Fabrication of silver tips for scanning tunneling microscope induced luminescence

We describe a reliable fabrication procedure of silver tips for scanning tunneling microscope (STM) induced luminescence experiments. The tip was first etched electrochemically to yield a sharp cone shape using selected electrolyte solutions and then sputter cleaned in ultrahigh vacuum to remove surface oxidation. The tip status, in particular the tip induced plasmon mode and its emission intensity, can be further tuned through field emission and voltage pulse. The quality of silver tips thus fabricated not only offers atomically resolved STM imaging, but more importantly, also allows us to perform challenging "color" photon mapping with emission spectra taken at each pixel simultaneously during the STM scan under relatively small tunnel currents and relatively short exposure time.

Recycled cafeteria food waste as a feed for swine: nutrient content digestibility, growth, and meat quality

This project was undertaken to compare growth, meat quality, and diet digestibility when pigs were fed cafeteria food waste (FW) or a corn/soybean meal (CSM) diet. Cafeteria food waste (36 samples) fed in the growing and finishing experiment averaged 22.4% DM, 21.4% CP, 14.1% ADF, 27.2% ether extract, and 3.2% ash. The first experiment used 50 crossbred pigs randomly assigned to four diets. During the growing phase, pigs fed a CSM diet gained faster (P < .05) than pigs fed FW or FW plus energy supplements. However, the two groups fed FW plus energy supplements (at 25 or 50% of the intake of the CSM diet) gained faster (P < .05) than pigs fed FW alone (.61 and .65 kg/d, respectively, vs .46 kg/d). In the finishing phase, FW plus an energy supplement fed at 50% of the level of CSM intake resulted in gains that did not differ from those of pigs fed the CSM diet (.90 vs .99 kg/d; P > .05). A nutrient digestibility and nitrogen balance trial using eight growing barrows compared FW with the same CSM growing diet fed earlier. Dry matter digestibility was similar for the two diets (P > .05). However, CP digestibility was higher (P < .05) in the FW diet than in the CSM diet (88.2 vs 84.3%). Although the percentage of nitrogen retained was not different between FW and CSM diets (56.0 vs 55.2%; P > .05), the amount of nitrogen retained was greater for pigs fed the CSM diet (29.3 vs. 24.5 g/d; P < .05) because DMI was greater (1.7 vs 1.4 kg/d) for pigs fed CSM compared with FW. At the completion of the finishing experiment, six pigs were selected from both the CSM and FW diets and fed to finishing weight. The pigs were slaughtered, and the pork loins were removed for flavor and texture analysis. A consumer panel rated the meat quality from FW pigs as acceptable and overall flavor comparable to CSM pigs (P > .05). These results indicate that food waste has nutritive value and may be useful in swine diets.

Relationships among KRAS mutation status, expression of RAS pathway signaling molecules, and clinicopathological features and prognosis of patients with colorectal cancer

BACKGROUND

The RAS/RAF/MEK/ERK and PI3K/AKT/mTOR signaling pathways all belong to mitogen-activated protein kinase (MAPK) signaling pathways, Mutations in any one of the upstream genes (such as the RAS gene or the BRAF gene) may be transmitted to the protein through transcription or translation, resulting in abnormal activation of the signaling pathway. This study investigated the relationship between the KRAS gene mutation and the clinicopathological features and prognosis of colorectal cancer (CRC), and the effect of KRAS mutations on its associated proteins in CRC, with an aim to clarify the cause of tumor progression and drug resistance caused by mutation of the KRAS gene.

AIM

To investigate the KRAS gene and RAS pathway signaling molecules in CRC and to analyze their relationship with clinicopathological features and prognosis

METHODS

Colorectal cancer tissue specimens from 196 patients were analyzed for KRAS mutations using quantitative polymerase chain reaction and for KRAS, BRAF, MEK, and ERK protein expression levels using immunohistochemistry of tumor microarrays. To analyze differences of RAS pathway signaling molecule expression levels in different KRAS gene status, the relationships between these parameters and clinicopathological features, 4-year progression-free survival, and overall survival were analyzed by independent sample t test, Kaplan-Meier plots, and the log-rank test. Predictors of overall and disease-free survival were assessed using a Cox proportional hazards model.

RESULTS

Of the 196 patients, 62 (32%) carried mutations in codon 12 (53/62) or codon 13 (9/62) in exon 2 of the KRAS gene. KRAS, BRAF, ERK, and MEK protein expression was detected in 71.4%, 78.8%, 64.3%, and 50.8% of CRC tissues, respectively. There were no significant differences between KRAS mutation status and KRAS, BRAF, MEK, or ERK protein levels. Positive expression of KRAS and ERK was associated with poor tumor differentiation, and KRAS expression was also associated with age < 56 years. MEK expression was significantly associated with distant metastasis (P < 0.05). The 4-year progression-free survival rate, but not overall survival rate, was significantly higher in patients with KRAS-negative tumors than in those with KRAS-positive tumors (P < 0.05), whereas BRAF, MEK, and ERK expression was unrelated to survival. Multivariate analysis showed that only the expression of KRAS protein was a risk factor for tumor recurrence (P < 0.05). No other clinicopathological factors correlated with KRAS, BRAF, MEK, or ERK expression.

CONCLUSION

KRAS gene mutations do not affect downstream protein expression in CRC. KRAS protein is associated with poor tumor differentiation, older age, and a risk of tumor recurrence.

A new method to induce molecular low bias negative differential resistance with multi-peaks

According to a first-principles study of the transport properties of two thiolated anthracene-9,10-diono molecules sandwiching ethyl, a new method to induce molecular low bias negative differential resistance with multi-peaks for strong n- or p-type molecules is proposed. The anthracene-9,10-diono molecule shows strong n-type characteristics when in contact with Au and Ag electrodes via a thiolate. The multiple negative differential resistance effect originated from the molecule-electrode couple is different between Ag and Au electrodes. Our investigations may promise potential for applications in molecular devices with low power dissipation and multifunction in the future.

Note: optical optimization for ultrasensitive photon mapping with submolecular resolution by scanning tunneling microscope induced luminescence

We report the development of a custom scanning tunneling microscope equipped with photon collection and detection systems. The optical optimization includes the comprehensive design of aspherical lens for light collimation and condensing, the sophisticated piezo stages for in situ lens adjustment inside ultrahigh vacuum, and the fiber-free coupling of collected photons directly onto the ultrasensitive single-photon detectors. We also demonstrate submolecular photon mapping for the molecular islands of porphyrin on Ag(111) under small tunneling currents down to 10 pA and short exposure time down to 1.2 ms/pixel. A high quantum efficiency up to 10(-2) was also observed.

[A cross-sectional study on psychological needs of family members of critically ill inpatients in semi-closed wards and analysis of influence factors]

Objective: To analyze and discuss the psychological needs of family members of critically ill burn inpatients in semi-closed wards and their related influence factors. Methods: A cross-sectional survey was conducted among the 82 burn patients, who met the inclusion criteria and were admitted to the Department of Burns and Plastic Surgery of Ruijin Hospital of Shanghai Jiao Tong University School of Medicine from October 2018 to April 2019, and their family members. A general condition questionnaire of 15 indexes was applied to investigate the general data of burn patients and their family members including cause of burn, gender, age, total burn area, burn depth, burn severity, burn site, and type of medical insurance of patients, kinship with the patients, gender, age, experience of accompanying in intensive care isolation wards, occupation, education level, and monthly income of their family members. The Critical Care Family Needs Inventory (CCFNI) was used to assess each item, each factor, and total scores of the family members of patients including 5 factors and 45 items such as support scale (SS), comfort scale (CS), information scale (IS), proximity scale (PS), assurance scale (AS). CCFNI was used to assess the total scores of patients and their family members after classification according to the general data, the data were statistically analyzed with one-way analysis of variance or independent sample t test. Indicators with statistical significance in the above analysis were selected for multiple linear regression analysis to screen the independent influence factors of psychological needs of patients' family members. CCFNI was used to assess each dimension scores of patients and their family members after classification according to the aforementioned selected independent influence factors including age and burn area of patients, gender, educational level, and experience of accompanying in intensive care isolation wards of their family members, and the data were statistically analyzed with one-way analysis of variance or independent sample t test. Results: A total of 82 questionnaires were sent out in this study, and 80 were effectively received, with s a recovery rate of 97.6%. In 80 patients, there were 45 males and 35 females; 35 cases (43.75%) were ≤14 years; most of the patients had flame and thermal burns; 33 patients (41.25%), 21 patients (26.25%), and 26 patients (32.50%) had moderate, severe, and extremely severe burns, respectively; and only 3 patients (3.75%) had no health insurance. In 80 family members of patients, 34 (42.50%) were males and 46 (57.50%) were females; 62.50% in the family members of patients were concentrated between 18 and 45 years old; and 12 family members of patients had experience of accompanying in intensive care isolation wards, accounting for 15.00%. The total CCFNI score of the family members was (141±14) points, and the scores of AS, PS, IS, CS, and SS were (3.77±0.23), (3.43±0.37), (3.53±0.34), (2.50±0.59), and (2.69±0.45) points, respectively. The top five items of the psychological needs of family members of patients were concentrated in three factors (AS, PS, and IS), and the item "ensuring that patients receive the best treatment" ranked the first, with a score of (3.99±0.11) points. There were significant differences on the CCFNI total scores of patients with different age, total burns area, and severity of burns and of their family members with different gender, education level, and whether or not experience of accompanying in intensive care isolation unit (F=4.378, 5.481, 5.913, t=4.027, 14.339, 7.265, P<0.05 or P<0.01). Multiple linear regression analysis showed that the patient's age (≤14, 15-45 years) and total burn area (11%-30%, 31%-49%, ≥50% TBSA) and the patient's family members' gender, educational level, experience of accompanying in intensive care isolation unit could affect the psychological needs of family members of patients (t=3.133, 2.260, 2.297, 2.433, 3.015, 2.200, 2.102, 2.463, P<0.05 or P<0.01). There was statistically significant difference in AS score of the patients' family members with different age (F=4.390, P<0.05). There were significant differences in both IS and AS scores of the patients' family members of patients with different burn area (F=5.042, 3.131, P<0.05 or P<0.01). The AS score of the patients' family members with experience of accompanying in intensive care isolation unit was significantly lower than those without (t=-1.040, P<0.05). The SS score of the patients' family members with college education or above was significantly higher than those with high school (technical secondary school) or below (t=0.657, P<0.05). The IS score of the patients' family members with college education or above was significantly lower than those with high school (technical secondary school) or below (t=-1.438, P<0.05). The SS score of male family members of patients was significantly lower than those of female patients (t=4.149, P<0.05). Conclusions: The family members of burn patients in semi-closed ward have the most urgent need to ensure the patients receive the best treatment. Patients' age, total burn area, and their family members' gender, education level, experience of accompanying in intensive care isolation unit are the main factors affecting the psychological needs of family members of patients.

[Levels of sgRNA as a Major Factor Affecting CRISPRi Knockdown Efficiency in K562 Cells]

To determine how nuclease deactivated Cas9 (dCas9) or single-guide RNA (sgRNA) expression levels affect the knockdown efficiency of CRISPRi, we created K562 cell clones expressing KRAB-dCas9 protein either with the inducible Tet-on system or with the constitutive SFFV promotor. Single clones were selected by fluorescence-activated cell sorting (FACS) for further study. Six genes with various expression levels were targeted using lentiviral sgRNA from two libraries in four cell clones with various KRAB-dCas9 expression levels. The expression level of dCas9 protein/sgRNA levels and the knockdown efficiency were determined by flow cytometry. The cell clone with the highest KRAB-dCas9 expression level achieved effective CRISPRi knockdown. The data describing this clone were statistically different from that on other clones, indicating the strong KRAB-dCas9 expression might be a prerequisite for CRISPRi. By adopting different multiplicity of infection (MOI) in lentiviral transduction of this clone, we modified the expression level of sgRNA and found that the knockdown efficiency was neither affected by the target gene expression level nor correlated with KRAB-dCas9 levels, which remained relatively constant across all knockdown experiments (coefficient of variation = 2.2%). As an example, the following levels of the knockdowns: 74.72, 72.28 and 39.08% for mmadhc, rpia and znf148 genes, respectively, were achieved. These knockdown efficiencies correlated well with the respective sgRNA expression levels. Linear regression models built using this data indicate that the knockdown efficiency may be significantly affected by the levels of both KRAB-dCas9 and sgRNA. Notably, the sgRNA levels have greater impact, being a major factor affecting CRISPRi efficiency.

[Study on the dynamic changes of peripheral platelet-to-lymphocyte ratio in the prognosis of neoadjuvant chemotherapy patients with gastric cancer]

Objective: To investigate the significance of platelet lymphocyte ratio (PLR) before and after neoadjuvant chemotherapy in advanced gastric cancer (AGC). Methods: The medical records of 247 AGC patients who underwent surgery between May 2015 and October 2016 were retrospectively reviewed. The relationship between PLR value and its changes before and after neoadjuvant therapy and clinicopathological features and prognosis was further analyzed. Results: △PLR was defined according to the different states of PLR before and after neoadjuvant therapy. If negative value was defined as"Reduced Group"(138) and positive value or 0 was defined as "Unreduced group"(109). There were statistical differences between the two groups of△PLR in tumor size, nerve invasion, presence or absence of vascular tumor thrombus, ypT staging, ypN staging, ypTNM staging, and pathological response (all P<0.05), but there was no statistical difference between age, gender, and postoperative adjuvant chemotherapy (all P>0.05). Survival analysis showed that the 5-year disease-free survival rates between the two groups were 39.0% and 54.0%, respectively (P=0.025); the 5-year overall survival rates between the two groups were 41.8% and 58.1%, respectively (P=0.035); the difference were statistically significant. Multivariate analysis showed that ypT3-4 stage, ypN3b stage and △PLR were independent risk factors for 5-year disease-free survival rate (HR=2.731/2.676, 95%CI: 1.026-7.268/1.014-6.985; HR=4.717, 95%CI: 1.922-11.579; HR=2.854, 95%CI: 1.117-4.124; all P<0.05) and 5-year overall survival rate (HR=3.226/2.655, 95%CI: 1.280-9.227/0.945-7.548; HR=4.550, 95%CI: 1.842-11.239; HR=2.897, 95%CI: 1.049-5.251; all P<0. 05). Conclusion: △PLR can better predict the prognosis of AGC patients receiving neoadjuvant chemotherapy.