Regulation of AQP-4 water channel expression in the brain during development and by ischemia

Water transport is mediated by two distinct pathways, diffusional and channel-mediated water transport. The first molecular water channel was identified from human erythrocytes in 1992. Genetically-related proteins from other mammalian tissues have subsequently been identified to transport water, and the group is referred to as the "Aquaporins". Aquaporin-4 (AQP4) is most abundant in the brain, which may be involved in CSF reabsorption and osmoregulation. However, ontogeny and regulatory mechanisms of AQP4 channels have not been reported. Northern blot analysis showed that AQP4 mRNA began to be expressed in the brain just before birth and that its expression gradually increased by PN7 and then decreased at adult level. AQP4 was expressed predominantly in the ependymal cells of ventricles in newborn rats. And then its expression decreased in ependymal cells and increased gradually in other regions including supraoptic and paraventricular nuclei. AQP4 is also expressed in the subfornical organ, in which the expression level is not changed after birth. Cryogenic brain injury did not affect expression of AQP4 mRNA, while ischemic brain injury decreased it. Osmotic water permeability of AQP4 channel expressed in Xenopus oocytes was inhibited by the pretreatment of BAPTA/AM and calmidazolium, a Ca2+/ Calmodulin kinase inhibitor, in a dose-dependent manner. These results indicate that the expression and the function of AQP4 channel are regulated by developmental processes and various pathophysiological conditions. These results will contribute to the understanding of fluid balance in the central nervous system and the osrmoregulatory mechanisms of the body.

The Clinical Study for Upper Respiratory Infection in Surgical Intensive Care Unit Patients with Tracheostomies / 대한마취과학회지

Infections that occur within the surgical intensive care unit represent a significant cause of patient morbidity and mortality. In addition, hospital-related infections prolong hospital stay and increase hospital-charges. Moreover for the patient with tracheostomy, the possibility of cross-infection may impose an added risk when the general condition is poor. This study was undertaken to investigate the incidence of upper respiratory infection in patients with tracheostomies who had respiratory care in the surgical intensive care unit. The total number of cases in this study was 20, and the specimens for bacteriologic culture were taken especially from the regions of the upper respiratory tract via tracheostomy tubes on the 1,3,5,7 and 10th day after tracheostomy. The results obtained from the bacteriologic culture were as follows: 1_ The most frequently found organism was Pscudomonas aeruginosa, and newxt was staphylococcus, followed by beta-hemolytic streptococcus and Escherichia coli. Gram negative bacilli were 58.9% of all cultured organisms. 2) The greatest number of organism was seen on the third day and frequency of mixed growth was increased in process of time. 3) The comparative sensitivity test of Pseudomonas seruginosa showed that all strains were resistant to ampicillin, erythromyclin, penicillin and tetracycline and 70% of strains were sensitive to amikacin.

Treatmeat of Severe Cardiac Arrhythmia due to the Inadvertent use of Large doses of Epinephrine during Operation / 대한마취과학회지

Cardiac arrhythmia frequently occurs under general anesthesia. It has been reported that cathecholamines increase the incidence of arrhythmia during anesthesia with halothane, which sensitizes the myocardium to the effects of cathecholamines. We experienced epinephrine-induced cardiac arrhythmia during anesthesia with halothane due to the inadvertent use of a large dose of epinephrine to achieve hemostasis. When the cardiac arrhythmia was noted by ECG, immediate tratment was performed and the result is summarized.