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PubMed1989

[A screening method of analysis of middle weight molecules].

Using the screening method, the level of middle-mass molecules was examined in 192 donors and 44 patients with peritonitis. The following factors are essential for the reproducibility of the method and for decreasing the results scatter: (1) use of trichloroacetic acid for optic control and standardization of the preparation of this solution according to optic density; (2) photometry is carried out at a wavelength of 235-240 nm; (3) accurate collection, preparation, and storage of the material; (4) calculation of the indexes of distribution according to 238/260 and 238/280 ratios. Adherence to these recommendations and to some others essentially improves the clinical diagnostic potentialities of the described method for the evaluation of peritonitis severity and of the body intoxication.

Humans↗

PubMed2001

The application of physiologically based pharmacokinetic modelling in the analysis of occupational exposure to perchloroethylene.

A physiologically based pharmacokinetic model for perchloroethylene was parameterized, calibrated and validated using anatomic, physiologic, biochemical and physicochemical data obtained from the literature. The model was used to analyse human exposure data obtained under controlled conditions and from dry cleaning establishments in the Padua area of northern Italy. Whilst the model satisfactorily simulated the urinary excretion of trichloroacetic acid, following experimental inhalation exposure to 10, 20 and 40 ppm perchloroethylene under controlled conditions the opposite was true for the occupational exposure data. However, further model refinement to incorporate inter-individual variability of anatomical, physiological and biochemical parameters which have an impact on model output, would further improve the predictive capabilities of the model. The possibility of perchloroethylene and trichloroethylene co-exposure in the occupational setting was indicated by the model.

Calibration↗

PubMed1990

Column liquid chromatography of endotoxins.

A new, fast and highly reproducible column liquid chromatographic method was elaborated for the analysis and small-scale preparative isolation of endotoxin from Serratia marcescens Bizio (ATCC No. 264). This procedure detects contaminants of such preparations with high sensitivity and it is capable of separating them from endotoxic components. Extensive heterogeneity of both 5% trichloroacetic acid and phenol-water-extracted endotoxin preparations was recorded. Heterogeneity among the endotoxic components of purified preparations could also be detected by this method. Measurements of biological activities, such as Limulus amoebocyte lysate activation, lymphoblastogenesis (mitogenicity) and tumor necrosis factor (TNF) liberation were carried out on the chromatographically separated fractions. During these studies, non-toxic but in vitro TNF-generating components of crude endotoxin extracts were also detected.

Animals↗

PubMed1983

In vivo fate of 125I SS-B (La) injected into mice.

The fate of the radiolabelled soluble cellular antigen SS-B (La) was compared with that of other 125I-labelled proteins of known molecular weight (MW) and electrostatic charge, following i.v. injection into BALB/c mice. The plasma half-life of 125I-SS-B was 3 min, while that of 125I-bovine serum albumin (similar MW and electrostatic charge) was 270 min. 125I-heat-aggregated IgG (MW greater than 1 x 10(6)) and 125I-7S human IgG (MW 168,000) had plasma half-lives of 40 min and greater than 300 min, respectively. Liver and kidney showed preferential uptake of 125I-SS-B, followed by a rapid decrease in radioactivity. During this time low MW, trichloroacetic acid (TCA) soluble, material appeared in urine. This suggests a specific uptake mechanism followed by a catabolic phase. These studies demonstrate that normal mice remove 125I-SS-B rapidly from the circulation and then degrade it. This rapid antigen elimination may protect against the induction of potentially harmful autoantibody responses.

Animals↗

PubMed2000

Corneal opacity, hydration and endothelial morphology in the bovine cornea opacity and permeability assay using reduced treatment times.

The purpose of this study was to determine whether the standard bovine cornea opacity and permeability (BCOP) assay exposure time of 10 minutes overestimates the ocular irritancy of chemical substances. Corneas were subjected to BCOP protocol following 30-second and 1-minute exposures to irritants. Corneal opacity and hydration (mg H(2)O/mg cornea) were then measured and compared to data obtained after 10 minute irritant treatments. For most test substances corneal opacity and hydration were lower following reduced exposure times. It is suggested that using shorter exposure times in BCOP protocol may be more predictive of human response to ocular irritants, since irritants are usually in brief contact with the ocular surface during accidental exposure. A second purpose of this study was to examine effects of irritants on the corneal endothelium. Corneas were treated according to BCOP protocol following exposure to irritants for 1 or 10 minutes. The endothelium was stained with Alizarin Red and trypan blue, and examined using light microscopy. Severe irritants, such as NaOH and trichloroacetic acid, cause endothelial cell death. It was also determined that simply mounting the cornea in the BCOP assay holders caused damage to 20% of the endothelial cells. Because the endothelium is essential for normal corneal transparency and hydration, it is suggested that examination of the endothelium be added to the BCOP assay and that optimization of the assay will require modification of the cornea holders.

Animals↗

PubMed1988

An alternative method for assaying cerebrospinal fluid protein in the presence of methotrexate.

Therapeutic concentrations of methotrexate can cause significant positive interference in cerebrospinal fluid (CSF) protein values when assayed in the Du Pont aca. Conversely, our modified turbidimetric method, in which trichloroacetic acid (TCA) plus a sample blank containing dilute hydrochloric acid is used in place of TCA, exhibits little or no interference from methotrexate. This was verified by assaying solutions that contained a constant amount of protein (approximately 430 mg/L) and various amounts of methotrexate (0.0-2.3 x 10(-4) mol/L) by both the Du Pont aca and the manual turbidimetric method. As expected, the aca results showed increasing protein values with increasing methotrexate, whereas the manual method gave results approximating the expected protein value irrespective of the methotrexate concentration.

Cerebrospinal Fluid Proteins↗

PubMed1972

A possible ribosomal-directed regulatory system in Euglena gracilis. Chlorophyll synthesis.

Cycloheximide at concentrations of 0.1-100mum stimulated chlorophyll synthesis when dark-grown cells of Euglena were illuminated. Chloramphenicol (1-4mm) inhibited chlorophyll synthesis. The effect of cycloheximide on the incorporation of [(14)C]leucine into material insoluble in trichloroacetic acid, and its failure to affect the incorporation of [(32)P]orthophosphate into such material in short incubations, are interpreted as evidence that cycloheximide specifically inhibits protein synthesis by 80S ribosomes. Since the inhibitory effect of chloramphenicol on chlorophyll synthesis is counteracted by the presence of cycloheximide, it is suggested that chlorophyll synthesis is subject to control by a cytoplasmic repressor synthesized on 80S ribosomes, and to a de-repressor synthesized on 70S ribosomes.

Carbon Isotopes↗

PubMed1986

Stability of acetaldehyde fractions with various hemoglobin fractions.

The stabilities of 14C-acetaldehyde with various hemoglobin fractions (HbA1a + b, HbA1a, and HbA0) were examined by determining amounts of adducts remaining after dialysis at 4 degrees C for various time intervals. Significant differences were found in the stabilities of adducts formed with various hemoglobin fractions. Acetaldehyde adducts formed with HbA1a + b were more stable to dialysis than adducts formed with HbA0 or HbA1c (7-8% of total adducts formed with HbA1a + b were stable to dialysis, compared with 4-5% stable adducts formed with either HbA0 or HbA1c). While only 37-57% of the trichloroacetic acid (TCA) precipitable adducts from HbA0 or HbA1c samples were stable to dialysis, 72-75% of TCA precipitable adducts from HbA1a + b were retained after dialysis. Posttranslational modification of hemoglobin by phosphorylated glycolytic intermediates appears to alter the physical properties of hemoglobin following further modification with acetaldehyde. In view of the increased amounts of glycosylated proteins found in patients with diabetes, these observations may be relevant to the pathogenesis of the sequelae of diabetes and/or alcoholism and the influence of one chronic illness on the other.

Acetaldehyde↗

PubMedDate not supplied

The chemical peel.

The spectrum of chemical peeling encompasses a diverse group of peeling agents with the ability to produce a wide range of cutaneous burns. The most spectacular peels are produced by the phenol formulas. The physician, however, is restricted in the number of potential candidates as determined by skin color and potential toxicity. While not as impressive, trichloroacetic acid peels are an excellent modality for treatment of actinic keratoses, actinic dermatitis and lentigoes. Improvement of rhytides, skin tone, and texture can be impressive. Utilization of TCA may require repetitive peeling to obtain the desired result. With the alarming increase in the incidence of severe facial solar radiation as manifested by multiple premalignant and in situ malignant lesions, therapeutic chemical peeling has become an increasingly important procedure. The dermatologic surgeon can not only eradicate the multitude of facial lesions present but also markedly diminish the incidence of new lesions.

Chemexfoliation↗

PubMed1978

Ultrastructural effects of chemical agents and moist heat on Bacillus subtilis. I--Effects on vegetative cells.

The ultrastructural alterations induced by treatment of vegetative Bacillus subtilis cells with organic solvents, trichloroacetic acid (TCA) and moist heat were examined by electron microscopy. Organic solvents disorganize the membrane and change the asymmetric unit membrane profile to a symmetric profile. They also lead to partial solubilization of the membrane and produce small or extensive gaps. Membrane damaging activity increases in the following order: xylene = toluene less than octanol less than choroform. TCA coagulates the cytoplasm which shows large, electron-dense, pronase-sensitive blocks. Moist heat alters both the membrane and the cytoplasm.

Bacillus subtilis↗

PubMed2003

Cationic liposomes enhanced firefly bioluminescent assay of bacterial ATP in the presence of an ATP extractant.

Cationic liposomes composed of two components, diethylaminoethyl-carbamoyl cholesterol and phosphatidylcholine, were applied to an enhancer for a firefly bioluminescent (BL) assay of bacterial ATP in the presence of an ATP extractant. Trichloroacetic acid (TCA), which inhibits the activity of luciferase, was used as an ATP extractant. Cationic liposomes enhanced the BL intensity as long as luciferase was active. The detection limits for cell numbers of Escherichia coli extracts in the presence of cationic liposomes and in water alone were 199 and 897 colony forming units ml(-1), respectively. The sensitivity for bacterial ATP in the presence of cationic liposomes was improved by a factor of 2.5 times compared to that in the presence of diethylaminoethyl-dextran.

Adenosine Triphosphate↗

PubMed2004

Myoglobin/sol-gel film modified electrode: direct electrochemistry and electrochemical catalysis.

Direct electrochemical and electrocatalytic behavior of myoglobin (Mb) immobilized on carbon paste electrode (CPE) by a silica sol-gel film derived from tetraethyl orthosilicate was investigated for the first time. Mb/sol-gel film modified electrodes show a pair of well-defined and nearly reversible cyclic voltammetric peaks for the Mb Fe(III)/Fe(II) redox couple at about -0.298 V (vs Ag/AgCl) in a pH 7.0 phosphate buffer solution. The formal potential of the Mb heme Fe(III)/Fe(II) couple shifted linearly with pH with a slope of 52.4 mV/pH, denoting that an electron transfer accompanies single-proton transportation. An FTIR and UV-vis spectroscopy study confirms that the secondary structure of Mb immobilized on an electrode by a sol-gel film still maintains the original arrangement. The immobilized Mb displays the features of a peroxidase and acts in an electrocatalytic manner in the reduction of oxygen, trichloroacetic acid (TCA), and nitrite. In comparison to other electrodes, the chemically modified electrodes used in this study for direct electrochemistry and electrocatalysis of Mb are easy to fabricate and fairly inexpensive. Consequently, the Mb/sol-gel film modified electrode provides a convenient way to perform electrochemical research on this kind of protein. It also has potential use in the fabrication of bioreactors and third-generation biosensors.

Animals↗

PubMed1980

A cohort study on workers exposed to trichloroethylene.

The mortality of 2,117 workers exposed to trichloroethylene sometime between 1963 and 1976 was studied. Their names were collected from the files of one biochemical laboratory performing urinary trichloroacetic acid determinations and from the Occupational Disease Register of Finland. Both the total mortality (SMR 69) and the cancer mortality (SMR 77) were lower than expected. Because of the young age structure and the brief follow-up time the results should be interpreted with caution. They suggest, however, that given as short a latency period as 6 to 13 years, trichloroethylene is not a strong human carcinogen. The present material provides a cohort with defined exposure for further follow-up.

Adolescent↗

PubMed1990

Bioanalysis of the peptide des-enkephalin-gamma-endorphin. On-line sample pretreatment using membrane dialysis and solid-phase isolation.

Des-enkephalin-gamma-endorphin is a neuroleptic endogenous peptide that is active in the central nervous system in extremely low concentrations. The pharmacokinetics of this peptide could not be studied in detail as a bioanalytical method for determining endogenous levels of this peptide in biological matrices was not available. Liquid chromatography with fluorescence reaction detection in principle offers sufficient sensitivity for this application, provided that a selective sample pretreatment can be performed. The development of a pretreatment method for plasma samples is described. After protein precipitation with trichloroacetic acid, high-molecular-weight compounds are removed using on-line continuous-flow dialysis. After dialysis, polar low-molecular-weight compounds, including those containing amino functions, are removed by solid-phase isolation, while simultaneously the analyte is concentrated. By means of valve switching the pretreatment system is coupled on-line to the liquid chromatographic system. With the developed system it is possible to determine desenkephalin-gamma-endorphin in plasma in the range 10-100 ng/ml.

Acetonitriles↗

PubMed1982

A comparative histologic study of the effects of three peeling agents and dermabrasion on normal and sundamaged skin.

This paper reports the histologic findings in normal and sundamaged skin, created by 60% trichloroacetic acid (TCA), 100% phenol, Baker's phenol mixture, and dermabrasion at 3 days and 60 days after treatment. Half of the peeled areas were unoccluded, and the other half were occluded. It was found that the various escharotic agents seem to wound sundamaged skin with the same type of graduation as non-sundamaged skin. Furthermore, a layer of enlarged papillary dermis consistently developed, the thickness of which seems directly related to the strength of the escharotic agent, or the overall wound depth or the healing time necessary for complete recovery.

Chemexfoliation↗

PubMed1995

Evaluation by SDS-PAGE and immunoblotting of residual antigenicity in hydrolysed protein formulas.

BACKGROUND: Extensively hydrolysed protein formulas are widely used as an alternative diet for children with cow's milk allergy. Partially hydrolysed protein formulas have been noted in some studies as useful in the prevention of allergy in infants at high risk of atopy. Although normally well tolerated, these 'hypoallergenic' products have been reported to cause serious immunological reactions in very sensitive subjects. OBJECTIVE: Starting from these considerations, we studied some commercial hydrolysed formulas in search of biological data supporting the observed clinical reactions. METHODS: We set up an electrophoretic method sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) which allowed us to study the molecular weight of peptides contained in hydrolysed products. Then, using the immunoblotting technique we evaluated the reactivity of circulating IgE (from serum of children allergic to cow's milk proteins) with the residual intact proteins and with the peptides present in these formulas. RESULTS: Both group of milk proteins (caseins and whey proteins) were important allergens for children included in this study. The presence of high-molecular polypeptides was shown in partial hydrolysed formulas as such and in extensive hydrolysed products after protein enrichment by trichloroacetic acid (TCA) precipitation. Intact residual proteins were mainly responsible for the formation of IgE-antigen complexes observed in immunoblotting. More rarely, polypeptides of partial hydrolysed formulas were involved in immunological responses. CONCLUSIONS: Both partial and extensive hydrolysed formulas could induce clinical reactions in very sensitive subjects. These responses are mainly associated with allergy to the small amounts of residual intact proteins.

Animals↗

PubMed1982

Overestimate of 125I-protein uptake from the adult mouse gut.

Gastric instillation of 125I-labelled protein in mice leads to rapid appearance of blood radioactivity which is precipitable with 10% trichloroacetic acid (TCA). The same occurs when Na125I is given by mouth. Parenteral administration of non-radioactive NaI before feeding Na125I or 125I-labelled protein inhibits the appearance of TCA-precipitable radioactivity in the blood. The results presented in this study show that measurement of TCA-precipitable radioactivity in the blood after feeding 125I-labeled protein is not a reliable method for studying the passage of macromolecules across the gastrointestinal barriers unless an excess of iodide is given.

Animals↗

PubMed2004

Plasma clearance and tissue distribution of radiolabeled leptin in the chicken.

Leptin is an adipose and liver tissue-derived secreted protein in chickens that has been implicated in the regulation of food intake and whole-body energy balance. In this study, the metabolic clearance and tissue uptake of leptin were examined in the chicken (Gallus gallus). Four-week-old broiler males were infused with (125)I-labeled mouse leptin. Chromatography of radiolabeled leptin in plasma produced two peaks, one at 16 kDa (free leptin) and a free iodine peak. No leptin binding protein in blood was detected. Leptin was cleared with a half-life estimate of 23 min. In order to investigate the tissue distribution and uptake of radiolabeled leptin, multiple tissues were removed from infused birds at 15 and 240 min post-infusion, and trichloroacetic acid (TCA)-precipitable radioactivity was determined. The amounts of radioactivity at 15 min post-infusion in the tissues in rank order were: kidney, testis, lung, spleen, heart, liver, small and large intestine, gizzard, pancreas, bursa, leg and breast muscle, adrenals, and brain. A slightly different pattern of distribution was observed at 240 min post-infusion. We conclude from these studies that unlike mammals, no circulating leptin binding protein is present in chickens. Leptin is metabolized and cleared very rapidly from blood by the kidney.

Animals↗