RELATIONSHIP BETWEEN PERFORMANCE AND VERTICAL STIFFNESS IN TRIATHLON RUNNING DURING A COMPETITION

The purpose of this study was to clarify the relationship between performance and vertical stiffness of triathletes in isolated running (IR; running without a prior swim and cycling) and triathlon running (TR; running preceded by a 1.5-km swim and 40-km cycling). The mean running speed during 10-km run and the vertical stiffness in IR and TR conditions were assessed. The vertical stiffness was positively related to the running speed in both, the IR and TR conditions. The relationship between the running speed and the vertical stiffness were stronger in TR than in IR. Improvement of vertical stiffness should be important to enhance the performance in TR

Nitrogen Fixation Mutants of the Actinobacterium Frankia Casuarinae CcI3

Frankia is a representative genus of nitrogen-fixing (N2-fixing) actinobacteria; however, the molecular mechanisms underlying various phenomena such as the differentiation of a N2 fixation-specific structure (vesicle) and the regulation of N2 fixation (nif) genes, have yet to be elucidated in detail. In the present study, we screened hyphal fragments of Frankia casuarinae that were mutagenized by 1-methyl-3-nitro-1-nitrosoguanidine or gamma rays, and isolated 49 candidate N2 fixation mutants. Twelve of these mutants were selected for further study, and their abilities to grow in NH3-deficient (N-) liquid media and their rates of acetylene reduction activities were evaluated. Eleven mutant strains were confirmed to lack the ability to fix N2. Five mutant strains formed significantly reduced numbers of vesicles, while some failed to form large mature vesicles. These vesicle mutants also exhibited an aberrant hyphal morphology, suggesting a relationship between vesicle differentiation and hyphal branching. Ten mutants showed significant reductions in the expression of nifE, nifH, and nifV genes under N- conditions. The genome sequencing of eight mutants identified 20 to 400 mutations. Although mutant strains N3H4 and N6F4 shared a large number of mutations (108), most were unique to each strain. Mutant strain N7C9 had 3 mutations in the nifD and nifH genes that may result in the inability to fix N2. The other mutant strains did not have any mutations in any known N2 fixation-related genes, indicating that they are novel N2 fixation mutants

THE EFFECTS OF A MARATHON RACE ON RUNNING ECONOMY AND LEG MUSCULAR STRENGTH AND POWER

INTRODUCTION: Previous studies have reported that running economy as well as leg muscular strength and power decrease after a marathon race(Nicol et al., 1991 ; Chevrolet et al. 1993). However, the relationship between the change in running economy and the change in muscular strength and power is still unclear. Therefore, the purpose of this study was to examine the effects of a marathon race on running economy, as well as leg muscular strength and power. Relationships among race performance, decrease in running economy and decrease in leg muscular strength and power were also investigated. METHODS: Thirteen healthy males performed treadmill running (200 m/min., 3 min.), isometric knee extension (3s), counter-movement-jump and 5-series-jumps 3-1 day(s) before (PRE) and immediately after (POST) participating in either the 1996 or 1997 "Tsukuba marathon race (42.195 km) ". RESULTS: 1) Mean race time of the marathon was 2 hours 57 minutes 39 seconds. Average running speed during the latter half of the race was significantly lower than the former half . 2) In comparison to PRE, oxygen consumption during treadmill running in POST increased significantly while maximal strength of isometric knee extension, jumping height of counter-movement-jump and jumping height of 5-series-jumps decreased significantly . 3) There were no relationships between percent change ((Post-Pre)/Pre x 100) in oxygen consumption during treadmill running and percent change in leg muscular strength and power. 4) There was a significant correlation between percent change ((Latter- Former)/Former x 100) in running speed during the race and percent change in jumping height of counter-movement-jump (r=0.541). However, no significant relationship was observed between percent change in running speed and percent change in running economy. CONCLUSION: Running a marathon race decreases both running economy and muscular strength and power but these seem to be caused by different mechanisms. The decrease in leg muscular strength and power during the marathon race seems have been an influence on the decrease in running speed during the latter half of the race. REFERENCES Chevrolet et al. (1993) Med. Sci. Sports Exerc. 25:501-507. Nicol et al. (1991) Scand. J. Sports Med. 1:195-204

Synaptic Structure and Function in the Mouse Somatosensory Cortex during Chronic Pain: In Vivo Two-Photon Imaging

Recent advances in two-photon microscopy and fluorescence labeling techniques have enabled us to directly see the structural and functional changes in neurons and glia, and even at synapses, in the brain of living animals. Long-term in vivo two-photon imaging studies have shown that some postsynaptic dendritic spines in the adult cortex are rapidly eliminated or newly generated, in response to altered sensory input or synaptic activity, resulting in experience/activity-dependent rewiring of neuronal circuits. In vivo Ca2+ imaging studies have revealed the distinct, input-specific response patterns of excitatory neurons in the brain. These updated in vivo approaches are just beginning to be used for the study of pathophysiological mechanisms of chronic diseases. In this paper, we introduce recent in vivo two-photon imaging studies demonstrating how plastic changes in synaptic structure and function of the mouse somatosensory cortex, following peripheral injury, contribute to chronic pain conditions, like neuropathic and inflammatory pain

Phase-specific plasticity of synaptic structures in the somatosensory cortex of living mice during neuropathic pain

<p>Abstract</p> <p>Background</p> <p>Postsynaptic dendritic spines in the cortex are highly dynamic, showing rapid morphological changes including elongation/retraction and formation/elimination in response to altered sensory input or neuronal activity, which achieves experience/activity-dependent cortical circuit rewiring. Our previous long-term <it>in vivo </it>two-photon imaging study revealed that spine turnover in the mouse primary somatosensory (S1) cortex markedly increased in an early development phase of neuropathic pain, but was restored in a late maintenance phase of neuropathic pain. However, it remains unknown how spine morphology is altered preceding turnover change and whether gain and loss of presynaptic boutons are changed during neuropathic pain.</p> <p>Findings</p> <p>Here we used short-term (2-hour) and long-term (2-week) time-lapse <it>in vivo </it>two-photon imaging of individual spines and boutons in the S1 cortical layer 1 of the transgenic mice expressing GFP in pyramidal neurons following partial sciatic nerve ligation (PSL). We found in the short-term imaging that spine motility (Δ length per 30 min) significantly increased in the development phase of neuropathic pain, but returned to the baseline in the maintenance phase. Moreover, the proportion of immature (thin) and mature (mushroom) spines increased and decreased, respectively, only in the development phase. Long-term imaging data showed that formation and elimination of boutons moderately increased and decreased, respectively, during the first 3 days following PSL and was subsequently restored.</p> <p>Conclusions</p> <p>Our results indicate that the S1 synaptic structures are rapidly destabilized and rearranged following PSL and subsequently stabilized in the maintenance phase of neuropathic pain, suggesting a novel therapeutic target in intractable chronic pain.</p

CHANGES IN RUNNING SPEED AND STEP VARIABLES MEASURED BY INERTIAL SENSORS DURING MARATHON

The purpose of this study was to quantify endurance performance for a wide range of running population bymeasuring running speed and step variables using inertial sensors during marathon. The total of ninety-one runners (71 males and 20 females) participated in this studyand step variable data was measured by attaching inertial sensor, developed by Casio, at the sacrum. Runners were classified into sub-groups (3, 4, 5 & 6), based on race time.One-way RM ANOVA witnin sub-groups showed a significant decreasein running speed, step length, andvertical oscillation through the race but step frequency remained stable for most of the runners. The Sub 3 group showed high vertical stiffness in the initial stage of the race butsignificantly decreased throughout the race. Other groups showed significant decrease in running speed but no significant change in vertical stiffness. It might suggest that good runner could adjust vertical stiffness to keep optimal step length and running speed

中長距離ランナーにおけるステップ変数と走の経済性の縦断的変化の関係

Step parameters are associated with running economy (RE), but the relationship between these longitudinal changes remains unclear. In the present study, we aimed to clarify the relationship between changes in step parameters and RE at intensities below and above the lactate threshold (LT) in well-trained middle to long-distance runners and to acquire knowledge applicable to coaching. A total of 29 male university students training in distance running (age, 19.4 ± 1.0 yr; height, 171.3 ± 4.5 cm; body weight, 57.1 ± 3.6 kg) participated in the study. Participants performed multistage incremental treadmill tests to measure step parameters (ground contact time: CT; step length: SL; step frequency: SF; leg stiffness: kleg) and RE before and after 4 months of training. Since the LT speed of participants was 16.6 ± 1.1 km･h−1, intensities below, near, and above the LT were set at 13.8 and 15.0 km･h−1, 16.2 km･h−1, and 17.4 and 18.6 km･h−1, respectively. No significant relationships were observed between changes in RE and any of the step parameters at intensities below and near the LT. Moreover, although no significant relationship was noted between changes in RE and both SL and SF, there was a significant positive and negative relationship between changes in RE and CT and kleg, respectively, at intensities above the LT. Changes in kleg showed a strong negative correlation with CT changes at each intensity. It can be concluded from these findings that shortening the CT improves the RE for high-intensity running and that this variation is partly attributable to the improvement in kleg

Von Wiedergängern und anderen Zeitgenossen. zur Prosa Gyrdir Elíassons

NK cells play a critical role in host defense against viruses. In this study, we investigated the role of NKG2D in the expansion of NK cells after mouse CMV (MCMV) infection. Wild-type and NKG2D-deficient (Klrk1-/- ) Ly49H+ NK cells proliferated robustly when infected with MCMV strains engineered to allow expression of NKG2D ligands, which enhanced the response of wild-type NK cells. Naive NK cells exclusively express NKG2D-L, which pairs only with DAP10, whereas NKG2D-S expressed by activated NK cells pairs with DAP10 and DAP12, similar to Ly49H. However, NKG2D alone was unable to drive robust expansion of Ly49H- NK cells when mice were infected with these MCMV strains, likely because NKG2D-S was only transiently expressed postinfection. These findings demonstrate that NKG2D augments Ly49H-dependent proliferation of NK cells; however, NKG2D signaling alone is inadequate for expansion of NK cells, likely due to only transient expression of the NKG2D-DAP12 complex

脳外科病棟でのMRSAの感染管理について

脳血管障害患者の入院する病棟で喀疾よりメチシリン耐性黄色ブドウ球菌（MRSA）を検出した8例について院内感染対策について検討した．病床環境，医療従事者のMRSAによる汚染，患者の栄養状態を調査した．MRSA41株について保菌者の菌と環境菌との関係をPFGEのゲゲノムタイピングを行った．5ゲノムタイプに分類された．その結果，患者の喀疾により，常時病室環境・医療従事者は菌により汚染している．そのため日常的な感染対策をとる必要があると再確認できた．Infection control was examined for 8 examples in which MRSA (Methycilin-Resistant Staphylococcus Aurous) from squint was detected in a neurosurgical ward. The stamp method was utilized for this MRSA infection research and analysis. Samples were gathered from a ward, patient environment and medical staff uniforms. After those samples were collected, they were cultivated and identified. In addition, a patient nutritional conditions were examined to evaluate the infection control. In order to identify the level of infection in patient environment, the PFGE genome typing was implemented for 41 MRSA stumps. The results were categorized into 5 genome types. The results suggested that a room environment and medical staff were infected by MRSA from patient squint. We were able to reconfirm that a daily infection measure and infection control need to be work out