Weak localization in bilayer graphene with Li-intercalation/desorption

We performed in-situ electrical transport measurements for bilayer graphene grown on SiC(0 0 0 1) substrate, Li-intercalated bilayer graphene, and after that desorbing Li atoms by heating. Bilayer graphene after desorbing intercalated Li atoms showed a higher resistivity and different behavior in magnetoconductance compared to pristine bilayer graphene. We observed the weak localization of carriers at low temperatures in all the three samples and analyzed the experimental results with the extended Hikami-Larkin-Nagaoka equation to investigate the transport properties. The result shows that the magnetoconductance of pristine bilayer graphene is described by the AB stacking structure model and the phase breaking scattering is dominated by the electron-electron scattering. The intra-valley scattering occurs most frequently probably due to dopants in SiC substrate. However, in Li-desorbed graphene, the magnetoconductance can be described by neither AB nor AA-stacking model, suggesting the coexistence of domains with several different stacking structures.

Self-harm and Suicide Attempts in a Japanese Psychiatric Hospital

OBJECTIVE

Self-harm and attempted suicide are risk factors for suicide in psychiatric hospital in-patients. This study aimed to analyse the circumstances of self-harm and suicide attempts in a Japanese psychiatric hospital so as to improve management and care.

METHODS

Incident reports of self-harm and suicide attempts during a 12.4-year period from November 2000 to March 2013 were reviewed. A descriptive analysis was conducted in terms of age, sex, and diagnosis of patients, as well as level, ward, situations, and causes of incidents.

RESULTS

During the study period, 90 cases of self-harm and attempted suicide involving 58 patients were reported. The rate of self-harm and suicide attempts was 0.05 per 1000 patient-days. The types of selfharm and suicide attempts included hanging (n = 25), wrist cutting (n = 19), ingestion of foreign objects (n = 17), and others (n = 29). The single case of completed suicide involved hanging, in a patient with schizophrenia. Among 55 patients with relevant data, the most common clinical diagnosis was mood disorder (41.8%), followed by schizophrenia (36.4%). Mood disorder was 3.5 times as prevalent in females as in males (14 vs. 4). Fourteen patients with mood disorder (n = 8) or schizophrenia (n = 6) were repeatedly involved in 46 of 89 cases of self-harm or attempted suicide; 11 were female. One woman with mood disorder attempted suicide 9 times within the same year. The top 3 management and care factors related to self-harm and suicide attempts were failure to adhere to preventive procedures (28%), insufficient therapeutic communication (28%), and difficulty in predicting suicide (20%).

CONCLUSION

Self-harm and suicide attempts at this psychiatric hospital occurred at a rate of 0.05 per 1000 patient-days between late 2000 and early 2013. Efforts are needed to increase compliance with suicide prevention procedures and therapeutic communication, so as to improve management and care of psychiatric in-patients and prevent them from committing suicide.

Abstract P3-08-11: The prognostic impact of retinoic acid-induced 2 (RAI2) expression in ERα-positive breast cancer patients

Background: Breast cancer cells disseminate to the bone marrow and form bone metastases in a large majority of late-stage patients. Retinoic Acid-Induced 2 (RAI2) was reported as a putative suppressor of early hematogenous dissemination of tumor cells to the bone marrow in breast cancer, particularly in estrogen receptor α (ERα)-positive breast cancer. Here, we investigated mRNA expression of RAI-2 in breast cancer patients during long-term follow-up.

Materials and methods: A total of 451 invasive breast cancer tissues was available for analysis of RAI2 mRNA using a TaqMan PCR system. We also sought correlations between clinicopathological factors and levels of RAI2 expression in these samples. The expression of markers associated with tumor-initiating capacity, such as SNAI1, SNAI2 and VIM was also analyzed. The median follow-up period was 9.0 years. Survival curves were analyzed using the Kaplan-Meier method. Cox proportional hazards regression analysis was used for univariate and multivariate analyses of prognostic values.

Results: We found positive correlations between low expression of RAI2 mRNA and shorter disease-free survival and overall survival in breast cancer patients (P=0.003, P<0.0001, respectively), which was limited to ERα-positive patients (P=0.04, P=0.0009, respectively), and not seen in ERα-negative patients (P=0.52, P=0.27, respectively). Low RAI2 mRNA levels were positively correlated with high grade, ERα-negativity and PgR negativity. Multivariate analysis indicated that low level RAI2 mRNA expression was an independent factor for survival both overall in breast cancer and in ERα-positive breast cancer patients

Multivariate analysis (ERα-positive breast cancer patients)  OS  Multivariate patientsp valueHR(95%CI)Tumor size≤2cm1390.83691 (Reference) >2cm207 1.08(0.54-2.28)Node statusNegative176<0.00011 (Reference) Positive144 4.72(2.33-10.34)Grade11240.95921 (Reference) 2•3218 0.98(0.50-2.14)RAI2 mRNA expressionhigh140<0.00011 (Reference) middle•low206 4.79(2.14-12.78)

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Conclusion:We show that low expression of RAI2 is an independent factor predictive of a poor prognosis in ERα-positive breast cancer patients. RAI2 could be a promising candidate biomarker and therapeutic target in ERα-positive breast cancer to prevent dissemination to the bone marrow.

Citation Format: Nishikawa S, Kondo N, Endo Y, Hato Y, Hisada T, Nishimoto M, Dong Y, Okuda K, Kato H, Takahashi S, Nakanishi R, Toyama T. The prognostic impact of retinoic acid-induced 2 (RAI2) expression in ERα-positive breast cancer patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-08-11.

Clinical significance of monitoring KRAS in tissue and serum of pancreatic cancer patients

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Background: KRAS monitoring provides valuable information for early diagnosis and prediction of treatment outcome in colorectal cancer. KRAS mutation is observed in only half of colon cancer patients, whereas it is detected in 90% of pancreatic cancer patients. Therefore, investigating tumor DNA in serum by KRAS monitoring may be even more valuable in pancreatic cancer patients. In this study, we elucidated the clinical significance of KRAS monitoring in pancreatic cancer patients during treatment. Methods: KRAS in tumor tissues was analyzed for mutations by Scorpion ARMS or RASKET in 69 patients with pancreatic tumors. KRAS in serum was analyzed for mutations (G12D, G12V, G12C, G12A, G12S, G12R, G13D, Q61L, and Q61H) using droplet digital polymerase chain reaction in 58 patients who underwent the curative surgery (N = 39) or the chemotherapy (N = 19) and who had KRAS mutation in their tissues. Results: KRAS mutation in tumor tissues was detected in 62 of 69 patients (92.5%). These 62 patients showed significantly poorer prognosis (3years overall survival; 43.9%) than the seven patients without mutation (p = 0.03), who were all alive. Monitoring of KRAS in serum revealed KRAS mutation in 22 of 58 patients (37.9%). In patients who underwent the chemotherapy (N = 19), 2years OS of patients who detected KRAS mutation in serum (N = 9) was 0% and them which not detected it (N = 10) was 46.7% (p = 0.01). And in the curative resection group (N = 39), we detected KRAS mutations in serum among recurrent patients after surgery, but did not detect them among non-recurrent patients. Conclusions: KRAS mutation in serum could be a valuable predictive and prognostic biomarker in pancreatic cancer patients. Additionally, assessment of KRAS in tumor tissues may provide information about individual tumor biology. So, monitoring KRAS status of patients with pancreatic cancer may be useful of the treatment strategy.

En bloc pancreaticoduodenectomy and right hemicolectomy for locally advanced right-sided colon cancer

AIM

To assess the usefulness of en bloc right hemicolectomy with pancreaticoduodenectomy (RHCPD) for locally advanced right-sided colon cancer (LARCC).

METHODS

We retrospectively reviewed the database of Saitama Medical Center, Jichi Medical University, between January 2009 and December 2016. During this time, 299 patients underwent radical right hemicolectomy for right-sided colon cancer. Among them, 5 underwent RHCPD for LARCC with tumor infiltration to adjacent organs. Preoperative computed tomography (CT) was routinely performed to evaluate local tumor infiltration into adjacent organs. During the operation, we evaluated the resectability and the amount of infiltration into the adjacent organs without dissecting the adherent organs from the cancer. When we confirmed that radical resection was feasible and could lead to R0 resection, we performed RHCPD. The clinical data were carefully reviewed, and the demographic variables, intraoperative data, and postoperative parameters were recorded.

RESULTS

The median age of the 5 patients who underwent RHCPD for LARCC was 70 years. The tumors were located in the ascending colon (three patients) and transverse colon (two patients). Preoperative CT revealed infiltration of the tumor into the duodenum in all patients, the pancreas in four patients, the superior mesenteric vein (SMV) in two patients, and tumor thrombosis in the SMV in one patient. We performed RHCPD plus SMV resection in three patients. Major postoperative complications occurred in 3 patients (60%) as pancreatic fistula (grade B and grade C, according to International Study Group on Pancreatic Fistula Definition) and delayed gastric empty. None of the patients died during their hospital stay. A histological examination confirmed malignant infiltration into the duodenum and/or pancreas in 4 patients (80%), and no patients showed any malignant infiltration into the SMV. Two patients were histologically confirmed to have tumor thrombosis in the SMV. All of the tumors had clear resection margins (R0). The median follow-up time was 77 mo. During this period, two patients with tumor thrombosis died from liver metastasis. The overall survival rates were 80% at 1 year and 60% at 5 years. All patients with node-negative status (n = 2) survived for more than seven years.

CONCLUSION

This study showed that the long-term survival is possible for patients with LARCC if RHCPD is performed successfully, particularly in those with node-negative status.

Clinical significance of monitoring KRAS in the blood of pancreatic cancer patients

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Background: KRAS monitoring provides valuable information for early diagnosis and prediction of treatment outcome in colorectal cancer. KRAS mutation is observed in only half of colon cancer patients, whereas it is detected in 90% of pancreatic cancer patients. Therefore, investigating tumor DNA in blood by KRAS monitoring may be even more valuable in pancreatic cancer patients. In this study, we elucidated the clinical significance of KRAS monitoring in pancreatic cancer patients during treatment. Methods: KRAS in tumor tissues was analyzed for mutations by Scorpion ARMS or RASKET in 38 patients with pancreatic tumors. KRAS in blood was analyzed for mutations (G12D, G12V, G12C, G12A, G12S, G12R, G13D, Q61L, and Q61H) using droplet digital polymerase chain reaction in 23 patients who underwent chemotherapy and who had KRAS mutation in their tissues. Results: KRAS mutation in tumor tissues was detected in 27 of 38 patients (71.1%). These 27 patients showed significantly poorer prognosis (24.4 months median overall survival time [MST]) than the six patients without mutation (p = 0.04), who were all alive. Patients with mutation of 12D in tumor tissues showed better prognosis than patients with other types of mutation; thus, mutation of 12D may have a different biological effect to other mutations. Monitoring of KRAS in blood revealed KRAS mutation in 14 of 23 patients (60.9%). These 14 patients exhibited significantly poorer treatment outcomes than patients without mutation. The MST of patients with KRAS mutation in their blood was significantly shorter than that of patients without KRAS mutation (17.7 months vs. 44.3 months, p = 0.03). Conclusions: KRAS mutation in blood could be a valuable predictive and prognostic biomarker in pancreatic cancer patients who undergo chemotherapy. Additionally, assessment of KRAS in tumor tissues may provide information about individual tumor biology.

Abstract P2-03-07: Exome sequencing of human breast cancer tissues resistant to taxanes

Background: Although taxanes are a mainstay of breast cancer treatment, some cases are resistant to these drugs. This is a crucial issue in breast cancer therapy. In the emerging era of next-generation sequencing, it is possible to obtain extensive genomic information on individual tumors in a very short time. Using this technology, it was reported that specific mutations might affect therapeutic efficacy and induce resistance to specific treatment.

Objective: The aim of this study was to investigate the mechanisms of taxane resistance using whole exon sequencing and expression analyses in human breast cancer tissues.

Materials and Methods: We selected six breast cancer patients whose tumors responded well to anthracycline treatment but suffered disease progression on taxane treatment. We then performed whole exon sequencing on these samples using HiSeq (Illumia). In this way, we identified somatic mutations of candidate genes considered to be instrumental for mediating resistance to taxanes. Next, we performed mRNA expression analyses of these candidate genes in a further 122 breast cancers treated with taxanes at our institute. Finally, we correlated mRNA expression levels of these genes with clinicopathological factors and prognosis.

Results: We identified 9 mutations common to all 6 patients analyzed in this study, and a further 16 mutations shared by 5 of them. Kaplan-Meier analyses showed that high level mRNA expression of 3 of these 25 genes was significantly associated with poorer disease-free survival. Moreover, high level mRNA expression of one of these three genes was significantly associated with worse overall survival. However, there were no significant correlations between expression levels of these three genes and any clinicopathologeical features.

Conclusion: Using next-generation sequencing, we have identified three candidate genes involved in resistance to taxane treatment in breast cancer. We are now analyzing the functional attributes of these three genes.

Citation Format: Endo Y, Dong Y, Kondo N, Hato Y, Hisada T, Nishimoto M, Nishikawa S, Takahashi S, Toyama T. Exome sequencing of human breast cancer tissues resistant to taxanes [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-03-07.