EP-1526: Analysis of dose deposition in lung lesions: a modified PTV for a more robust optimization

n/

Electrophysiological effects of systemic hypothermia on the right and left ventricles in sheep: Role in arrhythmogenesis

Hypothermia alters myocardial electrophysiology and can result in ventricular arrhythmias. Therapeutic hypothermia is used to mitigate neurological injury after cardiac arrest with moderate hypothermia (32-340C) to minimise the risk ventricular arrhythmias. The mechanisms responsible remain poorly understood and we thus sought to examine the arrhythmogenicity of hypothermia in a large animal model. Ten sheep were cooled systemically using an extracorporeal circuit. Surface 12 lead ECGs, and epicardial and transmural potentials (N=220) were recorded. Potentials were recorded during sinus rhythm (SR) and ventricular pacing (VP). Local activation time (AT), recovery time (RT), and corrected activation-recovery intervals (ARIc) were measured. Hypothermia resulted in a prolonged AT, RT and ARIc during SR/VP. Local AT, RT and ARIc heterogeneity was increased particularly during VP. The main increase in heterogeneity during SR occurred between normothermia and 340C. Depolarisation of the lateral LV wall was significantly more affected by hypothermia. Hypothermia resulted in ST elevation predominantly over the infero-basal region of the heart and was associated with localised slowing of depolarisation and more rapid depolarisation. Hypothermia was not more arrhythmogenic at 300C compared with 340C during SR which may support deeper hypothermia in post cardiac arrest situations

Expression analysis using oligonucleotide microarrays in mice lacking bradykinin type 2 receptors

We recently conducted detailed cardiovascular and blood pressure-related phenotypic studies of mice lacking the bradykinin-B(2) receptor and were unable to identify a phenotype despite insensitivity to infused bradykinin. We therefore used oligonucleotide microarray analysis of some 12 000 genes and expressed sequence tags to identify molecular mechanisms that might be involved in compensating for the lack of a functional B(2) receptor in the kidneys of the mice. We identified 2 gene families that may have an impact on cardiovascular regulation and the bradykinin pathway. A water transport channel in the kidney, AQP4, was downregulated in the mice, whereas other members of the gene family did not show differences in expression levels. In addition, a number of serine proteases were upregulated in B(2) receptor-deficient mice. These genes are all located within a gene cluster on mouse chromosome 7. The findings were verified by an independent method. We suggest that microarray analysis has usefulness in elucidating otherwise unappreciated compensatory signaling pathways

Expression analysis using oligonucleotide microarrays in mice lacking bradykinin type 2 receptors

We recently conducted detailed cardiovascular and blood pressure-related phenotypic studies of mice lacking the bradykinin-B(2) receptor and were unable to identify a phenotype despite insensitivity to infused bradykinin. We therefore used oligonucleotide microarray analysis of some 12 000 genes and expressed sequence tags to identify molecular mechanisms that might be involved in compensating for the lack of a functional B(2) receptor in the kidneys of the mice. We identified 2 gene families that may have an impact on cardiovascular regulation and the bradykinin pathway. A water transport channel in the kidney, AQP4, was downregulated in the mice, whereas other members of the gene family did not show differences in expression levels. In addition, a number of serine proteases were upregulated in B(2) receptor-deficient mice. These genes are all located within a gene cluster on mouse chromosome 7. The findings were verified by an independent method. We suggest that microarray analysis has usefulness in elucidating otherwise unappreciated compensatory signaling pathways

Expression analysis using oligonucleotide microarrays in mice lacking bradykinin type 2 receptors

We recently conducted detailed cardiovascular and blood pressure-related phenotypic studies of mice lacking the bradykinin-B(2) receptor and were unable to identify a phenotype despite insensitivity to infused bradykinin. We therefore used oligonucleotide microarray analysis of some 12 000 genes and expressed sequence tags to identify molecular mechanisms that might be involved in compensating for the lack of a functional B(2) receptor in the kidneys of the mice. We identified 2 gene families that may have an impact on cardiovascular regulation and the bradykinin pathway. A water transport channel in the kidney, AQP4, was downregulated in the mice, whereas other members of the gene family did not show differences in expression levels. In addition, a number of serine proteases were upregulated in B(2) receptor-deficient mice. These genes are all located within a gene cluster on mouse chromosome 7. The findings were verified by an independent method. We suggest that microarray analysis has usefulness in elucidating otherwise unappreciated compensatory signaling pathways

Characterization of PVA-GTA Fricke gels dosimeters using MRI and optical techniques in X-rays external radiation therapy

The purpose of this work is to study the dependence of the dosimetric properties of poly(vinyl-alcohol)-glutaraldehyde Fricke gel dosimeters (PVA-GTA-FG) both on the irradiation temperature and on temperature changes possibly occurring between the irradiation and readout phases. Such effects were investigated by means of MRI and optical absorbance measurements. The results did not reveal any significant dependence of the sensitivity of the dosimeters on the irradiation temperature in the investigated interval (20\u25e6C-35\u25e6C). In contrast, the effect of the holding temperature may be not negligible. Additionally, PVA-GTA-FG proved to be nearly tissue-equivalent and characterized by a response independent on the energies and dose-rates in the investigated intervals (0-15 Gy). These findings suggested that PVA-GTA-FG are promising tools for clinical dosimetry