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PubMed1996

Resorbable polyesters in cartilage engineering: affinity and biocompatibility of polymer fiber structures to chondrocytes.

The resorbable polymers polyglycolic acid (PGA) and polylactic acid (PLA) are gaining increasing importance in tissue engineering and cell transplantation. The present investigation was focused on the biocompatibility and cell retaining behavior of PGA/poly-L-lactide (PLLA) (90/10) and PLLA nonwoven structures for the in vitro development of chondrocyte-polymer constructs. The effect of the relevant monomers to chondrocytes was analyzed. Type II collagen and poly-L-lysine were compared to improve loading of PGA/PLLA and PLLA polymer nonwovens with chondrocytes. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetra-zoliumbrom ide (MTT) test was applied for quantification. At concentrations above 2 mg/mL, glycolic acid was more cytotoxic than lactic acid. As shown by pH equilibration, the cytotoxic effect is not due merely to the acidity of the alpha-hydroxy acids. Regarding the degradation products, glycolic acid, and L(+) lactic acid, nonwovens of PLLA are more biocompatible with chondrocytes than nonwovens of polyglycolide. Collagen type II and poly-L-lysine generally improved cell seeding on resorbable polymers in tissue engineering; however, their efficiency varies depending on the type of fiber structure.

Adult↗

PubMed1996

In situ heterogeneity of peroxisomal oxidase activities: an update.

Oxidases are a widespread group of enzymes. They are present in numerous organisms and organs and in various tissues, cells, and subcellular compartments, such as mitochondria. An important source of oxidases, which is investigated and discussed in this study, are the (micro)peroxisomes. Oxidases share the ability to reduce molecular oxygen during oxidation of their substrate, yielding an oxidized product and hydrogen peroxide. Besides the hydrogen peroxide-catabolizing enzyme catalase, peroxisomes contain one or more hydrogen peroxide-generating oxidases, which participate in different metabolic pathways. During the last four decades, various methods have been developed and elaborated for the histochemical localization of the activities of these oxidases. These methods are based either on the reduction of soluble electron acceptors by oxidase activity or on the capture of hydrogen peroxide. Both methods yield a coloured and/or electron dense precipitate. The most reliable technique in peroxisomal oxidase histochemistry is the cerium salt capture method. This method is based on the direct capture of hydrogen peroxide by cerium ions to form a fine crystalline, insoluble, electron dense reaction product, cerium perhydroxide, which can be visualized for light microscopy with diaminobenzidine. With the use of this technique, it became clear that oxidase activities not only vary between different organisms, organs, and tissues, but that heterogeneity also exists between different cells and within cells, i.e. between individual peroxisomes. A literature review, and recent studies performed in our laboratory, show that peroxisomes are highly differentiated organelles with respect to the presence of active enzymes. This study gives an overview of the in situ distribution and heterogeneity of peroxisomal enzyme activities as detected by histochemical assays of the activities of catalase, and the peroxisomal oxidases D-amino acid oxidase, L-alpha-hydroxy acid oxidase, polyamine oxidase and uric acid oxidase.

Animals↗

PubMed1985

Effect of clomiphene on the content of sterols and fatty acids in Saccharomyces cerevisiae.

During cultivation of Saccharomyces cerevisiae clomiphene regulates both quantitative and qualitative production of sterols and fatty acids as identified by gas chromatography and mass spectrometry. The content of sterols decreases to 75%, the production of fatty acids is comparable with that in the control. The occurrence of sterols increases; sterols with methyl group in position 4, without double bond in position 22 and with double bond in position 24(25) or 24(28) predominate. Among fatty acids shorter saturated and monoene acids are primarily produced, 2-hydroxy acids practically disappeared.

Clomiphene↗

PubMed2002

Chemically modified chiral monolithic silica column prepared by a sol-gel process for enantiomeric separation by micro high-performance liquid chromatography.

In this work a new type of chiral monolith silica column was developed for the chiral separation by micro high-performance liquid chromatography (micro-HPLC). The chiral monolith column with a continuous skeleton and a large through-pore structure was prepared inside a capillary of 100 microm I.D. by a sol-gel process, and chemically modified with chiral selectors, such as L-phenylalaninamide, L-alaninamide and L-prolinamide, on the surface of the monolithic silica column. Based on the principle of ligand exchange, these chiral monolithic columns were successfully used for the separation of dansyl amino acid enantiomers, as well as hydroxy acid enantiomers by micro-HPLC. The chromatographic conditions, the enantioselectivity and the performance of columns are discussed.

Buffers↗

PubMed1988

Thin-layer chromatographic enantiomeric resolution via ligand exchange.

A thin-layer chromatographic technique for the separation of proteinogenic and non-proteinogenic amino acids, dipeptides and alpha-hydroxy acids is described. Other examples are given from the field of alpha-methyl, N-alkyl and halogenated amino acids. The separation of the enantiomers is achieved, without derivatization, by means of ligand exchange on a reversed-phase silica gel as stationary phase, which is covered with a chiral selector (proline derivative). The resolution is so good that the respective enantiomers can be determined at trace levels (greater than or equal to 0.25%). The proposed method is simple, inexpensive and needs no sophisticated instruments.

Amino Acids↗

PubMed2003

Determination of simvastatin-derived HMG-CoA reductase inhibitors in biomatrices using an automated enzyme inhibition assay with radioactivity detection.

A robust, automated enzyme inhibition assay method was developed and validated for the determination of HMG-CoA reductase inhibitory activities in plasma and urine samples following simvastatin (SV) administration. The assay was performed on Tecan Genesis 150 and 200 systems equipped with 8-probe and 96-well plates. Plasma samples containing HMG-CoA reductase inhibitors were treated with acetonitrile for protein precipitation before being incubated with HMG-CoA reductase, [14C]-HMG-CoA, and NADPH for a fixed length of time at a fixed temperature. The product, [14C]-mevalonic acid, was lactonized and separated from excess substrate via a small ion exchange resin column, and radioactivity was counted on a scintillation counter. HMG-CoA reductase inhibitors were measured before and after base hydrolysis. The two values obtained for each sample are referred to as 'active' and 'total' HMG-CoA reductase inhibitor concentrations. Simvastatin acid (SVA), the beta-hydroxy acid of SV, was used as a standard to generate a calibration curve of HMG-CoA reductase activity versus SVA concentration (ng/ml). Three calibration ranges, 0.4-20, 2-50, and 50, 100 ng/ml, in human and animal plasma and urine were validated. The assay precision was less than 8.5%, CV in plasma and less than 10.4% in urine. The assay accuracy was 93.6-103.0 and 98.1-103.9% for the 0.4 20 and 2-50 ng/ml calibration ranges, respectively, in human plasma, and was 97.3-105.1, 94.4- 105.2, and 90.2-95.7%, for calibration range 5-100 ng/ml in rat plasma, dog plasma and human urine, respectively.

Animals↗

PubMed1968

Some metabolites of 1-bromobutane in the rabbit and the rat.

1. Rabbits and rats dosed with 1-bromobutane excrete in urine, in addition to butylmercapturic acid, (2-hydroxybutyl)mercapturic acid, (3-hydroxybutyl)mercapturic acid and 3-(butylthio)lactic acid. 2. Although both species excrete both the hydroxybutylmercapturic acids, only traces of the 2-isomer are excreted by the rabbit. The 3-isomer has been isolated from rabbit urine as the dicyclohexylammonium salt. 3. 3-(Butylthio)lactic acid is formed more readily in the rabbit; only traces are excreted by the rat. 4. Traces of the sulphoxide of butylmercapturic acid have been found in rat urine but not in rabbit urine. 5. In the rabbit about 14% and in the rat about 22% of the dose of 1-bromobutane is excreted in the form of the hydroxymercapturic acids. 6. Slices of rat liver incubated with S-butylcysteine or butylmercapturic acid form both (2-hydroxybutyl)mercapturic acid and (3-hydroxybutyl)mercapturic acid, but only the 3-hydroxy acid is formed by slices of rabbit liver. 7. S-Butylglutathione, S-butylcysteinylglycine and S-butylcysteine are excreted in bile by rats dosed with 1-bromobutane. 8. Rabbits and rats dosed with 1,2-epoxybutane excrete (2-hydroxybutyl)mercapturic acid to the extent of about 4% and 11% of the dose respectively. 9. The following have been synthesized: N-acetyl-S-(2-hydroxybutyl)-l-cysteine [(2-hydroxybutyl)mercapturic acid] and N-acetyl-S-(3-hydroxybutyl)-l-cysteine [(3-hydroxybutyl)mercapturic acid] isolated as dicyclohexylammonium salts, N-toluene-p-sulphonyl-S-(2-hydroxybutyl)-l-cysteine, S-butylglutathione and N-acetyl-S-butylcysteinyl-glycine ethyl ester.

Alkanes↗

PubMed1981

Liver microsomal cytochrome P-450 and the oxidative metabolism of arachidonic acid.

Arachidonic acid is oxidatively metabolized by rat liver microsomes at a rate of approximately 5 nmol per min per mg of protein at 25 degrees C. This reaction is dependent on the presence of NADPH and oxygen. Studies with various inhibitors indicate a role for membrane-bound cytochrome P-450 in the transformation of arachidonic acid to a mixture of hydroxy acid derivatives. The stoichiometry of the reaction conforms to that of a monooxygenase reaction--i.e., one mole of NADPH is oxidized per mole of oxygen utilized--suggesting a reaction mechanism different from that proposed for lipid peroxidation reactions. No evidence for the formation of prostaglandin-like metabolites was obtained. The diene character of some of the metabolites formed suggests another role for cytochrome P-450--i.e., participation in hydrogen abstraction reactions for the activation of various substrates.

Animals↗

PubMed2005

Lactic acid as a new therapeutic peeling agent in melasma.

BACKGROUND: Melasma is a common disfiguring skin problem. Multiple modalities have been used in the treatment of melasma, such as bleaching agents and chemical peels. Many chemicals have been used in the skin peeling for melasma, such as Jessner's solution and glycolic acid. Lactic acid is an alpha-hydroxy acid that has not been used before in chemical peeling of melasma. OBJECTIVE: The purpose of the present work is to evaluate the efficacy and safety of lactic acid in chemical peeling of melasma. METHODS: This study was conducted at the outpatient Department of Dermatology and Venereology, Baghdad Teaching Hospital, in the period between April 2001 and August 2002. Twenty patients with melasma were included in this study; 18 (90%) were female and 2 (10%) were male, with an age range from 24 to 38 years and a mean of 29 +/- 4.264 SD. Full clinical examination was done of all patients, including Wood's light. The severity of melasma was assessed by the Melasma Area Severity Index (MASI). Pure lactic acid, full strength (92%; pH 3.5), was used as a new peeling agent. The chemical peeling sessions were done every 3 weeks until the desired response was achieved, but not more than six sessions. Follow-up was carried out for 6 months after the last session. All patients had skin type IV; morphologic forms of melasma were a mask-like shape in seven patients (35%), a butterfly shape in nine patients (45%), and a horseshoe shape in 4 patients (20%). RESULTS: Eight patients defaulted from the study after the first session for unknown reasons. Twelve patients completed the study. Eleven patients were female (91.7%), and one patient was male (8.3%). Their ages ranged from 24 to 38 years, with a mean of 29.25 +/- 4.9 SD. Wood's light examination showed increased contrast in all patients (epidermal melasma). The number of sessions ranged from two to six. All 12 patients showed marked improvement, as calculated by the MASI score before and after treatment, and the response was highly statistically significant. No side effect was recorded in all treated patients. CONCLUSION: Lactic acid was found to be a new effective and safe peeling agent in the treatment of melasma.

Adult↗

PubMed2006

Lactic acid chemical peels as a new therapeutic modality in melasma in comparison to Jessner's solution chemical peels.

BACKGROUND: Many chemicals have been used in the skin peeling for melasma such as Jessner's solution and glycolic acid. Lactic acid is an alpha-hydroxy acid that has not been used before in chemical peeling of melasma. OBJECTIVE: The purpose of the present work was to evaluate the efficacy and safety of lactic acid in chemical peeling of melasma in comparison to Jessner's solution chemical peels. METHODS: This study was conducted at the Department of Dermatology and Venereology, Baghdad Hospital, in the period between April 2001 and August 2002. Thirty patients with melasma were included in this study. They were mostly of skin type IV according to Fitzpatrick's classification, 26 (86.67%) were women, and 4 (13.33%) were men, with an age range from 18 and 50 years (mean+/-SD, 33.53+/-6.96 years). Full clinical examination was done to all patients including Wood's light. The severity of melasma was assessed by MASI (Melasma Area Severity Index). Pure lactic acid full strength (92%, pH 3.5) was used as a new peeling agent on the left side of the face while Jessner's solution was applied to the right side of the face. The chemical peeling sessions were done every 3 weeks until the desired response was achieved. Follow-up was carried out for 6 months after the last session. RESULTS: Six patients were defaulted from the study after the first session for unknown reasons. Twenty-four patients completed the study. Twenty (83.33%) were women and four were men (16.67%). Wood's light examination showed increased contrast in all patients of mostly epidermal melasma. The number of sessions ranged from 2 to 5. All patients showed marked improvement as calculated by MASI score before and after treatment, and the response was highly statistically significant. No side effect was recorded in all treated patients. CONCLUSION: Lactic acid was found to be an effective and safe peeling agent in the treatment of melasma, and it was as effective as Jessner's solution.

Adult↗

PubMed2005

Feedback-resistant acetohydroxy acid synthase increases valine production in Corynebacterium glutamicum.

Acetohydroxy acid synthase (AHAS), which catalyzes the key reactions in the biosynthesis pathways of branched-chain amino acids (valine, isoleucine, and leucine), is regulated by the end products of these pathways. The whole Corynebacterium glutamicum ilvBNC operon, coding for acetohydroxy acid synthase (ilvBN) and aceto hydroxy acid isomeroreductase (ilvC), was cloned in the newly constructed Escherichia coli-C. glutamicum shuttle vector pECKA (5.4 kb, Km(r)). By using site-directed mutagenesis, one to three amino acid alterations (mutations M8, M11, and M13) were introduced into the small (regulatory) AHAS subunit encoded by ilvN. The activity of AHAS and its inhibition by valine, isoleucine, and leucine were measured in strains carrying the ilvBNC operon with mutations on the plasmid or the ilvNM13 mutation within the chromosome. The enzyme containing the M13 mutation was feedback resistant to all three amino acids. Different combinations of branched-chain amino acids did not inhibit wild-type AHAS to a greater extent than was measured in the presence of 5 mM valine alone (about 57%). We infer from these results that there is a single binding (allosteric) site for all three amino acids in the enzyme molecule. The strains carrying the ilvNM13 mutation in the chromosome produced more valine than their wild-type counterparts. The plasmid-free C. glutamicum DeltailvA DeltapanB ilvNM13 strain formed 90 mM valine within 48 h of cultivation in minimal medium. The same strain harboring the plasmid pECKAilvBNC produced as much as 130 mM valine under the same conditions.

Acetolactate Synthase↗

PubMed1989

Subgrouping of Pseudomonas cepacia by cellular fatty acid composition.

The cellular fatty acid compositions were determined for 42 strains of Pseudomonas cepacia from five cystic fibrosis centers in North America. All isolates contained significant (20%) amounts of hexadecanoic (C16:0), and cis-9 hexadecenoic (C16:1 cis9) acids and an isomer of octadecenoic acid (C18:1). None had hydroxy acids containing fewer than 14 carbon atoms. The quantitative data from the fatty acid analysis were highly reproducible and provided a basis for numerical analysis. Five subgroups comprising all the strains were obtained by cluster analysis and further characterized by principal-component analysis. With minor exceptions, the predominant subgroup identified in each center was different from that identified in other centers and accounted for one-half of the isolates within each center. Cellular fatty acid composition is a useful adjunct to biochemical characterization for the identification of P. cepacia isolated from cystic fibrosis patients. Numerical analysis of the fatty acid data can separate P. cepacia into subgroups, which may provide useful epidemiologic information or a basis for further analysis by more complex techniques such as DNA probe analysis.

Bacterial Typing Techniques↗

PubMed2003

Less common methods to treat acne.

Effective medications to treat acne sometimes become unavailable in certain countries, either for economic reasons or for shortage of them in the pharmaceutical market. The purpose of this report is to review a series of drugs of topical and systemic use; some old and some new. The topical group includes agents such as sulfur, salicylic acid and the alpha-hydroxy acids, while the systemic group includes diaminodiphenylsulfone, clofazimine, ibuprofen and others. Some presumably useful physical methodologies and the recent findings in phototherapy, particularly the properties of blue light and blue-red light, are also reviewed. Finally, we report on the results obtained from the combined use of isotretinoin and methylprednisone in severe inflammatory acne, to prevent a possible triggering of the 'pseudo' acne fulminans.

Acne Vulgaris↗

PubMed2000

Probing the role of a conserved M1 proline residue in 5-hydroxytryptamine(3) receptor gating.

A conserved proline residue is found in the first transmembrane domain (M1) of every subunit in the ligand-gated ion channel superfamily. The position of this proline between the N-terminal extracellular agonist binding and the second transmembrane (M2) channel lining domains in the primary sequence suggests its possible involvement in the gating of the receptor. Replacing this proline with alanine, glycine, or leucine in the 5-hydroxytryptamine (5-HT)(3A) homomeric receptors expressed in Xenopus laevis oocytes resulted in the absence of 5-HT-induced whole-cell currents, although there were normal levels of specific surface [(3)H]granisetron ([(3)H]BRL-43694) binding sites. To determine what properties of the conserved proline are critical for the function of the channel, two imino acids and an alpha-hydroxy acid were incorporated at the proline position using the nonsense suppression method. trans-3-Methyl-proline, pipecolic acid, and leucic acid were able to replace the conserved proline to produce active channels with EC(50) values similar to that for the wild-type receptor. These trends are preserved in the heteromeric receptors consisting of 5-HT(3A) and 5-HT(3B) subunits in oocytes. The prominent common feature among these residues and proline is the lack of hydrogen bond donor activity, potentially resulting in a flexible secondary structure in the M1 region. Thus, lack of hydrogen bond donor activity may be a key element in channel gating and may explain the high degree of conservation of this M1 proline.

Animals↗

PubMed2002

[Xerosis].

The clinical characteristic of xerosis is rough or coarse skin. Physiopathologically, the structure of the stratum corneum is modified and abnormalities in keratinization, proliferation, surface lipid, water metabolism and also pH and sebum exist. There are two forms of xerosis: dry skin forms and ichtyosis or ichtyosis-like forms. Xerosis has many etiologies including external aggression, senescence, drugs, infection, atopy, deficiencies, malignant diseases, endocrine affections, eating disorders and renal failure in dialyzed patients. It provokes cutaneous discomfort and unaesthetic appearance that justify appropriate treatment. Treatment is essentially local, symptomatic and must be accompanied by general measures. Many products include moisturizers and emollients (keratolytics: salicylic acid, urea and alpha-hydroxy acid).

Dermatologic Agents↗

PubMedDate not supplied

Targeted delivery of salicylic acid from acne treatment products into and through skin: role of solution and ingredient properties and relationships to irritation.

Salicylic acid (SA) is a beta hydroxy acid and has multifunctional uses in the treatment of various diseases in skin such as acne, psoriasis, and photoaging. One problem often cited as associated with salicylic acid is that it can be quite irritating at pH 3-4, where it exhibits the highest activity in the treatment of skin diseases. We have identified strategies to control the irritation potential of salicylic acid formulations and have focused on hydroalcoholic solutions used in acne wipes. One strategy is to control the penetration of SA into the skin. Penetration of the drug into various layers of skin, i.e., epidermis, dermis, and receptor fluid, was measured using a modified Franz in vitro diffusion method after various exposure times up to 24 hours. A polyurethane polymer (polyolprepolymer-15) was found to be an effective agent in controlling delivery of SA. In a dose-dependent fashion it targeted delivery of more SA to the epidermis as compared to penetration through the skin into the receptor fluid. It also reduced the rapid rate of permeation of a large dose of SA through the skin in the first few hours of exposure. A second strategy that proved successful was incorporation of known mild nonionic surfactants like isoceteth-20. These surfactants cleanse the skin, yet due to their inherent mildness (because of their reduced critical micelle concentration and monomer concentration), keep the barrier intact. Also, they reduce the rate of salicylic acid penetration, presumably through micellar entrapment (either in solution or on the skin surface after the alcohol evaporates). Cumulative irritation studies showed that targeting delivery of SA to the epidermis and reducing the rapid early rate of penetration of large amounts of drug through the skin resulted in a reduced irritation potential. In vivo irritation studies also showed that the surfactant system is the most important factor controlling irritancy. SA delivery is secondary, as formulations with less SA content reduced the rate of delivery to the receptor and yet were some of the most irritating formulations tested, presumably due to the action of the specific anionic surfactant on the barrier. Alcohol content also did not appreciably affect irritation and SA delivery; formulations with considerably lower alcohol content but containing anionic versus nonionic surfactant systems exhibited considerably higher irritancy. Thus the surfactant type was again the predominant factor in those studies, although arguably alcohol plays some role (solubilization of SA). Results showed that both polymers and mild surfactants work in concert to provide the optimal formulation benefits of targeted delivery and reduced irritation. Synergistic relationships among hydroalcoholic formulation components will be discussed along with the mechanisms likely involved in controlling delivery of SA to skin.

Acne Vulgaris↗

PubMed1989

New potential immunoenhancing compounds. Synthesis and pharmacological evaluation of new long-chain 2-amido-2-deoxy-D-glucose derivatives.

A series of long-chain fatty acids and the corresponding 2-hydroxy, 2-oxo, 3-hydroxy acid glucosamides were evaluated as immunomodulating compounds. In a preliminary screening, 2-[(2-ethoxycarbonyloxy)tetradecanoylamino]-2-deoxy-D-glucos e (2b) and 2-(3-hydroxydodecanoylamino)-2-deoxy-D-glucose (5a) resulted to be the most effective in enhancing the glucosamine activity. The findings of in vitro-ex vivo tests (unidirectional mixed lymphocyte culture reaction and primary antibody production) and in vivo tests (delayed type hypersensitivity, protection against bacterial or fungal infection and against Sarcoma 180 or Lewis lung carcinoma transplants) were very encouraging and allowed to assume for the two substances a protective activity, presumably through the ability of activating phagocytic and NK cells.

Adjuvants, Immunologic↗

PubMed2004

Water molecules in hydroxy/acid networks as a competition between dynamics and bonding. Synthesis of a wet hydrophobic pore.

In a model formed by hydroxy acids with a general structure (+/-)-1, we found that solid-state structures depend on steric interactions. Thus, with the exception of molecules 1b and 1e, compounds (+/-)-1a-(+/-)-1m, which possess bulky and conformationally rigid substituents, aggregate by forming tapes and sheets by alternating (+) and (-) subunits held together via carboxylic acid to alcohol hydrogen bonds. Homologue (+/-)-1n with conformationally flexible substituents, which allow conformational deformation gives, by way of the incorporation of water molecules, an efficient hexagonal assembly, which extends to the third-dimension to form tubular H-bonding networks. Each puckered channel can be described as being interconnected by closely packed hexagons in chair-like conformations. The ethyl groups presented in (+/-)-1n provided the volume required to lock the inner hexagonal wall into a rigid structure.

Carboxylic Acids↗