Antimicrobial resistance in E. Coli of animal origin and discovery of a novel ICE mobile element in Northeast China.

BACKGROUND: Multidrug resistance in Enterobacteriaceae including resistance to quinolones is rising worldwide. The development of resistance may lead to the emergence of new transmission mechanisms. In this study, the collection of different E. coli was performed from animals and subjected to subsequent procedures including pulsed-field gel electrophoresis, micro-broth dilution method, polymerase chain reaction. Whole genome sequencing of E. coli C3 was performed to detect the affinity, antimicrobial resistance and major carriers of the isolates. RESULTS: A total of 66 E. coli were isolated and their antibiotic resistance genes, frequency of horizontal transfer and genetic environment of E. coli C3 were determined. The results showed there were both different and same types in PFGE typing, indicating clonal transmission of E. coli among different animals. The detection of antimicrobial resistance and major antibiotic resistance genes and the plasmid transfer results showed that strains from different sources had high levels of resistance to commonly used clinical antibiotics and could be spread horizontally. Whole-genome sequencing discovered a novel ICE mobile element. CONCLUSION: In summary, the antimicrobial resistance of E. coli in northeast China is a serious issue and there is a risk of antimicrobial resistance transmission. Meanwhile, a novel ICE mobile element appeared in the process of antimicrobial resistance formation.

Genetic characterization of MDR genomic elements carrying two aac(6')-aph(2″) genes in feline-derived clinical Enterococcus faecalis isolate.

Multidrug-resistant Enterococcus faecalis (E. faecalis) often cause intestinal infections in cats. The aim of this study was to investigate a multidrug-resistant E. faecalis isolate for plasmidic and chromosomal antimicrobial resistance and their genetic environment. E. faecalis strain ESC1 was obtained from the feces of a cat. Antimicrobial susceptibility testing was carried out using the broth microdilution method. Conjugation experiments were performed using Escherichia coli and Staphylococcus aureus as receptors. Complete sequences of chromosomal DNA and plasmids were generated by whole genome sequencing (WGS) and bioinformatics analysis for the presence of drug resistance genes and mobile elements. Multidrug-resistant E. faecalis ESC1 contained a chromosome and three plasmids. The amino acid at position 80 of the parC gene on the chromosome was mutated from serine to isoleucine, and hence the amino acid mutation at this site led to the resistance of ESC1 strain to fluoroquinolones. Eleven antibiotic resistance genes were located on two plasmids. We identified a novel composite transposon carrying two aminoglycoside resistance genes aac(6')-aph(2″). This study reported the coexistence of a novel 5.4 kb composite transposon and a resistance plasmid with multiple homologous recombination in an isolate of E. faecalis ESC1. This data provides a basis for understanding the genomic signature and antimicrobial resistance mechanisms of this pathogen.

Biodegradable Biomaterial Arterial Stent in the Treatment of Coronary Heart Disease.

This study aims to evaluate the clinical application value of two materials, drug-eluting stent, and biodegradable stent, in the treatment of coronary heart disease. The results show that the therapeutic effects of drug-eluting stents and biodegradable stents are similar. Both treatment methods have high safety and effectiveness. The ideal coronary artery stent should have good biocompatibility, safety, and possibility.

Nobiletin potentiates paclitaxel anticancer efficacy in A549/T xenograft model: Pharmacokinetic and pharmacological study.

BACKGROUND: Nobiletin (N), a polymethoxylated flavone from citrus fruits, enhanced anti-cancer effects of paclitaxel (PTX) in multi-drug resistance (MDR) cancer cells via inhibiting P-glycoprotein (P-gp) in our previous report. But the in vivo chemo-sensitizing effect of nobiletin is unknown. Moreover, considering the nonlinear pharmacokinetics and narrow therapeutic window of PTX, drug-drug interaction should be explored for using nobiletin with PTX together. PURPOSE: In this study, we wanted to explore whether nobiletin could affect the pharmacokinetic (PK) behavior of PTX and reverse drug resistance in vivo as well as the corresponding mechanisms. STUDY DESIGN AND METHODS: Accurate and sensitive UPLC-MS/MS method was developed for the detection of PTX, and was applied to the pharmacokinetic study in rats. In vivo anti-MDR tumor study was carried out with A549/T xenograft nude mice model. Immunohistochemistry and western blot analysis were used for evaluating the levels of P-gp, Nrf2, and AKT/ERK pathways in MDR tumors. RESULTS: Nobiletin significantly enhanced the therapeutic effects of PTX, and inhibited the MDR tumor sizes in the A549/T xenograft model, while PTX or nobiletin alone did not. We found that nobiletin increased the PTX concentrations in tumor tissues but did not affect the PK behavior of PTX. Notably, Nrf2 and phosphorylation of AKT/ERK expression in MDR tumor tissues were significantly inhibited by giving nobiletin and PTX together. However, nobiletin did not affect the expression of P-gp. CONCLUSION: Nobiletin reversed PTX resistance in MDR tumor via increasing the PTX content in the MDR tumor and inhibiting AKT/ERK/Nrf2 pathways, but without affecting the systematic exposure of PTX, indicating that nobiletin may be an effective and safe MDR tumor reversal agent.

Baicalein Enhances the Oral Bioavailability and Hepatoprotective Effects of Silybin Through the Inhibition of Efflux Transporters BCRP and MRP2.

Although hepatoprotective properties of silybin are well documented, the clinical therapeutic efficacy is limited by its low bioavailability due to absorption rates, extensive phase II metabolism, and biliary excretion. As our previous study indicated that metabolic enzymes may have limited effects on the pharmacokinetic (PK) behavior of silymarin, here, we intended to increase the oral bioavailability and bio-efficacy of silybin through the inhibition of active efflux. In Caco-2 and transfected MDCKII cell models, flavone baicalein significantly inhibited the efflux of silybin as a BCRP and MRP2 inhibitor. In addition, baicalein reduced the biliary excretion index (BEI) and biliary clearance of silybin conjugates in the sandwich-cultured rat hepatocyte (SCH) model, indicating the inhibition of baicalein in biliary excretion of conjugated silybin metabolites. PK study demonstrated that baicalein significantly increased the area under the curve (AUC) and Cmax of silybin and its conjugates, suggesting enhanced absorption in vivo. Moreover, coadministration of silybin with baicalein boosted the liver protective, antioxidant, and anti-inflammatory effects of silybin in the carbon tetrachloride (CCl4)-induced liver injury model in comparison with silybin given alone. In summary, efflux transporters play a critical role in the low bioavailability of silybin, while inhibition of breast cancer resistance protein (BCRP) and multi-drug resistance protein 2 (MRP2) by baicalein can significantly increase the absorption and bio-efficacy of silybin, which provides a new combination therapeutic approach for the treatment of chronic liver diseases.

Role of tangeretin as a potential bioavailability enhancer for silybin: Pharmacokinetic and pharmacological studies.

Biological responses of a variety of naturally occurring compounds in vivo were restrained by their poor oral bioavailability. Silybin, as one of the active ingredients of silymarin, has presented promising bioactivity for the treatment of chronic liver diseases and cancer. However, its exposure in body was limited. In this study, silybin was demonstrated to be substrates of both BCRP and MRP2 by utilizing monolayer Caco-2 cell model and confirmed in MDCK cells overexpressing specific efflux transporter. Of all compounds screened, tangeretin, a potent inhibitor of efflux transporters of BCRP, MRP2 and P-gp, was able to enhance exposure of silybin by inhibiting functions of the barriers mediating transcellular transport. Moreover, study carried out in sandwich-cultured rat hepatocyte (SCH) model showed that the biliary excretion index (BEI) and in vitro biliary clearance of silybin decreased as levels of tangeretin increased, indicating efflux transporters mediating biliary excretion of silybin might be involved. Pharmacokinetic behaviors of silybin in rats were altered by co-administration of tangeretin, in terms of increased AUC and Cmax of silybin by comparing with that of silybin given alone. In addition, results coming from CCl4-induced acute liver injury rat model revealed that protection effect of silybin against liver damage in the presence of tangeretin was significantly enhanced. All these data were evident that efflux transporters play a critical role in transcellular transport of silybin and account for its low bioavailability. Enhanced bioavailability of silybin with co-administration of tangeretin by significantly inhibiting the efflux transporters further boost its bioactivity which is of particular importance in clinical use.

The Targeted-liposome Delivery System of Antitumor Drugs.

The liposome delivery system has been intensively explored as novel drug delivery system (DDS) for antitumor drugs, due to its safety, selective cytotoxicity, long circulation and slow elimination in blood, which is favorable for cancer therapy. The liposome-based chemotherapeutics are used to treat a variety of cancers to enhance the therapeutic index of antitumor drugs. Here, the author reviewed the important targets for cancer therapy and the pharmacokinetic behavior of liposomal drugs in vivo, as well as the application of the targeting liposomal system in cancer therapy. Considering further application for clinical use, the great challenges of the liposome-based delivery system were also proposed as follows: 1) prepare stealth liposome with steric stabilization and further enhance the therapeutic effects and safety; 2) explore more safe clinical targets and complementary or different types of targeting liposome; 3) thirdly, more investment is needed on the research of pharmacokinetics of the elements such as the ligands (antibody), PEG and lipids of liposome delivery system as well as safety evaluation. Considering the complex process of the liposomal encapsulation drugs in vivo, the author inferred that there are maybe different forms of the encapsulation drug to be internalized by the tumor tissues at the same time and space, although there are little reports on it.

Drug metabolism and pharmacokinetics of nanodrugs from Chinese medicines and natural products.

Over the past few years, nanoscale Chinese medicine has become one of focuses in modern Chinese medicine research. There is an increasing need for a more systematic study on the basic issues involved in traditional Chinese medicine and a more active participation of researchers in the application area of nanoscale traditional Chinese drugs. In this review, author analyzed the current applications of nanotechnology in research and development of drugs from natural products and herbal medicines involving traditional Chinese medicines, and also discussed the bio-medicinal evaluation issues on ADME including bio-distribution and metabolism of nanodrugs. Author noted that great challenges faced in nanodrugs from herb drugs and natural products are the follows: (1) the first challenge is to prepare nanodrug delivery system and quantitatively evaluate the therapeutic effects and safety; (2) the second challenge is to clarify the concrete metabolism course; and (3) the third challenge is to study the pharmacokinetics of nanodrugs.

Herb-drug interactions involving drug metabolizing enzymes and transporters.

Herbal medicines and their active ingredients are widely used worldwide, and they have become an important part of clinical medicine. The combined use of herbs and drugs has increased the possibility of pharmacokinetic and pharmacodynamic interactions. Clinical studies have demonstrated that the combined use of herbs and drugs can enhance or attenuate the drug efficacy and toxicity. The herb-drug combinations may reduce a drug efficacy and lead to treatment failure when long-term administration. Case reports detailing serious clinical adverse reactions have promoted studies on the interactions between herbs and drugs. This review highlights recent knowledge to discuss herb-drug interactions involving metabolizing enzymes and drug transporters. Drug transporters are widely present in body and play an important role in the absorption, distribution, excretion and metabolism, efficacy, and toxicity of drugs. Investigation of transporters has developed rapidly since 1990s, the effects of many transporters on the pharmacokinetics of drugs and herb-drug interactions have been reported. Some concepts on drug transporters issued experimentally and clinically drug-drug and herb-drug interactions have applied in many studies. Methodology studies are very important for understanding the mechanism, considerations and evaluation of experiments and clinical studies on drug metabolizing enzymes and transporters in drug-drug interactions.

Clinicopathological significance of LRP16 protein in 336 gastric carcinoma patients.

AIM: To investigate the expression of leukemia related protein 16 (LRP16), and the possible relationship between LRP16 expression and clinicopathological indices in 336 gastric carcinoma patients. METHODS: Immunohistochemistry was used to detect LRP16 expression in 336 cases of paraffin-embedded gastric carcinoma tissues and 60 cases of distal normal mucosa. The relationships between LRP16 expression and patients' age, tumor size, histological grade, clinical stage, metastatic status and prognosis were analysed. RESULTS: The expression of LRP16 was 58.6% (197/336) in gastric carcinoma and 31.7% (19/60) in distal normal gastric mucosa. The expression of LRP16 in carcinoma was significantly higher than that in normal mucosa tissues (chi(2) = 14.929, P = 0.001). LRP16 protein expression was found in 44.1% (63/143) carcinomas at stage I and II, and 69.4% (134/193) carcinomas at stage III and IV (chi(2) = 21.804, P = 0.001), and in 56.9% (182/320) of cancers without metastasis but 93.8% (15/16) of those with metastasis (chi(2) = 8.543, P = 0.003). The expression of LRP16 was correlated with tumor size, infiltrative depth, clinical stage, lymphatic invasion and distant metastasis (all P < 0.05). Follow-up data showed that there was a significant difference in median survival time between cancer patients with expression of LRP16 (27.0 mo) and those without (48.0 mo, Log rank =31.644, P = 0.001). CONCLUSION: The expression of LRP16 may be associated with invasion, metastasis and prognosis of gastric cancer.

[Expressions of cyclinB1, FHIT and Ki-67 in 336 gastric carcinoma patients and their clinicopathologic significance].

OBJECTIVE: To investigate the expressions of cyclinB1, FHIT and Ki-67 in gastric carcinoma and their clinical significance. METHODS: Immunohistochemistry (PV6000 method) was used to detect the expressions of cyclinB1, FHIT and Ki-67 in paraffin-embedded gastric carcinoma tissues of 336 cases and paracancerous normal mucosa of 60 cases. All cases were successfully followed up. RESULTS: The positive expression rates of cyclinB1, FHIT and Ki-67 in gastric carcinoma were 66.1% (222/336), 39.9% (134/336) and 58.3% (196/336) respectively. CyclinB1 and Ki-67 were all correlated with tumor size, differentiation degree, infiltrative depth, clinical stage, lymphatic invasion and distant metastasis (P < 0.05). And FHIT showed a correlation with differentiation degree, lymphatic invasion and clinical stage (P < 0.05). The 5-year survival rate of patients with positive cyclinB1 and Ki-67 expressions were both lower than those with negative expressions (P < 0.05), whereas FHIT had the opposite pattern (P = 0.025). The cyclinB1 expression in gastric carcinoma was positively correlated with the Ki-67 expression (r = 0.249, P = 0.0001). The expressions of cyclinB1 and Ki-67 in carcinoma were significantly higher than those in normal mucosa tissues (P < 0.05), but FHIT had the opposite pattern. Ki-67 was an independent prognostic indicator for post-operative survival time. CONCLUSION: CyclinB1, FHIT and Ki-67 may play significant roles in the occurrence and evolution of gastric carcinoma. And they can be used as useful indicators for clinical assessment of tumor biological behaviors and prognosis in patients with gastric carcinoma.

[Clinicopathological significance of expressions of DNA dependent protein kinase catalytic subunit and P16 in colorectal carcinoma].

OBJECTIVE: To investigate the expression of DNA dependent protein kinase catalytic subunit (DNA-PKcs) and P16 (multiple tumor suppressor 1) genes in colorectal carcinoma and clinical significance thereof. METHODS: 359 specimens of colorectal carcinoma obtained during operation and 35 specimens of normal mucosa beside the carcinoma underwent immunohistochemical examination and Western blotting to detect the expression of DNA-PKcs and P16. RESULTS: The positive expression rates of DNA-PKcs and P16 of the colorectal carcinoma specimens were 63.5% (228/359) and 53.2% (191/359) respectively, both significantly higher than those of the para-cancer normal tissues (both P < 0.05). DNA-PKcs and P16 expression were both related to the clinical stage, lymphatic invasion, and distant metastasis (all P < 0.05). The 5-year survival rates of the patients positive in DNA-PKcs and P16 expression were significantly lower than those of the patients negative in DNA-PKcs and P16 expression (both P < 0.05). The DNA-PKcs positive rate of the P16-positive patients was 78.6%, significantly higher than that of the P16-negative patients (55.3%, r = 0.149, P = 0.036). CONCLUSION: DNA-PKcs and P16 play a significant role in the carcinogenesis and evolution of colorectal carcinoma and may be used as one of the useful indicators for clinical assessment of tumor biological behavior and prognosis of colorectal carcinoma.