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1.
Clin Breast Cancer ; 2020 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-32139270

RESUMO

The androgen receptor (AR) is increasingly considered as a potential biomarker for breast cancer. Nevertheless, the prognostic value of AR expression in patients with triple negative breast cancer (TNBC) remains controversial. Therefore, in this meta-analysis, we investigated AR expression and its impact on survival outcome. PubMed, Embase, the Cochrane Library, and references of articles were searched to identify relevant studies that investigated the association between AR expression and prognosis in patients diagnosed with TNBC and were published between 1946 and May 2019. The hazard ratio (HR) and confidence interval (CI) of disease-free survival, overall survival, distant disease-free survival, and recurrence-free survival were weighted and pooled by using the fixed-effect or random-effect model based on the heterogeneity of included studies. A total of 27 studies including 4914 patients with TNBC were included. AR was expressed in 27.96% (1315/4703) of patients with TNBC. In addition, AR expression in TNBC was not associated with disease-free survival (HR, 0.923; 95% CI, 0.671-1.271; P = .634), overall survival (HR, 0.910; 95% CI, 0.678-1.222; P = .531), distant disease-free survival (HR, 1.02; 95% CI, 0.96-1.08; P = .489), or recurrence-free survival (HR, 0.957; 95% CI, 0.462-1.982; P = .906) in TNBC, regardless of confounding factors and heterogeneity that existed among included studies. In patients with TNBC, AR expression is not associated with prognosis.

2.
Nano Lett ; 2020 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-32163293

RESUMO

Optical anisotropy plays an indispensable role in a variety of optical components. Organic halide perovskites often rely on artificially oriented nanostructures to enhance optical anisotropy due to their in-plane isotropic crystal structure, which results in unnecessary optical losses and fabrication difficulties. Here, we report the large optical anisotropy in two-dimensional perovskite [CH(NH2)2][C(NH2)3]PbI4 crystals. Without specially designing their morphology, we achieved a large photoresponse linear dichroic ratio of 2 and a photoluminescence linear dichroic ratio of 4.7. Furthermore, we identified that the polarization orientation is parallel to the corrugated inorganic layers on every crystal plane by density functional theory calculations. The anisotropy of the ab-plane and ac-plane changes in opposite trend with temperature, suggesting that the perovskite can selectively generate polarized light or unpolarized light from different crystal planes by tuning the temperature. Our studies provide a new platform toward two-dimensional perovskite-based optical polarization devices.

4.
Medicine (Baltimore) ; 99(11): e19434, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32176071

RESUMO

BACKGROUND: We performed a meta-analysis of the efficacy and safety of stem cell therapy as a clinical treatment of knee osteoarthritis. This meta-analysis is expected to provide evidence of the efficacy of stem cell therapy, which is currently controversial, as a conservative treatment for knee osteoarthritis. METHODS: An online search for relevant articles was conducted in the PubMed, EMBASE, and Cochrane Library databases. The search terms were "stem cells" and "osteoarthritis." We conducted a quality assessment of the included articles and extracted the following indicators: Visual Analogue Scale (VAS) score, Subjective International Knee Documentation Committee (IKDC) score, Western Ontario and McMaster Universities (WOMAC) subscales, and adverse events. The RevMan5.3 software was used for determining effect sizes. RESULTS: Nine randomized controlled trials involving 339 patients were included. VAS score and IKDC score from baseline to 24 months were improved in the stem cell therapy group compared to those in the control group. However, no significant difference was observed between the 2 groups in IKDC score changes from baseline to 6 and 12 months, as well as in WOMAC-Pain, WOMAC-Stiffness, and WOMAC-Physical Function score changes at each visit point. CONCLUSION: Stem cell therapy is certainly superior to traditional treatments in the conservative treatment of KOA; it considerably reduces pain with no obvious additional side effects.


Assuntos
Tratamento Conservador , Osteoartrite do Joelho/terapia , Transplante de Células-Tronco , Humanos
5.
BMC Pediatr ; 20(1): 126, 2020 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-32188441

RESUMO

BACKGROUND: Interleukin (IL)-6 plays an essential role in the pathogenesis of systemic juvenile idiopathic arthritis (sJIA). Tocilizumab (TCZ), a kind of biological agent against both membrane and soluble IL-6 receptor, is the only biological agent approved for the treatment of sJIA in China. Infections are the most common adverse events during TCZ therapy, and most of infections are mild or moderate. Severe sepsis originated from gastrointestinal infection is rarely reported. CASE PRESENTATION: In this article, we reported two 13-year-old sJIA patients who suffered from life-threatening infections after TCZ administration. Within one day, both of them presented rapidly progressive conditions that included fever, abdominal pain, dizziness, diarrhea and vomiting, and laboratory tests showed multi-organ dysfunctions. They were diagnosed with severe sepsis and septic shock that were supposed to be caused by the pathogens from the gastrointestinal tract, and they were eventually rescued by timely treatment. In addition, we also reviewed the literature about serious gastrointestinal infections and sepsis in sJIA patients receiving TCZ therapy. CONCLUSIONS: In summary, for sJIA patients with TCZ therapy, invading pathogens from the gastrointestinal tract can cause an intensely systemic infection that may even be fatal. Therefore, it is essential to pay attention to the gastrointestinal management of sJIA patients as well as remind them of their intestinal hygiene.

6.
Plants (Basel) ; 9(4)2020 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-32218186

RESUMO

Non-coding RNAs (ncRNAs) that were once considered "dark matter" or "transcriptional noise" in genomes are research hotspots in the field of epigenetics. The most well-known microRNAs (miRNAs) are a class of short non-coding, small molecular weight RNAs with lengths of 20-24 nucleotides that are highly conserved throughout evolution. Through complementary pairing with the bases of target sites, target gene transcripts are cleaved and degraded, or translation is inhibited, thus regulating the growth and development of organisms. Unlike miRNAs, which have been studied thoroughly, long non-coding RNAs (lncRNAs) are a group of poorly conserved RNA molecules with a sequence length of more than 200 nucleotides and no protein encoding capability; they interact with large molecules, such as DNA, RNA, and proteins, and regulate protein modification, chromatin remodeling, protein functional activity, and RNA metabolism in vivo through cis- or trans-activation at the transcriptional, post-transcriptional, and epigenetic levels. Research on plant lncRNAs is just beginning and has gradually emerged in the field of plant molecular biology. Currently, some studies have revealed that lncRNAs are extensively involved in plant growth and development and stress response processes by mediating the transmission and expression of genetic information. This paper systematically introduces lncRNA and its regulatory mechanisms, reviews the current status and progress of lncRNA research in plants, summarizes the main techniques and strategies of lncRNA research in recent years, and discusses existing problems and prospects, in order to provide ideas for further exploration and verification of the specific evolution of plant lncRNAs and their biological functions.

7.
Artigo em Inglês | MEDLINE | ID: mdl-32222406

RESUMO

OBJECTIVE: Optimal donor sizing for heart transplantation (HT) in adults with congenital heart disease (CHD) remains unclear, given the propensity for pulmonary hypertension related to shunting, staged repairs, and periods of pulmonary overcirculation. We studied HT outcomes related to donor size matching in the adult CHD population. METHODS: We conducted a retrospective cohort analysis of patients with CHD undergoing HT in the United States from January 1, 2000, to December 31, 2015. Patients were selected from the United Network for Organ Sharing database; 827 patients met inclusion criteria and were analyzed. RESULTS: At a median follow-up of 1462 days, 548 (66.3%) subjects were alive and 279 (33.7%) were deceased. All-cause mortality did not differ based on donor sizing (by predicted heart mass ratio: hazard ratio, 1.03; confidence interval, 0.86-1.23; P = .74). Pulmonary hypertension was not significantly associated with survival (by predicted heart mass ratio, χ2 = 2.01, P = .73). CONCLUSIONS: Our data demonstrate that donor oversizing, to the extent used in current practice, does not affect survival after HT in adults with CHD. Our findings from the United Network for Organ Sharing database demonstrate that donor oversizing in these patients is not associated with improved mortality.

8.
Toxicol Appl Pharmacol ; 394: 114950, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-32147540

RESUMO

The hypothalamic paraventricular nucleus (PVN) plays crucial roles in central cardiovascular regulation. Increasing evidence in humans and rodents shows that vitamin D intake is important for achieving optimal cardiovascular function. The purpose of this study was to investigate whether calcitriol, an active form of vitamin D, improves autonomic and cardiovascular function in hypertensive rats and whether PVN oxidative stress and inflammation are involved in these beneficial effects. Male spontaneously hypertensive rats (SHR) and normotensive control Wistar Kyoto (WKY) rats were treated with either calcitriol (40 ng/day) or vehicle (0.11 µL/h) through chronic PVN infusion for 4 weeks. Blood pressure and heart rate were recorded continuously by radiotelemetry. PVN tissue, heart and plasma were collected for molecular and histological analysis. Compared to WKY rats, SHR exhibited increased systolic blood pressure, sympathetic drive, and cardiac hypertrophy and remodeling. These were associated with higher mRNA and protein expression levels of high mobility box 1 (HMGB1), receptor for advanced glycation end products (RAGE), toll-like receptor 4 (TLR4), nuclear factor-kappa B (NF-κB), proinflammatory cytokines, NADPH oxidase subunit in the PVN. In addition, increased norepinephrine in plasma, elevated reactive oxygen species levels and activation of microglia in the PVN were also observed in SHR. Chronic calcitriol treatment ameliorated these changes but not in WKY rats. Our results demonstrate that chronic infusion of calcitriol in the PVN ameliorates hypertensive responses, sympathoexcitation and retains cardiovascular function in SHR. Reduced inflammation and oxidative stress within the PVN are involved in these calcitriol-induced effects.

9.
Medicine (Baltimore) ; 99(11): e19388, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32176063

RESUMO

BACKGROUND: This meta-analysis focuses on the controversial efficacy and safety of platelet-rich plasma (PRP) as compared with hyaluronic acid (HA) in the clinical treatment of knee osteoarthritis. We have attempted to provide an evidence-based medicine protocol for the conservative treatment of knee osteoarthritis. In addition, we included the latest relevant literature in this meta-analysis, and a staging study was conducted to compare the therapeutic effects of PRP and HA for knee osteoarthritis over different time periods. METHODS: An online computer search with "platelet-rich plasma" and "knee osteoarthritis" as search terms was conducted in the PubMed, EMBASE, and Cochrane Library databases. We conducted a quality assessment of the retrieved literature and extracted the following indicators: visual analog scale (VAS) score, subjective International Knee Documentation Committee (IKDC) score, Western Ontario and McMaster Universities (WOMAC) score, Knee Injury and Osteoarthritis Outcome Score (KOOS), and adverse events. RevMan5.3 software was used to determine the effect sizes, and indicators were compared across studies at three different time points from the administration of treatment. RESULTS: A total of 14 randomized controlled trials (RCTs) involving 1350 patients were included. Long-term VAS, IKDC, WOMAC-Pain, WOMAC-Stiffness, WOMAC-Physical Function, and WOMAC-Total scores at each time point were higher in the PRP group than in the HA group. There were no significant differences in the remaining indicators between the two groups. CONCLUSION: Compared with HA, PRP offers obvious advantages in the conservative treatment of knee osteoarthritis. Treatment with PRP can reduce long-term pain and improve knee joint function with no additional risks. Therefore, PRP can be widely used for the conservative treatment of knee osteoarthritis.


Assuntos
Tratamento Conservador/métodos , Ácido Hialurônico/uso terapêutico , Osteoartrite do Joelho/diagnóstico , Osteoartrite do Joelho/terapia , Plasma Rico em Plaquetas , Amplitude de Movimento Articular/efeitos dos fármacos , Feminino , Humanos , Injeções Intra-Articulares , Masculino , Medição da Dor , Prognóstico , Amplitude de Movimento Articular/fisiologia , Medição de Risco , Índice de Gravidade de Doença , Resultado do Tratamento , Viscossuplementos/uso terapêutico
10.
Dalton Trans ; 2020 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-32211724

RESUMO

Central-radial bi-porous nanocatalysts were synthesized by derivation from dendritic porous supports with hierarchical inorganic functional layers. The nanostructure exhibited a high unit loading capacity, accessible internal catalytic sites and protective mesoporous shell encapsulation. The nanocatalysts were utilized for efficient and stable heterogeneous catalytic reduction of 4-nitrophenol to 4-aminophenol with robust magnetic recyclability.

11.
Plant Physiol Biochem ; 149: 27-35, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32035250

RESUMO

Ornamental crabapple is an important woody ornamental plant with flower colors ranging from white to pink to red, and the degree of redness is directly related to the anthocyanin content. To explore the molecular mechanism leading to the variation in flower color in ornamental crabapple, transcriptome sequencing using the Illumina and PacBio Sequel platforms revealed the difference in gene expression between the petals of plants with white and red flowers in the half-sib family. In total, the analysis identified 603 differentially expressed genes (DEGs), including 449 upregulated and 154 downregulated genes. GO and KEGG enrichment analyses of the DEGs showed that the oxidation-reduction process and catalytic activity were more active in red petals, and most of the DEGs were involved in secondary metabolite synthesis and plant hormone signaling. Among the 603 DEGs, 10 were enriched as structural genes. Transcription factors related to anthocyanin synthesis and five genes related to anthocyanin transport and degradation were highly expressed in red petals. In addition, this study found that five AUX gene signals were differentially expressed in the two petal types. The discovery of these DEGs indicates that plant endogenous hormones also exert a regulatory effect on flower color.

12.
Zhongguo Shi Yan Xue Ye Xue Za Zhi ; 28(1): 235-241, 2020 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-32027283

RESUMO

OBJECTIVE: To establish a novel flow cytometric immunobead array (FCIA) for detecting plasma von Willebrand factor antigen (vWF:Ag), and to analyze the clinical value of FCIA in predicting the prognosis of patients with ischemic stroke (IS). METHODS: Anti-human vWF monoclonal antibody SZ29 IgG was coated on microspheres overnight, the diluted plasma was added after blocking, then incubated with FITC-conjugated sheep-anti-human vWF IgG polyclonal antibody, and finally detected by flow cytometry. The plasma vWF in 21 case of von Willebrand disease (vWD) and 105 controls (CTL) were detected by FCIA and ELISA, so as to carry out methodological assessment. Plasma vWF:Ag of 61 IS patients was detected by FCIA and the data of prognosis followed-up for 2-year were collected. RESULTS: The linear fitting of FCIA was good (R2=0.99) without significant difference between FCIA and ELISA. The Bland-Altman bias was 1.12% with 95% limits of agreement that spanned from -45.06% to 47.30%, and the slope of the linear regression was 0.97 (r=0.86, P<0.01). Importantly, the FCIA method was faster than ELISA, and superior to the ELISA in the detection of low levels of vWF:Ag. The levels of vWF:Ag, vWF:GPIbR and vWF:CB in IS patients were significantly higher than those in healthy controls (Z=8.36, 8.71, 6.22, respectively, P<0.01). CONCLUSION: The FCIA for detecting plasma vWF:Ag is not only an effective supplement to ELISA, but also the efficiency is faster and more sensitive, thus improves the diagnosis of type 3 vWD. Elevated levels of vWF: Ag in IS patients indicate the poor recovery of daily activities and prognosis.


Assuntos
Doenças de von Willebrand , Animais , Anticorpos , Citometria de Fluxo , Humanos , Ovinos , Acidente Vascular Cerebral , Fator de von Willebrand
13.
Environ Microbiol Rep ; 12(2): 229-240, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32052588

RESUMO

Arbuscular mycorrhizal fungi (AMF) play an important role in maintaining plant diversity and productivity in grassland ecosystems. However, very few studies have investigated how AMF and plant communities co-vary between contrasting environments in natural ecosystems. Intensive sampling (50 soil samples) was conducted in natural open grasslands at both 3570 and 4556 m on Mount Segrila on the Southeast Tibetan Plateau. We used 454-pyrosequencing to investigate soil AMF communities and to explore relationships between AMF diversity and plant richness, productivity and community composition. AMF diversity was negatively correlated with plant richness at 3570 m but positively at 4556 m. Differences in AMF community composition between elevations were attributable to plant community composition, soil pH and available phosphorus concentration. The AMF community was more phylogenetically clustered at the higher elevation than the lower elevation. However, greater phylogenetic clustering (under dispersion) of AMF communities at the two elevations was positively correlated with above-ground biomass. Our results indicate that plant community composition and environmental filtering are the primary drivers structuring the AMF community. Phylogenetic relatedness may be important in explaining the function of AMF communities in alpine ecosystems.

14.
Am J Pathol ; 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-32035060

RESUMO

Liver regeneration is a fundamental biological process required for sustaining body homeostasis and restoring liver function after injury. Emerging evidence demonstrates that cytokines, growth factors, and multiple signaling pathways contribute to liver regeneration. Mammalian target of rapamycin complex 2 (mTORC2) regulates cell metabolism, proliferation and survival. The major substrates for mTORC2 are the AGC family members of kinases, including AKT, SGK, and PKC-α. We investigated the functional roles of mTORC2 during liver regeneration. Partial hepatectomy (PHx) was performed in liver-specific Rictor (the pivotal unit of mTORC2 complex) knockout (RictorLKO) and wild-type (Rictorfl/fl) mice. Rictor-deficient mice were found to be more intolerant to PHx and displayed higher mortality after PHx. Mechanistically, loss of Rictor resulted in decreased Akt phosphorylation, leading to a delay in hepatocyte proliferation and lipid droplets formation along liver regeneration. Overall, these results indicate an essential role of the mTORC2 signaling pathway during liver regeneration.

15.
Medicine (Baltimore) ; 99(7): e19066, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32049807

RESUMO

Previous work suggests that the long noncoding RNA HCC associated long non-coding RNA (HANR) is associated with hepatocellular carcinoma (HCC) progression, but its significance in the context of colorectal cancer (CRC) remains to be determined. Therefore, in this study we assessed the prognostic and diagnostic value of HANR in patients suffering from CRC.The HANR expression in 165 pairs of CRC cancer and adjacent non-cancerous prostate tissues was measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis. Student t test was conducted for intergroup comparison. Pearson correlation test was used for correlation analysis. Survival curves were carried out by the Kaplan-Meier method and evaluated using the log-rank test. Multivariable Cox proportional hazard risk regression model was performed to screen the independent factor affected the prognosis of CRC patients.In this study, levels of HANR were significantly higher in CRC tumor samples relative to adjacent normal tissue samples (P < .001). A ROC analysis suggested HANR expression could be reliably used to differentiate between normal and CRC tumor tissue. In addition, elevated HANR expression was positively correlated with more advanced and aggressive CRC features, such as a larger tumor size (P = .003), increased invasion depth (P = .012), and more advanced TNM stage (P = .011). Survival analyses revealed that elevated HANR expression was correlated with worse overall survival (P = .002) and disease-free survival (P = .003). A multivariate analysis further confirmed the relevance of HANR as an independent predictor of CRC patient outcomes.In summary, these results indicate that the lncRNA HANR is a promising prognostic indicator in CRC patients.


Assuntos
Biomarcadores Tumorais/genética , Neoplasias Colorretais/diagnóstico , RNA Longo não Codificante/genética , Regulação para Cima , Adulto , Idoso , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Detecção Precoce de Câncer , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Estadiamento de Neoplasias , Prognóstico , Análise de Sobrevida
16.
JACC Heart Fail ; 8(2): 122-130, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32000962

RESUMO

OBJECTIVES: The purpose of this study was to examine race- and sex-based variation in the associations between modifiable risk factors and incident heart failure (HF) among the SCCS (Southern Community Cohort Study) participants. BACKGROUND: Low-income individuals in the southeastern United States have high HF incidence rates, but relative contributions of risk factors to HF are understudied in this population. METHODS: We studied 27,078 black or white SCCS participants (mean age: 56 years, 69% black, 63% women) enrolled between 2002 and 2009, without prevalent HF, receiving Centers for Medicare and Medicaid Services. The presence of hypertension, diabetes mellitus, physical underactivity, high body mass index, smoking, high cholesterol, and poor diet was assessed at enrollment. Incident HF was ascertained using International Classification of Diseases-9th revision, codes 428.x in Centers for Medicare and Medicaid Services data through December 31, 2010. Individual risk and population attributable risk for HF for each risk factor were quantified using multivariable Cox models. RESULTS: During a median (25th, 75th percentile) 5.2 (3.1, 6.7) years, 4,341 (16%) participants developed HF. Hypertension and diabetes were associated with greatest HF risk, whereas hypertension contributed the greatest population attributable risk, 31.8% (95% confidence interval: 27.3 to 36.0). In black participants, only hypertension and diabetes associated with HF risk; in white participants, smoking and high body mass index also associated with HF risk. Physical underactivity was a risk factor only in white women. CONCLUSIONS: In this high-risk, low-income cohort, contributions of risk factors to HF varied, particularly by race. To reduce the population burden of HF, interventions tailored for specific race and sex groups may be warranted.

17.
BMC Immunol ; 21(1): 6, 2020 02 17.
Artigo em Inglês | MEDLINE | ID: mdl-32066371

RESUMO

BACKGROUND: There is a growing body of evidences indicating iNOS has involved in the pathogenesis of SLE. However, the role of iNOS in SLE is inconsistency. This systematic review was designed to evaluate the association between iNOS and SLE. RESULTS: Six studies were included, reporting on a total of 277 patients with SLE. The meta-analysis showed that SLE patients had higher expression of iNOS at mRNA level than control subjects (SMD = 2.671, 95%CI = 0.446-4.897, z = 2.35, p = 0.019), and a similar trend was noted at the protein level (SMD = 3.602, 95%CI = 1.144-6.059, z = 2.87, p = 0.004) and positive rate of iNOS (OR = 9.515, 95%CI = 1.915-47.281, z = 2.76, p = 0.006) were significantly higher in SLE group compared with control group. No significant difference was observed on serum nitrite level between SLE patients and control subjects (SMD = 2.203, 95%CI = -0.386-4.793, z = 1.64, p = 0.095). The results did not modify from different sensitivity analysis, representing the robustness of this study. No significant publication bias was detected from Egger's test. CONCLUSIONS: There was a positive correlation between increasing iNOS and SLE. However, the source of iNOS is unknown. Besides NO pathway, other pathways also should be considered. More prospective random studies are needed in order to certify our results.

18.
Genomics ; 112(3): 2459-2466, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32014522

RESUMO

The chloroplast genome (CPG) is a powerful tool for phylogenetic studies. Many CPGs have been determined using NGS. However, the large nuclear-genome and difficult CPG-DNA separation in conifers limit their application in related research. In this study, three methods (PCR + Sanger, PCR + HiSeq, cpDNA+HiSeq) for obtaining the CPGs of Pinus massoniana were compared for sequence accuracy, time and cost. PCR + Sanger obtained the most accurate CPGs with advantages in cost (3.08$/kb) and time (2-3 days); PCR + HiSeq generated some DNA fragments with low depth, and the SNPs false-positive-rate (0.44) and sequencing error-rate (0.0265) of this method were higher than those of the cpDNA+HiSeq. Moreover, the cost (~6.17$/kb) and time (4-5 weeks) would significantly increase when HiSeq sequencing were outsourced to sequencing service company. Thus, for the study of intraspecific and interspecies variation in CPGs, CPG sequences can be obtained by comprehensive methods to bridge the method shortcomings. Scuh as sequence accuracy, cost and time.

19.
ACS Appl Mater Interfaces ; 12(11): 12436-12444, 2020 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-32096397

RESUMO

The fabrication of multifunctional materials that interface with living environments is a problem of great interest. A variety of structural design concepts have been integrated with functional materials to form biodevices and surfaces for health monitoring. In particular, approaches based on kirigami-inspired cuts can engineer flexibility in materials through the creation of patterned defects. Here, the fabrication of a biodegradable and biofunctional "silk kirigami" material is demonstrated. Mechanically flexible, free-standing, optically transparent, large-area biomaterial sheets with precisely defined and computationally designed microscale cuts can be formed using a single-step photolithographic process. Using modeling techniques, it is shown how cuts can generate remarkable "self-shielding" leading to engineered elastic behavior and deformation. As composites with conducting polymers, flexible, intrinsically electroactive sheets can be formed. Importantly, the silk kirigami sheets are biocompatible, can serve as substrates for cell culture, and be proteolytically resorbed. The unique properties of silk kirigami suggest a host of applications as transient, "green", functional biointerfaces, and flexible bioelectronics.

20.
Ecology ; : e03011, 2020 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-32065669

RESUMO

The maximum entropy theory of ecology (METE) applies the concept of "entropy" from information theory to predict macroecological patterns. The energetic predictions of the METE rely on predetermined metabolic scaling from external theories, and this reliance diminishes the testability of the theory. In this work, I build parametrized METE models by treating the metabolic scaling exponent as a free parameter, and I use the maximum likelihood method to obtain empirically plausible estimates of the exponent. I test the models using the individual tree data from an oak-dominated deciduous forest in the northeastern USA and from a tropical forest in central Panama. My analysis show that the metabolic scaling exponents predicted from the parametrized METE models deviate from that of the metabolic theory of ecology and exhibit large variation, at both community and population levels. Assemblage and population abundance may act as ecological constraints that regulate the individual-level metabolic scaling behavior. This study provides a novel example of the use of the parametrized METE models to reveal the biological processes of individual organisms. The implication and possible extensions of the parametrized METE models are discussed.

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