A subunit interaction in chloroplast ATP synthase determined by genetic complementation between chloroplast and bacterial ATP synthase genes

F1F0-ATP synthases utilize protein conformational changes induced by a transmembrane proton gradient to synthesize ATP. The allosteric cooperativity of these multisubunit enzymes presumably requires numerous protein-protein interactions within the enzyme complex. To correlate known in vitro changes in subunit structure with in vivo allosteric interactions, we introduced the beta subunit of spinach chloroplast coupling factor 1 ATP into a bacterial F1 ATP synthase. A cloned atpB gene, encoding the complete chloroplast beta subunit, complemented a chromosomal deletion of the cognate uncD gene in Escherichia coli and was incorporated into a functional hybrid F1 ATP synthase. The cysteine residue at position 63 in chloroplast beta is known to be located at the interface between alpha and beta subunits and to be conformationally coupled, in vitro, to the nucleotide binding site > 40 A away. Enlarging the side chain of chloroplast coupling factor 1 beta residue 63 from Cys to Trp blocked ATP synthesis in vivo without significantly impairing ATPase activity or ADP binding in vitro. The in vivo coupling of nucleotide binding at catalytic sites to transmembrane proton movement may thus involve an interaction, via conformational changes, between the amino-terminal domains of the alpha and beta subunits.     

The Smoking Consequences Questionnaire-Adult: Measurement of smoking outcome expectancies of experienced smokers.

The original Smoking Consequences Questionnaire (SCQ; T. H. Brandon & T. B. Baker, 1991) measured college students' outcome expectancies for cigarette smoking. A version (SCQ-Adult) was needed for assessing expectancies in more typical, older, nicotine-dependent smokers. Two separate versions of the SCQ were developed and compared. Tests of construct validity provided greater support for the version comprising probability items over the version comprising subjective expected utility items. As expected, principal components analyses revealed a greater number of factors than the original SCQ suggesting that expectancies become more specific with smoking experience. All scales showed good reliability. Over the course of smoking cessation treatment, expectancies became less positive, especially for abstaining participants. Other validity tests also tended to be consistent with research on alcohol expectancies and with contemporary models of drug outcome expectancies. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Implementation of multipoint connections in an ATM switching network

This paper presents the problems in the implementation of multipoint connections at switching level using the example of an ATM switching network. By choosing the proper routeing mechanism and the appropriate architecture of the switching element, a switching network can gradually be adapted to an increasing share of multipoint traffic. The first section describes the problems with the handling of multipoint connections within a multiple stage connection oriented switching network. In particular this refers to the routeing of the cells through the switching network. Several alternatives on this issue are discussed. Both, the selected approach based on a differentiated self-routeing mechanism and the corresponding cell format are introduced. In the second part of this article several switch architectures are compared in respect of their multipoint capability. It is demonstrated that at present the most promising solution are switching elements based on the principle of central buffering. A single chip solution using this concept is employed in the presented switching network.     

Prejudice, stereotypes, and labeling effects: Sources of bias in person perception.

A preliminary study and 3 experiments compared predictions generated by contrasting models of how group labels bias person perception. An affective model assumed that how much perceivers like different groups mediates bias; a cognition model assumed that perceivers' beliefs regarding different groups mediates bias; and a third model assumed that both affect and cognition are necessary to mediate bias. Perceivers evaluated behavior samples provided by targets who were labeled as either rock music performers or child abusers in the preliminary study and the first 2 experiments; homosexuals or heterosexuals in the third experiment. In all studies, controlling for liking eliminated bias. The preliminary study and Study 3 also showed that controlling for beliefs about the groups eliminated bias. Structural equation modeling provided support for the affect model in Studies 1 and 2, and mixed support for the affect model and the cognition model in Study 3. These studies suggest an important role for affect in judgmental biases. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Three-week hepatitis B vaccination provides protective immunity

To determine whether a 3-week hepatitis B (HB) vaccination could achieve protective immunity, 89 healthy non-immunized young adults received three doses of 20 micrograms each of HBs antigen (GenHevac B, Pasteur) and were randomly assigned to schedule A (n = 44): two doses at day 0, one dose at day 21; or schedule B (n = 45): one dose at days 0, 10 and 21. Seroprotection rates (anti-HBs > or = 10 mIU ml-1) for groups A and B respectively were: 23 and 40% at day 21; and 77 and 91% at day 82 (not significant). Anti-HBs geometric mean titres were higher in group B than in group A (p < 0.05) at days 21 (6.4 versus 3.8) and 82 (77.6 versus 33.5). One year after primary vaccination, the seroprotection rate remained as high as 90% in the vaccinees of group B; after boosting all vaccinees had protective levels of anti-HBs antibodies. Thus 3-week HB vaccination with GenHevac B allowed early and durable protective immunity.     

An antigenic polysaccharide from Campylobacter coli serotype O:30. Structure of a teichoic acid-like antigenic polysaccharide associated with the lipopolysaccharide

A water-soluble antigenic polysaccharide of high M(r) associated with the lipopolysaccharide has been isolated from phenol-water extraction of cells of Campylobacter coli serotype O:30. The polysaccharide and oligosaccharide degradation products formed on O-dephosphorylation and by periodate oxidation followed by reduction have been investigated by one- and two-dimensional 1H, 13C, and 31P NMR. It is concluded that the antigenic polysaccharide has a teichoic acid-like structure with a poly-Ribitol phosphate, [5-Ribitol-1-P]n, backbone with side chains at O-2 of O-(6-deoxy-beta-D-talo-heptopyranosyl)-(1-->4)-(2-acetylamino-2-deoxy-beta-D- glucopyranosyl) units. The structure is unusual in Gram-negative bacteria and is unique in possessing 6-deoxy-D-talo-heptose as a constituent sugar. Evidence for the relationship of the antigenic polysaccharide to the lipopolysaccharide of low M(r) is discussed.     

Bioavailability of phenytoin acid and phenytoin sodium with enteral feedings

In the absence of E1B, the 289-amino acid product of human adenovirus type 5 13S E1A induces p53-independent apoptosis by a mechanism that requires viral E4 gene products (Marcellus, R.C., J.C. Teodoro, T. Wu, D.E. Brough, G. Ketner, G.C. Shore, and P.E. Branton. 1996. J. Virol. 70:6207-6215) and involves a mechanism that includes activation of caspases (Boulakia, C.A., G. Chen, F.W. Ng, J. G. Teodoro, P.E. Branton, D.W. Nicholson, G.G. Poirier, and G.C. Shore. 1996. Oncogene. 12:529-535). Here, we show that one of the E4 products, E4orf4, is highly toxic upon expression in rodent cells regardless of the p53 status, and that this cytotoxicity is significantly overcome by coexpression with either Bcl-2 or Bcl-XL. Conditional expression of E4orf4 induces a cell death process that is characterized by apoptotic hallmark features, such as externalization of phosphatidylserine, loss of mitochondrial membrane potential, cytoplasmic vacuolation, condensation of chromatin, and internucleosomal DNA degradation. However, the wide-spectrum inhibitor of caspases, tetrapeptide zVAD-fmk, does not affect any of these apoptogenic manifestations, and does not alter the kinetics of E4orf4-induced cell death. Moreover, E4orf4 expression does not result in activation of the downstream effector caspase common to most apoptosis-inducing events, caspase-3 (CPP32). We conclude, therefore, that in the absence of E1A, E4orf4 is sufficient by itself to trigger a p53-independent apoptosis pathway that may operate independently of the known zVAD-inhibitable caspases, and that may involve an as yet uncharacterized mechanism.