Machine learning application for classification of Alzheimer's disease stages using 18F-flortaucipir positron emission tomography.

BACKGROUND: The progression of Alzheimer's dementia (AD) can be classified into three stages: cognitive unimpairment (CU), mild cognitive impairment (MCI), and AD. The purpose of this study was to implement a machine learning (ML) framework for AD stage classification using the standard uptake value ratio (SUVR) extracted from 18F-flortaucipir positron emission tomography (PET) images. We demonstrate the utility of tau SUVR for AD stage classification. We used clinical variables (age, sex, education, mini-mental state examination scores) and SUVR extracted from PET images scanned at baseline. Four types of ML frameworks, such as logistic regression, support vector machine (SVM), extreme gradient boosting, and multilayer perceptron (MLP), were used and explained by Shapley Additive Explanations (SHAP) to classify the AD stage. RESULTS: Of a total of 199 participants, 74, 69, and 56 patients were in the CU, MCI, and AD groups, respectively; their mean age was 71.5 years, and 106 (53.3%) were men. In the classification between CU and AD, the effect of clinical and tau SUVR was high in all classification tasks and all models had a mean area under the receiver operating characteristic curve (AUC) > 0.96. In the classification between MCI and AD, the independent effect of tau SUVR in SVM had an AUC of 0.88 (p < 0.05), which was the highest compared to other models. In the classification between MCI and CU, the AUC of each classification model was higher with tau SUVR variables than with clinical variables independently, which yielded an AUC of 0.75(p < 0.05) in MLP, which was the highest. As an explanation by SHAP for the classification between MCI and CU, and AD and CU, the amygdala and entorhinal cortex greatly affected the classification results. In the classification between MCI and AD, the para-hippocampal and temporal cortex affected model performance. Especially entorhinal cortex and amygdala showed a higher effect on model performance than all clinical variables in the classification between MCI and CU. CONCLUSIONS: The independent effect of tau deposition indicates that it is an effective biomarker in classifying CU and MCI into clinical stages using MLP. It is also very effective in classifying AD stages using SVM with clinical information that can be easily obtained at clinical screening.

Curcumin Ameliorates Particulate Matter-Induced Pulmonary Injury through Bimodal Regulation of Macrophage Inflammation via NF-κB and Nrf2.

The direct effects of particulate matter (PM) on lung injury and its specific molecular mechanisms are unclear. However, experimental evidence has shown that oxidative stress-mediated inflammation in macrophages is the main pathological outcome of PM exposure. Curcumin has been reported to protect organs against the disturbance of homeostasis caused by various toxic agents through anti-inflammatory and antioxidative effects. However, the protective action of curcumin against PM-induced pulmonary inflammation and the underlying mechanism have not been thoroughly investigated. In this study, we established a PM-induced pulmonary inflammation mouse model using the intratracheal instillation method to investigate the protective ability of curcumin against PM-induced pulmonary inflammation. Compared to the mice treated with PM only, the curcumin-treated mice showed alleviated alveolar damage, decreased immune cell infiltration, and reduced proinflammatory cytokine production in both lung tissue and BALF. To evaluate the underlying mechanism, the mouse macrophage cell line RAW264.7 was used. Pretreatment with curcumin prevented the production of PM-induced proinflammatory cytokines by deactivating NF-κB through the suppression of MAPK signaling pathways. Furthermore, curcumin appears to attenuate PM-induced oxidative stress through the activation of Nrf2 and downstream antioxidant signaling. Our findings demonstrate that curcumin protects against PM-induced lung injury by suppressing oxidative stress and inflammatory activation in macrophages.

Impact of the COVID-19 Pandemic on Emergency Department Workload and Emergency Care Workers' Psychosocial Stress in the Outbreak Area.

Background and Objectives: Due to the unexpected spread of coronavirus disease 2019 (COVID-19), there was a serious crisis of emergency medical system collapse. Healthcare workers working in the emergency department were faced with psychosocial stress and workload changes. Materials and Methods: This was a cross-sectional survey of healthcare workers in the emergency department in Daegu and Gyeongbuk, Korea, from November 16 to 25, 2020. In the survey, we assessed the general characteristics of the respondents; changes in the working conditions before and after the COVID-19 pandemic; and resulting post-traumatic stress disorder, depression and anxiety statuses using 49 questions. Results: A total of 529 responses were collected, and 520 responses were included for the final analyses. Changes in working conditions and other factors due to COVID-19 varied by emergency department level, region and disease group. Working hours, intensity, role changes, depression and anxiety scores were higher in the higher level emergency department. Isolation ward insufficiency and the risk of infection felt by healthcare workers tended to increase in the lower level emergency department. Treatment and transfer delay were higher in the fever and respiratory disease groups (M = 3.58, SD = 1.18; M = 4.08, SD = 0.95), respectively. In all the disease groups, both treatment and transfer were delayed more in Gyeongbuk than in Daegu. Conclusions: Different goals should be pursued by the levels and region of the emergency department to overcome the effects of the COVID-19 pandemic and promote optimal care.

Revised Triage and Surveillance Protocols for Temporary Emergency Department Closures in Tertiary Hospitals as a Response to COVID-19 Crisis in Daegu Metropolitan City.

BACKGROUND: When an emergency-care patient is diagnosed with an emerging infectious disease, hospitals in Korea may temporarily close their emergency departments (EDs) to prevent nosocomial transmission. Since February 2020, multiple, consecutive ED closures have occurred due to the coronavirus disease 2019 (COVID-19) crisis in Daegu. However, sudden ED closures are in contravention of laws for the provision of emergency medical care that enable the public to avail prompt, appropriate, and 24-hour emergency medical care. Therefore, this study ascertained the vulnerability of the ED at tertiary hospitals in Daegu with regard to the current standards. A revised triage and surveillance protocol has been proposed to tackle the current crisis. METHODS: This study was retrospectively conducted at 6 level 1 or 2 EDs in a metropolitan city where ED closure due to COVID-19 occurred from February 18 to March 26, 2020. The present status of ED closure and patient characteristics and findings from chest radiography and laboratory investigations were assessed. Based on the experience from repeated ED closures and the modified systems that are currently used in EDs, revised triage and surveillance protocols have been developed and proposed. RESULTS: During the study period, 6 level 1 or 2 emergency rooms included in the study were shut down 27 times for 769 hours. Thirty-one confirmed COVID-19 cases, of whom 7 died, were associated with the incidence of ED closure. Typical patient presentation with respiratory symptoms of COVID-19 was seen in less than 50% of patients, whereas abnormal findings on chest imaging investigations were detected in 93.5% of the study population. The chest radiography facility, resuscitation rooms, and triage area were moved to locations outside the ED, and a new surveillance protocol was applied to determine the factors warranting quarantine, including symptoms, chest radiographic findings, and exposure to a source of infection. The incidence of ED closures decreased after the implementation of the revised triage and surveillance protocols. CONCLUSION: Triage screening by emergency physicians and surveillance protocols with an externally located chest imaging facility were effective in the early isolation of COVID-19 patients. In future outbreaks of emerging infectious diseases, efforts should be focused toward the provision of continued ED treatment with the implementation of revised triage and surveillance protocols.

Metnase Mediates Loading of Exonuclease 1 onto Single Strand Overhang DNA for End Resection at Stalled Replication Forks.

Stalling at DNA replication forks generates stretches of single-stranded (ss) DNA on both strands that are exposed to nucleolytic degradation, potentially compromising genome stability. One enzyme crucial for DNA replication fork repair and restart of stalled forks in human is Metnase (also known as SETMAR), a chimeric fusion protein consisting of a su(var)3-9, enhancer-of-zeste and trithorax (SET) histone methylase and transposase nuclease domain. We previously showed that Metnase possesses a unique fork cleavage activity necessary for its function in replication restart and that its SET domain is essential for recovery from hydroxyurea-induced DNA damage. However, its exact role in replication restart is unclear. In this study, we show that Metnase associates with exonuclease 1 (Exo1), a 5'-exonuclease crucial for 5'-end resection to mediate DNA processing at stalled forks. Metnase DNA cleavage activity was not required for Exo1 5'-exonuclease activity on the lagging strand daughter DNA, but its DNA binding activity mediated loading of Exo1 onto ssDNA overhangs. Metnase-induced enhancement of Exo1-mediated DNA strand resection required the presence of these overhangs but did not require Metnase's DNA cleavage activity. These results suggest that Metnase enhances Exo1-mediated exonuclease activity on the lagging strand DNA by facilitating Exo1 loading onto a single strand gap at the stalled replication fork.

Endonuclease EEPD1 Is a Gatekeeper for Repair of Stressed Replication Forks.

Replication is not as continuous as once thought, with DNA damage frequently stalling replication forks. Aberrant repair of stressed replication forks can result in cell death or genome instability and resulting transformation to malignancy. Stressed replication forks are most commonly repaired via homologous recombination (HR), which begins with 5' end resection, mediated by exonuclease complexes, one of which contains Exo1. However, Exo1 requires free 5'-DNA ends upon which to act, and these are not commonly present in non-reversed stalled replication forks. To generate a free 5' end, stalled replication forks must therefore be cleaved. Although several candidate endonucleases have been implicated in cleavage of stalled replication forks to permit end resection, the identity of such an endonuclease remains elusive. Here we show that the 5'-endonuclease EEPD1 cleaves replication forks at the junction between the lagging parental strand and the unreplicated DNA parental double strands. This cleavage creates the structure that Exo1 requires for 5' end resection and HR initiation. We observed that EEPD1 and Exo1 interact constitutively, and Exo1 repairs stalled replication forks poorly without EEPD1. Thus, EEPD1 performs a gatekeeper function for replication fork repair by mediating the fork cleavage that permits initiation of HR-mediated repair and restart of stressed forks.

EEPD1 Rescues Stressed Replication Forks and Maintains Genome Stability by Promoting End Resection and Homologous Recombination Repair.

Replication fork stalling and collapse is a major source of genome instability leading to neoplastic transformation or cell death. Such stressed replication forks can be conservatively repaired and restarted using homologous recombination (HR) or non-conservatively repaired using micro-homology mediated end joining (MMEJ). HR repair of stressed forks is initiated by 5' end resection near the fork junction, which permits 3' single strand invasion of a homologous template for fork restart. This 5' end resection also prevents classical non-homologous end-joining (cNHEJ), a competing pathway for DNA double-strand break (DSB) repair. Unopposed NHEJ can cause genome instability during replication stress by abnormally fusing free double strand ends that occur as unstable replication fork repair intermediates. We show here that the previously uncharacterized Exonuclease/Endonuclease/Phosphatase Domain-1 (EEPD1) protein is required for initiating repair and restart of stalled forks. EEPD1 is recruited to stalled forks, enhances 5' DNA end resection, and promotes restart of stalled forks. Interestingly, EEPD1 directs DSB repair away from cNHEJ, and also away from MMEJ, which requires limited end resection for initiation. EEPD1 is also required for proper ATR and CHK1 phosphorylation, and formation of gamma-H2AX, RAD51 and phospho-RPA32 foci. Consistent with a direct role in stalled replication fork cleavage, EEPD1 is a 5' overhang nuclease in an obligate complex with the end resection nuclease Exo1 and BLM. EEPD1 depletion causes nuclear and cytogenetic defects, which are made worse by replication stress. Depleting 53BP1, which slows cNHEJ, fully rescues the nuclear and cytogenetic abnormalities seen with EEPD1 depletion. These data demonstrate that genome stability during replication stress is maintained by EEPD1, which initiates HR and inhibits cNHEJ and MMEJ.

The endonuclease EEPD1 mediates synthetic lethality in RAD52-depleted BRCA1 mutant breast cancer cells.

BACKGROUND: Proper repair and restart of stressed replication forks requires intact homologous recombination (HR). HR at stressed replication forks can be initiated by the 5' endonuclease EEPD1, which cleaves the stalled replication fork. Inherited or acquired defects in HR, such as mutations in breast cancer susceptibility protein-1 (BRCA1) or BRCA2, predispose to cancer, including breast and ovarian cancers. In order for these HR-deficient tumor cells to proliferate, they become addicted to a bypass replication fork repair pathway mediated by radiation repair protein 52 (RAD52). Depleting RAD52 can cause synthetic lethality in BRCA1/2 mutant cancers by an unknown molecular mechanism. METHODS: We hypothesized that cleavage of stressed replication forks by EEPD1 generates a fork repair intermediate that is toxic when HR-deficient cells cannot complete repair with the RAD52 bypass pathway. To test this hypothesis, we applied cell survival assays, immunofluorescence staining, DNA fiber and western blot analyses to look at the correlation between cell survival and genome integrity in control, EEPD1, RAD52 and EEPD1/RAD52 co-depletion BRCA1-deficient breast cancer cells. RESULTS: Our data show that depletion of EEPD1 suppresses synthetic lethality, genome instability, mitotic catastrophe, and hypersensitivity to stress of replication of RAD52-depleted, BRCA1 mutant breast cancer cells. Without HR and the RAD52-dependent backup pathway, the BRCA1 mutant cancer cells depleted of EEPD1 skew to the alternative non-homologous end-joining DNA repair pathway for survival. CONCLUSION: This study indicates that the mechanism of synthetic lethality in RAD52-depleted BRCA1 mutant cancer cells depends on the endonuclease EEPD1. The data imply that EEPD1 cleavage of stressed replication forks may result in a toxic intermediate when replication fork repair cannot be completed.

Synergy between Piezo1 and Piezo2 channels confers high-strain mechanosensitivity to articular cartilage.

Diarthrodial joints are essential for load bearing and locomotion. Physiologically, articular cartilage sustains millions of cycles of mechanical loading. Chondrocytes, the cells in cartilage, regulate their metabolic activities in response to mechanical loading. Pathological mechanical stress can lead to maladaptive cellular responses and subsequent cartilage degeneration. We sought to deconstruct chondrocyte mechanotransduction by identifying mechanosensitive ion channels functioning at injurious levels of strain. We detected robust expression of the recently identified mechanosensitive channels, PIEZO1 and PIEZO2. Combined directed expression of Piezo1 and -2 sustained potentiated mechanically induced Ca(2+) signals and electrical currents compared with single-Piezo expression. In primary articular chondrocytes, mechanically evoked Ca(2+) transients produced by atomic force microscopy were inhibited by GsMTx4, a PIEZO-blocking peptide, and by Piezo1- or Piezo2-specific siRNA. We complemented the cellular approach with an explant-cartilage injury model. GsMTx4 reduced chondrocyte death after mechanical injury, suggesting a possible therapy for reducing cartilage injury and posttraumatic osteoarthritis by attenuating Piezo-mediated cartilage mechanotransduction of injurious strains.

PREVENTING THE CHROMOSOMAL TRANSLOCATIONS THAT CAUSE CANCER.

Approximately half of all cancers harbor chromosomal translocations that can either contribute to their origin or govern their subsequent behavior. Chromosomal translocations by definition can only occur when there are two DNA double-strand breaks (DSBs) on distinct chromosomes that are repaired heterologously. Thus, chromosomal translocations are by their very nature problems of DNA DSB repair. Such DNA DSBs can be from internal or external sources. Internal sources of DNA DSBs that can lead to translocations can occur are inappropriate immune receptor gene maturation during V(D)J recombination or heavy-chain switching. Other internal DNA DSBs can come from aberrant DNA structures, or are generated at collapsed and reversed replication forks. External sources of DNA DSBs that can generate chromosomal translocations are ionizing radiation and cancer chemotherapy. There are several known nuclear and chromatin properties that enhance translocations over homologous chromosome DSB repair. The proximity of the region of the heterologous chromosomes to each other increases translocation rates. Histone methylation events at the DSB also influence translocation frequencies. There are four DNA DSB repair pathways, but it appears that only one, alternative non-homologous end-joining (a-NHEJ) can mediate chromosomal translocations. The rate-limiting, initial step of a-NHEJ is the binding of poly-adenosine diphosphate ribose polymerase 1 (PARP1) to the DSB. In our investigation of methods for preventing oncogenic translocations, we discovered that PARP1 was required for translocations. Significantly, the clinically approved PARP1 inhibitors can block the formation of chromosomal translocations, raising the possibility for the first time that secondary oncogenic translocations can be reduced in high risk patients.

UVB radiation generates sunburn pain and affects skin by activating epidermal TRPV4 ion channels and triggering endothelin-1 signaling.

At our body surface, the epidermis absorbs UV radiation. UV overexposure leads to sunburn with tissue injury and pain. To understand how, we focus on TRPV4, a nonselective cation channel highly expressed in epithelial skin cells and known to function in sensory transduction, a property shared with other transient receptor potential channels. We show that following UVB exposure mice with induced Trpv4 deletions, specifically in keratinocytes, are less sensitive to noxious thermal and mechanical stimuli than control animals. Exploring the mechanism, we find that epidermal TRPV4 orchestrates UVB-evoked skin tissue damage and increased expression of the proalgesic/algogenic mediator endothelin-1. In culture, UVB causes a direct, TRPV4-dependent Ca(2+) response in keratinocytes. In mice, topical treatment with a TRPV4-selective inhibitor decreases UVB-evoked pain behavior, epidermal tissue damage, and endothelin-1 expression. In humans, sunburn enhances epidermal expression of TRPV4 and endothelin-1, underscoring the potential of keratinocyte-derived TRPV4 as a therapeutic target for UVB-induced sunburn, in particular pain.

The DDN catalytic motif is required for Metnase functions in non-homologous end joining (NHEJ) repair and replication restart.

Metnase (or SETMAR) arose from a chimeric fusion of the Hsmar1 transposase downstream of a protein methylase in anthropoid primates. Although the Metnase transposase domain has been largely conserved, its catalytic motif (DDN) differs from the DDD motif of related transposases, which may be important for its role as a DNA repair factor and its enzymatic activities. Here, we show that substitution of DDN(610) with either DDD(610) or DDE(610) significantly reduced in vivo functions of Metnase in NHEJ repair and accelerated restart of replication forks. We next tested whether the DDD or DDE mutants cleave single-strand extensions and flaps in partial duplex DNA and pseudo-Tyr structures that mimic stalled replication forks. Neither substrate is cleaved by the DDD or DDE mutant, under the conditions where wild-type Metnase effectively cleaves ssDNA overhangs. We then characterized the ssDNA-binding activity of the Metnase transposase domain and found that the catalytic domain binds ssDNA but not dsDNA, whereas dsDNA binding activity resides in the helix-turn-helix DNA binding domain. Substitution of Asn-610 with either Asp or Glu within the transposase domain significantly reduces ssDNA binding activity. Collectively, our results suggest that a single mutation DDN(610) → DDD(610), which restores the ancestral catalytic site, results in loss of function in Metnase.

PARP1 is required for chromosomal translocations.

Chromosomal translocations are common contributors to malignancy, yet little is known about the precise molecular mechanisms by which they are generated. Sequencing translocation junctions in acute leukemias revealed that the translocations were likely mediated by a DNA double-strand break repair pathway termed nonhomologous end-joining (NHEJ). There are major 2 types of NHEJ: (1) the classical pathway initiated by the Ku complex, and (2) the alternative pathway initiated by poly ADP-ribose polymerase 1 (PARP1). Recent reports suggest that classical NHEJ repair components repress translocations, whereas alternative NHEJ components were required for translocations. The rate-limiting step for initiation of alternative NHEJ is the displacement of the Ku complex by PARP1. Therefore, we asked whether PARP1 inhibition could prevent chromosomal translocations in 3 translocation reporter systems. We found that 2 PARP1 inhibitors or repression of PARP1 protein expression strongly repressed chromosomal translocations, implying that PARP1 is essential for this process. Finally, PARP1 inhibition also reduced both ionizing radiation-generated and VP16-generated translocations in 2 cell lines. These data define PARP1 as a critical mediator of chromosomal translocations and raise the possibility that oncogenic translocations occurring after high-dose chemotherapy or radiation could be prevented by treatment with a clinically available PARP1 inhibitor.

Follistatin in chondrocytes: the link between TRPV4 channelopathies and skeletal malformations.

Point mutations in the calcium-permeable TRPV4 ion channel have been identified as the cause of autosomal-dominant human motor neuropathies, arthropathies, and skeletal malformations of varying severity. The objective of this study was to determine the mechanism by which TRPV4 channelopathy mutations cause skeletal dysplasia. The human TRPV4(V620I) channelopathy mutation was transfected into primary porcine chondrocytes and caused significant (2.6-fold) up-regulation of follistatin (FST) expression levels. Pore altering mutations that prevent calcium influx through the channel prevented significant FST up-regulation (1.1-fold). We generated a mouse model of the TRPV4(V620I) mutation, and found significant skeletal deformities (e.g., shortening of tibiae and digits, similar to the human disease brachyolmia) and increases in Fst/TRPV4 mRNA levels (2.8-fold). FST was significantly up-regulated in primary chondrocytes transfected with 3 different dysplasia-causing TRPV4 mutations (2- to 2.3-fold), but was not affected by an arthropathy mutation (1.1-fold). Furthermore, FST-loaded microbeads decreased bone ossification in developing chick femora (6%) and tibiae (11%). FST gene and protein levels were also increased 4-fold in human chondrocytes from an individual natively expressing the TRPV4(T89I) mutation. Taken together, these data strongly support that up-regulation of FST in chondrocytes by skeletal dysplasia-inducing TRPV4 mutations contributes to disease pathogenesis.

Methylation of histone H3 lysine 36 enhances DNA repair by nonhomologous end-joining.

Given its significant role in the maintenance of genomic stability, histone methylation has been postulated to regulate DNA repair. Histone methylation mediates localization of 53BP1 to a DNA double-strand break (DSB) during homologous recombination repair, but a role in DSB repair by nonhomologous end-joining (NHEJ) has not been defined. By screening for histone methylation after DSB induction by ionizing radiation we found that generation of dimethyl histone H3 lysine 36 (H3K36me2) was the major event. Using a novel human cell system that rapidly generates a single defined DSB in the vast majority of cells, we found that the DNA repair protein Metnase (also SETMAR), which has a SET histone methylase domain, localized to an induced DSB and directly mediated the formation of H3K36me2 near the induced DSB. This dimethylation of H3K36 improved the association of early DNA repair components, including NBS1 and Ku70, with the induced DSB, and enhanced DSB repair. In addition, expression of JHDM1a (an H3K36me2 demethylase) or histone H3 in which K36 was mutated to A36 or R36 to prevent H3K36me2 formation decreased the association of early NHEJ repair components with an induced DSB and decreased DSB repair. Thus, these experiments define a histone methylation event that enhances DNA DSB repair by NHEJ.

Lower-Body Fractures and the Risk of Dementia: A Nationwide Population-Based Study.

BACKGROUND AND PURPOSE: The association between physical activity and dementia has been shown in various observational studies. We aimed to determine the risk of dementia in the elderly with lower-body fractures. METHODS: We reconstructed a population-based matched cohort from the National Health Insurance Service-Senior Cohort data set that covers 511,953 recipients of medical insurance in South Korea. RESULTS: Overall 53,776 subjects with lower-body fractures were identified during 2006-2012, and triplicate control groups were matched randomly by sex, age, and years from the index date for each subject with a fracture. There were 3,573 subjects (6.6%) with and 7,987 subjects (4.9%) without lower-body fractures who developed dementia from 2008 up to 2015. Lower-body fractures were independently associated with a subsequent dementia diagnosis with a higher adjusted hazard ratio (aHR) (1.55, 95% confidence interval [CI]=1.49-1.62) compared with upper-body fractures (aHR=1.19, 95% CI=1.14-1.23). CONCLUSIONS: These results support the protective role of physical activity against dementia and highlight the importance of promoting fracture prevention in the elderly.

Optimized combination of Cervus nippon (Sika deer), Angelica (Dangui), and Rehmannia (Suk-jihwang) mitigates LPS-induced inflammation: exploring signaling pathways through plasma metabolomics.

This study aimed to determine the optimal combination of three anti-inflammatory materials [i.e., Cervus nippon Temminck (CT), Angelica gigas Nakai (AN), and Rehmannia glutinosa (RG)] for the strongest anti-inflammatory potential. Eighteen combinations of the three materials were tested in LPS-stimulated RAW264.7 cells via assessing nitric oxide (NO). The best combination from in vitro studies was administered to LPS-treated C57BL/6J mice for five days. Subsequently, plasma metabolites were profiled by bioinformatics analyses and validations. As results, 2, 20, and 50 µg/mL of CT, AN, and RG (TM) were the most effective combination suppressing inflammation. In mice, TM mitigated hepatic inflammatory markers. Similarly, the metabolomics indicated that TM may suppress NF-κB signaling pathway, thereby alleviating hepatic inflammation. TM also decreased systemic and hepatic pro-inflammatory cytokines. Collectively, we found the optimal combination of TM for mitigating inflammation; thus further studies on safety, mechanisms, and clinical models are warranted for human applications. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-023-01476-x.

Can endoscopic submucosal dissection technique be an alternative treatment option for a difficult giant (≥ 30 mm) pedunculated colorectal polyp?

BACKGROUND: Snare polypectomy of a giant pedunculated colorectal polyp is sometimes technically demanding, and, therefore, piecemeal resection is inevitable, despite the relative risk of invasive cancer and postpolypectomy bleeding. OBJECTIVE: The aim of this study was to evaluate the efficacy and safety of endoscopic submucosal dissection in comparison with conventional snare polypectomy for giant pedunculated polyps DESIGN AND SETTINGS: We retrospectively reviewed the clinical outcomes and complications of endoscopic polypectomy for giant pedunculated polyps from October 2006 to November 2011. PATIENTS: All the patients who underwent endoscopic submucosal dissection (n = 23) or snare polypectomy (n = 20) for pedunculated polyps ≥ 3 cm were enrolled consecutively. In the case of a giant pedunculated polyp with 1) poor visualization of the stalk, 2) technical difficulties in snare positioning for en bloc resection, or 3) need for trimming of the head, we did not attempt piecemeal snare polypectomy, and we performed endoscopic submucosal dissection instead. (These were arbitrarily defined as "difficult" giant pedunculated polyps.) MAIN OUTCOME MEASURES: Data on the patient's demography, endoscopic and histopathologic findings, clinical outcomes, and complications were analyzed. RESULTS: Among the 43 giant pedunculated polyps, 23 polyps were defined as "difficult" polyps and were removed with endoscopic submucosal dissection. Subpedunculated (stalk <1 cm) type was more common in the "difficult" polyp group (p = 0.01). The overall incidence of cancer was 18.6% (8/43). En bloc resection rates were 100% (23/23) in the endoscopic submucosal dissection group and 90% (18/20) in the snare polypectomy group. The procedure times of snare polypectomy and endoscopic submucosal dissection group did not differ significantly (41.7 ± 13.7 minutes vs 44.9 ± 35.6 minutes, p = 0.70). Postpolypectomy bleeding was noted in 1 case (4.3%) in the endoscopic submucosal dissection group and in 3 cases (15%) in the snare polypectomy group. CONCLUSIONS: Endoscopic submucosal dissection, as well as the snare polypectomy for giant pedunculated polyps, appeared to be effective without major complications and can be an alternative option to achieve en bloc resection, particularly for difficult cases, such as giant subpedunculated polyps.

Mitotic occupancy and lineage-specific transcriptional control of rRNA genes by Runx2.

Regulation of ribosomal RNA genes is a fundamental process that supports the growth of cells and is tightly coupled with cell differentiation. Although rRNA transcriptional control by RNA polymerase I (Pol I) and associated factors is well studied, the lineage-specific mechanisms governing rRNA expression remain elusive. Runt-related transcription factors Runx1, Runx2 and Runx3 establish and maintain cell identity, and convey phenotypic information through successive cell divisions for regulatory events that determine cell cycle progression or exit in progeny cells. Here we establish that mammalian Runx2 not only controls lineage commitment and cell proliferation by regulating genes transcribed by RNA Pol II, but also acts as a repressor of RNA Pol I mediated rRNA synthesis. Within the condensed mitotic chromosomes we find that Runx2 is retained in large discrete foci at nucleolar organizing regions where rRNA genes reside. These Runx2 chromosomal foci are associated with open chromatin, co-localize with the RNA Pol I transcription factor UBF1, and undergo transition into nucleoli at sites of rRNA synthesis during interphase. Ribosomal RNA transcription and protein synthesis are enhanced by Runx2 deficiency that results from gene ablation or RNA interference, whereas induction of Runx2 specifically and directly represses rDNA promoter activity. Runx2 forms complexes containing the RNA Pol I transcription factors UBF1 and SL1, co-occupies the rRNA gene promoter with these factors in vivo, and affects local chromatin histone modifications at rDNA regulatory regions. Thus Runx2 is a critical mechanistic link between cell fate, proliferation and growth control. Our results suggest that lineage-specific control of ribosomal biogenesis may be a fundamental function of transcription factors that govern cell fate.

Endoscopic submucosal dissection for colorectal tumors--1,000 colorectal ESD cases: one specialized institute's experiences.

PURPOSE: Endoscopic submucosal dissection (ESD) is a very useful endoscopic technique, making it possible to perform en bloc resection regardless of lesion size. Since the introduction of ESD at our hospital, we have performed 1,000 colorectal ESDs during 56 months. The purpose of this study was to evaluate the clinical outcomes of our colorectal ESD experience and to access the efficacy and safety of colorectal ESD. METHODS: Between October 2006 and August 2011, we performed ESD on 1,000 consecutive colorectal tumors in 966 patients. We evaluated the clinical outcomes of all said cases. RESULTS: The mean resected tumor size was 24.1 ± 13.3 (3-145) mm. Our overall endoscopic en bloc resection rate was 97.5% (975/1,000), and our R0 resection rate was 91.2% (912/1,000) respectively. Our perforation rate was 5.3% (53/1,000). Of these 53 perforations, 50 cases were treated through conservative management with/without endoscopic clipping, whereas the remaining 3 patients received laparoscopic operation. Pathological examination showed adenocarcinoma in 37.2% of cases (372/1,000) and neuroendocrine tumors in 11.2% (112/1,000). We recommended additional radical surgery to 82 patients who had a risk of lymph node metastasis. Follow-up colonoscopies were performed on 722 patients. During the median follow-up period of 13 (1-62) months, there were three recurrences (0.4%). CONCLUSIONS: ESD is technically difficult, with a substantial risk of perforation. However, ESD enabled en bloc resection and pathologically complete resection of large colorectal epithelial tumors and submucosal tumors. As experience with the technique increases, ESD may gradually replace piecemeal endoscopic mucosal resection and radical colon resection in the treatment of colorectal tumors.