Indications and techniques of biliary drainage for acute cholangitis in updated Tokyo Guidelines 2018

The Tokyo Guidelines 2013 (TG13) include new topics in the biliary drainage section. From these topics, we describe the indications and new techniques of biliary drainage for acute cholangitis with videos. Recently, many novel studies and case series have been published across the world, thus TG13 need to be updated regarding the indications and selection of biliary drainage based on published data. Herein, we describe the latest updated TG13 on biliary drainage in acute cholangitis with meta‐analysis. The present study showed that endoscopic transpapillary biliary drainage regardless of the use of nasobiliary drainage or biliary stenting, should be selected as the first‐line therapy for acute cholangitis. In acute cholangitis, endoscopic sphincterotomy (EST) is not routinely required for biliary drainage alone because of the concern of post‐EST bleeding. In case of concomitant bile duct stones, stone removal following EST at a single session may be considered in patients with mild or moderate acute cholangitis except in patients under anticoagulant therapy or with coagulopathy. We recommend the removal of difficult stones at two sessions after drainage in patients with a large stone or multiple stones. In patients with potential coagulopathy, endoscopic papillary dilation can be a better technique than EST for stone removal. Presently, balloon enteroscopy‐assisted endoscopic retrograde cholangiopancreatography (BE‐ERCP) is used as the first‐line therapy for biliary drainage in patients with surgically altered anatomy where BE‐ERCP expertise is present. However, the technical success rate is not always high. Thus, several studies have revealed that endoscopic ultrasonography‐guided biliary drainage (EUS‐BD) can be one of the second‐line therapies in failed BE‐ERCP as an alternative to percutaneous transhepatic biliary drainage where EUS‐BD expertise is present.     

Three-dimensional studies of the cytoskeleton of cultured hepatocytes: A quick-freezing and deep-etching study

Summary The ultrastructure of the cytoskeleton of cultured mouse hepatocytes was studied by a quick-freezing and deep-etching method. Isolated mouse hepatocytes were cultured on collagen gels for 48 h, fixed in paraformaldehyde and centrifuged to prepare cell pellets. The hepatocytes were split open to remove cytoplasmic soluble proteins for replica preparations. Some specimens were decorated with anti-actin antibody or S₁ myosin fragments to identify actin filaments. They were quickly frozen in isopentane-propane mixture, fractured in liquid nitrogen, deeply etched in a freeze-fracture machine and rotary shadowed by platinum and carbon. The basal cell membranes of hepatocytes were in contact with the collagen gels and the apical surface faced the culture medium. Networks of actin filaments were attached to the apical cell membranes, but intermediate filaments were localized along the basal layer. Some intermediate filaments were associated with cell organelles, such as the endoplasmic reticulum. The Golgi apparatus was less associated with the cytoskeleton and showed synthesized materials in the cisternae. Cytoskeletal organization in cultured hepatocytes was revealed three-dimensionally, indicating that the interaction of cell membranes with collagen gels is important for the organization of the cytoskeleton.     

Successful treatment for infected aortic aneurysm using endovascular aneurysm repairs as a bridge to delayed open surgery

Management of infected aortic aneurysms, which can be life-threatening, remains challenging. Open surgical treatments, including debridement of the infected aorta and the surrounding tissue and either in situ reconstruction or extra-anatomic bypass covering with omentum or muscle flap, are the mainstay of therapy. However, increasing advances in technology have made endovascular treatment of infected aneurysms feasible. The present study describes the first clinical report of successful treatment of an infected aneurysm using endovascular techniques in the acute phase, followed by delayed open surgery.     

Effects of the hydroxyl radical and hydrogen peroxide on tooth bleaching

The mechanisms of bleaching of discolored coronal teeth using hydrogen peroxide (H2O2) were investigated. In a scanning-electron-microscopy study, the intertubular dentin and peritubular dentin were dissolved by high concentrations of H2O2, which is used for bleaching. The X-ray diffraction study showed that hydroxyapatite was not influenced by H2O2. In an electron-spin-resonance study, more hydroxyl radical (* OH) was detected as the H2O2 concentration was increased. When amino acids that are core components of dentin proteins, such as proline and alanine, were added to H2O2, the generation of * OH decreased, but there was no change when glycine was added. A nuclear-magnetic-resonance study showed that proline was degraded completely by H2O2, the structure of alanine changed slightly, and glycine was not affected by H2O2. It is suggested that H2O2 and * OH do not influence the inorganic tissue of dentin but attack the organic component of dentin. These facts suggest that * OH has the main role in tooth bleaching with H2O2.     

Identification and functional characterization of a sex pheromone receptor in the silkmoth Bombyx mori

Sex pheromones released by female moths are detected with high specificity and sensitivity in the olfactory sensilla of antennae of conspecific males. Bombykol in the silkmoth Bombyx mori was the first sex pheromone to be identified. Here we identify a male-specific G protein-coupled olfactory receptor gene, B. mori olfactory receptor 1 (BmOR-1), that appears to encode a bombykol receptor. The BmOR-1 gene is located on the Z sex chromosome, has an eight-exon/seven-intron structure, and exhibits male-specific expression in the pheromone receptor neurons of male moth antenna during late pupal and adult stages. Bombykol stimulation of Xenopus laevis oocytes expressing BmOR-1 and BmGalphaq elicited robust dose-dependent inward currents on two-electrode voltage clamp recordings, demonstrating that the binding of bombykol to BmOR-1 leads to the activation of a BmGalphaq-mediated signaling cascade. Antennae of female moths infected with BmOR-1-recombinant baculovirus showed electrophysiological responses to bombykol but not to bombykal. These results provide evidence that BmOR-1 is a G protein-coupled sex pheromone receptor that recognizes bombykol.     

Multiple modes of action of tacrolimus (FK506) for neuroprotective action on ischemic damage after transient focal cerebral ischemia in rats

While the immunosuppressant tacrolimus (FK506) is known to be neuroprotective following cerebral ischemia, the mechanisms underlying its neuroprotective properties are not fully understood. To determine the mode of action by which tacrolimus ameliorates neurodegeneration after transient focal ischemia, we therefore evaluated the effect of tacrolimus on DNA damage, release of cytochrome c, activation of microglia and infiltration of neutrophils following a 60-min occlusion of the middle cerebral artery (MCA) in rats. In this model, cortical brain damage gradually expanded until 24 h after reperfusion, whereas brain damage in the caudate putamen was fully developed within 5 h. Tacrolimus (1 mg/kg) administered immediately after MCA occlusion significantly reduced ischemic damage in the cerebral cortex, but not in the caudate putamen. Tacrolimus decreased both apoptotic and necrotic cell death at 24 h and reduced the number of cytochrome c immunoreactive cells at 8 h after reperfusion in the ischemic penumbra in the cerebral cortex. In contrast, tacrolimus did not show significant neuroprotection for necrotic cell death and reduction of cytochrome c immunoreactive cells in the caudate putamen. Tacrolimus also significantly decreased microglial activation at 8 h and inflammatory markers (cytokine-induced neutrophil chemoattractant and myeloperoxidase [MPO] activity) at 24 h after reperfusion in the ischemic cortex but not in the caudate putamen. These results collectively suggest that tacrolimus ameliorates the gradually expanded brain damage by inhibiting both apoptotic and necrotic cell death, as well as suppressing inflammatory reactions.     

SLFN11 promotes CDT1 degradation by CUL4 in response to replicative DNA damage,while its absence leads to synthetic lethality with ATR/CHK1 inhibitors

Schlafen-11 (SLFN11) inactivation in ∼50% of cancer cells confers broad chemoresistance. To identify therapeutic targets and underlying molecular mechanisms for overcoming chemoresistance, we performed an unbiased genome-wide RNAi screen in SLFN11-WT and -knockout (KO) cells. We found that inactivation of Ataxia Telangiectasia- and Rad3-related (ATR), CHK1, BRCA2, and RPA1 overcome chemoresistance to camptothecin (CPT) in SLFN11-KO cells. Accordingly, we validate that clinical inhibitors of ATR (M4344 and M6620) and CHK1 (SRA737) resensitize SLFN11-KO cells to topotecan, indotecan, etoposide, cisplatin, and talazoparib. We uncover that ATR inhibition significantly increases mitotic defects along with increased CDT1 phosphorylation, which destabilizes kinetochore-microtubule attachments in SLFN11-KO cells. We also reveal a chemoresistance mechanism by which CDT1 degradation is retarded, eventually inducing replication reactivation under DNA damage in SLFN11-KO cells. In contrast, in SLFN11-expressing cells, SLFN11 promotes the degradation of CDT1 in response to CPT by binding to DDB1 of CUL4^CDT2 E3 ubiquitin ligase associated with replication forks. We show that the C terminus and ATPase domain of SLFN11 are required for DDB1 binding and CDT1 degradation. Furthermore, we identify a therapy-relevant ATPase mutant (E669K) of the SLFN11 gene in human TCGA and show that the mutant contributes to chemoresistance and retarded CDT1 degradation. Taken together, our study reveals new chemotherapeutic insights on how targeting the ATR pathway overcomes chemoresistance of SLFN11-deficient cancers. It also demonstrates that SLFN11 irreversibly arrests replication by degrading CDT1 through the DDB1–CUL4^CDT2 ubiquitin ligase.

Schlafen-11 (SLFN11) is an emergent restriction factor against genomic instability acting by eliminating cells with replicative damage (1–6) and potentially acting as a tumor suppressor (6, 7). SLFN11-expressing cancer cells are consistently hypersensitive to a broad range of chemotherapeutic drugs targeting DNA replication, including topoisomerase inhibitors, alkylating agents, DNA synthesis, and poly(ADP-ribose) polymerase (PARP) inhibitors compared to SLFN11-deficient cancer cells, which are chemoresistant (1, 2, 4, 8–17). Profiling SLFN11 expression is being explored for patients to predict survival and guide therapeutic choice (8, 13, 18–24).The Cancer Genome Atlas (TCGA) and cancer cell databases demonstrate that SLFN11 mRNA expression is suppressed in a broad fraction of common cancer tissues and in ∼50% of all established cancer cell lines across multiple histologies (1, 2, 5, 8, 13, 25, 26). Silencing of the SLFN11 gene, like known tumor suppressor genes, is under epigenetic mechanisms through hypermethylation of its promoter region and activation of histone deacetylases (HDACs) (21, 23, 25, 26). A recent study in small-cell lung cancer patient-derived xenograft models also showed that SLFN11 gene silencing is caused by local chromatin condensation related to deposition of H3K27me3 in the gene body of SLFN11 by EZH2, a histone methyltransferase (11). Targeting epigenetic regulators is therefore an attractive combination strategy to overcome chemoresistance of SLFN11-deficient cancers (10, 25, 26). An alternative approach is to attack SLFN11-negative cancer cells by targeting the essential pathways that cells use to overcome replicative damage and replication stress. Along these lines, a prior study showed that inhibition of ATR (Ataxia Telangiectasia- and Rad3-related) kinase reverses the resistance of SLFN11-deficient cancer cells to PARP inhibitors (4). However, targeting the ATR pathway in SLFN11-deficient cells has not yet been fully explored.SLFN11 consists of two functional domains: A conserved nuclease motif in its N terminus and an ATPase motif (putative helicase) in its C terminus (2, 6). The N terminus nuclease has been implicated in the selective degradation of type II tRNAs (including those coding for ATR) and its nuclease structure can be derived from crystallographic analysis of SLFN13 whose N terminus domain is conserved with SLFN11 (27, 28). The C terminus is only present in the group III Schlafen family (24, 29). Its potential ATPase activity and relationship to chemosensitivity to DNA-damaging agents (3–5) imply that the ATPase/helicase of SLFN11 is involved specifically in DNA damage response (DDR) to replication stress. Indeed, inactivation of the Walker B motif of SLFN11 by the mutation E669Q suppresses SLFN11-mediated replication block (5, 30). In addition, SLFN11 contains a binding site for the single-stranded DNA binding protein RPA1 (replication protein A1) at its C terminus (3, 31) and is recruited to replication damage sites by RPA (3, 5). The putative ATPase activity of SLFN11 is not required for this recruitment (5) but is required for blocking the replication helicase complex (CMG-CDC45) and inducing chromatin accessibility at replication origins and promoter sites (5, 30). Based on these studies, our current model is that SLFN11 is recruited to “stressed” replication forks by RPA filaments formed on single-stranded DNA (ssDNA), and that the ATPase/helicase activity of SLFN11 is required for blocking replication progression and remodeling chromatin (5, 30). However, underlying mechanisms of how SLFN11 irreversibly blocks replication in DNA damage are still unclear.Increased RPA-coated ssDNA caused by DNA damage and replication fork stalling also triggers ATR kinase activation, promoting subsequent phosphorylation of CHK1, which transiently halts cell cycle progression and enables DNA repair (32). ATR inhibitors are currently in clinical development in combination with DNA replication damaging drugs (33, 34), such as topoisomerase I (TOP1) inhibitors, which are highly synergistic with ATR inhibitors in preclinical models (35). ATR inhibitors not only inhibit DNA repair, but also lead to unscheduled replication origin firing (36), which kills cancer cells (37, 38) by inducing genomic alterations due to faulty replication and mitotic catastrophe (33).The replication licensing factor CDT1 orchestrates the initiation of replication by assembling prereplication complexes (pre-RC) in G1-phase before cells enter S-phase (39). Once replication is started by loading and activation of the MCM helicase, CDT1 is degraded by the ubiquitin proteasomal pathway to prevent additional replication initiation and ensure precise genome duplication and the firing of each origin only once per cell cycle (39, 40). At the end of G2 and during mitosis, CDT1 levels rise again to control kinetochore-microtubule attachment for accurate chromosome segregation (41). Deregulated overexpression of CDT1 results in rereplication, genome instability, and tumorigenesis (42). The cellular CDT1 levels are tightly regulated by the damage-specific DNA binding protein 1 (DDB1)–CUL4^CDT2 E3 ubiquitin ligase complex in G1-phase (43) and in response to DNA damage (44, 45). How CDT1 is recognized by CUL4^CDT2 in response to DNA damage remains incompletely known.In the present study, starting with a human genome-wide RNAi screen, bioinformatics analyses, and mechanistic validations, we explored synthetic lethal interactions that overcome the chemoresistance of SLFN11-deficient cells to the TOP1 inhibitor camptothecin (CPT). The strongest synergistic interaction was between depletion of the ATR/CHK1-mediated DNA damage response pathways and DNA-damaging agents in SLFN11-deficient cells. We validated and expanded our molecular understanding of combinatorial strategies in SLFN11-deficient cells with the ATR (M4344 and M6620) and CHK1 (SRA737) inhibitors in clinical development (33, 46, 47) and found that ATR inhibition leads to CDT1 stabilization and hyperphosphorylation with mitotic catastrophe. Our study also establishes that SLFN11 promotes the degradation of CDT1 by binding to DDB1, an adaptor molecule of the CUL4^CDT2 E3 ubiquitin ligase complex, leading to an irreversible replication block in response to replicative DNA damage.     

Chromosome analysis of human refrozen embryos following fluorescence in situ hybridization

Purpose  Several recent reports have discussed refrozen and thawed embryo transfer; however, the process may cause a degree of chromosomal damage and subtle genomic mutation. In view of this possibility, the purpose of this study was to investigate the incidence of aneuploidy in refrozen embryos. Methods  In order to investigate the incidence of aneuploidy and mosaicism observed in chromosome 1, fluorescent in situ hybridization (FISH) was used on surviving embryos that first underwent one freeze-thaw cycle, then were allowed to develop to the blastocyst stage, and subsequently survived a second freeze-thaw cycle. Results  Of 1,132 blastomeric nuclei analyzed from 15 refrozen embryos, disomy was found in 82.9%. In contrast, for the 11 blastocysts subjected to only one freeze-thaw cycle, disomy was noted in 78.4%. Of the 197 blastomeric nuclei analyzed in all arrested embryos, disomy was found in 51.8%. Conclusions  The refreezing process did not increase aneuploidy. The good and fair morphology groups demonstrated a higher percentage of disomy than the poor morphology group regardless of whether they were frozen once or twice.