Effect of selenium on sheep lymphocyte responses to mitogens

The effect of selenium (Se) on sheep lymphocyte response to mitogens was studied. In an indoor experiment lambs were fed a basal diet containing 0.13 mg Se kg-1, and supplemented with, respectively, 0.1 or 0.5 mg Se kg-1, either as sodium selenite or as selenomethionine. Enhancement of the proliferative response of lymphocytes to phytohaemagglutinin (PHA), pokeweed mitogen (PWM) and concanavalin A was found in lambs following selenium supplementation at the lower levels. The highest dietary selenium content, however, induced decreased mitogen response. Transient increases in lymphocyte response to PHA and PWM by ewes supplemented with selenium was demonstrated in one field study and a combined effect of selenium and vitamin E was seen in another. There was no stimulatory effect on the mitogen response of lymphocytes from sheep supplemented with dietary vitamin E alone.     

Isolation of koala lymphoid cells and their in vitro responses to mitogens.

Baseline parameters have been established for the successful in vitro culture of mononuclear cells from the peripheral blood (PMC) of koalas. To minimise stress-related influences and allow repeated testing of cells from the same animals, most studies were performed using blood samples from captive koalas which had become accustomed to regular handling. Ficoll-Paque density gradient fractionation of whole blood was required to prepare cell suspensions which responded well to the T-lymphocyte mitogens phytohaemagglutinin, concanavalin A and pokeweed mitogen. In contrast, very low or negligible proliferative responses were induced by the B-lymphocyte mitogens lipopolysaccharide, jacalin and protein A, even when purified PMC were cultured with a wide range of concentrations of these molecules. Using the standard approaches established with T-lymphocytes of eutherian animals, it was shown that concanavalin A-stimulated PMC produced an interleukin 2-like growth factor. The significance of these findings is discussed in the context of current knowledge and understanding of similar studies carried out using the lymphoid cells of eutherian and other metatherian animals.     

Proliferative responses of lymphocytes to mitogens in the gray, short-tailed opossum, Monodelphis domestica.

A South American opossum (Monodelphis domestica) is a model animal for studies on the health effects of exposure to ultraviolet radiation (UVR). As part of a broad evaluation of immune function in this animal, we have tested in vitro mitogenic responses using whole blood cultures. Lymphocytes proliferated in the presence of phytohemagglutinin (PHA), concanavalin A (Con A), and pokeweed mitogen (PWM), but were unresponsive to bacterial lipopolysaccharide (LPS).     

Suppression of bovine lymphocyte responses to mitogens following in vivo and in vitro treatment with dexamethasone.

Gnotobiotic calves given intramuscular injections of dexamethasone (DM, 0.5 mg kg-1 day-1) showed marked changes in haematological parameters including a neutrophilia and a lymphopaenia. Not only was there a reduction in the numbers of circulating mononuclear cells, but there was also a significant (P less than 0.01) decrease in the in vitro responsiveness of the remaining circulating peripheral blood lymphocytes to the mitogens, phytohaemagglutinin (PHA), concanavalin A (ConA) and pokeweed mitogen (PWM). Responses to all three mitogens were suppressed to a similar degree. Analysis of the circulating mononuclear cell sub-populations before and during DM treatment demonstrated a selective depletion of B cells; the T lymphocyte sub-population that expresses the gamma/delta form of T cell receptor, are CD2-, CD5+, CD8-, CD4- and constitute a major population in peripheral blood of calves. In vitro studies in gnotobiotic and conventional calves confirmed that DM was highly inhibitory for PHA responses but, in contrast to the in vivo findings, showed little effect of DM on ConA responses. Expression of surface antigens after 72 h in vitro culture in the presence of DM were little affected with the exception of BoCD8 and MHC II, which showed increased and decreased expression, respectively. These observations would suggest that distinct mechanisms are involved in glucocorticosteroid suppression of the responses to these two mitogens.     

Lymphocyte responses to mitogens and rickettsial antigens in sheep experimentally infected with Ehrlichia (Cytoecetes) phagocytophila.

Infection of sheep with Ehrlichia (Cytoecetes) phagocytophila, the causative agent of tick-borne fever (TBF), was characterised by a significant reduction in lymphocyte reactivity to the mitogens phytohaemagglutinin, concanavalin A, pokeweed mitogen and Escherichia coli lipopolysaccharide during the period of rickettsiaemia. The addition of the prostaglandin inhibitor, indomethacin, or the nitric oxide inhibitor, N(G)-monomethyl-L-arginine, had no significant effect on the suppressive effects of E. phagocytophila on lymphocyte reactivity to the mitogens. However, peripheral blood lymphocytes obtained from primed sheep proliferated in the presence of live or heat-inactivated E. phagocytophila. Antigen-specific proliferation was detected in lymphocytes samples obtained 11 to 21 days post-inoculation with E. phagocytophila.     

The effects of bovine respiratory syncytial on normal ovine lymphocyte responses to mitogens or antigens in vitro

In the present study peripheral blod mononuclear cells (MNC) obtained from normal uninfected lambs were used to study the possible effects of bovine respiratory syncytial virus (BRSV) on lymphocyte responses to the mitogens, phytohaemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) in vitro. Live BRSV had a depressive effect on the proliferative responses of normal MNC to PHA, Con A and PWM. Inactivated BRSV and a commercial preparation of prostaglandin E2 were also found to depress the proliferative responses of normal ovine MNC to PHA but recombinant tumour necrosis factor-alpha (TNF-alpha) had no such effect. Serum samples obtained from BRSV-infected lambs contained substances inhibitory to PHA-driven lymphocyte blastogenesis. Memory blastogenic responses to border disease virus (BDV) of lymyphocytes obtained from lambs previously primed with BDV were significantly reduced when lymphocytes were exposed to infectious BRSV.     

Effect of corticosteroid on porcine leukocytes: age-related effects of corticosteroid inhibition on porcine lymphocyte responses to mitogens

The effects of prednisolone sodium succinate on the responses of porcine lymphocytes to phytohemagglutinin (PHA) and pokeweed mitogen (PWM) were investigated. Sensitivity of peripheral blood lymphocytes (PBL) to the synthetic glucocorticoid, prednisolone, was related to age of the lymphocyte donor. The greatest sensitivity was found in PBL from animals less than one week old; PBL from animals between 2 to 4 months retained some glucocorticoid sensitive cells; whereas, PBL from animals older than 6 months were exceptionally resistant to steroid. Similar age-associated sensitivities were found for lymphocytes from lymph node, spleen and thymus. Significant differential sensitivities among the various lymphoid organs were found with the thymic lymphocyte possessing the greatest sensitivity to steroid and the PBL lymph node and splenic lymphocytes possessing the highest resistance to the suppressive effects of steroid. The age related differences in sensitivity to steroid did not appear to be caused by differences in the number of steroid receptors because lymphocytes from susceptible and resistant animals had similar numbers of receptors. The results suggest that the age related sensitivity may be associated with a higher percentage of sensitive thymic-derived lymphocyte in the PBL, lymph node and spleen of the younger animals. Results of this study also suggest that the adult pig (6 months) should be classified as a steroid resistant species.     

Decreased mononuclear cell response to mitogens in artificially reared neonatal pigs.

The influence of two rearing methods for neonatal pigs on mononuclear cell responses to mitogens was studied. Littermate pigs were reared artificially or on the sow. Artificially reared pigs displayed a leukocytosis (P less than 0.05) characterized by an increase (P less than 0.05) in mature and immature neutrophils. Skin-test responses to intradermal injections of phytohemagglutinin were less (P less than 0.05) in artificially reared pigs than in sow-reared controls. Lymphocyte proliferative responses to mitogenic stimulation were approximately 50% lower (P less than 0.05) in artificially reared pigs than in sow-reared pigs. These data suggest that artificial rearing lowers in vivo and in vitro lymphocyte responses in neonatal pigs.     

Duck virus hepatitis.

The present report gives a survey of the occurrence in Denmark of DVH, its symptoms,the course of the disease, transmission of infection and the posibilities of prevention and control. As it appears from Figs. 2 and 3, DVH can cause considerable losses for the individual producers, for whom it is difficult to safeguard themselves against new infections because of the resistance and stability of the DVH virus in infected premises. Three possibilities of controlling DVH are pointed out: isolation of the flocks, serum therapy and vaccination.     

鸭外周血液淋巴细胞转化MTT比色法检测的研究

为了建立鸭淋巴细胞转化检测的ＭＴＴ 比色法,对试验条件进行了研究。其检测的最佳条件为７．２ μｇ／ｍＬ的ＰＨＡ、７．５ ×１０６ 细胞／ｍＬ的细胞数、细胞培养液加入１ ％ 的ＳＰＦ鸡血清、细胞培养的时间为７２ ｈ。在此条件下,对北京鸭的外周血液淋巴细胞转化进行了检测,其结果为：２～６ 周龄鸭淋巴细胞转化率从５０．２ ％ 上升到２１２．３％ ,８ ～１６ 周龄正常鸭在１９３．０％ ～２８１．０％ 之间变动。实验结果表明,此方法可用于鸭体外细胞免疫功能的检测。     

Cryopreservation of some common nematodes of ruminants for up to 11,3 years

Infective larvae of selected batched of the following nematode species from sheep and cattle were examined for survival and infectivity (by injection into either the abomasum, the duodenum, or the jugular vein) after having been stored in liquid nitrogen for 103-136 months: Haemonchus contortus, Haemonchus placei, Ostertagia circumcincta, Ostertagia ostertagi, Marshallagia marshalli, Cooperia spp., Trichostrongylus axei, Trichostrongylus colubriformis, Trichostrongylus falculatus, Nematodirus spathiger, Nematodirus helvetianus, Oesophagostomum columbianum, Oesophagostomum radiatum, Chabertia ovina and Dictyocaulus filaria. Excluding D. filaria, a mean of 97.7% of the ovine and 96.0% of the bovine nematode larvae were alive when thawed. Compared with previous investigations in this series, little or no reduction occurred with time in either the survival or the viability of the nematodes from cattle, or in the survival of those from sheep. In contrast, the larvae developed poorly in sheep, possibly owing to parenteral treatment of the animals with ivermectin at a dosage of 0.4 mg kg-1, either 6 or 8 days before they were infected.     

Effects of muscle glycogen depletion on some metabolic and physiological responses to submaximal treadmill exercise.

The aim of this study was to investigate the effects of reduced muscle glycogen concentration on some physiological and metabolic responses during moderate intensity treadmill exercise in horses. Six Thoroughbred geldings were randomly allocated to 2 treatments (protocols A and B) or control in a 3 x 3 replicated Latin square design. In protocol A, horses performed low intensity exercise while horses in protocol B performed short bursts of high intensity exercise. Protocol A was designed to induce glycogen depletion mainly of slow twitch muscle fibers while protocol B aimed to deplete mainly fast twitch muscle fibers. Horses in the control group did not undergo exercise prior to the exercise test. Five hours after glycogen depletion, horses performed treadmill exercise at 60% VO2max at a treadmill slope of 10% until fatigue (20-30 min). The induced glycogen depletion prior to exercise had no significant effect on plasma glucose, insulin, or lactate concentrations during the exercise test, and there was no effect on glycogen utilization rate, although respiratory exchange ratios were lower in the glycogen-depleted groups. The VO2, heart rate and central blood temperature did not vary significantly between the protocols A and B and control throughout the exercise test. It was concluded that 20-30% depletion of glycogen concentration in the middle gluteal muscle resulted in a shift towards fat metabolism, but does not significantly affect heart rate, oxygen uptake, or concentrations of plasma glucose and lactate during moderate intensity exercise.     

恩诺沙星对鸭大肠杆菌在体内抗菌活性的试验

以人工诱发雏鸭大肠杆菌感染模型,采用肌注不同剂量的恩诺沙星注射液评价恩诺沙星体内抗菌活性。实验性治疗结果表明,不同剂量恩诺沙星注射液(7.50,5.63,3.16,2.32,1.78mg/kg),对鸭大肠杆菌的保护率分别为100%,100%,80%,60%,50%,而大肠杆菌对照组的死亡率为100%。恩诺沙星对鸭大肠杆菌的ED50值为2.93mg/kg。实验显示,恩诺沙星注射液对鸭大肠杆菌具有较强的体内抗菌活性。     

Influence of dietary fat on some metabolic responses of cattle to fasting

Metabolic responses were compared in Brahman cross and British cattle to 96 hours fasting from two maintenance diets; low fat (2.5 per cent fat) and high fat (9.2 per cent fat), which were isocaloric and isonitrogenous. Within breeds, the plasma concentrations of non-esterified fatty acids were increased (P less than 0.01) and the amounts of urinary urea nitrogen and creatinine excreted and respiratory quotient lowered (P less than 0.01) by feeding the high fat diet beforehand. Within dietary groups, the Brahman crosses showed a higher adaptation to a lipid fuel economy with a concomitant greater conservation of body nitrogen than the British animals. The results point to a role for dietary lipid in ameliorating bodyweight loss in cattle during periods of inadequate nutrition.     

Lymphocyte responsiveness to mitogens and quantitation of T and B lymphocytes in canine malignant lymphoma.

Two canine malignant lymphoma cases were studied, one from the time of detection of enlarged palpable lymph nodes through the terminal stage and another at the terminal stage. Hematologic and histopathologic studies were confirmative of leukemia. The lymphocyte subpopulations, T and B cells, were quantitated as identified by the presence or absence of surface immunoglobulin and erythrocyte-antibody-complement-rosette formation. The average number of B cells in the peripheral blood lymphocytes throughout the study were approximately 80%. The B cells in the lymph node lymphocytes were 82%. There was considerable fluctuation in the number of blood lymphocytes, but the percentage of T and B lymphocytes remained nearly constant. There was marked impairment in the lymphocytic response to mitogens. The results of this study indicate that the canine malignant lymphoma is predominantly a B-lymphocyte type.     

Analysis of cerebrospinal fluid from field cases of some common ovine neurological diseases.

Analysis of cerebrospinal fluid (CSF) samples from normal sheep and from cases of some common neurological diseases revealed a significant increase (P less than 0.05) in the group mean CSF protein concentration for meningitis, listeriosis and spinal abscess but not for scrapie, spinal injury, ovine pregnancy toxaemia or polioencephalomalacia. The CSF white blood cell count (WBC) was significantly increased (P less than 0.05) in the meningitis group and in those cases of listeriosis which failed to respond to antibiotic therapy. All cases of bacterial infection of the central nervous system (CNS) could be identified by the combined interpretation of the protein concentration and the differential WBC count. It is concluded that CSF analysis is useful clinically in differentiating traumatic from infective spinal lesions and toxic or metabolic lesions from bacterial meningitis in sheep.