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Biomedical subjects

B Axelsson

Publications and source records attributed to B Axelsson.

At least 73 records · Page 4Linked to original sources
PubMed1984

Measurement of intracranial blood volume by gamma camera emission tomography.

Based on phantom and animal experiments a method is proposed for measuring the intracranial blood volume ( ICBV ) by gamma camera emission tomography. The intracranial radioactivity from 99mTc -tagged erythrocytes in intracranial vessels is measured with a gamma camera rotating around the head of the dog with a circulatory turn of 2-20 min. The radioactive counts from each cycle are pictorially displayed as 8-12 frontal sections through the head. On each section the intracranial space is delineated as the region of interest and counted separately. The sum of the intracranial counts of the various sections is an expression of the ICBV and linearly related to it. Accurate delineation of the intracranial space on each of the displayed slices is achieved by injection of a nondiffusible isotope ( 169Yb -DTPA) into the subarachnoid space at the end of each experiment. Scattered radiation is corrected for by a correction factor obtained from the phantom experiments. By means of special calibration procedures the measured ICBV , as expressed in counts may be transferred into volume units (ml). The present method seems to offer several advantages compared to earlier methods for measuring the ICBV .

Animals↗
PubMed1984

Subtraction of Compton-scattered photons in single-photon emission computerized tomography.

A technique for scatter correction in single photon emission computerized tomography (SPECT) is described. The method is based on "deconvolution" of scattered events from the measured profile data. The function defining the scatter distribution was determined from measurements with a line source in circular and rectangular water phantoms. The accuracy of the method was tested on a simple phantom simulating a SPECT investigation of the liver. The indicated ratio of the activity concentration in a photon-deficient area, 60 mm diameter in the "liver", relative to its surroundings, was 0.28/1 without scatter correction and 0.01/1 with the correction.

Liver↗
PubMed1983

Column separation of monocytes by adherence to gelatin beads.

This investigation was performed to study whether the efficient binding of collagen to monocytes in the presence of fibronectin and heparin may be used for separation of monocytes from human peripheral blood. It was shown that monocytes adhere selectively to gelatin bead columns in the presence of fresh plasma and heparin. Mononuclear blood cells are rapidly depleted of monocytes by passage through a 5-10 ml column at a flow rate of 1.5-2.0 ml per min. Adhering lymphocytes are more loosely attached and may be detached by stirring and washing, while the monocytes can be eluted by 50 mM EDTA. This separation technique is suitable for combination with various other methods since it is rapid, allows convenient handling of large numbers and yields cells with very high viability. Although most B lymphocytes pass through the column without attaching, there is some enrichment of B cells and non-T, non-B cells among the adherent lymphocytes.

Animals↗
PubMed1983

Non-uniformity induced artifacts in single-photon emission computed tomography.

Changes of gamma camera uniformity due to choice of flood source configuration and camera head orientation, and influence of these changes on the reconstructed image, have been analysed using phantom measurements. The transfer of defects in the projection data to the reconstructed image has also been investigated using computer simulations. The results indicate that the use of gamma cameras for emission computed tomography will impose higher demands on gamma camera uniformity than conventional scintigraphy.

Models, Biological↗
PubMed1982

Transferrin receptors on mitogen-stimulated human thymus-derived lymphocytes.

The appearance of transferrin receptors on mitogen-stimulated human thymus-derived (T) lymphocytes was studied. When indirect immunofluorescence with immunoadsorbent-purified antitransferrin antibodies was used, approximately 10% of resting T cells were stained. This proportion increased to 50-80% of the cells 3-4 days after stimulation with the mitogenic lectins concanavalin A (Con A) and leucoagglutinin (La) from Phaseolus vulgaris. Almost all blast cells (greater than or equal to 90%) were positive. Cell binding experiments with 125I-labelled transferrin indicated the presence of 1-5 x 10(5) transferrin receptor molecules/cell with high avidity for transferrin (K = 2 - 12 x 10(8) l/mol). Analysis by sodium dodecyl sulphate polyacrylamide gel electrophoresis and autoradiography of cell lysates containing 125I-labelled T-cell surface components revealed two surface peptides (90 kdaltons and 80 kdaltons, reducing conditions), which selectively bound to insolubilized antitransferrin antibodies. The 90-kdalton peptide also bound to insolubilized transferrin. The 80-kdalton peptide is most probably transferrin and the 90-kdalton peptide the transferrin receptor. Unreduced transferrin receptor had a molecular weight of 180 kdalton. It is probably a glycoprotein, since it reacted with wheat germ agglutinin, La, and probably also Con A. The properties of the lymphocyte transferrin receptor are similar to those described for transferrin receptors on various in-vitro-grown transformed cells. This speaks in favour of a common receptor present on all proliferating human cells.

Concanavalin A↗
PubMed1981

Liposome immune assay (LIA). Use of membrane antigens inserted into labeled lipid vesicles as targets in immune assays.

A new method is described for detection of membrane antigens and antibodies against such structures. By inserting partially purified rat transplantation antigen (RT-1) into iodine or fluorescein-labeled lipid vesicles, a precipitation of the liposome is demonstrated by the use of a specific alloantiserum and a heterologous anti-rat IgG serum. Precipitation of liposomes carrying WF transplantation antigens could be detected at a final dilution of the alloantiserum of 1:3000, which is comparable to that obtained in a 51Cr-release assay. Furthermore, when unpurified membrane proteins from WF splenocytes were incorporated into labeled liposomes, an amount of RT-1 corresponding to 8000 cells could be detected.

Animals↗
PubMed1979

Radiation doses in low-dose pelvimetry using rare-earth screens.

A 'low-dose technique' of obstetric pelvimetry, using rare-earth screens and a reduced ambition level of image quality, yields an estimated absorbed dose to the maternal and foetal gonads of 0.9 and 0.01 mGy, respectively. The resulting risk for 'hereditary ill health' and the risk for induction of leukemia from the absorbed dose to the foetal red bone marrow, have been calculated to be at a very low level.

Female↗
PubMed1978

Helix pomatia A hemagglutinin: selectivity of binding to lymphocyte surface glycoproteins on T cells and certain B cells.

Human and mouse lymphocytes were surface-labeled by lactoperoxidase-catalyzed iodination, or by galactose oxidase oxidation followed by reduction with tritiated sodium borohydride. The labeled cells were lysed with Nonidet P-40. Proteins binding to Helix pomatia A hemagglutinin (HP) were isolated by affinity chromatography on HP-Sepharose and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiography. A major cell surface glycoprotein (apparent mol. wt. 150 000, using reducing conditions) on human lymphocytes was responsible for almost all binding of HP. This protein was present on normal and malignant thymus-derived lymphocytes, e.g. thymocytes, blood T cells and T leukemia cell lines. It was also found on chronic lymphocytic leukemia cells, one null cell leukemia line, one unidentified leukemia line, one lymphoblastoid cell line of B origin and on one stem cell lymphoma line. In contrast, this protein was not found on various B cells at different steps of differentiation, e.g. four B lymphoma lines or one myeloma line. It was also absent from a histiocytic leukemia line. However, two of the four B lymphoma lines and the myeloma line had another HP-binding surface glycoprotein (mol. wt. 200 000) instead of the 150 000 protein. Studies of mouse lymphocytes similarly showed that thymus-derived lymphocytes (normal and malignant) but not normal adult B cells expressed a major HP-binding surface glycoprotein of apparent mol. wt. 130 000 (reducing conditions).

Agglutinins↗
PubMed1978

Comparison of gamma camera and withdrawal methods for the measurement of gastric emptying.

In ten healthy volunteers the emptying of 300ml 15% glucose solution from the stomach was determined with two independent methods; a gamma camera method using 99mTc-DTPA as indicator and a withdrawal method, modified after Hunt, with PEG as indicator. At 40 min the gastric contents were withdrawn, and the stomach washed out. The quantity of indicator in the withdrawal and washout fluids was determined with both methods. A close correspondence was found between the methods.

Adult↗
PubMed1978

Radiation dose related to collimator geometry in the first generation EMI scanner.

The radiation dose from the first generation EMI scanner has been analysed, including the variation of the dose perpendicular to the section, the dose dependence of the size and collimation of the beam, and the fraction of radiation passing the patient and utilized for information. The possible dose in case of malfunctions of the scanner was also measured.

Adult↗
PubMed1978

A sequential extraction method for RNA from rabbit liver.

When naphthalene-1,5-disulfonate (NDS) and phenol-cresol were used for extraction of rRNA from rabbit liver approximately 80% of the extractable RNA was recovered. By subsequent treatment of the resulting insoluble interface with 4-aminosalicylate and triisopropylnaphthalenesulfonate (PAS-TIPNS) the remaining RNA was extracted. Subcellular fractionation and polyacrylamide gel electrophoresis or sucrose density gradient analysis showed that this last fraction contrained 28s RNA from membrane-bound polysomes. Applying the sequential extraction method for isolation of poly(A)-containing mRNA showed that only a minor part of that RNA was extracted with NDS while the rest was recovered by PAS-TIPNS treatment of the interface. Thus, a purification of poly(A)-containing mRNA was possible when the sequential extraction method was used.

Aminosalicylic Acids↗
PubMed1977

Preparation of poly (A)-binding proteins from endoplasmic reticulum-containing subfractions of rat liver cells and their use in mRNA purification.

Approximately 2% of the proteins solubilised from rat liver microsomes or rapidly sedimenting endoplasmic reticulum (RS-ER) adsorbed to poly(A)-Sepharose. The adsorption appeared to be selective for a few proteins, and proteins of different apparent molecular weights adsorbed from RS-ER and the microsomes. The proteins from RS-ER with affinity for poly(A) were coupled to Sepharose and used for the purification of mRNA from rabbit mammary glands. A portion of the RNA wihich did not adsorb to poly(U)-Sepharose adsorbed to protein-Sepharose and was active in a cell-free protein synthesis system.

Animals↗
PubMed1977

An investigation of the slice geometry of the EMI head scanner.

The slice geometry of the EMI head scanner is investigated. It is shown that the slice thickness is positionally dependent. The slice is thinner in the central part than on the periphery and also thinner on the tube side than on the detector side. It is also shown that there is a missing region between slices A and B.

Head↗
PubMed1977

Detection of sacro-ilitis. A comparison between profile scanning with the use of 99m Tc pertechnetate and scintigraphy with 99m Tc diphosphonate.

Comparative evaluation of the sensitivity of 99mTc pertechnetate scanning and of 99mTc diphosphonate scintigraphy in detecting sacro-iliac arthritis (S.I.) was performed in 32 patients with definite S.I., 14 with probable S.I., and 6 with inactive S.I., 14 patients without any evidence of S.I. served as controls. Greater diagnostic accuracy was obtained by 99mTc pertechnetate scanning than with 99mTc diphosphonate scintigraphy in patients with active S.I. in the early stages before radiological changes had become evident and in patients 22 years old and younger. In patients with inactive S.I. a close correlation was found between clinical, radiological, and scintigraphical results with 99mTc diphosphonate scintigraphy. An index obtained by adding the uptake values measured by both methods in each subject yielded valuable information in patients with S.I. that is clinically difficult to differentiate.

Adolescent↗