Biomedical subjects
Publications and source records attributed to W D Johnson.
An atherosclerotic aneurysm was found in aortocoronary vein grafts of two patients who had a second revascularization because of reappearance of anginal symptoms five and six years, respectively, after the initial bypass operation.
Placenta extrachorialis was diagnosed in two of 56 placentas obtained from stumtailed macaques (Macaca arctoides) after elective cesarean section. The condition was characterized by the presence of an annular ring of necrotic tissue and fibrin at the margin of the villous chorion. Because these cases occurred in two of six known primiparous females, it was suggested that thte condition may account, at least in part, for the high incidence of pregnancy-related problems observed in primiparous stumptailed macaques.
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Changes in serum lipids and reasons for these changes were evaluated in 108 medical students, Class of 1975. Serum cholesterol and serum triglycerides were analyzed in their freshman and senior years. A self-administered questionnaire was used to determine if the education in medical school or the knowledge of their freshman lipid vales motivated the students to change their diet and exercise habits. During this four-year period, there was a statistically significant decrease in the mean cholesterol levels (-10 mg. per 100 ml.), while the values increased slightly but not significantly for mean triglyceride (3 mg. per 100 ml.) and weight (2 lb.). Students with abnormal lipid values in their freshman year changed their diets more frequently than those with normal values. When the students were grouped by their change in diet and exercise habits, the largest decrease in lipid values was in those who changed both their diet and exercise. However, the changes in lipid values could not be totally attributed to the students' change in habits. Results suggest that detection and education may contribute to changes in certain risk factors associated with coronary heart disease in young medical students.
A case of gastric ruputre secondary to a trihobezoar occurred in a rabbit. A review of the literature showed that, although trichobezoars are common in rabbits, antemortem gastric rupture has not been reported previously.
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Based on a study of the prevalence of intestinal polyps in New Orleans and on international comparisons, the following conclusions are reached. 1) There is a close parallelism in the epidemiology of colon cancer and adenomatous polyps. Both conditions are statistically associated with respect to geography, anatomic localization, socioeconomic class, migration experience and time trends. 2) The strength of the association favors the notion of a direct, positive correlation between multiplicity, size and atypia of polyps, and cancer risk, equivalent to "dose-effect". 3) The epidemiologic findings are coherent with other biologic facts derived from clinical, morphological and experimental studies. 4) Adenomatous polyps are a good epidemiologic indicator of colon cancer risk and their presence should be helpful in advancing from studies of the epidemiology of colon cancer to the epidemiology of precursor lesions.
A female squirrel monkey (Saimiri sciureus) had granulomatous lesions in the liver and colon. There were many fungal organisms in sections of liver and many of these organisms had multiple buds on their surface. Although we did not prepare fungal cultures, the appearance of the organisms was sufficient to identify them as Paracoccidiodes brasiliensis, the cause of paracoccidioidomycosis (South American blastomycosis).
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Investigations were carried out to determine the lung lesions responsible for the development of pulmonary heart disease, cor pulmonale, in rats treated with monocrotaline pyrrole or monocrotaline. Animals with right ventricular hypertrophy showed microscopic lung alterations consisting of alveolar edema; fibrin thrombi with partial to complete occlusion of arteries, arterioles, capillaries, and veins; connective tissue proliferation of alveolar septae; cellular hyperplasia of septae; and medial hypertrophy of arterioles. Due to the high incidence of fibrin thrombi in animals with right ventricular hypertrophy, we believe that formation of fibrin thrombi plays a decisive role in the development of chemically induced cor pulmonale.
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During an 18-month period, gastric dilatation was recognized in six guinea pigs from a colony with a monthly average of 253 animals. All of the affected guinea pigs were breeders and ranged in age from 8 to 26 months. Clinical signs were tachycardia, dyspnea, cyanosis, and marked abdominal distention. Macroscopic lesions included gastric volvulus, gastric dilatation, and splenic congestion.
A study of 540 patients who had the aortocoronary vein bypass operation (from several transplant teams) showed that grafts within a patient closed independently of one another during the first-two year postoperative period. For patients with a single vein graft, there was a 23% chance of closure during the first two year postoperative period. The chance that all grafts would close during this period for patients with two grafts was 5%, and it was 1% for patients with three grafts. The knowledge of these closure probabilities may be used by the surgeon when planning the optimal surgical maneuver.
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Only some of the diverse factors that can affect drug disposition and response in laboratory animals have been identified at the present time. These numerous factors contribute to large day-to-day variations that have become a major problem impeding investigation of drug disposition and response in laboratory animals. Although these variations render many experiments difficult to interpret and produce large discrepancies in the literature, few published investigations using laboratory animals provide sufficient details to permit replication of the studies under similar conditions with respect to these variables. Thus, the importance of these variables in affecting results is apparently insufficiently recognized at present. Two commonly overlooked variables affecting the activity of hepatic microsomal enzymes (HME) in rodents and hence the rate at which rodents eliminate from their bodies many foreign compounds are the bedding under the wire mesh cage and the relative cleanliness of the environment. Numerous chemicals present in relatively low concentrations in the environment of the animal room can significantly alter HME activity. Representative of these chemicals are aromatic hydrocarbons in cedarwood bedding, eucalyptol from aerosol sprays, and chlorinated hydrocarbon insecticides, each of which induces HME activity, whereas ammonia generated from feces and urine accumulated in unchanged pans under cages may inhibit HME activity. Chloroform, identified as an environmental contaminant of the water and air of certain cities, exhibits sex and strain differences with respect to toxicity (LD50) in mice. After intraperitoneal injection, twice as much chloroform accumulated in the kidneys of males from the sensitive strain (DBA/2J) as from the resistant (C57BL/6J) strain. First generation offspring were midway between parental strains both with respect to LD50 and renal accumulation of chloroform.
Between 1968 and 1971, 252 patients with severe ventricular malfunction underwent revascularization surgery. By means of single-plane ventriculography, the ventricle was divided into six segments, three anteriorly and three inferiorly, and ejection fractions were calculated. Patients were classified into four groups according to these observations. Results were assessed in regard to relief of angina, graft patency status, surgical mortality rate, and survival as determined by actuarial life-table analysis. These results were then compared to over-all medical and surgical experience contained in the Milwaukee Cardiovascular Data Registry as well as to other reported series of medical treatment for similar degrees of coronary artery disease and impairment of left ventricular function. Comparison between the surgical and medical series suggests improved survival and improved quality of life in the surgically treated patients. Thus many patients with severe ventricular malfunction, especially if associated with angina, can be reasonably considered candidates for surgery.
Mouse strain differences suggest intermediate or multifactorial gentic control of chloroform-induced renal toxicity and death. The chloroform dose lethal to 50 percent of animals was four times higher in C57BL/6J males than in DBA/2J males. Twice as much chloroform accumulated in the kidneys of the sensitive as the resistant strain. First generation offspring were midway between parental strains for both parameters.
Serum creatine phosphokinase (CPK) and serum glutamic oxaloacetic and pyruvic transaminase (SGOT, SGPT) levels were determined in 61 patients with leptospirosis and 16 with viral hepatitis during the acute phase of illness. The CPK value was elevated in 29 leptospirosis patients and normal in all 16 hepatitis patients. Conversely, mean SGOT and SGPT levels were lower in leptospirosis patients. The CPK determination is a simple test that may provide diagnostic information in a jaundiced patient, particularly when characteristic manifestations of leptospirosis are absent. The pattern of greatly elevated CPK levels with only modest elevations in transaminase values in an acutely jaundiced patient should strongly suggest a diagnosis of leptospirosis.