NMR studies on the conformation of the CD4 36-59 peptide bound to HIV-1 gp120

A peptide containing residues 36-59 of the human CD4 receptor includes most of the residues thought to be involved in binding the HIV surface glycoprotein, gp120. This peptide was synthesized and inhibited the binding of gp120 to soluble CD4. NMR relaxation experiments indicated that the peptide was in fast exchange between the free and gp120-bound states. Transferred NOESY NMR showed a number of long-range NOEs, from the gp120-bound state, between residues 38, 40, 45, 48, and 49 of the peptide. NMR evidence also suggested that the Phe43 in the peptide, which corresponds to a critical residue in CD4 for the binding of gp120, makes intimate contact with gp120. The Tr-NOESY cross-peak intensities provided proton-proton distance constraints on the conformation of the gp120-bound peptide. The distance constraints were used in simulated annealing, and a set of 20 very similar structures was obtained for the central region of the gp120-bound peptide. Residues 42-49 of the peptide formed a loop with the side chain of Phe43 pointing away from the rest of the peptide. This Phe43 ring points away from the protein surface in two structures of the amino-terminal domain of CD4 found by X-ray crystallography. Differences in the conformation of CD4 in the two crystal forms suggest that the 36-59 region might be flexible. The NMR data on the 36-59 CD4 peptide predicts a gp120-bound conformation different from either of the CD4 crystal forms in the absence of gp120.     

Acute choroidal ischemia as a complication of photocoagulation

Acute choroidal vascular insufficiency as a complication of photocoagulation has been little noticed. In 17 eyes of 16 patients photocoagulated with either xenon or argon sources for proliferative sickle cell retinopathy, gray lesions of the fundus developed peripheral to the photocoagulation sites. Histologic examination of similar gray lesions produced in monkeys showed necrosis and atrophy of the outer half of the retina. Intense photocoagulation of the human fundus, even with smaller spot sizes, may occlude a choroidal artery, producing separate gray lesions of distinctive shape. The lesions in both the patients and the monkeys progressed to granular hyperpigmentation by two to three weeks after photocoagulation.     

Macular and perimacular vascular remodelling sickling haemoglobinopathies

The posterior pole vasculature of 100 patients with different sickling haemoglobinopathies was studied prospectively over a period of three years. Various abnormalities of the posterior pole vasculature were seen in 29 per cent of the patients. Continuous remodelling of the macular and perimacular vasculature occurred. Visual acuity was variably affected and sometimes remained intact.     

Discriminatory function of serum proteins in liver and biliary tract diseases

In 104 patients with acute virus hepatitis, chronic hepatitides, cirrhoses, fatty livers and biliary diseases with partial and complete obstructive jaundice, respectively, IgG, IgA, IgD, beta1A- and beta1E-globulin, cholinesterase, total protein, and albumin, in 45 of these patients additionally prealbumin, retinol binding protein, thymol turbidity test were determined as well as an electrophoretic separation of the serum was performed. 11 persons with healthy liver served as control group. According to the results of univariate and multivariate variance analyses with following test of redundance (test for indispensability) and analysis of discriminance with calculations of reclassification IgD, beta1E-globulin and retinol binding protein were identified as not evident or redundant. Electrophoresis and thymol turbidity test give sufficient basis informations and can further be recommended for orienting examinations. Immune globulinogrammes from IgB, IgA and IgM are suitable as so-called mesenchyma tests particularly for controls of the course. Prealbumin and cholinesterase prove to be the most sensitive parameter of synthesis, whereas albumin and beta1A-globulin possess a high prognostic evidence.     

Development and validation of a real-time SAFT-UT system for inservice inspection of LWRs

A three-year program at the Pacific Northwest Laboratory is underway to move the synthetic aperture focusing technology from the laboratory into the field. This is a report of the first year's activities that concentrated on conducting the needed engineering for a field system. In addition, the data acquisition portion of the system was completed so that data can be collected in the field with subsequent laboratory processing. The field system specifications are given and some SAFT results are shown.     

Wetting by sodium at high temperatures in pure vapour atmosphere

The wetting angle of sodium on different pure metals (Ni, Ta, Mb, Mo, W), alloys (stainless steel 304L, Inconel 600, RTG 36, TZM) and oxides (Feldmühle E37, Degussa AL23, sapphire, ZrO₂, Y₂O₃) was measured in the temperature range from 520 to 720°C. A new measurement method was applied consisting of a combination of the classical sessile drop with a gas controlled heat pipe. The method is especially suited for high temperatures where the previous methods are impracticable because of excessive sodium evaporation. It has furthermore the advantage that the measurements are made under pure sodium vapour. In the temperature range mentioned all investigated materials are well wetted. The maximum measured wetting angle is 7.5°. The wetting angles are nearly independent from temperature, but they show a time-dependency consisting in general of a rapid initial decrease and a reaching of the equilibrium value after about 1 hour.     

Effects of material incentives on classroom learning over a four-week period.

Assessed the effects of material incentives on the learning of spelling words in typical classrooms over a 4-wk period. 14 4th grade classes with a total of 330 students participated. Seven classes were randomly assigned to a material incentive condition, and 7 to a normal, or social incentive, condition. Classroom means were used as the unit of analysis. Ss who were offered material incentives learned significantly more spelling words than did Ss not offered material rewards. Ss in the material incentive condition learned an average of about 61/2 new words during each week's lessons; Ss who were offered only social incentives learned an average of about 3 new words during each week. The substantial effects of the material incentives continued throughout the 4 wks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Investigation of the corrosion mechanism in tantalum-lithium high temperature heat pipes by ion analysis

The corrosion mechanism in S.G.S. tantalum/lithium heat pipes operated at 1600 °C was investigated by metallography and ion analysis. The following results were obtained: (1) The wall-material in the condensation zone is deoxidized and grain growth of S.G.S. tantalum follows. (2) The oxygen is carried away by the liquid lithium film towards the heating zone where it is concentrated by fractional distillation of lithium. (3) A liquid Li-O-Y-Ta phase forms which locally attacks the wall material in the heating zone through intergranular corrosion. (4) Failure of the heat pipe occurs through complete perforation of the heat pipe in the corrosion zone.