Consumption of New Zealand Blackcurrant Extract Improves Recovery from Exercise-Induced Muscle Damage in Non-Resistance Trained Men and Women: A Double-Blind Randomised Trial.

BACKGROUND: Blackcurrant is rich in anthocyanins that may protect against exercise-induced muscle damage (EIMD) and facilitate a faster recovery of muscle function. We examined the effects of New Zealand blackcurrant (NZBC) extract on indices of muscle damage and recovery following a bout of strenuous isokinetic resistance exercise. METHODS: Using a double-blind, randomised, placebo controlled, parallel design, twenty-seven healthy participants received either a 3 g·day-1 NZBC extract (n = 14) or the placebo (PLA) (n = 13) for 8 days prior to and 4 days following 60 strenuous concentric and eccentric contractions of the biceps brachii muscle on an isokinetic dynamometer. Muscle soreness (using a visual analogue scale), maximal voluntary contraction (MVC), range of motion (ROM) and blood creatine kinase (CK) were assessed before (0 h) and after (24, 48, 72 and 96 h) exercise. RESULTS: Consumption of NZBC extract resulted in faster recovery of baseline MVC (p = 0.04), attenuated muscle soreness at 24 h (NZBC: 21 ± 10 mm vs. PLA: 40 ± 23 mm, p = 0.02) and 48 h (NZBC: 22 ± 17 vs. PLA: 44 ± 26 mm, p = 0.03) and serum CK concentration at 96 h (NZBC: 635 ± 921 UL vs. PLA: 4021 ± 4319 UL, p = 0.04) following EIMD. CONCLUSIONS: Consumption of NZBC extract prior to and following a bout of eccentric exercise attenuates muscle damage and improves functional recovery. These findings are of practical importance in recreationally active and potentially athletic populations, who may benefit from accelerated recovery following EIMD.

Association between Muscle Damage and Head Impacts in High School American Football.

Subconcussive head impacts (SHI), defined as impacts to the cranium that do not result in concussion symptoms, are gaining traction as a major public health concern. The contribution of physiological factors such as physical exertion and muscle damage to SHI-dependent changes in neurological measures remains unknown. A prospective longitudinal study examined the association between physiological factors and SHI kinematics in 15 high school American football players over one season. Players wore a sensor-installed mouthguard for all practices and games, recording frequency and magnitude of all head impacts. Serum samples were collected at 12 time points (pre-season, pre- and post-game for five in-season games, and post-season) and were assessed for an isoenzyme of creatine kinase (CK-MM) primarily found in skeletal muscle. Physical exertion was estimated in the form of excess post-exercise oxygen consumption (EPOC) from heart rate data captured during the five games. Mixed-effect regression models indicated that head impact kinematics were significantly and positively associated with change in CK-MM but not EPOC. There was a significant and positive association between CK-MM and EPOC. These data suggest that when examining SHI, effects of skeletal muscle damage should be considered when using outcome measures that may have an interaction with muscle damage.

The Effect of High-Dose Vitamin C on Biochemical Markers of Myocardial Injury in Coronary Artery Bypass Surgery.

OBJECTIVE: To evaluate the effect of high-dose vitamin C on cardiac reperfusion injury and plasma levels of creatine kinase-muscle/brain (CK-MB), troponin I, and lactate dehydrogenase (LDH) in patients undergoing coronary artery bypass grafting (CABG). METHODS: This is a double-blind randomized clinical trial study. Fifty patients (50-80 years old) who had CABG surgery were selected. The intervention group received 5 g of intravenous vitamin C before anesthesia induction and 5 g of vitamin C in cardioplegic solution. The control group received the same amount of placebo (normal saline). Arterial blood samples were taken to determine the serum levels of CK-MB, troponin I, and LDH enzymes. Left ventricular ejection fraction was measured and hemodynamic parameters were recorded at intervals. RESULTS: High doses of vitamin C in the treatment group led to improvement of ventricular function (ejection fraction [EF]) and low Intensive Care Unit (ICU) stay. The cardiac enzymes level in the vitamin C group was lower than in the control group. These changes were not significant between the groups in different time intervals (anesthesia induction, end of bypass, 6 h after surgery, and 24 h after surgery) for CK-MB, LDH, and troponin I. Hemodynamic parameters, hematocrit, potassium, urinary output, blood transfusion, arrhythmia, and inotropic support showed no significant difference between the groups. CONCLUSION: Vitamin C has significantly improved the patients' ventricular function (EF) 72 h after surgery and reduced the length of ICU stay. No significant changes in cardiac biomarkers, including CK-MB, troponin I, and LDH, were seen over time in each group. IRCT CODE: IRCT2016053019470N33.

The effect of high-dose vitamin c on biochemical markers of myocardial injury in coronary artery bypass surgery

Abstract Objective: To evaluate the effect of high-dose vitamin C on cardiac reperfusion injury and plasma levels of creatine kinase-muscle/brain (CK-MB), troponin I, and lactate dehydrogenase (LDH) in patients undergoing coronary artery bypass grafting (CABG). Methods: This is a double-blind randomized clinical trial study. Fifty patients (50-80 years old) who had CABG surgery were selected. The intervention group received 5 g of intravenous vitamin C before anesthesia induction and 5 g of vitamin C in cardioplegic solution. The control group received the same amount of placebo (normal saline). Arterial blood samples were taken to determine the serum levels of CK-MB, troponin I, and LDH enzymes. Left ventricular ejection fraction was measured and hemodynamic parameters were recorded at intervals. Results: High doses of vitamin C in the treatment group led to improvement of ventricular function (ejection fraction [EF]) and low Intensive Care Unit (ICU) stay. The cardiac enzymes level in the vitamin C group was lower than in the control group. These changes were not significant between the groups in different time intervals (anesthesia induction, end of bypass, 6 h after surgery, and 24 h after surgery) for CK-MB, LDH, and troponin I. Hemodynamic parameters, hematocrit, potassium, urinary output, blood transfusion, arrhythmia, and inotropic support showed no significant difference between the groups. Conclusion: Vitamin C has significantly improved the patients' ventricular function (EF) 72 h after surgery and reduced the length of ICU stay. No significant changes in cardiac biomarkers, including CK-MB, troponin I, and LDH, were seen over time in each group. IRCT code: IRCT2016053019470N33

A Performance Evaluation of Liver and Skeletal Muscle-Specific miRNAs in Rat Plasma to Detect Drug-Induced Injury.

Liver and skeletal muscle-specific microRNAs (miRNAs) are currently being evaluated as novel plasma biomarkers that may out-perform or add value to the conventional liver injury biomarkers alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and to the skeletal muscle injury biomarkers AST and creatine kinase (CK). A comprehensive evaluation was conducted to assess the relative performance of these miRNAs to detect and distinguish liver from muscle tissue injury. The performance of miR-122 and miR-192 for liver and miR-1, miR-133a, miR-133b, and miR-206 for skeletal muscle was compared with 10 enzymatic or protein biomarkers across 27 compounds causing specific types of tissue injury in rat. Receiver operator characteristic analyses were performed comparing the relative sensitivity and specificity of each of the biomarkers in individual animals with histopathology observations of necrosis and/or degeneration in various organs. All of the miRNAs outperformed ALT, AST, and/or CK in studies with either liver or skeletal muscle injury and demonstrated superior specificity in organs without type-specific injury (eg, liver biomarkers assessed with compounds that cause skeletal muscle injury). When additional protein biomarkers were included, glutamate dehydrogenase, arginase I, alpha-glutathione S-transferase for liver and skeletal troponin I, myosin light chain 3, fatty acid-binding protein 3, and creatine kinase M isoform for skeletal muscle, the miRNAs demonstrated equal or superior performance to the extended panel. Taken together, this comprehensive evaluation demonstrates that these novel miRNA toxicity biomarkers outperform and add value with respect to sensitivity and specificity over ALT, AST in monitoring the liver and over CK for monitoring skeletal muscle drug-induced injury.

A novel rabbit model of Duchenne muscular dystrophy generated by CRISPR/Cas9.

Duchenne muscular dystrophy (DMD) is an X-linked muscle-wasting disorder caused by mutations in the dystrophin gene, with an incidence of 1 in 3500 in new male births. Mdx mice are widely used as an animal model for DMD. However, these mice do not faithfully recapitulate DMD patients in many aspects, rendering the preclinical findings in this model questionable. Although larger animal models of DMD, such as dogs and pigs, have been generated, usage of these animals is expensive and only limited to several facilities in the world. Here, we report the generation of a rabbit model of DMD by co-injection of Cas9 mRNA and sgRNA targeting exon 51 into rabbit zygotes. The DMD knockout (KO) rabbits exhibit the typical phenotypes of DMD, including severely impaired physical activity, elevated serum creatine kinase levels, and progressive muscle necrosis and fibrosis. Moreover, clear pathology was also observed in the diaphragm and heart at 5 months of age, similar to DMD patients. Echocardiography recording showed that the DMD KO rabbits had chamber dilation with decreased ejection fraction and fraction shortening. In conclusion, this novel rabbit DMD model generated with the CRISPR/Cas9 system mimics the histopathological and functional defects in DMD patients, and could be valuable for preclinical studies.This article has an associated First Person interview with the first author of the paper.

Antipsychotic-induced disorders: Reported cases and prospective study on muscle biomarkers after high exposure to haloperidol.

Antipsychotic drugs are known to induce neuromuscular effects. In this study, we review 13 years (2002-2014) of antipsychotic intoxications reported by the anti-poisoning center of Algiers (APCA). The most recorded symptoms were neuromuscular/muscular disorders, of which haloperidol was the most inducer among all antipsychotics. A prospective study was conducted between December 2012 and January 2017 to evaluate muscle effects generated after intentional or accidental ingestion of haloperidol. Fifty-one patients admitted in different emergency departments in Algiers were included in this study. Urine and blood samples were collected from each patient for biological and toxicological monitoring and a group of healthy volunteers was assessed for comparison purpose. There was no significant difference in plasma lactate dehydrogenase (LDH) activity between healthy volunteers and exposed patients even when high levels of haloperidol were recorded. In contrast, selenium concentration and creatine kinase (CK) activity in plasma samples were significantly higher in patients exposed to high levels of haloperidol compared to healthy volunteers. Large percentage of patients exposed to high levels of haloperidol presented a significant elevated CK activity and high selenium concentration regarding the physiological thresholds. Additionally, CK activity and selenium concentration correlated positively with plasma content of haloperidol suggesting a dose-dependent relationship. In conclusion, some biomarkers (CK and selenium) may reflect muscle adverse effects of high haloperidol exposure that result possibly from muscle rigidity.

Rhabdomyolysis in a Tertiary PICU: A 10-Year Study.

OBJECTIVES: Rhabdomyolysis is a disorder of muscle breakdown. The aim of this study was to describe the epidemiology of rhabdomyolysis in children admitted to a PICU and to assess the relationship between peak creatinine kinase and mortality. DESIGN: Retrospective cohort study in children admitted to the PICU with rhabdomyolysis between January 1, 2005, and December 31, 2014. Demographic, clinical, and outcome data were recorded. Outcomes were analyzed by level of peak creatinine kinase value (0-10,000, 10,001-50,000, > 50,000IU/L). Long-term renal outcomes were reported for PICU survivors. SETTING: A single-centre academic tertiary PICU. PATIENTS: Children admitted to the PICU with serum creatinine kinase level greater than 1,000 IU/L. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: There were 182 children with rhabdomyolysis. The median peak creatinine kinase value was 3,583 IU/L (1,554-9,608). The primary diagnostic categories included sepsis, trauma, and cardiac arrest. Mortality for peak creatinine kinase values 0-10,000, 10,001-50,000, and > 50,000 IU/L were 24/138 (17%), 6/28 (21%), and 3/16 (19%), respectively (p = 0.87). Children with a peak creatinine kinase greater than 10,000 IU/L had a longer duration of mechanical ventilation and ICU length of stay than children with peak creatinine kinase less than 10,000. Renal replacement therapy was administered in 29/182 (16%). There was longer duration of mechanical ventilation (273 [141-548] vs. 73 [17-206] hr [p < 0.001]) and ICU length of stay (334 [147-618] vs. 100 [37-232] hr (p < 0.001)] in children receiving renal replacement therapy. Continuous veno-venous hemofiltration was the most common modality 23/29 (79%). Only one child required renal replacement therapy postintensive care stay, and adverse long-term renal outcomes were uncommon. CONCLUSIONS: In children with rhabdomyolysis requiring intensive care, peak creatinine kinase was not associated with mortality but is associated with greater use of intensive care resources. Chronic kidney disease is an uncommon sequelae of rhabdomyolysis in children requiring intensive care.

Biochemical stress evaluation after medial parapatellar and subvastus approach in total knee replacement.

INTRODUCTION: Even if different surgical approaches for total knee arthroplasty are well known since decades, the standard medial parapatellar incision remains the most common one; general agreement about significant advantages with minimally invasive techniques is lacking. Furthermore, the surgical stress effect on the organism has always been analyzed through blood inflammatory parameters. This study aim was to compare the standard and subvastus approaches, using the salivary cortisol in particular as measure for systemic surgery-related stress. METHODS: Fifteen operations were performed in a consecutive series; clinical (Knee Society Knee Scoring System., a questionnaire score, range of motion, tourniquet time, intra-operative bleeding) and biochemical factors (salivary and hematic cortisol, C-reactive protein, muscular creatine phosphokinase levels) were evaluated. The final follow-up was at two months after the operation. RESULTS: No significant differences were observed in most of the parameters; however, the subvastus group had a sharper and earlier functional improvement trend than the standard one. On the other side, it increased the CPK levels significantly. CONCLUSIONS: In our experience, the medial subvastus approach, firstly associated with greater surgical stress, has then been characterized by a more favorable functional improvement trend. Moreover, the salivary cortisol measurement has proved to be a non-invasive and reliable method to evaluate the systemic surgery-related stress.

Microscope-assisted anterior cervical discectomy and fusion combined with posterior minimally invasive surgery through tubular retractors for multisegmental cervical spondylotic myelopathy: A retrospective study.

This study aimed to investigate the clinical efficacy and outcome of combined microscope-assisted anterior cervical discectomy and fusion (ACDF) with posterior minimally invasive surgery through tubular retractors for patients with multisegmental cervical spondylotic myelopathy (MCSM).This retrospective study included 28 patients (19 males and 9 females) with multisegmental cervical spondylotic myelopathy, who underwent combined microscope-assisted ACDF with posterior minimally invasive surgery through tubular retractors in our single center between January 2012 and December 2016. The evaluated postoperative clinical outcomes were operation time, length of hospitalization, blood loss, levels of creatine phosphokinase isoenzyme MM (CPK-MM), Japanese Orthopedic Association (JOA) scores, visual analogue scale (VAS) scores, Cobb angle of C2-C7, and radiological assessments (included X-rays, computed tomography scans, and magnetic resonanceimaging images).The mean surgery time was 198.42 ±â€Š17.53 minutes, the average hospitalization length of hospital was 7.59 ±â€Š1.38 days, and the mean follow-up time was 13 ±â€Š2.45 months. On average, about 36.42 ±â€Š10.15 mL of blood was lost and CPK-MM increased to 331.75 ±â€Š23.15 IU/mL postoperatively (P < .001). The mean modified JOA scores increased from 8.21 ±â€Š0.69 preoperatively to 13.96 ±â€Š1.57 postoperatively (P < .001), whereas the mean VAS scores decreased from 6.64 ±â€Š1.28 preoperatively to 0.39 ±â€Š0.50 postoperatively (P < .001). Cobb angle of C2-C7 increased from 13.86°â€Š±â€Š5.69° preoperatively to 14.10°â€Š±â€Š5.56° postoperatively (P = .16).In conclusion, combined microscope-assisted ACDF with posterior minimally invasive surgery through tubular retractors appears to be a safe and effective treatment for patients with MCSM.

Optimum polygenic profile to resist exertional rhabdomyolysis during a marathon.

PURPOSE: Exertional rhabdomyolysis can occur in individuals performing various types of exercise but it is unclear why some individuals develop this condition while others do not. Previous investigations have determined the role of several single nucleotide polymorphisms (SNPs) to explain inter-individual variability of serum creatine kinase (CK) concentrations after exertional muscle damage. However, there has been no research about the interrelationship among these SNPs. The purpose of this investigation was to analyze seven SNPs that are candidates for explaining individual variations of CK response after a marathon competition (ACE = 287bp Ins/Del, ACTN3 = p.R577X, CKMM = NcoI, IGF2 = C13790G, IL6 = 174G>C, MLCK = C37885A, TNFα = 308G>A). METHODS: Using Williams and Folland's model, we determined the total genotype score from the accumulated combination of these seven SNPs for marathoners with a low CK response (n = 36; serum CK <400 U·L-1) vs. marathoners with a high CK response (n = 31; serum CK ≥400 U·L-1). RESULTS: At the end of the race, low CK responders had lower serum CK (290±65 vs. 733±405 U·L-1; P<0.01) and myoglobin concentrations (443±328 vs. 1009±971 ng·mL-1, P<0.01) than high CK responders. Although the groups were similar in age, anthropometric characteristics, running experience and training habits, total genotype score was higher in low CK responders than in high CK responders (5.2±1.4 vs. 4.4±1.7 point, P = 0.02). CONCLUSION: Marathoners with a lower CK response after the race had a more favorable polygenic profile than runners with high serum CK concentrations. This might suggest a significant role of genetic polymorphisms in the levels of exertional muscle damage and rhabdomyolysis. Yet other SNPs, in addition to exercise training, might also play a role in the values of CK after damaging exercise.

Response of Novel Skeletal Muscle Biomarkers in Dogs to Drug-Induced Skeletal Muscle Injury or Sustained Endurance Exercise.

The skeletal muscle (SKM) injury biomarkers, skeletal troponin I (sTnI), myosin light chain 3 (Myl3), and creatine kinase muscle isoform (Ckm) have been shown recently to be more sensitive and specific for monitoring drug-induced SKM injury than the conventional biomarkers, aspartate transaminase (AST) and creatine kinase (CK) enzymatic assays in rat toxicology studies. To evaluate the utility of these SKM biomarkers across species, they were assessed in 2 dog models: a drug-induced injury study in Beagle dogs and a 160 km endurance exercise run completed by Alaskan sled dogs. In the drug-induced injury model, mean sTnI and Myl3 plasma levels were 6- and 18-fold, respectively, compared with baseline as early as Study Day (SD) 15, while mean plasma AST and CK levels did not increase, and biopsy samples were non-remarkable for histopathology prior to SD 29 when degeneration was first noted. Peak group mean plasma responses over baseline for sTnI, Myl3, and Ckm biomarkers were 96-, 103-, and 11-fold, respectively, compared with 2.5-fold for AST and 3.8-fold for CK-enzymatic (CK-enz) assay. In the sled dog sustained exercise model, the peak response for all biomarkers was observed at the first sampling (2 h) after the completion of the run. The sTnI, Myl3, and Ckm mean fold peak values compared with baseline were 170-, 120-, and 150-fold, respectively, while AST increased 7-fold and CK-enz increased 29-fold. These findings support the conclusion that sTnI, Myl3, and Ckm are sensitive early tissue leakage biomarkers for monitoring SKM injury and effects of exercise in dog, extending their utility across preclinical species beyond the rat, and provide further support to investigate their translational utility to clinical trial settings to monitor for drug-induced SKM injury and ensure patient safety.

Fatty acid binding protein 3 is associated with skeletal muscle strength in polymyositis and dermatomyositis.

OBJECTIVE: To determine serum levels and histopathological characteristics of fatty acid binding protein 3 (FABP3) in patients with polymyositis (PM) and dermatomyositis (DM), and to evaluate the correlation between the FABP3 and muscle strength. METHODS: The study population included 24 subjects with PM/DM, 12 subjects with asymptomatic or minimally symptomatic hyper-creatine kinase-emia (AMSH), and 10 healthy control subjects. Muscle strength was measured by using the Manual Muscle Test (MMT8). Serum CK, myoglobin and FABP3 levels were tested. Correlations between variables were studied by using Spearman's rank and partial correlation analysis methods. Immunohistochemical and double immunofluorescent stainings of FABP3 were performed to investigate its distribution in skeletal muscle. RESULTS: PM/DM patients had significantly higher (P < 0.05) serum FABP3 levels (35.46 ± 38.45 ng/mL) than did AMSH patients (3.77 ± 1.21 ng/mL) and healthy control subjects (4.30 ± 3.18 ng/mL). MMT8 scores correlated negatively with CK, myoglobin and FABP3 levels. Partial correlation analysis was performed and showed that the correlation coefficients between MMT8 score and serum CK, myoglobin and FABP3 levels were -0.276 (P > 0.05), -0.228 (P > 0.05) and -0.927 (P < 0.001), respectively. Immunohistochemical and double immunofluorescent staining showed that FABP3 expression increased in the skeletal muscle of PM/DM patients and was mainly distributed in slow twitch muscle fibers. CONCLUSION: Serum levels of FABP3 in PM/DM patients were significantly increased and were mainly distributed in slow twitch muscle fibers, displaying a closer association with muscle weakness than did serum levels of CK and myoglobin. FABP3 is likely to be a useful serum biomarker in PM/DM patients.

Cardiovascular function is not associated with creatine kinase activity in a black African population: The SABPA study.

BACKGROUND: Higher creatine kinase (CK) activity is associated with the development of cardiovascular disease in black African populations. We compared CK activity and investigated associations of blood pressure with CK activity in black and white men as well as black and white women. METHODS: Ambulatory blood pressure, total peripheral resistance and pulse wave velocity of 197 black and 208 white participants were determined and serum CK activity was measured. RESULTS: Blood pressure and pulse wave velocity were higher in black men and women (all p < 0.001) when compared to their white counterparts. CK activity only varied between black and white women (75.9 U/l vs 62.8 U/l, p = 0.009), even after adjusting for age, body mass index and physical activity. Despite the worse cardiovascular profile of black men and women, and the higher CK activity in the black women, we were unable to link blood pressure, pulse wave velocity or total peripheral resistance with CK activity, in the black African population. In white men, total peripheral resistance was associated with CK activity (R (2) = 0.32; ß = 0.25; p = 0.009), whereas systolic blood pressure (R (2) = 0.46; ß = 0.17; p = 0.03) and pulse pressure (R (2) = 0.31; ß = 0.21; p = 0.01) were associated with CK activity in white women. CONCLUSIONS: The lack of associations in the black African population suggests that the link between a worse cardiovascular profile and CK activity may be overshadowed by other contributing factors. Whereas, the established link between cardiovascular function and CK activity in the white groups may be the result of enhanced smooth muscle cell contractility and/or attenuated nitric oxide synthesis capacity.

Musculoskeletal pain in patients with chronic kidney disease. / Dolor músculo-esquelético en pacientes con enfermedad renal crónica.

INTRODUCTION: Chronic musculoskeletal pain (CMP) is a very common symptom in patients with chronic kidney disease (CKD), and is associated with a significant deterioration in quality of life. AIMS: To determine the prevalence and clinical characteristics associated with CMP in patients with advanced CKD not on dialysis, and to analyse their relation with other uraemic symptoms and their prognosis significance. MATERIAL AND METHODS: Cross-sectional study to analyse the uraemic symptoms of an unselected cohort of patients with CKD stage 4-5 pre-dialysis. In order to characterise patients with CMP, demographic and anthropometric data were collected, as well as data on comorbidities and kidney function. In addition, inflammatory parameters, uric parameters, bone mineral metabolism including 25-hydroxycholecalciferol (25-OHCC), creatine kinase and drugs of potential interest including allopurinol, statins and erythropoiesis-stimulating agents were recorded. RESULTS: The study group consisted of 1169 patients (mean age 65±15 years, 54% male). A total of 38% of patients complained of CMP, and this symptom was more prevalent in women than in men (49 vs. 28%; P<.0001). Muscle weakness, pruritus, muscle cramps, ecchymosis, insomnia, oedema and dyspnoea were the most common symptoms associated with CMP. There were no significant associations between serum levels of creatine kinase, 25-OHCC, treatment with allopurinol, statins or erythropoiesis-stimulating agents and CMP. The female gender, elderly age, obesity, comorbidity (mainly diabetes, heart failure or COPD), and elevated levels of inflammatory markers (C-reactive protein and non-neutrophilic leukocytes) were the best determinants of CMP. While patients with CMP showed a worse survival rate, a multivariate analysis adjusted for demographic data ruled out the independent association of CMP with mortality. CONCLUSIONS: CMP is highly prevalent in patients with advanced CKD and is associated with other common symptoms of chronic uraemia. As with the general population, elderly age, the female gender, obesity and some comorbid conditions are the best determinants of CMP. Increased inflammatory markers commonly observed in patients with CMP may have a relevant role in its pathogenesis.

Evaluation of the Relative Performance of Drug-Induced Skeletal Muscle Injury Biomarkers in Rats.

Novel skeletal muscle (SKM) injury biomarkers that have recently been identified may outperform or add value to the conventional SKM injury biomarkers aspartate transaminase (AST) and creatine kinase (CK). The relative performance of these novel biomarkers of SKM injury including skeletal troponin I (sTnI), myosin light chain 3 (Myl3), CK M Isoform (Ckm), and fatty acid binding protein 3 (Fabp3) was assessed in 34 rat studies including both SKM toxicants and compounds with toxicities in tissues other than SKM. sTnI, Myl3, Ckm, and Fabp3 all outperformed CK or AST and/or added value for the diagnosis of drug-induced SKM injury (ie, myocyte degeneration/necrosis). In addition, when used in conjunction with CK and AST, sTnI, Myl3, CKm, and Fabp3 individually and collectively improved diagnostic sensitivity and specificity, as well as diagnostic certainty, for SKM injury and responded in a sensitive manner to low levels of SKM degeneration/necrosis in rats. These findings support the proposal that sTnI, Myl3, Ckm, and Fabp3 are suitable for voluntary use, in conjunction with CK and AST, in regulatory safety studies in rats to monitor drug-induced SKM injury and the potential translational use of these exploratory biomarkers in early clinical trials to ensure patient safety.

Prognostic prediction of troponins in cardiac myxoma: case study with literature review.

OBJECTIVE: It was supposed that troponins in cardiac myxoma patients might be in a same fashion as in the conditions without myocardial injury. In order to verify this hypothesis, troponins in cardiac myxoma patients were discussed by presenting a comprehensive retrieval of the literature with incorporating the information of a recent patient. METHODS: Postoperative detections of troponin I, creatine kinase isoenzyme MB (CK-MB) and N-terminal pro-B-type natriuretic peptide revealed elevated troponin I and CK-MB and normal N-terminal pro-B-type natriuretic peptide. Postoperative troponin I and CK-MB shared a same trend, reaching a peak value at postoperative hour 2, gradually decreased on postoperative day 1, and reached a plateau on postoperative days 7 and 13. A significant correlation could be noted between the postoperative values of the two indicators (Y = 0.0714X + 0.6425, r2 = 0.9111, r=0.9545, P=0.0116). No significant linear correlation between troponin I and N-terminal pro-B-type natriuretic peptide were found. Literature review of troponins in cardiac myxoma patients revealed the uncomplicated patients had a normal or only slightly elevated troponin before open heart surgery. However, the complicated patients (with cerebral or cardiac events) showed a normal preoperative troponin in 3 (23.1%) and an elevated troponin in 10 (76.9%) patients (χ2 = 7.54, P = 0.0169, Fisher's exact test). The overall quantitative result of troponin I was 2.45 ± 2.53 µg/L, and that of troponin T was 3.10 ± 4.29 mg/L, respectively. CONCLUSION: Troponins are not necessarily elevated in patients with a cardiac myxoma without coronary syndrome. By contrast, patients with a cardiac myxoma with an elevated troponin may herald the presence of an associated coronary event. An old cerebral infarct does not necessarily cause an elevation of troponin or B-type natriuretic peptide, or new neurological events, but might lead to a delayed awakening.

Growth hormone-releasing hormone agonists reduce myocardial infarct scar in swine with subacute ischemic cardiomyopathy.

BACKGROUND: Growth hormone-releasing hormone agonists (GHRH-As) stimulate cardiac repair following myocardial infarction (MI) in rats through the activation of the GHRH signaling pathway within the heart. We tested the hypothesis that the administration of GHRH-As prevents ventricular remodeling in a swine subacute MI model. METHODS AND RESULTS: Twelve female Yorkshire swine (25 to 30 kg) underwent transient occlusion of the left anterior descending coronary artery (MI). Two weeks post MI, swine were randomized to receive injections of either 30 µg/kg GHRH-A (MR-409) (GHRH-A group; n=6) or vehicle (placebo group; n=6). Cardiac magnetic resonance imaging and pressure-volume loops were obtained at multiple time points. Infarct, border, and remote (noninfarcted) zones were assessed for GHRH receptor by immunohistochemistry. Four weeks of GHRH-A treatment resulted in reduced scar mass (GHRH-A: -21.9 ± 6.42%; P=0.02; placebo: 10.9 ± 5.88%; P=0.25; 2-way ANOVA; P=0.003), and scar size (percentage of left ventricular mass) (GHRH-A: -38.38 ± 4.63; P=0.0002; placebo: -14.56 ± 6.92; P=0.16; 2-way ANOVA; P=0.02). This was accompanied by improved diastolic strain. Unlike in rats, this reduced infarct size in swine was not accompanied by improved cardiac function as measured by serial hemodynamic pressure-volume analysis. GHRH receptors were abundant in cardiac tissue, with a greater density in the border zone of the GHRH-A group compared with the placebo group. CONCLUSIONS: Daily subcutaneous administration of GHRH-A is feasible and safe in a large animal model of subacute ischemic cardiomyopathy. Furthermore, GHRH-A therapy significantly reduced infarct size and improved diastolic strain, suggesting a local activation of the GHRH pathway leading to the reparative process.