Stable performance of non-aerated two-stage partial nitritation/anammox (PANAM) with minimal process control

Partial nitritation/anammox (PANAM) technologies have rapidly developed over the last decade, but still considerable amounts of energy are required for active aeration. In this study, a non-aerated two-stage PANAM process was investigated. In the first-stage upflow fixed-film bioreactor, nitratation could not be prevented at ammonium loading rates up to 186 mg N l-1 d-1 and low influent dissolved oxygen (0.1 mg O2 l-1). Yet, increasing the loading rate to 416 and 747 mg N l-1 d-1 by decreasing the hydraulic retention time to 8 and 5 h, respectively, resulted in partial nitritation with the desired nitrite to ammonium nitrogen ratio for the subsequent anammox stage (0.711.05). The second-stage anammox reactor was established with a synthetic feeding based on ammonium and nitrite. After establishing anammox at low biomass content (0.5 g VSS l-1), the anammox influent was switched to partial nitritation effluent at a loading rate of 71 mg N l-1 d-1, of which 78% was removed at the stoichiometrically expected nitrite to ammonium consumption ratios (1.19) and nitrate production to ammonium consumption ratio (0.24). The combined PANAM reactors were operated for 3 months at a stable performance. Overall, PANAM appeals economically, saving about 50% of the energy costs, as well as technically, given straightforward operational principles

DNA linkage based diagnosis of Wilson disease in asymptomatic siblings

Wilson disease (WD) is an autosomal recessive disorder caused by defects in ATP7B gene located in chromosome 13q14, and manifested as hepatolenticular degeneration as a result of accumulation of copper. No information on the mutation in the ATP7B gene and haplotypes using linked markers is available for WD patients in India. Hence, the present study was undetaken to identify, by a PCR-based molecular diagnostic test, presymptomatic siblings of WD affected individuals in families with multiple offspring. Methods: Genomic DNA was prepared from the peripheral blood of the patients, siblings and his/her first degree relatives. The repeat-markers flanking WD locus were amplified by PCR using fluorescent labeled primers. Amplified DNA fragments were analyzed by polyacrylamide gel electrophoresis in ABI 377 DNA sequencing system. Genotypes of the samples were determined using Genescan software. Haplotypes were determined based on segregation of the alleles in the families under study. Results: Among 15 WD affected families with multiple children, 4 cases were identified where younger siblings shared same genotype as the patient at all three markers analyzed. Further, eight different haplotypes were detected in the four patients. Interpretation & conclusion: The siblings of the WD patients carrying the same genotype at the markers linked to WD locus were presymptomatically diagnosed individuals. Presence of eight different haplotypes in the four patients suggested mutational heterogeneity at the WD locus. The test helps clinicians for therapeutic intervention in suspect WD cases by copper chelating agents prior to manifestation of overt clinical symptoms. Key words ATP7B - genotype - haplotype - microsatellite - Wilson disease (WD) is a genetic disorder, which manifests as hepatolenticular degeneration as a result of accumulation of copper in the brain, liver, kidney and cornea due to its deranged biliary excretion1. In 1912, a WD was described as a familial syndrome of progressive lenticular degeneration associated with cirrhosis of the liver2. The etiological role of copper in the pathogenesis of WD was recognized much late

Genetic Variants Associated with Arsenic Susceptibility: Study of Purine Nucleoside Phosphorylase, Arsenic (+3) Methyltransferase, and Glutathione S-Transferase Omega Genes

BACKGROUND: Individual variability in arsenic metabolism may underlie individual susceptibility toward arsenic-induced skin lesions and skin cancer. Metabolism of arsenic proceeds through sequential reduction and oxidative methylation being mediated by the following genes: purine nucleoside phosphorylase (PNP), arsenic (+3) methyltransferase (As3MT), glutathione S-transferase omega 1 (GSTO1), and omega 2 (GSTO2). PNP functions as arsenate reductase; As3MT methylates inorganic arsenic and its metabolites; and both GSTO1 and GSTO2 reduce the metabolites. Alteration in functions of these gene products may lead to arsenic-specific disease manifestations. OBJECTIVES: To find any probable association between arsenicism and the exonic single nucleotide polymorphisms (SNPs) of the above-mentioned arsenic-metabolizing genes, we screened all the exons in those genes in an arsenic-exposed population. METHODS: Using polymerase chain reaction restriction fragment length polymorphism analysis, we screened the exons in 25 cases (individuals with arsenic-induced skin lesions) and 25 controls (individuals without arsenic-induced skin lesions), both groups drinking similar arsenic-contaminated water. The exonic SNPs identified were further genotyped in a total of 428 genetically unrelated individuals (229 cases and 199 controls) for association study. RESULTS: Among four candidate genes, PNP, As3MT, GSTO1, and GSTO2, we found that distribution of three exonic polymorphisms, His20His, Gly51Ser, and Pro57Pro of PNP, was associated with arsenicism. Genotypes having the minor alleles were significantly overrepresented in the case group: odds ratio (OR) = 1.69 [95% confidence interval (CI), 1.08–2.66] for His20His; OR = 1.66 [95% CI, 1.04–2.64] for Gly51Ser; and OR = 1.67 [95% CI, 1.05–2.66] for Pro57Pro. CONCLUSIONS: The results indicate that the three PNP variants render individuals susceptible toward developing arsenic-induced skin lesions. KEY WORDS: arsenic, As3MT, GSTO1, GSTO2, PNP, skin lesion, susceptibility. Environ Health Perspect 116:501–505 (2008). doi:10.1289/ehp.10581 available via http://dx.doi.org/ [Online 14 January 2008

Distribution of p53 codon 72 polymorphism in Indian primary open angle glaucoma patients

Purpose: Glaucoma is a complex neurodegenerative disorder of the eye. Primary Open Angle Glaucoma (POAG) is the most common type, accounting for over half of the total cases. Recently, a significant difference in the distribution of the codon 72 polymorphism of the tumor suppressor gene p53 between control subjects and POAG patients of Chinese origin (p=0.00782) was demonstrated. The proline residue at codon 72 of the p53 gene was significantly over represented in the POAG patients relative to healthy controls. The purpose of this study was to investigate whether the reported association between the p53 polymorphism and POAG is a common phenomenon irrespective of geographical location or ethnicity of the population. Methods: Sixty seven unrelated POAG patients, ranging from 10-65 years of age (mean±SD of 41.16±18.52 years), and 112 control subjects having a similar age range of 18-63 years (mean±SD of 36.64±14.65 years) were enrolled in this study. A region of the p53 gene encompassing two polymorphic sites, a 16 bp duplication in intron 3 and a BstU I RFLP in exon 4, were amplified by polymerase chain reaction from Indian POAG patients and normal healthy controls. A single base change (G to C) in codon 72 alters the amino acid residue from arginine to proline and removes the polymorphic BstU I site mentioned above. The amplified DNA fragments were digested with the restriction enzyme and the digestion patterns of the fragments were used to identify the alleles for both the polymorphic sites. Results: No significant association between p53 alleles and Indian POAG patients were observed by analyzing either codon 72 polymorphism (p=0.5627) or the intronic 16 bp duplication polymorphism (p=0.059). Haplotype analysis, reported to be a better predictor of association of the p53 gene with different types of cancer, was also performed and no association of any haplotype was detected with POAG (p=0.1831). Conclusions: Association between the p53 gene encoding for proline at codon 72 and POAG presumably exists in some ethnic populations but cannot be used as a predictor for the role of the gene as a common regulator of cell death of retinal ganglions leading to POAG

Enhanced Frequency of Micronuclei in Individuals Exposed to Arsenic Through Drinking Water in West Bengal, India

InWest Bengal, India arsenic in ground water has been found to be above the maximum permissible limit in seven districts covering an area of 37,493 km2. In the present study, evaluation of the micronuclei (MN) formation in oral mucosa cells, urothelial cells and peripheral blood lymphocytes was carried out in the symptomatic individuals exposed to arsenic through drinking water. Forty five individuals with cutaneous signs of arsenicism from four affected districts (368.11�g/l of As in drinking water) were considered as the exposed group and 21 healthy individuals with no symptoms of arsenic poisoning and residing in two unaffected districts (5.49�g/l of As) were considered as controls. The exposed and control groups had similar age distribution and socioeconomic status. Standardised questionnaires were utilised and medical examination was conducted to ascertain exposure history, sociodemographic characteristics, diet, health, medication, addiction and chief symptoms in the study participants. Arsenic exposure was confirmed by measuring the arsenic content in the drinking water, nails, hair and urine samples from the volunteers. Arsenic contents in the urine, nail and hair in the exposed group were 24.45�g/l, 12.58 and 6.97�g/g, respectively which were significantly high in comparison to corresponding control group values of 4.88�g/l, 0.51 and 0.34�g/g, respectively. Exposed individuals showed a statistically significant increase in the frequency of MN in oral mucosa, urothelial cells and lymphocytes (5.15, 5.74 and 6.39/1000 cells, respectively) when compared with the controls (0.77, 0.56 and 0.53/1000 cells, respectively). Thus, the above results indicate that the symptomatic individuals exposed to arsenic through drinking water in this region have significant cytogenetic damage. © 2002 Elsevier Science B.V

Additional file 11: of Genetic association and stress mediated down-regulation in trabecular meshwork implicates MPP7 as a novel candidate gene in primary open angle glaucoma

Represents association data of AFAP1 SNP in discovery and validation phase. (XLSX 9 kb