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At least 19 recordsLinked to original sources
PubMed1977

Blood antigen, serum protein, and milk protein gene frequencies and genetic interrelationships in Holstein cattle.

Gene frequencies at ten blood group loci, one serum protein locus, and four milk protein loci were determined for the Holstein-Friesian breed in the United States. The sample consisted of 8630 cows in 51 herds from 10 states. Because of the close linkage among casein subloci and the concimitant rarity of crossover-recombinant groups, casein gene combination or haplotype frequencies were determined also. As one means of comparison of systems, indices of homozygosity and number of effective alleles were calculated. These indices were proposed also to be useful tools for monitoring changes in genetic variability of breeds. Genotypes within codominant systems and phenotypes associated with paired-system combinations generally were not randomly occurring. Paired system phenotypes within the sire sample corresponded much more closely to expectations of randomness.

Alleles↗
PubMed1976

Effect of psychrotrophic bacteria from raw milk on milk proteins and stability of milk proteins to ultrahigh temperature treatment.

The effects of psychrotroph growth in raw milk on proteins of mils and on the response of milk proteins to heat treatments with ultrahigh temperature were studied. Ten gram-negative psychrotrophs isolated from raw milk readily attacked raw milk proteins. Kappa- and beta-casein were most susceptible although some of the isolates also attacked the whey proteins. Detectable proteolysis did not require large psychrotroph populations. A 10 to 20% decrease in kappa-casein during 2 days at 5 C accompanied growth of one isolate to a population of only 10,000/ml. Growth of psychrotrophs in raw milk predisposed the proteins to deleterious effects of ultrahigh temperature treatments. Ultrahigh temperature treatment by direct steam injection had little effect on raw milk caseins and decreased alpha-lactalbumin and beta-lactoglobulin by 21% and 34%, respectively. Milk that had undergone proteolysis exhibited decreased detectable kappa-, beta-, and alphas-caseins and increased loss of beta-lactoglobulin as a result of ultrahigh temperature treatment. Milk suffering extensive kappa-casein degradation coagulated during ultrahigh temperature treatment. Coagulation during or shortly after heating increased with severity of heat treatment and size of psychrotroph population.

Animals↗
PubMed1977

Secretory IgA antibodies against cow's milk proteins in human milk and their possible effect in mixed feeding.

Antibodies of the secretory IgA type against cow's milk proteins were consistently found in human milk. With the assumption that such antibodies can help to prevent or at least diminish the contact between native cow's milk proteins and the lymphoid system of babies on mixed feeding, the levels of antibodies of various immunoglobulin classes against bovine milk proteins were measured in different groups of babies. Those on artificial feeds who had been on mixed feeding of human milk and cow's milk for less than 1 week had significantly higher levels of IgG antibodies to cow's milk proteins than those who had been on mixed feeding for a period longer than 3 weeks.

Antigens↗
PubMed1979

[Milk proteins for food. I. Some aspects of the use of milk proteins for the protein supply to the population of the GDR].

Milk protein accounts for approximately 21% of the protein supply to the population in the GDR. All milk protein fractions have a high nutritional-physiological value and favourable functional properties. This notwithstanding, only 50% of the milk protein processed by the dairy industry are at present employed in human nutrition, the remainder is used as a provender. The reasons for this situation are discussed. Principles of procedures for the industrial production of milk protein concentrates are presented.

Amino Acids↗
PubMed1979

Comparative aspects of milk proteins.

The current status of knowledge of the major proteins of milks of various species is evaluated. Most of the non-bovine milk proteins are homologous with the recognized families of those of Bos taurus, alpha S1-caseins, alpha S2-caseins, beta-caseins, kappa-caseins, beta-lactoglobulins, and alpha-lactalbumins, each family representing a separate genetic locus specific to the mammary gland. No prominent milk protein not homologous to one of these families has yet been discovered in milk of any species. Genetic polymorphism resulting from substitutions in the polypeptide chains and various degrees of post-translational phosphorylation, glycosylation, and proteolysis have been identified in milk proteins of several species. Total protein production ranges among species from about 0.5 to 10 g/d per kg0.75 maternal weight. Proportions of the several proteins vary greatly among species, but few accurate analytical data are available except for total casein and total whey protein contents.

Amino Acids↗
PubMed1977

Heat induced crosslinks in milk proteins and consequences for the milk system.

The protein system of milk is rather unusual, there are nearly no interchain crosslinks found. Even intrachain crosslinks, especially disulfide bridges, are present only in about every fourth protein molecule. Heating causes dramatic changes in the structure of milk proteins, resulting in the formation of polymeric networks. The contribution of individual milk proteins, namely the beta-lactoglobulins, alpha-lactalbumin and chi-casein, to the formation of crosslinks is studied with respect to heating temperature and time, pH and atmosphere. Measured are changes in molecular weights and in the SH/SS-levels as well as the formation of dehydroalanine, lysinoalanine, lanthionine and isopeptide bonds. Some practical aspects of crosslinking in milk proteins are discussed.

Animals↗
PubMedDate not supplied

Milk proteins and mammary cancer: a review.

Milk proteins are of potential value in characterizing mammary carcinoma from a functional point of view. The major milk proteins are described with special reference to human milk. The caseins, whey proteins and membrane structures in the milk are discussed in terms of their chemical, biological and immunological properties. In vitro culture systems help to define the hormone dependency of normal mammary tissues and mammary carcinomas. The control of proliferation and milk protein production are partially independent, and this becomes especially evident in experimental tumours. Clinical samples of human tumours and plasma from patients with mammary carcinoma show differences in the level of certain milk proteins. These appear to relate to tumour spread, state of differentiation and the presence of hormone receptors.

Animals↗
PubMedDate not supplied

Balanced intraintestinal nutrition: digestion, absorption and biological value of selected preparations of milk proteins.

The absorption of an enzymatic hydrolysate of whey proteins, hydrolysates of milk proteins and casein, 7% hydrolysate of bovine blood produced by Polfa under the trade name "Aminokwasy", and a standard mixture of amino acids from isolated small intestine loop of dogs and rats was compared. The composition of amino acids of the initial proteins and hydrolysates obtained from these proteins was determined. The biological value of selected proteins and hydrolysates was assessed determining the mean weight gain, nitrogen content of the body, urinary excretion of urea and creatinine, blood urea level and NPU. No significant differences were found in the absorption of nitrogen from the hydrolysate of milk and whey proteins. The nutritional value of whey protein hydrolysate was, however, slightly higher than that of an analogous hydrolysate of milk proteins. It seems that of all tested proteins whey hydrolysate (free of lactose) is the most suitable source for obtaining preparations for no-residue intraintestinal feeding.

Amino Acids↗
PubMed1978

Specific antibodies in infants with gastrointestinal intolerance to cow's milk protein.

Antibodies of various immunoglobulin classes against cow's milk proteins were studied in infants and children with cow's milk protein intolerance, gluten-sensitive enteropathy and acute gastroenteritis. Their IgE, IgG, IgM and IgA antibody levels determined with the enzyme-linked immunosorbent assay (ELISA) and the IgE antibodies also determined with RAST, were compared with reference groups of children and adults. IgE, IgT or IgA antibodies against unseparated cow's milk proteins, alpha-lactalbumin, beta-lactoglobulin, alpha-casein and beta-casein were present in many of the studied samples, but did not discriminate between the individuals with and without intolerance symptoms. As a group, the infants with late reactions to cow's milk showed increased levels of IgE and IgG antibodies detected with the ELISA, while patients with gluten-sensitive enteropathy had significantly increased levels of IgG and IgA antibodies of cow's milk proteins compared to the reference group. By combining the findings of antibody increases in various immunoglobulin classes, an individual discrimination could be reached. Thus, 8 of 9 of the patients with late reactions to cow's milk had increased levels of IgE or IgG + IgA antibodies as compared to 3 of 22 in the reference group. Serodiagnosis with the ELISA may, therefore, be of some use in patients with a suspicion of cow's milk protein intolerance.

Animals↗
PubMed1976

[On the occurence of isopeptide bonds in heated milk protein (author's transl)].

Milk, milk products and individual milk proteins were subjected to different heat treatments either as powders or in aquous systems. After complete hydrolysis of the peptide bonds (alpha-amide bonds) by a system of four proteinases or peptidases, respectively, the samples were analysed for isopeptides. For this purpose, two chromatographic ion exchange systems were developed, each of which separates Nepsilon-(beta-aspartyl-)lysine (Asp Lys) as well as Nepsilon-(gamma-glutamyl-)lysine (Glu Lys) from the common amino acids. In samples, heated 24 h for at least 120 degrees C, 2-5% of the lysine residues are incorporated in Glu Lys-bonds. Under the heating conditions used in dairy practice, no isopeptide bonds were formed.

Animals↗
PubMed1979

Sequestration and turnover of guinea-pig milk proteins and chicken ovalbumin in Xenopus oocytes.

The stability and distribution of proteins within the living cell can be studied using Xenopus laevis oocytes. Microinjection of messenger RNAs and secretory proteins, followed by cell fractionation, shows that transfer of ovalbumin and milk proteins across intracellular membranes of the oocyte only occurs during their synthesis. Thus milk protein primary translation products, made in the wheat germ cell-free system, when injected into oocytes remain in the cytosol and are not recovered within membrane vesicles. Such miscompartmentalized primary milk proteins are rapidly degraded (t 1/2 0.6 +/- 0.1 h). In contrast, processed milk proteins, extracted from oocytes injected with mammary gland RNA, are relatively stable when introduced into the cytosolic compartment (t 1/2 alpha-lactalbumin 20 +/- 8 h, casein A 6 h, casein B 4 h, casein C 8.3 h). The primary ovalbumin product is also stable (t 1/2 22 +/- 9 h). Indirect evidence that rapid degradation of miscompartmentalized milk protein primary translation products may occur in vivo was obtained by the injection of massive amounts of ovalbumin and milk protein mRNA. Under these conditions there is no accumulation of primary milk protein translation products, but a polypeptide resembling the unglycosylated ovalbium wheat germ primary product can be detected in the cytosol. Only the glyclosylated forms of ovalbumin are found in the oocyte membrane vesicle fraction. We discuss the roles played by the presence of detachable signal sequences and the absence of secondary modifications in determining the rate of degradation of primary translation products within the cytosol.

Animals↗
PubMed1978

Lactose and major milk proteins are present in secretory vesicle-rich fractions from lactating mammary gland.

Preparations enriched in apparently intact secretory vesicles were isolated from homogenates of lactating rat and bovine mammary tissue by differential and density gradient centrifugation in isoosmotic media. Morphologically these preparations consisted nearly entirely of vesicles of varying sizes, at least some of which contained casein micelles. Endoplasmic reticulum vesicles, Golgi apparatus cisterna and dictyosomes, mitochondria, peroxisomes, lysosomes, and nuclei were not observed in secretory vesicle-rich fractions. Vesicle preparations were enriched in lactose relative to total membrane fractions from mammary gland. The galactosyltransferase of lactose synthase (UDPgalactose: D-glucose 4 beta-galactosyl-transferase, EC 2.4.1.22) was also present in secretory vesicle preparations, alphas1- and beta-caseins, alpha-lactalbumin, and beta-lactoglobulin, the major secretory proteins of differentiated mammary epithelial cells, were identified as constituents of vesicle-rich fractions from bovine mammary gland. These observations suggest that the major carbohydrate and major proteins of milk are compartmentalized into secretory vesicles and are secreted by exocytotic fusion of secretory vesicles with the apical plasma membrane.

Animals↗
PubMed1979

Do pre- and postchallenge small intestinal biopsies help to diagnose cow's milk protein intolerance?

Twelve infants suspected of cow's milk protein intolerance were challenged with cow's milk after at least one month of cow's milk-free diet. The challenge was clinically positive in seven. Small intestinal biopsies were taken with a multipurpose capsule both pre- and postchallenge (at 24 h) in eight, prechallenge in three, and postchallenge in one. Two or three biopsy specimens were taken at the same time in 15 of the 20 biopsy occasions. The morphology of the mucosa could vary from normal to slight damage at the same biopsy occasion. No difference was found in morphology judged by light microscopy between pre- and postchallenged biopsies. Light microscopy of small intestinal biopsies taken before and at 24 h after milk challenge seems of doubtful value as a routine diagnostic means in cow's milk protein intolerance.

Animals↗
PubMed1977

A study of serum antibodies to isolated milk proteins and ovalbumin in infants and children.

Serum antibodies to cow milk proteins and ovalbumin were measured quantitatively. Food hypersensitivity of the immediate type was determined to be present or absent by skin tests and double-blind food challenges. Elevated levels of antibodies to milk proteins in sera characteristic of infants fed cow milk were found to decline with age, so that sera from children who were 6 to 15 years of age (inclusive), not hypersensitive to food, had significantly lower levels than the infants. In contrast, sera from age-matched children, who were shown to have hypersensitivity to some food, were found to have levels of antibodies to milk proteins as elevated as in infancy. Hypersensitivity was not necessarily to milk but often to some other food. This persistence of greater antibody production to milk throughout childhood in those hypersensitive to some food indicates a fundamental difference from those without hypersensitivity to food, either in permeability, in immunological reactivity of the gut or in development of immunological unresponsiveness. Implications for pathogenesis of clinical disorders are discussed.

Adolescent↗
PubMed1978

Disaccharidase deficiency in infants with cow's milk protein intolerance. Response to treatment.

7 infants, aged 5 weeks to 11 months, with clinically documented intolerance to cow's milk protein, chronic diarrhea, and failure to thrive, underwent small intestinal (peroal, suction) biopsy before and after withdrawal of milk proteins. Mucosal specimens were examined by light microscopy and assayed for disaccharidase activities. In all patients, moderate to severe mucosal changes were presented, associated with marked inflammation of lamina propria and damages to the brushborder. Disaccharidase activities (lactase, sucrase, maltase and palatinase) were markedly depressed in all. Follow-up biopsies were obtained in 6 infants, after 3-5 months on a milk-protein-free diet. At the time of the second biopsy, the disaccharidase activities had risen significantly and histologic improvement had occurred in each instance. In infancy, intestinal mucosal lesions due to intolerance to cow's milk protein are histologically indistinguishable from those seen in gluten-sensitive enteropathy and are associated with marked secondary disaccharidase deficiencies. Following therapy, the activity of the disaccharidases become normal or near normal prior to the complete morphologic recovery of the small intestinal mucosa.

Animals↗
PubMed1979

Utilization of milk proteins as starting materials for other foodstuffs.

The modern food-processing industry is placing more and more emphasis upon the utilization of protein ingredients to provide specific functional properties to a wide range of formulated foods. Isolated milk protein products represent an important and valuable source of protein ingredients due to their recognized superior nutritional, organoleptic and functional properties. This paper provides up-to-date information on the quantities, production processes, composition, general properties, and specific functional properties of the major milk protein products, e.g. caseinates, co-precipitates, lactalbumin, whey protein concentrates and milk blends. The subject of chemical and enzymic modification to improve certain functional properties of milk proteins is considered briefly.

Animals↗