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Biomedical subjects

Brian Thompson

Publications and source records attributed to Brian Thompson.

7 recordsLinked to original sources
PubMed2006

Protein kinase Calpha and sphingosine 1-phosphate-dependent signaling in endothelial cell.

Protein kinase C (PKC)-mediated signal transduction pathways convert extracellular stimulation into a variety of cellular functions. However, the role of various PKC isoforms in sphingosine 1-phosphate (S1P)-stimulated endothelial cells is not well understood. PKCalpha and PKCepsilon activity are increased in endothelial cell cultures, and S1P receptor transfection studies indicate S1P(3) stimulates PKCalpha and S1P1 leads to PKCepsilon activity. Infection of endothelial cells with dominant negative (DN)PKCalpha adenovirus reduces cell migration and greatly inhibits morphogenesis in cells stimulated with S1P. This effect is specific to PKCalpha, as infection with DN PKCepsilon does not alter either migration or morphogenesis. The PKC-specific chemical inhibitor GF109203X also inhibits these two responses. Infection of endothelial cells with dominant negative PKCalpha reduces S1P-induced calcium rise. This maximal rise requires calcium uptake, but it does not require enzymatic activity of the kinase. Pretreatment of these cells with the PKC-specific inhibitor GF109203X does not inhibit S1P-induced calcium rise. S1P-induced morphogenesis but not cell migration is critically dependent on extracellular calcium. Pretreatment of endothelial cells with phorbol 12-myristate 13-acetate for 5min abolishes S1P-stimulated rise in calcium but had little or no effect on migration. The PMA-inhibited calcium rise can be prevented by PKC inhibitor or infection with dominant negative PKCalpha.

Calcium↗
PubMed2005

Neuromechanical control of locomotion in the rat.

Rodent models are being extensively used to investigate the effects of traumatic injury and develop and assess the mechanisms of repair and regeneration. We present quantitative assessment of two-dimensional (2D) kinematics of overground walking and for the first time three-dimensional (3D) joint angle kinematics of all four limbs during treadmill walking in intact adult female Long-Evans rats. Gait cycle with subphases and intralimb and interlimb cyclograms are presented. Phase relationships between joint angles on a cycle-by-cycle basis and interlimb footfalls are assessed using a simple technique. Electromyogram (EMG) data from major flexor and extensor muscles for each of the hindlimb joints and elbow extensor muscles of the forelimbs synchronized to the 3D kinematics are also obtained. Overground walking kinematics, provides information on base of support, stride length, and hindfoot rotation. Treadmill walking kinematics indicate primarily monophasic angle trajectories for the hip and shoulder joints, weak double peak patterns for the knee and elbow joints, and a prominent double peak pattern for the ankle joints. Maximum flexion of the knee during swing precedes that of the ankle, which precedes that of the hip. A mild exercise regimen over 8 weeks does not alter the kinematics. EMG activity indicates specific relationships of the neural activity to joint angle kinematics. We find that the ankle flexors as well as the hip and elbow extensors maintain constant burst duration with changing cycle duration. Data and techniques described here are likely to be useful for quantitative assessment of altered gait and neural control mechanisms after neurotrauma.

Animals↗
PubMed2003

Food security in a world without borders.

The alleviation of poverty and the eradication of hunger and malnutrition are within reach. Considerable progress has been made over the past thirty years in reducing the numbers of the hungry, and projections over the next thirty years suggest that this progress will continue. The majority of developing countries have participated in this progress and have improved nutrition but there are significant regional differences. The current challenge is to build upon and accelerate the progress already made. Everyone is involved in this struggle against hunger and malnutrition, and to achieve these goals, global partnerships to enhance co-operation and co-ordination are being strengthened. Successful country experiences for improving food security and nutrition have demonstrated the importance of peace, political stability, and stable economic growth. There is also the need for increased foreign investment and increased ODA, particularly for African agriculture, debt relief, the better integration of LDCs in the global economy, their more secure access to markets and more equitable terms of trade, enhanced South-South co-operation, training and research and new high-yield and drought-resistant crop varieties. While all these have been commented on and recognised before, we must close the credibility gap in our political will by honouring our existing commitments for providing tangible benefits at the local level. For globalisation, the key issue is how the aggregate benefits of globalisation will be distributed and how to translate this into better nutrition. The LDCs, which are the most vulnerable and disadvantaged members of the international community, should be at the centre of this drive towards food security and take genuine ownership of policies, initiatives and activities to improve development. At the same time we need to succeed in making the developed world more aware of and responsive to the conditions of the LDCs. The most effective way to improve nutrition is through community nutrition programmes that encourage the full participation and co-operation of the entire community, maximise the utilisation of local resources, grasp the benefits of new technologies for productivity gains, involve multiple sectors and engage strong political commitment. The international community will be judged by its treatment of its most vulnerable members. The international community has repeatedly declared that it is dedicated to the eradication of poverty. Eliminating hunger and malnutrition is a vital first step. The political will to fight hunger and a firm commitment to invest in agriculture' and rural development are critical elements in any effort to achieve sustainable alleviation of hunger and poverty. This meeting and the WFS:FYL provide the additional impetus to meet the challenge of achieving food and nutritional security in a world without borders and free from hunger and malnutrition.

Food Supply↗
PubMed2002

A method for assessing balance control in rodents.

Recent research has shown that after spinal cord injury, the nervous system reorganizes. Nevertheless, little is known of the effects of neural reorganization, or plasticity, on motor skills. In this work, we present a method that utilizes kinetic and kinematic analysis, for investigating balance control in a rodent model of incomplete spinal cord injury. In this setup, the animals sit unconstrained on their hindlimbs on a platform while they eat a Fruitloop. In this posture, the animal is supporting all the body weight on its hindquarters removing the need for the animal to support itself on its hindlimb or maintain appropriate forelimb-hindlimb coordination for functional gait. The platform is bolted to a force transducer to provide measurements of shear forces in orthogonal directions in the horizontal plane. Reflective markers on the hip and tail of the animal indicate sway of the animals body. Using this method the effect of extensive 12 week long treadmill locomotor training on balance control in rodents with incomplete thoracic spinal cord contusion injury (iSCI) was assessed. One iSCI rat did not undergo training, while a sham injured and 3 other iSCI rats underwent training. The shear forces and sway produced by the injured untrained rat were much larger than for the sham or the injured but trained rats. Stance width assessed from overground walking in a separate study was also larger in the injured untrained rat. These data suggest that balance control may be improved by a locomotor training paradigm. This simple method for assessing balance control could thus be utilized in longitudinal studies to evaluate the effectiveness of pharmacological and locomotor therapies for repair and recovery after spinal cord injury.

Animals↗
PubMedDate not supplied

Using Multiple Antibiotic Resistance and land use characteristics to determine sources of fecal coliform bacterial pollution.

Multiple Antibiotic Resistance (MAR) analysis and regression modeling techniques were used to identify surface water areas impacted by fecal pollution from human sources, and to determine the effects of land use on fecal pollution in Murrells Inlet, a small, urbanized, high-salinity estuary located between Myrtle Beach and Georgetown, South Carolina, MAR analysis was performed to identify areas in the estuary that are impacted by human-source fecal pollution. Additionally, regression analysis was performed to determine if an association exists between land use and fecal coliform densities over the ten-year period from 1989 to 1998. Land-use variables were derived using Geographic Information System (GIS) techniques and were used in the regression analysis. MAR analyses were conducted by comparing the frequency and patterns of antibiotic resistance found in Escherichia coli isolates derived from surface water samples and from sewage sources in the Murrells Inlet sewage collection system. The MAR results suggest that the majority of the fecal pollution detected in the Murrells Inlet estuary may be from non-human sources, including fecal coliforms isolated from areas in close proximity to high densities of active septic tanks. A MAR Index, which measures the frequency of antibiotic resistance, was calculated for each of twenty-three water samples and nine sewage samples. The antibiotic resistance pattern comparisons were performed using cluster analysis. Although the MAR indices indicated that several surface water sites had potential human-source contamination, the cluster analysis suggests that only one sampling site had MAR patterns that were similar to those found in the sewage samples. This site was in close proximity to several large pleasure boats as well as a sewage collection system lift station, but was not near areas with active septic tanks. The results of the regression analysis also suggest that sewage sources and rainfall runoff from urbanized areas may contribute to fecal pollution in the estuary.

Drug Resistance, Multiple↗