Pathology of experimentally induced polybrominated biphenyl toxicosis in pregnant heifers.

Toxicosis was induced in pregnant Holstein-Friesian heifers by giving polybrominated biphenyls a in gelatin capsules at the rate of 25 g/day. Initially, this dosage was approximately 67 mg/kg of body weight. Clinical signs were anorexia, excessive lacrimation and salivation, diarrhea, emaciation, dehydration, depression, and abortion. Fever was not evident during the experiment. Values for serum glutamic-oxalacetic transaminase, lactic dehydrogenase, blood urea nitrogen, and bilirubin were increased. Changes in packed cell volume, hemoglobin content, total erythrocyte and leukocyte counts, and differential leukocyte counts were minimal and reflected dehydration and secondary infection. The principal urine changes were decreased specific gravity and moderate proteinuria. Gross necropsy findings included dehydration; subcutaneous emphysema and hemorrhage; atrophy of the thymus; fetal death with concomitant necrosis of cotyledons; kidneys that were enlarged, pale tan to gray; thickened wall of the gallbladder; inspissated bile; edema of abomasal folds; mucoid enteritis; linear hemorrhage and edema of the rectal mucosa; and secondary pneumonia. Microscopic changes were most marked in the kidneys, gallbladder, and eyelid. In the kidney, the principal changes were extreme dilatation of collecting ducts and convoluted tubules, with epithelial degenerative changes of cloudy swelling, hydropic degeneration, and separation from the basement membrane. Common changes in the gallbladder were moderate to marked hyperplasia and cystic dilatation of the mucous glands in the lamina propria. The changes in the eyelids were characterized by hyperkeratosis, with accumulations of keratin in hair follicles of the epidermis and squamous metaplasia with keratin cysts in the tarsal glands. Clinical signs and lesions of toxicosis did not develop in heifers given the polybrominated biphenyls at the rate of 0.25 mg and 250 mg/day for 60 days. Initially these rates were approximately 0.00065 mg/kg and 0.65 mg/kg of body weight, respectively.     

Changes in hepatic function tests to induced toxicity in the bovine liver

Graded hepatic damage was induced in mature lactating dairy cows to measure the sensitivity of several hepatic diagnostic tests. In a preliminary study, cows were dosed with .05, .10 and .20 ml/kg body weight of carbon tetrachloride. Extreme changes occurred in hepatic tests by 24 h post-dosing, and all died by 35 h with massive diffuse centrilobular necrosis of hepatic cord cells. Dosing was decreased to induce non-fatal hepatic changes. Cows in Groups 1, 2, 3 and 4 were orally dosed with .002, .004, .006 or .01 ml/kg body weight of carbon tetrachloride, respectively. Serum enzymes of hepatic origin, bilirubin, plus bromosulfophthalein dye clearance were assayed before dosing and up to d 14 post-dosing. Liver biopsies were performed 24 h post-dosing for histological evaluation and cytochrome P-450 content. Hepatic concentrations of cytochrome P-450 were decreased in all the dosed cows. Serum activities of sorbitol dehydrogenase and gamma-glutamyl transferase were elevated in cows of Groups 3 and 4 and glutamic-oxaloacetic transaminase in cows of Group 4 by 24 h. Serum alkaline phosphatase, glutamic-pyruvate transaminase, lactate dehydrogenase, bilirubin, urobilinogen and bromosulfophthalein dye clearance were not significantly different. Mild to moderate diffuse centrolobular necrosis was observed in livers of cow of Groups 3 and 4, but no pathological changes were seen in Groups 1 and 2.     

A Proposed Role for VEGF Isoforms in Sex-Specific Vasculature Development in the Gonad

Many scientists have expended efforts to determine what regulates development of an indifferent gonad into either a testis or ovary. Expression of Sry and upregulation of Sox9 are factors that initiate formation of the testis-specific pathway to allow for both sex-specific vasculature and seminiferous cord formation. Migration of mesonephric precursors of peritubular myoid cells and endothelial cells into the differentiating testis is a critical step in formation of both of these structures. Furthermore, these events appear to be initiated downstream from Sry expression. Sertoli cell secretion of growth factors acts to attract these mesonephric cells. One hypothesis is that a growth factor specific for these cell linages act in concert to coordinate migration of both peritubular and endothelial cells. A second hypothesis is that several growth factors stimulate migration and differentiation of mesonephric 'stem-like' cells to result in migration and differentiation into several different cell lineages. While the specific mechanism is unclear, several growth factors have been implicated in the initiation of mesonephric cell migration. This review will focus on the proposed mechanisms of a growth factor, Vascular Endothelial Growth Factor, and how different angiogenic and inhibitory isoforms from this single gene may aid in development of testis-specific vascular development.     

Medial collateral ligament desmitis of the distal interphalangeal joint in the hindlimb of a horse: treatment with cast immobilisation

A 12‐year‐old show‐jumping mare was presented for investigation of a chronic hindlimb lameness of 16 weeks duration. Perineural anaesthesia and ultrasonography localised the lesion to the medial collateral ligament of the distal interphalangeal joint of the left hindlimb. Treatment consisted of a heavily padded distal limb cast for 6 weeks, strict box rest and a strictly regulated hand walking program. Serial ultrasonographic examinations were performed throughout the rehabilitation period. Collateral ligament desmitis of the distal interphalangeal joint is a commonly diagnosed condition of the forelimb; however, hindlimb collateral ligament desmitis has been rarely reported. Ultrasonographic examination in this case was an invaluable diagnostic and follow‐up tool. Immobilisation of the foot by means of a heavily padded distal limb cast allowed excellent healing of the ligament and is presented as a novel treatment for collateral ligament desmitis. At the time of writing the mare had returned to her previous level of exercise and was showing no signs of lameness.     

Postmortem lesions in the intercarpal ligaments of the equine midcarpal joint

Objective To determine the frequency of damage to the medial palmar intercarpal ligament (MPICL), and the range of sizes of the dorsomedial intercarpal ligament (DMICL) of the midcarpal joint in horses with no history of carpal joint disease.
Materials and methods
Cadaver limbs were collected from 72 horses with no history of carpal joint disease. One hundred and forty-two midcarpal joints were dissected and the MPICL and DMICL were examined. Measurements were made with a digital micrometer.
Results MPICL tearing was present in 88 of 96 joints from horses 2 years and older. Tears were predominantly of the dorsolateral bundle and complete rupture of the dorsolateral and dorsomedial bundles was not observed. Tearing was not present in foals less than 4 months of age and the severity of tearing increased significantly with age (P < 0.0001). Severity of tearing was significantly greater in racing Standardbreds than racing Thoroughbreds (P < 0.01), but there was no significant difference between racing and non-racing horses. The lateromedial thickness of the DMICL ranged from 0.4 mm to 2.6 mm in horses 2 years and older. Lateromedial thickness increased significantly with age, and was significantly greater in racing Standardbreds than racing Thoroughbreds (P < 0.01). There was no significant difference between racing and nonracing horses.
Conclusions Damage confined to the dorsolateral bundle of the MPICL is a common finding in horses over 1 year of age and is probably of little clinical significance. Complete rupture of both dorsolateral and dorsomedial bundles is uncommon in horses with no history of midcarpal joint disease. Variation in size of the DMICL is observed in horses of all ages, but is most marked in 2-year-old horses.     

Effects of increasing ultraviolet B radiation on decomposition and soil organic matter dynamics: a synthesis and modelling study

The net effect of increasing ultraviolet B radiation levels on ecosystems is unknown. Most of the relevant ecological research has focused on the responses of living plants and algae to ultraviolet B exposure, with little attention directed toward other groups. However, research in such diverse areas of study as the degradation of textiles, pigments, synthetic polymers, paper, cellulose, wood, and museum artifacts show that ultraviolet light is a significant factor in the decay of many organic compounds. In aquatic ecosystems, the photochemical degradation of recalcitrant, dissolved organic compounds is increased by ultraviolet B exposure, and similar reactions could make important contributions to organic matter turnover in terrestrial ecosystems. This hypothesis is supported by observed patterns of decomposition of exposed surface litter in arid and semi-arid environments. Since plant lignins are both photochemically reactive and form a significant component of soil organic matter, ultraviolet B-induced lignin degradation could alter material cycling in terrestrial ecosystems. However, results of a model simulating the potential effects of ultraviolet B-induced lignin degradation suggest that higher rates of litter turnover may have only slight effects on soil organic matter dynamics.     

Derivation, safety and efficacy of a Marek's disease vaccine developed from an Australian isolate of very virulent Marek's disease virus

Objective To develop a serotype 1 Marek's disease (MD) vaccine from a very virulent MDV (vvMDV) pathotype and demonstrate safety and efficacy against early challenge with very virulent field strains in the presence of maternal antibody.
Study design Strain BH 16 was isolated and attenuated by serial cell culture passage. One of two cloned passages was selected for vaccine development following early laboratory-scale protection trials in commercial birds. Comparative protection trials were carried out on the BH 16 vaccine and on a CVI 988 Rispens vaccine using commercial and SPF chickens. Challenge viruses used were either a low passage strain BH 16 virus, the Woodlands No. 1 strain or MPF 57 strain of MDV. The BH 16 vaccine was back-passaged in SPF chickens six times and virus recovered from the final passage and the original vaccine virus were tested for safety. The immunosuppressive potential of the BH 16 and Rispens vaccines was also assessed in parallel.
Results The BH 16 and Rispens vaccines induced comparable levels of protection when used as monovalent or multi-valent vaccines, although protection achieved with the mono-valent vaccines was lower. No gross tumour formation was evident in any birds receiving the BH 16 vaccine or bird-passaged virus, although microscopic lesions were present in 2/12 birds that received the bird-passaged virus. In tests for immunosuppression, there was no histological evidence of damage to either the bursa of Fabricius or the thymus.
Conclusion The BH 16 vaccine was shown to be safe and at least as protective as the Rispens vaccine against three highly virulent MD challenge viruses.     

沙棘叶水提物适应原性及安全性评价

本文评估了沙棘叶水提物在大白鼠体内的适应原活性和毒性.提取物的剂量依赖性适应原活性的研究采取将小鼠置于低温(5℃),低压(428mmHg),抑制(C-H-R)的环境下的30min前口服不同剂量的沙棘叶水提物.在亚急性毒性中,连续14d每天口服10倍和20倍最大有效剂量（每天口服1g/kg体重和2g/kg体重）和连续30...