Butyrate enhances the efficacy of radiotherapy via FOXO3A in colorectal cancer patient­derived organoids.

Enhancing the radioresponsiveness of colorectal cancer (CRC) is essential for local control and prognosis. However, consequent damage to surrounding healthy cells can lead to treatment failure. We hypothesized that short­chain fatty acids (SCFAs) could act as radiosensitizers for cancer cells, allowing the administration of a lower and safer dose of radiation. To test this hypothesis, the responses of three­dimensional­cultured organoids, derived from CRC patients, to radiotherapy, as well as the effects of combined radiotherapy with the SCFAs butyrate, propionate and acetate as candidate radiosensitizers, were evaluated via reverse transcription­quantitative polymerase chain reaction, immunohistochemistry and organoid viability assay. Of the three SCFAs tested, only butyrate suppressed the proliferation of the organoids. Moreover, butyrate significantly enhanced radiation­induced cell death and enhanced treatment effects compared with administration of radiation alone. The radiation­butyrate combination reduced the proportion of Ki­67 (proliferation marker)­positive cells and decreased the number of S phase cells via FOXO3A. Meanwhile, 3/8 CRC organoids were found to be non­responsive to butyrate with lower expression levels of FOXO3A compared with the responsive cases. Notably, butyrate did not increase radiation­induced cell death and improved regeneration capacity after irradiation in normal organoids. These results suggest that butyrate could enhance the efficacy of radiotherapy while protecting the normal mucosa, thus highlighting a potential strategy for minimizing the associated toxicity of radiotherapy.

Resistant starch supplementation increases crypt cell proliferative state in the rectal mucosa of older healthy participants.

There is strong evidence that foods containing dietary fibre protect against colorectal cancer, resulting at least in part from its anti-proliferative properties. This study aimed to investigate the effects of supplementation with two non-digestible carbohydrates, resistant starch (RS) and polydextrose (PD), on crypt cell proliferative state (CCPS) in the macroscopically normal rectal mucosa of healthy individuals. We also investigated relationships between expression of regulators of apoptosis and of the cell cycle on markers of CCPS. Seventy-five healthy participants were supplemented with RS and/or PD or placebo for 50 d in a 2 × 2 factorial design in a randomised, double-blind, placebo-controlled trial (the Dietary Intervention, Stem cells and Colorectal Cancer (DISC) Study). CCPS was assessed, and the expression of regulators of the cell cycle and of apoptosis was measured by quantitative PCR in rectal mucosal biopsies. SCFA concentrations were quantified in faecal samples collected pre- and post-intervention. Supplementation with RS increased the total number of mitotic cells within the crypt by 60 % (P = 0·001) compared with placebo. This effect was limited to older participants (aged ≥50 years). No other differences were observed for the treatments with PD or RS as compared with their respective controls. PD did not influence any of the measured variables. RS, however, increased cell proliferation in the crypts of the macroscopically-normal rectum of older adults. Our findings suggest that the effects of RS on CCPS are not only dose, type of RS and health status-specific but are also influenced by age.

Chronically stimulated human MAIT cells are unexpectedly potent IL-13 producers.

Mucosal-associated invariant T (MAIT) cells are unconventional T cells that recognize antigens derived from riboflavin biosynthesis. In addition to anti-microbial functions, human MAIT cells are associated with cancers, autoimmunity, allergies and inflammatory disorders, although their role is poorly understood. Activated MAIT cells are well known for their rapid release of Th1 and Th17 cytokines, but we have discovered that chronic stimulation can also lead to potent interleukin (IL)-13 expression. We used RNA-seq and qRT-PCR to demonstrate high expression of the IL-13 gene in chronically stimulated MAIT cells, and directly identify IL-13 using intracellular flow cytometry and multiplex bead analysis of MAIT cell cultures. This unexpected finding has important implications for IL-13-dependent diseases, such as colorectal cancer (CRC), that occur in mucosal areas where MAIT cells are abundant. We identify MAIT cells near CRC tumors and show that these areas and precancerous polyps express high levels of the IL-13 receptor, which promotes tumor progression and metastasis. Our data suggest that MAIT cells have a more complicated role in CRC than currently realized and that they represent a promising new target for immunotherapies where IL-13 can be a critical factor.

Transcriptomics and proteomics show that selenium affects inflammation, cytoskeleton, and cancer pathways in human rectal biopsies.

Epidemiologic studies highlight the potential role of dietary selenium (Se) in colorectal cancer prevention. Our goal was to elucidate whether expression of factors crucial for colorectal homoeostasis is affected by physiologic differences in Se status. Using transcriptomics and proteomics followed by pathway analysis, we identified pathways affected by Se status in rectal biopsies from 22 healthy adults, including 11 controls with optimal status (mean plasma Se = 1.43 µM) and 11 subjects with suboptimal status (mean plasma Se = 0.86 µM). We observed that 254 genes and 26 proteins implicated in cancer (80%), immune function and inflammatory response (40%), cell growth and proliferation (70%), cellular movement, and cell death (50%) were differentially expressed between the 2 groups. Expression of 69 genes, including selenoproteins W1 and K, which are genes involved in cytoskeleton remodelling and transcription factor NFκB signaling, correlated significantly with Se status. Integrating proteomics and transcriptomics datasets revealed reduced inflammatory and immune responses and cytoskeleton remodelling in the suboptimal Se status group. This is the first study combining omics technologies to describe the impact of differences in Se status on colorectal expression patterns, revealing that suboptimal Se status could alter inflammatory signaling and cytoskeleton in human rectal mucosa and so influence cancer risk.-Méplan, C., Johnson, I. T., Polley, A. C. J., Cockell, S., Bradburn, D. M., Commane, D. M., Arasaradnam, R. P., Mulholland, F., Zupanic, A., Mathers, J. C., Hesketh, J. Transcriptomics and proteomics show that selenium affects inflammation, cytoskeleton, and cancer pathways in human rectal biopsies.

In vitro and ex vivo testing of tenofovir shows it is effective as an HIV-1 microbicide.

BACKGROUND: Tenofovir gel has entered into clinical trials for use as a topical microbicide to prevent HIV-1 infection but has no published data regarding pre-clinical testing using in vitro and ex vivo models. To validate our findings with on-going clinical trial results, we evaluated topical tenofovir gel for safety and efficacy. We also modeled systemic application of tenofovir for efficacy. METHODS AND FINDINGS: Formulation assessment of tenofovir gel included osmolality, viscosity, in vitro release, and permeability testing. Safety was evaluated by measuring the effect on the viability of vaginal flora, PBMCs, epithelial cells, and ectocervical and colorectal explant tissues. For efficacy testing, PBMCs were cultured with tenofovir or vehicle control gels and HIV-1 representing subtypes A, B, and C. Additionally, polarized ectocervical and colorectal explant cultures were treated apically with either gel. Tenofovir was added basolaterally to simulate systemic application. All tissues were challenged with HIV-1 applied apically. Infection was assessed by measuring p24 by ELISA on collected supernatants and immunohistochemistry for ectocervical explants. Formulation testing showed the tenofovir and vehicle control gels were >10 times isosmolar. Permeability through ectocervical tissue was variable but in all cases the receptor compartment drug concentration reached levels that inhibit HIV-1 infection in vitro. The gels were non-toxic toward vaginal flora, PBMCs, or epithelial cells. A transient reduction in epithelial monolayer integrity and epithelial fracture for ectocervical and colorectal explants was noted and likely due to the hyperosmolar nature of the formulation. Tenofovir gel prevented HIV-1 infection of PBMCs regardless of HIV-1 subtype. Topical and systemic tenofovir were effective at preventing HIV-1 infection of explant cultures. CONCLUSIONS: These studies provide a mechanism for pre-clinical prediction of safety and efficacy of formulated microbicides. Tenofovir was effective against HIV-1 infection in our algorithm. These data support the use of tenofovir for pre-exposure prophylaxis.

Thermally reversible in situ gelling carbamazepine liquid suppository.

Carbamazepine (CBZ), indicated for the control of epilepsy, undergoes extensive hepatic first-pass elimination after oral administration. A rectal dosage form of CBZ is not commercially available, although it is of particular interest when oral administration is impossible. Conventional suppositories can cause patient discomfort and may reach the end of the colon; consequently, the drug can undergo the first-pass effect. Mucoadhesive liquid suppositories of CBZ were prepared by adding carbopol to formulation of thermally gelling suppositories that contain 20% poloxamer 407 and either 15% poloxamer 188 or 1% methylcellulose. Gellan gum was also tried instead of 20% poloxamer. All formulations contained 10% CBZ. The characteristics of the suppositories differed depending on the formulation. The formula containing 20% poloxamer 407, 1% methylcellulose, and 0.5% carbopol showed reasonable gelation temperature, gel strength and bioadhesive force. The analysis of release mechanism showed that CBZ released from the suppositories by Fickian diffusion. In vivo evaluation of the same formulation showed higher peak plasma concentration of CBZ compared with the orally administered suspension containing the equivalent amount of drug. However, there was no statistical significant difference (p > 0.05) in extent of bioavailability between the liquid suppository and oral suspension as indicated by the values of AUC(0 - infinity), 17.9 and 18.8 micro g x h/ml, respectively. These results suggested that mucoadhesive in situ gelling liquid suppository could be an effective and convenient delivery system of carbamazepine.

Tea consumption, apoptosis, and colorectal adenomas.

Induction of apoptosis has been suggested as a mechanism for the anti-carcinogenic effect of tea constituents in animals and in vitro studies. We addressed this hypothesis in a human study. Study participants were consecutive patients who underwent colonoscopy at the UNC Hospitals (August 1998 to March 2000). Biopsies were taken from normal rectal mucosa. Apoptosis was scored by the terminal deoxyribonucleotide transferase-mediated digoxigenin dUTP nick end labeling (TUNEL) method and by standard morphological criteria. The analysis included 171 patients with adenomas (cases) and 323 adenoma-free controls. After adjusting for sex, age, race, and BMI, apoptotic score was inversely associated with adenoma: the odds ratios (ORs) for linear trend associated with tertiles were 0.3 (0.3-0.5) for morphologic score and 0.5 (0.4-0.6) for the TUNEL score, respectively. Tea consumption (2-3 and >3 versus <2 servings/day) showed a weak negative association with adenoma: the ORs were 0.7 (0.3-1.4) and 0.5 (0.2-1.1), respectively. Neither measurement of apoptotic score changed by the level of tea consumption (P value for Kruskal-Wallis test > or =0.5). We did not find statistical interaction between apoptotic score and tea consumption. Tea exposure is not associated with apoptosis in normal rectal tissue in vivo.

Rectal mucosal proliferation and risk of colorectal adenomas: results from a randomized controlled trial.

Although rectal mucosal labeling index is thought to be a useful surrogate biomarker for colorectal cancer, the ability of the index to predict future neoplasia is unclear. We obtained rectal mucosal biopsies from 333 participants of a randomized controlled chemoprevention trial of calcium supplementation to determine whether labeling index was correlated with concurrent or future colorectal neoplasms. Labeling index was measured using proliferating cell nuclear antigen immunohistochemistry. Adenomas were enumerated at the time of the biopsies (cross-sectional) and 3 years later (prospective). We used logistic regression to test for an association of adenoma occurrence with overall labeling index, the mean proliferative height, and labeling index in the upper 40% of colon crypts. In the cross-sectional analysis, we found indications that higher proliferation was associated with an increase in the prevalence of adenomas. The overall adjusted odds ratios (OR) (95% confidence interval) were 1.14 (0.90-1.45) per % crypt labeling index, OR 1.08 (0.99-1.19) for upper crypt proliferation, and OR 1.07 (1.03-1.12) for proliferative height. In contrast, individuals with higher labeling index at baseline were actually less likely to have adenomas in the prospective analyses: OR 0.80 (0.62-1.02) per % crypt labeling index, OR 0.86 (0.73-1.00) for upper crypt index, and OR 0.97 (0.93-1.01) for proliferative height. Proliferative index does not predict future colorectal neoplasia, although it may be weakly associated with the presence of current adenomas. These results have important implications for the design of future intervention studies. Although it may be attractive to include the measurement of intermediate markers in large controlled trials, until we have more confidence in their performance, we should rely on better proven and more reliable intermediates, such as adenomas.

Fecal diacylglycerol concentrations and calcium supplementation.

Growth factors are known to stimulate colonic proliferation via activation of protein kinase C by production of diacylglycerol (DAG) from membrane phosphatidyl inositol. Previous studies from our laboratories have shown that fecal bacteria can produce and metabolize DAG and that DAG can be absorbed by colonocytes, and thus might contribute to neoplasia. Calcium is a putative chemopreventive agent, and we have shown that calcium administration reduces fecal DAG concentrations, as well as rectal proliferation in patients after jejuno-ileal bypass surgery. The present study in normal volunteers eating self-selected diets demonstrates that fecal DAG concentrations are very constant with a coefficient of variation from 6.7 to 10.2%. Calcium administration showed a trend to reduce fecal DAG by 11% (P < 0.08). We conclude that fecal DAG levels can be determined in individuals on a self-selected diet from a single stool determination. If the trend to reduce fecal DAG by calcium is verified in more extensive studies, then the effects of calcium used in chemopreventive might, in part, reflect changes in the luminal lipid content.

Calcium and colorectal epithelial cell proliferation in sporadic adenoma patients: a randomized, double-blinded, placebo-controlled clinical trial.

BACKGROUND: The kinetics of colorectal epithelial cell proliferation is altered in patients at increased risk for colon cancer. Calcium administration ameliorates such proliferative changes in rodents. Findings in preliminary clinical trials have suggested similar effects in humans. PURPOSE: A randomized, double-blind, placebo-controlled, clinical trial was designed to determine whether calcium supplementation will reduce the colorectal epithelial cell proliferation rate and normalize the distribution of proliferating cells within colorectal crypts (i.e., shift the zone of proliferation from the entire crypt to the lower 60% of the crypt, which is thought to be the normal proliferative zone of the crypt) in patients with sporadic adenomas. METHODS: Sporadic adenoma patients (n = 193) were treated with placebo (n = 66), 1.0 g calcium (n = 64), or 2.0 g calcium (n = 63) daily for 6 months. Rectal mucosa biopsy specimens were obtained at base line and at 1-, 2-, and 6-month follow-up. Cell proliferation was measured by detection of S-phase-associated proliferating cell nuclear antigen by immunohistochemical methods. The cell proliferation rate, called labeling index (LI), was calculated as the proportion of labeled cells in the crypts. The deviation of the proliferative zone from the normal location in the lower 60% of the crypt was calculated as the proportion of labeled cells in the upper 40% of the crypt, called distributional index (phi h). The effects of calcium treatment on the LI and phi h were expressed as relative effects--(calcium follow-up/calcium base line)/(placebo follow-up/placebo base line). Calculations and inference testing of the relative effects were accomplished using a repeated-measures mixed model on log-transformed LI and phi h values. All statistical tests were two-sided. RESULTS: Scorable biopsy specimens were obtained on 170 patients at base line, 164 at 1 month, 161 at 2 months, and 163 at 6 months. The difference in the change in the LI between the combined calcium groups and the placebo group was insignificant, with a relative effect of calcium versus placebo of 0.97 (P = .87). However, for the phi h, the relative effect of calcium versus placebo was 0.50 (P = .05) in the combined calcium groups, 0.56 (P = .16) in the 1.0-g calcium group, and 0.44 (P = .05) in the 2.0-g calcium group. CONCLUSIONS: Calcium supplementation normalizes the distribution of proliferating cells without affecting the proliferation rate in the colorectal mucosa of sporadic adenoma patients. IMPLICATIONS: These results support further study of whether alterations in colon cell proliferative kinetics represent true intermediate steps in colon carcinogenesis that can be used to investigate the etiology and prevention of, and whether a higher calcium consumption can reduce the risk of, colon cancer.

Missing anti-proliferative effect of fish oil on rectal epithelium in healthy volunteers consuming a high-fat diet: potential role of the n-3:n-6 fatty acid ratio.

Several studies have indicated dietary fish oil (FO) as a protective agent in colon carcinogenesis. Rectal cell proliferation as an intermediate biomarker of cancer risk was shown to be reduced by dietary FO in patients with adenomatous polyps and healthy subjects consuming a low-fat diet. Because the synthesis of prostaglandins (PG) which seem to be involved in this process is dependent on the ratio of n-3:n-6 fatty acids in the diet, the present study was designed to investigate whether this FO effect is also detectable in volunteers eating a high-fat diet (50% of energy) with a low n-3:n-6 ratio of 0.25. Twelve healthy volunteers received in addition to a controlled basal diet either FO (4.4 g n-3 fatty acids/day) or corn oil supplements (double-blind, crossover) for two 4-week periods. No significant differences between the two study periods were found for rectal cell proliferation as assessed by bromodeoxyuridine immunohistochemistry and ornithine decarboxylase activity, as well as for mucosal PGE2 release and mucosal membrane fatty acid composition. The results emphasize the importance of dietary n-3:n-6 ratio in determining the effects of FO on rectal cell proliferation.

Effect of calcium supplementation on rectal epithelial hyperproliferation in intestinal bypass subjects.

BACKGROUND/AIMS: Fatty acids and bile acids are tumor promoters of experimental colon cancer in rats. Calcium can inhibit their effects. After intestinal bypass (IB), fecal bile acid and lipid levels increase markedly. In rats, IB increases colonic cell proliferation and carcinogen-induced colon tumor incidence. Whether fecal bile acids and lipids influence rectal epithelial proliferation in humans is uncertain. This study compared rectal epithelial proliferation in IB subjects and in controls matched for age, sex, and body mass index and investigated the effects of calcium carbonate supplementation (2400 or 3600 mg Ca2+/day for 12 weeks) on proliferation indices in IB subjects. METHODS: Epithelial proliferation was studied by in vitro incubation of rectal biopsy specimens with [3H] thymidine. Twenty-four-hour stool collections were assayed for bile acids, lipids, and calcium. RESULTS: Whole crypt labeling index (LI) and upper crypt LI were increased in IB subjects compared with controls (P < 0.005). Calcium reduced whole crypt LI by 38% (P < 0.001) and upper crypt LI by 56% (P < 0.05). Levels of fecal bile acids (4.5 mmol/day) and lipids (131.9 g/day) were markedly elevated in IB subjects (P < 0.005). CONCLUSIONS: IB induces rectal hyperproliferation and expansion of the proliferative zone in association with excessive output of fecal bile acids and lipids. Oral calcium reverses the proliferative changes.

Calcium reduces the increased fecal 1,2-sn-diacylglycerol content in intestinal bypass patients: a possible mechanism for altering colonic hyperproliferation.

Diacylglycerol (DAG) is a second messenger for protein kinase C, an enzyme with a key role in cellular signal transduction and growth control. In previous studies, it was demonstrated that DAG is produced by intestinal microflora. Bacterial DAG production is increased by bile acids and phospholipids, both of which may be precipitated by calcium. We have demonstrated that fecal total lipids, bile acids, and rectal epithelial proliferation are increased in intestinal bypass (IB) patients. Calcium was shown to alter fecal lipid composition and to reduce cell proliferation. In the present study, fecal DAG content and 14C-labeled DAG, 14C-phosphatidylcholine, and 14C-phosphatidylinositol metabolism were measured in 24-h stool collections in 15 stable IB patients before and after 3-month therapy with oral elemental calcium, 2.4 or 3.6 g/day. Fecal DAG concentration and output in IB patients were > 25- and > 200-fold greater than in normal controls. Oral calcium markedly reduced fecal DAG concentration and output and increased DAG, phosphatidylcholine, and phosphatidylinositol metabolism without enhancing DAG production. We conclude that fecal DAG content is markedly elevated post-IB and that calcium supplementation in these patients reduces fecal DAG and accelerates bacterial metabolism of DAG and its precursors. In separate studies, we have found that calcium supplementation also decreases rectal hyperproliferation in IB patients. Taken together, these findings suggest that a high luminal level of DAG enhances colonic cell proliferation and that calcium reduces cell proliferation in part by decreasing the level of DAG.

Reliability of rectal epithelial kinetic patterns as an intermediate biomarker of colon cancer.

The use of biomarkers to assess cancer risk is based on the model of cancer as a multistep process; such markers are assumed to reflect an early stage in this process. A valid biomarker of risk must therefore show differential expression in normal and high-risk subjects, as well as quantitative correlation with the stage of carcinogenesis. It should also be easy to detect in small tissue specimens and responsive to modulation by chemopreventive agents. Cell proliferation is one of the most widely investigated markers of cancer risk. Case-control studies have shown that epithelial cell proliferation parameters, assessed in rectal mucosal biopsies by means of in vitro autoradiographic or immunohistochemical techniques, can discriminate between populations with normal and high risks for colon cancer. However, we recently reviewed rectal biopsies from 152 subjects (43 controls, 84 with adenomas, 25 resected for colon cancer) processed for in vitro 3H-thymidine autoradiography, and attempted to correlate various proliferative parameters with clinical and pathological variables by means of multiple regression analysis. Elevations of total crypt labeling indices (LIs), particularly upper crypt LIs, were significantly associated with the presence of adenomatous polyps, although subsequent linear discriminant analysis revealed that the accuracy of LIs in discriminating between polyp patients and controls was actually quite low. However, we have also found that upper crypt LIs are reliable predictors of adenomatous polyp recurrence. Repeated evaluations of rectal proliferative indices over a 2-year post-polypectomy follow-up of 40 patients with colonic adenomas revealed substantial stability.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of fish oil on rectal cell proliferation, mucosal fatty acids, and prostaglandin E2 release in healthy subjects.

BACKGROUND: Experimental studies have indicated dietary fish oil as a protective agent in colon carcinogenesis. Prostaglandins have been suggested to be involved in this process. In the present study, the effects of fish oil on rectal cell proliferation (i.e., intermediate biomarker of cancer risk), mucosal membrane fatty acids, and prostaglandin E2 (PGE2) release were investigated in 12 healthy volunteers. METHODS: In addition to a controlled basal diet, the test subjects received either fish oil (4.4 g omega-3 fatty acids/day) or corn oil supplements for two 4-week periods in a double-blind, crossover trial. Rectal cell proliferation was determined by bromodeoxyuridine immunohistochemistry and ornithine decarboxylase activity. After 2-hour incubation with bromodeoxyuridine, PGE2 concentration in the incubation medium was measured by radioimmunoassay. Mucosal membrane fatty acids were analyzed by gas chromatography. RESULTS: Bromodeoxyuridine labeling index (9.2% vs. 10.9%; P < 0.05), ornithine decarboxylase activity (19.7 vs. 36.4 pmol.mg protein-1.h-1; P < 0.005), and PGE2 release from rectal biopsy specimens (435.5 vs. 671.5 pg/mg wet tissue; P < 0.05) were significantly lower during the fish oil than the corn oil period, whereas membrane fatty acids were not statistically different. CONCLUSIONS: The results support the hypothesis that dietary fish oil may protect against colon cancer.

Cell kinetics of the in vitro metaphase arrest technique and the clinical applications.

The in vitro metaphase arrest technique (crypt cell production rate-CPPR) has been used to measure human rectal mucosal proliferation. Study of preincubation times, dose response curves and lag phases suggest that a concentration of vincristine of 5 micrograms/ml and 16 hour preincubation with time point increments between 25 and 125 minutes give optimal conditions for measuring rectal mucosal proliferation. Twenty individuals had rectal CCPR repeated without intervention of any kind. Close correlation was found between the two values (r = 0.89 and P = 0.0001). The effect of polyethylene glycol bowel preparation was also studied in 35 subjects. There was good correlation (r = 0.66, P = 0.007). There was close correlation between rectal and caecal CCPR as measured in 20 patients who had colonoscopy (r = 0.72, P = 0.0003). The in vitro metaphase arrest technique is a useful parameter of rectal mucosal proliferation and may be used with confidence in a number of different clinical situations.

Modulation by dietary factors of BHA-induced alterations in cell kinetics of gastro-intestinal tract tissues in rats.

To determine the effects of dietary ethanol or fibre on 2(3)-tert-butyl-4-hydroxyanisole (BHA)-induced alterations in cell kinetics in gastro-intestinal tract tissues, groups of six male Wistar rats were fed diets containing 0% (control) or 1.5% BHA for 2 wk. One group fed 1.5% BHA and one pair-fed control group received 10% ethanol in the drinking-water; two similarly fed groups received drinking-water only. Another group fed 1.5% BHA and a pair-fed control group received a diet supplemented with 20% cellulose; two similar groups received no fibre supplementation. Cell kinetics in the forestomach, glandular stomach and oesophageal tissue were determined, after 14 days, by bivariate 5-bromo-deoxyuridine/DNA analysis using immunocytochemistry and flow cytometry. In the fibre experiment, colorectal tissue was also examined. In both experiments the labelling indices in all the gastro-intestinal tract tissues were significantly altered in the BHA-fed groups compared with the corresponding control groups. In the ethanol experiment no statistically significant difference in the labelling indices was observed in the forestomach or glandular stomach between the two control groups or between the two BHA-fed groups. However, intake of ethanol-supplemented drinking-water induced increases in oesophageal labelling indices in rats fed a BHA-free diet. Thus 14 days of simultaneous ethanol administration has no effect on BHA-induced alterations in cell kinetics in the oesophagus, glandular stomach or forestomach of rats. In the forestomach and colorectal tissue, a high-cellulose diet resulted in a significant decrease in the BHA-induced elevation of labelling indices. Thus dietary cellulose provides a partial protection against the proliferation-enhancing effects of BHA in the rat gastro-intestinal tract.

Oral calcium suppresses increased rectal epithelial proliferation of persons at risk of colorectal cancer.

Dietary calcium may inhibit colonic carcinogenesis promoted by high fat, phosphate, and low fibre diets. In persons at risk for colon cancer oral calcium supplements significantly suppress increased rectal epithelial proliferation. This was studied in a cohort of 35 volunteers: 26 first degree relatives of colorectal cancer patients and nine who had had colonic adenomas (mean age 51.6 years, 17 (49%) men, all negative for large bowel neoplasia). 1.25-1.5 g elemental calcium was given in divided daily doses for three months. Rectal pinch biopsies were taken without bowel preparation, before and mean 8.4 weeks during and 7.2 weeks after treatment and incubated with tritiated thymidine. The mean number of labelled cells, as a ratio of the total number of crypt cells (labelling index-LI), and their crypt position, were determined. The mean number of labelled cells decreased during treatment by 29%, especially in the basal three-fifths of crypts. There was also a significant 10% increase in mean number of crypt cells during treatment. [Mean LI decreased by 36% (p less than 0.001) during calcium treatment and almost returned to basal values after cessation.] If a raised LI is a marker of potential malignancy and a randomised clinical trial confirms that calcium suppresses it, dietary intervention studies in high risk persons are indicated.

Reproducibility studies and effects of bowel preparations on measurements of rectal epithelial proliferation.

Measurements of rectal epithelial proliferation (REP), using tritiated labelled thymidine, correlate with colonic epithelial proliferation, risk for cancer and response to therapies. There have been criticisms regarding its reproducibility and the possible deleterious effects of bowel preparations on this biomarker. We studied paired observations on 7 patients repeated without bowel preparation, 11 repeated after tap-water enema, and 8 repeated after PEG-electrolyte solution or extract of senna purgative and found no significant differences between paired observations. In addition, in a high-risk group for colorectal cancer, 31 persons received PEG or senna preparation and their REP was not significantly different from that of 23 examined without these preparations. Thus, REP is a reproducible biomarker and not affected by several commonly used bowel preparations.

Endorectal pull-through with conservation of the rectal mucosa: experimental study.

The present experimental work was designed to study an abdominoanal pull-through technique, with conservation of rectal mucosa. Continence was evaluated from clinical, radiologic, and histopathologic standpoints. The animals defecated normally. A good retention of barium was seen in the radiologic enema. On the reexploration of the animals, we found a distal dehiscence with elevation of the intussuscepted stump towards the rectum in all. A reepithelization process of serosa of the intussuscepted segment was noted.