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Biomedical subjects

K Nilsson

Publications and source records attributed to K Nilsson.

At least 127 records · Page 7Linked to original sources
PubMed1996

Vitamin D3- and retinoic acid-induced monocytic differentiation: interactions between the endogenous vitamin D3 receptor, retinoic acid receptors, and retinoid X receptors in U-937 cells.

Retinoic acid (RA) and 1,25 alpha-dihydroxycholecalciferol (VitD3) are potent regulators of hematopoletic differentiation. Yet, little is known as to how the RA and VitD3 receptor network operates in hematopoietic cells, and whether receptor interactions can explain the interplay between the RA- and VitD3-signaling pathways during differentiation. Therefore, we analyzed the expression, DNA binding, and transcriptional activity of the endogenous RA and VitD3 receptors [retinoic acid receptors (RARs), retinoid X receptors (RXRs), and VitD3 receptor (VDR)] in the U-937 cell line, in which RA and VitD3 induce distinct monocytic differentiation pathways. VitD3 induction resulted in the formation of VDR/RXR DNA-binding complexes on both VitD3 response elements and RA response elements (RAREs). However, transcriptional activation was only observed from a VitD3 response element-driven reporter construct. Several DNA-binding complexes were detected on RAREs in undifferentiated cells. Stimulation by RA resulted in increased RAR beta/RXR DNA binding, activated RARE-dependent transcription, and increased expression of RAR-beta. Concomitant stimulation by VitD3 inhibited the RA-stimulated formation of RAR beta/RXR heterodimers, favoring VDR/RXR binding to the RARE. Also, VitD3 inhibited the expression of CD23 and CD49f, characteristic markers of retinoid-induced U-937 cell differentiation. In contrast, neither the RA-stimulated, RARE-mediated transcription nor the induced RAR-beta expression was suppressed by VitD3, suggesting that VitD3 selectively inhibited the retinoid-induced differentiation program but not the RARE-mediated signal. These results demonstrate a complex role for VitD3 in modifying the retinoid differentiation pathway and may have implications for differentiation-inducing therapy of hematopoietic tumors.

Cell Differentiation↗
PubMed1995

The hematopoietic transcription factor PU.1 is downregulated in human multiple myeloma cell lines.

PU.1 is a hematopoietic transcription factor belonging to the Ets-family. It is identical to the Spi-1 oncogene, which is implicated in spleen focus-forming virus-induced murine erythroleukemias. PU.1 seems to be required for early development of multiple hematopoietic lineages, but its expression in mature cells is preferentially observed in cells of the B-cell-and monocyte/macrophage-differentiation lineage. It binds the so-called Pu box, an important tissue-specific regulatory DNA element present in a number of genes expressed in these cell lineages. We have analyzed the expression and activity of PU.1 during human B-cell development using a panel of B-cell lines representing different stages of maturation, from early precursors to differentiated plasma cells. PU.1 mRNA expression and PU.1 DNA binding activity, as measured by Northern blot analysis and electrophoretic mobility shift assay, respectively, were evident in cell lines representing pro-B, pre-B, and mature B cells. We could also show Pu box-dependent transactivation of a reporter gene in transient transfections in these cell lines. In contrast, in a number of multiple myeloma cell lines, representing differentiated, plasma cell-like B cells, PU.1 DNA binding activity, mRNA expression, and Pu box-dependent transactivation were absent or detectable at a very low level. In lymphoblastoid cell lines, which exemplify an intermediate stage of B-cell differentiation, a reduced expression and activity were observed. The findings in the human multiple myeloma cell lines represent the first examples of B cells with downregulated PU.1 expression and apparently contradict observations in the murine system in which PU.1 is expressed and active in plasmacytoma cell lines. At present, it is unclear whether the lack of PU.1 expression and activity in human multiple myeloma cell lines represents a malignancy-associated defect in these cells or exemplifies a normal developmental regulation in terminally differentiated B cells.

B-Lymphocytes↗
PubMed1995

Effects of interleukin (IL)-13 on immediate-early response gene expression, phenotype and differentiation of human mast cells. Comparison with IL-4.

The recently cloned interleukin 13 (IL-13) shares most investigated biological activities on B lymphocytes and monocytes with IL-4. In this study we investigated the potential role of IL-13 in regulating human mast cell activities. The effects of IL-13 on the expression of an immediate-early response gene (c-fos), proliferation, expression of mast cell-associated cell surface antigen (CD54 and Kit), and in vitro differentiation of human mast cells, were investigated. We compared the effect of IL-13 with that of IL-4. Both IL-13 and IL-4 induced expression of c-fos in cells from the human mast cell line HMC-1. This indicates that mast cells express functional receptors for IL-13. IL-13 and IL-4 decreased the proliferation rate of HMC-1 cells. However, IL-13 was less potent than IL-4. Human mast cells constitutively express the adhesion molecule ICAM-1 (CD54) and the receptor for stem cell factor (Kit) (CD117). The expression of CD54 was increased after treatment with IL-13 or IL-4, whereas the expression of Kit was decreased. Also in this action IL-4 was more potent than IL-13. By culturing mononuclear cells from cord blood in the presence of stem cell factor there is a differentiation of tryptase-positive mast cells in the cultures. This process was inhibited when IL-4 was present. In contrast, IL-13 did not affect the expression of tryptase during differentiation of stem cell factor dependent cord blood-derived mast cells. Taken together, these findings indicate that IL-13 has regulatory effects on human mast cells. The effect overlaps with but is also different from that of IL-4.

Blotting, Northern↗
PubMed1995

The vaginal epithelium in the postmenopause--cytology, histology and pH as methods of assessment.

In the study of postmenopausal vaginal oestrogen deficiency, an objective assessment of the vaginal epithelium is necessary. The present study was undertaken to evaluate different methods for assessing the vaginal epithelium, during atrophic and mature conditions. The vaginal epithelium was assessed by clinical examination, pH and vaginal cytology, including morphometric analysis, before and after oestrogen treatment. Biopsies of the vaginal wall were studied using descriptive histology and immunohistochemistry methods. The antigen Ki-67, a sensitive marker of cell proliferation, was detected using the monoclonal antibody MIB1. When comparing pre- and post-treatment values from the methods, a shift towards mature values was observed, but the magnitude of the shift differed to a considerable extent. Vaginal cytology, expressed as mean maturation index (MI) shifted significantly from 94/6/0 to 0/65/35. Likewise, mean pH was significantly shifted from 6.2 to mean 4.5. The increased presence of Ki-67 positive cells could be demonstrated after oestrogen treatment, but the range of data was wide, which was also found for the thickness of the epithelium and the number of cell layers. For objective assessment of the vaginal epithelium maturation index and pH can be recommended.

Atrophy↗
PubMed1995

Low-dose 17 beta-oestradiol during maintenance therapy--a pharmacokinetic and pharmacodynamic study.

The vaginal absorption of oestradiol was studied during maintenance therapy with low-dose oestradiol. Six women with severe vaginal atrophy due to oestrogen deficiency were treated with a vaginal tablet containing 25 micrograms 17 beta-oestradiol. Initially, a daily dose was given for 2 weeks, followed by maintenance therapy with twice weekly treatment for another 10 weeks. The plasma concentrations of unconjugated oestrone and oestradiol were measured before oestrogen treatment was started at the beginning of the study. After 3 months of treatment frequent plasma sampling over a period of 24 h was performed. Gonadotrophins, vaginal and urethral cytology, clinical findings and subjective symptoms were assessed at the beginning and end of the study. Plasma concentrations of unconjugated oestradiol were at all times within the limits of postmenopausal values, but showed a slight but not statistically significant elevation after 3 months compared to pretreatment values. Plasma concentrations of unconjugated oestrone were in the low postmenopausal range throughout the study. LH levels were unaffected during the study, while FSH was somewhat lowered, but still well within the postmenopausal range. Vaginal and urethral cytology showed maturation with almost complete disappearance of parabasal cells. Clinical and subjective improvement was statistically significant during the treatment period.

Administration, Intravaginal↗
PubMed1995

A CD4+ T cell line-secreted factor, growth promoting for normal and leukemic B cells, identified as thioredoxin.

In this study, a B cell growth stimulatory factor, constitutively secreted by a human CD4+ T cell hybridoma clone, MP6, has been purified and characterized. Serum-free 24 h culture media from MP6 cells were collected, concentrated by ultrafiltration and separated by gel chromatography. Fractions were analyzed for stimulatory activity using [3H]thymidine incorporation in normal and leukemic (B-CLL) B cells as target cells. Activity was present in a 12 kDa protein peak. Upon storage this lost activity indicating that the factor was sensitive to air oxidation, a well-known property of mammalian thioredoxins (Trxs). Treatment of the inactive fraction with dithiothreitol restored full activity. When culture medium was analyzed with a radioimmunoassay for human placenta Trx, the MP6 clone was shown to release 30-50 ng/ml per million cells during 24 h. The B cell stimulatory activity of the MP6 medium was removed by Sepharose-bound anti-human placenta Trx IgG and activity was recovered by elution from the antibodies. Furthermore, MP6 medium showed Trx activity with NADPH and Trx reductase using an insulin disulfide reduction assay. Starting from 5 l of serum-free MP6 conditioned medium, the Trx was purified approximately 100,000-fold. After gel electrophoresis banding, the material was analyzed by peptide sequencing and a full length sequence of an 104 amino acid long protein was obtained. This Trx sequence was identical to the previously published sequence of human Trx from HTLV-1 transformed T cells, adult T cell leukemia-derived factor/Trx.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Cytotoxic effect of calcein acetoxymethyl ester on human tumor cell lines: drug delivery by intracellular trapping.

Calcein acetoxymethyl ester (calcein/AM) and some related cellular dyes with a cytoplasmic distribution were investigated with respect to cellular hydrolysis, accumulation, efflux and cytotoxicity in a panel of established human cell lines, including multidrug resistant (MDR) phenotypes. At 0.1-1 micrograms/ml, calcein/AM was highly cytotoxic against several cell lines, even after short-term exposure (30 min). Calcein/AM induced no immediate loss (3 h) of membrane integrity and the drug was more active against low compared with high density plated cells. In cell lines with the MDR phenotype and in the renal carcinoma cell line ACHN, the drug was considerably less active. Non-esterified calcein had no effect and calcein/AM was significantly more potent than other structurally related fluorescein analogs and AM esters tested. Although MDR cell lines showed a decreased cellular hydrolysis and accumulation of the dye, there was no strict relationship between cytoplasmic calcein exposure and cytotoxic activity. The rate of efflux was low in the two most sensitive cell lines, the human lymphoma U-937-GTB and its vincristine (vcr) resistant subline U-937/vcr10, while the remaining cell lines showed similar biphasic efflux patterns, including cell lines of the MDR phenotype. The results show that calcein/AM has cytotoxic activity against human tumor cell lines at low concentrations. The effect appears dependent on the intracellular trapping of the drug, although the specific cellular target remains unknown. Due to its cytotoxic efficacy and unique principle of cellular drug delivery, further investigation of calcein/AM and related compounds as potentially new anticancer agents seems warranted.

Antineoplastic Agents↗
PubMed1995

Constitutive and inducible cytokine mRNA expression in the human mast cell line HMC-1.

The discovery that mast cells are a potential source of cytokines has suggested new ways in which mast cells can act in immunological and inflammatory responses. In this study we have used the HMC-1 cell line as a model for human mast cells to study the constitutive and inducible mRNA expression of interleukins, colony-stimulating factors, interferons, tumour necrosis factors alpha and beta, tumour growth factor beta and platelet-derived growth factor A and B. We found that HMC-1 cells constitutively expressed mRNA for TNF-alpha and TGF-beta, and a low level of M-CSF. After treatment with the phorbol ester TPA or the calcium ionophore ionomycin expression of several cytokines, i.e. IL-1 beta, IL-3, IL-6, GM-CSF, TNF-beta and PDGF-A, could be detected. Both TPA and ionomycin induced the same set of cytokines, but the effect of TPA was more prominent. The relative induction was calculated to be 70X for IL-1 beta and IL-3, 30X for GM-CSF and PDGF-A and 3 - 10X for IL-6, M-CSF and TNF-beta. This study shows that human mast cells have the capacity to express not only cytokines mediating an immune response but also cytokines affecting other cell types, e.g. fibroblasts and endothelial cells, involved in later steps of the inflammatory response.

Cell Line↗
PubMed1995

Demonstration of specific high-affinity Fc epsilon-receptors on the human basophil-like leukemia cell line KU812 by flow cytometry.

The specificity of IgE binding to a human basophil-like cell line (KU812) was studied by flow cytometry. Four IgE myeloma proteins, representing both light-chain types, one chimeric IgE protein, and polyclonal serum IgE blocked the direct binding of FITC-labeled IgE(DES) myeloma protein to KU812 cells in a dose-dependent and nearly equimolar way. Although not as efficiently as human IgE (from five to eight times less on a molar basis), both rat and mouse IgE blocked IgE(DES)-FITC binding to KU812 cells. In sharp contrast, all four human IgG subclasses, both IgA subclasses, and IgM myeloma proteins, as well as monomeric and heat-aggregated polyclonal human IgG, were unable to block significantly IgE(DES)-FITC binding to KU812 cells (< 0.5% on a molar basis). The cytophilic epitope on IgE was heat-susceptible (56 degrees C, 2 h), lost after reduction alkylation, and resident in the papain-derived Fc epsilon-fragment, but not in the papain-derived Fab epsilon- and Fc'epsilon-fragments nor in the pepsin-derived F(ab')2 epsilon- and Fc"epsilon-fragments. Washing and displacement experiments indicated that a major part of IgE reacted with high affinity to KU812 cells. The results indicate that the binding of IgE to KU812 cells is highly specific and involves the classical high-affinity Fc epsilon RI-receptor. Although the density of receptors is low, this human cell line offers a unique model to study IgE/Fc epsilon RI interactions.

Animals↗
PubMed1995

Evaluation of methods for measurement of regional skin temperature and heat flow in neonates.

A reliable method for measurement of regional heat loss is a prerequisite for studies of heat loss in the neonate with different clothing and under varying environmental conditions. In the present study we evaluated methods for measuring regional skin temperature and regional dry heat loss in neonates, and specifically the influence of contact sensors applied to the skin surface. A modified incubator with controlled climate conditions was used as the climate chamber. The operative temperature was measured continuously with a black globe thermometer. Skin temperature was recorded with small-mass contact sensors and their influence on skin temperature was verified by simultaneous measurement with an infrared camera. The correlation was 0.99 and 1 SD within 0.3 degree C from the line of identity. The influence of the regional heat flow meter on skin temperature was also checked with an infrared camera and was found to be neglible.

Body Temperature Regulation↗
PubMed1995

Measurement of skin temperature and heat flow from skin in term newborn babies.

Regional heat loss and skin temperature changes in 25 healthy, full-term infants were studied under controlled conditions at environmental temperatures of 28-32 degrees C. Skin temperatures for all body regions followed changes in operative temperatures. Regional dry heat losses closely followed the external temperature gradient (difference between skin and operative temperature). The technique allows measurement of regional dry heat loss from the newborn skin exposed to different environmental conditions for different body surface areas. Thermal conductance, as an index of cutaneous blood flow, was calculated in a subgroup of 8 of the 25 babies by decreasing the operative temperature by 3-4 degrees C from the assumed thermoneutal zone. Thermal conductance indicated that only the foot responded to lower temperatures with vasoconstriction. Blood flow index of the chest region increased in all babies at lower temperatures.

Body Temperature Regulation↗
PubMed1995

CD49f (alpha 6 integrin) and CD66a (BGP) are specifically induced by retinoids during human monocytic differentiation.

Retinoic acid (RA) and 1,25(OH)2-cholecalciferol (VitD3) are potent regulators of normal and malignant myeloid cells. In the human monoblast cell line U-937 they induce terminal differentiation, and the resulting phenotypes display both common and distinct, inducer-specific, properties. This paper shows that in U-937 cells the two retinoids, all-trans and 9-cis RA, induced the expression of CD49f (alpha 6 integrin subunit) and CD66a (biliary glycoprotein, BGP) mRNA and protein. In contrast, expression of CD49f and CD66a was not found in untreated or VitD3-induced cells. Cytokine-induced modulation of CD49f and CD66a expression was restricted to the retinoid-induced U-937 cells. The retinoid specific induction of CD49f and CD66a was confirmed in the related monoblastic cell line THP-1. Human blood monocytes and the monocytic cell line Mono Mac 6 responded poorly to RA, with respect to the regulation of CD49f and CD66a expression, indicating that early monocytic precursors were targets for the retinoid-specific regulation. Thus, the expression of CD49f and CD66a is developmentally regulated and specifically induced by all-trans and 9-cis Ra in human monocytic cells.

Antigens, CD↗
PubMed1994

Stem cell factor is a chemotactic factor for human mast cells.

The mast cell is one of the major effector cells in inflammatory reactions and can be found in most tissues throughout the body. During inflammation, an increase in the number of mast cells can be seen, e.g., in the intraepithelial cell layer after a provoked allergic reaction. Such accumulation probably requires directed migration of mature mast cells or their precursors. To study the migration of human mast cells we used as a model the human mast cell line, HMC-1, and stem cell factor-dependent (also referred to as mast cell growth factor or Kit ligand) cord blood-derived mast cells. The results show that stem cell factor is a potent chemotactic factor for human mast cells in vitro. The chemotactic response to SCF was found to be dose dependent, reaching a maximum at 50 ng/ml. The activity of SCF could be blocked by anti-SCF Abs. We also tested the effect of different intercrines, i.e., IL-8, MIP-1 alpha, MIP-1 beta, RANTES, and MCAF (also referred to as monocyte chemotactic protein 1), on human mast cell migration. Only RANTES was chemotactic for in vitro-developed mast cells. None of the tested intercrines induced migration of HMC-1 cells. For migration, the mast cells were dependent on binding to an extracellular matrix protein. Thus, coating of the filters with fibronectin was required, whereas collagen or laminin did not promote migration. Adhesion of HMC-1 cells to fibronectin could also be shown in an adhesion assay. In addition, expression of receptors for fibronectin could be detected on the surface of the mast cells. These results show that SCF is not only a growth and differentiation factor for human mast cells in vitro but also a potent chemoattractant for such cells.

Cell Adhesion Molecules↗
PubMed1994

Development of vincristine resistance and increased sensitivity to cyclosporin A and verapamil in the human U-937 lymphoma cell line without overexpression of the 170-kDa P-glycoprotein.

A vincristine (Vcr)-resistant subline of the human histiocytic lymphoma cell line U-937 (U-937-vcr) has been established and characterized with respect to its phenotypic features, including growth rate, surface marker expression and ability to respond to differentiation-inducing agents. The sensitivity of U-937-vcr cells to the direct cytotoxicity of cyclosporin A (CsA) and verapamil (Ver), and the capacity of these drugs to modify Vcr resistance, were also examined. The U-937-vcr cells exhibited a more than 200-fold resistance to Vcr, and cross-resistance to vinorelbin and taxol. Also, there was a slight cross-resistance to colchicine, doxorubicin and VP16. However, the response of U-937-vcr to CsA or Ver alone was substantially altered, with a marked decrease in their respective IC50s. The U-937-vcr cells did not show increased levels of pgp 170. We conclude that the development of Vcr resistance was not associated with a change in the major phenotypic properties of the U-937 cell line, and that resistance modifier hypersensitivity was not associated with increase in pgp 170 expression.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Tropism for primary monocytes and for monocytoid cell lines are separate features of HIV-1 variants.

We have analyzed the phenotype of five human monocytoid cell lines (U-937, THP-1, RC.2A, Mono Mac 6, and DD) and their capacity to support replication of HIV-1 strains with known tropism for T lymphocytes and mononuclear phagocytes. HIV-1 Ba-L, a prototype monocytotropic HIV-1 strain, was unable to establish continuous replication in any of the cell lines used. In contrast, the lymphotropic strain IIIB could replicate in all CD4-positive cell lines. We conclude that the capacity of HIV-1 isolates to replicate in established human monocytoid malignant cells does not correlate with the tropism of the virus for primary mononuclear phagocytes. Since monocytoid cell lines do not distinguish HIV-1 variants tropic for mononuclear phagocytes, we suggest the use of primary cells for studies of HIV-1 tropism.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Bead-to-bead transfer of Chinese hamster ovary cells using macroporous microcarriers.

Chinese hamster ovary cells (CHO-K1) were cultivated in macroporous gelatin microcarriers (CultiSpher G and CultiSpher S) in spinner flasks and a 51 bioreactor. Near-to-confluent cultures were harvested by bead-to-bead transfer where intact microcarriers with cells were transferred from a spinner flask to another spinner flask or to the bioreactor with naked microcarrier beads. Successful bead-to-bead transfer was achieved in various split ratios. The duration of attachment seemed to be important where the direct contact of beads to each other can be achieved by intermittent stirring. Repeated transfers were performed and at least four transfers in spinner flasks were achieved. Two variations of bead-to-bead transfer were performed in the 51 bioreactor either by seeding the bioreactor with near-to-confluent beads cultivated in spinner flasks or in situ transfer by adding fresh beads to the bioreactor. As in the spinner case, attachment was achieved by intermittent stirring where donor beads were in close proximity to the acceptor beads. Again successful transfers were obtained as evidenced by the good growth on acceptor beads where cell yields were in the range of 3100-4500 cells/bead. The results suggest that bead-to-bead transfer of CHO-K1 cells can be easily performed and do provide an alternative route to applications where dissolution techniques may not offer an efficient solution.

Animals↗
PubMed1994

Interleukin-1 beta induces cyclic AMP formation in isolated human osteoblasts: a signalling mechanism that is not related to enhanced prostaglandin formation.

Interleukin-1 (IL-1) is a potent stimulator of bone resorption. Induction of osteoclastic bone resorption by various endocrine or paracrine factors is mediated via the osteoblasts. We have therefore investigated the effects of IL-1 beta on cell signalling in isolated human osteoblasts. Special interest was focused on prostaglandin synthesis, since indomethacin, an inhibitor of prostaglandin synthesis, partly inhibits IL-1-induced bone resorption. IL-1 beta, at and above 0.3 pM, dose dependently stimulated PGE2 formation in isolated human osteoblasts, with half maximal stimulation, EC50, at 3 pM. Treatment with the calcium ionophore A23187 (1 microM), or with forskolin (30 microM), also stimulated PGE2 formation in human osteoblasts. The time-course for IL-1 beta-induced PGE2 formation was similar to that of forskolin, with a significant increase in the formation of PGE2 seen after 1 h. In contrast, A23187-induced PGE2 formation was seen within minutes. IL-1 beta stimulated the accumulation of cyclic AMP in isolated human osteoblasts incubated for 15 min. This increase in cyclic AMP formation was not secondary to PGE2 formation since it was not blocked by the addition of indomethacin (1 microM). Pretreatment with the phosphodiesterase inhibitor IBMX did not augment IL-1 beta-induced PGE2 formation, nor did the protein kinase A inhibitor Rp-cAMPs inhibit IL-1 beta-induced PGE2 formation, suggesting that cyclic AMP does not mediate the stimulatory effect of IL-1 on PGE2 formation. We conclude that IL-1 beta enhances the formation of cyclic AMP as well as PGE2 in primary cultures of isolated human osteoblasts. The IL-1 beta-induced cyclic AMP formation is, however, not related to the enhanced prostaglandin formation. The findings implicate that both cyclic AMP- and PGE2-formation in osteoblasts might be involved as independent mediators of IL-1 beta-induced bone resorption.

1-Methyl-3-isobutylxanthine↗