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1.
J Sleep Res ; : e14137, 2024 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-38199868

RESUMEN

The association between sleep and pain has been investigated widely. However, inconsistent results from animal studies compared with human data show the need for a validated animal model in the sleep-pain association field. Our study aims to validate common neuropathic pain models as a tool for evaluating the sleep-pain association. Electrodes electroencephalogram (EEG) and electromyogram (EMG) were surgically implanted to measure sleep. The von Frey test was used to measure pain sensitivity. Following the baseline data acquisition, two pain-modelling procedures were performed: sciatic nerve crush injury (SCI) and common peroneal nerve ligation (CPL). Post-injury measurements were performed on days 1, 5, 10, and 15 post-surgery. The results presented decreased paw withdrawal thresholds and reduced NREM sleep duration in both models on the first post-surgery day. In the SCI model, NREM sleep duration was negatively correlated with paw withdrawal thresholds (p = 0.0466), but not in the CPL model. Wake alpha and theta EEG powers were also correlated with the pain threshold. The results confirm that the SCI model shows disturbed sleep patterns associated with increased pain sensitivity, suggesting it is a reliable tool for investigating sleep disturbances associated with neuropathic pain.

2.
BMC Anesthesiol ; 24(1): 203, 2024 Jun 08.
Artículo en Inglés | MEDLINE | ID: mdl-38851689

RESUMEN

BACKGROUND: Ultrasound-guided transversus abdominis plane (TAP) block is commonly used for pain control in laparoscopic cholecystectomy. However, significant pain persists, affecting patient recovery and sleep quality on the day of surgery. We compared the analgesic effect of ultrasound-guided TAP block with or without rectus sheath (RS) block in patients undergoing laparoscopic cholecystectomy using the visual analog scale (VAS) scores. METHODS: The study was registered before patient enrollment at the Clinical Research Information Service (registration number: KCT0006468, 19/08/2021). 88 American Society of Anesthesiologist physical status I-III patients undergoing laparoscopic cholecystectomy were divided into two groups. RS-TAP group received right lateral and right subcostal TAP block, and RS block with 0.2% ropivacaine (30 mL); Bi-TAP group received bilateral and right subcostal TAP block with same amount of ropivacaine. The primary outcome was visual analogue scale (VAS) for 48 h postoperatively. Secondary outcomes included the use of rescue analgesics, cumulative intravenous patient-controlled analgesia (IV-PCA) consumption, patient satisfaction, sleep quality, and incidence of adverse events. RESULTS: There was no significant difference in VAS score between two groups for 48 h postoperatively. We found no difference between the groups in any of the secondary outcomes: the use of rescue analgesics, consumption of IV-PCA, patient satisfaction with postoperative pain control, sleep quality, and the incidence of postoperative adverse events. CONCLUSION: Both RS-TAP and Bi-TAP blocks provided clinically acceptable pain control in patients undergoing laparoscopic cholecystectomy, although there was no significant difference between two combination blocks in postoperative analgesia or sleep quality.


Asunto(s)
Músculos Abdominales , Colecistectomía Laparoscópica , Bloqueo Nervioso , Dolor Postoperatorio , Ropivacaína , Ultrasonografía Intervencional , Humanos , Colecistectomía Laparoscópica/métodos , Femenino , Masculino , Ultrasonografía Intervencional/métodos , Bloqueo Nervioso/métodos , Persona de Mediana Edad , Dolor Postoperatorio/prevención & control , Dolor Postoperatorio/tratamiento farmacológico , Ropivacaína/administración & dosificación , Adulto , Anestésicos Locales/administración & dosificación , Dimensión del Dolor/métodos , Recto del Abdomen/inervación , Recto del Abdomen/diagnóstico por imagen , Satisfacción del Paciente , Analgesia Controlada por el Paciente/métodos , Anciano
3.
Angew Chem Int Ed Engl ; 63(22): e202403886, 2024 May 27.
Artículo en Inglés | MEDLINE | ID: mdl-38545689

RESUMEN

The photocatalytic reduction of carbon dioxide (CO2) represents an attractive approach for solar-energy storage and leads to the production of renewable fuels and valuable chemicals. Although some osmium (Os) photosensitizers absorb long wavelengths in the visible-light region, a self-photosensitized, mononuclear Os catalyst for red-light-driven CO2 reduction has not yet been exploited. Here, we discovered that the introduction of an Os metal to a PNNP-type tetradentate ligand resulted in the absorption of light with longer-wavelength (350-700 nm) and that can be applied to a panchromatic self-photosensitized catalyst for CO2 reduction to give mainly carbon monoxide (CO) with a total turnover number (TON) of 625 under photoirradiation (λ≥400 nm). CO2 photoreduction also proceeded under irradiation with blue (λ0=405 nm), green (λ0=525 nm), or red (λ0=630 nm) light to give CO with >90 % selectivity. The quantum efficiency using red light was determined to be 12 % for the generation of CO. A catalytic mechanism is proposed based on the detection of intermediates using various spectroscopic techniques, including transient absorption, electron paramagnetic resonance, and UV/Vis spectroscopy.

4.
Genomics ; 112(2): 1208-1213, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-31295546

RESUMEN

Interpretation of noncoding disease variants, which comprise the vast majority of Genome-wide association studies (GWAS) hits, remains a momentous challenge due to haplotype structure and our limited understanding of the mechanisms and physiological contexts of noncoding elements. GWAS have identified loci underlying human diseases, but assigning the causal nucleotide changes still remain a controversial issue. Here we addressed these issues through the combination of high-density genotyping and epigenomic data using a random forest model to discover the noncoding causal variants. Focusing on autoimmune diseases, we triaged putative causal variants for atopic dermatitis and inflammatory bowel diseases. Making a filtering pipeline, we found three interesting single nucleotide polymorphisms (rs1800630, rs1799964 and rs4796793) in the upstream site of TNF and STAT3 genes, two frequent genes shared in some autoimmune diseases, and show how those variants affect on TNF and STAT3 expression levels. All data and source codes related to this manuscript are available at https://github.com/jieunjung511/Autoimmune-research.


Asunto(s)
Dermatitis Atópica/genética , Enfermedades Inflamatorias del Intestino/genética , Polimorfismo de Nucleótido Simple , Factor de Transcripción STAT3/genética , Factor de Necrosis Tumoral alfa/genética , Secuencias Reguladoras de Ácidos Nucleicos
5.
J Am Chem Soc ; 142(23): 10261-10266, 2020 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-32456417

RESUMEN

A highly efficient tetradentate PNNP-type Ir photocatalyst, Mes-IrPCY2, was developed for the reduction of carbon dioxide. The photocatalyst furnished formic acid (HCO2H) with 87% selectivity together with carbon monoxide to achieve a turnover number of 2560, which is the highest among CO2 reduction photocatalysts without an additional photosensitizer. Mes-IrPCY2 exhibited outstanding photocatalytic CO2 reduction activity in the presence of the sacrificial electron source 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH) in CO2-saturated N,N-dimethylacetamide under irradiation with visible light. The quantum yield was determined to be 49% for the generation of HCO2H and CO. Electron paramagnetic resonance and UV-vis spectroscopy studies of Mes-IrPCY2 with a sacrificial electron donor revealed that the one-electron-reduced species is the key intermediate for the selective formation of HCO2H.

6.
J Am Chem Soc ; 141(16): 6748-6754, 2019 04 24.
Artículo en Inglés | MEDLINE | ID: mdl-30943724

RESUMEN

Photoirradiation of an acetonitrile solution containing p-benzoquinone derivatives (X-Q) as plastoquinone analogs, a nonheme iron(II) complex, [(N4Py)FeII]2+ (N4Py = N, N-bis(2-pyridylmethyl)- N-bis(2-pyridyl)methylamine), and H2O afforded the evolution of O2 and the formation of the corresponding hydroquinone derivatives (X-QH2) quantitatively. During the photodriven oxidation of water by X-Q, [(N4Py)FeII]2+ was oxidized by the excited state of X-Q to produce the iron(IV)-oxo complex ([(N4Py)FeIV(O)]2+) quantitatively. The concentration of [(N4Py)FeIV(O)]2+ remained virtually the same during the repeated cycles of photodriven oxidation of water by X-Q. [(N4Py)FeIV(O)]2+ was further oxidized by the excited state of X-Q to [(N4Py)FeV(O)]3+; this FeV-oxo species is proposed as an active oxidant that affects the water oxidation. The photocatalytic mechanism of the water oxidation by X-Q with [(N4Py)FeII]2+ was clarified by detecting intermediates using various spectroscopic techniques, such as transient absorption and electron paramagnetic resonance measurements. To the best of our knowledge, the present study reports the first example of a functional model of Photosystem II (PSII) using X-Q as plastoquinone analogs in the photocatalytic oxidation of water.

7.
J Am Chem Soc ; 141(23): 9155-9159, 2019 06 12.
Artículo en Inglés | MEDLINE | ID: mdl-31145595

RESUMEN

Photocatalytic oxygenation of hexamethylbenzene occurs under visible-light irradiation of an O2-saturated acetonitrile solution containing a cobalt porphyrin complex CoII(TPP) (TPP2- = tetraphenylporphyrin dianion), water, and triflic acid (HOTf) via a one-photon-two-electron process, affording pentamethylbenzyl alcohol and hydrogen peroxide as products with a turnover number of >6000; in this reaction, H2O and O2 were used as an oxygen source and a two-electron oxidant, respectively. The photocatalytic mechanism was clarified by means of electron paramagnetic resonance, time-resolved fluorescence, and transient absorption measurements as well as 18O-labeling experiments with H218O and 18O2. To the best of our knowledge, we report the first example of efficient photocatalytic oxygenation of an organic substrate by a metal complex using H2O as an oxygen source and O2 as a two-electron oxidant.

9.
J Am Chem Soc ; 140(27): 8405-8409, 2018 07 11.
Artículo en Inglés | MEDLINE | ID: mdl-29906116

RESUMEN

Photoexcitation of a MnIV-oxo complex binding scandium ions ([(Bn-TPEN)MnIV(O)]2+-(Sc(OTf)3)2) in a solvent mixture of trifluoroethanol and acetonitrile (v/v = 1:1) resulted in formation of the long-lived photoexcited state, which can hydroxylate benzene to phenol. The photohydroxylation of benzene by [(Bn-TPEN)MnIV(O)]2+-(Sc(OTf)3)2 was made possible by electron transfer from benzene to the long-lived 2 E excited state of [(Bn-TPEN)MnIV(O)]2+-(Sc(OTf)3)2 to produce a benzene radical cation, which reacted with water as revealed by laser-induced transient absorption measurements.

10.
PLoS Biol ; 13(5): e1002152, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25992628

RESUMEN

Epidermal growth factor receptor variant III (EGFRvIII) has been associated with glioma stemness, but the direct molecular mechanism linking the two is largely unknown. Here, we show that EGFRvIII induces the expression and secretion of pigment epithelium-derived factor (PEDF) via activation of signal transducer and activator of transcription 3 (STAT3), thereby promoting self-renewal and tumor progression of glioma stem cells (GSCs). Mechanistically, PEDF sustained GSC self-renewal by Notch1 cleavage, and the generated intracellular domain of Notch1 (NICD) induced the expression of Sox2 through interaction with its promoter region. Furthermore, a subpopulation with high levels of PEDF was capable of infiltration along corpus callosum. Inhibition of PEDF diminished GSC self-renewal and increased survival of orthotopic tumor-bearing mice. Together, these data indicate the novel role of PEDF as a key regulator of GSC and suggest clinical implications.


Asunto(s)
Receptores ErbB/metabolismo , Proteínas del Ojo/metabolismo , Glioma/etiología , Células Madre Neoplásicas/metabolismo , Factores de Crecimiento Nervioso/metabolismo , Serpinas/metabolismo , Animales , Comunicación Autocrina , Progresión de la Enfermedad , Femenino , Glioma/metabolismo , Glioma/mortalidad , Células HEK293 , Humanos , Ratones Endogámicos BALB C , Ratones Desnudos , Neoplasias Experimentales/metabolismo , Receptores Notch/metabolismo , Factores de Transcripción SOXB1/metabolismo , Factor de Transcripción STAT3/metabolismo
11.
Biofouling ; 34(1): 53-61, 2018 01.
Artículo en Inglés | MEDLINE | ID: mdl-29199458

RESUMEN

The present study investigated the effect of periodic 1-min fluoride treatments on Streptococcus mutans biofilms and then determined the relationship between anti-biofilm activity, treatment frequency, and fluoride concentration using a linear-fitting procedure. S. mutans biofilms were periodically treated (1-min/treatment) with fluoride during biofilm formation and analyzed using microbiological methods, confocal microscopy, and real-time PCR. The results indicated that reductions in the dry weight and acidogenicity of biofilms due to periodic fluoride treatment occurred in a concentration dependent manner. The reduction in dry weight without affecting bacterial cell viability was observed mainly due to the inhibitory effect of fluoride on gtfB and gtfC gene expression, which suppresses EPS production and avoids reduction of the pH below the critical point on the tooth surface. This study suggests that brief periodic exposure to appropriate fluoride concentrations through mouthwashes and toothpastes may affect the virulence and composition of cariogenic biofilms and subsequently prevent dental caries.


Asunto(s)
Biopelículas/efectos de los fármacos , Cariostáticos/farmacología , Caries Dental/microbiología , Fluoruros/farmacología , Higiene Bucal/métodos , Streptococcus mutans/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Expresión Génica/efectos de los fármacos , Genes Bacterianos , Humanos , Viabilidad Microbiana/efectos de los fármacos , Viabilidad Microbiana/genética , Modelos Biológicos , Streptococcus mutans/genética , Streptococcus mutans/fisiología , Virulencia/efectos de los fármacos , Virulencia/genética
12.
Chemistry ; 23(29): 7125-7131, 2017 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-28345242

RESUMEN

Six-electron oxidation of anthracene to anthraquinone by a nonheme MnIV -oxo complex, [(Bn-TPEN)MnIV (O)]2+ , proceeds through a rate-determining electron transfer from anthracene to [(Bn-TPEN)MnIV (O)]2+ , followed by subsequent fast oxidation reactions to give anthraquinone. The reduced MnII complex ([(Bn-TPEN)MnII ]2+ ) is oxidized by [(Bn-TPEN)MnIV (O)]2+ rapidly to produce the µ-oxo dimer ([(Bn-TPEN)MnIII -O-MnIII (Bn-TPEN)]4+ ). The oxygen atoms of the anthraquinone product were found to derive from the manganese-oxo species by the 18 O-labelling experiments. In the presence of Sc3+ ion, formation of an anthracene radical cation was directly detected in the electron transfer from anthracene to a Sc3+ ion-bound MnIV (O) complex, [(Bn-TPEN)MnIV (O)-(Sc(OTf)3 )2 ]2+ , followed by subsequent further oxidation to yield anthraquinone. When anthracene was replaced by 9,10-dimethylanthracene, electron transfer from 9,10-dimethylanthracene to [(Bn-TPEN)MnIV (O)-(Sc(OTf)3 )2 ]2+ occurred rapidly to produce stable 9,10-dimethylanthracene radical cation. The driving force dependence of the rate constants of electron transfer from the anthracene derivatives to [(Bn-TPEN)MnIV (O)]2+ and [(Bn-TPEN)MnIV (O)-(Sc(OTf)3 )2 ]2+ was well-evaluated in light of the Marcus theory of electron transfer.

13.
Angew Chem Int Ed Engl ; 56(13): 3510-3515, 2017 03 20.
Artículo en Inglés | MEDLINE | ID: mdl-28266771

RESUMEN

Metal-superoxo species are involved in a variety of enzymatic oxidation reactions, and multi-electron oxidation of substrates is frequently observed in those enzymatic reactions. A CrIII -superoxo complex, [CrIII (O2 )(TMC)(Cl)]+ (1; TMC=1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), is described that acts as a novel three-electron oxidant in the oxidation of dihydronicotinamide adenine dinucleotide (NADH) analogues. In the reactions of 1 with NADH analogues, a CrIV -oxo complex, [CrIV (O)(TMC)(Cl)]+ (2), is formed by a heterolytic O-O bond cleavage of a putative CrII -hydroperoxo complex, [CrII (OOH)(TMC)(Cl)], which is generated by hydride transfer from NADH analogues to 1. The comparison of the reactivity of NADH analogues with 1 and p-chloranil (Cl4 Q) indicates that oxidation of NADH analogues by 1 proceeds by proton-coupled electron transfer with a very large tunneling effect (for example, with a kinetic isotope effect of 470 at 233 K), followed by rapid electron transfer.

14.
J Cell Biochem ; 117(5): 1145-57, 2016 May.
Artículo en Inglés | MEDLINE | ID: mdl-26448639

RESUMEN

Mesenchymal stem cells (MSCs) are a powerful source for cell therapy in degenerative diseases. The migration ability of MSCs is an important factor that enhances the therapeutic effect of the cells when they are transplanted into target tissues or organs. Hypoxia and the endothelial barrier, which are representative migration microenvironmental factors, are known to be regulated by the integrin-mediated pathway in several cancers. However, their regulatory mechanisms in MSCs remain unclear. Here, the objectives of the study were to compare the expression of markers related to integrin-mediated signaling in placenta-derived MSCs (PDMSCs) dependent on hypoxia and co-cultured with human umbilical vein endothelial cells (HUVECs) and to evaluate their correlations between migration ability and microenvironmetal factors including hypoxia and endothelial cells. The migration abilities of PDMSCs exposed to hypoxic conditions were significantly increased compared with normal fibroblasts (WI-38) and control (P < 0.05). Interestingly, decreased integrin α4 in PDMSCs under hypoxia induce to increase migration abilities of PDMSCs. Also, Rho family-related markers were significantly increased in PDMSCs under hypoxic conditions compared with normoxia (P < 0.05). Furthermore, the migration ability of PDMSCs was decreased by Rho kinase inhibitor treatment (Y-27632) and co-culturing with HUVECs in an ex vivo system. ROCK activity was increased by inhibiting integrin α4 with HUVECs and hypoxia compared with the absence of HUVECs and under normoxia. The findings suggest microenvironment event by hypoxia and the interaction with endothelial cells may be useful as a regulator of MSC migration and provide insight into the migratory mechanism of MSCs in stem cell-based therapy.


Asunto(s)
Movimiento Celular , Células Endoteliales de la Vena Umbilical Humana/citología , Integrina alfa4/metabolismo , Células Madre Mesenquimatosas/citología , Quinasas Asociadas a rho/metabolismo , Amidas/farmacología , Western Blotting , Hipoxia de la Célula , Línea Celular , Células Cultivadas , Microambiente Celular , Técnicas de Cocultivo , Inhibidores Enzimáticos/farmacología , Femenino , Fibroblastos/citología , Fibroblastos/metabolismo , Expresión Génica , Células Endoteliales de la Vena Umbilical Humana/metabolismo , Humanos , Integrina alfa4/genética , Metaloproteinasa 2 de la Matriz/genética , Metaloproteinasa 2 de la Matriz/metabolismo , Células Madre Mesenquimatosas/metabolismo , Placenta/citología , Embarazo , Piridinas/farmacología , Interferencia de ARN , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transducción de Señal/genética , Quinasas Asociadas a rho/antagonistas & inhibidores , Quinasas Asociadas a rho/genética
15.
Inorg Chem ; 55(7): 3218-28, 2016 Apr 04.
Artículo en Inglés | MEDLINE | ID: mdl-26974004

RESUMEN

UV-vis spectral titrations of a manganese(III) corrolazine complex [Mn(III)(TBP8Cz)] with HOTf in benzonitrile (PhCN) indicate mono- and diprotonation of Mn(III)(TBP8Cz) to give Mn(III)(OTf)(TBP8Cz(H)) and [Mn(III)(OTf)(H2O)(TBP8Cz(H)2)][OTf] with protonation constants of 9.0 × 10(6) and 4.7 × 10(3) M(-1), respectively. The protonated sites of Mn(III)(OTf)(TBP8Cz(H)) and [Mn(III)(OTf)(H2O)(TBP8Cz(H)2)][OTf] were identified by X-ray crystal structures of the mono- and diprotonated complexes. In the presence of HOTf, the monoprotonated manganese(III) corrolazine complex [Mn(III)(OTf)(TBP8Cz(H))] acts as an efficient photocatalytic catalyst for the oxidation of hexamethylbenzene and thioanisole by O2 to the corresponding alcohol and sulfoxide with 563 and 902 TON, respectively. Femtosecond laser flash photolysis measurements of Mn(III)(OTf)(TBP8Cz(H)) and [Mn(III)(OTf)(H2O)(TBP8Cz(H)2)][OTf] in the presence of O2 revealed the formation of a tripquintet excited state, which was rapidly converted to a tripseptet excited state. The tripseptet excited state of Mn(III)(OTf)(TBP8Cz(H)) reacted with O2 with a diffusion-limited rate constant to produce the putative Mn(IV)(O2(•-))(OTf)(TBP8Cz(H)), whereas the tripseptet excited state of [Mn(III)(OTf)(H2O)(TBP8Cz(H)2)][OTf] exhibited no reactivity toward O2. In the presence of HOTf, Mn(V)(O)(TBP8Cz) can oxidize not only HMB but also mesitylene to the corresponding alcohols, accompanied by regeneration of Mn(III)(OTf)(TBP8Cz(H)). This thermal reaction was examined for a kinetic isotope effect, and essentially no KIE (1.1) was observed for the oxidation of mesitylene-d12, suggesting a proton-coupled electron transfer (PCET) mechanism is operative in this case. Thus, the monoprotonated manganese(III) corrolazine complex, Mn(III)(OTf)(TBP8Cz(H)), acts as an efficient photocatalyst for the oxidation of HMB by O2 to the alcohol.


Asunto(s)
Complejos de Coordinación/química , Manganeso/química , Metaloporfirinas/química , Oxidantes Fotoquímicos/química , Oxígeno/química , Derivados del Benceno/química , Catálisis , Cristalografía por Rayos X , Modelos Moleculares , Oxidación-Reducción , Protones , Sulfuros/química
16.
Brain ; 138(Pt 9): 2553-70, 2015 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-26121981

RESUMEN

Upregulation of microRNA-21 (miR-21) is known to be strongly associated with the proliferation, invasion, and radio-resistance of glioma cells. However, the regulatory mechanism that governs the biogenesis of miR-21 in glioma is still unclear. Here, we demonstrate that the DEAD-box RNA helicase, DDX23, promotes miR-21 biogenesis at the post-transcriptional level. The expression of DDX23 was enhanced in glioma tissues compared to normal brain, and expression level of DDX23 was highly associated with poor survival of glioma patients. Specific knockdown of DDX23 expression suppressed glioma cell proliferation and invasion in vitro and in vivo, which is similar to the function of miR-21. We found that DDX23 increased the level of miR-21 by promoting primary-to-precursor processing of miR-21 through an interaction with the Drosha microprocessor. Mutagenesis experiments critically demonstrated that the helicase activity of DDX23 was essential for the processing (cropping) of miR-21, and we further found that ivermectin, a RNA helicase inhibitor, decreased miR-21 levels by potentially inhibiting DDX23 activity and blocked invasion and cell proliferation. Moreover, treatment of ivermectin decreased glioma growth in mouse xenografts. Taken together, these results suggest that DDX23 plays an essential role in glioma progression, and might thus be a potential novel target for the therapeutic treatment of glioma.


Asunto(s)
Neoplasias Encefálicas/metabolismo , ARN Helicasas DEAD-box/metabolismo , Glioma/metabolismo , MicroARNs/biosíntesis , Animales , Antiparasitarios/farmacología , Neoplasias Encefálicas/genética , Línea Celular , Proliferación Celular/efectos de los fármacos , Proliferación Celular/genética , ARN Helicasas DEAD-box/genética , Bases de Datos Factuales/estadística & datos numéricos , Glioma/genética , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Humanos , Inmunoprecipitación , Etiquetado Corte-Fin in Situ , Ivermectina/farmacología , Ratones , MicroARNs/genética , ARN Interferente Pequeño/farmacología , Transducción Genética , Regulación hacia Arriba/efectos de los fármacos , Regulación hacia Arriba/genética , Ensayos Antitumor por Modelo de Xenoinjerto
17.
Eur J Oral Sci ; 124(5): 440-446, 2016 10.
Artículo en Inglés | MEDLINE | ID: mdl-27349190

RESUMEN

The aim of this study was to determine the pattern of the antibacterial activity of chlorhexidine digluconate (CHX) against mature Streptococcus mutans biofilms. Streptococcus mutans biofilms were formed on saliva-coated hydroxyapatite discs and then treated with 0-20% CHX, once, three times, or five times (1 min per treatment) during the period of mature biofilm formation (beyond 46 h). After the treatments, the colony-forming unit (CFU) counts of the treated biofilms were determined. The pH values of the spent culture medium were also determined to investigate the change in pH resulting from the antibacterial activity of CHX. The relationships between the concentration of CHX and the CFU counts and the concentration of CHX and culture medium pH, relative to the number of treatments performed, were evaluated using a sigmoidal curve-fitting procedure. The changes in CFU counts and culture medium pH followed sigmoidal curves and were dependent on the concentration of CHX (R2 = 0.99). The sigmoidal curves were left-shifted with increasing number of treatments. Furthermore, the culture-medium pH of the treated biofilms increased as their CFU counts decreased. The lowest CHX concentration to increase culture-medium pH above the critical pH also decreased as the number of treatments increased. These results may provide fundamental information for selecting the appropriate CHX concentrations to treat S. mutans biofilms.


Asunto(s)
Antibacterianos/farmacología , Clorhexidina/análogos & derivados , Streptococcus mutans/efectos de los fármacos , Biopelículas , Clorhexidina/farmacología , Humanos
18.
Biofouling ; 32(9): 1079-87, 2016 10.
Artículo en Inglés | MEDLINE | ID: mdl-27643392

RESUMEN

Despite the widespread use of fluoride for the prevention of dental caries, few studies have demonstrated the effects of fluoride on the bacterial composition of dental biofilms. This study investigated whether fluoride affects the proportion of Streptococcus mutans and S. oralis in mono- and dual-species biofilm models, via microbiological, biochemical, and confocal fluorescence microscope studies. Fluoride did not affect the bacterial count and bio-volume of S. mutans and S. oralis in mono-species biofilms, except for the 24-h-old S. mutans biofilms. However, fluoride reduced the proportion and bio-volume of S. mutans but did not decrease those of S. oralis during both S. oralis and S. mutans dual-species biofilm formation, which may be related to the decrease in extracellular polysaccharide formation by fluoride. These results suggest that fluoride may prevent the shift in the microbial proportion to cariogenic bacteria in dental biofilms, subsequently inhibiting the cariogenic bacteria dominant biofilm formation.


Asunto(s)
Antibiosis/efectos de los fármacos , Biopelículas/efectos de los fármacos , Fluoruros/farmacología , Streptococcus mutans/efectos de los fármacos , Streptococcus oralis/efectos de los fármacos , Carga Bacteriana/efectos de los fármacos , Caries Dental/microbiología , Relación Dosis-Respuesta a Droga , Humanos , Modelos Biológicos , Streptococcus mutans/crecimiento & desarrollo , Streptococcus mutans/fisiología , Streptococcus oralis/crecimiento & desarrollo , Streptococcus oralis/fisiología
19.
Caries Res ; 50(4): 363-71, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27355469

RESUMEN

Fluoride is commonly used as an ingredient of topical oral hygiene measures. Despite the anti-acidogenic activities of fluoride against cariogenic biofilms, the recovery of the biofilms from fluoride damage is unclear. Herein, we investigated the recovery of acid production in Streptococcus mutans biofilms after short-term or during periodic 1-min fluoride treatments. For this study, 46-hour-old S. mutans biofilms were treated with fluoride (0-2,000 ppm F-) for 1-8 min and then incubated in saliva for 0-100 min. The 74-hour-old biofilms were also periodically treated with the fluoride concentration during biofilm formation (1 min/treatment). Changes in acidogenicity and viability were determined via pH drop and colony-forming unit assays, respectively. In this study, acid production after a 1-min fluoride treatment was recovered as saliva incubation time increased, which followed a linear pattern of concentration dependence (R = 0.99, R2 = 0.98). The recovery pattern was in a biphasic pattern, with an initial rapid rate followed by a second slow recovery. Furthermore, recovery from fluoride damage was retarded in a concentration-dependent manner as treatment time increased. In periodic 1-min fluoride treatments, acid production in the biofilms was not diminished during the non-fluoride treatment period; however, it was reduced in a concentration-dependent manner during the fluoride treatment period. The viability of the biofilm cells did not change, even at high fluoride concentrations. Collectively, our results suggest that brief fluoride treatment does not sustain anti-acidogenic activity against S. mutans in biofilms since the damage is recoverable with time.


Asunto(s)
Biopelículas/efectos de los fármacos , Cariostáticos/farmacología , Caries Dental/microbiología , Fluoruros Tópicos/farmacología , Streptococcus mutans/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Caries Dental/terapia , Humanos , Concentración de Iones de Hidrógeno , Viabilidad Microbiana/efectos de los fármacos , Higiene Bucal , Saliva/microbiología , Factores de Tiempo
20.
Angew Chem Int Ed Engl ; 55(26): 7450-4, 2016 06 20.
Artículo en Inglés | MEDLINE | ID: mdl-27191357

RESUMEN

Hydroxylation of mesitylene by a nonheme manganese(IV)-oxo complex, [(N4Py)Mn(IV) (O)](2+) (1), proceeds via one-step hydrogen-atom transfer (HAT) with a large deuterium kinetic isotope effect (KIE) of 3.2(3) at 293 K. In contrast, the same reaction with a triflic acid-bound manganese(IV)-oxo complex, [(N4Py)Mn(IV) (O)](2+) -(HOTf)2 (2), proceeds via electron transfer (ET) with no KIE at 293 K. Interestingly, when the reaction temperature is lowered to less than 263 K in the reaction of 2, however, the mechanism changes again from ET to HAT with a large KIE of 2.9(3). Such a switchover of the reaction mechanism from ET to HAT is shown to occur by changing only temperature in the boundary region between ET and HAT pathways when the driving force of ET from toluene derivatives to 2 is around -0.5 eV. The present results provide a valuable and general guide to predict a switchover of the reaction mechanism from ET to the others, including HAT.

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