Temporal and spatial variation of phosphate distribution in the sediment of a free water surface constructed wetland

This study was aimed at determining the spatial and temporal variation of P distribution in sediment of an artificial wetland for sewage and industrial wastewater treatment, and the fraction that is potentially involved in the P exchange processes. Influent, effluent, macrophytes and sediment at the inlet, middle and outlet areas were sampled over 24 months. The P-fractionation in sediment was performed following the EDTA method. Eichhornia crassipes and Typha domingensis removed P efficiently when cover was high, but E. crassipes caused anoxic conditions. The increase in cover of T. domingensis may contribute to attain oxic conditions and to improve P removal. When macrophytes are not present or when cover is low, sediment seems to increase removal efficiency. A significant increase in the concentration of the fraction of Fe(OOH) approximately P and mainly that of CaCO(3) approximately P can be observed at the inlet. High pH, Ca(2+) and CO(3)(-)(2) concentrations in the influent suggest that P co-precipitates together with CaCO(3). Therefore, it seems that CaCO(3) approximately P represents the main precipitating mechanism. However, mineralization of organic matter maintained the sediment at a pH range lower than the high values prevailing in the influent. CO(3)(-)(2) could undergo partial dissolution and the released i-P(diss) could be readsorbed onto the Fe(OOH) approximately P fraction. Since the environment for P retention (high pH, Fe, Ca and ionic concentrations) is largely provided by the influent, the wetland may be expected to continue retaining P as far as the composition of the influent is maintained and there are available adsorption sites in the sediment.

Hepatitis A virus detection in food: current and future prospects

Hepatitis A virus (HAV) is responsible for around half of the total number of hepatitis infections diagnosed worldwide. HAV infection is mainly propagated via the faecal-oral route and as a consequence of globalisation, transnational outbreaks of foodborne infections are reported with increasing frequency. Molecular procedures are now available and should be employed for the direct surveillance of HAV in food and environmental samples.

Attachment of enteric viruses to bottles

Storage of water that was deliberately contaminated with enteric viruses in polyethylene terephthalate (PET) bottles led to a rapid decrease of the apparent viral load, thereby hampering the development of samples for a collaborative evaluation of viral detection methods for bottled water. To determine if this decrease was due to spontaneous inactivation or to adhesion, an elution protocol was developed and combined with a rapid and sensitive real-time reverse transcription-PCR-based method to quantify adsorbed norovirus (NV), hepatitis A virus (HAV), and rotavirus (RV) on bottle walls. The NV retention on PET bottle walls after 20 and 62 days reached an average level of 85% and 95% of the recovered inoculum, respectively. HAV and RV also showed adsorption onto PET bottles, reaching 90% and 80%, respectively, after 20 days of storage. NV and RV attachment was demonstrated to be dependent on the presence of autochthonous flora, whereas HAV adsorption was independent of it. Application of the elution and viral detection protocol to 294 commercially available water bottles obtained from 25 different countries did not give any positive result, thereby providing further evidence that the sources used for this product are free from enteric viruses and support for the theory that bottled water is not a vehicle for viral diseases.

Removal efficiency of a constructed wetland for wastewater treatment according to vegetation dominance

A free water surface wetland was built to treat wastewater containing metals (Cr, Ni and Zn) and nutrients from a tool factory in Santo Tomé, Santa Fe, Argentina. Eichhornia crassipes became dominant and covered about 80% of the surface throughout the first year, and decreased progressively until its disappearance. When water depth was lowered Typha domingensis steadily increased plant cover and attained 30% of the surface by the end of the study. While E. crassipes was dominant, the wetland retained 62% of the incoming Cr and 48% of the Ni. NO3- and NO2-, were also removed (65% and 78%, respectively), while dissolved inorganic phosphate (i-P(diss)) and NH4+ were not removed. Zn was below 50 microg l(-1) in both the influent and effluent. Metal concentration in the sediments did not increase and retention was mediated through macrophytes uptake. During the period of E. crassipes decline the wetland retained 49% of the incoming Cr, 45% of Ni, 58% NO3-, 94% NO2-, 58% NH4+ and 47% i-P(diss). Cr, Ni and Zn in the bottom sediment increased in the inlet but not in the outlet. Since T. domingensis became dominant, retention was 58% Cr, 48% Ni and 64% i-P(diss), while 79% NO3-, 84% NO2- and 13% NH4+ were removed. Metals in the bottom sediment increased in the inlet. In spite of the significant growth of E. crassipes at the beginning, T. domingensis remained after most of the transplanted macrophytes had disappeared. Macrophyte disappearance could be related to the overall toxicity of several environmental constrains as high pH and conductivity, metal concentration, and sulphide presence.

Polarization insensitive low-loss coupling technique between SOI waveguides and high mode field diameter single-mode fibers

A polarization insensitive technique for highly efficient coupling between SOI waveguides and high mode field diameter single-mode fibers is reported. The proposed coupling structure is based on an inverted taper structure coupled to a fiber-adapted waveguide. The fiber-adapted waveguide is made by using the SiO(2) layer under the Si waveguiding layer of the SOI wafer thus avoiding the use of extra materials such as polymers. The proposed coupling structure is aimed for being integrated with V-groove auto-alignment techniques. Coupling losses of 3.5dB and 3.7dB to 8mum mode field diameter single-mode fibers have been estimated by means of 3D-BPM simulations for TE and TM polarizations respectively and a 1550nm input signal wavelength.

Structure determination of di-mu-hydroxo-bis[(2-(2-pyridyl)phenyl-kappa2N,C1)palladium(II)] by X-ray powder diffractometry

The title compound was synthesized in the form of a powder, and was studied by elemental analysis, IR spectroscopy, thermogravimetry and mass spectroscopy. Its crystal structure was then determined by X-ray powder diffractometry, using X-ray diffraction data collected in the reflection Bragg-Brentano geometry. The methodology followed in the present study to resolve the crystal structure consisted of peak indexing, then the use of the Monte-Carlo/parallel tempering search algorithm, and finally Rietveld refinement coupled with difference-Fourier synthesis. We found that the crystals are composed of monoclinic unit cells, with 1.5 molecules in the asymmetric unit and therefore six molecules per unit cell. In addition, we concluded that the complexes adopt a planar conformation, forming trimers created by groups of parallel molecules.

Cadmium and chromium removal kinetics from solution by two aquatic macrophytes

The aim of this work was to determine chromium and cadmium bioaccumulation processes of two free-floating macrophytes commonly used in wetlands for water treatment: Salvinia herzogii and Pistia stratiotes. Metal removal from the solution involves two stages: a fast one and a slow one. The fast stage of the Cd uptake is significantly different for each species, while it is not significantly different in Cr uptake. The most important processes of Cd uptake are biological ones in S. herzogii and adsorption, chelation and ionic exchange are in P. stratiotes. The main processes of Cr uptake in both macrophytes are adsorption, chelation and ion exchange. The slow stage is different for each species and metal. Cr precipitation induced by roots occurs in P. stratiotes. Cr uptake through leaves is probably the main cause of the increase of Cr in the aerial parts of S. herzogii.

Optimal design and mathematical model applied to establish bioassay programs

Bioassays can be used to estimate the initial intake I for the case of an acute intake exposure for an individual worker. To evaluate the effective dose, apart from I, we need to know other parameters such as activity median aerodynamic diameter (AMAD) or the fraction absorption ( f(1)) in the blood from the GI tract, but in an accident situation these parameters are often unknown. The bioassay measurement values can be used to estimate by fitting the parameters unknown. In this paper, optimal designs for the estimation of the unknown parameters are developed. The efficiency of the design will depend on the number of samples and the measurement accuracy. The method described applies D-optimality that maximises the determinant of the Fisher information matrix to find the best moments where the bioassay measurements should be taken. It requires obtaining the analytical solution of the biokinetic model as a function of the parameters to be fitted. The method has been implemented in a computer program.

Procedure for rapid concentration and detection of enteric viruses from berries and vegetables

Several hepatitis A virus (HAV) and norovirus (NV) outbreaks due to consumption of berries and vegetables have been reported during recent years. To facilitate the detection of enteric viruses that may be present on different fresh and frozen products, we developed a rapid and sensitive detection method for HAV, NV, and rotavirus (RV). Initial experiments focused on optimizing the composition of the elution buffer, improving the viral concentration method, and evaluating the performance of various extraction kits. Viruses were extracted from the food surface by a direct elution method in a glycine-Tris (pH 9.5) buffer containing 1% beef extract and concentrated by ultrafiltration. Occasionally, PCR inhibitors were present in the processed berry samples, which gave relatively poor detection limits. However, this problem was overcome by adding a pectinase treatment in the protocol, which markedly improved the sensitivity of the method. After optimization, this concentration method was applied in combination with real-time reverse transcription-PCR (RT-PCR) using specific primers in various types of berries and vegetables. The average detection limits were 1 50% tissue culture infective dose (TCID(50)), 54 RT-PCR units, and 0.02 TCID(50) per 15 g of food for HAV, NV, and RV, respectively. Based on our results, it is concluded that this procedure is suitable to detect and quantify enteric viruses within 6 h and can be applied for surveillance of enteric viruses in fresh and frozen products.

Liver Transplantation: Experience With Our First 100 Cases

OBJECTIVES

Our goal was to evaluate the results of the first 100 liver transplants performed in our institution.

METHODS

We retrospectively analyzed the first 100 liver transplants undertaken in adults from November 2001 to August 2005.

RESULTS

The mean age of the recipients was 50 years (20 to 69) and 73% were men. The mean waiting time was 35 days. The mean age of the donors was 60 years (15 to 87), and 60% were men. One-year patient and graft survival rates were 93% and 90%, respectively. Three-year patient and graft survival rates were 85% and 82%, respectively. The need for retransplantation was 3%. Surgical complications included hepatic artery stenoses, 2%; hepatic artery thromboses, 2%; biliary leaks, 6%; and biliary stenoses, 14%.

CONCLUSIONS

These results are no different from the overall results for liver transplantation in Spain during the same period.

Monitoring the efficacy of specific treatment in chronic Chagas disease by polymerase chain reaction and flow cytometry analysis

PCR and FC-ALTA were used to monitor parasite clearance in 54 chronic chagasic patients who had completed therapy with allopurinol (ALLO, n = 31) or itraconazole (ITRA, n = 23) ten years earlier. All patients maintained positive conventional serology. 25 of them showed positive XD (ALLO, n = 11 and ITRA, n = 14) and 29 negative XD (ALLO, n = 20 and ITRA, n = 9). 43 patients were positive by both techniques (ALLO, n = 23 and ITRA, n = 20). Seven of 54 patients were negative by PCR and positive by FC-ALTA and three of 54 were positive by PCR and negative by FC-ALTA. Only one case with both tests negative should be considered cured. Of 29 patients with negative XD, 14 treated ALLO (70 %) and nine with ITRA (77.8 %) showed positive PCR and FC-ALTA. These results do not show differences of efficacy among the drugs, and reinforce the relevance of using sensitive tools such as PCR and FC-ALTA for the follow-up of patients with chronic Chagas disease.

Detection and differentiation of human hepatitis A strains by commercial quantitative real-time RT-PCR tests

Performance characteristics of two commercial quantitative Hepatitis A virus (HAV) RT-PCR assays, the LightCycler Hepatitis A virus quantification kit (Roche Diagnostics) and the RealArt HAV LC RT PCR kit (artus GmbH) for detection and quantification of HAV were evaluated. Both assays rely on reverse transcription and amplification of extracted RNA. Dilutions of two HAV strains, belonging to different subtypes, were prepared to determine the precision, accuracy, linearity and the detection limit. Both assays were found to be suitable for quantification measurement of HAV RNA, but only the Roche kit was able to distinguish the different HAV strains tested. The linear range for the artus assay was 10(4)-10(6)IU/ml and 2 x 10(4) to 2 x 10(8) RNA copies/ml for the Roche assay. The detection limit of Roche kit was 2 TCID(50)/ml or 500 RNA copies/ml and 5 TCID(50)/ml or 50 IU/ml for the artus kit. Despite these small differences it is concluded that both assays are very suitable for detection and quantification of most prevalent HAV subtypes.

[Prevalence of attention deficit hyperactivity disorder in Colombian children and teenagers]

INTRODUCTION

Attention deficit hyperactivity disorder (ADHD) is the most common neurobehavioural disorder among schoolchildren. It may persist into adulthood and affect performance in the academic, social, occupational and familial spheres, and increase the use and abuse of alcohol and psychoactive substances and the risk of having an accident. Its prevalence throughout the world varies widely and further knowledge about this situation would be valuable for the development of policies in the sector of education.

AIMS

The aim of this research was to determine the prevalence of ADHD and its distribution according to subtypes in schoolchildren from Sabaneta, Antioquia, Colombia, in 2001.

SUBJECTS AND METHODS

The analysis involved a cross-sectional descriptive study using a representative randomised multistage sample (which was proportional to the size of the groups) of schoolchildren between 4 and 17 years old. Measurement was performed in two stages, first by application of a screening form according to DSM IV criteria, and later a structured interview, Conners' and Intelligence tests.

RESULTS

Prevalence was found to be 20.4% and 15.8% if only children with an intelligence quotient of 80 or above were considered. The combined subtype was the most frequent, with 9.6%. In public schools it was 16.2%, private 15.3%, age group from 7-11 years 16.9%, 12-17 years old 14.2%, males 20.9%, females 10.1%, low 14.7%, medium 17.4% and high socioeconomic level 10.7%, with a male to female prevalence ratio of 3.88 to 1.

CONCLUSIONS

Prevalence of ADHD in the school population in a municipality in the Metropolitan Area of Medellin, Colombia, is high. The most frequent subtype was the combined type, which was predominant in males, had repercussions on academic performance and low proportions of pharmacological interventions for the disorder (15%). Programmes must be developed for the detection of this problem and subsequent intervention in the school population.

Effects of effervescent ranitidine on gastric pH: comparison with almagate and placebo in fasting and postprandial conditions

AIM

To compare the effect of effervescent ranitidine, almagate (magnesium carbonate-aluminium hydroxide) and placebo on gastric pH, in fasting and postprandial conditions.

METHODS

Twelve healthy volunteers underwent a gastro-oesophageal pH monitoring on three different occasions after the administration of each of the following randomly allocated treatments: almagate, effervescent ranitidine and placebo. Treatment effects were assessed in fasting and postprandial conditions. Onset and duration of alkalinization, percentage of time with pH > 4 and median gastric pH after treatments were calculated in both periods.

RESULTS

Onset of action of effervescent ranitidine was similar to almagate in fasting [median 1.2 min (IQR: 0.6-12.7) vs. 2.9 min (0.4-227.6)] and postprandial conditions [1.4 min (0.5-4.9) vs. 4.1 min (1.3-63.8)] and both were significantly faster than placebo [fasting 211.1 min (2.7-240); postprandial 240 min (175.6-240)]. The duration of action of effervescent ranitidine was statistically significant longer than almagate in fasting [235 min (105.2-239.4) vs. 19.4 min (6.7-38.8)] and postprandial conditions [171.8 min (133.2-239.5) vs. 61.3 min (44.7-91.9)]. Effervescent ranitidine was more effective than almagate in increasing the percentage of time with a pH > 4 both in fasting (73.9% vs. 7.3%) and postprandial (59.1% vs. 21.3%).

CONCLUSIONS

Effervescent ranitidine shows an effect on gastric pH as fast as almagate but provides a duration of alkalinization longer than almagate, in both fasting and postprandial conditions.