Thymic branchial cysts in the dog and cat

Branchial cysts of the thymus were diagnosed in 15 dogs and 2 cats. The main clinical sign was dyspnea. Pleural effusion varied in degree from minimal to severe. In all animals, an encapsulated mass in the cranial mediastinal region was found to consist of multiple epithelial cysts embedded in a stroma of fibrous connective tissue, adipose tissue, and vessels. Surgical resection of the cysts was performed in 7 dogs; 3 dogs survived and were clinically normal for 18 to 36 months.

Myopathy in the nyala

Between January 1973 and June 1981, a total of 21 nyalas (Tragelaphus angasi) died with clinical and/or pathologic evidence of myopathy. The main clinical signs were stiffness, inability to rise, and failure to suckle in newborn fawns. Death usually occurred without premonitory signs of disease. Gross lesions were characterized by white or pale patches of skeletal or cardiac muscle. Histologically, acute degeneration or necrosis and mineralization were commonly observed in skeletal muscle. Acute necrosis of the myocardium with or without arteriolar fibrinoid necrosis was usually found in juvenile animals. Interstitial fibrosis of the myocardium with arteriosclerosis was commonly observed in adults. The plasma alpha tocopherol values of 3 affected nyalas ranged from 0.03 to 0.08 mg/dl (mean, 0.05 mg/dl). Unaffected nyalas from the same herd had a range of 0.09 to 0.24 mg/dl (mean, 0.13 mg/dl), which is low enough to be considered clinically deficient. The blood selenium values of the affected nyalas and other nyalas from the same herd ranged from 0.30 to 0.33 ppm (mean, 0.32 ppm), and were considered normal.

Excessive moderator bands in the left ventricle of 21 cats

Excessive numbers of moderator bands bridging the left ventricular septum and free wall and entangling papillary muscles were associated with heart failure and death in 21 cats. Clinical findings included dyspnea, anorexia, hypothermia, cardiomegaly, pleural effusion, plumonary edema, heart murmurs, gallop rhythm, electrocardiographic abnormalities (especially conduction disturbances), increased left ventricular end-diastolic pressure, angiocardiographic evidence of left ventricular restriction, and aortic thromboembolism. Pathologic changes included a morphologically distinct network of abnormal numbers of moderator bands in the left ventricle, left ventricular hypertrophy (younger cats--mean age, 4 years) or dilatation (older cats--mean age, 8.7 years), left atrial enlargement and hypertrophy, and pulmonary edema with heart failure cells in the alveoli. Heart weights of affected cats were significantly less than those of cats with congestive, hypertrophic, and restrictive cardiomyopathy (endocardial fibrosis), but were not significantly less than heart weights of clinically normal cats. Pathologic changes were characteristic of the syndrome grossly and histologically, but clinical findings were not clearly definable.

Dietary lipids and serum cholesterol level: change in diet confounds the cross-sectional association

In the Chicago Western Electric Company study, diet was assessed at the initial examination, in 1957-1958, of 1900 middle-aged men and again at their second examination about one year later. At the first examination, lipid composition of the diet, as summarized by a score based on the formula of Keys, Anderson and Grande (Grande, F. Predicting change in serum cholesterol from change in lipid composition of the diet. In: Lauer RM, Shekelle RB, eds. Childhood Prevention of Atherosclerosis and Hypertension. New York: Raven Press, 1980:145-53), was positively associated with level of serum cholesterol. Between the first and second examinations, however, hypercholesterolemic men were more likely than others to have reduced intake of dietary saturated fatty acids and cholesterol. As a result, at the second examination the cross-sectional linear association between the diet score and serum cholesterol concentration was significantly positive for men with initial levels of serum cholesterol less than 250 mg/dl, significantly negative for men with initial levels of 250 mg/dl or higher and not significantly different from zero for all men together. The bias introduced by change in diet among hypercholesterolemic men differs importantly from bias due to unreliability of measurement and to interindividual differences in intrinsic level of serum cholesterol, because it can produce statistically significant but spurious correlations.

Dietary vitamin A and risk of cancer in the Western Electric study

Intake of dietary provitamin A (carotene) was inversely related to the 19-year incidence of lung cancer in a prospective epidemiological study of 1954 middle-aged men. The relative risks of lung cancer in the first (lowest) to fourth quartiles of the distribution of carotene intake were respectively, 7.0, 5.5, 3.0, and 1.0 for all men in the study, and 8.1, 5.6, 3.9, and 1.0 for men who had smoked cigarettes for 30 or more years. Intake of preformed vitamin A (retinol) and intake of other nutrients were not significantly related to the risk of lung cancer. Neither carotene nor retinol intake was significantly related to the risk of other carcinomas grouped together, although for men in whom epidermoid carcinomas of the head and neck subsequently developed, carotene intake tended to be below average. These results support the hypothesis that dietary beta-carotene decreased the risk of lung cancer. However, cigarette smoking also increases the risk of serious diseases other than lung cancer, and there is no evidence that dietary carotenoids affect these other risks in any way.

Urinary calculi associated with portosystemic shunts in six dogs

Portosystemic shunts were diagnosed in 6 dogs with urinary calculi and signs of neurologic disease. Five of the dogs were initially examined because of neurologic signs, and 1 was seen because of urinary tract problems. The composition of the calculi was variable, but in all 13 episodes of calculi formation, the calculi contained an ammonium or uric acid component. One dog is being controlled under medical management; 4 of the dogs died, and 1 was euthanatized. The interpretation of pathogenesis was that decreased delivery of blood to the liver due to shunting or decreased liver function can potentially result in high blood concentrations of ammonia and uric acid, both of which are metabolic end products cleared by the kidneys; thus, the urinary tract would be an excellent environment for the precipitation of their salts.

Diet, serum cholesterol, and death from coronary heart disease. The Western Electric study

Over twenty years ago, we evaluated diet, serum cholesterol, and other variables in 1900 middle-aged men and repeated the evaluation one year later. No therapeutic suggestions were made. Vital status was determined at the 20th anniversary of the initial examination. Scores summarizing each participant's dietary intake of cholesterol, saturated fatty acids, and polyunsaturated fatty acids were calculated according to the formulas of Keys and Hegsted and their co-workers. The two scores were highly correlated, and results were similar for both: there was a positive association between diet score and serum cholesterol concentration at the initial examination, a positive association between change in diet score and change in serum cholesterol concentration from the initial to the second examination, and a positive association prospectively between mean base-line diet score and the 19-year risk of death from coronary heart disease. These associations persisted after adjustment for potentially confounding factors. The results support the conclusion that lipid composition of the diet affects serum cholesterol concentration and risk of coronary death in middle-aged American men.

Canine tuberculosis

In a survey of 15,272 canine necropsies, natural infection with Mycobacterium tuberculosis was found to have been diagnosed in eight dogs (0.05%). Clinical findings were anorexia, loss of body weight, lethargy, vomiting, and leukocytosis; radiography revealed pleural and pericardial effusion, ascites, and hepatomegaly. Granulomatous lesions with acid-fast bacilli were consistently found. Mycobacterium tuberculosis was isolated from lesions in the lungs, liver, or lymph nodes of five dogs. All eight dogs had a history of contact with human patients with tuberculosis.

Responses of male hamsters to the ear gland secretions of conspecifics

The behavioral responses of sexually experienced males toward anesthetized conspecifics were examined. Males directed more mounts and spent significantly more time investigating the ears and genital region of castrated males and diestrous females than intact males. Castrated males were treated in a similar manner to females, suggesting that the absence of an androgen-dependent factor(s) renders an animal more sexually attractive. Males were also administered paired preference tests in which they investigated the odors from the ear glands of diestrous females, castrated males, and intact males. Subjects spent significantly more time investigating the odors originating from ear glands of females and gonadectomized males than intact males. There was no significant difference in the amount of time males spent with the ears of castrated males and diestrous females. These experiments demonstrate that sexually experienced male hamsters can utilize odors associated with the ears to discriminate the gender of conspecifics.

Limitations in the use of [3H]thymidine incorporation into DNA as an indicator of epidermal keratinocyte proliferation in vitro

The validity of using the incorporation of [3H]thymidine into DNA as an indicator of epidermal keratinocyte proliferation in vitro has been investigated. Other parameters of cell proliferation, direct count of cell number and measurement of DNA content, consistently fail to correlate with changes in [3H]thymidine incorporation into DNA in primary and first passage cultures of rabbit and human epidermal keratinocytes. Maximum incorporation of [3H]thymidine precedes the active growth period by three days. Incorporation declines markedly during the proliferative period. Thymidine kinase activity decreases during the proliferative growth phase. Incorporation of another pyrimidine nucleotide precursor, [14C]aspartic acid, suggests that in epidermal keratinocytes in vitro the extent of utilization of the salvage and the de novo pathways may be inversely related. In such cases [3H]thymidine incorporation into TCA precipitable material fails to reflect accurately cell proliferation.

Effect of occupational and nonoccupational factors on the respiratory system of vinyl chloride and other workers

There are suggestions in the literature that vinyl chloride (VC) acts as a lung irritant. Respiratory questionnaires and lung function tests were administered to 174 chemical (VC) workers, 81 polyvinyl chloride (PVC) workers, 72 former VC workers, and 136 rubber workers, and 68 maintenance workers with exposure to VC, PVC, and rubber. Except for small airways obstruction associated with rubber, increased respiratory symptoms and decreased pulmonary function were not associated with working in chemicals, plastics, or rubber. Some increases in baseline pulmonary function were associated with VC exposure. Acute reductions in pulmonary function were observed in smokers working in chemicals, plastics, and rubber. Heavier cigarette smokers over 40 years of age had the most adversely affected respiratory system. Work was not associated with chronic respiratory effects, but all exposure groups experienced some acute respiratory insult.