Biomedical subjects

Ana González

Publications and source records attributed to Ana González.

7 recordsLinked to original sources

PubMed2004

Docetaxel plus fractionated cisplatin is a safe and active schedule as first-line treatment of patients with advanced non-small cell lung cancer: results of a phase II study.

This phase II trial evaluated the efficacy and safety of docetaxel 85 mg/m(2) (day 1) and cisplatin 80 mg/m(2) (administered as 40 mg/m(2) doses each on days 1 and 2) every 3 weeks as first-line treatment of patients with advanced non-small cell lung cancer (NSCLC). Forty-two NSCLC patients were enrolled, most of them with stage IV disease (74%). A total of 195 chemotherapy cycles were administered (median 6, range 1-6). All patients were considered evaluable for efficacy and toxicity in an intention-to-treat (ITT) analysis. The overall response rate was 48% (95% CI, 33-64), including one CR (3%) and 19 PRs (45%). Stable disease was found in 6 patients (14%). The median time to disease progression was 4.9 months (95% CI, 4.0-5.7) and the median overall survival was 10.5 months (95% CI, 5.1-16.0). The survival rates at 1 and 2 years were 36.0% (95% CI, 19.9-52.0) and 18.0% (95% CI, 3.9-32.1), respectively. Overall, the combination showed an excellent safety profile. Severe hematological toxicities were uncommon: neutropenia (5% of patients, 1% of cycles) and febrile neutropenia (2% of patients, 0.5% of cycles). Asthenia (12%) was the only grade 3/4 non-hematological toxicity that affected more than 10% of patients. There were no toxic deaths. In conclusion, docetaxel plus fractionated cisplatin as first-line treatment of advanced NSCLC patients showed similar efficacy as the same combination with higher doses of docetaxel but where cisplatin was administered in a single dose. This new schedule shows promise in its excellent hematological and non-hematological toxicity profile. A randomized phase III trial is needed to confirm these results.

Adult↗

PubMed2003

Optimizing data collection for structure determination.

The ultimate purpose of diffraction data collection is to produce a data set which will result in the required structural information about the molecule of interest. This usually entails collecting a complete and accurate set of reflection intensities to as high a resolution as possible. In practice, the characteristics of the crystal and properties of the X-ray source can be limiting factors to the data-set quality that can be achieved and a careful strategy has to be used to extract the maximum amount of information from the data within the experimental constraints. In the particular case of data intended for phasing using anomalous dispersion, the synchrotron beamline properties are relevant to determine how many wavelengths (one or more) should be used for the experiment and what the wavelength values should be. This will in turn affect the detailed strategy for data collection, including decisions about the data-collection sequence and how much data to collect at each wavelength. Collection of multiwavelength anomalous dispersion (MAD) data at three different wavelengths can provide very accurate experimental phases. Two-wavelength MAD experiments may offer the best compromise between phase quality and minimizing the effects of radiation damage to the sample. However, MAD experiments are demanding in terms of beamline wavelength range, easy tunability, stability and reproducibility. When the beamline cannot fulfill these demands, single-wavelength experiments may be a better option.

Crystallography, X-Ray↗

PubMed2003

The 0.93A crystal structure of sphericase: a calcium-loaded serine protease from Bacillus sphaericus.

We have previously isolated sphericase (Sph), an extracellular mesophilic serine protease produced by Bacillus sphaericus. The Sph amino acid sequence is highly homologous to two cold-adapted subtilisins from Antarctic bacilli S39 and S41 (76% and 74% identity, respectively). Sph is calcium-dependent, 310 amino acid residues long and has optimal activity at pH 10.0. S41 and S39 have not as yet been structurally analysed. In the present work, we determined the crystal structure of Sph by the Eu/multiwavelength anomalous diffraction method. The structure was extended to 0.93A resolution and refined to a crystallographic R-factor of 9.7%. The final model included all 310 amino acid residues, one disulfide bond, 679 water molecules and five calcium ions. Although Sph is a mesophilic subtilisin, its amino acid sequence is similar to that of the psychrophilic subtilisins, which suggests that the crystal structure of these subtilisins is very similar. The presence of five calcium ions bound to a subtilisin molecule, as found here for Sph, has not been reported for the subtilisin superfamily. None of these calcium-binding sites correlates with the well-known high-affinity calcium-binding site (site I or site A), and only one site has been described previously. This calcium-binding pattern suggests that a reduction in the flexibility of the surface loops of Sph by calcium binding may be responsible for its adaptation to mesophilic organisms.

Amino Acid Sequence↗

PubMed2003

Structure of Rhodoferax fermentans high-potential iron-sulfur protein solved by MAD.

The crystal structure of Rhodoferax fermentans high-potential iron protein (HiPIP) has been solved by MAD methods using the anomalous signal from the Fe atoms in the [Fe(4)S(4)] cluster present in the protein and refined to a resolution of 1.45 A. The peptide chain is well defined except in the N- and C-terminal areas. The structure of the protein reveals the presence of three helical fragments, a small beta-sheet and several turns, with the [Fe(4)S(4)] cluster being located close to a surface patch containing several well conserved aromatic residues. The protein fold is very similar to the structures of other known HiPIPs, especially in the region proximal to the [Fe(4)S(4)] cluster, while the largest differences are observed on the opposite side of the protein, which is rich in positive charges and has no sequential homology to other HiPIP families.

Bacterial Proteins↗

PubMed2003

Faster data-collection strategies for structure determination using anomalous dispersion.

Many macromolecular structures are being determined using anomalous dispersion phasing methods. Different data-collection strategies at one, two, three or more wavelengths can be used for these experiments. The choice of strategy can determine the success or failure of the experiment and should be based on a clear understanding of the advantages and disadvantages of each approach given the experimental constraints and goals. In this paper, several sets of three-wavelength MAD experiment data were reanalyzed using one, two and three wavelengths and systematically removing reflections from the data sets to determine the minimum amount of data required to yield an automatically traceable map as a function of the number of wavelengths used in phasing. In the cases studied here, two-wavelength MAD consistently required fewer data than three-wavelength MAD, as long as the unique data completeness was high at each wavelength. It was also found in some instances that using one wavelength for phasing required as much or more data as using two wavelengths. These results can help with the design of adequate data-collection strategies which maximize the phasing power from the minimal data collected. This is particularly important for minimizing the effects of radiation damage on phasing while taking sample characteristics, beamline properties and experimental goals into account.

Crystallography, X-Ray↗

PubMed2003

Rapid progression of midventricular obstruction in adults with double-chambered right ventricle.

OBJECTIVE: The purpose of this study was to determine the rate of progression of midventricular obstruction in adolescents and adults with double-chambered right ventricle. METHODS: Clinical and echocardiographic findings in 45 patients (mean age 26 +/- 6 years, range 15-44) diagnosed with double-chambered right ventricle were retrospectively analyzed. Twenty patients underwent surgical repair before the age of 15 years. The relationship between Doppler midventricular pressure gradient and patient age was analyzed in 25 patients without previous repair. Sequential change in midventricular obstruction was determined for patients with 2 or more Doppler echocardiographic examinations performed within at least a 2-year interval. RESULTS: Right midventricular pressure gradient in nonrepaired patients was 70 +/- 38 mm Hg (range 25-150). A significant relationship between midventricular obstruction and patient age (r = 0.64, P <.001) was found. Midventricular pressure gradient at initial evaluation was 32 +/- 27 mm Hg in 16 patients < 25 years and 73 +/- 45 mm Hg in 9 patients >/= 25 years (P <.03). After the initial study, 5 patients underwent surgical repair and 13 patients without repair were followed up for a period of 6.1 +/- 2.7 years (range 2-9), in which midventricular pressure gradient increased from 32 +/- 26 mm Hg to 67 +/- 35 mm Hg (P <.001). The slope of the change in midventricular pressure gradient was 6.2 +/- 3 mm Hg per year of follow-up. Seven more patients underwent surgical repair during follow-up due to progression of the obstruction. There was no mortality nor residual midventricular obstruction in surgically repaired patients. CONCLUSIONS: Mild right midventricular obstruction shows a fast rate of progression in adolescents and young adults. Thus, close clinical and echocardiographic follow-up is advised, and surgical repair should be considered if significant progression of obstruction is detected.

Adolescent↗

PubMed2002

Predisposing conditions for atrial fibrillation in atrial septal defect with and without operative closure.

The aims of this study were to determine the prevalence and predisposing conditions for atrial fibrillation (AF) in adults with atrial septal defect (ASD) and to evaluate the influence of age at surgical repair. The study population consisted of 286 adults with ASD (mean age 39.5 +/- 19 years). All patients had >or = 1 follow-up visit and a Doppler echocardiographic study. One hundred ninety-two of the patients underwent surgical closure 1 to 34 years before the study. Analyzed variables were entered into univariate (Mann-Whitney U) and multivariate (stepwise logistic regression) models to assess independent predictors for AF. The prevalence of AF was similar in surgically treated patients (15.6%) and in the nonsurgical group (13.8%) (p = 0.69). Multivariate analysis showed that current age (RR 1.9 per each decade of age, 95% confidence interval [CI] 1.3 to 2.7, p = 0.001), mitral regurgitation (RR 3.0 per each degree of regurgitation, 95% CI 1.6 to 5.8, p = 0.001), left atrial enlargement (RR 2.8 per each 10 mm increase in size, 95% CI 1.5 to 5.2, p = 0.001), and tricuspid regurgitation (RR 1.9 per each degree of regurgitation, 95% CI 1.0 to 3.7, p = 0.04) were independent predictors of AF; however, gender, anatomic type, defect size, Qp:Qs, pulmonary artery pressure, right ventricular dimension, left ventricular shortening fraction, and prior surgical repair were not related to late AF development. In the surgical group, age >25 years at the time of surgery was the only predictor for AF independent of age at the time of the study (p = 0.02).

Adolescent↗