Objective To develop an isotope dilution liquid chromatography tandem mass spectrometry (ID-LC-MS/MS) method for determining the concentration of 5-methyltertrahydrofolate (5MT) in human serum.Methods After qualitative analysis of 5MT reference,its purity was identified by two methods with different principle,i.e.,mass balance and quantitative nuclear magnetic resonance.The definite value and uncertainty of 5MT concentrations in 6 serum samples containing same level of 5MT were assessed by ultra performance liquid chromatography-triple quadrupole tandem mass spectrometer equipped with electrospray ionization in monitoring mode of multiple reactions,in which 13C5-5MT was used as the internal standard.The precision,accuracy,limit of detection (LOD) and limit of quantification (LOQ) of the method were also evaluated.Results After qualitative analysis for confirming the principal component in the sample,the purity of 5MT reference was measured as 76.65％ by mass balance and quantitative nuclear magnetic resonance method.The definite value of 5MT in the serum sample was 8.22 ng/mL,the extended uncertainty was 0.54 ng/mL,LOD was 0.05 ng/mL,LOQ was 0.50 ng/mL and the repeatability and inter-batch precision CV were within 5.0％.The accuracy of measured results was verified by using NIST SRM 1955 since all the values of 3 levels were within the range of certified value with the extended uncertainty.Conclusion A accurately quantitative determination for the concentration of 5 MT in human serum with high specificity and sensitivity was established by using ID-LC-MS/MS method.

OBJECTIVETo clarify the natural course and explore impact factors of distant metastasis in rectal cancer patients who received total mesorectal excision(TME) following neoadjuvant chemoradiotherapy (CRT).

METHODSBetween Januray 2008 and December 2013, 317 patients with locally advanced rectal cancer who underwent radical surgical resection following neoadjuvant CRT (pre- and postoperative simple fluorouracil or fluorouracil combined with oxaliplatin plus preoperative three dimensional conformal radiotherapy) at Department of Colorectal Surgery in Fujian Medical University Union Hospital were included. Univariate analysis and Cox regression were performed to evaluate the clinicopathological parameters that may be associated with distant metastasis.

RESULTSDuring a median follow-up of 39 months(range 15 - 89 months), 72 patients(22.7%) had disease recurrence, including local recurrence in 8 patients, and distant metastasis in 67 patients (among whom 3 patients had both). Distant metastasis occurred in 86.5%(58/67) patients during the first three years after surgery. The 3-year cumulative distant metastatic rate in all the patients was 22.4%. The 5-year overall survival rate in distant metastatic patient was significantly lower than that of non-distant metastatic patients following neoadjuvant CRT (36.2% vs. 81.2%, P=0.000). Univariate analysis showed that ypT stage (χ(2)=13.304, P=0.010), ypN stage(χ(2)=23.416, P=0.000), ypTNM stage (χ(2)=31.765, P=0.000) and RCRG(χ(2)=16.246, P=0.000) were associated with distant metastasis. Cox regression revealed that ypTNM stage(HR=1.959, 95% CI:1.171 ~ 3.277, P=0.010) was the only independent risk factor of distant metastasis.

CONCLUSIONSDistant metastasis is the early event during the progression in rectal cancer. ypTNM stage is the only independent risk factor of distant metastasis in locally advanced rectal cancer patients who undergo TME following neoadjuvant CRT.

Chemoradiotherapy ; Digestive System Surgical Procedures ; Fluorouracil ; therapeutic use ; Humans ; Neoadjuvant Therapy ; Neoplasm Metastasis ; Neoplasm Recurrence, Local ; Neoplasm Staging ; Organoplatinum Compounds ; therapeutic use ; Rectal Neoplasms ; drug therapy ; pathology ; surgery ; Risk Factors ; Survival Rate

GGGGCC repeat expansions in the C9ORF72 gene are the most common cause of amyotrophic lateral sclerosis and frontotemporal dementia (c9ALS/FTD). It has been reported that hexanucleotide repeat expansions in C9ORF72 produce five dipeptide repeat (DPR) proteins by an unconventional repeat-associated non-ATG (RAN) translation. Within the five DPR proteins, poly-PR and poly-GR that contain arginine are more toxic than the other DPRs (poly-GA, poly-GP, and poly-PA). Here, we demonstrated that poly-PR peptides transferred into cells by endocytosis in a clathrin-dependent manner, leading to endoplasmic reticulum stress and cell death. In SH-SY5Y cells and primary cortical neurons, poly-PR activated JUN amino-terminal kinase (JNK) and increased the levels of p53 and Bax. The uptake of poly-PR peptides by cells was significantly inhibited by knockdown of clathrin or by chlorpromazine, an inhibitor that blocks clathrin-mediated endocytosis. Inhibition of clathrin-dependent endocytosis by chlorpromazine significantly blocked the transfer of poly-PR peptides into cells, and attenuated poly-PR-induced JNK activation and cell death. Our data revealed that the uptake of poly-PR undergoes clathrin-dependent endocytosis and blockade of this process prevents the toxic effects of synthetic poly-PR peptides.