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1.
Anticancer Res ; 28(3B): 1805-12, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18630464

RESUMEN

UNLABELLED: THE AIM of the study was to evaluate time-to-progression (TTP) of rectal cancer in a group of patients receiving adjuvant chemotherapy (CHT) after combined neoadjuvant treatment. A secondary end-point was to identify the possible influence of clinical TNM (cTNM) or pathological TNM (pTNM) on TTP and overall survival (OS). PATIENTS AND METHODS: From January 2000 to December 2005, 101 consecutive rectal cancer patients who had been neoadjuvantly treated and had underne adjuvant CHT were retrospectively examined. The variables considered were age, gender and clinical and pathological effect of CHT administration. RESULTS: The mean age was 59 years (29-78 years) and the male:female ratio, 61:40. Forty-two patients had a lower (< or =5 cm from the anal verge), 54 a middle (from 6 to 10 cm) and 5 a higher (=10 cm) rectal lesion. All the patients had received the full course of neoadjuvant radiotherapy (RT) while 26.7% patients had received a reduced number of neoadjuvant CHT cycles. All the patients had undergone surgery and had received adjuvant chemotherapy which was completed in only 77.2% of the cases. Tumour down-staging and complete remissions were reported in 75.2% and 14.8% of cases, respectively. TTP and OS at 3 years were 81.2% and 91.1%, respectively. Out of locally recurrent patients, 77.8% were N+ (p=0.0026) at the pathological evaluation. CONCLUSION: In our series, neither administration of oxaliplatin-based adjuvant chemotherapy (p=0.44) nor age > or =70 years (p=0.51), clinical stage III (p=0.67), tumour down-staging (p=0.44) and achievement of pCR (p=0.66) appeared to have a significant impact on TTP; only pN+ (patients "not responders" to a neoadjuvant CHT-RT) influenced local relapse requiring more accurate postoperative treatment and confirming the literature data about the utility of adjuvant therapy in stage III disease.


Asunto(s)
Antimetabolitos Antineoplásicos/uso terapéutico , Desoxicitidina/análogos & derivados , Fluorouracilo/análogos & derivados , Fluorouracilo/uso terapéutico , Neoplasias del Recto/tratamiento farmacológico , Adulto , Anciano , Capecitabina , Quimioterapia Adyuvante , Desoxicitidina/uso terapéutico , Supervivencia sin Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Terapia Neoadyuvante , Estadificación de Neoplasias , Radioterapia Adyuvante , Neoplasias del Recto/patología , Neoplasias del Recto/radioterapia , Neoplasias del Recto/cirugía , Estudios Retrospectivos
2.
Anticancer Res ; 28(6B): 4095-100, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-19192666

RESUMEN

BACKGROUND: Neoadjuvant chemoradiotherapy (CT-RT) with continuous infusion (c.i.) 5-fluorouracil (5-FU) before resection of high-risk rectal cancer improves overall survival (OS) and pelvic control. Since the presence of cardiomiopathy may contraindicate c.i. of 5-FU, an alternative regimen of 5-FU CT-RT was prospectively studied in these patients. PATIENTS AND METHODS: From October 2000 to December 2006, patients with clinical stage T3 or T4, or node-positive disease were assigned according to their cardiological status to receive weekly 5-FU bolus administration during radiotherapy (RT). The preoperative treatment consisted of 5,040 cGy, delivered infractions of 180 cGy per day, five days per week, and 5-FU, given in 15 minutes at a dose of 450 mg/m2 of body surface area weekly during all radiotherapy. Surgery was performed six weeks after the completion of CT-RT. The primary endpoint was disease-free survival (DFS). RESULTS: Fifty-one patients received preoperative CH-RT. The 2-year OS rate was 92.3% and the 3-year DFS was 87.5%. The five-year cumulative incidence of local relapse was 3.9%. Grade 3 acute toxic effects occurred in 19.6% of the patients; worsening of patient's cardiopathy was never reported. CONCLUSION: Patients with cardiopathy developed similar local control and DFS, toxicity and OS with 5-FU administered weekly by bolus as those reported by literature data.


Asunto(s)
Antimetabolitos Antineoplásicos/administración & dosificación , Fluorouracilo/administración & dosificación , Neoplasias del Recto/tratamiento farmacológico , Neoplasias del Recto/radioterapia , Anciano , Anciano de 80 o más Años , Antimetabolitos Antineoplásicos/efectos adversos , Cardiomiopatías/complicaciones , Quimioterapia Adyuvante , Supervivencia sin Enfermedad , Femenino , Fluorouracilo/efectos adversos , Humanos , Inyecciones Intravenosas , Masculino , Terapia Neoadyuvante , Radioterapia Adyuvante , Neoplasias del Recto/complicaciones , Neoplasias del Recto/cirugía
3.
Anticancer Res ; 28(6B): 4129-35, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-19192672

RESUMEN

BACKGROUND: The aim of the study was to evaluate the pathological response (pTNM), local relapse and overall survival (OS) in clinical T3N0M0 (cT3N0M0) rectal cancer after a neoadjuvant chemoradiotherapy (CHT-RT) with 5-fluorouracil (5-FU) continuous infusion (c.i.) (+/- oxaliplatin) or bolus or capecitabine (an oral fluorpyrimidine). A secondary endpoint was to identify the local relapse rate and OS in those patients also receiving an adjuvant chemotherapy. PATIENTS AND METHODS: From January 2000 to January 2006, 48 consecutive cT3N0M0 rectal cancer cases neoadjuvantly treated were retrospectively examined. Variables considered were age, gender, modality of 5-FU administration and tumour site. RESULTS: Median age was 64 years (range, 22-84 years) and the male:female ratio was 28:20. All the patients received the full course of CHT-RT. Twenty-eight patients received c.i. 5-FU neoadjuvant chemotherapy, 17 received bolus 5-FU administration and 3 patients received capecitabine-based therapy. The mean number of chemotherapy weeks was 4.9 (range, 2-6). A total of 85.4% of patients were operated on without relevant postoperative complications but another 4 are awaiting surgery. Twenty-one patients had a lower (< or = 5 cm from the anal verge) and 27 had a middle rectal lesion (from 6 to 10 cm). In those patients with the lower site of lesion, a sphincter-saving (SS) procedure was achieved in 88.9%. Downstaging was reported in 66.7%. Ninety percent of cases are still free from progression after a median follow-up of 22.1 months; 7.5% are dead. CONCLUSION: The down-staging, the good level of SS and the disease-free survival (DFS) obtained here suggests that a neoadjuvant therapy may also be useful for stage II rectal cancer at diagnosis. The use of a postoperative chemotherapy should probably be outlined better.


Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias del Recto/tratamiento farmacológico , Neoplasias del Recto/radioterapia , Adulto , Anciano , Anciano de 80 o más Años , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Capecitabina , Quimioterapia Adyuvante , Desoxicitidina/administración & dosificación , Desoxicitidina/efectos adversos , Desoxicitidina/análogos & derivados , Supervivencia sin Enfermedad , Femenino , Fluorouracilo/administración & dosificación , Fluorouracilo/efectos adversos , Fluorouracilo/análogos & derivados , Humanos , Masculino , Persona de Mediana Edad , Terapia Neoadyuvante , Estadificación de Neoplasias , Compuestos Organoplatinos/administración & dosificación , Compuestos Organoplatinos/efectos adversos , Oxaliplatino , Radioterapia Adyuvante , Neoplasias del Recto/patología , Adulto Joven
4.
Eur J Cancer ; 43(10): 1508-13, 2007 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-17292603

RESUMEN

The incidence of most types of cancer is age-dependent and progressive ageing is rapidly increasing the number of elderly people who need treatment for cancer. Elderly patients (older than 70 years) present particular characteristics that make the choice of the correct treatment more difficult; for this reason, these patients are often undertreated and largely underrepresented in cancer trials making the experimental evidence on this topic even weaker. Only relatively recently has Health-Related Quality of Life (HRQoL) begun to be considered as one of the hard end-points for clinical cancer research in the elderly. Treatment of elderly cancer patients represents a typical situation where its assessment is particularly useful because of the expected toxicity of treatment and several unresolved methodological problems (higher frequency of illiteracy, worse compliance with the questionnaires, concomitant diseases, use of instruments not validated in the aged population). The aim of this review is to underline the importance detected by the too small number of studies on elderly QoL evaluation and the need in future trials either to improve QoL assessment in this subcategory of patients undergoing treatment for cancer or not, or find specific assessment tools to do it.


Asunto(s)
Antineoplásicos/uso terapéutico , Neoplasias/psicología , Calidad de Vida , Anciano , Humanos , Neoplasias/tratamiento farmacológico , Encuestas y Cuestionarios
5.
Anticancer Res ; 27(2): 1079-85, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17465247

RESUMEN

BACKGROUND: Rectal cancer is commonly diagnosed at a precocious stage, but for patients presenting at diagnosis with stage IV disease the best treatment is still undefined. The purpose of this study was to review the feasibility and outcome of multimodality treatment of rectal cancer patients metastatic at diagnosis. PATIENTS AND METHODS: From January 2000 to December 2005, 40 patients with histologically proven stage IV rectal adenocarcinoma (< 12 cm from the anal verge) were examined. Variables considered were age (under or over 65 years), tumour grade, presence of peritoneal carcinomatosis, type of surgery (palliative versus resection). RESULTS: The median age was 61 years (range, 32-83) and 27 were male and 13 female. Seventeen patients with unresectable or potentially resectable metastatic disease received neoadjuvant chemoradiotherapy (CHT-RT) with 5-fluorouracil (5FU) (plus oxaliplatin in 11 cases), radical surgery was performed in almost half of the cases; only in two patients were metastases also resected. If the patient is a candidate for radical surgical resection, the primary tumour should initially be treated as in a patient without metastatic disease and subsequently the primary tumour and metastases should be treated surgically. If the metastases are unresectable, the treatment of the primary lesion, according to the patient's symptoms, should be by palliative CHT. It is still not determined whether RT should be reserved for the symptomatic cases as an alternative to local surgery. In five patients treated with neoadjuvant CHT alone, radical local surgery was performed in two cases. Eighteen symptomatic patients were resected primarily; all of them received a postoperative CHT but only five of them also received postoperative RT. Nevertheless, after a multimodality treatment (neoadjuvant CHT +/- RT) 22.5% achieved a response rate (RR) (one complete remission (CR) and eight partial remission (PR)). Considering that all except two of the patients were locally radically resected and two of them also underwent metastases surgery, the overall RR was 17.5% (four CR and three PR). All of the CR were disease-free and alive after a median follow-up of 19.3 months. Age > or = 65 years had no impact on overall survival (OS), but the presence of peritoneal carcinosis in five patients showed a trend towards diminished survival, although it was not statistically significant (p = 0.08). CONCLUSION: The best treatment on diagnosis of metastatic rectal cancer is a multimodality CHT-RT approach. New prospective studies should evaluate non cross-resistant regimens as additional therapy for those patients with a systemic residual disease after common CHT-RT.


Asunto(s)
Adenocarcinoma/terapia , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias del Recto/terapia , Adenocarcinoma/patología , Adulto , Anciano , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Camptotecina/administración & dosificación , Camptotecina/efectos adversos , Camptotecina/análogos & derivados , Terapia Combinada , Supervivencia sin Enfermedad , Femenino , Fluorouracilo/administración & dosificación , Fluorouracilo/efectos adversos , Humanos , Irinotecán , Masculino , Persona de Mediana Edad , Terapia Neoadyuvante , Estadificación de Neoplasias , Compuestos Organoplatinos/administración & dosificación , Compuestos Organoplatinos/efectos adversos , Oxaliplatino , Radioterapia/efectos adversos , Neoplasias del Recto/patología , Estudios Retrospectivos , Tasa de Supervivencia
6.
Drugs Aging ; 24(9): 781-90, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17727307

RESUMEN

BACKGROUND: To evaluate the toxicity and feasibility of pelvic radiotherapy (RT) and/or surgery in elderly patients with locally advanced low-lying rectal cancer. PATIENTS AND METHODS: From November 1999 to November 2005, 51 patients aged >or=70 years who underwent RT for locally advanced low-lying rectal cancer were retrospectively examined. Variables considered were age, co-morbidities (evaluated according to the Charlson score and the Cumulative Illness Rating Scale-Geriatric [CIRS-G] score) and surgery versus no surgery. RESULTS: The median age was 80 years (range 70-94 years) and the male : female ratio was 33 : 18. A total of 5.9% of patients were considered 'fit', 72.5% had one or more CIRS-G grade 1 or 2 co-morbidities and 21.6% had one or more CIRS-G grade 3 co-morbidities. 54.9% of patients underwent surgery and 45.1% underwent RT. Only 9 of 21 (42.8%) patients who underwent radical resection received the full course of adjuvant RT and only seven (50%) of all patients treated with RT alone received the full dose of therapy. Patients with one or more CIRS-G grade 3 co-morbidities reported similar numbers of grade 1-2 toxicities as patients with one or more CIRS-G grade 2 co-morbidities. CONCLUSION: Notwithstanding the small number of patients analysed, the findings of this study indicate that elderly patients with rectal cancer and mild co-morbidities could probably receive the same treatment as fit elderly patients, given that tolerability appeared to be similar in both categories of patients. Neither age nor co-morbidities should be considered reasons to deny the patient the possible benefits of receiving complete treatment. Moreover, Multidimensional Geriatric Assessment should always be undertaken to help clinicians make better decisions about treatment. Further prospective trials are needed to confirm these results.


Asunto(s)
Neoplasias del Recto/radioterapia , Neoplasias del Recto/cirugía , Factores de Edad , Anciano , Anciano de 80 o más Años , Comorbilidad , Femenino , Evaluación Geriátrica , Humanos , Masculino , Recurrencia Local de Neoplasia , Cooperación del Paciente , Selección de Paciente , Radioterapia/efectos adversos , Neoplasias del Recto/mortalidad , Estudios Retrospectivos , Procedimientos Quirúrgicos Operativos/efectos adversos , Tasa de Supervivencia , Resultado del Tratamiento
7.
Cell Calcium ; 39(6): 539-50, 2006 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-16620965

RESUMEN

Presenilin-1 and -2 (PS1 and PS2) mutations, the major cause of familial Alzheimer's disease (FAD), have been causally implicated in the pathogenesis of neuronal cell death through a perturbation of cellular Ca(2+) homeostasis. We have recently shown that, at variance with previous suggestions obtained in cells expressing other FAD-linked PS mutations, PS2-M239I and PS2-T122R cause a reduction and not an increase in cytosolic Ca(2+) rises induced by Ca(2+) release from stores. In this contribution we have used different cell models: human fibroblasts from controls and FAD patients, cell lines (SH-SY5Y, HeLa, HEK293, MEFs) and rat primary neurons expressing a number of PS mutations, e.g. P117L, M146L, L286V, and A246E in PS1 and M239I, T122R, and N141I in PS2. The effects of FAD-linked PS mutations on cytosolic Ca(2+) changes have been monitored either by using fura-2 or recombinant cytosolic aequorin as the probe. Independently of the cell model or the employed probe, the cytosolic Ca(2+) increases, caused by agonist stimulation or full store depletion by drug treatment, were reduced or unchanged in cells expressing the PS mutations. Using aequorins, targeted to the endoplasmic reticulum or the Golgi apparatus, we here show that FAD-linked PS mutants lower the Ca(2+) content of intracellular stores. The phenomenon was most prominent in cells expressing PS2 mutants, and was observed also in cells expressing the non-pathogenic, "loss-of-function" PS2-D366A mutation. Taken as a whole, our findings, while confirming the capability of presenilins to modify Ca(2+) homeostasis, suggest a re-evaluation of the "Ca(2+) overload" hypothesis in AD and a new working hypothesis is presented.


Asunto(s)
Enfermedad de Alzheimer/genética , Calcio/metabolismo , Retículo Endoplásmico/metabolismo , Aparato de Golgi/metabolismo , Mutación/genética , Presenilina-1/genética , Presenilina-2/genética , Adulto , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Animales , Células Cultivadas , Células Clonales , Citosol/metabolismo , Femenino , Células HeLa , Humanos , Masculino , Ratones , Persona de Mediana Edad , Neuronas/citología , Neuronas/metabolismo , Presenilina-1/deficiencia , Presenilina-2/deficiencia , Ratas
8.
Anticancer Res ; 26(5B): 3973-81, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-17094429

RESUMEN

Monoclonal antibodies are a new class of agents targeting at specific receptors on cancer cells. In addition to having direct cellular effects, antibodies can cany substances, such as radioactive isotopes, toxins and antineoplastic agents, to the targeted cells. Two of them, cetuximab (Erbitux) and bevacizumab (Avastin), seem to have acquired a significant role in the management of patients with radically resected and advanced colorectal carcinoma. Cetuximab plus irinotecan has been approved as second-line therapy in irinotecan-resistant colorectal cancer patients; bevacizumab plus 5FU/LV has resulted in higher response and longer survival than 5FU/LV alone in first line metastatic colorectal cancer; its combination with oxaliplatin has recently doubled results. The superior therapeutic efficacy of these molecular targeting agents over traditional chemotherapy has been shown by the survival benefit achieved by patients with advanced or recurrent cancers. Although the precise molecular mechanism by which these agents produce or enhance an antitumour effect, alone or in combination with anticancer drugs, is unknown, the specific inhibition of target genes critically involved in tumour progression and metastasis is clear. Further studies to determine which patient groups and anticancer drugs are more appropriate for combination therapy with these agents are needed. All the most important data obtained through recent studies are discussed, emphasizing their mechanisms of action, safety profiles and clinical applications.


Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias Colorrectales/tratamiento farmacológico , Anticuerpos Monoclonales/administración & dosificación , Anticuerpos Monoclonales Humanizados , Bevacizumab , Camptotecina/administración & dosificación , Camptotecina/análogos & derivados , Fluorouracilo/administración & dosificación , Humanos , Irinotecán , Leucovorina/administración & dosificación
9.
Anticancer Res ; 26(6C): 4785-92, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-17214342

RESUMEN

A radical resection alone of colorectal hepatic metastases is possible in only 10-20% of the patients but, when resection and ablation are combined, the rate of radicalism can improve. A regional hepatic intra-arterial chemotherapy infusion (HAI) has been introduced in the clinical practice, as a possible alternative approach to systemic chemotherapy. Nevertheless, the introduction of new systemic therapies with monoclonal antibodies, combined to irinotecan or oxaliplatin, recently improved response rates and overall survival ia these patients. Aiming to evaluate a possible influence of HAI in these new treatments, the most important studies underlining the evolution of intrahepatic administration in recent years are reviewed.


Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/administración & dosificación , Neoplasias Colorrectales/patología , Neoplasias Hepáticas/tratamiento farmacológico , Neoplasias Hepáticas/secundario , Camptotecina/administración & dosificación , Camptotecina/análogos & derivados , Floxuridina/administración & dosificación , Fluorouracilo/administración & dosificación , Arteria Hepática , Humanos , Infusiones Intraarteriales , Irinotecán , Compuestos Organoplatinos/administración & dosificación , Oxaliplatino
10.
Biochim Biophys Acta ; 1658(3): 195-201, 2004 Oct 04.
Artículo en Inglés | MEDLINE | ID: mdl-15450957

RESUMEN

Glycyrrhetinic acid (GE), the aglycone of glycyrrhizic acid, a triterpene glycoside which represents one of the main constituents of licorice root, induces an oxidative stress in liver mitochondria responsible for the induction of membrane permeability transition. In fact, GE, by interacting with the mitochondrial respiratory chain, generates hydrogen peroxide which in turn oxidizes critical thiol groups and endogenous pyridine nucleotides leading to the opening of the transition pore. Most likely the reactive group of GE is the carbonyl oxygen in C-11 which, by interacting mainly with a Fe/S centre of mitochondrial complex I, generates an oxygen-centered radical responsible for the pro-oxidant action.


Asunto(s)
Permeabilidad de la Membrana Celular/efectos de los fármacos , Ácido Glicirretínico/farmacología , Mitocondrias Hepáticas/efectos de los fármacos , Animales , Potenciales de la Membrana , Mitocondrias Hepáticas/fisiología , Ratas , Especies Reactivas de Oxígeno
11.
Biosens Bioelectron ; 45: 13-8, 2013 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-23454337

RESUMEN

A simple carbon paste (CP) electrode, modified with novel maghemite (γ-Fe2O3) nanoparticles, called SAMNs (surface active maghemite nanoparticles) and characterized by a mean diameter of about 10nm, has been developed. The electrode catalyzes the electro-reduction of hydrogen peroxide at low applied potentials (-0.1 V vs SCE). In order to improve the electrocatalytic properties of the modified electrode an ionic liquid, namely 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6), was introduced. At -0.1 V, the sensitivity of the SAMN-BMIM-PF6-CP electrode was 206.51 nA µM(-1)cm(-2), with a detection limit (S/N=3) of 0.8 µM, in the 0-1.5mM H2O2 concentration range. Furthermore, glucose oxidase was immobilized on the surface of maghemite nanoparticles as a monomolecular layer, by a bridge constituted of rhodamine B isothiocyanate, leading to a fluorescent, magnetic drivable nanocatalyst, containing 10 ± 2 enzyme molecules per nanoparticle. The resulting enzyme electrode presents a linear calibration curve toward glucose in solution in the concentration range of 0-1.5mM glucose, characterized by a sensitivity of 45.85 nA µM(-1)cm(-2) and a detection limit (S/N=3) of 0.9 µM. The storage stability of the system was evaluated and a half-life of 2 months was calculated, if the electrode is stored at 4°C in buffer. The present work demonstrates the feasibility of these surface active maghemite nanoparticles as efficient hydrogen peroxide electro-catalyst, which can be easily coupled to hydrogen peroxide producing enzymes in order to develop oxidase based reagentless biosensor devices.


Asunto(s)
Técnicas Biosensibles/métodos , Compuestos Férricos/química , Glucosa/aislamiento & purificación , Nanopartículas del Metal/química , Enzimas Inmovilizadas , Glucosa Oxidasa/química , Humanos , Peróxido de Hidrógeno/química , Líquidos Iónicos/química , Tamaño de la Partícula , Propiedades de Superficie
12.
Int J Nanomedicine ; 7: 2249-59, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22619559

RESUMEN

Novel superparamagnetic surface-active maghemite nanoparticles (SAMNs) characterized by a diameter of 10 ± 2 nm were modified with bovine serum amine oxidase, which used rhodamine B isothiocyanate (RITC) adduct as a fluorescent spacer-arm. A fluorescent and magnetically drivable adduct comprised of bovine serum copper-containing amine oxidase (SAMN-RITC-BSAO) that immobilized on the surface of specifically functionalized magnetic nanoparticles was developed. The multifunctional nanomaterial was characterized using transmission electron microscopy, infrared spectroscopy, mass spectrometry, and activity measurements. The results of this study demonstrated that bare magnetic nanoparticles form stable colloidal suspensions in aqueous solutions. The maximum binding capacity of bovine serum amine oxidase was approximately 6.4 mg g(-1) nanoparticles. The immobilization procedure reduced the catalytic activity of the native enzyme to 30% ± 10% and the Michaelis constant was increased by a factor of 2. We suggest that the SAMN-RITC-BSAO complex, characterized by a specific activity of 0.81 IU g(-1,) could be used in the presence of polyamines to create a fluorescent magnetically drivable H(2)O(2) and aldehydes-producing system. Selective tumor cell destruction is suggested as a potential future application of this system.


Asunto(s)
Amina Oxidasa (conteniendo Cobre)/administración & dosificación , Nanopartículas de Magnetita/química , Amina Oxidasa (conteniendo Cobre)/sangre , Amina Oxidasa (conteniendo Cobre)/genética , Secuencia de Aminoácidos , Animales , Bovinos , Materiales Biocompatibles Revestidos , Coloides , Colorantes Fluorescentes , Nanopartículas de Magnetita/ultraestructura , Datos de Secuencia Molecular , Nanomedicina , Rodaminas
13.
Acta Biomater ; 8(6): 2068-76, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22342825

RESUMEN

Superparamagnetic nanoparticles (20-40 nm) of maghemite, γ-Fe(2)O(3), with well-defined stoichiometric structure, are synthesized by the borohydride reduction of ferric chloride at an elevated temperature (100°C) followed by thermal treatment of the reaction product. Prepared maghemite nanoparticles reveal excellent colloidal stability for a long time without the necessity for any additional surface modification. These colloidal features are due to surface stabilizing OH(-) groups, which act as charge barriers preventing a particle aggregation and enabling a reversible binding of various oppositely charged organic substances. Such binding with rhodamine B isothiocyanate results in the fluorescent magnetic nanocarrier providing, at the same time, a spacer arm for covalent immobilization of other biosubstances including enzymes. In this work, we exploit this general applicability of the developed nanocarrier for covalent immobilization of glucose oxidase. This is the first reported example of magnetically drivable fluorescent nanocatalyst. The immobilized enzyme creates a 3-5 nm thick layer on the nanoparticle surface as proved by high-resolution transmission electron microscopy. This layer corresponds to 10 enzyme molecules, which are bound to the nanoparticle surface as found by the fluorimetric determination of flavin adenine dinucleotide. The developed magnetic fluorescent nanocatalyst, showing a rate constant of 32.7s(-1) toward glucose oxidation, can be used as a biosensor in various biochemical, biotechnological, and food chemistry applications. The presence of the nanocatalyst can be simply monitored by its fluorescence; moreover, it can be easily separated from the solution by an external magnetic field and repeatedly used without a loss of catalytic efficiency.


Asunto(s)
Técnicas Biosensibles , Radical Hidroxilo/química , Rodaminas/química , Fluorescencia , Magnetismo , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión , Espectroscopía de Mossbauer
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