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Biomedical subjects

E Paloyan

Publications and source records attributed to E Paloyan.

At least 73 records · Page 4Linked to original sources
PubMed1983

Effects of radiation on parafollicular C cells of the thyroid gland.

While radiation has well-recognized effects on follicular cells of the thyroid gland, those on parafollicular C cells are not yet established. Low-dose radiation that has been proved to be nonablative and carcinogenic to follicular cells was administered to 8-week-old Long-Evans rats to study the changes in C cell number and function. Circulating calcitonin levels were significantly reduced in animals that had undergone radiation at age 24 months. Mean calcitonin values were 0.66 (+/- 0.20) ng/ml and 1.64 (+/- 0.59) ng/ml for control males and females compared with 0.14 (+/- 0.06) ng/ml and 0.11 (+/- 0.01) ng/ml for males (P less than 0.05) and females (P less than 0.001) that had undergone radiation, respectively. These levels correlated well with C cell population density in thyroid glands in the control group and in the group that had undergone radiation as evidenced by light microscopy. Routine hematoxylin and eosin staining showed C cell hyperplasia in 77% of control animals of both sexes compared with 4% in animals that had undergone radiation (P less than 0.005). Immunoperoxidase staining with an anticalcitonin antibody showed virtual absence of C cells in most animals that had undergone radiation compared with diffusely scattered cells in animals in the control group. Medullary carcinomas occurred in 14% of animals in the control group compared with 3% of animals that had undergone radiation (P less than 0.05). These data indicate that the radiation dosage that is carcinogenic to the follicular epithelium causes lethal injury to C cells and thus suggest that C cells are more sensitive to radiation than are follicular cells. This increased sensitivity could explain the virtual absence of C cells, decrease in calcitonin levels, and reduced numbers of medullary carcinomas in the animals that had undergone radiation.

Animals↗
PubMed1983

Successful autotransplantation of parathyroid adenomas in seven patients.

The autotransplantation of normal as well as adenomatous parathyroid tissue is currently being used with increasing frequency. In the present report, we describe our experiences with the successful transplantation of adenomatous or hyperplastic parathyroid tissue in seven patients. Prior to transplant surgery, six of these patients had recurrent or persistent primary hyperparathyroidism. The last patient was on hemodialysis for chronic renal failure and was presumed to have tertiary hyperparathyroidism. A large superior mediastinal parathyroid adenoma was found at a second neck exploration. In all patients, the only remaining parathyroid tissue was either adenomatous or hyperplastic. A total of 30 to 75 mg of this parathyroid tissue was diced and transplanted into single subfascial pockets of the forearm muscles (6) or sternocleidomastoid muscle (1). Following transplantation, all patients required transient calcium and vitamin D supplements for six to 12 weeks. In follow-up studies of ten months to 12 years, all patients have remained eucalcemic with normal parathyroid hormone levels. The use of a single subfascial pocket (versus the popular method of multiple implants) may explain the lack of recurrent hyperparathyroidism in our small population.

Adenoma↗
PubMed1982

Incidental asymptomatic adrenal masses detected by computed tomographic scanning. Is operation required?

Until recently, adrenal masses came to clinical attention either from local symptoms due to massive enlargement or from manifestations of excess hormones production. During the last year, an adrenal mass was identified as an incidental finding in nine patients undergoing abdominal computed tomographic (CT) scanning for unrelated problems. These five men and four women ranged in age from 41 to 73 years. Eight were hypertensive. After the CT scan, each was evaluated for catecholamine or steroid hypersecretion. Only one had clearly elevated urinary vanillylmandelic acid, metanephrine, and catecholamine levels. Equivocal evidence of catecholamine excess was seen in five patients who had slight elevation of one urinary metabolite or of plasma epinephrine or norepinephrine levels. Three patients had no evidence of medullary or cortical hyperfunction on repeated testing. Eight patients were good operative risks and underwent unilateral adrenalectomy without complication. Masses ranging in size from 1 to 4 cm were found in each. These included four cortical adenomas, two adrenal cysts, one adrenal lipoma, and one pheochromocytoma. The pheochromocytoma occurred in the patient with strong biochemical evidence of disease. With wider application of CT imaging, increasing numbers of asymptomatic adrenal masses will be detected. Care in interpreting the clinical significance of these masses and caution in recommending treatment are required.

Adenoma↗
PubMed1982

Prior irradiation and the development of coexistent differentiated thyroid cancer and hyperparathyroidism.

Twelve patients with coexistent well-differentiated thyroid carcinoma and primary hyperparathyoidism were studied to determine the frequency of previous radiation exposure. Eight were found to have received prior irradiation. External radiation was administered to the head and neck region for benign conditions such as tonsillar enlargement, acne, scrofula, and thyroid enlargement. One patient received 131I therapy for carcinoma of the thyroid. The observation that 67% of the patients in this series had previous radiation to the head and neck strongly implicates radiation exposure in the development of coexistent well-differentiated thyroid carcinoma and hyperparathyroidism.

Adult↗
PubMed1982

Simultaneous primary hyperparathyroidism and nodular thyroid disease.

Of 351 patients treated for primary hyperparathyroidism from 1966 to 1981, 70 (20%) had grossly evident nodular thyroid disease at the time of subtotal parathyroidectomy. These patients have been reviewed to determine if prior radiation exposure may play a role in their coexistence and if combined subtotal parathyroidectomy and thyroidectomy are safe and efficacious. Thirty-three of the 70 patients (47%) had received prior radiation therapy for benign conditions of the head and neck. Nine of 15 patients with nonmedullary thyroid carcinoma had received previous irradiation. In addition to subtotal parathyroidectomy, 28 patients underwent total thyroidectomy, 14 underwent bilateral subtotal thyroidectomy, and 28 underwent unilateral lobectomy. There were no deaths and no permanent recurrent laryngeal nerve injury from combined subtotal parathyroidectomy and thyroidectomy. Two patients in whom parathyroid tissue was not autotransplanted required calcium and vitamin D supplementation. This study shows that (1) primary hyperparathyroidism and nodular thyroid disease occur simultaneously with sufficient frequency to warrant careful preoperative and intraoperative evaluation of both glands, (2) radiation probably does play a role in the pathogenesis of coexistent primary hyperparathyroidism and nodular thyroid disease, and (3) in experienced hands combined subtotal parathyroidectomy and thyroidectomy can be safely performed.

Adenoma↗
PubMed1982

Pancreatitis associated with primary hyperparathyroidism.

Two series of patients treated for primary hyperparathyroidism are reviewed for the incidence of associated pancreatitis. In an earlier series of 150 hyperparathyroid patients, six had documented pancreatitis as one of the primary clinical manifestations. Review of a more recent series failed to uncover a single case of pancreatitis in 26 patients with primary hyperparathyroidism. The incidence of pancreatitis associated with hyperparathyroidism appears to be steadily decreasing, possibly reflecting the earlier diagnosis of parathyroid disease, which is due to widespread screening testing methods currently available.

Adult↗
PubMed1982

Castration induces a marked reduction in the incidence of thyroid cancers.

Although thyroid disease in humans predominates in females, the prognosis of thyroid cancer in males is much less favorable. To further explore the role of male sex hormones, we utilized the experimental model of radiation-induced follicular cancer in the rat, studying the effects of castration on tumor development. Microscopic evidence of tumor formation was correlated with the biochemical parameters serum thyroxine (T4), thyrotropin (TSH), and thyrocalcitonin (TC) at 24 months. The incidence of follicular carcinomas in intact males ws 58%, compared to 28% in comparable females. Castration of males caused a reduction in the incidence to 22%. Mean circulating levels of TSH were markedly elevated in all three irradiated groups. Mean T4 levels were reduced significantly only in irradiated castrated animals. TC levels were reduced in all irradiated groups. We conclude that although elevated levels of TSH probably play a significant role in the development of radioactive iodine-triggered follicular thyroid neoplasms in the rat, male sex hormone may also play an important role beyond their known effect on basal and thyrotropin-releasing hormone-stimulated TSH.

Adenocarcinoma↗
PubMed1981

Subtotal parathyroidectomy: normalization of circulating parathormone.

Subtotal parathyroidectomy was performed in 52 consecutive patients with primary hyperparathyroidism. The postoperative results, 6-24 months following the operation, were evaluated according to a calcium-parathormone normogram. In 48 patients the values returned to the normal zone. Two patients had persistent hypercalcemia. The other two patients remained in the hyperparathyroid zone of the normogram, with moderate elevations of serum parathormone, in spite of normocalcemia. The significance of the failure to achieve normal circulating parathormone levels in patients with postoperative eucalcemia is discussed. The importance of serum parathormone and calcium relationship in the evaluation of patients following parathyroidectomy is emphasized.

Calcium↗
PubMed1981

Unexpected parathyroid disease discovered at thyroidectomy in irradiated patients.

Eight of 23 patients undergoing total thyroidectomy for radiation-associated nodular thyroid disease were found to have unsuspected parathyroid hyperplasia or adenoma at operation. The total serum calcium level was normal preoperatively in each patient. Serum ionized calcium and parathyroid hormone levels were measured in five patients preoperatively and were normal in each case. These pathologic findings in normocalcemic patients may represent a preclinical form of hyperparathyroidism, which would be further evidence linking radiation to the pathogenesis of hyperparathyroidism. The parathyroid glands should be evaluated both pre-operatively and at operation in all patients who have a history of radiation and require thyroidectomy.

Adenoma↗
PubMed1981

Hyperparathyroid crisis. Successful treatment of ten comatose patients.

Hyperparathyroid crisis is a rare disease manifested by elevated serum calcium, weakness, nausea and vomiting, altered states of consciousness, and elevated circulating parathormone. This hypercalcemic state is noted for a frequently acute presentation and associated high mortality rate, approaching 60% in some series. Ten patients in parathyroid crisis were observed in a consecutive personal series of 325 cases of operatively proved hyperparthyroidism. All 10 patients were successfully treated. Each patient remained or lapsed into persistent coma despite extensive medical management and normalization of serum calcium in some instances. An emergency parathyroidectomy was performed in all cases. Reversal of the comatose state was noted in all patients within 24 hours, followed by gradual normalization of serum calcium. Serum calcium ranged from 15 to 19.6 mg/dl. The blood urea nitrogen level was elevated in six patients. A single adenoma was found in nine patients and multiglandular disease involving the neck and the mediastinum in one. All patients survived. The successful treatment of this disease demands prompt and accurate diagnosis coupled with vigorous medical therapy and emergency parathyroidectomy if the patient's status continues to deteriorate.

Acute Disease↗
PubMed1979

The continued importance of adrenalectomy in the treatment of Cushing's disease.

Eighteen patients with pituitary-dependent Cushing's disease have been treated during a ten-year period. Eleven of these received a total of 14 alternative forms of therapy in an attempt to control the clinical manifestations of Cushing's disease prior to adrenalectomy. However, no substantial improvement was noted in these patients, who included four receiving conventional pituitary irradiation, five receiving cyproheptadine, two receiving mitotane, and one each receiving metyrapone and phenytoin. One patient had an attempted transsphenoidal hypophysectomy that could not be accomplished because of hemorrhage. A complete remission of the signs, symptoms, and laboratory abnormalities of Cushing's disease occurred in all 18 patients following bilateral adrenalectomy. There was no operative mortality and morbidity was minimal. This experience confirms that bilateral adrenalectomy is a rapid, safe, and permanent means of reversing hypercortisolism and that it should remain an integral part of the treatment of Cushing's disease.

Adolescent↗