Kinetics of interaction of HIV fusion protein (gp41) with lipid membranes studied by real-time AFM imaging

One of the most important steps in the process of viral infection is a fusion between cell membrane and virus, which is mediated by the viral envelope glycoprotein. The study of activity of the glycoprotein in the post-fusion state is important for understanding the progression of infection. Here we present a first real-time kinetic study of the activity of gp41 (the viral envelope glycoprotein of human immunodeficiency virus—HIV) and its two mutants in the post-fusion state with nanometer resolution by atomic force microscopy (AFM). Tracking the changes in the phosphatidylcholine (PC) and phosphatidylcholine–phosphatidylserine (PC:PS) membrane integrity over one hour by a set of AFM images revealed differences in the interaction of the three types of protein with zwitterionic and negatively charged membranes. A quantitative analysis of the slow kinetics of hole formation in the negatively charged lipid bilayer is presented. Specifically, analysis of the rate of roughness change for the three types of proteins suggests that they exhibit different types of kinetic behavior.     

Everyday work investigations for safety

A key theme in safety is the investigation and improvement of work processes and conditions. This is built on a tradition of studying accidents, but there is growing interest in the investigation of everyday work. Researchers have started using terms such as success, normal and everyday work investigations, but behind these can be different activities. This paper makes explicit some considerations behind investigations of everyday work, how these considerations shape an investigation, and how they reflect different schools of thought. These considerations can be used as an aid for designing everyday work investigations for safety and serve as a first step towards critical reflection on investigating everyday work.     

Convergences among psychoanalytic and cognitive-behavioral theories of depression.

Discusses 2 types of depression based on disruptions of (1) interpersonal relatedness or (2) self-esteem, and considers the nature, etiology, and treatment of depression based on the phenomenology of the issues that cause individuals to become depressed. The interpersonal perspective of S. Arieti and J. Bemporad (1980), the object relations perspective of J. Bowlby (see record 1988-16459-001), and the psychoanalytic ego psychology and cognitive developmental theory perspective of S. J. Blatt (1992) are compared and contrasted with each other and with the cognitive-behavioral perspective of A. T. Beck (1983). Areas of agreement and differences among these 4 theoretical positions are discussed in terms of their implications for treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of motive for helping, recipient's inability to reciprocate, and sex on devaluation of the recipient's competence.

Tested the prediction that motive base will interact with reciprocation such that greater superiority in perceived competence will occur following nonreciprocation than following reciprocation of efficacy-motivated helpers. It was hypothesized that this effect would be qualified by the helper's motivation for helping, the evaluative attribute in question, and the helper's set. 60 male and 60 female undergraduates were asked to imagine that during the preceding weekend they had successfully rescued a boatload of children. For half of the Ss, the scenario emphasized efficacy-motivating helping; for the other half, it emphasized empathy-motivated helping. Ss were then put to work on the "easier" of 2 "randomly assigned" word-forming tasks, whereas their same-sex partner (a confederate) worked on the "harder" task. Once Ss reached their quota they were invited to send their excess letters to the still-struggling co-worker; all did. In return, the confederate attempted successfully or unsuccessfully to share his or her earnings. As predicted, the efficacy-motivated helpers, unlike their empathy-motivated counterparts, rated themselves as more competent than, but not more sociable than, the recipient who was unable to reciprocate. Weak support was found for the prediction that these differences in perceived competence would largely apply to male helpers. (34 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Microstructure of Hardened Cement Paste—A New Interpretation

Morphological features of hydrated portland cement paste exhibited on carefully polished surfaces have been critically examined using backscatter mode scanning electron microscopy. A new interpretation and classification of such features is proposed. The microstructure is seen to consist of distinct grains of the order of 10 μm and larger ("phenograins") set in a cellular groundmass of smaller particles and pores. Most of the phenograins are dense pseudomorphs of the larger cement grains, but some are large calcium hydroxide crystals, and in some cements a few may represent inert filler grains added to the cement. The phenograins that are pseudomorphs of cement particles may be solid, gapped, or hollow; and, at a given age, various stages of hydration are represented in different grains. While many pseudomorph phenograins consist of a simple core of unhydrated material surrounded by a uniform shell of hydration product, more complex and irregular structures are also found. Relationships between these features and earlier classifications of cement hydration product particles are discussed, and implications with respect to difficulties in image analysis of hardened cement paste are examined.     

Supercomputers — past,present, prospects

In the fourth decade of the computer age, supercomputers are attracting increasingly more attention.     

Fredholm integral equation of the Laser Intensity Modulation Method (LIMM): Solution with the polynomial regularization and L-curve methods

The Laser Intensity Modulation Method (LIMM) is widely used for the determination of the spatial distribution of polarization in polar ceramics and polymers, and space charge in non-polar polymers. The analysis of experimental data requires a solution of a Fredholm integral equation of the 1st kind. This is an ill-posed problem that has multiple and very different solutions. One of the more frequently used methods of solution is based upon Tikhonov regularization. A new method, the Polynomial Regularization Method (PRM), was developed for solving the LIMM equation with an 8th degree polynomial using smoothing to achieve a stable and optimal solution. An algorithm based upon the L-curve method (LCM) was used for the prediction of the best regularization parameter. LIMM data were simulated for an arbitrary polarization distribution and were analyzed using PRM and LCM. The calculated distribution function was in good agreement with the simulated polarization distribution. Experimental polarization distributions in a poorly poled sample of polyvinylidene fluoride (PVDF) and in a LiNbO₃ bimorph, and space charge in polyethylene were analyzed. The new techniques were applied to the analysis of 3-dimensional polarization distributions.     

A gene essential to brain growth and development maps to the distal arm of rat chromosome 12

Studies were undertaken to determine the stability of nitrobenzodiazepines and their 7-amino metabolites in water and blood. At 22 degrees C nitrazepam and clonazepam were stable in sterile fresh blood containing preservative over 28 days, whereas 25% of flunitrazepam was degraded. At 37 degrees C all three drugs were substantially lost over 9 h (29-51%). There was only a small loss observed for the 7-amino metabolites and no substantial amounts of parent drug and 7-amino metabolite were degraded in water under these conditions. In the absence of preservative substantial amounts (25-50%) of parent drugs were lost in fresh blood over 10 days at 22 degrees C. In bacterially-contaminated postmortem blood all three drugs were completely degraded over 8 h at 22 degrees C with almost all drug completely converted to the respective 7-amino metabolite. These metabolites were also partially degraded (10-20%) over 45 h at 22 degrees C. All 3 nitrobenzodiazepines were stable in blood stored for up to 24 months at -20 degrees C, or 4 degrees C over 10 months. Their respective 7-amino metabolites were, however, relatively unstable at -20 degrees C with a significant loss (29%) after 2 months. At 4 degrees C a 21% loss occurred after 1 month. Freeze/thawing was found not to affect the concentration of nitrobenzodiazepine and 7-amino metabolites. These results show that the nitrobenzodiazepines and their metabolites are unstable chemically and metabolically in blood. We advise that blood collected for the purpose of nitrobenzodiazepine determinations should be preserved with sodium fluoride, stored at -20 degrees C and assayed as soon as practicable, preferably within a week of collection.     

Individuality and relatedness: Evolution of a fundamental dialectic.

Western psychologies have traditionally given greater importance to self-development than to interpersonal relatedness, stressing the development of autonomy independence, and identity as central factors in the mature personality. In contrast, women, many minority groups, and non-Western societies have generally placed greater emphasis on issues of relatedness. This article traces the individualistic bias and recent challenges to this view. It is proposed that evolutionary pressures of natural selection result in 2 basic developmental lines: interpersonal relatedness and self-definition, which interact in a dialectical fashion. An increasingly mature sense of self is contingent on interpersonal relationships: conversely, the continued development of increasingly mature interpersonal relationships is contingent on mature self-definition. Conclusions include implications for social policy and for facilitating more balanced development of both dimensions in all members of society. (PsycINFO Database Record (c) 2010 APA, all rights reserved)