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1.
Int J Oral Maxillofac Surg ; 46(3): 355-359, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27641810

RESUMO

A case of tophaceous pseudogout (i.e., calcium pyrophosphate dihydrate (CPPD) crystal deposition disease) in the temporomandibular joint (TMJ), extending to the base of the skull, is reported. A 38-year-old man was referred to the hospital with mild pain in the right chin and tip of the tongue. Panoramic radiography showed a large calcified mass around the right TMJ. Computed tomography imaging revealed a large, granular, calcified mass surrounding the right condylar head and extending to the base of the skull. The mass was clinically and radiographically suspected to be a pseudogout lesion. A biopsy specimen was collected under general anaesthesia to confirm the diagnosis. On histology, the mass was found to contain deposits of numerous rod-shaped and rhomboid crystals, which suggested tophaceous pseudogout. The deposits were identified as CPPD crystal deposition, based on analysis by X-ray diffraction and Fourier transform infrared spectroscopy. These two crystallography methods were useful in confirming the diagnosis of CPPD crystal deposition disease in the TMJ.


Assuntos
Condrocalcinose/diagnóstico por imagem , Transtornos da Articulação Temporomandibular/diagnóstico por imagem , Adulto , Biópsia , Diagnóstico Diferencial , Humanos , Masculino , Radiografia Panorâmica , Espectroscopia de Infravermelho com Transformada de Fourier , Tomografia Computadorizada por Raios X , Difração de Raios X
2.
J Mater Chem B ; 3(44): 8738-8746, 2015 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-32262731

RESUMO

Both bone-forming cells and immune cells have pivotal roles in bone tissue repair. In this work, we prepared a Ca-modified poly(ether ether ketone) (PEEK) to enhance the osteoconductivity but mitigate immune response of cells. To modify Ca ions onto a chemically inert PEEK, PEEK was first coated with poly(norepinephrine) followed by soaking in Ca(OH)2 aqueous solution. Modification of Ca ions onto PEEK enhanced the proliferation and differentiation of MC3T3-E1 preosteoblast cells and human mesenchymal stem cells, but had no apparent effect on MLC-6 osteoclast-like cells. Naïve RAW264.7 macrophages cultured on pristine PEEK produced proinflammatory cytokines, but not on Ca-modified PEEK. Lipopolysaccharide-stimulated RAW264.7 macrophages on Ca-modified PEEK produced lower levels of proinflammatory cytokines but higher levels of anti-inflammatory cytokines compared with those on pristine PEEK. Lower levels of proinflammatory cytokines on Ca-modified PEEK were partially owing to higher interleukin-10 production mediated by Ca-activated pathways. Simple Ca modification of PEEK was shown to activate osteoblastic cell proliferation and differentiation, and shift macrophages towards an anti-inflammatory/wound healing type, which would be useful not only for bone tissue implants but also other implanted biomaterials.

3.
J Oral Rehabil ; 35(9): 700-5, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18793354

RESUMO

The present study aimed to examine the effect of custom tray designs on the displacement of mobile tooth and local impression pressures during the impression procedure, using partially edentulous simulation models with six anterior teeth containing a mobile tooth prepared in previous studies. The custom trays were designed by altering the thickness of the respective spaces on the labial and lingual sides of the remaining tooth arch. In previous studies, the mobile tooth was displaced in the labial direction and local impression pressures of the mobile tooth were greater against the lingual side than the labial side for all custom tray designs. Furthermore, the custom trays perforated with holes on the lingual side were effective to reduce mobile tooth displacement, labial and lingual impression pressures against the mobile tooth, and the differences between them. Therefore, the present study was performed focusing on the labial and lingual thickness of spaces in custom tray designs. It was found that mobile tooth displacement, labial and lingual impression pressures against the mobile teeth and their differences were less in trays with spaces>3.0 mm thick on both the labial and lingual sides, but markedly greater in trays with a 1.5 mm-thick space on the labial side. These results indicate that the thickness of spaces on the labial side in the tray should not be reduced to prevent mobile tooth displacement.


Assuntos
Materiais para Moldagem Odontológica , Técnica de Moldagem Odontológica/instrumentação , Avulsão Dentária/complicações , Mobilidade Dentária/etiologia , Dente Canino/fisiologia , Técnica de Moldagem Odontológica/efeitos adversos , Análise do Estresse Dentário , Humanos , Incisivo/fisiologia , Arcada Parcialmente Edêntula , Maxila/fisiologia , Modelos Dentários
4.
J Biomater Appl ; 20(3): 253-66, 2006 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-16364965

RESUMO

Two MK5 (45CaO-45P(2)O(5)-5MgO-5K(2)O, in mol%) and MT13 (45CaO-37P(2)O(5)-5MgO-13TiO(2), in mol%) glasses are prepared in the meta- and pyrophosphate regions and crystallized to obtain MK5B and MT13B, respectively. MK5B was obtained by controlled crystallization, and MT13B by powder sintering. As a result of these heat treatment processes, the crystalline phases precipitated in the glassy matrix are KCa(PO(3))(3), beta-Ca(PO(3))(2), beta-Ca(2)P(2)O(7) and Ca(4)P(6)O(19) phases for MK5B and CaTi(4)(PO(4))(6), TiP(2)O(7), alpha- and beta-Ca(2)P(2)O(7) phases for MT13B. To assess the in vivo biological behavior of these glass ceramics, a mixed granulometry in the range 250-355 mum and 355-425 mum with a ratio of 1/1 was implanted for 2, 4, and 12 weeks in the tibiae of Japanese white rabbits. The results showed that the in vivo behavior was strongly affected by their solubility. All implanted materials, MK5B and MT13B, and beta-tricalcium phosphate (beta-TCP) as control material, showed signs of degradation in vivo. However, the levels of degradation were quite different throughout the implantation periods. The highest degradation was observed for MK5B glass ceramic and the lowest for MT13B with beta-TCP in-between. All implanted materials allow for new bone formation in the bone defect area. At the longest implantation period (12 weeks), the MT13B and beta-TCP materials were almost completely surrounded by new bone tissue, whereas MK5B showed some unfilled spaces. This behavior is discussed in terms of the high degradation observed in previous studies.


Assuntos
Implantes Absorvíveis , Substitutos Ósseos/análise , Substitutos Ósseos/química , Fosfatos de Cálcio/administração & dosagem , Fosfatos de Cálcio/química , Fraturas da Tíbia/tratamento farmacológico , Fraturas da Tíbia/patologia , Animais , Fosfatos de Cálcio/análise , Cerâmica/análise , Cerâmica/química , Modelos Animais de Doenças , Vidro/análise , Vidro/química , Teste de Materiais , Coelhos , Resultado do Tratamento
5.
Interv Neuroradiol ; 10 Suppl 1: 147-52, 2004 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-20587291

RESUMO

SUMMARY: We have been using the Guglielmi detachable coils (GDC) since 1997 as one choice of cerebral aneurysm treatment.We have, at the present time, two effective radical treatment methods for acutely ruptured cerebral aneurysms, GDC embolization and conventional surgical aneurysmal neck clipping. There ensued questions about the cost and efficacy of the two strategies. Retrospective analysis was done on a GDC group and a clipping group, with each twenty consecutive patients. The features of the GDC group patients were higher age, and poorer Hunt and Kosnik grades than the other group. All MCA aneurysms were treated with surgical neck clipping, while all the posterior circulation aneurysms were embolized with GDC. Based on the Japanese Medical Insurance and Payment System, 477,890 points (1 point = yen 10) as a mean was required with the GDC group, and 456,084 points with the neck clipping group, showing no significant difference between the two groups. In the GDC group, the cost of the implanted medical device seemed to raise the total medical expense. At present, the GDC embolization is the preferred choice of strategies in acutely ruptured cerebral aneurysms, and its preference increases in the surgically difficult cases, very old, or poor grade patients, and in various complicated cases. And, the GDC embolization seems to be satisfactory from the medico-financial viewpoint.

6.
Interv Neuroradiol ; 10 Suppl 1: 173-9, 2004 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-20587296

RESUMO

SUMMARY: Ruptured vertebral artery dissecting aneurysms (VADA) re-bleed frequently especially during first 24 hours, which makes the prognosis of the patients with this disease poor. Recently endovascular trapping with detachable platinum coils at an acute stage has been done for preventing re-bleeding. However, for the cases with dissecting aneurysm involving the origin of the posterior inferior cerebellar artery (PICA), these methods are hardly indicated because of the risk of ischemic complication in the PICA territory. We proposed a simple and effective therapeutic method for these cases. We occluded the affected vertebral artery (VA) near its root intending to introduce collateral blood flow from the deep cervical artery into the VA trunk. The controlled antegrade VA flow and retrograde flow from the contralateral VA make a watershed at the dissecting aneurysm, which promotes thrombosis of pseudolumen with preserving the antegrade blood flow of PICA.We treated two cases with ruptured VADA involving PICA, and in both cases thrombosis of aneurysm was obtained without any ischemic complication. This method would be considered as a treatment of choice to the cases with VADA involving PICA.

7.
Toxicology ; 189(1-2): 21-39, 2003 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-12821280

RESUMO

Solar radiation induces acute and chronic reactions in human and animal skin. Chronic repeated exposures are the primary cause of benign and malignant skin tumors, including malignant melanoma. Among types of solar radiation, ultraviolet B (290-320 nm) radiation is highly mutagenic and carcinogenic in animal experiments compared to ultraviolet A (320-400 nm) radiation. Epidemiological studies suggest that solar UV radiation is responsible for skin tumor development via gene mutations and immunosuppression, and possibly for photoaging. In this review, recent understanding of DNA damage caused by direct UV radiation and by indirect stress via reactive oxygen species (ROS) and DNA repair mechanisms, particularly nucleotide excision repair of human cells, are discussed. In addition, mutations induced by solar UV radiation in p53, ras and patched genes of non-melanoma skin cancer cells, and the role of ROS as both a promoter in UV-carcinogenesis and an inducer of UV-apoptosis, are described based primarily on the findings reported during the last decade. Furthermore, the effect of UV on immunological reaction in the skin is discussed. Finally, possible prevention of UV-induced skin cancer by feeding or topical use of antioxidants, such as polyphenols, vitamin C, and vitamin E, is discussed.


Assuntos
Antioxidantes/farmacologia , Neoplasias Induzidas por Radiação/etiologia , Neoplasias Cutâneas/etiologia , Raios Ultravioleta/efeitos adversos , Animais , Dano ao DNA , Reparo do DNA , Humanos , Neoplasias Induzidas por Radiação/genética , Neoplasias Induzidas por Radiação/prevenção & controle , Espécies Reativas de Oxigênio/efeitos adversos , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/prevenção & controle , Luz Solar/efeitos adversos
8.
Br J Dermatol ; 147(5): 994-7, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12410713

RESUMO

We report a case of localized heat urticaria in a 71-year-old woman who developed weals and loss of consciousness after taking a bath. Exposing her skin to heat at 40 degrees C or immersing her hands in water at 40 degrees C produced urticarial lesions and increased her plasma histamine level. Desensitization with hot water improved her symptoms and normalized her plasma histamine level after heat challenge. An intracutaneous injection of her serum produced no reaction, while an injection of her serum that had been heated at 40 degrees C for 15 min induced a weal flare response. Further examination revealed that the weal-inducing activity of her heated serum remained for at least for 6 h and that treatment of her serum at 60 degrees C for 2 h did not abrogate its weal-inducing activity. These findings indicate that certain materials in her serum that are activated by heat are responsible for the development of her anaphylactic and urticarial reactions and that these reactions may be mediated by histamine.


Assuntos
Temperatura Alta/efeitos adversos , Urticária/sangue , Urticária/etiologia , Idoso , Feminino , Histamina/sangue , Liberação de Histamina , Humanos , Testes Intradérmicos , Temperatura
9.
J Dermatol Sci ; 26(3): 209-16, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11390206

RESUMO

High-dose ultraviolet B (UVB) irradiation is known to induce apoptosis of keratinocytes, but low-dose UVB dose not. In this paper we present evidence that low-dose UVB can induce TNF-alpha-dependent apoptosis of keratinocytes. In our study, 5 mJ/cm(2) doses of UVB were not sufficient by themselves to induce apoptosis of cultured human keratinocytes, but 20 mJ/cm(2) doses of UVB were. The combination of 5 mJ/cm(2) doses of UVB and exogenous TNF-alpha (15 ng/ml) induced significant apoptosis of keratinocytes, although exogenous TNF-alpha without UVB did not. This phenomenon was accompanied by enhanced clustering of tumor necrosis factor receptor 1 (TNFR1). TNF-alpha's promotion of the induction of apoptosis by low-dose UVB was seen until 30 min after irradiation but not at 1 h. We confirmed this finding using a skin organ culture system. UVB (20 mJ/cm(2)), which did not induce transformation of epidermal keratinocytes into sunburn cells, induced apoptosis when TNF-alpha was added to the culture medium. These results suggest that one of the possible mechanisms of inducing keratinocyte apoptosis by low-dose UVB and TNF-alpha is that low-dose UVB augments ligand-binding-induced TNFR1 clustering, resulting in increased apoptotic cell death.


Assuntos
Apoptose , Queratinócitos/efeitos dos fármacos , Queratinócitos/efeitos da radiação , Fator de Necrose Tumoral alfa/fisiologia , Raios Ultravioleta , Antígenos CD/efeitos dos fármacos , Antígenos CD/fisiologia , Antígenos CD/efeitos da radiação , Relação Dose-Resposta à Radiação , Humanos , Técnicas de Cultura de Órgãos , Agregação de Receptores , Receptores do Fator de Necrose Tumoral/efeitos dos fármacos , Receptores do Fator de Necrose Tumoral/fisiologia , Receptores do Fator de Necrose Tumoral/efeitos da radiação , Receptores Tipo I de Fatores de Necrose Tumoral , Pele/citologia , Pele/efeitos dos fármacos , Pele/efeitos da radiação
10.
Biomaterials ; 22(9): 875-81, 2001 May.
Artigo em Inglês | MEDLINE | ID: mdl-11311005

RESUMO

Apatite formation on implants is important in achieving a direct bonding to bone tissue. We recently showed that titanium metal chemically treated with a hydrogen peroxide solution containing tantalum chloride has the ability to form a hydroxyapatite layer in simulated body fluid which had inorganic ion composition similar to human blood plasma. In this study, a pure titanium cylinder (4.0 mm in diameter, 20.0 mm in length) treated with this method was implanted into a hole (4.2 mm in diameter) in a rabbit's tibia. After implantation for predetermined periods up to 16 weeks, the specimens were extracted with bone tissue, and were examined by push-out test to evaluate the shearing force between the implant and bone tissue. The results were compared with those of non-treated pure titanium. Eight weeks after surgery, the shearing force of the treated titanium implanted in the 4.2 mm-hole was significantly higher than that of non-treated titanium, although the surface roughness was not changed after the treatment. Scanning electron microscopic (SEM) observation and energy-dispersive X-ray (EDX) microanalysis showed that the bone comes very close to the surface of the treated titanium. Moreover, the shearing force was higher for the implanted sample in the 4.0 mm-hole than that in the 4.2 mm-hole. Thus, it is confirmed that the treatment with hydrogen peroxide solution containing tantalum chloride provides higher bonding ability on titanium implants in vivo.


Assuntos
Materiais Biocompatíveis , Osso e Ossos , Cloretos/química , Peróxido de Hidrogênio/química , Tantálio/química , Titânio , Animais , Microscopia Eletrônica de Varredura , Coelhos , Titânio/química
11.
Ann N Y Acad Sci ; 947: 429-32, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11795308

RESUMO

To clarify the involvement of peroxisome proliferator-activated receptors (PPARs) in atherosclerotic plaque formation, we investigated the expression patterns of mRNA and protein of PPARalpha and PPARgamma in human aorta. Atheromatous plaque, fatty streak, and diffuse intimal thickening (DIT) were separated macroscopically, and each sample was divided into halves. Half of them were used for analysis of mRNA expression with reverse transcription-polymerase chain reaction and the others were used for histologic analysis. Both PPARalpha and PPARgamma mRNA were detected in all atheromatous plaques, all fatty streaks, and in some DIT. However, expressions of PPARalpha and PPARgamma were obviously less frequently found in DIT than in atheromatous plaques, and the intensity of these expressions was stronger in the atheromatous plaques than in the DIT. Compared with PPARalpha, PPARgamma mRNA was expressed more frequently in atheromatous plaques. In atheromatous plaques, PPARgamma mRNA was expressed independently, whereas PPARalpha mRNA was coexpressed with PPARgamma. PPARgamma protein was obviously found in the nuclei of endothelial cells, macrophages, mononuclear cells, and smooth muscle cells in the aortic intima. These results suggest that expressions of PPARalpha and PPARgamma in human aortic wall are involved in atherogenesis from the early stages.


Assuntos
Arteriosclerose/fisiopatologia , Receptores Citoplasmáticos e Nucleares/classificação , Fatores de Transcrição/classificação , Arteriosclerose/patologia , Humanos , Reação em Cadeia da Polimerase , Isoformas de Proteínas/análise , Isoformas de Proteínas/classificação , Isoformas de Proteínas/genética , Receptores Citoplasmáticos e Nucleares/análise , Receptores Citoplasmáticos e Nucleares/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de Transcrição/análise , Fatores de Transcrição/genética
12.
J Biomed Mater Res ; 54(2): 172-8, 2001 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11093176

RESUMO

Commercially pure titanium specimens are subjected to three different treatments, and their bioactivity are evaluated by immersing the specimens in a simulated body fluid (SBF, Kokubo's recipe) for various periods up to 7 days, with particular attention being paid to the differences in apatite deposition between surfaces open to SBF and surfaces in contact with the container's bottom. The treatment with a H(2)O(2)/HCl solution at 80 degrees C for 30 min followed by heating at 400 degrees C for 1 h produces an anatase titania gel layer on the specimen surface. This gel layer deposits apatite both on the contact and on open surfaces, and apatite deposition ability does not change with pre-staking in distilled water. The treatment with a NaOH solution at 60 degrees C for 3 days produces a sodium titanate gel layer. This gel layer can deposit apatite only on the contact surface, and the apatite deposition ability is completely lost after 1 day of pre-staking in distilled water. It is concluded, therefore, that the bioactivity of the titania gel originates from the favorable structure of the gel itself while the bioactivity of the sodium titanate gel depends heavily on ion release from the gel. The third treatment, a simple heat treatment at 400 degrees C for 1 h, produces a dense (not porous) oxide layer on the specimen surface. The specimens can deposit apatite on the contact surface after only 3 days of staking in SBF, but they cannot deposit apatite on the open surface for up to 2 months of staking. The implications of such apatite deposition behavior have been discussed in relation to the environments of titanium implants in bone as well as to the methodology of the SBF staking experiment.


Assuntos
Apatitas/química , Peróxido de Hidrogênio , Hidróxido de Sódio , Titânio/química , Materiais Biocompatíveis/química , Líquidos Corporais , Temperatura Alta , Microscopia Eletrônica de Varredura , Modelos Biológicos , Propriedades de Superfície
13.
J Biomed Mater Res ; 52(1): 171-6, 2000 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-10906689

RESUMO

Commercially pure titanium was treated with a H(2) O(2)/3mM TaCl(5) solution at 80 degrees C for various periods and a titania gel layer was formed on the surface. This gel remained amorphous when heating for 1 h below 200 degrees C and transformed to anatase after heating between 300 degrees and 600 degrees C. The anatase titania gel layers were found to be bioactive as to deposit carbonate ion-incorporated apatite within 1 day of immersion in the Kokubo solution, whereas the amorphous layers did not deposit apatite within 7 days. The apatite particles were found to nucleate preferentially inside the cracks prevailing in the thicker gel layers of 1-h chemically treated specimens. After immersing for 2 days, the titanium specimens were almost completely covered by apatite. Elimination of peroxide radicals from the titania gel and formation of anatase upon subsequent heating are considered to be responsible for the enhanced ability of apatite deposition.


Assuntos
Materiais Biocompatíveis , Titânio , Apatitas , Temperatura Alta , Propriedades de Superfície
14.
J Oral Rehabil ; 27(5): 380-6, 2000 May.
Artigo em Inglês | MEDLINE | ID: mdl-10887910

RESUMO

The purpose of the present study was to examine the effect of custom tray designs on local pressures against teeth during the impression procedure. In a previous study, a partially edentulous simulation model with a mobile tooth was used, and the effect of custom tray designs on the displacement of the mobile tooth was examined during the impression procedure. Based on that study's results, we have assumed that the differences in impression pressures between the labial and the lingual sides of a mobile tooth could either cause or affect displacement. The present study was undertaken to determine the local impression pressures against each side of three anterior teeth, including one mobile tooth, using the same simulation model and the same custom trays as in the previous study. It was found that the local pressures exerted against teeth during the impression procedure were affected by the custom tray designs and varied according to the coronal shape, axis inclination and location of the teeth.


Assuntos
Técnica de Moldagem Odontológica/instrumentação , Arcada Parcialmente Edêntula/fisiopatologia , Modelos Dentários , Avulsão Dentária/etiologia , Mobilidade Dentária/complicações , Análise de Variância , Dente Canino/fisiopatologia , Técnica de Moldagem Odontológica/efeitos adversos , Análise do Estresse Dentário , Desenho de Equipamento , Humanos , Incisivo/fisiopatologia , Mandíbula , Reprodutibilidade dos Testes
15.
J Toxicol Sci ; 25 Spec No: 223-32, 2000 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11349447

RESUMO

To assess the validity and limitations of 2-week repeated daily dosing to detect toxic effects on male reproductive organs in rodents, a comparative 2- and 4-week oral repeated dosing study of boric acid, a known testicular toxicant, was given to 6- or 8-week-old Crj:Wistar rats at daily levels of 0, 125, 250 and 500 mg/kg. The ages of the rats were selected so that they were all sacrificed at 10 weeks of age. The testes and epididymides were weighed at necropsy; histopathological specimens were prepared in a routine manner and stained with H&E or PAS-H. In addition, the sperm number and motility rates were evaluated. There were no boric acid-induced effects on reproductive organ weights and on gross behavior/appearance in any groups in either the 2- or 4-week studies. The sperm number and motility rate were not decreased in any group after 2 weeks, while both decreased in the 250 and 500 mg/kg groups after 4 weeks. Histopathologically, as evidence of toxicity at the early stage of boric acid exposure, retention of step 19 spermatids of stages IX-XI was observed in the testes of almost all rats treated with 500 mg/kg after both 2 weeks and 4 weeks. Degenerative/necrotic germ cells and multinucleated giant cell formation were observed in 2 weeks, though to a lesser extent than in 4 weeks. On stage analysis of germinal cells in 2 weeks, spermatogonia and spermatids of stage VII were found to be decreased, and pachytene spermatocytes of stage X were increased. In conclusion, the results indicate that if the selection of doses is appropriate, testicular toxicity of boric acid can be detected even after only 2 weeks of repeated daily oral treatment.


Assuntos
Ácidos Bóricos/toxicidade , Testículo/efeitos dos fármacos , Administração Oral , Animais , Peso Corporal/efeitos dos fármacos , Ácidos Bóricos/administração & dosagem , Relação Dose-Resposta a Droga , Epididimo/efeitos dos fármacos , Epididimo/patologia , Masculino , Tamanho do Órgão/efeitos dos fármacos , Próstata/efeitos dos fármacos , Próstata/patologia , Ratos , Ratos Wistar , Glândulas Seminais/efeitos dos fármacos , Glândulas Seminais/patologia , Epitélio Seminífero/efeitos dos fármacos , Epitélio Seminífero/patologia , Contagem de Espermatozoides , Motilidade dos Espermatozoides/efeitos dos fármacos , Espermatogênese/efeitos dos fármacos , Testículo/patologia , Testículo/fisiopatologia , Fatores de Tempo , Testes de Toxicidade
18.
J Mater Sci Mater Med ; 9(8): 479-84, 1998 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15348861

RESUMO

Polymer materials for clinical applications should be bioactive and have a bone-bonding ability. In order to provide poly(methyl methacrylate) (PMMA) with bioactivity, granules (<45 microm) of a bioactive glass 50CaO.50SiO2 (mol %) were implanted into PMMA: they were suspended together with a piece of PMMA in a 40 tetrahydrofuran-60 ethanol (vol %) solution and ultrasonically agitated. The granules of <10 microm in size were impregnated at approximately 40-20 microm depth below the substrate surface. Two types were detected on the PMMA surface: (a) a glass-granule layer on PMMA, and (b) an inner granule layer, a PMMA layer, and an outer granule layer on the PMMA. The bioactivity of the implanted PMMA substrates was examined in vitro with a simulated body fluid (Kokubo solution). Apatite was precipitated on all glass granules and the whole substrate surfaces within 1 d. After 4 h soaking in the Kokubo solution, aggregates of apatite particles appeared on the substrate surface, independently of those on the glass granules, and they grew and proliferated on the whole subtrate surface in 7 d. Silica gel islands on PMMA due to the silicate anions from the glass were considered to induce nucleation of the apatite particles.

19.
J Mater Sci Mater Med ; 8(3): 157-61, 1997 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15348769

RESUMO

Bioactivity was investigated for several organically modified silicates (Ormosils) prepared through sol-gel processes. Ca(II)-free samples were biocompatible only, but Ca(II)containing samples were bioactive and deposited apatite during immersion in a simulated body fluid. The ease of silanol (Si-OH) group formation on the ormosils was considered a predominant factor controlling the bioactivity, while the effect of dissolved Ca(II) ions to increase the degree of supersaturation in the simulated body fluid is secondary.

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