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PubMed1985

The retention of 59Fe and 65Zn by preruminant lambs given milk-substitutes based on either casein or soya-bean-protein isolate.

Eight newborn lambs were given milk-substitutes based on casein (n 4) or a soya-bean-protein isolate (n 4). On the morning before a 10 d collection period, the milk-substitutes were supplemented with 59Fe as ferric chloride and 65Zn as zinc chloride. Faeces and urine were collected daily and determinations of 59Fe and 65Zn were made on these separately. During a second 10 d period the dosing procedure and collection were repeated but the diet of each lamb was reversed. Mean retention of 59Fe in lambs given the casein diet was 0.50 (SE 0.12) and in those given the soya-bean-protein diet 0.06 (SE 0.05). There were large variations among animals but the treatment effect was significant at P less than 0.05. Retention of 65Zn was significantly greater than that of 59Fe for all lambs but the effect of dietary treatment was similar to that for Fe. 65Zn retention values for casein and soya-bean-protein diets were 0.84 (SE 0.06) and 0.52 (SE 0.03) respectively, and the difference was significant at P less than 0.01. There were only very small amounts of 59Fe and 65Zn in urine, representing 0.002-0.003 of the dose.

Animals↗
PubMed1987

A comparison of the effects of soya-bean protein and casein on bile composition, cholelithiasis and serum lipoprotein lipids in the vervet monkey (Cercopithecus aethiops).

1. Two groups of vervet monkeys (Cercopithecus aethiops) were fed on high-cholesterol diets which differed only with respect to the protein source. In one group casein was the only protein source, while the other group received only soya-bean protein. 2. Samples of blood, bile and liver biopsy material were collected at the commencement of the study and at 3-monthly intervals until termination 12 months later. 3. At the end of the experimental period all the animals (n 19) had high plasma cholesterol levels and had developed pigment gallstones, the compositions and weights of which were not related to the protein source or to plasma cholesterol levels. Gallstone weight was related to the presence of acidic and sulphated mucins in gallbladder mucosa. We were also unable to confirm the hypocholesterolaemic effect of soya-bean protein which has been demonstrated previously in rhesus monkeys and hamsters. Bile composition and plasma lipids did not differ significantly between the casein-fed and soya-bean fed animals. Lithogenic index was below 1 for both groups and did not differ significantly between the two groups. 4. No significant difference was found in the severity of cholelithiasis between the casein-fed and the soya-bean-fed animals.

Animals↗
PubMed1992

Effects of diets containing casein and rapeseed on enzyme secretion from the exocrine pancreas in the pig.

The effect of dietary protein on enzyme activity of pancreatic juice was studied in ten growing, castrated, Large White male pigs. Animals, fitted with permanent cannulas in the pancreatic duct and in the duodenum, were divided into two groups receiving either casein or rapeseed concentrate as a protein source. After a 15 d adaptation period to the experimental diet, the volume of pancreatic secretion was significantly higher, whereas the protein concentration was lower in the casein group compared with the rapeseed group. No statistical difference was observed in the daily protein output between groups. Total secreted activities of carboxypeptidase A (EC 3.4.17.1), and elastase (EC 3.4.21.36) were higher in the casein group during the nocturnal period, whereas total activities of trypsin (EC 3.4.21.4), chymotrypsin (EC 3.4.21.1), carboxypeptidase B (EC 3.4.17.2) and amylase (EC 3.2.1.1) in pancreatic secretions during the post-prandial periods were increased by the ingestion of the rapeseed diet. It is concluded that the pancreatic enzyme secretion is sensitive to the nature of the protein ingested.

Amylases↗
PubMed1997

Cholesterol-lowering effect of policosanol on rabbits with hypercholesterolaemia induced by a wheat starch-casein diet.

The effect of policosanol, a mixture of high-molecular-weight aliphatic alcohols isolated from sugarcane wax, on casein-induced hypercholesterolaemia in rabbits was studied. When policosanol was administered by the oral route once daily for 30 d (50 mg/kg) the increases in plasma total cholesterol and LDL-cholesterol (LDC-C) were significantly reduced when compared with the control group. The incorporation of 3H2O into sterols in the liver was significantly depressed, suggesting inhibition of hepatic cholesterol biosynthesis. The oral administration of policosanol raised the rate of removal of 125I-labelled LDL from serum. Kinetic parameters calculated following injection of [125I]LDL showed than in casein-fed rabbits, the terminal half-life (t1/2) was significantly decreased after policosanol treatment. The hepatic LDL-binding activity was increased after policosanol administration which suggested that the enhanced clearance was due, at least in part, to increased receptor-mediated uptake of LDL by the liver. Considered together, these results suggest that policosanol can significantly reduce the increase of plasma LDL-C in rabbits fed on a wheat starch-casein diet by reducing cholesterol biosynthesis in the liver. Such an effect could account for the enhancement of LDL catabolism through the receptor-mediated pathway.

Animals↗
PubMed2001

The effect of casein phosphopeptides on calcium absorption from calcium-fortified milk in growing rats.

The effect of casein phosphopeptides (CPP) prepared from bovine casein by enzymatic hydrolysis (extrinsic CPP) on Ca absorption from Ca-fortified milk was studied in young male rats, in comparison with that produced from casein in the small intestine (intrinsic CPP). The gastrointestinal Ca disappearance (Ca ingested - (gastric Ca + intestinal Ca )) was calculated as an indirect measurement of Ca absorption. After being fasted overnight, the animals were given 2.0 ml Ca-fortified milk (30 g fat, 35 g protein, 2.7 g Ca/kg) without or with 1.0 mg extrinsic CPP/ml, by gastric intubation. The intestinal soluble Ca level after 15 min and the gastrointestinal Ca disappearance after 15 and 30 min in the rats given Ca-fortified milk with 1.0 mg extrinsic CPP/ml were significantly higher than these figures in the rats given Ca-fortified milk without CPP (P < 0.05). When the rats were given unfortified milk (1.35 g Ca/kg) in another reference experiment, no significant effect on intestinal soluble Ca and gastrointestinal Ca disappearance was apparent from the addition of CPP to milk. Ca availability was estimated by measuring 45Ca-deposits in the bones of rats 48 h after being given 2.0 ml Ca-fortified milk labelled with 45Ca (180 kBq/2 ml) with or without 0.25 mg CPP/ml. The levels of 45Ca radioactivity of the femur and tibia from the rats given Ca-fortified milk with extrinsic CPP were significantly higher than those from the control group (P < 0.05). These results suggest that the addition of CPP to Ca-fortified milk could increase Ca absorption by growing rats mainly from CaCO3 added to the milk. The mechanism of CPP related to the interaction of CPP and Ca in the gastrointestinal tract is discussed.

Animals↗
PubMed2004

Effects of ileo-rectal anastomosis on cholesterol metabolism in pigs fed either casein or extruded soya beans.

The importance of legume proteins in cholesterol metabolism has been recognised, but the hindgut contribution is still unclear. The present work was undertaken to address the role of the caecum-colon in cholesterol metabolism in intact (I) and ileo-rectal anastomosed (IRA) pigs fed with casein or extruded soyabean (ES) diets. Four groups of six growing pigs were assigned to the treatments (casein-I, casein-IRA, ES-I, ES-IRA) for 3 weeks. Plasma total cholesterol, LDL- and HDL-cholesterol were not modified by surgery or diet. In the liver, the ES diet significantly depressed non-esterified, esterified and total cholesterol. The treatments did not affect hepatic 3-hydroxy-3-methylglutaryl CoA reductase, cholesterol 7alpha-hydroxylase or sterol 27-hydroxylase activities. In the gallbladder bile of ES-fed pigs, total cholesterol was depressed while total bile acid concentration was increased. IRA and the ES diet markedly decreased the biliary bile acid microbial metabolites (namely hyodeoxycholic acid) and increased the primary bile acids (mainly hyocholic acid). The concentration of bile hydrophobic acids was decreased only by the ES diet. Faecal neutral sterol output was increased in ES-fed pigs, but the bile acid and the sum of neutral and acidic steroid outputs were not. Microbial transformation of neutral and acidic steroids was markedly reduced by IRA, especially in the ES-fed pigs. Thus, surgery and ES modulated the steroid profile but the caecum-colon did not seem to play a crucial role in determining cholesterolaemia in pigs.

Anastomosis, Surgical↗
PubMed1977

Fractionation by size of casein micelles on controlled-pore glass.

Casein micelles have been separated from skim milk by chromatography on CPG-10 3000 glass beads. Fractionation of the micelles according to size has been demonstrated. Polyacrylamide gel electrophoresis of urea treated micelles reveals that different relative amounts of the major casein components occur in the various micelle fractions. No discernible dissociation of the micelles into monomeric caseins has been observed.

Animals↗
PubMedDate not supplied

Physicochemical characterization and enzymatic degradation of casein microcapsules prepared by aqueous coacervation.

The use of biopolymers in sustained release systems has been studied by many research groups because of the bioavailability and biodegradability of these compounds. Casein is a natural biopolymer whose degradation results in biologically utilisable compounds. The objective of the present study was to assess the potential of casein microcapsules (CAS/MC) as sustained release systems using acetaminophen as a model drug. CAS/MC were prepared by aqueous coacervation in lactate buffer containing gelatin, hydroxypropyl cellulose (HPC) and lecithin. After preparation, the microcapsules were treated, or not, with glutaraldehyde as a cross-linking agent. CAS/MC were loaded using two distinct procedures, either by dissolving 50% of the drug (w/w), relative to casein, in the polymer dispersion or by dissolving the drug in the coacervating solution. The drug present in CAS/MC was quantified by HPLC after an enzymatic degradation assay, and the CAS/MC were analysed by scanning electron microscopy and thermal analysis (differential scanning calorimetry and thermogravimetrical analysis). Loading of the drug was approximately 8% (w/w), with high resistance to enzymatic attack. The absence of an acetaminophen melting peak indicated that there was no drug present on the surface of the cross-linked systems. In addition, loading was accompanied by a reduction of the specific heat capacity of the systems, which suggests a decrease in stability. The outer morphology of the encapsulating polymer was affected by the process of microencapsulation. The data suggest that the microencapsulation process of aqueous coacervation and cross-linking is appropriate for the preparation of microencapsulated systems for sustained drug delivery.

Acetaminophen↗
PubMed1989

Late metabolic acidosis and poor weight gain in moderately pre-term babies fed with a casein-predominant formula: a continuing need for caution.

When our neonatal unit opened in 1984 our formula feeding policy for moderately preterm babies was for casein-predominant rather than "humanized" whey-predominant milk formulae to be given. However, an early cluster of cases of late persistent metabolic acidosis prompted an investigation into the acid-base status and weight gain in preterm infants. This study of 70 healthy, moderately preterm (32-35 weeks) Chinese babies has convincingly shown that a casein-predominant low protein formula is associated with significant metabolic acidosis, persisting sometimes for as long as 8 weeks, and poor weight gain when compared with infants fed on either a humanized or a special low-birthweight formula. This is an important message for the many neonatal units in developing countries where the cost of humanized formulae might initially seem prohibitive, encouraging instead casein-predominant formulae when breast milk is not available. Any additional expense incurred in using humanized formulae will be compensated for by the shortened time spent in hospital.

Acidosis↗
PubMed2004

Effects of 'casoparan', a peptide isolated from casein hydrolysates with mastoparan-like properties.

Casein, a protein found in milk of several species, is divided into different chains from 19 to 25 kDa. Casein is also considered as a source of amino acids and generating peptides with biological activities such as opiate, immunostimulating, antibacterial, peptidase inhibitors, among others. In this work, Sephadex G-10 chromatography followed by high-performance liquid chromatography isolation purified NZCase TT, an industrial culture media for tetanus toxin production. In the first step, four pools were isolated and tested in different assays: isolated smooth muscle assay (guinea pig ileum, rat uterus), phagocytosis in vitro of opsonized sheep red blood cells, and hydrogen peroxide (H2O2) release from mouse peritoneal macrophages. Pool III was the main active pool being able to potentiate bradykinin action in guinea pig ileum, stimulating phagocitic activity by resident macrophages and increasing H2O2 release from macrophages previously activated with bacille Calmette Guérin. Using mass spectra the primary structure of the main peptide from pool III was obtained--INKKI, which corresponds to beta-casein fragment 26-30. The immunostimulating action is probably related to a direct action in macrophage cells.

Animals↗
PubMed2006

Health implications of milk containing beta-casein with the A2 genetic variant.

Milk from dairy cows has long provided a high quality source of protein and selected micronutrients such as calcium to most populations. Recently, a relationship between disease risk and consumption of a specific bovine ss-casein fraction either A1 or A2 genetic variants has been identified. Populations, which consume milk containing high levels of ss-casein A2 variant, have a lower incidence of cardiovascular disease and type 1 diabetes. Furthermore, consumption of milk with the A2 variant may be associated with less severe symptoms of autism and schizophrenia. The mechanism of action focuses on ss-casein A1 and related forms preferentially that are able to produce a bioactive opioid peptide, ss-casomorphin-7 (ss-CM-7) during digestion. Infants may absorb ss-CM-7 due to an immature gastrointestinal tract. Adults, on the other hand, appear to reap the biological activity locally on the intestinal brush boarder. ss-CM-7 can potentially affect numerous opioid receptors in the nervous, endocrine, and immune systems. Whether there is a definite health benefit to milk containing the A2 genetic variant is unknown and requires further investigation.

Adult↗
PubMed1975

[Studies on the protein and amino acid metabolism of laying hens using 15N labeled casein. 4. Fecal excretion of nitrogen and amino acids, digestibility of crude protein and absorption of basic amino acids].

Generally, the faeces of laying hens fed 15N casein rations were found to contain equal proportions of TCE-precipitable and TCE-soluble nitrogen. Considerable variations were observed to occur between the 64 samples investigated (27%-75%) and no explanation was found to account for this fact. The content of basic amino acids in faecal proteins was found to differ considerably from that of the proteins in the intestinal contents. A high lysine content was found after the feeding of wheat. The present trial substantiated this result, provided the casein contained a certain proportion of non-available lysine. The apparent and true digestibility of dietary N was 88% or 91%, that of 15N (2nd and 6th day of experiment) and 92%. During the feeding of labelled casein a higher level of N labelling was found in the TCE-soluble portion of the faeces, whereas on the 8th to 12th day a higher level of labelling was observed in the TCE-precipitable portion of the faeces. The peak of 15N excretion occurred on the 3rd day of experiment. When 15N administration terminated the atom% 15N in the faeces and in urine was found to decrease rapidly approximating the initial level of labelling asymptotically.

Amino Acids↗
PubMed1977

[Energy requirements for the synthesis of body proteins during growth as determined in model experiments in rats. 2. Studies with dietary casein and wheat gluten used unsupplemented or supplemented with methionine or lysine].

Rats were used in 7 trials each comprising 9 animals (197 total metabolism trials carried out at an environmental temperature of 30 degree). The animals received casein, casein+methionine, wheat gluten, wheat gluten+lysine as protein sources and were investigated for their nitrogen and energy turnover. The rations fed contained between 10% and 27% protein. Supplementation of the natural proteins with synthetic amino acids positively influenced the growth rate and the rate of N retention. The feeding of wheat gluten as sole protein source induced an absolute depression of the food and energy intake. The rates of tetention of protein and fat energy per animal/day showed opposing trends, in dependence upon the protein levels in the rations. It was found in the trials with casein that the proteins yielded 25%, or 18% of the total energy retention if the rats received low protein rations while the percentage of protein energy retention increased to 49-53%, if the rations contained high protein levels. The rats utilized between 67% and 84% of the metabolizable energy for the turnover of body energy. A negative correlation was found between the levels of energy utilization and protein intake. The energy demends for protein retention were calculated (mean of all trials) to be 1.67 kcal of metabolizable energy while those for fat retention amounted to 1.15 kcal. The energy demands for protein retention were not found to be dependent on the type of protein source used. The maintenance requirements of the rats were 102 kcal of metabolizable energy per kg LM0,75.

Animal Feed↗
PubMed1982

Studies with rainbow trout (Salmo gairdneri, R.) on the optimum level of dietary protein and on the utilization of casein.

Two feeding trials with rainbow trout were conducted over 100 days. Replacement of krill meal by gelatinized maize starch had negative effects on feed conversion and growth only when dietary protein was reduced below 33 per cent of the dry matter. When casein was the only source of protein, poor conversion and growth rates resulted. In diets containing 30 per cent krill meal, however, replacing 200 g per kg of gelatinized maize starch by casein improved feed conversion and growth. Increasing dietary gelatinized maize starch correspondingly increased glycogen contents of the liver. Replacing krill protein by casein caused fatty livers.

Animals↗
PubMed1999

Whole body protein turnover of growing rats in response to different dietary proteins--soy protein or casein.

Whole body protein turnover was studied in growing rats fed restrictively on isoenergetic (GE 17.6 MJ/kg DM) and isonitrogenous (104 g CP/kg DM) diets based on soy protein isolate or casein supplemented with D,L-methionine. During each of the three separate experiments six male Fischer rats per group were housed individually in metabolic cages at 24 degrees C. Prefeeding of both dietary groups up to similar body weights at the start of the main experimental periods (105-134 g) lasted up to 16 d for casein-fed rats and up to 30 d for the soy protein-fed rats. Following the energy and nitrogen balance periods whole-body protein synthesis was estimated by the end-product method using a single tracer dose of a mixture of 15N-labelled amino acids. Fractional protein accretion rate [% of the protein pool accreted per day] was significantly lower in soy protein-rats than in casein-fed rats in all three experiments whereas fractional synthesis rate was not significantly lower. Therefore, protein breakdown subsequently calculated as the difference between synthesis and accretion showed a tendency towards higher values in this group. In soy protein-fed rats also a tendency towards higher excretion of 3-methylhistidine as a marker of myofibrillar protein breakdown was observed. It is concluded that increase in lean tissue growth resulting from improved protein quality is brought about by changes of both rates, by small increase of protein synthesis and by reduced rate of body protein breakdown.

Animals↗
PubMed1990

Monoclonal antibodies against nuclear casein kinase NII (PK-N2).

A monoclonal antibody was produced against the nuclear casein kinase II (PK-N2) isolated from rat liver. The antibody was of the IgM class, and showed immunoreactivity towards the higher molecular weight subunit (41K Da) of the protein kinase in Western blots. The antibody was equally reactive towards the PK-N2 isolated from rat ventral prostate indicating that it can recognize the enzyme from different tissues of the rat. The antibody also detected the cytosolic casein kinase II (CK-2) suggesting significant similarity of the antigenic domains in the two forms of this protein kinase. No binding was detected with the nuclear or cytosolic casein kinase I (PK-N1 and CK-1). The antibody did not inhibit the enzyme activity or directly precipitate the enzyme, but when coupled to an affinity matrix and cross-linked with dimethylpimelimidate, it was capable of removing nearly all the PK-N2 activity from solution.

Animals↗
PubMed2005

Effect of casein hydrolysate, prepared with protease derived from Aspergillus oryzae, on subjects with high-normal blood pressure or mild hypertension.

Casein hydrolysate, prepared with Aspergillus oryzae protease, contains angiotensin I-converting enzyme inhibitory peptides, such as Val-Pro-Pro and Ile-Pro-Pro. We conducted a randomized, double-blind, placebo-controlled study to evaluate the effect of casein hydrolysate on the blood pressure of 144 subjects with high-normal blood pressure (n = 104) and mild hypertension (n = 40). Subjects were randomly assigned to two groups for a 12-week intake period. In the test group, both systolic (SBP) and diastolic (DBP) blood pressure decreased significantly compared with the placebo group: SBP/DBP significantly decreased from 138.2 +/- 6.5/84.4 +/- 5.3 mm Hg at week 0 to 132.3 +/- 7.3 (P < .001)/81.2 +/- 4.8 mm Hg (P < .001) at week 12. In the stratified analysis, the test product showed an antihypertensive effect in both the subject group with high-normal blood pressure and that with mild hypertension. No side effect was observed in any subjects in this study. These results demonstrate that the casein hydrolysate, prepared with A. oryzae protease, produced a significant reduction in blood pressure in a population of subjects with high-normal blood pressure or mild hypertension without an adverse event.

Adult↗
PubMed1979

Isolation of a glycopolypeptide fraction with Lactobacillus bifidus subspecies pennsylvanicus growth-promoting activity from whole human milk casein.

Human milk casein samples were digested with trypsin and chymotrypsin, and a glycopolypeptide fraction was isolated from the soluble portion of the digests by a series of gel filtration steps. The glycopeptide fraction stimulated the growth of Lactobacillus bifidus subspecies pennsylvanicius to the same extent as a whey glycopolypeptide fraction previously isolated (Pediat. Res. 10: 1, 1976). It contained between 60 and 70% carbohydrate consisting of galactose, galactosamine, glucosamine, fucose, and sialic acid. This, along with its apparent molecular weight of near 30,000 was also similar to the respective parameters of the whey glycopolypeptide. It is proposed that human milk casein may serve a dual function: that serving the nutritional needs of the breast-fed infant, and that stimulating the growth of L. bifidus subspecies pennsylvanicus. Additionally, the whey glycopolypeptide may arise from casein through proteolysis by an endogenous milk protease.

Actinomycetaceae↗