T-type calcium channels facilitate insulin secretion by enhancing general excitability in the insulin-secreting beta-cell line, INS-1

The present study addresses the function of T-type voltage-gated calcium channels in insulin-secreting cells. We used whole-cell voltage and current recordings, capacitance measurements, and RIA techniques to determine the contribution of T-type calcium channels in modulation of electrical activity and in stimulus-secretion coupling in a rat insulin secreting cell line, INS-1. By employing a double pulse protocol in the current-clamp mode, we found that activation of T-type calcium channels provided a low threshold depolarizing potential that decreased the latency of onset of action potentials and furthermore increased the frequency of action potentials, both of which are abolished by administration of nickel chloride (NiCl2), a selective T-type calcium channel blocker. Moreover application of high frequency stimulation, as compared with low frequency stimulation, caused a greater change in membrane capacitance (deltaCm), suggesting higher insulin secretion. We demonstrated that glucose stimulated insulin secretion in INS-1 is reduced dose dependently by NiCl2. We conclude that T-type calcium channels facilitate insulin secretion by enhancing the general excitability of these cells. In light of the pathological effects of both hypo and hyperinsulinemia, the T-type calcium channel may be a therapeutic target.     

Verbal interaction in families of normal and expressive-language-delayed children.

Developmental expressive language disorder (ELD) is a condition characterized by a delay in the development of expressive language compared with receptive language and IQ. Conditions that might contribute to the origins or maintenance of ELD are poorly understood. Unusual verbal interactions between parents and ELD children might be implicated in the origins of ELD or might represent parental reactivity to the child's limited expressive skills. We compared verbal interactions in the homes of 28-month-old ELD children, and 17-month-old normal children matched on expressive ability with the ELD children. We analyzed frequencies of major pragmatic categories of parent and child verbal behavior as well as sequential relations involving those categories. Pragmatic interactions in the ELD families were substantially similar to those in the families of the normal younger children and different from those in the older normal children. A measure of the structural complexity of maternal speech (MLU) did not differ across the groups. These results indicate that pragmatic language interactions in the families of ELD children are determined largely by the children's level of expressive ability rather than by their age or receptive abilities. In this regard, the child directed speech of parents of ELD children cannot be considered deviant and cannot be implicated in the etiology of ELD. The sensitivity of parents to their child's level of expressive ability suggests the need for refinement in current hypotheses concerning child directed speech. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assessment of research needs for oil recovery from heavy-oil sources and tar sands

We have reviewed and evaluated the U.S. programs on oil recovery from heavy oil sources and tar sands. These studies were performed in order to provide an independent assessment of research areas that affect the prospects for oil recovery from these sources. This paper summarizes our findings and research recommendations.     

Age and schooling effects on emergent literacy and early reading skills.

This study examined the effects of age and schooling on emergent literacy and early reading skills of 337 children from low-income backgrounds. Children were followed longitudinally from the end of Head Start to the end of 1st grade. A subset of the sample (n?=?183) was followed through the end of 2nd grade. The oldest children in preschool and kindergarten had significantly stronger emergent literacy skills than classmates who were younger by 10 months. These differences did not translate to differences in reading skill at the end of 1st or 2nd grade. Children who began school a year earlier than same-age peers outperformed these peers on measures of both emergent literacy skills and early reading skills. The impact of a year of schooling on emergent literacy skills was 1.7 times greater than the impact of other processes associated with age. The impact of a year of schooling on early reading was 4.3 times stronger than the effect of age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Accelerating language development through picture book reading: Replication and extension to a videotape training format.

G. J. Whitehurst et al (see record 1989-02401-001) taught mothers specific interactive techniques to use when reading picture books with their preschool-age children. This intervention program, called dialogic reading, produced substantial effects on preschool children's language development. However, the costs of one-on-one training limit the widespread use of dialogic reading techniques. In this study the authors aimed to replicate and extend the results of the original study of dialogic reading by developing and evaluating an inexpensive videotape training package for teaching dialogic reading techniques. Mothers were randomly assigned to receive no training, traditional direct training, or videotape training. Results supported the conclusions of Whitehurst et al: Dialogic reading had powerful effects on children's language skills and indicated that videotape training provided a cost-effective, standardized means of implementing the program. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two-stage liquefaction of a subbituminous coal

The two-stage conversion of a subbituminous coal has been investigated using an autoclave reactor system. The overall performance of the reaction is found to be determined by the effectiveness of the first-stage operation and by the method of sequencing of the stages. The initial thermal products can undergo condensation reactions which render them unresponsive to subsequent catalytic conversion and which increase the light gas yield. This can occur during the first stage reaction, if there is limited capacity for free-radical stabilization, and upon storage and/or thermal cycling between stages. The latter effects are circumvented by operating the two stages in immediate sequence. Condensation is also reduced by increasing the solvent quality and the solvent:coal ratio. The presence of a catalyst during thermal decomposition of coal can greatly improve conversion and product stability even at short reaction time and can reduce constraints on solvent quality. The more feasible approaches to improving first-stage operation appear to be in controlling the solvent composition and in employing hydrogenation catalysts.     

Assessment of limitations and potentials for improvement in deep desulfurization through detailed kinetic analysis of mechanistic pathways

Utilizing an improved method for the assignment of the rate constants to the complicated network of reaction pathways in the hydrodesulfurization (HDS) of polyaromatic sulfur compounds (PASCs), new understanding has been obtained concerning the intrinsic limitations to achieving the new distillate fuels standards. Establishing the relative rates for hydrogenation of the parent sulfur compound and its desulfurized products, and considering thermodynamic limitations on hydrogenated intermediates are critical to these improved kinetics. With this new approach, it has been possible to more accurately assess the differences in performance of different catalysts such as Co–MoS_x/Al₂O₃, Ni–MoS_x/Al₂O₃ and analogous catalysts supported on carbons, the basic causes of selectivity change with temperature, and the mechanistic consequences of inhibitors on the HDS product distributions. Ni promoted catalysts were found to possess much higher hydrogenation activities than comparable Co promoted catalysts. Carbon supported catalysts appear to have potential for HDS at high temperatures. Inhibition by H₂S affects both hydrogenation and direct sulfur extraction HDS routes, but, secondary hydrogenation of desulfurized aromatic products was found to be the most sensitive to inhibition. Naphthalene inhibits all hydrogenation reactions but has little effect on direct HDS.