RESUMEN
BACKGROUND/AIM: The incidence of chemotherapy-related adverse events in colorectal cancer patients with renal insufficiency has been compared to patients with normal renal function in only a few studies. The purpose of this analysis was to verify the feasibility and safety of adjuvant chemotherapy for postoperative colorectal cancer patients with renal insufficiency. PATIENTS AND METHODS: Adverse events and discontinuation of adjuvant chemotherapy for patients with curatively resected locally advanced colorectal cancer were examined using a combined database of individual patient data obtained from five large-scale clinical trials (n=4,106). The renal function of patients was classified into Level (L) 1-2: ≥60 ml/min and L3-4: <60 ml/min. RESULTS: As Grade 3 adverse events, hematological toxicities, such as neutropenia and anemia, and gastrointestinal disorders, such as diarrhea and vomiting, were significantly more frequent in the L3-4 group. Moreover, the time-to-treatment discontinuation in the L3-4 group was higher (hazard ratio=1.21, p=0.0012). T factor, N factor, and creatinine clearance level were found to be independent risk factors for the discontinuation of adjuvant chemotherapy. In the subgroup analysis of FOLFOX, neutropenia and diarrhea were significantly common in the L3-4 group, but neurotoxicities were not different. There was no significant difference in the discontinuation of adjuvant FOLFOX. CONCLUSION: Adverse events of adjuvant chemotherapy in patients with resected colorectal cancer were associated with renal insufficiencies. Since adverse events have the potential to shorten the duration of treatment, especially when using chemotherapy without oxaliplatin, careful management, including dose reduction, may be important in patients with renal insufficiency.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica , Quimioterapia Adyuvante , Neoplasias Colorrectales , Oxaliplatino , Insuficiencia Renal , Humanos , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Quimioterapia Adyuvante/efectos adversos , Neoplasias Colorrectales/complicaciones , Neoplasias Colorrectales/tratamiento farmacológico , Neoplasias Colorrectales/cirugía , Pueblos del Este de Asia , Estudios de Factibilidad , Fluorouracilo/administración & dosificación , Fluorouracilo/efectos adversos , Fluorouracilo/uso terapéutico , Leucovorina/administración & dosificación , Leucovorina/efectos adversos , Leucovorina/uso terapéutico , Neutropenia/inducido químicamente , Insuficiencia Renal/complicaciones , Resultado del Tratamiento , Oxaliplatino/administración & dosificación , Oxaliplatino/efectos adversos , Oxaliplatino/uso terapéuticoRESUMEN
Rheumatoid arthritis is an inflammatory autoimmune disease, characterized by autoantibody production, synovial inflammation, and joint destruction. Its pathogenesis is due to environmental factors and genetic backgrounds. Bruton's tyrosine kinase is a cytoplasmic non-receptor tyrosine kinase, expressed in most hematopoietic cell lineages, except T cells and plasma cells, and regulates various immune-related signaling pathways, thereby playing a crucial role in pathogenesis. Thus, inhibiting Bruton's tyrosine kinase may prove beneficial in treating autoimmune diseases. In the present study, we characterized Bruton's tyrosine kinase inhibitor, TAS5315, in vitro and evaluated its therapeutic effects in experimental arthritis models. TAS5315 markedly inhibited Bruton's tyrosine kinase enzyme activity and suppressed the B-cell receptor signaling pathway in Ramos cells. Moreover, it suppressed the expression of CD69, CD86, and MHC class II in mouse B lymphocytes and the production of TNF-α and MIP-1α in mouse macrophages and decreased bone resorption activity in mouse osteoclasts. Furthermore, it ameliorated the pathological changes in two rodent models of collagen-induced arthritis in vivo. TAS5315 improved bone mineral density and bone intensity. Thus, these results suggest that TAS5315 could be a promising therapeutic option for the treatment of rheumatoid arthritis.
Asunto(s)
Artritis Experimental , Artritis Reumatoide , Ratones , Animales , Artritis Experimental/patología , Agammaglobulinemia Tirosina Quinasa , Roedores , Inflamación/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/uso terapéuticoRESUMEN
PURPOSE: Although adjuvant chemotherapy (AC) using fluoro-pyrimidine and oxaliplatin (FU + oxaliplatin) is recommended after curative resection for locally advanced colon cancer patients, several randomized controlled trials have shown no additional effect of oxaliplatin in patients aged ≥ 70 years. Here, we examined the effectiveness of FU + oxaliplatin on the long-term outcome of old patients with a high risk of recurrence. METHODS: This multicenter, retrospective study included 346 colon cancer patients diagnosed with pathological T4 and/or N2 disease from 2016 to 2020. They were divided into an old group (≥ 70 years, n = 197) and a young group (< 70 years, n = 167). Propensity score matching was used to minimize selection bias, and 126 patients per group were matched. RESULTS: Before matching, the rates of poor performance status (p < 0.001) and the presence of comorbidities (76.1% vs. 47.9%, p < 0.001) were higher in the old group. Although all baseline factors were similar between groups, after matching, the AC rate was lower in the old group (45.2% vs. 65.1%, p = 0.002). In the old group, relapse-free (82.2% vs. 55.6% and 69.6%, p < 0.05) and overall survival (83.1% vs. 80.0% and 44.4%, p < 0.05) rates were significantly higher in the AC patients with FU + oxaliplatin than in the AC patients with only FU and the non-AC patients. CONCLUSION: The selected old colon cancer patients with a high risk of recurrence gained an additional benefit with respect to prognosis from FU + oxaliplatin as AC.
Asunto(s)
Neoplasias del Colon , Fluorouracilo , Anciano , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Quimioterapia Adyuvante , Neoplasias del Colon/tratamiento farmacológico , Neoplasias del Colon/patología , Neoplasias del Colon/cirugía , Fluorouracilo/uso terapéutico , Humanos , Recurrencia Local de Neoplasia/patología , Estadificación de Neoplasias , Oxaliplatino/uso terapéutico , Puntaje de Propensión , Estudios RetrospectivosRESUMEN
OBJECTIVE: Recent studies have suggested that ninjin'yoeito (NYT), a traditional Japanese Kampo medicine, improves diminished motivation in humans and animals, rendering it a novel therapeutic option for impaired motivation. To better characterize the effect of NYT on motivation, we examined its effect on motivated behaviors in mice. METHODS: Mouse models of neurodegeneration-related apathy, in which striatal dopamine receptor type 2-expressing medium spiny neurons (D2-MSNs) were progressively damaged by diphtheria toxin expression, were chosen. RESULTS: The decrease in effort-based operant responding for rewards (sucrose pellets), indicative of the mouse's motivated behavior, in the affected mice was not suppressed by chronic treatment with NYT suspended in drinking water at 1% (w/v). Mice were then subjected to a sucrose preference test, wherein they freely chose to ingest tap water and a sucrose solution without being required to exert effort. The affected mice showed a decline in preference for sucrose over tap water, relative to nonaffected controls, indicating anhedonia-like traits. In contrast to the diminished operant behavior, the anhedonic behavior in the affected mice was prevented by the NYT administration. Furthermore, NYT did not affect the size of Drd2 mRNA disappearance in the striatum of affected mice, suggesting that the NYT effect was unrelated to DTA-mediated neurodegeneration. CONCLUSION: These results demonstrate that the beneficial effect of NYT on motivation is mediated, at least in part, through the potentiation of hedonic capacity by certain neuromodulatory pathways.
Asunto(s)
Anhedonia/efectos de los fármacos , Cuerpo Estriado/efectos de los fármacos , Medicamentos Herbarios Chinos/farmacología , Medicina Kampo/métodos , Motivación/efectos de los fármacos , Receptores de Dopamina D2/biosíntesis , Anhedonia/fisiología , Animales , Condicionamiento Operante/efectos de los fármacos , Condicionamiento Operante/fisiología , Cuerpo Estriado/metabolismo , Expresión Génica , Japón , Ratones , Ratones de la Cepa 129 , Ratones Endogámicos C57BL , Ratones Endogámicos CBA , Ratones Transgénicos , Motivación/fisiología , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Receptores de Dopamina D2/genéticaRESUMEN
Activated HER2 is a promising therapeutic target for various cancers. Although several reports have described HER2 inhibitors in development, no covalent-binding inhibitor selective for HER2 has been reported. Here, we report a novel compound TAS0728 that covalently binds to HER2 at C805 and selectively inhibits its kinase activity. Once TAS0728 bound to HER2 kinase, the inhibitory activity was not affected by a high ATP concentration. A kinome-wide biochemical panel and cellular assays established that TAS0728 possesses high specificity for HER2 over wild-type EGFR. Cellular pharmacodynamics assays using MCF10A cells engineered to express various mutated HER2 genes revealed that TAS0728 potently inhibited the phosphorylation of mutated HER2 and wild-type HER2. Furthermore, TAS0728 exhibited robust and sustained inhibition of the phosphorylation of HER2, HER3, and downstream effectors, thereby inducing apoptosis of HER2-amplified breast cancer cells and in tumor tissues of a xenograft model. TAS0728 induced tumor regression in mouse xenograft models bearing HER2 signal-dependent tumors and exhibited a survival benefit without any evident toxicity in a peritoneal dissemination mouse model bearing HER2-driven cancer cells. Taken together, our results demonstrated that TAS0728 may offer a promising therapeutic option with improved efficacy as compared with current HER2 inhibitors for HER2-activated cancers. Assessment of TAS0728 in ongoing clinical trials is awaited (NCT03410927).
Asunto(s)
Antineoplásicos/química , Antineoplásicos/farmacología , Evaluación Preclínica de Medicamentos/métodos , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/farmacología , Receptor ErbB-2/antagonistas & inhibidores , Receptor ErbB-2/química , Animales , Antineoplásicos/administración & dosificación , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Humanos , Espectrometría de Masas , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Ratones SCID , Fosforilación/efectos de los fármacos , Unión Proteica , Inhibidores de Proteínas Quinasas/administración & dosificación , Receptor ErbB-2/genética , Receptor ErbB-2/metabolismo , Receptor ErbB-3/antagonistas & inhibidores , Receptor ErbB-3/metabolismo , Proteínas Recombinantes , Transducción de Señal/efectos de los fármacos , Carga Tumoral/efectos de los fármacos , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
To understand brain circuits of cognitive behaviors under natural conditions, we developed techniques for imaging neuronal activities from large neuronal populations in the deep layer cortex of the naturally behaving common marmoset. Animals retrieved food pellets or climbed ladders as a miniature fluorescence microscope monitored hundreds of calcium indicator-expressing cortical neurons in the right primary motor cortex. This technique, which can be adapted to other brain regions, can deepen our understanding of brain circuits by facilitating longitudinal population analyses of neuronal representation associated with cognitive naturalistic behaviors and their pathophysiological processes.
Asunto(s)
Conducta Animal/fisiología , Calcio/metabolismo , Corteza Motora/fisiología , Neuronas/fisiología , Animales , HaplorrinosRESUMEN
Yokukansankachimpihange (YKSCH), a traditional Japanese medicine, is widely used for the amelioration of the behavioral and psychological symptoms of dementia with digestive dysfunction. Regardless of its successful use for digestive dysfunction, the effect of YKSCH on body weight was unknown. Furthermore, if YKSCH increased body weight, it might increase motivation according to Kampo medicine theory. Therefore, we investigated whether YKSCH had the potential to increase body weight and enhance motivation in mice. To address this, C57BL/6J mice were used to evaluate the long-term effect of YKSCH on body weight and food-incentive motivation. As part of the evaluation, we optimized an operant test for use over the long-term. We found that feeding mice YKSCH-containing chow increased body weight, but did not increase their motivation to food reward. We propose that YKSCH may be a good treatment option for preventing decrease in body weight in patients with dementia.
Asunto(s)
Peso Corporal/efectos de los fármacos , Medicamentos Herbarios Chinos/farmacología , Alimentos , Animales , Masculino , Ratones , Ratones Endogámicos C57BL , Motivación/efectos de los fármacos , RecompensaRESUMEN
Recent data has indicated that Zn can modulate serotonergic function through the 5-HT1A receptor (5-HT1AR); however, the exact mechanisms are unknown. In the present studies, radioligand binding assays and behavioural approaches were used to characterize the pharmacological profile of Zn at 5-HT1ARs in more detail. The influence of Zn on agonist binding to 5-HT1ARs stably expressed in HEK293 cells was investigated by in vitro radioligand binding methods using the agonist [3H]-8-OH-DPAT. The in vivo effects of Zn were compared with those of 8-OH-DPAT in hypothermia, lower lip retraction (LLR), 5-HT behavioural syndrome and the forced swim (FST) tests. In the in vitro studies, biphasic effects, which involved allosteric potentiation of agonist binding at sub-micromolar Zn concentrations and inhibition at sub-millimolar Zn concentrations, were found. The in vivo studies showed that Zn did not induce LLR or elements of 5-HT behavioural syndrome but blocked such effects induced by 8-OH-DPAT. Zn decreased body temperature in rats and mice; however, Zn failed to induce hypothermia in the 5-HT1A autoreceptor knockout mice. In the FST, Zn potentiated the effect of 8-OH-DPAT. However, in the FST performed with the 5-HT1A autoreceptor knockout mice, the anti-immobility effect of Zn was partially blocked. Both the binding and behavioural studies suggest a concentration-dependent dual mechanism of Zn action at 5-HT1ARs, with potentiation at low dose and inhibition at high dose. Moreover, the in vivo studies indicate that Zn can modulate both presynaptic and postsynaptic 5-HT1ARs; however, Zn's effects at presynaptic receptors seem to be more potent.
Asunto(s)
Receptor de Serotonina 5-HT1A/metabolismo , Zinc/farmacología , 8-Hidroxi-2-(di-n-propilamino)tetralin , Animales , Conducta Animal , Temperatura Corporal/efectos de los fármacos , Células HEK293 , Humanos , Inmovilización , Cinética , Ratones Noqueados , Ratas Sprague-DawleyRESUMEN
One of the challenges to develop time-resolved fluorescence resonance energy transfer (TR-FRET) assay for serine/threonine (Ser/Thr) protein kinase is to select an optimal peptide substrate and a specific phosphor Ser/Thr antibody. This report describes a multiplexed random screen-based development of TR-FRET assay for ultra-high-throughput screening (uHTS) of small molecule inhibitors for a potent cancer drug target polo-like kinase 1 (Plk1). A screen of a diverse peptide library in a 384-well plate format identified several highly potent substrates that share the consensus motif for phosphorylation by Plk1. Their potencies were comparable to FKD peptide, a designed peptide substrate derived from well-described Plk1 substrate Cdc25C. A specific anti-phosphor Ser/Thr antibody p(S/T)F antibody that detects the phosphorylation of FKD peptide was screened out of 87 antibodies with time-resolved fluorometry technology in a 96-well plate format. Using FKD peptide and p(S/T)F antibody, we successfully developed a robust TR-FRET assay in 384-well plate format, and further miniaturized this assay to 1,536-well plate format to perform uHTS. We screened about 1.2 million compounds for Plk1 inhibitors using a Plk1 deletion mutant that only has the kinase domain and subsequently screened the same compound library using a full-length active-mutant Plk1. These uHTSs identified a number of hit compounds, and some of them had selectivity to either the deletion mutant or the full-length protein. Our results prove that a combination of random screen for substrate peptide and phospho-specific antibodies is very powerful strategy to develop TR-FRET assays for protein kinases.
Asunto(s)
Proteínas de Ciclo Celular/antagonistas & inhibidores , Evaluación Preclínica de Medicamentos/métodos , Biblioteca de Péptidos , Proteínas Serina-Treonina Quinasas/antagonistas & inhibidores , Proteínas Proto-Oncogénicas/antagonistas & inhibidores , Secuencia de Aminoácidos , Proteínas de Ciclo Celular/química , Transferencia Resonante de Energía de Fluorescencia , Humanos , Datos de Secuencia Molecular , Fosforilación , Proteínas Serina-Treonina Quinasas/química , Proteínas Proto-Oncogénicas/química , Quinasa Tipo Polo 1RESUMEN
Leptin inhibition of bone mass accrual requires the integrity of specific hypothalamic neurons but not expression of its receptor on these neurons. The same is true for its regulation of appetite and energy expenditure. This suggests that leptin acts elsewhere in the brain to achieve these three functions. We show here that brainstem-derived serotonin (BDS) favors bone mass accrual following its binding to Htr2c receptors on ventromedial hypothalamic neurons and appetite via Htr1a and 2b receptors on arcuate neurons. Leptin inhibits these functions and increases energy expenditure because it reduces serotonin synthesis and firing of serotonergic neurons. Accordingly, while abrogating BDS synthesis corrects the bone, appetite and energy expenditure phenotypes caused by leptin deficiency, inactivation of the leptin receptor in serotonergic neurons recapitulates them fully. This study modifies the map of leptin signaling in the brain and identifies a molecular basis for the common regulation of bone and energy metabolisms. For a video summary of this article, see the PaperFlick file with the Supplemental Data available online.
Asunto(s)
Apetito , Densidad Ósea , Metabolismo Energético , Leptina/metabolismo , Serotonina/metabolismo , Tronco Encefálico/metabolismo , Hipotálamo/metabolismo , Receptores de Leptina/metabolismo , Transducción de SeñalRESUMEN
BACKGROUND/AIMS: Recently, early detection of liver tumors has been possible with improvement of various imaging techniques, and practical selection of imaging is clinically necessary to distinguish metastatic liver carcinoma (MLC) from colorectal carcinoma. METHODOLOGY: We retrospectively examined the diagnostic accuracy of enhanced computed tomography (eCT) and super paramagnetic iron oxide particles magnetic resonance imaging (SPIO-MRI) for 110 MLC lesions in 47 patients who underwent hepatic resection at a single Japanese cancer institute between 2000 and 2006. Sensitivity and positive predictive value (PPV) of both imaging techniques in comparison with resected specimens were analyzed. Fourteen cases were synchronous liver metastasis, which were resected simultaneously. RESULTS: On a per patient basis, both eCT and SPIO-MRI showed a sensitivity of 85.1% (40 of 47 patients) and PPV was 100%, respectively. On a per lesion basis, a sensitivity of SPIO-MRI (98/110 lesions; 89%) tended to be higher than that of eCT (92 of 110 lesions; 84%), but not statistically different (p=0.32). PPV of SPIO-MRI (98 of 99 lesions; 99%) was not different from that of eCT (92 of 93; 99%). Twelve lesions in 7 patients that were not detected by both imaging methods were small lesions. PPV for liver cyst and non-timorous lesions was 99% by both imaging methods. Two liver cysts could be clearly diagnosed by SPIO-MRI only. CONCLUSIONS: We found no superiority of diagnosis with SPIO-MRI, which may not be conceptually useful for preoperative screening for MLC from colorectal carcinomas. SPIO-MRI may be useful to detect non-cancerous lesions as an adjuvant diagnostic tool with eCT.
Asunto(s)
Neoplasias Colorrectales/patología , Compuestos Férricos , Neoplasias Hepáticas/diagnóstico , Neoplasias Hepáticas/secundario , Imagen por Resonancia Magnética/métodos , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Tomografía Computarizada por Rayos XRESUMEN
BACKGROUND: The wear rate of polyethylene against alumina was demonstrated to be lower than against metal, and the results of early clinical studies of alumina-on-polyethylene combination were as good as expected, but the long-term results of alumina ceramic heads were not as good, as reported by several authors. The purpose of this study was to assess the clinical results over 10 years of cemented total hip arthroplasty (THA) with two types of alumina head: old and current alumina. METHODS: We compared the clinical results of these two types of alumina used for cemented THA. The first type was old alumina (containing 7% yttria), and 77 hips with a 28-mm head (group I) were included. The second type was current alumina (highly purified alumina), and 50 hips with a 26-mm head (group II) and 88 hips with a 22-mm head (group III) were included. The mean follow-up was 17 years 4 months in group I, 12 years 3 months in group II, and 10 years in group III. RESULTS: The Kaplan-Meier survival analysis, with revision for any reason as the endpoint, predicted 10-year survival rates of 90.8%, 100%, and 97.5% for groups I, II, and III, respectively. The survival curves differed significantly only between groups I and II. The probabilities of 10-year survival of the pros-theses with radiological loosening as the endpoint were 77.2%, 91.6%, and 96.5%, respectively. The survival curves showed significant differences only between groups II and III. CONCLUSIONS: The old alumina showed a higher wear rate and rougher surface on the femoral head than did the current alumina in our previous study. The clinical results also indicated superiority of current alumina over old alumina. The difference in the size of the femoral head (26 vs. 22 mm) did not affect the clinical results.
Asunto(s)
Óxido de Aluminio , Artroplastia de Reemplazo de Cadera , Prótesis de Cadera , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Diseño de Prótesis , Falla de Prótesis , Estudios Retrospectivos , ItrioRESUMEN
We describe a case of pseudomyxoma peritonei (PMP) successfully managed with intraperitoneal hyperthermic chemoperfusion. This case is unique due to the concurrent presence of intraductal papillary mucinous neoplasm (IPMN) of the pancreas. The patient presented with abdominal fullness. Abdominal computed tomography revealed massive ascites, thickened peritoneum, and a cystic lesion of the pancreas. Cytological examination of ascitic fluid sample showed mucin-rich atypical cells. Endoscopic retrograde pancreatography revealed a cystic lesion with the defect probably due to mural nodule and mucin, communicating with the pancreatic duct. At exploratory laparotomy, massive ascites and multiple nodules were identified within the peritoneal cavity. No primary tumour, including mucinous neoplasm of the appendix, was found. Histopathological examination of the omentum showed mucinous adenocarcinoma in pools of mucoid material, consistent with PMP. The relation between PMP and IPMN of the pancreas was possible, but not conclusive. The patient received intraperitoneal perfusion of saline heated to 42 degrees C containing cisplatin, etoposide, and mitomycin C, followed by 24 courses of postoperative chemotherapy with gemcitabine. The patient remains in good general condition with no signs of progression of PMP for 2 years, but with a gradual and progressive enlargement of the pancreatic cystic lesion.
Asunto(s)
Adenocarcinoma Mucinoso/patología , Adenocarcinoma Papilar/patología , Carcinoma Ductal Pancreático/patología , Neoplasias Pancreáticas/patología , Neoplasias Peritoneales/patología , Seudomixoma Peritoneal/patología , Adenocarcinoma Mucinoso/terapia , Adenocarcinoma Papilar/terapia , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Ascitis/patología , Carcinoma Ductal Pancreático/terapia , Quimioterapia del Cáncer por Perfusión Regional , Cisplatino/administración & dosificación , Desoxicitidina/análogos & derivados , Etopósido/administración & dosificación , Humanos , Hipertermia Inducida , Infusiones Parenterales , Masculino , Persona de Mediana Edad , Mitomicina/administración & dosificación , Neoplasias Primarias Múltiples , Neoplasias Pancreáticas/terapia , Neoplasias Peritoneales/terapia , Seudomixoma Peritoneal/terapia , GemcitabinaRESUMEN
Recently zirconia/alumina composites have been examined by many researchers as the new generation of bearing materials in total joint replacements. In this study, the phase stability of a Ce-TZP/Al(2)O(3) nanocomposite and conventional Y-TZP after aging, and its influence on wear resistance, were investigated. Very slight phase transformation was observed in both types of ceramics 18 months after the implantation of Ce-TZP/Al(2)O(3) or Y-TZP samples into rabbit tibiae. However, Y-TZP showed marked phase transformation (approximately 80%) after aging in an autoclave (121 degrees C) for 190 h or in physiological saline at 62 degrees C for 18 months, whereas the new composite remained almost resistant to degradation. According to the results of self-pairing pin-on-disk wear tests using ceramic specimens with or without autoclave aging, the wear factor was almost the same between Ce-TZP/Al(2)O(3) samples with and without aging (6.74 +/- 0.36 x 10(-8) and 6.04 +/- 0.95 x 10(-8) mm(3)/Nm, respectively). In contrast, although non-aged Y-TZP had the lowest wear factor (4.88 +/- 0.51 x 10(-8) mm(3)/Nm) of all specimens tested, aged Y-TZP showed 10-fold greater wear than nonaged Y-TZP. The present study suggests that Ce-TZP/Al(2)O(3) nanocomposite has much greater phase stability than Y-TZP, and that its wear properties are not influenced by aging.
Asunto(s)
Óxido de Aluminio , Materiales Biocompatibles , Cerio , Circonio , Calor , Microscopía Electrónica de Rastreo , Presión , Factores de TiempoRESUMEN
The objectives of this study were to investigate the biocompatibility, phase stability, and wear properties of a newly developed Ce-TZP/Al(2)O(3) nanocomposite, as compared to conventional ceramics, and to determine whether the new composite could be used as a bearing material in total joint prostheses. In tests of mechanical properties, this composite showed significantly higher toughness than conventional Y-TZP. For biocompatibility tests, cylindrical specimens of both the Ce-TZP/Al(2)O(3) nanocomposite and monolithic alumina were implanted into the paraspinal muscles of male Wistar rats. The tissue reactions were almost the same, and at 24 weeks after implantation, thin fibrous capsules with almost no inflammation were observed around both of them. There were no significant differences in membrane thickness between the two ceramics. After hydrothermal treatment in 121 degrees C vapor for 18 h, the new composite showed complete resistance to aging degradation, whereas Y-TZP showed a phase transformation of 25.3 vol% (initial 0.4%) to the monoclinic form. According to the results of pin-on-disk tests, the wear rates of Ce-TZP/Al(2)O(3) nanocomposite and alumina were 0.55 +/- 0.04 x 10(-7) and 2.12 +/- 0.37 x 10(-7)mm(3)/Nm, respectively. The results of this study suggest that the Ce-TZP/Al(2)O(3) nanocomposite is a promising alternative ceramic component for total joint replacement.
Asunto(s)
Resinas Compuestas/química , Prótesis Articulares/normas , Ensayo de Materiales , Óxido de Aluminio/administración & dosificación , Óxido de Aluminio/farmacología , Animales , Materiales Biocompatibles/administración & dosificación , Materiales Biocompatibles/farmacología , Materiales Biocompatibles/normas , Adhesión Celular , Cerio/administración & dosificación , Cerio/farmacología , Resinas Compuestas/administración & dosificación , Resinas Compuestas/farmacología , Masculino , Mecánica , Músculos/citología , Músculos/inmunología , Implantación de Prótesis , Ratas , Ratas Wistar , Circonio/administración & dosificación , Circonio/farmacologíaRESUMEN
Induction of an apatite-forming ability on a nano-composite of a ceria-stabilized tetragonal zirconia polycrystals (Ce-TZP) and alumina (Al2O3) polycrystals via chemical treatment with aqueous solutions of H3PO4, H2SO4, HCl, or NaOH has been investigated. The Ce-TZP/Al2O3 composite is attractive as a load-bearing bone substitute because of its mechanical properties. The chemical treatments produced Zr-OH surface functional groups, which are known to be effective for apatite nucleation in a body environment. The composite, after chemical treatment, was shown to form a bonelike apatite layer when immersed in a simulated body fluid containing ion concentrations nearly equal to those in human blood plasma. This implies that it may form apatite in the living body and bond to living bone through the apatite layer. This type of bioactive Ce-TZP/Al2O3 composite is therefore expected to be useful as a bone substitute, even under load-bearing conditions.