Involvement of protein kinase C and Src tyrosine kinase in acute tolerance to ethanol inhibition of spinal NMDA-induced pressor responses in rats.

BACKGROUND AND PURPOSE: The present study was carried out to examine the role of protein kinases in the development of acute tolerance to the effects of ethanol on spinal N-methyl-D-aspartate (NMDA) receptor-mediated pressor responses during prolonged ethanol exposure. EXPERIMENTAL APPROACH: Blood pressure responses induced by intrathecal injection of NMDA were recorded. The levels of several phosphorylated residues on NMDA receptor NR1 (GluN1) (NR1) and NMDA receptor NR2B (GluN2B) (NR2B) subunits were determined by immunohistochemistry and Western blot analysis. KEY RESULTS: Ethanol inhibited spinal NMDA-induced pressor responses at 10 min, but the inhibition was significantly reduced at 40 min following continuous infusion. This effect was dose-dependently blocked by chelerythrine [a protein kinase C (PKC) inhibitor, 1-1000 pmol] or PP2 (a Src family tyrosine kinase inhibitor, 1-100 pmol) administered intrathecally 10 min following ethanol infusion. A significant increase in the immunoreactivity of phosphoserine 896 of NR1 subunits (pNR1-Ser896) and phosphotyrosine 1336 of NR2B subunits (pNR2B-Tyr1336) was found in neurons of intermediolateral cell column during the development of tolerance. Levels of pNR1-Ser896 and pNR2B-Tyr1336 were also significantly increased in lateral horn regions of the spinal cord slices incubated with ethanol for 40 min in vitro. The increases in pNR1-Ser896 and pNR2B-Tyr1336 levels were inhibited by post-treatment with chelerythrine and PP2, respectively, both in the in vivo and in vitro studies. CONCLUSIONS AND IMPLICATIONS: The results suggest that activation of PKC and Src tyrosine kinase during prolonged ethanol exposure leading to increases in the levels of pNR1-Ser896 and pNR2B-Tyr1336 may contribute to acute tolerance to inhibition by ethanol of NMDA receptor function.

Hydrogen peroxide increases the activity of rat sympathetic preganglionic neurons in vivo and in vitro.

Reactive oxygen species (ROS) have been shown to modulate neuronal synaptic transmission and have also been implicated in cardiovascular diseases such as hypertension. The hypothesis that H(2)O(2) acting on sympathetic preganglionic neurons (SPNs) affects spinal sympathetic outflow was tested in the present study. H(2)O(2) was applied intrathecally via an implanted cannula to the T7-T9 segments of urethane-anesthetized rats. Blood pressure and heart rate were used as indices to evaluate the spinal sympathetic effects of H(2)O(2) in vivo. Intrathecal H(2)O(2) (100-1000 nmol) dose-dependently increased both the mean arterial pressure and heart rate. Reproducible pressor effects of H(2)O(2) (1000 nmol) applied consecutively at intervals of 30 min were observed. The pressor effects of intrathecal H(2)O(2) (1000 nmol) were attenuated by pretreatment with intrathecal administration of catalase (500 units), or N-acetyl-cysteine (1000 nmol). The pressor effects of intrathecal H(2)O(2) (1000 nmol) were also antagonized dose-dependently by prior intrathecal injection of AP-5 (DL-2-amino-5- phosphonovaleric acid, 10 and 30 nmol), or 6-cyano-7- nitroquinoxaline-2,3-dione, 10 and 30 nmol. In vitro electrophysiological study in spinal cord slices showed that superfusion of 1 mM H(2)O(2) for 3 min, which had no effect on membrane potential, caused an increase in amplitude of excitatory postsynaptic potentials in SPNs, but had little effect on that of inhibitory postsynaptic potentials. Taken together, these results demonstrated that oxidative stress in spinal cord may cause an increase in spinal sympathetic tone by acting on SPNs, which may contribute to ROS-induced cardiovascular dysfunction.

Seroprevalence of CMV antibodies in a blood donor population and premature neonates in the south-central Taiwan.

Infection of cytomegalovirus (CMV) via contaminated blood may endanger immunocompromised patients that require transfusion therapy. The aim of this study is to determine the prevalence of CMV antibodies in the blood donor population in Southern-central Taiwan. A total of 1800 consecutive sera, obtained from Tainan Blood Center of Chinese Blood Services Foundation (CBSF), were tested for CMV antibodies by two commercial enzyme immunoassays (EIAs). Of the sera tested, 150 (8.3%) were found to be CMV seronegative. The frequency of CMV seropositivity revealed no significant difference between male and female donors. The frequency of CMV seronegativity showed a stepwise decrease with the increase of donor age. In addition, the prevalence of HBsAg, antibodies to hepatitis C virus (anti-HCV), antibodies to human immunodeficiency viruses type 1 and 2 (anti-HIV 1 + 2) and antibodies to human T-cell lymphotropic viruses type I and II (anti-HTLV I/II) were compared between CMV seropositive and seronegative groups. Our results showed that there was no significant difference in seroprevalence of these markers between CMV seropositive and seronegative groups. Our findings also showed that six out of twenty (30.0%) premature neonates were CMV-seropositive. These premature specimens and those EIA discrepancy samples were confirmed by specific nucleic acid amplification using polymerase chain reaction (PCR). Our results suggest that a program which aims to supply CMV seronegative blood or blood components to the patients, should not solely depend on current antibody screening methods in an area where CMV infection is highly endemic. Amendments such as PCR testing, leukocyte reduction by filtration before transfusion may be more practical.

Antenatal diagnosis and early surgery for choledochal cyst: a report of two cases.

Since the advent of routine antenatal sonography to detect fetal abnormalities, two cases of choledochal cyst have been found prenatally in our hospital. The first presented when a choledochal cyst was demonstrated at 31 weeks of gestation, and a firm diagnosis established within 2 days of birth. Technetium 99m disofenin (DISIDA) cholescintigram revealed delayed visualization of the small bowel. The second case was found by ultrasound examination at 21 weeks of gestation to have a choledochal cyst, and diagnosis was confirmed within 3 days of birth. DISIDA scintigram demonstrated complete obstruction of the extrahepatic biliary tree. Both infants received early excision of the cyst at the ages of three and four days respectively. The postoperative course was quite smooth, and there were no abnormal symptoms after follow up of four and two years, respectively. Neonates with distal common bile duct obstruction in association with presumed choledochal cyst should have prompt surgical exploration, and early excision of the cyst is a safe procedure in the newborn.