Amplifier for scanning tunneling microscopy at MHz frequencies

Conventional scanning tunneling microscopy (STM) is limited to a bandwidth of a few kHz around DC. Here, we develop, build, and test a novel amplifier circuit capable of measuring the tunneling current in the MHz regime while simultaneously performing conventional STM measurements. This is achieved with an amplifier circuit including a LC tank with a quality factor exceeding 600 and a home-built, low-noise high electron mobility transistor. The amplifier circuit functions while simultaneously scanning with atomic resolution in the tunneling regime, i.e., at junction resistances in the range of giga-ohms, and down towards point contact spectroscopy. To enable high signal-to-noise ratios and meet all technical requirements for the inclusion in a commercial low temperature, ultra-high vacuum STM, we use superconducting cross-wound inductors and choose materials and circuit elements with low heat load. We demonstrate the high performance of the amplifier by spatially mapping the Poissonian noise of tunneling electrons on an atomically clean Au(111) surface. We also show differential conductance spectroscopy measurements at 3 MHz, demonstrating superior performance over conventional spectroscopy techniques. Further, our technology could be used to perform impedance matched spin resonance and distinguish Majorana modes from more conventional edge states.

Atomic scale shot-noise using cryogenic MHz circuitry

By implementing dedicated cryogenic circuitry operating in the MHz regime, we have developed a scanning tunneling microscope (STM) capable of conventional, low frequency (<10 kHz), microscopy as well spectroscopy and shot-noise detection at 1 MHz. After calibrating our AC circuit on a gold surface, we illustrate our capability to detect shot-noise at the atomic scale and at low currents (<1 nA) by simultaneously measuring the atomically resolved differential conductance and shot-noise on the high temperature superconductor Bi₂Sr₂CaCu₂O_8+x . We further show our direct sensitivity to the temperature of the tunneling electrons at low voltages. Our MHz circuitry opens up the possibility to study charge and correlation effects at the atomic scale in all materials accessible to STM.

Ultrasensitive Displacement Noise Measurement of Carbon Nanotube Mechanical Resonators

Mechanical resonators based on a single carbon nanotube are exceptional sensors of mass and force. The force sensitivity in these ultralight resonators is often limited by the noise in the detection of the vibrations. Here, we report on an ultrasensitive scheme based on a RLC resonator and a low-temperature amplifier to detect nanotube vibrations. We also show a new fabrication process of electromechanical nanotube resonators to reduce the separation between the suspended nanotube and the gate electrode down to ∼150 nm. These advances in detection and fabrication allow us to reach [Formula: see text] displacement sensitivity. Thermal vibrations cooled cryogenically at 300 mK are detected with a signal-to-noise ratio as high as 17 dB. We demonstrate [Formula: see text] force sensitivity, which is the best force sensitivity achieved thus far with a mechanical resonator. Our work is an important step toward imaging individual nuclear spins and studying the coupling between mechanical vibrations and electrons in different quantum electron transport regimes.

[Research advances in the v-raf murine sarcoma viral oncogene homolog gene mutation in ameloblastoma]

V-raf murine sarcoma viral oncogene homolog B1 (BRAF) is a pro-oncogene, which is one member of the RAF family. Mutated BRAF is found in approximately 8% of human tumors. BRAF gene mutations lead to continuous activation of the mitogen-activatd protein kinase (MAPK) pathway, which resulting in abnormal cell proliferation and tumorigenesis. In recent years, recurrent MAPK signaling mutations were identified in ameloblastoma, among which BRAF-V600E is the most prominent type. This provides new strategies for the targeted treatment of ameloblastoma. This paper reviewed the latest advances in BRAF gene mutation associated with ameloblastoma and its potential clinical significance.

[Prevalence and clinical features of familial hypercholesterolemia in Chinese patients with myocardial infarction]

Objective: To analyze the prevalence and clinical features of familial hypercholesterolemia (FH) in Chinese patients with myocardial infarction (MI). Method: This retrospective study recruited a total of 2 119 consecutive patients (age (56.7±10.9) years old) undergoing coronary angiography with first MI from April 2011 to December 2016. Patients were divided into 2 groups: premature MI (male<55 years old, female<60 years old) and non-premature MI. The diagnosis of FH was established according to Dutch Lipid Clinic Network (DLCN) diagnostic criteria and referred as definite/probable FH in our study. The prevalence and clinical features of FH, including lipid level, MI characteristics and stain therapy, were explored. Multivariable logistic regression analysis was used to assess the predictive value of FH for the presence of premature MI. Results: The prevalence of definite/probable FH was 3.68% (78/2 119) in MI patients and 7.28% (68/934) in premature MI patients. Onset of MI occurred 10 years earlier in patients with definite/probable FH than those without FH ((47.9±9.4) years vs. (58.8±10.7) years, P<0.01). Additionally, we found that the risk of premature MI was significantly and independently increased in definite/probable FH patients (OR=5.32, 95%CI 2.77-10.22, P<0.01). None of FH patients reached the target of LDL-C<1.8 mmol/L under statin therapy. Conclusions: The prevalence of FH in Chinese patients with MI is not rare. Clinically, FH is linked with the early onset of MI.

Abstract P6-07-02: Bisphenol A treatment induces hyperplasia in primary and stem cell-generated mammary glands from pregnant mice

Breast cancer is a commonly diagnosed cancer of pregnancy. However, how endogenous and exogenous endocrine factors may contribute to the development of pregnancy-associated mammary tumorigenesis is not clear. There is growing evidence that mammary stem cells (MaSCs) may initiate neoplastic transformation when dysregulated in mouse models. We investigated the effect of the environmental endocrine disruptor bisphenol A (BPA) on mouse mammary gland morphology, epithelial cell composition, pre-neoplastic lesions, and the regenerative function of MaSCs. Pregnant FVB mice with GFP transgene on Day E8.5 were implanted with osmotic pumps that constantly release BPA at 0, 25 or 250 ng/kg/day for 28 days and the mice were euthanized one month after weaning. In agreement with the literature, we observed an abnormality of the morphology of the mammary gland after BPA treatment characterized by higher duct density and abnormal secondary and tertiary branching. Quantification of percent hyperplastic mammary ducts in H&E-stained tissue slides revealed a significant increase of ducts with hyperplastic lesions after BPA treatment, particularly with the low dose. To investigate the effects of BPA treatment on MaSCs, we used enzyme digestion to isolate the CD24hi/CD49f+ luminal epithelial cells (also termed as colony forming cell or CFC) and the CD24+/CD49fhi basal epithelial cells (also termed as mammary repopulating unit or MRU) from mammary gland tissues by FACS and found no significant difference in percent of luminal or basal cell population after BPA treatment. Because the basal cells are enriched with MaSCs that can form mammospheres in suspension culture and subsequently form solid 3D organoids when cultured in Matrigel, we transplanted the solid 3D organoids into cleared mammary fat pads of syngeneic FVB mice and immune-compromised nude mice to examine how BPA treatment might alter MaSC function. Significantly, similar to the results from the primary mammary glands, the regenerated mammary glands by MaSCs from mice treated with the low dose of BPA showed increased duct density, secondary and tertiary branching, and a significantly greater number of hyperplastic lesions. Taken together, our study demonstrated that BPA exposure at very low dose could induce pre-neoplastic lesions in the mammary gland of pregnant mice, apparently by directly targeting MaSCs and implicates BPA as an exogenous endocrine factor that may promote pregnancy-associated mammary tumorigenesis.

Citation Format: Bouamar H, Zhang F, Gu X, Dong Q, Sun L. Bisphenol A treatment induces hyperplasia in primary and stem cell-generated mammary glands from pregnant mice [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 P6-07-02.

[The role and significance of digital reconstruction technique in liver segments based on portal vein structure]

Objective: To study the segment of liver according to the large amount of three-dimensional(3D) reconstructive images of normal human livers and the vascular system, and to recognize the basic functional liver unit based on the anatomic features of the intrahepatic portal veins. Methods: The enhanced CT primitive DICOM files of 1 260 normal human livers from different age groups who treated from October 2013 to February 2017 provided by 16 hospitals were analyzed using the computer-aided surgery system.The 3D liver and liver vascular system were reconstructed, and the digital liver 3D model was established.The vascular morphology, anatomical features, and anatomical distributions of intrahepatic portal veins were statistically analyzed. Results: The digital liver model obtained from the 3D reconstruction of CAS displayed clear intrahepatic portal vein vessels of level four.Perform a digital liver segments study based on the analysis of level four vascular distribution areas.As the less anatomical variation of left hepatic portal vein, the liver was classified into four types of liver segmentation mainly based on right hepatic portal vein.Type A was similar to Couinaud or Cho's segmentation, containing 8 segments(537 cases, 42.62%). Type B contained 9 segments as there are three ramifications of right-anterior portal vein(464 cases, 36.82%). The main difference for Type C was the variation of right-posterior portal vein which was sector shape(102 cases, 8.10%). Type D contained the cases with special portal vein variations, which needs three-dimensional simulation to design individualized liver resection plan(157 cases, 12.46%). These results showed that there was no significant difference in liver segmental typing between genders(χ(2)=2.179, P=0.536) and did not reveal any significant difference in liver segmental typing among the different age groups(χ(2)=0.357, P=0.949). Conclusions: The 3D digital liver model can demonstrate the true 3D anatomical structures, and its spatial vascular variations.The observation of anatomic features, distribution areas of intrahepatic portal veins and individualized liver segmentation achieved via digital medical 3D visualization technology is of great value for understand the complexity of liver anatomy and to guide the precise hepatectomy.

[A multicenter clinical study for the comparison of S-1 versus capecitabine in the treatment of advanced breast cancer]

Objective: To investigate the safety, efficacy and prognostic factors of S-1 versus capecitabine in patients with advanced breast cancer (ABC). Methods: From January 1, 2012 to December 31, 2014, 154 ABC patients with pathological diagnosis were separated into two groups: S-1 with or without the 3rd generation chemotherapy drug (group S-1) and capecitabine with or without the 3rd generation chemotherapy drug (Group capecitabine). The efficacy, side effects and prognostic factors were compared between the two groups. Results: There were 70 patients in group S-1 and 84 patients in group capecitabine. The objective response rates (ORR) were 31.4% (22/70) in group S-1 and 28.6% (24/84) in group capecitabine. The disease control rates (DCR) were 74.3% (52/70) and 83.3% (70/84), respectively. There were no significant differences in DCR and ORR between two groups (P>0.05). The DCR of patients treated with capecitabine monotherapy was significantly higher than that of S-1 monotherapy [94.4%(17/18) and 64.0%(16/25), P=0.028]. The median PFS was 7.5 and 8.9 months for the patients in the group S-1 and group capecitabine, with no statistically significant difference (P=0.423). The 1-year survival rates of group S-1 and group capecitabine were 81.4% and 66.7%, respectively, with no significant differences(P=0.020). Univariate analysis showed that ER and/or PR status (P=0.004), T stage (P=0.041), and molecular typing (P=0.046) were associated with PFS. Multivariate analysis showed ER and/or PR status (P=0.034) was an independent prognostic factor related with PFS. The incidence of hemoglobin reduction was 14.3% (10/70) and 36.9% (31/84) in the group S-1 and group capecitabine, and the differences were statistically significant (P=0.002). There was no significant difference in the incidence of leukopenia, neutropenia, thrombocytopenia and hand-foot syndrome between the two groups(P>0.05). Conclusions: S-1 and capecitabine are both effective for advanced breast cancer. Neither ORR nor DCR were significantly different between these two groups. The incidence of gastrointestinal reactions and thrombocytopenia of S-1 was slightly lower than that of capecitabine.

[Neovascularization aggravated hepatic fibrosis in combined hypoxia NASH rat model]

Objective: To optimize the construction of combined hypoxia NASH rat model on the basis of preliminary work, and to explore the role of neovascularization in the process of hepatic fibrosis. Methods: 32 rats were divided randomly to four groups that were null control group(A group ), hypoxia group(B group), high fat diet group(C group ) and high fat diet plus hypoxia group (D group ),treated with null , Intraperitoneal injection of NaNO(2), high fat diet and high fat diet plus Intraperitoneal injection of NaNO(2) respectively. Every group was observed for 16 weeks, B and D group was treated with Intraperitoneal injection of NaNO(2) 20 mg/kg.d at the laster 8 weeks. Liver histology NASH activity score(NAS) and Fibro score(FibroS), biochemical index were detected in this combined hypoxia NASH rat model(D group), meanwhile the changes of HIF1α, inflammatory factor and neovascularization were measured by ELISA, realtime PCR and immunohistochemistry. Results: Liver tissue NAS > 4 was seen in C and D group. D group showed NASH characteristics, including significantly steatosis at liver acinar 3 area(mostly a microvesicular type fat droplets mixed with macrovesicular type), hepatocyte balloon degeneration, obvious lobular inflammation, while fibrosis score increased significantly, including visible hepatic sinusoid fibrosis, fibrosis around portal vein, and bridging fibrosis in a considerable portion of the rats. Compared with C group, biochemical indicators of aspartate aminotransferase (AST), HIF1α, neovascularization-related VEGFA, VEGFR2 mRNA level increased obviously and the expression of immunohistochemistry VEGFR2, CD34 enhanced markedly in D group(p < 0.05). Conclusion: A combined hypoxia NASH rat model can be established throught feeding 16 weeks' high-fat diet then intraperitoneal injection of NaNO(2) 20 mg / kg.d at the laster 8 weeks, meanwhile chronic hypoxia can accelerate this combined hypoxia NASH model liver fibrosis process. In this process neovascularization promoted the formation of hepatic fibrosis in this model.

DYNAMIC CHANGES OF TRAb AND TPOAb AFTER RADIOIODINE THERAPY IN GRAVES' DISEASE

Context

To analyze the dynamic changes of serum thyrotrophin receptor antibody (TRAb) and thyroid peroxidase antibody (TPOAb) in Graves' disease (GD) patients before and after radioactive iodine (RAI) treatment and to investigate if TRAb and TPOAb play a role in the occurrence of early hypothyroidism after ¹³¹I therapy for Graves' hyperthyroidism.

Subjects and Methods

A total of 240 patients newly diagnosed with GD were selected to study. A clinical and laboratory assessment was performed before and at 3, 6, and 12 months after ¹³¹I therapy. Chemiluminescent immunoassays were used to detect serum free triiodothyronine (FT3), free thyroxine (FT4), sensitive thyroid-stimulating hormone (TSH) and TPOAb concentration. Radio-receptor assay was used to measure serum TRAb concentration. According to the early onset of hypothyroidism in a year after RAI therapy, patients were divided into early hypothyroidism group (group A) and non-early hypothyroidism group (group B).

Results

In both groups, serum TRAb and TPOAb increased at 3 months, reached the highest level at 6 months and returned to the baseline at 12 months after RAI therapy. TRAb showed a significant difference between the two groups at 6 months (P<0.01). Serum TPOAb in group A was higher than that in group B before and at 3, 6, 12 months after RAI therapy (P<0.05).

Conclusions

Serum TRAb and TPOAb are closely related to the occurrence of the early hypothyroidism, and play an important role in judging prognosis after ¹³¹I treatment in Graves' disease.

Facile preparation of S-doped magnetite hollow spheres for highly efficient sorption of uranium(vi)

S-Doped magnetite hollow spheres (S-doped MHS) were prepared, which exhibit fast and efficient sorption for uranium(vi).

[Relationship and clinicopathological significance of Numb and epithelial-mesenchymal transition related proteins in human pancreatic cancer]

Objective: To study the relationship and clinicopathological significance of Numb and epithelial-mesenchymal transition related proteins in human pancreatic cancer(PC). Methods: Sixty-three cases of pancreatic cancer tissues were obtained from department of gastrointestinal surgery in the First Hospital of China Medical University from January 2005 to December 2012, all samples were histopathologically proved to be adenocarcinoma. The expressions of Numb, E-cadherin and Vimentin proteins in 63 cases of pancreatic cancer specimens were detected by immunohistochemistry. Western blot and real-time PCR were used to examine the protein and mRNA levels in two pancreatic cancer cell lines. Pearson and chi-squared tests were used to analyze the relationship and clinicopathological characters with PC patients. Kaplan-Meier curve and log rank test were used to estimate the difference of PC patients' survival. Results: The positive rates of Numb, E-cadherin and Vimentin expressions were 46.0%, 41.3% and 28.6%, respectively. Numb expression was negatively associated with tumor size, differentiation and UICC stage(r=-0.310, P=0.010; r=-0.359, P=0.004; r=-0.228, P=0.020), while E-cadherin expression was negatively related with tumor differentiation(r=-0.316, P=0.012). In contrast, Vimentin expression was positively related with pancreatic cancer differentiation and lymph metastasis(r=0.264, P=0.036; r=0.274, P=0.030). Correlation analysis showed Numb had a positive association with E-cad expression(r=0.325, P=0.010), but had no association with Vimentin. Moreover, patients with co-expression of Numb and E-cadherin had a significantly better overall survival in Kaplan-Meier univariate analysis(P=0.046). Immunoblotting and real-time PCR showed that high Numb protein and mRNA levels in BxPC-3 cells were followed with high E-cadherin and low Vimentin expressions, whereas low Numb protein and mRNA levels in PANC-1 cells were followed with low E-cadherin and high Vimentin expressions, respectively. Conclusions: Numb has a positive relationship with E-cadherin in both pancreatic cancer tissues and cells.The interaction between them might participate in the initiation and development of epithelial-mesenchymal transition in pancreatic cancer.

Analysis of the association between plasma PCSK9 and Lp(a) in Han Chinese

PURPOSE

It has been reported that proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors can significantly reduce lipoprotein(a) [Lp(a)], and the mechanism for Lp(a) reduction remains unclear. Recently an interesting clinical research with a small sample showed a positive correlation between plasma PCSK9 and Lp(a) levels in diabetes. Here we aimed to use a relatively large sample to investigate whether such an association exists in Han Chinese.

METHODS

A total of 783 inpatients were consecutively enrolled and composed of 172 patients with type 2 diabetes mellitus (T2DM) and 611 non-T2DM subjects. Plasma PCSK9 level was measured by ELISA, and its association with Lp(a) was assayed by Spearman's correlation and multiple regression. Clinical and biochemical parameters were determined in all subjects studied.

RESULTS

No significant differences in PCSK9 and Lp(a) levels were found between T2DM and non-T2DM patients. PCSK9 level was not related to Lp(a) level either in T2DM or non-T2DM group in bivariate correlation and multiple linear regression analysis. Additionally, no association between the levels of PCSK9 and Lp(a) was found in well, poorly controlled T2DM patients or in T2DM patients with or without coronary artery disease (CAD). Besides, no difference was found among the PCSK9 values across tertiles of Lp(a) level.

CONCLUSION

We found no association of plasma PCSK9 levels with Lp(a) level in Han Chinese with or without T2DM, suggesting that Lp(a) reduction by PCSK9 inhibitors may not be achieved simply through PCSK9 pathway at least in Chinese.