Selective interactions among the multiple connexin proteins expressed in the vertebrate lens: the second extracellular domain is a determinant of compatibility between connexins

Gap junctions are collections of intercellular channels composed of structural proteins called connexins (Cx). We have examined the functional interactions of the three rodent connexins present in the lens, Cx43, Cx46, and Cx50, by expressing them in paired Xenopus oocytes. Homotypic channels containing Cx43, Cx46, or Cx50 all developed high conductance. heterotypic channels composed of Cx46 paired with either Cx43 or Cx50 were also well coupled, whereas Cx50 did not form functional channels with Cx43. We also examined the functional response of homotypic and heterotypic channels to transjunctional voltage and cytoplasmic acidification. We show that all lens connexins exhibited sensitivity to cytoplasmic acidification as well as to voltage, and that voltage-dependent closure of heterotypic channels for a given connexin was dramatically influenced by its partner connexins in the adjacent cell. Based on the observation that Cx43 can discriminate between Cx46 and Cx50, we investigated the molecular determinants that specify compatibility by constructing chimeric connexins from portions of Cx46 and Cx50 and testing them for their ability to form channels with Cx43. When the second extracellular (E2) domain in Cx46 was replaced with the E2 of Cx50, the resulting chimera could no longer form heterotypic channels with Cx43. A reciprocal chimera, where the E2 of Cx46 was inserted into Cx50, acquired the ability to functionally interact with Cx43. Together, these results demonstrate that formation of intercellular channels is a selective process dependent on the identity of the connexins expressed in adjacent cells, and that the second extracellular domain is a determinant of heterotypic compatibility between connexins.     

Improving graduate student performance in cognitive assessment: The saga continues.

Investigators have concluded that excessive numbers of errors in test administration and scoring are routinely committed by both graduate students and practicing psychologists. Developing new methods for teaching assessment is viewed as a major means of improving competency. Unlike previous studies, this investigation examined the impact of both lecture and laboratory interventions designed to improve graduate student performance in assessment. Interventions consisted of weekly lecture quizzes and a variety of laboratory interventions. The results suggest that the interventions used can significantly improve students' lecture and laboratory performance when compared with controls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Post and core reconstruction for fixed prosthodontic restoration

If the previous restorative therapy or dental caries has resulted in substantial loss of tooth structure, the abutment teeth for fixed prosthodontic restorations require a core reconstruction or a post and core. Small dentin defects can be restored with bonded cores; more extensive dentin defects that are often accompanied by previous endodontic treatment generally require additional support for the core material. A direct procedure with a bonded post is a viable treatment method. The decision to use either light-conducting all-ceramic zirconium or titanium as a post material depends on the aesthetic requirements present. The indications for a cast post and core as an indirect procedure for prosthodontic reconstructions appear to be decreasing. The learning objective of this article is to review the past and current post and core materials and techniques. Indications for core reconstruction with vital teeth and posts and cores for pulpless teeth are discussed.     

Morphological analysis of poly(o-methoxyaniline) thin-films deposited by spin coating technique

Morphological study of conducting polymer thin films obtained by spin coating is reported. Poly(o-methoxyaniline) films were deposited onto glass substrates and analyzed by profilometry and atomic force microscopy (AFM). It is shown that final thickness is correlated by a power law with spin speed with a solution concentration varying coefficient and that surface roughness decreases with increasing spin speed.     

Energy Dissipation at the Slug Nose and the Modeling of Solids Transport in Intermittent Flow

It is shown, by means of Lagrangian momentum and power balances across the slug nose in slug flow, that the power dissipated due to sudden expansion of the fluid in the film immediately downstream of the slug nose is greater than the power lost due to viscous action at the pipe wall but that it may not be large enough to materially aid particle transport. This has the implication that sand transport in intermittent flow may be considered as transport in a hybrid flow of hydraulic conveying and stratified flow when the length of the mixing section at the slug nose is short compared to the length of the slug body.     

Nutritive expectancies mediate cholecystokinin's suppression-of-intake effect.

In previous studies of cholecystokinin's (CCK's) effect on consumption, physical features (e.g., taste, texture, and odor) of test meals were confounded with the nutritive expectancies elicited by those features. To separately assess the role of these two factors in supporting CCK's suppression-of-intake effect, we varied the caloric expectancies elicited by a flavored test solution, while holding constant its actual caloric density, as well as all other unconditioned stimulus features. On alternate days for a 12-day period, hungry rats drank grape or orange Kool-Aid (noncaloric) mixed with a caloric 5% ethanol solution; on the other days, they drank the alternate flavor mixed with plain water. In a subsequent choice test between the flavored solutions without ethanol, the ethanol-associated flavor (Ef) was preferred over the water-associated flavor (Wf). Two days later, the rats were injected with either cholecystokinin octapeptide (CCK-8; ip, 2 μg/kg) or isotonic saline, and then given access to their Ef or their Wf for 1 hr. Consumption of the Ef was supressed by CCK-8; intake of the Wf was unaffected. These results suggest that CCK-8's effectiveness in suppressing intake of a test meal may be treated not to the unconditioned stimulus features of that meal but to the nutritive expectations elicited by those features. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bioprocess applications of model-based estimation techniques

The last decade has seen the development of a number of approaches for estimating those variables which are difficult to measure on-line in industrial process situations. Whilst a range of techniques is available, a common element is the use of process knowledge in the form of a system model. In the case of bioprocess systems, although a large range of models has been presented in the literature, their use in estimation schemes on an industrial scale has been limited. A number of reasons can be identified for their low level of utilisation. Of particular significance is the uncertainty which exists in quantifying system performance and the process-model mismatch which inevitably results. The level of ‘pre-defined model’ uncertainty, together with the knowledge gained during the course of the fermentation, serves to dictate estimator structure. The paper considers a range of estimation strategies and contrasts, through industrial applications, their performance characteristics and utility.     

The mathematics of motif combination and their use for functional simulation

The concept of Motif Combination was introduced in the French Automotive industry's R&W standard. There has however been no formal mathematical theory for the technique of motif combination. This paper sets out to develop this theory. The main result of the paper is a set of four properties that the motif combination rules must satisfy in order to have certain desirable metrological properties.Motif methods may well provide useful techniques which complement rather than replace the traditional approach based on a mean line. It was found that many functional problems could be simulated very efficiently using motif methods. Examples of functional simulation via motif combination are illustrated in the paper.     

L'impact des sympt?mes somatiques dans l'évaluation de la dépression chez une population gériatrique.

Studied the relationship among age, physical health status, and psychic and somatic symptoms of depression among elderly adults. Human Ss: 318 male and female Canadian older adults (aged 65–102 yrs). Information on sociodemographic factors and health status was obtained using the Older American Research Scale, French version, by R. Lefran?ois et al (1988). A French version by P. Bourque and D. Beaudette (1982) of the Beck Depression Inventory was also used. The results were evaluated according to each S's sex, age, institutionalized residence status, and health status. Statistical tests were used. (English abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)