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Biomedical subjects

L Benson

Publications and source records attributed to L Benson.

At least 91 records · Page 5Linked to original sources
PubMed1987

Hyperparathyroidism presenting as the first lesion in multiple endocrine neoplasia type 1.

In a study of 16 different families, 55 persons were considered to be affected by the syndrome of multiple endocrine neoplasia type 1 (MEN-1). Serum calcium measurements were available for all but six patients, long deceased, and hypercalcemia was invariably present. All but four of these patients have been subjected to surgery, and hyperparathyroidism was verified in each case. In all the patients studied, hyperparathyroidism was apparently the first manifestation of the MEN-1 syndrome. Pituitary tumors were detected in 23 patients, and there was evidence of pancreatic lesions in 32. Although either the pituitary or pancreatic manifestations dominated clinically in some patients, hyperparathyroidism was invariably present when sought. Measurement of serum calcium in asymptomatic relatives at risk for MEN-1 disclosed no case of hyperparathyroidism in children below the age of 18, whereas half of all screened persons between the ages of 18 and 30 were found to have hyperparathyroidism. In some, the serum calcium values were only marginally or even intermittently elevated. It is concluded that since hyperparathyroidism is apparently the first lesion in MEN-1, screening for this syndrome should primarily be directed toward the diagnosis of hyperparathyroidism. The temporal relationships suggest that hyperparathyroidism could be a prerequisite for the other types of endocrine neoplasms in the MEN-1 syndrome.

Adolescent↗
PubMed1987

Clodronate treatment in patients with malignancy-associated hypercalcemia.

The possibility of reducing symptomatic hypercalcemia and of maintaining total serum calcium concentrations less than 2.8 mmol/l with clodronate (dichloromethylene bisphosphonate) was evaluated in 28 patients with various types of malignant tumors. Four episodes of hypercalcemic crisis with mean serum calcium concentrations of 4.43 mmol/l were controlled within 4-6 days of intravenous clodronate (4 mg/kg BW/day). This was accompanied by a moderate increase in serum creatinine values which, however, returned to pretreatment levels after therapy withdrawal in all but one case. Oral clodronate successfully reduced a mean serum calcium concentration of 3.16 mmol/l in 22 out of 25 patients after 3-12 days (800-3,200 mg/day). After reversal of the hypercalcemias oral clodronate controlled the serum calcium concentration for up to 42 weeks in six out of 15 patients After discontinuation of initial therapy five of seven recurrent hypercalcemias were successfully treated with oral or intravenous clodronate. Hypocalcemia and subjective side-effects were uncommon. It is concluded that clodronate is a valuable clinical tool in the management of patients with malignancy-associated hypercalcemia.

Administration, Oral↗
PubMed1987

Dynamic tests of parathyroid function for diagnosis of primary hyperparathyroidism in malignancy.

Hypercalcaemia can be caused by malignant diseases as well as by primary hyperparathyroidism (HPT). The two disorders may occur together and an accurate discrimination between them is sometimes not possible from basal measurements of calcium and parathyroid hormone (PTH) concentrations. In primary HPT the regulation of PTH secretion is maintained, albeit the set-point is shifted to a hypercalcaemic value. Therefore, when serum calcium is lowered by ethylene diamine tetra-acetic acid (EDTA) infusions or calcitonin injections, patients with primary HPT display enhanced secretion of PTH already within the hypercalcaemic range, whereas parathyroid function remains suppressed in malignancy-associated hypercalcaemia. Tests based on this principle enable a specific identification of HPT. The present report describes eight hypercalcaemic patients with disseminated malignancy where HPT could be diagnosed by the use of such stimulatory tests.

Adenoma↗
PubMed1987

A standardized meal stimulation test of the endocrine pancreas for early detection of pancreatic endocrine tumors in multiple endocrine neoplasia type 1 syndrome: five years experience.

Forty-nine members of 6 families with multiple endocrine neoplasia type 1 (MEN 1) were investigated with a standardized meal stimulation test to detect the presence of pancreatic endocrine tumors. Fifteen age-matched subjects and 4 patients with primary hyperparathyroidism also were studied. Serum pancreatic polypeptide (PP), gastrin, and insulin as well as plasma glucagon and somatostatin concentrations were determined before and during the test meal. Patients with demonstrable pancreatic endocrine tumors had significantly increased mean basal and peak serum PP (P less than 0.001) and gastrin (P less than 0.001) responses to the meal compared with healthy family members and normal subjects. Seven of 12 MEN 1 patients with parathyroid and pituitary disease but no demonstrable pancreatic endocrine tumors had exaggerated PP and/or gastrin responses to the meal; 4 of them developed pancreatic endocrine tumors, detected by abdominal computerized tomography, 0.5-4 yr later. None of the healthy members of the MEN 1 families or the patients with primary hyperparathyroidism had responses different from those of the normal subjects. Our experience with the meal stimulation test indicates that an elevated basal or exaggerated serum PP and/or gastrin response is an earlier sign of pancreatic involvement in the MEN 1 trait than is abdominal computerized tomography.

Adenoma, Islet Cell↗
PubMed1987

Parathyroid hormone release in vitro in hyperparathyroidism associated with multiple endocrine neoplasia type 1.

Hyperparathyroidism (HPT) in the syndrome of multiple endocrine neoplasia type 1 (MEN-1) exhibits a different picture regarding its propensity for recurrence compared with sporadic primary HPT. In order to shed further light on the MEN-1 syndrome an investigation in vitro was made of parathyroid hormone (PTH) release of dispersed parathyroid cell from 11 patients with parathyroid hyperplasia associated with MEN-1, 10 patients with single parathyroid adenomas, and 10 preparations of normal bovine parathyroid glands. The two patient groups had the same average serum calcium value prior to surgery. Immunoreactive concentrations of PTH were measured after 2-h incubations at extracellular calcium concentrations of 0.5-3.0 mmol/l. Compared with the normal bovine parathyroid cells, the cells of the MEN-1 patients had a reduced calcium sensitivity of the PTH release and secreted smaller amounts of hormone at both low and high extracellular calcium concentrations. A similar abnormality of the PTH release was found for the cells of the hyperplastic and adenomatous parathyroid glands. Although individual parathyroid glands were investigated in only three MEN-1 patients, the results suggested the secretory regulation to be less defective in the small glands of each patient. It is concluded that in patient groups matched for serum calcium, the parathyroid tissue of MEN-1 patients has an abnormality of the PTH release similar to that of parathyroid adenomas.

Adenoma↗
PubMed1987

Optimal discrimination of mild hyperparathyroidism with total serum calcium, ionized calcium and parathyroid hormone measurements.

The serum concentrations of calcium, albumin and parathyroid hormone (PTH) and the plasma levels of ionized calcium were determined in 124 healthy subjects, 89 patients with primary hyperparathyroidism (HPT), 23 of whom had the syndrome of multiple endocrine neoplasia type 1 (MEN-1) and 43 patients who had hypercalcaemia of other causes than HPT (non-HPT), in most cases due to widespread malignancies. The total serum calcium was corrected for the serum albumin concentration (CaM). Healthy females over the age of 50 had higher CaM, than younger females and the women of all ages also had, higher serum PTH levels than males. For all study groups both the intra- and inter-diurnal variations were small for all the studied variables. Discriminant function and optimal discriminatory limits were calculated with the help of computer programs. A consideration of all the individuals in the discriminant analysis, revealed that measurements of CaM alone separated most HPT patients both from the healthy subjects and from the non-HPT patients. However, when only those who had borderline values (defined as CaM between 2.45 and 2.75 mmol/l) were included it turned out that measurements of ionized calcium markedly improved the delineation of mild HPT from the healthy subjects and that, in addition, PTH measurements helped to exclude those with non-HPT hypercalcaemia. The optimal discriminatory levels of serum calcium were calculated as the levels which caused the minimum loss in terms of misclassification when attention was paid to the relative importance of false positive to false negative classifications and to the prevalence of HPT. The optimal discriminatory level for serum calcium for a weighting ratio between false positive to false negative of 1:1, and a prevalence of HPT of 1%, was calculated to be 2.68 mmol/l and for a prevalence of 50% 2.56 mmol/l. In the latter situation a weighting ratio of 10:1 for false positive to false negative gave a level of 2.63 mmol/l while a weighting ratio of 1:10 corresponded to an optimal discriminatory level of 2.47 mmol/l.

Adolescent↗
PubMed1986

Evaluation of noninvasive measurements of oxygenation in stable infants.

The accuracy with which transcutaneous measurements of oxygen tension reflect PaO2 in older infants has recently been questioned. We therefore examined the effect of maturation, i.e., age or skinfold thickness, on the accuracy of transcutaneous oxygen tension (PtcO2) and oxygen saturation (StcO2) measurements in 19 infants (age 1 to 61 wk) undergoing elective cardiac catheterization. Twenty-seven simultaneous arterial and transcutaneous measurements revealed a good correlation between PtcO2 and PaO2 (r = .91, slope .77, intercept 3.23 torr). The mean arterial-transcutaneous PO2 difference of 10 torr (range - 15 to 35) was independent of age but was significantly correlated with skinfold thickness (r = .45, p less than .05). There was also a good correlation between StcO2 and SaO2 (r = .95, slope .65, intercept 27.8%). The mean arterial-transcutaneous oxygen saturation of 1.4% (range - 17.3 to 14) was unaffected by age or skinfold thickness. However, neither PtcO2 or StcO2 measurements were accurate in patients with severe hypoxemia; StcO2 consistently overestimated the SaO2 when the SaO2 was below 70%. Thus, in this study the discrepant PtcO2 measurements in older infants were due to increasing skinfold thickness rather than age. PtcO2 monitoring still has an important role in oxygen monitoring and together with StcO2 provides valuable information on oxygenation.

Aging↗
PubMed1986

Stimulation of parathyroid hormone secretion by EDTA infusion--a test for the differential diagnosis of hypercalcaemia.

A constant EDTA infusion of 24 mg/kg/h during 60-120 min was given to 26 patients with primary hyperparathyroidism (HPT), 8 patients with hypercalcaemia of other origin and 10 healthy control subjects. PTH and ionized calcium concentrations were measured at 5-10 min intervals. In all three groups the infusion caused a linear decrease in plasma ionized calcium. In both the HPT patients and the healthy subjects there was a prompt increase in the serum levels of parathyroid hormone (PTH) until a plateau was reached. The PTH response of the HPT patients appeared already within the hypercalcaemic range and the plateau value was attained at higher levels of PTH and ionized calcium than in the healthy subjects. The enhanced response distinguished half of the HPT patients with basal PTH values within the reference range from the healthy controls. The patients with nonhyperparathyroid hypercalcaemia displayed no increase in PTH values until the ionized calcium concentration was reduced far into or below the reference range. Thus the EDTA infusion permitted a complete differentiation between HPT and other causes of hypercalcaemia. In most cases an infusion over 30 min was sufficient for this purpose.

Adult↗
PubMed1985

Fluorometric analysis of transferable membrane pores.

When pore-forming factors insert into the hyperpolarized membranes of lipid vesicles, ion gradients are rapidly equilibrated, effecting complete depolarization. This process can be conveniently followed with a potentiometric cyanine dye. The generality of the method is demonstrated by applications to three diverse materials. The well-studied gramicidin channel is used to demonstrate that the method is sensitive down to concentrations of 10(-12)M. An extract from the shark repellent skin secretion of the Red Sea flatfish displays activity in the assay and is used to demonstrate the potential of the method to elucidate some of the characteristics of the pore, including its molecularity. That membrane-active factors can be detected and assayed in crude preparations is demonstrated with an impure extract of "amoebapore" from Entamoeba histolytica. In addition, variation of the buffer composition surrounding the vesicles can provide information about the ion selectivity of the pore under investigation.

Diffusion↗
PubMed1985

Effects of secretin on parathyroid hormone and calcium in normal subjects, patients with hyperparathyroidism and patients with gastrinoma.

In vitro studies have demonstrated that secretin can stimulate the release of parathyroid hormone (PTH), but reports concerning its effects on PTH and calcium in vivo are contradictory. To examine this question further, a bolus injection of secretin (75 IU) was given to 12 normal subjects and 10 patients with primary hyperparathyroidism (HPT). Six of the patients had multiple endocrine neoplasia and five had endocrine pancreatic tumours (EPT). Three normocalcaemic patients with EPT were also included in the study. The mean serum gastrin level rose significantly (from 19 to 40 pmol/l, p less than 0.01) within 15 min of secretin injection in the normal subjects. HPT patients without EPT had a somewhat higher mean basal level of gastrin (39 pmol/l, p less than 0.05 compared with controls), but it did not increase significantly after the secretin bolus. In six EPT patients the gastrin concentrations rose by more than 300 pmol/l. Although secretin had a biological capacity to release gastrin, it had no discernible effects on either serum PTH or serum calcium in any of the groups studied. Nor were any changes in PTH or calcium observed when secretin was given as a continuous infusion (3 IU/kg/h) over 90 min. Thus, our data do not support the concept that secretin, in vivo, is a secretagogue of PTH.

Adult↗
PubMed1985

Prealbumin in Swedish patients with senile systemic amyloidosis and familial amyloidotic polyneuropathy.

A prealbumin (PA)-like protein was demonstrated in amyloid fibrils both from a patient with senile systemic amyloidosis (SSA) and from a patient in northern Sweden with familial amyloidotic polyneuropathy (FAP). The investigated properties of this protein were similar in the two types of fibrils. The protein had molecular weight, antigenic determinants, and at least one cysteinyl residue in common with the subunit of normal PA. In contrast to normal PA, it contained disulphide-linked subunits and was to some extent bound to the fibril via the cysteinyl residues. The noncovalent forces between its subunits were weaker than in normal PA. It constituted part of the previously described AScl protein of the SSA fibrils. Proteins with lower molecular weight than the PA monomer were major proteins in both SSA and FAP fibrils. These proteins had similar properties in the two kinds of fibril and may be derived from PA. PA in serum from Swedish patients with FAP and SSA was normal with regard to the isoelectric pH of the monomers and tetramers.

Adult↗
PubMed1985

Specific food intolerance: its place as a cause of gastrointestinal symptoms.

Thirteen out of 49 patients suspected of having specific food intolerance after withdrawal and reintroduction of specific foods, were further subjected to double blind placebo controlled food challenges. Only three of these subjects were thus shown to have proven specific food intolerance. Of the remaining 10, nine were strong 'placebo reactors'. The study suggests that a small number of patients with gastrointestinal symptoms have verifiable specific food intolerance but that a greater number have symptoms attributable to psychogenic causes.

Adult↗
PubMed1985

Serum prealbumin and retinol-binding protein in the prealbumin-related senile and familial forms of systemic amyloidosis.

In a series of 13 elderly patients with proven prealbumin-related senile systemic amyloidosis (SSA), depressed serum prealbumin values (110.7 +/- 14.1 micrograms/ml) were found as compared to an age-matched control group (175.1 +/- 20.3 micrograms/ml). As expected, there was a significant correlation between serum prealbumin and serum retinol-binding proteins in both groups of patients. Patients with reactive amyloid protein AA amyloidosis had slightly depressed serum prealbumin concentrations, whereas patients with prealbumin-related familial amyloidosis of Swedish type had prealbumin values within normal limits. Since the serum levels of the acute phase reactants, haptoglobin and amyloid-related serum protein AA, were higher in the group of patients with reactive amyloidosis than in patients with SSA, the depression of the prealbumin levels in SSA is not a result of inflammation. Since SSA is known to contain prealbumin, it is possible that a disturbed prealbumin metabolism in old age results in low prealbumin serum values and deposition of amyloid.

Adult↗