Scaling Analysis of an Image Encryption Scheme Based on Chaotic Dynamical Systems.

Despite that many image encryption systems based on chaotic or hyperchaotic systems have been proposed to protect different kinds of information, it has been crucial to achieve as much security as possible in such systems. In this sense, we numerically implement a known image encryption system with some variants, making special emphasis when two operations are considered in the scrambling stage. The variants of such an encryption system are based on some hyperchaotic systems, which generated some substitution boxes and the keys of the system. With the aim to have a more complete evaluation, some internal stages of the image encryption scheme have been evaluated by using common statistical tests, and also the scaling behavior of the encrypted images has been calculated by means of a two-dimensional detrended fluctuation analysis (2D-DFA). Our results show that the image encryption systems that include two operations or transformations in the scrambling stage present a better performance than those encryption systems that consider just one operation. In fact, the 2D-DFA approach was more sensitive than some common statistical tests to determine more clearly the impact of multiple operations in the scrambling process, confirming that this scaling method can be used as a perceptual security metric, and it may contribute to having better image encryption systems.

Influence of oral anticoagulation on stroke severity and outcomes: A propensity score matching case-control study.

BACKGROUND: Oral anticoagulants (OAC) such as vitamin K antagonists (VKA) and direct-acting OACs (DOAC) remain the mainstay for prevention of cardioembolic stroke. The influence of previous OAC treatment on stroke severity and outcomes is not well stablished. We compared patients with incident cardioembolic strokes according to pre-stroke treatment. METHODS: Retrospective observational study of patients with cardioembolic stroke. Demographic data, vascular risk factors, pre-stroke treatments, reperfusion therapies and outcomes were analyzed. Propensity score matching of baseline characteristics was used to compare case-control samples across different treatment groups: adequate OAC vs no OAC; inadequate VKA vs no OAC; adequate VKA vs inadequate VKA; adequate VKA vs DOAC. RESULTS: 462 patients (76 ±â€¯11.6 years) included. 255 (55%) had a known major cardioembolic source, but only 151 (59%) of them were under OAC upon admission (127 VKA, 24 DOAC). Four patients received VKA for other reasons. Of those taking VKA, 91 (69%) had an inadequate anticoagulation. After propensity score matching, we found no significant differences in stroke severity across the different groups. Patients receiving DOAC had lower mortality at 3 months (8% vs 33%, p = .033) and higher successful recanalization rates after thrombectomy (100% vs 25%, p = .033) compared with adequate VKA anticoagulation. CONCLUSIONS: DOAC treatment significantly reduced mortality at three months compared with adequate VKA anticoagulation. Further studies are needed to confirm its influence on endovascular thrombectomy outcomes.

Methylmercury decreases cellular excitability by a direct blockade of sodium and calcium channels in bovine chromaffin cells: an integrative study.

Methylmercury, a potent environmental pollutant responsible for fatal food poisoning, blocked calcium channels of bovine chromaffin cells in a time- and concentration-dependent manner with an IC50 of 0.93 µM. This blockade was not reversed upon wash-out and was greater at more depolarising holding potentials (i.e. 21 % at -110 mV and 60 % at -50 mV, after 3 min perfusion with methylmercury). In ω-toxins-sensitive calcium channels, methylmercury caused a higher blockade of I Ba than in ω-toxins-resistant ones, in which a lower blockade was detected. The sodium current was also blocked by acute application of methylmercury in a time- and concentration-dependent manner with an IC50 of 1.05 µM. The blockade was not reversed upon wash-out of the drug. The drug inhibited sodium current at all test potentials and shows a shift of the I-V curve to the left of about 10 mV. Intracellular dialysis with methylmercury caused no blockade of calcium or sodium channels. Voltage-dependent potassium current was not affected by methylmercury. Calcium- and voltage-dependent potassium current was also drastically depressed. This blockade was related to the prevention of Ca(2+) influx through voltage-dependent calcium channels coupled to BK channels. Under current-clamp conditions, the blockade of ionic current present during the generation and termination of action potentials led to a drastic alteration of cellular excitability. The application of methylmercury greatly reduced the shape and the number of electrically evoked action potentials. Taken together, these results point out that the neurotoxic action evoked by methylmercury may be associated to alteration of cellular excitability by blocking ionic currents responsible for the generation and termination of action potentials.

[High incidence of hyperestrogenemia and dyslipidemia in a group of infertile men]. / Elevada incidencia de hiperestrogenemia y de dislipidemia en un grupo de hombres infértiles.

The aim of this paper is to describe metabolic and endocrine alterations in the male, partners of infertile couples. One hundred and six consecutive men were taken in order to analyze their serum samples. Each serum sample was analyzed by duplicate for luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), free-testosterone (T), 17 alpha-hydroxyprogesterone (17OHP), androstenedione (A), dehydroepiandrosterone-sulphate (DHEA-S), prolactin (PRL), insulin, glucose, total cholesterol and triclylcerides. The data analysis evidenced different metabolic or endocrine alterations in the group. A dysplipidemia incidence of 65% was found (isolated hypercholesterolemia, isolated triglyceridemia or both), where 80% of these patients were younger than 40 years. There was no correlation with obesity, overweight any endocrine alteration and the type of sperm alterations. There was a positive correlation between E2 and FSH (r = 0.67, p < 0.0001) in the group of 106 patients, which remained significant in the group of hyperestrogenic men (n = 27, r = 0.68, p < 0.0001), but not in men with normal serum estrogen levels (n = 79, r = 0.10, NS). Other alterations: obesity in 18%, overweight in 30.2%, diabetes mellitus 4.7%, glucose intolerance 15%, hypertension 26% (14/53), hypergonadotropic hypogonadism 3.8% (one of them with an Emty Sella syndrome). Unexpectedly only nine patients (8.4%) out of the 106 consecutive patients recluted did not have any of the metabolic or endodrine abnormalities here described. These are more significant since 83% of the patients are younger than 40 years. The most interesting non previously described finding was the positive correlation observed between E2 and FSH when estradiol levels exceeds 50 pg/mL.

Alteración del metabolismo de la glucosa durante la gestación: experiencia institucional / Glucose metabolism alteration during gestation: institutional experience

La heterogeneidad clínica de la Diabetes Mellitus (DM) se manifiesta también durante la gestación, ya que ésta puede complicarse con una DM ya diagnosticada o que es diagnosticada por primera vez durante un embarazo, presentándose con diversos garados de alteración de la glucemia, que son clasificados como Diabetes Mellitus Gestacional o como Alteración gestacional de la curva de tolerancia oral a la glucosa, de acuerdo con los criterios internacionalmente aceptados. Independientemente del momento en que se haya establecido el diagnóstico en la madre, el producto de la gestación probablemente desde el momento mismo de la concepción, está sujeto a un mayor riesgo de aborto, malformaciones congénitas, complicaciones metabólicas perinatales y de muerte, riesgos que parecen estar en relación directa con el momento de establecimiento, el grado y el tiempo de duración del descontrol metabólico materno (hiperglucemia básicamente) y las consecuentes adaptaciones del producto (hiperinsulinemia). Estudiamos en forma retrospectiva el resultado del embarazo de 412 mujeres complicado con algún tipo de alteración en el metabolismo de los carbohidratos, atendidos en nuestro servicio. Los resultados evidenciaron una frecuencia alta de DM gestacional (42.2 por ciento) y de diabetes tipo II (35.9 por ciento) dentro del grupo estudiado, así como concordancia con lo reportado en lo que respecta a los antecedentes personales y familiares de las pacientes diagnosticadas antes del embarazo. Por otro lado, el tipo de las complicaciones obstétricas y perinatales fueron las mismas a lo informado, sin embargo, en nuestro grupo hubo una mayor frecuencia de polihidramnios, toxemia e infección de vías urinarias, con una menor frecuencia solo de cetoacidosis; igualmente fue mayor la incidencia de malformaciones congénitas en los productos. La frecuencia de complicaciones de los recién nacidos fue semejante a lo reportado, con discreto predominio en los hijos de madres diagnosticadas como diabéticas antes de la gestación. Concluimos que entre nuestras pacientes con algún tipo de alteración en el metabolismo de los carbohidratos durante la gestación, parece haber una mayor frecuencia de diabetes gestacional y de diabetes tipo II se inició en nuestras pacintes en edades más tempranas con respecto a lo descrito por otros autores. Destaca la frecuencia alta de malformaciones congénitas dentro del grupo completo y más aún entre los hijops de madres catalogadas como portadoras de diabetes gest