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O Clark

Publications and source records attributed to O Clark.

4 recordsLinked to original sources
PubMed1992

Set-point for parathyroid hormone release increases with postmaturational aging in the rat.

The plasma concentration of immunoreactive PTH (iPTH) increases with postmaturational aging in both humans and animals. In the present study we determined the basal, maximally stimulated, and maximally suppressed levels of iPTH and the concentration of whole blood ionized calcium sufficient to produce half-maximal suppression of the plasma concentration of iPTH (set-point for PTH release) in male Fischer 344 rats aged 3, 6, 12, 18, 24, and 28 months. Basal iPTH increased 2.3-fold from 3 to 28 months of age, whereas basal blood ionized calcium remained unchanged. The set-point for PTH release increased steadily and significantly (P < 0.001) from 1.19 +/- 0.09 mM at 3 months to 1.37 +/- 0.13 mM at 24 months and then declined slightly to 1.32 +/- 0.11 mM at 28 months of age. Basal iPTH correlated significantly with set-point. Neither maximally stimulated nor maximally suppressed iPTH levels showed any significant change with advancing age. These results suggest that the age-related increase in basal plasma iPTH in the rat may be in part a consequence of an increase in the set-point for PTH release.

Aging↗
PubMed1984

A new method with high sensitivity and specificity for localization of abnormal parathyroid glands.

A novel method for localization of abnormal parathyroid glands involving color-processing of nuclear scintigrams of the neck after injection of Thallium-201 and Technetium pertechnetate is presented with surgical correlation. Preoperative localization of single parathyroid adenomas was successful in 88% of previously unoperated patients and in 85.7% of those with adenomas not located at previous surgery. Eighty-three per cent of glands with secondary hyperplasia, 66% of glands with primary hyperplasia, and one carcinoma were localized. No abnormal studies were seen in non-hyperparathyroid hypercalcemia, and no false positive studies were seen. Localization appeared related to larger adenomas (300-5000 mg), although one of 60 mg was localized. Color-comparison dual-isotype scintigraphy was useful for localization of parathyroid adenomas and hyperplastic glands and exceeded the reported sensitivity of either ultrasonography or computerized tomography. It deserves wider evaluation in preoperative management of at least hyperparathyroidism of the primary or persistent types.

Adenoma↗
PubMed1982

Successful treatment of adrenal metastases from large-cell carcinoma of the lung.

Although on a weight basis the adrenal gland is the most common site of extranodal spread from lung cancer, antemortem diagnosis and successful therapy of adrenal metastasis are rare. We have treated two patients with apparently solitary metastases in the adrenal gland from large-cell carcinomas of the lung using a combination of adrenalectomy and vigorous therapy to the primary site. Both patients experienced symptomatic relief, and, in contrast to the expected short survival in lung cancer with distant metastasis, they remain well six years and 14 years after treatment.

Adrenal Gland Neoplasms↗