Dynamics of Protein 27 of Avian Leukosis Virus and Transforming Growth Factor β2 in Lymphoid Leukosis Susceptible and Resistant Broiler Chicken Breeding Stock

The dynamics of the serum concentration of protein 27 (P27) of avian leukosis virus and transforming growth factor ₂ (TGF-₂) were compared during the period between 29 and 59 weeks of age in two flocks of broiler chicken breeding stock undergoing outbreaks of severe lymphoid leukosis (LL) associated with persistent high mortality (susceptible) and in another two flocks of breeding stock with the presence of avian leukosis virus in association with low mortality due to LL (resistant). The average mean concentration of serum P27 in the LL-susceptible flocks was significantly higher (<0.05) than that in the LL-resistant flocks in six out of seven samplings performed at 5-week intervals, between 29 and 59 weeks of age. The peak in the average rise of serum P27 in the LL-resistant flocks (309 pg/ml) was associated with the highest level of TGF-₂ (1282 pg/ml) among all flocks and at all sampling times. The significance of TGF-₂ in inhibition of lymphoid tumour development is discussed.     

EFFECT OF HYDRATION ON SIGNAL INTENSITY OF GELATIN PHANTOMS USING LOW-FIELD MAGNETIC RESONANCE IMAGING: POSSIBLE APPLICATION IN OSTEOARTHRITIS

Five gelatin phantoms were constructed to study the effect of matrical hydration on magnetic resonance imaging (MRI) signal intensity using a low-field strength imager. Water content of the phantoms ranged from 75 to 95% weight/weight. Signal intensity values of each phantom were measured using five imaging sequences: proton density, T1-weighted, T2-weighted, inversion recovery with short inversion time, and inversion recovery with long inversion time. There was significant positive correlation (p < .05) of signal intensity with differences in hydration using the T2-weighted sequence and the inversion recovery sequence with short inversion time. Significant negative correlations (p < .05) were found with T1-weighted imaging and the inversion recovery sequence with long inversion time. In a second part of the study, in vivo focal variations in MRI signal intensity were evaluated in a canine cranial cruciate ligament deficient model of osteoarthritis. Signal intensity measurements were obtained from multiple areas of articular cartilage to identify an initial stage in osteoarthritis that is characterized in part by increased hydration of articular cartilage. At 6 weeks post-transection of the cranial cruciate ligament, an increase in signal intensity was detected in the articular cartilage of the weight-bearing portion of the lateral femoral condyle and the caudal portion of the medial tibial condyle with T1-weighted imaging. The increase in signal intensity may reflect increased proteoglycan synthesis by chondrocytes that also occurs early in the pathogenesis of osteoarthritis.     

Enhancement of phagocytosis and bacterial killing by heterophils from neonatal chicks after administration of Salmonella enteritidis-immune lymphokines

During the first week post-hatch, chickens demonstrate an increased susceptibility to infection by bacteria such as Salmonella. The purpose of the present study was to evaluate the effects of immune lymphokines on phagocytosis and killing activities of heterophils in chicks during the first 1-7 days of life. Lymphokines isolated from chicken splenic T-cells harvested from Salmonella enteriditis (SE)-hyperimmunized hens (SE-ILK), have in past experiments, demonstrated augmentation of heterophil activity in day-of-hatch chicks resulting in protection from SE organ invasion. The present experiments reveal significant increases (p<0.05) in heterophil phagocytosis and killing when comparing chicks treated with SE-ILK to control groups in vitro. In SE-ILK-treated groups, a two-fold or greater increase is noted in heterophil phagocytosis within I h of incubation as compared to controls. Heterophils isolated from 1-day-old and 4-day-old chicks treated with SE-ILK killed significantly greater numbers (p<0.05) of SE than heterophils isolated from control groups. By Day 7 post-hatch, significance is not noted in the killing activity of heterophils from treated groups when compared to control groups. However, heterophils from SE-ILK groups continue to kill greater numbers of SE than control groups. These data support SE-ILK augmentation results in an enhanced heterophil function in chicks during the greatest period of susceptibility to Salmonella invasion.     

Lesions and transmission of experimental adenovirus hemorrhagic disease in black-tailed deer fawns

Adenovirus infection was the cause of an epizootic of hemorrhagic disease that is believed to have killed thousands of mule deer (Odocoileus hemionus) in California during the latter half of 1993. A systemic vasculitis with pulmonary edema and hemorrhagic enteropathy or a localized vasculitis associated with necrotizing stomatitis/pharyngitis/glossitis or osteomyelitis of the jaw were common necropsy findings in animals that died during this epizootic. To study transmission of adenovirus infection in deer and susceptibility of black-tailed deer (Odocoileus hemionus columbianus) fawns to adenovirus infection, six 3-6-month-old black-tailed fawns were divided into two treatment groups. One group was inoculated intravenously and the other group was inoculated through the mucous membranes of the eyes, nose and mouth with purified adenovirus. Each treatment group also included two additional fawns (four total) that were not inoculated but were exposed to inoculated animals (contact animals). One fawn served as a negative control. Between 4 and 16 days postinoculation, 8/10 fawns developed systemic or localized infection with lesions identical to lesions seen in animals with natural disease that died during the epizootic. Transmission was by direct contact, and the route of inoculation did not affect the incubation period or the distribution of the virus (systemic or the localized infection). Immunohistochemical analysis using polyclonal antiserum against bovine adenovirus type 5 demonstrated staining in endothelial cells of vessels in numerous tissues in animals with systemic infection and endothelial staining only in vessels subtending necrotic foci in the upper alimentary tract in animals with the localized form of the disease. All inoculated or exposed animals had staining in the tonsillar epithelium. Transmission electron microscopic examination of lung and ileum from two fawns with pulmonary edema and hemorrhagic enteropathy demonstrated endothelial necrosis and adenovirus virions in endothelial cell nuclei. Adenovirus was reisolated in black-tailed deer pulmonary artery endothelial cells using lung homogenate of the first fawn that developed systemic adenovirus infection. Serum virus neutralization test results suggest that this deer adenovirus is a new serotype.     

Prevalence and persistence of Salmonella in broiler chicken flocks.

Cecal contents of 2,345 broiler chickens consisting of 28 flocks originated from 12 farms were examined for the prevalence of Salmonella to know the actual status of infection with Salmonella in the chicken flocks. Salmonella was isolated from 336 (14.3%) samples. From these isolates, eight serovars were identified. Of the 336 Salmonella isolates, 242 (72.0%) were serotyped as S. Blockley, 60 (17.9%) S. Hadar, 15 (4.5%) S. Bredeney, nine (2.7%) S. Schwarzengrund, four (1.2%) S. Anatum, three (0.9%) S. Enteritidis, two (0.6%) S. Ohio, and one (0.3%) S. Livingstone. The same serovars of Salmonella were repeatedly found in the chickens from the same farms. S. Typhimurium and S. Enteritidis were detected in pooled broken eggshell samples collected from the hatchery. Analysis of plasmid profiles revealed 11 patterns of S. Blockley and seven patterns of S. Hadar. Strains of the same plasmid profiles of S. Blockley were isolated repeatedly from the same farm over one year after the first isolation.     

Serotypes and electrophoretic protein profiles of Pasteurella haemolytica isolated from pneumonic ovine lungs.

Serotypes and SDS-PAGE protein profiles of P. haemolytica isolated from pneumonic ovine lungs were investigated. Of 268 P. haemolytica isolates, 232 (86.6%) were serotypable. A total of 12 serotypes were recognized in 20 different geographic origins of central Turkey. The most common serotype was A2, followed by A7, A1 and T4. Serotypes A13, A14, A16 and T15 could not be detected. In SDS-PAGE, marked differences between major bands of biotype A and T strains were found. In numerical analysis of protein profiles, biotype A and T strains were separated at 58% similarity level. Biotype A isolates produced a cluster at 80% similarity level, and biotype T isolates at 92% similarity level. No single cut off level was able to discriminate between each serotype studied and isolates could not be clustered on the basis of their geographic origins.     

Ubiquitin gene expression and ubiquitin conjugation in chicken muscle do not reflect differences in growth rate between broiler and layer birds.

Previous work has shown that chicken strains selected for growth (broilers) degrade muscle proteins less rapidly than those selected for egg laying. They also have decreased calpain and increased calpastatin content in breast muscle. This study aimed to test the hypothesis that these differences correlate with changes in the ATP- and ubiquitin-dependent proteolytic system. Chickens of a broiler strain (Ross 1) and a layer strain (ISABrown) were reared to the age of 4 wk under identical conditions with ad libitum access to feed and water. Mean fractional growth rates were 10.4%/d for broilers and 7.4%/d for layers. Feed intake measured in the last week of the trial was slightly greater in layer birds (.11 and .12 g x g body weight(-1) x d(-1) for broilers and layers respectively; P < .006). Polyubiquitin (UbI) messenger RNA was abundant in the muscles of these well-fed birds, but it showed little difference between strains. Muscle did not significantly express the UbII polyubiquitin gene. The ATP-dependent system conjugating ubiquitin to endogenous proteins had greatest activity in the gastrocnemius muscle of broiler birds but was not significantly different between breeds. Proteins cross-reactive with antisera to recombinant human proteasome regulatory subunits MSS1 (multicopy suppressor of SUG 1; S7) and TBP1 (tat binding protein 1; S6') were present in muscle homogenates from both strains of bird. The chick equivalent of TBP1 was more abundant in breast muscle of broiler birds than in leg muscle, or in either muscle of layers. Antiserum to recombinant yeast subunit mts2 (mitosis temperature sensitive gene 2; S4) did not react with any protein of the expected size but detected a 30-kDa peptide that was not associated with the 26S proteasome; this was found only in muscle from the layer strain. Hence, during normal growth of chickens, rates of protein degradation are not controlled by the expression of ubiquitin mRNA or the conjugation of ubiquitin. However, the composition of the 26S proteasome may be a regulatory factor.     

Performance, serum characteristics, carcase traits and lipid metabolism of broilers as affected by supplement of chromium picolinate.

1. This study investigated the effects of dietary supplementation with chromium picolinate on the performance, serum and carcase traits and lipid metabolism of broilers. In trial 1, 120 1-day-old broilers with an equal number of males and females were assigned at random to 4 groups with 3 replicates. Four treatments with dietary supplements of 0 (control), 800, 1600 and 3200 microg/kg of chromium picolinate were used. In trial 2, 6-week-old broilers (20) were used to determine how supplements of 0, 200, 400 and 800 microg/kg chromium in an incubation medium influence their hepatocyte lipogenic capacity and adipocyte lipolysis, in vitro. 2. Dietary supplements of 1600 and 3200 microg/kg chromium in broiler diets significantly increased food consumption (P<0.05); 1600 microg/kg markedly improved weight gain (P<0.05); 1600 and 3200 microg/kg groups showed increased liver lipid content (P<0.05). However, the abdominal fat content tended to decrease in these 2 groups. 3. Dietary supplements of 1600 and 3200 microg/kg of chromium decreased serum glucose and nonesterified fatty acids (NEFA) concentrations while increasing serum phospholipid content (P<0.05). Insulin concentration decreased only in birds receiving 3200 ppb chromium (P<0.05). Serum triacylglycerol (TG) clearance rate in chromium-supplemented groups was markedly enhanced (P<0.05). 4. In addition, chromium supplemented groups had increased serum HDL contents and also reduced serum VLDL and LDL contents (P<0.05). 5. Trial 2 indicated that lipogenesis from [U-14C]glucose by isolated hepatocytes was significantly enhanced by 400 ppb chromium (P<0.05). 6. The results from this study demonstrate that a supplement of 1600 microg/kg of chromium picolinate in the ration influences the growth, carcase, serum traits and lipid metabolism of broilers.     

Equine dental disease part 1: a long-term study of 400 cases: disorders of incisor, canine and first premolar teeth.

A review of 400 horses referred because of dental disorders showed 44 cases to suffer from primary disorders of their incisors and 11 from canine or 1st premolar teeth disorders. The remaining 345 horses suffered from primary disorders of the cheek teeth. Disorders of incisors included traumatic damage to teeth and their supporting bones, retained deciduous, displaced and supernumerary incisors; brachygnathia and abnormalities of wear, with most of the latter disorders being secondary to primary disorders of the cheek teeth Only 3 cases of apical infection of incisors were recognised. Most cases of fractured incisors responded well to conservative therapy. Retained deciduous incisors were extracted, but most cases with supernumerary and displaced incisors, or brachygnathia were treated conservatively. Most disorders of the canine and 1st premolar were developmental displacements that caused bitting problems (abnormalities of head movement associated with the bit), and these cases responded well to extraction of the displaced teeth.     

Detection of T. gondii in tissues of sheep and cattle following oral infection.

It has been reported in the literature that cattle are more resistant to toxoplasmosis than sheep. Congenital disease due to T. gondii infection is rarely reported in cattle whereas the parasite is a major cause of abortion and neonatal mortality in sheep. It is believed that sheep remain chronically infected for life. Undercooked meat from infected sheep is an important source of infection for man. In contrast cattle are thought to harbour fewer parasite tissue cysts which may not persist for the lifetime of the host. Therefore, cattle are believed to pose less of a risk for human infection. In this study we examined the presence of T. gondii within a range of tissues in sheep and cattle at 6 weeks and 6 months following oral infection with 10(3) or 10(5) sporulated oocysts of T. gondii. The presence of parasite was determined by bioassay in mice and using polymerase chain reaction (PCR). The results from this study show that T. gondii was more frequently and consistently detected in sheep, in particular within brain and heart tissues, whereas parasites were not detected in the samples of tissues taken from cattle. T. gondii was more frequently detected in sheep given the higher dose of T. gondii. Examination of tissues at either 6 weeks or 6 months after infection did not appear to affect the distribution of T. gondii. The polymerase chain reaction has more specificity and sensitivity when detecting the presence of T. gondii in large animals than histological detection.