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Biomedical subjects

P Amendt

Publications and source records attributed to P Amendt.

At least 37 records · Page 2Linked to original sources
PubMed1988

The hyperinsulinaemic hypoglycaemias in infancy: a study of six cases.

The aim of the present study was to evaluate various functional tests for the differentiation of hyperinsulinaemic hypoglycaemia. The pathophysiological and histological findings in six infants, aged 2-7 months, with persistent hyperinsulinaemic hypoglycaemia are described. Islet cell adenoma was found in four infants and pancreatic nesidioblastosis in two others. Circulating levels of blood glucose (BG), immunoreactive insulin and C-peptide immunoreactivity were measured under basal conditions and during both stimulation and suppression. The diagnosis of hyperinsulinaemia was made by estimation of the BG/serum insulin ratio, which was the most important diagnostic criterion of hyperinsulinism. Control subjects of comparable age showed a ratio of 8.3 +/- 4.4 (range 4.1-13.3), whereas the six patients had values between 0.3 and 5.1. At least four determinations with ratios lower than 2.6 were necessary for confirming the diagnosis. Preoperatively we performed oral glucose tolerance, diazoxide infusion, somatostatin infusion and C-peptide suppression tests. It is suggested that the various function tests, especially the suppression tests, do not differentiate hyperinsulinism caused by an adenoma from that caused by diffuse pancreatic nesidioblastosis.

Biopsy↗
PubMed1987

Measurement of insulin in human sera using a new RIA kit. 1. Insulin determination in the absence of insulin antibodies--conventional assay and micro modification.

A sensitive and versatile radioimmunoassay (RIA) for insulin was established using human insulin standard, a specific guinea pig anti-insulin antiserum and rabbit anti-guinea pig serum. Radioiodination was performed according to a modified chloramine T method. Tracer preparations were used for as long as 6 weeks after iodination. The standard curve ranges from 0.044 to 1.2 nmol/l. The intra-assay coefficient of variation (CV) was 3-5% and the inter-assay CV was 6-9% in the optimal range between 0.4 and 0.9 nmol/l. The average recovery of human insulin added to plasma or serum samples was 100.2 +/- 2.0% (n = 38) and 100.1 +/- 1.9% (n = 42), respectively. In addition to human insulin, porcine, canine, rabbit and bovine insulin can also be determined but not rat or mouse insulin. The cross-reactivity of the antiserum with porcine proinsulin was found to be 40% on the molar basis. The range of mean fasting plasma insulin concentrations in healthy subjects and under various pathological conditions were estimated.

Humans↗
PubMed1986

Pancreatic endocrine tumours: histological, immuncytochemical and electronmicroscopical investigations.

Fifteen endocrine pancreatic tumours (8 insulinomas, 3 gastrinomas, 1 vipoma, 3 tumours without hormonal activity) and two cases with dysplasia of the endocrine pancreas are reported. Immunohistochemical and electronmicroscopical investigations produced evidence of multihormonality in adenomas that clinically appeared to be monohormonal. The S-phase fraction of such tumours is below 1% which indicates their low proliferative potential. The malignancy of endocrine pancreatic tumours cannot be seen from cytochemical or histological symptoms; it can be established with certainty only from the presence of metastases. Multiple endocrine adenomas should suggest the possibility of hereditary endocrine polyadenomatosis. Hyperplasia and distribution disorder of the endocrine tissue as well as pathologically increased nesidioblastic activity represent the morphologic substrate of dysplasia of the endocrine pancreas as a potential cause of hyperinsulinaemic hypoglycaemia in infancy.

Adenoma, Islet Cell↗
PubMed1983

[The endocrine pancreas in pluriglandular neoplasia type I. A report of two cases and review of the literature].

The changes of the endocrine pancreas in two cases of pluriglandular neoplasia type I were studied. A 15 year-old girl showed an amyloid containing ductuloinsular B cell adenoma, microadenomas and nesidioblastic processes. The simultaneous presence of hyperprolactinemia and nephrolithiasis indicates the existence of the endocrine polyadenomatosis. A 33 year-old woman had four amyloid containing B cell adenomas with ductular proliferation, a main cell adenoma of the parathyroid and a prolactinoma of the adenohypophysis. Solitary or multiple ductuloinsular adenomas, amyloid of the endocrine type and nesidioblastic activity are not specific features of the endocrine pancreas in pluriglandular adenomatosis. Similar structures can be found in isolated islet cell tumors or in nesidioblastosis. Ductuloinsular proliferations can also be observed in chronic pancreatitis.

Adolescent↗