Biomedical subjects
Publications and source records attributed to J P Koopman.
Streptobacillus moniliformis was isolated from the middle ear of 9 of 16 rats used for otological studies. Examination of rat sera for the presence of anti-Streptobacillus moniliformis antibodies using an ELISA technique resulted in 15 seropositive animals. The source of the S. moniliformis infection was not determined.
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To obtain a suitable species-specific microflora for a new rat SPF-unit, germ-free WAG/Rij rats were associated with a flora derived originally from selectively decontaminated Cpb: WU (Wistar) rats. Caecal and ileal contents of these rats had been cultured anaerobically (37 degrees C) for 7 days and harvested. This cultured flora was given to germ-free Cpb: SE (Swiss) mice, which were kept in an isolator system and acted as a source of the flora to associate germ-free Wag/Rij rats. In these associated rats, several parameters indicative of the 'quality' of the intestinal microflora were investigated and compared to those in rats with a mouse derived anaerobic microflora. Parameters included relative caecal weight, colonization resistance and the concentration of faecal bile acids. The cultured rat-derived microflora normalized the observed intestinal parameters better than the mouse derived microflora, and provided better colonization resistance. We conclude that culturing of intestinal contents of selectively decontaminated animals can be a useful way to obtain a species-specific donor-microflora which can be used to start new SPF units.
The effects of litter size and availability of solid feed before weaning on the growth mice were studied. Pups of small litters (n = 3) grew significantly faster than mice of large litters (n = 10), the mean difference at weaning being about 3 g. The difference in body mass persisted after weaning; at the age of 98 d the mean difference was about 5 g. Availability of solid feed to pre-weaned mice significantly stimulated mass gain of litters consisting of 10 but not of 3 pups. Body masses of the dams during the suckling period were markedly influenced by litter size: Mice with 10 pups had increased body masses when compared with mice having 3 young. By the time of weaning, body masses of mothers with larger or small litters had become similar again just as they were immediately after parturition.
The microflora of the gastro-intestinal tract of dystrophic BIO 8262 Nij Syrian hamsters and Kun:Sh Syrian hamsters as controls was investigated by means of culturing techniques and scanning electron microscopy. The oesophagus, forestomach, stomach, small intestine, coecum and faeces were assessed for the presence of Enterobacteriaceae, Staphylococci, Lactobacilli, Streptococci, Clostridia, Bacteroides and yeasts. The normal hamsters showed low levels of yeasts in the oesophagus, forestomach and stomach; yeasts were not present in the other compartments. Relatively low levels of Staphylococci and Enterobacteriaceae were found in all gut segments; also Bacteroides was found in low levels in the upper part of the gut. The other groups of bacteria showed relatively high levels in all segments. In dystrophic BIO 8262 Nij hamsters no Enterobacteriaceae and yeasts have been detected in the gut. Scanning electron microscopy showed no difference in adhesion between both hamsters strains.
Ivermectin administered to rabbits in drinking water (3 ml of drenching liquid (0.08% w/v ivermectin) per litre of drinking water) for one of five days, gave rise to blood levels persisting on several days and were measured by the death of mosquitoes following a meal of blood from these animals. In practice ivermectin (3 ml/l) was administered to 98 rabbits on a rabbit-meat farm for 24 hours. This treatment was repeated within a fortnight. The degree of ear mange was determined by the amount of incrustation. Within three weeks after treatment was initiated, all animals were free of crusts. Incrustation gradually recurred during the following weeks. After 161 days, approximately ten per cent of the animals showed some incrustation again. Treatment with ivermectin once every six months is advised to suppress ear mange.
In a mouse model the effects of environmental stress on gastrointestinal parameters and the effects of cheese-whey on the changes induced by stress were studied. Mice were subjected to overcrowding, lack of bedding, overcrowding together with lack of bedding, continuous light, and housing at 30 degrees C. The influence of stress on relative caecal weight, faecal enterobacteriaceae, colonisation resistance (CR), filamentous segmented bacteria in the small intestine, fusiform bacteria in the faeces, and concentration of faecal bile acids was studied. Stress had no influence on relative caecal weight, faecal enterobacteriaceae, and faecal bile acids. Stress did decrease colonisation resistance, presence of segmented filamentous bacteria in the small intestine, and fusiform bacteria in the faeces. Cheese-whey had no positive effect on the microbiological disturbances caused by stress. The number of filamentous segmented bacteria in the small intestine and fusiforms in the faeces decreased by giving cheese-whey.
Hysterectomy-derived germ-free guineapigs were given colonization-resistant caecal flora from mice (mCRF) or microflora obtained from the caecum of an antibiotic-decontaminated conventional guineapig (gpCRF) and compared with guineapigs raised conventionally with the sow. Body weight and the following intestinal parameters were determined for the groups: colonization resistance (CR) to Escherichia coli, relative caecal weight (RCW), beta-aspartylglycine (faeces), volatile fatty acids (caecum) and bile acids (faeces). mCRF guineapigs showed values quite different from control animals for CR and RCW, indicating the unsuitability of mouse CRF for normalizing guineapigs. In gpCRF guineapigs CR and RCW values were comparable with controls, indicating the suitability of the guineapig flora for normalizing guineapigs. mCRF guineapigs housed with gpCRF guineapigs, showed an improvement in CR and RCW, yielding values found in control animals.
The aim of this study was to investigate methods to eliminate pathogenic viral agents while preserving the 'normalizing' properties of the gut microflora of mice. Mouse hepatitis virus A59 (MHV), Reo 3 virus and Theiler GD VII virus were added to the caecal contents of 'normal' mice and following dilution, with or without subsequent culturing, given to germ-free mice. Four weeks later antibody titres against these and other viruses were determined. MHV and Theiler CD VII virus survived dilution but were eliminated during culturing. Reo-virus survived the 10(-1) dilution-culture step. All dilutions and dilution-cultures of caecal contents resulted in 'normalization' in germ-free recipients of the relative caecal weight, percentage faecal fusiform-shaped bacteria, faecal bile acids and colonization of small intestine by segmented filamentous bacteria.
Liver cholesterol concentrations were measured in mice after feeding for 30 days cholesterol-free, semipurified diets containing various sources of fat, carbohydrates or fiber. Olive oil produced significantly higher liver cholesterol concentrations than tallow, sunflowerseed oil and cocoa fat. In mice fed either fructose or sucrose liver cholesterol was significantly increased when compared with mice fed galactose or lactose. Dietary cellulose, when compared with pectin, did not influence liver cholesterol. The amount of fat in the diet, in the form of either corn oil or coconut fat, had no significant effect on liver cholesterol. It is concluded that the type of carbohydrate and fat in the diet are major determinants of liver cholesterol in mice.
The effect of pellet hardness on growth of pre-weaned mice was studied with the use of a specially constructed cage so that lactating females and their young could be fed separately. Diet pellets with identical ingredient composition but hardness of either 20 or 40 kp were prepared. Growth of the young not supplemented with feed was markedly depressed by the feeding of the 40-kp diet to the mothers, when compared with the 20-kp diet. If the young of mothers fed the 40-kp diet had free access to diet pellets with hardness of either 20 or 40 kp, their growth performance improved. When the breeding females were fed the 20-kp diet, feed supplementation of the young did not affect their body weight. This study suggests that the observed effect of diet pellet hardness on body weight of pre-weaned mice is mediated in part through the mothers. Free access to feed was found to stimulate growth of pre-weaned mice only if the mothers were fed extremely hard diet pellets.
The hardness of 3 commercial diet pellets for laboratory rats and mice was studied. Hardness was measured as the force (kp) required to crush a diet pellet. Between-batch variation, expressed as coefficient of variation, ranged between 12 and 70%. In one type of diet hardness of the pellets varied between 4 and 50 kp. Hardness did not change during storage for a period of 8 weeks. To investigate the effect of hardness on growth performance of young mice experimental diets were prepared with identical ingredient composition but with hardness of either 15 or 45 kp. Female mice provided with hard pellets (45 kp) were not able to raise their litters. Feeding the experimental diet as 15 kp pellets resulted in a slightly retarded growth when compared with the experimental diet in the form of meal. Weaned mice were fed with the experimental diet in 4 different forms: meal, 15 kp, 45-kp and ground 45-kp pellets. Male mice, unlike females, fed the 45-kp diet grew slower than their counterparts fed the other diet forms. It is concluded that batches of extremely hard pellets may be occasionally delivered, and that such diets have undesirable effects on performance of young mice.
Hysterectomy-derived germ-free (GF) rabbits were given strictly anaerobic microflora obtained from the caecum of an antibiotic-decontaminated conventional rabbit. One group was given the caecal flora diluted in doe's milk. The second group received caecal flora without doe's milk and administration of the flora was repeated when the animals were given pelleted diet. Body weight and intestinal parameters determined in the two groups of rabbits were compared with values in rabbits conventionally raised with the doe. In GF rabbits given caecal flora, the values for most intestinal parameters were similar to values recorded in conventional animals. However colonization resistance to Escherichia coli was limited in GF rabbits given caecal flora diluted in doe's milk and severely impaired in GF rabbits given caecal flora without doe's milk, although relative caecal weight was normal. It is concluded that enteric microfloras should be preferably incorporated in doe's milk when dosed to GF rabbits to obtain acceptable gastrointestinal "normalization".
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A colony of mice that do not harbor lactobacilli in their digestive tracts but whose intestinal microflora is otherwise functionally similar to that of conventional animals was derived. Methods used to reconstitute the intestinal microflora of the mice included inoculation of the animals with cultures of specific microbes, noncultivable microbes attached to epithelial cells, and cecal contents from conventional mice treated with chloramphenicol. Twenty-six microflora-associated characteristics were monitored by using relatively simple tests to determine the microflora status of the mice.
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Scanning electron micrographs are presented of the ileal epithelium of mice aged 5, 15, 20 and 25 days. During this period the villous pattern develops to full maturity. By the twentieth day of life a segmented filamentous micro-organism colonizes the ileal epithelium and is firmly attached via a small segment. During the first days of colonization the segmented filamentous micro-organisms themselves are subcolonized by small rod-shaped bacteria, presumably lactobacilli. At the age of 25 days this subcolonization was no longer observed.