The Cardiac Troponin T and I are highly cardiac specific biochemical markers of myocardial injury. They are very sensitive markers to detect all kinds of myocardial injury, and are able to distinguish myocardial injury and skeletal injury. Furthermore, They are independent predictor of future cardiac events. Such markers are now widely used in the clinic practice. It is prospective to use them in Forensic Medical Science.
Biomarkers ; Forensic Medicine ; Humans ; Myocardial Infarction/blood* ; Myocardium/metabolism* ; Troponin I/blood* ; Troponin T/blood*

Child ; Child, Preschool ; Female ; Heart Defects, Congenital ; metabolism ; Humans ; Male ; Troponin I ; metabolism

The aim of the present study was to investigate the expressions of calpain and calpastatin in the myocardium of simulated weightlessness rats, and to elucidate the underlying mechanism of cardiac troponin I (cTnI) degradations. Tail-suspended (SUS) rats were used as a simulated weightlessness model on the ground. The myocardium of rats was homogenized, and the expressions of calpain-1, calpain-2, calpastatin and cTnI were analyzed by Western blotting technique. Calpastatin expression was significantly decreased in 2- and 4-week SUS groups compared with that in the synchronous controls (P<0.05). Calpain-2 expression was slightly decreased, whereas calpain-1 expression was unaltered in SUS groups. However, calpain-1/calpastatin and calpain-2/calpastatin ratios were increased after tail-suspension, being significantly higher in 2- and 4-week SUS groups than those in the synchronous controls (P<0.05, P<0.01). Cardiac TnI degradation was significantly increased after tail-suspension (P<0.01), but cTnI degradation in both SUS and control groups was significantly inhibited by a non-specific inhibitor of calpain, PD150606 (P<0.01). These results suggest that an increase in calpain activity may enhance cTnI degradation in the myocardium of tail-suspended rats.
Animals ; Calcium-Binding Proteins ; metabolism ; Calpain ; metabolism ; Hindlimb Suspension ; Myocardium ; metabolism ; Proteolysis ; Rats ; Troponin I ; metabolism ; Weightlessness Simulation

OBJECTIVETo establish a BALB/c mice model system of cytomegalovirus-induced myocarditis.

METHODSTwenty five specific pathogen-free inbred female BALB/c mice (5 weeks old, 16 - 18 g, seronegative for MCMV) were infected with 1 x 10(4) PFU MCMV by the intraperitoneal (i.p.) route. All experimental mice were sacrificed at 3, 5, 7, 10, 14 days i.p. (n = 5 per time point). Hearts were removed under aseptic conditions, and were transected along the midline. One part of each heart was processed with Bouin's fixative for histological examination. The other part of each heart was immediately frozen in liquid nitrogen and stored at -80 degrees C until MCMV titre was determined by plaque assay. Serum cTnI level was assayed by ELISA.

RESULTSMCMV was detected in the hearts at extremely low levels on 3 days i.p. and could not be detected on 10 days i.p. A mixed cellular infiltrate composed of polymorphonuclear neutrophils and mononuclear lymphocytes was observed on 3 days, which reached a peak at 7 to 10 days after MCMV infection and was maintained for at least 3 - 4 months postinfection. Serum cTnI levels were elevated on 3 days i.p., reaching a peak at 7 to 10 days i.p..

CONCLUSIONSThese data highlight the possible therapeutic uses of antiviral drugs in viral myocarditis as well as further elucidating the pathogenic nature of the disease.

Animals ; Disease Models, Animal ; Female ; Herpesviridae Infections ; pathology ; Mice ; Mice, Inbred BALB C ; Muromegalovirus ; Myocarditis ; virology ; Troponin I ; metabolism

OBJECTIVETo study possible correlation between matrix metalloproteinases (MMPs) activities and myocardial injury after asphyxia in neonatal Wistar rats.

METHODSixty neonatal Wistar rats (7 to 10 days old) were randomly divided into four groups: control group (group D); asphyxia groups A, B and C (1 day, 7 days, 14 days after asphyxia), every group had 15 rats. In the asphyxia groups, animal model was produced by normobaric asphyxia. Groups A, B and C were sacrificed on days 1, 7 and 14 days after asphyxia, and group D rats were sacrificed on the 7 th day. Then the heart blood was taken to tested the serum cTnI. The myocardial MMPs-3 and 9 activity was measured by using immunohistochemical assay. Histological sections of the hearts were stained with hematoxylin-eosin and myocardial histopathological scores were determined under an optical microscope. The amount of myocardial collagen was measured by means of chloramines T.

RESULTScTnI was significantly higher in group A (0.3680 +/- 0.40 ng/ml) than group D (0.0783 +/- 0.06 ng/ml) (P < 0.05), and was lower in group B (0.1889 +/- 0.15 ng/ml) but still significantly different from that of group D (P < 0.05), and declined to the normal level in group C (0.1338 +/- 0.07 ng/ml), but the difference between groups C and D was not significant (P > 0.05). Myocardial tissue MMPs-3 activity was transiently high in group A (0.1847 +/- 0.04), higher in group B (0.2780 +/- 0.05) as compared to group D (0.1213 +/- 0.03) (P < 0.05 for all). The activity of MMPs-3 increased earlier than that of MMPs-9. The amount of myocardial collagen of group B (38.94 +/- 0.67) and C (40.69 +/- 0.75) was significantly greater than that of group D (P < 0.05). Myoardial tissue MMPs-3 and MMPs-9 positively correlated with myocardial histopathological scores (r = 0.669, 0.667, P < 0.05) and myocardial collagen (r = 0.482, 0.679, P < 0.05).

CONCLUSIONSIn rats with asphyxia, there was an excess activation of myocardial MMPs-3 and MMPs-9 activities and secondary to which, the quantity of myocardial collagen increased. The injuries of myocardium may be closely associated with myocardial tissue MMPs. MMPs may be used to evaluate the severity of myocardial interstitial damage.

Animals ; Asphyxia ; metabolism ; pathology ; Collagen ; metabolism ; Disease Models, Animal ; Matrix Metalloproteinase 3 ; metabolism ; Matrix Metalloproteinase 9 ; metabolism ; Myocardium ; metabolism ; pathology ; Rats ; Rats, Wistar ; Troponin I ; blood

OBJECTIVETo investigate the changes in aquaporin-1 (AQP-1) expression in myocardium of scalded rats in early stage of a burn injury, and to analyze its relationship with myocardial edema.

METHODSThirty-six healthy Wistar rats were divided into normal control (n = 6, without scald) and scald (n = 30) groups according to the random number table. Rats in scald group were inflicted with 30%TBSA full-thickness scald on the back, and intraperitoneally injected with Ringer's solution for antishock treatment. Myocardium tissue from left ventricle and serum specimen in rats of scald group were collected at post scald hours (PSH) 2, 8, 12, 24, and 48 (with 6 rats at each time point). Myocardial water ratio was determined by dry-wet weight method. The distribution of AQP-1 protein in myocardium was observed with immunohistochemical staining. The expression of myocardial AQP-1 mRNA was assessed with quantitative real-time PCR. The serum content of cardiac troponin-I (cTnI) was determined with ELISA. The rats in normal control group were detected with above-mentioned method. Data were processed with one way analysis of variance and LSD test. Correlation analysis was performed between AQP-1 mRNA and myocardial water ratio, AQP-1 mRNA and the serum content of cTnI in scald group at each time point.

RESULTSCompared with that in normal control group, the myocardial water ratio in scald group was markedly increased during PSH 8-48 (P values all below 0.01), and it peaked at PSH 12 [(80.79 ± 0.12)%]. In both groups, AQP-1 was mainly expressed in endothelial cells of capillaries and pericellular membrane of myocardial cells. The expression of AQP-1 in scald group was markedly increased from PSH 2 to PSH 48. The expression of myocardial AQP-1 mRNA in scald group was markedly higher from PSH 2 to PSH 48 than that in normal control group (P values all below 0.01), and it peaked at PSH 12 [(6.2 ± 0.7)%]. The serum content of cTnI in scald group was obviously higher from PSH 2 to PSH 48 than that in normal control group (P values all below 0.01), and it peaked at PSH 12 [(5.83 ± 0.51) µg/L]. There were statistically positive correlations between AQP-1 mRNA expression and myocardial water ratio (r = 0.849, P < 0.01), AQP-1 mRNA expression and the serum content of cTnI (r = 0.973, P < 0.01) in scald group.

CONCLUSIONSAQP-1 may play a key role in the development of myocardial edema in rats with scald.

Animals ; Aquaporin 1 ; metabolism ; Burns ; metabolism ; pathology ; Cardiomyopathies ; metabolism ; Disease Models, Animal ; Edema ; metabolism ; Myocardium ; metabolism ; pathology ; Rats ; Rats, Wistar ; Troponin I ; blood

BACKGROUNDPrevious studies have suggested that hypothyroidism correlated with coronary heart diseases (CHD) mortality in long-term cohort, but whether the thyroid function status is associated with myocardial injury in acute ST-elevation myocardial infarction (STEMI) has not been investigated sufficiently.

METHODSFive hundred and eighty-two hospitalized patients from January 2010 to December 2011, with the diagnosis of STEMI, were enrolled in this study. All patients underwent testing for thyroid function status, cardiac troponin I (cTnI), cardiac enzymes, C-reactive protein (CRP). We investigated the association between thyroid hormone levels and cardiac markers (creatine kinase-MB and cTnI), and thus evaluated the potential role of thyroid function status in predicting the myocardial injury.

RESULTSThere were 76 patients (13.06%) who had hypothyroidism including low-T3-syndrome (34 patients, 5.84%), subclinical hypothyroidism (28 patients, 4.81%) and clinical hypothyroidism (14 patients, 2.41%). After adjusting for conventional risk factors (age, gender, smoking, diabetes mellitus, dyslipidemia, hypertension), free triiodothyronine (FT3) was significantly and negatively correlated with log-CKMB (r = -0.244, P < 0.001) and log-cTnI (r = -0.290, P < 0.001), indicating that the lower thyroid hormone level correlates with the severer cardiac injury in STEMI patients. FT3 also had a moderate negative correlation with CRP (r = -0.475, P < 0.001), which might indicate that hypothyroidism may activate the inflammation response. No significant correlation was found between other thyroid parameters (TSH, FT4) and cardiac markers.

CONCLUSIONSAs the lower FT3 level correlates with higher level of cardiac markers and lower left ventricular ejection fraction (LVEF), the hypothyroidism may be a predictor for myocardial injury in STEMI. And these results may warrant further study to investigate whether reversing the hypothyroidism could benefit the STEMI patients.

Aged ; C-Reactive Protein ; metabolism ; Echocardiography ; Female ; Humans ; Male ; Middle Aged ; Myocardial Infarction ; blood ; Myocardium ; metabolism ; pathology ; Thyroid Gland ; metabolism ; Triiodothyronine ; blood ; Troponin I ; metabolism

The troponin I subunit (TnI) was used as a molecular marker to explore the relationship between the resting intracellular Ca(2+) concentration and myofibril degradation in muscle fibers. The isolated soleus muscle strips of rats were treated by caffeine and H2O2. Caffeine is an opener to increase the calcium release channel open probability of sarcoplasmic reticulum (SR) in contraction phase. H2O2 induces a calcium leak of SR calcium release channel in relaxation phase. The expression and degradation of TnI were detected by Western blot. The resting tension of tetanic contraction and expression of TnI were not changed, but the developed tension was lowered in isolated soleus muscle strips during 40 min of calcium-free Krebs perfusion. Low concentrations of caffeine (1 and 5 mmol/L) perfusion induced a transient increase in resting tension during fatigue period, but did not alter the extent of fatigue, recovery rate after fatigue and expression of TnI in muscle strips. High concentration of caffeine (10 mmol/L) perfusion induced a progressive increase in resting tension, a higher rate of fatigue and a decrease in recovery rate after fatigue in muscle strips. There was a detectable degradation of TnI in soleus after 10 mmol/L caffeine treatment. H2O2 perfusion facilitated a progressive increase in resting tension in a dose-dependent manner, but did not influence the fatigue rate of tetanic contraction. The recovery rate after fatigue showed a quick resumption before decline during H2O2 perfusion. Degradation of TnI occurred in 5 and 10 mmol/L H2O2-treated soleus muscles. Since resting tension is dependent on intracellular Ca(2+) concentration, the above-mentioned results suggest that SR Ca(2+) leakage in relaxation phase may induce a degradation of TnI in skeletal muscle fibers.
Animals ; Caffeine ; pharmacology ; Calcium ; metabolism ; Calcium Channels ; metabolism ; Hydrogen Peroxide ; pharmacology ; In Vitro Techniques ; Muscle Fibers, Skeletal ; metabolism ; Rats ; Sarcoplasmic Reticulum ; pathology ; Troponin I ; metabolism

OBJECTIVETo investigate the association between cTnI phosphorylation/degradation and cardiomyopathies in extransplanted myocardium.

METHODScTnI phosphorylation and degradation as well as PKC (beta1, beta2) expressions were determined in extransplanted hearts from patients with cardiomyopathies (n = 8) and from traffic accidents (n = 6) by Western blot.

RESULTSThe cTnI bands were observed in LV myocardium of cardiomyopathy patients and normal myocardium while and cTnI degradation bands were only detected in LV myocardium from patients with cardiomyopathies. The phosphorylated cTnI bands were significantly upregulated in LV myocardium of cardiomyopathy patients compared to normal myocardium (P < 0.05). There was no myocardial PKCbeta1, PKCbeta2 expression in all examined hearts.

CONCLUSIONThe cTnI degradation products and increased phosphorylated cTnI expression are likely involved in the pathogenesis and development of cardiomyopathy.

Adult ; Cardiomyopathies ; metabolism ; pathology ; Female ; Humans ; Male ; Middle Aged ; Myocardium ; metabolism ; pathology ; Phosphorylation ; Protein Kinase C ; metabolism ; Protein Kinase C beta ; Signal Transduction ; Troponin I ; metabolism

OBJECTIVETo investigate the expression of representative heart-specific primary microRNAs (pri-miRNAs) in the cardiomyocyte-like cells differentiated from human mesenchymal stem cells (hMSCs).

METHODSThe phenotype of hMSCs isolated was identified by flow cytometry using monoclonal antibodies against FITC-conjugated CD29, CD34, and CD11b. The third-passage hMSCs were induced to differentiate into cardiomyocyte-like cells by 5-azacytidine and indirect coculture with neonatal rat myocytes, respectively. Immunocytochemical analysis was performed to detect the expression of the cardiac-specific proteins, namely cardiac troponin I (cTnI) and sarcomeric alpha-actinin, in the cardiomyocyte-like cells differentiated from hMSCs. RT-PCR and DNA sequencing were used to identify the expression of the 5 representative heart-specific pri-miRNAs.

RESULTSHigh hMSC marker CD29 expression rate (98.87%) and low hematopoietic cell markers CD34 (5%) and CD11b (0.4%) expression rates were identified in the hMSCs isolated. cTnI and sarcomeric alpha-actinin expression occurred in the hMSCs following induction with the 2 differentiation-inducing methods. miRNA-143 and -181 expressions were induced in the hMSCs by 5-azacytidine and miRNA-143, -181, -206, and -208 expressions were induced by indirect coculture with neonatal rat myocytes, but pri-miRNA-1-2 expression failed to be induced by these two induction methods.

CONCLUSIONExpressions of the representative heart-specific pri-miRNAs in different patterns can be induced in cardiomyocyte-like cells differentiated from hMSCs by 5-azacytidine and indirect coculture with neonatal rat myocytes.

Actinin ; metabolism ; Animals ; Cell Differentiation ; Coculture Techniques ; Humans ; Mesenchymal Stromal Cells ; cytology ; MicroRNAs ; metabolism ; Myocytes, Cardiac ; cytology ; metabolism ; Rats ; Troponin I ; metabolism