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Biomedical subjects

J Carlsson

Publications and source records attributed to J Carlsson.

At least 199 records · Page 11Linked to original sources
PubMed1991

Effects of amiloride treatment on U-118 MG and U-251 MG human glioma and HT-29 human colon carcinoma cells.

Human glioma (U-118 MG, U-251 MG) and human colon carcinoma (HT-29) spheroids and monolayers were continuously exposed to amiloride under physiological Na+ and HCO3- conditions. Amiloride in concentrations of 0.1-0.2 mM inhibited growth, while 0.5 mM or higher induced disintegration of the glioma spheroids within 4-6 days. Growth retardation of the HT-29 spheroids was achieved at concentrations of 0.4-0.5 mM and total growth inhibition and disintegration were achieved at 1.0 mM. Monolayer cultures of glioma cells were also more sensitive to amiloride than those of colon carcinoma cells. The higher amiloride concentrations induced pyknotic nuclei mainly in the central areas of the spheroids where the extracellular pH (pHe) was low. The amiloride-sensitive glioma spheroids had lower pHe than the colon carcinoma spheroids. The intracellular pH (pHi), measured in monolayers, was higher (7.11-7.18) in glioma cells than in colon carcinoma cells (6.94). High concentrations of amiloride, 1.0 mM for 1 h in combination with low Na+ concentrations, caused a strong pHi decrease in glioma cells but only a slight decrease in the colon carcinoma cells. The pHi measurements in glioma monolayers were carried out after 2-6 days of continuous exposure to 0.1 mM amiloride at physiological levels of Na+ and HCO3- to simulate the conditions during growth inhibition. After several days this caused, when growth already was inhibited, an acidification of pHi. Parallel measurements with X-ray microanalysis showed an increase of intracellular sodium and a decrease of intracellular potassium in the gliomas, while no such changes were seen in the colon carcinoma cells under identical conditions. It is concluded that the two glioma cell lines were more sensitive to amiloride, both as monolayers and spheroids, than the corresponding cultures of the colon carcinoma cell line. The inhibition of proliferation by amiloride seemed not to have a clear connection to pHi regulation.

Amiloride↗
PubMed1991

Studies on Pf155/RESA and other soluble antigens from in vitro cultured Plasmodium falciparum.

Spent culture medium from in vitro cultures of Plasmodium falciparum was used as the source for immunoadsorbent enrichment of soluble parasite antigens. IgG obtained from P. falciparum-hyperimmune Liberian serum was used as the ligand in the immunoadsorbent. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the immunoadsorbent isolated material revealed the presence of at least 15 antigenic and parasite-derived polypeptides. Immunoblotting after SDS-PAGE showed greater than 20 antigenic polypeptides in the molecular weight range of 15-250 kDa. Several of these were heat-stable (100 degrees C for 5 min), and six of them were detected even after heating for 60 min. Among the latter antigens was Pf155/RESA, a merozoite antigen deposited in the erythrocyte membrane at invasion. Pf155/RESA can be detected using a modified erythrocyte membrane immunofluorescence (EMIF) assay. Inhibition of EMIF with heated parasite material showed that the antigenic activity was intact after heating for up to 30 min. The immunofluorescence-inhibitory activity was separated into two fractions, one containing Pf155/RESA and one containing polypeptides with molecular weights of 135 and 120 kDa. All three of these antigenic polypeptides bound selectively, albeit nonspecifically, to aminoethyl-BioGel resins.

Animals↗
PubMed1991

Heterogeneity in antigenic expression and radiosensitivity in human colon carcinoma cell lines.

A panel of human colon carcinoma cell lines were characterized regarding both antigenic heterogeneity and variations in radiosensitivity. Monoclonal antibodies were used to study the expression of carcinoembryonic antigen (CEA), gastrointestinal cancer antigen (GICA or CA 19-9) and carcinoma-associated antigen (CA-50). Radiosensitivity was studied with the clonogenic survival technique. Three cell lines, LS 174T, HCTC, and SW 1116 stained positive for all three antigens. HT-29 was positive for CA 19-9 and CA-50 whereas Caco-2 was positive for CEA and CA 19-9. The cell lines SW 620 and LIM 1215 only stained positive for one of the antigens, CA-50 and CEA, respectively. In nearly all positive cases the stainings were very heterogeneous with mixtures of positive and negative cells. One exception was the HCTC cells which stained homogeneously for the CA 19-9 and CA-50 antigens. The neuroendocrinelike COLO 320 cells were negative in all cases. The radiosensitivity varied strongly between the cell lines with Dq-values between 0.8 and 1.9, extrapolation numbers between 2.0 and 4.7, Do-values between 1.1 and 2.8. The surviving fraction at 2 Gy varied between 0.3 and 0.7 with HCTC as the most radiosensitive and HT-29 as the most radioresistant cell line. Thus, there were differences in antigenic expression and intrinsic radiosensitivity between the cell-lines and antigenic heterogeneities within each cell line. The analyzed panel of cell lines will be valuable in studies of dose-effect relations for monoclonal antibodies labeled with toxic radionuclides simulating both antigenic heterogeneity and variations in radiosensitivity.

Adenocarcinoma↗
PubMed1991

Plasmodium falciparum: analysis of the interaction of antigen Pf155/RESA with the erythrocyte membrane.

The location of the Plasmodium falciparum vaccine candidate antigen Pf155/RESA in the membrane of infected erythrocytes was analzyed by means of selective surface radioiodination and immunofluorescence of surface-modified cells. The lack of radiolabel in Pf155/RESA as well as its localization by immunofluorescence similar to that of the N-terminal region of erythrocyte band 3 suggests that the antigen is associated with the cytoplasmic phase of the erythrocyte membrane. In concordance with this, Pf155/RESA was detected by immunofluorescence on the surface of inside out membrane vesicles from P. falciparum-infected erythrocytes. Pf155/RESA from spent culture medium also bound to inside out membrane vesicles of normal erythrocytes as well as to cytoskeletal shells of such vesicles, but failed to bind to sealed right-side out membrane vesicles. Depletion of spectrin from the vesicles abolished antigen binding, suggesting that Pf155/RESA association with the erythrocyte cytoskeleton is mediated by spectrin.

Amino Acid Sequence↗
PubMed1991

Plasmodium falciparum: an invasion inhibitory human monoclonal antibody is directed against a malarial glycolipid antigen.

A Plasmodium falciparum malaria blood stage antigen was detected using a human monoclonal antibody (MAb A52A6) obtained from a clinically immune donor. Immunofluorescence analysis showed that the MAb reacted with the intracellular parasite throughout the asexual blood stage cycle as well as with gametocytes. The MAb also reacted with the surface of erythrocytes containing late stage P. falciparum parasites. The antigen seen by the MAb was species- but not strain- or isolate-specific. At rupture of the infected erythrocytes, antigenic material was deposited on the membrane of uninfected cells surrounding the parasite. At merozoite invasion MAb reactive material was present on the invaginating erythrocyte membrane, indicating an involvement of the antigen in the invasion process. This was also indicated by the high capacity of the MAb to inhibit merozoite invasion in vitro. The antigen appears to be a phosphoglycolipid, sensitive to phospholipase and present in lipid extracts of P. falciparum-infected erythrocytes.

Animals↗
PubMed1991

Distribution and stability in the rat of a 76Br/125I-labelled polypeptide, epidermal growth factor.

A positron-emitting isotope of bromine, 76Br, with a half-life of 16.2 h, was produced using the reaction natBr(p, xn)76Kr. Labelling of mouse epidermal growth factor (EGF) with 76Br was optimized, using the chloramine-T method, obtaining a maximal radiochemical yield of 53%. In tests with receptor-rich, cultured glioma cells, [76Br]EGF and [125I]EGF bound equally well. A study of the distribution and stability of [76Br]EGF and [125I]EGF in normal rat was carried out. The distribution of both radioisotopes was similar, however, the percentage of 76Br bound to the high molecular weight fraction in the plasma, liver and kidney was greater than that of 125I.

Animals↗
PubMed1991

Radioimmunolocalization of human colonic cancer xenografts; aspects of extensive purification of monoclonal anti-CEA-antibodies.

Tumour-to-normal tissue ratios of i.p. injected 125I-labelled monoclonal antibodies (MAbs), reacting with CEA were determined in nude rats xenografted with human colonic cancer cells (LS 174 T). Two MAbs, I-38S1 and II-16, reactive with the GOLD 1-epitope on CEA were tested. MAb I-38S1 was also tested after additional purification using anion exchange chromatography (thereafter named AEC 38). In the external activity measurements, MAb AEC 38 showed significantly better tumour-to-liver ratios than did MAb II-16 on all 4 days after injection. MAb I-38S1 gave intermediate ratios but was significantly better than II-16 only on day 3. The mean tumour-to-blood ratios were 3.0, 2.6 and 1.5 and the mean tumour-to-liver ratios were 6.6, 4.8 and 3.5 for MAbs AEC 38, I-38S1 and II-16 respectively. Gamma camera registrations in 3 animals on 4 days showed good imaging properties for all three MAbs and the patterns of tissue uptake were consistent with those seen in the external measurements. Furthermore, histopathological and immunohistochemical determinations were performed, showing that MAb II-16 gave about the same spatial binding as the previously analysed MAb I-38S1. The results indicate that additional purification of MAbs using anion exchange chromatography may potentiate tumour uptake in this model.

Carcinoembryonic Antigen↗
PubMed1991

Effects of the PAF-analog and -antagonist CV-6209 on cultured human glioma cell lines.

Cell lines of human glioma (U-343 MGa and U-251 MG) and human glia (U-533 CG) origin were cultured as monolayers and exposed to CV-6209, an alkyl-phospholipid analog and antagonist of platelet activating factor. This drug had very potent antiproliferative effects on the studied human glioma cell lines; IC50 was 0.9 microM after 48 h treatment and 0.2 microM after 2 weeks treatment. At these doses no growth inhibitory effect was noted on the normal glia cells. The effects on the glioma cells were reversible in the dose intervals, where cell proliferation, 3H-thymidine and 14C-methionine uptakes were greatly inhibited. The simultaneous administration of platelet activating factor [(R)PAF] did not influence the antiproliferative effects of CV-6209 on the cells cultured as monolayers. The structurally similar analog CV-3988 also had antiproliferative effects, although at 10 times higher concentration than CV-6209. Two other, structurally unrelated, PAF-antagonists (WEB-2086 and TCV-309) gave effects only at very high concentrations. The U-343 MGa cell line was also exposed to CV-6209 when growing as multicellular spheroids. The studies on the spheroid cultures also demonstrated good antitumoral effects with decreases of both the volume growth and the thymidine uptake. The simultaneous administration of (R)PAF reversed the inhibitory effect of CV-6209 on thymidine incorporation. This study demonstrates a strong antitumoral effect at low concentrations of CV-6209. The antiproliferative effects were probably primarily related to the ether-lipid structure and not to the PAF-antagonistic properties. The good antitumoral effect of CV-6209 on both monolayer and spheroid cultures and the possible PAF-antagonistic properties are discussed.

Cell Division↗
PubMed1991

Immunocomplex-immobilization technique.

An immunoassay technique is presented, which works equally well with either a radioactive isotope or an enzyme as the label. It is based on the competition between a labelled antigen of known concentration and an unlabelled antigen (concentration to be determined) for binding to an antibody, which previously has been thiolated by the heterobifunctional reagent N-[3-(2-pyridyldithio)propionyl]succinamide [marketed as N-succinimidyl-3-(2-pyridyldithio)propionate; SPDP)]. The soluble immunocomplex formed is then immobilized onto agarose beads containing reactive disulphide groups. After washing, to remove any unbound and non-specifically adsorbed material, the radioactivity or the enzymic activity on the agarose beads is determined and the concentration of the antigen in the test sample calculated according to the conventional procedure for a competitive immunoassay. In order to demonstrate the applicability of the technique a test procedure for the determination of total serum immunoglobulin E is presented.

Immunoglobulin E↗
PubMed1991

Influence of chloroquine and lidocaine on retention and cytotoxic effects of [131I]EGF: studies on cultured glioma cells.

Targeting of toxic substances to the epidermal growth factor, EGF, receptor might be an attractive therapeutic approach because of the increased receptor-expression in some human tumours such as, for example, malignant gliomas and squamous lung carcinomas. Radiation effects of [131I]EGF on human malignant glioma cells growing as monolayers were analysed in this study. The cells were, in all cases, incubated for 25 min with about 350 kBq/ml [131I]EGF, which gave a total binding of 3.2-3.5 kBq/10(5) cells. The rapid release of activity from the cells caused by the normal degradation of EGF was inhibited by incubation with 30 microM chloroquine or 5 mM lidocaine added to the cell culture medium. These substances are, at these concentrations, known to inhibit proteolytic processes in lysosomes. No effects of the inhibitors alone were observed on cell growth and clonogenic survival. Inhibition of EGF degradation by chloroquine or lidocaine resulted in a significantly prolonged association of 131I with the test cells. About 70% of the initially bound radioactivity remained in the cells giving, after 6 h, a binding of 2.1-2.5 kBq/10(5) cells. A 6 h exposure to the radiation from 131I decays, mediated mainly by specifically bound EGF, gave a survival value of about 50%. Such an effect corresponds to a treatment of 2.5 Gy 60Co gamma-radiation. This is promising considering that, when monolayers are applied, only a very small fraction of the released energy from the 131I decays is deposited in the cells. Effects from non-receptor bound [131I]EGF were analysed after presaturation of the receptors with non-radioactive EGF, and gave no or very small changes in survival.

Cells, Cultured↗
PubMed1991

Effect of sulfide ions on complement factor C3.

In infected sites such as the gingival pockets of patients with periodontal disease, sulfide levels up to 1 mmol/liter may be reached. There is little information, however, on how sulfide may interact with the host defense. In a previous study (R. Claesson, M. Granlund-Edstedt, S. Persson, and J. Carlsson, Infect. Immun. 57:2776-2781, 1989), it was shown that polymorphonuclear leukocytes were able to kill bacteria in the presence of 1 mM sulfide. However, sulfide seemed to interfere with the opsonization of the bacteria. It has been claimed that sulfide may be toxic by splitting disulfide bonds of proteins. In the present study, serum was exposed to 2 mM sulfide under anaerobic conditions, and the capacity of sulfide to split disulfide bonds of 10 serum proteins involved in opsonization was evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunodetection of the proteins after blotting. Sulfide had a low capacity to split the disulfide bonds of most proteins. Sulfide had, however, a pronounced effect on the complement component C3 in the form of C3bi. Sulfide released the C-terminal region of the alpha chain from C3bi. When C3 opsonizes bacteria, it is this region of C3bi which binds to complement receptor 3 (CR3) of the polymorphonuclear leukocytes. If sulfide has the same effect on C3bi deposited on the bacterial surface as it has on C3bi in solution, it will annihilate the very important contribution of C3bi to opsonization.

Complement C3↗
PubMed1991

Backscatter radiation at tissue-titanium interfaces. Analyses of biological effects from 60Co and protons.

It has been claimed that implanted metals can cause backscatter radiation in radiation therapy with a dose enhancement at the bone-metal and tissue-metal interfaces on the beam entrance side. Theoretical calculations and experimental measurements with ionization chambers have indicated that such effects might be significant. Titanium implants are increasingly used in oral and maxillo-facial surgery for reconstruction purposes. A more detailed knowledge of backscatter-induced effects is therefore desired when head and neck cancers in patients with implants are treated with radiotherapy. We have made comparisons of cell survival after irradiation of two types of cultured cells grown directly on titanium metal and on plastic control supports. The cell cultures were irradiated with either 60Co photons or range modulated protons. No significant differences in the colony-forming capacity were found between the irradiated cells grown on titanium and those grown on plastic control supports. This was the case for both radiation types and the results were also observed to be dose-independent. The only observed phenomena were that the two cell-lines differed in radiosensitivity and that protons gave higher biological effects than gamma radiation. The results show that there were no significant changes in cell survival at the interface between the tissue equivalent medium and titanium support indicating that a dose increase induced by backscatter radiation, which possibly could demolish the osseointegration or induce osteoradionecrosis, are minimal when high energy photons or range modulated protons are applied.

Animals↗
PubMed1991

The narrow proton beam therapy unit at the the Svedberg Laboratory in Uppsala.

The synchrocyclotron at the The Svedberg Laboratory (TSL) in Uppsala is now reconstructed and can presently operate with fixed frequency and proton energies up to 100 MeV. A first treatment room with a narrow proton beam unit for therapy of eye tumours is now in operation. Therapy of eye melanomas started in April, 1989 and during 1989 and 1990, 19 patients were treated with 72 MeV protons. The narrow beam unit provides a fixed horizontal beam and the patient is treated in a seated position. The present paper describes mainly the technical aspects of the unit which so far has been used only for eye melanomas. In the future, modifications of the unit will allow therapy of intracranial targets when higher proton energies are available. In its final form, the proton therapy facility at TSL will harbour a second treatment unit. Here a rotating gantry for 200 MeV protons will provide a broad beam, which will enable treatment of tumours located anywhere in the body.

Eye Neoplasms↗
PubMed1991

Binding of epidermal growth factor (EGF) to a cultured human glioma cell line.

We have studied binding of 125I-EGF to the human malignant glioma cell line U-343 MG aCl2:6, which is planned to be used as a model system in studies of toxic effects of EGF conjugates. Special care has been taken to fulfil the requirements for a correct Scatchard analysis of binding parameters. Binding as a function of time, temperature and pH was investigated as well as dissociation and internalization of bound EGF. The stability of EGF during incubation was also determined. After binding to the receptor, EGF is rapidly internalized and degraded at physiological temperature. We found that binding experiments should be performed at 4 degrees C, since at this temperature practically no internalization took place, whereas dissociation occurred. From displacement experiments using increasing concentrations of unlabelled EGF competing with 125I-EGF for binding, binding parameters were calculated using a computerized, nonlinear, least-squares regression analysis of binding data. We found that EGF bound to a class of high affinity receptors with an apparent dissociation constant KD of about 4 x 10(-10) M. The mean number of receptors was 25,000 per cell. In experiments where receptors were saturated with 125I-EGF an additional class of low affinity receptors was detected. This had an apparent KD of 1 x 10(-8) M with a mean receptor number per cell of 780,000. We also noticed enhanced dilution-induced dissociation of bound 125I-EGF in the presence of excess unlabelled EGF, suggesting negative cooperativity.

Cell Count↗
PubMed1991

Application of (methyl-11C)-methionine in the multicellular spheroid system.

Human glioma (U-343 MGa) and human colon carcinoma (HT-29) cell lines were cultured as multicellular spheroids, and the accumulations of the L- and D-enantiomers of 11C-methionine were investigated. The accumulation of radioactivity in the spheroids was expressed as relative counts, by dividing the radioactivity measured in the spheroid with the radioactivity of the same volume of the incubation medium. The experiments were verified using 14C-labeled L- and D-methionine. The influence of spheroid volume, specific activity, incubation time, washing time, and the environmental temperatures were investigated. The spheroid model was used to determine the effect of the lipoxygenase inhibitors BW A4C and AA-861, the ether-phospholipid type PAF-antagonist CV-6209 and the protein synthesis inhibitor cycloheximide on methionine uptake. The results showed that 11C-L-methionine can be applied in the study of drug effects on multicellular tumor cell aggregates.

Benzeneacetamides↗
PubMed1991

Oxygen and the sugar metabolism in oral streptococci.

Streptococci have several ways of adapting themselves to the constantly changing environment of the human oral cavity. This paper discusses the adaptation of sugar metabolism to variations in oxygen levels. In all streptococci the Embden-Meyerhof pathway of glycolysis works under aerobic as well as anaerobic conditions, but pyruvate is converted into different metabolic end products depending on the oxygen levels. Under anaerobic conditions all streptococci form formate, acetate, and ethanol by a pyruvate formate-lyase pathway. If sugar is in excess, they also form lactate using a lactate dehydrogenase. Under aerobic conditions pyruvate formate-lyase is inactivated. This enzyme is then replaced by a pyruvate oxidase in some streptococci and by a pyruvate dehydrogenase in others. The characteristics of these enzymes help streptococci like S. sanguis, S. oralis, S. gordonii, and S. mitis to compete successfully with other bacteria in those sites of the oral cavity that are freely exposed to saliva, while mutans streptococci have to colonize anaerobic sites such as those in-between the teeth and in the occlusal fissures of the teeth.

Glucose↗
PubMed1990

Failure of betamethasone to alter the radiation response of two cultured human glioma cell-lines.

Glucocorticoids, such as betamethasone, are often used to prevent possible acute reactions during radiation therapy of intracranial tumors (for example gliomas). The effect of the glucocorticoids is probably due to vascular changes decreasing the development of edemas. The radiosensitivity of two studied cell-lines of human malignant glioma origin did not significantly change when they were continuously exposed to betamethasone in the concentration range of 1-25 micrograms/ml. The radiosensitivity was measured with the extrapolation method, which gave an estimate of cell survival, and through direct measurements of growth delays from growth curves. The results obtained are in conformity with previously published results where clonogenic survival tests showed that the isomer dexamethasone did not change the radiosensitivity of these cells. Thus, no direct effects on the radiosensitivity of glioma cells are expected from glucocorticoid treatment and it is therefore unlikely that the poor results obtained from radiation therapy of malignant gliomas are due to an increased radioresistance brought on by the glucocorticoid treatment.

Betamethasone↗