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Biomedical subjects

P H Forsham

Publications and source records attributed to P H Forsham.

At least 19 recordsLinked to original sources
PubMed1979

Feedback-controlled dextrose infusion during surgical management of insulinomas.

Through the use of a feedback-controlled dextrose infusion system, we obtained continuous monitoring of the blood glucose level in a patient undergoing surgery for multiple pancreatic beta-cell tumors. In addition, this device infused dextrose at variable rates to maintain a predetermined euglycemic level of 90 mg/dl. Before locating the source of excessive insulin production, the maximum dextrose infusion rate of 400 mg/min was required; but after extirpation of multiple insulinomas, the dextrose-infusion rate declined whereas the blood glucose level rose above the preselected level. These results emphasize the usefulness of a monitoring and infusion system not only in protecting the patient from the hazard of hypoglycemia under anesthesia but also as an aid in determining whether all insulin-secreting tumors have been removed.

Adenoma, Islet Cell↗
PubMed1979

Diabetic management by insulin infusion during major surgery.

In five insulin-requiring, uremic diabetic patients undergoing renal transplantation, we infused insulin intravenously at a low rate to maintain plasma glucose levels between 100 and 200 mg/100 ml. In those patients receiving 100 mg or more of prednisone per day and 5 per cent dextrose solution, the hourly infusion rate was determined from tthe following equation: insulin (U) = plasma glucose value divided by 100. When prednisone was not given or when the patient was thin, the ratio became: plasma glucose value divided by 150. Results were compared with those of nineteen similar transplant patients treated with conventional subcutaneous insulin therapy during surgery, and significantly better glucose control was achieved with the low dosage, intravenous infusion.

Adult↗
PubMed1979

Dopamine during alpha- or beta-adrenergic blockade in man. Hormonal, metabolic, and cardiovascular effects.

We studied the contribution of alpha- and beta-adrenergic receptor activation to the cardiovascular, metabolic, and hormonal effects of dopamine. At a concentration of 1.5 mug/kg.min, the infusion of dopamine in 12 normal volunteers was associated with a transient but significant rise in pulse rate, which was prevented by propranolol. Venous plasma glucose did not change throughout the experiments, and a mild increase in plasma free fatty acid levels observed during the administration of dopamine alone was antagonized by propranolol. In contrast, neither the beta-adrenergic blocker, propranolol, nor the alpha-adrenergic blocker, phentolamine, was effective in inhibiting the dopamine-induced rise in plasma glucagon (from 82+/-9 to 128+/-14 pg/ml; P < 0.005) and serum insulin (from 7.5+/-1 to 13+/-1.5 muU/ml; P < 0.005) or its suppression of plasma prolactin (from 8.5+/-1 to 5.2+/-0.8 ng/ml; P < 0.001). Although serum growth hormone levels did not change during the infusion of dopamine alone, an obvious rise occurred in three subjects during the combined infusion of propranolol and dopamine. Whereas some metabolic and cardiovascular effects of dopamine are mediated through adrenergic mechanisms, these observations indicate that this is not the case for the effects of this catecholamine on glucagon, insulin, and prolactin secretion, and thus provide further support for the theory of a specific dopaminergic sensitivity of these hormonal systems in man.

Adrenergic alpha-Antagonists↗
PubMed1979

Phentolamine and the action of somatostatin in man.

The inhibition by somatostatin (SRIF) of basal and arginine-stimulated glucagon, insulin, and glucose levels was compared with that obtained when SRIF was preceded by alpha-adrenergic blockade with phentolamine. No noteworthy differences were observed, except that the characteristic rebound of insulin upon discontinuation of SRIF was significantly lower with phentolamine (P less than 0.01). These results indicate that inhibition of basal and arginine-stimulated glucagon and insulin secretion by SRIF in man is not mediated through activation by alpha-adrenergic receptors.

Adult↗
PubMed1979

Variation in thickness of the capillary basement membrane in single muscles of diabetic subjects.

Thickness of skeletal muscle's capillary basement membrane was measured in gastrocnemius and quadriceps femoris muscles of diabetic subjects. At least two different sites of each muscle studied were biopsied. Comparison of these biopsy samples revealed a marked and significant variation in thickness of the capillary basement membrane at different sites within the same muscle. In one subject so studied, this variation was found regardless of the method of fixation or the method of measurement of capillary basement membrane thickness used. Variation was present in diabetics suffering from long-term complications of the disease as well as in diabetics free of such complications. A reevaluation of the biologic significance of basement membrane thickness measurements, as presently applied, is indicated in the light of the variability of base-line values.

Adult↗
PubMed1979

Prolactin-secreting pituitary adenomas in multiple endocrine adenomatosis, type I.

In three unrelated families, four patients with multiple endocrine adenomatosis, type I, had confirmed or highly probable prolactin-secreting pituitary adenomas. In one patient, selective transsphenoidal tumor resection resulted in normal prolactin levels and resumption of menses. Heretofore, the majority of pituitary tumors in such patients had been thought to be nonsecreting chromophobe adenomas, but recent studies have shown that, in sporadic cases, as many as three fourths of "nonsecreting" pituitary tumors in fact secrete prolactin. Thus, based on our experience and reports of others, we believe that prolactin-secreting tumors may be common in patients with pituitary tumors as part of the syndrome of multiple endocrine adenomatosis, type I, and we recommend that serum prolactin be measured when evaluating these patients and their families.

Adult↗
PubMed1978

Cushing's disease. Selective trans-sphenoidal resection of pituitary microadenomas.

We undertook trans-sphenoidal microsurgical pituitary exploration in 20 consecutive patients with Cushing's disease, eight of whom had normal sellar polytomography. Pituitary adenomas were selectively resected in 17 and histologically confirmed in 14. In one patient total hypophysectomy revealed a 1.5-mm basophilic adenoma, and in two patients vascular anomalies prevented sellar exploration. Hypercortisolism was corrected in 17 patients (i.e., in 16 of the 17 undergoing selective tumor removal and in the one with total hypophysectomy). Panhypopituitarism occurred only in this patient, and transient diabetes insipidus occurred in five. Most patients became glucocorticoid deficient and required replacement therapy. We conclude that pituitary tumors are present in the great majority of patient with Cushing's disease, even in the absence of demonstrable tomographic changes in the sella turcica, and that selective removal corrects hypercortisolism with little morbidity.

Adenoma↗
PubMed1978

Comparison of absorption of cortisone acetate and hydrocortisone hemisuccinate.

In four patients who required maintenance glucocorticoid therapy after bilateral adrenalectomy for Cushing's disease, we compared the effects of im injection and oral ingestion of cortisone acetate and hydrocortisone hemisuccinate. By the former route of administration, cortisone acetate was not effective in elevating plasma cortisol levels or in suppressing plasma adrenocorticotropin, although hydrocortisone was. When given by mouth, no significant difference was found between the two steroids. Therefore, in the treatment of acute adrenal insufficiency or in the maintenance of patients with chronic adrenal insufficiency and in their preparation for surgery or other stressful situations, we advise against im injection of cortisone acetate. Oral ingestion, however, is appropriate for maintenance.

Absorption↗
PubMed1978

Intrasellar cysticercosis presenting as a pituitary tumor: successful transsphenoidal cystectomy with preservation of pituitary function.

A 42-year-old woman from El Salvador presented with arthralgias and headache. She was found to have an enlarged sella with an intrasellar mass. Transsphenoidal exploration of the sella revealed a cysticercus. The cyst was removed and normal pituitary function was retained. Review of the literature showed three previously reported confirmed or suspected cases of intrasellar cysticercosis: in two, the diagnosis was made at autopsy; in the third, a patient with hypopituitarism, intrasellar cysticercosis was suspected in life but never confirmed histologically. Transsphenoidal cystectomy successfully treated our patient without compromise of pituitary function and is recommended for similar cases.

Adult↗
PubMed1977

Cushing's disease: growth hormone response to hypoglycemia after correction of hypercortisolism.

Growth hormone responses to insulin-induced hypoglycemia were studied in 17 patients with inactive Cushing's disease. A normal GH rise was found in 9 of 9 patients without evidence of progressive pituitary tumor after bilateral adrenalectomy and 3 of 4 patients after correction of hypercortisolism by transsphenoidal removal of pituitary microadenomas. In contrast, 3 of 4 patients with Nelson's syndrome had impaired GH responsiveness to hypoglycemia. These results show that GH responsiveness is normal in the majority of patients with inactive Cushing's disease and do not support the concept of a primary hypothalamic or central nervous system abnormality of GH regulation in Cushing's disease.

Adrenalectomy↗
PubMed1977

Differential effects of L-dopa and apomorphine on glucagon secretion in man: evidence against central dopaminergic stimulation of glucagon.

In 6 normal subjects, L-dopa (500 mg PO) and apomorphine (0.6 mg sc) increased circulating growth hormone and suppressed prolactin levels in a parallel and quantitatively similar fashion, but only L-dopa induced a rise in plasma glucagon, glucose, and insulin levels. The failure of apomorphine to affect glucagon secretion, despite a substantial effect on growth hormone and prolactin, was also observed in insulin-dependent diabetics known to exhibit A-cell hyperresponsiveness to various stimuli. In view of the highly dissimilar molecular and pharmacologic characteristics of L-dopa and apomorphine, these data do not exclude a local dopaminergic effect of L-dopa at the pancreatic level, but strongly militate against a central dopaminergic pathway for glucagon stimulation.

Adult↗
PubMed1977

Plasma cyclic nucleotide levels in juvenile-onset diabetes.

In patients with juvenile-onset diabetes, plasma concentrations of 3',5'-adenosine cyclic monophosphate (cAMP) were significantly lower than those of norman subjects [16 +/- 4 and 24 +/- 7 pmol per milliliter (p less than 0.025), respectively] as determined in this laboratory; whereas there were essentially no differences in plasma levels of 3',5'-guanosine cyclic monophosphate (cGMP). Because cAMP inhibits cell growth and cGMP stimulates it, these findings may represent an important factor in the atherosclerotic and obliterative angiopathies of diabetic individuals. We observed that cyclic nucleotide values were the same whether or not the subjects were receiving insulin. Those given insulin plus enough glucose to maintain hyperglycemia revealed modest elevations in cyclic nucleotide levels. Thus, the ratio of cAMP to cGMP, abnormally low in juvenile-onset diabetes, is relatively independent of short-term variations in plasma levels of either glucose of insulin.

Adult↗
PubMed1976

Role of glucagon in human diabetic ketoacidosis: studies using somatostatin.

The present studies demonstrate that endogenous glucagon is hyperglycaemic, lipolytic and ketogenic in man, and that insulin deficiency is necessary, but is in itself not sufficient, to cause fulminant diabetic ketoacidosis. Furthermore, continuous elevation of endogenous glucagon secretion appears to be necessary for the maintenance and continued development of the characteristic metabolic consequences of insulin lack.

Adult↗
PubMed1976

Effects of physiologic levels of glucagon and growth hormone on human carbohydrate and lipid metabolism. Studies involving administration of exogenous hormone during suppression of endogenous hormone secretion with somatostatin.

To study the individual effects of glucagon and growth hormone on human carbohydrate and lipid metabolism, endogenous secretion of both hormones was simultaneously suppressed with somatostatin and physiologic circulating levels of one or the other hormone were reproduced by exogenous infusion. The interaction of these hormones with insulin was evaluated by performing these studies in juvenile-onset, insulin-deficient diabetic subjects both during infusion of insulin and after its withdrawal. Infusion of glucagon (1 ng/kg-min) during suppression of its endogenous secretion with somatostatin produced circulating hormone levels of approximately 200 pg/ml. When glucagon was infused along with insulin, plasma glucose levels rose from 94 +/- 8 to 126 +/- 12 mg/100 ml over 1 h (P less than 0.01); growth hormone, beta-hydroxy-butyrate, alanine, FFA, and glycerol levels did not change. When insulin was withdrawn, plasma glucose, beta-hydroxybutyrate, FFA, and glycerol all rose to higher levels (P less than 0.01) than those observed under similar conditions when somatostatin alone had been infused to suppress glucagon secretion. Thus, under appropriate conditions, physiologic levels of glucagon can stimulate lipolysis and cause hyperketonemia and hyperglycemia in man; insulin antagonizes the lipolytic and ketogenic effects of glucagon more effectively than the hyperglycemic effect. Infusion of growth hormone (1 mug/kg-h) during suppression of its endogenous secretion with somastostatin produced circulating hormone levels of approximately 6 ng/ml. When growth hormone was administered along with insulin, no effects were observed. After insulin was withdrawn, plasma beta-hydroxybutyrate, glycerol, and FFA all rose to higher levels (P less than 0.01) than those observed during infusion of somatostatin alone when growth hormone secretion was suppressed; no difference in plasma glucose, alanine, and glucagon levels was evident. Thus, under appropriate conditions, physiologic levels of growth hormone can augment lipolysis and ketonemia in man, but these actions are ordinarily not apparent in the presence of physiologic levels of insulin.

Adult↗