Metabolic and lactate responses to supramaximal exercise in elite junior soccer players and distance runners

Aim: Elite soccer players are considered not as excellent but as good endurance athletes. Because of the characteristics of the game which is faster and is played at higher intensity, a high anaerobic power is also required characteristic of elite soccer players. Hence, the purpose of the present study was to compare the metabolic and lactate responses to 30s maximal cycle ergometer tests in high school soccer players and distance runners. Methods: Ten elite high school male soccer players (SP) and ten elite high school male distance runners (DR) volunteered as subjects in this study. Anaerobic power measures were obtained using Wingate anaerobic test including peak power (PP) and mean power (MP). The oxygen uptake (VO_2) was recorded breath-by-breath during the test (30s) and during the first 30s of recovery. Blood samples for lactate concentrations were drawn at rest before the test and during the 30-min recovery period. Results: Values (±SEM) of PP were 647 (±27) and 568 (±24) W in the SP and DR, respectively being significant (P<0.05). During the test, the DR had a significantly greater VO_2 than the SP (P<0.01). Blood lactate concentrations, on the other hand in recovery after the test were higher in the SP than DR. Conclusion: Those results would indicate that the energy supply for the 30s supramaximal exercise depended on the competitive specialty. The energy supply of the SP was more provided by the anaerobic metabolism and in the DR by the aerobic system

Dysbindin-1, a Schizophrenia-Related Protein, Functionally Interacts with the DNA- Dependent Protein Kinase Complex in an Isoform-Dependent Manner

DTNBP1 has been recognized as a schizophrenia susceptible gene, and its protein product, dysbindin-1, is down-regulated in the brains of schizophrenic patients. However, little is known about the physiological role of dysbindin-1 in the central nervous system. We hypothesized that disruption of dysbindin-1 with unidentified proteins could contribute to pathogenesis and the symptoms of schizophrenia. GST pull-down from human neuroblastoma lysates showed an association of dysbindin-1 with the DNA-dependent protein kinase (DNA-PK) complex. The DNA-PK complex interacts only with splice isoforms A and B, but not with C. We found that isoforms A and B localized in nucleus, where the kinase complex exist, whereas the isoform C was found exclusively in cytosol. Furthermore, results of phosphorylation assay suggest that the DNA-PK complex phosphorylated dysbindin-1 isoforms A and B in cells. These observations suggest that DNA-PK regulates the dysbindin-1 isoforms A and B by phosphorylation in nucleus. Isoform C does not contain exons from 1 to 6. Since schizophrenia-related single nucleotide polymorphisms (SNPs) occur in these introns between exon 1 and exon 6, we suggest that these SNPs might affect splicing of DTNBP1, which leads to impairment of the functional interaction between dysbindin-1 and DNA-PK in schizophrenic patients

Isorhamnetin Promotes 53BP1 Recruitment through the Enhancement of ATM Phosphorylation and Protects Mice from Radiation Gastrointestinal Syndrome

Flavonoids are a subclass of polyphenols which are attractive, due to possessing various physiological activities, including a radioprotective effect. Tumor suppressor p53 is a primary regulator in the radiation response and is involved in the pathogenesis of radiation injuries. In this study, we revealed that isorhamnetin inhibited radiation cell death, and investigated its action mechanism focusing on DNA damage response. Although isorhamnetin moderated p53 activity, it promoted phosphorylation of ataxia telangiectasia mutated (ATM) and enhanced 53BP1 recruitment in irradiated cells. The radioprotective effect of isorhamnetin was not observed in the presence of ATM inhibitor, indicating that its protective effect was dependent on ATM. Furthermore, isorhamnetin-treated mice survived gastrointestinal death caused by a lethal dose of abdominal irradiation. These findings suggested that isorhamnetin enhances the ATM-dependent DNA repair process, which is presumably associated with the suppressive effect against GI syndrome

Thermal stress during table tennis bouts under high ambient temperature with and without fluid replacement

近年, 卓球は健康づくりや生涯スポーツの両面から実践者が増加している。高温多湿な本邦の夏季における長時間の卓球運動時の身体に対する暑熱ストレスはかなり大きいものと思われる。他方, 各種スポーツにおけるスポーツ飲料の活用は目覚しい。そこで本研究では高温多湿の環境下における長時間卓球練習時の生体に加わる暑熱ストレス軽減に対する水分補給効果について検討を試みた。The present study compared thermoregulatory and cardiovascular stresses during prolonged, simulated intermittent table tennis bouts (8×10-min bouts with 3-min rest intervals) at high ambient temperatures (30℃, 70%RH) with (F_I) and without (F_0). Four college table tennis players played against a table tennis robot that delivered 60 balls per min in the 2 environmental conditions. The performance task was to return the ball to a specific table target area on the table. During rest periods during F_I the subjects drank a commercial sport drink ad libitum. Pre- and post-trial measurements of body weight demonstrated a similar loss of sweat during F_0 and F_I after correcting the latter for fluid replacement. Rectal temperature (T_) arrd heart rate (HR) were significantly higher (P) followed similar patterns and no differences were observed between F_0 and F_I. This might be associated with similar rate of sweating during table tennis bouts in both trials. The intake of the carbohydrate-electrolyte fluid during F_I did not significantly affect plasma lactate. Thus the fluid intake during prolonged intermittent table tennis bouts was effective in reducing heat stress on thermoregulatory and cardiovascular functions

The effects of habitual cigarette smoking on maximal work capacity and pulmonary function

To evaluate the effects of cigarette smoking on some of the cardiorespiratory responses to maximal work as well as on pulmonary functions, a group of male adult subjects, 5 smokers and 5 nonsmokers, was studied. Work consisted of a bicycle ergometer test. For the determination of lung functions, Forced Vital Capacity (FVC) and Forced Expiratory Volume in one second (FEV_) were tested. FEV_%, the ratio of FEV_ to FVC was also calculated. A resting carboxyhemoglobin (HbCO) level in the smoking group was significantly (P and FE V_% in nonsmokers than those in smokers were significant. These findings suggest that habitual cigarette smoking lowers maximal work performance as well as pulmonary function

Blood lactate and ventilatory responses to interval-and endurance-training in recreational runners

The purpose of the present study was to compare threshold levels of blood lactate and ventilation after two different training programs of 9 weeks, that is, interval-run (IR) and endurance-run (ER). Twenty (20) recreational male runners from local running clubs volunteered to this study and completed maximal ramp cycle tests to determine maximal aerobic power (VO_2max) and blood lactate concentrations. Maximal cycle testing involved progressing in increments of 25 watts (W) every 2 minutes following a 4-min warm-up period at 0 W. The subjects were requested to maintain a pedaling frequency of 60 rpm. The test was continued till the subjects reached a point of exhaustion. After baseline tests, subjects were matched in terms of the VO_2max and placed in one of two training groups, an interval-run group (IR, mean age 40 years), and an endurance-run group (ER, mean age 41.7 years). Gas analysis was carried out every 20 sec for minute ventilation, oxygen consumption, carbon dioxide production using Metamax system. Calculation of ventilatory threshold (VT) employed the V-slope method. Blood samples were collected during exercise from the brachial vein for analyses of blood lactate using YSI 1500 Sport Lactate analyzer. The value of blood lactate concentrations corresponding to 4 mmol/L for determining the lactate threshold (LT) was chosen. After training, there were significant increases in VO_2max, the estimated LT-4 mmol/L, and VT in both groups. In addition, faster running performance of 10 km after a 9-week training program was observed in the IR and ER groups with no significant differences between the groups. However, the magnitude of the aforementioned improvements was greater in the IR than ER groups. Blood lactate concentrations in both groups lowered significantly at all given work rates after 100 W during the incremental graded exercise. However, the lactate concentrations at higher work rates were significantly lower in the IR than ER groups. It was concluded that both aerobic interval-training and endurance-training produce increases in performance and physiological parameters. However, it seemed that, for runners who are already trained, notable improvements in endurance performance can be achieved only through high-intensity interval training

A Novel RNA Synthesis Inhibitor, STK160830, Has Negligible DNA-Intercalating Activity for Triggering A p53 Response, and Can Inhibit p53-Dependent Apoptosis

RNA synthesis inhibitors and protein synthesis inhibitors are useful for investigating whether biological events with unknown mechanisms require transcription or translation; however, the dependence of RNA synthesis has been difficult to verify because many RNA synthesis inhibitors cause adverse events that trigger a p53 response. In this study, we screened a library containing 9600 core compounds and obtained STK160830 that shows anti-apoptotic effects in irradiated wild-type-p53-bearing human T-cell leukemia MOLT-4 cells and murine thymocytes. In many of the p53-impaired cells and p53-knockdown cells tested, STK160830 did not show a remarkable anti-apoptotic effect, suggesting that the anti-apoptotic activity is p53-dependent. In the expression analysis of p53, p53-target gene products, and reference proteins by immunoblotting, STK160830 down-regulated the expression of many of the proteins examined, and the downregulation correlated strongly with its inhibitory effect on cell death. mRNA expression analyses by qPCR and nascent RNA capture kit revealed that STK160830 showed a decreased mRNA expression, which was similar to that induced by the RNA synthesis inhibitor actinomycin D but differed to some extent. Furthermore, unlike other RNA synthesis inhibitors such as actinomycin D, p53 accumulation by STK160830 alone was negligible, and a DNA melting-curve analysis showed very weak DNA-intercalating activity, indicating that STK160830 is a useful inhibitor for RNA synthesis without triggering p53-mediated damage responses

Plasma β-endorphin and lactate to marathon running in male fun runners : a positive aspect responding to endurance exercise

The concentration of beta-endorphin (B-EP) was measured in 12 male recreational runners before and after marathon running. All subjects could finish 42 km distance and their mean time for finishing was 3 hr and 50 min (3 hr 6 min - 4 hr 22 min). Plasma B-EP significantly (P<0.0001) increased to about 9.8-fold above base line, from 9.1 ± 0.8 (SE) to 88.9±17.0 pg/ml. In addition, B-EP remained above baseline at 30 min and 60 min after the marathon race (43.9 + 12.7 pg/ml; P<0.0001 and 33.6± 6.6 pg/ml; P<0.001, respectively) and dropped to baseline 24 hr following the race. Lactate concentration also significantly (P<0.0001) increased during the marathon race (from 11.8±0.12 to 2.33± 0.18 mmol/L). This value was far below anaerobic threshold levels, 4 mmol/L, and was equivalent to approximately 60-65% VO_2max of our subjects. Previous studies have reported that the peripheral B-EP responses may be intensity dependent and that an exercise intensity of at least 70% VO_2max for 15 min is needed to increase plasma B-EP. Since our subjects performed extremely over-duration exercise and were exhausted after the race, therefore, the undue physical stress might affect the increase in B-EP. In conclusion, plasma B-EP responses may be both intensity and duration dependent