Effect of preconditioning on propofol-induced neurotoxicity during the developmental period.

At therapeutic concentrations, propofol (PPF), an anesthetic agent, significantly elevates intracellular calcium concentration ([Ca2 +]i) and induces neural death during the developmental period. Preconditioning enables specialized tissues to tolerate major insults better compared with tissues that have already been exposed to sublethal insults. Here, we investigated whether the neurotoxicity induced by clinical concentrations of PPF could be alleviated by prior exposure to sublethal amounts of PPF. Cortical neurons from embryonic day (E) 17 Wistar rat fetuses were cultured in vitro, and on day in vitro (DIV) 2, the cells were preconditioned by exposure to PPF (PPF-PC) at either 100 nM or 1 µM for 24 h. For morphological observations, cells were exposed to clinical concentrations of PPF (10 µM or 100 µM) for 24 h and the survival ratio (SR) was calculated. Calcium imaging revealed significant PPF-induced [Ca2+]i elevation in cells on DIV 4 regardless of PPF-PC. Additionally, PPF-PC did not alleviate neural cell death induced by PPF under any condition. Our findings indicate that PPF-PC does not alleviate PPF-induced neurotoxicity during the developmental period.

Water Depletion Enhanced by Halogenation of Benzene.

The pressure dependence of the solubility of hydrophobic solutes in aqueous solutions is equivalent to volume changes upon hydrophobic hydration. This phenomenon has been attributed to the packing effects induced by the van der Waals volume difference between the solute and water. However, the volume changes may also be related to the chemical properties of the solute. In this study, we investigated hydrophobic hydration using a series of halogenated benzenes. Solution density measurements revealed negative volume changes for benzene, fluorobenzene, and chlorobenzene, whereas those for bromobenzene and iodobenzene were positive. Subsequent volumetric analyses demonstrated that the relationship between the excess particle number for hydration water and the van der Waals volume for bromobenzene and iodobenzene significantly deviated from the universal line for hydrophobic solutes. This behavior suggests that the volume changes are due to factors other than the packing effect with bromo and iodine functional groups acting as modulators of the hydration structure, resulting in enhanced water depletion.

Intravenous anesthetic-induced calcium dysregulation and neurotoxic shift with age during development in primary cultured neurons.

Anesthetic-induced neurotoxicity in the developing brain is a concern. This neurotoxicity is closely related to anesthetic exposure time, dose, and developmental stages. Using calcium imaging and morphological examinations in vitro, we sought to determine whether intravenous anesthetic-induced direct neurotoxicity varies according to different stages of the days in vitro (DIV) of neurons in primary culture. Cortical neurons from E17 Wistar rats were prepared. On DIV 3, 7, and 13, cells were exposed to the intravenous anesthetics thiopental sodium (TPS), midazolam (MDZ), or propofol (PPF), to investigate direct neurotoxicity using morphological experiments. Furthermore, using calcium imaging, the anesthetic-induced intracellular calcium concentration ([Ca2+]i) elevation was monitored in cells on DIV 4, 8, and 13. All anesthetics elicited significant [Ca2+]i increases on DIV 4. While TPS (100 µM) and MDZ (10 µM) did not alter neuronal death, PPF (10 µM and 100 µM) decreased the survival ratio (SR) significantly. On DIV 8, TPS and MDZ did not elicit [Ca2+]i elevation or SR decrease, while PPF still induced [Ca2+]i elevation (both at 10 µM and 100 µM) and significant SR decrease at 100 µM (0.76 ± 0.03; P < 0.05), but not at 10 µM (0.91 ± 0.03). Such anesthetic-induced [Ca2+]i elevation and SR decrease were not observed on DIV 13-14 for any of the anesthetic drugs. Our study indicates that more caution may be exercised when using PPF compared to TPS or MDZ during development.

Hydration Promoted by a Methylene Group: A Volumetric Study on Alkynes in Water.

Hydrocarbons including a methylene group are generally considered a hydrophobic building block, in the sense that the density of their hydration water is lower than that of bulk water. However, is the methylene group always hydrophobic? In this study, we experimentally determined the partial molar volume of a methylene group in water as 14.01 ± 0.46 cm3 mol-1 for 1-alkyne, 9.83 ± 0.35 cm3 mol-1 for 2-alkyne, and 11.39 ± 0.55 cm3 mol-1 for 3-alkyne. These values are all unusually small compared to the ∼16 cm3 mol-1 for model compounds from the literature. The subsequent volumetric analysis on the basis of the Kirkwood-Buff parameter indicates that the hydration water is enriched by the addition of a methylene group for 2-alkyne, while it is depleted for the reported model compounds that contain hydrophilic functional groups, 1-alkyne, and 3-alkyne. Our findings suggest that the triple bonded carbons in 2-alkyne that reduce hydration water act as a hydrophobic group in 2-alkyne. Thus, the methylene group should be called "hydrophilic" in this case because it actually recovers the hydration water when placed next to more hydrophobic groups. Therefore, we conclude that the hydrophobicity of a methylene group varies depending on its hydration environment due to other functional groups in the solute.

Thiopental sodium preserves the responsiveness to glutamate but not acetylcholine in rat primary cultured neurons exposed to hypoxia.

Although many in vitro studies demonstrated that thiopental sodium (TPS) is a promising neuroprotective agent, clinical attempts to use TPS showed mainly unsatisfactory results. We investigated the neuroprotective effects of TPS against hypoxic insults (HI), and the responses of the neurons to l-glutamate and acetylcholine application. Neurons prepared from E17 Wistar rats were used after 2weeks in culture. The neurons were exposed to 12-h HI with or without TPS. HI-induced neurotoxicity was evaluated morphologically. Moreover, we investigated the dynamics of the free intracellular calcium ([Ca(2+)]i) in the surviving neurons after HI with or without TPS pretreatment following the application of neurotransmitters. TPS was neuroprotective against HI according to the morphological examinations (0.73±0.06 vs. 0.52±0.07, P=0.04). While the response to l-glutamate was maintained (0.89±0.08 vs. 1.02±0.09, P=0.60), the [Ca(2+)]i response to acetylcholine was notably impaired (0.59±0.02 vs. 0.94±0.04, P<0.01). Though TPS to cortical cultures was neuroprotective against HI morphologically, the [Ca(2+)]i response not to l-glutamate but to acetylcholine was impaired. This may partially explain the inconsistent results regarding the neuroprotective effects of TPS between experimental studies and clinical settings.

Only extra-high dose of ketamine affects l-glutamate-induced intracellular Ca(2+) elevation and neurotoxicity.

The neurotoxic effects of anesthetics on the developing brain are a concern. Although most of the anesthetics are GABAA agonists or NMDA antagonists, the differences in these effects on prospective glutamate-neurotoxicity in the brain is not fully understood. We examined the degree of L-glutamate-induced intracellular calcium ([Ca(2+)]i) elevation and neurotoxicity in neurons exposed to anesthetics. Primary cortical neurons from E17 rats were preincubated with 1-100 µM of ketamine or thiopental sodium (TPS) for the first 72 h of culturing. Two weeks later, the neurons were exposed to L-glutamate. The extent of glutamate toxicity was evaluated using Ca(2+)-imaging and morphological experiments. Preincubation with 100 µM ketamine but not with other concentrations of ketamine and TPS for the first 72 h in culture significantly enhanced L-glutamate-induced [Ca(2+)]i elevation 2 weeks later. Morphology experiments showed that vulnerability to L-glutamate-mediated neurotoxicity was only altered in neurons preincubated with 100 µM ketamine but not with TPS. Although preincubation with high concentration of ketamine showed enhancement of L-glutamate-induced [Ca(2+)]i elevation 2 weeks later, long-term exposure to TPS or ketamine at clinical doses during developmental periods may not result in a dose-related potentiation of exogenous glutamate-induced neurotoxicity, once the intravenous anesthetics are discontinued.

Transversus abdominis plane block for bilateral orchiopexy in an 8-year-old patient with Eisenmenger's syndrome.

Non-cardiac surgery should only be performed in patients with Eisenmenger's syndrome if absolutely mandatory because these patients are at high risk of perioperative mortality. Proper anesthetic and perioperative pain management in these patients remains a controversial topic. Transversus abdominis plane (TAP) block provides safe and beneficial perioperative analgesia in adults and children; however, no report has described the performance of TAP block in a child with Eisenmenger's syndrome. Herein, we describe the performance of bilateral orchiopexy for cryptorchidism in an 8-year-old boy with Eisenmenger's syndrome due to an uncorrected muscular ventricular septal defect (mVSD). Anesthesia induction and maintenance were uneventful. Subsequently, the patient received ultrasound-guided bilateral TAP block by using 10 mL of 0.25 % levobupivacaine shortly before recovery from anesthesia. The TAP block provided pain relief and maintenance of stable hemodynamics during the postoperative period. We successfully used a TAP block in a child with Eisenmenger's syndrome to provide postoperative analgesia. No side effects were apparent during the perioperative period. TAP block can be considered a beneficial pain management technique for analgesia in children with Eisenmenger's syndrome.

The influence of initial target effect-site concentrations of propofol on the similarity of effect-sites concentrations at loss and return of consciousness in elderly female patients with the Diprifusor system.

BACKGROUND: Whether effect-site concentrations of propofol (Cep) at loss of consciousness and return of consciousness (LOC and ROC, respectively) in elderly women using Diprifusor are similar is unclear. We investigated whether differences in initial target Cep (Ctarget) alter similarities between Cep values at LOC and ROC. MATERIALS AND METHODS: In this study, female patients (n = 58, age = 72.5 ± 1.1 years) undergoing knee arthroplasty were administered propofol with Diprifusor. Cep at LOC and ROC were estimated for different Ctarget values (3.0-4.5 µg/ml). Pearson's correlation coefficient analysis and simple regression were performed to assess the relationship between Cep at LOC and ROC for each Ctarget. Differences in correlation coefficients of regression lines obtained from each Ctarget group were determined using the t-test. RESULTS: The different Ctarget groups did not show significant differences in total propofol levels and in Cep values at LOC or ROC. However, Cep at ROC was significantly higher than Cep at LOC when Ctarget was 4.0 and 4.5 µg/ml, whereas these Cep values were not significantly different in low Ctarget groups. Strong positive correlations were observed between Cep at LOC and ROC for all Ctarget groups. Regression coefficients for the different Ctarget groups were not significantly different. Compared to low (≤3.5 µg/ml) Ctarget groups, high Ctarget groups showed significantly shorter time until LOC. Induction quality was not significantly different among the groups. CONCLUSIONS: In elderly women, Cep values at LOC are strong predictors of Cep at ROC when Ctarget is 3.0-4.5 µg/ml. High Ctarget groups (≥4.0 µg/ml) exhibited shorter induction times with normal cardiovascular stability.

Undiagnosed thyrotoxicosis in a pregnant woman with spontaneous renal artery aneurysm rupture.

Renal artery aneurysm (RAA) rupture during pregnancy is a rare event which is associated with high mortality rates for both mother and fetus. Hyperthyroidism may be present during pregnancy. Both complications are easily confused with more common conditions. We report an unusual case of a pregnant woman with undiagnosed hyperthyroidism and spontaneous RAA rupture. Thyroid storm may have been precipitated by the RAA rupture; however, the diagnosis was delayed because signs and symptoms were mistaken for those of hypovolemia. The possibility of thyrotoxicosis should be considered when mental status changes and tachycardia persist after the treatment of hypovolemic shock.

The neuroprotective effect of ONO-1714 on NMDA-mediated cytotoxicity in vitro.

We report the effects of a newly developed NOS inhibitor on the neurotoxicity induced by NMDA on cultured fetal rat cortical neurons. To date, three different isoforms of NOS have been characterized. It has been considered that both neuronal NOS and inducible NOS activities are detrimental to the ischemic brain, whereas endothelial NOS plays a prominent role in maintaining cerebral blood flow and prevents neuronal injury during ischemia. ONO-1714 is a newly developed competitive NOS inhibitor that has selective inhibitory potency for iNOS than eNOS. However, its effect on nNOS has not been investigated yet. In this study, we investigated the neuroprotective effect of ONO-1714 on NMDA-induced neurotoxicity in our established model of primary cultured cortical neurons of rat foetus. Cortical neurons (prepared from E16 rat foetuses) were used after 13-14 days in culture. The cells were exposed to 30 muM NMDA for 24 h in the culture. To evaluate the neuroprotective effects of NOS inhibitors, ONO-1714 and L-NAME, neurons were exposed to various concentrations of an NOS inhibitor with 30 muM NMDA. The NMDA induced neurotoxicity was significantly attenuated by ONO-1714 in all concentrations, but not in low to moderate concentrations of L-NAME. These findings demonstrate that the neuroprotective effect of ONO-1714 was more potent than L-NAME. Moreover, ONO-1714 has a strong inhibitory effect on nNOS and would be a powerful tool for the protection of neurons against cerebral ischemia.

Effects of deep hypothermia on nitric oxide-induced cytotoxicity in primary cultures of cortical neurons.

Nitric oxide (NO) is thought to play a major role during cerebral ischemia. However, the protective efficacy of hypothermia against NO-induced neurotoxicity remains to be examined. In the present study, the degree of neurotoxicity induced by NO was analyzed in two temperature groups (normothermia, 37 degrees C; deep hypothermia, 22 degrees C) of cultured E16 Wistar rat cortical neurons. Two different NO donors, 1-hydroxy-2-oxo-3-(N-ethyl-2-aminoethyl)-3-ethyl-1-triazene (NOC-12) and 1-hydroxy-2-oxo-3-(3-amynopropyl)-3-isopropyl-1-triazene (NOC-5), that have equal half-lives at 37 degrees C and 22 degrees C, respectively, were used. Cultured neurons in each temperature group were exposed to 30 and 100 micro M NOC for three different time courses, 6 hr, 12 hr, and 24 hr. The survival rates of neurons were evaluated by assessing viable neurons on photomicrographs before and after the experiments. The highest survival rate (approximately 93%) was seen in both temperature groups when neurons were exposed to 30 micro M NOC for 6 hr and 12 hr, and there was no significant difference observed between these two groups (P > 0.05). Almost equal survival rates were observed in both temperature groups following exposure to 30 micro M NOC for 24 hr (at 37 degrees C, 80.4% +/- 2.6%; at 22 degrees C, 83.2% +/- 1.6%; P > 0.05). During exposure to 100 micro M NOC, although the survival rate linearly decreased (approximately from 70% to 5%) in both temperature groups when exposed for 6-24 hr, there were no significant intergroup differences observed (P > 0.05). In conclusion, hypothermia does not provide adequate protection to the neurons by acting on the mechanisms evoked by NO, so we speculate that hypothermia may not confer neuroprotetcion once NO is released during ischemia.

Hypothermia and thiopentone sodium: individual and combined neuroprotective effects on cortical cultures exposed to prolonged hypoxic episodes.

Because there are many conflicting reports on cerebroprotective effects of hypothermia and barbiturates, we examined the degree of neuroprotection at defined temperatures (normothermia, 37 degrees C; mild hypothermia, 32 degrees C; deep hypothermia, 22 degrees C; and profound hypothermia, 17 degrees C) and various concentrations (low, 4 microM; moderate, 40 microM; and high, 400 & microM) of thiopentone sodium (TPS), alone and in combination in cortical cultures exposed to prolonged hypoxia (24-48 hr). The survival rate of embryonic day (E)16 Wistar rat cortical neurons was evaluated on photomicrographs before and after experiments. During the 24-hr hypoxic period, the survival rate of neurons was maximal with combinations of mild hypothermia with 40 microM (91.6 +/- 0.7%) and 400 microM TPS (90.8 +/- 0.7%) or deep hypothermia combined with all concentrations of TPS (4 microM, 90.6 +/- 1.0%; 40 microM, 91.4 +/- 0.8%; 400 microM, 91.8 +/- 1.2%). During 48 hr hypoxia, the highest survival rate was seen with the combination of deep hypothermia and either 40 microM (90.9 +/- 0.6%) or 400 microM (91.1 +/- 1.4%) TPS. In the presence of profound hypothermia in combination with all concentrations of TPS, the survival rate was significantly reduced (P< 0.01) compared to combined application of either mild or deep hypothermia with TPS. In summary, maximal neuroprotection was attained with hypothermia and TPS in combination rather than applied individually, during prolonged hypoxic episodes (24- 48 hr). During a 24-hr hypoxic period, both mild and deep hypothermia combined with a clinically relevant concentration of TPS (40 microM) offered the highest neuroprotection. Only deep hypothermia provided maximal neuroprotection when combined with 40 microM TPS, during 48-hr hypoxia. Combination of profound hypothermia and TPS did not confer considerable neuroprotection during long lasting hypoxia.