Occurrence, formation and persistence of halobenzoquinones: A case study on 2, 6 -dichloro-1, 4 -benzoquinone

Halobenzoquinones (HBQs) constitute an emerging class of potentially carcinogenic disinfection by-products (DBPs). Given that HBQs are not measured in routine analysis of drinking water, there is little data on their occurrence in the USA. The presence of 2, 6-dichloro-1, 4-benzoquinone (2, 6-DCBQ) in US drinking water facilities was investigated in 8 utilities to provide an initial assessment of occurrence and fate in relation to the regulated DBPs. Point of entry (POE) and distribution system (DS) samples with DCBQ concentrations greater than the 90th percentile values were from treatment plants that used free chlorine. Across distribution systems, DCBQ exhibited decreasing concentrations with water age whereas trihalomethane (THM) concentrations increased with water age. In an effort to better understand the source of DBP precursors, controlled laboratory experiments were conducted to examine the formation of DCBQ from chlorination and chloramination of specific classes of lignin model compounds namely p-hydroxyl phenols, vanillyn, syringyl and cinnamyl phenols, poly phenols and alkoxy groups. DCBQ yields from chlorination depended on the type and position of the substituents and potential intermediates and varied between n.d-0.8 percent while chloramination did not result in DCBQ formation. Chlorination of p-hydroxyl phenols produced the highest DCBQ yield for the reaction period considered (6 h). To address the apparent loss of DCBQ in full-scale systems, the impact of different pHs on DCBQ degradation at ambient temperature was investigated and modeled. DCBQ remained relatively stable below pH 7 while the degradation rate above this pH was determined to be first order in [OH-] with a second order rate constant of 156 M-1 s-1

Case of placental insufficiency and premature delivery in a Fontan pregnancy:physiological insights and considerations on risk stratification

Objectives The coexistence of two complex physiologies such as Fontan and pregnancy is still not fully understood. We aim to add a unique and essential knowledge to help our colleagues in the management of Fontan patients that undergo pregnancy as well as the fetus and the placenta perfusion.Methods and results We analyse the coexistence of Fontan and pregnancy physiology on a complex case of a woman with hypoplastic left heart syndrome palliated with a univentricular repair who became pregnant, delivered very prematurely and had atypical placental findings.Conclusion Histopathological analysis of the placenta could help us to refine the understanding of Fontan physiology adaptation during pregnancy, predict women and fetal outcomes as well as to plan a better pre-pregnancy status. However, further evidence is needed in order to reach a more solid and unified conclusion

Standards for the provision of antenatal care for patients with inflammatory bowel disease: guidance endorsed by the British Society of Gastroenterology and the British Maternal and Fetal Medicine Society

Background: Pregnant women with inflammatory bowel disease (IBD) are at increased risk of adverse pregnancy outcomes. Comprehensive guidelines on medical management have been published; yet, there is limited guidance on service set-up and minimum standards of care for pregnant women with IBD. Aim: To develop a position statement on service set-up and minimum standards of care in the UK. Methods: A working group consisting of 16 gastroenterologists, obstetricians, obstetric physician, IBD specialist nurses and midwives was assembled. Initial draft statements were produced and a modified Delphi process with two rounds of voting applied. Statements were modified according to voters’ feedback after each round. Statements with ≥80% agreement were accepted. Results: All 15 statements met criteria for inclusion. To facilitate optimal care, regular and effective communication between IBD and obstetric teams is required. There should be nominated link clinicians for IBD in obstetric units and for pregnancy in IBD units. Preconception counselling should be available for all women with IBD. All pregnant women should be advised on the safety of IBD medication during pregnancy and breast feeding, the optimal mode of delivery, the management of biologics (where applicable) and safety of childhood vaccinations. Regular audit of pregnancy outcomes and documentation of advice given is recommended. Conclusion: Position statements have been developed that advise on the importance of joined-up multidisciplinary care, proactive decision-making with clear documentation and communication to the woman and other healthcare practitioners

Associations of the built environment with type 2 diabetes in Asia: a systematic review

Objectives Our study aimed to systematically review the literature and synthesise findings on potential associations of built environment characteristics with type 2 diabetes (T2D) in Asia. Design Systematic review of the literature. Data sources Online databases Medline, Embase and Global Health were used to identify peer-reviewed journal articles published from inception to 23 January 2023. Eligibility criteria Eligible studies included cohort, cross-sectional and case–control studies that explored associations of built environment characteristics with T2D among adults 18 years and older in Asia. Data extraction and synthesis Covidence online was used to remove duplicates and perform title, abstract and full-text screening. Data extraction was carried out by two independent reviewers using the OVID database and data were imported into MS Excel. Out of 5208 identified studies, 28 studies were included in this systematic review. Due to heterogeneity in study design, built environment and outcome definitions, a semiqualitative analysis was conducted, which synthesised results using weighted z-scores. Results Five broad categories of built environment characteristics were associated with T2D in Asia. These included urban green space, walkability, food environment, availability and accessibility of services such as recreational and healthcare facilities and air pollution. We found very strong evidence of a positive association of particulate matter (PM2.5, PM10), nitrogen dioxide and sulfur dioxide (p<0.001) with T2D risk. Conclusion Several built environment attributes were significantly related to T2D in Asia. When compared with Western countries, very few studies have been conducted in Asia. Further research is, therefore, warranted to establish the importance of the built environment on T2D. Such evidence is essential for public health and planning policies to (re)design neighbourhoods and help improve public health across Asian countries

Common variants in CLDN2 and MORC4 genes confer disease susceptibility in patients with chronic pancreatitis

A recent Genome-wide Association Study (GWAS) identified association with variants in X-linked CLDN2 and MORC4 and PRSS1-PRSS2 loci with Chronic Pancreatitis (CP) in North American patients of European ancestry. We selected 9 variants from the reported GWAS and replicated the association with CP in Indian patients by genotyping 1807 unrelated Indians of Indo-European ethnicity, including 519 patients with CP and 1288 controls. The etiology of CP was idiopathic in 83.62% and alcoholic in 16.38% of 519 patients. Our study confirmed a significant association of 2 variants in CLDN2 gene (rs4409525—OR 1.71, P = 1.38 x 10-09; rs12008279—OR 1.56, P = 1.53 x 10-04) and 2 variants in MORC4 gene (rs12688220—OR 1.72, P = 9.20 x 10-09; rs6622126—OR 1.75, P = 4.04x10-05) in Indian patients with CP. We also found significant association at PRSS1-PRSS2 locus (OR 0.60; P = 9.92 x 10-06) and SAMD12-TNFRSF11B (OR 0.49, 95% CI [0.31–0.78], P = 0.0027). A variant in the gene MORC4 (rs12688220) showed significant interaction with alcohol (OR for homozygous and heterozygous risk allele -14.62 and 1.51 respectively, P = 0.0068) suggesting gene-environment interaction. A combined analysis of the genes CLDN2 and MORC4 based on an effective risk allele score revealed a higher percentage of individuals homozygous for the risk allele in CP cases with 5.09 fold enhanced risk in individuals with 7 or more effective risk alleles compared with individuals with 3 or less risk alleles (P = 1.88 x 10-14). Genetic variants in CLDN2 and MORC4 genes were associated with CP in Indian patients

Analysis and Fate of 2,6-Dichloro-1,4-Benzoquinone in Real and Model Drinking Waters

For many years chlorination has served as a barrier to protect human health from waterborne disease outbreaks. Chlorine is viewed as a near-universal oxidant and disinfectant, that provides a stable residual preventing microbial re-growth all the way through the consumer’s tap. Upon reaction with natural organic matter (NOM) however, it forms disinfection by-products (DBPs) many of which are potent human carcinogens and therefore have been of research interest since the 1970’s (Froese et al., 1999; Krasner et al., 2006, 1989; Richardson, 2003; Rook, 1976, 1974; Singer, 1994). The trihalomethanes (THMs) and haloacetic acids (HAAs) are the most prevalent (Krasner et al., 1989) and routinely monitored and, the only ones regulated by the United States Environmental Protection Agency (USEPA) (80 ppb for THMs and 60 ppb for HAAs) (USEPA, 2006). The focus has recently shifted to the emerging DBP classes over concerns of even higher toxicity, carcinogenicity and mutagenicity (Bull, 1982; Hrudey, 2009; Plewa et al., 2004a, 2004b; Richardson et al., 2007). Halobenzoquinones (HBQs) are emerging DBPs that are postulated drivers of bladder carcinogenicity. Prior assessments of 2,6-dichloro-1,4-benzoquinone (DCBQ) occurrence in drinking water distribution systems have revealed a gradual decline with increasing distance from points of entry. While this signals a degradation pathway, there is limited quantitative data on rate of that degradation. A systematic evaluation of DCBQ hydrolysis was performed, resulting in a rate law that is first order in both hydroxide [OH-] and [DCBQ]. The impact of temperature on that rate was characterized according to the Arrhenius relationship. Under the conditions tested (pH~7.2, T = 20 °C) chloramine did not significantly impact DCBQ concentrations. However, DCBQ was rapidly degraded in solutions containing free available chlorine (FAC). Kinetic analysis showed non-integer order with respect to FAC. Further investigation led to a model that invoked reaction with dichlorine monoxide (Cl2O) as well as FAC. Such fast degradation of DCBQ, in the presence of free chlorine seem incompatible with the high concentrations reported for this emerging disinfection by-product in many drinking water distribution systems. In an effort to reconcile these two, a series of laboratory experiments and field tests was conducted. These eventually focused on evaluating the use of formic acid alone as a preservative without use of a conventional reducing agent. Formic acid was found to inadequately reduce free chlorine, resulting in persisting chlorine residuals during sample workup and analysis. The low pH used for sample preservation along with a free residual appeared to catalyze additional DCBQ formation provided that organic precursors were still present in the sample. This led to large errors and positive analytical bias. For future testing, the recommended protocol calls for addition of either glycine or arsenite followed by formic acid. Studies published without fully quenching chlorine residuals should be regarded with caution. Little is known about the nature of HBQ precursors or about strategies for minimizing HBQs formation. Through a controlled laboratory study using solutions of pure natural organic matter (NOM) model compounds, phenolic structures containing activating -OH group with vacant ortho/para positions were determined to be plausible precursors to DCBQ, the most common of the HBQs. Almost all of the reactions proceeded through a 2,4,6-trichlorophenol pathway. Chlorination experiments conducted on a raw water and two relatively high DCBQ yielding p-hydroxy aromatic molecules (p-hydroxybenzoic acid and its aldehyde) revealed similar DBP trends. In each case, the rank order of resulting DBPs is: trichloroacetic acid\u3e chloroform\u3e dichloroacetic acid\u3e DCBQ. The same solutions were subjected to preoxidation using ozone (O3) and chlorine dioxide (ClO2) at three different doses followed by chlorination. Both strong oxidants successfully decreased the tendency of the model compounds to produce DCBQ upon subsequent chlorination, however some increases in regulated DBPs were noted. When working with raw waters pretreatment with ClO2 resulted in about 35% less DCBQ after chlorination, whereas no impact was observed for O3. Such differences between preoxidant effectiveness in the raw water and model compound solutions can be attributed to the inhibiting effect of the raw water matrix and therefore very high doses are required for considerable DCBQ precursor removal in raw waters with high specific ultraviolet absorbance (SUVA254) values

The Role of Stretch of the Amnion in the Biochemistry of Human Labour

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Erosion infiltration technique': A novel alternative for masking enamel white spot lesion

Enamel White spot lesions are early signs of demineralization under the intact enamel, which may or may not lead to the development of caries. An inactive white spot lesion might act as an arrested dental caries and impair the esthetic appearance by displaying a milky white color from its interior opacity. The first choice of treatment is remineralization with various remineralizing agents such as fluoride and ACP-CCP. Caries infiltration is a less invasive and effective method for arresting the white spot lesions. It also improves the esthetics by masking the chalky white appearance by the process of optical adaptation to the adjacent healthy enamel. This is achieved by the hydrophobic resin, which has a similar refractive index to that of the healthy enamel

Modeling Crude Oil Fate and Transport in Freshwater

Accidental contaminant spills in surface freshwater drinking sources put the public at risk, lower consumer confidence, and are costly to clean up. Although crude oil is commonly transported in close proximity to drinking water supplies, much of the research has focused on the fate and transport of crude oil in marine and riverine systems, not reservoirs. This study illustrates an application of a proactive spill modeling method to simulate crude oil fate and transport in a reservoir using a combination of laboratory and modeling investigation. Dissolution trends of benzene, toluene, and ethylbenzene from hypothetical accidental input scenarios were estimated by solid-phase micro-extraction combined (SPME) with gas chromatography mass spectrometry (GC/MS) methods. Laboratory dissolution trends informed inputs to a hydrodynamic and water quality model, CE-QUAL-W2, which simulated the fate and transport of the crude oil components within a reservoir with a focus on water quality impacts at the drinking water intake. The method can be applied to proactively quantify and scientifically guide emergency response planning and management of drinking water reservoirs in the event of an crude oil accidental spill