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Biomedical subjects

E Forsum

Publications and source records attributed to E Forsum.

52 records · Page 3Linked to original sources
PubMed1978

Effects of proteins and their corresponding amino acid mixtures on nitrogen balance and body composition in the growing rat.

The efficiencies of nitrogen utilization from intact proteins (casein, gluten, soybean, egg albumin) were compared to that of the respective synthetic amino acid mixtures. Food intake, growth, NER (nitrogen efficiency ratio), (Nitrogen retained/Nitrogen intake) X 100, BV (biological value), TD (true digestibility), liver weight and body composition were estimated on growing rats. Rats fed amino acid mixtures simulating casein, egg albumin and soybean consumed more food and showed more rapid growth than rats fed the intact proteins. Differences in nitrogen utilization and body composition were occasionally observed between the respective intact protein and amino acid mixtures but were in most cases not significant. It is concluded that nutrition with intact proteins cannot be assumed to be equivalent to nutrition with the corresponding amino acid mixture. However, general differences between the two types of feeding regimens were not obvious since the results were influenced by factors such as the amino acid composition of the protein and the amino acid mixture as well as the methodology used for nutritional evaluation. (Nitrogen retained/Nitrogen intake) X 100 and BV but not NER of an amino acid mixture formulated according to a commercial elementary diet was found to be low compared to casein.

Amino Acids↗
PubMed1978

Nitrogen and protein components of human milk.

The true protein content of human milk is 0.9%, in well-nourished as well as malnourished mothers. Casein constitutes only about 20% of the protein nitrogen in human milk. The remaining 80% is derived from the whey proteins, the three dominant components being alpha-lactalbumin, lactoferrin and secretory IgA. alpha-lactalbumin is a subunit of lactose synthetase. Lactoferrin is an iron-binding glycoprotein which plays a role in the defence against gastro-intestinal infections and is probably also involved in iron transport in the gut. Secretory IgA is comparatively stable at low pH; it is resistant to proteolytic enzymes and plays an essential role in the immunological defence against gastro-intestinal infections. Lysozyme is a minor component of the whey proteins and represents an active enzyme with a bactericidal effect. The nutritional and immunological significance of the marked differences with respect to the nitrogen and protein compositions of human milk and cow's milk should not be underestimated, but need further elucidation.

Animals↗
PubMed1976

A longitudinal study of the protein, nitrogen, and lactose contents of human milk from Swedish well-nourished mothers.

The contents of total nitrogen, nonprotein nitrogen, lactose, and individual milk proteins have been determined in human milk from well-nourished Swedish mothers. Breast milk samples from 50 mothers at different stages of lactation (up to 170 days) were collected. Furthermore, three mothers gave samples repeatedly throughout the whole lactation period. The protein content in mature milk was found to be 0.8 to 0.9% by amino acid analysis. The nitrogen content and the contents of the major human milk whey proteins, alpha-lactalbumin and lactoferrin, are very high for the first few days, then decrease rapidly and reach, thereafter, the more slowly declining level of mature milk. Nonprotein nitrogen and the nonspecific milk protein serum albumin are present in constant concentrations throughout lactation. The daily milk volumes were determined and found to be 500 to 600 ml in the very early part and 700 to 800 ml in the later part of the lactation period.

Female↗
PubMed1976

Breast milk composition in Ethiopian and Swedish mothers. II. Lactose, nitrogen, and protein contents.

Breast milk from underprivileged and privileged Ethiopian mothers was collected at different stages of lactation and analyzed for total nitrogen, nonprotein nitrogen, lactose, and individual milk proteins (lactoferrin, alpha-lactalbumin, serum albumin, IgG and IgM). These values and the milk volume of one meal were compared to corresponding results from well-nourished Swedish mothers. No significant differences between the levels of these constituents or the milk volumes were found between the two groups of Ethiopian mothers. When comparison was made between breast milk from these two Ethiopian groups and the Swedish group, the former two showed significantly higher values for the iron-binding protein lactoferrin.

Ethiopia↗
PubMed1976

Determination of alpha-lactalbumin in human milk.

Alpha-lactalbumin is a major protein in human milk and of considerable nutritional importance to the infant. However, there are discrepancies in the literature on content of this protein in human milk, which indicate a need for a method that would permit estimation from a large number of samples. The technique of immunodiffusion was adopted for human alpha-lactalbumin. Purification of alpha-lactalbumin for production of antigen is described as is the statistical evaluation of the method. The alpha-lactalbumin contents of pooled human milk samples as well as of the milk from one mother during 2 mo of lactation were analyzed. The alpha-lactal-bumin content of human milk showed considerable variation. This variation and its relation to factors such as length of lactation, and nutritional status of the mother should be studied further.

Amino Acids↗
PubMed1975

Use of a whey protein concentrate as a supplement to maize, rice and potatoes: a chemical and biological evaluation using growing rats.

Liquid whey has long been known to contain proteins of high nutritional value, but their use in human nutrition has been complicated by the high lactose and low protein contents of the whey. Modern technological processes of gel filtration and ultrafiltration have made possible the production of whey protein concentrates (WPC) low in lactose. In this investigation, the supplementary effect of WPC on maize and rice proteins was compared with the corresponding effect of dried skim milk (DSM). Protein quality was studied by chemical and biological methods on growing rats. Biological tests performed on both raw and boiled protein mixtures showed WPC to be superior to DSM in supplementing maize and rice proteins. The nutritive value of a potato-WPC mixture was also studied and compared with those of potato-lactalbumin and potato-egg mixtures, both of which are known to contain protein of very high quality for man. The comparison indicated that a potato-WPC mixture may also possess high protein quality.

Amino Acids, Essential↗