Sex ratios among Canadian liveborn infants of mothers from different countries

Background:

There has been much discussion about whether female feticide occurs in certain immigrant groups in Canada. We examined data on live births in Ontario and compared sex ratios in different groups according to the mother’s country or region of birth and parity.

Methods:

We completed a population-based study of 766 688 singleton live births between 2002 and 2007. We used birth records provided by Ontario Vital Statistics for live births in the province between 23 and 41 weeks’ gestation. We categorized each newborn according to the mother’s country or region of birth, namely Canada (n = 486 599), Europe (n = 58 505), South Korea (n = 3663), China (n = 23 818), Philippines (n = 15 367), rest of East Asia (n = 18 971), Pakistan (n = 18 018), India (n = 31 978), rest of South Asia (n = 20 695) and other countries (n = 89 074). We calculated male:female ratios and 95% confidence intervals (CIs) for all live births by these regions and stratified them by maternal parity at the time of delivery (0, 1, 2 or ≥ 3).

Results:

Among infants of nulliparous women, the male:female ratio was about 1.05 overall. As parity increased, the ratio remained unchanged among infants of Canadian-born women. In contrast, the male:female ratio was significantly higher among infants of primiparous women born in South Korea (1.20, 95% CI 1.09–1.34) and India (1.11, 95% CI 1.07–1.15) than among infants of Canadian-born primiparous women. Among multiparous women, those born in India were significantly more likely than Canadian-born women to have a male infant (parity 2, ratio 1.36, 95% CI 1.27–1.46; parity ≥ 3, ratio 1.25, 95% CI 1.09–1.43).

Interpretation:

Our study of male:female ratios in Ontario showed that multiparous women born in India were significantly more likely than multiparous women born in Canada to have a male infant.Although there are some myths about correctly guessing the sex of a fetus,¹ modern-day prenatal ultrasound enables the identification of whether a fetus is a boy or girl with 99% accuracy.² There has been much discussion about whether female fetuses are at higher risk of pregnancy termination than male fetuses in certain ethnic groups. In India, a study of data from the National Family Health Survey for 265 516 births showed a sharp increase in the male:female ratio among second-order births when the firstborn was a girl, and no significant increase when the firstborn was a boy.³ The authors attributed this trend to the practice of selective abortion of female fetuses. A recent editorial⁴ and news item⁵ in CMAJ suggested that female feticide may also be occurring in Canada.⁶ Rather than using live-birth statistics, the Canadian study cited in CMAJ used data from the 2001 and 2006 Canada Census long-form questionnaires, which were completed by 20% of the population and relied on self-reporting of additional information, including the number of family members in a given household.We used contemporary data on live births in Ontario, Canada’s most populous and ethnically diverse province, and compared sex ratios among infants of Canadian-born women with sex ratios in different immigrant groups. We focused on immigrant groups from countries purported to have the highest rates of preference for a son following the birth of one or more daughters.^3–6 We determined whether the male:female ratio increased with increasing parity in certain immigrant groups, as has been previously suggested.^3,6     

GSAFold: a new application of GSA to protein structure prediction

The folding process defines three‐dimensional protein structures from their amino acid chains. A protein's structure determines its activity and properties; thus knowing such conformation on an atomic level is essential for both basic and applied studies of protein function and dynamics. However, the acquisition of such structures by experimental methods is slow and expensive, and current computational methods mostly depend on previously known structures to determine new ones. Here we present a new software called GSAFold that applies the generalized simulated annealing (GSA) algorithm on ab initio protein structure prediction. The GSA is a stochastic search algorithm employed in energy minimization and used in global optimization problems, especially those that depend on long‐range interactions, such as gravity models and conformation optimization of small molecules. This new implementation applies, for the first time in ab initio protein structure prediction, an analytical inverse for the Visitation function of GSA. It also employs the broadly used NAMD Molecular Dynamics package to carry out energy calculations, allowing the user to select different force fields and parameterizations. Moreover, the software also allows the execution of several simulations simultaneously. Applications that depend on protein structures include rational drug design and structure‐based protein function prediction. Applying GSAFold in a test peptide, it was possible to predict the structure of mastoparan‐X to a root mean square deviation of 3.00 Å. Proteins 2012; © 2012 Wiley Periodicals, Inc.     

Field testing, gene flow assessment and pre-commercial studies on transgenic Solanum tuberosum spp. tuberosum (cv. Spunta) selected for PVY resistance in Argentina

Solanum tuberosum ssp. tuberosum (cv. Spunta) was transformed with a chimeric transgene containing the Potato virus Y (PVY) coat protein (CP) sequence. Screening for PVY resistance under greenhouse conditions yielded over 100 independent candidate lines. Successive field testing of selected lines allowed the identification of two genetically stable PVY-resistant lines, SY230 and SY233, which were further evaluated in field trials at different potato-producing regions in Argentina. In total, more than 2,000 individuals from each line were tested along a 6-year period. While no or negligible PVY infection was observed in the transgenic lines, infection rates of control plants were consistently high and reached levels of up to 70-80%. Parallel field studies were performed in virus-free environments to assess the agronomical performance of the selected lines. Tubers collected from these assays exhibited agronomical traits and biochemical compositions indistinguishable from those of the non-transformed Spunta cultivar. In addition, an interspecific out-crossing trial to determine the magnitude of possible natural gene flow between transgenic line SY233 and its wild relative Solanum chacoense was performed. This trial yielded negative results, suggesting an extremely low probability for such an event to occur.     

The mycobacterial thioredoxin peroxidase can act as a one-cysteine peroxiredoxin

Thioredoxin peroxidase (TPx) has been reported to dominate the defense against H(2)O(2), other hydroperoxides, and peroxynitrite at the expense of thioredoxin (Trx) B and C in Mycobacterium tuberculosis (Mt). By homology, the enzyme has been classified as an atypical 2-C-peroxiredoxin (Prx), with Cys(60) as the "peroxidatic" cysteine (C(P)) forming a complex catalytic center with Cys(93) as the "resolving" cysteine (C(R)). Site-directed mutagenesis confirms Cys(60) to be C(P) and Cys(80) to be catalytically irrelevant. Replacing Cys(93) with serine leads to fast inactivation as seen by conventional activity determination, which is associated with oxidation of Cys(60) to a sulfinic acid derivative. However, in comparative stopped-flow analysis, WT-MtTPx and MtTPx C93S reduce peroxynitrite and react with TrxB and -C similarly fast. Reduction of pre-oxidized WT-MtTPx and MtTPx C93S by MtTrxB is demonstrated by monitoring the redox-dependent tryptophan fluorescence of MtTrxB. Furthermore, MtTPx C93S remains stable for 10 min at a morpholinosydnonimine hydrochloride-generated low flux of peroxynitrite and excess MtTrxB in a dihydrorhodamine oxidation model. Liquid chromatography-tandem mass spectrometry analysis revealed disulfide bridges between Cys(60) and Cys(93) and between Cys(60) and Cys(80) in oxidized WT-MtTPx. Reaction of pre-oxidized WT-MtTPx and MtTPx C93S with MtTrxB C34S or MtTrxC C40S yielded dead-end intermediates in which the Trx mutants are preferentially linked via disulfide bonds to Cys(60) and never to Cys(93) of the TPx. It is concluded that neither Cys(80) nor Cys(93) is required for the catalytic cycle of the peroxidase. Instead, MtTPx can react as a 1-C-Prx with Cys(60) being the site of attack for both the oxidizing and the reducing substrate. The role of Cys(93) is likely to conserve the oxidation equivalents of the sulfenic acid state of C(P) as a disulfide bond to prevent overoxidation of Cys(60) under a restricted supply of reducing substrate.     

Should tendon and aponeurosis be considered in series?

Fibres, aponeuroses, and tendons are often considered mechanically "in series" in skeletal muscles. This notion has led to oversimplified calculations of fibre forces from tendon forces, to incorrect derivations of constitutive laws for aponeuroses, and to misinterpretations of the recovery of elastic energy in stretch-shortening cycles of muscles. Here, we demonstrate theoretically, using examples of increasing complexity, that tendon and aponeurosis are not in series in a muscle fibre-aponeurosis-tendon complex. We then demonstrate that assuming the tendon and aponeurosis to be in series can lead to the appearance of mechanical work creation in these passive viscoelastic structures, a result that is mechanically impossible. Finally, we explain the mechanical role of the incompressible muscle matrix in force transmission from fibres to aponeuroses and tendon, and emphasize that incompressibility necessitates the introduction of extra forces necessary to maintain this constraint. Unfortunately, this requirement eliminates, for all but the simplest cases, a theoretical approach of muscle modeling based on intuitive free-body diagrams.     

Solvent-induced lysozyme gels: effects of system composition and temperature on structural and dynamic characteristics

The gelation process of lysozyme in water/tetramethylurea in the presence of salt was investigated as a function of temperature and system composition by rheology, infrared spectroscopy, and microcalorimetry. Times and temperatures of gelation were determined from the variation of the storage (G') and loss (G') moduli. It was found that gelation times follow exponential decays with both protein and tetramethylurea (TMU) concentrations and with temperature. The activation energy for the overall process shows a linear dependence on TMU mass fraction. A strongly increased beta-sheet content and reduced alpha-helix occur with the increase of TMU concentration in the binary solvent. Also, a linear decrease of lysozyme denaturation temperature and enthalpy on TMU concentration is found for the TMU mass fraction up to 0.5, above which no denaturation signal can be detected.     

Antioxidant effect of diphenyl diselenide against sodium nitroprusside (SNP) induced lipid peroxidation in human platelets and erythrocyte membranes: an in vitro evaluation

An in vitro evaluation on the antioxidant effect of diphenyl diselenide (PhSe)(2), an organochalcogenide, against sodium nitroprusside (SNP)-induced lipid peroxidation (LPO) was conduced. Human platelets and erythrocyte membranes (ghosts), as well as rat brain homogenates (S(1)), were pre-incubated with different concentrations of SNP (0-10 microM). All SNP concentrations tested significantly increased LPO in human platelets and S(1). Platelets were more sensitive to SNP-induced peroxidative damage when compared to S(1). SNP 10 microM decreased glutathione peroxidase (GPx) activity and did not affect glutathione reductase (GR) and catalase (CAT) activities in human platelets. However, ghosts were insensitive to SNP-induced LPO and no changes on GPx, GR and CAT activities were observed. Diphenyl diselenide significantly protected human platelets against SNP-induced LPO and recovered GPx inactivation. This effect was more evident at (PhSe)(2) concentrations above 2 microM. The presented results indicate that (PhSe)(2) exerts protective effects on SNP-induced oxidative damage in human blood components and in rat brain. These phenomena seem to be related to its thiol peroxidase-like activity and to a possible direct interaction with SNP and derivatives. Based on our results and on literature, diphenyl diselenide can be pointed as a promising antioxidant molecule.