343 research outputs found

    On the preparation and X-ray data collection of isomorphous xenon derivatives

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    Brain metastases from breast cancer: prognostic significance of HER-2 overexpression, effect of trastuzumab and cause of death

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    <p>Abstract</p> <p>Background</p> <p>To access the prognostic significance of HER-2 overexpression, the effect of trastuzumab and the cause of death in patients with brain metastases (BM) from breast cancer (BC).</p> <p>Methods</p> <p>We analyzed the outcome of 130 patients with BM from BC who received whole-brain radiotherapy (WBRT) (without surgery or radiosurgery) between January 1998 and April 2006. Demographic data, tumor characteristics, and treatments were prospectively recorded. The impact of HER-2 overexpression and trastuzumab-based therapy on overall survival (OS) and the cause of death were evaluated.</p> <p>Results</p> <p>The median follow-up for the whole population was 6.25 months (mean: 9.15; range: 0.23-53). The median survival time and 1-year survival rates after BM diagnosis were 7.43 months and 35.8% (95% CI: 28-45.7) respectively. The median survival time for HER-2 negative patients (n = 78), HER-2 positive patients not treated with trastuzumab (n = 20) and HER-2 positive patients treated with trastuzumab (n = 32) were 5.9 months, 5.6 months and 19.53 months, respectively. The 1-year survival rates were 26.1%, 29.2% and 62.6% respectively, (p < 0.004). Among the 18 HER-2 positive patients treated with trastuzumab who died, 11 (61%) apparently succumbed from CNS progression, in the face of stable or responsive non-CNS disease. Trastuzumab-based therapy was associated with a 51% reduction in the risk of death (multiadjusted hazard ratio: 0.49; 95% CI, 0.29-0.83).</p> <p>Conclusions</p> <p>In our experience, trastuzumab-based therapy for HER-overexpressing tumors was associated with improved survival in BM BC patients. This subgroup of patients may benefit from innovative approaches, in order to obtain better intra cerebral control.</p

    A new paradigm for macromolecular crystallography beamlines derived from high-pressure methodology and results

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    Macromolecular crystallography at high pressure (HPMX) is a mature technique. Shorter X-ray wavelengths increase data collection efficiency on cryocooled crystals. Extending applications and exploiting spin-off of HPMX will require dedicated synchrotron radiation beamlines based on a new paradigm

    Adaptation of the base-paired double-helix molecular architecture to extreme pressure

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    The behaviour of the d(GGTATACC) oligonucleotide has been investigated by X-ray crystallography at 295 K in the range from ambient pressure to 2 GPa (∼20 000 atm). Four 3D-structures of the A-DNA form (at ambient pressure, 0.55, 1.09 and 1.39 GPa) were refined at 1.60 or 1.65 Å resolution. In addition to the diffraction pattern of the A-form, the broad meridional streaks previously explained by occluded B-DNA octamers within the channels of the crystalline A-form matrix were observed up to at least 2 GPa. This work highlights an important property of nucleic acids, their capability to withstand very high pressures, while keeping in such conditions a nearly invariant geometry of base pairs that store and carry genetic information. The double-helix base-paired architecture behaves as a molecular spring, which makes it especially adapted to very harsh conditions. These features may have contributed to the emergence of a RNA World at prebiotic stage

    Metallogenomics and biological X-ray absorption spectroscopy

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    An overview of the second special issue of the journal on biological applications of X-ray absorption spectroscopy (BioXAS) is presented. The emphasis is on the study of metalloproteins in the context of structural genomics programmes (metallo­genomics)

    High-pressure-induced water penetration into 3-­isopropylmalate dehydrogenase

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    Structures of 3-­isopropylmalate dehydrogenase were determined at pressures ranging from 0.1 to 650 MPa. Comparison of these structures gives a detailed picture of the swelling of a cavity at the dimer interface and the generation of a new cleft on the molecular surface, which are accompanied by water penetration

    Effects of the oral endothelin-receptor antagonist bosentan on echocardiographic and doppler measures in patients with pulmonary arterial hypertension

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    OBJECTIVES The purpose of this study was to investigate the effects of bosentan (125 or 250 mg twice daily) on echocardiographic and Doppler variables in 85 patients with World Health Organization class III or IV pulmonary arterial hypertension (PAH). BACKGROUND Bosentan, an orally active dual endothelin-receptor antagonist, improves symptoms, exercise capacity, and hemodynamics in patients with PAH. METHODS Patients had primary pulmonary hypertension (84%) or PAH associated with connective tissue disease. Of these, 29 patients received placebo and 56 received bosentan (1:2 randomization). Six-minute walk tests and echocardiograms were performed at baseline and after 16 weeks of treatment. RESULTS Baseline characteristics were similar in the placebo and bosentan groups, and echocardiographic and Doppler findings were consistent with marked abnormalities of right ventricular (RV) and left ventricular (LV) structure and function that were due to PAH. The treatment effect on 6-min walking distance was 37 m in favor of bosentan (p = 0.036). Treatment effects of bosentan compared with placebo on other parameters were as follows: Doppler-derived cardiac index = + 0.4 l/min/m2(p = 0.007), LV early diastolic filling velocity = + 10.5 cm/s (p = 0.003), LV end-diastolic area = + 4.2 cm2(p = 0.003), LV systolic eccentricity index = -0.12 (p = 0.047), RV end-systolic area = -2.3 cm2(p = 0.057), RV:LV diastolic areas ratio = -0.64 (p = 0.007), Doppler RV index = -0.06 (p = 0.03), and percentage of patients with an improvement in pericardial effusion score = 17% (p = 0.05). CONCLUSIONS Bosentan improves RV systolic function and LV early diastolic filling and leads to a decrease in RV dilation and an increase in LV size in patients with PAH

    Effects of the oral endothelin-receptor antagonist bosentan on echocardiographic and doppler measures in patients with pulmonary arterial hypertension

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    OBJECTIVES The purpose of this study was to investigate the effects of bosentan (125 or 250 mg twice daily) on echocardiographic and Doppler variables in 85 patients with World Health Organization class III or IV pulmonary arterial hypertension (PAH). BACKGROUND Bosentan, an orally active dual endothelin-receptor antagonist, improves symptoms, exercise capacity, and hemodynamics in patients with PAH. METHODS Patients had primary pulmonary hypertension (84%) or PAH associated with connective tissue disease. Of these, 29 patients received placebo and 56 received bosentan (1:2 randomization). Six-minute walk tests and echocardiograms were performed at baseline and after 16 weeks of treatment. RESULTS Baseline characteristics were similar in the placebo and bosentan groups, and echocardiographic and Doppler findings were consistent with marked abnormalities of right ventricular (RV) and left ventricular (LV) structure and function that were due to PAH. The treatment effect on 6-min walking distance was 37 m in favor of bosentan (p = 0.036). Treatment effects of bosentan compared with placebo on other parameters were as follows: Doppler-derived cardiac index = + 0.4 l/min/m2(p = 0.007), LV early diastolic filling velocity = + 10.5 cm/s (p = 0.003), LV end-diastolic area = + 4.2 cm2(p = 0.003), LV systolic eccentricity index = -0.12 (p = 0.047), RV end-systolic area = -2.3 cm2(p = 0.057), RV:LV diastolic areas ratio = -0.64 (p = 0.007), Doppler RV index = -0.06 (p = 0.03), and percentage of patients with an improvement in pericardial effusion score = 17% (p = 0.05). CONCLUSIONS Bosentan improves RV systolic function and LV early diastolic filling and leads to a decrease in RV dilation and an increase in LV size in patients with PAH
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