Alongamento estático, envelhecimento e desempenho neuromuscular

Pós-graduação em Ciências da Motricidade - IBRC

Respostas fisiológicas, bioquímicas e autonômicas de nadadores submetidos a dois modelos de treinamentos em nado atado com carga equiparada

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Toxicity of aged gasoline exhaust particles to normal and diseased airway epithelia

Particulate matter (PM) pollution is a leading cause of premature death, particularly in those with pre-existing lung disease. A causative link between particle properties and adverse health effects remains unestablished mainly due to complex and variable physico-chemical PM parameters. Controlled laboratory experiments are required. Generating atmospherically realistic Aerosols and performing cell-exposure studies at relevant particle-doses are challenging. Here we examine gasoline-exhaust particle toxicity from a Euro-5 passenger car in a uniquely realistic exposure scenario, combining a smog chamber simulating atmospheric ageing, an aerosol enrichment System varying particle number concentration independent of particle chemistry, and an aerosol Deposition chamber physiologically delivering particles on air-liquid interface (ALI) cultures reproducing normal and susceptible health status. Gasoline-exhaust is an important PM source with largely unknown health effects. We investigated acute responses of fully-differentiated normal, distressed (antibiotics treated) normal, and cystic fibrosis human bronchial epithelia (HBE), and a proliferating, single-cell type bronchial epithelial cell-line (BEAS-2B). We show that a single, short-term exposure to realistic doses of atmospherically-aged gasoline-exhaust particles impairs epithelial key-defence mechanisms, rendering it more vulnerable to subsequent hazards. We establish dose-response curves at realistic particle-concentration levels. Significant differences between cell models suggest the use of fully differentiated HBE is most appropriate in future toxicity studies.

Efficacy of progressive aquatic resistance training for tibiofemoral cartilage in postmenopausal women with mild knee osteoarthritis: a randomised controlled trial

OBJECTIVE: To study the efficacy of aquatic resistance training on biochemical composition of tibiofemoral cartilage in postmenopausal women with mild knee osteoarthritis (OA).

DESIGN: Eighty seven volunteer postmenopausal women, aged 60-68 years, with mild knee OA (Kellgren-Lawrence grades I/II and knee pain) were recruited and randomly assigned to an intervention (n = 43) and control (n = 44) group. The intervention group participated in 48 supervised aquatic resistance training sessions over 16 weeks while the control group maintained usual level of physical activity. The biochemical composition of the medial and lateral tibiofemoral cartilage was estimated using single-slice transverse relaxation time (T2) mapping and delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC index). Secondary outcomes were cardiorespiratory fitness, isometric knee extension and flexion force and knee injury and OA outcome (KOOS) questionnaire.

RESULTS: After 4-months aquatic training, there was a significant decrease in both T2 -1.2 ms (95% confidence interval (CI): -2.3 to -0.1, P = 0.021) and dGEMRIC index -23 ms (-43 to -3, P = 0.016) in the training group compared to controls in the full thickness posterior region of interest (ROI) of the medial femoral cartilage. Cardiorespiratory fitness significantly improved in the intervention group by 9.8% (P = 0.010).

CONCLUSIONS: Our results suggest that, in postmenopausal women with mild knee OA, the integrity of the collagen-interstitial water environment (T2) of the tibiofemoral cartilage may be responsive to low shear and compressive forces during aquatic resistance training. More research is required to understand the exact nature of acute responses in dGEMRIC index to this type of loading. Further, aquatic resistance training improves cardiorespiratory fitness.

Effect of consecutive repeated sprint and resistance exercise bouts on acute adaptive responses in human skeletal muscle

We examined acute molecular responses in skeletal muscle to repeated sprint and resistance exercise bouts. Six men [age, 24.7 ± 6.3 yr; body mass, 81.6 ± 7.3 kg; peak oxygen uptake, 47 ± 9.9 ml·kg -1 ·min -1; one repetition maximum (1-RM) leg extension 92.2 ± 12.5 kg; means ± SD] were randomly assigned to trials consisting of either resistance exercise (8 × 5 leg extension, 80% 1-RM) followed by repeated sprints (10 × 6 s, 0.75 N·m torque·kg -1) or vice-versa. Muscle biopsies from vastus lateralis were obtained at rest, 15 min after each exercise bout, and following 3-h recovery to determine early signaling and mRNA responses. There was divergent exercise order-dependent phosphorylation of p70 S6K (S6K). Specifically, initial resistance exercise increased S6K phosphorylation (?75% P < 0.05), but there was no effect when resistance exercise was undertaken after sprints. Exercise decreased IGF-I mRNA following 3-h recovery (?50%, P = 0.06) independent of order, while muscle RING finger mRNA was elevated with a moderate exercise order effect (P < 0.01). When resistance exercise was followed by repeated sprints PGC-1? mRNA was increased (REX1-SPR2; P = 0.02) with a modest distinction between exercise orders. Repeated sprints may promote acute interference on resistance exercise responses by attenuating translation initiation signaling and exacerbating ubiquitin ligase expression. Indeed, repeated sprints appear to generate the overriding acute exercise-induced response when undertaking concurrent repeated sprint and resistance exercise. Accordingly, we suggest that sprint-activities are isolated from resistance training and that adequate recovery time is considered within periodized training plans that incorporate these divergent exercise modes.

Antioxidant responses to an acute ultra-endurance exercise: Impact on DNA stability and indications for an increased need for nutritive antioxidants in the early recovery phase

Antioxidant requirements have neither been defined for endurance nor been defined for ultra-endurance athletes. To verify whether an acute bout of ultra-endurance exercise modifies the need for nutritive antioxidants, we aimed (1) to investigate the changes of endogenous and exogenous antioxidants in response to an Ironman triathlon; (2) to particularise the relevance of antioxidant responses to the indices of oxidatively damaged blood lipids, blood cell compounds and lymphocyte DNA and (3) to examine whether potential time-points of increased susceptibility to oxidative damage are associated with alterations in the antioxidant status. Blood that was collected from forty-two well-trained male athletes 2 d pre-race, immediately post-race, and 1, 5 and 19 d later was sampled. The key findings of the present study are as follows: (1) Immediately post-race, vitamin C, alpha-tocopherol, and levels of the Trolox equivalent antioxidant capacity, the ferric reducing ability of plasma and the oxygen radical absorbance capacity (ORAC) assays increased significantly. Exercise-induced changes in the plasma antioxidant capacity were associated with changes in uric acid, bilirubin and vitamin C. (2) Significant inverse correlations between ORAC levels and indices of oxidatively damaged DNA immediately and 1 d post-race suggest a protective role of the acute antioxidant responses in DNA stability. (3) Significant decreases in carotenoids and gamma-tocopherol 1 d post-race indicate that the antioxidant intake during the first 24 h of recovery following an acute ultra-endurance exercise requires specific attention. Furthermore, the present study illustrates the importance of a diversified and well-balanced diet to maintain a physiological antioxidant status in ultra-endurance athletes in reference to recommendations.

Acute and chronic effects of dietary nitrate supplementation on blood pressure and the physiological responses to moderate-intensity and incremental exercise

Dietary nitrate (NO3−) supplementation with beetroot juice (BR) over 4–6 days has been shown to reduce the O2 cost of submaximal exercise and to improve exercise tolerance. However, it is not known whether shorter (or longer) periods of supplementation have similar (or greater) effects. We therefore investigated the effects of acute and chronic NO3− supplementation on resting blood pressure (BP) and the physiological responses to moderate-intensity exercise and ramp incremental cycle exercise in eight healthy subjects. Following baseline tests, the subjects were assigned in a balanced crossover design to receive BR (0.5 l/day; 5.2 mmol of NO3−/day) and placebo (PL; 0.5 l/day low-calorie juice cordial) treatments. The exercise protocol (two moderate-intensity step tests followed by a ramp test) was repeated 2.5 h following first ingestion (0.5 liter) and after 5 and 15 days of BR and PL. Plasma nitrite concentration (baseline: 454 ± 81 nM) was significantly elevated (+39% at 2.5 h postingestion; +25% at 5 days; +46% at 15 days; P < 0.05) and systolic and diastolic BP (baseline: 127 ± 6 and 72 ± 5 mmHg, respectively) were reduced by ∼4% throughout the BR supplementation period (P < 0.05). Compared with PL, the steady-state V̇o2 during moderate exercise was reduced by ∼4% after 2.5 h and remained similarly reduced after 5 and 15 days of BR (P < 0.05). The ramp test peak power and the work rate at the gas exchange threshold (baseline: 322 ± 67 W and 89 ± 15 W, respectively) were elevated after 15 days of BR (331 ± 68 W and 105 ± 28 W; P < 0.05) but not PL (323 ± 68 W and 84 ± 18 W). These results indicate that dietary NO3− supplementation acutely reduces BP and the O2 cost of submaximal exercise and that these effects are maintained for at least 15 days if supplementation is continued.

Liver genomic responses to ciguatoxin: evidence for activation of Phase I and Phase II detoxification pathways following an acute hypothermic response in mice

Ciguatoxins (CTX) are polyether neurotoxins that target voltage-gated sodium channels and are responsible for ciguatera, the most common fish-borne food poisoning in humans. This study characterizes the global transcriptional response of mouse liver to a symptomatic dose (0.26 ng/g) of the highly potent Pacific ciguatoxin-1 (P-CTX-1). At 1 h post-exposure 2.4% of features on a 44K whole genome array were differentially expressed (p ≤ 0.0001), increasing to 5.2% at 4 h and decreasing to 1.4% by 24 h post-CTX exposure. Data were filtered (|fold change| ≥ 1.5 and p ≤ 0.0001 in at least one time point) and a trend set of 1550 genes were used for further analysis. Early gene expression was likely influenced prominently by an acute 4°C decline in core body temperature by 1 h, which resolved by 8 h following exposure. An initial downregulation of 32 different solute carriers, many involved in sodium transport, was observed. Differential gene expression in pathways involving eicosanoid biosynthesis and cholesterol homeostasis was also noted. Cytochrome P450s (Cyps) were of particular interest due to their role in xenobiotic metabolism. Twenty-seven genes, mostly members of Cyp2 and Cyp4 families, showed significant changes in expression. Many Cyps underwent an initial downregulation at 1 h but were quickly and strongly upregulated at 4 and 24 h post-exposure. In addition to Cyps, increases in several glutathione S-transferases were observed, an indication that both phase I and phase II metabolic reactions are involved in the hepatic response to CTX in mice.

Acute biochemical responses of a submersed macrophyte, Potamogeton crispus L., to high ammonium in an aquarium experiment

Acute biochemical responses of Potamogeton crispus L. to high external ammonium were investigated in an aquarium experiment. Shoots of P. crispus were incubated in aquaria for 24 h or 48 h at five treatments of ammonium-0, 1, 5, 10 and 20 mg/L NH4-N. Soluble sugar content of the shoots declined markedly with increasing ammonium levels, whereas soluble amino acid content increased dramatically. Responses of two antioxidant enzymes as well as soluble protein content fit a lognormal distribution with increasing ammonium levels. High ammonium levels (NH4-N greater than or equal to 5 mg/L) caused significant acute biochemical changes in P. crispus, which potentially could lead to significant biochemical damage.

Physiological and immune responses of zhikong scallop Chlamys farreri to the acute viral necrobiotic virus infection

The Zhikong Scallop, Chlamys farreri, is one of the most Important bivalve mollusks cultured in northern China However, mass mortality of the cultured C farreri has posed a serious threat to the maricultural Industry in recent years. Acute Viral Necrobiotic Virus (AVNV) is believed as an important etiological agent causing the scallop mass mortalities To understand the mechanism behind the AVNV associated scallop disease and mortality, we assessed the physiological and immune responses of C farreri to the virus infection using oxygen consumption rate, ammonium-nitrogen excretion rate, hemocyte copper, zinc superoxide dismutase gene expression, and plasma superoxide dismutase activity and alkaline phosphatase activity as indicators Scallops challenged by AVNV at 25 C developed typical disease signs 2 days after virus injection Before the disease manifested, scallop oxygen consumption and NH4+-N excretion rates rose and then fell back. Real-time PCR revealed that the hemocyte cytosol Cu, Zn SOD gene expression was upregulated followed by recovery The plasma SOD activity, however, augmented consistently following virus injection Moreover, plasma AKP activity first lowered and then elevated gradually to the highest level at 24 h post virus injection Scallops challenged by AVNV at 17 degrees C neither developed notable disease nor showed obvious responses that could be associated with the virus infection. While the results suggested a correlation between the elevated seawater temperature and the AVNV infection associated C farreri mortalities, they also indicated that the viral infection provoked multiple physiological and immune responses in the host scallops (C) 2010 Elsevier Ltd All rights reserved

Behavioral responses of tilapia (Oreochromis niloticus) to acute fluctuations in dissolved oxygen levels as monitored by computer vision

Behavioral and ventilatory parameters have the possibility of predicting the stress state of fish in vivo and in situ. This paper presents a new image-processing algorithm for quantifying the average swimming speed of a fish school in an aquarium. This method is based on the alteration in projected area caused by the movement of individual fish during frame sequences captured at given time intervals. The image enhancement method increases the contrast between fish and background, and is thus suitable for use in turbid aquaculture water. Behavioral parameters (swimming activity and distribution parameters) and changes in ventilation frequency (VF) of tilapia (Oreochromis niloticus) responded to acute fluctuations in dissolved oxygen (DO) which were monitored continuously in the course of normoxia, falling DO level, maintenance of hypoxia (three levels of 1.5, 0.8 and 0.3 mg l(-1)) and subsequent recovery to normoxia. These parameters responded sensitively to acute variations in DO level; they displayed significant changes (P < 0.05) during severe hypoxia (0.8 and 0.3 mg l(-1) level) compared with normoxic condition, but there was no significant difference under conditions of mild hypoxia (1.5 mg l(-1) level). There was no significant difference in VF between two levels of severe hypoxia 0.8 and 0.3 mg l(-1) level during the low DO condition. The activity and distribution parameters displayed distinguishable differences between the 0.8 and 0.3 mg l(-1) levels. The behavioral parameters are thus capable of distinguishing between different degrees of severe hypoxia, though there were relatively large fluctuations. (c) 2006 Elsevier B.V. All rights reserved.

The lack of associations between alleles at the hypoxia-Inducible factor 1A C1772T loci and responses to acute hypoxia.

Objective The aim of this study was to investigate the associations between alleles of the hypoxia-inducible factor 1A (HIF1A) C1772T polymorphism and several physiological responses to hypoxia, including the hypoxic ventilatory response (HVR), and serum erythropoietin (EPO), arterial oxygen saturation (Sao2), and acute mountain sickness (AMS) responses during 8 hours of exposure to normobaric hypoxia. Methods A total of 76 males participated in the study; 52 participants completed an 8-hour exposure to 12.7% oxygen, during which time Sao2, EPO concentrations, and AMS scores were measured, while 62 individuals took part in an HVR trial (in total 38 individuals completed both protocols). DNA was obtained from leukocytes, and a 346-bp fragment of the HIF1A gene containing the C1772T polymorphism was amplified using polymerase chain reaction. Fragments were sequenced to reveal individual genotypes, and the associations between HIF1A genotype and EPO, Sao2, AMS responses to hypoxia and HVR were examined. Results The magnitude of the hypoxic responses was highly variable between individuals. The increase in participants' EPO responses ranged from 89% to 388% of baseline values following hypoxia, while Sao2 values during the exposure ranged from 71% to 89%. The HVR ranged from −0.04 to +2.18 L · min−1 · Sao2%−1 among participants. No significant differences in EPO, Sao2, AMS, or HVR results were observed between the HIF1A CC genotype and the combined CT/TT genotype group. Conclusion In this study, the HIF1A C1772T polymorphism does not appear to influence EPO, Sao2, or AMS responses during acute hypoxic exposure, or the magnitude of the HVR.

Influence of acute vitamin C and/or carbohydrate ingestion on hormonal, cytokine, and immune responses to prolonged exercise

Davison, G. and Gleeson, M. (2005). Influence of Acute Vitamin C and/or Carbohydrate Ingestion on Hormonal, Cytokine, and Immune Responses to Prolonged Exercise. International Journal of Sport Nutrition and Exercise Metabolism. 15(5), pp.465-479 RAE2008

Kinetics of anti-Campylobacter jejuni monomeric and polymeric immunoglobulin A1 and A2 responses in serum during acute enteritis.

The intensity and kinetics of the serum polymeric and monomeric immunoglobulin A1 (IgA1) and IgA2 antibody responses to Campylobacter jejuni were analyzed. A rapid and marked serum IgA antibody response involving both the monomeric and polymeric components of IgA was observed after C. jejuni infections. IgA antibodies reached a peak of activity in serum during week 2 after the first symptoms of enteritis, about 10 days before the peak of IgG activity. Polymeric IgA accounted for most of the anti-C. jejuni activity at the peak of the IgA response (median, 90%; range, 44 to 98%) but rapidly disappeared from serum over a few weeks. In contrast, the serum monomeric IgA antibody response was low and was maintained over a prolonged period of time. Anti-C. jejuni IgA detected in the serum of healthy blood donors was mainly monomeric (median, 83%; range, 17 to 94%). In both the patients and the positive controls, IgA1 was the predominant (greater than 85%) subclass involved, even when the IgA antibody response was mainly polymeric. Our results suggest that polymeric IgA antibody responses are linked to a strong or persisting antigenic stimulation or both. Polymeric IgA antibodies appear to be a potential marker of acute C. jejuni infections, and their determination could provide a useful tool for the serological diagnosis of recent C. jejuni infections.