Twenty-four-hour serum growth hormone, insulin, C-peptide and blood glucose profiles and serum insulin-like growth factor-I concentrations in women with polycystic ovaries.

Raised insulin levels are now recognized as a characteristic feature of women with polycystic ovaries (PCO), and hyperinsulinism has been shown to stimulate androgen production in such women. We have, however, recently shown that hyperinsulinaemia is present only in the obese subjects with PCO in whom insulin concentrations correlate with those of luteinizing hormone. We therefore studied 24-hour blood profiles of growth hormone (GH) and insulin-like growth factor-I (IGF-I) in obese and non-obese women with PCO, for comparison with their levels of insulin, C-peptide and other hormones, such as androgens which are known to be disturbed in PCO. Mean 24-hour GH levels were higher overall in PCO than in control subjects, although the difference was not significant. When, however, a separate analysis was made in obese as compared with non-obese PCO patients, GH concentrations were significantly higher in the non-obese group than in the obese (p = 0.0005). There was a significant negative correlation between body mass index and mean 24-hour GH concentrations (r = -0.641; p = 0.0006). IGF-I concentrations were however similar in the PCO group overall and in controls, as well as in the obese and non-obese PCO patients. The 24-hour blood glucose profile pattern was significantly different in PCO women from controls (p = 0.009), with absence of post-prandial peaks in blood glucose concentrations. These changes were most marked in the non-obese PCO group, who also had significantly lower blood glucose levels than either controls or obese PCO subjects.(ABSTRACT TRUNCATED AT 250 WORDS)     

The modulatory effect of membrane viscosity on structural and functional properties of the anion exchange protein of human erythrocytes

The sterol content of human erythrocyte membranes was modified by polyvinylpyrrolidone (PVP)-mediated enrichment or depletion of cholesterol (CHL) or incorporation of cholesteryl hemisuccinate (CHS). The effects of these modifications on osmotic fragility and anion exchange protein (AEP) disposition and function were evaluated. CHS enrichment was fast (1 hr, 37 degrees C) and led to a concentration-dependent crenation as well as a decrease in osmotic cell fragility, in parallel with increased membrane microviscosity. CHL caused similar but considerably less marked effects due to slower incorporation rates into membranes. CHS enrichment of cells induced susceptibility of AEP to trypsin, a protease which otherwise does not affect AEP in intact cells. Although transport rates of monosaccharides, nucleosides, and anions were markedly slowed down by CHS enrichment of cells in parallel with increased membrane viscosity, anion transport was the most affected. The temperature profile of anion transport in CHS-enriched cells revealed a 10-kcal/mol increase in the enthalpy of activation relative to normal cells. Anion transport measured in heteroexchange conditions (Cl in--pyruvate out) and (Cl in-sulfate out) was relatively more susceptible to CHS modification than when it was measured in homoexchange conditions (Cl in-Cl out). The results of these measurements indicate that CHS-mediated increase in membrane viscosity affects AEP translocation capacity and transmembrane disposition via changes in lipid compressibility. Specific effects of CHS on AEP function, however, could not be ruled out.     

Diffusion within egg lecithin bilayers resembles that within soft polymers

An analysis is presented of how the permeability coefficient/octanol:water partition coefficient ratio for 33 different chemical substances crossing egg lecithin bilayers depends on the molecular volume of the substances. From this analysis we conclude that bilayers made from egg lecithin behave as soft polymers in their discrimination between permeants of different sizes and shapes.     

Distribution of coelobites (cavity-dwellers) in coral rubble across the Florida Reef Tract

The interstices of coral rubble, the most common deposits of many reefs, provide extensive surfaces for a variety of sessile and vagile coelobites (cavity-dwellers). In the northern Florida Reef Tract there are at least 80 different sessile coelobites in coral rubble collected from 21 stations from in-shore lagoon to fore-reef, depth 40 meters. Three microzones of coelobites on the undersides of rubble were distinguished on the bases of their dominant community assemblages; algal microzone in the peripheral area, sponge-bryozoan microzone in the transitional area, and foraminiferal microzone in the central area. In the transect that extends some 6–7 km across the reef tract, the biomass is largest in the rubble of the shallow (1–3 m) shelf margin and it decreases shoreward and in deeper water; however, the maximum variety of species comes in the fore-reef at depths of about 20–30 m. Four coelobite zones are recognized in the reef transect based on distribution pattern and relative abundance of diagnostic species; 1) in-shore lagoon zone, 2) lagoon-reef zone, 3) marginal reef zone, and 4) fore-reef zone. Although this paper does not propose a comprehensive explanation for the distribution of coelobites, it does emphasize the importance of two factors that affect coelobite development and distribution: interstitial sediment as a negative (limiting) factor and flushing as a positive factor.