Impact and control of the COVID pandemic in an elite sports club: Real Madrid.

The incidence and risk factors for poor outcome in patients with COVID are well known, as are the protective measures in high-risk populations. In contrast, the epidemiological and clinical behavior of this disease in the population of elite athletes who are the paradigm of good health is poorly understood. Data on COVID in athletes are scarce and have focused preferentially on the consequences on sports performance of confinement measures and on the pathophysiological risks of infected athletes. Real Madrid is a large elite sports institution with facilities in the City of Madrid where 600 athletes train daily. The incidence of COVID during a study period of 671 days of observation in athletes, professional or amateur, working in the institution has been 0,74 per 1,000 days of exposure. The disease has been asymptomatic or oligosymptomatic in all athletes and did not require any hospital admissions. The different teams did not have to suspend any of its sportive commitments for COVID during the study period and there was no evidence of outbreaks of internal transmission between members of the different teams.

The Madrid-2019 force field for electrolytes in water using TIP4P/2005 and scaled charges: Extension to the ions F-, Br-, I-, Rb+, and Cs.

In this work, an extension of the Madrid-2019 force field is presented. We have added the cations Rb+ and Cs+ and the anions F-, Br-, and I-. These ions were the remaining alkaline and halogen ions, not previously considered in the Madrid-2019 force field. The force field, denoted as Madrid-2019-Extended, does not include polarizability and uses the TIP4P/2005 model of water and scaled charges for the ions. A charge of ±0.85e is assigned to monovalent ions. The force field developed provides an accurate description of aqueous solution densities over a wide range of concentrations up to the solubility limit of each salt studied. Good predictions of viscosity and diffusion coefficients are obtained for concentrations below 2 m. Structural properties obtained with this force field are also in reasonable agreement with the experiment. The number of contact ion pairs has been controlled to be low so as to avoid precipitation of the system at concentrations close to the experimental solubility limit. A comprehensive comparison of the performance for aqueous solutions of alkaline halides of force fields of electrolytes using scaled and integer charges is now possible. This comparison will help in the future to learn about the benefits and limitations of the use of scaled charges to describe electrolyte solutions.

A force field of Li+, Na+, K+, Mg2+, Ca2+, Cl-, and SO4 2- in aqueous solution based on the TIP4P/2005 water model and scaled charges for the ions.

In this work, a force field for several ions in water is proposed. In particular, we consider the cations Li+, Na+, K+, Mg2+, and Ca2+ and the anions Cl- and SO4 2-. These ions were selected as they appear in the composition of seawater, and they are also found in biological systems. The force field proposed (denoted as Madrid-2019) is nonpolarizable, and both water molecules and sulfate anions are rigid. For water, we use the TIP4P/2005 model. The main idea behind this work is to further explore the possibility of using scaled charges for describing ionic solutions. Monovalent and divalent ions are modeled using charges of 0.85 and 1.7, respectively (in electron units). The model allows a very accurate description of the densities of the solutions up to high concentrations. It also gives good predictions of viscosities up to 3 m concentrations. Calculated structural properties are also in reasonable agreement with the experiment. We have checked that no crystallization occurred in the simulations at concentrations similar to the solubility limit. A test for ternary mixtures shows that the force field provides excellent performance at an affordable computer cost. In summary, the use of scaled charges, which could be regarded as an effective and simple way of accounting for polarization (at least to a certain extend), improves the overall description of ionic systems in water. However, for purely ionic systems, scaled charges will not adequately describe neither the solid nor the melt.

Health-related quality of life in men with prostate cancer undergoing active surveillance versus radical prostatectomy, external-beam radiotherapy, prostate brachytherapy and reference population: a cross-sectional study.

BACKGROUND: The purpose of this study is to describe Health-Related Quality of Life (HRQoL) of localized prostate cancer patients in an Active Surveillance (AS) program, and to compare them with those undergoing radical prostatectomy (RP), external-beam radiotherapy (XRT) and brachytherapy (BT). METHODS: Multi-institutional pooled cross-sectional analysis on patients in an AS protocol: < 75 years old; pathologically confirmed LPC (maximum of three positive cylinders); Gleason score < 3 + 4; clinical stage T1a-T2b; and PSA < 15 ng/ml. Exclusion criteria for this study were: less than 6 months in AS, termination of AS protocol, or incomplete data. Patients in AS were matched with those treated with RP, XRT or BT from the 'Spanish Multicentric Study of Clinically Localized Prostate Cancer' cohort according to risk group, time from treatment selection to HRQoL survey, and age. Prostate-specific (EPIC) and generic (SF-36) HRQoL instruments were completed. Analysis was stratified by HRQoL survey moment (>or < 2.5 years from treatment selection), and age (>or < 70 years old). RESULTS: Median of time from treatment selection to HRQoL survey in the total 396 patients (99 per treatment group) was 2.4 years (range 0.5-8.3). Patients in AS presented higher (better) urinary incontinence scores than RP ones in both stratus of time from treatment selection to HRQoL survey (92.6 vs 67.0 and 81.4 vs 64.4, p <  0.01). Patients in AS for < 2.5 years presented greater sexual scores than any active treatment (p <  0.01), but only statistically higher than RP for those in AS for longer than 2.5 years. The magnitude of the differences between AS and RP groups in both EPIC domains ranged from moderate (0.7 SD) to large (1.0 SD). Regardless of treatment applied, patients presented similar and slightly increased SF-36 scores than US general population reference norms. Nonetheless, patients in AS for < 2.5 years reported worse outcomes than other treatment groups on physical health domains, especially in bodily pain (0.5-0.6 SD), and vitality (0.6-0.8 SD). CONCLUSIONS: Considering patients' well-being, AS can be a good therapeutic option due to the low impact caused on urinary continence and sexual function. However, longitudinal studies are required to take into account HRQoL evolution over time.

A potential model for sodium chloride solutions based on the TIP4P/2005 water model.

Despite considerable efforts over more than two decades, our knowledge of the interactions in electrolyte solutions is not yet satisfactory. Not even one of the most simple and important aqueous solutions, NaCl(aq), escapes this assertion. A requisite for the development of a force field for any water solution is the availability of a good model for water. Despite the fact that TIP4P/2005 seems to fulfill the requirement, little work has been devoted to build a force field based on TIP4P/2005. In this work, we try to fill this gap for NaCl(aq). After unsuccessful attempts to produce accurate predictions for a wide range of properties using unity ionic charges, we decided to follow recent suggestions indicating that the charges should be scaled in the ionic solution. In this way, we have been able to develop a satisfactory non-polarizable force field for NaCl(aq). We evaluate a number of thermodynamic properties of the solution (equation of state, maximum in density, enthalpies of solution, activity coefficients, radial distribution functions, solubility, surface tension, diffusion coefficients, and viscosity). Overall the results for the solution are very good. An important achievement of our model is that it also accounts for the dynamical properties of the solution, a test for which the force fields so far proposed failed. The same is true for the solubility and for the maximum in density where the model describes the experimental results almost quantitatively. The price to pay is that the model is not so good at describing NaCl in the solid phase, although the results for several properties (density and melting temperature) are still acceptable. We conclude that the scaling of the charges improves the overall description of NaCl aqueous solutions when the polarization is not included.

Exploitation of temporal redundancy in compressed sensing reconstruction of fMRI studies with a prior-based algorithm (PICCS).

PURPOSE: Compressed sensing is a technique used to accelerate magnetic resonance imaging (MRI) acquisition without compromising image quality. While it has proven particularly useful in dynamic imaging procedures such as cardiac cine, very few authors have applied it to functional magnetic resonance imaging (fMRI). The purpose of the present study was to check whether the prior image constrained compressed sensing (PICCS) algorithm, which is based on an available prior image, can improve the statistical maps in fMRI better than other strategies that also exploit temporal redundancy. METHODS: PICCS was compared to spatiotemporal total variation (TTV) and k-t FASTER, since they have already demonstrated high performance and robustness in other MRI applications, such as cardiac cine MRI and resting state fMRI, respectively. The prior image for PICCS was the average of all undersampled data. Both PICCS and TTV were solved using the split Bregman formulation. K-t FASTER algorithm relies on matrix completion to reconstruct the undersampled k-spaces. The three algorithms were evaluated using two datasets with high and low signal-to-noise ratio (SNR)-BOLD contrast-acquired in a 7 T preclinical MRI scanner and retrospectively undersampled at various rates (i.e., acceleration factors). The authors evaluated their performance in terms of the sensitivity/specificity of BOLD detection through receiver operating characteristic curves and by visual inspection of the statistical maps. RESULTS: With high SNR studies, PICCS performed similarly to the state-of-the-art algorithms TTV and k-t FASTER and provided consistent BOLD signal at the ROI. In scenarios with low SNR and high acceleration factors, PICCS still provided consistent maps and higher sensitivity/specificity than TTV, whereas k-t FASTER failed to provide significant maps. CONCLUSIONS: The authors performed a comparison between three reconstructions (PICCS, TTV, and k-t FASTER) that exploit temporal redundancy in fMRI. The prior-based algorithm, PICCS, preserved BOLD activation and sensitivity/specificity better than TTV and k-t FASTER in noisy scenarios. The PICCS algorithm can potentially reach an acceleration factor of ×8 and still provide BOLD contrast in the ROI with an area under the curve over 0.99.

Nucleation free-energy barriers with Hybrid Monte-Carlo/Umbrella Sampling.

The aim of this work is to evaluate nucleation free-energy barriers using molecular dynamics (MD). More specifically, we use a combination of Hybrid Monte Carlo (HMC) and an Umbrella Sampling scheme, and compute the crystallisation barrier of NaCl from its melt. Firstly the convergence and performance of HMC for different time-steps and the number of MD steps within a HMC cycle are assessed. The calculated potential energies and densities converge regardless of the chosen time-step. However the acceptance ratio of the Metropolis step within the HMC scheme strongly depends on the time-step and affects the performance. It is shown that the acceptance ratio is close to 100% for time-steps of the order of those commonly used in molecular dynamics runs. We then explore the results obtained with a "non-Metropolised" version of HMC where the MD trajectories are always accepted (omitting the Metropolis criteria) and conclude that they are satisfactory for time-steps below 5 fs. Next, HMC is combined with Umbrella Sampling (HMC/US) to compute the nucleation free-energy for both the standard and the "non-Metropolised" HMC (using a small time-step) and in both cases find excellent agreement with the reported values. To conclude, we explore approximations to the HMC/US technique implementing HMC with isothermal-isobaric MD trajectories. The computed nucleation free-energy curve is coincident, within the statistical error, with previous calculations.

Determining the phase diagram of water from direct coexistence simulations: the phase diagram of the TIP4P/2005 model revisited.

Direct coexistence simulations between the fluid and solid phases are performed for several ices. For ices Ih and VII it has already been shown that the methodology is successful and the melting point is in agreement with that obtained from free energy calculations. In this work the methodology is applied to ices II, III, V, and VI. The lengths of the direct coexistence runs for the high pressure polymorphs are not too long and last less than 20 ns for all ices except for ice II where longer runs (of about 150 ns) are needed. For ices II, V, and VI the results obtained are completely consistent with those obtained from free energy calculations. However, for ice III it is found that the melting point from direct coexistence simulations is higher than that obtained from free energy calculations, the difference being greater than the statistical error. Since ice III presents partial proton orientational disorder, the departure is attributed to differences in the partial proton order in the water model with respect to that found in the experiment. The phase diagram of the TIP4P/2005 model is recalculated using the melting points obtained from direct coexistence simulations. The new phase diagram is similar to the previous one except for the coexistence lines where ice III is involved. The range of stability of ice III on the p-T plot of the phase diagram increases significantly. It is seen that the model qualitatively describes the phase diagram of water. In this work it is shown that the complete phase diagram of water including ices Ih, II, III, V, VI, VII, and the fluid phase can be obtained from direct coexistence simulations without the need of free energy calculations.

Homogeneous ice nucleation at moderate supercooling from molecular simulation.

Among all of the freezing transitions, that of water into ice is probably the most relevant to biology, physics, geology, or atmospheric science. In this work, we investigate homogeneous ice nucleation by means of computer simulations. We evaluate the size of the critical cluster and the nucleation rate for temperatures ranging between 15 and 35 K below melting. We use the TIP4P/2005 and the TIP4P/ice water models. Both give similar results when compared at the same temperature difference with the model's melting temperature. The size of the critical cluster varies from ∼8000 molecules (radius = 4 nm) at 15 K below melting to ∼600 molecules (radius = 1.7 nm) at 35 K below melting. We use Classical Nucleation Theory (CNT) to estimate the ice-water interfacial free energy and the nucleation free-energy barrier. We obtain an interfacial free energy of 29(3) mN/m from an extrapolation of our results to the melting temperature. This value is in good agreement both with experimental measurements and with previous estimates from computer simulations of TIP4P-like models. Moreover, we obtain estimates of the nucleation rate from simulations of the critical cluster at the barrier top. The values we get for both models agree within statistical error with experimental measurements. At temperatures higher than 20 K below melting, we get nucleation rates slower than the appearance of a critical cluster in all water of the hydrosphere during the age of the universe. Therefore, our simulations predict that water freezing above this temperature must necessarily be heterogeneous.

Fluorescence diffuse optical tomography using the split Bregman method.

PURPOSE: Standard image reconstruction methods for fluorescence Diffuse Optical Tomography (fDOT) generally make use of L2-regularization. A better choice is to replace the L2 by a total variation functional that effectively removes noise while preserving edges. Among the wide range of approaches available, the recently appeared Split Bregman method has been shown to be optimal and efficient. Furthermore, additional constraints can be easily included. We propose the use of the Split Bregman method to solve the image reconstruction problem for fDOT with a nonnegativity constraint that imposes the reconstructed concentration of fluorophore to be positive. METHODS: The proposed method is tested with simulated and experimental data, and results are compared with those yielded by an equivalent unconstrained optimization approach based on Gauss-Newton (GN) method, in which the negative part of the solution is projected to zero after each iteration. In addition, the method dependence on the parameters that weigh data fidelity and nonnegativity constraints is analyzed. RESULTS: Split Bregman yielded a reduction of the solution error norm and a better full width at tenth maximum for simulated data, and higher signal-to-noise ratio for experimental data. It is also shown that it led to an optimum solution independently of the data fidelity parameter, as long as the number of iterations is properly selected, and that there is a linear relation between the number of iterations and the inverse of the data fidelity parameter. CONCLUSIONS: Split Bregman allows the addition of a nonnegativity constraint leading to improve image quality.

Diagnóstico fotodinámico con hexaminolevulinato en el cáncer vesical no músculo invasivo: experiencia del grupo BLUE / Hexaminolevulinate photodynamic diagnosis in non-muscle invasive bladder cancer: experience of the BLUE group

Objetivos: El diagnóstico fotodinámico (DFD) con hexaminolevulinato se ha empezado a utilizar recientemente para mejorar la detección del cáncer vesical no músculo invasivo. Nuestro objetivo principal fue comparar el rendimiento diagnóstico de DFD frente a endoscopia con luz blanca convencional (LB) en nuestro medio. Material y métodos: Se realizó cistoscopia fluorescente con hexaminolevulinato en el momento de la RTU a 305 pacientes de 7 hospitales españoles. Todas las lesiones detectadas con LB y DFD fueron enumeradas y registradas en una base de datos online. Se analizó histopatológicamente cada lesión por separado. En 148 pacientes se tomaron además biopsias múltiples aleatorias (BMA). Resultados: Se biopsiaron un total de 1.659 lesiones: 522 identificadas con DFD y LB, 237 sólo con DFD, 19 sólo con LB y 881 BMA. De 600 neoplasias diagnosticadas DFD detectó 563, LB 441 y BMA 29 (20 CIS). La tasa media de sobredetección de DFD sobre LB fue del 31,9% globalmente, pero en el caso del CIS fue del 209%. La sensibilidad de DFD fue 93,8% y la de LB 78,2%. La especificidad de DFD fue 81,5% y la de LB 90,5%. En el 23% de los pacientes se detectó al menos una lesión neoplásica más con DFD que con LB. Conclusión: La RTU con hexaminolevulinato mejora el rendimiento diagnóstico y la calidad de la resección del cáncer vesical superficial, especialmente del CIS. La mayor sensibilidad de DFD es a costa de una menor especificidad. En nuestro estudio BMA rescató algunos falsos negativos de DFD para detectar CIS (AU)

Objectives: Photodynamic diagnosis (PDD) with hexaminolevulinate has been recently used to improve detection of non-muscle invasive bladder cancer. Our main purpose was to quantify the benefit of PDD vs. conventional white light cystoscopy (WL) in our area. Material and methods: Fluorescence-guided cystoscopy using hexaminolevulinate was performed at the time of the transurethral resection (TUR) in 305 patients from 7 Spanish hospitals. All lesions found with WL and PDD were numbered and recorded in an online database. Each lesion was sent separately for pathology analysis. Random biopsies were also obtained in 148 patients. Results: A total of 1659 lesions were biopsied: 522 were identified with PDD and WL, 237 only with PDD, 19 only with WL and 881 random biopsies. Of the 600 tumors, PDD detected 563, WL 441 and random biopsies 29 (20 CIS). The mean overdetection rate for PDD over WL was 31.9% for all types of lesions, but it was 209% for carcinoma in situ (CIS). Sensitivity was 93.8% for PDD and 78.2% for WL. Specificity was 81.5% for PDD and 90.5% for WL. In 23% of patients, PDD detected at least one additional neoplastic lesion compared to WL. Conclusions: Hexaminolevulinate fluorescence cystoscopy improves detection and resection of non-muscle invasive bladder cancer, especially of CIS. Sensitivity of PDD is higher than WL, but specificity is lower. In our study, random biopsies were able to detect some CIS not visible under PDD (AU)

Note: Equation of state and compressibility of supercooled water: simulations and experiment.

The equation of state and the isothermal compressibility of supercooled water for pressures up to 3000 bar obtained from computer simulations of the TIP4P/2005 model are compared to recent experimental results. The agreement between the simulations and experimental results is quite good. This reinforces the idea that the Widom line and the liquid-liquid phase separation found in the simulations should also exist in real water.

[Hexaminolevulinate photodynamic diagnosis in non-muscle invasive bladder cancer: experience of the BLUE group]. / Diagnóstico fotodinámico con hexaminolevulinato en el cáncer vesical no músculo invasivo: experiencia del grupo BLUE.

OBJECTIVES: Photodynamic diagnosis (PDD) with hexaminolevulinate has been recently used to improve detection of non-muscle invasive bladder cancer. Our main purpose was to quantify the benefit of PDD vs. conventional white light cystoscopy (WL) in our area. MATERIAL AND METHODS: Fluorescence-guided cystoscopy using hexaminolevulinate was performed at the time of the transurethral resection (TUR) in 305 patients from 7 Spanish hospitals. All lesions found with WL and PDD were numbered and recorded in an online database. Each lesion was sent separately for pathology analysis. Random biopsies were also obtained in 148 patients. RESULTS: A total of 1659 lesions were biopsied: 522 were identified with PDD and WL, 237 only with PDD, 19 only with WL and 881 random biopsies. Of the 600 tumors, PDD detected 563, WL 441 and random biopsies 29 (20 CIS). The mean overdetection rate for PDD over WL was 31.9% for all types of lesions, but it was 209% for carcinoma in situ (CIS). Sensitivity was 93.8% for PDD and 78.2% for WL. Specificity was 81.5% for PDD and 90.5% for WL. In 23% of patients, PDD detected at least one additional neoplastic lesion compared to WL. CONCLUSIONS: Hexaminolevulinate fluorescence cystoscopy improves detection and resection of non-muscle invasive bladder cancer, especially of CIS. Sensitivity of PDD is higher than WL, but specificity is lower. In our study, random biopsies were able to detect some CIS not visible under PDD.

Heat capacity of water: A signature of nuclear quantum effects.

In this note we present results for the heat capacity at constant pressure for the TIP4PQ/2005 model, as obtained from path-integral simulations. The model does a rather good job of describing both the heat capacity of ice I(h) and of liquid water. Classical simulations using the TIP4P/2005, TIP3P, TIP4P, TIP4P-Ew, simple point charge/extended, and TIP5P models are unable to reproduce the heat capacity of water. Given that classical simulations do not satisfy the third law of thermodynamics, one would expect such a failure at low temperatures. However, it seems that for water, nuclear quantum effects influence the heat capacities all the way up to room temperature. The failure of classical simulations to reproduce C(p) points to the necessity of incorporating nuclear quantum effects to describe this property accurately.

What ice can teach us about water interactions: a critical comparison of the performance of different water models.

The performance of several popular water models (TIP3P, TIP4P, TIP5P and TIP4P/2005) is analyzed. For that purpose the predictions for ten different properties of water are investigated, namely: 1. vapour-liquid equilibria (VLE) and critical temperature; 2. surface tension; 3. densities of the different solid structures of water (ices); 4. phase diagram; 5. melting-point properties; 6. maximum in the density of water at room pressure and thermal coefficients alpha and KT; 7. structure of liquid water and ice; 8. equation of state at high pressures; 9. self-diffusion coefficient; 10. dielectric constant. For each property, the performance of each model is analyzed in detail with a critical discussion of the possible reason of the success or failure of the model. A final judgement on the quality of these models is provided. TIP4P/2005 provides the best description of almost all properties of the list, the only exception being the dielectric constant. In second position, TIP5P and TIP4P yield a similar performance overall, and the last place with the poorest description of the water properties is provided by TIP3P. The ideas leading to the proposal and design of the TIP4P/2005 are also discussed in detail. TIP4P/2005 is probably close to the best description of water that can be achieved with a non-polarizable model described by a single Lennard-Jones (LJ) site and three charges.

Properties of ices at 0 K: a test of water models.

The properties of ices Ih, II, III, V, and VI at zero temperature and pressure are determined by computer simulation for several rigid water models (SPC/E, TIP5P, TIP4P/Ice, and TIP4P/2005). The energies of the different ices at zero temperature and pressure (relative to the ice II energy) are compared to the experimental results of Whalley [J. Chem. Phys. 81, 4087 (1984)]. TIP4P/Ice and TIP4P/2005 provide a qualitatively correct description of the relative energies of the ices at these conditions. In fact, only these two models provide the correct ordering in energies. For the SPC/E and TIP5P models, ice II is the most stable phase at zero temperature and pressure whereas for TIP4P/Ice and TIP4P/2005 ice Ih is the most stable polymorph. These results are in agreement with the relative stabilities found at higher temperatures. The solid-solid phase transitions at 0 K are determined. The predicted pressures are in good agreement with those obtained from free energy calculations.

Computer simulation of the ionic atmosphere around Z-DNA.

We describe a coarse-grained model for Z-DNA that mimics the DNA shape with a relatively small number of repulsive interaction sites. In addition, negative charges are placed at the phosphate positions. The ionic atmosphere around this grooved Z-DNA model is then investigated with Monte Carlo simulation. Cylindrically averaged concentration profiles as well as the spatial distribution of ions have been calculated. The results are compared to those for other DNA models differing in the repulsive core. This allows the examination of the effect of the DNA shape in the ionic distribution. It is seen that the penetrability of the ions to the DNA groove plays an important role in the ionic distribution. The results are also compared with those reported for B-DNA. In both conformers the ions are structured in alternating layers of positive and negative charge. In Z-DNA the layers are more or less concentric to the molecular axis. Besides, no coions enter into the single groove of this conformer. On the contrary, the alternating layers of B-DNA are also structured along the axial coordinate with some coions penetrating into the major groove. In both cases we have found five preferred locations of the counterions and two for the coions. The concentration of counterions reaches its absolute maximum at the narrow Z-DNA groove and at the minor groove of B-DNA, the value of the maximum being higher in the Z conformer.

Vapor-liquid equilibria from the triple point up to the critical point for the new generation of TIP4P-like models: TIP4P/Ew, TIP4P/2005, and TIP4P/ice.

The vapor-liquid equilibria of three recently proposed water models have been computed using Gibbs-Duhem simulations. These models are TIP4P/Ew, TIP4P/2005, and TIP4P/ice and can be considered as modified versions of the TIP4P model. By design TIP4P reproduces the vaporization enthalpy of water at room temperature, whereas TIP4P/Ew and TIP4P/2005 match the temperature of maximum density and TIP4P/ice the melting temperature of water. Recently, the melting point for each of these models has been computed, making it possible for the first time to compute the complete vapor-liquid equilibria curve from the triple point to the critical point. From the coexistence results at high temperature, it is possible to estimate the critical properties of these models. None of them is capable of reproducing accurately the critical pressure or the vapor pressures and densities. Additionally, in the cases of TIP4P and TIP4P/ice the critical temperatures are too low and too high, respectively, compared to the experimental value. However, models accounting for the density maximum of water, such as TIP4P/Ew and TIP4P/2005 provide a better estimate of the critical temperature. In particular, TIP4P/2005 provides a critical temperature just 7 K below the experimental result as well as an extraordinarily good description of the liquid densities from the triple point to the critical point. All TIP4P-like models present a ratio of the triple point temperature to the critical point temperature of about 0.39, compared with the experimental value of 0.42. As is the case for any effective potential neglecting many body forces, TIP4P/2005 fails in describing simultaneously the vapor and the liquid phases of water. However, it can be considered as one of the best effective potentials of water for describing condensed phases, both liquid and solid. In fact, it provides a completely coherent view of the phase diagram of water including fluid-solid, solid-solid, and vapor-liquid equilibria.

Correlation between the biopsies in marginal donor kidneys for transplantation: is it necessary to biopsy both kidneys?

OBJECTIVES: The objective of this study was to analyze the correlation between histological findings in both transplanted kidneys from marginal donors. METHODS: We retrospectively reviewed the histological information on 92 kidneys obtained between January 2001 and January 2004, corresponding to 46 marginal donors. Criteria for biopsy were age greater than 55 years, hypertension, diabetes, and proteinuria. Scores were established by the pathologist including glomerulosclerosis, tubular atrophy, interstitial fibrosis, and arteriosclerosis. The score for each lesion was classified as 0 if absent; 1 if <20%; 2 if >20% and <50%; and 3 if >50%. Finally, we defined an index of renal severity damage (RSD) in order to classify the kidneys for single transplantation (0), double transplantation (1), and unsuitable for transplantation (2). RESULTS: Of the kidneys studied, 82.6% of both kidneys showed similar degrees of glomerulosclerosis (<20% in 71.7% and >20% in 10.9%), while 17.4% showed discrepancies (> vs <20%; P=.008). On the other hand, RSD correlated in 82.6% of both kidneys (in 69.6% RSD=0; in 8.7% RSD=1; and in 4.3% RSD=2), while 17.4% showed discrepancies (P=.001). In one case (2.2%), a great discrepancy was observed; one kidney was valid for single transplantation, and the other one not valid for any transplantation, single or double. CONCLUSIONS: This study demonstrated a correlation between the biopsy findings in both kidneys in 82.6% of marginal organ donors. However, in 17.4% of cases we observed discrepancies. The degree of glomerulosclerosis seemed to be a powerful parameter to define renal severity damage. According to these results we would recommend biopsy of both kidneys.