Verification of the chemical composition and specifications of haemodialysis membranes by NMR and GPC-FTIR-coupled spectroscopy.

The chemical composition of a dialysis membrane is decisive towards determining its physical and biochemical properties--two fundamental determinants of the success of therapy offered to patients suffering from chronic renal failure. From the vast variety of synthetic polymers available, only a few are suitable for the manufacture of dialysis membranes that have to conform to the diverse demands of modern haemodialysis and related therapies. Recently, a membrane labelled as polyamide (Polyamide S) has caused some confusion to end-users in that the product specification for the membrane is given as 'polyarylethersulfone' or simply as Polyamide S membrane. As the chemical and physical properties of these two polymer types are distinctly different, it is unclear whether the functional characteristics of Polyamide S are to be attributed to polyamide, polyarylethersulfone, or, to both polymers. We therefore undertook investigations to ascertain the exact chemical nature of the Polyamide S membrane using a series of chemical analytical tools and an appropriate polyamide reference. The analytical techniques were conventional gel permeation chromatography (GPC), GPC-FTIR coupled spectroscopy using dimethyl acetamide and hexafluoroisopropanol as solvents and nuclear magnetic resonance spectroscopy. Glass transition temperature measurements and quantitative elemental analysis were also carried out. None of the analytical techniques used showed any traces of polyamide in Polyamide S; no aliphatic or aromatic polyamide chemical entities were detected in any of the samples tested. The Polyamide S dialysis membrane thus comprises, solely, of polyarylethersulfone, which is also known as polyethersulfone.

A collaborative end-of-life care curriculum.

Death and dying in America has received limited attention in medical education. The Southern Arizona VA Health Care System and the University of Arizona have collaborated with three nonprofit community hospice programs to develop an end-of-life care curriculum. This formal and comprehensive program is offered as a one-month elective to senior medical students, residents and fellows. The goal of the program is to improve clinical skills in caring for the dying patient and foster research in palliative and supportive care.

[The effect of di-n-octyl tin dichloride (DOTC) on immunocompetent organs and immunoreactivity of rats]. / Einfluss von Di-n-octylzinndichlorid (DOTC) auf immunkompetente Organe und Immunreaktivität von Ratten.

This article investigates the effects of di-n-octyl tin dichloride (DOTC) on some morphologic changes in spleen and thymus as well as on the immune reaction of rats. One i.v. injection of DOTC in a dose of 4 mg/kg led in female rats to an atrophy which was reversible within six weeks, and to cell depletion of the thymus. The time needed for the regeneration (the thymus indicated a dose-dependency of the action of DOTC (4-12 mg/kg) on these morphologic changes, which was established by examining immunostimulated rats. Changes in the spleen were observed only with extremely high doses of DOTC. The action of DOTC after one or repeated immunization of rats erythrocytes taken from sheep, on the daughter-cell-dependent production of antibodies was examined by means of an immuno-rosette-test and by determining the hemagglutination titre. The number of lymphocytes in the spleen which form rosettes was reduced after one intravenous administration (4 mg/kg) of DOTC 1, 2, 3, or 8 d prior to antigenic stimulation. The time needed to form rosettes was dependent on the dose. The immunoglobulin-G-immunoglobulin-M antibody titre remained unaffected if DOTC was given once by i.v. injection 7 or 8 d prior to immunostimulation, the doses ranging from 4 to 12 mg/kg. DOTC-treatment carried out twice with 4 mg/kg led to a complete suppression of the immunoglobulin-G/immunoglobulin-M antibody production against erythrocytes taken from sheep, if DOTC had been applied on eight consecutive d and on d 0 (the d of the primary immunization).(ABSTRACT TRUNCATED AT 250 WORDS)