in-vitro-method-to-control-concentrations-halogenated-gases-cultured

<em>In Vitro</em> Method to Control Concentrations of Halogenated Gases in Cultured Alveolar Epithelial Cells

Acute respiratory distress syndrome (ARDS) is a syndrome of diffuse alveolar injury with impaired alveolar fluid clearance and severe inflammation. The ...

CHU Clermont-Ferrand

A rapid, sensitive, and ready-to-use gas chromatography-mass spectrometry method for meprobamate assay using carisoprodol as internal standard is described. The method involves extracting a 0.2-mL sample with chloroform, previously acidified with HCl 0.2N. For the quantitative analysis, we used selected-ion monitoring mode, selecting the ion m/z 144 for quantification of meprobamate and m/z 245 for carisoprodol. Excellent linearity was found between 0 and 200 mg/L plasma. The limit of detection was 0.58 mg/L, and the limit of quantification was 1.93 mg/L. A high reproducibility [intra-assay coefficient of variation (CV) range of 2.3-4.3% and interassay CV range of 5.5-12.3%] and accuracy (intra-assay range of 96.8-112.3% and interassay range of 85.5-99.3%) were observed. Recoveries were concentration-independent (87.0%, 76.2%, and 81.2% for 20, 75 and 150 mg/L, respectively). No interference from endogenous compounds, other metabolites of meprobamate, or frequently coadministered drugs was detected. This sensitive, simple assay for meprobamate in plasma, whole blood, and urine meets the current requirements for bioanalytical assays in overdose cases.

A one-step and sensitive GC-MS assay for meprobamate determination in emergency situations.

The combined use of an automatic solid-phase extraction (SPE) apparatus with Oasis MCX cartridges and gas chromatography/mass spectrometry (GC/MS) to rapidly quantify quinine in biological samples with cyproheptadine as the internal standard is described. The selected ion monitoring mode, with the quantification ions m/z 136 and 287 (qualifier ions: m/z 261, 381 and 215, 96), allows the estimation of quinine levels, respectively. Separation was completed within 12.7 min. Excellent linearity was found up to 10 000 microg/L of plasma. The limit of detection (LOD) was 12.2 microg/L and the limit of quantification (LOQ) was 40.6 microg/L. High reproducibility (intra-assay CV range 1.9-4.3%, inter-assay CV range 2.2-11.3%) and accuracy values (intra-assay range 83.2-103.7%, inter-assay range 86.8-103.7%) were obtained. Recoveries were concentration-independent (97.2% and 89.8% for 4000 and 10 000 microg/L, respectively). This sensitive, simple assay for quinine in various matrices meets the current requirements for bioanalytical assays and may be used to monitor quinine levels in patients developing severe malaria with acute renal failure during hemofiltration. The optimal quinine dose in this situation is not really established and to improve clinical care, quinine concentrations might be explored to improve efficacy and minimise potential toxicity.

Rapid gas chromatography/mass spectrometry quinine determination in plasma after automated solid-phase extraction.

Neuropathic pain is one of the most debilitating pain conditions, yet no therapeutic strategy has been really effective for its treatment. Hence, a better understanding of its pathophysiological mechanisms is necessary to identify new pharmacological targets. Here, we report important metabolic variations in brain areas involved in pain processing in a rat model of oxaliplatin-induced neuropathy using HRMAS (1)H-NMR spectroscopy. An increased concentration of choline has been evidenced in the posterior insular cortex (pIC) of neuropathic animal, which was significantly correlated with animals' pain thresholds. The screening of 34 genes mRNA involved in the pIC cholinergic system showed an increased expression of the high-affinity choline transporter and especially the muscarinic M2 receptors, which was confirmed by Western blot analysis in oxaliplatin-treated rats and the spared nerve injury model (SNI). Furthermore, pharmacological activation of M2 receptors in the pIC using oxotremorine completely reversed oxaliplatin-induced mechanical allodynia. Consistently, systemic treatment with donepezil, a centrally active acetylcholinesterase inhibitor, prevented and reversed oxaliplatin-induced cold and mechanical allodynia as well as social interaction impairment. Intracerebral microdialysis revealed a lower level of acetylcholine in the pIC of oxaliplatin-treated rats, which was significantly increased by donepezil. Finally, the analgesic effect of donepezil was markedly reduced by a microinjection of the M2 antagonist, methoctramine, within the pIC, in both oxaliplatin-treated rats and spared nerve injury rats. These findings highlight the crucial role of cortical cholinergic neurotransmission as a critical mechanism of neuropathic pain, and suggest that targeting insular M2 receptors using central cholinomimetics could be used for neuropathic pain treatment.

Cholinergic Neurotransmission in the Posterior Insular Cortex Is Altered in Preclinical Models of Neuropathic Pain: Key Role of Muscarinic M2 Receptors in Donepezil-Induced Antinociception.

In clinical and forensic toxicology, fast and specific methods are needed for the screening of different classes of drugs. A complete general unknown screening procedure was developed using turbulent flow chromatography with electrospray ionization and Orbitrap mass spectrometry.

Fully automated semi-quantitative toxicological screening in three biological matrices using turbulent flow chromatography/high resolution mass spectrometry.

The therapeutic activity of drugs can be optimized by establishing an individualized dosage, based on the measurement of the drug concentration in the serum, particularly if the drugs are characterized by an inter-individual variation in pharmacokinetics that results in an under- or overexposure to treatment. In recent years, several tyrosine kinase inhibitors (TKIs) have been developed to block intracellular signaling pathways in tumor cells. These oral drugs are candidates for therapeutic drug monitoring (TDM) due to their high inter-individual variability for therapeutic and toxic effects. Following a literature search on PubMed, studies on TKIs and their pharmacokinetic characteristics, plasma quantification and inter-individual variability was studied. TDM is commonly used in various medical fields, including cardiology and psychiatry, but is not often applied in oncology. Plasma concentration monitoring has been thoroughly studied for imatinib, in order to evaluate the usefulness of TDM. The measurement of plasma concentration can be performed by various analytical techniques, with liquid chromatography-mass spectrometry being the reference method. This method is currently used to monitor the efficacy and tolerability of imatinib treatments. Although TDM is already being used for imatinib, additional studies are required in order to improve this practice with the inclusion of other TKIs.

Therapeutic drug monitoring and tyrosine kinase inhibitors.

Antidepressants are one of the first line treatments for neuropathic pain but their use is limited by the incidence and severity of side effects of tricyclics and the weak effectiveness of selective serotonin reuptake inhibitors (SSRIs). Serotonin type 2A (5-HT) receptors interact with PDZ proteins that regulate their functionality and SSRI efficacy to alleviate pain. We investigated whether an interfering peptide (TAT-2ASCV) disrupting the interaction between 5-HT receptors and associated PDZ proteins would improve the treatment of traumatic neuropathic allodynia. Tactile allodynia was assessed in spinal nerve ligation-induced neuropathic pain in rats using von Frey filaments after acute treatment with TAT-2ASCV and/or 5-HT receptor agonist, alone or in combination with repeated treatment with fluoxetine. In vivo microdialysis was performed in order to examine the involvement of GABA in TAT-2ASCV/fluoxetine treatment-associated analgesia. TAT-2ASCV (100ng, single i.t. injection) improved SNL-induced tactile allodynia by increasing 5-HT receptor responsiveness to endogenous 5-HT. Fluoxetine alone (10mg/kg, five i.p. injections) slightly increased tactile thresholds and its co-administration with TAT-2ASCV (100ng, single i.t. injection) further enhanced the anti-allodynic effect. This effect depends on the integrity of descending serotonergic bulbospinal pathways and spinal release of GABA. The anti-allodynic effect of fluoxetine can be enhanced by disrupting 5-HT receptor-PDZ protein interactions. This enhancement depends on 5-HT receptor activation, spinal GABA release and GABAA receptor activation.

Increasing spinal 5-HT receptor responsiveness mediates anti-allodynic effect and potentiates fluoxetine efficacy in neuropathic rats. Evidence for GABA release.

Antidepressants, prescribed as first line treatment of neuropathic pain, have a limited efficacy and poorly tolerated side effects. Because recent studies pointed out the implication of astroglial connexins (Cx) in both neuropathic pain and antidepressive treatment, we investigated whether their blockade by mefloquine could modulate the action of the tricyclic antidepressant amitriptyline. Using primary cultures, we found that both mefloquine and amitriptyline inhibited Cx43-containing gap junctions, and that the drug combination acted synergically. We then investigated whether mefloquine could enhance amitriptyline efficacy in a preclinical model of neuropathic pain. Sprague-Dawley rats that underwent chronic unilateral constriction injury (CCI) to the sciatic nerve (SN) were treated with either amitriptyline, mefloquine or the combination of both drugs. Whereas acute treatments were ineffective, chronic administration of amitriptyline reduced CCI-SN-induced hyperalgesia-like behavior, and this effect was markedly enhanced by co-administration of mefloquine, which was inactive on its own. No pharmacokinetic interactions between both drugs were observed and CCI-SN-induced neuroinflammatory and glial activation markers remained unaffected by these treatments in dorsal root ganglia and spinal cord. Mechanisms downstream of CCI-SN-induced neuroinflammation and glial activation might therefore be targeted. Connexin inhibition in astroglia could represent a promising approach towards improving neuropathic pain therapy by antidepressants.

Potentiation of Amitriptyline Anti-Hyperalgesic-Like Action By Astroglial Connexin 43 Inhibition in Neuropathic Rats.

Phthalic acid esters have been widely used to improve the plasticity of PVC medical devices. They carry a high exposure risk for both humans and the environment in clinical situations. Our study focuses on the cytotoxicity of alternative plasticizers. Postulated primary metabolites were synthesized, not being commercially available. Cytotoxicity assays were performed on L929 murine cells according to the ISO-EN 10993-5 standard design for the biocompatibility of medical devices. The tested concentrations of plasticizers (0.01, 0.05 and 0.1 mg/ml) covered the range likely to be found in biological fluids coming into direct contact with the medical devices. DEHP, DINP and DINCH were cytotoxic at the highest concentration (0.1 mg/ml) for 7 days of exposure. Their corresponding metabolites were found to be more cytotoxic, for the same concentration. By contrast, TOTM and its corresponding metabolite MOTM were not found to be cytotoxic. DEHA showed no cytotoxicity, but its corresponding monoester (MEHA) produced a cytotoxic effect at 0.05 mg/ml. In clinical situations, medical devices can release plasticizers, which can come into contact with patients. In vivo, the plasticizers are quickly transformed into primary metabolites. It is therefore important to measure the effects of both the plasticizers and their corresponding metabolites. Standard first-line cytotoxicity assays should be performed to ensure biocompatibility.

In vitro cytotoxic effects of DEHP-alternative plasticizers and their primary metabolites on a L929 cell line.

Neurotoxicity remains the most common adverse effect of oxaliplatin, limiting its clinical use. In the present study, we developed a mouse model of chronic oxaliplatin-induced neuropathy, which mimics both sensory and motor deficits observed in patients, in a clinically relevant time course. Repeated oxaliplatin administration in mice induced both cephalic and extracephalic long lasting mechanical and cold hypersensitivity after the first injection as well as delayed sensorimotor deficits and a depression-like phenotype. Using this model, we report that riluzole prevents both sensory and motor deficits induced by oxaliplatin as well as the depression-like phenotype induced by cumulative chemotherapeutic drug doses. All the beneficial effects are due to riluzole action on the TREK-1 potassium channel, which plays a central role in its therapeutic action. Riluzole has no negative effect on oxaliplatin antiproliferative capacity in human colorectal cancer cells and on its anticancer effect in a mouse model of colorectal cancer. Moreover, riluzole decreases human colorectal cancer cell line viability in vitro and inhibits polyp development in vivo. The present data in mice may support the need to clinically test riluzole in oxaliplatin-treated cancer patients and state for the important role of the TREK-1 channel in pain perception.

Article	Year
A one-step and sensitive GC-MS assay for meprobamate determination in emergency situations. Journal of analytical toxicology\| PubMed ID: 16839465	2006
Rapid gas chromatography/mass spectrometry quinine determination in plasma after automated solid-phase extraction. Rapid communications in mass spectrometry : RCM\| PubMed ID: 16878344	2006
Cholinergic Neurotransmission in the Posterior Insular Cortex Is Altered in Preclinical Models of Neuropathic Pain: Key Role of Muscarinic M2 Receptors in Donepezil-Induced Antinociception. The Journal of neuroscience : the official journal of the Society for Neuroscience\| PubMed ID: 26674867	2015
Fully automated semi-quantitative toxicological screening in three biological matrices using turbulent flow chromatography/high resolution mass spectrometry. Clinica chimica acta; international journal of clinical chemistry\| PubMed ID: 26812390	2016
Therapeutic drug monitoring and tyrosine kinase inhibitors. Oncology letters\| PubMed ID: 27446421	2016
Increasing spinal 5-HT receptor responsiveness mediates anti-allodynic effect and potentiates fluoxetine efficacy in neuropathic rats. Evidence for GABA release. Pharmacological research\| PubMed ID: 27663259	2017
Potentiation of Amitriptyline Anti-Hyperalgesic-Like Action By Astroglial Connexin 43 Inhibition in Neuropathic Rats. Scientific reports\| PubMed ID: 27941941	2016
In vitro cytotoxic effects of DEHP-alternative plasticizers and their primary metabolites on a L929 cell line. Chemosphere\| PubMed ID: 28129623	2017
Targeting the TREK-1 potassium channel via riluzole to eliminate the neuropathic and depressive-like effects of oxaliplatin. Neuropharmacology\| PubMed ID: 30056126	2018

Damien Richard

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