Supernova Hosts for Gamma-Ray Burst Jets: Dynamical Constraints

I constrain a possible supernova origin for gamma-ray bursts by modeling the dynamical interaction between a relativistic jet and a stellar envelope surrounding it. The delay in observer's time introduced by the jet traversing the envelope should not be long compared to the duration of gamma-ray emission; also, the jet should not be swallowed by a spherical explosion it powers. The only stellar progenitors that comfortably satisfy these constraints, if one assumes that jets move ballistically within their host stars, are compact carbon-oxygen or helium post-Wolf-Rayet stars (type Ic or Ib supernovae); type II supernovae are ruled out. Notably, very massive stars do not appear capable of producing the observed bursts at any redshift unless the stellar envelope is stripped prior to collapse. The presence of a dense stellar wind places an upper limit on the Lorentz factor of the jet in the internal shock model; however, this constraint may be evaded if the wind is swept forward by a photon precursor. Shock breakout and cocoon blowout are considered individually; neither presents a likely source of precursors for cosmological GRBs. These envelope constraints could conceivably be circumvented if jets are laterally pressure-confined while traversing the outer stellar envelope. If so, jets responsible for observed GRBs must either have been launched from a region several hundred kilometers wide, or have mixed with envelope material as they travel. A phase of pressure confinement and mixing would imprint correlations among jets that may explain observed GRB variability-luminosity and lag-luminosity correlations.Comment: 17 pages, MNRAS, accepted. Contains new analysis of pressure-confined jets, of jets that experience oblique shocks or mix with their cocoons, and of cocoons after breakou

Valor clínico de la tomografía de emisión de positrones con F-18-FDG en el seguimiento de pacientes con cáncer de ovario

Background. Positron emission tomography with fluor- 18-deoxyglucose (PET-FDG) is an efficient technique for the detection of tumoural tissue. The aim of the paper is to evaluate the PET-FDG in the diagnosis of residual disease or relapse in patients with cancer of the ovary. Methods. A total of 24 patients, diagnosed and treated for cancer of the ovary with surgery and subsequent chemotherapy, were included. With 12 patients the study was carried out prior to second-look surgery, and with the other 12 after objectivising an increase of the tumoural marker in the follow up. Abdominal-pelvic CAT, determination of the seric levels of CA-125 and PET-FDG of thorax, abdomen and pelvis were carried out on all patients. The PET-FDG was evaluated in a qualitative way through the visual study of the images, and quantitatively through the SUV or standard uptake value. The definitive diagnosis was confirmed through an anatomopathological study in 13 cases and through clinical follow up in the rest with an average of 11.2±5.4 months (range 6-24). Results. A CA-125 value higher than 35 UI/ml was considered positive, obtaining a sensitivity of 77% and a specificity of 100%. The sensitivity of the CAT was 23% and the specificity 91%. With the FDG-PET sensitivity was 92% and the specificity 90%. A SUV value ≥ 3 was considered pathological, obtaining the same results as with the visual evaluation. The FDG-PET was positive in 5 patients with non-conclusive CAT, 4 with negative CAT and 2 with negative CA-125. Conclusion. These preliminary results suggest that the FDG-PET could be useful in the follow up of patients treated for cancer of the ovary. The FDG-PET could be efficient in the differentiation between residual disease or recurrence, as opposed to sequels to the treatment, when the CAT is not conclusive due to anatomical distortion. The FDG-PET could be more sensitive than an increased marker value, and facing an increase of the latter it permits a non-invasive localisation of the disease

Double balloon catheter for induction of labour in women with a previous cesarean section, could it be the best choice?

Introduction: We analysed the efficacy and safety of double-balloon catheter for cervical ripening in women with a previous cesarean section and which were the most important variables associated with an increased risk of repeated cesarean delivery. Materials and methods: We designed an observational retrospective study of 418 women with unfavourable cervices (Bishop Score <5), a prior cesarean delivery, and induction of labour with a double-balloon catheter. Baseline maternal data and perinatal outcomes were recorded for a descriptive, bivariate, and multivariate analysis. A p value <0.05 was considered statistically significant. Results: Most women improved their initial Bishop Score (89.5%) although only a 20.8% of them went into spontaneous active labour. Finally, 51.4% of the women achieved a vaginal delivery. Five cases of intrapartum uterine rupture (1.2%) occurred. After multivariate analysis, main risk factors for repeated cesarean section were dystocia in the previous pregnancy (OR 1.744; CI 95% 1.066–2.846), the absence of previous vaginal delivery (OR 2.590; CI 95% 1.066–6.290), suspected fetal macrosomia (OR 2.410; CI 95% 0.959–6.054), and duration of oxytocin induction period (OR 1.005; CI 95% 1.004–1.006). The area under the curve was 0.789 (p < 0.001). Conclusions: Double-balloon catheter seems to be safe and effective for cervical ripening in women with a previous cesarean delivery and unfavourable cervix. In our study, most women could have a vaginal delivery in spite of their risk factors for cesarean delivery. A multivariate model based on some clinical variables has moderate predictive value for intrapartum cesarean section

Core-shifts and proper-motion constraints in the S5 polar cap sample at the 15 and 43 GHz bands

We have studied a complete radio sample of active galactic nuclei with the very-long-baseline-interferometry (VLBI) technique and for the first time successfully obtained high-precision phase-delay astrometry at Q band (43 GHz) from observations acquired in 2010. We have compared our astrometric results with those obtained with the same technique at U band (15 GHz) from data collected in 2000. The differences in source separations among all the source pairs observed in common at the two epochs are compatible at the 1σ level between U and Q bands. With the benefit of quasi-simultaneous U and Q band observations in 2010, we have studied chromatic effects (core-shift) at the radio source cores with three different methods. The magnitudes of the core-shifts are of the same order (about 0.1 mas) for all methods. However, some discrepancies arise in the orientation of the core-shifts determined through the different methods. In some cases these discrepancies are due to insufficient signal for the method used. In others, the discrepancies reflect assumptions of the methods and could be explained by curvatures in the jets and departures from conical jets

The Mediterranean diet protects against waist circumference enlargement in 12Ala carriers for the PPARgamma gene: 2 years' follow-up of 774 subjects at high cardiovascular risk.

The PPARgamma gene regulates insulin sensitivity and adipogenesis. The Pro12Ala polymorphism of this gene has been related to fat accumulation. Our aim was to analyse the effects of a 2-year nutritional intervention with Mediterranean-style diets on adiposity in high-cardiovascular risk patients depending on the Pro12Ala polymorphism of the PPARgamma gene. The population consisted of a substudy (774 high-risk subjects aged 55-80 years) of the Prevención con Dieta Mediterránea (PREDIMED) randomised trial aimed at assessing the effect of the Mediterranean diet for CVD prevention. There were three nutritional intervention groups: two of them of a Mediterranean-style diet and the third was a control group advised to follow a conventional low-fat diet. All the participants were genotyped by PCR-restriction fragment length polymorphism (RFLP). The results showed that carriers of the 12Ala allele allocated to the control group had a statistically significant higher change in waist circumference (adjusted difference coefficient = 2.37 cm; P = 0.014) compared with wild-type subjects after 2 years of nutritional intervention. This adverse effect was not observed among 12Ala carriers allocated to both Mediterranean diet groups. In diabetic patients a statistically significant interaction between Mediterranean diet and the 12Ala allele regarding waist circumference change was observed ( - 5.85 cm; P = 0.003). In conclusion, the Mediterranean diet seems to be able to reduce waist circumference in a high-cardiovascular risk population, reversing the negative effect that the 12Ala allele carriers of the PPARgamma gene appeared to have. The beneficial effect of this dietary pattern seems to be higher among type 2 diabetic subjects

Correlaciones entre la SPECT cerebral y la evaluación neuropsicológica en los estadios leve y moderado de la enfermedad de Alzheimer

Se evaluaron 34 pacientes con enfermedad de Alzheimer (EA) probable (EA leve = 16; EA moderada = 18) y 12 controles mediante un estudio semicuantitativo de SPECT con 99mTc-HMPAO y la batería de tests neuropsicológicos CERAD. Resultados: La hipoperfusión temporal (p < 0,01) y los tests de memoria (p < 0,001) permitieron diferenciar los controles de los pacientes con EA leve. En estos pacientes se observaron también correlaciones significativas (p < 0,05) entre: test de recuerdo diferido-hipoperfusión temporal, test de aprendizaje-hipoperfusión temporoparietal y frontal y praxis visuoconstructiva-hipoperfusión temporal posterior. Los pacientes con EA moderada mostraron, respecto a la EA leve, una mayor hipoperfusión temporal (p < 0,01), parietal y frontal (p < 0,05), junto a un empeoramiento de la praxis (p < 0,001) y los test de memoria (p < 0,05). Conclusiones: La SPECT y la evaluación neuropsicológica permiten distinguir entre controles y pacientes con estadios leve y moderado de la EA, existiendo una estrecha correlación entre ambos métodos desde las etapas iniciales de la enfermedad

Impact of the dosimetry approach on the resulting 90Y radioembolization planned absorbed doses based on 99mTc-MAA SPEC T-CT: is there agreement between dosimetry methods?

Background: Prior radioembolization, a simulation using 99mTc-macroaggregated albumin as 90Y-microspheres surrogate is performed. Gamma scintigraphy images (planar, SPECT, or SPECT-CT) are acquired to evaluate intrahepatic 90Y-microspheres distribution and detect possible extrahepatic and lung shunting. These images may be used for pre-treatment dosimetry evaluation to calculate the 90Y activity that would get an optimal tumor response while sparing healthy tissues. Several dosimetry methods are available, but there is still no consensus on the best methodology to calculate absorbed doses. The goal of this study was to retrospectively evaluate the impact of using different dosimetry approaches on the resulting 90Y-radioembolization pre-treatment absorbed dose evaluation based on 99mTc-MAA images. Methods: Absorbed doses within volumes of interest resulting from partition model (PM) and 3D voxel dosimetry methods (3D-VDM) (dose-point kernel convolution and local deposition method) were evaluated. Additionally, a new “Multi-tumor Partition Model” (MTPM) was developed. The differences among dosimetry approaches were evaluated in terms of mean absorbed dose and dose volume histograms within the volumes of interest. Results: Differences in mean absorbed dose among dosimetry methods are higher in tumor volumes than in non-tumoral ones. The differences between MTPM and both 3D-VDM were substantially lower than those observed between PM and any 3D-VDM. A poor correlation and concordance were found between PM and the other studied dosimetry approaches. DVH obtained from either 3D-VDM are pretty similar in both healthy liver and individual tumors. Although no relevant global differences, in terms of absorbed dose in Gy, between both 3D-VDM were found, important voxel-by-voxel differences have been observed. Conclusions: Significant differences among the studied dosimetry approaches for 90Y-radioembolization treatments exist. Differences do not yield a substantial impact in treatment planning for healthy tissue but they do for tumoral liver. An individual segmentation and evaluation of the tumors is essential. In patients with multiple tumors, the application of PM is not optimal and the 3D-VDM or the new MTPM are suggested instead. If a 3D-VDM method is not available, MTPM is the best option. Furthermore, both 3D-VDM approaches may be indistinctly used

Disminución de la reserva de flujo coronario en pacientes con insuficiencia cardíaca no isquémica

Introduction and objectives. Coronary flow reserve (CFR) is impaired not only in ischemic heart disease, but also in cardiac diseases that may or may not course with heart failure. The aim of the present study was to determine if the severity of heart failure can influence CFR impairment. Methods. Forty patients with non-ischemic heart disease and heart failure were studied 41 times. Four groups were established: 1. 10 patients in functional class III-IV; 2. 10 patients in functional class II not taking beta-blockers; 3. 11 patients in class II treated with carvedilol, and 4. 10 patients in class I. These patients had a history of heart failure and systolic dysfunction. Myocardial blood flow (MBF) was measured with positron emission tomography (PET) and N-13 ammonia at rest (r) and during adenosine triphosphate (ATP) infusion. Results. MBF and CFR were significantly higher in group 4 (1.95 ± 0.58 and 2.40 ± 0.95 ml/min/g) than in group 1 (1.02 ± 0.52 and 1.46 ± 0.48 ml/min/g). CFR tended to be higher in groups 2 (1.73 ± 0.72), and 3 (1.89 ± 0.75) vs group 1. No significant correlation was found between CFR and the following variables: age, systolic blood pressure, ventricular mass index, ventricular volume indexes, and ejection fraction. Conclusions. Coronary microvascular function is impaired in non-ischemic heart failure, and the impairment is related to functional class, regardless of the underlying responsible heart disease