B cell development in gut associated lymphoid tissues

B lymphocyte development can occur in a variety of anatomical sites. While typically considered to be a process that occurs in the bone marrow throughout life, it is becoming clear that gut associates sites of B cell development are critically important in many species of veterinary importance. Among these sites, the bursa of Fabricius in chickens and the ileal Peyer's patches of sheep are among the best studied. In these organs, it has become clear that many of the properties associated with B cell development in rodent and primate bone marrow do not apply. Thus while bone marrow B cell development typically involves an ongoing maturation of mature B cells from immature B lineage precursors that lack the expression of a surface immunoglobulin complex, gut associated lymphoid tissues (GALTs) may be colonized by a single wave of precursor cells during embryo development. Nonetheless, molecular analysis of the requirements for B lymphocyte development in GALTs reveals some striking parallels with requirements identified for B cell development in bone marrow. This article will discuss differences between B cell development in the bone marrow and GALTs and recent evidence emerging that yields insights into how these processes are regulated.     

Pharmacokinetics of phenylbutazone in beef steers

Phenylbutazone was administered intravenously to a group of 11 beef steers at a dosage of 6 mg/kg of body weight. Whole plasma and protein-free plasma were analyzed for phenylbutazone residues. Pharmacokinetic parameters of total and free phenylbutazone in plasma were calculated using a noncompartmental method. In regards to whole plasma data, the mean volume of distribution at steady state (Vss), was 140 mL/kg body weight, with a mean (+/-SEM) terminal elimination half-life (t1/2) of 34 +/- 9 h. The mean clearance was 3.2 mL/h/kg body weight. The Vss, as determined from the protein-free plasma fraction, was 54093 mL/kg body weight. This larger Vss of free phenylbutazone compared with total plasma phenylbutazone was attributed to a high degree of plasma protein binding, as well as the greater penetration of free phenylbutazone into tissues. The mean t1/2 of free phenylbutazone was 35 +/- 12 h. This similarity to the t1/2 estimated from total plasma phenylbutazone data is attributed to an equilibrium between free and plasma phenylbutazone during the terminal elimination phase. The pharmacokinetic parameters of free and total plasma phenylbutazone in beef steers are statistically similar to those previously reported for lactating dairy cows.     

High intensity exercise conditioning increases accumulated oxygen deficit of horses

High intensity exercise is associated with production of energy by both aerobic and anaerobic metabolism. Conditioning by repeated exercise increases the maximal rate of aerobic metabolism, aerobic capacity, of horses, but whether the maximal amount of energy provided by anaerobic metabolism, anaerobic capacity, can be increased by conditioning of horses is unknown. We, therefore, examined the effects of 10 weeks of regular (4-5 days/week) high intensity (92+/-3 % VO2max) exercise on accumulated oxygen deficit of 8 Standardbred horses that had been confined to box stalls for 12 weeks. Exercise conditioning resulted in increases of 17% in VO2max (P<0.001), 11% in the speed at which VO2max was achieved (P = 0.019) and 9% in the speed at 115% of VO2max (P = 0.003). During a high speed exercise test at 115% VO2max, sprint duration was 25% longer (P = 0.047), oxygen demand was 36% greater (P<0.001), oxygen consumption was 38% greater (P<0.001) and accumulated oxygen deficit was 27% higher (P = 0.040) than values before conditioning. VLa4 was 33% higher (P<0.05) after conditioning. There was no effect of conditioning on blood lactate concentration at the speed producing VO2max or at the end of the high speed exercise test. The rate of increase in muscle lactate concentration was greater (P = 0.006) in horses before conditioning. Muscle glycogen concentrations before exercise were 17% higher (P<0.05) after conditioning. Exercise resulted in nearly identical (P = 0.938) reductions in muscle glycogen concentrations before and after conditioning. There was no detectable effect of conditioning on muscle buffering capacity. These results are consistent with a conditioning-induced increase in both aerobic and anaerobic capacity of horses demonstrating that anaerobic capacity of horses can be increased by an appropriate conditioning programme that includes regular, high intensity exercise. Furthermore, increases in anaerobic capacity are not reflected in blood lactate concentrations measured during intense, exhaustive exercise or during recovery from such exercise.     

Shade effects on performance,carcass traits,physiology, and behavior of heat-stressed feedlot heifers

To determine whether shade influences performance, carcass traits, immunology, respiration rate, and behavior of cattle under conditions similar to those in commercial feedlots, we used 168 heifers in 12 soil-surfaced pens. Six pens were shaded with a galvanized steel-roofed shade (approximately 4 m high), allowing for 2.12 m2 of shade/heifer, and six pens served as the unshaded control. Heifers were fed a 90% concentrate diet during the 121-d trial that began in mid-June, performance variables (DMI, BW, ADG, gain:feed) were measured, and dietary concentrations of NEm and NEg calculated from performance data. A blood sample was collected to assess immune measures. Respiration rates and behaviors (feeding, drinking, walking, standing, lying, agonistic, and bulling) also were measured during the study. Carcass data (yield grade, kidney, pelvic, and heart fat, longissimus muscle area, hot carcass weight, quality grade, liver abscess rate, and incidence of dark-cutting beef) were collected at slaughter. Shaded heifers had higher (P < 0.05) DMI, ADG, and final BW than unshaded heifers. The gain:feed ratio and calculated dietary NEm and NEg concentrations did not differ (P > 0.26) between treatments. Most carcass traits did not differ between treatments, but more (P < 0.02) carcasses ofheifers in shaded pens graded USDA Choice than those in unshaded pens, which resulted primarily from the incidence of dark cutters being decreased (P < 0.04) by approximately half in carcasses from shaded compared with unshaded heifers. Respiration rate and percentage of circulating neutrophils were decreased (P < 0.01) for shaded compared with unshaded heifers. The treatment x time of day effect was significant (P < 0.05) for all behavioral measurements. Shaded heifers spent more time laying down (0800, 1200, and 1500, P < 0.05) and less time standing (1200 and 1500, P < 0.05) than unshaded heifers. Agonistic behavior was less (P < 0.05) for shaded than for unshaded heifers at 1900 and 2000, and bulling was less (P < 0.05) for-shaded than unshaded heifers at 2100. Results suggest that shade improved performance and altered behavior by feedlot heifers during the summertime in West Texas.     

Immunohistochemical characterisation of the lesions of canine idiopathic pericarditis

Pericardial tissue was obtained from 14 dogs with idiopathic pericarditis, and from three dogs with pericardial effusion associated with neoplastic disease, for histopathological assessment and characterisation of infiltrating leucocytes by immunohistochemistry. The major pathological change was extensive pericardial fibrosis which was generally accompanied by a mixed inflammatory response that was of greatest intensity at the cardiac surface of the tissue. Perivascular lymphoplasmacytic aggregates were present at the pleural surface and within the fibrosed pericardium. There were no features that clearly distinguished the samples from dogs with neoplastic disease from dogs with idiopathic pericarditis. The pericardial infiltrates were dominated by MAC 387+ monocyte-macrophages and plasma cells expressing immunoglobulin (Ig)A or IgG. CD3+ T lymphocytes and major histocompatibility complex (MHC) class II+ macrophages were less common, although the perivascular aggregates were mixtures of T and B lymphocytes and a proportion of fibroblasts expressed MHC class II. There was no vascular pathology or deposition of immunoglobulin or complement within vessel walls. These findings are consistent with an immune response dominated by humoral effector mechanisms (Th2 immunity) but do not clearly support a primary immune-mediated pathogenesis for idiopathic pericarditis.     

Detection of early embryonic development in chicken eggs using visible light transmission

1. In two separate experiments, the possibility of detecting embryonic development in chicken eggs was assessed using the same spectrophotometric method used to detect blood in Table eggs, using a combination of two wavelengths (577 and 610 nm) of the transmission spectrum. 2. In the first experiment, during the first 10 d of incubation, transmission spectra of 30 Hisex White eggs and 30 Hybro eggs were measured daily. 3. In the second experiment, 292 Hisex White eggs were incubated. Seven groups were randomly assigned. Six received an injection of sodium azide (NaN3) at different times during incubation in order to stop embryonic development, and during the first 12 d of incubation the transmission spectrum was measured daily. The acoustic resonance analysis method was also used on a group of uninjected eggs. 4. In the first experiment, it was possible to detect embryonic development from 120 h of incubation onwards in fertile eggs. In the second experiment changes in light transmission due to embryonic development were detected from 108 h of incubation. Detection of embryonic development using the acoustic resonance analysis method in the second experiment was possible only from 120 h of incubation. 5. It was concluded that the detection of embryonic development using visible light transmission is not directly linked with the formation of blood, but with the formation of sub-embryonic fluid, which takes place from 72 h of incubation onwards. This fluid makes the yolk sac translucent so that absorption of light at 577 nm can be detected.     

The REFLECT Statement: Methods and Processes of Creating Reporting Guidelines for Randomized Controlled Trials for Livestock and Food Safety

The conduct of randomized controlled trials in livestock with production, health, and food-safety outcomes presents unique challenges that might not be adequately reported in trial reports. The objective of this project was to modify the CONSORT (Consolidated Standards of Reporting Trials) statement to reflect the unique aspects of reporting these livestock trials. A 2-day consensus meeting was held on November 18–19, 2008 in Chicago, IL, to achieve the objective. Before the meeting, a Web-based survey was conducted to identify issues for discussion. The 24 attendees were biostatisticians, epidemiologists, food-safety researchers, livestock production specialists, journal editors, assistant editors, and associate editors. Before the meeting, the attendees completed a Web-based survey indicating which CONSORT statement items would need to be modified to address unique issues for livestock trials. The consensus meeting resulted in the production of the REFLECT (Reporting Guidelines for Randomized Control Trials) statement for livestock and food safety and 22-item checklist. Fourteen items were modified from the CONSORT checklist, and an additional subitem was proposed to address challenge trials. The REFLECT statement proposes new terminology, more consistent with common usage in livestock production, to describe study subjects. Evidence was not always available to support modification to or inclusion of an item. The use of the REFLECT statement, which addresses issues unique to livestock trials, should improve the quality of reporting and design for trials reporting production, health, and food-safety outcomes.     

Evaluation of an arthroscopic approach for transection of the equine collateral sesamoidean ligament

Objective: To evaluate: (1) an arthroscopic technique for transection of the collateral sesamoidean ligament (CSL); and (2) the healing response using magnetic resonance (MR) and microscopic examination. Study Design: Experimental study. Animals: Adult horses (n=6). Methods: Six sound horses with normal front foot radiographic and MR examinations were used. Lameness examination was performed before surgery and monthly for 12 months. Front foot radiography was performed at 180 and 360 days after surgery. Front foot MR was performed before, and at 7, 90, 180, and 360 days after surgery. Arthroscopic CSL desmotomy was performed on 1 forelimb. Gross and microscopic examination was performed on the CSL from both forelimbs at 360 days after surgery. Lameness scores were compared over time using the nonparametric Friedman's test for paired groups. CSL measurements were compared using paired t‐tests with a 2‐tailed significance level of P<.05. Results: Radiographs remained normal throughout study period. Surgery resulted in lameness on the operated limb for up to 2 months, after which all horses returned to soundness. CSL transection was confirmed during arthroscopy and with MR examination 7 days after surgery. Gross and microscopic evaluation confirmed ligament healing. Conclusions: CSL desmotomy resulted in short‐term lameness after surgery followed by healing of the CSL confirmed by gross and microscopic analysis.     

Sortase anchored proteins of Streptococcus uberis play major roles in the pathogenesis of bovine mastitis in dairy cattle

Streptococcus uberis, strain 0140J, contains a single copy sortase A (srtA), encoding a transamidase capable of covalently anchoring specific proteins to peptidoglycan. Unlike the wild-type, an isogenic mutant carrying an inactivating ISS1 insertion within srtA was only able to infect the bovine mammary gland in a transient fashion. For the first 24 h post challenge, the srtA mutant colonised at a similar rate and number to the wild type strain, but unlike the wild type did not subsequently colonise in higher numbers. Similar levels of host cell infiltration were detected in response to infection with both strains, but only in those mammary quarters infected with the wild type strain were clinical signs of disease evident. Mutants that failed to express individual sortase substrate proteins (sub0135, sub0145, sub0207, sub0241, sub0826, sub0888, sub1095, sub1154, sub1370, and sub1730) were isolated and their virulence determined in the same challenge model. This revealed that mutants lacking sub0145, sub1095 and sub1154 were attenuated in cattle. These data demonstrate that a number of sortase anchored proteins each play a distinct, non-redundant and important role in pathogenesis of S. uberis infection within the lactating bovine mammary gland.