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Biomedical subjects

H Svensson

Publications and source records attributed to H Svensson.

At least 127 records · Page 7Linked to original sources
PubMed1978

Cell population kinetics and dose-time relationships for post-irradiation injury of the brachial plexus in man.

Collected data on radiation-induced lesions of the brachial plexus were analyzed on the assumption that this reaction arises from depletion of some unidentified cell population in the irradiated tissues. A multi-probit search program was used to derive best-fitting cell kinetic parameters in a composite multi-target model for cellular radiation lethality and repopulation. From these parameters, a comprehensive iso-effect table, for a wide range of treatment schedules including daily treatment as well as fractionation at shorter and longer intervals, was constructed. The table provides a useful set of tolerance dosage limits for late effects in irradiated peripheral nerve.

Brachial Plexus↗
PubMed1977

A 22 MeV microtron for radiation therapy.

The first 22 MeV micron installation for radiation therapy is described with regard to the general design, the beam transport and the gantry. The first measurements of the electron depth dose curves indicate that the distributions obtained are superior to those of most betatrons and linear accelerators. For the same electron beam energy the depth of dose maximum and the 90 or 80 per cent dose level is considerably increased. The 20.9 MV photon beam has similar depth dose characteristics as a 20 MV betatron.

Electrons↗
PubMed1977

Ionization chamber dosimetry for photon and electron beams. Theoretical considerations.

New Clambda-values (Cair,lambda) are proposed which should be applied for ionization chambers with an inner wall of air-equivalent material, air eq. plastic or graphite. The new values are up to approximately 3 per cent lower, and apply for a chamber with an inner wall lining of water-equivalent material.er cent higher than those published in the ICRU Report No. 14 and here named Cwater,lambda as the inner wall is considered water-equivalent. Also two sets of CE-values are proposed, namely Cair,E which is given in ICRU No. 21 and Cwater,E which is approximately 3 p

Cobalt Radioisotopes↗
PubMed1976

Biogenesis of microsomal membrane glycoproteins in rat liver. IV. Characteristics of a cytoplasmic lipoprotein having properties of a membrane precursor.

The supernatant fraction from a rat liver homogenate contains a lipoprotein complex which can be incorporated into microsomal membranes in vitro. The lipoprotein can be purified by gel filtration and flotation in a NaBr solution. The isolated lipoprotein has an equilibrium density in the range of 1.07-1.14 g/ml, a sedimentation coefficient of 4.9 S and a calculated molecular weight of 210 000. The isolated complex contains 44% lipid by weight, half of which is phospholipid. The protein also has covalently bound sugar moieties, namely mannose, galactose, glucosamine, and sialic acid. The complex is unstable and may dissociate during the isolation procedure. The complex and its fragments contain two peptides with molecular weights of 11-13000 and 67-69000. These two components have practically identical amino acid compositions.

Amino Acids↗
PubMed1975

Biogenesis of microsomal membrane glycoproteins in rat liver. I. Presence of glycoproteins in microsomes and cytosol.

The glycoproteins of microsomes and cytosol were studied. Various washing procedures did not release the proteins from the microsomes, and immunological tests demonstrated that the sialoproteins are not serum components. Low concentrations of deoxycholate and incubation in 0.25 M sucrose solution liberated a small amount of microsomal sialoprotein and this fraction exhibited a high degree of labeling of protein-bound N-acetylneuraminic acid. A part of the glycoprotein fraction could not be solubilized, even with a high concentration of the detergent. Thoroughly perfused rat liver contained sialoproteins in the particle-free supernate. The level of sialoprotein present could not be due to contamination with serum or broken organelles. The high in vivo incorporation of [3H]glucosamine into protein-bound sialic acid of Golgi membranes and cytosol was paralleled by a delayed and lesser rate of incorporation into the rough and smooth microsomal membranes. This incorporation pattern suggests the possibility that the glycoproteins of cytosol and Golgi may later be incorporated into the membrane of the endoplasmic reticulum.

Acid Phosphatase↗
PubMed1975

Biogenesis of microsomal membrane glycoproteins in rat liver. II. Purification of soluble glycoproteins and their incorporation into microsomal membranes.

Sialoproteins isolated from the soluble fraction of rat liver could be incorporated into microsomal membranes. This incorporation was dependent on protein concentration, time, and temperature. Sodium dodecyl sulfate gel electrophoresis of membrane proteins after in vitro incorporation showed four major sugar-containing peaks and was similar to that found after in vivo labeling. Most of the incorporated protein was tightly bound to the microsomal membrane. Gel filtration and ion-exchange chromatography revealed the presence of several cytosolic glycoproteins that could be incorporated into microsomes. During prolonged centrifugation in a KBr solution with a density of 1.21 a highly labeled ([3H]glucosamine) protein (mole wt approximately to 70,000) that was actively incorporated into microsomes could be recovered in the upper region of the tube. These results demonstrate that several cytoplasmic glycoproteins of rat liver are transferred into microsomal membranes and that one of these is a lipoprotein.

Animals↗
PubMed1975

Biogenesis of microsomal membrane glycoproteins in rat liver. III. Release of glycoproteins from the Golgi fraction and their transfer to microsomal membranes.

The presence in the Golgi fraction of glycoproteins destined to be incorporated into the microsomal membrane was investigated. When incubated in sucrose, washed Golgi vesicles released four major, weakly acidic glycoproteins, some of which could be incorporated into microsomal membranes by incubation. Double labeling with [3H]glucosamine and [14C]leucine demonstrated the incorporation of both protein and oligosaccharide moieties, and the main peak of radioactivity was associated with the 70,000 mol wt region after SDS-gel electrophoresis. The proteins that could be incorporated into microsomes were probably associated to a large extent with the outer surface of the Golgi membrane. Centrifugation of the proteins released from the Golgi in a KBr solution (p = 1.24) resulted in a separation of glycoproteins, those in the top layer most actively incorporated into microsomes. The lipoglycoproteins in the top layer that could be incorporated appeared in the 70,000 mol wt region after SDS-gel electrophoresis, as did the corresponding proteins isolated from the supernate. These results suggest that glycoproteins with completed oligosaccharide chains are released from the Golgi system to the cytosol and are subsequently transferred to microsomes as constitutive membrane components.

Animals↗
PubMed1975

Electron depth absorbed dose distribution for a 10 MeV clinical microtron.

Central axis depth absorbed dose distributions of the electron beam from a medical microtron accelerator have been measured. The measured distributions differ from those of existing betatrons and linear accelerators. A larger absorbed dose build-up and a sharper dose fall-off are obtained in close agreement with theoretical calcuations for monoenergetic electron beams. The differences from other accelerators are explained by the narrow energy spectrum, the clean geometry and the small amount of scattering material in the electron beam of the microtron.

Electrons↗
PubMed1975

Electron depth absorbed doses for small phantom depths. Comparison between different accelerators.

Depth dose distributions at small phantom depths in polystyrene were measured with a liquid ionization chamber at six different accelerators. The absorbed dose at 0.5 mm depth relative to the absorbed dose maximum in the central beam varied between 0.77 and 0.92 for 10 MeV electrons. Generally the surface absorbed dose increased with increasing energy or decreasing field size. Results from measurements off axis indicate small differences from the data available for the central beam.

Electrons↗