Small Intestine Of Man Research Articles

The movements of the adult Ascaris lumbricoides.

Abstract Deductions made from Makidono's (1956) observations of the movements of ascarids in the small intestine of man and from findings at surgical operations and post-mortem examinations of the positions of ascarids causing clinical disturbances have been used to build a concept of the behaviour of ascarids under normal and abnormal conditions.

What is fibre? Current controversies

While there has been much controversy over the definition of dietary fibre it has become clear that the basic definition accepted by scientists throughout the world was put forth in 1976 by Trowell and associates and is that dietary fibre is composed of the remnants of plant cells resistant to hydrolysis by human alimentary enzymes and that it includes all indigestible polysaccharides (celluloses, hemicelluloses, oligosaccharides, pectins, gums, waxes) and lignin [1]. This definition served the scientific community well until it was discovered that there were classes of compounds that did not precipitate in 78% ethanol (the classical Association of Official Analytical Chemists International [AOAC] method for dietary fibre analysis) and which possessed many of the characteristics we normally associate with dietary fibre and yet were resistant to hydrolysis by the enzymes in the small intestine of man. At this time a committee of scientists from the American Association of Cereal Chemists (AACC) are holding meetings, and has invited the scientific community at large to participate in this effort to determine if the definition of dietary fibre shall remain as originally proposed, or due to the accumulation of scientific data, be changed or altered in any way to accommodate these compounds.

Recovery of inulin from Jerusalem artichoke (Helianthus tuberosus L.) in the small intestine of man

The recovery of inulin, a naturally occurring beta (2-->1)-fructan isolated from Jerusalem artichoke (Helianthus tuberosus L.), in the small intestine of man was studied in ileostomy subjects. The ileostomists were given a low-dietary-fibre diet based on white wheat bread and virtually free of inulin, and the same diet with the addition of 10 g and 30 g inulin product respectively, and the recovery and mean transit time (MTT) of inulin were estimated by tracking inulin in ileal effluent. The recovery of inulin was approximately 87% at both ingestion levels. MTT was 4.9 (SE 0.6) h at an intake of 10 g inulin product decreasing to 3.4 (SE 0.3) h at an intake of 30 g inulin product. A significant change in the fructose:glucose ratio of inulin from ingestion (4.1) to recovery in ileal effluent (4.5-4.7) and a lower recovery of the glucose residue than of the fructose residue of inulin indicate that the low-molecular-weight inulins are more sensitive to hydrolysis than the high-molecular-weight fragments. The loss of inulin during passage through the small intestine is presumably due to hydrolysis by either acids or enzymes and to microbial degradation by the microflora permanently colonizing the distal small intestine. The concentrations of lactic acid (LA) and short-chain fatty acids (SCFA) in frequently collected ileal effluents on the control day were approximately 6 nmol/l and approximately 55 mmol/l respectively. During periods with inulin ingestion the concentration of LA increased to 18-26 mmol/l (P < 0.052), while the concentration of SCFA ran converse and decreased to 18-32 mmol/l (P < 0.023). The osmotic loads (68 and 204 mosmol/l) associated with the ingestion of inulin product caused minor malabsorption of low-molecular-weight sugars.

Age-induced nerve cell loss in the myenteric plexus of the small intestine in man.

We examined the number of nerve cells of the myenteric plexus and the thickness of the smooth muscle in the small intestine in autopsy material of 6 young and 6 old persons. Neurons in the myenteric plexus have been visualised by a nonhistochemical method (Giemsa) in laminar preparations of the muscularis externa. Significant reductions of at least 34% in the number of neurons in the ganglia of the myenteric plexus of the old subjects were recorded in all regions of the small intestine, especially in the duodenum where the number of neurons decreased by over 38%. However, there was no significant correlation between nerve cell count and thickness of intestinal smooth muscle since no difference was found in thickness of intestinal smooth muscle between young and old subjects. The decrease in the neuron density with age could affect the potential of the enteric nervous system to influence control over several small intestinal functional parameters.

Calcitonin Gene-Related Peptide (CGRP) modulates cholinergic neurotransmission in the small intestine of man, pig and guinea-pig via presynaptic CGRP receptors

The effect of calcitonin gene-related peptide (CGRP) on the cholinergically mediated twitch contraction in longitudinal muscle strips of the small intestine (duodenum, jejunum, ileum) of guinea-pig, pig and man was investigated. Independently of the anatomical region, CGRP inhibited the twitch response in the different specimens of all three species by about 40% with similar IC 50 values (1.5–2.4 nmol/l). Only in the guinea-pig small intestine CGRP induced a contraction of the smooth muscle which was sensitive to scopolamine and tetrodotoxin. The electrically evoked [ 3H]acetylcholine release from jejunal longitudinal muscle strips with myenteric plexus attached of the guinea-pig, which were incubated with [ 3H]choline, was concentration-dependently inhibited by CGRP. A direct relaxant effect of CGRP on smooth muscle tone of carbachol precontracted preparations was only observed in specimens of the guinea-pig. In conclusion, presynaptic inhibitory CGRP receptors on cholinergic neurones modulate the release of acetylcholine in different parts of the small intestine.

Variations in the occurrence of silver‐staining nucleolar organizer regions (AgNORs) in non‐proliferating and proliferating tissues

Previous studies on the subject of silver-staining nucleolar organizer regions (AgNORs) as indicators of precise proliferative status of tissues have sometimes resulted in ambiguity. The studies, however, have most frequently addressed themselves to the prognosis of neoplasias, with the aim of using AgNORs principally to distinguish between benign and malignant tumours. This investigation was to determine a base-line relationship of AgNOR clusters to proliferation and thus concentrated on normally proliferative tissues and conditionally renewing tissues after appropriate stimulation. Two murine transplantable tumours were also examined as examples of frank malignancy. As an example of the former, variations in AgNOR clusters were noted in the small intestine of man, mouse, and rat. The conditionally renewing systems of liver, prostate, and salivary glands were stimulated into proliferation by two-thirds partial hepatectomy, castration followed by treatment with testosterone, and isoproterenol treatment, respectively, in rat models; the murine sarcoma SaF and carcinoma CaNT provided relatively simple malignant tumours for AgNOR investigation. Proliferation was monitored by noting labelling indices after injection with bromodeoxyuridine (BrdUrd) in vivo followed by immunocytochemical visualization of S-phase cells. In all tissues, an increase in the size of AgNOR clusters rather than their number correlated positively with elevated labelling, particularly with the emergence of silver-staining regions of 2-3 microns visible diameter. Thus, increased AgNOR cluster size (diameter) as representative of AgNOR cluster/nucleolus volume was found to be dependent on proliferative activity in a range of normal and neoplastic tissues.

Induction of phase 3 of the migrating motor complex in human small intestine by trimebutine.

The effects of trimebutine, a drug used in the treatment of various gastrointestinal motility disorders, have been investigated fed and fasted healthy subjects. Duodenojejunal motility was recorded manometrically with a 4-lumen probe. Trimebutine 50 or 100 mg was injected i.v. 3 or 25 min after observing a spontaneous Phase 3 complex in the fasted state. Other experiments were done in the postprandial state and after intravenous naloxone 0.8 mg. In the fasted state, trimebutine 100 mg, injected 25 min after a spontaneous Phase 3 complex consistently induced a premature Phase 3 complex. The mean duration of the migrating motor complex cycle decreased from 86.4 +/- 10.8 min to 32.5 +/- 1.0 min. Trimebutine 50 mg injected 3 and 25 min after a spontaneous Phase 3 complex did not significantly modify the periodicity of the migrating motor complex. Trimebutine 100 mg initiated Phase 3-like activity in the post-prandial state. Previous intravenous administration of naloxone 0.8 mg (Narcan) suppressed the stimulatory action of TMB. Thus, trimebutine is able to modify the motility pattern in the small intestine of man, possibly by acting at opioid receptors.

Digestion of polysaccharides of potato in the small intestine of man

Digestion and absorption from the small intestine of starch and nonstarch polysaccharides (NSP) (dietary fiber) from potato cooked and treated in various ways have been studied in ileostomy subjects. Test meals (300 g) of potato were fed following 24 h on a plant polysaccharide-free diet. Regardless of the treatment the potato had received, greater than 90% of NSP was recovered in ileostomy effluent. Starch from freshly cooked potato was well digested, only 3% being recovered; however, 12% from cooked and cooled potato escaped digestion in the small intestine. Digestibility of starch made resistant to alpha-amylase by cooling improved on reheating. Overall, 9, 18, and 14% of total carbohydrate fed was recovered from freshly cooked, cooled, and reheated potato, respectively. Digestibility of cooled potato was identical when eaten as large lumps or as finely sieved potato. In vitro studies with pancreatin also demonstrated incomplete digestion of cooled potato.

Breakdown of resistant and readily digestible starch by human gut bacteria

AbstractCooking and processing of starch‐containing foodstuffs results in a portion of the starch becoming resistant to hydrolytic enzymes secreted in the small intestine of man. In order to determine whether this resistant starch (RS) was degraded in the colon, samples of RS and readily digestible starch (RDS) for comparisons were incubated with (a) cell‐free supernatants from faecal suspensions and (b) washed faecal bacterial cell suspensions. The data obtained showed that, whereas pancreatic amylase and faecal supernatants hydrolysed RDS, with the production of oligosaccharides, RS totally resisted breakdown. In contrast, both RS and RDS were completely degraded by the washed bacterial cells with the generation of volatile fatty acids (VFA) and organic acids. Hydrolysis and fermentation of RDS was extremely rapid and, as a consequence, oligosaccharides and lactate initially accumulated in the culture medium. RS was broken down more slowly, howevér, and oligosaccharides and lactate never accumulated. The rate of polysaccharide hydrolysis had a significant effect on the quantities of VFA produced, in that 54% of carbohydrate was fermented to VFA in cultures incubated with RDS as sole carbon source as compared to only 30% in cultures incubated with RS. However no qualitative difference was observed in the VFA produced by fermentation of RDS or RS.

Digestion of the polysaccharides of some cereal foods in the human small intestine

The digestion and absorption of dietary starch and nonstarch polysaccharides (NSP) in the small intestine of man from oats, cornflakes, and white bread has been determined by feeding seven ileostomists test meals containing these foods and estimating carbohydrate recovery in the effluent. NSP, the main constituent of dietary fiber, was almost completely recovered from all three test meals, including the water soluble beta-glucan which is the main NSP in oats. Less than 0.6% of the starch in oats was recovered as starch with a further 1.2% as dextrins and maltose. 4% of cornflake starch however was recovered, of which the main part was resistant to alpha-amylase digestion in vitro unless specially dispersed. Similarly with white bread 2.5% of ingested starch reached the terminal ileum of which the greater part was starch resistant to alpha-amylase in vitro. Overall 5.8% of the carbohydrate in white bread, 5.3% in cornflakes, and 11.7% in oats was recovered. This study supports the view that human digestive enzymes do not break down dietary NSP. It also identifies a fraction of starch, RS, present in processed food which resists breakdown by alpha-amylase both in vitro and in the small intestine of man.

A Simple and Economical Modification of the Masson-Fontana Method for Staining Melanin Granules and Enterochromaffin Cells

Enterochromaffin cells from the small intestine of man, guinea pig, dog, chicken, rabbit, cat and rat were stained using the Masson-Fontana ammoniacal silver method with varying dilutions of silver nitrate solution (0.25 to 5 g per 100 ml of distilled water) and incubation temperatures (60 C and 75 C). The 0.5% solution of silver nitrate gave an argentaffin pattern similar to that of the 5% solution and had two major advantages: economically, since much less silver nitrate is used, and methodologically, since low background resulted with tissue of those species (rat, cat and rabbit) that required unusually long incubation. The staining of melanocytes was similar for all dilutions at the usual staining time (15-30 min).

Morphology and chronology of ischemic mucosal changes in the small intestine. A light and electron microscopic investigation.

The morphology and chronology of an absolute ischemia was investigated on the small intestine of man and rat. It could be shown that the morphogenesis of ischemic damage to the intestinal mucosa in man does not differ from that in the rat. However, there are crucial and in therapeutic terms significant differences in the time course of the ischemic damage to the intestinal mucosa. Whereas in the small intestine of the rat, the first appreciable alterations - detachment and disruption of the lining epithelium at the villous tip - are already to be observed after absolute ischemia lasting 15 min, in the human small intestine the same lesions only occur after 4 h. A comparable complete necrosis of the small intestinal mucosa was detected in the rat after 7-h ischemia, and in man after 44-h ischemia.

Psychological stress and the passage of a standard meal through the stomach and small intestine in man.

Gastric emptying half-time and mouth to caecum transit time of a solid meal were measured in eight normal volunteers, once during a period of psychological stress and again during a period of relative calm. No consistent or significant effect on gastric emptying was observed, but mouth to caecum transit times were faster in all subjects and this difference was highly significant (p<0.01).

Psychological Stress and the Transit of a Standard, Solid Meal through the Stomach and Small Intestine in Man

Psychological Stress and the Transit of a Standard, Solid Meal through the Stomach and Small Intestine in Man

Villous damage induced by suction biopsy and by acute ethanol intake in normal human small intestine.

Previous studies by us indicated that ethanol in concentrations of 2.0-4.8% produced subepithelial blebs in the jejunum of the hamster. In the rat, due to rupture of the blebs, there was denudation of the villus tip epithelium. There are nos similar data on humans. Ethanol, in quantities equivalent to 4.8-6.4 ounces of 80 proof whiskey (diluted to 20% w/v), was infused into stomachs of 20 normal human volunteers. Subjects were divided into groups (Gr) according to the amount or type of alcohol given, and site of biopsies (SB). Gr 1:60 g ethanol, SB = jejunum. Gr 2:45 g ethanol, SB = jejunum. Gr 3:45 g ethanol, SB = duodenum. Gr 4:45 g ethanol as 4.8 oz 80 proof whiskey, SB = duodenum. To compare the morphology in the absence and presence of ethanol, biopsies were obtained from each volunteer before ethanol administration (control period), immediately after peak ethanol concentration in the duodenum or jejunum (ethanol period), and when intraluminal ethanol concentration fell towards zero (recovery period). The mean peak intraluminal ethanol concentrations in the four groups varied between 5.69% and 9.37% (w/v). Ethanol-induced damage was evaluated using strict preset criteria. Coded slides were evaluated by two observers. Suction biopsy damaged 18% of the villi even in biopsies obtained during the control period. Ethanol produced a statistically significant increase in the number of damaged villi (mean of all groups 45%, range: 32% in Gr 2 to 62% in Gr 3). During the recovery period the number of damaged villi fell to that seen in control period biopsies. Ethanol, in quantities equivalent to those ingested during moderate drinking, may produce transient damage to the upper small intestine of man. Conversely, ethanol may simply increase the susceptibility of the mucosa to the unavoidable trauma of suction biopsy. However, the histological and ultrastructural changes were similar to those induced by ethanol in small laboratory animals.

Quantification of α-glucosidases along the villus of the small intestine in man

A method is introduced which enables the two-dimensional detection and analysis of absorbancy-values from continuous dye-deposites with rather low data storage capacity. Applied to histochemical reactions this method is used for kinetic analysis of enzymes along the intestinal villus. Its main part consists of two programs for two dimensional scanning, i.e. along the villus and at right angle from the lumen across the brush-border membrane to the apical cytoplasma. Two further programs serve as prerequisites: the automatical detection of mean values and the description of absorbancy spectra in the tissue section. The measurements are carried out with a MPVII Leitz in connection with a Hewlett Packard 9815 A calculator. The study of alpha-glucosidases of the human small intestine is taken to demonstrate the value of the method. It is shown that a similar Vmax-gradient along the villus can be demonstrated as by microchemical methods. Thus this method enables the description of the kinetic properties of a distinct enzymatic activity in preserved tissue sections on the cellular level and the possible alterations of Vmax and Km in context to the morphological pattern.

Immunochemical studies on cholecystokinin. II. Distribution and molecular heterogeneity in the central nervous system and small intestine of man and hog.

Immunochemical studies on cholecystokinin. II. Distribution and molecular heterogeneity in the central nervous system and small intestine of man and hog.

Production of adenocarcinomas of the small intestines of Wistar rats fed panfuran-S containing 3-di(hydroxymethyl)amino-6-(5-nitro-2-furylethenyl)-1,2,4-triazine.

Panfuran-S in the diet produced a high incidence of invasive and metastatic adenocarcinomas of the duodenum and the jejunum in outbred Wistar rats. Depressed growth and incidence of cancer production were dose-dependent. Adenocarcinomas of the duodenum were present in 2 of 18 (11%) rats that received 1,750 ppm 3-di(hydroxymethyl)amino-6-(5-nitro-2-furylethenyl)-1,2,4-triazine (DHNT) in the diet and in 11 of 19 (58%) rats that received 3,500 ppm DHNT. Adenocarcinomas of the jejunum were present in 10 of 18 (56%) and 16 of 19 (84%) rats that received 1,750 and 3,500 ppm DHNT, respectively, for 35-37 weeks. The only other tumors observed were squamous cell papillomas of the forestomach. Histologically, most of the adenocarcinomas appeared tubular or papillary and were similar to adenocarcinomas in the small intestine of man and also to human intestinal-type adenocarcinoma of the stomach. This system provided a useful experimental model for the study of the pathogenesis of carcinoma of the small intestine.

Evidence for the existence of a countercurrent exchanger in the small intestine in man

The vasculature in the human villus forms vascular loops by the supplying arterial vessel and the draining capillaries and/or veins. This study reports two experimental observations that strongly suggest that these vascular loops function as countercurrent exchangers. (1) The elimination of intraarterially injected 85Kr from the human small bowel exhibits an initial very rapid component of the type earlier reported in the feline gut. This component in all probability reflects the extravascular “shunting” in the exchanger of the injected radioactive tracer. (2) When exposing the intestinal mucosa to an isotonic electrolyte solution containing glucose, an osmolality gradient from the tip to the base of the human villi was demonstrated, the tips having an osmolality of around 700 milliosmoles per kg H2O. This hyperosmolality is created by the exchanger acting as a countercurrent multiplier.

Postprandial serum bile acids in healthy man. Evidence for differences in absorptive pattern between individual bile acids.

The serum concentrations of cholic acid (C), chenodeoxycholic acid (CD), and deoxycholic acid (D) before and after a standardised meal were determined in five healthy female subjects using a highly specific and accurate gas chromatographic-mass spectrometric technique. The C level rose significantly 60 minutes after the meal, reached a peak after 90 minutes, and had returned to the original level after 150 minutes. In contrast, the serum concentrations of CD and D displayed a significant rise by 30 minutes, reached a peak after 90 minutes, but had not returned to fasting levels after 150 minutes. The serum bile acid responses after a meal suggest that there is considerable absorption of dihydroxy bile acids in the proximal small intestine in man.