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1.
Eur J Surg Oncol ; 50(6): 108342, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38636247

RESUMO

OBJECTIVE: The treatment of early-stage cervical cancer (CC) is primarily based on surgery. Adjuvant (chemo)radiotherapy can be necessary in presence of risk factors for relapse (tumor size, deep stromal invasion, lymphovascular space invasion (LVSI), positive margins, parametrial or lymph node involvement), increasing the risk of treatment toxicity. Preoperative brachytherapy can reduce tumor extension before surgery, potentially limiting the need for adjuvant radiotherapy. This study reports long-term clinical outcomes on efficacy and toxicity of preoperative pulse-dose-rate (PDR) brachytherapy in early-stage CC. METHODS: All patients treated at Institut Curie between 2007 and 2022 for early-stage CC by preoperative brachytherapy were included. A PDR technique was used. Patients underwent hysterectomy associated with nodal staging following brachytherapy. RESULTS: 73 patients were included. The median time from brachytherapy to surgery was 45 days [range: 25-78 days]. With a median follow-up of 51 months [range: 4-185], we reported 3 local (4 %), 1 locoregional (1 %) and 8 metastatic (11 %) relapses. At 10 years, OS was 84.1 % [95 % CI: 70.0-100], DFS 84.3 % [95 % CI:74.6-95.3] and LRFS 92.8 % [95 % CI:84.8-100]. Persistence of a tumor residue, observed in 32 patients (44 %), was a significant risk factor for metastatic relapse (p = 0.02) and was associated with the largest tumor size before brachytherapy (p = 0.04). Five patients (7 %) experienced grade 3 toxicity. One patient (1 %) developed grade 4 toxicity. Ten patients (14 %) received adjuvant radiotherapy, increasing the risk of lymphedema (HR 1.31, 95 % CI [1.11-1.54]; p = 0.002). CONCLUSIONS: PDR preoperative brachytherapy for early-stage cervical cancer provides high long-term tumor control rates with low toxicity.


Assuntos
Braquiterapia , Histerectomia , Estadiamento de Neoplasias , Neoplasias do Colo do Útero , Humanos , Feminino , Neoplasias do Colo do Útero/patologia , Neoplasias do Colo do Útero/radioterapia , Braquiterapia/métodos , Pessoa de Meia-Idade , Adulto , Idoso , Recidiva Local de Neoplasia , Resultado do Tratamento , Carcinoma de Células Escamosas/patologia , Carcinoma de Células Escamosas/radioterapia , Carcinoma de Células Escamosas/terapia , Estudos Retrospectivos , Radioterapia Adjuvante , Cuidados Pré-Operatórios/métodos , Taxa de Sobrevida , Intervalo Livre de Doença
2.
Gynecol Oncol ; 170: 309-316, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36758421

RESUMO

INTRODUCTION: The goal of this study was to compare the outcomes of preoperative brachytherapy followed by radical surgery versus radical surgery alone in cervical cancer with tumor between 2 and 4 cm (FIGO 2018 IB2). MATERIAL AND METHODS: SENTICOL I and SENTICOL II were two French prospective multicentric trials evaluating sentinel node biopsy in early-stage cervical cancer between 2005 and 2012. Preoperative brachytherapy (low-dose rate or pulse-dose rate at the dose of 60Gy) could be performed 6 to 8 weeks prior to the radical hysterectomy, at the discretion of each center. SENTICOL I and SENTICOL II cohorts were retrospectively analysed to compare the outcomes of preoperative brachytherapy or upfront surgery in patients with IB2 cervical tumor. RESULTS: A total of 104 patients were included: 55 underwent upfront radical hysterectomy and 49 underwent preoperative brachytherapy followed by radical hysterectomy. Patients with preoperative brachytherapy were more likely to have no residual disease (71.4% vs. 25.5%, p < 0.0001) and to be defined as low risk according to Sedlis criteria (83.3% vs. 51.2%, p < 0.0001). Adjuvant treatments were required less frequently in case of preoperative brachytherapy (14.3% vs. 54.5%, p < 0.0001). Patients with preoperative brachytherapy experienced more postoperative complications grade ≥ 3 (24.5% vs. 9.1%, p = 0.03). Patients with preoperative brachytherapy had better 5-year disease-free survival compared to patients who underwent surgery alone, 93.6% and 74.4% respectively (p = 0.04). CONCLUSION: Although preoperative brachytherapy was significantly associated with more severe postoperative complications, better pathologic features were obtained on surgical specimens and led to a better 5-year disease-free survival in IB2 cervical cancer.


Assuntos
Braquiterapia , Neoplasias do Colo do Útero , Feminino , Humanos , Braquiterapia/efeitos adversos , Neoplasias do Colo do Útero/patologia , Estudos Retrospectivos , Estudos Prospectivos , Estadiamento de Neoplasias , Histerectomia/efeitos adversos , Complicações Pós-Operatórias/etiologia
3.
Cancer Radiother ; 26(6-7): 899-904, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36030191

RESUMO

In 1998, an editorial from the International Journal of Radiation Oncology - Biology - Physics (IJROBP) on the occasion of the publication of Phase I by Zelefsky et al. on 3D radiotherapy dose escalation asked the question: "will more prove better?". More than 20 years later, several prospective studies have supported the authors' conclusions, making dose escalation a new standard in prostate cancer. The data from prospective randomized studies were ultimately disappointing in that they failed to show an overall survival benefit from dose escalation. However, there is a clear and consistent benefit in biochemical recurrence-free survival, which must be weighed on an individual patient basis against the potential additional toxicity of dose escalation. Techniques and concepts have become more and more precise, such as intensity modulated irradiation, simultaneous integrated boost, hypofractionated dose-escalation, pelvic irradiation with involved node boost or focal dose-escalation on gross recurrence after prostatectomy. The objective here was to summarize the prospective data on dose escalation in prostate cancer and in particular on recent advances in the field. In 2022, can we finally say that more has proven better?


Assuntos
Braquiterapia , Neoplasias da Próstata , Radioterapia de Intensidade Modulada , Braquiterapia/métodos , Humanos , Masculino , Estudos Prospectivos , Prostatectomia , Neoplasias da Próstata/tratamento farmacológico , Radioterapia de Intensidade Modulada/métodos , Ensaios Clínicos Controlados Aleatórios como Assunto
4.
Cancer Radiother ; 26(4): 542-546, 2022 Jun.
Artigo em Francês | MEDLINE | ID: mdl-34454837

RESUMO

PURPOSE: Moderate hypofractionated radiotherapy has become routine practice for a selected population of patients treated for early-stage breast cancer. In April 2020, the Fast Forward (FF) study was published which introduced another extreme hypofractionated radiotherapy regimen in five sessions over a week. The aim of this work is to evaluate the population of first patients in whom this regimen was used in our department, as well as the results in terms of early toxicity. MATERIAL AND METHODS: We retrospectively analysed all the patients treated in our department according to the Fast Forward protocol after establishing an institutional consensus regarding the selection of patients with breast cancer without indication for lymph node irradiation. All patients received breast-only irradiation at a total dose of 26Gy in five fractions according to protocol. All patients were treated by modern conformational techniques with planning large volume coverage between 95 and 100%. Acute toxicity of the treatment was assessed using the NCI CTC v4.0 scale and the general condition was assessed according to the WHO classification. RESULTS: Between August 2020 and May 2021, 30 patients were included, treated on the breast alone without complement on the tumour bed or irradiation of the lymph node areas. The median age of the patients was 80years (range: 60-85years) with performance status 2 in 27 cases (89%). Only one patient had metastatic disease (3%), one patient presented locally advanced and 28 (94%) patients had early stage disease. Three patients (10%) were treated in dorsal decubitus according to the "field in the field" technique and 27 patients (90%) in isocentric lateral decubitus, which made it possible to avoid the organs at risk such as the heart (average dose of less than 1Gy) and the lungs. The early toxicity observed was grade I radio dermatitis in 8 patients (27%). No grade 2 and 3 toxicity, as well as radiation-induced pain or lymphedema were observed. CONCLUSIONS: The results of this series of patients treated with hypofractionated radiotherapy according to the Fast Forward protocol on the breast alone with adapted techniques show that the protocol is feasible, with little early toxicity but a greater follow-up is necessary to assess long-term toxicity.


Assuntos
Neoplasias da Mama , Mama , Idoso , Idoso de 80 Anos ou mais , Mama/efeitos da radiação , Neoplasias da Mama/patologia , Feminino , Humanos , Mastectomia Segmentar , Pessoa de Meia-Idade , Seleção de Pacientes , Hipofracionamento da Dose de Radiação , Estudos Retrospectivos
5.
Respir Res ; 22(1): 319, 2021 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-34949190

RESUMO

BACKGROUND: Tidal expiratory flow limitation (EFLT) is common among COPD patients. Whether EFLT changes during sleep and can be abolished during home ventilation is not known. METHODS: COPD patients considered for noninvasive ventilation used a ventilator which measured within-breath reactance change at 5 Hz (∆Xrs) and adjusted EPAP settings to abolish EFLT. Participants flow limited (∆Xrs > 2.8) when supine underwent polysomnography (PSG) and were offered home ventilation for 2 weeks. The EPAP pressure that abolished EFLT was measured and compared to that during supine wakefulness. Ventilator adherence and subjective patient perceptions were obtained after home use. RESULTS: Of 26 patients with supine EFLT, 15 completed overnight PSG and 10 the home study. In single night and 2-week home studies, EFLT within and between participants was highly variable. This was unrelated to sleep stage or body position with only 14.6% of sleep time spent within 1 cmH2O of the awake screening pressure. Over 2 weeks, mean EPAP was almost half the mean maximum EPAP (11.7 vs 6.4 cmH2O respectively). Group mean ∆Xrs was ≤ 2.8 for 77.3% of their home use with a mean time to abolish new EFLT of 5.91 min. Adherence to the ventilator varied between 71 and 100% in prior NIV users and 36-100% for naïve users with most users rating therapy as comfortable. CONCLUSIONS: Tidal expiratory flow limitation varies significant during sleep in COPD patients. This can be controlled by auto-titrating the amount of EPAP delivered. This approach appears to be practical and well tolerated by patients. TRIAL REGISTRATION: The trial was retrospectively registered at CT.gov NCT04725500.


Assuntos
Expiração/fisiologia , Ventilação não Invasiva/métodos , Polissonografia/métodos , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Doença Pulmonar Obstrutiva Crônica/terapia , Volume de Ventilação Pulmonar/fisiologia , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doença Pulmonar Obstrutiva Crônica/diagnóstico , Estudos Retrospectivos
6.
Gynecol Oncol ; 158(2): 323-330, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32475773

RESUMO

OBJECTIVE: This study assessed outcomes of inoperable endometrial cancer (IEC) patients treated with definitive external beam radiation therapy (EBRT) followed by a 3D image-guided brachytherapy boost. METHODS: All consecutive patients treated with EBRT followed by 3D image-guided brachytherapy for IEC were retrospectively included. EBRT delivered a dose of 45Gy. Then, patients had an uterovaginal brachytherapy guided by 3D imaging. Clinical target volume (CTVBT) included the whole uterus and the initial disease extent. Gross tumour volume (GTVres) included the residual disease at time of brachytherapy. RESULTS: Twenty-seven patients were identified. Causes of inoperability were comorbidities (37%) or tumour loco regional extent (63%). Including EBRT and brachytherapy, the median D90 (minimal dose delivered to 90% of the volume) was 60.7 GyEQD2 (IQR = 56.4-64.2) for the CTVBT, and was 73.6 GyEQD2 (IQR = 64.1-83.7) for the GTVres. The median overall treatment time was 50 days (IQR = 46-54). The mean follow-up was 36.5 months (SD = 30.2). The cumulative incidence of local, pelvic and distant failures was 19% (n = 5), 7% (n = 2) and 26% (n = 7), respectively. Five-year overall survival was 63% (95% CI = 43-91). Late urinary and gastro intestinal toxicities ≥ grade 2 were reported in four (15%) and two patients (7%) respectively. No vaginal toxicity ≥ grade 2 was reported. CONCLUSIONS: EBRT followed by intracavitary brachytherapy seems to be an effective option for IEC. The implementation of 3D concepts at time of brachytherapy may contribute to high local control probability and low toxicity profile. Large scale retrospective or prospective data are needed to confirm these early data.


Assuntos
Braquiterapia/métodos , Neoplasias do Endométrio/diagnóstico por imagem , Neoplasias do Endométrio/radioterapia , Radioterapia Guiada por Imagem/métodos , Idoso , Estudos de Casos e Controles , Intervalo Livre de Doença , Neoplasias do Endométrio/patologia , Feminino , Humanos , Imageamento Tridimensional/métodos , Metástase Linfática , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Estudos Retrospectivos , Tomografia Computadorizada por Raios X
7.
Gynecol Oncol ; 157(3): 644-648, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32173045

RESUMO

INTRODUCTION: Since dose escalation allowed by image-guided adaptive brachytherapy (IGABT) in locally advanced cervical cancer (LACC), local relapses have become a rare event. Only scarce data are available on the outcome of patients experiencing a local relapse after IGABT. METHODS: Between 2004 and 2016, all consecutive patients treated at Gustave Roussy Institute for LACC and receiving concomitant chemoradiation and IGABT were analysed. Clinical and treatment-related prognostic factors for survival after local relapse were searched, in order to potentially identify patients requiring salvage treatment. RESULTS: Two hundred and fifty-nine patients were treated during this period. With a median follow-up of 4.1 years, 10.8% (n = 28) had a local relapse. Among these patients, 53.6% had synchronous lymph nodes or distant metastatic relapse and only 13 patients (5% of all patients) had isolated local relapse. After local relapse, median survival was 47 months and three patients were alive at last follow-up. Only three patients with local relapse could receive salvage surgery (10.7%). Metastases occurrence and pelvic wall involvement were the main contraindications (67.9%) for salvage surgery. Among the three patients treated with surgery, two are still alive at last follow-up without significant complication. Improved survival was observed among the two patients who could have surgery (p = .02). Local progression led to serious symptoms in 75% of patients. Only the time interval between brachytherapy and relapse (<1 year) was prognostic for 2-year overall survival (p = .005). CONCLUSION: Salvage surgery is feasible in a very low number of highly selected patients with local relapse following IGABT. Local failure is a major cause of severe local symptoms, confirming that every effort should be done to achieve long-term local control through dose escalation.


Assuntos
Braquiterapia/métodos , Quimiorradioterapia/métodos , Neoplasias do Colo do Útero/tratamento farmacológico , Neoplasias do Colo do Útero/radioterapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia , Neoplasias do Colo do Útero/diagnóstico por imagem , Adulto Jovem
8.
Cancer Treat Rev ; 84: 101976, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32006796

RESUMO

With population ageing, cancer treatments in elder patients is becoming a true public health care issue. There is an authentic dilemma between patient's frailty, residual life expectancy and the toll that take anticancer treatments. Since elder patients are almost always excluded from clinical trials, it is hard to get robust scientific data on the tolerability of oncologic treatments and to set in place recommendations. Cervix cancer is traditionally diagnosed in younger women but it has a 2nd incidence peak between 60 and 70 years old. Cervix cancer in elder patients is a subject to many questions in terms of screening and is a therapeutic challenge. This article reviews literature data on these different aspects, from screening to surgery, from radiotherapy to brachytherapy, from chemotherapy to supportive care, from immunotherapy to geriatric assessment. We tried to show how modern therapeutic innovations may benefit elder patients. Expected benefits in terms of efficacy and toxicity may overcome the long-lasting tendency to undertreatment in elder patients and improve their quality of life after cancer treatment. In 2020, there seems to be less and less reasons justifying that elder women with cervix cancer may not receive the appropriate treatment.


Assuntos
Avaliação Geriátrica/métodos , Qualidade de Vida , Neoplasias do Colo do Útero/terapia , Idoso , Terapia Combinada , Feminino , Humanos
9.
Gene Ther ; 10(9): 774-80, 2003 May.
Artigo em Inglês | MEDLINE | ID: mdl-12704416

RESUMO

Transfer of the sodium iodide symporter (hNIS) has been proposed as a new principle of cancer gene therapy. Using clinically relevant doses of (131)I for the treatment of NIS-expressing prostate carcinoma cells, we investigated the kinetics and the absorbed doses obtained in these tumors. hNIS-expressing cell lines accumulated up to 200 times more iodide when compared to wild-type cells. However, a rapid efflux of the radioactivity (80%) occurred during the first 20 min after replacement of the medium. In rats, the hNIS-expressing tumors accumulated up to 20 times more iodide when compared to contralateral transplanted wild-type tumors. After 24 h and doses of 550, 1200 or 2400 MBq/m(2) hNIS-expressing tumors lost 89, 89 and 91% of the initial activity, respectively. Dosimetric calculations showed that 1200 MBq/m(2) resulted in 3+/-0.5 Gy (wild-type tumor 0.15+/-0.1 Gy) and 2400 MBq/m(2) resulted in 3.1+/-0.9 Gy (wild-type tumor 0.26+/-0.02 Gy). Although transduction of the hNIS gene induces iodide transport in rat prostate adenocarcinoma a rapid efflux occurs, which leads to a low absorbed dose in genetically modified tumors. With regard to a therapeutic application additional conditions need to be defined leading to iodide trapping.


Assuntos
Adenocarcinoma/radioterapia , Terapia Genética/métodos , Iodetos/metabolismo , Radioisótopos do Iodo/uso terapêutico , Neoplasias da Próstata/radioterapia , Simportadores/genética , Absorção , Adenocarcinoma/metabolismo , Animais , Transporte Biológico , Vetores Genéticos/farmacologia , Humanos , Imuno-Histoquímica/métodos , Radioisótopos do Iodo/farmacocinética , Masculino , Neoplasias Experimentais , Neoplasias da Próstata/metabolismo , Ratos , Ratos Endogâmicos , Retroviridae/genética , Simportadores/análise , Transdução Genética/métodos , Células Tumorais Cultivadas
10.
Int J Radiat Biol ; 78(8): 721-32, 2002 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12194756

RESUMO

PURPOSE: There is evidence that the duration of the G2/M delay following irradiation is correlated with cell survival. We studied the radiosensitizing potential of pentoxifylline (PTX) and the PTX-mediated modulation of cell-cycle progression dependent on the p53 status of various human tumour cell lines. MATERIALS AND METHODS: The cellular radiosensitivity of human MCF-7 (wild-type p53) and HT-29 (p53-defective) tumour cells, which were exposed to PTX (2 mM) immediately after gamma-irradiation was determined by colony forming assay. The influence on cell cycle progression after irradiation (6 Gy) was assessed by flow cytometric analysis using p53 wild-type MCF-7 and HPR600 cells, and p53-defective HT-29 and WiDr cells. RESULTS: Clonogenic survival assays up to 8 Gy demonstrated that p53-defective HT-29 cells (sensitizer enhancement ratio [SER]=1.54) were sensitized by PTX (2 mM) to a significantly higher degree than p53 wild-type MCF-7 (SER=1.14) cells. Exposure of irradiated (6 Gy) cells to PTX (2 mM) resulted in abrogation of the radiation-induced G2/M arrest in the p53-defective HT-29 and WiDr cells, whereas the p53 wild-type-expressing MCF-7 and HPR600 cells showed less significant impairment of the G2/M checkpoint. In HT-29 cells, the rate of transition into mitosis was even higher than in the sham-treated control cells. G2/M abrogation was accompanied by an increase of apoptosis only in HPR600 cells. CONCLUSIONS: Since PTX was less effective in cells expressing intact p53, the application of PTX suggests a promising strategy of pharmacological disruption of the G2/M checkpoint control by which preferentially radiation-resistant tumours with defective p53 function might be rendered more sensitive to ionizing radiation.


Assuntos
Pentoxifilina/farmacologia , Protetores contra Radiação/farmacologia , Proteína Supressora de Tumor p53/genética , Ciclo Celular/efeitos dos fármacos , Sobrevivência Celular , Relação Dose-Resposta à Radiação , Citometria de Fluxo , Fase G2/efeitos da radiação , Humanos , Cinética , Mitose/efeitos da radiação , Tolerância a Radiação , Fatores de Tempo , Células Tumorais Cultivadas , Proteína Supressora de Tumor p53/metabolismo
11.
PDA J Pharm Sci Technol ; 55(3): 191-201, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11417110

RESUMO

To optimize polymer design for tumor directed drug delivery, the fate and the total body distribution of soluble synthetic macromolecules, derived from copolymers of [(N-2-(hydroxypropyl)methacrylamide] (HPMA) were monitored scintigraphically after radiolabeling with 131I during a seven day time window. Equimolar concentrations of radioiodinated copolymers of HPMA with small amounts of methacryloyltyrosinamide (pHPMA) differing in molecular weight (23.4 kD, 27.3 kD, 30.5 kD, 44 kD, 58.4 kD, 60.1 kD) were injected intravenously into Copenhagen rats bearing Dunning prostate carcinomas (subline R3327-AT1). Scintigraphic data were validated by determining absolute amounts of [131I]pHPMA in both tumor tissue and normal organs after sacrificing the animals. Copolymers were cleared from blood circulation in a molecular-weight dependent manner, either via excretion or by extravasation into normal and neoplastic tissues. While distribution patterns for pHPMAs in normal organs were quite similar, absolute amounts of copolymer uptake differed. The higher the molecular weight, the more radioactivity was taken up by the organs. Highest amounts of radioactivity were seen in the lung, liver, and spleen. In solid tumors, kinetics of pHPMA accumulation was clearly dependent on molecular weight. pHPMAs below the renal threshold peaked at 24 hours p.i. and then remained constant. In contrast, copolymers above the renal clearance threshold displayed a continuous accumulation reaching a significantly higher tumor uptake, presumably due to the very small or non existent polymer release from tumor tissue. Absolute amounts of tumor uptake determined by dissection analysis were 0.5 +/- 0.1% of injected dose/g tissue for the 27.3 kD pHPMA and 1.2 +/- 0.1% for the 60.1 kD pHPMA, respectively. In conclusion, our results demonstrate the influence of the molecular weight of the synthetic polymer pHPMA on plasma circulation time, excretion and organ clearance. While pHPMAs are cleared from all normal tissues except the spleen quite effectively, these polymers accumulate in solid tumors in a size dependent manner, due to the well known "enhanced permeability and retention" (EPR) effect. These data are of fundamental interest for ongoing studies on the pharmacokinetics of synthetic polymers, especially when these molecules are conjugated with targeting moieties and therapeutic or diagnostic agents.


Assuntos
Adenocarcinoma/metabolismo , Metacrilatos/farmacocinética , Neoplasias Experimentais/metabolismo , Neoplasias da Próstata/metabolismo , Animais , Cromatografia Líquida de Alta Pressão , Portadores de Fármacos , Fluoresceína-5-Isotiocianato , Masculino , Taxa de Depuração Metabólica , Ratos , Distribuição Tecidual
12.
Biomed Biochim Acta ; 43(10): 1073-82, 1984.
Artigo em Inglês | MEDLINE | ID: mdl-6525185

RESUMO

The isolated purified components of the hepatic endoplasmic monooxygenatic system were incorporated into liposomes (dimyristoyl-phosphatidylcholine) by gel filtration technique. The temperature dependence of the reduction reaction in the range from 11 degrees C to 37 degrees C revealed a break in the Arrhenius-diagram at the phase transition temperature of dimyristoylphosphatidylcholine. The break point is in agreement with thermodynamic parameters derived from microcalorimetric studies of the monooxygenatic system reconstituted in the same way.


Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Dimiristoilfosfatidilcolina , Lipossomos , Animais , Cristalização , Ditionita/farmacologia , Géis , Masculino , Microssomos Hepáticos/enzimologia , NADP/farmacologia , Oxirredução , Coelhos , Temperatura
13.
Biomed Biochim Acta ; 43(3): 281-93, 1984.
Artigo em Inglês | MEDLINE | ID: mdl-6743304

RESUMO

Different techniques to incorporate the essential isolated and purified enzymes of the hepatic endoplasmic reticulum into monolamellar dimyristoylphosphatidylcholine vesicles are compared with respect to structural and functional parameters of the reconstituted system. By use of gel penetrating chromatography on Sepharose 4B, dynamic light scattering and electron microscopy the structural properties of the reconstituted system were proved comparing the reduction of P-450 LM2 via the NADPH dependent reductase and by dithionite as well with the microsomal reduction rates and by studying the binding of benzphetamine to P-450 LM2 in soluble and liposomal form.


Assuntos
Dimiristoilfosfatidilcolina/metabolismo , Lipossomos/metabolismo , Microssomos Hepáticos/metabolismo , Oxigenases de Função Mista/metabolismo , Animais , Cromatografia em Gel , Sistema Enzimático do Citocromo P-450/metabolismo , Retículo Endoplasmático/metabolismo , Técnicas In Vitro , Cinética , Masculino , Microssomos Hepáticos/enzimologia , Proteínas/metabolismo , Proteolipídeos/metabolismo , Coelhos
14.
Biochim Biophys Acta ; 692(2): 287-95, 1982 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-7171597

RESUMO

The interaction of rat liver microsomal cytochrome P-450 with phospholipids has been investigated employing differential scanning microcalorimetry. It is shown that the thermotropic behaviour of phospholipid vesicles reconstituted with cytochrome P-450 depends on liposome composition, protein concentration and the mode of reconstituted system preparation. From the delta H dependence on protein concentration in proteoliposomes it was calculated that one cytochrome P-450 molecule influence 350 +/- 50 dimyristoylphosphatidylcholine (DMPC) molecules. The electrostatic interaction of cytochrome P-450 and negatively charged phospholipid, phosphatidylinositol (PI), mixed with DMPC involves the temperature stabilization of proteoliposomes at a phase transition of phospholipid bilayers. The thermal denaturation temperature is increased due to negatively charged PI added.


Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Lipossomos , Microssomos Hepáticos/metabolismo , Fosfolipídeos/farmacologia , Animais , Varredura Diferencial de Calorimetria , Dimiristoilfosfatidilcolina , Cinética , Masculino , Fosfatidilcolinas , Fosfatidilinositóis , Proteolipídeos , Ratos , Ratos Endogâmicos , Temperatura
15.
Acta Biol Med Ger ; 38(2-3): 511-8, 1979.
Artigo em Inglês | MEDLINE | ID: mdl-517012

RESUMO

Cytochrome P-450 destruction kinetics by cumene hydroperoxide (CHP) has been studied at 25 degrees C in phosphate buffer, pH 7.25-7.50, in various systems: intact and induced rat or rabbit microsomes, highly purified LM2- and LM2- and LM4-forms of cytochrome P-450 from rabbit liver microsomes. The destruction kinetics is characterized by three phases in all systems. The CHP-influenced cytochrome P-450 destruction is a radical chain process with linear termination of the chains. The acidic phospholipids, phosphatidylserine and phosphatidylinositol and total microsomal phospholipids containing the acidic lipid components activate cytochrome P-450 in the hydroxylation of aniline and naphthalene by CHP. Phosphatidylcholine and sphingomyelin have no effect upon the cytochrome P-450 activity in the type I and II substrates oxidation by CHP. The phase transitions of the microsomal phospholipids influence the interaction of cytochrome P-450 with its reductase, altering the activation energy of type I substrates oxidation. The type II substrate oxidation is not affected by phase transitions in the full microsomal hydroxylating system.


Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Animais , Derivados de Benzeno , Cinética , Microssomos Hepáticos/efeitos dos fármacos , Microssomos Hepáticos/enzimologia , Oxirredução , Peróxidos , Fenobarbital/farmacologia , Fosfolipídeos/farmacologia , Coelhos , Ratos , Especificidade por Substrato
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