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Biomedical subjects

T T Brown

Publications and source records attributed to T T Brown.

At least 37 records · Page 2Linked to original sources
PubMed1996

Mucinous adenocarcinoma in the abomasum of a cow.

A cow with mucinous adenocarcinoma of the abomasum presented to the teaching hospital with a markedly distended abdomen from which 80 liters of fluid was drained during trocharization. An exploratory laparotomy allowed removal of an additional 80 liters of fluid from the peritoneal cavity and revealed a diffusely thickened parietal peritoneum and a palpable cranial abdominal mass. The cow was euthanatized. At necropsy, the abomasum was diffusely thickened and firm. The peritoneal and pleural surfaces were covered with numerous coalescing, firm white nodules. Microscopically, the thickened abomasum was multifocally effaced by aggregates, cords, and acini of neoplastic cells separated by amphophilic, foamy to wispy periodic acid-Schiff- and alcian blue-positive material. Cell boundaries were indistinct and large, clear, colorless intracytoplasmic vacuoles were common.

Abomasum↗
PubMed1996

Immune response and disease resistance of calves fed chromium nicotinic acid complex or chromium chloride.

Twenty-one Holstein bull calves (< 7 d of age at the initiation of the experiment) fed a milk replacer diet were used to assess the effects of supplemental Cr on immune response. Treatments consisted of milk replacer without supplemental Cr (control) or milk replacer with 0.4 ppm of supplemental Cr from CrCl3 or a Cr-nicotinic acid complex. On d 64, increases in skinfold thickness after an intradermal injection of phytohemagglutinin were measured to evaluate cell-mediated immune response. Calves supplemented with Cr-nicotinic acid complex had a greater response than did controls at 6, 12, 24, and 48 h after injection. Calves supplemented with CrCl3 had a greater response than did controls at 24 and 48 h after injection. In vitro blastogenic responses of lymphocytes to phytohemagglutinin or pokeweed mitogen and antibody response to porcine red blood cells were not affected by treatment. Following a disease challenge with an intranasal dose of infectious bovine rhinotracheitis on d 75, body temperature tended to be lower for calves supplemented with Cr-nicotinic acid complex than for control calves. Calves supplemented with either Cr source had lower serum cortisol concentrations at 5 d after challenge. Chromium supplementation enhanced cell-mediated immune function.

Animals↗
PubMed1995

Detection of pseudorabies viral DNA in tonsillar epithelial cells of latently infected pigs.

The Rice strain of pseudorabies virus (PRV) was intranasally instilled in pigs that were seronegative to PRV. Cells were scraped or brushed from tonsillar surfaces biweekly until pigs were euthanatized at either 10 or 16 weeks after infection. The DNA extracted from tonsillar cells or parenchyma were subjected to polymerase chain reaction analysis, using either a single set of oligonucleotide primers or nested primers from the PRV gII glycoprotein gene. Pigs became seropositive to PRV by 3 weeks after infection. The virus was isolated from the trigeminal ganglia and tonsils of pigs that were euthanatized or died 1 to 2 weeks after infection, but not from pigs that were euthanatized 10 or 16 weeks after infection. The PRV gene products were consistently detected in trigeminal ganglia and tonsils of all pigs at 1, 10, and 16 weeks after infection, and sporadically in the nasal mucosa, lymph nodes, and lungs of pigs that were euthanatized or died during the first 2 weeks after infection. Cells collected biweekly from tonsillar surfaces were mostly nucleated, squamous epithelial cells with fewer lymphocytes and neutrophils. Polymerase chain reaction analysis of DNA extracted from these cells revealed PRV DNA in a large proportion of the samples when sufficient cells were collected to provide 1 microgram of extracted DNA for use in the reaction mixtures. A second group of pigs had PRV strain 4892 intranasally instilled. The virus was isolated from tonsillar swab specimens until 3 weeks after infection. Tonsillar brushing specimens were collected biweekly until 14 weeks after infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Effect of copper deficiency on tissue, blood characteristics, and immune function of calves challenged with infectious bovine rhinotracheitis virus and Pasteurella hemolytica.

Fourteen Holstein steers, averaging 30 d of age, were fed a semipurified diet (1.5 mg of Cu/kg) supplemented with 0 (-Cu) or 10 mg of Cu/kg of diet (+Cu) for 5 mo. Calves were then challenged by consecutive exposure to aerosol preparations of infectious bovine rhinotracheitis virus (IBRV) and Pasteurella hemolytica on d 0 and 7, respectively, of the 30-d study. Serum ceruloplasmin and plasma copper were higher in +Cu calves throughout the challenge period and increased in +Cu calves after microbial challenge. Heart weights were higher in -Cu calves, although weights of liver, spleen, and thymus were not different between treatments. Copper concentrations in all tissues as well as thymus zinc were higher in +Cu calves. Serum immunoglobulin M tended to be higher in +Cu calves and increased in both treatments after IBRV challenge. Serum IBRV antibody titers were higher in -Cu calves with detectable seroconversion by d 10 postinfection. In contrast, antigen-specific antibodies to P. hemolytica tended to be higher in +Cu calves on d 21. Copper status did not affect blastogenic response, but phytohemagglutinin (PHA)-stimulated blastogenesis was higher in both treatments after IBRV challenge. Repletion of lymphocyte cultures with copper chloride increased proliferative responses to PHA in both +Cu and -Cu calves, and greater responses at all levels of copper (1 to 16 micrograms/mL) were noted in -Cu calves. These results indicate that copper deficiency affects various physiological characteristics that may be important in immunological defense to pathogenic challenge.

Animals↗
PubMed1991

Effects of zinc methionine and zinc oxide on performance, blood characteristics, and antibody titer response to viral vaccination in stressed feeder calves.

Ninety steers with an average weight of 214 kg were purchased at 2 feeder calf sales and transported 70 to 100 km. On arrival at the feedlot, steers were weighed and identified, blood was withdrawn, and the steers were vaccinated against bovine herpesvirus-1 (BHV-1) and parainfluenza3 (PI3), using a modified live vaccine, and randomly assigned to treatment groups. Treatments were: control (no supplemental zinc; zinc methionine; and zinc oxide. The control diet contained 26 mg of zinc/kg diet, and zinc was added in treatments 2 and 3 to provide 25 mg of supplemental zinc/kg diet. Neutralizing antibody titers were determined on serum samples taken on days 0 and 14 as a measure of the immune response to BHV-1 and PI3 vaccination. Weight gains for the 28-day study were similar across treatments. Dry matter intake tended to be higher in steers fed supplemental zinc from either source, because steers fed zinc methionine and zinc oxide consumed 5.2 and 4.4% more feed, respectively, than controls. Antibody titers against BHV-1 tended to be higher in steers supplemented with zinc methionine on day 14. Differences between treatments were not found for PI3 titers. Mortalities did not occur and morbidity rate was low.

Animals↗
PubMed1991

Changes in phospholipids of alveolar lining material in calves after aerosol exposure to bovine herpesvirus-1 or parainfluenza-3 virus.

Pulmonary lavage samples were collected from 90- to 130-day-old calves before and 6 days after aerosol inoculation with bovine herpesvirus-1 (BHV-1) or parainfluenza-3 (PI3) virus. Alveolar lining material was separated from lavage fluids by high-speed centrifugation and phospholipids were extracted from alveolar lining material and analyzed by high-performance liquid chromatography. Phosphatidylcholine and phosphatidylethanolamine were 74.2 +/- 6.5% and 13.3 +/- 2.8%, respectively, of the total phospholipid content in the surfactant obtained from calves before virus inoculation. Other phospholipids were represented by substantially lower percentages. Infection with either of the 2 viruses caused a significant (P less than or equal to 0.05) decrease in the percentage of phosphatidylcholine to 66.0 +/- 8.0% and 65.1 +/- 10.8% in the calves inoculated with BHV-1 and PI3 virus, respectively. A significant (P less than or equal to 0.05) increase in the percentage of phosphatidylethanolamine to 18.1 +/- 2.2% and 17.8 +/- 4.5% developed in calves inoculated with BHV-1 and PI3 virus, respectively. Infection with BHV-1 also induced an increase (not significant) in the percentage of phosphatidylinositol from 5.5 +/- 2.8% to 7.8 +/- 2.2%. A similar, but not significant, increase in the percentage of phosphatidylinositol was also seen in the calves inoculated with PI3 virus. Less substantial changes in the percentage of other phospholipids were detected after virus infection.

Aerosols↗
PubMed1990

Effect of bovine herpesvirus-1 or parainfluenza-3 virus on immune receptor-mediated functions of bovine alveolar macrophages in the presence or absence of virus-specific serum or pulmonary lavage fluids collected after virus infection.

The immune receptor-mediated functions of bovine alveolar macrophages (AM) inoculated in vitro with bovine herpesvirus-1 (BHV-1) or parainfluenza-3 (PI-3) virus were tested in the presence or absence of virus-specific antiserum or pulmonary lavage fluids collected from calves 6 days after inoculation with BHV-1 or PI-3 virus. The Fc and C3b phagocytic indices of noninoculated AM, collected from 6- to 16-week-old calves, ranged from 75 to 87 and 59 to 64, respectively, and the binding indices ranged from 5 to 8 and 22 to 28, respectively. Infection of AM with either BHV-1 or PI-3 virus had no significant effect on receptor-mediated phagocytosis or binding, with the exception of a significant (P less than 0.05) decrease, from 64 to 46, of the C3b phagocytic index of PI-3 virus-infected AM. The addition of lavage fluids, collected after BHV-1 or PI-3 virus infection, to AM infected with the respective virus caused a significant (P less than 0.05) decrease in phagocytic indices with values for the Fc and C3b indices in BHV-1-infected AM decreasing from 81 to 49 and from 47 to 8, respectively, and those for the PI-3 virus-infected AM from 79 to 51 and from 46 to 15, respectively. The binding indices of virus-infected AM increased with the addition of viral lavage fluids, but the only significant (P less than 0.05) increase was for C3b binding in PI-3 virus-infected cells, which increased from 33 to 56.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Modulation of arachidonic acid metabolism by bovine alveolar macrophages exposed to interferons and lipopolysaccharide.

Stimulation of bovine alveolar macrophages with calcium ionophore A23187 resulted in marked production of leukotriene (LT)B4 and a lesser increase in thromboxane (TX)B2, whereas opsonized zymosan (OPZ) resulted in production of TXB2 and relatively small increases in LTB4 and prostaglandin (PG)F2 alpha. Alveolar macrophages incubated with recombinant bovine interferon-gamma or lipopolysaccharide, and subsequently stimulated with A23187 or OPZ, had altered arachidonic acid metabolism, producing markedly increased amounts of TXB2 and PGF2 alpha, and slightly increased LTB4. Incubation of alveolar macrophages with lipopolysaccharide had a more profound effect on the increased amounts of TXB2 and PGF2 alpha, observed in response to stimulation with A23187 or OPZ, than did incubation with interferon-gamma. Alveolar macrophages incubated with recombinant bovine interferon-alpha 1-1 also produced slightly increased amounts of LTB4 when stimulated with A23187 or OPZ. Altered arachidonic acid metabolism by alveolar macrophages exposed to interferons and lipopolysaccharide may contribute to the development of pulmonary inflammation, such as in the early stages of bacterial pneumonia following viral infections that induce interferon production.

Animals↗
PubMed1989

Selenium effects on glutathione peroxidase and the immune response of stressed calves challenged with Pasteurella hemolytica.

The present study was conducted to determine whether a marginal Se deficiency affects health, blood characteristics and the immune response of calves subjected to stresses associated with weaning, shipping (332 km) and Pasteurella hemolytica inoculation. Treatments were 1) -Se, 2) -Se/P. hemolytica, 3) +Se (.1 mg Se/kg feed) and 4) +Se/P. hemolytica. Previous Se intake was controlled; dams of -Se calves were fed diets marginally deficient in Se (.03 to .05 mg/kg), whereas dams of +Se calves received a s.c. injection of 30 mg Se (as sodium selenite) every 60 d. Calves were inoculated with P. hemolytica intratracheally on d 3 following weaning and transport. Inoculation with P. hemolytica increased (P less than .05) body temperatures, platelet counts, serum IgM concentrations and serum antibody titers and decreased serum albumin concentrations at 4 to 7 d postinoculation. Weight gains for the 21-d study were not affected by Se status, although whole blood and plasma glutathione peroxidase (GSH-Px) were higher (P less than .05) for +Se calves. Plasma GSH-Px increased (P less than .01) in calves showing signs of morbidity. Increases in plasma GSH-Px were correlated positively with body temperature. Serum IgM concentrations were higher (P less than .05) in +Se calves on d 17, but Se-supplemented calves had lower (P less than .05) anti-P. hemolytica titers on d 17 than -Se calves. Selenium status did not affect body temperatures, plasma creatine phosphokinase or serum IgG and albumin concentrations. These results indicate that Se status can affect IgM concentrations following stress.

Animals↗
PubMed1988

Effect of dietary selenium on the primary and secondary immune response in calves challenged with infectious bovine rhinotracheitis virus.

The present study was conducted to determine if a selenium deficiency affects the primary and secondary humoral immune response of calves challenged with infectious bovine rhinotracheitis virus (IBRV) and to evaluate changes in glutathione peroxidase (GSH-Px) and creatine phosphokinase activities associated with selenium deficiency and viral stress. Treatments included 1) +Se (0.2 mg/kg diet) and 2) -Se (0.03 mg/kg diet). Calves were adapted to their assigned diets during an 84-d depletion period. By d 42 of the depletion period, whole-blood GSH-Px was lower for -Se calves than for +Se calves. Differences between treatments in plasma GSH-Px were observed by d 14. On d 84, Se-dependent GSH-Px activity in liver was higher in +Se calves. After depletion of -Se calves, animals in both treatments were intranasally inoculated with IBRV on d 0 and 35 of the 70-d challenge phase. Whole-blood and plasma GSH-Px increased after IBRV inoculation in +Se calves but not in Se-deficient calves. Serum IgM was higher for +Se calves throughout the challenge phase. Serum IgM increased in both treatments after primary IBRV inoculation but was unaffected by secondary challenge. Serum IgG was not affected by selenium status but increased in both treatments after secondary IBRV challenge. Serum IBRV antibody titers increased after inoculation on d 0 and 35. By d 49, IBRV antibody titers were higher for +Se calves than in Se-deficient calves. These results indicate that selenium deficiency may depress the immune response of calves challenged with a foreign pathogen.

Animals↗
PubMed1988

Effect of dietary selenium and vitamin E on the primary and secondary immune response in lambs challenged with parainfluenza3 virus.

This study was conducted to determine the effect of dietary selenium (Se) and vitamin E (Vit E) on various blood characteristics and the primary and secondary humoral immune response of lambs challenged with parainfluenza3 virus (PI3 V). Treatments included: 1) +Se/+Vit E, 2) -Se/+Vit E, 3) +Se/-Vit E and 4) -Se/-Vit E. The basal diet (-Se/-Vit E) was deficient in Se and Vit E. Sodium selenite (.2 mg Se/kg diet) and alpha-tocopherol acetate (20 mg Vit E/kg diet) were added to +Se and +Vit E diets, respectively, to provide adequate levels of each according to NRC recommendations. Following a 10-wk dietary adaptation and depletion period, lambs in all treatment groups were intratracheally inoculated with PI3 V on d 0 and 35 of the 70-d study. Prior to inoculation, whole blood and plasma glutathione peroxidase (GSH-Px) activities were higher (P less than .01) for +Se lambs. Whole blood and plasma GSH-Px increased (P less than .01) after primary viral inoculation in +Se lambs but not in -Se lambs. Serum immunoglobulin M (IgM) concentrations were enhanced (P less than .05) by Se supplementation on d 14, 35 and 49 of the study. Selenium and (or) Vit E did not affect serum immunoglobulin G (IgG) levels. Serum PI3 V antibody titers increased after inoculation on d 0 and 35 in all treatment groups. Titer levels appeared to increase more substantially for +Se lambs after primary inoculation, but increases were greater (P less than .01) for +Vit E lambs after secondary challenge.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Arachidonic acid metabolites produced by bovine alveolar macrophages.

Bovine alveolar macrophages, obtained by bronchoalveolar lavage, were labeled with tritiated arachidonic acid. The cells were stimulated with calcium ionophore A23187, and the radiolabeled arachidonic acid metabolites that were released were identified by reverse-phase high-performance liquid chromatography. Leukotriene B4 and 5-hydroxyeicosatetraenoic acid were consistently observed. The lipoxygenase inhibitor, nordihydroguaiaretic acid, blocked production of these metabolites. The cyclooxygenase products, prostaglandin F2 alpha and thromboxane B2, were observed infrequently in comparison with leukotriene B4 and 5-hydroxyeicosatetraenoic acid.

Animals↗
PubMed1988

Effect of respiratory infections caused by bovine herpesvirus-1 or parainfluenza-3 virus on bovine alveolar macrophage functions.

Calves, 90 to 130 days old, were inoculated with bovine herpesvirus-1 (BHV-1) or parainfluenza-3 (PI-3) virus. Pulmonary lavage specimens obtained from calves before virus inoculation contained 98% alveolar macrophages (AM) and 1% neutrophils. Six days after inoculation, the mean percentage of neutrophils in lavage specimens had significantly increased to 7.9 +/- 6.0% in BHV-1-inoculated calves and to 18.3 +/- 9.9% in PI-3 virus-inoculated calves, reflecting viral-induced pulmonary inflammation that was confirmed histologically. Approximately 75% of AM obtained before virus inoculation had Fc surface receptors, and 60% had C3b receptors. Six days after inoculation, the percentage of AM with Fc and C3b receptors was significantly reduced to 69.7 +/- 8.6% and 27.1 +/- 19.8%, respectively, in BHV-1-inoculated calves and to 67.8 +/- 15.4% and 38.8 +/- 23.2%, respectively, in PI-3 virus-inoculated calves. Alveolar macrophages obtained after virus inoculation were significantly impaired in their ability to phagocytize opsonized Staphylococcus epidermidis, but were able to kill ingested bacteria. Alveolar macrophage dysfunctions caused by BHV-1 or PI-3 respiratory infection did not differ appreciably.

Animals↗
PubMed1987

Use of an inactivated vaccine for prevention of parvovirus-induced reproductive failure in gilts.

Gilts from dams that had been inoculated with inactivated porcine parvovirus (PPV) vaccine before breeding became seronegative to PPV by 26 weeks of age. Vaccination of these gilts with inactivated PPV vaccine at 32 weeks of age resulted in an antibody response that peaked at about 2 weeks after vaccination, with -log10 mean hemagglutination inhibiting (HI) antibody titers of less than 2. In the first-year group (82 gilts), HI titers gradually decreased, 20% of the gilts being seronegative by 6 to 7 weeks after vaccination and 75% being seronegative by 16 weeks after vaccination. In the second-year group, 93 gilts were infected naturally by a field strain of PPV at about 11 weeks after single vaccination with inactivated PPV. Additionally, in the second year, 20 vaccinated and 6 nonvaccinated gilts were immune-challenged with virulent PPV at 10 to 12 weeks after vaccination. Neither field nor challenge PPV infection of vaccinated pregnant gilts caused reproductive failure, even though some of the gilts became seronegative for PPV before challenge. Our findings suggest that single vaccination of gilts with inactivated PPV vaccine should give adequate protection from PPV-induced reproductive failure, even though serum HI titers decrease to an undetectable level shortly before PPV infection.

Animals↗
PubMed1987

Rhinitis, pneumonia, and defective neutrophil function in the Doberman pinscher.

Eight closely related Doberman Pinschers with chronic rhinitis and pneumonia had normal or increased numbers of structurally normal leukocytes. Serum concentrations of immunoglobulins and complement were above or within normal ranges. Lymphocyte transformation indices for 3 mitogens were normal in 7 of the 8 dogs; the remaining dog had low values for all mitogens. Neutrophils phagocytized bacteria normally, but had impaired bactericidal ability. The bactericidal defect may have been related to the inability of neutrophils to generate normal numbers of oxygen radicals after stimulation, as determined by decreased ability of neutrophils to reduce nitroblue tetrazolium and to produce superoxide following opsonized zymosan stimulation. These observations, plus finding chronic inflammatory disease in the lungs of one dog, indicated that the disease may have some similarity to chronic granulomatous disease or to complement receptor deficiency in man.

Animals↗
PubMed1986

Dexamethasone-induced attenuation of cardiopulmonary dysfunction in endotoxemic calves.

Effects of dexamethasone on pulmonary hemodynamics, pulmonary mechanics, and gas exchange were determined in anesthetized (pentobarbital sodium) and paralyzed (pancuronium bromide) calves (9.4 +/- 0.4 weeks old) during 5 hours of endotoxemia. Escherichia coli endotoxin (055-B5) was infused IV at 20 micrograms/kg the 1st hour, followed by a continuous infusion at 10 micrograms/kg/hour for the following 4 hours. Dexamethasone (5 mg/kg) was given IV 18 hours and 1 hour before endotoxin administration, and was also administered IV (1 mg/kg/hr) during endotoxemia. Endotoxin induced large increases in pulmonary artery pressure, pulmonary vascular resistance, alveolar-arterial O2 gradient, alveolar dead-space ventilation, postmortem gravimetric lung weight of bloodless lung, albumin and total protein concentrations in bronchoalveolar lavage fluid, and the number of neutrophils recovered from bronchoalveolar lavage fluid. Endotoxin induced decreases in the cardiac index, dynamic lung compliance, and PaO2. Dexamethasone attenuated most of the cardiopulmonary responses induced by endotoxin, especially during the first 3 hours of endotoxemia. Dexamethasone blocked endotoxin-induced increases in bronchoalveolar lavage albumin, total protein, and neutrophil content. Therefore, glucocorticoids modify endotoxin-induced pulmonary injury in calves, possibly by limiting mobilization of endogenous arachidonic acid.

Analysis of Variance↗
PubMed1985

Dose-response studies of gentamicin nephrotoxicity in rats with experimental renal dysfunction. I. Subtotal surgical nephrectomy.

Gentamicin pharmacokinetics and nephrotoxicity have not been widely studied in animals with preexisting renal dysfunction, despite the fact that nephrotoxicity is a continuing manifestation of clinical therapy. The present study contrasted the dose-response nephrotoxicity of gentamicin in control rats with that of rats with renal insufficiency secondary to subtotal (2/3) surgical nephrectomy. Total daily doses ranging from 0 to 120 mg/kg were given in a divided regimen, every 8 hr and doses were reduced by doubling the interval in subtotally nephrectomized (Nx) rats, in proportion to impaired renal elimination on the first day of gentamicin administration. Estimates of renal function, including creatinine clearance, fractional sodium and potassium excretion, and serum creatinine and urea nitrogen, were collected after 6 and 12 days of dosing. In addition, urinary N-acetyl-beta-D-glucosaminidase excretion (6 days), in vitro renal cortical slice accumulation of tetraethylammonium (TEA) (6 days), quantified morphological lesions (12 days), and renal gentamicin concentrations (6 days) were examined. Pharmacokinetic data collected immediately after the first dose revealed a reduced gentamicin clearance and slightly reduced volume of distribution, with a corresponding prolonged half-life in the Nx rats. Based on statistical analysis of the dose-response relationships, Nx rats were functionally resistant to gentamicin nephrotoxicity after 6 days of dosing. This resistance was partially reversed by 12 days dosing, despite light-microscopic evidence of greater structural damage in the control rats. Renal parenchymal gentamicin concentrations were lower at some doses in the Nx rats, in contrast to the higher fractional reabsorption found in these rats at all doses. TEA transport was depressed at all doses in control rats but not at the lower doses in Nx rats, indicating that resistance was partially mediated at the level of the proximal tubular epithelium. This study demonstrates altered gentamicin pharmacokinetics and nephrotoxicity in a surgical model of renal dysfunction in rats.

Absorption↗