Search PubMed⌕ Search

Biomedical subjects

G Nilsson

Publications and source records attributed to G Nilsson.

At least 127 records · Page 7Linked to original sources
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

Influence of intense sound stimuli on skin microcirculation.

Sound influences not only the organ of hearing but also other systems including the circulation. The purpose of the present study was to investigate the effect of strong sound on the skin microcirculation of the palmar area of the hand and of the plantar area of the foot, which are areas of dense microvasculature and rich sympathetic innervation. The laser Doppler technique was used for measuring cutaneous red cell flux (RCF). Eighteen normal subjects were studied. The results indicate that a pure tone sound of 1500 Hz, with an intensity of 100 dBA and duration 5 s, applied by earphones caused a significant decrease in RCF in 14 out of 18 subjects in the finger but not in the foot skin. A higher intensity (110 dBA) tone caused a stronger decrease of RCF in the finger. The latency and the duration of the reaction showed a dependence on the intensity of the sound, i.e. the reaction to the stronger stimulus was of shorter latency (p < 0.01) and longer duration (p < 0.05). The duration of the reaction did not show significant change when a longer stimulus of 30 s was applied. Repetitive stimuli evoked habituation (p < 0.05).

Acoustic Stimulation↗
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

Laser-Doppler perfusion imaging of microvascular blood flow in rabbit tenuissimus muscle.

To evaluate a newly developed high-resolution laser-Doppler perfusion imager (HR-LDPI) for analysis of local tissue perfusion, blood flow measurements in the rabbit tenuissimus muscle were carried out in combination with intravital microscopic observation. The principle of the LDPI method is based on a low-power laser beam scan of the exposed tissue from which a two-dimensional color-coded perfusion map is created through computerized signal analysis. The perfusion of the tenuissimus muscle prepared for microscopic observation was analyzed in a 5 mm x 8 mm area as the muscle was exposed to atmospheric oxygen tension (Po2; 20 kPa), a low Po2 (approximately 3 kPa), and after vasodilatation induced by topical application of prostaglandin E2 (PGE2). In selected areas free from larger vessels, a significantly lower perfusion average reading was demonstrated under high Po2 conditions compared with low Po2 conditions (P < 0.05, n = 5 animals), and application of PGE2 gave rise to an average reading significantly higher than that at low Po2 (P < 0.01, n = 6 animals). The results were in good agreement with the flow changes observed microscopically, and the architecture of the microvascular network, as depicted by in vivo micrographs, was clearly recognizable in the perfusion images. In conclusion, blood flow changes in the rabbit tenuissimus muscle induced by various stimuli were quantitated with the HR-LDPI method and could be spatially resolved in great detail, illustrating the potential of using HR-LDPI for analysis of local blood flow and to reveal spatial perfusion heterogeneity in tissues.

Animals↗
PubMed1995

Ki-67 immunostaining of endometrial biopsies with special reference to hormone replacement therapy.

BACKGROUND: The purpose of this investigation was to evaluate the Ki-67 immunostaining method on formalin-fixed, paraffin-embedded endometrium and to use the method on endometrial biopsies from 30 postmenopausal women treated with 2 mg estradiol and different doses of natural micronized progesterone (50, 100 or 200 mg). METHODS: Two technicians prepared the immunostaining of slides from each of 12 endometrial specimens and 3 different observers estimated the Ki-67 immunostaining. One observer estimated all the slides 3 times on different occasions. The percentage of immunopositive nuclei in glandular epithelium was evaluated. RESULTS: The dominating component of variation for this method was between observers, with a median standard deviation of 20%. A total median variation including all components rendered a standard deviation of 23%. No significant effects of different technicians, preparations, or from the same observer on different occasions were found. In the major part of the biopsies from women on hormone replacement therapy (HRT), only 0-10% of the glandular epithelium was Ki-67 stained. CONCLUSION: Ki-67 immunostaining is an adequate technique to use when evaluating the effects of HRT on the endometrium. The main source of variation is between observers and not the technique of preparing the slides.

Biopsy↗
PubMed1995

Roles of energy status, KATP channels and channel arrest in fish brain K+ gradient dissipation during anoxia

The crucian carp (Carassius carassius L.) is one of the most anoxia-tolerant vertebrates known, being able to maintain ion homeostasis in its brain for many hours of anoxia. This study aims to clarify the importance of glycolysis during anoxia and also to investigate whether the extreme tolerance to anoxia could be due to down-regulation of K+ permeability ('channel arrest') and/or activation of ATP-sensitive K+ (KATP) channels. The latter was also tested in rainbow trout (Oncorhynchus mykiss). The results suggest that, during anoxia, the crucian carp brain is completely dependent on glycolysis, since blocking glycolysis with iodoacetic acid (IAA) rapidly caused an increase in [K+]o that coincided with a drastic drop in ATP level and energy charge. Testing the channel arrest hypothesis by measuring the K+ efflux rate after Na+/K+-ATPase had been blocked by ouabain revealed no change in K+ permeability in crucian carp brain in response to anoxia. Furthermore, superfusing the brain of anoxic crucian carp with the KATP channel blocker glibenclamide did not alter the efflux rate of K+ after glycolysis had been inhibited with IAA. Glibenclamide had no effect on K+ efflux rate in rainbow trout brain during anoxia.

Journal Article↗
PubMed1995

Effects of anoxia on energy metabolism in crucian carp brain slices studied with microcalorimetry

Crucian carp (Carassius carassius L.) is an exceptionally anoxia-tolerant vertebrate. To determine whether isolated crucian carp brain tissue survives anoxia and whether it displays anoxic metabolic depression, heat production (using microcalorimetry), lactate production, ethanol production and the maintenance of ATP, ADP and AMP levels and energy charge were measured in telencephalic brain slices during anoxia. In response to anoxia, heat output decreased by 37 %, corresponding to a 31 % fall in ATP turnover rate. Adenylate phosphates and energy charge were well maintained and no ethanol was produced during anoxia. It is concluded that crucian carp brain tissue has an intrinsic capacity to tolerate anoxia and that it responds to anoxia by depressing metabolic rate and elevating the glycolytic rate, thereby maintaining ATP levels.

Journal Article↗
PubMed1995

Extensive erythrocyte deformation in fish gills observed by in vivo microscopy: apparent adaptations for enhancing oxygen uptake

The secondary lamellae of the gills are the primary sites of oxygen uptake in fish. We have used epi-illumination microscopy in vivo to observe the microcirculation directly in secondary lamellae of rainbow trout (Oncorhynchus mykiss) and roach (Rutilus rutilus). Our observations point at previously unrecognised factors in fish respiratory physiology. Erythrocytes passing through secondary lamellae became greatly deformed. We propose that this deformation plays a role in oxygen uptake by diminishing the diffusion boundary layer (adhesion layer) of fluid around the erythrocyte and possibly also by mixing intracellular haemoglobin molecules. Moreover, the erythrocytes were apparently slowed down and forced to travel over an extended path to pass through the lamella, making it tempting to speculate that plasma passes more readily than erythrocytes through the lamella, resulting in a local elevation of the haematocrit.

Journal Article↗
PubMed1995

Dexamethasone inhibits the development of mast cells from dispersed human fetal liver cells cultured in the presence of recombinant human stem cell factor.

Human fetal liver cells cultured in the presence of recombinant human stem cell factor (rhuSCF) give rise to highly purified mast cell populations. This study examined the effect of steroid hormones on mast cell differentiation. Dispersed fetal liver cells cultured in the presence of rhuSCF at 50 ng/ml and in the presence or absence of various steroid hormones for 4 weeks, were analysed for the presence of mast cells by metachromatic staining with toluidine blue, by immunohistochemistry with a monoclonal antibody against tryptase, and by immunofluorescent flow cytometry with a monoclonal antibody against Kit. Dexamethasone added to the cultures at day 0 resulted in a dose-dependent inhibition of rhuSCF-induced mast cell differentiation with > 85% inhibition seen at a dose of 10(-6) M. A similar effect was seen with hydrocortisone, but not with oestradiol or progesterone. The addition of dexamethasone resulted in decreased DNA synthesis in 14-day-old cultured cells, as assessed by incorporation of bromodeoxyuridine. Addition of dexamethasone to 3-week-old SCF-dependent fetal liver mast cells had no significant effect on mast cell survival. Removal of dexamethasone after 3 weeks of culture with SCF did not result in mast cell development. Thus, dexamethasone inhibits SCF-induced development of mast cells from fetal liver cells, but shows no appreciable effect on developed mast cells.

Cell Differentiation↗
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

Interleukin-4 inhibits the expression of Kit and tryptase during stem cell factor-dependent development of human mast cells from fetal liver cells.

Although interleukin-4 (IL-4) in mice is known to augment the proliferation of mast cells and to modulate the expression of certain mast cell protease transcripts, its effect on human mast cells is less well understood. The current study examined the effects of recombinant human IL-4 (rhuIL-4) on stem cell factor (SCF)-dependent fetal liver-derived human mast cells in liquid culture. In no case did rhuIL-4 augment proliferation of mast cells. rhuIL-4 selectively inhibited certain aspects of the development of mast cells in cultures of fetal liver cells with rhuSCF. These include lower numbers and percentages of cells expressing tryptase and surface Kit, smaller cells, and lower contents of cells for tryptase, histamine, and Kit. Development of metachromasia was not attenuated. The downregulation of Kit, the surface receptor for SCF, is probably a critical factor, because cells lacking this molecule would not be able to respond to SCF. In contrast to mast cell progenitors, mast cells already developed in vitro from fetal liver cells are relatively resistant to rhuIL-4, but are still dependent for survival on the presence of rhuSCF.

Abortion, Therapeutic↗
PubMed1994

Hyperbaric oxygen improves wound healing in normal and ischemic skin tissue.

The influence of hyperbaric oxygen on reepithelialization and on microvascular perfusion of wounds in normal and ischemic skin tissue was investigated by using a standardized model, in ears of hairless mice. Animals were treated within 2 hours of wound creation and then twice daily with 100% oxygen at 2 atmospheres of absolute pressure. Ischemia was induced by ligating two of the three major vessels of the ear 2.5 days before wound creation. Wound surface area was measured every third day after wound creation. In addition, microvascular blood flow before and during the wound healing process was measured by scanning the ear with a new laser Doppler perfusion imager. In normal tissue (n = 13), hyperbaric oxygen therapy significantly accelerated wound healing by 2 days (p < 0.01) as compared with controls (n = 16). In ischemic tissue (n = 16), treatment with hyperbaric oxygen reduced time for reepithelialization in control animals (n = 16) from 14.3 to 9.9 days (p < 0.001). Laser Doppler data showed no difference in tissue blood flow between treated and untreated animals. In comparison with normal tissue, wound healing in ischemic tissue was characterized by a reduced and less intense hyperemic response. These data suggest that hyperbaric oxygen therapy improves reepithelialization in normal and ischemic skin tissue. The beneficial effect is not associated with changes in microvascular perfusion and therefore is probably due to high arteriolar oxygen content and oxygen diffusion.

Animals↗
PubMed1994

Phenotypic characterization of the human mast-cell line HMC-1.

The cell line HMC-1, derived from a patient with mast cell leukaemia, is the only established cell line exhibiting a phenotype similar to that of human mast cells. This paper reports on a detailed characterization of the expression of a panel of markers for various types of immature and mature haematopoietic cells in the HMC-1. We also studied the potential of HMC-1 to differentiate upon treatment with conditioned media from the human T-cell line Mo, retinoic acid or DMSO. HMC-1 was found to express several mast cell-related markers. A high expression of Kit, the receptor for stem-cell factor, was detected. The majority of the cells were stained with a MoAb against the mast cell-specific serine protease tryptase. Of particular interest was the finding that beta-tryptase mRNA, but not alpha-tryptase mRNA, was expressed in HMC-1. Using enzyme-histochemistry we were able to show that the beta-tryptase was enzymatically active, indicating that tryptase can form active homotetramers. Both heparin and chondroitin sulfate were found to be present in approximately equal amounts. HMC-1 lacked surface expression of the high-affinity IgE receptor, which was confirmed by the absence of mRNA of the alpha- and beta-chains of the IgE-receptor complex. However, a strong expression of the gamma-chain of the IgE-receptor complex was detected. A positive staining of the monocyte/macrophage marker CD68 was obtained, as well as a strong hybridization signal for the eosinophilic/basophilic-related differentiation marker the Charcot-Leyden crystal. Treatment of HMC-1 with conditioned media from the human T-cell line Mo, retinoic acid or DMSO induced only moderate changes in the surface or intracellular expression of the studied markers. The agents tested neither induced any of the monocyte/granulocyte markers examined, nor expression of the Fc epsilon RI alpha-chain.

Amino Acid Sequence↗