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1.
J Clin Oncol ; 41(24): 3965-3972, 2023 Aug 20.
Artículo en Inglés | MEDLINE | ID: mdl-37586209

RESUMEN

PURPOSE: The Southwest Oncology Group (SWOG) coordinated an Intergroup study with the participation of Radiation Therapy Oncology Group (RTOG), and Eastern Cooperative Oncology Group (ECOG). This randomized phase III trial compared chemoradiotherapy versus radiotherapy alone in patients with nasopharyngeal cancers. MATERIALS AND METHODS: Radiotherapy was administered in both arms: 1.8- to 2.0-Gy/d fractions Monday to Friday for 35 to 39 fractions for a total dose of 70 Gy. The investigational arm received chemotherapy with cisplatin 100 mg/m2 on days 1, 22, and 43 during radiotherapy; postradiotherapy, chemotherapy with cisplatin 80 mg/m2 on day 1 and fluorouracil 1,000 mg/m2/d on days 1 to 4 was administered every 4 weeks for three courses. Patients were stratified by tumor stage, nodal stage, performance status, and histology. RESULTS: Of 193 patients registered, 147 (69 radiotherapy and 78 chemoradiotherapy) were eligible for primary analysis for survival and toxicity. The median progression-free survival (PFS) time was 15 months for eligible patients on the radiotherapy arm and was not reached for the chemo-radiotherapy group. The 3-year PFS rate was 24% versus 69%, respectively (P < .001). The median survival time was 34 months for the radiotherapy group and not reached for the chemo-radiotherapy group, and the 3-year survival rate was 47% versus 78%, respectively (P = .005). One hundred eighty-five patients were included in a secondary analysis for survival. The 3-year survival rate for patients randomized to radiotherapy was 46%, and for the chemoradiotherapy group was 76% (P < .001). CONCLUSION: We conclude that chemoradiotherapy is superior to radiotherapy alone for patients with advanced nasopharyngeal cancers with respect to PFS and overall survival.

2.
Phys Rev Lett ; 126(2): 023201, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33512178

RESUMEN

Chirality causes symmetry breaks in a large variety of natural phenomena ranging from particle physics to biochemistry. We investigate one of the simplest conceivable chiral systems, a laser-excited, oriented, effective one-electron Li target. Prepared in a polarized p state with |m|=1 in an optical trap, the atoms are exposed to co- and counterrotating circularly polarized femtosecond laser pulses. For a field frequency near the excitation energy of the oriented initial state, a strong circular dichroism is observed and the photoelectron energies are significantly affected by the helicity-dependent Autler-Townes splitting. Besides its fundamental relevance, this system is suited to create spin-polarized electron pulses with a reversible switch on a femtosecond timescale at an energy resolution of a few meV.

3.
J Laryngol Otol ; 127(7): 676-80, 2013 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-23790108

RESUMEN

BACKGROUND: Although positron emission tomography computed tomography has proven diagnostic and staging value in head and neck carcinoma, it does not have optimal sensitivity or specificity. The positron emission tomography computed tomography fluorodeoxyglucose standardised uptake value has been shown to be associated with carcinoma stage. This study evaluated the impact of major clinicopathological factors on the standardised uptake value at the primary site and at neck lymph node metastases. SUBJECTS AND METHODS: Two hundred and forty-three oral cavity and laryngopharyngeal carcinoma patients who underwent positron emission tomography computed tomography were included. Correlation between the positron emission tomography computed tomography standardised uptake value and various clinicopathological factors was analysed. RESULTS: A positive correlation was found between the standardised uptake value and the size and depth of tumour infiltration, and lymph node positivity. Higher standardised uptake values were seen for more advanced tumour stages. The presence of perineural invasion, lymphatic invasion and extracapsular spread were all associated with increased standardised uptake values. CONCLUSION: Most of the clinicopathological features of head and neck carcinoma which are well known to be poor prognostic factors have a significant impact on positron emission tomography computed tomography fluorodeoxyglucose standardised uptake value.


Asunto(s)
Carcinoma de Células Escamosas/diagnóstico por imagen , Fluorodesoxiglucosa F18 , Neoplasias de Cabeza y Cuello/diagnóstico por imagen , Tomografía de Emisión de Positrones/métodos , Carcinoma de Células Escamosas/patología , Fluorodesoxiglucosa F18/metabolismo , Neoplasias de Cabeza y Cuello/patología , Humanos , Metástasis Linfática/diagnóstico por imagen , Metástasis Linfática/patología , Radiofármacos , Sensibilidad y Especificidad , Carcinoma de Células Escamosas de Cabeza y Cuello
4.
J Microbiol Methods ; 93(3): 206-8, 2013 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-23545448

RESUMEN

We herein present a high-throughput and cheap method for yeast DNA isolation in a 96 well microplate. About 1500 yeast isolates can be processed within one working day and final DNA concentrations are suitable for direct application in PCR-based molecular typing methods.


Asunto(s)
ADN de Hongos/aislamiento & purificación , Técnicas Microbiológicas/métodos , Biología Molecular/métodos , Manejo de Especímenes/métodos , Levaduras/genética , Técnicas Microbiológicas/economía , Biología Molecular/economía , Tipificación Molecular/métodos , Técnicas de Tipificación Micológica/métodos , Manejo de Especímenes/economía , Factores de Tiempo
5.
Appl Microbiol Biotechnol ; 97(11): 4991-5000, 2013 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-23361840

RESUMEN

Excessive volatile acidity in wines is a major problem and is still prevalent because available solutions are nevertheless unsatisfactory, namely, blending the filter-sterilized acidic wine with other wines of lower volatile acidity or using reverse osmosis. We have previously explored the use of an empirical biological deacidification procedure to lower the acetic acid content of wines. This winemaker's enological practice, which consists in refermentation associated with acetic acid consumption by yeasts, is performed by mixing the acidic wine with freshly crushed grapes, musts, or marc from a finished wine fermentation. We have shown that the commercial strain Saccharomyces cerevisiae S26 is able to decrease the volatile acidity of acidic wines with a volatile acidity higher than 1.44 g L(-1) acetic acid, with no detrimental impact on wine aroma. In this study, we aimed to optimize the immobilization of S26 cells in alginate beads for the bioreduction of volatile acidity of acidic wines. We found that S26 cells immobilized in double-layer alginate-chitosan beads could reduce the volatile acidity of an acidic wine (1.1 g L(-1) acetic acid, 12.5 % (v/v) ethanol, pH 3.12) by 28 and 62 % within 72 and 168 h, respectively, associated with a slight decrease in ethanol concentration (0.7 %). Similar volatile acidity removal efficiencies were obtained in medium with high glucose concentration (20 % w/v), indicating that this process may also be useful in the deacidification of grape musts. We, therefore, show that immobilized S. cerevisiae S26 cells in double-layer beads are an efficient alternative to improve the quality of wines with excessive volatile acidity.


Asunto(s)
Ácidos Carboxílicos/metabolismo , Saccharomyces cerevisiae/metabolismo , Compuestos Orgánicos Volátiles/metabolismo , Vino/análisis , Vino/microbiología , Alginatos , Biotecnología/métodos , Células Inmovilizadas/metabolismo , Microbiología de Alimentos/métodos , Ácido Glucurónico , Ácidos Hexurónicos , Microesferas
6.
Int J Food Microbiol ; 141(3): 165-72, 2010 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-20626097

RESUMEN

Herein, we evaluate the applicability of previously characterized commercial and indigenous Saccharomyces cerevisiae strains and non-S. cerevisiae species for the deacidification of white and red wines at a pilot scale. The effect of the refermentation process (mixture of acidic wine with musts from freshly crushed grapes or with residual marc) as well as micro-oxygenation (MO) on acetic acid removal efficiency and wine aromatic composition was also assessed in a red wine. The commercial strains S26 and S29 efficiently reduced both acetic acid (43 and 47%, respectively) and sugar (100%) after 264 h of refermentation of an acidic white wine that was supplemented with grape must. Similar results (60-66% of acetic acid removal) were observed for red wine deacidification using grape must, independently of MO. When residual marc was used for deacidification, strain S26 removed 40% of acetic acid, whereas strain S29 did not initiate refermentation with or without MO. Wines obtained by refermentation with the must had significantly lower acetic acid and a higher total SO(2) concentration in comparison to the wines deacidified by the grape marcs. The volatile aroma compound's composition of deacidified red wines was dependent on the refermentation process used, rather than on MO. Themarc-deacidified wine obtained by the use of strain S26 and without MO achieved the best sensory classification.When data from all analytical and sensory evaluation were combined, Principal Component Analysis (PCA) separated the wines into three distinct groups according to the strain and the refermentation process independently of MO. We successfully established an efficient and cheap enological solution for the rectification of volatile acidity of wines.


Asunto(s)
Ácido Acético/metabolismo , Fermentación , Oxígeno/metabolismo , Saccharomyces cerevisiae/metabolismo , Compuestos Orgánicos Volátiles/metabolismo , Vino/microbiología , Ácido Acético/análisis , Humanos , Saccharomyces cerevisiae/química , Gusto , Compuestos Orgánicos Volátiles/análisis , Vino/análisis
7.
Yeast ; 26(12): 675-92, 2009 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19894212

RESUMEN

Within this study, we have used a set of computational techniques to relate the genotypes and phenotypes of natural populations of Saccharomyces cerevisiae, using allelic information from 11 microsatellite loci and results from 24 phenotypic tests. A group of 103 strains was obtained from a larger S. cerevisiae winemaking strain collection by clustering with self-organizing maps. These strains were further characterized regarding their allelic combinations for 11 microsatellites and analysed in phenotypic screens that included taxonomic criteria (carbon and nitrogen assimilation tests, growth at different temperatures) and tests with biotechnological relevance (ethanol resistance, H(2)S or aromatic precursors formation). Phenotypic variability was rather high and each strain showed a unique phenotypic profile. The results, expressed as optical density (A(640)) after 22 h of growth, were in agreement with taxonomic data, although with some exceptions, since few strains were capable of consuming arabinose and ribose to a small extent. Based on microsatellite allelic information, naïve Bayesian classifier correctly assigned (AUC = 0.81, p < 10(-8)) most of the strains to the vineyard from where they were isolated, despite their close location (50-100 km). We also identified subgroups of strains with similar values of a phenotypic feature and microsatellite allelic pattern (AUC > 0.75). Subgroups were found for strains with low ethanol resistance, growth at 30 degrees C and growth in media containing galactose, raffinose or urea. The results demonstrate that computational approaches can be used to establish genotype-phenotype relations and to make predictions about a strain's biotechnological potential.


Asunto(s)
Saccharomyces cerevisiae/genética , Vino/microbiología , Alelos , Secuencia de Bases , Teorema de Bayes , Biología Computacional , Cartilla de ADN/genética , ADN de Hongos/genética , Estudios de Asociación Genética , Variación Genética , Genotipo , Repeticiones de Microsatélite , Modelos Genéticos , Fenotipo , Saccharomyces cerevisiae/clasificación , Saccharomyces cerevisiae/aislamiento & purificación , Saccharomyces cerevisiae/metabolismo , Vitis/crecimiento & desarrollo
8.
Appl Microbiol Biotechnol ; 80(5): 881-90, 2008 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-18677471

RESUMEN

Herein, we isolate and characterize wine yeasts with the ability to reduce volatile acidity of wines using a refermentation process, which consists in mixing the acidic wine with freshly crushed grapes or musts or, alternatively, in the incubation with the residual marc. From a set of 135 yeast isolates, four strains revealed the ability to use glucose and acetic acid simultaneously. Three of them were identified as Saccharomyces cerevisiae and one as Lachancea thermotolerans. Among nine commercial S. cerevisiae strains, strains S26, S29, and S30 display similar glucose and acetic acid initial simultaneous consumption pattern and were assessed in refermentation assays. In a medium containing an acidic wine with high glucose-low ethanol concentrations, under low oxygen availability, strain S29 is the most efficient one, whereas L. thermotolerans 44C is able to decrease significantly acetic acid similar to the control strain Zygosaccharomyces bailii ISA 1307 but only under aerobic conditions. Conversely, for low glucose-high ethanol concentrations, under aerobic conditions, S26 is the most efficient acid-degrading strain, while under limited-aerobic conditions, all the S. cerevisiae strains studied display acetic acid degradation efficiencies identical to Z. bailii. Moreover, S26 strain also reveals capacity to decrease volatile acidity of wines. Together, the S. cerevisiae strains characterized herein appear promising for the oenological removal of volatile acidity of acidic wines.


Asunto(s)
Ácido Acético/metabolismo , Microbiología de Alimentos , Microbiología Industrial , Vino/microbiología , Levaduras/metabolismo , Etanol/metabolismo , Fermentación , Glucosa/metabolismo , Saccharomyces cerevisiae , Vitis/metabolismo , Volatilización , Vino/análisis , Levaduras/genética , Levaduras/aislamiento & purificación
9.
Oncogene ; 25(9): 1424-33, 2006 Mar 02.
Artículo en Inglés | MEDLINE | ID: mdl-16247453

RESUMEN

Gene amplification, a common mechanism for oncogene activation in cancer, has been used as a tag for the identification of novel oncogenes. DNA amplification is frequently observed in head and neck squamous cell carcinoma (HNSCC) and potential oncogenes have already been reported. We applied restriction landmark genome scanning (RLGS) to study gene amplifications and low-level copy number changes in HNSCC in order to locate previously uncharacterized regions with copy number gains in primary tumor samples. A total of 63 enhanced RLGS fragments, indicative of DNA copy number changes, including gains of single alleles, were scored. Enhanced sequences were identified from 33 different chromosomal regions including those previously reported (e.g. 3q26.3 and 11q13.3) as well as novel regions (e.g. 3q29, 8q13.1, 8q22.3, 9q32, 10q24.32, 14q32.32, 17q25.1 and 20q13.33). Furthermore, our data suggest that amplicons 11q13.3 and 3q26.3-q29 may be divided into possibly two and three independent amplicons, respectively, an observation supported by published microarray expression data.


Asunto(s)
Carcinoma de Células Escamosas/genética , Amplificación de Genes , Dosificación de Gen , Neoplasias de Cabeza y Cuello/genética , Cromosomas Humanos Par 11 , Cromosomas Humanos Par 3 , Humanos , Mapeo Restrictivo
10.
Acta Crystallogr D Biol Crystallogr ; 59(Pt 7): 1262-4, 2003 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-12832779

RESUMEN

Mouse and Heligmosomoides polygyrus constitute a readily manipulated small-animal laboratory model for investigating host-nematode interactions. Two major forms of glutathione transferase (GST) are expressed in H. polygyrus adult worms following primary infection. One of these forms belongs to a new class of GST which has only been found in the nematode phylum and therefore presents a possible target for nematode control. In this study, crystals were obtained of a recombinant representative of this new GST class from H. polygyrus. These crystals belong to the triclinic space group P1, with unit-cell parameters a = 72.7, b = 74.0, c = 88.6 A, alpha = 79.1, beta = 80.1, gamma = 81.5 degrees, and are likely to contain four homodimers in the asymmetric unit. X-ray diffraction data were collected to 1.8 A resolution on station A1 at the Cornell High-Energy Synchrotron Source (CHESS).


Asunto(s)
Glutatión Transferasa/química , Proteínas del Helminto/química , Nematodos/enzimología , Animales , Cristalización , Cristalografía por Rayos X/métodos , Nematospiroides dubius/enzimología , Proteínas Recombinantes
11.
J Med Genet ; 40(1): 25-33, 2003 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-12525538

RESUMEN

Head and neck squamous cell carcinomas (HNSCC) often metastasise to the cervical lymph nodes. It is known for HNSCC as well as other cancers that progression from normal tissue to primary tumour and finally to metastatic tumour is characterised by an accumulation of genetic mutations. DNA methylation, an epigenetic modification, can result in loss of gene function in cancer, similar to genetic mutations such as deletions and point mutations. We have investigated the DNA methylation phenotypes of both primary HNSCC and metastatic tumours from 13 patients using restriction landmark genomic scanning (RLGS). With this technique, we were able to assess the methylation status of an average of nearly 1300 CpG islands for each tumour. We observed that the number of CpG islands hypermethylated in metastatic tumours is significantly greater than what is found in the primary tumours overall, but not in every patient. Interestingly, the data also clearly show that many loci methylated in a patient's primary tumour are no longer methylated in the metastatic tumour of the same patient. Thus, even though metastatic HNSCC methylate a greater proportion of CpG islands than do the primary tumours, they do so at different subsets of loci. These data show an unanticipated variability in the methylation state of loci in primary and metastatic HNSCCs within the same patient. We discuss two possible explanations for how different epigenetic events might arise between the primary tumour and the metastatic tumour of a person.


Asunto(s)
Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/secundario , Islas de CpG/genética , Metilación de ADN , Neoplasias de Cabeza y Cuello/genética , Neoplasias de Cabeza y Cuello/patología , Adulto , Anciano , Clonación Molecular , Dermatoglifia del ADN , Femenino , Marcadores Genéticos/genética , Humanos , Neoplasias Laríngeas/genética , Neoplasias Laríngeas/patología , Metástasis Linfática/genética , Masculino , Persona de Mediana Edad , Neoplasias de la Boca/genética , Neoplasias de la Boca/patología , Neoplasias Faríngeas/genética , Neoplasias Faríngeas/patología , Fenotipo , Mapeo Restrictivo , Análisis de Secuencia de ADN , Sulfitos/metabolismo
12.
FEBS Lett ; 532(3): 324-32, 2002 Dec 18.
Artículo en Inglés | MEDLINE | ID: mdl-12482587

RESUMEN

The PKC1 gene in the yeast Saccharomyces cerevisiae encodes for protein kinase C which is known to control a MAP kinase cascade consisting of different kinases: Bck1, Mkk1 and Mkk2, and Mpk1. This cascade affects the cell wall integrity but the phenotype of pkc1Delta mutants suggests additional targets that have not yet been identified [Heinisch et al., Mol. Microbiol. 32 (1999) 671-680]. The pkc1Delta mutant, as opposed to other mutants in the MAP kinase cascade, displays defects in the control of carbon metabolism. One of them occurs in the derepression of SUC2 gene after exhaustion of glucose from the medium, suggesting an involvement of Pkc1p in the derepression process that is not shared by the downstream MAP kinase cascade. In this work, we demonstrate that Pkc1p is required for the increase of the activity of enzymatic systems during the derepression process. We observed that Pkc1p is involved in the derepression of invertase and alcohol dehydrogenase activities. On the other hand, it seems not to be necessary for the derepression of the enzymes of the GAL system. Our results suggest that Pkc1p is acting through the main glucose repression pathway, since introduction of an additional mutation in the PKC1 gene in yeast strains already presenting mutations in the HXKII or MIG1 genes does not interfere with the typical derepressed phenotype observed in these single mutants. Moreover, our data indicate that Pkc1p participates in this process through the control of the cellular localization of the Mig1 transcriptional factor.


Asunto(s)
Proteína Quinasa C/metabolismo , Saccharomyces cerevisiae/enzimología , Agar/farmacología , Alcohol Deshidrogenasa/metabolismo , Northern Blotting , Western Blotting , División Celular , Proteínas de Unión al ADN/metabolismo , Relación Dosis-Respuesta a Droga , Epítopos , Glucosa/metabolismo , Glicósido Hidrolasas/metabolismo , Proteínas Fluorescentes Verdes , Proteínas Luminiscentes/metabolismo , Mutación , Fenotipo , Unión Proteica , Proteína Quinasa C/genética , ARN/metabolismo , Proteínas Represoras/metabolismo , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae , Factores de Tiempo , Transcripción Genética , beta-Fructofuranosidasa
13.
Int J Oncol ; 21(2): 401-8, 2002 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-12118338

RESUMEN

Inactivation of the p16 tumor suppressor gene is a common phenomenon in squamous cell carcinoma of the head and neck (SCCHN). Less commonly described is the observation of p16 overexpression in SCCHN. Since overexpression of p16 is a potent predictor of outcome in other cancers, we were interested in determining the level of expression of p16 in our SCCHN specimens as a prerequisite to later prognostic studies. We were also interested in determining the mutational status of p16 in these tumors, in order to determine whether the combination of overexpression and gene alteration may predict a different clinical outcome from overexpression alone. A total of 84 specimens of SCCHN were selected for study. These specimens were obtained from all major sites within the oral cavity, oropharynx, pharynx and larynx. The level of expression of p16 in SCCHN specimens was measured by semi-quantitative RT-PCR. In 35 cases, RNA was also isolated from matched normal tissue obtained from a negative tumor margin. In the other 49 cases, the expression level was compared with the level of expression measured in pooled normal RNA obtained from 10 specimens of normal epithelial tissue. Overexpression of p16 was documented when the level of expression in the tumor specimen was 2-fold or greater above the level of expression found in normal tissue. A total of 46 specimens demonstrated overexpression of p16 (55%). All specimens demonstrating overexpression were then subject to sequence analysis. Thirty specimens (65%) showed p16-specific gene alterations, ranging from intragenic deletions to single point mutations, and 15 of these cases concomitantly affect p14ARF. A single specimen demonstrated a silent point mutation within the p16 reading frame. This mutation produces a stop codon at residue 85 in the context of the p14ARF reading frame, predicting premature termination of p14ARF within a previously determined nucleolar localization signal. This observation suggests that in some cases at least, p14ARF may be a selective target for alteration, independently of p16. Analysis of a normal tissue specimen obtained from a negative tumor margin, and a blood sample obtained approximately five years after surgery indicate that this p14ARF-specific alteration may represent a germline mutation.


Asunto(s)
Carcinoma de Células Escamosas/genética , Inhibidor p16 de la Quinasa Dependiente de Ciclina/genética , Mutación de Línea Germinal , Neoplasias de Cabeza y Cuello/genética , Proteína p14ARF Supresora de Tumor/genética , Inhibidor p16 de la Quinasa Dependiente de Ciclina/metabolismo , Cartilla de ADN/química , Eliminación de Gen , Humanos , ARN Mensajero/metabolismo , ARN Neoplásico/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Proteína p14ARF Supresora de Tumor/metabolismo , Regulación hacia Arriba
14.
Biochemistry ; 40(45): 13483-90, 2001 Nov 13.
Artículo en Inglés | MEDLINE | ID: mdl-11695895

RESUMEN

The crystal structure of the fully oxidized di-heme peroxidase from Nitrosomonas europaea has been solved to a resolution of 1.80 A and compared to the closely related enzyme from Pseudomonas aeruginosa. Both enzymes catalyze the peroxide-dependent oxidation of a protein electron donor such as cytochrome c. Electrons enter the enzyme through the high-potential heme followed by electron transfer to the low-potential heme, the site of peroxide activation. Both enzymes form homodimers, each of which folds into two distinct heme domains. Each heme is held in place by thioether bonds between the heme vinyl groups and Cys residues. The high-potential heme in both enzymes has Met and His as axial heme ligands. In the Pseudomonas enzyme, the low-potential heme has two His residues as axial heme ligands [Fulop et al. (1995) Structure 3, 1225-1233]. Since the site of reaction with peroxide is the low-potential heme, then one His ligand must first dissociate. In sharp contrast, the low-potential heme in the Nitrosomonas enzyme already is in the "activated" state with only one His ligand and an open distal axial ligation position available for reaction with peroxide. A comparison between the two enzymes illustrates the range of conformational changes required to activate the Pseudomonas enzyme. This change involves a large motion of a loop containing the dissociable His ligand from the heme pocket to the molecular surface where it forms part of the dimer interface. Since the Nitrosomonas enzyme is in the active state, the structure provides some insights on residues involved in peroxide activation. Most importantly, a Glu residue situated near the peroxide binding site could possibly serve as an acid-base catalytic group required for cleavage of the peroxide O--O bond.


Asunto(s)
Citocromo-c Peroxidasa/química , Nitrosomonas/enzimología , Secuencia de Aminoácidos , Cristalización , Dimerización , Hemo/química , Ligandos , Modelos Moleculares , Datos de Secuencia Molecular , Peroxidasas/química , Conformación Proteica , Estructura Terciaria de Proteína , Homología de Secuencia de Aminoácido
15.
Biochemistry ; 40(38): 11552-8, 2001 Sep 25.
Artículo en Inglés | MEDLINE | ID: mdl-11560504

RESUMEN

We report the crystal structure of heme oxygenase from the pathogenic bacterium Neisseria meningitidis at 1.5 A and compare and contrast it with known structures of heme oxygenase-1 from mammalian sources. Both the bacterial and mammalian enzymes share the same overall fold, with a histidine contributing a ligand to the proximal side of the heme iron and a kinked alpha-helix defining the distal pocket. The distal helix differs noticeably in both sequence and conformation, and the distal pocket of the Neisseria enzyme is substantially smaller than in the mammalian enzyme. Key glycine residues provide the flexibility for the helical kink, allow close contact of the helix backbone with the heme, and may interact directly with heme ligands.


Asunto(s)
Hemo Oxigenasa (Desciclizante)/química , Neisseria meningitidis/enzimología , Animales , Catálisis , Cristalografía por Rayos X/métodos , Glicina , Hemo Oxigenasa (Desciclizante)/metabolismo , Hemo-Oxigenasa 1 , Humanos , Mamíferos , Proteínas de la Membrana , Modelos Moleculares , Conformación Proteica , Estructura Secundaria de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo
16.
Invest New Drugs ; 19(4): 311-5, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-11561690

RESUMEN

A phase II trial of gemcitabine (Gemzar), a nucleoside analogue with broad activity in solid tumors, was performed in patients with recurrent or metastatic squamous cell carcinoma of the head and neck. A total of 26 eligible patients were registered to receive a dose of 1250 mg/m2 weekly for 3 weeks, followed by a 1 week rest. Toxicity was evaluable in 26 patients. Nausea and vomiting occured in 11 and 6 patients, repectively. Grade 3 or 4 hematologic toxicities were infrequent. Two patients developed neutropenic infections. One patient developed fatal liver failure which was thought due to progressive liver metastases or infection 14 days after a single dose of gemcitabine. There were no objective treatment responses (95% CI 0-13%), with a median survival of 6 months in this highly resistant disease population. Gemcitabine is not considered active enough as monotherapy for further evaluation in this disease population.


Asunto(s)
Antimetabolitos Antineoplásicos/uso terapéutico , Carcinoma de Células Escamosas/tratamiento farmacológico , Desoxicitidina/análogos & derivados , Desoxicitidina/uso terapéutico , Neoplasias de Cabeza y Cuello/tratamiento farmacológico , Adulto , Anciano , Anciano de 80 o más Años , Antimetabolitos Antineoplásicos/efectos adversos , Carcinoma de Células Escamosas/mortalidad , Carcinoma de Células Escamosas/secundario , Desoxicitidina/efectos adversos , Evaluación de Medicamentos , Femenino , Neoplasias de Cabeza y Cuello/mortalidad , Humanos , Masculino , Persona de Mediana Edad , Recurrencia Local de Neoplasia/tratamiento farmacológico , Ribonucleótido Reductasas/antagonistas & inhibidores , Tasa de Supervivencia , Gemcitabina
17.
Anticancer Res ; 21(3B): 1713-22, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-11497251

RESUMEN

This study investigated whether local delivery of 10-hydroxycamptothecin provides effective inductive chemotherapy as assessed by significant tumor reduction. Established tumorigenic human oral squamous cell carcinoma cells were used for these experiments. The experimental groups were comprised of: control (blank (no drug) poly(lactide-co-glycolide) (PLGA) microspheres), intraperitoneal 10-hydroxycamptothecin delivery + blank microspheres, local bolus 10-hydroxycamptothecin + blank microspheres, and PLGA controlled-release microspheres. The 10-hydroxycamptothecin dose administered was 12 mg/kg (bolus-intraperitoneal, local) or controlled-release over 10 days. Regardless of delivery route, 10-hydroxycamptothecin significantly reduces tumor volume. However, PLGA microspheres provide significantly higher intratumor-drug concentrations (approximately 10 and 100 fold higher) relative to local bolus and intraperitoneal routes, respectively. Also, only the PLGA microspheres significantly reduced tumor weights. Camptothecin clinical applications are limited by drug inactivation at physiological pH and the need for sustained infusions. However, due to their acidic, camptothecin-stabilizing microclimate, PLGA microspheres could provide a novel delivery system for camptothecin-based induction chemotherapy.


Asunto(s)
Antineoplásicos Fitogénicos/administración & dosificación , Antineoplásicos Fitogénicos/farmacología , Camptotecina/análogos & derivados , Camptotecina/administración & dosificación , Camptotecina/farmacología , Carcinoma de Células Escamosas/tratamiento farmacológico , Microesferas , Neoplasias de la Boca/tratamiento farmacológico , Poliglactina 910/química , Animales , Cromatografía Líquida de Alta Presión , Neoplasias de Cabeza y Cuello/tratamiento farmacológico , Humanos , Concentración de Iones de Hidrógeno , Inmunohistoquímica , Ácido Láctico/química , Pulmón/patología , Ratones , Ratones SCID , Metástasis de la Neoplasia , Trasplante de Neoplasias , Ácido Poliglicólico/química , Copolímero de Ácido Poliláctico-Ácido Poliglicólico , Polímeros/química , Factores de Tiempo , Células Tumorales Cultivadas
18.
Pharm Res ; 18(4): 488-93, 2001 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-11451036

RESUMEN

PURPOSE: Telomerase is a ribonucleoprotein that extends telomeres at the ends of chromosome. Increased telomerase activity is associated with cellular immortality. The currently available assay for telomerase, i.e., telomeric repeat amplification protocol (TRAP), consists of 2 steps: (a) telomerase-mediated extension of an oligonucleotide primer by the enzyme-containing extracts of cells and tissues, and (b) amplification of the telomerase-extended primer products by polymerase chain reaction (PCR) and detection of the PCR products. It is generally accepted that the current TRAP assay lacks quantitative precision. The present study was to develop a quantitative telomerase assay with greater precision and sensitivity. METHODS: This new method used the primer extension method as in TRAP, plus the following modifications: (a) used a lysis buffer that yielded complete lysis of nuclei; (b) removal of PCR inhibitors by phenol/chloroform extraction after primer extension; and (c) used primers for the internal standard that were designed to reduce their competition with the telomerase products for PCR. RESULTS: The modified method showed a good correlation (r2 = 0.99, P < 0.001) between telomerase amount (expressed as total protein in cell lysate) and its activity (expressed as telomerase products). Compared to the conventional TRAP, the new method (a) was more sensitive (average of 5.5-fold in cultured cancer cells and >5.9-fold in patient tumors), (b) had a lower inter- and intra-day variability (>3fold), and (c) showed a 2 to 4-fold broader range of linearity in the standard curve. The higher assay sensitivity further enabled the use of a nonradioactive method, i.e., ethidium bromide staining of DNA, to detect the TRAP products, as opposed to the use of radioactive nucleotide and the more labor-intensive autoradiography mandated by the conventional TRAP. CONCLUSION: We report here a quantitative assay for telomerase activity in cultured human cancer cells and patient tumors.


Asunto(s)
Telomerasa/metabolismo , Bioensayo/métodos , Humanos , Reacción en Cadena de la Polimerasa/métodos , Células Tumorales Cultivadas/enzimología
19.
Mutat Res ; 479(1-2): 131-9, 2001 Aug 08.
Artículo en Inglés | MEDLINE | ID: mdl-11470488

RESUMEN

Transforming growth factor-beta receptor (TbetaR)-dependent signals are critical for cell growth and differentiation and are often disrupted during tumorigenesis. The entire coding region of TbetaR-I and flanking intron sequences from 30 head and neck carcinomas were examined for alterations using "Cold" SSCP and direct sequencing. No somatic point mutations were found in the TbetaR-I gene. In contrast, 14 polymorphic sequence changes were detected in TbetaR-I in 13 (43%) of the samples, including eight (27%) nucleotide alterations identified as polymorphisms in an exon-1 (GCG)(9) microsatellite repeat, a previously reported tumor susceptibility allele. A nine base pair deletion was found in 23% of the samples including five heterozygous and two homozygous deletions as well as single homozygous 12bp deletion. Additionally, six heterozygous polymorphisms in intronic sequences were determined, including one heterozygous C/A genotype at the +82 nucleotide position of the intron-5 intervening sequence (IVS), and five heterozygous G/A genotypes within intron-7 at the +24 nucleotide position. Exon-1 polymorphisms in the (GCG)(9) microsatellite region of the TbetaR-I gene and their association with head/neck cancers, suggest that development of these cancers may be a direct consequence of loss of responsiveness to TGF-beta mediated growth inhibition.


Asunto(s)
Receptores de Activinas Tipo I/genética , Carcinoma de Células Escamosas/genética , Neoplasias de Cabeza y Cuello/genética , Mutación , Polimorfismo Genético , Receptores de Factores de Crecimiento Transformadores beta/genética , Alelos , Análisis Mutacional de ADN , Exones , Eliminación de Gen , Predisposición Genética a la Enfermedad , Genotipo , Heterocigoto , Homocigoto , Humanos , Intrones , Repeticiones de Microsatélite , Fenotipo , Reacción en Cadena de la Polimerasa , Polimorfismo Conformacional Retorcido-Simple , Proteínas Serina-Treonina Quinasas , Receptor Tipo I de Factor de Crecimiento Transformador beta
20.
Cancer Invest ; 19(2): 127-36, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-11296617

RESUMEN

From February 1993 through July 1994, 37 patients with stage III-IV squamous cell carcinomas of the oral cavity, oropharynx, or hypopharynx (stage II-IV) were registered to a treatment regimen consisting of preoperative continuous infusion cisplatin (80 mg/m2/80 hours) with hyperfractionated external beam radiotherapy (9.1 Gy/7 fractions of 1.3 Gy BID), surgical resection, intraoperative radiotherapy (7.5 Gy), and postoperative radiotherapy (40 Gy) with concurrent cisplatin (100 mg/m2 x 2 courses). The objectives of the regimen were to improve patient compliance while also increasing treatment intensity. The purpose of this article is to report the local, regional (nodal), and distant disease control of these patients after an extended time at risk (median 40 months). Overall compliance (73%), local control at primary site (97%), and regional nodal control (95%) were excellent. The rate of distant metastasis was 19%. Absolute survival at 48 months was 45.9%.


Asunto(s)
Carcinoma de Células Escamosas/cirugía , Cisplatino/uso terapéutico , Neoplasias de Cabeza y Cuello/cirugía , Carcinoma de Células Escamosas/tratamiento farmacológico , Carcinoma de Células Escamosas/mortalidad , Carcinoma de Células Escamosas/radioterapia , Quimioterapia Adyuvante/efectos adversos , Terapia Combinada/efectos adversos , Fraccionamiento de la Dosis de Radiación , Estudios de Seguimiento , Neoplasias de Cabeza y Cuello/tratamiento farmacológico , Neoplasias de Cabeza y Cuello/mortalidad , Neoplasias de Cabeza y Cuello/radioterapia , Humanos , Neoplasias Hipofaríngeas/tratamiento farmacológico , Neoplasias Hipofaríngeas/radioterapia , Neoplasias Hipofaríngeas/cirugía , Neoplasias de la Boca/tratamiento farmacológico , Neoplasias de la Boca/radioterapia , Neoplasias de la Boca/cirugía , Metástasis de la Neoplasia , Estadificación de Neoplasias , Neoplasias Orofaríngeas/tratamiento farmacológico , Neoplasias Orofaríngeas/radioterapia , Neoplasias Orofaríngeas/cirugía , Cooperación del Paciente , Dosificación Radioterapéutica , Tasa de Supervivencia , Factores de Tiempo , Resultado del Tratamiento
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