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.

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.

[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.

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.

[pulmonary thromboembolism in hospitalized patients during the period 1994-2000: an autopsy study]. / Tromboembolismo pulmonar en pacientes hospitalizados entre 1994-2000: serie de autopsia.

BACKGROUND: Pulmonary thromboembolism (PTE) has been for a long time a significant cause of morbidity and mortality in hospitalized patients. The utility of Low-Molecular Weight Heparins (LMWH) in these patients in the last decade of the XX century has decreased the incidence of this disease. We try to know if the massive useful of LMWH as thromboprophylasis is diminishing its incidence in autopsies. MATERIAL AND METHODS: Retrospective study of all the autopsies in adults in the Hospital Clínico San Carlos (Madrid) in a period of 6 years (from January 1994 to December 1999). There were reviewed those necropsies which had pathological data of pulmonary thromboembolism and several items were studied: anatomopathological, epidemiological, clinical and therapeutical. RESULTS: 483 necropsies were performed in this period; 40 (8.3%) had PE. Most of them were older than 50 years (85%) and the most important risk factors associated were bedridden, chronic cardiovascular diseases and malignant neoplasias. Only Pre-mortem diagnosis was only suspected in 5 patients (12.5%) and 15 of them (37.5%) had a fatal pulmonary embolism despite receipt of thromboprophylasis with LMWH. CONCLUSIONS: PTE is still an important cause of mortality in hospitalized patients. The increased of life expect, survival of chronic cardiovascular and malignant disease made PTE a frequent possibility situation in hospitalized patients. Receipt of LMWH as thromboprophylaxis is not always effective to avoid PTE.

Pathogenicity of Fusarium Species on Different Plant Parts of Spring Wheat Under Controlled Conditions.

Most of the Fusarium species responsible for Fusarium head blight of wheat in Saskatchewan, Canada, have also been isolated from discolored subcrown internodes/crowns of wheat. It was therefore of interest to compare the susceptibility of heads and ground/underground tissue of wheat to isolates of Fusarium species from different sources. Controlled-environment pathogenicity tests were conducted on heads, seeds, and seedlings of spring wheat. Overall, F. culmorum and F. graminearum were the most pathogenic species, although the former was more pathogenic than the latter. F. equiseti and F. poae were the least pathogenic species, whereas F. avenaceum had intermediate pathogenicity in the head and seed tests, but low pathogenicity in the seedling test. There was a similar pathogenicity among isolates of each Fusarium species from different sources to heads and ground/underground plant parts, indicating a lack of adaptation of these isolates. Our observations suggest that Fusarium inoculum on or in infected seed or plant debris might infect plants at or below soil level, which could then become a source of inoculum for infection of heads in the following season(s). Survival of fungal inoculum in underground plant parts might be important during dry conditions.

Effects of thromboxane synthesis inhibitor triflusal on renal hemodynamics in microalbuminuric diabetic patients.

Triflusal (2-acetoxy-4-trifluormethylbenzoic acid) is a platelet-antiaggregant drug that selectively inhibits thromboxane synthesis with little effect on prostacyclin production. In this study, we evaluated the effect of 5-day administration of 900 mg/day triflusal on glomerular filtration rate (GFR), renal plasma flow (RPF), urinary albumin excretion (UAE), thromboxane B2 (TXB2), 6-ketoprostaglandin F1 alpha (PGF1 alpha), and PGE2 in nine normotensive insulin-dependent diabetic patients with UAE between 30 and 103 micrograms/min. Plasma TXB2 and plasma renin activity (PRA) were also determined. After administration of triflusal, we observed a reduction in microalbuminuria (59 +/- 25 vs. 33 +/- 22 micrograms/min, P less than 0.01), an increase in RPF (648 +/- 119 vs. 722 +/- 134 ml.min-1 x 1.73 m-2, P less than 0.01), and a reduction in filtration fraction (0.24 +/- 0.04 vs. 0.20 +/- 0.03, P less than 0.01). Triflusal produced a significant reduction in both plasma TXB2 (130 +/- 39 vs. 52 +/- 32 pg/ml, P less than 0.02) and urine TXB2 (523 +/- 249 vs. 312 +/- 11 pg/min, P less than 0.02), without changes in PRA and UAE of 6-keto-PGF1 alpha and PGE2. Metabolic control and arterial blood pressure did not change during the study. These results suggest that platelet-antiaggregant therapy can reduce microalbuminuria in diabetic patients. This effect could be mediated by a reduction in the transglomerular hydraulic pressure through a vasodilation of efferent arterioles secondary to renal thromboxane synthesis inhibition.

[Mycotic aneurism in aortic arch by Aspergillus fumigatus: contribution of a case and review of the literature]. / Aneurisma micótico en cayado aórtico por Aspergillus fumigatus: aportación de un caso y revisión en la literatura.

The micotic aneurisms by Aspergillus are rare and usually appear in the context of an invasive pulmonary aspergilosis, or by septicum embolism or direct extension from the lungs, for that reason the location the more frequents is in aortic arch and the ascending aorta.8 cases of micotic aneurisms by Aspergillus spp. have been described in literature between 1966 and 2000, being the most frequent location the ascending aorta or the aortic arch. The Aspergillus fumigatus is the isolated species with more frequency, affecting mainly to patients undergoing inmunosupression. The diagnosis of a micotic aneurism requires a high clinical suspicion, given to its peculiarity and the presence of inespecific symptoms, being frequently an accidental finding in an invasive pulmonary aspergilosis.The case of a patient with a micotic aneurism by A. fumigatus appears and we reviewed the similar cases previously disclosed.

Renal hemodynamic abnormalities in patients with short term insulin-dependent diabetes mellitus: role of renal prostaglandins.

To determine if renal functional alterations in diabetes mellitus could be related to disturbances of vasoactive systems, renal plasma flow (RPF), glomerular filtration rate (GFR), PRA (basal and stimulated), plasma catecholamine levels, and urinary excretion of prostaglandin E2 (PGE2), 6-keto-PGF1 alpha, and kallikrein were determined in 21 patients with insulin-dependent diabetes mellitus (IDDM) of short duration and 15 normal subjects. In 7 additional patients with IDDM and in 4 normal subjects, the effect of lysine acetylsalicylate (LAS; 450 mg, iv) on GFR and RPF was studied. Patients with IDDM had higher RPF and GFR than normal subjects. Plasma norepinephrine and basal and stimulated PRA were significantly lower in IDDM than in the control group [161 +/- 82 (+/- SD) vs. 243 +/- 114 pg/ml, 0.19 +/- 0.20 vs. 1.15 +/- 0.33 ng/ml X h, and 0.93 +/- 0.82 vs. 2.8 +/- 1.73 ng/ml X h, respectively). No significant differences were found in the urinary excretion of PGE2, 6-keto-PGF1 alpha, and kallikrein in the two groups. LAS administration significantly reduced RPF (from 641 +/- 72 to 535 +/- 38 ml/min X 1.73 m2) and GFR (from 168 +/- 25 to 150 +/- 18 ml/min X 1.73 m2) in patients with IDDM, but not in normal subjects. In IDDM patients, there was a close direct correlation between the percent decrease in RPF and GFR induced by LAS and the baseline values of these parameters. The results suggest that in IDDM, there may be an imbalance between the degree of activation of the renin-angiotensin and sympathetic nervous systems and the renal production of PGs. The observation that LAS administration reduced RPF and GFR in these patients suggests that renal PGs are involved in the renal hyperperfusion of IDDM.

Structure of the gene encoding anchorin CII (chick annexin V).

Anchorin CII (annexin V) was first characterized as a collagen-binding protein and later identified as the chick homologue of human endonexin II, a member of the annexin gene family. Its gene (anx5) structure and sequence have been investigated to provide insight into the evolution and regulation of this important protein, and to elucidate its putative role in signal transduction and cellular differentiation. Four chick genomic clones encoding anchorin CII were isolated and characterized by restriction analysis, Southern blotting and sequencing. The anchorin CII-encoding gene spans about 24 kb and consists of 13 exons ranging in length from 50 to 561 bp, interrupted by 12 introns of 94 bp to 7 kb. Its promoter sequence contained no TATA box, but did display a high G+C content and multiple Sp1-binding sites typical of 'housekeeping' genes. Potential binding sites for transcription factors in the 5'-upstream region are consistent with regulation of anx5 expression by mitogens, oncoproteins, steroids and possibly metals. Genomic Southern blotting confirmed that chick anx5 is present as a single-copy gene.

The gene encoding human annexin V has a TATA-less promoter with a high G+C content.

Annexin V is a phospholipase A2 and protein kinase C inhibitory protein with calcium channel activity and an undefined role in cellular signal transduction, inflammation, growth and differentiation. Three genomic clones for human annexin V (ANX5) were characterized by restriction analysis, Southern blotting and sequencing. ANX5 spans at least 29 kb of the human genome and contains 13 exons ranging in length from 44 to 513 bp and 12 introns from 232 bp to 8 kb. The absence of a typical TATA box and the presence of high G+C content and Sp1-binding sites in its promoter characterize it as a 'housekeeping' gene and account for its broad pattern of expression. Potential binding sites for cis-regulatory elements identified in the 5'-upstream region of annexin V are consistent with its known regulation by oncogenic and growth-related stimuli. ANX5, like its chick homologue, differs from the genes encoding annexins I, II and III in features of its promoter and in the size of its exons 1, 2 and 3 in ways that may impart individuality to its regulation and function.

Class III alcohol dehydrogenase from Saccharomyces cerevisiae: structural and enzymatic features differ toward the human/mammalian forms in a manner consistent with functional needs in formaldehyde detoxication.

Alcohol dehydrogenase class III (glutathione-dependent formaldehyde dehydrogenase) from Saccharomyces cerevisiae was purified and analyzed structurally and enzymatically. The corresponding gene was also analyzed after cloning from a yeast genome library by screening with a probe prepared through PCR amplification. As with class III alcohol dehydrogenase from other sources, the yeast protein was obtained in two active forms, deduced to reflect different adducts/modifications. Protein analysis established N-terminal and C-terminal positions, showing different and specific patterns in protein start positions between the human/mammalian, yeast, and prokaryotic forms. Km values with formaldehyde differ consistently, being about 10-fold higher in the yeast than the human/mammalian enzymes, but compensated for by similar changes in kcat values. This is compatible with the different functional needs, emphasizing low formaldehyde concentration in the animal cells but efficient formaldehyde elimination in the microorganisms. This supports a general role of the enzyme in formaldehyde detoxication rather than in long-chain alcohol turnover.

Development of an antigen presentation system based on plum pox potyvirus.

The development of an antigen presentation system based on the plum pox potyvirus (PPV) is here described. The amino-terminal part of PPV capsid protein was chosen as the site for expression of foreign antigenic peptides. Modifications in this site were engineered to avoid the capability of natural transmission by aphids of this PPV vector. As a first practical attempt, different forms of an antigenic peptide (single and tandem repetition) from the VP2 capsid protein of canine parvovirus (CPV) were expressed. Both chimeras are able to infect Nicotiana clevelandii plants with similar characteristics to wild-type virus and remain genetically stable after several plant passages. The antigenicity of purified chimeric virions was demonstrated, proving the suitability of this system for diagnostic purposes. Moreover, mice and rabbits immunized with chimeric virions developed CPV-specific antibodies, which showed neutralizing activity.