Search PubMed⌕ Search

Biomedical subjects

J R Minkoff

Publications and source records attributed to J R Minkoff.

8 recordsLinked to original sources
PubMed1987

Age-related rise in parathyroid hormone in man: the use of intact and midmolecule antisera to distinguish hormone secretion from retention.

Circulating levels of parathyroid hormone (PTH) rise with age in normal men and women. To resolve the basis for this observation we measured iPTH in 137 normal men and women, age 23 to 85 years, using two antisera which responded to different portions of the PTH molecule. A midmolecule assay (Mid-PTH) employed antiserum NG-5, which recognizes mid- and carboxy-terminal portions of hPTH, whereas antiserum CK-67, which recognizes determinants in the 1-34 hPTH sequence, was used to measure intact PTH (NH2-PTH). Two-hour fasting urine was collected for measurement of creatinine clearance and excretion indices of phosphorus and cyclic AMP. Serum was analyzed for 25-hydroxyvitamin D (25-OHD) in addition to iPTH. Mid-PTH rose significantly with age in the 72 women (r = 0.38, p less than 0.001) and in the 65 men (r = 0.40, p less than 0.001). NH2-PTH rose with age in women (r = 0.23, p less than 0.05), but a change in men was not significant (r = 0.19, n.s.). Cyclic AMP excretion rose significantly with age in both women (r = 0.42) and men (r = 0.41), whereas phosphorus excretion rose significantly in women only (r = 0.32, p less than 0.01). 25-OHD levels were 27.5 +/- 1.3 ng/ml for women and 26.1 +/- 1.2 ng/ml for men. No change in 25-OHD was observed with age in women, and a significant decrease in men was due entirely to extremely high values in three young subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Interactions of medroxyprogesterone acetate with estrogen on the calcium-parathyroid axis in post-menopausal women.

We studied the effect of medroxyprogesterone acetate (MPA) as a single agent and in combination with conjugated equine estrogens (E), on the calcium-parathyroid axis in healthy post-menopausal women. Twenty-six subjects, 2-22 yr post-menopause, were studied under basal conditions, and then following 10 days of MPA (10 mg/day), 30 days of E (0.625 or 1.25 mg/day), and an additional 10 days of E + MPA. As predicted, E decreased urinary excretion of calcium and hydroxyproline. MPA did not alter these excretion variables, either when given alone, or when added to E. Cyclic administration of MPA for 10 days is currently advocated to avoid the adverse endometrial consequences of unopposed estrogen. These data indicate that such a program does not interfere with the beneficial effect of estrogen on the calcium-parathyroid axis.

Adult↗
PubMed1985

Plasma cyclic AMP response to calcitonin: a potential clinical marker of bone turnover.

A noninvasive marker of bone turnover would be useful in predicting which patients are at risk of rapid bone loss and in monitoring response to therapy. Calcitonin (CT)-induced hypocalcemia correlates with bone turnover but has not been a clinically useful test because changes in serum calcium are small, and test duration is long. CT rapidly increases plasma cAMP levels. We conducted studies in rats and in man to characterize the origin of this rise, and to determine its suitability as a potential clinical marker of bone resorption. Administration of CT to rats resulted in a prompt and sustained rise in plasma cAMP. This effect was not blunted by nephrectomy and was greater in calcium-deprived rats with increased bone resorption. Thus, it appears to reflect CT action on bone. An intramuscular injection of 100 units salmon CT elevated plasma cAMP in 18 normal men and women. This effect was observed by 20 min after injection and persisted over 2 h. Although basal levels of plasma cAMP were similar in healthy postmenopausal women and men, the response to CT was greater in women. The response of women with hyperparathyroidism was greater than that of normal women, and the response of pagetic men was greater than that of normal men. The rise in plasma cAMP following CT is rapid and easily measured and appears to correlate with the state of bone remodeling. Additional studies will be required in osteoporotic subjects with high and low remodeling activity before the clinical utility of this test can be determined.

Aged↗
PubMed1984

Acromegaly and Zollinger-Ellison syndrome secondary to an islet cell tumor: characterization and quantification of plasma and tumor human growth hormone-releasing factor.

A young woman with acromegaly and Zollinger-Ellison syndrome associated with a GH-releasing factor (GRF)- and gastrin-secreting metastatic islet cell carcinoma was studied by means of specific antisera which recognize various regions of the GRF molecule. Using specific immunohistochemical techniques, the tumor cells were shown to contain GRF, gastrin, and gastrin-releasing peptide, but not GH. During a 4-h period, plasma GRF levels averaged 5.6 +/- 1.4 ng/ml (+/- SD), while GH levels averaged 148 +/- 71 ng/ml. GH secretion was pulsatile and increased after TRH administration. GRF RIAs may be useful in establishing the diagnosis of acromegaly secondary to the ectopic secretion of GRF.

Acromegaly↗