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1.
J Dent Res ; 102(11): 1180-1190, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37555431

RESUMO

Despite its reputation as the most widely used restorative dental material currently, resin-based materials have acknowledged shortcomings. As most systematic survival studies of resin composites and dental adhesives indicate, secondary caries is the foremost reason for resin-based restoration failure and life span reduction. In subjects with high caries risk, the microbial community dominated by acidogenic and acid-tolerant bacteria triggers acid-induced deterioration of the bonding interface and/or bulk material and mineral loss around the restorations. In addition, resin-based materials undergo biodegradation in the oral cavity. As a result, the past decades have seen exponential growth in developing restorative dental materials for antimicrobial applications addressing secondary caries prevention and progression. Currently, the main challenge of bioactive resin development is the identification of efficient and safe anticaries agents that are detrimental free to final material properties and show satisfactory long-term performance and favorable clinical translation. This review centers on the continuous efforts to formulate novel bioactive resins employing 1 or multiple agents to enhance the antibiofilm efficacy or achieve multiple functionalities, such as remineralization and antimicrobial activity antidegradation. We present a comprehensive synthesis of the constraints and challenges encountered in the formulation process, the clinical performance-related prerequisites, the materials' intended applicability, and the current advancements in clinical implementation. Moreover, we identify crucial vulnerabilities that arise during the development of dental materials, including particle aggregation, alterations in color, susceptibility to hydrolysis, and loss of physicomechanical core properties of the targeted materials.


Assuntos
Anti-Infecciosos , Cárie Dentária , Humanos , Restauração Dentária Permanente , Materiais Dentários , Resinas Compostas , Cárie Dentária/prevenção & controle , Odontologia
2.
J Dent Res ; 100(10): 1063-1071, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34167373

RESUMO

Cervical composites treating root carious and noncarious cervical lesions usually extend subgingivally. The subgingival margins of composites present poor plaque control, enhanced biofilm accumulation, and cause gingival irritation. A potential material to restore such lesions should combine agents that interfere with bacterial biofilm development and respond to acidic conditions. Here, we explore the use of new bioresponsive bifunctional dental composites against mature microcosm biofilms derived from subgingival plaque samples. The designed formulations contain 2 bioactive agents: dimethylaminohexadecyl methacrylate (DMAHDM) at 3 to 5 wt.% and 20 wt.% nanosized amorphous calcium phosphate (NACP) in a base resin. Composites with no DMAHDM and NACP were used as controls. The newly formulated 5% DMAHDM-20% NACP composite was analyzed by micro-Raman spectroscopy and transmission electron microscopy. The wettability and surface-free energy were also assessed. The inhibitory effect on the in vitro biofilm growth and the 16S rRNA gene sequencing of survival bacterial colonies derived from the composites were analyzed. Whole-biofilm metabolic activity, polysaccharide production, and live/dead images of the biofilm grown over the composites complement the microbiological assays. Overall, the designed formulations had higher contact angles with water and lower surface-free energy compared to the commercial control. The DMAHDM-NACP composites significantly inhibited the growth of total microorganisms, Porphyromonas gingivalis, Prevotella intermedia/nigrescens, Aggregatibacter actinomycetemcomitans, and Fusobacterium nucleatum by 3 to 5-log (P < 0.001). For the colony isolates from control composites, the composition was typically dominated by the genera Veillonella, Fusobacterium, Streptococcus, Eikenella, and Leptotrichia, while Fusobacterium and Veillonella dominated the 5% DMAHDM-20% NACP composites. The DMAHDM-NACP composites contributed to over 80% of reduction in metabolic and polysaccharide activity. The suppression effect on plaque biofilms suggested that DMAHDM-NACP composites might be used as a bioactive material for cervical restorations. These results may propose an exciting path to prevent biofilm growth and improve dental composite restorations' life span.


Assuntos
Nanocompostos , Aggregatibacter actinomycetemcomitans , Antibacterianos , Biofilmes , Metacrilatos , RNA Ribossômico 16S
4.
J Dent Res ; 96(8): 855-863, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28530844

RESUMO

Dental caries is prevalent, and secondary caries causes restoration failures. This article reviews recent studies on developing a new generation of bioactive resins with anticaries properties. Extensive effects were made to develop new antimicrobial composites, bonding agents, and other resins containing quaternary ammonium methacrylates to suppress plaque buildup and bacterial acid production. The effects of alkyl chain length and charge density and the antimicrobial mechanisms for chlorhexidine, nano-silver, quaternary ammonium methacrylates, and protein-repellent agents were discussed. Synergistic effects of contact-killing and protein-repellent properties were shown to yield the greatest biofilm-inhibition effects. The combination of antimicrobial, protein-repellent, and calcium phosphate nanoparticle remineralization was suggested to provide maximal anticaries effects. In addition, for use orally, cytotoxicity and biocompatibility were important considerations for the new bioactive materials. Furthermore, rather than kill all bacteria, it would be more desirable to modulate the oral biofilm compositions via bioactive resins to suppress cariogenic/pathogenic species and promote benign species. For widespread clinical use of the new antimicrobial and therapeutic materials, whether they would induce bacterial drug resistance needs to be determined, which requires further study. Nonetheless, the new generation of bioactive anticaries resins with therapeutic and biofilm acid-inhibiting properties has the potential to substantially benefit oral health.


Assuntos
Anti-Infecciosos/farmacologia , Cariostáticos/farmacologia , Cárie Dentária/microbiologia , Cárie Dentária/prevenção & controle , Resinas Sintéticas/farmacologia , Materiais Biocompatíveis/farmacologia , Biofilmes/efeitos dos fármacos , Fosfatos de Cálcio/farmacologia , Clorexidina/farmacologia , Placa Dentária/microbiologia , Placa Dentária/prevenção & controle , Humanos , Metacrilatos/farmacologia , Nanopartículas , Compostos de Amônio Quaternário/farmacologia
5.
Am J Transplant ; 17(11): 2851-2862, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28449409

RESUMO

The authors conducted a prospective trial to assess the feasibility of real time central molecular assessment of kidney transplant biopsy samples from 10 North American or European centers. Biopsy samples taken 1 day to 34 years posttransplantation were stabilized in RNAlater, sent via courier overnight at ambient temperature to the central laboratory, and processed (29 h workflow) using microarrays to assess T cell- and antibody-mediated rejection (TCMR and ABMR, respectively). Of 538 biopsy samples submitted, 519 (96%) were sufficient for microarray analysis (average length, 3 mm). Automated reports were generated without knowledge of histology and HLA antibody, with diagnoses assigned based on Molecular Microscope Diagnostic System (MMDx) classifier algorithms and signed out by one observer. Agreement between MMDx and histology (balanced accuracy) was 77% for TCMR, 77% for ABMR, and 76% for no rejection. A classification tree derived to provide automated sign-outs predicted the observer sign-outs with >90% accuracy. In 451 biopsy samples where feedback was obtained, clinicians indicated that MMDx more frequently agreed with clinical judgment (87%) than did histology (80%) (p = 0.0042). In 81% of feedback forms, clinicians reported that MMDx increased confidence in management compared with conventional assessment alone. The authors conclude that real time central molecular assessment is feasible and offers a useful new dimension in biopsy interpretation. ClinicalTrials.gov NCT#01299168.


Assuntos
Biomarcadores/metabolismo , Perfilação da Expressão Gênica , Rejeição de Enxerto/diagnóstico , Falência Renal Crônica/cirurgia , Transplante de Rim/efeitos adversos , Adulto , Idoso , Idoso de 80 Anos ou mais , Biópsia , Feminino , Seguimentos , Taxa de Filtração Glomerular , Rejeição de Enxerto/etiologia , Rejeição de Enxerto/metabolismo , Sobrevivência de Enxerto , Humanos , Testes de Função Renal , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Prospectivos , Fatores de Risco , Adulto Jovem
6.
Am J Transplant ; 17(8): 2078-2091, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28422412

RESUMO

Long-term clinicopathological studies of BK-associated nephropathy (PyVAN) are not available. We studied 206 biopsies (71 patients), followed 3.09 ± 1.46 years after immunosuppression reduction. The biopsy features (% immunostain for PyV large T ag + staining and inflammation ± acute rejection) were correlated with viral load dynamics and serum creatinine to define the clinicopathological status (PyVCPS). Incidence of acute rejection was 28% in the second biopsy and 50% subsequently (25% mixed T cell-mediated allograft rejection (TCMR) + antibody-mediated allograft rejection (AMR); rejection overall affected 38% of patients (>50% AMR). Graft loss was 15.4% (0.8-5.3 years after PyVAN); 76% had complete viral clearance (mean 28 weeks). The only predictors of graft loss were acute rejection (TCMR p = 0.008, any type p = 0.07), and increased "t" and "ci" in the second biopsy (p = 0.006 and 0.048). Higher peak viremia correlated with poorer viral clearance (p = 0.002). Presumptive and proven PyVAN had similar presentation, evolution, and outcome. Late PyVAN (>2 years, 9.8%) justifies BK viremia evaluation at any point with graft dysfunction and/or biopsy evaluation. This study describes the histological evolution of PyVAN and corresponding clinicopathological correlations. Although the pathological features overall reflect the viral and immunological interactions, the PyVAN course remains difficult to predict based on any single feature. Appropriate clinical management requires repeat biopsies and determination of the PyVCPS at relevant time points, for corresponding personalized immunosuppression adjustment.


Assuntos
Rejeição de Enxerto/patologia , Nefropatias/patologia , Transplante de Rim/efeitos adversos , Infecções por Polyomavirus/patologia , Complicações Pós-Operatórias , Infecções Tumorais por Vírus/patologia , Viremia/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Vírus BK/isolamento & purificação , Vírus BK/patogenicidade , Estudos de Coortes , Feminino , Seguimentos , Taxa de Filtração Glomerular , Rejeição de Enxerto/etiologia , Sobrevivência de Enxerto , Humanos , Nefropatias/etiologia , Testes de Função Renal , Masculino , Pessoa de Meia-Idade , Infecções por Polyomavirus/etiologia , Prognóstico , Fatores de Risco , Transplante Homólogo , Infecções Tumorais por Vírus/etiologia , Carga Viral , Viremia/etiologia
7.
Transpl Infect Dis ; 18(3): 423-30, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27016725

RESUMO

BACKGROUND: Epstein-Barr virus (EBV)-seronegative renal transplant recipients are at risk of post-transplant lymphoproliferative disorder (PTLD). We compared primary EBV infection, seroconversion, and PTLD in EBV-seronegative patients who received renal allograft from seropositive or seronegative donors (D+/R- and D-/R-, respectively). METHODS: We prospectively followed 25 D+/R- and 8 D-/R- recipients. We followed patients from January 1999 to June 2009 with clinical visits, monthly EBV polymerase chain reaction tests, and serologic tests for a period of 1 year after kidney transplantation and on an individual basis thereafter. RESULTS: Three patients (9%) developed PTLD including 2 early-onset (<12 months) and 1 late-onset (>12 months) disease. In D+/R- and D-/R- patients, the frequencies of PTLD (8% vs. 12.5%, P = 0.7), EBV seroconversion (64% vs. 50%, P = 0.4), and EBV viremia (40% vs. 25%, P = 0.6) were not significantly different. Clinical, serologic, and virologic surveillance as well as reduction in immunosuppression after evidence of primary EBV infection resulted in a PTLD rate of 9%, despite a seroconversion rate of 60.6%. Rate of graft loss after reduction in immunosuppression was 10% (2 of 20), which was not significantly different from 13 patients without EBV seroconversion (no graft loss, P = 0.5). Rates of viremia, seroconversion, and PTLD in D+/R- and D-/R- patients appear to be similar. CONCLUSIONS: The incidence of PTLD in renal transplants ranges from 0.5% to 2.9%. Our data show a significantly higher rate in EBV-seronegative renal allograft recipients, suggesting the need for close surveillance. Our data also suggest that donors for EBV-seronegative recipients may be accepted irrespective of positive or negative serostatus, with ongoing surveillance important in either circumstance.


Assuntos
Infecções por Vírus Epstein-Barr/imunologia , Herpesvirus Humano 4/imunologia , Transplante de Rim/efeitos adversos , Transtornos Linfoproliferativos/etiologia , Complicações Pós-Operatórias/imunologia , Adulto , Idoso , Estudos de Coortes , Infecções por Vírus Epstein-Barr/virologia , Feminino , Humanos , Terapia de Imunossupressão , Rim/imunologia , Rim/cirurgia , Rim/virologia , Transtornos Linfoproliferativos/imunologia , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/virologia , Estudos Prospectivos , Soroconversão , Transplante Homólogo/efeitos adversos , Viremia
8.
ACS Macro Lett ; 5(4): 430-434, 2016 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-35607237

RESUMO

We study the conformations of polymer chains in polymer-graphene oxide nanocomposites. We show that the chains have a reduced radius of gyration that is consistent with confinement at a solid interface in the melt, as is expected for well-dispersed, high aspect ratio nanoparticles that are much larger than the polymer coil size. We show that confinement of the polymer chains causes a corresponding reduction in interchain entanglements, and we calculate a contribution to the plateau modulus from the distorted polymer network via a simple scaling argument. Our results are a significant step forward in understanding how two-dimensional nanoparticles affect global material properties at low loadings.

9.
J Dent Res ; 94(4): 622-9, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25715378

RESUMO

Antibacterial adhesives have favorable prospects to inhibit biofilms and secondary caries. The objectives of this study were to investigate the antibacterial effect of dental adhesives containing dimethylaminododecyl methacrylate (DMADDM) on different bacteria in controlled multispecies biofilms and its regulating effect on development of biofilm for the first time. Antibacterial material was synthesized, and Streptococcus mutans, Streptococcus gordonii, and Streptococcus sanguinis were chosen to form multispecies biofilms. Lactic acid assay and pH measurement were conducted to study the acid production of controlled multispecies biofilms. Anthrone method and exopolysaccharide (EPS):bacteria volume ratio measured by confocal laser scanning microscopy were performed to determine the EPS production of biofilms. The colony-forming unit counts, scanning electron microscope imaging, and dead:live volume ratio decided by confocal laser scanning microscopy were used to study the biomass change of controlled multispecies biofilms. The TaqMan real-time polymerase chain reaction and fluorescent in situ hybridization imaging were used to study the proportion change in multispecies biofilms of different groups. The results showed that DMADDM-containing adhesive groups slowed the pH drop and decreased the lactic acid production noticeably, especially lactic acid production in the 5% DMADDM group, which decreased 10- to 30-fold compared with control group (P < 0.05). EPS was reduced significantly in 5% DMADDM group (P < 0.05). The DMADDM groups reduced the colony-forming unit counts significantly (P < 0.05) and had higher dead:live volume ratio in biofilms compared with control group (P < 0.05). The proportion of S. mutans decreased steadily in DMADDM-containing groups and continually increased in control group, and the biofilm had a more healthy development tendency after the regulation of DMADDM. In conclusion, the adhesives containing DMADDM had remarkable antimicrobial properties to serve as "bioactive" adhesive materials and revealed its potential value for antibiofilm and anticaries clinical applications.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Metacrilatos/farmacologia , Compostos de Amônio Quaternário/farmacologia , Cimentos de Resina/química , Streptococcus/efeitos dos fármacos , Antracenos , Carga Bacteriana/efeitos dos fármacos , Humanos , Concentração de Íons de Hidrogênio , Ácido Láctico/análise , Teste de Materiais , Metacrilatos/química , Viabilidade Microbiana/efeitos dos fármacos , Microscopia Confocal , Microscopia Eletrônica de Varredura , Polissacarídeos Bacterianos/química , Compostos de Amônio Quaternário/química , Streptococcus gordonii/efeitos dos fármacos , Streptococcus mutans/efeitos dos fármacos , Streptococcus sanguis/efeitos dos fármacos
10.
J Dent Res ; 93(7): 618-25, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24799422

RESUMO

Calcium phosphate cements (CPCs) have excellent biocompatibility and osteoconductivity for dental, craniofacial, and orthopedic applications. This article reviews recent developments in stem cell delivery via CPC for bone regeneration. This includes: (1) biofunctionalization of the CPC scaffold, (2) co-culturing of osteoblasts/endothelial cells and prevascularization of CPC, (3) seeding of CPC with different stem cell species, (4) human umbilical cord mesenchymal stem cell (hUCMSC) and bone marrow MSC (hBMSC) seeding on CPC for bone regeneration, and (5) human embryonic stem cell (hESC) and induced pluripotent stem cell (hiPSC) seeding with CPC for bone regeneration. Cells exhibited good attachment/proliferation in CPC scaffolds. Stem-cell-CPC constructs generated more new bone and blood vessels in vivo than did the CPC control without cells. hUCMSCs, hESC-MSCs, and hiPSC-MSCs in CPC generated new bone and blood vessels similar to those of hBMSCs; hence, they were viable cell sources for bone engineering. CPC with hESC-MSCs and hiPSC-MSCs generated new bone two- to three-fold that of the CPC control. Therefore, this article demonstrates that: (1) CPC scaffolds are suitable for delivering cells; (2) hUCMSCs, hESCs, and hiPSCs are promising alternatives to hBMSCs, which require invasive procedures to harvest with limited cell quantity; and (3) stem-cell-CPC constructs are highly promising for bone regeneration in dental, craniofacial, and orthopedic applications.


Assuntos
Regeneração Óssea/fisiologia , Fosfatos de Cálcio/química , Cimentos Dentários/química , Transplante de Células-Tronco/métodos , Alicerces Teciduais/química , Células-Tronco Embrionárias/transplante , Humanos , Transplante de Células-Tronco Mesenquimais/métodos , Células-Tronco Pluripotentes/transplante , Engenharia Tecidual/métodos
11.
J Dent Res ; 92(10): 932-8, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23958761

RESUMO

The objectives of this study were to synthesize new quaternary ammonium methacrylates (QAMs) with systematically varied alkyl chain lengths (CL) and to investigate, for the first time, the CL effects on antibacterial efficacy, cytotoxicity, and dentin bond strength of bonding agents. QAMs were synthesized with CL of 3 to 18 and incorporated into Scotchbond Multi-Purpose (SBMP) bonding agent. The cured resins were inoculated with Streptococcus mutans. Bacterial early attachment was investigated at 4 hrs. Biofilm colony-forming units (CFU) were measured after 2 days. With CL increasing from 3 to 16, the minimum inhibitory concentration and minimum bactericidal concentration were decreased by 5 orders of magnitude. Incorporating QAMs into SBMP reduced bacterial early attachment, with the least colonization at CL = 16. Biofilm CFU for CL = 16 was 4 log lower than SBMP control (p < .05). All groups had similar dentin bond strengths (p > .1). The new antibacterial materials had fibroblast/odontoblast viability similar to that of commercial controls. In conclusion, increasing the chain length of new QAMs in bonding agents greatly increased the antibacterial efficacy. A reduction in Streptococcus mutans biofilm CFU by 4 log could be achieved, without compromising bond strength and cytotoxicity. New QAM-containing bonding agents are promising for a wide range of restorations to inhibit biofilms.


Assuntos
Antibacterianos/farmacologia , Aderência Bacteriana/efeitos dos fármacos , Adesivos Dentinários/farmacologia , Compostos de Amônio Quaternário/química , Cimentos de Resina/farmacologia , Streptococcus mutans/efeitos dos fármacos , Antibacterianos/química , Biofilmes/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Contagem de Colônia Microbiana , Adesivos Dentinários/química , Fibroblastos/efeitos dos fármacos , Teste de Materiais , Odontoblastos/efeitos dos fármacos , Compostos de Amônio Quaternário/farmacologia , Cimentos de Resina/química
12.
J Hum Hypertens ; 27(7): 445-52, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23254596

RESUMO

A prespecified subgroup analysis of an open-label, multicenter, single-arm, dose-titration study is presented. The efficacy and safety of 20-week treatment with an amlodipine (AML)/olmesartan medoxomil (OM)±hydrochlorothiazide (HCTZ) algorithm were assessed in patients with hypertension and type 2 diabetes mellitus (T2DM) who were uncontrolled by antihypertensive monotherapy. Eligible patients received AML/OM 5/20 mg for 4 weeks, followed by stepwise uptitration to AML/OM 5/40 mg, AML/OM 10/40 mg, AML/OM 10/40 mg+HCTZ 12.5 mg and AML/OM 10/40 mg+HCTZ 25 mg at 4-week intervals if blood pressure (BP) remained uncontrolled. The primary end point was the achievement of the seated cuff systolic BP (SeSBP) goal (<140 mm Hg, or <130 mm Hg for patients with T2DM) at week 12. Seated cuff BP was significantly reduced from baseline at all titration dose periods. At week 12, the cumulative SeSBP goal was achieved by 57.9% and 80.1% of patients in the T2DM and non-T2DM subgroups, respectively. Treatment was well tolerated, with low rates of peripheral edema. In summary, switching to a treatment algorithm based on AML/OM±HCTZ after failed monotherapy was safe and improved BP control in patients with hypertension and T2DM.


Assuntos
Algoritmos , Anlodipino/uso terapêutico , Bloqueadores do Receptor Tipo 1 de Angiotensina II/uso terapêutico , Anti-Hipertensivos/uso terapêutico , Pressão Sanguínea/efeitos dos fármacos , Bloqueadores dos Canais de Cálcio/uso terapêutico , Diabetes Mellitus Tipo 2/complicações , Hipertensão/tratamento farmacológico , Imidazóis/uso terapêutico , Tetrazóis/uso terapêutico , Adulto , Idoso , Anlodipino/efeitos adversos , Bloqueadores do Receptor Tipo 1 de Angiotensina II/efeitos adversos , Anti-Hipertensivos/efeitos adversos , Bloqueadores dos Canais de Cálcio/efeitos adversos , Diabetes Mellitus Tipo 2/diagnóstico , Combinação de Medicamentos , Substituição de Medicamentos , Quimioterapia Combinada , Feminino , Humanos , Hidroclorotiazida/uso terapêutico , Hipertensão/complicações , Hipertensão/diagnóstico , Hipertensão/fisiopatologia , Imidazóis/efeitos adversos , Masculino , Pessoa de Meia-Idade , Olmesartana Medoxomila , Estudos Prospectivos , Inibidores de Simportadores de Cloreto de Sódio/uso terapêutico , Tetrazóis/efeitos adversos , Fatores de Tempo , Resultado do Tratamento
14.
J Dent Res ; 91(10): 979-84, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22933607

RESUMO

Secondary caries remains the main problem limiting the longevity of composite restorations. The objective of this study was to investigate the remineralization of demineralized human enamel in vitro via a nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP). NACP were synthesized by a spray-drying technique and incorporated into a dental resin. First, caries-like subsurface enamel lesions were created via an acidic solution. Then, NACP nanocomposite or a commercial fluoride-releasing control composite was placed on the demineralized enamel, along with control enamel without a composite. These specimens were then treated with a cyclic demineralization/remineralization regimen for 30 days. Quantitative microradiography showed typical enamel subsurface demineralization before cyclic demineralization/remineralization treatment, and significant remineralization in enamel under the NACP nanocomposite after the demineralization/remineralization treatment. The NACP nanocomposite had the highest enamel remineralization (mean ± SD; n = 6) of 21.8 ± 3.7%, significantly higher than the 5.7 ± 6.9% for fluoride-releasing composite (p < 0.05). The enamel group without composite had further demineralization of -26.1 ± 16.2%. In conclusion, a novel NACP nanocomposite was effective in remineralizing enamel lesions in vitro. Its enamel remineralization was 4-fold that of a fluoride-releasing composite control. Combined with the good mechanical and acid-neutralization properties reported earlier, the new NACP nanocomposite is promising for remineralization of demineralized tooth structures.


Assuntos
Fosfatos de Cálcio/metabolismo , Esmalte Dentário/metabolismo , Nanocompostos/química , Desmineralização do Dente/terapia , Remineralização Dentária/métodos , Análise de Variância , Cariostáticos , Resinas Compostas/química , Resinas Compostas/uso terapêutico , Fluoretos , Humanos , Metacrilatos , Microrradiografia , Nanocompostos/uso terapêutico , Ácidos Ftálicos , Polietilenoglicóis , Ácidos Polimetacrílicos , Itérbio
15.
Acta Biomater ; 8(9): 3436-45, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22633970

RESUMO

Human embryonic stem cells (hESC) are promising for use in regenerative medicine applications because of their strong proliferative ability and multilineage differentiation capability. To date there have been no reports on hESC seeding with calcium phosphate cement (CPC). The objective of this study was to investigate hESC-derived mesenchymal stem cell (hESCd-MSC) encapsulation in hydrogel microbeads in macroporous CPC for bone tissue engineering. hESC were cultured to form embryoid bodies (EB), and the MSC were then migrated out of the EB. hESCd-MSC had surface markers characteristic of MSC, with positive alkaline phosphatase (ALP) staining when cultured in osteogenic medium. hESCd-MSC were encapsulated in alginate at a density of 1millioncellsml(-1), with an average microbead size of 207µm. CPC contained mannitol porogen to create a porosity of 64% and 218-µm macropores, with 20% absorbable fibers for additional porosity when the fibers degrade. hESCd-MSC encapsulated in microbeads in CPC had good viability from 1 to 21days. ALP gene expression at 21days was 25-fold that at 1day. Osteocalcin (OC) at 21days was two orders of magnitude of that at 1day. ALP activity in colorimetric p-nitrophenyl phosphate assay at 21days was fivefold that at 1day. Mineral synthesis by the encapsulated hESCd-MSC at 21days was sevenfold that at 1day. Potential benefits of the CPC-stem cell paste include injectability, intimate adaptation to complex-shaped bone defects, ease in contouring to achieve esthetics in maxillofacial repairs, and in situ setting ability. In conclusion, hESCd-MSC were encapsulated in alginate microbeads in macroporous CPC, showing good cell viability, osteogenic differentiation and mineral synthesis for the first time. The hESCd-MSC-encapsulating macroporous CPC construct is promising for bone regeneration in a wide range of orthopedic and maxillofacial applications.


Assuntos
Alginatos , Cimentos Ósseos , Osso e Ossos , Fosfatos de Cálcio/química , Células-Tronco Embrionárias/citologia , Microesferas , Engenharia Tecidual , Fosfatase Alcalina/genética , Fosfatase Alcalina/metabolismo , Osso e Ossos/enzimologia , Células Cultivadas , Citometria de Fluxo , Ácido Glucurônico , Ácidos Hexurônicos , Humanos
16.
J Dent Res ; 91(6): 598-604, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22492276

RESUMO

Antibacterial bonding agents could combat recurrent caries at the tooth-composite margins. The objectives of this study were to develop novel antibacterial dentin primers containing quaternary ammonium dimethacrylate (QADM) and nanoparticles of silver (NAg), and to investigate the effects on dentin bond strength and dental plaque microcosm biofilms for the first time. Scotchbond Multi-Purpose ("SBMP") bonding agent was used. QADM and NAg were incorporated into SBMP primer, yielding 4 primers: SBMP primer (control), control + 10% QADM (mass), control + 0.05% NAg, and control + 10% QADM + 0.05% NAg. Human saliva was collected to grow microcosm biofilms. The NAg particle size (mean ± SD; n = 100) was 2.7 ± 0.6 nm. Dentin shear bond strengths (n = 10) with human third molars were approximately 30 MPa for all groups (p > 0.1). QADM-NAg-containing primer increased the bacteria inhibition zone by 9-fold, compared with control primer (p < 0.05). QADM-NAg-containing primer reduced lactic acid production and colony-forming units of total micro-organisms, total streptococci, and mutans streptococci by an order of magnitude. In conclusion, novel QADM-NAg-containing primers were strongly antibacterial without compromising dentin bond strength, and hence are promising to inhibit biofilms and secondary caries. The processing method of incorporating QADM and NAg together into the same primer produced the strongest antibacterial effect, which could have a wide applicability to other bonding systems.


Assuntos
Biofilmes/efeitos dos fármacos , Resinas Compostas/química , Colagem Dentária , Adesivos Dentinários/química , Cimentos de Resina , Análise de Variância , Contagem de Colônia Microbiana , Restauração Dentária Permanente/métodos , Análise do Estresse Dentário , Humanos , Teste de Materiais , Dente Serotino , Nanocompostos/química , Compostos de Amônio Quaternário , Resistência ao Cisalhamento , Prata , Estatísticas não Paramétricas , Streptococcus mutans/efeitos dos fármacos
17.
J Dent Res ; 91(5): 460-6, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22403412

RESUMO

Secondary caries is a frequent reason for restoration failure, resulting from acidogenic bacteria and their biofilms. The objectives of this study were to: (1) develop a novel nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP) and quaternary ammonium dimethacrylate (QADM); and (2) investigate its mechanical and antibacterial durability. A spray-drying technique yielded NACP with particle size of 116 nm. The nanocomposite contained NACP and reinforcement glass fillers, with QADM in the resin. Two commercial composites were tested as controls. Composites were inoculated with Streptococcus mutans. After 180-day water-aging, NACP+QADM nanocomposite had flexural strength and elastic modulus matching those of commercial controls (p > 0.1). NACP+QADM nanocomposite reduced the biofilm colony-forming units (CFU) by 3-fold, compared with commercial composites (p < 0.05). Metabolic activity and lactic acid production of biofilms on NACP+QADM were much less than those on commercial composites (p < 0.05). The antibacterial properties of NACP+QADM were maintained after water-aging for 30, 90, and 180 d (p > 0.05). In conclusion, the novel NACP-QADM nanocomposite greatly decreased biofilm metabolic activity, CFU, and lactic acid, while matching the load-bearing capability of commercial composites without antibacterial properties. The NACP-QADM nanocomposite with strong and durable antibacterial properties, together with its previously reported Ca-PO(4) release capability, may render it useful for caries-inhibiting restorations.


Assuntos
Antibacterianos/química , Fosfatos de Cálcio/farmacologia , Cariostáticos/química , Resinas Compostas/química , Restauração Dentária Permanente/métodos , Nanocompostos/química , Compostos de Amônio Quaternário/farmacologia , Streptococcus mutans/efeitos dos fármacos , Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Cariostáticos/farmacologia , Contagem de Colônia Microbiana , Resinas Compostas/farmacologia , Cárie Dentária/prevenção & controle , Análise do Estresse Dentário , Módulo de Elasticidade , Ácido Láctico/metabolismo , Teste de Materiais , Maleabilidade , Streptococcus mutans/metabolismo , Água
18.
Epidemiol Infect ; 140(2): 192-206, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21906415

RESUMO

Using systematic review methodology, global research reporting the frequency of zoonotic bacterial pathogens, antimicrobial use (AMU) and antimicrobial resistance (AMR) in ornamental fish, and human illness due to exposure to ornamental fish, was examined. A survey was performed to elicit opinions of aquaculture-allied personnel on the frequency of AMU and AMR in ornamental fish. The most commonly reported sporadic human infections were associated with Mycobacterium marinum, while Salmonella Paratyphi B var. Java was implicated in all reported outbreaks. Aeromonas spp. were most frequently investigated (n=10 studies) in 25 studies surveying ornamental fish from various sources. High levels of resistance were reported to amoxicillin, penicillin, tetracycline and oxytetracycline, which was also in agreement with the survey respondents' views. Studies on AMU were not found in our review. Survey respondents reported frequent use of quinolones, followed by tetracyclines, nitrofurans, and aminoglycosides. Recommendations for future surveillance and public education efforts are presented.


Assuntos
Anti-Infecciosos/uso terapêutico , Infecções Bacterianas/microbiologia , Infecções Bacterianas/veterinária , Farmacorresistência Bacteriana , Doenças dos Peixes/microbiologia , Peixes , Zoonoses/microbiologia , Animais , Anti-Infecciosos/efeitos adversos , Aquicultura , Infecções Bacterianas/tratamento farmacológico , Infecções Bacterianas/transmissão , Doenças dos Peixes/tratamento farmacológico , Doenças dos Peixes/transmissão , Humanos , Inquéritos e Questionários , Zoonoses/transmissão
19.
Am J Transplant ; 11(9): 1943-50, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21812917

RESUMO

The association of serum uric acid (UA) with kidney transplant outcomes is uncertain. We examined the predictive value of UA during the first year posttransplant as a time-varying factor for graft survival after adjustment for time-dependent and independent confounding factors. Four hundred and eighty-eight renal allograft recipients transplanted from January 2004 to June 2006 and followed for 41.1 ± 17.7 months were included. Data on UA, estimated glomerular filtration rate (eGFR), tacrolimus level, mycophenolate mofetil (MMF) and prednisone doses, use of allopurinol, angiotensin-converting enzyme-inhibitor/angiotensin-receptor-blocker (ACEi/ARB) and diuretics at 1, 3, 6, 9 and 12 months were collected. Primary endpoint of the study was graft loss, defined as graft failure and death. Cox proportional hazard models and generalized estimating equations were used for analysis. UA level was associated with eGFR, gender, retransplantation, decease-donor organ, delayed graft function, diuretics, ACEi/ARB and MMF dose. After adjustment for these confounders, UA was independently associated with increased risk of graft loss (HR: 1.15, p = 0.003; 95% CI: 1.05-1.27). Interestingly, UA interacted with eGFR (HR: 0.996, p < 0.05; 95% CI: 0.993-0.999 for interaction term). Here, we report a significant association between serum UA during first year posttransplant and graft loss, after adjustment for corresponding values of time-varying variables including eGFR, immunosuppressive drug regimen and other confounding factors. Its negative impact seems to be worse with lower eGFR.


Assuntos
Sobrevivência de Enxerto , Transplante de Rim , Ácido Úrico/sangue , Adulto , Idoso , Taxa de Filtração Glomerular , Humanos , Masculino , Pessoa de Meia-Idade , Modelos de Riscos Proporcionais
20.
Biol Cybern ; 105(2): 89-119, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21809130

RESUMO

How do biological agents plan and organise a smooth accurate path to shift from one smooth mode of behaviour to another as part of graceful movement that is both plastic and controlled? This paper addresses the question in conducting a novel shape analysis of approach and adjustment phases in rapid voluntary target aiming and 2-D reaching hand actions. A number of mode changing experiments are reported that investigate these actions under a range of goals and conditions. After a typically roughly aimed approach, regular projective adjustment is observed that has height and velocity kinematic profiles that are scaled copies of one another. This empirical property is encapsulated as a novel self-similar shift function. The mathematics shows that the biological shifts consist of continual deviation from their full Taylor series everywhere throughout their interval, which is a deep form of plasticity not described before. The experimental results find the same approach and adjustment strategy to occur with behavioural trajectories over the full and varied range of tested goals and conditions. The trajectory shapes have a large degree of predictability through using the shift function to handle extensive variation in the trajectories' adjustment across individual behaviours and subjects. We provide connections between the behavioural features and results and various neural studies to show how the methodology may be exploited. The conclusion is that a roughly aimed approach followed by a specific highly plastic shift adjustment can provide a regular basis for fast and accurate goal-directed motion in a simple and generalisable way.


Assuntos
Fenômenos Biomecânicos/fisiologia , Cibernética , Simulação por Computador , Retroalimentação , Objetivos , Mãos , Humanos , Modelos Biológicos , Movimento/fisiologia , Análise e Desempenho de Tarefas
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