RESUMEN
ABSTRACT The purpose of this study was to highlight the impact of biomechanical corneal response in available in vivo tonometry methods for glaucoma management. Systematic review of non-contact air-puff tonometers that analyzes the corneal deformation response, with special focus on the investigation of the correlation of derived parameters with intraocular pressure measurements. The two actual and commercially available in vivo corneal tonometers provide promising information about biomechanical characteristics of the cornea and its relation to glaucoma, allowing the development of new protocols to evaluate, diagnose, and manage this disease.
RESUMO O objetivo deste estudo é destacar o impacto da resposta biomecânica corneana em métodos de tonometria in vivo disponíveis para o manejo do glaucoma. Trata-se de revisão sistemática de tonômetros de ar que analisa a resposta à deformação corneana, com foco especial na investigação da correlação dos parâmetros derivados com as medições da pressão intraocular. Os dois tonômetros mais recentes e comercialmente disponíveis fornecem informações promissoras sobre as características biomecânicas da córnea e sua relação com o glaucoma, permitindo o desenvolvimento de novos protocolos para avaliar, diagnosticar e controlar a doença.
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Humanos , Tonometría Ocular/instrumentación , Tonometría Ocular/métodos , Fenómenos Biomecánicos , Córnea/anatomía & histología , Córnea/fisiología , Presión Intraocular/fisiología , Glaucoma/fisiopatología , Hipertensión Ocular/fisiopatología , Técnicas de Diagnóstico Oftalmológico/instrumentación , Elasticidad/fisiología , Modelos TeóricosRESUMEN
The successful assembly of a closed protein shell (or capsid) is a key step in the replication of viruses and in the production of artificial viral cages for bio/nanotechnological applications. During self-assembly, the favorable binding energy competes with the energetic cost of the growing edge and the elastic stresses generated due to the curvature of the capsid. As a result, incomplete structures such as open caps, cylindrical or ribbon-shaped shells may emerge, preventing the successful replication of viruses. Using elasticity theory and coarse-grained simulations, we analyze the conditions required for these processes to occur and their significance for empty virus self-assembly. We find that the outcome of the assembly can be recast into a universal phase diagram showing that viruses with high mechanical resistance cannot be self-assembled directly as spherical structures. The results of our study justify the need of a maturation step and suggest promising routes to hinder viral infections by inducing mis-assembly.
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Proteínas de la Cápside/metabolismo , Cápside/metabolismo , Simulación por Computador , Elasticidad/fisiología , Ensamble de Virus/fisiologíaRESUMEN
BACKGROUND: All over the world, people face the same skin problems. However, their skin characteristics are different. Thus, it is a challenge to prescribe treatments that will be effective on different skin types. Therefore, it is very important to consider the skin biology when indicating a dermocosmetic treatment. OBJECTIVES: To assess skin biophysical parameters in French and Brazilian subjects and to verify the efficacy of four dermocosmetic treatments in these populations. METHODS: Five test areas were defined on each volar forearm of the eighteen Brazilian and eighteen French participants using a randomized design. Biophysical measurements in terms of skin hydration, skin barrier function, skin brightness, and skin viscoelasticity were performed before and after 60 minutes of treatment. RESULTS: Skin biophysical differences between populations were found. French skin has been shown to be more hydrated regarding epidermal mechanic properties and stratum corneum water content and more radiant when compared with Brazilian skin. However, it showed more signs of cutaneous aging and fatigue effects on skin. The Brazilian skin showed better skin barrier function. In addition, the treatments were effective in both populations. CONCLUSIONS: Despite the differences found in French and Brazilian skin, the proposed dermocosmetic treatments showed effective in both populations.
Asunto(s)
Blanqueadores/administración & dosificación , Técnicas Cosméticas , Envejecimiento de la Piel/efectos de los fármacos , Crema para la Piel/administración & dosificación , Piel/efectos de los fármacos , Adulto , Brasil , Elasticidad/efectos de los fármacos , Elasticidad/fisiología , Francia , Geografía , Humanos , Piel/química , Envejecimiento de la Piel/fisiología , Resultado del Tratamiento , Viscosidad/efectos de los fármacos , Pérdida Insensible de Agua/efectos de los fármacos , Pérdida Insensible de Agua/fisiología , Adulto JovenRESUMEN
OBJECTIVE: Skin biomechanics are physical properties that protect the body from injury. Little is known about differences in skin biomechanics in racial/ethnic groups and the role of skin color in these differences. The purpose of this study was to determine the relationship between skin biomechanics (viscoelasticity, hydration) and skin color, when controlling for demographic and health-related variables in a sample of Puerto Rican and non-Puerto Rican women. METHODS: We performed a secondary analysis of data from 545 women in a longitudinal, observational study of skin injury in Puerto Rico and the United States. Data included measures of skin viscoelasticity, skin hydration, skin color, demographic, and health related variables. Skin color was measured by spectrophotometry (L* - lightness/darkness, a*- redness/greenness, b* - yellowness/blueness). The sample was 12.5% Puerto Rican, 27.3% non-Puerto Rican Latina, 28.8% Black, 28.6% White, and 2.8% Other. RESULTS: Regression analyses showed that: 1) higher levels of skin viscoelasticity were associated with lower age, higher BMI, and identifying as non-Puerto Rican Latina as compared to Puerto Rican; (all p < .001); and 2) higher levels of hydration were associated with lower L* values, higher health status, lower BMI, and identifying as non-Puerto Rican Latina, White, or Other as compared to Puerto Rican (all p < .05). CONCLUSION: When adjusting for skin color, Puerto Rican women had lower viscoelasticity and hydration as compared to other groups. Puerto Rican women may be at long-term risk for skin alterations, including pressure injury, as they age or become chronically ill.
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Elasticidad/fisiología , Fenómenos Fisiológicos de la Piel , Pigmentación de la Piel/fisiología , Adulto , Negro o Afroamericano , Factores de Edad , Fenómenos Biomecánicos , Índice de Masa Corporal , Femenino , Hispánicos o Latinos , Humanos , Estudios Longitudinales , Persona de Mediana Edad , Puerto Rico , Estados Unidos , Población Blanca , Adulto JovenRESUMEN
Gestational exposure to air pollution is associated with negative outcomes in newborns and children. In a previous study, we demonstrated a synergistic negative effect of pre- and postnatal exposure to PM2.5 on lung development in mice. However, the means by which air pollution affects development of the lung have not yet been identified. In this study, we exposed pregnant BALB/c mice and their offspring to concentrated urban PM2.5 (from São Paulo, Brazil; target dose 600⯵g/m3 for 1â¯h daily). Exposure was started on embryonic day 5.5 (E5.5, time of placental implantation). Lung tissue of fetuses and offspring was submitted to stereological and transcriptomic analyses at E14.5 (pseudoglandular stage of lung development), E18.5 (saccular stage) and P40 (postnatal day 40, alveolarized lung). Additionally, lung function and cellularity of bronchoalveolar lavage (BAL) fluid were studied in offspring animals at P40. Compared to control animals that were exposed to filtered air throughout gestation and postnatal life, PM-exposed mice exhibited higher lung elastance and a lower alveolar number at P40 whilst the total lung volume and cellularity of BAL fluid were not affected. Glandular and saccular structures of fetal lungs were not altered upon gestational exposure; transcriptomic signatures, however, showed changes related to DNA damage and its regulation, inflammation and regulation of cell proliferation. A differential expression was validated at E14.5 for the candidates Sox8, Angptl4 and Gas1. Our data substantiate the in utero biomolecular effect of gestational exposure to air pollution and provide first-time stereological evidence that pre- and early life-postnatal exposure compromise lung development, leading to a reduced number of alveoli and an impairment of lung function in the adult mouse.
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Contaminación del Aire/efectos adversos , Pulmón/fisiopatología , Material Particulado/efectos adversos , Material Particulado/análisis , Alveolos Pulmonares/patología , Proteína 4 Similar a la Angiopoyetina/biosíntesis , Animales , Brasil , Proteínas de Ciclo Celular/biosíntesis , Daño del ADN/efectos de los fármacos , Elasticidad/fisiología , Femenino , Proteínas Ligadas a GPI/biosíntesis , Regulación de la Expresión Génica/efectos de los fármacos , Pulmón/crecimiento & desarrollo , Pulmón/metabolismo , Pulmón/patología , Masculino , Ratones , Embarazo , Efectos Tardíos de la Exposición Prenatal/metabolismo , Efectos Tardíos de la Exposición Prenatal/fisiopatología , Factores de Transcripción SOXE/biosíntesis , Factores de TiempoRESUMEN
PURPOSE: We compared respiratory mechanics between the positive end-expiratory pressure of minimal respiratory system elastance (PEEPminErs) and three levels of PEEP during low-tidal-volume (6 mL/kg) ventilation in rats. METHODS: Twenty-four rats were anesthetized, paralyzed, and mechanically ventilated. Airway pressure (Paw), flow (F), and volume (V) were fitted by a linear single compartment model (LSCM) Paw(t) = Ers × V(t) + Rrs × F(t) + PEEP or a volume- and flow-dependent SCM (VFDSCM) Paw(t) = (E1 + E2 × V(t)) × V(t) + (K1 + K2 × |F(t)|) × F(t) + PEEP, where Ers and Rrs are respiratory system elastance and resistance, respectively; E1 and E2× V are volume-independent and volume-dependent Ers, respectively; and K1 and K2 × F are flow-independent and flow-dependent Rrs, respectively. Animals were ventilated for 1 h at PEEP 0 cmH2O (ZEEP); PEEPminErs; 2 cmH2O above PEEPminErs (PEEPminErs+2); or 4 cmH2O above PEEPminErs (PEEPminErs+4). Alveolar tidal recruitment/derecruitment and overdistension were assessed by the index %E2 = 100 × [(E2 × VT)/(E1 + |E2| × VT)], and alveolar stability by the slope of Ers(t). RESULTS: %E2 varied between 0 and 30% at PEEPminErs in most respiratory cycles. Alveolar Tidal recruitment/derecruitment (%E2 < 0) and overdistension (%E2 > 30) were predominant in the absence of PEEP and in PEEP levels higher than PEEPminErs, respectively. The slope of Ers(t) was different from zero in all groups besides PEEPminErs+4. CONCLUSIONS: PEEPminErs presented the best compromise between alveolar tidal recruitment/derecruitment and overdistension, during 1 h of low-VT mechanical ventilation.
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Elasticidad/fisiología , Pulmón/fisiología , Respiración con Presión Positiva/métodos , Mecánica Respiratoria/fisiología , Anestesia , Animales , Ratas , Respiración Artificial/métodos , Volumen de Ventilación PulmonarRESUMEN
Measuring corneal biomechanical properties is still challenging. There are several clinical applications for biomechanical measurements, including the detection of mild or early forms of ectatic corneal diseases. This article reviews clinical applications for biomechanical measurements provided by the Corvis ST dynamic non contact tonometer.
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Córnea/fisiopatología , Elasticidad/fisiología , Queratocono/fisiopatología , Fenómenos Biomecánicos , Humanos , Presión Intraocular/fisiología , Tonometría OcularRESUMEN
Abstract Purpose: To evaluate the effect of transforming growth factor β1 (TGF-β1) on tendon-to-bone reconstruction of rotator cuff tears. Methods: Seventy-two rat supraspinatus tendons were transected and reconstructed in situ. At 8 and 16 weeks, specimens of three groups; that is control, L-dose (low dose), and H-dose (high dose) were harvested and underwent a biomechanical test to evaluate the maximum load and stiffness values. Histology sections of the tendon-to-bone interface were identified by hematoxylin-eosin or Masson trichrome stain. Collagen type III was observed by picric acid sirius red staining under polarized light. The level of insulin-like growth factor 1 (IGF-1) and vascular endothelial growth factor (VEGF) was measured by the enzyme-linked immunosorbent assay (ELISA) method. Results: Collagen type III of the H-dose group had a significant difference in histology structure compared with the L-dose group (P<0.05). The maximum load and stiffness decreased significantly in the control group compared with the values of the L-dose and H-dose groups. The stiffness among the three groups differed significantly at the same postoperative time (P<0.05). Interestingly, progressive reestablishment of collagen type III affected tendon-to-bone healing significantly in the later stages. Conclusion: The H-dose was associated with an increased collagen type III morphology stimulated by TGF-β1.
Asunto(s)
Animales , Masculino , Ratas , Traumatismos de los Tendones/tratamiento farmacológico , Cicatrización de Heridas/fisiología , Manguito de los Rotadores/cirugía , Factores de Crecimiento Endotelial Vascular/metabolismo , Factor de Crecimiento Transformador beta1/metabolismo , Lesiones del Manguito de los Rotadores/cirugía , Traumatismos de los Tendones/metabolismo , Resistencia a la Tracción/fisiología , Cicatrización de Heridas/efectos de los fármacos , Fenómenos Biomecánicos , Ensayo de Inmunoadsorción Enzimática , Manguito de los Rotadores/metabolismo , Ratas Sprague-Dawley , Colágeno Tipo III/metabolismo , Modelos Animales de Enfermedad , Elasticidad/fisiología , Factor de Crecimiento Transformador beta1/farmacología , Fuerza Muscular/fisiología , Fibroblastos/efectos de los fármacos , Fibroblastos/fisiología , Lesiones del Manguito de los Rotadores/metabolismoRESUMEN
Cardiovascular risk is increased in HIV-infected patients and has become a leading cause of morbi-mortality in this population. The purpose of this study is to compare HIV-infected patients on antiretroviral therapy (ART) and ART-naïve HIV-infected patients regarding arterial elasticity. From September 2010 to September 2015, 105 HIV-infected subjects were enrolled, 41 ART-naïve and 64 on ART with stable viral suppression. Elasticity of large and small arteries (LAE and SAE) was assessed by analysis of radial pulse waveforms using a calibrated device. A single set of measurements was performed. Multivariate linear regression models were constructed to estimate independent correlates of arterial elasticity. On-ART and ART-naïve patients were similar with respect to gender, age, body mass index, Framingham cardiovascular risk score, smoking habits, and CD4+ counts. Median time on treatment was 60 months and 79% of patients were on regimens based on non-nucleoside reverse-transcriptase inhibitors. No significant differences in LAE and SAE assessments were found between groups. However, time on ART and cholesterol levels were independently associated with LAE impairment. No association between arterial elasticity and CD4+ counts was found. We conclude that cumulative exposure to ART may play a role on LAE impairment and deserves further investigation.
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Fármacos Anti-VIH/uso terapéutico , Arterias/fisiopatología , Elasticidad/fisiología , Infecciones por VIH/fisiopatología , Resistencia Vascular/fisiología , Adulto , Terapia Antirretroviral Altamente Activa , Estudios Transversales , Femenino , Infecciones por VIH/tratamiento farmacológico , Humanos , MasculinoRESUMEN
Cardiovascular risk is increased in HIV-infected patients and has become a leading cause of morbimortality in this population. The purpose of this study is to compare HIV-infected patients on antiretroviral therapy (ART) and ART-naïve HIV-infected patients regarding arterial elasticity. From September 2010 to September 2015, 105 HIV-infected subjects were enrolled, 41 ART-naïve and 64 on ART with stable viral suppression. Elasticity of large and small arteries (LAE and SAE) was assessed by analysis of radial pulse waveforms using a calibrated device. A single set of measurements was performed. Multivariate linear regression models were constructed to estimate independent correlates of arterial elasticity. On-ART and ART-naïve patients were similar with respect to gender, age, body mass index, Framingham cardiovascular risk score, smoking habits, and CD4+ counts. Median time on treatment was 60 months and 79% of patients were on regimens based on non-nucleoside reverse-transcriptase inhibitors. No significant differences in LAE and SAE assessments were found between groups. However, time on ART and cholesterol levels were independently associated with LAE impairment. No association between arterial elasticity and CD4+ counts was found. We conclude that cumulative exposure to ART may play a role on LAE impairment and deserves further investigation.
El riesgo cardiovascular está incrementado en los pacientes HIV seropositivos y se ha convertido en una de las principales causas de morbimortalidad en esta población. El objetivo de este estudio fue comparar la elasticidad de grandes y pequeñas arterias (LAE y SAE) en pacientes infectados por HIV con y sin terapia antirretroviral. De septiembre de 2010 a septiembre de 2015 se enrolaron 105 pacientes con infección por HIV, 41 vírgenes de antirretrovirales y 64 con tratamiento estable en supresión viral. LAE y SAE fueron evaluados mediante análisis de la onda de pulso radial. Se construyeron modelos de regresión lineal múltiple para evaluar los predictores independientes de la elasticidad arterial. Los grupos en tratamiento y naïve fueron similares con respecto al sexo, edad, índice de masa corporal, índice de Framingham, tabaquismo y recuento de CD4+. La mediana de tiempo en tratamiento antirretroviral fue 60 meses y el 79% de los pacientes recibieron inhibidores no nucleosídicos. No hubo diferencias significativas entre los grupos en los valores de LAE y SAE. Sin embargo, el tiempo en tratamiento y el nivel de colesterol plasmático se asociaron independientemente con deterioro de LAE. No observamos asociaciones entre la elasticidad arterial y los recuentos de CD4+. Concluimos que la exposición acumulada al tratamiento antirretroviral podría contribuir al deterioro de la LAE. Este hallazgo merece ulterior investigación.
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Humanos , Masculino , Femenino , Adulto , Arterias/fisiopatología , Resistencia Vascular/fisiología , Infecciones por VIH/fisiopatología , Fármacos Anti-VIH/uso terapéutico , Elasticidad/fisiología , Infecciones por VIH/tratamiento farmacológico , Estudios Transversales , Terapia Antirretroviral Altamente ActivaRESUMEN
Abstract Cardiovascular diseases (CVD) account annually for almost one third of all deaths worldwide. Among the CVD, systemic arterial hypertension (SAH) is related to more than half of those outcomes. Type 2 diabetes mellitus is an independent risk factor for SAH because it causes functional and structural damage to the arterial wall, leading to stiffness. Several studies have related oxidative stress, production of free radicals, and neuroendocrine and genetic changes to the physiopathogenesis of vascular aging. Indirect ways to analyze that aging process have been widely studied, pulse wave velocity (PWV) being considered gold standard to assess arterial stiffness, because there is large epidemiological evidence of its predictive value for cardiovascular events, and it requires little technical knowledge to be performed. A pulse wave is generated during each cardiac contraction and travels along the arterial bed until finding peripheral resistance or any bifurcation point, determining the appearance of a reflected wave. In young individuals, arteries tend to be more elastic, therefore, the reflected wave occurs later in the cardiac cycle, reaching the heart during diastole. In older individuals, however, the reflected wave occurs earlier, reaching the heart during systole. Because PWV is an important biomarker of vascular damage, highly valuable in determining the patient's global cardiovascular risk, we chose to review the articles on vascular aging in the context of cardiovascular risk factors and the tools available to the early identification of that damage.
Resumo As doenças cardiovasculares são anualmente responsáveis por quase um terço do total de mortes no mundo. Dentre elas, a hipertensão arterial sistêmica (HAS) está relacionada com mais da metade desses desfechos. O diabetes mellitus tipo 2 é visto com um fator de risco independente para HAS por causar lesões funcionais e estruturais na parede arterial, ocasionando-lhe enrijecimento. Diversos estudos relacionam o stress oxidativo, a produção de radicais livres, as alterações neuroendócrinas e genéticas com a fisiopatogenia do envelhecimento vascular. Formas indiretas para analisar esse processo de envelhecimento têm sido amplamente estudadas, dentre elas, a velocidade de onda de pulso (VOP) é vista como o padrão-ouro para avaliar a rigidez arterial por existir maior número de evidências epidemiológicas do seu valor preditivo para eventos cardiovasculares além de requerer pouco conhecimento técnico para sua realização. A onda de pulso é gerada durante cada contração cardíaca e percorre o leito arterial até encontrar resistência periférica ou algum ponto de bifurcação, ocasionando o surgimento de uma onda refletida. Em indivíduos jovens, as artérias tendem a ser mais elásticas, em consequência, a onda é refletida mais tardiamente no ciclo cardíaco e atinge o coração no momento da diástole, enquanto nos mais velhos, com reflexão mais precoce da onda, tende a acontecer na sístole. Por ser a VOP um importante biomarcador de dano vascular, de grande valia para a determinação do risco global cardiovascular do paciente, optamos por revisar os artigos referentes ao envelhecimento vascular no contexto dos fatores de risco cardiovasculares e as ferramentas disponíveis para a identificação precoce desse dano.
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Humanos , Flujo Pulsátil/fisiología , Envejecimiento/fisiología , Elasticidad/fisiología , Rigidez Vascular/fisiologíaRESUMEN
Cardiovascular diseases (CVD) account annually for almost one third of all deaths worldwide. Among the CVD, systemic arterial hypertension (SAH) is related to more than half of those outcomes. Type 2 diabetes mellitus is an independent risk factor for SAH because it causes functional and structural damage to the arterial wall, leading to stiffness. Several studies have related oxidative stress, production of free radicals, and neuroendocrine and genetic changes to the physiopathogenesis of vascular aging. Indirect ways to analyze that aging process have been widely studied, pulse wave velocity (PWV) being considered gold standard to assess arterial stiffness, because there is large epidemiological evidence of its predictive value for cardiovascular events, and it requires little technical knowledge to be performed. A pulse wave is generated during each cardiac contraction and travels along the arterial bed until finding peripheral resistance or any bifurcation point, determining the appearance of a reflected wave. In young individuals, arteries tend to be more elastic, therefore, the reflected wave occurs later in the cardiac cycle, reaching the heart during diastole. In older individuals, however, the reflected wave occurs earlier, reaching the heart during systole. Because PWV is an important biomarker of vascular damage, highly valuable in determining the patient's global cardiovascular risk, we chose to review the articles on vascular aging in the context of cardiovascular risk factors and the tools available to the early identification of that damage.
Asunto(s)
Envejecimiento/fisiología , Elasticidad/fisiología , Flujo Pulsátil/fisiología , Rigidez Vascular/fisiología , HumanosRESUMEN
PURPOSE: To evaluate the effect of transforming growth factor ß1 (TGF-ß1) on tendon-to-bone reconstruction of rotator cuff tears. METHODS: Seventy-two rat supraspinatus tendons were transected and reconstructed in situ. At 8 and 16 weeks, specimens of three groups; that is control, L-dose (low dose), and H-dose (high dose) were harvested and underwent a biomechanical test to evaluate the maximum load and stiffness values. Histology sections of the tendon-to-bone interface were identified by hematoxylin-eosin or Masson trichrome stain. Collagen type III was observed by picric acid sirius red staining under polarized light. The level of insulin-like growth factor 1 (IGF-1) and vascular endothelial growth factor (VEGF) was measured by the enzyme-linked immunosorbent assay (ELISA) method. RESULTS: Collagen type III of the H-dose group had a significant difference in histology structure compared with the L-dose group (P<0.05). The maximum load and stiffness decreased significantly in the control group compared with the values of the L-dose and H-dose groups. The stiffness among the three groups differed significantly at the same postoperative time (P<0.05). Interestingly, progressive reestablishment of collagen type III affected tendon-to-bone healing significantly in the later stages. CONCLUSION: The H-dose was associated with an increased collagen type III morphology stimulated by TGF-ß1.
Asunto(s)
Lesiones del Manguito de los Rotadores/cirugía , Manguito de los Rotadores/cirugía , Traumatismos de los Tendones/tratamiento farmacológico , Factor de Crecimiento Transformador beta1/metabolismo , Factores de Crecimiento Endotelial Vascular/metabolismo , Cicatrización de Heridas/fisiología , Animales , Fenómenos Biomecánicos , Colágeno Tipo III/metabolismo , Modelos Animales de Enfermedad , Elasticidad/fisiología , Ensayo de Inmunoadsorción Enzimática , Fibroblastos/efectos de los fármacos , Fibroblastos/fisiología , Masculino , Fuerza Muscular/fisiología , Ratas , Ratas Sprague-Dawley , Manguito de los Rotadores/metabolismo , Lesiones del Manguito de los Rotadores/metabolismo , Traumatismos de los Tendones/metabolismo , Resistencia a la Tracción/fisiología , Factor de Crecimiento Transformador beta1/farmacología , Cicatrización de Heridas/efectos de los fármacosRESUMEN
BACKGROUND: Knowledge of skin biology and its alterations in different populations is very important for the development of appropriate skincare strategies. OBJECTIVES: To evaluate and compare morphological, structural and biophysical properties of photoaged skin in French and Brazilian populations, using biophysical and skin-imaging techniques. METHODS: Forty-one French and 41 Brazilian healthy, female volunteers aged between 40 and 65 years were enrolled. Each participant completed a questionnaire concerning habits related to cosmetic use, sun exposure and sun protection during different life periods. Skin on the face and volar forearm was evaluated using noninvasive techniques, to determine skin colour, transepidermal water loss (TEWL), stratum corneum water content, skin microrelief, skin viscoelasticity and dermis structure. Reflectance confocal microscopy was used to measure epidermal layer thickness and epidermal morphological and structural characteristics. RESULTS: Compared with Brazilian skin, French skin was more hydrated, had a lower TEWL and presented a distinct viscoelastic profile on the forearms and face. Brazilian facial skin was more wrinkled, and the dermis was less echogenic on the forearms and face. The French participants had thicker stratum corneum. Brazilian facial skin presented a higher prevalence of rete ridge effacement, low interkeratinocyte reflectance, huddled collagen and solar elastosis. CONCLUSIONS: Morphological, structural and biophysical differences were found when assessing the skin of the Brazilian and French participants, who were exposed to different environmental factors.
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Envejecimiento de la Piel/patología , Adulto , Anciano , Agua Corporal , Brasil/etnología , Elasticidad/fisiología , Epidermis/fisiología , Cara , Femenino , Antebrazo , Francia/etnología , Humanos , Persona de Mediana Edad , Satisfacción Personal , Envejecimiento de la Piel/etnología , Envejecimiento de la Piel/fisiología , Luz Solar , Protectores Solares/uso terapéuticoRESUMEN
Different authors have modelled myofascial tissue connectivity over a distance using cadaveric models, but in vivo models are scarce. The aim of this study was to evaluate the relationship between pelvic motion and deep fascia displacement in the medial gastrocnemius (MG). Deep fascia displacement of the MG was evaluated through automatic tracking with an ultrasound. Angular variation of the pelvis was determined by 2D kinematic analysis. The average maximum fascia displacement and pelvic motion were 1.501â ±â 0.78â mm and 6.55â ±â 2.47â °, respectively. The result of a simple linear regression between fascia displacement and pelvic motion for three task executions by 17 individuals was râ =â 0.791 (Pâ <â 0.001). Moreover, hamstring flexibility was related to a lower anterior tilt of the pelvis (râ =â 0.544, Pâ <â 0.024) and a lower deep fascia displacement of the MG (râ =â 0.449, Pâ <â 0.042). These results support the concept of myofascial tissue connectivity over a distance in an in vivo model, reinforce the functional concept of force transmission through synergistic muscle groups, and grant new perspectives for the role of fasciae in restricting movement in remote zones.
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Fascia , Movimiento/fisiología , Músculo Esquelético , Pelvis , Rango del Movimiento Articular/fisiología , Adulto , Fenómenos Biomecánicos , Elasticidad/fisiología , Fascia/anatomía & histología , Fascia/diagnóstico por imagen , Fascia/fisiología , Humanos , Masculino , Músculo Esquelético/anatomía & histología , Músculo Esquelético/diagnóstico por imagen , Pelvis/anatomía & histología , Pelvis/diagnóstico por imagen , Pelvis/fisiología , Análisis de Regresión , Ultrasonografía , Soporte de Peso/fisiología , Adulto JovenRESUMEN
INTRODUCTION: We investigated the viscoelastic stress relaxation response before and after a 10-week hamstrings static stretch program. METHODS: The maximal range of motion (ROMmax ) and maximal torque (Torquemax ) were assessed before and after a 10-week stretching program. Six 30-s static stretches at a predetermined torque were performed, and the relative change in stress relaxation was examined. RESULTS: ROMmax and Torquemax increased by 53% and 82%, respectively (P < 0.001). The relative stress relaxation (RSR) decreased significantly for repetition 1 when comparing the pretest (25%) and posttest (21%) values (P = 0.003). A significant decrease was also observed for repetitions 2 and 3 (P < 0.014), with no significant difference in repetitions 4-6 (P > 0.056). CONCLUSIONS: Individuals who participated in a 10-week hamstrings passive-static stretch program had a reduced RSR response. A higher stretch intensity or longer duration may be necessary to achieve RSRs similar to those reported before the stretch program.
Asunto(s)
Elasticidad/fisiología , Relajación Muscular/fisiología , Ejercicios de Estiramiento Muscular/métodos , Músculo Esquelético/fisiología , Estrés Fisiológico/fisiología , Humanos , Masculino , Rango del Movimiento Articular/fisiología , Tendones/fisiología , Torque , Resultado del Tratamiento , Adulto JovenRESUMEN
BACKGROUND: Autologous flexor tendons are widely used for anterior cruciate ligament (ACL) reconstruction. Pretension of the graft before fixation has been described as part of the surgical technique, nevertheless there is no consensus on the type and amount to tension needed to increase the stiffness without affecting its biomechanical properties.Our hypothesis is cyclic tension increases flexor tendon stiffness without affecting its ultimate failure at maximum loads (UFML). METHODS: Forty-five flexor digitorum profundus tendons harvested from domestic pigs (Sus scrofa domestica) were randomly divided into three groups: E1 (n=15), E2 (n=15) and C (n=15). Groups E1 and E2 were subjected to 50 cyclic loads at a 1 Hz frequency, at 70N and 100N respectively, group C was not intervened. The three groups were then tested for UFML. Cyclic loads and measurements were performed using a Stress-Strain machine (SST 1.0 Kinetecnic). Results were analyzed using GrapgPad statistical software. Groups were compared using Mann-Whitney test with a 95% confidence interval. RESULTS: Significant increased stiffness for group E1 (p=0.02) and group E2 ( p<0.01) when compared to group C. The stiffness of group E2 was also significantly higher than E1 (p=0.03). There was a significant reduction on the UFML between group E2 and C (p<0.01), which was not observed when comparing groups E1 and C. CONCLUSION: Cyclic loads at 70N result in an increased stiffness of flexor tendons without affecting its ultimate failure at maximum loads. Cyclic loads at higher tensions might cause a deleterious effect on the biomechanical properties of flexor tendon grafts.
Asunto(s)
Reconstrucción del Ligamento Cruzado Anterior/métodos , Ligamento Cruzado Anterior/cirugía , Elasticidad/fisiología , Tendones/fisiología , Animales , Fenómenos Biomecánicos , Sus scrofa , Porcinos , Tendones/trasplanteRESUMEN
Age and growth analysis is essential to fisheries management. Indirect methods to calculate growth are widely used; however, length frequency data analysis in sea cucumbers is complicated by high data variability caused by body wall elasticity. Here we calculated Isostichopus badionotus parameters of the von Bertalanffy growth function. In order to address bias produced by body wall elasticity, we compared the performance of four measurements and one compound index that combines different biometric parameters: the square root of the length-width product (SLW). Results showed that variability in length data due to body wall elasticity was controlled by using body length (Le) from the SLW compound index. Growth in I. badionotus follows a negative allometric tendency. Slow or zero growth periods were observed during October and November, when weather conditions were adverse.
Asunto(s)
Pepinos de Mar/crecimiento & desarrollo , Pepinos de Mar/fisiología , Animales , Elasticidad/fisiología , Explotaciones PesquerasRESUMEN
Studies suggest that standard corneal collagen crosslinking (CXL) is a safe and effective treatment to stiffen the cornea for keratoconus and other ectatic corneal disorders. The purpose of the present study was to compare the biomechanical effects of transepithelial benzalkonium chloride-EDTA (BAC-EDTA) riboflavin-UVA crosslinking to standard epithelium-off riboflavin-UVA crosslinking in a rabbit model. Corneal stiffness was quantified using optical coherence elastography at two months after treatment. The mean lateral-to-axial displacement ratio for the BAC-EDTA transepithelial CXL group was lower (greater stiffness) [0.062 ± 0.042, mean ± SD] than epithelium-off CXL (mean ± SD: 0.065 ± 0.045) or untreated control eyes (0.069 ± 0.044). Using ANOVA with Tukey correction, a statistically significant difference was found between the BAC-EDTA transepithelial CXL group and standard epithelium-off CXL (p = 0.0019) or the untreated control (p < 0.0001) groups. A graph of the probability density functions for biomechanical stiffness also showed a greater shift in stiffening in the BAC-EDTA transepithelial CXL group than the standard epithelium-off CXL or untreated control group. These results demonstrated that the biomechanical stiffening effect produced by BAC-EDTA transepithelial CXL was greater than that produced by standard epithelium-off CXL in a rabbit model.
Asunto(s)
Córnea/efectos de los fármacos , Reactivos de Enlaces Cruzados/farmacología , Elasticidad/efectos de los fármacos , Fármacos Fotosensibilizantes/farmacología , Riboflavina/farmacología , Análisis de Varianza , Animales , Compuestos de Benzalconio/farmacología , Fenómenos Biomecánicos/fisiología , Quelantes/farmacología , Córnea/fisiopatología , Elasticidad/fisiología , Diagnóstico por Imagen de Elasticidad , Modelos Animales , Conejos , Rayos UltravioletaRESUMEN
PURPOSE: To evaluate ocular biomechanical metrics given by the CorVis ST (Oculus, Inc., Berlin, Germany) in a population of healthy Brazilian patients. METHODS: An observational and cross-sectional study involving 1 eye randomly selected from 90 healthy patients. Studied parameters (including deformation amplitude, first applanation time, highest concavity time, second applanation time, first applanation length, second applanation length, curvature radius highest concavity, curvature radius normal, velocity in, and velocity out) derived from the CorVis ST were correlated to central corneal thickness from the Pentacam (Oculus, Inc.). Differences between data on the basis of gender were evaluated. RESULTS: Mean patient age was 35.80 ± 12.83 years (range: 21.07 to 78.84 years). Mean central corneal thickness was 547.50 ± 32.00 µm (range: 490 to 647 µm) and mean spherical equivalent refraction was -3.29 ± 3.69 diopters (range: -9.50 to +10.37 diopters). Mean deformation amplitude was 1.05 ± 0.08 mm (range: 0.91 to 1.26 mm). Highest concavity time was 18.38 ± 0.93 ms (range: 16.95 to 21.07 ms). Intraocular pressure was 16.43 ± 2.15 mm Hg (range: 11.50 to 21.0 mm Hg). First applanation time was 8.32 ± 0.33 ms (range: 7.53 to 9.12 ms) and second applanation time was 23.80 ± 0.44 ms (range: 22.76 to 24.95 ms). First applanation length (max) was 2.07 ± 0.38 mm (range: 1.20 to 3.10 mm) and second applanation length (max) was 2.37 ± 0.47 mm (range: 1.33 to 4.12 mm). Curvature radius highest concavity was 11.09 ± 2.06 mm (range: 7.58 to 15.98 mm) and curvature radius normal was 7.59 ± 0.67 mm (range: 6.82 to 11.02 mm). Velocity in was 0.21 ± 0.05 m/s (range: 0.16 to 0.72 m/s) and velocity out was -0.33 ± 0.07 m/s (range: -0.72 to -0.20 m/s). Studied parameters were not associated with gender. CONCLUSIONS: Eight of 11 ocular biomechanical metrics given by the CorVis ST were associated with central corneal thickness, but the influence of central corneal thickness on these measurements was low.