Tactile discrimination of direction of lines in relation to hemispheric specialization

The role of the right hemisphere in a task of haptic discrimination of line orientation was studied in 16 children aged 7.6 and 16 adults aged 25 yr. The exploratory movements were limited to hand and wrist, since it has been shown that distal movements are mediated by the contralateral hemisphere. A comparison of the performance of the two hands shows a clear superiority of the left hand and inferred right hemisphere in both children and adults. An special emphasis in the discussion is given to the role of the experimental procedure in enhancing the effect of the hemispheric functional asymmetries.

[Molecular organization of erythrocyte membranes in Duchenne muscular dystrophy]

Lipid-soluble spin labels were used to study lipid protein interactions in erythrocyte membranes obtained from patients with Duchenne muscular dystrophy. The temperature dependence of order parameter (Sn) and correlation time (tau c) have demonstrated alterations in the surface and in the hydrophobic core of membrane; the differences might be correlated with a depletion of extrinsic protein and of intramembrane particles. Our studies suggest a great abnormality of membrane molecular organization in Duchenne muscular dystrophy.

[Study of lipid-protein interactions in mitochondrial membranes using the intrinsic fluorescence of tryptophan]

The environment of membrane-bound proteins has been investigated by measuring the fluorescence of intrinsic tryptophans in intact bovine heart mitochondria, in lipid-depleted mitochondria, and in reconstituted mitochondria. Lipid depletion induces a strong decrease of fluorescence intensity, probably as the result of extraction of peripheral proteins by the solvents used. Comparison of lipid-depleted and lipid-reconstituted mitochondria shows a higher fluorescence in the lipid-depleted membranes; in an Arrhenius plot the fluorescence intensity shows two breaks in the lipid-depleted membranes, but no break in the reconstituted ones. Butanol has little effect on fluorescence intensity of intact mitochondria. The results are compatible with a constant lipid environment of integral proteins which is not modified by either temperature or organic solvents.

Insulin receptors on monocytes and erythrocytes from obese patients

Insulin receptors were studied in monocytes and erythrocytes [red blood cells (RBC)] isolated from 15 normal and 15 nondiabetic obese outpatients on an unrestricted diet. Insulin binding on both monocytes (P < 0.001) and RBC (P < 0.01) was higher in normal than in obese subjects due to different receptor concentrations. In some obese patients, binding to monocytes was decreased, while binding to RBC was normal. These data demonstrate that obese out-patients on an unrestricted diet have a reduced number of insulin receptors. It is suggested that interpretation of insulin binding based upon RBC should be used with caution, since a discrepancy exists in some subjects in the results obtained with these cells and monocytes.