Effect of pH on the stability of Pleurotus eryngii versatile peroxidase during heterologous production in Emericella nidulans

Complementary DNA (cDNA) encoding the new versatile peroxidase from the ligninolytic basidiomycete Pleurotus eryngii has been expressed in the ascomycete Emericella nidulans. In recombinant E. nidulans cultures, the pH reached values as high as 8.3, correlating with a sharp decrease in peroxidase activity. Peroxidase was rapidly inactivated at alkaline pH, but was comparatively stable at acidic pH. The peroxidase inactivation in alkaline buffer could be reversed by adding Ca(2+) and lowering the pH. However, reactivation did not result after incubating the enzyme in non-buffered E. nidulans cultures that reached pH 7.5. To optimize recombinant peroxidase production, the effect of controlling the pH in E. nidulans bioreactor cultures was studied. An extended growth period, and a significant increase in the recombinant peroxidase level (5.3-fold higher activity than in the bioreactor without pH control) was obtained when the pH was maintained at 6.8, showing that culture pH is an important parameter for recombinant peroxidase production.

Weed control and persistence of two oxyfluorfen formulations in olive groves under non tillage conditions

To obtain profitable yields in olive groves, residual preemergence herbicides are applied in October or November before the winter rains, and before the winter annual weeds germinate. Simazine, one of the herbicides most used for weed control in olive groves, has recently been banned. Oxyfluorfen is presented as a good alternative to simazine in olive fields. Experiments were carried out in 2002 and 2003 to evaluate the behaviour of two oxyfluorfen formulations, 2XL and G4F, at 480 g a.i. ha(-1) for three different soil management systems with three replications (1. bare soil; 2. bare soil and grassed buffer strips, chemically controlled and 3. bare soil and grassed buffer strips with controlled mowing; under non tillage conditions in all three cases). The most important species that survived 2XL and G4F treatments was Sagina apetala ARD. Oxyfluorfen residues were evaluated throughout 158 days after the applications. Three soil samples from each plot were collected, mixed and air dried. The herbicide extractions were made with methanol and the residues were analyzed by HPLC. We found no differences between the two formulations, but results showed that recoveries of oxyfluorfen were higher in plots with chemically controlled buffer grassed strips than in the other soil management types.

Characterization and in vitro expression patterns of an exopolygalacturonase encoding gene from Fusarium oxysporum f.sp. radicis lycopersici

AIMS

In this work, we report the isolation, characterization and expression pattern in in vitro cultures of an EXOPG encoding gene (pgx2), a novel EXOPG encoding gene of Fusarium oxysporum f.sp. radicis lycopersici, responsible for foot crown and root rot disease in tomato plants. The gene was compared with other fungal polygalacturonases (PGs) previously reported.

METHODS AND RESULTS

Partial sequences of the purified EXOPG native protein were used to design primers that amplified a genomic fragment by PCR. The amplified genomic fragment was used as a probe to screen a genomic library. One isolated clone was analysed. The complete genomic, cDNA and the deduced amino acid sequences were compared with other fungal EXOPGs and ENDOPGs. Regulation of pgx2 expression was analysed by Northern blot in in vitro cultures supplemented with different carbon sources.

CONCLUSIONS

Pgx2 was present as single copy in the haploid genome of several Fusarium species. PGX2 showed the conserved amino acid motifs typical of PGs and those reported for fungal EXOPGs. Pgx2 was regulated at transcriptional level showing similar expression pattern to other EXOPG encoding gene (pgx1) when the fungus was cultured on different carbon sources suggesting a coordinate expression of both genes. This similarity would be supported by the presence of common putative regulatory motifs in the upstream regions of both genes.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study reports the analysis of a novel EXOPG gene of the tomato pathogen F. oxysporum f.sp. radicis lycopersici, a contribution to the understanding of the role of cell-wall-degrading enzymes produced by fungi during pathogenesis.

[Detection of resistance to clarithromycin in clinical isolates of Helicobacter pylori from children and adults]

Several methods have been used to detect clarithromycin resistance. Agar dilution is now recommended by the NCCLS (susceptible to clarithromycin: MIC<=0.25 mg/l; intermediate resistance: MIC=0.5 mg/l; resistant: MIC>=1 mg/l), and the detection of mutations involved in resistance is used in many laboratories. We analyzed 36 clarithromycin-resistant strains isolated from children and 30 from adults. In vitro susceptibility to clarithromycin was determined by an agar dilution method. DNA from the isolates was extracted using the method published by Ge and Taylor. A2142G and A2143G mutations were identified by PCR-RFLP. A 1.4 Kpb of the 23S rRNA gene was amplified and digested using MboII or BsaI restriction enzymes to detect mutations. The prevalence of the A-G transition mutation at position 2143 was higher in the children (80.55%) than in the adult patients (46.66%) (p<0.05); however, the prevalence of the mutation at position 2142 was higher in adults than in children (36.66% vs. 5.55%; p<0.05). In children, a higher MIC (2-64 mg/l) was observed when the A-G mutation was detected at position 2143. However, in adult patients higher MICs were observed when the A-G mutation was detected at position 2142.

[Acceptance of generic prescribing in general practice: effect of patient education and reference prices]

AIMS

To assess patient acceptance of the substitution of brand-name drugs for generic equivalents in the context of repeat prescriptions for chronic diseases.

METHODS

A prospective multicenter study of drug use was performed. Of the 31 centers included in the study, 8 were randomized to the intervention group and 23 to the control group. For 1 year, patients in the intervention group who visited the center to collect repeat prescriptions received verbal and written information on the advantages and disadvantages of generic and brand name drugs. Data on the number of patients taking brand-name drugs for which generic equivalents were available, as well as the reasons and variables related to refusal of generic drugs (age, gender, education, primary care centre, general practitioner, type of drug and total number of repeat prescriptions) were collected. The percentage of generic drugs among the total number of drugs prescribed was calculated at 2-monthly intervals.

RESULTS

A total of 98.9% of the 4620 patients in the intervention group agreed to change to a generic formulation. The percentage of patients accepting generic drugs was significantly associated with the primary care centre, the class of drug, doctors' influence, and patient satisfaction with the drug. Generic prescriptions represented 5.9% in the intervention practices compared with 2.8% in controls. After the intervention, and before the application of reference prices, the percentages were 6.7% and 3.9%, respectively. Immediately after application of the reference prices, the percentages were 8.6% and 6.3%, respectively.

CONCLUSIONS

Direct patient education is an effective strategy in increasing the prescription of generic equivalents. General practitioners' motivation and knowledge of generic drugs influenced their use. The application of reference prices increased the use of generic equivalents.

Time course of fungal removal of lipophilic extractives from Eucalyptus globulus wood

Free and esterified sitosterol, the main lipophilic constituents of eucalypt wood extractives, have been associated with the formation of pitch deposits during manufacturing of environmentally-sound paper pulp from Eucalyptus globulus wood. These, and other lipophilic compounds, were analyzed by gas chromatography-mass spectrometry in the course of wood treatments (up to 7 weeks) with four extractive-degrading fungi in order to optimize biotechnological control of pitch deposition in eucalypt pulp (with moderate loss of wood weight). In contrast to commercialized fungi used in pitch control, which are not able to degrade sitosterol, the fungi investigated in this paper produced a rapid decline of both free and esterified sterols in wood. The degradation rate of steroid hydrocarbons and squalene was moderate, and the amount of steroid ketones (probably formed during oxidative degradation of steroids) and triglycerides increased at different stages of wood treatment. Up to 95% removal of total steroids (including free and esterified sterols, steroid ketones and steroid hydrocarbons) by fungi was obtained at the end of wood treatment under the solid-state fermentation conditions used. The most promising results from the point of view of industrial applicability, however, were obtained after 1-2 weeks of treatment with either Phlebia radiata or Poria subvermispora, which enabled 70% steroid removal with a moderate wood weight loss of 1-4%.

[Transesophageal echocardiographic diagnosis of a ruptured sinus of valsalva aneurysm with right atrium fistula]

Congenital aneurysms of the sinus of Valsalva are relatively rare, tending to be most frequent in adults. Untreated, there is a substantial risk of complication due to bacterial endocarditis and, if rupture occurs, rapid and progressive cardiac insufficiency is fatal at short term. We report the case of a 53-year-old male with a ruptured right sinus of Valsalva aneurysm, resulting in an anomalous right atrium fistula. Symptoms presented, clinical diagnosis and, above all, transesophageal echocardiography were crucial in the final diagnosis leading to an early and satisfactory surgical intervention. Catheterization and angiography were not definitive. Echocardiographic data are described and a bibliography of relevant research articles is provided.

Utility of intrarenal Doppler ultrasound in the diagnosis of renal artery stenosis

PURPOSE

To determine the utility of intrarenal Doppler parameters and waveform analysis in a hypertensive population screened for renal artery stenosis (RAS).

MATERIALS AND METHODS

Sixty five patients were studied (122 kidneys) with intrarenal Doppler sonography. Doppler waveforms of three different areas from each kidney were obtained (superior, middle and inferior level). Waveform morphology, acceleration time (AT), acceleration (Ac) and resistive index (RI) were evaluated in each kidney, comparing retrospectively the Doppler findings with the angiographic results.

RESULTS

Arteriography demonstrated 33 (27.2%) renal arteries with stenosis (18 with RAS>75%). Statistically significant differences for AT and Ac were found among the patients with RAS>75% and the other groups (P<0.01). An AT>80 ms and an Ac< or =1 m/s(2) showed a sensitivity of 89% and a specificity of 99%, for the diagnosis of RAS>75%. Better results were obtained in patients less than 50 years old (100% of sensitivity and specificity). The morphologic analysis of the Doppler waveform had poor results but the detection of a waveform grade 0 had a high specificity (98%). An additional comparison of both kidneys didn't improve the results.

CONCLUSION

Intrarenal Doppler waveform analysis using quantitative measurements (AT and Ac) is an adequate technique for the diagnosis of severe RAS in previously selected patients, especially in younger patients (<50 years).

A new versatile peroxidase from Pleurotus

Lignin peroxidase (LiP) and manganese peroxidase (MnP) have been investigated in Phanerochaete chrysosporium. A third ligninolytic peroxidase has been described in Pleurotus and Bjerkandera. Two of these versatile peroxidases (VPs) have been cloned, sequenced and characterized. They have high affinity for Mn(2+), hydroquinones and dyes, and also oxidize veratryl alcohol, dimethoxybenzene and lignin dimers. The deduced sequences show higher identity with Ph. chrysosporium LiP than MnP, but the molecular models obtained include a Mn(2+)-binding site. Concerning aromatic substrate oxidation, Pl. eryngii VP shows a putative long-range electron transfer pathway from an exposed trytophan to haem. Mutagenesis and chemical modification of this tryptophan and the acidic residues forming the Mn(2+)-binding site confirmed their role in catalysis. The existence of several substrate oxidation sites is supported further by biochemical evidence. Residue conservation in other fungal peroxidases is discussed.

The biotechnological control of pitch in paper pulp manufacturing

At present, microbial and enzymatic preparations for the control of triglyceride-containing pitch deposits during the manufacture of mechanical and sulfite paper is commercially available. However, biotechnological products for pitch control in other pulping processes, such as alkaline pulping, are under development. These products include new fungi for the removal of steroids involved in pitch deposit formation in chlorine-free pulps, to be used as a biological pretreatment of wood before pulping. Simultaneously, tailor-made enzymes are being produced using protein-engineering techniques, enabling the specific removal of pitch contaminant compounds from paper pulp.

Oxidation of hydroquinones by the versatile ligninolytic peroxidase from Pleurotus eryngii. H2O2 generation and the influence of Mn2+

Formation of H2O2 during the oxidation of three lignin-derived hydroquinones by the ligninolytic versatile peroxidase (VP), produced by the white-rot fungus Pleurotus eryngii, was investigated. VP can oxidize a wide variety of phenols, including hydroquinones, either directly in a manner similar to horseradish peroxidase (HRP), or indirectly through Mn3+ formed from Mn2+ oxidation, in a manner similar to manganese peroxidase (MnP). From several possible buffers (all pH 5), tartrate buffer was selected to study the oxidation of hydroquinones as it did not support the Mn2+-mediated activity of VP in the absence of exogenous H2O2 (unlike glyoxylate and oxalate buffers). In the absence of Mn2+, efficient hydroquinone oxidation by VP was dependent on exogenous H2O2. Under these conditions, semiquinone radicals produced by VP autoxidized to a certain extent producing superoxide anion radical (O2*-) that spontaneously dismutated to H2O2 and O2. The use of this peroxide by VP produced quinone in an amount greater than equimolar to the initial H2O2 (a quinone/H2O2 molar ratio of 1 was only observed under anaerobic conditions). In the presence of Mn2+, exogenous H2O2 was not required for complete oxidation of hydroquinone by VP. Reaction blanks lacking VP revealed H2O2 production due to a slow conversion of hydroquinone into semiquinone radicals (probably via autooxidation catalysed by trace amounts of free metal ions), followed by O2*- production through semiquinone autooxidation and O2*- reduction by Mn2+. This peroxide was used by VP to oxidize hydroquinone that was mainly carried out through Mn2+ oxidation. By comparing the activity of VP to that of MnP and HRP, it was found that the ability of VP and MnP to oxidize Mn2+ greatly increased hydroquinone oxidation efficiency.

A 9 year study of clarithromycin and metronidazole resistance in Helicobacter pylori from Spanish children

The evolution of clarithromycin, metronidazole and amoxycillin resistance in 246 Spanish Helicobacter pylori clinical isolates, obtained from paediatric patients during a 9 year period, was determined by an agar dilution technique. Clarithromycin resistance (MIC 1 mg/L) was 2.27% (IC95 0.05-12.02) in 1991-1993, 20.98% (IC95 12.72-31.46) in 1994-1996 and 28.33% (IC95 20.48-37.28) in 1997-1999 (P < 0.01). Metronidazole resistance (MIC 8 mg/L) was 7.14% (IC95 1.49-19.48) in 1991-1993, 20.25% (IC95 12.04-30.79) in 1994-1996 and 43.90% (IC95 32.95-55.30) in 1997-1999 (P < 0.01). Amoxycillin resistance was not found (all strains showed MICs < 2 mg/L).

Fungal bioturbation paths in a compact disk

We report here on bioturbation traces, with micro-dendrite textures, composed of a mixture of altered aluminum and polycarbonate, which have been developed in a common compact disk (CD), destroying information pits. Fungal hyphae proliferated in these deteriorated zones, and Geotrichum-type fungus was isolated from surface-sterilized CD fragments. The severe biodeterioration described is attributed to the slow growth of this arthroconidial fungus on the CD material in the tropical indoor environment of Belize, Central America (approximately 30 degrees C, approximately 90% humidity).

Gastrointestinal bezoars: sonographic and CT characteristics

OBJECTIVE

The purpose of this study was to assess the value of imaging studies--conventional abdominal radiographs, sonography, and CT--in the diagnosis of gastrointestinal bezoars.

METHODS AND METHODS

A review was made of the radiologic findings of 17 consecutive patients with surgically verified gastrointestinal bezoars over a period of 51 months.

RESULTS

Twelve patients had a history of previous gastric surgery. In no patient was a bezoar clinically suspected. Phytobezoars were recorded in 16 patients and a trichobezoar in only one. A total of 33 bezoars were identified at surgery. Two patients had isolated gastric bezoars, whereas 15 patients had bezoars located in the small bowel. Among the latter group, associated gastric bezoars were found in eight patients, and five patients had multiple intestinal bezoars. Abdominal radiographs revealed bezoars in three patients, sonography revealed bezoars in 15, and CT revealed bezoars in all 17. Seven patients had associated gastric bezoars revealed at CT versus only two patients with gastric bezoars revealed at sonography. CT revealed multiple intestinal bezoars in five patients whereas sonography revealed them in only two patients.

CONCLUSION

Both sonography and CT are reliable methods for diagnosing gastrointestinal bezoars. CT is more accurate, however, and exhibits a quite characteristic bezoar image; in addition, this imaging technique is able to reveal the presence of additional gastrointestinal bezoars.

Expression of Pleurotus eryngii aryl-alcohol oxidase in Aspergillus nidulans: purification and characterization of the recombinant enzyme

Aryl-alcohol oxidase (AAO) is an extracellular flavoenzyme involved in lignin biodegradation by some white-rot fungi. The enzyme catalyzes the extracellular oxidation of aromatic alcohols to the corresponding aldehydes. The electron acceptor is molecular oxygen yielding H(2)O(2) as the product. Herein we describe, for the first time, the expression of AAO from Pleurotus eryngii in the ascomycete Aspergillus nidulans. The activity of the recombinant enzyme in A. nidulans cultures is much higher than found in the extracellular fluid of P. eryngii. The recombinant enzyme showed the same molecular mass, pI and catalytic properties as that of the mature protein secreted by P. eryngii. The enzymic properties are also similar to those reported from other Pleurotus and Bjerkandera species.

[Role of Herpes simplex virus in the immune stromal keratitis]

BACKGROUND

Herpes simplex virus (HSV) infection of the cornea is a leading cause of blindness in occidental countries and a common recurrent manifestation of it is the immune stromal keratitis (ISK). However, it is not known whether active viral replication occurs during the acute phase of the disease, because isolation of the virus by conventional culture techniques has not been accomplished.

AIM

To establish the presence of HSV in patients with ISK.

MATERIAL AND METHODS

Fourteen corneal swabbing samples, from active diseased eyes of patients with clinical diagnosis of ISK, were submitted to Herpchek and PCR for the identification of HSV antigens and genome.

RESULTS

All ISK samples were negative by both techniques.

CONCLUSIONS

It was not possible to identify HSV antigens nor their genome by the methodology used. It is likely that, they can't be detected in corneal superficial layers or probably there is no viral replication at this stage of the disease, so antiviral therapy should be reconsidered.

Immunolocalization of a novel cholesteryl ester hydrolase in the endoplasmic reticulum of murine and human hepatocytes

We have recently purified a cholesteryl ester hydrolase (CEH) from rat liver microsomes. Antibodies raised against the purified protein specifically reacted with a 106-kd protein and neutralized 90% of the CEH activity of rat liver microsomes (J Lipid Res 1999;40:715-725). In this work we have used the anti-CEH antibody to study both the subcellular distribution of the protein in hepatocytes as well as its tissue-specific expression in rat. Western blotting of subcellular fractions obtained from isolated rat hepatocytes revealed that the immunoreactive 106-kd CEH was exclusively localized in microsomes. The antibody also recognized a 106-kd protein in microsomes from mouse and human liver but not from rat nonparenchymal liver cells. Confocal microscopy of HepG2 cells revealed that CEH immunoreactive material colocalized with calnexin, a marker of the endoplasmic reticulum. Furthermore, high-resolution immunoelectron microscopy of rat liver thin sections exclusively localized the CEH immunoreactivity to the endoplasmic reticulum of the hepatocyte. No CEH immunoreactivity was observed in microsomes derived from adrenal glands, ovaries, testis, pancreas, intestine, white adipose tissue, mammary gland, lung, spleen, brain, aorta, and macrophages. We report a CEH localized to the endoplasmic reticulum, erCEH, in the mammalian hepatocyte. The subcellular localization and tissue-restricted pattern of expression of erCEH suggests that it might have unique functions in liver cholesterol metabolism.

Electroanalytical determination of cadmium and lead in deciduous teeth after microwave oven digestion

A method using differential pulse anodic stripping voltammetry after microwave oven digestion was developed for the simultaneous determination of Cd(II) and Pb(II) in the deciduous teeth of children. Each tooth was weighed; deposited in a 120 mL capped Teflon vessel with 5 mL 65% nitric acid, Suprapur analytical grade; and digested in a 2-step microwave oven for 15 min. The detection limits for Cd(II) and Pb(II) in the final solution were 0.078 and 0.323 microg/L, and the quantitation limits 0.394 and 1.613 microg/L, respectively, with a linearity range of 2 microg/L for Cd(II) and 23.3 microg/L for Pb(II). The sensitivity was 2.51 nA/microg-L and 1.37 nA/microg-L, for Cd(II) and Pb(II). The main advantages of this technique are a complete and satisfactory dissolution of the tooth material with the proposed microwave oven digestion procedure, without sample pretreatments, such as drying, ashing, or powdering. The voltammetric procedure proved to be well designed because of significant goodness of fit to a linear model, and the accuracy of the method was established as compared with standard reference material. The methodology has enabled us to study Cd(II) and Pb(II) in 371 deciduous teeth from school children in Cartagena, Spain.

Short- and long-term effects of atorvastatin, lovastatin and simvastatin on the cellular metabolism of cholesteryl esters and VLDL secretion in rat hepatocytes

The short- and long-term in vitro effects of the hydroxymethylglutaryl-CoA reductase inhibitor atorvastatin, compared with lovastatin and simvastatin on VLDL secretion, and on the formation and the neutral and acid lysosomal hydrolysis of cholesteryl esters was investigated in rat liver hepatocytes maintained in suspension (2 or 4 h) or cultured in monolayers (24 h). All statins time-dependently reduced [14C]oleate incorporation into cholesteryl esters, but when exogenous cholesterol was added only atorvastatin caused an immediate transient decrease in hepatocyte ACAT activity. Activity of the lysosomal, microsomal and cytosolic CEH isoforms was unaffected by the hepatocyte treatments. Statins reduced free and esterified cholesterol mass in hepatocyte microsomes after 2 h, and this was followed by a modest decline in VLDL cholesteryl esters, whilst secretion of VLDL apoB and triglycerides was unaltered. However, after 24 h of treatment, statins caused generalized 20-40% decreases in the secretion of VLDL apoB, cholesterol and triglycerides, with the reduction in apoB48 secretion being significantly superior to that caused in apoB100. The mean diameter of secreted VLDL was not modified by either duration or drug treatment. Additional studies with subcellular fractions demonstrated that statins have a direct selective effect on the enzymes governing the cholesterol-cholesteryl ester cycle, with the exception of the microsomal CEH. Atorvastatin, lovastatin and simvastatin inhibited ACAT activity in microsomes by 50% at doses of 250, 100 and 50 microM, respectively. The cytosolic CEH elicited a biphasic profile of activity with activations up to 100 microM statin and inhibitions above 250 microM, and the lysosomal CEH was only inhibited by atorvastatin at a dose of 100 microM or more. We conclude that a prolonged, but not a short, limited availability of hepatocyte cholesterol derived from the endogenous synthesis reduces VLDL secretion, and that reactivity of statins at the cellular level are more similar than reactivity at the subcellular level as regards the cholesterol-cholesteryl ester cycle.

Production of hydroxyl radical by the synergistic action of fungal laccase and aryl alcohol oxidase

A mechanism for the production of hydroxyl radical (*OH) during the oxidation of hydroquinones by laccase, the ligninolytic enzyme most widely distributed among white-rot fungi, has been demonstrated. Production of Fenton reagent (H2O2 and ferrous ion), leading to *OH formation, was found in reaction mixtures containing Pleurotus eryngii laccase, lignin-derived hydroquinones, and chelated ferric ion. The semiquinones produced by laccase reduced both ferric to ferrous ion and oxygen to superoxide anion radical (O2*-). Dismutation of the latter provided the H2O2 for *OH generation. Although O2*- could also contribute to ferric ion reduction, semiquinone radicals were the main agents accomplishing the reaction. Due to the low extent of semiquinone autoxidation, H2O2 was the limiting reagent in Fenton reaction. The addition of aryl alcohol oxidase and 4-methoxybenzyl alcohol (the natural H2O2-producing system of P. eryngii) to the laccase reaction greatly increased *OH generation, demonstrating the synergistic action of both enzymes in the process.