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PubMed2006

Ab initio exploration of rearrangement reactions: intramolecular hydrogen scrambling processes in acetone.

The recently developed metadynamics method is applied to the intramolecular hydrogen migration reactions of acetone in the gas phase. Comparison of different sets of collective coordinates allows efficient description of the underlying free energy surface. The simulations yielded numerous reactions: the enol-oxo tautomerism, the decomposition of acetone to various products, and rearrangement reactions. On the basis of the calculated activation barriers it is concluded that the enol-oxo tautomerism is the most frequent intramolecular proton-exchange process the acetone undergoes in the gas phase.

Journal Article↗
PubMed2006

Electronic spectra of uranyl chloride complexes in acetone: a CASSCF/CASPT2 investigation.

A theoretical study is presented of the electronic spectra of the complexes UO(2)Cl(2)ac(4), UO(2)Cl(2)ac(3), [UO(2)Cl(3)ac(2)](-) and [UO(2)Cl(3)ac](-) (ac = acetone) using perturbation theory based on a complete-active-space type wavefunction (CASSCF/CASPT2). Both scalar relativistic effects and spin-orbit coupling were included in the calculations. The calculated excitation energies and oscillator strength values have been compared to the experimental absorption spectrum for uranyl chloride complexes in acetone solution, for chloride-to-uranyl ratios between two and three. The main purpose of this work was to investigate the origin of the remarkable intensity increase observed in the lower part of the experimental absorption spectra, upon addition of chloride to uranyl complexes in acetone. The calculated excitation energies for the different complexes are similar and closely correspond to the experimental data. However, in none of the theoretical spectra, the high intensities observed in the lower part of the experimental spectrum are reproduced.

Journal Article↗
PubMed2005

Isotope effects in dipole-bound anions of acetone.

Precision measurements using the Rydberg charge-exchange and electric field-detachment methods find that the dipole-bound electron affinity (EA) of acetone (C3H6O) is 55+/-10 mueV greater than for deuterated acetone (C3D6O). The result agrees well with a theoretical prediction obtained with high-level electronic-structure and anharmonic vibrational calculations. The dipole moments calculated for the vibrationally averaged structures of C3H6O and C3D6O show that the isotope effect (2% reduction) on the EA of acetone is mainly due to a slight reduction (0.5%) of the average dipole moment upon deuteration.

Journal Article↗
PubMed1985

Modulation of acetone-butanol-ethanol fermentation by carbon monoxide and organic acids.

Metabolic modulation of acetone-butanol-ethanol fermentation by Clostridium acetobutylicum with carbon monoxide (CO) and organic acids is described. CO, which is a known inhibitor of hydrogenase, was found to be effective in the concentration range of dissolved CO corresponding to a CO partial pressure of 0.1 to 0.2 atm. Metabolic modulation by CO was particularly effective when organic acids such as acetic and butyric acids were added to the fermentation as electron sinks. The uptake of organic acids was enhanced, and increases in butyric acid uptake by 50 to 200% over control were observed. Hydrogen production could be reduced by 50% and the ratio of solvents could be controlled by CO modulation and organic acid addition. Acetone production could be eliminated if desired. Butanol yield could be increased by 10 to 15%. Total solvent yield could be increased 1 to 3% and the electron efficiency to acetone-butanol-ethanol solvents could be increased from 73 to 78% for controls to 80 to 85% for CO- and organic acid-modulated fermentations. Based on these results, the dynamic nature of electron flow in this fermentation has been elucidated and mechanisms for metabolic control have been hypothesized.

Journal Article↗
PubMed2004

Rayleigh-calibrated fluorescence quantum yield measurements of acetone and 3-pentanone.

We measured fluorescence quantum yields of acetone and 3-pentanone as a pure gas and with nitrogen diluent at room temperature at 20, 507, and 1013 mbar using 248, 266, and 308 nm excitation by calibrating the optical collection system with Rayleigh scattering from nitrogen. At 20 mbar with 308-nm excitation, the fluorescence quantum yields for acetone and 3-pentanone are 7 +/- 1 x 10(-4) and 1.1 +/- 0.2 x 10(-3), respectively, and each decreases with decreasing excitation wavelength. These directly measured values are significantly lower than earlier ones that were based on a chain of relative measurements. The observed pressure and excitation wavelength dependence is in qualitative agreement with a previously developed fluorescence quantum yield model, but the absolute numbers disagree. Changing acetone's fluorescence rate constant to 3 x 10(5) s(-1) from its previous value of 8 x 10(5) s(-1) resulted in good agreement between our measurements and the model.

Journal Article↗
PubMed2006

[Mechanisms of action of acetonic and hexanic extracts of leaves of Vernonia colorata (Willd.) Drake (Composeae) on blod glucose regulation].

INTRODUCTION: This study aimed to investigate the mechanism of action of acetonic and hexanic extracts of the leaves of Vernonia colorata on blood glucose regulation. MATERIALS AND METHODS: Experiments were performed in normoglycaemic, type 1 and 2 diabetic rats. The effects of acetonic and hexanic extracts on blood glucose were evaluated. The antagonism effect of hexanic extract on the decrease of blood glucose induced with glibenclamide and metformin was also tested. RESULTS: The hexanic extract of the leaves of V. colorata (HELVC) dose dependently increased the blood glucose in normoglycaemic rats. At the dose of 30 and 100 mg/kg, the glycaemia varied from 0.84 +/- 0.02 to 1.11 +/- 0.10 g/l and 0.68 +/- 0.02 to 1.31 +/- 0.30 g/l (p<0.05, n = 5). Such glibenclamide, the acetonic extract of the leaves of V. colorata (AELVC) induced hypoglycaemia in normoglycaemic rats. The HELVC prevents significantly the AELVC and glibenclamide induced hypoglycaemia. The chronic administration of the AELVC and HELVC as well as glibenclamide in type 1 diabetic rats did not change significantly the level of blood glucose. In type 2 diabetic rats, the single dose administration of metformin (300 mg/kg, per os) decreased the glycaemia which is completely prevented by a HELVC pretreatment. CONCLUSION: These results suggest that: i) The respective hypo- and hyperglycaemic effects of AELVC and HELVC require the presence of the pancreatic beta cells. ii) The AELVC would act by a sulfonylurea-like mechanism as glibenclamide to induce an hypoglycaemic effect.

Animals↗
PubMed1969

A controlled field trial to evaluate the protective capacity of a single dose of acetone-killed agar-grown and heat-killed broth-grown typhoid vaccines.

In a strictly controlled field trial among schoolchildren a study was made of the protective capacity of single doses of 2 typhoid vaccines: a heat-killed broth-grown sorbed dried vaccine made in the USSR (vaccine G-66) and an acetone-killed agar-grown dried vaccine (vaccine K-66) made in Yugoslavia. The latter vaccine was supplied by the World Health Organization.A single dose of these preparations exerted a statistically significant protective effect during the first 10 months of observation. The protection afforded by the acetone-killed and heat-killed sorbed vaccines was similar in duration and intensity to that resulting from single doses of other types of typhoid vaccines that had been evaluated earlier in the USSR. The data obtained confirm once again that successful immunization against typhoid is possible with a single dose of vaccine.The absence of any substantial difference in morbidity between the groups concerned indicates that the heat-killed broth-grown and acetone-killed agar-grown vaccines exert a roughly similar protective effect.

Adolescent↗
PubMed1964

PREPARATION OF DRIED ACETONE-INACTIVATED AND HEAT-PHENOL-INACTIVATED TYPHOID VACCINES.

Controlled field trials of two dried inactivated typhoid vaccines have been carried out in British Guiana and Yugoslavia under the sponsorship of the World Health Organization. This paper gives details of the methods of preparation of these vaccines in such a manner as to permit of replication by others.Both vaccines were derived from the Ty 2 strain of Salmonella typhosa. For production of the acetone-inactivated vaccine, a portion of the surface agar growth of the Ty 2 strain was treated with acetone by the Landy method modified so that inactivation and handling were done in liquid suspensions rather than on a filter, and the vaccine was dried in the final containers. For the heat-phenol product, another portion of the same growth was processed by heating, the addition of 0.5% phenol and holding at room temperature for 72 hours followed by freeze-drying in the final containers. These vaccines are designed for use within a few hours of the addition of the reconstituting fluid.

Acetone↗
PubMed2006

Exploitation of the alcohol dehydrogenase-acetone NADP-regeneration system for the enzymatic preparative-scale production of 12-ketochenodeoxycholic acid.

The performance of a new NADP-regeneration system, based on the use of alcohol dehydrogenase (ADH)-acetone, has been investigated for the regioselective oxidation of cholic acid (1) to 12-ketochenodeoxycholic acid (2). Enzymes stabilities and substrate and/or product inhibitory effects under defined synthetic reaction conditions have been evaluated. The optimized system, based on a 4% w/v solution of 1 in a reaction mixture containing 25% v/v acetone, allowed the preparative scale transformation of 1 into 2 with a 92% conversion.

Acetone↗
PubMedDate not supplied

The dermal bioavailability of radiolabelled benzo[a]pyrene from acetone or from oils of differing viscosity, assessed by DNA and protein binding.

Tritium-labelled benzo[a]pyrene ([3H]BaP) was applied to mouse skin in acetone or mineral oils of differing viscosity. Epidermal DNA and protein were extracted after 24 or 48 h and the degree of adduct formation determined by the radioactivity present. When [3H]BaP was applied in acetone, the degree of DNA and protein binding was around 15-20 times greater than that observed when a low-viscosity oil was used as a vehicle. When applied in oils of differing viscosity, however, only a twofold difference was seen across the whole viscosity range (13.5 cSt* at 40 degrees C to 1665 cSt at 60 degrees C). From measurements made of urine and faecal radioactivity and from small-scale investigations using other routes of administration, it was clear that the grooming activity of the animals had a marked effect on skin absorption and macromolecular binding. It is possible that greater grooming activity with low-viscosity oils may explain why oil viscosity did not have a greater effect on binding levels, but further studies are needed to investigate this. These findings may have important implications in the interpretation of long-term skin painting studies and may assist in the interpretation of analytical data and short-term biological assays.

Acetone↗
PubMed1993

Time-dependent effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on serum and urine levels of malondialdehyde, formaldehyde, acetaldehyde, and acetone in rats.

The ability of TCDD to produce lipid mobilization and alter lipid metabolism is well known. Previous studies have indicated that TCDD induces an oxidative stress and enhances lipid peroxidation. However, the products resulting from altered lipid metabolism in response to TCDD have not been studied. We have examined the time-dependent changes in serum and urine levels of malondialdehyde, formaldehyde, acetaldehyde, and acetone in response to a single oral 50 micrograms/kg dose of TCDD in rats. The changes in these four metabolic products were quantitated by high-pressure liquid chromatography (HPLC). The effects of TCDD were compared in ad libitum-fed control animals and pair-fed animals. Serum and urine levels of the four metabolites were assayed on Days 0, 3, 6, 9, and 12. Following TCDD administration, significant increases in the four metabolites present in serum and urine were observed at all time points. For example, on Day 6 post-treatment malondialdehyde, formaldehyde, acetaldehyde, and acetone increased approximately 1.8-, 1.4-, 2.0-, and 3.0-fold in serum, respectively, and 1.3-, 1.4-, 1.6-, and 2.0-fold in urine, respectively, relative to pair-fed control animals. Increases in the serum and urine levels of the four metabolites were significantly greater for TCDD animals than for pair-fed control animals at most time points. When the serum levels of malondialdehyde as determined by HPLC were compared with the results obtained by the thiobarbituric acid (TBA) colorimetric method, similar time courses were observed although higher results were obtained for the less specific TBA method. The results clearly demonstrate that TCDD causes markedly elevated serum and urine levels of four specific products associated with lipid metabolism.

Acetaldehyde↗
PubMed1996

Relationship between acetone exposure concentration and health effects in acetate fiber plant workers.

In order to clarify the effects of acetone (AC) exposure on health, a cross-sectional study was carried out in 110 male AC-exposed and 67 male nonexposed shift workers. The AC workers ranged in age from 18.7 to 56.8 years (mean: 37.6 years) and in length of AC exposure from 0.5 to 34.3 years (mean: 14.9 years). The nonexposed workers ranged in age from 20.7 to 57.5 years (mean: 41.9 years). AC exposure levels assessed by personal passive monitors and biological monitoring indices measured at the end of the workshift were 19.6-1018 ppm in the breathing zone (AC-E, mean: 364 ppm), 2.5-422 ppm in alveolar air (AC-A, mean: 97.3 ppm) 4-220 mg/l in blood (AC-B, mean 66.0 ppm), and 0.75-170 mg/l in urine (AC-U, mean: 37.8 mg/l). Symptoms at the end of the workshift with good exposure-response relationships were eye irritation, tearing, and acetone odor, and symptoms within the previous 6 months with good exposure-response relationships were heavy, vague, or faint feeling in the head, nausea, loss of weight, and slow healing of an external wound. In the 30-44 year age range, simple reaction time and digit span scores in a short computerized neuro-behavioral test battery were significantly lower in AC workers, but exposure-response relationships were not clear. Manifest Anxiety Scale scores, Self-rating Depression Scale scores, R-R interval variation on the ECG, hematological examinations, serum biochemistry examinations for liver function, and phagocytic activity of peripheral neutrophils did not show any AC-related differences between the two groups. In view of the reported findings, the current occupational exposure limit of 750 ppm recommended by many governmental and academic associations seems to be too high to prevent the health effects of AC observed in this study.

Acetone↗
PubMed1979

Effect of acetone on VLDL secretion by the isolated rat liver.

High acetone levels occur in uncontrolled diabetes and after isopropanol administration to rats. In both conditions, very low density lipoproteins (VLDL) secretion is depressed. Acetone, hoever, failed to affect the VLDL secretion rate by the isolated perfused rat liver, suggesting that this metabolite is not involved in impaired VLDL production in diabetes and after isopropanol administration.

Acetone↗
PubMed1985

Detection and clinical significance of acetone-insoluble liver cell membrane antigen in sera of patients with chronic active liver diseases.

An enzyme-linked immunosorbent assay was developed to detect insoluble liver cell membrane antigen (LMAg) which gives rise to serum LMA (anti-LM) in HBsAg-negative patients. The optical density (OD) ratio of the average LMAg level of normal subjects was less than 1.2. In HBsAg-positive cases, high LMAg levels (OD ratio greater than 2.4) were noted in 8 of 8 patients with acute hepatitis (AH), 3 of 8 with chronic persistent hepatitis (CPH), 5 of 10 with moderate chronic aggressive hepatitis (CAH), 7 of 10 severe CAH and 4 of 8 with liver cirrhosis (LC). In HBsAg-negative cases, however, high LMAg levels were noted in only 6 of 8 patients with AH, 1 of 10 with CPH, 1 of 10 with moderate CAH, 1 of of 10 with severe CAH, 0 of 8 with LC, 0 of 8 with fatty liver and 5 of 10 with alcoholic hepatitis. In micro-immunodiffusion experiments, intensively absorbed rabbit anti-rat LM precipitated two organ-specific components of rat liver homogenate, one of which was identical to liver specific protein (LSP). In immunohistochemical demonstrations of LMAg and LSP, anti-LM, prepared from the serum of a HBsAg-negative CAH patient, bound to both human and rat acetone-fixed liver cell membranes, but not to those of human or rat kidneys. Absorbed rabbit anti-rat LM also bound to liver cell membranes, but absorbed anti-rat LSP lacked organ-specificity when assayed with the immunofluorescence technique using acetone-fixed liver sections. In conclusion, the appearance of serum LMAg was associated with high-SGPT patients and HBsAg-positive CAH patients.

Acetone↗
PubMed2003

Acetone butanol ethanol (ABE) production from concentrated substrate: reduction in substrate inhibition by fed-batch technique and product inhibition by gas stripping.

Acetone butanol ethanol (ABE) was produced in an integrated fed-batch fermentation-gas stripping product-recovery system using Clostridium beijerinckii BA101, with H(2) and CO(2) as the carrier gases. This technique was applied in order to eliminate the substrate and product inhibition that normally restricts ABE production and sugar utilization to less than 20 g l(-1) and 60 g l(-1), respectively. In the integrated fed-batch fermentation and product recovery system, solvent productivities were improved to 400% of the control batch fermentation productivities. In a control batch reactor, the culture used 45.4 g glucose l(-1) and produced 17.6 g total solvents l(-1) (yield 0.39 g g(-1), productivity 0.29 g l(-1) h(-1)). Using the integrated fermentation-gas stripping product-recovery system with CO(2) and H(2) as carrier gases, we carried out fed-batch fermentation experiments and measured various characteristics of the fermentation, including ABE production, selectivity, yield and productivity. The fed-batch reactor was operated for 201 h. At the end of the fermentation, an unusually high concentration of total acids (8.5 g l(-1)) was observed. A total of 500 g glucose was used to produce 232.8 g solvents (77.7 g acetone, 151.7 g butanol, 3.4 g ethanol) in 1 l culture broth. The average solvent yield and productivity were 0.47 g g(-1) and 1.16 g l(-1) h(-1), respectively.

Acetone↗
PubMed2001

Molecular weight dependence of polyethylene glycol penetration across acetone-disrupted permeability barrier.

Previous studies have demonstrated that permeability barrier disruption by acetone treatment significantly enhances skin permeability to both hydrophilic and amphipathic compounds, but not to highly lipophilic compounds. The purpose of the present study was to investigate the dependence of permeability on molecular weight (MW) in acetone-disrupted hairless mouse skin in contrast to normal skin. Penetration of polyethylene glycol (PEG) 300, 600, and 1,000 over 12 h was measured using diffusion cells. High-performance liquid chromatographic methods with refractive index detection were used to separate and quantitate the individual oligomeric species in the PEG samples. Percutaneous penetration of PEGs exhibited slightly steeper MW dependency at a transepidermal water loss (TEWL) of 30-41 g/m2 per h in comparison with TEWLs of 0-10 (control skin), 10-20, and 20-30 g/m2 per h, with a higher percentage of smaller oligomer PEGs penetrating than larger ones. Increasing the TEWL of the skin increased the penetration of all the PEG oligomers, and the degree of the enhancement relative to penetration through control skin increased with MW and was maximal for oligomers with a MW ranging from 326 to 414 Da. Within the limit of quantitation of the assay, the MW cut-off for PEG penetration across mouse skin with TEWLs of 0-10, 10-20, and 20-30 g/m2 per h was 414, 590, and 942 Da, respectively, while all the measurable oligomers up to MW 1,074 Da were able to penetrate skin with TEWLs in the range 30-41 g/m2 per h. The results suggest that not only higher amounts but also more varieties of chemicals may penetrate skin with a compromised barrier than normal skin, implying a higher risk of intoxication and hypersensitization by environmental agents through diseased skin with impaired barrier function.

Acetone↗
PubMed1984

Colorimetric method for the determination of ketoses using phenol-acetone-boric acid reagent (PABR).

A purplish pink color developed when ketose solution (100 microliters) was mixed with phenol-acetone-boric acid reagent (0.5 ml 5% phenol, 2% acetone, 4% boric acid) and then treated with 96% sulfuric acid (1.4 ml). The absorbance of the reaction mixture was measured at 568 nm after 60 min at 37 degrees C. This method allowed the simple determination of 3-50 nmol of D-fructose with coefficient of variation 7.8% for 3 nmol and 2.8% for 50 nmol. Carbohydrates other then ketoses did not interfere with this reaction. The influence of various chemicals on the colorimetric reaction and applicability of the method for determination of ketoses in natural products are presented.

Acetone↗
PubMed1986

Acetone-inducible cytochrome P-450: purification, catalytic activity, and interaction with cytochrome b5.

A procedure was developed for the purification of an acetone-inducible form of cytochrome P-450 (P-450ac) to electrophoretical homogeneity from liver microsomes of acetone-treated rats. The P-450ac preparation containing 16.0 to 16.5 nmol P-450/mg protein moved as a single protein band with an estimated molecular weight of 52,000 upon gel electrophoresis in the presence of sodium dodecyl sulfate. The ferric P-450ac showed an absorption maximum at 394 nm at 25 degrees C, suggesting that it exists mainly in the high-spin form. It also existed in the low-spin form, especially at lower temperatures, as indicated by the absorption maximum in the 412-nm region. Upon reconstitution with NADPH: cytochrome P-450 reductase and phospholipid, P-450ac efficiently catalyzed both the demethylation and denitrosation of N-nitrosodimethylamine (NDMA) showing Vmax values of 23.8 and 2.3 nmol min-1 nmol P-450-1, respectively. The catalytic activity of P-450ac was greatly affected by cytochrome b5 which decreased the Km values of these reactions by a factor of 10 and increased the Vmax values. Cytochrome b5 appeared to interact with P-450 at a molar ratio of 1:1 and an intact cytochrome b5 structure was required for such interaction. Among the substrates studied, the demethylation of NDMA was affected the most by cytochrome b5 and showed the highest rate. P-450ac also catalyzed the oxygenation of N-nitrosomethylethylamine and aniline and the activity was enhanced slightly by cytochrome b5. Cytochrome b5 did not enhance the P-450ac-catalyzed metabolism of other drug substrates such as benzphetamine, aminopyrine, and ethylmorphine. P-450ac appeared to be similar in property to the previously studied rat P-450et (ethanol-inducible), rat P-450j (isoniazid-inducible), and rabbit P-450LM3a (ethanol-inducible). These P-450 species represent a new class of P-450 isozymes that are important in the metabolism of many endobiotics and xenobiotics.

Acetone↗