Characterization of antibody response to porcine reproductive and respiratory syndrome virus ORF5 product following infection and evaluation of its diagnostic use in pigs.

The sensitivity and specificity of recombinant open reading frame 5 products used in the Western blotting assay for confirmation of porcine reproductive and respiratory syndrome virus (PRRSV) serologic status were evaluated. The recombinant antigen-based assays were specifically compared with a commercial enzyme-linked immunosorbent assay (ELISA) for PRRSV antibodies using 1) PRRSV antibody-negative reference sera (n = 30), 2) naturally infected pig sera (n = 40), 3) sequential sera obtained from 24 experimentally infected pigs, and 4) sera submitted to 3 state diagnostic laboratories (n = 200). The recombinant antigen assay yielded an average increased sensitivity of 10% over the commercial PRRSV ELISA. The negative controls (group 1 sera) showed no difference between the 2 assays. This comparison confirmed that the recombinant antigen-specific assay was more sensitive than the commercial ELISA and is well suited for routine confirmation of the presence of PRRSV antibodies.     

The use of quantitative PCR for identification and quantification of Brachyspira pilosicoli, Lawsonia intracellularis and Escherichia coli fimbrial types F4 and F18 in pig feces

This field study explored the cytokine expression in intestinal tissue and serum from 19 diarrhoeic and 9 healthy pigs in herds with a long-time history of Lawsonia intracellularis-infection. The disease, proliferative enteropathy (PE), is associated with diarrhoea and poor performance in growers and haemorrhagic diarrhoea and sudden death in finisher pigs, but the immunopathology is poorly understood. Histopathology, demonstration of L. intracellularis and porcine circovirus type 2 (PCV2) in intestinal tissue by PCR, and detection of serum antibodies to L. intracellularis, were performed. The presence of IL-1β, IL-6, IL-10, IFN-α, IFN-γ, TNF-α and TGF-β in sera was determined by immunoassays, and intestinal mRNA expression of these cytokines plus IL-12p40 was determined by qPCR. Intestinal specimens from pigs with intestinal adenomatosis (n=2), proliferative haemorrhagic enteropathy or swine dysentery (n=2), and controls (n=2) were analysed by a genome wide porcine microarray. The clinical signs of PE were not always supported by the subsequent analyses, and the presence of PCV2 may have contributed to an increased mRNA expression for IFN-γ in intestinal specimens from some pigs. The limited gene expression in the microarray analyses and the limited expression of cytokines in both sera and intestines, indicate that the immune response is poorly activated in the initial course of an infection with L. intracellularis. However, the gene encoding for insulin-like growth factor binding protein 3 (IGFBP-3) was up-regulated in two pigs with prominent mucosal proliferation.     

Colorectal hamartomatous polyposis and ganglioneuromatosis in a dog

A 5-month-old female Great Dane puppy was treated for hematochezia, tenesmus, and rectal prolapse by resection of a 10-cm-long segment of colon and rectum. Grossly, the colorectal segment had diffuse mucosal and submucosal thickening with multiple polypoid nodules. The histologic diagnosis was colorectal hamartomatous polyps with ganglioneuromatosis. Duplication of PTEN was detected by quantitative multiplex polymerase chain reaction testing. The presence of 2 hamartomatous colorectal lesions with PTEN mutation is similar to human Cowden syndrome.     

Effects of clopidogrel and aspirin on platelet aggregation, thromboxane production, and serotonin secretion in horses

Background: Critically ill horses are susceptible to thrombotic disease, which might be related to increased platelet reactivity and activation. Objectives: To compare the effect of oral clopidogrel and aspirin (ASA) on equine platelet function. Animals: Six healthy adult horses. Methods: Horses received clopidogrel (2 mg/kg PO q24h) or ASA (5 mg/kg PO q24h) for 5 days in a prospective randomized cross‐over design. Platelet aggregation responses to adenosine diphosphate (ADP) and collagen via optical aggregometry, and platelet secretion of serotonin (5HT) and production of thromboxane B₂ (TXB₂) by ELISA were evaluated. In horses receiving clopidogrel, high‐performance liquid chromatography analysis for clopidogrel and its carboxylic‐acid metabolite SR 26334 was performed. Results: SR 26334 was identified in all clopidogrel‐treated horses, although the parent compound was not detected. Clopidogrel resulted in decreases in ADP‐induced platelet aggregation persisting for 120 hours after the final dose. ADP‐induced platelet aggregation decreased from a baseline of 70.2 ± 14.7% to a minimum of 15.9 ± 7.7% 24 hours after the final dose (P < .001). Collagen‐induced aggregation decreased from a baseline of 93 ± 9.5% to a minimum of 70.8 ± 16.9% 48 hours after the final dose (P < .001). ASA did not decrease platelet aggregation with either agonist. ASA decreased serum TXB₂ from a baseline value of 1310 ± 1045 to 128 ± 64 pg/mL within 24 hours (P < .01). Conclusions and Clinical Importance: Clopidogrel effectively decreases ADP‐induced platelet aggregation in horses, and could have therapeutic applications for equine diseases associated with platelet activation.     

植酸酶对不同类型的断乳仔猪日粮粗蛋白、氨基酸和能量的消化率的影响

通过对4个安装了简易T型瘘管的断奶仔猪研究表明,添加植酸酶并没有提高玉米-豆粕型日粮(试验组1)、小麦-豆粕型日粮(试验组2)和大麦-豌豆-菜籽粕型日粮(试验组4)粗蛋白和氨基酸的回肠表观消化率(AID),而使小麦-豆粕-菜粕型日粮的粗蛋白和氨基酸回肠表观消化率或粗蛋白和消化能的总消化道表观消化率(ATTD)得到了显著的提高(P<0.05)或呈提高的势态(P<0.10)。这些结果表明,氨基酸对细菌性植酸酶的反应因子取决于日粮的组成。     

Simultaneous Flow Cytometric Analysis of Phagocytosis and Oxidative Burst Activity in Equine Leukocytes

This paper describes a method for simultaneously measuring phagocytosis and oxidative burst activity in equine peripheral blood leukocytes by flow cytometry. Opsonized propidium iodide-labelled Staphylococcus aureus (PI-Sa) was used to measure the uptake of bacteria by equine phacocytes and the oxidative burst activity by oxidation of dihydrorhodamine 123. The requirements to achieve optimal activity of phagocytosis and oxidative burst are described. The advantage of the simultaneous technique is that it provides both independent and comparative values for phagocytosis and the oxidative burst, for the detection of impaired mechanisms of microbial destruction. Furthermore, the technique allows evaluation of opsonization activity in this context.     

Effects of formaldehyde fixation on equine platelets using flow cytometric methods to evaluate markers of platelet activation

OBJECTIVE: To investigate the effects of formaldehyde fixation on equine platelets using flow cytometric methods to evaluate markers of platelet activation. SAMPLE POPULATION: Blood samples from 6 Thoroughbreds. PROCEDURE: The degree of fluorescence associated with binding of fluorescein isothiocyanate (FITC)-conjugated anti-human fibrinogen antibody and FITC-annexin V in unactivated and adenosine diphosphate (ADP)-, platelet activating factor (PAF)-, and A23187-activated platelet samples in unfixed and 0.5, 1.0, and 2.0% formaldehyde-fixed samples was assessed by use of flow cytometry. RESULTS: In samples incubated with FITC-anti-human fibrinogen antibody prior to fixation, addition of 2.0% formaldehyde resulted in a 30% increase in total fluorescence in ADP- and PAF-activated samples and a 60% increase in A23187-activated samples. Fixation for 24 hours prior to addition of antibody resulted in reduced fluorescence of samples containing antihuman fibrinogen antibody for all 3 concentrations of formaldehyde in PAF-activated samples. The addition of all 3 concentrations of formaldehyde after incubation with FITC-annexin V resulted in significant increases in fluorescence in unactivated and activated platelet samples. As length of fixation time increased, there was a gradual increase in fluorescence that was significant at 24 hours. CONCLUSIONS: Because fixation with 2.0% formaldehyde results in significant changes in fluorescence in activated platelet samples containing anti-fibrinogen antibody, lower concentrations of formaldehyde should be used to fix equine platelet samples. Formaldehyde-fixed platelet samples should be analyzed within 12 hours of fixation to avoid artifactual increases in fluorescence. Fixation of samples containing FITC-annexin V should be avoided because of significant increases in fluorescence that may interfere with interpretation of results.     

The development of thermal resistance of the feather coat in broilers with different feathering genotypes and feeding regimes

1. This study compared the development of thermal resistance of the feather coat in broilers, with early or late feathering genes, and with or without the naked neck gene, allowed ad libitum or restricted feeding. 2. Male and female broilers of one of the 4 genotypes were reared to 6 weeks of age and allocated to one of the two feeding regimes. The thermal resistance of the back and crop region was measured at weekly intervals. A sample of birds were killed at the same ages and total feather weight, primary and secondary flight feather weight, liver weight and abdominal fat weight were measured. 3. All three main factors, sex, feeding and genotype, had significant effects on feather weight over time. The primary and secondary flight feathers were less affected by feed restriction than the feather coat as a whole. Birds with the naked neck gene showed a greater depression in growth rate than birds with a normal neck under conditions of restricted feeding. 4. The thermal resistance of the feathers on the back was greater in females, increased by early feather growth and decreased by restricted feeding. 5. Relative to metabolic body size, birds on restricted feeding had a greater feather weight and a smaller liver. There was a marked reduction in fat deposition, to almost negligible levels by 6 weeks of age. 6. Broilers given restricted feeding, in preparation for breeding, would benefit by a warmer environment, particularly those with feathering genotypes which confer a lower thermal resistance.     

Recombinant equine growth hormone administration: effects on synovial fluid biomarkers and cartilage metabolism in horses

REASONS FOR PERFORMING STUDY: Recombinant equine growth hormone (reGH) has recently been evaluated for effects on body condition and wound healing. It has the potential to influence articular cartilage via stimulation of IGF-1. OBJECTIVES: To investigate effects of administration on synovial joint metabolism. METHODS: Six mature horses were given 20 microg/kg bwt reGH daily for 8 weeks by i.m. injection. Three control horses were injected with sterile water. Serum and synovial fluid samples were collected at 6, 8, 11 and 16 weeks for GH and IGF-1 assays. Articular cartilage harvested at week 16 was evaluated by Western analysis using monoclonal antibodies BC-13, BC-4, 8-A-4 and CH-3. RESULTS: Concentrations of IGF-1 in serum and synovial fluid were significantly elevated (P < 0.05) at 6 and 8 weeks in the reGH group. Glycosaminoglycan concentrations in synovial fluid were significantly less than controls at these time points, suggesting that reGH may modulate proteoglycan metabolism in articular cartilage. In the reGH group, there were not any alterations in synovial fluid content of 3B3(-) epitope or aggrecan metabolite, or in aggrecan or link protein catabolites retained within cartilage, that might be expected with development of osteoarthritis. CONCLUSIONS: Intramuscular administration of reGH may be a more efficient means of delivery of IGF-1 to joints for cartilage resurfacing initiatives. POTENTIAL RELEVANCE: We found no alterations in cartilage metabolism indicative of development of osteoarthritis.     

Effect of photoperiod on hepatic growth hormone receptor 1A expression in steer calves

Photoperiod manipulation, specifically a long-day photoperiod (LDPP), increases milk production in lactating cattle. We have previously reported that the galactopoietic effect of LDPP is associated with an increase in circulating IGF-I, which seems to occur independently of changes in concentrations of GH, IGFBP-2, and IGFBP-3. This study tested the hypothesis that LDPP increases the expression of GH receptor (GHR) 1A messenger RNA (mRNA) in the liver. Two groups of Holstein steer calves (98 +/- 4 d old) were maintained indoors and exposed to LDPP (16-h light: 8-h dark; n = 6) or short-day photoperiod (SDPP; 8-h light: 16-h dark; n = 6) for 60 d. Calves were individually fed a grain- and alfalfa-based diet. Jugular blood samples were collected weekly and via cannula at 15-min intervals for a 4-h period on d 1, 26, and 55 of the study to monitor pulsatile hormone secretion. Serum was harvested and assayed for IGF-I, prolactin (PRL), and GH using RIA. Liver biopsies were obtained at 3-wk intervals to quantify changes in hepatic IGF-I and GHR 1A mRNA using real-time PCR. Steer BW increased during the study but did not differ between treatments. No differences in ADG or total DMI were observed. Relative to SDPP, calves on LDPP had higher (P < 0.05) serum IGF-I concentrations. Concentrations of PRL increased (P < 0.01) in calves exposed to LDPP compared with calves exposed to SDPP. Differences (P < 0.05) in pulsatile GH secretion were also detected. Hepatic IGF-I and GHR 1A mRNA were positively correlated with circulating IGF-I concentrations, and although both increased with time, they were not affected by photoperiod treatment. These results confirm that LDPP increases circulating concentrations of IGF-I, but this occurs independently of changes in IGF-I synthesis and GHR 1A mRNA expression in the liver. Therefore, our hypothesis that LDPP increases the expression of GHR 1A mRNA in the bovine liver is rejected.