High-throughput sorting of nanoparticles with light-patterned dielectrophoresis force.

We present a size-based sorting method for nanoparticles in microfluidics with the aid of light-patterned dielectrophoresis (DEP) force. In a microfluidic channel, we have succeeded in manipulating a random distribution of particles into a single stream with the DEP force as well as the hydrodynamic force, and more strikingly, the trajectory of particles is found to be size-dependent, implicating that we can precisely separate nanoparticles based on their sizes even if they are identical in mass. We have numerically predicted the behavior of sorting nanoparticles, emphasizing on the size, velocity and electrical permittivity, so as to know their influences on the effective sorting, particularly in terms of high throughput. Our work confirms that what we believe to be the novel manipulation of nanoparticles features its flexibility as well as high throughput.

Screening and identification of genes involved in ß-alanine biosynthesis in Bacillus subtilis.

ß-alanine is the only naturally occurring ß-amino acid, which is widely used in medicine, food, and feed fields, and generally produced through synthetic biological methods based on engineered strains of Escherichia coli or Corynebacterium glutamicum. However, the ß-alanine biosynthesis in Bacillus subtilis, a traditional industrial model microorganism of food safety grade, has not been thoroughly explored. In this study, the native l-aspartate-α-decarboxylase was overexpressed in B. subtilis 168 to obtain an increase of 842% in ß-alanine production. A total of 16 single-gene knockout strains were constructed to block the competitive consumption pathways to identify a total of 6 genes (i.e., ptsG, fbp, ydaP, yhfS, mmgA, and pckA) involved in ß-alanine synthesis, while the multigene knockout of these 6 genes obtained an increased ß-alanine production by 40.1%. Ten single-gene suppression strains with the competitive metabolic pathways inhibited revealed that the inhibited expressions of genes glmS, accB, and accA enhanced the ß-alanine production. The introduction of heterologous phosphoenolpyruvate carboxylase increased the ß-alanine production by 81.7%, which was 17-fold higher than that of the original strain. This was the first study using multiple molecular strategies to investigate the biosynthetic pathway of ß-alanine in B. subtilis and to identify the genetic factors limiting the excessive synthesis of ß-alanine by microorganisms.

Improved biosynthesis of heme in Bacillus subtilis through metabolic engineering assisted fed-batch fermentation.

BACKGROUND: Heme is an iron/porphyrin complex compound, widely used in the health care, food, and pharmaceutical industries. It is more advantageous and attractive to develop microbial cell factories to produce heme by fermentation, with lower production costs and environmentally more friendly procedures than those of the traditional extraction based on animal blood. In this study, Bacillus subtilis, a typical industrial model microorganism of food safety grade, was used for the first time as the host to synthesize heme. RESULTS: The heme biosynthetic pathway was engineered as four modules, the endogenous C5 pathway, the heterologous C4 pathway, the uroporphyrinogen (urogen) III synthesis pathway, and the downstream synthesis pathway. Knockout of hemX encoding the negative effector of the concentration of HemA, overexpression of hemA encoding glutamyl-tRNA reductase, and knockout of rocG encoding the major glutamate dehydrogenase in the C5 pathway, resulted in an increase of 427% in heme production. Introduction of the heterologous C4 pathway showed a negligible effect on heme biosynthesis. Overexpression of hemCDB, which encoded hydroxymethylbilane synthase, urogen III synthase, and porphobilinogen synthase participating in the urogen III synthesis pathway, increased heme production by 39%. Knockouts of uroporphyrinogen methyltransferase gene nasF and both heme monooxygenase genes hmoA and hmoB in the downstream synthesis pathway increased heme production by 52%. The engineered B. subtilis produced 248.26 ± 6.97 mg/L of total heme with 221.83 ± 4.71 mg/L of extracellular heme during the fed-batch fermentation in 10 L fermenter. CONCLUSIONS: Strengthening endogenous C5 pathway, urogen III synthesis pathway and downstream synthesis pathway promoted the biosynthesis of heme in B. subtilis. The engineered B. subtilis strain has great potential as a microbial cell factory for efficient industrial heme production.

[Association Between Plasma Adiponectin and Risk of Breast Cancer by Molecular Subtypes].

OBJECTIVE: To explore the relationships between plasma adiponectin levels and risk of breast cancer by molecular subtype. METHODS: A case-control study including 437 histopathologic confirmed primary breast cancer cases and 469 healthy female controls was conducted between April 2014 and May 2015. Basic information of the participants were collected using a structured questionnaire. Blood samples were collected and the plasma adiponectin levels were measured by enzyme-linked immunosorbent assay (ELASA). Analysis of variance (ANOVA) was used to compare the differences of plasma adiponectin levels among the control group and the breast cancer groups with different molecular subtypes. Multinomial logistic regression was used to investigate the association between plasma adiponectin levels and risk of breast cancer by molecular subtypes. All the statistical analyses were stratified by menopausal status. RESULTS: Among the 437 breast cancer cases, there were 310 Luminal breast cancer cases, 83 HER-2-enriched breast cancer cases and 44 basal-like breast cancer cases. The median (P25, P75) of plasma adiponectin level of the controls was 14.85 (9.69, 21.35) µg/mL. The medians (P25, P75) of plasma adiponectin levels of the cases were 11.74 (8.15, 16.14) µg/mL, 12.02(8.43, 16.96) µg/mL and 12.67(8.25, 17.27) µg/mL for Luminal, HER-2-enriched and basal-like subtype respectively, which were statistically different from the controls (P < 0.001). Multinomial logistic regression showed that, after adjustment for the confounders, the higher levels of plasma adiponectin were associated with the lower risks of pre-menopausal Luminal breast cancer (ORpre-menopausal Luminal=0.50, 95%CI: 0.27-0.92, Ptrend=0.001), post-menopausal Luminal breast cancer (ORpost-menopausal Luminal=0.06, 95%CI: 0.02-0.23, Ptrend < 0.001) and post-menopausal HER-2-enriched breast cancer (ORpost-menopausal HER-2-enriched=0.06, 95%CI: 0.01-0.62, Ptrend=0.001). CONCLUSION: Lower levels of plasma adiponectin may increase the risk of pre-menopausal and post-menopausal Luminal breast cancer and post-menopausal HER-2-enriched breast cancer.

Nd3+-Sensitized Upconversion Nanostructure as a Dual-Channel Emitting Optical Probe for Near Infrared-to-Near Infrared Fingerprint Imaging.

Lanthanide upconversion nanophosphors (Ln-UCNPs) have attracted great attention in a variety of fields, benefiting from low background fluorescence interference and a high signal-to-noise ratio of upconversion luminescence. However, the establishment of Ln-UCNPs with dual near-infrared (NIR) emission channels still remains challenging. Herein, we report the design and synthesis of Nd3+-sensitized NaYbF4:Tm@NaYF4:Yb@NaNdF4:Yb hierarchical-structured nanoparticles that emit NIR luminescence at 696 and 980 nm under excitation at 808 nm. The sensitizer-rich NaYbF4 core promotes efficient energy transfer to Tm3+. The interlayer of NaYF4:Yb effectively prevents the cross-relaxation process from Tm3+ to Nd3+ and thus enhances the luminescence emission. The introduction of Nd3+ ion as the sensitizer transforms the excitation wavelength from 980 to 808 nm, which subtly averts the laser-induced thermal effect and offers a new pathway for the NIR emission channel at 980 nm. The as-prepared nanoparticles were further applied in developing latent and blood fingerprint images, which exhibited high signal-to-noise ratio and distinguishable details under 808 nm excitation with negligible thermal damage to the sample. Our work provides a promising strategy to realize NIR-to-NIR dual-channel emissions in Ln-UCNPs. With further functionalization, such nanoparticles are expected to have great potential in forensic and biological sciences.

Ultrasensitive near-infrared fluorescence-enhanced probe for in vivo nitroreductase imaging.

Nitroreductase (NTR) can be overexpressed in hypoxic tumors, thus the selective and efficient detection of NTR is of great importance. To date, although a few optical methods have been reported for the detection of NTR in solution, an effective optical probe for NTR monitoring in vivo is still lacking. Therefore, it is necessary to develop a near-infrared (NIR) fluorescent detection probe for NTR. In this study, five NIR cyanine dyes with fluorescence reporting structure decorated with different nitro aromatic groups, Cy7-1-5, have been designed and explored for possible rapid detection of NTR. Our experimental results presented that only a para-nitro benzoate group modified cyanine probe (Cy7-1) could serve as a rapid NIR fluorescence-enhanced probe for monitoring and bioimaging of NTR. The structure-function relationship has been revealed by theoretical study. The linker connecting the detecting and fluorescence reporting groups and the nitro group position is a key factor for the formation of hydrogen bonds and spatial structure match, inducing the NTR catalytic ability enhancement. The in vitro response and mechanism of the enzyme-catalyzed reduction of Cy7-1 have been investigated through kinetic optical studies and other methods. The results have indicated that an electro-withdrawing group induced electron-transfer process becomes blocked when Cy7-1 is catalytically reduced to Cy7-NH2 by NTR, which is manifested in enhanced fluorescence intensity during the detection process. Confocal fluorescence imaging of hypoxic A549 cells has confirmed the NTR detection ability of Cy7-1 at the cellular level. Importantly, Cy7-1 can detect tumor hypoxia in a murine hypoxic tumor model, showing a rapid and significant enhancement of its NIR fluorescence characteristics suitable for fluorescence bioimaging. This method may potentially be used for tumor hypoxia diagnosis.

Protective effect of pranlukast on Aß1₋42-induced cognitive deficits associated with downregulation of cysteinyl leukotriene receptor 1.

Deposition of extracellular amyloid-ß (Aß) peptide is one of the pathological hallmarks of Alzheimer's disease (AD). Accumulation of Aß is thought to associate with cognition deficits, neuroinflammation and apoptosis observed in AD. However, effective neuroprotective approaches against Aß neurotoxicity are unavailable. In the present study, we analysed the effects of pranlukast, a selective cysteinyl leukotriene receptor 1 (CysLT1R) antagonist, on the impairment of learning and memory formation induced by Aß and the probable underlying electrophysiological and molecular mechanisms. We found that bilateral intrahippocampal injection of Aß1₋42 resulted in a significant decline of spatial learning and memory of mice in the Morris water maze (MWM) and Y-maze tests, together with a serious depression of in vivo hippocampal long-term potentiation (LTP) in the CA1 region of the mice. Importantly, this treatment caused significant increases in CysLT1R expression and subsequent NF-κB signaling, caspase-3 activation and Bcl-2 downregulation in the hippocampus or prefrontal cortex. Oral administration of pranlukast at 0.4 or 0.8 mg/kg for 4 wk significantly reversed Aß1₋42-induced impairments of cognitive function and hippocampal LTP in mice. Furthermore, pranlukast reversed Aß1₋42-induced CysLT1R upregulation, and markedly suppressed the Aß1₋42-triggered NF-κB pathway, caspase-3 activation and Bcl-2 downregulation in the hippocampus and prefrontal cortex in mice. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay confirmed its presence in the brain after oral administration of pranlukast in mice. These data disclose novel findings about the therapeutic potential of pranlukast, revealing a previously unknown therapeutic possibility to treat memory deficits associated with AD.

An Evaluation Index System for Research Efficiency of Research-Oriented Hospitals in China.

A specific and rational index system is key to scientific research evaluation. According to the characteristics and status of research-oriented hospitals in China, this study aimed to construct a comprehensive and methodical system for scientific research evaluation. Using bibliometric research, we sorted and refined indices for both domestic and international scientific research evaluation systems, established two-dimensional indices of input and output, and constructed the theoretical framework of evaluation after experts. The Delphi method was adopted to determine the evaluation indices at all levels, and the Analytic Hierarchy Process was used to calculate the weights of the indices at all levels. Twenty experts from different medical fields were involved in the 2 rounds study. Altogether, 7 primary, 14 secondary, and 37 tertiary indices were included in the evaluation system. A matrix was built to conduct the maximum eigenvalue, the consistency indices, and the consistency ratio of each expert in the survey. The index weight coefficients of the indices were calculated accordingly. The model exhibited high consistency, and the credibility of the results was verified. The evaluation system for research-oriented hospitals that we established had high specificity, credibility, and rationality. The evaluation system that we established combines some quantitative evaluation indicators, which are subsequently weighted according to their importance in the field of research-oriented hospital. Evaluation index system will provide the practical manner in the future for comparing the potential academic level and impact of research-oriented hospitals. Moreover, further verification, adjustments, and optimization of the system and indicators will be performed in follow-up empirical studies.

Factors associated with the research efficiency of clinical specialties in a research-oriented hospital in China.

Research-oriented hospitals are responsible for medical services tasks, medical education, and scientific research, playing an important role in medical research and application. The research efficiency of a clinical specialty is influenced by factors such as the characteristics of the specialty, the organizational atmosphere, and the clinical director's leadership. The present study aimed to describe the research efficiency of clinical specialties, explore the factors influencing it, and clarify the argument of co-evolution theory regarding the collaborative development of medical services, education, and research. Logistic regression and multiple linear regression were adopted to estimate the correlation between influencing factors and scientific research efficiency. Hospital H, which is representative of research hospitals in China, was taken as an example. Taking three efficiency values-comprehensive technical efficiency (CTE), pure technical efficiency (PTE), and scale efficiency (SE)-as dependent variables, the independent variables affecting research productivity were statistically analyzed. This study also examined the scientific research efficiency of 41 specialties between 2013 and 2017, and found that the independent variables affected CTE, PTE, and SE to various degrees. Collaborative innovation in medical education and research must be based on clinical research; how to balance medical and teaching quality, and research efficiency requires further discussion. While young people play a major role on the research team because of their creativity and initiatives, which improve CTE and PTE, high-level researchers with better research and leadership abilities lead to the rational allocation and effective utilization of resources, thus improving SE. In 2013-2017, discipline construction focused on scale expansion, resulting in the decline of SE in China. Therefore, this study suggests further improvements for the efficiency of clinical specialties in research hospitals.

Upconversion nanocomposite for programming combination cancer therapy by precise control of microscopic temperature.

Combinational administration of chemotherapy (CT) and photothermal therapy (PTT) has been widely used to treat cancer. However, the scheduling of CT and PTT and how it will affect the therapeutic efficacy has not been thoroughly investigated. The challenge is to realize the sequence control of these two therapeutic modes. Herein, we design a temperature sensitive upconversion nanocomposite for CT-PTT combination therapy. By monitoring the microscopic temperature of the nanocomposite with upconversion luminescence, photothermal effect can be adjusted to achieve thermally triggered combination therapy with a sequence of CT, followed by PTT. We find that CT administered before PTT results in better therapeutic effect than other administration sequences when the dosages of chemodrug and heat are kept at the same level. This work proposes a programmed method to arrange the process of combination cancer therapy, which takes full advantage of each therapeutic mode and contributes to the development of new cancer therapy strategies.