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Biomedical subjects

L Hambraeus

Publications and source records attributed to L Hambraeus.

At least 55 records · Page 3Linked to original sources

Protein evaluation of mixed diets. Comparative study in man and in the pig and rat of vegetable-animal and vegetable protein diets.

The procedure suggested by FAO/WHO to evaluate the protein quality of mixed diets has been tested using vegetable and vegetable-animal protein diets. Chemical scores were calculated and protein digestibilities were compared in human adult, growing pigs and rats. Pigs were studied as alternatives to rats in the protein evaluation of human diets. The results showed that the choice of the samples to calculate the chemical score is important; that the composition of the samples for biological evaluations must be considered in order to avoid experimental problems, and that values for true protein digestibility in human subjects, pigs and rats are in agreement, and further studies of growing pigs as an experimental model are suggested. Minor differences in protein quality of the two diets were demonstrated.

Adult↗

Serum antibodies reactant with Korean haemorrhagic fever agent in Scandinavian epidemic (endemic) nephropathy (nephropathia epidemica) demonstrated by immunofluorescence utilizing an in vitro antigen source.

A newly developed spot slide immunofluorescence method utilizing an in vitro antigen source was used for the first time for the assay of antibodies reactant with the Korean haemorrhagic fever (KHF) agent in sera from patients diagnosed with Scandinavian epidemic (endemic) nephropathy (nephropathia epidemica, NE) and from age-matched control patients living in the same area as the NE patients but suffering from other diseases. KHF antibodies were demonstrated in all of 14 NE patients who were followed prospectively, 7 of whom exhibited seroconversion and in 6 of 8 NE patients studied retrospectively, but in only one of 42 controls. Antibodies in NE appeared within the first week of onset of symptoms and persisted for long periods of time as seen in KHF. The time from the onset of the illness until maximum antibody titre was recorded varied from 9 days to 1 month. On an average, the level of the antibody titres measured in NE was lower than that usually encountered in the Korean disease. The results indicate a close antigenic relationship between the KHF and NE agents and demonstrate that the reliability of our new spot slide method is similar to that of another previously reported and more laborious immunofluorescence method using lung from infected rodents as antigen source.

Adolescent↗

Effect of oral contraceptives on composition and volume of breast milk.

Nitrogen and protein composition was determined in milk from women using oral contraceptives during lactation. Total nitrogen and nonprotein nitrogen as well as lactose and the individual milk proteins lactoferrin, alpha-lactalbumin, and serum albumin were analyzed before introduction of oral contraceptives and thereafter throughout the lactation period. Twenty-four hour milk volumes were registered by weighing the infant before and after each feeding. The four oral contraceptives used consisted of different combinations of d-norgestrel, megestrolacetate, and ethinylestradiol. Significant changes were observed between groups and controls for all parameters studied. However, the changes observed were generally within the physiological variation of normal breast milk. It is suggested that the use of oral contraceptives during lactation should be limited.

Contraceptives, Oral↗

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↗

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↗

The protein quality of instant blends for infants and children based on milk or cereals and milk.

The protein quality of industrially produced and home prepared milk or cereal-milk based foods for infants and children were evaluated by means of biological assays. The net protein utilization (NPU) values of human milk substitutes based on cow's milk varied between 75 and 78 and the NPU of a soy-based product was found to be 70. Cereal-milk based precooked gruel powders had NPU values of 69 to 77. Furthermore, a comparison between industrially processed products and their corresponding home prepared alternatives was made. Although the protein nutritional products, i.e., including the vitamine and mineral content, is more standardized due to supplementation. The NPU assays of some cereal-milk based porridge powders revealed a wide variations (28 to 69); the lowest NPU values reflect the influence of the processing technique. This illustrates the necessity of performing biological evaluations of processed foods.

Animals↗