A silkworm larvae plasma test for detecting peptidoglycan in cerebrospinal fluid is useful for the diagnosis of bacterial meningitis

The silkworm larvae plasma (SLP) test has been established based on a cascade reaction triggered by either peptidoglycan or (1, 3)-beta-D-glucan to produce melanin. We applied this test to the diagnosis of bacterial meningitis. Cerebrospinal fluid (CSF) obtained from patients with bacterial meningitis due to gram-positive bacteria, gram-negative bacteria, or fungi, showed positive reactions to the test. In contrast, CSF from patients with viral meningitis or noninfectious illnesses gave negative reactions. Therefore, this test seems to be useful for diagnosis of bacterial and fungal meningitis. When this test was used together with two types of limulus tests, an endotoxin-specific test, and a conventional test, meningitis was further characterized as gram-positive, gram-negative or fungal meningitis. The SLP test requires a computerized instrument for quantitative colorimetric measurement. A qualitative alternative of this test also can be accomplished by visually observing the darkening color. Thus, this method can be applied for simple and rapid diagnosis of meningitis.     

Sensitive method for the quantitative determination of proguanil and its metabolites in rat blood and plasma by liquid chromatography-mass spectrometry

A sensitive, simple and fast liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method for the determination of proguanil (PG) and its metabolites, cycloguanil (CG) and 1-(4-chlorophenyl)biguanide (4CPB), was developed and validated over a concentration range of 1-2000 ng/mL using only 50 microL of blood or plasma. After a simple solvent precipitation procedure, the supernatant was analysed directly by HPLC-MS/MS. Separation was achieved using an ethyl-linked phenyl reverse phase column with polar endcapping with an acetonitrile-water-formic acid gradient. Mass spectrometry was performed using a triple quadrupole mass spectrometer operating in positive electrospray ionization mode. The elution of PG (254.07-->169.99), CG (252.12-->195.02) and 4CPB (212.06-->153.06) was monitored using selected reaction monitoring. The three compounds and the internal standard (chloroproguanil) were well separated by HPLC and no interfering peaks were detected at the usual concentrations found in blood and plasma. The limit of quantification of PG and CG was 1 ng/mL and 5 ng/mL for 4CPB in rat blood and plasma. The extraction efficiency of PG, CG and 4CPB from rat blood and plasma was higher than 73%. The intra- and inter-assay variability of PG, CG and 4CPB were within 12% and the accuracy within +/-5%. This new assay offers higher sensitivity and a much shorter run time over earlier methods.     

Determination of 1-methoxy-2-propanol and its metabolite 1,2-propanediol in rat and mouse plasma by gas chromatography

A method utilizing capillary GC and flame ionization detection was developed for the simultaneous determination of 1-methoxy-2-propanol (propylene glycol monomethyl ether; PGME) and its metabolite 1,2-propanediol (propylene glycol; PG) in rat and mouse plasma. The calibration graphs for rat and mouse plasma were linear with correlation coefficients at>0.997 over the range 2–700 μg/ml. The limit of quantification was ca. 2 μg/ml (2 ng on-column) for both compounds in plasma of each species. The ranges of the precision and accuracy for PGME were 2.8–8.8% and 3.2–13%, respectively, and for PG were 11–26% and 10–25%, respectively. The recovery of PGME from rat and mouse plasma was ca. 73% and for PG it was ca. 65 and 31% from rat and mouse plasma, respectively. The method was used to study the oral absorption and metabolism of PGME in mice. PGME was readily absorbed and metabolized to PG following oral gavage administration at 90 mg/kg. The maximum concentrations of PGME and PG in plasma were attained at 20 and 30 min following dosing, respectively.     

A novel diagnostic method for human immunodeficiency virus type-1 in plasma by near-infrared spectroscopy

Presently, the diagnosis of virus infections is based mainly on serological assays. Although polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) have been increasingly used for the diagnosis of such viral infections, the risk of transfusion-transmitted blood-borne viruses remains. Furthermore, PCR and ELISA are expensive and time-consuming, and sometimes cause falsepositive or false-negative results. Therefore, a rapid, accurate and cost-effective diagnostic procedure is needed. We subjected plasma from individuals infected with human immunodeficiency virus type-1 (HIV-1), the causative agent of acquired immune deficiency syndrome (AIDS), as well as plasma from uninfected individuals as a control to near-infrared (NIR) spectroscopy, which may provide a rapid diagnostic method for HIV-1 infection without using any reagent. NIR spectra in the 600-1,000 nm region for plasma from pre-serologically HIV-1-infected individuals and healthy donors were subjected to partial least squares (PLS) regression analysis and leave-out cross-validation to develop a multivariate model to estimate the concentration of HIV-1. Simultaneously, the same plasma samples were examined for HIV-1 p24 by ELISA. The results obtained by the NIR spectroscopy model for HIV-1 yielded a good correlation with those obtained by the reference method (HIV-1 p24 ELISA). These results suggest that NIR spectroscopy using plasma could provide a rapid, accurate, cost-effective tool for large-scale diagnosis of HIV-1 infection.     

Determination of cycloserine in human plasma by high-performance liquid chromatography with fluorescence detection,using derivatization with p-benzoquinone

A new method for determining cycloserine in plasma samples is described. This method is based on the derivatization of cycloserine with p-benzoquinone, a reaction that takes place at the same time as the process of plasma deproteinization due to the presence of ethanol as solvent in the solution of the derivatization reagent. Four derivatives are obtained from this reaction. The main derivative is well correlated with the cycloserine concentration. The ratio between the volumes of the plasma sample and the reagent solution is 1:2 for a p-benzoquinone concentration of 1000 μg/mL. Elution from a C₁₈ column was isocratic, using a mobile phase containing (v/v) 85% aqueous 0.1% formic acid solution, and 15% (v/v) of a mixture of methanol and acetonitrile (1:1), with a flow-rate of 1 mL/min, at 25°C. Determinations by fluorescence detection were achieved with excitation at 381 nm and emission at 450 nm, with a detection limit of 10 ng/mL for an injection volume of 5 μL. This method was validated and applied to the determination of cycloserine in blood plasma samples of several healthy volunteers.     

Antibacterial activity of plasma from crocodile (Crocodylus siamensis) against pathogenic bacteria

ABSTRACT: BACKGROUND: The Siamese crocodile (Crocodylus siamensis) is a critically endangered species of freshwater crocodiles. Crocodilians live with opportunistic bacterial infection but normally suffer no adverse effects. They are not totally immune to microbial infection, but their resistance thereto is remarkably effective. In this study, crude and purified plasma extracted from the Siamese crocodile were examined for antibacterial activity against clinically isolated, human pathogenic bacterial strains and the related reference strains. METHODS: Crude plasma was prepared from whole blood of the Siamese crocodile by differential sedimentation. The crude plasma was examined for antibacterial activity by the liquid growth inhibition assay. The scanning electron microscopy was performed to confirm the effect of crude crocodile plasma on the cells of Salmonella typhi ATCC 11778. Effect of crude crocodile plasma on cell viability was tested by MTT assay. In addition, the plasma was purified by anion exchange column chromatography with DEAE-Toyopearl 650M and the purified plasma was tested for antibacterial activity. RESULTS: Crude plasma was prepared from whole blood of the Siamese crocodile and exhibited substantial antibacterial activities of more than 40% growth inhibition against the six reference strains of Staphylococcus aureus, Salmonella typhi, Escherichia coli, Vibrio cholerae, Pseudomonas aeruginosa, and Staphylococcus epidermidis, and the four clinical isolates of Staphylococcus epidermidis, Pseudomonas aeruginosa, Salmonella typhi, and Vibrio cholerae. Especially, more than 80% growth inhibition was found in the reference strains of Salmonella typhi, Vibrio cholerae, and Staphylococcus epidermidis and in the clinical isolates of Salmonella typhi and Vibrio cholerae. The effect of the crude plasma on bacterial cells of Salmonella typhi, a certain antibacterial material probably penetrates progressively into the cytoplasmic space, perturbing and damaging bacterial membranes. The effect of the crude plasma was not toxic by the yellow tetrazolium bromide (MTT) assay using a macrophage-like cell, RAW 264.7. The pooled four fractions, designated as fractions D1-D4, were obtained by column chromatography, and only fraction D1 showed growth inhibition in the reference strains and the clinical, human pathogenic isolates. CONCLUSIONS: The crude and purified plasma from the Siamese crocodile significantly showed antibacterial activity against pathogenic bacteria and reference strains by damage cell membrane of target bacterial cells. From the MTT assay, the Siamese crocodile plasma was not cytotoxic to the cells.     

Purification of erythropoietin from human plasma samples using an immunoaffinity well plate

A method is described to isolate human erythropoietin (hEPO) from plasma using an EPO-specific immunoaffinity micro well plate (IAP). The operating conditions of the method (binding, blocking and elution) were optimised to avoid isoform discrimination and cross-contamination with other glycoproteins. The overall hEPO recovery was ca. 56% and significant clean-up for plasmatic hEPO was achieved. Polyvinylpyrrolidone (PVP) was used as a blocking reagent and elution took place at pH 11.0. Under these conditions all isoforms from recombinant human EPOs (rhEPOs) and analogues were uniformly recovered guaranteeing lack of discrimination. The resulting procedure allowed isolating erythropoietin from plasma in conditions amenable to hEPO analysis by other techniques such as SDS-PAGE or IEF. Moreover, avoiding contamination with other glycosylated material allowed the identification in human plasma samples of the non-human N-glycolyl-neuraminic acid (Neu5Gc) using HPLC-FLD. Neu5Gc is present as 1–2% of the sialic acid content in rhEPO so this approach could be used to unequivocally detect abuse of rhEPOs or analogues as part of the doping control.     

Stereoselective RP-HPLC determination of esmolol enantiomers in human plasma after pre-column derivatization

A stereoselective reversed-phase HPLC assay to determine S-(-) and R-(+) enantiomers of esmolol in human plasma was developed. The method involved liquid-liquid extraction of esmolol from human plasma, using S-(-)-propranolol as the internal standard, and employed 2,3,4,6-tetra-O-acetyl-beta-d-glucopyranosyl isothiocyanate as a pre-column chiral derivatization reagent. The derivatized products were separated on a 5-microm reversed-phase C18 column with a mixture of acetonitrile/0.02 mol/L phosphate buffer (pH 4.5) (55:45, v/v) as mobile phase. The detection of esmolol derivatives was made at lambda=224 nm with UV detector. The assay was linear from 0.035 to 12 microg/ml for each enantiomer. The analytical method afforded average recoveries of 94.8% and 95.5% for S-(-)- and R-(+)-esmolol, respectively. For each enantiomer, the limit of detection was 0.003 microg/ml and the limit of quantification for the method was 0.035 microg/ml (RSD<14%). The reproducibility of the assay was satisfactory.     

Determination of CGS 16617 and stable isotope-labeled CGS 16617, an angiotensin-converting enzyme inhibitor, in human plasma by gas chromatography/mass spectrometry

An analytical method has been developed for the simultaneous determination of a novel orally active angiotensin-converting enzyme inhibitor (CGS 16617) and a stable isotope-labeled analog. Both compounds are isolated from human plasma using an ion-exchange column, derivatized with pentafluoropropionic anhydride and pentafluoropropanol, and analyzed by gas chromatography/mass spectrometry. After splitless injection on a methyl-silicon column, the compound is detected using negative ion chemical ionization with nitrous oxide as a reagent gas. CGS 16617 labeled with four deuteriums and two 13C is used as an internal standard. The accuracy and precision of the method, expressed as the overall mean +/- SD recovery obtained from two sets of 36 quality-control samples used during a clinical study (concentration range 0.2-100 ng ml-1 plasma), was 96.1 +/- 16.2% for unlabeled drug and 97.6 +/- 14.4% for the D4-labeled drug (concentration range 0.2-100 ng ml-1 plasma). The limit of quantification using 1 ml plasma is 0.2 ng ml-1 for both labeled and unlabeled drug.     

Immunoregulatory role of intestinal surfactant-like particles during Salmonella typhimurium infection

Surfactants like particles (SLP) are secreted by Intestinal epithelium. These particles have the ability to lower surface tension of intestinal epithelial cells and contain small amounts of surfactant specific proteins A, B, and D. In the intestinal lumen they are known to function as lubricants and/or as a vehicle to deliver digestive enzymes to the luminal fluid. These particles have been found to have the ability in binding of uropathogenic E.coli. But their immunological function is not known. The present study was designed to assess the role of the SLP in the regulation of immune response during Salmonella (S) typhimurium infection using a rat an enteric model. The animals were divided in four different groups including control (PBS), rats fed fat diet (corn oil), rats fed fat diet followed with S. typhimurium infection and rats with S. typhimurium infection alone. The Peyer's patches (PP), intraepithelial (IE) and lamina propria (LP) mononuclear cells were isolated from the above-mentioned groups. These mononuclear cells were then incubated in presence of S. typhimurium lysate alone, SLP alone and S. typhimurium lysate and SLP together. T cell markers CD4 and CD8, cytokines mainly pro-inflammatory ones including IFN-gamma, TNF-alpha, IL-12 etc were studied under such conditions. In addition histological studies were also carried out under these conditions. We report in this study that SLP plays an important role in modulating the cytokine level during infection. The pro-inflammatory cytokines were found significantly reduced in SLP induced diet along with the infection group compared to the infection group alone. Histopathological studies revealed the breakdown of duodenal villi after infection while only broadening of villi was observed in rats given corn oil induced SLP along with infection. These results suggested an important immuno-modulatory role for SLP during Salmonella infection.     

Acute prostaglandin reduction with indomethacin and chronic prostaglandin reduction with an essential fatty acid deficient diet both decrease plasma flow to the renal papilla in the rat

Renal distribution of prostaglandin synthetase is mainly medullary, whereas the major degrading enzyme, prostaglandin dehydrogenase is primarily cortical. This suggests that prostaglandins (PG) released from the renal medulla could affect the medullary blood vessels. In two different experiments we studied the role of PG in the regulation of renal papillary plasma flow in the rat. First study: PG synthesis were stimulated in 34 adult Sprague-Dawley rats by bleeding from the femoral artery 1% of the body weight over a period of 10 minutes. Following this, indomethacin (a PG inhibitor, 10 mg/kg i.v.) was given slowly and then renal papillary plasma flow was measured 25 minutes after the end of infusion. In 17 indomethacin rats the renal papillary plasma flow averaged 18.8 ml/100 g/minute, whereas it averaged 23.0 in 17 non-indomethacin rats given diluent, an 18% reduction (p less than .025). Second study: Male Sprague-Dawley rats were made prostaglandin deficient by fasting rats for one week, followed by 10% dextrose fluid for one week and subsequent institution of an essential fatty acid (EFA) deficient diet for two weeks. With urinary PG excretion in prostaglandin deficient rats 28 ng/24 hours compared to 149 ng in control rats, they could be considered as prostaglandin deficient. When renal papillary plasma flow was measured, the 16 prostaglandin deficient rats had a 16% lower papillary plasma flow than 16 control rats, 21.6 vs 25.6 (p less than .005). These results clearly demonstrate that PG inhibition in rats decreases plasma flow to the papilla, strongly suggesting that PG are vasodilators for the vessels supplying the renal papilla.     

Quantitative measurement of propofol and in main glucuroconjugate metabolites in human plasma using solid phase extraction-liquid chromatography-tandem mass spectrometry

A high-performance liquid chromatographic method coupled with tandem mass spectrometry detection has been developed for the determination of propofol and its main glucuroconjugate metabolites (propofol-glucuronide (PG), 1-quinol-glucuronide (1-QG) and 4-quinol-glucuronide (4-QG) in human plasma. All compounds were extracted with a single solid phase extraction procedure using Max Oasis cartridges. Propofol and thymol (internal standard) were analyzed using a C8 reversed-phase column with a mobile phase consisting of methanol-water (75:25, v/v) containing 0.025% NH(4)OH. Chromatography of glucuroconjugate metabolites and phenyl-beta-d-glucuronide (internal standard) was performed using a hydrophilic interaction liquid chromatography (HILIC) and a mixture of acetonitrile/water/ammonium acetate buffer (100 mM, pH 5, 87/1/12, v/v/v). Both chromatographic separations were achieved in isocratic mode allowing a rapid analysis without re-equilibration of the phase. The method is specific and sensitive with a range of 10-1500 ng mL(-1) for propofol and 1-QG, 20-3000 ng mL(-1) for PG and 25-3750 ng mL(-1) for 4-QG. The regression curves were linear for all compounds. The method is accurate and precise with intra-assay and inter-assay precision <8% and bias < or =6% for all compounds. This assay has allowed the successful measurement of propofol and its main glucuroconjugate metabolites in human plasma from 24 patients undergoing anaesthesia for elective partial hepatectomy surgery.     

Quantitative measurement of plasma free metanephrines by ion-pairing solid phase extraction and liquid chromatography-tandem mass spectrometry with porous graphitic carbon column

Plasma free metanephrine and normetanephrine are the best biomarkers for diagnosing pheochromocytoma. In the past few years, liquid chromatography-tandem mass spectrometry has become the preferred technology to measure plasma metanephrine and normetanephrine because of its high sensitivity and specificity, as well as fast and simple sample preparation. In this study, we report a liquid chromatography-tandem mass spectrometry method for measuring plasma metanephrine and normetanephrine. A solid phase extraction method using ion-pairing reagent and C18 stationary phase was used for sample preparation. We tested a porous graphitic carbon column and a HILIC column for chromatographic separation, and the former one showed better resolution with no interference from plasma matrix. This method was linear from 7.2-486.8 pg/mL for metanephrine and 18.0-989.1 pg/mL for normetanephrine with an accuracy of 92.2-111.8% and 92.1-115.0%, respectively. Inter-assay and intra-assay CV for metanephrine and normetanephrine at two different concentration levels ranged from 2.0% to 10.9%. In conclusion, this liquid chromatography-tandem mass spectrometry method using ion-pairing solid phase extraction and porous graphitic column was simple and efficient for measuring plasma metanephrines.     

High-performance liquid chromatography determination of ketone bodies in human plasma by precolumn derivatization with p-nitrobenzene diazonium fluoroborate

We developed and validated a sensitive and convenient high-performance liquid chromatography (HPLC) method for the specific determination of ketone bodies (acetoacetate and d-3-hydroxybutyrate) in human plasma. p-Nitrobenzene diazonium fluoroborate (diazo reagent) was used as a precolumn derivatization agent, and 3-(2-hydroxyphenyl) propionic acid was used as an internal standard. After the reaction, excess diazo reagent and plasma proteins were removed by passing through a solid-phase cartridge (C₁₈). The derivatives retained on the cartridge were eluted with methanol, introduced into the HPLC system, and then detected with UV at 380 nm. A calibration curve for acetoacetate standard solution with a 20-μl injection volume showed good linearity in the range of 1 to 400 μM with a 0.9997 correlation coefficient. For the determination of d-3-hydroxybutyrate, it was converted to acetoacetate before reaction with the diazo reagent by an enzymatic coupling method using d-3-hydroxybutyrate dehydrogenase and lactate dehydrogenase. A calibration curve for d-3-hydroxybutyrate standard solution also showed good linearity in the range of 1.5 to 2000 μM with a 0.9988 correlation coefficient. Analytical recoveries of acetoacetate and d-3-hydroxybutyrate in human plasma were satisfactory. The method was successfully applied to samples from diabetic patients, and results were consistent with those obtained using the thio-NAD enzymatic cycling method used in clinical laboratories.     

Quantification of dimethindene in plasma by gas chromatography—mass fragmentography using ammonia chemical ionization

A gas chromatographic—mass fragmentographic method using ammonia chemical ionization for the determination of dimethindene in human plasma is described. The drug was isolated from plasma by liquid—liquid extraction with hexane—2-methylbutanol. Plasma components were separated on a capillary column coated with chemically bonded methyl silicone. For detection of dimethindene, its quasi-molecular ion (M + H⁺) was mass fragmentographically monitored after chemical ionization with ammonia as reagent gas. Dimethindene was quantified using methaqualone as the internal standard: the quantification limit in plasma was 0.2 ng/ml, the within-run precision was 8.0% and the inter-run precision 5.6%. The plasma concentration—time profile was established after a single dose of 4 mg of dimethindene with an average maximum concentration of 5.5 ng/ml, detectable up to 48 h post application.     

Optimized method for determining free L-cysteine in rat plasma by high-performance liquid chromatography with the 4-aminosulfonyl-7-fluoro-2,1,3-benzoxadiazole conversion reagent

The analytical method was optimized for L-cysteine (Cys) in rat plasma with co-existing L-cystine (Cyss). We observed that more than 100% Cyss in rat plasma was converted to Cys under typical conditions for the conversion with 7-fluoro-2,1,3-benzoxadiazole-4-sulfonate (SBD-F). Another conversion reagent, 4-aminosulfonyl-7-fluoro-2,1,3-benzoxadiazole (ABD-F), was then employed, with which the reaction could be carried out at a low temperature without the use of a reducing reagent. Under the optimized conditions of 4 °C and pH 8.3, the conversion ratio of Cyss to Cys in rat plasma was as low as 5-7%. We determined the Cys concentration in plasma of the portal vein of rats that had been orally administered with Cys and Cyss by applying this method. The result indicated that Cys administration and also Cyss administration effectively increased the plasma Cys level. The method developed in this study is well suited for determining the thiol compounds in biological samples.     

Anion-exchange high-performance liquid chromatographic assay of plasma lipoproteins of rabbits, rats and mice

A fast, accurate and precise high-performance liquid chromatographic assay method has been developed for plasma lipoproteins of experimental animals, rabbits, rats and mice. The method includes complete separation of high, low and very low density lipoproteins from one another within 20 min by a DEAE–glucomannan gel using stepwise elution, and determination by postcolumn reaction with an enzymatic cholesterol reagent as the total cholesterol level. The relative standard deviation of each lipoprotein assay was highly reproducible, being less than 2.0 and 2.4% for repeatability and intermediate precision, respectively. The method was successfully applied to the assays of plasma lipoproteins in three species of normolipidemic and hyperlipidemic animals.     

大肠杆菌细胞壁肽聚糖的化学修饰及荧光标记

【目的】发展一种活细菌细胞壁荧光标记方法,为后期研究细菌肽聚糖的生物合成和代谢规律以及其与细菌感染致病的关系提供新的工具。【方法】对细菌肽聚糖的生物合成前体N-乙酰葡萄糖胺-1-磷酸(GlcNAc-1-P)进行化学修饰,设计并合成含有叠氮基的GlcNAc-1-P类似物(化合物5:Ac3GlcNAz-1-P)。将该类似物与细菌共同孵育,使其作为探针进入细菌肽聚糖天然合成途径。之后提取并酶解肽聚糖组分,用红外光谱(FTIR)和液质联用(LC/MS)检测探针是否通过代谢进入细菌肽聚糖结构中。同时用外源荧光素对代谢掺入细菌肽聚糖中的探针进行染色。在激光共聚焦显微镜下观察对活细菌的荧光标记效果。【结果】通过四步有机合成反应,以79%的总收率成功获得了化合物5。将大肠杆菌(Escherichia coli BL21)作为模式菌株与化合物5共孵育后,其肽聚糖组分的LC/MS和FTIR分析结果均显示探针可以被细菌利用并被代谢掺入到肽聚糖结构中。激光共聚焦显微镜观察结果显示,荧光素可以高效标记表面携带有生物正交探针的大肠杆菌。【结论】设计合成了一种新型探针,可用于活细菌成像,为深入研究细菌肽聚糖的生物学功能及其与细菌感染致病的关系提供了一种简便的方法。     

Particle-induced myeloperoxidase release in serially diluted whole blood quantifies the number and the phagocytic activity of blood neutrophils and opsonization capacity of plasma.

Luminol-amplified chemiluminescence (CL) from phagocytes has previously been shown to be almost completely dependent on the release of myeloperoxidase (MPO) from azurophilic granules. We measured the luminol-amplified chemiluminescence response (WBCL) by using serially diluted whole blood. In these experiments, non-opsonized and serum-opsonized zymosan (NWBCL and OWBCL, respectively) were used concurrently as phagocytosable particles. We found two whole-blood dilution ranges with clinical significance: first, <0.04% of whole blood in the reaction volume, where MPO released by the zymosan-activated leukocyte population came almost totally from neutrophils and the OWBCL response could be exploited as a measure of a neutrophil count in a given blood specimen, despite the pathophysiological state of the host. In contrast, the NWBCL response was two-fold in blood samples from bacterial infection patients compared to those of controls and patients with viral infection, suggesting the use of NWBCL for the differential diagnosis of bacterial infections from viral infections; second, 0.16-1.2% of whole blood in the reaction volume, where the opsonization capacity of plasma (OC(50)) can be determined. We also found that at whole blood content >0.04%, erythrocytes quickly start to absorb chemiluminescence light, and that at whole blood content >1.2%, plasma proteins, most probably albumin and fibrinogen, start to inhibit MPO release.     

Selective and sensitive detection of pectin lyase activity using a colorimetric test: application to the screening of microorganisms possessing pectin lyase activity

Several methods have been described for the detection and quantification of polygalacturonase (PG) and pectin lyase (PL) activities. The most frequently used tests are the Nelson method using copper(II) and an arsenomolybdate reagent to detect PG activity, and the colorimetric method using thiobarbituric acid (TBA) to detect PL activity. We observed that none of these methods are suitable to differentiate between these two enzymatic activities. Therefore, we optimized the test conditions of the TBA method. As a result, the detection of the enzymatic beta-elimination (PL activity) became sensitive and selective. A basic pretreatment at 80 degrees C for 5 min of the solution which contains the pectin fragments of the PL activity furnished aldehydes which were condensed with TBA or its derivatives. After acidification of the medium, a pink fluorescent dye was detected spectrophotochemically (lambda = 550 nm). The interference of galacturonic acid or oligomers resulting from PG activity was completely eliminated. The most sensitive reagent was N-(pyridin-2-yl)-thiobarbituric acid. The application of this method with the new reagent was extended to the screening of microorganisms possessing the PL activity. The obtained results confirm that Aspergillus niger strain and a Saccharomyces cerevisiae SCPP strain possess this activity.