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Biomedical subjects

A D Marks

Publications and source records attributed to A D Marks.

10 recordsLinked to original sources
PubMed1992

Longitudinal study of the amniotic fluid index in post-dates pregnancy.

Amniotic fluid (AF) was measured in 511 post-dates pregnancies (at least 41 weeks of gestational age) with the use of the AF index. Ultrasonographic evaluations were conducted on a semiweekly basis. Only patients with reliable gestational ages calculated from certain last menstrual period and confirmed by early sonographic estimates participated in the study. Oligohydramnios (AF index of 5.0 cm or less) was detected in 11.5% of the study population. Longitudinal data were available from 121 patients who demonstrated a mean 25% decrease in AF index per week beyond 41 weeks' gestation. The longitudinal change in AF index was statistically significant (P less than .0005). Amniotic fluid index measurements ranged from 1.7-24.6 cm, with a mean of 12.4 at 41 weeks' gestation. Compared with previous cross-sectional studies, this longitudinal study provides a more accurate estimate of changes in AF levels as a function of gestational age.

Amniotic Fluid↗
PubMed1991

Bone mineral density in postmenopausal women treated with L-thyroxine.

PURPOSE: To determine if bone mineral density is decreased in postmenopausal women treated with 1-thyroxine, and, if any decrease is observed, whether it is related to overtreatment with thyroid hormone, to deficiency of calcitonin, or to other factors. PATIENTS AND METHODS: The study consisted of 19 postmenopausal women between 50 and 75 years of age treated with 1-thyroxine for 5 years or longer, and 19 matching control subjects with no thyroid disease. Bone mineral density of the spine and hip was measured by dual-photon absorptiometry. Plasma calcitonin concentrations and serum thyroid hormone levels were determined by radioimmunoassays. RESULTS: The 1-thyroxine-treated women had lower bone density in the lumbar spine (1.013 g/cm2 [95% confidence interval, 0.945 to 1.081] versus 1.134 g/cm2 [1.026 to 1.242], p = 0.043); in the femoral neck (0.736 g/cm2 [0.694 to 0.778] versus 0.809 g/cm2 [0.747 to 0.872], p = 0.040); in Ward's triangle (0.576 g/cm2 [0.530 to 0.623] versus 0.694 g/cm2 [0.617 to 0.770], p = 0.011); and in the trochanteric area (0.626 g/cm2 [0.581 to 0.672] versus 0.722 g/cm2 [0.651 to 0.794], p = 0.027). The maximal increase in calcitonin following calcium infusion was 1.37 ng/L (95% confidence interval, -0.44 to 3.17) in the 1-thyroxine-treated patients versus 18.8 ng/L (95% confidence interval, 10.0 to 27.5) in normal women, p less than 0.001. The average dose of 1-thyroxine was 120 micrograms/day; 16 of the 19 patients had normal serum thyroxine levels. However, TSH levels were low in 13 of the 19, suggesting that 1-thyroxine treatment was supraphysiologic. Seven of the 19 patients had a history of hyperthyroidism in the distant past; these patients, considered separately, had significantly reduced bone density in the hip. The other 12 patients, considered separately, did not have a statistically significant loss of bone density. CONCLUSIONS: Long-term 1-thyroxine therapy is associated with decreased density of the spine and hip. Since subclinical hyperthyroidism, decreased calcitonin responsiveness, and a history of hyperthyroidism were demonstrated in some or all of these patients, these factors must be considered as possible causes of the decreased bone density.

Aged↗
PubMed1979

Enhanced adrenal responsiveness to angiotensin II in patients with low renin essential hypertension.

The plasma aldosterone response to infused angiotensin II was determined in normal controls and in patients with normal renin and with low renin essential hypertension. The patients with low renin essential hypertension showed an enhanced plasma aldosterone response when compared to the other two groups. This finding may explain why plasma aldosterone levels remain within normal limits in the face of suppressed plasma renin and angiotensin II concentrations in low renin essential hypertension.

Adolescent↗
PubMed1978

Serum cholesterol esterification in hyperthyroidism and hypothyroidism.

The rate of serum cholesterol esterification was measured in twenty healthy subjects and compared to similar data obtained with seventeen hyperthyroid and ten hypothyroid subjects. No significant differences were noted in the rate of cholesterol esterification while differences in the fractional rates were highly significant (p less than 0.001); the hyperthyroid group being higher and the hypothyroid group lower than normal. There were no clear trends observed in the changes of the rate of cholesterol esterification upon therapy. However, the fractional rates always increased when hypothyroid patients became euthyroid and always decreased in hyperthyroid patients as the result of therapy.

Cholesterol↗
PubMed1978

The pressor response to angiotensin II in patients with low renin essential hypertension.

The etiology of low renin essential hypertension (LREH) has not been established with certainty, but mineralocorticoid excess has been implicated frequently in its pathogenesis. The finding of several investigators of a normal exchangeable sodium space and extracellular fluid volume, however, does not support this hypothesis. To evaluate the possible role of sodium and water retention in LREH, the pressor response to infused angiotensin II (A II) was determined and compared to that of normal subjects and that of subjects with normal renin essential hypertension (NREH). This approach was based on the known suprasensitivity of vascular receptors to A II in situations in which sodium and water compartments are expanded as they are, for example, in proven hypermineralocorticoid states such as primary aldosteronism. In this study, we found that subjects with LREH demonstrated no increased pressor response to graded doses of A II; this suggests that LREH is not primarily mediated by sodium and water retention.

Adult↗
PubMed1978

Propranolol for the preoperative preparation of patients with thyrotoxicosis.

Thirty patients with hyperthyroidism were were prepared for subtotal thyroidectomy with propranolol. Rapid control of thyrotoxic symptoms occurred in all, and there were no undesirable drug reactions. There were no instances of post-operative thyroid storm. The drug was as effective and safe in four patients who were pregnant as it was in the other 26 patients discussed. We consider propranolol to be the drug of choice in the preoperative preparation of most patients with thyrotoxicosis.

Adolescent↗
PubMed1975

Low-renin hypertension. Occurrence in vascular complications.

Two hundred one patients with essential hypertension, who had studies of their renin-aldosterone system performed between April 1967 and December 1972, were surveyed for myocardial infraction or cerebrovascular accident. Of the patients, 42% had low plasma renin activity. Myocardial infractions or cerebrovascular accidents were documented in 15% of those with low plasms renin activity and in 5% of those with normal plasma renin activity. When adjustments were made for differences in afe and blood pressure , a protective effect in low-renin hypertension was evident. When black patients were considered separately,there was no difference in diastolic blood pressure; however, vascular complications were not less frequent in low-renin hypertensives. The results suggest that low plasma renin activity does not protect against the development of vascular complications in essential hypertension.

Black People↗
PubMed1975

The presence of histone H1degree in human tissues.

Histone Hidegree was found to be present in a number of human tissues. It constituted 50% of the total 5% perchloric acid-soluble histone in human breast, 35%in thyroid, 12 to 18% in adrenal, and 7% in parathyroid tissues. The quantities of histone Hldegree in these human tissues were large compared with the amounts found in rat liver (8%), calf thymus (0%), and HeLa cells (0%). Although the quantity of histone Hldegree was found to vary from one type of tissue to another, it was essentially constant in normal, hyperplastic, and neoplastic human thyroid tissues.

Adrenal Glands↗
PubMedDate not supplied

Serum immunoglobulins in hypertension.

We measured serum immunoglobulins in 52 persons whose blood pressure was higher than 140/90 mm Hg, and 52 normotensive controls matched for age, sex and race. All were selected from a population of actively employed persons undergoing a routine health evaluation. Contrary to previous reports, the hypertensive subjects did not have higher levels of IgG or IgA than the controls. Sixteen hypertensive subjects with mean blood pressure higher than 115 mm Hg did not have elevated IgG or IgA levels when analyzed separately. Serum IgM was significantly lower in the 52 hypertensive subjects (125 +/- 67 mg/dl vs 171 +/- 85 mg/dl, p less than 0.01). Our subjects failed to show the increase in immunoglobulins reported by others. The most likely reasons for this is the mildness of their blood pressure elevation, although the absence of immunoglobulin elevation in the small number with more marked hypertension does not support this explanation.

Adult↗