Molecular genetics of familial hypertrophic cardiomyopathy (FHC)

 Familial hypertrophic cardiomyopathy is an autosomal dominant disease with a wide range of clinical features from benign to severe, and is the most common cause of sudden death in otherwise healthy individuals. The two prominent clinical features are left ventricular hypertrophy and myocyte/myofibrillar disarray. The former is responsible for clinical symptoms such as breathlessness and angina, whereas the latter may lead to sudden cardiac death. The last decade has seen an enormous improvement in our understanding of the molecular genetics of this disorder. The clinical heterogeneity has been linked to genetic heterogeneity; mutations in nine genes encoding sarcomere proteins have been shown to be the molecular basis for the disorder. However, attempts to establish a genotype–phenotype correlation for each of the more than 100 mutations that have been identified have not been highly successful. Additional genetic loci, as well as nongenetic factors such as lifestyle, sex, and age, have also been shown to play a role in modulating the clinical presentation of the disease. How each mutation results in hypertrophy and/or myofibrillar disarray is unclear. The present review discusses the current status of the molecular genetic characterization of this important disorder. Received: October 15, 2002 / Accepted: November 18, 2002 Correspondence to:M.D. Bashyam     

The role of a common TNNT2 polymorphism in cardiac hypertrophy

We found a five-basepair insertion/deletion polymorphism in intron 3 of TNNT2, one of the genes responsible for hypertrophic cardiomyopathy. These five bases may be part of an intronic polypyrimidine tract sequence that may affect splicing. The purpose of the study was to examine the association of the polymorphism with cardiac hypertrophy. The study population consisted of 151 subjects with prominent concentric left ventricular hypertrophy, and 987 healthy subjects recruited from medical checkups (control population). The deletion/deletion genotype tended to be associated with a larger left ventricular mass/height ratio in the HCM population (p<0.0001). Multiple regression analyses indicated that the left ventricular mass/height ratio was determined (p<0.0001, R=0.738) by the TNNT2 genotype. Moreover, the frequency of the deletion allele was significantly higher in the hypertrophy population than in the control population (p<0.0001). In vitro expression study revealed the deletion allele significantly affected the mRNA expression pattern by skipping exon 4 during splicing. In conclusion, TNNT2 deletion allele could be associated with a predisposition to prominent left ventricular hypertrophy.The first two authors contributed equally to this study.     

Lack of reliable clinical predictors to identify obstructive sleep apnea in patients with hypertrophic cardiomyopathy

OBJECTIVE:

Obstructive sleep apnea is common among patients with hypertrophic cardiomyopathy and may contribute to poor cardiovascular outcomes. However, obstructive sleep apnea is largely unrecognized in this population. We sought to identify the clinical predictors of obstructive sleep apnea among patients with hypertrophic cardiomyopathy.

METHODS:

Consecutive patients with hypertrophic cardiomyopathy were recruited from a tertiary University Hospital and were evaluated using validated sleep questionnaires (Berlin and Epworth) and overnight portable monitoring. Ninety patients (males, 51%; age, 46±15 years; body mass index, 26.6±4.9 kg/m²) were included, and obstructive sleep apnea (respiratory disturbance index ≥15 events/h) was present in 37 patients (41%).

RESULTS:

Compared with the patients without obstructive sleep apnea, patients with obstructive sleep apnea were older and had higher body mass index, larger waist circumference, larger neck circumference, and higher prevalence of atrial fibrillation. Excessive daytime sleepiness (Epworth scale) was low and similar in the patients with and without obstructive sleep apnea, respectively. The only predictors of obstructive sleep apnea (using a logistic regression analysis) were age ≥45 years (odds ratio [OR], 4.46; 95% confidence interval [CI 95%], 1.47–13.54; p = 0.008) and the presence of atrial fibrillation [OR, 5.37; CI 95%, 1.43–20.12; p = 0.013].

CONCLUSION:

Consistent clinical predictors of obstructive sleep apnea are lacking for patients with hypertrophic cardiomyopathy, which suggests that objective sleep evaluations should be considered in this population, particularly among elderly patients with atrial fibrillation.     

Congestive heart failure due to mitochondrial cardiomyopathy in kearns-sayre syndrome

Summary Despite extensive analysis of the ultrastructural changes in skeletal muscle fibers in chronic progressive external ophthalmoplegia (CPEO), similar changes in the heart muscle fibers of patients with cardiac involvement in CPEO, called Kearns-Sayre syndrome, have not been described in detail. We report the clinical long-term course in a patient with Kearns-Sayre syndrome in whom mitochondrial cardiomyopathy was suspected in vivo and was confirmed at autopsy as the underlying cause of severe dilative cardiomyopathy. Enlarged, abnormally structured, excessively augmented mitochondria and loss of myofibrils could be shown both in skeletal and heart muscle cells.Abbreviations CPEO chronic progressive external ophthalmoplegia - EMG electromyogram - ENT department ear, nose, and throat department - LAH left anterior hemiblock - LVEDP left ventricular end-diastolic pressure - LVEDVI left ventricular end-diastolic volume index - LVEF left ventricular ejection fraction - LVESVI left ventricular end-systolic volume index - PAP pulmonary artery pressure - RAP right arterial pressure Supported by the Dr. Sepp and Hanne-Sturm-Stiftung     

A deregulated immune response to gliadin causes a decreased villus height in DQ8 transgenic mice

Celiac disease (CD) is an enteropathy triggered by gluten and mediated by CD4⁺T cells. A complete understanding of CD immunopathogenesis has been hindered due to the lack of adequate in vivo models. Here, we explored the effect of the inhibition of COX by indomethacin in wheat gliadin‐sensitized transgenic mice expressing the HLA‐DQ8 heterodimer, a molecule associated with CD. Treated mice showed a gliadin‐specific immune response with a significant reduction of villus height, not linked to crypt hyperplasia and to expansion of intraepithelial T cells. Notably, treated mice showed increased numbers of CD25⁺ and apoptotic cells in the lamina propria, whereas high basal levels of IFN‐γ secretion, along with a reduced gliadin‐specific IL‐2 expression were detected in MLN. Biochemical assessment of the lesion revealed increased mRNA of Lamb3 and Adamts2, encoding for ECM proteins, and enhanced activities of metalloproteinases MMP1, 2 and 7. We conclude that an intestinal sensitivity to gliadin, in connection with COX inhibition, caused a decreased villus height in DQ8 tg mice. The lesion was induced by a deregulated mucosal cell immunity to gliadin, thus triggering activation of a specific ECM protein pathway responsible for lamina propria remodeling.     

Clinical and biochemical spectrum of metabolic cardiomyopathy in Egyptian children

BackgroundInborn errors of metabolism (IEMs) commonly present with pediatric cardiomyopathy. Identification of the underlying cause is necessary as it may lead to improved outcomes.ObjectivesWe aimed to investigate the diagnostic rate, the clinical, and biochemical spectra of IEMs among Egyptian pediatric patients presenting with cardiomyopathy, and their outcome measures.MethodsWe retrospectively analyzed the clinical, biochemical, and radiological data of 1512 children diagnosed with cardiomyopathy at Cairo University Children''s Hospital over a 5-year duration.ResultsTwo hundred twenty-nine children were clinically suspected as IEMs and underwent metabolic workup. Nineteen different IEMs were confirmed in 57 (24.4%) of the suspected children. Their median age at presentation was 2.6 years and the majority had extra-cardiac manifestations. Hypertrophic cardiomyopathy represented 43/57 (75.4%) of confirmed cases, while dilated cardiomyopathy represented 13/57 (22.8%), and one patient presented with a mixed phenotype. Twenty- six patients (45.6%) survived, while 31 patients (54%) either died or were lost to follow up and assumed deceased.ConclusionsWe developed for the first time a database and a diagnostic scheme for metabolic cardiomyopathies in Egyptian children. With the recent introduction of enzyme replacement therapy, many metabolic disorders became treatable, thus establishing an early and accurate diagnosis is extremely important.     

Neuronal driven pre-plaque inflammation in a transgenic rat model of Alzheimer's disease

Chronic brain inflammation is associated with Alzheimer's disease (AD) and is classically attributed to amyloid plaque deposition. However, whether the amyloid pathology can trigger early inflammatory processes before plaque deposition remains a matter of debate. To address the possibility that a pre-plaque inflammatory process occurs, we investigated the status of neuronal, astrocytic, and microglial markers in pre- and post-amyloid plaque stages in a novel transgenic rat model of an AD-like amyloid pathology (McGill-R-Thy1-APP). In this model, we found a marked upregulation of several classical inflammatory markers such as COX-2, IL-1β, TNF-α, and fractalkine (CX3CL1) in the cerebral cortex and hippocampus. Interestingly, many of these markers were highly expressed in amyloid beta-burdened neurons. Activated astrocytes and microglia were associated with these Aβ-burdened neurons. These findings confirm the occurrence of a proinflammatory process preceding amyloid plaque deposition and suggest that Aβ-burdened neurons play a crucial role in initiating inflammation in AD.     

Large-scale mutation screening in patients with dilated or hypertrophic cardiomyopathy: a pilot study using DGGE

Cardiomyopathies are complex myocardial diseases characterized by inappropriate ventricular hypertrophy (HCM) or dilation (DCM). Both disorders may lead to sudden death or progressive heart failure and exhibit familial aggregation with marked genetic heterogeneity. Many candidate genes were identified by linkage analysis, experimental animal studies, and expression analysis. A systematic assessment of the prevalence of different mutations in these genes requires high-throughput analyses. In this paper, we present a simple and reliable protocol for mutation screening by heteroduplex analysis which reduced costs and workload of sequencing. Employing denaturing gradient gel electrophoresis (DGGE), 11 known and 14 potential candidate genes for HCM and DCM were analyzed. DGGE assays allowed analysis of 286 of the 312 protein coding exons, performing only four alternative polymerase chain reaction protocols and only two different DGGE analysis conditions. Sensitivity for the detection of heteroduplexes proved excellent, even for GC-rich DNA fragments, which were analyzed by a combination of DGGE and constant denaturant gel electrophoresis. To confirm DGGE sensitivity in cases where no variants in our human DNA samples could be observed, we generated heteroduplexes from homologous human and chimpanzee DNA. The platform proved a valuable contribution to elucidating the genetic causes of DCM and HCM as demonstrated by the identification of 17 different known and novel mutations and 98 different polymorphisms in our setting.Electronic Supplementary Material Supplementary material is available in the online version of this article at     

Spontaneous closure of iatrogenic coronary artery fistula to left ventricle after septal myectomy for hypertrophic obstructive cardiomyopathy

Cases of iatrogenic coronary artery fistulas draining into the left ventricle after surgical myectomy for hypertrophic obstructive cardiomyopathy have been published as sporadic reports. However, its management scheme and prognosis are not clear because of the low incidence. A 46-yr-old woman was hospitalized for evaluation of chest pain and shortness of breath for 3 months. Transthoracic echocardiographic examination showed typical hypertrophic obstructive cardiomyopathy with a peak pressure gradient of 71 mmHg across the left ventricular outflow tract. The patient underwent surgical septal myectomy. Postoperative color Doppler imaging revealed a diastolic blood flow from the interventricular septal myocardium to the left ventricular cavity, i.e. iatrogenic coronary artery fistula to the left ventricle. Ten days later, the fistula closed spontaneously which was diagnosed by transthoracic echocardiography and confirmed by coronary angiography.     

Prion-like acceleration of a synucleinopathy in a transgenic mouse model

Our aim in this study was to investigate experimentally the possible in vivo transmission of a synucleinopathy, using a transgenic mouse model (TgM83) expressing the human A53T mutated α-synuclein. Brain homogenates from old TgM83 mice showing motor clinical signs due to the synucleinopathy and containing insoluble and phosphorylated (pSer129) α-synuclein were intracerebrally inoculated in young TgM83 mice. This triggered an early onset of characteristic motor clinical signs, compared with uninoculated TgM83 mice or to mice inoculated with a brain homogenate from a young, healthy TgM83 mouse. This early disease was associated with insoluble α-synuclein phosphorylated on Ser129, as already identified in old and sick uninoculated TgM83 transgenic mice. Although the molecular mechanisms remain to be determined, acceleration of the pathology following inoculation of mice expressing human mutated α-synuclein with tissues from mice affected by the synucleinopathy, could be consistent with "prion-like" propagation of the disease.     

肥大心肌细胞缺氧复氧损伤特点及干预能量代谢的作用

目的：探讨肥大心肌细胞缺氧复氧损伤与能量代谢途径转换的关系。 方法: 应用血管紧张素Ⅱ (AngⅡ, 0.1 μmol/L)+去甲肾上腺素（NE 1 μmol/L）诱导培养大鼠心肌细胞肥大，以同位素液闪计数法测定葡萄糖有氧氧化率（GOR）、葡萄糖酵解率（GLR）和脂肪酸有氧氧化率（FOR），TUNEL法测定细胞凋亡。 结果: (1)常氧培养时，肥大心肌细胞的葡萄糖氧化率（GOR）、糖酵解率（GLR）均高于正常心肌细胞，而脂肪酸氧化率（FOR）低于正常心肌细胞，但与细胞凋亡率一样，与正常心肌细胞比较无显著差异。(2)肥大心肌细胞缺氧6 h后细胞凋亡率显著高于缺氧前，复氧后不仅细胞凋亡更显著高于缺氧前，还出现了细胞坏死。(3)正常心肌细胞和肥大心肌细胞缺氧后GLR无明显变化，GOR、FOR均低于缺氧前，缺氧6 h时出现显著差异，但肥大心肌细胞GOR在缺氧2 h时即显著低于缺氧前。缺氧复氧后，正常心肌细胞和肥大心肌细胞GOR均低于对应单纯缺氧时间组，而GLR和FOR轻度高于对应单纯缺氧2 h组，在肥大心肌细胞均显著高于对应单纯缺氧时间组，并随缺氧时间延长更明显。(4)二氯乙酸（DCA）和曲美他嗪（TMZ）预处理后的肥大心肌细胞缺氧复氧后的GOR显著高于对应的无干预肥大心肌细胞组，GLR、FOR和细胞凋亡率均显著低于无干预肥大心肌细胞组。 结论: 肥大心肌细胞更易于受到缺氧复氧刺激的损伤，活化糖代谢可部分抑制这种损伤。     

Functional characterization of the human atrial essential myosin light chain (hALC-1) in a transgenic rat model

Most patients with hypertrophic cardiomyopathy and congenital heart diseases express the atrial essential myosin light chains (ALC-1) in their ventricles, partially replacing the ventricular essential light chains (VLC-1). This VLC-1/ALC-1 isoform shift is correlated with an increase in cross-bridge cycling kinetics as measured using skinned fibers from the hypertrophied ventricles of human hearts.To study the functional importance of hALC-1 in the intact perfused heart, we generated a transgenic rat model (TGR) overexpressing hALC-1 in the heart. Twelve-week-old TGR rats expressed 17±4 g hALC-1 per mg of whole SDS-soluble protein. Their perfused heart contractility parameters were evaluated using the Langendorff preparation. Expression of hALC-1 was accompanied by statistically significant improvements (P<0.001) in the contractile parameters of the hearts of the TGR compared to the age matched control (WKY) animals, represented by increases from 20.8±2.3 to 45.1±3.6 mmHg/g heart weight in the developed left ventricular pressure, 1,035.7±89.8 to 2,181±135.4 mmHg/s in the contraction rate, and 713±60.2 to 1,364±137.4 mmHg/s in the relaxation rate in the WKY and the TGR groups respectively. Characterizing the functional effects of hALC-1 at the whole organ level represents a step towards gene therapy of heart failure.     

Dopaminergic differentiation of grafted GFP transgenic neuroepithelial stem cells in the brain of a rat model of Parkinson's disease

Neuroepithelial stem cells (NEPs) possess multipotent potential for self-renewal and neuronal differentiation. Using green fluorescent protein (GFP) positive NEPs, we explored, firstly, the survival and differentiation of grafted NEPs in the host rat and, secondly, whether or not transplantation of NEPs is a feasible therapeutic option for treating Parkinson's disease. NEPs were harvested from the neural tube of enhanced GFP transgenic embryos. In culture, GFP(+) NEPs generated abundant neurospheres and differentiated into both neurons and glia. When stereotaxically transplanted into the 6-hydroxydopamine (6-OHDA)-lesioned striatum of rats, NEPs survived and tyrosine hydroxylase (TH)-positive cells were detected in the graft. Furthermore, these grafted GFP(+) NEPs significantly ameliorated Parkinsonian behavioral symptoms compared with controls which were treated only with normal saline. Our results suggest that transplanted NEPs accomplish dopaminergic differentiation may be used for treating Parkinson's disease.     

改良Morrow术治疗梗阻性肥厚型心肌病的治疗效果及围手术期护理要点

目的 探讨采用改良Morrow术治疗梗阻性肥厚型心肌病(HOCM)患者的治疗效果及围手术期护理要点.方法 选择首都医科大学附属北京安贞医院2016年1月至2017年1月收治的35例行改良Morrow术治疗HOCM患者.术前对患者进行心理护理,完善相关检查,指导患者进行呼吸锻炼,术中护士不应离开手术室,术后密切观察患者心...     

Lysosomal and energy enzyme activities in hypertrophied rat soleus muscle after denervation

Muscle hypertrophy was induced in the soleus muscle of young rats by tenotomy of the gastrocnemius and plantaris muscles. Three and 7 days afterwards the sciatic nerve was sectioned. The loss of weight of muscles subjected to this combined procedure three days after denervation was 30–40%. Lysosomal enzyme activities (acid phosphatase, -glucosidase, -galactosidase and N-acetyl--d-glucosaminidase) and energy enzyme activities (lactate dehydrogenase, LDH, triose-3-phosphate dehydrogenase, TPDH,d-hexokinase, HK and citrate synthase, CS) were determined 3 days after denervation, 3, 7 and 10 days after hypertrophy had been induced and 3 days after denervation of hypertrophying muscles on day 3 and 7. Normal non-operated rats of corresponding body wieght served as controls and their enzyme activities were estimated on the same day. In the course of muscle hypertrophy, the 4 lysosomal enzyme activities increased progressively. Although 3 days' denervation of control muscles did not alter lysomal enzyme activities, denervation of hypertrophying muscles greatly enhanced the activity of these enzymes. Enzymes of energy metabolism were affected to a lesser degree. The results suggest that denervation of hypertrophying muscles causes more extreme changes in muscle weight and lysosomal enzyme activities than denervation alone. The possible implications of this finding are discussed in relation to the rapid atrophy.     

Development of apical hypertrophic cardiomyopathy with age in a transgenic mouse model carrying the cardiac actin E99K mutation

In both humans and mice, the Glu-99-Lys (E99K) mutation in the cardiac actin gene (ACTC) results in little understood apical hypertrophic cardiomyopathy (AHCM). To determine how cross-bridge kinetics change with AHCM development, we applied sinusoidal length perturbations to skinned papillary muscle fibres from 2- and 5-month old E99K transgenic (Tg) and non-transgenic (NTg) mice, and studied tension and its transients. These age groups were chosen because our preliminary studies indicated that AHCM develops with age. Fibres from 5-month old E99K mice showed significant decreases in tension, stiffness, the rate of the medium-speed exponential process and its magnitude compared to non-transgenic control. The nucleotide association constants increased with age, and they were significantly larger in E99K compared to NTg. However, there were no large differences in the rates of the cross-bridge detachment step, the rates of the force generation step, or the phosphate association constant. Our result on force/cross-bridge demonstrates that the decreased active tension of E99K fibres was caused by a decreased amount of force generated per each cross-bridge. The effects were generally less or insignificant at 2 months. A pCa-tension study showed increased Ca²⁺-sensitivity (pCa₅₀) with age in both the E99K and NTg sample groups, and pCa₅₀ was significantly larger (but only for 0.05–0.06 pCa units) in E99K than in NTg groups. A significant decrease in cooperativity (n_H) was observed only in 5-month old E99K mice. We conclude that the AHCM-causing ACTC E99K mutation is associated with progressive alterations in biomechanical parameters, with changes smaller at 2 months but larger at 5 months, correlating with the development of AHCM.     

Thymic epithelial tumour progression in an SV40T transgenic mouse model

 There have been several reports that thymoma in human is a progressive disease, and that thymoma and thymic carcinoma form a continuum. We established a stable line of SV40T transgenic mice, which consistently produced thymic epithelial tumours progressing to thymic carcinoma within a predictable time span. Using this animal model and a morphological approach, thymic epithelial tumour progression was studied with reference to sequential changes at different time points in animals aged from 3 to 32 weeks. At all ages, SV40T was expressed in the nuclei of thymic epithelial cells; in these transgenic mice we observed the entire spectrum from cortical type thymoma to thymic carcinoma. Thymic size tended to increase with ageing in SV40T TG mice. While younger mice had predominantly cortical (organoid) or cortical thymoma, older mice had well-differentiated thymic carcinoma (WDTC) or poorly differentiated thymic carcinoma. When SV40T TG mice (248 line) reached a certain age, carcinoma of the thymus was present in all of them. Cortical-type thymoma became malignant within a predictable time span, suggesting a cortical thymoma–carcinoma sequence. When the mice were 9 weeks of age, the thymuses formed gross masses compatible with cortical thymoma. At 14 weeks of age, WDTC appeared against the background of cortical thymoma. Poorly differentiated thymic carcinoma was found after 15 weeks and affected all animals over 23 weeks of age. Most thymic carcinomas coexisted in varying proportions with cortical-type thymoma. Medullary thymomas did not develop in the mice, and no transition from medullary-type thymomas to thymic carcinomas was observed. In this SV40T transgenic mouse model, thymic carcinoma is clearly preceded by cortical-type thymoma. These transgenic mice may provide an interesting model for the progression from cortical thymoma to WDTC and/or high-grade carcinoma. Received: 6 August 1996 / Accepted: 23 June 1997     

Cassette vectors directing expression of T cell receptor genes in transgenic mice

We describe a pair of cassette vectors that can be used to express rearranged T cell receptor genes in transgenic mice. Short DNA fragments containing rearranged V and Vβ segments are readily amplified from T cells and introduced between artificial cloning sites. Transgene-derived mRNAs are transcribed under the control of the natural TCR and -β promoter/enhancer elements. Using this vector, we have obtained transgenic mouse lines which display transgene-encoded TCR and β chains on a majority of T cells.     

环孢素对癫痫大鼠海马氧化应激及线粒体能量代谢的影响

 目的：探讨环孢素对癫痫大鼠海马氧化应激、线粒体膜通透性及能量代谢的影响及机制。方法：应用匹鲁卡品建立癫痫持续状态模型,检测癫痫大鼠海马在环孢素干预前后丙二醛和超氧化物歧化酶的变化;检测癫痫大鼠海马在环孢素干预前后线粒体膜通透性转换、线粒体呼吸链复合物I和III活性及ATP含量的变化。结果：环孢素抑制癫痫大鼠海马组织线粒体膜通透性转换;明显降低癫痫大鼠海马组织丙二醛的含量,提高超氧化物歧化酶的活性（P<0.05）;明显增加癫痫大鼠海马组织线粒体呼吸链复合物I活性（P<0.05）,而对粒体呼吸链复合物III活性无显著影响;明显增加癫痫大鼠海马组织ATP的含量（P<0.05）。结论：环孢素能抑制癫痫大鼠海马氧化应激反应,减轻癫痫大鼠线粒体能量代谢损伤。     

急、慢性缺氧对大鼠脑线粒体能量代谢的影响

目的:探讨缺氧大鼠脑线粒体能量代谢的特点。方法:雄性Wistar大鼠随机分为急性缺氧组(AH)、慢性缺氧组(CH)和对照组。急、慢性缺氧组动物分别连续暴露于模拟4000m高原3d(AH)和40d(CH)。分离脑线粒体,分别测定线粒体呼吸功能、线粒体内腺苷酸池含量、ATP生成能力和F₀F₁-ATP酶活性。结果:急性缺氧大鼠IV态呼吸(ST₄)显著升高,伴呼吸控制率(RCR)降低,同时线粒体内ATP含量、ATP生成率和F₀F₁-ATP酶活性均显著降低;慢性缺氧大鼠ST₄、RCR、线粒体ATP含量和F₀F₁-ATP酶活性部分恢复。结论:急性缺氧脑线粒体代谢是以功能受损为特点,而慢性缺氧时则表现为功能的部分代偿。