pH dependency of kinetic parameters and reaction mechanism of beef liver catalase.

The pH-dependence of the kinetic parameters in H2O2 decomposition by beef liver catalase was investigated. At pH 7.0, the ternary complex (ESS) decomposition rate was about 100 times faster than ESS formation (42 microM H2O2), and the value of the Michaelis constant was 0.025 M. From ethanol competition experiments, two different proton dissociation constants of the enzyme (pKe1 = 5.0, pKes2 = 5.9) were obtained for the binding of first and second H2O2 molecules. Another pKa value (pKes1) of 4.2 was obtained from the pH dependence of overall rate constant (ko). The reaction mechanism of catalase was discussed in relation to these ionizable groups.     

Reproductive health status, knowledge, and access to health care among female migrants in Shanghai, China

As the largest labour flow in human history, the recent rise in migration in China has opened up unprecedented opportunities for millions of Chinese to rearrange their lives. At the same time, this process has also posed great challenges to Chinese migrants, especially female migrants, who not only face a bias against 'outsiders' but also have a greater need for reproductive health-related services in their migratory destinations. Based on data collected via multiple sources in Shanghai, China's largest metropolis, this study profiles the changing characteristics of female migrants, presents data on self-reported symptoms of reproductive health-related problems and knowledge on reproductive health issues, compares maternal and child health measures between migrants and local residents, and examines factors related to reproductive health knowledge and migrants' access to health care in urban China. Results of this study show a relatively low level of self-reported reproductive health problems among female migrants, coupled with a relatively high level of ignorance in knowledge related to STD. Both self-reported health status and knowledge of reproductive health are related to migrants' educational attainment and length of stay in the urban destination. This study also finds ample evidence that female migrants' access to urban health care is limited by a number of institutional barriers.     

A complementation method for functional analysis of mammalian genes

Our progress in understanding mammalian gene function has lagged behind that of gene identification. New methods for mammalian gene functional analysis are needed to accelerate the process. In yeast, the powerful genetic shuffle system allows deletion of any chromosomal gene by homologous recombination and episomal expression of a mutant allele in the same cell. Here, we report a method for mammalian cells, which employs a helper-dependent adenoviral (HD-Ad) vector to synthesize small hairpin (sh) RNAs to knock-down the expression of an endogenous gene by targeting untranslated regions (UTRs). The vector simultaneously expresses an exogenous version of the same gene (wild-type or mutant allele) lacking the UTRs for functional analysis. We demonstrated the utility of the method by using PRPF3, which encodes the human RNA splicing factor Hprp3p. Recently, missense mutations in PRPF3 were found to cause autosomal-dominant Retinitis Pigmentosa, a form of genetic eye diseases affecting the retina. We knocked-down endogenous PRPF3 in multiple cell lines and rescued the phenotype (cell death) with exogenous PRPF3 cDNA, thereby creating a genetic complementation method. Because Ad vectors can efficiently transduce a wide variety of cell types, and many tissues in vivo, this method could have a wide application for gene function studies.     

Effects of spironolactone and eprosartan on cardiac remodeling and angiotensin-converting enzyme isoforms in rats with experimental heart failure

Angiotensin-converting enzyme (ACE)-2 is a newly described enzyme with antagonistic effects to those of the classical ACE (ACE-1). Both ANG II and aldosterone play an important role in the pathophysiology of congestive heart failure (CHF) and in the adverse cardiac remodeling during its development. In this study, we examined the effects of experimental CHF induced by an aortocaval fistula (ACF) and of its treatment with ANG II and aldosterone inhibitors on the relative levels of ACE-1 and ACE-2. We also compared the effects of spironolactone, an aldosterone antagonist, and eprosartan, an ANG II receptor antagonist, on heart hypertrophy and fibrosis in rats with ACF. Spironolactone (15 mg x kg(-1) x day(-1) ip, via minipump) or eprosartan (5 mg x kg(-1) x day(-1) ip, via minipump) was administered into rats with ACF for 14 and 28 days. Specific antibodies were used to determine the protein levels of myocardial ACE-1 and ACE-2. ACF increased the cardiac levels of ACE-1 and decreased those of ACE-2. Heart-to-body weight ratio significantly increased from 0.30 +/- 0.004% in sham-operated controls to 0.50 +/- 0.018% and 0.56 +/- 0.044% (P < 0.001) in rats with ACF, 2 and 4 wk after surgery, respectively, in association with increased plasma levels of aldosterone. The area occupied by collagen increased from 2.33 +/- 0.27% to 6.85 +/- 0.65% and 8.03 +/- 0.93% (P < 0.01), 2 and 4 wk after ACF, respectively. Both spironolactone and eprosartan decreased cardiac mass and collagen content and reversed the shift in ACE isoforms. ACF alters the ratio between ACE isoforms in a manner that increases local ANG II and aldosterone levels. Early treatment with both ANG II and aldosterone antagonists is effective in reducing this effect. Thus ACE isoform shift may represent an important component of the development of cardiac remodeling in response to hemodynamic overload, and its correction may contribute to the beneficial therapeutic effects of renin-angiotensin-aldosterone system inhibitors.     

miR-152 regulates the proliferation and differentiation of C2C12 myoblasts by targeting <Emphasis Type="Italic">E2F3</Emphasis>

The development of skeletal muscle is a complex process involving the proliferation, differentiation, apoptosis, and changing of muscle fiber types in myoblasts. Many reports have described the involvement of microRNAs in the myogenesis of myoblasts. In this study, we found that the expression of miR-152 was gradually down-regulated during myoblast proliferation, but gradually up-regulated during the differentiation of myoblasts. Transfection with miR-152 mimics restrained cell proliferation and decreased the expression levels of cyclin E, CDK4, and cyclin D1, but promoted myotube formation and significantly increased the mRNA expression levels of MyHC, MyoD, MRF4, and MyoG in C2C12 myoblasts. However, treatment with miR-152 inhibitors promoted cell proliferation and restrained differentiation. Moreover, over-expression of miR-152 significantly decreased E2F3 production in C2C12 myoblasts. A luciferase assay confirmed that miR-152 could bind to the 3′ UTR of E2F3. In conclusion, this study showed that miR-152 inhibited proliferation and promoted myoblast differentiation by targeting E2F3.     

Determination of the parameters of the hot plasma formed during the implosion of wire arrays from time-resolved X-ray spectra of H- and He-like ions

A system for recording X-ray ion spectra by means of a spherical crystal with the subsequent transformation of the X-ray spectrum into an optical image recorded with the help of an optical streak camera is described. A computer code intended to recover the plasma parameters from the intensities of spectral lines of H- and He-like ions of some chemical elements (z = 6–29) is developed. Results of experiments on the determination of the parameters of hot plasma formed during the implosion of nested aluminum wire arrays at the S-300 high-current generator are presented.     

Heterogeneous set of cell wall teichoic acids in strains of <Emphasis Type="Italic">Bacillus subtilis</Emphasis> VKM B-760 and VKM B-764

Cell walls of Bacillus subtilis VKM B-760 and VKM B-764 are characterized by heterogeneous composition of teichoic acids. Polymer I with structure -6)-β-D-Galp-(1→1)-sn-Gro-(3-P-, polymer II with structure -6)-α-D-Glcp-(1→1)-sn-Gro-(3-P-, and a small amount of unsubstituted 1,3-poly(glycerol phosphate) were detected in strain VKM B-760. Strain VKM B-764 contains an analogous set of teichoic acids, but a characteristic feature of polymer II is the presence of disubstituted glycerol residue with α-glucopyranose localization in the integral chain at C-1 hydroxyl and β-glucopyranose as a side branch at C-2 hydroxyl (polymer III): -6)-α-D-Glcp-(1→1)-[β-D-Glcp-(1→2)]-sn-Gro-(3-P-. The structures of polymer I in bacilli and polymer III in Gram-positive bacteria are described for the first time. Teichoic acids were studied by chemical methods and on the basis of combined analysis of one-dimensional ¹H-, ¹³C-, and ³¹P-NMR spectra, homonuclear two-dimensional ¹H/¹H COSY, TOCSY, and ROESY, and heteronuclear two-dimensional ¹H/¹³C gHSQC- and HMQC-TOCSY experiments. Simultaneous presence of several different structure teichoic acids in the bacillus cell walls as well as chemotaxonomical perspectives of the application of these polymers as species-specific markers for members of the Bacillus genus is discussed.