72 research outputs found
In a model of SAH-induced neurogenic fever, BAT thermogenesis is mediated by erythrocytes and blocked by agonism of adenosine A1 receptors
Neurogenic fever (NF) after subarachnoid hemorrhage (SAH) is a major cause
of morbidity that is associated with poor outcomes and prolonged stay in the
neurointensive care unit (NICU). Though SAH is a much more common cause
of fever than sepsis in the NICU, it is often a diagnosis of exclusion, requiring
significant effort to rule out an infectious source. NF does not respond to
standard anti-pyretic medications such as COX inhibitors, and lack of good
medical therapy has led to the introduction of external cooling systems that
have their own associated problems. In a rodent model of SAH, we measured
the effects of injecting whole blood, blood plasma, or erythrocytes on the
sympathetic nerve activity to brown adipose tissue and on febrile
thermogenesis. We demonstrate that following SAH the acute activation of
brown adipose tissue leading to NF, is not dependent on PGE , that
subarachnoid space injection of whole blood or erythrocytes, but not plasma
alone, is sufficient to trigger brown adipose tissue thermogenesis, and that
activation of adenosine A1 receptors in the CNS can block the brown adipose
tissue thermogenic component contributing to NF after SAH. These findings
point to a distinct thermogenic mechanism for generating NF, compared to
those due to infectious causes, and will hopefully lead to new therapies
MRI thermometry in phantoms by use of the proton resonance frequency shift method: application to interstitial laser thermotherapy
Power absorption and temperature control of multi-filament palladium-nickel thermoseeds for interstitial hyperthermia
In interstitial hyperthermia using ferromagnetic seeds, multi-filament seeds have gained interest because of a more effective power absorption than solid seeds. Palladium-nickel (PdNi) seeds composed of filaments with diameters in the range from 0.1 to 1.0 mm (maximally 90 filaments) have been investigated to find the conditions for optimal power absorption and temperature control. Magnetic and calorimetric experiments have shown that a decreasing filament radius results in a more effective power absorption. The power absorption approaches a common asymptote for high field intensities at all filament diameters. This asymptotic behaviour can be understood as a consequence of the approach of saturation magnetization of PdNi. The sharpness of the transition at the Curie temperature, which is a measure for the quality of temperature control, improves as the magnetic field strength increases, but it is limited by the asymptote of the power absorption. When the asymptote has been reached the quality of temperature regulation of a seed can only be improved by increasing the amount of PdNi, e.g. by increasing the number of filaments. Calculations of the power absorption, using the generally applied theory based on a linear relation between the magnetization of PdNi and the magnetic field strength, do not correspond quantitatively with experimental results for seeds having an induction number smaller than the 'optimal value' of 2.5. For these seeds the measured heat production is larger than the calculated on
Reliability of methods of assessing the degree of tuber attack by common scab of potatoes
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