Bugging the intestinal response to radiation

Development of a mouse model of radiation-induced duodenitis

AIM: To develop a mouse model of radiation-induced duodenitis.

METHODS: Ninety-three female Balb/c mice were randomly divided into seven groups: a control group (n = 13), a 4.5 Gy group (n = 13), a 6.0 Gy group (n = 13), a 9.0 Gy group (n = 13), a 12.0 Gy group (n = 13), a 13.5 Gy group (n = 13) and a 15.0 Gy group (n = 15). Mice were sacrificed 3.5 or 7.0 d after abdominal irradiation with a single dose of Cobalt-60. Duodenal samples were taken for histopathological analysis, and blood, spleen and mesenteric lymph nodes were sampled to detect the levels of inflammatory factors interleukin-6 (IL-6), IL-1β and tumor necrosis factor-α (TNF-α).

RESULTS: The levels of inflammatory factors IL-6, IL-1β and TNF-α increased in all the irradiation groups compared to the control group. The length of villi and the number of crypt were significantly reduced in the 12.0, 13.5 and 15.0 Gy groups compared to the control group on day 3.5, which was consistent with the changes in radiation-induced enteritis. The 13.5 and 15.0 Gy groups had a high mortality, and the 12.0 Gy group was better in simulating clinical radioactive duodenitis.

CONCLUSION: A mouse model of radiation-induced duodenitis can be successfully developed by abdominal irradiation with a single dose (12.0 Gy) of ⁶⁰Co.

Therapeutic effect and mechanism of Liangxueyuchang Decoction on acute radiation-induced enteritis in a rat model

AIM: To evaluate the therapeutic effect and mechanism of Liangxueyuchang Decoction on radiation-induced enteritis in a rat model.

METHODS: One hundred and fourteen SD rats were randomly divided into three groups. Group A (n = 18) underwent no treatment, while groups B (n = 48) and C (n = 48) underwent whole abdominal irradiation at a single dose of 10 Gy and 15 Gy, respectively. After irradiation, groups B and C were further divided into two subgroups. Subgroups B1 and C1 were intragastrically administered with distilled water, while subgroups B2 and C2 were intragastrically administered with Liangxueyuchang Decoction for 7 d from the first day after irradiation. The general condition and defecation in rats of all groups were observed every day. Samples from the jejunum, upper rectum and mesenteric lymph nodes were taken on days 2, 4, and 7 to examine pathological changes and calucate crypt survival rate. The rectum was evaluated microscopically using a scoring system and bacterial translocation was examined.

RESULTS: The general condition and defecation were better in subgroups B2 and C2 than in subgroups B1 and C1, especially on days 5-7. Pathological changes in the intestinal mucosa were milder in subgroups B2 and C2 than in subgroups B1 and C1. Crypt survival rate was improved on days 4 and 7 in subgroups B2 and C2 compared to subgroups B1 and C1 (F_d = 28.42,

F_f = 32.58, both P < 0.01). Rectal Hovdenak scores were higher in group C than in groups B and A, but were lower in subgroups B2 and C2 than in subgroups B1 and C1 (day 4: F = 5.26, 14.12; P < 0.05, P < 0.01). Bacterial translocation occurred after radiation in all groups, and the rate of bacterial translocation was significantly lower in subgroups B2 and C2 than in subgroups B1 and C1 (F = 6.48, 12.24; P < 0.05, P < 0.01).

CONCLUSION: Liangxueyuchang Decoction is effective in managing acute radiation-induced enteritis, and the therapeutic mechanism may be related to accelerating the recovery of injured intestinal mucosal epithelium, reducing bacterial translocation, and maintaining the normal structure and function of intestinal mucosa.

Effects of probiotics for the prevention and treatment of radiation-induced diarrhea

BACKGROUND AND AIMS

Probiotic supplementation seems to provide beneficial effects in the prevention and treatment of radiation-induced diarrhea. We performed a systematic review and meta-analysis to estimate the efficacy of probiotic supplementation for prevention and treatment of radiation-induced diarrhea.

METHODS

Two reviewers independently searched PubMed, EMBASE, Cochrane Library, Google Scholar and on-line clinical trials registers (up to January 2009) for randomized controlled trials that evaluated the efficacy of probiotic supplementation for the prevention and treatment of radiation-induced diarrhea. Each clinical trial was separately evaluated for study characteristics, methodologic quality and outcomes. Results of the randomized controlled trials were pooled in a meta-analysis.

RESULTS

Four randomized controlled trials were included. Three clinical trials, with a total of 632 subjects, evaluated the preventive effects of probiotic supplementation and 1 study evaluated the therapeutic role. Random effects meta-analysis of the preventive trials did not show significant differences between probiotic supplementation and control groups (odds ratio 0.47; 95% confidence interval: 0.13-1.67). However, the few available trials and the presence of significant clinical and statistical heterogeneity limited the analysis. Similarly, the therapeutic clinical trial did not show significant differences between active and placebo groups. No major adverse events owing to probiotic supplementation were reported in any study.

CONCLUSIONS

Probiotic supplementation showed beneficial effect in the prevention and treatment of radiation-induced diarrhea in experimental animal studies. Encouraging results have been observed in humans; however, the few available clinical studies do not allow firm conclusions. More well-performed, randomized placebo-controlled studies are needed.

Factors influencing intestinal microparticle uptake in vivo

The aim of this study is to compare microparticle uptake in animals of different ages, gender and species and at different time points. The 2mum latex/in vivo in situ model uses the observation of animal responses or post-mortem changes and also particle identification by fluorescence microscopy in nine sequential intestinal segments and secondary sites. The wide size range of animals studied requires particle numbers in tissue compartments to be related to intestinal tissue section area through a circumference measurement. Area under the curve (AUC) data for particles in intestinal tissue are plotted against measurements of intestinal length, allowing comparisons to be made across different ages and species and between males and females. The percentage uptake of administered dose and particle numbers in macerated tissue are also reported. Some parameters, in particular species, do not appear to affect the extent of microparticle uptake, which ranges from 0.12 to 0.32% of the administered dose. Particle uptake does, however, vary with age, being significantly greater in young adult males (7 weeks) than in younger (3 weeks) and older (17 and 52 weeks) age groups. It is concluded that age is more important in determining the extent of uptake than gender or species.