Histological markers in nasal mucosa of patients with Alzheimer's disease

Neuropathological changes such as dystrophic neurites and the presence of abnormal tau protein in the olfactory system, including primary sensory cells and nerve fibres have previously been demonstrated in nasal mucosa tissue of patients with Alzheimer's disease (AD). These changes were detected in autopsy-derived material from histopathologically confirmed AD cases as well as in biopsy tissue from clinical severely ill AD patients. To investigate the potential usefulness for the early diagnosis of AD, we obtained biopsy tissue from olfactory mucosa from 5 clinically mild to moderate AD patients and stained for the presence of tau or beta-amyloid by immunocytochemistry using a panel of specific antibodies. No positive staining was found in any of the cases. For comparison, post-mortem olfactory tissue from AD patients with severe neuropathological changes (widespread neurofibrillary tangles and amyloid in the brain) was investigated, in these severe cases, tau immunoreactivity was found in fine nerve fibres in the lamina propria and in a few olfactory epithelial cells. These results are consistent with other reports showing that cytoskeletal changes and tau pathology in the olfactory epithelium are not primary (or specific) features of AD and may occur predominantly in late stages of the disease

High susceptibility to fatty liver disease in two-pore channel 2-deficient mice

Endolysosomal organelles play a key role in trafficking, breakdown and receptor-mediated recycling of different macromolecules such as low-density lipoprotein (LDL)-cholesterol, epithelial growth factor (EGF) or transferrin. Here we examine the role of two-pore channel (TPC) 2, an endolysosomal cation channel, in these processes. Embryonic mouse fibroblasts and hepatocytes lacking TPC2 display a profound impairment of LDL-cholesterol and EGF/EGF-receptor trafficking. Mechanistically, both defects can be attributed to a dysfunction of the endolysosomal degradation pathway most likely on the level of late endosome to lysosome fusion. Importantly, endolysosomal acidification or lysosomal enzyme function are normal in TPC2-deficient cells. TPC2-deficient mice are highly susceptible to hepatic cholesterol overload and liver damage consistent with non-alcoholic fatty liver hepatitis. These findings indicate reduced metabolic reserve of hepatic cholesterol handling. Our results suggest that TPC2 plays a crucial role in trafficking in the endolysosomal degradation pathway and, thus, is potentially involved in the homoeostatic control of many macromolecules and cell metabolites

[Psychopharmacotherapy of the elderly]

Pharmacokinetic and pharmacodynamic changes related to aging and age-associated disorders influence the choice and dosage of psychotropic drugs in the treatment of the elderly. Renal and hepatic clearance is limited and the sensitivity to pharmacological effects is increased. To avoid side effects most psychotropic drugs should be introduced in a 'start low--go slow' approach. The final dose may also be lower than in the treatment of younger adults. Drug interactions may occur as a consequence of a complex medication. Peculiarities of the treatment of older adults with antidepressants, antipsychotics, anxiolytics, mood-stabilizers and hypnotics is described

[Antidementia drugs]

The pharmacological treatment of dementias aims to improve cognitive deficits, activities of daily living and behavioural and psychiatric symptoms. The weighting of theses therapeutic aims varies with disease progression. Behavioural symptoms may dominate especially in the more severe stages of the disease and may further deteriorate global functional level of the patient. Today there is no causal therapy for Alzheimer's disease (AD). Based on preclinical disease models novel therapeutic approaches are under development that target the beta-amyloid and tau protein metabolism. Some of them aim to inhibit the formation, aggregation and toxicity of beta-amyloid peptides or promote their clearance from the brain. Others inhibit the formation of neurofibrillary tangles or have neuroprotective effects. Active or passive immunisation against beta-amyloid may be a very specific and effective approach. The efficacy of acetylcholine esterase inhibitors (AchEI) in the treatment of mild to moderate AD is well documented. They are first line therapeutics in the treatment of the disease and lead to a delay of symptomatic progression. Memantine is effective in the treatment of moderate to severe stages of AD. The evidence for the treatment of vascular dementia is comparatively weak. However, positive effects have been shown for all available AchEI and memantine. Non pharmacological therapy is an indispensable part of the treatment of dementia patients and should be adapted to the individual needs of the patient in the respective stage of the disease. The efficacy of antipsychotics in the treatment of behavioural and psychiatric symptoms of dementia is limited. These drugs are associated with increased morbidity and mortality in dementia patients. Therefore, their application should be based on a critical and individual evaluation of risks and benefits

Mismatch and conflict : neurophysiological and behavioral evidence for conflict priming

Conflict-related cognitive processes are critical for adapting to sudden environmental changes that confront the individual with inconsistent or ambiguous information. Thus, these processes play a crucial role to cope with daily life. Generally, conflicts tend to accumulate especially in complex and threatening situations. Therefore, the question arises how conflict-related cognitive processes are modulated by the close succession of conflicts. In the present study, we investigated the effect of interactions between different types of conflict on performance as well as on electrophysiological parameters. A task-irrelevant auditory stimulus and a task-relevant visual stimulus were presented successively. The auditory stimulus consisted of a standard or deviant tone, followed by a congruent or incongruent Stroop stimulus. After standard prestimuli, performance deteriorated for incongruent compared to congruent Stroop stimuli, which were accompanied by a widespread negativity for incongruent versus congruent stimuli in the event-related potentials (ERPs). However, after deviant prestimuli, performance was better for incongruent than for congruent Stroop stimuli and an additional early negativity in the ERP emerged with a fronto-central maximum. Our data show that deviant auditory prestimuli facilitate specifically the processing of stimulus-related conflict, providing evidence for a conflict-priming effect