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Biomedical subjects

J Gamble

Publications and source records attributed to J Gamble.

At least 91 records · Page 5Linked to original sources
PubMed1983

Influence of pH on capillary filtration coefficient of rat mesenteries perfused with solutions containing albumin.

A preparation of rat mesentery was vascularly isolated from the intestine and perfused with a physiological salt solution containing either Ficoll 70 or bovine serum albumin, to act as colloidal agents. The capillary filtration coefficient (Kf; units, ml. min-1 100 g-1 mmHg-1) was measured by following the weight change after graded increases in venous pressure. At pH values greater than 7.05, Kf, during perfusion with 3 and 4% bovine serum albumin solutions, was 0.219 +/- 0.023 (mean +/- S.E. of mean), ninety-eight observations in thirteen experiments, which was significantly less than the value of 0.507 +/- 0.038 which was obtained during perfusion with albumin solutions at pH less than 7.05, seventy-six observations in eleven experiments, (P less than 0.05). The value of Kf obtained during perfusion with 4% Ficoll solutions was 0.267 +/- 0.018, 119 observations in sixteen experiments, and remained uninfluenced by pH over the same range that had been used with the albumin solutions; however, perfusion of the tissues with Ficoll solutions at pH greater than 7.05, after perfusion with albumin solution pH less than 7.05, did cause the Ficoll-derived value of Kf to rise to 0.502 +/- 0.055, seventy-two observations in eleven experiments. It was concluded that the changes in Kf were not due to pH alone, but were mediated by albumin at acidic pH.

Animals↗
PubMed1981

The role of chromosome 15 in murine leukemogenesis. I. Contrasting behavior of the tumor vs. normal parent-derived chromosomes No. 15 in somatic hybrids of varying tumorigenicity.

G-banding analysis was carried out on a series of hybrids derived from the fusion of a chromosome 15-trisomic murine T-cell leukemia of AKR origin and normal diploid fibroblasts or lymphocytes of the CBT6T6 strain. Due to the 14;15 translocation involved in the generation of the T6 marker, the chromosomes No. 15 and 14 derived from the normal and the tumor parent can be distinguished cytogenetically. Highly tumorigenic, in vitro maintained hybrids, and high-tumorigenic segregants of originally low-tumorigenic in vitro hybrids, selected by in vivo passage, showed a similar cytogenetic pattern. It was characterized by the amplification of the tumor-derived chromosomes No. 15 from the expected 3 to 5.5 +/- 0.2 copies and a concomitant decrease of the normal derived T(14;15)6 from 2 copies to 0.9 +/- 0.2. All other autosomes except No. 14 showed only minor random variations, around the expected number of 4 copies. The tumor-derived chromosome 14 was amplified from the expected 2 to 3 copies. The low-tumorigenic hybrids showed the opposite pattern with a decrease in the number of the tumor-derived 15 chromosome from 3 to 2.6 +/- 0.1 and the maintenance of the two normal parent derived T(14;15)6 chromosomes. These findings suggest the existence of a qualitative difference between the 15 chromosomes derived from the tumor vs. the normal parent, due to mutation or proviral DNA insertion in the tumor-derived homologue. Amplification of the change locus and a decrease in the dosage of its normal counterpart appear to favor tumorigenicity.

Animals↗
PubMed1979

Influence of thymus genotype on acquisition of responsiveness in delayed-type hypersensitivity.

Antigen-pulsed macrophages (Mph) could sensitize syngeneic mice for delayed-type hypersensitivity (DTH) and also elicit sensitivity from mice sensitized to antigen in adjuvant provided these were syngeneic or semi-allogeneic to the strain providing the Mph. Sensitivity could not be elicited with antigen-pulsed allogeneic Mph. Antigen-pulsed Mph from low-responder (LR) strains could not sensitize LR mice nor F1 hybrids between responder (R) and LR strains. Normal F1 mice could be sensitized to respond to antigen presented on Mph or either parental type (i.e. P1 or P2): if, however, they were sensitized to antigen on P1 Mph, DTH transfer was restricted to naive P1 mice, not to P2 (restriction imposed by priming). F1 T cells derived from stem cells differentiating in a P1 thymus graft could be sensitized but could transfer sensitivity only to naive P1 mice, not to P2 (restriction imposed in thymus). When an antigen under Ir gene control was used, LR derived T cells differentiating in an (R X LR)F1 thymus could be sensitized but only if antigen was presented on (R X LR)F1 Mph not on LR Mph. Totally allogeneic chimaeras could be sensitized but only if given antigen in association with the appropriate Mph. These findings suggest that restriction of T cell activities can be imposed as a result of priming in some cases and as a result of differentiation within the thymus in others. LR strains appear to have a lesion at the level of antigen presentation by Mph; whether they also have a defect at the level of generation of T cell repertoire cannot be determined from the present investigations.

Animals↗
PubMed1979

Occupational safety and health implications of increased coal utilization.

An area of major concern in considering increased coal production and utilization is the health and safety of increased numbers of workers who mine, process, or utilize coal. Hazards related to mining activities in the past have been especially serious, resulting in many mine related accidental deaths, disabling injuries, and disability and death from chronic lung disease. Underground coal mines are clearly less safe than surface mines. Over one-third of currently employed underground miners experience chronic lung disease. Other stresses include noise and extremes of heat and cold. Newly emphasized technologies of the use of diesel powered mining equipment and the use of longwall mining techniques may be associated with serious health effects. Workers at coal-fired power plants are also potentially at risk of occupational diseases. Occupational safety and health aspects of coal mining are understood well enough today to justify implementing necessary and technically feasible and available control measures to minimize potential problems associated with increased coal production and use in the future. Increased emphasis on safety and health training for inexperienced coal miners expected to enter the work force is clearly needed. The recently enacted Federal Mine Safety and Health Act of 1977 will provide impetus for increased control over hazards in coal mining.

Anthracosilicosis↗
PubMed1978

T cell-dependent suppression of antibody production. I. Characteristics of suppressor T cells following tolerance induction.

Specific immunological tolerance was induced in adult CBA mice by a single injection of deaggregated human IgG (dHGG). Spleen cells taken 7 to 42 days later, produced consistent suppression of a DNP-HGG collaborative antibody response on adoptive transfer into heavily irradiated recipients. Noncentrifuged F(ab')2 fragments of HGG were as effective as dHGG in the production of suppressor cells. Suppression was antigen-specific since HGG-tolerant cells failed to abrogate either a DNP-keyhole limpet hemocyanin collaborative response or antibody production to the noncross-reactive antigen, horse erythrocytes. Pretreatment of the tolerant cell population with anti-Thy-1 serum and complement reversed the suppressive effect. However, purified tolerant T cells obtained by passage through nylon wool or anti-Ig columns were less effective than the original spleen cells in mediating suppression. Analysis of the cell types appearing in the column effluents indicated that the reduction in suppressive activity is best explained by retention of T cells rather than macrophages. Different T cell populations, however, were retained on the two types of columns. In the case of anti-Ig columns, these consisted of Ly-2,3+, Ia+ effector cells, whereas nylon wool columns caused depletion of Ly-1,2,3+ cells which are known to act as amplifiers of suppression. Suppression could not be explained in terms of delay in differentiation of antibody-forming cell precursors since the effect persisted for up to 15 days after transfer of tolerant cells. The demonstration of a reduction in serum anti-DNP and anti-HGG antibodies excluded the possibility of antibody production in sites other than the spleen. A role for anti-carrier antibody-antigen complexes in mediating the effector phase of suppression was rendered unlikely by the finding that the suppressive effect of tolerant cells persisted in the absence of detectable anti-HGG antibody production. Effector T cells mediating suppression in this system were shown to bear the phenotype Ia+, Ly-2,3+ as judged by the effect of pretreatment with appropriate antisera and complement. They were spleen-seeking, but were not detected in the thymus or recirculating lymphocyte pool. Adult thymectomy failed to cause a significant reduction in suppressive activity by tolerant spleen cells indicating that at least a major component of the immediate precursors is not of recent thymic origin.

Animals↗
PubMed1978

Major histocompatibility complex gene products on macrophages influence T cell activation.

Antigen-pulsed macrophages were used to sensitize or elicit sensitivity from mice of different strains to a variety of antigens. The results indicate that sensitization is directed, not to antigen as such, but to a complex structure on the macrophage surface determined partly by the antigen, and partly by a product coded by the major histocompatibility complex. Delayed type hypersensitivity could be provoked by antigen in responder (R) mice and in the F1 between responder and low responder (LR) strains, but not in LR mice unless pretreated by cyclophosphamide. Sensitivity could be transferred to naive LR-strain mice by lymph node cells taken 5 days after sensitization of cyclophosphamide-pretreated LR mice but not of F1 hybrids between LR and R strains. Sensitivity from these could be transferred only to naive F1 or R-strain mice. The results suggest that low responsiveness cannot be accounted for solely in terms of the operation of a cyclophosphamide-sensitive suppressor mechanism. It is postulated that antigen is less immunogenic when presented by LR-strain cells than by R-strain cells.

Animals↗
PubMed1977

Histocompatibility linked immune responsiveness and restrictions imposed on sensitized lymphocytes.

Delayed-type hypersensitivity (DTH) transfer to GAT was restricted by the I-A region of the major histocompatibility complex (MHC). Sensitized cells from F1 hybrid mice between responder and nonresponder strains transferred DTH to syngeneic F1 mice and to naive parental strain recipients of the responder but not of the nonresponder haplotypes. These results are interpreted to favor the postulate that the MHC-linked Ir genes exert their effects by coding for components which allow interactions between particular I region gene products and the region to form stable structures immunogenic for DTH T cells.

Alanine↗
PubMed1976

Role of major histocompatibility complex gene products in delayed-type hypersensitivity.

Sensitized thymus-derived (T) lymphocytes can transfer delayed-type hypersensitivity (DTH) to naive mice only if there is identity at the major histocompatibility complex (MHC). The MHC region responsible differs according to the antigen used for sensitization. For transfer of DTH to fowl gamma globulin identity at I-A is necessary; for dinitrofluorobenzene, however, identity at either K, D, or I region is sufficient. T cells of one genotype, sensitized in a chimeric environment, transferred DTH to both parental strains even though these were MHC incompatible. However T cells from F1 hybrid mice, sensitized not in the F1 but in one parental strain, transferred DTH only to that parental strain, not to the other, in contrast to F1 T cells sensitized in the F1 which could transfer DTH to both parental strains. Macrophages pulsed with antigen in vitro could be used to sensitize syngeneic or semi-allogeneic mice for the transfer of DTH. Transfer was, however, successful only in the strain syngeneic to that from which the macrophages were derived. Evidence is also presented that genetically low-responder mice can be made to exhibit DTH provided they are pretreated with cyclophosphamide two days before sensitization. When considered in toto these results strongly argue in favor of the notion that there are receptors on activated T cells which recognize antigenic determinants and MHC gene products. The implications of these findings are discussed in relation to the role of macrophages in antigen presentation and to the possible parallel evolution of MHC gene products and of T cell receptors for antigen.

Animals↗
PubMed1976

Effect of occupational and nonoccupational factors on the respiratory system of vinyl chloride and other workers.

There are suggestions in the literature that vinyl chloride (VC) acts as a lung irritant. Respiratory questionnaires and lung function tests were administered to 174 chemical (VC) workers, 81 polyvinyl chloride (PVC) workers, 72 former VC workers, and 136 rubber workers, and 68 maintenance workers with exposure to VC, PVC, and rubber. Except for small airways obstruction associated with rubber, increased respiratory symptoms and decreased pulmonary function were not associated with working in chemicals, plastics, or rubber. Some increases in baseline pulmonary function were associated with VC exposure. Acute reductions in pulmonary function were observed in smokers working in chemicals, plastics, and rubber. Heavier cigarette smokers over 40 years of age had the most adversely affected respiratory system. Work was not associated with chronic respiratory effects, but all exposure groups experienced some acute respiratory insult.

Adult↗