Dataset Information

Effects of bedrest and hypoxia on human skeletal muscle miRNA expression

ABSTRACT: The present study concerns the effects of 21 days of sustained recumbence (bedrest) and hypoxia, alone and in combination, on skeletal muscle microRNA expression. 14 male subjects participated in 3 experimental campaigns in a counterbalanced fashion: normoxic bedrest (NBR), hypoxic bedrest (HBR) and hypoxic ambulatory confinement (HAMB), both hypoxic conditions with FO2 = 0.141 and PIO2 = 90 ± 0.4 mmHg, equivalent to an altitude of ≈ 4000 m). Each intervention (bedrest or ambulatory confinement) lasted 21 days, and the interventions were separated by a 4-month wash-out/recovery period. The order in which each subject undertook the interventions is denoted 'Intervention_order' Throughout both bedrest interventions, each subject remained in a horizontal position at all times. He was allowed one pillow for the head and to occasionally lean on an elbow while eating or being transferred to a gurney. Muscular exercise was prohibited. During the HAMB confinement, each subject was allowed to move freely within the hypoxic area. To mimic a normal level of physical activity subjects performed 30 minutes of low-to-moderate-intensity exercise twice daily. Muscle samples from Vastus lateralis.

ORGANISM(S): synthetic construct Homo sapiens

PROVIDER: GSE74469 | GEO | 2016/05/04

SECONDARY ACCESSION(S): PRJNA300517

REPOSITORIES: GEO

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Project description:The study has been described in the following paper: Gianni Parise, Stuart M. Phillips, Jan J. Kaczor and Mark A. Tarnopolsky (2005). Antioxidant enzyme activity is up-regulated after unilateral resistance exercise training in older adults. Free Radical Biology and Medicine, Volume 39, Issue 2, 15 July 2005, Pages 289-295 We cite the following three paragraphs from this paper: "MATERIALS AND METHODS Subjects Twelve men (71.2 ± 6.5 y) volunteered to participate in a 12 week uni-lateral leg resistance training program (Table 1). All subjects underwent a thorough screening process before being admitted into the study. Subjects were first screened by telephone, and were then subject to a medical evaluation. Consent from their family physician was required, and then all potential subjects underwent a resting electrocardiogram, and a sub-maximal graded exercise test on a bicycle ergometer witih a 12-lead ECG. Exclusion criteria included: evidence of coronary hear disease; congestive heart failure; uncontrolled hypertension; chronic obstructive pulmonary disease; diabetes mellitus; renal failure; major orthopaedic disability; and smoking. None of the subjects had ever participated in a structured exercise program. After subjects were advised of the benefits and risks of participation, subjects gave their written informed consent. The study was approved by the McMaster University and Hamilton Health Sciences Research Ethics Board and conferred to the principles of the declaration of Helsinki. Exercise Training Resistance training was performed three times weekly on non-consecutive days (Monday, Wednesday, and Friday) for 12 weeks, under strict supervision. Prior to and after each training session subjects were required to perform passive stretching. Resistance exercise for each session consisted of 3 sets of 10 repetitions for each of leg press and leg extension. Training progressed from one set of each exercise at 50% of the initial 1 repetition maximum (1RM) to 3 sets at 80% of 1RM over the training period. Training logs were kept to record the volume and intensity of each session. The 1RM was re-evaluated every 2 weeks, and the training load was adjusted accordingly. All exercises were performed on universal strength training equipment (Universal Gym Equipment, Inc., Cedar Rapids, Iowa). Muscle Biopsy A muscle biopsy was taken from the vastus lateralis muscle of both legs before as well as after the training period, 20 cm proximal to the knee joint using a modified Bergström needle (5 mm diameter) with suction modification. The biopsy specimen was dissected of fat and connective tissue and immediately frozen in liquid nitrogen. All samples were stored at -80 °C for subsequent analysis. All subjects were required to abstain from strenuous physical activity for 48 hours prior to the testing session. The non-trained leg performed an acute bout of exercise at the same relative intensity of the training leg to allow for the determination of the effect of training and the effect of acute resistance exercise." Additional Notes: 1) The samples of 8 out 12 were used in the gene expression study. 2) The 2 factors in this study are: 2.1) Leg - Left or Right 2.2) Training - Baseline: samples taken on each leg before exercise - Resistance Training: one of the legs was subject to resistance training followed by acute exercise - Acute Exercise: the other leg had only the acute exercise 3) The baseline samples will be used for right versus left leg comparison to see variance between legs for human experimentation technical issues. The samples from Resistance or Acute Exercise will be compared to corresponding baseline samples to evaluate the effect of both exercise programs on gene expression.

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Effects of bedrest and hypoxia on human skeletal muscle miRNA expression

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