PrP genotype and lamb birth weight in a scrapie-free environment: Is there an association?

The National Scrapie Plan (NSP) for Great Britain includes selective breeding programmes. These aim to reduce the frequencies of the ovine prion protein (PrP) genotypes at high risk of developing clinical disease (principally those containing the VRQ allele) within the national flock, and select for the low-risk ARR-containing genotypes. The aim of this work was to use available data from embryo transfer programmes in guaranteed scrapie-free environments to investigate whether there was a difference in lamb birth weight associated with the lamb's PrP genotype, which might affect survival. The first analysis utilised data from 355 Cheviot lambs born between 2001 and 2004. The analysis was then repeated using a larger data set of 737 Cheviot, Dorset and Suffolk lambs born between 1999 and 2003. The most important determinants of mean lamb birth weight were litter size, sex and recipient ewe breed, plus lamb breed in the three breed analysis. In both analyses the effects of all these variables are consistent and of the same order of magnitude. In the first analysis there was evidence for an apparent increase in mean lamb birth weight for the ARR-containing genotypes of 0.3 kg (95% C.I. 0.1–0.5 kg). Whereas, in the second data set there was evidence for a decrease in mean lamb birth weight for the VRQ-containing genotypes of − 0.6 kg (95% C.I. − 0.8 to − 0.4 kg). This had been masked in the first analysis by the categorisation of these genotypes with the ARQ/ARQ genotype. Within these flocks, in a scrapie-free environment, neither finding provides support for concerns that selection for low risk ARR-containing genotypes would be detrimental to lamb birth weight, which is considered to be the most important determinant of lamb survival. Extension of this work into field flocks, where scrapie-status cannot be easily assured, will require the collection of sufficient data to adjust for known direct effects as well as any additional potential confounding effects.     

Agreement among surgical pathologists evaluating routine histologic sections of digits amputated from cats and dogs.

Agreement among pathologists interpreting histologic specimens is an area of interest within human pathology, but little work in this area has been reported in the veterinary literature. Agreement among pathologists evaluating routine histologic sections of amputated digits from cats and dogs submitted to multiple diagnostic centers was examined. Histologic sections from surgical specimens were reviewed in a blinded fashion by two pathologists, and a comparison to the original diagnosis, as stated in the diagnostic report, was recorded. A total of 513 cases were reviewed, and complete agreement was reached in 409 (79.7%). Of the 104 instances of disagreement, 77 (74.0%) were considered to be of clinical significance. The diagnosis of keratoacanthoma was disagreed with in 19 of 21 diagnoses (90.4%). No other individual diagnosis was similarly disputed. The overall level of disagreement is large and is similar to that reported in human pathology and suggests that further study of this issue would be useful in veterinary pathology.     

Major gene resistance in Brassica napus (oilseed rape) is overcome by changes in virulence of populations of Leptosphaeria maculans in France and Australia

Resistance of Brassica napus (oilseed rape, canola) conferred by three different major resistance genes has been overcome by changes in virulence of Leptosphaeria maculans populations in France and Australia. In South Australia where B. napus cultivars with major gene resistance derived from Brassica rapa ssp. sylvestris were grown extensively, resistance was rendered ineffective within 3 years of commercial release of the cultivar. Disease severity was higher on cultivars with sylvestris-derived resistance than cultivars with polygenic resistance. This Australian situation is compared to that in France, where resistance conferred by the Rlm1 gene was overcome nation-wide in 5 years under commercial cropping practices, and also where a source of resistance introgressed into B. napus from B. juncea was rendered inefficient in 3 years in experimental field plots near Rennes.     

The carboxyterminal processing protease of D1 protein: Herbicidal activity of novel inhibitors of the recombinant and native spinach enzymes

The carboxyterminal processing protease of D1 protein (CtpA) is predicted to be an excellent target for the discovery of a general broad-spectrum herbicide. Directed and random screening of compounds against recombinant spinach CtpA (rCtpA) has led to the discovery of five different chemical classes of inhibitors. Lead compounds from each inhibitor class were investigated for their in vitro effects on the activities of both recombinant and native spinach CtpA. All of the lead compounds have K_i values of less than 50 μM when tested against rCtpA, and all except one showed competitive inhibition. Results from partially purified native CtpA from spinach were similar to those from the recombinant form of the enzyme, thus validating the use of rCtpA in the inhibitor screen. Compounds from three of the classes of CtpA inhibitors show in vivo herbicidal activity against Arabidopsis thaliana when applied either by addition to growth media or by spraying the leaves. Transgenic Arabidopsis plants which over-express CtpA showed greater resistance to the compounds than wild-type plants providing evidence that these inhibitors are directly acting against CtpA.     

The Knockdown Resistance (kdr) Mutation in Pyrethroid-Resistant German Cockroaches

A point mutation in thepara-homologous sodium channel gene has been shown to be associated with knockdown resistance (kdr) in several insect species including the German cockroach. In this study, we analyzed the genomic organization of the region where thekdrmutation resides and then performed polymerase chain reaction (PCR) and sequencing using genomic DNA as the template to detectkdrmutation in 24 pyrethroid-resistant German cockroach strains, most of which have been collected recently from the field. Thekdrmutation, G to C at nt 2979 resulting in a leucine to phenylalanine amino acid substitution, was detected in 20 strains including 2 strains from overseas (China and Germany). Our results clearly indicate that thekdrmutation is widespread in German cockroach populations. However, the super-kdrmutation detected in super-kdrhouse flies was not found in any of the 4 strains that showed higher levels of knockdown resistance. Little correlation was observed between the presence of thekdrmutation and the level of knockdown resistance, suggesting the existence of multiple resistance mechanisms in many of these strains.     

Management of disc-associated wobbler syndrome with a partial slot fenestration and position screw technique

A previously unpublished surgical technique for the management of disc-associated wobbler syndrome is described. A series of 17 middle-aged dobermanns (mean age 7·4 years) with this condition were managed by a technique of partial slot fenestration and position screw fixation of the affected disc space (C6/7 in all cases). One patient was lost to follow-up and, of the remaining 16 cases, 13 improved following surgery (81 per cent). The three failures were a consequence of incorrect placement of one of the screws. Careful evaluation of immediate postoperative radiographs allows this problem to be identified; the screw can then be correctly repositioned with an immediate return to surgery.     

Response to Insulin Treatment and Survival in 104 Cats with Diabetes Mellitus (1985–1995)

Medical records of 104 cats with diabetes mellitus were reviewed. Information from 54 cats that had multiple blood glucose concentrations evaluated at least 5 times over a minimum of 3 months, beginning at the time insulin treatment was initiated, was used to evaluate the efficacy of insulin in treating diabetes mellitus. Fourteen of 54 cats were treated with protamine zinc insulin (PZI), 26 with ultralente insulin, and 14 with lente insulin. Six, 29, and 19 cats had good, mediocre, and poor glycemic control, respectively, based on mean blood glucose concentrations, whereas 31, 21, and 2 owners thought clinical response was good, mediocre, and poor, respectively. No significant difference was found in glycemic control among cats treated with PZI, ultralente, or lente insulin. Glycemic control was significantly (P < .05) better in 33 cats without than in 21 cats with concurrent disease. All 104 cats were used to calculate survival data. Fifty-one of 104 cats were alive at the time of the study. Mean (± standard deviation [SD]) and median survival times were 24 (± 16) and 20 months, respectively, in the 51 cats still alive at the end of the evaluation, and 25 (± 4) and 17 months, respectively, in the 53 cats that had died during the period of evaluation. Pancreatic abnormalities identified in 37 cats that underwent necropsy included chronic pancreatitis (n = 17), acute to subacute pancreatitis (n = 2), exocrine pancreatic adenocarcinoma (n = 7) and adenoma (n = 1), islet cell atrophy and vacuolar degeneration (n = 27), and islet amyloidosis (n = 8). No association was found between glycemic control and islet amyloidosis or exocrine pancreatic neoplasia, or between survival time and chronic pancreatitis, islet amyloidosis, or exocrine pancreatic neoplasia. In conclusion, diabetic cats evaluated in this study showed a variable response to exogenously administered insulin, ranging from excellent to poor. By maintaining mean blood glucose concentrations under 300 mg/dL, clinical signs were improved, and owners were satisfied with insulin treatment. Concurrent potentially insulin-antagonistic diseases were common and deleteriously affected glycemic control and survival time.     

Right Dorsal Colitis

Moderate to severe ulcerative colitis of the right dorsal colon was diagnosed by necropsy or by exploratory celiotomy and biopsy in 13 horses with a primary clinical complaint of either colic, diarrhea, or weight loss. Clinical signs varied from acute fulminating diarrhea (possibly with fever), colic, dehydration, endotoxic shock and death, to a chronic condition manifested by mild intermittent colic up to several months in duration, and weight loss with or without mild diarrhea. In a large percentage of the horses, those affected had been hypovolemic and received nonsteroidal anti-inflammatory drugs (NSAID) or had received inappropriately high doses of phenylbutazone before the onset of illness. Experimental treatment of two horses with high doses of a phenylbutazone oral paste preparation (6 gm once daily for 5 days) and limitation of their water intake to approximately one half of maintenance requirement (for 5 days) resulted in reproduction of ulcerative colitis involving only the right dorsal colon, which was apparent at necropsy examination 11 and 15 days after initiation of drug use. It was concluded that localized ulcerative lesions in the right dorsal colon may be a previously unreported manifestation of toxicity due to the administration of NSAID.