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Biomedical subjects

P Harris

Publications and source records attributed to P Harris.

At least 343 records · Page 19Linked to original sources
PubMed1976

Cyclic changes in chloroplast structure in synchronized Euglena gracilis.

In populations of Euglena gracilis strain Z synchronized by cultivation on a repetitive light-dark cycle, chloroplasts undergo cyclic changes in strucutre. During most of the light period chloroplasts are relatively compact with closely appressed lamellae; during the dark (division) period the chloroplasts become quite distended. This change persists for at least one cycle even when the cells are left in continuous light, suggesting that the periodicity may be related more to the age of the cell than to a direct effect of light. In addition, the pyrenoid in synchronized cells has a transient existence, being present only in the first half of the light period.

Animals↗
PubMed1976

Effect of chlorphentermine on the lipids of rat lungs.

Chronic administration of chlorphentermine to rats resulted in a reduction of body weight compared to a normal control group. The weight of the heart, liver, kidney, and spleen was less in the treated group while the weight of the lungs was increased significantly. There was no change in the ratio of right ventricular to left ventricular weight in the rats treated with chlorphentermine, supporting the views that this drug does not cause pulmonary hypertension. Biochemical analysis showed that the increase in the weight of the lungs was due to the accumulation of phospholipid. All classes of phospholipid were affected, but particularly phosphatidyl choline, the tissue concentration of which increased nine times. Chlorphentermine also increased the proportion of palmitate present in pulmonary phosphatidyl choline. Histological examination of the lung after treatment with chlorphentermine showed evidence of this drug-induced lipidosis. No conclusion can as yet be reached as to the mechanism involved in the accumulation of phospholipid in the lung after chlorphentermine.

Animals↗
PubMed1976

Effects of chronic hypoxia and dietary restriction on myocardial enzyme activities.

Enzyme activities were measured in homogenates of left and right ventricles of guinea pigs after 14 and 28 days' exposure to 400 mmHg barometric pressure. All animals developed anorexia and right ventricular hypertrophy. Two control groups of animals were used, one free fed and the other restricted to the amount of food chosen by the hypobaric group. The factorial design of the experiment allowed some distinction between the effects of anorexia, hypertrophy, and hypoxia. Dietary restriction was associated with a decrease in glycogen phosphorylase, hexokinase, and succinate dehydrogenase activity and an increase in the M-subunits of lactate dehydrogenase. Myocardial hypertrophy was associated with an increase in the activity of the enzymes of the glycolytic pathway down as far as phosphoglycerate kinase and an increase in the M-subunits of lactate dehydrogenase. Chronic hypoxia seemed specifically to be associated with an increase in the H-subunits of lactate dehydrogenase and possibly a slight transient increase in succinate dehydrogenase activity. Mixing studies indicated that changes in enzyme activities were likely to be due to changes in enzyme concentrations.

Acclimatization↗
PubMed1976

Clara cells in the llama.

A study was made by light and electron microscopy of the Clara cells of two llamas born and bred at an altitude of 4,720 m in the Peruvian Andes. The Clara cells were numerous and prominent with big apical caps, many of which had been extruded into the terminal bronchioles. On electron microscopy the caps were found to contain vesicular endoplasmic reticulum. Previous studies have shown this to contain dipalmitoyl lecithin, a known pulmonary surfactant. Acute exposure to a simulated altitude of 4,270 m has been reported to increase surface tension in lung extracts of mice. Hence it may be that an animal, such as the llama, chronically exposed to high altitude requires a persistent secretion of pulmonary surfactant.

Animals↗
PubMed1975

The effect of isoprenaline and propranolol on rat myocardial ornithine decarboxylase.

The intraperitoneal injection of isoprenaline in rats caused an increase in myocardial ornithine decarboxylase activity which reached a maximum of about four times the control value one hour after the injection. The intraperitoneal injection of dl-propranolol had no effect on myocardial ornithine decarboxylase activity. The injection of dl-propranolol 30 min before the injection of isoprenaline almost completely prevented the effect of isoprenaline.

Animals↗
PubMed1975

Relationship of diet to lead poisoning in children.

Forty-six children, aged 24 to 47 months (25 controls and 21 subjects) chosen according to low and high blood lead levels respectively, were studied to ascertain the presence or absence of a relationship between dietary intake and the occurrence of plumbism (in children of low-income families). Through single-blind interviews by a nutritionist, dietary intakes were gathered, and the average daily intake of calories, protein, and iron was calculated. Hemoglobins, hematocrits, heights, weights, blood lead levels, and social demographic data had been gathered during the routine check for lead poisoning and at registration at the clinic. The mean caloric and protein intake as percent of recommended dietary allowances were equal and adequate for both controls and subjects. There was no statistically significant difference between the controls and subjects with respect to iron intake which was low in both groups. Mean hemoglobin and hematocrit levels were in the anemic range for both groups. The subjects were shorter and weighed less than the control group. Pica was more prevalent among children with plumbism. The findings of this study suggest that some factors other than dietary intake must account for the occurrence of lead poisoning in the subjects and that Blacks have a higher prevalence of plumbism in our area.

Body Height↗
PubMed1975

The pediatric internship as a teaching technique: a comparison of learning experiences in five hospitals.

Five interns joined in a collaborative study to assess their learning experiences during the internship year. A 3 times 5-inch data form was completed for each patient for whom the intern was responsible. Information was gathered on demongraphic characteristics of the patient, the teaching that involved this patient, and what skills were acquired. Nearly 30% of the patients were under 1 year of age; 55% were boys. More than one half of the contacts were in an outpatient or emergency department. Over 80% of the patients had not been seen before; continuity patients made up less than 9% of the contacts. Well-child care was the largest care category (19%), followed by respiratory problems (15%) and injuries (9%). About 40% of the contacts involved a teaching input, mainly from residents, attending physicians, and faculty. Care skills most frequently acquired were physical examination (49%), reading (15%), and interviewing (11%). Cross-tabulations showed that most learning was reported for inpatients, for patients with rare diseases, and when some teaching was involved.

Child↗
PubMed1975

The effect of swimming exercise of rat myocardial ornithine decarboxylase activity.

Within 30 minutes of swimming exercise there was an increase in myocardial ornithine decarboxylase activity. The activity continued to increase throughout the two hour period of exercise, after which it decreased again. Two hours after exercise, the enzyme activity had returned to the resting level, and four hours after exercise myocardial ornithine decarboxylase activity was slightly less than the resting level. Repeated daily exercise was associated with a diminished response on the second and third days. Subsequently however, myocardial ornithine decarboxylase activity was again stimulated by two hours of swimming exercise.

Animals↗
PubMed1975

The uptake of free fatty acid in the rat heart.

During the perfusion of isolated rat hearts with [1 - 14C]palmitate or [1 - 14C]oleate the rate of incorporation of label into lipids is greater in the microsomal fraction, less in the mitochondrial fraction, and least in the cell sap fraction. The degree of esterification is greatest in the microsomal fraction and greater for oleate than for palmitate. There is an early and high degree of labeling of phospholipid in the microsomal fraction. The specific activity of mitochondrial free fatty acids is higher than that of microsomal or cell sap free fatty acids.

Animals↗
PubMed1975

The effects of polyamines on cardiac protein biosynthesis.

Putrescine, spermine, and spermidine were able to stimulate cell-free protein biosynthesis at low Mg++ ion concentrations. The addition of polyamines to the perfusate of an isolated perfused rat heart preparation caused an increased rate of [14C]phenylalanine incorporation into myocardial protein. Spermine increased the uptake of alpha-aminoisobutyric acid into the myocardium.

Aminoisobutyric Acids↗