The fact that different types of cardiomyopathies can be manifested by the same sarcomere protein gene mutation in a single family is well known. However, mixed features of different types of cardiomyopathies in a single patient have not been well appreciated. We identified a novel mutation in cardiac troponin I3 (Arg186Gly) in the present case, and two of the family members showed mixed morphologic features of hypertrophic cardiomyopathy and left ventricular non-compaction. Moreover, both the features of cardiomyopathies were not apparent for each type of cardiomyopathy. In the patient's family, four other members had unexpected deaths before the age of 30.
Cardiomyopathies* ; Cardiomyopathy, Hypertrophic ; Cardiomyopathy, Restrictive ; Humans ; Sarcomeres ; Troponin*

Fusion loss or anomaly of eye muscle and its nerve is a cause of strabismus. This induces adaptation of vergence and muscle length, the mechanisms of which are normally responsible for long-term maintenance of ocular alignment and orthophorization. To determine variability of muscle length adaptation according to age, we divided white rabbits into three groups: Group I(less than 8 weeks of age and 15000gm of body weight), Group II(10~14 weeks and 1500~2000gm), GroupIII(more than 16 weeks and 2500gm). Under local anesthesia with intravenous pentobarbital sodium, the right eyeball was fixed in exotropic position by suturing through the periosteum of the lateral canthal region with 5-o polypropylene. The muscles of left eye were not operated and served as a control. We examined electron microscopically the changes in sarcomere of the experimental right medial rectus(RMR) and right lateral rectus(RLR) after sacrificing four rabbits of each group at 1, 2 and 4 weeks, respectively. Regardless of age, when the muscle(RLR) was immobilized in the lengthened position, sarcomeres were added on and its length decreased, and when the muscle(RMR) was immobilized in the shortened position, sarcomeres were lost and its length increased. In conclusion, the study revealed that experimental extraocular muscle of rabbit is adapted in the direction to produce maximal power of its muscle and maintain ocular alignment constantly.
Anesthesia, Local ; Exotropia* ; Muscles ; Pentobarbital ; Periosteum ; Polypropylenes ; Rabbits ; Sarcomeres ; Strabismus

Objective: To analyze the clinical and genetic characteristics of clinical subtypes of non-obstructive hypertrophic cardiomyopathy (HCM). Methods: It was a cohort study. Patients with non-obstructive HCM admitted to Fuwai Hospital, Chinese Academy of Medical Sciences, from January 1999 to April 2019 were enrolled. According to the characteristics of cardiac morphology and function shown by echocardiography, the patients were divided into common type, dilated type, restricted type and reduced ejection fraction type. The clinical data of the patients were recorded, and 8 sarcomere pathogenic genes were screened by full exon sequencing or panel sequencing. Patienst were followed up and cardiovascular endpoint events were recorded. Results: A total of 815 patients with non-obstructive HCM were enrolled, including 27 (3.3%) restricted type, 51 (6.3%) dilated type, 30 (3.7%) reduced ejection fraction type and 707 (86.7%) common type. A total of 704 out of 815 patients underwent genetic testing. Among them, 299 (42.5%) patients carried at least 1 sarcomere gene mutation. MYBPC3 and MYH7 mutation accounted for 42.1% (126/299) and 35.8% (107/299) respectively. 66.7% (16/24) of the patients with restricted type carried sarcomere gene mutation, which was higher than that in patients with dilated type (36.4% (16/44)) and in common type (41.5% (250/602), P=0.015). Among the patients with reduced ejection fraction, 56.7% (17/30) patients carried sarcomere gene mutations, 23.3% (7/30) carried multiple sarcomere mutations, which was higher than that in restricted type (8.3% (2/24)), in dilated type (9.1% (4/44)) and in common type 4.2% ((24/577), P<0.001). MYH7 and MYBPC3 were the main mutation gene types of all clinical subtypes, and the genotypes were similar among groups (all P>0.05). Seven hundred and three out 815 patients were followed up for 2.9 (1.4, 4.0) years. There were 53(7.5%) cardiovascular death. Cardiovascular death occurred in 5.0% (29/578) patients with common type, 13.0% (3/23) patients with restricted type, 16.3% (7/43) patients with dilated type and 46.7% (14/30) patients with decreased ejection fraction. Univariate Cox proportional hazards model analysis showed that the risk of cardiovascular death in patients with restricted, dilated and reduced ejection fraction type was higher than that in patients with common type (P<0.001). After adjusting for gender, age of onset, body mass index, history of hypertension, coronary heart disease and diabetes, multivariate Cox proportional hazards model analysis showed that the HR of cardiovascular death in patients with restricted, dilated and reduced ejection fraction type were 5.454 (95%CI 1.137-26.157, P=0.034) and 6.597 (95%CI 1.632-26.667, P=0.008) and 9.028 (95%CI 2.201-37.039, P=0.002) respectively, as compared to patients with common type. Conclusions: Most of the patients with non-obstructive HCM are common type, featured by mild clinical manifestations and good prognosis. Although the proportion of restricted type and dilated type is relatively low, and cardiac systolic function is mostly preserved, the clinical phenotype and prognosis of these patients are similarly severe and poor as patients with reduced ejection fraction. The genotypes are similar in different clinical subtypes, but the proportion of patients with sarcomere gene mutation is higher in restricted type, and the proportion of patients with multiple sarcomere gene mutation is higher in decreased ejection fraction type.
Cardiomyopathy, Hypertrophic/genetics* ; Cohort Studies ; Humans ; Mutation ; Phenotype ; Sarcomeres/genetics*

Hypertrophic cardiomyopathy (HCM) is caused by dominant mutations in sarcomere genes. The diagnosis of HCM is usually established by identifying unexplained left ventricular hypertrophy (LVH) on cardiac imaging studies; however, LVH is not an invariable feature of disease. The expression of LVH is highly age-dependent, and LV wall thickness is frequently normal during childhood. Overt development of hypertrophy, and the ability to make a clinical diagnosis, does not typically occur until adolescence or later. Genetic testing allows identification of family members who have inherited the pathogenic sarcomere mutation (G +) before the emergence of clinical manifestations (LVH -). As such, a new and important subset of individuals with preclinical HCM (G+ / LVH-) can be identified early in life, before a clinical diagnosis can be made. Our evaluation of preclinical HCM has indicated that although there are no distinguishing morphologic features of early disease, there is evidence of myocardial dysfunction prior to the development of LVH. Subtle impairment of diastolic function is detectable in otherwise healthy sarcomere mutation carriers and can differentiate these family members from those who did not inherit the mutation. In contrast, systolic function appears relatively preserved in preclinical HCM, but impaired in overt disease. This preliminary finding suggests that both the sarcomere mutation and the characteristic changes in myocardial architecture (LVH, fibrosis and disarray) are required to perturb force generation. By studying this intriguing preclinical cohort, we can better understand the early stages of disease pathogenesis and potentially develop therapy to alter the clinical expression of sarcomere mutations.
Cardiomyopathy, Hypertrophic ; diagnosis ; genetics ; Genotype ; Humans ; Mutation ; Pedigree ; Phenotype ; Sarcomeres ; genetics

BACKGROUND/AIMS: External anal sphincter (EAS) and puborectalis muscle (PRM) play important role in anal continence function. Based on length-tension measurement, we recently reported that the human EAS muscle operates at short sarcomere length under physiological conditions. Goal of our study was to determine if PRM also operates at the short sarcomere length. METHODS: Length-tension relationship of the PRM muscle was studied in vivo in 10 healthy nullipara women. Length was altered by vaginal distension using custom-designed probes of 5, 10, 15, 20, 25 and 30 mm diameters as well as by distending a polyethylene bag with different volumes of water. Probes were equipped with a reverse perfuse sleeve sensor to measure vaginal pressure (surrogate of PRM tension). PRM electromyogram (EMG) was recorded using wire electrodes. Three-dimensional ultra-sound images were obtained to determine effect of vaginal distension on PRM length. RESULTS: Ultrasound images demonstrate distension volume dependent increase in PRM length. Rest and squeeze pressures of vaginal bag increased with the increase in bag volume. Similarly, the change in vaginal pressure, which represents the PRM contraction increased with the increase in the probe size. Increase in probe size was not associated with an increase in EMG activity (a marker of neural drive) of the PRM. CONCLUSIONS: Probe size dependent increase in PRM contraction pressure, in the presence of constant EMG (neural input) proves that the human PRM operates at short sarcomere length. Surgically adjusting the PRM length may represent a novel strategy to improve treat anal continence and possibly other pelvic floor disorders.
Anal Canal ; Electrodes ; Fecal Incontinence* ; Female ; Humans ; Muscles ; Pelvic Floor Disorders* ; Polyethylene ; Sarcomeres ; Ultrasonography ; Water

OBJECTIVETo investigate the histopathological features of primary restrictive cardiomyopathy (PRCM).

METHODSNine extransplanted hearts from heart transplantation recipients were examined. Gross and histopathological findings were observed, photographed and final pathological diagnosis was compared to clinical diagnosis. The myocardial ultrastructure changes were determined using transmission electron microscopy.

RESULTSThe hallmark pathologic feature of PRCM was distinguished by myocardial cell degeneration and hyperplastic collagen fibrils around the myocardial cells.Fibrosis was severer in left ventricle free wall than in ventricular septum and right ventricle. The degree of myocardial cell degeneration and poloidal disorder were severer in patients with reduced ejection fraction (EF) than in patients with preserved EF. Transmission electron microscope evidenced severe interstitial fibrosis, myofibrillar changes of sarcomere structure, abnormalities both on intercalated disc number and distribution.

CONCLUSIONSPRCM is characterized by hyperplastic collagen fibrils around the cardiomyocytes. Fibrosis is severer in left ventricle than in right ventricle. Sarcomere dysplasia is the main cause of PRCM, and ultrastructural examination is helpful for PRCM diagnosis.

Cardiomyopathy, Restrictive ; surgery ; Fibrosis ; Heart Transplantation ; Heart Ventricles ; Humans ; Myocardium ; pathology ; Myocytes, Cardiac ; Sarcomeres

Objective: To observe the association between clinical phenotypes of hypertrophic cardiomyopathy (HCM) patients and a rare calcium channel and regulatory gene variation (Ca²⁺ gene variation) and to compare clinical phenotypes of HCM patients with Ca²⁺ gene variation, a single sarcomere gene variation and without gene variation and to explore the influence of rare Ca²⁺ gene variation on the clinical phenotypes of HCM. Methods: Eight hundred forty-two non-related adult HCM patients diagnosed for the first time in Xijing Hospital from 2013 to 2019 were enrolled in this study. All patients underwent exon analyses of 96 hereditary cardiac disease-related genes. Patients with diabetes mellitus, coronary artery disease, post alcohol septal ablation or septal myectomy, and patients who carried sarcomere gene variation of uncertain significance or carried>1 sarcomere gene variation or carried>1 Ca²⁺ gene variation, with HCM pseudophenotype or carrier of ion channel gene variations other than Ca²⁺ based on the genetic test results were excluded. Patients were divided into gene negative group (no sarcomere or Ca²⁺ gene variants), sarcomere gene variation group (only 1 sarcomere gene variant) and Ca²⁺ gene variant group (only 1 Ca²⁺ gene variant). Baseline data, echocardiography and electrocardiogram data were collected for analysis. Results: A total of 346 patients were enrolled, including 170 patients without gene variation (gene negative group), 154 patients with a single sarcomere gene variation (sarcomere gene variation group) and 22 patients with a single rare Ca²⁺ gene variation (Ca²⁺ gene variation group). Compared with gene negative group, patients in Ca²⁺ gene variation group had higher blood pressure and higher percentage of family history of HCM and sudden cardiac death (P<0.05); echocardiographic results showed that patients in Ca²⁺ gene variation group had thicker ventricular septum ((23.5±5.8) mm vs. (22.3±5.7) mm, P<0.05); electrocardiographic results showed that patients in Ca²⁺ gene variation group had prolonged QT interval ((416.6±23.1) ms vs. (400.6±47.2) ms, P<0.05) and higher RV5+SV1 ((4.51±2.26) mv vs. (3.50±1.65) mv, P<0.05). Compared with sarcomere gene variation group, patients in Ca²⁺ gene variation group had later onset age and higher blood pressure (P<0.05); echocardiographic results showed that there was no significant difference in ventricular septal thickness between two groups; patients in Ca²⁺ gene variation group had lower percentage of left ventricular outflow tract pressure gradient>30 mmHg (1 mmHg=0.133 kPa, 22.8% vs. 48.1%, P<0.05) and the lower early diastolic peak velocity of the mitral valve inflow/early diastolic peak velocity of the mitral valve annulus (E/e') ratio ((13.0±2.5) vs. (15.9±4.2), P<0.05); patients in Ca²⁺ gene variation group had prolonged QT interval ((416.6±23.1) ms vs. (399.0±43.0) ms, P<0.05) and lower percentage of ST segment depression (9.1% vs. 40.3%, P<0.05). Conclusion: Compared with gene negative group, the clinical phenotype of HCM is more severe in patients with rare Ca²⁺ gene variation; compared with patients with sarcomere gene variation, the clinical phenotype of HCM is milder in patients with rare Ca²⁺ gene variation.
Humans ; Cardiac Surgical Procedures/methods* ; Cardiomyopathy, Hypertrophic/genetics* ; Echocardiography ; Electrocardiography ; Phenotype ; Sarcomeres/genetics* ; Adult

Titin, the largest known protein in the body expressed in three isoforms (N2A, N2BA and N2B), is essential for muscle structure, force generation, conduction and regulation. Since the 1950s, muscle contraction mechanisms have been explained by the sliding filament theory involving thin and thick muscle filaments, while the contribution of cytoskeleton in force generation and conduction was ignored. With the discovery of insoluble protein residues and large molecular weight proteins in muscle fibers, the third myofilament, titin, has been identified and attracted a lot of interests. The development of single molecule mechanics and gene sequencing technology further contributed to the extensive studies on the arrangement, structure, elastic properties and components of titin in sarcomere. Therefore, this paper reviews the structure, isforms classification, elastic function and regulatory factors of titin, to provide better understanding of titin.
Connectin/genetics* ; Muscle Proteins/metabolism* ; Protein Isoforms/genetics* ; Sarcomeres/metabolism* ; Muscle Fibers, Skeletal/metabolism*

OBJECTIVE: To observe changes of the length of sarcomere of rat when restiffening. METHODS: We measured the length of sarcomere of quadriceps in 40 rats in different condition by scanning electron microscope. RESULTS: The length of sarcomere of rigor mortis without destroy is obviously shorter than that of restiffening. CONCLUSION The length of sarcomere is negatively correlative to the intensity of rigor mortis. Measuring the length of sarcomere can determine the intensity of rigor mortis and provide evidence for estimation of time since death.
Animals ; Female ; Male ; Microscopy, Electron ; Postmortem Changes ; Rats ; Rats, Wistar ; Rigor Mortis/pathology* ; Sarcomeres/ultrastructure* ; Time Factors

The effects of unilateral sciatic neurectomy on gastrocnemius muscle were studied in adult male rats. The morphological changes of both gastrocnemius muscles were observed by light and electron microscopy. Western blot analysis was performed to study the protein expression. Following the denervation, the affected muscle weights decreased significantly than normal. And the denervation led to a significant reduction in the area and diameter of muscle fibers on light microscopy. The affected muscle fibers showed the decreasing in size and the irregularity of myofibrilar arrangement on electron microscopy. On transverse view, the area of affected muscle fibers were smaller than normal. Their myofibrils were smaller and very irregular in size. The thin and thick myofilaments were not regular and partially lost. Mitochondria between myofibrils and subsarcolemmal area in affected muscle fibers were damaged and partially lost. The sacoplasmic reticulum and T-tubules were mostly lost and irregular. Some satellite cells were observed adjacent the muscle fiber, but they were inactive morphologically. On longitudinal view, most of myofibrils in affected muscle fibers were lost generally or partially although the their most sarcomeres were regularly arranged. Z line and myofilaments were lost partially and were partially irregularly arranged. The loss of thin myofilaments was more than that of thick myofilaments. Much debris of cell organelles were scattered among myofibrils. The expression of MyoD and myogenin were decrease significantly and the expression of p-mTOR and p-FOXO1 were decreased, too. On the other hand, MuRF1 was increased significantly. Taken together, the main effect of gastrocnemius muscle by sciatic neurectomy is the atrophy as a result of the loss of myofilaments and cell organelles through the decrease of protein synthesis and the increase of protein degradation.
Adult ; Animals ; Atrophy ; Blotting, Western ; Denervation ; Hand ; Humans ; Light ; Male ; Microscopy ; Microscopy, Electron ; Mitochondria ; Muscle, Skeletal ; Muscles ; Myofibrils ; Myogenin ; Organelles ; Proteolysis ; Rats ; Reticulum ; Sarcomeres ; Sciatic Nerve ; Weights and Measures