A novel breath test for the non-invasive assessment of small intestinal mucosal injury following methotrexate administration in the rat

Mechanistic inference of the metabolic rates underlying [Formula: see text]C breath test curves

Carbon stable isotope breath tests offer new opportunities to better understand gastrointestinal function in health and disease. However, it is often not clear how to isolate information about a gastrointestinal or metabolic process of interest from a breath test curve, and it is generally unknown how well summary statistics from empirical curve fitting correlate with underlying biological rates. We developed a framework that can be used to make mechanistic inference about the metabolic rates underlying a 13C breath test curve, and we applied it to a pilot study of 13C-sucrose breath test in 20 healthy adults. Starting from a standard conceptual model of sucrose metabolism, we determined the structural and practical identifiability of the model, using algebra and profile likelihoods, respectively, and we used these results to develop a reduced, identifiable model as a function of a gamma-distributed process; a slower, rate-limiting process; and a scaling term related to the fraction of the substrate that is exhaled as opposed to sequestered or excreted through urine. We demonstrated how the identifiable model parameters impacted curve dynamics and how these parameters correlated with commonly used breath test summary measures. Our work develops a better understanding of how the underlying biological processes impact different aspect of 13C breath test curves, enhancing the clinical and research potential of these 13C breath tests.

Scent test using Caenorhabditis elegans to screen for early-stage pancreatic cancer

Although early detection and diagnosis are indispensable for improving the prognosis of patients with pancreatic cancer, both have yet to be achieved. Except for pancreatic cancer, other cancers have already been screened through scent tests using animals or microorganisms, including Caenorhabditis elegans. While such a method may greatly improve the prognosis of pancreatic cancer, no studies have investigated the same, mainly given the difficulty of collecting suitable samples from patients with early-stage pancreatic cancer. In this study, we organized a nationwide study group comprising high-volume centers throughout Japan to collect patients with very-early-stage pancreatic cancer (stage 0 or IA). We initially performed an open-label study involving 83 cases (stage 0–IV), with subsequent results showing significant differences after surgical removal in stage 0–IA (×10 dilution: p < 0.001; ×100 dilution: p < 0.001). Thereafter, a blinded study on 28 cases (11 patients with stage 0 or IA disease and 17 healthy volunteers) was conducted by comparing very-early-stage pancreatic cancer patients with healthy volunteers to determine whether C. elegans could detect the scent of cancer for the diagnosis of early-stage pancreatic cancer. Preoperative urine samples had a significantly higher chemotaxis index compared to postoperative samples in patients with pancreatic cancer [×10 dilution: p < 0.001, area under the receiver operating characteristic curve (AUC) = 0.845; ×100 dilution: p < 0.001, AUC = 0.820] and healthy volunteers (×10 dilution: p = 0.034; ×100 dilution: p = 0.088). Moreover, using the changes in preoperative and postoperative chemotaxis index, this method had a higher sensitivity for detecting early pancreatic cancer compared to existing diagnostic markers. The clinical application C. elegans for the early diagnosis of cancer can certainly be expected in the near future.

Breath 13CO2-evidence for a noninvasive biomarker to measure added refined sugar uptake

Increased consumption of added sucrose and high-fructose corn syrup in the human diet has been associated with increasing incidence of obesity and metabolic disease. There are currently no reliable, objective biomarkers for added sugar intake that could be used in individuals or population settings. ¹³C is a stable isotope of carbon, and measurement of blood ¹³C content has been proposed as a marker of added sugar consumption. This study aimed to determine if breath ¹³CO₂ could represent an alternative, noninvasive biomarker to monitor added sugar intake. We undertook retrospective analyses of eight preclinical and human ¹³C-breath studies to define baseline breath ¹³CO₂ characteristics. All samples were analyzed using isotope ratio mass spectrometry, and breath ¹³CO₂ was expressed as the delta value, δ expressed as parts per thousand (‰). All data are expressed as mean ± SEM, with statistical significance considered at P < 0.05. Breath δ¹³CO₂ was significantly elevated in a cumulative manner in rats and mice that consumed a diet containing at least 15% sucrose. Mice fed an American rodent chow diet containing 50% sucrose and 15% corn starch had a significantly higher breath δ¹³CO₂ compared with rodents consuming an Australian rodent chow diet. Furthermore, breath δ¹³CO₂ was significantly increased in a dose-dependent manner in humans that ingested a bolus dose of sucrose. These findings suggest application for baseline breath δ¹³CO₂ as a noninvasive biomarker for added sugar consumption, with broad application for longitudinal assessment of population sugar intake and obesity management strategies.NEW & NOTEWORTHY We have found that breath ¹³CO₂ is increased in rats and mice consuming diets high in sucrose. We also found that human breath ¹³CO₂ is increased in humans consuming increasing amounts of sucrose. Our collective findings suggest that breath ¹³CO₂ represents a potential marker of added dietary sugar consumption.

Stable Isotope Techniques for the Assessment of Host and Microbiota Response During Gastrointestinal Dysfunction

The International Atomic Energy Agency convened a technical meeting on environmental enteric dysfunction (EED) in Vienna (October 28-30, 2015; https://nucleus.iaea.org/HHW/Nutrition/EED_Technical_Meeting/index.html) to bring together international experts in the fields of EED, nutrition, and stable isotope technologies. Advances in stable isotope-labeling techniques open up new possibilities to improve our understanding of gastrointestinal dysfunction and the role of the microbiota in host health. In the context of EED, little is known about the role gut dysfunction may play in macro- and micronutrient bioavailability and requirements and what the consequences may be for nutritional status and linear growth. Stable isotope labeling techniques have been used to assess intestinal mucosal injury and barrier function, carbohydrate digestion and fermentation, protein-derived amino acid bioavailability and requirements, micronutrient bioavailability and to track microbe-microbe and microbe-host interactions at the single cell level. The noninvasive nature of stable isotope technologies potentially allow for low-hazard, field-deployable tests of gut dysfunction that are applicable across all age groups. The purpose of this review is to assess the state-of-the-art use of stable isotope technologies and to provide a perspective on where these technologies can be exploited to further our understanding of gut dysfunction in EED.

Oral Nucleotides Only Minimally Improve 5-Fluorouracil-Induced Mucositis in Rats

Chemotherapy-induced mucositis is characterized by inflammation and ulceration of the intestinal mucosa, compromising intestinal function. Exogenous nucleotides have been reported to repair the mucosa. The nucleotide preparation, Nucleoforce F0328 (Nucleoforce), was investigated for its potential to ameliorate intestinal mucositis in rats. Female Dark Agouti rats (n = 8/group) were gavaged once daily with Nucleoforce (175 mg/kg) or water from Days 0 to 8 and injected (i.p.) with 5-fluorouracil (5-FU; 150 mg/kg) or saline on Day 5. Histological parameters (disease severity, crypt depth, and villus height measurements) and myeloperoxidase activity were quantified. P < 0.05 was considered significant. Jejunal and ileal histological disease severity scores were significantly increased by 5-FU, compared to normal controls (P < 0.05). Nucleoforce treatment in 5-FU-injected rats significantly reduced jejunal and ileal disease severity compared to 5-FU controls (P < 0.05). In 5-FU-injected rats, jejunal and ileal villus heights and crypt depths were significantly decreased compared to 5-FU controls, with no additional Nucleoforce effect (P > 0.05). Intestinal myeloperoxidase activity was significantly elevated by 5-FU (8.8-fold), compared to normal controls (P < 0.05), which was not normalized by Nucleoforce treatment (P > 0.05). Nucleoforce only partially improved parameters associated with experimentally-induced mucositis. Future studies could investigate increased concentrations, more frequent administration, or protective microencapsulation delivery methods, to increase bioavailability.

A simple and inexpensive enteric-coated capsule for delivery of acid-labile macromolecules to the small intestine

Understanding the ecology of the gastrointestinal tract and the impact of the contents on the host mucosa is emerging as an important area for defining both wellness and susceptibility to disease. Targeted delivery of drugs to treat specific small intestinal disorders such as small bowel bacterial overgrowth and targeting molecules to interrogate or to deliver vaccines to the remote regions of the small intestine has proven difficult. There is an unmet need for methodologies to release probes/drugs to remote regions of the gastrointestinal tract in furthering our understanding of gut health and pathogenesis. In order to address this concern, we need to know how the regional delivery of a surrogate labeled test compound is handled and in turn, if delivered locally as a liquid or powder, the dynamics of its subsequent handling and metabolism. In the studies we report on in this paper, we chose (13)C sodium acetate ((13)C-acetate), which is a stable isotope probe that once absorbed in the small intestine can be readily measured non-invasively by collection and analysis of (13)CO2 in the breath. This would provide information of gastric emptying rates and an indication of the site of release and absorptive capacity. In a series of in vitro and in vivo pig experiments, we assessed the enteric-protective properties of a commercially available polymer EUDRAGIT(®) L100-55 on gelatin capsules and also on DRcaps(®). Test results demonstrated that DRcaps(®) coated with EUDRAGIT(®) L100-55 possessed enhanced enteric-protective properties, particularly in vivo. These studies add to the body of knowledge regarding gastric emptying in pigs and also begin the process of gathering specifications for the design of a simple and cost-effective enteric-coated capsule for delivery of acid-labile macromolecules to the small intestine.

Gastrointestinal Safety Pharmacology in Drug Discovery and Development

Although the basic structure of the gastrointestinal tract (GIT) is similar across species, there are significant differences in the anatomy, physiology, and biochemistry between humans and laboratory animals, which should be taken into account when conducting a gastrointestinal (GI) assessment. Historically, the percentage of cases of drug attrition associated with GI-related adverse effects is small; however, this incidence has increased over the last few years. Drug-related GI effects are very diverse, usually functional in nature, and not limited to a single pharmacological class. The most common GI signs are nausea and vomiting, diarrhea, constipation, and gastric ulceration. Despite being generally not life-threatening, they can greatly affect patient compliance and quality of life. There is therefore a real need for improved and/or more extensive GI screening of candidate drugs in preclinical development, which may help to better predict clinical effects. Models to identify drug effects on GI function cover GI motility, nausea and emesis liability, secretory function (mainly gastric secretion), and absorption aspects. Both in vitro and in vivo assessments are described in this chapter. Drug-induced effects on GI function can be assessed in stand-alone safety pharmacology studies or as endpoints integrated into toxicology studies. In silico approaches are also being developed, such as the gut-on-a-chip model, but await further optimization and validation before routine use in drug development. GI injuries are still in their infancy with regard to biomarkers, probably due to their greater diversity. Nevertheless, several potential blood, stool, and breath biomarkers have been investigated. However, additional validation studies are necessary to assess the relevance of these biomarkers and their predictive value for GI injuries.

Zinc-fortified oral rehydration solution improved intestinal permeability and small intestinal mucosal recovery

A randomized double-blind placebo-controlled study was conducted in children admitted to hospital with gastroenteritis (≥3 loose stools per day). All were treated for 5 days following admission with either zinc (Zn, 3 mg) or without Zn-fortified rice-based oral rehydration solution (ORS). (13)C-sucrose breath test (SBT) and intestinal permeability (lactulose/rhamnose or L/R ratio) were performed concurrently prior to commencement of ORS with or without Zn and at day 5 post-admission. There was a significant improvement in the SBT results in both the Zn-fortified group, median (5th-95th percentile) 2.1% (0.4% to 8.3%) versus 4.4% (0.4% to 10.4%), P < .05, and control group, 1.4% (0.1% to 5.4%) versus 4.3% (0.4% to 11.4%), P < .05, between the day of admission and day 5 post-admission. In the Zn-fortified group, there was also a significant improvement in L/R ratio between the day of admission and day 5 post-admission, 53.0 (19.5-90.6) versus 17.7 (13.4-83.2), P < .05. Low levels of Zn improved intestinal permeability but did not enhance short-term recovery following diarrheal illness.

Grape seed extract dose-responsively decreases disease severity in a rat model of mucositis; concomitantly enhancing chemotherapeutic effectiveness in colon cancer cells

OBJECTIVE

Mucositis is a serious disorder of the gastrointestinal tract that results from cancer chemotherapy. We investigated the effects of increasing grape seed extract doses on the severity of chemotherapy in a rat model and its coincident impact on chemotherapeutic effectiveness in colon cancer cells.

DESIGN

Female Dark Agouti rats were gavaged with grape seed extract (400-1000 mg/kg) or water (day 3-11) and were injected intraperitoneally with 5-Fluorouracil (150 mg/kg) or saline (control) on day 9 to induce mucositis. Daily metabolic data were collected and rats were sacrificed on day 12. Intestinal tissues were collected for histological and myeloperoxidase analyses. Caco-2 cell viability was examined in response to grape seed extract in combination with 5-Fluorouracil by 3-(4,5-Dimethylthiazol-2yl)-2,5-diphenyl-tetrazolium bromide) assay.

RESULTS

Compared with 5-Fluorouracil controls, grape seed extract (400-1000 mg/kg) significantly decreased the histological damage score (P<0.05) in the jejunum. Grape seed extract (1000 mg/kg) increased jejunal crypt depth by 25% (P<0.05) in 5-Fluorouracil treated rats compared to 5-Fluorouracil controls, and attenuated the 5-Fluorouracil -induced reduction of mucosal thickness (25%, P<0.05). Grape seed extract (600 mg/kg) decreased myeloperoxidase activity by 55% (P<0.01) compared to 5-Fluorouracil controls. Grape seed extract was more effective at ameliorating 5-Fluorouracil induced intestinal injury, with effects most pronounced in the proximal jejunum. Grape seed extract (10-25 ug/mL) significantly enhanced the growth-inhibitory effects of 5-Fluorouracil by 26% (P<0.05) in Caco-2 cells and was more potent than 5-Fluorouracil at 50-100 µg/mL.

CONCLUSION

Grape seed extract may represent a new therapeutic option to decrease the symptoms of intestinal mucositis while concurrently impacting on the viability of colon cancer cells.

Clinical and structural effects of traditional Chinese medicine and the herbal preparation, Iberogast, in a rat model of ulcerative colitis

Plant-sourced formulations such as Iberogast and the traditional Chinese medicine formulation, Cmed, purportedly possess anti-inflammatory and radical scavenging properties. We investigated Iberogast and Cmed, independently, for their potential to decrease the severity of the large bowel inflammatory disorder, ulcerative colitis. Sprague Dawley rats (n = 8/group) received daily 1 mL gavages (days 0-13) of water, Iberogast (100 μL/200 μL), or Cmed (10 mg/20 mg). Rats ingested 2% dextran sulfate sodium or water ad libitum for 7 days commencing on day 5. Dextran sulfate sodium administration increased disease activity index scores from days 6 to 12, compared with water controls (P < .05). On day 10, 200 μL Iberogast decreased disease activity index scores in colitic rats compared with colitic controls (P < .05). Neither Iberogast nor Cmed achieved statistical significance for daily metabolic parameters or colonic crypt depth. The therapeutic effects of Iberogast and Cmed were minimal in the colitis setting. Further studies of plant extracts are required investigating greater concentrations and alternative delivery systems.

Emu oil expedites small intestinal repair following 5-fluorouracil-induced mucositis in rats

Mucositis resulting from cancer chemotherapy is characterized by intestinal inflammation and ulceration. Previously, emu oil (EO) improved intestinal architecture (Br J Nutr, 2010) in a rat model of chemotherapy-induced mucositis. We investigated EO for its further potential to promote intestinal repair in this mucositis model. Female Dark Agouti rats (n = 8/group) were gavaged with water, olive oil (OO) or EO once daily (1 mL), injected with 5-fluorouracil (5-FU) or saline on day 5 and euthanized on day 8, 9, 10 or 11. Intestinal villus height (VH) and crypt depth (CD), neutral mucin-secreting goblet cell (GC) count, myeloperoxidase (MPO) activity and selected cytokines were quantified; P < 0.05 was considered significant. In 5-FU-injected rats, only EO administration significantly increased VH in the ileum (day 8), jejunum and jejunum-ileum junction (days 8 and 9) compared to 5-FU controls (P < 0.05). GC count was significantly reduced by 5-FU (jejunum: days 8 and 9; ileum: day 8; P < 0.05) and EO increased ileal GC on days 10 and 11 compared to 5-FU controls. MPO activity was significantly increased in jejunum (days 8 and 9) and ileum (day 8) following 5-FU injection, compared to normal controls (P < 0.05). Both EO and OO significantly reduced jejunal MPO on days 8 and 9; however, only EO decreased ileal MPO on day 8. Cytokine levels were not significantly affected by either oil or 5-FU administration at the day 8 time point. Promotion of repair from injury could represent a new mechanism of action for EO, suggesting potential as an adjunct to conventional treatment approaches for cancer management.

Biomarkers of small intestinal mucosal damage induced by chemotherapy: an emerging role for the 13C sucrose breath test

Gastrointestinal mucosal toxicity is extremely common following cytotoxic therapies. The alimentary mucosa is particularly susceptible to injury and dysfunction, leading to many debilitating complications. Despite much research, there is currently no single noninvasive biomarker to detect gut injury. Several biomarkers have been investigated in the context of gastrointestinal diseases, which may prove useful in the oncology arena. Identification of a biomarker that is easy to obtain and measure and that accurately identifies mucosal damage would allow for improved patient diagnosis of toxicities and for personalized treatment regimens. In this review, we highlight the effectiveness of urine and breath tests as potential clinically effective biomarkers, with significant focus placed on the emerging role of the carbon-13 sucrose breath test (13C SBT). The 13C SBT provides a simple, noninvasive, and integrated measure of gut function. The 13C SBT also has the potential to monitor gut function in the setting of cytotoxic therapy-induced mucositis, or in the assessment of the efficacy of antimucositis agents.

Emu oil reduces small intestinal inflammation in the absence of clinical improvement in a rat model of indomethacin-induced enteropathy

Nonsteroidal-anti-inflammatory-drug (NSAID) enteropathy is characterized by small intestinal damage and ulceration. Emu Oil (EO) has previously been reported to reduce intestinal inflammation. Aim. We investigated EO for its potential to attenuate NSAID-enteropathy in rats. Methods. Male Sprague Dawley rats (n = 10/group) were gavaged with Water, Olive Oil (OO), or EO (0.5 mL; days 0–12) and with 0.5 mL Water or the NSAID, Indomethacin (8 mg/kg; days 5–12) daily. Disease activity index (DAI), 13C-sucrose breath test (SBT), organ weights, intestinal damage severity (IDS), and myeloperoxidase (MPO) activity were assessed. P < 0.05 was considered significant. Results. In Indomethacin-treated rats, DAI was elevated (days 10–12) and SBT values (56%) and thymus weight (55%) were decreased, relative to normal controls. Indomethacin increased duodenum (68%), colon (24%), SI (48%), caecum (48%), liver (51%) and spleen (88%) weights, IDS scores, and MPO levels (jejunum: 195%, ileum: 104%) compared to normal controls. Jejunal MPO levels were decreased (64%) by both EO and OO, although only EO decreased ileal MPO (50%), compared to Indomethacin controls. Conclusions. EO reduced acute intestinal inflammation, whereas other parameters of Indomethacin-induced intestinal injury were not affected significantly. Increased EO dose and/or frequency of administration could potentially improve clinical efficacy.

Emu Oil: a novel therapeutic for disorders of the gastrointestinal tract?

Gastrointestinal diseases characterized by inflammation, including the inflammatory bowel diseases, chemotherapy-induced mucositis and non-steroidal anti-inflammatory drug-induced enteropathy, currently have variably effective treatment options, highlighting the need for novel therapeutic approaches. Recently, naturally-sourced agents including prebiotics, probiotics, plant-extracts and marine-derived oils known to possess anti-inflammatory and anti-oxidant properties have been investigated in vitro and in vivo. However, animal-derived oils are yet to be extensively tested. Emu Oil is extracted from the subcutaneous and retroperitoneal fat of the Emu, a flightless bird native to Australia, and predominantly comprises fatty acids. Despite the limited rigorous scientific studies conducted to date, with largely anecdotal claims, Emu Oil, when administered topically and orally, has been shown to possess significant anti-inflammatory properties in vivo. These include a CD-1 mouse model of croton oil-induced auricular inflammation, experimentally-induced polyarthritis and dextran sulfate sodium-induced colitis. Recently, Emu Oil has been demonstrated to endow partial protection against chemotherapy-induced mucositis, with early indications of improved intestinal repair. Emu Oil could therefore form the basis of an adjunct to conventional treatment approaches for inflammatory disorders affecting the gastrointestinal system.

Emu oil increases colonic crypt depth in a rat model of ulcerative colitis

BACKGROUND

Current treatments for the inflammatory bowel diseases, encompassing Crohn's disease and ulcerative colitis, are variably effective. Emu oil, extracted from emu fat, predominantly comprises fatty acids, with purported claims of anti-inflammatory properties.

AIM

We evaluated emu oil for its potential to ameliorate dextran sulphate sodium (DSS)-induced colitis in rats.

METHODS

Male Sprague-Dawley Rats were allocated to treatment groups (n = 8). Groups 1 and 2 consumed water and were gavaged (1 ml) daily with water (group 1) or emu oil (group 2) from days 0 to 10. Groups 3-6 ingested 2% DSS in the drinking water from days 5 to 10 and were gavaged from days 0 to 10 with water (group 3), 0.5 ml emu oil (group 4) or 1 ml emu oil (group 5). Group 6 received 1 ml emu oil after commencing DSS treatment (days 6-10). Disease activity index, metabolic parameters, (13)C-sucrose breath test, and histological colonic damage severity and crypt depth were assessed.

RESULTS

Emu oil in DSS-treated rats reduced colonic damage severity compared to DSS-controls (up to threefold; P < 0.001). In DSS-treated rats, crypts in the proximal colon were lengthened by 0.5 ml emu oil (373 ± 18 μm), compared with DSS-controls (302 ± 8 μm); whilst in the distal colon (DSS control: 271 ± 17 μm), crypt depth was greater following 0.5 ml emu oil (352 ± 22 μm) and 1 ml emu oil (341 ± 9 μm) and also when emu oil was administered post-DSS commencement (Group 6: 409 ± 16 μm; P < 0.05). Emu oil did not significantly affect other parameters of colonic architecture.

CONCLUSIONS

Emu oil improved tissue damage associated with colitis, suggesting its potential as a unique formulation to augment conventional treatment approaches for IBD.

Zinc homeostasis and gut function in children with celiac disease

BACKGROUND

Celiac disease (CD) is an immunologic enteropathy triggered by the intake of gluten. It is thought that the enteropathy impairs gut function and absorption.

OBJECTIVE

We assessed the zinc-absorption capacity and small-bowel integrity in children with CD.

DESIGN

Children in whom a diagnosis of CD was considered clinically and either confirmed (n = 16; Marsh score ≥3) or not (n = 22; Marsh score of 0) with a small-bowel biopsy (SBB) were recruited. The fractional absorption of zinc (FAZ) was determined by the administration of an oral (67)Zn dose (2.5 mg) and an intravenous (70)Zn dose (0.2 mg) 2 h before and during the SBB, respectively. Spot urine samples were collected, and zinc isotopic ratios were determined by ion-coupled plasma mass spectrometry. Gut health was assessed by the ingestion of (13)C-sucrose (20 g) after an overnight fast, and breath samples were collected and analyzed by isotope ratio mass spectrometry.

RESULTS

There was no difference in FAZ between children with a Marsh score ≥3 (mean ± SEM: 0.68 ± 0.05) and children with a Marsh score of 0 (0.74 ± 0.05). The exchangeable zinc pool (EZP) was significantly (P < 0.05) lower in children with a Marsh score ≥3 (2.6 ± 0.8 mg/kg) than in children with a Marsh score of 0 (3.8 ± 1.4 mg/kg). Gut function in children with a Marsh score ≥3 (4.5 ± 0.7% cumulative dose recovered at 90 min) was lower than the lower cutoff of a normal gut-function breath test (5.06% cumulative dose recovered at 90 min) but not significantly different from that in children with a Marsh score of 0 (4.9 ± 0.4%). There was a significant (P < 0.01) correlation between zinc absorption and gut function in children with CD.

CONCLUSIONS

Zinc absorption did not appear below usual amounts in subjects with CD. Children with CD have impaired gut function that may affect their zinc nutritional status as shown by a smaller EZP. However, the EZP decrease in children with CD was not compared with that in healthy control subjects, and its biological meaning is uncertain.

Biomarkers of regimen-related mucosal injury

Regimen-related mucosal toxicity is extremely common following cytotoxic chemotherapy and radiotherapy. The alimentary mucosa is particularly susceptible to injury and dysfunction, leading to a constellation of adverse side effects. Currently there is no "one fit" biomarker of such injury. A number of biomarkers have been investigated in the context of gastrointestinal diseases, which may prove useful in the oncology arena. Two of significant potential include citrulline and calprotectin, however more work is required to define the most appropriate settings for their use. Identification of a biomarker that is easily obtained, measured, and accurately indicates mucosal damage, would allow for improved patient diagnosis of toxicities and prompt appropriate intervention. In this review, we highlight the effectiveness of currently examined biomarkers and discuss future avenues for research in this exciting area.

Orally administered emu oil decreases acute inflammation and alters selected small intestinal parameters in a rat model of mucositis

Mucositis resulting from cancer chemotherapy is a serious disorder of the alimentary tract. Emu oil has demonstrated anti-inflammatory properties in animal models of arthritis and wound healing; however, its effects on the intestine remain unknown. We investigated emu oil for its potential to decrease the severity of mucositis in a rat model. Female Dark Agouti rats (110–150 g) were orogastrically gavaged with emu oil (0·5 or 1 ml) or water (1 ml) for 5 d before intraperitoneal injection of 5-fluorouracil (5-FU, 150 mg/kg) or saline (control), and this was continued up to the day of sacrifice (48, 72 and 96 h post 5-FU administration). Histological (villus height, crypt depth (CD) and disease severity score) and biochemical (myeloperoxidase (MPO) activity) parameters were determined in intestinal tissues collected at sacrifice. Sucrase activity in vivo was quantified by the sucrose breath test. Activated neutrophil activity (MPO) in the ileum was significantly decreased by emu oil (0·5 ml, 451 (sem 168) U/g and 1 ml, 503 (sem 213) U/g) compared with 5-FU-treated controls (1724 (sem 431) U/g) 96 h post 5-FU administration. There were also significant increases in CD (152 (sem 8) μm) in the ileum of rats that receivied 1 ml emu oil at 96 h compared with 5-FU-treated controls (CD (106 (sem 12) μm)). Emu oil did not affect sucrase activity. Emu oil decreased acute ileal inflammation, and improved mucosal architecture in the intestine during recovery from chemotherapy in rats. Further studies investigating the potential benefits of emu oil as a nutritional supplement for the treatment of intestinal disorders are indicated.

Optimization of the non-invasive 13C-sucrose breath test in a rat model of methotrexate-induced mucositis

PURPOSE

In order to determine the sensitivity and specificity of the test and to optimize experimental conditions utilizing the SBT in a rat model of chemotherapy-induced small intestinal damage.

METHODS

Initially, a 13C-sucrose dose-response study was performed in rats to determine an optimal sucrose concentration for the SBT; then applied to assess chemotherapy-induced intestinal damage. A further study was conducted to establish a SBT time-course of methotrexate-induced small intestinal damage and repair. Animals were killed at 96 or 144 h.

RESULTS

A sucrose concentration of 0.25 g/ml was optimal (20% CV) for reproducibility and detection of intestinal damage. Maximal damage occurred at 72 h, small intestinal repair was initiated by 96 h and continued at 144 h post-MTX, as determined by the SBT and confirmed by biochemical analyses. Levels of sensitivity and specificity for the SBT were 98 and 94%, respectively.

CONCLUSIONS

The SBT is a reliable non-invasive marker of small intestinal health and damage with a high degree of sensitivity and specificity.

Small-intestinal manifestations of dextran sulfate sodium consumption in rats and assessment of the effects of Lactobacillus fermentum BR11

The dextran sulfate sodium (DSS) colitis model has been utilized to screen for novel therapeutics for ulcerative colitis. Evidence suggests the small intestine may also be affected by DSS. We characterized the effects of DSS on the small intestine and assessed the potential for Lactobacillus fermentum BR11 to modify or normalize DSS-induced changes. Rats were allocated to three groups, Water + Vehicle, DSS + Vehicle, and DSS + L. fermentum BR11. BR11 was administered twice daily for 14 days. DSS (2%) was provided from days 7 to 14. Small-intestinal tissue was analyzed for sucrase activity, histology, and crypt cell proliferation. Increased ileum crypt depth and cell proliferation was observed in DSS-treated rats compared to controls (P < 0.05). BR11 normalized these parameters. While DSS predominantly induces colonic damage, minor morphological alterations were also detected in the distal small intestine. L. fermentum BR11 normalized these features.

Lactobacillus fermentum BR11 and fructo-oligosaccharide partially reduce jejunal inflammation in a model of intestinal mucositis in rats

Although probiotics are beginning to enter mainstream medicine for disorders of the colon, their effects on the small bowel remain largely unexplored. We investigated the recently identified probiotic, Lactobacillus fermentum (L. fermentum) BR11 (BR11) and the prebiotic, fructo-oligosaccharide (FOS), both individually and in synbiotic combination, for their potential to alleviate intestinal mucositis. From Days 0-9, rats consumed skim milk (SM; saline + SM), low dose (LD-BR11; 1 x 10(6)cfu/ml), high dose (HD-BR11; 1 x 10(9)cfu/ml), LD-FOS (3%), HD-FOS (6%), or synbiotic (HD-BR11/FOS). On Day 7, rats were injected with 5-fluorouracil (5-FU; 150 mg/kg). All rats were sacrificed on Day 10. Intestinal tissues were collected for quantitative histology, sucrase, and myeloperoxidase (MPO) determinations. 5-FU decreased sucrase activity, villus height, crypt depth, and crypt cell proliferation compared to controls. Compared to 5-FU + SM, histological damage severity scores were increased for all treatments, although all were effective at reducing jejunal inflammation, indicated by reduced MPO activity (P < 0.05). The combination of BR11 and FOS did not provide additional protection. Moreover, HD-FOS and the synbiotic actually increased clinical mucositis severity (P < 0.05). We conclude that L. fermentum BR11 has the potential to reduce inflammation of the upper small intestine. However, its combination with FOS does not appear to confer any further therapeutic benefit for the alleviation of mucositis.

Yoghurts containing probiotics reduce disruption of the small intestinal barrier in methotrexate-treated rats

Small intestinal permeability was employed to assess the efficacy of commercially available yoghurts containing probiotics in a rat model of methotrexate (MTX)-induced mucositis. Male Sprague-Dawley rats were allocated to four groups (n = 8): MTX + water, MTX + cow's milk yoghurt (CY; fermented with Lactobacillus johnsonii), MTX + sheep's milk yoghurt (SY; containing Lactobacillus bulgaricus and Streptococcus thermophilus), and saline. Treatment gavage occurred twice daily for 7 days pre-MTX and 5 days post-MTX. Intestinal permeability was assessed on days -7, -1, 2, and 5 of the trial. Intestinal sections were collected at sacrifice for histological and biochemical analyses. Histology revealed that rats receiving CY and SY did not have a significantly damaged duodenum compared to controls. However, an improved small intestinal barrier function was evident, determined by a decreased lactulose/mannitol ratio. Probiotics containing SY and CY may be useful in preventing disruption to intestinal barrier function in MTX-induced mucositis.

Can emu oil ameliorate inflammatory disorders affecting the gastrointestinal system?

Emu oil possesses significant anti-inflammatory properties in vivo, primarily when applied topically. However, to date, the evidence supporting its therapeutic application has been largely anecdotal, and significant batch-to-batch variations in potency have been reported. Nevertheless, the anti-inflammatory properties of emu oil suggest therapeutic promise for the adjunctive treatment of a range of disparate gastrointestinal diseases and disorders characterised by inflammatory processes. These include the idiopathic condition inflammatory bowel disease, chemotherapy-induced mucositis, non-steroidal anti-inflammatory drug enteropathy and the various infective enteritides (i.e. fungal, bacterial and viral gastroenteritis). Although rigorous scientific investigations are in their infancy, the evidence for emu oil efficacy in extra-intestinal disorders, supported by limited in vivo investigations of other naturally sourced oils, identifies emu oil as a possible adjunct to conventional treatment approaches for inflammatory disorders affecting the gastrointestinal system.

Lactobacillus rhamnosus GG exacerbates intestinal ulceration in a model of indomethacin-induced enteropathy

Lactobacillus rhamnosus GG (LGG) and Bifidobacterium lactis Bb12 (Bb12) were assessed for their potential to prevent indomethacin-induced ulceration in the small intestine of Sprague-Dawley rats. Rats were gavaged skim milk, LGG, or Bb12 twice daily for 14 days. Between days 7-14, rats were gavaged indomethacin (Indo; 6 mg/kg). At sacrifice, small intestine was scored for ulceration and sampled for histologic, immunohistochemical, and myeloperoxidase (MPO) analyses. Indo+LGG-treated rats exhibited a 2.3-fold increase in MPO activity and a 9.8-fold increase in ulceration area compared to Indo-treated controls; these parameters did not differ significantly between Indo+Bb12 and Indo-treated controls. Crypt cell apoptosis decreased by 82% in Indo+Bb12-treated and 55% in Indo+LGG-treated rats compared to Indo-treated controls. Proliferation increased by 209% in Indo+LGG-treated animals compared to Indo-treated controls. Bb12 did not reduce indomethacin-induced intestinal ulceration, whereas LGG actually increased some indicators of injury. LGG and Bb12, at the doses tested, cannot alleviate indomethacin-induced intestinal injury.

Probiotic effects on 5-fluorouracil-induced mucositis assessed by the sucrose breath test in rats

The sucrose breath test (SBT) was employed to noninvasively assess the efficacy of probiotics in 5-fluorouracil (5-FU)-induced intestinal mucositis. Dark Agouti rats were allocated to 5 groups (n = 10): 5-FU + L. fermentum BR 11, 5-FU + L. rhamnosus GG, 5-FU + B. lactis BB 12, 5-FU + skim milk (SM), and saline + SM. Probiotics were administered by oral gavage for 10 days. Mucositis was induced on day 7 by intraperitoneal injection of 5-FU (150 mg/kg) or vehicle (saline). Rats were sacrificed 72 h after 5-FU injection. The SBT measured breath 13CO2 (expressed as percentage cumulative dose at 90 min; %CD90) on days 0, 7, and 10. %CD90 was significantly lower in 5-FU-treated controls compared with that in saline-treated controls on day 10. 5-FU caused an 83% reduction in sucrase and a 510% increase in MPO activity. The SBT detected damage induced by 5-FU and is a simple, noninvasive indicator of small bowel injury. The probiotics assessed offered no protection from mucositis at the dose tested.