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PubMed1984

The in vivo incorporation of acetate into different non-saponifiable lipids by neonatal chick tissues.

The in vivo incorporation of [l-14C]acetate into non-saponifiable lipids was higher in neonatal chick liver than in intestinal mucosa, brain and kidneys, and proportional to the amount of substrate injected (2-20 mumole). 14CO2 expired in the breath was also proportional to the dose of acetate. Radioactivity from [l-14C]acetate accumulated by liver was maximal 30 min after the injection of acetate and decreased afterwards. Acetate was mainly incorporated into cholesterol by all the tissues assayed, although small percentages of lanosterol and squalene were obtained in liver. In this tissue, distribution of radioactivity was practically independent from the dose of substrate injected while in intestinal mucosa, brain and kidneys the percentage of cholesterol increased with this dose. The time course of the in vivo formation of different non-saponifiable lipids by neonatal chick tissues was also studied. More than 90% of radioactivity in this fraction obtained 15 min after the acetate injection was recovered as cholesterol in liver and kidneys, while in brain and intestinal mucosa this percentage was about 50% at this time, increasing afterwards. A high percentage of lanosterol was found in brain and intestinal mucosa 15 min after the injection of acetate.

Acetates↗
PubMed1990

Postsynaptic fall in intracellular pH and increase in surface pH caused by efflux of formate and acetate anions through GABA-gated channels in crayfish muscle fibres.

H(+)-selective microelectrodes and a two- or three-microelectrode voltage clamp were used to examine the influence of weak-acid, carboxylate anions on the actions of GABA on postsynaptic intracellular pH, surface pH and on membrane potential in fibres of the crayfish leg opener muscle. Substitution of 30 mM Cl- by formate or acetate promoted a GABA-induced decrease in intracellular pH, which was coupled to an increase in surface pH and to a depolarization. Such effects were not seen in the presence of an equivalent amount of lactate, methanesulphonate or glucuronate. Both the GABA-induced depolarization and the fall in internal pH promoted by formate and acetate were blocked by picrotoxin, and the fall in pH was reversibly inhibited by a K(+)-induced depolarization. The rate of the fall in intracellular pH produced by GABA (0.2 mM) was about 0.02 pH units/min in the presence of formate and 0.03 pH units/min in the presence of acetate. Under steady-state conditions, both 30 mM formate and acetate (but not lactate) induced a positive shift in the reversal potential of GABA-activated current, which was accounted for by a relative permeability vs Cl- of formate and acetate of 0.5 and 0.15, respectively. The conductance sequence of the anions was identical to the permeability sequence, i.e. Cl- greater than formate greater than acetate greater than lactate approximately equal to 0. This sequence is strictly correlated to the Stokes diameter of the anions. The relative permeabilities of the anions indicate that the effective diameter of the GABA-gated channel is about 0.5 nm. The fact that the GABA-induced acidosis was slower in the presence of formate than in the presence of acetate suggests that, in the former case, the rate-limiting step in the fall in internal pH is the entry of non-dissociated formic acid. All the above results are consistent with a scheme where GABA induces a channel-mediated efflux of permeant weak-acid anions, which gives rise to an inward (depolarizing) current and to an intracellular acidosis. A comparison of the permeability properties of crayfish and vertebrate GABA-gated channels suggests that effects similar to those seen in this work are likely to occur in mammalian and other vertebrate neurons in the presence of permeant weak-acid anions.

Acetates↗
PubMed2006

Effect of hypoxia on the uptake of [methyl-3H]choline, [1-14C] acetate and [18F]FDG in cultured prostate cancer cells.

INTRODUCTION: Choline, acetate and glucose ([2-(18)F]fluoro-2-deoxyglucose, [(18)F]FDG) analogs are under investigation as positron emission tomography (PET) tracers for the imaging of prostate cancer; however, their response to tumor hypoxia has not been clarified. METHODS: The uptake of [methyl-(3)H]choline, [1-(14)C]acetate and [(18)F]FDG was monitored in androgen-independent PC-3 cells and androgen-sensitive LNCaP cells under aerobic or anoxic conditions. The effect of androgen depletion was also examined. RESULTS: PC-3 cells exhibited aerobic choline and acetate uptake five to six times higher than FDG uptake, whereas LNCaP cells showed choline uptake 2.2-fold higher than acetate uptake and 10-fold higher than FDG uptake. After 4 h of anoxia, PC-3 cells showed an 85% increase in FDG uptake, a 15% decrease in choline uptake and a 36% increase in acetate uptake, whereas LNCaP cells showed a 212% increase in FDG uptake, a 28% decrease in choline uptake and no change in acetate uptake. Androgen depletion resulted in a marked decrease in the uptake of all tracers in LNCaP cells but no changes in PC-3 cells. CONCLUSION: In aerobic conditions, both PC-3 and LNCaP cells exhibited an order of uptake preference as follows: choline>acetate>FDG. In hypoxic cells, the order is reversed, reflecting diverse biochemical responses to hypoxia. These findings may help to explain PET imaging findings of the diverse responses of these tracers in different stages and locations of prostate cancer. Androgen depletion markedly suppressed the uptake of all three tracers in LNCaP cells, which suggests the potential for underestimation of the disease state when PET imaging is performed subsequent to antiandrogen therapy.

Acetates↗
PubMed1986

Mutagenicity of benzylic acetates, sulfates and bromides of polycyclic aromatic hydrocarbons.

Studies were performed to determine the direct mutagenicity of the acetates and some bromides and sulfates of hydroxymethyl polycyclic aromatic hydrocarbons in S. typhimurium strains TA98 and TA100. Benzylic acetates, bromides and sulfates were synthesized and characterized. The compounds tested were benzyl alcohol, 5-hydroxymethylchrysene, 1-hydroxymethylpyrene, 6-hydroxymethylbenzo[a]pyrene, 6-(2-hydroxyethyl)benzo[a]pyrene, 6-hydroxymethylanthanthrene, 9-hydroxymethylanthracene, 9-hydroxymethyl-10-methylanthracene, 7-hydroxymethylbenz[a]anthracene, 7-(2-hydroxyethyl)benz[a]anthracene, 12-hydroxymethylbenz[a]anthracene, 7-hydroxymethyl-12-methylbenz[a]anthracene, 12-hydroxymethyl-7-methylbenz[a]anthracene, 1-hydroxy-3-methylcholanthrene, 2-hydroxy-3-methylcholanthrene, 3-hydroxy-3, 4-dihydrocyclopental[cd]pyrene and 4-hydroxy-3, 4-dihydrocyclopental[cd]pyrene. The benzylic sulfate esters of 6-hydroxymethylbenzo[a]pyrene and 7-hydroxymethylbenz[a]anthracene were the most mutagenic compounds, whereas the aliphatic sulfate ester of 7-hydroxyethylbenz[a]anthracene did not cause an increase in mutations above background. All meso-anthracenic benzylic acetate esters were mutagenic in both strains with various degrees of activity, whereas the corresponding non-benzylic esters were inactive, as expected. Of the non-meso-benzylic acetate esters, only the 3-acetoxy-3, 4-dihydrocyclopenta[cd]pyrene was mutagenic. In the benzylic bromide series, only the eight mesoanthracenic were mutagenic, whereas benzyl bromide and 5-bromomethylchrysene were inactive. The aliphatic bromides, 6-(2-bromoethyl)benzo[a]pyrene and 7-(2-bromoethyl)benz[a]anthracene did not display significant activity. The potencies of the acetate esters more accurately reflect the mutagenicity because the rate of solvolysis did not compete with the reactivity of the esters with bacterial DNA. In the case of benzylic sulfates and bromides, the rate of solvolysis was very rapid and could have diminished the level of mutagenicity, depending on the assay conditions. These results demonstrate that meso-anthracenic benzylic acetates, sulfates and bromides are mutagenic, whereas benzylic acetate esters attached to other carbon atoms are inactive.

Acetates↗
PubMed1999

A randomized comparison of continuous combined transdermal delivery of estradiol-norethindrone acetate and estradiol alone for menopause. CombiPatch Study Group.

OBJECTIVE: To determine whether a continuous estradiol-norethindrone acetate transdermal delivery system reduces incidence of endometrial hyperplasia in postmenopausal women more than transdermal estradiol (E2) alone. METHODS: Six hundred twenty-five postmenopausal women were assigned randomly to one of four treatments, transdermal E2 50 microg/day, or transdermal E2-norethindrone acetate with 50 microg E2 and 140, 250, or 400 microg/day of norethindrone acetate. Follow-up visits to collect information on safety and efficacy were scheduled at 3, 6, 9, and 12 months after initiation of treatment. Endometrial biopsy for histologic evaluation was done at baseline and upon exit from the study (completion or withdrawal). Endometrial histology was evaluated by two independent gynecologic pathologists. In the event of a disparate reading, a third gynecologic pathologist evaluated the tissue using predetermined criteria. RESULTS: Endometrial hyperplasia was found in 37.9% (39 of 103) in the E2 alone group versus 0.8% (one of 123), 1% (one of 98), and 1.1% (one of 89) in the E2-norethindrone acetate 50-140, 50-250, and 50-400 groups, respectively (P < .001). Uterine bleeding was less frequent in the E2-norethindrone acetate 50-140 group than other treatments. The mean number of hot flushes per day decreased to less than one in each treatment group at endpoint. The E2-norethindrone acetate combination patch showed skin tolerance comparable to that of E2 alone. CONCLUSION: Continuous transdermal delivery of E2 combined with norethindrone acetate effectively prevented endometrial hyperplasia in healthy postmenopausal women. Continuous combined transdermal delivery systems provide increased dosing flexibility and might improve convenience and compliance with hormone replacement therapy.

Administration, Cutaneous↗
PubMed1997

Biomonitoring of technical grade 1-alkoxy-2-propanol acetates by analysing urinary 2-alkoxypropionic acids.

Today commercially available 1-alkoxy-2-propanol acetates contain a harmful isomer 2-alkoxy-1-propanol acetates, which makes up less than 20% of the commercial product. This harmful isomer provides a means with which to study the toxicity and exposure to alkoxypropanols. Assessing exposure to technical grade 1-alkoxy-2-propanol acetates through the biological monitoring of urinary 2-alkoxypropionic acids has been found to be the most accurate method. The method developed in this study provides a procedure for the simultaneous urinalysis of methoxyacetic acid (MAA), ethoxyacetic acid (EAA), butoxyacetic acid (BAA), oxalic acid (OA), 2-methoxypropionic acid (2-MPA) and 2-ethoxypropionic acid (2-EPA). This possibility is very valuable in workplaces where workers are exposed simultaneously to different glycol ethers. This study was conducted among 54 silkscreen printers, who gave a urine sample to be analysed using a capillary gas chromatograph for 2-MPA and 2-EPA. The mean urinary concentrations of 2-MPA and 2-EPA were 1.27 (S.D. = 1.60) nmol/mol creatinine (median = 0.53, n = 26) and 1.23 (S.D. = 2.31) mmol/mol creatinine (median = 0.26, n = 39), respectively. The urinary excretion of 2-MPA and 2-EPA immediately after shift was linearly dependent on the preceding technical grade 1-methoxy-2-proponol acetate (7 = 0.16x + 0.26, n = 26 R2 = 0.78) and technical grade 1-ethoxy-2-propanol acetate (y = 2.05x - 0.09, n = 39, R2 = 0.68) respective exposure, as measured in the workers' breathing zone. According to the results of this study it is possible to monitor exposure to the technical grade 1-methoxy-2-propanol acetate and technical grade 1-ethoxy-2-propanol acetate through urinalysis of 2-MPA and 2-EPA.

Acetates↗
PubMed2003

Behavioral effects of intraventricular injections of low doses of ethanol, acetaldehyde, and acetate in rats: studies with low and high rate operant schedules.

Although ethanol is typically classed as a sedative-hypnotic, low doses of ethanol have been shown to stimulate locomotor activity in mice. However, in rats the typical response to peripheral administration of ethanol is a dose-dependent suppression of motor activity and operant responding. The present study was undertaken to determine the effects of intraventricular (ICV) infusions of ethanol, acetaldehyde, and acetate on operant performance in rats. ICV injections of ethanol, acetaldehyde, or acetate were given to rats previously trained on either a differential-reinforcement-of-low-rates-of-responding (DRL) 30-s schedule, which generates low rates of responding, or a fixed ratio 5 (FR5) schedule, which generates relatively high rates. Ethanol, acetaldehyde, and acetate all produced a rate-increasing effect in rats on the DRL 30-s schedule at moderate doses (2.8 and 1.4 micromol, respectively). Acetate also produced a rate-decreasing effect on the DRL 30-s schedule at a larger dose (8.8 micromol). Performance on the FR5 schedule was unaltered by ethanol and acetaldehyde, even at doses as high as 17.6 micromol. However, acetate produced a rate-decreasing effect on the FR5 schedule at doses of 4.4, 5.6, and 8.8 micromol. Central administration of low doses of ethanol and its metabolites can increase operant responding on some schedules in rats. Acetate is the substance that is most potent for producing rate-suppressing effects. These results indicate that the major metabolites of ethanol are pharmacologically active when injected into the brain, and suggest that acetate may mediate some of the rate-suppressing effects of ethanol, such as sedation, ataxia or motor slowing.

Acetaldehyde↗
PubMed2003

Lysine synthesis control in Corynebacterium glutamicum RC 115 in mixed substrate (glucose-acetate) medium.

The effect of acetate as a glucose co-substrate on growth, lysine synthesis and experimental lysine yield from carbon substrates by Corynebacterium glutamicum RC 115 was investigated. It was found that low amounts of acetate, injected with a glucose-acetate pulse into the steady-state continuous culture in bioreactor, caused a slight decrease in the specific rates of glucose uptake and bacterial growth, but a significant increase in the cell specific rate of lysine synthesis and an increase in lysine yield. In contrast, acetate injected in high amounts was followed by a drastic decrease in the values of these parameters. A strong increase in experimental lysine yield under the latter conditions was reached in the response to pyruvate addition. Therefore it was shown that acetate in low concentrations can be used as a glucose co-substrate to increase the cell specific rate of lysine synthesis and lysine yield by C. glutamicum RC 115. Pyruvate supplementation was found as a promising method to enhance lysine synthesis by bacterial cells grown in glucose-acetate media with an increased concentration of acetate.

Acetates↗
PubMed2000

Anaerobic thermophilic fermentation for acetic acid production from milk permeate.

Fermentation of milk permeate to produce acetic acid under anaerobic thermophilic conditions (approximately 60 degrees C) was studied. Although none of the known thermophilic acetogenic bacteria can ferment lactose, it has been found that one strain can use galactose and two strains can use lactate. Moorella thermoautotrophica DSM 7417 and M. thermoacetica DSM 2955 were able to convert lactate to acetate at thermophilic temperatures with a yield of approximately 0.93 g g(-1). Among the strains screened for their abilities to produce acetate and lactate from lactose, Clostridium thermolacticum DSM 2910 was found precisely to produce large amounts of lactate and acetate. However, it also produced significant amounts of ethanol, CO2 and H2. The lactate yield was affected by cell growth. During the exponential phase, acetate, ethanol, CO2 and H2 were the main products of fermentation with an equimolar acetate/ethanol ratio, whereas during the stationary phase, only lactic acid was produced with a yield of 4 mol per mol lactose, thus reaching the maximal theoretical value. When this bacterium was co-cultured with M. thermoautotrophica, lactose was first converted mainly to lactic acid, then to acetic acid, with a zero residual lactic acid concentration and an overall yield of acetate around 80%. Under such conditions, only 13% of the fermented lactose was converted to ethanol by C. thermolacticum.

Acetic Acid↗
PubMed2000

Reliability of digital videometry and acetate tracing in measuring the surface area of cutaneous wounds.

PURPOSE: The purpose of this study was to evaluate the reliability of digital videometry and acetate tracing in the measurement of cutaneous wound area. METHODS: Four clinicians used both digital videometry and acetate tracing to measure five wounds that were artificially created on a cadaver specimen. In addition, the clinicians used an analog centimeter ruler to determine a rough estimate of the area of each wound. The wounds were measured a total of five times with each measurement instrument using a non-sequential repeat measures design. Associations between the three wound measurement techniques were examined with Pearson correlation coefficients. In addition, intraclass correlation coefficients (ICC) were calculated for each pair of the three measurement techniques. RESULTS: Correlation between the measurement systems for all raters combined yielded Pearson r-values of 0.93 for ruler and acetate, 0.95 for ruler and digital and 0.97 for acetate and digital. Furthermore, the average measure ICC between acetate and digital was 0.94, between acetate and ruler was 0.76 and between digital and ruler was 0.57. CONCLUSION: These results suggest that wound area measurements obtained using digital videometry and acetate tracing are very similar and both techniques can be used interchangeably in either clinical or research settings.

Acetates↗
PubMed1997

Acetate and propionate potentiate the antiproliferative effect of butyrate on RBL-2H3 growth.

1. The effect of acetate, propionate, and butyrate separately and combined on RBL-2H3 (a rat basophilic leukemic cell type) proliferation during 24, 48, and 72 hr was examined. Also, the effect of a mixture of the three volatile fatty acids on proliferation of HeLa-155 (a human adenocarcinoma), C57 B1/6J (a mouse melanoma), and MCF-7 (human breast tumor) during 8 days was investigated. 2. Acetate and propionate per se did not present any effect on RBL-2H3 growth during 72 hr, however, when acetate and propionate were added together a significant inhibition of this cell growth was found; 18% for 48 and 37% for 72 hr. The addition of butyrate to the culture medium caused a 75% decrease in the rate of this cell growth either after 48 and 72 hr. This effect of butyrate was pronounced by acetate (86% and 90% for 48 and 72 hr, respectively), propionate (87% for 48 and 93% for 72 hr), and acetate and propionate together (76% for 48 and 92% for 72 hr). 3. Daily addition of a mixture of the short-chain fatty acids (10 mM acetate, 2 mM propionate and 1.5 mM butyrate) markedly decreased the number of cells after 8 days: 58% for RBL-2H3, 42% for HeLa-155, 91% for C57 B1/6J and 55% for MCF-7. 4. These results support the proposition that a fiber-rich diet that leads to great production of butyrate but also of propionate and acetate would be more effective to prevent the occurrence of colorectal cancer than the administration of this short-chain fatty acid given alone.

Acetates↗
PubMed1997

Effects of carbonylcyanide-m-chlorophenylhydrazone (CCCP) and acetate on Escherichia coli O157:H7 and K-12: uncoupling versus anion accumulation.

Non-growing cells of Escherichia coli O157:H7 and K-12 that were incubated anaerobically in sodium phosphate buffer at pH 6.5 consumed glucose at a rate of approximately 8 mumol.(mg protein)-1.h-1 and had intracellular pH values of 7.3 and 7.5, respectively. The uncoupler, carbonylcyanide-m-chlorophenylhydrazone (CCCP), caused a marked decrease in intracellular pH, ATP and potassium of both strains. Low concentrations of CCCP stimulated glucose consumption rate, but higher concentrations were inhibitory. Acetate also caused a decrease in intracellular pH, but it never caused a large decrease in glucose consumption rate. Acetate decreased the intracellular ATP of E. coli K-12, but it had no effect on the ATP of O157:H7. Acetate had no effect on the intracellular potassium of E. coli O157:H7, and acetate-treated K-12 cells had even more potassium than untreated controls. Based on these results, acetate and CCCP appear to have different effects on E. coli. The comparison of E. coli O157:H7 and K-12 indicated that intracellular pH, acetate accumulation and intracellular potassium were related. E. coli K-12 maintained a higher intracellular pH than O157:H7, accumulated more acetate and had a greater intracellular potassium.

Acetates↗
PubMedDate not supplied

Feasibility of planar myocardial carbon 11-acetate imaging.

BACKGROUND: Myocardial oxygen consumption can be determined by using carbon 11-acetate (11C-acetate) and positron emission tomography (PET). The aim of this study was to validate planar 11C-acetate scintigraphy in healthy individuals by relating the myocardial clearance rate of dynamic 11C-acetate scintigraphy with the rate-pressure product, which is used as a measure of cardiac work. Also, the optimal curve-fitting procedure of the time-activity curve and the intraobserver and interobserver variation of determining the clearance rates were assessed. METHODS AND RESULTS: Six subjects were studied at rest, and seven subjects were studied during dobutamine stimulation. Imaging was performed with a planar camera equipped with high-energy collimators for 45 minutes after the injection of 185 MBq of 11C-acetate. Myocardial time-activity curves were corrected for decay. During the study, heart rates and blood pressures were measured to calculate the rate-pressure product. Myocardial time-activity curves showed a clear biphasic pattern. Clearance rates were expressed in k values. The best fitting procedure, as assessed by means of the lowest error of k and the best correlation with the rate-pressure product, proved to be a monoexponential fit on the first part of the time-activity curve (kmono). Subjects studied during dobutamine infusion had significantly higher rate-pressure product (15.0 +/- 2.1*10(3) vs 8.6 +/- 1.2*10(3), P < .001) and 11C-acetate clearance rates (kmono = 0.0657 +/- 0.0110 vs 0.0313 +/- 0.0056, P < .0001) than subjects studied at rest. There was low intraobserver and interobserver variation in determining kmono values. A significant correlation between the rate-pressure product and the monoexponential clearance rate was found (kmono = 5.11*10(-6)*RPP-0.012; r = 0.94, P < .001). CONCLUSIONS: The estimation of myocardial oxygen consumption is feasible with planar 11C-acetate scintigraphy. Clearance rates and the relation with the rate-pressure product are similar to those reported in PET studies. This technique may be used for the assessment and follow-up of global myocardial metabolic abnormalities, eg, in patients with hypertensive heart disease, cardiomyopathy, myocarditis, and valvular disease.

Acetates↗
PubMed2003

Effect of acetic acid added to cooking water on the dissolution of proteins and activation of protease in rice.

The effect of acetic acid on the dissolution of proteins in rice was studied to elucidate the mechanism for the textural change induced by the acid by chemical and SDS-PAGE analyses of the rice proteins in the soaking solution. More proteins were extracted with 0.2 M acetic acid (pH 2.7) than with water (pH 6.8). The effect of acetic acid on the protein dissolution increased with increasing temperature. Immunoblotting confirmed that, when rice was soaked in acetic acid, glutelin was dissolved into the soaking solution and degraded by aspartic proteinase. Aspartic proteinase degraded glutelin much more than it did albumin and globulin. It was found that the combined amount of albumin and globulin dissolved into the acetic acid solution was much larger than that of glutelin, despite the smaller amounts present of albumin and globulin than of glutelin. Metal ions were extracted more with acetic acid than with water. In addition, carboxypeptidase was activated under the acidic condition and resulted in an increase in the amount of free amino acids. The main effect of acetic acid on the dissolution of rice proteins was enhancement of the solubility of albumin, globulin, and glutelin, the effect of proteases being minor.

Acetic Acid↗
PubMedDate not supplied

Proteome of Methanosarcina acetivorans Part II: comparison of protein levels in acetate- and methanol-grown cells.

Methanosarcina acetivorans is an archaeon isolated from marine sediments which utilizes a diversity of substrates for growth and methanogenesis. Part I of a two-part investigation has profiled proteins of this microorganism cultured with both methanol and acetate as growth substrates, utilizing two-dimensional gel electrophoresis and MALDI-TOF-TOF mass spectrometry. In this report, Part II, the analyses were extended to identify 34 proteins found to be present in different amounts between methanol- and acetate-grown M. acetivorans. Among these proteins are enzymes which function in pathways for methanogenesis from either acetate or methanol. Several of the 34 proteins were determined to have redundant functions based on annotations of the genomic sequence. Enzymes which function in ATP synthesis and steps common to both methanogenic pathways were elevated in acetate- versus methanol-grown cells, whereas enzymes that have a more general function in protein synthesis were in greater amounts in methanol- compared to acetate-grown cells. Several group I chaperonins were present in greater amounts in methanol- versus acetate-grown cells, whereas lower amounts of several stress related proteins were found in methanol- versus acetate-grown cells. The potential physiological basis for these novel patterns of protein synthesis are discussed.

Acetates↗
PubMed2000

Corticosteroid pretreatment prevents small intestinal mucosal lesion induced by acetic acid-perfusion model in rats.

One of the important problems in experimentally induced small intestinal lesions is that there is no reproducible model of diffuse and stable mucosal lesion. In this paper, we studied in detail the effects of continuous perfusion of various concentrations of acetic acid on the rat small intestinal mucosa. In order to evaluate its applicability for screening of the preventive effect of drugs on gut damage, we also evaluated the efficacy of corticosteroid pretreatment in preventing acetic acid-induced mucosal lesion. Male Sprague-Dawley rats were fasted for 12 hr, and the small intestinal lumen was perfused with 1%, 1.5%, 2.5%, 3%, 3.75% (pH 2.4-2.6) acetic acid or saline (control) at 1 ml/min for 15 min. In separate experiments, the effect of preadministration of budesonide (0.5 or 0.75 mg/kg/day) and prednisone (0.75 mg/kg/day) on 1.5% acetic acid-induced mucosal damage was investigated. Macroscopic and microscopic lesions occurred diffusely in a concentration-dependent fashion. Histological findings revealed signs of transmural inflammation characterized by mucosal-submucosal edema, ulceration, and neutrophil infiltration. Mucosal-submucosal height had an inverse relation with the acetic acid concentrations perfused. Myeloperoxidase activity levels increased several-fold in the acetic acid-perfused groups. Corticosteroid pretreatment prevented microscopic damage and was associated with reduction of MPO activity levels in 1.5% acetic acid-perfused rats. We conclude that this simple and reproducible model could be applied for the screening of new drugs in the gastrointestinal tract in which large numbers of animals are taken into account.

Acetic Acid↗
PubMed2006

A combined stopped-flow, electrospray ionization mass spectrometry and (31)P NMR study on the acetic acid-mediated fragmentation of the hydroxo-chalcogenide cluster [W(3)Se(4)(OH)(3)(dmpe)(3)](+) (dmpe = 1,2-bis(dimethylphosphanyl)ethane) to yield the dinuclear [W(2)Se(2)(mu-Se)(2)(mu-CH(3)CO(2))(dmpe)(2)](+) complex.

The reaction of the incomplete-cuboidal [W(3)Se(4)(OH)(3)(dmpe)(3)](+) ([1](+)) cluster with acetic acid in acetonitrile solution leads to cluster fragmentation with formation of the dinuclear [W(2)Se(2)(mu-Se)(2)(mu-CH(3)CO(2))(dmpe)(2)](+) ([2](+)) complex. The X-ray structure of [2]PF(6) presents two equivalent metal centres bridged by one acetate ligand. Each W atom is additionally coordinated by one terminal selenium atom, two bridging selenido and two diphosphane phosphorus atoms in an essentially octahedral environment. Stopped-flow and conventional UV-vis studies indicate that fragmentation of [1](+) into [2](+) occurs through a complex mechanism. Three steps can be distinguished in the stopped-flow time scale, all of them showing a first order dependence with respect to the acetic acid concentration, followed by very slow spectral changes that lead to the formation of [2](+). Phosphorus NMR, electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MS/MS) have been used to identify the nature of the reaction intermediates formed in the different steps. These studies indicate that the first two steps correspond to the formal substitutions of the hydroxo ligands at two metal centres by terminal acetate ligands. The third step involves bridging of one of the terminal acetate ligands, which actually prepares the trinuclear cluster to afford the acetate-bridged [W(2)Se(2)(mu-Se)(2)(mu-CH(3)CO(2))(dmpe)(2)](+) ([2](+)) complex. Although the precise details of the final conversion to [2](+) have not been established, the results obtained by combination of the different experimental techniques provide a complete picture of the speciation of the cluster [1](+) in acetonitrile solutions containing acetic acid.

Acetic Acid↗
PubMed1978

Control of isocitrate lyase synthesis in Chlorella fusca var. vacuolata. Rate of enzyme synthesis in the presence and absence of acetate measured by [35S]methionine labelling and immunoprecipitation.

The rate of increase of isocitrate lyase activity was measured in darkened Chlorella fusca var. vaculoata cultures in the presence and absence of acetate and compared with the rate of incorporation of [35S]methionine into isocitrate lyase enzyme protein under the same conditions. Isocitrate lyase enzyme protein was isolated for this purpose by specific immunoprecipitation and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. After 4h in the dark, in the presence of acetate the rate of increase of isocitrate lyase activity was 75 times that in the absence of acetate. Incorporation of [35S]methionine into isocitrate lyase was 140 times greater in the presence of acetate. Incorporation of [35S]methionine into the trichloroacetic acid-insoluble fraction overall was about five times as fast in the presence of acetate. These data are not consistent with an increased turnover of isocitrate lyase enzyme molecules, sufficient to account for the low rate of increase of isocitrate lyase activity in the absence of acetate. The greater rate of enzyme synthesis in the presence of acetate must therefore be due to some effect of this metabolite on the processing or translation of isocitrate lyase mRNA.

Acetates↗