Evaluation of Antibacterial and Cytotoxicity Properties of Silver Nanowires and Their Composites with Carbon Nanotubes for Biomedical Applications

In this work, we prepared silver nanowires (AgNWs) via the polyol method in the presence or absence of single wall carbon nanotubes (CNTs) and tested their physicochemical, antibacterial and cytotoxic properties. Results showed that the introduction of CNTs lead to the formation of AgNWs at lower temperature, but the final product characteristics of AgNWs and AgNWs-CNT were not significantly different. AgNWs exhibited antibacterial properties against all the studied bacterial species via the formation of oxygen reactive species (ROS) and membrane damage. Furthermore, AgNWs exhibited a dose-dependent and time-dependent toxicity at concentrations ≥ 10 µg/mL. Fibroblasts appeared to be more resistant than human colorectal adenocarcinoma (Caco-2) and osteoblasts to the toxicity of AgNWs. The cytotoxicity of AgNWs was found to be related to the formation of ROS, but not to membrane damage. Overall, these results suggest that AgNWs are potential antibacterial agents against E. coli, S. aureus, MRSA and S. saprophyticus, but their dosage needs to be adjusted according to the route of administration.

Adenoma, advanced adenoma and colorectal cancer prevalence in asymptomatic 40- to 49-year-old subjects with a first-degree family history of colorectal cancer

AIM

First-degree relatives (FDRs) of patients with colorectal cancer (CRC) have an increased CRC risk. Few studies have addressed if adenoma and advanced adenoma risk is increased among individuals, 40-49 years of age, with a family history of CRC. Therefore, the aim of the study was to define the prevalence and location of adenoma, advanced adenoma and CRC, according to age, in asymptomatic individuals with a family history of CRC.

METHOD

Retrospective study of asymptomatic FDRs, 40 to ≥70 years of age undergoing first screening colonoscopy over a 3-year period, of CRC patients.

RESULTS

Among 464 individuals studied, the prevalence of adenoma and advanced adenoma was 18.1% and 6.4%, respectively. According to age intervals, the prevalences of adenoma and advanced adenoma were 14% and 3.5%, respectively, in subjects 40-49 years of age; 14.4% and 6.3%, respectively, in subjects 50-59 years of age; 27% and 8%, respectively, in subjects 60-69 years of age; and 25% and 14%, respectively, in subjects ≥70 years of age; no significant difference was found among the four groups. No difference in lesion location was found, with similar numbers of preneoplastic lesions being present in the right colon and the left colon. CRC was diagnosed in three (0.64%) subjects, one of whom was in the 40-49 years age group.

CONCLUSION

In our population of FDRs of CRC patients, 40-49 years of age, the prevalences of adenoma and advanced adenoma were similar to those observed in older subjects with the same CRC risk. Our data support the current indication to perform screening colonoscopy earlier than 45 years of age in subjects at high CRC risk.

Epigenetically silenced miR-34b/c as a novel faecal-based screening marker for colorectal cancer

BACKGROUND

MicroRNAs are tiny non-coding small endogenous RNAs that regulate gene expression by translational repression, mRNA cleavage and mRNA inhibition. The aim of this study was to investigate the hypermethylation of miR-34b/c and miR-148a in colorectal cancer, and correlate this data to clinicopathological features. We also aimed to evaluate the hypermethylation of miR-34b/c in faeces specimens as a novel non-invasive faecal-DNA-based screening marker.

METHODS

The 5-aza-2'-deoxycytidine treatment and methylation-specific PCR were carried out to detect the hypermethylation of miR-34b/c and miR-148a.

RESULTS

The miR-34b/c hypermethylation was found in 97.5% (79 out of 82) of primary colorectal tumours, P=0.0110. In 75% (21 out of 28) of faecal specimens we found a hypermethylation of miR-34b/c while only in 16% (2 out of 12) of high-grade dysplasia. In addition, miR-148a was found to be hypermethylated in 65% (51 out of 78) of colorectal tumour tissues with no significant correlation to clinicopathological features. However, a trend with female gender and advanced age was found, P=0.083. We also observed a trend to lower survival rate in patients with miR-148a hypermethylation with 10-year survival probability: 48 vs 65%, P=0.561.

CONCLUSIONS

These findings show that aberrant hypermethylation of miR-34b/c could be an ideal class of early screening marker, whereas miR-148a could serve as a disease progression follow-up marker.