Supplementation of Vitamin E, Vitamin C, and Zinc Attenuates Oxidative Stress in Burned Children: A Randomized, Double-Blind, Placebo-Controlled Pilot Study

The aim of this study was to investigate the effect of supplementation of vitamin E, vitamin C, and zinc on the oxidative stress in burned children. In a prospective double-blind placebo-controlled pilot study, 32 patients were randomized as no supplementation (n = 15) or antioxidant supplementation (n = 17) groups. Supplementation consisted of the antioxidant mixture of vitamin C (1.5 times upper intake level), vitamin E (1.35 times upper intake level), and zinc (2.0 times recommended dietary allowance) administered during 7 days starting on the second day of admittance into the hospital. Energy requirement was calculated by the Curreri equation, and protein input was 3.0 g/kg of ideal body mass index (percentile 50 degrees). Total antioxidant capacity of plasma and malondialdehyde were used to monitor oxidative stress. The time of wound healing was evaluated as the main clinical feature. Patients (age 54.2 +/- 48.9 months, 65.6% males), who exhibited 15.5 +/- 6.7% of total burn area, showed no differences in age and sex, when compared with controls. Intake of the administered antioxidants was obviously higher in treated subjects (P = .005), and serum differences were confirmed for vitamin E and C, but not for zinc (P = .180). There was a decrease in lipid peroxidation (malondialdehyde level) (P = .006) and an increase in vitamin E concentrations in the antioxidant supplementation group (P = .016). The time of wound healing was lower in the supplemented group (P < .001). The antioxidant supplementation through vitamin E and C and the mineral zinc apparently enhanced antioxidant protection against oxidative stress and allowed less time for wound healing. (J Burn Care Res 2009;30:859-866)

Low dose of fine particulate matter (PM2.5) can induce acute oxidative stress, inflammation and pulmonary impairment in healthy mice

Air pollution is associated with morbidity and mortality induced by respiratory diseases. However, the mechanisms therein involved are not yet fully clarified. Thus, we tested the hypothesis that a single acute exposure to low doses of fine particulate matter (PM2.5) may induce functional and histological lung changes and unchain inflammatory and oxidative stress processes. PM2.5 was collected from the urban area of Sao Paulo city during 24 h and underwent analysis for elements and polycyclic aromatic hydrocarbon contents. Forty-six male BALB/c mice received intranasal instillation of 30 mu L of saline (CTRL) or PM2.5 at 5 or 15 mu g in 30 mu L of saline (P5 and P15, respectively). Twenty-four hours later, lung mechanics were determined. Lungs were then prepared for histological and biochemical analysis. P15 group showed significantly increased lung impedance and alveolar collapse, as well as lung tissue inflammation, oxidative stress and damage. P5 presented values between CTRL and P15: higher mechanical impedance and inflammation than CTRL, but lower inflammation and oxidative stress than P15. In conclusion, acute exposure to low doses of fine PM induced lung inflammation, oxidative stress and worsened lung impedance and histology in a dose-dependent pattern in mice.

Serotonin and Sensitivity to Trauma-Related Exposure in Selective Serotonin Reuptake Inhibitors-Recovered Posttraumatic Stress Disorder

Background: Selective serotonin reuptake inhibitors (SSRIs) are first-line treatments for posttraumatic stress disorder (PTSD). Serotonergic (5HT) attenuation of stress sensitivity is postulated from SSRIs` effects in other anxiety disorders, and we studied this in PTSD. Methods: Ten patients with PTSD fully recovered on SSRIs (Clinical Global Impression Scale-I 1 and 2) were enrolled in the study. Patients were tested on two occasions I week apart; in each session, they received a drink containing large neutral amino acids (LNAAs) either with (sham tryptophan depletion [STD], control) or without (acute tryptophan depletion [ATD]) tryptophan. At 5.5 hours after the drink, subjects were exposed to a trauma-related exposure challenge. Self-reports of PTSD (visual analogue scales [VAS] and the Davidson Trauma Scale [DTSI), anxiety (Spielberger State Inventory [STAI] Form Y-1), and mood (Profile of Mood States [POMS]) were obtained. Heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure were also measured. Results: The trauma-related exposure challenge induced anxiety on both days, with more marked responses on the ATD day according to VAS, DTS, POMS, and DBP (p < .05). A trend of significance (.1 > p >.05) was observed for STAI Form Y-1, HR, and SBP. Conclusions: These data demonstrate that ATD accentuates responses to trauma-related stimuli in SSRI-recovered PTSD. They also suggest that SSRI-induced increases in serotonin function restrain PTSD symptoms, especially under provocation, supporting a role for serotonin in mediating stress resilience.

Effect of academic psychological stress in post-graduate students: The modulatory role of cortisol on superoxide release by neutrophils

Experimental and clinical evidence shows that neutrophils play an important role in the mechanism of tissue injury in immune complex diseases through the generation of reactive oxygen species. In this study, we examined the influence of academic psychological stress in post-graduate students on the capacity of their blood neutrophils to release superoxide when stimulated by immune complexes bound to nonphagocytosable surfaces and investigated the modulatory effect of cortisol on this immune function. The tests were performed on the day before the final examination. The state-trait anxiety inventory questionnaire was used to examine whether this stressful event caused emotional distress. In our study, the psychological stress not only increased plasma cortisol concentration, but it also provoked a reduction in superoxide release by neutrophils. This decrease in superoxide release was accompanied by diminished mRNA expression for subunit p47(phox) of the phagocyte superoxide-generating nicotinamide adenine dinucleotide phosphate-oxidase. These inhibitory effects were also observed by in vitro exposure of neutrophils from control volunteers to 10(-7) M hydrocortisone, and could be prevented by the glucocorticoid receptor antagonist RU-486. These results show that in a situation of psychological stress, the increased levels of cortisol could inhibit superoxide release by neutrophils stimulated by IgG immune complexes bound to nonphagocytosable surfaces, which could attenuate the inflammatory state.

Effects of Cold Stress, Corticosterone and Catecholamines on Phagocytosis in Mice: Differences between Resting and Activated Macrophages

Objective: We subjected mice to acute cold stress and studied the effect on phagocytosis by peritoneal macrophages mediated by 3 types of phagocytic receptors: Fc gamma, complement receptors 3 (CR3) and mannose and beta-glucan receptors. Methods: Mice were subjected to a cold stress condition (4 C for 4 h), and then peritoneal macrophages were harvested and phagocytosis assays performed in vitro. Results: We found a striking difference between resting and lipopolysaccharide (LPS)-activated macrophages (by intraperitoneal injection of LPS 4 days before the stress experiment): for resting macrophages cold stress caused a decrease in phagocytosis mediated by Fc gamma or mannose receptors, while for activated macrophages we observed an increase in phagocytosis by the 3 types of receptors. These effects were associated with an increase in plasma concentrations of corticosterone and catecholamines following the cold stress. In order to verify whether these hormone changes could account for the observed effects on phagocytosis, we performed in vitro assays by incubating macrophages harvested from nonstressed animals with these hormones for 4 h at 37 degrees C and measuring their phagocytic capacity. The following experiments were done: (a) with resting (nonactivated) macrophages; (b) with macrophages previously activated in vitro by incubation with LPS; (c) with macrophages previously activated in vivo by intraperitoneal injection of mice with LPS, 4 days before harvesting the cells. We found that for resting macrophages, corticosterone decreased phagocytosis mediated by Fc gamma and mannose and beta-glucan receptors, but catecholamines had no effect. For macrophages activated either in vivo or in vitro, catecholamines caused an increase in phagocytosis (excluding mannose receptors) while corticosterone had no effect. Conclusion: The above findings suggest that stress can regulate phagocytosis in different ways, depending on the kind of phagocytic receptor involved, the level of stress hormones and the physiological state of the macrophages. Copyright (C) 2010 S. Karger AG, Basel

GABAergic mediation of stress-induced secretion of corticosterone and oxytocin, but not prolactin, by the hypothalamic paraventricular nucleus

The hypothalamus-pituitary-adrenal axis (HPA) participates in mediating the response to stressful stimuli. Within the HPA, neurons in the medial parvocellular region of paraventricular nucleus (PVN) of the hypothalamus integrate excitatory and inhibitory signals triggering secretion of corticotropin-releasing hormone (CRH), the main secretagogue of adrenocorticotropic hormone (ACTH). Stressful situations alter CRH secretion as well as other hormones, including prolactin and oxytocin. Most inputs to the PVN are of local origin, half of which are GABAergic neurons, and both GABA-A and GABA-B receptors are present in the PVN. The objective of the present study was to investigate the role of GABA-A and GABA-B receptors in the PVN`s control of stress-induced corticosterone, oxytocin and prolactin secretion. Rats Were microinjected with saline or different doses (0.5, 5 and 50 pmol) of GABA-A (bicuculine) or GABA-B (phaclofen) antagonists in the PVN. Ten minutes later, they were subjected to a stressor (ether inhalation) and blood samples were collected 30 min before and 10, 30, 60, 90 and 120 min after the stressful stimulus to measure hormone levels by radioimmunoassay. Our results indicate that GABA acts in the PVN to inhibit stress-induced corticosterone secretion via both its receptor subtypes, especially GABA-B. In contrast, GABA in the PVN stimulates oxytocin secretion through GABA-B receptors and does not alter prolactin secretion. (C) 2008 Elsevier Inc. All rights reserved.

Antioxidant status and biomarkers of oxidative stress in bovine leukemia virus-infected dairy cows

Bovine leukemia virus (BLV) is among the most widespread livestock pathogens in many countries. Despite advances in understanding the pathogenesis of this disease, little is known about the involvement of oxidative stress. Therefore, this study examined the antioxidant status and the markers of oxidative stress in BLV-infected dairy cows. BLV infection was associated with an increase in triacylglycerol levels, a decrease in glutathione peroxidase (GSH-Px) activity and a tendency toward lower superoxide dismutase activity in the infected animals. No significant difference was observed in other markers of oxidative stress (i.e., conjugated dienes, hydroperoxides and malondialdehyde) in the infected animals compared to controls. A novel method for the analysis of oxidative stress, Z-scan based on the measurement of the mean-value of 9 in low density lipoprotein indicated that the infected animals had low-density lipoprotein particles that were slightly less modified than those from the healthy group. Thus, we conclude that BLV infection is associated with a selective decrease in GSH-Px activity without any alteration in the common plasma markers of oxidative stress. (C) 2011 Elsevier B.V. All rights reserved.

Finite-Element Analysis of Stress on Dental Implant Prosthesis

Background: Understanding how clinical variables affect stress distribution facilitates optimal prosthesis design and fabrication and may lead to a decrease in mechanical failures as well as improve implant longevity. Purpose: In this study, the many clinical variations present in implant-supported prosthesis were analyzed by 3-D finite element method. Materials and Method: A geometrical model representing the anterior segment of a human mandible treated with 5 implants supporting a framework was created to perform the tests. The variables introduced in the computer model were cantilever length, elastic modulus of cancellous bone, abutment length, implant length, and framework alloy (AgPd or CoCr). The computer was programmed with physical properties of the materials as derived from the literature, and a 100N vertical load was used to simulate the occlusal force. Images with the fringes of stress were obtained and the maximum stress at each site was plotted in graphs for comparison. Results: Stresses clustered at the elements closest to the loading point. Stress increase was found to be proportional to the increase in cantilever length and inversely proportional to the increase in the elastic modulus of cancellous bone. Increasing the abutment length resulted in a decrease of stress on implants and framework. Stress decrease could not be demonstrated with implants longer than 13 mm. A stiffer framework may allow better stress distribution. Conclusion: The relative physical properties of the many materials involved in an implant-supported prosthesis system affect the way stresses are distributed.

Effect of cantilever length and framework alloy on the stress distribution of mandibular-cantilevered implant-supported prostheses

The purpose of this in vitro study was to analyze the stress distribution on components of a mandibular-cantilevered implant-supported prosthesis with frameworks cast in cobalt-chromium (Co-Cr) or palladium-silver (Pd-Ag) alloys, according to the cantilever length. Frameworks were fabricated on (Co-Cr) and (Pd-Ag) alloys and screwed into standard abutments positioned on a master-cast containing five implant replicas. Two linear strain gauges were fixed on the mesial and distal aspects of each abutment to capture deformation. A vertical static load of 100 N was applied to the cantilever arm at the distances of 10, 15, and 20 mm from the center of the distal abutment and the absolute values of specific deformation were recorded. Different patterns of abutment deformation were observed according to the framework alloy. The Co-Cr alloy framework resulted in higher levels of abutment deformation than the silver-palladium alloy framework. Abutment deformation was higher with longer cantilever extensions. Physical properties of the alloys used for framework interfere with abutment deformations patterns. Excessively long cantilever extensions must be avoided. To cite this article:Jacques LB, Moura MS, Suedam V, Souza EAC, Rubo JH. Effect of cantilever length and framework alloy on the stress distribution of mandibular-cantilevered implant-supported prostheses.Clin. Oral Impl. Res. 20, 2009; 737-741.doi: 10.1111/j.1600-0501.2009.01712.x.

Solid-state Marx based two-switch voltage modulator for the On-Line Isotope Mass Separator accelerator at the European Organization for Nuclear Research

A new circuit topology is proposed to replace the actual pulse transformer and thyratron based resonant modulator that supplies the 60 kV target potential for the ion acceleration of the On-Line Isotope Mass Separator accelerator, the stability of which is critical for the mass resolution downstream separator, at the European Organization for Nuclear Research. The improved modulator uses two solid-state switches working together, each one based on the Marx generator concept, operating as series and parallel switches, reducing the stress on the series stacked semiconductors, and also as auxiliary pulse generator in order to fulfill the target requirements. Preliminary results of a 10 kV prototype, using 1200 V insulated gate bipolar transistors and capacitors in the solid-state Marx circuits, ten stages each, with an electrical equivalent circuit of the target, are presented, demonstrating both the improved voltage stability and pulse flexibility potential wanted for this new modulator.

Solid-State Bipolar Marx Converter with Output Transformer and Energy Recovery

The purpose of this paper is to present and discuss a general HV topology of the solid-state Marx modulator, for unipolar or bipolar generation connected with a step-up transformer to increase the output voltage applied to a resistive load. Due to the use of an output transformer, discussion about the reset of the transformer is made to guarantee zero average voltage applied to the primary. It is also discussed the transformer magnetizing energy recovering back to the energy storage capacitors. Simulation results for a circuit that generates 100 kV pulses using 1000 V semiconductors are presented and discussed regarding the voltage and current stress on the semiconductors and result obtained.

Effect of oxidative stress upon absorption of glucose by the human placenta: in vitro studies with BeWo cells

Pregnancy is a dynamic state and the placenta is a temporary organ that, among other important functions, plays a crucial role in the transport of nutrients and metabolites between the mother and the fetus, which is essential for a successful pregnancy. Among these nutrients, glucose is considered a primary source of energy and, therefore, fundamental to insure proper fetus development. Several studies have shown that glucose uptake is dependent on several morphological and biochemical placental conditions. Oxidative stress results from the unbalance between reactive oxygen species (ROS) and antioxidants, in favor of the first. During pregnancy, ROS, and therefore oxidative stress, increase, due to increased tissue oxygenation. Moreover, the relation between ROS and some pathological conditions during pregnancy has been well established. For these reasons, it becomes essential to understand if oxidative stress can compromise the uptake of glucose by the placenta. To make this study possible, a trophoblastic cell line, the BeWo cell line, was used. Experiments regarding glucose uptake, either under normal or oxidative stress conditions, were conducted using tert-butylhydroperoxide (tBOOH) as an oxidative stress inducer, and 3H-2-deoxy-D-glucose (3H-DG) as a glucose analogue. Afterwards, studies regarding the involvement of glucose facilitative transporters (GLUT) and the phosphatidylinositol 3-kinases (PI3K) and protein kinase C (PKC) pathways were conducted, also under normal and oxidative stress conditions. A few antioxidants, endogenous and from diet, were also tested in order to study their possible reversible effect of the oxidative effect of tBOOH upon apical 3H-DG uptake. Finally, transepithelial studies gave interesting insights regarding the apical-to-basolateral transport of 3H-DG. Results showed that 3H-DG uptake, in BeWo cells, is roughly 50% GLUT-mediated and that tBOOH (100 μM; 24h) decreases apical 3H-DG uptake in BeWo cells by about 33%, by reducing both GLUT- (by 28%) and non-GLUT-mediated (by 40%) 3H-DG uptake. Uptake of 3H-DG and the effect of tBOOH upon 3H-DG uptake are not dependent on PKC and PI3K. Moreover, the effect of tBOOH is not associated with a reduction in GLUT1 mRNA levels. Resveratrol, quercetin and epigallocatechin-3-gallate, at 50 μM, reversed, by at least 45%, the effect of tBOOH upon 3H-DG uptake. Transwell studies show that the apical-to-basolateral transepithelial transport of 3H-DG is increased by tBOOH.In conclusion, our results show that tBOOH caused a marked decrease in both GLUT and non-GLUT-mediated apical uptake of 3H-DG by BeWo cells. Given the association of increased oxidative stress levels with several important pregnancy pathologies, and the important role of glucose for fetal development, the results of this study appear very interesting.

Characterization of a polyubiquitin gene in T. thermophila and of ubiquitin gene expression during sexual reproduction and under stress conditions

A 5-unit polyubiquitin gene, TTU3, was isolated from a T. thermophila genomic library and sequenced. This gene presents an extra triplet coding for Phe, a AGAGA motif and a putative HSE element in its 5'-non-coding region. The ubiquitin gene expression in this ciliate was investigated by Northern blot hybridization in conjugating cells or cells under stress conditions. Exponentially growing cells express two ubiquitin mRNAs of 0.75 and 1.8 kb and a new species of 1.4 kb is induced under hyperthermic stress. During sexual reproduction of the cells (conjugation) the 1.8-kb mRNA is still transcribed whereas the steady-state population of the 0.75 mRNA transcripts is strongly diminished. Southern blot analysis suggests that ubiquitin in T. thermophila constitutes a large family of about ten members.

The influence of geometric factors on the wall shear stress distribution in realistic human coronary arteries

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Engenharia Biomédica. A presente dissertação foi desenvolvida no Erasmus Medical Center em Roterdão, Holanda

Oxidative stress in pregnancy and fertility pathologies

Oxidative stress designates the state of imbalance between reactive oxygen species (ROS) production and antioxidant levels. In a healthy placenta, there is an increase in ROS production, due to formation of new tissues and inherent metabolism, but this is balanced by higher levels of antioxidants. However, this balance is lost in some situations, with a consequent increase in oxidative stress levels. Oxidative stress has been implicated in several placental disorders and pregnancy pathologies. The present review intends to summarize what is known about the relationship between oxidative stress and well-known pregnancy disorders.