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At least 343 records · Page 19Linked to original sources
PubMed1980

A direct competitive binding radioimmunoassay for carcinoembryonic antigen.

We have incorporated commercially available CEA standard and antiserum into the triple isotope double antibody radioimmunoassay and we have evaluated this assay for the routine determination of CEA. The competitive protein binding (CPB) assay for CEA can be performed directly on serum or plasma without perchloric acid extraction. The assay sensitivity was 0.98 ng/ml, and the day-to-day precision as defined by the coefficient of variation was 12.5% and 13.3% for mean values of 7.6 and 23.9 ng CEA/ml, respectively. The normal range (X +/- 2 S.D.) for CEA determined with the direct CPB method was 3.2--6.2 ng CEA/ml for non-smokers. The upper limit of normal for smokers was 10.0 ng/ml. A method comparison study (Roche perchloric acid extraction vs. direct CPB) showed excellent agreement between the methods for plasma samples containing less than 20.0 ng CEA/ml. The least square analysis parameters were: N = 116, slope = 1.01, y-intercept = 3.5 ng/ml, Sy/x -2.05 ng/ml, and the correlation coefficient was 0.79. Recovery and dilution studies showed no demonstrable non-specific interference due to serum proteins in the direct CPB assay. The clinical significance of the direct CPB assay for CEA was assessed by correlating serial CEA values with the clinical status of patients with breast and colorectal cancer. Increasing CEA values correlated with progressive or recurrent neoplastic disease, and decreasing CEA values correlated with response of the patient to therapy. No false positive direct CPB values for CEA were observed in the clinical study or in the method comparison study. Our laboratory and clinical evaluation demonstrate that the direct CPB method is an accurate and reliable method for the quantitation of CEA. In addition, the method permits high volume analysis and eliminates the hazards to safety that are associated with perchloric acid.

Binding, Competitive↗
PubMed1983

Degradation study of catecholamines, indole amines and some of their metabolites in different extraction media by chromatography and electrochemical detection.

Optimal conditions for the extraction from brain tissue and the simultaneous quantification of catechol and indole derivatives were determined after a systematic degradation study in water and perchloric acid. The roles of three parameters, namely temperature, presence of antioxidant agents, and time, were considered. Adrenaline, noradrenaline, dopamine, homovanillic acid, 5-hydroxytryptophan, 5-hydroxyindole acetic acid, serotonin, and epinephrine were separated by HPLC and detected electrochemically. The results indicated a great instability of the indole derivatives at an ambient temperature, in an acid medium, and in the absence of a protective agent. Therefore, when perchloric acid has to be used for deproteinization, the lowest concentration (0.1 M) is preferable. The samples have to be kept on ice, in darkness, and protected by ascorbic acid and sodium ethylenediamine tetracetate.

Ascorbic Acid↗
PubMed1986

Quantitative and qualitative characterization of human cancer-associated serum glycoprotein antigens expressing fucosyl or sialyl-fucosyl type 2 chain polylactosamine.

The quantity of tumor-associated antigens carrying type 2 chain polylactosamines with four types of fucosyl determinants, LeX (X-hapten), poly-LeX, sialyl LeX, and LeY (Y-hapten), present in sera of patients with various malignant and non-malignant disorders, as well as the qualitative chemical properties of the carrier molecules in sera, have been investigated using four monoclonal antibodies, each of which defines one of these determinants. The following findings are of particular importance: the serum levels of LeX defined by antibody FH2 and poly-LeX defined by ACFH18 in patients with cancer were occasionally high (incidence about 10%); however, the majority of patients did not show elevated levels; the serum level of the antigen, defined by monoclonal antibody FH6 (termed sialyl LeX-i since this determinant is carried by i antigen), was significantly high in patients with cancers originating from organs from which adenocarcinomas often develop. For example, among various types of lung cancer, only adenocarcinoma but not squamous cell carcinoma, small cell carcinoma, or large cell carcinoma showed a high level of sialyl LeX-i antigen in sera. The incidence of high antigen levels in sera of patients with adenocarcinomas of lung was as high as 76% of the observed cases; the serum level of Ley (Y-hapten) was frequently high in patients with hepatoma (incidence, 34%); sialyl LeX-i antigen was separated on gel filtration as a glycoprotein with an average molecular weight greater than 10(6). It was characterized by its susceptibility to basehydrolysis, Pronase digestion, and sialidase and endo-beta-galactosidase treatment and is assumed to be a high molecular weight mucin-type glycoprotein; sialyl LeX-i antigen expressed in sera of patients with cancer was soluble in perchloric acid, while the same antigen in sera of patients with noncancerous diseases and normal subjects was mostly insoluble in perchloric acid. LeX, a poly-LeX, and essentially all LeY antigens in sera of patients with cancer were perchloric acid-insoluble.

Antibodies, Monoclonal↗
PubMed1988

High-performance liquid chromatographic measurement of selected blood citric acid cycle intermediates.

We describe a high-performance liquid chromatographic (HPLC) method for analysis of the intermediates of the citric acid cycle. Using two Aminex HPX-87H columns in series at 36 degrees C, the early eluting compounds cis-aconitate, oxaloacetate, alpha-ketoglutarate and citrate-isocitrate can be resolved. Acetonitrile is used for extraction of citric acid cycle intermediates from blood as interfering ultraviolet absorbing peaks are present with perchloric acid or trichloroacetic acid extraction. Acetonitrile extraction is compared with perchloric acid extraction of citric acid cycle intermediates from plasma. Low recovery of some organic acids from blood seems not to be due to enzymatic degradation. Storage of acetonitrile extracts in liquid nitrogen led to a small but significant decrease in pyruvate levels in human blood. However, significant changes in other organic acids were not seen. HPLC methodology allows study of the citric acid cycle in tissue samples as well as blood and promises to facilitate the investigation of human disorders of energy metabolism.

Acetonitriles↗
PubMed1978

Spectrophotometric determinations of 3-dimethylaminomethylkhellin hydrochloride and khellin.

Spectrophotometric assays are proposed for the determination of 3-dimethylaminomethylkhellin hydrochloride and khellin in bulk chemical and dosage forms. The acid dye method, using methyl orange at pH5, is applied to assay the amine in the form of an ion-pair extractable in chloroform with maximum abosrbance at 420 nm. The perchloric acid method, depending on formation and extraction of the oxonium salts of both compounds, is used to assay the amine and khellin at 333 or 430 nm and at 325 or 410 nm, respectively. The reineckate method can be used to assay the amine as the reineckate derivative in acetone with maximum absorbance at 530 nm. However, small amounts of the amine (1.5--3 mg) can be determined as the reineckate in methanol with maximum absorbance at 245 nm. Stability determination of the two compounds can be done by the acid dye and perchloric acid methods. The three methods are sufficiently accurate, sensitive, and precise.

Drug Stability↗
PubMed1991

Improved ion-pair high-performance liquid chromatographic method for the quantification of a wide variety of nucleotides and sugar-nucleotides in animal cells.

An improved method including extraction procedures is presented for the analysis of nucleotides in suspension-cultivated animal cells. Quantification was performed by ion-pair high-performance liquid chromatography after perchloric acid extraction. It was found that the amount of perchloric acid taken for extraction influenced the yield and that cell washing procedures caused deterioration of the analysis results for triphosphates. More than thirty nucleotides and sugar-nucleotides were separated within 25 min using a Supelcosil reversed-phase column (3 microns) with tetrabutylammonium hydrogensulphate as pairing agent and methanol-pH gradient elution. Cultivated hybridoma cells showed variations in intracellular nucleotide concentrations as well as relative amounts during different growth phases, which could reflect the physiological state of a cell culture.

Adenosine Triphosphate↗
PubMed2005

Removal of lead ions in drinking water by coffee grounds as vegetable biomass.

In an attempt to reuse food waste for useful purposes, we investigated the possibility of using coffee grounds to remove lead ions from drinking water. We studied the lead ion adsorption characteristics of coffee beans and grounds by measuring their fat and protein content, adsorption isotherms for lead ions, and adsorption rates for lead ions. The number of lead ions adsorbed by coffee grounds did not depend on the kind of coffee beans or the temperature at which adsorption tests were performed. The rate of lead ion adsorption by coffee grounds was directly proportional to the amount of coffee grounds added to the solution. When coffee grounds were degreased or boiled, the number of lead ions decreased. When proteins contained in coffee grounds were denatured, the lead ion adsorption was considerably reduced. The lead ion adsorption capacity of coffee grounds decreased with increased concentration of perchloric acid used for treating them and disappeared with 10% perchloric acid. The experiments demonstrated that proteins contained in coffee beans depend upon the adsorption of lead ion. The present study gave an affirmative answer to the possibility of using coffee grounds, an abundant food waste, for removing lead ions from drinking water.

Adsorption↗
PubMed1985

Gas chromatography-mass spectrometry of carboxylic acids in tissues as their tert.-butyldimethylsilyl derivatives.

Krebs cycle and related acids were isolated from liver, pancreas and stomach of rats by pulverizing frozen tissue samples in liquid nitrogen with an aqueous solution of perchloric acid and methoxylamine hydrochloride. Perchloric acid and basic and neutral compounds were removed by ion-exchange chromatography on DEAE-Sephadex and SP-Sephadex columns. Phosphate was removed without loss of citrate by partition chromatography on Sephadex G-25 in a butanol--water system. Loss of acids during evaporation of water was prevented by keeping the temperature low and by addition of ammonia and tetrabutyl-ammonium bromide. tert.-Butyldimethylsilyl derivatives were prepared, purified by chromatography on a Sephadex LH-20 column and separated by gas chromatography on a non-polar capillary column. Recoveries in the procedure were above 45% for all acids except acetoacetate (25%). The mass spectrometric fragmentation of the methoxime-tert.-butyldimethylsilyl derivatives was studied by analysis of the derivatives of deuterated acids. The intense ions at M-57 present in all spectra appeared to contain all original hydrogen atoms. Thus, the method should be suitable for quantitation by isotope dilution and in metabolic studies with deuterated compounds.

Animals↗
PubMed1991

The influence of assay conditions on measurement of excitatory dibasic sulphinic and sulphonic alpha-amino acids in nervous tissue.

Major improvements to the HPLC separation of fluorescent derivatives of excitatory sulphur-containing amino acids have been made. Quisqualate was used as the internal standard since no endogenous derivatives coeluted with it. The artefactual generation of sulphinic and sulphonic amino acids from the oxidation of cysteine (56 microM) and homocysteine (1.2 microM) has been investigated using deionised water, an acidic phosphate/methanol mixture, perchloric acid and trichloroacetic acid (TCA) as extraction media. Of the four extraction media examined, TCA in combination with ether extraction was shown to be the most potent oxidative treatment and resulted in 23% oxidation of original cysteine or homocysteine to sulphinic and sulphonic acids. This oxidation was partially resistant to the presence of physiological concentrations of glutathione (1.5 mM) such that in the case of cysteine, 6% oxidation was observed. A 10% (v/v) mixture of methanol in 75 mM phosphate solution (pH 4.6) was found to be the most artefact-free extraction method and in spinal cord tissue processed with this medium, cysteine sulphinic acid was the only excitatory sulphur-containing amino acid consistently detectable (0.24 +/- 0.01 pmol/mg wet weight, n = 6).

Amino Acids, Sulfur↗
PubMed1978

A comparison of methods for the isolation of carcinoembryonic antigen.

Carcinoembryonic antigen (CEA) was isolated from a human tumor with 0.02 M sodium phosphate containing 0.14 M NaCl (pH 7.0) (saline) and further studied after treatment with perchloric acid or 8 M urea. Preparations CEA obtained from saline homogenates and both methods of treatment were characterized by isoelectric focusing and gel filtration. Perchloric acid treatment resulted in an approximate 10-fold decrease in protein and a significant loss of CEA as compared to the saline- and urea-treated material. Isoelectric focusing revealed that the resultant CEA subpopulations were dependent upon the method of isolation. Urea- and saline-treated material showed complex isoelectric patterns that were quantitatively dissimilar. Perchloric acid-treated material showed a comparatively simple isoelectric pattern that was not significantly affected by electrofocusing in the presence of urea. Gel filtration on ACA 34 of the CEA obtained from each method of isolation resulted in two peaks of activity. The first peak corresponded to the void volume of the column, and the second peak coeluted with commercially available purified 125I-labeled CEA. Centrifugation of the peaks obtained resulted in a significantly greater loss of CEA from the void peak of each isolation procedure. The amount of CEA lost from the void peaks following centrifugation differed with each method of isolation and suggested the presence of aggregates.

Carcinoembryonic Antigen↗
PubMed1985

Lipid composition of different areas of murine brain: effects of lipid extraction procedures.

The effects of various chemical extraction procedures on the determination of lipid composition of rat and mouse brain have been investigated. Tissue extractions with formic acid/acetone or perchloric acid both resulted in significant losses of total phospholipids and cholesterol. Perchloric acid extraction also degraded, almost quantitatively, ethanolamine plasmalogens to lysophosphatidylethanolamine. Our findings have thus demonstrated that conventional procedures used for extraction of brain tissue for analysis of choline and acetylcholine content cannot also be used for concurrent/simultaneous extraction of phospholipids and cholesterol from the same tissue.

Animals↗
PubMed1975

The isolation of nuclei and basic nucleoproteins from the cellular slime mold Dictyostelium discoideum.

A method is described for the isolation of nuclei from an axenic strain of Dictyostelium discoideum using a sorbitol/Ficoll solution and low concentration of Triton X-100. Basic proteins have been extracted from the nuclei and on polyacrylamide gel electrophoresis yield a consistent pattern in which five major groups or bands predominate. Four of these five fractions comigrate with calf thymus histones and one fraction seems to be unique to D. discoideum. The slowest moving of the five fractions is soluble in 0.5 M perchloric acid and comigrates with calf thymus histone F1. After recovery from the perchloric acid solution by precipitation with acetone this fraction yielded one major band on electrophoresis.

Animals↗
PubMed1975

Solvolytic reactions of cyclic anhydrides in anhydrous acetic acid.

The reversible reactions of several cyclic anhydrides with acetic acid to form acetic anhydride and the corresponding dicarboxylic acid, catalyzed by perchloric acid at 25degree, were studied. The equilibrium constants, calculated from spectral data, were 4.85 X 10-4, 1.08 X 10-1, and 4.6 X 10-1 M for succinic, trans-1,2-cyclohexanedicarboxylic, and glutaric anhydrides, respectively. Maleic, phthalic, and cis-1,2-cyclohexanedicarboxylic anhydrides did not undergo any detectable reaction with acetic acid under these conditions, suggesting still higher stability. The reverse rate constants were found to be relatively independent of the structure of the attacking diacid, while the forward rate constants were found to parrallel the equilibrium constants. The rate-determining step for the forward reaction appears to be the breakdown of the tetrahedral intermediate formed by the attack of an acetic acid molecule on the protonated cyclic anhydride.

Acetates↗
PubMed1984

Leukopenia with different regenerated haemodialysis membranes.

The white blood cell count (WBC) decreases during haemodialysis and it was investigated as a function of different dialysis membranes. Each of them was used four times, applying different sterilization methods. Twelve chronic haemodialysis patients were studied and dialysed with cuprophan and polyacrylonitrile (PAN) membranes. Cuprophan was studied by a dry sterilization method and after perchloric acid and formalin treatment. PAN was studied with dry sterilization and after perchloric acid. As it has been shown, cuprophan membranes cause significantly more marked neutropenia than PAN. No significant difference was seen in pO2, pH, pCO2 and bicarbonate between dialysers used four times. The results indicate differences in biocompatibility between cuprophan and PAN membranes, independent of the sterilization method employed.

Acrylic Resins↗
PubMed1992

Simultaneous determination of allantoin and oxypurines in biological fluids by high-performance liquid chromatography.

A high-performance liquid chromatographic method is described for the separation and quantification of allantoin and oxypurines in plasma and urine samples. Urine was analyzed directly and plasma after acid deproteinisation with perchloric acid. Separation and quantification of purine derivatives was achieved using two Spherisorb ODS-5 column (250 mm x 4.6 mm I.D.) connected in series together with a NH4H2PO4-NH4H2PO4-acetonitrile (80:20) gradient and monitoring the effluent at 205 nm. The average recoveries of standard compounds added to urine and plasma samples were 96 and 97%, respectively, using allopurinol as internal standard. The within-day variability was less than 7% and the day-to-day coefficient of variation less than 11% indicating a good precision of the method.

Allantoin↗
PubMed1995

Determination of manganese in human brain samples.

A method is presented for the determination of manganese (Mn) in human tissue samples (especially brain) by graphite furnace atomic absorption spectrophometry (GFAAS). After complete digestion by a mixture of concentrated nitric acid (HNO3)/concentrated perchloric acid (HClO4) (50:50, v/v), the samples are assayed on a Perkin-Elmer 5100 PC apparatus, equipped with transversal graphite tubes and a Mn-specific hollow cathode lamp. The furnace conditions are as follows (for each step: temperature (degree C)/ramp (s)/duration (s)) dry 120/1/40; char 1200/5/10; atomization 2250/0/4; pyrolysis 2400/1/1. Zeeman correction is employed. The method is linear over the range 0.05 to 5.00 micrograms/g wet tissue, and the limit of detection for Mn is about 0.01 microgram/g wet tissue. This simple and rapid method may be of value for the post-mortem assessment of Mn accumulation in brain structures due to occupational or iatrogenic exposure. An application is presented in which elevated levels of Mn were determined in the brain samples of a 63-year-old female deceased after long-term total parenteral nutrition involving Mn supplementation.

Brain Chemistry↗
PubMed1985

Reversed-phase liquid chromatographic investigation of nucleosides and bases in mucosa and modified nucleosides in urines from patients with gastrointestinal cancer.

Reversed-phase high-performance liquid chromatography (HPLC) has been used to determine the level of nucleic acid metabolites in perchloric acid extracts of gastrointestinal mucosa. By comparing the levels of these compounds in the normal portion with the levels in the neoplastic portion of mucosa resected from patients with malignant cancer, it was found that uracil was significantly elevated in the neoplastic colorectal mucosa (adenocarcinoma) of eight patients with colorectal cancer (P less than 0.01, statistically significant with the paired t test). The mean level of uracil in neoplastic colorectal mucosa was 2.7-fold higher than that in normal mucosa. However, in neoplastic gastric mucosa, only one out of four patients with gastric cancer showed elevated uracil. In neoplastic mucosa, the levels of hypoxanthine and uridine for colorectal cancer, and inosine for gastric cancer, were also significantly higher than those in normal mucosa (P less than 0.05, with the paired t test). The urinary modified nucleosides were prefractionated with a boronate affinity gel column, and their levels determined by the same HPLC method. No significant differences in the concentrations of pseudouridine, 1-methylguanosine, N2-methylguanosine or N2,N2-dimethylguanosine were observed in pre- and post-operative urines from patients with colorectal cancer and normal urines.

Chromatography, Affinity↗