Effect of Dietary Patterns on Muscle Strength and Physical Performance in the Very Old: Findings from the Newcastle 85+ Study

Background

Healthy diet has been associated with better muscle strength and physical performance in cross-sectional studies of older adults but the effect of dietary patterns (DP) on subsequent decline, particularly in the very old (aged 85+), has not been determined.

Objective

We investigated the association between previously established DP and decline in muscle strength and physical performance in the very old.

Design

791 participants (61.8% women) from the Newcastle 85+ Study were followed-up for change in hand grip strength (HGS) and Timed Up-and Go (TUG) test over 5 years (four waves 1.5 years apart). Mixed models were used to determine the effects of DP on muscle strength and physical performance in the entire cohort and separately by sex.

Results

Previously we have established three DP that varied in intake of red meats, potato, gravy and butter and differed with key health and social factors. HGS declined linearly by 1.59 kg_F in men and 1.08 kg_F in women (both p<0.001), and TUG slowed by 0.13 log₁₀-transformed seconds (log₁₀-s) in men and 0.11 log₁₀-s in women per wave after adjusting for important covariates (both p<0.001), and also showed a nonlinear change (p<0.001). Men in DP1 (‘High Red Meat’) had worse overall HGS (β = -1.70, p = 0.05), but men in DP3 (‘High Butter’) had a steeper decline (β = -0.63, p = 0.05) than men in DP2 (‘Low Meat’). Men in DP1 and women in DP3 also had overall slower TUG than those in DP2 (β = 0.08, p = 0.001 and β = 0.06, p = 0.01, respectively), but similar rate of decline after adjusting for sociodemographic, lifestyle, health, and functioning factors. The results for HGS and TUG were not affected by participants’ cognitive status.

Conclusions

DP high in red meats, potato and gravy (DP1), or butter (DP3) may adversely affect muscle strength and physical performance in later life, independently of important covariates and cognitive status.     

Mitotic Spindle Defects and Chromosome Mis-Segregation Induced by LDL/Cholesterol—Implications for Niemann-Pick C1, Alzheimer’s Disease,and Atherosclerosis

Elevated low-density lipoprotein (LDL)-cholesterol is a risk factor for both Alzheimer’s disease (AD) and Atherosclerosis (CVD), suggesting a common lipid-sensitive step in their pathogenesis. Previous results show that AD and CVD also share a cell cycle defect: chromosome instability and up to 30% aneuploidy–in neurons and other cells in AD and in smooth muscle cells in atherosclerotic plaques in CVD. Indeed, specific degeneration of aneuploid neurons accounts for 90% of neuronal loss in AD brain, indicating that aneuploidy underlies AD neurodegeneration. Cell/mouse models of AD develop similar aneuploidy through amyloid-beta (Aß) inhibition of specific microtubule motors and consequent disruption of mitotic spindles. Here we tested the hypothesis that, like upregulated Aß, elevated LDL/cholesterol and altered intracellular cholesterol homeostasis also causes chromosomal instability. Specifically we found that: 1) high dietary cholesterol induces aneuploidy in mice, satisfying the hypothesis’ first prediction, 2) Niemann-Pick C1 patients accumulate aneuploid fibroblasts, neurons, and glia, demonstrating a similar aneugenic effect of intracellular cholesterol accumulation in humans 3) oxidized LDL, LDL, and cholesterol, but not high-density lipoprotein (HDL), induce chromosome mis-segregation and aneuploidy in cultured cells, including neuronal precursors, indicating that LDL/cholesterol directly affects the cell cycle, 4) LDL-induced aneuploidy requires the LDL receptor, but not Aß, showing that LDL works differently than Aß, with the same end result, 5) cholesterol treatment disrupts the structure of the mitotic spindle, providing a cell biological mechanism for its aneugenic activity, and 6) ethanol or calcium chelation attenuates lipoprotein-induced chromosome mis-segregation, providing molecular insights into cholesterol’s aneugenic mechanism, specifically through its rigidifying effect on the cell membrane, and potentially explaining why ethanol consumption reduces the risk of developing atherosclerosis or AD. These results suggest a novel, cell cycle mechanism by which aberrant cholesterol homeostasis promotes neurodegeneration and atherosclerosis by disrupting chromosome segregation and potentially other aspects of microtubule physiology.     

Functional characterization of selected LEA proteins from Arabidopsis thaliana in yeast and in vitro

Main conclusion

Expression of eight LEA genes enhanced desiccation tolerance in yeast, including two LEA_2 genes encoding atypical, stably folded proteins. The recombinant proteins showed enzyme, but not membrane protection during drying. To screen for possible functions of late embryogenesis abundant (LEA) proteins in cellular stress tolerance, 15 candidate genes from six Arabidopsis thaliana LEA protein families were expressed in Saccharomyces cerevisiae as a genetically amenable eukaryotic model organism. Desiccation stress experiments showed that eight of the 15 LEA proteins significantly enhanced yeast survival. While none of the proteins belonging to the LEA_1, LEA_5 or AtM families provided protection to yeast cells, two of three LEA_2 proteins, all three LEA_4 proteins and three of four dehydrins were effective. However, no significantly enhanced tolerance toward freezing, salt, osmotic or oxidative stress was observed. While most LEA proteins are highly hydrophilic and intrinsically disordered, LEA_2 proteins are “atypical”, since they are more hydrophobic and possess a stable folded structure in solution. Because nothing was known about the functional properties of LEA_2 proteins, we expressed the three Arabidopsis proteins LEA1, LEA26 and LEA27 in Escherichia coli. The bacteria expressed all three proteins in inclusion bodies from which they could be purified and refolded. Correct folding was ascertained by Fourier transform Infrared (FTIR) spectroscopy. None of the proteins was able to stabilize liposomes during freezing or drying, but they were all able to protect the enzyme lactate dehydrogenase (LDH) from inactivation during freezing. Significantly, only LEA1 and LEA27, which also protected yeast cells during drying, were able to stabilize LDH during desiccation and subsequent rehydration.     

Lentiviral-mediated over-expression of hyaluronan synthase-1 (HAS-1) decreases the cellular inflammatory response and results in regenerative wound repair

Fetal wounds have been found to have increased levels of high-molecular-weight hyaluronan (HMW-HA) compared with those of adults. The primary enzyme responsible for producing HMW-HA is hyaluronic acid synthase-1 (HAS-1). We hypothesized that over-expression of HAS-1 in adult dermal wounds would decrease inflammation and promote regenerative healing. To test this hypothesis, the flanks of adult C57Bl/6 mice were treated with a lentiviral construct containing either HAS-1-GFP or GFP transgenes. After 48 h, a 4-mm excisional wound was made at the site of treatment. Wounds were harvested at days 3, 7, or 28 after wounding. Wound phenotype was assessed by histology to examine tissue architecture and immunohistochemistry for CD45. At 7 and 28 days, lenti-HAS-1-treated wounds demonstrated the restoration of the normal dermal elements and organized collagen fiber orientation. In contrast, the lenti-GFP-treated wounds lacked normal dermal architecture and demonstrated a disorganized collagen scar. At 3 and 7 days, wounds treated with lenti-HAS-1 exhibited a significant decrease in the number of inflammatory cells when compared with wounds treated with lenti-GFP. Thus, HAS-1 over-expression promotes dermal regeneration, in part by decreasing the inflammatory response and by recapitulation of fetal extracellular matrix HMW-HA content.     

Alzheimer Aβ Peptide Induces Chromosome Mis-Segregation and Aneuploidy,Including Trisomy 21: Requirement for Tau and APP

Both sporadic and familial Alzheimer''s disease (AD) patients exhibit increased chromosome aneuploidy, particularly trisomy 21, in neurons and other cells. Significantly, trisomy 21/Down syndrome patients develop early onset AD pathology. We investigated the mechanism underlying mosaic chromosome aneuploidy in AD and report that FAD mutations in the Alzheimer Amyloid Precursor Protein gene, APP, induce chromosome mis-segregation and aneuploidy in transgenic mice and in transfected cells. Furthermore, adding synthetic Aβ peptide, the pathogenic product of APP, to cultured cells causes rapid and robust chromosome mis-segregation leading to aneuploid, including trisomy 21, daughters, which is prevented by LiCl addition or Ca²⁺ chelation and is replicated in tau KO cells, implicating GSK-3β, calpain, and Tau-dependent microtubule transport in the aneugenic activity of Aβ. Furthermore, APP KO cells are resistant to the aneugenic activity of Aβ, as they have been shown previously to be resistant to Aβ-induced tau phosphorylation and cell toxicity. These results indicate that Aβ-induced microtubule dysfunction leads to aneuploid neurons and may thereby contribute to the pathogenesis of AD.     

Dietary Patterns and Socioeconomic Status in the Very Old: The Newcastle 85+ Study

BackgroundDietary patterns (DP) are associated with health outcomes in younger adults but there is a lack of evidence in the very old (aged 85+) on DP and their association with sociodemographic factors, lifestyle, health and functioning measures. Higher socioeconomic status (SES) has been linked with healthier DP but it is not known whether these associations are sustained in the very old.ObjectiveWe aimed to (a) characterise DP in the very old and (b) assess the relationships between three SES indicators (education, occupational class and area-deprivation index [IMD]) and DP.MethodsComplete dietary data at baseline (2006/07) for 793 participants in the Newcastle 85+ Study were established through 24-hr multiple pass recall. We used Two-Step clustering and 30 food groups to derive DP, and multinomial logistic regression models to assess the association with SES.ResultsWe identified three distinct DP (characterised as ‘High Red Meat’, ‘Low Meat’, and ‘High Butter’) that varied with key sociodemographic, health and functioning measures. ‘Low Meat’ participants were more advantaged (i.e. higher education and occupational class, and lived in more affluent areas in owned homes), were least disabled, cognitively impaired, and depressed, and were more physically active than those in the other DP. After adjusting for other lifestyle factors, cognitive status and BMI, lower educational attainment remained a significant predictor of ‘High Red Meat’ and ‘High Butter’ membership compared with ‘Low Meat’ (‘High Red Meat’: OR [95% CI] for 0–9 and 10–11 years of education vs. ≥12 years: 5.28 [2.85–9.79], p<0.001 and 3.27 [1.65–6.51], p = 0.001, respectively; ‘High Butter’: 3.32 [1.89–5.82], p<0.001 and 2.83 [1.52–5.28], p = 0.001).ConclusionsIn this cohort of very old adults, we detected a favourable DP (‘Low Meat’), which was associated with better health and functioning and higher SES.     

Transduction of satellite cells after prenatal intramuscular administration of lentiviral vectors

BACKGROUND: We have previously reported long-term expression of lacZ in myocytes after in utero intramuscular injection of Mokola and Ebola pseudotyped lentiviral vectors. In further experiments, we have noted that these vectors also transduce small cells at the periphery of the muscle fibers that have the morphology of satellite cells, or muscle stem cells. In this study we performed experiments to further define the morphology and function of these cells. METHODS: Balb/c mice at 14-15 days gestation were injected intramuscularly with Ebola or Mokola pseudotyped lentiviral vectors carrying CMV-lacZ. Animals were harvested at various time points, muscles were stained with X-gal, and processed for electron microscopy (EM) and immunofluorescence. To determine whether transduced satellite cells were functionally capable of regenerating injured muscles, animals were injected with notexin in the same area 8 weeks after the in utero injection of viral vector. RESULTS: Transmission EM of transduced cells confirmed the ultrastructural appearance of satellite cells. Double immunofluorescence for beta-galactosidase and satellite cell markers demonstrated co-localization of these markers in transduced cells. In the notexin-injured animals, small blue cells were seen at the areas of regeneration that co-localized beta-galactosidase with markers of regenerating satellite cells. Central nucleated blue fibers were seen at late time points, indicating regenerated muscle fibers arising from a transduced satellite cell. CONCLUSIONS: This study demonstrates transduction of muscle satellite cells following prenatal viral vector mediated gene transfer. These findings may have important implications for gene therapy strategies directed toward muscular dystrophy.     

Alzheimer Aβ disrupts the mitotic spindle and directly inhibits mitotic microtubule motors

Chromosome mis-segregation and aneuploidy are greatly induced in Alzheimer disease and models thereof by mutant forms of the APP and PS proteins and by their product, the Aβ peptide. Here we employ human somatic cells and Xenopus egg extracts to show that Aβ impairs the assembly and maintenance of the mitotic spindle. Mechanistically, these defects result from Aβ''s inhibition of mitotic motor kinesins, including Eg5, KIF4A and MCAK. In vitro studies show that oligomeric Aβ directly inhibits recombinant MCAK by a noncompetitive mechanism. In contrast, inhibition of Eg5 and KIF4A is competitive with respect to both ATP and microtubules, indicating that Aβ interferes with their interactions with the microtubules of the mitotic spindle. Consistently, increased levels of polymerized microtubules or of the microtubule stabilizing protein Tau significantly decrease the inhibitory effect of Aβ on Eg5 and KIF4A. Together, these results indicate that by disrupting the interaction between specific kinesins and microtubules and by exerting a direct inhibitory effect on the motor activity, excess Aβ deregulates the mechanical forces that govern the spindle and thereby leads to the generation of defective mitotic structures. The resulting defect in neurogenesis can account for the over 30% aneuploid/hyperploid, degeneration-prone neurons observed in Alzheimer disease brain. The finding of mitotic motors including Eg5 in mature post-mitotic neurons implies that their inhibition by Aβ may also disrupt neuronal function and plasticity.Key words: aneuploidy, Alzheimer disease, Eg5, KIF4A, MCAK, amyloid