AGE-RELATED TRAJECTORY AND AGE AT PEAK COMPETITIVE PERFORMANCE IN WHEELCHAIR RUGBY PLAYERS AT THE PARALYMPIC GAMES.

OBJECTIVE: The first objective to examine the age-related trajectory of competitive performance and the age at peak competitive performance in wheelchair rugby (WR) players at the Paralympic Games. Another objective is to verify age correlations with performance over the years for each class. DESIGN: Retrospective cohort study. RESULTS: Data were collected from the official results books of the Paralympic games. The mean age (standard deviation) of the 267 players and 448 analyzed data from all Paralympic games (from Sidney 2004 to Tokyo 2020) across all classes was 32.8 (6.4) years, and the age at peak competitive performance was 30.6 (7.4) years. Each class had no statistical difference in age at peak competitive performance. Additionally, there was no significant correlation between age and performance within classes or across all Paralympic games. CONCLUSION: The findings indicate that WR players' age at peak competitive performance is 30.6 years, which remains consistent across all classes. There is no statistical correlation between age and performance in WR. These findings significantly affect effective talent identification and athlete development programs. This impact ensures that athletes receive the necessary support to reach their maximum potential while avoiding the pitfalls of underestimating or overestimating their stages of development.

Higher Physical Activity Level Improves Leptin Concentrations in Spinal Cord Injury Subjects.

The present study was designed to compare the body composition and indicators of chronic inflammatory grade, such as leptin, adiponectin, and resistin concentrations in irregularly active and active SCI subjects. Thirty-two male subjects participated in this study. They were divided into three groups: able-bodied control irregularly active (control, n = 11), irregularly active with SCI (SCI-IA, n = 8), and physically active with SCI (SCI-PA, n = 13). The enzyme-linked immunosorbent assay (ELISA) assessed serum concentrations of leptin, adiponectin, and resistin. All volunteers performed the maximum oxygen uptake (VO2max) test, 24 h total energy expenditure (TEE), and body composition by skinfold thicknesses. Leptin concentrations were higher in the SCI-IA group when compared to the other groups, while no significant differences were found between the SCI-PA and control cohorts. In addition, no significant differences were found among groups for serum adiponectin and resistin concentrations either. The SCI-PA group showed significantly higher values for TEE and VO2max when compared to the other groups. Percentages of body fat and circumference were decreased in the control and SCI-PA groups when compared to the SCI-IA cohort. Associations between leptin and cardiorespiratory capacity and anthropometric markers were also observed. Our findings highlight that the lack of physical activity in the SCI subjects leads to poor general physical fitness and higher levels of body adiposity, which may induce hyperleptinemia, an essential marker for cardiometabolic disorders.

Perfil da força muscular isométrica em atletas de rugby em cadeira de rodas / Profile of isometric muscle strength in athletes of wheelchair rugby

Objetivo: Analisar os níveis de força muscular em atletas de rugby em cadeira de rodas (RCR). Método: A amostra foi composta por 10 atletas (homens) com lesão da medula espinhal em nível cervical (tetraplegia) com média de idade de 31,1±5,06 anos. Os atletas foram recrutados na equipe de RCR do Projeto de Atividade Motora e Esporte Adaptado da Universidade Estadual de Campinas (ADEACAMP/UNICAMP). Resultados: Para analisar os níveis de força muscular isométrica (flexão e extensão dos ombros e cotovelos) foi utilizado dinamômetro isométrico, enquanto ultrassom foi usado para avaliação da espessura muscular (flexores e extensores do cotovelo, ambos os lados), utilizando 7,3 MHz da sonda linear-matriz. Correlação ponto-bisserial foi utilizada para verificar a associação entre os níveis de força de acordo com a posição de jogo; enquanto a correlação de Spearman verificou a associação entre os níveis de força entre membros dominantes e não dominantes, além da relação músculo agonista versus antagonista. Ainda, o teste Mann Whitney U foi utilizado para comparar os jogadores titulares e reservas quanto à força e espessura muscular. Conclusão: Podemos concluir que quanto maior a classificação funcional, maiores são os valores de força voluntária isométrica máxima; e que a força isométrica tem correlação com o desempenho de atletas de RCR

Objective: The aim of this study was to analyze muscle strength levels in wheelchair rugby athletes. Methods: The sample was 10 athletes (men) with spinal cord injury at cervical level (tetraplegia) with mean age of 31.1 ± 5.06 years. The athletes were recruited in the rugby team in wheelchair of the Motor Activity and Adapted Sport Project of the University of Campinas (ADEACAMP/UNICAMP). Results: In order to analyze the isometric muscular strength levels (flexion/extension of the shoulders and elbows), dynamometer was used, while muscle thickness was verified by ultrasound (flexors and extensors of the elbow, both sides), using 7.3 MHz of the linear-array probe. Point bi-serial correlation was applied to verify associations of game position and strength; while Spearman's correlation verified associations of strength and dominant and nondominant sides, and the relationship of agonist versus antagonist muscles. Moreover, the Mann Whitney U test was used to compare first to second-string players regarding strength and muscle thickness. Conclusion: We concluded that the higher the functional classification, higher the values of maximum isometric voluntary strength; and that the isometric strength correlates with their rugby performances

Muscle Strength Cutoff Points for Functional Independence and Wheelchair Ability in Men With Spinal Cord Injury.

OBJECTIVE: Determine trunk and shoulder muscle strength cutoff points for functional independence and wheelchair skills, and verify the predictive capacity of relative and absolute peak torque in men with spinal cord injury (SCI). DESIGN: Cross-sectional study. SETTING: Rehabilitation hospital setting. PARTICIPANTS: Men (N=54) with SCI were recruited and stratified into high and low paraplegia groups. INTERVENTIONS: All participants performed maximum strength tests for shoulder abduction or adduction (isokinetic) and trunk flexion or extension (isometric) to determine relative and absolute peak torque cutoff points for the Spinal Cord Independence Measure version III (SCIM-III) and Adapted Manual Wheelchair Circuit (AMWC). MAIN OUTCOME MEASURES: The primary outcome measures were SCIM-III, AMWC-Brazil test, and strength variables (peak torques). Demographic characteristics obtained from participants' electronic medical records were the secondary outcomes used as predictor variables of functional independence. RESULTS: The best predictive model for SCIM-III (R=0.78, P≤.05) used the sum of trunk flexion and extension relative peak torque values to determine the cutoff points (1.42 N·m/kg for a score of 70). Relative shoulder abduction peak torque was used in the predictive models for AMWC outcomes: performance score (R=0.77, P≤.05, cutoff points of 0.97 N·m/kg for 300.0m) and 3-minute overground wheeling (R=0.72, P≤.05, cutoff points of 0.96 N·m/kg for 18.5s). CONCLUSIONS: Relative peak torque showed better predictive capacity compared to absolute peak torque. Cutoff points were established for relative muscle strength and could help health professionals set appropriate goals for individuals with SCI to achieve high functional independence and wheelchair ability.

Differences of Relative and Absolute Strength of Individuals With Spinal Cord Injury From Able-Bodied Subjects: A Discriminant Analysis.

CONTEXT: Strength training is one of the most common interventions employed to increase functional independence during rehabilitation of individuals with spinal cord injury (SCI). However, in the literature, different results have been reported in terms of strength modifications after a SCI compared with a control group (CG). OBJECTIVE: This study aimed to verify whether discriminant analysis using relative and absolute strength is able to discriminate individuals with different levels of SCI from a CG and to compare strength values of men with different levels of SCI with a CG. DESIGN: Cross-sectional study. SETTING: Rehabilitation hospital setting. PARTICIPANTS: A total of 36 individuals with SCI stratified in tetraplegia (TP; C6-C8), high paraplegia (HP; T1-T6), and low paraplegia (LP; T7-L2), and 12 matched control subjects were enrolled in the study. MAIN OUTCOME MEASURES: The subjects performed a maximum strength test of elbow extension/flexion and also shoulder abduction/adduction and flexion/extension in an isokinetic dynamometer. Discriminant analysis was carried out to identify which strength variables would be able to discriminate the TP, HP, or LP groups from the CG. A 1-way analysis of variance was performed to compare peak torque and agonist/antagonist ratio means. RESULTS: Shoulder adduction, followed by elbow extension peak torque, was the best variable for discriminating the TP group from the CG (function coefficients: -0.056 and 0.051, respectively, Wilks Λ = 0.41, P ≤ .05). There were no significant differences between the HP group, LP group, and CG. CONCLUSIONS: The strength similarity of the paraplegic groups and the CG should not be extrapolated for activities of daily living or sports. The TP group demonstrated lower peak torque for all movements than the CG.

Fish Oil Supplementation Enhances Pulmonary Strength and Endurance in Women Undergoing Chemotherapy.

We investigated the effect of fish oil (FO) supplementation, at 4 g/day, on the respiratory performance and blood lipid profile of 32 patients with breast cancer at the beginning of chemotherapy. They were randomized into two groups: control (C) and FO supplemented (S). Both groups underwent three respiratory evaluations and blood harvest (before chemotherapy-Day 0, and 30 and 60 days after supplementation). The S group showed a significant increase in the maximal inspiratory and expiratory pressure (P ≤ 0.05 vs. Day 0) and in the maximum voluntary ventilation (P ≤ 0.05). In the treadmill 6-min-walk test, the S group had a significant increase in the walked distance (P ≤ 0.05). Blood lactate concentration was significantly lower in the S group after 60 days, at rest, when compared to C (P ≤ 0.05). Plasma high-density lipoprotein (HDL) cholesterol concentration remained the same after 60 days of supplementation, while in the C group, it decreased significantly (P ≤ 0.05 Day 0 vs. Day 60). Triacylglycerol (TAG) plasma concentration in the S group was lower when compared to the C group (P ≤ 0.05 Day 60S vs. Day 60). Supplementation with FO caused improvement in the respiratory muscle strength and endurance, ameliorated functional performance, and kept TAG, HDL cholesterol, and lactate plasma concentration at normal levels.

Impact of Wheelchair Rugby on Body Composition of Subjects With Tetraplegia: A Pilot Study.

OBJECTIVE: To investigate the longitudinal effects of wheelchair rugby (WR) training on body composition of subjects with tetraplegia. DESIGN: Subjects were evaluated at baseline and after WR training. SETTING: Faculty of physical education settings. PARTICIPANTS: Individuals with tetraplegia (N=13; age, 26.6±6.0y). INTERVENTIONS: Four sessions per week of WR training composed by aerobic and anaerobic activities and technical and tactical aspects of WR. The average time of intervention was 8.1±2.5 months. MAIN OUTCOME MEASURES: Body composition assessed by dual-energy x-ray absorptiometry. RESULTS: After training, fat mass was significantly reduced in the whole body (15,191±4603 vs 13,212±3318 g, P=.016), trunk (7058±2639 vs 5693±1498 g, P=.012), and legs (2847±817 vs 2534±742 g, P=.003). Conversely, increased bone mineral content (183±35 vs 195±32 g, P=.01) and fat-free mass (2991±549 vs 3332±602 g, P=.016) in the arms and reduced bone mineral content in the trunk (553±82 vs 521±86 g, P=.034) were observed after training. Furthermore, no significant correlation between the duration of training and changes in body composition was detected. CONCLUSIONS: Regular WR training increased lean mass and bone mineral content in the arms and decreased total body fat mass. Conversely, WR training was associated with decreased bone mineral content in the trunk. These results suggest that regular WR training improves body composition in subjects with tetraplegia.

Avaliação isocinética em atletas da seleção brasileira de futebol de 5 / Isokinetic evaluation of Brazilian 5-a-side team / Evaluación isocinética en los atletas de la selección Brasileña de fútbol de 5

INTRODUÇÃO: A força muscular (FM) dos membros inferiores é um dos principais componentes exigidos para as ações específicas durante a prática do futebol de 5 e, quando apresentam níveis insuficientes, desequilíbrios bilaterais elevados ou acentuada diferença na razão agonista/antagonista (RAA) são fatores que contribuem para o desenvolvimento de lesões musculoesqueléticas. OBJETIVO: A proposta deste estudo foi avaliar os níveis de torque máximo, a diferença bilateral na produção de força e a razão convencional das musculaturas flexoras e extensoras do joelho em diferentes velocidades de execução. MÉTODOS: Participaram do estudo 11 atletas deficientes visuais. Os atletas foram submetidos à avaliação antropométrica para determinação da composição corporal e submetidos à avaliação com dinamômetro isocinético para a mensuração dos níveis de desequilíbrio muscular e razão convencional. RESULTADOS: Nos movimentos concêntricos da musculatura flexora foram observadas diferenças significativas no pico de torque (PT) entre os membros dominante (MD) e não dominante (MND) na velocidade de 60°.s-1 e 180°.s-1, no pico de torque normalizado (PTN) a 60°.s-1 e na velocidade de 180°.s-1 para os músculos extensores. Na RAA, observou-se diferença significativa entre MD e MND, e níveis aceitáveis de RAA em ambas as pernas, de acordo com o proposto para o futebol convencional. CONCLUSÃO: Espera-se que os resultados do presente estudo possam contribuir para os processos de prevenção, treinamento e reabilitação de atleta de futebol de 5, como também, servirem como parâmetros para futuros estudos. .

INTRODUCTION: Muscle strength (MS) of the lower limbs is one of the main components required for specific actions during practice of 5-a-side football and when the levels are insufficient, elevated bilateral imbalances or marked difference in agonist/antagonist ratio (AAR) are factors that contribute to the development of musculoskeletal injuries. OBJECTIVE: The purpose of this study was to assess levels of peak torque, bilateral difference in force production and conventional ratio of flexor and extensor musculature of the knee in different speeds. METHODS: The study included 11 visually impaired athletes. The athletes underwent anthropometric measurements to determine body composition and underwent evaluation at the isokinetic dynamometer to measure the levels of muscle imbalance and conventional ratio. RESULTS: In concentric movements of the flexor muscles, significant differences were observed in peak torque (PT) between the dominant limb (DL) and non-dominant limb (NDL) at 60° .s-1 and 180°.s-1, the peak torque standardized (PTS) at 60°.s-1 and 180 °.s-1 to the extensor muscles. In AAR, there was significant difference between DL and NDL, and acceptable levels of AAR in both legs according to the proposed for conventional football. CONCLUSION: It is expected that the results of this study may contribute to the processes of prevention, training and rehabilitation in athletes of 5-a-side football, also, serve as parameters for future studies. .

INTRODUCCIÓN: La fuerza muscular (FM) de los miembros inferiores es uno de los principales componentes necesarios para acciones específicas durante la práctica de fútbol de 5 y, cuando presentan niveles insuficientes, los desequilibrios bilaterales elevados o acentuada diferencia en la razón agonista/antagonista (RAA), son factores que contribuyen para el desarrollo de lesiones musculoesqueléticas. OBJETIVO: En este sentido, la propuesta del estudio fue evaluar los niveles de torque máximo, diferencia bilateral en la producción de fuerza y razón convencional de las musculaturas flexoras y extensoras de la rodilla en diferentes velocidades de ejecución. MÉTODOS: Participaron en el estudio 11 atletas con discapacidad visual. Los atletas fueron sometidos a evaluación antropométrica para determinación de la composición corporal y sometidos a evaluación en el dinamómetro isocinético para medir los niveles de desequilibrio muscular y la razón convencional. RESULTADOS: En los movimientos concéntricos de la musculatura flexora, se observaron diferencias significativas en el pico de torque (PT) entre los miembros dominantes (MD) y no dominante (MND) en la velocidad de 60°.s-1 y 180°.s-1, en el pico de torque normalizado (PTN) a 60°.s-1 y 180°.s-1 para los músculos extensores. En la RAA se observó diferencia significativa entre MD y MND, y niveles aceptables de RAA en ambas piernas de acuerdo con lo propuesto para el fútbol convencional. CONCLUSIÓN: Se espera que los resultados del presente estudio puedan contribuir para los procesos de prevención, entrenamiento y rehabilitación de los atletas de fútbol de 5, así como también que sirvan como parámetros para futuros estudios. .

Energy expenditure in individuals with spinal cord injury quantified by doubly labeled water and a multi-sensor armband.

BACKGROUND: The objective of this study was to determine whether doubly labeled water (DLW) and a multi-sensor armband (SWA) could detect the variation in energy expenditure incurred by a period of increased exercise (EXE) versus a period of high sedentary activity (SED), in individuals with spinal cord injury (SCI). METHODS: Eight participants with SCI were submitted to 2 testing periods of energy expenditure assessment: 1) a 14-day phase during which sedentary living conditions were imposed and 2) a 14-day phase during which an exercise training intervention was employed. For each phase, total daily energy expenditure (TDEE) and physical activity energy expenditure (PAEE) were measured by DLW and SWA. RESULTS: Mean TDEE assessed by DLW, was significantly higher during EXE versus SED (11,605 ± 2151 kJ·day⁻¹ and 10,069 ± 2310 kJ·day⁻¹). PAEE predicted by DLW was also significantly higher during EXE versus SED (5422 ± 2240 kJ·day⁻¹ and 3855 ± 2496 kJ·day⁻¹). SWA-predicted PAEE significantly underestimated PAEE measured by the DLW during SED and EXE. CONCLUSION: DLW is sensitive to detect variation in within-individual energy expenditure during voluntary increase in physical activity in individuals with SCI. SWA failed to detect statistically significant variations in energy expenditure between periods of high versus low activity in SCI.

Exercise, energy expenditure, and body composition in people with spinal cord injury.

BACKGROUND: The objective of this study was to verify the long-term effects of exercise on energy expenditure and body composition in individuals with spinal cord injury (SCI), as very little information is available on this population under free-living conditions. METHODS: Free-living energy expenditure and body composition using doubly labeled water (DLW) was measured in 13 individuals with SCI, subdivided in 2 groups: (1) sedentary (SED; N = 7) and (2) regularly engaged in any exercise program, for at least 150 min·wk(-1) (EXE; N = 6). RESULTS: The total daily energy expenditure (TDEE) was significantly higher in the EXE group (33 ± 4.5 kcal·kg(-1)·day(-1)) if compared with SED group (27 ± 4.3 kcal·kg(-1)·day(-1)). The percentage of body fat was significantly higher in SED group than in EXE group (38 ± 6% and 28 ± 9%). CONCLUSION: Our findings revealed that, despite the severity of SCI, the actual ACSM's guidelines for weight management for healthy adults exercise could significantly increase TDEE and BMR and improve body composition in individuals who regularly perform exercise. However, the EXE group still showed a high percentage of body fat, suggesting that a more specific approach might be considered (ie, increased intensity or volume, or combining with a diet program).

Exercise responses during functional electrical stimulation cycling in individuals with spinal cord injury.

PURPOSE: This study compared acute exercise responses during arm cranking, functional electrical stimulation (FES)-assisted leg cycling, and combined arm and leg ("hybrid") cycling in individuals with spinal cord injury during maximal and submaximal exercise. METHODS: Nine male subjects with long-standing neurological lesions from C7 to T12 were recruited. All subjects performed arm crank ergometry (ACE), FES leg cycle exercise (FES-LCE), combined ACE + FES-LCE, and cycling on a hybrid FES tricycle (HYBRID). They were assessed for their peak exercise responses in all four modalities. Subsequently, their submaximal heart rates (HR), cardiac outputs (Q), stroke volumes (SV), and arteriovenous oxygen extractions (Ca-Cv)O2 were measured at 40%, 60%, and 80% of mode-specific V˙O2peak. RESULTS: Arm exercise alone and arm + leg exercise resulted in significantly higher V˙O2peak and HRpeak compared with FES-LCE (P < 0.05). Submaximal V˙O2 during FES-LCE was significantly lower than all other modalities across the range of exercise intensities (P < 0.05). ACE elicited 70%-94% higher steady-state V˙O2, and HYBRID evoked 99%-148% higher V˙O2 compared with FES-LCE. Steady-state FES-LCE also produced significantly lower Q, HR, and (Ca-Cv)O2. ACE evoked 31%-36% higher Q and 19%-47% greater HR than did FES-LCE. HYBRID elicited 31%-49% greater Q and 23%-56% higher HR than FES-LCE. CONCLUSIONS: Combined arm and leg exercise can develop a higher oxygen uptake and greater cardiovascular demand compared with ACE or FES-LCE alone. These findings suggested that combined arm + leg FES training at submaximal exercise intensities may lead to greater gains of aerobic fitness than would arm exercise alone. These data also proffered that FES leg cycling exercise by itself may be insufficient to promote aerobic fitness in the spinal cord injury population.

Comparison of methods to assess energy expenditure and physical activity in people with spinal cord injury.

OBJECTIVE: To compare different methods of assessing energy expenditure (EE) and physical activity (PA) in people with spinal cord injury (SCI) under community-dwelling conditions. METHODS: A reference standard encompassing the doubly labelled water (DLW) technique, heart rate monitoring (FLEX-HR), a multi-sensor armband (SenseWear Armband (SWA)), and two PA recall questionnaires were employed in 14 people with SCI to estimate EE and leisure-time PA. RESULTS: Mean total daily energy expenditure (TDEE) assessed by DLW, FLEX-HR, and SWA were 9817 ± 2491 kJ/day, 8498 ± 1516 kJ/day, and 11414 ± 3242 kJ/day, respectively. Physical activity energy expenditure (PAEE) quantified by DLW was 2841 ± 1626 kJ/day, 2935 ± 1732 kJ/day estimated from FLEX-HR, and 2773 ± 2966 kJ/day derived from SWA. After converting the PA recall questionnaire data to EE in kJ/day, PAEE for the Physical Activity Recall Assessment for People with Spinal Cord Injury (PARA-SCI) was 2339 ± 1171 kJ/day and for Physical Activity Scale for Individuals with Physical Disabilities (PASIPD) 749 ± 1026 kJ/day. DLW-quantified PAEE was moderately associated with PARA-SCI (R(2) = 0.62, P < 0.05), but not with the other estimates of PAEE (R(2) ranged between 0.13 and 0.30, P > 0.05). CONCLUSION: Our findings revealed that the PARA-SCI recall questionnaire was the best estimate of PAEE compared to the reference standard DLW approach. Although the between-method variability for SWA, FLEX-HR, and PASIPD-derived PAEE was small, there was a weak association between these methods and the criterion DLW technique. The best estimate of DLW-quantified TDEE was by FLEX-HR. SWA significantly overestimated TDEE in this population.

Low fish oil intake improves insulin sensitivity, lipid profile and muscle metabolism on insulin resistant MSG-obese rats.

BACKGROUND: Obesity is commonly associated with diabetes, cardiovascular diseases and cancer. The purpose of this study was to determinate the effect of a lower dose of fish oil supplementation on insulin sensitivity, lipid profile, and muscle metabolism in obese rats. METHODS: Monosodium glutamate (MSG) (4 mg/g body weight) was injected in neonatal Wistar male rats. Three-month-old rats were divided in normal-weight control group (C), coconut fat-treated normal weight group (CO), fish oil-treated normal weight group (FO), obese control group (Ob), coconut fat-treated obese group (ObCO) and fish oil-treated obese group (ObFO). Obese insulin-resistant rats were supplemented with fish oil or coconut fat (1 g/kg/day) for 4 weeks. Insulin sensitivity, fasting blood biochemicals parameters, and skeletal muscle glucose metabolism were analyzed. RESULTS: Obese animals (Ob) presented higher Index Lee and 2.5 fold epididymal and retroperitoneal adipose tissue than C. Insulin sensitivity test (Kitt) showed that fish oil supplementation was able to maintain insulin sensitivity of obese rats (ObFO) similar to C. There were no changes in glucose and HDL-cholesterol levels amongst groups. Yet, ObFO revealed lower levels of total cholesterol (TC; 30%) and triacylglycerol (TG; 33%) compared to Ob. Finally, since exposed to insulin, ObFO skeletal muscle revealed an increase of 10% in lactate production, 38% in glycogen synthesis and 39% in oxidation of glucose compared to Ob. CONCLUSIONS: Low dose of fish oil supplementation (1 g/kg/day) was able to reduce TC and TG levels, in addition to improved systemic and muscle insulin sensitivity. These results lend credence to the benefits of n-3 fatty acids upon the deleterious effects of insulin resistance mechanisms.

Beta-hydroxy-beta-methylbutyrate supplementation reduces tumor growth and tumor cell proliferation ex vivo and prevents cachexia in Walker 256 tumor-bearing rats by modifying nuclear factor-kappaB expression.

Cancer cachexia syndrome contributes to wasting and weight loss leading to inefficacy of anticancer therapy. In this study, the anticatabolic agent beta-hydroxy-beta-methylbutyrate (HMB) was supplemented to adult Walker 256 tumor-bearing rats during 8 weeks aiming to determine if tumor burden could be reduced. Male Wistar rats were randomly assigned to nontumor and tumor-bearing groups and fed regular chow or regular chow plus HMB supplemented (76 mg/kg body weight). Beta-hydroxy-beta-methylbutyrate supplementation induced a lower tumor weight and tumor cell proliferation ex vivo, totally prevented glycemia reduction, as well as blunted the increase in the serum lactate concentrations and also preserved glycogen stores in tumor-bearing rats. Reduction in tumor cell proliferation ex vivo was accompanied by increased nuclear factor-kappaB inhibitor-alpha content by more than 100%. In contrast, nuclear factor-kappaB p65 subunit content was suppressed by 17% with HMB supplementation. In conclusion, HMB supplementation, at a similar dose used in humans to increase muscle mass, caused antitumor and anticachectic effects, with tumor-cell nuclear factor-kappaB pathway participation, which might be a potential nutritional strategy in cancer therapy.

Glutamine concentration and immune response of spinal cord-injured rats.

BACKGROUND/OBJECTIVES: Glutamine plays a key role in immune response. Spinal cord injury (SCI) leads to severe loss of muscle mass and to a high incidence of infections. This study investigated the acute effect of SCI (2 and 5 days) on the plasma glutamine and skeletal muscle concentrations and immune responses in rats. METHODS: A total of 29 adult male Wistar rats were divided as follows: control (C; n = 5), sham-operated (S2; n = 5) and spinal cord-transected (T2; n = 7). They were killed on day 2 after surgery/transection (acute phase). Another set was sham-operated (S5; n = 5), spinal cord-transected (T5; n = 7), and killed at day 5 after surgery/transection (secondary phase). Blood was collected; the white portion of the epitrochlearis and gastrocnemius muscles and the red portion of soleus muscles were dissected to measure the glutamine concentration. Gut-associated lymphocytes and peritoneal macrophages were obtained for immune parameters measurements. RESULTS: Glutamine concentration in the plasma, gastrocnemius, and soleus muscles in rats with SCI were significantly reduced but not in the epitrochlearis muscle in the acute (2 days) and secondary (5 days) phases. Phagocytic response was reduced in the acute phase but increased in the secondary phase in rats with SCI. Superoxide production, on the other hand, was significantly increased at days 2 and 5 after SCI, and CD8+ lymphocytes subset decreased significantly on days 2 and 5. CONCLUSIONS: Our results showed reduction in plasma glutamine and skeletal muscle concentrations after spinal cord transection. They also suggest that SCI and glutamine reduction contribute to an alteration in immune competence.

Decreased tumor growth in Walker 256 tumor-bearing rats chronically supplemented with fish oil involves COX-2 and PGE2 reduction associated with apoptosis and increased peroxidation.

Many studies have shown that addition of fish oil (FO) to the diet reduces tumor growth but the mechanism(s) of action involved is (are) still unknown. In this study, we examine some possible mechanisms in tumor-bearing rats chronically supplemented with FO. Male Wistar rats (21 days old) were fed with regular chow and supplemented with coconut or FO (1g/kg body weight) until they reached 70 days of age. Then, they were inoculated with a suspension of Walker 256 ascitic tumor cells (2 x 10(7)ml) and after 14 days they were killed. Supplementation with FO resulted in significantly lower tumor weight, greater tumor cell apoptosis, lower ex vivo tumor cell proliferation, a higher tumor content of lipid peroxides, lower expression of cyclooxygenase-2 (COX-2) in tumor tissue and a lower plasma concentration of prostaglandin E2 than observed in rats fed regular chow or supplemented with coconut oil. These results suggest that reduction of tumor growth by FO involves an increase in apoptosis and of lipid peroxidation in tumor tissue, with a reduction in tumor cell proliferation ex vivo, COX-2 expression and PGE2 production. Thus, FO may act simultaneously through multiple effects to reduce tumor growth. Whether these effects are connected through a single underlying mechanism remains to be seen.

The effects of peroxovanadate and peroxovanadyl on glucose metabolism in vivo and identification of signal transduction proteins involved in the mechanism of action in isolated soleus muscle.

The insulin-like effects of peroxovanate (POV) and peroxovanadyl (PSV) on rates of lactate formation and glycogen synthesis were measured in isolated incubated soleus muscle preparations. In another experiment rats were made insulin deficient by streptozotocin injection and treated with POV and PSV (0.25 mM) administered in the drinking water and in the course of 7 days glycemia were determined. Also, signal transduction proteins ERK 1 and ERK 2 involved in the insulin signaling were measured in soleus muscle of diabetic rats treated with POV and PSV. Peroxides of vanadate and vanadyl significantly stimulated glucose utilization in soleus muscle preparations in vitro. The stimulation of glycogen synthesis and lactate formation by POV and PSV was similar to insulin stimuli. Rats treated with POV or PSV presented reduction of glycemia, food and fluid intake with amelioration of the diabetic state during the short period of treatment (7 days). POV and PSV modulated ERK1/2 phosphorilation and the insulin administration in these rats caused an addictive effect on phosphorilation state of these proteins.