Polyurethane-Degrading Potential of Alkaline Groundwater Bacteria

Plastic waste is a global environmental burden and long-lasting plastic polymers, including ubiquitous and toxic polyurethanes (PUs), rapidly accumulate in the water environments. In this study, samples were collected from the three alkaline groundwater occurrences in the geotectonic regions of the Pannonian basin of northern Serbia (Torda and Slankamen Banja) and Inner Dinarides of western Serbia (Mokra Gora) with aim to isolate and identify bacteria with plastic- and lignocellulose-degrading potential, that could be applied to reduce the burden of environmental plastic pollution. The investigated occurrences belong to cold, mildly alkaline (pH: 7.6-7.9) brackish and hyperalkaline (pH: 11.5) fresh groundwaters of the SO4 - Na + K, Cl - Na + K and OH, Cl - Ca, Na + K genetic type. Full-length 16S rDNA sequencing, using Oxford Nanopore sequencing device, was performed with DNA extracted from colonies obtained by cultivation of all groundwater samples, as well as with DNA extracted directly from one groundwater sample. The most abundant genera belong to Pseudomonas, Acidovorax, Kocuria and Methylotenera. All screened isolates (100%) had the ability to grow on at least 3 of the tested plastic and lignocellulosic substrates, with 53.9% isolates degrading plastic substrate Impranil® DLN-SD (SD), a model compound for PUs degradation. Isolates degrading SD that were identified by partial 16S rDNA sequencing belong to the Stenotrophomonas, Pseudomonas, Paraburkholderia, Aeromonas, Vibrio and Acidovorax genera. Taking into account that plastics, including commonly produced PUs, are widespread in groundwater, identification of PUs-degrading bacteria may have potential applications in bioremediation of groundwater polluted with this polymer.

Brackish Groundwaters Contain Plastic- and Cellulose-Degrading Bacteria

The selected brackish groundwater occurrences in the geotectonic regions of Inner Dinarides of western Serbia (Obrenovačka Banja) and Serbian crystalline core (Lomnički Kiseljak and Velika Vrbnica) were sampled for isolation and identification of plastic- and lignocellulose-degrading bacteria, as well as for the assessment of their enzymatic potential. The examined occurrences belong to the cold and warm (subthermal), weakly alkaline, neutral, and weakly acidic groundwater, and their genetic types are HCO3-Na + K and HCO3-Ca, Mg. The most abundant genera identified by next-generation 16S sequencing of cultivated groundwater samples belong to Aeromonas and Exiguobacterium. Of isolates screened on plastic and lignocellulosic substrates, 85.3% demonstrated growth and/or degrading activity on at least one tested substrate, with 27.8% isolates degrading plastic substrate Impranil® DLN-SD (SD), 1.9% plastic substrate bis(2-hydroxyethyl)terephthalate, and 5.6% carboxymethyl cellulose (CMC). Isolates degrading SD that were identified by 16S rDNA sequencing belonged to genera Stenotrophomonas, Flavobacterium, Pantoea, Enterobacter, Pseudomonas, Serratia, Acinetobacter, and Proteus, while isolates degrading CMC belonged to genera Rhizobium and Shewanella. All investigated brackish groundwaters harbor bacteria with potential in degradation of plastics or cellulose. Taking into account that microplastics contamination of groundwater resources is becoming a significant problem, the finding of plastic-degrading bacteria may have potential in bioremediation treatments of polluted groundwater. Subterranean ecosystems, which are largely untapped resources of biotechnologically relevant enzymes, are not traditionally considered the environment of choice for screening for plastic- and cellulose-degrading bacteria and therefore deserve a special attention from this aspect.

Disruption of Estrogenic and Androgenic Bioactivities in Human Fetuses Exposed to Maternal Smoking

Endocrine disruptors (EDs) interfere with hormonal signalling and, given that multiple developmental processes are hormone-driven, the prenatal period is a window of increased sensitivity. Maternal smoking is a real-life model of in utero exposure to a complex mixture of EDs. Cigarette smoke contains of >7,000 pollutants, including polycyclic aromatic hydrocarbons (PAHs), which are AhR ligands and cross-talk with the estrogen receptor (ER) system. Prenatal exposure to cigarette smoke is associated with adverse outcomes, including intrauterine growth restriction and increased risk of metabolic syndrome later in life. We aimed to evaluate ED effects associated with smoke exposure in human fetuses. Fetal tissues (plasma, n=48; placenta, n=30; liver, n=29) from elective terminations of normally progressing pregnancies, ranging from 10 to 20 gestation weeks, were collected (SAFeR and FEGO studies: REC 15/NS/0123, REC 04/S0802/21). PAHs and PAH-like compounds were extracted from placenta and fetal liver. Bioactivity levels in plasma, placenta and liver extracts were determined using ER and androgen receptor (AR) transactivation reporter gene assays. PAH burden was evaluated using the AhR-responsive DR_hp-CALUX assay. Smoke exposure was associated with a 1.3-fold increase in plasma estrogenic activity. The developmental trajectory of androgenic activity was altered in plasma of smoke-exposed fetuses, with significant anti-androgenic activity in older fetuses (>16 weeks of gestation). In males, plasma androgenic activity was positively associated with testes weight and anogenital distance. In contrast, placentas from smoking mothers had significantly increased androgenic potential. Furthermore, AhR-like activity was 2.9-fold higher in smoke-exposed placentas compared to controls, and 2.3-fold higher in female compared to male fetal livers. Overall, all bioactivity levels were higher in placentas compared to fetal liver. Prenatal exposure to cigarette smoke is associated with higher placental AhR activation, indicative of increased xenotoxicants burden. We also report that smoke-exposed fetuses showed increased circulating estrogenic activity and disrupted androgenic potential, across 10-20 weeks of gestation, in both fetal plasma and placenta. This demonstrates that EDs present in cigarette smoke are able to interfere with hormonal signalling and alter dynamic endocrine activity profiles, which are critical to ensure appropriate, sex-specific, development. These ED effects are likely to disturb placental function and reprogramme fetal development and thus impacting on life-long health.

Induction of AhR transactivation by PBDD/Fs and PCDD/Fs using a novel human-relevant, high-throughput DRhuman CALUX reporter gene assay

Polychlorinated dioxins and dibenzofurans (PCDD/Fs) are highly toxic contaminants that are strictly regulated and monitored in the environment and food to reduce human exposure. Recently, the increasing occurrence of polybrominated dioxins and dibenzofurans (PBDD/Fs) in the environment is raising concerns about the impact on human health by the combined exposure to chlorinated and brominated analogues of dioxins. Toxicological properties of PBDD/Fs relative to PCDD/Fs have not been firmly established, and brominated dioxins are not included in routine monitoring programs. In this study, we set out to determine human-relevant congener-specific potency values for a range of brominated and chlorinated dioxin congeners, based on their aryl hydrocarbon receptor (AhR)-mediated mode of toxic action. Transactivation of the AhR was measured using dioxin-responsive (DR) CALUX reporter gene assays. Because of known species-differences in dioxin-mediated toxicity, we developed and used a HepG2 human liver cell-based DR human CALUX assay that is a variant of the rodent-based DR CALUX. The assay was found to be highly inducible and stable, with low variations between independent measurements. Using both DR CALUX assays in an automated high-throughput mode we found that overall PBDD/Fs were as potent as PCDD/Fs in inducing AhR transactivation, but congener-specific differences were observed. We also observed species-specific differences in sensitivity and potency when comparing DR human REP values to those obtained in the rat-based DR CALUX. Finally, we observed significant differences between WHO-TEF values and DR human REP values, suggesting that actual WHO-TEF values may underestimate the hazards associated with exposure of humans to dioxins.

Detection of high PBDD/Fs levels and dioxin-like activity in toys using a combination of GC-HRMS, rat-based and human-based DR CALUX® reporter gene assays

Brominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) are increasingly reported at significant levels in various matrices, including consumer goods that are manufactured from plastics containing certain brominated flame retardants. PBDD/Fs are known ligands for the aryl hydrocarbon receptor (AhR) but are not yet considered in the hazard assessment of dioxin mixtures. The aim of the present study was to determine if PBDD/Fs levels present in plastic constituents of toys could pose a threat to children's health. PBDD/Fs, unlike their chlorinated counterparts (PCDD/Fs), have not been officially assigned toxic equivalence factors (TEFs) by the WHO therefore, we determined their relative potency towards AhR activation in both human and rodent cell-based DR CALUX® bioassays. This allowed us to compare GC-HRMS PBDD/F congener levels, converted to total Toxic Equivalents (TEQ) by using the PCDD/F TEFs, to CALUX Bioanalytical Equivalents (BEQ) levels present in contaminated plastic constituents from children's toys. Finally, an estimate was made of the daily ingestion of TEQs from PBDD/Fs-contaminated plastic toys by child mouthing habits. It is observed that the daily ingestion of PBDD/Fs from contaminated plastic toys may significantly contribute to the total dioxin daily intake of young children.

[Neurologic signs revealing a Behçet's disease: two pediatric case reports]

Behçet's disease can be revealed by neurologic signs.

CASE REPORTS

We report two pediatric cases of Behçet's disease which initially presented with cerebral venous thrombosis. Glucocorticoïds, associated with anticoagulant treatment allowed a rapid recovery. One of the children presented three years later a thrombotic recurrence.

CONCLUSION

A cerebral venous thrombosis may reveal Behçet's disease.

Category and modality specific dissociations in word comprehension and concurrent phonological dyslexia

A 62-yr-old aphasic patient was found to have a marked auditory comprehension deficit for body parts, colors, numbers and letters in the face of excellent comprehension for all other word categories and virtually intact reading comprehension for all word categories, including those affected by the auditory dissociation. A severe impairment in the graphophonemic route for reading was also discovered. The case is discussed in the context of category-specific dissociations after brain injury and the possible mechanism for failures of body part comprehension.