The distribution of polypeptide YY-like immunoreactivity in rat tissues.

The distribution of peptide YY (PYY)-like immunoreactivity (IR) in rat tissues was determined by specific RIA after extraction with boiled 1 N acetic acid. The high concentration of PYY-IR was observed in the gastrointestinal tract, with concentrations gradually increasing from the duodenum to the end of colon. The concentration of PYY-IR in the colon was 298.7-449.5 pmol/g tissue (approximately 100-200 times more than that in the duodenum). Pituitary and pancreas contained measurable amounts of PYY-IR (6.8 and 6.3 pmol/g tissue). The concentration of PYY-IR in the mucosa was higher than that in the muscular layer in the small intestine, cecum, colon, and rectum. The ratio of the mucosal PYY-IR to the muscular PYY-IR was highest in the distal small intestine (4.7-6.8). Sephadex G-50 gel chromatography of the colon extracts revealed the one PYY-IR peak which corresponds to [125I]PYY. The gradual increase of PYY-IR from the duodenum to the end of the colon is different from the distribution of other known gut peptides.

Clostridium difficile--a spectrum of virulence and analysis of putative virulence determinants in the hamster model of antibiotic-associated colitis.

Each of nine different toxigenic strains of Clostridium difficile was administered orally to groups of hamsters pre-treated with clindamycin and housed individually in sterile isolator boxes. Faecal pellets and caecal contents from well, diarrhoeic, moribund and freshly dead animals were analysed for C. difficile and toxins A (enterotoxin) and B (cytotoxin), and tissue obtained when animals were killed was examined histologically. Not all strains were equally virulent in this model. Four strains of C. difficile killed all animals within 48 h and are designated as highly virulent for hamsters. These strains were clinical isolates from three cases of disease in man and one case in a hamster. Five strains caused death of some animals but only after 5 and upt to 13 days and are designated as less virulent for hamsters. These strains were isolated from asymptomatic infants (2) and household pets (2), and from the environment (1). The surviving test hamsters were killed after 14 days and, in most cases, were colonised by C. difficile, though levels of toxins A and B in caecal contents were low. None of the cultures used for challenge was capsulate or hydrophobic. There was no correlation between virulence and production of toxins A and B in vitro in tryptic-nitrate broth. With two strains examined, there was a correlation between virulence and toxin A (but not toxin B) production in caecal emulsions derived from clindamycin pre-treated hamsters. Caecal contents from the majority of moribund and freshly dead animals had quantities of toxin A sufficient to cause disease or death if given orogastrically. Toxin B was not produced in a fixed ratio with toxin A. The data support the view that high virulence of C. difficile is determined by efficient disease-inducing colonisation of the gut and the ability to generate, rapidly, high levels of toxin A in vivo.

Autoradiographic localisation of muscarinic receptors in guinea-pig intestine: distribution of high and low affinity agonist binding sites.

Muscarinic receptors mediate a variety of intestinal functions including smooth muscle contraction, ganglionic transmission and water and electrolyte secretion. In this study, we have used [3H]quinuclidinyl benzilate ([3H]QNB) in an in vitro autoradiographic method to map the distribution of muscarinic receptors in guinea-pig ileum, colon and caecum. In addition, the relative distribution of low and high affinity agonist binding sites was assessed by the addition of the muscarinic agonist, carbachol, to selectively inhibit the binding of [3H]QNB to the high affinity sites. Although quantitative differences existed, the overall distribution of muscarinic receptors was similar in the 3 regions of intestine examined. Autoradiograph grains were found distributed over the myenteric and sub-mucous plexuses, the longitudinal and circular muscle layers and in the case of the colon, the muscularis mucosa. The inclusion of carbachol demonstrated that a greater proportion of high affinity sites were associated with the musculature than with the enteric plexuses. These findings are discussed in relation to the role of muscarinic mechanisms in intestinal motility and secretion.

Adrenergic mechanism in cold stored taenia caecum after rewarming.

After cold storage of guinea-pig taenia strips for 4 days at 2 degrees C, structures with specific catecholamine fluorescence were not observed. Upon incubation in Krebs Ringer medium (37 degrees C) the fluorescence in the cold stored tissue reappeared and the density of fluorescence was comparable to that of fresh preparations. The specific fluorescence was affected following reserpine or 6-hydroxydopamine treatment; however, the rewarming process restored fluorescence only in the reserpine-treated tissue. The cold storage treatment (4 and 7 days) also decreased the tissue noradrenaline and dopamine contents and dopamine-beta-hydroxylase activity and inhibited the [3H-noradrenaline release from the tissue, all of which were not restored by the incubation procedure. Moreover, in these cold stored taenia the inhibitory effect to nicotine and perivascular nerve stimulation were not manifested. Therefore, the reappearance of specific fluorescence in the cold stored taenia strips after rewarming does not assure functional recovery of adrenergic nerve activity.

Intramural distribution of Met5-enkephalin-Arg6-Gly7-Leu8 in sphincter regions of the human gut.

The intramural distribution of Met5-enkephalin-Arg6-Gly7-Leu8 (MERGL) was studied in the oesophago-cardiac, pyloric, ileo-caecal and sigmoid-recto-anal regions of the human digestive tract. Serial samples encompassing each area were separated into mucosa, submucosa and muscularis externa and extracted for radioimmunoassay. Comparatively low levels of MERGL immunoreactivity were measured throughout the cardiac junction. Conversely, a remarkable peak of MERGL concentration was detected at the pyloric junction, in both submucosa and muscularis. A progressive decrease in tissue levels of the same peptide, most evident in the submucosa, was detected on the proximal side of the ileo-caecal region. In the distal sigmoid colon and rectum MERGL concentrations showed a rapid decline, down to very low levels in the anal canal. The results may suggest the involvement of an enkephalinergic mechanism in the control of the human pylorus.

Fecapentaenes and their precursors throughout the bowel--results of an autopsy study.

The fecapentaenes are potent mutagens found in the stool of some humans and pigs. These compounds are produced by Bacteroides species in the gut from an uncharacterized family of precursor compounds, and have been postulated to pose a risk of human colorectal cancer. To better understand fecapentaene production in vivo, and to determine if excreted levels measured in epidemiologic studies are representative of the entire colon, fecapentaenes were assayed from multiple sites in the bowel in an autopsy study of 16 humans and 2 pigs. An indirect measurement of fecapentaene precursors was also made. Colonic concentrations of fecapentaenes and precursors varied widely between individuals, but were consistent for each individual throughout the colon. In addition, the measurements of rectal contents, assumed to approximate values in excreted stool, were equivalent to measurements from the colon.

An improved procedure for bile acid extraction and purification and tissue distribution in the rat.

Two bile acid extraction procedures were compared using endogenously radiolabeled tissues and feces. The method of Setchell et al. (J. Lipid Res. 24, 1085-1100, 1983) resulted in essential complete extraction, whereas that of Manes and Schneider (J. Lipid Res. 6, 376-377, 1971) gave recoveries between 56-82%. The time requirement for the method of Setchell et al. could be drastically reduced with no loss in extraction efficiency. Using extracts from endogenously labeled material, a purification procedure using C18 solid-phase extraction cartridges was developed that recovers greater than 90% of bile acids. The distribution of bile acids within the intestinal tract and liver of the rat was determined.

The influence of putrefactive changes on the determination of Paraquat in autopsy materials.

This paper describes how the putrefactive changes in a cadaver will influence the determination of Paraquat in autopsy material. The carcasses of rats that had been given large doses of Paraquat and subsequently killed by cervical dislocation, were left at room temperature for up to seven days. Samples of stomach, caecum and liver were removed for the colorimetric determination of Paraquat with sodium dithionite following extraction on a Dowex 50W-4 column. Paraquat recovered from the stomach and caecum showed a decrease with time after death with the rate of decrease being greater in the caecum samples. However, the concentration of Paraquat in the liver increased for three days and then began to decrease gradually. The possible causes of these variations in Paraquat recovery are discussed. The findings appear to demonstrate the value of Paraquat determination even in samples from material that is in a state of advanced putrefaction.

Lectin and ultrastructural cytochemistry of glycoconjugates in the cecal epithelium of the chicken.

In the cecal epithelium of the chicken, glycoconjugates were studied by light microscopy with lectin-peroxidase and correlated procedures, and by electron microscopy with high iron diamine-thiocarbohydrazide-silver proteinate (HID-TCH-SP) and periodic acid (PA)-TCH-SP methods. Mucous granules of goblet cells and striated border of columnar cells at the basal cecum contained acidic and neutral glycoconjugates with sulfate ester, vicinal diol groupings and alpha-D-mannose, alpha-D-glucose, beta-D-galactose, N-acetyl-D-glucosamine, and sialic acid-galactose dimers. In addition, terminal galactose-(1-3)N-acetylgalactosamine disaccharides were detected. In the apical cecum, similar glycoconjugates involved in the mucous granules of goblet cells and the striated border of columnar cells were found to be smaller in amount. Terminal galactose-(1-3)N-acetylgalactosamine disaccharides together with glycogen particles were also visualized in columnar cells of the basal and apical cecum. The histophysiological significance of glycoconjugates involved in the chicken cecal epithelium was discussed.

A histochemical study of the mucins in the digestive tract of the chicken.

Little is known about the distribution of glycoproteins in the digestive tube of birds. In the present study, the localization and distribution of mucins in the digestive tract of the chicken are reported. Sialo- and sulpho-mucins were widely distributed throughout the chicken digestive tube. Some of the mucous cells of the proximal segment of the proventriculus presented neutral glycoproteins; in the medial segment, surface cells containing only sialo-mucins were observed. Surface cells of the gizzard contained both sialo- and sulpho-mucins while PAS-positive material was localized in the lumen of the glands. 2 types of mucous cells were observed in the small intestine; 1 type contained only sialo-mucins and the other contained both sialo- and sulpho-mucins. In the large intestine and caecum, both types of acid mucins were present in the mucous cells. In conclusion, the distribution of glycoproteins in the chicken reported in the present study show marked differences with that reported in other avian species.

Effect of diet on composition of cecal contents and on excretion and composition of soft and hard feces of rabbits.

A total of 260 New Zealand White growing rabbits were used to study the effect of diet on chemical composition of cecal contents and on production and composition of soft and hard feces. Eight diets varying in their acid detergent fiber (9.8% to 32.7%) and starch (13% to 30%) levels were evaluated. The diet affected (P less than .01) all the variables studied, except dry matter (DM) and molar proportions of volatile fatty acids on cecal contents. An increase of dietary crude fiber increased crude fiber level in cecal contents (from 11.58% to 26.53%). However, a relatively lower proportion of fibrous material was found in the cecal contents when rabbits were fed the more fibrous diets. This suggests that dietary fiber has a direct influence on the efficiency of particle separation in the digestive tract. Crude protein and volatile fatty acid concentrations of cecal contents decreased (from 30.14% to 19.65% and from 47.8 to 36.7 mmol/liter, respectively) when dietary crude fiber increased. This could be related to availability of energy to cecal microorganisms. Ammonia concentration of cecal contents was not affected by dietary crude fiber. Daily production of soft feces varied from 14.98 to 29.59 g DM/d, and the contribution of soft feces to total DM and to crude protein intake ranged from 10.6% to 15.0% and from 12.8% to 20.5%, respectively; these values were the smallest and the largest for the least and the most fibrous diets, respectively. From this study we conclude that dietary fiber has a major effect on the digestive processes in the rabbit and that dietary starch level has no influence on any of the variables studied.

Cecal short-chain fatty acids in experimental rabbit mucoid enteropathy.

Short-chain fatty acid concentrations were measured in the cecal contents of 9 healthy rabbits and 20 rabbits with experimentally induced mucoid enteropathy. In control rabbits, cecal concentration of acetate was the most abundant, followed by that of butyrate and propionate--a feature distinguishing rabbits from most other mammals. In mucoid enteropathy, cecal acetate and butyrate concentrations were lower, whereas propionate, isobutyrate, valerate, and isovalerate were increased. The results indicated that there were abnormal fermentation and cecal maldigestion in rabbits with mucoid enteropathy.

In vitro transport of L-alanine by equine cecal mucosa.

When sheets of mucosa from the cecum of clinically normal horses were incubated in vitro with radiolabeled L-alanine, they could accumulate this amino acid against an apparent concentration gradient after 60 to 150 minutes of incubation. The active transport system for L-alanine was on the serosal surface of the mucosal sheet only. L-Alanine accumulation at 60 minutes was partly inhibited by 20 mM glycine (P less than 0.01), 0.5 mM ouabain (P less than 0.05), and Na deprivation (P less than 0.02). Anoxia for 60 minutes increased L-alanine accumulation, but had adverse effects on cell structure and intracellular cation distributions. Transmucosal fluxes induced a small, but significant (P less than 0.05), net secretion of L-alanine, and the mean (+/- SEM) transmucosal potential difference was 7.3 +/- 0.7 mV over the period of flux measurement. It was concluded that L-alanine was accumulated by the serosal surface of the cecal mucosa, possibly to provide substrate for tissue metabolism. There was no evidence that the cecal mucosa could actively transport this amino acid from the luminal bathing medium.

Inorganic ions in the intestinal and caecal contents of germ-free and conventional chickens.

In 4-week-old chicks that had been maintained on 3 different diets, caecal weights were lower in germ-free than in conventional birds eating practical but not semipurified diets. There were no consistent differences in total sodium, potassium and chloride ions in the contents of the small intestine. In germ-free chicks the caecal wall muscle appeared lacking in tone and there was a lower concentration of chloride ions in the contents, but there was no caecal enlargement comparable to that in germ-free rodents.

Association of germfree mice with intestinal microfloras obtained from "normal" mice.

A cultured microflora obtained from the caecum of a "normal" mouse was given to 4 groups of germfree mice and was supplied 1x, 2x, 3x and 4x respectively at 5-day intervals. Another group received a 10(-7) dilution of the caecal flora while a group associated with an 'SPF' flora served as control. The difference (measured by 8 parameters) between mice supplied with the cultured flora or with a 10(-7) dilution, both given once only, was small. Supplying the flora 3x resulted in more 'normal' mice compared with mice which received the flora once or twice. The caeca of specified-pathogen-free mice contained more bacteria per gram (microscopic bacterial count), less aerobic and anaerobic bacteria per gram (viable counts), while the yield as percentage of the microscopic bacterial count was lower as compared with the group to which a cultured flora was supplied 4 times.

The 'normalization' of germ-free rabbits with host-specific caecal microflora.

Hysterectomy-derived germ-free rabbits were given colonization-resistant caecal flora (CRF) from mice, or microflora obtained from the caecum of an antibiotic-decontaminated conventional rabbit and compared with rabbits conventionally raised with the doe. Bodyweight and the following intestinal parameters were determined for the 3 groups: colonization resistance to E. coli, relative caecal weight, villus:crypt ratio (ileum), beta-aspartylglycine (faeces), volatile fatty acids (caecum), and bile acids (faeces). Germ-free rabbits given mouse CRF-flora showed values quite different from control animals for most parameters, indicating unsuitability of mouse CRF flora to 'normalize' rabbits. In germ-free rabbits given modified (antibiotic-treated) rabbit flora, values for most parameters were intermediate between those found for the other 2 groups. This species-specific caecal flora should be improved to provide full 'normalization' of germ-free rabbits.

Measurement of uric acid levels in chicken cecal contents.

Uric acid levels in the cecal contents of White Leghorn males aged 6, 10, and 24 weeks of age were constant at approximately 2 mg/100 ml. Fecal samples obtained from these birds contained, respectively, 99, 107, and 156 mg/100 ml uric acid. The addition of growth promoting level of antibiotics or other feed additive to the ration of 10-week-old White Leghorn males had no effect upon cecal uric acid levels.

Changes in cecal composition with Eimeria tenella infection.

In each of three trials, the wet and dry weights of Eimeria tenella infected ceca were significantly increased compared to the control. The percentage of moisture and lipid in the cecal tissue remained unchanged or slightly increased. These effects were observed for all parasite strains examined and were detectable as early as day 4 postinoculation. Analysis of cecal protein and DNA suggested a uniform increase in cecal tissue rather than the production of a specific protein or component in response to the infection. Histological measurements of infected ceca, compared with the control, showed a twofold increase in both mucosal thickness and muscular thickness.

[Effects of ceftizoxime suppository rectal dosing on cecal microflora in mice].

The effect of ceftizoxime suppository (CZX-S), a new rectal preparation of ceftizoxime (CZX), against cecal microflora of mice following consecutive rectal administration was compared with that after subcutaneous administration of CZX. The numbers of aerobic and anaerobic bacteria except Enterobacteriaceae of cecal microflora were not markedly changed by the rectal administration of CZX-S at a dose of 25 mg/kg 3 times daily for 10 days. Although the number of Enterobacteriaceae was decreased, recovery was rapidly observed after completion of the administration period. In the case of subcutaneous administration, a decrease in Enterobacteriaceae was also observed, but this was no more remarkable than that occurring with rectal administration. Moreover, effects on the state of feces, i.e., diarrhea, were not observed in any of the mice. The peak level of CZX in the cecum contents when administered rectally at a dose of 25 mg/kg was 13.8 micrograms/g at 4 hours, while it was less than the determination limit (2.0 micrograms/g) when administered subcutaneously at the same dose.