreases in euglobin lysis time (P = 0.05) occurred with the long boots. This study shows intermittent calf compression increases fibrinolytic potential locally and this effect can be demonstrated systemically. The greater the volume of tissue compressed, the greater the response. The efficacy of intermittent venous compression in reducing the incidence of deep venous thrombosis may be due, in part, to localized induction of fibrinolysis.

Adult↗
PubMed1977

Characterization of macrophage chemotaxins in tumor cell cultures and comparison with lymphocyte-derived chemotactic factors.

Culture fluids from five murine sarcomas were chemotactic for syngeneic peritoneal macrophages in vitro. Peritoneal macrophages from mice infected with Mycobacterium bovis, strain Bacillus Calmette-Guérin, were more responsive to the chemotactic factor in tumor cultures than were normal macrophages. Peritoneal granulocytes, however, did not significantly respond to this factor. The level of chemotactic activity in tumor cultures paralleled cell growth for all five tumors; maximal levels occurred during log growth. Culture medium alone or fluids from proliferating spleen cell cultures stimulated with mitogens did not have detectable chemotactic activity. Chromatography of the tumor culture fluids resulted in a single peak of chemotactic activity in the 15,000-molecular weight range on Sephadex G-100 and at about 7.5 mmho/cm specific conductance on diethylaminoethyl cellulose. By both biological and physicochemical characteristics, the chemotactic activity in tumor culture fluids was different from mouse lymphocyte-derived chemotactic factor.

Animals↗
PubMed1976

Depressed chemotactic responses in vitro of peritoneal macrophages from tumor-bearing mice.

The in vitro chemotactic responses of peritoneal macrophages from mice bearing transplantable syngeneic 3-methylcholanthrene-induced tumors in their footpads were depressed to about 50% of normal levels. This chemotactic defect to both lymphocyte- and complement-derived stimuli was evident before the appearance of palpable tumor (within 1 week of tumor injection) and persisted until the death of the animal by 6-8 weeks. Chemotactic depression was not observed with macrophages from mice treated with tissue culture medium, fetal calf serum, incomplete Freund's adjuvant, or syngeneic spleen cells.

Animals↗