Objective: A new method was proposed to evaluate 'true' chewing efficiency in which the 'cost' of chewing was accounted for.
Design: Twenty-three subjects were asked to chew an almond for 5 cycles, after which the chewed particles were air-dried and passed through a 1.4-mm aperture sieve. The activity of both superficial masseter muscles was simultaneously recorded with surface EMG. Integrated EMG (IEMG) was used to calculate burst amplitude, burst duration and maximum voluntary contraction (MVC). The percentage weight of particles passing the sieve was used to represent the conventional chewing efficiency (or masticatory performance). Muscle work (integral of IEMG bursts), muscle effort (muscle work normalized to maximum work) and masticatory effectiveness (the ratio between masticatory performance and muscle work) were also calculated.
Results: The results showed that (1) masticatory performance was significantly correlated with muscle work (R=0.45; p<0.005), MVC (R=0.31; p=0.04), but not correlated with muscle effort; (2) masticatory effectiveness was significantly correlated with MVC (R=0.58, p<0.001), but not correlated with masticatory performance.
Conclusion: Persons with good masticatory performance were not necessarily effective (or efficient) chewers. They seemed to have larger MVCs and use more muscle work during the chewing task.
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http://dx.doi.org/10.1016/j.archoralbio.2007.12.014 | DOI Listing |
PLoS One
January 2025
Department of Human Kinetics, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada.
Demographic aging and extended working lives have prompted interest in the physiological changes that occur with age, particularly in the lumbar spine. Age-related declines in muscle quality and intervertebral disc alterations may reduce muscular endurance, strength, and postural stability, potentially increasing the risk of musculoskeletal injuries in older workers. As experienced workers play an important role in addressing labor shortages, understanding the impact of age-related physiological changes on the biomechanical properties of the lumbar spine is key to ensure safe and sustainable employment for aging individuals.
View Article and Find Full Text PDFCalcif Tissue Int
January 2025
School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai, People's Republic of China.
This study aims to identify novel loci associated with sarcopenia-related traits in UK Biobank (UKB) through multi-trait genome-wide analysis. To identify novel loci associated with sarcopenia, we integrated the genome-wide association studies (GWAS) of usual walking pace (UWP) and hand grip strength (HGS) to conduct a joint association study known as multi-trait analysis of GWAS (MTAG). We performed a transcriptome-wide association study (TWAS) to analyze the results of MTAG in relation to mRNA expression data for genes identified in skeletal muscle.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
Massachusetts Alzheimer's Disease Research Center, Charlestown, MA, USA.
Background: In cerebral amyloid angiopathy, amyloid beta accumulates within the walls of blood vessels and contributes to impaired vascular integrity and function. In this work, we observe that tau protein similarly builds up along blood vessels in Alzheimer's disease brain.
Method: We obtained frozen inferior temporal cortex from the Massachusetts Alzheimer's Disease Research Center from n = 7 neuropathological confirmed Alzheimer's disease donors and n = 6 normal aging controls.
Alzheimers Dement
December 2024
Alzheimer's Center at Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA.
Background: Alzheimer's disease (AD) is characterized- at both early and late stages- by neurovascular impairment. In AD, dysfunctional cerebral microvasculature is accompanied by an inflammatory response, contributing to Aβ and tau accumulation, brain cell stress and death, impaired clearance of metabolic waste, BBB permeability, and ultimately leading to neuronal demise and cognitive impairment. We previously showed that Aβ peptides induce mitochondrial dysregulation and caspase-mediated apoptosis in brain cells, including endothelial, glial, and smooth muscle cells.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
The Jackson Laboratory, Bar Harbor, ME, USA.
Background: Mechanisms driving cerebrovascular decline during Alzheimer's disease and related dementias (ADRD) are poorly understood. Methylenetetrahydrofolate reductase (MTHFR) is an enzyme in the folate/methionine pathway. Variants in MTHFR, notably 677C>T, are associated with ADRD.
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