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Biomedical subjects

D W Johnson

Publications and source records attributed to D W Johnson.

At least 307 records · Page 17Linked to original sources
PubMed1978

Specific lymphocyte stimulation in cattle naturally infected with strains of Brucella abortus and cattle vaccinated with Brucella abortus strain 19.

Cell-mediated immune responses in cattle naturally infected with strains of Brucella abortus and in cattle vaccinated with B abortus strain 19 during calfhood were studied by an in vitro lymphocyte-stimulation procedure. Lymphocytes were prepared from peripheral bovine blood by the Ficoll-diatrizoate technique, suspended in RPMI-1640 medium (1.5 X 10(6) lymphocytes/ml), cultured with B abortus-soluble antigen or phytohemagglutinin, and incubated for 6 days. Sixteen hours prior to termination of incubation, cultures were labeled with 1 muCi of [3H]thymidine (3HdT) and, after harvesting, assayed for 3HdT incorporation into DNA by liquid scintillation spectrometry. Lymphocytes from cattle with bacteriologically confirmed isolation of B abortus underwent a significantly higher lymphocyte stimulation with B abortus-soluble antigen than did cattle vaccinated with B abortus strain 19 during calfhood (P less than 0.005). Standard seroagglutination tests were conducted simultaneously with lymphocyte-stimulation tests, but there was no apparent correlation between levels of humoral antibodies and the cell-mediated immune responses as measured by in vitro specific lymphocyte stimulation.

Agglutination Tests↗
PubMed1978

In vitro stimulation of bovine peripheral blood lymphocytes: effect of short-term storage of blood prior to lymphocyte culture.

Storage of peripheral blood from Mycobacterium bovis-sensitized cattle from 1 to 48 hours at 4, 22, and 37 C was shown not to alter markedly the lymphocyte blastogenic response to M bovis-purified protein derivative. Concanavalin A-induced lymphocyte mitogenic responses were unaffected by storage of blood for 1, 24, or 48 hours at 22 C and 37 C; however, storage of blood for 48 hours at 4 C significantly lowered (P less than 0.05) mitogenic responses to concanavalin A, as compared with responses to blood kept at 22 C. Mononuclear cell recovery from stored blood at all temperatures was markedly less than that from freshly drawn blood samples. Cell recoveries were most affected by storage of blood at 4 C and 37 C.

Animals↗
PubMed1978

In vitro stimulation of bovine peripheral blood lymphocytes: analysis of variation of lymphocyte blastogenic response in normal dairy cattle.

Lymphocyte immunostimulation tests were performed on 12 lactating dairy cows once every 2 weeks for 1 year. The results indicated that the greatest response of peripheral blood lymphocytes to mitogens occurred in 4- to 6-year-old cows in the month of August and in cows at 2 months before the end of the gestation and again at 1 month after parturition. The least lymphocyte mitogenic response was shown in 7- to 9-year-old cows in the month of February or at parturition and 2 to 4 months after parturition. The magnitude of variations in lymphocyte blastogenic response is reported.

Age Factors↗
PubMed1978

Cell-mediated immune responses in swine from a herd infected with Brucella suis.

Cell-mediated immune (CMI) responses in swine naturally infected with Brucella suis biotype 3, swine suckling an infected sow and Brucella-noninfected swine were studied by an in vitro lymphocyte transformation procedure. The antigen used was a soluble antigen prepared from killed cells of B suis biotype 3. Lymphocytes were prepared from peripheral swine blood by the Ficoll-Hypaque technique, suspended in RPMI-1640 medium (1.5 X 10(6) lymphocytes/ml), cultured with B suis-soluble antigen or concanconcanavalin A, and incubated for 6 days. Sixteen hours prior to termination of incubation, cultures were labeled with 1 muCi of [3H]thymidine and, after harvesting, were assayed for [3H]thymidine incorporation into DNA by liquid scintillation spectrometry. Agglutination tests were conducted on sera collected simultaneously with samples for lymphocyte-stimulation tests. The B suis-soluble antigen elicited specific stimulation in lymphocytes from infected pigs. On a group basis, there was high correlation between the amount of serum antibodies and specific lymphocyte stimulation, but on an individual animal basis, there was little correlation of the results of both systems in infected swine. There was high correlation between recovery of Brucella from the tissues of animals and the degree of CMI response. Suckling pigs from an infected sow did not develop CMI responses, as measured by our system.

Agglutination Tests↗
PubMed1977

Tympanostomy tube protection with ear plugs.

Protection by ear plugs from water-borne infection was evaluated in 35 patients with "tympanostomy" tubes, tympanic membrane perforations, or mastoid bowls. Stock and custom-made ear plugs were found to be equally effective up to four months during a period of frequent swimming and bathing activities. Infections were only noted to occur in those patients who did not follow instructions on appropriate use of the plugs.

Adolescent↗
PubMed1977

Evidence that B-lymphocytes carry the nuclear pocket abnormality associated with bovine leukemia virus infection.

Peripheral blood lymphocytes from 3 cows with persistent lymphocytosis were separated on nylon wool columns into nylon wool-adherent and nonadherent populations. The percentage of cells coated with surface immunoglobulin (B-cells) and the frequency of lymphocytic nuclear pockets in each sub-population were then determined. In each case the adherent population consisted predominantly of B-cells with an increased nuclear pocket frequency, whereas the nonadherent cells were 98.99% negative for surface immunoglobulin (non-B-cells) and contained essentially no nuclear pockets. These findings provided additional evidence that the B-subpopulation of cells was highly involved in bovine leukemia oncogenesis.

Animals↗
PubMed1977

Detection of bovine leukemia virus in B-lymphocytes by the syncytia induction assay.

Bovine peripheral blood lymphocytes (PBL's) from 3 cows and 1 steer infected with bovine leukemia virus (BLV) were separated by fractionation through nylon wool columns into nylon-adherent and nonadherent cell populations. Nylon-adherent cells were enriched in B-lymphocytes, as determined by the presence of surface membrane immunoglobulins (slg), whereas nylon-nonadherent cells or "non-B-lymphocytes" contained few slg-bearing cells. PBL's and separated B- and non-B-lymphocyte populations were assayed for the presence of BLV by the induction of syncytia in bovine embryonic spleen cells. PBL's and B-lymphocyte populations both produced many syncytia, whereas non-B-lymphocytes yielded few or no syncytia. The specificity of syncytia formation by anti-BLV serum. PBL's from 2 control animals were negative for syncytia induction. This study presents further evidence that B-lymphocytes are the target cells for BLV infection.

Animals↗
PubMed1977

Epidemiology of mycobacterial lymphadenitis in an Idaho swine herd.

A study of Mycobacterium avium infected swine in an Idaho herd was made to obtain information on morbidity and to evaluate some control measures. Of 867 pigs slaughtered during a 30-day period in May and June, 1974, 100 carcasses were condemned or passed for cooking and 406 carcasses had lesions in one lymph node and were passed without restriction. Mycobacteriologic examinations were made on 33 pigs which were tuberculin tested. Mycobacterium avium was isolated from 21 of 26 tuberculin positive pigs and from 4 to 7 tuberculin negative pigs. Lymphocyte stimulation tests were completed for 12 pigs. Positive results were observed in 11 and M. avium was isolated from 7. Mycobacterium avium serotypes 1,2,4,8, and 9 were identified.

Animals↗
PubMed1977

Oxygen exchange in a simulated trout gill secondary lamella.

The complex blood flow patterns occurring in a trout secondary lamella were computed from a theoretical electrical model consisting of a two-dimensional array of unitary resistances representing the blood channels of the lamella. Estimates of oxygen uptake from water to blood were made by means of the standard conductance equations for oxygen and values from the literature for blood and water PO2's in trout. The results were plotted as contour charts of blood and water PO2, O2 transfer, and blood flow. According to the results of various manipulations of this model, oxygen exchange across a given lamella will be largely unaffected by changes in the overall shape of the lamella. However, the model predicted that oxygen exchange would be greatly reduced if 1) the basal pillar cell channels were denied access to the respiratory water flow, 2) pillar cell contraction were to force blood into the larger-diameter marginal channels, or 3) the blood flow rate were to be increased, regardless of a concomitant increase in water flow. These predictions are discussed in terms of current theories of gas exchange in teleost gills.

Animals↗
PubMed1977

Evidence for the replication of bovine leukemia virus in the B lymphocytes.

Bovine peripheral blood lymphocytes from a cow with persistent lymphocytosis were separated on nylon wool columns into nylon-adherent and nonadherent populations. Nylon-adherent cells were highly enriched for surface immunoglobulin (SIg) bearing B lymphocytes (95.5%) and nonadherent cells for SIg negative non-B cells, presumably T lymphocytes (96.3%). The B lymphocytes were found to be the major producers for bovine leukemia virus. A total of 39% of the B-enriched cells, surviving after 72 hours in culture, produced bovine leukemia virus as compared with 0.5% of the non-B cells.

Animals↗
PubMed1977

Skin testing, fecal culture, and lymphocyte immunostimulation in cattle inoculated with Mycobacterium paratuberculosis.

Fourteen calves at 21 days of age were experimentally inoculated with 100 mg (wet weight) of Mycobacterium paratuberculosis. Three calves were inoculated orally, 4 intravenously, and 7 subcutaneously. Lymphocyte immunostimulation, fecal culture, and intradermal tuberculin skin testing were done between 112 to 150 days following exposure. Lymphocyte immunostimulation test results, conducted at 112 days after inoculation, showed all animals positive to Mycobacterium avium purified protein derivative. Fecal culture results, taken at 120 days after inoculation, showed that 2 of 3 animals inoculated intravenously were positive, whereas only 2 of 7 inoculated subcutaneously were positive (8 of 14 total were positive). Intradermal skin testing results at 150 days with M avium purified protein derivative showed 13 of the 14 calves were positive. Calves were examined at necropsy 153 days after inoculation, and M paratuberculosis was isolated from tissues of each of the 14 calves.

Animals↗
PubMed1977

In vitro stimulation of bovine peripheral blood lymphocytes: suppression of phytomitogen and specific antigen lymphocyte responses by aflatoxin.

The effects of aflatoxin B1 on responses of the peripheral blood lymphocytes (PBL) of 2 normal animals to phytohemagglutinin, concanavalin-A, and pokeweed mitogen and of the PBL of 2 Mycobacterium bovis-infected animals to phytohemagglutinin and purified protein derivative of M bovis (PPD) were studied. Aflatoxin concentrations of greater than or equal to 10 microgram/ml significantly suppressed the lymphocyte response of normal animals to the phytomitogens. Lymphocyte response of M bovis-infected animals to specific antigen PPD was significantly suppressed at aflatoxin concentration of 0.5 microgram/ml. Fifty- to 100-fold higher concentrations of aflatoxin were required to produce 50% suppression of lymphocyte response to phytomitogens, as compared with that produced to PPD.

Aflatoxins↗
PubMed1976

Effects of hemodialysis on hearing threshold.

71 chronic renal failure patients undergoing long-term hemodialysis were evaluated for the effects of a dialysis event on hearing function. Osmotically active serum constituents were examined for relationship to fluctuating hearing threshold levels. Reliabiliity of hearing levels was found to be better in those patients tested without an intervening dialysis event. Those patients tested before and after hemodialysis demonstrated greater hearing fluctuation than those patients evaluated between dialysis events. This threshold fluctuation was unrelated to serum urea nitrogen, creatinine, K+, Na+, Ca++, or glucose. It was concluded that hearing test reliability in dialyzing renal patients is resonably good, but test results are likely to be more consistent if testing is accomplished a number of hour after a given dialysis event. Contrary to a number of reports in the recent literature, no direct relationship between hearing level fluctuation and fluctuation in individual osmotically active serum constituents appeared to be present.

Adult↗