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1.
Orv Hetil ; 164(16): 630-635, 2023 Apr 23.
Artículo en Húngaro | MEDLINE | ID: mdl-37087729

RESUMEN

INTRODUCTION AND OBJECTIVE: For patients requiring prolonged mechanical ventilation, tracheostomy becomes necessary, which may be performed through surgical or percutaneous methods. In this study, we used three different methods of percutaneous dilatational tracheostomy. Our goal was to identify anthropometric parameters relevant for the correct position of the tracheostomy tube. MATERIAL AND METHODS: Randomized, controlled observational study was performed on 118 cadavers. Three different tracheostomy methods were used: the Griggs (n = 37), the Griggs modified by Élo (n = 45), and the Ciaglia's Blue Rhino (n = 36). The neck circumference, jugulomental distance, and mid-upper arm circumference were measured on each cadaver. We assessed whether the aforementioned parameters related with the appropriate positioning of the tracheostomy tube Results: Significant correlation was found (p = 0.0287) between mid-upper arm circumference and incorrect tracheostomy tube position (below the fourth tracheal cartilage ring). We identified the value of 30 cm of mid-upper arm circumference as the ideal cut-off for predicting tube malposition (sensitivity: 63.63%, specificity: 60.22%). CONCLUSION: When planning percutaneous tracheostomy, it is important to measure the anthropometric parameters. If mid-upper arm circumference is 30 cm or higher we recommend other tests and/or ENT (ear, nose, and throat) consultation. Orv Hetil. 2023; 164(16): 630-635.


Asunto(s)
Tráquea , Traqueostomía , Humanos , Traqueostomía/métodos , Respiración Artificial , Procedimientos Quirúrgicos Vasculares , Dilatación/métodos
2.
J Assist Reprod Genet ; 38(12): 3223-3232, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34704166

RESUMEN

PURPOSE: We sought to determine whether pregnancies conceived in those with male factor infertility have unique placental pathology profiles compared to those undergoing infertility treatments for other indications. METHODS: This was a retrospective cohort study of placental pathology from 464 live births conceived from autologous fresh IVF cycles at an academic fertility center from 2004 to 2017. Placental pathology was compared between live births arising from patients with male factor infertility alone and those with another infertility diagnosis. Placental outcomes were compared with parametric or non-parametric tests; logistic regression was performed to account for potential confounders. RESULTS: Compared to cycles performed for a non-male factor diagnosis, male factor infertility cycles had a higher mean paternal age (38.2 years vs. 36.5 years, p < 0.001), a higher female mean BMI (24.3 vs. 23.3 kg/m2, p = 0.01), and a lower day 3 follicle stimulating hormone (FSH) level (6.8 vs. 7.3 IU/mL, p = 0.02). The mean numbers of embryos transferred, and day of transfer were similar between groups, and more cycles used ICSI in the male factor infertility group (90.6% vs. 22.5%, p < 0.001). Placental pathology in our adjusted model was similar between the male factor and non-male factor groups. In our unadjusted subgroup analysis, cycles for male factor using ICSI appeared to lead to more small placentas by weight compared to cycles performed with conventional insemination (45.8% < 10th percentile vs. 18.8%, p = 0.04). CONCLUSION: Male factor infertility is not associated with significantly different placental pathology compared to other infertility diagnoses.


Asunto(s)
Infertilidad Masculina/patología , Enfermedades Placentarias/patología , Placenta/patología , Adulto , Peso al Nacer/fisiología , Transferencia de Embrión/métodos , Femenino , Fertilización/fisiología , Fertilización In Vitro/métodos , Humanos , Nacimiento Vivo , Masculino , Hombres , Embarazo , Índice de Embarazo , Estudios Retrospectivos
3.
Helminthologia ; 55(3): 256-260, 2018 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31662655

RESUMEN

A survey of entomopathogenic nematodes was conducted in Croatia between 2016 and 2017. The steinernematids were recovered in two out of 100 soil samples from agricultural land characterized as loamy soils with acidic reaction. Molecular and morphological identification was used to distinguish the nematodes. The isolates were identified as two different strains conspecific with Steinernema feltiae. The variations in morphometrical characteristics of infective juveniles (IJs) and males were observed among Croatian strains and with the original description. The analysis of ITS region revealed the greatest similarity of Croatian strains with Slovenian B30 and English A2 strains, which together comprised a monophyletic group in evolutionary analysis. This is the first record of steinernematids, namely S. feltiae in Croatia.

4.
Hum Reprod ; 32(9): 1846-1854, 2017 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-28854726

RESUMEN

STUDY QUESTION: Is pre-treatment alcohol and caffeine intake associated with infertility treatment outcomes among women undergoing ART? SUMMARY ANSWER: Low to moderate alcohol and caffeine intakes in the year prior to infertility treatment were not related to ART outcomes. WHAT IS KNOWN ALREADY: Alcohol and caffeine intake have been found to be associated with infertility in some studies. Nevertheless, data on their relation with outcomes of infertility treatments are scarce and inconsistent. STUDY DESIGN, SIZE, DURATION: We included 300 women (493 ART cycles) from the Environment and Reproductive Health Study, an ongoing cohort study (2006-2016). PARTICIPANTS/MATERIALS, SETTING, METHODS: Pre-treatment intakes of alcohol and caffeine were assessed retrospectively using a validated food frequency questionnaire. Intermediate and clinical endpoints of ART were abstracted from electronic medical records. Generalized linear mixed models with random intercepts to account for multiple ART cycles per woman were used to evaluate the association with ART outcomes adjusting for age, BMI, smoking status, infertility diagnosis, protocol type, race, dietary patterns, and calories, vitamin B12 and folate intake. MAIN RESULTS AND THE ROLE OF CHANCE: Median (range) pre-treatment alcohol and caffeine intakes were 5.6 (0.0-85.8) g/day and 124.9 (0.3-642.2) mg/day, respectively. The adjusted percentage of initiated cycles resulting in live birth (95% CI) for women in increasing categories of pre-treatment alcohol intake was 34% (20, 52%) for non-consumers, 46% (36, 57%) for 0.1-6 g/day, 41% (29, 53%) for 6.1-12 g/day, 42% (31, 55%) for 12.1-24 g/day, and 41% (22, 63%) for >24 g/day (P, trend = 0.87). The adjusted percentage of cycles resulting in live birth (95% CI) for women in increasing categories of caffeine intake was 46% (36-57%) for <50 mg/day, 44% (29, 60%) for 50.1-100 mg/day, 42% (31, 53%) for 100.1-200 mg/day, 40% (28, 53%) for 200.1-300 mg/day and 40% (21, 63%) for >300 mg/day (P, trend = 0.34). When specific types of alcoholic and caffeinated beverages were evaluated, no relations with ART treatment outcomes were observed. LIMITATIONS, REASONS FOR CAUTION: Residual confounding by other diet and lifestyle factors cannot be ruled out owing to the observational nature of this study. It is also unclear how generalizable these results are to women who are conceiving without the assistance of ART. WIDER IMPLICATIONS OF THE FINDINGS: Our results provide reassurance that low to moderate intakes of alcohol (e.g. ≤12 g/day) and caffeine (e.g. <200 mg/day) in the year prior to infertility treatment initiation do not have an adverse effect on intermediate or clinical outcomes of ART. STUDY FUNDING/COMPETING INTEREST(S): The authors are supported by National Institutes of Health (NIH) grants ES022955, R01ES009718, R01ES000002, P30DK46200 and L50-HD085359. No conflicts of interest to declare. TRIAL REGISTRATION NUMBER: NCT00011713.


Asunto(s)
Consumo de Bebidas Alcohólicas , Cafeína , Infertilidad Femenina/terapia , Técnicas Reproductivas Asistidas , Adulto , Estudios de Cohortes , Femenino , Humanos , Embarazo , Resultado del Embarazo , Índice de Embarazo , Estudios Retrospectivos , Resultado del Tratamiento
5.
Andrology ; 5(2): 354-361, 2017 03.
Artículo en Inglés | MEDLINE | ID: mdl-28187518

RESUMEN

Much of the literature on the impact of male caffeine and alcohol intake on reproductive outcomes has utilized semen quality as a proxy for male fertility, although semen parameters have a limited predictive value for spontaneous pregnancy. The objective of this study was to investigate whether male caffeine and alcohol intakes are associated with semen parameters and assisted reproductive technology outcome. The Environment and Reproductive Health Study, an ongoing prospective cohort study, enrolls subfertile couples presenting for treatment at an academic fertility center (2007-2012). A total of 171 men with 338 semen analyses and 205 assisted reproductive technology cycles were included in this analysis. Diet was assessed using a 131-item food frequency questionnaire. Mixed models adjusting for potential confounders were used to evaluate the relationships of male caffeine and alcohol intakes with semen parameters and assisted reproductive technology outcomes. There was no association between male caffeine and alcohol intake and semen quality. Male caffeine intake was negatively related to live birth after assisted reproductive technologies (p-trend < 0.01), and male alcohol intake was positively related to live birth after assisted reproductive technologies (p-trend = 0.04). Adjusted live birth rate among couples with a male partner in the highest quartile of caffeine intake (≥272 mg/day) compared to couples with a male partner in the lowest quartile of intake (<99 mg/day) was 19% vs. 55%, respectively, p < 0.01. In terms of alcohol intake, adjusted live birth rate among couples with a male partner in the highest quartile of alcohol intake (≥22 g/day) compared to couples with a male partner in the lowest quartile of intake (<3 g/day) was 61% vs. 28%, respectively, p = 0.05. In conclusion, male pre-treatment caffeine and alcohol intakes were associated with live birth after assisted reproductive technologies, but not with semen parameters, among fertility patients.


Asunto(s)
Consumo de Bebidas Alcohólicas/fisiopatología , Cafeína/administración & dosificación , Fertilidad/fisiología , Infertilidad/terapia , Motilidad Espermática/fisiología , Adulto , Femenino , Fertilización In Vitro , Humanos , Masculino , Embarazo , Índice de Embarazo , Estudios Prospectivos , Análisis de Semen , Recuento de Espermatozoides
6.
Neuroimage ; 139: 439-449, 2016 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-27374370

RESUMEN

Movements result from a complex interplay of multiple brain regions. These regions are assembled into distinct functional networks depending on the specific properties of the action. However, the nature and details of the dynamics of this complex assembly process are unknown. In this study, we sought to identify key markers of the neural processes underlying the preparation and execution of motor actions that always occur irrespective of differences in movement initiation, hence the specific neural processes and functional networks involved. To this end, EEG activity was continuously recorded from 18 right-handed healthy participants while they performed a simple motor task consisting of button presses with the left or right index finger. The movement was performed either in response to a visual cue or at a self-chosen, i.e., non-cued point in time. Despite these substantial differences in movement initiation, dynamic properties of the EEG signals common to both conditions could be identified using time-frequency and phase locking analysis of the EEG data. In both conditions, a significant phase locking effect was observed that started prior to the movement onset in the δ-θ frequency band (2-7Hz), and that was strongest at the electrodes nearest to the contralateral motor region (M1). This phase locking effect did not have a counterpart in the corresponding power spectra (i.e., amplitudes), or in the event-related potentials. Our finding suggests that phase locking in the δ-θ frequency band is a ubiquitous movement-related signal independent of how the actual movement has been initiated. We therefore suggest that phase-locked neural oscillations in the motor cortex are a prerequisite for the preparation and execution of motor actions.


Asunto(s)
Sincronización Cortical , Ritmo Delta , Corteza Motora/fisiología , Movimiento , Ritmo Teta , Adulto , Electroencefalografía , Potenciales Evocados , Femenino , Dedos , Humanos , Masculino , Actividad Motora , Desempeño Psicomotor , Adulto Joven
7.
Curr Med Res Opin ; 32(1): 23-36, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-26414386

RESUMEN

BACKGROUND: This article summarizes the outcome from an international consensus meeting, which took place in Vienna on 4 November 2014. SCOPE: The aim of the meeting was to provide the state of the art on the pathophysiology and treatment of acute pain with special emphasis on nimesulide, a non-steroidal anti-inflammatory drug (NSAID) indicated for the treatment of acute pain and primary dysmenorrhea. Besides the data on the mechanisms of acute inflammatory pain and on the efficacy and safety of nimesulide in patients affected by different forms of acute pain, the clinical experience of attending experts was discussed based on selected case reports. RESULTS: The members of this consensus group recognized that nimesulide is a NSAID highly effective in the treatment of several painful situations with an acute inflammatory component including primary dysmenorrhea. Although safety concerns regarding nimesulide have emerged in recent years, both robust new epidemiological data and clinical experience confirm a positive benefit/risk profile of nimesulide in the treatment of several forms of acute pain. CONCLUSIONS: The members of this international consensus group concluded that nimesulide, when used appropriately, remains a particularly valuable and safe option for the treatment of several conditions characterized by the presence of acute inflammatory pain because of the rapid onset of the analgesic action, and the positive evidence-based benefit/risk profile.


Asunto(s)
Dolor Agudo/tratamiento farmacológico , Antiinflamatorios no Esteroideos/uso terapéutico , Sulfonamidas/uso terapéutico , Enfermedad Hepática Inducida por Sustancias y Drogas/etiología , Comorbilidad , Femenino , Humanos , Masculino , Sulfonamidas/efectos adversos , Sulfonamidas/farmacología
8.
J Neurophysiol ; 115(2): 887-906, 2016 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-26581871

RESUMEN

Insect locomotion requires the precise coordination of the movement of all six legs. Detailed investigations have revealed that the movement of the legs is controlled by local dedicated neuronal networks, which interact to produce walking of the animal. The stick insect is well suited to experimental investigations aimed at understanding the mechanisms of insect locomotion. Beside the experimental approach, models have also been constructed to elucidate those mechanisms. Here, we describe a model that replicates both the tetrapod and tripod coordination pattern of three ipsilateral legs. The model is based on an earlier insect leg model, which includes the three main leg joints, three antagonistic muscle pairs, and their local neuronal control networks. These networks are coupled via angular signals to establish intraleg coordination of the three neuromuscular systems during locomotion. In the present three-leg model, we coupled three such leg models, representing front, middle, and hind leg, in this way. The coupling was between the levator-depressor local control networks of the three legs. The model could successfully simulate tetrapod and tripod coordination patterns, as well as the transition between them. The simulations showed that for the interleg coordination during tripod, the position signals of the levator-depressor neuromuscular systems sent between the legs were sufficient, while in tetrapod, additional information on the angular velocities in the same system was necessary, and together with the position information also sufficient. We therefore suggest that, during stepping, the connections between the levator-depressor neuromuscular systems of the different legs are of primary importance.


Asunto(s)
Extremidades/fisiología , Insectos/fisiología , Locomoción , Modelos Neurológicos , Animales , Fenómenos Biomecánicos , Extremidades/inervación , Articulaciones/inervación , Articulaciones/fisiología , Músculo Esquelético/inervación , Músculo Esquelético/fisiología
9.
Andrology ; 3(4): 702-8, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-26097060

RESUMEN

Male factor etiology may be a contributing factor in up to 60% of infertility cases. Dietary intake of phytoestrogens has been related to abnormal semen quality and hormone levels. However, its effect on couple fecundity is still unclear. Intake of soy products was assessed in 184 men from couples undergoing infertility treatment with in vitro fertilization. Couples were recruited between February 2007 and May 2014 and prospectively followed to document treatment outcomes including fertilization, implantation, clinical pregnancy and live birth. Multivariate generalized linear mixed models with random intercepts, binomial distribution and logit link function were used to examine this relation while accounting for repeated treatment cycles and adjusting for potential confounders. Male partner's intake of soy foods and soy isoflavones was unrelated to fertilization rates, the proportions of poor quality embryos, accelerated or slow embryo cleavage rate, and implantation, clinical pregnancy and live birth. The adjusted live birth rates per initiated cycle (95% CI) for partners of men in increasing categories of soy food intake were 0.36 (0.28-0.45), 0.42 (0.29-0.56), 0.36 (0.24-0.51), and 0.37 (0.24-0.52), respectively. Soy food intake in men was not related to clinical outcomes among couples presenting at an infertility clinic. Data on the relation between phytoestrogens and male reproductive potential remain scarce and additional research is required to clarify its role in human reproduction.


Asunto(s)
Fertilidad , Fertilización In Vitro/estadística & datos numéricos , Alimentos de Soja/efectos adversos , Adulto , Femenino , Humanos , Isoflavonas/efectos adversos , Masculino , Embarazo , Índice de Embarazo , Estudios Prospectivos
10.
J Comput Neurosci ; 38(3): 601-16, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25904469

RESUMEN

Inter-segmental coordination is crucial for the locomotion of animals. Arthropods show high variability of leg numbers, from 6 in insects up to 750 legs in millipedes. Despite this fact, the anatomical and functional organization of their nervous systems show basic similarities. The main similarities are the segmental organization, and the way the function of the segmental units is coordinated. We set out to construct a model that could describe locomotion (walking) in animals with more than 6 legs, as well as in 6-legged animals (insects). To this end, we extended a network model by Daun-Gruhn and Tóth (Journal of Computational Neuroscience, doi: 10.1007/s10827-010-0300-1 , 2011). This model describes inter-segmental coordination of the ipsilateral legs in the stick insect during walking. Including an additional segment (local network) into the original model, we could simulate coordination patterns that occur in animals walking on eight legs (e.g., crayfish). We could improve the model by modifying its original cyclic connection topology. In all model variants, the phase relations between the afferent segmental excitatory sensory signals and the oscillatory activity of the segmental networks played a crucial role. Our results stress the importance of this sensory input on the generation of different stable coordination patterns. The simulations confirmed that using the modified connection topology, the flexibility of the model behaviour increased, meaning that changing a single phase parameter, i.e., gating properties of just one afferent sensory signal was sufficient to reproduce all coordination patterns seen in the experiments.


Asunto(s)
Crustáceos/fisiología , Ganglios de Invertebrados/fisiología , Locomoción/fisiología , Modelos Neurológicos , Redes Neurales de la Computación , Animales , Generadores de Patrones Centrales , Simulación por Computador , Retroalimentación Fisiológica , Insectos/fisiología , Vías Nerviosas/citología , Vías Nerviosas/fisiología , Sensación/fisiología , Sinapsis/fisiología , Caminata/fisiología
11.
Biochim Biophys Acta ; 1837(9): 1572-80, 2014 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-24508217

RESUMEN

We studied the periodicity of the multilamellar membrane system of granal chloroplasts in different isolated plant thylakoid membranes, using different suspension media, as well as on different detached leaves and isolated protoplasts-using small-angle neutron scattering. Freshly isolated thylakoid membranes suspended in isotonic or hypertonic media, containing sorbitol supplemented with cations, displayed Bragg peaks typically between 0.019 and 0.023Å(-1), corresponding to spatially and statistically averaged repeat distance values of about 275-330 Å⁻¹. Similar data obtained earlier led us in previous work to propose an origin from the periodicity of stroma thylakoid membranes. However, detached leaves, of eleven different species, infiltrated with or soaked in D2O in dim laboratory light or transpired with D2O prior to measurements, exhibited considerably smaller repeat distances, typically between 210 and 230 Å⁻¹, ruling out a stromal membrane origin. Similar values were obtained on isolated tobacco and spinach protoplasts. When NaCl was used as osmoticum, the Bragg peaks of isolated thylakoid membranes almost coincided with those in the same batch of leaves and the repeat distances were very close to the electron microscopically determined values in the grana. Although neutron scattering and electron microscopy yield somewhat different values, which is not fully understood, we can conclude that small-angle neutron scattering is a suitable technique to study the periodic organization of granal thylakoid membranes in intact leaves under physiological conditions and with a time resolution of minutes or shorter. We also show here, for the first time on leaves, that the periodicity of thylakoid membranes in situ responds dynamically to moderately strong illumination. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy.


Asunto(s)
Cloroplastos/ultraestructura , Neutrones , Dispersión del Ángulo Pequeño , Tilacoides/ultraestructura , Aldehídos , Tampones (Química) , Pared Celular/ultraestructura , Hojas de la Planta/ultraestructura
12.
Sex Res Social Policy ; 10(1): 24-34, 2013 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-23439743

RESUMEN

This qualitative study highlights the social dynamics affecting people living with HIV (PLH) in Hungary and in the Central-Eastern European region. The study focused on the special needs and concerns of men living with HIV/AIDS as well as changes in their social relationships and institutional support provision, coping strategies and patterns of social functioning, especially in the context of social stigmatization. Consistent with international qualitative research findings in the field of HIV/AIDS prevention, the present study contributes to a fuller understanding of relationship between sexual behavior, HIV/AIDS related risks and risk perceptions as well as homosexuality-and HIV/AIDS stigma-related social exclusion in a previously under-researched socio-cultural setting. The findings of our study point to several barriers to effective HIV prevention, which should be overcome to improve the present situation by lessening the adverse effects of HIV/AIDS-and homosexuality-related stigma within the gay community, the general population and especially among service providers. One of the main barriers is the lack of public health programs specifically targeting MSM in Hungary, where the predominant mode of HIV transmission remains sex between men.

13.
J Neurophysiol ; 109(3): 679-91, 2013 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-23136343

RESUMEN

The coordination of the movement of single and multiple limbs is essential for the generation of locomotion. Movement about single joints and the resulting stepping patterns are usually generated by the activity of antagonistic muscle pairs. In the stick insect, the three major muscle pairs of a leg are the protractor and retractor coxae, the levator and depressor trochanteris, and the flexor and extensor tibiae. The protractor and retractor move the coxa, and thereby the leg, forward and backward. The levator and depressor move the femur up and down. The flexor flexes, and the extensor extends the tibia about the femur-tibia joint. The underlying neuronal mechanisms for a forward stepping middle leg have been thoroughly investigated in experimental and theoretical studies. However, the details of the neuronal and mechanical mechanisms driving a stepping single leg in situations other than forward walking remain largely unknown. Here, we present a neuromechanical model of the coupled three joint control system of the stick insect's middle leg. The model can generate forward, backward, or sideward stepping. Switching between them is achieved by changing only a few central signals controlling the neuromechanical model. In kinematic simulations, we are able to generate curve walking with two different mechanisms. In the first, the inner middle leg is switched from forward to sideward and in the second to backward stepping. Both are observed in the behaving animal, and in the model and animal alike, backward stepping of the inner middle leg produces tighter turns than sideward stepping.


Asunto(s)
Modelos Neurológicos , Movimiento , Músculo Esquelético/fisiología , Neuronas/fisiología , Animales , Fenómenos Biomecánicos , Extremidades/inervación , Extremidades/fisiología , Femenino , Insectos , Músculo Esquelético/inervación , Caminata
14.
Phys Rev E Stat Nonlin Soft Matter Phys ; 86(1 Pt 2): 016322, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-23005540

RESUMEN

Measurements of two-dimensional (2D) temperature fields are performed by an interferometric method during density fingering of the autocatalytic chlorite-tetrathionate reaction in a Hele-Shaw cell. These measures confirm that, because of heat losses through the glass walls of the reactor, the temperature profile across the front is a pulse rather than a front. Moreover, the full 2D temperature field shows the presence in the reactive zone of hot spots where the temperature exceeds the maximum temperature measured in a stable planar front. We investigate here experimentally the increase of temperature in the hot spots when the composition of the reactants is varied to increase the exothermicity of the reaction. We back up these experimental observations by nonlinear simulations of a reaction-diffusion-convection model which show that the maximum temperature reached in the system depends on the intensity of convection.


Asunto(s)
Transferencia de Energía , Modelos Químicos , Termodinámica , Catálisis , Simulación por Computador , Conductividad Térmica
15.
J Neurophysiol ; 107(12): 3267-80, 2012 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-22402652

RESUMEN

The mechanism underlying the generation of stepping has been the object of intensive studies. Stepping involves the coordinated movement of different leg joints and is, in the case of insects, produced by antagonistic muscle pairs. In the stick insect, the coordinated actions of three such antagonistic muscle pairs produce leg movements and determine the stepping pattern of the limb. The activity of the muscles is controlled by the nervous system as a whole and more specifically by local neuronal networks for each muscle pair. While many basic properties of these control mechanisms have been uncovered, some important details of their interactions in various physiological conditions have so far remained unknown. In this study, we present a neuromechanical model of the coupled protractor-retractor and levator-depressor neuromuscular systems and use it to elucidate details of their coordinated actions during forward and backward walking. The switch from protraction to retraction is evoked at a critical angle of the femur during downward movement. This angle represents a sensory input that integrates load, motion, and ground contact. Using the model, we can make detailed suggestions as to how rhythmic stepping might be generated by the central pattern generators of the local neuronal networks, how this activity might be transmitted to the corresponding motoneurons, and how the latter might control the activity of the related muscles. The entirety of these processes yields the coordinated interaction between neuronal and mechanical parts of the system. Moreover, we put forward a mechanism by which motoneuron activity could be modified by a premotor network and suggest that this mechanism might serve as a basis for fast adaptive behavior, like switches between forward and backward stepping, which occur, for example, during curve walking, and especially sharp turning, of insects.


Asunto(s)
Insectos/fisiología , Locomoción/fisiología , Modelos Neurológicos , Músculo Esquelético/fisiología , Potenciales de Acción/fisiología , Animales , Extremidad Inferior/inervación , Extremidad Inferior/fisiología , Neuronas Motoras/fisiología , Músculo Esquelético/inervación , Periodicidad
16.
Langmuir ; 27(8): 4742-8, 2011 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-21410189

RESUMEN

We report results of extensive experimental and numerical studies on the suspension of water drops deposited on cylindrical pillars having circular and square cross sections and different wettabilities. In the case of circular pillars, the drop contact line is pinned to the whole edge contour until the drop collapses due to the action of gravity. In contrast, on square pillars, the drops are suspended on the four corners and spilling along the vertical walls is observed. We have also studied the ability of the two geometries to sustain drops and found that if we compare pillars with the same characteristic size, the square is more efficient in pinning large volumes, while if we normalize the volumes to pillar areas, the opposite is true.

17.
Chaos ; 19(2): 023110, 2009 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-19566245

RESUMEN

The spatiotemporal dynamics of vertical autocatalytic fronts traveling horizontally in thin solution layers closed to the air can be influenced by buoyancy-driven convection induced by density gradients across the front. We perform here a combined experimental and theoretical study of the competition between solutal and thermal effects on such convection. Experimentally, we focus on the antagonistic chlorite-tetrathionate reaction for which solutal and thermal contributions to the density jump across the front have opposite signs. We show that in isothermal conditions the heavier products sink below the lighter reactants, providing an asymptotic constant finger shape deformation of the front by convection. When thermal effects are present, the hotter products, on the contrary, climb above the reactants for strongly exothermic conditions. These various observations as well as the influence of the relative weight of the solutal and thermal effects and of the thickness of the solution layer on the dynamics are discussed in terms of a two-dimensional reaction-diffusion-convection model parametrized by a solutal R(C) and a thermal R(T) Rayleigh number.

18.
Clin Nephrol ; 70(2): 159-62, 2008 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-18793532

RESUMEN

The role of severe a1-antitrypsin (A1AT) deficiency in the predisposition of early-onset pulmonary emphysema and juvenile hepatic cirrhosis is well-established. Associated glomerulonephritis is unusual although it is well-recognized in children and young adults with the severe phenotype. We report the first adult case of A1AT deficiency presenting with nephrotic syndrome secondary to IgA nephropathy and explore the direct role of A1AT deposits in the pathogenesis of the renal involvement.


Asunto(s)
Glomerulonefritis por IGA/etiología , Síndrome Nefrótico/etiología , Deficiencia de alfa 1-Antitripsina/complicaciones , Anciano de 80 o más Años , Diagnóstico Diferencial , Resultado Fatal , Glomerulonefritis por IGA/diagnóstico , Humanos , Masculino , Síndrome Nefrótico/diagnóstico , Deficiencia de alfa 1-Antitripsina/diagnóstico
19.
Eur J Neurosci ; 26(7): 1832-44, 2007 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-17883416

RESUMEN

Both human investigations and studies in animal models have suggested that abnormalities in GABA(A) receptor function have a potential role in the pathophysiology of absence seizures. Recently we showed that, prior to seizure onset, GABA(A) IPSCs in thalamic reticular (NRT) neurons of genetic absence epilepsy rats from Strasbourg (GAERS) had a 25% larger amplitude, a 40% faster decay and a 45% smaller paired-pulse depression than those of nonepileptic control (NEC) rats. By means of a novel mathematical description, the properties of both GAERS and NEC GABAergic synapses can be mimicked. These model synapses were then used in an NRT network model in order to investigate their potential impact on the neuronal firing patterns. Compared to NEC, GAERS NRT neurons show an overall increase in excitability and a higher frequency and regularity of firing in response to periodic input signals. Moreover, in response to randomly distributed stimuli, the GAERS but not the NEC model produces resonance between 7 and 9 Hz, the frequency range of spike-wave discharges in GAERS. The implications of these results for the epileptogenesis of absence seizures are discussed.


Asunto(s)
Epilepsia Tipo Ausencia/patología , Potenciales Postsinápticos Inhibidores/fisiología , Núcleos Talámicos Intralaminares/patología , Red Nerviosa/fisiopatología , Neuronas/fisiología , Ácido gamma-Aminobutírico/metabolismo , Potenciales de Acción/fisiología , Potenciales de Acción/efectos de la radiación , Animales , Modelos Animales de Enfermedad , Relación Dosis-Respuesta en la Radiación , Estimulación Eléctrica , Modelos Neurológicos , Inhibición Neural/fisiología , Inhibición Neural/efectos de la radiación , Ratas
20.
Acta Vet Hung ; 55(3): 327-31, 2007 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17867460

RESUMEN

The occurrence of a periosteal chondroma (juxtacortical chondroma) in an adult male Uromastyx maliensis is documented for the first time. The chondroma developed near the right shoulder joint from the periosteal membrane, causing partial atrophy in the surrounding skeletal muscles. In the chondroma tissues widespread central necrosis and secondary calcium salt deposition were observed. Monomorphic chondrocytes were irregularly spread in the chondromucin matrix. The lizard had locomotor problems due to irritation of the periosteum and reduced movement of the bones constituting the shoulder joint caused by the chondroma.


Asunto(s)
Neoplasias Óseas/veterinaria , Condroma/veterinaria , Lagartos , Animales , Neoplasias Óseas/epidemiología , Condroma/epidemiología , Resultado Fatal , Masculino
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