Inheritance pattern of platelet membrane fluidity in Alzheimer disease.

The fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene in labeled platelet membranes, an index of membrane fluidity, is a stable, familial trait that is associated with a clinically distinct subtype of Alzheimer disease. Complex segregation analysis of this continuous variable was performed on 95 members of 14 pedigrees identified through probands who had autopsy-confirmed or clinically diagnosed Alzheimer disease. The results suggest that platelet membrane fluidity is controlled by a single genetic locus, PMF, with two alleles that have additive effects. The PMF locus appears to explain approximately 80% of the total variation in platelet membrane fluidity within the families of patients with Alzheimer disease.     

Meeting report: membrane proteins in health and disease.

This article summarizes the scientific presentations made at a Canadian Society of Biochemistry and Molecular & Cellular Biology Symposium on "Membrane Proteins in Health and Diseases" and two satellite meetings on "Bicarbonate Transporters" and "Nucleoside Transporters" held in Banff, Alberta, 20-24 March 2002. Membrane proteins are encoded by about 1/3 of genes and are involved in a wide range of essential functions, including the transport of nutrients, ions, and waste products across biological membranes. Mutations or changes in the expression of these genes cause an equally wide range of diseases. Membrane proteins are also common drug targets or provide drug entry mechanisms. The importance of membrane proteins in biology and medicine was highlighted by the presentations made at this exciting meeting by an international group of experts.     

Effect of positive-pressure breathing on aADN2 in hyaline membrane disease.

In seven subjects with hyaline membrane disease and breathing 40-70% oxygen in nitrogen, the effect of continuous positive-pressure breathing (CPPB) was examined by application of a continuous negative pressure (10 cm water) about the thorax and assessment of the alveolar-arterial tension differences for nitrogen (aADn2) and oxygen (AaDo2). On CPPB, there was a decrease in the aADn2 by a mean 9 mmHg and a decrease in the AaDo2 by a mean 44 mmHg. This corresponded to a decrease in the total venous admixture (Qva/Qt) of 0.20 and to a decrease in the venous admixture due to a true right-to-left shunt (Qs/Qt) of 0.19. These data were interpreted to mean a significant improvement in Va/Qc imbalance within open ventilated parts of the lung, which could be responsible, particularly by relief of local alveolar hypoxia, for reduction of the pulmonary vascular resistance and the true right-to-left shunt.