Measurement of C‐peptide concentrations and responses to somatostatin,glucose infusion,and insulin resistance in horses

Reasons for performing study: Hyperinsulinaemia is detected in horses with insulin resistance (IR) and has previously been attributed to increased pancreatic insulin secretion. Connecting peptide (C‐peptide) can be measured to assess pancreatic function because it is secreted in equimolar amounts with insulin and does not undergo hepatic clearance. Hypothesis: A human double antibody radioimmunoassay (RIA) detects C‐peptide in equine serum and concentrations would reflect responses to different stimuli and conditions. Methods: A validation procedure was performed to assess the RIA. Six mature mares were selected and somatostatin administered i.v. as a primed continuous rate infusion, followed by 50 nmol human C‐peptide i.v. Insulin and C‐peptide concentrations were measured in horses (n = 6) undergoing an insulin‐modified frequently sampled i.v. glucose tolerance test, and in horses with insulin resistance (n = 10) or normal insulin sensitivity (n = 20). Results: A human RIA was validated for use with equine sera. Endogenous C‐peptide secretion was suppressed by somatostatin and median (range) clearance rate was 0.83 (0.15–1.61) ml/min/kg bwt. Mean ± s.d. C‐peptide‐to‐insulin ratio significantly (P = 0.004) decreased during the glucose tolerance test from 3.60 ± 1.95 prior to infusion to 1.03 ± 0.18 during the first 20 min following dextrose administration. Median C‐peptide and insulin concentrations were 1.5‐ and 9.5‐fold higher, respectively in horses with IR, compared with healthy horses. Conclusions: Endogenous C‐peptide secretion decreases in response to somatostatin and increases after dextrose infusion. Results suggest that relative insulin clearance decreases as pancreatic secretion increases in response to dextrose infusion. Hyperinsulinaemia in insulin resistant horses may be associated with both increased insulin secretion and decreased insulin clearance. Potential relevance: Both C‐peptide and insulin concentrations should be measured to assess pancreatic secretion and insulin clearance in horses.     

Evolution of rotavirus C in humans and several domestic animal species

Rotavirus C (RVC) causes enteric disease in multiple species, including humans, swine, bovines, and canines. To date, the evolutionary relationships of RVC populations circulating in different host species are poorly understood, owing to the low availability of genetic sequence data. To address this gap, we sequenced 45 RVC complete genomes from swine samples collected in the United States and Mexico. A phylogenetic analysis of each genome segment indicates that RVC populations have been evolving independently in human, swine, canine, and bovine hosts for at least the last century, with inter‐species transmission events occurring deep in the phylogenetic tree, and none in the last 100 years. Bovine and canine RVC populations clustered together nine of the 11 gene segments, indicating a shared common ancestor centuries ago. The evolutionary relationships of RVC in humans and swine were more complex, due to the extensive genetic diversity and multiple RVC clades identified in pigs, which were not structured geographically. Topological differences between trees inferred for different genome segments occurred frequently, including at nodes deep in the tree, indicating that RVC's evolutionary history includes multiple reassortment events that occurred a long time ago. Overall, we find that RVC is evolving within host‐defined lineages, but the evolutionary history of RVC is more complex than previously recognized due to the high genetic diversity of RVC in swine, with a common ancestor dating back centuries. Pigs may act as a reservoir host for RVC, and a source of the lineages identified in other species, including humans, but additional sequencing is needed to understand the full diversity of this understudied pathogen across multiple host species.     

Mycoplasma meleagridis-induced lesions in the tarsometatarsal joints of turkey embryos

Mycoplasma meleagridis (MM) has the ability to cause bone deformity in turkey poults. However, few pathological lesions have been described and no evidence of MM-induced damage to the bones has been shown. In this study, 17-day-old turkey embryos were inoculated with MM into the allantoic cavity. On the 27th day, eight of the 22 embryos presented with curved toes. Scanning electron microscopy of the tarsometatarsal joints showed fissures in the cartilage. Histological sections of the joints revealed only the infiltration of cells with eosinophilic granules. Immunohistochemical staining (IHS) showed the presence of MM in the aggregates of the bone marrow cells and the cells with eosinophilic granules. Some of these cells were harvested by laser capture microdissection (LCM), lysed, and used as template DNA. With a pair of MM-specific primers in a conventional polymerase chain reaction (PCR), a gene product was amplified, and it comigrated with the MM DNA, which indicates that these captured cells contained MM DNA. Thus, this research shows that inoculation of MM into the turkey embryos produced joint lesions and caused cellular infiltration within the bones.     

Enhancement by interferon of chicken splenocyte natural killer cell activity against Marek's disease tumor cells

A non-immune natural killer-type cell population (NK) from 6-to 12-week old chickens was able to kill MSB-1 Marek's disease (MD) tumor cells in vitro; as measured by the 51Cr-release cytotoxicity assay. Removal of T cells, B cells, adherent cells, or any combination of the three populations of cells did not result in diminished levels of cytotoxicity of the remaining spleen cells against MSB-1 cells. The cytotoxicity of chicken NK cells could be rapidly augmented by polyinosinic-polycytidylic acid (poly I:C) and by the Cal 11914 strain of Newcastle disease virus (NDV), but not by the TCND strain of NDV which is not an interferon (IFN) inducer, indicating that IFN play a role in augmentation of the NK activity in chickens.     

Seroepidemiology of marble spleen disease on a large pheasant farm in california

An agar gel precipitation (AGP) test was used to study the epidemiology of marble spleen disease (MSD) on a large pen-raised pheasant farm with a prior history of MSD. Tests conducted during early season egg production (March 1983) on previously infected breeders, poults from these breeders, and MSD-free hens introduced onto the farm, indicated absence of MSD antibodies (and clinical disease) during the breeding season (February–July 1983). Thus, a carrier state or egg transmission could not be demonstrated. The disease did not occur in late summer (September) in the same area of the ranch where it was diagnosed for the past 5 seasons. The AGP test was useful in confirming the pattern of the disease spread which moved erratically but within the general area of the index pen. Antibodies were detected in penmates approximately 10–15 days after the first observed mortality, but did not persist after the disease had run its course. Our observations suggest that the reservoir of the virus exists in the environment, and mechanical transmission (caretaker, equipment etc.) is important in sustaining the disease during an outbreak.     

Responses of ureolytic and nitrifying microbes to urease and nitrification inhibitors in selected agricultural soils in Victoria,Australia

Journal of Soils and Sediments - Urease inhibitors (UIs) such as N-(n-butyl)thiophosphoric triamide (NBPT) and nitrification inhibitors (NIs) such as 3,4-dimethylpyrazole phosphate (DMPP) have been...     

Effects of atropellis canker and stalactiform blister rust on the bending strength and stiffness of lodgepole pine lumber

Summary This study investigated the effect of Atropellis canker,Atropellis piniphila (Weir) Lohman and Cash, and stalactiform blister rust,Cronartium coleosporioides Arth., on the bending strength and stiffness of lumber from lodgepole pine,Pinus contorta Dougl. var.latifolia Engelm. The modulus of rupture, was unaffected by either disease. However, the modulus of elasticity (MOE) of lumber from infected trees, as determined by the Cook Bolinders and static bending tests, was significantly reduced from those of healthy trees. This impact should affect the use of lumber from infected trees when serviceability criteria govern the design of a structure. Should MOE-based, machine stress-rating of lumber become standard in the future, there may be an adverse, stress-related impact of these diseases on lumber value.We thank Mr. D. Hutcheson, B.C. Forest Service, Kamloops Region for advice and assistance, Messers, T. Jeanes, B. Geiselmann and D. Crabtree, Balco Forest Products Ltd., for advice, assistance, and particularly for harvesting and manufacture of the test material; Mr. L. Olsen, Forintek Canada Ltd. for assistance, and Dr. A. Harestad, Simon Fraser University for critical review. The research was supported in part by the Natural Sciences and Engineering Research Council, Canada, Operating Grant No. A3881     

Mastitis diagnostics and performance monitoring: a practical approach

In this paper a review is given of frequently used mastitis diagnostic methods in modern dairy practice. Methods used at the quarter, cow, herd and regional or national level are discussed, including their usability for performance monitoring in udder health. Future developments, such as systems in which milk-derived parameters are combined with modern analytical techniques, are discussed. It is concluded that, although much knowledge is available and science is still developing and much knowledge is available, it is not always fully exploited in practice.