Alterations of striatal dopamine receptor binding in Alzheimer disease are associated with Lewy body pathology and antemortem psychosis.

BACKGROUND: Lewy bodies (LB) are present in at least 20% to 30% of persons with Alzheimer disease (AD) and contribute to the risk of psychosis and to excess cognitive burden. OBJECTIVE: To determine whether altered striatal dopamine receptor binding is associated with LB and psychosis in AD. DESIGN: Postmortem case control. SETTING: Alzheimer's Disease Research Center at the University of Pittsburgh (Pa). PARTICIPANTS: Consecutive cases from the Alzheimer's Disease Research Center brain bank, neuroleptic free for at least 1 month prior to death, with neuropathologic diagnoses of AD with LB (AD + LB, n = 14), AD without LB (AD, n = 13), or normal brains (n = 8). MAIN OUTCOME MEASURES: Dopamine D1, D2, and D3 receptor densities, and affinities as determined by selective saturation binding studies in striatal tissue. RESULTS: Subjects with AD + LB, compared with those with AD, demonstrated increased D1 receptor density and decreased D2 and D3 receptor density. D3 receptor density was selectively increased, however, in AD subjects with a history of psychosis, independent of the presence or absence of LB. The effect of neuroleptic treatment on D3 binding was further examined in an additional group of subjects who had received neuroleptics near the time of death. Neuroleptic treatment reduced D3 affinity with no effect on D3 density. CONCLUSIONS: Alzheimer disease with LB is associated with selective alterations in dopamine receptor density, which may contribute to the distinct clinical profile of this group. The D3 receptor may be an important target of neuroleptic treatment of psychosis in AD.

Psychotic symptoms in Alzheimer's disease are not associated with more severe neuropathologic features.

Psychotic symptoms in Alzheimer's disease (AD) have been associated with increased rates of cognitive impairment and functional decline. Prior studies have been conflicting with regard to whether AD patients with psychosis (AD+P) have evidence of more severe neuropathologic findings at postmortem exam. We examined the severity of neuritic plaques and neurofibrillary tangles in six brain regions--middle frontal cortex, hippocampus, inferior parietal cortex, superior temporal cortex, occipital cortex, and transentorhinal cortex-in 24 AD+P subjects and 25 matched AD subjects without psychosis (AD-P). All analyses controlled for the presence of cortical Lewy bodies, and corrected for multiple comparisons. We found no significant associations between neuritic plaque and neurofibrillary tangle severity and AD+P, and no significant associations with any individual psychotic symptom. The association of AD+P with a more rapidly progressive course of AD appears to be mediated by a neuropathologic process other than increased severity of plaque and tangle formation.

Prophylaxis against thromboembolism in neurosurgical patients: a survey of current practice in the United Kingdom.

Venous thromboembolism is a life threatening, but preventable complication of major surgery. Many neurosurgical patients are at high risk of developing thromboembolic disease. A postal survey was undertaken of 44 UK neurosurgical centres to assess the use of physical and pharmacological methods of prophylaxis against thromboembolism. Thirty-five replies were received from 31 centres. Seventy-seven per cent of units used antiembolism stockings (TEDs) for elective surgery and 37% for emergency surgery; in approximately two-thirds of these units TEDs constituted the sole method of prophylaxis used during both elective and emergency surgery. Intermittent pneumatic compression (IPC) was utilized in 37 and 11% of units for elective and emergency surgery, respectively. Subcutaneous heparin was used in 32% of units perioperatively including 6% of emergency cases. These findings suggest that neurosurgical patients, who are at moderate to high risk of developing thromboembolic complications, may not receive effective prophylaxis; those undergoing emergency neurosurgery are less likely to receive any form of prophylaxis.

The effectiveness of internal oxygen transport in a mesophyte (Pisum sativum L.).

The effectiveness of oxygen movement through pea seedlings has been assessed firstly by assaying for radial oxygen loss along the roots using the cylindrical Pt electrode technique, and secondly by measuring root growth in various oxygen-free media.It was found that roots would grow in oxygen-free 3% agar to a length exceeding 20 cm, but when such plants were removed to oxygen-free 0.05% agar oxygen could not be detected in the apical segments in roots longer than 9.5 cm unless respiratory activity was curtailed by cooling.If the greater part of the root was retained in 3% agar and only the apical region exposed to 0.05% agar and assayed, oxygen loss always occurred. It was concluded that the 3% agar has a jacketing effect substantially reducing oxygen leakage from the root surface and thus allowing more oxygen to channel down to the apical regions.Root growth in unstirred air-saturated 0.05% agar matched the growth in oxygen-free 3% agar. Root growth in unstirred oxygen-free 0.05% agar was arrested at c. 9 cm.It is suggested that the effect produced by the aerated unstirred 0.05% agar is consistent with a jacketing effect mitigating oxygen loss from the root and that a growth of 9 cm in unstirred deoxygenated agar is consistent with a smaller jacketing effect due to the unstirred medium.It is proposed that the accumulation of respiratory tissue will eventually render inadequate any jacketing effect. Further aerobic development at this stage will require a supply of oxygen from the rooting medium.