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Biomedical subjects

H Walker

Publications and source records attributed to H Walker.

At least 91 records · Page 5Linked to original sources
PubMed1980

Therapy of primary hypothyroidism with L-triiodothyronine: discordant cardiac and pituitary responses.

Cardiac systolic time intervals were studied in ten patients with primary hypothyroidism before and during therapy with increasing doses of oral L-triiodothyronine (L-T3). Therapy was increased sequentially from 10, 20, 25 to 50 microgram of L-T3 daily on a monthly basis. On L-T3, 20 to 25 microgram/day, cardiac systolic time intervals and other peripheral responses to thyroid hormone including serum cholesterol concentration, serum creatine phosphokinase (CPK) activity, and basal metabolic rate had normalized. However, serum thyrotrophin (TSH) levels and peak TSH responses to thyrotrophin-releasing hormone (TRH) remained elevated on these doses of L-T3. As the dose of L-T3 was increased from 20 to 50 microgram/day, mean basal serum TSH levels decreased from 55 to 16 microunits/ml, and the peak TSH response to TRH decreased from 243 to 58 microunits/ml (P less than 0.001) while systolic time intervals did not decrease further. Changing to L-thyroxine (L-T4) therapy at this point resulted in further suppression of TSH secretion, without significantly altering systolic time intervals or the other peripheral responses to thyroid hormone. These data suggest (a) that some biological responses to thyroid hormone were normalized on lower doses of L-T3 than were required to normalize TSH secretion, and (b) that higher doses of L-T3 or substituting L-T4 therapy could suppress TSH secretion further without altering the other peripheral responses to thyroid hormone.

Adult↗
PubMed1979

Effects of hyperthermia on the mouse testis and its response to X-rays, as assayed by weight loss.

The effects of both hyperthermia alone and X-rays combined with hyperthermia on mouse testis have been investigated. Testis weight on heating time was observed for temperatures in the range 39.5 to 43.75 degrees C. The relationship between the reaction rate and the reciprocal of absolute temperature indicated that, over the temperature range considered, the activation energy associated with such thermal damage was (646 +/- 45) x 10(3) J mol-1. No evidence was obtained to indicate a change in slope of the Arrhenius plot over this temperature range. Finally, despite the high sensitivity of the testis to heat and X-rays, no thermal enhancement of the weight loss after irradiation was observed when thermal treatments which, if given alone would produce some observable damage, were administered immediately after irradiation.

Animals↗
PubMed1979

Clonal identification in acute lymphoblastic leukemia.

In a case of acute lymphoblastic leukemia, two distinct types of leukemia blast cells could be identified throughout the course of the disease. The initially dominant type of blast cell was sensitive to chemotherapy; the other was drug-resistant, gradually becoming dominant as the disease progressed. The cell types could be clearly separated by their morphologic and surface membrane marker characteristics. The same chromosomal constitution was present in both types of blast cells, indicating a common clonal origin. Additional chromosomal abnormalities were present in the later stages of the disease, demonstrating that a distinct subclone had proliferated. This study illustrates that in some cases of acute leukemia, disease relapse is caused by growth of drug-resistant subclones that may be clearly identified by changes in morphology and surface membrane marker characteristics.

Adult↗
PubMed1978

Myocardial function in hypothyroidism. Relation to disease severity and response to treatment.

Systolic time intervals (ST) were used to evaluate myocardial function prospectively in 29 hypothyroid patients. The patients were divided into three categories of disease severity: (1) severe hypothyroidism, (2) mild hypothyroidism, and (3) decreased thyroid reserve or "prehypothyroidism." Groups 1 and 2 showed decreased myocardial contractility with a prolonged preejection period (PEP), shortened left ventricular ejection time (LVET), and increase PEP/LVET, compared with normal controls. The STI were more abnormal (P less than .05) in group 1 than in group 2, suggesting that the severity of myocardial dysfunction correlates with the severity of the hypothyroidism. Group 3 had normal STI. Ten patients were restudied when euthyroid and showed complete normalization of their STI, supporting the thesis that hypothyroidism was the sole cause of the initial myocardial dysfunction.

Female↗
PubMed1978

A method for measuring cyto-adherence on frozen tissue sections.

A simple method for quantifying the cells adhering to frozen sections of mouse spleen using a microscope equipped with a drawing tube attachment, and a planimeter is described. It is a straightforward and reproducible technique which was been preliminarily employed to study optimal binding conditions for Esheep and EoxAC.

Animals↗
PubMed1977

Echocardiographic spectrum of posterior systolic motion of the mitral valve in the general population.

The prevalence of mitral valve prolapse has been established in selected groups of patients but not in the general population. The present study was designed to define the echocardiographic spectrum of mitral valve motion in a population of young individuals without clinical evidence of significant cardiac disease or hypertension. Echocardiograms were performed on 136 normal volunteers. Six subjects (4.4 per cent) had mitral valve prolapse. Eighteen subjects (13.2 per cent) had a lesser degree of posterior systolic motion of the mitral valve leaflets which was suggestive but not diagnostic of prolapse. Minor degrees of posterior systolic mitral valve motion may represent a variant of normal. Caution should be exercised in making the echocardiographic diagnosis of mitral prolapse until this question is settled.

Adolescent↗