Ratiometric Temperature Sensing Using Highly Coupled Seven-Core Fibers.

In this paper, a ratiometric approach to sensing temperature variations is shown using specialty fiber optic devices. We analyzed the transmission response of cascaded segments of multicore fibers (MCFs), and dissimilar lengths were found to generate an adequate scheme for ratiometric operation. The perturbation of optical parameters in the MCFs translates to a rich spectral behavior in which some peaks increase their intensity while others decrease their intensity. Thus, by selecting opposite-behavior peaks, highly sensitive ratiometric measurements that provide robustness against spurious fluctuations can be performed. We implemented this approach using seven-core fiber (SCF) segments of 5.8 cm and 9.9 cm. To test the system's response under controlled perturbations, we heated one of the segments from ambient temperature up to 150 °C. We observed defined peaks with opposite behavior as a function of temperature. Two pairs of peaks within the interrogation window were selected to perform ratiometric calculations. Ratiometric measurements exhibited sensitivities 6-14 times higher than single-wavelength measurements. A similar trend with enhanced sensitivity in both peak pairs was obtained. In contrast to conventional interferometric schemes, the proposed approach does not require expensive facilities or micrometric-resolution equipment. Moreover, our approach has the potential to be realized using commercial splicers, detectors, and filters.

A review of cardiac troponin I detection by surface enhanced Raman spectroscopy: Under the spotlight of point-of-care testing.

Cardiac troponin I (cTnI) is a biomarker widely related to acute myocardial infarction (AMI), one of the leading causes of death around the world. Point-of-care testing (POCT) of cTnI not only demands a short turnaround time for its detection but the highest accuracy levels to set expeditious and adequate clinical decisions. The analytical technique Surface-enhanced Raman spectroscopy (SERS) possesses several properties that tailor to the POCT format, such as its flexibility to couple with rapid assay platforms like microfluidics and paper-based immunoassays. Here, we analyze the strategies used for the detection of cTnI by SERS considering POCT requirements. From the detection ranges reported in the reviewed literature, we suggest the diseases other than AMI that could be diagnosed with this technique. For this, a section with information about cardiac and non-cardiac diseases with cTnI release, including their release kinetics or cut-off values are presented. Likewise, POCT features, the use of SERS as a POCT technique, and the biochemistry of cTnI are discussed. The information provided in this review allowed the identification of strengths and lacks of the available SERS-based point-of-care tests for cTnI and the disclosing of requirements for future assays design.

Vernier effect using in-line highly coupled multicore fibers.

We demonstrate optical fiber sensors based on highly coupled multicore fibers operating with the optical Vernier effect. The sensors are constructed using a simple device incorporating single-mode fibers (SMFs) and a segment of a multicore fiber. In particular, we evaluated the performance of a sensor based on a seven-core fiber (SCF) spliced at both ends to conventional SMFs, yielding a versatile arrangement for realizing Vernier-based fiber sensors. The SMF-SCF-SMF device can be fabricated using standard splicing procedures and serve as a "building block" for both, reflection and transmission sensing configurations. As demonstrated with our experimental results, the Vernier arrangements can yield a ten-fold increase in sensitivity for temperature measurements compared to a conventional single SMF-SCF-SMF device, thereby confirming the enhanced sensitivity that can be attained with this optical effect. Furthermore, through theoretical analysis, we obtain the relevant parameters that must be optimized in order to achieve an optimal sensitivity for a specific application. Our findings thus provide the necessary guidelines for constructing Vernier-based sensors with all-fiber devices based on highly coupled multicore optical fibers, which constitutes an ideal framework to develop highly sensitive fiber sensors for different applications.

A Review on SERS-Based Detection of Human Virus Infections: Influenza and Coronavirus.

The diagnosis of respiratory viruses of zoonotic origin (RVsZO) such as influenza and coronaviruses in humans is crucial, because their spread and pandemic threat are the highest. Surface-enhanced Raman spectroscopy (SERS) is an analytical technique with promising impact for the point-of-care diagnosis of viruses. It has been applied to a variety of influenza A virus subtypes, such as the H1N1 and the novel coronavirus SARS-CoV-2. In this work, a review of the strategies used for the detection of RVsZO by SERS is presented. In addition, relevant information about the SERS technique, anthropozoonosis, and RVsZO is provided for a better understanding of the theme. The direct identification is based on trapping the viruses within the interstices of plasmonic nanoparticles and recording the SERS signal from gene fragments or membrane proteins. Quantitative mono- and multiplexed assays have been achieved following an indirect format through a SERS-based sandwich immunoassay. Based on this review, the development of multiplex assays that incorporate the detection of RVsZO together with their specific biomarkers and/or secondary disease biomarkers resulting from the infection progress would be desirable. These configurations could be used as a double confirmation or to evaluate the health condition of the patient.

El Quigong en la intervención de la depresión, la ansiedad, y el estrés psicológico laboral / The Quigong in the intervention of depression, anxiety, and psychological stress at work

El impacto de los dramáticos cambios multidimensionales ocasionado por la globalización genera un proceso histórico crítico que impacta al tejido social, sometiendo a muchas poblaciones, a un deterioro de su calidad de vida y de sus posibilidades de acceso a la atención sanitaria. Asimismo están expuestos a tensiones crónicas que pueden desbordar las capacidades y mecanismos de adaptación de las personas. La Medicina Tradicional China tiene más de 5.000 años de práctica empírica y abarca cinco componentes: fitoterapia, dietética, masajes, acupuntura y el Quigong. Su rol terapéutico ha sido reconocido por la OMS, quien ha diseñado estrategias para promover su integración al sistema sanitario de todos los países. Se eligió el componente Quigong para revisar trabajos científicos donde se implementaron sus prácticas en el tratamiento de la Depresión, la Ansiedad y el Estrés psicológico laboral. Los resultados de los estudios revisados concluyeron que existen evidencias significativas de que el Quigong puede mejorar la clínica de pacientes con diagnóstico de Depresión, Ansiedad y estrés laboral. Asimismo, los autores de los trabajos realizados coinciden en la necesidad de proseguir la línea de investigación relativa a las aplicaciones del Quigong como terapia preventiva y curativa en estrés psicológico, ansiedad y depresión.

The impact of the dramatic multidimensional changes caused by globalization generates a critical historical process that impacts the social fabric, subjecting many populations to a deterioration in their quality of life and their possibilities of access to health care. They are also exposed to chronic tensions that can overwhelm people's capacities and adaptation mechanisms. Traditional Chinese Medicine has more than 5.000 years of empirical practice and includes five components: phytotherapy, dietetics, massage, acupuncture and Quigong. Its therapeutic role has been recognized by the WHO, which has designed strategies to promote its integration into the health system of all countries. The Quigong component was chosen to review scientific works where its practices were implemented in the treatment of Depression, Anxiety and Occupational Psychological Stress. The results of the studies reviewed concluded that there is significant evidence that Quigong can improve the clinic of patients diagnosed with Depression, Anxiety, and occupational stress. Likewise, the authors of the works carried out agree on the need to continue the line of research regarding the applications of Quigong as preventive and curative therapy in psychological stress, anxiety and depression.

All-Fiber Measurement of Surface Tension Using a Two-Hole Fiber.

An all-fiber approach is presented to measure surface tension. The experimental realization relies on the use of a specialty fiber, a so-called two-hole fiber (THF), which serves a two-fold purpose: providing a capillary channel to produce bubbles while having the means to measure the power reflected at the end facet of the fiber core. We demonstrate that provided a controlled injection of gas into the hollow channels of the THF, surface tension measurements are possible by simply tracking the Fresnel reflection at the distal end of the THF. Our results show that the characteristic times involved in the bubble formation process, from where the surface tension of the liquids under test is retrieved, can be measured from the train of pulses generated by the continuous formation and detachment of bubbles.

Indirect Quantification of Glyphosate by SERS Using an Incubation Process With Hemin as the Reporter Molecule: A Contribution to Signal Amplification Mechanism.

The indirect determination of the most used herbicide worldwide, glyphosate, was achieved by the SERS technique using hemin chloride as the reporter molecule. An incubation process between hemin and glyphosate solutions was required to obtain a reproducible Raman signal on SERS substrates consisting of silicon decorated with Ag nanoparticles (Si-AgNPs). At 780 nm of excitation wavelength, SERS spectra from hemin solutions do not show extra bands in the presence of glyphosate. However, the hemin bands increase in intensity as a function of glyphosate concentration. This allows the quantification of the herbicide using as marker band the signal associated with the ring breathing mode of pyridine at 745 cm-1. The linear range was from 1 × 10-10 to 1 × 10-5 M and the limit of detection (LOD) was 9.59 × 10-12 M. This methodology was successfully applied to the quantification of the herbicide in honey. From Raman experiments with and without silver nanoparticles, it was possible to state that the hemin is the species responsible for the absorption in the absence or the presence of the herbicide via vinyl groups. Likewise, when the glyphosate concentration increases, a subtle increase occurs in the planar orientation of the vinyl group at position 2 in the porphyrin ring of hemin over the silver surface, favoring the reduction of the molecule. The total Raman signal of the hemin-glyphosate incubated solutions includes a maximized electromagnetic contribution by the use of the appropriate laser excitation, and chemical contributions related to charge transfer between silver and hemin, and from resonance properties of Raman scattering of hemin. Incubation of the reporter molecule with the analyte before the conjugation with the SERS substrate has not been explored before and could be extrapolated to other reporter-analyte systems that depend on a binding equilibrium process.

Incidence of the adjacent segment disease treated at the issemym medical center / Incidência da doença do segmento adjacente tratada no centro médico issemym / Incidencia de la enfermedad del segmento adyacente tratada en el centro médico issemym

ABSTRACT Objective: To determine the incidence and rate of disc degeneration adjacent to a lumbar fusion, as well as to analyze possible risk factors for its development. Methods: A retrospective study of a level of evidence IIB case series of 125 patients diagnosed with lumbar canal stenosis and spondylolisthesis, who underwent surgery from January 2011 to December 2016, with subsequent instrumentation and posterolateral fusion and outpatient follow-up in which the symptomatology and radiographic findings were evaluated to establish the diagnosis and management. Results: Twelve patients with adjacent segment disease were identified, with an incidence of 9.6%, higher both among female patients and in the seventh decade of life. The most frequent pathology was canal stenosis (42.4%), the most affected level was L4 / L5, and the procedure most associated with the prevalence of adjacent level degeneration was L4-L5 posterior transpedicular instrumentation. Conclusions: Sagittalization of the facet joint was a constant factor in all patients with involvement of the adjacent disc. The main clinical findings were treatment-resistant root pain and radiographic alterations characterized by spondylolisthesis, facet osteoarthritis and intervertebral disc herniation. Level of Evidence IIB; Retrospective study.

RESUMO Objetivo: Determinar a incidência e a taxa de degeneração do disco adjacente, bem como analisar possíveis fatores de risco de degeneração do disco adjacente à fusão lombar. Métodos: Foi realizado um estudo retrospectivo de série de casos com nível de evidência IIB, com uma amostra de 125 pacientes com diagnóstico de estenose de canal lombar e espondilolistese, que foram operados no período de janeiro de 2011 a dezembro de 2016, com instrumentação posterior e fusão posterolateral e acompanhamento ambulatorial, no qual se avaliou a sintomatologia e os achados radiográficos para estabelecer o diagnóstico e o tratamento. Resultados: Foram identificados 12 pacientes com doença do segmento adjacente, com incidência de 9,6%, com maior frequência no sexo feminino e na sétima década de vida. A patologia mais frequente foi estenose do canal (42,4%). O nível mais afetado foi L4/L5, e o procedimento mais relacionado com a prevalência do nível adjacente foi a instrumentação transpedicular posterior em L4/L5. Conclusões: A sagitalização das facetas articulares tem sido um fator constante em todos os pacientes, com envolvimento do disco adjacente. Os principais achados clínicos são dor radicular resistente ao tratamento e alterações radiográficas caracterizadas por espondilolistese, artrose facetária e hérnia de disco intervertebral. Nível de Evidência IIB; Estudo retrospectivo.

RESUMEN Objetivo: Determinar la incidencia y tasa de degeneración del disco adyacente, así como analizar posibles factores de riesgo de desarrollar degeneración del disco adyacente a una fusión lumbar. Métodos: Se realizó un estudio retrospectivo de serie de casos con nivel de Evidencia IIB, con una muestra de 125 pacientes con diagnósticos de canal lumbar estrecho y espondilolistesis, intervenidos quirúrgicamente en el periodo de enero del 2011 a diciembre del 2016, con instrumentación posterior y fusión posterolateral, con seguimiento en consulta externa en el cual se evaluó la sintomatología y hallazgos radiográficos para establecer el diagnóstico y manejo. Resultados: Se identificaron 12 pacientes con enfermedad del segmento adyacente. Con una incidencia de 9,6%, con mayor incidencia en el sexo femenino y mayor incidencia en la séptima década de la vida. La patología más frecuente ha sido la estenosis de canal (42,4%). El nivel de mayor afectación fue en L4/L5, y el procedimiento más relacionado con la prevalencia de nivel adyacente fue la instrumentación posterior transpedicular L4/L5. Conclusiones: La sagitalización de las facetas articulares ha sido un factor constante en todos los pacientes, con afectación del disco adyacente. Los principales hallazgos clínicos son dolor radicular resistente al tratamiento y alteraciones radiográficas caracterizadas por espondilolistesis, artrosis facetaria y hernia de disco intervertebral. Nivel de Evidencia IIB; Estudio retrospectivo.

Emerging pollutant treatments in wastewater: Cases of antibiotics and hormones.

Because of the intensive use of pharmaceutical substances in human life, studies on the detection of these chemical compounds and their metabolites as pollutants in water bodies are continuously reported. Some pharmaceutical agents are associated with adverse effects to aquatic life, even at very low concentrations (ng L-1 to µg L-1). For instance, the presence of antibiotics and hormones has been associated with increasing proliferation of antibiotic resistant pathogens and feminization and masculinization of some aquatic organisms. Currently, new attempts are being made to minimize or fully remove these types of pollutants from aquatic systems to protect the environment and human health. In this regard, physicochemical and biological treatments are among the most promising technologies for the treatment of wastewater containing pharmaceutical pollutants. These treatments are green alternatives for the degradation of hazardous organic compounds into nontoxic by-products. Here, we review some of the physicochemical and biological treatment methods used for the removal of the most extensively used antibiotics and hormones. Enzymatic oxidation, photocatalysis and electrochemical oxidation are described in terms of the aforementioned pharmaceutically active compounds (PhACs). The use of membrane technologies to separate different groups of antibiotics and hormones prior to biologic or physicochemical treatment methods is also addressed.

First-passage times for pattern formation in nonlocal partial differential equations.

We describe the lifetimes associated with the stochastic evolution from an unstable uniform state to a patterned one when the time evolution of the field is controlled by a nonlocal Fisher equation. A small noise is added to the evolution equation to define the lifetimes and to calculate the mean first-passage time of the stochastic field through a given threshold value, before the patterned steady state is reached. In order to obtain analytical results we introduce a stochastic multiscale perturbation expansion. This multiscale expansion can also be used to tackle multiplicative stochastic partial differential equations. A critical slowing down is predicted for the marginal case when the Fourier phase of the unstable initial condition is null. We carry out Monte Carlo simulations to show the agreement with our theoretical predictions. Analytic results for the bifurcation point and asymptotic analysis of traveling wave-front solutions are included to get insight into the noise-induced transition phenomena mediated by invading fronts.

Highly Sensitive Liquid Core Temperature Sensor Based on Multimode Interference Effects.

A novel fiber optic temperature sensor based on a liquid-core multimode interference device is demonstrated. The advantage of such structure is that the thermo-optic coefficient (TOC) of the liquid is at least one order of magnitude larger than that of silica and this, combined with the fact that the TOC of silica and the liquid have opposite signs, provides a liquid-core multimode fiber (MMF) highly sensitive to temperature. Since the refractive index of the liquid can be easily modified, this allows us to control the modal properties of the liquid-core MMF at will and the sensor sensitivity can be easily tuned by selecting the refractive index of the liquid in the core of the device. The maximum sensitivity measured in our experiments is 20 nm/°C in the low-temperature regime up to 60 °C. To the best of our knowledge, to date, this is the largest sensitivity reported for fiber-based MMI temperature sensors.

The Underlying Social Dynamics of Paradigm Shifts.

We develop here a multi-agent model of the creation of knowledge (scientific progress or technological evolution) within a community of researchers devoted to such endeavors. In the proposed model, agents learn in a physical-technological landscape, and weight is attached to both individual search and social influence. We find that the combination of these two forces together with random experimentation can account for both i) marginal change, that is, periods of normal science or refinements on the performance of a given technology (and in which the community stays in the neighborhood of the current paradigm); and ii) radical change, which takes the form of scientific paradigm shifts (or discontinuities in the structure of performance of a technology) that is observed as a swift migration of the knowledge community towards the new and superior paradigm. The efficiency of the search process is heavily dependent on the weight that agents posit on social influence. The occurrence of a paradigm shift becomes more likely when each member of the community attaches a small but positive weight to the experience of his/her peers. For this parameter region, nevertheless, a conservative force is exerted by the representatives of the current paradigm. However, social influence is not strong enough to seriously hamper individual discovery, and can act so as to empower successful individual pioneers who have conquered the new and superior paradigm.

Stochastic model predicts evolving preferences in the Iowa gambling task.

Learning under uncertainty is a common task that people face in their daily life. This process relies on the cognitive ability to adjust behavior to environmental demands. Although the biological underpinnings of those cognitive processes have been extensively studied, there has been little work in formal models seeking to capture the fundamental dynamic of learning under uncertainty. In the present work, we aimed to understand the basic cognitive mechanisms of outcome processing involved in decisions under uncertainty and to evaluate the relevance of previous experiences in enhancing learning processes within such uncertain context. We propose a formal model that emulates the behavior of people playing a well established paradigm (Iowa Gambling Task - IGT) and compare its outcome with a behavioral experiment. We further explored whether it was possible to emulate maladaptive behavior observed in clinical samples by modifying the model parameter which controls the update of expected outcomes distributions. Results showed that the performance of the model resembles the observed participant performance as well as IGT performance by healthy subjects described in the literature. Interestingly, the model converges faster than some subjects on the decks with higher net expected outcome. Furthermore, the modified version of the model replicated the trend observed in clinical samples performing the task. We argue that the basic cognitive component underlying learning under uncertainty can be represented as a differential equation that considers the outcomes of previous decisions for guiding the agent to an adaptive strategy.

Effect of abdominoplasty in the lipid profile of patients with dyslipidemia.

Introduction. Dyslipidemia like other chronic degenerative diseases is pandemic in Latin America and around the world. A lot of patients asking for body contouring surgery can be sick without knowing it. Objective. Observe the lipid profile of patients with dyslipidemia, before and three months after an abdominoplasty. Methods. Patients candidate to an abdominoplasty without morbid obesity were followed before and three months after the surgery. We compared the lipid profile, glucose, insulin, and HOMA (cardiovascular risk marker) before and three months after the surgery. We used Student's t test to compare the results. A P value less than 0.05 was considered as significant. Results. Twenty-six patients were observed before and after the surgery. At the third month, we found only statistical differences in LDL and triglyceride values (P 0.04 and P 0.03). The rest of metabolic values did not reach statistical significance. Conclusion. In this group of patients with dyslipidemia, at the third month, only LDL and triglyceride values reached statistical significances. There is no significant change in glucose, insulin, HOMA, cholesterol, VLDL, or HDL.

Designing a gelatin/chitosan/hyaluronic acid biopolymer using a thermophysical approach for use in tissue engineering.

Cell culture on biopolymeric scaffolds has provided treatments for tissue engineering. Biopolymeric mixtures based on gelatin (Ge), chitosan (Ch) and hyaluronic acid (Ha) have been used to make scaffolds for wound healing. Thermal and physical properties of scaffolds prepared with Ge, Ch and Ha were characterized. Thermal characterization was made by using differential scanning calorimetry (DSC), and physical characterization by gas pycnometry and scanning electron microscopy. The effects of Ge content and cross-linking on thermophysical properties were evaluated by means of a factorial experiment design (central composite face centered). Gelatin content was the main factor that affects the thermophysical properties (microstructure and thermal transitions) of the scaffold. The effect of Ge content of the scaffolds for tissue engineering was studied by seeding skin cells on the biopolymers. The cell attachment was not significantly modified at different Ge contents; however, the cell growth rate increased linearly with the decrease of the Ge content. This relationship together with the thermophysical characterization may be used to design scaffolds for tissue engineering.

Beneficial effects of human altruism.

In this work we review converging evidence from several lines of research which suggests that altruism in humans can be intrinsically rewarding. Various investigations illustrate how human altruism can have beneficial effects on health and wellbeing. In this contribution we propose a model that includes positive effects of altruism. These beneficial effects lead to significant changes in the dynamics of the system, favouring higher levels of altruism and facilitating abrupt changes towards cooperation. In the present model, social modulation occurs at both individual and collective levels. The potential beneficial role of altruism proposed here may account for its occurrence among non-kin and beyond reciprocity.

Characterization of a gelatin/chitosan/hyaluronan scaffold-polymer

Gelatin, chitosan and hyaluronic acid are natural components used to prepare polymeric scaffold in tissue engineering. The physical properties of these materials confer an appropriate microenvironment for cells, which can be used as a regeneration system for skin and cartilage. In this work, we prepared and characterized a Gelatin/Chitosan/Hyaluronan lyophilized-polymer. Physical properties of lyophilized-polymer changed slightly with moisture, but when polymer was totally hydrated the elasticity changed significantly. Thermophysical characterisation indicated that temperatures higher than 30ºC could modify irreversibly the polymeric matrix probably due to protein denaturation. Besides, we used the polymer as scaffold to prepare a biosynthetic-skin, reporting biological behaviour and its mechanical properties.

The effect of an autologous cellular gel-matrix integrated implant system on wound healing.

BACKGROUND: This manuscript reports the production and preclinical studies to examine the tolerance and efficacy of an autologous cellular gel-matrix integrated implant system (IIS) aimed to treat full-thickness skin lesions. METHODS: The best concentration of fibrinogen and thrombin was experimentally determined by employing 28 formula ratios of thrombin and fibrinogen and checking clot formation and apparent stability. IIS was formed by integrating skin cells by means of the in situ gelification of fibrin into a porous crosslinked scaffold composed of chitosan, gelatin and hyaluronic acid. The in vitro cell proliferation within the IIS was examined by the MTT assay and PCNA expression. An experimental rabbit model consisting of six circular lesions was utilized to test each of the components of the IIS. Then, the IIS was utilized in an animal model to cover a 35% body surface full thickness lesion. RESULTS: The preclinical assays in rabbits demonstrated that the IIS was well tolerated and also that IIS-treated rabbit with lesions of 35% of their body surface, exhibited a better survival rate (p = 0,06). CONCLUSION: IIS should be further studied as a new wound dressing which shows promising properties, being the most remarkable its good biological tolerance and cell growth promotion properties.

Vegetation pattern formation in a fog-dependent ecosystem.

Vegetation pattern formation is a striking characteristic of several water-limited ecosystems around the world. Typically, they have been described on runoff-based ecosystems emphasizing local interactions between water, biomass interception, growth and dispersal. Here, we show that this situation is by no means general, as banded patterns in vegetation can emerge in areas without rainfall and in plants without functional root (the Bromeliad Tillandsia landbeckii) and where fog is the principal source of moisture. We show that a simple model based on the advection of fog-water by wind and its interception by the vegetation can reproduce banded patterns which agree with empirical patterns observed in the Coastal Atacama Desert. Our model predicts how the parameters may affect the conditions to form the banded pattern, showing a transition from a uniform vegetated state, at high water input or terrain slope to a desert state throughout intermediate banded states. Moreover, the model predicts that the pattern wavelength is a decreasing non-linear function of fog-water input and slope, and an increasing function of plant loss and fog-water flow speed. Finally, we show that the vegetation density is increased by the formation of the regular pattern compared to the density expected by the spatially homogeneous model emphasizing the importance of self-organization in arid ecosystems.

Individual and combined effects of ApoE and MTHFR 677C/T polymorphisms on cognitive performance in Spanish adolescents: the AVENA study.

OBJECTIVE: To examine the individual and combined associations of ApoE and MTHFR 677C/T polymorphisms with cognitive performance in adolescents. STUDY DESIGN: The study comprised 412 Spanish adolescents (13 to 18.5 years of age). Cognitive performance (verbal, numeric and reasoning abilities, and an overall score) was measured by the Spanish-version of the SRA-Test of Educational-Ability. RESULTS: We observed no differences in the cognitive performance study variables in adolescents carrying or not carrying the ApoE epsilon4 variant. Adolescents without the MTHFR 677TT genotype had significantly better cognitive performance than their TT peers. The analysis of the combined effect of these polymorphisms revealed that those individuals carrying both the ApoE epsilon4 variant and the MTHFR 677TT genotype had significantly worse cognitive performance than their peers with other genotype combinations. These findings were independent of sex, age pubertal status, socioeconomic status, physical activity, and skipping breakfast. CONCLUSIONS: The results of the present study suggest that the ApoE epsilon4 alone is not associated with cognitive performance in adolescents. Individuals with the MTHFR 677TT genotype had slightly impaired cognitive performance, whereas we observed a combined effect of both the ApoE epsilon4 variant and the MTHFR 677TT genotype on cognitive performance. More research is needed in larger population samples to corroborate our findings.