Ratiometric Fluorescent Safranin-O Staining Allows the Quantification of Lignin Contents In Muro

In some specific vascular plant tissues, lignin can impregnate the entire cell wall to make it more rigid and hydrophobic. Different techniques have been developed in the past years to make possible the quantification of this polyphenolic polymer at the organ or tissue level, but difficulties of access to the cellular level remain. Here we describe an approach based on ratiometric emission measurements using safranin-O and the development of a macro adapted for the FIJI software, which makes it possible to quantify lignin in three different layers of the cell wall on images captured on a fluorescent confocal microscope.

Degradation, adsorption and leaching of phenazine-1-carboxamide in agricultural soils

Phenazines, a large group of nitrogen-containing heterocycles with promising bioactivities, can be widely used as medicines and pesticides. But phenazines also generate toxicity risks due to their non-selective DNA binding. The environmental fate of phenazines in soils is the key to assess their risks; however, hitherto, there have been very few related studies. Therefore in the present study, the degradation, adsorption and leaching behaviors of a typical natural phenazine-phenazine-1-carboxamide (PCN) in agricultural soils from three representative places in China with different physicochemical properties were, for the first time, systematically studied in laboratory simulation experiments. Our results indicated that the degradation of PCN in all the tested soils followed the first order kinetics, with half-lives ranging from 14.4 to 57.8 d under different conditions. Soil anaerobic microorganisms, organic matter content and pH conditions are important factors that regulating PCN degradation. The adsorption data of PCN were found to be well fitted using the Freundlich model, with the r² values above 0.978. Freundlich adsorption coefficient K_f of PCN ranged from 5.75 to 12.8 [(mg/kg)/(mg/L)^1/n] in soils. The retention factor R_f values ranged from 0.0833 to 0.354, which means that the mobility of PCN in the three types of soil is between immobile to moderately mobile. Our results demonstrate that PCN is easily degraded, has high adsorption affinity and low mobility in high organic matter content and clay soils, thus resulting in lower risks of contamination to groundwater systems. In contrast, it degraded slowly, has low adsorption affinity and moderately mobile in soils with low organic matter and clay content, therefore it has higher polluting potential to groundwater systems. Overall, these findings provide useful insights into the future evaluation of environmental as well as health risks of PCN.

How best to approach these acute hand infections

Antimicrobial therapy is not straightforward with the 4 infectious conditions reviewed here. Combination therapy at the start must usually be tailored once an organism is known.

Degradation of safranin by heterogeneous Fenton processes using peanut shell ash based catalyst

Today, dyes are one of the major problematic pollutants in the environment and are broadly used in several industrial sectors. In the current research work, decolorization of safranin (basic dye) from aqueous solution was investigated using iron-impregnated peanut shell ash (Fe-PSA) as a catalyst in the UV-assisted heterogeneous Fenton process (Fe-PSA/H₂O₂/UV). The effect of parameters such as H₂O₂ concentration, catalyst dose, pH, initial dye concentration, temperature, and agitation speed was studied. The maximum decolorization of safranin was achieved at optimum parametric values of reagent dose = 8 mM, catalyst dose = 0.5 g, pH = 3, initial concentration of safranin = 50 ppm, temperature = 25 °C, and agitation speed = 200 rpm. The results revealed the efficient performance of Fe-PSA as catalyst in the Fe-PSA/H₂O₂/UV process for safranin treatment.

Efficient photocatalytic removal of safarnin-O dye pollutants from water under sunlight using synthetic bentonite/polyaniline@Ni2O3 photocatalyst of enhanced properties

This study involves a synthesis of bentonite/polyaniline composite (BE/PANI) of enhanced physicochemical properties as catalyst support for Ni₂O₃ photocatalyst. The change in the structural properties, morphological features, and optical behavior was addressed utilizing several analytic techniques. The characterization results reflected considerable enhancement in the specific surface area after the integration between bentonite and polyaniline (127 m²/g) and after loading of the campsite by Ni₂O₃ forming bentonite/polyaniline@Ni₂O₃ composite (BE/PANI@Ni₂O₃) (231 m²/g). Additionally, the band gap energy was reduced to 2.41 eV and 1.61 eV for BE/PANI and BE/PANI@Ni₂O₃, respectively, as compared to that of 3.4 eV for pure Ni₂O₃. The photocatalytic removal of safranin-O dye under sunlight exposure using BE/PANI@Ni₂O₃ as catalyst revealed great enhancement in the removal percentages by 63%, 75%, and 72.35% higher than bentonite, polyaniline, and Ni₂O₃, respectively. Five milligrams per liter of safranin-O dye can be completely removed from 100 ml water using 0.05 g of the composite after 90 min. The catalyst also was applied effectively in the removal of safranin-O dye from raw water samples as a realistic application of the synthetic composite. Synthetic BE/PANI@Ni₂O₃ as photocatalyst showed very high stability and can be used seven times as photocatalytic at amazing removal percentages.

Real-time monitoring of phenazines excretion in Pseudomonas aeruginosa microbial fuel cell anode using cavity microelectrodes

Phenazines are a kind of metabolites that can mediate extracellular Pseudomonas aeruginosa (P. aeruginosa) cells in microbial fuel cells (MFCs). However, it is still not clear that whether and how the excretion profile of phenazines is affected by the operating MFC. Here, we report a real time analysis approach based on a cavity microelectrode electrochemical sensor to investigate the phenazines excretion behavior of P. aeruginosa during MFC operation. The phenazine concentration increases at first 72 h, reaches a plateau and decreases after 120 h and also shows local dependent variation. It is dependent on the MFC current generation profile but also affect by the biofilm formation. Accordingly, a mechanism about phenazines excretion in MFC anode and the phenazines mediated extracellular electron transfer of the P. aeruginosa anode is proposed. This work provides a novel strategy for self-mediated extracellular electron transfer analysis in the operating MFCs.

Genome-based discovery of a novel membrane-bound 1,6-dihydroxyphenazine prenyltransferase from a marine actinomycete

Recently, novel prenylated derivatives of 1,6-dihydroxyphenazine have been isolated from the marine sponge-associated Streptomyces sp. SpC080624SC-11. Genome sequencing of this strain now revealed a gene cluster containing all genes necessary for the synthesis of the phenazine and the isoprenoid moieties. Unexpectedly, however, the cluster did not contain a gene with similarity to previously investigated phenazine prenyltransferases, but instead a gene with modest similarity to the membrane-bound prenyltransferases of ubiquinone and menaquinone biosynthesis. Expression of this gene in E. coli and isolation of the membrane fraction proved that the encoded enzyme, Mpz10, catalyzes two successive prenylations of 1,6-dihydroxyphenazine. Mpz10 is the first example of a membrane-bound enzyme catalyzing the prenylation of a phenazine substrate, and one of few examples of membrane-bound enzymes involved in the prenylation of aromatic secondary metabolites in microorganisms.

Accumulation of the antibiotic phenazine-1-carboxylic acid in the rhizosphere of dryland cereals

Natural antibiotics are thought to function in the defense, fitness, competitiveness, biocontrol activity, communication, and gene regulation of microorganisms. However, the scale and quantitative aspects of antibiotic production in natural settings are poorly understood. We addressed these fundamental questions by assessing the geographic distribution of indigenous phenazine-producing (Phz(+)) Pseudomonas spp. and the accumulation of the broad-spectrum antibiotic phenazine-1-carboxylic acid (PCA) in the rhizosphere of wheat grown in the low-precipitation zone (<350 mm) of the Columbia Plateau and in adjacent, higher-precipitation areas. Plants were collected from 61 commercial wheat fields located within an area of about 22,000 km(2). Phz(+) Pseudomonas spp. were detected in all sampled fields, with mean population sizes ranging from log 3.2 to log 7.1 g(-1) (fresh weight) of roots. Linear regression analysis demonstrated a significant inverse relationship between annual precipitation and the proportion of plants colonized by Phz(+) Pseudomonas spp. (r(2) = 0.36, P = 0.0001). PCA was detected at up to nanomolar concentrations in the rhizosphere of plants from 26 of 29 fields that were selected for antibiotic quantitation. There was a direct relationship between the amount of PCA extracted from the rhizosphere and the population density of Phz(+) pseudomonads (r(2) = 0.46, P = 0.0006). This is the first demonstration of accumulation of significant quantities of a natural antibiotic across a terrestrial ecosystem. Our results strongly suggest that natural antibiotics can transiently accumulate in the plant rhizosphere in amounts sufficient not only for inter- and intraspecies signaling but also for the direct inhibition of sensitive organisms.

Synthesis of new riminophenazines with pyrimidine and pyrazine substitution at the 2-N position

New riminophenazines with pyrimidine and pyrazine substituents at the 2-position were successfully synthesized. The key step is the 2-N-arylation of riminophenazines with pyrimidine and pyrazine. The optimized reaction conditions involve the use of a Pd₂(dba)₃/DPPF/Cs₂CO₃/toluene combination.

Assay of labile estrogen o-quinones, potent carcinogenic molecular species, by high performance liquid chromatography-electrospray ionization tandem mass spectrometry with phenazine derivatization

A sensitive and selective assay method for labile estrogen o-quinones, estrone (E(1))-2,3-quinone (Q), E(1)-3,4-Q, estradiol (E(2))-2,3-Q and E(2)-3,4-Q, based on the use of phenazine (Phz) derivatization with o-phenylenediamine and high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) was described. The Phz derivatives of four estrogen o-quinones were purified by solid phase extraction and analyzed by HPLC-ESI-MS/MS. The protonated molecule was observed as a base peak for all Phz derivatives in their ESI-mass spectra (positive mode). In multiple reaction monitoring, the transition from [M+H]+ to m/z 231 was chosen for quantification. Calibration curves for the o-quinones were obtained using standard catechol estrogens after sodium metaperiodate treatment and Phz derivatization. Using this method, these four estrogen o-quinones were analyzed with the limit of quantification of 5 ng/ml in acetonitrile (MeCN)-blank matrix (1:4, v/v), respectively, on a basis of the weight of catechol estrogens. Assay accuracy and precision for four estrogen o-quinones were 89.6-113.0% and 3.1-12.6% (5, 125 and 2000 ng/ml in MeCN-blank matrix). Applications of this method enabled to determine the catalytic activities on hydroxylation and subsequent oxidation of E(1) and E(2) of Mushroom tyrosinase and rat liver microsomal fraction. It was confirmed by this method that tyrosinase exhibited 2- and 4-hydroxylation and further oxidation activities for catechols in the ring-A of estrogens. Whereas rat liver microsomal fraction possessed only 2- and 4-hydroxylation activities, and further oxidation activity for catechol estrogens was low.

Rapid quantitative analysis of phenazine-1-carboxylic acid and 2-hydroxyphenazine from fermentation culture of Pseudomonas chlororaphis GP72 by capillary zone electrophoresis

Natural phenazines in secondary metabolites of bacteria have been receiving increasing attention in recent years due to their potential usage as antibiotics. In the present study, a rapid and reliable capillary zone electrophoresis (CZE) method was developed and validated for monitoring for the first time dynamic phenazine-1-carboxylic acid (PCA) and the 2-hydroxyphenazine (2-OH-PHZ) production of Pseudomonas chlororaphis GP72 during the entire fermentation cycle. The paper begins with the optimization of separate conditions for 2-OH-PHZ and PCA together with phenazine (PHZ), which is used as internal standard. The optimized conditions are: 10mM, pH 7.3 phosphate buffer, a fused-silica capillary with a total length of 49 cm x 75 microm ID, 375 microm OD with an effective length of 40 cm, 25 kV, 13 mbar 10s pressure sample injection and 25 degrees C air-cooling. The three compounds could be separated within 2 min under optimized conditions. The validation of the newly developed study shows the linear response of 2-OH-PHZ and PCA ranging from 10 to 250 microg mL(-1) with high correlation coefficient (r=0.9997 and 0.9993, n=7), low limits of detection (0.47 and 0.38 microg mL(-1)) and quantification (1.56 and 1.28 microg mL(-1)), respectively. Good precision values for intra- and inter-day detection and acceptable individual recovery ranges for 2-OH-PHZ and PCA are indicated. The newly developed method was also validated through monitoring dynamic PCA and 2-OH-PHZ production of P. chlororaphis GP72 during an 84 h growth cycle.

A simple and selective spectrophotometric flow injection determination of trace amounts of ruthenium by catalytic oxidation of safranin-O

In this work, a simple, selective and rapid flow injection method has been developed for determination of ruthenium. The method is based on its catalytic effect on the oxidation of safranin-O by metaperiodate. The reaction was monitored spectrophotometrically by measuring safranin-O absorbance at lambdamax=521. The reagents and manifold variables, which have influences on the sensitivity, were investigated and the optimum conditions were established. The optimized conditions made it possible to determine ruthenium in the ranges of 0.4-20.0 ng/mL (DeltaA=0.2819CRu+1.1840) and 20.0-100.0 ng/mL (DeltaA=0.0984CRu+7.9391) with a detection limit of 0.095 ng/mL and a sample rate of 30+/-5 samples/h. Relative standard deviation for the five replicate measurements was less than 1.84%. The proposed method has been successfully applied for analysis of ultra trace amounts of ruthenium in real samples.

Effects of either glucose or fructose and metabolic regulators on bovine embryo development and lipid accumulation in vitro

Our objective was to determine if replacing glucose with fructose would decrease cytoplasmic lipid accumulation during culture of embryos with or without regulators of metabolism. In vitro-produced bovine zygotes were cultured 60 hr in chemically defined medium-1 (CDM-1) plus 0.5% BSA and 0.5 mM fructose or glucose in Experiment 1, and glucose in Experiment 2. In both experiments, 8-cell embryos were next cultured 135 hr in CDM-2 plus 2 mM fructose or glucose in factorial combination with five treatments: (Experiment 1: control, 10% fetal calf serum (FCS), 0.3 microM phenazine ethosulfate (PES), 30 microM dinitrophenol (DNP), and PES + DNP), and (Experiment 2: control, PES, PES + DNP, and 1 and 3 microg/ml cerulenin (C1 and C3)). Day 7.5 blastocysts were stained with Sudan Black B to quantify cytoplasmic lipid droplets as small (SD, <2 microm), medium (MD, 2-6 microm), or large (LD, >6 microm). Blastocyst rates per oocyte were 22% (Experiment 1) and 15% (Experiment 2) higher (P < 0.05) for fructose than glucose. For Experiment 1, numbers of MD were lower for PES, DNP, and PES + DNP than control and FCS (P < 0.05). LD were lower for PES and DNP than control, and higher for FCS than all other treatments (P < 0.05). For Experiment 2, MD were lower (P < 0.05) for PES, and PES + DNP than C1, C3, and control. For LD, PES was lower (P < 0.05) than control, C1, and C3, but not different from PES + DNP. The only effect of hexose on lipids was that fructose resulted in fewer MD (P < 0.01) in Experiment 2. In conclusion, fructose produced more blastocysts than glucose, and PES reduced lipid accumulation.

pH-induced changes in electronic absorption and fluorescence spectra of phenazine derivatives

The visible electronic absorption and fluorescence spectra as well as fluorescence polarization degrees of imidazo-[4,5-d]-phenazine (F1), 2-methylimidazo-[4,5-d]-phenazine (F2), 2-trifluoridemethylimidazo-[4,5-d]-phenazine (F3), 1,2,3-triazole-[4,5-d]-phenazine (F4) and their glycosides, imidazo-[4,5-d]-phenazine-N1-beta-D-ribofuranoside (F1rib), 1,2,3-triazole-[4,5-d]-phenazine-N1-beta-D-glucopyranoside (F4gl), were investigated in aqueous buffered solutions over the pH range of 0-12, where the spectral transformations were found to be reversible. The effects of protonation and deprotonation on spectral properties of these dyes were studied. We have determined the ranges of pH, where individual ionic species are predominant. In aqueous buffered solutions the fluorescence was found only for neutral species of F1, F1rib, F2, and F4gl dyes, whereas for the ionic forms of these dyes, as well as for F3 and F4 ones, the fluorescence has not been detected. The concentrational deprotonation pKa values were evaluated from experimental data. It was shown that donor-acceptor properties of the substituent group in the second position of the pentagonal ring substantially affect the values of the deprotonation constants and the character of protonation for chromophore. The substitution of a hydrogen atom in the NH-group by the sugar residue blocks the formation of the anionic species, and results in enhancement of the dye emission intensity. The steep emission dependence for F1 and F1rib over pH range of 0-7 with intensities ratio of IpH 7/IpH 1=60 allows us to propose them as possible indicator dyes in luminescence based pH sensors for investigation of processes accompanied by acidification, e.g. as gastric pH-sensors. A comparative analysis of the studied dyes has shown that F4gl is the most promising compound to be used as a fluorescent probe for investigation of molecular hybridization of nucleic acids.

[Fluorescence reaction of the system of safranine T-sodium dodecylbenzene sulfonate-protein and its application]

There is a self-polymerization equilibrium system between the cation of the fluorescent dye-safranine T and its dimer. In the presence of appropriate amounts of anionic surfactant SDBS, the above mentioned equilibrium can be adjusted by a quantitative addition of protein, thus leading to a regular change in the fluorescence intensity of the system. Based on this phenomenon, the properties of the absorption spectrum and fluorescence spectrum of the system were studied, and a new fluorescence probe for the determination of protein was established. It was found that ST was apt to dimerize in the solution added with appropriate amounts of anionic surfactant. Because of the dimerization, its fluorescence intensity decreased, whereas the addition of protein caused the dimer to be depolymerized and the system fluorescence increased. A linear relationship between the fluorescence intensities and serum albumin concentration was found in the range of 0-40 microg x mL(-1) , and the detection limit found was 0.034 microg x mL(-1). The significant features of this method were its rapidity of reaction, and high sensitivity, accuracy and selectivity. The method was applied to the determination of total proteins in real human serum, and satisfactory results were obtained.

Effects of fetal calf serum, phenazine ethosulfate and either glucose or fructose during in vitro culture of bovine embryos on embryonic development after cryopreservation

This study investigated effects of hexoses, fetal calf serum (FCS), and phenazine ethosulfate (PES) during the culture of bovine embryos on blastocyst development and survival after cryopreservation by slow freezing or vitrification. The basal, control medium was chemically defined (CDM) plus 0.5% fatty acid-free BSA. In vitro-produced bovine zygotes were cultured in CDM-1 with 0.5 mM glucose; after 60 hr, 8-cell embryos were cultured 4.5 days in CDM-2. The 8-cell embryos were randomly allocated to a 2 x 3 x 2 x 3 factorial experimental design with two energy substrates (2 mM glucose or fructose); three additives (0.3 microM PES, 10% FCS, and control); two cryopreservation methods using no animal products (conventional slow freezing or vitrification); and semen from three bulls with two replicates for each bull. A total of 1,107 blastocysts were produced. Fructose resulted in 13% more blastocysts per oocyte than glucose (37.2% vs. 32.9%), and per 8-cell embryo (51.3% vs. 45.3%; P < 0.01). No differences were found for additives (P > 0.1) control, FCS, or PES for blastocysts per oocyte or per 8-cell embryo. There was a significant interaction (P < 0.05) between additives and hexoses for blastocyst production; although trends were similar, the benefit of fructose compared to glucose was greater for controls than for FCS or PES. Culture of embryos with PES, which reduces cytoplasmic lipid content, improved cryotolerance of bovine embryos; post-cryopreservation survival of blastocysts averaged over vitrification and slow freezing (between which there was no difference) was 91.9%, 84.9%, and 60.2% of unfrozen controls (P < 0.01) for PES, control, and FCS groups, respectively.

Detection of antibiotic-related genes from bacterial biocontrol agents with polymerase chain reaction

Pseudomonas chlororaphis PA23, Pseudomonas spp. strain DF41, and Bacillus amyloliquefaciens BS6 consistently inhibit infection of canola petals by Sclerotinia sclerotiorum in both greenhouse and field experiments. Bacillus thuringiensis BS8, Bacillus cereus L, and Bacillus mycoides S have shown significant inhibition against S. sclerotiorum on plate assays. The presence of antibiotic biosynthetic or self-resistance genes in these strains was investigated with polymerase chain reaction and, in one case, Southern blotting. Thirty primers were used to amplify (i) antibiotic biosythetic genes encoding phenazine-1-carboxylic acid, 2,4-diacetylphloroglucinol, pyoluteorin, and pyrrolnitrin, and (ii) the zwittermicin A self-resistance gene. Our findings revealed that the fungal antagonist P. chlororaphis PA23 contains biosynthetic genes for phenazine-1-carboxylic acid and pyrrolnitrin. Moreover, production of these compounds was confirmed by high performance liquid chromatography. Pseudomonas spp. DF41 and B. amyloliquefaciens BS6 do not appear to harbour genes for any of the antibiotics tested. Bacillus thuringiensis BS8, B. cereus L, and B. mycoides S contain the zwittermicin A self-resistance gene. This is the first report of zmaR in B. mycoides.

The culture of articular chondrocytes in hydrogel constructs within a bioreactor enhances cell proliferation and matrix synthesis

Bovine and human articular chondrocytes were seeded in 2% alginate constructs and cultured for up to 19 days in a rotating-wall-vessel (RWV) and under static conditions. Culture within the RWV enhanced DNA levels for bovine chondrocyte-seeded constructs when compared with static conditions but did not produce enhancement for human cells. There was a significant enhancement of glycosaminoglycans and hydroxyproline synthesis for both bovine and human chondrocytes. In all cases, histological analysis revealed enhanced Safranin-O staining in the peripheral regions of the constructs compared with the central region. There was an overall increase in staining intensity after culture within the RWV compared with static conditions. Type-II collagen was produced by both bovine and human chondrocytes in the peripheral and central regions of the constructs and the staining intensity was enhanced by culture within the RWV. A capsule of flattened cells containing type-I collagen developed around the constructs maintained under static conditions when seeded with either bovine or human chondrocytes, but not when cultured within the RWV bioreactor.

Photophysical studies of some dyes in aqueous solution of triton X-100

The spectral (both absorption and fluorescence) and photoelectrochemical studies of a few selective dyes, namely, anionic erythrosin B, neutral riboflavin and cationic safranin O have been carried out in aqueous solution of triton X-100, a neutral surfactant. The results show that the ionic dyes, erythrosin B and safranin O form 1:1 electron donor-acceptor (EDA) or charge-transfer (CT) complexes with triton X-100 both in the ground and excited states, whereas neutral dye riboflavin in its excited state forms 1:1 complex with triton X-100. In these complexes, the dyes act as electron acceptors whereas triton X-100 acts as an electron donor. The fluorescence spectra of erythrosin B and safranin O in presence of triton X-100 show enhancement of fluorescence intensity with red and blue shifts respectively while riboflavin shows normal quenching of fluorescence. A good correlation has been found among photovoltage generation of the systems consisting of these dyes and triton X-100, spectral shift due to complex formation and thermodynamic properties of these complexes.

Repair of large full-thickness articular cartilage defects in the rabbit

We produced large full-thickness articular cartilage defects in 33 rabbits in order to evaluate the effect of joint distraction and autologous culture-expanded bone-marrow-derived mesenchymal cell transplantation (ACBMT) at 12 weeks. After fixing the knee on a hinged external fixator, we resected the entire surface of the tibial plateau. We studied three groups: 1) with and without joint distraction; 2) with joint distraction and collagen gel, and 3) with joint distraction and ACBMT and collagen gel.

The histological scores were significantly higher in the groups with ACBMT collagen gel (p < 0.05). The area of regenerated soft tissue was smaller in the group allowed to bear weight (p < 0.05). These findings suggest that the repair of large defects of cartilage can be enhanced by joint distraction, collagen gel and ACBMT.

Determination of myoglobin based on its enzymatic activity by stopped-flow spectrophotometry

A new method has been developed for the determination of myoglobin (Mb) based on its enzymatic activity for the oxidation of o-phenylenediamine (OPDA) with hydrogen peroxide. Stopped-flow spectrophotometry was used to study the kinetic behavior of the oxidation reaction. The catalytic activity of Mb was compared to other three kinds of catalyst. The time dependent absorbance of the reaction product, 2,3-diamimophenazine (DAPN), at a wavelength of 426 nm was recorded. The initial reaction rate obtained at 40 degrees C was found to be proportional to the concentration of Mb in the range of 1.0 x 10(-6) to 4.0 x 10(-9)mol L(-1). The detection limit of Mb was found to be 9.93 x 10(-10)mol L(-1). The relative standard deviations were within 5% for the determination of different concentrations of Mb. Excess of bovine serum albumin (BSA), Ca(II), Mg(II), Cu(II), glucose, caffeine, lactose and uric acid did not interfere.

Identification of intermediate and product from methemoglobin-catalyzed oxidation of o-phenylenediamine in two-phase aqueous-organic system

Methemoglobin (metHb) was used as a mimetic enzyme for peroxidase to catalyze the oxidation reaction of o-phenylenediamine (OPDA) with H2O2 functioning as an oxidant. A reaction intermediate was obtained in two-phase aqueous-organic system and an absorption peak at 710 nm was confirmed to be that of the intermediate in relation to OPDA. The isolated product and intermediate were characterized by UV-Vis and IR spectrophotometry and HPLC-tandem mass spectrometry. The results showed that the product is 2,3-diaminophenazine, the molecular mass of the intermediate is 212 daltons, and a conceivable structure of the intermediate is suggested. Combining the catalyzed reaction mechanism of peroxidase and our experimental results, a conceivable oxidation reaction mechanism of OPDA and H2O2 using metHb as catalyst is proposed.

NMR characterization of new 10-membered-ring macrolactones and dihydrobenzophenazine-5-one, oxidized derivatives of benzo[a]phenazines

Peroxidation of the phenazine of beta-lapachone using m-ClC6H4CO3H-CH2Cl2 furnished a macrolactone with a rigid 10-membered ring, and the corresponding N-oxide, along with a dihydrobenzophenazine-5-one. All of the new compounds were fully characterized by spectroscopic methods, with the unambiguous assignment of the hydrogens and carbon NMR signals for the N-oxide, with the aid of 2-D NMR, mainly COSY, HMQC, HSQC and HMBC. For the other two compounds some signals could not be assigned owing to their own intrinsic features.

Density functional theory study of vibrational spectra of acridine and phenazine

Density functional theory (DFT) calculations using Becke's exchange in conjunction with Lee-Yang-Parr's correlation functionals (BLYP), Becke's three-parameter hybrid DFT/HF method using Lee-Yang-Parr's correlation functionals (B3LYP) and ab initio Hartree-Fock (HF) method have been carried out to investigate the structure and vibrational spectra of acridine and phenazine. Structural parameters obtained by B3LYP/6-31G* geometry optimization are in good agreement with available experimental data. The raw BLYP non-CH stretching frequencies approximate the experimental results much better than the HF results with the mean absolute deviation about 16 cm(-1). The scaled B3LYP frequencies are more reliable than that of the BLYP and HF methods with the mean absolute deviation about 17 cm(-1). On the basis of the comparison between calculated and experimental results, assignments of fundamental vibrational modes are examined. Also the structure and vibrational frequencies are compared with those of anthracene, pyridine and benzene to study the similarities and differences.

[Determination of phenazine-1-carboxylic acid in anti-fungal agent M18 by high performance liquid chromatography]

A reversed-phase HPLC method for the determination of phenazine-1-carboxylic acid (PCA) in antifungal agent M18 is established. The mobile phase was a mixture of MeOH-5 mmol/L phosphate buffer (pH 5.0) (60:40, volume ratio). The flow rate was 1.0 mL/min, and the detection wavelength was 248 nm. The linear range and detectable limit were 50 mg/L-500 mg/L and 30 mg/L respectively. The recovery was 97.53% and RSD was 1.5%. The method of PCA extraction and detection has proven to be much faster, simpler, more sensitive, accurate and reproducible than those reported already. The assay results can be used as a very important criterion for large-scale production.

Connective tissue-type mast cell leukemia in a dog

An unusual case diagnosed as connective tissue-type mast cell leukemia with marked mastocyte infiltration into visceral organs in a seven-year-old female Curly-Coated retriever is presented. Acute circulatory collapse, emesis, diarrhea, abdominal enlargement, icterus, cyanosis, dyspnea, pulmonary edema, hepatomegary, ascites, and right ventricular enlargement were observed. Hematologic and biochemical examinations revealed mast cell leukemia, mature neutrophilia, monocytosis, thrombocytopenia, hemolytic hyperbilirubinemia, hyperhistaminemia, renal and hepatic injuries. Mast cells were distributed systemically, but predominantly in the diaphragm and liver with a large mass among the serosa of ileum, cecum and colon. Mast cells were stained intensely by both safranin and berberine sulfate.

Correlation between cervical cytologic results and Gram stain as diagnostic tests for bacterial vaginosis

OBJECTIVE

Our purpose was to determine the reliability of the Papanicolaou smear in making the diagnosis of bacterial vaginosis with the vaginal Gram stain used as the diagnostic standard.

STUDY DESIGN

We conducted a prospective, blinded, cross-sectional study of 210 consecutive patients referred to the Colposcopy Clinic for evaluation of abnormal cervical cytologic results. Each patient had a standard Papanicolaou smear and Gram stain of vaginal discharge. The sensitivity, specificity, positive predictive value, and negative predictive value of the Papanicolaou smear were determined with the Gram stain used as the standard for diagnosis of bacterial vaginosis.

RESULTS

Of the 210 patients, 80 (38.1%) had Gram stains that were positive for bacterial vaginosis and 118 (56.2%) had negative Gram stains. Twelve (5.7%) had intermediate Gram stains that were also considered negative. Of the 80 patients with positive Gram stains, 44 had cervical smears consistent with bacterial vaginosis and 36 had negative smears. Of the 130 patients with negative Gram stains, two had a positive cervical smear. Therefore, compared to the Gram stain, cervical cytologic test results had a sensitivity of 55% and a specificity of 98%. The respective positive predictive and negative predictive values were 96% and 78%.

CONCLUSION

Compared to Gram stain of vaginal secretions, the cervical Papanicolaou smear has fair sensitivity (55%) and excellent positive predictive value (96%) in diagnosing bacterial vaginosis.

Determination of serum and tissue levels of phenazines including clofazimine

A rapid and sensitive HPLC method is described for the analysis of synthetic phenazines, including clofazimine, from a variety of biological samples. Phenazines were extracted from serum, tissue and fat using a mixture of dichloromethane and sodium hydroxide. The drugs were then quantified on a reversed-phase C18 column using a mobile phase consisting of 594 ml of water, 400 ml of tetrahydrofuran, 6 ml of concentrated acetic acid and 0.471 g of hexanesulfonic acid. In this mobile phase, each phenazine tested had its own retention time. This allowed one phenazine to be used as an internal standard for the analysis of other phenazines. The method was validated for clofazimine [3-(4-chloroanilino)-10-(4-chlorophenyl)-2,10-dihydro-2-(isopro pylimino) phenazine] and B4090 [7-chloro-3-(4-chloranilino)-10-(4-chlorophenyl)-2, 10-dihydro-2-(2,2,6,6-tetramethylpiperid-4-ylimino)phenazine ] (VI) and shown to be accurate and precise across a broad concentration range from 0.01 to 50 micrograms/g (microgram/ml). Extraction was 100% for each agent across this range. This system was used to measure clofazimine and VI levels following their administration to rats. The pharmacokinetic profile of VI was different to that of clofazimine, with high tissue concentrations but lower fat levels.

Effect of lonidamine on the mitochondrial potential in situ in Ehrlich ascites tumor cells

The effect of lonidamine (LND) on the mitochondrial membrane potential, in situ, of Ehrlich ascites tumour cells was investigated by using the safranine method. LND, because of its ability to inhibit electron transport from endogenous substrates to respiratory carriers, induced a de-energization of mitochondria. Addition of glucose to rotenone-treated cells induced mitochondrial membrane potential as shown by the spectral shift similar to that which occurred upon energization of mitochondria. The build-up of membrane potential in rotenone-treated cells was due to glycolytically-generated ATP because the response to glucose was abolished by LND which inhibited the glycolysis of neoplastic cells by affecting the mitochondria bound hexokinase.

A spectrophotometric modification of a sensitive densitometric Safranin O assay for glycosaminoglycans

Recently, an assay for quantification of glycosaminoglycans has been reported based on precipitation with Safranin O (Lammi, M. and Tammi, M. (1988) Anal. Biochem. 168, 352-357). In this procedure, the precipitate which forms when the glycosaminoglycan or proteoglycan is mixed with the Safranin O is collected with a dot-blot apparatus onto a membrane filter. The intensity of the color in the dots is measured densitometrically and is proportional to the amount of glycosaminoglycan or proteoglycan in the sample. This report describes a modification of the densitometric Safranin O assay which allows its use as a spectrophotometric assay. For this, the precipitates are solubilized in cetylpyridinium chloride and the absorbance determined for the resulting solutions. As with the densitometric method, guanidinium chloride diminishes the color intensity. However, the color is stable, even after solubilization, for at least one week. The precipitates collected from as much as 10 micrograms of material can be solubilized in as little as 100 microliters of cetylpyridinium chloride, so that increased sensitivity may be obtained if the solubilized precipitate is measured in a microcuvet. Thus, solubilization with cetylpyridinium chloride allows use of the Safranin O assay for glycosaminoglycans and proteoglycans even when a densitometer is unavailable.

The mutagenic modulating effect of p-phenylenediamine on the oxidation of o- or m-phenylenediamine with hydrogen peroxide in the Salmonella test

The mutagenicity of o- and m-phenylenediamine (PD) was remarkedly enhanced by oxidation; their major mutagenic oxidation products were 2,3- and 2,7-diaminophenazine, respectively. In order to evaluate the modulation effect of p-PD on the oxidation of m- or o-PD, p-PD and mixtures of m- and p-PD (m-PD/p-PD) and o- and p-PD (o-PD/p-PD) were oxidized with hydrogen peroxide and their mutagenicity was tested in Salmonella typhimurium TA98 in the presence or absence of a mammalian metabolic activation system (S9 mix). The H2O2-oxidized m-PD/p-PD and o-PD/p-PD were potent mutagens with S9 mix, whereas H2O2-oxidized p-PD was slightly mutagenic. The major mutagenic oxidation products of m-PD/p-PD and o-PD/p-PD were identified as 2,7- and 2,3-diaminophenazine, respectively, by TLC and HPLC. 2,8-Diaminophenazine was also found as a reaction product in oxidized m-PD/p-PD, and it was weakly mutagenic. The mutagenic potency of oxidized m-PD/p-PD or o-PD/p-PD was lower than that of singly oxidized m-PD or o-PD. The yield of 2,7- and 2,3-diaminophenazine was obviously decreased with increases in p-PD, and it was concluded that the declined mutagenic potency of oxidized m-PD/p-PD or o-PD/p-PD was due to the decrease in diaminophenazines. But the formation of diaminophenazines was not completely inhibited by the addition of a 9-fold molar ratio of p-PD to m-PD or o-PD, 8.6 nmole of 2,7-diaminophenazine and 1882.4 nmole of 2,3-diaminophenazine were formed from 1 mmole of m-PD and o-PD, respectively.

Mutagenicity of commercial hair dyes and detection of 2,7-diaminophenazine

Four commercial oxidative-type hair dye formulations, A, B, C, and D, were treated with hydrogen peroxide (H2O2) to simulate normal conditions of use, and the oxidized hair dyes were tested for their mutagenicity in Salmonella typhimurium TA98 in the presence of a mammalian metabolic activation system (S9 mix). Most of them did not show obvious mutagenicity in the range of 1-25 microliters/plate and all exhibited bactericidal activity at 10 microliters/plate. In order to evaluate the mutagenicity of hair dyes both before and after H2O2 oxidation, rayon linked to a copper-phthalocyanine derivative (blue rayon) was used as an adsorbent for the elimination of interfering bactericidal compounds. Adsorbed compounds on blue rayon were eluted with ammoniacal methanol and eluents were subjected to the Ames test. The mutagenicity of the blue-rayon extracts in TA98 with S9 mix was increased by H2O2 oxidation. The blue-rayon extracts obtained from oxidized A and B were potent mutagens and reverted 334 and 999 colonies/10 microliters of original substance, respectively. In addition, 88 and 249 ng of 2,7-diaminophenazine, which was extremely mutagenic in TA98 with S9 mix, were detected in the extracts of 40 ml of the hair dye formulations A and B, respectively. The mutagenicity in oxidized hair dye formulations was successfully detected by use of blue-rayon extraction. 2,7-Diaminophenazine was only formed in the hair dye formulations containing m-phenylenediamine by H2O2 oxidation. Therefore, attention needs to be paid to the use of m-phenylenediamine as a hair dye component, not only for its own toxicity but also for that of its oxidation products.

Studies on a novel antitumor antibiotic, phenazinomycin: taxonomy, fermentation, isolation, and physicochemical and biological characteristics

A new antibiotic, phenazinomycin (C27H32N2O, MW 400), was isolated from the cultural mycelium of Streptomyces sp. WK-2057. This antibiotic possesses antibacterial activities against Gram-positive bacteria in vitro, direct cytotoxic activities against HeLa S3, P388 and P388 doxorubicin-resistant cells in vitro and antitumor activities against experimental murine tumors in vivo.

Investigation of the structural properties of dihydrophenazines which contribute to their pro-oxidative interactions with human phagocytes

Twenty-six dihydrophenazine compounds, including clofazimine, were investigated, at a fixed concentration of 1 mg/l, for their effects on spontaneous and stimulus-activated generation of superoxide by human neutrophils in vitro. The synthetic chemotactic tripeptide N-formyl-L-methionyl-L-leucyl-L phenyl-alanine (FMLP) (0.1 microM) was used as a stimulant of membrane-associated oxidative metabolism. None of the agents tested influenced basal levels of superoxide generation by neutrophils. However sixteen of these compounds, all rimino phenazines, significantly increased the production of superoxide by FMLP-activated neutrophils. These pro-oxidative, priming interactions of the rimino phenazines with neutrophils were largely dependent on the nature of the alkylimino group at position 2 on the phenazine nucleus, and to a lesser extent on halogenation. Cycloalkylimino groups were generally less potent stimulants of superoxide generation by FMLP-activated neutrophils than clofazimine, and their pro-oxidative properties were independent of mono- or dichlorination. However the halogen-free cycloalkylimino compound, B669, was an exceptionally potent pro-oxidative agent. Chlorination was promotive to pro-oxidative activity in the case of dihydrophenazines with linear or branched alkylimino substituents. The pharmaco-therapeutic mechanisms of dihydrophenazines may be related to their pro-oxidative interactions with phagocytes.

Measurement of Pseudomonas aeruginosa phenazine pigments in sputum and assessment of their contribution to sputum sol toxicity for respiratory epithelium

The phenazine pigments pyocyanin and 1-hydroxyphenazine were resolved by high-pressure liquid chromatography from the sputum sol phase from 9 of 13 patients with cystic fibrosis or bronchiectasis colonized by Pseudomonas aeruginosa. The concentrations measured were each sufficient to inhibit ciliary beating in vitro and contributed a significant proportion of sol phase toxicity for respiratory epithelium.

Revised structure for the phenazine antibiotic from Pseudomonas fluorescens 2-79 (NRRL B-15132)

A phenazine antibiotic (mp, 243 to 244 degrees C), isolated in a yield of 134 micrograms/ml from cultures of Pseudomonas fluorescens 2-79 (NRRL B-15132), was indistinguishable in all of its measured physicochemical (melting point, UV and infrared spectra, and gas chromatography-mass spectrometry data) and biological properties from synthetic phenazine-1-carboxylic acid. Gurusiddaiah et al. (S. Gurusiddaiah, D. M. Weller, A. Sarkar, and R. J. Cook, Antimicrob. Agents Chemother. 29:488-495, 1986) attributed a dimeric phenazine structure to an antibiotic with demonstrably similar properties obtained from the same bacterial strain. Direct comparison of the physicochemical properties of the authentic antibiotic obtained from D. M. Weller with synthetic phenazine-1-carboxylic acid and with the natural product from the present study established that all three samples were indistinguishable within the experimental error of each method. No evidence to support the existence of a biologically active dimeric species was obtained. Phenazine-1-carboxylic acid has a pKa of 4.24 +/- 0.01 (25 degrees C; I = 0.09), and its carboxylate anion shows no detectable antimicrobial activity compared with the active uncharged carboxylic acid species. These data suggest that phenazine-1-carboxylic acid is probably not an effective biological control agent for phytopathogens in environments with a pH greater than 7.

2,3-Diaminophenazine is the product from the horseradish peroxidase-catalyzed oxidation of o-phenylenediamine

NMR and mass spectroscopic evidence has been obtained which indicates that the product of the oxidation of o-phenylenediamine by hydrogen peroxide, uncatalyzed or catalyzed by horseradish peroxidase, is 2,3-diaminophenazine. These results settle disparate literature descriptions. The process is most likely free radical in nature starting with the abstraction of a labile amino hydrogen atom.

Biomedical applications of thermospray liquid chromatography-mass spectrometry

Thermospray liquid chromatography-mass spectrometry has been applied in the solution of a number of problems of biological and biomedical interest. These include the analysis of phenazines from the Gram negative bacterium Pseudomonas aeruginosa, steroids released by rat adrenals and eicosanoids generated by human inflammatory cells. The application of the technique to leukotrienes in blood is discussed. Isotopic labelling prior to analysis, to facilitate identification and structure elucidation is outlined with reference to the steroids.

Purification and structural analysis of pyocyanin and 1-hydroxyphenazine

Pyocyanin and related members of the phenazine family are produced by Pseudomonas aeruginosa and have been associated with events of pathophysiological importance. Pyocyanin and its base hydrolysis product 1-hydroxyphenazine were purified to homogeneity by reverse-phase high-pressure liquid chromatography. Their mass spectrometric behaviour was examined with a view to evaluating the use of high-resolution chromatography/mass spectrometry in studying phenazine-mediated effects in man. The molecular mass of naturally derived pyocyanin was determined as 210 Da by thermospray liquid chromatography/mass spectrometry and confirmed by desorption electron-impact mass spectrometry. Mass spectrometric data could not be obtained by fast-atom bombardment or desorption chemical ionisation, techniques commonly used to determine molecular mass of polar or thermally labile species. The thermal lability of underivatised pyocyanin precluded analysis by gas chromatography/mass spectrometry. In contrast to pyocyanin, mass spectrometric data were readily obtained for 1-hydroxyphenazine, using direct probe analysis as well as with gas and liquid chromatography inlet systems.

High-performance liquid chromatographic determination of free myxin and its reduction product as impurities in cuprimyxin-containing creams

A stability-indicating high-performance liquid chromatographic method was developed that can detect and quantitate low levels of the two most likely breakdown products of cuprimyxin. These degradation compounds, free myxin and its reduction product, can be determined in topical cream preparations in which cuprimyxin is formulated at the 0.5% (w/w) level. The method requires a simple two-step extraction, the addition of an internal standard, and chromatography on an amine-bonded column.

[Possibility of detecting pyocyanine in Pseudomonas aeruginosa cells]

Pyocyanin can be detected in the cells of Pseudomonas aeruginosa using UV and IR spectroscopy of disturbed complete inner reflection (DCIR). Intact cells of the parent strain liberating the pigment into the cultural broth and mutant cells lacking the ability contain pyocyanin within the cells. Occasionally, pyocyanin can be detected in the outer layers of the cells, which is more typical of the parent strain. In the freshly isolated fractions of the parent strain cellular walls, pyocyanin seems to be pesent in the bound state that has changed significantly its structural organization. In due course, the hypothetical complex pyocyanin--cellular wall decomposes to yield an "oxidized" pigment similar to that liberated into the cultural broth. the cell wall of the mutant possesses the properties of "oxidized" pyocyanin immediately after isolation of the fraction. The pigment cannot be identified in the fractions of cytoplasmic membranes; pyocyanin is present in the "oxidized" state in the fractions of cytoplasm for the cells of both types. The paper discusses the role of the permeability of cytoplasmic membranes in the transport of pyocyanin from the cytoplasm into the cellular wall of the bacterium and then into the surrounding medium.

Metabolism of diethylstilbestrol: identification of a catechol derived from dienestrol

The enzymatic oxidation of E-3,4-bis-(p-hydroxyphenyl)-hex-3-ene (diethylstilbestrol) by either mushroom tyrosinase or rat liver microsomes in the presence of NADPH and air yields a catechol. Upon further oxidation of both compounds with periodate and condensation of the resulting o-quinones with o-phenylenediamine, phenazines are produced. The phenazines derived from the products of both the plant and animal enzyme systems are identical to the product obtained by oxidation of diethylstilbestrol with potassium nitrosodisulfonate and condensation of the o-quinone produced with o-phenylenediamine. High and low resolution mass spectra of the phenazine are consistent with its derivation from a catechol having two fewer hydrogens than diethylstilbestrol.