Search

Excess glutamate in the brain is thought to be implicated in the pathophysiology of fetal anoxic brain injury, yet little is known about the mechanisms by which glutamate is regulated in the fetal brain. This study examines whether there are differences between maternal and fetal glutamate concentrations, and whether a correlation between them exists.10 ml of venous blood was extracted from 87 full-term (37 weeks gestation) pregnant women in active labor. Immediately after delivery of the neonate, 10 ml of blood from the umbilical artery and vein was extracted. Samples were analyzed for levels of glutamate, glutamate-oxaloacetate transaminase (GOT), and glutamate pyruvate transaminase (GPT).Fetal blood glutamate concentrations in both the umbilical artery and vein were found to be significantly higher than maternal blood (p0.001). Similarly, fetal serum GOT levels in the umbilical artery and vein were found to be significantly higher than maternal GOT levels (p0.001). The difference in GPT levels between maternal and fetal serum was not statistically significant. There was no difference in fetal glutamate, GOT or GPT between the umbilical artery and vein. There was an association observed between glutamate levels in maternal blood and glutamate levels in both venous (R=0.32, p0.01) and arterial (R=0.33, p0.05) fetal blood.This study demonstrated that higher baseline concentrations of blood glutamate are present in fetal blood compared with maternal blood, and this was associated with elevated GOT, but not GPT levels. An association was observed between maternal and fetal blood glutamate levels.

Brain insults are characterized by a multitude of complex processes, of which glutamate release plays a major role. Deleterious excess of glutamate in the brain’s extracellular fluids stimulates glutamate receptors, which in turn lead to cell swelling, apoptosis, and neuronal death. These exacerbate neurological outcome. Approaches aimed at antagonizing the astrocytic and glial glutamate receptors have failed to demonstrate clinical benefit. Alternatively, eliminating excess glutamate from brain interstitial fluids by making use of the naturally occurring brain-to-blood glutamate efflux has been shown to be effective in various animal studies. This is facilitated by gradient driven transport across brain capillary endothelial glutamate transporters. Blood glutamate scavengers enhance this naturally occurring mechanism by reducing the blood glutamate concentration, thus increasing the rate at which excess glutamate is cleared. Blood glutamate scavenging is achieved by several mechanisms including: catalyzation of the enzymatic process involved in glutamate metabolism, redistribution of glutamate into tissue, and acute stress response. Regardless of the mechanism involved, decreased blood glutamate concentration is associated with improved neurological outcome. This review focuses on the physiological, mechanistic and clinical roles of blood glutamate scavenging, particularly in the context of acute and chronic CNS injury. We discuss the details of brain-to-blood glutamate efflux, auto-regulation mechanisms of blood glutamate, natural and exogenous blood glutamate scavenging systems, and redistribution of glutamate. We then propose different applied methodologies to reduce blood and brain glutamate concentrations and discuss the neuroprotective role of blood glutamate scavenging.

Traumatic brain injury (TBI) and stroke lead to elevated levels of glutamate in the brain that negatively affect the neurological outcomes in both animals and humans. Intravenous administration of glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) enzymes can be used to lower the blood glutamate levels and to improve the neurological outcome following TBI and stroke. The objective of this study was to analyze the pharmacokinetics and to determine the glutamate-lowering effects of GOT and GPT enzymes in naïve rats. We determined the time course of serum GOT, GPT, and glutamate levels following a single intravenous administration of two different doses of each one of the studied enzymes. Forty-six male rats were randomly assigned into one of 5 treatment groups: saline (control), human GOT at dose 0.03 and 0.06 mg/kg and porcine GPT at dose 0.6 and 1.2 mg/kg. Blood samples were collected at baseline, 5 min, and 2, 4, 8, 12, and 24 h after the drug injection and GOT, GPT and glutamate levels were determined. The pharmacokinetics of both GOT and GPT followed one-compartment model, and both enzymes exhibited substantial glutamate-lowering effects following intravenous administration. Analysis of the pharmacokinetic data indicated that both enzymes were distributed predominantly in the blood (central circulation) and did not permeate to the peripheral organs and tissues. Several-hour delay was present between the time course of the enzyme levels and the glutamate-lowering effects (leading to clock-wise hysteresis on concentration-effect curves), apparently due to the time that is required to affect the pool of serum glutamate. We conclude that the interaction between the systemically-administered enzymes (GOT and GPT) and the glutamate takes place in the central circulation. Thus, glutamate-lowering effects of GOT and GPT apparently lead to redistribution of the excess glutamate from the brain's extracellular fluid into the blood and can reduce secondary brain injury due to glutamate neurotoxicity. The outcomes of this study regarding the pharmacokinetic and pharmacodynamic properties of the GOT and GPT enzymes will be subsequently verified in clinical studies that can lead to design of effective neuroprotective treatment strategies in patients with traumatic brain diseases and stroke.

Blood glutamate scavengers have been shown to effectively reduce blood glutamate concentrations and improve neurological outcome after traumatic brain injury and stroke in rats. This study investigates the efficacy of blood glutamate scavengers oxaloacetate and pyruvate in the treatment of subarachnoid hemorrhage (SAH) in rats. Isotonic saline, 250 mg/kg oxaloacetate, or 125 mg/kg pyruvate was injected intravenously in 60 rats, 60 minutes after induction of SAH at a rate of 0.1 ml/100 g/min for 30 minutes. There were 20 additional rats that were used as a sham-operated group. Blood samples were collected at baseline and 90 minutes after SAH. Neurological performance was assessed at 24 h after SAH. In half of the rats, glutamate concentrations in the cerebrospinal fluid were measured 24 h after SAH. For the remaining half, the blood brain barrier permeability in the frontal and parieto-occipital lobes was measured 48 h after SAH. Blood glutamate levels were reduced in rats treated with oxaloacetate or pyruvate at 90 minutes after SAH (p

Several motor-function scales have been developed to assess neurological function in animal models of stroke, subarachnoid hemorrhage and closed head injury. We hypothesize that the location of arterial and venous catheters, even in the absence of brain injury, may impact rats' motor performance. Our study examined the effect of catheter location, rate of infection and the time required for catheter placement. We further describe an original technique of tail artery cannulation without exposure of the artery. Sixty-one rats were anesthetized and randomly assigned to one of seven groups, including no catheter, tail artery or artery + vein catheters, or femoral artery or artery + vein catheters. A neurological severity score (NSS) was determined at 1 h, 24 h and 48 h after surgical preparation or catheter placement. NSS at 1 h after placement of unilateral and bilateral femoral catheters was higher than the NSS observed at 1 h after placement of tail arterial and venous catheters (P < 0.01). The NSS also was higher at 24 h in the bilateral femoral catheter groups as compared with the tail catheter groups (P < 0.05). There were no differences in the NSS observed between the groups that had tail catheters and the sham group at 1 h, 24 h or 48 h. Infection rate at the site of catheter placement and the time required for catheter placement was also higher in the femoral catheter groups (P < 0.001). Thus, we propose that the line location may bias a study's results and lead to deceptive interpretations of neurological assessment following rat head injury. Compared to femoral vessels, tail blood vessels are preferable locations for lines placement.

To compare postoperative pain perception and analgesia requirements in patients undergoing cesarean section (CS) using general versus spinal anesthesia. A prospective, observational study of patients undergoing elective CS during 2009 under either general or spinal anesthesia. Postoperative pain intensity and analgesia requirements were evaluated for up to 48 h after surgery. A total of 153 women were enrolled; 77 received general and 76 received regional anesthesia. Postoperative meperidine requirements in the first 24 h were significantly higher in the general anesthesia group. Pain scores were mostly comparable between the groups. Nevertheless, lower pain scores were graded after 8 h in the general versus the spinal anesthesia and this reversed at 48 h. Spinal anesthesia is comparable to general anesthesia in terms of post-operative pain control. In choosing the type of anesthesia in CS, other factors such as the urgency and potential maternal and fetal hazards should be taken into account.

Isoflurane-anesthetized rats subjected to traumatic brain injury (TBI) show a transient reduction in blood L-glutamate levels. Having previously observed that isoproterenol produces a sustained decrease in blood glutamate levels in naive rats, we investigated the possible effects of nonselective and selective β1 and β2 adrenergic agonists and antagonists both on blood glutamate levels and on the neurological outcomes of rats subjected to TBI.Rats received either 10 mL/kg of isotonic saline 1 hour after TBI, 50 µg/kg of isoproterenol pretreatment 30 minutes before TBI, 10 mg/kg of propranolol pretreatment 60 minutes before TBI, 10 mg/kg of metoprolol pretreatment 60 minutes before TBI, or 10 mg/kg of butaxamine pretreatment 40 minutes before TBI and 10 minutes before pretreatment with 50 µg/kg isoproterenol or 10 mg/kg of propranolol 60 minutes after TBI. A neurological severity score (NSS) was measured at 1, 24, and 48 hours after TBI. Blood glutamate, blood glucose, mean arterial blood pressure, and heart rate were measured at the time of drug injection, at the time of TBI, 60 minutes after TBI, and 90 minutes after TBI.Blood glutamate levels decreased spontaneously by 60 minutes after TBI in the control group (P0.05), reverting to baseline levels by 90 minutes after TBI. A pretreatment with either 10 mg/kg of metoprolol 60 minutes before TBI or with 50 µg/kg of isoproterenol 30 minutes before TBI also reduced blood glutamate levels (P0.05) both at 90 minutes after TBI and improved the NSS measured 24 and 48 hours after TBI in comparison with the control saline-treated group. However, a 10-mg/kg butoxamine pretreatment 40 minutes before TBI and 10 minutes before pretreatment with 50 µg/kg of isoproterenol or 10 mg/kg of propranolol 60 minutes before TBI neither affected blood glutamate levels across time after TBI nor caused any significant change in the NSS measured 24 and 48 hours after TBI in comparison with the control saline-treated group. A strong correlation (r(2)=0.73) was demonstrated between the percent decrease in blood glutamate levels at 90 minutes after TBI and the percent improvement of NSS measured 24 hours after TBI.The results suggest that the transient blood glutamate reduction seen after TBI is the result of a stress response and of the activation of the sympathetic nervous system through the β2 adrenergic receptors, causing an increase of the brain-to-blood efflux of glutamate observed with excess brain glutamate levels after a brain insult. This strongly correlates with the neurological improvement observed 24 hours after TBI.

Objective: To evaluate the impact of local lidocaine incision-site injection in patients undergoing cesarean deliveries (CD), on post operative pain and analgesic requirements. Study design: In this prospective, double-blinded, placebo-controlled study, patients undergoing elective CD were randomly assigned to receive 1% lidocaine solution or placebo to the incision site, prior to the performance of a Pfannenstiel incision. Pain intensity was evaluated for up to 48 hours after surgery and analgesic requirements of the patients were recorded. Results: During the study period, 153 patients were enrolled; 77 received pre-emptive analgesia with lidocaine and 76 received a placebo. No significant differences were noted between the groups in respect to parity, previous CD, maternal age and gestational age. Pain scores or requirements of analgesia did not differ between the groups. Conclusion: Pre-emptive analgesia with local incision-site injection with lidocaine does not seem beneficial in reducing post cesare...

BACKGROUND Elevated levels of glutamate in brain fluids, in the context of several neurodegenerative conditions, are associated with a worsened neurological outcome. Because there is a clear relationship between brain glutamate levels and glutamate levels in the blood, and an association of the latter with stress, the purpose of this study was to investigate the effects of glucose, insulin, and glucagon on rat blood glutamate levels. METHODS Rats received either 1 mL/100 g of rat body weight (BW) intravenous isotonic saline (control), 150 mg/1 mL/100 g BW intravenous glucose, 75 mg/1 mL/100 g BW intravenous glutamate, 50 g/100 g BW intraparitoneal glucagon, or 0.2 UI/100 g BW intraparitoneal insulin. Blood samples were subsequently drawn at 0, 30, 60, 90, and 120 minutes for determination of blood glutamate and glucose levels. RESULTS We observed a significant decrease in blood glutamate levels at 30 minutes after injection of glucose (P

In previous studies, we have shown that by increasing the brain-to-blood glutamate efflux upon scavenging blood glutamate with either oxaloacetate or pyruvate, one achieves highly significant neuroprotection particularly in the context of traumatic brain injury. The current study examines, for the first time, how the blood glutamate scavenging properties of glutamate-pyruvate transaminase (GPT), alone or in combination with pyruvate, may contribute to the spectrum of its neuroprotective mechanisms and improve the outcome of rats exposed to brain ischemia, as they do after head trauma. Rats that were exposed to permanent middle cerebral artery occlusion (MCAO) and treated with intravenous 250 mg/kg pyruvate had a smaller volume of infarction and reduced brain edema, resulting in an improved neurological outcome and reduced mortality compared to control rats treated with saline. Intravenous pyruvate at the low dose of 31.3 mg/kg did not demonstrate any neuroprotection. However, when combined with 0.6 mg/kg of GPT there was a similar neuroprotection observed as seen with pyruvate at 250 mg/kg. Animals treated with 1.69 g/kg glutamate had a worse neurological outcome and a larger extent of brain edema. The decrease in mortality, infarcted brain volume and edema, as well as the improved neurological outcome following MCAO, was correlated with a decrease in blood glutamate levels. We therefore suggest that the blood glutamate scavenging activity of GPT and pyruvate contributes to the spectrum of their neuroprotective mechanisms and may serve as a new neuroprotective strategy for the treatment of ischemic stroke.

Middle cerebral artery occlusion (MCAO) is widely used as a rat model of focal brain ischemia. Evaluation of brain damage often includes the morphological analysis of the injury area, MRI, and various scales which depend on functional tests, commonly known as neurological severity score (NSS). We determined the optimal number of NSS tests and assessed their capacity for non-invasive evaluation of brain ischemic injury in the rat MCAO model. 275 male Sprague-Dawley rats were randomly divided into five groups, given either permanent (p) MCAO or transient (t) MCAO using an uncoated 4-0 monofilament catheter or a silicone-coated monofilament. The rats' neurological status was examined before and at 1 and 24h following MCAO. The size of brain injury was then measured histologically and the extent of right cerebral hemisphere edema was calculated. We established a correlation between these tests and morphological data for brain injury. Adjusted R(2) of the prediction of total histology score was 0.7. The Hosmer-Lemeshow p-value of this model was 0.812 for total brain histology. For the brain edema the adjusted R(2) of the prediction model was 0.48. The Hosmer-Lemeshow p-value of this model was 0.558 for brain edema. Our methods of estimating infarct size produces reliable and well correlated results at 24h and demonstrates to be an easy and quick way to assess infarct size soon after ischemic injury has occurred. The described method for neurological assessment could ultimately aid in assessing various treatment modalities in the early hours following stroke.

To investigate pregnancy outcome of patients following splenectomy.A retrospective study comparing pregnancies of women who have and have not undergone splenectomy was performed. The study investigated a select population representing the south of Israel. Women lacking antenatal care as well as those having multiple gestations were excluded from the analysis. Stratified analysis, using a multiple logistic regression model, was performed to control for confounders.During the study period, there were 219,656 deliveries, of which 150 occurred in women who underwent splenectomy. Postsplenectomy women tended to be older, were more likely to be Jewish, and had a lower number of deliveries and an earlier gestational age at delivery. Higher rates of fertility treatment, previous cesarean delivery, and severe preeclampsia were found among postsplenectomy women. In addition, splenectomy was significantly associated with pregnancy and labor complications, such as cesarean delivery, pneumonia during pregnancy, and complications of anesthesia and sedation during labor. Using a multivariate analysis with backward elimination, the following conditions were independently associated with splenectomy: previous cesarean delivery (odds ratio [OR] 1.5, 95% confidence interval [CI] 1.1-2.3, p=0.039), fertility treatment (OR 2.6, 95% CI 1.3-5.4, p=0.008), preterm delivery (OR 1.9, 95% CI 1.3-3.1, p=0.003), and maternal age (OR 1.04, 95% CI 1.015-1.07, p=0.002). After controlling for possible confounders by using another multivariate analysis with preterm delivery as the outcome variable, splenectomy was found to be an independent risk factor for preterm delivery (OR 2.1, 95% CI 1.4-3.3, p=0.001).Splenectomy is an independent risk factor for preterm delivery.

This study aimed at determining trends, risk factors and pregnancy outcome in women with uterine rupture. A population-based study, comparing all singleton deliveries with and without uterine rupture between 1988 and 2009 was conducted. Statistical analysis was performed using a multiple logistic regression analysis. Uterine rupture occurred in 0.06% (n = 138) of all deliveries included in the study (n = 240,189); 59% in women with a previous cesarean delivery (CD). A gradual increase in the rate of uterine rupture from 1988 (0.01%) to 2009 (0.05%) was noted. Independent risk factors for uterine rupture in a multivariable analysis were: previous CD (OR = 7.4, 95% CI 5.2–10.6), preterm delivery (

The purpose of the present study was to examine obstetric outcome of patients following conization and specifically the risk for preterm delivery (PTD).A population-based study was performed comparing pregnancies in women following conization with those who had not undergone the procedure. Stratified analysis, using a multiple logistic regression model was performed to control for confounders.Out of 104,670 deliveries, 53 women (0.05%) had undergone conization. Most conizations were performed using loop electrosurgical excision procedure (LEEP). Using multivariable analysis, the following conditions were significantly associated with conization: advanced maternal age, PTD before the 34th week, low birth weight, and cervical incompetence with cerclage. Higher rates of perinatal mortality were noted in pregnancies of women with conization, but after controlling for PTD, the association lost its significance. The risk of PTD34 weeks was significantly higher than the comparison group (OR 7.73 95% CI 3.77-15.85, p0.001). This association remained significant after controlling for confounders, such as cervical incompetence, smoking, maternal age, birth order and year of delivery (OR 2.8 95% CI 1.3-6.1, p = 0.008). When comparing pregnancy outcomes of women with and without cerclage due to cervical incompetence, no significant differences were documented.A clear association exists between conization and PTD before the 34th week. This association persists after controlling for variables considered to coexist with PTD. Careful surveillance is required in pregnancies of women following conization for early detection of preterm contractions and PTD.

This study examines the effects of the activation of β1 and β2-adrenergic receptors on glutamate homeostasis in the blood of naive rats. Forty five male Sprague–Dawley rats were randomly assigned into one of seven treatment groups that were treated with various β-adrenergic receptor agonist and antagonist drugs. Blood glutamate levels were determined at t = 0, 30, 60, 90, and 120 min. The activation of β1 and β2-adrenergic receptors via isoproterenol hydrochloride administration produced a marked sustained decrease in blood glutamate levels by 60 min after treatment (ANOVA, t = 60, 90 min: P < 0.05, t = 120 min: P < 0.01). Pretreatment with propranolol hydrochloride (a non-selective β-adrenergic receptor blocker) or butaxamine hydrochloride (a selective β2-adrenergic receptor blocker) occluded the isoproterenol-mediated decrease in blood glutamate levels. Propranolol alone had no effect on blood glutamate levels. Selective β1-adrenergic receptor blockade with metoprolol resulted in decreased blood glutamate levels (ANOVA, t = 90 min: P < 0.05, t = 120 min: P < 0.01). Butaxamine hydrochloride alone resulted in a delayed-onset increase in glutamate levels (ANOVA, t = 120 min: P < 0.05). The results suggest that the activation of β2 receptors plays an important role in the homeostasis of glutamate in rat blood.

A new modified two-dimensional quasi-gasdynamic model for traffic flows is studied. Both sufficient and necessary conditions are derived for the stability of space-harmonic perturbations with respect to a constant background in the linearized statement.

Isoflurane-anesthetized rats submitted to a closed head injury (CHI) display a significant decrease of their blood glutamate levels. Having demonstrated that a decrease of blood L-glutamate (glutamate) causes an increase of the driving force for a spontaneous brain-to-blood glutamate efflux, and consequently affords brain neuroprotection, we investigated here the possible mechanisms which can affect blood glutamate levels. Reasoning that the spontaneous decrease of blood glutamate levels post CHI could be part of a stress response, we observed that the stress involved in tail artery catheterization under isoflurane anesthesia does not affect blood glutamate levels. Investigating in naïve rats the stress effectors, we found that corticotropin-releasing factor (CRF) significantly decreased blood glutamate levels. Pretreatment with antalarmine (a selective type-1 CRF receptor antagonist) occludes the CRF-mediated decrease in blood glutamate levels. In contrast, the adrenocorticotrophic hormone (ACTH) did not affect blood glutamate levels. Investigating the effectors of the sympathetic/adrenomedullary system, we observed that in naïve rats, adrenaline but not noradrenaline decreased blood glutamate levels. Confirming the role of adrenaline, propranolol pretreatment (a non-selective beta-antagonist) prevented the spontaneous decrease of blood glutamate observed post CHI. On the strength of these results, we further observed that isoproterenol (a beta(1/2)-selective adrenoreceptor agonist) produced a marked sustained decrease in blood glutamate levels. These results suggest that stress induces a decrease of blood glutamate levels partly via the activation of peripheral CRF receptors and the activation of the beta-adrenoreceptors. We propose that this newly identified component of the stress response could be a peripherally mediated defense mechanism of the injured brain against the deleterious effects of excess glutamate.

We consider an initial-boundary value problem for the one-dimensional nonstationary Schrodinger equation on the half-axis and study a two-level symmetric finite-difference scheme of Numerov type with higher approximation order. This scheme is constructed on a finite mesh, which is uniform with respect to space, with a nonlocal approximate transparent boundary condition of a general form (of Dirichlet-to-Neumann type). We obtain assertions about the stability of the finite-difference scheme in two norms with respect to the initial data and free terms in the equation and in the approximate transparent boundary condition under suitable conditions in the form of inequalities on the operator of approximate transparent boundary condition. Bibliography: 12 titles.

To investigate pregnancy and labour outcomes in grand and great grand multiparous women.A retrospective population-based study was conducted between the years 1988 and 2007. Parturients were classified into three groups: multiparous; 2-5 deliveries, grand multiparous; 6-9 deliveries, and great grand multiparous; 10+ deliveries. Stratified analyses included multiple logistic regression models.A significant linear association was found between parity and adverse maternal and perinatal outcomes such as malpresentation, labour dystocia, caesarean delivery, postpartum haemorrhage, maternal anaemia (HB10), congenital malformations and perinatal mortality. Using multivariable logistic regression models, grand multiparity was found an independent risk factor for labour dystocia, first stage (OR=1.5, P0.001), and perinatal mortality (OR=2.0, P0.001). Great grand multiparity was found an independent risk factor for labour dystocia, first stage (OR=2.6, P0.001), labour dystocia, second stage (OR=2.1, P0.001), and perinatal mortality (OR=2.5, P0.001).Women with high birth order are at increased risk for adverse obstetric outcomes. The risk is higher for great grand multiparous women compared to grand multiparous women. Grand and great grand multiparity are independent risk factors for labour dystocia and perinatal mortality.

A recently proposed two-dimensional quasi-gasdynamic model of traffic flows is considered. Its Petrovskii parabolicity is analyzed, and the stability of small perturbations against a constant background is investigated. In a nonlinear setting, an energy equality is derived and an energy estimate of the solution is obtained.

An initial–boundary value problem for a generalized 2D Schrodinger equation in a rectangular domain is considered. Approximate solutions of the form c 1 ( x 1 , t ) χ 1 ( x 1 , x 2 ) + ⋯ + c N ( x 1 , t ) χ N ( x 1 , x 2 ) are treated, where χ 1 , … , χ N are the first N eigenfunctions of a 1D eigenvalue problem in x 2 depending parametrically on x 1 and c 1 , … , c N are coefficients to be defined; they are of interest for nuclear physics problems. The corresponding semidiscrete Galerkin approximate problem is stated and analyzed. Uniform-in-time error bounds of arbitrarily high orders O ( N − θ log N ) in L 2 and O ( N − ( θ − 1 ) log 1 / 2 N ) in H 1 , θ > 1 , are proved.

We consider a 1D Schrodinger equation with variable coefficients on the half-axis. We study a family of two-level symmetric finite-difference schemes with a three-point parameter dependent averaging in space. This family includes a number of particular schemes. The schemes are coupled to an approximate transparent boundary condition (TBC). We prove two stability bounds with respect to initial data and a free term in the main equation, under suitable conditions on an operator of the approximate TBC. We also consider the family of schemes on an infinite mesh in space. We derive and analyze the discrete TBC allowing to restrict these schemes to a finite mesh and prove the stability conditions for it. Numerical examples are also included.

We deal with the 1d shallow water system of equations and exploit its special parabolic regularization satisfying the energy balance law. We construct a three-point symmetric in space discretization such that the discrete energy balance law holds and check that it is well-balanced. The results of numerical experiments for the associated explicit finite-difference scheme are also given for several known tests to confirm its reliability and some advantages. The practical error behavior is also analyzed.

Initial-boundary value problems for self-adjoint parabolic equations on a semiaxis and a semibounded strip are considered. For finite-difference σ-schemes, an alternative method for stating approximate transparent boundary conditions is suggested and conditions ensuring unconditional stability in the energy norm with respect to the initial data and free terms for a weight σ ≥ 1/2 are presented. The validity of these stability conditions in the case of discrete transparent boundary conditions is proved (by several methods), and the derivation of the latter conditions is revisited.

Congenital insensitivity to pain with anhidrosis (CIPA) is a rare autosomal recessive disorder characterized by recurrent episodic fevers, anhidrosis, absent reaction to noxious stimuli, self-mutilating behavior, and mental retardation. The anesthetic management of patients with CIPA is challenging. Autonomic nervous system abnormalities are common, and patients are at increased risk for perioperative complications.In this study, we describe our experience with 35 patients with CIPA who underwent 358 procedures requiring general anesthesia between 1990 and 2013.During surgery, 3 patients developed hyperthermia intraoperatively (37.5°C) without prior fever. There were no cases of intraoperative hyperpyrexia (40°C). Aspiration was suspected in 2 patients, and in another patient aspiration was prevented by the use of endotracheal tube, early detection of regurgitation, and aggressive suctioning. One patient had cardiac arrest requiring cardiopulmonary resuscitation. Intraoperative bradycardia was observed in 10 cases, and postoperative bradycardia was observed in 11 cases.Regurgitation, hyperthermia, and aspiration were uncommon, but the incidence of bradycardia was higher than has been reported in previous studies. CIPA remains a challenge for anesthesiologists. Because of the rare nature of this disorder, the risk of various complications is difficult to predict.

Although emergency department visit forecasting can be of use for nurse staff planning, previous research has focused on models that lacked sufficient resolution and realistic error metrics for these predictions to be applied in practice. Using data from a 1100-bed specialized care hospital with 553,000 patients assigned to its healthcare area, forecasts with different prediction horizons, from 2 to 24 weeks ahead, with an 8-hour granularity, using support vector regression, M5P, and stratified average time-series models were generated with an open-source software package. As overstaffing and understaffing errors have different implications, error metrics and potential personnel monetary savings were calculated with a custom validation scheme, which simulated subsequent generation of predictions during a 4-year period. Results were then compared with a generalized estimating equation regression. Support vector regression and M5P models were found to be superior to the stratified average model with a 95% confidence interval. Our findings suggest that medium and severe understaffing situations could be reduced in more than an order of magnitude and average yearly savings of up to €683,500 could be achieved if dynamic nursing staff allocation was performed with support vector regression instead of the static staffing levels currently in use.

Pathologically elevated glutamate concentrations in the brain's extracellular fluid are associated with several acute and chronic brain insults. Studies have demonstrated that by decreasing the concentration of glutamate in the blood, thereby increasing the concentration gradient between the brain and the blood, the rate of brain-to-blood glutamate efflux can be increased. Blood glutamate scavengers, pyruvate and oxaloacetate have shown great promise in providing neuroprotection in many animal models of acute brain insults. However, glutamate scavengers' potential systemic toxicity, side effects and pharmacokinetic properties may limit their use in clinical practice. In contrast, extracorporeal methods of blood glutamate reduction, in which glutamate is filtered from the blood and eliminated, may be an advantageous adjunct in treating acute brain insults. Here, we review the current evidence for the glutamate-lowering effects of hemodialysis, peritoneal dialysis and hemofiltration. The evidence reviewed here highlights the need for clinical trials.

One-lung intubation (OLI) is among the most common complications of endotracheal intubation. None of the monitoring tools now available has proved effective for its early detection. In this study we investigated the efficacy of acoustic analysis for the detection of OLI. We collected lung sounds from 11 patients undergoing thoracic surgery requiring the placement of a double-lumen tube. Recordings of separate lung ventilation were performed after induction and confirmation of adequate tube positioning, before surgery. Samples of lung sounds were collected by three piezoelectric microphones, one on each side of the chest and one on the right forearm, for background noise sampling. The samples were filtered, the signals' energy envelopes were calculated, and segmentation to breath and rest periods was performed. Each respiration was classified into one of the three categories: bilateral ventilation, selective right-lung ventilation, or selective left-lung ventilation, on the basis of the ratio between the energy signals of each lung. OLI was accurately identified in 10 of the 11 patients during right OLI and in all 11 patients during left OLI. This study suggests that acoustic monitoring is effective for the detection of selective lung ventilation and may be useful for early diagnosis of OLI.

The classical Euler system of equations, which is mathematically a system of first-order quasilinear hyperbolic equations, describes inviscid gas flows. There are numerous modifications of the system, primarily including the viscous Navier‐Stokes equations, which are of the compound hyperbolic‐parabolic type. This paper addresses different modifications. First, we analyze a typical quasi-gasdynamic system of equations from [1]. It is shown that the system is parabolic in the sense of Petrovskii (in the physically most interesting range of parameters). Second, we consider the generalized Euler system of equations from [2]. It is established that the system is Petrovskii elliptic (which, in our view, makes its application problematic from the point of view of mechanics and computational mathematics). Third, two related modifications are examined, which are shown to be systems of secondorder quasilinear hyperbolic equations. Sketches of the proofs are presented. 1. The system of quasi-gasdynamic equations from

We consider the compressible Navier–Stokes system for 1D flows of a viscous heat-conducting gas. The zero velocity and stress together with the (positive) temperature or zero heat flux are prescribed on the boundaries. The large-time behavior of the solution is studied for the arbitrarily large initial data. Namely, the stabilization with the power rate of the specific volume divided by 1 + t and the temperature to constants as well as of the velocity to a linear function is proved in L2 and H1-norm by means of the Lyapunov functional method. The study is accomplished in the Lagrangian mass coordinates.

The stability of small perturbations against a constant background is studied for a system of quasi-gasdynamic equations in an arbitrary number of space variables. It is established that, for a fixed adiabatic exponent γ, the stability is determined only by the background Mach number, and a necessary and sufficient condition for stability at any Mach number is \(\gamma \leqslant \bar \gamma \), where \(\bar \gamma \approx 6.2479\). The proof is based on a direct analysis of the corresponding complex characteristic numbers depending on several parameters. The multidimensional case is successfully reduced to the one-dimensional one. Then, the generalized Routh-Hurwitz criterion is applied in conjunction with analytical calculations based on Mathematica.

We analyze the three-stage symmetrized locally 1D finite-difference scheme for solving an initial-boundary value problem for the 2D heat equation. Er- ror bounds of orders O � τ + |h| 2 � and O � τ 2 + |h| 2 � and related ones are proved for nonsmooth data. The sharpness in order of these in a strong sense is confirmed by deriving the corresponding lower error bounds. The error bounds are, in the main, worse than the known optimal error bounds that are valid, for example, for the sym- metric scheme. The above confirms the general conclusion that symmetrized locally 1D methods cannot serve as optimal methods for solving parabolic problems. 2000 Mathematics Subject Classification: 65M06; 65M15.

We consider global behaviour of viscous compressible flows with spherical symmetry driven by gravitation and an outer pressure, outside a hard core. For a general state function p = p ( ρ ) , we present global-in-time bounds for solutions with arbitrarily large data. For non-decreasing p , the ω -limit set for the density ρ is studied. For increasing p , uniqueness and static stability of the stationary solutions (including variational aspects) are investigated. Moreover, stabilization rate bounds toward the statically stable solutions are given and their nonlinear dynamical stability is shown.

We consider symmetric flows of a viscous compressible barotropic fluid with a free boundary, under a general mass force depending both on the Eulerian and Lagrangian co-ordinates, with arbitrarily large initial data. For a general non-monotone state function p, we prove uniform-in-time energy bound and the uniform bounds for the density ρ, together with the stabilization as t ∞ of the kinetic and potential energies. We also obtain H1-stabilization of the velocity v to zero provided that the second viscosity is zero. For either increasing or non-decreasing p, we study the Lλ-stabilization of ρ and the stabilization of the free boundary together with the corresponding ω-limit set in the general case of non-unique stationary solution possibly with zones of vacuum. In the case of increasing p and stationary densities ρS separated from zero, we establish the uniform-in-time H1-bounds and the uniform stabilization for ρ and v. All these results are stated and mainly proved in the Eulerian co-ordinates. They are supplemented with the corresponding stabilization results in the Lagrangian co-ordinates in the case of ρS separated from zero. Copyright © 2005 John Wiley & Sons, Ltd.

We study the Cauchy problem for the one-dimensional equations of a viscous heat-conducting gas in the Lagrangian mass coordinates with the initial data in the Lebesgue spaces. We prove the existence, the uniqueness and the Lipschitz continuous dependence on the initial data of global weak solutions. 1. Main theorems We study the existence, the uniqueness and the Lipschitz continuous dependence on initial data of global weak solutions to the Cauchy problem for the system of one-dimensional quasilinear equations of a viscous polytropic ideal gas in a strip QT := R × (0 ,T ), ηt = vx

1. An extensive literature is devoted to systems of quasilinear equations of motion of viscous compressible media (see [1, 2]). One of the problems of current interest is the development of the theory of global (with respect to time and data) weak solutions, including questions of their existence, uniqueness, and continuous dependence on data (such as initial data, the coefficients of the equations, the constant terms, etc.). For the system of equations of one-dimensional motion of a viscous heat-conducting gas, the last two questions were studied in [3–6] (see also [7, 8]). For more complicated systems of equations for reacting gases (in other words, in combustion problems) weak solutions were studied in [9, 10]. Quite recently, in [11], the existence of weak solutions was obtained for an even more complicated system of equations, namely, for a reacting binary gas mixture. Note that regular solutions of problems concerning binary mixtures were studied earlier in [12, 13]. The present paper is devoted to the questions of uniqueness of these weak solutions and of their continuous dependence on data. The system of quasilinear equations of one-dimensional motion of a viscous compressible reacting binary gas mixture is of the form

We consider the compressible 1D-Navier–Stokes system for a viscous heat-conducting gas, with a pressure law p(ρ,θ)=Rρθ+ a 3 θ 4 and a one-order kinetics to include radiative and reactive processes. The mass force and the ignition phenomenon are also taken into account. For large data and under general assumptions on the heat conductivity, we establish global in time bounds and exponential stabilization for solutions in Lq and H1-norms, by using new Lyapunov functionals. To cite this article: B. Ducomet, A. Zlotnik, C. R. Acad. Sci. Paris, Ser. I 338 (2004).

In the Eulerian coordinates we study 1D-flow of a viscous compressible barotropic fluid with an unknown free boundary for large initial data and mass force. Under fairly general conditions on the pressure function, viscosity coefficient, and a relation between the mass force and outer pressure we give the uniform with respect to time bounds for the solution and study its convergence to a stationary one as time tends to infinity. Moreover, in the case of uniquely defined stationary solution with strictly positive density we prove $L^{2}$ - and $H^{1}$ -stabilization rate estimates by constructing new Lyapunov functionals.

η(x, t) → η± ,v (x, t) → v± ,θ (x, t) → θ± as x →± ∞, 0

We consider an initial–boundary value problem for a system of quasilinear equations for one-dimensional flows of a viscous compressible barotropic fluid with large data. An outer pressure (possibly zero) is prescribed on one of the boundaries; also a self-gravitation is taken into account. The case of the stationary pressure with possible degeneration is studied. For a general non-monotone state function, either global estimates for the solution and its stabilization are proved or the growth of the fluid volume is bounded from below as t ∞. For the power state function, in addition, stabilization rate estimates (of the power type) are given. The study is accomplished in the Lagrangian mass co-ordinates. Copyright © 2003 John Wiley & Sons, Ltd.

SummaryThe present study aimed to determine different peripheral blood neutrophil functions in 18 morbidly obese subjects with body mass index (BMI) ranging between 35 and 69 kg/m2 in parallel with age- and gender-matched lean controls. Peripheral blood neutrophil functions of obese subjects and matched lean controls were determined. Neutrophils of obese subjects showed significant elevation of the release of basal superoxides (P < 0·0001), formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated superoxides (P < 0·0001) and opsonized zymosan (OZ)-stimulated superoxides (P < 0·045) compared with lean controls. Interestingly, there were no differences in phorbol myristate acetate (PMA)-stimulated superoxide production by neutrophils of the obese subjects and controls. There was also a significant elevation of chemotactic (P < 0·0003) and random (P < 0·0001) migration of neutrophils from obese subjects compared with lean controls. Phagocytosis, CD11b surface expression and adherence of neutrophils from obese subjects were not significantly different from those of the lean controls. The elevated superoxide production and chemotactic activity, together with the normal phagocytosis and adherence, suggest that neutrophils from obese subjects are primed and have the capability to combat infections. However, neutrophils in the priming state may participate in the pathogenesis of obesity-related diseases.

Optimal oxygen supply is the cornerstone of the management of critically ill patients after extubation, especially in patients at high risk for extubation failure. In recent years, high flow oxygen system devices have offered an appropriate alternative to standard oxygen therapy devices such as conventional face masks and nasal prongs.To assess the clinical effects of high flow nasal cannula (HFNC) compared with standard oxygen face masks in Intensive Care Unit (ICU) patients after extubation.We retrospectively analyzed 67 consecutive ventilated critical care patients in the ICU over a period of 1 year. The patients were allocated to two treatment groups: HFNC (34 patients, group 1) and non-rebreathing oxygen face mask (NRB) (33 patients, group 2). Vital respiratory and hemodynamic parameters were assessed prior to extubation and 6 hours after extubation. The primary clinical outcomes measured were improvement in oxygenation, ventilation-free days, re-intubation, ICU length of stay, and mortality.The two groups demonstrated similar hemodynamic patterns before and after extubation. The respiratory rate was slightly elevated in both groups after extubation with no differences observed between groups. There were no statistically significant clinical differences in PaCO2. However, the use of HFNC resulted in improved PaO2/FiO2 post-extubation (P0.05). There were more ventilator-free days in the HFNC group (P0.05) and fewer patients required reintubation (1 vs. 6). There were no differences in ICU length of stay or mortality.This study demonstrated better oxygenation for patients treated with HFNC compared with NRB after extubation. HFNC may be more effective than standard oxygen supply devices for oxygenation in the post-extubation period.

The Navier-Stokes equations of a compressible barotropic fluid in 1D with zero velocity boundary conditions are considered. We study the case of large initial data in H 1 as well as the mass force such that the stationary density is positive. The uniform lower bound for the density is proved. By constructing suitable Lyapunov functionals, decay rate estimates in L 2-norm and H 1-norm are given. The decay rate is exponential if so the decay rate of the nonstationary part of the mass force is. The results are proved in the Eulerian coordinates for a wide class of increasing state functions including $ p(\rho)=p_1\rho^\gamma $ with any γ > 0 as well as functions of arbitrarily fast growth. We also extend the results for equations of a multicomponent compressible barotropic mixture (in the absence of chemical reactions).

We consider the compressible barotropic Navier–Stokes system in one dimension, with a nonmonotone equation of state and self-gravitation. We solve an associated "fixed-free" boundary problem and prove asymptotic properties of the unique globally defined solution for large time. We also comment on a related model of quantum fluid describing the dynamics of nuclear matter with zero temperature and Coulomb effects.