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Biomedical subjects

A C Beynen

Publications and source records attributed to A C Beynen.

At least 289 records · Page 16Linked to original sources
PubMed1990

An alternative method for the quantitative collection of faeces and urine of cats as validated by the determination of mineral balance.

Generally, in order to collect faeces and urine of cats, the animals are housed in metabolism cages with wire-mesh bases. We have developed an alternative method to collect faeces and urine quantitatively and separately, using cages with solid floors. The use of such cages allows long-term experiments to be carried out without increased risk for injury to feet or legs. Modified litter boxes were constructed so that faeces and urine were separated and the cats could bury their faeces. With the use of this method the excretion of calcium, magnesium and phosphorus by mature cats was determined. Mineral retention over a period of ten days did not differ significantly from zero, suggesting that the method developed is valid for the measurement of mineral excretion. Evidence is presented that under our experimental conditions faeces should be collected for at least five days so as to cancel out largely the impact of day-to-day variation in defecation on the variance of mineral retention.

Animal Welfare↗
PubMed1990

Effects of group size and gentling on behaviour, selected organ masses and blood constituents in female Rivm: TOX rats.

The effects of group size (individually versus 3 in a cage) and gentling on behaviour and blood constituents were studied in female rats. Gentled rats showed less freezing and/or escaping when approached in an objective handling test than non-gentled rats; the type of caging had no significant influence. In a small field, gentled rats displayed significantly more turning and standing upright, whereas these parameters did not differ between rats housed either individually or three in a cage. In both tests, gentled rats produced significantly less urine than did control rats. Neither caging nor gentling significantly influenced the group mean values and variance of masses of adrenals, spleen and thymus and plasma concentrations of glucose, cholesterol, triglycerides and corticosterone. Removal of a cage from the rack and getting out a rat caused increase in plasma concentrations of corticosterone in its remaining cage mates.

Animal Husbandry↗
PubMed1990

Availability of solid feed and growth rates of pre-weaned mice of different litter size.

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.

Animal Feed↗
PubMed1990

Liver cholesterol concentrations in rats fed diets containing various fats of plant origin.

Plasma and liver cholesterol concentrations were measured in rats fed high-cholesterol (1%, w/w), semipurified diets containing various fats of plant origin. Palm oil produced significantly higher plasma cholesterol concentrations than soybean oil, rapeseed oil, coconut fat and palm kernel oil. The content of liver cholesterol in rats fed rapeseed oil was significantly higher than in rats fed the other fats except for soybean oil. When comparing the fatty acid compositions of the fats used, this study suggests that oleic acid induces higher liver cholesterol concentrations than linoleic acid.

Animals↗
PubMed1990

Daily change of cage depresses mass gain in mice.

The effect of daily cage changing versus no changing for a period of 2 weeks was studied in female and male NMRI:Cpb mice. The animals were subjected to either true or sham cage changing so as to balance for possible effects of handling. Daily cage changing significantly reduced mass gain in female and male mice. It is suggested that the frequency of cage changing should be kept constant both within and between experiments.

Animals↗
PubMed1989

Immunochemical quantitation of fatty-acid-binding proteins. I. Tissue and intracellular distribution, postnatal development and influence of physiological conditions on rat heart and liver FABP.

Antisera against rat heart and liver fatty acid-binding protein (FABP) were applied in Western blotting analysis and ELISA to assess their tissue and intracellular distribution, and the influence of development, physiological conditions and several agents on the FABP content of tissue cytosols. The data obtained are compared with the oleic acid-binding capacity. Heart FABP is found in high concentrations in heart, skeletal muscles, diaphragm and lung, and in lower concentrations in kidney, brain and spleen, whereas liver FABP is limited to liver and intestine. In heart and liver, FABP is only present in the cytosol. The FABP content of both heart and liver shows a progressive increase during the first weeks of postnatal development, in contrast to their constant oleic acid-binding capacity. The reciprocally declining alpha-fetoprotein content of both tissues may partially account for the complementary fraction of the fatty acid-binding capacity. The FABP content and the fatty acid-binding capacity of adult heart and liver were in good accordance under various physiological conditions. Addition of clofibrate to the diet induces an increase of liver FABP content, whereas feeding of cholesterol, cholestyramine, mevinolin or cholate caused a marked decrease. The significance of the combined determination of fatty acid-binding capacity and FABP content (by immunochemical quantitation and blotting analysis) is indicated.

Animals↗
PubMed1989

Increased concentrations of liver cholesterol in rats fed lactulose.

The disaccharide lactulose (beta-D-galactopyranosyl-(1-4)-D-fructofuranose) is thought to be poorly hydrolized by intestinal enzymes but is broken down by microorganisms in the colon. Thus lactulose shares with pectin similar characteristics. Lactulose is used in the food industry and in the treatment of constipation. There is preliminary evidence that dietary lactulose (5%, w/w) causes increased concentrations of serum and liver cholesterol in rats when compared with pectin. This paper describes dose-response relationships between dietary lactulose and cholesterol in either serum or liver.

Animals↗
PubMed1989

Lack of effect of dietary minerals on liver cholesterol concentrations in rats.

Female rats were fed cholesterol-free, purified diets with different concentrations of calcium (0.13-0.75%, w/w), magnesium (0.02 or 0.04%) or phosphorus (0.2-0.8%) as the only dietary variable. After 28 days, no effects of the minerals were found on liver cholesterol concentrations and rates of fecal excretion of bile acids.

Animals↗
PubMed1989

Plasma esterase-1 (ES-1) activity is increased in rats fed high-fat diets.

The question addressed is whether the amount and type of dietary fat affects esterases in plasma. Rats were fed semipurified diets containing 2.0 to 19.4% (w/w) of fat in the form of coconut fat or corn oil. Fat was added to the diets at the expense of isocaloric amounts of carbohydrates. Plasma total esterase activities measured with 4-nitrophenylacetate as substrate were slightly increased with increasing fat intakes. However, an increase in fat concentration of the diet was associated with a pronounced increase in the activity of the so-called ES-1 isozyme in plasma. ES-1, which represents very little plasma total esterase activity, was quantified densitometrically as the high-mobility, anodal esterase band on polyacrylamide gel electrophoresis. The positive association between amount of dietary fat and ES-1 activity was identical for coconut fat and corn oil.

Animals↗
PubMed1989

Sterol balance and cholesterol absorption in inbred strains of rabbits hypo- or hyperresponsive to dietary cholesterol.

In 2 inbred strains of rabbits with high or low response of plasma cholesterol to dietary cholesterol, excretion of steroids in the feces and efficiency of cholesterol absorption were determined. Rates of whole-body cholesterol synthesis, measured as fecal excretion of bile acids and neutral steroids minus cholesterol intake, were similar in hypo- and hyperresponders fed a low-cholesterol (8 mumol/100 g) diet. Transfer of the rabbits to a high-cholesterol (182 mumol/100 g) diet caused an increase in fecal bile acid excretion in hypo- but not in hyperresponders. Dietary cholesterol did not affect neutral steroid excretion in either rabbit strain. Hyperresponders tended to accumulate more cholesterol in their body than did hyporesponders. After the rabbits were switched back from the high- to the low-cholesterol diet, rates of whole-body cholesterol synthesis were significantly higher in the hypo- than in the hyperresponders. With the use of the simultaneous oral administration of [3H]cholesterol and beta-[14C]sitosterol, hyperresponders were found to absorb significantly higher percentages of cholesterol than hyporesponders. It is concluded that the differences in stimulation of bile acid excretion after cholesterol feeding and the efficiency of cholesterol absorption are important determinants of the phenomenon of hypo- and hyperresponsiveness in the 2 inbred rabbit strains.

Animals↗
PubMed1989

Digestibility of casein, formaldehyde-treated casein and soya-bean protein in relation to their effects on serum cholesterol in rabbits.

Adult male rabbits were fed on semi-purified diets containing soya-bean protein isolate, casein or formaldehyde-treated casein as the protein source and 1 g cholesterol and 5 g of the non-absorbable marker chronic oxide/kg diet. The concentration of cholesterol in serum and in liver was increased on both the casein and formaldehyde-treated-casein diets. Excretion of bile acids and their concentration in faeces were lower in rabbits fed on casein or formaldehyde-treated casein when compared with rabbits fed on soya-bean protein. Apparent digestibility of nitrogen was lowest when formaldehyde-treated casein was fed, and highest on the casein diet. In rabbits fed on casein treated with formaldehyde, higher proportions of N were found in the water-soluble and trichloroacetic acid-insoluble protein fractions of the gastrointestinal tract contents compared with rabbits on the other two diets. Absorption of phosphate from the gastrointestinal tract was higher in rabbits fed on casein than in rabbits fed on soya-bean protein or formaldehyde-treated casein. The results indicate that, in rabbits, protein digestibility may not be an important determinant of serum cholesterol.

Animals↗
PubMed1989

Lecithin intake and serum cholesterol.

To find out whether the consumption of lecithin has a more beneficial effect on serum cholesterol than does the consumption of equivalent amounts of polyunsaturated oils, we scrutinized 24 studies on the effect of supplementary lecithin intakes ranging from 1 to 54 mg/d. Most of the studies lacked an appropriate control group, had a small sample size, or had changes in intake of other foods because of increased energy intake from lecithin. In only four trials were attempts made to balance fatty acid intakes of control and experimental groups. There is no evidence for a specific effect of lecithin on serum cholesterol independent of its linoleic acid content or secondary changes in food intake. The observed lecithin-induced hypocholesterolemic effects found in various studies were artifacts caused by the design and the manner of data analysis, were mediated by other dietary changes, or were due to the linoleic acid present in lecithin.

Cholesterol↗
PubMed1989

Phosphorus-induced nephrocalcinosis and kidney function in female rats.

The question was addressed whether dietary phosphorus-induced nephrocalcinosis in rats is associated with impaired kidney function. Weanling female rats were fed purified diets containing either 0.4 or 0.6% (wt/wt) phosphorus for 28 d. The diet containing 0.6% phosphorus produced marked kidney calcification, as determined both by chemical analysis of kidney calcium and histological examination in kidney sections. Histological examination did not show calcification in stomach, lung, heart or thoracic aorta, which are predisposition sites of metastatic calcification in secondary renal hyperparathyroidism. In rats fed the 0.6% phosphorus diet, phosphorus retention and urinary excretion were greater compared with rats fed the 0.4% phosphorus diet. The following indicators of kidney function were examined: water intake, urinary volume, urine and plasma osmolality, urine and plasma creatinine, urine and plasma urea, urea and creatinine clearance and urinary albumin excretion. Of these indicators, only urinary albumin excretion was significantly increased in rats fed the nephrocalcinogenic diet. In a further experiment, the increase of urinary albumin was reproduced. After pooling the results of the two experiments, in individual rats fed the 0.6% phosphorus diet, the concentration of kidney calcium was found to be positively related with kidney weight expressed relative to body weight (r = 0.82, n = 22) and with albumin excretion in urine (r = 0.79, n = 28). The increased weight of calcinotic kidneys was mainly due to both calcium deposition and tubular hyperplasia. It is concluded that dietary phosphorus-induced nephrocalcinosis is associated with impaired kidney function in rats.

Albumins↗