RESUMEN
OBJECTIVES: Type 2 diabetes mellitus (DM) has a deleterious effect on dental implant integration into alveolar bone, thought to arise from impaired osteoblast function and consequent reduced bone turnover. However, whether controlling blood glucose with antidiabetic drugs is sufficient to improve implant integration is unclear. This study was designed to evaluate implant integration using diabetic rats with/without an antidiabetic drug. MATERIALS AND METHODS: Titanium screws were surgically implanted in each tibia of 20 Goto-Kakizaki (GK) rats and 5 nondiabetic control rats. After 3 or 9 weeks, osseointegration was determined by testing the removal torque required to displace the screw and by histological analysis of various parameters of bone formation. RESULTS: Removal torque was significantly higher in the nondiabetic control group than in GK rats, irrespective of whether the GK rats had received voglibose. Histology revealed that single-labeled surface area was still high in the GK rats at 9 weeks but had peaked and diminished in control rats. Bone-implant contact area was reduced in GK rats. CONCLUSIONS: Despite controlling blood glucose, voglibose was unable to reverse the bone metabolic effects of DM.
Asunto(s)
Implantes Dentales/efectos adversos , Diabetes Mellitus Tipo 2/complicaciones , Hipoglucemiantes/farmacología , Inositol/análogos & derivados , Osteogénesis/efectos de los fármacos , Proceso Alveolar/efectos de los fármacos , Proceso Alveolar/patología , Proceso Alveolar/fisiología , Animales , Fenómenos Biomecánicos , Análisis del Estrés Dental , Modelos Animales de Enfermedad , Inositol/farmacología , Masculino , Ratones Endogámicos , Osteogénesis/fisiología , Ratas , Ratas WistarRESUMEN
Osteoblasts, originating from mesenchymal stem cells, play a pivotal role in bone formation and mineralization. Several transcription factors including runt-related transcription factor 2 (Runx2) have been reported to be essential for osteoblast differentiation, whereas the cytoplasmic signal transduction pathways controlling the differentiation process have not been fully elucidated. AMP-activated protein kinase (AMPK) is a serine-threonine kinase generally regarded as a key regulator of cellular energy homeostasis, polarity, and division. Recent lines of evidence have indicated that the activity of the catalytic alpha subunit of AMPK is regulated through its phosphorylation by upstream AMPK kinases (AMPKKs) including LKB1. Here, we explored the role of AMPK in osteoblast differentiation using in vitro culture models. Phosphorylation of AMPKalpha was significantly decreased during osteoblastic differentiation in both primary osteoblasts and MC3T3-E1, a mouse osteoblastic cell line. Conversely, the terminal differentiation of primary osteoblasts and MC3T3-E1 cells, represented by matrix mineralization, was significantly inhibited by glucose restriction and stimulation with metformin, both of which are known activators of AMPK. Matrix mineralization of MC3T3-E1 cells was also inhibited by the forced expression of a constitutively active form of AMPKalpha. Metformin significantly inhibited gene expression of Runx2 along with osteoblast differentiation markers including osteocalcin (Ocn), bone sialo protein (Bsp), and osteopontin (Opn). Thus, our present data indicate that differentiation of osteoblasts is functionally associated with decreased AMPK activity.
Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Diferenciación Celular/fisiología , Osteoblastos/citología , Células 3T3-L1 , Proteínas Quinasas Activadas por AMP/genética , Adipocitos/citología , Fosfatasa Alcalina/metabolismo , Aminoimidazol Carboxamida/análogos & derivados , Aminoimidazol Carboxamida/farmacología , Animales , Calcificación Fisiológica/efectos de los fármacos , Diferenciación Celular/efectos de los fármacos , Línea Celular , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Subunidad alfa 1 del Factor de Unión al Sitio Principal/genética , Expresión Génica/efectos de los fármacos , Expresión Génica/genética , Glucosa/deficiencia , Glucosa/farmacología , Hipoglucemiantes/farmacología , Sialoproteína de Unión a Integrina , Metformina/farmacología , Ratones , Ratones Endogámicos C57BL , Osteoblastos/metabolismo , Osteocalcina/genética , Osteopontina/genética , Fosforilación/efectos de los fármacos , Ribonucleótidos/farmacología , Sialoglicoproteínas/genética , TransfecciónRESUMEN
Tooth loss accompanied by a massive defect of the alveolar bone can cause serious problems such as food deposit and esthetic impairment. This report describes procedures for the fabrication of an osseous defect obturator prosthesis connected to a fixed partial denture by a magnetic attachment along with the clinical outcome.
Asunto(s)
Diseño de Dentadura , Dentadura Parcial Fija , Magnetismo/instrumentación , Prótesis Periodontal , Resinas Acrílicas , Proceso Alveolar/patología , Diente Canino/cirugía , Materiales Dentales , Estudios de Seguimiento , Humanos , Masculino , Enfermedades Maxilares/cirugía , Persona de Mediana Edad , Quiste Radicular/cirugía , Propiedades de Superficie , Extracción Dental , Alveolo Dental/patología , Resultado del TratamientoRESUMEN
OBJECTIVE: Limitin is a new member of type I interferon (IFN) identified with an expression cloning based on the growth suppression of a myelomonocytic leukemia cell line WEHI3. Although limitin uses the IFN-alpha/beta receptor, its signal transduction pathways to express the antiviral effects are different from those of IFN-alpha. To clarify the characteristics of limitin, we compared the biological activities of limitin, such as the antiviral, immunomodulatory, antitumor, and myelosuppressive effects, with IFN-alpha. MATERIALS AND METHODS: Limitin and IFN-alpha were titered with a cytopathic effect dye binding assay. Induction of MHC class I on a keratinocyte cell line PAM212 was estimated with flow cytometry. Induction of OVA-restricted cytotoxic T lymphocyte (CTL) activity was analyzed with 51Cr release assay. Antiproliferative effects were evaluated with 3H-thymidine incorporation assay using WEHI3 and a lymphoblast cell line L1210. Myelosuppresive effects were evaluated with colony assay. In vivo side effects were estimated after the injection of limitin or IFN-alpha. RESULTS: Limitin had relatively higher antiviral activity than IFN-alpha. Limitin induced the surface expression of MHC class I, the enhancement of CTL activity, and the growth inhibition of lymphohematopoietic cell lines as strong as IFN-alpha. Nevertheless, the treatment of mice with limitin showed neither myelosuppression nor fever that are common adverse effects of IFN-alpha. CONCLUSIONS: Strong immunomodulatory, antitumor, and antiviral effects with weak myelosuppressive and weak acute toxic effects of limitin indicate that it may be useful as a new therapeutic drug for virus-hepatitis and cancers.
Asunto(s)
Adyuvantes Inmunológicos/farmacología , Antineoplásicos/farmacología , Médula Ósea/efectos de los fármacos , Citocinas/farmacología , Interferón-alfa/farmacología , Animales , Línea Celular , Citocinas/toxicidad , Hematopoyesis/efectos de los fármacos , Interferón-alfa/toxicidad , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BLRESUMEN
Limitin has sequence homology with alpha interferon (IFN-alpha) and IFN-beta and utilizes the IFN-alpha/beta receptor. However, it has no influence on the proliferation of normal myeloid and erythroid progenitors. In this study, we show that limitin has antiviral activity in vitro as well as in vivo. Limitin inhibited not only cytopathic effects in encephalomyocarditis virus- or herpes simplex virus (HSV) type 1-infected L929 cells, but also plaque formation in mouse hepatitis virus (MHV) type 2-infected DBT cells. In addition, administration of limitin to mice suppressed MHV-induced hepatitis and HSV-induced death. The antiviral activity may be mediated in part by 2',5'-oligoadenylate synthetase, RNA-dependent protein kinase, and Mx protein, which inhibit viral replication or degrade viral components, because limitin induced their mRNA expression and enzyme activity. While limitin has antiviral activity as strong as that of IFN-alpha in vitro (the concentration that provided 50% inhibition of cytopathic effect is approximately 30 pg/ml), IFN regulatory factor 1 (IRF-1) dependencies for induction of an antiviral state were different for limitin and IFN-alpha. In IRF-1-deficient fibroblasts, a higher concentration of limitin than of IFN-alpha was required for the induction of antiviral activity and the transcription of proteins from IFN-stimulated response element. The unique signals and the fewer properties of myelosuppression suggest that a human homolog of limitin may be used as a new antiviral drug.
Asunto(s)
Antivirales/farmacología , Citocinas/farmacología , Proteínas de Unión al ADN/fisiología , Virus de la Encefalomiocarditis/efectos de los fármacos , Herpesvirus Humano 1/efectos de los fármacos , Interferón Tipo I/farmacología , Virus de la Hepatitis Murina/efectos de los fármacos , Fosfoproteínas/fisiología , Animales , Línea Celular , Efecto Citopatogénico Viral/efectos de los fármacos , Virus de la Encefalomiocarditis/patogenicidad , Virus de la Encefalomiocarditis/fisiología , Regulación de la Expresión Génica/efectos de los fármacos , Herpesvirus Humano 1/patogenicidad , Herpesvirus Humano 1/fisiología , Factor 1 Regulador del Interferón , Ratones , Virus de la Hepatitis Murina/patogenicidad , Virus de la Hepatitis Murina/fisiología , Proteínas Recombinantes/farmacología , Replicación Viral/efectos de los fármacosRESUMEN
Several reports have described "multifunctional" eukaryotic mRNAs producing more than one protein through alternative translational initiation at multiple AUG codons. There are 2 such codons in the 5' region of our recently cloned limitin gene where 2 open reading frames overlap by 34 nucleotides. The deduced protein translated from the first ATG contains 33 amino acids, lacks a signal peptide, and has no obvious effects on the transfected 293T cells. We found that the second ATG is more effective as a translational initiation site than the first ATG and yields a secreted protein of 182 amino acids with the same activity as products made with full-length limitin cDNA. Immunohistochemical and reverse transcription-polymerase chain reaction analysis revealed that the longer limitin protein is produced by mature T lymphocytes in spleen and thymus as well as by bronchial epithelial and salivary duct cells in healthy mice. Properties of recombinant limitin were determined, revealing it to be a serologically distinct, heat- and acid-stable, heparin-binding glycoprotein with the potential for dimerization. Although the longer limitin protein is structurally and characteristically related to type I interferons, its production is uniquely regulated by translation as well as transcription.