Cardiac myosin super relaxation (SRX): a perspective on fundamental biology, human disease and therapeutics.

The fundamental basis of muscle contraction 'the sliding filament model' (Huxley and Niedergerke, 1954; Huxley and Hanson, 1954) and the 'swinging, tilting crossbridge-sliding filament mechanism' (Huxley, 1969; Huxley and Brown, 1967) nucleated a field of research that has unearthed the complex and fascinating role of myosin structure in the regulation of contraction. A recently discovered energy conserving state of myosin termed the super relaxed state (SRX) has been observed in filamentous myosins and is central to modulating force production and energy use within the sarcomere. Modulation of myosin function through SRX is a rapidly developing theme in therapeutic development for both cardiovascular disease and infectious disease. Some 70 years after the first discoveries concerning muscular function, modulation of myosin SRX may bring the first myosin targeted small molecule to the clinic, for treating hypertrophic cardiomyopathy (Olivotto et al., 2020). An often monogenic disease HCM afflicts 1 in 500 individuals, and can cause heart failure and sudden cardiac death. Even as we near therapeutic translation, there remain many questions about the governance of muscle function in human health and disease. With this review, we provide a broad overview of contemporary understanding of myosin SRX, and explore the complexities of targeting this myosin state in human disease.This article has an associated Future Leaders to Watch interview with the authors of the paper.

Human-induced pluripotent stem cells for modelling metabolic perturbations and impaired bioenergetics underlying cardiomyopathies.

Normal cardiac contractile and relaxation functions are critically dependent on a continuous energy supply. Accordingly, metabolic perturbations and impaired mitochondrial bioenergetics with subsequent disruption of ATP production underpin a wide variety of cardiac diseases, including diabetic cardiomyopathy, dilated cardiomyopathy, hypertrophic cardiomyopathy, anthracycline cardiomyopathy, peripartum cardiomyopathy, and mitochondrial cardiomyopathies. Crucially, there are no specific treatments for preventing the onset or progression of these cardiomyopathies to heart failure, one of the leading causes of death and disability worldwide. Therefore, new treatments are needed to target the metabolic disturbances and impaired mitochondrial bioenergetics underlying these cardiomyopathies in order to improve health outcomes in these patients. However, investigation of the underlying mechanisms and the identification of novel therapeutic targets have been hampered by the lack of appropriate animal disease models. Furthermore, interspecies variation precludes the use of animal models for studying certain disorders, whereas patient-derived primary cell lines have limited lifespan and availability. Fortunately, the discovery of human-induced pluripotent stem cells has provided a promising tool for modelling cardiomyopathies via human heart tissue in a dish. In this review article, we highlight the use of patient-derived iPSCs for studying the pathogenesis underlying cardiomyopathies associated with metabolic perturbations and impaired mitochondrial bioenergetics, as the ability of iPSCs for self-renewal and differentiation makes them an ideal platform for investigating disease pathogenesis in a controlled in vitro environment. Continuing progress will help elucidate novel mechanistic pathways, and discover novel therapies for preventing the onset and progression of heart failure, thereby advancing a new era of personalized therapeutics for improving health outcomes in patients with cardiomyopathy.

Mutation location of HCM-causing troponin T mutations defines the degree of myofilament dysfunction in human cardiomyocytes.

BACKGROUND: The clinical outcome of hypertrophic cardiomyopathy patients is not only determined by the disease-causing mutation but influenced by a variety of disease modifiers. Here, we defined the role of the mutation location and the mutant protein dose of the troponin T mutations I79N, R94C and R278C. METHODS AND RESULTS: We determined myofilament function after troponin exchange in permeabilized single human cardiomyocytes as well as in cardiac patient samples harboring the R278C mutation. Notably, we found that a small dose of mutant protein is sufficient for the maximal effect on myofilament Ca2+-sensitivity for the I79N and R94C mutation while the mutation location determines the magnitude of this effect. While incorporation of I79N and R94C increased myofilament Ca2+-sensitivity, incorporation of R278C increased Ca2+-sensitivity at low and intermediate dose, while it decreased Ca2+-sensitivity at high dose. All three cTnT mutants showed reduced thin filament binding affinity, which coincided with a relatively low maximal exchange (50.5 ± 5.2%) of mutant troponin complex in cardiomyocytes. In accordance, 32.2 ± 4.0% mutant R278C was found in two patient samples which showed 50.0 ± 3.7% mutant mRNA. In accordance with studies that showed clinical variability in patients with the exact same mutation, we observed variability on the functional single cell level in patients with the R278C mutation. These differences in myofilament properties could not be explained by differences in the amount of mutant protein. CONCLUSIONS: Using troponin exchange in single human cardiomyocytes, we show that TNNT2 mutation-induced changes in myofilament Ca2+-sensitivity depend on mutation location, while all mutants show reduced thin filament binding affinity. The specific mutation-effect observed for R278C could not be translated to myofilament function of cardiomyocytes from patients, and is most likely explained by other (post)-translational troponin modifications. Overall, our studies illustrate that mutation location underlies variability in myofilament Ca2+-sensitivity, while only the R278C mutation shows a highly dose-dependent effect on myofilament function.

Mapping signalling perturbations in myocardial fibrosis via the integrative phosphoproteomic profiling of tissue from diverse sources.

Study of the molecular basis of myocardial fibrosis is hampered by limited access to tissues from human patients and by confounding variables associated with sample accessibility, collection, processing and storage. Here, we report an integrative strategy based on mass spectrometry for the phosphoproteomic profiling of normal and fibrotic cardiac tissue obtained from surgical explants from patients with hypertrophic cardiomyopathy, from a transaortic-constriction mouse model of cardiac hypertrophy and fibrosis, and from a heart-on-a-chip model of cardiac fibrosis. We used the integrative approach to map the relative abundance of thousands of proteins, phosphoproteins and phosphorylation sites specific to each tissue source, to identify key signalling pathways driving fibrosis and to screen for anti-fibrotic compounds targeting glycogen synthase kinase 3, which has a consistent role as a key mediator of fibrosis in all three types of tissue specimen. The integrative disease-modelling strategy may reveal new insights into mechanisms of cardiac disease and serve as a test bed for drug screening.

Extracellular Volume Associates With Outcomes More Strongly Than Native or Post-Contrast Myocardial T1.

OBJECTIVES: Because risk stratification data represents a key domain of biomarker validation, we compared associations between outcomes and various cardiovascular magnetic resonance (CMR) metrics quantifying myocardial fibrosis (MF) in noninfarcted myocardium: extracellular volume fraction (ECV), native T1, post-contrast T1, and partition coefficient. BACKGROUND: MF associates with vulnerability to adverse events (e.g., mortality and hospitalization for heart failure [HHF]), but investigators still debate its optimal measurement; most histological validation data show strongest ECV correlations with MF. METHODS: We enrolled 1,714 consecutive patients without amyloidosis or hypertrophic cardiomyopathy from a single CMR referral center serving an integrated healthcare network. We measured T1 (MOdified Look-Locker Inversion recovery [MOLLI]) in nonenhanced myocardium, averaged from 2 short-axis slices (basal and mid) before and 15 to 20 min after a gadolinium contrast bolus. We compared chi-square test values from CMR MF measures in univariable and multivariable Cox regression models. We assessed "dose-response" relationships in Kaplan-Meier curves using log-rank statistics for quartile strata. We also computed net reclassification improvement (NRI) and integrated discrimination improvement (IDI for Cox models with ECV vs. native T1). RESULTS: Over a median of 5.6 years, 374 events occurred after CMR (162 HHF events and 279 deaths, 67 with both). ECV yielded the best separation of Kaplan-Meier curves and the highest log-rank statistics. In univariable and multivariable models, ECV associated most strongly with outcomes, demonstrating the highest chi-square test values. Native T1 or post-contrast T1 did not associate with outcomes in the multivariable model. ECV provided added prognostic value to models with native T1, for example, in multivariable models IDI = 0.0037 (95% confidence interval [CI]: 0.0009 to 0.0071), p = 0.02; NRI = 0.151 (95% CI: 0.022 to 0.292), p = 0.04. CONCLUSIONS: Analogous to histological previously published validation data, ECV myocardial fibrosis measures exhibited more robust associations with outcomes than other surrogate CMR MF measures. Superior risk stratification by ECV supports claims that ECV optimally measures MF in noninfarcted myocardium.

Low doses of BPA induced abnormal mitochondrial fission and hypertrophy in human embryonic stem cell-derived cardiomyocytes via the calcineurin-DRP1 signaling pathway: A comparison between XX and XY cardiomyocytes.

Humans are inevitably exposed to bisphenol A (BPA) via multiple exposure ways. Thus, attention should be raised to the possible adverse effects related to low doses of BPA. Epidemiological studies have outlined BPA exposure and the increased risk of cardiovascular diseases (such as cardiac hypertrophy), which has been confirmed to be sex-specific in rodent animals and present in few in vitro studies, although the molecular mechanism is still unclear. However, whether BPA at low doses equivalent to human internal exposure level could induce cardiac hypertrophy via the calcineurin-DRP1 signaling pathway by disrupting calcium homeostasis is unknown. To address this, human embryonic stem cell (H1, XY karyotype and H9, XX karyotype)-derived cardiomyocytes (CM) were purified and applied to study the low-dose effects of BPA on cardiomyocyte hypertrophy. In our study, when H1- and H9-CM were exposed to noncytotoxic BPA (8 ng/ml), markedly elevated hypertrophic-related mRNA expression levels (such as NPPA and NPPB), enhanced cellular area and reduced ATP supplementation, demonstrated the hypertrophic cardiomyocyte phenotype in vitro. The excessive fission produced by BPA was promoted by CnAß-mediated dephosphorylation of DRP1. At the molecular level, the increase in cytosolic Ca2+ levels by low doses of BPA could discriminate between H1- and H9-CM, which may suggest a potential sex-specific hypertrophic risk in cardiomyocytes in terms of abnormal mitochondrial fission and ATP production by impairing CnAß-DRP1 signaling. In CnAß-knockdown cardiomyocytes, these changes were highly presented in XX-karyotyped cells, rather than in XY-karyotyped cells.

Astragaloside IV inhibits cardiac fibrosis via miR-135a-TRPM7-TGF-ß/Smads pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Cardiac fibrosis is a common characteristic of many cardiac diseases. Our previous results showed that TRPM7 channel played an important role in the fibrosis process. MicroRNA-135a was reported to get involved in the fibrotic process. Astragalus membranaceus (Fisch.) Bunge was widely used in Chinese traditional medicine and showed cardiac protective effects in previous researches. Astragaloside IV(ASG), which is regarded as the most important ingredient of Astragalus, has been showed the effect of cardiac protection via various mechanisms, while no data suggested its action related to miRNAs regulation. AIM OF THE STUDY: The objective of this article is to investigate the inhibition effect of ASG on cardiac fibrosis through the miR-135a-TRPM7-TGF-ß/Smads pathway. MATERIALS AND METHODS: We extracted the active components from herb according to the paper and measured the content of ASG from the mixture via HPLC. The inhibition potency of cardiac hypertrophy between total extract of Astragalus and ASG was compared. SD rats were treated with ISO (5 mg/kg/day) subcutaneously (s.c.) for 14 days, ASG (10 mg/kg/d) and Astragalus extract (AE) (4.35 g/kg/d, which contained about ASG 10 mg) were given p.o. from the 6th day of the modeling. Cardiac fibroblasts (CFs) of neonatal rats were incubated with ISO (10 µM) and treated with ASG (10 µM) simultaneously for 24 h. RESULTS: The results showed that both AE and ASG treatment reduced the TRPM7 expression from the gene level and inhibited cardiac fibrosis. ASG group showed similar potency as the AE mixture. ASG treatment significantly decreased the current, mRNA and protein expression of TRPM7 which was one of targets of miR-135a. The activation of TGF-ß/Smads pathway was suppressed and the expression of α-SMA and Collagen I were also decreased obviously. In addition, our results showed that there was a positive feedback between the activation of TGF-ß/Smads pathway and the elevation of TRPM7, both of which could promote the development of myocardial fibrosis. CONCLUSIONS: AE had the effect of cardiac fibrosis inhibition and decreased the mRNA expression of TRPM7. ASG, as one of the effective ingredients of AE, showed the same potency when given the same dose. ASG inhibited cardiac fibrosis by targeting the miR-135a-TRPM7-TGF-ß/Smads pathway.

Clinical, biochemical and genetic spectrum of 70 patients with ACAD9 deficiency: is riboflavin supplementation effective?

BACKGROUND: Mitochondrial acyl-CoA dehydrogenase family member 9 (ACAD9) is essential for the assembly of mitochondrial respiratory chain complex I. Disease causing biallelic variants in ACAD9 have been reported in individuals presenting with lactic acidosis and cardiomyopathy. RESULTS: We describe the genetic, clinical and biochemical findings in a cohort of 70 patients, of whom 29 previously unpublished. We found 34 known and 18 previously unreported variants in ACAD9. No patients harbored biallelic loss of function mutations, indicating that this combination is unlikely to be compatible with life. Causal pathogenic variants were distributed throughout the entire gene, and there was no obvious genotype-phenotype correlation. Most of the patients presented in the first year of life. For this subgroup the survival was poor (50% not surviving the first 2 years) comparing to patients with a later presentation (more than 90% surviving 10 years). The most common clinical findings were cardiomyopathy (85%), muscular weakness (75%) and exercise intolerance (72%). Interestingly, severe intellectual deficits were only reported in one patient and severe developmental delays in four patients. More than 70% of the patients were able to perform the same activities of daily living when compared to peers. CONCLUSIONS: Our data show that riboflavin treatment improves complex I activity in the majority of patient-derived fibroblasts tested. This effect was also reported for most of the treated patients and is mirrored in the survival data. In the patient group with disease-onset below 1 year of age, we observed a statistically-significant better survival for patients treated with riboflavin.

An infant case of diffuse cerebrospinal lesions and cardiomyopathy caused by a BOLA3 mutation.

INTRODUCTION: Mitochondrial dysfunction results in a wide range of organ disorders through diverse genetic abnormalities. We herein present the detailed clinical course of an infant admitted for extensive, rapidly progressing white matter lesions and hypertrophic cardiomyopathy due to a BOLA3 gene mutation. CASE: A 6-month-old girl with no remarkable family or past medical history until 1 month prior presented with developmental regression and feeding impairment. Ultrasound cardiography and brain magnetic resonance imaging (MRI) respectively disclosed the presence of hypertrophic cardiomyopathy and symmetrical deep white matter lesions. She was transferred to our hospital at age 6 months. High lactate levels in her cerebrospinal fluid suggested mitochondrial dysfunction. Despite vitamin supplementation therapy followed by a ketogenic diet, the patient began exhibiting clusters of myoclonic seizures and respiratory failure. Brain and spinal cord MRI revealed rapid progression of the white matter lesions. She died at 10 months of age. Fibroblasts obtained pre-mortem displayed low mitochondrial respiratory chain complex I and II activity. A homozygous H96R (c. 287 A > G) mutation was identified in the BOLA3 gene. DISCUSSION: No reported case of a homozygous BOLA3 gene mutation has survived past 1 year of life. BOLA3 appears to play a critical role in the electron transport system and production of iron-sulfur clusters that are related to lipid metabolism and enzyme biosynthesis.

Hypertrophic cardiomyopathy. / Miocardiopatía hipertrófica.

Hypertrophic cardiomyopathy is the most common inherited cardiovascular disease. It is characterized by increased ventricular wall thickness and is highly complex due to its heterogeneous clinical presentation, several phenotypes, large number of associated causal mutations and broad spectrum of complications. It is caused by mutations in sarcomeric proteins, which are identified in up to 60% of cases of the disease. Clinical manifestations of Hypertrophic Cardiomyopathy include shortness of breath, chest pain, palpitations and syncope, which are related to the onset of diastolic dysfunction, left ventricular outflow tract obstruction, ischemia, atrial fibrillation and abnormal vascular responses. It is associated with an increased risk of sudden cardiac death, heart failure and thromboembolic events. In this article, we discuss the diagnostic and therapeutic aspects of this disease.

Tanshinone IIA Inhibits ß-Catenin Nuclear Translocation and IGF-2R Activation via Estrogen Receptors to Suppress Angiotensin II-Induced H9c2 Cardiomyoblast Cell Apoptosis.

Cardiomyopathy involves changes in the myocardial ultra-structure, hypertrophy, apoptosis, fibrosis and inflammation. Angiotensin II (AngII) stimulates the expression of insulin like-growth factors (IGF-2) and IGF-2 receptor (IGF-2R) in H9c2 cardiomyoblasts and subsequently leads to apoptosis. Estrogen receptors protect cardiomyocytes from apoptosis and fibrosis. Tanshinone IIA (TSN), a main active ingredient from Danshen, has been shown to protect cardiomyocytes from death caused by different stress signals. Estrogen receptor α (ER) is required for the rapid activation of the IGF-1R signaling cascade. This study aimed to investigate whether TSN protected H9c2 cardiomyocytes from AngII-induced activation of IGF-2R pathway and hypertrophy via ERs. We found that AngII caused the reduction in IGF-1R phosphorylation and the elevation of ß-catenin and IGF-2R levels. This was reversed by increasing doses of TSN and of caspase-3 and ERK1/2 phosphorylation mediated by ERs. The phytoestrogen significantly attenuated AngII-induced apoptosis and suppressed the subsequent cardiac remodeling effect. Therefore, TSN reduced the AngII-induced activation of ß-catenin and IGF-2R pathways, apoptosis and cardiac remodeling via ERs in H9c2 cardiomyoblasts.

Energy utilization of induced pluripotent stem cell-derived cardiomyocyte in Fabry disease.

BACKGROUND: Fabry disease (FD) is a lysosomal storage disease in which glycosphingolipids (GB3) accumulate in organs of the human body, leading to idiopathic hypertrophic cardiomyopathy and target organ damage. Its pathophysiology is still poorly understood. OBJECTIVES: We aimed to generate patient-specific induced pluripotent stem cells (iPSC) from FD patients presenting cardiomyopathy to determine whether the model could recapitulate key features of the disease phenotype and to investigate the energy metabolism in Fabry disease. METHODS: Peripheral blood mononuclear cells from a 30-year-old Chinese man with a diagnosis of Fabry disease, GLA gene (IVS4+919G>A) mutation were reprogrammed into iPSCs and differentiated into iPSC-CMs and energy metabolism was analyzed in iPSC-CMs. RESULTS: The FD-iPSC-CMs recapitulated numerous aspects of the FD phenotype including reduced GLA activity, cellular hypertrophy, GB3 accumulation and impaired contractility. Decreased energy metabolism with energy utilization shift to glycolysis was observed, but the decreased energy metabolism was not modified by enzyme rescue replacement (ERT) in FD-iPSCs-CMs. CONCLUSION: This model provided a promising in vitro model for the investigation of the underlying disease mechanism and development of novel therapeutic strategies for FD. This potential remedy for enhancing the energetic network and utility efficiency warrants further study to identify novel therapies for the disease.

Omega-3-fatty acid adds to the protective effect of flax lignan concentrate in pressure overload-induced myocardial hypertrophy in rats via modulation of oxidative stress and apoptosis.

Objective of the present investigation was to study the effect of the flax lignan concentrate (FLC) and Omega-3-fatty acid (O-3-FA) on myocardial apoptosis, left ventricular (LV) contractile dysfunction and electrocardiographic abnormalities in pressure overload-induced cardiac hypertrophy. The rats were divided into five groups such as sham, aortic stenosis (AS), AS+FLC, AS+O-3-FA and AS+FLC+O-3-FA. Cardiac hypertrophy was produced in rats by abdominal aortic constriction. The rats were treated with FLC (400mg/kg, p.o.), O-3-FA (400mg/kg, p.o.) and FLC+O-3-FA orally per day for four weeks. The LV function, myocardial apoptosis, and oxidative stress were quantified. FLC+O-3-FA treatment significantly reduced hemodynamic changes, improved LV contractile dysfunction, reduced cardiomyocyte apoptosis and cellular oxidative stress. Moreover, it significantly up-regulated the VEGF expression and decreased TNF-alpha level in serum. The histological analysis also revealed that FLC+O-3-FA treatment markedly preserved the cardiac structure and inhibited interstitial fibrosis. In conclusion, FLC+O-3-FA treatment improved LV dysfunction, inhibited cardiomyocyte apoptosis, improved myocardial angiogenesis, conserved activities of membrane-bound phosphatase enzymes and suppressed inflammation through reduced oxidative stress in an additive manner than FLC alone and O-3-FA alone treatment in pressure overload-induced cardiac hypertrophy.

Obstructive heart defects associated with candidate genes, maternal obesity, and folic acid supplementation.

Right-sided and left-sided obstructive heart defects (OHDs) are subtypes of congenital heart defects, in which the heart valves, arteries, or veins are abnormally narrow or blocked. Previous studies have suggested that the development of OHDs involved a complex interplay between genetic variants and maternal factors. Using the data from 569 OHD case families and 1,644 control families enrolled in the National Birth Defects Prevention Study (NBDPS) between 1997 and 2008, we conducted an analysis to investigate the genetic effects of 877 single nucleotide polymorphisms (SNPs) in 60 candidate genes for association with the risk of OHDs, and their interactions with maternal use of folic acid supplements, and pre-pregnancy obesity. Applying log-linear models based on the hybrid design, we identified a SNP in methylenetetrahydrofolate reductase (MTHFR) gene (C677T polymorphism) with a main genetic effect on the occurrence of OHDs. In addition, multiple SNPs in betaine-homocysteine methyltransferase (BHMT and BHMT2) were also identified to be associated with the occurrence of OHDs through significant main infant genetic effects and interaction effects with maternal use of folic acid supplements. We also identified multiple SNPs in glutamate-cysteine ligase, catalytic subunit (GCLC) and DNA (cytosine-5-)-methyltransferase 3 beta (DNMT3B) that were associated with elevated risk of OHDs among obese women. Our findings suggested that the risk of OHDs was closely related to a combined effect of variations in genes in the folate, homocysteine, or glutathione/transsulfuration pathways, maternal use of folic acid supplements and pre-pregnancy obesity.

Mutations in COA6 cause cytochrome c oxidase deficiency and neonatal hypertrophic cardiomyopathy.

COA6/C1ORF31 is involved in cytochrome c oxidase (complex IV) biogenesis. We present a new pathogenic COA6 variant detected in a patient with neonatal hypertrophic cardiomyopathy and isolated complex IV deficiency. For the first time, clinical details about a COA6-deficient patient are given and patient fibroblasts are functionally characterized: COA6 protein is undetectable and steady-state levels of complex IV and several of its subunits are reduced. The monomeric COX1 assembly intermediate accumulates. Using pulse-chase experiments, we demonstrate an increased turnover of mitochondrial encoded complex IV subunits. Although monomeric complex IV is decreased in patient fibroblasts, the CI/CIII2 /CIVn -supercomplexes remain unaffected. Copper supplementation shows a partial rescue of complex IV deficiency in patient fibroblasts. We conclude that COA6 is required for complex IV subunit stability. Furthermore, the proposed role in the copper delivery pathway to complex IV subunits is substantiated and a therapeutic lead for COA6-deficient patients is provided.

Serum supplemented culture medium masks hypertrophic phenotypes in human pluripotent stem cell derived cardiomyocytes.

It has been known for over 20 years that foetal calf serum can induce hypertrophy in cultured cardiomyocytes but this is rarely considered when examining cardiomyocytes derived from pluripotent stem cells (PSC). Here, we determined how serum affected cardiomyocytes from human embryonic- (hESC) and induced pluripotent stem cells (hiPSC) and hiPSC from patients with hypertrophic cardiomyopathy linked to a mutation in the MYBPC3 gene. We first confirmed previously published hypertrophic effects of serum on cultured neonatal rat cardiomyocytes demonstrated as increased cell surface area and beating frequency. We then found that serum increased the cell surface area of hESC- and hiPSC-derived cardiomyocytes and their spontaneous contraction rate. Phenylephrine, which normally induces cardiac hypertrophy, had no additional effects under serum conditions. Likewise, hiPSC-derived cardiomyocytes from three MYBPC3 patients which had a greater surface area than controls in the absence of serum as predicted by their genotype, did not show this difference in the presence of serum. Serum can thus alter the phenotype of human PSC derived cardiomyocytes under otherwise defined conditions such that the effects of hypertrophic drugs and gene mutations are underestimated. It is therefore pertinent to examine cardiac phenotypes in culture media without or in low concentrations of serum.

Early myoclonic epilepsy, hypertrophic cardiomyopathy and subsequently a nephrotic syndrome in a patient with CoQ10 deficiency caused by mutations in para-hydroxybenzoate-polyprenyl transferase (COQ2).

BACKGROUND: Primary coenzyme Q10 (CoQ10) deficiencies are heterogeneous autosomal recessive disorders. CoQ2 mutations have been identified only rarely in patients. All affected individuals presented with nephrotic syndrome in the first year of life. METHODS: An infant is studied with myoclonic seizures and hypertrophic cardiomyopathy in the first months of life and developed a nephrotic syndrome in a later stage. RESULTS: At three weeks of age, the index patient developed myoclonic seizures. In addition, he had hypertrophic cardiomyopathy and increased CSF lactate. A skeletal muscle biopsy performed at two months of age disclosed normal activities of the oxidative phosphorylation complexes. The child was supplemented with CoQ10 (5 mg/kg/day). At the age of four months, brain MR images showed bilateral increased signal intensities in putamen and cerebral cortex. After that age, he developed massive proteinuria. The daily dose of CoQ10 was increased to 30 mg/kg. Renal biopsy showed focal segmental glomerulosclerosis. Biochemical analyses of a kidney biopsy sample revealed a severely decreased activity of succinate cytochrome c reductase [complex II + III] suggesting ubiquinone depletion. Incorporation of labelled precursors necessary for CoQ10 synthesis was significantly decreased in cultured skin fibroblasts. His condition deteriorated and he died at the age of five months. A novel homozygous mutation c.326G > A (p.Ser109Asn) was found in COQ2. CONCLUSIONS: In contrast to previously reported patients with CoQ2 the proband presented with early myoclonic epilepsy, hypertrophic cardiomyopathy and only in a later stage developed a nephrotic syndrome. The phenotype of this patient enlarges the phenotypical spectrum of the multisystem infantile variant.

[Effects of ligustrazine on the mitochondrial structure and functions in the process myocardial hypertrophy].

OBJECTIVE: To explore changes of mitochondrial structure and functions, as well as the protection of ligustrazine in the process of myocardial hypertrophy. METHODS: Neonatal myocardial cells were isolated and cultured with angiotensin II (Ang II) for 72 or 96 h. The total protein content was detected using BCA method. The cell diameter was measured by inverted microscope, by which to reflect the proliferation situation of cardiomyocytes. The mitochondrial membrane potential (MMP) was measured by fluorescence microscope. The mitochondrial monoamine oxidase (MAO) activity was detected by spectrophotometer. The mitochondrial cytochrome oxidase (COX) activity and the mitochondrial damage percentage were detected by microplate reader, by which to reflect the damage of mitochondrial outer membrane's structure and the membranes' function. Also, cells were treated with ligustrazine and losartan and then the pharmacological effects on the mitochondrial structure and functions in the myocardial cells treated with Ang II were observed. RESULTS: At 72 h and 96 h, when compared with the blank group, cells treated with Ang II had increased total protein content (P < 0.01) and enlarged diameter (P < 0.01). Treated with Ang II, the MAO activity and the outer membrane damage percentage of myocardial cells significantly increased (P < 0.01), and mitochondrial COX activity and the mitochondrial MMP significantly decreased (P < 0.01). Compared with the model group at the same time period, ligustrazine significantly reduced myocardial cells' total protein content and myocardial cell diameter, and significantly decreased myocardial cells' MAO activity, increased mitochondrial COX activity, improved the outer membrane damage percentage and inner membrane MMP at 72 and 96 h, all showing statistical difference (P < 0.01, P < 0.05). CONCLUSIONS: During the process of myocardial hypertrophy existed the damage to the mitochondrial structure and functions. Ligustrazine protected the mitochondrial structure and functions of the myocardial cells in reversing Ang II induced myocardial cell hypertrophy.

[Semen descurainiae inhibits CYP11B1, CYP11B2 and TGF-beta1 mRNA expression in left ventricular].

OBJECTIVE: To investigate the effects of Semen descurainiae and Captopril on CYP11B1, CYP11B2 and TGF-beta1 mRNA expression of heart tissue in rats treated with Abdominal Aortic Banding. METHODS: Ventricular remodeling was induced by abdominal aortic banding (AAB) in rats. After 30 days' treatment, the ratios of LVW/BW (left ventricle weight/body weight), HW/BW (heart weight/body weight) were calculated; Then the CYP11B, CYP11B2 and TGF-beta1 mRNA expression of left ventricle were detected by Real-time PCR, respectively. RESULTS: The experimental data demonstrated that Semen descurainiae decreased the indexes of LVW/BW and HW/BW, down-regulated CYP11B, CYP11B2 and TGF-beta1 mRNA expression in left ventricle (P<0.05). CONCLUSION: Semen desceurainiae can significantly inhibit the experimental ventricular remodeling; the mechanism is related to its ability to attenuate the mRNA expression of CYP11B1, CYP11B2 and TGF-beta1 in left ventricle. The inhibition of aldosterone key gene expression by Semen descurainiae may contribute to its effect on restraint cardiac remodeling.