Predicting posttraumatic growth in breast cancer survivors.

Wide variability exists with respect to how breast cancer survivors respond to common psychological and psychosocial challenges of their disease, ranging from posttraumatic stress disorder to posttraumatic growth. This cross-sectional study examined contextual, disease-related, and intraindividual predictors of posttraumatic growth in 224 randomly selected breast cancer survivors. A series of hierarchical regression analyses found that age at diagnosis, marital status, employment, education, perceived intensity of disease, and active coping accounted for 34%, 35%, and 28% of the variance in growth in relationships with others, new possibilities, and appreciation for life. These findings suggest that a more comprehensive model of growth will be helpful in understanding the various factors that play a role in breast cancer survivors' perception of psychological and psychosocial growth. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

DECOUPLING ACTUATORS WITHH∞ROBUST CONTROL FOR ACTIVELY ISOLATING VIBRATING MACHINES

A feedback controller designed to minimise the vibration transmitted to a flexible beam from a vibrating machine via two active isolation mounts is described. The state–space equation for the mechanical structure is obtained by performing modal analysis on the associated conservative structure.H_∞control methods are used to derive a decoupled (diagonal) controller which provides robustness against unmodeled high-order frequency dynamics and optimises the performance in terms of the frequency response shaping of the modal accelerations. The performances of the decoupled controller were found to be similar to those of the coupled (global) one.     

High D-glucose does not affect binding of alpha-tocopherol to human erythrocytes

The role of alpha-tocopherol uptake system in human erythrocyte in the uptake of plasma alpha-tocopherol has been suggested. However no information is available on alpha-tocopherol uptake activity of human erythrocytes in the presence of high levels of D-glucose which is known to lead to pathological alterations in different cells including human erythrocytes. Therefore, in order to examine the effect of D-glucose on the binding of alpha-tocopherol to human erythrocytes, the binding characteristics of alpha-tocopherol to these cells were established first. Binding of [3H]alpha-tocopherol to human erythrocytes was both saturable and specific. Scatchard analysis of alpha-tocopherol binding to these cells showed the presence of two independent classes of binding sites with widely different affinities. The high affinity binding sites had a dissociation constant (Kd1) of 90 nM with a binding capacity (n1) of 900 sites per cell, whereas the low affinity binding sites had a dissociation constant (Kd2) of 5.2 microM and a binding capacity (n2) of 105,400 sites per cell. Trypsin treatment abolished all the alpha-tocopherol binding activity. Competition for the binding of alpha-tocopherol to human erythrocytes was effective with other homologues of alpha-tocopherol (beta-tocopherol, gamma-tocopherol and delta-tocopherol) and their potency was almost equal to alpha-tocopherol itself. The order of preference was alpha-tocopherol > beta-tocopherol > or = gamma-tocopherol > or = delta-tocopherol. Incubation of human erythrocytes with various concentrations of D-glucose did not affect alpha-tocopherol uptake activity. Our data demonstrate the presence of an alpha-tocopherol uptake system in human erythrocytes and that the alpha-tocopherol uptake activity is not modulated by the presence of D-glucose.     

Exploring the Role of Genetic Variability and Lifestyle in Oxidative Stress Response for Healthy Aging and Longevity

Oxidative stress is both the cause and consequence of impaired functional homeostasis characterizing human aging. The worsening efficiency of stress response with age represents a health risk and leads to the onset and accrual of major age-related diseases. In contrast, centenarians seem to have evolved conservative stress response mechanisms, probably derived from a combination of a diet rich in natural antioxidants, an active lifestyle and a favorable genetic background, particularly rich in genetic variants able to counteract the stress overload at the level of both nuclear and mitochondrial DNA. The integration of these factors could allow centenarians to maintain moderate levels of free radicals that exert beneficial signaling and modulator effects on cellular metabolism. Considering the hot debate on the efficacy of antioxidant supplementation in promoting healthy aging, in this review we gathered the existing information regarding genetic variability and lifestyle factors which potentially modulate the stress response at old age. Evidence reported here suggests that the integration of lifestyle factors (moderate physical activity and healthy nutrition) and genetic background could shift the balance in favor of the antioxidant cellular machinery by activating appropriate defense mechanisms in response to exceeding external and internal stress levels, and thus possibly achieving the prospect of living a longer life.     

Does the application of ground force set the energetic cost of cross-country skiing?

We tested whether the rate at which force is applied to the ground sets metabolic rates during classical-style roller skiing in four ways: 1) by increasing speed (from 2.5 to 4.5 m/s) during skiing with arms only, 2) by increasing speed (from 2.5 to 4.5 m/s) during skiing with legs only, 3) by changing stride rate (from 25 to 75 strides/min) at each of three speeds (3.0, 3.5, and 4.0 m/s) during skiing with legs only, and 4) by skiing with arms and legs together at three speeds (2.0-3.2 m/s, 1.5 degrees incline). We determined net metabolic rates from rates of O2 consumption (gross O2 consumption - standing O2 consumption) and rates of force application from the inverse period of pole-ground contact [1/tp(arms)] for the arms and the inverse period of propulsion [1/tp(legs)] for the legs. During arm-and-leg skiing at different speeds, metabolic rates changed in direct proportion to rates of force application, while the net ground force to counteract friction and gravity (F) was constant. Consequently, metabolic rates were described by a simple equation (metab = F . 1/tp . C, where metab is metabolic rates) with cost coefficients (C) of 8.2 and 0.16 J/N for arms and legs, respectively. Metabolic rates predicted from net ground forces and rates of force application during combined arm-and-leg skiing agreed with measured metabolic rates within +/-3. 5%. We conclude that rates of ground force application to support the weight of the body and overcome friction set the energetic cost of skiing and that the rate at which muscles expend metabolic energy during weight-bearing locomotion depends on the time course of their activation.     

Renal adaptation to dietary sodium restriction in moderate renal failure resulting from chronic glomerular disease

The renal response to sodium restriction was evaluated, and the concurrent changes of the plasma levels of aldosterone (ALDO) and atrial natriuretic peptide (ANP), in healthy patients (NOR), in normotensive patients with non-nephrotic chronic glomerulonephritis and normal renal function (GN), and in patients with glomerulonephritis and moderate renal failure (GFR, 41 +/- 4 mL/min; CRF). The three groups were studied for 1 wk after changing from a normal-sodium diet (NSD, 235 mEq NaCl/day) to a low-sodium diet (LSD, 35 mEq NaCl/day). All patients reached a steady sodium balance within the 4th and 5th day of LSD with an analogous cumulative loss of sodium. After salt restriction, the fractional urinary sodium excretion diminished by the same extent in the three groups, whereas the fractional free-water generation, measured during water diuresis, did not vary in NOR and markedly decreased in GN and CRF. Plasma levels of ALDO were similar in all groups at NSD and similarly increased during LSD. In GN and CRF, as compared to NOR, ANP levels were higher at NSD and decreased by a minor extent during LSD. Notably, in GN and CRF, but not in NOR, the attainment of the new sodium balance after sodium restriction was preceded by a significant parallel reduction of blood pressure and GFR; the GFR decline was secondary to a major decrement of RPF so that filtration fraction (FF) increased. It was concluded that in NOR, distal tubular effects of ANP and ALDO account for the attainment of sodium balance during LSD. As a difference, both GN and CRF patients achieve the new sodium balance primarily through hemodynamic changes: the renal hypoperfusion secondary to a decrease in blood pressure that diminishes the filtered load of sodium, and the increase of FF that enhances the proximal tubular sodium reabsorption. This abnormal response seems related to both the minor suppression of ANP and the increased salt-sensitivity of blood pressure that are likely the result of the presence of volume expansion.     

Analysis of multi-degree of freedom strongly non-linear mechanical systems with random input: Part II: equivalent linear system with random matrices and power spectral density matrix

We present a method for estimating the (power spectral density) PSD matrix of the stationary response of lightly damped randomly excited multi-degree of fredom mechanical systems with strong non-linear asymmetrical restoring forces. The PSD matrix is defined as the mean value of the PSD matrix response of an equivalent linear system (ELS) whose damping and stiffness matrices depend on non-linear vibration modes of the associated conservative system, the frequencies and modes shapes being amplitude dependent. Based on a generalized van der Pol transformation and using a stochastic averaging principle, as developed in a companion paper, a stationary probability density function for the amplitude process is derived to characterize the ELS fully. Some possible simplifications of the method, such as modal reduction and/or local linearization, are also discussed. The results obtained are in good agreement with those of direct numerical simulations taking two typical examples.     

Structure and Activity of the Thermophilic Tryptophan-6 Halogenase BorH

Flavin-dependent halogenases carry out regioselective aryl halide synthesis in aqueous solution at ambient temperature and neutral pH using benign halide salts, making them attractive catalysts for green chemistry. BorH and BorF, two proteins encoded by the biosynthetic gene cluster for the chlorinated bisindole alkaloid borregomycin A, are the halogenase and flavin reductase subunits of a tryptophan-6-halogenase. Quantitative conversion of l -tryptophan (Trp) to 6-chlorotryptophan could be achieved using 1.2 mol % BorH and 2 mol % BorF. The optimal reaction temperature for Trp chlorination is 45 °C, and the melting temperatures of BorH and BorF are 48 and 50 °C respectively, which are higher than the thermal parameters for most other halogenases previously studied. Steady-state kinetic analysis of Trp chlorination by BorH determined parameters of k_cat=4.42 min⁻¹, and K_M of 9.78 μm at 45 °C. BorH exhibits a broad substrate scope, chlorinating and brominating a variety of aromatic substrates with and without indole groups. Chlorination of Trp at a 100 mg scale with 52 % crude yield, using 0.2 mol % BorH indicates that industrial scale biotransformations using BorH/BorF are feasible. The X-ray crystal structure of BorH with bound Trp provides additional evidence for the model that regioselectivity is determined by substrate positioning in the active site, showing C6 of Trp juxtaposed with the catalytic Lys79 in the same binding pose previously observed in the structure of Thal.     

Microwave cancer imaging exploiting magnetic nanoparticles as contrast agent

In this paper, a microwave technique for breast cancer imaging is presented. The approach is based on the use of magnetic nanoparticles as contrast agent to induce a nonnull magnetic contrast selectively localized within the tumor. This allows us to face cancer imaging as the reconstruction of a magnetic contrast from the corresponding scattered field. To extract, from the measured data the contribution due to the magnetic contrast, i.e., the signal meaningful for cancer imaging, the approach exploits the possibility of modulating the magnetic response of magnetic nanoparticles by means of a polarizing magnetic field. The achievable reconstruction capabilities and the robustness against uncertainties on the electric features of the surrounding electric scenario are assessed by means of numerical examples.