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1.
ACS Sustain Chem Eng ; 12(19): 7246-7255, 2024 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-38757124

RESUMO

Aliphatic polyesters have received considerable attention in recent years due to their biodegradability and biocompatible, mechanical, and thermal properties that can make them a suitable alternative to today's commercialized polymers. The ring-opening copolymerization (ROCOP) of epoxides and cyclic anhydrides is a route to synthesize a diverse array of polyesters that could be useful in many applications. However, the catalysts used rarely consider biocompatible catalysts in the case that any are left in the polymer. To the best of our knowledge, we report the first example of using deep eutectic solvents (DESs) as biocompatible catalysts for this target ROCOP with polymerization activity for at least six diverse monomer pairs. Choline halide salts are active for this polymerization, with dried salts showing polymerization slower than that of those conducted in air. Hydrogen bonding with water is hypothesized to enhance the rate-determining step of epoxide ring opening. While the presence of water improves the rate of polymerization, it also acts as a chain transfer agent, leading to smaller molar mass polymers than intended. Combining the choline halide salts with urea or ethylene glycol hydrogen bond donors in air led to DES catalysts that reacted similarly to the salts exposed to air. However, when generating these DESs in air-free conditions, they showed similar rates of polymerization without a drop in polymer molar mass. The hydrogen bonding provided by urea and ethylene glycol seems to promote the rate increase without serving as a chain transfer agent. Results reported herein display the promising potential of biocompatible catalyst systems for this ROCOP process as well as introducing the use of hydrogen bonding to enhance polymerization rates.

2.
ACS Chem Biol ; 19(3): 707-717, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38442242

RESUMO

Surface lipids on pathogenic mycobacteria modulate infection outcomes by regulating host immune responses. Phenolic glycolipid (PGL) is a host-modulating surface lipid that varies among clinical Mycobacterium tuberculosis strains. PGL is also found in Mycobacterium marinum, where it promotes infection of zebrafish through effects on the innate immune system. Given the important role this lipid plays in the host-pathogen relationship, tools for profiling its abundance, spatial distribution, and dynamics are needed. Here, we report a strategy for imaging PGL in live mycobacteria using bioorthogonal metabolic labeling. We functionalized the PGL precursor p-hydroxybenzoic acid (pHB) with an azide group (3-azido pHB). When fed to mycobacteria, 3-azido pHB was incorporated into the cell surface, which could then be visualized via the bioorthogonal conjugation of a fluorescent probe. We confirmed that 3-azido pHB incorporates into PGL using mass spectrometry methods and demonstrated selectivity for PGL-producing M. marinum and M. tuberculosis strains. Finally, we applied this metabolic labeling strategy to study the dynamics of PGL within the mycobacterial membrane. This new tool enables visualization of PGL that may facilitate studies of mycobacterial pathogenesis.


Assuntos
Mycobacterium marinum , Mycobacterium tuberculosis , Animais , Glicolipídeos/metabolismo , Fatores de Virulência/metabolismo , Peixe-Zebra , Mycobacterium tuberculosis/metabolismo , Mycobacterium marinum/metabolismo
3.
Eur J Med Res ; 29(1): 192, 2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38528598

RESUMO

BACKGROUND: Current evidence from epidemiologic studies suggested that phthalate metabolites might be associated with blood pressure (BP) changes. However, the special relationship between phthalate metabolites and BP changes in children has not been clearly elucidated in existing researches. OBJECTIVES: We investigated the links between phthalate metabolites and various BP parameters, including systolic/diastolic BP, mean arterial pressure (MAP), and the presence of hypertension. METHODS: The population sample consisted of 1036 children aged 8 to 17 years from the 2013-2018 NHANES in the United States. High performance liquid chromatography-electrospray ionization-tandem mass spectrometry was used to measure urinary concentrations of 19 phthalate metabolites. Systolic/diastolic BP were derived from the average of three valid measurements, and MAP was calculated as (systolic BP + 2 × diastolic BP)/3. Hypertension was defined as mean systolic BP and/or diastolic BP that was ≥ 95th percentile for gender, age, and height reference. Linear regression, logistic regression, and weighted quantile sum (WQS) regression models were employed to assess the associations between phthalate exposure and systolic/diastolic BP, MAP, and hypertension. RESULTS: Ten of 19 phthalate metabolites including MCNP, MCOP, MECPP, MBP, MCPP, MEP, MEHHP, MiBP, MEOHP, and MBzP had detection frequencies > 85% with samples more than 1000. MCNP, MCOP, MECPP, MBP, MCPP, MEHHP, MiBP, MEOHP, and MBzP were generally negatively associated with systolic/diastolic BP and MAP, but not protective factors for hypertension. These associations were not modified by age (8-12 and 13-17 years) or sex (boys and girls). The above-mentioned associations were further confirmed by the application of the WQS analysis, and MCOP was identified as the chemical with the highest weight. CONCLUSION: Phthalate metabolites were associated with modest reductions in systolic/diastolic BP, and MAP in children, while appeared not protective factors for hypertension. Given the inconsistent results among existing studies, our findings should be confirmed by other cohort studies.


Assuntos
Poluentes Ambientais , Hipertensão , Ácidos Ftálicos , Masculino , Criança , Feminino , Humanos , Estados Unidos/epidemiologia , Exposição Ambiental , Poluentes Ambientais/urina , Pressão Sanguínea , Inquéritos Nutricionais , Ácidos Ftálicos/metabolismo , Hipertensão/induzido quimicamente , Hipertensão/epidemiologia
4.
J Lipid Res ; : 100533, 2024 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-38522749

RESUMO

Mycobacterial plasma membrane, together with the peptidoglycan-arabinogalactan cell wall and waxy outer membrane, creates a robust permeability barrier against xenobiotics. The fact that several anti-tuberculosis drugs target plasma membrane-embedded enzymes underscores the importance of the plasma membrane in bacterial physiology and pathogenesis. Nevertheless, its accurate phospholipid composition remains undefined, with conflicting reports on the abundance of phosphatidylinositol mannosides (PIMs), physiologically important glycolipids evolutionarily conserved among mycobacteria and related bacteria. Some studies indicate cardiolipin, phosphatidylethanolamine, and phosphatidylinositol as dominant structural phospholipids. Conversely, some suggest PIMs dominate the plasma membrane. A striking example of the latter is the use of reverse micelle extraction, showing diacyl phosphatidylinositol dimannoside (Ac2PIM2) as the most abundant phospholipid in a model organism, Mycobacterium smegmatis. Our recent work reveals a rapid response mechanism to membrane-fluidizing stress in mycobacterial plasma membrane: monoacyl phosphatidylinositol dimannoside and hexamannoside (AcPIM2 and AcPIM6), are converted to diacyl forms (Ac2PIM2 and Ac2PIM6). Given the dynamic nature of PIMs, we aimed to resolve the conflicting data in the literature. We show that unstressed M. smegmatis lacks an Ac2PIM2-dominated plasma membrane. Ac2PIM2 accumulation is induced by experimental conditions involving sodium docusate, a component of the reverse micellar solution. Using chemically synthesized PIMs as standards, we accurately quantified phospholipid ratio in M. smegmatis through liquid chromatography-mass spectrometry, revealing that mycobacterial plasma membrane is dominated by cardiolipin, phosphatidylethanolamine, and phosphatidylinositol. Thus, PIMs are quantitatively minor but responsive to environmental stresses in M. smegmatis. Our study paves the way for accurate modeling of mycobacterial plasma membrane.

5.
Regen Biomater ; 11: rbae010, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38414795

RESUMO

Acellular dermal matrix (ADM) shows promise for cartilage regeneration and repair. However, an effective decellularization technique that removes cellular components while preserving the extracellular matrix, the transformation of 2D-ADM into a suitable 3D scaffold with porosity and the enhancement of bioactive and biomechanical properties in the 3D-ADM scaffold are yet to be fully addressed. In this study, we present an innovative decellularization method involving 0.125% trypsin and 0.5% SDS and a 1% Triton X-100 solution for preparing ADM and converting 2D-ADM into 3D-ADM scaffolds. These scaffolds exhibit favorable physicochemical properties, exceptional biocompatibility and significant potential for driving cartilage regeneration in vitro and in vivo. To further enhance the cartilage regeneration potential of 3D-ADM scaffolds, we incorporated porcine-derived small intestinal submucosa (SIS) for bioactivity and calcium sulfate hemihydrate (CSH) for biomechanical reinforcement. The resulting 3D-ADM+SIS scaffolds displayed heightened biological activity, while the 3D-ADM+CSH scaffolds notably bolstered biomechanical strength. Both scaffold types showed promise for cartilage regeneration and repair in vitro and in vivo, with considerable improvements observed in repairing cartilage defects within a rabbit articular cartilage model. In summary, this research introduces a versatile 3D-ADM scaffold with customizable bioactive and biomechanical properties, poised to revolutionize the field of cartilage regeneration.

6.
Ecotoxicol Environ Saf ; 271: 115952, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38218109

RESUMO

Cigarette smoking is one of the most impactful behavior-related risk factors for multiple cancers including hepatocellular carcinoma (HCC). Nicotine, as the principal component of tobacco, is not only responsible for smoking addiction but also a carcinogen; nevertheless, the underlying mechanisms remain unclear. Here we report that nicotine enhances HCC cancer stemness and malignant progression by upregulating the expression of GC-rich binding factor 2 (GCF2), a gene that was revealed to be upregulated in HCC and whose upregulation predicts poor prognosis, and subsequently activating the Wnt/ꞵ-catenin/SOX2 signaling pathway. We found that nicotine significantly increased GCF2 expression and that silencing of GCF2 reduced nicotine-induced cancer stemness and progression. Mechanistically, nicotine could stabilize the protein level of GCF2, and then GCF2 could robustly activate its downstream Wnt/ß-catenin signaling pathway. Taken together, our results thus suggest that GCF2 is a potential target for a therapeutic strategy against nicotine-promoted HCC.


Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Humanos , Carcinoma Hepatocelular/induzido quimicamente , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/induzido quimicamente , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , Nicotina/toxicidade , Linhagem Celular Tumoral , Via de Sinalização Wnt/genética , Regulação Neoplásica da Expressão Gênica , Proliferação de Células
7.
Cell ; 186(21): 4583-4596.e13, 2023 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-37725977

RESUMO

The CD1 system binds lipid antigens for display to T cells. Here, we solved lipidomes for the four human CD1 antigen-presenting molecules, providing a map of self-lipid display. Answering a basic question, the detection of >2,000 CD1-lipid complexes demonstrates broad presentation of self-sphingolipids and phospholipids. Whereas peptide antigens are chemically processed, many lipids are presented in an unaltered form. However, each type of CD1 protein differentially edits the self-lipidome to show distinct capture motifs based on lipid length and chemical composition, suggesting general antigen display mechanisms. For CD1a and CD1d, lipid size matches the CD1 cleft volume. CD1c cleft size is more variable, and CD1b is the outlier, where ligands and clefts show an extreme size mismatch that is explained by uniformly seating two small lipids in one cleft. Furthermore, the list of compounds that comprise the integrated CD1 lipidome supports the ongoing discovery of lipid blockers and antigens for T cells.


Assuntos
Antígenos CD1 , Lipídeos , Humanos , Apresentação de Antígeno , Antígenos CD1/química , Antígenos CD1/metabolismo , Lipidômica , Lipídeos/química , Linfócitos T , Motivos de Aminoácidos
8.
World J Clin Cases ; 11(20): 4912-4919, 2023 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-37584000

RESUMO

BACKGROUND: The clinical symptoms and imaging manifestations of neurocysticercosis (NCC) are very different, and the difficulty and delay of clinical diagnoses may lead to an increase in mortality and disability. Rapid and accurate pathogen identification is important for the treatment of these patients. Metagenomic next-generation sequencing (mNGS) is a powerful tool to identify pathogens, especially in infections that are difficult to identify by conventional methods. CASE SUMMARY: A 43-year-old male patient was admitted due to a recurrent headache for a few months. Imaging examinations showed hydrocephalus and cystic lesions, which were considered to be a central nervous system infection, but no etiology was found by routine examination. mNGS of the cerebrospinal fluid revealed high Taenia solium reads, and the positive results of a cysticercosis antibody test confirmed the infection. Combined with the patient's clinical manifestations, the etiological evidence, and the imaging manifestation, the patient was finally diagnosed with NCC and he was prescribed dexamethasone, albendazole, neurotrophic drugs, and intracranial pressure reduction therapy. The headaches disappeared after anti-parasite treatment, and no associated symptoms recurred prior to the three- and six-month follow-up. CONCLUSION: As an accurate and sensitivity detection method, mNGS can be a reliable approach for the diagnosis of NCC.

9.
Photobiomodul Photomed Laser Surg ; 41(8): 422-428, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37523290

RESUMO

Background: To investigate the application value of 980-nm/1470-nm dual-wavelength fiber laser in thyroidectomy. Methods: The clinical data of 130 patients undergoing thyroid surgery from March 2017 to December 2018 were retrospectively analyzed. According to the use types of energy devices, the patients were divided into laser group and ultrasonic scalpel group, with 65 patients in each group. The baseline data, operation-related indicators, operation complications, postoperative pathological conditions, and follow-up results of the two groups were compared. Results: The operations were successfully completed in both groups. The median operative time of total thyroidectomy (TT), lobectomy+central lymph node dissection (CLND), TT+CLND in the laser group were longer than that in the harmonic scalpel group, and the difference was statistically significant (p < 0.05). The incidence of parathyroid gland congestion in the laser group (10.3%) was lower than that in the harmonic scalpel group (19.2%), and the difference was statistically significant (p < 0.05). No significant differences were found in operative type, intraoperative blood loss, postoperative drainage volume, operative complications, postoperative hospital stay, and lymph node metastasis rate between the two groups (p > 0.05). No incidence was noted of recurrence, metastasis, or death in both groups. Conclusions: The 980-nm/1470-nm dual-wavelength fiber laser had an efficacy in open thyroidectomy similar to that of the harmonic scalpel, was safe and feasible, and less damage to the parathyroid gland blood supply than a scalpel. It can be used as a new option for thyroid surgery.

10.
bioRxiv ; 2023 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-37292637

RESUMO

Fibroblasts play critical roles in tissue homeostasis, but in pathologic states can drive fibrosis, inflammation, and tissue destruction. In the joint synovium, fibroblasts provide homeostatic maintenance and lubrication. Little is known about what regulates the homeostatic functions of fibroblasts in healthy conditions. We performed RNA sequencing of healthy human synovial tissue and identified a fibroblast gene expression program characterized by enhanced fatty acid metabolism and lipid transport. We found that fat-conditioned media reproduces key aspects of the lipid-related gene signature in cultured fibroblasts. Fractionation and mass spectrometry identified cortisol in driving the healthy fibroblast phenotype, confirmed using glucocorticoid receptor gene ( NR3C1 ) deleted cells. Depletion of synovial adipocytes in mice resulted in loss of the healthy fibroblast phenotype and revealed adipocytes as a major contributor to active cortisol generation via Hsd11 ß 1 expression. Cortisol signaling in fibroblasts mitigated matrix remodeling induced by TNFα- and TGFß, while stimulation with these cytokines repressed cortisol signaling and adipogenesis. Together, these findings demonstrate the importance of adipocytes and cortisol signaling in driving the healthy synovial fibroblast state that is lost in disease.

11.
bioRxiv ; 2023 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-37292852

RESUMO

CD1 is an antigen presenting glycoprotein homologous to MHC I; however, CD1 proteins present lipid rather than peptide antigen. CD1 proteins are well established to present lipid antigens of Mycobacterium tuberculosis (Mtb) to T cells, but understanding the role of CD1-restricted immunity in vivo in response to Mtb infection has been limited by availability of animal models naturally expressing the CD1 proteins implicated in human response: CD1a, CD1b and CD1c. Guinea pigs, in contrast to other rodent models, express four CD1b orthologs, and here we utilize the guinea pig to establish the kinetics of gene and protein expression of CD1b orthologs, as well as the Mtb lipid-antigen and CD1b-restricted immune response at the tissue level over the course of Mtb infection. Our results indicate transient upregulation of CD1b expression during the effector phase of adaptive immunity that wanes with disease chronicity. Gene expression indicates that upregulation of CD1b is the result of transcriptional induction across all CD1b orthologs. We show high CD1b3 expression on B cells, and identify CD1b3 as the predominant CD1b ortholog in pulmonary granuloma lesions. We identify ex vivo cytotoxic activity directed against CD1b that closely paralleled the kinetic changes in CD1b expression in Mtb infected lung and spleen. This study confirms that CD1b expression is modulated by Mtb infection in lung and spleen, leading to pulmonary and extrapulmonary CD1b-restricted immunity as a component of the antigen-specific response to Mtb infection.

12.
J Clin Invest ; 133(6)2023 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-36757797

RESUMO

Induction of lipid-laden foamy macrophages is a cellular hallmark of tuberculosis (TB) disease, which involves the transformation of infected phagolysosomes from a site of killing into a nutrient-rich replicative niche. Here, we show that a terpenyl nucleoside shed from Mycobacterium tuberculosis, 1-tuberculosinyladenosine (1-TbAd), caused lysosomal maturation arrest and autophagy blockade, leading to lipid storage in M1 macrophages. Pure 1-TbAd, or infection with terpenyl nucleoside-producing M. tuberculosis, caused intralysosomal and peribacillary lipid storage patterns that matched both the molecules and subcellular locations known in foamy macrophages. Lipidomics showed that 1-TbAd induced storage of triacylglycerides and cholesterylesters and that 1-TbAd increased M. tuberculosis growth under conditions of restricted lipid access in macrophages. Furthermore, lipidomics identified 1-TbAd-induced lipid substrates that define Gaucher's disease, Wolman's disease, and other inborn lysosomal storage diseases. These data identify genetic and molecular causes of M. tuberculosis-induced lysosomal failure, leading to successful testing of an agonist of TRPML1 calcium channels that reverses lipid storage in cells. These data establish the host-directed cellular functions of an orphan effector molecule that promotes survival in macrophages, providing both an upstream cause and detailed picture of lysosome failure in foamy macrophages.


Assuntos
Mycobacterium tuberculosis , Tuberculose , Humanos , Terpenos , Nucleosídeos , Macrófagos/microbiologia , Lipídeos , Lisossomos
13.
Nat Immunol ; 24(1): 110-122, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36550321

RESUMO

Expressed on epidermal Langerhans cells, CD1a presents a range of self-lipid antigens found within the skin; however, the extent to which CD1a presents microbial ligands from bacteria colonizing the skin is unclear. Here we identified CD1a-dependent T cell responses to phosphatidylglycerol (PG), a ubiquitous bacterial membrane phospholipid, as well as to lysylPG, a modified PG, present in several Gram-positive bacteria and highly abundant in Staphylococcus aureus. The crystal structure of the CD1a-PG complex showed that the acyl chains were buried within the A'- and F'-pockets of CD1a, while the phosphoglycerol headgroup remained solvent exposed in the F'-portal and was available for T cell receptor contact. Using lysylPG and PG-loaded CD1a tetramers, we identified T cells in peripheral blood and in skin that respond to these lipids in a dose-dependent manner. Tetramer+CD4+ T cell lines secreted type 2 helper T cell cytokines in response to phosphatidylglycerols as well as to co-cultures of CD1a+ dendritic cells and Staphylococcus bacteria. The expansion in patients with atopic dermatitis of CD4+ CD1a-(lysyl)PG tetramer+ T cells suggests a response to lipids made by bacteria associated with atopic dermatitis and provides a link supporting involvement of PG-based lipid-activated T cells in atopic dermatitis pathogenesis.


Assuntos
Dermatite Atópica , Humanos , Pele , Células de Langerhans , Antígenos CD1 , Autoantígenos/metabolismo , Staphylococcus/metabolismo , Fosfatidilgliceróis
14.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-1009199

RESUMO

OBJECTIVE@#To explore influence of external factors of wind, cold and dampness on clinical symptoms in knee osteoarthritis (KOA) patients with different constitutions of traditional Chinese medicine.@*METHODS@#A cross-sectional stratified study was performed to select 108 patients with GradeⅡKOA in Kellgren & Lawrence (K-L) classification, including 22 males and 86 females, aged from 47 to 75 years old with an average of (60.7±6.0) years old;body mass index(BMI) ranged from 17.87 to 31.22 kg·m-2 with an average of (23.80±2.86) kg·m-2. According to Classification and Judgment of TCM Physique (ZYYXH/T157-2009), the types of TCM physique were determined and divided into 4 layers according to the deficiency and actual physique. Among them, there were 24 patients without biased physique, 12 males and 12 females, aged from 51 to 73 years old with an average of(62.8±6.0) years old, BMI ranged from 17.87 to 31.14 kg·m-2 with an average of (24.32±3.25) kg·m-2;there were 46 patients with virtual bias constitution, including 7 males and 39 females, aged from 47 to 70 years old with an average of (60.0±5.8) years old, BMI ranged from 19.38 to 31.22 kg·m-2 with an average of(23.42±2.97) kg·m-2;There were 26 patients with solid bias constitution, including 2 males and 24 females, aged from 48 to 75 years old with an average of (60.4±5.8) years old, BMI ranged from 21.16 to 30.76 kg·m-2 with an average of (24.15±2.33) kg·m-2;there were 9 patients with special constitution, 1 male and 8 female, aged from 53 to 75 years old with an average of (59.8±7.5) years old, BMI ranged from 19.26 to 26.67 kg·m-2 with an average of (23.79±2.49) kg·m-2. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was used to evaluate severity of clinical symptoms. The wind-cold-dampness external factor score was calculated through the questionnaire of wind-cold-dampness syndrome scale to evaluate degree of influence of wind-cold-dampness external factor. Pearson correlation analysis and partial correlation analysis were used to calculate the correlation coefficient between severity of external factors affecting wind, cold and dampness and severity of clinical symptoms in patients with different TCM constitution stratification.@*RESULTS@#There was no statistical significance between total score of wind-cold-dampness and WOMAC score in patients with no biased constitution and special condition. Total wind-cold-dampness score of patients with virtual biased constitution was positively correlated with WOMAC stiffness score (r=0.327, P=0.032), and total wind-cold-dampness score of patients with solid biased constitution was positively correlated with WOMAC pain score (r=0.561, P=0.005) and WOMAC overall score (r=0.446, P=0.033). After further adjusting for the interaction of external factors of wind-cold-dampness, there was no statistical significance between wind-cold-dampness scores and WOMAC scores in patients with solid biased constitution. The score of dampness and pathogenic factors was positively correlated with WOMAC stiffness score (r=0.414, P=0.007).@*CONCLUSION@#The external factors of wind-cold dampness have different effects on the clinical symptoms of KOA patients with different TCM constitutions. Compared with other constitutions, the rigid symptoms of patients with asthenic biased constitutions are more susceptible to dampness pathogenic factors.


Assuntos
Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Transversais , Medicina Tradicional Chinesa , Osteoartrite do Joelho , Síndrome , Vento , Temperatura Baixa
15.
Acta Biomater ; 153: 614-629, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36162767

RESUMO

Additively manufactured biodegradable zinc (Zn) alloy scaffolds constitute an important branch in orthopedic implants because of their moderate degradation behavior and bone-mimicking mechanical properties. This work investigated the corrosion fatigue response of a zinc-magnesium (Zn-Mg) alloy gyroid scaffold fabricated via laser-powder-bed-fusion additive manufacturing at the first time. The high-cycle compression-compression fatigue testing of the printed Zn-Mg scaffold was conducted in simulated body fluid, showing its favorable fatigue strength, structural reliability, and anti-fatigue capability. The printed Zn-Mg scaffold obtained a 227% higher fatigue strength than that of the printed Zn scaffold but 17% lower strain accumulation at 106 cycles. The accumulative strain of the Zn-Mg scaffold at its fatigue strength was dominant by fatigue ratcheting, since the fatigue damage strain of the scaffold was approximately zero. The corrosion products (ZnO and Zn(OH)2) were conducive to the inhibition of fatigue ratcheting and fatigue damage. Dislocation pile-up and solid solution phases at the grain boundaries of the Zn-Mg scaffold could retard the spreading of the crack tip and impede excessive grain coarsening, improving its fatigue endurance limit. Notably, the printed Zn-Mg scaffold could dissipate the fatigue energy through moderate grain boundary migration, thus reducing its plastic deformation. These findings illuminated the anti-fatigue mechanisms related to microstructural features and corrosive environments and highlighted the promising prospects of additively manufactured Zn-Mg scaffolds in orthopedic applications. STATEMENT OF SIGNIFICANCE: Additive manufacturing (AM) of biodegradable metals shows unprecedented prospects for bone tissue regeneration medicine. The corrosion fatigue property is one of the key determinants in the performance of AM biodegradable scaffolds. In this study, a Zn-Mg gyroid scaffold was additively manufactured with admirable fatigue endurance limit and anti-fatigue capability. We reported that the corrosion fatigue performance was highly relevant to the microstructural features, validating that the grain boundary engineering strategy improved fatigue strength and inhibited crack penetration. Notably, moderate grain boundary migration could dissipate fatigue energy and reduce plastic deformation. Furthermore, corrosion products were conducive to impeding fatigue ratcheting and fatigue damage, indicating the promising potential of AM Zn-Mg scaffolds in treating load-bearing bone defects.


Assuntos
Magnésio , Zinco , Magnésio/farmacologia , Magnésio/química , Corrosão , Zinco/farmacologia , Zinco/química , Reprodutibilidade dos Testes , Ligas/farmacologia , Ligas/química , Teste de Materiais , Plásticos , Implantes Absorvíveis , Materiais Biocompatíveis/farmacologia , Materiais Biocompatíveis/química
16.
Polymers (Basel) ; 14(12)2022 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-35745919

RESUMO

In this study, for the first time, a forward-rotating roller is proposed for the spreading of CF/PA12 composite powder in the selective laser sintering (SLS) process. The mesoscopic kinetic mechanism of composite particle spreading is investigated by utilizing the "multi-spherical" element within the discrete element method (DEM). The commercial software EDEM and the open-source DEM particle simulation code LIGGGHTS-PUBLIC are used for the simulations in this work. It is found that the forward-rotating roller produces a strong compaction on the powder pile than does the conventional counter-rotating roller, thus increasing the coordination number and mass flow rate of the particle flow, which significantly improves the powder bed quality. In addition, the forward-rotating pattern generates a braking friction force on the particles in the opposite direction to their spread, which affects the particle dynamics and deposition process. Therefore, appropriately increasing the roller rotation speed to make this force comparable to the roller dragging force could result in faster deposition of the composite particles to form a stable powder bed. This mechanism allows the forward-rotating roller to maintain a good powder bed quality, even at a high spreading speed, thus providing greater potential for the industry to improve the spreading efficiency of the SLS process.

17.
mBio ; 13(3): e0133222, 2022 06 28.
Artigo em Inglês | MEDLINE | ID: mdl-35695454

RESUMO

In the initial stage of respiratory infection, Mycobacterium tuberculosis traverses from alveolar macrophages to phenotypically diverse monocyte-derived phagocytes and neutrophils in the lung parenchyma. Here, we compare the in vivo kinetics of early bacterial growth and cell-to-cell spread of two strains of M. tuberculosis: a lineage 2 strain, 4334, and the widely studied lineage 4 strain H37Rv. Using flow cytometry, live cell sorting of phenotypic subsets, and quantitation of bacteria in cells of the distinct subsets, we found that 4334 induces less leukocyte influx into the lungs but demonstrates earlier population expansion and cell-to-cell spread. The earlier spread of 4334 to recruited cells, including monocyte-derived dendritic cells, is accompanied by earlier and greater magnitude of CD4+ T cell activation. The results provide evidence that strain-specific differences in interactions with lung leukocytes can shape adaptive immune responses in vivo. IMPORTANCE Tuberculosis is a leading infectious disease killer worldwide and is caused by Mycobacterium tuberculosis. After exposure to M. tuberculosis, outcomes range from apparent elimination to active disease. Early innate immune responses may contribute to differences in outcomes, yet it is not known how bacterial strains alter the early dynamics of innate immune and T cell responses. We infected mice with distinct strains of M. tuberculosis and discovered striking differences in innate cellular recruitment, cell-to-cell spread of bacteria in the lungs, and kinetics of initiation of antigen-specific CD4 T cell responses. We also found that M. tuberculosis can spread beyond alveolar macrophages even before a large influx of inflammatory cells. These results provide evidence that distinct strains of M. tuberculosis can exhibit differential kinetics in cell-to-cell spread which is not directly linked to early recruitment of phagocytes but is subsequently linked to adaptive immune responses.


Assuntos
Mycobacterium tuberculosis , Tuberculose , Animais , Imunidade Inata , Pulmão/microbiologia , Macrófagos Alveolares , Camundongos , Tuberculose/microbiologia
18.
Inorg Chem ; 61(18): 7088-7094, 2022 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-35483671

RESUMO

Monometallic yttrium ß-diketiminate complexes are active and controlled catalysts for perfectly alternating ring-opening copolymerization of 1-butene oxide and phthalic anhydride under mild conditions. ß-Diketiminate ligands with pendant neutral donors were targeted to identify both the impact of donor strength and number of donors on rates of polymerization and the presence of undesirable side reactions. Initiating groups were also varied between alkyls, chlorides, and alkoxides. In the presence of a cocatalyst, the catalysts studied were active for polymerization with minimal side reactions, whereas lack of cocatalysts led to competing homopolymerization of epoxides. While a greater donor strength and a larger number of donors both increase the rate of polymerization, donor strength generally had a bigger impact when a cocatalyst was used. Additionally, alkoxide and chloride initiators proved to be the fastest, with alkyls being more sluggish. These subtle ligand changes significantly impacting polymerization activity lend promise to the facile tunability of rare earth metal complexes to be highly active for the target copolymerization, which renders further research in this area attractive and timely.

19.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-939542

RESUMO

Based on the clinical needs and examination requirements of standardized training students, the China national standardized training textbook Acupuncture and Moxibustion for residents of traditional Chinese medicine has made innovations in the textbook content and form. In the part of meridians and acupoints, the classic original text is introduced and the main indications and operation methods of 200 commonly-used acupoints are summarized in the form of tables. In the part of acupuncture and moxibustion technique, the operating procedures are standardized and the core technical points of 20 commonly-used acupuncture and moxibustion techniques are summarized in the form of flow chart. In the part of acupuncture and moxibustion treatment, 48 typical diseases are introduced in the form of case discussion, highlighting the problem orientation and demonstrating the diagnosis and treatment procedures.


Assuntos
Humanos , Acupuntura/educação , Terapia por Acupuntura , China , Medicina Tradicional Chinesa , Moxibustão
20.
Artigo em Inglês | WPRIM (Pacífico Ocidental) | ID: wpr-927463

RESUMO

INTRODUCTION@#This study aimed to identify risk factors that are associated with increased mortality that could prompt a serious illness conversation (SIC) among patients with chronic kidney disease (CKD).@*METHODS@#The electronic health records of adult CKD patients admitted between August 2018 and February 2020 were retrospectively reviewed to identify CKD patients with >1 hospitalisation and length of hospital stay ≥4 days. Outcome measures were mortality and the duration of hospitalisation. We also assessed the utility of the Cohen's model to predict 6-month mortality among CKD patients.@*RESULTS@#A total of 442 patients (mean age 68.6 years) with median follow-up of 15.3 months were identified. The mean (standard deviation) Charlson Comorbidity Index [CCI] was 6.8±2.0 with 48.4% on chronic dialysis. The overall mortality rate until August 2020 was 36.7%. Mortality was associated with age (hazard ratio [HR] 1.51, 95% confidence interval [CI] 1.29-1.77), CCI≥7 (1.58, 1.08-2.30), lower serum albumin (1.09, 1.06-1.11), readmission within 30-day (1.96, 1.43-2.68) and CKD non-dialysis (1.52, 1.04-2.17). Subgroup analysis of the patients within first 6-month from index admission revealed longer hospitalisation stay for those who died (CKD-non dialysis: 5.5; CKD-dialysis: 8.0 versus 4 days for those survived, P<0.001). The Cohen's model demonstrated reasonable predictive ability to discriminate 6-month mortality (area under the curve 0.81, 95% CI 0.75-0.87). Only 24 (5.4%) CKD patients completed advanced care planning.@*CONCLUSION@#CCI, serum albumin and recent hospital readmission could identify CKD patients at higher risk of mortality who could benefit from a serious illness conversation.


Assuntos
Adulto , Idoso , Humanos , Registros Eletrônicos de Saúde , Hospitalização , Tempo de Internação , Insuficiência Renal Crônica/terapia , Estudos Retrospectivos
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