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1.
Dysphagia ; 38(5): 1430-1439, 2023 10.
Article in English | MEDLINE | ID: mdl-37106228

ABSTRACT

Swallowing function can deteriorate with age, leading to a risk of dysphagia. Swallowing evaluation by surface electromyography (sEMG) can be easily and extensively applied for an elderly population. This study evaluated the temporal events observed by sEMG to clarify how aging affects the coordination among the masticatory and suprahyoid muscles. We recruited elderly individuals (over 65 years old) who denied dysphagia. The sEMG activities of anterior temporalis, masseter, and suprahyoid muscles were recorded during 3, 15, and 30 ml water swallowing tests (WST). We calculated the time interval between anterior temporalis and suprahyoid peak activity (T-SH interval) and masseter and suprahyoid peak activity (M-SH interval) and analyzed their correlation with age. The subjects who could and could not swallow 30 ml of water in one gulp were further assigned into the one-gulp and piecemeal groups, respectively, for subgroup analysis. We recruited 101 subjects, among whom 75 (26 males and 49 females) were analyzed after excluding those with suspected dysphagia or low-quality sEMG recordings. Age was significantly correlated with the bilateral T-SH (left: r = 0.249, p = 0.031; right: r = 0.412, p < 0.01) and right M-SH (r = 0.242, p = 0.037) intervals in the 30 ml WST. The correlation between intervals and age were observed in both subgroups. sEMG can be used to investigate the effect of aging on the temporal coordination between masticatory and suprahyoid contraction. Further studies are needed to verify the validity of screening subclinical dysphagia in the elderly.


Subject(s)
Deglutition Disorders , Deglutition , Male , Female , Humans , Aged , Electromyography , Deglutition/physiology , Deglutition Disorders/diagnosis , Neck Muscles/physiology , Aging
2.
Polymers (Basel) ; 15(6)2023 Mar 15.
Article in English | MEDLINE | ID: mdl-36987242

ABSTRACT

The high theoretical charge-storage capacity and energy density of lithium-sulfur batteries make them a promising next-generation energy-storage system. However, liquid polysulfides are highly soluble in the electrolytes used in lithium-sulfur batteries, which results in irreversible loss of their active materials and rapid capacity degradation. In this study, we adopt the widely applied electrospinning method to fabricate an electrospun polyacrylonitrile film containing non-nanoporous fibers bearing continuous electrolyte tunnels and demonstrate that this serves as an effective separator in lithium-sulfur batteries. This polyacrylonitrile film exhibits high mechanical strength and supports a stable lithium stripping and plating reaction that persists for 1000 h, thereby protecting a lithium-metal electrode. The polyacrylonitrile film also enables a polysulfide cathode to attain high sulfur loadings (4-16 mg cm-2) and superior performance from C/20 to 1C with a long cycle life (200 cycles). The high reaction capability and stability of the polysulfide cathode result from the high polysulfide retention and smooth lithium-ion diffusion of the polyacrylonitrile film, which endows the lithium-sulfur cells with high areal capacities (7.0-8.6 mA·h cm-2) and energy densities (14.7-18.1 mW·h cm-2).

3.
Sci Rep ; 11(1): 8899, 2021 04 26.
Article in English | MEDLINE | ID: mdl-33903664

ABSTRACT

Patients with Lynch syndrome have a high risk of colorectal cancer (CRC). In this study, we estimated the age- and sex-specific cumulative risks of CRC in Han Chinese patients with Lynch syndrome caused by the pathogenic germline mutations in MLH1 or MSH2 in Taiwan. Based on 321 mutation carriers and 419 non-mutation carriers from 75 pedigrees collected in an Amsterdam criteria family registry in Taiwan, the age- and sex-specific cumulative risks of CRC in male carriers of mutation in MLH1 and MSH2 at the age of 70 years were 60.3% (95% confidence interval (CI) = 31.1%-89.9%) and 76.7% (95% CI = 37.2%-99.0%), respectively. For females, the cumulative risks of CRC at the age of 70 were estimated to be 30.6% (95% CI = 14.3%-57.7%) and 49.3% (95% CI = 21.9%-84.5%) in the carriers of MLH1 and MSH2 germline mutations, respectively. In conclusion, the cumulative risks of CRC at the age of 70 in the Han Chinese patients is higher in mutation carriers than non-mutation carriers and male mutation carriers have a higher cumulative risk of developing CRC than the female mutation carriers.


Subject(s)
Colorectal Neoplasms, Hereditary Nonpolyposis/genetics , Germ-Line Mutation , MutL Proteins/genetics , MutS Homolog 2 Protein/genetics , Neoplasm Proteins/genetics , Adult , Age Factors , Aged , Asian People , Colorectal Neoplasms, Hereditary Nonpolyposis/ethnology , Female , Humans , Male , Middle Aged , Risk Factors , Taiwan
4.
Polymers (Basel) ; 13(4)2021 Feb 11.
Article in English | MEDLINE | ID: mdl-33670405

ABSTRACT

In lithium-sulfur cells, the dissolution and relocation of the liquid-state active material (polysulfides) lead to fast capacity fading and low Coulombic efficiency, resulting in poor long-term electrochemical stability. To solve this problem, we synthesize a composite using a gel polymer electrolyte and a separator as a functional membrane, coated with a layer of poly(ethylene oxide) (PEO) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The PEO/LiTFSI-coated polypropylene membrane slows the diffusion of polysulfides and stabilizes the liquid-state active material within the cathode region of the cell, while allowing smooth lithium-ion transfer. The lithium-sulfur cells with the developed membrane demonstrate a high charge-storage capacity of 1212 mA∙h g-1, 981 mA∙h g-1, and 637 mA∙h g-1 at high sulfur loadings of 2 mg cm-2, 4 mg cm-2, and 6 mg cm-2, respectively, and maintains a high reversible capacity of 534 mA∙h g-1 after 200 cycles, proving its ability to block the irreversible diffusion of polysulfides and to maintain the stabilized polysulfides as the catholyte for improved electrochemical utilization and stability. As a comparison, reference and control cells fabricated using a PEO-coated polypropylene membrane and a regular separator, respectively, show a poor capacity of 662 mA∙h g-1 and a short cycle life of 50 cycles.

5.
Anticancer Res ; 38(10): 5983-5990, 2018 Oct.
Article in English | MEDLINE | ID: mdl-30275229

ABSTRACT

BACKGROUND/AIM: Epidermal growth factor receptor (EGFR), mothers against decapentaplegic homolog 7 (SMAD7) and transforming growth factor betta (TGFB) are crucial for colorectal cancer (CRC) tumorigenesis. This study investigated whether polymorphisms in EGFR, SMAD7, and TGFB are associated with CRC risk in patients with Lynch syndrome. MATERIALS AND METHODS: Genotyping was performed using Sequenom iPLEX MassArray. Association between genetic polymorphisms and CRC was assessed using a weighted Cox proportional hazard model. RESULTS: Patients carrying the AA genotype of EGFR rs2227983 had a significantly higher CRC risk than those carrying the G allele (HR=2.55, 95% CI=1.25-5.17). The dominant model of SMAD7 rs12953717 (CT + TT genotypes) significantly increased CRC risk (HR=2.17, 95% CI=1.12-4.16) when compared to the wild-type CC genotype. Similarly, the GG genotype of TGFBR2 rs6785358 significantly increased the risk of CRC (HR=21.1, 95% CI=5.06-88.1) compared to the AA genotype. CONCLUSION: EGFR, SMAD7, and TGFBR2 are associated with CRC risk in patients with Lynch syndrome.


Subject(s)
Biomarkers, Tumor/genetics , Colorectal Neoplasms, Hereditary Nonpolyposis/genetics , Colorectal Neoplasms/genetics , ErbB Receptors/genetics , Polymorphism, Single Nucleotide , Protein Serine-Threonine Kinases/genetics , Receptors, Transforming Growth Factor beta/genetics , Smad7 Protein/genetics , Colorectal Neoplasms/complications , Colorectal Neoplasms/pathology , Colorectal Neoplasms, Hereditary Nonpolyposis/complications , Colorectal Neoplasms, Hereditary Nonpolyposis/pathology , Genetic Predisposition to Disease , Genotype , Humans , Prognosis , Receptor, Transforming Growth Factor-beta Type II
6.
Article in English | MEDLINE | ID: mdl-29664240

ABSTRACT

BACKGROUND: DNA repair genes are crucial for maintaining genomic stability by preventing mutagenesis and carcinogenesis. The present retrospective cohort study aimed at investigating whether MLH1, APEX1, MUTYH, OGG1, NUDT1, XRCC5, XPA, and ERCC2 single nucleotide polymorphisms (SNPs) are associated with colorectal cancer (CRC) in Chinese population with Lynch syndrome. METHODS: From Amsterdam criteria family registry, we identified 270 patients with Lynch syndrome. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between DNA repair SNPs and CRC were calculated using a weighted Cox proportional hazard regression model. RESULTS: Heterozygous variants of rs1799832 in NUDT1 (HR = 2.97, 95% CI = 1.51-5.83) and rs13181 in ERCC2 (HR = 2.69, 95% CI = 1.10-6.55) were significantly associated with an increased risk of CRC compared with wild-type homozygous CC and TT genotypes, respectively. However, the variant CG+GG genotype of MUTYH rs3219489 was associated with a decreased risk of CRC (HR = 0.49, 95% CI = 0.26-0.91) compared with the homozygous CC wild-type counterparts. CONCLUSION: Our findings revealed that polymorphisms of DNA repair genes that include NUDT1, ERCC2, and MUTYH are associated with CRC in patients with Lynch syndrome in Chinese population. Further studies with large sample size are needed to confirm our findings.

7.
Environ Mol Mutagen ; 59(1): 69-78, 2018 01.
Article in English | MEDLINE | ID: mdl-28714190

ABSTRACT

Cytochrome P450 (CYP), glutathione-S-transferase (GST), and N-acetyltransferase (NAT) are crucial for metabolism and clearance of xenobiotics. This study investigated whether CYP, GST, and NAT single nucleotide polymorphisms (SNPs) are associated with colorectal cancer (CRC) in patients with Lynch syndrome. The interaction between these SNPs and cigarette smoking or meat consumption was also explored. We identified 270 patients with Lynch syndrome from the Taiwan Hereditary Nonpolyposis Colorectal Cancer Consortium. A weighted Cox proportional hazard model was used to calculate the hazard ratios (HRs) and 95% confidence interval (CIs). The GSTA1 rs3957356 TT (HR = 5.36, 95% CI = 2.39-12.0) and CYP1B1 rs1056836 CC (HR = 7.24, 95% CI = 3.51-14.9) were significantly associated with CRC risk when compared to wild-type CC and GG genotypes, respectively. However, the CYP1A1 rs4646903 CC genotype significantly reduced the risk of CRC (HR = 0.33, 95% CI = 0.12-0.89) when compared to TT genotype. Moreover, significant interactions were observed between NAT1 acetylation and CYP1B1 rs1056827 and meat consumption.Our results suggest that xenobiotic-metabolizing SNPs are not only associated with CRC risk in patients with Lynch syndrome in Taiwan but also interact with meat consumption to modify the disease risk. Environ. Mol. Mutagen. 59:69-78, 2018. © 2017 Wiley Periodicals, Inc.


Subject(s)
Colorectal Neoplasms, Hereditary Nonpolyposis/genetics , Colorectal Neoplasms/genetics , Genetic Predisposition to Disease/genetics , Polymorphism, Single Nucleotide/genetics , Xenobiotics/metabolism , Adult , Female , Genotype , Humans , Male , Middle Aged , Retrospective Studies , Risk , Taiwan , Young Adult
8.
Percept Mot Skills ; 124(2): 477-490, 2017 Apr.
Article in English | MEDLINE | ID: mdl-28361659

ABSTRACT

We compared responses from postmenopausal women living a sedentary lifestyle ( n = 15; Mean age= 59; SD = 4.2) to a single bout of water- or land-based exercise with respect to ratings of perceived exertion (RPE), lactate concentration, and muscle oxygen saturation. Each participant was randomly assigned to a single water- or land-based 50-minute bout of combined aerobic and resistance exercise. Blood samples were collected to detect pre- and post-exercise lactate concentration. Total hemoglobin, deoxidized hemoglobin, and the percentage change in the total oxygen saturation index (TSI%) of the rectus femoris were detected by means of near-infrared spectroscopy. We found similar RPE at various stages of land- and water-based exercise, and a similar change in lactate concentration in these environments (in water: 4.35 ± 1.49 mol/L; on land: 3.62 ± 1.18 mol/L). However, the reduction in HHb response was less pronounced after water-based exercise, and TSI% increased on land but decreased in water, with the magnitude of this change much higher on land. For similar RPE and lactate concentration, the oxygen saturation in the exercising muscles decreased in water, suggesting higher oxygen consumption in water than on land.


Subject(s)
Exercise/physiology , Physical Exertion/physiology , Postmenopause/physiology , Quadriceps Muscle/metabolism , Sedentary Behavior , Female , Humans , Lactic Acid/blood , Middle Aged , Oxygen Consumption/physiology , Postmenopause/blood , Postmenopause/metabolism , Spectroscopy, Near-Infrared
9.
PLoS One ; 11(12): e0167354, 2016.
Article in English | MEDLINE | ID: mdl-27907203

ABSTRACT

BACKGROUND AND AIM: TP53 encodes p53, which has a crucial role in modulating genes that regulate defense against cancer development. This study investigated whether TP53 polymorphisms are associated with colorectal cancer (CRC) in patients with Lynch syndrome and whether TP53 interacts with lifestyle factors to modify CRC risk. METHODS: We identified 260 MLH1 and MSH2 germline mutation carriers from the Taiwan Hereditary Nonpolyposis Colorectal Cancer Consortium. A weighted Cox proportional hazard model was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) to determine the association of TP53 polymorphisms with CRC development. RESULTS: The carriers of the variant C allele of rs1042522 were associated with a decreased CRC risk (GC genotype: HR = 0.35, 95% CI = 0.14-0.86; CC genotype: HR = 0.28, 95% CI = 0.13-0.57). In addition, the dominant model of rs1042522 was associated with a decreased CRC risk (HR = 0.32, 95% CI = 0.15-0.67). The CRC risk was decreased in carriers with the CT and TT genotypes of rs12947788 (HR = 0.20, 95% CI = 0.08-0.46 and HR = 0.25, 95% CI = 0.09-0.65, respectively). Moreover, the dominant model of rs12947788 was significantly associated with a decreased CRC risk (HR = 0.21, 95% CI = 0.09-0.46). A haplotype analysis indicated that compared with the most common GC haplotype, the CT haplotype was associated with a decreased CRC risk (HR = 0.26, 95% CI = 0.11-0.59). However, no significant interaction was observed between TP53 polymorphisms and lifestyle factors. CONCLUSION: The study results revealed that the rs1042522 genotype with the C allele and the rs12947788 genotype with the T allele in TP53 were associated with a decreased CRC risk in patients with Lynch syndrome in Taiwan.


Subject(s)
Colorectal Neoplasms, Hereditary Nonpolyposis/genetics , Colorectal Neoplasms/genetics , Genetic Predisposition to Disease , Tumor Suppressor Protein p53/genetics , Adult , Colorectal Neoplasms/complications , Colorectal Neoplasms/pathology , Colorectal Neoplasms, Hereditary Nonpolyposis/complications , Colorectal Neoplasms, Hereditary Nonpolyposis/pathology , Female , Genetic Association Studies , Genotype , Germ-Line Mutation , Haplotypes , Humans , Male , Middle Aged , MutL Protein Homolog 1/genetics , MutS Homolog 2 Protein/genetics , Polymorphism, Single Nucleotide/genetics , Retrospective Studies , Risk Factors , Taiwan
10.
PLoS One ; 10(6): e0130018, 2015.
Article in English | MEDLINE | ID: mdl-26053027

ABSTRACT

BACKGROUND AND AIM: Lynch syndrome, caused by germline mutations in mismatch repair genes, is a predisposing factor for colorectal cancer (CRC). This retrospective cohort study investigated the risk factors associated with the development of CRC in patients with MLH1 and MSH2 germline mutations. METHODS: In total, 301 MLH1 and MSH2 germline mutation carriers were identified from the Amsterdam criteria family registry provided by the Taiwan Hereditary Nonpolyposis Colorectal Cancer Consortium. A Cox proportional hazard model was used to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) to determine the association between the risk factors and CRC development. A robust sandwich covariance estimation model was used to evaluate family dependence. RESULTS: Among the total cohort, subjects of the Hakka ethnicity exhibited an increased CRC risk (HR = 1.62, 95% CI = 1.09-2.34); however, those who performed regular physical activity exhibited a decreased CRC risk (HR = 0.62, 95% CI = 0.41-0.88). The CRC risk was enhanced in MLH1 germline mutation carriers, with corresponding HRs of 1.72 (95% CI = 1.16-2.55) and 0.54 (95% CI = 0.34-0.83) among subjects of the Hakka ethnicity and those who performed regular physical activity, respectively. In addition, the total cohort with a manual occupation had a 1.56 times higher CRC risk (95% CI = 1.07-2.27) than did that with a skilled occupation. Moreover, MSH2 germline mutation carriers with blood group type B exhibited an increased risk of CRC development (HR = 2.64, 95% CI = 1.06-6.58) compared with those with blood group type O. CONCLUSION: The present study revealed that Hakka ethnicity, manual occupation, and blood group type B were associated with an increased CRC risk, whereas regular physical activity was associated with a decreased CRC risk in MLH1 and MSH2 germline mutation carriers.


Subject(s)
Adaptor Proteins, Signal Transducing/genetics , Colorectal Neoplasms, Hereditary Nonpolyposis/genetics , Colorectal Neoplasms/genetics , Genetic Predisposition to Disease , Germ-Line Mutation/genetics , MutS Homolog 2 Protein/genetics , Nuclear Proteins/genetics , Adult , DNA Mismatch Repair/genetics , Demography , Diet , Female , Humans , Life Style , Male , Middle Aged , Multivariate Analysis , MutL Protein Homolog 1 , Proportional Hazards Models , Risk Factors , Taiwan
11.
Med Sci Sports Exerc ; 45(5): 892-900, 2013 May.
Article in English | MEDLINE | ID: mdl-23190598

ABSTRACT

PURPOSE: Polymorphic variation in the angiotensin-converting enzyme (ACE) and α-actinin-3 (ACTN3) genes has been reported to be associated with endurance and/or power-related human performance. Our aim was to investigate whether polymorphisms in ACE and ACTN3 are associated with elite swimmer status in Caucasian and East Asian populations. METHODS: ACE I/D and ACTN3 R577X genotyping was carried out for 200 elite Caucasian swimmers from European, Commonwealth, Russian, and American cohorts (short and middle distance, ≤400 m, n = 130; long distance, >400 m, n = 70) and 326 elite Japanese and Taiwanese swimmers (short distance, ≤100 m, n = 166; middle distance, 200-400 m, n = 160). Genetic associations were evaluated by logistic regression and other tests accommodating multiple testing adjustment. RESULTS: ACE I/D was associated with swimmer status in Caucasians, with the D allele being overrepresented in short-and-middle-distance swimmers under both additive and I-allele-dominant models (permutation test P = 0.003 and P = 0.0005, respectively). ACE I/D was also associated with swimmer status in East Asians. In this group, however, the I allele was overrepresented in the short-distance swimmer group (permutation test P = 0.041 and P = 0.0098 under the additive and the D-allele-dominant models, respectively). ACTN3 R577X was not significantly associated with swimmer status in either Caucasians or East Asians. CONCLUSIONS: ACE I/D associations were observed in these elite swimmer cohorts, with different risk alleles responsible for the associations in swimmers of different ethnicities. The functional ACTN3 R577X polymorphism did not show any significant association with elite swimmer status, despite numerous previous reports of associations with "power/sprint" performance in other sports.


Subject(s)
Actinin/genetics , Asian People/genetics , Peptidyl-Dipeptidase A/genetics , Physical Endurance/genetics , Swimming/physiology , White People/genetics , Asia, Eastern , Female , Genome-Wide Association Study , Genotype , Genotyping Techniques/methods , Humans , INDEL Mutation , Male , Polymorphism, Genetic
12.
J Physiol Sci ; 62(2): 115-21, 2012 Mar.
Article in English | MEDLINE | ID: mdl-22247001

ABSTRACT

Physical performance of youth is influenced by various factors, including body composition, biological maturity status, level of habitual physical activity, and muscular strength. Muscular strength has been largely attributed to genetic effects. To exclude possible confounding effects from various acquired factors, this study examined the relationships between polymorphisms of the angiotensin-converting enzyme (ACE), α-actinin-3 (ACTN3), peroxisome proliferator-activated receptor delta (PPARD), and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PPARGC1A) genes and performance as measured by six fitness tests (handgrip strength of dominant hand, 30- and 60-s sit-ups, standing long jump, 60-m dash, and 800-m run) in 170 sedentary adolescent girls with the adjustment of anthropometric characteristics. We found that subjects with the ACE DD genotype were significantly heavier than those with I allele, while those with the ACTN3 RR genotype had higher fat-free mass percentage (FFM%) than those with the XX genotype. In addition, those with the PPARD TT genotype were significantly taller, heavier, and had a greater FFM than those with the CC genotype. Subjects with the ACE DD, ACTN3 RR and PPARD TC genotype had better performance in handgrip strength, 30- and 60-s sit-up tests, and standing long jump, respectively, when individual gene was analyzed independently after adjusting anthropometric characteristics. In the gene combination analysis, subjects with ACE DD, ACTN3 RR and PPARD TT genotype had significantly greater performance in handgrip strength. Overall, the results indicate that the genes studied have a modest influence on individual performance as assessed by specific fitness and strength tests in female late adolescents.


Subject(s)
Actinin/genetics , Heat-Shock Proteins/genetics , PPAR delta/genetics , Peptidyl-Dipeptidase A/genetics , Physical Fitness/physiology , Polymorphism, Genetic , Transcription Factors/genetics , Adolescent , Amino Acid Substitution , Base Sequence , DNA Primers/genetics , Female , Genetic Association Studies , Hand Strength/physiology , Humans , INDEL Mutation , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha , Polymorphism, Single Nucleotide , Taiwan
13.
High Alt Med Biol ; 6(3): 256-62, 2005.
Article in English | MEDLINE | ID: mdl-16185143

ABSTRACT

Altitude training is a frequently used method for enhancing endurance performance in athletes. But its acute effect on carbohydrate metabolism in cardiac muscle is unknown. In this study, we determined the acute effect of an exercise-hypoxia challenge on glycogen storage and GLUT4 protein expression in heart muscle. Sixteen male Sprague-Dawley rats were assigned to one of two groups: control (CTRL) and exercise-hypoxia (EX+HY). The exercise protocol consisted of swimming for 180 min twice, with a 45-min rest interval. Five hours after the exercise, the EX+HY rats were exposed to a 14% O(2) systemic hypoxia under normobaric condition for 12 h. After this hypoxia exposure, the EX+HY and control rats were given glucose orally (1 g/kg body weight) with stomach tube and recovered under normal condition for 16 h. Ventricular portion of the heart was used to determine the levels of glycogen, GLUT4 mRNA, and GLUT4 protein after recovery. We found that myocardial glycogen level was lowered by the exercise-hypoxia challenge (51% below control, p < 0.05), while GLUT4 mRNA was dramatically elevated (approximately 400% of the control level, p < 0.05). The acute exercise-hypoxia treatment did not affect GLUT1 protein level in the same tissue. The novel finding of the study was that the exercise-hypoxia treatment significantly induced GLUT4 gene expression in the cardiac muscle. This acute response appears to be associated with a sustained glycogen depletion of the muscle.


Subject(s)
Glucose Transporter Type 4/metabolism , Glycogen/metabolism , Hypoxia/physiopathology , Myocardium/metabolism , Physical Exertion , Altitude , Animals , Blood Glucose/metabolism , Blotting, Western , Glucose/administration & dosage , Glucose Transporter Type 1/metabolism , Glucose Transporter Type 4/genetics , Hypoxia/metabolism , Male , Physical Conditioning, Animal , RNA, Messenger/metabolism , Rats , Rats, Sprague-Dawley , Time Factors
14.
J Biomed Sci ; 11(6): 838-46, 2004.
Article in English | MEDLINE | ID: mdl-15591781

ABSTRACT

We compared the chronic effect of intermittent hypoxia and endurance training on the glucose tolerance and GLUT4 protein expression in rat skeletal muscle. Thirty-two Sprague-Dawley rats were matched for weight and assigned to one of the following four groups: control, endurance training, hypoxia, or hypoxia followed by endurance training. Hypoxic treatment consisted of breathing 14% O2 for 12 h/day under normobaric conditions, and the training protocol consisted of making animals swim 2 times for 3 h/day. At the end of the 3rd week, an oral glucose tolerance test (OGTT) was performed 16 h after treatments. At the end of the 4th week, GLUT4 protein, mRNA, and glycogen storage in skeletal muscle were determined. Endurance training significantly improved OGTT results. Glycogen content and GLUT4 protein expression in the plantaris and red gastrocnemius, but not in the soleus or white gastrocnemius muscles, were also elevated. Chronic intermittent hypoxia also improved OGTT results, but did not alter GLUT4 protein expression. Additionally, hypoxia followed by exercise training produced significant increases in GLUT4 protein and mRNA in a greater number of muscles compared to endurance training alone. Both exercise training and hypoxia significantly reduced body mass, and an additive effect of both treatments was found. In conclusion, chronic intermittent hypoxia improved glucose tolerance in the absence of increased GLUT4 protein expression. This treatment facilitated the exercise training effect on muscle GLUT4 expression and glycogen storage. These new findings open the possibility of utilizing intermittent hypoxia, with or without exercise training, for the prevention and clinical treatment of type 2 diabetes or insulin resistance.


Subject(s)
Hypoxia , Monosaccharide Transport Proteins/biosynthesis , Muscle Proteins/biosynthesis , Muscle, Skeletal/metabolism , Muscles/metabolism , Physical Conditioning, Animal , Analysis of Variance , Animals , Blotting, Northern , Blotting, Western , Body Weight , Glucose Tolerance Test , Glucose Transporter Type 4 , Glycogen/metabolism , Insulin/metabolism , Insulin Resistance , Male , RNA, Messenger/metabolism , Rats , Rats, Sprague-Dawley , Time Factors
15.
Jpn J Physiol ; 54(4): 357-63, 2004 Aug.
Article in English | MEDLINE | ID: mdl-15631691

ABSTRACT

Altitude training is a common method used to enhance endurance performance in athletes. We have examined the interactive effect of exercise training and chronic hypoxic on glycogen storage and GLUT4 protein expression in cardiac muscles. Thirty-two male Sprague-Dawley rats were weight balanced and assigned to one of the following four groups: control, exercise, hypoxia, and hypoxia-exercise. Rats with hypoxic treatment (breathing 14% O(2) for 12 hr/d) were exposed under normobaric conditions. The training protocol consisted of swimming for two 3-hr periods per day for 4 weeks. Glycogen content, GLUT4 protein, and mRNA of all rats were determined 16 hr after treatments. Four-week exercise training without hypoxia significantly elevated myocardial glycogen level by 45%. The chronic hypoxic-exercise training elevated the myocardial glycogen level by 67% above control level, significantly greater than the exercise group. Chronic hypoxia, exercise training, and hypoxia-exercise training significantly elevated GLUT4 protein by 40-70% in cardiac muscles. Chronic hypoxia significantly elevates the GLUT1 protein level independent of exercise training. The new finding in this study was that GLUT4 gene expression in cardiac muscle can be stimulated by exercise training with hypoxia treatments. This molecular adaptation appears to be associated with the observed increase in glycogen storage of the muscle.


Subject(s)
Altitude , Heart/physiology , Hypoxia/physiopathology , Monosaccharide Transport Proteins/biosynthesis , Muscle Proteins/biosynthesis , Physical Conditioning, Animal/physiology , Animals , Glucose Transporter Type 4 , Glycogen/metabolism , Male , Rats , Rats, Sprague-Dawley
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