MAPT STUDY: A MULTIDOMAIN APPROACH FOR PREVENTING ALZHEIMER'S DISEASE: DESIGN AND BASELINE DATA.

OBJECTIVE: The Multidomain Alzheimer Preventive Trial (MAPT study) was designed to assess the efficacy of isolated supplementation with omega-3 fatty acid, an isolated multidomain intervention (consisting of nutritional counseling, physical exercise, cognitive stimulation) or a combination of the two interventions on the change of cognitive functions in frail subjects aged 70 years and older for a period of 3 years. Ancillary neuroimaging studies were additionally implemented to evaluate the impact of interventions on cerebral metabolism (FDG PET scans) and atrophy rate (MRIs), as well as brain amyloïd deposit (AV45 PET scans). DESIGN PATIENTS: 1680 subjects (mean age: 75.3 years; female: 64.8 %), enrolled by 13 memory clinics, were randomized into one of the following four groups: omega-3 supplementation alone, multidomain intervention alone, omega-3 plus multidomain intervention, or placebo. Participants underwent cognitive, functional and biological assessments at M6, M12, M24 and M36 visits. The primary endpoint is a change of memory function at 3 years, as assessed by the Free and Cued Selective Reminding test. All participants will be followed for 2 additional years after the 3-years intervention (MAPT PLUS extension study). INTERVENTIONS: 1/Omega-3 supplementation: two soft capsules daily as a single dose, containing a total of 400 mg docosahexaenoic acid (DHA), i.e., 800 mg docosahexaenoic acid per day, for 3 years. 2/ Multidomain intervention: collective training sessions conducted in small groups (6-8 participants) in twelve 120-minute sessions over the first 2 months (two sessions a week for the first month, and one session a week the second month) then a 60-minute session per month in the following three areas: nutrition, physical activity, and cognition until the end of the 3 years. In addition to the collective sessions, individualized preventive outpatient visits exploring possible risk factors for cognitive decline are performed at baseline, M12 and M24. BASELINE POPULATION: For cognition, the mean MMSE at baseline was 28.1 (± 1.6). About 58% and 42% of participants had a CDR score equal to 0 and 0.5, respectively. Regarding mobility status, 200 (11.9%) had a 4-m gait speed lower or equal to 0.8 m/s. According to the Fried criteria, 673 (42.1%) participants were considered pre frail, and 51 (3.2%) frail. The red blood cell DHA content was 26.1 ± 8.1 µg/g. Five hundred and three participants underwent baseline MRI. AV45 PET scans were performed in 271 individuals and preliminary results showed that 38.0% had a cortical SUVR > 1.17, which gave an indication of significant brain amyloïd deposit. DISCUSSION: The MAPT trial is presently the first largest and longest multidomain preventive trial relevant to cognitive decline in older adults with subjective memory complaints. The multidomain intervention designed for the MAPT trial is likely to be easily implemented within the general population.

Photobleaching of asymmetric cyanines used for fluorescence imaging of single DNA molecules.

The photobleaching of the cyanine dyes YO and YOYO has been investigated for both free and DNA-bound dyes, using absorption and fluorescence spectroscopy coupled with fluorescence microscopy. For the free dyes, the nature of the reactive species involved in the photodegradation process is different for the monomer and the dimer, as shown by scavenger studies. For DNA-bound dyes, photoinduced fading of the visible absorption band occurs by different pathways depending on the drug binding mode and can be attenuated by appropriate scavengers. However, none of these scavengers were found to have any significant effect on the photobleaching of dye fluorescence. It appears that the reduction of fluorescence intensity comes from a quenching of the dye fluorescence by modified DNA bases, possibly 8-oxo-7,8-dihydro-2'-deoxyguanosine.

Differentiation of O-acetyl and O-carbamoyl esters of N-acetyl-glucosamine by decomposition of their oxonium ions. Application to the structure of the nonreducing terminal residue of Nod factors.

Nod factors are substituted N-acyl chito-oligomers secreted by plant symbiotic bacteria of the Rhizobium family. Substitutions on the oligosaccharide core specify their recognition by host plants. A method using tandem mass spectrometry is proposed to locate the O-acetyl and O-carbamoyl substituents on the nonreducing terminal residue of the chito-oligomers. As model compounds, all the positional isomers of monoacetyl and monocarbamoyl esters of 1-O-methyl-N-acetyl-alpha-D-glucosamine were synthesized. Oxonium ions (MH - CH3OH)+ were generated by liquid secondary ion mass spectrometry (LSIMS) and their decomposition was recorded on a tandem magnetic instrument. Large differences were observed in the relative abundances of ions resulting from elimination of water and of the O-ester substituent from metastable oxonium ions. Deuterium exchange reactions indicated parallel elimination pathways involving either exchangeable or carbon-linked hydrogens. The intensity ratios of some of the ions generated by collisions with helium atoms allowed the isomers to be distinguished. The main dissociation routes were identified. Metastable and collision-induced decomposition of the B1 ions from Nod factors of Sinorhizobium meliloti and Azorhizobium caulinodans resembled that of the 6-O-substituted N-acetylglucosamine models. Decomposition of the B1 ion from Mesorhizobium loti and Rhizobium etli Nod factors, was similar to that of 3-O-carbamoyl N-acetyl-glucosamine and different to that of the 4-O isomer. 6-O- and 3-O-carbamoylation specified by the nodU and nolO genes, respectively, of Rhizobium. sp. NGR234 were confirmed.