Financial strain, received support, anticipated support, and depressive symptoms in the People's Republic of China.

The purpose of this study is to examine the interface between financial strain, informal received economic support, informal anticipated financial support, and psychological distress in later life. Data provided by a large probability sample of older adults in the People's Republic of China reveal that the relationship between financial difficulty and psychological distress is stronger for older adults who receive more economic assistance. However, the results involving anticipated support are in the opposite direction. More specifically, the association between financial problems and psychological distress is lower for older adults who believe that others stand ready to help in the future should the need arise. A detailed theoretical rationale is developed to explain these results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

固态继电器为电动汽车电池监测提供便利

电动汽车常被喻作“归来的孩子”，因为这项技术在多年前进入市场后便一直沉寂，直至最近才再次活跃起来。其实，电动汽车早于1835年首次于美国出现，到1899年，纽约市接近90％的出租车都是由电力驱动。然而，当电力启动器和内燃机变得完善时，电动汽车的使用就迅速衰退。随着如今对环境保护的关注，由燃烧碳氢化合物造成的污染，加之汽油成本高升的影响，再次     

The roles of conserved carboxylate residues in IMP dehydrogenase and identification of a transition state analog

IMP dehydrogenase (IMPDH) catalyzes the oxidation of IMP to XMP with the concomitant reduction of NAD+; the enzyme is activated by K+. This reaction is the rate-limiting step in de novo guanine nucleotide biosynthesis. In order to identify functionally important residues in IMPDH, including those involved in substrate and K+ binding, we have mutated 11 conserved Asp and Glu residues to Ala in Escherichia coli IMPDH. The values of kcat, Km, and Ki for GMP, XMP, mizoribine 5'-monophosphate (MMP), and beta-methylene-tiazofurin adenine dinucleotide (TAD) were determined. Five of these mutations caused a significant change (>/=10-fold) in one of these parameters. The Asp248 --> Ala mutation caused 100-fold decrease in the value of kcat and a 25-fold increase in the value of Kii for TAD; these observations suggest that Asp248 is in the NAD+ binding site. The Asp338 --> Ala mutation caused a 600-fold decrease in the value of kcat, but only a 5-10-fold increase in the values of Km for IMP and Kis for IMP analogs, suggesting that Asp338 may be involved in acid-base catalysis as well as IMP binding. The remaining three residues, Asp13, Asp50, and Glu469, appear to be involved in K+ activation; these residues may be ligands at one or more K+ binding sites. Interestingly, changes in the values of Ki for MMP correlate with changes in kcat/KmKm of IMPDH, while no such correlation is observed for GMP, XMP, and TAD. This observation indicates that MMP is a transition state analog for the IMPDH reaction.     

Relationship between the genomic organization and the overlapping embryonic expression patterns of the zebrafish dlx genes

To understand the relationship between the expression and the genomic organization of the zebrafish dlx genes, we have determined the genomic structure of the dlx2 and dlx4 loci. This led to the identification of the zebrafish dlx1 and dlx6 genes, which are closely linked to dlx2 and dlx4, respectively. Therefore, the inverted convergent configuration of Dlx genes is conserved among vertebrates. Analysis of the expression patterns of dlx1 and dlx6 showed striking similarities to those of dlx2 and dlx4, respectively, the genes to which they are linked. Furthermore, the expression patterns of dlx3 and dlx7, which likely constitute a third pair of convergently transcribed genes, are indistinguishable. Thus, the overlapping expression patterns of linked Dlx genes during embryonic development suggest that they share cis-acting sequences that control their spatiotemporal expression. The evolutionary conservation of the genomic organization and combinatorial expression of Dlx genes in distantly related vertebrates suggest tight control mechanisms that are essential for their function during development.     

A case of paraquat poisoning and subsequent fatality presenting to an emergency department

Paraquat (1,1'-dimethyl-4,4'-dipyridylium) is an herbicide associated with both accidental and intentional ingestion, leading to severe and often fatal toxicity. Prognosis is largely dependent on the amount of paraquat absorbed. Rapid identification of the symptoms of paraquat toxicity (burns or ulceration at the site of ingestion or injection, acute respiratory distress, and renal failure) can facilitate early treatment intervention to limit absorption. We report a case of a 71-year-old man with a suicidal ingestion of paraquat 2 days prior to presentation. Serum paraquat levels, time elapsed since ingestion, and clinical symptoms all indicated poor prognosis. The patient developed severe respiratory distress and progressive renal failure, and died 6 days after admission to the hospital.     

Tyrosine kinases: modular signaling enzymes with tunable specificities

Cytoplasmic tyrosine kinases are composed of modular domains; one (SH1) has catalytic activity, the other two (SH2 and SH3) do not. Kinase specificity is largely determined by the binding preferences of the SH2 domain. Attaching the SH1 domain to a new SH2 domain, via protein-protein association or mutation, can thus dramatically change kinase function.     

COPD: using nutrition to prevent respiratory function decline

Close to three-fourths of patients with chronic obstructive pulmonary disease (COPD) suffer from weight loss. Identifying a single cause for this is difficult, as several factors-including chronic mouth breathing, dyspnea, aerophagia, certain medications, and depression-often act in concert. Malnutrition can exacerbate symptoms of COPD by decreasing ventilatory muscle strength, exercise tolerance, and immunocompetence, and by increasing the risk of depression and anxiety. Goals of nutrition intervention are to prevent or reverse malnutrition without worsening the disease process and to improve respiratory function, thereby reducing morbidity and delaying mortality. Recommendations for intake of fats, carbohydrates, protein, and water must be individualized.