Partial nitrification of ammonium to nitrite under oxic conditions (nitritation) is a critical process for the effective use of alternative nitrogen removal technologies from wastewater. Here we investigated the conditions which promote establishment of a suitable microbial community for performing nitritation when starting from regular sewage sludge. Reactors were operated in duplicate under different conditions (pH, temperature, and dilution rate) and were fed with 50 mM ammonium either as synthetic medium or as sludge digester supernatant. In all cases, stable nitritation could be achieved within 10 to 20 days after inoculation. Quantitative in situ hybridization analysis with group-specific fluorescent rRNA-targeted oligonucleotides (FISH) in the different reactors showed that nitrite-oxidizing bacteria of the genus Nitrospira were only active directly after inoculation with sewage sludge (up to 4 days and detectable up to 10 days). As demonstrated by quantitative FISH and restriction fragment length polymorphism (RFLP) analyses of the amoA gene (encoding the active-site subunit of the ammonium monooxygenase), the community of ammonia-oxidizing bacteria changed within the first 15 to 20 days from a more diverse set of populations consisting of members of the Nitrosomonas communis and Nitrosomonas oligotropha sublineages and the Nitrosomonas europaea-Nitrosomonas eutropha subgroup in the inoculated sludge to a smaller subset in the reactors. Reactors operated at 30°C and pH 7.5 contained reproducibly homogeneous communities dominated by one amoA RFLP type from the N. europaea-N. eutropha group. Duplicate reactors at pH 7.0 developed into diverse communities and showed transient population changes even within the ammonia oxidizer community. Reactors at pH 7.5 and 25°C formed communities that were indistinguishable by the applied FISH probes but differing in amoA RFLP types. Communities in reactors fed with sludge digester supernatant exhibited a higher diversity and were constantly reinoculated with ammonium oxidizers from the supernatant. Therefore, such systems could be maintained at a higher dilution rate (0.75 day ؊1 compared to 0.2 day ؊1 for the synthetic wastewater reactors). Despite similar reactor performance with respect to chemical parameters, the underlying community structures were different, which may have an influence on stability during perturbations.Strong regulations exist nowadays for the removal of ammonium from wastewater discharge. Ammonium can lead to eutrophication of freshwater bodies and is toxic to aquatic life (11). The current method of removal of ammonium in wastewater treatment plants consists of a combination of aerobic nitrification catalyzed by autotrophic organisms and anaerobic denitrification catalyzed by heterotrophic organisms (40). In a first step, ammonium is oxidized to nitrate via nitrite, and in a second step, nitrate is reduced with organic carbon via nitrite to N 2 . This combination was long considered as the only way to remove ammonium from wastewater. However, m...

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Background: The coronary artery calcium score (CACS) is a powerful tool for cardiovascular risk stratification. Coronary computed tomography angiography (CTA) allows for a more distinct analysis of atherosclerosis. The aim of the study was to assess gender differences in the atherosclerosis profile of CTA in patients with a CACS of zero. Methods: A total of 1451 low- to intermediate-risk patients (53 ± 11 years; 51% females) with CACS <1.0 Agatston units (AU) who underwent CTA and CACS were included. Males and females were 1:1 propensity score-matched. CTA was evaluated for stenosis severity (Coronary Artery Disease – Reporting and Data System (CAD-RADS) 0–5: minimal <25%, mild 25–49%, moderate 50–69%, severe ≥70%), mixed-plaque burden (G-score), and high-risk plaque (HRP) criteria (low-attenuation plaque, spotty calcification, napkin-ring sign, and positive remodeling). All-cause mortality, cardiovascular mortality, and major cardiovascular events (MACEs) were collected. Results: Among the patients, 88.8% had a CACS of 0 and 11.2% had an ultralow CACS of 0.1–0.9 AU. More males than females (32.1% vs. 20.3%; p < 0.001) with a CACS of 0 had atherosclerosis, while, among those with an ultralow CACS, there was no difference (88% vs. 87.1%). Nonobstructive CAD (25.9% vs. 16.2%; p < 0.001), total plaque burden (2.2 vs. 1.4; p < 0.001), and HRP were found more often in males (p < 0.001). After a follow-up of mean 6.6 ± 4.2 years, all-cause mortality was higher in females (3.5% vs. 1.8%, p = 0.023). Cardiovascular mortality and MACEs were low (0.2% vs. 0%; p = 0.947 and 0.3% vs. 0.6%; p = 0.790) for males vs. females, respectively. Females were more often symptomatic for chest pain (70% vs. 61.6%; p = 0.004). (4) Conclusions: In patients with a CACS of 0, males had a higher prevalence of atherosclerosis, a higher noncalcified plaque burden, and more HRP criteria. Nonetheless, females had a worse long–term outcome and were more frequently symptomatic.

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Background & aims: Data on the effects omega-3 fatty acids on coronary artery disease (CAD) are contradictory. While a recent metanalysis could not show improved cardiovascular outcomes, antiatherogenic mechanisms are well known. Objective: Aim was to assess the influence of Omega-3 polyunsaturated long-chain fatty acids (PUFA) supplementation on coronary atherosclerosis quantified by coronary computed tomography angiography (CTA). Methods: 106 patients (59.4y± 10.7; 50% females) with low-to-intermediate risk referred to CTA were included. 53 patients under omega 3-PUFA (docosahexaenoic acid, DHA and eicosapentaenoic acid, EPA) supplementation were retrospectively matched with 53 controls (CR) for age, gender and coronary risk profile (smoking, arterial hypertension, family history, dyslipidemia, c-LDL, Cholesterol, TG, diabetes) (1:1, propensity score) and lifestyle habits (exercise, alcohol consumption and nutrition). CTA analysis included 1) stenosis severity score >70%severe, 50e70% moderate, 25e50%mild, <25% minimal), 2) total plaque burden (segment involvement score (SIS) and mixed non-calcified plaque burden (G-score) and 3) high-risk-plaque features (Napkin-Ring-Sign, low attenuation plaque (LAP), spotty calcification<3 mm, RI>1.1). CT-Density (Hounsfield Units, HU) of plaque was quantified by CTA. Results: Prevalence of coronary atherosclerosis (any plaque: 83% vs. 90.6%, p ¼ 0.252), >50% stenosis and stenosis severity score (p ¼ 0.134) were not different between groups. Total and non-calcified plaque burden scores were lower in the omega-3 group (2.7 vs. 3.5, p ¼ 0.08 and 4.5 vs. 7.4, p ¼ 0.027 for SIS and G-score, resp.). Coronary artery calcium score (CACS) was similar (84.7 vs. 87.1AU). High-risk-plaque prevalence was lower in the Omega-3 group (3.8% vs. 32%, p < 0.001); the number of high-risk-plaques (p < 0.001) and Napkin-Ring-Sign prevalence was lower (3.8% vs. 20.9%) (p < 0.001), resp. CT-density (HU) of plaque was higher in the Omega-3 group (131.6 ± 2 vs. 62.1 ± 27, p ¼ 0.02) indicating more fibrous-dense plaque component rather than lipid-rich atheroma. Mean duration of Omega-3 intake was 38.6 ± 52 months (range, 2e240). Conclusions: Omega-3-PUFA supplementation is associated with less coronary atherosclerotic "highrisk" plaque (lipid-rich) and lower total non-calcified plaque burden independent on cardiovascular risk factors. Our study supports direct anti-atherogenic effects of Omega-3-PUFA.