A novel laccase from Trametes polyzona with high performance in the decolorization of textile dyes

Laccases are multicopper oxidases able to oxidize several phenolic compounds and find application in numerous industrial applications. Among laccase producers, white-rot fungi represent a valuable source of multiple isoforms and isoenzymes of these multicopper oxidases. Here we describe the identification, biochemical characterization, and application of laccase 2 from Trametes polyzona (TP-Lac2), a basidiomycete fungus emerged among others that have been screened by plate assay. This enzyme has an optimal temperature of 50 °C and in acidic conditions it is able to oxidize both phenolic and non-phenolic compounds. The ability of TP-Lac2 to decolorize textile dyes was tested in the presence of natural and synthetic mediators at 30 °C and 50 °C. Our results indicate that TP-Lac2 most efficiently decolorizes (decolorization rate > 75%) malachite green oxalate, orange G, amido black10B and bromocresol purple in the presence of acetosyringone and 2,2'-azinobis (3-ethylbenzthiazoline-6-sulfonate)-ABTS. Overall, the laccase mediator system consisting of TP-Lac2 and the natural mediator acetosyringone has potential as an environmentally friendly alternative for wastewater treatment in the textile industry.

Easy Modular Integrative fuSion-ready Expression (Easy-MISE) Toolkit for Fast Engineering of Heterologous Productions in Saccharomyces cerevisiae

Nowadays, the yeast Saccharomyces cerevisiae is the platform of choice for demonstrating the proof of concept of the production of metabolites with a complex structure. However, introducing heterologous genes and rewiring the endogenous metabolism is still not standardized enough, affecting negatively the readiness-to-market of such metabolites. We developed the Easy Modular Integrative fuSion-ready Expression (Easy-MISE) toolkit, which is a novel combination of synthetic biology tools based on a single Golden Gate multiplasmid assembly meant to further ameliorate the rational predictability and flexibility of the process of yeast engineering. Thanks to an improved cloning screening strategy, double and independent transcription units are easily assembled and subsequently integrated into previously characterized loci. Moreover, the devices can be tagged for localization. This design allows for a higher degree of modularity and increases the flexibility of the engineering strategy. We show with a case study how the developed toolkit accelerates the construction and the analysis of the intermediate and the final engineered yeast strains, leaving space to better characterize the heterologous biosynthetic pathway in the final host and, overall, to improve the fermentation performances. Different S. cerevisiae strains were built harboring different versions of the biochemical pathway toward glucobrassicin (GLB) production, an indolyl-methyl glucosinolate. In the end, we could demonstrate that in the tested conditions the best-producing strain leads to a final concentration of GLB of 9.80 ± 0.267 mg/L, a titer 10-fold higher than the best result previously reported in the literature.

Recycling industrial food wastes for lipid production by oleaginous yeasts Rhodosporidiobolus azoricus and Cutaneotrichosporon oleaginosum

BACKGROUND

Microbial lipids have been emerging as a sustainable alternative to vegetable oils and animal fat to produce biodiesel and industrial relevant chemicals. The use of wastes for microbial processes can represent a way for upgrading low value feedstock to high value products, addressing one of the main goals of circular economy, the reduction of wastes by recycling. Two oleaginous yeasts, Rhodosporidiobolus azoricus and Cutaneotrichosporon oleaginosum, were used in this study to demonstrate the feasibility of the proposed approach.

RESULTS

In this study wastes from industrial food processing, as pumpkin peels and syrup from candied fruits manufacture, were used for yeast cultivation and for lipids production. Evaluation of growth and sugar consumption revealed marked differences between the yeasts in capacity to utilize the main sugars present in the feedstock. In particular, we observed an unexpected limitation in glucose metabolism on mineral defined media by R. azoricus. Both species showed ability to grow and accumulate lipids on media exclusively composed by undiluted pumpkin peel hydrolysate, and R. azoricus was the best performing. By a two-stage process carried out in bioreactor, this species reached a biomass concentration of 45 g/L (dry weight) containing 55% of lipids, corresponding to a lipid concentration of 24 g/L, with a productivity of 0.26 g/L/h and yield of 0.24 g lipids per g of utilized sugar.

CONCLUSIONS

Wastes from industrial food processing were sufficient to completely support yeast growth and to induce lipid accumulation. This study provides strong evidence that the concept of valorisation through the production of lipids from the metabolism of nutrients present in agro-industrial wastes by oleaginous yeasts is promising for implementation of biotechnological processes in a circular economy contest.

Screening For Yeast Phytase Leads to the Identification of a New Cell-Bound and Secreted Activity in Cyberlindnera jadinii CJ2

Phytic acid is an anti-nutritional compound able to chelate proteins and ions. For this reason, the food industry is looking for a convenient method which allows its degradation. Phytases are a class of enzymes that catalyze the degradation of phytic acid and are used as additives in feed-related industrial processes. Due to their industrial importance, our goal was to identify new activities that exhibit best performances in terms of tolerance to high temperature and acidic pH. As a result of an initial screening on 21 yeast species, we focused our attention on phytases found in Cyberlindnera jadinii, Kluyveromyces marxianus, and Torulaspora delbrueckeii. In particular, C. jadinii showed the highest secreted and cell-bound activity, with optimum of temperature and pH at 50°C and 4.5, respectively. These characteristics suggest that this enzyme could be successfully used for feed as well as for food-related industrial applications.

Marine Microorganisms for Biocatalysis: Selective Hydrolysis of Nitriles with a Salt-Resistant Strain of Meyerozyma guilliermondii

A screening among marine yeasts was carried out for nitrile hydrolyzing activity. Meyerozyma guilliermondii LM2 (UBOCC-A-214008) was able to efficiently grow on benzonitrile and cyclohexanecarbonitrile (CECN) as sole nitrogen sources. A two-step one-pot method for obtaining cells of M. guilliermondii LM2 (UBOCC-A-214008) endowed with high nitrilase activity was established; the resulting whole cells converted different nitriles with high molar conversions and showed interesting enantioselectivity toward racemic substrates. Nitrilase from M. guilliermondii LM2 (UBOCC-A-214008) displayed high activity on aromatic substrates, but also arylaliphatic and aliphatic substrates were accepted. Salt-resistant M. guilliermondii LM2 (UBOCC-A-214008) was used in media with different salinity, being highly active up to 1.5 M NaCl concentration. Finally, hydrolysis of nitriles was efficiently performed using a bioprocess (yeast growth and biotransformation with resting cells) entirely carried out in seawater.

Hyper-Osmotic Stress Elicits Membrane Depolarization and Decreased Permeability in Halotolerant Marine Debaryomyces hansenii Strains and in Saccharomyces cerevisiae

The use of seawater and marine microorganisms can represent a sustainable alternative to avoid large consumption of freshwater performing industrial bioprocesses. Debaryomyces hansenii, which is a known halotolerant yeast, possess metabolic traits appealing for developing such processes. For this purpose, we studied salt stress exposure of two D. hansenii strains isolated from marine fauna. We found that the presence of sea salts during the cultivation results in a slight decrease of biomass yields. Nevertheless, higher concentration of NaCl (2 M) negatively affects other growth parameters, like growth rate and glucose consumption rate. To maintain an isosmotic condition, the cells accumulate glycerol as compatible solute. Flow cytometry analysis revealed that the osmotic adaptation causes a reduced cellular permeability to cell-permeant dye SYBR Green I. We demonstrate that this fast and reversible phenomenon is correlated to the induction of membrane depolarization, and occurred even in presence of high concentration of sorbitol. The decrease of membrane permeability induced by osmotic stress confers to D. hansenii resistance to cationic drugs like Hygromycin B. In addition, we describe that also in Saccharomyces cerevisiae the exposure to hyper-osmotic conditions induced membrane depolarization and reduced the membrane permeability. These aspects are very relevant for the optimization of industrial bioprocesses, as in the case of fermentations and bioconversions carried out by using media/buffers containing high nutrients/salts concentrations. Indeed, an efficient transport of molecules (nutrients, substrates, and products) is the prerequisite for an efficient cellular performance, and ultimately for the efficiency of the industrial process.

Development of a high-yielding bioprocess for 11-α hydroxylation of canrenone under conditions of oxygen-enriched air supply

A high yielding bioprocess for 11-α hydroxylation of canrenone (1a) using Aspergillus ochraceus ATCC 18500 was developed. The optimization of the biotransformation involved both fermentation (for achieving highly active mycelium of A. ochraceus) and biotransformation with the aim to obtain 11-α hydroxylation with high selectivity and yield. A medium based on sucrose as C-source resulted particularly suitable for conversion of canrenone into the corresponding 11-hydroxy derivative, whereas the use of O₂-enriched air and dimethyl sulfoxide (DMSO) as a co-solvent for increasing substrate solubility played a crucial role for obtaining high yields (>95%) of the desired product in high chemical purity starting from 30mM (10.2g/L) of substrate. The structure of the hydroxylated product was confirmed by a combination of two-dimensional NMR proton-proton correlation techniques.

Enzymatic reduction of acetophenone derivatives with a benzil reductase from Pichia glucozyma (KRED1-Pglu): electronic and steric effects on activity and enantioselectivity

Enantioselective reduction of mono-substituted acetophenones by ketoreductase KRED1-Pglu.

Stereoselective reduction of aromatic ketones by a new ketoreductase from Pichia glucozyma

A new NADPH-dependent benzil reductase (KRED1-Pglu) was identified from the genome of the non-conventional yeast Pichia glucozyma CBS 5766 and overexpressed in E. coli. The new protein was characterised and reaction parameters were optimised for the enantioselective reduction of benzil to (S)-benzoin. A thorough study of the substrate range of KRED1-Pglu was conducted; in contrast to most other known ketoreductases, KRED1-Pglu prefers space-demanding substrates, which are often converted with high stereoselectivity. A molecular modelling study was carried out for understanding the structural determinants involved in the stereorecognition experimentally observed and unpredictable on the basis of steric properties of the substrates. As a result, a new useful catalyst was identified, enabling the enantioselective preparation of different aromatic alcohols and hydroxyketones.

Impact of hepatitis C virus infection on the risk of death of alcohol-dependent patients

Hepatitis C virus (HCV) infection is frequent among patients with alcohol use disorders. We aimed to analyse the impact of HCV infection on survival of patients seeking treatment for alcohol use. This was a longitudinal study in a cohort of patients who abused alcohol recruited in two detoxification units. Socio-demographic and alcohol use characteristics, liver function tests for the assessment of alcohol-related liver disease and HCV and HIV infection serologies were obtained at admission. Patients were followed until December 2008; causes of death were ascertained through clinical records and death registry. Cox models were used to analyse predictors of death. A total of 675 patients (79.7% men) were admitted; age at admission was 43.5 years (IQR: 37.9-50.2 years), duration of alcohol abuse was 18 years (IQR: 11-24 years), and median alcohol consumption was 200 g/day (IQR: 120-275 g/day). Distribution of patients according to viral infections was as follows: 75.7% without HCV or HIV infection, 14.7% HCV infection alone and 8.1% HCV/HIV coinfection. Median follow-up was 3.1 years (IQR: 1.5-5.1 years) accounting for 2,345 person-years. At the end of study, 78 patients (11.4%) had died. In the multivariate analysis, age at admission (HR = 1.71, 95%CI: 1.05-2.80), alcohol-related liver disease (HR = 3.55, 95%CI: 1.93-6.53) and HCV/HIV co-infection (HR = 3.86 95%CI: 2.10-7.11) were predictors of death. Younger patients (≤43 years) with HCV infection were more likely to die than those without viral infections (HR = 3.1, 95%CI: 1.3-7.3; P = 0.007). Among patients with alcohol-related liver disease, mortality rate was high, irrespective of viral infections. These data show that HCV infection confers a worse prognosis in patients with alcohol use disorders.

Redesigning the synthesis of vidarabine via a multienzymatic reaction catalyzed by immobilized nucleoside phosphorylases

The comparison between the biocatalyzed synthesis of araA here described and the chemical synthesis of this nucleoside showed that the enzymatic route is superior (less steps, milder conditions and reagents, easier downstream, lower E-factor).

Nucleoside 2'-deoxyribosyltransferase from psychrophilic bacterium Bacillus psychrosaccharolyticus--preparation of an immobilized biocatalyst for the enzymatic synthesis of therapeutic nucleosides

Nucleoside 2'-deoxyribosyltransferase (NDT) from the psychrophilic bacterium Bacillus psychrosaccharolyticus CECT 4074 has been cloned and produced for the first time. A preliminary characterization of the recombinant protein indicates that the enzyme is an NDT type II since it catalyzes the transfer of 2'-deoxyribose between purines and pyrimidines. The enzyme (BpNDT) displays a high activity and stability in a broad range of pH and temperature. In addition, different approaches for the immobilization of BpNDT onto several supports have been studied in order to prepare a suitable biocatalyst for the one-step industrial enzymatic synthesis of different therapeutic nucleosides. Best results were obtained by adsorbing the enzyme on PEI-functionalized agarose and subsequent cross-linking with aldehyde-dextran (20 kDa and 70% oxidation degree). The immobilized enzyme could be recycled for at least 30 consecutive cycles in the synthesis of 2'-deoxyadenosine from 2'-deoxyuridine and adenine at 37 °C and pH 8.0, with a 25% loss of activity. High conversion yield of trifluridine (64.4%) was achieved in 2 h when 20 mM of 2'-deoxyuridine and 10 mM 5-trifluorothymine were employed in the transglycosylation reaction catalyzed by immobilized BpNDT at 37 °C and pH 7.5.

Chemoenzymatic synthesis of neoglycoproteins driven by the assessment of protein surface reactivity

An efficient chemoenzymatic strategy followed by an integrated in silico and proteomic analysis for the preparation of neoglycoproteins was described.

Immobilized purine nucleoside phosphorylase from Aeromonas hydrophila as an on-line enzyme reactor for biocatalytic applications

We described the development of a biochromatographic system which uses a purine nucleoside phosphorylase from Aeromonas hydrophila (AhPNP) for the evaluation of the substrate specificity on nucleoside libraries. AhPNP has been covalently immobilized on a fused silica Open Tubular Capillary (OTC) via Schiff base chemistry. The resulting bioreactor has been characterized by the determination of kinetic constants (Km and Vmax) for a natural substrate (inosine) and then assayed versus all natural purine (deoxy)ribonucleosides and a small library of 6-substituted purine ribosides. Characterization of the bioreactor has been carried out through a bidimensional chromatographic system with the sample on-line transfer from the bioreactor to the analytical column for the separation and quantification of substrate and product. Comparison with the soluble enzyme showed that the AhPNP-based bioreactor is reliable as the same ranking order, with respect to the standard activity assay, was obtained. The stability of the IMER was also assessed and the system was found to be stable up to 60 reactions.

Modulation of the microenvironment surrounding the active site of penicillin G acylase immobilized on acrylic carriers improves the enzymatic synthesis of cephalosporins

The catalytic properties of penicillin G acylase (PGA) from Escherichia coli in kinetically controlled synthesis of β-lactam antibiotics are negatively affected upon immobilization on hydrophobic acrylic carriers. Two strategies have been here pursued to improve the synthetic performance of PGA immobilized on epoxy-activated acrylic carriers. First, an aldehyde-based spacer was inserted on the carrier surface by glutaraldehyde activation (immobilization yield = 50%). The resulting 3-fold higher synthesis/hydrolysis ratio (vs/vh₁ = 9.7 ± 0.7 and 10.9 ± 0.7 for Eupergit^® C and Sepabeads^® EC-EP, respectively) with respect to the unmodified support (vs/vh₁ = 3.3 ± 0.4) was ascribed to a facilitated diffusion of substrates and products as a result of the increased distance between the enzyme and the carrier surface. A second series of catalysts was prepared by direct immobilization of PGA on epoxy-activated acrylic carriers (Eupergit^® C), followed by quenching of oxiranes not involved in the binding with the protein with different nucleophiles (amino acids, amines, amino alcohols, thiols and amino thiols). In most cases, this derivatization increased the synthesis/hydrolysis ratio with respect to the non derivatized carrier. Particularly, post-immobilization treatment with cysteine resulted in about 2.5-fold higher vs/vh₁ compared to the untreated biocatalyst, although the immobilization yield decreased from 70% (untreated Eupergit^® C) to 20%. Glutaraldehyde- and cysteine-treated Eupergit^® C catalyzed the synthesis of cefazolin in 88% (±0.9) and 87% (±1.6) conversion, respectively, whereas untreated Eupergit^® C afforded this antibiotic in 79% (±1.2) conversion.

Retrospective study of the prevalence of postanaesthetic hypothermia in dogs

The anaesthetic records of 1525 dogs were examined to determine the prevalence of postanaesthetic hypothermia, its clinical predictors and consequences. Temperature was recorded throughout the anaesthesia. At the end of the procedure, details coded in were: hyperthermia (>39.50°C), normothermia (38.50°C-39.50°C), slight (38.49°C-36.50°C), moderate (36.49°C-34.00°C) and severe hypothermia (<34.00°C). Statistical analysis consisted of multiple regression to identify the factors that are associated with the temperature at the end of the procedure. Before premedication, the temperature was 38.7 ± 0.6°C (mean ± sd). At 60, 120 and 180 minutes from induction, the temperature was 36.7 ± 1.3°C, 36.1 ± 1.4°C and 35.8 ± 1.5°C, respectively. The prevalence of hypothermia was: slight, 51.5 per cent (95 per cent CI 49.0 to 54.0 per cent); moderate, 29.3 per cent (27.1-31.7 per cent) and severe: 2.8% (2.0-3.7%). The variables that associated with a decrease in the temperature recorded at the end of the anaesthesia were: duration of the preanesthetic time, duration of the anaesthesia, physical condition (ASA III and ASA IV dogs showed lower temperatures than ASA I dogs), the reason for anaesthesia (anaesthesia for diagnostic procedures or thoracic surgery reduce the temperature when compared with minor procedures), and the recumbency during the procedure (sternal and dorsal recumbencies showed lower temperatures than lateral recumbency). The temperature before premedication and the body surface (BS) were associated with a higher temperature at the end of the anaesthesia, and would be considered as protective factors.

Estimated liver fibrosis and its impact on all-cause mortality of HCV-monoinfected and HCV/HIV-coinfected drug users

Progression of liver fibrosis is associated with the risk of cirrhosis and end-stage liver disease. We aimed to evaluate fibrosis of the liver using three non-invasive indexes (FIB-4, Forns, and Pohl score) and its association with mortality of HCV-monoinfected and HCV/HIV-coinfected drug users.

PATIENTS AND METHODS

longitudinal study in patients admitted to substance abuse treatment between 1994 and 2006. Socio-demographic data, drug use characteristics, blood samples for laboratory tests, and serology for HIV and hepatitis C virus infections were collected at admission. Patients were followed-up until December 2006 and mortality was ascertained through hospital charts and death certificates.

RESULTS

Four hundred and ninety-seven patients were included (83.1% men); median age at admission was 31 years (IQR: 27-35). The main drugs of abuse were opiates (89.5%) and cocaine (8.3%). Thirty-two percent of patients reported daily alcohol consumption. The estimated prevalence of advanced liver fibrosis (ALF) was higher among HCV/HIV-coinfected patients (9.2% to 17.3% depending on the index analyzed) than among the HCV-monoinfected patients (3% to 3.5%). Odds ratio (OR) for ALF were 3.3 to 6.0 times higher in coinfected patients as compared to the HCV-monoinfected. After a median follow-up time of 7.7 years (IQR: 4.1-9.9 years), almost 20% of patients had died. The estimated ALF at admission was associated with an increased risk of death (RR 1.85 to 3.89 depending on the index). Among those with ALF, mortality rates were similar in HCV-monoinfected and HCV/HIV-coinfected patients, as determined by the FIB-4 and Forns indexes.

CONCLUSIONS

Estimation of liver fibrosis using serum markers may help with clinical decisions to facilitate access to treatment of chronic hepatitis C in this population.

The crystal structure of Streptococcus pyogenes uridine phosphorylase reveals a distinct subfamily of nucleoside phosphorylases

Uridine phosphorylase (UP), a key enzyme in the pyrimidine salvage pathway, catalyzes the reversible phosphorolysis of uridine or 2'-deoxyuridine to uracil and ribose 1-phosphate or 2'-deoxyribose 1-phosphate. This enzyme belongs to the nucleoside phosphorylase I superfamily whose members show diverse specificity for nucleoside substrates. Phylogenetic analysis shows Streptococcus pyogenes uridine phosphorylase (SpUP) is found in a distinct branch of the pyrimidine subfamily of nucleoside phosphorylases. To further characterize SpUP, we determined the crystal structure in complex with the products, ribose 1-phosphate and uracil, at 1.8 Å resolution. Like Escherichia coli UP (EcUP), the biological unit of SpUP is a hexamer with an α/β monomeric fold. A novel feature of the active site is the presence of His169, which structurally aligns with Arg168 of the EcUP structure. A second active site residue, Lys162, is not present in previously determined UP structures and interacts with O2 of uracil. Biochemical studies of wild-type SpUP showed that its substrate specificity is similar to that of EcUP, while EcUP is ∼7-fold more efficient than SpUP. Biochemical studies of SpUP mutants showed that mutations of His169 reduced activity, while mutation of Lys162 abolished all activity, suggesting that the negative charge in the transition state resides mostly on uracil O2. This is in contrast to EcUP for which transition state stabilization occurs mostly at O4.

Nucleoside phosphorylases from clostridium perfringens in the synthesis of 2',3'-dideoxyinosine

Four Clostridium perfringens phosphorylases were subcloned, overexpressed and analyzed for their substrate specificity. DeoD(1) and PunA could use a variety of purine substrates, including an antiviral drug 2',3'-dideoxyinosine (ddI). In one-pot synthesis using Clostridium phosphorylases, 2',3'-dideoxyuridine and hypoxanthine were converted to ddI at yield of about 30%.

[Aniridia, congenital glaucoma and white corneas in a newborn baby]

CASE REPORT

We present the case of a newborn baby in whom we observed aniridia, congenital glaucoma and edematous corneas, without clearance of the cornea after glaucoma surgery, and in whom a keratoplasty was considered. The patient had no evidence of systemic diseases and no deletion of chromosome 11.

DISCUSSION

It is important to perform a thorough ophthalmological and systemic exploration in newborn patients with aniridia due to other diseases that can be associated with it. We present the unusual case in which aniridia, congenital glaucoma and white corneas coexisted in a newborn baby. To our knowledge, such cases have only been reported twice before in the literature (Arch Soc Esp Oftalmol 2009; 84: 573-576).

Hyaluronic acid, transforming growth factor-beta1 and hepatic fibrosis in patients with chronic hepatitis C virus and human immunodeficiency virus co-infection

Chronic hepatitis C virus (HCV) infection follows an accelerated course in patients co-infected with human immunodeficiency virus (HIV); establishing the extent of liver fibrosis is crucial for disease staging and determining treatment strategy in these patients. The utility of noninvasive markers of fibrosis as alternatives to liver biopsy has not been well-studied in these patients. We evaluated the predictive value of serum transforming growth factor-beta1 (TGF-beta1) and hyaluronic acid (HA) levels for determining the extent of liver fibrosis. Liver biopsies and blood samples were collected from 69 consecutive patients (74% male; median age, 41 years) between May 2005 and November 2006. Serum TGF-beta1 and HA were analysed using commercial kits. Aspartate aminotransferase, alanine aminotransferase and gamma-glutamyl transpeptidase levels were elevated in 81%, 70% and 60% of patients, respectively. Fifty-three patients (90%) were on highly active antiretroviral therapy and the median CD4-positive cell count was 422 cells/microL. The extent of fibrosis according to Scheuer's scoring was 32% F0 (no fibrosis), 16.5% F1, 16.5% F2, 26% F3 and 7% F4 (cirrhosis). Mean serum TGF-beta1 was 36.1 +/- 14.4 ng/mL; mean serum HA was 75.2 +/- 85.0 microg/L. Serum HA was positively associated and significantly correlated with the stage of fibrosis (r = 0.56; P < 0.05). The area under the curve for discriminating mild (F0-F2) from significant (F3-F4) fibrosis in receiver operating analysis using HA was 0.83 (sensitivity, 87%; specificity, 70%). These data suggest that HA is clinically useful for predicting liver fibrosis and cirrhosis in patients co-infected with HCV/HIV. However, serum TGF-beta1 was not predictive of histological damage in co-infected individuals treated with HAART.

The impact of avoidable mortality on life expectancy at birth in Spain: changes between three periods, from 1987 to 2001

Objective:

To evaluate the impact of avoidable mortality on the changes in life expectancy at birth in Spain.

Methods:

Standard life table techniques and the Arriaga method were used to calculate and to decompose life expectancy (LE) changes by age, effects and groups of causes of avoidable mortality among three periods (1987–91, 1992–6 and 1997–2001). A list of causes of avoidable mortality reached by consensus and previously published in Spain was used.

Main results:

Life expectancy increased in all ages and both sexes. The main contribution to the increase of LE at birth was due to people over 50. Mortality in young adults produced a reduction in LE between the first two periods, but there was an important increase in LE between the last two periods; in both cases, this was the result of factors amenable to health policy interventions. The highest improvement in LE was due to non-avoidable causes, but avoidable mortality through health service interventions showed improvements in LE in those younger than 1 year and in those aged 45–75 years.

Conclusions:

Making a distinction between several groups of causes of avoidable mortality and using decomposition by causes, ages and effects allowed us to better explain the impact of avoidable mortality on the LE of the whole population and gave a new dimension to this indicator that could be very useful in public health.

New active site oriented glyoxyl-agarose derivatives of Escherichia coli penicillin G acylase

Background

Immobilized Penicillin G Acylase (PGA) derivatives are biocatalysts that are industrially used for the hydrolysis of Penicillin G by fermentation and for the kinetically controlled synthesis of semi-synthetic β-lactam antibiotics. One of the most used supports for immobilization is glyoxyl-activated agarose, which binds the protein by reacting through its superficial Lys residues. Since in E. coli PGA Lys are also present near the active site, an immobilization that occurs through these residues may negatively affect the performance of the biocatalyst due to the difficult diffusion of the substrate into the active site. A preferential orientation of the enzyme with the active site far from the support surface would be desirable to avoid this problem.

Results

Here we report how it is possible to induce a preferential orientation of the protein during the binding process on aldehyde activated supports. A superficial region of PGA, which is located on the opposite side of the active site, is enriched in its Lys content. The binding of the enzyme onto the support is consequently forced through the Lys rich region, thus leaving the active site fully accessible to the substrate. Different mutants with an increasing number of Lys have been designed and, when active, immobilized onto glyoxyl agarose. The synthetic performances of these new catalysts were compared with those of the immobilized wild-type (wt) PGA. Our results show that, while the synthetic performance of the wt PGA sensitively decreases after immobilization, the Lys enriched mutants have similar performances to the free enzyme even after immobilization.

We also report the observations made with other mutants which were unable to undergo a successful maturation process for the production of active enzymes or which resulted toxic for the host cell.

Conclusion

The desired orientation of immobilized PGA with the active site freely accessible can be obtained by increasing the density of Lys residues on a predetermined region of the enzyme. The newly designed biocatalysts display improved synthetic performances and are able to maintain a similar activity to the free enzymes. Finally, we found that the activity of the immobilized enzyme proportionally improves with the number of introduced Lys.

Anatomy of the temporomandibular joint

The temporomandibular joint (TMJ), also known as the mandibular joint, is an ellipsoid variety of the right and left synovial joints forming a bicondylar articulation. The common features of the synovial joints exhibited by this joint include a fibrous capsule, a disk, synovial membrane, fluid, and tough adjacent ligaments. Not only is the mandible a single bone but the cranium is also mechanically a single stable component; therefore, the correct terminology for the joint is the craniomandibular articulation. The term temporomandibular joint is misleading and seems to only refer to one side when referring to joint function. Magnetic resonance imaging has been shown to accurately delineate the structures of the TMJ and is the best technique to correlate and compare the TMJ components such as bone, disk, fluid, capsule, and ligaments with autopsy specimens.

[Has gallbladder cancer mortality decrease in Chile?]

This paper analyses the information of the Ministry of Health on gallbladder cancer mortality in Chile since 1997. It becomes evident that the decrease in mortality in the last two years is only apparent and due to a statistical artifact, caused by the non validated application of the Tenth International Classification of Diseases. There is a consensus that one of the causes for an increase in gallbladder cancer in a specific country is a decrease in cholecystectomy rates. This association has been clearly demonstrated in Chile, but no control program for gallbladder cancer has been devised, considering that an early cholecystectomy is a good secondary prevention measure.

[A universal method to correct underreporting of communicable diseases. Real incidence of hydatidosis in Chile, 1985-1994]

BACKGROUND

There is evidence to postulate that undernotification is the reason for the great decrease in the reported incidence of hydatidosis in Chile.

AIM

To develop and propose a method to assess the notification of transmissible diseases, based on observed lethality and hospital discharges.

MATERIAL AND METHODS

Human hydatidosis in the period 1985-1994 was used as a model to develop the method. Official reports and mortality were analyzed first, determining the first lethality rate. A second lethality rate was calculated based on hospital discharges and a third, based on all Chilean surgical series published in the last two decades. Adjusting official notification of lethality to the true lethality according to surgical series, the number of unreported cases was calculated and the true incidence of hydatidosis was calculated, summing these cases to the official notification.

RESULTS

According to this method, the real rates of human hydatidosis in the period 1985-1994, would fluctuate between 6.5 and 11.4 per 100,000. This figure is four times higher than the official notification in the analysed period.

CONCLUSIONS

The correction of under notification based on hospital discharges, with or without correction for repeated hospital admissions, or real mortality of surgical series gave similar results, suggesting that both methods are correct.

[Acetaminophen hepatotoxicity in an alcohol addicted student. Case report]

We report a 12 years old male with a history of excessive alcohol intake, that developed a severe liver failure after the use of acetaminophen in therapeutic doses. He presented with encephalopathy, jaundice, fever and an upper gastrointestinal bleeding. Serum aspartate aminotransferase values were 5,250 IU/L. The patient received supportive care and oral corticosteroids, remained severely compromised for 72 hours and had a good evolution thereafter. The association of acetaminophen use and excessive alcohol intake in a patient who developed an acute hepatic failure and the absence of serological evidence of hepatitis A or B viral infection, support the diagnosis of drug induced liver failure.

[Nutritional risk factors for gallstones. Epidemiological analysis]

This article reviews the role of nutrition in the incidence of gallstones. The epidemiological situation of gallbladder disease has wide worldwide geographical variations, being Pima Indians and the Chileans the most affected populations. The main nutritional risk factor is obesity. Other risk are serum cholesterol and triglyceride levels, unbalanced and excessive caloric intake, fasting periods of more than eight hours, hypocaloric diets of less than 700 Kcal/day, specially in obese subjects and parenteral nutrition lasting more than two weeks. The main conclusion of this revision is that nutritional behaviors of the population must be improved through public health programs, to reduce the incidence of obesity and related nutritional imbalances.