Measuring Activated Clotting Time during Cardiac Catheterization and PCI: The Effect of the Sampling Site.

RESULTS: In 100 patients (mean age 67.1, 65% male), no significant differences were observed in ACT values obtained from the guiding catheter and arterial sheath (mean difference (MD) -18.3 s; standard deviation (SD) 96 s; P=0.067). Contrarily, ACT values obtained from the intravenous line were significantly lower as compared to values obtained from the guiding catheter (MD 25.7 s; SD 75.5; P=0.003) and arterial sheath (MD 39 s; SD 102.8; P < 0.001). Furthermore, ACT measurements from the arterial sheath showed a statistically significant proportional bias when compared to the other sampling sites (sheath vs. catheter, r = 0.761, P=0.001; sheath vs. IVL, r = 1.013, P < 0.001). CONCLUSIONS: The present study shows statistical significance and possibly clinically relevant variations between ACT measurements from different sample sites. Bias in ACT measurements may be minimized by using uniform protocols for ACT measurement during cardiac catheterization.

Increases in extracellular serotonin and dopamine metabolite levels in the basal forebrain during sleep deprivation.

The basal forebrain (BF) is an important mediator of cortical arousal, which is innervated by all ascending arousal systems. During sleep deprivation (SD) a site-specific accumulation of sleep factors in the BF results in increased sleep pressure (Kalinchuk et al., 2006; Porkka-Heiskanen et al., 1997; Porkka-Heiskanen et al., 2000). However, animals are able to stay awake and even increase their neuronal activity in the BF and cortex during SD, suggesting increased activity of the ascending arousal systems to counteract the effect of sleep pressure. This study used in vivo microdialysis to measure the effect of a 6h SD, by "gentle handling" in freely moving rats, on the extracellular levels of serotonin and dopamine metabolites (5-HIAA, and DOPAC and HVA respectively) in the BF. Additionally, because glucocorticoids can interact with monoaminergic neurotransmission, and SD could be stressful, corticosterone levels were measured. We found an increase in extracellular serotonin and dopamine metabolite levels (n=8, p≤0.05). No interaction between corticosterone and the monoaminergic systems was apparent. Extracellular corticosterone levels showed no increase during the first 3h of SD, and the subsequent increase (n=8, p≤0.05) did not result in values exceeding the normal diurnal maximum, indicating that no substantial stress was induced. The results demonstrate that SD increases extracellular dopamine and serotonin metabolites in the BF, suggesting increased activity of the ascending arousal systems. It remains to be investigated what the specific roles of the dopaminergic and serotonergic ascending arousal systems are in BF-mediated cortical arousal.

Characterization of sleep-wake patterns in a novel transgenic mouse line overexpressing human prepro-orexin/hypocretin.

AIM: Orexin/hypocretin peptides are expressed in the lateral hypothalamus and involved in the regulation of autonomic functions, energy homeostasis and arousal states. The sleep disorder narcolepsy, which is characterized by excessive daytime sleepiness and occurrence of sudden rapid eye movement (REM) sleep, is associated with a loss of orexin neurones. Our study investigated the effects of orexins on sleep-wake patterns in a novel transgenic mouse line overexpressing the human prepro-orexin (hPPO) gene under the control of its endogenous promoter. METHODS: Orexin overexpression was investigated by PCR, Southern and Western blotting as well as immunohistochemistry. Polysomnographic recordings were performed for analyses of sleep-wake patterns and for electroencephalographic activity during 24 h baseline and during and after 6 h of sleep deprivation (SD). RESULTS: Transgenic hPPO mice had increased expression of human prepro-orexin (hPPO) and orexin-A in the hypothalamus. Transgene expression decreased endogenous orexin-2 receptors but not orexin-1 receptors in the hypothalamus without affecting orexin receptor levels in the basal forebrain, cortex or hippocampus. Transgenic mice compared with their wild type littermates showed small but significant differences in the amount of waking and slow wave sleep, particularly during the light-dark transition periods, in addition to a slight reduction in REM sleep during baseline and during recovery sleep after SD. CONCLUSION: The hPPO-overexpressing mice show a small reduction in REM sleep, in addition to differences in vigilance state amounts in the light/dark transition periods, but overall the sleep-wake patterns of hPPO-overexpressing mice do not significantly differ from their wild type littermates.