Pollutant removal in a multi-stage municipal wastewater treatment system comprised of constructed wetlands and a maturation pond, in a temperate climate.

A multi-stage municipal wastewater treatment system is proposed to comply with Mexican standards for discharge into receiving water bodies. The system is located in Santa Fe de la Laguna, Mexico, an area with a temperate climate. It was designed for 2,700 people equivalent (259.2 m3/d) and consists of a preliminary treatment, a septic tank as well as two modules operating in parallel, each consisting of a horizontal subsurface-flow wetland, a maturation pond and a vertical flow polishing wetland. After two years of operation, on-site research was performed. An efficient biochemical oxygen demand (BOD5) (94-98%), chemical oxygen demand (91-93%), total suspended solids (93-97%), total Kjeldahl nitrogen (56-88%) and fecal coliform (4-5 logs) removal was obtained. Significant phosphorus removal was not accomplished in this study (25-52%). Evapotranspiration was measured in different treatment units. This study demonstrates that during the dry season wastewater treatment by this multi-stage system cannot comply with the limits established by Mexican standards for receiving water bodies type 'C'. However, it has demonstrated the system's potential for less restrictive uses such as agricultural irrigation, recreation and provides the opportunity for wastewater treatment in rural areas without electric energy.

A common FADS2 promoter polymorphism increases promoter activity and facilitates binding of transcription factor ELK1.

Fatty acid desaturases (FADS) play an important role in the formation of omega-6 and omega-3 highly unsaturated fatty acids (HUFAs). The composition of HUFAs in the human metabolome is important for membrane fluidity and for the modulation of essential physiological functions such as inflammation processes and brain development. Several recent studies reported significant associations of single nucleotide polymorphisms (SNPs) in the human FADS gene cluster with HUFA levels and composition. The presence of the minor allele correlated with a decrease of desaturase reaction products and an accumulation of substrates. We performed functional studies with two of the associated polymorphisms (rs3834458 and rs968567) and showed an influence of polymorphism rs968567 on FADS2 promoter activity by luciferase reporter gene assays. Electrophoretic mobility shift assays proved allele-dependent DNA-binding ability of at least two protein complexes to the region containing SNP rs968567. One of the proteins binding to this region in an allele-specific manner was shown to be the transcription factor ELK1 (a member of ETS domain transcription factor family). These results indicate that rs968567 influences FADS2 transcription and offer first insights into the modulation of complex regulation mechanisms of FADS2 gene transcription by SNPs.

Bioinformatic identification and characterization of new members of short-chain dehydrogenase/reductase superfamily.

With about 60 genes known in the human genome, short-chain dehydrogenases/reductases (SDRs) form a large gene family with important implications for medicine. They are known to be involved in carcinogenesis (e.g. breast and prostate cancer) as well as in metabolic and degenerative defects such as the pathogenesis of Alzheimer's disease, osteoporosis and diabetes. Uncharacterized SDRs are thus potential candidates for many monogenic and multifactorial human diseases. The identification and functional analysis of such SDR enzymes is therefore the primary goal of the study leading to new targets for drug development. In all taxa (bacteria, plants, insects, vertebrates), members of SDR superfamily are known. Up to now, there are several thousand members annotated many of which have not been characterized biochemically with regard to enzymatic activity, substrate specificity, or subcellular localization. We bioinformatically identified 250 vertebrate candidate genes belonging to the SDR superfamily using the BioNetWorks software SDR finder. The number was reduced to 95 after continuative analysis, including manual SDR motif verification and focus on human, rat and murine enzymes. Here, we present several new mammalian SDRs that were clustered into several enzymatically different groups by detailed phylogenetic analyses. Furthermore, characteristic mRNA expression patterns were identified for some of these genes by a recently developed in silico Northern blot method supporting their putative functions in retinoid, steroid, sugar and other metabolic pathways.

Interspecies comparison of gene structure and computational analysis of gene regulation of 17beta-hydroxysteroid dehydrogenase type 1.

17Beta-hydroxysteroid dehydrogenase type 1 (HSD17B1) is a key enzyme of 17beta-estradiol biosynthesis, and in rodents is additionally involved in testosterone biosynthesis. The human HSD17B1 gene, located on chromosome 17q12-21, is duplicated in tandem, with the 3'-copy being the functional gene. Here we show by sequencing the gene from a diverse set of related species that this duplication is of very recent evolutionary origin, having occurred in the common ancestor of Hominoidae (apes and humans) while being absent in the closely related Old World monkeys (Macaca) and the outgroup species Tupaia belangeri and Mus musculus. By computational analysis of the conserved regulatory elements in the 5'-untranslated (5'-UTR) and putative promoter region of the HSD17B1 gene and, where present, pseudogene, across our broad sample of species we can show significant differences that might point to the origin of the divergent substrate specificity of human and rodent HSD17B1 and highlight potential functionally relevant differences in regulatory patterns in different evolutionary lineages.

Androgen metabolism via 17beta-hydroxysteroid dehydrogenase type 3 in mammalian and non-mammalian vertebrates: comparison of the human and the zebrafish enzyme.

Formation and inactivation of testosterone is performed by various members of the 17beta-hydroxysteroid dehydrogenase (17beta-HSD) family. The main player in testosterone formation is considered to be 17beta-HSD type 3, which catalyzes the reduction of androstenedione to testosterone with high efficiency and is almost exclusively expressed in testis. So far, only the mammalian homologs have been characterized but nothing is known about the role of 17beta-HSD type 3 in other vertebrates. In this study, we describe the identification and characterization of the zebrafish homolog. We found zebrafish 17beta-HSD type 3 to be expressed in embryogenesis from sphere to 84 h post-fertilization. Expression was also detected in various tissues of both male and female adults, but displayed sexual dimorphism. Interestingly, expression was not highest in male testis but in male liver. In female adults, strongest expression was observed in ovaries. At the subcellular level, both human and zebrafish 17beta-HSD type 3 localize to the endoplasmic reticulum. The zebrafish enzyme in vitro effectively catalyzed the conversion of androstenedione to testosterone by use of NADPH as cofactor. Among further tested androgens epiandrosterone and dehydroepiandrosterone were accepted as substrates and reduced at C-17 by the human and the zebrafish enzyme. Androsterone and androstanedione though, were only substrates of human 17beta-HSD type 3, not the zebrafish enzyme. Furthermore, we found that both enzymes can reduce 11-ketoandrostenedione as well as 11beta-hydroxyandrostenedione at C-17 to the respective testosterone forms. Our results suggest that 17beta-HSD type 3 might play slightly different roles in zebrafish compared with human although testosterone itself is likely to have similar functions in both organisms.

Application of sandwich immunoassays for the determination of sample-specific background signals and its use for calibration of immunoassays.

Sample-related background signals in immunoassays can be measured by a variation of the double antibody sandwich principle, in which the unlabelled specific antibody is substituted by a similar unrelated non-specific antibody. This permits differentiation between the analyte-specific and the background signal components for each sample. The method permits selection of sera with no or low analyte content for use as analyte diluent and for defining the zero point of the calibration curve. The method also permits control of analyte content during production processes which may change the background signal as well as identification of samples with atypical background signals. The procedure has been used for the calibration of enzyme immunoassays for alpha-fetoprotein (AFP) and human thyroid-stimulating hormone (TSH).

AADE guidelines. Infection control guidelines for patient education as a means of preventing blood-borne disease transmission during diabetes self-care procedures.

There exists a potential for blood-borne disease transmission with many diabetes self-care behaviors. It is necessary for the diabetes educator to instruct the patient regarding infection-control practices.

Characterization and dewaterability of raw and stabilized sludge using different treatment methods.

A comparison of the characteristics and stabilization potential of the four most used sludge treatment systems in Mexico was made. A pilot plant constituted by separate systems for anaerobic and aerobic digestion, lime stabilization, conditioning and dewatering, was built and operated during four months in one of the biological wastewater treatment plants in Acapulco, Mexico. Composting of sludge was also made. An aerobic static pile was built using bulking materials available in the region. A turbine centrifuge was used for dewatering the stabilized sludge and results showed good performance of the device. The main problem for the beneficial use of treated sludge was its pathogenicity. The composting process allowed us to obtain a product with approximately 20 fecal coliform density (MPN/g); with lime stabilization, the sludge produced had a fecal coliform density of 2 MPN/g. From these results, it is concluded that both the composting process and the alkaline stabilization with lime produce a well stabilized sludge, bacteriologically safe that accomplishes the requirements for its use on soil without restrictions. Related to parasitological removal, the best helminth egg removals were obtained also using these two processes. Ascaris sp. densities in raw sludge (309-430 eggs/g) were reduced to a final density of 3-14 eggs/g in the aerobic composting process and to 4-18 eggs/g in the lime stabilized sludge. Removal is not high enough to reach the recommended level for unrestricted use of stabilized sludge.

Alternative treatment strategy for tannery water reuse and material recovery.

Most tanneries use conventional systems for treatment of the mixture of all production effluents. Such an approach makes it possible to meet environmental regulations, but because of the high cost of the treatment facilities, its implementation has been scarce, especially in developing countries. With the waste reduction-elimination concept in view, an alternative strategy for water management is proposed based on individual treatment of the effluents from different processing steps to obtain multiquality recycled water for various reuse purposes, materials recovery and complete reuse of treated water. The methodology includes a database generation of tanneries in Mexico, a mass balance and pollution index determination, formulation of water management scenarios and technical-economical evaluation. To replace the traditionally used sulfde oxidation, a sulfide recovering was proposed. Chromium, grease and protein recovery were considered too. The proposed alternative allows a 90% fresh water reduction, the recovery of more than 95% of chromium and sulfide, 90% of grease, 65% of protein and zero discharge of wastewater. Simultaneous implementation of various water saving methods using in-house wastewater treatment techniques for recovering of chemicals and sub-products reduces substantially the cost of water management.

Effect of brief, repeated hyperbaric exposures on susceptibility to nitrogen narcosis.

We investigated the effect of brief, repetitive exposures to 5.5 ATA (148 fsw) in a hyperbaric chamber on adaptation to nitrogen narcosis. A standing-steadiness task, which measures body sway, was administered to 2 groups of 3 chamber-qualified men at 5.5 ATA and 1.3 ATA [10 fsw (control)] on each of 12 successive days to determine if an initial performance decrement at 5.5 ATA would be ameliorated with time. Standing steadiness was significantly worse at 5.5 ATA than at 1.3 ATA across all 12 exposures. There were also changes in standing steadiness from day to day, but these changes occurred in both the test and control depths. There was no day-x-depth interaction that would have indicated that the initial performance decrement at 5.5 ATA was reduced with repetitive exposures. These results are taken as evidence that there is little or no behavioral adaptation to nitrogen narcosis in response to brief, repetitive exposures to narcosis-inducing hyperbaric air.

Operations planning with VERT.

The Venture Evaluation and Review Technique (VERT) is a computerized, mathematically oriented network-based simulation technique designed to analyze risk existing in three parameters of most concern to managers in new projects or ventures--time, cost, and performance. As such, the VERT technique is more powerful than techniques such as GERT, which are basically time and cost oriented. VERT has been successfully utilized to assess the risks involved in new ventures and projects, in the estimation of future capital requirements, in control monitoring, and in the overall evaluation of ongoing projects, programs, and systems. It has been helpful to management in cases where there is a requirement to make decisions with incomplete or inadequate information about the alternatives. An example describing the application of VERT to an operational planning problem--the evaluation of electric power generating methods--is illustrated.

Computer-aided medical diagnosis: literature review.

The difficulty of the medical diagnostic task and the advantages of the computer as an aid in this task are discussed. The general strategy and structure of any computer-aided system is presented, and the relationship of diagnostic accuracy to key variables involved in the development, test and use of a computer-aided diagnostic system is examined. These variables include: the computer algorithm, the source of the information used to develop the data base, the number and type of diseases under investigation, the number and type of indicants used, the source of the test sample, and the source of the validated diagnosis. A table of 58 empirically tested computer-aided medical diagnostic systems is presented; each system is summarised in relation to the variables mentioned above and diagnostic accuracy.

A novel 17beta-hydroxysteroid dehydrogenase in the fungus Cochliobolus lunatus: new insights into the evolution of steroid-hormone signalling.

17beta-Hydroxysteroid dehydrogenase (17beta-HSD) from the filamentous fungus Cochliobolus lunatus (17beta-HSDcl) catalyses the reduction of steroids and of several o- and p-quinones. After purification of the enzyme, its partial amino acid sequence was determined. A PCR fragment amplified with primers derived from peptide sequences was generated for screening the Coch. lunatus cDNA library. Three independent full-length cDNA clones were isolated and sequenced, revealing an 810-bp open reading frame encoding a 270-amino-acid protein. After expression in Escherichia coli and purification to homogeneity, the enzyme was found to be active towards androstenedione and menadione, and was able to form dimers of Mr 60000. The amino acid sequence of the novel 17beta-HSD demonstrated high homology with fungal carbonyl reductases, such as versicolorin reductase from Emericella nidulans (Aspergillus nidulans; VerA) and Asp. parasiticus (Ver1), polyhydroxynaphthalene reductase from Magnaporthe grisea, the product of the Brn1 gene from Coch. heterostrophus and a reductase from Colletotrichum lagenarium, which are all members of the short-chain dehydrogenase/reductase superfamily. 17beta-HSDcl is the first discovered fungal 17beta-hydroxysteroid dehydrogenase belonging to this family. The primary structure of this enzyme may therefore help to elucidate the evolutionary history of steroid dehydrogenases.