Structure-preserving Gaussian denoising of FIB-SEM volumes.

FIB-SEM (Focused Ion Beam-Scanning Electron Microscopy) is an imaging technique that allows 3D ultrastructural analysis of cells and tissues at the nanoscale. The acquired FIB-SEM data are highly noisy, which makes denoising an essential step prior to volume interpretation. Gaussian filtering is a standard method in the field because it is fast and straightforward. However, it tends to blur the biological features due to its linear nature that ignores the rapid changes of the structures throughout the volume. To address this issue, we have developed a new approach to structure-preserving noise reduction for FIB-SEM. It has abilities to locally adapt the filtering to the biological structures while taking advantage of the simplicity of Gaussian filtering. It uses the Optical Flow (OF) to estimate the variations of the structural features across the volume, so that they are compensated before the subsequent filtering with a Gaussian function. As demonstrated qualitatively and objectively with datasets from different samples and acquired under different conditions, our denoising approach outperforms the standard Gaussian filtering and is competitive with state-of-the-art methods in terms of noise reduction and preservation of the sharpness of the structures.

Optical flow driven interpolation for isotropic FIB-SEM reconstructions.

BACKGROUND AND OBJECTIVE: Focused Ion Beam - Scanning Electron Microscopy (FIB-SEM) allows three-dimensional ultrastructural analysis of cells and tissues at the nanoscale. The technique iteratively removes a section of the sample with a FIB and takes an SEM image from the exposed surface. The section thickness is usually higher than the image pixel size to reduce acquisition time, thus resulting in anisotropic resolution. In this work, we explore novel interpolation methods along the sectioning direction to produce isotropic resolution and facilitate proper interpretation of the FIB-SEM 3D volumes. METHODS: Classical interpolation methods are usually applied in this context under the assumption that the changes through successive images are relatively smooth. However, the actual 3D arrangement of the structures in the sample may cause significant changes in the biological features between consecutive images of the FIB-SEM stacks. We have developed a novel interpolation strategy that accounts for this variation by using the Optical Flow (OF) to estimate it. As an intermediate stage, OF-compensated images are produced by aligning the spatial regions of the biological structures. Interpolated images are then generated from these OF-compensated images. The final isotropic stack is assembled by interleaving the interpolated images with the original images of the anisotropic stack. RESULTS: OF-driven and classical interpolation methods were compared using an objective assessment based on Pearson Correlation Coefficient (PCC) and a qualitative evaluation based on visual results, using public datasets and representative anisotropy conditions. The objective assessment demonstrated that the OF-driven interpolation always yields higher PCC values, with interpolated images closer to the ground truth. The qualitative evaluation corroborated those results and confirmed that classical interpolation may blur areas with substantial changes between consecutive images whereas OF-driven interpolation provides sharpness. CONCLUSIONS: We have developed an OF-driven interpolation approach to generating FIB-SEM stacks with isotropic resolution from experimental anisotropic data. It adapts to the rapid variation of the biological structures observed through the images of the FIB-SEM stack. Our approach outperforms classical interpolation and manages to produce sharp interpolated views in cases where there are significant changes between consecutive experimental images.

Incidencia de cardiopatía isquémica en el estudio HERMEX y su asociación con los factores de riesgo cardiovascular clásicos / Incidence of ischemic heart disease in the HERMEX study and its association with classical cardiovascular risk factors

Objetivos: El conocimiento sobre la incidencia de enfermedad coronaria en nuestro país es escaso y sus fuentes poco comparables. Fue nuestro objetivo determinar la incidencia de cardiopatía isquémica en una cohorte poblacional con un seguimiento de 7 años y el riesgo asociado a los factores de riesgo cardiovascular clásicos. Métodos: Estudio de cohortes prospectivo en una muestra poblacional de 2833 sujetos, seleccionada por método aleatorio simple entre ciudadanos de 25 a 79 años del Área de Salud Don Benito – Villanueva de la Serena (Badajoz), tasa de respuesta 80,5%. Se recogieron todos los episodios de angina de pecho, infarto de miocardio letal y no letal en individuos sin antecedentes previos de enfermedad cardiovascular. Se calcularon las incidencias acumuladas y las tasas de incidencia ajustadas por 100.000 personas-año por sexo y global. Resultados: De los 2833 participantes iniciales, se excluyeron 103 por antecedentes de enfermedad cardiovascular y 61 por pérdidas, completando el seguimiento 2669 (94,2%). La mediana de seguimiento fue de 6,9 años (RI 6,5 - 7,5), 56,4% mujeres; se registraron 59 eventos. La tasa de incidencia global de cardiopatía isquémica fue 327 casos/100.000 personas-año correspondiendo 470 casos/100.000 al sexo masculino y 211 casos/100.000 personas-año al femenino. Los factores de riesgo cardiovascular clásicos que se asociaron con mayor riesgo de presentar eventos en el seguimiento fueron la dislipemia y la HTA, además del sexo masculino y la edad. Conclusiones: La incidencia de cardiopatía isquémica en la población urbano-rural de Extremadura, es elevada. Los factores de riesgo cardiovascular clásicos más fuertemente asociados a su aparición fueron la dislipemia, y la hipertensión arterial (AU)

Objectives: Knowledge about the incidence of coronary heart disease in our country is scarce and its sources are not comparable. Our aim was to determine the incidence of ischemic heart disease in a population cohort in a 7 years of follow-up, as well as the risk associated with the different classical cardiovascular risk factors. Methods: Cohort study with a population sample of 2833 subjects, selected by the simple random method in a population between 25 and 79, from the Don Benito – Villanueva de la Serena (Badajoz) health area, response rate was 80.5%. All episodes of angina pectoris, lethal and non-lethal myocardial infarction were collected in individuals with no previous history of cardiovascular disease. Cumulative incidences and incidence rates adjusted per 100,000 person-years by sex and overall were calculated. Results: From 2833 initial cohort participants, 103 were excluded due to a history of cardiovascular disease and 61 for losses, 2669 completed the follow-up (94.2%). The median follow-up was 6.9 years (IR 6.5–7.5), 56.4% women; 59 events were recorded. The overall incidence rate of ischemic heart disease was 327 cases/100,000 person-years, corresponding to 470 cases/100,000 for men and 211 cases/100,000 people-years for women. The classical cardiovascular risk factors that were associated with a higher risk of presenting events in the follow-up were dyslipidemia and arterial hypertension, in addition to male sex and age. Conclusions: The incidence of ischemic heart disease in the urban–rural population of Extremadura is high. The classical cardiovascular risk factors most strongly associated with events were dyslipidemia, and arterial hypertension (AU)

[Incidence of ischemic heart disease in the HERMEX study and its association with classical cardiovascular risk factors]. / Incidencia de cardiopatía isquémica en el estudio HERMEX y su asociación con los factores de riesgo cardiovascular clásicos.

OBJECTIVES: Knowledge about the incidence of coronary heart disease in our country is scarce and its sources are not comparable. Our aim was to determine the incidence of ischemic heart disease in a population cohort in a 7 years of follow-up, as well as the risk associated with the different classical cardiovascular risk factors. METHODS: Cohort study with a population sample of 2833 subjects, selected by the simple random method in a population between 25 and 79, from the Don Benito - Villanueva de la Serena (Badajoz) health area, response rate was 80.5%. All episodes of angina pectoris, lethal and non-lethal myocardial infarction were collected in individuals with no previous history of cardiovascular disease. Cumulative incidences and incidence rates adjusted per 100,000 person-years by sex and overall were calculated. RESULTS: From 2833 initial cohort participants, 103 were excluded due to a history of cardiovascular disease and 61 for losses, 2669 completed the follow-up (94.2%). The median follow-up was 6.9 years (IR 6.5-7.5), 56.4% women; 59 events were recorded. The overall incidence rate of ischemic heart disease was 327 cases/100,000 person-years, corresponding to 470 cases/100,000 for men and 211 cases/100,000 people-years for women. The classical cardiovascular risk factors that were associated with a higher risk of presenting events in the follow-up were dyslipidemia and arterial hypertension, in addition to male sex and age. CONCLUSIONS: The incidence of ischemic heart disease in the urban-rural population of Extremadura is high. The classical cardiovascular risk factors most strongly associated with events were dyslipidemia, and arterial hypertension.

Numerical analysis of the pressure drop across highly-eccentric coronary stenoses: application to the calculation of the fractional flow reserve.

BACKGROUND: Fractional flow reverse (FFR) is the gold standard assessment of the hemodynamic significance of coronary stenoses. However, it requires the catheterization of the coronary artery to determine the pressure waveforms proximal and distal to the stenosis. On the contrary, computational fluid dynamics enables the calculation of the FFR value from relatively non-invasive computed tomography angiography (CTA). METHODS: We analyze the flow across idealized highly-eccentric coronary stenoses by solving the Navier-Stokes equations. We examine the influence of several aspects (approximations) of the simulation method on the calculation of the FFR value. We study the effects on the FFR value of errors made in the segmentation of clinical images. For this purpose, we compare the FFR value for the nominal geometry with that calculated for other shapes that slightly deviate from that geometry. This analysis is conducted for a range of stenosis severities and different inlet velocity and pressure waveforms. RESULTS AND CONCLUSIONS: The errors made in assuming a uniform velocity profile in front of the stenosis, as well as those due to the Newtonian and laminar approximations, are negligible for stenosis severities leading to FFR values around the threshold 0.8. The limited resolution of the stenosis geometry reconstruction is the major source of error when predicting the FFR value. Both systematic errors in the contour detection of just 1-pixel size in the CTA images and a low-quality representation of the stenosis surface (coarse faceted geometry) may yield wrong outcomes of the FFR assessment for an important set of eccentric stenoses. On the contrary, the spatial resolution of images acquired with optical coherence tomography may be sufficient to ensure accurate predictions for the FFR value.

Design and Testing of a New Diatom-Based Index for Heavy Metal Pollution.

The Tinto and Odiel river basins (SW Spain) are known worldwide for their unique water characteristics. Such uniqueness is a consequence of their flow through the Iberian Pyrite Belt (an area rich in metal sulphides) and the mining activities in the basins. A process of sulphide oxidation occurs in this region, which acidifies the water and increases the amount of heavy metals in it. As a result, the rivers suffer the so-called "acid mine drainage" (AMD). Traditional biotic diatom-based indexes (IPS, IBD, EPI-D, etc.) do not take into account the pollution caused by AMD. The purpose of this paper is to develop a new diatom-based index which can serve as a useful and quick monitoring tool. Such tool must reflect the level of AMD while being user friendly. We present the development and validation of the ICM (Índice de Contaminación por Metales or Metal Pollution Index). ICM demonstrated to meet successfully the above criteria and, therefore, can assess water quality in the Tinto and Odiel Rivers. In addition, ICM was applied with satisfactory results in the Guadiamar River (SW Spain), which was subjected to AMD too. Thus, we propose to make use of it in any other basin with the same type of pollution.

Influence of different photo-activation distances on cytotoxicity of a dental adhesive model resin.

AIM: This study evaluated the cytotoxicity of a dental bonding model resin (DBMR) submitted to different photo-activation distances. METHODS: A monomer mixture based on Bis-GMA and HEMA was used to assess the cytotoxicity in a mouse fibroblast-cell line. To promote different photo-activation distances glass slides were interposed between DBMR surface and halogen light curing unit (LCU) tip. Afterwards, the specimens were immersed in RPMI culture medium for 24 h to obtain extracts. The extracts were incubated in contact with the cells for 24 h. Finally, an MTT colorimetric assay was used to assess the cytotoxicity. The cell viability data (absorbance) were analyzed by one way ANOVA followed by Tukey's test (P<0.05). RESULTS: The light output decreased according to the increase in the number of glass slides between the halogen LCU tip and DBMR surface. Yet, the distance between the tip of the curing light system and the specimens had significant influence on the cytotoxicity. All extracts produced by groups submitted to different photo-activation distances showed cytotoxic effect after 24h of incubation. CONCLUSION: The photo-activation distance and the interposition of glass slides between LCU tip and DBMR was shown to play an important role in the cytotoxic effect.

[Anti-NMDA receptor encephalitis in a 3-year-old girl with no associated pathology involving a tumour]. / Encefalitis antirreceptor de NMDA en una nina de 3 anos sin patologia tumoral asociada.

INTRODUCTION: Encephalitis due to NMDA receptors antibodies is a relatively common condition but it was under diagnosed until recently. It courses predictably and similarly in adults and children, although there are some differences, still less its association with tumours. CASE REPORT: A 3 years-old girl who was admitted to our hospital with symptoms compatible with acute encephalitis, so we started treatment with acyclovir. During admission she was alterning periods of poor response to stimuli with periods of agitation, and progressed to complete silence, adding sleep problems. She suffered epileptic seizures, dystonic movements and autonomic disturbances. Cranial MRI showed mild cortical atrophy and EEG generalized slowing of base tracing. Repeated samples of cerebral spinal fluid were normal from cytological and biochemical point of view. In view of the torpid evolution she began methylprednisolone therapy and later inmunoglobulins with no improvement. Upon confirmation of the positivity for NMDA receptors antibodies in cerebral spinal fluid and serum, cyclophosphamide was administered, with gradual improvement of symptoms until full recovery. After ten months of follow-up without treatment she has not presented relapses and has ruled out the presence of tumours. CONCLUSIONS. It is important to recognize encephalitis with behavioural changes and abnormal movements, because early diagnosis and the beginning of appropriate therapy could improve the prognosis.

PDMS-based porous particles as support beds for cell immobilization: bacterial biofilm formation as a function of porosity and polymer composition.

The objective of this work is to test the performance of new synthetic polydimethylsiloxane (PDMS)-based bed particles acting as carriers for bacteria biofilms. The particles obtained have a highly interconnected porous structure which offers a large surface adsorption area to the bacteria. In addition, PDMS materials can be cross-linked by copolymerization with other polymers. In the present work we have chosen two hydrophilic polymers: xanthan gum polysaccharide and tetraethoxysilane (TEOS). This versatile composition helps to modulate the interfacial hydrophobic/hydrophilic balance at the particle surface level and the roughness topology and pore size distribution, as revealed by scanning electron microscopy. Biofilm formation of a consortium isolated from a tannery effluent enriched in Sulphate Reducing Bacteria (SRB), and pure Acidithiobacillus ferrooxidans (AF) strains were assayed in three different bed particles synthesized with pure PDMS, PDMS-xanthan gum and PDMS-TEOS hybrids. Bacterial viability assays using confocal laser scanning fluorescence microscopy indicate that inclusion of hydrophilic groups on particle's surface significantly improves both cell adhesion and viability.

Cytotoxicity and genotoxicity of sodium percarbonate: a comparison with bleaching agents commonly used in discoloured pulpless teeth.

AIM: To evaluate the cytotoxicity and genotoxicity of sodium percarbonate (SPC) in comparison with bleaching agents used on discoloured pulpless teeth. METHODOLOGY: The cytotoxicity and genotoxicity of bleaching agents were evaluated both in their pure form as well as at concentrations commonly used in clinical practice. Hydrogen peroxide (HP), carbamide peroxide (CP), sodium perborate (SP) and SPC were diluted in Dulbecco's modified Eagle's medium (DMEM) in series. To evaluate the cytotoxicity, the survival of 3T3/NIH mouse fibroblasts was measured photometrically using an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay after a 24 h-exposure period. Genotoxicity was indicated by micronuclei (MN) formation, and modification of the normal cell was analysed by light microscopy (400x). Statistical analysis was performed by one-way anova, followed by a multiple-comparison Tukey post hoc test (P < 0.05). RESULTS: All groups exhibited a dose-dependent cytotoxicity. However, CP showed a similar cytotoxic effect when compared with DMEM-untreated control (UC) group. HP and SPC were significantly more cytotoxic than SP. The genotoxicity test showed that SPC and SP had an intermediate rate of MN frequency when compared with the UC group. The mean rate of MN frequency for HP was higher and statistically more significant than for the other groups tested. No difference was observed when CP and UC groups were compared. CONCLUSIONS: Sodium percarbonate showed cytotoxicity and genotoxicity similar to those of the other products tested. However, before SPC is used clinically, studies should be conducted to confirm its safety in vivo.

Mortality in patients with dementia treated with atypical antipsychotics (olanzapine, quetiapine and ziprasidone).

INTRODUCTION: The atypical antipsychotics (AA) quetiapine, olanzapine and ziprasidone are used to treat behavioural disorders associated with dementia. This indication does not appear on their technical sheet. The object of this study is to analyse the relationship of these treatments with mortality and other factors. METHOD: Retrospective study from March 2005 to July 2007 of AA treatments requested as compassionate use. We collected information on mortality, age, history of heart disease or cerebrovascular disease, and duration and number of concomitant treatments per patient. RESULTS: 289 patients were studied. Mortality was 31.1%. A higher mortality rate was shown for patients with a history of heart disease and in those who used olanzapine. Quetiapine was the most commonly prescribed antipsychotic drug. CONCLUSIONS: The use of AA in the elderly could have risks that outweigh the benefits. When prescribing these drugs for at-risk patients, one should consider their safety warnings and the individual case of each patient. According to our data, olanzapine seems to be associated with a higher risk than quetiapine and ziprasidone.

Whole-cell protein and ITS rDNA profiles as diagnostic tools to discriminate Fusarium avenaceum intraspecific variability and associated virulence.

A total of 91 isolates of Fusarium avenaceum were regrouped into 15 phenotypes and 10 vegetative compatibility groups showing specific one-dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis (1-D SDS-PAGE) protein profiles and less-specific internal transcribed spacer rDNA profiles. Each isolate possessed reproducible signature protein bands. Indeed, the unweighted pair group method with arithmetic averages clustering revealed that the protein profile of each group of isolates correlated with fungus virulence. The use of SDS-PAGE offers a simple and sensitive technique for routine differentiation between pathogenic and nonpathogenic isolates within unknown F. avenaceum populations. The discovery has significant implications for risk assessment of cereal yield to ensure food and feed safety. This low-cost approach has the potential to be optimized and extended to a broad spectrum of Fusarium head blight pathogens.

Development and characterization of an active polyethylene film containing Lactobacillus curvatus CRL705 bacteriocins.

The development and characterization of a bacteriocin-containing polyethylene-based film is described, incorporating lactocin 705 and lactocin AL705, produced by Lactobacillus curvatus CRL705, and nisin. Three different procedures to obtain lactocin 705 and AL705 solution were evaluated, with the partially purified aqueous bacteriocin solution showing the highest inhibitory activity against indicator strains (Lactobacillus plantarum CRL691 and Listeria innocua 7). Pouch contact, soaking and a contact method were compared for incorporating bacteriocins onto PE-based films. Contact between the PE film and bacteriocin solution was the most effective, resulting in a more uniform distribution of bacteriocins on the film surface and using less active solution. The minimal inhibitory concentration of bacteriocin solution was 267 AU cm(-3) (lactocin 705) and 2133 AU cm(-3) (lactocin AL705), while the minimal contact time was 1 h. When relative inhibition area for antilisterial activity of the active films was compared, those treated with L. curvatus CRL705 bacteriocins displayed higher inhibitory activity than nisin-treated films. Functional properties of active PE-films containing lactocin 705 and AL705 showed no differences compared with non-active control films. Bacteriocin-active PE-based films are shown to be highly effective in inhibiting growth of Listeria. The potential use of commercially available packaging films as bacteriocins carriers may benefit active-packaging systems.

Human and yeast zeta-crystallins bind AU-rich elements in RNA.

Zeta-crystallins constitute a family of proteins with NADPH:quinone reductase activity found initially in mammalian lenses but now known to be present in many other organisms and tissues. Few proteins from this family have been characterized, and their function remains unclear. In the present work, zeta-crystallins from human and yeast (Zta1p) were expressed, purified and characterized. Both enzymes are able to reduce ortho-quinones in the presence of NADPH but are not active with 2-alkenals. Deletion of the ZTA1 gene makes yeast more sensitive to menadione and hydrogen peroxide, suggesting a role in the oxidative stress response. The human and yeast enzymes specifically bind to adenine-uracil rich elements (ARE) in RNA, indicating that both enzymes are ARE-binding proteins and that this property has been conserved in zeta-crystallins throughout evolution. This supports a role for zeta-crystallins as trans-acting factors that could regulate the turnover of certain mRNAs.