Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Volatilization”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,225 records · Page 68Linked to original sources
PubMed1997

Identification of cheese-associated fungi using selected ion monitoring of volatile terpenes.

The cheese-associated fungi Penicillium commune, P. roqueforti, P.solitum, P. discolor and Aspergillus versicolor have been investigated for production of volatile terpenes for chemical identification, when grown on yeast extract agar. Volatiles were collected by headspace solid-phase microextraction. Selected ion monitoring of four to seven of the most characteristic ions of mainly sesquiterpenes made it possible to identify the fungi to species level within 2 d. In a mixed culture of P. roqueforti and P. commune, inoculated in a ratio of 1000:1, volatiles from both fungi could be detected within 3 d, making identification possible.

Aspergillus↗
PubMed2001

Intragastric volatile N-nitrosamines, nitrite, pH, and Helicobacter pylori during long-term treatment with omeprazole.

BACKGROUND & AIMS: This study evaluated the effect of long-term gastric acid suppressive therapy with omeprazole on intragastric levels of carcinogenic N-nitrosamines and related parameters. METHODS: Forty-five patients on long-term omeprazole medication (mean, 35 months) and 13 healthy subjects without medication participated. Volatile N-nitrosamines were determined in gastric juice and urine. Intragastric pH, nitrite, nitrate, and H. pylori status were determined. DNA isolated from gastric biopsy specimens was analyzed for precarcinogenic alkyl-DNA adducts. RESULTS: The intragastric pH in patients was significantly higher compared with controls (P = 0.0001). Gastric nitrite levels in patients were nonsignificantly higher. There was no difference in total levels of intragastric volatile N-nitrosamines between patients and controls, however, urinary N-nitrosodimethylamine excretion was higher in patients (P = 0.001). On omeprazole, Helicobacter pylori-positive vs. -negative patients had a nonsignificantly higher intragastric nitrite level and higher urinary N-nitrosodimethylamine excretion. No alkyl-DNA adducts could be detected in gastric epithelium. CONCLUSIONS: Increased intragastric pH caused by long-term treatment with omeprazole does not result in increased intragastric levels of nitrite and volatile N-nitrosamines. The significantly higher urinary N-nitrosamine excretion implies the risk of increased endogenous formation of N-nitrosamines during long-term omeprazole treatment. This risk may be higher in H. pylori-positive patients.

Adult↗
PubMed2006

The leaf volatile constituents of Isatis tinctoria by Solid-Phase Microextraction and Gas chromatography/Mass Spectrometry.

The leaf volatile constituents of Isatis tinctoria L. (Brassicaceae) have been studied by Solid-Phase Microextraction and Gas chromatography/Mass Spectrometry (SPME/GC-MS). Seventy components were fully characterized by mass spectra, linear retention indices, and injection of standards; the average composition (ppm) as single components and classes of substances is reported. Aliphatic hydrocarbons, acids, alcohols, aldehydes and esters, aromatic aldehydes, esters and ethers, furans, isothiocyanates and thiocyanates, sulfurated compounds, nitriles, terpenes and sesquiterpenes were identified. Leaf volatiles in Isatis tinctoria L. were characterized by a high amount of isothiocyanates which accounted for about 40 % of the total volatile fraction. Isothiocyanates are important and characteristic flavour compounds in Brassica vegetables and the cancer chemo-protective attributes are recently responsible for their growing interest.

Gas Chromatography-Mass Spectrometry↗
PubMed1993

[Pharmacodynamic effects of the phosphodiesterase inhibitor enoximone during exposure to the volatile anesthetics halothane and isoflurane in coronary surgery patients].

AIM OF THE STUDY: We investigated the pharmacodynamic effects of the phosphodiesterae inhibitor enoximone in the presence of halothane and isoflurane in 20 patients, ASA class III, aged 45-75 years, undergoing coronary artery bypass grafting. The study was approved by the local Medical Ethics Committee and patients' informed written consent was obtained. METHODS: After induction of anaesthesia (midazolam, fentanyl, etomidate and pancuronium) all patients received either halothane 1 MAC (group I, n = 10) or isoflurane 1 MAC (group II, n = 10), followed 20 min later by enoximone 0.5 mg/kg. Haemodynamic variables were measured and blood samples (arterial, mixed venous) were obtained before the administration of the volatile anaesthetics (control, t0), immediately (t1) and 5 (t2) min after steady state conditions with halothane or isoflurane, as verified by the end-expiratory concentration and 5 (t3) and 10 (t4) min after the injection of enoximone. Heart rate (HR), mean arterial pressure (MAP), mean pulmonary artery pressure, pulmonary capillary wedge pressure and right atrial pressure were recorded. Cardiac (CI) and stroke volume indices, systemic (SVR) and pulmonary vascular resistance, oxygen availability (AO2) oxygen consumption and oxygen extraction rate were calculated using standard formulae. RESULTS: In both groups HR remained essentially unchanged throughout the investigation period. MAP decreased significantly in both groups under steady state conditions with the volatile anaesthetics (group I: 19%; group II: 30%) but remained unchanged after subsequent injection of enoximone. After administration of halothane SVR remained essentially unchanged, whereas isoflurane decreased SVR significantly by 20%. After enoximone, there was a significant decrease in SVR in both groups (group I: 26%; group II: 25% compared with the values obtained after halothane and isoflurane respectively). Halothane and isoflurane decreased CI significantly and to a similar degree (group I: 17%; group II: 17%). After the injection of enoximone CI increased significantly and reached control values in both groups. AO2 decreased significantly after administration of the volatile anaesthetics (group I: 19%; group II: 21%) and increased significantly after administration of enoximone, returning to control values. Halothane (7%) and isoflurane (13%) produced a significant increase in oxygen extraction. After bolus injection of enoximone oxygen extraction decreased significantly and returned to control value in group II. In group I enoximone decreased oxygen extraction significantly compared with control. CONCLUSION: Our results suggest that in the presence of halothane or isoflurane the phosphodiesterase inhibitor enoximone produces a comparable increase in cardiac output and decrease in systemic vascular resistance in patients with coronary artery disease.

Aged↗
PubMed2005

Relativistic effects on the electronic structure and volatility of group-8 tetroxides MO4, where M=Ru, Os, and element 108, Hs.

The influence of relativistic effects on properties and volatility of the group-8 tetroxides MO4, where M=Ru, Os, and element 108, Hs, was studied on the basis of results of the fully relativistic (four component) and nonrelativistic density functional theory calculations. Relativistic effects were shown to increase bond strengths and decrease bond lengths in these molecules. They are responsible for a decrease in molecular polarizabilities and an increase in ionization potentials. The effects are much stronger in HsO4 than in the lighter congeners. Relativistic effects were also shown to slightly decrease dispersion interaction energies of RuO4, OsO4, and HsO4 with an inert (quartz or silicon nitride) surface, i.e., they increase volatility of these compounds as studied in the "one-atom-at-a-time" gas-phase chromatography experiments. They do, however, not influence the trend in group 8: both relativistically and nonrelativistically, volatility should change as RuO4<OsO4<HsO4. The reason for that is identical trends in the relativistic and nonrelativistic space distributions of the valence d electrons.

Journal Article↗
PubMed2005

Scaling and memory in volatility return intervals in financial markets.

For both stock and currency markets, we study the return intervals tau between the daily volatilities of the price changes that are above a certain threshold q. We find that the distribution function Pq(tau) scales with the mean return interval tau as Pq(tau)=tau(-1)f(tau/tau). The scaling function fx is similar in form for all seven stocks and for all seven currency databases analyzed, and fx is consistent with a power-law form, fx approximately x(-gamma) with gamma approximately 2. We also quantify how the conditional distribution Pq(tau/tau0) depends on the previous return interval tau0 and find that small (or large) return intervals are more likely to be followed by small (or large) return intervals. This "clustering" of the volatility return intervals is a previously unrecognized phenomenon that we relate to the long-term correlations known to be present in the volatility.

Journal Article↗
PubMed1997

Volatile signals of the major histocompatibility complex in male mouse urine.

Variation in the genes of the major histocompatibility complex (MHC) contributes to unique individual odors (odortypes) in mice, as demonstrated by the ability of trained mice in a Y-maze olfactometer to discriminate nearly identical inbred mice that differ genetically only at the MHC (MHC congenic mice), while they cannot distinguish genetically identical inbred mice. Similar distinctions are possible with urine, a substance that is involved in many facets of mouse chemical communication. This paper reports results supporting the hypothesis that the MHC-determined urinary odor is composed of a mixture of volatile carboxylic acids occurring in relative concentrations that are characteristic of the odortype. Y-maze behavioral testing of urine fractions from anion exchange chromatography indicates that volatile acids are necessary and sufficient to convey MHC odortype information. Diethyl ether extracts, which are expected to contain the more volatile, less polar organic acids, were also discriminable in the Y-maze olfactometer. Ether extracts of 12 different urine samples from each of two panels of MHC congenic mice were analyzed by gas chromatography. No compounds unique to urine of either genotype were detected, but compounds did appear to occur in characteristic ratios in most of the samples of each type. Nonparametric statistical analysis of the gas chromatographic data showed that eight of the peaks occurred in significantly different relative concentrations in the congenic samples. One of the peaks was shown to represent phenylacetic acid, which has implications for the mechanism of the MHC specification of odortype.

Animals↗
PubMed1998

Concerted biosynthesis of an insect elicitor of plant volatiles.

A variety of agricultural plant species, including corn, respond to insect herbivore damage by releasing large quantities of volatile compounds and, as a result, become highly attractive to parasitic wasps that attack the herbivores. An elicitor of plant volatiles, N-(17-hydroxylinolenoyl)-L-glutamine, named volicitin and isolated from beet armyworm caterpillars, is a key component in plant recognition of damage from insect herbivory. Chemical analysis of the oral secretion from beet armyworms that have fed on 13C-labeled corn seedlings established that the fatty acid portion of volicitin is plant derived whereas the 17-hydroxylation reaction and the conjugation with glutamine are carried out by the caterpillar by using glutamine of insect origin. Ironically, these insect-catalyzed chemical modifications to linolenic acid are critical for the biological activity that triggers the release of plant volatiles, which in turn attract natural enemies of the caterpillar.

Journal Article↗
PubMedDate not supplied

Chromosome abnormalities and sister chromatid exchanges in children with acute intoxication due to inhalation of volatile substances.

Deliberate inhalation of volatile substances is a common and harmful practice among young persons worldwide. Recently, we described chromosome damage in children who chronically inhale volatile agents. Clinical and cytogenetic studies were performed for 15 "sniffing" children (13 boys and 2 girls), the purpose of which was to define the chromosomal effect of the acute intoxication. A significant increase in the rate of chromosome abnormalities and in the frequency of sister chromatid exchanges (SCEs) was found in sniffers vs. controls. The values were also higher in children who were acutely intoxicated than in those who chronically inhaled volatile agents. Clinical, socioeconomic, and cytogenetic findings are also discussed.

Adolescent↗
PubMedDate not supplied

A basis for estimation of consumption: literature values for selected food volatiles. Part I.

This paper is a compilation of quantitative data available on volatile compounds reported so far in 18 food items including some legume, cereals, grapes and cheeses as well as crab, lobster, cocoa and chocolate. No publications reporting quantitative data were found for five of these 18 food products, i.e. sultana grape, broad beans, cassava, oat and rye. About 440 volatile compounds have been assayed globally in the other 13 food products and more than 50% of them were found in grape or in grape juice. Levels of these volatile compounds in the selected foods were generally in the ppb range and less often in the low ppm range. Very high levels were found for some carboxylic acids in cheeses and cocoa and for some alcohols and acids as well as for ethyl acetate in grape juice.

Diet↗
PubMedDate not supplied

Volatile nitrosamines in microwave-cooked bacon.

Bacon was analysed for volatile nitrosamines after microwave cooking, and the results were compared with those obtained after frying bacon in a pan. Microwave cooking gave statistically significantly lower levels of all three volatile nitrosamines detected in the bacon. NPYR was found in all 20 samples fried in a pan, but in only five microwave-cooked samples. The average volatile nitrosamine levels (micrograms/kg) in microwave-cooked bacon and pan-fried bacon were: NDMA, 0.3 and 1.2; NPIP, 0.04 and 0.2; NPYR, 0.1 and 4.5.

Animals↗
PubMed1999

Determination of volatile organohalogen compounds in human urine.

A variant of thin layer headspace (TLHS) analysis with autogenous generation of the liquid sorbent was applied for the determination of volatile organohalogen compounds in urine. The analytes were isolated from the matrix at an elevated temperature in a TLHS column. They were then transported by a stream of purified air to a second TLHS column kept at sub-ambient temperature. Water vapor contained in the air condensed in the second column together with the analytes. The effluent from the second column was analyzed by direct aqueous injection gas chromatography with electron capture detection (DAI-GC-ECD). It has been established that the complex urine matrix did not affect the results at a 95% confidence level. Volatile organohalogen compounds were detected in urine of employees of a chemical laboratory where halogenated solvents were used. The urine of people who were not exposed contained insignificant or undetectable levels of these compounds. Urine levels of target analytes were the higher, the longer a person was exposed to them. The results obtained confirm that the urinary system participates in excretion of volatile organohalogen compounds.

Air Pollutants↗
PubMed1996

Air quality in an animal facility: particulates, ammonia, and volatile organic compounds.

Concentrations of ammonia, volatile organic compounds, particles, and mouse allergen were measured in an animal facility. Ammonia concentrations averaged less than 1 ppm, below any health-based standards. The concentrations of volatile organic compounds were in the 5-15 micrograms/m3 range. Among the volatile organic compounds found, only the terpenes a-pinene and a-terpinol (which may be derived from the pine shavings used as bedding) were consistently present in concentrations greater than outdoor air. The primary air contaminant present at concentrations high enough to be of known physiological significance was the mouse allergen, Mus ml. To determine which activities in an animal room generated the highest concentrations of airborne Mus ml, a monitor that counted particles continuously was used. The particle counts were correlated with allergen levels in the worker's breathing zone (r50.83,p,0.05). Thus, a particle counter can be used effectively in an animal facility to identify specific activities that generate high levels of both particles and allergen. Such activities included changing mice from soiled to clean cages, cleaning floors, and changing foam inserts in pressurized individually ventilated cages. To reduce exposure to allergen during cage changing, which is the major activity for an animal caretaker, a capture-type ventilated changing table was designed and tested. Use of such a table reduced exposure to allergen in the worker's breathing zone from 4.961.1 to 2.160.3 ng Mus ml/m3, a level comparable to background levels.

Air Pollutants, Occupational↗
PubMed2004

Volatile metabolic monitoring of glycemic status in diabetes using electronic olfaction.

The increased incidence of Type I and Type II diabetes among adults and adolescents is a growing public health concern worldwide. The primary objective of diabetes mellitus management involves keeping glycemia levels within the euglycemic range to prevent a variety of serious health complications. Unfortunately, daily self-monitoring is both a requirement and a problem for many patients with diabetes, particularly children and adolescents. Studies have shown that as many as 43% of adolescents and 30% of children (<14 years old) regularly forget to use glycemic tests and are significantly poorer at recognizing and reporting symptoms and signs of hypoglycemia/hyperglycemia. For this reason, methods for noninvasive, continuous monitoring that can signal glycemic status to a parent, teacher, or other caregiver would improve the care and management of symptoms of diabetes among these individuals. The goal of this review is to describe and evaluate electronic olfaction technology ("electronic nose") for monitoring the presence and levels of volatile chemicals from human body and breath that can be used to evaluate status of diabetes. The review is organized in four sections. The first section reviews the chemistry of the volatile signals that are produced by the body that are indicative of metabolic status. The second section provides an overview of novel sensor technology, e.g., "electronic olfaction," that mimics the biological olfactory system and can be used to monitor and identify complex plumes of volatiles that are signatures of metabolic states. The third section reviews studies that have employed electronic "nose" technology for diagnosis and monitoring of diabetes via urine and breath, and the final section discusses needed future directions for the development of olfactory-based metabolic monitoring, particularly among noncompliant populations.

Adolescent↗
PubMed2004

Cardiac preconditioning by volatile anesthetic agents: a defining role for altered mitochondrial bioenergetics.

Volatile anesthetic agents, such as halothane, isoflurane, and sevoflurane, are the drugs most commonly used to maintain the state of general anesthesia. They have long been known to provide some protection against the effects of cardiac ischemia and reperfusion. Several mechanisms likely contribute to this cardioprotection, including coronary vasodilation, reduced contractility with corresponding decreased metabolic demand, and a direct effect to decrease myocardial Ca(2+) entry through L-type Ca(2+) channels. Recently, a memory phase to cardioprotection has been observed by these agents, which is inhibited by ATP-sensitive potassium channel inhibition. These features suggest a pathway that shares components with those required for ischemic preconditioning, despite the remarkable differences between these two stimuli, and the term anesthetic preconditioning (APC) has been adopted. Scavengers of reactive oxygen species (ROS) abrogate APC, suggesting an effect of anesthetic agents to cause ROS formation. Such an effect has recently been directly demonstrated. The mechanism by which these drugs induce ROS formation is unclear. However, direct inhibition of mitochondrial electron transport system enzymes, and altered mitochondrial bioeneregtics in hearts preconditioned by volatile anesthetics, strongly implicate the mitochondria as the target for these effects. Furthermore, decreased mitochondrial ROS formation during ischemia and reperfusion in hearts preconditioned by volatile anesthetics might underlie the improved postischemic structure and function. APC presents a safe mode to apply preconditioning to human hearts. This review summarizes the major developments in a field that is exciting to clinicians and basic scientists alike.

Anesthetics, Inhalation↗
PubMed1989

Effects of nitrous oxide and volatile anaesthetics on cerebral blood flow.

Nitrous oxide and halogenated anaesthetic agents are often administered concurrently during neuroanaesthesia. To assess the interactive effects of these agents on cerebral blood flow (CBF), we have measured CBF by 14C-iodoantipyrine autoradiography, in normocapnic rats receiving either 0.5 or 1.0 MAC of volatile agent alone (halothane or isoflurane) or 0.5 MAC of volatile agent + 0.5 MAC nitrous oxide. CBF (global and regional) was significantly greater at 1.0 MAC compared with 0.5 MAC, regardless of how 1.0 MAC was achieved (agent alone or agent + nitrous oxide) (P less than 0.05). The addition of 0.5 MAC nitrous oxide to 0.5 MAC halothane resulted in flows similar to those produced by 1.0 MAC halothane alone. In contrast, the addition of nitrous oxide to 0.5 MAC isoflurane resulted in flow values significantly greater than those measured during 1.0 MAC isoflurane alone. We conclude that the use of nitrous oxide, as opposed to an increased dose of volatile agent, has no advantage in respect of minimizing anaesthetic-induced increases in cerebral blood flow.

Anesthesia, Inhalation↗
PubMed1992

Effects of halothane and other volatile anaesthetics on protein synthesis and secretion in guinea pig liver slices.

We have investigated the effect of volatile anaesthetics on protein synthesis and secretion in Hartley male guinea pig liver slices. The slices (250-300 microns thick) were incubated in sealed roller vials containing Krebs-Henseleit buffer at 37 degrees C under 95% oxygen. Volatile anaesthetics were vaporized in the vials to produce constant concentrations in the medium. Halothane 1-2.1 mmol litre-1 produced a concentration-related decrease in protein synthesis (3H-leucine incorporation) and secretion. Deuterated halothane (d-halothane), which is less biotransformed, was less inhibiting than halothane: uptake of the 3H-leucine was not affected but its incorporation into the nascent peptide was inhibited. Enflurane 2.2 mmol litre-1, isoflurane 2.2 mmol litre-1 and sevoflurane 2.1 mmol litre-1 also inhibited protein synthesis, but to a lesser extent than halothane and d-halothane. We conclude that alterations in protein synthesis and secretion are an early and sensitive indicator of cellular injury by volatile anaesthetics in liver slices.

Anesthetics↗
PubMed1995

Effect of different volatile anaesthetics on suxamethonium-induced jaw muscle contracture in rats.

Previous work has demonstrated that the interaction of hyperthermia and halothane may greatly increase the jaw muscle contracture produced by suxamethonium. We have compared the interaction of temperature and suxamethonium in the presence of halothane with the suxamethonium/temperature interaction of two other volatile anaesthetics, isoflurane and desflurane. Rats were anaesthetized with 1.35 MAC of halothane, isoflurane or desflurane. The jaw area was heated to 36-41 degrees C by a heating lamp while rectal temperature was maintained at 37 degrees C. Isometric tension was recorded from the jaw muscles. Suxamethonium 750 micrograms kg-1 i.v. induced a transient jaw muscle contracture (JMC) during halothane, isoflurane and desflurane anaesthesia. JMC exhibited significant dependence on jaw muscle temperature with all three volatile anaesthetics. Increasing the temperature of the jaw area from 37 degrees C to 41 degrees C increased JMC 8.7-fold with halothane, 8.8-fold with isoflurane and 3.1-fold with desflurane. The difference between halothane and desflurane was significant. While suxamethonium-induced JMC was dependent on temperature for all three volatile anaesthetic, the temperature dependence appeared to be less with desflurane.

Anesthetics↗