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Biomedical subjects

L G Adams

Publications and source records attributed to L G Adams.

At least 109 records · Page 6Linked to original sources
PubMed1987

Relationship of fetal age at conjunctival exposure of pregnant heifers and Brucella abortus isolation.

Pregnant heifers were exposed by a conjunctival inoculation with 1 X 10(7) colony-forming units of Brucella abortus strain 2308. At parturition, milk and uterine samples from dams plus samples from dead calves were cultured bacteriologically for Brucella. The logistic regression probability of B abortus isolation increased from 0.22 to 0.90, as fetal age at exposure of heifers increased from 60 to 150 gestation days. Strain 2308 was recovered at parturition from 14 (64%) of 22, 17 (71%) of 24, and all 28 (100%) heifers that were at gestation days less than 127, 127 to 157, and greater than 157, respectively, at time of exposure. The number of infected heifers and the number of samples positive for B abortus were significantly increased as fetal age at exposure of heifers increased from gestation days less than 127 to greater than 157 (chi 2 greater than 10, P less than 0.005).

Animals↗
PubMed1987

Assessment of bovine mammary gland macrophage oxidative burst activity in a chemiluminescence assay.

A major bactericidal mechanism of neutrophils and macrophages is the generation of toxic oxygen-free radicals upon phagocytosis of microbes. Studies were conducted to assess the oxidative metabolism of bovine mammary gland macrophages. Bovine mammary gland macrophages were challenge exposed with a variety of phagocytic stimuli in an in vitro, luminol-assisted chemiluminescence assay. A measurable oxidative burst was observed when macrophages were challenge exposed with heat-aggregated bovine immunoglobulin, opsonified zymosan, and nonosponified zymosan. Addition of superoxide dismutase decreased mammary gland macrophage chemiluminescence in a dose-dependent manner. Brucella abortus, when opsonified with antiserum, lacteal antibody, or normal serum, produced an oxidative event, whereas nonopsonified B abortus did not. When challenge exposed with phagocytic stimuli, mammary gland macrophages produced an oxidative burst similar to that produced by other phagocytes for which an oxidative event is known to be bactericidal.

Animals↗
PubMed1985

The role of lysosomes in the pathogenesis of copper-induced hepatotoxicity: morphological studies.

Copper-induced hepatotoxicity was evaluated in beige and conventional mice which were injected intraperitoneally with aqueous copper chloride (8 mg per kg body weight per day). Hepatic lesions developed more quickly and were more severe in beige mice and consisted of karyomegaly, progressive accumulation of lipofuscin within hepatocytes and Kupffer cells, acute necrosis of random hepatocytes, and aggregation of leukocytes within the sinusoids. In both groups of mice the hepatic lesion had a centrilobular distribution and closely paralleled the appearance and distribution of copper within hepatocytes. Overall, beige mice had more severe copper-mediated hepatotoxicity, suggesting that normal lysosomes have protective effects for hepatocytes by sequestering copper from other cytoplasmic constituents.

Animals↗
PubMed1985

Immune responsiveness and lymphoreticular morphology in cattle fed hypo- and hyperalimentative diets.

Immune responses and lymphoreticular morphology were studied in 3 groups of yearling Hereford steers fed hypoalimentative, maintenance and hyperalimentative diets for 142 days. Significant decreases in plasma protein levels and circulating lymphocyte levels occurred in low energy intake steers. Percent circulating lymphocytes bearing surface immunoglobulins and serum levels of IgG and IgM did not vary significantly within or between groups. Antibody responses to Brucella abortus bacterin inoculated on day 63 were similar in all 3 groups. Antibody responses to chicken erythrocytes inoculated on day 88 were significantly lower in hypoalimentated steers. Differences between groups in lymphocyte blastogenic responses to phytohemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) were not significant. Hyperalimentated steers had significantly depressed PWM responses compared to a baseline value established for that group. In addition, hypoalimentated steers tended to have elevated responses to PHA, although differences were not significant. There were no significant differences between groups in dermal hypersensitivity responses to tuberculin following sensitization with viable Bacillus Calmette-Guerin (BCG). The thymuses of hypoalimentated steers were markedly atrophied but lymph nodes and splenic white pulp were normal. Thymus, lymph nodes and spleen were normal in hyperalimentated steers.

Animals↗
PubMed1984

Immunochemical studies on the binding properties of Brucella abortus lipopolysaccharides to bovine precipitating antibodies.

The binding properties of Brucella abortus smooth lipopolysaccharides (LPS) to the precipitating antibodies in the serum of a B. abortus S2308 infected cow were studied by quantitative precipitin and precipitin-inhibition assays. Crude B. abortus lipopolysaccharides (cLPS) and chemical modification products of strains 1119.3, 19 and 2308 (virulent) were used for this study. In the quantitative precipitin assay, 13 micrograms of cLPS precipitated about 4.0-5.2 micrograms nitrogen of precipitating antibodies in 10 microliter of serum. After alkaline treatment (0.125 N NaOH at 56 degrees C for 1 hr), the alkali-treated lipopolysaccharides (aLPS) from S19 and S1119.3 maintained the maximum precipitability, but the precipitation profile was changed from a sigmoidal to a bell-shaped curve, and aLPS from S2308 was reduced to about 40% of its reactivity. These results indicate that some of the antigenic determinants blocked by other molecules were reshielded by alkaline treatment, and possibly that structural differences exist between virulent (S2308) and nonvirulent (S19 and S1119.3) strains. Among the monosaccharides and glycosides tested for inhibition of precipitation, methyl alpha-D-mannose was most active and about 3.3 times as active as D-mannopyranose (DMan) and only 1/200 as active as acid hapten or the carbohydrate moiety of cLPS prepared from S1119.3 (expressed as a monosaccharide of mol. wt 200) implying that the carbohydrate determinants of this antigen are probably related to a DMan alpha 1----linked compound. The precipitability of the antibodies in this serum was greatly reduced after absorption with cLPS and the precipitin reaction was completely inhibited by the carbohydrate moiety of LPS (O-antigen) S1119.3 demonstrating that the common antigenic determinants (hapten) of B. abortus LPS reacting with these precipitating antibodies are in the region of the carbohydrate moiety of the LPS.

Animals↗
PubMed1984

Experimental infection of captive axis deer with Brucella abortus.

Four captive-raised axis deer, Axis axis (Erxleben), which were negative serologically to Brucella were inoculated with 1 X 10(8) virulent Brucella abortus biotype 1 organisms (Texas #221 isolate) administered bilaterally into the conjunctival sac. Sera collected from each deer prior to inoculation and 30 days post-inoculation (PI) were examined for Brucella antibodies by the buffered Brucella antigen (card), the rivanol precipitation, the standard tube agglutination, and the cold complement fixation tube serologic tests. All four axis deer converted serologically as determined by all tests at 30 days PI. Brucella abortus biotype 1 was isolated from 26 of 32 tissue samples collected at necropsy and also from milk from the lactating female.

Agglutination Tests↗
PubMed1983

The role of lysosomes in the pathogenesis of copper-induced hepatotoxicity. II. Intracellular distribution of copper in hepatocytes.

The effects of altered lysosomal function on the pathogenesis of copper-induced hepatotoxicity were studied in C57B1/6 bg/bg (beige) and C57B1/6 bg/+ (conventional) mice. Copper loading was accomplished through daily ip injections of aqueous copper chloride at a dosage rate of 8 mg/kg body weight for 1, 2, and 4 weeks. The subcellular distribution of copper in copper-treated beige mice was significantly different than that in conventional mice. Beige mice had consistently higher levels of copper in the nuclear and cytosolic fractions with lower levels in the heavy and light mitochondrial fractions. The copper levels were lowest in the microsomal fractions of both groups of copper-treated mice and remained similar throughout the 4-week experiment. Levels of total hepatic copper were similar in both groups of mice receiving parenteral copper except at Day 14, when beige mice had higher levels.

Animals↗
PubMed1983

Derivation of monoclonal antibodies against Brucella abortus antigens.

In vivo immunization, fusion, antibody detection, and cryopreservation procedures for monoclonal antibody production against antigens of Brucella abortus are described. Splenocytes from BALB/c mice immunized with irradiated B. abortus S2308 were fused with Sp2/O-Ag14 myeloma cells and 61 hybridomas secreting anti-Brucella antibodies were cloned. Hybridoma antibody synthesis was detected effectively and most efficiently by enzyme-linked immunosorbent assays. Antibodies from clones of hybridoma A23 reacted with S19 and S2308 whole bacterial cells, while hybridoma B49 reacted primarily with alkali--treated lipopolysaccharides of S19, S1119.3 and S2308. Cryopreservation of clones had no major effect on antibody synthesis. The application of monoclonal anti-Brucella antibodies in the differential diagnosis of bovine brucellosis is discussed.

Animals↗
PubMed1983

Failure of bovine complement levels measured by radial hemolysis to correlate with tube titration.

Hemolytic complement levels in 30 duplicate samples of normal bovine sera were determined by a tube titration method (CH50) and by a radial hemolysis in gel assay. Significant correlation was not observed between the values obtained by the 2 tests. This lack of correlation could be a result of considerable error observed in values obtained for duplicate samples in the CH50 method or to the relative insensitivity of the hemolysis in gel test. The hemolytic reaction in gel was found to depend on Mg2+, thus raising questions (i) about its validity in determining total hemolytic complement or (ii) about bovine C1q depending on Mg2+ rather than Ca2+ for binding to immune complexes.

Animals↗
PubMed1982

Hemoparasitism, humoral immunodeficiency, and an IgG1 fragment in a cow.

An adult cow with nonregenerative anemia was found to be infected with Eperythrozoon wenyoni and Trypanosoma theileri. Further laboratory testing revealed hypoalbuminemia, hypogammaglobulinemia, decreased numbers of circulating B lymphocytes, and presence of a serum immunoglobulin G1 fragment. Reduced B-lymphocyte regions in lymphoid tissue, evidence of chronic nephritis, and infection with Fasciola hepatica and Sarcocystis spp were found at necropsy. The cause of the acquired humoral immunodeficiency and the serum immunoglobulin G1 fragment was undetermined.

Anaplasmataceae Infections↗
PubMed1982

Humoral and cell-mediated immune responses in chickens with infectious bursal disease.

Primary and secondary immune responses to Newcastle disease virus (NDV) was evaluated in chickens infected with infectious bursal disease virus (IBDV) at one and 28 days of age. The geometric mean primary hemagglutination-inhibition antibody titers (GMT) of chickens infected with IBDV at one day of age was significantly lower (P less than or equal to 0.01) than those infected at 28 days of age. Infection with IBDV had no influence on secondary immune response to NDV. The effect of IBDV infection at one day of age on the cell-mediated immunity of chickens was evaluated by skin allograft acceptance or survival time. There was no significant difference between the percentage of grafts accepted in IBDV infected and noninfected control chickens. However, the mean graft survival time in the IBDV infected chickens was significantly longer (P less than or equal to 0.05) than those in the control group. This suggested a suppression of cell-mediated immunity due to IBDV infection.

Animals↗
PubMed1982

Response to neonatally thymectomized Holstein calves to bacille Calmette Guérin.

Neonatally thymectomized and intact Holstein calves were inoculated intradermally with bacille Calmette Guérin mycobacteria at 4 to 6 months of age. The immune response of the calves was evaluated by in vitro lymphocyte stimulation, with a purified protein derivative of Mycobacterium bovis, and by a cervical skin test. Eight of te calves had been previously infected at 7 to 15 weeks of age with bovine viral diarrhea virus. The cutaneous and in vitro immune responses were not different in neonatally thymectomized calves, whether or not they had been previously infected with bovine viral diarrhea virus. However, a prominent histologic difference in the nature of the primary granulomatous lesions was observed in the thymectomized calves. These injection sites were characterized by few lymphocytes and an increased number of multinucleated giant cells. These observations were interpreted as manifestations of a deficient thymus-dependent effector response in the thymectomized calves.

Animals↗
PubMed1981

Effect of neonatal thymectomy and antilymphocyte globulin on non-specific mitogen stimulation in Holstein-Friesian calves.

Nine of seventeen neonatal Holstein-Friesian calves were thymectomized, treated with antilymphocyte globulin, and monitored for immunologic functional ability for 4 to 6 months. The thymus weights for 4 to 10-day-old calves and 4 to 6-month-old calves indicated a continued increase in total weight. This indicated significant thymic involution had not occurred at 4 to 6 months. Following thymectomy a wasting syndrome was not observed although an increased incidence of a lowly virulent virus infection did occur. A significant decrease in circulating lymphocytes was observed. Peripheral blood lymphocytes were stimulated in vitro by non-specific mitogens, phytohemagglutinin, bacterial lipopolysaccharide and pokeweed mitogen using the whole blood culture method. Observations included a greater response to phytohemagglutinin and pokeweed mitogen in summer months and variable age related response to all mitogens. Lipopolysaccharide stimulation results were inconclusive. It was concluded that neonatal thymectomy was not a satisfactory experimental procedure for the production of selective immunosuppression in the bovine species.

Animals↗
PubMed1981

Recrudescence of Anaplasma marginale induced by immunosuppression with cyclophosphamide.

Eight doses of cyclophosphamide (5 mg/kg), at 2-day intervals between doses, were administered IV to Anaplasma-carrier splenectomized calves. Significant decreases in serum immunoglobulins, diminished complement-fixing antibody response, and transitory leukopenia were associated with the treatment. Recrudescence of clinical Anaplasma infection occurred after the 5th dose of cyclophosphate was given and was characterized by rapid increase in parasitemia, marked decrease in PCV, and mortality. The results of the present study indicated that humoral mediated immunity may contribute to the maintenance of a state of equilibrium in the host-parasite relationship and that suppression of humoral immune responses may alter the course and outcome of infection in Anaplasma carriers.

Anaplasmosis↗
PubMed1981

Clinicopathological aspects of imidocarb dipropionate toxicity in horses.

Six groups of four adult horses were twice injected intramuscularly at a 24 hour interval with 0, 2, 4, 8, 16 or 32 mg/kg of imidocarb dipropionate (IMDP) and monitored for 21 days. The LD50 of IMDP for 21 days after injection was two doses of 15.99 +/- 1.49 mg/kg with mortalities occurring within six days following the first injection. Increasing levels of IMDP were correlated with increasing rates of morbidity, mortality, local and systemic reactions, increasing levels of blood urea nitrogen, serum aspartate amino transferase, serum sorbitol dehydrogenase, serum creatine phosphokinase, neutrophilia and increasing severity of renal, hepatic and pulmonary lesions. Mortalities were attributed to acute renal cortical tubular necrosis and acute periportal hepatic necrosis induced by two injections of 16 or 32 mg/kg of IMDP.

Abortion, Veterinary↗