Biomedical subjects

K Nilsson

Publications and source records attributed to K Nilsson.

At least 109 records · Page 6Linked to original sources

PubMed1997

Myeloperoxidase mediates cell adhesion via the alpha M beta 2 integrin (Mac-1, CD11b/CD18).

Myeloperoxidase is a leukocyte component able to generate potent microbicidal substances. A homologous invertebrate blood cell protein, peroxinectin, is not only a peroxidase but also a cell adhesion ligand. We demonstrate in this study that human myeloperoxidase also mediates cell adhesion. Both the human myeloid cell line HL-60, when differentiated by treatment with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or retinoic acid, and human blood leukocytes, adhered to myeloperoxidase; however, undifferentiated HL-60 cells showed only minimal adhesion. No cells adhered to horseradish peroxidase, and cell adhesion to myeloperoxidase was not decreased by catalase, thus showing that peroxidase activity, per se, was neither sufficient nor necessary for the adhesion activity. Mannan, which has been reported to inhibit the binding of peroxidases to cells, did not affect adhesion to myeloperoxidase. However, adhesion to myeloperoxidase was inhibited by monoclonal antibodies to alpha M (CD11b) or to beta2 (CD18) integrin subunits, but not by antibodies to alpha L (CD11a), alpha M (CD11c), or to other integrins. Native myeloperoxidase mediated dose-dependent cell adhesion down to relatively low concentrations, and denaturation abolished the adhesion activity. It is evident that myeloperoxidase supports cell adhesion, a function which may be of considerable importance for leukocyte migration and infiltration in inflammatory reactions, that alpha M beta2 integrin (Mac-1 or CD11b/CD18) mediates this adhesion, and that the alphaM beta2 integrin-mediated adhesion to myeloperoxidase is distinct from the previously reported ability of this integrin to bind to certain denatured proteins at high concentrations.

Antibodies, Monoclonal↗

PubMed1997

Concentration-dependent effects of hematopoietic growth factors during in vitro expansion of mouse stem cells and progenitor cells.

The effects of cytokine concentrations on proliferation and differentiation of mouse hematopoietic stem cells and progenitors have been investigated. While high concentrations of IL-1 and IL-3 decreased the recovery of primitive cells, maintenance of committed progenitors appeared insensitive to various concentrations of these cytokines. Expansion of multilineage colony-forming bone marrow cells showed a strong concentration dependence on IL-1 and IL-3. When C.B-17 mice were transplanted with AA4.1+ cells from BALB/c fetal liver, cells maintained in 10-20 units per ml of IL-1, IL-3, and IL-6 were able to rescue 89% of lethally irradiated recipient mice. In contrast, cells maintained in 200-500 units per ml could only rescue 19% of the mice. Apparently too high concentrations of cytokines may favour the induction of differentiation of stem cell populations. An alternative explanation could be the presence of accessory cells producing inhibitory factors or cytokines that induce differentiation of stem cells.

Animals↗

PubMed1997

Tissue and differentiation specific expression on the endogenous retrovirus ERV3 (HERV-R) in normal human tissues and during induced monocytic differentiation in the U-937 cell line.

ERV3 (HERV-R) is a complete, single copy human endogenous retrovirus located on the long arm of chromosome 7. The open reading frame in its envelope gene has been conserved during evolution but the gag and pol genes contain in-frame termination codons. To find a suitable experimental model system for analysis of the functions of the ERV3 genome, an extensive screening study of different normal and neoplastic human tissues was performed. Most tissues express low levels of the ERV3 env mRNA although high expression levels are observed in placenta, sebaceous glands, adrenals, testis, bronchial, epithelium and the monocytic cell line U-937. In U-937 cells the ERV3 env expression varied in a manner related to the differentiation status of the cells; being highest in the terminally differentiated non proliferating cells. U-937 cells can be induced to differentiate from the monoblastic to the mature monocyte/macrophage stage upon stimulation by several substances such as phorbolesters (TPA), Vitamin D3, Retinoic Acid (RA) and combinations of some cytokines. We conclude that the ERV3 locus is expressed in a tissue and differentiation specific way and that the U-937 cell line is a suitable model system to further analyze the proposed functions of ERVs such as immunomodulation, cell fusion and protection against exogenous retroviral infections.

Cell Differentiation↗

PubMed1996

Insulin-like growth factor I is a growth and survival factor in human multiple myeloma cell lines.

Human multiple myeloma (MM) represents a highly aneuploid tumor as shown by cytogenetic studies. This may partly explain the heterogeneity with regard to growth factor requirements demonstrated among MM cells. We have previously reported the expression of insulin-like growth factor I (IGF-I) and IGF-I receptor (IGF-IR) mRNA in some MM cell lines. In this study we investigated the role of IGF-I as a growth and/or survival factor in three MM cell lines: LP-1, EJM, and Karpas 707. We report that all cell lines expressed IGF-I and IGF-IR mRNA and protein. LP-1 and Karpas 707, but not EJM, were stimulated to proliferation in a dose-dependent manner by exogenous IGF-I. An IGF-IR blocking antibody inhibited both the IGF-I-induced and spontaneous growth of LP-1, and Karpas 707, while the EJM cell line was unaffected by the addition of the antibody. In conclusion, our results show that IGF-I can act as a growth factor in human MM, and they suggest that an autocrine IGF-I loop may contribute to the growth and survival in some MM cell lines.

Base Sequence↗

PubMed1996

C3a and C5a are chemotaxins for human mast cells and act through distinct receptors via a pertussis toxin-sensitive signal transduction pathway.

Mast cells are known to accumulate at sites of inflammation, however, the chemotaxins involved are undefined. Since most natural leukocyte secretagogues also induce cell migration, and since the anaphylatoxins C3a and C5a are mast cell secretagogues, we hypothesized that both C3a and C5a are also mast cell chemotaxins. Here we report that C3a and C5a are, in fact, potent chemotaxins for the human mast cell line HMC-1. The optimal concentrations, half-maximal effective concentrations (a measure of agonist potency) and the efficacy (response at the optimal concentration) compared with medium control were, for C3a: 10 nM, 0.5 nM, and 256%, respectively; for C5a: 1 nM, 10 pM and 145%. Chemotaxis of HMC-1 cells to both C3a and C5a was blocked by pertussis toxin, suggesting that Gi-coupled receptors are involved in signal transduction. C3a and C5a also induced transient pertussis toxin-inhibitable increases in [Ca2+]i (ED50 = 1 nM for both) that could be homologously but not heterologously desensitized, suggesting that the receptors for C3a and C5a are distinct. These results make C3a the most effective mast cell chemotaxin identified to date. The chemotactic potency described here for C3a is also 100- to 1000-fold greater than for all of its previously described cellular actions. Direct chemoattraction of mast cells by C3a and C5a may help explain the rapid accumulation of mast cells at sites of inflammation.

Adenosine Triphosphate↗

PubMed1996

Expression of the endogenous retrovirus ERV3 (HERV-R) during induced monocytic differentiation in the U-937 cell line.

ERV3 (HERV-R) is a complete human endogenous retrovirus located on the long arm of chromosome 7. LTR-env-gene-spliced mRNA of 9 and 3.5 Kb is widely expressed in human tissues and cells, but gag-pol mRNA has not been found. Further, the env gp70 gene contains an open reading frame throughout its length and its expression has recently been detected as a full-length protein. The highest expression of ERV3 detected so far is in placenta and the lowest in cytotrophoblasts and choriocarcinoma cell lines. In this report we have studied ERV3 mRNA and protein expression in the human monoblastic cell line U-937 during differentiation into monocytes/macrophages. Differentiation of U-937 cells was induced by 1,25a-dihydroxyvitamin D3 (vitD3), retinoic acid (RA), gamma interferon (IFN-gamma) and phorbol-myristate-acetate (PMA-TPA). The expression of ERV3 env mRNA was found to be differentiation-associated, with high expression detected in the late stages of monocytic development. Using TPA, the expression of ERV3 env was detected as 9- and 3.5-kb transcripts by Northern blotting, as mRNA by in situ hybridization and as a cytoplasmic 65-kDa protein by immunofluorescence and Western blots. Low levels of basal expression were found, with up-regulation of both message and protein at 24 to 48 hr after addition of TPA. Induction with vitD3, IFN-gamma and RA produced higher levels of mRNA at earlier time points. It is concluded that the U-937 cell line represents an excellent model system for further studies to study the relationship between ERV3 expression and cellular differentiation.

Calcitriol↗

PubMed1996

Use of a promoter-trap retrovirus to identify and isolate genes involved in differentiation of a myeloid progenitor cell line in vitro.

Studies of gene regulation during early hematopoiesis and of the regulatory network that controls differentiation and lineage commitment are hampered by difficulties in isolating and growing stem cells and early progenitor cells. These difficulties preclude the application of standard molecular genetic approaches to these problems. As an alternative approach we have introduced a lacZ-containing promoter-trap retrovirus into hematopoietic cells. We used the interleukin-3-dependent mouse myeloid progenitor cell 32D as a model to identify transcriptionally active genes. The frequency of integrations that led to transcription of the lacZ gene was estimated to be 0.5% of all integrations, of which 14% were downregulated on differentiation of 32D cells towards neutrophils. Thus, one in every 1,000 to 2,000 integrations identified a developmentally regulated gene. Cellular DNA sequences upstream of proviral integrations were isolated by inverse polymerase chain reaction. Five were further characterized and we confirmed by RNA expression analysis that they were downregulated on differentiation. Sequence analysis revealed identification of novel genes with sequence similarity to known genes. Considering the high efficiency of retroviral infection, our study shows the feasibility of using promoter-trap vectors to identity and isolate developmentally regulated genes from early hematopoietic progenitors.

Animals↗

PubMed1996

Orthostatic hypotension in organic dementia: relationship between blood pressure, cortical blood flow and symptoms.

Regional cerebral blood flow was measured in 35 patients with organic dementia (Alzheimer's disease, n = 13, vascular dementia, n = 17, frontotemporal dementia, n = 5) and orthostatic hypotension. Measurements were performed during supine rest and during head-up tilt (60 degrees). Despite marked blood pressure falls, few patients had symptoms of orthostatic hypotension. All three dementia groups had a decrease in regional cerebral blood flow in the frontal lobes during head-up tilt, but no change in mean hemispheric flow. All patients had a consistent drop in their systolic blood pressure upon head-up tilt, with a wide variation over time. The findings suggest that orthostatic hypotension needs to be considered, and actively sought for, in organic dementia as many patients may lack the typical symptoms of orthostatic hypotension, despite a marked fall in blood pressure.

Aged↗

PubMed1996

Prevalence of thyroid hormone abnormalities in elderly patients with symptoms of organic brain disease.

Analysis of the serum concentrations of free thyroid hormones (fT3, fT4) and thyrotropin (TSH) in 173 psychogeriatric patients (94 females and 79 males, mean age 79 +/- 8 years) disclosed that the hormone levels were related to sex, psychiatric diagnosis, medication and the presence of nonthyroid illness (NTI). Subnormal concentrations of thyroid hormones and/or TSH were found in 25% of the patients. In addition, fT3 and fT4 concentrations were significantly lower (p < 0.05 and p < 0.001, respectively) in demented males compared with demented females although the levels were within the reference limits. Strongly negative correlations between fT3 and age (p < 0.001), and between fT3 and the sedimentation rate (SR) (p < 0.01) were found in demented but not in non-demented patients. These correlations were most pronounced in (age) or restricted to (SR) demented males. In addition, the correlation between fT3 and Hb was strongly positive (p < 0.001) in demented as well as in nondemented patients, particularly in males. The concentration of fT4 was positively correlated to Hb in demented males (p < 0.001), whereas TSH concentration was positively correlated to Hb in demented females (p < 0.05). The results show that TSH is not sufficient as the sole screening assay for evaluation of possible thyroid dysfunction in psychogeriatric patients. In addition, central (hypothalamic?) hypothyroidism may be present in a substantial amount of psychogeriatric patients, as we found an adequate TSH response to exogenous thyrotropin-releasing hormone (TRH) also in patients with decreased fT3/fT4 and no signs of non thyroid diseases. Furthermore, there was an apparent lack of correlation between thyroid hormone levels and dementia (or subgroups of dementia), even though thyroid hormone abnormalities seemed to be rather common in frontotemporal dementia (38%) and non specified dementia (36%).

Age Distribution↗

PubMed1996

Anti-cancer drug characterisation using a human cell line panel representing defined types of drug resistance.

Differential drug response in a human cell line panel representing defined types of cytotoxic drug resistance was measured using the non-clonogenic fluorometric microculture cytotoxicity assay (FMCA). In total 37 drugs were analysed; eight topoisomerase II inhibitors, eight anti-metabolites, eight alkylating agents, eight tubulin-active agents and five compounds with other or unknown mechanisms of action, including one topoisomerase I inhibitor. Correlation analysis of log IC50 values obtained from the panel showed a high degree of similarity among the drugs with a similar mechanism of action. The mean percentage of mechanistically similar drugs included among the ten highest correlations, when each drug was compared with the remaining data set, was 100%, 92%, 88% and 52% for the topoisomerase II inhibitors, alkylators, tubulinactive agents and anti-metabolites respectively. Classification of drugs into the four categories representing different mechanisms of action using a probabilistic neural network (PNN) analysis resulted in 29 (91%) correct predictions. The results indicate the feasibility of using a limited number of cell lines for prediction of mechanism of action of anti-cancer drugs. The present approach may be well suited for initial classification and evaluation of novel anti-cancer drugs and as a potential tool to guide lead compound optimisation.

Antineoplastic Agents↗

PubMed1996

The fibroblast mitogenic activity released from human basophilic cell line KU812 is separate from tryptase and PDGF expression.

The human leukaemia cell line KU812 has previously been used to study basophil differentiation. In this study the authors analysed the capacity of KU812 to produce the mast cell proteinase tryptase and to synthesize factor(s) mitogenic for fibroblasts. KU812 cells were treated with tetradecanoyl-phorbol-13-acetate (TPA), conditioned medium from the human T-cell line Mo (Mo-CM), or cultured under serum free conditions. After 4 days the cells were analysed for cell growth, differentiation, content of tryptase, and secretion of fibroblast mitogenic activity. Mo-CM and serum starvation increased the expression while TPA treatment down-regulated the expression of Fc epsilon RI-alpha chain. An increase in tryptase content in cell extracts was detected after 4 days of culture in serum-free medium or in the presence of Mo-CM. KU812 conditioned media was found to have a baseline expression of mitogenic activity on normal human foreskin fibroblasts that was increased after serum starvation or after treatment with TPA. Mast cell-derived tryptase has previously been reported to be mitogenic for fibroblasts, but in this study the expression of tryptase did not correlate with the expression of fibroblast mitogenic activity in KU812 cells. Furthermore, affinity-purified lung tryptase did not show any mitogenic activity. Platelet-derived growth factor was also excluded. Although the factor(s) from KU812 cells stimulating fibroblast proliferation have not been identified, our results indicate that basophils may be potential producers of growth factors inducing fibroblast proliferation.

3T3 Cells↗

PubMed1996

Characterization of a human basophil-like cell line (LAMA-84).

LAMA-84, a human leucocytic cell line, which upon establishment was described as having megakaryocytic, erythroid and granulocytic characteristics, was analysed for expression of various differentiation markers. In addition to some of the previously described phenotypic characteristics, this cell line was found to express mRNA for several proteins characteristic for basophilic leucocytes and mast cells. The authors show that LAMA-84 cells express mRNA for the mast cell tryptase, the proteoglycan core protein, carboxypeptidase A and the alpha and beta chains of the high affinity IgE receptor (Fc epsilon RI). The authors examined the potential of LAMA-84 to differentiate in serum-free medium or after DMSO or PMA treatment. Depending on the inducing factor, surface expression of the Fc epsilon RI alpha-chain was increased from 20% to 35-50% of the cells and mRNA levels for tryptase were increased in serum-free medium and after DMSO treatment. LAMA-84 was found to express CD13, CDw17, CD29, CD33, CD40, CD45 and CD117. Furthermore, mRNA for the eosinophil/basophil markers Charcot-Leyden crystal (CLC) protein and the major basic protein (MBP), as well as the erythrocyte differentiation marker alpha-globin, was detected. However, the authors observed only trace amounts of mRNA for another erythroid differentiation marker (glycophorin), trace amounts of the megakaryocytic marker GPIIIa, and no detectable level of GPIb alpha. By comparing the expression pattern of a panel of differentiation markers in LAMA-84, and a second human cell line (KU812) expressing a basophil phenotype, it is evident that these cell lines, which presently are the only two cell lines identified with basophilic characteristics, share a large number of phenotypic characteristics.

Antigens, Surface↗

PubMed1996

Hyperhomocysteinaemia--a common finding in a psychogeriatric population.

Plasma homocysteine concentration is a sensitive marker for cobalamin and folate deficiency. The previously reported high incidence of increased plasma homocysteine in psychogeriatric patients and the association between reduced concentrations of cobalamin, folate and neuropsychiatric symptoms led to the present study on 741 consecutive psychogeriatric patients. The concentrations of plasma homocysteine correlated significantly with blood folate, serum cobalamin and serum creatinine both in demented (n = 295) and in non-demented patients with other psychiatric disorders (n = 215). Plasma homocysteine concentrations were significantly increased in both the demented and the non-demented patients, whereas only the demented patients had lower blood folate and serum creatinine concentrations than 163 control subjects. Almost all of the different diagnostic groups of demented and non-demented patients exhibited significantly increased plasma homocysteine concentrations compared with control subjects. Significantly decreased blood folate concentrations were mainly found in the different diagnosis groups of demented patients. Plasma homocysteine concentrations in both demented and non-demented patients with serum cobalamin and blood folate above the lower 20th percentile of these vitamins in the control subjects were also studied. Despite these vitamin concentrations, both groups of patients still exhibited significantly higher plasma homocysteine concentrations than the control subjects, which may indicate an increased frequency of impaired genetic capacity to metabolize homocysteine in these patients. Patients with either dementia of vascular cause or a history of other occlusive arterial disease had a significantly higher plasma homocysteine concentration than those without a history of vascular disease.

Aged↗

PubMed1996

Stem cell factor-dependent human cord blood derived mast cells express alpha- and beta-tryptase, heparin and chondroitin sulphate.

The present study sought to determine the expression of alpha- and beta-tryptase in in vitro differentiated human cord blood derived mast cells. We also analysed the glycosaminoglycan composition and the phenotype of the cells. The major protease in human mast cells is tryptase, and cDNAs for two different human tryptases have been characterized, the so-called alpha- and beta-tryptase. By reverse transcriptase-polymerase chain reaction (RT-PCR) we could show that stem cell factor (SCF)-dependent cord blood derived mast cells express both alpha- and beta-tryptase. Furthermore, the cells were stained with a monoclonal antibody (mAb) against tryptase, and the tryptase was enzymatically active cleaving the substrate Z-Gly-Pro-Arg- methoxy-2- naphthylamide (MNA). The majority of the cord blood derived mast cells could also be stained with mAbs against chymase, cathepsin G and CD68. They also expressed Kit/SCFR (CD117), CD13, CD29 and CD45 on the cell surface. The proteoglycan-derived polysaccharide composition of the cells was estimated to be 25-35% of heparin origin and 65-75% of chondroitin sulphate origin. Hence, the cord blood derived mast cells exhibit a phenotype in common with the so-called MCTC type of human mast cells.

Base Sequence↗

PubMed1996

Regional skin temperature, heat flow and conductance in preterm neonates nursed in low and in neutral environmental temperature.

The changes of regional dry heat loss and skin temperature in 15 healthy preterm babies, 8 with a gestational age (GA) of 33-36 weeks and 7 with a GA of 28-31 weeks, were studied under controlled conditions at environmental temperatures ranging from 29.5 to 34.0 degrees C. In both groups of babies the skin temperature for all body regions followed the changes in operative temperatures. Regional dry heat losses also closely followed the external temperature gradient. In the 33-36 weeks GA neonates the regional changes in thermal conductance (index of cutaneous blood flow) indicated that only the foot responded to low environmental temperature with vasoconstriction while vasodilatation was indicated for the trunk. In the 28-31 weeks GA neonates similar but not significant changes of thermal conductance were calculated. The limited ability to reduce heat loss by reducing the skin conductance over a major part of the body surface area contributes to the vulnerability to low environmental temperature in preterm neonates.

Body Surface Area↗

PubMed1996

Reproducibility of clinical caries diagnoses on coronal and root surfaces.

Intra- and interexaminer reproducibility of clinical caries diagnoses was studied using 3 experienced dentists, who independently examined 20 patients twice at an interval of 2-6 weeks. The lesions were classified as one of the following four diagnoses: (1) initial active caries, (2) initial inactive caries, (3) manifest active caries, and (4) manifest inactive caries. For the various diagnoses, signs of cavitation, surface structure and discolouration were used. The reproducibility at a patient level was evaluated using intraclass correlation coefficients and at a surface level using kappa statistics. At a patient level, for the total number of lesions, the intraclass coefficients of correlation varied from 0.55 to 0.77. For the individual diagnoses, total manifest caries showed the highest coefficients of correlation, ranging from 0.73 to 0.92. At a tooth surface level, the kappa values varied from 0.29 to 0.61. The most common shift was that from any type of caries diagnosis to a diagnosis of a sound surface. There was little difference between the results for coronal and root caries and between initial and manifest lesions. Nor was there any difference for buccal + lingual surfaces only compared to all surfaces. Judging from the pattern of change in diagnosis between the repeated examinations, the main source of error seemed to be due to the fact that the lesions observed at one examination were overlooked at the other examination.

Adult↗

PubMed1996

Effects of interferons and tumour necrosis factor-alpha on human lung cancer cell lines and the development of an interferon-resistant lung cancer cell line.

Thirteen human lung cancer cell lines, 7 representing small cell lung cancer (SCLC) and 6 different types of non-SCLC, were tested for sensitivity to tumour necrosis factor alpha (TNF-alpha) and interferon alpha and gamma (IFN-alpha and gamma) using an automated fluorometric microculture cytotoxicity assay (FMCA). One SCLC line (H-82) was found to be sensitive to IFN-alpha in short-term (72 h) culture, whereas after prolonged (5 days) culture two additional SCLC cell lines responded to IFN-gamma. TNF-alpha inhibited the growth of one large cell carcinoma cell line (H-157), whereas all SCLC lines were found to be insensitive. The combination of IFN-gamma and TNF-alpha produced no further response compared with the single agents used alone. By continuous cultivation of the IFN-alpha-sensitive cell line H-82 in the presence of increasing concentrations of IFN-alpha, an IFN-alpha-resistant subline (H-82) was established. This line displayed a high degree of resistance ( > 100 fold) to IFN-alpha and cross-resistance to IFN-gamma. There was no alteration in the number of IFN binding sites, in the growth rate, the expression of selected surface markers for SCLC or the expression of multidrug resistance markers in the H-82R subline compared with the parental H-82 cell line. The results demonstrate a heterogeneous response of SCLC cell lines to IFN-alpha and gamma and TNF-alpha with only a minority of the cell lines responding to these agents by growth inhibition. The IFN-alpha and gamma H-82R subline may serve as a valuable tool in future studies on the mechanisms of IFN antitumour activity.

Antigens, Neoplasm↗

PubMed1996

Stem cell factor, but not flt3 ligand, induces differentiation and activation of human mast cells.

We have examined the effect of human ligand for the flt3/flk2 tyrosine kinase receptor on the differentiation of human mast cells in suspension cultures. We also explored the effect of flt3 ligand (FL) on the human mast cell line HMC-1 and mRNA expression of flt3/flk2 on in vitro developed human mast cells and HMC-1. The growth of cord blood mononuclear cells in suspension cultures was increased when cells were cultured in the presence of FL compared with cells cultured in the presence of stem cell factor (SCF). When SCF and FL were combined, the total cell growth was increased further. Our data show that Fl by itself neither induced differentiation of mast cells nor acted in the SCF-dependent differentiation of human cord blood-derived mast cells (CBMC). Furthermore, no effects of FL were found on the proliferation of HMC-1 cells or the induction of early-immediate response genes in HMC-1 cells. In addition, neither HMC-1 cells nor CBMC expressed mRNA for flt3. As has been shown before, SCF and FL have little biological effect on their own but synergize well with a number of other hematopoietic growth factors. This study shows that a major difference between FL and SCF is that only SCF affects the differentiation and activation of mast cells.

Base Sequence↗