Adhesion of platelets to human artery subendothelium: effect of factor VIII-von Willebrand factor of various multimeric composition

The relationship between the multimeric size of factor VIII-von Willebrand factor (FVIII-vWF) and the support of platelet adhesion to subendothelium was studied in an annular perfusion chamber, employing human renal and umbilical arteries. Commercial factor VIII concentrates containing multimers of low molecular weight that had been shown not to correct the bleeding time upon infusion into patients with von Willebrand's disease did not support platelet adhesion in the perfusion chamber. Cryoprecipitate and two experimental FVIII-vWF concentrates containing multimers of high molecular weight supported platelet adhesion. Factor VIII-vWF purified from cryoprecipitate was subdivided into three fractions of different molecular weights (6.0-14.0, 4.0-9.0, and 3.0-7.5 X 10(6) dalton). These fractions appeared to bind equally well and to be equally effective in supporting platelet adhesion. Factor VIII-vWF with multimers of low molecular weight (0.5-1.5 X 10(6) dalton) were prepared by partial reduction. Binding of FVIII-vWF to subendothelium was not impaired, and the support of platelet adhesion appeared to be more resistant to the effect of reduction than the ristocetin cofactor activity. At high shear rate (2,500 sec-1), increased platelet adhesion was observed with partially reduced FVIII- vWF. These data indicate that the ability of FVIII-vWF preparations to correct the bleeding time is reflected in enhanced platelet adhesion to subendothelium in a perfusion chamber. These data also emphasize that multimeric size is not the only factor determining whether FVIII-vWF will support platelet adhesion.     

A Novel Neutrotrophic Property Of Glucagon-Like Peptide 1: A Promoter Of Nerve Growth Factor-Mediated Differentiation In PC12 Cells

The insulinotropic hormone glucagon-like peptide-1 (7-36)-amide (GLP-1) has potent effects on glucose-dependent insulin secretion, insulin gene expression, and pancreatic islet cell formation and is presently in clinical trials as a therapy for type 2 diabetes mellitus. We report on the effects of GLP-1 and two of its long-acting analogs, exendin-4 and exendin-4 WOT, on neuronal proliferation and differentiation, and on the metabolism of two neuronal proteins in the rat pheochromocytoma (PC12) cell line, which has been shown to express the GLP-1 receptor. We observed that GLP-1 and exendin-4 induced neurite outgrowth in a manner similar to nerve growth factor (NGF), which was reversed by coincubation with the selective GLP-1 receptor antagonist exendin (9-39). Furthermore, exendin-4 could promote NGF-initiated differentiation and may rescue degenerating cells after NGF-mediated withdrawal. These effects were induced in the absence of cellular dysfunction and toxicity as quantitatively measured by 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and lactate dehydrogenase assays, respectively. Our findings suggest that such peptides may be used in reversing or halting the neurodegenerative process observed in neurodegenerative diseases, such as the peripheral neuropathy associated with type 2 diabetes mellitus and Alzheimer's and Parkinson's diseases. Due to its novel twin action, GLP-1 and exendin-4 have therapeutic potential for the treatment of diabetic peripheral neuropathy and these central nervous system disorders.     

Congenital cardiac anomalies with vein of Galen malformations in infants

Published reports and personal experience are reviewed relating to patients under 1 year of age diagnosed with a vein of Galen malformation and congenital heart disease. Including five patients from this institution, a total of 23 patients (12 neonates) with congenital heart disease and a vein of Galen malformation have been reported. Six of these had sinus venosus atrial septal defect and nine had aortic coarctation.     

Endothelin and neutral endopeptidase in the endometrium of women with menorrhagia

The mechanisms underlying excessive menstrual bleeding or menorrhagia are not understood. In view of its potent vasoconstrictor and growth factor properties, endothelin has been proposed to have a potential paracrine role in the regulation of uterine blood flow and therefore could be a factor in menorrhagia. We compared the cellular localization of endothelin and its metabolizing enzyme, neutral endopeptidase, in endometrial biopsies from women with documented menorrhagia and in those with a normal menstrual cycle. Menorrhagia was documented by measurement of menstrual blood loss, 146 +/- 141 ml (median +/- SD). Endothelin and neutral endopeptidase were localized by immunohistochemistry, and the staining intensity was graded. Their immunostaining patterns were found to differ in menorrhagia compared to the normal menstrual cycle. Endothelin was reduced in glandular epithelium in menorrhagia and did not vary cyclically, while neutral endopeptidase was increased in the glandular epithelium. In menorrhagia, stromal endothelin immunoreactivity was not different from the normal cycle and although neutral endopeptidase immunostaining in stroma was similar to the secretory phase of normal endometrium, cyclical variation was absent. The potential for increased metabolism of endothelin could be an explanation for the decreased endothelin immunostaining in the glandular epithelium.