Relationship between Chemotherapy-Induced Diarrhea and Intestinal Microbiome Composition.

BACKGROUND AND AIM: Fluoropyrimidines (FPs) are key drugs in many chemotherapy regimens; however, recipients are often prone to diarrhea due to gastrointestinal toxicity. Disruption of the intestinal epithelial barrier function by FPs leads to dysbiosis, which may exacerbate intestinal epithelial cell damage as a secondary effect and trigger diarrhea. However, despite studies on chemotherapy-induced changes in the intestinal microbiome of humans, the relationship between dysbiosis and diarrhea is unclear. In this study, we aimed to investigate the relationship between chemotherapy-induced diarrhea and the intestinal microbiome. METHODS: We conducted a single-center prospective observational study. Twenty-three patients who received chemotherapy, including FPs as first-line chemotherapy for colorectal cancer, were included. Stool samples were collected before the start of chemotherapy and after one cycle of treatment to analyze intestinal microbiome composition and perform PICRUSt predictive metagenomic analysis. RESULTS: Gastrointestinal toxicity was observed in 7 of 23 patients (30.4%), diarrhea was observed in 4 (17.4%), and nausea and anorexia were observed in 3 (13.0%). In 19 patients treated with oral FPs, the α diversity of the microbial community decreased significantly following chemotherapy only in the diarrheal group. At the phylum level, the diarrheal group showed a significant decrease in the abundance of Firmicutes and a significant increase in the abundance of Bacteroidetes with chemotherapy (p = 0.013 and 0.011, respectively). In the same groups, at the genus level, Bifidobacterium abundance was significantly decreased (p = 0.019). In contrast, in the non-diarrheal group, Actinobacteria abundance increased significantly with chemotherapy at the phylum level (p = 0.011). Further, Bifidobacterium, Fusicatenibacter, and Dorea abundance significantly increased at the genus level (p = 0.006, 0.019, and 0.011, respectively). The PICRUSt predictive metagenomic analysis revealed that chemotherapy caused significant differences in membrane transport in KEGG pathway level 2 and in 8 KEGG pathway level 3, including transporters and oxidative phosphorylation in the diarrhea group. CONCLUSION: Organic-acid-producing bacteria seem to be involved in diarrhea associated with chemotherapy, including FPs.

Alterations in the gut microbiome in patients with esophageal carcinoma in response to esophagectomy and neoadjuvant treatment.

PURPOSE: Analyzing the gut microbiome is essential for planning treatment strategies to manage esophageal squamous cell carcinoma. This study aimed to characterize the gut microbiome of patients with esophageal squamous cell carcinoma and to identify alterations in its composition during treatment. METHODS: We observed alterations in the gut microbiome in 21 consecutive patients with esophageal squamous cell carcinoma at five different time points, from neoadjuvant treatment to postoperative surgery. Ten healthy individuals were used as a non-cancer control group. Fecal samples were collected and analyzed using 16S ribosomal ribonucleic acid sequencing. RESULTS: Before treatment, participants with esophageal squamous cell carcinoma had different alpha and beta diversity in comparison to healthy controls. The number of Streptococcus, a facultative anaerobic bacterium, was significantly higher, whereas that of Faecalibacterium, an obligate anaerobic bacterium, was significantly lower. Both alpha and beta diversity remained unchanged during neoadjuvant treatment, but the alterations were pronounced after surgery. The increase in the relative abundance of Streptococcus and the decrease in that of Faecalibacterium also tended to be more pronounced after surgery. CONCLUSIONS: The gut microbiome in patients with esophageal squamous cell carcinoma is altered with surgical intervention.

Correction: Improvement of loperamide-induced slow transit constipation by Bifidobacterium bifidum G9-1 is mediated by the correction of butyrate production and neurotransmitter profile due to improvement in dysbiosis.

[This corrects the article DOI: 10.1371/journal.pone.0248584.].

Effect of a High-Fat Diet on the Small-Intestinal Environment and Mucosal Integrity in the Gut-Liver Axis.

Although high-fat diet (HFD)-related dysbiosis is involved in the development of steatohepatitis, its pathophysiology especially in the small intestine remains unclear. We comprehensively investigated not only the liver pathology but also the microbiome profile, mucosal integrity and luminal environment in the small intestine of mice with HFD-induced obesity. C57BL/6J mice were fed either a normal diet or an HFD, and their small-intestinal contents were subjected to microbial 16S rDNA analysis. Intestinal mucosal permeability was evaluated by FITC-dextran assay. The levels of bile acids in the small-intestinal contents were measured by liquid chromatography/mass spectrometry. The expression of tight junction molecules, antimicrobial peptides, lipopolysaccharide and macrophage marker F4/80 in the small intestine and/or liver was examined by real-time RT-PCR and immunohistochemistry. The abundance of Lactobacillus was markedly increased and that of Clostridium was drastically decreased in the small intestine of mice fed the HFD. The level of conjugated taurocholic acid was significantly increased and those of deconjugated cholic acid/secondary bile acids were conversely decreased in the small-intestinal contents. The expression of occludin, antimicrobial Reg IIIß/γ and IL-22 was significantly decreased in the small intestine of HFD-fed mice, and the intestinal permeability was significantly accelerated. Infiltration of lipopolysaccharide was significantly increased in not only the small-intestinal mucosa but also the liver of HFD-fed mice, and fat drops were apparently accumulated in the liver. Pathophysiological alteration of the luminal environment in the small intestine resulting from a HFD is closely associated with minimal inflammation involving the gut-liver axis through disturbance of small-intestinal mucosal integrity.

Improvement of loperamide-induced slow transit constipation by Bifidobacterium bifidum G9-1 is mediated by the correction of butyrate production and neurotransmitter profile due to improvement in dysbiosis.

A treatment option for constipation that improves the quality of life is needed since available laxatives do not effectively improve the quality of life in patients with constipation. A significant association between gut dysbiosis and constipation is recognized, suggesting that probiotics may be an important option for management of constipation. The underlying mechanism by which probiotics improve constipation remains unclear. In this study, we aimed to evaluate the effects of the probiotic Bifidobacterium bifidum G9-1 (BBG9-1) on loperamide-induced delayed colonic transit constipation and to elucidate its mechanism of action. First, the effect of BBG9-1 was evaluated in a rat model of constipation induced by subcutaneous administration of loperamide. BBG9-1 improved constipation parameters (number of feces, fecal water content, and fecal hardness) in constipated rats. Next, the relationship of organic acids and neurotransmitters to gut microbiota was investigated. BBG9-1 improved dysbiosis and prevented a decrease in butyric acid concentration in the gut, increased serum serotonin, and suppressed an increase in dopamine and a decrease in acetylcholine in serum. Further, an increase in the expression level of tryptophan hydroxylase 1, a 5-HT-synthetizing enzyme, was observed. These results suggest that BBG9-1 improves dysbiosis, which results in an increase in organic acids and improvement of neurotransmission. These actions may increase intestinal mobility, finally leading to alleviating constipation. The probiotic BBG9-1 may, therefore, be a potential option for the treatment of constipation.

NOX1/NADPH Oxidase Expressed in Colonic Macrophages Contributes to the Pathogenesis of Colonic Inflammation in Trinitrobenzene Sulfonic Acid-Induced Murine Colitis.

NOX1/NADPH oxidase, a nonphagocytic isoform of reactive oxygen species-producing enzymes, is highly expressed in the colon, but the physiologic and pathophysiologic roles of this isoform are not fully understood. The present study investigated the role of NOX1 in the development of colonic inflammation in a trinitrobenzene sulfonic acid (TNBS)-induced murine colitis model. Intrarectal injection of TNBS caused severe colitis accompanied by body weight loss, diarrhea, and increased myeloperoxidase (MPO) activity in wild-type (WT) mice. In contrast, the severity of colitis was significantly attenuated in NOX1-deficient (NOX1KO) mice (the inhibitions of macroscopic damage score, body weight loss, diarrhea score, and MPO activity were 73.1%, 36.8%, 83.3%, and 98.4%, respectively). TNBS-induced upregulation of inflammatory cytokines (tumor necrosis factor (TNF)-α and interleukin (IL)-1ß), chemokines (CXCL1 and CXLC2), and inducible nitric oxide synthase (iNOS) was also significantly less in NOX1KO than in WT mice (the inhibitions were 100.8%, 89.0%, 63.5%, 96.7%, and 97.1%, respectively). Expression of NOX1 mRNA was detected not only in the lamina propria but also in peritoneal macrophages isolated from WT mice. Increased expression of TNF-α, IL-1ß, and iNOS in peritoneal macrophages exposed to lipopolysaccharide was significantly attenuated in macrophages isolated from NOX1KO mice (68.1%, 67.0%, and 79.3% inhibition, respectively). These findings suggest that NOX1/NADPH oxidase plays an important role in the pathogenesis of TNBS-induced colonic inflammation via upregulation of inflammatory cytokines, chemokines, and iNOS. NOX1 in colonic macrophages may become a potential target in pharmacologic intervention for inflammatory bowel disease.

Challenges to the clinical placement and evaluation of adhesively-bonded, cervical composite restorations.

OBJECTIVES: The incidence of non-carious cervical lesions (NCCLs) has been increasing. The clinical performance of resin composites in NCCLS was previously unsatisfactory due to their non-retentive forms and margins lying on dentin. In order to address this problem, a lot of effort has been put into developing new dentin adhesives and restorative techniques. This article discusses these challenges and the criteria used for evaluating clinical performance as they relate to clinical studies, especially long-term clinical trials. Polymerization contraction, thermal changes and occlusal forces generate debonding stresses at adhesive interfaces. METHODS: In laboratory studies, we have investigated how these stresses can be relieved by various restorative techniques and how bond strength and durability can be enhanced. Lesion forms, restorative techniques, adhesives (adhesive strategies, bond strengths, bond durability, and the relationship between enamel and dentin bond strengths) were found to have a complex relationship with microleakage. With regard to some restorative techniques, only several short-term clinical studies were available. RESULTS: Although in laboratory tests marginal sealing improved with a low-viscosity resin liner, an enamel bevel or prior enamel etching with phosphoric acid, clinical studies failed to detect significant effects associated with these techniques. Long-term clinical trials demonstrated that adhesive bonds continuously degraded in various ways, regardless of the adhesion strategy used. SIGNIFICANCE: Early loss of restoration may no longer be the main clinical problem when reliable adhesives are properly used. Marginal discoloration increased over time and may become a more prominent reason for repair or replacement. Reliable and standardized criteria for the clinical evaluation of marginal discoloration should be established as soon as possible and they should be based on evidence and a policy of minimal intervention.

Three-year clinical evaluation of a flowable and a hybrid resin composite in non-carious cervical lesions.

OBJECTIVES: This randomized controlled clinical trial evaluated the 3-year clinical performance of a hybrid (Clearfil AP-X; AP) and a flowable (Clearfil Flow FX; FX) resin composite in 98 non-carious cervical lesions. METHODS: Twenty-two patients, 11 males and 11 females (mean age: 61.9 years, range: 29-78 years) regularly visiting the Nagasaki University Hospital, participated in the study. Each patient received both materials randomly. All restorations (48 restorations for AP and 50 restorations for FX) were placed in conjunction with an all-in-one system (Clearfil S(3) Bond) by one dentist. The restorations were blindly evaluated by two examiners at baseline, 6 months, 1, 2 and 3 years using modified USPHS criteria. The data were statistically analyzed using the Cochran's Q-test and Fisher's exact test. RESULTS: All the patients were examined at each recall. However, five restorations could not be evaluated at 3-year recall as two teeth had been extracted and three restorations had been lost. The only minor problem was the integrity of the enamel margin. The incidence and extent of marginal staining increased with time, but it was still superficial. Marginal staining occurred adjacent to 11 restorations for AP and 12 restorations for FX after 3 years. Neither lesion size nor depth had influence on marginal staining adjacent to each type of resin composite. There were no significant differences in the clinical performances between AP and FX for each variable. CONCLUSIONS: Under the protocol used in this study, both types of resin composite in conjunction with S(3) Bond demonstrated an acceptable clinical performance up to 3 years.

Two-year clinical evaluation of one-step self-etch systems in non-carious cervical lesions.

OBJECTIVES: This randomized controlled clinical trial evaluated the 2-year clinical performance of S3 Bond (S3) and G-Bond (GB) in 108 non-carious cervical lesions. METHODS: Twenty-three patients, 12 male and 11 female (mean age: 61.8 years, range: 30-79 years) regularly visiting the Nagasaki University Hospital of Medicine and Dentistry, participated in the study. Each patient received both materials randomly. All restorations (53 restorations for S3 and 55 restorations for GB) were placed by one dentist. The restorations were blindly evaluated by two examiners at baseline, 6 months, 1 and 2 years using modified USPHS criteria. The data were statistically analyzed using the Cochran Q test and Fisher's exact test. RESULTS: One restoration of each material was lost during 2 years. The only minor clinical problem was the integrity of the enamel margin. Slight marginal staining occurred adjacent to 11 restorations of both S3 and GB. There was no significant difference in the clinical performance between S3 and GB for each variable. CONCLUSIONS: Under the protocol used in this study, S3 and GB have demonstrated an acceptable clinical performance up to 2 years.

Effect of a caries-detecting solution on the tensile bond strength of four dentin adhesive systems.

This study investigated the effect of a caries-detecting solution on the tensile bond strength (TBS) to sound bovine dentin--which was either rinsed thoroughly of or contaminated with the caries-detecting solution. Caries Detector (1.0% acid red in propylene glycol) was applied on flat dentin surfaces for 10 seconds, rinsed, and dried with syringe air. In another group, Caries Detector was not rinsed but air-dried. Then, the surfaces were treated with one of the following adhesive systems: Clearfil Protect Bond, Clearfil SE Bond, One-Up Bond F, or Single Bond. Furthermore, an ingredient of Caries Detector, either 1.0% acid red aqueous solution or propylene glycol, was applied to evaluate the effect of each component. In the control groups, Caries Detector was not applied to the dentin surfaces. Finally, a resin composite was light-cured and the TBS measured. Fractured specimens and treated dentin surfaces were observed by SEM. Caries Detector did not reduce the tensile bond strength of any adhesive system (p>0.05) when rinsed thoroughly. On the other hand, when dentin surface was contaminated with Caries Detector, TBS decreased significantly with Clearfil SE Bond and Single Bond. As for the ingredients of Caries Detector, the effect of acid red on TBS was not significant, but that of propylene glycol was significant.

Microleakage of cervical cavities restored with flowable composites.

PURPOSE: To investigate the microleakage of cervical cavities restored with flowable composites in conjunction with an all-in-one adhesive system (AQ Bond) and an experimental two-step self-etching primer system (ABF) after thermocycling or flexural load cycling. METHODS: 180 wedge-shaped cervical cavities on the labial surfaces of bovine incisors were treated with AQ Bond or ABF according to the manufacturers' instructions. The treated cavities were filled with one of three flowable composites (AElite Flo, Metafil Flo or Protect Liner F). Ten of 30 specimens for each group were immersed in 0.5% basic fuchsin solution immediately after finishing of the restorations. Specimens to be subjected to thermocycling (5-60 degrees C, 15 seconds dwell time, 5000 cycles) or to flexural load cycling (approximately 0.5 mm labio-lingual displacement at the incisal edge, 10,000 cycles, 1 Hz) prior to immersion in the dye were also prepared. After 24-hour storage in the dye solution, the teeth were sectioned longitudinally through the center of the restorations, and the degrees of dye penetration scored. The microleakage scores of a hybrid composite (Clearfil AP-X) obtained from our previous study were used for comparison. The data were analyzed with the Kruskal-Wallis test and the Mann-Whitney U-test (P < 0.05). RESULTS: No significant differences in the microleakage patterns and scores were found among the flowable composites. On the other hand, significant differences in the microleakage patterns and scores were observed between the flowable and the hybrid composites. Thermocycling caused deterioration of marginal integrity, and the flowable composites showed more microleakage than the hybrid composite. In contrast, flexural load cycling did not cause deterioration of the marginal integrity when the cavities were filled with the flowable composites. Statistical analysis also revealed that the adhesive systems played a large role in the microleakage patterns.

The effect of light-curing modes on the microleakage of cervical resin composite restorations.

OBJECTIVE: This study investigated the effect of light-curing modes on the microleakage of cervical resin composite restorations. METHODS: Eighty wedge-shaped cervical cavities, C-factor approximately 1.3, were prepared on the labial surface of bovine incisors. The cavities were treated with a two-step experimental self-etching primer adhesive system containing an antibacterial monomer (ABF), according to the manufacturer's instructions, and filled with a single increment of a hybrid resin composite. The restorations were allocated randomly into four groups of 20: Group 1-the restorations were light-cured for 40 s with a conventional light-curing unit (New Light VL-II); Group 2-the restorations were cured with Candelux using a two-step mode; Group 3-the restorations were cured with Astralis 7 using a ramping mode; Group 4-the restorations were light-cured for 3 s with a plasma arc light-curing unit (Wave Light). Half of the specimens from each group were subjected to thermocycling (5-60 degrees C, 15 s dwell time, 5000 cycles) prior to immersion in 0.5% basic fuchsin. The teeth were sectioned and the degrees of dye penetration were scored. The data were analyzed with either the Kruskal-Wallis test or the Mann-Whitney U-test (p < 0.05) RESULTS: No significant differences were found in the microleakage scores among the light-curing modes used. The restorations tended to display more microleakage when they were subjected to thermocycling, but the differences were not statistically significant. CONCLUSIONS: These findings suggest that light-curing modes may have no effect on the microleakage of cervical cavities with a small C-factor, as is the case in this study.

Sandblasting of inlay margin--marginal abrasion and bond strength.

Specimens (such as metal inlays) with 30 degrees or 45 degrees marginal bevel were prepared by casting with a 12% Au-Pd-Ag alloy or a gold alloy. A form of the marginal bevel was traced on a profile projector before and after sandblasting, and the length of the abraded margin measured. All the blasting conditions abraded the marginal bevel, while the blasting at 20 mm for 2 seconds brought about the least abrasion of approximately 10 microm in the 45 degrees specimen cast with Au-Pd-Ag alloy. The gold alloy specimens were abraded more than the Au-Pd-Ag alloy ones; those with marginal bevel of 30 degrees were abraded more than those of 45 degrees. On the other hand, the effect of different blasting conditions on the bond strength of units bonded with resin cement was evaluated (under selected blasting conditions known to cause relatively less damage to the marginal level). Specimens treated by sandblaster exhibited a comparable tensile bond strength, while specimens without sandblasting but applied with only an alloy primer showed a statistically low value.

Effect of low-viscosity resin-based composite on the microleakage of cervical restorations.

PURPOSE: To investigate the effect of a low-viscosity resin-based composite (LVC) liner on the microleakage of cervical resin-based composites bonded with new adhesive systems. METHODS: 180 wedge-shaped cervical cavities on bovine incisors were treated with AQ Bond (all-in-one), ABF (experimental two-step self-etching primer containing antibacterial monomer) or Clearfil SE Bond (two-step self-etching primer) systems according to the manufacturers' instructions. Half of the treated cavities in each adhesive system were lined with an LVC (Protect Liner F) and filled with a hybrid resin-based composite (Clearfil AP-X). Ten specimens from each group were immersed in 0.5% basic fuchsin solution immediately after finishing the restorations. The specimens to be subjected to thermocycling (5-60 degrees C, 15 seconds dwell time, 5,000 cycles) or to flexural load cycling (approximately 0.5 mm labio-lingual displacement at the incisal edge, 10,000 cycles, 1 Hz) prior to immersion in the dye solution were also prepared. The teeth were sectioned through the center of the restorations and the degrees of dye penetration were scored. The data were analyzed with the Mann-Whitney U-test or the Kruskal-Wallis test (P < 0.05). RESULTS: The use of the LVC liner significantly improved marginal sealing of AQ Bond. However, the LVC liner could not prevent the deterioration in the marginal integrity caused by thermocycling or flexural load cycling. In the case of ABF, the use of the LVC liner showed a trend toward less microleakage. For Clearfil SE Bond, the LVC liner prevented the deterioration in the marginal seal caused by thermocycling.