Effect of Probiotics in Stress-Associated Constipation Model in Zebrafish (Danio rerio) Larvae.

The pathophysiology of functional bowel disorders is complex, involving disruptions in gut motility, visceral hypersensitivity, gut-brain-microbiota interactions, and psychosocial factors. Light pollution, as an environmental stressor, has been associated with disruptions in circadian rhythms and the aggravation of stress-related conditions. In this study, we investigated the effects of environmental stress, particularly continuous light exposure, on intestinal motility and inflammation using zebrafish larvae as a model system. We also evaluated the efficacy of probiotics, specifically Bifidobacterium longum (B. longum), at alleviating stress-induced constipation. Our results showed that continuous light exposure in zebrafish larvae increased the cortisol levels and reduced the intestinal motility, establishing a stress-induced-constipation model. We observed increased inflammatory markers and decreased intestinal neural activity in response to stress. Furthermore, the expressions of aquaporins and vasoactive intestinal peptide, crucial for regulating water transport and intestinal motility, were altered in the light-induced constipation model. Administration of probiotics, specifically B. longum, ameliorated the stress-induced constipation by reducing the cortisol levels, modulating the intestinal inflammation, and restoring the intestinal motility and neural activity. These findings highlight the potential of probiotics to modulate the gut-brain axis and alleviate stress-induced constipation. Therefore, this study provides a valuable understanding of the complex interplay among environmental stressors, gut function, and potential therapeutic strategies.

Interleukin-10 Knockout Mice Do Not Reliably Exhibit Macroscopic Inflammation: A Natural History Endoscopic Surveillance Study.

BACKGROUND: Interleukin (IL)-10 knockout (KO) mice, a model for inflammatory bowel disease (IBD), develop chronic enterocolitis due to an aberrant immune response to enteric antigens. Endoscopy, the gold standard for evaluation of human mucosal health, is not widely available for murine models. AIMS: To assess the natural history of left-sided colitis in IL-10 KO mice via serial endoscopies. METHODS: BALB/cJ IL-10 KO mice underwent regular endoscopic assessments from 2 up to 8 months of age. Procedures were recorded and blindly evaluated using a 4-component endoscopic score: mucosal wall transparency, intestinal bleeding, focal lesions and perianal lesions (0-3 points each). An endoscopic score ≥ 1 point was considered as the presence of colitis/flare. RESULTS: IL-10 KO mice (N = 40, 9 female) were assessed. Mean age at first endoscopy was 62.5 ± 2.5 days; average number of procedures per mouse was 6.0 ± 1.3. A total of 238 endoscopies were conducted every 24.8 ± 8.3 days, corresponding to 124.1 ± 45.2 days of surveillance per mouse. Thirty-three endoscopies in 24 mice (60%) detected colitis, mean endoscopy score 2.5 ± 1.3 (range: 1-6.3). Nineteen mice (47.5%) had one episode of colitis and 5 (12.5%) had 2-3 episodes. All exhibited complete spontaneous healing on subsequent endoscopies. CONCLUSIONS: In this large-scale endoscopic surveillance study of IL-10 KO mice, 40% of mice did not develop endoscopic left-sided colitis. Furthermore, IL-10 KO mice did not exhibit persistent colitis and universally exhibited complete spontaneous healing without treatment. The natural history of colitis in IL-10 KO mice may not be comparable with that of IBD in humans and requires careful consideration.

Assessment of novel ICT-EMS systems to improve emergency patient transportation during the COVID-19 pandemic.

OBJECTIVES: This study aimed to examine the usability, feasibility, acceptability, and appropriateness of the information and communication technology for emergency medical services (ICT-EMS) systems to improve the transportation of emergency patients during the COVID-19 pandemic. METHODS: Emergency medical technicians (EMTs) (n = 229) employed at 7 fire stations operated by the North Chungcheong Fire Service Headquarters, South Korea were trained to use ICT-EMS devices prior to a 1-month implementation period. System Usability Scale (SUS), Feasibility of Intervention Measure (FIM), Acceptability of Intervention Measure (AIM), and Intervention Appropriateness Measure (IAM) questionnaires were conducted in the 4th week of the 1-month implementation period to assess the perceived usability, feasibility, acceptability, and appropriateness of the ICT-EMS systems. RESULTS: Among a total of 229 EMTs, 187 EMTs (81.7%) completed the survey. The overall SUS score was significantly low (score of 35.6) indicating an overall negative perception of the ICT-EMS systems. With regard to the feasibility, acceptability, and intervention appropriateness of ICT-EMS, roughly 50 (26.7%) participants agreed that ICT-EMS implementation was possible, appealing, and suitable. CONCLUSION: Many potential areas of improvement were identified within the ICT-EMS systems. System alterations regarding usability, feasibility, acceptability, and appropriateness may be necessary to successfully implement the ICT-EMS systems.

Dimethyl Itaconate Reduces α-MSH-Induced Pigmentation via Modulation of AKT and p38 MAPK Signaling Pathways in B16F10 Mouse Melanoma Cells.

Dimethyl itaconate (DMI) exhibits an anti-inflammatory effect. Activation of nuclear factor erythroid 2-related factor 2 (NRF2) is implicated in the inhibition of melanogenesis. Therefore, DMI and itaconic acid (ITA), classified as NRF2 activators, have potential uses in hyperpigmentation reduction. The activity of cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB), an important transcription factor for MITF gene promoter, is regulated by glycogen synthase kinase 3ß (GSK3ß) and protein kinase A (PKA). Here, we investigated the inhibitory effect of ITA and DMI on alpha-melanocyte-stimulating hormone (α-MSH)-induced MITF expression and the modulatory role of protein kinase B (AKT) and GSK3ß in melanogenesis in B16F10 mouse melanoma cells. These cells were incubated with α-MSH alone or in combination with ITA or DMI. Proteins were visualized and quantified using immunoblotting and densitometry. Compared to ITA, DMI treatment exhibited a better inhibitory effect on the α-MSH-induced expression of melanogenic proteins such as MITF. Our data indicate that DMI exerts its anti-melanogenic effect via modulation of the p38 mitogen-activated protein kinase (MAPK) and AKT signaling pathways. In conclusion, DMI may be an effective therapeutic agent for both inflammation and hyperpigmentation.

Incidence and risk factors for postoperative common bile duct stones in patients undergoing endoscopic extraction and subsequent cholecystectomy.

BACKGROUND AND AIMS: In patients who undergo cholecystectomy after endoscopic common bile duct (CBD) stone extraction, CBD stones found postoperatively could be problematic. This study aimed to investigate the incidence and risk factors of postoperative CBD stones after cholecystectomy. METHODS: A total of 278 patients (mean age, 59.2 years; 71 men [51.1%]) who underwent endoscopic removal of CBD stones followed by cholecystectomy from January 2013 to December 2017 were included. An endoscopic nasobiliary drainage (ENBD) tube was placed immediately after endoscopic clearance of the CBD stones in all patients until cholecystectomy. An ENBD tubogram was obtained in all patients to determine the presence of postoperative CBD stones. RESULTS: Postoperative CBD stones were detected in 20.1% (56/278). An ENBD tubogram was obtained after an average of 2.42 days postoperatively. Based on univariate analysis, the statistically significant risk factors for postoperative CBD stone were CBD stones >2, CBD stone size >10 mm, cholesterol stone, maximum diameter of CBD >15 mm, treatment with endoscopic sphincterotomy alone, and use of endoscopic mechanical lithotripsy (EML). In multivariate analysis, cholesterol stone, CBD stones >2, CBD stone size >10 mm, and EML were related to postoperative CBD stones after cholecystectomy. CONCLUSIONS: Based on the relatively high rate of postoperative CBD stones after cholecystectomy, careful follow-up should be considered in patients with high-risk factors to detect CBD stones early.

Prunetin 4'-O-Phosphate, a Novel Compound, in RAW 264.7 Macrophages Exerts Anti-Inflammatory Activity via Suppression of MAP Kinases and the NFκB Pathway.

Biorenovation, a microbial enzyme-assisted degradation process of precursor compounds, is an effective approach to unraveling the potential bioactive properties of the derived compounds. In this study, we obtained a new compound, prunetin 4'-O-phosphate (P4P), through the biorenovation of prunetin (PRN), and investigated its anti-inflammatory effects in lipopolysaccharide (LPS)-treated RAW 264.7 macrophage cells. The anti-inflammatory effect of P4P was evaluated by measuring the production of prostaglandin-E2 (PGE2), nitric oxide (NO), which is an inflammation-inducing factor, and related cytokines such as tumor necrosis factor-α (TNFα), interleukin-1ß (IL1ß), and interleukin-6 (IL6). The findings demonstrated that P4P was non-toxic to cells, and its inhibition of the secretion of NO-as well as pro-inflammatory cytokines-was concentration-dependent. A simultaneous reduction in the protein expression level of pro-inflammatory proteins such as cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) was observed. Moreover, the phosphorylation of mitogen-activated protein kinases (MAPKs) such as extracellular signal-regulated kinases (ERKs), c-Jun N-terminal kinase (JNK), p38 MAPK (p38), and nuclear factor kappa B (NFκB) was downregulated. To conclude, we report that biorenovation-based phosphorylation of PRN improved its anti-inflammatory activity. Cell-based in vitro assays further confirmed that P4P could be applied in the development of anti-inflammatory therapeutics.

Luteolin-3'-O-Phosphate Inhibits Lipopolysaccharide-Induced Inflammatory Responses by Regulating NF-κB/MAPK Cascade Signaling in RAW 264.7 Cells.

Luteolin (LT), present in most plants, has potent anti-inflammatory properties both in vitro and in vivo. Furthermore, some of its derivatives, such as luteolin-7-O-glucoside, also exhibit anti-inflammatory activity. However, the molecular mechanisms underlying luteolin-3'-O-phosphate (LTP)-mediated immune regulation are not fully understood. In this paper, we compared the anti-inflammatory properties of LT and LTP and analyzed their molecular mechanisms of action; we obtained LTP via the biorenovation of LT. We investigated the anti-inflammatory activities of LT and LTP in macrophage RAW 264.7 cells. We confirmed from previously reported literature that LT inhibits the production of nitric oxide and prostaglandin E2, as well as the expression of inducible NO synthetase and cyclooxygenase-2. In addition, expressions of inflammatory genes and mediators, such as tumor necrosis factor-α, interleukin-6, and interleukin-1ß, were suppressed. LTP showed anti-inflammatory activity similar to LT, but better anti-inflammatory activity in all the experiments, while also inhibiting mitogen-activated protein kinase and nuclear factor-kappa B more effectively than LT. At a concentration of 10 µM, LTP showed differences of 2.1 to 44.5% in the activity compared to LT; it also showed higher anti-inflammatory activity. Our findings suggest that LTP has stronger anti-inflammatory activity than LT.

7-Acetoxycoumarin Inhibits LPS-Induced Inflammatory Cytokine Synthesis by IκBα Degradation and MAPK Activation in Macrophage Cells.

Acetylation involves the chemical introduction of an acetyl group in place of an active hydrogen group into a compound. In this study, we synthesized 7-acetoxycoumarin (7AC) from acetylation of umbelliferone (UMB). We examined the anti-inflammatory properties of 7AC in lipopolysaccharide (LPS)-treated RAW 264.7 macrophage cells. The anti-inflammatory activity of 7AC on viability of treated cells was assessed by measuring the level of expression of NO, PGE2 and pro-inflammatory cytokines, namely interleukin-1ß (IL-1ß), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in 7AC-treated RAW 264.7 macrophages. The 7AC was nontoxic to cells and inhibited the production of cytokines in a concentration-dependent manner. In addition, its treatment suppressed the production of pro-inflammatory cytokines in a dose-dependent manner and concomitantly decreased the protein and mRNA expressions of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2). Moreover, the levels of the phosphorylation of mitogen-activated protein kinase (MAPK) family proteins such as extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38 and nuclear factor kappa B (NF-κB) were reduced by 7AC. In conclusion, we generated an anti-inflammatory compound through acetylation and demonstrated its efficacy in cell-based in vitro assays.

Prognostic assessment using a new substaging system for Barcelona clinic liver cancer stage C hepatocellular carcinoma: A nationwide study.

AIM & BACKGROUND: Advanced hepatocellular carcinoma (HCC) (Barcelona clinic liver cancer [BCLC] stage C) needs subclassification to more accurately predict survival. This study aims to establish a substaging system of BCLC stage C HCC patients for accurate prognosis. METHODS: Data from 564 patients with newly diagnosed BCLC stage C HCC from three tertiary-care hospitals affiliated with the Korea University (training set) were assessed retrospectively. Variables affecting overall survival (OS) were analysed, and patients were substaged according to the number of prognostic factors they fulfilled. The substaging system was validated using a nationwide database from the Korean Liver Cancer Association (validation set; n = 742). RESULTS: In the training set, tumour factors such as tumour burden ≥10 cm, major portal vein invasion and distant metastasis, as well as underlying liver function, were independently associated with OS. BCLC stage C was classified into four substages (C1-4) according to the number of prognostic factors. Substages C1, C2, C3 and C4 showed a median OS of 17.50 months (95% confidence interval [CI], 8.57-26.43), 10.13 months (95% CI, 8.17-12.09), 4.20 months (95% CI, 3.42-4.98), and 2.90 months (95% CI, 2.34-3.46) respectively (P < 0.05). This substaging system also had good discriminative ability in predicting survival in the validation set. In addition, it was considered that the BCLC substaging is better than Hong Kong liver cancer substaging in predicting the OS for patients with advanced HCC. CONCLUSION: Our substaging for BCLC stage C might help predict patients' prognosis better.

Nationwide antibiotic resistance mapping of Helicobacter pylori in Korea: A prospective multicenter study.

INTRODUCTION: The eradication rates for Helicobacter pylori have decreased in Korea although the prevalence of this bacterium has also decreased. Antibiotic resistance is likely to be a crucial factor in H. pylori eradication success, and we therefore mapped these resistance patterns nationwide in Korea. MATERIALS AND METHODS: Five hundred and ninety adult subjects were prospectively enrolled from 2017 to 2018 from 15 centers across six geographic areas of Korea. A total of 580 biopsy tissues had been sampled from these patients during an upper endoscopy and were frozen at -80°C and delivered to a central laboratory. The agar dilution method was used to determine the minimum inhibitory concentration of amoxicillin, clarithromycin, metronidazole, tetracycline, ciprofloxacin, and levofloxacin for each H. pylori isolate. RESULTS: The culture success rate was 60.2% (349/580). Resistance rates against clarithromycin, metronidazole, amoxicillin, tetracycline, levofloxacin, and ciprofloxacin were 17.8%, 29.5%, 9.5%, 0%, 37.0%, and 37.0%, respectively. The geographic distribution of metronidazole and quinolone resistance was highly variable. Some subjects had multiple H. pylori strains in the antrum and body of the stomach and showed a heterogeneous resistance profile between these anatomic areas. The H. pylori multidrug resistance (MDR) rate was 25.2% (88/349) among amoxicillin, clarithromycin, metronidazole, tetracycline, and quinolone and 11.2% (39/349) among four of these major antibiotics except for quinolone. The Seoul and Chungcheong areas showed a relatively lower MDR rate. CONCLUSION: The antibiotic resistance of H. pylori differs by drug and geographic area in Korea. Detailed nationwide antibiotic resistance mapping is needed to develop an effective H. pylori eradication strategy.

Anti-Inflammatory Effects of Formononetin 7-O-phosphate, a Novel Biorenovation Product, on LPS-Stimulated RAW 264.7 Macrophage Cells.

Biorenovation is a microbial enzyme-catalyzed structural modification of organic compounds with the potential benefits of reduced toxicity and improved biological properties relative to their precursor compounds. In this study, we synthesized a novel compound verified as formononetin 7-O-phosphate (FMP) from formononetin (FM) using microbial biotransformation. We further compared the anti-inflammatory properties of FMP to FM in lipopolysaccharide (LPS)-treated RAW264.7 macrophage cells. We observed that cell viabilities and inhibitory effects on LPS-induced nitric oxide (NO) production were greater in FMP-treated RAW 264.7 cells than in their FM-treated counterparts. In addition, FMP treatment suppressed the production of proinflammatory cytokines such as prostaglandin-E2 (PGE2), interleukin-6 (IL-6), and interleukin-1ß (IL-1ß) in a dose-dependent manner and concomitantly decreased the mRNA expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2). We also found that FMP exerted its anti-inflammatory effects through the downregulation of the extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and nuclear factor kappa B (NF-κB) signaling pathways. In conclusion, we generated a novel anti-inflammatory compound using biorenovation and demonstrated its efficacy in cell-based in vitro assays.

8-Methoxycoumarin enhances melanogenesis via the MAPKase signaling pathway.

8-Methoxycoumarin (8-methoxy-chromen-2-one), isolated from R. graveolens L., is able to alleviate arthritis by inhibition of proinflammatory cytokines. However, its effects on melanogenesis have largely remained unreported. The present study examined the effects of 8-methoxycoumarin on melanogenesis in B16F10 murine cells, together with its effect on the mechanism of melanin synthesis. The cells were treated with different concentrations of 8-methoxycoumarin; α-MSH was used as the positive control. We found 8-methoxycoumarin to significantly increase the melanin content of the cells without exerting any cytotoxicity. In addition, it significantly upregulated the expression of tyrosinase and tyrosinase-related protein-1 and 2 via inducing the expression of microphthalmia-associated transcription factor. Furthermore, we demonstrated the involvement of mitogen-activated protein kinase (MAPK) pathway-mediated phosphorylation of p38 and c-Jun N-terminal kinase (JNK), and inhibition of phosphorylation of extracellular signal-regulated kinase (ERK) to be responsible for enhanced melanin production. Use of SB203580 (p38 inhibitor) and SP600125 (p-JNK inhibitor) corroborated these findings. Additionally, we investigated the effects of 8-methoxycoumarin on protein kinase B (AKT) phosphorylation and protein kinase A (PKA) signaling pathway (using H89, a PKA inhibitor). These results suggested that 8-methoxycoumarin increases melanogenesis via the MAPK signaling pathway. Based on these findings, we conclude that 8-methoxycoumarin could serve as a potential compound for treating hypopigmentation disorders. It could also serve as a promising chemical for hair depigmentation treatment in the cosmetic industry.

Biochemical and Structural Analysis of FomD That Catalyzes the Hydrolysis of Cytidylyl ( S)-2-Hydroxypropylphosphonate in Fosfomycin Biosynthesis.

In fosfomycin biosynthesis, the hydrolysis of cytidylyl ( S)-2-hydroxypropylphosphonate [( S)-HPP-CMP] to afford ( S)-HPP is the only uncharacterized step. Because FomD is an uncharacterized protein with a DUF402 domain that is encoded in the fosfomycin biosynthetic gene cluster, FomD was hypothesized to be responsible for this reaction. In this study, FomD was found to hydrolyze ( S)-HPP-CMP to give ( S)-HPP and CMP efficiently in the presence of Mn2+ or Co2+. FomD also hydrolyzed cytidylyl 2-hydroxyethylphosphonate (HEP-CMP), which is a biosynthetic intermediate before C-methylation. The kcat/ KM value of FomD with ( S)-HPP-CMP was 10-fold greater than that with HEP-CMP, suggesting that FomD hydrolyzes ( S)-HPP-CMP rather than HEP-CMP in bacteria. The crystal structure of FomD showed that this protein adopts a barrel-like fold, which consists of a large twisted antiparallel ß-sheet. This is a key structural feature of the DUF402 domain-containing proteins. Two metal cations are located between the FomD barrel and the two α-helices at the C-terminus and serve to presumably activate the phosphonate group of substrates for hydrolysis. Docking simulations with ( S)-HPP-CMP suggested that the methyl group at the C2 position of the HPP moiety is recognized by a hydrophobic interaction with Trp68. Further mutational analysis suggested that a conserved Tyr107 among the DUF402 domain family of proteins activates a water molecule to promote nucleophilic attack on the phosphorus atom of the phosphonate moiety. These findings provide mechanistic insights into the FomD reaction and lead to a complete understanding of the fosfomycin biosynthetic pathway in Streptomyces.

Bacterial Enzymes Catalyzing the Synthesis of 1,8-Dihydroxynaphthalene, a Key Precursor of Dihydroxynaphthalene Melanin, from Sorangium cellulosum.

1,8-Dihydroxynaphthalene (1,8-DHN) is a key intermediate in the biosynthesis of DHN melanin, which is specific to fungi. In this study, we characterized the enzymatic properties of the gene products of an operon consisting of soceCHS1, bdsA, and bdsB from the Gram-negative bacterium Sorangium cellulosum Heterologous expression of soceCHS1, bdsA, and bdsB in Streptomyces coelicolor caused secretion of a dark-brown pigment into the broth. High-performance liquid chromatography (HPLC) analysis of the broth revealed that the recombinant strain produced 1,8-DHN, indicating that the operon encoded a novel enzymatic system for the synthesis of 1,8-DHN. Simultaneous incubation of the recombinant SoceCHS1, BdsA, and BdsB with malonyl-coenzyme A (malonyl-CoA) and NADPH resulted in the synthesis of 1,8-DHN. SoceCHS1, a type III polyketide synthase (PKS), catalyzed the synthesis of 1,3,6,8-tetrahydroxynaphthalene (T4HN) in vitro T4HN was in turn converted to 1,8-DHN by successive steps of reduction and dehydration, which were catalyzed by BdsA and BdsB. BdsA, which is a member of the aldo-keto reductase (AKR) superfamily, catalyzed the reduction of T4HN and 1,3,8-tetrahydroxynaphthalene (T3HN) to scytalone and vermelone, respectively. The stereoselectivity of T4HN reduction by BdsA occurred on the si-face to give (R)-scytalone with more than 99% optical purity. BdsB, a SnoaL2-like protein, catalyzed the dehydration of scytalone and vermelone to T3HN and 1,8-DHN, respectively. The fungal pathway for the synthesis of 1,8-DHN is composed of a type I PKS, naphthol reductases of the short-chain dehydrogenase/reductase (SDR) superfamily, and scytalone dehydratase (SD). These findings demonstrated 1,8-DHN synthesis by novel enzymes of bacterial origin.IMPORTANCE Although the DHN biosynthetic pathway was thought to be specific to fungi, we discovered novel DHN synthesis enzymes of bacterial origin. The biosynthesis of bacterial DHN utilized a type III PKS for polyketide synthesis, an AKR superfamily for reduction, and a SnoaL2-like NTF2 superfamily for dehydration, whereas the biosynthesis of fungal DHN utilized a type I PKS, SDR superfamily enzyme, and SD-like NTF2 superfamily. Surprisingly, the enzyme systems comprising the pathway were significantly different from each other, suggesting independent, parallel evolution leading to the same biosynthesis. DHN melanin plays roles in host invasion and adaptation to stress in pathogenic fungi and is therefore important to study. However, it is unclear whether DHN biosynthesis occurs in bacteria. Importantly, we did find that bacterial DHN biosynthetic enzymes were conserved among pathogenic bacteria.

Comparative study of Helicobacter pylori eradication rates of concomitant therapy vs modified quadruple therapy comprising proton-pump inhibitor, bismuth, amoxicillin, and metronidazole in Korea.

BACKGROUND: The standard triple Helicobacter pylori regimen now shows unacceptably low treatment success in Korea. Administration of the concomitant therapy for 10 days, which has a high cure rate, is recommended as an alternative first-line treatment in areas of high clarithromycin resistance including Korea. Recently, modified bismuth-containing quadruple therapy with amoxicillin (PAM-B therapy) showed excellent results, regardless of dual clarithromycin and metronidazole resistance. This study compared the concomitant therapy with PAM-B therapy as a first-line treatment for H. pylori infection. METHOD: Subjects infected with H. pylori and naïve to treatment were performed a head-to-head comparison between 10-day concomitant therapy [rabeprazole 20 mg, amoxicillin 1 g, clarithromycin 500 mg, and metronidazole 500 mg twice daily] and 14-day PAM-B therapy [rabeprazole 20 mg, amoxicillin 1 g, metronidazole 750 mg, and tripotassium dicitrato bismuthate 600 mg (elemental bismuth 240 mg) twice daily]. Six weeks after treatment, H. pylori eradication was assessed. RESULTS: Two hundred and seventy subjects were randomized. Both regimens achieved high cure rates: 83.0% (112/135) and 88.1% (119/135) by the intention-to-treat analysis and 95.5% (106/111) and 96.6% (114/118) by the per-protocol analysis, respectively. The intention-to-treat and per-protocol analyses revealed no statistically significant difference in the eradication rate (P = .299 and P = .743, respectively). Rates of adverse events were similar between groups (25.2% vs 23.0%, P -value: .776) Adverse events, which resulted in poor compliance, occurred in six patients of each group, but there were no serious complications. CONCLUSIONS: PAM-B therapy is as effective as concomitant therapy for eradicating H. pylori with comparative safety. PAM-B therapy is regarded as a promising alternative to standard triple therapy for a first-line eradication in Korea.

Methylcobalamin-Dependent Radical SAM C-Methyltransferase Fom3 Recognizes Cytidylyl-2-hydroxyethylphosphonate and Catalyzes the Nonstereoselective C-Methylation in Fosfomycin Biosynthesis.

A methylcobalamin (MeCbl)-dependent radical S-adenosyl-l-methionine (SAM) methyltransferase Fom3 was found to catalyze the C-methylation of cytidylyl-2-hydroxyethylphosphonate (HEP-CMP) to give cytidylyl-2-hydroxypropylphosphonate (HPP-CMP), although it was originally proposed to catalyze the C-methylation of 2-hydroxyethylphosphonate to give 2-hydroxypropylphosphonate in the biosynthesis of a unique C-P bond containing antibiotic fosfomycin in Streptomyces. Unexpectedly, the Fom3 reaction product from HEP-CMP was almost a 1:1 diastereomeric mixture of HPP-CMP, indicating that the C-methylation is not stereoselective. Presumably, only the CMP moiety of HEP-CMP is critical for substrate recognition; on the other hand, the enzyme does not fix the 2-hydroxy group of the substrate and either of the prochiral hydrogen atoms at the C2 position can be abstracted by the 5'-deoxyadenosyl radical generated from SAM to form the substrate radical intermediates, which react with MeCbl to afford the corresponding products. This strict substrate recognition mechanism with no stereoselectivity of a MeCbl-dependent radical SAM methyltransferase is remarkable in natural product biosynthetic chemistry, because such a hidden clue for selective substrate recognition is likely to be found in the other biosynthetic pathways.

Helicobacter pylori eradication rates of concomitant and sequential therapies in Korea.

BACKGROUND: The efficacy of the standard triple therapy for Helicobacter pylori eradication has decreased to an unacceptable level. We aimed to compare the efficacy of sequential and concomitant therapies as for the first-line treatments for H. pylori eradication and analyzed the effect of clarithromycin resistance on the eradication rates. MATERIALS AND METHODS: Four hundred and seventy-eight patients with H. pylori infection were randomly assigned to either concomitant therapy (amoxicillin 1000 mg with clarithromycin 500 mg, metronidazole 500 mg, and pantoprazole 40 mg twice daily for 10 days) or sequential therapy (amoxicillin 1000 mg with pantoprazole 40 mg twice daily for 5 days, followed by clarithromycin 500 mg with metronidazole 500 mg and pantoprazole 40 mg twice daily for 5 days). The success of the eradication was evaluated 4-5 weeks after treatment completion. To evaluate the efficacy of the two regimens according to clarithromycin sensitivity, dual-priming oligonucleotide-based multiplex-polymerase chain reaction was also performed in the final third of the enrolled study populations. RESULTS: The eradication rates with concomitant or sequential therapy were 81.9% and 76.6% (P = .153) in intention-to-treat analysis, and 93.4% and 84.8% (P = .004) in per-protocol analysis, respectively. Among the 156 patients for whom dual-priming oligonucleotide-based multiplex-polymerase chain reaction was performed, 17.9% were clarithromycin resistant, and the efficacy of concomitant therapy was better than sequential therapy in the clarithromycin-resistant strains (100% vs 58.3%, P = .010). CONCLUSION: Concomitant therapy was superior to sequential therapy as the first-line treatment for H. pylori eradication, especially in clarithromycin-resistant strains in Korea.

Endoscopic biliary stent insertion through specialized duodenal stent for combined malignant biliary and duodenal obstruction facilitated by stent or PTBD guidance.

OBJECTIVES: Endoscopic stenting for combined malignant biliary and duodenal obstruction is technically demanding. However, this procedure can be facilitated when there is guidance from previously inserted stent or PTBD tube. This study aimed to evaluate the feasibility and clinical success rate of endoscopic placement of biliary self-expandable metal stent (SEMS) through duodenal SEMS in patients with combined biliary and duodenal obstruction due to inoperable or metastatic periampullary malignancy. MATERIALS AND METHODS: A total of 12 patients with combined malignant biliary and duodenal stricture underwent insertion of biliary SEMS through the mesh of specialized duodenal SEMS from July 2012 to October 2016. Technical and clinical success rate, adverse events and survival after completion of SEMS insertion were evaluated. RESULTS: The duodenal strictures were located in the first portion of the duodenum in four patients (Type I), in the second portion in three patients (Type II), and in the third portion in five patients (Type III). Technical success rate of combined metallic stenting was 91.7%. Insertion of biliary SEMS was guided by previously inserted biliary SEMS in nine patients, plastic stent in one patient, and PTBD in two patients. Clinical success rate was 90.9%. There were no early adverse events after the procedure. Mean survival period after combined metallic stenting was 91.9 days (range: 15-245 days). CONCLUSIONS: Endoscopic placement of biliary SEMS through duodenal SEMS is feasible with high success rates and relatively easy when there is guidance. This method can be a good alternative for palliation in patients with combined biliary and duodenal obstruction.

Standard and double-dose intravenous proton pump inhibitor injections for prevention of bleeding after endoscopic resection.

BACKGROUND AND AIM: Endoscopic resection is commonly used to remove gastric neoplasms. However, effective dosing or scheduling of proton pump inhibitors for the prevention of delayed bleeding after endoscopic resection remains unclear. METHODS: One hundred sixty-six patients with gastric adenoma or early gastric cancer were enrolled. After an endoscopic procedure, each subject was randomly assigned to 40 mg every 24 h (standard dose group) or 40 mg every 12 h (double-dose group) of intravenous pantoprazole for 48 h. Second-look endoscopy was performed on day 2 after endoscopic resection to compare signs of rebleeding and ulcer status between the two groups. RESULT: Eighty-one patients of the standard dose group and 81 of the double-dose group were analyzed. There were no significant differences in the incidence of delayed bleeding events (1.3% vs 6.2%, P = 0.21) and bleeding ulcer at the second-look endoscopy (6.2% vs 3.9%, P = 0.69) between standard and double-dose groups. There were no other significant variables associated with delayed bleeding or bleeding ulcer on second-look endoscopy. CONCLUSIONS: Intravenous pantoprazole 40 mg every 24 h or 12 h for 2 days after endoscopic resection was equally effective for the prevention of delayed bleeding.

Risk of Vascular Thrombotic Events Following Discontinuation of Antithrombotics After Peptic Ulcer Bleeding.

GOALS: To evaluate whether the risk of cardiovascular events increases when antithrombotics are discontinued after ulcer bleeding. BACKGROUND: Peptic ulcer bleeding associated with antithrombotics has increased due to the increase in the proportion of elderly population. Little is known about the long-term effects of discontinuing antithrombotics after peptic ulcer bleeding. The aim of this study was to evaluate whether the risk of cardiovascular events increases when antithrombotics are discontinued after ulcer bleeding. STUDY: We reviewed the medical records of patients with ulcer bleeding who were taking antiplatelet agents or anticoagulants at the time of ulcer bleeding. Cox-regression model was used to adjust for potential confounders, and analyzed association between discontinuation of antithrombotic drugs after ulcer bleeding and thrombotic events such as ischemic heart disease or stroke. RESULTS: Of the 544 patients with ulcer bleeding, 72 patients who were taking antithrombotics and followed up for >2 months were analyzed. Forty patients discontinued antithrombotics after ulcer bleeding (discontinuation group) and 32 patients continued antithrombotics with or without transient interruption (continuation group). Thrombotic events developed more often in discontinuation group than in the continuation group [7/32 (21.9%) vs. 1/40 (2.5%), P=0.019]. Hazard ratio for thrombotic event when antithrombotics were continuously discontinued was 10.9 (95% confidence interval, 1.3-89.7). There were no significant differences in recurrent bleeding events between the 2 groups. CONCLUSIONS: Discontinuation of antithrombotics after peptic ulcer bleeding increases the risk of cardiovascular events. Therefore, caution should be taken when discontinuing antithrombotics after ulcer bleeding.