Explore the vast range of titles available.

Athletes use creatine monohydrate (CM) to enhance high‐intensity exercise performance by increasing creatine phosphate availability. While CM supplementation is known to raise muscle creatine levels in vegans and vegetarians, its impact on exercise performance remains uncertain. We examined the effects of CM supplementation on muscle creatine content and exercise performance in vegans and vegetarians. In a randomized, double‐blind placebo‐controlled design, 15 healthy vegans and vegetarians consumed CM (0.3 g/kg/day, n = 7) or placebo (PLA, 0.3 g maltodextrin/kg/day, n = 8) four times a day for 7 days. Before and after supplementation, repeated sprint capacity was determined. Body mass and fat‐free mass (FFM) were assessed by dual‐energy x‐ray absorptiometry. The CM group increased body mass (1.56 ± 0.57 kg, p < 0.01) and FFM (1.15 ± 0.94 kg, p < 0.05), while the PLA group showed no changes. In the CM group, muscle creatine (Cr) and total muscle creatine (TCr) increased by 18.8 ± 13.1 mmol/kg (p < 0.05) and 30.8 ± 21.2 mmol/kg (p < 0.01), respectively. The PLA group showed no changes in Cr and TCr (−4.6 ± 13.1 mmol/kg and 2.9 ± 11.6 mmol/kg, respectively). Phosphocreatine levels remained consistent within and between groups. There were no observed changes in peak and mean power output during repeated sprints. A seven‐day CM supplementation in healthy vegans and vegetarians increased Cr and TCr whereas Phosphocreatine, peak and mean power output during repeated sprints was unchanged.

Duchenne muscular dystrophy (DMD) is characterized by progressive muscle weakness and wasting due to the lack of dystrophin protein. The acute phase of DMD is characterized by muscle necrosis and increased levels of the pro-inflammatory mediator, prostaglandin D2 (PGD2). Inhibiting the production of PGD2 by inhibiting hematopoietic prostaglandin D synthase (HPGDS) may alleviate inflammation and decrease muscle necrosis. We tested our novel HPGDS inhibitor, PK007, in the mdx mouse model of DMD. Our results show that hindlimb grip strength was two-fold greater in the PK007-treated mdx group, compared to untreated mdx mice, and displayed similar muscle strength to strain control mice (C57BL/10ScSn). Histological analyses showed a decreased percentage of regenerating muscle fibers (~20% less) in tibialis anterior (TA) and gastrocnemius muscles and reduced fibrosis in the TA muscle in PK007-treated mice. Lastly, we confirmed that the DMD blood biomarker, muscle creatine kinase activity, was also reduced by ~50% in PK007-treated mdx mice. We conclude that our HPGDS inhibitor, PK007, has effectively reduced muscle inflammation and fibrosis in a DMD mdx mouse model.

Objective: This study aims to investigate the interactive effect of a glycine equivalent (Glyequi) and standardized ileal digestible threonine (SID Thr) levels in low crude protein diets on performance, blood biochemistry, pectoral muscular creatine content and oxidative stability of meat in broiler chickens from 21 to 42 days.Methods: A total of 1,500, twenty-one-day-old Cobb-Vantress male broiler chickens were distributed in a completely randomized 5×3 factorial arrangement of Glyequi×SID Thr with five replicates of 20 birds each. Fifteen dietary treatments of 16.5% CP were formulated to contain five levels of total Glyequi (1.16%, 1.26%, 1.36%, 1.46%, and 1.56%) and three levels of SID Thr (0.58%; 0.68% and 0.78%).Results: Interaction effects (p<0.05) of Glyequi and SID Thr levels were observed for weight gain, carcass yield, pectoral muscular creatine content and serum uric acid. Higher levels of Glyequi increased (p = 0.040) weight gain in 0.58% and 0.68% SID Thr diets compare to the 0.78% SID Thr diet. The SID Thr level at 0.68% improved (p = 0.040) feed conversion compared to other SID Thr diets. Levels of Glyequi equal to or above 1.26% in diets with 0.78% SID Thr resulted in birds with higher (p = 0.033) pectoral muscular creatine content. The breast meat yield observed in the 0.68% SID Thr diet was higher (p = 0.05) compared to the 0.58% SID Thr diet. There was a quadratic effect of Glyequi levels for pectoral pectoral muscular creatine content (p = 0.008), breast meat yield (p = 0.030), and serum total protein concentrations (p = 0.040), and the optimal levels were estimated to be 1.47%, 1.35%, and 1.40% Glyequi, respectively. The lowest (p = 0.050) concentration of malondialdehyde in the breast meat was found in 0.68% SID Thr diets at 1.36% Glyequi. Conclusion: The minimum dietary level of Glyequi needed to improve performance in low crude protein diets is 1.26% with adequate SID Thr levels for broiler chickens.

Protein kinase C (PKC) is an important signaling molecule in the heart, but its targets remain unclear. Using a PKC substrate antibody, we detected a 40-kDa phosphorylated cardiac protein that was subsequently identified by tandem mass spectroscopy as muscle creatine kinase (M-CK) with phosphorylation at serine 128. The forward reaction using ATP to generate phosphocreatine was reduced, while the reverse reaction using phosphocreatine to generate ATP was increased following dephosphorylation of immunoprecipitated M-CK with protein phosphatase 2A (PP2A) or PP2C. Despite higher PKC levels in diabetic hearts, decreased phosphorylation of M-CK was more prominent than the reduction in its expression. Changes in CK activity in diabetic hearts were similar to those found following dephosphorylation of M-CK from control hearts. The decrease in phosphorylation may act as a compensatory mechanism to maintain CK activity at an appropriate level for cytosolic ATP regeneration in the diabetic heart.

Introduction/ObjectivesArticular cartilage and periarticular muscle tissues are strongly affected during knee osteoarthritis (OA). Creatine kinase (CK) is an enzyme expressed in several tissues, but the isoform CK-MM is specific of skeletal muscle, and its serum concentration is used as a biomarker of muscle damage. Genetic variants of the CKM gene have been associated with various pathologies, but to date, there are no reports of association with OA. Due to the rs4884 polymorphism being well represented in the Mexican population, it is used as an ancestry informative marker; thus, the goal of this preliminary report was to evaluate the association of this polymorphism in primary knee OA Mexican patients.MethodEighty-seven patients with primary knee OA were compared with 107 healthy controls. Serum CK-MM was determined using the dot blot system, and genotyping was performed using the OpenArray system. Logistic regression models were used to assess the association between the rs4884 polymorphism and OA susceptibility adjusting by gender, age, and body mass index.ResultsThere were no significant differences in serum CK-MM values between patients and controls. The GG genotype and the G allele had a higher frequency in the control group compared with the OA group (24.3% vs. 12.6%, OR = 0.34, 95% CI = 0.14–0.84, P = 0.019; and 40.2% vs. 28.2%, OR = 0.51, 95% CI = 0.32–0.82, P = 0.005, respectively).ConclusionsOur results suggest a protection role of the rs4884 polymorphism against knee OA development; further studies are required to confirm it.Key Points• CK-MM enzyme catalyzes the conversion of creatine and ATP to create phosphocreatine and ADP; this reaction is reversible.• In tissues that consume ATP rapidly, such as skeletal muscle, the phosphocreatine serves as an important energy reservoir.• During knee OA, peripheral muscle tissues of the joint may be affected.• The rs4884 polymorphism of the CKM gene may participate as a protective factor in the development of OA.

Background Extracts of Russian Tarragon (RT) have been reported to produce anti-hyperglycemic effects and influence plasma creatine (Cr) levels while supplementing with creatine monohydrate (CrM). The purpose of this preliminary study was to determine if short-term, low-dose aqueous RT extract ingestion prior to CrM supplementation influences whole body Cr retention, muscle Cr or measures of anaerobic sprint performance. Methods In a double-blind, randomized, and crossover manner; 10 recreationally trained males (20 ± 2 yrs; 179 ± 9 cm; 91.3 ± 34 kg) ingested 500 mg of aqueous RT extract ( Finzelberg, Andernach, Germany ) or 500 mg placebo 30-minutes prior to ingesting 5 g of CrM ( Creapure®, AlzChem AG, Germany ) twice per day for 5-days then repeated after a 6-week wash-out period. Urine was collected at baseline and during each of the 5-days of supplementation to determine urine Cr content. Whole body Cr retention was estimated from urine samples. Muscle biopsies were obtained for determination of muscle free Cr content. Participants also performed two 30-second Wingate anaerobic capacity tests prior to and following supplementation for determination of peak power (PP), mean power (MP), and total work (TW). Data were analysed by repeated measures MANOVA. Results Whole body daily Cr retention increased in both groups following supplementation (0.0 ± 0.0; 8.2 ± 1.4, 6.5 ± 2.4, 5.6 ± 3.2, 6.1 ± 2.6, 4.8 ± 3.2 g · d -1 ; p = 0.001) with no differences observed between groups (p = 0.59). After 3 and 5-days of supplementation, respectively, both supplementation protocols demonstrated a significant increase in muscle free Cr content from baseline (4.8 ± 16.7, 15.5 ± 23.6 mmol · kg -1 DW, p = 0.01) with no significant differences observed between groups (p = 0.34). Absolute change in MP (9 ± 57, 35 ± 57 W; p = 0.031), percent change in MP (2.5 ± 10.5, 6.7 ± 10.4%; p = 0.026), absolute change in TW (275 ± 1,700, 1,031 ± 1,721 J; p = 0.032), and percent change in TW (2.5 ± 10.5, 6.6 ± 10.4%; p = 0.027) increased over time in both groups with no differences observed between groups. Conclusions Short-term CrM supplementation (10 g · d -1 for 5-days) significantly increased whole body Cr retention and muscle free Cr content. However, ingesting 500 mg of RT 30-min prior to CrM supplementation did not affect whole body Cr retention, muscle free Cr content, or anaerobic sprint capacity in comparison to ingesting CrM with a placebo.

Background Congenital heart disease is a leading cause of death in newborns and infants. The feasibility of fetal cardiac surgery is linked to extracorporeal circulation (ECC); therefore, cardioplegic solutions need to be effective and long-lasting. Methods Eighteen pregnant sheep were divided into an ECC-only group, St. Thomas’ Hospital cardioplegic solution (STH1) group (STH group), and HTK preservation solution (Custodiol®) group (HTK group). Markers of myocardial injury including troponin I (cTnI), troponin T (cTnT) and creatine kinase myocardial band (CKMB) were measured at specific time points (T1: pre-ECC, T2: 30 min of ECC, T3: 60 min of ECC, T4: 60 min post-ECC, T5: 120 min post-ECC). Myocardial tissue was removed from the fetal sheep at T5, and apoptosis was detected by TUNEL staining. Results Changes in the serum cTnI, cTnT and CKMB concentrations were not significantly different among the three groups before and during the ECC(T1,T2,T3). At 60 min after ECC shutdown(T4), cTnI and cTnT concentrations were significantly higher in the STH group than before the start of ECC. The concentration of cTnI was higher in the STH group than in the HTK and ECC-only groups. The concentration of cTnT was higher in the STH group than in the ECC-only group. At 120 min after ECC shutdown(T5), cTnI and cTnT concentrations were significantly higher in the ECC and HTK groups than before the start of ECC, and CKMB concentration was significantly higher in STH and HTK groups. The concentrations of cTnT, cTnI and CKMB was higher in the STH group than in the HTK and ECC-only groups. The number of TUNEL-positive cells in the HTK and STH groups was higher than in the ECC-only group. The number of TUNEL-positive cells in the STH group was higher than in the HTK group. There was no statistically significant difference among the groups in the heart rate and mean arterial pressure after ECC. Conclusion The HTK preservation solution was significantly better than STH1 in reducing the release of cardiomyocyte injury markers and the number of apoptotic cells in fetal sheep ECC. Fetal sheep receiving ECC-only had an advantage in all indicators, which suggests ECC-only fetal heart surgery is feasible.

Exertional rhabdomyolysis (ER) occurs in young, otherwise healthy, individuals principally during strenuous exercise, athletic, and military training. Although many risk factors have been offered, it is unclear why some individuals develop ER when participating in comparable levels of physical exertion under identical environmental conditions and others do not. This study investigated possible genetic polymorphisms that might help explain ER. DNA samples derived from a laboratory-based study of persons who had never experienced an episode of ER (controls) and clinical ER cases referred for testing over the past several years were analyzed for single nucleotide polymorphisms (SNPs) in candidate genes. These included angiotensin I converting enzyme ( ACE ), α-actinin-3 ( ACTN3 ), creatine kinase muscle isoform ( CKMM ), heat shock protein A1B ( HSPA1B ), interleukin 6 ( IL6 ), myosin light chain kinase ( MYLK ), adenosine monophosphate deaminase 1 ( AMPD1 ), and sickle cell trait ( HbS ). Population included 134 controls and 47 ER cases. The majority of ER cases were men ( n  = 42/47, 89.4 %); the five women with ER were Caucasian. Eighteen African Americans (56.3 %) were ER cases. Three SNPs were associated with ER: CKMM Nco l, ACTN3 R577X, and MYLK C37885A. ER cases were 3.1 times more likely to have the GG genotype of CKMM (odds ratio/OR = 3.1, confidence interval/CI 1.33–7.10), 3.0 times for the XX genotype of ACTN3 SNP (OR = 2.97, CI 1.30–3.37), and 5.7 times for an A allele of MYLK (OR = 21.35, CI 2.60–12.30). All persons with HbS were also ER cases. Three distinct polymorphisms were associated with ER. Further work will be required to replicate these findings and determine the mechanism(s) whereby these variants might confer susceptibility.

Creatine plays an important role in the cell as an energy buffer. As the energy system is a basic element of the organism it may possibly contribute to differences between rainbow trout strains selected for the traits growth and robustness, respectively. The cDNA sequences of creatine-related genes encoding glycine amidinotransferase ( GATM ), guanidinoacetate N-methyltransferase ( GAMT ), creatine kinase muscle-type ( CKM) and creatine transporter 1 (CT1, encoded by gene solute carrier family 6, member 8 ( SLC6A8 )) were characterized in rainbow trout. Transcripts of the respective genes were quantified in kidney, liver, brain and skeletal muscle in both trout strains that had been acclimated to different temperatures. Several differences between the compared trout strains were found as well as between temperatures indicating that the energy system may contribute to differences between both strains. In addition to that, the expression data showed clear differences between the creatine system in rainbow trout and mammals, as the spatial distribution of the enzyme-encoding gene expression was clearly different from the patterns described for mammals. In rainbow trout, creatine synthesis seems to take place to a big extent in the skeletal muscle.

Adenoviral gene transfer holds promise for gene therapy, but effective transduction of a large and distributed tissue such as muscle will almost certainly require systemic delivery. In this context, the use of muscle-specific regulatory elements such as the muscle creatine kinase (MCK) promoter and enhancer will avoid potentially harmful ectopic expression of transgenes. We describe here the development and testing of adenoviral vectors containing small, striated muscle-specific, highly active MCK expression cassettes. One of these regulatory elements (CK6) is less than 600 bp in length and is 12% as active as the CMV promoter/enhancer in muscle. A recombinant adenoviral vector containing this regulatory element retains very high muscle specificity, expressing 600-fold higher levels of transgene in muscle than in liver. Muscle-specific regulatory elements may also increase persistence of transduced muscle cells. Adenoviral transduction of dendritic cells has been shown to stimulate cytotoxic T-lymphocyte (CTL) responses directed against transgene epitopes. We show that human dendritic cells infected in vitro with MCK-containing adenoviruses do not express significant levels of transgene. Furthermore, while adenoviral vectors containing nonspecific promoters are normally cleared from muscle tissue within 1 month, we show that MCK-containing vectors express significant levels of transgene 4 months after intramuscular injection.