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Biomedical subjects

A C Beynen

Publications and source records attributed to A C Beynen.

At least 163 records · Page 9Linked to original sources
PubMed1996

Boiled coffee fails to raise serum cholesterol in hamsters and rats.

Boiled coffee contains the lipid compounds cafestol and kahweol, which raise cholesterol strongly in man. These lipids are retained by paper filters. In a search for an animal model for the effect of coffee lipids on serum cholesterol concentrations, we fed hamsters (Mesocricetus auratus) and rats on mash diets consisting of a purified base diet and either boiled water, unfiltered boiled coffee or filtered boiled coffee. After a feeding period of 8 weeks there was no statistically significant effect of unfiltered boiled coffee on serum total cholesterol and triacylglycerol concentrations in either the hamsters or the rats. The level of serum cholesterol did respond predictably to the addition of cholesterol and/or saturated fatty acids to the diet. The lack of effect of unfiltered boiled coffee in the hamsters and the rats, when compared with the previously reported activity in humans, could not be explained by dosage, duration of treatment, mode of administration or by insufficient statistical power. It is concluded that hamsters and rats are insensitive to unfiltered boiled coffee and thus are unsuitable models for investigating its hypercholesterolaemic effect.

Animals↗
PubMed1996

Copper homeostasis in rats fed on a high-sulphide diet.

The mechanism underlying the reduced Cu status in rats fed on a high-sulphide diet was investigated. Male rats aged 6 weeks were fed ad libitum on purified diets containing either 0 or 500 mg S2-/kg and demineralized water for a period of 2 weeks. The high-sulphide diet had no effect on feed intake, body-weight gain or weight of liver and kidney but significantly reduced Cu concentrations in plasma and kidney. Biliary Cu excretion was decreased significantly in rats fed on the high-sulphide diet. Apparent Cu absorption (Cu intake-faecal Cu) and true Cu absorption (Cu intake-(faecal Cu-biliary Cu)) were significantly lowered after sulphide feeding for 2 weeks. Rats fed on the high-sulphide diet excreted less Cu in urine than did the controls. We conclude that high sulphide intake reduces Cu status in rats through inhibition of Cu absorption which is reflected by a decrease in biliary Cu excretion as a secondary feature.

Animals↗
PubMed1996

Mechanism underlying the inhibitory effect of high calcium carbonate intake on iron bioavailability from ferrous sulphate in anaemic rats.

The influence of high CaCO3 intake on the bioavailability of Fe from FeSO4 was assessed during Fe repletion of rats with Fe-deficiency-induced anaemia. Fe-deficient rats with a mean blood haemoglobin concentration of 4.1 mmol/l were fed on purified Fe-adequate diets containing either 6.2 or 25.0 g CaCO3/kg (ten rats per group). Haemoglobin repletion after 14 d was significantly depressed by high CaCO3 intake (9.5 v. 9.8 mmol/l for high and low CaCO3 intake respectively; P = 0.03), as was apparent Fe retention (367 v. 552 micrograms/d during days 5-7, P < 0.001; 146 v. 196 micrograms/d during days 19-21, P < 0.001). The concentration of Fe in the liquid phase of the proximal half of the small intestine was significantly lower in the high-CaCO3 group (3.71 v. 5.20 micrograms/g digesta; P = 0.02). Mucosal uptake and mucosal transfer of Fe were determined with orally administered 59Fe and Cr as a non-absorbable marker. Mucosal transfer was significantly diminished by CaCO3 loading (90 v. 100% of mucosal uptake; P = 0.04), whereas mucosal uptake was not. 59Fe retention values at 14 d after administration were not significantly different (57.6 v. 51.9%; P = 0.14). Fe contents of liver and spleen were significantly decreased by high compared with low CaCO3 intake (879 v. 590 micrograms Fe in liver, P < 0.001; 92 v. 63 micrograms Fe in spleen, P < 0.001). It is concluded that high intake of CaCO3 depresses Fe bioavailability in rats. The CaCO3-induced decrease in Fe solubility in the digesta probably was associated with an increased efficiency of mucosal Fe uptake so that the amount of mucosal uptake remained unaltered. The CaCO3-induced decrease in Fe transfer through the mucosal cytoplasm and/or basolateral membrane may have been responsible for the concurrent decrease in Fe bioavailability.

Anemia, Iron-Deficiency↗
PubMed1996

Supplemental vitamin A enhances the recovery from iron deficiency in rats with chronic vitamin A deficiency.

Studies with anaemic children and pregnant women from areas where vitamin A deficiency is endemic have shown a beneficial effect on Fe status of supplemental vitamin A in addition to Fe supplementation. This suggests a relationship between vitamin A and Fe status, which we attempted to mimic in rats with anaemia and chronic vitamin A deficiency. Male rats were fed on Fe-adequate diets (35 mg Fe/kg) containing different levels of vitamin A (1200, 450, 150, 75 and 0 retinol equivalent (RE)/kg feed) until they were 5 weeks old. These diets were identical to the diets fed to their mothers. Then the young male rats were transferred to diets containing the same levels of vitamin A but no added Fe. After another 2 weeks the rats were repleted with Fe (35 mg/kg feed) without or with vitamin A to a level of 1200 RE/kg feed. Increased vitamin A intake by the groups previously fed on diets with either 0 or 75 RE/kg produced a reduction in blood haemoglobin concentration, packed cell volume and erythrocyte count. In the group which had been fed on the diet without vitamin A, supplemental vitamin A raised mean cell volume, plasma Fe concentration and total Fe-binding capacity. Vitamin A supplementation during the period of Fe repletion produced a decrease in splenic and tibia Fe concentration, the effect being greater with increasing severity of previous vitamin A deficiency. The paradoxical effect of supplemental vitamin A on haemoglobin, packed cell volume and erythrocyte count can be explained by a decrease in the degree of haemoconcentration. Thus, the positive effect of supplemental vitamin A seen in humans is also observed with rats under controlled experimental conditions. We speculate that supplemental vitamin A during Fe repletion contributes to optimum erythropoiesis and Fe mobilization when baseline vitamin A status is impaired.

Anemia, Iron-Deficiency↗
PubMed1996

Neither raw nor retrograded resistant starch lowers fasting serum cholesterol concentrations in healthy normolipidemic subjects.

The question addressed was whether dietary resistant starch would lower serum cholesterol and triacylglycerol concentrations in healthy normolipidemic subjects. In a randomized single-blind 3 x 3 Latin-square study with corrections for any carryover effects, 27 males and 30 females consumed supplements containing glucose or resistant starch (RS) from raw high-amylose cornstarch (RS2) or from retrograded high-amylose cornstarch (RS3). The RS2 and RS3 supplements provided 30 g RS/d. Each type of supplement was consumed in addition to the habitual diet for 3 wk. At the end of each 3-wk period, fasting blood samples and a 24-h food-consumption recall were obtained from each subject. The subjects collected 24-h urine samples for lithium determination, which was added to the supplements to check compliance. Mean lithium recovery was 97% and did not differ between supplements. The mean composition of the background diet was similar when the three supplements were taken. Body weight remained constant throughout the study. There were no significant differences in the fasting concentrations of serum total, high-density-lipoprotein (HDL), and low-density-lipoprotein (LDL) cholesterol; triacylglycerols, or 3 alpha-hydroxy bile acids after consumption of glucose, RS2, or RS3. Evidence is presented that the lack of effect of RS2 and RS3 on serum lipid concentrations cannot be explained by insufficient statistical power, a low dose, or a short duration of treatment. The subjects reported softer stools and more gastrointestinal symptoms after supplementation with RS than after glucose. Neither the RS2 nor the RS3 supplements lowered serum lipid concentrations in healthy, normolipidemic men and women.

Adolescent↗
PubMed1996

Higher postpartum hepatic triacylglycerol concentrations in dairy cows with free rather than restricted access to feed during the dry period are associated with lower activities of hepatic glycerolphosphate acyltransferase.

We investigated the activities of hepatic glycerolipid synthesizing enzymes during postpartum fatty liver development in 10 high-producing dairy cows that had free access to feed during the dry period; a parallel group of 8 control cows was fed according to recommended energy requirements. After calving, both test and control cows had free access to feed. In the period of 10-14 wk before calving, voluntary dry matter intake of the test cows was 20.6 kg/d (SEM 0.42); the restricted control cows received 7 kg/d. Postpartum triacylglycerol concentrations in liver biopsies were one- to twofold higher in the test than in the control cows. The higher plasma nonesterified fatty acid (NEFA) concentrations after parturition in the test vs. the control group were probably caused by a more negative energy balance in the test cows, which was associated with a slightly lower postpartum dry matter intake. After calving, hepatic mitochondrial glycerolphosphate acyltransferase (GPAT) activities were significantly lower in the test than in the restricted control cows. A low GPAT activity may divert fatty acids from esterification to beta-oxidation to protect the hepatocytes against further accumulation of triacylglycerols. The activities of hepatic phosphatidate phosphohydrolase, diacylglycerol acyltransferase, and cholinephosphate cytidylyltransferase were not different in the two groups. This study indicates that in cows given free instead of restricted access to feed during the dry period have a postpartum hepatic triacylglycerol accumulation that is mainly determined by a raised hepatic uptake of plasma NEFA.

Alkaline Phosphatase↗
PubMed1996

Dietary raw versus retrograded resistant starch enhances apparent but not true magnesium absorption in rats.

Dietary raw (RS2) vs. retrograded resistant starch (RS3) raises apparent magnesium absorption in rats. The mechanism proposed is that RS2 enhances magnesium avaibility for absorption; it does this by increasing ileal solubility of magnesium due to a reduction in pH as a consequence of RS2 fermentation in the gut. The mechanism implies that dietary RS2 vs. RS3 would raise true magnesium absorption and stimulate reabsorption of endogenous magnesium, leading to a lower fecal excretion of endogenous magnesium. Dietary lactulose vs. glucose raises apparent magnesium absorption, and the mechanism proposed is similar to that for the stimulatory effect of RS2 vs. RS3. Thus, we measured in rats fed RS3, RS2, glucose or lactulose true magnesium absorption on the basis of the retention of the orally and intraperitoneally administered radiotracer 28Mg. Feeding rats RS2 instead of RS3 significantly enhanced apparent but not true magnesium absorption, because RS2 lowered fecal excretion of endogenous magnesium. When compared with dietary glucose, lactulose significantly raised both apparent and true magnesium absorption, but did not affect fecal excretion of endogenous magnesium. It is suggested that the proposed mechanism by which RS2 and lactulose would enhance magnesium absorption is disproved by the present data.

Absorption↗
PubMed1996

Preferences of mice and rats for types of bedding material.

The type of bedding material has been reported to affect the environment in both the animal cage and animal room. It has an impact on the health and well-being of the animals and may cause biased experimental results. Requirements for bedding materials, particularly those regarding animal comfort are poorly supported by experimental data. In this study, various types of bedding material were evaluated using preference tests with mice and rats. It was found that beddings consisting of relatively small particles (< or = 1.2 x 1.6 mm2) were generally avoided, whereas beddings consisting of large fibrous particles were preferred. The characteristics of the bedding materials were further investigated by scanning the size and shape of the particles, and by the assessment of ultrasound produced by the moving of the beddings. The results seem to indicate that size manipulability are among the main determinants of the appreciation of bedding particles by laboratory mice and rats, and larger particles are preferred.

Animal Husbandry↗
PubMed1995

Copper metabolism in analbuminaemic rats fed a high-copper diet.

Copper metabolism in male Nagase analbuminaemic (NA) rats was compared with that in male Sprague Dawley (SD) rats fed purified diets containing either 5 or 100 mg Cu/kg diet. Dietary copper loading increased hepatic and kidney copper concentrations in both strains to the same extent, but baseline values were higher in the NA rats. There was no strain difference in true and apparent copper absorption nor in faecal endogenous and urinary copper excretion. NA rats had higher levels of radioactivity in kidneys at 2 hr after intraperitoneal administration of 64Cu. As based on the distribution of added 64Cu, about 70% of plasma copper appeared to be in the non-protein compartment in the NA rats, whereas in SD rats, it was only about 1%. It is concluded that the NA rats are able to maintain a relatively normal metabolism of copper, even after dietary copper challenge. In the NA rats, zinc concentrations in kidneys, liver and urinary zinc excretion were elevated when compared with SD rats. The high-copper diet did not affect tissue zinc concentrations and apparent zinc absorption in both strains of rats.

Administration, Oral↗
PubMed1995

Iron and copper metabolism in analbuminaemic rats fed a high-iron diet.

The metabolism of iron and copper in male Nagase analbuminaemic (NA) and Sprague Dawley (SD) rats was compared. Relative liver weight was higher and spleen weight significantly lower in NA than SD rats. In NA rats, red blood cell count, haemoglobin and haematocrit were lower, whereas plasma transferrin, total iron-binding capacity and mean corpuscular haemoglobin were higher when compared with SD rats. Iron concentrations in plasma, liver, kidneys and heart were higher, and those in the spleen and tibia were lower, in NA rats. The iron concentrations in liver and spleen were positively correlated with the amount of brown pigment as observed histopathologically. Bile flow as well as biliary iron and copper excretion were higher in NA than SD rats. Copper concentrations in liver, kidneys and plasma were higher in NA rats. Plasma levels of ceruloplasmin were about two-fold higher in NA rats. The feeding of a high-iron diet reduced kidney copper concentrations in both strains of rats, which was associated with a decrease in the absorption and biliary excretion of copper.

Animals↗
PubMed1995

Replacement of digestible by resistant starch lowers diet-induced thermogenesis in healthy men.

The present study describes the effect of replacement of digestible starch by resistant starch (RS) on diet-induced thermogenesis (DIT), postprandial glucose and insulin responses, and colonic fermentation. Ten healthy males consumed three test meals, consisting of diluted, artificially-sweetened fruit syrup and either 50 g raw potato starch (550 g RS/kg), or 50 g pregelatinized potato starch (0 g RS/kg) or 30 g pregelatinized potato starch plus 20 g lactulose (670 g indigestible disaccharide/kg). The meals were served in the morning after an overnight fast. Each volunteer consumed each meal twice on six separate days in random order. Metabolic rate was measured by indirect calorimetry in the fasting state for 15 min and postprandially for 5 h. Shortly before and hourly up to 7 h after consumption of the test meal, end-expiratory breath samples were obtained for H2 and CH4 analysis. Shortly before the meal and 30, 60, 180, and 300 min postprandially, blood samples were taken for glucose and insulin analyses. Postprandial increases in glucose and insulin levels were proportional to the amount of digestible carbohydrate in the meal. Breath H2 and CH4 concentrations indicated that the pregelatinized starch was not fermented and that lactulose was fermented rapidly. Fermentation of the raw starch started only 6 to 7 h after consumption, resulting in a rise in breath H2 but not in CH4. The replacement of 27 g digestible starch by RS in a single meal lowered DIT by on average 90 kJ/5 h, as could also be calculated by assuming that RS does not contribute to DIT. The ingestion of lactulose resulted in a substantial rise in DIT which was most probably caused by its fermentation.

Adult↗
PubMed1995

High tin intake reduces copper status in rats through inhibition of copper absorption.

The mechanism underlying the reduced Cu status in rats fed on a high-Sn diet was investigated. Male rats aged 4 weeks were fed ad lib. on purified diets containing either 1 or 100 mg Sn/kg and demineralized water for a period of 4 weeks. The high-Sn diet had no effect on feed intake, body-weight gain or weight of liver and kidney but significantly reduced Cu concentrations in plasma, liver and kidney. Biliary Cu excretion was decreased significantly in rats fed on the high-Sn diet. Apparent Cu absorption (Cu intake-faecal Cu) was not affected by the high-Sn diet, but the estimate of true Cu absorption (Cu intake-(faecal Cu-biliary Cu)) was significantly reduced. We conclude that high Sn intake reduces Cu status in rats through inhibition of Cu absorption. The decreased biliary Cu excretion observed on the high-Sn diet is a result of the reduced Cu absorption.

Animals↗
PubMed1995

Effect of dietary magnesium level on urinary and faecal excretion of calcium, magnesium and phosphorus in adult, ovariectomized cats.

Dietary Mg restriction is generally considered to contribute to the prevention of struvite urolithiasis in cats, but its effects on faecal and urinary excretion of Ca and P have not been systematically investigated. The present study seeks to fill the gap. In a 4 x 4-week crossover study, ovariectomized cats were fed on purified diets containing either 0.40, 0.79, 1.59 or 3.17 mmol Mg/MJ (0.19, 0.38, 0.76 and 1.52 g Mg/kg diet). Increasing the dietary Mg level from 0.40 to 3.17 mmol Mg/MJ by the addition of extra MgCO3 raised urinary and faecal excretion of Mg from 0.14 to 0.68 mmol/MJ and from 0.28 to 1.66 mmol/MJ respectively. The 8-fold increase in Mg intake significantly raised urinary excretion of Ca from 0.06 to 0.09 mmol/MJ. Apparent absorption and urinary excretion of P were depressed by 13 and 25% respectively when the dietary Mg level was raised from 0.40 to 3.17 mmol/MJ. A dietary level of 0.40 mmol Mg/MJ (0.19 g Mg/kg diet) was found to be sufficient to maintain Mg balance in the adult ovariectomized cats fed on the purified diet.

Animals↗
PubMed1995

Dietary phosphorus restriction to half the minimum required amount slightly reduces weight gain and length of tibia, but sustains femur mineralization and prevents nephrocalcinosis in female kittens.

The effects of dietary P restriction to half the recommended minimum level on growth, bone and renal mineralization and urinary composition were studied in female kittens. In two separate experiments, 8-week-old weanling kittens were fed on purified diets containing either 4.6 or 9.2 mmol P/MJ (2.8 or 5.6 g P/kg diet). In the second experiment there was an additional low-P diet in which the Ca concentration was reduced from 9.5 to 4.8 mmol/MJ (7.5 v. 3.8 g Ca/kg diet). P restriction slightly but systematically reduced weight gain (to a maximum of 16%) and growth of the tibia (by 1-4%); the former effect was statistically significant (P < 0.05) between the ages of 15 and 20 weeks in Expt 1 only, and the latter did not reach statistical significance at any time point (P > or = 0.13). No adverse effect of P restriction was found on mineralization of femur at the age of 39 weeks. Kidney Ca concentrations were significantly lowered (Expt 1, 6 v. 20 mumol/g dry weight, P < 0.001; Expt 2, 7 v. 16 mumol/g dry weight, P < 0.01) in cats fed on the low-P diets, this effect not being affected by the dietary Ca:P ratio. Urinary P concentration was significantly depressed (by 50-96%) after feeding the low-P diets (P < 0.001). P intake did not influence P, Ca and Mg retention during the period of 15 to 39 weeks of age.

Animals↗
PubMed1995

Evaluation of a two-generation rat model for vitamin A deficiency and the interrelationship with iron metabolism.

In order to induce a range of vitamin A-deficient states in young growing rats and to study the effect of vitamin A deficiency on Fe status, we designed the following two-generation experiment. Dams were fed on diets with one of five vitamin A levels from 2 weeks before and throughout pregnancy and lactation. The pups received the same diets as their mothers both before and after weaning. The five dietary levels of vitamin A were 1200, 450, 150, 75 and 0 retinol equivalents/kg feed. Vitamin A intake did not affect reproduction outcome, nor were body and liver weights of the pups affected when they were 3.5 weeks old. Male pups with normal vitamin A status had higher plasma retinol levels than female pups. Vitamin A status of the offspring was affected from 3.5 weeks onwards. Body and liver weights were decreased in the male pups given the lowest dietary vitamin A levels from week 6.5 onwards but not in the female pups. Fe status was marginally affected. Haemoglobin levels were increased and total Fe-binding capacity was decreased in the groups given no dietary vitamin A at week 9.5. Splenic Fe was increased only in the male pups given the lowest levels of dietary vitamin A. However, as a whole, Fe status was only mildly affected and subject to considerable variation. We conclude that the two-generation rat model described here is not suitable for studying effects of vitamin A deficiency on Fe metabolism.

Animals↗
PubMed1995

High iron intake depresses hepatic copper content in goats.

Earlier studies with ruminants point to a depressant effect of dietary iron on the copper status. To verify this we determined hepatic copper concentrations in dry, non-pregnant goats subjected to a 56 x 56-days cross-over trial with adequate copper rations containing either 269 or 2380 mg iron/kg dry matter. High iron intake reduced the group mean plasma copper (by 18%) and caeruloplasmin activity (by 13%) and produced a significant decrease (27%) in hepatic copper concentrations. Hepatic iron concentrations were raised (by 56%) after feeding the high iron ration. It is concluded that high dietary levels of iron, within the range of their fluctuation in silage and forage, can impair the copper status of ruminants, especially when concurrent intakes of copper are low.

Animals↗
PubMed1995

Liver triacylglycerol concentrations around parturition in goats with either pre-partum restricted or free access to feed.

The hypothesis was tested that goats allowed ad libitum access to feed during the dry period develop higher post partum hepatic triacylglycerol concentrations than do goats given a restricted amount of feed during the dry period. Goats in their second or more pregnancies were either given a restricted amount of hay, maize silage and concentrate (n = 5) or had free access to this feed mixture while the composition was kept constant (n = 11). After parturition both groups were allowed ad libitum access to feed. Post partum liver triacylglycerol concentrations, as measured in liver biopsies, were significantly raised in goats allowed ad libitum access to feed during the dry period. The increase in liver triacylglycerols was associated with slightly higher plasma concentrations of non-esterified fatty acids but lower serum 3-hydroxybutyrate concentrations. The feeding regimen during the dry period did not significantly influence post partum liver glycogen concentrations and serum levels of glucose, cholesterol, and insulin. The increase in post partum liver triacylglycerol concentrations in the goats allowed ad libitum access to feed instead of a restricted ration during the dry period, was associated with a significant rise in serum alkaline phosphatase activities, whereas other liver function and cell damage indicators in serum, i.e. aspartate aminotransferase, lactate dehydrogenase, gamma glutamyl transpeptidase, and bilirubin, were unchanged. Feed intake after parturition tended to be higher in the goats allowed ad libitum access to feed during the dry period but milk production was significantly raised.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗