[14C]acetate incorporation by cultured normal, familial hypercholesterolemia and Down's syndrome fibroblasts

Down syndrome, Alzheimer disease, and cerebral amyloid angiopathy: The complex triangle of brain amyloidosis

Down syndrome (DS) is the main genetic cause of intellectual disability worldwide. The overexpression of the Amyloid Precursor Protein, present in chromosome 21, leads to β-amyloid deposition that results in Alzheimer disease (AD) and, in most cases, also to cerebral amyloid angiopathy (CAA) neuropathology. People with DS invariably develop the neuropathological hallmarks of AD at the age of 40, and they are at an ultra high risk for suffering AD-related cognitive impairment thereafter. In the general population, cerebrovascular disease is a significant contributor to AD-related cognitive impairment, while in DS remains understudied. This review describes the current knowledge on cerebrovascular disease in DS and reviews the potential biomarkers that could be useful in the future studies, focusing on CAA. We also discuss available evidence on sporadic AD or other genetically determined forms of AD. We highlight the urgent need of large biomarker-characterized cohorts, including neuropathological correlations, to study the exact contribution of CAA and related vascular factors that play a role in cognition and occur with aging, their characterization and interrelationships. DS represents a unique context in which to perform these studies as this population is relatively protected from some conventional vascular risk factors and they develop significant CAA, DS represents a particular atheroma-free model to study AD-related vascular pathologies. Only deepening on these underlying mechanisms, new preventive and therapeutic strategies could be designed to improve the quality of life of this population and their caregivers and lead to new avenues of treatment also in the general AD population.

Advanced oxidation protein products (AOPP) and high-sensitive C-reactive protein (hs-CRP) in an “atheroma-free model”: Down's syndrome

Murdoch et al. in 1977 called Down syndrome an "atheroma-free model." In this preliminary study, we investigated advanced oxidation protein products (AOPP) and high-sensitive C-reactive protein (hs-CRP) in 47 age-matched Down syndrome patients and 20 age-matched healthy controls. In these healthy patients, we detected no new biochemical risk factors for atherosclerosis, such as AOPP and hs-CRP, so risks are probably considerably lower.

LDL receptor expression on T lymphocytes in old patients with Down syndrome

Background

In Down syndrome patients several metabolic abnormalities have been reported, some involving the lipid metabolism. The level of LDL in plasma is the major determinant of the risk of vascular disease. There appear to be no studies on the LDL receptor in Down syndrome patients.

Methods

Flow cytometric methods for measuring the LDL receptor in peripheral blood mononuclear cells (PBMC) can identify patients with hypercholesterolemia. We applied this method in 19 old patients with Down syndrome and 23 healthy controls.

Results

Down syndrome patients had high levels of triglycerides and low levels of HDL, and high levels of CRP. We also found a down-regulation of LDL receptor expression.

Conclusions

Down syndrome patients show no increase in the frequency of cardiovascular disease. The low incidence in cardiovascular disease despite the low level of HDL, high levels of CRP and reduction of LDL receptor expression lead to the conclusion that either these are not risk factors in these patients or that other risks factors – not yet identified – are considerably lower.

Time response of cholesterol synthesis inhibition by compactin-related compounds. In vitro quantitation of the "escape phenomenon"

The time course of the inhibition of cholesterol synthesis by low and high doses of mevinolin and monacolin X were studied in normal human skin fibroblasts, fibroblasts without low density lipoprotein receptor and HepG2 hepatoma cells. Low doses of the inhibitors (0.2 ng/mL) caused a sharp decrease in the rate of cholesterol synthesis during the first 2-3 h, which gradually increased to about 40% during the next 6 h. Further incubation led to a decrease or stabilization of the cholesterol synthesis rate. High doses of the drugs (100 mg/mL) strongly inhibited cholesterol synthesis during the first 2-3 h, followed by a moderate increase during the next 20 h. No drug or tissue selectivity was observed.