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Biomedical subjects

J A Ellis

Publications and source records attributed to J A Ellis.

At least 127 records · Page 7Linked to original sources
PubMed1991

Antigen specificity and activity of ovine antibodies induced by immunization with Corynebacterium pseudotuberculosis culture filtrate.

Sheep were immunized three times with a vaccine composed of filtrate from a 36 h culture of Corynebacterium pseudotuberculosis and a block polymer adjuvant. Immunization resulted in the development of exotoxin-neutralizing antibody. This corresponded to the recognition of a 31.6 kDa protein on sequential immunoblots of ammonium sulfate-precipitated filtrate. In addition sera from vaccinated sheep recognized at least eight bacterial cellular antigens on immunoblots of ether-extracted C. pseudotuberculosis, including bands of 12, 25.1, 31.6, 36.3, 39.8, 63.1, 70, 75 or 79.4 kDa. Sera from these sheep altered the colony growth characteristics of C. pseudotuberculosis in vitro. These results indicate that immunization with soluble C. pseudotuberculosis in vitro. These results indicate that immunization with soluble C. pseudotuberculosis antigen preparations that have been used in toxoid vaccines induces antibody responses to numerous cellular antigens in addition to exotoxin and suggest that serologically mediated antibacterial effects could be an important component in the protection from disease that has been reported following immunization with C. pseudotuberculosis toxoids.

Animals↗
PubMed1991

Analyses of ovine corpora lutea for tumor necrosis factor mRNA and bioactivity during prostaglandin-induced luteolysis.

It has been suggested that tumor necrosis factor (TNF) participates in the mechanism of regression of the corpus luteum. We measured luteal expression of TNF alpha mRNA and biological activity during prostaglandin-induced luteolysis in sheep. Initiation of functional luteolysis was marked by a sharp decline in concentrations of progesterone in luteal tissue beginning 4 h after administration of luteolysin. Structural regression of corpora lutea was manifested by a reduction in glandular weight at 16 h. A luteal cytotoxic factor with TNF alpha-like bioactivity was isolated after the decrease in tissue progesterone had occurred, but before evidence of luteal resorption. We were unable to detect temporal alterations in TNF alpha mRNA in luteal samples by classical Northern blot or in situ hybridization analyses. These results imply that luteal TNF alpha is derived primarily as a preformed entity from an extraovarian source, such as infiltrating leukocytes. These results raise the possibility that this cytokine might not be involved in the early stages of luteal regression in the ewe, yet could play a secondary role, perhaps in the subsequent opsonization and removal of degenerating cells.

Animals↗
PubMed1991

Differential induction of tumor necrosis factor alpha in ovine pulmonary alveolar macrophages following infection with Corynebacterium pseudotuberculosis, Pasteurella haemolytica, or lentiviruses.

Soluble mediators such as tumor necrosis factor alpha (TNF-alpha) may be important in the pathogenesis of many chronic pulmonary infections. We examined the ability of Corynebacterium pseudotuberculosis, Pasteurella haemolytica, and ovine lentiviruses (OvLV) to induce TNF-alpha secretion by pulmonary alveolar macrophages (PAM). Bronchoalveolar lavage cells, composed of greater than 90% PAM, were obtained from normal sheep. Bronchoalveolar lavage cells were cultured for 2, 24, 48, 72, or 168 h in endotoxin-free RPMI medium (with 10% autologous serum) or in medium containing one of the following additives: lipopolysaccharide, 1-micron polystyrene beads, C. pseudotuberculosis, P. haemolytica, or one of two plaque-cloned OvLV, 85/28 or 85/34. Lipopolysaccharide, C. pseudotuberculosis, and P. haemolytica induced TNF-alpha activity in PAM cultures as early as 2 h after inoculation, as assessed by a colorimetric cytotoxicity assay. This activity could be blocked by rabbit anti-recombinant bovine TNF-alpha serum. In contrast, medium alone, polystyrene beads, and productive infection by OvLV did not induce TNF-alpha activity in PAM cultures. Bacterial pathogens which infect pulmonary macrophages may elicit the secretion of TNF-alpha within the lungs and lead to the cachectic state associated with chronic pneumonia.

Animals↗
PubMed1991

Cytokine modulation of the interaction between bluetongue virus and endothelial cells in vitro.

An in vitro model was developed to examine the interaction between endothelial cells and the host inflammatory response in bluetongue virus (BTV) infections. Whole cell enzyme-linked immunosorbent assays, a tritiated thymidine uptake assay, and a colorimetric assay of mitochondrial function were used to assess how four cytokines (interleukin-1, interleukin-2, interferon-gamma, and tumor necrosis factor-alpha) affect endothelial cell metabolism and susceptibility to BTV infection. Concurrent alterations in major histocompatibility complex (MHC) antigen expression were also examined. BTV infection suppressed target cell mitochondrial function and DNA synthesis and enhanced MHC class I expression. Interferon-gamma and tumor necrosis factor alpha suppressed viral antigen expression and were synergistic early in the infection. Interferon gamma enhanced MHC class I and induced MHC class II antigen expression in both BTV infected and uninfected endothelial cells. The other cytokines had minimal effect on endothelial cell surface antigen expression, although interleukin-1 (IL-1) did inhibit cell growth. Infected endothelial cell cultures produced interferon at 20 hours and 40 hours after infection. Electron microscopic analysis confirmed previous findings in other cell lines regarding BTV morphogenesis in endothelial cells, the putative target cell population in vivo.

Animals↗
PubMed1991

Coping with adolescent cancer: it's a matter of adaptation.

Adolescents with cancer face many stresses that challenge their ability to cope. Using the framework of the Roy model, common adaptation problems and nursing interventions are discussed as they pertain to adolescents with cancer.

Adaptation, Psychological↗
PubMed1991

Effects on aflatoxin M1 residues in milk by addition of hydrated sodium calcium aluminosilicate to aflatoxin-contaminated diets of dairy cows.

Hydrated sodium calcium aluminosilicate (HSCAS), an anticaking agent for agricultural feeds, was added to aflatoxin (AF)-contaminated diets of 3 lactating dairy cows and evaluated for its potential to reduce aflatoxin M1 (AFM1) residues in milk. During phase I, cows were fed alternating diets that consisted of 200 micrograms of AF/kg of feed for 7 days, 0.5% HSCAS plus 200 micrograms of AF/kg of feed for 7 days, and feed with the HSCAS removed for a final 7 days. The AFM1 milk concentrations from the intervals with HSCAS added to diets were compared with those times when HSCAS was absent. The presence of 0.5% HSCAS in feed containing 200 micrograms of AF/kg reduced AFM1 secretion into the milk by an average of 0.44 micrograms/L (from pretreatment of 1.85 micrograms/L to 1.41 micrograms/L with HSCAS, a 24% reduction). Following a 10-day period of noncontaminated feed consumption and no AFM1 residues in the milk, phase II of the study was begun. The same experimental design as phase I was used, but the dosages of HSCAS and AF were changed to 1.0% and 100 micrograms/kg of feed, respectively. The addition of 1.0% HSCAS in feed containing 100 micrograms of AF/kg decreased AFM1 content in the milk by an average of 0.40 micrograms/L (from a pretreatment of 0.91 micrograms/L to 0.51 micrograms/L when HSCAS was present, a 44% reduction). These findings suggest that HSCAS, a high-affinity sorbent compound for AF in vitro, is capable of reducing the secretion of AFM1 into milk.

Aflatoxin M1↗
PubMed1990

Differential antibody responses to Corynebacterium pseudotuberculosis in sheep with naturally acquired caseous lymphadenitis.

Enzyme-linked immunosorbent assays (ELISA) with Corynebacterium pseudotuberculosis cell wall and bacteria-free supernatant with exotoxin preparations as antigens, and hemolysis inhibition tests were used to detect antibodies in the sera of adult range sheep with naturally acquired caseous lymphadenitis (CL). The extent and severity of lesions were quantitated on the basis of a lesion score, derived from an examination of the carcass (peripheral lymphoid tissue) and viscera (including internal lymphoid tissue) at the time of slaughter. The overall prevalence of C pseudotuberculosis-positive CL lesions in 104 sheep was 31.7%. The cell wall ELISA detected antibodies in 96.9% (32/33) of sheep with C pseudotuberculosis-positive CL lesions. The exotoxin ELISA detected antibodies in 84.8% (28/33) of positive sheep in the same group. Both ELISA resulted in a high number of apparent false-positives, with 64.7% and 49.2%, respectively, positive optical density (OD) values in sheep with no gross CL lesions and no apparent C pseudotuberculosis infection. There was no significant relationship between the extent of lesion development (lesion score) and OD values in both cell wall (r = 0.472) and exotoxin (r = 0.464) ELISA. Similarly, there was no significant relationship between the titer of antitoxin antibodies, as measured by the hemolysis inhibition test, and the extent of disease. These investigations indicate that those ELISA that use crude C pseudotuberculosis antigens are of questionable utility in the field, where C pseudotuberculosis infection is endemic in many sheep populations. Furthermore, these studies suggest that antibodies that are reactive with components of C pseudotuberculosis and that develop in response to infection may have little impact on the recovery of the host.

Animals↗
PubMed1990

Clinical and immunologic response of cattle to administration of a vaccine containing modified-live bovine respiratory syncytial virus.

Healthy yearling beef and dairy cattle were inoculated with a vaccine containing modified-live bovine respiratory syncytial virus (ML-BRSV), and sequential changes in clinical signs of disease, blood leukocyte subsets, BRSV-specific antibody titer, and in vitro lymphocyte blastogenic responses were monitored. Vaccination with ML-BRSV did not cause pyrexia, local or systemic hypersensitivity reaction, or respiratory tract disease. Episodes of leukopenia, abnormalities in lymphocyte subsets, or depression of phytomitogen-induced blastogenic responses were not observed subsequent to vaccination. Exposure to ML-BRSV resulted in at least a 16-fold increase in serum neutralizing antibody titer, with no increase seen in nonvaccinated contact controls. Significant BRSV-specific lymphocyte blastogenic responses were not detected, using one dose of several BRSV antigen preparations in a whole blood culturing system.

Animals↗
PubMed1990

Identification and characterization of monoclonal antibodies reactive with bovine, caprine and ovine T-lymphocyte determinants by flow microfluorimetry.

Comparative flow microfluorimetric (FMF) analysis was used to identify and characterize 27 monoclonal antibodies (MoAbs) reactive with bovine T-lymphocytes. Determinants present on all circulating T-lymphocytes were recognized by 11 MoAbs, 8 of which blocked E rosette formation. Determinants present on only the BoCD4+ T-lymphocyte subset were detected by 9 MoAbs, while determinants restricted to the BoCD8+ T-lymphocyte subset were recognized by 7 MoAbs. Competitive labeling experiments demonstrated that determinants recognized by subset-specific MoAbs were present on BoCD4 or BoCD8 molecules. Comparative studies revealed that some determinants, both pan-T specific and subset-specific, were conserved on homologous (orthologous) molecules expressed on leukocytes from other species of ruminants. Polymorphism was evident with several determinants.

Animals↗
PubMed1990

T lymphocyte subset alterations following bluetongue virus infection in sheep and cattle.

To determine potential mechanisms of differential disease expression in ruminants infected with bluetongue virus (BTV), clinically normal, BTV-seronegative, yearling sheep and cattle were infected subcutaneously with a standardized insect-source inoculum of BTV serotype 17 (BTV-17) (three infected and one contact control each) or animal adapted BTV serotype 10 (BTV-10) (three sheep only). BTV was isolated from peripheral blood cell components of infected sheep and cattle and all infected animals showed evidence of seroconversion by 14 days post infection (PI). Sheep infected with both serotypes of BTV developed pyrexia, oral lesions, and leukopenia which were most severe on days 7-8 PI. Analysis of peripheral blood mononuclear leukocytes with specific monoclonal antibodies and flow cytometry revealed panlymphocytopenia on day 7 PI. This response was further characterized by an increase in the CD4/CD8 ratio (greater than 3) resultant from a greater decrease in absolute numbers of circulating SBU-T8(CD8+) ("cytotoxic/suppressor") lymphocytes compared to SBU-T4 (CD4)+ ("helper") lymphocytes. SBU-T19+ lymphocytes were also decreased below baseline values on days 5-14 post infection. On day 14 PI there were increased CD8+ lymphocytes and decreased CD4/CD8 ratios (approximately 0.6) in these sheep. Clinical and hematologic changes in cattle infected with BTV-17 were minimal and consisted of mild pyrexia (rectal temperature 103 degrees F) on day 9 PI in two of three infected animals and mild leukopenia on several days PI in one animal. This leukopenia was the result of a pan T lymphocytopenia with CD4/CD8 ratios in the expected range (1-2). Similar to infected sheep, infected cattle did have a shift (decrease, approximately 0.8) in the peripheral CD4/CD8 ratio associated with an increase in circulating BoT8 (CD8)+ lymphocytes on day 14 post infection. Lymphocytes in the peripheral blood of all sheep and cattle infected with BTV-17 proliferated in vitro in response to purified BTV-17. These results confirm and extend those of previous studies that indicate species differences in the hematologic response to an equivalent BTV infection in domestic ruminants.

Animals↗
PubMed1989

Studies on the electron-transfer mechanism of the human neutrophil NADPH oxidase.

A superoxide-generating NADPH oxidase was solubilized from phorbol 12-myristate 13-acetate-activated human neutrophils with a mixture of sodium deoxycholate (0.125%, w/v) and Lubrol-PX (0.125%, v/v). The solubilized preparation contained FAD (577 pmol/mg of protein) and cytochrome b-245 (479 pmol/mg of protein) and produced 11.61 mol of O2-./s per mol of cytochrome b (340 nmol of O2-./min per mg of protein). On addition of NADPH, the cytochrome b-245 was reduced by 7.9% and the FAD by 38% in the aerobic steady state; NADH addition caused little steady-state reduction of cytochrome b and FAD. In this preparation, and several others, the measured rate of O2-. production correlated with the turnover of cytochrome b calculated from the extent of cytochrome b-245 reduction under aerobic conditions. Addition of diphenyleneiodonium abolished the reduction of both the FAD and cytochrome b-245 components and inhibited O2-. production. The haem ligand imidazole inhibited O2-. generation and cytochrome b reduction while permitting FAD reduction. These results support the suggestion that the human neutrophil NADPH oxidase has the electron-transport sequence: NADPH----FAD----cytochrome b-245----O2.

Cytochrome b Group↗
PubMed1989

Effects of cyclopiazonic acid and aflatoxin singly and in combination on selected clinical, pathological and immunological responses of guinea pigs.

Cyclopiazonic acid (CPA) and aflatoxin are known sometimes to coexist in nature but little is known of possible biological interaction in mammals that consume mixtures of these two mycotoxins. Guinea pigs were dosed orally with CPA (2.2 mg/kg) or aflatoxin (0.045 mg B1/kg) singly or in combination. Effects of toxin consumption were determined on clinical health, body weight gain, pathological change, and several immunologically related parameters including delayed cutaneous hypersensitivity, antibody response, complement hemolytic titer, intracutaneous mitogen (PHA) and in vitro lymphocyte blastogenesis. In contrast to an earlier study by others, significant synergy between these two toxins was demonstrated in reduced rate of body weight gain, lethality and histologic changes (vacuolization) in hepatocytes. Reductions in complement titer, intradermal PHA, delayed cutaneous hypersensitivity response and in vitro lymphocyte blastogenesis were related to aflatin activity. No effects on antibody formation to Brucella abortus were observed with either toxin or the combination of toxins. Cyclopiazonic acid appeared to restore the suppressive effects of aflatoxin in delayed cutaneous hypersensitivity response and in vitro lymphocyte blastogenesis.

Administration, Oral↗
PubMed1989

Acquired resistance to ixodid ticks induced by tick cement antigen.

Antisera from guinea pigs made resistant to infestation with an ixodid tick of east and central Africa, Rhipicephalus appendiculatus, were used to identify the tick antigens they recognized by immunoblotting. Most of the antigens were found in tick salivary glands and in tick attachment cement. Antisera from R. appendiculatus-resistant guinea pigs also recognized some salivary-gland antigens in ticks of other species (R. pulchellus, R. evertsi, Amblyomma variegatum and A. gemma). Antibodies against the most strongly recognized R. appendiculatus antigen, a 20-kDa molecule, were only poorly reactive with similar-sized molecules in the other ticks. A 94-kDa antigen, which appeared to have broader cross-reactivity, was purified from R. appendiculatus attachment cement, and a monospecific rabbit serum was raised against it. This antiserum clearly recognized a molecule of similar molecular weight in R. pulchellus and R. evertsi. Intravenous inoculation of rabbits with the purified molecule elicited delayed-type hypersensitivity to the antigen. The hypersensitive rabbits demonstrated resistance to feeding of R. appendiculatus ticks but slight enhanced feeding of R. pulchellus ticks. These results are discussed with respect to their relevance for artificial induction of tick-feeding resistance.

Animals↗
PubMed1989

Lymphocyte alterations in zinc-deficient calves with lethal trait A46.

Lymphocyte numbers and activities were evaluated at 2, 4, 8 and 12 weeks of age in two calves with lethal trait A46 (A46), a genetic disorder affecting intestinal zinc absorption. Plasma zinc concentrations declined to subnormal by 3 weeks of age, after which anorexia, diarrhea, alopecia and hyperkeratosis occurred. Lymphocyte response to phytohemagglutinin-P (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) stimulation was variably reduced. CD4+ T-lymphocytes were subnormal on at least one observation period following onset of zinc deficiency, and relative numbers of B lymphocytes were decreased at 8 weeks. Secondary antibody responses to bacteriophage phi X 174 were significantly reduced. The results demonstrate that calves homozygous for the A46 trait have normal numbers of functional lymphocyte subpopulations at birth, and that the activity of their lymphocytes is altered once the calves become zinc deficient.

Animals↗
PubMed1988

The effect of the NADPH oxidase inhibitor diphenyleneiodonium on aerobic and anaerobic microbicidal activities of human neutrophils.

NADPH-dependent superoxide production by intact human neutrophils is inhibited by DPI (diphenyleneiodonium), when stimulated by either FMLP (N-formylmethionyl-leucyl-phenylalanine) or PMA (phorbol 12-myristate 13-acetate). Addition of 10 microM-DPI abolished the reduction of both the FAD and the cytochrome b components of the NADPH oxidase. DPI inhibition of the oxidase was associated with defective aerobic killing of staphylococci by human neutrophils. Anaerobic killing, phagocytosis, chemotaxis and motility were relatively unaffected by 10 microM-DPI. Degranulation of the azurophil and specific granules, induced by the soluble stimuli FMLP or PMA, and by particulate stimuli was decreased by the presence of DPI. The above effects of DPI on human neutrophils are similar to those found in chronic granulomatous disease.

Aerobiosis↗
PubMed1988

Differentiation antigens on bovine mononuclear phagocytes identified by monoclonal antibodies.

Five monoclonal antibodies (MAb) produced against cell surface antigens on bovine mononuclear phagocytes (MPh) were characterized. None of the MAb recognized erythrocytes, thrombocytes, B lymphocytes or resting or activated T lymphocytes. Two MAb (IL-A22 and IL-A24) reacted with the majority of monocytes and granulocytes in peripheral blood, with 20-40% bone marrow cells comprising myelo-monocytic cells, and with a proportion of mature macrophages. Reactivity of the remaining three MAb was restricted to MPh: one of these (IL-A25) was apparently specific for pulmonary macrophages, whereas the molecules recognized by the other two (IL-A23 and CH16A) were expressed on subpopulations of blood monocytes and tissue macrophages. None of the MAb inhibited adherence of MPh to plasma-coated gelating surfaces or Fc-mediated rosette formation. One of the MAb, IL-A24, which reacts with MPh and granulocytes, inhibited antigen-specific proliferative response or peripheral blood mononuclear leukocytes (PBM) to the soluble antigen, keyhole limpet hemocyanin (KLH) but did not inhibit responses to concanavalin A or allogeneic leukocytes. This MAb was shown to react with two polypeptides of approximately 75 kD and 110 kD on the surface of peripheral blood monocytes.

Animals↗
PubMed1988

Flow cytofluorimetric analysis of lymphocyte subset alterations in cattle infected with bovine viral diarrhea virus.

Clinically normal, bovine viral diarrhea virus (BVDV)-seronegative, 7 to 9-month-old steers were inoculated intranasally with NY-1, a noncytopathic strain of BVDV, or exposed intramuscularly to killed BVDV. Indirect immunofluorescence staining with monoclonal antibodies specific for bovine leukocyte subsets followed by flow cytometric analysis was used to monitor subsequent hematologic alterations. Infection with BVDV resulted in a transient leukopenia which was characterized by decreases in the absolute numbers of circulating T lymphocytes, including BoT4+ ("helper") and BoT8+ ("cytotoxic/suppressor") subsets, B lymphocytes, and neutrophils. There was no significant variation in numbers of non-T, non-B ("null") lymphocytes or monocytes. Exposure to inactivated BVDV in a combination vaccine did not cause significant alteration in the circulating numbers of any major leukocyte subset; however, significant variation was seen in the BoT4/BoT8 ratios and in the numbers of cells expressing major histocompatibility complex (MHC) class II antigens.

Animals↗