Characteristics of brain injury induced by shock wave propagation in solids after explosion in rats explosion in rats / 解放军医学杂志

Objective To observe the characteristics of rat brain injury induced by shock wave propagation in solids resulting from underwater explosion and explore the related mechanism. Methods Explosion source outside the simulated ship cabin underwater was detonated for establishing a model of brain injury in rats by shock wave propagation in solid; 72 male SD rats were randomly divided into normal control group (n=8), injury group 1 (600mg RDX paper particle explosion source, n=32), injury group 2 (800mg RDX paper particle explosion source, n=32). The each injury group was randomly divided into 4 subgroups (n=8), 3, 6, 24 and 72h groups. The division plate as a whole and the head of 8 rats in each injury group were measured for the peak value of the solid shock wave, its rising time and the duration time of shock wave propagation in solid. To observe the physiological changes of animals after injury, plasma samples were collected for determination of brain damage markers, NSE and S-100 β. All the animals were sacrificed, the right hemisphere of the brain was taken in each group of animals, weighting after baking, and the brain water content was calculated. Pathological examination was performed for left cerebral hemisphere in 24-h group. The normal pyramidal cells in the hippocampal CA1 region were counted. Results The peak value, rising time and duration time of shock wave propagation on the division plate and head were 1369.74± 91.70g, 0.317± 0.037ms and 24.85± 2.53ms, 26.83± 3.09g, 0.901± 0.077ms and 104.21± 6.26ms respectively in injury group 1, 1850.11± 83.86g, 0.184± 0.031ms and 35.61± 2.66ms, 39.75± 3.14g, 0.607± 0.069ms and 132.44± 7.17ms in injury group 2 (P<0.01). After the injury, there was no abnormality in the anatomy, and brain damage markers NSE, S-100 β increased, reached the peak at 24 h, and they were highest in injury group 2 and lowest in control group with a statistically significant difference (P<0.05). The brain water content increased, reached the peak at 24h, and was the highest in injury group 2 and the lowest in control group with a statistically significant difference (P<0.05). No visible change was observed in the brain of injury groups, but acute neuronal damages to the cerebral cortex and hippocampus were observed under microscope. The neuronal density of hippocampal CA1 subfield was the lowest in injury group 2 and the highest in control group (P<0.05). Conclusions Shock wave propagation in solids from underwater explosion may lead to pathological changes such as brain edema and neuronal degeneration in rats, and cause mild traumatic brain injury in rats, thus, it is essential to strengthen prevention and care.

Hidrodinámica aplicada a la gestión y la conservación de ecosistemas marinos y costeros: Isla Gorgona, Océano Pacífico Colombiano / Hydrodynamics applied to the management and conservation of marine and coastal ecosystems: Gorgona Island, Colombian Pacific Ocean

Palmeras (Gorgona National Park) is one of the most important sites for sea turtle nesting in South and Central America. Because of the morphological processes affecting the beach, the turtle nests are increasingly exposed to the impact of waves and tides, threatening conservation. A study was made to determine the hydrodynamical processes of the zone adjacent to Playa Palmeras, which affects directly the morphodynamical behavior of the beach and thus the preservation of the nests. Field measurements and numerical modeling were used to obtain the general circulation patterns and thermohaline structure behavior in the area in order to determine the spatial and temporal variability of waves and its effects on the beach. A marked seasonality was found, both in the waves and the currents, influenced mainly by the meridional displacement of the ITCZ (Inter-Tropical Convergence Zone) and an interannual variability of the waves, associated with ENSO (El Niño Southern Oscillation). The flooding levels of the beach were determined and flooding probability maps were made, where safer sites to locate the turtle nests could be identified. These maps serve the officials responsible of monitoring the turtles as a tool to take decisions on moving the nests, since they have flood risk information for any point on the beach. The results show that the middle zone north of the beach is the one with the lowest risk of flooding, therefore the most appropriate zone to relocate nests that are in high risk areas. Rev. Biol. Trop. 62 (Suppl. 1): 133-147. Epub 2014 February 01.

Playa Palmeras (En el Parque Nacional Isla Gorgona) es uno de los sitios más importantes para la anidación de tortugas marinas en América del Sur y Centroamérica. Debido a procesos morfológicos que afectan la playa, los nidos de las tortugas se han visto cada vez más expuestos al impacto del oleaje y la marea, poniendo en riesgo la conservación de éstas especies. Se llevó a cabo un estudio para conocer los procesos hidrodinámicos de la zona costera en Playa Palmeras, de los cuales depende el comportamiento morfodinámico de la playa y la preservación de los nidos. Se usó modelación numérica y mediciones en campo para conocer la variabilidad espacio-temporal del oleaje y obtener los patrones generales de circulación y la estructura termohalina de la zona. Se encontró un marcado ciclo anual, tanto en el oleaje como en las corrientes, influenciado por la Zona de Convergencia Intertropical (ZCIT) y una variabilidad interanual del oleaje, asociada a El Niño Oscilación del Sur (ENSO). Se estimó la cota de inundación de la playa y se crearon mapas de probabilidad de inundación, identificando los sitios potencialmente más seguros para la anidación. Los resultados muestran que hacia el norte de la playa está la zona de menor riesgo.

Numerical simulation of pulse wave propagation and parameter analysis based on transmission line model / 医用生物力学

Objective To numerically simulate the propagation of pulse wave in human arterial tree by proposing a novel calculation method which combines a transmission line model and a recursive algorithm of input impedance, and to study the effects of individual differences and arterial tree parameters on pulse wave so as to provide references for the analysis on physiologic and pathologic characteristics of human arterial tree. MethodsThe transmission line model of human arterial tree was constructed, which consisted of 55-segment large and medium sized arteries. The recursive algorithm was applied to compute the input impedance of arterial tree at each point. The blood pressures and flows of 55 arteries were calculated and showed in the distribution graphs. Based on this method, the effects of height, heart rate, stroke volume, internal radius and wall thickness on pulse wave propagation and blood pressure distribution were compared. Results The simulation results were in good agreement with the general rules of pulse wave propagation. The propagation of pulse wave in arterial tree showed significantly different characteristics for different parameters. Conclusions The proposed method can effectively simulate the propagation of pulse wave in arterial tree and accurately reflect the effects of individual differences and hemodynamics parameters on pulse wave propagation, and it is an important assistant means for the pathophysiologic analysis and diagnosis of human arterial tree.