Young people exposure to antibiotics: Implication for health risk and the impact from eating habits of takeaway food

Exposure to antibiotics, mainly from animal food ingestion, may have adverse effects on human health. Takeaway food is the preferred choice for the dietary of most Chinese young people nowadays, but the relationship between takeaway eating and antibiotic exposure is not yet adequately understood. In the present study, 297 young people were recruited to collect urine samples and questionnaires with an emphasis on their takeaway eating habits. The internal exposure to 16 antibiotics and three metabolites was measured in urine samples by high-performance liquid chromatography-tandem mass spectrometry, as well as a DNA oxidative damage marker, 8-hydroxydeoxyguanosine (8-OHdG). At least one kind of antibiotic was found in over 90 % of urine samples, with total concentrations from 0.667 to 3.02 × 104 ng/mL. High exposure levels of antibiotics were more likely to be found in individuals with a larger body mass index. The concentrations of six antibiotics were significantly different among people with different overall weekly eating frequencies, usually an upward trend. The estimated daily intakes of antibiotics were on the levels of 0.001-1.0 μg/kg/day, mainly contributed by clarithromycin, ciprofloxacin and oxytetracycline, indicating a potential health risk based on the microbiological effect. A significantly positive correlation was found between DNA oxidative damage and exposure for four categories of antibiotics, conformed by both Spearman correlation and multiple linear regression analysis. The levels of 8-OHdG were 355 %, 239 %, 234 %, and 334 % higher with elevated levels of phenicols, macrolides, tetracyclines and sulfonamides from quartiles 2 to 4. Our results suggest that high-frequency consumption of takeaways may exacerbate oxidative stress trends through human exposure to antibiotics.

Underlying Degradation of Phthalates via Microbials in Dust from Different Microenvironments

Phthalate monoesters (me-PAEs) have been used as biomarkers for assessing human exposure to phthalate esters (PAEs) for a long time, and studies on the sources and distribution of me-PAEs in the environment are limited. In this study, dust samples from microenvironments were collected to measure the occurrence of PAEs and me-PAEs, as well as the bacterial diversity. The results indicated that me-PAEs coexisted with PAEs in different microenvironmental dust samples, with concentrations of nine PAEs and 16 me-PAEs ranging from 108 to 1450 μg/g (median range) and 6.00 to 21.6 μg/g, respectively. The concentrations of several low molecular weight me-PAEs (e.g., monomethyl phthalate and monoethyl phthalate) in dust were even significantly higher than those of their parents. The bacteria in the dust were mainly predominant with Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes (total abundance >90%). Bacteria from bus and air conditioning dust samples had the highest species richness and species diversity. Seven genes of suspected enzymes with the ability to degrade PAEs were selected, and the concentration of me-PAEs increased with increasing abundance of enzyme function. Our findings will provide useful information on the profiles of me-PAEs and their potential sources in indoor dusts, which will benefit the accurate estimation of human exposure.

Drug-resistance reversal in colorectal cancer cells by destruction of flotillins, the key lipid rafts proteins

Multi-drug resistance (MDR) of tumor cells attenuates the efficacy of anticancer drugs and has become the main reason for chemotherapy failure. It is indispensable to establish an effective way to reverse multi-drug resistance. Our previous work has shown that down-regulation of the ERK/MAPK signaling pathway activity can reverse the drug-resistance of resistant cells. Further-more, the effect of signal transduction is strongly associated with lipid rafts. The drug-resistance is reversed successfully after lipid rafts are destroyed by heptakis(2, 6-di-O-methyl)-β-cyclodextrin (MβCD). However, the reversal of the drug-resistance is not associated with down-regulation of the expression of ERK1/2. Cell membrane permeability may increase when lipid rafts are destroyed by MβCD, causing the reversal of drug-resistance due to an increase in accumulation of the drugs in the cytoplasm. To minimize the influence of MβCD on the cell membrane structure, we selected flotillin, a marker protein of lipid rafts, as the target molecule, to further investigate the mechanism of changes in drug resistance after destruction of the lipid rafts. The effect of flotillin on the reversal of the drug resistance was examined using an RNA interference (RNAi) in a retrovirus system in human drug-resistant strains of colorectal cancer cell line HCT-15. The results demonstrate that flotillin-1 downregulation by RNAi (Flot1-RNAi) reduced the drug resistance, caused cell cycle arrest and decreased the expression of ERK1/2; however, apoptosis was not significantly affected. Knockdown of flotillin-2 by RNAi (Flot2-RNAi) had effects similar to those of Flot1-RNAi except that the effects on expression of ERK1/2 and apoptosis were different. Screening of multiple pathways indicated that the PI3K/Akt signaling pathway was closely related. This experiment demonstrates the association between PI3K and drug resistance through the activation of PI3K and suggests that PI3K may play a key role during the development of resistance in CRC. The results reveal that the levels of IRS-1 and PI3K proteins in the Flot1-RNAi and Flot2-RNAi groups were significantly down-regulated. Knockdown of flotillins by RNAi reduced the resistance of HCT-15/ADM cells; the results investigations of the Akt pathway indicate a decrease in resistance after lipid raft destruction. These data confirm that knockdown of flotillin reduces the resistance of HCT-15/ADM cells, and the mechanism may be relevant to the PI3K/Akt pathway. Additionally, flotillin may be used as a potential target for chemotherapy in the treatment of colorectal cancer.

Modulatory effects of taurine on jejunal contractility

Taurine (2-aminoethanesulfonic acid) is widely distributed in animal tissues and has diverse pharmacological effects. However, the role of taurine in modulating smooth muscle contractility is still controversial. We propose that taurine (5-80 mM) can exert bidirectional modulation on the contractility of isolated rat jejunal segments. Different low and high contractile states were induced in isolated jejunal segments of rats to observe the effects of taurine and the associated mechanisms. Taurine induced stimulatory effects on the contractility of isolated rat jejunal segments at 3 different low contractile states, and inhibitory effects at 3 different high contractile states. Bidirectional modulation was not observed in the presence of verapamil or tetrodotoxin, suggesting that taurine-induced bidirectional modulation is Ca²⁺ dependent and requires the presence of the enteric nervous system. The stimulatory effects of taurine on the contractility of isolated jejunal segments was blocked by atropine but not by diphenhydramine or by cimetidine, suggesting that muscarinic-linked activation was involved in the stimulatory effects when isolated jejunal segments were in a low contractile state. The inhibitory effects of taurine on the contractility of isolated jejunal segments were blocked by propranolol and L-NG-nitroarginine but not by phentolamine, suggesting that adrenergic β receptors and a nitric oxide relaxing mechanism were involved when isolated jejunal segments were in high contractile states. No bidirectional effects of taurine on myosin phosphorylation were observed. The contractile states of jejunal segments determine taurine-induced stimulatory or inhibitory effects, which are associated with muscarinic receptors and adrenergic β receptors, and a nitric oxide associated relaxing mechanism.