The TRF model limited QT hysteresis in healthy, hypertensive, and pacemaker-dependent patients. In addition, an important finding of QT drift in patients with hypertension was identified. With further study in these and other diseased states, the TRF model may improve our ability to measure accurately cardiac repolarization and to determine arrhythmia risk.
The purpose of the study was to monitor the antioxidative effect of morine in alloxan-induced diabetes mellitus in laboratory rat. The animals were divided by random selection into two groups (n = 7). The treated group was given morine in oral doses of 10 mg/kg -1 in 0.5% solution of Methocel E5 once a day; the control diabetic group was given only the solution of Methocel E5. Once a week, selected laboratory indices were determined in all animals (glucose, urea and cholesterol levels in serum, total glucose and protein losses through urine); diuresis as well as antioxidative enzymes (superoxiddismutase, glutathione peroxidase); total antioxidative capacity and malondialdehyde level in the blood. On the 20 th day the animals were exsanguinated and kidney tissue and pancreas samples were taken for histopathological analysis.We found a significant increase (p ≤ 0.05) of the glutathione peroxidase catalytic activity in the treated group compared to control diabetic group. There was also a highly significant increase (p ≤ 0.01) of total antioxidative capacity in the treated group compared to control diabetic group. A significant decrease (p ≤ 0.05) of malondialdehyde level was identified in the treated group compared to the control diabetic group. The superoxiddismutase catalytic activity involved nonsignificant changes. A significant decrease (p ≤ 0.05) of cholesterol level in serum was identified in the treated group compared to control diabetic group. Other examined laboratory parameters did not exhibit significant changes.Biochemical indices followed in this study indicated a protective antioxidative effect of morine. However, the results of histopathological examination did not correlate with them.
A novel model for the coupling between ventricular repolarisation and heart rate (QT/RR) is presented. It is based upon a transfer function (TRF) formalism that describes the static and dynamic properties of this coupling, i.e., the behaviour after a sudden change in heart rate. Different TRF models were analysed by comparing their capability to describe experimental data collected from 19 healthy volunteers using several RR stimulation protocols: (i) rest with deep breathing at 0.1 Hz; (ii) tilt with controlled breathing at 0.1 and 0.33 Hz; and (iii) cycling. A search for the best TRF led to unambiguous identification of a three-parameter model as the most suitable descriptor of QT/RR coupling. Compared with established static models (linear or power-law), our model predictions are substantially closer to the experimental results, with errors approximately 50% smaller. The shape of the frequency and step responses of the TRF presented is essentially the same for all subjects and protocols. Moreover, each TRF may be uniquely identified by three parameters obtained from the step response, which are believed to be of physiological relevance: (i) gain for slow RR variability; (ii) gain for fast RR variability; and (iii) time during which QT attains 90% of its steady-state value. The TRF successfully describes the behaviour of the RR control following an abrupt change in RR interval, and its parameters may offer a tool for detecting pharmacologically induced changes, particularly those leading to increased arrhythmogenic risk.
The purpose of the study was to monitor the antioxidative effect of morine in the conditions of ischemia-reperfusion of laboratory rat kidney tissue. The animals were divided by random selection into two groups (n = 7). The treated group was given morine in peroral doses of 10 mg·kg -1 in 0.5% solution of methylcellulose (Methocel) E5 once a day, the control group was given only the solution of Methocel E5. After medication was finished on the 20 th day all animals were subject to kidney tissue ischemia (60 minutes) followed by reperfusion (10 minutes). All animals were subsequently exsanguinated, organs were recovered for histopathological examination and single identification of superoxiddismutase, glutathion peroxidase, total antioxidative capacity; and malondialdehyde level in the blood was carried out. We discovered a significant increase (p ≤ 0.05) of the superoxiddismutase catalytic activity in the treated group compared to the group of control ischemia-reperfusion. There was also a highly significant increase (p ≤ 0.01) of total antioxidative capacity in the treated group compared to the group of control ischemia-reperfusion. The glutathion peroxidase catalytic activity embodied non-significant changes when comparing the treated group and control group. A significant decrease (p ≤ 0.05) of malondialdehyde level was identified in the treated group compared to the group of control ischemia-reperfusion. The results of biochemical examination show a protective antioxidative effect of morine. The results of histopathological examination support this assumption. Antioxidants, superoxiddismutase, glutathion peroxidase, malondialdehyde
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