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Results for “Germ-Free Life”

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At least 19 recordsLinked to original sources
PubMed1976

The histochemistry of mucosaccharides in some organs of germfree rats.

In order to study the histochemical nature of mucosaccharides in germfree animals, the organs in natural contact with bacteria (stomach, small and large intestine) and those naturally remote from bacteria (tracheal and ear cartilage and aorta) were studied by means of light microscopic methods for mucosaccharides in germfree and conventional rats. In the stomach (surface and foveolar cells) of germfree rats the histochemical reactions for acid and neutral mucosaccharides were apparently less intense than in that of conventional rats, whereas in the small and large intestine (goblet cells) of germfree rats the reactions were significantly more intense than in those of conventional rats. In the cartilage (intercellular matrix, lacunar border and chondrocyte cytoplasm) and aorta (interelastic spaces) of germfree animals the reactions were less intense than in those of conventional animals. In addition, some differences in the histochemical nature of mucosaccharides between the organs of germfree and conventional rats were noted, as revealed by the effects of chemical modifications and digestions with enzymes upon the histochemical reactions studied.

Animals↗
PubMed1979

Pathogenesis of diarrhoea caused by astrovirus infections in lambs.

Experimental infection of 2-day-old gnotobiotic lambs with lamb astrovirus produced mild diarrhoea after an incubation period of about 48 hours. No other clinical symptoms developed. Infection was studied by immunofluorescent and histological examination of tissues from the lambs. Astroviruses infected only mature villus epithelial cells and subepithelial macrophages in the small intestine, where they produced partial villus atrophy. Infected enterocytes were replaced with cuboidal cells from the crypts, and the lesion gradually healed by 5 days after infection. No serological relationship was detected by immunofluorescence between lamb astrovirus antigen in gut sections and antisera to either calf or human astrovirus.

Animals↗
PubMed1979

Changes in ovarian activity during hepatocarcinogenesis by N-2-fluorenylacetamide: role of alpha-fetoprotein.

During chemical hepatocarcinogenesis by N-2-fluorenylacetamide, the hormonal status of female Sprague Dawley rats is largely modified. Ovaries present a reduced activity which is evidenced by a decreased number of follicles and corpora lutea. The level of progesterone in N-2-fluorenylacetamide treated rats is low and agrees with the lack of corpora lutea. Conversely, estradiol level remains normal. This fact may be explained by the presence of alpha-fetoprotein, a carcino-embryonic protein which binds specifically estrogenic hormones.

2-Acetylaminofluorene↗
PubMed2024

Salmonella Typhimurium screen identifies shifts in mixed-acid fermentation during gut colonization.

How enteric pathogens adapt their metabolism to a dynamic gut environment is not yet fully understood. To investigate how Salmonella enterica Typhimurium (S.Tm) colonizes the gut, we conducted an in vivo transposon mutagenesis screen in a gnotobiotic mouse model. Our data implicate mixed-acid fermentation in efficient gut-luminal growth and energy conservation throughout infection. During initial growth, the pathogen utilizes acetate fermentation and fumarate respiration. After the onset of gut inflammation, hexoses appear to become limiting, as indicated by carbohydrate analytics and the increased need for gluconeogenesis. In response, S.Tm adapts by ramping up ethanol fermentation for redox balancing and supplying the TCA cycle with α-ketoglutarate for additional energy. Our findings illustrate how S.Tm flexibly adapts mixed fermentation and its use of the TCA cycle to thrive in the changing gut environment. Similar metabolic wiring in other pathogenic Enterobacteriaceae may suggest a broadly conserved mechanism for gut colonization.

Animals↗
PubMed2024

Exclusive enteral nutrition initiates individual protective microbiome changes to induce remission in pediatric Crohn's disease.

Exclusive enteral nutrition (EEN) is a first-line therapy for pediatric Crohn's disease (CD), but protective mechanisms remain unknown. We established a prospective pediatric cohort to characterize the function of fecal microbiota and metabolite changes of treatment-naive CD patients in response to EEN (German Clinical Trials DRKS00013306). Integrated multi-omics analysis identified network clusters from individually variable microbiome profiles, with Lachnospiraceae and medium-chain fatty acids as protective features. Bioorthogonal non-canonical amino acid tagging selectively identified bacterial species in response to medium-chain fatty acids. Metagenomic analysis identified high strain-level dynamics in response to EEN. Functional changes in diet-exposed fecal microbiota were further validated using gut chemostat cultures and microbiota transfer into germ-free Il10-deficient mice. Dietary model conditions induced individual patient-specific strain signatures to prevent or cause inflammatory bowel disease (IBD)-like inflammation in gnotobiotic mice. Hence, we provide evidence that EEN therapy operates through explicit functional changes of temporally and individually variable microbiome profiles.

Crohn Disease↗
PubMed1975

Eimeria falciformis (Eimer, 1870) in specific pathogen free and gnotobiotic mice.

The endogenous and exogenous stages of a species of murine Eimeria were examined and compared with descriptions of other species isolated from Mus musculus. Developing stages of the parasite were found in the epithelial cells of the caecum and colon. Three asexual generations were observed, the third becoming apparent on the fourth day concurrently with gametogeny. The total length of the prepatent period was 5 days. Oocysts of the coccidian, identified as Eimeria falciformis, were administered to a group of germfree mice. Despite a dose level of 1 x 10(6), the coccidium was not established. Histological examination indicated the failure of the sporozoite to penetrate its host epithelium. The possible causes of this phenomenon were discussed.

Animals↗
PubMed1977

The importance of Lactobacilli in maintaining normal microbial balance in the crop.

1. The effect of lactobacilli on Escherichia coli has been examined in vitro and in chicken crop in vivo. 2. Inhibition of E. coli was dependent on the presence of sufficient numbers of lactobacilli. 3. In a standard test some lactobacilli were bacteriostatic and one was bactericidal. The bacteriostasis was due to the low pH produced by these strains but bactericidal activity could not be accounted for by pH alone. 4. In gnotobiotic animals the bactericidal strain was no more inhibitory for E. coli than was a bacteriostatic strain.

Animals↗