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Biomedical subjects

J M Feldman

Publications and source records attributed to J M Feldman.

At least 55 records · Page 3Linked to original sources
PubMed1987

An unusual pheochromocytoma associated with an androgen secreting adrenocortical adenoma. Evaluation of its polypeptide hormone, catecholamine, and enzyme characteristics.

Our patient had a left suprarenal mass. His blood pressure was normal, but his urinary catecholamines (CA), vanillylmandelic acid (VMA), total metanephrines (TMn) and 5-hydroxyindolacetic acid (5HIAA) were elevated. In addition, he had elevated, nonsuppressible urinary 17-ketosteroids (17KS) and androsterone, but his urinary 17-hydroxycorticoids (17OHCS) and free cortisol were normal, as were his plasma cortisol and ACTH. After resection of the suprarenal mass, the patient's urinary hormone values reverted to normal. The mass contained a pheochromocytoma and an adrenocortical adenoma. The pheochromocytoma was unusual in that it contained very little norepinephrine (NE) and dopamine (DA) and an abundance of epinephrine (E) despite normal enzyme concentrations. Electron micrographs showed primarily E granules with few of the NE-type. The immunoperoxidase histochemical stains for vasoactive intestinal peptide (VIP) and serotonin (S) were strongly positive. The patient's blood pressure may have been normal because his pheochromocytoma secreted E, VIP, or S. The associated adrenocortical adenoma produced no symptoms and was probably coincidental.

Adenoma↗
PubMed1987

Falsely elevated urinary excretion of catecholamines and metanephrines in patients receiving labetalol therapy.

Five patients with essential hypertension who were receiving treatment with the beta- and alpha-adrenoreceptor-blocking drug labetalol had elevated urinary excretion of catecholamines. When measured with a radioenzymatic assay, all five subjects had elevated urinary excretion of norepinephrine and normal urinary excretion of epinephrine; when measured with a fluorometric assay, four subjects had elevated urinary excretion of epinephrine with normal urinary excretion of norepinephrine, and one subject had elevated urinary norepinephrine excretion with normal urinary excretion of epinephrine. In three subjects who could be reevaluated three days to two months after labetalol therapy was discontinued, the urinary catecholamine levels had returned toward normal. Our studies indicate that labetalol produced a false elevation of urinary catecholamine levels. Although labetalol also interfered with the measurement of urinary excretion of metanephrine, it did not interfere with the measurement of urinary excretion of vanillylmandelic acid, homovanillic acid, 5-hydroxyindoleacetic acid, and serotonin, and it probably did not interfere with the measurement of plasma concentrations of dopamine, norepinephrine, and epinephrine. We conclude that labetalol therapy should be discontinued, and another beta-blocking drug, such as propranolol, that does not interfere with these tests should be temporarily substituted at least three days before a patient collects a 24-hour urine for measurement of the urinary excretion of catecholamines and metanephrine.

Adult↗
PubMed1987

Carcinoid liver metastases. Accuracy of radionuclide liver/spleen imaging compared to computed tomography.

Carcinoid liver metastases may be more easily detected by radionuclide liver-spleen studies (RN imaging study) than by computed tomography (CT). While multiple studies have suggested that CT is a more sensitive test than the Tc-99m sulfur colloid study for the detection of most types of liver metastases, carcinoid tumors appear to be an exception. The results of 23 pairs of CT and RN imaging studies that were obtained within one month of each other in patients with proven carcinoid tumors are reported. Comparison of the initial reports of the studies as well as a blinded reinterpretation of the studies suggest that in this group of patients the RN imaging study appeared to be superior to CT in the evaluation of the response to therapy.

Carcinoid Tumor↗
PubMed1987

Carcinoid and other metabolically active tumors in the elderly.

This article reviews the clinical manifestations, diagnostic techniques, and therapy of carcinoid and other metabolically active tumors that occur in the elderly. These tumors secrete monoamine and polypeptide hormones into the vascular compartment. Because these hormones may produce symptoms early in the course of the illness and are amenable to measurement, physicians have the opportunity to make a prompt diagnosis.

Aged↗
PubMed1986

Role of neuropeptides and serotonin in the diagnosis of carcinoid tumors.

The plasma concentrations of neuropeptides (neurotensin, substance P, motilin, somatostatin, vasoactive intestinal peptide and gastrin-releasing peptide), the urinary excretion of 5-hydroxyindoleacetic acid and serotonin, and the platelet concentration of serotonin were compared in 133 patients who could be assigned to one of four groups. These groups were as follows: carcinoid tumors present; history of carcinoid tumors; miscellaneous tumors present; and non-tumor diseases. The test with the most sensitivity (i.e., patients with carcinoid tumors labeled positive) and the test with the most specificity (i.e., patients without carcinoid tumors labeled negative) for the presence of carcinoid tumors was determined. Urinary 5-hydroxyindoleacetic acid excretion had a sensitivity of 73 percent and a specificity of 100 percent; the plasma concentration of substance P had a sensitivity of 32 percent and a specificity of 85 percent; and the plasma concentration of neurotensin had a sensitivity of 41 percent and a specificity of 60 percent. Even when basal plasma concentrations of substance P and neurotensin were elevated, there was no additional increase of these neuropeptides prior to ethanol-induced facial flushing. Although measurements of plasma neuropeptide levels may be helpful in occasional patients with carcinoid tumors, it is concluded that measurements of serotonin overproduction--such as 5-hydroxyindoleacetic acid excretion--are of more general value.

Adult↗
PubMed1986

Flushing in the carcinoid syndrome and plasma kallikrein.

To examine the role of kallikrein in the etiology of flushing in the carcinoid syndrome, chromogenic substrates specific for kallikrein were used to measure two isoenzymes of this substance. The plasma and glandular kallikrein levels were determined in 20 carcinoid patients and in 17 controls. Kallikrein levels were not significantly different between these two groups. Twelve carcinoid patients and six controls were given alcohol and the kallikrein activity was measured before and at 2, 5, and 10 minutes after alcohol ingestion; kallikrein activity did not change significantly. Kallikrein was absent from the primary tumors of seven patients with carcinoids. These studies, therefore, indicate that kallikrein with subsequent induction of bradykinin formation is not solely responsible for the flushing in the carcinoid syndrome.

Adult↗
PubMed1986

Urinary serotonin in the diagnosis of carcinoid tumors.

To determine whether measurement of serotonin in urine would give useful complementary information to the usual measurement of 5-hydroxyindoleacetic acid (5-HIAA) in urine and platelet serotonin in platelets, I measured these analytes in 75 consecutive patients with carcinoid tumors, and found that 75% had above-normal urinary 5-HIAA excretion, 64% had above-normal serotonin excretion, and 64% had above-normal platelet serotonin concentration. Six patients had increased urinary serotonin, but 5-HIAA excretion and platelet serotonin concentration were normal. Only two of a further 50 patients with solid noncarcinoid tumors--and none of 55 patients with flushing or diarrhea, who did not prove to have a carcinoid tumor--had increased urinary serotonin. Ingestion of four bananas (a food rich in serotonin) increased urinary 5-HIAA but not urinary serotonin excretion of seven normal subjects. Evidently, measurement of urinary serotonin excretion is helpful in the evaluation of patients with suspected carcinoid tumors.

Adult↗
PubMed1986

Iodine-131 metaiodobenzylguanidine scintigraphy of carcinoid tumors.

Iodine-131 metaiodobenzylguanidine ([131I]MIBG) is concentrated in pheochromocytomas and can be detected by external imaging. We administered [131I]MIBG to 23 patients with carcinoid tumors to determine if it would be useful in scanning patients with these tumors. The carcinoid tumors of 14 of the 23 patients (61%) were visualized. Iodine-131 MIBG was concentrated most avidly by tumors of midgut origin (ileum, cecum); it was concentrated less avidly by some tumors of foregut origin (pancreas, stomach); it was not significantly concentrated by other tumors of foregut origin (bronchus). We conclude that 131I is a useful imaging agent for carcinoid tumors.

3-Iodobenzylguanidine↗
PubMed1985

Monoamine and diamine oxidase activity in the diagnosis of carcinoid tumors.

This study determines if one could distinguish foregut from midgut carcinoid tumors by quantitative measurement of the monoamine oxidase (MAO) and diamine oxidase (DAO) activities in homogenates of tumors. The MAO activity of 16 foregut carcinoid tumors (1850 +/- 342 pmol/mg/minute) was significantly higher than the MAO activity of 11 midgut carcinoid tumors (407 +/- 43 pmol/mg/minute, P less than 0.01) with no overlap between the groups. Although all ten of the midgut carcinoids had measurable DAO activity (720 +/- 190 pmol/mg/minute), with the exception of one duodenal carcinoid tumor (33 pmol/mg/minute) the nine foregut carcinoid tumors evaluated did not have detectable DAO activity. The MAO activity of all of the foregut carcinoids was higher than that of 6 islet cell tumors, 28 paragangliomas, and 12 medullary carcinomas of the thyroid. Quantitative MAO and DAO activity may be useful in distinguishing foregut carcinoid tumors from other related tumors.

Amine Oxidase (Copper-Containing)↗
PubMed1985

Review of glyburide after one year on the market.

After one year on the American market, glyburide, a second-generation sulfonylurea, seems well accepted by physicians. If the hyperglycemia of patients with type II diabetes mellitus is not corrected by diet and exercise, glyburide can be used as adjunctive therapy. The drug is comparable in efficacy to the first-generation sulfonylurea chlorpropamide, but it has fewer reported side effects. Additionally, glyburide does not appear to interact with other medications and is well absorbed from the gastrointestinal tract. Although the drug had been reported to produce hypoglycemia, increased clinical experience--along with use of judicious dosages in appropriate patients--has decreased the incidence of hypoglycemia. Although still in the investigational stage, combination insulin/glyburide therapy may also benefit subgroups of type II diabetic patients. Glyburide is a useful and rational addition to therapy in properly selected patients with type II diabetes mellitus.

Chlorpropamide↗
PubMed1985

Effect of estradiol-17 beta on glucose and proline uptake in plasma membrane vesicles from the R3230AC rat mammary carcinoma.

Purified plasma membrane vesicles isolated from R3230AC rat mammary tumors displayed carrier-mediated and stereospecific uptake. Uptake was shown to be proportional to protein concentration, sensitive to increasing osmolarity, and inhibited only by substrates entering by the same carrier. Carrier-mediated glucose uptake was inhibited rapidly by estradiol-17 beta and phloretin in a dose-dependent manner, whereas proline uptake was not affected by estradiol-17 beta. The data suggest that the inhibition of glucose by estradiol and phloretin, originally observed in whole cells, occurs by an interaction of the steroid with a component on the plasma membrane. In contrast, the lack of effects of estradiol on proline transport into vesicles implies that intracellular components may have mediated the estrogen-induced effects observed in whole cells.

3-O-Methylglucose↗
PubMed1985

Adult respiratory distress syndrome in a pregnant patient with a pheochromocytoma.

Five weeks after developing spells of shortness of breath, headache, weakness and abdominal pain, a 29-year-old woman, who was in the 36th week of her third pregnancy developed adult respiratory distress syndrome (ARDS). Although the ARDS resolved after a cesarean section, her infant died at birth. Her "spells" continued until a left pheochromocytoma was diagnosed and resected 2 years later. If there are no other known inciting causes of ARDS in a pregnant patient, a pheochromocytoma should be ruled out with appropriate catecholamine determinations.

Adrenal Gland Neoplasms↗
PubMed1985

Increased dopamine production in patients with carcinoid tumors.

Although both carcinoid tumors and pheochromocytomas arise from neural crest origin, they are thought to each secrete distinctive monoamines; carcinoid tumors, which contain tryptophan hydroxylase, secrete serotonin, and pheochromocytomas, which contain tyrosine hydroxylase, may secrete dopamine (DA), norepinephrine (NE), or epinephrine (E). The purpose of this study was to determine if patients with carcinoid tumors have evidence of increased DA production. Of patients with serotonin-producing carcinoid tumors, 18%, 27%, and 35%, respectively, had increased urinary homovanillic acid (HVA) excretion (the principal metabolite of DA), urinary DA excretion, and plasma DA concentration. In contrast, none of the patients with nonserotonin-producing carcinoid tumors had evidence of increased DA production. Only 4% of patients with miscellaneous tumors had increased excretion of homovanillic acid or DA; none of the patients with miscellaneous tumors had increased plasma DA concentration. This study suggests that DA and HVA measurements may be useful in the evaluation of some patients with suspected carcinoid tumors.

Adult↗