Effects of the α₂-adrenergic agonist clonidine on the pharmacodynamics and pharmacokinetics of 3,4-methylenedioxymethamphetamine in healthy volunteers.

The mechanism of action of 3,4-methylenedioxymethamphetamine (MDMA; ecstasy) involves the carrier-mediated and potentially vesicular release of monoamines. We assessed the effects of the sympatholytic α₂-adrenergic receptor agonist clonidine (150 μg p.o.), which inhibits the neuronal vesicular release of norepinephrine, on the cardiovascular and psychotropic response to MDMA (125 mg p.o.) in 16 healthy subjects. The study used a randomized, double-blind, placebo-controlled crossover design with four experimental sessions. The administration of clonidine 1 h before MDMA reduced the MDMA-induced increases in plasma norepinephrine concentrations and blood pressure but only to the extent that clonidine lowered norepinephrine levels and blood pressure compared with placebo. Thus, no interaction was found between the cardiovascular effects of the two drugs. Clonidine did not affect the psychotropic effects or pharmacokinetics of MDMA. The lack of an interaction of the effects of clonidine and MDMA indicates that vesicular release of norepinephrine, which is inhibited by clonidine, does not critically contribute to the effects of MDMA in humans. Although clonidine may be used in the treatment of stimulant-induced hypertensive reactions, the present findings do not support a role for α₂-adrenergic receptor agonists in the prevention of psychostimulant dependence.

Fast subplasma membrane Ca2+ transients control exo-endocytosis of synaptic-like microvesicles in astrocytes

Astrocytes are the most abundant glial cell type in the brain. Although not apposite for long-range rapid electrical communication, astrocytes share with neurons the capacity of chemical signaling via Ca(2+)-dependent transmitter exocytosis. Despite this recent finding, little is known about the specific properties of regulated secretion and vesicle recycling in astrocytes. Important differences may exist with the neuronal exocytosis, starting from the fact that stimulus-secretion coupling in astrocytes is voltage independent, mediated by G-protein-coupled receptors and the release of Ca(2+) from internal stores. Elucidating the spatiotemporal properties of astrocytic exo-endocytosis is, therefore, of primary importance for understanding the mode of communication of these cells and their role in brain signaling. We here take advantage of fluorescent tools recently developed for studying recycling of glutamatergic vesicles at synapses (Voglmaier et al., 2006; Balaji and Ryan, 2007); we combine epifluorescence and total internal reflection fluorescence imaging to investigate with unprecedented temporal and spatial resolution, the stimulus-secretion coupling underlying exo-endocytosis of glutamatergic synaptic-like microvesicles (SLMVs) in astrocytes. Our main findings indicate that (1) exo-endocytosis in astrocytes proceeds with a time course on the millisecond time scale (tau(exocytosis) = 0.24 +/- 0.017 s; tau(endocytosis) = 0.26 +/- 0.03 s) and (2) exocytosis is controlled by local Ca(2+) microdomains. We identified submicrometer cytosolic compartments delimited by endoplasmic reticulum tubuli reaching beneath the plasma membrane and containing SLMVs at which fast (time-to-peak, approximately 50 ms) Ca(2+) events occurred in precise spatial-temporal correlation with exocytic fusion events. Overall, the above characteristics of transmitter exocytosis from astrocytes support a role of this process in fast synaptic modulation.

Mechanisms of eosinophil cytokine release

Human eosinophils have been demonstrated to contain a multitude of cytokines and chemokines that exist pre-formed within these cells. This content of pre-formed cytokines, with diverse potential biologic activities, provides eosinophils with capabilities distinct from most other leukocytes. The localization of pre-formed cytokines within eosinophils is both within specific granules and associated with substantial numbers of morphologically distinct cytoplasmic vesicles. Stimulation for release of specific cytokines, such as IL-4, leads to a regulated signal transduction cascade, which is dependent on the formation of leukotriene C4 within eosinophils where it acts as an intracrine mediator. IL-4 release occurs selectively and is by means of vesicular transport. The capabilities of eosinophils not only to rapidly release pre-formed cytokines but also to differentially regulate which cytokines are released endow eosinophils with distinct abilities in innate and acquired immunity.

The additive genetic variance after bottlenecks is affected by the number of loci involved in epistatic interactions.

We investigated the role of the number of loci coding for a neutral trait on the release of additive variance for this trait after population bottlenecks. Different bottleneck sizes and durations were tested for various matrices of genotypic values, with initial conditions covering the allele frequency space. We used three different types of matrices. First, we extended Cheverud and Routman's model by defining matrices of "pure" epistasis for three and four independent loci; second, we used genotypic values drawn randomly from uniform, normal, and exponential distributions; and third we used two models of simple metabolic pathways leading to physiological epistasis. For all these matrices of genotypic values except the dominant metabolic pathway, we find that, as the number of loci increases from two to three and four, an increase in the release of additive variance is occurring. The amount of additive variance released for a given set of genotypic values is a function of the inbreeding coefficient, independently of the size and duration of the bottleneck. The level of inbreeding necessary to achieve maximum release in additive variance increases with the number of loci. We find that additive-by-additive epistasis is the type of epistasis most easily converted into additive variance. For a wide range of models, our results show that epistasis, rather than dominance, plays a significant role in the increase of additive variance following bottlenecks.

Management of a post-operative multi-resistant infectious spondylitis associated with a kyphotic deformity.

Anterior spinal infection (prevertebral abscess and/or discitis) after posterior instrumentation for vertebral fractures is a challenging complication, since a new implant may become necessary anteriorly, in a septic environment. Generally accepted management guidelines are yet to be established. The authors present a case of posterior instrumentation for fractures of T12 and L1, complicated after 9 months with an anterior infection (prevertebral abscess and discitis) with extended-spectrum beta-lactamase (ESBL) producing Escherichia coli (E. coli). This case is unique in that the multi-resistant organism was isolated only after the second stage of infection treatment, which consisted of anterior débridement and anterior implantation of titanium cages and rods. In this particular case, infection was controlled despite implantation of multiple cages, screws and rods, and fusion was achieved, by means of intravenous antibiotic treatment for 12 months. At the latest follow-up, 24 months post surgery, there was no evidence of infection. This problem case may be helpful for surgeons confronted with spinal deformities secondary to infections with multi-resistant organisms.

The influence of cationic lipid type on in-vitro release kinetic profiles of antisense oligonucleotide from cationic nanoemulsions.

Novel formulations of cationic nanoemulsions based on three different lipids were developed to strengthen the attraction of the polyanionic oligonucleotide (ODN) macromolecules to the cationic moieties on the oil nanodroplets. These formulations were developed to prolong the release of the ODN from the nanoemulsion under appropriate physiological dilutions as encountered in the eye following topical application. Increasing the concentration of the new cationic lipid exhibiting two cationic amine groups (AOA) in the emulsion from 0.05% to 0.4% did not alter markedly the particle size or zeta potential value of the blank cationic nanoemulsion. The extent of ODN association did not vary significantly when the initial concentration of ODN remained constant at 10 microM irrespective of the cationic lipid nature. However, the zeta potential value dropped consistently with the low concentrations of 0.05% and 0.1% of AOA in the emulsions suggesting that an electrostatic attraction occurred between the cationic lipids and the polyanionic ODN molecules at the o/w interface. Only the nanoemulsion prepared with N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium salts (DOTAP) remained physically stable over time. DOTAP cationic lipid nanoemulsion was the most efficient formulation capable of retaining the ODN despite the high dilution of 1:100 with simulated tear solution (STS). Less than 10% of the ODN was exchanged in contrast to 40-50% with the other cationic nanoemulsions. The in-vitro release kinetic behavior of ODN exchange with physiological anions present in the STS appears to be complex and difficult to characterize using mathematical fitting model equations. Further pharmacokinetic studies are needed to verify our kinetic assumptions and confirm the in-vitro ODN release profile from DOTAP cationic nanoemulsions.

Involvement of microglia-neuron interactions in the tumor necrosis factor-alpha release, microglial activation, and neurodegeneration induced by trimethyltin.

Trimethyltin (TMT) is a neurotoxicant known to induce early microglial activation. The present study was undertaken to investigate the role played by these microglial cells in the TMT-induced neurotoxicity. The effects of TMT were investigated in monolayer cultures of isolated microglia or in neuron-enriched cultures and in neuron-microglia and astrocyte-microglia cocultures. The end points used were morphological criteria; evaluation of cell death and cell proliferation; and measurements of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and nitric oxide (NO) release in culture supernatant. The results showed that, in cultures of microglia, TMT (10(-6) M) caused, after a 5-day treatment, an increased release of TNF-alpha, without affecting microglial shape or cell viability. When microglia were cocultured with astrocytes, TNF-alpha release was decreased to undetectable levels. In contrast, in neuron-microglia cocultures, TNF-alpha levels were found to increase at lower concentrations of TMT (i.e., 10(-8) M). Moreover, at 10(-6) M of TMT, microglia displayed further morphological activation, as suggested by process retraction and by decrease in cell size. No morphological activation was observed in cultures of isolated microglial cells and in astrocyte-microglia cocultures. With regard to neurons, 10(-6) M of TMT induced about 30% of cell death, when applied to neuron-enriched cultures, whereas close to 100% of neuronal death was observed in neuron-microglia cocultures. In conclusion, whereas astrocytes may rather dampen the microglial activation by decreasing microglial TNF-alpha production, neuronal-microglial interactions lead to enhanced microglial activation. This microglial activation, in turn, exacerbates the neurotoxic effects of TMT. TNF-alpha may play a major role in such cell-cell communications.

Prospective phase II trial of extended treatment with rituximab in patients with B-cell post-transplant lymphoproliferative disease.

BACKGROUND AND OBJECTIVES The elective treatment of patients with post-transplant lymphoproliferative disorders is controversial. The purpose of this trial was to evaluate the efficacy of treatment with extended doses of rituximab adapted to the response in patients with post-transplant lymphoproliferative disorders after solid organ transplantation. DESIGN AND METHODS This was a prospective, multicenter, phase II trial. Patients were treated with reduction of immunosuppression and four weekly infusions of rituximab. Those patients who did not achieve complete remission (CR) received a second course of four rituximab infusions. The primary end-point of the study was the CR rate. RESULTS Thirty-eight patients were assesable. One episode of grade 4 neutropenia was the only severe adverse event observed. After the first course of rituximab, 13 (34.2%) patients achieved CR, 8 patients did not respond, and 17 patients achieved partial remission. Among those 17 patients, 12 could be treated with a second course of rituximab, and 10 (83.3%) achieved CR, yielding an intention-to-treat CR rate of 60.5%. Eight patients excluded from the trial because of absence of CR were treated with rituximab combined with chemotherapy, and six (75%) achieved CR. Event-free survival was 42% and overall survival was 47% at 27.5 months. Fourteen patients died, ten of progression of their post-transplant lymphoproliferative disorder. INTERPRETATION AND CONCLUSIONS These results confirm that extended treatment with rituximab can obtain a high rate of CR in patients with post-transplant lymphoproliferative disorders after solid organ transplantation without increasing toxicity, and should be recommended as initial therapy for these patients.

Enhanced antitumor activity of doxorubicin in breast cancer through the use of poly(butylcyanoacrylate) nanoparticles.

The use of doxorubicin (DOX), one of the most effective antitumor molecules in the treatment of metastatic breast cancer, is limited by its low tumor selectivity and its severe side effects. Colloidal carriers based on biodegradable poly(butylcyanoacrylate) nanoparticles (PBCA NPs) may enhance DOX antitumor activity against breast cancer cells, thus allowing a reduction of the effective dose required for antitumor activity and consequently the level of associated toxicity. DOX loading onto PBCA NPs was investigated in this work via both drug entrapment and surface adsorption. Cytotoxicity assays with DOX-loaded NPs were performed in vitro using breast tumor cell lines (MCF-7 human and E0771 mouse cancer cells), and in vivo evaluating antitumor activity in immunocompetent C57BL/6 mice. The entrapment method yielded greater drug loading values and a controlled drug release profile. Neither in vitro nor in vivo cytotoxicity was observed for blank NPs. The 50% inhibitory concentration (IC50) of DOX-loaded PBCA NPs was significantly lower for MCF-7 and E0771 cancer cells (4 and 15 times, respectively) compared with free DOX. Furthermore, DOX-loaded PBCA NPs produced a tumor growth inhibition that was 40% greater than that observed with free DOX, thus reducing DOX toxicity during treatment. These results suggest that DOX-loaded PBCA NPs have great potential for improving the efficacy of DOX therapy against advanced breast cancers.

Comparative Study of Chemoembolization, Loadable Beads: In vitro Drug Release and Physical Properties of DC Bead and Hepasphere, Loaded with Doxorubicin and Irinotecan

Purpose To characterize in vitro the loadability, physical properties, and release of irinotecan and doxorubicin from two commercially available embolization microspheres. Materials and Methods DC Bead (500-700 μm) and Hepasphere (400-600 μm) microspheres were loaded with either doxorubicin or irinotecan solutions. Drug amount was quantified with spectrophotometry, bead elasticity was measured under compression, and bead size and loading homogeneity were assessed with microscopy image analysis. Drug release was measured over 1-week periods in saline by using a pharmacopeia flow-through method. Results Almost complete drug loading was obtained for both microsphere types and drugs. Doxorubicin-loaded DC Beads maintained their spherical shape throughout the release. In contrast, Hepaspheres showed less homogeneous doxorubicin loading and, after release, some fractured microspheres. Incomplete doxorubicin release was observed in saline over 1 week (27% ± 2 for DC beads and 18% ± 7 for Hepaspheres; P = .013). About 75% of this amount was released within 2.2 hours for both beads. For irinotecan, complete release was obtained for both types of beads, in a sustained manner over 2-3 hours for DC Beads, and in a significantly faster manner as a 7-minute burst for Hepaspheres. Conclusions The two drug-eluting microspheres could be efficiently loaded with both drugs. Incomplete doxorubicin release was attributed to strong drug-bead ionic interactions. Weaker interactions were observed with irinotecan, which led to faster drug release.

Remote control of pulmonary blood flow: a dream comes true.

The indication for pulmonary artery banding is currently limited by several factors. Previous attempts have failed to produce adjustable pulmonary artery banding with reliable external regulation. An implantable, telemetrically controlled, battery-free device (FloWatch) developed by EndoArt SA, a medical company established in Lausanne, Switzerland, for externally adjustable pulmonary artery banding was evaluated on minipigs and proved to be effective for up to 6 months. The first human implant was performed on a girl with complete atrioventricular septal defect with unbalanced ventricles, large patent ductus arteriosus and pulmonary hypertension. At one month of age she underwent closure of the patent ductus arteriosus and FloWatch implantation around the pulmonary artery through conventional left thoracotomy. The surgical procedure was rapid and uneventful. During the entire postoperative period bedside adjustments (narrowing or release of pulmonary artery banding with echocardiographic assessment) were repeatedly required to maintain an adequate pressure gradient. The early clinical results demonstrated the clinical benefits of unlimited external telemetric adjustments. The next step will be a multi-centre clinical trial to confirm the early results and adapt therapeutic strategies to this promising technology.

Role of PPARβ in keratinocyte adhesion and migration during skin wound healing

RESUME L'homéostasie du tissu cutané est assurée par des interactions étroites entre les cellules le composant et par l'équilibre entre la différenciation et la prolifération des kératinocytes devant permettre un renouvellement constant du tissu. Après une blessure, les kératinocytes environnant la zone blessée sont activés par des cytokines. Ils acquièrent alors un phénotype migratoire qui s'accompagne d'une modulation de l'activité protéolytique de la matrice extra cellulaire, d'une modulation de la dynamique du cytosquelette d'active, de la polarisation de la cellule, de l'affaiblissement des contacts entre cellules et de changements dans leurs contacts avec la matrice extra cellulaire. PPARβ est un facteur de transcription activé par les acides gras et leurs dérivés. Il appartient à la famille des récepteurs nucléaires aux hormones et son expression est avérée dans les kératinocytes des follicules pileux et dans les kératinocytes inter-folliculaires activés par la blessure cutanée. Le rôle de PPARβ dans la peau est principalement lié à son effet protecteur contre l'apoptose ainsi qu'à son implication dans l'équilibre dynamique entre la prolifération et la différentiation des kératinocytes. L'objet de ce travail fut de déterminer le rôle de PPARβ dans les processus d'adhésion et de migration des kératinocytes activés durant la régénération de l'épithélium blessé. Nous avons montré que les souris dépourvues du gène codant pour PPARβ ont de sévères imperfections affectant la morphologie de l'épithélium. Ce phénotype est corrélé à la modulation imparfaite du réseau d'active chez les souris dépourvues de PPARβ, à un défaut de localisation de l'intégrine α3 impliquée dans les complexes induisant la migration cellulaire, ainsi qu'à la modulation de l'expression d'acteurs majeurs affectant l'activité protéolytique de la matrice extra cellulaire. En conclusion, nos résultats montrent que PPARβ est impliqué dans le contrôle de la dynamique du cytosquelette d'active et la polarisation des kératinocytes activés. PPARβ étant impliqué dans l'acquisition d'un phénotype migratoire, il est légitime de se demander s'il intervient de même dans d'autres types cellulaires, par exemple dans la transition épithéliale-mésenchymateuse durant le développement, ou encore la progression de cellules tumorales. SUMMARY Highly coordinated intercellular interactions and single cell metabolism ensure cell and tissue maintenance of the skin. Healing of a skin wound involves keratinocyte activation by cytokines and growth factors. Activated keratinocytes acquire a motile phenotype that requires extracellular matrix remodeling and subsequent ligand activation through proteolytic activity, as well as cytoskeletal reorganisation induced by the release of cell-cell junctions and by the signalling relayed via integrin receptors and their cytoplasmic adaptors. PPARβ is a transcription factor activated by polyunsaturated fatty acids and fatty acid derivatives which belong to the nuclear hormone receptor superfamily. It is expressed in activated keratinocytes where it plays an essential role in protecting them from apoptosis. In addition, it plays an important function in hair follicle morphogenesis at the time of elongation, via the regulation of the balance between keratinocyte differentiation and proliferation. The aim of the present work was to determine if PPARβ is also involved in the regulation of migration and adhesion properties of keratinocytes during skin wound healing. We have shown that wounded PPARβ null mice display severe abnormalities of the keratinocyte migratory layer as shown at the histological level and using three-dimensional reconstruction. This altered migratory phenotype is correlated to altered dynamic of the actin cytoskeleton network, impaired α3 integrin localisation in migrating keratinocytes and changes in the expression of a key actor involved in extracellular matrix proteolytic activity. These results show that PPARβ is implicated in the fine tuning of the actin network organisation and the polarisation of activated keratinocytes following an epithelial wound. Whether these mechanisms are also controlled by PPARβ in other cell types during epithelial mesenchymal transition or tumour cell progression is an interesting question to rise.

Regulation of catecholamine release and tyrosine hydroxylase in human adrenal chromaffin cells by interleukin-1beta: role of neuropeptide Y and nitric oxide.

Adrenal chromaffin cells synthesize and secrete catecholamines and neuropeptides that may regulate hormonal and paracrine signaling in stress and also during inflammation. The aim of our work was to study the role of the cytokine interleukin-1beta (IL-1beta) on catecholamine release and synthesis from primary cell cultures of human adrenal chromaffin cells. The effect of IL-1beta on neuropeptide Y (NPY) release and the intracellular pathways involved in catecholamine release evoked by IL-1beta and NPY were also investigated. We observed that IL-1beta increases the release of NPY, norepinephrine (NE), and epinephrine (EP) from human chromaffin cells. Moreover, the immunoneutralization of released NPY inhibits catecholamine release evoked by IL-1beta. Moreover, IL-1beta regulates catecholamine synthesis as the inhibition of tyrosine hydroxylase decreases IL-1beta-evoked catecholamine release and the cytokine induces tyrosine hydroxylase Ser40 phosphorylation. Moreover, IL-1beta induces catecholamine release by a mitogen-activated protein kinase (MAPK)-dependent mechanism, and by nitric oxide synthase activation. Furthermore, MAPK, protein kinase C (PKC), protein kinase A (PKA), and nitric oxide (NO) production are involved in catecholamine release evoked by NPY. Using human chromaffin cells, our data suggest that IL-1beta, NPY, and nitric oxide (NO) may contribute to a regulatory loop between the immune and the adrenal systems, and this is relevant in pathological conditions such as infection, trauma, stress, or in hypertension.

Dispersion of natural arsenic in the Malcantone watershed, Southern Switzerland: field evidence for repeated sorption-desorption and oxidation-reduction processes

In recent years, elevated arsenic concentrations have been found in waters and soils of many, countries, often resulting in a health threat for the local population. Switzerland is not an exception and this paper deals with the release and subsequent fate of arsenic in a 200-km(2) mountainous watershed, characterized by crystalline silicate rocks (gneisses, schists, amphibolites) that contain abundant As-bearing sulfide ore deposits, some of which have been mined for iron and gold in the past. Using analytical methods common for mineralogical, ground water and soil studies (XRD, XRF, XAS-XANES and -EXAFS, electron microprobe, extraction, ICP, AAS with hydride generator, ion chromatography), seven different field situations and related dispersion processes of natural arsenic have been studied: (1) release by rock weathering, (2) transport and deposition by water and ice; (3) release of As to the ground and surface water due to increasing pH; (4) accumulation in humic soil horizons; (5) remobilization by reduction in water-saturated soils and stagnant ground waters; (6) remobilization by using P-rich fertilizers or dung and (7) oxidation, precipitation and dilution in surface waters. Comparison of the results with experimental adsorption studies and speciation diagrams from the literature allows us to reconstruct and identify the typical behavior of arsenic in a natural environment under temperate climatic conditions. The main parameters identified are: (a) once liberated from the primary minerals, sorption processes on Fe-oxy-hydroxides dominate over Al-phases, such as Al-hydroxides or clay minerals and limit the As concentrations in the spring and well waters between 20 and 300 mug/l. (b) Precipitation as secondary minerals is limited to the weathering domain, where the As concentrations are still high and not yet too diluted by rain and soils waters. (c) Although neutral and alkaline pH conditions clearly increase the mobility of As, the main factor to mobilize As is a low redox potential (Eh close or below 0 mV), which favors the dissolution of the Fe-oxy-hydroxides on which the As is sorbed. (d) X-ray absorption spectroscopy (XAS) of As in water-logged humic forest soils indicates that the reduction to As III only occurs at the solid-water interface and that the solid contains As as As V (e) A and Bh horizons of humic cambisols can effectively capture As when As-rich waters flow through them. Complex spatial and temporal variation of the various parameters in a watershed results in repeated mobilization and immobilization of As, which continuously transports As from the upper to the lower part of a watershed and ultimately to the ocean. (C) 2004 Elsevier B.V. All rights reserved.

GPS analysis of human locomotion: further evidence for long-range correlations in stride-to-stride fluctuations of gait parameters.

During free walking, gait is automatically adjusted to provide optimal mechanical output and minimal energy expenditure; gait parameters, such as cadence, fluctuate from one stride to the next around average values. It was described that this fluctuation exhibited long-range correlations and fractal-like patterns. In addition, it was suggested that these long-range correlations disappeared if the participant followed the beep of metronome to regulate his or her pace. Until now, these fractal fluctuations were only observed for stride interval, because no technique existed to adequately analyze an extended time of free walking. The aim of the present study was to measure walking speed (WS), step frequency (SF) and step length (SL) with high accuracy (<1 cm) satellite positioning method (global positioning system or GPS) in order to detect long-range correlations in the stride-to-stride fluctuations. Eight participants walked 30 min under free and constrained (metronome) conditions. Under free walking conditions, DFA (detrended fluctuation analysis) and surrogate data tests showed that the fluctuation of WS, SL and SF exhibited a fractal pattern (i.e., scaling exponent alpha: 0.5 < alpha < 1) in a large majority of participants (7/8). Under constrained conditions (metronome), SF fluctuations became significantly anti-correlated (alpha < 0.5) in all participants. However, the scaling exponent of SL and WS was not modified. We conclude that, when the walking pace is controlled by an auditory signal, the feedback loop between the planned movement (at supraspinal level) and the sensory inputs induces a continual shifting of SF around the mean (persistent anti-correlation), but with no effect on the fluctuation dynamics of the other parameters (SL, WS).