[Comparison of short-term outcomes of laparoscopy-assisted and totally laparoscopic distal gastrectomy for gastric cancer]

Objective: To assess the safety, feasibility and short-term outcome of totally laparoscopic distal gastrectomy(TLDG). Methods: Seventy-five patients who underwent laparoscopic distal gastrectomy in Cancer Hospital of Chinese Academy of Medical Science between August 2015 and April 2018 were enrolled in this study. A total of 46 laparoscopy-assisted distal gastrectomy (LADG) cases and 29 TLDG cases were included. The Short-term outcomes and safeties of the two groups were compared. Results: The operation time of TLDG group was significantly longer than that of LADG group (207±41 vs. 156±34 min, P<0.001), while the length of wound was shorter in the TLDG group (3.6±0.6 vs. 5.8±0.8 cm, P<0.001). The time to first flatus in TLDG group was (3.3±0.6) days, significantly shorter than (3.7±0.8) days in LADG group (P=0.034). There were no significant differences between the two groups in the estimated blood loss, intraoperative blood transfusion, extraction of gastric tube, drainage tube removal, interval of the first time to eat semi-liquid food, postoperative hospital stays, surgical complications, number of retrieved lymph nodes, proximal and distal resection margin lengths (all P>0.05). The white blood cell count at postoperative day 1 in the TLDG group was (10.96±1.96) ×10(9)/L, significantly lower than (12.49±3.46)×10(9)/L of the LADG group (P=0.017). While the CRP level at postoperative day 1 in the TLDG group were lower than that of LADG group, no statistical difference was observed (P=0.072). Conclusions: Our study shows that TLDG is safe and feasible. TLDG has better cosmesis, less blood loss, and faster recovery compared to LADG.

Generation of induced pluripotent stem cells from a patient with hearing loss carrying GJB2 p.V37I mutation

Recessive mutations in the GJB2 gene are the most common genetic cause of hearing loss in humans. By using the Sendai-virus delivery system, we generated induced pluripotent stem cells (iPSCs) from the peripheral blood mononuclear cells of a female patient with the p.V37I (c.109G > A) mutation, a GJB2 mutation highly prevalent in the Asian population. The resulting iPSCs had a normal karyotype. The iPSCs also showed pluripotency, as confirmed by immunofluorescence staining, and differentiated into the three germ layers in vivo. This cellular model will provide a useful platform for investigating the pathogenic mechanisms of deafness related to GJB2 mutations.

Facilitating In Vivo Articular Cartilage Repair by Tissue-Engineered Cartilage Grafts Produced From Auricular Chondrocytes

BACKGROUND

Insufficient cell numbers still present a challenge for articular cartilage repair. Converting heterotopic auricular chondrocytes by extracellular matrix may be the solution.

HYPOTHESIS

Specific extracellular matrix may convert the phenotype of auricular chondrocytes toward articular cartilage for repair.

STUDY DESIGN

Controlled laboratory study.

METHODS

For in vitro study, rabbit auricular chondrocytes were cultured in monolayer for several passages until reaching status of dedifferentiation. Later, they were transferred to chondrogenic type II collagen (Col II)-coated plates for further cell conversion. Articular chondrogenic profiles, such as glycosaminoglycan deposition, articular chondrogenic gene, and protein expression, were evaluated after 14-day cultivation. Furthermore, 3-dimensional constructs were fabricated using Col II hydrogel-associated auricular chondrocytes, and their histological and biomechanical properties were analyzed. For in vivo study, focal osteochondral defects were created in the rabbit knee joints, and auricular Col II constructs were implanted for repair.

RESULTS

The auricular chondrocytes converted by a 2-step protocol expressed specific profiles of chondrogenic molecules associated with articular chondrocytes. The histological and biomechanical features of converted auricular chondrocytes became similar to those of articular chondrocytes when cultivated with Col II 3-dimensional scaffolds. In an in vivo animal model of osteochondral defects, the treated group (auricular Col II) showed better cartilage repair than did the control groups (sham, auricular cells, and Col II). Histological analyses revealed that cartilage repair was achieved in the treated groups with abundant type II collagen and glycosaminoglycans syntheses rather than elastin expression.

CONCLUSION

The study confirmed the feasibility of applying heterotopic chondrocytes for cartilage repair via extracellular matrix-induced cell conversion.

CLINICAL RELEVANCE

This study proposes a feasible methodology to convert heterotopic auricular chondrocytes for articular cartilage repair, which may serve as potential alternative sources for cartilage repair.

Using Hematuria as Detection of Post-kidney Transplantation Upper Urinary Tract Urothelial Carcinoma Is Associated With Delayed Diagnosis of Cancer Occurrence

OBJECTIVES

Kidney transplantation (KT) is an important renal replacement therapy for end-stage renal disease (ESRD). The incidence of upper urinary tract urothelial carcinoma (UTUC) is relatively higher in Taiwan. According to our institutional database, early onset of post-KT UTUC is not uncommon. Early detection of post-KT UTUC is an important issue to improve oncologic outcome. Because painless hematuria is a common symptom for UTUC, this study analyzes whether using hematuria as post-KT UTUC screening delayed cancer diagnosis or not.

METHODS

From 2005 to 2012, 128 ESRD patients were found to have UTUCs. There were 28 patients who underwent KT and were regularly followed up at our institution. All the patients underwent standard nephroureterectomy.

RESULTS

In ESRD patients with UTUC, the post-KT group revealed significantly less gross hematuria and microscopic hematuria at presentation compared with the non-KT group (43% versus 76%, P = .001 and 64% versus 86%, P = .011). For those patients with gross hematuria, non-organ-confined UTUC occurred more in the post-KT group compared with the non-KT group (42% versus 12%, P = .009). For those patients with microscopic hematuria, non-organ-confined UTUC occurred more in the post-KT group compared with the non-KT group with borderline significance (33% versus 16%, P = .085).

CONCLUSIONS

According to our observation, using gross or microscopic hematuria as detection of post-KT UTUC is associated with delayed diagnosis of cancer occurrence. Closer upper urinary tract image study such as sonography may help earlier cancer screening.

Single-Stage Cartilage Repair Using Platelet-Rich Fibrin Scaffolds With Autologous Cartilaginous Grafts

BACKGROUND

To avoid complicated procedures requiring in vitro chondrocyte expansion for cartilage repair, the development of a culture-free, 1-stage approach combining platelet-rich fibrin (PRF) and autologous cartilage grafts may be the solution.

PURPOSE

To develop a feasible 1-step procedure to combine PRF and autologous cartilage grafts for articular chondral defects.

STUDY DESIGN

Controlled laboratory study Methods: The chemotactic effects of PRF on chondrocytes harvested from the primary culture of rabbit cartilage were evaluated in vitro and ex vivo. The rabbit chondrocytes were cultured with different concentrations of PRF media and evaluated for their cell proliferation, chondrogenic gene expression, cell viability, and extracellular matrix synthesis abilities. For the in vivo study, the chondral defects were created on established animal models of rabbits. The gross anatomy, histology, and objective scores were evaluated to validate the treatment results.

RESULTS

PRF improved the chemotaxis, proliferation, and viability of the cultured chondrocytes. The gene expression of the chondrogenic markers, including type II collagen and aggrecan, revealed that PRF induced the chondrogenic differentiation of cultured chondrocytes. PRF increased the formation and deposition of the cartilaginous matrix produced by cultured chondrocytes. The efficacy of PRF on cell viability was comparable with that of fetal bovine serum. In animal disease models, morphologic, histological, and objectively quantitative evaluation demonstrated that PRF combined with cartilage granules was feasible in facilitating chondral repair.

CONCLUSION

PRF enhances the migration, proliferation, viability, and differentiation of chondrocytes, thus showing an appealing capacity for cartilage repair. The data altogether provide evidence to confirm the feasibility of 1-stage, culture-free method of combining PRF and autologous cartilage graft for repairing articular chondral defects.

CLINICAL RELEVANCE

The single-stage, culture-free method of combining PRF and autologous cartilage is useful for repairing articular chondral defects. These advantages benefit clinical translation by simplifying and potentiating the efficacy of autologous cartilage transplantation.

PARP1 controls KLF4-mediated telomerase expression in stem cells and cancer cells

Telomerase is highly expressed in cancer and embryonic stem cells (ESCs) and implicated in controlling genome integrity, cancer formation and stemness. Previous studies identified that Krüppel-like transcription factor 4 (KLF4) activates telomerase reverse transcriptase (TERT) expression and contributes to the maintenance of self-renewal in ESCs. However, little is known about how KLF4 regulates TERT expression. Here, we discover poly(ADP-ribose) polymerase 1 (PARP1) as a novel KLF4-interacting partner. Knockdown of PARP1 reduces TERT expression and telomerase activity not only in cancer cells, but also in human and mouse ESCs. Recruitment of KLF4 to TERT promoter is reduced in PARP1-suppressed cells. The poly(ADP-ribose) polymerase activity is dispensable, while the oligo(ADP-ribose) polymerase activity is required for the PARP1- and KLF4-mediated TERT activation. Repression of Parp1 in mouse ESCs decreases expression of pluripotent markers and induces differentiation. These results suggest that PARP1 recruits KLF4 to activate telomerase expression and stem cell pluripotency, indicating a positive regulatory role of the PARP1–KLF4 complex in telomerase expression in cancer and stem cells.

The data of establishing a three-dimensional culture system for in vitro recapitulation and mechanism exploration of tumor satellite formation during cancer cell transition

Tumor satellite formation is an indicator of cancer invasiveness and correlates with recurrence, metastasis, and poorer prognosis. By analyzing pathological specimens, tumor satellites formed at the tumor-host interface reflect the phenomena of epithelial-mesenchymal transition. It is impossible to reveal the dynamic processes and the decisive factors of tumor satellite formation using clinicopathological approaches alone. Therefore, establishment of an in vitro system to monitor the phenomena is important to explicitly elucidate underlying mechanisms. In this study, we explored the feasibility of creating an in vitro three-dimensional collagen culture system to recapitulate the process of tumor satellite formation. This data presented here are referred to the research article (Chen et al., 2017) [1]. Using this model, the dynamic process of tumor satellite formation could be recapitulated in different types of human cancer cells. Induced by calcium deprivation, the treated cells increased the incidence and migratory distance of tumor satellites. E-cadherin internalization and invadopodia formation were enhanced by calcium deprivation and were associated with cellular dynamic change during tumor satellite formation. The data confirmed the utility of this culture system to recapitulate dynamic cellular alteration and to explore the potential mechanisms of tumor satellite formation.

The application of individual virtual nostalgic game design to the evaluation of cognitive function

The aim of this study was to develop a task set based on personalized material for nostalgic experience, which could detect cognitive ability via a virtual experience system combined with Kinect somatosensory interactive operation applications without the user wearing any accessory input device. Fifty-nine subjects participated in the experiment. The receiver operating characteristic curve of the game system was statistically analyzed for determining the best cutoff-point in the cognitive function assessment. Correlation analysis and regression analysis were used to explore the correlations between the results and the clinical cognitive assessment scales. According to the MoCA scores, the results showed that the accuracy of the system was 86.4% in evaluating mild cognitive impairment. The system seems feasible and was strongly correlated with clinical cognitive assessment scales. We anticipate that daily use of our system could keep track of changes of cognitive function of the elderly in home life.

Subcellular Localization of Survivin Determines Its Function in Cardiomyocytes

Rationale:Reducing cardiomyocyte death and enhancing their proliferation after myocardial infarction is perhaps the single largest challenge for cardiac tissue regeneration. Survivin (SVV) is the smallest member of the inhibitor of apoptosis (IAP) family but plays two important roles; inhibiting caspase-9 activation in the intrinsic apoptosis pathway, and regulating microtubule dynamics and chromosome segregation during cell division. Genetic depletion of cardiac SVV leads to incomplete cardiomyocyte division and abnormal heart development. However, the function of SVV in adult hearts after myocardial infarction remains unclear.

Methods: A homozygous inducible cardiomyocyte-specific SVV knockout transgenic mouse model was established through crossbreeding SVV^flox/flox and αMHC-MCM transgenic mice. Adult mice received consecutive intraperitoneal injection of tamoxifen to induce genetic removal of SVV in cardiomyocytes. A SVV overexpressing model was established via local delivery of SVV in wild-type mouse hearts.

Results: We found that 30.82% of cardiomyocytes in the peri-infarct region of SVV knockout mice were apoptotic, significantly higher than the 22.18% in control mice. In addition, ejection fraction was 29.00±0.40% in knockout mice compared to 38.04±0.50% in control mice 21 days after myocardial infarction. On the contrary, locally overexpressing SVV in the heart improved cardiac functions. Unexpectedly, we found that altering the subcellular localization of SVV overexpression produced different outcomes. Overexpression of SVV in the cytoplasm decreased cardiomyocyte apoptosis, whereas overexpression of SVV in the nucleus enhanced cardiac regeneration. The ejection fraction of mice overexpressing SVV was 36.58±0.91%, significantly higher than 28.18±1.70% in the GFP control group. Apoptotic cardiomyocytes were only 4.63% in mouse overexpressing cytosolic SVV, compared to 9.31% in the GFP group, and activation of caspase-3 was also reduced. Moreover, mice overexpressing NLS-SVV exhibited a better ejection fraction (36.19±1.02%,) than GFP controls (26.69±0.75%). NLS-SVV enhanced H3P-positive cardiomyocytes in the border zone to 0.28%, compared to only 0.08% in GFP group, through interacting with Aurora B.

Conclusions:We demonstrate the importance of SVV subcellular localization in regulating post-MI cardiac repair and regeneration. We hope that this will open new translational approaches through targeted delivery of SVV.

Mobilizing Transit-Amplifying Cell-Derived Ectopic Progenitors Prevents Hair Loss from Chemotherapy or Radiation Therapy

Genotoxicity-induced hair loss from chemotherapy and radiotherapy is often encountered in cancer treatment, and there is a lack of effective treatment. In growing hair follicles (HF), quiescent stem cells (SC) are maintained in the bulge region, and hair bulbs at the base contain rapidly dividing, yet genotoxicity-sensitive transit-amplifying cells (TAC) that maintain hair growth. How genotoxicity-induced HF injury is repaired remains unclear. We report here that HFs mobilize ectopic progenitors from distinct TAC compartments for regeneration in adaptation to the severity of dystrophy induced by ionizing radiation (IR). Specifically, after low-dose IR, keratin 5⁺ basal hair bulb progenitors, rather than bulge SCs, were quickly activated to replenish matrix cells and regenerated all concentric layers of HFs, demonstrating their plasticity. After high-dose IR, when both matrix and hair bulb cells were depleted, the surviving outer root sheath cells rapidly acquired an SC-like state and fueled HF regeneration. Their progeny then homed back to SC niche and supported new cycles of HF growth. We also revealed that IR induced HF dystrophy and hair loss and suppressed WNT signaling in a p53- and dose-dependent manner. Augmenting WNT signaling attenuated the suppressive effect of p53 and enhanced ectopic progenitor proliferation after genotoxic injury, thereby preventing both IR- and cyclophosphamide-induced alopecia. Hence, targeted activation of TAC-derived progenitor cells, rather than quiescent bulge SCs, for anagen HF repair can be a potential approach to prevent hair loss from chemotherapy and radiotherapy. Cancer Res; 77(22); 6083-96. ©2017 AACR.

[Surgical treatment and prognosis of pancreatic neuroendocrine carcinoma]

Objective: Pancreatic neuroendocrine carcinoma (pNEC) is a highly malignant tumor.This study aimed to evaluate the role of surgery and the prognosis for patients with pancreatic neuroendocrine carcinoma (pNEC). Methods: We collected and reviewed all clinical data of patients who underwent radical surgery for pNEC from Jan 2000 through Jan 2016 in our hospital. Cox-regression analysis wasused to evaluate the factors potentially influencing survival. Results: Twenty patients including 11 males and 9 females (median age, 62.5 years) were included in this study. All patients underwent radical surgery and 17 cases received postoperative platinum-based chemotherapy.The median follow-up time was 41 months (range, 1 to 127 months). The 1-, 3-, and 5-year survival rates of the patients were 66.7%, 51.5% and 28.1%, with a median survival time of 75.3 months.The multivariate analysis indicated that tumor size and Ki-67 index were of prognostic significance. Conclusions: Pancreatic neuroendocrine carcinomas are rare but increasing in incidence. Patients with localized nonmetastatic primary tumors seem to benefit from surgery. Early diagnosis and multimodality therapy are key points of an improved survival.

Nanometre-scale 3D defects in Cr2AlC thin films

MAX-phase Cr₂AlC containing thin films were synthesized by magnetron sputtering in an industrial system. Nanometre-scale 3D defects are observed near the boundary between regions of Cr₂AlC and of the disordered solid solution (CrAl)_xC_y. Shrinkage of the Cr-Cr interplanar distance and elongation of the Cr-Al distance in the vicinity of the defects are detected using transmission electron microscopy. The here observed deformation surrounding the defects was described using density functional theory by comparing the DOS of bulk Cr₂AlC with the DOS of a strained and unstrained Cr₂AlC(0001) surface. From the partial density of states analysis, it can be learned that Cr-C bonds are stronger than Cr-Al bonds in bulk Cr₂AlC. Upon Cr₂AlC(0001) surface formation, both bonds are weakened. While the Cr-C bonds recover their bulk strength as Cr₂AlC(0001) is strained, the Cr-Al bonds experience only a partial recovery, still being weaker than their bulk counterparts. Hence, the strain induced bond strengthening in Cr₂AlC(0001) is larger for Cr d – C p bonds than for Cr d – Al p bonds. The here observed changes in bonding due to the formation of a strained surface are consistent with the experimentally observed elongation of the Cr-Al distance in the vicinity of nm-scale 3D defects in Cr₂AlC thin films.

[Surgical treatment and curative effect observation of vascular malformations in the adult floor of the mouth and pharyngeal space]

Objective:To investigate the effect of surgical treatment of vascular malformation in the adult floor of the mouth and pharyngeal space. Method:Collect 12 cases of vascular malformation from the floor of the mouth and pharyngeal space.All of them were checked out of the different degrees of tongue elevation and dysphagia and to carry out the excision of vascular malformation with lingual nerve and hypoglossal nerve preservation. Result:The lesion reduction degree of 10 cases of patients were Ⅳ class(excellent), theoher 2 cases were Ⅲ class(good). Hematoma at the bottom of the mouth after operation were not happened. Follow-up 0.5-3 years,tongue deviation appeared in 1 cases of postoperation. After 6 months of follow-up, the tongue is in the middle when it put out, functional recovery,no tongue muscle atrophy,no tongue movement disorder in the rest of the patients,no obvious recurrence of vascular malformations, no swallowing disorder in all patients. Conclusion:It would be obtained ideal therapeutic effect with surgical treatment in the adult vascular malformations of the floor of the mouth and pharyngeal space.It would be the key to the success of surgery with protecting the lingual nerve and hypoglossal nerve and controlling bleeding.

Aerosol synthesis of phase-controlled iron-graphene nanohybrids through FeOOH nanorod intermediates

Iron-based nanoparticles form the basis for a host of sustainable alternative technologies based on this earth-abundant, low-toxicity element that can adopt a variety of oxidation states, crystal phases, and functions. Control of size, shape, and phase stability is a challenge for many nano-iron-based technologies, especially those involving Fe0 that is susceptible to oxidation under ambient conditions. This article presents a continuous method for hybridizing Fe-based nanoparticles with carbon in the form of graphene-encapsulated Fe-based particles with core-shell symmetry that allows flexible control of iron particle size, shape, and phase stability. The method uses FeOOH nanorods and graphene oxide as precursors, and subjects them to an aerosol-phase microdroplet drying and annealing process to yield a range of Fe/C nanohybrids whose structure can be controlled through adjustment of aerosol process temperature and post-synthesis thermal treatment conditions. We demonstrate that FeOOH nanorods can be successfully encapsulated in graphene, and transform during annealing into encapsulated Fe3O4 or Fe0 nanoparticles by reductive fragmentation, where the graphene nanosack acts as a carbothermic reductant. The hybrids are characterized by vibrating sample magnetometry and Cr(VI) reduction rates in aqueous media. The Fe0-graphene hybrids show high activity, good stability, and good recyclability in aqueous Cr(VI) removal due to the effect of graphene encapsulation. The present work suggests this rapid and continuous synthesis method can produce stable Fe-based materials, and can be extended to other metal systems, where graphene encapsulation can induce in situ reduction of metal oxide precursors into zero-valent metal-graphene hybrids.

Abstract B44: Accelerated mouse colorectal cancer progression in the presence of EHMT2 overexpression

In the last 5 years, the prevalence of colorectal cancer (CRC) has increased worldwide and has surpassed that of liver cancer. Even after treatment for primary CRC, patients still have a high risk (30%–50%) of cancer recurrence, generally from metastasis. Thus, if we can uncover the progressive mechanisms of CRC and identify a novel drug target, current treatment regimens and the survival of patients with advanced stage CRC can be improved. Euchromatin histone lysine N-methyl transferase 2 (EHMT2) inhibition is considered an effective therapeutic strategy for cancer treatment because its inhibitors, BIX-01294 and UNC0639, can induce autophagy-dependent cell death. However, the function of EHMT2 in CRC progression remains largely unclear. In this study, we established a colonic stem-cell-specific EHMT2 activation combined with sporadic (AOM/DSS-induced) or hereditary (Apc mutant) CRC mouse models. In the EHMT2-overexpressed group, many colonic tumors larger than 3 mm in size were found in the 24 weeks after tumor induction. Histological analysis of these tumors showed that the adenocarcinomatous glands became highly irregular, and these glands were difficult to discern, one of the characteristic of malignant CRC. In the 52 weeks after tumor induction, we reproducibly observed CRC liver metastases. Further analysis by RNA sequencing combined with gene set enrichment analysis determined that the anti-apoptosis-related and Wnt-signaling gene sets can be enriched in the EHMT2-overexpressed group. Using the chromatin immunoprecipitation assay, we demonstrated that EHMT2 directly targeted the caspase8 proximal promoter region and increased the level of H3 lysine9 di-methylation in this region. Several functional assays supported that this gene regulation may have conferred opportunities for CRC cells to avoid the cytotoxicity of anticancer drugs. Overall, aberrant EHMT2 expression is conducive to CRC progression.

Citation Format: Kang-Yu Tai, I-Shing Yu, Shih-Ting Cha, Shu-Wha Lin, Min-Liang Kuo, You-Tzung Chen. Accelerated mouse colorectal cancer progression in the presence of EHMT2 overexpression. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Sep 24-27, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2016;76(2 Suppl):Abstract nr B44.

Serum level of endothelial cell-specific molecule-1 and prognosis of colorectal cancer

We evaluated the clinical significance and explored the prognostic value of serum endothelial cell-specific molecule-1 (ESM-1) expression in colorectal cancer (CRC) in a Chinese population. Serum samples were obtained from 89 CRC patients undergoing surgical treatment and 90 healthy volunteers (control group). ESM-1 levels in serum samples from CRC patients and controls were measured using a sandwich enzyme-linked immunosorbent assay. Overall survival was analyzed by the log-rank test, and survival curves were plotted according to the Kaplan-Meier method. Univariate Cox regression was performed on each clinical covariate to examine its influence on patient survival. Final multivariate models were based on step-wise addition. Serum ESM-1 expression levels were significantly higher in patients with CRC (66.81 ± 22.97 pg/mL) than in healthy volunteers (31.50 ± 16.81 pg/mL, P = 0.012). Expression levels of ESM-1 in CRC patients were significantly correlated with histological differentiation (P = 0.004), TNM stage (P = 0.007), depth of tumor invasion (P = 0.02), and lymph node metastasis (P = 0.001). Kaplan-Meier survival curves revealed that the overall survival was significantly lower in patients with high ESM-1 levels than in those with low levels (29.43 vs 61.20%, P = 0.0166). Multivariate analysis confirmed that the hazard risk of death was significantly higher in patients with high serum ESM-1 expression compared with low expression (hazard risk = 4.09, 95% confidence interval: 2.27-10.88, P < 0.001). Detection of ESM-1 levels in the serum may serve as a tumor biomarker for assessing prognosis in CRC.

Ministry of Health Clinical Practice Guidelines: Diabetes Mellitus

The Ministry of Health (MOH) have updated the clinical practice guidelines on Diabetes Mellitus to provide doctors and patients in Singapore with evidence-based treatment for diabetes mellitus. This article reproduces the introduction and executive summary (with recommendations from the guidelines) from the MOH clinical practice guidelines on Diabetes Mellitus, for the information of SMJ readers. Chapters and page numbers mentioned in the reproduced extract refer to the full text of the guidelines, which are available from the Ministry of Health website: http://www.moh.gov.sg/content/moh_web/healthprofessionalsportal/doctors/guidelines/cpg_medical.html. The recommendations should be used with reference to the full text of the guidelines. Following this article are multiple choice questions based on the full text of the guidelines.

Excitons and biexcitons in InGaN quantum dot like localization centers

Indium segregation in a narrow InGaN single quantum well creates quantum dot (QD) like exciton localization centers. Cross-section transmission electron microscopy reveals varying shapes and lateral sizes in the range ∼1-5 nm of the QD-like features, while scanning near field optical microscopy demonstrates a highly inhomogeneous spatial distribution of optically active individual localization centers. Microphotoluminescence spectroscopy confirms the spectrally inhomogeneous distribution of localization centers, in which the exciton and the biexciton related emissions from single centers of varying geometry could be identified by means of excitation power dependencies. Interestingly, the biexciton binding energy (E(b)xx) was found to vary from center to center, between 3 to -22 meV, in correlation with the exciton emission energy. Negative binding energies are only justified by a three-dimensional quantum confinement, which confirms QD-like properties of the localization centers. The observed energy correlation is proposed to be understood as variations of the lateral extension of the confinement potential, which would yield smaller values of E(b)xx for reduced lateral extension and higher exciton emission energy. The proposed relation between lateral extension and E(b)xx is further supported by the exciton and the biexciton recombination lifetimes of a single QD, which suggest a lateral extension of merely ∼3 nm for a QD with strongly negative E(b)xx = -15.5 meV.

Abstract 3495: A nucleolus-predominant piggyBac transposase increases transposition efficiency in human cancer cells

PiggyBac is a prevalent transposon system used to deliver transgenes into and to functionally explore the mammalian untouched genomic territory. Efforts to increase its transposition efficiency in mammals through engineering the corresponding transposase (PBase) codon usage to improve its expression level is reported. The hyperactive PBase developed through screening for mutant variants are also established. To increase the safety for its potential use in regenerative medicine applications, site-specific transposition using engineered Zn finger-, Gal4- fused PBase, and an excision-prone PBase variant are also successfully developed. Here we report the construction of a nucleolus predominant PBase, NP-mPB, by adding a nucleolus predominant (NP) signal peptide from HIV-1 TAT protein to a mammalian codon optimized PBase (mPB). Although there is a predominant fraction of the NP-mPB-tGFP fusion proteins concentrated in the nucleoli, an insertion site preference toward nuleolar organizer regions (NORs) is not detected. Instead a 3-fold increase in piggyBac transposition efficiency is found in human cancer cell line.

Citation Format: Jin-Bon Hong, Fu-Ju Chou, Amy T. Ku, Hsiang-Hsuan Fan, Tung-Lung Lee, Yung-Hsin Huang, I-Chang Su, You-Tzung Chen. A nucleolus-predominant piggyBac transposase increases transposition efficiency in human cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3495. doi:10.1158/1538-7445.AM2014-3495

Conduction control at ferroic domain walls via external stimuli

Intriguing functionalities at nano-sized domain walls have recently spawned a new paradigm for developing novel nanoelectronics due to versatile characteristics. In this study, we explore a new scenario to modulate the local conduction of ferroic domain walls. Three controlling parameters, i.e., external electrical field, magnetic field and light, are introduced to the 90° domain walls (90° DWs) of BiFeO₃. Electrical modulation is realized by electrical transport, where the mobility of 90° DWs can be altered by gating voltage. We further use the ferromagnetic/antiferromagnetic coupling to reveal the inherent magnetism at the DWs. With an established magnetic nature, magnetotransport has been conducted to introduce magnetic controlling parameter, where a giant positive magnetoresistance change can be observed up to 200%. In addition, light modulated conduction, a core factor for multifunctional applications, is successfully demonstrated (current enhancement by a factor of 2 with 11 W white lamp). These results offer new insights to discover the tunability of domain wall nanoelectronics.