St Lucy's Hospital

The noradrenergic systems in the brain maintain cognitive functions including attention/concentration and establishment of long-term memory. In addition, hypofunction of noradrenergic systems is supposed to be involved in the pathophysiology of Alzheimer's disease. In this study, we tried to examine the possible associations of concentrations of basal salivary 3-methoxy-4-hydroxyphenylglycol (sMHPG), a major metabolite of noradrenaline, and brain volume changes during 4 years in elderly people living in a rural community. The survey was conducted twice in Kurokawa-cho, Imari, Saga Prefecture, Japan, among people aged 65 years and older. We collected data from 226 residents. Measurements of sMHPG and brain MRIs were collected at Time 1 (2005-2007). Follow-up brain MRIs were taken at Time 2 (2009-2011). A total of 70 participants (18 men, mean age 71.9 ± 4.8 years; 52 women, mean age 72.0 ± 4.3 years) completed this survey. Concentrations of sMHPG at baseline were divided into two groups using the mean value (12.83 ng/ml). We compared the brain volumes between groups with higher and lower sMHPG concentrations over time using voxel-based morphometry implemented with statistical parametric mapping. In participants with higher sMHPG concentrations at baseline, brain volumes including right precuneus were significantly larger 4 years after baseline than those with lower sMHPG concentrations at baseline. No interaction between sMHPG concentration and MRI acquisition interval was found. Our results suggest that higher sMHPG concentrations in elderly people might be associated with maintenance of brain volume, especially in brain regions closely related to cognitive function.

The influence of the immunoreactive endogenous digoxin-like factor (IEDLF) on the systemic toxic effects of bupivacaine was studied in a rodent model. During 5 weeks, IEDLF secretion was promoted in 10 Wistar male rats by allowing them to drink saline 0.5% in place of water. Ten other animals drank desionized water (control). At the time of experimentation, the two groups of rats were mixed to allow blind observation. Anesthesia was induced with barbiturate, and controlled ventilation was started. A blood sample was drawn for IEDLF assessment just before bupivacaine was infused at a constant rate of 2 mg/kg per minute. Data were analyzed for statistical significance using Student's t-test. A p value less than 0.05 was considered significant. Two rats in the saline group died during the induction of anesthesia. An IEDLF activity was found in the eight remaining rats in this group. Threshold doses of bupivacaine's toxic effects (first ventricular arrhythmia, first seizure activity, 25% fall of baseline heart rate, 25% of baseline mean arterial blood pressure, isoelectric electroencephalogram) were significantly lower for the rats with an endogenous digoxin-like activity. There were, however, no significant differences in the lethal dose of bupivacaine. In hyperoxic nonacidotic male rats, IEDLF increases the cardiac and central nervous system toxicity of bupivacaine.