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PubMedDate not supplied

Daily dietary intake of copper, zinc, and selenium of exclusively breast-fed infants of middle-class women in Burundi, Africa.

Copper (Cu), zinc (Zn), and selenium (Se) in human milk of middle-class Burundian women during the first 10 mo of lactation have been determined. Wet acid digestion, using nitric and perchloric acids, and atomic absorption spectrometric analysis have been used. Daily intakes have been calculated and proven to decrease from 0.39 +/- 0.05 (colostrum) to 0.16 +/- 0.02 (mature milk), 2.3 +/- 0.3 (colostrum), to 1.2 +/- 0.2 mg (mature milk) and 10.9 +/- 1.5 (colostrum) to 5.3 +/- 0.8 micrograms (mature milk) for Cu, Zn, and Se, respectively. Since values for this African country are nonexistent, intake levels are compared with literature data and found to be somewhat higher than those observed in other poorly nourished countries. The recommended safe and adequate daily intake for infants of 0-6 mo of age, as proposed by the National Research Council of the USA, is only met for Burundian infants < 1 mo of age. The function of copper (Cu) and zinc (Zn) as essential trace elements has been known for quite a number of years (1). Also, selenium (Se) is a trace element essential for the activity of glutathione peroxidase (2) and type I iodothyronine 5-deiodinase (3). For all three elements, an adequate intake is necessary for satisfactory infant growth and development (4). In view of the almost total lack of relevant data on Burundi (Africa), we have determined Cu, Zn, and Se in human milk of middle-class Burundian women during the first 10 mo of lactation (5). The aim of this study is to assess infants' elemental intake for this country and compare this with literature data on trace elemental intake of exclusively breast-fed infants.

Adult↗
PubMed1992

Decreased brain N-acetylaspartate in Huntington's disease.

The concentration of N-acetylaspartic acid (NAA) was measured in perchloric acid extracts of postmortem brain tissue obtained from patients with Huntington's disease and from control subjects. The material in the desalted extracts was resolved on an ion exclusion column and the content of NAA was determined by subsequent fluorometric quantitation of aspartate in hydrolyzates of the resolved NAA. The concentration of NAA in the putamen from patients with Huntington's disease was less than half that of controls (2.74 vs. 6.06 mumol/g wet weight). A smaller but significant reduction was also evident in samples of cerebral cortex from Brodmann area 10 (3.99 vs. 5.29 mumol/g), while the difference in concentrations in the cerebellum was not statistically significant. Though NAA could play a direct role in Huntington's disease, it seems more likely that the changes observed reflect illness or death of neurons, and that it may be feasible to monitor the course of Huntington's disease from NAA determinations. The same tissue extracts were also examined for the presence of D-isomers of amino acids. Only traces were found in NAA, aspartate, or glutamate.

Aspartic Acid↗
PubMed1977

Formylated bile acids: improved synthesis, properties, and partial deformylation.

Pure performylated bile acids are obtained in quantitative yield by a new formylation procedure. The procedure involves heating the bile acids in 90% formic acid containing catalytic amount of perchloric acid and then adding acetic anhydride slowly until effervescence occurs. Pure performylated bile acids are then isolated simply by diluting the reaction mixture with water. Contrary to what was believed by past investigations, the formyl groups on these compounds are quite stable to various reaction conditions. The stability and ready availability of these compounds make them more suitable candidates than their counterpart--bile acid acetates for use as starting material in various synthetic schemes, such as C-24 labeled bile acids, etc. The partial deformylation of these formates can be effected by using methanolic ammonia, sodium methoxide in methanol, or sodium hydroxide in aqueous acetone. The resultiing 3-hydroxy formyl bile acids are obtained in high yield and are the best starting materials for the synthesis of bile acids with specific modification at 3-hydroxyl group, such as the synthesis of bile acid 3-monosulfates and 3-monoglucuronides.

Acylation↗
PubMed2002

Analysis of dimeric cyanine-nucleic acid dyes by capillary zone electrophoresis in N,N-dimethylacetamide as non-aqueous organic solvent.

A method based on capillary zone electrophoresis is presented for the determination of the purity of commercial dimeric cyanine dyes (TOTO, YOYO, BOBO, all -1 and -3 species, LOLO-1, POPO-1) that are common as fluorescent probes for nucleic acid staining. These dyes are tetracharged cations, and have a strong tendency to interact with negatively charged centres, where they are rapidly adsorbed, especially from aqueous solutions. Thus anionic sites at the capillary wall must be avoided, and aqueous buffers are not suitable. The method introduced here avoids both complications, using non-aqueous N,N-dimethylacetamide as solvent, and suppressing the dissociation of silanol groups at the capillary surface due to selection of acidic separation conditions (20 mmol/l perchloric acid as background electrolyte). The present method enables the determination of the purity of all 10 dyes in less than 15 min. The selectivity of the method allows separation of at least five main and differentiating a number of unresolved minor contaminants as demonstrated in detail for TOTO-3 as an example. Quantitation (with 100% normalisation of the peak areas) of nine lots of this dye results in a purity between 33 and 87%.

Acetamides↗
PubMed1997

Metabolic alterations produced by 3-nitropropionic acid in rat striata and cultured astrocytes: quantitative in vitro 1H nuclear magnetic resonance spectroscopy and biochemical characterization.

Quantitative high resolution in vitro 1H nuclear magnetic resonance spectroscopy was employed to study the metabolic effects of 3-nitropropionic acid associated with aging from perchloric acid extracts of rat striata. Systemic injection of 3-nitropropionic acid in rats at a dose of 10 mg/kg/day for seven consecutive days significantly impaired energy metabolism in rats one, four and eight months of age, as evidenced by a marked elevation of succinate and lactate levels. However, a significant decrease in N-acetyl-L-aspartate level, a neuronal marker, was observed in four- and eight-month-old rats but not in one-month-old rats. This would indicate that rats at four to eight months are more susceptible to 3-nitropropionic acid than those at one month. A significant decrease in GABA level was observed in four-month-old 3-nitropropionic acid-treated rats, which is consistent with the literature that GABAergic neurons are particularly vulnerable to 3-nitropropionic acid treatment. In addition, glutamine and glutamate levels were markedly decreased at four and eight months in 3-nitropropionic acid-treated rats. Since glutamine is synthesized predominantly in glia, the observation above suggests that 3-nitropropionic acid intoxication may involve perturbation of energy metabolism, glial injury and consequent neuronal damage. Astrocytes which are essential in the metabolism of glutamate and glutamine were used to further assess 3-nitropropionic acid-induced toxicity. Glial proliferation, mitochondrial metabolism and glutamine synthetase activity were all reduced by 3-nitropropionic acid treatment with a concomitant increase, in a dose-dependent manner, of lactate levels, suggesting that 3-nitropropionic acid is also detrimental to astrocytes in vivo and thus may affect metabolic interaction between neurons and glia. These results not only imply that 3-nitropropionic acid blocks energy metabolism prior to exerting neurotoxic damage but also demonstrate that the degree of energy depletion determines the detrimental effects of 3-nitropropionic acid. In the present study, we also demonstrate that glutamate and glutamine levels as well as astrocytic functions may play pivotal roles in 3-nitropropionic acid-induced striatal lesions.

Animals↗
PubMed1990

Efficient large-scale purification of non-histone chromosomal proteins HMG1 and HMG2 by using Polybuffer-exchanger PBE94.

A method for the efficient and practical large-scale purification of high-mobility group (HMG) non-histone chromosomal proteins, HMG1 and HMG2, from porcine thymus applying Polybuffer-exchanger PBE94 gel as anion-exchanger has been developed. This method affords higher resolution, purity and yield, than the conventional procedure of CM-Sephadex C-25 ion-exchange column chromatography. Furthermore, use of Polybuffer-exchanger PBE94 column chromatography led to direct preparation of HMG1 and HMG2 from loosely bound non-histone chromosomal protein fraction of chromatin without prefractional precipitation with trichloroacetic acid or prior extraction with perchloric acid. Thus, the application of PBE94 gel as an anion-exchanger to the subfractionation of other kinds of homologous protein is possible.

Amino Acids↗
PubMed2003

Optimization of cellular nucleotide extraction and sample preparation for nucleotide pool analyses using capillary electrophoresis.

Cell extraction and further sample preparation for nucleotide pool analysis using capillary electrophoresis was faster and simpler using volatile extraction solvents (e.g. organic solvents and de-ionized water) compared to the commonly applied acids dissolved in water (e.g. perchloric acid and trichloracetic acid). Temperature had to be controlled during the whole sample preparation process to prevent degradation, and extracts had to be cleaned from proteins and other large molecules prior to capillary electrophoretic analysis to improve reproducibility. Capillary electrophoresis using borate and cyclodextrins in the background electrolyte was used for determining 11 cellular nucleotides simultaneously. In order to optimize the assay, 0-100% acetonitrile, 0-100% ethanol, and 0-100% methanol in de-ionized water were applied to extract nucleotides from mouse lymphoma cells, and nucleotide yields, recovery, and reproducibility were compared. The assay met the commonly accepted validation limits for biological fluids, if 20-80% acetonitrile in water and 40-60% ethanol in water were used as extraction solvents.

Acyclovir↗
PubMed2004

A general chemical route to polyaniline nanofibers.

Uniform polyaniline nanofibers readily form using interfacial polymerization without the need for templates or functional dopants. The average diameter of the nanofibers can be tuned from 30 nm using hydrochloric acid to 120 nm using perchloric acid as observed via both scanning and transmission electron microscopy. When camphorsulfonic acid is employed, 50 nm average diameter fibers form. The measured Brunauer-Emmett-Teller surface area of the nanofibers increases as the average diameter decreases. Further characterization including molecular weight, optical spectroscopy, and electrical conductivity are presented. Interfacial polymerization is shown to be readily scalable to produce bulk quantities of nanofibers.

Journal Article↗
PubMed1989

Simultaneous determination of ascorbic acid, caffeine and paracetamol in drug formulations by differential-pulse voltammetry using a glassy carbon electrode.

A simple, rapid and accurate method for the simultaneous determination of ascorbic acid, caffeine and paracetamol in drug formulations has been developed. Peak currents were measured with a glassy carbon electrode at +0.350, +0.618 and +1.425 V versus a saturated calomel electrode for ascorbic acid, paracetamol and caffeine, respectively. Perchloric acid (0.1 M) - methanol (1 + 1) was used both as a solvent and supporting electrolyte. The optimum modulation amplitude, pulse repeat time and scan rate of the polarographic analyser were found to be 50 mV, 0.5 s and 5 mV s-1, respectively and the linear calibration ranges for ascorbic acid, caffeine and paracetamol were 0-35, 0-50, and 0-55 micrograms ml-1, respectively. The relative standard deviations for 9.30 micrograms ml-1 of ascorbic acid, 8.50 micrograms ml-1 of caffeine and 7.30 micrograms ml-1 of paracetamol were 1.3, 2.5 and 0.7%, respectively. Results are reported for several commercially available drugs.

Acetaminophen↗
PubMed1998

Synthesis of fjord region tetraols and their use in hepatic biotransformation studies of dihydrodiols of benzo[c]chrysene, benzo[g]chrysene and dibenzo[a,l]pyrene.

Metabolic activation of the racemic benzo[c]chrysene-trans-9,10-, benzo[g]chrysene-trans-11,12- and dibenzo[a,l]pyrene-trans-11,12-dihydrodiols to fjord region syn- and anti-dihydrodiol epoxides by microsomes of Aroclor 1254-treated Sprague-Dawley rats has been examined. Since the fjord region dihydrodiol epoxides were hydrolytically unstable under the experimental conditions, their enzymatic formation was determined by analyzing the tetraols as their products of acidic hydrolysis upon addition of perchloric acid. The various stereoisomeric tetraols formed were separated by HPLC and identified by co-chromatography with authentic tetraols, which had been prepared by acidic hydrolysis of synthetically available syn- and anti-dihydrodiol epoxides and characterized by NMR and UV spectroscopy. Under standardized conditions the acidic hydrolysis of syn-dihydrodiol epoxides of benzo[c]chrysene, benzo[g]chrysene and dibenzo[a,l]pyrene resulted in the formation of two tetraols with cis/trans ratios of 81:19, 77:23 and 80:20, respectively, whereas the anti-dihydrodiol epoxides underwent almost exclusively trans hydrolysis. The proportion of the stereoisomeric tetraols obtained from microsomal incubations indicates that all three dihydrodiols are predominantly oxidized at the adjacent olefinic double bond to the anti-diastereomers of the corresponding fjord region dihydrodiol epoxides accounting for 4-35% of the ethyl acetate-extractable metabolites. To allow quantitative assessment of the metabolites 3H-labeled trans-dihydrodiols were synthesized by reduction of the corresponding o-quinones with sodium borotritide. Metabolic conversion of benzo[c]chrysene-trans-9,10- and dibenzo[a,l]pyrene-trans-11,12-dihydrodiol by rat liver microsomes were in a similar low range during the first 10 min of incubation (6.2 +/- 1.2 and 3.4 +/- 1.0 nmol substrate/nmol cytochrome P450/10 min, respectively), whereas the conversion of benzo[g]chrysene-trans-11,12-dihydrodiol was much higher (20.6 +/- 2.2 nmol substrate/nmol cytochrome P450/10 min). Given the strong intrinsic mutagenic and carcinogenic activity of the fjord region dihydrodiol epoxides, our data indicate that their formation, even at a relatively low level, may contribute significantly to the biological activity of the parent hydrocarbons.

Animals↗
PubMed1980

The extraction by micrococcal nuclease of glucocorticoid receptors and mouse mammary tumor virus DNA sequences is dissociated.

Glucocorticoid receptors (RG) and mammary tumor virus (MM-TV) DNA sequences were extracted by micrococcal nuclease digestion from the nuclei of C3H mouse mammary tumor cells in order to specify their relative distribution in chromatin. RG was labelled and translocated into the nuclei by incubating cells with 3H Dexamethasone (3H Dex). The purified nuclei were then treated at 2 degrees C with micrococcal nuclease. Three chromatin fractions were successively obtained: an isotonic extract (ne3H1), ahypotonic extract (ne2) and the residual pellet (P). The Dex-RG complexes were measured by the hydroxyapatite technique. The MMTV DNA sequences were titrated by molecular hybridization with an excess of MMTV radioactive cDNA probe. Up to 75% of the nuclear 3H Dex and the MMTV radioactive cDNA probe. Up to 75% of the nuclear 3H Dex and MMTV DNA sequences were extracted in a concentration dependent manner while only 10-15% of nucleic acids became soluble in 10% perchloric acid. The extracted 3H Dex-RG complex was found to be partly bound to soluble chromatin and partly free. The free complex displayed similar sedimentation constants (4S, 7S) and DNA binding ability to the cytosol receptor. The 3H Dex-RG complexes were 2 to 8 fold more concentrated in ne1, which is known to be enriched in active chromatin, than in ne2. Conversely, the concentration of MMTV DNA sequences per microgram DNA was the same in the three nuclear fractions. These results suggest that the Dex-RG complexes are concentrated in an active fraction of chromatin. We propose that, among the 20-30 copies of MMTV genes per haploid genome, only a small proportion are transcribed or regulated.

Animals↗
PubMed2002

The behaviour of 134Cs, 60Co, and 85Sr radionuclides in marine environmental sediment.

This work describes experimental investigations and modelling studies on the sorption of radionuclides 134Cs, 60Co, and 85Sr by certain marine sediments within Egypt. The chemical composition of the marine sediments was determined. The soluble salts were measured for the sediments and the concentrations of the released cations, Al3+, Fe3+, and Si4+, were measured for the sediment materials in 0.1 M NaClO4 aqueous solution at different hydrogen ion concentrations. The two main factors that control the uptake of the radionuclides onto the sediment are the pH and the exchangeable capacities of the sediment materials. Surface complex model was used to estimate the surface charge densities and the electric surface potential of the marine sediment materials. These two parameters were calculated at the surface capacity sites of the sediment materials. The desorption of the adsorbed cations was determined by means of selective consecutive extraction tests using different chemical reagents including (1) 1 M MgCl2 (pH 7), (2) 1 M ammonium oxalate (pH 3-5), (3) 0.04 M NH2OH,HCl in 25% acetic acid (pH 3-4), (4) H2O2 in 5% HNO3(pH 2-3), and (5) digestion with nitric acid followed by hydrofluoric and perchloric acids (pH 2).

Absorption↗
PubMed2002

Determination of vitamin C in plasma and dialysate from uremia patients by high performance liquid chromatography with electrochemical detection.

A convenient and valid method for the determination of ascorbic acid(AA) and dehydroascorbic acid(DHAA) in plasma and dialysate from patients with uremia by high performance liquid chromatography with electrochemical detection is described. A mixture of 0.8 g/L metaphosphoric acid and 18% (volume fraction) perchloric acid was used as a protein precipitant and the extractant for AA from biosamples. It was also a good stabilizer for AA in samples. The proposed method is satisfied for routine screening of vitamin C in clinical applications with a correlation coefficient of more than 0.99 in the range of 2 mumol/L-40 mumol/L AA. The within-day precision was less than 8.9% and 10.55% for AA and DHAA, respectively. The recoveries of AA in plasma and dialysate were over 95% and 78%, respectively.

Ascorbic Acid↗
PubMed2004

[Study on the determination of piperazinylethylestrone].

OBJECTIVE: To establish an HPLC method and a non-aqueous titration for the determination of piperazinylethylestrone drug substance, and an HPLC method for the determination of piperazinylethylestrone in dog plasma. METHODS: Anhydrous acetic acid as solvent, 0.1 mol/L perchloric acid as titrant, crystal violet solution as indicator to establish non-aqueous titrations and ODS column as stationary phase, methanol and a mixture of 0. 025 mol/L sodium phosphate monobasic and 0.02 mol/L sodium dedecyl sulfate (80:20) [adjusted with phosphoric acid to a pH (4.8 +/- 0.1)] as mobile phase, 220 nm as detective wavelength to establish HPLC-UV method for determination of piperazinylethylestrone drug substance; FMOC-CL as a derivatization reagent, FD as a detector to establish an HPLC method with derivatization and column switching for determination of piperazinylethylestrone in dog plasma. RESULTS: The RSD of non-aqueous titrations within-day and between-day were 0.28% and 0.21%, respectively; the established HPLC-UV method had good linearity and precision within the range of 1.001-5.005 microg of piperazinylethylestrone, the detection limit was 4 ng (S/N=3); the linearity of HPLC method with derivatization and column switching was within the range of 8.4-420 ng/ml, the detection limit was 1 ng (S/N=3). The clean-up recoveries were from 77.24% to 83.10%, and the method recoveries were 98.33%-103.3%. The RSD of within-day and between-day were less than 7.7% and 7.3%, respectively. CONCLUSION: The above three methods are simple, accurate and precise for the determination of piperazinylethylestrone drug substance and for the determination of piperazinylethylestrone in dog plasma.

Animals↗
PubMed1976

[Disadvantages of acid precipitation of proteins during the assay of blood glucose by the enzymatic glucose oxidase-peroxidase system].

In the enzymatic procedure for blood sugar by means of glucose oxidase, acid protein precipitation of blood by perchloric acid or trichloracetic acid liberated oxidizing substances, which enhanced the coloration density in oxidizing the reduced chromogen of the reaction mixture, independently of the hydrogen peroxide generated from glucose, and would give false high values of glycemia, if additional precautions had not been taken. These substances, increasing considerably with times and temperature of blood conservation, would be of peroxide nature, and would accumulate in red blood cells during their exposure to air.

Animals↗
PubMed1986

Effects of the blocking agents bovine serum albumin and Tween 20 in different buffers on immunoblotting of brain proteins and marker proteins.

The effects of the blocking agents bovine serum albumin and Tween 20 in buffers at pH values 7.2 and 10.2 were compared in immunoblotting with 2 different antisera. The antisera were raised against a purified brain-specific protein fraction from human brain, soluble in perchloric acid, and phosphate-activated glutaminase from pig brain, respectively. The antigens were a crude perchloric acid-soluble brain extract, a crude brain phosphate-activated glutaminase fraction, and proteins commonly used as molecular weight markers. The binding patterns of the 2 antisera to the respective brain antigen preparations changed, depending on the blocking agent and the pH of the blocking buffer. Also, antibody binding to the molecular weight marker proteins was observed with some of the blocking buffers. Immunoblotting with Tris-saline, pH 10.2, containing 3% bovine serum albumin as blocking agent and diluting buffer for the antisera, showed negligible antibody binding to the marker proteins and most specific binding to the brain antigens.

Brain↗
PubMed1976

A method for enzymatic determination of citrate in serum and urine.

A method for determination of citrate in serum and urine using citrate lyase is described. The influence of pH, zinc, magnesium, and calcium ions on the reaction velocity is studied. Citrate lyase activity is found rather insensitive to variations in pH round the pH-optimum at 8.2. Zinc ions activate the reactions. The optimal concentration of zinc ions in the reaction mixture is found to depend on the calcium concentration of samples. Perchloric acid is used for precipitation of proteins. The perchloric ion inhibits the reaction, and a procedure for removing perchlorate is given. Sensitivity of analysis is 0.005 mmo1/1 for serum and urine samples, respectively. No contamination of citrate lyase is found, and therefore addition of lactate dehydrogenase is considered unneccessary.

Calcium↗