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Biomedical subjects

D M Raybin

Publications and source records attributed to D M Raybin.

4 recordsLinked to original sources
PubMed1987

Adaptations of neurotransmitter synthesis to chronic hypoxia in cell culture.

Tyrosine hydroxylase and tryptophan hydroxylase are widely held to be rate-limiting for the synthesis of the catecholamines and serotonin, respectively. Both enzymes are oxygen-requiring and kinetic properties suggest that oxygen availability may limit synthesis of these neurotransmitters in the brain. Using pheochromocytoma cells as a cell culture model for catecholamine synthesis, and neuroblastoma cells as a model for serotonin synthesis, enzyme activity was measured under control and hypoxic conditions. Both tyrosine hydroxylase and tryptophan hydroxylase activity increased substantially with chronic exposure but not with acute exposure. In the case of tyrosine hydroxylase, increased enzyme content with hypoxia accounts for increased activity. This suggests a mechanism for the maintenance of neurotransmitter synthesis with chronic hypoxia. Measurement of intracellular metabolites revealed no change in dopamine or norepinephrine in hypoxic pheochromocytoma cells, consistent with a simple adaptive mechanism. However, in neuroblastoma cells, hypoxia was associated with an increase in serotonin concentration. The reasons for this are still unclear.

Animals↗
PubMed1985

Successful treatment of pulmonary lymphangiomyomatosis with oophorectomy and progesterone.

A 35-yr-old woman, with profound dyspnea at rest and failure to thrive, asked to be evaluated at Stanford Medical Center. She requested a second opinion after entering death counseling in another institution because of an unrelenting, deteriorating course caused by pulmonary lymphangiomyomatosis. Her recurring right chylous pleural effusion was drained by chest tube, a LaVeen shunt was placed to decompress her severe chylous ascites, an oophorectomy was performed, large dose progesterone (medroxyprogesterone acetate) was initiated intramuscularly, and during her hospitalization she was fed by total parenteral nutrition. She was discharged mildly improved after 2 months. Now, 3 yr later, her pulmonary function tests and chest radiographs are improved, and she walks 2 miles per day and teaches school full time. Extensive hormonal analysis did not reveal an endocrinologic abnormality that could explain the pathophysiology of her disease. However, the patient had multiple human chorionic gonadotropin injections before becoming ill, as have a number of other patients who have developed this disease. This report is an example of successful treatment of severe pulmonary lymphangiomyomatosis.

Adult↗