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Biomedical subjects

R J Markham

Publications and source records attributed to R J Markham.

At least 37 records · Page 2Linked to original sources
PubMed1985

Identification of an immunosuppressive protein in bovine seminal plasma with activity against bovine lymphocytes.

Seminal plasma was determined to have immunosuppressive activities in vitro on Concanavalin A-induced blastogenesis of bovine lymphocytes. This immunosuppressive activity was isolated and characterized using a pool of seminal plasma from five bulls. The immunosuppressive activity was associated with seminal plasma proteins of less than 50,000 daltons and also with those of approximately 150,000 daltons. The 150,000-dalton proteins were precipitable at 33% saturation with ammonium sulfate and with an antibody to a Sephadex G-200 chromatographic fraction of seminal plasma. The immunosuppressive activity of the less than 50,000 dalton proteins was lost upon chromatography on Sephadex G-25. This suggests that interaction of several components of low molecular weight might be necessary for this inhibitory activity to be expressed.

Animals↗
PubMed1985

Immunosuppressive activity of bovine follicular fluid on bovine T lymphocytes in vitro.

Follicular fluid from bovine follicles at various stages of the estrous cycle and cysts were tested in vitro for immunosuppressive activity. Mitogen-stimulated lymphocyte assays and the mixed lymphocyte reaction were used as test procedures and thymidine uptake was monitored. Follicular fluid and cyst fluid inhibited the deoxyribonucleic acid synthesis response of bovine lymphocytes to mitogenic and antigenic stimulation. The nature of the suppression varied with the mitogen or antigen assay used, with the estrual stage, with size of follicle within the diestrual stage, and with the type of ovarian cyst. Blood sera from estrual or diestrual cows were not immunosuppressive. Heating (56 degrees C for 30 min) follicular fluid from normal follicles and cysts destroyed most of its suppressive activity toward Concanavalin A-stimulated lymphocytes but did not suppress that in luteal cyst fluid. The suppressive activity in follicular fluid toward phytohemagglutinin-stimulated lymphocytes was more stable to heat than that against Concanavalin A-stimulated lymphocytes. Because the immunosuppressive activity in follicular fluid was heat labile, estrogen, progesterone, and other steroids were not the active suppressive molecules. Proposed roles for these immunosuppressive substances are hypothesized in preventing autoantibody formation to the zona pellucida and in the inflammatory reaction leading to ovulation.

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PubMed1985

Release of immunosuppressive substances from tissue culture cells infected with bovine viral diarrhea virus.

Bovine fetal lung tissue culture cells were infected with bovine viral diarrhea virus. The cells released substances into the supernatant fluid that suppressed the proliferative response of bovine peripheral blood mononuclear cells which had been stimulated with concanavalin A. Activity could be found in low molecular weight fractions (less than or equal to 2,000 daltons). During the assay, these fractions were required to inhibit the response of leukocytes to concanavalin A. Addition of indomethacin to the infected tissue culture cells inhibited generation of immunosuppressive supernatants; addition of indomethacin to the suppressive supernatants did not block their activity. The possible involvement of prostaglandins in this immunosuppressive activity is discussed.

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PubMed1985

Pulmonary response to intratracheal challenge with Pasteurella haemolytica and Pasteurella multocida.

Calves were inoculated intratracheally with 5 X 10(7), 5 X 10(8), or 5 X 10(9) colony forming units of either 18-hour stationary phase cultures or 4-hour log phase cultures of Pasteurella haemolytica. The log phase culture at all concentrations produced more severe clinical signs, hematological changes and pulmonary lesions at postmortem examination than did the corresponding stationary phase culture. More severe effects were seen with the larger doses especially with the log phase culture. Fibrinous bronchopneumonia with focal or multifocal necrosis was consistently produced by both the stationary and log phase cultures. To determine if this lesion was peculiar to P. haemolytica or whether it could be produced generally by rapidly growing Gram negative organisms, a 4-hour log phase culture of Pasteurella multocida was prepared in an identical manner to that used for the culture of P. haemolytica and given to calves intratracheally at the high bacterial dose (5 X 10(9]. The P. haemolytica produced more severe clinical, hematological and morphological changes than did the P. multocida. The lesions observed with P. multocida differed morphologically from those of P. haemolytica; there was a suppurative exudative component and minimal to no necrosis with P. multocida. It appears that an important pathogenic principle is produced by the rapidly growing P. haemolytica that causes it to produce a more severe clinical disease and more necrotizing pulmonary lesions than P. multocida.

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PubMed1985

Serologic studies of bovine respiratory syncytial virus in Minnesota cattle.

Serum antibody titers to bovine respiratory syncytial virus were determined for 559 cattle. Serum samples were obtained through the Minnesota State-Federal Brucellosis Laboratory and were collected over a 1-year period. Results of this study revealed an antibody prevalence of 65.5% to bovine respiratory syncytial virus. The distribution of antibody titers is presented, as well as analysis of titers based on breed, sex, and age of the cattle.

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PubMed1984

Agar gel immunodiffusion test for diagnosis of clinical paratuberculosis in cattle.

During a 19-month period, the agar gel immunodiffusion (AGID) test was used as an aid in differential diagnosis of paratuberculosis in 51 cattle with a history of chronic weight loss and/or chronic diarrhea. Thirty-three cattle were AGID test-positive for paratuberculosis. Twenty-eight cattle (87.5%) yielded Mycobacterium paratuberculosis from bacterial culture of feces. Four cattle were confirmed as having paratuberculosis on necropsy. One had a negative fecal culture but was lost to follow-up. Thus, 32 of the 33 AGID test-positive cattle (96.9%) were confirmed as paratuberculous by culture or necropsy. Of the 18 cattle that were AGID test-negative, 17 (94%) also were culture-negative after 12 to 20 weeks' incubation of the culture tubes. Direct fecal smears from 29 confirmed paratuberculous cattle were examined. Twenty-three (79.3%) had smears positive for M paratuberculosis. Fifteen culture-negative cattle were examined by direct smear; the results were negative for all.

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PubMed1984

Enzyme-linked immunosorbent assay and indirect haemagglutination techniques for measurement of antibody responses to Eimeria tenella in experimentally infected chickens.

An indirect haemagglutination test (IHA) and ELISA technique were developed to detect antibodies against Eimeria tenella. The ELISA technique was relatively easy to perform, more sensitive than the IHA test, and needed only a fraction of the antigen required for IHA. The highest titers using ELISA were 1:16,384 compared to the IHA titers of 1:64 for the same sera. The ELISA titers depended upon the age of the birds when they were infected, the number of oocysts inoculated and the number of inoculations. Immunodeficient birds (cyclophosphamide-treated), when inoculated with several doses of oocysts of E. tenella (350, 3,000, 30,000) showed no IHA or ELISA antibody titers. The immuno-competent chickens of the same age, which received identical doses of oocysts responded with readily detectable antibody levels. Chickens inoculated with E. maxima or E. necatrix had sera titers of 1:50 or 1:400, respectively, when reacted with E. tenella antigen. The E. tenella inoculated birds had titers as high as 1:3,200 with the same antigen.

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PubMed1983

The pathology of experimental Corynebacterium equi infection in foals following intrabronchial challenge.

Six foals were inoculated intrabronchially with a suspension of Corynebacterium equi. Six weeks before this challenge, three foals were vaccinated with a C. equi bacterin. Three foals were unvaccinated controls. All foals developed a severe bronchopneumonia in the inoculated lung, indicating that vaccination was not protective. Three foals (two vaccinated, one control) were killed eight to nine days after infection. One control died on day 9 with lesions of disseminated intravascular coagulation. The remaining two foals (one vaccinated, one control) were killed on day 17. C. equi was cultured in large numbers from affected lung and bronchial lymph nodes, and in smaller numbers from unaffected lung, spleen, and liver in all foals. In the 8- to 9-day-old lung lesions, the alveoli were filled with macrophages, neutrophils, and multinucleate giant cells and most contained numerous C. equi. The few foci of alveolar necrosis were associated with groups of bacteria-laden macrophages undergoing degeneration. In the lesions of 17-day duration, there was extensive parenchymal destruction with little fibrous tissue reaction. Lesions common to both groups included hyperplastic bronchiolitis, pulmonary edema, and perivascular lymphocytic cuffs and a pyogranulomatous lymphadenitis in bronchial nodes. One vaccinated foal had a microscopic pyogranulomatous colitis. The lesions in the experimentally infected foals are compared with those in naturally infected foals and discussed in terms of likely pathogenetic mechanisms involved in C. equi pneumonia in foals.

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PubMed1983

The pathology of experimental Corynebacterium equi infection in foals following intragastric challenge.

The intragastric inoculation of a suspension of Corynebacterium equi on five consecutive days induced severe ulcerative colitis, typhlitis, and lymphadenitis of colonic and cecal nodes in two ponies necropsied three weeks after infection. No gross lesions were observed in two ponies necropsied ten days after infection. A single inoculum of equivalent size failed to induce gross lesions in four ponies killed at ten or 20 days after infection. Microscopic lesions consistent with early C. equi infection of Peyer's patches were seen in two of the ponies killed ten days after infection. Only one small pulmonary abscess occurred in one foal, suggesting that intestinal lesions are not likely the usual precursor of pulmonary disease in naturally infected foals. The gross and microscopic lesions in the experimentally infected ponies were typical of the intestinal form of naturally occurring C. equi associated disease in foals.

Animals↗
PubMed1982

Cytotoxic effect of Pasteurella haemolytica on bovine polymorphonuclear leukocytes and impaired production of chemotactic factors by Pasteurella haemolytica-infected alveolar macrophages.

Pasteurella haemolytica exerted a cytotoxic effect on bovine polymorphonuclear neutrophil leukocytes. This effect was less than that seen with cultured alveolar macrophages or peripheral blood monocytes. When alveolar macrophages were cultured with Pasteurella haemolytica, macrophages produced less chemotactic factors for polymorphonuclear leukocytes than did noninfected controls. This effect was reversible, in that removal of the bacteria permitted remaining macrophages to elaborate more chemotactic factors than was seen in controls. The possible consequences of this impairment of function of alveolar macrophages are discussed.

Animals↗
PubMed1980

Response of calves to lung challenge exposure with Pasteurella haemolytica after parenteral or pulmonary immunization.

In 3 experiments, calves were vaccinated by intrabronchial or subcutaneous injection of formalinized Pasteurella haemolytica. Immunization was evaluated by assessing the clinical and pathologic responses to pulmonary challenge exposure with live homologous bacteria. Serum and bronchoalveolar washings were titrated for antibody by indirect (antiglobulin) bacterial agglutination. Response to challenge exposure was determined by increased rectal temperature and faster respiratory rate. In all experiments, the most obvious clinical change occurred in challenge-exposed calves which had been vaccinated by the subcutaneous injection of killed P haemolytica with added adjuvant. Also, macroscopic pulmonic lesions were recorded most frequently in calves vaccinated by this route. In all instances, immunization resulted in elevated anti-P haemolytica titers both in lung and serum.

Animals↗
PubMed1980

Lymphocyte immunostimulation in the diagnosis of Corynebacterium equi pneumonia of foals.

A lymphocyte stimulation test using antigens of Corynebacterium equi was used to compare the response of peripheral blood lymphocytes from foals with C equi pneumonia with those of clinically normal foals and adult horses. The test clearly distinguished infected foals from normal foals when tested in animals less than or equal to 2 months old. After the 2nd month, stimulation response from individual normal foals sometimes exceed those from infected foals, but mean stimulation response to C equi antigens was significantly (P less than 0.025) greater in 3- to 5-month-old infected foals when compared with mean values of 3- to 5-month-old normal foals. Mean stimulation responses in 5- to 7-month-old foals, which had recovered from C equi pneumonia, could not be distinguished from mean responses of normal foals. The test could still, however, be used diagnostically in foals greater than 2 months of age if stimulation responses were low. The test indicated the great extent of exposure to C equi in the normal horse population.

Animals↗
PubMed1980

Interaction between Pasteurella haemolytica and bovine alveolar macrophages: cytotoxic effect on macrophages and impaired phagocytosis.

Cultured bovine alveolar macrophages phagocytosed formalized 125I-labeled Pasteurella haemolytica organisms poorly when compared with uptake of an identical number of radiolabeled Yersinia enterocolitica organisms. The presence of immune serum enhanced uptake of P haemolytica, yet at high bacteria-to-macrophage ratios, a significant positive correlation existed between uptake and loss of cells from coverslips. This phenomenon was not observed with Y enterocolitica. While culture supernatant from P haemolytica either impaired phagocytosis or were cytotoxic to cultured macrophages, supernatant from Y enterocolitica did not show this effect. The observation of an apparent deterimental effect on bovine alveolar macrophages after uptake of P haemolytica may be used to explain events occurring in pneumonic pasteurellosis in cattle and may help in the development of immunizaiton techniques.

Animals↗
PubMed1980

Influence of bronchoalveolar washing supernatants and stimulated lymphocyte supernatants on uptake of Pasteurella haemolytica by cultured bovine alveolar macrophages.

Bovine alveolar macrophages cultured for 12 hours with normal bovine bronchoalveolar washing supernatants (BWS) showed impaired phagocytosis of Pasteurella haemolytica when compared with phagocytosis in control cultures. Such impairment was not observed when another gram-negative bacillus, Yersinia enterocolitica, was used. The BWS from calves inoculated subcutaneously or intrabronchially with P haemolytica inhibited uptake of P haemolytica when BWS were incubated with the bacteria prior to addition to macrophage cultures. However, serum from these calves had pronounced opsonizing activity. Supernatants from stimulated and nonstimulated bovine peripheral blood lymphocyte cultures also inhibited phagocytosis of P haemolytica.

Animals↗
PubMed1980

Experimental studies on the pathogenesis of Corynebacterium equi infection in foals.

Four month-old foals were infected orally with 75 mL of a suspension of 5.0 x 10(8)Corynebacterium equi per mL. Two foals were killed after ten days and had scanty number of C. equi in the caeco-colic lymph nodes. No C. equi were recovered from the other two foals, killed 20 days after infection. No gross pathological change was detected in these four foals, although mild microscopic lesions were seen in the ileum of one foal. Results of lymphocyte blastogenesis using peripheral blood lymphocytes and C. equi antigens showed, however, that lymphocytes became sensitized to C. equi following this challenge. In a second experiment four month-old foals were given orally the same dose of organisms but on five consecutive days. Two foals were killed ten days after infection and showed mild histological changes in the large bowel mucosa and C. equi could be recovered from all intestinal lymph nodes cultured. In one of these foals moderate numbers of C. equi were present in the bronchial lymph node. Of the other two foals, one died after 22 days with severe ulcerative enterocolitis and intestinal lymphadenitis. Only one small pulmonary abscess was detected despite large numbers of C. equi in the lungs. The other foal developed similar intestinal changes and was euthanized 25 days after infection. No C. equi were detected in the lungs or bronchial lymph node. Lymphocyte blastogenesis in these animals showed a rapid rise in response to C. equi antigens. These studies suggest that C. equi pneumonia in foals does not always arise from an intestinal infection, that minor intestinal infection causes a cellular immune response and that massive exposure of the bowel over a sustained period is necessary to induce intestinal lesions.

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