Dynamic changes of serum gamma-glutamyl transferase in chronic alcoholism.

Elevated serum gamma-glutamyl transferase (GGT) levels were found in 29% of 155 chronic alcoholics undergoing detoxification treatment. Alkaline phosphatase (AP) was increased in 16%, alanine aminotransferase--SGPT (ALT) in 12% of the patients, while 23% had elevations of either AP or ALT or both. Of the foregoing parameters, GGT was the best single indicator of liver involvement. In course of the follow-ups GGT/ALT correlation improved, but GGT/AP correlation deteriorated. In 9 patients, abstinence during follow-up was associated with progressive decrease in previously elevated serum GGT. Because of its unique sensitivity, GGT may be useful as a screening and/or monitoring aid in alcoholism.     

Coupled Diffusion of Peripherally Bound Peptides along the Outer and Inner Membrane Leaflets

Transmembrane signaling implies that peripheral protein binding to one leaflet be detected by the opposite leaflet. Therefore, protein recruitment into preexisting cholesterol and sphingolipid rich platforms may be required. However, no clear molecular picture has evolved about how these rafts in both leaflets are connected. By using planar lipid bilayers, we show that the peripheral binding of a charged molecule (poly-lysine, PLL) is detected at the other side of the bilayer without involvement of raft lipids. The diffusion coefficient, D_P, of PLL differed by a factor of √2 when PLL absorbed to one or to both leaflets of planar membranes. Fluorescence correlation spectroscopy showed that the changes of the lipid diffusion coefficient, D_M, were even more pronounced. Although D_M remained larger than D_P on PLL binding to the first membrane leaflet, D_M dropped to D_P on PLL binding to both leaflets, which indicated that the lipids sandwiched between two PLL molecules had formed a nanodomain. Due to its small area of ∼20 nm² membrane electrostriction or leaflet interaction at bilayer midplane can only make a small contribution to interleaflet coupling. The tendency of the system to maximize the area where the membrane is free to undulate seems to be more important. As a spot with increased bending stiffness, the PLL bound patch in one leaflet attracts a stiffening additive on the other leaflet. That is to say, instead of suppressing undulations in two spots, two opposing PLL molecules migrate along a membrane at matching positions and suppress these undulations in a single spot. The gain in undulation energy is larger than the energy required for the alignment of two small PLL domains in opposite leafs and their coordinated diffusion. We propose that this type of mechanical interaction between two membrane separated ligands generally contributes to transmembrane signaling.     

Port Health Control

Almost 950,000 of the 21 million passengers passing through London (Heathrow) Airport in 1973 were seen by the health control unit, which is run by the London Borough of Hillingdon. The unit provides 24-hour medical cover and its responsibilities include x-ray examination for tuberculosis and screening passengers from smallpox-infected areas. It is suggested that, in view of changing epidemiological patterns throughout the world, there is a need to modify existing procedures rather than to abandon them. The development of a follow-up system for tracing passengers at risk and improvements in presenting information about health risks to intending travellers are advocated. While such proposals might be opposed, they could be practicable.     

Dexamethasone causes translocation of glucose transporters from the plasma membrane to an intracellular site in human fibroblasts

To investigate the mechanism by which glucocorticoids inhibit glucose transport in peripheral tissues, we have used a monoclonal antibody directed against the human glucose transporter to measure the relative amounts of glucose transporter polypeptide in various cell fractions of human foreskin fibroblasts after treatment with and without dexamethasone. In cells treated for 4 h with 100 nM dexamethasone, a decrease of 48% in glucose transport was accompanied by a decrease of 40% in the amount of glucose transporter polypeptide in a plasma membrane fraction enriched 10-fold in 5'-nucleotidase activity and a 78% increase in the amount of transporter polypeptide in a fraction of putative intracellular membranes, designated P2. There was no significant change in the amount of transporter polypeptide in whole cell lysates. Insulin (200 nM) stimulated glucose transport in basal fibroblasts by only 9%. However, addition of insulin for 30 min to cells that had been treated for 4 h with dexamethasone completely reversed the dexamethasone-induced decrease in glucose transport and also reversed the dexamethasone-induced changes in glucose transporter polypeptide content of the plasma membrane and P2 fractions. From these observations we conclude that dexamethasone decreases glucose transport by causing translocation of glucose transporters from the plasma membrane to an internal location and that insulin reverses the dexamethasone effect by reversing the translocation.     

Leaf hydrocarbons of Phacelia species (hydrophyllaceae)

Whole leaf hydrocarbons of six species of Phacelia were investigated for their variability among natural Californian populations, and for adaptive     

Contrasting roles for c-Myc and L-Myc in the regulation of cellular growth and differentiation in vivo.

Although myc family genes are differentially expressed during development, their expression frequently overlaps, suggesting that they may serve both distinct and common biological functions. In addition, alterations in their expression occur at major developmental transitions in many cell lineages. For example, during mouse lens maturation, the growth arrest and differentiation of epithelial cells into lens fiber cells is associated with a decrease in L- and c-myc expression and a reciprocal rise in N-myc levels. To determine whether the down-regulation of L- and c-myc are required for mitotic arrest and/or completion of differentiation and whether these genes have distinct or similar activities in the same cell type, we have studied the consequences of forced L- and c-myc expression in the lens fiber cell compartment using the alpha A-crystallin promoter in transgenic mice (alpha A/L-myc and alpha A/c-myc mice). With respect to morphological and molecular differentiation, alpha A/L-myc lenses were characterized by a severely disorganized lens fiber cell compartment and a significant decrease in the expression of a late-stage differentiation marker (MIP26); in contrast, differentiation appeared to be unaffected in alpha A/c-myc mice. Furthermore, an analysis of proliferation indicated that while alpha A/L-myc fiber cells withdrew properly from the cell cycle, inappropriate cell cycle progression occurred in the lens fiber cell compartment of alpha A/c-myc mice. These observations indicate that continued late-stage expression of L-myc affected differentiation processes directly, rather than indirectly through deregulated growth control, whereas constitutive c-myc expression inhibited proliferative arrest, but did not appear to disturb differentiation. As a direct corollary, our data indicate that L-Myc and c-Myc are involved in distinct physiological processes in the same cell type.