Search PubMed⌕ Search

Biomedical subjects

O H Clark

Publications and source records attributed to O H Clark.

At least 235 records · Page 13Linked to original sources
PubMed1978

Iodine deficiency produces hypercalcemia and hypercalcitonemia in rats.

To determine the effect of thyroid-stimulating hormone (TSH) on secretion of calcitonin by the thyroid, 50 male Sprague-Dawley rats were randomly separated into seven groups. The groups received different diets, medications, or operations [propylthiouracil (PTU), iodine-deficient diet, (LID), acute or chronic thyroxine treatment, sham operation (SO), hemithyroidectomy (Htx), and total thyroidectomy (Ttx)]. two weeks to six months later, serum TSH concentrations were increased in the Htx, Ttx, and LID groups when compared with SO animals. Serum calcitonin concentrations were increased in the LID- and PTU-treated groups and were decreased in animals that chronically received thyroxine. Serum calcium concentrations were increased in the LID animals, decreased in the Ttx animals, and were similar in the other groups. These findings suggest that TSH stimulates both follicular and parafollicular cells in the rat thyroid and that iodine deficiency causes hypercalcemia and hypercalcitonemia.

Animals↗
PubMed1976

Management of thyroid nodules in the elderly.

Eleven malignant thyroid tumors were found in 100 consecutive patients more than sixty years old having thyroid operations. Based on preoperative findings, these 100 patients could be separated into two groups according to high and low risk for malignancy. Clinical manifestations in the high risk group were presence of a discrete cold thyroid nodule, hoarseness, dysphagia, an enlarging mass, or palpable ipsilateral cervical adenopathy; and in the low risk group, asymptomatic multinodular goiter, diffusely enlarged glands with elevated antithyroid antibody titers, and a family history of goiter. All eleven patients with malignant thyroid tumors were found in the sixty-six patients considered at high risk, whereas no malignant lesions were found in the low risk patients. Six of the malignant thyroid tumors were undifferentiated and in three of these a thyroid nodule had been present for more than fifteen years. There were no operative deaths and only one significant complication, a recurrent laryngeal nerve injury. Thyroidectomy is indicated for elderly patients with thyroid nudules who have features of the high risk group, whereas patients in the low risk group can be safely followed.

Age Factors↗
PubMed1976

Recurrent hyperparathyroidism.

Recurrent hyperparathyroidism occurred in 11 of 295 patients from 10 months to 34 years after an initially successful operation. Seven patients with recurrent hyperparathyroidism had either multiple endocrine adenomatosis type I (MEA) or familial hyperparathyroidism (FHP), one patient had parathyroid cancer, and two patients had renal failure at the time of recurrence. Four of these patients ahd their initial operations elsewhere. Recurrence developed in 33% of patients with MEA or FHP but in only 0.4% of 242 patients without MEA or FHP. The presence of MEA or FHP was known before parathyroid exploration in 18 (86%) of the 21 patients. In patients with MEA or FHP, subtotal parathyroidectomy should be performed if there is more than one gland involved. Other patients should be treated by selective removal of an adenoma because recurrence is rare. Subtotal parathyroidectomy should be reserved for patients with diffuse hyperplasia.

Adenoma↗
PubMed1976

Compensatory thyroid hypertrophy after hemithyroidectomy in rats.

Thyroid enlargement occurs in association with a variety of circumstances characterized by an impaired capacity of the gland to secrete adequate amounts of hormone. To elucidate the factors responsible for such compensatory thyroid growth, particularly the role of TSH, we have observed the response of the serum TSH, T3 and T4 concentrations following hemithyroidectomy in the rat, and have attempted to correlate changes in these functions with changes in the weight and histology of the thyroid remnant. Hemithyroidectomy was performed in male Sprague-Dawley rats weighing 150 to 370 g, sham-operated animals serving as controls. As compared to findings in sham-operated animals, serum T4 concentrations declined promptly after hemithyroidectomy. In Experiment I serum T4 concentrations remained low for about 10 days and then returned to initial values. In Experiment II serum T4 concentrations remained lower than initial T4 values or values found in sham-operated animals until 34 days after hemithyroidectomy. Serum T3 concentrations were not significantly altered after hemithyroidectomy in either group but tended to be lower in the hemithyroidectomized animals. Serum TSH concentrations increased within 3 days after hemithyroidectomy and, for as long as 21 weeks, remained at values higher than those present preoperatively or those seen in sham-operated animals. Thyroid lobe weight increased following removal of the contralateral lobe and this increase was also sustained throughout the duration of the experiments. Biochemical and histological observations indicated that enlargement of the residual lobe was due to hypertrophy rather than hyperplasia.

Animals↗
PubMed1975

Postoperative adrenal hemorrhage.

Twelve elderly patients without Waterhouse-Friderichsen syndrome or adrenal tumor who had spontaneous adrenal hemorrhage one to 33 days after operation are described. Seven of these patients had operations on the gastrointestinal tract, one on the biliary system, two on the genitourinary system and two on the central nervous system. Important factors relating to adrenal hemorrhage included: intra-abdominal sepsis in 5 patients, cancer in 4, pneumonia in 4, coagulation defects in 2, exogenous steroids in 2, and syphilis in one patient. Spontaneous adrenal hemorrhage should be considered in patients whose condition deteriorates rapidly after operation and in whom no other explanation is plausible. Its detection and appropriate therapy can be lifesaving.

Adrenal Gland Diseases↗
PubMed1975

Spontaneous delayed splenic rupture--case report of a five-year interval between trauma and diagnosis.

A 27-year-old white man was admitted in shock with a tender distended abdomen 5 years following significant thoraco-abdominal trauma. Immediately following resuscitation he had an emergency exploratory laparotomy because of his critical condition. At operation 3 liters of old and fresh blood were present intraperitoneally and the spleen was ruptured. The spleen was surrounded by and adherent to the omentum and adjacent viscera. Splenectomy was performed and recovery was uneventful. Histologic examination of the spleen confirmed the 5-year interval between injury and rupture. Delayed splenic rupture accounts for 14% of all splenic injuries and has a high mortality. This case represents the longest reported delay between splenic trauma and delayed rupture.

Adult↗
PubMedDate not supplied

Thyroid mass.

In addition to the history given in this case the consultants ask for information regarding a family history of thyroid cancer or exposure to irradiation. An FNA is in order all the time (Dr. Fredrickson), only if there is no history of irradiation (Dr. Clark), and repeatedly if the mass is cystic (Dr. Harvey). All concur with thyroid suppression if the FNA and thyroid scan support a benign diagnosis. With an FNA report of a "follicular neoplasm" the consultants state that the pathologist should narrow down the histology further. But coupled with the cold nodule on thyroid scan, a lobectomy is in order. All would proceed with a lobectomy and rely on frozen section before going further. If the mass is malignant on frozen section a completion total thyroidectomy is in order. With a frozen section report of papillary follicular carcinoma all agree that a total thyroidectomy is in order. The management of the lymph nodes varies with removal of the ipsilateral lymph nodes (Dr. Clark), bilateral paratracheal lymph node dissection (Dr. Fredrickson), or a sampling of adjacent lymph nodes including those in the mediastinum (Dr. Harvey). A neck dissection is in order only if some of the lymph nodes are positive for tumor. Two experts (Drs. Clark and Harvey) are never comfortable losing a parathyroid gland. If one is found it should be autotransplanted into the sternocleidomastoid muscle (Dr. Clark) or the brachioradialis (Dr. Harvey). While every attempt should be made to identify and preserve all the parathyroid glands another expert believes that one parathyroid gland is probably enough to sustain normal hormone levels (Dr. Fredrickson).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMedDate not supplied

Persistent/recurrent hyperparathyroidism: a comparison of sestamibi scintigraphy, MRI, and ultrasonography.

For patients with persistent or recurrent hyperparathyroidism, parathyroid imaging is indicated to confirm the presence of abnormal parathyroid gland(s) and identify their location. These imaging techniques are being modified constantly and newer methods have been developed. Sestamibi scintigraphy, MRI and sonography were compared in 23 patients with persistent or recurrent hyperparathyroidism. Preoperative 99m-Technetium Sestamibi (MIBI), MRI and ultrasonographic (US) studies of 23 patients with 25 histopathologically confirmed abnormal parathyroid glands were compared, using independent prospective interpretations. All patients had been operated upon previously for hyperparthytroidism. Accuracy of various combinations of MRI, MIBI, and US also were calculated. The results are shown for all abnormal glands (n =25); sensitivities and accuracies were 88 and 84% for MRI, 80 and 80% for MIBI, and 58 and 44% for US. For only parathyroid adenomas (n = 18), sensitivities and accuracies were 89 and 89% for MRI, 94 and 94% for MIBI, and 58 and 39% for US. Finally, for parathyroid hyperplasia (n = 7 glands in five patients), sensitivities and accuracies were 83 and 71% for MRI, 43 and 43% for MIBI, and 57 and 57% for US. Either MIBI or MRI results were significantly better for detecting abnormal parathyroid glands than US (P < 0.01), but MRI and MIBI were not statistically different. Combining MRI and MIBI produced a combined accuracy of 92%, whereas combining either of these tests with US did not improve on the accuracy of either test alone. In conclusion, for patients with persistent or recurrent hyperparathyroidism, MRI and MIBI are equally accurate for detecting abnormal parathyroid glands, and the combination of both tests may be more accurate than either test alone.

Adenoma↗