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Biomedical subjects

J Carlsson

Publications and source records attributed to J Carlsson.

At least 289 records · Page 16Linked to original sources
PubMed1983

Radiation sensitivity of human histiocytic lymphomas in vitro.

The radiation sensitivity of five human lymphoma cell lines has been investigated. All cell lines were originated from tumours clinically classified as histiocytic lymphomas. Using biochemical and immunologic techniques it was found that only one of them was a true histiocytic lymphoma. This cell line had an appreciable shoulder on the survival curve and capacity to repair sublethal damage. The survival curves of the other cell lines had no shoulders and the cells had nearly no capacity to repair sublethal damage. Taken together with previously published experimental and clinical observations the results indicate that tumours which by conventional diagnostic techniques are classified as histiocytic lymphomas are very heterogeneous in radiation sensitivity. It is possible that tumours of true histiocytic origin are more resistant to radiation than tumours of lymphocytic origin.

Cell Count↗
PubMed1983

Lactoperoxidase and thiocyanate protect cultured mammalian cells against hydrogen peroxide toxicity.

The toxicity of various combinations of lactoperoxidase-thiocyanate-hydrogen peroxide was tested on a cell line of human epidermoid carcinoma of the cervix (HeLa), a Chinese hamster ovary cell line (CHO), and human gingival fibroblasts. The capacity of the cells to proliferate, to exclude trypan blue and to produce acids from glucose was evaluated. There was no significant difference between the three cell types in their reactions to the various test combinations. A 1 h exposure of the cells to 10 microM hydrogen peroxide reduced their capacity to proliferate. After a 1 h exposure to 100 microM hydrogen peroxide the cells were damaged to such an extent that none survived. In the presence of lactoperoxidase and thiocyanate the cells were protected from the toxic effects of hydrogen peroxide as disclosed by their capacity to proliferate and exclude trypan blue. The rate of acid production of the cells in the presence of glucose was inhibited, however, by the combination lactoperoxidase-thiocyanate-hydrogen peroxide.

Animals↗
PubMed1982

Radiosensitivity of human B-lymphocytic lymphomas in vitro.

The radiosensitivity of four human B-lymphocytic lymphoma cell lines has been studied. For all lines the Do values were in the range 1.3 to 1.8 Gy. None of the survival curves had an appreciable shoulder. The extrapolation numbers varied in the range 1.0 to 1.2. Thus, the cell lines had a low capacity to accumulate sublethal damage. Furthermore, split dose experiments showed that no line had the capacity to repair sublethal damage. Taken together with earlier published experimental and clinical observations the results indicate that the use of an increased number of fractions in radiotherapy of B-lymphocytic lymphomas might be of great benefit to the patients. A schedule with an increased number of fractions will probably be as efficient in killing the tumour cells as previously used schedules but the tolerance of adjacent normal tissue will probably increase.

B-Lymphocytes↗
PubMed1982

Lactoperoxidase and thiocyanate protect bacteria from hydrogen peroxide.

Lactoperoxidase and thiocyanate were shown to protect Escherichia coli and three oral streptococcal species from the bactericidal effect of hydrogen peroxide under aerobic conditions. Lactoperoxidase in the absence of thiocyanate was also protective for two of the bacterial species in a dilution medium but potentiated hydrogen peroxide toxicity for the other two under the same conditions. The products of the reaction between hydrogen peroxide and thiocyanate in the presence of lactoperoxidase were not bactericidal except in the case of E. coli, and then only under special conditions. The results demonstrate the effectiveness of lactoperoxidase and thiocyanate in protecting living cells from hydrogen peroxide toxicity. Although the effect on human cells was not examined in this study, extrapolation of these results to the cells of the oral mucosa would suggest an important protective role of lactoperoxidase and thiocyanate against the toxic effects of hydrogen peroxide in the oral cavity.

Aerobiosis↗
PubMed1982

Potentiation by L-cysteine of the bactericidal effect of hydrogen peroxide in Escherichia coli.

Under anaerobic conditions an exponentially growing culture of Escherichia coli K-12 was exposed to hydrogen peroxide in the presence of various compounds. Hydrogen peroxide (0.1 mM) together with 0.1 mM L-cysteine or L-cystine killed the organisms more rapidly than 10 mM hydrogen peroxide alone. The exposure of E. coli to hydrogen peroxide in the presence of L-cysteine inhibited some of the catalase. This inhibition, however, could not fully explain the 100-fold increase in hydrogen peroxide sensitivity of the organism in the presence of L-cysteine. Of other compounds tested only some thiols potentiated the bactericidal effect of hydrogen peroxide. These thiols were effective, however, only at concentrations significantly higher than 0.1 mM. The effect of L-cysteine and L-cystine could be annihilated by the metal ion chelating agent 2,2'-bipyridyl. DNA breakage in E. coli K-12 was demonstrated under conditions where the organisms were killed by hydrogen peroxide.

2,2'-Dipyridyl↗
PubMed1982

Effects of sublethal doses of gamma radiation on the developing rat brain. synthesis of nucleic acids.

Newborn rats were irradiated with 60Co gamma rays. Doses of 0, 0.8 or 1.6 Gy were given to the whole body. The body and brain weights, DNA and RNA contents of the brain and 3H-thymidine or H-uridine incorporated by the brain were measured at 5, 10, or 15 days after birth. A dose of 1.6 Gy produced alterations in the brain weight and the DNA and RNA contents of the brain while no clear effects could be detected after 0.8 Gy.

Animals↗
PubMed1981

Penetration of substances into tumor tissue--a methodological study on cellular spheroids.

The penetration of [3H]thymidine, [3H]D-leucine, [125I]albumin, and the drugs [3H]5-fluorouracil and [3H]vinblastine into human glioma spheroids (in vitro tumor models) was studied by a method based on rapid freezing, freeze drying, vapor fixation, wax embedding, dry sectioning, and contact autoradiography. No significant disturbances in the distribution of water soluble substances were observed. Thymidine and D-leucine penetrated the whole spheroids relatively fast, whereas albumin showed reduced penetration. The concentration of albumin was highest at the periphery of the spheroids, but only smaller amounts were detected in the deeper regions. A significant difference between the penetration patterns of the drugs studied was also observed. Fluorouracil penetrated rather freely, but the penetration of vinblastine was limited.

Albumins↗
PubMed1981

Metabolic inhibition of Peptostreptococcus anaerobius decreases the bactericidal effect of hydrogen peroxide.

Peptostreptococcus anaerobius VPI 4330-1 was tested under various conditions for examination of the bactericidal effect of hydrogen peroxide. The cells were most rapidly killed by hydrogen peroxide when they were in the exponential-growth phase. Cooling or starving the cells decreased the bactericidal effect of hydrogen peroxide. The ionophore nigericin and the metal ion chelating agent 2,2'-bipyridine stopped macromolecular syntheses and greatly decreased the bactericidal effect of hydrogen peroxide. The ionophore valinomycin and the glycolytic inhibitor iodoacetate also stopped the syntheses of the macromolecules but only slightly decreased the bactericidal effect of hydrogen peroxide. Novobiocin, an inhibitor of deoxyribonucleic acid gyrase, and chloramphenicol, an inhibitor of protein synthesis, were not able to decrease the bactericidal effect of hydrogen peroxide. These findings implicate metal ions and an active metabolism of the organism in the bactericidal effect of hydrogen peroxide.

Antimetabolites↗
PubMed1981

Radiation effects on cultured human lymphoid cells. Analysis using the growth extrapolation method.

The cloning efficiency of human normal and malignant lymphoid cells is usually low. Radiation effects in vitro on such cells can therefore not be analysed with conventional cloning. However, this problem can be circumscribed by using the growth extrapolation method. A panel of human leukemia-lymphoma cell-lines representing Epstein-Barr virus carrying lymphoblastoid cells of presumed nonneoplastic derivation and neoplastic T- and B-lymphocytes was used to test the efficiency of this method. The sensitivity to radiation could be determined for all these cell types. The growth extrapolation method gave generally the same result as conventional cloning demonstrated by comparison with one exceptional cell-line with capacity for cloning in agar. The sensitivity varied largely between the different cell types. A common feature was that none of the cell lines had a good capacity to accumulate sublethal radiation injury.

Cell Division↗
PubMed1980

Evaluation of methods of transport and cultivation of bacterial specimens from infected dental root canals.

Five different methods of transport and cultivation of bacteria from dental root canal specimens were evaluated. Bacteria were recovered from 29 percent of the specimens when they were transported in VMG IV and subcultured in PRAS medium or on the surface of blood agar in an anaerobic box. When a PRAS-peptone-yeast extract broth was used for transport and the specimens were initially subcultured in the broth, bacteria were recovered from 49 percent of the specimens. When fluid thioglycollate medium USP (BBL) and Clausen medium (Oxoid) were used for transport as well as for initial subculture, bacteria were recovered from 58 percent and 47 percent of the specimens, respectively. The high recovery of bacteria by these media could to a significant degree be ascribed to the use of the media for initial subculture of the specimens. Recovery of bacteria by fluid thioglycollate medium USP was as good or even better as with the more elaborate PRAS medium. Fluid thioglycollate medium USP in screw-capped vials requires no special equipment in the dental clinic and is recommended for use in routine dental practice.

Anaerobiosis↗
PubMed1980

Survival of irradiated glia and glioma cells studied with a new cloning technique.

A method allowing cloning of monolayer cultured cells with a low plating efficiency was developed. Cells were grown in several small palladium squares to obtain a high cell density. These squares were surrounded by non-adhesive agarose to prevent large distance migration and thereby mixing of the clones. By using easily-cloned hamster cells for comparison it was found that the survival curves were similar to the curves obtained with conventional cloning. The new method was used to compare the radiosensitivity of cultured human glia and glioma cells which both have a low plating efficiency (less than 5 per cent) when seeded sparsely. The survival curves for the glioma cells had high Do-values (1.5--2.5 Gy) and large shoulders (extrapolation numbers around 5) indicating that they were rather resistant and had a high capacity for accumulation of sublethal damage. The survival curves for glia cells had lower Do-values (1.3--1.5 Gy) and no shoulders at all, indicating that they were more sensitive than the glioma cells.

Animals↗
PubMed1980

Demonstration of opsonizing antibodies to Francisella tularensis by leukocyte chemiluminescence.

Twenty-three individuals were vaccinated with a viable attenuated strain of Francisella tularensis, and blood was collected at various time intervals during 4 weeks. To demonstrate opsonizing antibodies, a mixture of serum and vaccine bacteria was incubated, whereafter the chemiluminescence response of polymorphonuclear (PMN) leukocytes to this mixture was recorded. No opsonizing antibodies against F. tularensis were found in sera obtained before vaccination. Eleven days after vaccination, sera from nine individuals, and 21 days after vaccination, sera from all 23 individuals contained antibodies. Antibodies were demonstrated earlier with the chemiluminescent technique that with the agglutination reaction. Heat treatment (56 degrees C, 30 min) or removal of complement component C3 from immune serum reduced the chemiluminescent response of the leukocytes. A high chemiluminescent response of the leukocytes was induced by immunoglobulin G (IgG)- and IgM-enriched fractions of immune serum in the presence of complement. In the absence of complement, the IgG fraction induced a low chemiluminescent response; the IgM fraction induced no response at all.

Antibodies, Bacterial↗
PubMed1980

Influence of complement on the chemiluminescent response of human leukocytes to immune complex.

Vaccine bacteria of Francisella tularensis were mixed with human serum containing specific antibodies against the same organism, and the mixture was incubated at 37 degrees C for 30 min. The mixture induced a two-peak chemiluminescent response in polymorphonuclear leukocytes. The initial peak was induced by a soluble agent, formed during incubation. The formation of this agent involved the activation of complement component C5. The second peak of the chemiluminescent response was induced by the opsonized bacteria; this peak was augmented by complement component C3, whereas C5 had no influence.

Antigen-Antibody Complex↗
PubMed1980

Bactericidal effect of hydrogen peroxide is prevented by the lactoperoxidase-thiocyanate system under anaerobic conditions.

Streptococcus sanguis and Peptostreptococcus anaerobius were exposed to various combinations of the components of the lactoperoxidase-thiocyanate-hydrogen peroxide system. The bactericidal effect of hydrogen peroxide was prevented under anaerobic conditions by lactoperoxidase together with thiocyanate, but not by lactoperoxidase or thiocyanate alone. Thiocyanate was effective already at a molar ratio to hydrogen peroxide of 1:100.

Anaerobiosis↗
PubMed1980

The recA+ gene product is more important than catalase and superoxide dismutase in protecting Escherichia coli against hydrogen peroxide toxicity.

Various deoxyribonucleic acid repair-deficient strains of Escherichia coli K-12 were exposed to hydrogen peroxide under anaerobic conling of the strains was determined. The level of catalase, peroxidase, and superoxide dismutase in cell-free extracts of the strains as well as the capacity of intact cells to decompose hydrogen peroxide were assayed, recA strains were more rapidly killed than other strains with deoxyribonucleic acid repair deficiencies. There was no correlation between the killing rate of the strains and the capacity of intact cells to decompose hydrogen peroxide or the level of catalase and superoxide dismutase in cell-free extracts. The level of peroxidase in cell-free extract was too low to be determined.

Catalase↗