71 research outputs found
Regional myocardial blood flow, function and metabolism using phosphorus-31 nuclear magnetic resonance spectroscopy during ischemia and reperfusion in dogs
Postreperfusion regional myocardial dysfunction may be associated with depletion of high energy phosphate compounds during ischemia and with their relatively slow repletion during reperfusion. However, few studies have correlated relatively rapid changes in regional myocardial function (sonomicrometers) and blood flow (microspheres) with high energy phosphate concentrations measured using phosphorus-31 nuclear magnetic resonance spectroscopy in intact large animal models of regional myocardial ischemia. The left anterior descending coronary artery of mongrel dogs was abruptly occluded for 17.1 ± 1.9 minutes and then completely released; measurements were made for an additional 22 minutes. Transmural blood flow decreased from 1.07 ± 0.25 to 0.25 ± 0.10 ml/(min × g) and holosystolic expansion was observed in all dogs (segmental systolic shortening decreased from 9.3 ± 3.7 to −6.3 ± 6.0%). Phosphocreatine (PCr) measured during 4.4 minute sampling intervals decreased to steady state within the first sampling period after occlusion and was 45.9 ± 17.0% of control at the end of the occlusion, whereas beta-adenosine triphosphate (beta-ATP) reached its lowest level early after reperfusion (72.7 ± 13.3% of control). The ratio of PCr to inorganic phosphate (Pi) decreased during the occlusion (3.34 ± 0.75 versus 1.01 ± 0.61) but returned to control level early during reperfusion. The ratio of PCr to beta-ATP also decreased during coronary occlusion (2.16 ± 0.39 versus 1.29 ± 0.39) but did not return to control level during reperfusion.Significant correlations were observed between the intensity of ischemia (reduced blood flow) and reductions in regional contractile function, PCr, beta-ATP, myocardial pH and the increase in Pi during the coronary occlusion. Also during ischemia, there were significant correlations between regional contractile function and both myocardial pH and Pi. PCr returned to control level rapidly after reperfusion (95.9 ± 13.2% of control in less than 5 minutes of reperfusion) whereas beta-ATP recovered only partially after 22 minutes (80.0 ± 17.5% of control). The correlation between the fraction of control beta-ATP and the fraction of control regional function at this time was r = 0.84 (p = 0.017).These results demonstrate metabolic correlates to regional myocardial ischemia in an intact dog model using phosphorus-31 spectroscopy. Additionally during reperfusion, beta-ATP, but not PCr, could be associated with the recovery of regional segmental contractile function
Drug safety Africa: An overview of safety pharmacology & toxicology in South Africa.
This meeting report is based on presentations given at the first Drug Safety Africa Meeting in Potchefstroom, South Africa from November 20-22, 2018 at the North-West University campus. There were 134 attendees (including 26 speakers and 34 students) from the pharmaceutical industry, academia, regulatory agencies as well as 6 exhibitors. These meeting proceedings are designed to inform the content that was presented in terms of Safety Pharmacology (SP) and Toxicology methods and models that are used by the pharmaceutical industry to characterize the safety profile of novel small chemical or biological molecules. The first part of this report includes an overview of the core battery studies defined by cardiovascular, central nervous system (CNS) and respiratory studies. Approaches to evaluating drug effects on the renal and gastrointestinal systems and murine phenotyping were also discussed. Subsequently, toxicological approaches were presented including standard strategies and options for early identification and characterization of risks associated with a novel therapeutic, the types of toxicology studies conducted and relevance to risk assessment supporting first-in-human (FIH) clinical trials and target organ toxicity. Biopharmaceutical development and principles of immunotoxicology were discussed as well as emerging technologies. An additional poster session was held that included 18 posters on advanced studies and topics by South African researchers, postgraduate students and postdoctoral fellows
Imprints of Short Distance Physics On Inflationary Cosmology
We analyze the impact of certain modifications to short distance physics on
the inflationary perturbation spectrum. For the specific case of power-law
inflation, we find distinctive -- and possibly observable -- effects on the
spectrum of density perturbations.Comment: Revtex 4, 3 eps figs, 4 page
Influence of repeated anaesthesia on physiological parameters in male Wistar rats: a telemetric study about isoflurane, ketamine-xylazine and a combination of medetomidine, midazolam and fentanyl
Improved cider fermentation performance and quality with newly generated Saccharomyces cerevisiae × Saccharomyces eubayanus hybrids
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