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Biomedical subjects

G Bengtsson

Publications and source records attributed to G Bengtsson.

At least 73 records · Page 4Linked to original sources
PubMed1978

Patient exposures and radiation risks in Swedish diagnostic radiology.

Results are reported of measurements around 1974 on a thousand patient at 13 Swedish hospitals, and additionally at several photofluorographic and dental installations. Energy imparted as well as doses to the thyroid, breast, lung, bone marrow, ovary and testis have been calculated for many types of examination. Collective doses have been calculated and risk estimates made. The energy imparted corresponds to an annual mean body dose to the Swedish population of about 1 mGy (100 mrad), and the genetically significant dose was about the same as the 1955 total of 0.4 mGy; in both cases the uncertainty of the estimate is about +/- 50%. The possibility of dose reduction by a factor of 2 or more using available techniques is demonstrated. The risk of future serious injury is estimated to 0.0002 cases per joule of energy imparted to the patient.

Bone Marrow↗
PubMed1977

Interaction of lipoprotein lipase with heparin-Sepharose. Evaluation of conditions for affinity binding.

Lipoprotein lipases from a variety of sources have been shown previously to bind to heparin and some related polysaccharides. For the present studies lipoprotein lipase purified from bovine milk was used. 1. In batch experiments binding of the enzyme activity to heparin-Sepharose occurred relatively slowly, so that 30min was required for the system to come to near-equilibrium. In contrast, release of the enzyme activity from heparin-Sepharose by addition of salt to the liquid phase occurred rapidly. 2. Some binding was observed also with unsubstituted Sepharose, but this binding had a low capacity compared with that observed with heparin-Sepharose. High salt concentrations, heparin or deoxycholate decreased the binding to unsubstituted Sepharose. These factors also increase the solubility of the enzyme, which is low. 3. Addition of heparin to the liquid phase caused a concentration-dependent release of enzyme activity from the gel. These results suggested that the binding of the enzyme to heparin-Sepharose was mainly through interaction with heparin. 4. The enzyme activity was also quantitatively displaced to the liquid phase at increased concentrations of salt. Among the positive ions tested the following order of effectiveness was noted: Cs(+) approximately K(+)>Na(+)>Li(+); and among the negative the following: SCN(-)>I(-)> NO(3) (-)>Br(-) approximately Cl(-). The differences were quite large. Thus addition of 0.16m-KSCN (in addition to the 0.32m-NaCl originally present) displaced one-half of the enzyme activity to the supernatant, whereas 0.8m-LiCl only displaced one-quarter. 5. The distribution of heparin in the gel also profoundly influenced the binding. Two series of gels were studied. One series was made by mixing heparin-Sepharose with unsubstituted Sepharose. Results obtained with these gels were those expected from a series of decreasing volumes of heparin-Sepharose. In contrast, a series of heparin-Sepharoses made with different degrees of substitution gave quite different results. With these gels the amount of enzyme activity bound per amount of heparin increased markedly, whereas the salt concentration needed to displace the enzyme activity from the gel decreased markedly with decreased concentration of heparin in the gel. 6. On stepwise elution of small columns of heparin-Sepharose the enzyme activity was eluted over a remarkably wide range of salt concentrations. When enzyme eluted at one salt concentration was re-applied, it gave the same elution profile as enzyme previously eluted at other salt concentrations or the entire enzyme preparation. These and other results suggested that, whereas the enzyme preparation was rather homogeneous in its binding to heparin, the heparin preparation was polydisperse in binding of lipoprotein lipase.

Animals↗
PubMed1977

Protein components of very low density lipoproteins from hen's egg yolk.

Egg yolk lipoproteins of very low density were found to contain proteins with cofactor activity for lipoprotein lipase. When delipidated very low density lipoproteins were dissolved in 10 mM HCl and fractionated by gel filtration about two thirds of the protein were in several components with estimated molecular weights of 60000 to more than 170000. The major low-molecular-weight proteins were the dimeric and monomeric forms of a previously characterized 9000-dalton peptide. The cofactor activity was not associated with any of these major proteins. A large-scale fractionation method was developed by which two proteins fractions with cofactor activity for lipoprotein lipase were purified more than thousand-fold. One fraction had a molecular size of about 9000 daltons and the other had a size of about 5000 daltons. Both these fractions could be further separated on the basis of charge into several fractions with cofactor activity. The cofactor proteins were relatively soluble both at high and at low pH. The retained their cofactor activity after denaturation in guanidinium hydrochloride and after reduction. During the initial steps in the purification of the cofactor proteins another low-molecular-weight protein followed the cofactors. It had a single 17500-dalton peptide chain and was present in four variants, three of which contained carbohydrate.

Amino Acids↗