Search

Possible local influence of an extreme marine heatwave is investigated on unprecedentedly hot summer around northern Japan in 2023. Sea-surface temperatures (SSTs) and subsurface ocean temperatures around northern Japan were also unprecedentedly high in the summer. This was especially the case off the east coast of Japan, where cool Oyashio water was replaced with much warmer water due to a striking poleward meander of the Kuroshio Extension persistent from the spring. Particularly amplified near-surface air temperature anomalies and even stronger warm anomalies in the subsurface ocean suggest that the marine heatwave acted to sustain the atmospheric heatwave. Anomalous upward of latent and sensible heat fluxes from the warmed sea surface are indicative of local oceanic impact. The warm SST anomalies reduced the lower-tropospheric stratification to maintain unfavourable condition for low-level cloud formation, which in turn led to increased surface insolation for further SST warming as positive feedback. The increased moisture in the warmed lower troposphere contributed to the enhanced surface downward longwave radiation. This enhanced greenhouse effect acted not only as positive feedback on the warm SST anomalies that increased evaporation but also as a contributor for the extreme warmth over northern Japan landmass. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various reports within the issue on topics including a thorough description of oceanic fronts in the western North Pacific, East Asia marginal seas and coastal seas around Japan, climatological statistics of oceanic rings detached from KE jet, and trends observed in surface and subsurface temperature around the Antarctic Circumpolar Current and associated frontal zones.

The baiu and Kuroshio Extension (KE) fronts, both zonally oriented and nearly collocated east of Japan, are the dominant summertime features of the atmosphere and ocean, respectively, over the midlatitude northwest Pacific. An atmospheric sounding campaign was conducted on board the R/V Roger Revelle during the 2005 summer. Transects of soundings across the KE front are analyzed to study its effects on the atmosphere, along with continuous surface meteorological and ceilometer cloud-base observations. While the KE front remained nearly stationary during the cruise, the baiu front displayed large meridional displacements that changed wind direction across the KE front. The presence of sharp sea surface temperature (SST) gradients anchored by the KE enhanced the thermal and moisture advection, causing substantial changes in the marine atmospheric boundary layer (MABL) structure. When the baiu front was displaced north of the KE front, southwesterly winds advected warm, humid air from the subtropics over the cold water, producing a surface inversion favorable to fog formation. When the baiu front was to the south, on the other hand, northerly winds across the KE front destabilized the MABL, leading to the formation of a solid low-cloud deck beneath a strong capping inversion. The wind changes with the meridional displacement of the baiu front thus caused large variations in near-surface atmospheric stability and surface turbulent heat fluxes, with potential feedback on deep convection and fog/low-cloud formation around the front. [ABSTRACT FROM AUTHOR]

Through analysis of a hindcast integration of an eddy-resolving quasi-global ocean general circulation model, decadal variability in the Kuroshio–Oyashio Extension region is investigated, with particular emphasis on that of the subarctic (Oyashio) and the Kuroshio Extension (KE) fronts. The KE front is deep and is accompanied by a sharp sea surface height (SSH) gradient with modest sea surface temperature (SST) gradient. In contrast, the subarctic front is shallow and is recognized as a zone of tight gradient in SST but not SSH. As a decadal-scale change from a warm period around 1970 to a cool period in the mid-1980s, those fronts in the model migrate southward as observed, and the associated pronounced cooling is confined mainly to those frontal zones. Reflecting the distinctive vertical structure of the fronts, the mixed layer cooling is the strongest along the subarctic front, whereas the subsurface cooling and the associated salinity changes are most pronounced along the KE front. Concomitantly with their southward migration, the two fronts have undergone decadal-scale intensification. Associated with reduced heat release into the atmosphere, the cooling in the frontal zones can be attributed neither to the direct atmospheric thermal forcing nor to the advective effect of the intensified KE, while the advective effect by the intense Oyashio can contribute to the cooling in the subarctic frontal zone. In fact, their time evolution is not found to be completely coherent, suggesting that their variability may be governed by different mechanisms. Decadal SSH variability in the KE frontal zone seems to be largely explained by propagation of baroclinic Rossby waves forced by anomalous Ekman pumping in the central North Pacific. This process alone cannot fully explain the corresponding variability in the subarctic frontal zone, where eastward propagating SSH anomalies off the Japanese coast seem to be superimposed on the Rossby wave signals. [ABSTRACT FROM AUTHOR]

Background: This is the first report from a multicenter prospective cohort study of colorectal neuroendocrine tumor (NET), the C-NET STUDY, conducted to assess the long-term outcomes of the enrolled patients. This report aimed to elucidate the clinicopathological features of the enrolled patients and lesions., Methods: Colorectal NET patients aged 20-74 years were consecutively enrolled and followed up at 50 institutions. The baseline characteristics and clinicopathological findings at enrollment and treatment were assessed., Results: A total of 495 patients with 500 colorectal NETs were included. The median patient age was 54 years, and 85.3% were asymptomatic. The most frequent lesion location was the lower rectum (88.0%); 99.4% of the lesions were clinically diagnosed to be devoid of metastatic findings, and 95.4% were treated with endoscopic resection. Lesions < 10 mm comprised 87.0% of the total, 96.6% had not invaded the muscularis propria, and 92.6% were classified as WHO NET grade 1. Positive lymphovascular involvement was found in 29.2% of the lesions. Its prevalence was high even in small NETs with immunohistochemical/special staining for pathological assessment (26.4% and 40.9% in lesions sized < 5 mm and 5-9 mm, respectively). Among 70 patients who underwent radical surgery primarily or secondarily, 18 showed positive lymph node metastasis., Conclusions: The characteristics of real-world colorectal NET patients and lesions are elucidated. The high positivity of lymphovascular involvement in small NETs highlights the necessity of assessing the clinical significance of positive lymphovascular involvement based on long-term outcomes, which will be examined in later stages of the C-NET STUDY., Trial Registration Number: UMIN000025215., (© 2022. Japanese Society of Gastroenterology.)

Background and Aim: The Japan narrow-band imaging (NBI) Expert Team (JNET) was organized to unify four previous magnifying NBI classifications (the Sano, Hiroshima, Showa, and Jikei classifications). The JNET working group created criteria (referred to as the NBI scale) for evaluation of vessel pattern (VP) and surface pattern (SP). We conducted a multicenter validation study of the NBI scale to develop the JNET classification of colorectal lesions., Methods: Twenty-five expert JNET colonoscopists read 100 still NBI images with and without magnification on the web to evaluate the NBI findings and necessity of the each criterion for the final diagnosis., Results: Surface pattern in magnifying NBI images was necessary for diagnosis of polyps in more than 60% of cases, whereas VP was required in around 90%. Univariate/multivariate analysis of candidate findings in the NBI scale identified three for type 2B (variable caliber of vessels, irregular distribution of vessels, and irregular or obscure surface pattern), and three for type 3 (loose vessel area, interruption of thick vessel, and amorphous areas of surface pattern). Evaluation of the diagnostic performance for these three findings in combination showed that the sensitivity for types 2B and 3 was highest (44.9% and 54.7%, respectively), and that the specificity for type 3 was acceptable (97.4%) when any one of the three findings was evident. We found that the macroscopic type (polypoid or non-polypoid) had a minor influence on the key diagnostic performance for types 2B and 3., Conclusion: Based on the present data, we reached a consensus for developing the JNET classification., (© 2018 Japan Gastroenterological Endoscopy Society.)

Objectives: Conventional endoscopic resection (CER) is a widely accepted treatment for early colorectal neoplasia; however, large colorectal neoplasias remain problematic, as they necessitate piecemeal resection, increasing the risk of local recurrence. Endoscopic submucosal dissection (ESD) can improve the en bloc resection rate. This study aimed to evaluate local recurrence and its associated risk factors after endoscopic resection (ER) for colorectal neoplasias ≥20 mm., Methods: A multicenter prospective study at 18 medium- and high-volume specialized institutions was conducted in Japan. Follow-up colonoscopy was performed after 12 months in cases of complete resection and after 3-6 months in cases of incomplete resection. Local recurrence was confirmed by endoscopic findings and/or pathological analysis., Results: Follow-up colonoscopy was performed in 1,524 of 1,845 enrolled colorectal neoplasias (mean age, 65 years; 885 men; median tumor size, 32.8 mm). The local recurrence rates were 4.3% (65/1,524), 6.8% (55/808), and 1.4% (10/716) for the entire cohort, for CER, and for ESD, respectively. The relative risks of local recurrence were 0.21 (95% confidence interval, 0.11-0.39) with ESD compared with CER, 0.32 (95% confidence interval, 0.11-0.92) with en bloc ESD compared with en bloc CER, and 0.90 (95% confidence interval, 0.39-2.12) with piecemeal ESD compared with piecemeal CER. Significant factors associated with local recurrence were piecemeal resection, laterally spreading tumors of granular type, tumor size ≥40 mm, no pre-treatment magnification, and ≤10 years of experience in CER, and piecemeal resection only in ESD., Conclusions: En bloc ESD reduces the local recurrence rate for large colorectal neoplasias. Piecemeal resection is the most important risk factor for local recurrence regardless of the ER method used.

We carried out a retrospective questionnaire survey of 792 submucosal colorectal carcinoma (CRC) cases from 15 institutions affiliated with the Colorectal Endoscopic Resection Standardization Implementation Working Group in Japanese Society for Cancer of the Colon and Rectum. In these cases, endoscopic resection (ER) and surveillance was carried out without additional surgical resection. Local recurrence or metastasis was observed in 18 cases. Local submucosal recurrence was observed in 11 cases, and metastatic recurrence was observed in 13 cases. Among the 15 cases in which the depth of submucosal invasion was measured, two cases showed depth less than 1000 µm, which has other risk factors for metastasis. Metastatic recurrence was observed in the lung, liver, lymph node, bone, adrenal glands, and the brain; in some cases, metastatic recurrence was observed in multiple organs. Death due to primary disease was observed in six cases. The average interval between ER and recurrence was 19.7 ± 9.2 months. In 16 cases, recurrence was observed within 3 years after ER. Thus, validity of ER without additional surgical resection for cases with the conditions that the depth of submucosal invasion is less than 1000 µm and the histological grade is well or moderately differentiated adenocarcinoma with no lymphatic and venous involvement was proven., (© 2011 The Authors. Digestive Endoscopy © 2011 Japan Gastroenterological Endoscopy Society.)

Bleeding, perforation, and residual/local recurrence are the main complications associated with colonoscopic treatment of colorectal tumor. However, current status regarding the average incidence of these complications in Japan is not available. We conducted a questionnaire survey, prepared by the Colorectal Endoscopic Resection Standardization Implementation Working Group, Japanese Society for Cancer of the Colon and Rectum (JSCCR), to clarify the incidence of postoperative bleeding, perforation, and residual/local recurrence associated with colonoscopic treatment. The total incidence of postoperative bleeding was 1.2% and the incidence was 0.26% with hot biopsy, 1.3% with polypectomy, 1.4% with endoscopic mucosal resection (EMR), and 1.7% with endoscopic submucosal dissection (ESD). The total incidence of perforation was 0.74% (0.01% with the hot biopsy, 0.17% with polypectomy, 0.91% with EMR, and 3.3% with ESD). The total incidence of residual/local recurrence was 0.73% (0.007% with hot biopsy, 0.34% with polypectomy, 1.4% with EMR, and 2.3% with ESD). Colonoscopic examination was used as a surveillance method for detecting residual/local recurrence in all hospitals. The surveillance period differed among the hospitals; however, most of the hospitals reported a surveillance period of 3-6 months with mainly transabdominal ultrasonography and computed tomography in combination with the colonoscopic examination., (© 2010 The Authors. Digestive Endoscopy © 2010 Japan Gastroenterological Endoscopy Society.)