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At least 469 records · Page 26Linked to original sources
PubMed2005

Kinetic study of the quenching reaction of singlet oxygen by tea catechins in ethanol solution.

A kinetic study of the quenching reaction of singlet oxygen ((1)O(2)) with catechins (catechin (CA), epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), epigallocatechin gallate (EGCG)) and related compounds (5-methoxyresorcinol (MR), 4-methylcatechol (MC), and n-propyl gallate (PG)) was performed in ethanol at 35 degrees C. MR, MC, and PG are considered to be a model of resorcinol (A)-, catechol (B)-, and gallate (G)-rings in catechins, respectively. The overall rate constants, k(Q) (= k(q) + k(r), physical quenching + chemical reaction), for the reaction of catechins with (1)O(2) increased in the order of PG < MR < MC < CA < EC < EGC < ECG < EGCG. In a comparison of the rate constants, the relationship between quenching rates and chemical structures is discussed. The catechins which have lower peak oxidation potentials, E(P), show higher reactivities. It was observed that the chemical reaction (k(r)) is almost negligible in the quenching reaction of (1)O(2) by catechins. The k(Q) values of EGCG (1.47 x 10(8) M(-1) s(-1)) and ECG (7.81 x 10(7)) were found to be larger than those of lipids (1.3 x 10(5)-1.9 x 10(5) M(-1) s(-1)), amino acids (<3.7 x 10(7)), and DNA (5.1 x 10(5)). Further, these values are similar to those (1.15 x 10(8)-2.06 x 10(8) M(-1) s(-1)) of alpha- and gamma-tocopherol, ubiquinol-10, and gamma-tocopherol hydroquinone (plastoquinol model). The result suggests that catechins may contribute to the protection of oxidative damage in biological systems, by quenching (1)O(2).

Catechin↗
PubMed2006

Reduction of disinfection by-products precursors by nanofiltration process.

This research is dedicated to determine the rejection ratios of disinfection by-products (DBPs) precursors including resorcinol, phloroglucinol, 3-hydroxybenzoic acid, and tannic acid solution in the presence of calcium by nanofiltration with NF70 membrane. The rejections of these model compounds also were studied at various compositions of a feed solution by changing pH and concentrations of model compounds. It was found that the model compound rejection and membrane permeability increase with pH due to the conformational transformation of ionizable molecules and electric interaction between the model compounds and NF70 membrane. The interactions of model compounds with calcium have no significant effect on model compounds retentions. Because of the complexation of calcium with model compounds, calcium rejection rises with the presence of model compounds and with an increase of pH.

Calcium↗
PubMed2006

Removal of small trihalomethane precursors from aqueous solution by nanofiltration.

The removal of small trihalomethane precursors (THMPs) from aqueous solution by two commercial nanofiltration membranes (NF70 and NF270) was investigated. Resorcinol, phloroglucinol, and 3-hydroxybenzoic acid were selected as model compounds of small THMPs, while tannic acid was chosen as a medium molecular disinfection by-product (DBP) precursor for comparison. The performance of nanofiltration membranes were evaluated by introducing polyethylene glycol (PEG) solutions and uncharged saccharides to estimate molecular weight cut-off (MWCO) and membrane pore radii, respectively. The streaming potential was measured to estimate the membrane surface charge at different pH values, which reveals that the NF270 membrane is more pH-sensitive than the NF70 membrane. The rejections of the above selected THMPs were assessed under various pH values, and the removal efficiencies of THMPs for both membranes at high pH values are reasonably well. Charge exclusion is the prevailing mechanism for the selected small model compounds retended by the negatively charged nanofiltration membranes, while size exclusion and adsorption are controlled mechanisms but not sufficient for the rejection of unionized small organic molecules. In general, the NF270 membrane exhibits the superior permeation rate value, which takes an advantage over the NF70 membrane from the aspect of energy conservation.

Filtration↗
PubMed2004

Redox-dependent changes in RsrA, an anti-sigma factor in Streptomyces coelicolor: zinc release and disulfide bond formation.

sigmaR is a sigma factor for transcribing genes to defend cells against oxidative stresses in the antibiotic-producing bacterium Streptomyces coelicolor. The availability of sigmaR is regulated by RsrA, an anti-sigma factor, whose sigmaR-binding activity is regulated by redox changes in the environment, via thiol-disulfide exchange. We found that reduced RsrA contains zinc in a stoichiometric amount, whereas oxidized form has very little: 1 mol of zinc per mol of RsrA was released upon oxidation as monitored by a chromogenic Zn-chelator, 4-(2-pyridylazo)-resorcinol (PAR). Measurement of zinc bound in several RsrA mutants of various cysteine and histidine substitutions suggested that C3, H7, C41, and C44 serve as zinc-binding sites. The zinc-binding and sigmaR-binding activities of mutant proteins did not coincide, suggesting that zinc might not be absolutely required for the anti-sigma activity of RsrA. Zn-free apo-RsrA bound sigmaR and inhibited sigmaR-dependent transcription in vitro. Compared with Zn-RsrA, the anti-transcription activity of apo-RsrA was about threefold lower and its sigmaR-binding affinity decreased by about ninefold when measured by surface plasmon resonance analysis. Apo-RsrA was more sensitive to protease, suggesting that zinc allows RsrA to maintain a more compact structure, optimized for binding sigmaR. The cysteine pairs that form disulfide bonds were determined by MALDI-TOF mass spectrometry, revealing formation of the critical disulfide bond between C11 and one of the essential cysteine residues C41 or 44, most likely C44. An improved model for the mechanism of redox-modulation of RsrA was presented.

Bacterial Proteins↗
PubMed2005

1,3-dihydroxy-5-(tridec-4',7'-dienyl)benzene: a new cytotoxic compound from Lithraea molleoides.

A dichloromethane extract from the leaves of Lithraea molleoides (Anacardiaceae), an argentine medicinal plant, showed cytotoxicity on human hepatocellular carcinoma cell line. Bioassay guided fractionation of this extract led to the isolation of a new active 5-alkyl resorcinol: 1,3-dihydroxy-5-(tridec-4',7'-dienyl)benzene. Chemical structure was established based on spectroscopic data (UV, IR, MS, 1H-NMR, 13C-NMR, COSY). This compound presented cytotoxic activity on 3 human tumoral cell lines: hepatocellular carcinoma cell line-Hep G2 (IC50 +/- SD of 68 +/- 2 microM), mucoepidermoid pulmonary carcinoma cell line-H292 (IC50 +/- SD of 63 +/- 5 microM) and mammary gland adenocarcinoma cell line -MCF7 (IC50 +/- SD of 147 +/- 5).

Anacardiaceae↗
PubMed2005

Study of charge transfer complexes of [70]fullerene with phenol and substituted phenols.

To improve the understanding of the charge transfer (CT) interaction of [70]fullerene with electron donors, interaction of [70]fullerene with a series of phenols, e.g., phenol, resorcinol and p-quinol were studied in 1,4-dioxan medium using absorption spectroscopy. An absorption band due to CT transition was observed in the visible region. The experimental CT transition energies (h nuCT) are well correlated (through Mulliken's equation) with the vertical ionisation potentials (I(D)v) of the series of phenols studied. From an analysis of this correlation degrees of charge transfer for the [70]fullerene-phenol complexes were estimated. The degrees of charge transfer in the ground state of the complexes have been found to be very low (<2%). The h nuCT values change systematically as the number and position of the -OH groups change on the aromatic ring of the phenol moiety. From the trends in the h nuCT values, the Hückel parameters (h(O) and k(C-O)) for the -OH group were obtained in a straightforward way and the values so obtained, viz., 1.91 and 1.0, respectively, are close to the ones (1.8 and 0.8) recommended by Streitwieser on the basis of other evidence. Oscillator strengths, transition dipole strengths and resonance energies of the [70]fullerene-phenol complexes were determined. Formation constants of the CT complexes were determined at four different temperatures from which enthalpies and entropies of formation of the complexes were estimated.

Electron Transport↗
PubMed2006

Simultaneous determination of cobalt and palladium in micellar media using H-point standard addition method and partial least square regression.

A simple, sensitive and selective spectrophotometric method for the simultaneous determination of Co(II) and Pd(II) using partial least square (PLS) calibration and H-point standard addition method is described. The method is based on the complex formation of Co(II) and Pd(II) with 4-(2-pyridylazo) resorcinol (PAR) in acidic media and in the presence of sodium dodecyl sulfate (SDS) as a micellizing agent. Acidic media and the presence of a micellar system improve selectivity and sensitivity, respectively. By applying PLS calibration, Co(II) and Pd(II) can be determined in the range of 0.20-2.0 and 0.40-4.0 microg ml(-1), respectively. The relative errors of prediction for the determination of Co(II) and Pd(II) in the 10 prediction samples were 1.69 and 1.72%, respectively. The results of applying H-point standard addition method show that Co(II) and Pd(II) can be determined simultaneously with concentration ratio of Co(II) to Pd(II) varying between 7:1 and 1:8 in the mixed samples. Both proposed methods (PLS and HPSAM) were applied to the determination of Co(II) and Pd(II) in several alloy solutions with satisfactory results.

Alloys↗
PubMed2000

Pericardial hood repair of cardiac rupture secondary to extended myocardial infarction.

A surgical technique for simple and safe repair of oozing-type postinfarction cardiac rupture secondary to extended myocardial infarction is described. A hood-shaped pericardium was glued with gelatin-resorcinol and formaldehyde glue to cover the extended oozing infarcted myocardium. This technique was used on 3 elderly patients with good results.

Aged↗
PubMed2000

Late complications of tissue glues in aortic surgery.

BACKGROUND: Tissue glues are used in cardiothoracic surgery as an adjunct to operative procedures where tissues are frail, as in aortic dissection, or where added hemostasis is required. This study was undertaken to review the use of tissue glue in our institution over a 5.5-year period. The aim of the study was to identify any potentially glue-related complications. METHODS: A review of tissue glue use for the period from January 1993 to September 1998 was performed and pre-, intra-, and postoperative parameters were collected. After some unusual surgical findings, of special interest was a range of pathology found at late reoperation. RESULTS: A total of 67 cases of tissue glue use were identified, with the majority of operations for type A dissection (76%). There were two intraoperative deaths. Twenty-seven of 65 patients (41%) required 29 further open chest operations; of these, 17 were for acute problems of bleeding or tamponade. Twelve patients (18%) underwent late reoperations months to years later. Nine of these patients, concentrated in two operative groups (7 patients with aortic valve resuspension and 2 patients who had undergone "switch" operations for transposition of great vessels), displayed complications related to the application of gelatin-resorcinol-formaldehyde (GRF) tissue glue. CONCLUSIONS: Indications for tissue glues in cardiothoracic surgery must be carefully considered. We have reviewed our use of some tissue glues in acute type A aortic dissections and in pediatric cardiac patients and have discontinued the use of GRF glues because of unsatisfactory long-term complications.

Aortic Dissection↗
PubMed2001

Glue aortoplasty repair of aortic dissection after coronary angioplasty.

Aortic dissection complicating percutaneous transluminal coronary angioplasty is rare. We report the case of a 45-year-old man who after right coronary artery angioplasty with stenting, dissected that vessel to involve the aorta to the bifurcation. Surgical repair with Gelatin-Resorcinol-Formaldehyde (GRF) glue as opposed to prosthetic graft replacement of the ascending aorta was successful. The use of GRF glue is effective in the surgical treatment of aortic dissection after coronary angioplasty.

Aortic Dissection↗
PubMed2001

Role of biologic glue repair of proximal aortic dissection in the development of early and midterm redissection of the aortic root.

BACKGROUND: Redissection of the aortic root after supracommissural aortic graft replacement with reapproximation of the layers of the dissected aortic root is relatively rare. Causes and surgical treatment of this lesion remain controversial. METHODS: From January 1983 to September 2000, 130 patients had emergency operation for acute type A aortic dissection. Of them, 57 patients underwent root reconstruction using biologic glues and 4 patients (7.0%) developed redissection of the aortic root associated with moderate to severe aortic regurgitation 5 to 27 months after the initial operation. In all patients, the proximal false lumen was obliterated with infusion of gelatin-resorcinol-formaldehyde (GRF) glue or BioGlue and the aorta was reinforced with Teflon felt strip or Surgicel placed on its outside wall. RESULTS: During reoperation, the noncoronary aortic sinus was found to be redissected in all patients with the dissection extending retrogradely to the aortic annulus. This resulted in aortic regurgitation with prolapse of the noncoronary cusp because the proximal suture line dehisced. Histopathology showed disappearance of the nuclei of the medial smooth muscle cells, suggesting tissue necrosis at the site of GRF glue application. The lesions were treated successfully with full root replacement using a freestyle heterograft bioprosthesis or a composite graft prosthesis. CONCLUSIONS: The use of biologic glues for reapproximating the layers of the dissected aortic root is associated with a certain amount of risk of aortic wall necrosis. Therefore, care should be taken to ensure proper use of these glues. Full root replacement could be a preferable technique for treating redissection of the aortic root.

Adult↗
PubMed1997

Aortic valve conservation in acute type A dissection.

BACKGROUND: We consider operative survival as the primary objective in acute type A dissection and believe that virtually all native aortic valves can be conserved. We sought to answer the question: "Does glue repair improve the long-term stability of proximal aortic repair?" METHODS: We retrospectively studied 64 patients with an acute type A dissection, an ascending aortic tear, and aortic regurgitation operated on by the same surgeon between 1988 and 1996. Three had Marfan's syndrome and 2 had a bicuspid valve. The valves in all patients without Marfan's syndrome were repaired with gelatin-resorcinol-formol glue. The valve and root were reinvestigated by echocardiography. Some patients underwent nuclear magnetic resonance imaging. RESULTS: There were four hospital (6%) and three late deaths. Aortic root reoperation was required in 2 of the 60 survivors (3.3%) and operation on the distal aorta in 2. Root reoperations were required within 3 years. The remaining proximal repairs remained stable. CONCLUSIONS: The native aortic valve can be conserved in most patients, and glue repair is durable. Simple root repair is associated with a low operative mortality.

Adult↗
PubMed1999

Surgery for acute type A aortic dissection: the Hopital Foch experience (1977-1998).

BACKGROUND: In 1977, we proposed the use of gelatin-resorcinol-formol (GRF) biological glue during surgery for acute type A aortic dissection. METHODS: From January 1977 to March 1998, 204 patients (146 men and 58 women) aged from 15 to 79 years (mean 54 +/- 11) underwent emergency operation for type A aortic dissection in our institution. One hundred sixty-five patients (84%) were operated on within 48 h after the onset of symptoms. Twenty-eight patients (13.7%) had Marfan's syndrome. In 43 patients (23%), the aortic valve was replaced either independently (6, 3%) or by means of a composite graft (37, 18.1%). Because of the location of the intimal tear, aortic replacement included the transverse arch in 60 patients (29.4%). RESULTS: Hospital mortality was 21% (39 patients): 25% in patients with arch replacement and 19.4% in patients without arch replacement (ns). One hundred sixty-one patients were discharged and followed from 2 months to 21 years postoperatively (mean 85 +/- 66 months). During this interval, 25 patients (15.5%) required reoperation for a total of 33 reoperations. Seven patients (28%) died at reoperation. Upon univariate analysis, presence of Marfan's syndrome (p < 0.05) and absence of arch replacement (p < 0.02) were risk factors for reoperation. Emergency operation (p < 0.01) and thoracoabdominal replacement (p < 0.04) were risk factors for death at reoperation. The actuarial freedom from reoperation (Kaplan-Meier, confidence interval 95%) is 96.1% (90.9%-98.2%) at 1 year, 87.6% (79.8%-92.7%) at 5 years, 80.9% (70.8%-88.1%) at 10 years, and 66.4% (51.1%-78.9%) at 15 years. A total of 39 patients (24.3%) died during follow-up. The presence of Marfan's syndrome (p < 0.01), reoperation (p < 0.02), stroke (p < 0.05), and cardiac failure (p < 0.05) were risk factors for late mortality. The actuarial late survival including hospital mortality is 71.5% (64.3%-77.8%) at 1 year, 66% (58.3%-73%) at 5 years, 56.4% (47.7%-64.7%) at 10 years, and 46.3% (36.4%-56.5%) at 15 years. CONCLUSIONS: The GRF glue has proven extremely useful during emergency initial surgery for acute type A dissection, making the procedure much easier and safer. As a result of this operative improvement, the use of the GRF glue seems to have had a beneficial influence on late results, but these also depend upon the patient's basic condition.

Adolescent↗
PubMed2002

A simple method for the in situ detection of eosinophils.

A simple and rapid method for identifying eosinophils in tissue sections is described. The assay is based on the incubation of frozen tissue sections with phenol red and the detection of cellular fluorescence. A one-to-one relationship was observed between cells exhibiting fluorescence following exposure to phenol red and eosinophils as identified by histochemical detection of eosinophil peroxidase (EPO) activity. Using the phenol red assay, eosinophils were detected in various eosinophil-infiltrated tissues, including uteri of rats from day 1 of pregnancy and uteri of prepubertal estrogen-treated rats. Intensity of the fluorescing eosinophils was dependent upon phenol red concentration and duration of incubation. The phenol red method of eosinophil identification was disrupted by co-incubation with resorcinol, an EPO inhibitor, or catalase, a hydrogen peroxide scavenger. The merits of this assay are its simplicity and compatibility with other procedures, such as histochemistry, immunocytochemistry, and in situ ligand-receptor binding.

Animals↗
PubMed1997

Chemical basis of the resistance of barley seeds to pathogenic fungi.

The 5-(n)-alkylresorcinol fraction of the epicuticular waxes of Hordeum vulgare seeds appeared to be responsible for their in-born resistance to pathogenic fungi such as Aspergillus niger and Penicillium crysogenum. The antifungal properties of this fraction were evaluated qualitatively and quantitatively with a novel bioassay where the extreme lipophilicity of these compounds was taken into account. The minimum inhibitory concentration in the fungi tested ranged from 5.6 to 10 micrograms cm-2 for the alkyresorcinols. The behaviour of the different cultivars against these fungi could be predicted by measuring the natural amount of resorcinols of each variety by TLC-scanning densitometry. The ranking of cultivars thus established correlated well with the field behaviour of each cultivar, providing a useful and rapid method for predicting the behaviour against fungi of new varieties being developed.

Chromatography, Thin Layer↗
PubMed1999

Interference by plastics additives in the HPLC determination of microcystin-LR and -YR.

Plastics devices used for the field collection of water samples may contain plastics additives which will interfere with the HPLC determination of the cyanobacterial toxins microcystins. The presence of the additives resorcinol monobenzoate or 2,4-dihydroxybenzophenone can interfere with the determination of microcystin-LR. The presence of bisphenol A in plastics can interfere with the determination of microcystin-YR.

Bacterial Toxins↗
PubMed1995

Sealing ability of thermoplasticized gutta-percha fill techniques as assessed by a new method of determining apical leakage.

One hundred fifty-nine extracted single-rooted maxillary human teeth were instrumented and randomly divided into nine groups of 17 teeth each and 6 control teeth. Experimental groups were obturated with Thermafil, Obtura II, Ultrafil Regular Set gutta-percha, and Ultrafil Firm Set gutta-percha, each with or without root canal sealer. A control group was obturated using the lateral condensation technique and sealer. Teeth were immersed in a resorcinol-formaldehyde resin for 5 days at 4 degrees C, and the resin was allowed to polymerize completely for 4 days at room temperature. Teeth were then sectioned horizontally at 1.5, 2.5, and 3.5 mm from the anatomical apex, and examined under a stereomicroscope at x25 magnification. The resin filled the spaces in the gap between the canal wall and the gutta-percha and this was measured at each of the three levels. The ratio of the area of the resin to the total area of the canal was obtained as the mean leakage area. The results showed no significant difference in the mean leakage area at the same level for the different obturation materials. However, the leakage was significantly less for all materials when root canal sealer was used.

Chi-Square Distribution↗
PubMed1997

Occupational exposures and haematological abnormalities among ordnance factory workers: a case control study.

The lifetime exposures to an extensive list of chemical and other potentially toxic hazards were estimated for all available employees at an ordnance factory by questionnaire-based interview. Exposure histories of 32 (of 33) previously diagnosed as haematologically abnormal (cases) were compared with 322 (of 345) normals (controls). Among 'ordnance factory chemicals', modestly increased odds ratios were observed for men for acetic anhydride (2.8), stearic acid (2.8), and possibly for resorcinol (2.9), TNT (2.4) and hydroxy terminated polybutadene (HTPB) (2.4). Increased odds ratios were also observed in exposures not directly related to ordnance manufacture, including mineral acids, welding fumes, exhaust gases and insecticides. While, small numbers in the case group limit the statistical significance of reported odds ratios, one should be cautious about committing a type II error. These findings may partly explain the previously reported unusual prevalence of haematological abnormalities within the factory.

Acetic Anhydrides↗