Association between Reduction of Muscle Mass and Faster Declines in Global Cognition among Older People: A 4-Year Prospective Cohort Study.

OBJECTIVES: A few studies reported that both decrease and increase in body mass index (BMI) were associated with the development of dementia in later life. However, it is unclear what changes in body composition are associated with cognitive decline. This study investigated the longitudinal influences of changes in body composition on cognitive function among community-dwelling adults. DESIGN, SETTING AND PARTICIPANTS: This longitudinal study included older adults aged ≥60 years without cognitive impairment who participated in National Institute for Longevity Sciences - Longitudinal Study of Aging. MEASUREMENTS: Cognitive function was assessed using the MMSE. Body composition was measured by a dual-energy X-ray absorptiometry system. Then, BMI, fat mass index (FMI), fat-free mass index (FFMI), and muscle mass index (MMI) were calculated. The changes in body composition over 6 years (second wave to fifth wave) were calculated, and three groups were created: decreased group, decrease of >5%; stable group, change within 5%, and increased group, increase of >5%. In statistical analysis, a linear mixed model was applied by sex to investigate the influences of body composition changes on cognitive function over 4 years (fifth wave to seventh wave). RESULTS: This study analyzed 515 participants (mean age, 67.05 years; 53.4% men). Men with decreased group in FFMI and MMI exhibited faster declines in MMSE scores than those with stable group (ß [95% CI]: FFMI, -0.293 [-0.719 to -0.020]; MMI, -0.472 [-0.884 to -0.059]). In women, there was no significant association between body composition changes and cognitive functions. CONCLUSIONS: Decrease in fat-free mass and muscle mass is associated with faster cognitive declines in men. These results suggest the importance of continuous monitoring of muscle mass to prevent cognitive decline in later life.

Cross-Sectional Associations of Sarcopenia and Its Components with Neuropsychological Performance among Memory Clinic Patients with Mild Cognitive Impairment and Alzheimer's Disease.

BACKGROUND: The association of sarcopenia with cognitive function in its specific domains remains poorly understood. OBJECTIVES: To investigate the association of sarcopenia and its components with neuropsychological performance among patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD). DESIGN: Cross-sectional design. SETTING: A memory clinic in Japan. PARTICIPANTS: The study included 497 MCI/684 AD patients aged 65-89 years. MEASUREMENTS: Patients were assessed for muscle mass by bioelectrical impedance analysis, muscle strength by hand grip strength (HGS), and physical performance by timed up and go test (TUG). Sarcopenia was defined as presence of both low muscle strength and low muscle mass. The patients underwent neuropsychological tests, including logical memory, frontal lobe assessment battery, word fluency test, Raven's colored progressive matrices, digit span, and the Alzheimer's disease assessment scale-cognitive subscale (ADAS-cog). RESULTS: The prevalence of sarcopenia in men and women was 24.1% and 19.5%, respectively. In multiple regression analyses adjusting for confounders, unlike in men, sarcopenia was associated with memory function in women (ADAS-cog, memory domain, coefficient = 1.08, standard error (SE) = 0.36), which was thought likely due to the relationship between HGS and memory function (immediate recall of logical memory, coefficient = 0.07, SE = 0.03; ADAS-cog, memory domain, coefficient = -0.10, SE = 0.03). Of the components of sarcopenia in both sexes, HGS and TUG were associated with visuospatial function and frontal lobe function, respectively. CONCLUSIONS: The specific association of sarcopenia and its components with cognitive domains may provide the key to elucidating the muscle-brain interactions in AD.

Impact of a Narrow Coastal Bay of Bengal Sea Surface Temperature Front on an Indian Summer Monsoon Simulation.

A dry bias in climatological Central Indian rainfall plagues Indian summer monsoon (ISM) simulations in multiple generations of climate models. Here, using observations and regional climate modeling, we focus on a warm coastal Bay of Bengal sea surface temperature (SST) front and its impact on Central Indian rainfall. The SST front, featuring sharp gradients as large as 0.5 °C/100 km, is colocated with a mixed layer depth (MLD) front, in a region where salinity variations are known to control MLD. Regional climate simulations coupling a regional atmospheric model with an ocean mixed layer model are performed. A simulation with observed MLD climatology reproduces SST, rainfall, and atmospheric circulation associated with ISM reasonably well; it also eliminates the dry bias over Central India significantly. Perturbing MLD structure in the simulations, we isolate the SST front's impact on the simulated ISM climate state. This experiment offers insights into ISM climatological biases in the coupled NCEP Climate Forecast System version-2. We suggest that the warm SST front is essential to Central Indian rainfall as it helps to sustain deep and intense convection in its vicinity, which may be a source for the vortex cores seeding the monsoon low-pressure systems.

A model for super El Niños.

Super El Niños, the strongest and most powerful of El Niños, impact economies, societies, and ecosystems disproportionately. Despite their importance, we do not fully understand how super El Niños develop their intensity and unique characteristics. Here, combining observational analyses with simple numerical simulations, we suggest that eastern Pacific intensified super El Niños result from the interaction of an El Niño and a positive Indian Ocean Dipole. Further, we identify a self-limiting behavior inherent to El Niño Southern Oscillation (ENSO) dynamics. This behavior-a consequence of the atmospheric Kelvin wave response that develops to the east of ENSO's convective anomalies-dampens sea surface temperature (SST) variations in the eastern Pacific, thereby preventing super El Niños from developing through tropical Pacific dynamics alone. Our model explains the features of the large 1972, 1982, and 1997 El Niños; the large SST anomalies during the 2015 El Niño, however, were likely enhanced by strong decadal variability.

Hadean geodynamics inferred from time-varying 142Nd/144Nd in the early Earth rock record.

Tracking the secular evolution of 142Nd/144Nd anomalies is important towards understanding the crust-mantle dynamics in the early Earth. Excessive scatter in the published data, however, precludes identifying the fine structure of 142Nd/144Nd evolution as the expected variability is on the order of few parts per million. We report ultra-high precision 142Nd/144Nd data for Eoarchean and Palaeoarchean rocks from the Isua Supracrustal Belt (SW Greenland) that show a well-resolved 142Nd/144Nd temporal variability suggesting progressive convective homogenisation of the Hadean Isua depleted mantle. This temporally decreasing 142Nd/144Nd signal provides a direct measure of early mantle dynamics, defining a stirring timescale of <250 Myr consistent with vigorous convective stirring in the early mantle. The 142Nd/144Nd evolution suggests protracted crustal residence times of ~1000-2000 Myr, inconsistent with modern-style plate tectonics in the Archean. In contrast, a stagnant-lid regime punctuated by episodes of mantle overturns accounts for the long life-time estimated here for the Hadean proto-crust.

Elevated glucose level adversely affects infarct volume growth and neurological deterioration in non-diabetic stroke patients, but not diabetic stroke patients.

BACKGROUND AND PURPOSE: Hyperglycemia is recognized as a common occurrence associated with a high risk of poor outcome in ischaemic stroke patients. However, little is known about the association between elevated glucose level, growth of infarct volume and neurological deterioration in ischaemic stroke patients without diabetes. The present study aimed to clarify this issue in acute ischaemic stroke patients with arterial occlusion. METHODS: We studied 375 acute ischaemic stroke patients with arterial occlusion within 24 h of onset. Diabetes was diagnosed in patients with a known history of diabetes or HbA1c value ≥ 6.5%. Infarct volume was measured on admission and at follow-up within 48 h using diffusion-weighted imaging. Neurological deterioration was defined as an increase of ≥ 4 points in National Institutes of Health Stroke Scale score within 7 days of stroke onset. We examined the relationship between glucose level on admission, infarct volume growth and neurological deterioration in three categories (all patients, non-diabetes and diabetes) using multivariate modeling. RESULTS: Diabetes was present in 104 patients (27.7%). Multivariate regression analysis showed that elevated glucose level was independently associated with infarct volume growth in all patients (P = 0.034) and non-diabetes (P = 0.002), but not in diabetes (P = 0.871). Moreover, elevated glucose level was independently associated with neurological deterioration in all patients [odds ratio (OR), 1.010; 95% confidence interval (CI), 1.004-1.017; P = 0.002] and non-diabetes (OR, 1.014; 95% CI, 1.002-1.026; P = 0.022), but not diabetes (OR, 1.006; 95% CI, 0.998-1.014; P = 0.151). CONCLUSIONS: Glucose level appears to influence infarct volume growth and neurological deterioration, particularly in non-diabetic patients with ischaemic stroke.

A dipole mode in the tropical Indian Ocean.

For the tropical Pacific and Atlantic oceans, internal modes of variability that lead to climatic oscillations have been recognized, but in the Indian Ocean region a similar ocean-atmosphere interaction causing interannual climate variability has not yet been found. Here we report an analysis of observational data over the past 40 years, showing a dipole mode in the Indian Ocean: a pattern of internal variability with anomalously low sea surface temperatures off Sumatra and high sea surface temperatures in the western Indian Ocean, with accompanying wind and precipitation anomalies. The spatio-temporal links between sea surface temperatures and winds reveal a strong coupling through the precipitation field and ocean dynamics. This air-sea interaction process is unique and inherent in the Indian Ocean, and is shown to be independent of the El Niño/Southern Oscillation. The discovery of this dipole mode that accounts for about 12% of the sea surface temperature variability in the Indian Ocean--and, in its active years, also causes severe rainfall in eastern Africa and droughts in Indonesia--brightens the prospects for a long-term forecast of rainfall anomalies in the affected countries.

Purified protein kinase C phosphorylates microtubule-associated protein 2.

We have investigated actions of purified protein kinase C on microtubule- and microfilament-related proteins. Among the cytoskeletal proteins examined, microtubule-associated protein 2 (MAP2) was found to serve as a good substrate. Other cytoskeletal proteins, tubulin, fodrin, cofilin, tropomyosin, and 53,000-Da protein, were very poorly phosphorylated. The amino acid residues of MAP2 that were phosphorylated by the protein kinase C were almost exclusively serine. The peptide mapping analysis indicated that protein kinase C and cAMP-dependent protein kinase phosphorylate MAP2 differently. The ability of MAP2 to interact with actin was markedly reduced by this protein kinase C-mediated phosphorylation. These data raise the possibility that phosphorylation of MAP2 by activated protein kinase C may be involved in cell-surface signal transduction.