Response to Comment on "Permanent human occupation of the central Tibetan Plateau in the early Holocene".

We show that Zhang and Li's sedimentological model for the Chusang travertine neglects the three-dimensional information from multiple outcrops and that their optically stimulated luminescence (OSL) age of about 20,000 years for the human imprints is untenable. We highlight the robustness of our chronology and explore reasons why Zhang and Li's OSL age is a gross overestimation of the real depositional age of the imprinted travertine.

Response to Comment on "Permanent human occupation of the central Tibetan Plateau in the early Holocene".

Zhang et al contest that Chusang was part of an annual mobility round that "more likely" included seasonal use of high-elevation environments than permanent use. We show that their probabilistic statement hinges on indefensible claims about hunter-gatherer mobility. In the context of quantitative data from hunter-gatherer ethnography, our travel model shows that seasonal-use models are highly unlikely to explain Chusang.

Permanent human occupation of the central Tibetan Plateau in the early Holocene.

Current models of the peopling of the higher-elevation zones of the Tibetan Plateau postulate that permanent occupation could only have been facilitated by an agricultural lifeway at ~3.6 thousand calibrated carbon-14 years before present. Here we report a reanalysis of the chronology of the Chusang site, located on the central Tibetan Plateau at an elevation of ~4270 meters above sea level. The minimum age of the site is fixed at ~7.4 thousand years (thorium-230/uranium dating), with a maximum age between ~8.20 and 12.67 thousand calibrated carbon-14 years before present (carbon-14 assays). Travel cost modeling and archaeological data suggest that the site was part of an annual, permanent, preagricultural occupation of the central plateau. These findings challenge current models of the occupation of the Tibetan Plateau.

RORγt expression in Tregs promotes systemic lupus erythematosus via IL-17 secretion, alteration of Treg phenotype and suppression of Th2 responses.

Systemic lupus erythematosus (SLE) is a common autoimmune disorder with a complex and poorly understood immunopathogenesis. However, a pathogenic role for the T helper type 17 (Th17) axis was demonstrated by many studies, while regulatory T cells (Tregs ) were shown to mediate protection. Recently, we and others characterized a novel and independent T cell population expressing both the Treg characteristic transcription factor forkhead box protein 3 (FoxP3) and the Th17-defining retinoic acid receptor-related orphan nuclear receptor γt (RORγt). Studies in a model of acute glomerulonephritis unveiled potent regulatory, but also proinflammatory, functions of RORγt+ FoxP3+ Tregs . This bi-functional nature prompted us to suggest the name 'biTregs '. Importantly, the pathogenic biTreg effects were dependent upon expression of RORγt. We thus aimed to evaluate the contribution of RORγt+ FoxP3+ biTregs to pristane-induced SLE and explored the therapeutic potential of interference with RORγt activation. Our analyses revealed expansion of IL-17 producing biTregs in a distinctive time-course and organ-specific pattern, coincident with the development of autoimmunity and tissue injury. Importantly, specific ablation of RORγt activation in endogenous biTregs resulted in significant amelioration of pristane-induced pulmonary vasculitis and lupus nephritis. As potential mechanisms underlying the observed protection, we found that secretion of IL-17 by biTregs was abrogated completely in FoxP3Cre  × RORCfl/fl mice. Furthermore, Tregs showed a more activated phenotype after cell-specific inactivation of RORγt signalling. Finally, and remarkably, biTregs were found to potently suppress anti-inflammatory Th2 immunity in a RORγt-dependent manner. Our study thus identifies biTregs as novel players in SLE and advocates RORγt-directed interventions as promising therapeutic strategies.

Genetic structure of populations of Rhizoctonia solani anastomosis group-1 IA from soybean in Brazil.

The Basidiomycete fungus Rhizoctonia solani anastomosis group (AG)-1 IA is a major pathogen of soybean in Brazil, where the average yield losses have reached 30 to 60% in some states in Northern Brazil. No information is currently available concerning levels of genetic diversity and population structure for this pathogen in Brazil. A total of 232 isolates of R. solani AG1 IA were collected from five soybean fields in the most important soybean production areas in central-western, northern, and northeastern Brazil. These isolates were genotyped using 10 microsatellite loci. Most of the multilocus genotypes (MLGTs) were site-specific, with few MLGTs shared among populations. Significant population subdivision was evident. High levels of admixture were observed for populations from Mato Grosso and Tocantins. After removing admixed genotypes, three out of five field populations (Maranhao, Mato Grosso, and Tocantins), were in Hardy-Weinberg (HW) equilibrium, consistent with sexual recombination. HW and gametic disequilibrium were found for the remaining soybean-infecting populations. The findings of low genotypic diversity, departures from HW equilibrium, gametic disequilibrium, and high degree of population subdivision in these R. solani AG-1 IA populations from Brazil are consistent with predominantly asexual reproduction, short-distance dispersal of vegetative propagules (mycelium or sclerotia), and limited long-distance dispersal, possibly via contaminated seed. None of the soybean-infecting populations showed a reduction in population size (bottleneck effect). We detected asymmetric historical migration among the soybean-infecting populations, which could explain the observed levels of subdivision.

Influence of lipid saturation grade and headgroup charge: a refined lung surfactant adsorption model.

Rapid adsorption of surfactant material to the air/liquid interface of the lung is essential for maintaining normal lung function. The detailed mechanism of this process, however, remains unclear. In this study, we elucidate the influence of lipid saturation grade and headgroup charge of surface layer lipids on surfactant protein (SP)-induced vesicle insertion into monolayers spread at the air/water interface of a film balance. We used dipalmitoylphosphatidlycholine (DPPC),1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) as monolayer lipids doped with either hydrophobic surfactant-specific protein SP-B or SP-C (0.2 and 0.4 mol %, respectively). Vesicles consisting of DPPC/DPPG (4:1, mol ratio) were injected into a stirred subphase to quantify adsorption kinetics. Based on kinetic film balance and fluorescence measurements, a refined model describing distinct steps of vesicle adsorption to surfactant monolayers is presented. First, in a protein-independent step, lipids from vesicles bridged to the interfacial film by Ca(2+) ions are inserted into defects of a disordered monolayer at low surface pressures. Second, in a SP-facilitated step, active material insertion involving an SP-B- or SP-C-induced flip-flop of lipids occurs at higher surface pressures. Negatively charged lipids obviously influence the threshold pressures at which this second protein-mediated adsorption mechanism takes place.

Solubility versus electrostatics: what determines lipid/protein interaction in lung surfactant.

Mammalian lung surfactant is a complex lipid/protein mixture covering the alveolar interface and has the crucial function of reducing the surface tension at this boundary to minimal values. Surfactant protein SP-B plays an important role for this purpose and was the focus of many recent studies. However, the specificity of lipid/SP-B interactions is controversial. Since these investigations were accomplished at varying pH conditions (pH 5.5 and 7.0), we studied the specificity of these interactions in a dipalmitoylphosphatidylcholine (DPPC)/dipalmitoylphosphatidylglycerol (DPPG)/SP-B (4:1:0.2 mol %) model system at either pH. Mainly fluorescence microscopy and laterally resolved time-of-flight secondary ion mass spectrometry were used to reveal information about the phase behavior of the lipids and the molecular distribution of SP-B in the lipid mixture. DPPG forms separated condensed domains due to a strong hydrogen-bond network, from which the protein is mainly excluded. Considering the protein as an impurity of the lipid mixture leads to the principle of the zone melting process: an impurity is highly more soluble in a liquid phase than in a solid phase. The phase behavior effect of the lipids mainly outperforms the electrostatic interactions between DPPG and SP-B, leading to a more passively achieved colocalization of DPPC and SP-B.

Phospholipase A2 inhibitors as potential anti-inflammatory agents.

Phospholipase A(2) (PLA(2))-catalyzed hydrolysis of membrane phospholipids results in the stoichiometric production of a free fatty acid, most importantly arachidonic acid, and a lysophospholipid. Both of these phospholipid metabolites serve as precursors for inflammatory mediators such as eicosanoids or platelet-activating factor (PAF). Since it was initially discovered that non-steroidal anti-inflammatory drugs inhibit prostaglandin synthesis, a vast amount of drug development has been performed to selectively inhibit the production of the inflammatory metabolites of arachidonic acid while preserving their protective role. This research has culminated in the development of selective cyclooxygenase-2 (COX-2) inhibitors that act on the inducible, inflammatory COX enzyme, but do not affect the constitutive prostaglandin synthesis in cells that is mediated via COX-1. The development of PLA(2) inhibitors as potential anti-inflammatory agents has also been extensively pursued since the release of arachidonic acid from membrane phospholipids by PLA(3) is one of the rate-limiting factors for eicosanoid production. In addition to the production of eicosanoids, PLA(2)-catalyzed membrane phospholipid hydrolysis is also the initiating step in the generation of PAF, a potent inflammatory agent. Thus, inhibition of PLA(2) activity should, in theory, be a more effective anti-inflammatory approach. However, developing an inhibitor that would be selective for the production of inflammatory metabolites and not inhibit the beneficial properties of PLA(2) has so far proved to be elusive. This review will focus on agents used currently to inhibit PLA(2) activity and will explore their possible therapeutic use.

[Analgesic dosage with (S)-ketamine/propofol vs. (S)-ketamine/midazolam: sedation, stress response and hemodynamics--a controlled study of surgical intensive care patients]. / Analgosedierung mit (S)-Ketamin/Propofol vs. (S)-Ketamin/Midazolam: Steuerbarkeit, Stressreaktion und Hämodynamik--Eine kontrollierte Anwendungsbeobachtung bei operativen Intensivpatienten.

OBJECTIVE: The study was undertaken to investigate the influence of two different regimens of analgosedation on control and quality of sedation, stress response and haemodynamic parameters. METHODS: After ethical approval, 30 surgical intensive care patients were investigated in an open, controlled design. Patients with initial cardiocirculatory stability received 0.33-1.0 mg/kg BW/h (S)-ketamine together with 1-3 mg/kg BW/h propofol (SK/P-group), whereas patients with impaired cardiocirculatory stability received 0.33-1.0 mg/kg BW/h (S)-ketamine and 0.033-0.1 mg/kg BW/h midazolam (SK/M-group). Analgosedation was titrated until tolerance of respirator treatment was achieved and the patient was asleep, but able to respond to simple commands. At least 12 h after beginning of analgosedation, a simple neurological examination ("diagnostic window") was undertaken. RESULTS: In both groups, biometric data and diseases were altogether comparable, and tolerance of respirator treatment was excellent. About 16 h after start of analgosedation, 13 of 14 patients (93%) in the SK/P-group were immediately cooperative. In 2 of 16 patients of the SK/M-group, self extubation occurred, and 9 of 14 remaining patients (64%) were immediately cooperative (p = 0.065). Assessment of control and quality of analgosedation indicated slight advantages in SK/P-patients. SEF90 showed predominant beta-activity in both collectives, which increased in the course of time. Adrenaline, noradrenaline, ADH, ACTH and cortisol were measured at 7 time points. All endocrine stress parameters were consistently above normal range, but decreased during the observation period (p < 0.05). In the SK/M-group, ADH was significantly and noradrenaline initially higher than in controls. Systolic arterial pressure was comparable, whereas heart rate was significantly lower in the SK/P-group (p = 0.001). No relevant changes of endocrine or haemodynamic parameters were observed at neurological examination. CONCLUSION: In surgical intensive care patients, analgosedation with SK/P showed some advantages over SK/M with respect to control and quality. The endocrine stress response was reduced by both regimens in course of time. Altogether higher levels of ADH and noradrenaline during SK/M-analgosedation let expect higher cardiocirculatory stability and possible reduction of catecholamine demand. Due to ketamine-typical beta-activity, a reliable assessment of sedation by the pEEG is not possible.

Variability in the bioavailability of phenytoin capsules in males and females.

PURPOSE: To determine inter-lot and intra-subject variability in the bioavailability of the 100 mg extended phenytoin sodium capsules. In addition, to determine the effect of gender and menstrual cycle on phenytoin bioavailability. METHODS: Three different lots of extended phenytoin sodium capsules were given to 12 healthy male and 12 healthy female subjects in a crossover fashion. One of the lots was also given a second time to each subject. Plasma phenytoin was determined, using an HPLC assay, in samples collected over a 73-hr period after each dose. RESULTS: The mean Cmax for the four administrations ranged from 1.71-1.79 microg/ml and mean AUC(0-infinity) values from ranged 53.0-54.1 microg*hr/ml. The elimination half-life was 3 hr shorter, and the AUC(0-infinity) adjusted for the mg/kg dose was 30% lower for females. Average bioequivalence was demonstrated between the three lots for both Cmax and AUC(0-infinity) based on the BE limit of 80-125%. Further, all confidence intervals of AUC(0-infinity) fell within the limit of 90-111%. There were no differences in the confidence limits for Cmax and AUC(0-infinity) determined separately for males and females. Also, there was no difference in the mean Cmax or AUC(0-infinity) for females when analyzed as a function of the week of their menstrual cycle. Individual bioequivalence was demonstrated between three lots of phenytoin using the constant-scaled method, but not the reference-scaled method. CONCLUSIONS: There was very little difference in the bioavailability of the three lots of phenytoin. Females exhibited a lower AUC(0-infinity) than males after adjustment of dose for body weight, but their inclusion in the study did not affect the assessment of bioequivalence. When dose was not adjusted for body weight, no difference in AUC(0-infinity) was seen between males and females.

United States Food and Drug Administration requirements for approval of generic drug products.

As generic products become more available for the treatment of psychiatric disorders, clinicians must stay abreast of the U.S. Food and Drug Administration (FDA) requirements for the approval of generic drug products. The FDA declares that pharmaceutical equivalents only are therapeutically equivalent, and pharmacokinetic data are all that is usually required to determine therapeutic equivalence. The rationale behind the overall concept of bioequivalence is that if 2 pharmaceutical equivalents provide identical plasma concentration-time profiles in humans, there is no evidence to demonstrate that the 2 identical dosage forms will exhibit a difference in safety and efficacy. This article reviews current terminology used in abbreviated new drug applications for generic products, typical bioequivalence study designs, and FDA bioequivalence guidance for clozapine.

Carbamazepine level-A in vivo-in vitro correlation (IVIVC): a scaled convolution based predictive approach.

A method is presented for prediction of the systemic drug concentration profile from in vitro release/dissolution data for a drug formulation. The method is demonstrated using four different tablet formulations containing 200 mg carbamazepine (CZM), each administered in a four way cross-over manner to 20 human subjects, with 15 blood samples drawn to determine the resulting concentration profile. Amount versus time dissolution data were obtained by a 75 rpm paddle method for each formulation. Differentiation, with respect to time, of a monotonic quadratic spline fitted to the dissolution data provided the dissolution rate curve. The dissolution curve was through time and magnitude scaling mapped into a drug concentration curve via a convolution by a single exponential, and the estimated unit impulse response function. The method was tested by cross-validation, where the in vivo concentration profiles for each formulation were predicted based on correlation parameters determined from in vivo-in vitro data from the remaining three formulations. The mean prediction error (MPE), defined as the mean value of 100% x(observed-predicted)/observed was calculated for all 240 cross-validation predictions. The mean values of MPE were in the range of 10-36% (average 22%) with standard deviations (S.D.s) in the range of 9-33% (average 13%), indicating a good prediction performance of the proposed in vivo-in vitro correlation (IVIVC) method.

The effect of gelatin cross-linking on the bioequivalence of hard and soft gelatin acetaminophen capsules.

PURPOSE: To determine if changes in the in vitro dissolution of hard and soft gelatin acetaminophen capsules, which result from gelatin crosslinking, are predictive of changes in the bioavailability of the capsules in humans. METHODS: Both hard and soft gelatin capsules were "stressed" by a controlled exposure to formaldehyde, resulting in unstressed, moderately stressed and highly stressed capsules. In vitro dissolution studies were conducted using water or SGF with and without pepsin as the media. Separate 24-subject, 3-way crossover human bioequivalence studies were performed on the unstressed and stressed acetaminophen capsules. Plasma acetaminophen was determined by high performance liquid chromatography (HPLC) for 12 hr after each dose. RESULTS: The in vitro rate of dissolution of hard and soft gelatin capsules was decreased by crosslinking. The bioequivalence studies showed that both hard and soft gelatin capsules, which failed to meet the USP dissolution specification in water, but complied when tested in SGF containing pepsin, were bioequivalent to the unstressed control capsules. The capsules that were cross-linked to the greatest extent were not bioequivalent to the unstressed control capsules, based on Cmax. A trend toward an increase in Cmax with increased level of cross-linking was observed, but this was only significant for the severely stressed capsules. CONCLUSIONS: On the basis of this study a two-tier in vitro dissolution test was developed using enzymes to distinguish between bioequivalent and bioinequivalent gelatin capsules.

Bioequivalence of methylphenidate immediate-release tablets using a replicated study design to characterize intrasubject variability.

PURPOSE: To determine the relative bioavailability of two marketed, immediate-release methylphenidate tablets. The study used a replicated study design to characterize intrasubject variability, and determine bioequivalence using both average and individual bioequivalence criteria. METHODS: A replicated crossover design was employed using 20 subjects. Each subject received a single 20 mg dose of the reference tablet on two occasions and two doses of the test tablet on two occasions. Blood samples were obtained for 10 hr after dosing, and plasma was assayed for methylphenidate by GC/MS. RESULTS: The test product was more rapidly dissolved in vitro and more rapidly absorbed in vivo than the reference product. The mean Cmax and AUC(0-infinity) differed by 11% and 9%, respectively. Using an average bioequivalence criterion, the 90% confidence limits for the Ln-transformed Cmax and AUC(0-infinity), comparing the two replicates of the test to the reference product, fell within the acceptable range of 80-125%. Using an individual bioequivalence criterion the test product failed to demonstrate equivalence in Cmax to the reference product. CONCLUSIONS: The test and reference tablets were bioequivalent using an average bioequivalence criterion. The intrasubject variability of the generic product was greater and the subject-by-formulation interaction variance was borderline high. For these reasons, the test tablets were not individually bioequivalent to the reference tablets.

Utilization-focused evaluation: evaluating the effectiveness of a hospital nursing orientation program.

Providing comprehensive orientation programs that prepare nurses for their role as staff nurses is an integral aspect of retention. Therefore, it is vital that staff development educators assess the effectiveness of their nursing orientation programs. In this article, the authors employ a utilization-focused evaluation format to assess a nursing orientation program and, based on the results, offer recommendations for strengthening such programs.

Xenon inhalation increases airway pressure in ventilated patients.

BACKGROUND: The inert gas xenon, known as an anaesthetic for nearly 50 years, is also used as a contrast agent during computerised tomography (CT)-scanning. As xenon has a higher density and viscosity than air, xenon inhalation may increase airway resistance. METHODS: In a retrospective study we investigated the effects of 33% xenon/67% oxygen on airway pressure and cardio-respiratory parameters in 37 long-term mechanically ventilated patients undergoing cerebral blood flow (rCBF) measurements by means of stable xenon-enhanced CT. RESULTS: Xenon administration caused a significant increase in peak airway pressure from 31.6+/-8.0 cm H2O to 42.7+/-16.9 cm H2O. This effect was reproducible, did not occur after reduction of inspiratory flow rate by 50% from 0.56+/-0.15 L x s(-1) to 0.28+/-0.08 L x s(-1), and vanished immediately after termination of xenon delivery. CONCLUSION: Due to the higher density and viscosity of this gas mixture, ventilation with xenon/oxygen produces a higher Reynolds' number than oxygen/air when given at the same flow rate. This means that during xenon ventilation the zone of transition from turbulent to laminar gas flow may be located more peripherally (in smaller airways) than during oxygen/air ventilation with a subsequent increase in airway resistance. Our results indicate that xenon inhalation may cause a clinically relevant increase of peak airway pressure in mechanically ventilated patients.

Risperidone treatment for juvenile bipolar disorder: a retrospective chart review.

OBJECTIVE: To investigate the effectiveness and tolerability of the atypical neuroleptic risperidone in the treatment of juvenile mania. METHOD: This is a retrospective chart review of outpatients with the diagnosis of bipolar disorder (DSM-IV) treated with risperidone at a university center. Response to treatment was evaluated using the Clinical Global Impression Scale (CGI) with separate assessments of mania, psychosis, aggression, and attention-deficit/hyperactivity disorder (ADHD). RESULTS: Twenty-eight youths (mean +/- SD age, 10.4 +/- 3.8 years) with bipolar disorder (25 mixed and 3 hypomanic) who had been treated with risperidone were identified. These children received a mean dose of 1.7 +/- 1.3 mg over an average period of 6.1 +/- 8.5 months. Using a CGI Improvement score of < or = 2 (very much/much improved) to define robust improvement, 82% showed improvement in both their manic and aggressive symptoms, 69% in psychotic symptoms, but only 8% in ADHD symptoms. CONCLUSIONS: Although limited by its retrospective nature, this study suggests that risperidone may be effective in the treatment of manic young people and indicates the need for controlled clinical trials of risperidone and other atypical neuroleptics in juvenile mania.

Absence of effect of stimulants on the phamacokinetics of desipramine in children.

We conducted a retrospective chart review to examine the pharmacokinetic interaction between desipramine and the stimulants methylphenidate and dexedrine using routinely monitored desipramine serum concentrations in children receiving desipramine either alone or with a stimulant. Subjects were 142 children and adolescents (age 6-17 yrs; 113 taking desipramine, 29 taking desipramine-stimulants) in whom 401 dose- and weight-normalized serum concentrations were evaluated (333 desipramine, 68 desipramine-stimulants). Desipramine pharmacokinetic parameters were similar for both groups, including mean weight-corrected dose (3.66+/-1.36 mg/kg, desipramine; 3.66+/-1.09 mg/kg, desipramine-stimulants; p=0.97), weight- and dose-normalized serum concentrations (47.26+/-39.26 [microg/L]/[mg/kg], desipramine, 39.02+/-19.92 [microg/L]/[mg/kg], desipramine-stimulants; p=0.09), and clearance (0.690+/-0.913 [L/kg]/hr, desipramine; 0.613+/-0.514 [L/kg]/hr, desipramine-stimulants; p=0.499). When stratified by age, gender, and type of stimulant, no difference was detected (p>0.05) between groups. Our findings indicate the absence of a clinically significant interaction between desipramine and stimulants.