Membrane dipole potentials, hydration forces, and the ordering of water at membrane surfaces.

We have compared hydration forces, electrical dipole potentials, and structural parameters of dispersions of dipalmitoylphosphatidylcholine (DPPC) and dihexadecylphosphatidylcholine (DHPC) to evaluate the influence of fatty acid carbonyl groups on phospholipid bilayers. NMR and x-ray investigations performed over a wide range of water concentrations in the samples show, that in the liquid crystalline lamellar phase, the presence of carbonyl groups is not essential for lipid structure and hydration. Within experimental error, the two lipids have identical repulsive hydration forces between their bilayers. The higher transport rate of the negatively charged tetraphenylboron over the positively charged tetraphenylarsonium indicates that the dipole potential is positive inside the membranes of both lipids. However, the lack of fatty acid carbonyl groups in the ether lipid DHPC decreased the potential by (118 +/- 15) mV. By considering the sign of the potential and the orientation of carbonyl groups and headgroups, we conclude that the first layer of water molecules at the lipid water interface makes a major contribution to the dipole potential.     

Analytical model of corneal surgery

We present a model of the human cornea in order to study the changes in its shape resulting from surgical operations (e.g., radial keratotomy). A simple closed-form solution is given for a thin linearly elastic spherical shell model of the cornea. We assume axisymmetry and isotropy in the shell surface. The surgery is modeled by permitting Young's modulus and shell thickness to depend on position. The analytical nature of the solution permits principal shell curvatures to be explicitly calculated. The model is used to investigate the effect of surgery on corneal flattening and the associated sensitivity to intraocular pressure changes.     

Lipogenesis from ketone bodies in the perfused rat liver: effects of acetate and ethanol

The interactions between acetate or ethanol metabolism, lipogenesis, and ketone body utilization have been studied in isolated livers from fed rats perfused with 15 mM glucose and 10 mM acetate or ethanol. The contribution of acetate to ketogenesis is constant; on the other hand, the contribution of ethanol to ketogenesis increases with time, presumably because of the accumulation of acetate in the perfusate. Ketogenesis is decreased in the presence of ethanol (but not acetate), while ketone body utilization is not affected by ethanol or acetate. Acetate contributes one third and ethanol contributes one half of the carbon incorporated into fatty acids and 3-beta-hydroxysterols. Only a small fraction (less than 5%) of the incorporation of acetate or ethanol into fatty acids and sterols occurs via transient incorporation into ketone bodies.     

Social perceptions of the effects of Down syndrome facial surgery: a school-based study of ratings by normal adolescents

This study examines how 277 normal adolescents from five Israeli schools perceive the Down syndrome face before and after plastic surgery. A seven-point Likert scale was used to rate slides of normal and Down syndrome faces on four dimensions. Down syndrome patients were seen as less attractive, intelligent, good-hearted, and socially appealing than normal individuals. The slides were in nonapparent order and contained preoperative and 1-year postoperative views of eight plastic surgical patients. Paired t tests were used to examine operative changes, and all four dimensions showed overall postoperative improvement (p less than 0.001), but case-to-case variation was considerable. A linear relationship was found between change in appearance ratings and change in intelligence ratings. Findings suggest that when improvements in facial appearance are realized, peer normal social perceptions of the Down syndrome child may be enhanced. The relationship between school placement, intellectual level, and surgical decision making is discussed.     

Isolation and partial characterization of plasma membrane fatty acid binding proteins from myocardium and adipose tissue and their relationship to analogous proteins in liver and gut

We describe a general method for isolating a class of 40 kDa plasma membrane fatty acid binding proteins which have been identified previously only in rat liver and jejunum. Proteins extracted with 2 M salt from rat adipocyte and cardiac myocyte plasma membranes were subjected to preparative isoelectric focusing. Fractions with pI's greater than or equal to 9.0 were further purified by oleate-agarose affinity chromatography and HPLC. Each tissue yielded a single 40 kDa protein which co-chromatographed with [3H]-oleate on gel permeation HPLC, and reacted on Western blots with an antibody to the corresponding hepatic membrane protein. Related plasma membrane fatty acid binding proteins have now been isolated from each of the major sites of fatty acid transport.     

General practitioner obstetrics in Bradford.

The standard of obstetrics care by general practitioners in Bradford was assessed by reviewing the case records of all women who in 1988 were booked for delivery under their general practitioner but subsequently required transfer to consultant care. A total of 5885 women were delivered in Bradford during 1988. Of 1289 booked under their general practitioner, 637 required transfer to consultant care. In 259 cases transfer occurred during labour; only 37 of these women were visited by their general practitioner. Many of the problems that precipitated transfer were predictable and some were considered preventable: 263 of the women transferred were considered unsuitable for booking by general practitioners. The perinatal mortality among women booked under their general practitioner was 10.1/1000 and the stillbirth rate 7.8/1000. These figures are high and suggest a need for tighter controls over the qualifications and experience of doctors participating in a fully integrated system of obstetric care.     

Nitrosamine carcinogenicity: a quantitative Hansch-Taft structure-activity relationship

Statistically significant correlations have been demonstrated between carcinogenic activity, water-hexane partition coefficients and electronic factors for an extensive series of N-nitroso compounds. Electronic factors were expressed by the Taft sigma* values of substituents on the carbon atoms alpha to the N-nitroso group. Such correlations indicate that transport of the carcinogen to its active site has an important effect on its potency. The correlations also implicate reactivity at the alpha-carbon in the determination of carcinogenic activity and point out various structural types which do not follow the general rule.