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Biomedical subjects

T Berg

Publications and source records attributed to T Berg.

At least 343 records · Page 19Linked to original sources
PubMed1976

In vitro diagnosis of atopic allergy. V. The value of repeated testing using several batches of the allergen extract.

The radioallergosorbent test (RAST) has been used for in vitro diagnosis of allergy in a selected group of children with asthma and allergic rhinoconjunctivitis. The results were compared with those of provocation tests and also with the results of skin tests. Where the results of RAST and the provocation tests differed, repeated tests were performed, initially in vitro and secondly in vivo. Selected commercial allergens of good quality were used and, for the most part, the same allergen batches were used in RAST, in the provocation tests and in the skin tests. A 76% correlation between RAST and provocation tests was found on preliminary investigation before divergent results were repeated. This degree of correlation is similar to that obtained previously in unselected patients using RAST as a part of the routine diagnostic. On repeated examination, agreement was obtained in an additional 16% of the cases. The major part of the improvement (13%) was due to conversion of preliminary RAST results from negative to positive in children with positive provocation tests. To a minor extent, the improvement was due to the fact that in, some children with positive RAST, negative provocation tests became positive when repeated. Finally, in one case an originally positive RAST in a child with a negative provocation test was found to be negative on re-examination. Comparing the final revised results of RAST and provocation tests there were no cases where a negative provocation test was combined with a positive RAST. Nearly all the children with positive provocation tests in spite of a negative RAST were shown to have low degree allergy. Although circulating reaginic antibodies are not always present, it seems that, on repeated investigations, the great majority of children with asthma and hay fever can be shown to have such antibodies even though the serum concentration may be low or very low. In doubtful cases repeated RAST examinations may be of value.

Allergens↗
PubMed1975

Induction of tryptophan oxygenase by dexamethasone in isolated hepatocytes. Dependence on composition of medium and pH.

Hepatocytes were isolated from perfused rat livers. 4 x 10-6 cells/ml were incubated at at 37 degrees C in different media in the absence and presence of a steroid hormone, dexamethasone phosphate (2 x 10-5 M). 1. Hormonal enzyme induction occurred in cells suspended in a simple salt medium, devoid of amino acids and macromolecules. This induction was completely blocked by addition of either actinomycin D (2 mu-g/ml) or cycloheximide (50 mu-g/ml). 2. Incubation of cells in media containing defatted albumin did not enhance hormonal enzyme induction, although disintegration of cells during incubation was reduced. Addition of a crude albumin fraction reduced tryptophan oxygenase induction and dextran completely blocked enzyme induction by dexamethasone. 3. An increase of dexamethasone concentration in the presence of albumin to 9 x 10-5 M was unable to raise enzyme induction further, and a still higher concentration of hormone, 3 x 10-4 M, resulted in reduced enzyme induction. 4. The hormonal induction of tryptophan oxygenase was most pronounced when the pH of the medium was between 7.0 and 7.6, with an optium at 7.3. No induction was found when the pH of the medium was either 6.6 or 7.8. The basal tryptophan oxygenase activity was much less influenced by similar pH variations. It is concluded that hepatocytes in suspension are able to carry out hormone-stimulated enzyme synthesis and that factors influencing this process may be studied under controlled conditions in such systems.

Animals↗
PubMed1975

Altered hormone control of cyclic AMP formation in isolated parenchymal liver cells from rats treated with 2-acetylaminofluorene.

The hormone control of cyclic AMP-formation in isolated parenchymal liver cells from rats fed the carcinogen 2-acetylaminofluorene (0.025% for 4-8 weeks) was studied. The cells from the carcinogen-treated animals responded much more strongly to adrenergic agents than cells from control animals, while no significant difference was found for the glucagon effect. Of the adrenergic substances studied, the order of potency was isoprenalin larger than or equal to adrenalin larger than phhenylephrine; stimulation was blocked by propranolol, but not by phentolamine. The effects of supramaximal concentrations of isoprenalin and glucagon were not additive.

Animals↗
PubMed1975

Mass isolation and culture of rat kupffer cells.

Collagenase perfusion of the liver followed by pronase treatment of the cell suspension thus obtained gave a quantitative recovery of viable nonparenchymal liver cells (NPC). From these NPC, Kupffer (K) cells can be purified by attachment to tissue culture dishes. Tail vein injection of carbon 1-2 h before liver perfusion permitted stepwise calculation as well as visualization of carbon-containing K cells. When these K cells have been put into tissue culture medium with serum and incubated overnight, they exhibit typical macrophage characteristics. Phase-contrast and transmission electron microscopy showed typical macrophage morphology and scanning electron microscopy revealed well-spread cells with cytoplasmic projections and ruffled membranes. Endocytosis studies using radioactive colloidal gold and inert latex particles also indicated that these cells are highly active in pinocytosis and phagocytosis. Further characterization of K cells is the identification of Fc receptor on their membranes. Studies on lysosomal enzymes showed that purified K cells possess higher specific activities in beta-glucuronidase, acid DNase, and cathepsin D than in purified parenchymal cells.

Animals↗
PubMed1975

The influence of Cortisone on the hepatic uptake of Triton WR-1339 in adrenalectomized rats.

The effect of cortisone acetate on the hepatic uptake of Triton WR-1339 was studied in adrenalectomized rats. The hormone was found to retard the uptake of Triton in the liver, and at the same time reduce the plasma clearance of this compound. The inhibitory effect of the hormone on endocytosis was seen in purified preparations of both Kupffer cells and parenchymal cells. Triton renders the liver lysosomes progressively lighter. The change in equilibrium density (in sucrose gradients) was found to occur more rapidly in hormone-treated animals. The possibility that cortisone reduces the number and increases the size of the lysosomes is discussed. Our data indicate that the uptake of Triton in non-parenchymal (Kupffer) cells represents about 20% of the total hepatic uptake.

Adrenal Glands↗
PubMed1975

The concentrations of retinol-binding protein, prealbumin, and transferrin in the sera of newly delivered mothers and children of various ages.

Umbilical-cord blood from 50 full-term newborns and capillary or venous blood from 226 children varying in age from 6 weeks to 16 years was examined for content of retinol-binding protein (RBP), prealbumin, and transferrin. The mean levels of the three proteins in the newborns were 21 mug/ml, 128 mug/ml, and 1.65 mg/ml, respectively. The corresponding maternal levels were 39 mug/ml, and 3.2 mg/ml. Paired serum values of mothers and newborns showed a correlation for both RBP and prealbumin but not for transferrin. The low levels of RBP at birth (about 50 per cent of that of nonpregnant women) increased rapidly over the first 6 months to a maximum of 31 mug/ml but declined thereafter to a mean level of about 26 mug/ml, which was maintained until the age of puberty when adult values were gradually attained. In serum, the prealbumin levels showed a similar development, whereas the transferrin values reached constant adult levels as early as 2 years of age.

Adolescent↗