Abnormal intestinal motor patterns explain enteric colonization with gram-negative bacilli in late radiation enteropathy

Multi-Disciplinary Management in Rectal Cancer Survivorship: A Clinical Practice Review

Colorectal cancer (CRC) is the third most common cancer in the USA and worldwide. In the USA, nearly one-third of CRC cases are anatomically classified as rectal cancer. Over the past few decades, continued refinement of multimodality treatment and the introduction of new therapeutic agents have enhanced curative treatment rates and quality of life outcomes. As treatments improve and the incidence of young onset rectal cancer rises, the number of rectal cancer survivors grows each year. This trend highlights the growing importance of rectal cancer survivorship. Multimodality therapy with systemic chemotherapy, chemoradiation, and surgery can result in chronic toxicities in multiple organ systems, requiring a multi-disciplinary care model with services ranging from appropriate cancer surveillance to management of long-term toxicities and optimization of modifiable risk factors. Here, we review the evidence on these long-term toxicities and provide management considerations from consensus guidelines. Specific topics include bowel dysfunction from radiation and surgery, oxaliplatin-induced neuropathy, accelerated bone degeneration, the impact of fluoropyrimidines on long-term cardiovascular health, urinary incontinence, sexual dysfunction, and psychosocial distress. Additionally, we review modifiable risk factors to inform providers and rectal cancer survivors of various lifestyle and behavioral changes that can be made to improve their long-term health outcomes.

Exploiting dietary fibre and the gut microbiota in pelvic radiotherapy patients

With an ageing population, there is an urgent need to find alternatives to current standard-of-care chemoradiation schedules in the treatment of pelvic malignancies. The gut microbiota may be exploitable, having shown a valuable role in improving patient outcomes in anticancer immunotherapy. These bacteria feed on dietary fibres, which reach the large intestine intact, resulting in the production of beneficial metabolites, including short-chain fatty acids. The gut microbiota can impact radiotherapy (RT) treatment responses and itself be altered by the radiation. Evidence is emerging that manipulation of the gut microbiota by dietary fibre supplementation can improve tumour responses and reduce normal tissue side effects following RT, although data on tumour response are limited to date. Both may be mediated by immune and non-immune effects of gut microbiota and their metabolites. Alternative approaches include use of probiotics and faecal microbiota transplantation (FMT). Current evidence will be reviewed regarding the use of dietary fibre interventions and gut microbiota modification in improving outcomes for pelvic RT patients. However, data regarding baseline (pre-RT) gut microbiota of RT patients and timing of dietary fibre manipulation (before or during RT) is limited, heterogenous and inconclusive, thus more robust clinical studies are required before these strategies can be applied clinically.

Prolonged lipopolysaccharide-induced illness elevates glucagon-like peptide-1 and suppresses peptide YY: A human-randomized cross-over trial

Severe systemic inflammation is associated with nausea, loss of appetite, and delayed gastric emptying, which increases hospitalization admission length and mortality rate. There is a lack of human controlled studies exploring gastric emptying rates and underlying mechanisms during inflammatory conditions. We aimed to investigate if systemic inflammation in young men delays gastro-intestinal transit times, lowers motility, and affects gastrointestinal hormone secretion. This substudy of a randomized crossover trial investigated eight healthy young men on two separate occasions; (I) following an overnight fast (healthy conditions/HC) and (II) fasting and bedrest combined with two lipopolysaccharide (LPS) injections of 1 ng kg-1 following an overnight fast and 0.5 ng kg-1 following another 24 h (systemic inflammation/SI). A standardized protein beverage and a SmartPill capsule (a wireless gastrointestinal monitoring system) were swallowed during each occasion. Whole gut transit time was comparable between HC and SI. SI decreased gastric mean pressure peak amplitude (p = 0.04) and increased pH rise across the pylorus and small bowel pH (p = 0.02) compared with HC. Glucagon-like peptide-1 was elevated during SI compared with HC (p = 0.04). Peptide YY was lower during SI compared with HC (p = 0.007). Prolonged LPS exposure combined with fasting and bedrest elevated glucagon-like peptide 1 concentrations, which may play a role for the nausea and loss of appetite typically associated with SI.

Gut Microbiome and Its Associations With Acute and Chronic Gastrointestinal Toxicities in Cancer Patients With Pelvic Radiation Therapy: A Systematic Review

Aim

Pelvic radiation therapy (RT) can impact the gut microbiome in patients with cancer and result in gastrointestinal (GI) toxicities. The purpose of this systematic review was to describe the effects of RT on the gut microbiome and the associations between the gut microbiome and GI toxicities in patients treated with pelvic RT.

Methods

PubMed, Embase, and Web of Science databases were searched from their earliest records to August 2020. The articles screening process adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The Mixed Method Assessment Tool was used to assess the methodological quality for each included study. All study findings were synthesized and presented in narrative format. Thirteen studies were included. The gut microbiome of fecal samples was analyzed using 16S rRNA sequencing approaches.

Results

There were disparities in alpha and beta diversities that existed across the studies. Divergent results were found among various phyla, including Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria, Cyanobacteria, Fusobacteria, and Deinococcus-Thermus. Moreover, alteration in the gut microbiome diversity and abundance related to cancer treatment was associated with pelvic toxicities, specifically diarrhea. Following treatment, increases in the abundance of Bacteroides was associated with diarrhea and radiation enteritis.

Conclusions

Pelvic RT can disrupt the diversity and abundance of commensal gut microorganisms. A dysbiotic gut microbiome showed a promising association with radiation enteritis through alterations of the intestinal barrier function, innate immunity, and intestinal repair mechanisms; however, confounders, such as diet, were not thoroughly addressed.

The impact of non-antimicrobial drug agents on the acquisition of ESBL-producing Enterobacterales in non-critical care wards in a German university hospital: an exploratory, matched case-control study

OBJECTIVES

To investigate therapeutical drugs other than antimicrobials as risk factors for the acquisition of ESBL-producing Enterobacterales (ESBL-E).

METHODS

This matched case-control study is based on rectal surveillance screening data obtained during a larger trial between 2014 and 2016 upon patients' admission and at least once before discharge in eight non-ICU wards. Patients with ward-acquired ESBL-E (cases) were matched 1:1 to non-ESBL-E carriers (controls) based on ward, number of screening samples, days at risk and Charlson comorbidity index (CCI). Daily medication data were documented according to the Anatomical Therapeutic Chemical classification system. Multivariable conditional logistic regression models were used to calculate risk factors for ESBL-E acquisition.

RESULTS

Of the 232 cases and 232 controls analysed, baseline characteristics such as gender (male 56.9%), median age (65 years old, IQR 52-74), number of screening samples (N = 3, IQR 2-4), days to first sample (2, IQR 1-2), days at risk (8, IQR 6-11) and CCI (4, IQR 2-6) were similar. Multivariable analysis showed that glucocorticoids, opium alkaloids and selective β-2-adrenoreceptor agonists increased the chance to detect ESBL-E (OR 1.07, 95% CI 1.001-1.13, P = 0.047; OR 1.06, 95% CI 1.007-1.12, P = 0.027; and OR 1.31, 95% CI 1.105-1.55, P = 0.001, respectively), while antihistamines decreased it (OR 0.61, 95% CI 0.39-0.97, P = 0.034). In a sensitivity analysis, including drugs prescribed to at least 50 patients, proton pump inhibitors remained as risk factors (OR 1.049, 95% CI 1.001-1.100, P = 0.047).

CONCLUSIONS

In a non-ICU setting, drugs other than antimicrobials were determined as potential independent risk factors for ESBL-E acquisition.

The impact of pelvic radiotherapy on the gut microbiome and its role in radiation-induced diarrhoea: a systematic review

Pelvic radiotherapy is the key treatment for pelvic malignancies, usually including pelvic primary tumour lesions and lymphatic drainage areas in the pelvic region. Therefore, the intestinal tract in the radiation field is inevitably damaged, a phenomenon clinically referred to as radiation enteritis, and diarrhoea is the most common clinical symptom of radiation enteritis. Therefore, it is necessary to study the mechanism of radiation-induced diarrhoea. It has been found that the gut microbiome plays an important role in the development of diarrhoea in response to pelvic radiotherapy, and the species and distribution of intestinal microbiota are significantly altered in patients after pelvic radiotherapy. In this study, we searched for articles indexed in the Cochrane Library, Web of Science, EMBASE and PubMed databases in English and CNKI, Wanfang data and SINOMED in Chinese from their inception dates through 13 March 2020 to collect studies on the gut microbiome in pelvic radiotherapy patients. Eventually, we included eight studies: one study report on prostatic carcinoma, five studies on gynaecological carcinoma and two papers on pelvic carcinomas. All studies were designed as self-controlled studies, except for one that compared toxicity to nontoxicity. The results from all the studies showed that the diversity of intestinal flora decreased during and after pelvic radiotherapy, and the diversity of intestinal flora decreased significantly in patients with diarrhoea after radiotherapy. Five studies observed that the community composition of the gut microbiota changed at the phylum, order or genus level before, during, and after pelvic radiotherapy at different time points. In addition, the composition of the gut microbiota before radiotherapy was different between patients with postradiotherapy diarrhoea and those without diarrhoea in five studies. However, relevant studies have not reached consistent results regarding the changes in microbiota composition. Changes in the intestinal flora induced by pelvic radiotherapy and their relationship between changes in intestinal flora and the occurrence of radiation-induced diarrhoea (RID) are discussed in this study, providing a theoretical basis for the causes of RID after pelvic radiotherapy.

The Impact of Gut Microbiota on Radiation-Induced Enteritis

Radiotherapy is an important treatment for abdominal tumors. A critical side effect for this therapy is enteritis. In this review, we aim to summarize recent findings in radiation enteritis, in particular the role of gut microbiota dysbiosis in the development and therapy of the disease. Gut microbiota dysbiosis plays an important role in the occurrence of various diseases, such as radiation enteritis. Abdominal radiation results in changes in the composition of microbiota and reduces its diversity, which is mainly reflected in the decrease of Lactobacillus spp. and Bifidobacterium spp. and increase of Escherichia coli and Staphylococcus spp. Gut microbiota dysbiosis aggravates radiation enteritis, weakens intestinal epithelial barrier function, and promotes inflammatory factor expression. Pathogenic Escherichia coli induce the rearrangement and redistribution of claudin-1, occludin, and ZO-1 in tight junctions, a critical component in intestinal epithelial barrier. In view of the role that microbiome plays in radiation enteritis, we believe that intestinal flora could be a potential biomarker for the disease. Correction of microbiome by application of probiotics, fecal microbiota transplantation (FMT), and antibiotics could be an effective method for the prevention and treatment of radiation-induced enteritis.

Review: Effect of Gut Microbiota and Its Metabolite SCFAs on Radiation-Induced Intestinal Injury

Gut microbiota is regarded as the second human genome and forgotten organ, which is symbiotic with the human host and cannot live and exist alone. The gut microbiota performs multiple physiological functions and plays a pivotal role in host health and intestinal homeostasis. However, the gut microbiota can always be affected by various factors and among them, it is radiotherapy that results in gut microbiota ¹²dysbiosis and it is often embodied in a decrease in the abundance and diversity of gut microbiota, an increase in harmful bacteria and a decrease in beneficial bacteria, thereby affecting many disease states, especially intestine diseases. Furthermore, gut microbiota can produce a variety of metabolites, among which short-chain fatty acids (SCFAs) are one of the most abundant and important metabolites. More importantly, SCFAs can be identified as second messengers to promote signal transduction and affect the occurrence and development of diseases. Radiotherapy can lead to the alterations of SCFAs-producing bacteria and cause changes in SCFAs, which is associated with a variety of diseases such as radiation-induced intestinal injury. However, the specific mechanism of its occurrence is not yet clear. Therefore, this review intends to emphasize the alterations of gut microbiota after radiotherapy and highlight the alterations of SCFAs-producing bacteria and SCFAs to explore the mechanisms of radiation-induced intestinal injury from the perspective of gut microbiota and its metabolite SCFAs.

Intestinal dysmotility after bowel resection in rats is associated with decreased ghrelin and vimentin expression and loss of intestinal cells of Cajal

This study provides novel insight into the mechanisms of intestinal dysmotility following massive small bowel resection. We show that 2 wk after bowel resection in rats, impaired intestinal motility was associated with loss of interstitial cells of Cajal (ICC; downregulation of transmembrane member 16A (TMEM16A) and c-kit expression) as well as with decreased vimentin, desmin, and ghrelin levels. Impaired intestinal motility led to a decrease in final body weight, suggesting less effective nutrient absorption. The purpose of this study was to evaluate the mechanisms of intestinal motility in a rat model of short bowel syndrome (SBS). Rats were divided into three groups: Sham rats underwent bowel transection; SBS-NSI rats underwent a 75% bowel resection and presented with normal intestinal size (NSI) at euthanasia and hypermotility patterns; SBS-DYS showed dysmotile (DYS) enlarged intestine and inhibited motility patterns. Animals were euthanized after 2 wk. Illumina's digital gene expression (DGE) analysis was used to determine the intestinal motility-related gene expression profiling in mucosal samples. Intestinal motility-related and ICC genes and protein expression in intestinal muscle layer were determined using real-time PCR, Western blotting, and immunohistochemistry. Gastrointestinal tract motility was studied by microcomputer tomography. From 10 Ca²⁺ signaling pathway-related genes, six genes in jejunum and seven genes in ileum were downregulated in SBS vs. Sham animals. Downregulation of TMEM16A mRNA and protein was confirmed by real-time PCR. Rapid intestinal transit time in SBS-NSI rats correlated with a mild decrease in TMEM16A, c-kit, and vimentin mRNA and protein expression (vs/. Sham animals). SBS-DYS rats demonstrated enlarged intestinal loops and delayed small intestinal emptying (on imaging studies) that were correlated with marked downregulation in TMEM16A, c-kit, vimentin, and ghrelin mRNA and protein levels compared with the other two groups. In conclusion, 2 wk following massive bowel resection in rats, impaired intestinal motility was associated with decreased vimentin and ghrelin gene and protein levels as well as loss of ICC (c-kit and TMEM16A).NEW & NOTEWORTHY This study provides novel insight into the mechanisms of intestinal dysmotility following massive small bowel resection. We show that 2 weeks after bowel resection in rats, impaired intestinal motility was associated with loss of interstitial cells of Cajal (downregulation of TMEM 16A, and c-kit expression) as well as with decreased vimentin, desmin, and ghrelin levels. Impaired intestinal motility led to decrease in final body weight, suggesting less effective nutrient absorption.

The Gut Microbiome Is Associated With Therapeutic Responses and Toxicities of Neoadjuvant Chemoradiotherapy in Rectal Cancer Patients-A Pilot Study

Responses to neoadjuvant chemoradiotherapy (nCRT) and therapy-related toxicities in rectal cancer vary among patients. To provide the individualized therapeutic option for each patient, predictive markers of therapeutic responses and toxicities are in critical need. We aimed to identify the association of gut microbiome with and its potential predictive value for therapeutic responses and toxicities. In the present study, we collected fecal microbiome samples from patients with rectal cancer at treatment initiation and just after nCRT. Taxonomic profiling via 16S ribosomal RNA gene sequencing was performed on all samples. Patients were classified as responders versus non-responders. Patients were grouped into no or mild diarrhea and severe diarrhea. STAMP and high-dimensional class comparisons via linear discriminant analysis of effect size (LEfSe) were used to compare the compositional differences between groups. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) was utilized to predict differences in metabolic function between groups. Ten patients were classified as responders and 12 patients were classified as non-responders. Fourteen patients experienced no or mild diarrhea and 8 patients experienced severe diarrhea. Several bacteria taxa with significantly different relative abundances before and after nCRT were identified. Similarly, several baseline bacteria taxa and predicted pathways with significantly different relative abundances between responders and non-responders or between patients no or mild diarrhea and severe diarrhea were identified. Specifically, Shuttleworthia was identified as enriched in responders and several bacteria taxa in the Clostridiales order etc. were identified as enriched in non-responders. Pathways including fatty acid metabolism were predicted to be enriched in responders. In addition, Bifidobacterium, Clostridia, and Bacteroides etc. were identified as enriched in patients with no or mild diarrhea. Pathways including primary bile acid biosynthesis were predicted to be enriched in patients with no or mild diarrhea. Together, the microbiota and pathway markers identified in this study may be utilized to predict the therapeutic responses and therapy-related toxicities of nCRT in patients with rectal cancer. More patient data is needed to verify the current findings and the results of metagenomic, metatranscriptomic, and metabolomic analyses will further mine key biomarkers at the compositional and functional level.

A Minireview on Gastrointestinal Microbiota and Radiosusceptibility

Gastrointestinal (GI) microbiota maintains a symbiotic relationship with the host and plays a key role in modulating many important biological processes and functions of the host, such as metabolism, inflammation, immune and stress response. It is becoming increasingly apparent that GI microbiota is susceptible to a wide range of environmental factors and insults, for examples, geographic location of birth, diet, use of antibiotics, and exposure to radiation. Alterations in GI microbiota link to various diseases, including radiation-induced disorders. In addition, GI microbiota composition could be used as a biomarker to estimate radiosusceptibility and radiation health risk in the host. In this minireview, we summarized the documented studies on radiation-induced alterations in GI microbiota and the relationship between GI microbiota and radiosusceptibility of the host, and mainly discussed the possible mechanisms underlying GI microbiota influencing the outcome of radiation response in humans and animal models. Furthermore, we proposed that GI microbiota manipulation may be used to reduce radiation injury and improve the health of the host.

Bidirectional and dynamic interaction between the microbiota and therapeutic resistance in pancreatic cancer

Pancreatic ductal adenocarcinoma is one of the most lethal malignancies and is known for its high resistance and low response to treatment. Cancer treatments can reshape the microbiota and in turn, the microbiota influences the therapeutic efficacy by regulating immune response and metabolism. This crosstalk is bidirectional, heterogeneous, and dynamic. In this review, we elaborated on the interactions between the microbiota and therapeutic resistance in pancreatic ductal adenocarcinoma. Regulating the microbiota in pancreatic tumor microenvironment may not only generate direct anti-cancer but also synergistic effects with other treatments, providing new directions in cancer therapy.

Small Intestinal Bacterial Overgrowth: How to Diagnose and Treat (and Then Treat Again)

Small intestinal bacterial overgrowth (SIBO) is a condition with presentation that can vary from asymptomatic to steatorrhea and malnutrition. Small bowel aspiration and culture is the current gold standard of diagnosis; however, this is invasive and is not without risk to the patient. Breath testing is a noninvasive and less expensive alternative method; however, it lacks diagnostic sensitivity and specificity. Novel diagnostic methods being studied include gas-sensing capsules. The mainstay of treatment is antibiotics; alternative therapies include herbal medications, dietary modifications, and prokinetic agents. Further investigation into less invasive and less harmful diagnostic methods and treatment options is warranted.

ACG Clinical Guideline: Small Intestinal Bacterial Overgrowth

Small intestinal bacterial overgrowth is defined as the presence of excessive numbers of bacteria in the small bowel, causing gastrointestinal symptoms. This guideline statement evaluates criteria for diagnosis, defines the optimal methods for diagnostic testing, and summarizes treatment options for small intestinal bacterial overgrowth. This guideline provides an evidence-based evaluation of the literature through the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) process. In instances where the available evidence was not appropriate for a formal GRADE recommendation, key concepts were developed using expert consensus.

Abnormal small bowel motility in patients with hereditary transthyretin amyloidosis

BACKGROUND

Gastrointestinal complications are common in hereditary transthyretin amyloid (ATTRm) amyloidosis. The underlying mechanisms have not been fully elucidated, and the patients' small bowel function remains largely unexplored. The aim of the present study was to compare the small bowel motility in ATTRm amyloidosis patients with that in non-amyloidosis patient controls.

METHODS

ATTRm amyloidosis patients undergoing evaluation for liver transplantation were consecutively investigated with 24-hour duodenojejunal manometry (n = 19). The somatostatin analogue octreotide was used to induce fasting motility. Patients with age at onset of ≥50 years were defined as late-onset cases. For each patient, three age- and sex-matched patient controls (n = 57) were selected from the total pool of investigated patients.

KEY RESULTS

Manometry was judged as abnormal in 58% of the patients and in 26% of the patient controls (P = .01). Patients displayed significantly more daytime phase III migrating motor complexes than patient controls (median 4 vs 2, P < .01), and had a higher frequency of low-amplitude complexes (16% vs 4%; however, this difference did not reach statistical significance, P = .10). Furthermore, late-onset patients showed a delay in octreotide response (5.4 vs 3.8 minutes, P < .01), but this was not observed for early-onset patients or within the control group.

CONCLUSIONS AND INFERENCES

Patients with ATTRm amyloidosis displayed abnormalities in their small bowel motility more frequently than non-amyloidosis patient controls, and the manometric pattern was probably best consistent with a combined neuromyopathic disorder. The delayed octreotide response in late-onset patients warrants further investigation.

Vagal dysfunction and small intestinal bacterial overgrowth: novel pathways to chronic inflammation in HIV

OBJECTIVE

Chronic inflammation in HIV-infected individuals drives disease progression and the development of comorbidities, despite viral suppression with combined antiretroviral therapy. Here, we sought evidence that vagal dysfunction, which occurs commonly as part of HIV-associated autonomic neuropathy, could exacerbate inflammation through gastrointestinal dysmotility, small intestinal bacterial overgrowth (SIBO), and alterations in patterns of soluble immune mediators.

DESIGN

This is a cross-sectional observational study.

METHODS

Forty participants on stable combined antiretroviral therapy with gastrointestinal symptoms, and no causes for vagal or gastrointestinal dysfunction other than HIV, underwent autonomic testing, hydrogen/methane breath testing for SIBO, and gastric emptying scintigraphy. A panel of 41 cytokines, high-mobility group box 1, and markers of bacterial translocation (lipopolysaccharide) and monocyte/macrophage activation (sCD14 and sCD163) were tested in plasma.

RESULTS

We found that participants with vagal dysfunction had delayed gastric emptying and higher prevalence of SIBO. SIBO was associated with IL-6, but not sCD14; lipopolysaccharide could not be detected in any participant. We also found alteration of cytokine networks in participants with vagal dysfunction, with stronger and more numerous positive correlations between cytokines. In the vagal dysfunction group, high mobility group box 1 was the only soluble mediator displaying strong negative correlations with other cytokines, especially those cytokines that had numerous other strong positive correlations.

CONCLUSION

The current study provides evidence that the vagal component of HIV-associated autonomic neuropathy is associated with changes in immune and gastrointestinal function in individuals with well treated HIV. Further study will be needed to understand whether therapies targeted at enhancing vagal function could be of benefit in HIV.

Nutritional strategies to prevent gastrointestinal toxicity during pelvic radiotherapy

Radiotherapy-induced damage to non-cancerous gastrointestinal mucosa has effects on secretory and absorptive functions and can interfere with normal gastrointestinal physiology. Nutrient absorption and digestion may be compromised. Dietary manipulation is an attractive option with sound rationale for intervention. The aim of this review was to synthesise published evidence for the use of elemental formulae, low or modified fat diets, fibre, lactose restriction and probiotics, prebiotics and synbiotics to protect the bowel from gastrointestinal side effects during long-course, radical pelvic radiotherapy. Thirty original studies (recruiting n 3197 patients) were identified comprising twenty-four randomised controlled trials, four cohort studies and two comparator trials. Endpoints varied and included symptom scales (Inflammatory Bowel Disease Questionnaire, Common Technology Criteria for Adverse Events, Radiation Therapy Oncology Group) and Bristol Stool Scale. Dietary and supplement interventions were employed with many studies using a combination of interventions. Evidence from RCT was weak for elemental, low or modified fat and low-lactose interventions and modestly positive for the manipulation of fibre during radiotherapy. Evidence for probiotics as prophylactic interventional agents was more promising with a number of trials reporting positive results but strength and strains of interventions vary, as do methodologies and endpoints making it difficult to arrive at firm conclusions with several studies lacking statistical power. This consolidated review concludes that there is insufficient high-grade evidence to recommend nutritional intervention during pelvic radiotherapy. Total replacement of diet with elemental formula could be effective in severe toxicity but this is unproven. Probiotics offer promise but cannot be introduced into clinical practice without rigorous safety analysis, not least in immunocompromised patients.

Obesity increases the risk of small intestinal bacterial overgrowth (SIBO)

BACKGROUND

Small intestinal bacterial overgrowth (SIBO) has been associated with anatomical and motility-related abnormalities. Specifically, obesity has been postulated to alter small bowel motility, leading to SIBO.

AIMS

(i) Assess the prevalence of SIBO in obesity; (ii) determine the relationship of obesity and SIBO, using small bowel transit time (SBTT) and pH; (iii) profile the gut microbiome in obese and non-obese patients with SIBO.

METHODS

Thirty consecutive participants referred for SIBO underwent lactulose breath tests (LBTs) and wireless motility capsule (WMC) studies. Composition of the intestinal microbiome was assessed by analyzing samples from three different gastrointestinal sites via 16S rRNA gene-sequencing.

KEY RESULTS

SIBO was more frequent among obese patients vs non-obese patients (88.9% vs 42.9%, P < .05). Obesity did not correlate with small bowel transit time (SBTT), gastric pH, and small bowel pH. In patients with normal SBTT, obesity was associated with an 11-fold increase (P = .05) in the risk of SIBO. Whereas in those with prolonged SBTT, there was no correlation between obesity and SIBO. Obese vs non-obese patients exhibited significant differences in microbiome diversity in rectal samples. Obesity was associated with increased odds of developing SIBO (P = .04) in multivariate regression analyses.

CONCLUSIONS AND INFERENCES

While obesity was significantly associated with SIBO, our findings suggest that alterations in gut pH, SBTT, and decline in species richness do not account for the obesity-SIBO relationship.

Bowel Radiation Injury: Complexity of the Pathophysiology and Promises of Cell and Tissue Engineering

Ionizing radiation is effective to treat malignant pelvic cancers, but the toxicity to surrounding healthy tissue remains a substantial limitation. Early and late side effects not only limit the escalation of the radiation dose to the tumor but may also be life-threatening in some patients. Numerous preclinical studies determined specific mechanisms induced after irradiation in different compartments of the intestine. This review outlines the complexity of the pathogenesis, highlighting the roles of the epithelial barrier in the vascular network, and the inflammatory microenvironment, which together lead to chronic fibrosis. Despite the large number of pharmacological molecules available, the studies presented in this review provide encouraging proof of concept regarding the use of mesenchymal stromal cell (MSC) therapy to treat radiation-induced intestinal damage. The therapeutic efficacy of MSCs has been demonstrated in animal models and in patients, but an enormous number of cells and multiple injections are needed due to their poor engraftment capacity. Moreover, it has been observed that although MSCs have pleiotropic effects, some intestinal compartments are less restored after a high dose of irradiation. Future research should seek to optimize the efficacy of the injected cells, particularly with regard to extending their life span in the irradiated tissue. Moreover, improving the host microenvironment, combining MSCs with other specific regenerative cells, or introducing new tissue engineering strategies could be tested as methods to treat the severe side effects of pelvic radiotherapy.

Radiation induces proinflammatory dysbiosis: transmission of inflammatory susceptibility by host cytokine induction

OBJECTIVE

Radiation proctitis (RP) is a complication of pelvic radiotherapy which affects both the host and microbiota. Herein we assessed the radiation effect on microbiota and its relationship to tissue damage using a rectal radiation mouse model.

DESIGN

We evaluated luminal and mucosa-associated dysbiosis in irradiated and control mice at two postradiation time points and correlated it with clinical and immunological parameters. Epithelial cytokine response was evaluated using bacterial-epithelial co-cultures. Subsequently, germ-free (GF) mice were colonised with postradiation microbiota and controls and exposed to radiation, or dextran sulfate-sodium (DSS). Interleukin (IL)-1β correlated with tissue damage and was induced by dysbiosis. Therefore, we tested its direct role in radiation-induced damage by IL-1 receptor antagonist administration to irradiated mice.

RESULTS

A postradiation shift in microbiota was observed. A unique microbial signature correlated with histopathology. Increased colonic tumor necrosis factor (TNF)α, IL-1β and IL-6 expression was observed at two different time points. Adherent microbiota from RP differed from those in uninvolved segments and was associated with tissue damage. Using bacterial-epithelial co-cultures, postradiation microbiota enhanced IL-1β and TNFα expression compared with naïve microbiota. GF mice colonisation by irradiated microbiota versus controls predisposed mice to both radiation injury and DSS-induced colitis. IL-1 receptor antagonist administration ameliorated intestinal radiation injury.

CONCLUSIONS

The results demonstrate that rectal radiation induces dysbiosis, which transmits radiation and inflammatory susceptibility and provide evidence that microbial-induced radiation tissue damage is at least in part mediated by IL-1β. Environmental factors may affect the host via modifications of the microbiome and potentially allow for novel interventional approaches via its manipulation.

Impact of Long-Term Proton Pump Inhibitor Therapy on Gut Microbiota in F344 Rats: Pilot Study

Background/Aims

To evaluate changes in gut microbiota composition following long-term proton pump inhibitor (PPI) treatment.

Methods

Twenty-four-week-old F344 rats were fed diets with (n=6) or without (n=5) lansoprazole for 50 weeks. Profiles of luminal microbiota in the terminal ileum were then analyzed. Pyrosequencing of the 16S rRNA gene was performed using an FLX genome sequencer (454 Life Sciences/Roche).

Results

Rats treated with lansoprazole showed significantly reduced body weights compared to controls (lansoprazole-treated rats and controls, 322.3±15.3 g vs 403.2±5.2 g, respectively, p<0.001). However, stool frequencies and consistencies did not differ between the two groups. The composition of the gut microbiota in lansoprazole-treated rats was quite different from that of the controls. In the controls, the microbiota profiles obtained from the terminal ileum showed a predominance of Proteobacteria (93.9%) due to the abundance of Escherichia and Pasteurella genera. Conversely, lansoprazole-treated rats showed an elevated population of Firmicutes (66.9%), which was attributed to an increased ratio of Clostridium g4 to Lactobacillus genera.

Conclusions

This preliminary study suggests that long-term administration of PPI may cause weight loss and changes to the microbiota in the terminal ileum.

Probiotics for prevention of radiation-induced diarrhea: A meta-analysis of randomized controlled trials

Background

Radiotherapy is commonly used for abdominal or pelvic cancer, and patients receiving radiotherapy have a high risk developing to an acute radiation-induced diarrhea. Several previous studies have discussed the effect of probiotics on prevention of radiation-induced diarrhea, but the results are still inconsistent.

Objective

We performed a meta-analysis of randomized controlled trials (RCTs) to evaluate the efficacy of probiotic supplementation for prevention the radiation-induced diarrhea.

Methods

Relevant RCTs studies assessing the effect of probiotic supplementation on clinical outcomes compared with placebo were searched in PubMed, EMBASE, and the Cochrane Library databases (up to March 30 2016). Heterogeneity was assessed with I² and H², and publication bias was evaluated using sensitive analysis.

Results

Six trials, a total of 917 participants (490 participants received prophylactic probiotics and 427 participants received placebo), were included in this meta-analysis. Compared with placebo, probiotics were associated with a lower incidence of radiation-induced diarrhea (RR: 0.55; 95% CI: 0.34–0.88; P = 0.01; I²: 87%; 95% CI: 75%-94%; H²: 2.8; 95% CI: 2.0–4.0). However, there is no significant difference in the anti-diarrheal medication use (RR: 0.68; 95% CI: 0.40–1.14; P = 0.14) or bristol scale on stool form (RR: 0.64; 95% CI: 0.35–1.17; P = 0.14).

Conclusion

Probiotics may be beneficial to prevent radiation-induced diarrhea in patients who suffered from abdominal or pelvic cancers during radiotherapy period.

An Integrated Multi-Omic Approach to Assess Radiation Injury on the Host-Microbiome Axis

Medical responders to radiological and nuclear disasters currently lack sufficient high-throughput and minimally invasive biodosimetry tools to assess exposure and injury in the affected populations. For this reason, we have focused on developing robust radiation exposure biomarkers in easily accessible biofluids such as urine, serum and feces. While we have previously reported on urine and serum biomarkers, here we assessed perturbations in the fecal metabolome resulting from exposure to external X radiation in vivo. The gastrointestinal (GI) system is of particular importance in radiation biodosimetry due to its constant cell renewal and sensitivity to radiation-induced injury. While the clinical GI symptoms such as pain, bloating, nausea, vomiting and diarrhea are manifested after radiation exposure, no reliable bioindicator has been identified for radiation-induced gastrointestinal injuries. To this end, we focused on determining a fecal metabolomic signature in X-ray irradiated mice. There is overwhelming evidence that the gut microbiota play an essential role in gut homeostasis and overall health. Because the fecal metabolome is tightly correlated with the composition and diversity of the microorganism in the gut, we also performed fecal 16S rRNA sequencing analysis to determine the changes in the microbial composition postirradiation. We used in-house bioinformatics tools to integrate the 16S rRNA sequencing and metabolomic data, and to elucidate the gut integrated ecosystem and its deviations from a stable host-microbiome state that result from irradiation. The 16S rRNA sequencing results indicated that radiation caused remarkable alterations of the microbiome in feces at the family level. Increased abundance of common members of Lactobacillaceae and Staphylococcaceae families, and decreased abundances of Lachnospiraceae, Ruminococcaceae and Clostridiaceae families were found after 5 and 12 Gy irradiation. The metabolomic data revealed statistically significant changes in the microbial-derived products such as pipecolic acid, glutaconic acid, urobilinogen and homogentisic acid. In addition, significant changes were detected in bile acids such as taurocholic acid and 12-ketodeoxycholic acid. These changes may be associated with the observed shifts in the abundance of intestinal microbes, such as R. gnavus , which can transform bile acids.

Reducing radiation-induced gastrointestinal toxicity - the role of the PHD/HIF axis

Radiotherapy is an effective treatment strategy for cancer, but a significant proportion of patients experience radiation-induced toxicity due to damage to normal tissue in the irradiation field. The use of chemical or biological approaches aimed at reducing or preventing normal tissue toxicity induced by radiotherapy is a long-held goal. Hypoxia-inducible factors (HIFs) regulate the production of factors that may protect several cellular compartments affected by radiation-induced toxicity. Pharmacological inhibitors of prolyl hydroxylase domain-containing enzymes (PHDs), which result in stabilization of HIFs, have recently been proposed as a new class of radioprotectors. In this review, radiation-induced toxicity in the gastrointestinal (GI) tract and the main cellular compartments studied in this context will be discussed. The effects of PHD inhibition on GI radioprotection will be described in detail.

How to Test and Treat Small Intestinal Bacterial Overgrowth: an Evidence-Based Approach

Small intestinal bacterial overgrowth (SIBO) is characterized by an excessive amount of bacteria in the small intestine and a constellation of symptoms that include bloating, pain, gas, and diarrhea. Although known for many decades, there is a lack of consensus and clarity regarding the natural history and methods for its diagnosis. Several tests have been proposed, including the glucose breath test, lactulose breath test, small intestinal aspiration and culture, and others. However, there is a lack of standardization of these tests and their interpretation. Treatment of SIBO remains empirical; generally, broad spectrum antibiotics are recommended for 2 weeks (amoxicillin, rifaximin, ciprofloxacin, etc.) but evidence for their use is fair. Clearly, there is a strong need to develop a systematic approach for the management of SIBO and to perform multicenter clinical trials for the treatment of SIBO. In this review, we will discuss the current evidence for the diagnosis and treatment of SIBO, which includes (1) elimination/modification of the underlying causes, (2) induction of remission (antibiotics and elemental diet), and (3) maintenance of remission (promotility drugs, dietary modifications, repeat or cyclical antibiotics).

Small Bowel Bacterial Overgrowth in Children

OBJECTIVES

The aim of study was to perform a comprehensive review of the pathogenesis, available diagnostic procedures, prevalence, clinical manifestations, and consequences of small bowel bacterial overgrowth (SBBO) as well as treatment options in the pediatric population.

METHODS

A literature search including MEDLINE, PubMed, and Web of Science databases was performed.

RESULTS

SBBO is found in a variety of childhood conditions in which the normal homeostatic mechanisms restricting bacterial colonization in the small bowel are disturbed by congenital or acquired anatomical abnormalities, diminished gastric acid secretion, congenital alteration of intestinal motility or acquired small bowel diseases, or other chronic disorders including primary or acquired immunodeficiency. Data show that SBBO may be an underrecognized cause of pediatric morbidity. Although several diagnostic tests for SBBO determination are available, each has its drawbacks and limitations. Indeed, there is still no "criterion standard" for SBBO diagnosis in the pediatric population. Owing to lack of established guidelines and few published interventional studies that assess the effectiveness of SBBO therapy, treatment of children with SBBO remains empiric and comprises antibiotic or probiotic therapy.

CONCLUSIONS

Further research is needed to determine the clinical impact of SBBO and to establish diagnostic and therapeutic guidelines applicable to children.

Small Intestine Bacterial Overgrowth and Environmental Enteropathy in Bangladeshi Children

Recent studies suggest small intestine bacterial overgrowth (SIBO) is common among developing world children. SIBO’s pathogenesis and effect in the developing world are unclear. Our objective was to determine the prevalence of SIBO in Bangladeshi children and its association with malnutrition. Secondary objectives included determination of SIBO’s association with sanitation, diarrheal disease, and environmental enteropathy. We performed a cross-sectional analysis of 90 Bangladeshi 2-year-olds monitored since birth from an impoverished neighborhood. SIBO was diagnosed via glucose hydrogen breath testing, with a cutoff of a 12-ppm increase over baseline used for SIBO positivity. Multivariable logistic regression was performed to investigate SIBO predictors. Differences in concomitant inflammation and permeability between SIBO-positive and -negative children were compared with multiple comparison adjustment. A total of 16.7% (15/90) of the children had SIBO. The strongest predictors of SIBO were decreased length-for-age Z score since birth (odds ratio [OR], 0.13; 95% confidence interval [CI], 0.03 to 0.60) and an open sewer outside the home (OR, 4.78; 95% CI, 1.06 to 21.62). Recent or frequent diarrheal disease did not predict SIBO. The markers of intestinal inflammation fecal Reg 1β (116.8 versus 65.6 µg/ml; P = 0.02) and fecal calprotectin (1,834.6 versus 766.7 µg/g; P = 0.004) were elevated in SIBO-positive children. Measures of intestinal permeability and systemic inflammation did not differ between the groups. These findings suggest linear growth faltering and poor sanitation are associated with SIBO independently of recent or frequent diarrheal disease. SIBO is associated with intestinal inflammation but not increased permeability or systemic inflammation.

A total of 165 million children worldwide are considered stunted, which is associated with increased risk of death prior to age 5 years and cognitive disability. Stunting has, in part, been attributed to the presence of environmental enteropathy. Environmental enteropathy is a poorly understood condition leading to chronic intestinal inflammation. It has been postulated that small intestine bacterial overgrowth contributes to the pathogenesis of environmental enteropathy as overgrowth has been associated with intestinal inflammation and micronutrient malabsorption when it develops in other clinical contexts. This study confirms the finding that overgrowth occurs at high rates in the developing world. This is the first study to show that overgrowth is associated with intestinal inflammation and linear growth delay in this setting and is the first to examine why children with no known gastrointestinal dysfunction develop overgrowth from the developing world environment.

Prevalence of Small Intestinal Bacterial Overgrowth among Chronic Pancreatitis Patients: A Case-Control Study

Background. Patients with chronic pancreatitis (CP) exhibit numerous risk factors for the development of small intestinal bacterial overgrowth (SIBO). Objective. To determine the prevalence of SIBO in patients with CP. Methods. Prospective, single-centre case-control study conducted between January and September 2013. Inclusion criteria were age 18 to 75 years and clinical and radiological diagnosis of CP. Exclusion criteria included history of gastric, pancreatic, or intestinal surgery or significant clinical gastroparesis. SIBO was detected using a standard lactulose breath test (LBT). A healthy control group also underwent LBT. Results. Thirty-one patients and 40 controls were included. The patient group was significantly older (53.8 versus 38.7 years; P < 0.01). The proportion of positive LBTs was significantly higher in CP patients (38.7 versus 2.5%: P < 0.01). A trend toward a higher proportion of positive LBTs in women compared with men was observed (66.6 versus 27.3%; P = 0.056). The subgroups with positive and negative LBTs were comparable in demographic and clinical characteristics, use of opiates, pancreatic enzymes replacement therapy (PERT), and severity of symptoms. Conclusion. The prevalence of SIBO detected using LBT was high among patients with CP. There was no association between clinical features and the risk for SIBO.

Small Intestinal Transit Time Is Delayed in Small Intestinal Bacterial Overgrowth

BACKGROUND

Altered small intestinal motility is thought to contribute to the development of small intestinal bacterial overgrowth (SIBO). The clinical manifestations of SIBO and consequent malabsorption are wide ranging and include abdominal pain, bloating, diarrhea, weight loss, and nutritional deficiencies. However, due to the nonspecific nature of symptoms, the diagnosis may often be overlooked. To date, few studies have illustrated a direct relationship between impaired small intestinal motility and SIBO. In addition, further study has been limited by the technical challenges and lack of widespread availability of antroduodenal manometry. The development of a wireless motility capsule (WMC) (SmartPill) that evaluates pressure, pH, and temperature throughout the GI tract offers the potential to identify patients with small bowel transit delays who may be at risk for bacterial overgrowth.

AIMS

The primary aims of this study were to: (1) characterize the relationship of prolonged small bowel transit time (SBTT) in patients undergoing WMC with SIBO as based on a positive lactulose breath testing (LBT); and (2) to assess the relationship of prolonged gastric, colonic, and whole gut transit times (WGTT) and additional motility parameters with SIBO (positive LBT). We also sought to evaluate the relationship of small bowel motility parameters (SB motility index, contractions per minute, and SB peak amplitudes) with LBT results.

METHODS

We performed a retrospective study of consecutive patients who were referred for wireless motility testing at a single, tertiary care institution from April 2009 to December 2012. Of the 72 total patients identified, 34 underwent both WMC and LBT. Gastric, small bowel, colonic, WGTT, and SB motility parameters were measured and correlated with LBT results. Statistical methods utilized for data analysis include ANOVA, 2-sample t tests, nonparametric Kruskal Wallis test, Wilcoxon rank-sum test, and the Fisher exact test.

RESULTS

Of the 37 patients who underwent both WMC and LBT, 24 (65%) were LBT positive. The mean SBTT among those who were LBT positive was 6.6 hours as compared with 4.2 hours in those who were LBT negative (P=0.04). Among patients who were LBT positive, 47.6% had prolonged SBTT (≥6 h), whereas only 7.7% of those who were LBT negative had a delay in their SBTT (P=0.01). In addition, patients who were LBT positive were more likely to have prolongation of both colonic and WGTT versus those who were LBT negative (CTT: positive LBT=64.4 h vs. negative LBT=35.5 h, P=0.02; WGTT: positive LBT=70.5 h vs. negative LBT=44.1 h, P=0.02). However, there were no statistical differences observed between the groups for gastric emptying times or other small intestinal motility parameters (SB motility index, contractions per minute, and peak amplitudes) between the 2 groups.

CONCLUSIONS

Patients with underlying SIBO have significant delays in SBTT as compared with those without. The association between prolonged SBTT and positive LBT may be useful in identifying those patients with SIBO diagnosed by LBT and potentially target therapeutic options for those refractory to standard therapy. Interestingly, patients with positive LBT did not necessarily have a generalized gastrointestinal motility (similar GETs among groups), suggesting that small bowel transit specifically predisposes to the development of SIBO. Future, prospective studies are needed to further characterize intestinal dysmotility and other contributing pathophysiological mechanisms in SIBO and to investigate the potential benefits of prokinetics in this challenging patient population.

Gastrointestinal motility and neurogastroenterology

Nordic research on gastrointestinal motility has since 1965 made substantial contributions to our current understanding of gastrointestinal function. During the last decade, the term neurogastroenterology has widened the concept of motility research into the study of gastrointestinal sensory-motor function, including the complex central nervous system interaction. The discovery of a non-adrenergic non-cholinergic (NANC) innervation of the gut in the sixties was made by considerable contributions from the Nordic countries with the Martinson group in Sweden as central innovators. Important discoveries regarding the intramural nerve ganglia as mediators of the autonomic nervous input has also been produced from this research. In clinical motility research, the study of the migrating motor complex in the small bowel has revealed its ability to act as a retroperistaltic pump in the proximal duodenum (Sweden) and its important role for gut microbial homeostasis (Norway). Also in the development of methodology to study gut sensory-motor function, the Nordic countries has contributed. Examples are the physical characteristics of the esophageal manometry catheter (Denmark), the use of ultrasound for assessment of gastric function (Norway), a temporary electrical stimulation method in patients with severe nausea and vomiting (Sweden), a rectal barostat method for clinical evaluation of recto-anal function and a colonic transit time method utilizing radio-opaque markers (Sweden). In later years, the research collaborations have increasingly become worldwide in a manner making it less easy to define pure Nordic contributions.

Lactobacillus paracasei F19 versus placebo for the prevention of proton pump inhibitor-induced bowel symptoms: a randomized clinical trial

BACKGROUND

Proton pump inhibitors may foster intestinal dysbiosis and related bowel symptoms.

AIM

To evaluate the effect of Lactobacillus paracasei F19 on bowel symptom onset in patients on long-term proton pump inhibitors.

METHODS

In this randomized, double-blind, placebo-controlled study, patients with typical gastroesophageal reflux disease symptoms receiving pantoprazole 40 mg/d for six months were randomly assigned to receive: (A) Lactobacillus paracasei F19 bid for three days/week for six months; (B) placebo bid for three days/week for six months; (C) Lactobacillus paracasei F19 bid for three days/week for three months and placebo bid for three days/week for the following three months; (D) placebo bid for three days/week for three months and Lactobacillus paracasei F19 bid for three days/week for the following three months. Bloating, flatulence, abdominal pain and bowel habit were assessed monthly.

RESULTS

100/312 patients were enrolled. In the parallel groups, the treatment-by-time interaction affected bloating (p = 0.015), while Lactobacillus paracasei F19 treatment alone affected flatulence (p = 0.011). Moreover, the treatment-by-time interaction significantly affected the mean score of bloating (p = 0.01) and flatulence (p < 0.0001), the mean stool form (p = 0.03) and mean stool frequency/week (p = 0.016). Analysis of the cross-over groups, limited to the first three months because of carry-over effect, confirmed these results.

CONCLUSION

Lactobacillus paracasei F19 supplementation prevents bowel symptom onset in patients on long-term proton pump inhibitors.

Prevention of pelvic radiation disease

Pelvic cancers are among the most frequently diagnosed cancers worldwide. Treatment of patients requires a multidisciplinary approach that frequently includes radiotherapy. Gastrointestinal (GI) radiation-induced toxicity is a major complication and the transient or long-term problems, ranging from mild to very severe, arising in non-cancerous tissues resulting from radiation treatment to a tumor of pelvic origin, are actually called as pelvic radiation disease. The incidence of pelvic radiation disease changes according to the radiation technique, the length of follow up, the assessment method, the type and stage of cancer and several other variables. Notably, even with the most recent radiation techniques, i.e., intensity-modulated radiotherapy, the incidence of radiation-induced GI side effects is overall reduced but still not negligible. In addition, radiation-induced GI side effects can develop even after several decades; therefore, the improvement of patient life expectancy will unavoidably increase the risk of developing radiation-induced complications. Once developed, the management of pelvic radiation disease may be challenging. Therefore, the prevention of radiation-induced toxicity represents a reasonable way to avoid a dramatic drop of the quality of life of these patients. In the current manuscript we provide an updated and practical review on the best available evidences in the field of the prevention of pelvic radiation disease.

Pediatric small intestine bacterial overgrowth in low-income countries

Small intestine bacterial overgrowth (SIBO) occurs when colonic quantities of commensal bacteria are present in the small bowel. SIBO is associated with conditions of disrupted gastrointestinal (GI) motility leading to stasis of luminal contents. Recent data show that SIBO is also found in children living in unsanitary conditions who do not have access to clean water. SIBO leads to impaired micronutrient absorption and increased GI permeability, both of which may contribute to growth stunting in children. SIBO also disrupts mucosal immunity and has been implicated in oral vaccination underperformance and the development of celiac disease. SIBO in the setting of the impoverished human habitats may be an under-recognized cause of pediatric morbidity and mortality in the developing world.

Microbiota and radiation-induced bowel toxicity: lessons from inflammatory bowel disease for the radiation oncologist

New gastrointestinal symptoms are frequent after pelvic radiotherapy and can greatly affect the quality of life of cancer survivors. The effect of radiation on the intestinal microbiota, and the clinical implications of a modified microbial balance after radiotherapy are now beginning to emerge. In this Personal View, we show the importance of the microbiota for intestinal homoeostasis, and discuss the similarity between inflammatory bowel disease, which has been extensively researched, and radiation-induced gastrointestinal toxicity. By use of microbiota profiles for risk assessment and manipulation of the intestinal flora for prevention and treatment of radiation, enteropathy could become a reality and would be of substantial relevance to the increasing numbers of long-term cancer survivors.

Radiation-induced small bowel disease: latest developments and clinical guidance

Ionizing radiation is commonly used to treat a number of malignancies. Although highly effective and now more targeted, many patients suffer side effects. The number of cancer survivors has increased and so there are more patients presenting with symptoms that have arisen as a result of radiotherapy. Radiation damage to small bowel tissue can cause acute or chronic radiation enteritis producing symptoms such as pain, bloating, nausea, faecal urgency, diarrhoea and rectal bleeding which can have a significant impact on patient's quality of life. This review outlines the pathogenesis of radiation injury to the small bowel along with the prevention of radiation damage via radiotherapy techniques plus medications such as angiotensin-converting enzyme inhibitors, statins and probiotics. It also covers the treatment of both acute and chronic radiation enteritis via a variety of medical (including hyperbaric oxygen), dietetic, endoscopic and surgical therapies.

Impact of pelvic radiotherapy on gut microbiota of gynecological cancer patients revealed by massive pyrosequencing

Although pelvic irradiation is effective for the treatment of various cancer types, many patients who receive radiotherapy experience serious complications. Gut microbial dysbiosis was hypothesized to be related to the occurrence of radiation-induced complications in cancer patients. Given the lack of clinical or experimental data on the impact of radiation on gut microbiota, a prospective observational study of gut microbiota was performed in gynecological cancer patients receiving pelvic radiotherapy. In the current study, the overall composition and alteration of gut microbiota in cancer patients receiving radiation were investigated by 454 pyrosequencing. Gut microbial composition showed significant differences (P < 0.001) between cancer patients and healthy individuals. The numbers of species-level taxa were severely reduced after radiotherapy (P < 0.045), and the abundance of each community largely changed. In particular, the phyla Firmicutes and Fusobacterium were significantly decreased by 10% and increased by 3% after radiation therapy, respectively. In addition, overall gut microbial composition was gradually remolded after the full treatment course of pelvic radiotherapy. In this set of cancer patients, dysbiosis of the gut microbiota was linked to health status, and the gut microbiota was influenced by pelvic radiotherapy. Although further studies are needed to elucidate the relationship between dysbiosis and complications induced by pelvic radiotherapy, the current study may offer insights into the treatment of cancer patients suffering from complications after radiation therapy.

Probiotic bacteria in cancer patients undergoing chemotherapy and radiation therapy

BACKGROUND

Probiotics are live microorganisms, which as drugs or food supplements help to maintain health beneficial microbial balance in the digestive tract of a human or other host. Probiotics by their properties may help strengthen homeostasis and thus reduce side effects associated with cancer treatment. Experimental evidence suggests that probiotics might have beneficial effect on the toxicity of anticancer therapy.

METHODS

A computer-based literature search was carried out using PubMed (keywords: "probiotic" and "lactic acid bacteria" in association with the search terms "cancer" or "oncology" or "chemotherapy" or "radiation"); data reported at international meetings were included.

RESULTS

Probiotics might have beneficial effects on some aspects of toxicity related to anticancer treatment especially radiation therapy. However, reported trials vary in utilized probiotic strains, dose of probiotics and vast majority of them are small trials with substantial risk of bias. Despite limited data, it seems that probiotic bacteria as live microorganisms could be safely administered even in the setting of neutropenia.

CONCLUSIONS

Current evidence supporting probiotic use as adjunctive therapy to anticancer treatment is limited, especially in cancer patients treated with chemotherapy. Well designed clinical trials are needed to find true role of probiotics in oncology.

Systematic review: the efficacy of nutritional interventions to counteract acute gastrointestinal toxicity during therapeutic pelvic radiotherapy

BACKGROUND

Radiotherapy-induced damage to noncancerous gastrointestinal mucosa has effects on secretory and absorptive functions and can interfere with normal gastrointestinal physiology. Nutrient absorption and digestion may be compromised. Dietary manipulation is an attractive option for the prevention and management of symptoms.

AIM

To synthesise the evidence for the use of elemental formula low- or modified-fat diets, fibre, lactose restriction and probiotics, prebiotics and synbiotics to protect the gastrointestinal tract during pelvic radiotherapy.

METHODS

Four electronic databases were searched. Randomised controlled trials (RCT), controlled trials (CT) and case series in adult patients receiving radiotherapy for pelvic cancers employing nutritional interventions to reduce gastrointestinal toxicity were included. Methodological quality was assessed using a bespoke tool.

RESULTS

Twenty-two original studies (2446 patients) were identified. Study quality was highly variable with only 37% scoring ≥10 points (maximum 17: bespoke scale). Few studies assessed compliance with the intervention. End-points varied and included symptom scales (IBDQ, CTC, Bristol Stool and RTOG). Evidence from RCTs was weak for elemental, low- or modified-fat, fibre and low-lactose interventions with 1/4, 3/4, 1/2, 0/1 trials respectively reporting favourable outcomes. Evidence for probiotics as prophylactic interventions was more promising (4/5 favourable), but dose, strains and methodologies varied.

CONCLUSIONS

There is insufficient high-grade evidence to recommend nutritional intervention during pelvic radiotherapy. Total replacement of diet with elemental formula may be appropriate in severe toxicity. Probiotics offer promise, but cannot be introduced into clinical practice without rigorous safety analysis, not least in immunocompromised patients. The methodological quality of nutritional intervention studies needs to be improved.

Dysmotility and proton pump inhibitor use are independent risk factors for small intestinal bacterial and/or fungal overgrowth

BACKGROUND

Whether intestinal dysmotility and the use of a proton pump inhibitor (PPI) either independently or together contributes to small intestinal bacterial overgrowth (SIBO), and/or small intestinal fungal overgrowth (SIFO) is not known.

AIM

To investigate the role of dysmotility and PPI use in patients with persistent gastrointestinal complaints.

METHODS

Patients with unexplained gastrointestinal symptoms and negative endoscopy/radiology tests completed a validated symptom questionnaire and underwent 24-h ambulatory antro-duodeno-jejunal manometry (ADJM). Simultaneously, duodenal aspirate was obtained for aerobic, anaerobic and fungal culture. Dysmotility was diagnosed by (>2): absent phase III MMC, absent/diminished postprandial response, diminished amplitude of antral/intestinal phasic activity, impaired antro-duodenal coordination. Bacterial growth ≥10³ CFU/mL or fungal growth was considered evidence for SIBO/SIFO. PPI use was documented. Correlation of symptoms with presence of SIBO or SIFO was assessed.

RESULTS

One hundred and fifty subjects (M/F = 47/103) were evaluated; 94/150 (63%) had overgrowth: 38/94 (40%) had SIBO, 24/94 (26%) had SIFO and 32/94 (34%) had mixed SIBO/SIFO. SIBO was predominately due to Streptococcus, Enterococcus, Klebsiella and E. coli. SIFO was due to Candida. Eighty of 150 (53%) patients had dysmotility and 65/150 (43%) used PPI. PPI use (P = 0.0063) and dysmotility (P = 0.0003) were independent significant risk factors (P < 0.05) for overgrowth, but together did not pose additional risk. Symptom profiles were similar between those with or without SIBO/SIFO.

CONCLUSIONS

Dysmotility and PPI use were independent risk factors for SIBO or SIFO and were present in over 50% of subjects with unexplained gastrointestinal symptoms. Diagnosis of overgrowth requires testing because symptoms were poor predictors of overgrowth.

A retrospective identification of gastroesophageal reflux disease as a new risk factor for surgical site infection in cerebral palsy patients after spine surgery

BACKGROUND

Neuromuscular scoliosis is a known risk factor for surgical site infection (SSI) after spinal fusion, with reported infection rates as high as 11.2%. Although risk factors such as antibiotic timing have been previously addressed, our objective was to identify intrinsic risk factors for SSI in cerebral palsy (CP) patients with neuromuscular scoliosis. We hypothesized that CP patients who develop SSI after spine fusion would have a risk profile similar to those who develop nosocomial infection.

METHODS

We retrospectively analyzed records from patients with CP who developed infections after spinal fusion from January 1998 until July 2008, who were identified by our Infection Control Officer using National Nosocomial Infection Surveillance System criteria (N = 34). Demographically and procedurally matched controls without infection were identified from our spine database (N = 37). We compared these groups for gastroesophageal reflux disease (GERD), use of gastric acid inhibitors, presence of preoperative decubitus ulcer, previous infection, and postoperative ventilation. Multivariable logistic regression was then performed to assess the relative contributions of the predictors to "deep infection" and "any infection."

RESULTS

Of 30 evaluable infected patients, 70% had incisional SSI. Although many of the infections were polymicrobial, the most common pathogens identified were Gram-negative bacilli. Many significant predictors were identified by univariable logistic regression for any infection and deep infection. Multivariable logistic regression found a significant effect only for GERD (odds ratio, 6.4; 95% confidence interval, 1.9-21.3; P = 0.002) for any infection, whereas the effect of therapy with gastric acid inhibitors did not reach statistical significance (odds ratio, 6.1 [95% confidence interval, 0.84-44.6]; P = 0.07). No significant interaction between the 2 factors was detected. Among our controls and infected patients altogether, 46.3% had GERD.

CONCLUSIONS

We show that GERD increases the risk for infection in CP patients after spine fusion. Prospective multicenter studies are necessary to further validate the predictive value of this risk factor.

Managing gastrointestinal symptoms after cancer treatment: a practical approach for gastroenterologists

The percentage of the population living with a diagnosis of cancer is rising. By 2030, there will be 4 million cancer survivors in the UK. One quarter of cancer survivors are left with physical symptoms, which affect their quality of life. Gastrointestinal (GI) symptoms are the most common of all chronic physical side-effects of cancer treatment and have the greatest impact on daily activity. Cancer therapies induce long-term changes in bowel function due to alterations to specific GI physiological functions. In addition, the psychological effect of a cancer diagnosis, new GI disease or pre-existing underlying conditions, may also contribute to new symptoms. Twenty-three upper GI symptoms have been identified as occurring after pelvic radiotherapy. After upper GI cancer treatment, the most troublesome symptoms include reflux, abdominal pain, indigestion, diarrhoea and fatigue. Often, several symptoms are present simultaneously and women experience more symptoms than men. The symptoms which patients rate as most difficult are urgency, wind, diarrhoea, incontinence, abdominal pain and rectal bleeding. Recent UK Guidance on managing GI symptoms suggests that these symptoms can be treated especially if gastroenterological advice is combined with dietetic and nursing input to optimise investigations and management. However, as different pathological processes can result in identical symptoms; a systematic, 'algorithmic' approach to assess and treat these symptoms is required. This paper aims to illustrate the value of such an approach to investigate and treat the most common GI symptoms that trouble patients. The algorithm allows clinicians to institute a comprehensive medical management plan.

Quantitative analysis of intestinal gas in patients with acute pancreatitis

BACKGROUND

Disturbance of gastrointestinal function is a common complication in the early phase of acute pancreatitis (AP). Intestinal gas may reflect the function of the gut. Using plain abdominal radiographs, we investigated whether intestinal gas volume is related to AP.

METHODS

Plain abdominal radiographs of 68 patients with AP within 24 hours after admission and 21 normal controls were digitized and transmitted to a computer. The region of intestinal gas was identified by an image manipulation software and the gas volume score (GVS) was calculated. The relationships between the GVS values and various clinical factors of AP were analyzed.

RESULTS

The GVS in the AP group was 0.084+/-0.016, in the mild AP (MAP) group 0.070+/-0.005, and in the severe AP (SAP) group 0.094+/-0.013; all values were higher than that in the control group (P<0.01). The GVS in the SAP group was higher than that in the MAP group. The GVSs were correlated to the Ranson's scores (r=0.762, P<0.01) and the acute physiology and chronic health evaluation II (APACHE II) scores (r=0.801, P<0.01). In addition, the GVS in patients with secondary pancreatic and/or peripancreatic infection was 0.107+/-0.014, higher than that in patients without secondary infection (P<0.01). GVS was not related to gender, age, etiology or clinical outcome of AP.

CONCLUSIONS

Intestinal gas volume is significantly elevated in patients with AP. It is closely related to Ranson's and APACHE II score and secondary pancreatic and/or peripancreatic infection. GVS may be a new prognostic tool for assessing the severity of AP in the early course of the disease.

Small intestinal malabsorption in chronic alcoholism: a retrospective study of alcoholic patients by the ¹⁴C-D-xylose breath test

OBJECTIVE

The ¹⁴C-D-xylose breath test was used at Ullevål University Hospital in the period from 1986 TO 1995 for malabsorption testing. The objective of this retrospective study was to reveal whether patients with chronic alcoholism may have intestinal malabsorption.

MATERIALS AND METHODS

The consecutive ¹⁴C-D-xylose breath test database was reviewed and patients with the diagnosis of chronic alcoholism were identified. ¹⁴C-D-xylose breath test results of the alcoholic patients were compared with the results of untreated celiac patients and patient and healthy controls. In the ¹⁴C-D-xylose breath test, ¹⁴C-D-xylose was dissolved in water and given orally after overnight fast. Breath samples were taken at 30-min intervals for 210 min, and ¹⁴CO₂ : ¹²CO₂ ratios were calculated for each time point, presenting a time curve for ¹⁴C-D-xylose absorption. Urine was collected after 210 min and the fraction of the total d-xylose passed was calculated (U%). ¹⁴CO₂ in breath and ¹⁴C-D-xylose in urine were analyzed using liquid scintillation.

RESULTS

Both breath and urine analysis revealed a pattern of malabsorption in alcoholics comparable with untreated celiac patients, with significantly reduced absorption of d-xylose compared with patient and healthy controls.

CONCLUSION

Alcoholic patients have a significantly reduced ¹⁴C-D-xylose absorption, comparable with untreated celiac patients. This indicates a reduced intestinal function in chronic alcoholism.

The migrating motor complex: control mechanisms and its role in health and disease

The migrating motor complex (MMC) is a cyclic, recurring motility pattern that occurs in the stomach and small bowel during fasting; it is interrupted by feeding. The MMC is present in the gastrointestinal tract of many species, including humans. The complex can be subdivided into four phases, of which phase III is the most active, with a burst of contractions originating from the antrum or duodenum and migrating distally. Control of the MMC is complex. Phase III of the MMC with an antral origin can be induced in humans through intravenous administration of motilin, erythromycin or ghrelin, whereas administration of serotonin or somatostatin induces phase III activity with duodenal origin. The role of the vagus nerve in control of the MMC seems to be restricted to the stomach, as vagotomy abolishes the motor activity in the stomach, but leaves the periodic activity in the small bowel intact. The physiological role of the MMC is incompletely understood, but its absence has been associated with gastroparesis, intestinal pseudo-obstruction and small intestinal bacterial overgrowth. Measuring the motility of the gastrointestinal tract can be important for the diagnosis of gastrointestinal disorders. In this Review we summarize current knowledge of the MMC, especially its role in health and disease.

ICRP publication 118: ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs--threshold doses for tissue reactions in a radiation protection context

This report provides a review of early and late effects of radiation in normal tissues and organs with respect to radiation protection. It was instigated following a recommendation in Publication 103 (ICRP, 2007), and it provides updated estimates of 'practical' threshold doses for tissue injury defined at the level of 1% incidence. Estimates are given for morbidity and mortality endpoints in all organ systems following acute, fractionated, or chronic exposure. The organ systems comprise the haematopoietic, immune, reproductive, circulatory, respiratory, musculoskeletal, endocrine, and nervous systems; the digestive and urinary tracts; the skin; and the eye. Particular attention is paid to circulatory disease and cataracts because of recent evidence of higher incidences of injury than expected after lower doses; hence, threshold doses appear to be lower than previously considered. This is largely because of the increasing incidences with increasing times after exposure. In the context of protection, it is the threshold doses for very long follow-up times that are the most relevant for workers and the public; for example, the atomic bomb survivors with 40-50years of follow-up. Radiotherapy data generally apply for shorter follow-up times because of competing causes of death in cancer patients, and hence the risks of radiation-induced circulatory disease at those earlier times are lower. A variety of biological response modifiers have been used to help reduce late reactions in many tissues. These include antioxidants, radical scavengers, inhibitors of apoptosis, anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, growth factors, and cytokines. In many cases, these give dose modification factors of 1.1-1.2, and in a few cases 1.5-2, indicating the potential for increasing threshold doses in known exposure cases. In contrast, there are agents that enhance radiation responses, notably other cytotoxic agents such as antimetabolites, alkylating agents, anti-angiogenic drugs, and antibiotics, as well as genetic and comorbidity factors. Most tissues show a sparing effect of dose fractionation, so that total doses for a given endpoint are higher if the dose is fractionated rather than when given as a single dose. However, for reactions manifesting very late after low total doses, particularly for cataracts and circulatory disease, it appears that the rate of dose delivery does not modify the low incidence. This implies that the injury in these cases and at these low dose levels is caused by single-hit irreparable-type events. For these two tissues, a threshold dose of 0.5Gy is proposed herein for practical purposes, irrespective of the rate of dose delivery, and future studies may elucidate this judgement further.

Medical management of motility disorders in patients with intestinal failure: a focus on necrotizing enterocolitis, gastroschisis, and intestinal atresia

BACKGROUND

Intestinal failure (IF) is the dependence upon parenteral nutrition to maintain minimal energy requirements for growth and development. It may occur secondary to a loss of bowel length, disorders of motility, or both. Short bowel syndrome (SBS) is a malabsorptive state resulting from surgical resection, congenital defect, or diseases associated with loss of absorptive surface area. A particularly vexing problem is associated with whole bowel and/or segmental intestinal dysmotility. Motility disorders within the context of SBS and IF may relate to rapid intestinal transit secondary to loss of intestinal length, dysmotility associated with loss or poor antegrade peristalsis, or gastroparesis. Therapy may be classified into medical (prokinetic and antidiarrheal agents) and surgical to deal with the overdistended poorly motile bowel.

METHODS

We performed a systematic review of the literature pertaining to IF, SBS, and dysmotility in the pediatric population with gastroschisis, necrotizing enterocolitis, and intestinal atresia. In addition to the available treatment options, we have provided a review of the literature and a summary of the available evidence.

CONCLUSION

Despite relatively poor level of evidence regarding the application of promotility and antidiarrheal medications in patients with SBS and IF, these agents continue to be used. Herein, we provide a review of the physiology and pathophysiology of intestinal motility/dysmotility and available strategies for the use of promotility and antidiarrheal agents in patients with IF/SBS.

Meaningful or redundant complexity - mechanisms behind cyclic changes in gastroduodenal pH in the fasting state

The antroduodenal region is probably the site of the most common chronic infection of mankind, helicobacter-induced antral gastritis. After meals, the remaining gastric contents are evacuated by an interdigestive motor programme, the so-called migrating motor complex (MMC). The most characteristic feature of the MMC is phase III, a series of contractions at slow wave frequency (3 min⁻¹ in the stomach, approx. 12 min⁻¹ in the duodenum). Phase III is associated with complex changes in antroduodenal pH, the most prominent feature being a rapid alkalinization of the antral lumen immediately after the end of antral phase III. Before and during antral phase III (late phase II), gastric acid secretion increases and reflux of bile-containing fluid from the duodenum frequently occurs. At the start of duodenal phase III, the pacemaker driving the motor waves is located proximally in the contracting segment, and the motor waves are uniformly antegrade. After passing the papilla, the pacemaker which is now in the middle of the contracting segment stops its migration and waves passing the papilla hence become retrograde. Bile is diverted into the gall bladder. Duodenal phase III activates electrogenic chloride and bicarbonate secretion and release of secretory IgA. During the second half of phase III, there is accordingly reflux of bile-free fluid, bicarbonate and secretory IgA containing fluid from the duodenum into the stomach. Possible physiological and pathophysiological implications of this complex system, in particular the role of the gastric mucus layer in antral Helicobacter infection, will be discussed.