Interrelation of the stagnant slab, Ontong Java Plateau, and intraplate volcanism as inferred from seismic tomography.

We investigated the seismological structure beneath the equatorial Melanesian region, where is tectonically unique because an immense oceanic plateau, a volcanic chain and subduction zones meet. We conducted a multi-frequency P-wave tomography using data collected from an approximately 2-year-long seismic experiment around the Ontong Java Plateau (OJP). High-velocity anomalies were revealed beneath the center of the OJP at a depth of ~ 150 km, the middle-eastern edge of the OJP at depths of 200-300 km, and in the mantle transition zone beneath and around the OJP; low-velocity anomalies were observed along the Caroline volcanic island chain above 450 km depth. These anomalies are considered to be associated with the thick lithosphere of the OJP, remnant dipping Pacific slab, stagnant Pacific slab, and a sheet-like upwelling. The broad stagnant slab was formed due to rapid trench retreat from 48 to 25 Ma until when the OJP with thick lithosphere collided with a subduction boundary of the Pacific and Australian plates. This collision triggered slab breakoff beneath the arc where the dipping slab remained. The stagnant Pacific slab in the mantle transition zone restricted the plume upwelling from the lower mantle causing sheet-like deformed upwelling in the upper mantle.

[MBL quality control survey of autoantibodies--25 years of activity and its achievement--mainly antinuclear antibodies].

Annual MBL Quality Control Survey of Autoantibodies has continued to this day since it started in 1983 as the only quality control survey of autoantibodies in Japan. The survey has aimed at unification and standardization of measurement value, as well as finding out between-laboratory differences in results through reporting the results of tabulation to the participating laboratories. For carrying out the survey, we intend to make our efforts to promote assurance and standardization of the quality control of the autoantibodies. The number of participant on this survey has been increasing every year and more than 500 laboratories participate not only in Japan but also from Asia and European countries. The laboratories that participated in this survey are the ones that usually perform ANA test, anti-DNA antibodies test, anti-ENA antibodies test, AMA test, ASMA test, anti-cardiolipin antibodies test and anti-CCP antibodies test. The purpose of the survey is to standardize antinuclear antibodies testing value in semi quantitative assay using ANA control serum or our titer control HEPASERA-1. We got 12% increase from 79% to 91% in 1986 using ANA control serum. Additionally, we reached 97% (86% to 97%) of convergence in 2001 by using HEPASERA-1, which contains 4 major pattern titer controls from 1993. In 2007, coefficient of variation (CV) for anti-dsDNA antibodies was 13%, showing better result than 25% of the first survey in 1993. We started secondary survey for laboratories which reported a result far apart. In the secondary survey, we made investigation for cause and improvement action. We conclude quality control survey is useful for autoantibodies testing for its result convergence.

Augmentation of pulmonary vein backflow velocity during left atrial contraction: a novel phenomenon responsible for progression of atrial fibrillation in hypertensive patients.

BACKGROUND: Atrial fibrillation (AF) is a common arrhythmia showing disease progression. However, echocardiographic prediction of such progression remains incomplete. This study aimed to identify echocardiographic predictors of AF progression in hypertensive patients. METHODS: Hypertensive patients with paroxysmal AF were divided into two groups: patients with AF which became permanent (group A; n = 13) and those with AF which remained paroxysmal (group B; n = 46) during the same follow-up period (8.0 +/- 2.4 years). Clinical baselines showed no significant differences except for age. Transthoracic echocardiography was recorded 1-2 weeks after termination of the first-detected paroxysms of AF. RESULTS: Echocardiography showed greater left atrial (LA) dimension (p = 0.023) and late diastolic pulmonary vein (PV) backflow velocity (p < 0.001), and a lower LA fractional shortening (p = 0.008) in group A than in group B. Multilogistic regression analysis demonstrated that augmented PV backflow (p = 0.007) and reduced LA fractional shortening (p = 0.032) were independent predictors of the progression of AF. The receiver-operating characteristic curve demonstrated that PV backflow augmentation is the best predictor of future AF perpetuation. CONCLUSION: PV backflow leading to cyclic stretching of PV musculature contributes to AF progression.

Structure of the tsunamigenic plate boundary and low-frequency earthquakes in the southern Ryukyu Trench.

It has been recognized that even weakly coupled subduction zones may cause large interplate earthquakes leading to destructive tsunamis. The Ryukyu Trench is one of the best fields to study this phenomenon, since various slow earthquakes and tsunamis have occurred; yet the fault structure and seismic activity there are poorly constrained. Here we present seismological evidence from marine observation for megathrust faults and low-frequency earthquakes (LFEs). On the basis of passive observation we find LFEs occur at 15-18 km depths along the plate interface and their distribution seems to bridge the gap between the shallow tsunamigenic zone and the deep slow slip region. This suggests that the southern Ryukyu Trench is dominated by slow earthquakes at any depths and lacks a typical locked zone. The plate interface is overlaid by a low-velocity wedge and is accompanied by polarity reversals of seismic reflections, indicating fluids exist at various depths along the plate interface.

[Autoantibodies].

The autoantibody test gives significant information for diagnosis of autoimmune diseases. Since the finding of the LE-cell in 1948, dozens of autoantibodies have been found. Anti nuclear antibody (ANA) is the essential test for the screening of autoantibodies. Indirect immunofluorescence (IIF) is the conventional method for the detection of ANA. IIF can detect a wide spectrum of ANA and gives abundant information obtained from a staining pattern. However under the recent circumstances of using advanced fluorescent microscopes and reagents we often have difficulty interpreting positive results seen in normal individuals and in detailed staining patterns. ELISA (enzyme-linked immunosorbent assay), detecting disease specific autoantibodies alone, is one solution. Some antibodies such as anti-DNA or anti-ENA (extractable nuclear antigen) have a strong relation to specific diseases. These autoantibodies have been detected by IIF, RIA (radioimmunoassay) or DID (double immune diffusion). With the progress of molecular biology many autoantigens have been characterized. Now ELISA is a typical way to detect autoantibodies because purified or recombinant antigens are easily available. Though RF (rheumatoid factor) is the historical autoantibody detected in RA patients, the specificity to RA is low. The new anti-CCP is promising from its high specificity and sensitivity. Now we can choose various kind of autoantibody tests, not only conventional ones but also newly developed ones. For diagnosis and treatment of autoimmune diseases, understanding of both clinical significance and methodology is important.

Significance of dermoscopic patterns in detecting malignant melanoma on acral volar skin: results of a multicenter study in Japan.

OBJECTIVE: To determine diagnostic variables such as sensitivity and specificity of the major dermoscopic patterns observed in melanocytic lesions on acral volar skin, with particular attention to the significance of the parallel ridge pattern and irregular diffuse pigmentation in detecting acral melanoma. DESIGN: Multicenter, retrospective study. SETTING: University hospitals in Japan. PATIENTS: Patients with melanocytic lesions on acral volar skin. A total of 712 melanocytic lesions (103 malignant melanomas, including 36 in situ lesions, and 609 melanocytic nevi) were consecutively collected from the files of 3 hospitals. Diagnoses of all the lesions had been determined histopathologically. INTERVENTIONS: Dermoscopic examination. MAIN OUTCOME MEASURES: The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of the major dermoscopic patterns seen in benign and malignant melanocytic lesions on acral volar skin. RESULTS: The parallel ridge pattern and irregular diffuse pigmentation showed extremely high specificity (99.0% and 96.6%, respectively) and very high negative predictive value (97.7% and 97.5%, respectively) in malignant melanoma. For melanoma in situ, the positive predictive value and diagnostic accuracy of the parallel ridge pattern were significantly higher than those of irregular diffuse pigmentation (P = .009 and P = .006, respectively). In melanocytic nevi, the specificity and positive predictive value of the parallel furrow pattern and/or the latticelike pattern were found to be very high (93.2% and 98.3%, respectively). CONCLUSIONS: Dermoscopy is immensely helpful in differentiating malignant melanomas from melanocytic nevi on acral volar skin. Moreover, the parallel ridge pattern aids in detecting acral melanomas in early, curable stages.

Early acral melanoma in situ: correlation between the parallel ridge pattern on dermoscopy and microscopic features.

In non-white populations, acral skin is the most prevalent site of malignant melanoma. Early melanomas of this anatomic site are often misdiagnosed as melanocytic nevi, which are not uncommon on acral skin. In fact, clinical and/or histopathological features of melanocytic nevi occasionally mimic those of early acral melanoma and vice versa, and thus differentiation of early acral melanoma from melanocytic nevus is sometimes very difficult for clinicians as well as for histopathologists. Our dermoscopic investigation has revealed that the parallel ridge pattern, a band-like pigmentation on the ridges of the skin markings, is highly specific to malignant melanoma in situ on acral volar skin. In the present study, we reviewed 22 acral melanocytic lesions that showed the parallel ridge pattern on dermoscopy but had very subtle clinical and/or histopathological presentations. We diagnosed 20 of them as early melanoma in situ by careful histopathological examination, which revealed histopathological features very similar to those seen in macular portions of overt acral melanoma, but fundamentally different from features found in melanocytic nevi on acral skin. In correspondence with their dermoscopic pattern, in these early lesions of acral melanomas, proliferation of solitary arranged melanocytes was mainly detected in the crista profunda intermedia, the epidermal rete ridge underlying the ridge of the skin marking. The two remaining lesions were diagnosed as possible cases of acquired melanocytic nevus because of the formation of well-demarcated nests of melanocytes in the epidermal rete ridges. We propose that a finding of preferential proliferation of solitary arranged melanocytes in the crista profunda intermedia is an important clue for the histopathological diagnosis of early phases of acral melanoma.