Reliable sampling method for analysis of the ecology of the human alimentary tract

An intubation method has been developed that allows removal of a sample of human intestinal fluid within a short period of time, that avoids contamination, and that minimizes exposure of the sample to air. Preliminary results obtained with this method have shown that the stomach and duodenum are essentially sterile and that the bacterial population present in the remainder of the small intestine is similar to that described by previous workers except that Veillonella species were encountered frequently and Haemophilus species were also detected in the lower jejunum and ileum of some individuals.     

Methylation analysis of the major gangliosides of the human alimentary mucosa.

The five major gangliosides of the human alimentary mucosa were purified with silicic acid column chromatography and with thin-layer chromatography. The linkages in the carbohydrate portion were analysed by permethylation with gas chromatography-mass spectrometry. A succesful analysis of the linkages of two hematosides and three tetraglycosylceramides was performed. Two of the tetraglycosylamides had a galactosamine in their chain and one had a glucosamine.     

Uptake of amplifiable fragments of retrotransposon DNA from the human alimentary tract

Few attempts have been made to study the transfer of DNA from ingested food across the intestinal barrier. A low uptake of ingested DNA has been observed in mice, cattle and poultry. There have been no reports on humans so far. Maintenance of species barriers, protection against retrotransposons, optimisation of oral DNA vaccines and the fate of genetically modified foodstuffs are issues where this topic is of importance. We therefore used the high-copy-number rabbit retrotransposon RERV-H, and rabbit mitochondrial DNA, to study the transfer of DNA from ingested rabbit meat into the bloodstream of two human volunteers. A quantitative PCR was used to measure RERV-H levels in food and in the blood. Amplification with the primers selected results in the generation of a 250-bp fragment of RERV-H. Transfer across the intestinal epithelium could be demonstrated in both subjects. Levels of the fragment in the bloodstream peaked at 1–3 h after ingestion of the experimental meal. One hour after a meal of rabbit meat containing 10¹⁴ copies of RERV-H DNA, a maximum concentration of 200 copies of RERV-H DNA per ml of peripheral blood was observed, which corresponds to the uptake of approximately 10⁶ RERV-H DNA copies in 1 h. RERV-H DNA was detected in both cellular and plasma compartments. Both rabbit retrotransposon and mitochondrial DNA was taken up from the human alimentary tract. The size of the fragments detected is similar to that of SINE retrotransposons (approximately 300 bp). The fate and functionality of alimentary DNA in humans will require further study.Communicated by W. Goebel     

Growth of the alimentary tract with aging in chickens.

There is a mathematical model supporting that when growth rate of the chickens is maximized and not constrained by the food-availability, the optimal relationship between body mass and alimentary tract mass should conform to a two-segmented straightened line with different slopes. In the present work we have studied the model using the mass of the intestines as an indicator of growth of the alimentary tract of the Gallus gallus domesticus L. We have observed the slope change of the two segments around a body weight of 90 g that corresponded to two-week-old animals and, at this age it was supposed that the differentiation of the intestine reach the maximum.     

Embryology of the sheep. II. The alimentary tract and associated glands

The day-by-day development of the alimentary system of the sheep embryo from 14 to 34 days is documented and described. This includes development of the mouth, the pharynx and its derivatives, esophagus, stomach, intestine, cecum, pancreas and liver. This work provides standards within the normal range of development of the ovine alimentary system on which studies of abnormal development can be based.     

Calcitonin-like immunochemical staining in the alimentary tract of Ciona intestinalis L.

Summary Calcitonin-like immunoreactivity has been found with the peroxidase-anti-peroxidase (PAP) method in cells of the epithelium of the alimentary tract as well as in nerve cells and nerve fibers in the connective tissue underlying the epithelium of the alimentary tract of Ciona intestinalis L. The nature of these cells is discussed with reference to endocrine-like cells found in the alimentary tract of other protochordates and to the possible dual role of calcitonin occurring in the gastroenteropancreatic system, on the one hand, and in the nervous system, on the other.     

Immunohistochemical distribution of hepatic fatty acid-binding protein in rat and human alimentary tract

Tissues from rat and human alimentary tract were immunostained with rabbit antibodies to fatty acid-binding protein (FABP) isolated from rat liver, since the precise immunohistochemical localization of the protein in gut has not been determined. The results obtained indicated that FABP immunoreactivity was found almost exclusively in intestinal absorptive cells, the sole exception being its presence in the cytoplasm of a few goblet cells. In small bowel, FABP-positive cells were most often found in the upper and middle segments, and less frequently in the lower to terminal portion. Immunoreactive cells were also found in large bowel of rat and human, but with differing patterns of distribution. In rat, positive cells were found mainly in the lower portion of the large intestine, whereas in human positive cells were present in all portions. Immunoreactive cells were detected in rat and human cecum, in the upper half of human rectum, and in human vermiform appendix. No such cells were found in esophageal and nonmetaplastic gastric mucosa or in pancreatic tissue, whereas they were present in great numbers in metaplastic gastric mucosa. The results of this study therefore suggest that FABP is a useful marker for research into the physiology or pathology of absorptive cells in the gastrointestinal tracts of both species.     

Reliable amplification method for bacterial RNA

DNA microarray technology has been increasingly applied for studies of clinical samples. Frequently, RNA probes from clinical samples are available in limited amounts. We describe a reliable amplification method for bacterial RNA. We verified this method on mycobacterial RNA applying mycobacterial genome-directed primers (mtGDPs). Glass slide-based oligoarrays were employed to assess the quality of the amplification method. We observed a relatively small bias in amplified RNA pool when compared to the unamplified one. Up to 1000-fold linear RNA amplification in a single amplification round was obtained. To our knowledge, this study describes the first amplification method for mycobacterial RNA.     

Colonization of R plasmid-bearing Escherichia coli strains in the mouse alimentary tract.

In order to examine the ability of R plasmid-bearing Escherichia coli strains to colonize in the mouse alimentary tract, an R plasmid-positive (R(+)) E. coli strain and its R plasmid-negative (R(-)) counterpart were together inoculated into the streptomycin-treated mouse alimentary tract, and the numbers of fecal E. coli strains were enumerated. The numbers of R(+) strains were always at the level similar to or lower than those of their counterparts and rapidly decreased in the fecal population. However, when R plasmids, which were originated from a cryptic plasmid of the host E. coli strain, were utilized, an R(+) strain dominated over its R(-) counterpart during the experimental period. These experimental results indicated that the relationship between the host strain and R plasmids affected the ability of the host strain to colonize in the alimentary tract.     

Inability of human clinical strains of Helicobacter pylori to colonize the alimentary tract of germfree rodents

Several attempts were made to colonize the alimentary tract and infect germfree BALB/c mice and germfree Sprague-Dawley rats with two human isolates of Helicobacter pylori. The alimentary tracts of mice, sacrificed at intervals between 1 day and 20 weeks after oral challenge, were culture negative for H. pylori. The alimentary tract, kidney, liver, and mesenteric lymph nodes were culture negative for H. pylori 5 h after intravenous challenge. Growth of H. pylori was inhibited by homogenates of murine stomach, small intestine, liver, and mesenteric lymph nodes. Germfree rats and mice do not appear to be readily colonized or infected by human strains of H. pylori.