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S O Kolset

Publications and source records attributed to S O Kolset.

At least 55 records · Page 3Linked to original sources
PubMed1991

Macromolecular properties of glycosaminoglycans in primary AL amyloid fibril extracts of lymphoid tissue origin.

We have previously demonstrated the presence of glycosaminoglycans (GAGs) in water extracts of secondary AA amyloid fibrils. In the present study we isolated significant quantities of GAGs from fibril extracts of immunoglobulin light chain (AL) type derived from the spleens from two patients afflicted with primary amyloidosis. Employing ion-exchange chromatography and gel filtration subsequent to various specific chemical and enzymatic treatments, different types of high molecular weight GAGs were found in both preparations, but not in the corresponding normal splenic extracts. The amyloid-associated GAGs of the extracts derived from one patient consisted of 60% dermatan sulphate and 40% heparan sulphate whereas those obtained from the second spleen were 25% dermatan sulphate and 75% heparan sulphate. The heparan sulphate fraction occurred in the form of proteoglycans, whereas the dermatan sulphate apparently occurred as free GAG chains, resembling the data recently obtained from AA amyloid fibril extracts.

Amyloid↗
PubMed1991

The effect of stress in vivo on the function of mouse macrophages in vitro.

Macrophages were harvested from home cage control (HCC) mice, and from mice which had been stressed by repeated brief exposures (3-8 min) to cold water at 10-15 degrees C twice daily for 8 or 14 days. Macrophages obtained from mice stressed 8 or 14 days compared to macrophages from HCC mice showed in vitro increased amounts of membrane-bound prothrombinase activity, whereas the thrombin degradation activity was unchanged. Furthermore, macrophages of mice stressed 8 days showed increased release of coagulation factor X/Xa to supernatant in vitro. These findings suggest an increased amount of prothrombinase complex enzymes on the surface of macrophages from mice stressed 8 days, and increased activity of the prothrombinase enzyme in macrophages from mice stressed 14 days. The synthesis of proteoglycans (PG) and glycosaminoglycans (GAG) was increased in macrophages from mice stressed 8 days compared to macrophages from HCC mice and mice stressed 14 days. When macrophages from mice stressed 8 days or HCC mice were stimulated in vitro with phorbol myristate acetate (PMA) and IL-1 or PMA and IL-2, a changed PG/GAG synthesis was observed only in macrophages from the HCC animals. Furthermore, both the tumour cytotoxicity and the released tumour necrosis factor (TNF) were decreased from macrophages from mice stressed 14 days compared to HCC mice. The results suggest that the macrophages of stressed mice have an altered mode of function more complex than a simple general suppression or activation.

Animals↗
PubMed1991

High molecular weight glycosaminoglycans in AA type amyloid fibril extracts from human liver.

Glycosaminoglycans have previously been identified in extracts of AA type hepatic amyloid fibril from a patient with amyloidosis associated with juvenile rheumatoid arthritis. The macromolecular properties of these polysaccharides are described here in more detail. By gel filtration and ion exchange chromatography glycosaminoglycans in the form of high molecular weight free chains were shown to coisolate with water extracted amyloid fibrils. About 60% of these were characterised as galactosamines (chondroitin sulphate/dermatan sulphate), whereas the remaining 40% consisted of N-sulphated glucosamines (heparin/heparan sulphate). The amyloid associated glycosaminoglycans were not part of intact proteoglycans in the fibril extracts.

Amyloidosis↗
PubMed1991

Identification of glycosaminoglycans in human renal and splenic secondary AA amyloid fibril preparations.

The evidence that glycosaminoglycans (GAGs) are specifically associated with amyloid, is strong. In the present study we looked for GAGs in water extracts of amyloid fibrils from kidney and spleen laden with AA amyloid secondary to ankylosing spondylitis. Significant amounts of high molecular weight GAGs were isolated from the fibril preparations of both organs using ion-exchange chromatography and gel filtration procedures. The polysaccharides present in purified human renal and splenic amyloid fibril material were characterized as follows: a) Sulphated GAGs of high molecular weight were found in both renal and splenic amyloid fibril extracts, but not in extracts from corresponding normal tissues. b) All of the renal amyloid-associated high molecular weight GAGs were chondroitin sulphate/dermatan sulphate, whereas splenic amyloid-associated high molecular weight GAGs had a chondroitin sulphate/dermatan sulphate:heparan sulphate ratio of approximately 2:1. c) The findings gave no evidence that GAGs coisolated with AA amyloid fibrils were parts of intact proteoglycan molecules with several GAG chains.

Adult↗
PubMed1990

Proteoglycans in haemopoietic cells.

Proteoglycans are produced by all types of haemopoietic cells including mature cells and the undifferentiated stem cells. The proteinase-resistant secretory granule proteoglycan (serglycin; Ref. 14), is the most prevalent and best characterised of these proteoglycans. Although its complete pattern of distribution in the haemopoietic system is unknown, serglycin has been identified in the mast cells, basophils and NK cells, in which secretion is regulated, and in HL-60 cells and a monocytoid cell line (Kolset, S.O., unpublished data) in which secretion is constitutive. Proteinase-resistant proteoglycans have been detected in human T-lymphocytes and murine stem cells (FDCP-mix) and the core proteins may be closely related to serglycin. A variety of glycosaminoglycan chains are assembled on the serglycin protein and it is likely that this class of proteoglycan can carry out a wide variety of functions in haemopoietic cells including the regulation of immune responses, inflammatory reactions and blood coagulation. There is strong evidence that in mast cells, NK cells and platelets, the proteoglycans are complexed to basic proteins (including enzymes and cytolytic agents) and amines in secretory granules and such complexes may dissociate following secretion from the cell. The stability of the complexes may be regulated by the ambient pH which may be acidic in the granules and neutral or above in the external medium. However, proteinase-proteoglycan complexes in mast cell granules seem to remain stable after secretion and it has been proposed that the proteoglycan regulates activity of proteinases released into the pericellular domain. The functions of proteoglycans which are constitutively secreted from cells are less clear. If cells have no requirement for storage of basic proteins why do they utilise the same design of proteoglycan as cells which accumulate secretory material prior to regulated release? We should stress that the so-called constitutive secretory pathway has been identified in haemopoietic cells in culture, which are usually maintained and grown in the presence of mitogenic factors (e.g., IL-2, IL-3). the cells are therefore activated and it has not been established that continuous proteoglycan secretion occurs in quiescent cells circulating in the peripheral blood. It is possible that lymphocytes, monocytes and macrophages, in which the constitutive secretion pathway operates in vitro, may store proteoglycan in vivo unless stimulated by mitogens or other activating agents.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

The effect of beta-D-xylosides on the proliferation and proteoglycan biosynthesis of monoblastic U-937 cells.

The monoblastic cell line U-937 was cultured in the presence of C-ethyl beta-D-xyloside (E-xyl), hexyl beta-D-thioxyloside (HX-xyl), p-nitrophenyl beta-D-xyloside, phenyl beta-D-xyloside or phenyl alpha-D-xyloside. All of the beta-D-xylosides inhibited proliferation, but HX-xyl was by far the most efficient, and had a maximum effect at 1 mM concentration. The inhibitory effect of HX-xyl could be reversed; after washing, the HX-xyl-treated cells proliferated with a pattern similar to that of control cells. For more detailed analysis of the effects of beta-D-xylosides on cell proliferation and chondroitin sulphate (CS)/chondroitin sulphate proteoglycan (CSPG) structure, a comparison between the effects of E-xyl and HX-xyl was made. Treating the cells with 1 mM-HX-xyl resulted in a large increase in CS synthesis, whereas 1 mM-E-xyl had only minor effects on the rate of PG/glycosaminoglycan synthesis. Sepharose CL-6B gel chromatography of medium and cell fractions from 35S-labelled cells revealed that HX-xyl treatment resulted in the expression of only free CS chains, whereas E-xyl exposure leads to the synthesis of both large and small CSPGs, as well as some free CS chains. The expression of elevated levels of free CS chains was clearly correlated to the inhibition of proliferation. The proliferation of U-937-4, a clone of U-937 synthesizing ten times more CSPG/CS than the parent line, was equally inhibited by HX-xyl treatment. With this clone, however, there was no stimulation of CS synthesis after xyloside exposure, indicating that the elevated level of CS evident after xyloside treatment of the parent cell line is not causing the inhibition of proliferation. Furthermore, the biosynthesis of hyaluronate was shown not to be implicated in the xyloside-induced decrease in proliferation. The inhibition of proliferation observed in the presence of 1 mM-HX-xyl did not lead to differentiation of the cells into macrophage-like cells, as is observed when the cells are cultured in the presence of phorbol esters, agents also known to inhibit proliferation of U-937 cells.

Antigens, Surface↗
PubMed1989

[Proteoglycans--are distributed throughout the body and have many functions].

Proteoglycans constitute a defined group of carbohydrate-containing proteins. The carbohydrate chains which are denominated glycosaminoglycans contain sulfate and are negatively charged at physiological pH. Proteoglycans are strong polyanions and can bind a long range of macromolecules such as collagen, histamin and antithrombin, and they participate in processes such as regulation of coagulation, maintenance of connective tissue structure, storage of amines intracellularly, and regulation of hemopoesis. Genetic defects in the turnover of proteoglycans lead to conditions known as mucopolysaccharidoses. The best known proteoglycan in the clinic is the antithrombotic agent heparin.

Humans↗
PubMed1989

Modulation of the expression of chondroitin sulfate proteoglycan in stimulated human monocytes.

Proteoglycan biosynthesis was studied in human monocytes and monocyte-derived macrophages (MDM) after exposure to typical activators of the monocyte/macrophage system: interferon-gamma (IFN-gamma), lipopolysaccharide (LPS), and phorbol 12-myristate 13-acetate (PMA). By morphological examination, both monocytes and MDM were stimulated by these activators. Treatment with IFN-gamma resulted in a slight decrease in the expression of [35S]chondroitin sulfate proteoglycan (CSPG) in both monocytes and MDM, whereas LPS treatment increased the [35S]CSPG expression 1.8 and 2.2 times, respectively. PMA, in contrast, decreased the CSPG expression 0.4 times in monocytes, whereas MDM were stimulated to increase the biosynthesis 1.9 times. An increase in the sulfate density of the chondroitin sulfate chains was evident following differentiation of monocytes into MDM due to the expression of disulfated disaccharide units of the chondroitin sulfate E type (CS-E). However, monocytes exposed to PMA did also express disaccharides of the chondroitin sulfate E type. Furthermore, the expression of CS-E in MDM was increased 2 times following PMA treatment. An inactive phorbol ester, phorbol 12,13-diacetate, did not affect the expression of CS-E in either monocytes or MDM when compared with control cultures, suggesting that protein kinase C-dependent signal pathways may be involved in the regulation of sulfation of CSPG. Exposure to LPS or IFN-gamma did not lead to any changes in the sulfation of the chondroitin sulfate chains.

Cells, Cultured↗
PubMed1989

Binding of metastatic colon carcinoma cells to liver macrophages.

The liver is frequently colonized by metastatic tumor cells despite its dense population of macrophages (Kupffer cells). We have studied the interactions between metastatic colon carcinoma cells (DHD) and syngeneic Kupffer cells under different experimental conditions in vitro. In an adhesion assay the binding of DHD cells to Kupffer cell monolayers was shown to be time and temperature dependent, reaching a maximum level after about 90 min of incubation at 37 degrees C. In contrast, only a low level of binding could be observed at 4 degrees C. The level of binding could be increased by pretreatment of the Kupffer cells with phorbol 12-myristate 13-acetate. A firm interaction between the two cell types was shown to be dependent on the presence of calcium- and trypsin-sensitive structures on the surface of the Kupffer cells. Pretreatment of the macrophages with the cytoskeletal inhibitors colchicine and cytochalasin B was also found to reduce significantly the binding of tumor cells. This binding was also inhibited to a large extent by D-mannose and N-acetyl-D-galactosamine. The Kupffer cells were not cytotoxic against the colon carcinoma cells.

Animals↗
PubMed1989

Presence of glycosaminoglycans in purified AA type amyloid fibrils associated with juvenile rheumatoid arthritis.

Previous studies have strongly suggested an association between glycosaminoglycans and tissue deposits of amyloid. The present study was aimed at studying this association in purified preparations of hepatic amyloid fibrils obtained from human AA type secondary amyloidosis. Glycosaminoglycans were isolated by gradient ion exchange chromatography of purified amyloid fibrils treated with pronase. Degradation with specific enzymes identified the glycosaminoglycans as chondroitin sulphate, dermatan sulphate, and heparin/heparan sulphate. The total amount of glycosaminoglycans specifically coisolated with the amyloid fibrils was 15 micrograms/mg fibril weight. The presence of glycosaminoglycans in amyloid may play a part in the incorporation of structurally diverse protein precursors into amyloid fibrils of identical ultrastructure.

Amyloidosis↗
PubMed1988

Differentiation-associated changes in the expression of chondroitin sulfate proteoglycan in induced U-937 cells.

A monoblastic cell line U-937 (clone 4), was induced to differentiate along the monocytoid lineage by 12-O-tetradecanoylphorbol-13-acetate (TPA), retinoic acid (RA), and vitamin D3 (VD3). By immunochemical and morphological criteria the cells were found to differentiate into macrophage-like cells in the presence of all three inducers. The expression of proteoglycans was investigated in control cultures and in cells differentiated in the presence of both TPA, RA, and VD3. The cells were labeled with [35S]sulfate and cell and medium-associated 35S-macromolecules were either solubilized in sodium dodecyl sulfate or subjected to proteolytic digestion. By use of chondroitinase ABC digestions and deaminative cleavage at pH 1.5 it was demonstrated that all cell cultures incorporated [35S]sulfate exclusively into chondroitin sulfate proteoglycan (CSPG). The expression of CSPG was found to decrease with differentiation to 60% in the presence of TPA, 67% in RA, and 40% in VD3 of control cultures on a cellular basis. The CSPG synthesized was consistently recovered from the medium fractions, whereas free glycosaminoglycan (GAG) chains were found in the cell fraction in all the cell cultures. GAG chains from both control and TPA-, RA-, and VD3-induced cultures were found to be exclusively of the chondroitin 4-sulfate type. However, the CSPGs from RA- and VD3-treated cells were found to differ in molecular size from those of control and TPA-induced cultures, as judged by Sepharose CL-6B gel chromatography. This difference in macromolecular properties following the induced differentiation of the monoblastic cells into macrophage-like cells was found to reside in expression of CSPGs (in the presence of RA and VD3) with smaller GAG chains. Control cells and TPA-induced cells synthesized CSPGs with GAG chains of approximate Mr of 30,000, contrasted by approximate Mr of 17,000 and 16,000 in RA- and VD3-induced cells, respectively. Accordingly, all three agents used in this study were found to induce differentiation of the U-937-4 cells and a decrease in the expression of CSPG, but only RA and VD3 were found to influence the structure of the proteoglycans synthesized.

Cell Differentiation↗
PubMed1988

Cell density-dependent expression of chondroitin sulfate proteoglycan in cultured human monocytes.

Monocytes were isolated and established in vitro at different cell densities. The incorporation of [35S]sulfate into macromolecules in monocytes (day 1 in culture) and monocyte-derived macrophages (day 5 in culture) was found to increase with decreasing cell density in approximately the same way in both day 1 and day 5 cell cultures. [35S]Sulfate was found to be incorporated almost exclusively into chondroitin sulfate proteoglycan (CSPG) in both high and low density monocyte and monocyte-derived macrophage cultures. The molecular size of the [35S]CSPGs produced by the high and low cell density cultures were not found to differ as judged by gel chromatography elution patterns. The molecular size and the structure of the glycosaminoglycan chains were found to be almost similar in high and low density day 1 and day 5 cultures. Only a small degree of proteoglycan degradation could be observed in both high and low density cultures. Furthermore, cell density-dependent differences in CSPG biosynthesis could be observed already 2 h after the establishment of the cultures, indicating that a process of "down-regulation" in high density cultures was already in operation. The glycosaminoglycan synthesis in high cell density day 1 cultures could be increased slightly following exposure to 0.5 mM benzyl-beta-D-xyloside, but not to the same level as that observed in untreated low cell density cultures. By contrast, the expression of 35S-macromolecules by cells cultured at high cell density for 5 days could be increased by xyloside treatment almost to the same level as that observed in the low density cultures.

Cell Count↗
PubMed1988

Colonization of the rat liver by syngeneic tumor cells. An experimental approach by in vivo and in situ studies.

Syngeneic colon carcinoma cells and glioma cells were injected into the portal vein of BD IX rats. After various time periods the animals were sacrificed and the livers and lungs were fixed and prepared for histology. Atypical cells were observed in the liver 4 and 7 days after the injection of tumor cells, whereas distinct colonies of both colon carcinoma and glioma cells were demonstrated after 14 days. Lung metastases of both tumor cell types were seen after 14 and 30 days. Furthermore, injection of glioma and carcinoma cells into the tail vein gave detectable lung metastases after 7 and 4 days respectively. Intraperitoneal injection of tumor cells resulted in the accumulation of large tumor masses, particularly in the mesentery. By in situ perfusions of the liver with tumor cells included in the perfusion medium it was possible to establish that all the tumor cells were arrested in the course of 4 min. In contrast, normal rat leukocytes were not trapped in the liver, whereas trypsin-treated leukocytes were, suggesting the importance of trypsin-sensitive structures for binding to hepatic tissue. The binding of both glioma and carcinoma cells to the liver and the ensuing growth of tumor nodules in this organ indicate a lack of specificity on part of the malignant cell types for metastasis to the liver in the rat. Both tumor cell types colonized the first organ encountered after injection.

Animals↗
PubMed1988

Sulfur-containing macromolecules in cultured monocyte-like cells.

The monocytic cell line U-937 was cultured in vitro in the absence or presence of phorbol myristate acetate, and agent known to induce differentiation of these cells along the monocyte/macrophage lineage. The cells were fixed, prepared for, and subjected to transmission scanning electron microscopy. The intracellular structures of the cells were compared with those of mastocytoma cells. The latter cell type, known to produce heparin, was shown to contain numerous electron dense granules; by X-ray micro-analyses shown to contain significant amounts of sulfur. In contrast, neither control nor PMA-treated U-937 cells contained such granules. Both control and PMA-treated U-937 cells were pulsed with 35S-sulfate for 60 min and chased. The amount of 35S-proteoglycan in the medium of both cell cultures was found to increase in a time-dependent manner, suggesting that these products are destined for release and not intracellular storage under in vitro conditions.

Cell Line↗
PubMed1988

Cultivation of mouse macrophages in vitro on different protein substrates.

Macrophages were isolated from the peritoneal cavity of mice and cultured in vitro under serum-free conditions on glass coverslips or glass coverslips coated with either collagen, fibronectin or fibrin. The recovery of greater than 95% pure populations of macrophages was highest on fibronectin and fibrin coats when compared to controls on glass coverslips. The cultivation of macrophages on fibronectin and fibrin coats induced a large degree of cell spreading, normally regarded as a parameter of stimulation in cultured macrophages. However, the ability of macrophages to lyse tumour cells and to release lysosomal enzymes was not found to differ to any considerable extent in cells cultured on the different substrates. Culturing macrophages on protein substrates may be used to study macrophage function in vitro, particularly under serum-free conditions.

Animals↗
PubMed1987

Proteoglycans in normal and neoplastic monocytes.

35S proteoglycans produced by normal and neoplastic (U-937) monocytes after a 20-h pulse with [35S]sulfate in vitro have been isolated and compared. Both cell types produce exclusively chondroitin sulfate proteoglycan (CSPG), which are released into the medium and are not contained within the cells. The neoplastic cell-derived molecules were much larger in molecular size, due to the substitution of galactosaminoglycan chains, with an approximate Mr of 60,000. The corresponding chains in monocyte CSPG had an Mr of approx. 20,000. The latter chains were also found to be more sulfated than their neoplastic counterparts.

Cell Line↗
PubMed1987

Proteoglycan biosynthesis in relation to differentiation of cord blood monocytes in vitro.

Human monocytes were obtained from umbilical cord blood and cultured in vitro. By morphological criteria, the neonatal monocytes developed into macrophage-like cells in the course of 3-5 days in culture. The cells were exposed to [35S]sulphate for 24 h, either from day 0-1 or day 9-10 in vitro. The 35S-labelled macromolecules recovered were mainly associated with the medium fraction (approximately 75%) in both day 1 and day 10 cultures. These secretory macromolecules were demonstrated by the use of chondroitinase ABC-digestions to contain predominantly chondroitin sulphate proteoglycan (CSPG). [35S]galactosaminoglycan chains from day 10 cultures were more highly sulphated than the corresponding day 1 species due to the appearance of (glucuronosyl-4,6-diS-N-acetylgalactosamine) disulphated disaccharide units. The galactosaminoglycan chains in neonatal CSPG were found to increase in Mr during cultivation in vitro; from mean Mr of 20,400 to 30,200 (n = 5) in day 1 and day 10 medium proteoglycans, respectively. The corresponding Mr values for adult monocyte [35S]galactosaminoglycan chains were 21,300 and 22,800. On the basis of the concomitant changes in cellular morphology and glycosaminoglycan structure, it is concluded that neonatal monocytes, like monocytes from adults, differentiate into macrophage-like cells in vitro.

Age Factors↗