Potentiation of the ligand-binding activity of integrin alpha3beta1 via association with tetraspanin CD151

CD151, one of the tetraspanins, forms a stable complex with integrin alpha3beta1, the major laminin receptor on the cell surface. We found that 8C3, an anti-CD151 mAb obtained by screening for reactivity with integrin alpha3beta1-CD151 complexes, was capable of dissociating CD151 from integrin alpha3beta1, thereby allowing us to deplete CD151 from purified integrin alpha3beta1-CD151 complexes. The CD151-free integrin alpha3beta1 thus obtained showed a significant reduction in its ability to bind to laminin-10/11, a high-affinity ligand for integrin alpha3beta1, with a concomitant reduction in its reactivity with mAb AG89, which recognizes activated beta1-containing integrins. These results raised the possibility that the association of integrin alpha3beta1 with CD151 potentiates the ligand-binding activity of the integrin through sustaining its activated conformation. In support of this possibility, the ligand-binding activity was restored when CD151-free integrin alpha3beta1 was reassociated with purified CD151. 8C3-induced dissociation of CD151 from integrin alpha3beta1 was also demonstrated on the surface of living cells by fluorescent resonance energy transfer imaging, accompanied by a concomitant reduction in the cell adhesion to laminin-10/11-coated substrates. CD151 knock-down by RNA interference also resulted in a reduction in the adhesive activity of the cells. Taken together, these results indicate that CD151 association modulates the ligand-binding activity of integrin alpha3beta1 through stabilizing its activated conformation not only with purified proteins but also in a physiological context.     

Electrocardiographic characteristics of the variants of idiopathic left ventricular outflow tract ventricular tachyarrhythmias

Background: Despite similar QRS morphology, idiopathic repetitive monomorphic ventricular tachyarrhythmias (VTs) of left ventricular outflow tract (LVOT) are known to have the variants of different adjacent origins, including the aorto-mitral continuity (AMC), anterior site around the mitral annulus (MA), aortic sinus cusps (ASC), and epicardium. However, the electrocardiographic characteristics of those variants previously have not been evaluated fully.
Methods and Results: Based on the mapping site and successful ablation in 45 consecutive patients with LVOT-VTs, we classified them into VTs of AMC (n = 3), MA (n = 8), ASC (n = 32), and epicardial (n = 2) origins. In all patients, we performed activation mapping and an electrocardiographic analysis. All AMC-VTs patients had monophasic R waves in almost all the precordial leads, while those with anterior MA-VTs had an Rs pattern in some precordial leads except for lead V6, and those with ASC-VTs had a variable transitional zone in leads V1–4. There was no S wave in lead V6 in any group except for one patient with anterior MA-VTs. The intrinsicoid deflection time in the AMC-VTs patients and anterior MA-VTs patients was significantly greater than in those with ASC-VTs (P < 0.05). There was no significant difference in the R-wave amplitude in the inferior leads among the groups. Successful radiofrequency catheter ablation (RFCA) was achieved in all patients except for in those with epicardial origin VT.
Conclusions: Despite many morphological similarities, the LVOT-VTs originating from the AMC, anterior MA and ASC could be identified by our proposed electrocardiographic characteristics in order to safely perform RFCA.     

The usefulness of the consensus clinical diagnostic criteria in Brugada syndrome

Background

Consensus statements were proposed for the diagnosis of Brugada syndrome (BS). The clinical diagnostic criteria were defined as documented ventricular fibrillation or ventricular tachycardia (VT), family history of sudden cardiac death at < 45 years, diagnostic ECGs of family members, inducibility of VT during electrophysiological study, syncope or nocturnal agonal respiration. The clinical validation of these criteria is still missing.Methods and results280 patients (41 ± 18 years, male: 168 pts) with diagnostic coved type I ECG were included. Consensus clinical diagnostic criteria were present in 244 (87%) patients (40 ± 18 y, 142 males). In 36 pts (13% of the 280 pts, 51 ± 12 years, 27 males) consensus clinical diagnostic criteria were not met. Nine patients (25%) presented with spontaneous type I ECG. Ten of the 36 patients (28%) had a history of atrial fibrillation and 13 (36%) had conduction disease on the baseline ECG. In 23 patients (64%) family screening was not performed. Two of the 36 patients had undocumented syncope during follow-up. Univariate analysis showed no significant difference in event free survival between patients with or without consensus clinical diagnostic criteria.

Conclusions

In a significant number of patients with diagnostic ECG pattern the current diagnostic criteria for BS are not met. These patients have frequently spontaneous type I ECG and clinical signs of Brugada syndrome as paroxysmal atrial fibrillation or conduction disturbances. Our results suggest that in patients with a diagnostic type I ECG pattern the current clinical consensus diagnostic criteria have limited added diagnostic value.     

Impaired regulation of serum hepcidin during phlebotomy in patients with chronic hepatitis C

Aim: This study was conducted to determine the clinical relevance of hepcidin, a recently identified key iron regulatory hormone, in patients with chronic hepatitis C virus (C‐HCV). Methods: Serum hepcidin levels were measured in 9 C‐HCV patients by surface‐enhanced laser desorption/ionization time of flight mass spectrometry (SELDI‐TOF‐MS), and compared to those of healthy controls. Sequential changes of hepcidin were also investigated during phlebotomy. Results: Serum hepcidin and ferritin were significantly higher in C‐HCV than in controls (P = 0.0002), these two variables were strongly related to each other (r = 0.658; P < 0.01), and phlebotomy significantly decreased serum hepcidin in C‐HCV (P = 0.0007); all these results recollect the hepcidin response to iron signal. Hepcidin/ferritin ratio, an index of the appropriateness of hepcidin expression relative to iron overload, was significantly lower in C‐HCV than in controls (0.33 ± 0.41 vs. 0.73 ± 0.36, P = 0.0068). This relative impairment of hepcidin expression was not reversible after phlebotomy (P = NS). Conclusions: Although the hepcidin expression responds to iron conditions in C‐HCV, this response is relatively limited. This relative impairment of hepcidin expression may be relevant to disease progression, and thus correction of its regulation may be beneficial for these iron‐overloaded C‐HCV patients.     

The risk of lymph node metastasis in mucosal gastric carcinoma: especially for a mixture of differentiated and undifferentiated adenocarcinoma

Background/Aims: Endoscopic submucosal dissection (ESD) is gaining wider acceptance for the treatment of early gastric carcinoma (EGC) and its indication has been extended to mucosal gastric carcinoma with undifferentiated component in some institutes. Our aims were to confirm the frequency of lymph node metastasis in such cases and clarify the demarcation in indications for ESD. Methodology: We evaluated medical data of 287 patients with mucosal gastric carcinoma who underwent surgical resection between 1996 and 2008. The tumours were histologically classified into purely differentiated (PD), differentiatedpredominant mixed (DPM), undifferentiated-predominant mixed (UPM) and purely undifferentiated (PU) types. Results: Lymph node metastasis was identified in seven (2.4%) of the 287 patients and was detected more frequently in UPM (10%, two of 20) and PU (4%, four of 98), compared with PD (none of 148) (p=0.01 and 0.02, respectively). In mixed-type carcinoma, size was a significant risk factor for lymph node metastasis (p=0.04). Conclusions: It might be better to select gastrectomy rather than ESD for the treatment of mucosal gastric carcinoma with an undifferentiated component.     

Ectopic hamartomatous thymoma growing in the sternocleidomastoid muscle masquerading as sarcoma.

The distinction between ectopic hamartomatous thymoma and sarcoma is difficult, and preoperative biopsy and intraoperative histopathological examination fail to give a definitive diagnosis. It is important to recognise ectopic hamartomatous thymoma as one of the differential diagnoses of a cervical tumour.     

Unidentified virus-like particles are detected in plasmas with elevated ALT levels: are they significant of etiological agent(s) of non-B,non-C hepatitis?

GB virus C (GBV-C) and hepatitis G virus (HGV) have been proposed as new viruses etiologically implicated in non-B, non-C hepatitis, but the morphology of these particular virus particles is still unknown, and most cases of non-A to E hepatitis do not relate to their infections. We tried to visualize virus-like particles (VLPs) in plasma samples from hepatitis B surface antigen- and antibody to hepatitis C virus (HCV)-negative blood donors with elevated alanine aminotransferase (ALT), and examined the association of the virus-like particles and the genomes of parenterally transmissible GBV-C/HGV. Twenty-three plasma samples, 13 with elevated ALT levels and 10 with normal ALT values, from blood donors without infections of hepatitis B virus (HBV) and HCV, were subjected to a 20%–60% sucrose density gradient centrifugation, and virus-like particles were observed by electron microscopy. GBV-C/HGV RNAs in the plasmas were tested. Virus-like particles were found in the fractions with densities of 1.15–1.16 g/ml from 12 of 13 (92.3%) plasmas with elevated ALT levels and 1 of 10 (10%) normal controls. The ultrastructural morphology of visualized VLPs was pleomorphic in size and appearance; the majority of the VLPs were 50- to 80-nm spherical particles with a 35- to 45-nm inner core and 9- to 12-nm-long surface spikelike projections. Rodlike VLPs 50–70 nm in diameter with a length of 110–160 nm were also observed in the same samples. The incidence of detection of the circulating VLPs was significantly (P < 0.001) related to elevated ALT levels, but GBV-C/HGV RNAs were detected in none of the plasmas containing the virus-like particles. Spherical VLPs are detected in HBV- and HCV-negative plasmas significantly correlated with the elevation of ALT, suggesting that they are implicated in non-B, non-C hepatitis.