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2.
Clin Rheumatol ; 2021 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-33677723

RESUMO

OBJECTIVE: This study aimed to identify osteoarthritis (OA) related genes based on microarray data in synovium with a more robust integrative analysis method. METHODS: Four series GSE55457, GSE12021, GSE55235, and GSE55584 (36 OA and 29 normal samples) were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) of GSE55457, GSE12021, and GSE55235 were identified using the LIMMA package. Overlapping DEGs from the intersection of the three series were detected. Simultaneously, samples in the four series were pooled to identify DEGs with integrated analysis using the Sva package. RESULTS: In total, 74 overlapping DEGs and 242 DEGs by integrating four series were detected. Based on them, 70 common DEGs were used to construct a protein-protein interaction (PPI) network, involving 61 nodes and 206 edges. Also, three gene modules and five hub genes, named JUN, IL6, VEGFA, MYC, and EGR1, were identified. CONCLUSIONS: Seventy DEGs were finally identified with a more robust integrative analysis method. JUN, IL6, VEGFA, MYC, and EGR1 were identified as hub genes in the development of OA. Key Points • 76 overlapping DEGs were detected from the intersection of DEGs in GSE55457, GSE12021, and GSE55235. • 242 DEGs were identified by integrating four series using Sva package. • 72 common DEGs were finally identified based on the overlapping DEGs and the integrated DEGs. • JUN, IL6, VEGFA, MYC, and EGR1 were identified as hub genes in the development of OA.

3.
BMC Cancer ; 21(1): 278, 2021 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-33726698

RESUMO

BACKGROUND: Hepatocellular carcinoma (HCC) is a common malignant tumor with a poor prognosis. We aimed to identify a new prognostic model of HCC based on differentially expressed (DE) immune genes. METHODS: The DE immune genes were identified based on an analysis of 374 cases of HCC and 50 adjacent non-tumor specimens from the Cancer Genome Atlas (TCGA) database. Univariate Cox analysis, Lasso regression, and multivariate Cox analysis were used to construct the model based on the training group. Survival analysis and the receiver operating characteristic (ROC) curves were used to evaluate model performance. The testing group and the entire group were subsequently used for validation of the model. RESULTS: A five-immune gene model consisted of HSPA4, ISG20L2, NDRG1, EGF, and IL17D was identified. Based on the model, the overall survival was significantly different between the high-risk and low-risk groups (P = 7.953e-06). The AUCs for the model at 1- and 3-year were 0.849 and 0.74, respectively. The reliability of the model was confirmed using the validation groups. The risk score was identified as an independent prognostic parameter and closely related to the content of immune cells from human HCC specimens. CONCLUSION: We identified a five-immune gene model that can be used as an independent prognostic marker for HCC.

4.
Biochem Pharmacol ; 185: 114414, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33434537

RESUMO

Dexamethasone is a common synthetic glucocorticoid drug that can promote foetal lung maturity. An increasing number of studies have shown that prenatal dexamethasone exposure (PDE) can cause a variety of short-term and long-term hazards to offspring, including bone development toxicity. H-type vessels are a newly discovered subtype of blood vessels associated with promoted bone formation and maintenance of bone mass. In this study, we aimed to explore whether H-type blood vessels are involved in PDE-induced long bone development toxicity in offspring and its mechanism. In vivo, we injected dexamethasone (0.2 mg/kg.d) subcutaneously at gestational days 9-20 and observed the H-type vessel abundance and bone mass at different time points in the offspring rats. In vitro, we investigated the effect of dexamethasone (0, 20, 100, and 500 nM) on the tube formation function of rat bone marrow-derived endothelial progenitor cells (EPCs) and explored its mechanism. Our results showed that the adult PDE female offspring rats were susceptible to osteoporosis. In addition, PDE inhibited bone mass, H-type vessel formation and the expression of bone platelet-derived growth factor receptor ß (PDGFRß)/focal adhesion kinase (FAK) pathway-related genes in antenatal and postnatal female offspring. Moreover, PDE promoted the expression of bone glucocorticoid receptor (GR), CCAAT and enhancer binding protein α (C/EBPα) and miR-34c in female foetuses. Dexamethasone suppressed the tube formation of rat bone marrow-derived EPCs and the activity of the PDGFRß/FAK pathway, which was mediated by GR/C/EBPα/miR-34c signalling activation. In summary, PDE can cause H-type vessel dysplasia and high susceptibility to osteoporosis in female offspring, and its mechanism is related to the low-activity programming of the PDGFRß/FAK pathway induced by GR/C/EBPα/miR-34c signalling activation. This study enhances the understanding of the molecular mechanism of dexamethasone-induced bone development toxicity and provides new insights for exploring the early intervention and therapeutic targets of foetal-derived osteoporosis.

5.
Hum Cell ; 34(2): 550-563, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33389678

RESUMO

PIWI (P element induced wimpy testis) integrating RNAs (piRNAs) are small non-coding RNAs with the length of approximately 30 nucleotides that plays crucial roles in germ cells and adult stem cells. Recently, accumulating data have shown that piRNA and PIWI proteins are involved in tumorigenesis. However, the roles of PIWI proteins and piRNAs in pancreatic cancer are still elusive. Here, we showed that piR-017061 is significantly downregulated in pancreatic cancer patients' samples and pancreatic cancer cell lines. Furthermore, we studied the function of piR-017061 in pancreatic cancer and our data revealed that piR-017061 inhibits pancreatic cancer cell growth in vitro and in vivo. Moreover, we analyzed the genomic loci around piR-017061 and identified EFNA5 as a novel target of piR-017061. Importantly, our data further revealed a direct binding between piR-017061 and EFNA5 mRNA mediated by PIWIL1. Mechanically, piR-017061 cooperates with PIWIL1 to facilitate EFNA5 mRNA degradation and loss of piR-017061 results in accumulation of EFNA5 which facilitates pancreatic cancer development. Hence, our data provided novel insights into PIWI/piRNA-mediated gene regulation and their function in pancreatic cancer. Since PIWI proteins and piRNA predominately express in germline and cancer cells, our study provided novel therapeutic strategy for pancreatic cancer treatment.

6.
Molecules ; 26(3)2021 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-33494212

RESUMO

The glutenin macropolymer (GMP), which is an important component of the glutenin protein in wheat flour, plays a prominent role in governing dough properties and breadmaking quality. This study investigated the changes in GMP properties during the mixing and resting stages of dough processing. The results show that the GMP content decreases by about 20.20% when the mixing time increases from 3 to 5 min, while increasing the resting time can lead to restoration of some GMP contents. Resting promotes greater formation of large-sized GMP particles, which is likely related to the increased disulfide bond content in the GMP during this process. In contrast, the mechanical force of mixing causes GMP depolymerization and formation of smaller particles. Furthermore, after mixing, the protein secondary structure tends to be disordered, the protein morphology becomes irregular, and the protein subunit ratio changes. Thus, mixing has many of the opposite effects to resting, although resting can (to some extent) restore the properties of the GMP after mixing. However, excessive resting time can lead to negative results, reflected in lower disulfide bond (SS) and GMP contents, and more irregular particle sizes. The presented results suggest that dough mixing induces rearrangement of the dough's protein structure, and resting somewhat restores the chemical bonds and internal protein structure.

7.
Food Chem ; 338: 127838, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-32822905

RESUMO

The potent aroma compounds in butter from four kinds of Chinese butter hotpot seasoning were first investigated by analyzing the isolates from solid-phase microextraction. A total of 49 aroma compounds were identified, and 23 of them were highly correlated with the aroma profiles of the butter by partial least squares regression analysis. Aroma extract dilution analysis and odor activity value calculations were applied to further reveal the dominant odorants. Fifty-three odorants with flavor dilution factors between 1 and 1024 were identified and OAVs of 17 odorants were greater than 1. Finally, an aroma recombination experiment was prepared by mixing the aroma-active compounds (OAVs > 1), and the aroma profile of the recombination showed good agreement with that of the original sample. Omission tests showed that 2-furfurylthiol, 2-acetylthiazole, anethole, (E)-2-decenal, and 1,8-cineole were the key odorants for the overall aroma of butter.


Assuntos
Manteiga , Odorantes/análise , Compostos Orgânicos Voláteis/análise , Manteiga/análise , Eucaliptol/análise , Análise de Alimentos/métodos , Análise de Alimentos/estatística & dados numéricos , Furanos/análise , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Análise dos Mínimos Quadrados , Olfatometria , Microextração em Fase Sólida , Especiarias , Compostos de Sulfidrila/análise
10.
Med Sci Monit ; 26: e927392, 2020 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-33275591

RESUMO

BACKGROUND We constructed a predictive risk model of esophageal carcinoma (EC) for prognostic prediction. MATERIAL AND METHODS Immune genes and the expression data were downloaded from the ImmPort database and The Cancer Genome Atlas database. Univariate analysis, Lasso regression, and multivariate analysis were applied to screen the ultimately included prognostic immune genes for the model based on the training cohort. Survival analysis and receiver operating characteristic (ROC) curve were applied to evaluate the model. The model was further validated in the testing and entire cohorts, and the clinical utility of the model and its ability to assess the subtypes of EC were evaluated in the entire cohort. RESULTS We detected 297 differentially expressed immune genes, including 241 upregulated genes and 56 downregulated genes in EC patients. Based on these genes, we developed a 7-immune gene model of EC, including HSPA6, S100A12, NOS2, DKK1, OSM, AR, and OXTR. The area under the curve (AUC) of the model at 1 year was 0.825. Similarly, the AUC values for the validating cohorts were 0.813 and 0.816, respectively. Pathological stage and risk score of the model were independent prognostic factors. This model was effective for both subtypes of EC. CONCLUSIONS We constructed a 7-gene model consisting of HSPA6, S100A12, NOS2, DKK1, OSM, AR, and OXTR. This risk model could be used for prognostic prediction of EC.

11.
Medicine (Baltimore) ; 99(50): e23564, 2020 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-33327312

RESUMO

BACKGROUND: Peripheral neurotoxicity (PN) is a frequent side effect of oxaliplatin treatment, and also is its dose-limiting toxicity. Studies have confirmed that ω-3 polyunsaturated fatty acids (ω-3 PUFAs) had a neuroprotective effect. However, the efficacy of ω-3 PUFAs on the prevention of oxaliplatin-related neurotoxicity remains unclear. We assessed the effect of ω-3 PUFAs on the neurotoxicity in colon cancer patients treated by oxaliplatin combined with capecitabine. METHODS: In a randomized, double-blind, placebo-controlled study, 179 patients with colon cancer receiving oxaliplatin combined with capecitabine were recruited, and randomly assigned to take ω-3 PUFAs, 640 mg t.i.d during chemotherapy and 1 month after the end of the treatment or placebo. All patients were treated with chemotherapy for 6 treatment cycles. The incidence and severity of PN were evaluated, and the nerve conduction was measured before the onset of chemotherapy and 1 month after treatment. In addition, the quality of life was also accessed using Chinese version of European organization for research and treatment of cancer quality of life questionnaire. RESULTS: The incidence of PN in the ω-3 PUFAs group and placebo group was 52.22% and 69.66%, respectively (P = .017). In addition, there was a significant difference in the severity of PN between the 2 groups (P = .017). In terms of motor and sensory nerve conduction, the sensory action potentials amplitude of sural nerve in the ω-3 PUFAs group and placebo group after chemotherapy treatment were (15.01 ±â€Š3.14) and (13.00 ±â€Š3.63) µ V respectively, suggesting there was a significant difference in the 2 groups (P = .000). In addition, the mean score of the global health-status/quality of life was obviously higher in the ω-3 PUFAs group than that in the placebo group. CONCLUSION: ω-3 PUFAs seem to reduce the incidence and severity of oxaliplatin-related neurotoxicity, and improve the quality of patients' life, indicating it is expected to be a potential drug for the treatment of oxaliplatin-related neurotoxicity.


Assuntos
Capecitabina/uso terapêutico , Neoplasias do Colo/tratamento farmacológico , Ácidos Graxos Ômega-3/uso terapêutico , Fármacos Neuroprotetores/uso terapêutico , Síndromes Neurotóxicas/prevenção & controle , Oxaliplatina/toxicidade , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/toxicidade , Capecitabina/administração & dosagem , Método Duplo-Cego , Esquema de Medicação , Ácidos Graxos Ômega-3/administração & dosagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fármacos Neuroprotetores/administração & dosagem , Síndromes Neurotóxicas/etiologia , Oxaliplatina/administração & dosagem , Oxaliplatina/uso terapêutico , Doenças do Sistema Nervoso Periférico/induzido quimicamente , Doenças do Sistema Nervoso Periférico/prevenção & controle , Qualidade de Vida , Inquéritos e Questionários
12.
Inhal Toxicol ; 32(9-10): 388-401, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33043732

RESUMO

OBJECTIVE: The growing applications of nanocelluloses in the fields of advanced nanocomposites, electronics, and medical devices necessitate investigation of their potential adverse effects on human health. The lungs are the primary and the most important route for the entry of nanocelluloses into the human body in occupational settings. However, data on the pulmonary toxicity of cellulose nanofibrils (CNFs) and its molecular mechanism are limited. This study investigated the pulmonary toxicity of CNFs and its genomic expression using the RNA sequencing approach. MATERIALS AND METHODS: Female C57BL/6 mice were administered CNFs at 50 µg/mouse by oropharyngeal aspiration. Samples were collected at 3 and 14 days after exposure to CNFs (DAEC). RESULTS: At three DAEC, the microscopic sections of lungs revealed a significant inflammatory response. In terms of gene expression alterations, 94 genes were up-regulated, and 107 genes were down-regulated. Most of these differentially expressed genes were involved in the inflammatory and immune responses, including chemokines, NK cells, killer cell lectin-like receptors, CD antigens, T cell-specific GTPases, immunity-related GTPase family M members, and interferon-induced proteins encoding genes. However, only 9 and 26 genes at 14 DAEC were significantly up- and down-regulated, respectively. CONCLUSIONS: The pathological analysis of lung sections and the analysis of sequencing data suggested that the homeostasis of mice lungs was restored at 14 DAEC. The findings of this study provide insights into the pulmonary toxicity, and underlying toxicological mechanisms, caused by exposure to CNFs, and are useful for the assessment of the potential toxicity of nanocelluloses.

13.
Front Immunol ; 11: 588079, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33072135

RESUMO

Berberine (BBR) has been reported that it has effects on inhibiting colorectal cancer (CRC). However, the mechanism of BBR on CRC also remains largely unknown. Herein, we investigated the therapeutic effects of BBR on CRC from the perspective of gut microbiota and metabolic alterations, which can provide a holistic view to understand the effects of BBR on CRC. First, azoxymethane (AOM)/dextran sodium sulfate (DSS) mouse was used as CRC animal model, then the degree of colorectal carcinogenesis in AOM/DSS mice with or without BBR administration was measured. The composition and abundance of gut microbiota was investigated by using 16S rRNA. Meanwhile, feces samples were analyzed with 1H NMR spectroscopy to investigate the metabolic alterations. As a result, BBR significantly reduced intestinal tumor development with lower macroscopic polyps and ki-67 expression of intestinal tissue, and better colonic morphology in mice. Moreover, BBR altered the composition of gut microbiota in AOM/DSS mice obviously, which were characterized by a decrease of Actinobacteria and Verrucomicrobia significantly at the phylum level. At the genus level, it was able to suppress pathogenic species, such as f_Erysipelotrichaceae, Alistipes, and elevate some short-chain fatty acids (SCFA)-producing bacteria, including Alloprevotella, Flavonifractor, and Oscillibacter. Metabolic data further revealed that BBR induced metabolic changes in feces focus on regulating glycometabolism, SCFA metabolism and amino acid metabolism, which also provides evidence for alteration of the microbiota because these feces metabolites are the products of interactions between the host and the microbial community. This study showed that BBR induced alterations in microbiota and metabolic in AOM/DSS mice, which might providing new insight into the inhibition effects of BBR on CRC.

14.
Diagn Pathol ; 15(1): 133, 2020 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-33109222

RESUMO

BACKGROUND: Lung cancer (LC) is a malignant tumor originating in the bronchial mucosa or gland of the lung. Circular RNAs (circRNAs) are proved to be key regulators of tumor progression. However, the regulatory effect of circ_0001421 on lung cancer tumorigenesis remains unclear. METHODS: The expression levels of circ_0001421, microRNA-4677-3p (miR-4677-3p) and cell division cycle associated 3 (CDCA3) were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Methyl thiazolyl tetrazolium (MTT), Transwell and Tumor formation assays were performed to explore the role of circ_0001421 in LC. Glucose consumption and lactate production were examined by a Glucose assay kit and a Lactic Acid assay kit. Western blot was utilized to examine the protein levels of Hexokinase 2 (HK2) and CDCA3. The interaction between miR-4677-3p and circ_0001421 or CDCA3 was confirmed by dual-luciferase reporter assay. RESULTS: Circ_0001421 was increased in LC tissues and cells, and knockdown of circ_0001421 repressed cell proliferation, migration, invasion and glycolysis in vitro. Meanwhile, circ_0001421 knockdown inhibited LC tumor growth in vivo. Mechanistically, circ_0001421 could bind to miR-4677-3p, and CDCA3 was a target of miR-4677-3p. Rescue assays manifested that silencing miR-4677-3p or CDCA3 overexpression reversed circ_0001421 knockdown-mediated suppression on cell proliferation, migration, invasion and glycolysis in LC cells. CONCLUSION: Circ_0001421 promoted cell proliferation, migration, invasion and glycolysis in LC by regulating the miR-4677-3p/CDCA3 axis, which providing a new mechanism for LC tumor progression.

15.
BMC Cancer ; 20(1): 904, 2020 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-32962686

RESUMO

BACKGROUND: Colon cancer is a common malignant tumor with a poor prognosis. Abnormal alternative splicing (AS) events played a part in the occurrence and metastasis of the tumor. We aimed to develop a survival-associated AS signature in colon cancer. METHODS: The Percent Spliced In values of AS events were available in The Cancer Genome Atlas (TCGA) SpliceSeq database. Univariate Cox analysis was carried out to detect the prognosis-related AS events. We created a predictive model on account of the survival-associated AS events, which was further validated with a training-testing group design. Kaplan-Meier analysis was applied to assess patient survival. The area under curve (AUC) of receiver operating characteristic (ROC) was performed to evaluate the predictive values of this model. Meanwhile, the clinical relevance of the signature and its regulatory relationship with splicing factors (SFs) were also evaluated. RESULTS: In total, 2132 survival-related AS events were identified from colon cancer samples. We developed an eleven-AS signature, in which the 5-year AUC value was 0.911. Meanwhile, the AUC values at five years were 0.782 and 0.855 in the testing and entire cohort, respectively. Multivariate Cox regression displayed that the T category and the risk score of the signature were independent risk factors of colon cancer survival. Also, we constructed an SFs-AS network based on 11 SFs and 48 AS events. CONCLUSIONS: We identified an eleven-AS signature of colon cancer. This signature could be treated as an independent prognostic factor.

17.
FEMS Microbiol Lett ; 367(17)2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32821904

RESUMO

Phytochromes are a class of photoreceptors found in plants and in some fungi, cyanobacteria, and photoautotrophic and heterotrophic bacteria. Although phytochromes have been structurally characterized in some bacteria, their biological and ecological roles in magnetotactic bacteria remain unexplored. Here, we describe the biochemical characterization of recombinant bacteriophytochrome (BphP) from magnetotactic bacteria Magnetospirillum magneticum AMB-1 (MmBphP). The recombinant MmBphP displays all the characteristic features, including the property of binding to biliverdin (BV), of a genuine phytochrome. Site-directed mutagenesis identified that cysteine-14 is important for chromophore covalent binding and photoreversibility. Arginine-240 and histidine-246 play key roles in binding to BV. The N-terminal photosensory core domain of MmBphP lacking the C-terminus found in other phytochromes is sufficient to exhibit the characteristic red/far-red-light-induced fast photoreversibility of phytochromes. Moreover, our results showed MmBphP is involved in the phototactic response, suggesting its conservative role as a stress protectant. This finding provided us a better understanding of the physiological function of this group of photoreceptors and photoresponse of magnetotactic bacteria.

18.
Appl Microbiol Biotechnol ; 104(18): 7927-7941, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32780289

RESUMO

Light-oxygen-voltage (LOV) proteins are ubiquitous photoreceptors that can interact with other regulatory proteins and then mediate their activities, which results in cellular adaptation and subsequent physiological changes. Upon blue-light irradiation, a conserved cysteine (Cys) residue in LOV covalently binds to flavin to form a flavin-Cys adduct, which triggers a subsequent cascade of signal transduction and reactions. We found a group of natural Cys-less LOV-like proteins in magnetotactic bacteria (MTB) and investigated its physiological functions by conducting research on one of these unusual LOV-like proteins, Amb2291, in Magnetospirillum magneticum. In-frame deletion of amb2291 or site-directive substitution of alanine-399 for Cys mutants impaired the protective responses against hydrogen peroxide, thereby causing stress and growth impairment. Consequently, gene expression and magnetosome formation were affected, which led to high sensitivity to oxidative damage and defective phototactic behaviour. The purified wild-type and A399C-mutated LOV-like proteins had similar LOV blue-light response spectra, but Amb2291A399C exhibited a faster reaction to blue light. We especially showed that LOV-like protein Amb2291 plays a role in magnetosome synthesis and resistance to oxidative stress of AMB-1 when this bacterium was exposed to red light and hydrogen peroxide. This finding expands our knowledge of the physiological function of this widely distributed group of photoreceptors and deepens our understanding of the photoresponse of MTB. KEY POINTS: • We found a group of Cys-less light-oxygen-voltage (LOV) photoreceptors in magnetotactic bacteria, which prompted us to study the light-response and biological roles of these proteins in these non-photosynthetic bacteria. • The Cys-less LOV-like protein participates in the light-regulated signalling pathway and improves resistance to oxidative damage and magnetic crystal biogenesis in Magnetospirillum magneticum. • This result will contribute to our understanding of the structural and functional diversity of the LOV-like photoreceptor and help us understand the complexity of light-regulated model organisms.

19.
Bone ; 141: 115578, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32791331

RESUMO

Angiotensin I converting enzyme (ACE) is a major component of the renin-angiotensin system (RAS). Our previous study demonstrated that activated bone RAS was associated with low peak bone mass induced by prenatal dexamethasone exposure (PDE) in male offspring rats. However, we did not determine whether the inhibition of ACE expression could rescue PDE-induced low peak bone mass. In the present study, we treated pregnant Wistar rats with dexamethasone (0.2 mg/kg.d) on gestational days 9-20 and obtained eight weeks old male offspring rats. Some of the offspring rats from the PDE group were injected lentivirus delivered-ACE siRNA (LV-ACE siRNA) through the intra-bone marrow for 4 weeks. We found that the intra-bone marrow injection of LV-ACE siRNA rescued the impaired peak bone mass accumulation caused by PDE in male offspring rats. Moreover, LV-ACE siRNA ameliorated PDE-induced inhibition of osteogenesis and alleviated PDE-induced RAS activation in the bone tissues in vivo. Our in vitro findings further confirmed that LV-ACE siRNA reversed the suppressed osteogenic differentiation caused by dexamethasone, which can be attributed to alleviated RAS activation. In conclusion, LV-ACE siRNA rescued impaired peak bone mass accumulation caused by PDE through alleviation of local bone RAS activation in male offspring rats.

20.
Nanomaterials (Basel) ; 10(8)2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32751468

RESUMO

Atomic force microscopy (AFM) based nanomanipulation can align the orientation and position of individual carbon nanotubes accurately. However, the flexible deformation during the tip manipulation modifies the original shape of these nanotubes, which could affect its electrical properties and reduce the accuracy of AFM nanomanipulation. Thus, we developed a protocol for searching the synergistic parameter combinations to push single-wall carbon nanotubes (SWCNTs) to maintain their original shape after manipulation as far as possible, without requiring the sample physical properties and the tip-manipulation mechanisms. In the protocol, from a vast search space of manipulating parameters, the differential evolution (DE) algorithm was used to identify the optimal combinations of three parameters rapidly with the DE algorithm and the feedback of the length ratio of SWCNTs before and after manipulation. After optimizing the scale factor F and crossover probability Cr, the values F = 0.4 and Cr = 0.6 were used, and the ratio could reach 0.95 within 5-7 iterations. A parameter region with a higher length ratio was also studied to supply arbitrary pushing parameter combinations for individual manipulation demand. The optimal pushing parameter combination reduces the manipulation trajectory and the tip abrasion, thereby significantly improving the efficiency of tip manipulation for nanowire materials. The protocol for searching the best parameter combinations used in this study can also be extended to manipulate other one-dimensional nanomaterials.

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