Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 79
Filtrar
1.
Eur J Cancer ; 115: 120-127, 2019 07.
Artículo en Inglés | MEDLINE | ID: mdl-31132742

RESUMEN

BACKGROUND: It is generally agreed to centralise treatment of childhood cancers (CCs). We analysed (1) the degree of centralisation of CCs in European countries and 2) the relations between centralisation and survival. PATIENTS AND METHODS: The analysis comprised 4415 CCs, diagnosed between 2000 and 2007 and followed up to the end of 2013, from Belgium, Bulgaria, Finland, Ireland, the Netherlands and Slovenia. All these countries had national population-based cancer registries and were able to provide information on diagnosis, treatment, treatment hospitals, and survival. Each case was then classified according to whether the patient was treated in a high- or a low-volume hospital among those providing CC treatment. A Cox proportional hazard model was used to calculate the relation between volume category and five-year survival, adjusting by age, sex and diagnostic group. RESULTS: The number of hospitals providing treatment for CCs ranged from six (Slovenia) to slightly more than 40 (the Netherlands and Belgium). We identified a single higher volume hospital in Ireland and in Slovenia, treating 80% and 97% of cases, respectively, and three to five major hospitals in the other countries, treating between 65% and 93% of cases. Outcome was significantly better when primary treatment was given in high-volume hospitals compared to low-volume hospitals for central nervous system tumours (relative risk [RR] = 0.71), haematologic tumours (RR = 0.74) and for all CC combined (RR = 0.83). CONCLUSION: Treatment centralisation is associated with survival benefits and should be further strengthened in these countries. New plans for centralisation should include ongoing evaluation.


Asunto(s)
Servicios Centralizados de Hospital/organización & administración , Hospitales de Alto Volumen , Hospitales de Bajo Volumen/organización & administración , Neoplasias/terapia , Servicio de Oncología en Hospital/organización & administración , Adolescente , Edad de Inicio , Niño , Preescolar , Europa (Continente)/epidemiología , Femenino , Disparidades en Atención de Salud/organización & administración , Humanos , Lactante , Recién Nacido , Masculino , Neoplasias/mortalidad , Sistema de Registros , Medición de Riesgo , Factores de Riesgo , Factores de Tiempo , Resultado del Tratamiento
2.
Klin Lab Diagn ; 64(2): 104-110, 2019.
Artículo en Ruso | MEDLINE | ID: mdl-30917252

RESUMEN

As a result of the conducted researches it is shown that 44.1% of urinary tract infections (UTIS) caused by E. coli are accounted for by producers of beta-lactamase of the extended spectrum of action (ESBL). Associated resistance to fluoroquinolones and co-trimoxazole was found in 93.3% of BLRS-producing E. coli strains. All studied strains regardless of ESBL production were sensitive to imipenem, the majority showed sensitivity to ertapenem, gentamicin and resistance to doxycycline. Not producing ESBL strains of E. coli were sensitive to fosfomycin. Comparison of data obtained during testing of isolated cultures on ESBL, study of their sensitivity and resistance to beta-lactams (amoxicillin/clavulanate, ceftazidime, ceftriaxone, cefotaxime, imipenem) indicates the need to test isolates for AmpC products. To this end, during the screening test for ESBL and the method of «double disks¼, along with cephalosporins of III generation, it is necessary to use a phenotypic test for sensitivity to cefepime. The use of test results of E. coli isolates isolated from patients with UTIS for the production of ESBL, ampC enzymes, carbapenemase and sensitivity to AMP will improve the effectiveness of antimicrobial therapy and will help to curb the formation and spread of antimicrobial-resistan strains.


Asunto(s)
Antibacterianos/uso terapéutico , Escherichia coli/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Infecciones Urinarias/tratamiento farmacológico , Cefalosporinas , Farmacorresistencia Bacteriana , Humanos , Infecciones Urinarias/microbiología
3.
SAR QSAR Environ Res ; 28(6): 511-524, 2017 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-28728491

RESUMEN

In Europe, REACH legislation encourages the use of alternative in silico methods such as (Q)SAR models. According to the recent progress of Chemical Substances Control Law (CSCL) in Japan, (Q)SAR predictions are also utilized as supporting evidence for the assessment of bioaccumulation potential of chemicals along with read across. Currently, the effective use of read across and QSARs is examined for other hazards, including biodegradability. This paper describes the results of external validation and improvement of CATALOGIC 301C model based on more than 1000 tested new chemical substances of the publication schedule under CSCL. CATALOGIC 301C model meets all REACH requirements to be used for biodegradability assessment. The model formalism built on scientific understanding for the microbial degradation of chemicals has a well-defined and transparent applicability domain. The model predictions are adequate for the evaluation of the ready degradability of chemicals.


Asunto(s)
Biodegradación Ambiental , Contaminantes Ambientales/química , Sustancias Peligrosas/química , Modelos Biológicos , Análisis de la Demanda Biológica de Oxígeno , Bases de Datos de Compuestos Químicos , Contaminantes Ambientales/metabolismo , Sustancias Peligrosas/metabolismo , Japón , Relación Estructura-Actividad Cuantitativa , Reproducibilidad de los Resultados
4.
Oncogene ; 36(17): 2472-2482, 2017 04 27.
Artículo en Inglés | MEDLINE | ID: mdl-27819677

RESUMEN

Characterizing the complex interplay of cellular processes in cancer would enable the discovery of key mechanisms underlying its development and progression. Published approaches to decipher driver mechanisms do not explicitly model tissue-specific changes in pathway networks and the regulatory disruptions related to genomic aberrations in cancers. We therefore developed InFlo, a novel systems biology approach for characterizing complex biological processes using a unique multidimensional framework integrating transcriptomic, genomic and/or epigenomic profiles for any given cancer sample. We show that InFlo robustly characterizes tissue-specific differences in activities of signalling networks on a genome scale using unique probabilistic models of molecular interactions on a per-sample basis. Using large-scale multi-omics cancer datasets, we show that InFlo exhibits higher sensitivity and specificity in detecting pathway networks associated with specific disease states when compared to published pathway network modelling approaches. Furthermore, InFlo's ability to infer the activity of unmeasured signalling network components was also validated using orthogonal gene expression signatures. We then evaluated multi-omics profiles of primary high-grade serous ovarian cancer tumours (N=357) to delineate mechanisms underlying resistance to frontline platinum-based chemotherapy. InFlo was the only algorithm to identify hyperactivation of the cAMP-CREB1 axis as a key mechanism associated with resistance to platinum-based therapy, a finding that we subsequently experimentally validated. We confirmed that inhibition of CREB1 phosphorylation potently sensitized resistant cells to platinum therapy and was effective in killing ovarian cancer stem cells that contribute to both platinum-resistance and tumour recurrence. Thus, we propose InFlo to be a scalable and widely applicable and robust integrative network modelling framework for the discovery of evidence-based biomarkers and therapeutic targets.


Asunto(s)
Proteína de Unión a Elemento de Respuesta al AMP Cíclico/metabolismo , AMP Cíclico/metabolismo , Resistencia a Antineoplásicos , Neoplasias Ováricas/tratamiento farmacológico , Neoplasias Ováricas/metabolismo , Biología de Sistemas/métodos , Línea Celular Tumoral , Femenino , Redes Reguladoras de Genes/efectos de los fármacos , Humanos , Neoplasias Ováricas/genética , Neoplasias Ováricas/patología , Transducción de Señal/efectos de los fármacos
5.
Arch Pediatr ; 21(9): 953-60, 2014 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-25066700

RESUMEN

This study examines neonatal group B streptococcal (GBS) colonization and its relation to early-onset GBS disease (EOGBSD), based upon the experience of leading obstetrics and gynecology centers in Bulgaria. The objectives of the study were to update neonatal colonization rates and to assess relationships between clinically differentiated cases (culture-proven GBS newborns) and risk factors inherent to the infant and mother, using a computerized file. The neonatal GBS colonization rate ranged from 5.48 to 12.19 per 1000 live births. Maternal-fetal infection (MFI, a provisional clinical diagnosis in culture-proven colonized infants with initial signs of infection that is usually overcome with antibiotic treatment) and/or intrapartum asphyxia (IA) have been demonstrated as the most frequent clinical manifestations, with significant correlations for the primary diagnosis, but not affirmative for the final diagnosis at discharge, resulting from adequate treatment of neonates. MFI and IA were significantly related to prematurity, and reciprocally, prematurity was associated with the risk of MFI, indirectly suggesting that preterm birth or PPROM (preterm premature rupture of membranes, an obstetric indication associated with early labor and delivery, one of the major causes of preterm birth) is a substantial risk factor for EOGBSD. The regression analysis indicated that in the case of a newborn with MFI, a birth weight 593.58 g lower than the birth weight of an infant without this diagnosis might be expected. Testing the inverse relationship, i.e., the way birth weight influences a certain diagnosis (logistic regression) established the presence of a relationship between birth weight categories (degree of prematurity) and the diagnosis of MFI. The proportions and odds ratios, converted into probabilities that a baby would develop MFI, indicate the particularly high risk for newborns with extremely low and very low birth weight: extremely low birth weight (≤1000 g), the probability of developing a MFI is 66%; very low birth weight (1001-1500 g), 81%; low birth weight (the birth weight category including premature and small for gestational age term infants: 1501-2500 g), 40%; normal birth weight (term infants) (>2500 g), 32%. In conclusion, the need to introduce separate categories for early- and late-onset GBS disease in the registration nomenclature of neonatal infectious diseases is highlighted by these results. Drawing up intrapartum antibiotic prophylaxis (IAP) guidelines is also strongly recommended.


Asunto(s)
Infecciones Estreptocócicas/epidemiología , Streptococcus agalactiae , Asfixia Neonatal/epidemiología , Peso al Nacer , Bulgaria/epidemiología , Femenino , Rotura Prematura de Membranas Fetales , Humanos , Recién Nacido de Bajo Peso , Recién Nacido , Transmisión Vertical de Enfermedad Infecciosa , Embarazo , Complicaciones Infecciosas del Embarazo/epidemiología , Nacimiento Prematuro , Factores de Riesgo , Infecciones Estreptocócicas/transmisión
6.
J BUON ; 18(4): 1038-44, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-24344035

RESUMEN

PURPOSE: In Bulgaria, there are over 3700 cases diagnosed with breast cancer annually and over 3300 with gynecological cancers. The purpose of this study was to estimate the burden of breast and gynecological cancers in Bulgaria, analyzing trends of incidence, mortality and survival for the past two decades. METHODS: Data from the Bulgarian National Cancer Registry for women diagnosed with cancer of breast (C50, ICD10), cervix uteri (C53), corpus uteri (C54) and ovary (C56) during 1993 - 2009 were analyzed. Age-standardized incidence and mortality rates (ASR) per 100,000 persons were calculated using the world standard population. Average annual percent changes (AAPC) for 1993-2009 were estimated by Joinpoint regression. The observed survival was analyzed with the Life Table method for two periods: 1993-1997 and 2005-2009. RESULTS: Incidence rates of the most frequent cancers among Bulgarian women are increasing - from 1.7% to 2.6% annually. Mortality rates are decreasing significantly for breast (-0.8% annually) and increasing for corpus uteri cancers (4.9% annually). Survival for all sites increased from 3 to 8% over the study period. We observed greater proportion of cases diagnosed in stage I in 2009 than in 1993, for the 4 sites. CONCLUSION: These results indicate some differences in trends in incidence and mortality of the reviewed sites compared with other European countries, highlighting the need for more strict adherence to integrated treatment standards and the necessity of introduction of population screening programs.


Asunto(s)
Neoplasias de la Mama/epidemiología , Neoplasias de los Genitales Femeninos/epidemiología , Adolescente , Adulto , Distribución por Edad , Factores de Edad , Anciano , Anciano de 80 o más Años , Neoplasias de la Mama/mortalidad , Neoplasias de la Mama/patología , Neoplasias de la Mama/terapia , Bulgaria/epidemiología , Detección Precoz del Cáncer , Femenino , Neoplasias de los Genitales Femeninos/mortalidad , Neoplasias de los Genitales Femeninos/patología , Neoplasias de los Genitales Femeninos/terapia , Humanos , Incidencia , Tablas de Vida , Persona de Mediana Edad , Estadificación de Neoplasias , Valor Predictivo de las Pruebas , Sistema de Registros , Análisis de Supervivencia , Factores de Tiempo , Adulto Joven
7.
Eur J Appl Physiol ; 112(4): 1399-409, 2012 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-21818623

RESUMEN

The mechanism of marked reduction in damage symptoms after repeated bout of similar eccentric contractions is still unknown. The neuronal adaptation leading to reduction of muscle fibre propagation velocity (MFPV) due to increased activation of slow-twitch motor units (MUs), decrease in activation of fast-twitch MUs, and/or increase in MU synchronization was suggested as a cause for lower EMG frequency characteristics. However, the repeated bout effect could occur also after electrically stimulated exercise. Prolonged elevation of cytoplasmic Ca(2+) due to the increased membrane permeability after eccentric contractions was reported. Elevated Ca(2+) induced peripheral changes that included alteration of intracellular action potential and MFPV reduction. We simulated and compared changes in EMG frequency characteristics related to effects of central nervous system (CNS) or to peripheral changes. The simulations were performed for different electrode arrangements and positions. The results showed that the peripheral effects could be similar or even stronger than the effects related to CNS. We hypothesised that the repeated bout effect was a consequence of the adaptation in muscle fibres necessary for avoiding Ca(2+)-induced protein and lipid degradation due to Ca(2+) overload resulting from the increased membrane permeability after eccentric contraction. The possibilities for noninvasive testing of this hypothesis were discussed.


Asunto(s)
Adaptación Fisiológica , Simulación por Computador , Electromiografía , Modelos Biológicos , Contracción Muscular , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/metabolismo , Potenciales de Acción , Análisis de Varianza , Señalización del Calcio , Permeabilidad de la Membrana Celular , Electrodos , Electromiografía/instrumentación , Humanos , Músculo Esquelético/inervación , Procesamiento de Señales Asistido por Computador , Factores de Tiempo
8.
SAR QSAR Environ Res ; 23(1-2): 17-36, 2012 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-22014234

RESUMEN

The new development of the bioconcentration factor (BCF) base-line model of Dimitrov et al. [SAR QSAR Environ. Res. 6 (2005), pp. 531-554] is presented. The model applicability domain was expanded by enlarging the training set of the model up to 705 chemicals. The list of chemical-dependent mitigating factors was expanded by including water solubility of chemicals. The original empirical term for estimating ionization of chemicals was mechanistically analysed using two different approaches. In the first one, the ionization potential of chemicals was estimated based on the acid dissociation constant (pK(a) ). This term was found to be less adequate for inclusion in the ultimate BCF model, due to overestimating ionization of chemicals. The second approach, estimating the ionization as a ratio between distribution and partition coefficients (log P and log D), was found to be more successful. The new ionization term allows modelling of chemicals with both acidic and basic functionalities and chemicals undergoing different degrees of ionization. The significance of the different mitigating factors which can reduce the maximum bioconcentration potential of the chemicals was re-formulated and model parameters re-evaluated.


Asunto(s)
Fenómenos Químicos , Contaminantes Ambientales/metabolismo , Modelos Teóricos , Absorción , Animales , Iones/química , Análisis de los Mínimos Cuadrados , Metabolismo , Modelos Estadísticos , Relación Estructura-Actividad Cuantitativa , Solubilidad , Agua
9.
Akush Ginekol (Sofiia) ; 51(6): 10-21, 2012.
Artículo en Búlgaro | MEDLINE | ID: mdl-23390859

RESUMEN

The results achieved with 80% reduction in the incidence of early-onset neonatal group B streptococcal (GBS) sepsis following the implementation of the preliminary (1996, 2002) and subsequently the revised (2010) guidelines for intrapartum antibiotic prophylaxis imposed the discussion on a large scale of the updated:--algorithms for GBS screening (35-37 weeks of gestation) with the recommended dosage of penicillin-G for intrapartum antibiotic prophylaxis for women having normal labor and delivery;--algorithms for GBS screening and intrapartum antibiotic prophylaxis for women with preterm labor (PPROM) or premature rupture of membranes (PROM);--intrapartum antibiotic prophylaxis regimens for women with penicillin allergy;--algorithm for management of newborns with respect to risk of early-onset GBS disease. The present study is aimed at studying the distribution of the early-onset GBS disease in our country based on the data of leading obstetrics & gynecology clinics and wards. The aim is to diferrentiate clinically the cases and investigate the influence of the known risk factors on the part of the mother. A special accent is put over the microbiological diagnostics of cases in view of CDC expanded recommendations on the laboratory methods for identification of GBS. As a final conclusion the necessity for introduction of an official registration of the early- and late-onset GBS disease in the country is emphasized.


Asunto(s)
Enfermedades del Recién Nacido/diagnóstico , Enfermedades del Recién Nacido/epidemiología , Complicaciones Infecciosas del Embarazo/diagnóstico , Complicaciones Infecciosas del Embarazo/epidemiología , Infecciones Estreptocócicas/diagnóstico , Infecciones Estreptocócicas/epidemiología , Antibacterianos/uso terapéutico , Profilaxis Antibiótica , Bulgaria/epidemiología , Femenino , Humanos , Incidencia , Recién Nacido , Enfermedades del Recién Nacido/tratamiento farmacológico , Penicilina G/uso terapéutico , Embarazo , Complicaciones Infecciosas del Embarazo/tratamiento farmacológico , Factores de Riesgo , Infecciones Estreptocócicas/tratamiento farmacológico , Streptococcus/aislamiento & purificación
10.
SAR QSAR Environ Res ; 22(7-8): 719-55, 2011 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-21999837

RESUMEN

The unprecedented pollution of the environment by xenobiotic compounds has provoked the need to understand the biodegradation potential of chemicals. Mechanistic understanding of microbial degradation is a premise for adequate modelling of the environmental fate of chemicals. The aim of the present paper is to describe abiotic and biotic models implemented in CATALOGIC software. A brief overview of the specificities of abiotic and microbial degradation is provided followed by detailed descriptions of models built in our laboratory during the last decade. These are principally new models based on unique mathematical formalism already described in the first paper of this series, which accounts more adequately than currently available approaches the multipathway metabolic logic in prokaryotes. Based on simulated pathways of degradation, the models are able to predict quantities of transformation products, biological oxygen demand (BOD), carbon dioxide (CO(2)) production, and primary and ultimate half-lives. Interpretation of the applicability domain of models is also discussed.


Asunto(s)
Biotransformación , Simulación por Computador , Contaminantes Ambientales/metabolismo , Contaminantes Ambientales/toxicidad , Xenobióticos/metabolismo , Xenobióticos/toxicidad , Análisis de la Demanda Biológica de Oxígeno , Dióxido de Carbono/metabolismo , Contaminantes Ambientales/química , Redes y Vías Metabólicas , Medición de Riesgo/métodos , Programas Informáticos , Xenobióticos/química
11.
Sci Total Environ ; 408(18): 3811-6, 2010 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-20199798

RESUMEN

The awareness of air, soil and water pollution has driven the search for better methods for the assessment of the environmental fate of industrial chemicals. This paper is focused on the simulation of formation and transformation of metabolites in soil. The key challenges in the development of a simulator for predicting metabolic fate of chemicals in soil are the complexity of the soil compartment and incompleteness of metabolic information. Based on the collected data for metabolic fate of 183 chemicals a set of soil specific transformations were defined and used to develop a simulator for metabolism in soil. The analysis of outliers showed that the low predictability for some chemicals is due to: 1) incomplete documented metabolic pathways with missing intermediates and/or 2) reactions of condensation that are not simulated in the current version of the model. Hence, further improvement of the model requires expanding the metabolism database and further refinement of the logic of metabolic transformations used in the simulator.


Asunto(s)
Monitoreo del Ambiente/métodos , Modelos Químicos , Contaminantes del Suelo/metabolismo , Biodegradación Ambiental , Contaminación Ambiental/estadística & datos numéricos , Predicción , Microbiología del Suelo , Contaminantes del Suelo/química
12.
Sci Total Environ ; 408(18): 3787-93, 2010 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-20185163

RESUMEN

Mechanistic understanding of bioaccumulation in different organisms and environments should take into account the influence of organism and chemical depending factors on the uptake and elimination kinetics of chemicals. Lipophilicity, metabolism, sorption (bioavailability) and biodegradation of chemicals are among the important factors that may significantly affect the bioaccumulation process in soil organisms. This study attempts to model elimination kinetics of organic chemicals in earthworms by accounting for the effects of both chemical and biological properties, including metabolism. The modeling approach that has been developed is based on the concept for simulating metabolism used in the BCF base-line model developed for predicting bioaccumulation in fish. Metabolism was explicitly accounted for by making use of the TIMES engine for simulation of metabolism and a set of principal transformations. Kinetic characteristics of transformations were estimated on the basis of observed kinetics data for the elimination of organic chemicals from earthworms.


Asunto(s)
Modelos Químicos , Oligoquetos/metabolismo , Compuestos Orgánicos/metabolismo , Contaminantes del Suelo/metabolismo , Animales , Cinética , Compuestos Orgánicos/química , Hidrocarburos Policíclicos Aromáticos/química , Hidrocarburos Policíclicos Aromáticos/metabolismo , Contaminantes del Suelo/química
13.
Neuropsychiatr Enfance Adolesc ; 57(3): 221-226, 2009.
Artículo en Francés | MEDLINE | ID: mdl-19655028

RESUMEN

The aim of this paper is to present McHale's coparenting scale,a self-administered questionnaire enabling assessment of the quality of coparenting, and first steps in structural and construct validation of the French version. A total of 41 French speaking Swiss families and 84 US families completed this questionnaire and the Dyadic Adjustment Scale, a measure of marital satisfaction. The results of the Swiss families correspond to those of US families: first, items distributed into four factors (family integrity, conflict, affection and disparagement) and second, a partial link was found between quality of coparenting and marital adjustment. This finding supports the construct validity of the questionnaire, reflecting the established link between these two family sub-systems. Given that coparenting quality has a major influence on children's socio-affective development, the questionnaire will find great use in assessing not just negative features of coparenting, such as conflicts and disparagement, but also positive components such as warmth and support. This will be an important asset for research as well as clinical purposes.

14.
J Electromyogr Kinesiol ; 19(2): 252-8, 2009 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17931886

RESUMEN

The aim of the present study was to test the applicability of indices of muscle fatigue to interference EMG signals detected at various distances from the end-plate region during isometric voluntary contractions at different force levels. Bar electrode with 12 leading off surfaces and 5mm inter-pole distance was used to detect EMG from human m. biceps brachii. The sensitivity of the new spectral indices to detect muscle fatigue was higher than that of mean or median frequencies. Considerable variations in the characteristic frequencies and values of spectral indices that could reflect recruitment and/or rotation of MUs were found under submaximal efforts. The increase of the indices was considered as a sign of peripheral muscle fatigue while their decreasing could be a sign of de-recruitment of fatigued or/and recruitment of new MUs reflecting central fatigue. The sensitivity of the indices to fatigue depended on the electrode arrangement and its longitudinal position in respect of the end-plate region and ends of the muscle fibres. It was larger for the electrodes placed in the middle of the semi-fibre. To overcome the problem with inappropriate position of the electrode, one could use an electrode whose longitudinal dimension would cover the entire semi-length of the analyzed fibres.


Asunto(s)
Algoritmos , Electromiografía/métodos , Contracción Isométrica/fisiología , Fatiga Muscular/fisiología , Músculo Esquelético/fisiología , Resistencia Física/fisiología , Adulto , Brazo/fisiología , Femenino , Humanos , Masculino , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Volición/fisiología
15.
J Electromyogr Kinesiol ; 18(1): 35-43, 2008 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-16963280

RESUMEN

Capabilities of amplitude and spectral methods for information extraction from interference EMG signals were assessed through simulation and preliminary experiment. Muscle was composed of 4 types of motor units (MUs). Different hypotheses on changes in firing frequency of individual MUs, intracellular action potential (IAP) and muscle fibre propagation velocity (MFPV) during fatigue were analyzed. It was found that changes in amplitude characteristics of interference signals (root mean square, RMS, or integrated rectified value, IEMG) detected by intramuscular and surface electrodes differed. RMS and IEMG of surface detected interference signals could increase even under MU firing rate reduction and without MU synchronisation. IAP profile lengthening can affect amplitude characteristics more significantly than MU firing frequency. Thus, an increase of interference EMG amplitude is unreliable to reflect changes in the neural drive. The ratio between EMG amplitude and contraction response can hardly characterise the so-called 'neuromuscular efficiency'. The recently proposed spectral fatigue indices can be used for quantification of interference EMG signals. The indices are practically insensitive to MU firing frequency. IAP profile lengthening and decrease in MFPV enhanced the index value, while recruitment of fast fatigable MUs reduced it. Sensitivity of the indices was higher than that of indices traditionally used.


Asunto(s)
Simulación por Computador/estadística & datos numéricos , Modelos Biológicos , Contracción Muscular/fisiología , Fatiga Muscular/fisiología , Músculo Esquelético/fisiología , Electromiografía/métodos , Electromiografía/estadística & datos numéricos , Humanos , Fibras Musculares Esqueléticas/fisiología , Procesamiento de Señales Asistido por Computador
16.
J Electromyogr Kinesiol ; 18(1): 26-34, 2008 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-16963279

RESUMEN

Decline in amplitude of EMG signals and in the rate of counts of intramuscularly recorded spikes during fatigue is often attributed to a progressive reduction of the neural drive only. As a rule, alterations in intracellular action potential (IAP) are not taken into account. To test correctness of the hypothesis, the effect of various discharge frequency patterns as well as changes in IAP shape and muscle fibre propagation velocity (MFPV) on the spike amplitude-frequency histogram of intramuscular interference EMG signals were simulated and analyzed. It was assumed that muscle was composed of four types of motor units (MUs): slow-twitch fatigue resistant, fast-twitch fatigue resistant, fast intermediate, and fast fatigable. MFPV and IAP duration at initial stage before fatigue as well as their changes differed for individual MU types. Fatigability of individual MU types in normal conditions as well as in the case of ischaemic or low oxygen conditions due to restricted blood flow was also taken into account. It was found that spike amplitude-frequency histogram is poorly sensitive to MU firing frequency, while it is highly sensitive to IAP profile lengthening. It is concluded that spike amplitude-frequency analysis can hardly provide a correct measure of MU rate-coding pattern during fatigue.


Asunto(s)
Simulación por Computador/estadística & datos numéricos , Modelos Biológicos , Contracción Muscular/fisiología , Fatiga Muscular/fisiología , Músculo Esquelético/fisiología , Potenciales de Acción/fisiología , Algoritmos , Electromiografía/métodos , Electromiografía/estadística & datos numéricos , Humanos , Fibras Musculares Esqueléticas/fisiología , Sensibilidad y Especificidad , Factores de Tiempo
17.
Attach Hum Dev ; 9(1): 17-31, 2007 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-17364480

RESUMEN

Role reversal, whereby a child attempts to meet her parent's adult needs for parenting, intimacy, or companionship, has been identified as a risk factor for developmental disturbances. It has been defined from diverse perspectives as a child attachment strategy, a parent - toddler relational disturbance, and a boundary disturbance between parents and child. The recently discovered infant's triangular capacity, namely the sharing of her attention and affects with both parents, allows one to analyse the infant's contribution to early family dynamics. Role reversal was detected in 4 out of 45 father - mother - infant interactions observed in trilogue play from pregnancy to toddlerhood. The developmental trajectories towards role reversal are explored by means of case analyses. Results are compared with cases of problematic triangulation encountered in the same sample. In role reversal, family interactions are rigidly organized around a "two against one" coalition, whereby the normative hierarchy between parents and child is reversed. The child's triangular capacity is overactivated, controlling the tension between her parents by provocation - animation strategies.


Asunto(s)
Relaciones Familiares , Psicología Infantil , Preescolar , Relaciones Padre-Hijo , Femenino , Humanos , Lactante , Masculino , Relaciones Madre-Hijo , Juego e Implementos de Juego/psicología , Embarazo , Teoría Psicológica
18.
SAR QSAR Environ Res ; 17(1): 107-20, 2006 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-16513555

RESUMEN

The role of metabolism in prioritising chemicals according to their potential adverse health effects is extremely important given the fact that innocuous parents can be transformed into toxic metabolites. Our recent efforts in simulating metabolic activation of chemicals are reviewed in this work. The application of metabolic simulators to predict biodegradation (microbial degradation pathways), bioaccumulation (fish liver metabolism), skin sensitisation (skin metabolism), mutagenicity (rat liver S-9 metabolism) are discussed. The ability of OASIS approach to predict metabolism (toxicokinetics) and toxicity (toxicodynamics) of chemicals resulting from their metabolic activation in a single modelling platform is an important advantage of the method. It allows prioritisation of chemicals due to predicted toxicity of their metabolites.


Asunto(s)
Biotransformación , Modelos Estadísticos , Relación Estructura-Actividad Cuantitativa , Animales , Biodegradación Ambiental , Humanos , Pruebas de Mutagenicidad , Ratas , Piel/efectos de los fármacos
19.
J Electromyogr Kinesiol ; 15(4): 341-8, 2005 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-15811604

RESUMEN

The purpose of the present study was to validate the capability of new fatigue indexes (in the time and frequency domain) applied to experimental recordings and thus, to test some assumptions made in previous simulations. The indexes were applied to M-waves detected non-invasively from human m.biceps brachii during repetitive slightly above threshold stimulations. It was found that distance between the motor point and middle of the end-plate region could be relatively large. Under identical conditions (signals detected by monopolar electrodes and high-pass filtered at 1 Hz), the relative changes of the indexes obtained in electrophysiological experiments and simulations were similar. Changes of the intracellular action potential profile during fatigue used in the simulations were consequently supposed to be close to the actual ones for the muscle analyzed. When the high-pass cut-off frequency was higher than 1 Hz, the sensitivity of the index in the time domain was higher, while that in the frequency domain was lower. If the normalizing spectral moment was of higher order, the sensitivity of the spectral index could be even 150-times greater than that of the fatigue indexes traditionally used. Thus, the spectral index promises high capability to assess fatigue during functional electrical stimulation.


Asunto(s)
Diagnóstico por Computador/métodos , Estimulación Eléctrica/métodos , Electromiografía/métodos , Contracción Muscular/fisiología , Fatiga Muscular/fisiología , Músculo Esquelético/fisiología , Resistencia Física/fisiología , Algoritmos , Brazo/fisiología , Humanos , Músculo Esquelético/inervación
20.
J Electromyogr Kinesiol ; 15(3): 290-9, 2005 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-15763676

RESUMEN

Changes in muscle fibre length and surface electrode position with respect to the muscle fibres affect the amplitude and frequency characteristics of surface electromyography (SEMG) in different ways. Knowledge of changes in muscle fibre length would help towards a better interpretation of the signals. The possibility of estimating the length through SEMG during voluntary contractions was checked in this study. The fibres' semi-length was estimated from the product of the conduction velocity and conduction time during which the wave of excitation propagated from the end-plate region to the ends of the fibres. Short (10 s), moderate (30% of maximum voluntary contraction) isometric contractions were performed by 10 subjects at different elbow joint angles (80-140 degrees in steps of 20 degrees ). Monopolar signals were detected non-invasively, using a two-dimensional electrode array. High spatial resolution EMG and a decomposition technique were utilised to extract single motor unit activities for triggered averaging and to estimate conduction velocity. A significant increase with joint angle was found in conduction time and estimated fibre semi-length. Changes in conduction velocity with joint angle were found to be not significant. The methodology described allows the relative changes in fibres' semi-length to be estimated from SEMG data.


Asunto(s)
Potenciales de Acción/fisiología , Articulación del Codo/anatomía & histología , Neuronas Motoras/fisiología , Fibras Musculares Esqueléticas/fisiología , Adulto , Articulación del Codo/fisiología , Electromiografía/métodos , Femenino , Humanos , Contracción Isométrica/fisiología , Masculino , Modelos Biológicos , Modelos Neurológicos , Placa Motora/fisiología , Fibras Musculares Esqueléticas/ultraestructura , Músculo Esquelético/inervación , Músculo Esquelético/fisiología , Conducción Nerviosa/fisiología , Rango del Movimiento Articular/fisiología , Procesamiento de Señales Asistido por Computador , Factores de Tiempo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA