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At least 127 records · Page 7Linked to original sources
PubMed2003

[Study on recovery of ethyl acetate after extracting tripterygium wifordii extractum with ethyl acetate].

OBJECTIVE: To increase the recovery rate of ethyl acetate after extracting tripterygium wifordii extractum and to decrease product cost. METHOD: After extracting tripterygium wifordii extractum with ethyl acetate, 3 times saturated salt water was added in it so as to recovery ethyl acetate distilled under normal atmospheric pressure. Ethyl acetate containing salt water was purified through Na2SO4 column. RESULT: Ethyl acetate purified could be used repeatedly and the recovery rate was up to 85%. CONCLUSION: This method is completely adapted for mass production.

Acetates↗
PubMed2004

The analysis of the zero-order and the second derivative spectra of retinol acetate, tocopherol acetate and coenzyme Q10 and estimation of their analytical usefulness for their simultaneous determination in synthetic mixtures and pharmaceuticals.

The aim of the present work was to develop a simple and rapid method of retinol acetate, tocopherol acetate and coenzyme Q(10) determination in pharmaceuticals without involving any preparation operations like separation or masking. The values of second derivative amplitude at 212 nm for tocopherol, 351 nm for retinol and 222 nm for coenzyme were used for construction of calibration graphs. Beer's law is obeyed in the concentration range 0.5-20, 0.5-7.5 and 0.5-30 microg ml(-1) for retinol acetate, tocopherol acetate and coenzyme, respectively. The elaborated procedures were successfully applied to the simultaneous determination of studied compounds in their binary synthetic mixtures and in commercial preparations with high reliability and repeatability. Spectral properties of retinol acetate allows to determine its contents in ternary mixture which includes Vitamin E and coenzyme Q(10).

Chemistry Techniques, Analytical↗
PubMed2003

Synthesis, characterization, and use of 2-[(2H(9))butoxy]acetic acid and 2-(3-methylbutoxy)acetic acid as an internal standard and an instrument performance surrogate, respectively, for the gas chromatographic-mass spectrometric determination of 2-butoxyacetic acid, a human metabolite of 2-butoxyethanol.

2-[(2H(9))Butoxy]acetic acid and 2-(3-methylbutoxy)acetic acid were synthesized, mixed with 2-butoxyacetic acid, and separated by capillary gas chromatography on a fused-silica column with a length of 50 m, inside diameter of 0.200 mm, and a "free fatty acid phase" wall coating of 0.3 microm film. 2-[(2H(9))Butoxy]acetic acid, 2-butoxyacetic acid, and 2-(3-methylbutoxy)acetic acid were baseline resolved at retention times of 13.55, 13.78, and 15.20 min; 2-(3-methylbutoxy)acetic acid having a peak efficiency of 360,000. Mass spectrometric detection using selected ion monitoring at m/z 66, 57, and 71 showed linear analytical responses from 0.04 ng to at least 200 ng with a limit of detection of 0.04 ng for 2-butoxyacetic acid.

Calibration↗
PubMed1996

On-Line Monitoring of the Photolysis of Benzyl Acetate and 3,5-Dimethoxybenzyl Acetate by Membrane Introduction Mass Spectrometry.

Membrane introduction mass spectrometry (MIMS) allows on-line monitoring of the products of photolysis (254 nm) of benzyl acetate in aqueous methanol and 3,5-dimethoxybenzyl acetate in water. The reaction mixture is continuously exposed to a silicone membrane through which analyte molecules permeate into a triple quadrupole mass spectrometer for qualitative and quantitative analysis. Ionization is achieved by either isobutane or ammonia chemical ionization, and ions characteristic of the reactant ester and its products are monitored simultaneously and continuously. Three products, benzyl methyl ether, ethylbenzene, and bibenzyl are observed in the benzyl acetate photolysis. Two products, 3,5-dimethoxybenzyl alcohol and 3,5-dimethoxyethylbenzene, are formed in the photolysis of 3,5-dimethoxybenzyl acetate. Quantitation is achieved through calibration using external standard solutions and, in the case of benzyl methyl ether, tandem mass spectrometry is used to verify product identification. During the photolysis of benzyl acetate, benzyl methyl ether and ethylbenzene are produced at onset with similar efficiencies. For the 3,5-dimethoxy ester photolysis, performed in aqueous solution, the efficiency of formation of the polar product 3,5-dimethoxybenzyl alcohol is about 300 times greater than that of the nonpolar product 3,5-dimethoxyethylbenzene. The results show that the relative reaction rates are dependent on the solvent and on the photon intensity and are consistent with earlier off-line experiments by Pincock et al. which showed that the photolysis proceeds through both ion and radical pair intermediates. To the best of our knowledge, the work reported here describes the first analysis of the photochemistry of an aralkyl ester in water and the first use of on-line mass spectrometry in a mechanistic study.

Journal Article↗
PubMed1986

Comparison of plasma alpha and gamma tocopherol levels following chronic oral administration of either all-rac-alpha-tocopheryl acetate or RRR-alpha-tocopheryl acetate in normal adult male subjects.

Vitamin E was administered orally (400 IU twice a day) to adult male humans for 28 days as either dl-alpha-tocopheryl acetate (all-rac-alpha-tocopheryl acetate) or d-alpha-tocopheryl acetate (RRR-alpha-tocopheryl acetate). Plasma alpha-tocopherol rose rapidly and fell at the same rate following cessation of supplementation with both forms of vitamin E. No significant differences in plasma alpha- or gamma-tocopherol levels were found between the two forms of vitamin E following their administration. The results confirm the currently accepted biopotencies of 1.0 IU/mg and 1.36 IU/mg, respectively for the two forms of vitamin E. Supplementation with either form of alpha-tocopheryl acetate resulted in depressing plasma gamma-tocopherol to less than 1/3 of initial levels; also the gamma/alpha ratio was depressed to less than 1/7 of the initial value. The study suggests that the gamma/alpha vitamin E ratio might also serve as a sensitive index of alpha-tocopherol ingestion.

Administration, Oral↗
PubMed1992

A new automated method for phenotyping arylesterase (EC 3.1.1.2) based upon inhibition of enzymatic hydrolysis of 4-nitrophenyl acetate by phenyl acetate.

A new method for phenotyping human serum arylesterase (EC 3.1.1.2) is described and evaluated. The aromatic esters, phenyl acetate and 4-nitrophenyl acetate, were compared as substrates for spectrophotometric measurement of arylesterase activity. A method for arylesterase phenotyping, based upon inhibition of the enzymatic hydrolysis of 4-nitrophenyl acetate by phenyl acetate, was developed. The method was applied to serum samples from 158 blood donors and showed a distinct separation of the three phenotypes defined by a reference method based on the ratio of paraoxonase activity to arylesterase activity using paraoxon and phenyl acetate as substrates. The method was adapted to a Cobas-Fara centrifugal analyser.

Alleles↗
PubMed1992

Granulocyte elastase, beta-thromboglobulin, and C3d during acetate or bicarbonate hemodialysis with Hemophan compared to a cellulose acetate membrane.

Twenty-two patients were dialysed in a cross-over design using Hemophan or cellulose acetate membranes. The dialysate buffer was acetate (n = 12) or bicarbonate (n = 10). Blood was sampled at 0, 15, 60 and 180 min and mean values were adjusted for changes in total protein in each sample. At 15 min during dialysis a decrease in leukocytes and platelets occurred with both membranes, irrespective of the buffer (Wilcoxon, p less than 0.006). During dialysis, increases were found in granulocyte elastase inhibitor complex (E- alpha 1-PI), beta-thromboglobulin and C3d. beta 2-microglobulin was not significantly changed in blood after dialysis with Hemophan or cellulose acetate membranes with bicarbonate buffer. Side effects were more pronounced at 180 min during dialysis with bicarbonate in patients using cellulose acetate than with Hemophan (p = 0.021, n = 8). Hemophan seemed to be more favourable than cellulose acetate membranes in regard to leukopenia and E- alpha 1-PI. The dialysate buffer may also alter membrane biocompatibility.

Biocompatible Materials↗
PubMedDate not supplied

Reverse phase liquid chromatographic determination of dexamethasone acetate and cortisone acetate in bulk drug substances and dosage forms: method development.

The determination of the steroid acetates was evaluated for ruggedness of the method by using an octyldecylsilane column, 254 nm detection, and acetonitrile-water as mobile phase. Mobile phase pH, oven temperature, and columns from various manufacturers had no dramatic effect on the chromatography. The method was then optimized for dexamethasone acetate and cortisone acetate bulk drug and dosage forms. For dexamethasone acetate, the bulk drug substance should be dried at 105 degrees C before use, and the sample should be dissolved in 50% acetonitrile-buffer pH 6 for stability. Cortisone acetate, on the other hand, was found to be nonhygroscopic and hence could be used as received. For stability, the sample should be stored in 50% acetonitrile-buffer pH 4.

Chromatography, Liquid↗
PubMed1986

Cardiovascular side effects of diethylstilbestrol, cyproterone acetate, medroxyprogesterone acetate and estramustine phosphate used for the treatment of advanced prostatic cancer: results from European Organization for Research on Treatment of Cancer trials 30761 and 30762.

Two randomized trials were started in 1976 by the European Organization for Research on Treatment of Cancer urological group. Trial 30761 compared 1 mg. diethylstilbestrol orally 3 times daily to 250 mg. oral cyproterone acetate daily and to 500 mg. medroxyprogesterone acetate intramuscularly 3 times weekly for 8 weeks, then 200 mg. orally daily. Trial 30762 compared 3 mg. diethylstilbestrol to 560 mg. estramustine phosphate orally for 8 weeks and then 280 mg. daily. The 239 patients in study 30761 and 226 in study 30762 were evaluated for cardiovascular toxicity during treatment. Various types of side effects (fluid retention, hypertension, electrocardiographic changes, myocardial infarction and thromboembolic disease) and their degrees of severity were analyzed. In both studies the most frequent type of cardiovascular toxicity was represented by fluid retention. Cardiovascular toxicity as a whole was higher with diethylstilbestrol than with estramustine phosphate or medroxyprogesterone acetate therapy, and was the lowest with cyproterone acetate therapy. The risk of severe cardiovascular complications developing was the highest during the first 6 months of treatment. Increasing age, body weight greater than 75 kg. and, especially, the presence of previous cardiovascular disease represented adverse factors in the development of cardiovascular toxicity.

Aged↗
PubMed1990

Determination of megestrol acetate and cyproterone acetate in serum of patients with advanced breast cancer by high-performance liquid chromatography.

A reversed-phase high-performance liquid chromatographic method with ultraviolet detection of megestrol acetate and cyproterone acetate in human sera is described. The proposed assay is linear up to 1400 ng/ml (r = 0.999) and has a detection limit of 5 ng/ml. Recoveries of both compounds in spiked sera were ca. 95%; inter-assay coefficients of variation were 4.0 and 3.1% and intra-assay values were 1.3 and 1.4%, respectively. For validation of the method we also developed a gas chromatographic-mass spectrometric method for both steroids. The results obtained by the two methods showed good correlation: for megestrol acetate r = 0.98, n = 31, p less than 0.0001, and for cyproterone acetate r = 0.94, n = 0, p less than 0.0001. Large inter-individual differences in the serum concentrations of both substances were found in groups of patients with metastatic breast cancer receiving the same oral load of either steroid.

Antineoplastic Agents↗
PubMed1996

Modified technique to recover microsporidian spores in sodium acetate-acetic acid-formalin-fixed fecal samples by light microscopy and correlation with transmission electron microscopy.

Microsporidia are an emerging cause of significant disease, particularly in the immunocompromised host. Until recently, the diagnosis of enteric infections has required invasive sampling, the use of expensive technology, and considerable technological expertise. The purpose of the present study was to examine three modifications to the processing of fecal specimens for light microscopy (LM) examination for microsporidian spores: the use of pretreatment with potassium hydroxide, modified centrifugation conditions, and a modified staining technique. A sodium acetate-acetic acid-formalin-fixed fecal sample containing numerous microsporidian spores confirmed to be positive by transmission electron microscopy (TEM) was used in all studies performed. A simulation of a heavy to lightly infected individual was used. The results of LM were correlated with those of TEM. Duplicate smears were stained with Weber's modified trichrome and Giemsa (GS) stains. The stained slides were randomized and examined blindly by LM at x 625 and x 1,250 magnifications. A portion of the dilutions after centrifugation were fixed for TEM. The Weber modified trichrome stain performance rating was higher than the Giemsa stain rating because of ease of interpretation, and material stained with Weber modified trichrome stain required less examination time at a lower magnification. The number of positive smears and the quantity of spores detected were significantly higher following pretreatment of the sample with KOH. TEM was positive only when numerous spores were present, but the quality of the photomicrographs was superior after pretreatment with KOH. Pretreatment of sodium acetate-acetic acid-formalin-fixed fecal samples with 10% KOH and then a 5-min centrifugation time and staining with Weber modified trichrome stain provide for the excellent recovery of microsporidia in the routine diagnostic parasitology laboratory.

AIDS-Related Opportunistic Infections↗
PubMed1990

Inorganic elements in the tooth and bone tissues of rats bearing nickel acetate- and lead acetate-induced tumors.

Biological effects of such metals as nickel and chromium alloys used as dental materials, particularly their metabolism and potential toxicity have not been well elucidated. Certain metallic materials are known to be toxic and arsenic, nickel, chromium and lead have been shown to have carcinogenic potential in laboratory animals. This study was performed to assess carcinogenicity and accumulation in tissues of metals in rats. Three-week old male F344/NSle rats were injected s. c. with 30 mg/kg of nickel acetate or 60 mg/kg of lead acetate weekly for 5 weeks after 2 weeks of acclimatization, and were followed by observation for 80 weeks. The group treated with lead acetate showed a greater incidence of tumor, compared with the nickel acetate-treated group. Teeth, femora, other bones and neoplastic tissue from tumor-bearing animals were subjected to elemental analysis by spectrophotometry and ICP. High concentrations of Pb were detected in the mandibula, femur and tumor tissue of rats with Pb-induced tumor. In rats with Ni-induced tumor, Ni was not demonstrable in the mandibula, maxilla or tumor tissue and detected in small quantities in the nasal bone and femur. Thus, Pb proved to be retained in tissue at the site of injection and also markedly accumulated in the tooth and femur as assessed 46 weeks after injections; whereas Ni was no longer detectable in tissue at the injection site, nor in tumor tissue but only small quantities in the said bones.

Acetates↗
PubMed1994

X-ray studies on crystalline complexes involving amino acids and peptides. XXVI. Crystal structures of two forms of L-histidine acetate and a comparative study of the amino acid complexes of acetic acid.

L-Histidine acetate crystallizes in two forms: (I) orthorhombic; P2(1)2(1)2(1); a = 5.027, b = 11.126, c = 17.473 A; Z = 4; (II) monoclinic; C2; a = 15.649, b = 9.276, c = 8.566 A; beta = 94.65 degrees; Z = 4. The structures were solved by direct methods and refined to R-values of 0.056 and 0.089 for 1131 and 1330 observed reflections, respectively. The conformations of the histidine molecule in the two forms are different. However, both are such that they facilitate the occurrence of a specific interaction of the histidine molecule with a carboxylate group. The basic elements of aggregation are hydrogen-bonded histidine ribbons, but they are of different types in the two structures. The ribbons are interconnected by acetate ions to form the crystals. The structures contain two characteristic interaction patterns involving amino and carboxylate groups, one of which is observed for the first time. The two water molecules in form II and their symmetry equivalents form an uninterrupted hydrogen-bonded chain running through the crystal. They also present an interesting case of disorder in hydrogen bonds. A comparative study involving amino acid complexes of acetic acid shows that the presence of acetate ion could lead to new aggregation patterns, specific interactions and characteristic interaction patterns with varying degrees of similarity with those observed in other structures containing amino acids.

Acetates↗
PubMed1998

Estradiol inhibits LDL oxidation: do the progestins medroxyprogesterone acetate and norethisterone acetate influence this effect?

Estrogen replacement therapy in postmenopausal women must be combined with progestin to avoid endometrial cancer. However, progestin addition could antagonize cardioprotective effects of estradiol. Therefore we investigated the effect of the two most commonly used progestins--medroxyprogesterone acetate (progesterone-derivative) and norethisterone acetate (nortestosterone-derivate)--alone and in combination with 17 beta-estradiol on copper-mediated oxidation of low density lipoprotein (LDL). Whereas 17 beta-estradiol alone inhibited the onset of LDL oxidation at the concentrations 0.5, 1.0, 5 and 10 microM, the progestins alone did not demonstrate any significant effect. In the estrogen-progestin combinations of 0.5 microM 17 beta-estradiol with 0.5, 1.0, 5 and 10 microM progestin, respectively, the estradiol effect was not changed. These results suggest that medroxyprogesterone acetate as well as norethisterone acetate do not counteract the beneficial effect of 17 beta-estradiol on LDL oxidation when used in hormone replacement therapy.

Drug Interactions↗
PubMed2006

Subcutaneous injection of depot medroxyprogesterone acetate compared with leuprolide acetate in the treatment of endometriosis-associated pain.

OBJECTIVE: To compare the efficacy and safety of SC depot medroxyprogesterone acetate (DMPA-SC 104) with that of leuprolide acetate in treatment of endometriosis. DESIGN: Phase 3, multicenter, randomized, evaluator-blinded, comparator-controlled trial. SETTING: Clinical trial sites in Canada and United States. PATIENT(S): Two hundred seventy-four women with surgically diagnosed endometriosis. INTERVENTION(S): Intramuscular injections of DMPA-SC (104 mg) or leuprolide acetate (11.25 mg), given every 3 months for 6 months, with 12 months of posttreatment follow-up. MAIN OUTCOME MEASURE(S): Reduction in five endometriosis symptoms or signs (dysmenorrhea, dyspareunia, pelvic pain, pelvic tenderness, pelvic induration); change in bone mineral density (BMD), hypoestrogenic symptoms, bleeding, and weight. RESULT(S): The depot medroxyprogesterone acetate given SC was statistically equivalent to leuprolide in reducing four of five endometriosis symptoms or signs at the end of treatment (month 6) and in reducing all five symptoms after 12 months' follow-up (month 18). Patients in the DMPA-SC 104 group showed significantly less BMD loss than did leuprolide patients at month 6, with scores returning to baseline at 12 months' follow-up. No statistically significant differences in median weight changes were observed between groups. Compared with leuprolide, DMPA-SC 104 was associated with fewer hypoestrogenic symptoms but more irregular bleeding. CONCLUSION(S): Efficacy of DMPA-SC 104 was equivalent to that of leuprolide for reducing endometriosis-associated pain, with less impact on BMD and fewer hypoestrogenic side effects but more bleeding.

Adult↗
PubMed1987

In vitro methane and methyl coenzyme M formation from acetate: evidence that acetyl-CoA is the required intermediate activated form of acetate.

Buffer-soluble extracts of acetate-grown Methanosarcina barkeri catalyzed methanogenesis from acetate in the presence of hydrogen and ATP. The rates of methane formation from either acetate plus ATP, or acetylphosphate without ATP added, were approximately doubled by the addition of coenzyme A (CoA). In vitro methyl group transfer from [2-14C]acetate to form [14CH3]methyl coenzyme M (14CH3S-CoM) was monitored by causing the accumulation of 14CH3S-CoM (14CH3-SCH2CH2SO3-) in the presence of 2-bromoethanesulfonate. The rate of 14CH3S-CoM formation was increased 2.5-fold by 0.2 mM CoA.

Acetates↗
PubMed1997

Proximity of acetate, manganese, and exchangeable deuterons to tyrosine YZ. in acetate-inhibited photosystem II membranes: implications for the direct involvement of YZ. in water-splitting.

The environment of the photosystem II YZ. radical, trapped in the "split-signal" form, is examined in acetate-treated PSII membranes using pulsed EPR methods. The split-signal line shape is simulated with dipolar and exchange couplings to the Mn cluster of 1260 and -28 MHz, respectively. The 1260-MHz dipolar coupling corresponds to a Mn-YZ. distance of 3.5 A in the point dipole limit. A 0.117-MHz dipolar coupling is observed between nonexchangeable deuterons of methyl-deuterated acetate and YZ.. This interaction is modeled with a 3.1-A distance between an acetate methyl group deuteron and the phenoxy oxygen of YZ*. Since acetate inhibition is competitive with Cl-, this result strongly suggests a close proximity between YZ. and the Cl- cofactor binding site. Analysis of pulsed ENDOR and ESEEM experiments investigating the proximity of deuterons exchanged into the vicinity of YZ. after incubation in 2H2O-enriched buffer demonstrates that YZ. trapped in the split-signal form participates in two hydrogen-bonding interactions, in contrast to YD*, which forms a single hydrogen bond. This result is inconsistent with a simple electron transfer role for YZ* and provides direct experimental evidence for a role for YZ* in proton or hydrogen atom transfer.

Acetates↗