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Biomedical subjects

W B Malarkey

Publications and source records attributed to W B Malarkey.

At least 91 records · Page 5Linked to original sources
PubMed1982

Evidence that chorion-decidual prolactin release is calcium dependent.

The regulation of PRL release from chorion-decidual explants was evaluated in organ cultures. Agents previously shown to stimulate pituitary release in vitro (TRH, theophylline, estradiol, and vasoactive intestinal polypeptide) were all without effect on chorion-decidual PRL release. Media free of calcium, however, resulted in 44% decreased chorion-decidual PRL release. Conversely, 2.5 mM CaCl2 produced a 64% increase in PRL release (P less than 0.01). Also, calcium chelation with EGTA (0.125-1.0 mM) produced a dose-related decrease in chorion-decidual PRL release. This decrease was greatest at 1.0 mM (P less than 0.01), being 56% of control. In contrast, the calcium-calmodulin complex inhibitor trifluoperazine (10 micrometers) did not significantly alter chorion-decidual PRL release. These studies and previous report in the literature suggest that different control mechanisms govern pituitary and chorion-decidual PRL release; however, an exception appears to be a common role for calcium.

Calcium↗
PubMed1982

Sleep and growth hormone secretion in alcoholics.

The effect of alcoholism on slow wave sleep (SWS) and SWS-related human growth hormone (HGH) secretion was investigated in 8 sober male alcoholics and 13 non-alcoholic controls. Sleep onset was temporally correlated with both elevated HGH levels and a high percentage of SWS in control subjects, with several specific qualifications related to age. By contrast, alcoholism was associated with a dissociation of sleep onset, SWS, and HGH elevation. The first noticeable HGH elevation in sober alcoholics often occurred several hours after sleep onset and in the absence of any SWS in the same time interval. Acute intoxication appeared to "normalize" the sleep onset-SWS linkage in alcoholics but did not influence the dissociation of HGH elevation from sleep onset and SWS.

Adult↗
PubMed1981

Thyrotoxicosis and a thyrotropin-secreting pituitary tumor causing unilateral exophthalmos.

Hyperthyroidism due to a TSH-secreting pituitary tumor has been noted by a number of investigators. We describe a unique case in which a 17-yr-old female presented with clinical hyperthyroidism, a goiter, and unilateral exophthalmos. Serum T4, free T4, and T3 (RIA) were consistently elevated along with elevated TSH levels (range, 10-100 microunits/ml). Skull x-rays and computed tomography scan revealed a tumor invading the right orbit. Other pituitary function studies were normal and LATs was undetectable. Surgery performed resulted in 70% removal of the pituitary tumor and confirmed the presence of tumor infiltration into the right orbit. TRH tests done pre- and postoperatively (patient still clinically hyperthyroid with elevated T4 and TSH levels) showed TSH and PRL responsiveness. Electron microscopy of the tumor demonstrated features typical of pituitary thyrotrophs. Monolayer cultures of pituitary cells released TSH over time into the media but did not respond to TRH stimulation. Pituitary adenoma tissue content of immunoreactive TSH was 65 microunits/g wet tissue and demonstrated immunosimilarity with human standard. We conclude that the patient had a TSH-secreting pituitary tumor responsive to TRH stimulation.

Adenoma, Chromophobe↗
PubMed1980

Diurnal variation of prolactin secretion differentiates pituitary tumors from the primary empty sella syndrome.

In an attempt to find an endocrine function test that might be useful in differentiating the primary empty sella syndrome from a pituitary tumor, we evaluated 24-hour prolactin levels in seven patients with the primary empty sella syndrome, 16 patients with pituitary tumors and 37 normal subjects. All eight patients with the primary empty sella syndrome had normal 24-hour mean prolactin levels and normal diurnal variation of prolactin release whereas in each patient with a pituitary tumor nocturnal prolactin secretion was blunted. In light of these findings and those of other investigators, we do not perform routine invasive study of the pituitary in patients with (1) a typical clinical presentation of the empty sella syndrome, (2) no endocrinopathies, (3) a normal computerized axial tomography scan, when indicated, and (4) normal serum prolactin levels with intact diurnal variation.

Adolescent↗
PubMed1979

Disordered growth hormone and prolactin secretion in primary disorders of sleep.

Growth hormone (GH) and prolactin (PR) secretion were evaluated in 28 patients who had sleep apnea or narcolepsy but no other primary neurologic or endocrine disorders. Eighty-one percent of subjects with impaired alertness failed to demonstrate serum GH concentrations in excess of 5 ng per milliliter following oral administration of L-DOPA, 500 mg. Diminished GH responses to sleep and intravenous arginine were observed in 57 percent and 44 percent, respectively, of patients tested. Sleep-related PRL release was less than normal in women with narcolepsy, with or without sleep apnea. All patients had at least one abnormality in GH or PRL secretion.

Adult↗
PubMed1977

Leukocytosis and artifactual hypoglycemia.

Two patients are described with asymptomatic low blood glucose and excessive in vitro consumption of glucose by leukocytes before separation of the serum for assay. This may be a more common problem than is appreciated and need not be associated with leukemia or extreme leukocytosis. The circumstances that allow this avoidable type of artifactual hypoglycemia may also produce factitious euglycemia during evaluation of suspected diabetes mellitus.

Blood Glucose↗
PubMed1977

Acute pancreatitis secondary to furosemide with associated hyperlipidemia.

A patient is described with acute pancreatitis which was probably caused by furosemide. Administration of furosemide on two separate occasions was associated with increases in serum amylase concentrations and recurrence of abdominal pain. This case is of further interest because of the presence of hyperlipemia in the absence of an underlying lipid abnormality. Following recovery from pancreatitis, the lipoprotein pattern evolved from type V to type III, type IIA, and finally to normal.

Acute Disease↗
PubMed1977

Disordered nocturnal prolactin regulation in women with breast cancer.

Mean 24-hr prolactin concentrations were determined in 25 female control subjects, 16 women with benign breast masses, and 23 subjects with breast cancer. This evaluation performed before breast surgery revealed significantly decreased (p less than 0.02) nocturnal (12 a.m. to 7 a.m.) prolactin concentrations in 12 postmenopausal breast cancer subjects that contrasted with significantly increased (p less than 0.05) nocturnal prolactin levels in five luteal-phase premenopausal women with breast cancers. Prolactin concentrations in patients with benign breast disease were not significantly different from control subjects. Two of the premenopausal breast cancer patients had marked preoperative elevations in their mean 24-hr prolactin levels, and they were two of the three subjects who have since expired. Nocturnal prolactin secretion was significantly decreased (p less than 0.03) in four premenopausal breast cancer patients when they were studied 1 year after surgery; however, it remained the same in the eight postmenopausal breast cancer patients similarly evaluated. Although disordered prolactin regulation has been found in these women with breast cancer, its role in the etiology and progression of human cancer is still uncertain.

Adult↗