Phosphatidylinositol-3,4,5-trisphosphate (PtdInsP(3)) regulates diverse cellular functions, including cell proliferation and apoptosis, and has roles in the progression of diabetes and cancer. However, little is known about its production. Here, we describe fluorescent indicators for PtdInsP(3) that allow a spatio-temporal examination of PtdInsP(3) production in single living cells. After ligand stimulation, PtdInsP(3) levels increased to a larger extent at the endomembranes (that is, the endoplasmic reticulum and the Golgi) than at the plasma membrane. This increase was found to originate from in situ production at the endomembranes, a process stimulated directly by receptor tyrosine kinases endocytosed from the plasma membrane to the endomembranes. The demonstration of PtdInsP(3) production through receptor endocytosis addresses a long-standing question about how signalling pathways downstream of PtdInsP(3) are activated at intracellular compartments remote from the plasma membrane.

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Elbow valgus load generated in baseball pitching is a risk factor for throwing-related injuries. However, an induced acceleration analysis establishing the cause-effect relationship between elbow valgus load and causal joint kinematics is lacking. The purpose of this study was to identify the underlying mechanism of how the elbow valgus load is generated by muscular and non-muscular interactive torque effects. The throwing motions of five fastball pitches from 16 male collegiate baseball pitchers were measured by a three-dimensional motion capture system. The induced acceleration analysis developed in this study was used to separate the elbow valgus stress of the throwers into causal muscular and interactive torque components. The results showed that the shoulder internal rotation torque-induced component was greatest, accounting for 73.0% of the valgus-related contribution, while the other joint components in the muscular and interactive torque components were relatively smaller. This implied that the elbow valgus stress was highly influenced by the internal rotation torque effect, while the motion-dependent effect due to the trunk and shoulder kinematics was not influential. In conclusion, to reduce the risk of injury, pitchers should acquire proper coordination without excessive shoulder internal rotation action.

The aim of this study was to investigate the kinematic characteristics of batting motions for the different speed balls. Twenty nine university baseball players volunteered as the subjects. The ball speeds were set for three conditions; slow (75-80km/h), medium (100-105km/h), and fast (125-130km/h). Three dimensional kinematic data of swing motions were collected using Vicon 612 system. Impact parameters and kinematic parameters of swing motion were analyzed. Impact angle, which was defined as the angle between the vector of bat velocity and the vector of hit ball velocity, was calculated for evaluating the hitting accuracy in both the temporal and the spatial viewpoints. The results were summarized as follows. As the ball speed was increased, The impact angle was increased. The subjects decreased the displacement of center of gravity forward to pitcher so that the time from the ball release to the ball impact would be as long as possible, and the subjects decreased the range of rotational motions of the bat and upper torso from the instant of maximum twist of the torso to the ball impact. On the other hand, the maximum twist angle of the torso joint was consistent for the various ball speeds so that the bat speed should not be decreased as the ball speed was increased.