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Previous studies have suggested that intestinal microbiota modulates colonic epithelium renewal. The objective of our work was to study the effects of microbiota on colonic epithelium structure and cell cycle-related proteins by using gnotobiotic rats. Colonic crypts and amount of cell cycle-related proteins were compared between germ-free (GF), conventional (CV), and conventionalized rats by histochemistry and Western blot. Ki67 and proliferating cell nuclear antigen (PCNA) were used as surrogates for proliferative cells; [p21.sup.cip1] and [p27.sup.kip1] were markers of cell cycle arrest; anti- and proapoptotic proteins, Bcl2 and Bax, respectively, were also studied. We observed 40% increase of the crypt proliferative area 2 days after inoculation of GF rats with a complex microbiota. This recruitment of proliferative cells may account for the 30% increase of crypt depth observed between CV and GF rats. The hyperproliferative boost induced by microbiota was compensated by a fourfold increase of [p21.sup.cip1] and [p27.sup.kipl] involved in cell cycle arrest and a 30% drop of antiapoptotic Bcl2 protein while Bax was unchanged. Inductions of [p21.sup.cipl], [p27.sup.kipl], and PCNA protein were not paralleled by an increase of the corresponding mRNA. We also showed that [p21.sup.cipl] induction by microbiota was partially restored by Bacteroides thetaiotaomicron, Ruminococcus gnavus, and Clostridium paraputrificum. Colonization of the colon by a complex microbiota increases the crypt depth of colon epithelium. This event takes place in conjunction with a multistep process: a hyperproliferative boost accompanied by compensatory events as induction of [p21.sup.cipl] and [p27.sup.kipl] and decrease of Bcl2. intestine; germ-free; PCNA; Bcl2; [p21.sup.cipl] ; [p27.sup.kipl] doi: 10.1152/ajpgi.00384.2009.

In short bowel syndrome (SBS), although a remaining colon improves patient outcome, there is no direct evidence of a mucosal colonic adaptation in humans. This prospective study evaluates morphology, proliferation status, and transporter expression level in the epithelium of the remaining colon of adult patients compared with controls. The targeted transporters were [Na.sup.+]/[H.sup.+] exchangers (NHE2 and 3) and oligopeptide transporter (PepT1). Twelve adult patients with a jejuno-colonic anastomosis were studied at least 2 yr after the last surgery and compared with 11 healthy controls. The depth of crypts and number of epithelial cells per crypt were quantified. The proliferating and apoptotic cell contents were evaluated by revealing Ki67, PCNA, and caspase-3. NHE2, NHE3, PepT1 mRNAs, and PepT1 protein were quantified by quantitative RT-PCR and Western blot, respectively. In patients with SBS compared with controls, 1) hyperphagia and severe malabsorption were documented, 2) crypt depth and number of cells per crypt were 35% and 22% higher, respectively (P < 0.005), whereas the proliferation and apoptotic levels per crypt were unchanged, and 3) NHE2 mRNA was unmodified; NHE3 mRNA was downregulated near the anastomosis and unmodified distally, and PepT1 mRNA and protein were unmodified. We concluded that, in hyperphagic patients with SBS with severe malabsorption, adaptive colonic changes include an increased absorptive surface with an unchanged proliferative/apoptotic ratio and well-preserved absorptive NHE2, NHE3, and PepT1 transporters. This is the first study showing a controlled nonpharmacological hyperplasia in the colon of patients with SBS. nutrition; colonic hyperplasia; proliferation markers; Ki67; PCNA; caspase-3; [Na.sup.+]/[H.sup.+] exchanger 3; [Na.sup.+]/[H.sup.+] exchanger 2; PepT1; hyperphagia

Of the oil-soluble organosulfur compounds derived from garlic, diallyl disulfide (DADS) is one of the most abundant. We examined the effect of DADS on gene expression in rat liver. By suppressive subtractive hybridization, we identified the heavy (H)-ferritin gene as a DADS-stimulated gene in the rat liver epithelial (REL) cells. DADS stimulation of H- and L (light)-ferritin mRNA was analyzed in REL cells and in rat liver. Incubation of the REL cells in 10 [micro]mol/L DADS for 4 h increased H-ferritin 1.9 [+ or-] 0.2-fold, n = 3) and light(L)-ferritin mRNA 1.5 [+ or -] 0.2-fold, n = 3). Stimulation did not occur in the presence of an inhibitor of transcription, actinomycin D. Stimulation of ferritin at the RNA and protein levels was also found in rats administered a DADS-enriched oil solution intragastrically. There was a 3 [+ or -] 1.1-fold increase in H- and 3 [+ or -] 0.14-fold increase for L-ferritin mRNA 24 h after the end of the infusion in the presence of DADS, (n = 3). The expression of the transferrin receptor, an iron transporter, was also enhanced by DADS in rat liver. In conclusion, our data suggest that DADS could modify iron homeostasis through the modulation of ferritin and transferrin receptor gene expression. J. Nutr. 132: 3638-3641, 2002. KEY WORDS: * organosulfurcompounds * garlic iron metabolism * subtractivehybridization

The characteristics of intestinal glucose metabolism were analyzed in the isolated enterocytes of newborn pigs to characterize the effects of metabolic changes in intestinal glucose utilization. Analysis of glucose kinetics in the isolated enterocytes of newborn pigs indicated the presence of age-related changes in glucose metabolism. Furthermore, the proximal-to-distal gradient of glucose utilization developed along the small intestines of the suckling pig.

The capacities of viable colonic epithelial cells to metabolize glucose, glutamine and n-butyrate were studied in 30-kg pigs adapted to a high fiber (12% sugar beet fiber) or a low fiber diet. Glucose and glutamine were extensively utilized but predominantly not oxidized, whereas n-butyrate oxidation accounted for 45% of n-butyrate metabolism and was not greatly affected by the presence of glucose or glutamine. With both diets, glycolysis was the major pathway accounting for glucose disappearance. There was a sparing effect of n-butyrate on both glycolysis and glucose oxidation. Moreover, the glycolytic capacity was 25% lower in pigs fed the high fiber diet. Data suggest that 6-phosphofructo-1-kinase could be the regulatory step in glycolysis. Nevertheless, its maximum activity was not affected by the diet or by the presence of n-butyrate. Glutamine metabolism was slightly affected by fiber in the diet and by the presence of n-butyrate. In addition to CO2, butyrate was converted into ketone bodies. Glucose and glutamine did not substantially alter n-butyrate metabolism. We conclude that some metabolic features of pig colonocytes, such as the capacity to oxidize n-butyrate, resemble those of rat and human colonocytes. Moreover, some characteristics, such as the glycolytic capacity, can be modulated by the level of fiber in the diet.

During the perinatal period the newborn must adapt to a different environment from that of the womb. After birth, maternal supplies of nutrient ceases requiring changes in glucose and fatty acid metabolism stimulated by alterations in hormone secretion. The suckling-weaning transition also changes nutritional patterns in the neonate resulting in further metabolic adaptations of glucose and fat metabolism.

The changes in long-chain fatty acid oxidation during the first 24 h after birth were studied in isolated rabbit hepatocytes and liver mitochondria. The eightfold increase in this oxidation which occurs in hepatocytes between birth and 24 h was not triggered by a concomitant decrease in long-chain fatty acid esterification. Indeed, in isolated hepatocytes from 24-h-old rabbits, the 75% inhibition of the oxidation by 2-tetradecylglycidic acid, resulted in a total redirection of oleate metabolized towards triacylglycerol synthesis. Polarographic measurements of mitochondrial respiration showed that oxidative phosphorylation and respiratory chain capacity were fully functional at birth. By contrast, in liver mitochondria isolated from newborn rabbits, the rate of oxygen consumption from palmitoyl-L-carnitine was 60% higher than from palmitoyl-CoA. Similarly palmitoyl-CoA oxidation was increased 1.5-fold in isolated mitochondria from 24-h-old rabbits. These results were in agreement with the twofold increase in the activity of hepatic camitine palmitoyltransferase I between birth and 24 h. However it is unlikely that the twofold increase in this enzyme activity totally explained the eightfold increase in long-chain fatty acid oxidation in isolated newborn rabbit hepatocytes. It was shown that the rate of the oxidation in isolated hepatocytes was inversely related to the rate of lipogenesis. Nevertheless, malonyl-CoA concentration per se is probably not the factor involved in the regulation of the oxidation between birth and 24 h, since a 90% decrease in hepatic malonyl-CoA concentration was not associated with a stimulation of long-chain fatty acid oxidation. The more likely mechanism was the 30-fold decrease in the sensitivity of carnitine palmitoyltransferase I to malonyl-CoA inhibition. [ABSTRACT FROM AUTHOR]