Effects of pure oxygen atmosphere in vivo on plasma lecithin-cholesterol acyltransferase reaction

Exposure to pure oxygen atmospheres for more than three days resulted in loss of red blood cell mass in astronauts in some flights. Oxidation of lipid or protein membrane components may account for this phenomenon, since tocopherol deficient red blood cells have been shown to hemolyze on exposure to elevated oxygen pressures in vitro and in vivo. An additional contributing cause to the induced red cell loss may be the inhibition of the plasma lecithin-cholesterol acyltransferase reaction by oxygen, since congenital absence of the enzyme is associated with anemia. This possibility was explored in eight human subjects who lived in a sealed environmental chamber and breathed 100% oxygen at 258 mm Hg pressure for 30 days. In their plasma a 40% decrease in the conversion of free cholesterol to ester was demonstrated in vitro after four weeks’ exposure to 100% oxygen. Plasma cholesteryl ester concentration was also decreased. Red blood cell mass was reduced and erythropoiesis was depressed. These findings support the hypothesis that the anemia induced by exposure to 100% oxygen was caused in part by decreased synthesis of cholesteryl esters secondary to an inhibition of the plasma lecithin-cholesterol acyltransferase reaction.     

Robust inference of baseline optical properties of the human head with three-dimensional segmentation from magnetic resonance imaging

We model the capability of a small (6-optode) time-resolved diffuse optical tomography (DOT) system to infer baseline absorption and reduced scattering coefficients of the tissues of the human head (scalp, skull, and brain). Our heterogeneous three-dimensional diffusion forward model uses tissue geometry from segmented magnetic resonance (MR) data. Handling the inverse problem by use of Bayesian inference and introducing a realistic noise model, we predict coefficient error bars in terms of detected photon number and assumed model error. We demonstrate the large improvement that a MR-segmented model can provide: 2-10% error in brain coefficients (for 2 x 10(6) photons, 5% model error). We sample from the exact posterior and show robustness to numerical model error. This opens up the possibility of simultaneous DOT and MR for quantitative cortically constrained functional neuroimaging.     

Film coated pellets containing verapamil hydrochloride: enhanced dissolution into neutral medium

Weakly basic drugs, such as verapamil hydrochloride, that are poorly soluble in neutral/alkaline medium may have poor oral bioavailability due to reduced solubility in the small intestine and colon. Film coated pellets were prepared using two strategies to enhance drug release at high pH values. Firstly, pellets were coated with Eudragit RS/hydroxypropyl methylcellulose acetate succinate (HMAS) mixtures in proportions of 10:1 and 10:3, respectively. The enteric polymer, HMAS, would dissolve in medium at pH > 6 creating pores through the insoluble Eudragit RS membrane to increase drug release. Secondly, an acidic environment was created within the core by the inclusion of fumaric acid at concentrations of 5 and 10% in order to increase drug solubility. Both strategies enhanced drug release into neutral medium in dissolution studies using the pH change method to simulate GIT transit. Dissolution profiles of samples tested in pH 1.2 for 12 hr were compared with those using the pH change method (pH 1.2 for first 1.5 hr, pH raised to 6.8 for remaining 10.5 hr) using the area under the dissolution curve (AUC), the dissolution half-life (t50%), and the amount of drug released in 3 hr (A3hr) values. Both strategies enhanced drug release into neutral medium although the strategy using HMAS in the film was more effective. The formulation least affected by pH change was a combination of the two strategies, i.e., pellets containing 5% fumaric acid coated with Eudragit RS 12% w/w and HMAS 1.2% w/w.     

Further systematic research with biorhythms.

Results from 5 studies (e.g., determining whether 32 US presidents died on critical days) show that biorhythm status did not appear to be useful for predicting behavior. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pluralistic ignorance: When similarity is interpreted as dissimilarity.

Pluralistic ignorance occurs when individuals infer that the identical actions of the self and others reflect different internal states. We propose that pluralistic ignorance arises most commonly in contexts where individuals believe that fear of embarrassment is a sufficient cause for their own behavior but not for the behavior of others. Three predictions derived from the proposed analysis were tested. In Experiment I, we examined the hypothesis that people believe that they possess more of those traits that lead to social inhibition than do others. Ratings of the self and the average other on a series of trait dimensions supported this hypothesis. In Experiment 2, we pursued the hypothesis that people believe that fear of embarrassment is a more potent determinant of their own behavior than of the behavior of others. Subjects first were given an opportunity to engage in or refrain from engaging in an action that potentially had both beneficial and embarrassing consequences. They then were asked to estimate the percentage of other subjects whom they believed would act similarly. Consistent with the predictions, subjects both avoided the embarrassing course of action and overestimated the percentage of others who took it. In Experiment 3, groups of subjects were placed in the same context that confronted the individual subjects in Experiment 2. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Accessible designs in Solvay cluster synthesis

Solvay clusters are sets of intermediate chemical reactions that execute a desired net reaction. We show that May-Rudd polygons give access to all Solvay clusters that involve two and three intermediate reactions regardless of the number of chemical species involved, and to all clusters that involve fewer than nine chemical species regardless of the number of chemical reactions. More elaborate Solvay clusters are accessible providing they exhibit a planar topological structure.     

Emetic and electric shock alcohol aversion therapy: Six- and twelve-month follow-up.

Reports follow-up data for 20 male alcoholics who received either a multifaceted inpatient alcoholism treatment program alone (controls) or emetic or shock aversion therapy in addition to that program. Results indicate that emetic treatment exerted a modest beneficial effect at the 6-mo mark, but control and emetic Ss did not differ at the 12-mo mark. Both emetic and control Ss compiled more days of abstinence than shock Ss at both follow-up intervals. Analysis of the relationship between inpatient measures of the strength of alcohol aversions and posttreatment drinking revealed an inverse relationship between heart rate response to alcohol and number of days of drinking. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential utilization of syntactic and semantic information by skilled and less skilled readers in the intermediate grades.

Administered to 270 4th–6th graders the Culture Fair Intelligence Test and the Comprehension subtest of the Gates-MacGinitie Reading Tests. Matched pairs of skilled and less skilled readers then read aloud a variety of material in cloze procedure format and printed in geometric transformations. The extent to which the syntactic and semantic constraints of the text guided their performance was assessed. Both on the cloze procedure and the transformed texts, skilled readers made greater use of grammatical and contextual information. Furthermore, there was no significant improvement across grade levels in the proportions of syntactically and semantically appropriate responses. The stability of differences between skilled and less skilled readers suggests the possibility that differential utilization of syntactic and semantic cues by beginning readers might contribute to differences among them in the development of reading skill. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

What constitutes a self-serving attributional bias? A reply to Bradley.

In a response to G. W. Bradley's (see record 1979-26025-001) article, the value of his "broadened self-serving bias formulation" is examined, and a case is made for clearly delineating different types of self-serving attributions. It is contended that there is still little support for the hypothesis that individuals alter their perception of causality so as to protect or enhance their self-esteem. (2 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)