Post Doctorate Fellows - Clarice Nishio

Clarice Nishio

Enamel matrix proteins regulate formation of the enamel layer that covers the crowns of teeth. Recent efforts by our laboratory have led to the identification of a novel protein secreted by the ameloblasts during the maturation stage, called Apin. This protein is also found at the level of the junctional eptithelium, a specialized epithelium believed to be derived from reduced enamel organ and which seals the gingiva to the tooth surface. In addition, Apin has been highly upregulated and isolated in different epithelial tumors, such as in the calcifying epithelial odontogenic tumor. The role and mechanism by which this protein exerts its activity remain unclear.

Therefore, the purpose of my research project is to gain a more comprehensive view of the Apin function and its biochemical characteristics.

 

(2006-2008) Doctor of Dentistry (Orthodontics), State University of Rio de Janeiro, Brazil.

(2006 -2007) Research fellow at the Department of Orthodontic and Craniofacial Development Biology, University of Hiroshima, Japan.

(2004-2005) Master of Dentistry (Orthodontics), State University of Rio de Janeiro, Brazil.

(2000-1998) Postgraduation in Orthodontics, Federal University of Niterói, Brazil.

(1997-1997) Postgraduation in Pediatric Dentistry, Federal University of Rio de Janeiro, Brazil.

(1992-1996) Dental Program Graduation, Federal University of Rio de Janeiro, Brazil.

 

Nishio C, Tanimoto K, Hirose M, Horiuchi S, Kuroda S, Tanne K, Tanaka E. (2009): Stress analysis in the mandibular condyle during prolonged clenching: a theoretical approach with the finite-element method. Proc Inst Mech Eng Part H-J Eng Med, 223:739-748.Parafunctional habits, such as bruxism and prolonged clenching, have been associated with functional overloading in the temporomandibular joint (TMJ), which may result in internal derangement and osteoarthrosis of the TMJ. In this study, the distributions of stress on the mandibular condylar surface during prolonged clenching were examined with TMJ mathematical models. Finite element models were developed on the basis of magnetic resonance images from two subjects with or without anterior disc displacement of the TMJ. Masticatory muscle forces were used as a loading condition for stress analysis during a 10 min clenching. In the asymptomatic model, the stress values in the anterior area (0.100 MPa) and lateral area (0.074 MPa) were relatively high among the five areas at 10min. In the middle and posterior areas, stress relaxation occurred during the first 2 min. In contrast, the stress value in the lateral area was markedly lower (0.020 MPa) than in other areas in the symptomatic model at 10 min. The largest stress (0.050MPa) was located in the posterior area. All except the anterior area revealed an increase in stress during the first 2 min. The present result indicates that the displacement of the disc could affect the stress distribution on the condylar articular surface during prolonged clenching, especially in the posterior area, probably leading to the cartilage breakdown on the condylar articular surface.

Nishio C , Mendes A.M. , Almeida M.A.O. , Tanaka E. , Tanne K. , Elias C.N. (2009) Evaluation of aesthetic brackets’ resistance to torsional forces from archwire. Am. J. Orthod. Dentofacial Orthop., 135: 42-8.The aim of this study was to evaluate the resistance to deformation or fracture of esthetic brackets produced by archwire torsion. Methods: Six types of maxillary right central incisor brackets were analyzed: traditional ceramic brackets (cer); ceramic brackets reinforced with a stainless steel slot (cer/ss); ceramic brackets reinforced with a gold slot (cer/gold); traditional polycarbonate brackets (poly); polycarbonate brackets reinforced with a stainless steel slot (poly/ss); and polycarbonate brackets reinforced with ceramic fillers and a stainless steel slot (poly/cer/ss). Stainless steel wire segments were used, and the testing instrument (Emic DL 10000, São José do Rio Preto, PR, Brazil) was moved at a rate of 1 inch per minute to generate the wire torsion...

Ueki M., Tanaka N., Tanimoto T., Nishio C., Honda K., Lin Y.Y., Tanne Y., Ohkuma S., Kamiya T., Tanaka E., Tanne K. (2008) The effect of mechanical loading on the metabolism of growth plate chondrocytes. Ann. Biomed. Eng., doi: 10.1007/s10439-008-9462-7.It is well known that mechanical loading influences the endochondral bone formation essential for the growth and development of longitudinal bones. The question was, however, asked whether the effect of mechanical loading on the chondrocyte metabolism is dependent on the loading frequency. This study was aimed at evaluating the effect of tensile loadings with various frequencies on the proliferation of growth plate chondrocytes and extracellular matrix synthesis. The chondrocytes obtained from rib growth plate cartilage of 4-week-old male Wistar strain rats were cultured by day 4 and day 11 and used as proliferating and matrixforming chondrocytes, respectively. Intermittent tensile stresses with different frequencies were applied to each stage chondrocyte. DNA syntheses were examined by measuring the incorporation of [3H]thymidine into the cells.....

Tanaka E., Sasaki A., Hasegawa T., Nishio C., Kawa N., Tanne K. (2008) Skeletal anchorage system for orthodontic correction of severe maxillary protrusion with previous experience of orthodontic treatment. Angle Orthod., 78: 181-188.The correction of a severe maxillary protrusion in an adult by distal movement of the maxillary molars has been one of the most difficult biomechanical problems in orthodontics. This article reports on the treatment of an adult case of severe maxillary protrusion and a large overjet treated with a skeletal anchorage system. A female patient, age 22 years and 3 months, complained of the difficulty of lip closure due to severe maxillary protrusion with a gummy smile. Overjet and overbite were 7.6 mm and 0.9 mm, respectively. She had a history of orthodontic treatment in which her maxillary first premolars were extracted. In order to conduct distal movement of the maxillary molars, anchor plates were placed in the zygomatic process. After achieving a Class I molar relationship, retraction and intrusion of the maxillary incisors were performed. After a 2-year treatment, an acceptable occlusion was achieved with a Class I molar relationship...

Freire S.M., Nishio C., Mendes A.M., Quintao C.C.A., Almeida M.A.O. (2007) The relation between dental size and normal occlusion in Brazilians. Braz. Dental J., 18: 253-257.The present study was performed on dental casts and lateral cephalometric films of 30 Caucasian Brazilian individuals (15 males and 15 females) aged 18 to 27 years and 4 months, all presenting normal occlusion and satisfactory facial profile. The aims were to investigate the existence of dental discrepancies according to Bolton's criteria, to obtain mean values for overbite, overjet, curve of Spee and interincisal angle, and to demonstrate any correlation among these parameters. A single calibrated operator measured each variable characteristics and the process was recorded twice with an accurate modified digital caliper. It was observed that the sample of normal occlusion did not present any dental discrepancy among the 12 teeth of opposite arches. The overall ratio (91.46) and anterior ratio (77.83) were in accordance with those proposed by Bolton....

Galvão M.A.B, Cabral A.C, Nishio C., Capelli Jr. J. (2007) Orthodontic Management of a Transposed Maxillary Canine and Lateral Incisor. J. Clin. Orthod., 41: 377-381.

Nishio C., Motta A.F.J., Mucha J.N., Elias C.N. (2004) In vitro evaluation of frictional forces between archwires and ceramic brackets. Am. J. Orhod. Dentofacial Orthop. 125: 56-64.The aim of this study was to evaluate the frictional force between orthodontic brackets and archwires. The differences in magnitude of the frictional forces generated by ceramic brackets, ceramic brackets with metal reinforced slot, and stainless steel brackets in combination with stainless steel, nickel-titanium, and beta-titanium orthodontic archwires were investigated. Brackets and wire were tested with tip angulations of 0° and 10°. Friction testing was done with the Emic DL 10000 testing machine (Sa~ o Jose´ do Rio Preto, PR, Brazil), and the wires were pulled from the slot brackets with a speed of 0.5 cm/min for 2 minutes. The ligation force between the bracket and the wire was 200 g. According to the data obtained, the brackets had frictional force values that were statistically significant in this progressive order: stainless steel bracket, ceramic bracket with a metal reinforced slot, and traditional ceramic bracket with a ceramic slot. The beta-titanium wire showed the highest statistically significant frictional force value, followed by the nickel-titanium and the stainless steel archwires, in decreasing order...

Silva D.B., Nishio C., Bastos E.P., Gleiser R. (1998) [Talon cusp and dens in dente in a torsionversion lateral incisor: orthodontic treatment.] J. Bras. Orthod. Orthop. Facial, 3: 71-75.

 

Shingo Kuroda

Immediate implant loading produces micromotion at the bone-implant interface, which can lead to fibrous or fibrocartilaginous encapsulation and implant failure. There is an incomplete understanding of the key physical factors and underlying mechanisms that influence cell fate decisions at the bone-implant interface. Our working hypothesis is that deformation in healing tissue regulates cell fate decisions at the bone-implant interface. To test this hypothesis, we try to implant a micromotion device in an animal model and measure the cellular response to different mechanical stimuli using molecular, cellular, and genetic approaches. Our project will contribute scientific insight that can guide placement and design decisions with skeletal implants.

 

(2008-Present) Associate Professor, Department of Orthodontics and Dentofacial Orthopedics, The Tokushima University Graduate School of Oral Sciences, Japan.

(2000-2008) Assistant Professor, Department of Orthodontics and Dentofacial Orthopedics, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Japan.

 

(1996-2000) Doctor of Philosophy in Dental Science , Doctoral program, Osaka University Graduate School of Dentistry, Japan.

(1990-1996) Doctor of Dental Surgery, Osaka University, Japan.

 

Kuroda S, Tanimoto K, Izawa T, Fujihara S, Koolstra JH, Tanaka E. (2009): Biomechanical and biochemical characteristics of the mandibular condylar cartilage. Osteoarthritis and Cartilage, 17:1408-1415

Takano-Yamamoto T, Kuroda S. (2009): Diagnostic et traitement de patients adultes présentant une asymétrie faciale. L'Orthodontie Française, 80:313-329.

Kuroda S, Tanaka E. Application of TADs for treatment of adult Class III malocclusion. Seminars in Orthodontics, in press.

Kuroda S, Fujii A, Sugie M, Uoi S, Kondo K, Ando R, Yamashiro T. Relationships between orthodontic expertise and perception of treatment needs for maxillary protrusion: comparison of dental students, residents, and orthodontists. Am J Orthod Dentofacial Orthop, in press.

Kuroda S, Okada T, Ishimitsu T, Tanimoto Y, Miyawaki S, Takano-Yamamoto T. (2009): Longitudinal craniofacial changes in subjects with untreated maxillary protrusion and mandibular protrusions in the third decade of life. Orthod Waves, 68: in press.

Kuroda Y, Kuroda S, Alexander RG, Tanaka E. Adult Class III treatment using a J-hook headgear to the mandibular arch. Angle Orthod, in press.

Yanagita T, Kuroda S, Takano-Yamamoto T, Yamashiro T. Class III malocclusion with complex problems of lateral open bite and severe crowding successfully treated using miniscrew anchorage and lingual orthodontic brackets. Am J Orthod Dentofacial Orthop, in press.

Ohura R, Kuroda S, Takahashi T, Kondo Y, Tanaka E. Efficient usage of implant anchorage in treatment of Angle Class II malocclusion with overerupted maxillary first molar and mesially inclined mandibular molars. Am J Orthod Dentofacial Orthop, in press.

Hashimoto T, Fukunaga T, Kuroda S, Sakai Y, Yamashiro T, Takano-Yamamoto T. Mandibular deviation and canted maxillary occlusal plane treated with miniscrews and intraoral vertical ramus osteotomy: Functional and morphologic changes. Am J Orthod Dentofacial Orthop, in press.

Kondo Y, Takahashi T, Oba Y, Kuroda S, Moriyama K, Tanaka E. (2009): Blood flow distribution of repaired lip in cleft lip patients. Angle Orthod, 79:1182-1187.

Sakai Y, Kuroda S, Tamamura N, Yamashiro T, Takano-Yamamoto T. (2009): A case of severe crowding with nickel allergy treated using non-nickel-containing orthodontic appliances. Orthodontic Waves, 68:129-136.

Nishio C, Tanimoto K, Hirose M, Horiuchi S, Kuroda S, Tanne K, Tanaka E. (2009): Stress analysis in the mandibular condyle during prolonged clenching: a theoretical approach with the finite-element method. Proc Inst Mech Eng Part H-J Eng Med, 223:739-748.

Kitase Y, Yokozeki, Fujihara S, Izawa T, Kuroda S, Tanimoto K, Moriyama K, Tanaka E. (2009): Analysis of gene expression profiles in human periodontal ligament cells under hypoxia: The protective effect of CC chemokine ligand 2 to oxygen shortage. Arch Oral Biol, 54:618-624.

Kuroda S, Murakami K, Morishige Y, Takano-Yamamoto T. (2009): Severe Class II malocclusion with facial asymmetry treated with intra-oral vertico-sagittal ramus osteotomy and LeFort I osteotomy. Am J Orthod Dentofacial Orthop, 135:809-819.

Tamamura N, Kuroda S, Sugawara Y, Takano-Yamamoto T, Yamashiro T. (2009): Use of palatal miniscrew anchorage and lingual multi-bracket appliances to enhance efficiency of molar scissors-bite correction. Angle Orthod, 79:577-584

Sakai Y, Balam TA, Kuroda S, Tamamura N, Fukunaga T, Takigawa M, Takano-Yamamoto T. (2009): CTGF and apoptosis in mouse osteocytes induced by tooth movement. J Dent Res, 88:345-350.

Hashimoto T, Kuroda S, Kamioka H, Mishima K, Sugahara T, Takano-Yamamoto T. (2009): Bimaxillary protrusion with massater muscle hypertrophy treated with titanium screw anchorage and masseter surgical reduction. Am J Orthod Dentofacial Orthop, 135:536-548.

Kuroda S, Yamada K, Deguchi T, Kyung HM, Takano-Yamamoto T. (2009): Class II malocclusion treated with miniscrew anchorage: comparison with traditional orthodontic mechanics outcomes. Am J Orthod Dentofacial Orthop, 135:302-309.

Yamada K, Kuroda S, Deguchi T, Takano-Yamamoto T, Yamashiro T. (2009): Distal movement of maxillary molars using miniscrew anchorage in the buccal interradicular region. Angle Orthod, 79:78-84.

Kuroda S, Sugahara T, Takabatake S, Taketa H, Ando R, Yamada K, Takano-Yamamoto T. (2009): Influence of anteroposterior mandibular positions on facial attractiveness in Japanese adults. Am J Orthod Dentofacial Orthop, 135:73-78.

Hashimoto T, Kuroda S, Lihua E, Tanimoto Y, Miyawaki S, Takano-Yamamoto T. (2008): Correlation between craniofacial and condylar path asymmetry. J Oral Maxillofacial Surg, 66:2020-2027.

Deguchi T, Murakami T, Kuroda S, Yabuuchi T, Kamioka H, Takano-Yamamoto T. (2008): Comparison of the intrusion effects on the maxillary incisors between implant anchorage and J-hook headgear. Am J Orthod Dentofacial Orthop, 133:654-660.

Sugawara Y, Kuroda S, Tamamura N, Takano-Yamamoto T. (2008): Adult patient with mandibular protrusion and unstable occlusion treated using titanium screw anchorage. Am J Orthod Dentofacial Orthop, 133:102-111.

Sakai Y, Kuroda S, Murshid SA, Takano-Yamamoto T. (2008): Skeletal Class III severe open bite treatment using implant anchorage. Angle Orthod, 78:157-166.

Kuroda S, Sakai Y, Tamamura N, Deguchi T, Takano-Yamamoto T. (2007): Treatment of severe anterior open bite with skeletal anchorage in adults: Comparison with orthognathic surgery outcomes. Am J Orthod Dentofacial Orthop, 132:599-605.

Takano-Yamamoto T, Kuroda S. (2007): Titanium screw anchorage for correction of canted occlusal plane in patients with facial asymmetry. Am J Orthod Dentofacial Orthop, 132:237-242.

Kuroda S, Yanagita T, Kyung HM, Takano-Yamamoto T. (2007): Titanium screw anchorage for traction of many impacted teeth in a patient with cleidocranial dysplasia. Am J Orthod Dentofacial Orthop, 131:666-669.

Kuroda S, Yamada K, Deguchi T, Hashimoto T, Kyung HM, Takano-Yamamoto T. (2007): Root proximity is a major factor for screw failure in orthodontic anchorage. Am J Orthod Dentofacial Orthop, 131:S68-73.

Kuroda S, Sugawara Y, Tamamura N, Takano-Yamamoto T. (2007): Anterior open bite with temporomandibular disorder treated with titanium screw anchorage: Evaluation of morphological and functional improvement. Am J Orthod Dentofacial Orthop, 131:550-560.

Kuroda S, Sugawara Y, Deguchi T, Kyung HM, Takano-Yamamoto T. (2007): Clinical use of miniscrew implants as orthodontic anchorage: success rates and postoperative discomfort. Am J Orthod Dentofacial Orthop, 131:9-15.

Fukunaga T, Kuroda S, Kurosaka H, Takano-Yamamoto T. (2006): Skeletal anchorage for orthodontic correction of maxillary protrusion with adult periodontitis. Angle Orthod, 76:148-155.

Kuroda S, Sugawara Y, Yamashita K, Mano T, Takano-Yamamoto T. (2005): Skeletal Class III oligodontia patient treated with titanium screw anchorage and orthognathic surgery. Am J Orthod Dentofacial Orthop, 127:730-738.

Kuroda S, Araki Y, Oya S, Mishima K, Sugawara T, Takano-Yamamoto T. (2005): Maxillary distraction osteogensis to treat maxillary hypoplasia: Comparison of an internal and an external system. Am J Orthod Dentofacial Orthop, 127:493-498.

Kuroda S, Kuroda Y. (2005): Nonextraction treatment of upper canine-premolar transposition in an adult patient. Angle Orthod, 75:421-426.

Kuroda S, Balam TA, Sakai Y, Tamamura N, Takano-Yamamoto T. (2005): Expression of osteopontin mRNA in odontoclasts revealed by in situ hybridization during experimental tooth movement in mice. J Bone Miner Metab, 23:110-113.

Kuroda S, Katayama A, Takano-Yamamoto T. (2004): Severe anterior open-bite case treated using titanium screw anchorage. Angle Orthod, 74:558-567.

Kuroda S, Kuboki T, Katayama A, Takano-Yamamoto T. (2003): Use of a porcelain laminate veneer for esthetic improvement after orthodontic treatment. Orthod Waves, 62:437-438.

Minato M, Miyawaki S, Tanimoto Y, Kuroda S, Yasuda Y, Takano-Yamamoto T. (2002): An adult case untreated for 7 years after loss of the mandibular left first molar. Orthod Waves, 61:466-470.

Kawakami M, Kuroda S, Yoshida CA, Yamashita K, Takada K. (2000): Dental follicle cell-conditioned medium enhances the formation of osteoclast-like multinucleated cells. Eur J Orthod , 22:675-682.

Kawakami M, Kuroda S, Yamashita K, Yoshida CA, Nakagawa K, Takada K. (1999): Expression of CSF-1 receptor on TRAP-positive multinuclear cells around the erupting molars in rats. J Craniofac Genet Dev Biol, 19:213-220.

 

Post Doctorate Fellows - Michela Zago

 

Michela Zago

My project focuses on bone sialoprotein (BSP) whose spatiotemporal pattern of expression has been linked with initial mineralization. Using in vitro assays, two N-terminal half glutamic acid rich regions (poly [E]) were identified as domains partially responsible for its mineral nucleating activity. Our hypothesis is that poly [E] sequences and flanking glutamic acid-rich regions on BSP collaborate to promote osteogenic activity and mineralization. The objectives of this project is to evaluate, in the biological environment of the body and under physiological conditions, the role of these functional domains of BSP on specific bone parameters by overexpressing various mutant forms of the proteins in forming bone. We will produce different BSP mutant constructs in which the poly [E] domains will be replaced with polyalanine by site-directed mutagenesis and cloned them into the lentiviral vector. These viruses will be infused in  rat tibia and a combination of histological and molecular approaches will be used to determine the effect of these BSP variants on osteogenic cell activity, on the structuring and mineralization of bone matrix, and on its subsequent resorption.

(2005-2007) Doctor of Philosophy in Human Morphological and Molecular Science, Università degli Studi di Bologna, Italia.

(1998-2004) Bachelor in Pharmacy, Università degli Studi di Bologna, Italia.

 

Mazzotti G, Falconi M, Teti G, Zago M, Lanari M, Manzoli FA. (2009). The diagnosis of the cause of the death of Venerina. J Anat. In Press.

Falconi M, Teti G, Zago M, Galanzi A, Breschi L, Pelotti S, Ruggeri A, Mazzotti G. (2009). Influence of a commercial tattoo ink on protein production in human fibroblasts. Arch Dermatol Res.; 301: 539-47.Tattooing is an ancient art and is still widely practiced all over the world. Since the biocompatibility of tattoo dyes has not been well researched, we studied the toxicity of a commercial tattoo ink, commonly used in tattoo lab and esthetic centers, on human Wbroblasts. To test cell viability, MTT assays were carried out and scanning electron microscopy to visualize changes in the cell surface after the dye exposure was performed. A possible inXuence of the pigment on the expression of procollagen alpha1 type I protein was visualized by western blotting analysis. The results showed a reduction in cell viability, and electron microscopy demonstrated an unmodiWed cell surface completely covered by pigment particles. Western blotting analysis demonstrated a clear interference of the pigment on the expression of procollagen alpha1 type I protein.

Teti G., Mazzotti G., Zago M., Ortolani M., Breschi L., Pelotti S., Ruggeri A., Falconi M. (2009). HEMA down-regulates procollagen alpha1 type I in human gingival fibroblasts. J Biomed Mater Res A.; 90: 256-62.2-Hydroxyethyl methacrylate (HEMA) can be released from restorative materials and diffused into the tooth pulp over long periods of time. Although cytotoxicity due to high concentrations of monomers has been well studied, little is known about the risk of chronic toxicity resulting from low concentrations. The purpose of the study was to evaluate the effects of a minor toxic concentration of HEMA in the synthesis and expression of procollagen a1 type I produced by human gingival fibroblasts (HGF). HGF were exposed to 3 mM HEMA from 24 to 96 h. An MTT assay was performed to evaluate cell viability while reverse-transcriptase polymerase chain reaction (RT-PCR), real-time polymerase chain reaction (real-time PCR), and Western-blot analysis were carried out to evaluate the variability in the expression and synthesis of procollagen a1. Immunofluorescence was performed to detect the protein inside the cells. The results showed that there was a strong reduction of procollagen a 1 type I expression at 72 and 96 h. These findings demonstrate that, even if it does not reduce cell viability, 3 mM HEMA interferes both with the synthesis of the procollagen a 1 type I protein and its mRNA expression, suggesting that normal cell production and activity are modified by HEMA at concentrations below those which cause acute cytotoxicity.

Zago M., Teti G., Mazzotti G., Ruggeri A., Breschi L., Pelotti S., Ortolani M., Falconi M. (2008). Expression of procollagen alpha1 type I and tenascin proteins induced by HEMA in human pulp fibroblasts. Toxicol In Vitro.; 22: 1153-9.In the dental pulp extracellular matrix, the main macromolecules are collagenous proteins, non-collagenous proteins and proteoglycans. Regulated synthesis of the interstitial collagens, in particular, type I collagen, is important during development and wound healing but also in a number of pathological conditions. Tenascin is also a matrix protein highly expressed during development while it decreases in mature organs. Under pathological conditions such as infections and inflammation, during tumorigenesis and mechanical stress applied to cells in culture or tissue in vivo, the expression of tenascin is increased. In this study, HEMA, widely used in dentistry, ophthalmology and drug delivery, has been used to study its influence on the expression of procollagen a1 type I and tenascin proteins in the primary cultures of human pulp fibroblasts. Different concentrations of the resin monomer and different times of exposition were tested. The influence of HEMA on the cell viability was evaluated by means of an MTT assay while immunofluorescence and western blotting analysis were performed to detect possible interference with the presence and the synthesis of these proteins. We observed a strong reduction in cell viability in specimens treated for 96 h and 168 h, especially at concentrations of 1 and 3 mmol/L HEMA. Both immunofluorescence and western blotting analysis demonstrated a reduction of procollagen a1 type I protein and an overexpression of tenascin protein. Our results showed that long-term exposure and low concentrations of HEMA influence normal cell activity, such as the synthesis of some of the dental pulp extracellular matrix proteins.

Falconi M., Teti G., Zago M., Pelotti S., Breschi L., Mazzotti G. (2007). Effects of hema on type I collagen protein in human gingival fibroblasts. Cell Biol. Toxicol.; 23: 313-22.The cytotoxicity of dental composites has been attributed to the release of residual monomers from polymerized adhesive systems due to degradation processes or the incomplete polymerization of materials. 2-Hydroxyethyl methacrylate (HEMA) is one of the major components released from dental adhesives. Cytotoxic effects due to high concentrations of HEMA have already been investigated, but the influence of minor toxic concentrations on specific proteins such as type I collagen has not been studied in depth. The objective of this project was to study the effect of minor toxic concentrations of HEMA on human gingival fibroblasts (HGFs), investigating modification in cell morphology, cell viability, and the influence on type I collagen protein. Primary lines of human gingival fibroblasts were exposed to 3 mmol/L HEMA for different periods of time (24 h, 72 h, 96 h). The cell vitality was determined by MTT assay, and high-resolution scanning electron microscopy analysis was performed to evaluate differences in cell morphology before and after treatment. The presence and localization of type I collagen was determined by immunofluorescence in HGFs treated with HEMA for the same period of time. The vitality of the cells decreased after 72 h of exposure...

Falconi M., Teti G., Zago M., Pelotti S., Gobbi P., Breschi L., Mazzotti G. (2007). Effect of fixative on chromatin structure and DNA detection. Microsc Res Tech.; 70: 599-606.In this study, we analyzed the chromatin ultrastructure in interphase cells after different chemical fixations. In light of the fact that there is little information regarding the fixation of biological samples in combination with molecular biology methods (such as DNA extraction and in situ hybridization methods) we analyzed the ultrastructure of chromatin in interphase cells fixed with different fixatives and tested under the same conditions for both DNA extraction and in situ hybridization. The results showed that, among the different combinations and concentrations we analyzed, the solution of 4% paraformaldehyde/0.1% glutaraldehyde was the best compromise in order to achieve a well-preserved morphology, successful DNA extraction, and specific signaling of in situ hybridization, suggesting a low interference of this fixative with the chromatin organization

 

©2009 Pedro A. Segura