MAG
Myelin-associated glycoprotein precursor (Siglec-4a) [GMA]
Publications[править]
Approximately, 600,000 people in South Korea have registered as people with either visual or hearing impairment or both. Individuals with sensory impairments are more likely to have limited physical and social functioning, which consequently affected their health, well-being and life satisfaction. While diverse elements were considered as critical determinants of life satisfaction among individuals with sensory impairments, only few studies examined the relationships between life domains and life satisfaction of the population. This study investigated the relationships between life domains and life satisfactions among Korean individuals with sensory impairments. This study used 2015 national data from Korea to explore the relationships across different age groups. A total of 965 participants were selected, and they were divided into three groups: (a) middle aged group (MAG; 54 and below, 35.2%), (b) late-middle aged group (L-MAG; 55-64; 35.2%), and (c) older adult group (OAG; 65 and older; 29.5%). Demographic variables (e.g., perceived socioeconomic status, the severity of disabilities), the satisfaction of seven life domains, and the overall life satisfaction were measured. Although most of the life domains were significant predictors of overall life satisfaction, the leisure domain was the strongest determinant of the overall life satisfaction to MAG and OAG and the second strongest predictor to L-MAG. This study highlights the importance of leisure for quality of life of individuals with sensory impairments and suggests an implication to researchers and practitioners to increase accessibility for individuals with sensory impairments to leisure facilities and programs.
Keywords
- Across the lifespan
- Leisure domain
- Life satisfaction
- Sensory impairment
- Social domain
During the last decade, essential polyunsaturated fatty acids (PUFAs) such as eicosatetraenoic acid (EPA) and docosahexaenoic acid (DHA) derived from marine sources have been investigated as nonpharmacological dietary supplements to improve different pathological conditions, as well as aging. The aim of this study was to determine the effects of dietary n-3 PUFA monoacylglycerides (MAG, both EPA and DHA) on the mitochondrial metabolism and oxidative stress of a short-lifespan model, [i]Drosophila melanogaster[/i], sampled at five different ages. Our results showed that diets supplemented with MAG-EPA and MAG-DHA increased median lifespan by 14.6% and decreased mitochondrial proton leak resulting in an increase of mitochondrial coupling. The flies fed on MAG-EPA also had higher electron transport system capacity and mitochondrial oxidative capacities. Moreover, both n-3 PUFAs delayed the occurrence of lipid peroxidation but only flies fed the MAG-EPA diet showed maintenance of superoxide dismutase activity during aging. Our study therefore highlights the potential of n-3 PUFA monoacylglycerides as nutraceutical compounds to delay the onset of senescence by acting directly or indirectly on the mitochondrial metabolism and suggests that Drosophila could be a relevant model for the study of the fundamental mechanisms linking the effects of n-3 PUFAs to aging.
MeSH Terms
- Animals
- Dietary Supplements
- Drosophila melanogaster
- Lipid Peroxidation
- Longevity
- Male
- Mitochondria
- Models, Animal
- Monoglycerides
- Oxidative Stress
Keywords
- aging
- mitochondrial metabolism
- monoacylglyceride
- oxidative stress
- polyunsaturated fatty acids
Sulfatides and gangliosides are raft-associated glycolipids essential for maintaining myelinated nerve integrity. Mice deficient in sulfatide (cerebroside sulfotransferase knock-out, [i]CST[/i] ) or complex gangliosides (β-1,4-[i]N[/i]-acetylegalactosaminyltransferase1 knock-out, [i]GalNAc-T[/i] ) display prominent disorganization of proteins at the node of Ranvier (NoR) in early life and age-dependent neurodegeneration. Loss of neuronal rather than glial complex gangliosides underpins the [i]GalNAc-T[/i] phenotype, as shown by neuron- or glial-specific rescue, whereas sulfatide is principally expressed and functional in glial membranes. The similarities in NoR phenotype of [i]CST[/i] , [i]GalNAc-T[/i] , and axo-glial protein-deficient mice suggests that these glycolipids stabilize membrane proteins including neurofascin155 (NF155) and myelin-associated glycoprotein (MAG) at axo-glial junctions. To assess the functional interactions between sulfatide and gangliosides, [i]CST[/i] and [i]GalNAc-T[/i] genotypes were interbred. [i]CST[/i] × [i]GalNAc-T[/i] mice develop normally to postnatal day 10 (P10), but all die between P20 and P25, coinciding with peak myelination. Ultrastructural, immunohistological, and biochemical analysis of either sex revealed widespread axonal degeneration and disruption to the axo-glial junction at the NoR. In addition to sulfatide-dependent loss of NF155, [i]CST[/i] × [i]GalNAc-T[/i] mice exhibited a major reduction in MAG protein levels in CNS myelin compared with WT and single-lipid-deficient mice. The [i]CST[/i] × [i]GalNAc-T[/i] phenotype was fully restored to that of [i]CST[/i] mice by neuron-specific expression of complex gangliosides, but not by their glial-specific expression nor by the global expression of [i]a[/i]-series gangliosides. These data indicate that sulfatide and complex [i]b[/i]-series gangliosides on the glial and neuronal membranes, respectively, act in concert to promote NF155 and MAG in maintaining the stable axo-glial interactions essential for normal nerve function. Sulfatides and complex gangliosides are membrane glycolipids with important roles in maintaining nervous system integrity. Node of Ranvier maintenance in particular requires stable compartmentalization of multiple membrane proteins. The axo-glial adhesion molecules neurofascin155 (NF155) and myelin-associated glycoprotein (MAG) require membrane microdomains containing either sulfatides or complex gangliosides to localize and function effectively. The cooperative roles of these microdomains and associated proteins are unknown. Here, we show vital interdependent roles for sulfatides and complex gangliosides because double (but not single) deficiency causes a rapidly lethal phenotype at an early age. These findings suggest that sulfatides and complex gangliosides on opposing axo-glial membranes are responsible for essential tethering of the axo-glial junction proteins NF155 and MAG, which interact to maintain the nodal complex.
MeSH Terms
- Animals
- Axons
- Cell Adhesion Molecules
- Female
- Gangliosides
- Genotype
- Life Expectancy
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Myelin Sheath
- Myelin-Associated Glycoprotein
- N-Acetylgalactosaminyltransferases
- Nerve Growth Factors
- Neuroglia
- Neurons
- Ranvier's Nodes
- Sulfoglycosphingolipids
- Sulfotransferases
Keywords
- MAG
- NF155
- axo–glial integrity
- ganglioside
- node of Ranvier
- sulfatide
Normal aging is characterized by decline in cognitive functioning in conjunction with extensive gray matter (GM) atrophy. A first aim of this study was to determine GM volume differences related to aging by comparing two groups of participants, middle-aged group (MAG, mean age 41 years, [i]N[/i] = 16) and older adults (OG, mean age 71 years, [i]N[/i] = 14) who underwent an magnetic resonance images (MRI) voxel-based morphometry (VBM) evaluation. The VBM analyses included two optimized pipelines, for the cortex and for the cerebellum. Participants were also evaluated on a wide range of cognitive tests assessing both domain-general and language-specific processes, in order to examine how GM volume differences between OG and MAG relate to cognitive performance. Our results show smaller bilateral GM volume in the OG relative to the MAG, in several cerebral and right cerebellar regions involved in language and executive functions. Importantly, our results also revealed smaller GM volume in the right cerebellum in OG relative to MAG, supporting the idea of a complex cognitive role for this structure. This study provides a broad picture of cerebral, but also cerebellar and cognitive changes associated with normal aging.
Keywords
- MRI
- VBM
- aging
- brain
- cognitive
- gray matter
Aging is dependent on biological processes that determine the aging of the organism at the cellular level. The Oxidative Stress Theory of Aging might explain some of the age-related changes in cell macromolecules. Moreover, exposome and lifestyle may also induce changes in cell damage induced by oxidative stress. The aim of the present study was to analyze the related redox changes in lymphocyte function of healthy women over 40 years old. Three groups: younger (YG: 40-49 years), middle aged (MAG: 50-59 years), and older (OG: ≥60 years) were evaluated on anthropometric variables, blood pressure, cardiovascular fitness, lifestyle habits, perceived stress, DNA damage, malondialdehyde, catalase activity, and total antioxidant capacity. Physical activity and cardiovascular fitness were significantly higher in YG and MAG as compared to the OG. Systolic blood pressure increased significantly with group age. Frequency and total amount of alcohol intake were lower in the OG and higher in the MAG. No significant differences were observed between the three groups in oxidative stress parameters. Only alcohol consumption was associated with the higher DNA FPG-sensitive sites, and only in the YG ([i]p[/i] < 0.05). Healthy lifestyle is critical to avoiding major ailments associated with aging. This may be inferred from the lack of significant differences in the various oxidative stress parameters measured in the healthy women over the age of 40 who took part in the study. Conscious lifestyle behaviors (decrease in alcohol and smoking habits) could have impaired the expected age-related oxidative stress increase.
Keywords
- DNA damage
- aging
- cardiovascular fitness
- lifestyle
- lipid peroxidation
- oxidative stress
The aim of this work was to study how age-related changes could modify several enzymatic activities that regulate lipid mediator levels in nuclei from rat cerebellum and how these changes are modulated by all-trans retinoic acid (RA), docosahexaenoic acid (DHA) and arachidonic acid (AA). The higher phosphatidate phosphohydrolase activity and lower diacylglycerol lipase (DAGL) activity observed in aged animals compared with adults could augment diacylglycerol (DAG) availability in the former. Additionally, monoacylglycerol (MAG) availability could be high due to an increase in lysophosphatidate phosphohydrolase (LPAPase) activity and a decrease in monocylglycerol lipase activity. Interestingly, RA, DHA and AA were observed to modulate these enzymatic activities and this modulation was found to change in aged rats. In adult nuclei, whereas RA led to high DAG and MAG production through inhibition of their hydrolytic enzymes, DHA and AA promoted high MAG production by LPAPase and DAGL stimulation. In contrast, in aged nuclei RA caused high MAG generation whereas DHA and AA diminished it through LPAPase activity modulation. These results demonstrate that aging promotes a different nuclear lipid metabolism as well as a different type of non-genomic regulation by RA, DHA and AA, which could be involved in nuclear signaling events.
MeSH Terms
- Aging
- Animals
- Arachidonic Acid
- Cell Nucleus
- Diglycerides
- Docosahexaenoic Acids
- Glycerophosphates
- Homeostasis
- Hydrolysis
- Lipase
- Lipid Metabolism
- Monoglycerides
- Rats
- Rats, Wistar
- Signal Transduction
- Tretinoin
Keywords
- Aging
- Diacylglycerol
- Docosahexaenoic acid
- Monoacylglycerol
- Nuclei
- Retinoic acid
Triacylglycerol (TAG) accumulates in plant seeds as a major renewable source of carbon for food, fuel and industrial feedstock. Approaches to enhance TAG content by altering lipid pathways and genes in vegetative parts have gained significant attention for biofuel and other applications. However, consequences of these modifications are not always studied in detail. In an attempt to increase TAG levels in leaves we previously demonstrated that a novel substrate, monoacylglycerol (MAG), can be used for the biosynthesis of diacylglycerol (DAG) and TAG. Transient expression of the Mus musculus monoacylglycerol acyltransferases MGAT1 and 2 in the model plant Nicotiana benthamiana increased TAG levels at 5 days post-infiltration (dpi). Here we show that increased TAG and DAG levels can be achieved as early as 2 dpi. In addition, the MGAT1 infiltrated areas showed senescence-like symptoms from 3 dpi onwards. To unravel underlying molecular mechanisms, Illumina deep sequencing was carried out (a) for de-novo assembling and annotation of N. benthamiana leaf transcripts and (b) to characterize MGAT1-responsive transcriptome. We found that MGAT1-responsive genes are involved in several processes including TAG biosynthesis, photosynthesis, cell-wall, cutin, suberin, wax and mucilage biosynthesis, lipid and hormone metabolism. Comparative analysis with transcript profiles from other senescence studies identified characteristic gene expression changes involved in senescence induction. We confirmed that increased TAG and observed senescence-symptoms are due to the MAG depletion caused by MGAT1 activity and suggest a mechanism for MGAT1 induced TAG increase and senescence-like symptoms. The data generated will serve as a valuable resource for oil and senescence related studies and for future N. benthamiana transcriptome studies.
Keywords
- Nicotiana benthamiana
- acyltransferase
- diacylglycerol
- differential gene expression
- monoacylglycerol
- oil increase
- senescence
- triacylglycerol
The aim of this study was to investigate the effects of the ageing process in the electromechanical delay (EMD), rate of torque development (RTD) and peak torque (PT) of the knee extensor muscles. The volunteers were assigned to three groups: young group (YG - 23·44 ± 4·74 years, 78·14 ± 15·11 kg, 1·72 ± 0·05 m), middle-aged group (MAG - 49·56 ± 6·06 years, 72·01 ± 14·07 kg, 1·67 ± 0·06 m) and elderly group (EG - 68·67 ± 9·06 years, 67·96 ± 7·60 kg, 1·64 ± 0·07 m). The PT and RTD were assessed during maximal voluntary ballistic isometric contractions (MVBIC) in the isokinetic dynamometer. Muscle electrical activity was recorded (EMG) during MVBIC in the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) muscles. The EMD was calculated during the MVBIC, through the time interval between the EMG onset and torque onset. The PT and RTD were higher in the YG than in the MAG (P = 0·02; P = 0·01, respectively) and in the EG (P = 0·002; P = 0·0004, respectively). There were no significant differences in EMD among the three age groups for the VL, VM and RF (P>0·05) muscles. We conclude that age affects the PT and RTD, but not EMD of the VL, VM and RF muscles.
MeSH Terms
- Adult
- Aged
- Aging
- Electromyography
- Excitation Contraction Coupling
- Female
- Humans
- Isometric Contraction
- Knee Joint
- Male
- Middle Aged
- Muscle, Skeletal
- Physical Endurance
- Reproducibility of Results
- Sensitivity and Specificity
- Torque
- Young Adult
Keywords
- ballistic
- elderly
- electromechanical delay
- peak torque
- rate of torque development