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At least 883 records · Page 49Linked to original sources
PubMed2005

[A study of the applicability of biological adhesives to the reinsertion of an external ocular muscle in rabbits--I experiment I--measurements of duration of procedures, and clinical and histopathologic studies].

PURPOSE: To measure the duration of the operation, the strength of tissue adhesion, and to perform a clinical and histopathological study of ocular reinsertion of superior rectus muscles of rabbits with four different tissue adhesives, as an alternative to the use of polyglactin suture in strabismus surgeries. METHODS: One hundred New Zealand rabbits were used for two experiments: I-A and I-B, with fifty rabbits for each experiment. These groups were further divided into five groups of ten rabbits (twenty eyes), which were subjected to the removal of the superior rectus muscle of both eyes, either with suture (control) or tissue adhesive: polyglactin 910, 6-0 suture and tissue adhesives made of fibrin, cyanoacrylate, albumin-glutaraldehyde and gelatine-resorcinol-formaldehyde-glutaraldehyde. The rabbits in experiment I-A were subjected to dynamometry for ten minutes following repositioning of the muscle. The rabbits in experiment I-B were subjected to clinical evaluation and to histopathologic evaluation. RESULTS: Better performance of the tissue adhesives in relation to the time taken to carry out the surgery was observed. None of the adhesives met the parameters used for strength, that is, in some cases the reinserted muscle did not resist to the application of forces up to 100 gf. The clinical and histopathologic evaluations showed that only the fibrin adhesive presented a better performance than the polyglactin suture while the other results were worse than those of the controls (suture). CONCLUSION: It was observed that the adhesives studied are not suitable for strabismus surgeries.

Animals↗
PubMed2005

Oxytalan elastic and collagen fibers during the repair process in experimental nitric oxide inhibition.

PURPOSE: To evaluate the repair process in rats with experimentally induced arterial hypertension. This study aimed to evaluate lesions in the ventricular myocardium and the repair process during experimental hypertension induced by systemic blockage of nitric oxide using N-omega-nitro-L-arginine methyl ester hydrochloride (L-NAME). Nitric oxide is an endothelial vasorelaxing factor and is necessary for the maintenance of normal arterial pressure, and L-NAME is an analog and antagonist of L-arginine, the substrate of the nitric oxide synthase. MATERIALS AND METHODS: We used 26 normotensive young male Wistar rats belonging to several litters. Animals were treated with oral administration of L-NAME dissolved in water (75 mg/100 mL) for 43 days. Hearts were weighed and processed by routine methods. Special stains utilized were Gomori's trichrome (aniline blue), picrosirius red polarization to identify fibrillar collagen, alcian blue technique (pH 0.5 and pH 2.5) to identify glycosaminoglycans, periodic acid-Schiff technique (with and without amylases) to identify proteoglycans, and Weigert's resorcinol fuchsin solution (with and without oxone) to identify elastic fibers. RESULTS: The results showed significant elevation of the arterial pressure (P <0.01) and significant increase of cardiac weight (P <.0001) in the L-NAME (hypertensive) treated group, as compared to an untreated control group. The histological analysis demonstrated wide infarcted myocardial areas in animals with nitric oxide blockade; several vascular changes such as thickening of the muscular tunica with fibrosis; thickening in the wall of small arteries and arterioles; and fibrinoid necrosis in the wall to nearly complete luminal obliteration. Reparative fibrosis involved mainly oxytalan elastic and collagen fibers. CONCLUSION: Oxytalan elastic and collagen fibers are of great importance for the postinfarct repair process occurring during experimental nitric oxide inhibition.

Animals↗
PubMed2001

The use of water structure breakers, urea and guanidium chloride, new mobile phase modifiers in reversed-phase partition high-performance liquid chromatography.

Organic solvent-free mobile-phase systems in ion-pair reversed-phase partition high-performance liquid chromatography (IPRP-HPLC) are demonstrated; using urea at 3.0-7.0 molal (mol kg-1) as a modifier in a mobile phase on an octadecylsilanized silica column, four nitrophenolates and metal 4-(2-pyridilazo)resorcinol (PAR) chelates (in PAR chelates system an aqueous mobile phase with 15 wt% methanol was used) were separated rapidly within 6 min at no sacrifice to the separation efficiency. On the addition of urea in the mobile phase, reduced retention times of nitrophenolates and naphthalenesulfonates and also diminution of the height equivalent to a theoretical plate were observed. The addition of urea and guanidium chloride (GuCl) in the mobile phase gave rise to a decrease in the mobile phase volume; in turn, this meant an increased volume of the stationary phase. As the concentration of urea and GuCl in the mobile phase increased, the volume of the mobile phase in the column decreased within about 70% and 40% at 7.0 molal of urea and GuCl, respectively. A decrease in the mobile phase volume suggests an increase in the extent of solvation of the bonded hydrocarbon chain of the stationary phase. The possible explanations for the LC behavior with the urea and GuCl are turned into reduction of hydrophobic interaction in LC processes, solute partitioning and entangling of alkyl chain brushes, with the addition of urea. The water structure breakers, urea and GuCl, most likely affect the solvation states of both solute molecules and the hydrocarboneous stationary phase by changing the nature of the water solvent, which provides a new technique for fine tuning of the LC resolution of the analytes.

Anions↗
PubMed2002

Equilibrium analysis of reactions of metal-pyridylazoresorcinolato chelates with quaternary ammonium ion, nonionic surfactant and polyethylene glycol in aqueous solution by capillary zone electrophoresis.

The resolutions of metal-4-(2-pyridylazo)resorcinol chelates by capillary zone electrophoresis (CZE) were investigated in the presence of some interacting reagents; also, equilibrium reactions between the chelates and the interacting reagents were analyzed in an aqueous solution. Among nine metal chelates formed in aqueous solution, the chelates of VV, FeII, CoIII, NiII, and CuII were resolved and detected by CZE, while other chelates were decomposed during electrophoretic migration. The electrophoretic mobility of the chelates of FeII, NiII, and CuII increased with increasing pH of the migrating solution; also, the acid-dissociation constants of these three chelates were determined by analyzing the mobility change. The ion-association constants of the five anionic chelates and pyridylazoresorcinolate ion with quaternary ammonium ions were also determined by analyzing the mobility change. The binding behavior of the ligand and its chelates with nonionic surfactant micelle, as well as with polyethylene glycol, were investigated, and their binding constants were determined through the mobility change. When Brij 35 was used as a nonionic surfactant interacting with the anionic chelates, the FeII chelate decomposed at Brij 35 concentrations over 6.67 mM. The equilibrium constants and the reactivity were compared with each other.

Journal Article↗
PubMed2002

A simple and rapid in situ preconcentration method using solid-phase extraction for the determination of dissolved manganese in brackish lake water samples.

A simple and rapid in situ preconcentration method for the determination of dissolved manganese in environmental waters has been developed based on solid-phase extraction using a Sep-Pak C18 cartridge. Manganese in water samples, which was taken into a graduated syringe to easily perform the operation for collecting manganese at sampling sites, was converted into a stable complex with 4-(2-pyridylazo)resorcinol (PAR) at pH 10 immediately after sample collection. The formed Mn-PAR complex was collected by a Sep-Pak C18 cartridge, which was packed with C18-bonded silica. The complex was stable in the Sep-Pak C18 cartridge for at least one month. The retained complex was quantitatively eluted with 0.5 M hydrochloric acid. The manganese was determined by graphite-furnace AAS. The proposed method was successfully applicable to brackish lake water samples to investigate the behavior of dissolved manganese in brackish lakes.

Adsorption↗
PubMed2002

Enrichment and determination of zinc by high-speed countercurrent chromatography.

The capability of high-speed countercurrent chromatography (HSCCC) has been investigated for enrichment and determination of metal ions at trace levels. Separation of selected divalent metal ions was performed using a small coiled column. A hexane solution of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHPA) was employed as the stationary phase. Loaded divalent metal ions such as Ni, Co, Cu, and Zn were chromatographically eluted in the order of increasing extractability by passing a mobile phase buffered at a desired pH. Individual metal ions showed good linearity between concentrations and chromatographic peak areas of the absorbance, as detected by postcolumn reaction with 4-(2-pyridylazo)resorcinol (PAR). Metal ions enriched into the stationary phase from a sample solution were separated into individual metal ions. The trace quantity of zinc in natural mineral water was determined by enrichment separation through an HSCCC column.

Journal Article↗
PubMed2003

Selective measurement of gaseous hydrogen peroxide with light emitting diode-based liquid-core waveguide absorbance detector.

Atmospheric H2O2 is typically determined by enzymatically mediated fluorogenic reactions that do not discriminate between H2O2 and organic peroxides. Reactions of Ti(IV) with H2O2 has also been the basis of colorimetric measurements of H2O2 but is too insensitive. A more sensitive determination is possible with the Ti(IV)-4-(2-pyridylazo)resorcinol (PAR) complex, however, unreacted PAR must be chromatographically separated. A titanium(IV)porphyrin complex, oxo[5,10,15,20-tetra(4-pyridyl)porphyrinato]titanium(IV) [TiO(tpypH4)4+], (TiTPyP) was introduced for the measurement of aqueous H2O2. In this paper, we show that TiTPyP can be used for measuring H2O2(g)), it does not respond to CH3HO2. With a proper membrane collector, practically there is no interference from concurrently present gaseous SO2 and O3. The approach permits a S/N = 3 limit of detection (LOD) of 26 pptv with a 50 mm path liquid core waveguide (LCW) absorbance detector and a light emitting diode based light source. This is adequate for real atmospheric measurements.

Journal Article↗
PubMed2005

Separation and determination of trace amounts of aluminium(III), vanadium(V), iron(III), copper(II) and nickel(II) with CALKS and PAR by RP-HPLC.

An RP-HPLC method for the separation and determination of aluminium(III), vanadium(V), iron(III), copper(II) and nickel(II) with CALKS (Chromazol KS) and PAR ([4-(2-pyridylazo)resorcinol]) chelating on a YWG-ODS column was developed. A mixture of methanol-tetrahydrofuran(THF)-water (60:5:35 v/v) containing 0.2 mol/L LiCl, 5 x 10(-5) mol/L CALKS, 5 x 10(-5) mol/L PAR and acetate buffer solution (pH 4.9) was selected as mobile phase. The method has high sensitivity, with the detection limits being 6 ng/mL for aluminium(III), 3.5 ng/mL for vanadium(V), 10.4 ng/mL for iron(III), 6.3 ng/mL for copper(II) and 8.7 ng/mL for nickel(II). It also has good selectivity, so that most foreign metal ions do not interfere under the optimum conditions. The method can be applied to the simultaneous determination of trace amounts of aluminium, vanadium, iron, copper and nickel in rice and flour samples.

Journal Article↗
PubMed2005

Simultaneous determination of cobalt, copper and zinc by energy dispersive X-ray fluorescence spectrometry after preconcentration on PAR-loaded ion-exchange resin.

A sensitive method for the preconcentration and determination of trace amounts of Co, Cu and Zn by energy-dispersive X-ray fluorescence spectrometry (EDXRF) has been developed. The method is based on the fact that 4-(2-pyridylazo)-resorcinol (PAR) loaded Dowex anion-exchange resin (PAR-resin) can effectively adsorb Co, Cu and Zn at pH 9.0 to form PAR-metal complexes. The detection limits for Co, Cu and Zn were 1.53, 0.31 and 0.21 ppb, respectively. The precisions for five replicate measurements of the three metals were 3.4, 2.7 and 2.1% RSD, and the calibration curves were linear up to 75 microg with correlation coefficients of 0.9975, 0.9980 and 0.9985, respectively. The method was successfully applied for the simultaneous determination of Co, Cu and Zn in seawater samples at ppb levels.

Journal Article↗
PubMed2006

Separation of V(V)-4-(2-pyridylazo)resorcinolato complex from a large excess reagent using an ODS cartridge for high-performance liquid chromatography.

A selective off-line preconcentration technique for the V(V) complex with 4-(2-pyridylazo)resorcinol has been developed and successfully applied to the determination of V(V) in an air-borne sample. The target complex was separated from excess reagent using an ODS cartridge and water as the eluent. The complex was then concentrated on another ODS cartridge using tetrabutylammonium bromide and eluted with methanol; the eluate was applied to a one-drop concentration/HPLC. A detection limit as low as (6.05 +/- 0.82)x 10(-11) M (5 ppt) was achieved.

Journal Article↗
PubMed2002

Synchrotron radiation-induced X-ray emission to identify metal ions in preparations of purified protein.

The suitability of synchrotron radiation-induced X-ray emission (SRIXE) for the detection and identification of metal ions in preparations of purified, soluble proteins was tested. Glutathione S-transferase fused to the proximal zinc finger motif of human transcription factor IIIA or to the cysteine-rich motif of poliovirus protein 2C was expressed in bacteria and purified by affinity chromatography. Aqueous samples containing the purified proteins were analyzed with SRIXE, and trace amounts of zinc and iron were detected. Mutation of the zinc-coordinating residues in the cysteine-rich motif of poliovirus protein 2C resulted in the loss of the zinc-binding ability. Relative quantities of metal in the protein preparations as determined by SRIXE corresponded well with the metal:protein ratios calculated by using a 4-(2-pyridylazo)resorcinol-based assay. We conclude that SRIXE is an accurate, sensitive, and simple method for the detection and identification of protein-bound metal ions in small amounts of sample. Thus, SRIXE may have wide use as a particularly effective method for rapidly determining trace metals in microarray samples.

Amino Acid Sequence↗
PubMed1977

Vitamin A acid: a review of its pharmacological properties and therapeutic use in the topical treatment of acne vulgaris.

Vitamin A acid (retinoic acid: tretinoin) is a vitamin A derivative used in the topical treatment of acne. It acts by 'unseating' comedones, improvement developing slowly over a period of 2 to 3 or more months, and is also said to prevent the formation of new lesions. About three-quarters of patients with acne vulgaris benefit from treatment. In controlled studies, results achieved after a 3 to 4 months course of treatment were superior to those with sulphur-resorcinol-salicylic acid. When compared with benzoyl peroxide, results were variable and appear to depend on the length of treatment, the types of formulations used, and the concentrations compared. Application of vitamin A acid should be continued until the patient has been free of new lesions for several months. Further continued application at a less frequent interval or using a less active dosage form may help to prevent exacerbations of acne. A systemic antibacterial agent such as tetracycline can be given as well as in patients with moderate to severe lesions. Vitamin A acid is used in conjunction with gentle washing (to remove surface oil) but should be applied to a dry skin to avoid unnecessary irritation. Patient education and encouragement are crucial during the initial phase of treatment when microcomedones may be converted to pustules prior to desquamation.

Acne Vulgaris↗
PubMed1978

Fenoterol: a review of its pharmacological properties and therapeutic efficacy in asthma.

Fenoterol, the 4-hydroxyphenyl derivative of orciprenaline, is a resorcinol derivative with relatively high selectivity for beta2-adrenoceptors. It is active in man after inhalation or oral administration and is indicated in the treatment of bronchospasm associated with asthma, bronchitis and other obstructive airway diseases. Clinical experience has shown that fenoterol is an effective bronchodilator with negligible effects on the cardiovascular system following aerosol administration of usual therapeutic doses. In children, inhaled fenoterol is effective in preventing exercise-induced asthma and administration of the aerosol in young children has been successfully used to terminate acute asthma attacks. In trials in adults, inhaled fenoterol was superior to placebo. In other controlled studies, it showed a tendency to cause a slightly greater maximum improvement in airway function as assessed spirometrically, and to have a longer duration of action than inhaled orciprenaline, salbutamol or terbutaline, although in these trials statistically significant differences were often not found. The onset of maximum effect is less rapid than with isoprenaline but is longer lasting. About 60% of the eventual maximum response to fenoterol is reached in the first few minutes after inhalation. Oral fenoterol is more effective than placebo, ephedrine or orciprenaline, and probably similar to salbutamol and terbutaline. Following usual aerosol doses, side-effects are minimal. Oral administration is associated with a higher incidence of side-effects than inhalation, including fine muscle tremor and tachycardia.

Adolescent↗
PubMed2006

Discovery and development of pyrazole-scaffold Hsp90 inhibitors.

This review explains why the chaperone Hsp90 is an exciting protein target for the discovery of new drugs to treat cancer in the clinic, and summarises the properties of natural product derived inhibitors before relating the discovery and current state of development of synthetic pyrazole compounds. Blockade of Hsp90 results in reduced cellular levels of several proteins implicated in cancer including CDK4, ERBB2 and C-RAF, and causes simultaneous inhibition of cancer cell proliferation in culture and of tumor xenograft growth in vivo. Hsp90 has an ATPase domain that is necessary for its Hsp chaperone function, and X-ray crystallography has shown that natural product inhibitors (geldanamycin, radicicol) of Hsp90 function bind to this domain. High throughput assays focusing on the ATPase activity of Hsp90 were developed and used to discover novel chemical starting points for cancer drug discovery. The discovery, synthesis and SAR of 3,4-diaryl pyrazoles is described. X-Ray crystallography of protein-inhibitor complexes revealed important interactions involving the resorcinol substituent at C-3, and these X-ray structures strongly influenced subsequent medicinal chemistry research that has resulted in highly potent inhibitors with sub-micromolar activity in cells. SAR and X-ray data are summarised for analogues in which the 4-phenyl substituent is replaced by amides or piperazine derivatives. Prospects for the pyrazoles as they progress towards clinical development are discussed in relation to current Phase I trials with derivatives of geldanamycin.

Animals↗
PubMed1986

Dihydrochalcone metabolism in the rat: trihydroxylated derivatives related to phloretin.

The metabolism of 2',4',4-, 2',6',3- and 2',6',4-trihydroxydihydrochalcone was studied in rats. Approx. 25-35% of the oral dose (0.75 mmol/kg) was excreted in the urine during a five to six day period. The unchanged compounds were the most prominent urinary excretion products and were also present in large amounts in the faeces. Other metabolites of the three dihydrochalcones included minor amounts of hydroxylated products and subsequent O-methylated derivatives as well as minor amounts of degradation products (resorcinol and hydroxyphenylpropionic acids) arising from scission of the compounds by the normal gut microflora. The present results support the view that the degradative metabolism of dihydrochalcones involves scission leading to equal amounts of products derived from the A- and B-ring regions of these flavonoids.

Animals↗
PubMed1995

Porphyrin pi-cation and protein radicals in peroxidase catalysis and inhibition by anti-thyroid chemicals.

1. Thyroid peroxidase (TPO) catalyses the iodination and phenolic coupling reactions in the biosynthesis of thyroid hormones. 2. The two-electron oxidation of TPO by H2O2 produces an oxoferryl porphyrin pi-cation radical compound I that isomerizes spontaneously to a form of compound I that contains an oxoferryl haem and the second oxidizing equivalent as an amino acid radical. 3. The pi-cation radical compound I is the catalytic species that effects iodide ion oxidation and the protein radical compound I is most likely the catalytic species that catalyses coupling. 4. Methimazole, a therapeutic, anti-hyperthyroid drug, is a suicide substrate for TPO and effects irreversible inactivation by TPO-mediated S-oxygenation to a reactive sulphenic acid that binds covalently to the prosthetic haem. 5. Sulphamethazine and other arylamines containing electron-withdrawing substituents inhibit TPO compound I-mediated reactions by reversible, mixed-type inhibition. 6. Ethylenethiourea, a fungicide metabolite, blocks TPO-mediated iodination by reacting with the catalytic iodinating species as an alternate substrate. 7. Resorcinol and related dietary flavonoids are suicide substrates for TPO and act by covalent binding to amino acid residues, presumably those radical sites present in the compound I isomer. 8. Nitrosobenzene, a known radical-trapping agent, blocks TPO-mediated coupling but not iodination or phenolic oxidations presumably by interception of the 3,5-diiodotyrosyl radical species generated during the coupling reaction.

Animals↗
PubMed1981

Specific staining of sialic acid components on sodium dodecyl sulfate polyacrylamide gel.

Specific staining of sialic acid components after sodium dodecyl sulfate polyacrylamide gel electrophoresis can be carried out as follows: 1) extract glycoprotein of erythrocyte membranes or serum by the phenol-saline method, 2) electrophorese the extract on 5% polyacrylamide gel containing 0.1% sodium dodecyl sulfate at constant current, 3) treat the gel with chilled 0.04 M HIO4 for 45 minutes, 4) replace the periodic acid solution with one containing resorcinol 0.6 g, conc. HCl 50 ml, 0.1 M CuSO4 0.5 ml and H2O 50 ml, 5) warm the container in boiling water until blue violet sialic acid bands become clear, 6) replace the staining solution with a mixture of equal parts water and concentrated HCl and observe at once.

Amido Black↗
PubMed1986

Chlorantine fast green BLL as a stain for callose in oak phloem.

Sections of oak bark were stained with chlorantine fast green BLL, used as a 0.25% aqueous solution. All tissues were unstained, except for local deposits of material associated with phloem cell walls, which stained deep green. This green-staining material also stained specifically with resorcinol blue and with the aniline blue fluorescence technique, the usual histochemical tests for callose. The chlorantine fast green-staining material was removed from sections by treatment with a beta-1,3-glucan hydrolase. It is concluded that chlorantine fast green BLL stains callose in plant sections and is a useful additional stain for the histochemical detection of this polymer.

Azo Compounds↗