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Biomedical subjects

J P Koopman

Publications and source records attributed to J P Koopman.

At least 55 records · Page 3Linked to original sources
PubMed1986

Internal exposure of rats to benzidine derived from orally administered benzidine-based dyes after intestinal azo reduction.

The role of the rat intestinal flora in the azo reduction of some benzidine-based dyes was studied in vitro and in vivo. The formation of benzidine was measured after anaerobic incubation of direct black 38, direct blue 6 and direct brown 95 in the presence of caecal bacteria in vitro. Benzidine was absorbed from the intestinal tract much better than the parent compounds. Oral administration of direct black 38 or direct brown 95 to Wistar rats results in the urinary excretion of mutagens. After oral administration of these dyes to germ-free Wistar rats no mutagenicity was observed in urine. The present results show that after oral administration, reduction by the intestinal flora should be considered as the first essential step in the biotoxification of benzidine-based dyes.

Administration, Oral↗
PubMed1986

Appearance and reappearance of mutagens in urine from rats after oral administration of direct brown 95, due to coprophagy.

Rats treated orally with direct brown 95, a benzidine-based dye, widely used in dyeing of textiles, plastics, paper and other materials, showed 2 peaks of excretion of mutagenic products in urine, one between 6 h and 18 h after administration and one about 30 h later. Prevention of coprophagy by fitting neck collars resulted in the disappearance of the second peak. Oral administration of carminic acid resulted in a biphasic excretion of this dye in the feces, due to coprophagy. The excretion pattern of mutagens in urine after administration of direct brown 95 corresponds with the excretion pattern in the feces of orally administered carminic acid.

Administration, Oral↗
PubMed1986

'Normalization' of germfree mice after direct and indirect contact with mice having a 'normal' intestinal microflora.

Germfree mice were associated via direct and indirect contact with a 'normal' microflora by placing 'normal' mice in an isolator with germfree mice. Relative caecal weights, the ratio of secondary to primary bile acids, the presence of filamentous segmented bacteria in the small intestine and faecal beta-aspartylglycine were normal 5 days after direct contact and 15 days after indirect contact. Enterobacteriaceae were demonstrated by the third day after direct contact and the fourth day after indirect contact. Volatile and non-volatile fatty acids in the caecal contents were variable and appeared to be unrelated to the 'normalization' process of germfree mice after association with a microflora.

Animals↗
PubMed1985

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.

Animals↗
PubMed1984

[Resistance to colonization of the gastrointestinal tract].

The microflora naturally present in the intestinal tract of mammals and birds will ensure that pathogenic bacteria will not become colonized or will have difficulty in doing so and cannot grow into large populations in the intestinal tract. This phenomenon is termed 'colonization resistance'. The microflora of the animals is transmitted from parents to offspring and is species-specific. When contacts between parent animals and young animals are broken off, the young are colonized by an adventitiously present microflora which possesses only part of the favourable characteristics. A high pressure of infection by pathogenic bacteria, poor general resistance, the use of antibiotics, fasting, variations in the diet and stress also are factors which usually have an adverse effect on the microflora present in the host. In addition, age is a factor. Young animals relatively often show disturbances of the intestinal flora. The animals are particularly susceptible to intestinal disease immediately after weaning. Methods are suggested, by which disturbances of the intestinal flora due to the above may be prevented.

Age Factors↗
PubMed1984

Protection of chicks against Salmonella infantis infection induced by strict anaerobically cultured intestinal microflora.

In two experiments newly hatched broilers were orally inoculated either with intestinal microfloras cultured under different conditions or with a suspension of intestinal homogenate and challenged with high doses (3 X 10(5) c.f.u. per chick) of Salmonella infantis organisms. Inocula were prepared from intestinal material of mature SPF WL hens under aerobic or strictly anaerobic conditions (less than 5 ppm oxygen), and protected against atmospheric oxygen during storage. A very significant reduction of the number of Salmonella infantis bacteria in caecal content was achieved one and two weeks after challenge in those groups of chicks which were inoculated with anaerobically cultured flora or with intestinal homogenate. In order to induce protection, obligate anaerobes had to be accompanied by facultative anaerobes. Amprolium or Monensin dit not interfere with protection. Protection induced by intestinal microflora depends on anaerobiosis during preparation, culturing, storage, and application of the protective bacteria. Starvation on the first day of life appeared to have a negative effect on protection.

Anaerobiosis↗
PubMed1984

Protection of chicks against salmonella infection induced by spray application of intestinal microflora in the hatchery.

The efficacy of spray application of intestinal microflora of the adult bird in protection of broilers against salmonella infections was studied in 3 experiments under laboratory and field conditions. In chicks treated soon after hatching (in the hatchers at approximately 30 per cent hatch or in the chick delivery boxes in the hatchery) with crop-caecum homogenate or a mixture of aerobically and strict anaerobically cultured intestinal flora, very good results were achieved. A very obvious protective effect against a high infection dose (3 X 10(6) c.f.u.S. infantis bacteria per chick) and complete protection against natural infection with different salmonella types was induced. A significant improvement of growth rate was observed in broilers treated by spray in the hatchery and reared for 7 weeks under field conditions in an environment heavily contaminated with different salmonella types.

Animals↗
PubMed1984

Tail lesions in C3H/He mice.

C3H/He mice obtained from different suppliers developed tail lesions shortly after arrival. Histologically no inclusion bodies could be shown. A serological survey of diseased mice was negative for those viruses which may cause skin lesions. The disease could not be transmitted to healthy mice and no virus could be cultured from the skin lesions. It is concluded that the syndrome was induced by stress, in this case transport from the United Kingdom to the Netherlands.

Animals↗
PubMed1984

'Normalization' of germfree mice with anaerobically cultured caecal flora of 'normal' mice.

Germfree (GF) mice were inoculated with a cultured flora from 10(-1), 10(-3), 10(-5), and 10(-7) dilutions of caecal contents from a 'normal' mouse. GF mice associated with a flora of a 'normal' mouse served as controls. The following intestinal parameters were determined: Colonization resistance (CR), Relative caecal weight (RCW), villus:crypt ratio (jejunum and ileum), IgA-producing cells (jejunum and ileum), beta-aspartyl glycine (faeces), volatile and non-volatile fatty acids (caecum) and bile acids (faeces). Only the 10(-1) culture was able to induce similar changes in the GF mice to a 'normal' flora. The GF + 10(-5) and GF + 10(-7) groups deviated markedly from the controls while the GF + 10(-3) group showed in general intermediate values between GF + SPF and GF + 10(-1) on the one hand and GF + 10(-5) and GF + 10(-7) on the other hand. beta-aspartyl glycine was present only in the GF + 10(-7) group. Scanning electron microscopy (SEM) of ileal contents revealed segmented filamentous organisms in the ileum of controls and the GF + 10(-1) group. The faecal flora consisted mainly of fusiform organisms. In the faeces of the 10(-5) and 10(-7) groups increasing amounts of non-bacterial matter were found, while in the faeces of the other groups virtually only bacteria were seen.

Anaerobiosis↗