Effects of Micronutrients during Pregnancy and Early Infancy on Mental and Psychomotor Development

Spectacular progress has been made in the last decades in the global fight against deficiencies of iodine and vitamin A [1]. As a result, the number of people suffering from iodine deficiency has been reduced from about 1.5 billion in 1990 to about 0.5 billion now, almost entirely due to the introduction in many countries of what has been termed ‘universal salt iodization’. In addition, approximately one million child deaths may have been prevented between 1998 and 2000 by vitamin A supplementation [2]. The political and financial commitment that has allowed these achievements has been generated to a large extent by scientific studies that have shown the extent of human suffering caused by these deficiencies, and that have determined the potential health gains of interventions. Progress in eliminating deficiencies of other micronutrients, notably iron, has been much slower. About two billion people, or about one third of the human population, continue to suffer from iron deficiency. Iron supplementation programs have been advocated for infants and preschool children, largely because of concerns of possible adverse effects of iron deficiency on mental and motor development. Similar concerns were instrumental in establishing salt iodization programs. The questions that will be addressed in this chapter concern the extent to which a shortage of iodine and iron during fetal and infant development impairs mental development, and the extent to which this impairment can be redressed by increasing the intake of these micronutrients. First, the stages of brain development in the fetus and infant will be addressed, followed by an assessment of the timing of vulnerable periods when the brain of the fetus and infant is at high risk of exposure to an inadequate supply of iodine or iron. Where possible, the mechanisms involved will be discussed. Then, observational and intervention studies will be reviewed that have examined the effect of deficiencies of iodine or iron on mental development. Approximately half of the world’s population may be at risk of low zinc intake [3]. Given this high prevalence, inconclusive but mounting evidence that zinc deficiency during pregnancy may possibly impair the infant’s neurobehavioral development and immune function should also raise great concern [4–10]. However, because of space limitations, such effects and those of other micronutrients [11] will not be reviewed in the present report

Cortisol is transported by the multidrug resistance gene product P-glycoprotein.

The physiology of the multidrug transporter P-glycoprotein (Pgp) is still poorly understood. We now show evidence that cell lines with a high expression of Pgp display a reduced accumulation of cortisol and an ATP-dependent outward transport of the hormone. Cortisol efflux from Pgp negative cells does not have such an active component. Further we show that the steroid hormones cortisol, testosterone, and progesterone cause an immediate, dose-dependent increase of daunorubicin accumulation in Pgp overexpressing cells. These effects are particularly apparent for the more lipophilic steroids. These results demonstrate that Pgp may function as a transporter for cortisol and suggest a physiological role of the protein in steroid handling by organs such as the adrenal

Structural and torsional properties of the RAD51-dsDNA nucleoprotein filament

Human RAD51 is a key protein in the repair of DNA by homologous recombination. Its assembly onto DNA, which induces changes in DNA structure, results in the formation of a nucleoprotein filament that forms the basis of strand exchange. Here, we determine the structural and mechanical properties of RAD51-dsDNA filaments. Our measurements use two recently developed magnetic tweezers assays, freely orbiting magnetic tweezers and magnetic torque tweezers, designed to measure the twist and torque of individual molecules. By directly monitoring changes in DNA twist on RAD51 binding, we determine the unwinding angle per RAD51 monomer to be 45°, in quantitative agreement with that of its bacterial homolog, RecA. Measurements of the torque that is built up when RAD51-dsDNA filaments are twisted show that under conditions that suppress ATP hydrolysis the torsional persistence length of the RAD51-dsDNA filament exceeds that of its RecA counterpart by a factor of three. Examination of the filament's torsional stiffness for different combinations of divalent ions and nucleotide cofactors reveals that the Ca2+ ion, apart from suppressing ATPase activity, plays a key role in increasing the torsional stiffness of the filament. These quantitative measurements of RAD51-imposed DNA distortions and accumulated mechanical stress suggest a finely tuned interplay between chemical and mechanical interactions within the RAD51 nucleoprotein filament

Is there a vortex-glass transition in high-temperature superconductors?

We show that DC voltage versus current measurements of a YBCO micro-bridge in a magnetic field can be collapsed onto scaling functions proposed by Fisher, Fisher, and Huse, as is widely reported in the literature. We find, however, that good data collapse is achieved for a wide range of critical exponents and temperatures. These results strongly suggest that agreement with scaling alone does not prove the existence of a phase transition. We propose a criterion to determine if the data collapse is valid, and thus if a phase transition occurs. To our knowledge, none of the data reported in the literature meet our criterion.Comment: 4 pages, 4 figure

The Lyman-alpha forest of a Lyman Break Galaxy: VLT Spectra of MS1512-cB58 at z=2.724

The high redshift galaxy MS1512-cB58 (z=2.724, m_V=20.64) has been observed with the very efficient high resolution echelle spectrograph VLT/UVES. Although this is a very challenging observational program for a Southern hemisphere telescope (the galaxy is located at +36 deg declination), high resolution spectra (FWHM ~ 26 km/s) have revealed, with unprecedented detail along a galaxy sight line, the Lyman-alpha forest due to intervening clouds in the intergalactic medium (IGM). The mean depression D_A due to IGM absorption blueward of the galaxy Ly-alpha wavelength and the number density dn/dz of Ly-alpha clouds have been compared with equivalent results obtained for QSO sight lines at similar redshifts. Our results indicate a possible excess of absorption close to the galaxy. The mean depression at ~ 150 h_65^-1 Mpc comoving (Omega_m=0.3, Omega_Lambda=0.7) from the galaxy is D_A=0.36+/-0.03, to be compared with 0.22+/-0.04, expected from a best fit to QSO sight lines. In the same region (z=2.610), the number density of lines with HI column density in excess of 10^14 atoms/cm2 is also about 3 sigma larger than expected. This high density region is at least 60 h_65^-1 Mpc comoving wide, but the large Ly-alpha absorption of the galaxy itself prevents us from detecting a possible structure extending down to the galaxy. This excess of Ly-alpha clouds is suggestive of two possible scenarios. One is the presence of a super cluster of Ly-alpha clouds not associated with cB58. The other is a high density of gas associated with the environment of cB58. Indeed, a hint of the complexity of cB58 and possibly its environment is given by the huge velocity range (almost 1000 km/s) between the optical emission of star forming regions and UV absorption of its interstellar medium.Comment: Accepted for publication in Ap

Прибыльность предприятия и стратегия ее обеспечения

Целью статьи является системное развитие теоретических, научно-методических и практических положений обеспечения прибыльности предприятия с помощью специально разработанных стратегий, которые направлены на повышение конкурентоспособности и эффективности развития предприятия, обоснование путей улучшения управления прибыльностью предприятий на основе различных исследований

Resistivity due to low-symmetrical defects in metals

The impurity resistivity, also known as the residual resistivity, is calculated ab initio using multiple-scattering theory. The mean-free path is calculated by solving the Boltzmann equation iteratively. The resistivity due to low-symmetrical defects, such as an impurity-vacancy pair, is calculated for the FCC host metals Al and Ag and the BCC transition metal V. Commonly, 1/f noise is attributed to the motion of such defects in a diffusion process.Comment: 24 pages in REVTEX-preprint format, 10 Postscript figures. Phys. Rev. B, vol. 57 (1998), accepted for publicatio

Phase Transition in the Two-Dimensional Gauge Glass

The two-dimensional XY gauge glass, which describes disordered superconducting grains in strong magnetic fields, is investigated, with regard to the possibility of a glass transition. We compute the glass susceptibility and the correlation function of the system via extensive numerical simulations and perform the finite-size scaling analysis. This gives strong evidence for a finite-temperature transition, which is expected to be of a novel type.Comment: 5pages, 3 figures, revtex, to appear in Phys. Rev.

Positive Quantum Brownian Evolution

Using the independent oscillator model with an arbitrary system potential, we derive a quantum Brownian equation assuming a correlated total initial state. Although not of Lindblad form, the equation preserves positivity of the density operator on a restricted set of initial states