The Validity and Reliability of a Smartphone Application for Break-Point Angle Measurement during Nordic Hamstring Exercise

# Background A recently developed smartphone application (Nordic Angle) allows the automatic calculation of the break-point angle (BPA) during Nordic hamstring exercise (NHE) without transferring the collected data to a computer. The BPA is the point at which the hamstrings are unable to withstand force. However, the validity of the BPA values obtained by this method has not been examined. # Hypothesis/Purpose This study aimed to evaluate the validity and reliability of the Nordic Angle by comparing the BPA values of the Nordic Angle with those of two-dimensional motion analysis software that can calculate the angles and angular velocities of various joints. # Study Design Cohort assessing Validity and Reliability # Methods The validity of the Nordic Angle BPA data was verified by Spearman's correlation test for consistency with the movement analysis data, and the magnitude of the correlation was indicated by rs. The agreement between these measurements was examined using the Bland-Altman analysis. The reliability of the Nordic Angle and motion analysis was examined using the intraclass correlation coefficient (ICC) (1,k) based on data from repeated trials within a day. # Results Although the spearman correlation between the Nordic angle and the angle determined using motion analysis did not reach statistical significance (p = 0.052), a very large correlation was present (rs = 0.75). The difference between the mean values of the Nordic Angle and motion analysis was 0.4 ± 2.1°, and the limits of agreement ranged from -3.9° to 4.6°. In two BPA measurements, the Nordic Angle showed perfect reliability (ICC = 1.00, p \< 0.001), while motion analysis showed nearly perfect reliability (ICC = 0.97, p \< 0.001). # Conclusion The Nordic Angle, which has both validity and reliability, may be appropriate for field measurement because it allows immediate feedback of BPA and the measurement of many athletes. # Level of evidence 3b ©The Author(s

A Transient Rise in Free Mg 2+ Ions Released from ATP-Mg Hydrolysis Contributes to Mitotic Chromosome Condensation

細胞分裂期の染色体凝縮はマグネシウムイオンの増加によって起こる --生細胞イメージングにより新たなメカニズムを検証--. 京都大学プレスリリース. 2018-01-19.For cell division, negatively charged chromatin, in which nucleosome fibers (10 nm fibers) are irregularly folded [ 1–5 ], must be condensed into chromosomes and segregated. While condensin and other proteins are critical for organizing chromatin into the appropriate chromosome shape [ 6–17 ], free divalent cations such as Mg2+ and Ca2+, which condense chromatin or chromosomes in vitro [ 18–28 ], have long been considered important, especially for local condensation, because the nucleosome fiber has a net negative charge and is by itself stretched like “beads on a string” by electrostatic repulsion. For further folding, other positively charged factors are required to decrease the charge and repulsion [ 29 ]. However, technical limitations to measure intracellular free divalent cations, but not total cations [ 30 ], especially Mg2+, have prevented us from elucidating their function. Here, we developed a Förster resonance energy transfer (FRET)-based Mg2+ indicator that monitors free Mg2+ dynamics throughout the cell cycle. By combining this indicator with Ca2+ [ 31 ] and adenosine triphosphate (ATP) [ 32 ] indicators, we demonstrate that the levels of free Mg2+, but not Ca2+, increase during mitosis. The Mg2+ increase is coupled with a decrease in ATP, which is normally bound to Mg2+ in the cell [ 33 ]. ATP inhibited Mg2+-dependent chromatin condensation in vitro. Chelating Mg2+ induced mitotic cell arrest and chromosome decondensation, while ATP reduction had the opposite effect. Our results suggest that ATP-bound Mg2+ is released by ATP hydrolysis and contributes to mitotic chromosome condensation with increased rigidity, suggesting a novel regulatory mechanism for higher-order chromatin organization by the intracellular Mg2+-ATP balance

Human AK2 links intracellular bioenergetic redistribution to the fate of hematopoietic progenitors

AK2 is an adenylate phosphotransferase that localizes at the intermembrane spaces of the mitochondria, and its mutations cause a severe combined immunodeficiency with neutrophil maturation arrest named reticular dysgenesis (RD). Although the dysfunction of hematopoietic stem cells (HSCs) has been implicated, earlier developmental events that affect the fate of HSCs and/or hematopoietic progenitors have not been reported. Here, we used RD-patient-derived induced pluripotent stem cells (iPSCs) as a model of AK2-deficient human cells. Hematopoietic differentiation from RD-iPSCs was profoundly impaired. RD-iPSC-derived hemoangiogenic progenitor cells (HAPCs) showed decreased ATP distribution in the nucleus and altered global transcriptional profiles. Thus, AK2 has a stage-specific role in maintaining the ATP supply to the nucleus during hematopoietic differentiation, which affects the transcriptional profiles necessary for controlling the fate of multipotential HAPCs. Our data suggest that maintaining the appropriate energy level of each organelle by the intracellular redistribution of ATP is important for controlling the fate of progenitor cells

Acute effects of a hop-stabilization warm-up program on dynamic balance, ground reaction force, and muscle activity during cutting movements in collegiate athletes with chronic ankle instability

International Journal of Exercise Science 17(1): 343-358, 2024. First-time lateral ankle sprains often lead to chronic ankle instability (CAI), with 47% facing recurrent injuries, emphasizing the need for preventive measures. Side-cutting movements in sports pose a risk for CAI individuals due to potential biomechanical control alterations. While the hop-stabilization warm-up program has proven effective in preventing ankle sprains, its specific acute impact on CAI individuals lacks substantial evidence. This study employed a crossover design with eight CAI participants (23 ± 3.4 years, BMI 23 ± 1.5 kg/m2) and eight healthy participants (25 ± 3.6 years, BMI 23 ± 1.7 kg/m2) to investigate the acute effects of the hop-stabilization warm-up program on dynamic balance, ground reaction force (GRF), and muscle activity during 45- and 90-degree side-cutting movements. Each participant underwent hop-stabilization and control warm-up programs on two experimental days. Assessments, including the Y-balance test, GRF, and muscle activity pre- and post-warm-up, revealed significant improvements in dynamic balance, GRF, and muscle activity during 45-degree side-cutting movements in CAI participants. These findings suggest the potential benefits of incorporating the hop-stabilization warm-up program into the warm-up protocol for individuals with CAI

Impact of dapagliflozin on left ventricular diastolic function of patients with type 2 diabetic mellitus with chronic heart failure

Abstract Background The objective of this study was to investigate the impact of sodium glucose cotransporter type 2 (SGLT2) inhibitors on left ventricular (LV) diastolic function of type 2 diabetes mellitus (T2DM) patients with heart failure (HF). Methods This trial was a prospective multicenter study of 58 T2DM patients with stable HF at five institutions in Japan. Patients who had been taking at least one antidiabetic drugs other than SGLT2 inhibitors started the administration of 5 mg/day of dapagliflozin. The physical examinations, blood tests, and echocardiography were performed at baseline and 6 months after administration of dapagliflozin. The primary endpoint was defined as a change in mitral inflow E and mitral e′ annular velocities (E/e′) between baseline and 6 months after the administration of dapagliflozin. The secondary end points consisted of a change in brain natriuretic peptide (BNP), LV mass index (LVMI) and left atrial volume index (LAVI). Results E/e′ significantly decreased from 9.3 to 8.5 cm/s (p = 0.020) 6 months after administration of dapagliflozin. LAVI and LVMI significantly decreased from 31 to 26 mL/m2 (p = 0.001), and from 75.0 to 67.0 g/m2 (p < 0.001), respectively, 6 months after administration of dapagliflozin. No significant change was observed in BNP (from 27.9 to 28.9 pg/mL; p = 0.132) 6 months after administration of dapagliflozin, except for a significant decrease from 168.8 to 114.3 pg/mL (p = 0.012) in patients with BNP ≥ 100 pg/mL. Conclusion This prospective multicenter trial showed the beneficial effect of SGLT2 inhibitors on LV diastolic functional parameters for T2DM patients with HF. Our findings may thus offer a new insight into the management of T2DM patients. Trial registration UMIN000019789, Registered 28 September 2014, Date of registration: 11/14/2015, Date of enrolment of the first participant to the trial: 6/15/2016, Date of enrolment of the last participant to the trial: 12/9/201

Changes in the Charged Metabolite and Sugar Profiles of Pasteurized and Unpasteurized Japanese Sake with Storage

Japanese sake (rice wine) is commonly heat treated (pasteurized) to maintain its quality. In this study, temporal changes in the metabolite profiles of pasteurized and unpasteurized sake were investigated during storage. Metabolomic analyses were conducted for eight sets of pasteurized and unpasteurized sake obtained from single process batches stored at 8 or 20 °C for 0, 1, 2, or 4 months. Capillary electrophoresis time-of-flight mass spectrometry and liquid chromatography tandem mass spectrometry were used to obtain charged metabolite and sugar profiles, respectively. The total amino acid concentration decreased with storage, and the decrease was faster in pasteurized sake than in unpasteurized. The organic acid concentrations were relatively constant in both types of sake. Peptide and glucose concentrations increased and polysaccharide concentrations decreased in unpasteurized sake, while they were relatively constant in pasteurized sake. Rather than stabilizing the sake metabolite profile during storage, pasteurization results in characteristic changes compared to unpasteurized sake