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Biomedical subjects

B Sternberg

Publications and source records attributed to B Sternberg.

48 records · Page 3Linked to original sources
PubMedDate not supplied

Bacteriorhodopsin: the effect of bilayer thickness on 2D-array formation, and the structural re-alignment of retinal through the photocycle.

From our earlier extensive protein-lipid reconstitution studies, the conditions under which bacteriorhodopsin forms organised 2D arrays in large unilamellar vesicles have been established using freeze-fracture electron microscopy. In a background bilayer matrix of phosphatidylcholine (diC(14:0)), the protein can form arrays only when the anionic purple membrane lipid, phosphatidylglycerol phosphate (or the sulphate derivative) is present. Here we have now extended this work to investigate the effect of bilayer thickness on array formation. Phosphatidylcholines with various chain lengths (diC(12:0), diC(14:0) and diC(16:0)) and which form bilayers of well defined bilayer thickness, have been used as the matrix into which bacteriorhodopsin, together with minimal levels (c. 4-10 lipids per bacteriorhodopsin) of diphytanyl phosphatidyl-glycerol phosphate, has been reconstituted. Arrays are formed in all complexes and bhickness appears only to alter the type of array formed, either as an orthogonal or as an hexagonal array. Secondly, we have previously deduced the entire conformation of retinal within the bacteriorhodopsin binding pocket in oriented purple membrane fragments. Using solid state deuterium NMR of the specifically deutero-methylated retinal labelled at each of the methyl positions in the molecule, the C-CD(3) bond vectors of the chromophore have been resolved to +/- 2 degrees . The ring conformation is 6-S-trans, but the polyene chain is slightly curved when in the protein binding site. Here, we describe studies on the protein in both the ground state and the trapped M(412)-state of the photocycle, to show that the orientation of the central methyl group (C(19)) on the polyene chain, which is at 40 degrees +/- 1 degrees with respect to the membrane normal, only changes its orientation by approximately 4 degrees upon 13-cis-isomerization. Thus, it is the Schiff base end of the chromophore which moves upon light incidence acting as a local switch on the protein in the photocycle, whilst the ring end of the chromophore moves rather less.

Journal Article↗
PubMedDate not supplied

[Electroencephalographic problems in a department of infant resuscitation].

The authors analyse the technical problems encountered in using E.E.G. in children's reanimation. They show some examples which illustrate the importance of E.E.G. in diagnosis and therapy of such cases. Emphasis is laid upon the need for close collaboration between the EEGers and the reanimation staff.

Adolescent↗
PubMedDate not supplied

[A study of 95 families having at least two epileptic children (author's transl)].

This report concerns a study of 95 families in which at least two of the children had epilepsy (a total of 210 cases). A total of 45 p. 100 of the patients were from 60 p. 100 of the families and had an intellectual level below the average, and 32 p. 100 of them had an IQ below 70. The family history was the same whether the children were mentally deficient or not. There was no family history of mental deficiency in those families where the epileptic children had a normal IQ but there was a positive family history in 25 p. 100 of families having at least one mentally deficient and epileptic child. The persistence of seizures after 5 years of treatment is seen much more frequently in mentally deficient children than in those with normal intelligence. Finally, the position of the child within the family has no influence and epilepsy may be found in any of the children.

Epilepsies, Partial↗
PubMedDate not supplied

[Photosensitivity and colour filters (a systematic study on 1500 subjects) (author's transl)].

The reinforcing, activating, inhibiting or negative action of yellow, orange, red, green, and blue filters was studied in 1500 patients. A reinforcing action is seen much more frequently in subjects photosensitive to white light who are under twenty years old, while an inhibiting or negative action is more frequent in those over twenty. Two other factors seem to play a role in the reinforcing action of orange and red filters in subjects under twenty years old: epilepsy and cerebral immaturity. None of the non-epileptic subjects who developed a photo-convulsive response to yellow, orange, or red filters only, became epileptic during the two-year follow-up period.

Adolescent↗