Endoscopic Removal and Conservative Treatment of a Small Bowel Perforation Caused by a Toothpick: A Case Report.

This case report describes a unique instance of small bowel perforation in a 49-year-old woman caused by an ingested toothpick. Initially suspected of colonic diverticulitis, a final diagnosis of small bowel perforation was made later, and the toothpick was successfully removed via endoscopy. This case emphasizes the need to consider foreign body ingestion in the differential diagnosis of abdominal pain and demonstrates the feasibility of conservative endoscopic approaches in similar cases.

Impact of time from diagnosis to chemotherapy on prognosis in advanced pancreatic cancer.

BACKGROUND: Due to the aggressive nature and poor prognosis of advanced pancreatic cancer, prompt initiation of treatment is critical. We investigated the effect of the interval between cancer diagnosis and initiation of chemotherapy on survival in patients with advanced pancreatic cancer. METHODS: In this retrospective, single-centre study, consecutive patients with advanced pancreatic cancer between April 2013 and March 2022 were analyzed. Data were extracted from the electronic medical records of patients who received chemotherapy for metastatic, locally advanced or resectable pancreatic cancer or who received chemotherapy due to either being intolerant of or declining surgery. We compared overall survival between two groups: the early waiting time group (waiting time ≤30 days from diagnosis to chemotherapy initiation) and the elective waiting time group (waiting time ≥31 days). Prognostic factors, including biliary drainage, were considered. The impact of waiting time on survival was assessed by univariate and multivariate analyses with Cox proportional hazard models. A 1:1 propensity score matching approach was used to balance bias, accounting for significant poor prognosis factors, age and sex. RESULTS: The study involved 137 patients. Overall survival exhibited no statistically significant difference between the early and elective waiting time groups (207 and 261 days, P = 0.2518). Univariate and multivariate analyses identified poor performance status and metastasis presence as predictors of worse prognosis. This finding persisted post propensity score matching (275 and 222 days, P = 0.8223). CONCLUSIONS: Our study revealed that initiating chemotherapy ˃30 days later does not significantly affect treatment efficacy compared to within 30 days of diagnosis.

5-Aminosalicylic Acid-Induced Liver Injury in a Patient with Ulcerative Colitis: A Case Report.

Introduction: Drug-induced liver injury (DILI) associated with 5-aminosalicylic acid (5-ASA) is a rare but potentially life-threatening adverse event. Case Presentation: We report the case of a 58-year-old woman with ulcerative colitis who developed DILI after initiating maintenance therapy with the multimatrix system 5-ASA. The patient presented with grade 4 liver enzyme elevation on day 98 after initiating 5-ASA and was admitted to the hospital. Blood tests revealed the mixed liver injury, and imaging studies showed no abnormalities except for mild lymph node enlargement. Liver biopsy revealed acute lobular hepatitis with interfacial activity. The patient's score on the International Autoimmune Hepatitis Group 1999 revised scoring system was a total score of 10, causing a suspicion for the diagnosis of autoimmune hepatitis. The DDW-J 2004 scale calculated a total score of six, indicating a high probability of DILI. We suspected DILI due to 5-ASA, and the 5-ASA formulations were discontinued. The patient was treated with ursodeoxycholic acid and neominophagen C, and her liver function gradually improved without steroid treatment. Finally, we definitively diagnosed DILI based on the pathological findings and clinical course after discontinuation of 5-ASA. Conclusion: This case highlights the importance of monitoring liver function in patients receiving 5-ASA therapy.

Drug-induced Interstitial Nephritis in a Patient with Ulcerative Colitis Treated with 5-Aminosalicylic Acid.

This report describes the case of a 76-year-old man with ulcerative colitis who developed interstitial nephritis after starting 5-Aminosalicylic acid (5-ASA) therapy. The patient experienced an initial improvement in symptoms, but developed fatigue, anorexia, and severe renal dysfunction 2.5 months later. Renal biopsy confirmed drug-induced interstitial nephritis, and conservative treatment with fluid replacement and the discontinuation of 5-ASA improved the patient's condition. Clinicians should monitor patients receiving 5-ASA therapy for potential adverse effects, particularly renal injury, and promptly investigate symptoms of renal dysfunction. Early recognition and discontinuation of the offending agent may prevent further damage and improve patient outcomes.

Impact of Initial Body Weight Loss on Prognosis in Advanced Pancreatic Cancer: Insights From a Single-Center Retrospective Study.

BACKGROUND: Pancreatic cancer (PC) has a poor prognosis, with body weight loss commonly observed at diagnosis. However, the impact on PC prognosis of weight loss at the time of diagnosis on PC prognosis is unknown. METHODS: This retrospective, single-center study enrolled consecutively patients diagnosed with metastatic or locally advanced PC or resectable PC who were intolerant of or refused surgery. Patients who had lost more than 5% of their body weight or more than 2% and had a body mass index (BMI) of less than 20 kg/m2 at diagnosis were classified as experiencing body weight loss. Patients were subclassified into 2 groups: patients with and without weight loss. The study evaluated patient-related and PC-related factors affecting prognosis. Cox proportional hazards models were used to assess factors affecting prognosis. The primary endpoint was overall survival. Additionally, 1:1 propensity score matching was performed to reduce bias. RESULTS: In total, 220 patients were included in the study. The median age of the patients was 74 years, and 49.1% were male. Weight loss at diagnosis was observed in 43.2% of patients. There were no significant differences in clinical factors, except for anthropometric parameters, between the groups. The median survival time did not differ between the weight loss and no weight loss groups (149 and 173 days, respectively, P = .669). After matching, no significant differences in survival times were observed between the 2 groups. CONCLUSIONS: This study found no association between weight loss at diagnosis and prognosis in patients with advanced PC treated with best supportive care or chemotherapy.

Gastrointestinal symptoms in 609 Japanese patients with COVID-19: a single-center retrospective study.

BACKGROUND: GI symptoms are common in acute COVID-19 patients. This study aimed to characterize the GI symptoms occurring in Japanese COVID-19 patients. METHODS: This retrospective single-center cohort study included 751 hospitalized acute COVID-19 patients. The primary outcomes were the frequency and severity of GI symptoms. The secondary outcomes included the association between COVID-19 severity and GI symptoms and the timing of GI symptom onset. RESULTS: After exclusion, the data of 609 patients were analyzed. The median age was 62 years, and 55% were male. The median time from initial symptom onset to admission was five days. On admission, 92% of the patients had fever, 35.1% had fatigue, 75% had respiratory symptoms, and 75% had pneumonia. The sample included patients with mild (19%), moderate (59%), and severe COVID-19 (22%). A total of 218 patients (36%) had GI symptoms, of which 93% were classified as grade 1/2; 170 patients had both respiratory and GI symptoms. Diarrhea was the most frequent GI symptom, occurring in 170 patients, followed by anorexia in 73 patients and nausea/vomiting in 36 patients, and abdominal pain in 8 patients. There was no significant relationship between COVID-19 severity and GI symptoms. Among COVID-19 patients with both GI and respiratory symptoms, 48% had respiratory symptoms preceding GI symptoms, 25% had GI symptoms preceding respiratory symptoms and 27% had a simultaneous onset of respiratory and GI symptoms. CONCLUSION: Thirty-six percent of the Japanese COVID-19 patients had GI symptoms; diarrhea was the most frequent GI symptom but did not predict severe COVID-19.

Antithrombotic drug use does not affect the fecal immunochemical test PPV for colorectal cancer, but warfarin may have an impact in a Japanese cohort.

BACKGROUND: The fecal immunochemical test (FIT) is used for colorectal cancer (CRC) screening. Patients on antithrombotic drugs (ATs) are often screened for CRC, but the effect of ATs on FIT results is controversial. METHODS: We divided individuals with FIT-positive results into two groups, patients treated with and without ATs, and retrospectively compared invasive CRC rates, advanced neoplasia detection rates (ANDRs), adenoma detection rates (ADRs), and polyp detection rates (PDRs) between the two groups. We evaluated the factors influencing the FIT positive predictive value (PPV) using propensity matching, adjusting for age, sex, and bowel preparation. RESULTS: We enrolled 2327 individuals (54.9% male; mean age, 66.7  ± â€Š12.7 years). We grouped 463 individuals into the AT user group and 1864 into the nonuser group. Patients in the AT user group were significantly older and more likely to be male. After propensity score matching for age, sex, and Boston bowel preparation scale, the ADR and PDR in the AT user group were significantly lower than those in the nonuser group. Univariate logistic analysis revealed that multiple AT use (odds ratio [OR]: .39, p < 0.001) had the lowest OR for FIT PPV, followed by age- and sex-adjusted factors for the ADR and any AT use (OR: .67, p = 0.0007). No significant factors related to AT use were observed among age-adjusted predictive factors for invasive CRC, but warfarin use was a borderline significant positive predictive factor (OR: 2.23, p = 0.059). CONCLUSION: AT use may not affect the PPV for detecting invasive CRC in patients with positive FIT results, but warfarin may have an impact.

Crystal Structure of Pyrrolysyl-tRNA Synthetase from a Methanogenic Archaeon ISO4-G1 and Its Structure-Based Engineering for Highly-Productive Cell-Free Genetic Code Expansion with Non-Canonical Amino Acids.

Pairs of pyrrolysyl-tRNA synthetase (PylRS) and tRNAPyl from Methanosarcina mazei and Methanosarcina barkeri are widely used for site-specific incorporations of non-canonical amino acids into proteins (genetic code expansion). Previously, we achieved full productivity of cell-free protein synthesis for bulky non-canonical amino acids, including Nε-((((E)-cyclooct-2-en-1-yl)oxy)carbonyl)-L-lysine (TCO*Lys), by using Methanomethylophilus alvus PylRS with structure-based mutations in and around the amino acid binding pocket (first-layer and second-layer mutations, respectively). Recently, the PylRS·tRNAPyl pair from a methanogenic archaeon ISO4-G1 was used for genetic code expansion. In the present study, we determined the crystal structure of the methanogenic archaeon ISO4-G1 PylRS (ISO4-G1 PylRS) and compared it with those of structure-known PylRSs. Based on the ISO4-G1 PylRS structure, we attempted the site-specific incorporation of Nε-(p-ethynylbenzyloxycarbonyl)-L-lysine (pEtZLys) into proteins, but it was much less efficient than that of TCO*Lys with M. alvus PylRS mutants. Thus, the first-layer mutations (Y125A and M128L) of ISO4-G1 PylRS, with no additional second-layer mutations, increased the protein productivity with pEtZLys up to 57 ± 8% of that with TCO*Lys at high enzyme concentrations in the cell-free protein synthesis.

Predictive factors of collateral vessel development induced by oxaliplatin-based chemotherapy.

BACKGROUND AND AIM: Oxaliplatin can lead to hepatic sinusoidal injury, called hepatic sinusoidal obstruction syndrome (SOS), resulting in portal hypertension-related complications. This could worsen the clinical course of the patients treated with oxaliplatin. Early diagnosis is challenging. We explored predictive markers of oxaliplatin-induced collateral vessels. METHODS: Patients who received oxaliplatin-based chemotherapy were retrospectively screened. We evaluated their laboratory findings and spleen size on computed tomography immediately before oxaliplatin-based chemotherapy and after 6 months of treatment. The primary outcome was collateral vessel development, as a surrogate marker for oxaliplatin-induced SOS in patients who underwent oxaliplatin-based chemotherapy. The secondary outcome was the identification of factors that predicted the development of collateral vessels. RESULTS: We enrolled 161 patients who received oxaliplatin-based chemotherapy. They had a median age of 69 years, and 63.3% were men. Collateral vessels developed in nine (5.6%) patients during the study period. After oxaliplatin-based chemotherapy, the spleen size increased in 104 patients (64.6%), with a ≥ 30% increase in 19.4% of the patients. Univariate analysis showed that the Fibrosis-4 (FIB-4) index (≥ 1.76; OR 9.17), aspartate aminotransferase:platelet ratio index (APRI) (≥ 0.193; OR 9.62), cumulative dose of oxaliplatin (≥ 1000 mg; OR 8.43), and increase in spleen size (≥ 30%; OR 6.01) were significant risk factors for collateral vessel development. Multivariate analysis after stepwise selection revealed that the FIB-4 index and spleen size were significant independent predictive factors. CONCLUSION: A ≥ 1.76 increase in the FIB-4 index and a ≥ 30% increase in spleen size after 6 months of oxaliplatin-based chemotherapy were significant predictive markers for collateral vessel development.

Stratification Based on Risk Factors at Diagnosis Could Predict Progression in Patients with Pancreatic Cysts.

BACKGROUND: Predicting the risk of malignant transformation in pancreatic cyst patients is challenging. AIM: We retrospectively investigated the risk factors for malignant transformation in pancreatic cyst patients. METHODS: Patients with pancreatic cysts diagnosed using imaging tests were followed from November 2008 to December 2021. A significant change was defined as the additional development of high-risk stigmata (HRS), worrisome features (WFs), or pancreatic cancer during monitoring. RESULTS: In total, 479 patients were analyzed, with a median observation period of 50 months. Forty-four patients (9.2%) showed significant changes, and eight (1.7%) developed pancreatic cancer. The univariate analysis showed that the cyst diameter at diagnosis (≥ 14 mm), main pancreatic duct (MPD) diameter at diagnosis (≥ 3 mm), presence of multilocular cysts, and an inconsistent MPD caliber were significant predictive factors for a significant change. One point was assigned for each significant factor. We grouped the patients into three groups: the low-risk group (total score 0), medium-risk group (score 1-2), and high-risk group (score 3-4). The high-risk group had a higher risk of a significant change than the medium- and low-risk groups (age-adjusted HRs for the medium-risk and high-risk groups were 3.0 and 5.2 compared with the low-risk group). CONCLUSION: Stratification based on risk factors may help predict the development of significant changes in pancreatic cyst patients.

Impact of anticoagulants on the clinical outcomes of colonic diverticular bleeding comparing warfarin and direct oral anticoagulants.

Recently, direct oral anticoagulants (DOACs) have been widely used as antithrombotic agents to replace warfarin, but their clinical impact in patients with gastrointestinal bleeding is unclear. We compared the effects of warfarin and DOACs on the outcomes of patients with colonic diverticular bleeding. The patients were divided into warfarin and DOAC groups. We compared the clinical outcomes and the effect of the DOAC dosing and examined any readmissions due to colonic diverticular bleeding within 1 year. A total of 95 events (warfarin group: n = 43 and DOAC group: n = 52) were included. Compared with the warfarin group, the DOAC group was significantly older, had a lower rate of concomitant antiplatelet agents, and a shorter hospital stay, but no significant differences were found in the other clinical outcomes. Thirty-seven patients (71.2%) in the DOAC group had appropriate dosing, whereas 15 patients (28.9%) had an inappropriate dose. The patients with overdose or contraindications had significantly lower minimum hemoglobin levels. In the univariate analysis, prior hospitalization for colonic diverticular bleeding was a significant predictor of readmission. Compared with warfarin, patients with colonic diverticular bleeding treated with DOACs were older and had shorter hospital stays, and the inappropriate use of DOACs may worsen outcomes.

Effect of heat-moisture treated brown rice crackers on postprandial flow-mediated dilation in adults with mild endothelial dysfunction.

Background: Endothelial dysfunction is an early pathophysiological feature and independent predictor of a poor prognosis in most forms of cardiovascular disease. We evaluated the effect of brown rice crackers (BR-C) on endothelial function. Methods: Effect of heat-moisture treated (HMT) -BR-C on postprandial flow-mediated dilation (FMD) in adults with mild endothelial dysfunction was compared with that of BR-C and white rice crackers (WR-C) in 12 adults with mild endothelial dysfunction (less than 7.0% of FMD) by a randomized, single-blind, three-treatment three-period crossover trial (UMIN 000034898). Since we considered that the FMD increase was associated with the treatment of HMT-BR-C, we examined the effect of three possible factors: postprandial glucose levels, polyphenol content, and polyphenol release from the food matrix. Results: Mean pre-intake baseline FMD values of HMT-BR-C, BR-C, and WR-C were 4.9%, 5.1%, and 4.9%, respectively, and those values 1 h post-intake were 6.3%, 5.1%, and 4.8%, respectively. There was no difference in intergroup comparisons of FMD using Dunnett's multiple comparison test. There was a significant increase in FMD only in HMT-BR-C in intragroup comparisons (P = 0.042 by paired-t test). In comparison with BR-C, no significant difference was noted in the postprandial glucose level nor in the content of total polyphenols and ferulic acid derivatives in HMT-BR-C. However, the 70% ethanol extracted from HMT-BR-C contained a significantly larger amount of free and bound ferulic acids than from BR-C. Conclusion: HMT-BR-C intake increased the postprandial FMD response.

Nivolumab dose escalation triggered immune checkpoint inhibitor-induced colitis after 147 weeks of prolonged stable use in a patient with lung cancer: a case report.

A 56-year-old man with advanced lung adenocarcinoma presented to the emergency department with a 6-day history of diarrhea. He was treated for lung cancer with nivolumab 3 mg/kg (144 mg/body) every 2 weeks (Q2W), followed by an increase to 240 mg Q2W for 147 weeks, for a total of 69 administrations. His dose was then increased to 480 mg/body every four weeks (Q4W) 12 days before his presentation. Clostridioides difficile toxin, cytomegalovirus antigenemia, and stool bacterial cultures were negative. Colonoscopy revealed diffusely edematous granular mucosa with mucosal redness, exudates, loss of vascular pattern, and aphtha throughout the colon but no ulcers. We diagnosed the patient with immune checkpoint inhibitor-induced colitis. We started prednisolone at a dose of 60 mg/day. His symptoms gradually improved, and he recovered without diarrhea on day ten after hospitalization. After prednisolone tapering, his symptoms did not worsen. Colonoscopy showed significant improvement on day 29, and the diffuse redness disappeared. The patient did not experience subsequent recurrence of diarrhea. He had no progression of lung cancer despite the termination of nivolumab for seven months. Here, we report a case of lung cancer in which nivolumab dose escalation after prolonged stable use triggered immune checkpoint inhibitor-induced colitis.

The First Transileocolic Obliteration for Refractory Esophageal Varices: A Case Report and Review of the Literature.

Transileocolic obliteration (TIO) is a useful treatment for gastric, duodenal, or rectal varices. However, TIO for esophageal varices has not yet been reported. We herein report successful TIO performed for refractory esophageal varices with a large paraesophageal vein, with no subsequent recurrence of varices.

Classification and clinical features of adverse drug reactions in patients with ulcerative colitis treated with 5-aminosalicylate acid: a single-center, observational study.

BACKGROUND: 5-Aminosalicylate acid (5-ASA) is a crucial drug for ulcerative colitis (UC) patients. 5-ASA has several side effects. However, the types of side effects vary and are sometimes severe. METHODS: A single-center, retrospective cohort study was conducted from September 2001 to June 2020. We surveyed consecutive UC patients who visited our hospital and investigated adverse drug reactions (ADRs) related to 5-ASA formulations. We grouped patients into four subgroups: (1) lupus-like symptoms, (2) blood test abnormalities, (3) mimicking IBD exacerbation and (4) others. Their clinical courses were evaluated. RESULTS: We surveyed 288 consecutive UC patients, 35 of whom developed ADRs of any grade (12.9%), and analyzed 27 patients. The median age and 5-ASA doses were 43 years and 4000 mg, respectively, and 48% were male. The ADR triggers were the first use of 5-ASA (n = 17, 63%), 5-ASA switch (n = 9, 33%) and 5-ASA dose escalation (n = 1, 3.7%). The median time to ADR was 15 days (IQR: 7, 63). Ten patients (37%) had grade 3/4 ADRs. Fever was the most common ADR (n = 6, 23%), followed by hyperamylasemia and headache (n = 4, 15%). Lupus-like symptoms accounted for 56% (n = 15), blood test abnormalities for 26% (n = 7), mimicking IBD exacerbation for 15% (n = 4) and others for 3.7% (n = 1). The time to ADR was shorter in the mimicking IBD exacerbation group (median 11 days) than in the lupus-like symptoms (22 days) and blood test abnormalities (55 days) groups. CONCLUSION: Classification of ADRs related to 5-ASA into four groups might lead to early recognition of ADRs.

Human adiponectin receptor AdipoR1 assumes closed and open structures.

The human adiponectin receptors, AdipoR1 and AdipoR2, are key anti-diabetic molecules. We previously reported the crystal structures of human AdipoR1 and AdipoR2, revealing that their seven transmembrane helices form an internal closed cavity (the closed form). In this study, we determined the crystal structure of the D208A variant AdipoR1, which is fully active with respect to the major downstream signaling. Among the three molecules in the asymmetric unit, two assume the closed form, and the other adopts the open form with large openings in the internal cavity. Between the closed- and open-form structures, helices IV and V are tilted with their intracellular ends shifted by about 4 and 11 Å, respectively. Furthermore, we reanalyzed our previous wild-type AdipoR1 diffraction data, and determined a 44:56 mixture of the closed and open forms, respectively. Thus, we have clarified the closed-open interconversion of AdipoR1, which may be relevant to its functional mechanism(s).

Structural Basis of Activin Receptor-Like Kinase 2 (R206H) Inhibition by Bis-heteroaryl Pyrazole-Based Inhibitors for the Treatment of Fibrodysplasia Ossificans Progressiva Identified by the Integration of Ligand-Based and Structure-Based Drug Design Approaches.

Fibrodysplasia ossificans progressiva (FOP) is a rare but severe genetic disorder in which acute inflammation elicits progressive heterotopic ossification in the muscles, tendons, and ligaments. Classic FOP is caused by the R206H mutation in ALK2/ACVR1. While several activin receptor-like kinase 2 (ALK2) inhibitors were found to be efficacious in animal models of FOP, most of the ALK2 (R206H) inhibitors lacked sufficient oral bioavailability for efficacy. Previously, the synthesis of a series of novel bis-heteroaryl pyrazole-based ALK2 (R206H) inhibitors that achieved both substantial potency and an improved ADMET profile was reported. In the present study, the detailed procedure of the in silico approach employed to identify the initial bis-heteroaryl pyrazole-based ALK2 (R206H) inhibitor RK-59638 and the analysis of the ALK2 (R206H) RK-59638 complex structure to guide the synthetic optimization of the chemical series, obtaining RK-71807 showing improved potency and metabolic stability, were described. According to the initial in silico screening, the screening efficiencies and chemical diversity of the hit compounds of both ligand-based and structure-based methods were evaluated. Then, X-ray structures of ALK2 (R206H) and the inhibitors were analyzed to assess the structure-activity relationships of the synthesized compounds. The 3D-RISM analysis indicated the existence of the additional hydrogen bond via water molecules restricting the attachment point in the pyrazole scaffold. The quantum mechanics calculation of the newly determined ALK2 (R206H) RK-71807 complex structure using a fragment molecular orbital method and pair interaction energy decomposition analysis was employed to evaluate the interaction energies between the inhibitor and each of the amino acid residues and decompose them to electrostatic, exchange-repulsion, and charge transfer energies. The pattern of decomposed interaction energies was then compared to that formed by RK-59638 and LDN-193189 to investigate the structural basis of ALK2 (R206H) inhibition.

Bis-Heteroaryl Pyrazoles: Identification of Orally Bioavailable Inhibitors of Activin Receptor-Like Kinase-2 (R206H).

Mutant activin receptor-like kinase-2 (ALK2) was reported to be closely associated with the pathogenesis of fibrodysplasia ossificans progressiva (FOP) and diffuse intrinsic pontine glioma (DIPG), and therefore presents an attractive target for therapeutic intervention. Through in silico virtual screenings and structure-activity relationship studies assisted by X-ray crystallographic analyses, a novel series of bis-heteroaryl pyrazole was identified as potent inhibitors of ALK2 (R206H). Derived from in silico hit compound RK-59638 (6a), compound 18p was identified as a potent inhibitor of ALK2 (R206H) with good aqueous solubility, liver microsomal stability, and oral bioavailability.

Crystal structure of human nucleosome core particle containing enzymatically introduced CpG methylation.

Cytosine methylation, predominantly of the CpG sequence in vertebrates, is one of the major epigenetic modifications crucially involved in the control of gene expression. Due to the difficulty of reconstituting site-specifically methylated nucleosomal DNA at crystallization quality, most structural analyses of CpG methylation have been performed using chemically synthesized oligonucleotides, There has been just one recent study of nucleosome core particles (NCPs) reconstituted with nonpalindromic human satellite 2-derived DNAs. Through the preparation of a 146-bp palindromic α-satellite-based nucleosomal DNA containing four CpG dinucleotide sequences and its enzymatic methylation and restriction, we reconstituted a 'symmetric' human CpG-methylated nucleosome core particle (NCP). We solved the crystal structures of the CpG-methylated and unmodified NCPs at 2.6 and 3.0 Å resolution, respectively. We observed the electron densities of two methyl groups, among the eight 5-methylcytosines introduced in the CpG-fully methylated NCP. There were no obvious structural differences between the CpG-methylated 'symmetric NCP' and the unmodified NCP. The preparation of a crystallization-grade CpG-methylated NCP provides a platform for the analysis of CpG-methyl reader and eraser proteins.

Intra- and inter-nucleosomal interactions of the histone H4 tail revealed with a human nucleosome core particle with genetically-incorporated H4 tetra-acetylation.

Post-translational modifications (PTMs) of histones, such as lysine acetylation of the N-terminal tails, play crucial roles in controlling gene expression. Due to the difficulty in reconstituting site-specifically acetylated nucleosomes with crystallization quality, structural analyses of histone acetylation are currently performed using synthesized tail peptides. Through engineering of the genetic code, translation termination, and cell-free protein synthesis, we reconstituted human H4-mono- to tetra-acetylated nucleosome core particles (NCPs), and solved the crystal structures of the H4-K5/K8/K12/K16-tetra-acetylated NCP and unmodified NCP at 2.4 Å and 2.2 Å resolutions, respectively. The structure of the H4-tetra-acetylated NCP resembled that of the unmodified NCP, and the DNA wrapped the histone octamer as precisely as in the unmodified NCP. However, the B-factors were significantly increased for the peripheral DNAs near the N-terminal tail of the intra- or inter-nucleosomal H4. In contrast, the B-factors were negligibly affected by the H4 tetra-acetylation in histone core residues, including those composing the acidic patch, and at H4-R23, which interacts with the acidic patch of the neighboring NCP. The present study revealed that the H4 tetra-acetylation impairs NCP self-association by changing the interactions of the H4 tail with DNA, and is the first demonstration of crystallization quality NCPs reconstituted with genuine PTMs.