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PubMed1995

Elimination of paraprotein interference in determination of plasma inorganic phosphate by ammonium molybdate method.

Phosphate concentrations were determined in 52 cases of paraproteinemia. The unmodified acidic ammonium molybdate method produced 19% spuriously high results. The false increase of phosphate concentration was attributable to formation of precipitate in the reaction mixture. The precipitate was formed by interaction between immunoglobulins and the unmodified acidic ammonium molybdate reagent. The magnitude of interference bore no relation to the type, concentrations, or isoelectric point of the paraproteins or to the presence or absence of free light chains. Diluting the sample to approximately 40 g/L total protein reduced but did not always eliminate the interference. In some cases paraprotein concentration as low as 8 g/L falsely increased plasma phosphate results. Apparently, only IgG and IgM but not IgA paraproteins produced the interference. Deproteination by ultrafiltration or by treatment with trichloroacetic acid removed the interference. The Kodak slide method and the new modified Boehringer Mannheim phosphate test were found to be interference-free. However, in some cases the latter new formulation is sensitive to substantial changes in ionic concentration of the reaction mixture.

Ammonium Sulfate↗

PubMed1999

Direct electron transfer for hemoglobin in biomembrane-like dimyristoyl phosphatidylcholine films on pyrolytic graphite electrodes.

Stable thin films made from dimyristoyl phosphatidylcholine (DMPC) with incorporated hemoglobin (Hb) on pyrolytic graphite (PG) electrodes were characterized by electrochemical and other techniques. Cyclic voltammetry (CV) of Hb-DMPC films showed a pair of well-defined and nearly reversible peaks at about -0.27 V vs. saturated calomel electrode (SCE) at pH 5.5, characteristic of Hb heme Fe(III)/Fe(II) redox couple. The electron transfer between Hb and PG electrodes was greatly facilitated in DMPC films. Apparent heterogeneous rate constants (ks) were estimated by fitting square wave voltammograms of Hb-DMPC films to a model featuring thin layer behavior and dispersion of formal potentials for redox center. The formal potential of Hb heme Fe(III)/Fe(II) couple in DMPC films shifted linearly between pH 4.5 to 11 with a slope of -48 mV pH-1, suggesting that one proton is coupled to each electron transfer in the electrochemical reaction. Soret absorption band positions suggest that Hb retains a near native conformation in DMPC films at medium pH. Differential scanning calorimetry (DSC) showed the phase transition for DMPC and Hb-DMPC films, suggesting DMPC has an ordered multibilayer structure. Trichloroacetic acid (TCA) was catalytically reduced by Hb-DMPC films with significant decreases in the electrode potential required.

Algorithms↗

PubMed1976

Determination of growth of Sphaerotilus discophorus in the presence of manganese.

Manganese interferes strongly with most chemical methods of biomass determination. However, the biomass of manganese-encrusted Sphaerotilus discophorus can be determined after removal of the MnO2 with trichloroacetic acid and oxalic acid. Evidence which indicates that manganese inhibits the heterotrophic growth of S. discophorus and that the cells only oxidize manganese late in the growth curve is presented.

Bacterial Proteins↗

PubMed1990

Determination of tin in biological samples using gaseous hydride generation-inductively coupled plasma-atomic emission spectrometry.

A highly sensitive method determining for sub-microgram/gram levels of tin in biological samples is described. Tin hydride reduced by sodium borohydride and trichloroacetic acid solution was introduced into inductively coupled plasma after separation of liquid and excess hydrogen by an improved gas/liquid separator, and emission intensity was measured at a wavelength of 189.989 nm. Samples were decomposed by a nitric acid-perchloric acid mixture and analyzed after dilution by a standard addition technique. The relative standard deviation was 1.2% for a 10 ng/ml tin standard solution with a detection limit of 30 pg/ml.

Animals↗

PubMed1991

Uptake and subcellular localization of tritiated dihydro-microcystin-LR in rat liver.

Microcystin-LR (MC-LR), a cyclic heptapeptide hepatotoxin (mol. wt = 994) produced by the blue-green alga (cyanobacterium), Microcystis aeruginosa, was reduced with tritium labeled sodium borohydride, converted to [3H]-dihydro-microcystin-LR ( [3H]-2HMC-LR), and purified to greater than 99% purity by C-18 reverse-phase high-performance liquid chromatography. The uptake and subcellular distribution of [3H]-2HMC-LR were determined in suspensions of hepatocytes at 0 degrees C and 37 degrees C, or following rifampicin pretreatment, and in perfused rat liver. The remaining cells were homogenized and subfractionated using sucrose gradient centrifugation. Suspensions of 7.5 x 10(6) hepatocytes also were incubated with 10 micrograms/ml of toxin, solubilized in Triton X-100, and ultracentrifuged to pellet the detergent insoluble fraction (containing actin). Isolated rat livers were perfused with media containing [3H]-2HMC-LR and the uptake of radiolabel was determined. Sequential biopsy samples were collected for histologic examination. The remaining liver was homogenized and subcellular fractions prepared. Uptake of radiolabel was rapid in both cell suspension at 37 degrees C and perfused liver; however, uptake in cell suspensions was reduced by about 50% at 0 degrees C and by rifampicin (50 micrograms/ml) pretreatment. Hepatocyte necrosis was observed in isolated perfused livers 45 min after initiation of perfusion with [3H]-2HMC-LR. In both hepatocyte suspensions and perfused livers 65 to 77% of the radiolabel was in the cytosolic fraction. In the hepatocyte suspensions, 13 to 18% of the radiolabel was present in the plasma membrane/nuclear fraction with lesser amounts in the other fractions. Trichloroacetic acid treatment of cytosolic fractions indicated that in hepatocyte suspensions, 50-60% of the radiolabel was bound to cytosolic protein. Studies using the perfused liver confirmed that the majority of the radiolabeled MCLR (78-88%) was bound to cytosolic protein. These data suggest that the uptake of [3H]-2HMC-LR occurs primarily by an energy-dependent transport process involving the rifampicin-sensitive hepatic bile acid carrier and that once inside the hepatocyte, the toxin binds to a cytosolic protein(s).

Animals↗

PubMed1996

Transconjunctival blepharoplasty with chemoexfoliation.

Transcutaneous blepharoplasty has been the standard for improving the overall appearance of the lower eyelid, as it addresses skin, muscle, and pseudoherniated orbital fat. Postoperative problems, including poor scarring, scleral show, and even frank ectropion, have led many surgeons to alternate techniques. Transconjunctival blepharoplasty is known to be a reliable method of removing lower eyelid fat, but has been touted as inadequate for those possessing excessive skin and has even been cited as being responsible for increasing lower eyelid wrinkling. Chemoexfoliation, utilizing trichloroacetic acid and phenol, was performed simultaneously with transconjunctival blepharoplasty in 146 patients, whose data are retrospectively reviewed. Excellent results were obtained in lower eyelid skin appearance and pseudoherniated fat in the majority of patients, without an external lower eyelid scar.

Chemexfoliation↗

PubMed2001

The effects of alpha-lactabumin and whey protein concentrate on dry matter recovery, TCA soluble protein levels, and peptide distribution in the rat gastrointestinal tract.

The effects of two dietary proteins on dry matter recovery, trichloroacetic acid (TCA) soluble protein concentration, and peptide distribution in gastrointestinal contents were investigated in rats trained to consume, in a single 2-hour daily meal, diets containing alpha-lactalbumin (alpha-LA) or whey protein concentrate (WPC) for two weeks. Compared with the WPC diet, the alpha-LA diet emptied faster from the stomach. Dry matter recovery was higher in the stomach contents of rats fed the WPC diet than in those given the alpha-LA diet, but dry matter content in the small intestine was comparable. TCA soluble protein levels in the stomach and the small intestinal contents were also significantly (P < 0.001) higher in rats fed the WPC diet. The concentration of peptides having molecular weights (MW) ranging from 12,500-30,000 daltons (Da) was higher in the stomach contents of rats fed the WPC diet. Conversely, the level of peptides ranging from 5000-12,500 Da was higher in the stomach contents of rats fed the alpha-LA diet. For both diets, the small intestinal contents were characterized by high levels of amino acids and small peptides. These results suggest that the hydrolysis and absorption of alpha-LA is faster than that of WPC.

Animals↗

PubMedDate not supplied

Biliary excretion of trichloroethylene and its metabolites in dogs.

To examine the biliary excretion of trichloroethylene (TRI) and its metabolites, we carried out various experiments with TRI and its metabolites, i.e., chloral hydrate (CH), free-trichloroethanol (F-TCE) and trichloroacetic acid (TCA), using anesthetized dogs. The amount of biliary excretion was significantly increased with the administration of CH and F-TCE, whereas it remained at control levels with the administration of TRI and TCA. The substances excreted into bile were conducted in the form of conjugated-TCE (Conj-TCE) in over 90% of the CH, F-TCE and TRI administration groups. About 95% of these Conj-TCE were conjugated with glucuronic acid. The cumulative excretion ratios of substances and metabolites to dose were 20% for CH and F-TCE, and about 1% for TCA and TRI 2 h after administration.

Animals↗

PubMed2002

Electrochemistry and electrocatalysis with heme proteins in chitosan biopolymer films.

Protein-chitosan (CS) films were made by casting a solution of proteins and CS on pyrolytic graphite electrodes. Myoglobin (Mb), hemoglobin (Hb), and horseradish peroxidase (HRP) incorporated in CS films gave a pair of stable, well-defined, and quasi-reversible cyclic voltammetric peaks at about -0.33V vs saturated calomel electrode in pH 7 buffers, respectively, while catalase (Ct) in CS films showed a peak pair at about -0.46V which was not stable. All these peaks are located at the potentials characteristic of heme Fe(III)/Fe(II) redox couples of the proteins. The electrochemical parameters such as formal potentials (E degrees (')) and apparent heterogeneous electron-transfer rate constants (k(s)) were estimated by square-wave voltammetry with nonlinear regression analysis. Chitosan films contained considerable water and formed hydrogel in aqueous solution. Positions of the Soret absorbance band suggest that Mb and Hb in CS films keep their secondary structure similar to the native states in the medium pH range, while HRP and Ct retain their native conformation at least in the dry CS films. Scanning electron microscopy of the films demonstrated that interaction between the proteins and CS would make the morphology of dry protein-CS films very different from the CS films alone. Oxygen, trichloroacetic acid, nitrite, and hydrogen peroxide were catalytically reduced by all four proteins in CS films.

Animals↗

PubMed1979

Determination of cefatrizine in serum and urine by reversed-phase high-performance liquid chromatography.

A fast and simple high-performance liquid chromatographic procedure for the determination of cefatrizine, an orally active cephalosporin, in serum and urine is proposed. Reversed-phase liquid chromatography on the octoadecylsilane chemically bonded microparticulate packing, using methanol in 0.03 M sodium phosphate buffer (pH 5) as eluent, was used to separate and quantitate the antibiotic. The samples were analysed after deproteinization with trichloroacetic acid and injection of the clear supernatant. The accuracy and reproducibility of the procedure were investigated by determination of the cefatrizine content in spiked serum and urine samples, using cephradine as the internal standard.

Cefatrizine↗

PubMed1995

Noncervical human papillomavirus genital infections.

The incidence of human papillomavirus infection is increasing. More than 60 types of human papillomavirus have been isolated; some types are known to have malignant potential. Differential diagnosis of the lesions includes condyloma latum, seborrheic keratoses, nevi, pearly penile papules and neoplasms. The goal in treating noncervical human papillomavirus infection is the elimination of lesions; eradication of the virus is not yet possible. Current forms of treatment include cryotherapy, podophyllum resin, podophilox, trichloroacetic acid, laser ablation, loop electrosurgical excision procedure (LEEP), fluorouracil and alpha interferon. Success in treating condyloma may be increased if the area is first soaked with 5 percent acetic acid to more clearly show the extent of the local infection. Recurrence is a problem no matter what form of therapy is used.

Condylomata Acuminata↗

PubMed1990

[17 Beta-estradiol interaction with haptoglobin and its complex with hemoglobin].

The estradiol-binding capacity of sheep haptoglobin and its complex with hemoglobin was investigated. It was shown that in the presence of H2O2 the haptoglobin-hemoglobin complex tightly binds 17 beta-estradiol. No dissociation of the estradiol-protein complex occurs after its precipitation with trichloroacetic acid and steroid extraction with the ester. It is supposed that the 17 beta-estradiol is bound to the protein by covalent bonds; this binding is characteristic only of the haptoglobin-hemoglobin complex but not of haptoglobin alone.

Animals↗

PubMed1980

The extraction of inositol-containing phospholipids and phosphatidylcholine from Saccharomyces cerevisiae and Neurospora crassa.

By use of fungi grown in the presence of [3H]-inositol and [14C]choline, we have explored methods for the quantitative extraction of inositol-containing phospholipids and phosphatidylcholine. Slightly alkaline mixtures of both ethanol-water and ethanol-diethylether-water at elevated temperatures were shown to effectively extract these lipids from intact Saccharomyces cerevisiae and Neurospora crassa. Some previously published procedures fail to completely extract to very polar phosphoinositol-containing sphingolipids of these organisms. Trichloroacetic acid can be used with caution in killing cells prior to extraction; lipid destruction can occur at elevated concentrations and temperatures. Complete extraction of these very polar lipids with polar solvents also results in an extract containing significant amounts of non-lipids.

Inositol↗

PubMed1977

Fractionation studies on the absorption of labelled immunoglobulin G by the gut of young rats.

1. Centrifugation in density gradients was used to study the fragments produced during intraluminal and intracellular digestion, after the injection of 125I-labelled immunoglobulin G (IgG) into different regions of the small intestine of 14 to 15-day-old (pre-closure) and 24-day-old (post-closure/ rats. 2. After injection into the proximal small intestine and into the ileum of pre-closure animals, the bulk of the radioactivity recorded for gut washes and gut homogenates was located at 4S-7S. The serum from animals which had received injections into the proximal small intestine had high radioactivity and one peak at 7S; the serum from animals which had received injections into the ileum had low radioactivity and no activity in the 7S region. 3. After injection into the proximal small intestine of post-closure animals, the bulk of the radioactivity recorded for gut wash samples was located at 3-5S--5S. Gut homogenates had peak activity at 2-5S--4S. Thus large molecular weight products can be absorbed by the proximal enterocytes of post-closure rats and degraded. The sera of these animals had low radioactivity. 4. After injection into the distal small intestine of post-closure animals, the bulk of the radioactivity recorded for gut wash and gut homogenate samples was located at 4S-7S and in this respect the radioactivity plots resembled those for (2) above. Serum radioactivity was low. 5. The effect of precipitation with trichloroacetic acid and incubation with specific antiserum upon the radioactivity of gut washes, gut homogenates and serum samples was recorded. 6. The relevance of these findings to studies on the transmission of protein by the rat small intestine is discussed.

Animals↗

PubMed1988

Measurement of microgram quantities of protein by a generally applicable turbidimetric procedure.

A modified turbidimetric method for protein determination which involves the use of trichloroacetic acid as the precipitating agent is described. Maximal turbidity develops in less than 30 min and is stable for at least 120 min. A linear relationship between turbidity at 340 nm and protein concentration is observed between 2 and 40 micrograms protein. Sodium dodecyl sulfate is added to avoid the interference by nonionic and cationic detergents and lipids and to decrease the protein-to-protein variation. The use of cetyltrimethyl ammonium bromide provides a two-step procedure to correct for the contribution of contaminating nucleic acid. Many compounds which interfere with other protein quantitation methods have no effect on this system. The interference of commonly used reagents as sucrose and urea can be easily corrected. This procedure compared favorably with the most widely used protein quantitation methods in simplicity, sensitivity, and specificity.

Cetrimonium↗

PubMedDate not supplied

Assembly of electroactive layer-by-layer films of hemoglobin and polycationic poly(diallyldimethylammonium).

Layer-by-layer (PDDA/Hb)(n) films were assembled by alternate adsorption of positively charged poly(diallyldimethylammonium) (PDDA) and negatively charged hemoglobin (Hb) at pH 9.2 from their aqueous solutions on pyrolytic graphite electrodes and other substrates. The assembly process was monitored and confirmed by quartz crystal microbalance (QCM), UV-vis spectroscopy, and cyclic voltammetry (CV). CVs of (PDDA/Hb)(n) films showed a pair of well-defined, nearly reversible peaks at about -0.34 V vs SCE at pH 7.0, characteristic of Hb heme Fe(III)/Fe(II) redox couple. Positions of Soret absorption band and infrared amide II band of Hb in (PDDA/Hb)(8) films suggest that Hb in the films keeps its secondary structure similar to its native state. The electrochemical parameters of (PDDA/Hb)(8) films were estimated by square wave voltammetry, and the thickness of the PDDA/Hb bilayer was estimated by QCM and scanning electron microscopy. Trichloroacetic acid and nitrite (NO(2)(-)) were catalytically reduced at (PDDA/Hb)(8) film electrodes. The electrochemical catalytic reactions of O(2) and H(2)O(2) on (PDDA/Hb)(8) films were also studied.

Catalysis↗

PubMed1984

Estimation of hydrogen peroxide in plant extracts using titanium(IV).

Methods for the estimation of hydrogen peroxide in acetone extracts using titanium(IV) are likely to overestimate hydrogen peroxide when applied to plant leaves. Pigments appear to co-precipitate with the titanium complex and cannot be removed by washing with solvents. Fluoride, which specifically removes the color of the titanium-peroxide complex, removes only some of the color from the reactions with plant extracts. This problem has been avoided by extracting tissues with trichloroacetic acid, and measuring peroxide against catalase-treated blanks by its reaction with the complex of titanium(IV) with 4-(2-pyridylazo) resorcinol. Levels of hydrogen peroxide in leaves of a variety of species were found to range from about 0.1 to 0.6 mumol X g-1.

Catalase↗

PubMed1985

Metabolites of chlorinated solvents in blood and urine of subjects exposed at environmental level.

After a two-level selection, 141 blood donors living in Milan, Italy, were analyzed for their content of plasma and urinary trichloroacetic acid (TCA) and trichloroethanol (TCE). Environmental levels of exposure to trichloroethylene (TRI) and tetrachloroethylene (PER) through drinking water and air were also measured. The plasma TCA levels were in the range of previously found concentrations. Relationships among plasma and urinary metabolites were found and discussed.

Adolescent↗