Characterization of a novel missense mutation E637K in the pore-S6 loop of HERG in a patient with long QT syndrome

OBJECTIVE: In a 32-year-old woman with marked QT prolongation (QTc=0.61 s) and repeated episodes of syncope, we identified a single pertinent base substitution (G to A at 1909) in HERG by genetic analysis. This novel missense mutation is predicted to cause an amino acid substitution of lysine for glutamic acid at position 637 (E637K) in the pore-S6 loop. Therefore, we investigated the role of a glutamic acid at the vicinity of the pore in HERG channels by mutating it to a lysine. METHODS: We characterized the electrophysiological properties of the E637K mutation using a Xenopus oocyte heterologous expression system. RESULTS: Injection of the E637K mutant cRNA alone into Xenopus oocytes did not result in any expression of detectable currents. Coexpression of wild-type (WT) and E637K (E637K/WT) elicited only about 30% of the control peak tail current that was expected from expression of WT alone. Kinetic analyses revealed that E637K/WT decelerated the rate of channel activation and enhanced steady-state inactivation. Furthermore, the reversal potentials at low concentrations of K+ showed a positive shift in oocytes injected with E637K/WT compared with WT alone. CONCLUSIONS: These results indicated that the E637K mutation causes apparent dominant negative suppression of WT HERG channel function and suggest that E637 at the Pore-S6 is a crucial component of the activation and inactivation gate of HERG channels.     

A novel mutation Lys273Glu in the cardiac troponin T gene shows high degree of penetrance and transition from hypertrophic to dilated cardiomyopathy.

Familial hypertrophic cardiomyopathy (HC) can be caused by mutations in 9 different genes encoding sarcomere proteins expressed in cardiac muscle. To date, only 13 different mutations in the cardiac troponin T (cTnT) gene have been reported to cause HC. Clinical characteristics and prognosis associated with mutations of this gene have not been well characterized owing to the small size and composition of affected families. The aim of this study was to determine the characteristic phenotype of patients with HC caused by a novel cTnT gene mutation, Lys273Glu. Two hundred Japanese probands with HC were screened for mutations in the cTnT gene. The Lys273Glu missense mutation was present in 9 persons from 2 unrelated pedigrees. They exhibited different cardiac morphologies: 1 had a dilated cardiomyopathy-like feature, 7 had left ventricular hypertrophy with normal left ventricular systolic function, and the 6 of them had asymmetric septal hypertrophy. A 1-year-old boy was not evaluated with echocardiography. The mean maximum wall thickness was 18.0 +/- 5.5 mm (range 8 to 24). There were 7 histories of sudden death in 1 of the 2 families. The Lys273Glu substitution in the cTnT gene shows a high degree of penetrance (100% in persons aged >20 years), a high incidence of sudden death, and a partial transition from hypertrophic to dilated cardiomyopathy. Because the location of a mutation appears to influence the development of a phenotype, we suggest that the precise definition of the disease-causing mutation can provide important prognostic information about affected members.     

Airway hyperresponsiveness in transgenic mice overexpressing platelet activating factor receptor is mediated by an atropine-sensitive pathway.

Platelet activating factor (PAF) is a potent mediator potentially involved in the pathogenesis of inflammatory disorders, including bronchial asthma. Recently, transgenic mice overexpressing the PAF receptor (PAFR) gene have been established, and exhibit bronchial hyperresponsiveness, one of the cardinal features of asthma. To elucidate the molecular and pathophysiologic mechanisms underlying PAF-associated bronchial hyperreactivity, we studied airway responsiveness to methacholine (MCh) and serotonin (5-hydroxytryptamine; 5-HT) in PAFR-transgenic mice. In addition, we examined the role of the muscarinic receptor in PAF-induced responses and the binding activities of the muscarinic receptor. The PAFR-transgenic mice exhibited hyperresponsiveness to MCh and PAF; however, no significant differences in 5-HT responsiveness were observed between the control and PAFR-transgenic mice. The administration of atropine significantly blocked PAF-induced responses in PAFR-transgenic mice. There were no differences between the two phenotypes in the binding activities of muscarinic receptor. Morphometric analyses demonstrated that PAFR overexpression did not affect airway structure. These findings suggest that the muscarinic pathway may have a key role in airway hyperresponsiveness associated with PAFR gene overexpression. More generally, PAFR-transgenic mice may provide appropriate models for study of the molecular mechanisms underlying PAF-associated diseases.     

Successful treatment of a young infant who developed high-titer inhibitors against VWF-cleaving protease (ADAMTS-13): important discrimination from Upshaw-Schulman syndrome

We report herein the case of a 9-month-old female infant with acquired thrombotic thrombocytopenic purpura (TTP), which was initially suspected to be either Upshaw-Schulman syndrome (USS or a congenital TTP) or hemolytic uremic syndrome (HUS) because of onset of clinical signs in infancy and accompanying diarrhea. She received combination therapy of plasma exchange, steroid pulse, and high-dose intravenous immunoglobulin infusion that was initiated before the definitive diagnosis, which resulted in excellent clinical improvement. The retrograde analysis of plasma ADAMTS-13 activity and its inhibitor showed a lack of this enzyme activity and the presence of a high-titer IgG inhibitor (200-320 Bethesda units/mL) to this enzyme activity. From our experience, it was suggested that we should recognize the possibility of the patient with acquired TTP in infancy and the importance of plasma exchange therapy for management of its clinical symptoms.     

High-frequency potentials developed in wavelet-transformed electrocardiogram as a novel indicator for detecting Brugada syndrome

BACKGROUND: A reliable alternative method for detecting Brugada syndrome is desirable because the diagnosis of Brugada syndrome using 12-lead ECG is not optimal. OBJECTIVES: The purpose of this study was to assess the usefulness of the wavelet-transformed ECG in detecting Brugada syndrome. METHODS: The study consisted of 15 patients with Brugada syndrome and 15 healthy subjects (control group). The parameters on the signal-averaged ECG and the frequency components recorded from the wavelet-transformed ECG were compared between the two groups. Measurements were repeated after pilsicainide infusion in the two groups of patients, after an isoproterenol infusion following pilsicainide injection, and after administration of cilostazol in the group of patients with Brugada syndrome. RESULTS: The positive rate of late potentials was 80% in the Brugada syndrome group and 0% in the control group (P <.01). The high-frequency components (80-150 Hz) were developed in the Brugada syndrome group to a greater extent than in the control group, but the low-frequency components (10-50 Hz) did not differ (mean peak power at 80 Hz; 713 +/- 36 vs 488 +/- 60, P <.001). After pilsicainide injection, high-frequency components significantly increased in both groups. However, after isoproterenol and cilostazol administration, high-frequency components significantly decreased but remained higher than in the control group (80 Hz; 655 +/- 40 vs 488 +/- 60, P <.001). The sensitivity of the development of high-frequency components in detecting Brugada syndrome was higher than that of signal-averaged ECG (100% vs 80%), but specificity remained high and similar (100% for both methods). CONCLUSION: Abnormally high-frequency components recorded from the wavelet-transformed ECG might be a novel factor in detecting Brugada syndrome.     

SARCOIDOSIS OF THE SPINAL CORD

The authors report a female elderly patient with quadriplegia, hypesthesia below the neck, and rectourinary dysfunction, which were found at autopsy to have been caused by involvement of the lower cervical and upper thoracic segments of the spinal cord in systemic sarcoidosis. Sixty cases of spinal cord sarcoidosis reported in the literature are also reviewed. Most patients had clinical signs which mimicked those of a spinal cord tumor or meningomyelitis. Only in less than one-third of the cases had sarcoidosis been diagnosed before neurological symptoms occurred. Macroscopically, most intramedullary lesions formed a mass, whereas extramedullary lesions usually manifested as meningitis. Histologically, perivascular distribution of sarcoid granulomas was noted in our patient as well as in many cases reported in the literature. The clinical course of the patients with spinal sarcoidosis was usually poor when early diagnosis was not made. ACTA PATHOL. JPN. 35: 1007–1022, 1985.     

Present state and measures of Barrett's cancer in Japan

Barrett's adenocarcinoma is common esophageal cancer in western countries but very rare in Japan. We reviewed 206 cases of Barrett's cancer in Japanese literature that issued from 2000 to 2004. 80% of them were superficial cancer. There was no mucosal Barrett's cancer with lymph nodes metastasis, therefore EMR (endoscopic mucosal resection) method is an appropriate way for mucosal cancer. Barrett's cancer with submucosal invasion occur lymph nodes metastasis, so surgical operation should be applied for deeper invasion to submucosal cancer.     

Detection of hepatocellular carcinoma capsule by contrast-enhanced ultrasound using Levovist: correlations with pathological findings

Purpose To determine the most appropriate therapy for each hepatocellular carcinoma (HCC) nodule, it is important to ascertain whether the tumor has a capsule. The aim of this study was to investigate the diagnostic potential of contrast-enhanced ultrasound (CEUS) in HCC capsule detection by comparing ultrasound findings with histological results from operative specimens. Methods Thirty-six HCC nodules (all smaller than 5 cm) from 36 patients who had undergone hepatectomy were examined by CEUS using Levovist with agent detection imaging. The vascular phase images and time course changes of HCC were observed after a bolus injection of Levovist. We classified the appearance of the tumor artery, tumor enhancement, and washout into several patterns. We grouped HCCs into encapsulated or nonencapsulated on the basis of the histology of the operative specimens, taking into account the effectiveness of transcatheter arterial chemoembolization. Ultrasound and pathological findings were compared to assess the ability of CEUS to detect HCC capsules. Results During the arterial phase, 12 (80.0%) encapsulated and 3 (14.3%) nonencapsulated HCC nodules showed a surrounding artery with branches pattern (P < 0.0001). The sensitivity, specificity, and accuracy of this pattern for HCC capsule detection were 80%, 86%, and 83%, respectively. A branching artery was found in 15 (71.4%) nonencapsulated but in only 3 (20.0%) encapsulated HCC nodules (P < 0.01). The sensitivity, specificity, and accuracy of this branching artery pattern for confirming the absence of a capsule in HCC nodules were 71%, 80%, and 75%, respectively. Almost all HCC nodules showed strong–moderate or weak enhancement and strong–moderate or mild washout. Neither enhancement nor washout pattern correlated with the presence of a capsule. Conclusion The arterial phase of CEUS is very useful for detection of HCC capsules and therefore facilitates selection of the most appropriate treatment method for HCC.     

alpha1-Adrenergic receptor antagonists induce production of IL-18 and expression of ICAM-1 and CD40 in human monocytes

The activation of T cells plays a role in antitumor response. Monocytes activate T cells by inducing the cell-to-cell interaction that involves the engagement of adhesion molecules with their ligands, and the production of IL-18. The authors examined the effect of the quinazoline-based alpha1-adrenergic receptor antagonists bunazosin, doxazosin, prazosin, and terazosin on the expression of adhesion molecules such as ICAM-1, B7.1, B7.2, CD40, and CD40L on monocytes isolated from human peripheral blood mononuclear cells. Doxazosin, prazosin, and terazosin induced the expression of ICAM-1 and CD40 but had no effect on the expression of B7.1, B7.2, and CD40L. Moreover, IL-18 was detected in the medium of incubated monocytes treated with doxazosin, prazosin, and terazosin. Bunazosin did not affect adhesion molecule expression and IL-18 production, suggesting that the chemical structure of quinazoline might not be related to the effect of doxazosin, prazosin, and terazosin. Although caspase-1 inhibitor completely abolished the production of IL-18, anti-IL-18 mAb and caspase-1 inhibitor partially inhibited the increase in ICAM-1 and CD40 expression induced by doxazosin, prazosin, and terazosin. Doxazosin, prazosin, and terazosin can induce monocyte activation with a specific pattern of expression of adhesion molecules and IL-18 production, and this may lead to T-cell activation through the cell-to-cell interaction. The activation of T cells induced by the increase of the expression of ICAM-1 and CD40 and the production of IL-18 may be involved in the anti-cancer effects of doxazosin, prazosin, and terazosin.     

Increased expression of TRAIL receptor 3 on eosinophils in Churg‐Strauss syndrome

Objective

Prolonged survival of eosinophils plays an important role in the pathogenesis of Churg‐Strauss syndrome (CSS); however, its detailed molecular mechanism is still unclear. TRAIL and its receptors are expressed on a variety of cells, including eosinophils. In this study, we examined the expression of TRAIL receptors on eosinophils from patients with CSS.

Methods

TRAIL receptor expression was assessed on eosinophils from healthy volunteers, patients with CSS, patients with asthma, and patients with hypereosinophilia due to parasitic infection. TRAIL‐induced apoptosis of eosinophils was compared between the patients with CSS and patients with asthma. RNA interference was used to assess the effects of suppression of TRAIL receptor 3.

Results

Expression of TRAIL receptor 3, a decoy receptor that acts as an antiapoptotic receptor, on eosinophils from patients with CSS was significantly higher than that in the other subjects. Moreover, in CSS, serum TRAIL receptor 3 levels showed a significant positive correlation with peripheral eosinophil counts, tissue‐infiltrating eosinophils stained positive for this receptor, and peripheral T cells expressed TRAIL on their surface. Compared with asthma patients, eosinophils from CSS patients showed a significantly lower percentage of recombinant TRAIL, less autologous T cell–induced apoptosis, and decreased level of active caspase 3. Suppression of TRAIL receptor 3 through RNA interference significantly increased the recombinant TRAIL–induced apoptosis of eosinophils from CSS patients.

Conclusion

Increased expression of TRAIL receptor 3 on eosinophils from patients with CSS was observed. These alterations in TRAIL receptor 3 expression might be involved in the molecular pathogenesis of CSS eosinophilia.