Ozonation of ciprofloxacin in water: HRMS identification of reaction products and pathways

Degradation products formed during ozonation of an aqueous solution of the antibiotic ciprofloxacin in a bubble column are analyzed by HPLC-UV high-resolution mass spectrometry. Based on the identification of the reaction products, reaction pathways are proposed starting with (1) degradation at the piperazinyl substituent, (2) degradation at the quinolone moiety with formation of isatin analogues, and (3) degradation at the quinolone moiety with formation of anthranilic acid analogues. Unlike H2O2 addition (10 microM), pH (3,7, and 10) strongly affects degradation product formation during ozonation. Degradation at the quinolone core is favored at pH 7. Addition of t-butanol, a hydroxyl radical scavenger, ruled out formation of isatin and anthranilic acid analogues. Because the carboxylic group and the keto group at the quinolone moiety are essential for antibacterial activity, degradation at pH 7 seems to be promising for reduction of bacterial resistance against quinolones in contaminated water.     

Comparison between MAP and postprocessed ML for image reconstruction in emission tomography when anatomical knowledge is available

Previously, the noise characteristics obtained with penalized-likelihood reconstruction [or maximum a posteriori (MAP)] have been compared to those obtained with postsmoothed maximum-likelihood (ML) reconstruction, for emission tomography applications requiring uniform resolution. It was found that penalized-likelihood reconstruction was not superior to postsmoothed ML. In this paper, a similar comparison is made, but now for applications where the noise suppression is tuned with anatomical information. It is assumed that limited but exact anatomical information is available. Two methods were compared. In the first method, the anatomical information is incorporated in the prior of a MAP-algorithm and is, therefore, imposed during MAP-reconstruction. The second method starts from an unconstrained ML-reconstruction, and imposes the anatomical information in a postprocessing step. The theoretical analysis was verified with simulations: small lesions were inserted in two different objects, and noisy PET data were produced and reconstructed with both methods. The resulting images were analyzed with bias-noise curves, and by computing the detection performance of the nonprewhitening observer and a channelized Hotelling observer. Our analysis and simulations indicate that the postprocessing method is inferior, unless the noise correlations between neighboring pixels are taken into account. This can be done by applying a so-called prewhitening filter. However, because the prewhitening filter is shift variant and object dependent, it seems that MAP reconstruction is the more efficient method.     

Culturomics to Investigate the Endometrial Microbiome: Proof-of-Concept

The microbiome of the reproductive tract has been associated with (sub)fertility and it has been suggested that dysbiosis reduces success rates and pregnancy outcomes. The endometrial microbiome is of particular interest given the potential impact on the embryo implantation. To date, all endometrial microbiome studies have applied a metagenomics approach. A sequencing-based technique, however, has its limitations, more specifically in adequately exploring low-biomass settings, such as intra-uterine/endometrial samples. In this proof-of-concept study, we demonstrate the applicability of culturomics, a high-throughput culturing approach, to investigate the endometrial microbiome. Ten subfertile women undergoing diagnostic hysteroscopy and endometrial biopsy, as part of their routine work-up at Brussels IVF, were included after their informed consent. Biopsies were used to culture microbiota for up to 30 days in multiple aerobic and anaerobic conditions. Subsequent WASPLab^®-assisted culturomics enabled a standardized methodology. Matrix-assisted laser desorption/ionization–time of flight mass spectrometry (MALDI-TOF MS) or 16S rRNA sequencing was applied to identify all of bacterial and fungal isolates. Eighty-three bacterial and two fungal species were identified. The detected species were in concordance with previously published metagenomics-based endometrial microbiota analyses as 77 (91%) of them belonged to previously described genera. Nevertheless, highlighting the added value of culturomics to identify most isolates at the species level, 53 (62.4%) of the identified species were described in the endometrial microbiota for the first time. This study shows the applicability and added value of WASPLab^®-assisted culturomics to investigate the low biomass endometrial microbiome at a species level.     

Nocturnal tidal barrier management improves glass eel migration in times of drought and salinization risk

Adjusted tidal barrier management (ATBM, setting tidal doors ajar during tidal rise) is currently applied in Belgium to improve glass eel passage through tidal gates. However, salt intrusion in the receiving waters due to upwelling and accumulation of saline groundwater as a result of intensive drought put severe pressure on the unrestrained use of this cost-efficient mitigation measure. We evaluated the efficacy of a very restricted ATBM at a tidal barrier on a small canalized waterway, located 3.5 km from the sea: one out of seven gate doors was left 20 cm ajar for ca. 30 min when the water levels on both sides of the tidal barrier were approximately equal. During 20 inflow events differing in tidal flow (i.e., flood or ebb tide) and daytime (i.e., day or night) in March/April 2019, migrating glass eels were caught with a fyke net fixed on the temporally opened gate. In total, 12,853 glass eels were captured, almost all during flood tides at night (96%), with a maximum catch of 3,827 individuals per inflow event. These results show that even small windows of opportunity can help glass eels pass tidal barriers.