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At least 217 records · Page 12Linked to original sources
PubMed1986

Gas chromatographic and gas chromatographic-mass spectrometric determination of gasoline in a case of gasoline vapor and alcohol poisoning.

A case of fatal poisoning due to the combined effect of alcohol and gasoline following an automobile accident is described. Toxicological analyses by means of gas chromatography and gas chromatography-mass spectrometry permitted the identification and quantitation of alcohol and several hydrocarbons in the heart blood and in the gas in the lung. Great variation was found in the estimates of blood gasoline concentration, depending on which of six constituents of gasoline was chosen for quantitation. The cause of this variation is discussed, together with the possible mechanisms leading to death.

Adult↗
PubMed1967

Identification of fatty acids and aliphatic hydrocarbons in Sarcina lutea by gas chromatography and combined gas chromatography-mass spectrometry.

The composition and nature of the fatty acids and hydrocarbons of Sarcina lutea were elucidated by gas chromatography and by combined gas chromatography-mass spectrometry. The distribution of fatty acids found in S. lutea showed two families of pairs, or dyads, of saturated monocarboxylic acids (C12-C18) with and without methyl branching. These pairs of fatty acids showed a pattern of iso and anteiso structures for C13, C15, and C17, and iso and normal structures for C12, C14, and C16. Only the C18 showed unsaturation. The distribution of hydrocarbons in the range C22-C29 showed two families of tetrads of unsaturated aliphatic hydrocarbons all showing methyl branching. Each tetrad was composed of four isomers identified as two iso olefins and two anteiso olefins. The only difference between the tetrads pertaining to different families was found in the relative gas chromatographic retention times of the last two components of each group.

Chromatography, Gas↗
PubMed1975

Gas-blood PCO2 gradients during avian gas exchange.

The avian respiratory system is a crosscurrent gas exchange system. One of the aspects of this type of gas exchange system is that end-expired PCO2 is greater than arterial PCO2, the highest possible value being equal to mixed venous PCO2. We made steady-state measurements of arterial, mixed venous, and end-expired PCO2 in anesthetized, spontaneously breathing chickens during inhalation of room air or 4-8% CO2. We found end-expired PCO2 to be higher than both arterial and mixed venous PCO2, the sign of the differences being such as to oppose passive diffusion. The observation that end-expired PCO2 was higher than arterial PCO2 can be explained on the basis of crosscurrent gas exchange. However, the observation that end-expired PCO2 exceeded mixed venous PCO2 must be accounted for by some other mechanism. The positive end-expired to mixed venous PCO2 gradients can be explained if it is postulated that the charged membrane mechanism suggested by Gurtner et al. (Respiration Physiol. 7: 173-187, 1969) is present in the avian lung.

Acetazolamide↗
PubMed1988

Correction of inert gas washin or washout for gas solubility in blood.

We show that when an inert gas is washed into the lungs its retention in the blood during any one breath is approximately proportional to its solubility. This relationship makes possible the correction of washin or washout data for blood uptake or release, provided that two gases of different solubility are used simultaneously. The method automatically allows for the characteristics of an individual washin or washout and for the occurrence of recirculation within a fairly short washin or washout period. It has been tested in models with nonuniform ventilation and perfusion and closely approximates the behavior of a truly insoluble gas. In the derived ventilation distribution, gas solubility appears as ventilation to units of low turnover. In the case of N2 this effect is small but causes appreciable overestimation of lung volume. The recovered dead space and main alveolar distribution are insignificantly affected.

Cardiac Output↗
PubMed1978

Gas identity hazards and major contamination of the medical gas system of a new hospital.

During commissioning of the medical gas system of a new hospital, fourteen connection defects were found; six of these were potentially lethal cross-connections. A major contaminant was also detected throughout the medical gas system. The methods of testing a new medical gas system described in this report highlight the need for up-grading of existing standards.

Australia↗
PubMed2003

Prediction of arterial blood gas values from venous blood gas values in patients with acute respiratory failure receiving mechanical ventilation.

BACKGROUND AND PURPOSE: Arterial blood gas (ABG) analysis is useful in evaluation of the clinical condition of critically ill patients; however, arterial puncture or insertion of an arterial catheter may cause many complications. This study evaluated whether pH, partial pressure of carbon dioxide (PCO2) and bicarbonate (HCO3-) values of venous blood gas (VBG) could accurately predict their ABG analogs for patients with acute respiratory failure treated by mechanical ventilation in an intensive care unit (ICU). METHODS: Forty six patients who were admitted to the ICU due to acute respiratory failure and treated by mechanical ventilation were included in this study. Blood for VBG analysis was sampled from the cubital or dorsal palmar veins, while ABG was sampled simultaneously from the radial or brachial arteries via an arterial catheter at the other upper extremity. Regression equations and mean percentage-difference equations were derived to predict arterial pH, PCO2, and HCO3- values from their VBG analogs. The equations were validated by evaluating VBG and ABG samples from a separate group of 11 patients. RESULTS: A total of 46 paired samples from 46 patients were evaluated. The mean percentage differences between the venous and arterial values divided by venous values for pH, PCO2, and HCO3- were (mean +/- SD): deltapH (%), 0.50 +/- 0.45; deltaPCO2 (%), 17.09 +/- 9.60; and deltaHCO3- (%), 9.72 +/- 7.73; respectively. Regression equations for prediction of pH, PCO2 and HCO3- values were: arterial pH (pHa) = 0.45 + 0.94 x venous pH (pHv) [r = 0.83, p < 0.0001]; partial pressure of arterial CO2 (PaCO2) = 3.06 + 0.76 x partial pressure of venous CO2 (PvCO2) [r = 0.86, p < 0.0001]; and arterial HCO3- (HCO3-a) = 2.34 + 0.82 x venous HCO3- (HCO3-v) [r = 0.91, p < 0.0001]. The predicted ABG values from the mean percentage-difference equations were derived as follows: pHa = pHv x 1.005; PaCO2 = PvCO2 x 0.83; and HCO3-a = HCO3-v x 0.90. Validation of the regression equations and mean percentage-difference equations revealed only a small (clinically insignificant) variation between the actual and predicted ABG values. CONCLUSIONS: Venous blood gas can accurately predict the ABG values of pH, PCO2 and HCO3- for patients with acute respiratory failure being treated with mechanical ventilation.

Acute Disease↗
PubMed2005

Identification of schizophrenic patients by examination of body odor using gas chromatography-mass spectrometry and a cross-selective gas sensor array.

BACKGROUND: Previous findings have shown that the body odor of patients affected by schizophrenia contains some specific compounds. Chemical sensor technology has proved to be able to classify different odours. We investigated the possibility of using a chemical sensor array to detect body odor alteration in schizophrenic patients. MATERIAL/METHODS: The sweat of subjects was sampled and analysed by Gas Chromatography-Mass Spectrometry (GC-MS) and by an array of cross-selective gas sensors. A total of 27 individuals were involved in the experiment: 9 schizophrenics, 9 with other mental disorders, and 9 controls. RESULTS: GC-MS analysis showed a richer composition for the sweat of schizophrenic patients. Nevertheless, the individuation of specific markers was unsuccessful. On the other hand, statistical analysis of cross-selective gas sensor data provided a complete classification of schizophrenic patients with respect to the other three groups. CONCLUSIONS: The alteration of body odor in schizophrenic patients was confirmed by GC-MS and chemical sensor array. Results show that the alteration is complex and cannot be limited to a single compound, but rather to a global variation of the body odor.

Adult↗
PubMedDate not supplied

[Inert gas study of heliox gas exchange in patients with COPD].

Ventilation and perfusion distributions were measured in the patients with COPD breathing room air and normoxic helium-oxygen mixture (heliox) successively, using the multiple inert gas method. The D (A-a) O2 were calculated from ideal alveolar gas (Ai) and with West's gas mean model (A). Measured PaO2 and predicted PaO2 were compared during room air and heliox breathing. There were no change in overall distributions and in D (Ai-a) while D (A-a) O2 increase significantly during heliox breathing and the predicted PaO2 were significantly higher than the measured PaO2. Heliox breathing does not seem to change parallel heterogeneity in COPD. These results suggest an impairment of series heterogeneity and O2 diffusion during heliox breathing.

Helium↗
PubMed1994

A liquid-liquid blood-gas exchange for the treatment of acute respiratory failure. A new blood gas exchange using artificial blood as an oxygen carrier.

A new liquid-liquid blood gas exchange system was investigated using a venovenous low flow extracorporeal circuit. A 2 m2 hollow fiber dialyzer served as the interface of the blood and oxygen carrier (a 38 percent FC-43, perfluorocarbon emulsion in a buffered electrolyte solution), which was continuously recycled through a bubble oxygenator. Experiments were performed on five mongrel dogs under general anesthesia. Upon the arrest of spontaneous ventilation, the dogs' lungs were inflated with 50% oxygen gas under a positive pressure of 10 cmH2O. After 10 min of apnea the dogs' PaO2 decreased to 37 +/- 14 mmHg, and the extracorporeal circulation was started at 10 ml/min/kg b./w. At 15 min the PaO2 had risen to 80 +/- 41 mmHg and at 30 min to 121 +/- 17 mmHg. The oxygen transfer was 8.3 +/- 2.3 ml/min. The extracorporeal circulation was continued 5h, when PaO2 reached 156 +/- 90 mmHg, and PaCO2 148 +/- 43 mmHg, then stopped. Fifteen minutes later, the PaO2 had returned to 32 +/- 10 mmHg. These findings indicate that our blood gas exchange system can supply a sufficient amount of oxygen to the body under apnea with continuous positive airway pressure.

Animals↗
PubMedDate not supplied

[Gas chromatographic method for determining esterase activity of proteolytic enzymes using continuous gas extraction of the volatile product].

A new procedure was developed for estimating the esterase activity of proteolytic enzymes by using CIS subcomponent of complement and N-alpha-benzoyl-L-arginine ethyl ester as a substrate. In contrast to other methods, which used static variants of gas chromatographic vapour-phase analysis for registration of the volatile reaction product alcohol, the procedure involved steady gas extraction of the volatile product in the gas stream over the incubation mixture. This method enabled to obtain a kinetic curve during one experiment as well as to elevate the accuracy of enzymatic activity estimation.

Arginine↗
PubMed2000

Ethanol production from xylose with the yeast Pichia stipitis and simultaneous product recovery by gas stripping using a gas-lift loop fermentor with attached side-arm (GLSA).

The bioconversion of xylose into ethanol with the yeast Pichia stipitis CBS 5773 is inhibited when 20 g/L of ethanol are present in the fermentation broth. In order to avoid this limitation, the fermentation was carried out with simultaneous recovery of product by CO(2) stripping. The fermentation was also improved by attaching a side-arm to the main body of a classical gas-lift loop fermentor. This side-arm increases the liquid circulation, mass transfer, and gas distribution, reducing the amount of oxygen in the inlet gas necessary to perform the fermentation of xylose under microaerobic conditions (K(L)a approximately 16 h(-1)). The continuous stripping of ethanol from the fermentation broth in this new bioreactor system allowed the consumption of higher xylose concentrations than using Erlenmeyer shaker flasks, improved significantly the process productivity and provided a clean ethanol solution by using an ice-cooled condenser system. Finally, a fed-batch fermentation was carried out with a K(L)a = 15.8 h(-1). Starting with 248.2 g of xylose, 237.6 g of xylose was consumed to produce 88.1 g of ethanol which represents 72.6% of the theoretical yield (47.2 g/L of ethanol was recovered in the condenser, while 9.6 g/L remained in the fermentation broth).

Air Movements↗
PubMed1996

New approaches on gas phase molecular absorption spectrometry detection in gas chromatography.

A hyphenated technique for coupling a spectrophotometric detector to a gas chromatograph with a packed column is described. The packed column was connected directly to the flow cell (path length 1 cm) which was placed in a UV-visible molecular absorption spectrophotometer with diode array detector. This detection system was employed for separating and determining benzene, toluene, 1,4-xylene, 1,2-xylene and mesitylene. Molecular absorption spectra of all the separated compounds have also been obtained. A new possibility for coupling capillary gas chromatography and gas phase molecular absorption spectrometry is currently being tested. In this new case, two fibre optics are used and the measurement is performed in the capillary column.

Journal Article↗
PubMed2004

Cometabolic reduction of bromate by a mixed culture of microorganisms using hydrogen gas in a gas-lift reactor.

The discharge of bromate, a suspected carcinogen, will be restricted in the near future. To assess the possibility of biotechnological treatment of bromate-containing wastewaters, the removal of bromate by chlorate-reducing microorganisms was studied. The removal of bromate and chlorate was studied in laboratory gas-lift bioreactors supplied with hydrogen gas as electron donor in the absence of molecular oxygen. In these reactors, bromate was reduced cometabolically by chlorate-respiring microorganisms. To allow the cometabolic reduction of bromate, a chlorate:bromate molar ratio of at least 3:1 was required. The cometabolic conversion permitted almost complete reduction of bromate into bromide at hydraulic retention times of at least 6 h. Optimal bromate reduction activity was observed at approximately 35 degrees C. The pH optimum was between 7 and 8. Bromate reduction in excess of 80% and a maximum bromate reduction rate of 2.3 g l(-1) day(-1) in a pilot-scale gas-lift bioreactor demonstrates that the process is sustainable.

Air Pollutants↗
PubMed1979

Gas exchange abnormalities produced by venous gas emboli.

Bubbles of either He, N2 or SF6 were infused intravenously into anesthetized dogs at a rate of 0.2 ml/kg/min. Alterations in pulmonary gas exchange were quantitated by the invert gas elimination method during control, steady state infusion and resolution phases. The hypoxemia produced was predominantly due to regions of low VA/Q rather than pure shunt, and the increase in physiological dead space was due to the addition of high VA/Q regions rather than 'pure' dead space. The VA/Q distribution returned to normal within 30 minutes of stopping the He or N2 bubbles, but remained abnormal for longer periods with SF6 bubbles. The net elimination of insoluble gases (such as He or N2) was only slightly impaired by bubble emboli, provided the cardiac output remained constant. Early pulmonary edema from bubble embolization was documented by increased wet weight/dry weight ratio, but the increased lung water was not apparent on histological examination. This form of pulmonary embolus is unique in that there is a constant fraction of the vasculature blocked although any given region with embolus is undergoing continuous resportion of the bubble. This produced a partial obstruction of the affected gas exchange units which manifests as regions of high VA/Q rather than pure dead space.

Animals↗
PubMed1995

Cytogenetic studies of stainless steel welders using the tungsten inert gas and metal inert gas methods for welding.

Cytogenetic damage was studied in lymphocytes from 23 welders using the Tungsten Inert Gas (TIG), and 21 welders using the Metal Inert Gas (MIG) and/or Metal Active Gas (MAG) methods on stainless steel (SS). A matched reference group I, and a larger reference group II of 94 subjects studied during the same time period, was established for comparison. Whole blood conventional cultures (CC), cultures in which DNA synthesis and repair were inhibited (IC), and the sister chromatid exchange (SCE) assay were applied in the study. For the CC a statistically significant decrease in chromosome breaks and cells with aberrations was found for both TIG/SS and MIG/MAG/SS welders when compared with reference group II. A non-significant decrease was found for the corresponding parameters for the two groups of welders when compared with their matched referents. A statistically significant negative association was found between measurements of total chromium (Cr) in inhaled air and SCE, and a weaker negative correlation with hexavalent Cr (Cr(VI)) in air. In conclusion, no cytogenetic damage was found in welders exposed to the TIG/SS and MIG/MAG/SS welding fumes with low content of Cr and Ni. On the contrary, a decline in the prevalence of chromosomal aberrations was indicated in the TIG/SS and MIG/MAG/SS welders, possibly related to the suggested enhancement of DNA repair capacity at slightly elevated exposures.

Adult↗
PubMed2006

Observation of zwitterion formation in the gas-phase H/D-exchange with CH(3)OD: solution-phase structures in the gas phase.

Infrared spectroscopy of gas-phase singly deuterated [Trp + K](+) (formed by H/D exchange with CH(3)OD) shows that some (approximately 20%) kinetically stable zwitterionic (ZW) conformer is formed, based on the diagnostic antisymmetric CO stretch of the deprotonated carboxylate moiety, upsilon(as)(CO(2)(-)), at 1680 cm(-1). A majority of the deuterated [Trp + K](+) is found to be in the charge solvation (CS) conformation, with deuterium exchange occurring on both the acid and amino groups, which is consistent with H/D scrambling. Interestingly, H/D exchange with the more basic ND(3) reagent did not result in the stabilization of a kinetically stable zwitterion, although it is not clear yet what causes this observation. The result for CH(3)OD shows that H/D exchange can in fact alter the structure of the analyte and, hence, care needs to be taken when interpreting gas-phase H/D exchange studies. Moreover, this result shows the possibility of forming solution-phase structures that are thermodynamically disfavored in the gas phase, thus opening a new area of study.

Deuterium↗
PubMed2001

Chiral recognition in gas-phase cyclodextrin: amino acid complexes--is the three point interaction still valid in the gas phase?

The validity of the "three-point interaction" model is examined in the guest exchange reaction involving complexes of cyclodextrins and amino acids. The amino acid guest is exchanged in the gas phase in the presence of a gaseous alkyl amine. The net reaction is proton transfer between the protonated amino acid and the alkyl amine. The amino acid is lost as a neutral species. This reaction is sensitive to the chirality of the amino acid. Several amino acids are examined as well as the respective methyl esters to determine the role of the three interacting groups (ammonium, carboxylic acid, and side chain) in enantioselectivity. We find that the three-point interaction model is indeed valid in the gas phase. Enantioselectivity is optimal when two points of attraction and one repulsion is present in the gas-phase complex. The results are supported by molecular modeling calculations. A mechanism for the exchange is proposed.

Amines↗
PubMed2003

A strain isolated from gas oil-contaminated soil displays chemotaxis towards gas oil and hexadecane.

In this report we describe the isolation of a strain from soil contaminated with gas oil by taking bacteria from a chemotactic ring on gas oil-containing soft agar plates. Partial 16 S rDNA sequencing of the isolated strain showed 99.1% identity with Flavimonas oryzihabitans. It was not only able to degrade different aliphatic hydrocarbons but it was also chemotactic towards gas oil and hexadecane, as demonstrated by the use of three different chemotaxis methods, such as agarose plug and capillary assays and swarm plate analysis. In addition, the strain was chemotactic to a variety of carbon sources that serve as growth substrates, including glucose, arabinose, mannitol, glycerol, gluconate, acetate, succinate, citrate, malate, lactate and casaminoacids. This is the first report on chemotaxis of a hydrocarbon-degrading bacterium towards a pure alkane, such as hexadecane. The fact that environmental isolates show chemotaxis towards contaminant/s present in the site of isolation suggests that chemotaxis might enhance biodegradation by favouring contact between the degrading microorganism and its substrate.

Alkanes↗