The effect of a loud buzzer upon the acquisition and extinction of a simple avoidance response in rats.

Bishop's U., Lennoxville, Quebec, Canada (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Difference Fourier analysis of "surface features" of bacteriorhodopsin using glucose-embedded and frozen-hydrated purple membrane

A difference Fourier map of the projected structure of bacteriorhodopsin has been synthesized from electron diffraction amplitudes collected from membranes prepared in the glucose-embedded state and the frozen-hydrated state. Phases of a recently published data set for glucose-embedded specimens were used for the difference Fourier map. Moderate resolution (9 A) and high resolution (4.25 A) maps both indicate that glucose is exchangeable for water in the region of the map corresponding to the lipid regions. We interpret this as indicating that there is a small surface depression in this region of the structure. The depth of this feature is estimated to be 1/6 the thickness of the protein region in the membrane. The data obtained in this study rules out the existence of an aqueous transmembrane channel, the dimensions of which are large enough to allow free exchange of glucose for water. Several new features are also observed in the protein region of the membrane. These features are probably due to segments of the polypeptide at the aqueous interface that are well ordered in frozen-hydrated specimens but not in glucose-embedded specimens. Candidate structures for the origin of these features are extensions of the helices, or linker regions connecting the helices.     

The role of Ga2O3 in the preparation of Y2O3:Eu3+ phosphor from the oxides

It has been observed that Ga₂O₃ enhances the cathodeluminescence and the 2537 Å-excited photoluminescence, and also causes whitening of the body colour of Y₂O₃:Eu²⁺ prepared from the oxides. In both types of luminescence, these effects are apparently due to the Ga₂O₃ behaving as a mineraliser, i.e. a diffusion enhancer. In the case of photoluminescence, additional brightness enhancement resulting from incorporation of Ga₂O₃ is due to a type of sensitisation to the exciting wavelength.     

Diverse clinical compounds alter the quaternary structure and inhibit the activity of an essential enzyme

An in vitro evaluation of the Johns Hopkins Clinical Compound Library demonstrates that certain drugs can alter the quaternary structure of an essential human protein. Human porphobilinogen synthase (HsPBGS) is an essential enzyme involved in heme biosynthesis; it exists as an equilibrium of high-activity octamers, low-activity hexamers, and alternate dimer configurations that dictate the stoichiometry and architecture of further assembly. Decreased HsPBGS activity is implicated in toxicities associated with lead poisoning and 5-aminolevulinate dehydratase (ALAD) porphyria, the latter of which involves hexamer-favoring HsPBGS variants. A medium-throughput native PAGE mobility-shift screen coupled with evaluation of hits as HsPBGS inhibitors revealed 12 drugs that stabilize the HsPBGS hexamer and inhibit HsPBGS activity in vitro. A detailed characterization of these effects is presented. Drug inhibition of HsPBGS in vivo by inducing hexamer formation would constitute an unprecedented mechanism for side effects. We suggest that small-molecule perturbation of quaternary structure equilibria be considered as a general mechanism for drug action and side effects.     

Custody and access assessors: Effects of background and experience on analogue case judgement.

Addressed some of the limitations inherent in the study by P. J. Caplan and J. Wilson (1990) regarding personal characteristics of custody and access (CA) assessors by evaluating levels of CA experience and clinician background characteristics for their effects on the number of strategies used to compensate for bias, analog case recommendation ratings, and additional information required to make a recommendation. 174 social workers, psychologists, and psychiatrists (39.7% male, mean age 46 yrs, mean clinical experience 14.2 yrs) completed self-report questionnaires. Clinicians who had more CA experience used a greater number of strategies to compensate for bias and required more additional information to make a recommendation on the case scenarios. Recommendation ratings of case scenarios were not affected by assessors' background characteristics. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Small noncleaved cell lymphoma associated with florid epithelioid granulomatous response. A clinicopathologic study of seven patients

Hypertension has its roots in childhood. Electrocardiographic, echocardiographic, and exercise testing in young patients point to early abnormalities of cardiovascular status in children with early hypertensive disease. Altered morphology of the cardiovascular system and vascular reactivity is also seen in the hypertensive or prehypertensive child. Perhaps investigation and preventive tactics may be best applied to the pediatric population.