A longitudinal study of muscle rehabilitation in the lower leg after cast removal using Magnetic Resonance Imaging and strength assessment

Acknowledgements We thank the A&E nurses and plaster technicians for identifying suitable patients, the MRI radiographers for performing the scanning, Dr Scott Semple for invaluable help in some of the pilot studies and Mr E. C. Stevenson for constructing the footrest used in the scanner. We are very grateful to the dedicated patients themselves who gave considerable amounts of time to come in for scanning, exercise and assessment during the course of this study.Peer reviewedPublisher PD

A longitudinal study of muscle rehabilitation in the lower leg after cast removal using magnetic resonance imaging and strength assessment

Magnetic resonance imaging (MRI) was used to investigate muscle rehabilitation following cast immobilization. The aim was to explore MRI as an imaging biomarker of muscle function. Sixteen patients completed an eight-week rehabilitation programme following six weeks of cast immobilization for an ankle fracture. MRI of the lower leg was performed at two-week intervals for 14 weeks. Total volume and anatomical cross-sectional areas at 70% of the distance from lateral malleolus to tibial tuberosity (ACSA) were measured for tibialis anterior (TA), medial and lateral gastrocnemius (GM and GL) and soleus (SOL). Pennation angle of muscle fascicules was measured at the same position in GM. Fractional fat/water contents and T2 relaxation times before and after exercise were calculated. Strength was measured as maximum isometric torque developed in plantar- and dorsi-flexion. Torque increased by (mean [SD]) 1.10 (0.32) N m day−1 in males, 0.74 (0.43) N m day−1 in females in plantar-flexion (0.9% of final strength per day), and 0.36 (0.15) N m day−1 in males, 0.28 (0.19) N m day−1 in females in dorsi-flexion (1.1% per day). Neither difference between males and females was significant. Volume and ACSA of muscles recovered by week 14 apart from SOL which was still 6.8% smaller (p = 0.006) than the contralateral leg. T2 peaked at the end of the cast period for TA and SOL, and at week 8 for GM before returning to baseline. Pennation angle recovered rapidly following cast removal. Quantitative MRI can generate markers of muscle biomechanics and indicates that many of these return to baseline within eight weeks of remobilization

Circulating Proteomic Signatures of Chronological Age

To elucidate the proteomic features of aging in plasma, the subproteome targeted by the SOMAscan assay was profiled in blood samples from 202 females from the TwinsUK cohort. Findings were replicated in 677 independent individuals from the AddNeuroMed, Alzheimer's Research UK, and Dementia Case Registry cohorts. Results were further validated using RNAseq data from whole blood in TwinsUK and the most significant proteins were tested for association with aging-related phenotypes after adjustment for age. Eleven proteins were associated with chronological age and were replicated at protein level in an independent population. These were further investigated at gene expression level in 384 females from the TwinsUK cohort. The two most strongly associated proteins were chordin-like protein 1 (meta-analysis β [SE] = 0.013 [0.001], p = 3.66 × 10−46) and pleiotrophin (0.012 [0.005], p = 3.88 × 10−41). Chordin-like protein 1 was also significantly correlated with birthweight (0.06 [0.02], p = 0.005) and with the individual Framingham 10-years cardiovascular risk scores in TwinsUK (0.71 [0.18], p = 9.9 × 10−5). Pleiotrophin is a secreted growth factor with a plethora of functions in multiple tissues and known to be a marker for cardiovascular risk and osteoporosis. Our study highlights the importance of proteomics to identify some molecular mechanisms involved in human health and agin

Age-related changes in the effects of strength training on lower leg muscles in healthy individuals measured using MRI

BACKGROUND: We previously measured the rate of regaining muscle strength during rehabilitation of lower leg muscles in patients following lower leg casting. Our primary aim in this study was to measure the rate of gain of strength in healthy individuals undergoing a similar training regime. Our secondary aim was to test the ability of MRI to provide a biomarker for muscle function. METHODS: Men and women were recruited in three age groups: 20-30, 50-65 and over 70 years. Their response to resistance training of the right lower leg twice a week for 8 weeks was monitored using a dynamometer and MRI of tibialis anterior, soleus and gastrocnemius muscles at 2 weekly intervals to measure muscle size (anatomical cross-sectional area (ACSA)) and quality (T2 relaxation). Forty-four volunteers completed the study. RESULTS: Baseline strength declined with age. Training had no effect in middle-aged females or in elderly men in dorsiflexion. Other groups significantly increased both plantarflexion and dorsiflexion strength at rates up to 5.5 N m week(-1) in young females in plantarflexion and 1.25 N m week(-1) in young males in dorsiflexion. No changes were observed in ACSA or T2 in any age group in any muscle. CONCLUSION: Exercise training improves muscle strength in males at all ages except the elderly in dorsiflexion. Responses in females were less clear with variation across age and muscle groups. These results were not reflected in simple MRI measures that do not, therefore, provide a good biomarker for muscle atrophy or the efficacy of rehabilitation

Metabolomic study of carotid-femoral pulse-wave velocity in women

Objective: Carotid-femoral pulse-wave velocity (PWV) is a measure of aortic stiffness that is strongly associated with increased risk of cardiovascular morbidity and mortality. The aim of the current study was to identify the molecular markers and the pathways involved in differences in PWV in women, in order to further understand the regulation of arterial stiffening. Methods: A total of 280 known metabolites were measured in 1797 female twins (age range: 18-84 years) not on any antihypertensive medication. Metabolites associated with PWV (after adjustment for age, BMI, metabolite batch, and family relatedness) were entered into a backward linear regression. Transcriptomic analyses were further performed on the top compounds identified. Results: Twelve metabolites were associated with PWV (P<1.8-10-4). One of the most strongly associated metabolites was uridine, which was not associated with blood pressure (BP) and traditional risk factors but correlated significantly with the gene-expression levels of the purinergic receptor P2RY2 (Beta=0.010, SE=0.003, P=0.007), suggesting that it may play a role in regulating endothelial nitric oxide synthase phosphorylation. On the other hand, phenylacetylglutamine was strongly associated with both PWV and BP. Conclusion: Circulating levels of uridine, phenylacetylglutamine, and serine appear strongly correlated with PWV in women

Integrating HDAd5/35++ vectors as a new platform for HSC gene therapy of hemoglobinopathies

We generated an integrating, CD46-targeted, helper-dependent adenovirus HDAd5/35++ vector system for hematopoietic stem cell (HSC) gene therapy. The ∼12-kb transgene cassette included a β-globin locus control region (LCR)/promoter driven human γ-globin gene and an elongation factor alpha-1 (EF1α)-mgmtP140K expression cassette, which allows for drug-controlled increase of γ-globin-expressing erythrocytes. We transduced bone marrow lineage-depleted cells from human CD46-transgenic mice and transplanted them into lethally irradiated recipients. The percentage of γ-globin-positive cells in peripheral blood erythrocytes in primary and secondary transplant recipients was stable and greater than 90%. The γ-globin level was 10%–20% of adult mouse globin. Transgene integration, mediated by a hyperactive Sleeping Beauty SB100x transposase, was random, without a preference for genes. A second set of studies was performed with peripheral blood CD34+ cells from mobilized donors. 10 weeks after transplantation of transduced cells, human cells were harvested from the bone marrow and differentiated ex vivo into erythroid cells. Erythroid cells expressed γ-globin at a level of 20% of adult α-globin. Our studies suggest that HDAd35++ vectors allow for efficient transduction of long-term repopulating HSCs and high-level, almost pancellular γ-globin expression in erythrocytes. Furthermore, our HDAd5/35++ vectors have a larger insert capacity and a safer integration pattern than currently used lentivirus vectors

Metabolomic study of carotid–femoral pulse-wave velocity in women

Objective: Carotid–femoral pulse-wave velocity (PWV) is a measure of aortic stiffness that is strongly associated with increased risk of cardiovascular morbidity and mortality. The aim of the current study was to identify the molecular markers and the pathways involved in differences in PWV in women, in order to further understand the regulation of arterial stiffening.<p></p> Methods: A total of 280 known metabolites were measured in 1797 female twins (age range: 18–84 years) not on any antihypertensive medication. Metabolites associated with PWV (after adjustment for age, BMI, metabolite batch, and family relatedness) were entered into a backward linear regression. Transcriptomic analyses were further performed on the top compounds identified.<p></p> Results: Twelve metabolites were associated with PWV (P < 1.8 × 10-4). One of the most strongly associated metabolites was uridine, which was not associated with blood pressure (BP) and traditional risk factors but correlated significantly with the gene-expression levels of the purinergic receptor P2RY2 (Beta = -0.010, SE = 0.003, P = 0.007), suggesting that it may play a role in regulating endothelial nitric oxide synthase phosphorylation. On the other hand, phenylacetylglutamine was strongly associated with both PWV and BP.<p></p> Conclusion: Circulating levels of uridine, phenylacetylglutamine, and serine appear strongly correlated with PWV in women.<p></p&gt

Biomarkers for Type 2 Diabetes and Impaired Fasting Glucose Using a Nontargeted Metabolomics Approach

Using a nontargeted metabolomics approach of 447 fasting plasma metabolites, we searched for novel molecular markers that arise before and after hyperglycemia in a large populationbased cohort of 2,204 females (115 type 2 diabetic [T2D] case subjects, 192 individuals with impaired fasting glucose [IFG], and 1,897 control subjects) from TwinsUK. Forty-two metabolites from three major fuel sources (carbohydrates, lipids, and proteins) were found to significantly correlate with T2D after adjusting for multiple testing; of these, 22 were previously reported as associated with T2D or insulin resistance. Fourteen metabolites were found to be associated with IFG. Among the metabolites identified, the branched-chain keto-acid metabolite 3-methyl-2-oxovalerate was the strongest predictive biomarker for IFG after glucose (odds ratio [OR] 1.65 [95% CI 1.39-1.95], P = 8.46 3 1029) and was moderately heritable (h2 = 0.20). The association was replicated in an independent population (n = 720, OR 1.68 [ 1.34-2.11], P = 6.52 3 1026) and validated in 189 twins with urine metabolomics taken at the same time as plasma (OR 1.87 [1.27-2.75], P = 1 3 1023). Results confirm an important role for catabolism of branched-chain amino acids in T2D and IFG. In conclusion, this T2D-IFG biomarker study has surveyed the broadest panel of nontargeted metabolites to date, revealing both novel and known associated metabolites and providing potential novel targets for clinical prediction and a deeper understanding of causal mechanisms

Metabolomic markers reveal novel pathways of ageing and early development in human populations

Background Human ageing is a complex, multifactorial process and early developmental factors affect health outcomes in old age. Methods Metabolomic profiling on fasting blood was carried out in 6055 individuals from the UK. Stepwise regression was performed to identify a panel of independent metabolites which could be used as a surrogate for age. We also investigated the association with birthweight overall and within identical discordant twins and with genome-wide methylation levels. Results We identified a panel of 22 metabolites which combined are strongly correlated with age (R2=59%) and with age-related clinical traits independently of age. One particular metabolite, C-glycosyl tryptophan (C-glyTrp), correlated strongly with age (beta=0.03, SE=0.001, P=7.0×10-157) and lung function (FEV1 beta=-0.04, SE=0.008, P=1.8×10-8 adjusted for age and confounders) and was replicated in an independent population (n=887). C-glyTrp was also associated with bone mineral density (beta=-0.01, SE=0.002, P=1.9×10-6) and birthweight (beta=-0.06, SE=0.01, P=2.5×10-9). The difference in C-glyTrp levels explained 9.4% of the variance in the difference in birthweight between monozygotic twins. An epigenome-wide association study in 172 individuals identified three CpG-sites, associated with levels of C-glyTrp (P < 2×10-6). We replicated one CpG site in the promoter of the WDR85 gene in an independent sample of 350 individuals (beta=-0.20, SE=0.04, P=2.9×10-8). WDR85 is a regulator of translation elongation factor 2, essential for protein synthesis in eukaryotes. Conclusions Our data illustrate how metabolomic profiling linked with epigenetic studies can identify some key molecular mechanisms potentially determined in early development that produce long-term physiological changes influencing human health and ageing

Circulating Proteomic Signatures of Chronological Age

To elucidate the proteomic features of aging in plasma, the subproteome targeted by the SOMAscan assay was profiled in blood samples from 202 females from the TwinsUK cohort. Findings were replicated in 677 independent individuals from the AddNeuroMed, Alzheimer's Research UK, and Dementia Case Registry cohorts. Results were further validated using RNAseq data from whole blood in TwinsUK and the most significant proteins were tested for association with aging-related phenotypes after adjustment for age. Eleven proteins were associated with chronological age and were replicated at protein level in an independent population. These were further investigated at gene expression level in 384 females from the TwinsUK cohort. The two most strongly associated proteins were chordin-like protein 1 (meta-analysis β [SE] = 0.013 [0.001], p = 3.66 × 10(-46)) and pleiotrophin (0.012 [0.005], p = 3.88 × 10(-41)). Chordin-like protein 1 was also significantly correlated with birthweight (0.06 [0.02], p = 0.005) and with the individual Framingham 10-years cardiovascular risk scores in TwinsUK (0.71 [0.18], p = 9.9 × 10(-5)). Pleiotrophin is a secreted growth factor with a plethora of functions in multiple tissues and known to be a marker for cardiovascular risk and osteoporosis. Our study highlights the importance of proteomics to identify some molecular mechanisms involved in human health and aging