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1.
J Dent Res ; 102(11): 1180-1190, 2023 Oct.
Article in English | MEDLINE | ID: mdl-37555431

ABSTRACT

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.


Subject(s)
Anti-Infective Agents , Dental Caries , Humans , Dental Restoration, Permanent , Dental Materials , Composite Resins , Dental Caries/prevention & control , Dentistry
2.
J Dent Res ; 100(10): 1063-1071, 2021 09.
Article in English | MEDLINE | ID: mdl-34167373

ABSTRACT

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.


Subject(s)
Nanocomposites , Aggregatibacter actinomycetemcomitans , Anti-Bacterial Agents , Biofilms , Methacrylates , RNA, Ribosomal, 16S
4.
J Dent Res ; 96(8): 855-863, 2017 Jul.
Article in English | MEDLINE | ID: mdl-28530844

ABSTRACT

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.


Subject(s)
Anti-Infective Agents/pharmacology , Cariostatic Agents/pharmacology , Dental Caries/microbiology , Dental Caries/prevention & control , Resins, Synthetic/pharmacology , Biocompatible Materials/pharmacology , Biofilms/drug effects , Calcium Phosphates/pharmacology , Chlorhexidine/pharmacology , Dental Plaque/microbiology , Dental Plaque/prevention & control , Humans , Methacrylates/pharmacology , Nanoparticles , Quaternary Ammonium Compounds/pharmacology
5.
Am J Transplant ; 17(11): 2851-2862, 2017 Nov.
Article in English | MEDLINE | ID: mdl-28449409

ABSTRACT

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.


Subject(s)
Biomarkers/metabolism , Gene Expression Profiling , Graft Rejection/diagnosis , Kidney Failure, Chronic/surgery , Kidney Transplantation/adverse effects , Adult , Aged , Aged, 80 and over , Biopsy , Female , Follow-Up Studies , Glomerular Filtration Rate , Graft Rejection/etiology , Graft Rejection/metabolism , Graft Survival , Humans , Kidney Function Tests , Male , Middle Aged , Prognosis , Prospective Studies , Risk Factors , Young Adult
6.
Am J Transplant ; 17(8): 2078-2091, 2017 Aug.
Article in English | MEDLINE | ID: mdl-28422412

ABSTRACT

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.


Subject(s)
Graft Rejection/pathology , Kidney Diseases/pathology , Kidney Transplantation/adverse effects , Polyomavirus Infections/pathology , Postoperative Complications , Tumor Virus Infections/pathology , Viremia/pathology , Adult , Aged , Aged, 80 and over , BK Virus/isolation & purification , BK Virus/pathogenicity , Cohort Studies , Female , Follow-Up Studies , Glomerular Filtration Rate , Graft Rejection/etiology , Graft Survival , Humans , Kidney Diseases/etiology , Kidney Function Tests , Male , Middle Aged , Polyomavirus Infections/etiology , Prognosis , Risk Factors , Transplantation, Homologous , Tumor Virus Infections/etiology , Viral Load , Viremia/etiology
7.
Transpl Infect Dis ; 18(3): 423-30, 2016 Jun.
Article in English | MEDLINE | ID: mdl-27016725

ABSTRACT

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.


Subject(s)
Epstein-Barr Virus Infections/immunology , Herpesvirus 4, Human/immunology , Kidney Transplantation/adverse effects , Lymphoproliferative Disorders/etiology , Postoperative Complications/immunology , Adult , Aged , Cohort Studies , Epstein-Barr Virus Infections/virology , Female , Humans , Immunosuppression Therapy , Kidney/immunology , Kidney/surgery , Kidney/virology , Lymphoproliferative Disorders/immunology , Male , Middle Aged , Postoperative Complications/virology , Prospective Studies , Seroconversion , Transplantation, Homologous/adverse effects , Viremia
8.
ACS Macro Lett ; 5(4): 430-434, 2016 Apr 19.
Article in English | MEDLINE | ID: mdl-35607237

ABSTRACT

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.
Article in English | MEDLINE | ID: mdl-25715378

ABSTRACT

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.


Subject(s)
Anti-Bacterial Agents/pharmacology , Biofilms/drug effects , Methacrylates/pharmacology , Quaternary Ammonium Compounds/pharmacology , Resin Cements/chemistry , Streptococcus/drug effects , Anthracenes , Bacterial Load/drug effects , Humans , Hydrogen-Ion Concentration , Lactic Acid/analysis , Materials Testing , Methacrylates/chemistry , Microbial Viability/drug effects , Microscopy, Confocal , Microscopy, Electron, Scanning , Polysaccharides, Bacterial/chemistry , Quaternary Ammonium Compounds/chemistry , Streptococcus gordonii/drug effects , Streptococcus mutans/drug effects , Streptococcus sanguis/drug effects
10.
J Dent Res ; 93(7): 618-25, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24799422

ABSTRACT

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.


Subject(s)
Bone Regeneration/physiology , Calcium Phosphates/chemistry , Dental Cements/chemistry , Stem Cell Transplantation/methods , Tissue Scaffolds/chemistry , Embryonic Stem Cells/transplantation , Humans , Mesenchymal Stem Cell Transplantation/methods , Pluripotent Stem Cells/transplantation , Tissue Engineering/methods
11.
J Dent Res ; 92(10): 932-8, 2013 Oct.
Article in English | MEDLINE | ID: mdl-23958761

ABSTRACT

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.


Subject(s)
Anti-Bacterial Agents/pharmacology , Bacterial Adhesion/drug effects , Dentin-Bonding Agents/pharmacology , Quaternary Ammonium Compounds/chemistry , Resin Cements/pharmacology , Streptococcus mutans/drug effects , Anti-Bacterial Agents/chemistry , Biofilms/drug effects , Cell Survival/drug effects , Colony Count, Microbial , Dentin-Bonding Agents/chemistry , Fibroblasts/drug effects , Materials Testing , Odontoblasts/drug effects , Quaternary Ammonium Compounds/pharmacology , Resin Cements/chemistry
12.
J Hum Hypertens ; 27(7): 445-52, 2013 Jul.
Article in English | MEDLINE | ID: mdl-23254596

ABSTRACT

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.


Subject(s)
Algorithms , Amlodipine/therapeutic use , Angiotensin II Type 1 Receptor Blockers/therapeutic use , Antihypertensive Agents/therapeutic use , Blood Pressure/drug effects , Calcium Channel Blockers/therapeutic use , Diabetes Mellitus, Type 2/complications , Hypertension/drug therapy , Imidazoles/therapeutic use , Tetrazoles/therapeutic use , Adult , Aged , Amlodipine/adverse effects , Angiotensin II Type 1 Receptor Blockers/adverse effects , Antihypertensive Agents/adverse effects , Calcium Channel Blockers/adverse effects , Diabetes Mellitus, Type 2/diagnosis , Drug Combinations , Drug Substitution , Drug Therapy, Combination , Female , Humans , Hydrochlorothiazide/therapeutic use , Hypertension/complications , Hypertension/diagnosis , Hypertension/physiopathology , Imidazoles/adverse effects , Male , Middle Aged , Olmesartan Medoxomil , Prospective Studies , Sodium Chloride Symporter Inhibitors/therapeutic use , Tetrazoles/adverse effects , Time Factors , Treatment Outcome
14.
J Dent Res ; 91(10): 979-84, 2012 Oct.
Article in English | MEDLINE | ID: mdl-22933607

ABSTRACT

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.


Subject(s)
Calcium Phosphates/metabolism , Dental Enamel/metabolism , Nanocomposites/chemistry , Tooth Demineralization/therapy , Tooth Remineralization/methods , Analysis of Variance , Cariostatic Agents , Composite Resins/chemistry , Composite Resins/therapeutic use , Fluorides , Humans , Methacrylates , Microradiography , Nanocomposites/therapeutic use , Phthalic Acids , Polyethylene Glycols , Polymethacrylic Acids , Ytterbium
15.
Acta Biomater ; 8(9): 3436-45, 2012 Sep.
Article in English | MEDLINE | ID: mdl-22633970

ABSTRACT

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.


Subject(s)
Alginates , Bone Cements , Bone and Bones , Calcium Phosphates/chemistry , Embryonic Stem Cells/cytology , Microspheres , Tissue Engineering , Alkaline Phosphatase/genetics , Alkaline Phosphatase/metabolism , Bone and Bones/enzymology , Cells, Cultured , Flow Cytometry , Glucuronic Acid , Hexuronic Acids , Humans
16.
J Dent Res ; 91(6): 598-604, 2012 Jun.
Article in English | MEDLINE | ID: mdl-22492276

ABSTRACT

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.


Subject(s)
Biofilms/drug effects , Composite Resins/chemistry , Dental Bonding , Dentin-Bonding Agents/chemistry , Resin Cements , Analysis of Variance , Colony Count, Microbial , Dental Restoration, Permanent/methods , Dental Stress Analysis , Humans , Materials Testing , Molar, Third , Nanocomposites/chemistry , Quaternary Ammonium Compounds , Shear Strength , Silver , Statistics, Nonparametric , Streptococcus mutans/drug effects
17.
J Dent Res ; 91(5): 460-6, 2012 May.
Article in English | MEDLINE | ID: mdl-22403412

ABSTRACT

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.


Subject(s)
Anti-Bacterial Agents/chemistry , Calcium Phosphates/pharmacology , Cariostatic Agents/chemistry , Composite Resins/chemistry , Dental Restoration, Permanent/methods , Nanocomposites/chemistry , Quaternary Ammonium Compounds/pharmacology , Streptococcus mutans/drug effects , Anti-Bacterial Agents/pharmacology , Biofilms/drug effects , Cariostatic Agents/pharmacology , Colony Count, Microbial , Composite Resins/pharmacology , Dental Caries/prevention & control , Dental Stress Analysis , Elastic Modulus , Lactic Acid/metabolism , Materials Testing , Pliability , Streptococcus mutans/metabolism , Water
18.
Epidemiol Infect ; 140(2): 192-206, 2012 Feb.
Article in English | MEDLINE | ID: mdl-21906415

ABSTRACT

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.


Subject(s)
Anti-Infective Agents/therapeutic use , Bacterial Infections/microbiology , Bacterial Infections/veterinary , Drug Resistance, Bacterial , Fish Diseases/microbiology , Fishes , Zoonoses/microbiology , Animals , Anti-Infective Agents/adverse effects , Aquaculture , Bacterial Infections/drug therapy , Bacterial Infections/transmission , Fish Diseases/drug therapy , Fish Diseases/transmission , Humans , Surveys and Questionnaires , Zoonoses/transmission
19.
Am J Transplant ; 11(9): 1943-50, 2011 Sep.
Article in English | MEDLINE | ID: mdl-21812917

ABSTRACT

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.


Subject(s)
Graft Survival , Kidney Transplantation , Uric Acid/blood , Adult , Aged , Glomerular Filtration Rate , Humans , Male , Middle Aged , Proportional Hazards Models
20.
Biol Cybern ; 105(2): 89-119, 2011 Aug.
Article in English | MEDLINE | ID: mdl-21809130

ABSTRACT

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.


Subject(s)
Biomechanical Phenomena/physiology , Cybernetics , Computer Simulation , Feedback , Goals , Hand , Humans , Models, Biological , Movement/physiology , Task Performance and Analysis
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