In situ hybridization analysis of ovarian prostaglandin endoperoxide synthase mRNA throughout the periovulatory period of the ewe.

Cellular alterations in level of expression of mRNA encoding for prostaglandin endoperoxide synthase were quantified within ovarian tissues of sheep obtained before, during and after induction of the preovulatory surge of LH and ovulation with LHRH. This was accomplished by isotopic in situ hybridization using a selective cRNA probe to ovine prostaglandin endoperoxide synthase mRNA. A significant elevation in mRNA was detected within the theca interna of the preovulatory follicle at 8, 16 and 24 hr following administration of LHRH. Very close to the time of ovulation (ie., at 24 hr post-LHRH) a marked rise in mRNA was observed in association with epithelial cells covering the apical surface of the follicle. Ovarian cyclooxygenase metabolites of arachidonic acid produced during the ovulatory process in the ewe originate within the thecal layer and germinal epithelium of the follicle destined to ovulate.     

Acute infection of encephalomyocarditis (EMC) virus in Syrian hamsters.

One-month-old Syrian hamsters of the APA and Std: golden strains were inoculated intraperitoneally with 10(5) PFU/head of the D variant of encephalomyocarditis (EMC) virus and examined virologically and pathologically up to 7 days after inoculation. APA hamsters developed apparent hyperglycemia due to pancreatic islet cell damage while Std:golden hamsters did not. Hamsters of both strains showed clear histopathologic changes in the testis with prominent viral replication as well as in the brain, heart and exocrine pancreas. The susceptibility to EMC virus-infection was higher in males than in females and in APA than in Std: golden hamsters.     

Free-running rhythms of adrenocorticotropic hormone (ACTH), cortisol and melatonin in pigs.

In the domestic pig, a circadian rhythm of plasma cortisol occurs, with greatest concentrations in the morning and lowest concentrations in the afternoon. However, photic entrainment of the rhythms of ACTH and melatonin in pigs have not been defined clearly. This experiment was designed to evaluate free-running rhythms of ACTH, cortisol and melatonin in pigs housed in constant light (LL) and constant darkness (DD). Twelve crossbred barrows, maintained under ambient photoperiod, were catheterized and tethered individually in two environmentally controlled rooms, one with LL and the other with DD. For animals in LL, fluorescent lights provided 202 +/- 15 (mean +/- standard deviation) lux of light at 65 cm above the floors. Incandescent nightlights equipped with 7 watt red bulbs provided 7 +/- 2 lux and were illuminated continuously in both rooms. Pigs were given at least 14 d exposure to LL and DD, then samples of plasma and serum were obtained at hourly intervals for 48 hr. Plasma was assayed for ACTH, and serum for cortisol and melatonin. Periodograms were constructed to analyze the data. For this type of analysis, a statistic, Qp, is calculated, and circadian periodicity is suggested if maximum Qp (Qp max) occurs at or near 24 hr. The period of the free-running rhythms (tau) at Qp max for ACTH, cortisol and melatonin for pigs in LL (23.80 +/- .01, 23.78 +/- .01, and 23.21 +/- .02 hr, respectively) did not differ significantly from those for pigs in DD (23.39 +/- .01, 23.20 +/- .01, and 22.55 +/- .02 hr, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Characterization of and radioimmunoassay for canine thyroglobulin

Canine thyroglobulin (cTg) has been isolated and purified. It has similar electrophoretic patterns as Tg from other mammalian species. The main fraction had a MW of 660,000, whereas also fractions of a MW of approximately 1,300,000 (dimer) and 330,000 (subunit) were present. The iodine content was 0.8 to 1.0 % (w/w). cTg did not cross-react with antibodies against human Tg to a degree that would allow the use of a radioimmunoassay for human Tg for the determination of cTg in serum or plasma. Therefore a polyclonal antiserum was raised against cTg and a homologous radioimmunoassay was developed, which was sensitive (0.4 μg/l) and specific (cross-reactivity in cTg assay of human Tg, goat Tg, T₄, T₃, and DIT < 0.01 %).

Plasma Tg levels in normal dogs of both sexes and aged 3–15 years amounted to 192 ± 73 μg/l (mean ± SD, n=30). There was no relation between plasma Tg and T₄ levels.     

Efficacy of nemadectin, a new broad-spectrum endectocide, against natural infections of canine gastrointestinal helminths

Nemadectin, a new broad-spectrum endectocide, was highly efficacious against natural infections of all the major canine gastrointestinal helminths. At single oral dosages of 0.2-0.4 mg kg-1 body weight (BW), a liquid formulation administered in gelatin capsules was 100% effective in eliminating natural infections of Toxocara canis, Toxascaris leonina, Ancylostoma caninum and Uncinaria stenocephala. Tablets (267 mg) containing 4.6% nemadectin given at a rate of 1/3 tablet per 20 kg BW (0.2 mg nemadectin kg-1) were 100% active against T. canis, A. caninum and U. stenocephala. With both formulations, an increase in the dose rate to 0.6-0.8 mg kg-1 BW resulted in 99-100% elimination of Trichuris vulpis infections. No adverse reactions were observed in any of the treated dogs.     

The prevalence and identity of Sarcocystis cysts in cattle in Belgium

Muscle tissue from the oesophagus, diaphragm and heart of 100 cattle slaughtered in Belgium was examined for Sarcocystis infection by microscopic examination of tissue and artificial digestion. Intact sarcocysts or cystozoietes were recovered from 97% of the cattle examined. There was a difference in sensitivity between the method (digestion or histology) used and the muscle processed. The digestion of the oesophagus muscle resulted in the highest number of positive animals whereas the heart muscles contained most cysts during histological examination. Thin-walled cysts were recovered from all positive animals especially in the heart and they were indistinguishable from those of S. cruzi. Thick-walled cysts were recovered from 56% of animals but these could not be identified as S. hirsuta and/or S. hominis on morphological grounds. A correlation between pathological changes and the infection grade could not be proved.