RESUMEN
Introduction: Retroperitoneal sarcoma (rps) encompasses a heterogeneous group of malignancies with a high recurrence rate after resection. Neoadjuvant radiotherapy (nrt) is often used in the hope of sterilizing margins and decreasing local recurrence after excision. We set out to compare local recurrence-free survival (lrfs) and overall survival (os) in patients treated with or without nrt before resection. Methods: Patients diagnosed with rps from February 1990 to October 2014 were identified in the Alberta Cancer Registry. Patients with complete gross resection of rps and no distant disease were included. Patient, tumour, treatment, and outcomes data were abstracted in a primary chart review. Baseline characteristics were compared using the Wilcoxon nonparametric test for continuous data and the Fisher exact test for dichotomous and categorical data. Survival was analyzed using Kaplan-Meier curves with log-rank test. Cox regression was performed to control for age, sex, tumour size, tumour grade, date of diagnosis, multivisceral resection, and intraoperative rupture. Results: Resection alone was performed in 62 patients, and resection after nrt, in 40. Use of nrt was associated with multivisceral resection and negative microscopic margins. On univariate analysis, nrt was associated with superior median lrfs (89.3 months vs. 28.4 months, p = 0.04) and os (119.4 months vs. 75.9 months, p = 0.04). On multivariate analysis, nrt, younger age, and lower tumour grade predicted improved lrfs and os; sex, tumour size, date of diagnosis, multivisceral resection, and tumour rupture did not. Conclusions: In this population-based study, nrt was associated with superior lrfs and os on both univariate and multivariate analysis. When feasible, nrt should be considered until a randomized controlled trial is completed.
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Neoplasias Retroperitoneales/radioterapia , Neoplasias Retroperitoneales/cirugía , Sarcoma/radioterapia , Sarcoma/cirugía , Femenino , Humanos , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Terapia Neoadyuvante , Clasificación del Tumor , Neoplasias Retroperitoneales/mortalidad , Neoplasias Retroperitoneales/patología , Sarcoma/mortalidad , Sarcoma/patología , Carga TumoralRESUMEN
OBJECTIVES: In the process of carcinogenesis, lipid peroxidation and increased oxidative stress lead to changes in certain antioxidants. This study was aimed to assess and co-relate serum levels of ceruloplasmin in oral premalignancies and oral cancer so as to gauge its possible association with the process of carcinogenesis and to determine its role as tumor marker. MATERIAL AND METHODS: The study population comprised of 300 participants, equally divided into six study groups, that is, oral submucous fibrosis (OSMF), oral leukoplakia (OL), nicotina stomatitis (NS), oral malignancy (OM), controls (C), and healthy controls (HC); 5 ml of blood was collected from ante cubital vein from each participant. The serum was analyzed for ceruloplasmin levels using ERBA CHEM 5 PLUS semiautomated chemistry analyzer and diagnostic kit by turbidimetric immunoassay. RESULTS: There were total 242 males and 58 females, who were between 18 and 82 years of age, with a mean of 45.31 ± 13.97 years. The serum ceruloplasmin levels were significantly increased in OM, OSMF, OL, and NS groups as compared to C and HC groups (p < .001). No statistically significant difference was found in intragroup analysis of the disease groups (p > .05). CONCLUSION: Serum ceruloplasmin can be used as diagnostic marker for oral premalignant and malignant lesions.
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Ceruloplasmina/metabolismo , Neoplasias de la Boca/sangre , Lesiones Precancerosas/sangre , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Biomarcadores de Tumor/sangre , Estudios de Casos y Controles , Estudios Transversales , Femenino , Humanos , Leucoplasia Bucal/sangre , Masculino , Persona de Mediana Edad , Fibrosis de la Submucosa Bucal/sangre , Estomatitis/sangre , Estomatitis/etiología , Fumar Tabaco/efectos adversos , Adulto JovenRESUMEN
Este estudo teve por objetivo compreender os significados atribuídos à cirurgia cardíaca par apacientes submetidos a processo cirúrgico. Participaram 1 3 pacientes submetidos a cirurgia, sendo que os instrumentos de coleta de dados utilizados foram entrevistas semi estruturadas e a autofotografia. Os dados foram analisados qualitativamente com base na análise de conteúdo das narrativas, complementada pela análise das imagens, evidenciando que os significados atribuídos à cirurgia cardíaca giraram em torno da experiência cirúrgica como geradora de sofrimento,sentimentos de despersonalização e de desamparo, medo iminente de morte e estranhamento em relação ao corpo. Destaca-se a necessidade de reconhecimento dos significados atribuídos pelos pacientes ao processo cirúrgico, por parte dos profissionais de saúde que participam da atenção à saúde desses pacientes
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Humanos , Masculino , Femenino , Adulto , Anciano , Pacientes/psicología , Cirugía TorácicaRESUMEN
Este estudo teve por objetivo compreender os significados atribuídos à cirurgia cardíaca parapacientes submetidos a processo cirúrgico. Participaram 1 3 pacientes submetidos a cirurgia, sendoque os instrumentos de coleta de dados utilizados foram entrevistas semiestruturadas e aautofotografia. Os dados foram analisados qualitativamente com base na análise de conteúdo dasnarrativas, complementada pela análise das imagens, evidenciando que os significados atribuídos àcirurgia cardíaca giraram em torno da experiência cirúrgica como geradora de sofrimento,sentimentos de despersonalização e de desamparo, medo iminente de morte e estranhamento emrelação ao corpo. Destaca-se a necessidade de reconhecimento dos significados atribuídos pelospacientes ao processo cirúrgico, por parte dos profissionais de saúde que participam da atenção àsaúde desses pacientes(AU)
Asunto(s)
Humanos , Masculino , Femenino , Adulto , Anciano , Cirugía Torácica , Pacientes/psicologíaRESUMEN
UNLABELLED: This study reports a high prevalence of hypovitaminosis D and low bone mineral density (BMD) in a healthy Hungarian male cohort over 50 years of age. Men with 25-hydroxyvitamin D levels of <75 nmol/L had a significantly higher 10-year hip and major osteoporotic fracture probability using the country-specific fracture risk assessment (FRAX) algorithm. INTRODUCTION: The aim of this study is to characterize the prevalence and seasonal variation of hypovitaminosis D and its relationship to bone metabolism in healthy Hungarian men over 50 years of age. METHODS: We determined levels of 25-hydroxyvitamin D (25-OH-D), PTH, osteocalcin (OC), C-terminal telopeptides of type-I collagen (CTX-I), procollagen type 1 amino-terminal propeptide (PINP), BMD at L1-L4 (LS) and femur neck (FN), daily dietary calcium intake, and the 10-year probability of hip fracture and a major osteoporotic fracture using the country-specific FRAX algorithm in 206 randomly selected ambulatory men. RESULTS: The mean (range) age of the volunteers was 60 (51-81) years. The prevalence of hypovitaminosis D (25-OH-D, <75 nmol/L) was 52.9%. The prevalence of low (T-score < -1.0) BMD at the FN and LS was 45% and 35.4%, respectively. The mean (range) FRAX hip fracture and FRAX major osteoporotic fracture was 0.8% (0-9.4%) and 3.8% (1.7-16%), respectively. On comparing the vitamin D sufficient to the insufficient group, there was a statistically significant difference between the FRAX hip fracture and FRAX major osteoporotic fracture indexes. There was significant seasonal variation in the vitamin D levels; the lowest levels were measured in winter and the highest in summer. CONCLUSIONS: A high prevalence of hypovitaminosis D and low BMD were observed in the studied Hungarian male population. This is the first study reporting higher 10-year hip and major osteoporotic fracture probability using the country-specific FRAX algorithm in individuals with hypovitaminosis D.
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Osteoporosis/epidemiología , Deficiencia de Vitamina D/epidemiología , Anciano , Anciano de 80 o más Años , Algoritmos , Densidad Ósea/fisiología , Estudios Transversales , Cuello Femoral/fisiopatología , Humanos , Hungría/epidemiología , Vértebras Lumbares/fisiopatología , Masculino , Persona de Mediana Edad , Osteoporosis/etiología , Osteoporosis/fisiopatología , Fracturas Osteoporóticas/epidemiología , Fracturas Osteoporóticas/etiología , Fracturas Osteoporóticas/fisiopatología , Prevalencia , Medición de Riesgo/métodos , Estaciones del Año , Vitamina D/análogos & derivados , Vitamina D/sangre , Deficiencia de Vitamina D/complicaciones , Deficiencia de Vitamina D/fisiopatologíaRESUMEN
We performed a prospective study of bone mineral density (BMD) in 38 women during their first full-term pregnancy until 12 months postpartum. BMD measurements at lumbar spine [L2-L4 (LS)] and forearm [distal 33% (RD) and ultradistal (RUD) region of the radius] were made within 3 months before conception, after delivery, and at 6 and 12 months postpartum. In mid-pregnancy the DXA examination was carried out only at the forearm. Patients were grouped according to duration of lactation as group I, II or III (0-1, 1-6, 6-12 months respectively). During pregnancy there was a significant difference between baseline and delivery (p< 0.001) in the LS, RUD and RD BMD values. In group I there was no statistically significant difference in LS BMD between visits following pregnancy. The RUD BMD loss was recovered by 6 months postpartum (PP6). Group II showed continuous bone loss from delivery until PP6 at LS and RUD. In group III the LS BMD loss continued throughout the lactation period. The RUD BMD dropped (4.9%) until PP6 then increased by 3.0% as measured at 12 months postpartum (PP12). There was no significant change in RD BMD in any of three groups during lactation. At LS bone loss between delivery and PP12 correlated well with the duration of lactation (r = -0.727; p<0.001). We suggest that calcium needed for fetal skeletal growth during pregnancy was gained from maternal trabecular and cortical sites and that calcium needed for infant growth during lactation was drawn mainly from the maternal trabecular skeleton in our patients. The effect of pregnancy and lactation on the maternal bone mass was spontaneously compensated after weaning.
Asunto(s)
Densidad Ósea/fisiología , Lactancia/fisiología , Embarazo/fisiología , Absorciometría de Fotón/métodos , Adulto , Femenino , Humanos , Estudios ProspectivosRESUMEN
We performed a prospective study in 21 patients to evaluate the cost of treatment of spasmodic torticollis (cervical dystonia) before and after botulinum toxin type A (BTA) treatment and to assess the impact of BTA treatment on quality of life. Data were recorded for the analysis over a period starting 8 months before and ending 7.2 +/- 0.2 months (mean +/- SEM) after the first injection of BTA. All patients received at least two BTA injections (2.9 +/- 0.2 injections per patient). We studied direct medical costs (drugs, outpatient and inpatient visits, diagnostic procedures, physiotherapy), clinical effects of BTA (clinical rating scale and patient's global assessment), quality of life (French version of the Nottingham Health Profile [NHP]), and adverse reactions. Costs associated with the treatment of spasmodic torticollis before the first BTA injection were 479 +/- 143 French Francs (FF)/patient/month (97 +/- 29 US $/pt/mo). During BTA treatment, costs were 1,126 +/- 147 FF/pt/mo (228 +/- 30 US $/pt/mo), including a mean cost of BTA of 771 +/- 131 FF/pt/mo (157 +/- 27 US $/pt/mo). Treatment with BTA significantly decreased clinical symptoms of spasmodic torticollis and improved the emotional, social, and pain-related domains of the quality of life assessment. Botulinum toxin type A treatment increases the cost of treating spasmodic torticollis but improves quality of life in terms of pain, social, and psychologic functioning in patients with spasmodic torticollis.
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Toxinas Botulínicas/economía , Toxinas Botulínicas/uso terapéutico , Tortícolis/tratamiento farmacológico , Tortícolis/economía , Adulto , Anciano , Toxinas Botulínicas/efectos adversos , Estudios de Cohortes , Costos y Análisis de Costo , Femenino , Humanos , Masculino , Persona de Mediana Edad , Postura , Estudios Prospectivos , Calidad de VidaRESUMEN
Numerous metal centers in proteins can be prepared in a redox state in which their ground state is paramagnetic. Complementary data provided by EPR, Mössbauer, electron nuclear double resonance, magnetic circular dichroism, and NMR spectroscopies have therefore played a major role in the elucidation of the structure and function of these centers. Among those techniques the most commonly used is certainly EPR spectroscopy. In this article various aspects of the current applications of EPR to the structural and functional study of metalloproteins are presented. They are illustrated by recent studies carried out in our laboratory in the field of metalloenzymes and electron transfer systems. The power of numerical simulation techniques is emphasized throughout this work.
Asunto(s)
Espectroscopía de Resonancia por Spin del Electrón , Metaloproteínas/química , Agaricales/enzimología , Aldehído Reductasa/química , Algoritmos , Proteínas Bacterianas/química , Simulación por Computador , Cobre/química , Cianobacterias/enzimología , Grupo Citocromo c/química , Desulfovibrio/enzimología , Espectroscopía de Resonancia por Spin del Electrón/métodos , Escherichia coli/enzimología , Hemo/química , Hierro/química , Lacasa , Modelos Químicos , Mutagénesis Sitio-Dirigida , Nitrato-Reductasa , Nitrato Reductasas/química , Oxidación-Reducción , Oxidorreductasas/química , Proteínas del Complejo del Centro de Reacción Fotosintética/química , Proteínas de Plantas/químicaRESUMEN
In vitro studies on the effect of alcoholic extracts of turmeric (TE), turmeric oil (TO) and turmeric oleoresin (TOR), on the incidence of micronuclei (Mn) in lymphocytes from normal healthy subjects showed that the test compounds did not cause any increase in the number of Mn as compared with those found in untreated controls. Further it was observed that all three compounds offered protection against benzo[a]pyrene induced increase in Mn in circulating lymphocytes. In subsequent studies, patients suffering from submucous fibrosis were given a total oral dose of TO (600 mg TO mixed with 3 g TE/day). TOR (600 mg + 3 g TE/day) and 3 g TE/day as a control for 3 months. It was observed that all three treatment modalities decreased the number of micronucleated cells both in exfoliated oral mucosal cells and in circulating lymphocytes. TOR was found to be more effective in reducing the number of Mn in oral mucosal cells (P < 0.001), but in circulating lymphocytes the decrease in Mn was comparable in all three groups.
Asunto(s)
Micronúcleos con Defecto Cromosómico/efectos de los fármacos , Neoplasias de la Boca/genética , Extractos Vegetales/farmacología , Lesiones Precancerosas/genética , Adolescente , Adulto , Curcuma , Daño del ADN , Humanos , MasculinoRESUMEN
In typical NiFe hydrogenases like that from Desulfovibrio gigas, the active state of the enzyme which is obtained by incubation under hydrogen gas gives a characteristic Ni-C electron paramagnetic resonance (EPR) signal at g = 2.19, 2.14, and 2.01. The Ni-C species is light-sensitive, being converted upon illumination at temperatures below 100 K in a mixture of different Ni-L species, the most important giving an EPR signal at g = 2.30, 2.12, and 2.05. This photoprocess is considered to correspond to the dissociation of a hydrogen species initially coordinated to the Ni ion in the Ni-C state. When the [4Fe-4S] centers of the enzyme are reduced, the proximal [4Fe-4S]1+ cluster interacts magnetically with the Ni center, which leads to complex split Ni-C or split Ni-L EPR spectra only detectable below 10 K. In order to probe the structural changes induced in the Ni center environment by the photoprocess, these spin-spin interactions were analyzed in D. gigas hydrogenase by simulating the split Ni-L spectra recorded at different microwave frequencies. We shown that, upon illumination, the relative arrangement of the Ni and [4Fe-4S] centers is not modified but that the exchange interaction between them is completely canceled. Moreover, the rotations undergone by the Ni center magnetic axes in the photoconversion were determined. Taken together, our results support a Ni-C structure in which the hydrogen species is not in the first coordination sphere of the Ni ion but is more likely bound to a sulfur atom of a terminal cysteine ligand of the Ni center.
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Desulfovibrio/enzimología , Hidrogenasas/química , Proteínas Hierro-Azufre/química , Níquel/análisis , Sitios de Unión , Espectroscopía de Resonancia por Spin del Electrón , Hidrogenasas/metabolismo , Hidrogenasas/efectos de la radiación , Proteínas Hierro-Azufre/metabolismo , Proteínas Hierro-Azufre/efectos de la radiación , Luz , Níquel/metabolismo , Conformación ProteicaRESUMEN
Total quality improvement (TQI) advocates that all staff members in an organization develop their own ideas on job improvement about their own specific jobs. This process helps to improve staff performance and to build continually on those improvements. This article will describe how the TQI process was used successfully by quality management staff members at a federal medical center to investigate a problem with linen.
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Ropa de Cama y Ropa Blanca/estadística & datos numéricos , Servicio de Lavandería en Hospital/normas , Participación en las Decisiones/organización & administración , Gestión de la Calidad Total/organización & administración , Arizona , Ropa de Cama y Ropa Blanca/economía , Comunicación , Análisis Costo-Beneficio , Hospitales con 300 a 499 Camas , Hospitales de Veteranos/economía , Hospitales de Veteranos/organización & administración , Hospitales de Veteranos/normas , Humanos , Relaciones Interprofesionales , Servicio de Lavandería en Hospital/economía , Objetivos Organizacionales , Solución de ProblemasRESUMEN
The Desulfovibrio gigas hydrogenase is a typical (NiFe) hydrogenase containing a Ni center and three FeS centers, one [3Fe-4S] and two [4Fe-4S] clusters. When the enzyme is activated under hydrogen gas, the Ni center becomes paramagnetic, giving a characteristic electron paramagnetic resonance (EPR) signal with g values at 2.19, 2.14 and 2.01, the Ni-C signal. Two redox states of the enzyme can be prepared, in which the [4Fe-4S] clusters are either diamagnetic or paramagnetic. In this latter state, the magnetic coupling between metal centers induces both the appearance at low temperature of a complex EPR spectrum, the split Ni-C signal, and a significant enhancement of the relaxation rates of the Ni center. Good simulations of the split Ni-C signal recorded at three different microwave frequencies (X-band, Q-band, and S-band) are obtained by using a model based on a point dipole approximation of the dipolar and exchange interactions between paramagnets. The spectral analysis demonstrates that only one [4Fe-4S]1+ cluster is significantly coupled to the Ni site and provides a detailed description of the relative arrangement of the two centers. In addition, the magnetic characteristics of this [4Fe-4S]1+ cluster can be deduced from the simulations. Moreover, the spin-spin and spin-lattice relaxation times of the interacting centers were measured in the two redox states of the enzyme, either by power saturation and pulsed EPR experiments at low temperature or from the broadening of the EPR lines at higher temperature. The relaxation behavior of the Ni center is well explained by using in the theoretical analysis, the set of structural and magnetic parameters deduced from the spectral simulations. Our structural conclusions on the active D. gigas hydrogenase are compared to the preliminary data of a low-resolution crystal structure of the oxidized enzyme [Volbeda, A., Piras, C., Charon, M. H., Hatchikian, E. C., Frey, M., & Fontecilla-Camps, J. C. (1993) News Lett. Protein Crystallogr. 28, 30-33].
Asunto(s)
Desulfovibrio/enzimología , Hidrogenasas/química , Proteínas Hierro-Azufre/química , Níquel/química , Espectroscopía de Resonancia por Spin del Electrón , Activación Enzimática , Hidrogenasas/metabolismo , Magnetismo , Conformación Proteica , TemperaturaRESUMEN
The elucidation of the role of the four hemes in cytochromes c3 requires several complementary approaches. The measurements and the assignment of the redox potentials resort to magnetic spectroscopies, EPR and NMR, which are able to discriminate the hemes. The origin of the differences between the redox properties of the hemes can be studied by comparing their thermodynamic parameters delta S and delta H, as measured by the temperature dependence of their individual potentials. Lastly, the available data concerning the electron exchange between cytochromes c3 and their redox partners can be analysed through a detailed kinetic model which provides important information on the role of the different hemes.
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Grupo Citocromo c/química , Hemo/química , Desulfovibrio vulgaris/enzimología , Espectroscopía de Resonancia por Spin del Electrón , Cinética , Espectroscopía de Resonancia Magnética , Oxidación-Reducción , TemperaturaRESUMEN
The beta-subunit of the nitrate reductase of Escherichia coli contains four groups of Cys residues (I-IV) which are thought to bind the single [3Fe-4S] center and the three [4Fe-4S] centers. The first or second Cys residue of group I was substituted by site-directed mutagenesis with Ala or Ser. Physiological, biochemical, and EPR studies were performed on the mutated enzymes. With small variations, the properties of these mutant enzymes do not differ from one another. They were found to be as abundant and as stably bound to the membrane as the native enzyme, provided the gamma-subunit was present. Although physiological activity was reduced, it was sufficient to allow growth on nitrate. The study of variations in EPR intensity as a function of the redox potential indicated that these enzymes only contained three iron-sulfur centers instead of the usual four in the native enzyme. Spectral EPR analysis showed that the [4Fe-4S] center of high redox potential (center 1, +80 mV) was missing. The loss of this center did not affect the stable integration of the other three centers. The data presented here are in total contrast to those we have reported for each of the other three centers (centers 2-4), the loss of which was detrimental to the integration of all centers and to the integration of the molybdenum cofactor (Augier et al., in press). Taken together, our results demonstrated that the first and second Cys residues of group I are the ligands of the [4Fe-4S] center (center 1, +80 mV) and that this center participates in electron transfer, but is dispensable. On the basis of these results, it is proposed that the [3Fe-4S] center (center 2, +60 mV) also plays a biological role and that in the native enzyme both high-potential centers, centers 1 and 2, contribute independently and in parallel to the electron transfer to the molybdenum cofactor.
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Escherichia coli/enzimología , Proteínas Hierro-Azufre/química , Mutagénesis Sitio-Dirigida , Nitrito Reductasas/química , Membrana Celular/enzimología , Cisteína/química , Cisteína/metabolismo , Espectroscopía de Resonancia por Spin del Electrón , Transporte de Electrón , Técnicas de Inmunoadsorción , Nitrito Reductasas/genética , Nitrito Reductasas/metabolismo , Oxidación-Reducción , Plásmidos , Relación Estructura-ActividadRESUMEN
The structural properties of the iron-sulfur centers of photosystem I (PSI) from the cyanobacterium Synechocystis 6803 have been investigated by EPR spectrometry. The stoichiometry of centers A, B, and X, determined by EPR intensity measurements, gives direct evidence for center X being a [4Fe-4S] center in the native system and for the core reaction center protein being a dimer. The directions of the magnetic axes of centers A, B, and X were accurately determined by EPR experiments carried out on membrane fragments oriented on thin Mylar films. These directions are very similar to those previously reported for plants and algae. To get a detailed description of the relative arrangement of A and B, the magnetic interactions between these centers have been analyzed through numerical simulations of X-band and Q-band EPR spectra. The relative orientation of the magnetic axes deduced from these simulations is fully consistent with that given by oriented multilayer experiments. Numerical simulations of X-band and Q-band EPR spectra given by spinach PSI lead to a very similar set of structural parameters, which demonstrates that the functional unit of PSI is highly conserved in all photosynthetic organisms. Moreover, the results of these studies indicate that the A-B direction is close to the membrane normal, which supports a sequential electron transfer mechanism between the iron-sulfur centers in PSI.
Asunto(s)
Cianobacterias/metabolismo , Proteínas Hierro-Azufre/química , Proteínas del Complejo del Centro de Reacción Fotosintética/química , Espectroscopía de Resonancia por Spin del Electrón , Membranas Intracelulares/química , Membranas Intracelulares/metabolismo , Proteínas Hierro-Azufre/metabolismo , Cinética , Proteínas del Complejo del Centro de Reacción Fotosintética/metabolismo , Complejo de Proteína del Fotosistema I , Conformación ProteicaRESUMEN
The redox properties of the iron-sulfur centers of the two nitrate reductases from Escherichia coli have been investigated by EPR spectroscopy. A detailed study of nitrate reductase A performed in the range +200 mV to -500 mV shows that the four iron-sulfur centers of the enzyme belong to two classes with markedly different redox potentials. The high-potential group comprises a [3Fe-4S] and a [4Fe-4S] cluster whose midpoint potentials are +60 mV and +80 mV, respectively. Although these centers are magnetically isolated, they are coupled by a significant anticooperative redox interaction of about 50 mV. The [4Fe-4S]1+ center occurs in two different conformations as shown by its composite EPR spectrum. The low-potential group contains two [4Fe-4S] clusters with more typical redox potentials (-200 mV and -400 mV). In the fully reduced state, the three [4Fe-4S]1+ centers are magnetically coupled, leading to a broad featureless spectrum. The redox behaviour of the high-pH EPR signal given by the molybdenum cofactor was also studied. The iron-sulfur centers of the second nitrate reductase of E. coli, nitrate reductase Z, exhibit essentially the same characteristics than those of nitrate reductase A, except that the midpoint potentials of the high-potential centers appear negatively shifted by about 100 mV. From the comparison between the redox centers of nitrate reductase and of dimethylsulfoxide reductase, a correspondence between the high-potential iron-sulfur clusters of the two enzymes can be proposed.
Asunto(s)
Escherichia coli/enzimología , Proteínas Hierro-Azufre/química , Isoenzimas/química , Nitrato Reductasas/química , Membrana Celular/enzimología , Espectroscopía de Resonancia por Spin del Electrón , Transporte de Electrón , Proteínas Hierro-Azufre/genética , Proteínas Hierro-Azufre/metabolismo , Isoenzimas/genética , Isoenzimas/metabolismo , Modelos Teóricos , Nitrato Reductasas/genética , Nitrato Reductasas/metabolismo , Oxidación-Reducción , Oxidorreductasas/metabolismo , PlásmidosRESUMEN
The gene of high molecular weight, multiheme cytochrome c (Hmc) from the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough has been overexpressed in Desulfovibrio desulfuricans G200. The recombinant protein has been purified. Its molecular weight (65,600), amino acid composition, and NH2-terminal sequence were found to be identical to those of the wild-type protein. The recombinant protein has been spectroscopically characterized (optical spectrum, EPR, circular dichroism) and compared to the wild-type protein. We have found 16 hemes per molecule by iron analysis and the pyridine hemochrome test. Both high- and low-spin features were observed in the EPR spectrum. A detailed spin quantitation analysis indicates 1 or 2 high-spin hemes and 14 or 15 low-spin hemes per molecule. The redox potentials of the hemes determined by voltammetric techniques gave an average of three different values, 0, -100, and -250 mV (versus NHE), for the wild-type and the recombinant cytochrome. The low potential values are similar to the values observed for the bis(histidinyl) coordinated hemes of cytochrome c3. A comparison of the arrangement of heme binding sites and coordinated histidines in the amino acid sequences of cytochrome c3 and Hmc has shown that the latter contains four domains, three of which are complete c3-like domains, while the fourth represents an incomplete c3-like domain which may contain His-Met coordinated hemes. These data are in agreement with the detailed study of the number and types of hemes reported in this paper.
Asunto(s)
Grupo Citocromo c/genética , Desulfovibrio vulgaris/genética , Vectores Genéticos , Secuencia de Aminoácidos , Aminoácidos/análisis , Fenómenos Químicos , Química Física , Dicroismo Circular , Grupo Citocromo c/biosíntesis , Grupo Citocromo c/química , Desulfovibrio vulgaris/enzimología , Electroquímica , Espectroscopía de Resonancia por Spin del Electrón , Genes Bacterianos , Hemo/análisis , Hierro/análisis , Datos de Secuencia Molecular , Peso Molecular , Proteínas Recombinantes/química , Proteínas Recombinantes/aislamiento & purificaciónRESUMEN
A single crystal of cytochrome c3 from Desulfovibrio desulfuricans Norway is studied by electron paramagnetic resonance at low temperature. The orientation of the principal axis corresponding to the largest g value is determined for the 12 heme groups in the crystal unit cell. The comparison of these directions to the normals to the heme planes, determined from the crystallographic data at 2.5 A resolution, gives strong evidence for the following assignment of the midpoint redox potentials to the heme groups H1 to H4, defined in the three-dimensional structure: -150 mV is assigned to H3, -300 mV to H4, -330 mV to H1 and -355 mV to H2. This assignment is in agreement with a partial correspondence previously established from an independent study performed on cytochrome c3 in solution.
Asunto(s)
Grupo Citocromo c/metabolismo , Desulfovibrio/metabolismo , Grupo Citocromo c/aislamiento & purificación , Espectroscopía de Resonancia por Spin del Electrón/métodos , Hemo/metabolismo , Oxidación-Reducción , Conformación ProteicaRESUMEN
The validity of self-reports of 48 adults with mental retardation of daily living competency using the recently revised Vineland Adaptive Behavior Scales (Sparrow, Balla, & Cicchetti, 1984) was investigated. Self-report was compared to standard Vineland interviews of subjects' program counselors and to demonstrated competency in a real-life setting. On domains measuring adaptive skills, the subject and counselor interviews yielded highly consistent results. On the optional Maladaptive Behavior domain, however, the subjects with mental retardation underreported problematic behavior. Response validity and implications for use of self-report for program planning and placement decisions were discussed.