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1.
BMC Public Health ; 23(1): 821, 2023 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-37143051

RESUMO

BACKGROUND: The low birth rates and rapid population aging has drawn considerable attention from scholars and policymakers in China and around the world. In 2021, China launched the policy and supportive measures that allow up to 3 children per couple. This study aims to explore the influencing factors of the third-child fertility intention among women aged 20-34 years in China. METHODS: We draw data from the National Fertility Survey conducted in 2017. The nationally representative survey adopts a stratified, 3-stage, and probabilities proportional to size sampling method. A total of 61,588 valid samples aged 20-34 years old were obtained. Fertility desire and behavior, childbearing and service use, and potential influencing factors of fertility intention such as the history of pregnancy were assessed. RESULTS: In general, 5.01% of Chinese women of prime childbearing age had fertility intention for a third child, and the proportion varies by region across mainland China. Individual characteristics such as being ethnic minorities, being rural residents, and having more siblings are significantly positively correlated with the third-child fertility intention, while the intention was significantly lower among women with a higher income or education level, migrant women, and those engaged in the non-agricultural labor force. Women who already had a son had lower fertility intention for a third child. Moreover, it was the perceived acceptable costs of childcare services rather than the actual costs that mattered more for the fertility intention. CONCLUSIONS: Our study concludes a series of socioeconomic factors, and previous childbearing and childrearing experiences are crucial for women's fertility intention for a third child. These findings highlight the importance of launching supportive measures in addition to the introduction of the 3-child policy in promoting a fertility-friendly society.


Assuntos
Fertilidade , Intenção , Gravidez , Feminino , Humanos , Adulto Jovem , Adulto , Fatores Socioeconômicos , China , Coeficiente de Natalidade , Dinâmica Populacional , Países em Desenvolvimento
2.
Polymers (Basel) ; 14(7)2022 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-35406229

RESUMO

In this study, multilayer graphene oxide (GO) was used to prepare the functional layer of polyimide/GO composite membrane with polyimide (P84) used as the supporting layer. Chitosan added in the functional layer was utilized to adjust the selectivity of the composite membrane. The effects of GO and chitosan contents on membrane morphology and separation performance were investigated in detail. The composite membrane showed high rejection to Congo red and Methyl orange with high flux but low rejection to Na2SO4 and MgCl2 at 0.2 MPa and ambient temperature. The membrane exhibited excellent solvent resistance in N,N-dimethylacetamide (DMAc) after being crosslinked with 0.5 wt.% triethylene tetramine. The result means that a highly selective and solvent-resistant P84/GO composite membrane was prepared with the facile filtration preparation method.

3.
BMC Public Health ; 22(1): 444, 2022 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-35247999

RESUMO

BACKGROUND: The prevalence of tooth loss varies across the globe among oldest-old individuals. The presence of fewer than 20 teeth in old age was associated with a decrease in people's health and quality of life. This paper explored the association between socioeconomics, health-related factors, and tooth loss among the population over the age of 80 in China. METHODS: The tooth loss status of older Chinese adults was collected with a structured questionnaire from the 8th wave of the Chinese Longitudinal Healthy Longevity Survey (CLHLS). A total of 6716 individuals aged 80 years and above were included. Logistic regression was used to assess the association between socioeconomic statuses, dietary intake at approximately 60 years old, health-related factors, and tooth loss. RESULTS: Of the 6716 individuals aged 80 years and above, the composition of the group with fewer teeth for both men and women was statistically significant in many ways. Multivariate logistic regression analyses show that for men, being older than 90 years and being ADL disabled (adjusted OR: 1.71, 95% CI: 1.01-2.89) are factors that are significantly and consistently associated with a higher risk of having fewer than 20 teeth, while having a higher household income per capita (adjusted OR: 0.56, 95% CI: 0.32-0.99) decreases the risk. For women, an age of above 95 years, brushing teeth less than once per day (adjusted OR: 1.96, 95% CI: 1.26-3.03), consuming sugar some of the time as opposed to less than once per month at approximately 60 years old (adjusted OR = 1.74, 95% CI: 1.15-2.62), and being ADL disabled (adjusted OR: 1.70, 95% CI: 1.04-2.77) are factors that are significantly associated with the risk of having fewer than 20 teeth. CONCLUSION: The analysis suggests that socioeconomic status, dietary intake in early old age, and ADL capacity are associated with the risk of having fewer teeth for the population aged 80 years and above, and the risk factors vary between sexes.


Assuntos
Perda de Dente , Adulto , Idoso , Idoso de 80 Anos ou mais , Pré-Escolar , China/epidemiologia , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Qualidade de Vida , Fatores de Risco , Fatores Socioeconômicos , Perda de Dente/epidemiologia
4.
RSC Adv ; 13(1): 615-623, 2022 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-36605644

RESUMO

Fabrication of a dense polymer/ceramic composite membrane with high permeability remains a great challenge. In this study, a highly selective polydopamine (PDA)/ceramic composite nanofiltration (NF) membrane was prepared by using an Al2O3 ceramic membrane with pore size of 0.1 µm as the support layer. In order to improve the membrane formation rate, KMnO4 was introduced to oxidize the dopamine to improve the reactivity, and Na2CO3 was used to adjust the pH value of the dopamine solution. When the addition amount of KMnO4 is 0.2 g L-1 and that of Na2CO3 is 1 g L-1, a functional layer can be formed within 10 min. PDA and polyethyleneimine (PEI) were added to the functional layer to adjust the selectivity of the composite membrane. The composite membrane showed a rejection of 99.7% towards Congo red dye with a high flux of 165 L (m2 h bar)-1 at ambient temperature. After 3 h treatment with Congo red, the fouling resistance of the membrane was improved compared with that of the ceramic based membrane. The surface morphology and composition of the composite membrane were also characterized with scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), which confirmed the successful preparation of the PDA/ceramic composite membrane.

5.
Nanomaterials (Basel) ; 11(12)2021 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-34947520

RESUMO

SSZ-13, with a unique pore structure and excellent thermal stability, showed a potential application in the adsorption and catalysis industry. In this work, Al(NO3)3 was used as an Al source to study the performance and morphology of the zeolite. The zeolite was prepared with an unconventional process by adding an Al source before the structure-directing agent and base. When inorganic oxygen-containing anions were introduced into the unconventional synthesis system, the crystals of the zeolite conform to the unconventional growth mode. The zeolites with large crystals were assembled from small unit nanocrystals. Extending the reaction time, aging time and adding fluoride ions introduced a multistage pore structure on the surface of the molecular sieve, which improved the CO2 adsorption performance. When aging for 24 h, reaction for 96 h, and the amount of fluorine added was 0.05 (F/Si), the sample had the best hierarchical pore structure. The SSZ-13 molecular sieve with an added amount of 0.1 (F/Si) has the highest CO2 adsorption performance. The adsorption amount was 4.55 mmol/g at 1 bar, which is 20.4% higher than that of zeolite SSZ-13 prepared by the conventional process.

6.
J Immunol Res ; 2021: 2185568, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34765679

RESUMO

We recently showed that both nontypeable Haemophilus influenzae (NTHi) and its surface plasminogen- (Plg-) binding proteins interact with lipoprotein(a) (Lp(a)) in a lysine-dependent manner. Because Lp(a) can be taken up by macrophages, we postulated that it serves as an opsonin to enhance phagocytosis of NTHi by macrophages. Based on colony-forming unit (CFU) counts, Lp(a) was found to increase U937 macrophage-mediated phagocytosis of NTHi49247 and NTHi49766 by 34% and 43%, respectively, after 120 min. In contrast, Lp(a) did not enhance phagocytosis of Escherichia coli BL21 or E. coli JM109, which were unable to bind to Lp(a). As with U937 macrophages, Lp(a) was capable of increasing phagocytosis of NTHi49247 by peripheral blood mononuclear cell-derived macrophages. Opsonic phagocytosis by Lp(a) was inhibited by the addition of recombinant kringle IV type 10 (rKIV10), a lysine-binding competitor; moreover, Lp(a) did not increase phagocytosis of NTHi by U937 macrophages that were pretreated with a monoclonal antibody against the scavenger receptor CD36. Taken together, our observation suggests that Lp(a) might serve as a lysine-binding opsonin to assist macrophages in rapid recognition and phagocytosis of NTHi.


Assuntos
Infecções por Haemophilus/metabolismo , Haemophilus influenzae/patogenicidade , Lipoproteína(a)/metabolismo , Macrófagos/metabolismo , Proteínas Opsonizantes/metabolismo , Fagocitose/fisiologia , Antígenos CD36/metabolismo , Linhagem Celular , Linhagem Celular Tumoral , Escherichia coli/patogenicidade , Infecções por Haemophilus/microbiologia , Humanos , Leucócitos Mononucleares/metabolismo , Leucócitos Mononucleares/microbiologia , Macrófagos/microbiologia , Células U937
7.
Spectrochim Acta A Mol Biomol Spectrosc ; 261: 120016, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34091356

RESUMO

Food safety has become one of the urgent affairs in the global public health studies, and irregular viscosity is closely associated with the food spoilage extent. In this study, one kind of activatable molecular rotor (TPA-PBZ) based on triphenylamine derivates has been synthesized via the Schiff base condensation reaction. This rotor is comprised by donor-accepter conjugated structure, with aggregation induced-emission feature and a large Stokes shift of 160 nm in water. The rotation of aromatic rings in TPA-PBZ is restricted in high-viscosity microenvironment, with the gradually increasing fluorescence emission signal at 568 nm. Significantly, this rotor TPA-PBZ has successfully been applied not only in the determination of thickening effects of food gum, but also in the detection of viscosity enhancement during the liquid food spoilage process. This molecular rotor can be utilized as an intelligent monitor platform for food quality and safety inspection in viscosity-related conditions.


Assuntos
Corantes Fluorescentes , Água , Espectrometria de Fluorescência , Viscosidade
8.
R Soc Open Sci ; 8(4): 201322, 2021 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-34007457

RESUMO

Hierarchical AlPO-34 molecular sieves microspheres were synthesized in a [BMIm]Br ionic liquid without template or complex post-treatment process. The formation mechanism of such framework structures and their morphology were investigated. [BMIm]Br was proven to serve as both solvent and sole provider of the structure directing agent. The organic amine in the compound affects the framework density of the crystals and promotes the formation of a chabazite (CHA) type framework. After ageing for 1 h the AlPO-34 microspheres are formed due to the aggregation properties of the ionic liquid. The hierarchical mirosphere has a relatively high Brunauer-Emmett-Teller surface area and a considerably uniform mesoporous channel network. The hierarchical AlPO-34 microspheres were used as absorbers of heavy metal cations and showed a higher loading capacity and distribution coefficient compared with the AlPO-34-NH.

9.
Transbound Emerg Dis ; 68(4): 2250-2260, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33048441

RESUMO

Anthrax is a natural foci disease in Inner Mongolia, which poses a severe threat to public health. In this study, the incidence number, rate and constituent ratio were used to describe the epidemiological characteristics of anthrax in the region from 1956-2018. The molecular correlation and genetic characteristics of the strains were investigated using canonical single nucleotide polymorphisms (CanSNP), multiple-locus variable-number tandem repeat analysis (MLVA-15) and whole genome sequencing (WGS). The epidemiological characteristics of anthrax in Inner Mongolia have altered significantly. The incidence of anthrax has decreased annually without vaccination, and the regional distribution of anthrax gradually transferred from central and western regions to the eastern. Moreover, the occupation distribution evolved from multiple early occupations to predominated by farmers and herdsmen. This change is closely related to policy factors and to changes in the means of production and the living habits of the local population. This indicates that reformulating the control and prevention strategies is essential. Both A. Br. Ames and A. Br. 001/002 subgroups were the predominant CanSNP genotypes of Bacillus anthracis in Inner Mongolia. A total of 36 strains constituted six shared MLVA-15 genotypes, suggesting an epidemiological link between the strains of each shared genotype. The six shared genotypes ([GT1, 9, 11 and 15] and [GT8 and 12]) consisting of 2-7 strains confirmed the occurrence of multiple point outbreaks and cross-regional transmission caused by multiple common sources of infection. Phylogenetic analysis based on the WGS core genome showed that strains from this study formed an independent clade (C.V.), and they were positioned close to each other, suggesting a common origin. Further comparison analysis should be performed to ascertain the geographic origin of these strains.


Assuntos
Antraz , Bacillus anthracis , Animais , Antraz/epidemiologia , Antraz/veterinária , Bacillus anthracis/genética , China/epidemiologia , Genótipo , Repetições Minissatélites/genética , Epidemiologia Molecular , Filogenia , Polimorfismo de Nucleotídeo Único
10.
Nanomaterials (Basel) ; 10(11)2020 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-33233615

RESUMO

Because of its unique eight-membered ring pore structure and the arrangement of cations in its structure, the SSZ-13 molecular sieve has a higher affinity for CO2 than other gases, meaning it has attracted more attention than other porous materials for CO2 adsorption. However, the expensive template and long preparation time limits the industrial production of SSZ-13. In this work, a hollow structure was successfully introduced into the nanosized SSZ-13 molecular sieve with ultrasonic treatment. The effects of the amount of seed added and the ultrasonic time on the structure were investigated. When the amount of seed added was 0.5 wt.% and the ultrasonic time was 60 min, the sample showed a hollow cubic crystal with a diameter of about 50 nm. The specific surface area reached 791.50 m2/g, and the mesoporous ratio was 66.3%. The samples were tested for CO2 adsorption performance at 298 K. It was found that the hollow sample prepared in this work has higher CO2 adsorption capacity compared with the SSZ-13 zeolite prepared with conventional methods. When the adsorption pressure was 0.27 bar, the adsorption amount reached 2.53 mmol/g. The hollow SSZ-13 molecular sieve reached a CO2 adsorption capacity of 4.24 mmol/g at 1 bar.

11.
ACS Omega ; 5(36): 23148-23156, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32954165

RESUMO

A polyamide composite forward osmosis (FO) hollow fiber membrane was successfully prepared with a novel copoly(phthalazinone biphenyl ether sulfone) (PPBES) polymer. Effects of different additives including ethylene glycol methyl ether (EGME) and lithium chloride anhydrous (LiCl) in the dope solution on the morphologies and properties of PPBES support membranes and composite FO hollow fiber membranes were investigated. With the increase of EGME content in the dope solution, the water flux of PPBES support membranes and FO hollow fiber membranes decreased. When LiCl was added into the dope solution, the water flux of FO hollow fiber membranes improved significantly with the increase of LiCl content. Additionally, the FO performance of the PPBES membrane was further optimized by adding triethylamine (TEA) in the interfacial polymerization (IP) process. In comparison with other FO membranes, the novel PPBES composite FO hollow fiber membrane displayed a remarkably high water flux of 45.3 L/m2 h and a low specific reverse salt flux of 0.15 g/L.

12.
Nanomaterials (Basel) ; 10(3)2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32143522

RESUMO

Nanosized Mn3O4 nanowires are prepared with KMnO4 and ethanol in mild conditions by facile hydrothermal method. Hydrothermal reaction temperature is optimized to get uniform nanowires. The prepared Mn3O4 nanowires exhibit high activity in the treatment of phenol at acid condition and room temperature. The 20 mg Mn3O4 nanowires can efficiently dispose of 50 mL phenol solution (0.2 g·L-1) at pH 2 and 25 °C. The nanowires before and after phenol treatment are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) and the reaction mechanism is discussed.

13.
J Microbiol ; 57(8): 711-716, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31089970

RESUMO

Low-density lipoprotein (LDL) was recently reported to be an opsonin, enhancing the phagocytosis of group A Streptococcus (GAS) by human monocytic leukemia U937 cells due to the binding of LDL to some GAS strains. We postulated that LDL might also promote the opsonophagocytosis of Pseudomonas aeruginosa by U937 cells since this bacterium interacts with LDL. In this study, P. aeruginosa (CMCC10104), U937 cells, and human LDL were used in phagocytosis assays to test our hypothesis. Escherichia coli strain BL21, which does not interact with LDL, was used as a negative control. Colony counting and fluorescence microscopy were used to determine the bacterial quantity in the opsonophagocytosis assays. After incubation of U937 cells and P. aeruginosa with LDL (100 µg/ml) for 15 and 30 min, phagocytosis was observed to be increased by 22.71% and 32.90%, respectively, compared to that seen in the LDL-free group. However, LDL did not increase the phagocytosis of E. coli by U937 cells. In addition, we identified CD36 as a major opsonin receptor on U937 cells, since an anti-CD36 monoclonal antibody, but not an anti-CD4 monoclonal antibody, almost completely abolished the opsonophagocytosis of P. aeruginosa by U937 cells.


Assuntos
Anticorpos Monoclonais/imunologia , Lipoproteínas LDL , Proteínas Opsonizantes/imunologia , Fagocitose , Pseudomonas aeruginosa/imunologia , Escherichia coli/metabolismo , Humanos , Lipoproteínas LDL/imunologia , Lipoproteínas LDL/farmacologia , Fagocitose/efeitos dos fármacos , Fagocitose/imunologia , Células U937
14.
Med Microbiol Immunol ; 205(2): 155-62, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26392394

RESUMO

Low-density lipoprotein (LDL) binds to group A Streptococcus (GAS) through Sc11 protein, and scavenger receptor CD36 of monocyte mediates the endocytosis of native or modified LDL. Therefore, we hypothesized that LDL might be an opsonin enhancing the phagocytosis of LDL-bound GAS by monocyte. The results showed that LDL could significantly promote U937 cell to phagocytose M28 (ATCC BAA1064) and M41 (ATCC 12373, AM41)-type GAS, and the phagocytosis rates were significantly increased, compared with LDL-free group. LDL, however, did not enhance the phagocytosis of M41 (CMCC 32198, CM41) or M6 (ATCC BAA946)-type GAS since these two strains did not bind to LDL. CD36 was the major scavenger receptor mediating the uptake of LDL-bound GAS by monocyte U937 cells since anti-CD36 antibody abolished the phagocytosis of LDL-opsonized GAS but anti-CD4 antibody did not. Most of AM41-type GAS cells were killed in human blood, whereas only a few CM41-type cells were phagocytosed. Moreover, recombinant Scl1 (rScl1) derived from M41-type GAS could significantly decrease the opsonophagocytosis of AM41 but not CM41-type GAS because the rScl1 competitively blocked the binding of AM41-type GAS to LDL. Therefore, our findings suggest that LDL may be an opsonin to enhance CD36-dependent opsonic phagocytosis of GAS by monocyte.


Assuntos
Lipoproteínas LDL/metabolismo , Monócitos/imunologia , Monócitos/metabolismo , Proteínas Opsonizantes/metabolismo , Fagocitose/imunologia , Streptococcus pyogenes/imunologia , Anticorpos Monoclonais/farmacologia , Proteínas de Bactérias/farmacologia , Antígenos CD36/antagonistas & inibidores , Linhagem Celular , Células Cultivadas , Colágeno/farmacologia , Humanos , Monócitos/efeitos dos fármacos , Fagocitose/efeitos dos fármacos , Proteínas Recombinantes/farmacologia , Infecções Estreptocócicas/imunologia , Infecções Estreptocócicas/metabolismo , Infecções Estreptocócicas/microbiologia , Células U937
15.
Microbiol Immunol ; 59(7): 419-25, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26094502

RESUMO

We have previously demonstrated that high-density lipoprotein (HDL) can specifically bind to streptococcal collagen-like protein 1 (Scl1) of M41-type group A Streptococcus (GAS). However, the pathological or physiological significance of Scl1-HDL interaction is unknown. Here, the hypothesis that HDL acts as an opsonin to enhance phagocytosis of HDL-bound GAS by monocytes given that some scavenger receptors can mediate the endocytosis of HDL was tested by using FITC-labeled bacteria, human U937 monocytes and HDL for phagocytic assays. HDL (10 µg/mL) was found to significantly enhance internalization of M41-type (ATCC 12373) GAS by U937 cells after 60 min incubation, compared with an HDL-free group. The internalized GAS were dead after 60 min incubation with U937 cells regardless of presence and absence of HDL. Although very-low-density lipoprotein (VLDL) could specifically bind to ATCC 12373 strain, it did not promote phagocytosis of GAS. Additionally, LDL, HDL and VLDL did not enhance phagocytosis of CMCC 32198 strain because this strain did not bind to these lipoproteins. A physiological concentration of HDL (1000 µg/mL) had a similar effect. Anti-CD36 antibody completely abolished opsonic phagocytosis whereas anti-CD4 antibody did not, indicating that CD36 is the major scavenger receptor mediating the uptake of HDL-opsonized GAS by U937 cells. Furthermore, because rScl1 competitively blocked the interaction of ATCC 12373 strain with HDL recombinant Scl1 (rScl1) derived from M41-type GAS, it significantly decreased opsonophagocytosis of ATCC 12373 strain but not of CMCC 32198 strain. Therefore, our findings suggest that HDL may be an opsonin that enhances CD36-dependent opsonophagocytosis of GAS by U937 cells.


Assuntos
Lipoproteínas HDL/imunologia , Proteínas Opsonizantes/imunologia , Fagocitose , Infecções Estreptocócicas/imunologia , Streptococcus pyogenes/imunologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/imunologia , Antígenos CD36/genética , Antígenos CD36/imunologia , Colágeno/genética , Colágeno/imunologia , Humanos , Monócitos/imunologia , Infecções Estreptocócicas/microbiologia , Streptococcus pyogenes/genética , Células U937
16.
Drug Deliv ; 22(1): 111-6, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24735245

RESUMO

CONTEXT: Hen egg low-density lipoprotein (heLDL), which is present in large quantities in egg yolk, share a high identity with human apolipoprotein B-100 precursor. OBJECTIVE: This study investigated the use of heLDL as a macrophage-targeted drug delivery carrier against intracellular Staphylococcus aureus. METHODS: Rifapentine (RPT) was incorporated into heLDL (RPT-heLDL). Staphylococcus aureus ATCC 29740 and human U937 macrophage were used as intracellular infection models. RESULTS AND CONCLUSION: The loading efficiency of RPT into the heLDL was 66.10 ± 2.28 µg RPT/mg heLDL. Fluorescence microscopy and oil red O staining results indicated RPT-heLDL can be taken up by U937 macrophages. The cell viability (MTT assay) was increased when the concentration of heLDL was <150 µg/mL. Unloaded heLDL (100 µg/mL) can inhibit the growth of intracellular S. aureus compared with the untreated control group after 18 h incubation. RPT-heLDL (6.6 µg/mL RPT, 100 µg/mL heLDL) eliminated 94% of intracellular S. aureus, whereas the corresponding dose of free RPT (6.6 µg/mL) induced an 87% reduction. The in vitro results of the current study indicated that heLDL might be used as a suitable drug carrier for targeting human macrophages.


Assuntos
Sistemas de Liberação de Medicamentos , Lipoproteínas/química , Rifampina/análogos & derivados , Staphylococcus aureus/efeitos dos fármacos , Animais , Antibacterianos/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Galinhas , Portadores de Fármacos/química , Proteínas do Ovo/química , Gema de Ovo/química , Humanos , Macrófagos/metabolismo , Microscopia de Fluorescência , Rifampina/administração & dosagem , Rifampina/farmacologia
17.
Wei Sheng Wu Xue Bao ; 50(7): 903-8, 2010 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-20815237

RESUMO

OBJECTIVE: To study the interaction of streptococcal collagen-like protein 1 (Scl1) of M41-type group A streptococcus (GAS) ATCC12373 with low-density lipoprotein (LDL). METHODS: We cloned, expressed and purified the recombinant proteins rScl1 and its V region rScl1-V, designated as C176 and C176V, derived from Scl1. 41 of M41-type GAS. The binding of rScl1 to LDL was detected with affinity chromatography-binding assay, Western blot analysis and enzyme-linked immunosorbent assay (ELISA), and whole cell binding assays were used to detect the interactions of whole GAS cells with LDL. RESULTS: The results demonstrated that C176 and C176V could specifically bind purified LDL, and M41-type GAS cells expressing native Sell could bind LDL whereas M6-type GAS could not. CONCLUSION: The Sell of M41-type GAS specifically binds LDL.


Assuntos
Proteínas de Bactérias/metabolismo , Colágeno/metabolismo , Lipoproteínas LDL/metabolismo , Infecções Estreptocócicas/metabolismo , Streptococcus pyogenes/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Colágeno/genética , Humanos , Dados de Sequência Molecular , Ligação Proteica , Alinhamento de Sequência , Streptococcus pyogenes/química , Streptococcus pyogenes/genética
18.
FEMS Microbiol Lett ; 309(1): 55-61, 2010 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-20528941

RESUMO

Streptococcal collagen-like protein 1 (Scl1) is a virulence factor on the surface of group A Streptococcus (GAS). We have reported previously that several Scl1 proteins derived from various M-type GAS strains, including M41, can bind to low-density lipoprotein, but the Scl1 protein derived from the M6-type GAS strain cannot. Here, we demonstrated that recombinant protein, designated C176, derived from Scl1.41 of the GAS M41-type strain also binds both plasma and purified high-density lipoprotein (HDL). Next, we determined that the intact noncollagenous region of C176 was necessary and sufficient for HDL binding. C176-HDL interaction could be eliminated by the presence of low concentrations of the nonionic detergent, Tween 20, indicating the hydrophobic nature of this interaction. We finally showed that whole GAS cells expressing native Scl1.41 protein absorbed HDL from human plasma in the absence of Tween 20, but M6-type GAS cells did not. Altogether, our results add further evidence to the importance of GAS-lipoprotein binding.


Assuntos
Proteínas de Bactérias/metabolismo , Lipoproteínas HDL/metabolismo , Infecções Estreptocócicas/metabolismo , Streptococcus pyogenes/metabolismo , Proteínas de Bactérias/genética , Humanos , Ligação Proteica , Infecções Estreptocócicas/microbiologia , Streptococcus pyogenes/genética
19.
Microbiol Immunol ; 54(4): 246-53, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20377753

RESUMO

Plasma lipoproteins (VLDL, LDL, Lp[a] and HDL) function primarily in lipid transport among tissues and organs. However, cumulative evidence suggests that lipoproteins may also prevent bacterial, viral and parasitic infections and are therefore a component of innate immunity. Lipoproteins can also detoxify lipopolysaccharide and lipoteichoic acid. Infections can induce oxidation of LDL, and oxLDL in turn plays important anti-infective roles and protects against endotoxin-induced tissue damage. There is also evidence that apo(a) is protective against pathogens. Taken together, the evidence suggests that it might be valuable to introduce the concept that plasma lipoproteins belong in the realm of host immune response.


Assuntos
Imunidade Inata , Lipoproteínas/sangue , Infecções Bacterianas/imunologia , Humanos , Lipoproteínas/imunologia , Doenças Parasitárias/imunologia , Viroses/imunologia
20.
FEMS Microbiol Lett ; 303(1): 61-8, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-20002194

RESUMO

The streptococcal collagen-like protein-1, Scl1, is widely expressed by the well-recognized human pathogen group A Streptococcus (GAS). Screening of human ligands for binding to recombinant Scl1 identified cellular fibronectin and laminin as binding partners. Both ligands interacted with the globular domain of Scl1, which is also able to bind the low-density lipoprotein. Native Scl1 mediated GAS adherence to ligand-coated glass cover slips and promoted GAS internalization into HEp-2 cells. This work identifies new ligands of the Scl1 protein that are known to be important in GAS pathogenesis and suggests a novel ligand-switching mechanism between blood and tissue environments, thereby facilitating host colonization and GAS dissemination.


Assuntos
Adesinas Bacterianas/metabolismo , Aderência Bacteriana , Proteínas de Bactérias/metabolismo , Colágeno/metabolismo , Fibronectinas/metabolismo , Laminina/metabolismo , Streptococcus pyogenes/metabolismo , Streptococcus pyogenes/patogenicidade , Linhagem Celular , Hepatócitos/microbiologia , Humanos , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas
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