Epitaxial growth of boron-doped graphene by thermal decomposition of B4C

We grew graphene by thermal decomposition of B(4)C and investigated its features by high-resolution transmission electron microscope observations. At temperatures higher than 1600 °C in a vacuum, B(4)C decomposes and graphene forms epitaxially on its surface. The number and the morphology of the graphene layers depend on the surface orientation. An electron diffraction technique revealed the presence of a superstructure with a two-times larger unit cell, which is consistent with the structure of BC(3). We have directly confirmed boron in the graphene layers by electron energy loss spectroscopy measurements and boron-mapping experiments.

Evaluation of serum CXCL5 as a serum marker for prognosis of colorectal cancer patients

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Background: CXCL5 is known as CXC chemokine which promotes angiogenesis related to cancer. However, the function of serum level of CXCL5 (sCXCL5) has not been fully studied in colorectal cancer. The purpose of this study was to evaluate the relationships between preoperative sCXCL5 and clinicopathological features and prognosis in colorectal cancer.

Methods: This was a single-institution, retrospective study. Preoperative serum samples of 250 colorectal cancer patients (between 1998 and 2007, median age: 65.3 years, male 159/female 91) were available for the study, and 33 normal serum was examined and used as a control. sCXCL5 level was assayed using a commercially available enzyme-linked immunosorbent assay kit, and analyzed statistically.

Results: Mean level of sCXCL5 was significantly higher in colorectal cancer patients than in control group (p=0.013). Patients with liver metastases had significantly higher sCXCL5 level than those without metastases (p=0.0086), and in logistic analysis, sCXCL5 was an independent marker for predicting liver metastasis (p=0.040). Overall survival of patients with elevated sCXCL5 level was significantly worse than those with lower sCXCL5 (p=0.0006).

Conclusions: Preoperative sCXCL5 level was increased in colorectal cancer patients compared to in healthy volunteer and elevated sCXCL5 was correlated with liver metastasis and poor prognosis for overall survival in colorectal cancer patients. Elevated sCXCL5 has been proposed as a useful predictive marker for liver metastasis and overall survival in colorectal cancer.

No significant financial relationships to disclose.

Use of serum CXCL16 to predict liver metastasis and prognosis in colorectal cancer patients

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Background: Colorectal cancer (CRC) is one of the major causes of cancer death worldwide. In CRC, serum levels of CEA have become well-established prognostic indicators. However, it is not generally accepted as optimal in its prognostic power. The aim of this study was to identify novel and reliable serum prognostic markers.

Methods: We performed cytokine array to identify novel prognostic serum marker, and CXCL16 was selected. To investigate the relationships between sCXCL16 and clinicopathological findings including survival, the serum levels of CXCL16 in 237 CRC patients and 20 normal volunteers were assessed by enzyme-linked immunosorbent assay. Furthermore, we investigated proliferation, invasion and wound healing assay to investigate the biological role of CXCL16 to colon cancer cell by recombinant CXCL16 exposing to HT-29.

Results: The mean sCXCL16 concentration in patients was significantly higher than that in normal volunteers (p<0.0001). In addition, sCXCL16 levels increased significantly in accordance with the progression of UICC stage classification (p < 0.05). In clinicopathologic findings, sCXCL16 was significantly associated with the presence of lymph node (p=0.019) and the presence of liver metastases (p=0.011). Elevated sCXCL16 level demonstrated a significant association with poor survival, and was an independent risk factor for poor survival. Furthermore, sCXCL16 was an independent marker for predicting liver metastasis (logistic analysis; p=0.0015). In vitro, recombinant CXCL16 promoted epithelial mesencymal transition (EMT) phenotype characterized by impaired E-cadherin and induction of Vimentin. In addition, CXCL16 promoted cell growth, migration and invasion.

Conclusions: Our data demonstrate that preoperative sCXCL16 level increased in colorectal cancer patients, and that sCXCL16 correlated with liver metastasis, and is an independent prognostic factor for overall survival. Elevated CXCL16 has been proposed as a useful predictive marker for liver metastasis and overall survival in CRC. In vitro, CXCL16/CXCR6 axis might play an importance role in mediating cell survival, migration and invasion by EMT in CRC cell.

No significant financial relationships to disclose.

Use of co-expression of HGF and c-Met to predict peritoneal dissemination established by autocrine HGF/c-Met signaling in gastric cancer

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Background: Epithelial mesencymal transition (EMT) promotes facilitates migration and invasion of epithelial tumour cells. EMT is induced by growth factors implicated in theses process such as hepatocyte growth factor (HGF). Our aim of this study is whether HGF/c-Met pathway is associated with metastasis of gastric cancer (GC), especially in peritoneal dissemination (PD).

Methods: HGF and c-Met expression and EMT related molecules were evaluated using real-time PCR and immunohistochemistry in GC tissues. The role of HGF/c-Met pathway for EMT and anoikis was determined and c-Met TKI (SU11274) was tested for their ability to block HGF-induced biological effects in vitro and vivo.

Results: In HGF(-)c-Met(+) GC cells,recombinant HGF promoted EMT phenotype characterized by morphology, impaired E-cadherin and induction of Vimentin. HGF promoted cell growth, invasiveness, migration ability and inhibition of anoikis. SU11274 blocked HGF-induced EMT and the biological effects in vitro. In contrast of HGF(+)c-Met(+) GC cells, HGF exposure was not affected biological outcome of EMT and anoikis but SU11274 blocked biological effect as same as in HGF(-)c-Met(+) GC cells. In vivo, HGF(+)c-Met(+) GC cell line only established PD and SU11274 intraperitoneally caused an inhibition of PD growth. Clinically, HGF expression was significantly positive correlated with c-Met expression in GC specimens. Increased HGF and c-Met demonstrated a significantly associated with poor prognosis and can predict PD, respectively. Furthermore, HGF was one of the independent factors for predicting PD. Immunohistochemical analysis showed HGF and c-Met were predominantly co-expressed in cancer cell of both primary GC and PD.

Conclusions: We have demonstrated that HGF/c-Met pathway as an inducer of EMT and anoikis inhibition in GC cell. Co-expression of HGF and c-Met implicates its potential to promote PD in GC. Blocking the autocrine HGF/c-Met pathway may be clinically useful for the treatment of PD in GC.

No significant financial relationships to disclose.

Clinical significance of CD133 and hypoxia inducible factor-1α gene expression in rectal cancer after preoperative chemoradiotherapy

AIMS

The mechanism of distant recurrence in rectal cancer after preoperative chemoradiotherapy (CRT) has yet to be fully elucidated. Further improvements in survival rates cannot be achieved without decreasing distant recurrence after preoperative CRT. Recently, it was reported that hypoxic conditions were correlated with cancer stem cell generation. Therefore, we investigated the correlation between the expression of CD133 and hypoxia inducible factor-1α (HIF-1α), and their association with clinical outcome.

MATERIALS AND METHODS

Fifty-two patients with rectal cancer underwent preoperative CRT. Residual cancer cells after CRT were obtained from formalin-fixed paraffin-embedded specimens using micro-dissection. The expression levels of CD133 (PROM1) and HIF-1α genes were measured using real-time reverse transcription polymerase chain reaction. The correlation between expression and irradiation was evaluated using colon cancer cell lines. Immunohistochemical staining of these proteins after CRT was also investigated.

RESULTS

We observed a significant inverse correlation between the gene expression of CD133 (PROM1) and HIF-1α genes in residual cancer cells after CRT. Elevated CD133 gene expression was associated with distant recurrence and poor recurrence-free survival. Elevated HIF-1α gene expression was associated with poor overall survival. In vitro, the change in gene expression levels after irradiation showed inverse patterns. Immunohistochemical analyses showed that residual cancer cells strongly expressed CD133 and lacked HIF-1α expression.

CONCLUSION

Our results suggest that CD133 and HIF-1α expression is associated with tumour re-growth and distant recurrence after CRT. These results may assist in clarifying the development of future cancer therapeutics in rectal cancer patients undergoing preoperative CRT.

Development of novel thermoelectric materials by reduction of lattice thermal conductivity

Thermal conductivity is one of the key parameters in the figure of merit of thermoelectric materials. Over the past decade, most progress in thermoelectric materials has been made by reducing their thermal conductivity while preserving their electrical properties. The phonon scattering mechanisms involved in these strategies are reviewed here and divided into three groups, including (i) disorder or distortion of unit cells, (ii) resonant scattering by localized rattling atoms and (iii) interface scattering. In addition, we propose construction of a 'natural superlattice' in thermoelectric materials by intercalating an MX layer into the van der Waals gap of a layered TX₂ structure which has a general formula of (MX)_1+x (TX₂) _n (M=Pb, Bi, Sn, Sb or a rare earth element; T=Ti, V, Cr, Nb or Ta; X=S or Se and n=1, 2, 3). We demonstrate that one of the intercalation compounds (SnS)_1.2(TiS₂)₂ has better thermoelectric properties compared with pure TiS₂ in the direction parallel to the layers, as the electron mobility is maintained while the phonon transport is significantly suppressed owing to the reduction in the transverse phonon velocities.

Transmission electron microscope observation of interface structures of graphene on 6H-SiC

High-resolution transmission electron microscopic cross-sectional observations of graphene-on-SiC(0001) were carried out to directly observe the interface structure. A first principles calculation allowed us to understand the interface structures and their electronic states. Our observations revealed a metastable transitional interface structure formed by decomposition of a single SiC bilayer as well as complete honeycomb graphene formed by the decomposition of three SiC bilayers. The calculations further showed that the differences in the interface structures should strongly influence the electronic states, producing either metallic or semiconducting behavior. These results may help to resolve the controversy over the electronic states of graphene-on-SiC, and promote more accurate band-gap engineering via surface decomposition.

Gene expression profiles of epidermal growth factor receptor, vascular endothelial growth factor and hypoxia-inducible factor-1 with special reference to local responsiveness to neoadjuvant chemoradiotherapy and disease recurrence after rectal cancer surgery

AIMS

To establish a causal relationship between the gene expression profiles of angiogenetic molecular markers, including epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1 (HIF-1), in rectal cancer and the local responsiveness to neoadjuvant chemoradiotherapy and subsequent disease recurrence.

MATERIALS AND METHODS

We examined the pre-treatment tumour biopsies (n=40) obtained from patients with rectal adenocarcinoma (clinical International Union Against Cancer stage ll/III) who were scheduled to receive neoadjuvant 5-fluorouracil-based chemoradiotherapy for EGFR, VEGF and HIF-1 expression by quantitative real-time polymerase chain reaction.

RESULTS

Responders (patients with significant tumour regression, i.e. pathological grades 2/3) showed significantly lower VEGF, HIF-1 and EGFR gene expression levels than the non-responders (patients with insignificant tumour regression, i.e. pathological grades 0/1) in the pre-treatment tumour biopsies. The elevated expression level of each gene could predict patients with a low response to chemoradiation. During the median follow-up of all patients (41 months; 95% confidence interval 28-60 months), 6/40 (15%) developed disease recurrence. Although local responsiveness to neoadjuvant chemoradiotherapy was associated with neither local nor systemic disease recurrence, lymph node metastasis and an elevated VEGF gene expression level were independent predictors of systemic disease recurrence. The 3-year disease-free survival rates of the patients with lower VEGF or EGFR expression levels were significantly lower than those of patients with higher VEGF or EGFR expression levels.

CONCLUSIONS

Analysing VEGF expression levels in rectal cancer may be of benefit in estimating the effects of neoadjuvant chemoradiotherapy and in predicting systemic recurrence after rectal cancer surgery.

Duodenogastric reflux induced by endoscopic submucosal dissection

BACKGROUND AND STUDY AIMS

Endoscopic submucosal dissection (ESD) may cause excessive duodenogastric reflux (DGR) in a similar manner to distal gastrectomy, particularly after antral resections. We aimed to examine the occurrence of DGR after ESD.

PATIENTS AND METHODS

Patients with gastric neoplasm for whom ESD was indicated were categorized according to lesion site: the antral group (lower [L] stomach, n = 46) and the nonantral group (upper or middle [U or M] stomach, n = 49). Endoscopy was performed before ESD, the day after ESD, and 3 months after ESD, and the fasting bile acid concentration (BAC) in the gastric juice was analyzed.

RESULTS

BAC values showed significant interaction between time point and group, although this association differed in the antral and nonantral groups. BACs on the day after ESD were higher in the antral group than in the nonantral group, but not the pre-ESD and 3 months post-ESD levels. In the antral group only, fasting BACs increased significantly the day after ESD and decreased to baseline levels 3 months post-ESD. There was also a correlation between BAC and lesion location in the antral subgroups, with significantly higher BACs found the day after ESD in patients with lesser curvature lesions.

CONCLUSIONS

ESD of lesions in the antral lesser curvature may lead to a transient early increase in DGR. However, ESD does not result in long-term DGR, a factor that is known to increase the risk of carcinogenesis following gastrectomy.

Discovery of a tumor-specific biomarker for gastric cancer using proteomic analysis in tissue and serum

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Background: Gastric cancer is curable at an early stage. However, most cases are diagnosed at an advanced stage because of the lack of screening programs. Therefore, for early detection, there is a need for serum biomarkers to be identified. Methods: We explored surface-enhanced laser desorption/ionization time-of-flight mass spectrometry to elucidate potential protein biomarkers of gastric cancer. Twenty-one resected gastric cancer samples were compared with matched adjacent normal mucosa samples. Serum from patients with gastric cancer (n=51) was compared with patients with benign gastric diseases (n=29). Samples were analyzed on Cu2+-loaded IMAC protein chips via surface-enhanced laser desorption /ionization time-of-flight mass spectrometry. Results: Comparisons of surface-enhanced laser desorption /ionization time-of-flight mass spectrometry spectra of 21 gastric cancer tissue extracts with paired adjacent normal mucosa showed a total of 56 differentially expressed protein peaks (p<0.05; Wilcoxon test). Twenty-two were up-regulated in gastric cancer tissue, whereas 34 were down-regulated. The surface- enhanced laser desorption /ionization time-of-flight mass spectrometry spectra of serum contained 130 peaks, of which 67 were significantly associated with gastric cancer (p<0.05; Wilcoxon test). We found five proteomic features (mass charge values of 2273, 3143, 3372, 3444, 3485) that were significantly up-regulated in both gastric cancer tissue and serum from gastric cancer patients. The peak intensities of tumor-specific proteomic features were used to develop a linear regression model for calculating a diagnostic index. The area under the receiver operating characteristic curve of the corresponding diagnostic index was 0.87. Conclusions: Serum biomarker panels associated with tumor tissue are capable of distinguishing gastric cancer patients from non-cancer ones.

No significant financial relationships to disclose.

Macrophage migration inhibitory factor and long-term survival in gastric cancer

e15525

Background: Our study aimed to evaluate whether pretherapeutic serum macrophage migration inhibitory factor (MIF) is an independent factor predicting long-term survival in gastric cancer. Gastric cancer is the second leading cause of cancer-related deaths worldwide, but no satisfactory tumor marker exists. We recently found serum MIF expression was progressively increased in gastric cancer. Methods: One hundred five patients, 73 men and 32 women, mean (±SD) age 63±14 years, with histologically proven gastric adenocarcinoma were included in the study. Pretherapeutic serum was collected and MIF assayed using a commercially available enzyme-linked immunosorbent assay kit. Results: Ninety-three percent of patients received curative surgery. Mean follow up was 53.5±28.3 months, and five-year survival was 65.3 percent. The mean pretherapeutic level of MIF was 72.9ng/ml (range, 2.6 to 852.1). There were no significant correlations between serum MIF level and histopathological findings (Wilcoxon test). Mean pretherapeutic levels of carcinoembryonic antigen, C-reactive protein, and albumin were 27.5ng/ml (range, 0.1 to 778 ng/ml), 0.67mg/dl (range, 0.2 to 7.82mg/dl), and 3.6g/dl (range, 2.4 to 4.4g/dl), respectively. By multivariate analysis, serum MIF was found to be an independent factor predicting long-term survival (Odds ratio, 2.84; 95% C.I. 1.27–6.68). The five-year survival rate for patients with an MIF serum level greater than 23ng/ml was 55 percent, and that for patients with an MIF serum level less than 23ng/ml was 75 percent (p=0.03; log rank test). Conclusions: The serum level of MIF is a potentially valuable pretherapeutic prognostic factor in patients with gastric cancer.

No significant financial relationships to disclose.

Evaultion of CD133, VEGF, or EGFR as predictive markers of distant recurrence after preoperative chemoradiotherapy in rectal cancer

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Background: CD133 has been postulated to be a colon cancer stem cells (CSCs) marker. Recent investigations suggest that CSCs might contribute to cancer recurrence and resistance to conventional therapies. This study aimed to evaluate the role of CD133 in residual cancer cells after chemoradiotherapy (CRT) for rectal cancer. Methods: Forty patients with rectal cancer underwent CRT followed by surgery. Total RNAs of rectal cancer cells before (n=30) and after (n=40) CRT were isolated. Residual cancer cells after CRT were collected from formalin-fixed paraffin-embedded (FFPE) specimens using microdissection. Intratumoral CD133, vascular endothelial growth factor (VEGF), and epidermal growth factor receptor (EGFR) were measured using real-time reverse transcription polymerase chain reaction. Immunohistochemical staining of CD133 after CRT was also investigated. Results: CD133 in residual cancer cells was higher than in stromal cells on post-CRT specimens (p<0.0001). CD133 was increased in post-CRT specimens (p=0.0184), while VEGF and EGFR were decreased during CRT (p<0.0001 and p=0.0002, respectively). There were positive correlations between CD133 and VEGF (p=0.0392) or EGFR (p<0.0001) in pre-CRT specimens. Any correlations were not found in post-CRT specimens. Patients who developed distant recurrence had a higher post-CRT CD133 compared with those patients without recurrence (p=0.0136). Elevated post-CRT CD133 was associated with poor disease free survival (p=0.0168). Immunohistochemically, cytoplasmic and apical/endoluminal membranous CD133 staining was observed in residual cancer cells after CRT. Conclusions: CD133 in residual cancer cells after CRT may indicate a treatment resistant phenotype in putative CSCs. Elevated CD133 but not VEGF or EGFR on FFPE specimens may be a predictive marker of distant recurrence and poor survival after preoperative CRT in rectal cancer.

No significant financial relationships to disclose.