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1.
Sci Data ; 11(1): 388, 2024 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-38627435

RESUMO

Construction waste is unavoidable in the process of urban development, causing serious environmental pollution. Accurate assessment of municipal construction waste generation requires building construction waste identification models using deep learning technology. However, this process requires high-quality public datasets for model training and validation. This study utilizes Google Earth and GF-2 images as the data source to construct a specific dataset of construction waste landfills in the Changping and Daxing districts of Beijing, China. This dataset contains 3,653 samples of the original image areas and provides mask-labeled images in the semantic segmentation domains. Each pixel within a construction waste landfill is classified into 4 categories of the image areas, including background area, vacant landfillable area, engineering facility area, and waste dumping area. The dataset contains 237,115,531 pixels of construction waste and 49,724,513 pixels of engineering facilities. The pixel-level semantic segmentation labels are provided to quantify the construction waste yield, which can serve as the basic data for construction waste extraction and yield estimation both for academic and industrial research.

2.
ACS Omega ; 9(13): 14692-14703, 2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38585085

RESUMO

In recent years, CO2 flooding has become one of the main enhanced oil recovery (EOR) methods, especially for tight formations in different oilfields around the world. Most of the CO2 flooding projects carried out in the world are based on miscible flooding, however, this technique is less effective in China because of the depth of the reservoirs and the heavy components of the crude oil. Near-miscible flooding and immiscible flooding have also been gradually applied to China's domestic oil fields, and have achieved certain oil increase effects, but there are still some challenges such as gas channeling, corrosion, and solid phase deposition in the process of CO2 flooding. In this paper, through a detailed review of recent domestic and foreign cases of enhanced oil recovery, the effects of development methods of low permeability and ultralow permeability reservoirs under different miscible degrees are analyzed, and the solutions to some of the existing problems in field tests and experience are systematically summarized. According to the results of field tests, both miscible flooding and near-miscible flooding have similar effects and can achieve better recovery increment, with a long effect period and slow gas breakthrough speed. In addition, the problems of gas channeling, corrosion, and solid phase deposition occurring in the process of CO2 flooding are analyzed, and solutions such as a change in injection methods and coatings are put forward, which effectively promote the development of CO2 flooding technology. Those suggestions are of great significance for improving the oil recovery rate of unconventional oil reservoirs, ensuring the national energy supply, and low-carbon emissions reduction in China.

3.
Front Psychiatry ; 15: 1354922, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38495911

RESUMO

Objective: This study was designed to investigate the prevalence of religious belief and its relationship with psychiatric symptoms among Chinese adolescents. Methods: This study recruited 11,603 adolescents in Grades 7-9 from March 21 to 31, 2020 in five cities in China. The religious beliefs of adolescents were collected by asking whether they held religious beliefs and what type of religious beliefs they held. The Patient Health Questionnaire-9 (PHQ-9) and the Generalized Anxiety Disorder-7 Scale (GAD-7) were used to assess depressive and anxiety symptoms in all adolescents. Demographics, religious beliefs, and mental health status were collected through the professional version of Wenjuanxing. Results: Of 11,069 valid questionnaires collected, 847 (7.7%) reported holding religious beliefs. Adolescents with religious beliefs showed significantly more severe symptoms of depression and anxiety compared to those without religious beliefs (both p<0.05). Logistic regression analysis revealed that religious belief was a risk factor for symptoms of depression (OR = 1.37, 95%CI: 1.16-1.61, p < 0.001) and anxiety (OR = 1.49, 95%CI: 1.23-1.79, p < 0.001) after controlling age, gender, and parental marital status. Conclusions: Our findings suggest that religiousness in adolescents was associated with a higher likelihood of depression/more intense depressive symptoms. In addition, religious Chinese adolescents should be provided with more resources to help them cope with mental health concerns.

4.
Materials (Basel) ; 17(5)2024 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-38473458

RESUMO

This Special Issue provides readers with up-to-date information on the recent progress in the structure transition, processing, characterization, and applications of metals, including ferrous and nonferrous metals [...].

5.
J Biol Chem ; 300(3): 105772, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38382674

RESUMO

Pre-mRNA splicing is a precise regulated process and is crucial for system development and homeostasis maintenance. Mutations in spliceosomal components have been found in various hematopoietic malignancies (HMs) and have been considered as oncogenic derivers of HMs. However, the role of spliceosomal components in normal and malignant hematopoiesis remains largely unknown. Pre-mRNA processing factor 31 (PRPF31) is a constitutive spliceosomal component, which mutations are associated with autosomal dominant retinitis pigmentosa. PRPF31 was found to be mutated in several HMs, but the function of PRPF31 in normal hematopoiesis has not been explored. In our previous study, we generated a prpf31 knockout (KO) zebrafish line and reported that Prpf31 regulates the survival and differentiation of retinal progenitor cells by modulating the alternative splicing of genes involved in mitosis and DNA repair. In this study, by using the prpf31 KO zebrafish line, we discovered that prpf31 KO zebrafish exhibited severe defects in hematopoietic stem and progenitor cell (HSPC) expansion and its sequentially differentiated lineages. Immunofluorescence results showed that Prpf31-deficient HSPCs underwent malformed mitosis and M phase arrest during HSPC expansion. Transcriptome analysis and experimental validations revealed that Prpf31 deficiency extensively perturbed the alternative splicing of mitosis-related genes. Collectively, our findings elucidate a previously undescribed role for Prpf31 in HSPC expansion, through regulating the alternative splicing of mitosis-related genes.


Assuntos
Fatores de Processamento de RNA , Proteínas de Peixe-Zebra , Peixe-Zebra , Animais , Desenvolvimento Embrionário , Mutação , Precursores de RNA/metabolismo , Fatores de Processamento de RNA/metabolismo , Células-Tronco/metabolismo , Peixe-Zebra/genética , Peixe-Zebra/crescimento & desenvolvimento , Peixe-Zebra/metabolismo , Proteínas de Peixe-Zebra/metabolismo
6.
Commun Chem ; 6(1): 176, 2023 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-37612464

RESUMO

Bicyclic boronates play critical roles in the discovery of functional materials and antibacterial agents, especially against deadly bacterial pathogens. Their practical and convenient preparation is in high demand but with great challenge. Herein, we report an efficient strategy for the preparation of bicyclic boronates through metal-free heteroatom-directed alkenyl sp2-C‒H borylation. This synthetic approach exhibits good functional group compatibility, and the corresponding boronates bearing halides, aryls, acyclic and cyclic frameworks are obtained with high yields (43 examples, up to 95% yield). Furthermore, a gram-scale experiment is conducted, and downstream transformations of the bicyclic boronates are pursued to afford natural products, drug scaffolds, and chiral hemiboronic acid catalysts.

7.
Front Cell Dev Biol ; 11: 1169941, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37351277

RESUMO

Introduction: Pathogenic mutations in RPGR ORF15, one of two major human RPGR isoforms, were responsible for most X-linked retinitis pigmentosa cases. Previous studies have shown that RPGR plays a critical role in ciliary protein transport. However, the precise mechanisms of disease triggered by RPGR ORF15 mutations have yet to be clearly defined. There are two homologous genes in zebrafish, rpgra and rpgrb. Zebrafish rpgra has a single transcript homologous to human RPGR ORF15; rpgrb has two major transcripts: rpgrb ex1-17 and rpgrb ORF15, similar to human RPGR ex1-19 and RPGR ORF15, respectively. rpgrb knockdown in zebrafish resulted in both abnormal development and increased cell death in the dysplastic retina. However, the impact of knocking down rpgra in zebrafish remains undetermined. Here, we constructed a rpgra mutant zebrafish model to investigate the retina defect and related molecular mechanism. Methods: we utilized transcription activator-like effector nuclease (TALEN) to generate a rpgra mutant zebrafish. Western blot was used to determine protein expression. RT-PCR was used to quantify gene transcription levels. The visual function of embryonic zebrafish was detected by electroretinography. Immunohistochemistry was used to observe the pathological changes in the retina of mutant zebrafish and transmission electron microscope was employed to view subcellular structure of photoreceptor cells. Results: A homozygous rpgra mutant zebrafish with c.1675_1678delins21 mutation was successfully constructed. Despite the normal morphological development of the retina at 5 days post-fertilization, visual dysfunction was observed in the mutant zebrafish. Further histological and immunofluorescence assays indicated that rpgra mutant zebrafish retina photoreceptors progressively began to degenerate at 3-6 months. Additionally, the mislocalization of cone outer segment proteins (Opn1lw and Gnb3) and the accumulation of vacuole-like structures around the connecting cilium below the OSs were observed in mutant zebrafish. Furthermore, Rab8a, a key regulator of opsin-carrier vesicle trafficking, exhibited decreased expression and evident mislocalization in mutant zebrafish. Discussion: This study generated a novel rpgra mutant zebrafish model, which showed retinal degeneration. our data suggested Rpgra is necessary for the ciliary transport of cone-associated proteins, and further investigation is required to determine its function in rods. The rpgra mutant zebrafish constructed in this study may help us gain a better understanding of the molecular mechanism of retinal degeneration caused by RPGR ORF15 mutation and find some useful treatment in the future.

8.
Sci Adv ; 9(19): eadg1237, 2023 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-37163601

RESUMO

In nature, cyclopropylcarbinyl cation is often involved in cationic cascade reactions catalyzed by natural enzymes to produce a great number of structurally diverse natural substances. However, mimicking this natural process with artificial organic catalysts remains a daunting challenge in synthetic chemistry. We report a small molecule-catalyzed asymmetric rearrangement of cyclopropylcarbinyl cations, leading to a series of chiral homoallylic sulfide products with good to excellent yields and enantioselectivities (up to 99% enantiomeric excess). In the presence of a chiral SPINOL-derived N-triflyl phosphoramide catalyst, the dehydration of prochiral cyclopropylcarbinols occurs rapidly to generate symmetrical cyclopropylcarbinyl cations, which are subsequently trapped by thione-containing nucleophiles. A subgram-scale experiment and multiple downstream transformations of the sulfide products are further pursued to demonstrate the synthetic utility. Notably, a few heteroaromatic sulfone derivatives could serve as "covalent warhead" in the enzymatic inhibition of severe acute respiratory syndrome coronavirus 2 main protease.

9.
J Biomater Sci Polym Ed ; 34(2): 258-275, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-35984741

RESUMO

Prevention of encrustation on the surface has always been the biggest challenge for urological implants. In the field of ureteral stent design, biodegradability has attracted much attention in recent years, because biodegradable ureteral stents not only avoid secondary intervention, but also prevent encrustation due to surface renewal by degradation process. Furthermore, researches have focus on some surface parameters to provide guidance for the development of stent materials, such as hydrophilicity or surface charge. In this work, we synthesized two types of poly(ester-carbonate)s, poly(L-lactide-co-5-amino-1,3-dioxan-2-one) (P(LA-co-AC)) containing amino, and poly (L-lactide-co-5-methyl-5-carboxyl-1,3-dioxan-2-one) (P(LA-co-MCC)) containing carboxyl. Blending P(LA-co-AC) and P(LA-co-MCC) with poly(L-lactide-co-Ɛ-caprolactone) (PLACL) respectively, two types of ureteral stent materials were prepared. Due to the influence of ions formed by the dissociation of amino and carboxyl, two types of materials show differences in surface charge analyses. We further developed a dynamic urinary extracorporeal circulation (DUEC) system to assess in vitro encrustation of materials with different surface charges. The results of this comparative study identified that the materials with strong negative surface charge were most favorable for use as ureteral stent, and provided a new approach to surmount the problems faced by urological surgery which complied with the future trend of biodegradable ureteral stent design.


Assuntos
Ureter , Stents
10.
Front Psychol ; 13: 1007190, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36389527

RESUMO

Many scholars have focused on understanding ways of how to suppress knowledge hiding by employees. Existing studies have demonstrated that mindfulness could effectively inhibit employees' knowledge hiding. This study aims to investigate the impact of leader-subordinate mindfulness congruence on subordinate knowledge hiding and its internal mechanisms. Based on the role theory, we collected 169 leadership data and 368 employee data at three time-points through collecting questionnaire of matching leaders and subordinates. In addition, we used polynomial regression and response surface analysis to validate our research hypotheses. The results demonstrated that: (i) Compared with the "high leader-high subordinate" mindfulness congruence condition, subordinates in the "low leader-low subordinate" mindfulness congruence condition were more likely to exhibit knowledge hiding. (ii) Compared with the "low leader-high subordinate" mindfulness incongruence, subordinates under the "high leader-low subordinate" mindfulness incongruence are more likely to exhibit knowledge hiding. (iii) The more incongruent the mindfulness between the leader and the subordinate is, the more likely an employee is to exhibit knowledge hiding. (iv) Emotional exhaustion mediated the correlation between leader-subordinate mindfulness congruence and knowledge hiding. (v) When the gender of the leader and the subordinate is different, the impact of mindfulness congruence on the inhibition of emotional exhaustion is stronger. This study provides a new perspective for researching the impact of mindfulness on individual behavior and provides a new idea for the research related to inhibiting knowledge hiding.

11.
Entropy (Basel) ; 24(8)2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-36010788

RESUMO

Accurate and fine-grained prediction of PM2.5 concentration is of great significance for air quality control and human physical and mental health. Traditional approaches, such as time series, recurrent neural networks (RNNs) or graph convolutional networks (GCNs), cannot effectively integrate spatial-temporal and meteorological factors and manage dynamic edge relationships among scattered monitoring stations. In this paper, a spatial-temporal causal convolution network framework, ST-CCN-PM2.5, is proposed. Both the spatial effects of multi-source air pollutants and meteorological factors are considered via spatial attention mechanism. Time-dependent features in causal convolution networks are extracted by stacked dilated convolution and time attention. All the hyper-parameters in ST-CCN-PM2.5 are tuned by Bayesian optimization. Haikou air monitoring station data are employed with a series of baselines (AR, MA, ARMA, ANN, SVR, GRU, LSTM and ST-GCN). Final results include the following points: (1) For a single station, the RMSE, MAE and R2 values of ST-CCN-PM2.5 decreased by 27.05%, 10.38% and 3.56% on average, respectively. (2) For all stations, ST-CCN-PM2.5 achieve the best performance in win-tie-loss experiments. The numbers of winning stations are 68, 63, and 64 out of 95 stations in RMSE (MSE), MAE, and R2, respectively. In addition, the mean MSE, RMSE and MAE of ST-CCN-PM2.5 are 4.94, 2.17 and 1.31, respectively, and the R2 value is 0.92. (3) Shapley analysis shows wind speed is the most influencing factor in fine-grained PM2.5 concentration prediction. The effects of CO and temperature on PM2.5 prediction are moderately significant. Friedman test under different resampling further confirms the advantage of ST-CCN-PM2.5. The ST-CCN-PM2.5 provides a promising direction for fine-grained PM2.5 prediction.

12.
Nat Commun ; 12(1): 7228, 2021 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-34893631

RESUMO

Thermal metamaterials have exhibited great potential on manipulating, controlling and processing the flow of heat, and enabled many promising thermal metadevices, including thermal concentrator, rotator, cloak, etc. However, three long-standing challenges remain formidable, i.e., transformation optics-induced anisotropic material parameters, the limited shape adaptability of experimental thermal metadevices, and a priori knowledge of background temperatures and thermal functionalities. Here, we present robustly printable freeform thermal metamaterials to address these long-standing difficulties. This recipe, taking the local thermal conductivity tensors as the input, resorts to topology optimization for the freeform designs of topological functional cells (TFCs), and then directly assembles and prints them. Three freeform thermal metadevices (concentrator, rotator, and cloak) are specifically designed and 3D-printed, and their omnidirectional concentrating, rotating, and cloaking functionalities are demonstrated both numerically and experimentally. Our study paves a powerful and flexible design paradigm toward advanced thermal metamaterials with complex shapes, omnidirectional functionality, background temperature independence, and fast-prototyping capability.

13.
Chem Commun (Camb) ; 57(76): 9724-9727, 2021 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-34474456

RESUMO

A diastereo- and enantioselective rhodium(III)-catalyzed reductive cyclization of cyclohexadienone-tethered terminal alkenes and (E)-1,2-disubstituted alkenes (1,6-dienes) is reported, providing cis-bicyclic products bearing three contiguous stereocenters with good yields and high diastereo- and enantioselectivities. The kinetic resolution of the racemic precursor is also achieved with good efficiency. Moreover, a subgram-scale experiment, several transformations of the cyclization product, and one-pot preparation of bridged polycyclic frameworks are presented.

14.
Psychosom Med ; 83(9): 1082-1088, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34419998

RESUMO

OBJECTIVE: Comorbid depression is common in schizophrenia, and sex differences are prominent in many aspects of schizophrenia. However, few studies have investigated sex difference in comorbid depression in schizophrenia. This large sample study aimed to investigate sex differences in first-episode drug-naive (FEDN) patients with schizophrenia comorbid major depressive episode (SZ-MDE). METHODS: A total of 996 FEDN patients with schizophrenia (472 males/524 females) were recruited. The 17-item Hamilton Depression Rating Scale and Positive and Negative Syndrome Scale (PANSS) were applied. RESULTS: There was no difference in the prevalence of comorbid MDE between male and female patients with schizophrenia. Among SZ-MDE patients, men had more severe psychotic symptoms (scores of PANSS total scale, negative scale, and general psychopathology scale), more severe depressive symptoms, and higher proportion of severe depression than women (all p < .001). The early onset age of schizophrenia, smoking, and PANSS positive score were the risk factors for comorbid MDE only in female patients with schizophrenia (all p < .05). Furthermore, in female patients with SZ-MDE, smoking was associated with the severity category of depression (p = .001, odds ratio = 2.70). Multiple variable regression demonstrated that the Hamilton Depression Rating Scale score correlated with PANSS general psychopathology (p = .01) and total scores (p = .04) in female SZ-MDE. CONCLUSIONS: Our results indicate sex differences in proportion of severe depression, clinical symptoms, and factors of comorbid MDE in FEDN patients with schizophrenia. These sex differences have clinical implications for the treatment of depression as related to the nature and severity of psychopathological symptoms in patients with schizophrenia.


Assuntos
Transtorno Depressivo Maior , Preparações Farmacêuticas , Esquizofrenia , Depressão/epidemiologia , Transtorno Depressivo Maior/complicações , Transtorno Depressivo Maior/epidemiologia , Feminino , Humanos , Masculino , Escalas de Graduação Psiquiátrica , Esquizofrenia/complicações , Esquizofrenia/epidemiologia , Caracteres Sexuais
15.
Front Psychol ; 12: 634133, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34366961

RESUMO

Time pressure (TP) is the most common kind of pressure faced by R&D teams. How to improve team innovation performance (TIP) when time resources are insufficient has been a concern of practitioners and scholars. The purpose of this paper is to put forward some suggestions to solve that time dilemma. We conducted a survey based on a sample of 163 teams. In the first-stage survey (time 1), we measured the team temporal leadership (TTL) and TP. In the second-stage survey (time 2), we measured team learning behavior (TLB). TIP was measured in the third-wave survey (time 3). The results are as follows: (i) TTL has a significant positive impact on the TLB and TIP; (ii) TLB plays a mediating role in the relationship between TTL and TIP; and (iii) TP can positively moderate the relationship between TTL and TLB, that is, the promoting effect of TTL on TLB is more pronounced under the higher level of TP. These findings reveal the influence mechanism of TTL on TIP from the perspective of TLB and TP.

16.
Nucleic Acids Res ; 49(4): 2027-2043, 2021 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-33476374

RESUMO

Dysfunction of splicing factors often result in abnormal cell differentiation and apoptosis, especially in neural tissues. Mutations in pre-mRNAs processing factor 31 (PRPF31) cause autosomal dominant retinitis pigmentosa, a progressive retinal degeneration disease. The transcriptome-wide splicing events specifically regulated by PRPF31 and their biological roles in the development and maintenance of retina are still unclear. Here, we showed that the differentiation and viability of retinal progenitor cells (RPCs) are severely perturbed in prpf31 knockout zebrafish when compared with other tissues at an early embryonic stage. At the cellular level, significant mitotic arrest and DNA damage were observed. These defects could be rescued by the wild-type human PRPF31 rather than the disease-associated mutants. Further bioinformatic analysis and experimental verification uncovered that Prpf31 deletion predominantly causes the skipping of exons with a weak 5' splicing site. Moreover, genes necessary for DNA repair and mitotic progression are most enriched among the differentially spliced events, which may explain the cellular and tissular defects in prpf31 mutant retinas. This is the first time that Prpf31 is demonstrated to be essential for the survival and differentiation of RPCs during retinal neurogenesis by specifically modulating the alternative splicing of genes involved in DNA repair and mitosis.


Assuntos
Processamento Alternativo , Células-Tronco Neurais/metabolismo , Neurogênese/genética , Retina/embriologia , Proteínas de Peixe-Zebra/fisiologia , Animais , Apoptose , Sistemas CRISPR-Cas , Sobrevivência Celular , Dano ao DNA , Reparo do DNA , Éxons , Técnicas de Inativação de Genes , Pontos de Checagem da Fase M do Ciclo Celular , Células-Tronco Neurais/citologia , Neurônios Retinianos/citologia , Neurônios Retinianos/metabolismo , Fuso Acromático/ultraestrutura , Proteína Supressora de Tumor p53/metabolismo , Peixe-Zebra/embriologia , Peixe-Zebra/genética , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismo
17.
FASEB J ; 34(9): 11997-12008, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32738093

RESUMO

Hematopoietic stem and progenitor cells (HSPCs) have the ability to self-renew and differentiate into various blood cells, thus playing an important role in maintenance of lifelong hematopoiesis. Brahma-related gene 1 (BRG1), which acts as the ATP subunit of mammalian SWI-SNF-related chromatin remodeling complexes, is involved in human acute myeloid leukemia and highly expresses in short-term HSPCs. But its role and regulatory mechanism for HSPC development have not yet been well established. Here, we generated a brg1 knockout zebrafish model using TALEN technology. We found that in brg1-/- embryo, the primitive hematopoiesis remained well, while definitive hematopoiesis formation was significantly impaired. The number of hemogenic endothelial cells was decreased, further affecting definitive hematopoiesis with reduced myeloid and lymphoid cells. During embryogenesis, the nitric oxide (NO) microenvironment in brg1-/- embryo was seriously damaged and the reduction of HSPCs could be partially rescued by a NO donor. Chromatin immunoprecipitation (ChIP) assays showed that BRG1 could bind to the promoter of KLF2 and trigger its transcriptional activity of NO synthase. Our findings show that Brg1 promotes klf2a expression in hemogenic endothelium and highlight a novel mechanism for HSPC formation and maintenance.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Embrião não Mamífero/embriologia , Hematopoese , Células-Tronco Hematopoéticas/metabolismo , Nicho de Células-Tronco , Proteínas de Peixe-Zebra/metabolismo , Peixe-Zebra/embriologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Regulação da Expressão Gênica no Desenvolvimento , Técnicas de Inativação de Genes , Células-Tronco Hematopoéticas/citologia , Fatores de Transcrição Kruppel-Like/biossíntese , Fatores de Transcrição Kruppel-Like/genética , Óxido Nítrico/genética , Óxido Nítrico/metabolismo , Elementos de Resposta , Transcrição Gênica , Peixe-Zebra/genética , Proteínas de Peixe-Zebra/biossíntese , Proteínas de Peixe-Zebra/genética
18.
Turk J Chem ; 44(5): 1430-1444, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33488242

RESUMO

Polydioxanone (PPDO) is synthesized by ring-opening polymerization of p-dioxanone, using stannous octoate as the catalyst. The polarized optical micrograph (POM) shows thes pherulite growth rate of PPDO decreases with an increase in the isothermal crystallization temperature. PPDO is compression-molded into bars, and PPDO bars are subjected to isothermal annealing at a range of temperatures (Ta = 50, 60, 70, 80, 90, and 100 °C), and correspond to three different annealing times (ta = 1h, 2h, 3h). The effect on PPDO is investigated by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). With an increase in Ta and ta, the grain size and the degree of crystallinity also increase. Meanwhile, the tensile strength is significantly improved. The PPDO bars (90 °C, 2 h) reach the maximum crystallinity (57.21%) and the maximum tensile strength (41.1 MPa). Interestingly, the heat treatment process does not result in serious thermal degradation. It is observed that the hydrolytic degradation of the annealed PPDO is delayed to some extent. Thus, annealed PPDO might have potential applications, particularly in the fields of orthopedic fixation and tissue engineering.

20.
J Biol Chem ; 294(38): 13953-13963, 2019 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-31362982

RESUMO

Mutations in human prominin 1 (PROM1), encoding a transmembrane glycoprotein localized mainly to plasma membrane protrusions, have been reported to cause retinitis pigmentosa, macular degeneration, and cone-rod dystrophy. Although the structural role of PROM1 in outer-segment (OS) morphogenesis has been demonstrated in Prom1-knockout mouse, the mechanisms underlying these complex disease phenotypes remain unclear. Here, we utilized a zebrafish model to further investigate PROM1's role in the retina. The Prom1 orthologs in zebrafish include prom1a and prom1b, and our results showed that prom1b, rather than prom1a, plays an important role in zebrafish photoreceptors. Loss of prom1b disrupted OS morphogenesis, with rods and cones exhibiting differences in impairment: cones degenerated at an early age, whereas rods remained viable but with an abnormal OS, even at 9 months postfertilization. Immunofluorescence experiments with WT zebrafish revealed that Prph2, an ortholog of the human transmembrane protein peripherin 2 and also associated with OS formation, is localized to the edge of OS and is more highly expressed in the cone OS than in the rod OS. Moreover, we found that Prom1b deletion causes mislocalization of Prph2 and disrupts its oligomerization. We conclude that the variation in Prph2 levels between cones and rods was one of the reasons for the different PROM1 mutation-induced phenotypes of these retinal structures. These findings expand our understanding of the phenotypes caused by PROM1 mutations and provide critical insights into its function.


Assuntos
Antígeno AC133/metabolismo , Células Fotorreceptoras/metabolismo , Segmento Externo da Célula Bastonete/metabolismo , Antígeno AC133/genética , Animais , Distrofias de Cones e Bastonetes/genética , Modelos Animais de Doenças , Células HeLa , Humanos , Degeneração Macular/metabolismo , Proteínas de Membrana/metabolismo , Morfogênese , Mutação , Periferinas/genética , Retina/metabolismo , Retina/fisiologia , Células Fotorreceptoras Retinianas Cones/metabolismo , Degeneração Retiniana/genética , Degeneração Retiniana/fisiopatologia , Células Fotorreceptoras Retinianas Bastonetes/metabolismo , Retinose Pigmentar/genética , Deleção de Sequência , Peixe-Zebra/metabolismo , Proteínas de Peixe-Zebra/metabolismo
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