Requirement for MHC class II positive accessory cells in an antigen specific bovine T cell response

Purified populations of bovine antigen presenting cells (APCs) and T cells have been isolated from peripheral blood and characterised using various monoclonal antibodies (mAbs) for cell surface markers. Bovine APCs were found in an adherent cell fraction and were non-specific esterase positive, phagocytic and expressed bovine major histocompatibility complex (MHC) class II determinants, all of which are typical macrophage characteristics. T cells were rigorously depleted of accessory cell function before being used in an antigen presenting cell assay. The generation of T helper cells in response to the soluble antigen, ovalbumin, was entirely dependent upon a critical number of APCs. Further the proliferative response was inhibited by several mAbs to bovine MHC class II molecules. Thus the interaction between bovine APCs and helper/inducer T lymphocytes (TH/I) appears to be similar to that in other species.     

Antitumor effect of adriamycin entrapped in liposomes conjugated with anti-bovine tumor antigen monoclonal antibody in leukemic cows

Monoclonal antibody c143 against tumor-associated antigen (TAA) expressed on bovine leukemia cells was conjugated to liposomes containing adriamycin (ADM), and therapeutic effects of conjugates were examined in leukemic or preleukemic cows to prevent the progression of the disease. Five cows with TAA-positive in their peripheral blood lymphocytes were divided into two groups. Each group of cows received 4 injections of ADM alone (0.4 mg/kg) or c143-conjugated liposomes containing the same dose of ADM (L-AMD-c143) through the jugular vein at about 4 day intervals. In three animals treated with L-ADM-c143, the TAA-positive cells gradually decreased with treatment and finally two animals became TAA-negative during a 6 week period and a 14 week period after treatment, respectively. In the control, two animals treated with ADM alone showed only a slight decrease of TAA-positive cells.     

Filtration of Green Algae and Cyanobacteria by Freshwater Mussels in the Partitioned Aquaculture System

Abstract.— The freshwater mussel Elliptio complanata was provided water containing green algae and cyanobacteria delivered from the Partitioned Aquaculture System (PAS) at eight flow rates to determine algal filtration rates as mg of particulate organic carbon (POC)/kg wet tissue weight per h. The dominant taxon in cyanobacterial waters was Microcystis while the dominant taxa in green algal waters were Scenedesmus and Ankistrodesmus . The cell counts of Scenedesmus and Ankistrodesmus were the only algal taxa that were significantly different between the incoming water and water filtered by mussels. Filtration rates of POC obtained from green algal water were significantly greater than from cyanobacteria-dominated waters at all flow rates. A significant increase in mean filtration rate was observed as flow rates increased. The filtration rate of green algae increased as POC concentration increased, peaking at 28 mg C/L. A maximum filtration rate was not observed with cyanobacterial waters.     

Plasma digoxin concentration in dogs with mitral regurgitation.

Fifteen and eight mature beagles, without (normal group) and with experimental mitral regurgitation (MR group), respectively, were given 0.02 mg/kg/day digoxin powder for 10 days orally. The optimum time for sample collection after administration of digoxin was observed to be 8-18 hr and 10-22 hr in the normal and MR groups, respectively. In both groups, a stable concentration was reached after 3-5 days of treatment. No differences in plasma level were observed between sexes. The optimum concentration of digoxin was attained at an earlier stage than has been previously reported for both dogs and humans.     

Seasonal changes in serum total thyroxine, free thyroxine, and canine thyroid-stimulating hormone in clinically healthy beagles in Hokkaido.

The purpose of this study was to evaluate seasonal influences on thyroid hormone levels of healthy outdoor dogs in Hokkaido. We surveyed serum basal total thyroxine (tT4), free thyroxine (fT4), and canine thyroid-stimulating hormone (cTSH) levels, and tT4 levels after administration of TSH for a year. Basal tT4 levels decreased in January, and increased in August and September. fT4 levels increased in January and November. No significant seasonal variation was found in cTSH. tT4 levels after administration of TSH in August and November increased. These results suggested that the thyroid gland may have been activated in November. We should take seasonal variation into consideration when thyroid function is tested.     

Neurotrophins and the Thymus: Morphological Analysis of Mice Carrying a Non-functional Mutation on the Trka and Trkb Genes

Veterinary Research Communications -     

Prevalence and clinical implications of anthelmintic resistance in cyathostomes of horses.

OBJECTIVE: To determine the prevalence and clinical implications of anthelmintic resistance in cyathostomes of horses. DESIGN: Prospective study. ANIMALS: 80 horses on 10 farms in a 5-county region of northeast Georgia. PROCEDURE: On each farm, horses were stratified in descending order according to pretreatment fecal egg count (FEC), blocked into groups of 4, and then randomly assigned to 1 of 4 treatment groups: no treatment (controls), and treatment with pyrantel pamoate, fenbendazole, or ivermectin. Fecal samples were collected 24 hours prior to treatment and 2, 4, and 6 weeks after treatment for determination of FEC. Mean percentage of reduction in FEC was then calculated for each treatment group. For horses from each farm, the efficacy of each anthelmintic was categorized on the basis of mean percentage of reduction in FEC at 2 weeks after treatment (< 80% reduction = ineffective; 80 to 90% reduction = equivocal; and > 90% reduction = effective). RESULTS: Pyrantel pamoate was effective at reducing FEC in horses from 7 farms, ineffective in horses from 2 farms, and equivocal in horses from 1 farm. Fenbendazole was ineffective at reducing FEC in horses from 9 farms and equivocal in horses from 1 farm. Ivermectin was effective at reducing FEC in horses from all 10 farms. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that cyathostome resistance to fenbendazole is highly prevalent, and resistance to pyrantel pamoate is high enough to warrant concern. Resistance to ivermectin was not detected. On the basis of these data, it appears that ivermectin continues to be fully effective in horses. However, too few farms were used in this study to determine the prevalence of cyathostome resistance to ivermectin. Therefore, the efficacy of ivermectin should continue to be monitored closely.     

Hyperadrenocorticism associated with excessive sex hormone production by an adrenocortical tumor in two dogs.

An 11-year-old spayed female Labrador Retriever and a 9-year-old castrated male miniature Poodle were evaluated because of clinical signs of hyperadrenocorticism. Cortisol testing did not support a diagnosis of hypercortisolemia in either dog; however, imaging studies revealed unilateral adrenal tumors in both dogs. Serum concentrations of 17-hydroxyprogesterone, progesterone, and estradiol were high in both dogs, and androstenedione concentrations were also high in 1 dog. It is suspected that sex hormone secretion by the adrenal tumors in these dogs resulted in clinical signs of hyperadrenocorticism. Clinical signs and hormonal abnormalities resolved in the male dog after surgical resection of the tumor. There was no improvement in clinical signs after treatment with mitotane in the female dog, which died 2 months after diagnosis. Histologic evaluation confirmed the presence of adrenocortical carcinoma in both dogs.     

Hypercalcaemia associated with chronic lymphocytic leukaemia in a Giant Schnauzer.

A 7-year-old male Giant Schnauzer was referred with a history of severe vomiting, lethargy, weight loss, polydipsia and polyuria. Detailed investigations revealed leucocytosis with a marked lymphocytosis, mild non-regenerative anaemia, thrombocytopenia, hypercalcaemia and azotaemia. Circulating lymphocytes were small and well-differentiated, and the same lymphoid population was present in bone marrow. Chronic lymphocyctic leukaemia with associated paraneoplastic hypercalcaemia was diagnosed. Immunohistochemical staining of a bone marrow biopsy revealed a neoplastic B-cell line expressing CD79. The dog responded to therapy with prednisolone and chlorambucil for a period of 8 months.     

The effect of dietary chloride and bicarbonate on blood pH, haematological variables, pulmonary hypertension and ascites in broiler chickens.

1. The effect of supplementing grower diets with bicarbonate or chloride on haematological variables, pulmonary hypertension syndrome and ascites in broilers exposed to cold temperature was investigated. 2. High concentrations of dietary chloride had no effect on the pH of the venous blood but a low chloride/high bicarbonate diet significantly increased blood pH. There was no consistent effect of dietary chloride or bicarbonate concentrations on growth performance, although in 1 experiment birds given a low chloride/high bicarbonate diet consumed less food and gained less weight than controls. 3. Birds fed on high-chloride diets tended to have a higher incidence of ascites and pulmonary hypertension than controls. Birds fed on low-chloride and high-bicarbonate diets had significantly lower pulmonary hypertension and lower heart weights, which may have indicated a decrease in pulmonary and systemic blood pressure. 4. We conclude that increasing dietary bicarbonate and reducing dietary chloride has potential as a low cost and effective method to reduce the pulmonary hypertension which leads to ascites in broiler chickens.