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Biomedical subjects

M Bennett

Publications and source records attributed to M Bennett.

At least 397 records · Page 22Linked to original sources
PubMed1981

Homozygosity at the major histocompatibility complex is required for optimal immunogenicity of bone marrow cell allografts in irradiated rats.

Hemopoietic histocompatibility (Hh) Genes associated with the H-2 region control the antigenicity of hemopoietic cell grafts in the mouse. We have tested for similar genes in rats. Wistar Furth (WF, RTlu) or Lewis (LEW RTl1) bone marrow cell grafts did not proliferate in spleens of lethally irradiated (WFxLEW) F1 hybrid rats as assessed by measuring the incorporation of 5-iodo-2' deoxyuridine - 125I (IUdR) into recipient spleens 5 days after transplantation. In contrast, (WFxLEW) F1 hybrid marrow cells grew well in both WF and LEW parental strain hosts. (WFxLEW) F1 or (WFxLEW) F1 hybrid rats were backcrossed to WF parental strain rats to produce progeny, either homozygous, or heterozygous for the MHC. The RTl type of 46 individual backcross progeny was determined using a 5 day mixed-lymphocyte reaction (MLR). Correlation between RTl type and growth of marrow grafts of individual backcross rats were determined by using each rat as a bone marrow donor for irradiated LEW hosts. Marrow grafts from rats heterozygous for RTl were accepted in all 25 cases, whereas, grafts from 19 to 21 homozygous donors were rejected by the LEW hosts. Thus, homozygosity, for Hh determinants in or near the RTl region appears to be necessary for optimal immunogenicity of bone marrow allografts.

Animals↗
PubMed1981

Murine cytomegalovirus stimulates natural killer cell function but kills genetically resistant mice treated with radioactive strontium.

Treatment of C3H/St mice with 100 microCi of 89Sr weakened their genetic resistance to murine cytomegalovirus (MCMV) infection. The criteria utilized to detect increased susceptibility were: (i) survival of mice; (ii) numbers of MCMV-infected cells in the spleens and liver; and (iii) serum glutamic pyruvic transaminase levels. The natural killer (NK) cell activity of spleen cells from mice treated with 89Sr is very low. However, the NK activities of spleen cells of both normal and 89Sr-treated mice were greatly augmented 3 days after infection with MCMV. These NK cells lysed a variety of tumor cells and shared several features with conventional NK cells, but were not lysed by anti-Nk-1.2 serum (specific for NK cells) plus complement. Splenic adherent cells did not lyse tumor cells themselves but were necessary for the stimulation of NK cells by MCMV. The paradox of high NK cell function and poor survival in 89Sr-treated mice infected with MCMV was a surprise. We conclude that these augmented NK cells, of themselves, cannot account for the genetic resistance of C3H/St mice to infection with MCMV.

Age Factors↗
PubMed1981

Effect of herpes simplex virus type 2 and friend erythroleukemia virus infection of IgE antibody responses to Ascaris antigen in mice.

The IgE response to Ascaris antigen, as measured by passive cutaneous anaphylactic reactions, was suppressed in mice infected with either herpes simplex virus type 2 (HSV-2) or Friend leukemia virus (FV). FV was not suppressive unless infection preceded immunization whereas HSV-2 infection was immunosuppressive before or after immunization. However, the suppression by HSV-2 was relatively short-lived.

Animals↗
PubMed1981

Validity of impedance measurements and referral criteria in school hearing screening programmes.

The increasing use of impedance methods in screening programmes for auditory dysfunction requires that the techniques and validity of the referral criteria be continually monitored. This research report describes one such study carried out as part of the normal school hearing test procedure. Comparative measurements were made using conventional pure tone sweep audiometry and with the 'Tympanometer' (American Electromedics 85 AR). Results are based on 423 ears from 9-year old juniors and 298 ears from 5-year old infants. Agreement between the two methods was obtained with 81% of the juniors and 74% of the infants. The majority of the disagreement resulted from the high sensitivity of the impedance system in detecting middle-ear disorders which did not result in a hearing loss detectable by a 20-dB sweep. Significantly, the Tympanometer missed two infants with moderate sensorineural losses. These false negatives relate directly to the Tympanometer reflex system which proved to be unreliable. The need for care in the selection of instrumentation is stressed.

Acoustic Impedance Tests↗
PubMed1981

A comparison of the suppressor cells found in the spleens of 89SR-treated mice and in normal murine bone marrow.

Normal murine bone marrow cells and spleen cells of mice treated with 89Sr both have suppressive activity. These nonspecific suppressor cells inhibit the ability of normal spleen cells to undergo antibody responses in vitro. After being precultured for 24 hr, these cells will also suppress antibody responses in vivo and the responses of normal spleen cells to T and B cell mitogens in vitro. These cells have previously been shown not to be mature T or B lymphocytes or macrophages. Velocity sedimentation and cell-size analysis indicated that both suppressor cells are large (approximately 206 mu3). Mitomycin C treatment eliminated the ability of both suppressor cells to inhibit an in vitro antibody response. In contrast, this treatment did not reduce the ability of the cells to suppress a mitogenic response. Irradiation (1000 R) was also ineffective in eliminating the ability of either cell to suppress a mitogenic response We conclude that the 2 suppressor cells are closely related if not identical, and we speculate that these cells may function in vivo to suppress immune reactivity in areas of intense hematopoiesis.

Animals↗
PubMed1981

Mortality among workers in a die-casting and electroplating plant.

A proportional mortality and case-referent analysis of 238 deaths among hourly employees in an automobile hardware manufacturing plant was conducted. The major operations of the plant were zinc die casting and electroplating. Chemical exposure included die-casting emissions and mists from chrome and nickel plating. The chief proportional mortality finding was a significant excess of lung cancer among both white men and women. A case-referent analysis indicated a possible association between lung cancer and work in certain departments. The findings support the hypothesis of a work-related carcinogenic risk. Follow-up recommendations have been made.

Adult↗
PubMed1980

Immunosuppression by human plasma alpha 1-acid glycoprotein: importance of the carbohydrate moiety.

Human plasma alpha 1-acid glycoprotein (orosomucoid) and derivatives of this protein produced by sequential enzymatic cleavage of the glycosidic residue (sialic acid, galactose, N-acetylglucosamine, mannose) were tested for the ability suppress a number of immune functions of mouse spleen cells in vitro at physiological concentrations. alpha 1-Acid glycoprotein and especially the agalacto/asialo derivative suppressed (i) the mitogenic responses to concanavalin A, lipopolysaccharide, and alloantigens, (ii) antibody responses to sheep erythrocytes, and (iii) induction of cell-mediated lympholysis against allogeneic target cells. The native protein and its derivative did not inhibit the proliferation of EL-4 lymphoma cells and did not suppress the lysis of YAC-1 lymphoma cells by natural killer cells. The enhanced potency of the agalacto/asialo derivative indicates that the nature of the carbohydrate moiety exposed on the protein determines the effectiveness of the glycoprotein and its deglycosylated derivatives may function to regulate immune responses in various physiological and pathological conditions.

Antibody Formation↗
PubMed1980

Marrow-dependent cells depleted by 89Sr mediate genetic resistance to herpes simplex virus type 1 infection in mice.

Adult mice resistant to infection with 10(6) plaque-forming units of a virulent strain of herpes simplex virus type 1 were treated with 89Sr to abrogate marrow-dependent cell functions. Treated mice were found to be much more susceptible to the herpes simplex virus type 1 infection than untreated mice. The virus persisted in the visceral tissues of 89Sr-treated mice for 3 or more days postinfection but not in those of untreated mice. The virus also spread to the spinal cords of treated but not untreated mice. A marrow-dependent cell appeared to mediate resistance to herpes simplex virus type 1 by controlling the infection early after inoculation and not allowing the infection spread to the central nervous system.

Animals↗
PubMed1980

Problems in the psychotherapy of children with histories of incest.

Therapists must be cognizant of the meaning of the patients' presentation and the extreme need for therapeutic safety. The therapists must be keenly aware of the deprivation issues for these patients and not be seduced by the sexual "red herring." At the same time, the therapist must be careful that his own discomfort does not make him run away from the sexual material. Thus the therapist must strike a difficult balance between the two. The therapist must avoid allying with the child solely as a victim, an alliance which would hinder an understanding of the child's motivation and subsequent guilt, and thus foster further difficulties. The therapist must work through his own outrage that a child has been molested so that he may avoid blame seeking. By attending to these issues, the individual psychotherapist will pass the patients' "test" and take the first step in helping patients and their families in forming a therapeutic working alliance.

Adolescent↗
PubMed1980

Treatment of the elderly on a general hospital psychiatric short-stay unit.

Two out of seven general hospital psychiatric units and the local mental hospital in the Vancouver area set an arbitrary age limit of 65 or 70 on admissions. Administrative reasons given for this include the presumed likelihood of organicity and chronicity, implying difficulties in disposition, and problems in maintaining an active therapeutic milieu with patients of other ages. Data are presented on 40 patients who were over the age of 65 and accounted for 8% of all admissions during 1977 to a Psychiatric Short-Stay Unit in a downtown general hospital. It was found that over three-quarters of the admissions had a primary functional diagnosis, that the mean duration of stay was 5.73 days, that two-thirds of the patients were able to return to their former place of living on discharge and that over one-half of the patients located on follow-up, 18 to 24 months later, were still residing in the same situation. During hospitalization, almost one-half of the patients received no psychotropic prescription and almost one-third, no physical prescription. Some of the psychosocial factors in the treatment program are presented. It is concluded that this preliminary study suggests that the administrative apprehensions in relation to treatment of the elderly in general hospital psychiatric units and mental hospitals can be countered.

Aged↗