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PubMed1984

Novel metabolites of trichloroethylene through dechlorination reactions in rats, mice and humans.

The excretion and biotransformation of [14C]trichloroethylene (Tri) has been studied in female rats and mice. Seventy-two hours after a single oral dose of 200 mg/kg, rats exhaled 52% and mice 11% of the recovered radioactivity as unchanged Tri, and 1.9% and 6%, respectively, as 14CO2. Rats excreted 41.2% of the recovered radioactivity in the urine, in contrast to mice where urinary activity amounted to 76%. The isolation of urinary metabolites was accomplished by reversed-phase HPLC, using a water-methanol gradient. After chemical derivatization, a combination of radio-GC and GC/MS was used for identification. The metabolites identified in rat urine were: trichloroacetic acid (15.3%); trichloroethanol, free (11.7%) and as the glucuronide (61.9%); dichloroacetic acid (2.0%); oxalic acid (1.3%) and N-(hydroxyacetyl)-aminoethanol (HAAE) (7.2%). In mice, trichloroethanol (free and in several conjugated forms) is the main metabolite of Tri (94.3%), but small amounts of HAAE (4.1%) and oxalic acid (0.7%) are also excreted. Only traces of dichloro- and trichloroacetic acids were found in this species. In human male subjects, HAAE was also identified as a urinary metabolite of Tri after exposure of two volunteers to 200 ppm Tri for 6 hr. The identification of HAAE and oxalic acid as metabolites indicates hydrolytic dechlorination reactions in the metabolism of Tri.

Administration, Oral↗

PubMed1966

Xylem sap flow as affected by metabolic inhibitors and girdling.

The flow of sap in Populus tremuloides was studied by the thermoelectric method immediately prior to and at several periods of time after radical girdling. Similarly, the flow of sap in Betula papyrifera was studied before and after girdling or injection with metabolic inhibitors or a filtrate of a culture of Ceratocystis ulmi.None of the treatments caused any significant change in the speed at which the sap flowed. However, the rate at which the temperature rose at the upper (downstream) thermocouple decreased significantly in girdled trees and in most trees treated with metabolic inhibitors. That decrease was first noticed 4 days after poisoning with 0.1 m mercuric chloride, and 1 day after poisoning with either 0.01 m picric acid or a culture filtrate of Ceratocystis ulmi. A 0.05 m trichloroacetic acid solution caused a decrease in the rate of temperature rise about 2 hours after the tree was injected. The rate of temperature rise returned to normal the next day after the injection with trichloroacetic but again showed a decrease after 42 days.Increases in the rate of heat rise were noted the day after the birch trees were girdled, and all girdled trees showed a significant decrease in the rate of heat rise sometime after they were girdled. Many of the girdled trees showed no sap flow or even an apparent downward flow of xylem sap sometime after girdling.Laboratory experiments indicated that the blocking of the vessels by air emboli would result in a significant change in the rate of temperature rise, not accompanied by a significant change in the speed at which the sap flowed. Since air emboli caused similar results to those actually experienced in the field, the data are interpreted as the result of blocked or nonfunctional vessels.All of the data agree with that of earlier workers. Cessation of upward flow occurs only in girdled trees after rather long periods of time. It is suggested that cessation could be caused by tyloses and air emboli. All of the data are also in agreement with the passive theories of sap ascent. However, the trichloroacetic acid experiments suggest the existence of a repair mechanism or a second means of sap movement.

Journal Article↗

PubMedDate not supplied

The Blue Peel: how to do it less expensively and faster.

One well accepted and popular method worldwide for trichloroacetic acid peels is the Obagi Blue Peel technique (Obagi Medical Products, Long Beach, CA). The peel solution is prepared by mixing a fixed volume of 30% trichloroacetic acid with the commercially available Blue Peel base. The authors suggest modifications for performing the peeling faster and less expensively: 1) preparing a larger volume of peel solution from each tube of Blue Peel base; 2) using higher concentrations of peel solution to reduce the number of coats necessary for reaching the desired depth of peel; and 3) storing the solution, as there is no need to adhere to the manufacturer's instructions to prepare the solution immediately before conducting the peel procedure to ensure homogeneity of the solution. The prepared solution can be stored at least 1 year.

Caustics↗

PubMed1989

Genetic toxicology of 1,1,2-trichloroethylene.

1,1,2-Trichloroethylene (TCE) is a widely used halogenated solvent, produced in hundreds of millions of kg each year for industrial purposes. Occupational and environmental exposure of human populations to TCE has been reported in industrialized areas. Long-term carcinogenicity studies in rodents demonstrate that exposure to high doses of TCE results in the induction of liver and lung tumors in the mouse, and tumors of the kidney and the testis in the rat. An indirect mechanism, based on the stimulation of liver peroxisome proliferation by TCE metabolites, was proposed to explain species differences in TCE hepatocarcinogenicity. Mutagenicity studies indicate that TCE is weakly active both in vitro, where liver microsomes produce electrophilic TCE metabolites, and also in vivo in mouse bone marrow, where high rates of micronuclei, but no structural chromosome aberrations, are found. Among TCE metabolites, trichloroacetic acid was reported to be carcinogenic to mouse liver. Furthermore, both trichloroacetic acid and chloral hydrate were found to be genotoxic in vivo, inducing structural and numerical chromosome abnormalities, respectively.

Animals↗

PubMed1976

Failure of endotoxin to increase nonspecific resistance to infection of lipopolysaccharide low-responder mice.

In vitro and in vivo responses to lipopolysaccharide (LPS) and various other bacterial immunostimulants were compared in c3H/He low-responder mice. The principal findings were as follows. (i) Their splenic lymphocytes were stimulated by various gram-negative mitogens such as an Escherichia coli peptidoglycan, a detoxified derivative of LPS, and even endotoxins extracted by trichloroacetic acid that are known to contain protein; spleen cells of these mice were also transformed by two other B-cell mitogens extracted from acid-fast organisms. (ii) Their macrophages were refractory to LPS and weakly responsive to a mycobacterial prepartion. (iii) LPS failed to elicit nonspecific resistance in these mice against Klebsiella pneumoniae infection. (iv) Endotoxin extracted by trichloroacetic acid and a mycobacterial preparation that could increase nonspecific resistance to infection in other strains did not protect C3H/He mice against a challenge by K. pneumoniae, although both prepartions could evoke nonspecific responses of B cells in this low-responder subline.

Animals↗

PubMed1982

Method for determining serum pepsinogen concentration, using pepsin standards and ultraviolet absorbance.

A simplification of the traditional hemoglobin methods for determining serum pepsinogen concentration was developed. In this method, 10% trichloroacetic acid solution was added to control samples, and hemoglobin substrate was added to controls and active enzyme samples; standards and samples were incubated for 18 hours, the proteins in the active tubes were precipitated with trichloroacetic acid and removed by filtration, and the absorbances of the supernatant of each standard and sample at 280 nm were measured. The major differences between this method and other methods for determining pepsinogen values are that the preacidification of serum with hydrochloric acid was eliminated, the incubation period was reduced to 18 hours (down from 24 hours), the relative pepsinogen concentration was determined by measuring the concentration of hydrolysis products, using ultraviolet, rather than visible absorbance, and a pepsin standard curve was used to determine the serum pepsinogen concentration. Comparison of freshly prepared pepsinogen and pepsin standard curves indicated that the pepsinogen preparations were slightly more active than the pepsin preparations (on a weight-to-weight basis) on the same substrate. Pepsin standards are used because they are more stable than pepsinogen standards. Three linear standard curve ranges were used: O 10 to 100, 50 to 300, and 100 to 500 ng of pepsinogen/ml of serum. The use of pepsin standard curves permits some variability of the incubation conditions without altering the results. For best results, the hemoglobin substrate solution should be prepared daily. This method may be useful in diagnosing ostertagiasis.

Animals↗

PubMed2000

A new diquat derivative appropriate for colourimetric measurements of biological materials in the presence of paraquat.

A new colourimetric method is described for the quantification of diquat using a yellow-coloured derivative produced by heating diquat in alkaline solution at 80 degrees C. The absorption maximum of the yellow derivative is 420 nm and the molar absorption coefficient is 2.76 x 10(4) (0.15 in 1 microgram diquat/ml with 1 cm light path). The absorption at 420 nm shows a linear concentration dependence in the range 0.1-10 micrograms/ml and fading of the colour is about 5% after 1 h. Under the same conditions, paraquat does not produce any coloured products. The concentration of diquat in the solution containing both diquat and paraquat can be determined by the absorption of diquat derivative at 420 nm without interference from paraquat. By adding sodium dithionite to the solution the concentration of paraquat can be determined by the absorption of paraquat radicals at 600 nm without interference from diquat, because the yellow derivative does not react with dithionite. This yellow diquat derivative can be extracted completely with cyclohexanol by saturating the solution with Na2SO4. The absorption maximum in cyclohexanol shifts to 440 nm with the same molar absorbance and the same half-band width as in water. Fading of the colour is less than 5% after 24 h in cyclohexanol. Perchloric acid (3%) and trichloroacetic acid (4.5%) which are often used for deproteinization of tissue homogenates, do not inhibit production of the coloured derivative at pH 13.5 or extraction of the derivative with cyclohexanol. This method is suitable for a quick determination of small amounts of diquat in tissues, since the extraction with cyclohexanol not only concentrates the derivative rapidly but also quite efficiently eliminates the coloured substances in tissue homogenates. The detection limit of diquat is 0.02 microgram/ml for blood and 0.05 microgram/g for liver when 1 ml or 1 g is used for analysis. In three human cases of fatal intoxication, both paraquat and diquat were quantified using 50 microliters of serum. In non-toxic dosing of diquat to rats for 14 days, the diquat level was highest in the spleen followed by the kidneys.

Animals↗

PubMed1984

Sources of error in estimating radioactivity in protein from cell cultures by liquid scintillation counting.

In this study, several common sample preparation techniques for liquid scintillation counting were critically reviewed. It has been shown that techniques such as NaOH or formic acid solubilization of trichloroacetic acid (TCA)-precipitated proteins led to underestimation of the radioactivity by 20-40%; this loss was not corrected by either internal or external standardization. Hydrolysis of the proteins with 6 N HCl or Pronase significantly increased the recovery of the labeled proteins. Also, 10% of the labeled cell proteins remained on the dish when cells were scraped into buffer; these labelled proteins could be recovered either by in situ hydrolysis with Pronase or by solubilization and scraping in 0.3 N NaOH. These techniques increased the recovered radioactivity by 50-60%, allowing quantitative measurements to be made over a 3-day chase period. A possible mechanism and the implications of this observation were discussed.

Animals↗

PubMed1987

The mitogenic effects of vasoactive neuropeptides on cultured smooth muscle cell lines.

In order to investigate the relationship between the biochemical pathways that characterize contraction and cell growth, we have studied both contraction, mitogenesis and protein synthesis induced by the vasoactive neuropeptides, substance P (SP), calcitonin gene related peptide (CGRP) and vasoactive intestinal polypeptide (VIP) on four different established vascular and nonvascular smooth muscle cell lines. Contraction in vitro was evaluated by light microscopy and recorded photographically. Mitogenesis and protein synthesis were evaluated by [3H]-thymidine incorporation into cells and [3H]-amino acid incorporation into trichloroacetic acid precipitated materials, respectively. SP stimulated mitogenesis of A7r5 cells (embryonic rat aorta), but failed to induce significant contraction of these cells, whereas, SP induced contraction of cultured adult rat vascular smooth muscle cells (VSMC), but failed to stimulate mitogenesis. CGRP and VIP stimulated mitogenesis and protein synthesis, respectively, of DDT1MF-2 cells (hamster vas deferens), but neither induced contraction of this cell line. All three neuropeptides showed no effect on BC3H1 (mouse smooth muscle-like) cells. These results suggest that neuropeptides with vasoactive properties modulate different stages of cellular mitogenic responses which may be regulated by the degree of maturation of smooth muscle cell.

Animals↗

PubMed1985

Presence of di- and polyamines covalently bound to protein in rat liver.

Acid hydrolysis of trichloroacetic acid precipitate from rat tissue (liver, kidney and testis) homogenate released significant amounts of acid-insoluble putrescine, spermidine and spermine. Following incubation of liver homogenate with [1,4-14C]putrescine, 1.4% of total radioactivity and 1.0% of labelled diamine were recovered in the acid-insoluble fraction. Exhaustive digestion of acid-precipitable material with proteinases (Pronase, aminopeptidase M, carboxypeptidase A, B and Y) revealed the presence of di- and polyamines and of N1-(gamma-glutamyl)spermidine, N1-(gamma-glutamyl)spermine and N1,N12-bis(gamma-glutamyl)spermine. These derivatives were identified both by chromatographic analysis and by enzymatic digestion with purified gamma-glutamylamine cyclotransferase. The finding of di- and polyamine gamma-glutamyl derivatives in the proteinase-digested acid-insoluble fraction of homogenate may be considered as a proof of the in vivo transglutaminase-catalyzed binding of polyamines to proteins. This evidence suggests that di- and polyamines might have an important role in mammalian tissues through covalent binding to proteins by either one or both the primary amino groups.

Animals↗

PubMed2004

Biodegradation of haloacetic acids by bacterial enrichment cultures.

Haloacetic acids (HAAs) are toxic organic chemicals that are frequently detected in surface waters and in drinking water distribution systems. The aerobic biodegradation of HAAs was investigated in serum bottles containing a single HAA and inoculated with washed microorganisms obtained from enrichment cultures maintained on either monochloroacetic acid (MCAA) or trichloroacetic acid (TCAA) as the sole carbon and energy source. Biodegradation was observed for each of the HAAs tested at concentrations similar to those found in surface waters and in drinking water distribution systems. The MCAA culture was able to degrade both MCAA and monobromoacetic acid (MBAA) with pseudo-first order rate constants of 1.06 x 10(-2) and 1.13 x 10(-2) l(mg protein)(-1) d(-1), respectively, for concentrations ranging from 10(-5) to 2 mM. The pseudo-first order rate constant for TCAA degradation by the TCAA culture was 6.52 x 10(-3) l(mg protein)(-1) d(-1) for concentrations ranging from 5.33 x 10(-5) to 0.72 mM. The TCAA culture was also able to degrade MCAA with the rate accelerating as incubation time increased. Experiments with radiolabeled HAAs indicated that the 14C was primarily converted to 14CO2 with minor incorporation into cell biomass. The community structure of the enrichment cultures was analyzed by both cultivation-dependent and cultivation-independent approaches. Denaturing gradient gel electrophoresis (DGGE) of the PCR-amplified 16S rRNA gene fragments showed that each of the two enrichment cultures had multiple bacterial populations, none of which corresponded to HAA-degrading bacteria cultivated on HAA-supplemented agar plates. This research indicates that biodegradation is a potential loss mechanism for HAAs in surface waters and in drinking water distribution systems.

Acetates↗

PubMed2004

Protein precipitation for the analysis of a drug cocktail in plasma by LC-ESI-MS.

Three protein precipitation (PP) procedures with acetonitrile (ACN), perchloric acid (PA) and trichloroacetic acid (TCA) were investigated for the analysis of a drug cocktail from human plasma samples containing three pharmaceutical compounds and their primary metabolites. For this purpose, a capillary liquid chromatography-electrospray ionisation-mass spectrometry (LC-ESI-MS) method was developed for the simultaneous analysis of the six tested compounds in less than 6 min. Matrix effect was tested for each PP procedure by means of a post-column infusion system. The three PP techniques were found effective in removing proteins from human plasma and were fully compatible with capillary LC-ESI-MS analysis. However, with acid precipitations, low analyte recovery and a high variability, probably due to analyte coprecipitation, were obtained. Finally, ACN was found to be the most effective PP technique with a recovery higher than 80% and CV inferior to 6%.

Blood Proteins↗

PubMed2001

Fast, simple and cost-effective determination of thiopental in human plasma by a new HPLC technique.

BACKGROUND: Thiopental is an anaesthetic drug that is largely used in both short-term and long-term infusion. After long-term infusion of thiopental, non-linear and inter-individual-dependent pharmacokinetics occur because of the saturation and/or induction of the metabolism. Clinical monitoring is important so that therapeutic adjustments can be made in many of the different pharmacological treatments, especially when long-term infusion is required. We describe a new, rapid HPLC method for the determination of plasma thiopental. METHODS: Sample preparation involved precipitation of plasma proteins using a mixture of methanol, zinc sulfate and ethylene glycol, and containing the internal standard 5-ethyl-5-p-tolyl-barbituric acid. After adding trichloroacetic acid, the sample was centrifuged and the supernatant was injected into a C(18) reversed-phase column. The mobile phase used was water-methanol-acetonitrile (50:40:10, v/v). The eluent was monitored at 290 nm. RESULTS: The calibration curve was linear from 0.2 to 100 microg/mL. Precision, calculated as the coefficient of variation (%), was in the range of 3.62-0.70% for the within-day assay and 5.77-1.51% for the between-day assay. The absolute recoveries obtained from supplemented samples were never less than 100%. CONCLUSIONS: This technique shows good reliability and seems to be suitable for a very fast and simple therapeutic monitoring of plasma thiopental.

Anesthetics, Intravenous↗

PubMed1984

Determination of the herbicides paraquat and diquat in blood and urine by gas chromatography.

A gas chromatographic method is described for determining paraquat (I) and diquat (II) in human blood and urine. I or II was readily precipitated as its reineckate complex (III and IV) by addition of Reinecke reagent, although blood required deproteination with 3.4% perchloric acid or 10% trichloroacetic acid. The precipitation is completed in 1 h at room temperature. III and IV were easily reduced by treatment with a mixture of sodium borohydride and nickel(II) chloride to afford corresponding perhydrogenated products, 1,1'-dimethyl-4,4'-bipiperidine (V) from III and trans- and cis-perhydrodipyrido[1,2-a:2',1'-c] pyrazine (VI) from IV. The perhydrogenated products were determined by gas-liquid chromatography (GLC) without interference from the original components of the blood and urine. The GLC method (5% potassium hydroxide solution with 5% Apiezon L on Chromosorb W AW DMCS) is suitable for simultaneous determination with hydrogen flame-ionization detection in the range 1-70 micrograms/ml (0.7-50.7 micrograms/ml as I ion; 0.5-35.6 micrograms/ml as II ion) of I and II in blood and urine. The method could be applicable to the determination of the chemicals in postmortem tissue and as pollutants in soils.

Chemical Phenomena↗

PubMed1997

Non-heme (Fe3+) in the lung increases with age in both humans and rats.

Increasing non-heme iron concentrations in host tissues are potentially significant, because they can be associated with an increased risk of injury including infections, fibrosis, and neoplasms. We tested the hypothesis that non-heme (Fe3+) in the lung increases with age in both humans and rats. Human tissue was collected at autopsy before fixation occurred. The total number of specimens was 131 with 78 nonsmokers and 53 smokers. Tissue was hydrolyzed in 3 N hydrochloric acid and 10% trichloroacetic acid. Supernatant (Fe3+) was measured with a thiocyanate assay. Non-heme (Fe3+) increased with age in nonsmokers. The correlation coefficient between lung (Fe3+) and age in the nonsmokers was 0.58 (p < 0.0001). Iron stains were negative, whereas those for ferritin demonstrated increased uptake with aging. Smokers had significantly greater non-heme (Fe3+) relative to nonsmokers (101.1 and 46.0 micromol/L respectively; T = 11.44, p < 0.0001). Lung non-heme (Fe3+) in smokers also increased with age (r = 0.75; p < 0.0001). Iron stains demonstrated uptake in the proximity of retained pigmented material. Ferritin stains demonstrated intense uptake in both the macrophages and the airway and alveolar epithelium of smokers. An animal model was also analyzed for an effect of aging on lung non-heme (Fe3+). At specified times between 30 and 186 days of age, rats (n = 48) were anesthetized and exsanguinated, and the lungs were excised. In rats, similar to humans, a positive correlation was seen between lung non-heme (Fe3+) and age (r = 0.73; p = 0.007). Stains for iron in rat lung were uniformly negative, whereas those for ferritin demonstrated increased uptake by airway and alveolar epithelium in older rats. We conclude that non-heme (Fe3+) in lung tissue increases with age in both humans and rats. Elevations in lung non-heme (Fe3+) could contribute to an increased incidence of pneumonias, pulmonary fibrosis, and bronchogenic carcinoma observed among older individuals.

Adolescent↗

PubMed2003

Aspartate-induced aminoacylase folding and forming of molten globule.

Aspartate is an osmolyte found in some marine invertebrates and cyclostome fish. The aspartate-induced unfolding of N-acylamino acid amido hydrolase (aminoacylase) has been studied by measuring enzyme activity, fluorescence emission spectra, 8-anilino-1-naphthalenesulfonate (ANS) fluorescence spectra and far-UV circular dichroism (CD) spectra. The results showed that aspartate caused the inactivation and unfolding of aminoacylase. Surprisingly, increasing concentration of aspartate showed the "acid-induced folding", which used to be seen only in strong acids or salts at much lower pH. Although aspartate has the pI of 2.77 that is the lowest among all the free amino acids, it is actually a weak acid. It is thus of great interest why it causes this phenomenon to happen. The relative change of intrinsic fluorescence and ANS binding spectra have shown that there existed a stable molten globule state of aminoacylase with slightly disrupted tertiary structure and more hydrophobic surface. The molten globule state indicates that intermediates existed during aminoacylase refolding process. Unlike the other acids, such as trichloroacetic acid, there is no precipitation observed as the aspartate concentrations increased. It suggests the aspartate anions have an osmotic effect for the molten globule formed during unfolding process. Binding of aspartate anion to the protonated protein, which minimizes the intramolecular repulsion, might explain the osmotic effect of this amino acid in the nature. The results also showed the Apo-aminoacylase followed similar rules as Holo-enzyme, which suggested the zinc ion may play more important roles on activity other than structure.

Amidohydrolases↗

PubMed1974

Histone F1 of Tetrahymena macronuclei: unique electrophoretic properties and phosphorylation of F1 in an amitotic nucleus.

Histone fraction F1 has been isolated and purified from macronuclei of the ciliated protozoan, Tetrahymena pyriformis. In many respects, Tetrahymena F1 is similar to that of other organisms. It is the only Tetrahymena histone soluble in 5% perchloric acid or 5% trichloroacetic acid, has a higher molecular weight than any other Tetrahymena histone, is the histone most easily dissociated from Tetrahymena chromatin, and is susceptible to specific proteolytic cleavage. However, unlike F1 in all other organisms, Tetrahymena F1 is not the slowest-migrating histone fraction when analyzed by polyacrylamide gel electrophoresis at low pH. Tetrahymena F1 also exhibits unusual behavior in sodium dodecyl sulfate-containing polyacrylamide gels, migrating faster than calf thymus F1 at pH 10, and slower than calf thymus F1 at pH 7.6. Tetrahymena F1 was found to be highly phosphorylated in rapidly growing cells, suggesting that the relationship between cell replication and F1 phosphorylation previously observed in mammalian cells may extend to all eukaryotes. The observation that extensive F1 phosphorylation occurs in macronuclei, which divide amitotically, argues against a unique role for F1 phosphorylation in the process of chromosome condensation at mitosis.

Amino Acids↗

PubMed1996

Kinetic studies on depurination and detritylation of CPG-bound intermediates during oligonucleotide synthesis.

Fully protected CPG-immobilized monomer, dimer and trimer oligonucleotides were used to study depurination during the chemical synthesis of oligonucleotides. Disappearance of the oligonucleotide during acid exposure time relative to an internal thymidine standard not subject to depurination was monitored by reverse phase HPLC analysis. Depurination half-times obtained for dichloroacetic acid (DCA) and trichloroacetic acid (TCA) in methylene chloride were found to be 3% DCA >> 15% DCA > 3% TCA. In order to understand the implications of depurination during DNA synthesis, the detritylation kinetics of model compounds DMT-dG-pT dimer and DMT-[17mer] mixed-base sequence were also measured. These results improve our ability to properly balance the contradictory goals of obtaining maximum detritylation with minimum depurination in oligonucleotide synthesis.

Adenosine↗