The lung-associated peptide calcitonin (CT) has been localized by immunocytochemical means to discrete pulmonary endocrine (PE) cells. A long-term cell culture of CT-staining PE cells has been established. The molecular configuration of immunoreactive (iCT) from PE cell extracts was determined by gel chromatography, revealing predominantly large molecular weight forms of iCT. The size distribution characteristics of PE Cell iCT were similar to those of intact hamster lung. In contrast, hamster thyroid extracts contain predominantly 4000 dalton iCT (presumed monomer) and apparent iCT fragments. The culture media of the PE cells were found to contain mainly 4000 dalton iCT. We conclude that although the predominant forms of iCT found within cultured PE cells are distinct from those found within thyroidal C-cells, both iCT producing cells release mainly the monomer into the media. Malignant human bronchial carcinoid cells store predominantly monomeric iCT while secreting large molecular weight forms of iCT. Since the PE cell is the putative precursor cell to neuroendocrine malignancies, the disparity noted in the processing of CT may have significant pathobiological implications.

Animals↗

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Calcitonin levels in thyroid-vein blood of man.

Radioimmunoassay determinations of calcitonin from blood samples obtained by selective venous catheterization have demonstrated a large peripheral to thyroid vein gradient for this hormone in both normocalcemic and hypercalcemic persons. These fingings indicate that in fasting humans the thyroid gland maintains peripheral levels of calcitonin by actively secreting the hormone, and are consistent with the suggestion that the role of plasma calcitonin is of physiologic significance.

Adult↗

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Calcitonin in thyroidectomized patients.

Hypothyroid patients with total or near-total thyroidectomy were found to have detectable immunoreactive calcitonin in the serum and urine. These findings suggest that human calcitonin may be secreted by extrathyroidal tissues.

Adult↗

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Limited calcitonin reserve in hyperparathyroidism.

A comparative study was made of the serum calcitonin levels of patients with hyperparathyroidism. The mean serum calcitonin of those with hyperparathyroidism did not differ significantly from normal persons (mean +/- SEM: 130 +/- 16 pg/ml vs 124 +/- 7 pg/ml, respectively.) Only 0.5% of patients with hyperparathyroidism had values exceeding the upper limits of normal. In contrast, the mean serum calcitonin of patients with hypercalcemia of nonparathyroid etiology was considerably higher than normal (354 +/- 75 pg/ml, p < 0.001)), and 41% exceeded the upper limits of normal. Calcium infusion induced less of an increase in serum calcitonin for patients with hyperparathyroidism than for normal persons. In addition, the diminished responsibility was also present postoperatively. These findings suggest that the prolonged hypercalcemia associated with hyperparathyroidism results in a decreased calcitonin reserve which may persist for unknown reasons. In the clinical evaluation of hypercalcemic patient, the finding of hypercalcitonemia is suggestive evidence against the diagnosis of hyperparathyroidism.

Calcitonin↗

PubMedDate not supplied

Serum calcitonin may be a marker for inhalation injury in burns.

One of the principal causes of death from burns is inhalation injury. The pulmonary neuroendocrine cell contains and secretes immunoreactive calcitonin (iCT), and, under the influence of various irritative stimuli, can be induced to secrete iCT in excess. A prospective study of serum iCT levels in 41 patients with burns was undertaken. Mean serum iCT levels were four times normal values at the time of admission and reached 31 times normal values by 24 hours after injury. These levels did not correlate specifically with burn size. However, serum iCT had a very strong positive correlation with mortality, and in addition, was highest in patients who died early after injury compared with those who died late after injury. Patients who were clinically suspected to have pulmonary injury and who died had markedly higher levels of iCT than those who survived. In addition, serum iCT correlated positively with the need for mechanical ventilation and the amount of pulmonary shunting. Although other factors may also play a role in hypercalcitoninemia, serum iCT may be an important marker for the presence of inhalation injury, as well as a prognostic indicator.

Adult↗

PubMedDate not supplied

Cholinergic regulation of hamster pulmonary neuroendocrine cell calcitonin.

The lung content of the peptide hormone calcitonin (iCT) has been localized to discrete and clustered pulmonary neuroendocrine cells. We have undertaken a study of the effect of the autonomic ganglionic agent nicotine on the iCT of hamster lung. The acute subcutaneous administration of nicotine raised serum iCT, while lung tissue concentration of the hormone changed reciprocally to that of the serum. One week following right-sided vagotomy, total (left plus right side) iCT levels decreased following nicotine; the concentration of iCT on the denervated right lung was more markedly decreased than that from the left lung. Hamster serum levels of iCT were significantly reduced following thyroid ablation. As in the intact animals, the subsequent subcutaneous injection of nicotine to these animals raised serum iCT. Further pharmacological evaluations revealed that subcutaneously administered nicotinic cholinergic antagonists, but not muscarinic cholinergic antagonists, prevented the nicotine-evoked increase in serum iCT. Furthermore, the subcutaneous injection of acetylcholine was found to mimic the effect noted for nicotine; this was also abolished by prior administration of a nicotinic antagonist, but not by a muscarinic antagonist. The present study suggests that the nicotinic effect on pulmonary iCT secretion is ganglionically mediated, presumably via vagal innervation of the pulmonary neuroendocrine cells.

Animals↗

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HIV counseling, testing, and prevention in primary care.

Human immunodeficiency virus (HIV) continues to be the second leading cause of death for persons ages 25 to 44 years in the United States, whereas new HIV infection rates remain steady. Coupled with the advent of new antiviral therapies that have significantly decreased mortality and morbidity rates, the importance of the primary care clinician in HIV prevention, early detection, and treatment is paramount. This article presents HIV risk analysis and prevention strategies for the primary care clinician practice. New HIV testing methods are reviewed as well as the Centers for Disease Control (CDC) pretest and posttest counseling guidelines.

AIDS Serodiagnosis↗

PubMedDate not supplied

Young woman with recurrent yeast infections.

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AIDS-Related Opportunistic Infections↗

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Women and substance use disorders.

In the United States, 45% of all women use alcohol, and nearly 26% smoke cigarettes. Approximately 13% use illicit substances, prescribed medications, or both in recreational ways. Although women use these substances less often than men, the health consequences of their use for women, particularly the use of alcohol, are either equivalent or greater. Women's social relationships play key roles in the onset of substance use disorders, treatment, and continued recovery. Major psychoactive substances include nicotine, alcohol, illicit drugs, and recreational use of nonprescribed medications. Biopsychosocial aspects unique to women are reviewed, followed by treatment approaches, concluding with implications for primary care providers.

Female↗

PubMedDate not supplied

The inter-relationship between vertebral fractures and osteoporosis.

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Absorptiometry, Photon↗

PubMedDate not supplied

Breast self-exam.

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Breast Self-Examination↗