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Results for “PERCHLORIC ACID”

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PubMed1990

A modified HPLC technique for simultaneous measurement of 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in cerebrospinal fluid, platelet and plasma.

A sensitive, reliable and simplified HPLC assay for simultaneous measurement of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in human cerebrospinal fluid (CSF), platelets and plasma is described. Perchloric acid is used for one step precipitation of proteins and extraction of 5-HT and 5-HIAA. Precision of the assay has been increased by calibration of the instrument using serotonin-free plasma spiked with known amount of standards and N-w-methyl-5-hydroxytryptamine as internal standard. Integration of the peaks and calculations are achieved by a preprogrammed data module using ratio method. As little as 20 pg/ml of serotonin in the deproteinated sample can be detected using this procedure. In a group of surgical patients, plasma 5-HT concentration is (Mean +/- S D) 3.4 +/- 2.7 ng/ml and that of platelet 748.3 +/- 448.3 ng/10(9) platelets. In CSF, 5-HT is found to be 3.3 +/- 3.4 ng/ml and 5-HIAA is 15.1 +/- 7.3 ng/ml. A good correlation (r = 0.648, p less than .0001) is observed between 5-HT and 5-HIAA in CSF.

Adult↗

PubMed1992

High-performance liquid chromatographic assay for 1-aminocyclopropanecarboxylic acid from plasma and brain.

A reversed-phase high-performance liquid chromatographic method for the analysis of 1-aminocyclopropanecarboxylic acid (ACPC) from plasma or brain tissue is described. Samples were deproteinized with perchloric acid, centrifuged, alkalinized with potassium hydroxide and recentrifuged. The supernatants were derivatized with o-phthaldialdehyde and injected onto a C18 3-microns column (100 mm x 4 mm I.D.) pumped with 1 ml/min methanol-acetonitrile-0.1 M sodium phosphate buffer pH 6.0 (28:5:67, v/v). The retention times for ACPC and the internal standard were 15 and 31 min, respectively. The minimum detectable amount of ACPC was 0.08 nmol. The extraction recovery of ACPC (2.7-270 nmol) from spiked plasma or brain tissue ranged from 88 to 109%. The intra- and inter-day coefficients of variation for 27 nmol ACPC were 3.9 and 4.9%, respectively. This method was utilized to obtain preliminary pharmacokinetic parameters following ACPC administration to mice.

Amino Acids↗

PubMed2004

Energetic salts from N-aminoazoles.

New energetic salts (2, 3, 5, 6, 13, 14, 21, 22) were synthesized via the quaternization of derivatives of N-aminoazoles with nitric or perchloric acid or with iodomethane followed by metathesis reaction with silver nitrate or silver perchlorate. The structure of 2-amino-4,5-dimethyltetrazolium nitrate (21) was confirmed by single-crystal X-ray analysis. Most of the salts exhibit good thermal stabilities and low melting points. By using experimentally determined constant volume combustion energies, the standard molar enthalpies of formation were derived on the basis of designed Hess thermochemical cycles.

Journal Article↗

PubMed2001

Hydroxamic acids as weak base indicators: protonation in strong acid media.

The protonation equilibria of N-phenylbenzohydroxamic, benzohydroxamic, salicylhydroxamic, and N-p-tolylcinnamohydroxamic acids have been studied at 25 degrees C in concentrated sulfuric, hydrochloric, and perchloric acid media; the UV-vis spectral measurements were analyzed using the Hammett equation and the Bunnett-Olsen and excess acidity methods. The medium effects observed in the UV spectral curves were corrected with the Cox-Yates and vector analysis methods. The H(A) acidity function based on benzamides provided the best results. The range of variation of the solvation coefficient m is similar to that of amides, this indicating similar solvation requirements for amides and hydroxamic acids. For the same substrate, the observed variations of pK(BH)(+) with the mineral acid used was justified by formation of solvent-separated ion pairs; for the same mineral acid, the observed changes in pK(BH)(+) can be explained by the solvation of BH(+). The change of the pK(BH)(+) values was in reasonably good agreement with the sequence of the catalytic efficiency of the mineral acids used, HCl > H(2)SO(4) > HClO(4).

Acid-Base Equilibrium↗

PubMed2006

An experimental and theoretical study of interactions between unlike surface anions and increases in the rate of electrochemical reactions.

Experimental and theoretical results are presented on increases in the rate of electrochemical reactions, which are achieved by replacing a small fraction of the original anions in solution with more inhibiting ones. The rate of the electrochemical oxidation of formic acid was substantially increased by replacing a small amount of the supporting electrolyte, perchloric acid, with either sulfuric acid or tetrafluoroboric acid. The largest increases were achieved by substituting mixtures of the last two acids. A theoretical analysis of an electrochemical reaction coupled to anion adsorption is presented. The analysis reveals that, if repulsive forces of appropriate strength form between unlike surface anions, replacing a fraction of the original anions in solution with one or two kinds of more inhibiting anions can increase the rate of reaction.

Journal Article↗

PubMed1983

A simple spectrophotometric method for the direct determination of uric acid in avian excreta.

A procedure was developed for the direct quantitation of uric acid in poultry excreta. It involved the determination of the absorbance of a perchloric acid extract of excreta at 285 nm. Interference from other ultraviolet absorbing material was shown to be negligible. The correlation (r) between this procedure and a recently developed high-performance liquid chromatographic procedure for uric acid content of excreta from birds fed different diets was .993 (P less than .01). It was concluded that this procedure provides a simple and reliable method for the quantitation of uric acid in avian excreta.

Animals↗

PubMed1993

Metabolic flux determination in C6 glioma cells using carbon-13 distribution upon [1-13C]glucose incubation.

A mathematical model of mammalian cell intermediary metabolism is presented. It describes the distribution of the carbon-13 isotope (13C) at the different carbon positions of metabolites in cells fed with 13C-enriched substrates. The model allows the determination of fluxes through different metabolic pathways from 13C- and 1H-NMR spectroscopy and mass spectrometry data. The considered metabolic network includes glycolysis, gluconeogenesis, the citric acid cycle and a number of reactions corresponding to protein or fatty acid metabolism. The model was used for calculating metabolic fluxes in a rat tumor cell line, the C6 glioma, incubated with [1-13C]glucose. After evolution to metabolic and isotopic steady states, the intracellular metabolites were extracted with perchloric acid. The specific enrichments of glutamate, aspartate and alanine carbons were determined from 13C-, 1H-NMR spectroscopy, or mass spectrometry data. Taking into account the rate of glucose consumption and of lactate formation, determined from the evolution of glucose and lactate contents in the cell medium, and knowing the activity of the hexose monophosphate shunt, it was possible to estimate the absolute values of all the considered fluxes. From the analysis the following results were obtained. (a) Glucose accounts for about 78% of the pyruvate and 57% of the CoASAc. (b) A metabolic channelling occurs at the citric acid cycle level; it favours the conversion of carbons 2, 3, 4, and 5 of 2-oxoglutarate into carbons 1, 2, 3, and 4 of oxaloacetate, respectively. The percentage of channelled metabolites amounts to 39%. (c) The pyruvate carboxylase activity and the efflux from the citric acid cycle are estimated to be very low, suggesting a lack of glutamine production in C6 cells. The results emphasize different metabolic characteristics of C6 cells when compared to astrocytes, their normal counterpart.

Alanine↗

PubMed1983

DNA concentrations in the human cerebellum. Computation from kinetics of deoxyribose extraction in hot acid.

DNA can be measured in mammalian tissues by extracting deoxyribose from unfixed, lyophilized tissue specimens with 0.5 N perchloric acid at 90 degrees C. Deoxyribose concentrations in the extract are determined photometrically by reaction with diphenylamine. Inevitably, some deoxyribose is destroyed during exposure to the hot acid. A computer program has been written which corrects photometric absorbance data for such loss of deoxyribose. When extrapolated to infinite duration of extraction, the corrected absorbances yield a measure of the DNA content of the specimen. This method was used to estimate DNA concentrations in human cerebellar cortex and white matter. The results are discussed in relation to stable carbon isotope ratios of human cerebellar DNA.

Cerebellar Cortex↗

PubMed1996

Evaluation of the importance of transamination versus deamination in astrocytic metabolism of [U-13C]glutamate.

Glutamate metabolism was studied in primary cultures of cerebral cortical astrocytes to determine the significance of transamination for the oxidative metabolism of glutamate. Cultures were incubated with [U-13C]glutamate (0.5 mM) in the presence and absence of the transaminase inhibitor aminooxyacetic acid (AOAA) and in some cases with methionine sulfoximine, an inhibitor of glutamine synthetase. Perchloric acid extracts of the cells as well as redissolved lyophilized incubation media were subjected to nuclear magnetic resonance spectroscopy to identify 13C-labeled metabolites. Additionally, biochemical analyses were performed to quantify amino acids, lactate, citrate, and ammonia. Glutamine released into the medium and intracellular glutamate were labeled uniformly to a large extent, but the C-3 position showed not only the expected apparent triplet but also a doublet due to 12C incorporation into the C-4 and C-5 positions. Incorporation of 12C into the C-4 and C-5 positions of glutamate and glutamine as well as labeling of lactate, citrate, malate, and aspartate could only arise via metabolism of [U-13C]glutamate through the tricarboxylic acid (TCA) cycle. Entry of the carbon skeleton of glutamate into the TCA cycle must proceed via 2-oxoglutarate. This conversion can occur as a transamination or an oxidative deamination. After blocking transamination with AOAA, metabolism of glutamate through the TCA cycle was still taking place since lactate labeling was only slightly reduced. Glutamate and glutamine synthesis from 2-oxoglutarate could, however, not be detected under this condition. It therefore appears that while glutamate dehydrogenase is important for glutamate degradation, glutamate biosynthesis occurs mainly as a transamination.

Amino Acids↗

PubMed1984

An enzyme specific method for estimation of pyruvic acid radioactivity in biological samples.

A method for the estimation of pyruvate radioactivity in complex biological samples is presented. After perchloric acid deproteinization, the samples were divided in two aliquots. All pyruvate was removed from the first aliquot with lactate dehydrogenase and NADH; the other was left undisturbed. Then all hydrophilic components of the sample were removed through an Amberlite XAD-7 column. The samples were treated with dinitrophenylhydrazine to obtain the corresponding hydrazones, which were retained in an Amberlite XAD-7 column and then were eluted with acetone and their radioactivity counted. The difference between both aliquots corresponded to the pyruvate radioactivity in the sample. No contamination by lactate, glycerol, glucose or amino acids was observed. The mean recovery of 5 determinations of pyruvate radioactivity was 91.3% +/- 1.0.

Acrylic Resins↗

PubMed1987

3-Hydroxy-3-methylglutaric, adipic, and 2-oxoglutaric acids measured by HPLC in the plasma from diabetic patients.

A method for the measurement of organic acids in human plasma is presented. The analytical procedure consists of plasma protein precipitation with acetonitrile, acid extraction by chromatography through a DEAE-cellulose column eluted with 100 mM perchloric acid, HPLC by cation-exchange column Aminex HPX-87 eluted with 6.5 mM sulfuric acid. Adipic, 3-hydroxy-3-methylglutaric, 2-oxoglutaric, and citric acids were determined in the plasma of diabetic patients. The concentrations of all the measured acids, but particularly those of adipic and 3-hydroxy-3-methylglutaric acids, were significantly higher than those of healthy controls. These results suggest that in diabetics the omega-oxidation of fatty acids is enhanced.

Adipates↗

PubMed1995

Investigation of decomposition products of microwave digestion of food samples.

The involatile residues remaining after closed-vessel microwave digestion of various food samples, using nitric acid, with and without post-digestion treatment with hydrogen peroxide, have been studied. Decomposition products were found to include aliphatic and aromatic acids, nitro-compounds, oxalates and inorganic nitrates and phosphates. Measures of digestion completeness were provided by appearance, carbon content, infrared spectra and thin layer chromatograms of the residues, enabling a comparison of different digestion methods and sample types. Residual carbon levels varied linearly with the relative amounts of carboxylic acid and inorganic nitrate, as measured by infrared spectrometry of the residues. The formation of calcium oxalate was also a function of the degree of decomposition: the carboxylic acid: oxalate ratio increased in a logarithmic fashion with increasing residual carbon content. Particularly high levels of residual carbon from nitric acid digestion of milk powder, due largely to carboxylic acid residues, were substantially decreased by post-digestion treatment with hydrogen peroxide. However, nitrobenzoic acids, which proved major interferents in electrochemical analysis, were only removed by treatment with perchloric acid.

Food↗

PubMed1999

Returning perchlorate-contaminated fume hood systems to service. Part II. Disassembly, decontamination, disposal, and analytical procedures.

Part I presented work leading up to and including a pilot study for remediation of laboratory fume hood systems contaminated with residues from processes that used fuming perchloric acid. Since publication of Part I, three incidents involving explosions and fires related to perchlorates have come to the attention of the authors. Experience has been gained through decontamination/remediation of 41 additional systems. This article expands on previous one and includes (1) administrative details that need to be addressed before and during the execution of the decontamination itself, (2) a seven-step procedure for decontamination-remediation/disposal, (3) some precautions associated with the use of methylene blue as a diagnostic tool for perchlorates, and-specific electrode to augment or replace the methylene blue test.

Air Pollutants, Occupational↗

PubMed1977

Leukocyte migration in ovarian carcinoma: comparison of inhibitory activity of tumor extracts.

Inhibition of migration of leukocytes from patients with serous cystadenocarcinoma of the ovary was studied by the use of several different types of ovarian carcinoma extract as antigen. KCl extract of an ovarian carconoma was found to be the most effective antigen preparation in comparison with saline, deoxycholate, and perchloric acid extracts. Low concentrations of KCl ovarian carcinoma extract significantly inhibited migration of leukocytes from 11 of 17 patients with ovarian carcinoma (migration index, less than 0.74). Leukocytes from patients with breast, colon, or endometrial carcinoma showed minimal reactivity with ovarian carcinoma KCl extract, and leukocytes from patients with ovarian carcinoma showed minimal reactivity with KCl extracts of breast, colon, and endometrial carcinoma. These results suggested that the 3 M KCl procedure is superior for the isolation of antigens active in the leukocyte migration inhibition test and that this test may be of use for the isolation of tumor-associated antigen and the immunodiagnosis of ovarian carcinoma.

Antibody Specificity↗

PubMed1982

Increased incorporation of an infused labelled amino acid into plasma proteins as a means of assessing the severity of injury or activity of disease in surgical patients.

Following injury there is increased synthesis of several plasma proteins. During a constant rate infusion of 1-(1-14C) leucine some of the labeled amino acid became incorporated into plasma proteins, the amount being readily determined after precipitation with perchloric acid. This value was correlated with the clinical state of the patient to see if an index of severity of injury could be derived. Before operation 6.7 +/- 0.5% (mean +/- SD, n = 16) of the infused labeled amino acid was incorporated in asymptomatic patients, irrespective of their dietary intakes, while in the presence of symptomatology this value rose, correlating with tumor staging in patients with colorectal neoplasia (r = 0.988, p = 0.001). It returned to normal following tumor resection, but was elevated in the presence of recurrence or residual disease. After operation it also rose, being maximal in the early postoperative period and following the more major surgical procedures, the increase correlating with the change in cortisol level in patients following cholecystectomy (r = 0.84, p less than 0.01; n = 8). The pattern of distribution of the label among the plasma proteins did not change with increased incorporation. The increase in incorporation of 1-(1-14C) leucine into plasma proteins would appear to offer a good index for severity of injury of activity of a disease state.

Blood Proteins↗

PubMed1979

[Comparative oxidation of erucic and oleic acids by mitochondria isolated from heart auricle of living man].

Mitochondria were isolated from fragments of heart auricles, that were cut off during surgical intracardiac operations. They were incubated with either [14 14C] erucic acid or [10 14C] oleic acid as a control. In the experimental conditions used, the radioactive products soluble in perchloric acid, that are issued from the beta-oxidation reactions in mitochondria, were formed in much lower amounts from erucic acid than from oleic acid. These results show the very low capacity of human heart mitochondria to use directly erucic acid as a substrate for energy requirements, as has been observed before with other animal species. Activation of fatty acids, the preliminary step of their beta-oxidation, was also observed to be very much lower with erucic acid.

Adult↗

PubMed1997

Towards the development of a bioartificial pancreas: a 13C NMR study on the effects of alginate/poly-L-lysine/alginate entrapment on glucose metabolism by beta TC3 mouse insulinoma cells.

We have utilized 13C NMR spectroscopy to investigate glucose metabolism in the mouse insulinoma Beta TC3 cell line. Cells were cultured and examined both as monolayers and entrapped in alginate/poly-L-lysine/alginate beads. Entrapped cultures were tested at 3 and 30 days post-entrapment. The purpose of this study was to assess whether the entrapped environment affects glucose metabolism and insulin secretion. Both monolayer and entrapped cultures were fed with 10 mM [1-(13)C]-glucose for 4 hrs. prior to extraction with perchloric acid. Our data revealed that beta TC3 cells possess a reduced tricarboxylic acid (TCA) activity in the entrapment cultures, and that they metabolized pyruvate primarily via pyruvate dehydrogenase regardless of the mode or age of the culture.

Alginates↗

PubMed1979

Studies on guinea-pig macrophage migration inhibitory factor (MIF). I. Glycoprotein nature and net charge.

Guinea-pig macrophage migration inhibitory factor (MIF), obtained by the stimulation of sensitized lymph node cells with tuberculin PPD, was characterized as a glycoprotein by the following criteria: (a) its activity is destroyed by 0.02 M sodium periodate; (b) when MIF-containing culture fluids are subjected to precipitation by perchloric acid (final concentration 1 M), the inhibitory activity is recovered in the supernatant; and (c) MIF binds to Sepharose-linked concanavalin A and can be eluted with methyl-alpha-D-glucopyranoside. When MIF-containing culture supernatants are fractionated by isoelectrofocussing, migration inhibitory activity is recovered in a fraction with an isoelectric point of 4.4--4.6.

Animals↗