Adv Exp Med Biol
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Taurine is an inhibitory neurotransmitter and is one of the most abundant amino acids present in the mammalian nervous system. Taurine has been shown to provide protection against neurological diseases, such as Huntington's disease, Alzheimer's disease, and stroke. Ischemic stroke is one of the leading causes of death and disability in the world. ⋯ Moreover, taurine could downregulate the ratio of cleaved ATF6 and full-length ATF6 in both models. In the animal model of stroke, taurine induced an upregulation of the Bcl-2/Bax ratio and downregulation of caspase-3 protein activity indicating that it attenuates apoptosis in the core of the ischemic infarct. Our results show not only taurine elicits neuroprotection through the activation of the ATF6 and the IRE1 pathways, but also it can reduce apoptosis in these models.
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Comparative Study
Effect of spinal anesthesia for elective cesarean section on cerebral blood oxygenation changes: comparison of hyperbaric and isobaric bupivacaine.
We used near-infrared spectroscopy (NIRS) to evaluate cerebral blood oxygenation changes in subjects undergoing cesarean section under spinal anesthesia (SP) with hyperbaric bupivacaine (group H, 27 subjects) or isobaric bupivacaine (group I, 15 subjects). In group H, total-Hb, oxy-Hb, and mean blood pressure (MBP) within 20 min after SP were significantly lower than the baseline values. ⋯ There was no significant change of deoxy-Hb, tissue oxygen index, or heart rate from baseline in either of the groups. These results suggest that isobaric bupivacaine may be superior to hyperbaric bupivacaine for preventing a decrease of maternal cerebral blood flow after SP for cesarean section.
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Neonates supported on extracorporeal membrane oxygenation (ECMO) are at high risk of brain injury due to haemodynamic instability. In order to monitor cerebral and peripheral (muscle) haemodynamic and oxygenation changes in this population we used a dual-channel near-infrared spectroscopy (NIRS) system. In addition, to assess interrelations between NIRS and systemic variables, collected simultaneously, canonical correlation analysis (CCA) was employed. ⋯ In four out of five patients, systemic variables were found to be less inter-related with cerebral rather than peripheral NIRS measurements. Moreover, during ECMO flow manipulations, we found that the interrelation between the systemic and the NIRS cerebral/peripheral variables changed. The CCA method presented here can be used to assess differences between NIRS cerebral and NIRS peripheral responses due to systemic variations which may be indicative of physiological differences in the mechanisms that regulate oxygenation and/or haemodynamics of the brain and the muscle.
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Recently, deoxygenated hemoglobin (HHb) has been used as one of the most popular indicators of muscle O2 extraction during exercise in the field of exercise physiology. However, HHb may not sufficiently represent muscle O2 extraction, as total hemoglobin (tHb) is not stable during exercise. The purpose of this study was to measure various muscle oxygenation signals during cycle exercise and clarify which is the best indicator of muscle O2 extraction during exercise using NIRS. ⋯ During moderate exercise, tHb, O2-Hb, and SmO2 displayed progressive increases until the end of exercise. In contrast, HHb remained stable during moderate work rate. sBF remained stable during moderate exercise but showed a progressive decrease at heavy work rate. These results provide evidence that HHb may not sufficiently represent muscle O2 extraction since tHb is not stable during exercise and HHb is insensitive to exercise-induced hyperaemia.
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Extracorporeal membrane oxygenation can potentially affect cerebral blood flow dynamics and consequently influence cerebral autoregulation. We applied wavelet cross-correlation (WCC) between multichannel cerebral oxyhemoglobin concentration (HbO(2)) and mean arterial pressure (MAP), to assess regional variations in cerebral autoregulation. Six infants on veno-arterial (VA) ECMO were studied during sequential changes in the ECMO flows. ⋯ During changes in ECMO flow, statistically significant differences in maximum WCC were found between right and left hemispheres. WCC between HbO(2) and MAP provides a useful method to investigate the dynamics of cerebral autoregulation during ECMO. Manipulations of ECMO flows are associated with regional changes in cerebral autoregulation which may potentially have an important bearing on clinical outcome.