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Biomedical subjects

D W Johnson

Publications and source records attributed to D W Johnson.

At least 253 records · Page 14Linked to original sources
PubMed1980

Monocyte-induced potentiation of bovine fetal thymocyte mitogenic responses to concanavalin A.

Peripheral blood monocytes significantly potentiated the mitogenic response of bovine fetal thymocytes to Concanavalin A as measured by incorporation of [3H] thymidine into cellular DNA. Mononuclear cells obtained from either normal or Mycobacterium bovis sensitized cattle were cultured with or without purified protein derivative (PPD) for 24 hours at which time bovine fetal thymocytes and concanavalin A were added. After 3 days of culture, both activated or non-activated monocytes significantly potentiated Con A-induced blastogenic responses. of monocytes from thymocyte cultures completely abrogated thymocyte responses to Concanavalin A.

Animals↗
PubMed1980

Hearing in an ambulance paramedic population.

Ambulance cab noise levels during siren use, hearing levels of 56 ambulance paramedics, and hearing acuity changes of four ambulance paramedics during a 14-year period were examined to determine whether environmental noise levels are sufficient to produce hearing loss, to determine if hearing loss is indeed present in ambulance paramedics, and to determine if ambulance paramedics lose heaing acuity at rates faster than "normal" peers. Ambulance cab noise levels during siren use were intense (mean of 102.5 dBA in a common conditions), well above the Occupational Safety and Health Administration's suggested guidelines of 90 dBA. Hearing levels of paramedics were reduced from presbycusis expectations. In the lower and higher frequency ranges, the personnel showed hearing acuity approximately one standard deviation below the normal mean. This meant that mean hearing thresholds were depressed approximately 5 dB to 2 dB, depending on age and frequency. Ambulance paramedics over a 14-year term appeared to lose hearing acuity at a rate faster than "normal" peers. Implications from this study for hearing conservation are explored.

Adult↗
PubMed1980

Enumeration and characterization of bovine blood, spleen and lymph node cells containing immunoglobulins.

In this study, the average percentage of bovine spleen and lymph node cells with surface immunoglobulin (S-Ig) was found to be 19.62 and 23.18%, respectively. The average percentage of these cells with cytoplasmic immunoglobulin (C-Ig) was 14.46 and 17.21%. Only the percentage of cells with S-Ig showed a strong correlation between the spleen and the lymph node. Also, several methods of removing S-Ig from bovine peripheral blood mononuclear cells were investigated. It was found that the loss of passively bound S-Ig by warm washing was minimal, and that the anti-Ig-treated mononuclear blood cells would lose their caps after 24 h of incubation at 37 degrees C, but not after 45 min of incubation, although 95% of the cells with S-Ig were capped within 15 min.

Animals↗
PubMed1980

Producing positive interaction among Down syndrome and nonhandicapped teenagers through cooperative goal structuring.

Effects of cooperative, competitive, and individualistic goal structures compared on the dimensions of interpersonal interaction and attraction. Subjects were nonhandicapped and Down syndrome junior high school students who participated in eight weekly sessions of recreational bowling. Results indicated that significantly more positive interactions and evidence of greater interpersonal attraction took place between the nonhandicapped students and the Down syndrome students in the cooperative condition than in the competitive and individualistic conditions. .

Adolescent↗
PubMed1980

Involvement of calcium in mitogenic and immunoglobulin responses in bovine lymphocytes.

Removal of calcium from cultures of bovine splenic lymphoid cells with ethyleneglycol-bis-(2-amino ethylether)-N,N'-tetraacetic acid (EGTA) caused significant suppression of pokeweed mitogen-induced immunoglobulin (Ig) biosynthesis. It was found that removal of calcium for 48 hours of a 5-day culture significantly altered Ig biosynthesis. Re-addition of calcium after 48 hours did not restore Ig synthesis. The EGTA caused significant (P < 0.05) suppression of DNA synthesis when calcium was removed from concanavalin A- and purified protein derivative-stimulated peripheral blood lymphocyte cultures. Further, removal of calcium for 48 hours of 4-day cultures significantly altered the DNA synthesis in mitogen- and antigen-stimulated cultures.

Animals↗
PubMed1980

Gastrointestinal microbleeding: comparisons between benoxaprofen and other nonsteroidal antiinflammatory agents.

Unlike other nonsteroidal antiinflammatory agents, benoxaprofen has only minor antiprostaglandin synthetase activity. This property may explain the lack of gastric irritation seen in animal studies. To evaluate gastric irritation in man, benoxaprofen was compared with aspirin, naproxen, ibuprofen, sulindac, and indomethacin by measuring fecal blood loss with chromium-51 tagged red blood cells in randomized double-blind crossover and parallel studies. Benoxaprofen produced significantly less blood loss than aspirin, naproxen, or indomethacin, and less blood loss than ibuprofen or sulindac. Benoxaprofen also caused the fewest gastrointestinal complaints.

Anti-Inflammatory Agents↗
PubMed1980

Immunologic effects of experimental iodine toxicosis in young cattle.

A study was designed to evaluate effects of 4 dosage levels (0, 50, 250, or 1,250 mg) of daily iodine supplementation on cell-mediated and humoral immune mechanisms in 40 calves, 10 per group, for a 6-month period. Immune and inflammatory responses were measured by titers to brucella, leptospira, and infectious bovine rhinotracheitis virus vaccinations, by stimulation of lymphocyte mitoses with poke-weed, phytohemagglutinin (PHA), and conconavalin A mitogens, by intradermal PHA responses, by in vitro phagocytosis of Candida albicans by WBC, and by total WBC counts. Calves given 1,250 mg of iodine daily had significant (P = less than 0.05) decreases in persistence of antibody titers to brucella and leptospira organisms, in lymphocyte mitotic activity, in PHA injection induration, in phagocytosis by WBC, and in WBC counts. Calves fed iodine at 50 or 250 mg daily tended to have decreased leptospiral titers, lymphocyte mitoses, PHA injection induration, and in vitro phagocytosis by WBC compared with responses of controls. Seemingly, large amounts of dietary iodine interfere with titer maintenance to some antigens, with lymphocyte DNA synthesis, and with phagocytic activity of WBC.

Animals↗
PubMed1980

Evidence of cytocidal effects of Pasteurella haemolytica on bovine peripheral blood mononuclear leukocytes.

Pasteurella haemolytica had a pronounced cytocidal effect on bovine mononuclear leukocytes. Mononuclear leukocytes separated from venous blood on Ficoll-diatrizoate and incubated with either P haemolytica or Escherichia coli showed a significantly greater percentage cell death than did cells incubated with Staphylococcus epidermidis or controls. Neither heat-killed nor x-irradiated P haemolytica caused a significant percentage cell death. The cytotoxic potential of P haemolytica was dose related in that cell death among mononuclear leukocytes increased as the ratio of bacteria-to-cells increased. Enriched monocyte cultures showed a higher and less variable rate of cell death than either enriched lymphocyte or mixed leukocyte cultures.

Animals↗
PubMed1980

Studies on in vitro lymphocyte stimulation assay in cattle naturally infected with Brucella abortus and in cattle vaccinated with strain 19.

Cell-mediated immune responses of cattle in infected herds vaccinated with Brucella abortus, strain 19, and of nonexposed controls were studied by an in vitro lymphocyte stimulation test (LST). Brucella abortus soluble antigen was used as a specific stimulator of lymphocytes. Lymphocyte suspensions were prepared from peripheral blood of cattle by the Ficoll-diatrizoate technique. Cultures were labeled with [3H]thymidine and were assayed for [3H]thymidine incorporation into DNA by liquid scintillation spectrometry. Seroagglutination tests and cultures from Brucella were conducted simultaneously with LST. Brucella abortus soluble antigen induced significantly higher (P less than or equal to 0.005) lymphocyte stimulation responses in lymphocytes from cattle infected with B abortus than in lymphocytes from cattle vaccinated with strain 19 or from nonexposed controls. There was a significant P = agreement in results of LST and seroagglutination tests in infected cattle. Among seropositive-vaccinated cattle and controls, the LST was negative.

Animals↗
PubMed1980

Influence of time interval between administration of chloramphenicol and thiamylal on the sleeping time of mice.

The influence of the time interval between chloramphenicol and thiamylal administrations on the sleeping time of mice was studied. Two hundred 20- to 25-g mice were given (intraperitoneally) chloramphenicol or isotonic saline solution and then thiamylal at different time intervals between drugs. The duration of anesthesia was measured as the time between the loss and the return of the righting reflex. The results indicated that in mice given chloramphenicol simultaneously with thiamylal (0 time interval), the sleeping time was increased by a factor of about 10 as compared with the sleeping time in mice given thiamylal alone. As the time interval between administrations of thiamylal and chloramphenicol was increased (from 0.25 to 4 hours), the prolongation of sleeping time decreased correspondingly.

Animals↗
PubMed1979

Observations on diagnostic tests for paratuberculosis in a deer herd.

Paratuberculosis was diagnosed in a herd of 62 fallow deer (Dama dama) and 38 sika deer (Cervus nipon) maintained in an animal park in Ohio. A comparison was made of delayed-type hypersensitivity responses, results of in vitro lymphocyte immunostimulation tests, and isolation of Mycobacterium paratuberculosis on fecal culture in 19 deer.

Animals↗