Go Hirabayashi

Probing the molecular mechanisms of neuronal degeneration: importance of mitochondrial dysfunction and calcineurin activation

Cerebral injury is a critical aspect of the management of patients in intensive care. Pathological conditions induced by cerebral ischemia, hypoxia, head trauma, and seizure activity can result in marked residual impairment of cerebral function. We have investigated the potential mechanisms leading to neuronal cell death in pathological conditions, with the aim of discovering therapeutic targets and methods to minimize neuronal damage resulting from insults directed at the central nervous system (CNS). Over the years, deeper understanding of the mechanisms of neuronal cell death has indeed evolved, enabling clinical critical care management to salvage neurons that are at the brink of degeneration and to support recovery of brain function. However, no substantial breakthrough has been achieved in the quest to develop effective pharmacological neuroprotective therapy directed at tissues of the CNS. The current situation is unacceptable, and preservation of function and protection of the brain from terminal impairment will be a vital medical issue in the twenty-first century. To achieve this goal, it is critical to clarify the key mechanisms leading to neuronal cell death. Here, we discuss the importance of the calcineurin/immunophilin signal transduction pathway and mitochondrial involvement in the detrimental chain of events leading to neuronal degeneration.

Effects of temperature gradient reduction in three different carbon dioxide absorbents.

Background and objective Temperature gradients in CO2 absorbents may locally increase the water content by condensation. We hypothesized that temperature gradient reduction (TGR) would prevent increased water content, thus preserving the reactivity of the CO2 absorbent and thereby increasing its time to exhaustion (longevity). The purpose of this study was to compare the effects of TGR on the longevity of CO2 absorbent with three different types of CO2 absorbents. Methods We constructed a novel TGR canister. Experiments were conducted using three different types of CO2 absorbents: Drägersorb 800 Plus (D800), Drägersorb Free and Amsorb Plus. One kilogram of fresh CO2 absorbent of each type was placed into two types of canister: the conventional control canister (n = 6) and the TGR canister (n = 6). Results In the case of Drägersorb Free, the TGR canister most effectively and specifically prevented local increase in water content of the CO2 absorbent and markedly increased the longevity (30% increase) compared with the control canister. In the case of Amsorb Plus, the TGR canister also prevented local excessive water content, but the increase in longevity was smaller (17% increase). In the case of D800, the TGR canister markedly increased the longevity (27% increase), but its prevention of local excessive water content was smaller. Conclusions TGR is a useful method to prevent local increase in water content and improve the longevity of CO2 absorbent. The effectiveness of TGR on longevity and water content changes varied in the different types of CO2 absorbent.

Usefulness of galvanic skin reflex monitor in CT-guided thoracic sympathetic blockade for palmar hyperhidrosis

Computed tomography (CT)-guided thoracic sympathetic blockade with ethanol was performed while monitoring sympathetic nerve activity, with an alternating current (AC) galvanic skin reflex (GSR) monitor, in a patient with palmar hyperhidrosis in whom endoscopic thoracic sympathectomy was impossible because of pleural adhesion. Sweating was suppressed after the thoracic sympathetic blockade, and the monitor showed a significant increase in skin resistance. The effect of sympathetic blockade could be evaluated directly and in real time using a GSR monitor.

Inadequate gas supply to patients with an adjustable pressure-limiting valve in the fully opened position

With spontaneous ventilation, sufficient exhaust resistance at the adjustable pressure-limiting (APL) valve when fully opened ensures that the reservoir bag fills and adequately supplies gas to patients. A lack of exhaust resistance with the APL valve fully open caused inadequate gas supply to patients with four types of anesthesia machines: SA2 (Dräger), Excel-210 SE (GE), Fabius (Dräger), and Cato (Dräger). Mechanically, the SA2 and Excel-210 SE APL valve systems, which are of the spring-loaded disc type positioned horizontally, cannot maintain sufficient exhaust resistance with the APL valve fully open. As for the Fabius and Cato, an exhaust valve independent of the APL valve should maintain sufficient exhaust resistance continuously. However, accumulated viscous substances on the thin diaphragm of the exhaust valve contributed to hindrance of diaphragm closure.