Trichloroacetic Acid Solution Research Articles

Chemical reconstruction of skin scars therapy using 100% trichloroacetic acid in the treatment of atrophic facial post varicella scars: A pilot study

Context:Chickenpox (varicella) is a common viral disease caused by Varicella zoster virus. Facial atrophic scars after varicella infection are not uncommon and pose a cosmetic problem. Like atrophic scars of other aetiologies, they are a difficult condition to treat. There are not enough references in the literature regarding efficient treatment of post varicella scars. High strength Trichloroacetic acid (TCA), which is known to cause dermal collagen remodelling, was used to treat varicella scars in the present study.Aims:The study was undertaken to assess the efficiency of Chemical Reconstruction of Skin Scars (CROSS) technique using 100% TCA in the treatment of atrophic facial post varicella scars. Settings and Design: Open label, pilot study.Materials and Methods:A total of 16 patients with atrophic facial post varicella scars were treated by focal application of 100% TCA solution by pressing down upon the scar surface by a toothpick (CROSS technique). Total 4 sittings were given at 2 weekly intervals and the results evaluated after 3 months of follow-up. Statistical analysis was carried out using Fischer's exact t-test.Results:All of the 13 patients who completed the study showed good clinical improvement, with 69% patients grading the response as excellent (>75%) improvement, whereas the rest 31% patients reporting good (51-75%) improvement. No significant complications were seen in any patient.Conclusions:CROSS technique using 100% TCA is a safe, cheap and effective therapy for the treatment of post varicella scars.

Quantitative determination of 2-mercaptoethane sulphonate as biomarker for methanogens in soil by high performance liquid chromatography using UV detector

All methanogens, irrespective of their preferred carbon sources, form coenzyme M (Co-M: 2-mercaptoethane sulphonate) as an intermediate to produce methane (CH4). But the quantification of Co-M in soil is not done before. In this experiment, the method for quantifying Co-M was standardized by HPLC using UV detector and the values of Co-M were compared with CH4 emission flux and methanogen activity of soil. The objectives of this experiment were to standardize the Co-M quantification technique and to evaluate its feasibility as a biomarker for methanogens in soil. The Co-M was extracted from soil by rupturing the cell membrane of methanogens using lysis buffer. Trichloroacetic acid solution (0.5 M) and acetonitrile mixture (70: 30, v/v) was used as a mobile phase for measuring Co-M by HPLC at 270 nm. The precision of the method was more than 97% and 90.3 ± 8.1% of the added Co-M standard was recovered from soil by this method. The Co-M concentration in soil was varied at the different rice cultivation stages and the highest concentration of Co-M was recorded at the maximum CH4 emission period (60 days after seedling transplanting). Application of organic substrates significantly (P ≤ 0.05) increased methanogen activity and Co-M concentration in rice paddy soil. The conversion factor, 155.03 ± 14.20 μg CH4 produced mmol−1 Co-M d−1, could be used to calculate methanogen activity from Co-M concentration of soil. Based on these results, it could be proposed that the Co-M concentration could be used as a biomarker for methanogen activity and the above-mentioned method can be used for an easy but precise quantification of Co-M in soil.

Development of an enzyme-linked immunosorbent assay for the detection of gentamycin residues in animal-derived foods

An enzyme-linked immunosorbent assay (ELISA) was developed using a polyclonal antibody with high affinity and specificity for detecting gentamycin in animal-derived foods. The half-maximum inhibition concentration (IC50) and limit of detection (LOD, calculated as IC15) of the ELISA for gentamycin in phosphate buffer were 0.3 and 0.03 ng/ml, respectively. The assay showed low cross-reactivity with other aminoglycoside antibiotics except sisomycin (52.5%), which indicated that the assay had high specificity. The trichloroacetic acid solution was selected as extraction buffer for eight animal-derived foods to effectively eliminate the matrix effect and extract gentamycin. The recoveries for gentamycin from eight fortified food samples, at three concentrations of 8, 20, and 50 μg/kg, were ranged from 69% to 118% and the coefficients of variation were less than 12%. The LODs of this assay for gentamycin in eight chosen animal-derived foods were 3 μg/kg. The whole detecting process could be finished within 1.5 h. The ELISA allows for a rapid, sensitive, specific, accurate, and low-cost determination of gentamycin residues in animal-derived foods.

Determination of alendronate in low volumes of plasma by column-switching high-performance liquid chromatography method and its application to pharmacokinetic studies in human plasma

A sensitive and simple column-switching high-performance liquid chromatographic (HPLC) method with fluorescence detection was developed for the determination of alendronate in human plasma. Alendronate and pamidronate (internal standard, IS) in plasma including Na(2)EDTA were precipitated with sodium hydroxide and calcium chloride after deproteinization using 10% trichloroacetic acid solution. The precipitated alendronate and IS were reconstituted by sodium citrate and citric acid and then derivatized with 9-fluorenylmethyl chloroformate. The resulting solution was injected onto an HPLC system consisting of a pretreatment column and an analytical column, which were connected with a six-port switching valve. The assay was linear in the concentration range of 2-100 ng/mL in 1 mL of plasma with high precision and accuracy, and the limit of detection was 0.5 ng/mL. It was successfully applied to evaluate the pharmacokinetic parameters of alendronate in human volunteers following single oral administration. The mean value of maximum alendronate plasma concentration (C(max)) was 37.69 ng/mL, and the mean time to reach the C(max) (T(max)) was 1.08 h. The area under the plasma concentration-time curve (AUC) and elimination half-life (T(1/2)) were 106.48 ng/mL/h and 1.66 h, respectively.

SPARC Oppositely Regulates Inflammation and Fibrosis in Bleomycin-Induced Lung Damage

Fibrosis results from inflammatory tissue damage and impaired regeneration. In the context of bleomycin-induced pulmonary fibrosis, we demonstrated that the matricellular protein termed secreted protein acidic and rich in cysteine (SPARC) distinctly regulates inflammation and collagen deposition, depending on its cellular origin. Reciprocal Sparc(-/-) and wild-type (WT) bone marrow chimeras revealed that SPARC expression in host fibroblasts is required and sufficient to induce collagen fibrosis in a proper inflammatory environment. Accordingly, Sparc(-/-) >WT chimeras showed exacerbated inflammation and fibrosis due to the inability of Sparc(-/-) macrophages to down-regulate tumor necrosis factor production because of impaired responses to tumor growth factor-β. Hence, the use of bone marrow cells expressing a dominant-negative form of tumor growth factor-β receptor type II under the monocyte-specific CD68 promoter, as a decoy, phenocopied Sparc(-/-) donor chimeras. Our results point to an unexpected dual role of SPARC in oppositely influencing the outcome of fibrosis.

Inhibitive efficiency of sulphathiazole for aluminum corrosion in trichloroacetic acid

PurposeThe purpose of this paper is to investigate the effect that different concentrations of the inhibitor sulphathiazole have on the corrosion of aluminum in 0.01, 0.05 and 0.10 M trichloroacetic acid (TCA), and to elucidate the mechanisms of inhibition for this system.Design/methodology/approachGravimetric measurements and galvanostatic polarization were used to investigate the effect of sulphathiazole on the corrosion of aluminum in TCA solution. The findings were used to determine the corrosion rates and efficiencies of the inhibitor at different concentrations.FindingsThe corrosion rate of aluminum decreased with increasing inhibitor concentrations and the efficiency of inhibition increased with increasing concentration of inhibitor up to almost 89 percent in 0.01 M TCA and up to 65.87 percent in 0.10 M TCA. The concentrations of inhibitor were in the range of 5‐20 mM. Absorption of the inhibitor was onto the aluminum surface and consistent with the Langmuir adsorption isotherm. A plot of log (θ/1−θ) versus log C gave a straight line, which suggests that the inhibitor covers both the anodic and cathodic regions. From the plot of the isotherm, it was observed that one inhibitor molecule occupies more than one active site. The mean ΔGads0 values were negative almost in all cases, indicating that the adsorption was spontaneous and that the mechanism of adsorption was physical – i.e. electrostatic attraction. Polarization data revealed that the inhibitor functions as a mixed inhibitor.Originality/valueThe paper deals with the inhibition of corrosion of 2S commercially pure aluminum in 0.01, 0.05 and 0.10 M solutions of TCA. To date, not much detailed information has been generated about this problem.

The comparison between trichloroacetic acid 50% and CO2laser in the treatment of cutaneous leishmaniasis scar

Background:The scars of the cutaneous leishmaniasis and psychological problems of this disease need different interventions for its correction.Aim:Our objective in this study was to compare the efficacy of 50% trichloroacetic acid (TCA) solution and CO2 laser for treatment of the atrophic scars due to leishmaniasis.Materials and Methods:This was a randomized clinical trial performed in 92 patients. Patients were randomized into two groups: the first group was treated with 50% TCA solution, once monthly and for a maximum of 5 months, and the second group was treated with CO2 laser which was performed for only one time. Patients were followed-up at 3 and 6 months after starting the treatment. The improvement of scar was graded by a 6-point scale using digital camera and the collected data were analyzed using SPSS software.Results:In this study, 74 females and 18 males were enrolled. The improvement of scar was 48.13% in the TCA group and 44.87% in the CO2 laser group. This difference was not statically significant (P = 0.55). There was also no significant difference regarding side effects between these two groups.Conclusion:The results of our study showed that efficacy of focal with 50% TCA solution is compared with CO2 laser in treatment of leishmaniasis scar. Because of the low cost and simple application of TCA solution in comparison with CO2 laser, we suggest use of this treatment for correction of leishmaniasis scar or the atrophic scars.

Sample Preparation for Determination of Neomycin in Swine Tissues by Liquid Chromatography-Fluorescence Detection

A liquid chromatography method was developed for the determination of neomycin in swine tissues. Sample clean-up was especially focused on in this research. After neomycin was extracted from tissue with 10% trichloroacetic acid (w/v) solution, several clean-up procedures using MCX, CBA, WCX, and C18 solid-phase extraction (SPE) columns were compared for the purification effects and recoveries. The best result was obtained using MCX SPE column. The purified extract was derivatized with 9-fluorenylmethyl chloroformate and then separated on a C18 column and detected by a fluorescence detector. The spiked recoveries at 0.2–10 mg/kg ranged from 80.8–95.3% with coefficient of variations less than 12.1%.

Multiclass, multiresidue method for the detection of antibiotic residues in distillers grains by liquid chromatography and ion trap tandem mass spectrometry

The increased production of ethanol in the US has resulted in large amounts of distillers grains (DG) which is an excellent feed supplement for livestock. However, the use of antimicrobials during ethanol fermentation has led to a growing concern over the possibility of their residues remaining in DG. To enable the detection of antimicrobial residues, a robust LC-MS/MS method was developed that included 13 antibiotics of diverse chemistries, ampicillin, penicillin G, tetracycline, oxytetracycline, chlortetracycline, bacitracin A, virginiamycin M1, chloramphenicol, erythromycin A, clarithromycin, tylosin A, monensin A and streptomycin. The residues were extracted with an aqueous solution of EDTA and trichloroacetic acid followed by methanol. The combined extract was subjected to a two-track cleanup and concentration on either hydrophilic polymeric or weak cation exchange solid phase extraction cartridges. The extracts are analyzed by LC/ion trap tandem mass spectrometry. The method was validated in dry DG matrix. Absolute recoveries of the analytes ranged from 50 to 100%. Accuracy ranged from 89 to 111% based on calibration by processed standards. The limits of detection and relative standard deviation are satisfactory to support future surveillance studies. The method was subsequently tested in three different end-products of DG: distillers dry grains, distillers wet grains and distillers grains solubles.

Chemical qualification of electrophoretically detectable peptides and sugar chains in oceanic surface particulate organic matter

Particulate organic matter (POM) is a mixture of living POM (organisms) and non-living POM (detritus). Since the majority of amino acids in organisms are comprised of proteins, and since the particulate combined amino acids (PCAAs) liberated by the acid hydrolysis of POM is the largest constituent of POM, PCAAs may be a mixture of proteins in organisms and their degradation products in detritus. However, the early stage of degradation and chemical alteration of proteins and the processes by which proteins in organisms are transferred to detrital PCAAs have not been well documented. Here we use gel chromatography (SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis) to chemically characterize the PCAAs pool and the following results were obtained. 1) The protein/peptide-specific dye (Coomassie brilliant blue; CBB) stainable materials (CSM) and the sugar chain-specific periodic acid Schiff (PAS) stainable materials (PSM) were simultaneously detected on POM electrophoretograms from the Antarctic to the Tropical Zone. 2) CSM and PSM showed electrophoretograms very similar to each other, in that they exhibited a smeared-staining pattern with a broad molecular weight range on the SDS-PAGE gel. Nevertheless, they did not covalently bind each other, and they were roughly separated using the solubility of trichloroacetic acid (TCA) solution. 3) Results obtained from the combination of enzymatic and chemical deglycosylation experiments, solubility in TCA solution, and SDS-PAGE revealed that CSM might be a conglomeration of proteins/peptides of various organisms in POM, while PSM might be comprised of degradation products of glycoconjugates. Carbohydrate-rich remnants with small-sized peptide chains derived from O-linked glycoproteins and/or proteoglycans were considered to be the most likely chemical form of PSM. The possible roles of such sugar chains in marine environments are discussed.

Sonoelectrochemical treatment of water polluted with trichloroacetic acid: From sonovoltammetry to pre-pilot plant scale

The sonoelectrochemical treatment of aqueous solutions of trichloroacetic acid (TCAA) has been scaled-up from the voltammetric analysis to pre-pilot stage. The degradation in absence of ultrasound field has yield to a poor performance which has been improved in presence of ultrasound. The sonovoltametry study has provided the range of potentials and/or current densities to be used with the lowest current efficiency penalty. Sonoelectrolyses at batch scale (carried out with a horn-transducer 24 kHz positioned at about 3 cm from the surface of the electrode) achieved little improvement in the degradation. However, when a specifically designed sonoelectrochemical reactor (not optimized) was used during the scale-up, the presence of ultrasound field provided better results (fractional conversion 97%, degradation efficiency 26%, selectivity 0.92 and current efficiency 8%) at lower ultrasonic intensities and volumetric flow.

Validation of a confirmatory method for the determination of melamine in egg by gas chromatography–mass spectrometry and ultra-performance liquid chromatography–tandem mass spectrometry

A sensitive and reliable method was developed and validated for detection and confirmation of melamine in egg based on gas chromatography–mass spectrometry (GC–MS) and ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS). Trichloroacetic acid solution was used for sample extraction and precipitation of proteins. The aqueous extracts were subjected to solid-phase extraction by mixed-mode reversed-phase/strong cation-exchange cartridges. Using ultra-performance liquid chromatography and electrospray ionization in the positive ion mode, melamine was determined by LC–MS/MS, which was completed in 5 min for each injection. For the GC–MS analysis, extracted melamine was derivatized with N, O-bis(trimethylsilyl)trifluoracetamide prior to selected ion monitoring detection in electron impact mode. The average recovery of melamine from fortified samples ranged from 85.2% to 103.2%, with coefficients of variation lower than 12%. The limit of detection obtained by GC–MS and UPLC–MS/MS was 10 and 5 μg kg −1, respectively. This validated method was successfully applied to the determination of melamine in real samples from market.

A New Generation of Peptide-based Inhibitors Targeting HIV-1 Reverse Transcriptase Conformational Flexibility

The biologically active form of human immunodeficiency virus (HIV) type 1 reverse transcriptase (RT) is a heterodimer. The formation of RT is a two-step mechanism, including a rapid protein-protein interaction "the dimerization step," followed by conformational changes "the maturation step," yielding the biologically active form of the enzyme. We have previously proposed that the heterodimeric organization of RT constitutes an interesting target for the design of new inhibitors. Here, we propose a new class of RT inhibitors that targets protein-protein interactions and conformational changes involved in the maturation of heterodimeric reverse transcriptase. Based on a screen of peptides derived from the thumb domain of this enzyme, we have identified a short peptide P(AW) that inhibits the maturation step and blocks viral replication at subnanomolar concentrations. P(AW) only binds dimeric RT and stabilizes it in an inactive/non-processive conformation. From a mechanistic point of view, P(AW) prevents proper binding of primer/template by affecting the structural dynamics of the thumb/fingers of p66 subunit. Taken together, these results demonstrate that HIV-1 RT maturation constitutes an attractive target for AIDS chemotherapeutics.

Quantifying Protein in Cerebrospinal Fluid and Urine: Success Achieved

Featured Article: Pesce MA, Strande CS. A new micromethod for determination of protein in cerebrospinal fluid and urine. Clin Chem 1973;11:1265–7.1 This paper described a dye-binding micromethod for measuring protein concentrations in cerebrospinal fluid and urine. The method involved coprecipitation of the proteins with a Ponceau S dye trichloroacetic acid solution, dissolving the protein precipitate in dilute sodium hydroxide, and measuring the absorbance at 560 nm. This method was rapid, easy to use, and required a specimen volume of 5–50 μL. I began my career as a clinical chemist in 1971 in the pediatric microchemistry laboratory at Columbia Presbyterian Medical Center. This laboratory served the newborn, infant, and child population of Babies Hospital, …

Efficacy and safety of cryotherapy vs. trichloroacetic acid in the treatment of solar lentigo

Solar lentigines are common sun-induced benign melanocytic proliferation that presents a significant cosmetic worrying for many middle-aged and elderly patients. Although the newer photoselective lasers have become the mainstay of treatment, cryotherapy and trichloroacetic acid (TCA) solution are inexpensive alternatives in the treatment of solar lentigines. The purpose of this study was to assess the efficacy of cryotherapy compared with TCA 33% on solar lentigines of the back of the hands (SLBH) in patients presenting to dermatologic clinic of our hospital. Each hand of 25 women with SLBH was treated randomly with either cryotherapy or TCA 33% solution. Photographs of the hands were taken prior to and 2 months following the treatment. The response and side- effect rate were compared. Cryotherapy was more likely to produce substantial lightening of the solar lentigines than TCA 33% solution (P = 0.025) but more painful and took more time to heal. Post-inflammatory hyperpigmentation (PIH) was almost equal in two types of treatment (P > 0.05). Statistically, the better results were seen in fairer Fitzpatrick's skin types (P = 0.00). Cryotherapy shows better results than TCA 33% solution in the treatment of SLBH particularly in lower Fitzpatrick skin types. PIH is the major complication of each type of treatments particularly in darker Fitzpatrick skin types. Generally, the major criterion for treatment of SLBH with cryotherapy or TCA is Fitzpatrick's skin type of patients.

Dynamic Scaffolding in a G Protein-Coupled Signaling System

The INAD scaffold organizes a multiprotein complex that is essential for proper visual signaling in Drosophila photoreceptor cells. Here we show that one of the INAD PDZ domains (PDZ5) exists in a redox-dependent equilibrium between two conformations--a reduced form that is similar to the structure of other PDZ domains, and an oxidized form in which the ligand-binding site is distorted through formation of a strong intramolecular disulfide bond. We demonstrate transient light-dependent formation of this disulfide bond in vivo and find that transgenic flies expressing a mutant INAD in which PDZ5 is locked in the reduced state display severe defects in termination of visual responses and visually mediated reflex behavior. These studies demonstrate a conformational switch mechanism for PDZ domain function and suggest that INAD behaves more like a dynamic machine rather than a passive scaffold, regulating signal transduction at the millisecond timescale through cycles of conformational change.

Plasma ascorbic acid preparation and storage for epidemiological studies using TCA precipitation

Objectives: To introduce a procedure to validate an ascorbic acid method using trichloroacetic acid (TCA) for plasma stabilization at different storage temperatures. Methods: EDTA and heparin plasma were precipitated with TCA (1:5) containing 0.54 mol/L EDTA, or without. Samples were stored at − 20 °C and − 70 °C and their stability was tested at room temperature for 24 h. Results: A significant 40% loss ( p < 0.001) of plasma ascorbic acid was found when EDTA samples with added EDTA were stored at − 20 °C for 2–4 weeks compared with storage at − 70 °C. Ascorbic acid in heparin plasma without added EDTA was most unstable and samples left at room temperature for 24 h lead to almost a total loss of ascorbic acid. Addition of EDTA to the TCA solution improved stability of samples of both plasma types at room temperature. Conclusion: The recommended procedure for ascorbic acid determination in plasma stabilized with TCA is immediate storage at − 70 °C and inclusion of EDTA into the TCA solution.

Quantitative determination of dihydrostreptomycin in bovine tissues and milk by liquid chromatography‐ electrospray ionization‐tandem mass spectrometry

Dihydrostreptomycin (DHS) is an aminoglycoside antibiotic used in veterinary medicine in combination with benzylpenicillin for the treatment of bacterial infections in cattle, pigs and sheep. A method to determine its residues in edible tissues of cattle, as well as in milk, was developed and validated. Extraction of DHS from the tissues was performed using a liquid extraction with a 10 mM phosphate buffer containing 2% (w/v) trichloroacetic acid, while milk samples were treated with a 50% (w/v) trichloroacetic acid solution, followed by a solid-phase clean-up procedure on a carboxypropyl (CBA) weak cation exchange column. Ion-pair chromatography, using a mixture of 20 mM pentafluoropropionic acid in water and acetonitrile as the mobile phase, was used to retain DHS and the internal standard streptomycin (STR) on a Nucleosil (5 microm) reversed-phase C18 column. The components were detected and quantified by electrospray ionization (ESI) tandem mass spectrometry. The method could be validated according to EC (European Community) requirements with respect to linearity, trueness and precision, the latter evaluated at the maximum residue limit (MRL) - 1000 ng g(-1) for kidney, 500 ng g(-1) for muscle, liver and fat, and 200 ng g(-1) for milk -, at one-half of the MRL and at one and a half times the MRL. A limit of quantification of 10 ng g(-1) and 1 ng ml(-1) was obtained for all tissues and for milk, respectively, which is far below one-half of the MRL as requested, while the limit of detection was in the low ppb range, varying between 1.9 and 4.2 ng g(-1) for the different tissues tested, and being 0.6 ng ml(-1) for milk. The method was used for the monitoring of DHS residues in incurred tissue and milk samples coming from cattle medicated with DHS in combination with benzylpenicillin by intramuscular injection, in order to evaluate withdrawal times.

Salicylates Trigger Protein Synthesis Inhibition in a Protein Kinase R-like Endoplasmic Reticulum Kinase-dependent Manner

The non-steroidal anti-inflammatory drug aspirin and its metabolite, sodium salicylate, have profound effects on cellular protein synthesis and cell physiology. However, the underlying mechanism by which they cause these responses remains unclear. We show here that salicylates induce phosphorylation of the alpha-subunit of eukaryotic translation initiation factor 2 (eIF2alpha), resulting in the inhibition of mRNA translation in cells. Exposure of cells to acetyl salicylic acid resulted in strong activation of eIF2alpha stress-activated protein kinase R-like endoplasmic reticulum kinase (PERK). Analysis of fibroblasts with a targeted deletion of the perk gene revealed that PERK is indispensable for triggering the phosphorylation of eIF2alpha as well as the inhibition of protein synthesis induced by salicylates. Although salicylate treatment did not trigger activation of inositol-requiring enzyme 1, there was an increased expression of the pro-apoptotic transcription factor CHOP-(gadd153), a downstream event to eIF2alpha phosphorylation known to mediate endoplasmic reticulum stress-mediated responses. Thus, salicylates selectively trigger an endoplasmic reticulum stress-responsive signaling pathway initiated through activation of PERK to induce their cellular effects.

X-ray crystal structure and spectral analyses of nonlinear opticall-lysinium trichloroacetate single crystals

Single crystal X-ray diffraction analysis was carried out on a new nonlinear optical L-lysinium trichloroacetate single crystal. The crystals were obtained from the combination of aqueous solutions of trichloroacetic acid and L-lysine by slow evapora