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Biomedical subjects

R Kaufmann

Publications and source records attributed to R Kaufmann.

At least 199 records · Page 11Linked to original sources
PubMed1995

Influence of cytokine stimulation (granulocyte macrophage-colony stimulating factor, interleukin-3 and transforming growth factor-beta-1) on adhesion molecule expression in normal human bone marrow fibroblasts.

Interactions between stromal cells or extracellular matrix and hematopoietic cells are important factors for the very complex processes associated with differentiation and maturation in the bone marrow. To elucidate these multifold processes, the expression pattern of various adhesion molecules was studied on enriched fibroblastic populations derived from healthy volunteers. CD44 (homing cell adhesion molecule) and very late activation antigen beta 1 (VLA beta 1; CD29) could be demonstrated on almost all fibroblasts without an alteration following cytokine stimulation. On the other hand, VLA-2 (CDw49b), VLA-3 (CDw49c), VLA-4 (CDw49d), VLA-5 (CDw49e), intercellular adhesion molecule-1 (ICAM-1; CD54) and vascular cell adhesion molecule-1 (VCAM-1; CD106) were only represented by certain cell fractions. In our studies recombinant human granulocyte macrophage-colony stimulating factor failed to alter the expression pattern of these adhesion molecules, whereas recombinant human interleukin-3 (rhIL-3 showed a tendency for downregulation of the VLA antigens except for VLA beta 1. However, recombinant human transforming growth factor-beta 1 (rhTGF beta 1) exerted a reducing effect on the expression of VLA-3 and induced an increase in the VLA-5-positive fraction. In the immunoglobin class VCAM-1 revealed a decrease staining capacity after stimulation with rhTGF beta 1 and rhIL-3. Contrary to this finding, the presentation of ICAM-1 increased after administration of these mediators.

Bone Marrow↗
PubMed1995

Stable engraftment of human female genital mucous membrane xenografts on SCID mice.

We developed a model in which full-thickness human genital mucous membranes (fallopian tubes, endometrium) were heterotopically xenografted into the skin of severe combined immunodeficient (SCID) mice. The transplanted tissue retained its human phenotype for at least 4 weeks including the glandular epithelium, the lamina propria, and main parts of the grafted vessels. By using an occlusive chamber filled with covering phosphate-buffered saline we created a system that protected the moist human epithelial surface. This system will allow the study of the interaction of test substances, or of invasive, pathogenic microorganisms, with epithelial cells and other cellular components of the human genital mucosa under in vivo conditions.

Animals↗
PubMed1995

Influence of activation and differentiation of cells on the effectiveness of photodynamic therapy.

Photodynamic therapy combines photosensitizers absorbing light in the red spectral region and irradiation with light of the corresponding wavelength. To analyse the influence of cell differentiation on susceptibility to photodynamic therapy, we compared the proliferation inhibition induced by photodynamic therapy on normal human keratinocytes, spontaneously transformed human keratinocyte cell line HaCat and on squamous cell carcinoma lines. Cells were irradiated with polychromatic methylene blue as well as the precursor of protoporphyrin, 5-aminolevulinic acid. When incubated with Photosan-3, normal human keratinocytes exhibited and ED50 about 10-fold lower than the other cell lines studied. When methylene blue and 5-aminolevulinic acid were used, photodynamic therapy had comparable effects on all cell types. Stimulation of normal human keratinocytes with either EGF-alpha or IFN-gamma resulted in an increase susceptibility to photodynamic therapy when 5-aminolevulinic acid was used. This effect was more pronounced in the case of EGF-alpha. Our experiments suggest that activation and differentiation are two important parameters determining susceptibility to photodynamic therapy.

Aminolevulinic Acid↗
PubMed1995

[Intrathecal IgG synthesis: when is determination of oligoclonal bands necessary?].

Two quantitative methods of determining the intrathecal synthesis of IgG were tested for their usefulness in deciding about the necessity of further investigations of oligoclonal bands (OCB) in the CSF. For this purpose, in 2003 patients with various neurological diseases the intrathecal synthesis of IgG was determined by Reiber's formula and by the IgG index, as well as by the demonstration of OCB by isoelectric focusing (IEF). While OCB could be detected in no patient with an IgG index < 0.45, these bands were always demonstrated in patients with an index > 0.80. Even though arrange of 0.45-0.8 OCB was only detected in 268/1316 patients (20.4%), in 190/268 samples (70.8%) OCB were the only criterion for intrathecal synthesis of IgG. Calculation of intrathecal synthesis of IgG by Reiber's formula was less helpful in deciding about the necessity for IEF. Even though they had no intrathecal synthesis of IgG, as calculated by Reiber's formula, 189/1472 patients (12.8%) had OCB in the CSF. OCB were always detected if local production of IgG was > 12%. In patients with a severe damage of the blood-CSF barrier, calculation of the IgG index gave more false-positive results than calculations using Reiber's formula.

Adult↗
PubMed1994

Type B cholecystokinin receptors on rat glioma C6 cells. Binding studies and measurement of intracellular calcium mobilization.

To our knowledge, no brain derived cell line has been shown as yet to bear cholecystokinin(CCK)B receptors. In this paper, CCK binding sites were identified on rat C6 glioma cells. Pharmacological characterization demonstrated a single class of high affinity binding sites (Kd = 1.7 +/- 0.3 x 10(-10) M) and a binding capacity of 6.1 +/- 1.8 fmol/mg protein. These CCK binding sites displayed a typical CCKB pharmacological profile as shown in competition studies by using several CCK-related compounds and nonpeptide CCK antagonists discriminating between CCKA and CCKB sites. In order to demonstrate that CCK binding sites constitute a functional receptor CCK-8S induced mobilization of free intracellular calcium was investigated in single C6 cells by using a laser scanning confocal imaging system. Since rise in [Ca2+]i noted by stimulation of C6 cells with CCK-8S could be blocked by the CCKB receptor antagonist L-365,260 (100 nM) but not by the CCKA receptor antagonist L-364,718 (100 nM), CCK induced calcium signal is triggered by activation of CCKB receptors in C6 cells. The rat C6 glioma cell line may serve as a useful model for studying CCKB receptor in brain.

Animals↗
PubMed1994

In vivo targeting of integrin receptors in human skin xenografts by intravenously applied antibodies.

We examined whether systemically injected monoclonal antibodies (mAbs) directed to cell-surface glycoproteins of human keratinocytes reach their target antigens in xenograft transplants of normal human skin on SCID mice. The integrins alpha 6 beta 4, expressed in the basal cell layer of human epidermis, and glycoprotein T16 (gp 40/50), expressed in terminally differentiating keratinocytes of the stratum spinosum, were selected as targets. It was found that all injected mAbs selectively localized to their antigens and bound and saturated their targets even in the uppermost layers of the stratum malpighii. This could easily be monitored by direct immunofluorescence staining since SCID mice lack endogenous production of significant amounts of immunoglobulins. After a single injection, mAbs could still be detected at the target site after 14 days. Our results proved that heterologous immunoglobulins pass systemic capillary filters in this xenograft model and specifically bind to their target molecules. Thus, xenografted SCID mice provide a versatile model for studying cell-surface glycoprotein-mediated interactions by the use of functionally interfering antibodies under in vivo conditions in human skin.

Animals↗
PubMed1994

Photodynamic therapy in psoriasis: suppression of cytokine production in vitro and recording of fluorescence modification during treatment in vivo.

Photodynamic therapy (PDT) consists of the combination of photosensitizers absorbing light mainly in the red spectral region and irradiation with light of corresponding wavelengths. We analysed its effects on the cytokine secretion (IL-1 beta, TNF alpha, IL-6) of freshly isolated peripheral mononuclear cells from six patients with chronic plaque-stage psoriasis in comparison with PUVA. PUVA treatment resulted in a decreased production of all three cytokines, but most pronounced in the case of IL-6. PDT caused a similar change in the cytokine pattern, but its effectiveness was lower. In vivo fluorescence recordings were performed on psoriatic plaque lesions after topical application of the photosensitizer Photosan-3. Under irradiation, progressive photobleaching was noted with increasing radiation dosage. This is the first reported study of photochemical reactions using on-line fluorescence recordings during PDT of psoriatic lesions in vivo. Our results demonstrate the capacity of PDT to cause immunomodulatory effects similar to PUVA, thus indicating its potential application to the treatment of this common disease.

Cytokines↗
PubMed1994

Psoriasiform architecture of murine epidermis overlying human psoriatic dermis transplanted onto SCID mice.

Preliminary observations in a xenogeneic SCID mouse transplantation model indicated that murine epidermis overgrows human dermis from psoriatic skin but not that form normal skin. To investigate the effect of peripheral blood mononuclear cells on the differentiation of murine keratinocytes, we transplanted involved and uninvolved full-thickness skin from patients with psoriasis onto SCID mice and followed this with repeated subcutaneous injections of cells suspended in patient serum. After 6 weeks grafts were analysed morphologically and immunohistochemically. The epidermis in grafts from clinically uninvolved skin appeared normal. The persistence of a psoriasiform epidermis was noted in all grafts from affected sites despite a lack of lymphocytic infiltration. Staining for human and mouse MHC class I antigens revealed the murine origin of keratinocytes forming the psoriasiform epidermis, while the human dermis was retained. Our observations indicate that the defect underlying the pathogenesis of psoriasis is most likely located in the dermal rather than the epidermal compartment. This xenogeneic transplantation model may be useful for future studies of the pathogenesis and treatment of psoriasis.

Animals↗
PubMed1994

User trials on the colours and symbols for electronic charts.

The Electronic Chart Display and Information System (ECDIS) contributes to safe navigation by enabling the mariner to follow a planned route precisely, using positioning and radar information integrated on an electronic chart. The need to ensure that ECDIS is safe to use has prompted the development of performance standards for the presentation of information on electronic charts. As a step in working towards these presentation standards, user trials were conducted on shore and at sea using an ECDIS display to investigate presentation issues, which included colour combinations and symbols for ships and tracks, chart features, radar overlays, scale indicators and also display brightness for day and night viewing. Results of questionnaires indicated mariners' preferences and rated visibility of various colours and symbols. As a result of the shore trials, improvements were made to some of the symbols, which were then reevaluated during sea trials. Changes to the colours and symbols resulting from these trials will be included in the International Hydrographic Organization's Provisional Colour and Symbol Standards for ECDIS.

Journal Article↗
PubMed1994

CCKB receptor signaling in rat pituitary GH3 cells. CCK-8S-induced intracellular calcium mobilization by Ca2+ release and Ca2+ influx.

We describe the effect of sulphated cholecystokinin octapeptide (CCK-8S) on [Ca2+]i in rat pituitary GH3 cells. Investigations were performed on fluo-3 loaded cells by using a confocal imaging system MRC-600 (Bio-Rad). Because CCK-8S mobilized intracellular calcium in cells bathed in Ca(2+)-free buffer it must be able to release calcium from internal stores. Furthermore, influx of Ca2+ from outside the cells seems to contribute to CCK-8S induced increases in [Ca2+]i as demonstrated by calcium mobilization in GH3 cells preincubated with thapsigargin in Ca2+ containing buffer.

Animals↗
PubMed1994

Comparative 3H-CCK-8S binding studies on CCKB-type receptors in guinea-pig cortex and continuous cell lines.

The present study was undertaken to compare binding characteristics of CCKB-type receptors in guinea-pig cortex, Jurkat T-cells, GH3 cells and C6 cells. The rank order of potency of a variety of CCK agonists and antagonists in inhibiting specific [3H]CCK-8S binding was highly correlated for the 4 CCKB receptor models as demonstrated by a computer-assisted statistical analysis. Taking the ligand binding profiles as the criterion it is concluded that CCKB receptors in guinea-pig cortex, Jurkat T-cells, pituitary GH3 cells and rat glioma C6 cells share identical pharmacological properties.

Animals↗
PubMed1994

Cutting and skin-ablative properties of pulsed mid-infrared laser surgery.

BACKGROUND: Pulsed mid-infrared lasers allow a precise removal of soft tissues with only minimal thermal damage. OBJECTIVE: To study the potential dermatosurgical usefulness of currently available systems at different wavelengths (2010-nm Thulium:YAG laser, 2100-nm Holmium:YAG laser, 2790-nm Erbium:YSGG laser, and 2940-nm Erbium:YAG laser) in vivo on pig skin. METHODS: Immediate effects and wound healing of superficial laser-abrasions and incisions were compared with those of identical control lesions produced by dermabrasion, scalpel incisions, or laser surgery performed by a 1060-nm Nd:YAG and a 1060-nm CO2 laser (continuous and superpulsed mode). RESULTS: Best efficiency and least thermal injury was found for the pulsed Erbium:YAG laser, leading to ablative and incisional lesions comparable to those obtained by dermabrasion or superficial scalpel incisions, respectively. CONCLUSION: In contrast to other mid-infrared lasers tested, the 2940-nm Erbium:YAG laser thus provides a potential instrument for future applications in skin surgery, especially when aiming at a careful ablative removal of delicate superficial lesions with maximum sparing of adjacent tissue structures. However, in the purely incisional application mode pulsed mid-infrared lasers, though of potential usefulness in microsurgical indications (eg, surgery of the cornea), do not offer a suggestive alternative to simple scalpel surgery of the skin.

Aluminum Silicates↗
PubMed1994

Primary subcutaneous leiomyosarcoma exhibiting the characteristic immunophenotype positive for vimentin and desmin.

BACKGROUND: Primary subcutaneous leiomyosarcoma is a rare neoplasm composed of plump, elongated spindle cells arranged in interweaving fascicles. OBJECTIVE: Differential diagnosis might be facilitated by the use of immunohistochemistry. METHODS: A case of subcutaneous leiomyosarcoma was investigated histologically on paraffin-embedded tissue and immunohistochemistry was performed following standard procedures. RESULTS: The case reported exhibited light microscopic features and an immunophenotype characteristic of leiomyosarcoma. However, the intermediate filament desmin could only be found on a small number of tumor cells. CONCLUSION: Expression of these markers might vary considerably and immunoperoxidase stainings need to be carefully evaluated. Utilization of several antibodies directed against different desmin epitopes might be advantageous.

Aged↗
PubMed1994

The Helmholtz Total Artificial Heart Labtype.

To perform the first experimental tests for validation of a new gear unit concept, the pump chamber, diaphragm, and pusher plate design of an orthotopic electromechanical total artificial heart (TAH) (Helmholtz Labtype) was manufactured. In its early stage of development, it provides some of the most important features of the conceptual final artificial heart. The new gear unit transforms a uniform unidirectional rotational motor movement into translatory pusher plate movements, with resting phase in the end-diastolic position, and the angled pump chamber orientation determines the available space for the motor and gear unit. Furthermore, this labtype provides flexibility with regard to use of different types of structural parts for experimental investigations. The first in vitro test results, obtained with specially designed circulatory mockloops that simulate physiological preload and afterload conditions, are presented. They comprise pressure and flow generation, motor performance, efficiency, and energy consumption. The results prove the feasibility of the new gear unit concept for an electromechanical artificial heart and allow a reliable determination of the necessary performance of the future brushless DC motor for the first in vivo TAH model.

Blood Pressure↗
PubMed1994

Biopersistence of the mineral matter of coal mine dusts in silicotic human lungs: is there a preferential release of iron?

Toxic potency of quartz-containing dusts, including coal mine dusts, is usually inhibited by protective clay mineral layers on the surface of quartz particles. This investigation of 11 dusts recovered from lungs of coal miners with different silicosis grade shows that such layers persist during long-term contact with human lung tissues. On the other hand, the results suggest that an apparently preferential release of iron occurred in lungs with massive fibrosis. These preliminary results support the hypothesis of an iron-related harmfulness of coal mine dusts.

Coal Mining↗
PubMed1994

In vitro and in vivo effects of photodynamic therapy in cutaneous T cell lymphoma.

Photodynamic therapy consists of the combination of photosensitizers absorbing light in the visible spectral region and irradiation with light of corresponding wavelengths. We analysed its effects in comparison to PUVA treatment on cell lines MyLA and HuT78, established from patients with cutaneous T cell lymphomas. Proliferation was reduced to 50% by exposure to 7.5 J/cm2 UV-A (= ED50). This effect was increased more than 10-fold in the presence of 10 micrograms/ml 8-methoxypsoralen. The ED50 for photodynamic therapy using 630 nm light emitted by a dye laser and 10 micrograms/ml Photosan-3 was found to be about 1 J/cm2. In vivo fluorescence recordings during topical photodynamic therapy of mycosis fungoides lesions showed photo-bleaching and thus documented the triggering of photochemical reactions. Our observations document the capability of photodynamic therapy to inhibit proliferation of transformed T cells similar to PUVA, pointing out its potential in the treatment of cutaneous T cell lymphomas.

Cell Line↗