Accuracy profile validation of a new analytical method for propane measurement using headspace-gas chromatography-mass spectrometry

Propane can be responsible for several types of lethal intoxication and explosions. Quantifying it would be very helpful to determine in some cases the cause of death. Some gas chromatography-mass spectrometry (GC-MS) methods of propane measurements do already exist. The main drawback of these GC-MS methods described in the literature is the absence of a specific propane internal standard necessary for accurate quantitative analysis. The main outcome of the following study was to provide an innovative Headspace-GC-MS method (HS-GC-MS) applicable to the routine determination of propane concentration in forensic toxicology laboratories. To date, no stable isotope of propane is commercially available. The development of an in situ generation of standards is thus presented. An internal-labeled standard gas (C3DH7) is generated in situ by the stoichiometric formation of propane by the reaction of deuterated water (D2O) with Grignard reagent propylmagnesium chloride (C3H7MgCl). The method aims to use this internal standard to quantify propane concentrations and, therefore, to obtain precise measurements. Consequently, a complete validation with an accuracy profile according to two different guidelines, the French Society of Pharmaceutical Sciences and Techniques (SFSTP) and the Gesellschaft für toxikologische und Forensische Chemie (GTFCh), is presented.

Distribution profile of zwitterions and hydrolysis of esters derived from N-benzylpiperazine

Résumé Les esters sont des agents thérapeutiques largement utilisés comme médicaments et prodrogues. Leurs dégradation est chimique et enzymatique. Le Chapitre IV de cette thèse a comme objet l'hydrolyse chimique de plusieurs dérivés esters du 2,3-dimethoxyphenol. Des composés modèles ont été synthétisés dans le but de déterminer leur mécanismes de dégradation. Les profils d'ionisation et d'hydrolyse de ces composés ont permis d'identifier la présence d'une catalyse intramoléculaire basique par un atome d'azote non-protoné. Les effets électroniques exercés par les groupes phenylethenyle et phenylcyclopropyle influencent également la vitesse d'hydrolyse des esters. La résolution des problèmes liés à l'adsorption et la perméation est devenue à nos jours l'étape limitante dans la conception de nouveaux médicaments car de trop nombreux candidats prometteurs ont échoué à cause d'une mauvaise biodisponibilité. La lipophilie décrit le partage d'un médicament entre une membrane lipidique et son environnement physiologique aqueux, et de ce fait elle influence sa pharmacocinétique. Des études récents ont mis en évidence l'importance de la détermination de la lipophilie des espèces ionisées vu leur considérable impact biologique. Le Chapitre V de cette thèse est centré sur une classe particulière de composés ionisables, les zwitterions. Plusieurs methoxybenzylpiperazines de nature zwitterionique ont été étudiées. Leurs profils d'ionisation ont montré que dans un large intervalle de pH, l'espèce prédominante est le zwitterion. Les profils de lipophilie ont montré que leur lipophilie est plus élevée que celles des zwitterions courants. Une interaction électrostatique entre l'oxygène du carboxylate et l'azote protoné est responsable de ce profil et rend la plupart des zwitterions non-donneurs de liaison hydrogène. Ces deux aspects peuvent favoriser le passage de la barrière hémato-éncephalique. Les données biologiques ont par la suite confirmé cette hypothèse pour un certain nombre de composés. Résumé large public Les esters sont des composés souvent rencontrés en chimie thérapeutique. Ils sont dégradés en milieu aqueux par une réaction d'hydrolyse, avec ou sans la participation d'enzymes. Dans ce travail de thèse, une série d'esters ont été étudiés dans le but d'établir une relation entre leur structure et les mécanismes responsables de leur dégradation chimique. Il a été prouvé que la dégradation est accélérée par un atome d'azote non-protoné. D'autres mécanismes peuvent intervenir en fonction du pH du milieu. La présence d'une liaison simple ou double ou d'un groupe phenylcyclopropyle peut également influencer la vitesse de dégradation. Il est essentiel, dans la conception de nouveaux médicaments, d'optimiser les étapes qui influencent leur distribution dans le corps. Ce dernier peut être visualisé comme une série infinie de compartiments aqueux séparés par des membranes lipidiques. La lipophilie est une propriété moléculaire importante qui décrit le passage des barrières rencontrées par les médicaments. Des études récentes ont mis en évidence l'importance de déterminer la lipophilie des espèces ionisées vu leur considérable impact biologique. Dans ce travail de thèse a été étudiée une série particulière de composés ionisables , les zwitterions. Une relation a été établie entre leur structure et leur proprietés physico-chimiques. Une lipophilie plus élevée par rapport à celle des zwitterions courants a été trouvée. Une interaction entre les groupes chargés des zwitterions étudiés est responsable de ce comportement inattendu et rend la plupart d'entre eux non-donneurs de liaison hydrogène. Ces deux facteurs peuvent favoriser la pénétration cérébrale. Les données biologiques ont confirmé cette hypothèse pour un certain nombre de composés. Summary Esters are often encountered in medicinal chemistry. Their hydrolysis may be chemical as well as enzymatic. Chapter IV of this manuscript provides a mechanistic insight into the chemical hydrolysis of a particular series of basic esters derived from 2,3-dimethoxyphenol. Their ionization and pH-rate profiles allowed to identify the presence of an intramolecular base catalysis by a non-protonated nitrogen atom. Electronic effects exerted by the phenylethenyl and phenylcyclopropyl groups that are present in the structure of the esters also influenced their rate of hydrolysis. Numerous works in the literature witness of the importance of lipophilicity in determining the fate of a drug. Most published partition coefficients are those of neutral species. In contrast, no exhaustive treatment of the lipophilicity of charged molecules is available at present, and a lack of information characterizes in particular zwitterions. Chapter V of this manuscript provides an insight into the physicochemical parameters of a series of zwitterionic methoxybenzylpiperazines. Their ionization profiles showed that they exist predominantly in the zwitterionic form in a broad pH-range. An electrostatic interaction between the oxygen of the carboxylate and the protonated nitrogen atom is increases the lipophilicity of the investigated zwitterions, and prevents the majority of them to express their hydrogen-bonding capacity. These two aspects may favor the crossing of the blood-brain barrier. The available ratios PSt/PSf measured in vitro have confirmed this point for a number of compounds.

Evolution of the neurochemical profile after transient focal cerebral ischemia in the mouse brain.

Evolution of the neurochemical profile consisting of 19 metabolites after 30 mins of middle cerebral artery occlusion was longitudinally assessed at 3, 8 and 24 h in 6 to 8 microL volumes in the striatum using localized 1H-magnetic resonance spectroscopy at 14.1 T. Profound changes were detected as early as 3 h after ischemia, which include elevated lactate levels in the presence of significant glucose concentrations, decreases in glutamate and a transient twofold glutamine increase, likely to be linked to the excitotoxic release of glutamate and conversion into glial glutamine. Interestingly, decreases in N-acetyl-aspartate (NAA), as well as in taurine, exceeded those in neuronal glutamate, suggesting that the putative neuronal marker NAA is rather a sensitive marker of neuronal viability. With further ischemia evolution, additional, more profound concentration decreases were detected, reflecting a disruption of cellular functions. We conclude that early changes in markers of energy metabolism, glutamate excitotoxicity and neuronal viability can be detected with high precision non-invasively in mice after stroke. Such investigations should lead to a better understanding and insight into the sequential early changes in the brain parenchyma after ischemia, which could be used for identifying new targets for neuroprotection.

Risk factor profile and management of cerebrovascular patients in the REACH Registry.

BACKGROUND: Cerebrovascular disease (CVD) is a global public health problem. CVD patients are at high risk of recurrent stroke and other atherothrombotic events. Prevalence of risk factors, comorbidities, utilization of secondary prevention therapies and adherence to guidelines all influence the recurrent event rate. We assessed these factors in 18,992 CVD patients within a worldwide registry of stable outpatients. METHODS: The Reduction of Atherothrombosis for Continued Health Registry recruited >68,000 outpatients (44 countries). The subjects were mainly recruited by general practitioners (44%) and internists (29%) if they had symptomatic CVD, coronary artery disease, peripheral arterial disease (PAD) and/or >or=3 atherothrombotic risk factors. RESULTS: The 18,992 CVD patients suffered a stroke (53.7%), transient ischemic attack (TIA) (27.7%) or both (18.5%); 40% had symptomatic atherothrombotic disease in >or=1 additional vascular beds: 36% coronary artery disease; 10% PAD and 6% both. The prevalence of risk factors at baseline was higher in the TIA subgroup than in the stroke group: treated hypertension (83.5/82.0%; p = 0.02), body mass index >or=30 (26.7/20.8%; p < 0.0001), hypercholesterolemia (65.1/52.1%; p < 0.0001), atrial fibrillation (14.7/11.9%; p < 0.0001) and carotid artery disease (42.3/29.7%; p < 0.0001). CVD patients received antiplatelet agents (81.7%), oral anticoagulants (17.3%), lipid-lowering agents (61.2%) and antihypertensives (87.9%), but guideline treatment targets were frequently not achieved (54.5% had elevated blood pressure at baseline, while 4.5% had untreated diabetes). CONCLUSIONS: A high percentage of CVD patients have additional atherothrombotic disease manifestations. The risk profile puts CVD patients, especially the TIA subgroup, at high risk for future atherothrombotic events. Undertreatment is common worldwide and adherence to guidelines needs to be enforced.

Road Profile Adjustment Computer Program, HR-143, 1969

A computer program to adjust roadway profiles has been developed to serve as an aid to the county engineers of the State of Iowa. Many hours are spent reducing field notes and calculating adjusted roadway profiles to prepare an existing roadway for paving that will produce a high quality ride and be as maintenance free as possible. Since the computer is very well adapted to performing long tedious tasks; programming this work for a computer would result in freeing the engineer of these tasks. Freed from manual calculations, the engineer is able to spend more time in solving engineering problems. The type of roadway that this computer program is designed to adjust is a road that at sometime. in its history was graded to a finished subgrade. After a period of time, this road is to receive a finished paved surface. The problem then arises whether to bring the existing roadway up to the de signed grade or to make profile adjustments and comprise between the existing and the design profiles. In order to achieve the latter condition using this program, the engineer needs to give the computer only a minimum amount of information.

Differential effects of pro- and anti-inflammatory cytokines alone or in combinations on the metabolic profile of astrocytes.

We have previously reported that the pro-inflammatory cytokines tumor necrosis factor-α (TNFα) and interleukin-1β (IL-1β) induce profound modifications of the metabolic profile of astrocytes. The present study was undertaken to further characterize the effects of cytokines in astrocytes and to determine whether similar effects could also be observed in neurons. To do so, selected pro-inflammatory (IL-6 and interferon-γ, in addition to the above-mentioned TNFα and IL-1β) and anti-inflammatory cytokines (IL-4, IL-10, transforming growth factor-β1 and interferon-β) were applied to primary neuronal and astrocytic cultures, and key metabolic parameters were assessed. As a general pattern, we observed that pro-inflammatory cytokines increased glucose utilization in astrocytes while the anti-inflammatory cytokines IL-4 and IL-10 decreased astrocytic glucose utilization. In contrast, no significant change could be observed in neurons. When pairs of pro-inflammatory cytokines were co-applied in astrocytes, several additive or synergistic modifications could be observed. In contrast, IL-10 partially attenuated the effects of pro-inflammatory cytokines. Finally, the modifications of the astrocytic metabolism induced by TNFα + IL-1β and interferon-γ modulated neuronal susceptibility to an excitotoxic insult in neuron-astrocyte co-cultures. Together, these results suggest that pro- and anti-inflammatory cytokines differentially affect the metabolic profile of astrocytes, and that these changes have functional consequences for surrounding neurons.

Low Profile Marker for Wet/Night Visibility, HR-1005, 1977

Conventional highway lane markings are ineffective at night, particularly when the pavement is wet. There is a recognized need for a system that is effective at night under wet conditions and where there is no reduction in current daytime standards. To be effective at all times the system must maintain wet-night retroreflective properties while resisting deterioration caused by snowplows, studded tires, sand and salt applications, and lane changing maneuvers by traffic. This project tested a system of low-profile lane markers developed by Battelle Columbus Laboratory under contract with the Implementation Division of the Federal Highway Administration.

Predicting the physicochemical profile of diastereoisomeric histidine-containing dipeptides by property space analysis.

OBJECTIVES: This study aimed at measuring the lipophilicity and ionization constants of diastereoisomeric dipeptides, interpreting them in terms of conformational behavior, and developing statistical models to predict them. METHODS: A series of 20 dipeptides of general structure NH(2) -L-X-(L or D)-His-OMe was designed and synthetized. Their experimental ionization constants (pK(1) , pK(2) and pK(3) ) and lipophilicity parameters (log P(N) and log D(7.4) ) were measured by potentiometry. Molecular modeling in three media (vacuum, water, and chloroform) was used to explore and sample their conformational space, and for each stored conformer to calculate their radius of gyration, virtual log P (preferably written as log P(MLP) , meaning obtained by the molecular lipophilicity potential (MLP) method) and polar surface area (PSA). Means and ranges were calculated for these properties, as was their sensitivity (i.e., the ratio between property range and number of rotatable bonds). RESULTS: Marked differences between diastereoisomers were seen in their experimental ionization constants and lipophilicity parameters. These differences are explained by molecular flexibility, configuration-dependent differences in intramolecular interactions, and accessibility of functional groups. Multiple linear equations correlated experimental lipophilicity parameters and ionization constants with PSA range and other calculated parameters. CONCLUSION: This study documents the differences in lipophilicity and ionization constants between diastereoisomeric dipeptides. Such configuration-dependent differences are shown to depend markedly on differences in conformational behavior and to be amenable to multiple linear regression. Chirality 24:566-576, 2012. © 2012 Wiley Periodicals, Inc.

Esterase profile in the postembryonic development of Rhipicephalusmicroplus

The objective of this work was to analyze the pattern of esterase activity in the development stages of Rhipicephalus microplus by nondenaturing polyacrylamide gel electrophoresis using specific staining for esterase. The electrophoretical results revealed the presence of nine regions displaying esterase activity, stained with both alpha-naphthyl acetate and beta-naphthyl acetate, and classified as alpha-beta-esterase. Stage-specific esterases were found, with the first nymphal and larval stages showing the greatest esterase activity throughout the development. An esterase called EST-4 was detected only in males and was considered sex-specific. There are differences in the esterase profile among the different postembryonic development stages of R. microplus.

Valproate treatment of human cord blood CD4-positive effector T cells confers on them the molecular profile (microRNA signature and FOXP3 expression) of natural regulatory CD4-positive cells through inhibition of histone deacetylase.

Regulatory T cells (Tregs) play a key role in immune system homeostasis and tolerance to antigens, thereby preventing autoimmunity, and may be partly responsible for the lack of an appropriate immune response against tumor cells. Although not sufficient, a high expression of forkhead box P3 (FOXP3) is necessary for their suppressive function. Recent reports have shown that histones deacetylase inhibitors increased FOXP3 expression in T cells. We therefore decided to investigate in non-Tregs CD4-positive cells, the mechanisms by which an aspecific opening of the chromatin could lead to an increased FOXP3 expression. We focused on binding of potentially activating transcription factors to the promoter region of FOXP3 and on modifications in the five miRs constituting the Tregs signature. Valproate treatment induced binding of Ets-1 and Ets-2 to the FOXP3 promoter and acted positively on its expression, by increasing the acetylation of histone H4 lysines. Valproate treatment also induced the acquisition of the miRs Tregs signature. To elucidate whether the changes in the miRs expression could be due to the increased FOXP3 expression, we transduced these non-Tregs with a FOXP3 lentiviral expression vector, and found no changes in miRs expression. Therefore, the modification in their miRs expression profile is not due to an increased expression of FOXP3 but directly results from histones deacetylase inhibition. Rather, the increased FOXP3 expression results from the additive effects of Ets factors binding and the change in expression level of miR-21 and miR-31. We conclude that valproate treatment of human non-Tregs confers on them a molecular profile similar to that of their regulatory counterpart.

Iowa State Profile Tool: An Assessment of Iowa's Long-Term Support System, March 31, 2009

The Iowa State Profile Tool is a comprehensive, high-level assessment of Iowa’s progress toward a balanced long-term care system – a system that relies less on institutional services and provides greater opportunities for the in-home and community-based services that most people prefer. This report includes long-term support for people of all ages and disability types and is based on a variety of state and federal data sources and interviews with public and private leaders in Iowa’s long-term care system.

Organic geochemistry of Jurassic-Cretaceous source rocks and oil seeps from the profile across the Adriatic-Dinaric carbonate platform

Organic geochemical and stable isotope investigations were performed to provide an insight into the depositional environments, origin and maturity of the organic matter in Jurassic and Cretaceous formations of the External Dinarides. A correlation is made among various parameters acquired from Rock-Eval, gas chromatography-mass spectrometry data and isotope analysis of carbonates and kerogen. Three groups of samples were analysed. The first group includes source rocks derived from Lower Jurassic limestone and Upper Jurassic ``Leme'' beds, the second from Upper Cretaceous carbonates, while the third group comprises oil seeps genetically connected with Upper Cretaceous source rocks. The carbon and oxygen isotopic ratios of all the carbonates display marine isotopic composition. Rock-Eval data and maturity parameter values derived from biomarkers define the organic matter of the Upper Cretaceous carbonates as Type I-S and Type II-S kerogen at the low stage of maturity up to entering the oil-generating window. Lower and Upper Jurassic source rocks contain early mature Type III mixed with Type IV organic matter. All Jurassic and Cretaceous potential source rock extracts show similarity in triterpane and sterane distribution. The hopane and sterane distribution pattern of the studied oil seeps correspond to those from Cretaceous source rocks. The difference between Cretaceous oil seeps and potential source rock extracts was found in the intensity and distribution of n-alkanes, as well as in the abundance of asphaltenes which is connected to their biodegradation stage. In the Jurassic and Cretaceous potential source rock samples a mixture of aromatic hydrocarbons with their alkyl derivatives were indicated, whereas in the oil seep samples extracts only asphaltenes were observed.

Rapid Improvement and Maintenance of the Lipid Profile After Roux-en-Y Gastric Bypass (RYGBP)

Background: Dyslipidemia, a major component of the metabolic syndrome and an important cardiovascular risk factor, is one of the commonest comorbidity associated with morbid obesity. The aim of this paper is to show that RYGBP markedly improves dyslipidemia and that this improvement maintains over time. Patients and Methods: Prospectively updated databank for bariatric patients. Patients undergoing RYGBP have yearly blood tests during follow-up. The results for lipids at one to five years were compared with preoperative values. Results: The mean excess BMI loss after one and five years was 77,9 % and 72,3%respectively. After one year, there was a significant reduction of the mean total cholesterol, LDL-cholesterol, total cholesterol/HDL ratio and triglyceride values, which maintained up to five years, and an increase of the HDL fraction, which progressed until five years. The proportion of patients with abnormal values decreased from 24,3 to 6,2% for total cholesterol, from 45,1 to 11,7 %for HDL, from 53,3 to 21,9 for LDL, and from 40,5 to 10 % for triglycerides, with no significant change between three and five years, despite some weight regain. Conclusions: RYGBP rapidly improves all components of dyslipidemia, and thereby reduces the overall cardiovascular risk in operated patients.

Raman analysis of multilayer automotive paints in forensic science: measurement variability and depth profile?

The aim of this work is to study the influence of several analytical parameters on the variability of Raman spectra of paint samples. In the present study, microtome thin section and direct (no preparation) analysis are considered as sample preparation. In order to evaluate their influence on the measures, an experimental design such as 'fractional full factorial' with seven factors (including the sampling process) is applied, for a total of 32 experiments representing 160 measures. Once the influence of sample preparation highlighted, a depth profile of a paint sample is carried out by changing the focusing plane in order to measure the colored layer under a clearcoat. This is undertaken in order to avoid sample preparation such a microtome sectioning. Finally, chemometric treatments such as principal component analysis are applied to the resulting spectra. The findings of this study indicate the importance of sample preparation, or more specifically, the surface roughness, on the variability of the measurements on a same sample. Moreover, the depth profile experiment highlights the influence of the refractive index of the upper layer (clearcoat) when measuring through a transparent layer.