Pharmacokinetics of rocuronium during the three stages of liver transplantation

BACKGROUND: Little is known about the influence of liver transplantation on the pharmacokinetics of most anesthetic drugs. The authors determined the pharmacokinetics of rocuronium during liver transplantation and examined whether variability in pharmacokinetics could explain variability in recovery of neuromuscular function. METHODS: Twenty patients undergoing liver transplantation were given rocuronium, 600 microg/kg, after induction of anesthesia and again after perfusion of the transplanted liver. Plasma was sampled to determine rocuronium concentrations. Pharmacokinetic models were fit to rocuronium concentrations versus time data using a mixed-effects population approach. Various models permitted changes in clearance (Cl) or central compartment volume to account for changes in hepatic function and circulatory status during the paleohepatic, anhepatic, and neohepatic periods. Time to initial recovery of four twitches of the orbicularis oculi was determined. RESULTS: During the paleohepatic and anhepatic periods, the typical value of Cl was 2.47 ml x kg(-1) x min(-1) and was not influenced by the magnitude of preexisting liver disease (as evidenced by prothrombin time, bilirubin, serum albumin, alanine transaminase [ALT], and aspartate transaminase [AST]). During the neohepatic period, the typical value of Cl varied as a function of the duration of warm ischemia of the hepatic allograft and was 2.72 ml x kg(-1) x min(-1) for a patient with an average 60-min period of warm ischemia; time to neuromuscular recovery varied as a function of Cl. CONCLUSIONS: Despite prolonged hypothermic ischemia, the newly transplanted liver eliminates rocuronium as well as the diseased native liver (and comparably with historical control values). However, some patients had decreased rocuronium Cl during the neohepatic period, apparently a result of prolonged graft warm ischemia. The authors' finding of preservation of hepatic drug elimination in the hepatic allograft is consistent with limited data for other drugs evaluated during anesthesia.     

The behavior of a crack near a low-angle grain boundary

This paper presents the results of a simplified analysis of the behavior of a microcrack in the vicinity of a low-angle grain boundary. Combining the well-known dislocation model of low angle grain boundaries developed by Burgers, Read and Shockley, and Cottrell (see e.g. [1]) with the crack/dislocation interaction solution developed by Atkinson [2] and Lo [3], a series expression is obtained for the stress intensity factors at the tip of a crack near such a boundary. The main purpose of the analysis is to introduce a grain boundary model which includes aspects of the physical microstructure at the boundary. Results are computed and discussed for a variety of geometrical configurations, with the intent of developing understanding of the role of such boundaries in fracture processes at the micro-level.

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Résumé Le rapport présente les résultats d'une analyse simplifiée du comportement d'une microfissure au voisinage d'une frontière de grain de faible inclinaison.En combinant le modèle bien connu développé par Burgers, Read et Shockleny, et Cottrell, pour décrire par dislocations une telle frontière de grain, avec la solution d'interaction des dislocations et d'une fissure développée par Atkinson et Lo, une expression en série est obtenue pour le facteur d'intensité de contrainte à l'extrémité d'une fissure située près de cette frontière.Le but essentiel de cette analyse est d'introduire un modèle de frontière de grain qui inclue les aspects de la microstructure physique de la frontière. On calcule les résultats pour une gamme de configurations géométriques, dans l'intention de développer une perception sur le rôle de telles frontières sur le processus de rupture à un niveau microscopique.

     

Racial factors and season of birth in schizophrenia: A reinterpretation of Gallagher, McFalls, and Jones.

B. J. Gallagher et al (see record 1984-06905-001) reported that Black and White schizophrenics differ in their seasonal birth patterns. The present authors argue that their conclusions are precluded by 4 methodological problems: inadequate sample sizes, an unusual White schizophrenic sample, biases in diagnosis, and unsatisfactory control groups. The present authors address these problems and examine the provisional implications of the Gallagher et al data for understanding the birth seasonality of schizophrenics. (5 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detection and identification of viruses by electron microscopy

Electron microscopy can aid in the rapid diagnosis of viral diseases, as it can be performed in a matter of hours, but on a routine basis it should be used in conjunction with other techniques. Initially, the specimen source and patient symptoms should be ascertained, as these will lend suggestions of possible agents while eliminating others; however, this information should not be allowed to prejudice observation in such a way as to cause oversight of an unlikely pathogen. Second, selection of the method of preparation should be based on sample consistency; extraction, debris clarification, concentration, tissue culture amplification, or embedment may be necessary. Finally, false-positive results must be avoided by differentiating viruses from cell organelles or debris, mycoplasmal or bacterial contamination, and bacteriophages.     

Effect of Microstructure on the Radioluminescence and Transparency of Ce-Doped Strontium Hafnate Ceramics

In this paper we report on the fabrication and characterization of SrHfO(3):Ce ceramics. Powders were prepared by solid-state synthesis using metal oxides and carbonates. X-ray diffraction measurements showed that phase-pure SrHfO(3) is formed at 1200°C. Inductively coupled plasma spectroscopy confirmed the purity and composition of each batch. SrHfO(3) exhibits several phase changes in the solid, but this does not appear to be detrimental to the ceramics. Microprobe experiments showed uniform elemental grain composition, whereas aluminum added as charge compensation for trivalent cerium congregated at grain boundaries and triple points. Radioluminescence spectra revealed that the light yield decreases when the concentration of excess Sr increases. The decrease in the light yield may be related to the change of Ce(3+) into Ce(4+) ions. For stoichiometric SrHfO(3):Ce, the light yield is about four times that of bismuth germanate (BGO), the conventional benchmark, indicating great potential for many scintillator applications.     

A longitudinal study of high scorers on the Hypomanic Personality Scale.

Former college students (n?=?36) identified by high scores on the Hypomanic Personality Scale (HYP; Eckblad & Chapman, 1986) were compared with control participants (n?=?31) at a 13-year follow-up assessment. As hypothesized, the HYP group reported more bipolar disorders and major depressive episodes than the control group. The HYP group also exceeded the control group on the severity of psychotic-like experiences, symptoms of borderline personality disorder, and rates of substance use disorders. HYP group members with elevated scores on the Impulsive–Nonconformity Scale (Chapman et al., 1984) experienced greater rates of bipolar mood disorders, poorer overall adjustment, and higher rates of arrest than the remaining HYP or control participants. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuropsychological differentiation of depression and anxiety.

The high comorbidity of depression and anxiety is well established empirically but not well understood conceptually, in terms of either psychological or biological mechanisms. A neuropsychological model of regional brain activity in emotion provides contrasting hypotheses for depression and anxiety, with depression associated with a relative decrease and anxiety with a relative increase in right-posterior activity. These hypotheses received support in a comparison of individuals diagnosed with depression and community controls, and also in a separate study of nonpatients administered a measure of perceptual asymmetry. Hierarchical regressions revealed that depression and anxiety were uniquely and jointly associated with perceptual asymmetry. In light of consistent empirical support for the model, implications for conceptualizations of the comorbidity of depression and anxiety are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)