Hypertrophic Effects Research Articles

Muscle Hypertrophy and Architectural Changes in Response to Eight-Week Neuromuscular Electrical Stimulation Training in Healthy Older People

Loss of muscle mass of the lower limbs and of the spine extensors markedly impairs locomotor ability and spine stability in old age. In this study, we investigated whether 8 w of neuromuscular electrical stimulation (NMES) improves size and architecture of the lumbar multifidus (LM) and vastus lateralis (VL) along with locomotor ability in healthy older individuals. Eight volunteers (aged 65 ≥ years) performed NMES 3 times/week. Eight sex- and age-matched individuals served as controls. Functional tests (Timed Up and Go test (TUG) and Five Times Sit-to-Stand Test (FTSST)), VL muscle architecture (muscle thickness (MT), pennation angle (PA), and fiber length (FL)), along with VL cross-sectional area (CSA) and both sides of LM were measured before and after by ultrasound. By the end of the training period, MT and CSA of VL increased by 8.6% and 11.4%, respectively. No significant increases were observed in FL and PA. LM CSA increased by 5.6% (left) and 7.1% (right). Interestingly, all VL architectural parameters significantly decreased in the control group. The combined NMES had a large significant effect on TUG (r = 0.50, p = 0.046). These results extend previous findings on the hypertrophic effects of NMES training, suggesting to be a useful mean for combating age-related sarcopenia.

Abstract P230: Depletion Of Cyclic-gmp Levels And The Inhibition Of Cgks Activate P21 Cip1 /p27 Kip1 Pathways And Trigger High Blood Pressure With Renal Fibrosis And Dysfunction

Targeted-deletion of Npr1 gene (coding for guanylyl cyclase/natriuretic peptide receptor-A, GC-A/NPRA) exhibits hypertrophic and proliferative effects in target organs of Npr 1 gene-knockout mice. Fibrosis and hypertrophy are regulated by p21 Cip1 and p27 Kip1 , cell-cycle regulatory proteins that inhibit target cyclin and cyclin-dependent kinase (cyclin-CDK) complex. We examined the activation of CDK blocker (p21 Cip1 /p27 Kip1 ) in Npr1 gene-knockout (0-copy; Npr 1 -/- ) mice and guanylyl cyclase (GC) inhibitor, A71915-treated and cGMP-dependent protein kinase (cGK) inhibitor, Rp-8-Br-cGMPS (Rp)-treated wild-type 2-copy ( Npr 1 +/+ ) and gene-duplicated 4-copy ( Npr 1 ++/++ ) mice. Blood pressure (BP) was significantly higher in 0-copy mice (138.6 ± 3.1 mmHg) and lower in 4-copy mice (86.0 ± 2.8 mmHg) than 2-copy mice (102.2 ± 1.7 mmHg). Treatment with A71915 and Rp showed significant changes in BP in 2-copy mice but caused only small increase in 4-copy mice. We found a significant decrease in renal cGMP levels with diminished cGK activity in 0-copy mice (p<0.0001) as well as A71915-treated (p<0.001) and Rp-treated (p<0.05) 2-copy and 4-copy mice as compared with controls animals. While significant activation of p-Erk1/2 (3-fold), p-p38MAPK (4-fold), p21 Cip1 (6-fold), and p27 Kip1 (5-fold) occurred in 0-copy, A71915-treated 2-copy, and A71915-treated 4-copy mice but Rp treatment caused minimal changes compared to control mice. There were significant increases in the proinflammatory cytokines, including TNF-α (6-fold), and IL-6 (3-fold) and profibrotic cytokine TGF-β1 (4-fold) in plasma and kidneys of 0-copy and A791915-treated 2-copy mice, but less in A71915-treated 4-copy mice than controls. Progressive renal pathology, including fibrosis, mesangial matrix expansion, tubular hypertrophy, and perivascular infiltration were significantly scored in 0-copy and A71915-treated 2-copy mice, but did so minimally in 4-copy mice compared with controls. The present results suggest that Npr1 has a pivotal role in inhibiting the renal fibrosis and pathology and exerts renal protective effects through the cGMP/cGK axis by repressing the CDK inhibitors, p21 Cip1 and p27 Kip1 . This work was supported by NIH grant (HL062147).

Parvalbumin Affects Skeletal Muscle Trophism Through Modulation of Mitochondrial Calcium Uptake

Parvalbumin (PV) is a cytosolic EF-hand calcium-binding protein highly expressed in fast skeletal muscle fibers. By acting as a Ca2+ buffer, PV contributes to increase the relaxation rate in skeletal muscle fibers. More recently, PV has been described as one of the “atrogenes”, the collection of genes commonly up- and downregulated during both disuse and systemic types of muscle atrophy. Here we exploited the murine strain lacking PV (PV-/-) to explore the link between PV function as Ca2+ buffer and the control of muscle trophism. First, by using denervation as an acute model of atrophy, we found a lower muscle mass loss in PV-/- than in WT mice. Then, by acutely silencing and overexpressing PV in adult muscles of WT mice, we discovered that its downregulation was accompanied by hypertrophy and its upregulation by atrophy. Using compartment specific Ca2+ probes, we also explored three cellular compartments: cytosol, sarcoplasmic reticulum and mitochondria. The lack of PV was associated with an increased Ca2+ uptake in mitochondria, which could be supported by MCU complex components overexpression and an increased mitochondria volume. Intriguingly, MCU silencing abolished the hypertrophic effect of PV ablation on fiber size, suggesting a mitochondrial Ca2+-dependent mechanism of control of muscle trophism. This is corroborated by the induction of the expression of the mitochondrial Ca2+-dependent PGC1-a4 that promotes skeletal muscle hypertrophy. These data reveal a novel role of PV that links the control of cytosolic Ca2+ concentration to mitochondrial adaptations, ultimately leading to the control of muscle mass.

Improvements in skeletal muscle fiber size with resistance training are age-dependent in older adults: a systematic review and meta-analysis.

As studies examining the hypertrophic effects of resistance training (RT) at the cellular level have produced inconsistent results, we performed a systematic review and meta-analysis to investigate muscle fiber size before and after a structured RT intervention in older adults. A random-effects model was used to calculate mean effect size (ES) and 95% confidence intervals (CI). Thirty-five studies were included (age range: 59.0-88.5 yr), and 44 and 30 effects were used to estimate RT impact on myosin heavy chain (MHC) I and II fiber size. RT produced moderate-to-large increases in MHC I (ES = +0.51, 95%CI +0.31 to +0.71; P < 0.001) and II (ES = +0.81, 95%CI +0.56 to +1.05; P < 0.001) fiber size, with men and women having a similar response. Age was negatively associated with change in muscle fiber size for both fiber types (MHC I: R2 = 0.11, β = -0.33, P = 0.002; MHC II: R2 = 0.10, β = -0.32, P = 0.04), indicating a less robust hypertrophic response as age increases in older adults. Unexpectedly, a higher training intensity (defined as percentage of one-repetition maximum) was associated with a smaller increase in MHC II fiber size (R2 = 15.09%, β = -0.39, P = 0.01). Notably, MHC II fiber subtypes (IIA, IIX, IIAX) were examined less frequently, but RT improved their size. Overall, our findings indicate that RT induces cellular hypertrophy in older adults, although the effect is attenuated with increasing age. In addition, hypertrophy of MHC II fibers was reduced with higher training intensity, which may suggest a failure of muscle fibers to hypertrophy in response to high loads in older adults.

Muscle Atrophy: Counteracting Muscle Atrophy on Earth and in Space via Nanofluidics Delivery of Formoterol (Adv. Therap. 7/2020)

In article number 2000014 Alessandro Grattoni and co-workers present the first-ever in vivo study of an implantable drug delivery device in microgravity aboard the International Space Station. In this unprecedented research endeavor, the muscle hypertrophic effect of nanofluidic-mediated sustained low dose elution of formoterol is demonstrated in rodents in space as well as on Earth.

Exercise Suppresses The Ubiquitin-proteasome System In The Skeletal Muscle Of Obese Women Following Bariatric Surgery

Muscle wasting observed in obese women undergoing bariatric surgery is likely related to altered abnormal intramyocellular signaling. Exercise may reestablish the anabolic capacity in this condition. PURPOSE: We examined the effects of exercise training on the main pathways related to skeletal muscle plasticity in obese women undergoing bariatric surgery. METHODS: Women with severe obesity were randomly allocated to either bariatric surgery (RYGB) or bariatric surgery followed by exercise (RYGB+ET). A 6-month, three-times-a-week, supervised, combined aerobic and resistance training program started 3 months after surgery for RYGB+ET, while RYGB followed standard of care. We assessed the transcriptome (RNA-seq) from skeletal muscle samples obtained by muscle biopsies (n = 6 per group) at baseline (PRE) and 9 months after surgery (POST9). We tested whether a set of genes defined a priori were differentially expressed utilizing the Gene Set Enrichment Analysis. Significance was assumed at a fold change > 1.5, P-value < 0.05, and FDR (false discovery rate) < 0.1. To validate the RNA-seq findings, we performed real time-polymerase chain reaction assays (n = 15 per group) for targeted genes. RESULTS: Pathway-level analysis showed that exercise significantly suppressed ubiquitin mediated proteolysis pathway (normalized enrichment scores [NES]: 1.7, P=0.01, FDR=0.09). Atrogin-1 gene expression was suppressed in the exercised group at POST9 in comparison to PRE, and POST3, and also when compared with the non-exercised group at POST9 (estimated mean difference [RYGB vs. RYGB+ET at POST9]: -1.97, CI95%=-3.0 to -0.8, P=0.01). MuRF-1 gene expression decreased after surgery and kept reduced after the intervention for both groups (main time effect: P<0.01 for both). CONCLUSIONS: Our data suggest that a 6-month, exercise training program suppresses the ubiquitin-proteasome system via the downregulation of Atrogin-1 in obese woman undergoing bariatric surgery. This may elucidate a molecular mechanism that partially explains muscle wasting following bariatric surgery and the exercise-induced hypertrophic effect in this condition.Clinicaltrials.gov: NCT02441361

Resveratrol counteracts IL-1β-mediated impairment of extracellular matrix deposition in 3D articular chondrocyte constructs.

When aiming at cell-based therapies in osteoarthritis (OA), proinflammatory conditions mediated by cytokines such as IL-1β need to be considered. In recent studies, the phytoalexin resveratrol (RSV) has exhibited potent anti-inflammatory properties. However, long-term effects on 3D cartilaginous constructs under inflammatory conditions with regard to tissue quality, especially extracellular matrix (ECM) composition, have remained unexplored. Therefore, we employed long-term model cultures for cell-based therapies in an in vitro OA environment and evaluated effects of RSV. Pellet constructs made from expanded porcine articular chondrocytes were cultured with either IL-1β (1-10 ng/ml) or RSV (50 μM) alone, or a cotreatment with both agents. Treatments were applied for 14 days, either directly after pellet formation or after a preculture period of 7 days. Culture with IL-1β (10 ng/ml) decreased pellet size and DNA amount and severely compromised glycosaminoglycan (GAG) and collagen content. Cotreatment with RSV distinctly counteracted the proinflammatory catabolism and led to partial rescue of the ECM composition in both culture systems, with especially strong effects on GAG. Marked MMP13 expression was detected in IL-1β-treated pellets, but none upon RSV cotreatment. Expression of collagen type I was increased upon IL-1β treatment and still observed when adding RSV, whereas collagen type X, indicating hypertrophy, was detected exclusively in pellets treated with RSV alone. In conclusion, RSV can counteract IL-1β-mediated degradation and distinctly improve cartilaginous ECM deposition in 3D long-term inflammatory cultures. Nevertheless, potential hypertrophic effects should be taken into account when considering RSV as cotreatment for articular cartilage repair techniques.

Role of sodium tetraborate as a cardioprotective or competitive agent: Modulation of hypertrophic intracellular signals

Boron is an essential trace element in cellular metabolism; however, the molecular mechanism of boron in the heart is unclear. In this study, we examined the effect of sodium tetraborate (as boron source) as a possible protective agent or competitive inhibitor of cardiac hypertrophy in an in vitro murine model.We evaluated different previously reported sodium tetraborate concentrations and it was found that 13 μM improves viability without affecting the cellular structure.We demonstrated that cardiomyocytes pretreated with sodium tetraborate prevents cellular damage induced by isoproterenol (cardioprotective effect) by increasing proliferation rate and inhibiting apoptosis. In addition, the reduction of the expression of the α1AR and β1AR adrenergic receptors as well as Erk1/2 was notable. Consequently, the expression of the early response genes c-myc, c-fos and c-jun was delayed. Also, the expression of GATA-4, NFAT, NKx2.5 and myogenin transcription factors involved in sarcomere synthesis declined. In contrast, cardiomyocytes, when treated simultaneously with sodium tetraborate and isoproterenol, did not increase their size (cytoplasmic gain), but an increase in apoptosis levels was observed; therefore, the proliferation rate was reduced. Although the mRNA levels of α1AR and β1AR as well as Erk1/2 and Akt1 were low at 24 h, their expression increased to 48 h. Notably, the mRNA of expression levels of c-myc, c-fos and c-jun were lower than those determined in the control, while the transcription factors GATA-4, MEF2c, Nkx2.5, NFAT and CDk9 were determined in most cells.These results suggest that pretreatment with sodium tetraborate in cardiomyocytes inhibits the hypertrophic effect. However, sodium tetraborate attenuates isoproterenol induced hypertrophy damage in cardiomyocytes when these two compounds are added simultaneously.

The determination of the cross-sectional area of the lumbar erector spinae muscles of Olympic style weightlifting athletes by using MRI.

The study aims to measure the cross-sectional area of the lumbar erector spinae muscles from L3-L4 intervertebral disc levels by using magnetic resonance images of Olympic style weightlifting athletes (male n= 15, female n= 15) and sedentary individuals (male n= 15, female n= 15). A 1.5 Tesla device was used for the magnetic resonance imaging process of all participants. The images were then executed in ImageJ software and the cross-sectional area was measured after the required synchronization steps were conducted. On the images taken from L3-L4 intervertebral disc levels, we observed that right-left cross-sectional area measurements of erector spinae muscles of sedentary males and females in the control groups were smaller than those of male and female athletes in Olympic style weightlifting. We also found a symmetry between right-left cross-sectional area measurements of groups of athletes. From the study findings, we might conclude that trainings of Olympic style weightlifting possess a hypertrophic effect on the cross-sectional area of erector spinae muscles of Olympic style weightlifting athletes.

Imine stilbene analog ameliorate isoproterenol-induced cardiac hypertrophy and hydrogen peroxide-induced apoptosis

Cardiac hypertrophy is an adaptive response to stress, in order to maintain proper cardiac function. However, sustained stress leads to pathological hypertrophy accompanied by maladaptive responses and ultimately heart failure. At the cellular level, cardiomyocyte hypertrophy is characterized by an increase in myocyte size, reactivation of the fetal gene markers, disassembly of the sarcomere and transcriptional remodelling which are regulated by heart-specific transcription factors like MEF2, GATA4 and immediate early genes like c-jun and c-fos.2. It has been explored and established that the hypertrophic process is associated by oxidative stress and mediated by pathways involving several terminal stress kinases like P38, JNK and ERK1/2. Stilbenoids are bioactive polyphenols and earlier studies have shown that imine stilbene exert cardioprotective and anti aging effects by acting as modulators of Sirt1. The present study was aimed at designing and synthesizing a series of imine stilbene analogs and investigate its anti hypertrophic effects and regulatory mechanism in cardiac hypertrophy and apoptosis. Interestingly one of the analog, compound 3e (10 μM) alleviated isoproterenol (ISO, 25 μM) induced hypertrophy in rat cardiomyocyte (H9c2) cells by showing a marked decrease in the myocyte size. Further, compound 3e also restored the cardiac function by activating the metabolic stress sensor, AMPK. Moreover, molecular docking studies showed stable binding between compound 3e and GSK3β suggesting that compound 3e may directly regulate GSK3β activity and ameliorate ISO-induced cardiac hypertrophy. In agreement with this, compound 3e also modulated the crosstalk of all the hypertrophy inducing terminal Kinases by bringing down the expression to near control conditions. The compound also relieved H2O2 (100 μM) mediated ROS and normalized abnormal mitochondrial oxygen demand in hypertrophic conditions indicating the possibility of the compound to show promise in playing a role in cardiac hypertrophy.

Cardiomyocyte Specific Knock‐out of Erythropoietin Has Adaptive Non‐Erythropoietic Effects on Cardiac Function: A Novel Cardiac Myokine

IntroductionErythropoietin (EPO), in response to hypoxia, is produced by the kidney, which stimulates erythropoiesis in the bone marrow. While the kidney is regarded as the primary source of EPO, mainly in vitro expression has been shown from cells or tissues of the brain, liver, and reproductive organs. However, whether these organs are an endogenous extra‐renal source and their physiological significance is unknown. Interestingly, recombinant human EPO (rhEPO) confers cardiac cytoprotection and increases contractility. Albeit, this occurs using supra‐physiological doses of rhEPO. Whether the kidney is responsible for these effects remains to be elucidated. Therefore, the primary objective of this research is to investigate the physiological relevance of endogenous cardiomyocyte EPO production. We hypothesized that: 1) adult cardiomyoctes are a source of EPO production and 2) the loss of cardiomyocyte EPO expression leads to a decrease in contractility and an increase in susceptibility to ischemia‐reperfusion injury.MethodsCardiomyocyte‐specific deletion of EPO (EPOfl/fl‐CM) was obtained by injecting 8‐week old α‐MHC‐MerCreMer+/−: EPO fl/fl male mice with 20 mg/kg tamoxifen daily for 5 days. Left ventricular (LV) EPO expression was determined using qPCR analysis. Cardiac structure and function were assessed by echocardiography, invasive hemodynamics and the Langendorff, respectively. Hematocrit was measured from blood collected via saphenous vein. Data was obtained 8‐weeks post‐tamoxifen.ResultsParadoxically, EPOfl/fl‐CM mice exhibited a dramatic increase in whole heart EPO expression. Further, cardiac‐derived EPO confers inotropic, lusitropic and hypertrophic effects. Furthermore, in response to ischemia‐reperfusion injury, EPOfl/fl‐CM mice show profound cytoprotection. Importantly, we show that endogenous cardiac‐derived EPO is capable of improving cardiac function without affecting whole body Hct levels.ConclusionThe knock‐out of EPO from the cardiomyocyte leads to a reciprocal increase in LV EPO expression, whereby an alternate cell in the heart is over‐compensating for the loss of cardiomyocyte‐derived EPO. This study furthers our fundamental understanding of EPO biology and establishes it as a novel cardiac myokine, capable of increasing cardiac function and driving hypertrophy.Support or Funding InformationHeart and Stroke FoundationCanadian Institutes of Health Research

Adiponectin Reduces Angiotensin II‐Induced Vascular Hypertrophy by Targeting ROS Formation and Actin Cytoskeleton Remodeling

Background and aimsAdiponectin (APN), an adipocytokine, exerts cardioprotective effects, while angiotensin II (Ang II) plays a critical role in the pathogenesis of hypertrophy of vascular smooth muscle cells (VSMCs) induces hypertension and vascular remodeling. Ang II induces VSMC hypertrophy in part via activation of RhoA/ROCK pathway. In this study, we investigated the molecular mechanisms associated with Ang II‐induced RhoA activation and translocation and the ability of ANP to counteract Ang II‐hypertrophic effect through inhibition of RhoA activation, actin cytoskeleton remolding and reactive oxygen species (ROS) formation.MethodsStudies were carried out using rat aortic tissues and VSMCs. The effect of APN on Ang II‐induced RhoA translocation was assessed by Western blotting (WB) and Immunohistochemistry. Leucine incorporation was used to examine NO effect on Ang II induced hypertrophy. The phosphorylation of cofilin‐2 and ERK1/2 was detected by WB. Moreover, immunohistochemistry was performed on aortic frozen sections to detect ROS, F‐actin and G‐actin levels, RhoA‐Cav 1 co‐localization and eNOS translocation.ResultsAng II‐induced VSMCs hypertrophy was prevented by supplementing APN. The hypertrophic response to Ang II was associated with RhoA translocation to caveolae‐rich membrane, cofilin‐2 and ERK1/2 phosphorylation, in addition to a significant decrease in G/F actin ratio. Moreover, ROS production significantly increased with Ang II treatment as revealed by confocal microscopy. However, these effects were inhibited by APN and caveolae disruption. Taken together, these results suggest that Ang II hypertrophic effect is due, in part, to RhoA translocation to caveolae rich micro‐domains and its downstream effectors which is counteracted by APN.ConclusionThese findings suggest the ability of APN to attenuate Angiotensin II‐induced vascular hypertrophy.

Combination of bone morphogenetic protein 9 and transforming growth factor BETA-1 improves cartilaginous matrix formation by equine chondrocytes in three-dimensional culture

Purpose: Osteoarthritis is not only common in humans, but also highly prevalent in horses. In vitro, chondrocytes are used to study disease processes under controlled conditions and the effects of (new) drugs at the cellular level. Bone morphogenic protein 9 (BMP9) has been shown to be a potent modulator of cartilage development by bovine articular chondrocytes. The hypertrophic effect of BMP9 could be antagonized by a low dose of TGFβ-1. We compared the effects of BMP9 and TGFβ-1 on cartilaginous matrix deposition by equine chondrocytes in pellet culture and hypothesized that BMP9 would synergize with a low dose of TGFβ-1 to preserve the healthy chondrocyte phenotype. Methods: Pellets from healthy equine chondrocytes (P1; n = 2 Shetland Pony donors) were cultured for 28 days with chondrogenic medium alone or supplemented with the following: TGFβ-1-low (0.1 ng/ml), TGFβ-1-standard (10 ng/ml), BMP9 (50ng/ml), combination-low (50 ng/ml BMP9 + 0.1 ng/ml TGFβ-1), combination-standard: (50 ng/ml BMP9 + 10 ng/ml TGFβ-1), or combination-low for one week, followed by TGFβ-1-standard (i.e. Switch group). Bern scoring and collagen type-2 (COL2) staining of histology sections and glycosaminoglycan (GAG) and DNA analsyis were performed at days 7, 21, and 28. Gene expression of chondrogenic markers (aggrecan, collagen type-2, TGFβ-1) and hypertrophic or fibrosis markers (ADAMTS5, collagen type-1, collagen type-3, MMP3, MMP13) were measured at day 7 and 28. Statistical analysis was conducted between TGβ-1-standard and the other groups. Results: Analysis of Safranin-O/Fast-green stained sections demonstrated higher Bern scores for the BMP9-treated groups at all time points (fig.1). At day 7, COL2 staining was stronger for groups that received BMP9. GAG content normalized for DNA was significantly higher for the BMP9 and combination-low group at days 21 and 28. At both time points, aggrecan expression was significantly higher than standard in all groups that received BMP9 during the entire culture period. However, COL2 expression was significantly higher for combination groups only, at day 7. MMP3 was significantly upregulated in the BMP9 and combination-low groups at day 28, whereas MMP13 expression was significantly downregulated in these two groups at the same time point. Conclusions: BMP9 improved matrix deposition by equine chondrocytes based on pellet size, GAG/DNA, and intensity of Safranin-O and COL2 staining. Although the combination of BMP9 with low doses of TGFβ-1 upregulated MMP3 expression, it downregulated the expression of the late hypertrophy marker MMP13 while upregulating aggrecan and COL2 expression. Further analysis of hypertrophy markers and underlying signalling pathways should be considered for a deeper understanding of the observed synergistic effect. Altogether, a combination of BMP9 with a low dose of TGFβ-1 significantly improved chondrogenesis of equine chondrocytes.

Low‐dose Lithium is Associated with Left Ventricular Ejection Fraction in Healthy Young Men but not Women

The impact of lithium (Li) exposure on the cardiovascular system is perplexing, as beneficial, negative, and null effects have been identified. Li is an inhibitor of glycogen‐synthase kinase 3β (GSK3‐β) which has been identified as a possible therapeutic target for cardiovascular disease (CVD) and mental health disorders. While earlier ecological studies suggest that trace amounts of Li may protect against CVD, no study to date has investigated the effects of low‐dose Li exposure on cardiac structure and function in healthy young adults without CVD and whether these associations are sex dependent. The purpose of the present investigation was to examine the association between Li exposure and left ventricular mass (LVM) and function in healthy young adults. This investigation represents a cross‐sectional analysis of the Niagara Longitudinal Heart Study (NLHS) at the midpoint of data collection for 156 participants aged 19 – 25 years. A final sample size of 117 had both valid Li and left ventricular data upon analyses. LVM was indexed to height2.7 (LVMi), ejection fraction (EF), fractional shortening (FS), and stroke volume (SV) were assessed following echocardiography in the parasternal long‐axis view of the left ventricle. Serum Li levels were measured using inductively‐coupled plasma mass spectrometry. Li concentration was significantly associated with EF (r = −0.183, p = 0.05) and ESV (r = 0.197, p = 0.03) among the total sample. Li concentration did not differ when examined by sex (p &gt; 0.05), however LVMi, ESV, EDV, SV, and EF were all significantly higher in males than females (p &lt; 0.05). Li was only significantly correlated with EF in men (r = −0.320, p = 0.02) however no correlation was observed among women (p &gt; 0.05). The novel result of our investigation was naturally occurring concentration of Li is associated with decreased EF in men, but not women, although, there was no significant difference in SV. Further, there was no effect of low‐dose Li on LVMi. This is in contrast to some animal studies which demonstrate long‐term exposure to Li has potent hypertrophic effect on the left ventricle, although, Li concentrations in our sample were considerably lower and fall within a normal physiological range. These findings may result from differential sensitivities of the GSK‐3β receptor to Li in the left ventricle in men and women, although further investigation is required.Support or Funding InformationThis research project is funded by the Canadian Institutes of Health Research (CIHR #s 363774, 399332). KSD is funded by a CIHR Doctoral Research Award – Frederick Banting and Charles Best Canada Graduate Scholarship (RFN#167014). VAF is supported by a Brock Explore Grant and an NSERC Discovery Grant (2019‐05833).

A new protein curbs the hypertrophic effect of myostatin inhibition, adding remarkable endurance to motor performance in mice.

Current efforts to improve muscle performance are focused on muscle trophism via inhibition of the myostatin pathway: however they have been unsuccessful in the clinic to date. In this study, a novel protein has been created by combining the soluble activin receptor, a strong myostatin inhibitor, to the C-terminal agrin nLG3 domain (ActR-Fc-nLG3) involved in the development and maintenance of neuromuscular junctions. Both domains are connected via the constant region of an Igg1 monoclonal antibody. Surprisingly, young male mice treated with ActR-Fc-nLG3 showed a remarkably increased endurance in the rotarod test, significantly longer than the single domain compounds ActR-Fc and Fc-nLG3 treated animals. This increase in endurance was accompanied by only a moderate increase in body weights and wet muscle weights of ActR-Fc-nLG3 treated animals and were lower than expected. The myostatin inhibitor ActR-Fc induced, as expected, a highly significant increase in body and muscle weights compared to control animals and ActR-Fc-nLG3 treated animals. Moreover, the prolonged endurance effect was not observed when ActR-Fc and Fc-nLG3 were dosed simultaneously as a mixture and the body and muscle weights of these animals were very similar to ActR-Fc treated animals, indicating that both domains need to be on one molecule. Muscle morphology induced by ActR-Fc-nLG3 did not appear to be changed however, close examination of the neuromuscular junction showed significantly increased acetylcholine receptor surface area for ActR-Fc-nLG3 treated animals compared to controls. This result is consistent with published observations that endurance training in rats increased acetylcholine receptor quantity at neuromuscular junctions and provide evidence that improving nerve-muscle interaction could be an important factor for sustaining long term muscle activity.

Hepatic vein embolization after portal vein embolization to induce additional liver hypertrophy in patients with metastatic colorectal carcinoma.

To assess the effect of salvage hepatic vein embolization (HVE) on the volume of the future liver remnant (FLR) for patients with metastatic colorectal cancer (mCRC) and inadequate hypertrophy following initial portal vein embolization (PVE). From April 2011 to October 2018, 9 patients with mCRC underwent HVE following PVE. The right or middle hepatic vein was embolized with coils and/or vascular plugs. Liver volumes were calculated at baseline, following PVE, and following HVE, in order to assess the hypertrophic effect of PVE and HVE on the FLR. Nine patients underwent HVE (n = 3, right HVE; n = 6, middle HVE) because of inadequate FLR hypertrophy following PVE. The standardized FLR increased from 0.16 (median, range 0.08-0.24) at baseline to 0.22 (median, range 0.13-0.29) following PVE (p= 0.0005) to 0.26 (median, range 0.19-0.37) following HVE (p= 0.0050). HVE was performed 40days (median, range 19-128days) following PVE, and assessment of FLR hypertrophy was performed 41days (median, range 19-92days) following HVE. Four of nine patients underwent hepatectomy; 5 patients failed to undergo hepatectomy (n = 3, inadequate hypertrophy; n = 1, disease progression; n = 1, portal hypertension). One patient required repeat HVE due to a patent accessory vein. Salvage HVE is an effective technique to induce additional FLR hypertrophy in patients with mCRC and inadequate FLR after initial PVE. • Hepatic vein embolization is effective to induce additional liver hypertrophy in surgical patients with metastatic colorectal carcinoma and inadequate hypertrophy after portal vein embolization. • Increases in future liver remnant volume are feasible in patients who receive hepatotoxic neoadjuvant systemic therapy for metastatic colorectal carcinoma. • Sequential portal vein embolization and hepatic vein embolization can be a viable technique to induce liver hypertrophy in patients with small baseline future liver remnant volumes (< 20%).

Combination of low intensity electromagnetic field with chondrogenic agent induces chondrogenesis in mesenchymal stem cells with minimal hypertrophic side effects

ABSTRACTBackground: There are different methods to develop in vitro neo-chondral tissues from adipose-derived stem cells (ADSCs). Application of electromagnetic field (EMF) on ADSCs is one of popular approaches, which results in chondrogenesis. If chondrogenic impact of EMF on ADSCs is supposed to be generalized as a protocol in translational medicine field, possible emergence of early or late hypertrophic maturation, mineralization and inflammatory side effects in chondrogenically differentiating ADSCs should be considered.Methods: The advent of chondrogenic and hypertrophic markers by differentiated cells under standard, platelet-rich plasma (PRP)-based or EMF treatments were monitored. Along with monitoring the expressions of chondrogenic markers, inflammatory and hypertrophic markers, VEGF/TNFα secretion, calcium deposition and ALP activity were evaluated.Results: Accordingly, treatment with %5 PRP results in higher GAG production, enhanced SOX9 transcription, lowered TNFα and VEGF secretions compared to other treatments. Although PRP up-regulates miR-146a and miR-199a in early and late stages of chondrogenesis, respectively, application of EMF + PRP down regulates miR-101 and -145 while up-regulates miR-140 and SOX9 expression.Conclusion: Comparing our results with previous reports suggests that presented EMF-ELF in this study with f = 50 Hz, EMF intensity of less than 30 mT, and 5% PRP (v/v), would facilitate chondrogenesis via mesenchymal stem cells with minor inflammation and hypertrophic maturation.Abbreviations: MSCs: mesenchymal stem cells; TGFβ: transforming growth factor-beta; PRP: platelet-rich plasma; ELF-EMF: extremely low-frequency electromagnetic fields; GAGs: glycosaminoglycans; ADSCs: adipose-derived stem cells; VEGF: vascular endothelial growth factor; TNFα: tumor necrosis factor alpha; ALP: alkaline phosphatase

Beef extract supplementation promotes myoblast proliferation and myotube growth in C2C12 cells.

We previously determined that the intake of beef extract for 4weeks increases skeletal muscle mass in rats. Thus, this study aimed to clarify whether beef extract has a hypertrophic effect on muscle cells and to determine the signaling pathway underlying beef extract-induced myotube hypertrophy. We assessed the effects of beef extract supplement on mouse C2C12 skeletal muscle cell proliferation and differentiation and myotube growth. In addition, the phosphorylation of Akt, ERK1/2, and mTOR following beef extract supplementation was examined by western blotting. Furthermore, the bioactive constituents of beef extract were examined using amino acid analysis and dialysis. In the proliferative stage, beef extract significantly increased myoblast proliferation. In the differentiation stage, beef extract supplementation did not promote myoblast differentiation. In mature myotubes, beef extract supplementation increased myotube diameter and promoted protein synthesis. Although Akt and ERK1/2 levels were not affected, beef extract supplementation increased mTOR phosphorylation, which indicated that the mTOR pathway mediates beef extract-induced myotube hypertrophy. The hypertrophic activity was observed in fractions of > 7000Da. Beef extract promoted C2C12 myoblast proliferation and C2C12 myotube hypertrophy. Myotube hypertrophy was potentially induced by mTOR activation and active components in beef extract were estimated to be > 7000Da.

Glucocorticoids counteract hypertrophic effects of myostatin inhibition in dystrophic muscle.

Duchenne muscular dystrophy (DMD) is a devastating genetic muscle disease resulting in progressive muscle degeneration and wasting. Glucocorticoids, specifically prednisone/prednisolone and deflazacort, are commonly used by DMD patients. Emerging DMD therapeutics include those targeting the muscle-wasting factor, myostatin (Mstn). The aim of this study was to investigate how chronic glucocorticoid treatment impacts the efficacy of Mstn inhibition in the D2.mdx mouse model of DMD. We report that chronic treatment of dystrophic mice with prednisolone (Pred) causes significant muscle wasting, entailing both activation of the ubiquitin-proteasome degradation pathway and inhibition of muscle protein synthesis. Combining Pred with Mstn inhibition, using a modified Mstn propeptide (dnMstn), completely abrogates the muscle hypertrophic effects of Mstn inhibition independently of Mstn expression or SMAD3 activation. Transcriptomic analysis identified that combining Pred with dnMstn treatment affects gene expression profiles associated with inflammation, metabolism, and fibrosis. Additionally, we demonstrate that Pred-induced muscle atrophy is not prevented by Mstn ablation. Therefore, glucocorticoids interfere with potential muscle mass benefits associated with targeting Mstn, and the ramifications of glucocorticoid use should be a consideration during clinical trial design for DMD therapeutics. These results have significant implications for past and future Mstn inhibition trials in DMD.

Short-term angiotensin II treatment regulates cardiac nanomechanics via microtubule modifications.

Mechanical properties of single myocytes contribute to the whole heart performance, but the measurement of mechanics in living cells at high resolution with minimal force interaction remains challenging. Angiotensin II (AngII) is a peptide hormone that regulates a number of physiological functions, including heart performance. It has also been shown to contribute to cell mechanics by inducing cell stiffening. Using non-contact high-resolution Scanning Ion Conductance Microscopy (SICM), we determine simultaneously cell topography and membrane transverse Young's modulus (YM) by a constant pressure application through a nanopipette. While applying pressure, the vertical position is recorded and a deformation map is generated from which YM can be calculated and corrected for the uneven geometry. High resolution of this method also allows studying specific membrane subdomains, such as Z-grooves and crests. We found that short-term AngII treatment reduces the transversal YM in isolated adult rat cardiomyocytes acting via an AT1 receptor. Blocking either a TGF-β1 receptor or Rho kinase abolishes this effect. Analysis of the cytoskeleton showed that AngII depletes microtubules by decreasing long-lived detyrosinated and acetylated microtubule populations. Interestingly, in the failing cardiomyocytes, which are stiffer than controls, the short-term AngII treatment also reduces the YM, thus normalizing the mechanical state of cells. This suggests that the short-term softening effect of AngII on cardiac cells is opposite to the well-characterized long-term hypertrophic effect. In conclusion, we generate a precise nanoscale indication map of location-specific transverse cortical YM within the cell and this can substantially advance our understanding of cellular mechanics in a physiological environment, for example in isolated cardiac myocytes.