👤 U R Rapp

Arterial stiffness is a contributor to cognitive decline. Pressure time constants (PTCs: PTC1, PTC2) are new measures of arterial compliance (inverse of stiffness) which are based on a Windkessel model of arterial pulse pressure waveforms. The methodology for PTCs is open-source and scalable. We evaluated the cross-sectional association between PTCs from radial artery pressure waveforms and cognitive performance: Global cognitive function (Cognitive Abilities Screening Instrument, CASI; score range 0-100); processing speed (Digit Symbol Coding, DSC; 0-133); and working memory (Digit Span, DS; 0-30). Among 3134 adults from 6 U.S. communities in 2010-2012 (aged 54-94 years; 47% male; 41% White, 25% Black, 23% Hispanic/Latino, 12% Chinese), the mean ± SD was 283 ± 127 ms for PTC1, 85 ± 31 ms for PTC2, 89 ± 8 for CASI, 51 ± 18 for DSC, and 15 ± 4 for DS. In the entire sample (after adjustment for community, race/ethnicity, and variables in the dementia score called "Cardiovascular Risk Factors, Aging, and Incidence of Dementia"), neither PTC1 nor PTC2 was associated with CASI, DSC, or DS. In exploratory analyses, after adjustment, one SD higher PTC2 was associated with a 1.4 (95% confidence interval: 0.4, 2.5; p = 0.004) higher mean DSC score among the subset with at least one APOE-ε4 allele (N = 828) and a 0.8 (0.1, 1.5; p = 0.03) higher mean DSC score among those 65 years and older (N = 2020). Higher radial artery PTC2 (lower arterial stiffness) was associated with faster processing speed among carriers of APOE-ε4 and older adults. Future work should investigate the association of PTCs with other indicators of brain health. Show less

Aging is the strongest risk factor for dementia; however, few studies have examined the association of biological aging with incident dementia. We analyzed 6069 cognitively unimpaired women (mean age = 70.0 ± 3.8 years) in the Women's Health Initiative Memory Study to examine the association of accelerated biological aging, measured with second and third-generation epigenetic clocks (AgeAccelPheno and AgeAccelGrim2, and DunedinPACE, respectively) with incident mild cognitive impairment (MCI) and probable dementia. Multivariable Cox proportional hazards models adjusted for age, education, race, ethnicity, smoking, hormone therapy regimen, physical activity, body mass index, and estimated white blood cell counts. For comparison, we also examined first-generation epigenetic clocks (AgeAccelHorvath; AgeAccelHannum). We evaluated effect modification by age, race/ethnicity, hormone therapy regimen, menopause type (natural vs. surgical), and APOE ε4 carriage. There were 1307 incident MCI or probable dementia events over a median follow-up of 9.3 (25th percentile = 6.1, 75th percentile = 16.1) years. The adjusted HRs (95% CI; p-value) for incident MCI/probable dementia per one-standard deviation increment were 1.07 (1.01-1.15; p = 0.03) for DunedinPACE, 1.11 (1.02-1.20; p = 0.01) for AgeAccelGrim2, and 1.01 (0.95-1.07; p = 0.74) for AgeAccelPheno. Only AgeAccelGrim2 remained significant under the Bonferroni-corrected threshold for significance (p < 0.02). Other epigenetic clocks were not associated with incident MCI/probable dementia. There was no effect modification in most subgroup analyses (p-interaction ≥ 0.05). In this cohort study of older women, accelerated biological aging measured by AgeAccelGrim2 was associated with higher risk of incident MCI/probable dementia. These findings provide evidence linking epigenetic biomarkers of biological aging with MCI and dementia development, independent of chronological age. Show less

Ambient air pollution exposures increase risk for Alzheimer's disease (AD) and related dementias, possibly due to structural changes in the medial temporal lobe (MTL). However, previous MRI studies examining exposure effects on the MTL were cross-sectional and mostly focused on the hippocampus, yielding mixed results. We addressed these limitations using longitudinal data collected from 653 cognitively unimpaired community-dwelling women from the Women's Health Initiative Memory Study with two MRI scans (M Show less

Apolipoprotein E (APOE) ε4 allele is the strongest genetic risk factor for late onset Alzheimer's disease (AD). This case-cohort study used targeted plasma biomarkers and large-scale proteomics to examine the biological mechanisms that allow some APOEε4 carriers to maintain normal cognitive functioning in older adulthood. APOEε4 carriers and APOEε3 homozygotes enrolled in the Women's Health Initiative Memory Study (WHIMS) from 1996 to 1999 were classified as resilient if they remained cognitively unimpaired beyond age 80, and as non-resilient if they developed cognitive impairment before or at age 80. AD pathology (Aß A total of 1610 participants were included (baseline age: 71.3 [3.8 SD] years; all White; 42% APOEε4 carriers). Compared to resilient APOEε4 carriers, non-resilient APOEε4 carriers had lower Aß We identified and replicated a plasma proteomic signature associated with cognitive resilience among APOEε4 carriers. These proteins implicate specific immune processes in the preservation of cognitive status despite elevated genetic risk for AD. Future studies in diverse cohorts will be needed to assess the generalizability of these results. Show less

Carbamylphosphate synthetase 1 (E.C. 6.3.4.16) deficiency is a rare autosomal recessive disorder of the urea cycle that can result in severe neonatal hyperammonemia. Since the genomic structure of the CPS1 gene was not yet elucidated, mutation detection was performed by analysis of transcripts in the past. Here, we present the entire DNA sequence of the human CPS1 gene including all exon-intron boundaries. Moreover, mutation analysis was performed in six patients leading to the detection of 9 novel mutations including the missense mutations c.2528T>C and c.2623A>G, the nonsense mutations c.712C>T and c.2115ins35bp, the splice site mutations c.1263+5G>C, c.3558+1G>C and c.4101+2T>C, and a small deletion c.3036₃₀₃₈delGGT. The mutations c.2528T>C and c.2623A>G were identified on a double mutated allele. New data on the genomic structure of the CPS1 gene provided in this study are useful to characterize the heterogenous molecular basis of the disease in patients deficient for carbamylphosphate 1 deficiency. Show less

Extracellular signal regulated kinase 5 (ERK5) is a novel member of the mitogen-activated protein kinase (MAPK) family with a poorly defined physiological function. Since ERK5 and its upstream activator MEK5 are abundant in skeletal muscle we examined a function of the cascade during muscle differentiation. We show that ERK5 is activated upon induction of differentiation in mouse myoblasts and that selective activation of the pathway results in promoter activation of differentiation-specific genes. Moreover, myogenic differentiation is completely blocked when ERK5 expression is inhibited by antisense RNA. Thus, we conclude that the MEK5/ERK5 MAP kinase cascade is critical for early steps of muscle cell differentiation. Show less