Characterization of the Electrophysiological Characteristics of Chronic Atrial Fibrillation for Efficient Simulations

Atrial biophysical simulations have the potential to enhance outcomes by enabling the simulation of pharmacological and ablative strategies. However, the high computational times associated with such simulations render them unsuitable for diagnostic purposes. To address this challenge, discrete models such as cellular automata (CA) have been developed, which consider a finite number of states, thus significantly reducing computational times. Yet, there is a pressing need to determine whether CA can replicate pathological simulations with accuracy. The analysis of simulations under different degrees of electrical remodeling shows an expected increase of Action Potential Duration (APD) with the previous Diastolic Interval (DI) interval, indicating short-term memory of atrial cardiomyocytes: shorter APD0 provoked shorter APD+1, and previous DI has a similar effect on APD+1. Independent prediction using both APD0 and DI was found to provide a far better estimation of APD+1 values, compared to relying on DI alone (p<<0.01). Finally, the CA models were able to replicate reentrant patterns and cycle lengths of different states of atrial remodeling with a high degree of accuracy when compared to biophysical simulations. Overall, the use of atrial CA with short-term memory allows accurate reproduction of arrhythmic behavior in pathological tissue within a clinically relevant timeframe.Clinical Relevance- Discrete electrophysiological models simulate pathological self-sustained arrhythmias in diagnostic times.

Assessment of Risk for Ventricular Tachycardia based on Extensive Electrophysiology Simulations

Patients that have suffered a myocardial infarction are at high risk of developing ventricular tachycardia. Patient stratification is often determined by characterization of the underlying myocardial substrate by cardiac imaging methods. In this study, we show that computer modeling of cardiac electrophysiology based on personalized fast 3D simulations can help to assess patient risk to arrhythmia. We perform a large simulation study on 21 patient digital twins and reproduce successfully the clinical outcomes. In addition, we provide the sites which are prone to sustain ventricular tachycardias, i.e, onset sites around the scar region, and validate if they colocalize with exit sites from slow conduction channels.Clinical relevance- Fast electrophysiological simulations can provide advanced patient stratification indices and predict arrhythmic susceptibility to suffer from ventricular tachycardia in patients that have suffered a myocardial infarction.

OSNA Total Tumor Load for the Prediction of Axillary Involvement in Breast Cancer Patients: Should We use Different Thresholds According to the Intrinsic Molecular Subtype? MOTTO Study

Aims

To assess the impact of the molecular subtype (MS) on the total number of CK19 mRNA copies in all positive SLN (TTL) threshold, to predict non-SLN affectation, and to compare 5 years progression-free survival (PFS) according to the risk of recurrence (ROR) group by PAM50.

Methods

Cohort with infiltrating breast cancer with intra-operative metastatic SLN detected by one-step nucleic acid amplification (OSNA) assay who underwent subsequent ALND. Logistic regression was used to assess a possible interaction between TTL and MS(Triple Negative, Her-2-Enriched, Luminal A, or Luminal B), or hormone receptors (HR: positive or negative) by immunohistochemistry (IMH). Cox regression was used to compare PFS and OS in the 3 ROR groups (high, medium, or low).

Results

TTL was predictive of non-SLN affectation in both univariate (OR [95% CI]: 1.72 [1.43, 2.05], P < .001) and multivariate (1.55 [95% CI: 1.04, 2.32], P = .030) models, but MS-IMH or HR-IMH, and their interactions with TTL were not (best multivariate model: HR + main effect OR 1.16 [95% CI: 0.18, 7.64], P = .874; interaction OR: 1.04 [0.7, 1.55], P = .835; univariate model: HR + main effect OR: 1.44 [95% CI: 0.85, 2.44], P = .180). PFS was lower in the high-risk ROR group (81.1%) than in the low-risk group (93.9%) (HR: 3.68 [95 CI: 1.70, 7.94], P < .001).

Conclusions

our results do not provide evidence to support the utilization of subtype-specific thresholds for TTL values to make therapeutic decisions on the axilla. The ROR group was predictive of 5 years-PFS.

P-108 MARJOLIN'S ULCER AS A COMPLICATION OF UNRESOLVED OPEN ABDOMEN

Introduction

Marjolin's ulcer (MU) is a rare cutaneous tumour, commonly associated with chronic wounds with difficult healing.

We present a case of UM diagnosed on a persistent unresolved open abdominal closure wound.

Materials and Methods

80-year-old male with a history of ruptured infrarenal aortic aneurysm (2010) that required aorto-unifemoral repair. Postoperative period requiring decompressive laparotomy for abdominal compartment syndrome and treated with negative pressure therapy, and impossibility of definitive abdominal closure due to abdominal muscle retraction.

Loss of outpatient follow-up for 10 years.

Consultation for worsening of the surgical wound with abdominal pain. Examination revealed abdominal incisional hernia M2–4W3 and large abdominal ulcer. Biopsies positive results for squamous cell carcinoma with infiltrative pattern. A computed tomography describes an abdominal wall mass of 14×6×11cm and space-occupying lesion in the left hepatic lobe. Liver biopsy showed a moderately differentiated hepatocarcinoma.

Surgical management consist in intramuscular injection of botulinum toxin and en bloc resection of granulation and ulcerated tissue and ileal loop attached to the lesion. Wall reconstruction with anterior separation of components and supraponeurotic mesh.

Conclusions

Marjolin's ulcer is associated with squamous cell carcinoma with a high rate of metastasis and mortality. This tumour is considered infrequent, of long-term duration and associated with developing societies.

In our environment, this neoplasia can develop in patients with open abdomen treated partially or with closure by second intention, so we consider it necessary to have a high index of diagnostic suspicion in these cases and to perform biopsies for its detection.

Spatiotemporal signatures of response to atrial fibrillation ablation

Background

Atrial fibrillation (AF) can have organized regions, in the form of consistent dominant frequency sites, focal or reentrant sites, but it is unclear how these overlap with or differ from focal atrial tachycardias (AT) or potential drivers. We set out to develop an intuitive method based on fundamental electrogram shape and timing to separate types of AF.

Objective

To test the hypothesis that spatial regions of electrogram (EGM) in AF that show similar shapes over time based on cross-correlation analysis may separate patients with differing response to ablation.

Methods

We recruited N=133 patients (63.8±12.1 Y, 32% women), (i) N=10 had AT, (ii) N=122 AF that was or was not terminated by ablation, and (iii) N=1 pacing. All patients had left atrial mapping by 64 pole baskets. We applied repetitive activity (REACT) mapping that correlates EGMs in contiguous 2x2 regions (Fig. 1A) over 4sec. To calibrate REACT, we introduced simulated variations in shape (gaussian noise) and timing (gaussian delay) to pacing EGMs and computed nomograph over 100 random trials (Fig. 1C).

Results

Fig. 1B shows that REACT in a 71-year-old man with AT is more organized than in a 65 YO man with AF (100% vs 40% mapped field). Overall, REACT was higher in AT than AF (0.63±0.15 vs 0.36±0.22, p&lt;0.001). There were 24 cases in which global REACT between AF and AT groups had the overlapping range of values, indicating organized “islands” in AF analogous to AT. From nomograph in Fig. 1C we identified that this overlap reflects 15 ms variation in cycle length and 20% variation in EGM shape (labelled “x” in Fig. 1C).

Conclusion

Basic electrogram properties in AF of similar shapes in spatial areas over time can separate response to ablation and may represent “islands” of AT. Future studies should investigate the mechanisms for such islands and whether they may be targeted for therapy.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): US National Institutes of Health

Automatic left atrial segmentation from cardiac CT using computer graphics imaging and deep learning

Introduction

Segmenting left atrial (LA) substructures, including the LA body, appendage (LAA), and pulmonary veins (PVs), from computed tomography (CT) is central to electroanatomic mapping for ablation and functional studies in patients with atrial fibrillation (AF). However, this process requires manual outlining which needs special training, is subjective, and is difficult to scale. Computer graphics imaging (CGI) has been applied in media, film, and computer-aided design to reliably segment complex structures using their basic geometric representations.

Purpose

We hypothesized that LA substructures can be “virtually” dissected using CGI to separate geometric contours of the “convex ellipsoid” LA, “tubular” PVs, and “conical” LAA. We further hypothesized that the results of virtual dissection can be used to train a deep learning (DL) model to segment raw CT scans.

Methods

First, a mathematical method based on CGI techniques – erosion and dilation – was developed to “virtually dissect” the convex LA body from the original concave shell in publicly available digital atria with diverse simulated morphologies (Fig. 1A). The PVs and LAA were then automatically revealed and labeled by a 3D subtraction approach. Second, we refined precise LA/PV/LAA boundaries by tuning hyper-parameters from N=5 patient shells (Fig. 1B). Third, we used virtual dissection to train a DL model to segment CTs in N=20 patient atria (Fig. 1C). Finally, we applied this pipeline to segment raw CTs in a validation cohort of N=105 patients (23.8% women, 63.8±10.3Y; Fig. 1D).

Results

Virtual dissection accurately identified LA/PV/LAA boundaries in the training set (Dice coefficients 89–98%). In the independent test cohort (N=105), this automated pipeline accurately segmented raw CTs with Dice 81–95% (Fig. 1D) compared to a panel of experts (p&lt;0.001).

Conclusion

CGI of basic cardiac geometry combined with deep learning in small datasets can accurately segment raw CT scans in large populations. This computational pipeline may automate and simplify cardiac image processing and ablation procedures, and could be applied to the ventricle or other organ systems for diverse therapeutic strategies or to train machine learning.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Institutes of Health

Abstract 1974: C3G down-regulation in glioblastoma induces a pro-invasive and glycolytic phenotype, accompanied by RTKs dysregulation

C3G is a guanine-nucleotide exchange factor (GEF) for Rap1, although it can act through GEF-independent mechanisms. C3G plays a dual role in cancer, acting as either a tumor suppressor or inducer depending on the tumor type/stage. It regulates different key aspects of the tumorigenic process such as invasion, apoptosis or proliferation. In colon carcinoma, C3G represses invasion through down-regulation of p38αMAPK activity and promotes tumor growth. We have now analyzed the role of C3G in glioblastoma (GBM), a tumor characterized by its aggressiveness and disseminative capacity. To do it, we have used different experimental approaches: permanent gene silencing, knock-out using CRISPR/Cas9 technology and transient overexpression in U87 cell line and patient-derived GBM cells. We found that C3G down-regulation enhances invasion through the induction of an epithelial/glial to mesenchymal transition-like process. C3G deficiency also facilitates foci generation in anchorage-dependent and independent growth assays, but with lower cell density as a consequence of a reduced proliferation. In in vivo analyses, cells with C3G knock-down generated larger tumors in xenografts and chick chorioallantoic membrane xenografts assays with increased angiogenesis and α-SMA+ fibroblasts, but a lower proliferation. Mechanistically, C3G down-regulation impairs EGF/EGFR signaling by decreasing EGFR cell membrane localization, leading to a reduction in EGF/EGFR-induced invasiveness. In contrast, C3G down-regulation promotes the activation of several receptor tyrosine kinases (RTKs) that might promote invasion. In particular, the enhanced FGF2/FGFR1 signaling increases invasion in C3G-silenced cells, through a mechanism likely dependent on ERKs. Moreover, a proteomic analysis revealed that C3G down-regulation increases the levels of different key glycolytic enzymes, such as aldolase, phosphoglycerate kinase, enolase and pyruvate kinase (PK). The activity of PK and lactate dehydrogenase as well as lactate release to the extracellular environment were also increased upon C3G silencing. In conclusion, our data demonstrate that C3G inhibits invasion of GBM cells, while increasing their proliferative capacity. Moreover, we show a distinct dependency on C3G for EGF/EGFR signaling versus other RTKs, suggesting that assessing C3G levels may discriminate GBM patient responders to different RTK inhibitors. In addition, our results indicate that C3G regulates not only GBM growth and invasiveness, but it also contributes to reprogram its glycolytic metabolism. Hence, low levels of C3G correlate with a more mesenchymal and glycolytic phenotype with enhanced aggressiveness and worse patient prognosis. This promising role of C3G as a key player in GBM should be further characterized to define its prognostic value and its potential relevance as a predictor of the response to therapy.

Citation Format: Sara Manzano, Óscar Herranz, Paloma Bragado, Patricia Jáuregui, María Rodrigo, Celia Sequera, Cristina Baquero, Nerea Palao, Ignacio Rubio, Álvaro Gutierrez-Uzquiza, Carmen Guerrero, Almudena Porras. C3G down-regulation in glioblastoma induces a pro-invasive and glycolytic phenotype, accompanied by RTKs dysregulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1974.

A robust wavelet-based approach for dominant frequency analysis of atrial fibrillation in body surface signals

OBJECTIVE

Atrial dominant frequency (DF) maps undergoing atrial fibrillation (AF) presented good spatial correlation with those obtained with the non-invasive body surface potential mapping (BSPM). In this study, a robust BSPM-DF calculation method based on wavelet analysis is proposed.

APPROACH

Continuous wavelet transform along 40 scales in the pseudo-frequency range of 3-30 Hz is performed in each BSPM signal using a Gaussian mother wavelet. DFs are estimated from the intervals between the peaks, representing the activation times, in the maximum energy scale. The results are compared with the traditionally widely applied Welch periodogram and the robustness was tested on different protocols: increasing levels of white Gaussian noise, artificial DF harmonics presence and reduction in the number of leads. A total of 11 AF simulations and 12 AF patients are considered in the analysis. For each patient, intracardiac electrograms were acquired in 15 locations from both atria. The accuracy of both methods was assessed by calculating the absolute errors of the highest DF _BSPM (HDF _BSPM ) with respect to the atrial HDF, either simulated or intracardially measured, and assumed correct if ≤1 Hz. The spatial distribution of the errors between torso DFs and atrial HDFs were compared with atria driving mechanism locations. Torso HDF regions, defined as portions of the maps with [Formula: see text] Hz were identified and the percentage of the torso occuping these regions was compared between methods. The robustness of both methods to white Gaussian noise, ventricular influence and harmonics, and to lower spatial resolution BSPM lead layouts was analyzed: computer AF models (567 leads vs 256 leads down to 16 leads) and patient data (67 leads vs 32 and 16 leads).

MAIN RESULTS

The proposed method allowed an improvement in non-invasive estimation of the atria HDF. For the models the median relative errors were 7.14% for the wavelet-based algorithm vs 60.00% for the Welch method; in patients, the errors were 10.03% vs 12.66%, respectively. The wavelet method outperformed the Welch approach in correct estimations of atrial HDFs in models (81.82% vs 45.45%, respectively) and patients (66.67% vs 41.67%). A low positive BSPM-DF map correlation was seen between the techniques (0.47 for models and 0.63 for patients), highlighting the overall differences in DF distributions. The wavelet-based algorithm was more robust to white Gaussian noise, residual ventricular activity and harmonics, and presented more consistent results in lead layouts with low spatial resolution.

SIGNIFICANCE

Estimation of atrial HDFs using BSPM is improved by the proposed wavelet-based algorithm, helping to increase the non-invasive diagnostic ability in AF.

P1055REMARKABLE REMOVALS OF BETA-2-MICROGLOBULIN AND PHOSPHATE WITH SHORT-DAILY HOME HEMODIALYSIS USING LOW DIALYSATE FLOW RATE

Background and Aims

Short-daily hemodialysis (HD) with low-dialysate volume is an appealing portable dialysis approach for home use. Although this type of HD has proved being effective for the volume control and the clearance of low molecular-weight uremic toxins, limited data are available on the impact on the removal rates of other uremic toxins like β2-microglobulin (β2M) or phosphate (P), whose clearance is limited by sequestration into compartments, poor diffusion, high time-dependency, or protein binding. We evaluated the impact of short-daily HD with slow dialysate flow rate on the removal of solutes of different molecular weights and distribution volumes.

Method

Single-session and weekly balances of β2M, P, urea, and creatinine were prospectively assessed with total dialysate collection and serum measurements before and after 341 dialysis sessions (mean dialysate volume: 30963 ± 862 mL; mean length of dialysis session: 153 ± 8 min) in 31 stable patients (female; 9, 29 %; mean age: 55.6 ± 13.6 y; dry weight: 74.9 ± 13.3 kg) undergoing short-daily home HD with NxStage cycler, between July 2014 and October 2019. The mean blood flow rate was 365 ± 17 mL/min, whereas the mean dialysate flow rate was 194 ± 12 mL/min.

Results

Single-session β2M, P, urea, and creatinine removals were 0.138 ± 0.050 g, 0.610 ± 0.161 g, 18.89 ± 6.07 g and 1.07 ± 0.31 g, respectively, whereas the reduction rates (%) were 38.0 ± 13.0, 46.8 ± 8.6, 48.2 ± 7.0 and 46.6 ± 6.6, for β2M, P, urea and creatinine, respectively. The estimated weekly β2M, P, urea and creatinine removals in HDD patients dialyzing 5-6 days per week were comparable with 4-h in-center thrice-weekly on-line hemodiafiltration according to previous studies (Table 1).

Conclusion

Treating patients with short-daily HD with low-dialysate volume at a 5-6 days per week prescription may achieve an efficient weekly β2M and P removal.

Phase singularity point tracking for the identification of typical and atypical flutter patients: A clinical-computational study

Atrial Flutter (AFL) termination by ablating the path responsible for the arrhythmia maintenance is an extended practice. However, the difficulty associated with the identification of the circuit in the case of atypical AFL motivates the development of diagnostic techniques. We propose body surface phase map analysis as a noninvasive tool to identify AFL circuits. Sixty seven lead body surface recordings were acquired in 9 patients during AFL (i.e. 3 typical, 6 atypical). Computed body surface phase maps from simulations of 5 reentrant behaviors in a realistic atrial structure were also used. Surface representation of the macro-reentrant activity was analyzed by tracking the singularity points (SPs) in surface phase maps obtained from band-pass filtered body surface potential maps. Spatial distribution of SPs showed significant differences between typical and atypical AFL. Whereas for typical AFL patients 70.78 ± 16.17% of the maps presented two SPs simultaneously in the areas defined around the midaxialliary lines, this condition was only satisfied in 5.15 ± 10.99% (p < 0.05) maps corresponding to atypical AFL patients. Simulations confirmed these results. Surface phase maps highlights the reentrant mechanism maintaining the arrhythmia and appear as a promising tool for the noninvasive characterization of the circuit maintaining AFL. The potential of the technique as a diagnosis tool needs to be evaluated in larger populations and, if it is confirmed, may help in planning ablation procedures.

Minimal configuration of body surface potential mapping for discrimination of left versus right dominant frequencies during atrial fibrillation

BACKGROUND

Ablation of drivers maintaining atrial fibrillation (AF) has been demonstrated as an effective therapy. Drivers in the form of rapidly activated atrial regions can be noninvasively localized to either left or right atria (LA, RA) with body surface potential mapping (BSPM) systems. This study quantifies the accuracy of dominant frequency (DF) measurements from reduced-leads BSPM systems and assesses the minimal configuration required for ablation guidance.

METHODS

Nine uniformly distributed lead sets of eight to 66 electrodes were evaluated. BSPM signals were registered simultaneously with intracardiac electrocardiograms (EGMs) in 16 AF patients. DF activity was analyzed on the surface potentials for the nine leads configurations, and the noninvasive measures were compared with the EGM recordings.

RESULTS

Surface DF measurements presented similar values than panoramic invasive EGM recordings, showing the highest DF regions in corresponding locations. The noninvasive DFs measures had a high correlation with the invasive discrete recordings; they presented a deviation of <0.5 Hz for the highest DF and a correlation coefficient of >0.8 for leads configurations with 12 or more electrodes.

CONCLUSIONS

Reduced-leads BSPM systems enable noninvasive discrimination between LA versus RA DFs with similar results as higher-resolution 66-leads system. Our findings demonstrate the possible incorporation of simplified BSPM systems into clinical planning procedures for AF ablation.

Review: Application of Pulsed Electric Fields in Egg and Egg Derivatives

This work overviews works published on the application of pulsed electric fields (PEF) in egg and egg derivatives, grouped by subject, and arranged chronologically in terms of the factor studied (microorganisms, quality aspects, shelf life and structural changes in gel formation properties). The inactivation of microorganisms by PEF in egg is very considerable, 3.5 decimal reductions in egg white were achieved by PEF in Salmonella enteritidis, 5.5 log reductions of Listeria innocua by means of a synergistic effect of PEF and nisin in liquid whole egg, and 5.6 log reductions of Escherichia coli in beaten fresh liquid egg by PEF treatment applied continuously or discontinuously in five steps. The shelf life of PEF-treated fresh liquid egg was extended to 4 weeks in refrigeration, and quality (colour, viscosity and sensory attributes) was not affected by PEF treatment. PEF treatment did not cause notable changes in proteins in a solution of ovalbumin and dialysed fresh egg white. However, some structural changes and functional modifications were observed in fresh egg white as a result of PEF treatment. The texture and microstructure of gels were affected by the application of PEF, and therefore PEF treatment conditions in egg white must be optimised to minimise possible modifications.

[Confusion as a presentation symptom of pseudomigraine with pleocytosis in a paediatric patient]

Transient headache and neurological deficits with cerebrospinal fluid lymphocytic pleocytosis (Handl) syndrome is a rare condition of unknown origin that is characterized by episodes of severe headache, transient neurological deficits that recur over less than 3 months, and lymphocytic pleocytosis in CSF. We report the case of a 14 year-old girl who presented with headache and vomiting that lasted 4 days, later combined with a clinical presentation of confusion, with a decrease in the level of consciousness, aphasia, peripheral facial paralysis, ataxia and fever for 24 hours. CSF analysis showed pleocytosis (110 cells/ml) and proteinorrachia (87 mg/dl). Electroencephalogram in the acute time showed generalized slowing, and later a focal slowing in the left hemisphere. She suffered 7 episodes of migraine (severe headache and vomiting) in the following two months, remaining asymptomatic thereafter. This is the first pediatric case published in the literature that presents with an agitated and/or confused state. This condition must be considered in the differential diagnosis of patients with headache and acute altered level of consciousness, in order to avoid prolonged treatments or unnecessary invasive testing.

Efecto del extracto etanólico de la tara sobre el estrés oxidativo y enzimas marcadoras de daño hepático en un modelo animal

Objetivos: Determinar el daño oxidativo en suero y la toxicidad hepática tras la ingesta del extracto etanólico de la Cesalpinia spinosa (tara), en un modelo animal. Diseño: Estudio experimental, transversal. Institución: Centro de Investigación de Bioquímica y Nutrición, Facultad de Medicina, UNMSM. Material biológico: Ratas machos, extracto del fruto de la tara, molida y seca. Intervenciones: Se formó 5 grupos de 6 ratas cada uno, de 250 g aproximadamente. Se les administró el extracto de tara por 45 días, a la dosis que se indica en los grupos (mg/kg peso): G1 (control), G2 (100), G3 (200), G4 (400), G5 (800). Transcurrido el tiempo de tratamiento, se sacrificó las ratas. Principales medidas de resultados: En suero: lipoperoxidación (MDA), transaminasas (GOT y GPT) y gamma-glutamil transferasa (γ-GGT). Resultados: Los niveles de MDA (μmol/L) fueron: 5,02; 4,25; 4,83; 5,05; 5,55, correspondientes a los grupos G1 al G5, respectivamente. Las actividades de transaminasas (GOT y GPT) y γ-GGT fueron muy similares al grupo control (G1), con variación no significativa. Conclusiones: La administración del extracto de tara protege a las ratas del daño oxidativo a concentraciones bajas. No existe aparente daño hepático de la tara, a la dosis administrada.

Ribotipificación de Escherichia coli y Klebsiella pneumoniae productoras de BLEEs, aisladas de pacientes hospitalizados y de la comunidad del Instituto Nacional de Salud del Niño

Objetivos: Investigar la epidemiología molecular y clínica de E. coli y K. pneumoniae productoras de beta lactamasas de espectro extendido (BLEE), de muestras procedentes de pacientes hospitalizados y de pacientes de la comunidad. Diseño: Descriptivo. institución: Centro de Investigación de Bioquímica y Nutrición, Facultad de Medicina, UNMSM; Servicio de Microbiología Instituto Nacional de Salud del Niño. Participantes: Muestra poblacional de Lima, de 31 personas. intervenciones: Extracción de ADN genómico de E. coli, amplificación de la región espaciadora intergénica entre los genes 16S y 23S con primers 1406f y 23Sr, detección por electroforesis en agarosa al 1,5% y tinción con bromuro de etidio. Se realizó el análisis de los patrones de huella de ADN mediante análisis del espaciador intergénico ribosomal (RISA). Para el agrupamiento jerárquico de los patrones se usó el algoritmo de agrupamiento UPGMA Principales medidas de resultados: Diferencias en los patrones RISA de E. coli. resultados: En las muestras analizadas, se detectó diferencias en los patrones RISA. Empleando el coeficiente de similitud de Jaccard, se formó agrupaciones con seis variables. Conclusiones: El nivel de resolución del análisis RISA fue lo suficientemente sensible para detectar diferencias entre las cepas de E. coli.

Vitamin D deficiency and vitamin D therapy in chronic hepatitis C

BACKGROUND

Vitamin D has immunomodulatory properties, exerts an anti-hepatitis C virus (HCV) effect in vitro and improves response to interferon-based therapy in patients with chronic hepatitis C (CHC). Low serum levels of 25(OH) vitamin D [25(OH)D] are frequently found in CHC patients and seem to be related to more advanced stages of liver fibrosis. The study aims to establish the incidence of vitamin D deficiency in Spanish patients with CHC, its possible relation with features of liver damage and with the IL28B gene polymorphism, and the immediate effect of vitamin D therapy on CHC-related analytical variables.

MATERIALS AND METHODS

Baseline serum 25(OH)D levels were measured in 108 consecutive CHC patients (60 men, age 54.3 ± 10.5 yrs). Results of transient elastography and of IL28B rs12979860C/T genotype were available in 89 and 95 patients, respectively. Forty one patients with insufficient levels of 25(OH)D received vitamin D supplements and were re-evaluated thereafter.

RESULTS

Deficiency of vitamin D (< 20 μg/dL) and suboptimal levels (20-30 μg/mL) were detected in 36.1% and 40.9% of patients, respectively. No relationships were found between 25(OH)D levels and biochemical liver tests, fibrosis stage and IL28B genotype. Vitamin D therapy normalized 25(OH)D levels in all treated patients, but did not modify significantly HCV-RNA serum levels or biochemical tests.

CONCLUSIONS

Vitamin D deficiency is common in Spanish patients with CHC but it is related neither to biochemical and virological variables nor with the fibrosis stage and IL28B polymorphism. Vitamin D therapy has no immediate effect on HCV-RNA serum levels.

The monoterpene limonene in orange peels attracts pests and microorganisms

Plant volatiles include terpenoids, which are generally involved in plant defense, repelling pests and pathogens and attracting insects for herbivore control, pollination and seed dispersal. Orange fruits accumulate the monoterpene limonene at high levels in the oil glands of their fruit peels. When limonene production was downregulated in orange fruits by the transgenic expression of a limonene synthase (CitMTSE1) in the antisense configuration, these fruits were resistant to the fungus Penicillium digitatum (Pers.) Sacc. and the bacterium Xanthomonas citri subsp. citri and were less attractive to the medfly pest Ceratitis capitata. These responses were reversed when the antisense transgenic orange fruits were treated with limonene. To gain more insight into the role of the limonene concentration in fruit responses to pests and pathogens, we attempted to overexpress CitMTSE1 in the sense configuration in transgenic orange fruits. Only slight increases in the amount of limonene were found in sense transgenic fruits, maybe due to the detrimental effect that excessive limonene accumulation would have on plant development. Collectively, these results suggest that when limonene reaches peak levels as the fruit develops, it becomes a signal for pest and pathogen attraction, which facilitate access to the fruit for pulp consumers and seed dispersers.

Comparison of phalangeal bone mineral content and density between the dominant and non-dominant sides

OBJECTIVES

Compared to the non-dominant side, higher bone mineral content (BMC) and density (BMD) have been demonstrated in the forearm bones in the dominant side. Clinicians are compelled to scan the dominant side when deformities or artifacts are found in the non-dominant side. This study was done to evaluate the differences in phalangeal BMC and BMD, measured using accuDXA, between the dominant and non-dominant hands. Design and participants A group of 333 subjects, comprising 267 healthy volunteers (185 women and 82 men) and 66 women with rheumatoid arthritis. Phalangeal BMD and BMC, were measured using accuDEXA, both in the non-dominant and dominant hands. Main results BMC and BMD showed strong correlations between the two sides (r = 0.95, p < 0.001 for both). Compared to the non-dominant side, dominant side BMC was 5% higher (mean values =1.54 and 1.47, mean difference = 0.064, 95% CI for the mean difference = 0.048-0.081 g, p < 0.001) and BMD was 4% higher (mean values = 0.480 and 0.463, mean difference = 0.018, 95% CI for the mean difference = 0.014-0.021 g/cm2, p < 0.001). In the subgroup analysis, percentage differences of BMD between the two sides were found to be similar among men (n=82), women (n=251), people below 50 years (n=24), people above 50 years (n=122) and also among patients with rheumatoid arthritis (n=66). Conclusions When the non-dominant hand is not suitable for scanning, the clinician should consider scanning the dominant hand instead. However, the differences in BMD between the two hands should be taken into consideration when interpreting results.

[Acute necrotizing esophagitis in an unstable patient]

Acute necrotizing esophagitis or black esophagus is a rare affection, described in the medical literature since 1990. Although its mechanism is not fully understood, ischemic compromise appears to be the fundamental physiopathological factor. When acute necrotizing esophagitis is found in the endoscopic study of an upper digestive haemorrhage, the prognosis is good. We present a case in which diagnosis of black esophagus was an endoscopic finding, secondary to a situation of underlying hemodynamic instability, with a fatal outcome.