Adsorption-desorption behaviors of ciprofloxacin onto aged polystyrene fragments in aquatic environments.

As two emerging pollutants of great concern, microplastics (MPs) and antibiotics inevitably cooccur in various aquatic environments and interact with each other, impacting the fate and ecological risks. Aging obviously complicates their interaction and deserves further study. Therefore, the adsorption-desorption behaviors of ciprofloxacin (CIP) onto polystyrene (PS) fragments with various aging extent were investigated, and the key physiochemical properties influencing the interaction and the interaction mechanisms were clarified by redundancy analysis, FTIR and XPS spectra. The physicochemical properties of PS MPs were significantly changed with aging time, and the morphological and chemical changes seemed to occur asynchronously. The adsorption of CIP onto the pristine PS MPs relied on physisorption, especially the ion-involving electrostatic and cation-π interaction. Due to the hydrogen bonding formed by the C-OH, CO, and O-CO groups of PS and CIP, the adsorption capacities of the aged PS MPs were greatly increased. The desorption efficiency of CIP from MPs in the gastric fluid was closely related to the solution ionic strengths, C-OH and CO groups of MPs, while that in the intestinal fluid was associated with O-CO groups of MPs. The different impact factors could be well described by the differences in the chemical components and pHs of the simulated gastric and intestinal fluids. This study gives a comprehensive understanding of the adsorption-desorption behaviors of antibiotics onto MPs at a molecular level and indicates that MPs could act as Trojan horses to transport antibiotics into aquatic organisms.

[Mutation analysis of LITAF, RAB7, LMNA and MTMR2 genes in Chinese Charcot-Marie-Tooth disease.].

The purpose of this study was to understand the mutation features of lipopolysaccharide-induced tumor necrosis factor-alpha factor (LITAF), ras-associated protein RAB7 (RAB7), lamin A/C (LMNA) and myotubularin-related protein 2 (MTMR2) genes in Chinese Charcot-Marie-Tooth disease (CMT) patients. Mutation analysis of LITAF gene was carried out using PCR combined with DNA sequencing, and mutation analysis of RAB7 gene by PCR-single strand conformation polymorphism (PCR-SSCP) combined with DNA sequencing in 33 CMT patients including 6 probands of autosomal domi-nated CMT families and 27 sporadic patients; mutation analysis of LMNA and MTMR2 genes was observed using PCR-SSCP combined with DNA sequencing in 41 CMT patients, including 14 probands of autosomal recessive CMT fami-lies and 27 sporadic patients. Two sequence variations c.269G-->A and c.274A-->G were detected in LITAF gene and two sequence variations c.1243G-->A and c.1910C-->T were detected in LMNA gene. No sequence variation was found in RAB7 and MTMR2 gene. Variations of c.269G-->A in LITAF gene and c.1243G-->A, c.1910C-->T in LMNA gene are newly found SNPs in this study. Variation of c.274A-->G in LITAF gene is known SNP reported in SNP database. Mutations in LITAF, RAB7, LMNA, and MTMR2 genes are rare in Chinese CMT patients.