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Biomedical subjects

M Thurnher

Publications and source records attributed to M Thurnher.

At least 37 records · Page 2Linked to original sources
PubMed1998

Local and systemic reactions after lung contusion: an experimental study in the pig.

The present study was designed to investigate the consequences of isolated unilateral lung contusion on local alveolar and systemic inflammatory responses in an animal model in the pig. Isolated unilateral lung contusion was induced by bolt shot in eight mechanically ventilated animals under general anesthesia (sham: n=4). Plasma and bronchoalveolar lavage fluid were collected during a period of 8 h following lung contusion. Leukocytes, leukocyte neutral protease inhibitor (LNPI), terminal complement complex (TCC), thrombin-antithrombin-complex (TAT) as well as pulmonary microvascular permeability and surfactant function were determined. Within 30 min, lung contusion was found to cause a significant local and systemic increase in TCC and TAT concentrations and a systemic increase in LNPI concentrations. The latter was accompanied by a sequestration of leukocytes in the contused lung. Complement activation and leukocyte sequestration in the contused lung progressively increased during the investigation period. Although surfactant function decreased in the entire lung 30 min after contusion, TCC, TAT, and leukocyte sequestration was unchanged in the contralateral lung. The first indication of an involvement of the contralateral lung was obtained by an increase in leukocyte sequestration 8 h after lung contusion. Unilateral lung contusion initiates an early systemic activation of humoral and cellular defense systems. Involvement of the contralateral lung appears to be a secondary event caused by a systemic inflammatory reaction.

Animals↗
PubMed1998

Dendritic cell-based immunotherapy of renal cell carcinoma.

Dendritic cells potently stimulate antigen-specific immune responses and recent data indicate that they are also capable of eliciting antitumor immune responses. We are performing a pilot study which tests the safety and efficacy of antigen-loaded, cultured blood dendritic cells in patients with metastatic renal cell carcinoma. Dendritic cells are simultaneously pulsed with lysate from autologous tumor cells and with the immunogenic protein keyhole limpet hemocyanin. During the pulse, the cells are activated with a combination of tumor necrosis factor-alpha and prostaglandin E2. Patients receive 5-10 X 10(6) dendritic cells per intravenous infusion and up to six infusions at monthly intervals. The first results demonstrate that this treatment modality is very well tolerated and can be associated with strong immunological and clinical responses. The present article discusses the importance of dendritic cell maturation and the role of helper antigens in dendritic cell-based immunotherapy.

Animals↗
PubMed1998

Evaluation of needle size for breast biopsy: comparison of 14-, 16-, and 18-gauge biopsy needles.

OBJECTIVE: The purpose of our study was to compare the quantity and quality of tissue harvested from breast biopsy when using 14-, 16-, and 18-gauge "long-throw" needles. SUBJECTS AND METHODS: We performed a prospective randomized study in 64 patients with 66 breast lesions. Under stereotactic guidance, passes were made in random order with each of the three biopsy needles in each lesion. Samples were measured for tissue area and scored for their quality. All lesions, including benign and malignant lesions and lesions with and without microcalcifications, were analyzed. Findings of the biopsy samples were compared with the final diagnoses made at surgical excision. RESULTS: In all 66 lesions, 14-gauge biopsy needles obtained significantly larger specimens (14-gauge, 13.14 mm2; 16-gauge, 9.6 mm2; 18-gauge, 6.41 mm2; p < .05) and scored significantly better (14-gauge, 8.37; 16-gauge, 7.56; 18-gauge, 7.14; p < .016) than either of the smaller needles. The results for malignant and benign lesions and for lesions with and without microcalcifications were similar but not equal to the overall results. However, benign lesions and areas with microcalcifications seem to be more problematic for both smaller needles than for 14-gauge needles. CONCLUSION: Our results indicate that the quantity and quality of breast biopsy specimens depend on the needle size. Of the three needle sizes tested, only 14-gauge long-throw biopsy needles can be recommended for breast biopsy.

Biopsy, Needle↗
PubMed1997

Prostaglandin E2 and tumor necrosis factor alpha cooperate to activate human dendritic cells: synergistic activation of interleukin 12 production.

Interleukin (IL)-12 is a proinflammatory cytokine that contributes to innate resistance and to the development of antigen-specific T cell responses. Among other effects, prostaglandin E2 (PGE2) inhibits the production of IL-12 by macrophages activated with lipopolysaccharide (LPS). Here we investigated the effects of PGE2 on human dendritic cells (DCs) which develop in the presence of GM-CSF and IL-4. We demonstrate that in the absence of LPS, PGE2 dose dependently stimulated the production of IL-12 by DCs. Although PGE2 alone stimulated the production of low amounts of IL-12 only, it synergized with tumor necrosis factor (TNF)-alpha to induce high levels of IL-12 production by DCs. Addition of TNF-alpha in the absence of PGE2 had no effect on IL-12 production. Conversely, in the presence of LPS, PGE2 inhibited IL-12 production by DCs in a dose-dependent manner. The combination of PGE2 and TNF-alpha efficiently silenced mannose receptor-mediated endocytosis in DCs and readily induced neo-expression of the CD83 antigen. In addition, the expression of various surface antigens such as major histocompatibility complex class I and II, adhesion, as well as costimulatory molecules was upregulated by this treatment. The effects of PGE2 on IL-12 synthesis and CD83 expression could be mimicked by dibutyryl-cAMP and forskolin, indicating that they were due to the intracellular elevation of cAMP levels. DC treated with PGE2 and TNF-alpha were most potent in stimulating allogeneic T cell proliferation. Our data demonstrate that PGE2 contributes to the maturation of human DCs and that PGE2 can be a potent enhancer of IL-12 production by human DCs.

Antigen Presentation↗
PubMed1997

The phosphatidyl-myo-inositol anchor of the lipoarabinomannans from Mycobacterium bovis bacillus Calmette Guérin. Heterogeneity, structure, and role in the regulation of cytokine secretion.

Lipoarabinomannans are major mycobacterial antigens capable of modulating the host immune response; however, the molecular basis underlying the diversity of their immunological properties remain an open question. In this study a new extraction and purification approach was successfully applied to isolate ManLAMs (lipoarabinomannans with mannosyl extensions) from bacillus Calmette Guérin leading to the obtention of two types of ManLAMs namely parietal and cellular. Structurally, they were found to differ by the percentage of mannooligosaccharide caps, 76 and 48%, respectively, and also, thanks to a new analytical method, by the structure of the phosphatidyl-myo-inositol anchor lipid moiety. A novel fatty acid in the mycobacterium genus assigned to a 12-O-(methoxypropanoyl)-12-hydroxystearic acid was the only fatty acid esterifying C-1 of the glycerol residue of the parietal ManLAMs, while the phosphatidyl unit of the cellular ManLAMs showed a large heterogeneity due to a combination of palmitic and tuberculostearic acid. Finally, parietal and cellular ManLAMs were found to differentially affect interleukin-8 and tumor necrosis factor-alpha secretion from human dendritic cells. We show that parietal but not cellular ManLAMs were able to stimulate tumor necrosis factor-alpha secretion from dendritic cells. From these studies we propose that the 1-[12-O-(methoxypropanoyl)-12-hydroxystearoyl]-sn-glycerol part is the major cytokine-regulating component of the ManLAMs. It seems likely that modification of the ManLAM lipid part, which may occur in hostile environments, could regulate macrophagic mycobacterial survival by altering cytokine stimulation.

Antigens, Bacterial↗
PubMed1997

Basic fibroblast growth factor levels in cancer cells and in sera of patients suffering from proliferative disorders of the prostate.

BACKGROUND: Both benign and malignant growth of the prostate depend on the induction of a microvasculature. Basic fibroblast growth factor (bFGF), a potent angiogenic factor, is thought to play an important role in this process. METHODS: bFGF expression in prostatic carcinoma was assessed by ELISA, reverse transcription polymerase chain reaction, and immunohistochemistry. RESULTS: DU-145 and PC-3 tumor cells produced bFGF. Almost 80-90% of it was localized in the cytoplasm, and 10-20% was associated with extracellular matrix components. Immunohistochemical analysis of prostatic tissue sections showed that cancer cells stained more intensively as compared to putatively healthy epithelium. In prostate cancer patients, mean bFGF serum levels were significantly elevated when compared to a healthy control group (6.64 pg/ml vs. 1.28 pg/ml). Serum bFGF levels did not correlate with any other clinical marker such as PSA, tumor stage, or grade. Four out of five patients who progressed to a more advanced stage showed an increase in serum bFGF levels. CONCLUSIONS: These results suggest that increased bFGF release may be associated with a more aggressive tumor phenotype.

Adult↗
PubMed1997

Human prostatic smooth muscle cells in culture: estradiol enhances expression of smooth muscle cell-specific markers.

Smooth muscle cells (SMCs) constitute a major cellular component of prostatic stroma. SMC tension plays an important role in urethral obstruction secondary to benign prostatic hyperplasia (BPH). We have developed an in vitro procedure for the propagation of human prostatic SMCs. Tissue specimens from patients undergoing radical prostatectomy or cystectomy were enzymatically disaggregated and cultured in MCDB-131 medium supplemented with horse serum, insulin, conditioned medium from the tumor cell line CRL-5813, and steroid hormones. The medium was assembled on the basis of the effects these supplements have on the growth of SMC cultures and on the expression of the two markers desmin and smooth muscle myosin. Addition of 0.1 microM of estradiol to the growth medium dramatically increased expression of these SMC-specific markers. Dihydrotestosterone (DHT) and hydrocortisone had a similar, albeit less pronounced effect. At three to five passages, about two thirds of the cells were immunohistologically positive for smooth muscle myosin or desmin. Almost all cells were positive for the myofibroblast marker smooth muscle alpha-actin throughout 10 passages and more. In SMC cultures, cells staining for smooth muscle myosin and desmin were found to seek direct contact to myofibroblasts. They grew in aggregates on a layer of myofibroblasts which adhered to the surface of the culture vessel. As revealed by transmission electron microscopy the cultured cells exhibited morphological features of myofibroblasts. Characteristics of smooth muscle cells, such as prominent bundles of microfilaments associated with dense bodies, basal laminae investing the cells, and numerous caveolae at the cell surfaces were regularly observed in cultures of low passages. After several passages, these features were markedly decreased and organelles of the biosynthetic system became more prominent. In summary, we present an in vitro model of prostatic SMCs and demonstrate that steroid hormones have characteristic effects on these cells. SMC cultures are expected to facilitate investigation of the functions and properties of human prostatic SMCs.

Actins↗
PubMed1997

Bacillus Calmette-Guérin mycobacteria stimulate human blood dendritic cells.

Bacillus Calmette-Guérin (BCG) mycobacteria have been used as adjuvant in the active immunotherapy of various human cancers. In addition, dendritic cells, which are the most potent antigen-presenting cells, have been shown to be capable of initiating anti-tumor immune responses. Here we investigated the effects of BCG on dendritic cells cultured from human blood. Addition of BCG resulted in rapid homotypic adhesion of dendritic cells. Moreover, BCG concentrations ranging from 10(4) to 10(6) bacteria/ml enhanced expression of the dendritic-cell-maturation antigen CD83 and of the T-cell co-stimulator CD86 (B7-2) in a dose-dependent manner. Concomitant with the increase of CD83 and CD86 expression, the cells lost the ability to capture soluble antigens, as determined by the exclusion of fluoresceinated Dextran molecules. Strikingly, the same dosages of BCG-bacteria stimulated TNF-alpha-gene transcription and TNF-alpha-protein release from dendritic cells in a dose-dependent fashion. BCG infection of dendritic cells in the presence of a neutralizing antibody directed against TNF-alpha inhibited CD83 expression by more than 50% indicating that the BCG-induced maturation of dendritic cells was at least partially mediated by dendritic-cell-derived TNF-alpha. The finding that BCG activates the most potent antigen-presenting cells reveals a plausible immunological mechanism of the occasionally observed anti-tumor activity of BCG.

Antibodies, Monoclonal↗
PubMed1997

Coaxial technique: approach to breast core biopsies.

PURPOSE: To assess the feasibility of the coaxial core breast biopsy technique performed under stereotactic and ultrasound (US) guidance in vitro and in vivo. MATERIALS AND METHODS: Biopsies were performed in vitro and in vivo with a coaxial technique. In vitro, the true needle-tip deviation was measured with a breast phantom on a stereotactic device with alteration of x and y axes. In vitro US studies were performed to evaluate the optimal technique for harvesting sufficient material for histologic work-up. In 205 patients, coaxial biopsy was performed in 210 suspicious lesions under US (61 lesions) or stereotactic (patient in the sitting position, n = 67; patient in the prone position, n = 82) guidance. In addition, the coaxial system was used for preoperative localization. Surgery and histologic work-up were performed in all cases. RESULTS: In vitro, the true needle-tip deviation was found to be less than indicated on the stereotactic device. A factor was introduced to correct this error. For US guidance, angulation or rotation of the coaxial needle within the lesion proved to be the best technique to increase the size of histologic specimen. Of the 210 lesions, 112 were benign and 98 were malignant. Agreement between biopsy results and final postsurgical histologic analysis was found in 205 cases (98%). CONCLUSION: The coaxial breast biopsy technique is an accurate, simple, and time-saving method performed under stereotactic or US guidance.

Adult↗
PubMed1997

In vitro generation of CD83+ human blood dendritic cells for active tumor immunotherapy.

There is increasing clinical interest in dendritic cells that are capable of initiating antitumor immune responses. Dendritic cells cultured from human blood mononuclear cells using granulocyte/macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4) are competent for antigen uptake but express relatively low levels of costimulatory molecules and thus correspond to immature resident tissue dendritic cells. In this study we took advantage of the new dendritic cell-specific marker CD83, which is expressed by mature dendritic cells, to delineate the maturation of cultured human blood dendritic cells. Although dendritic cells cultured with GM-CSF and IL-4 contained transcripts for CD83 as determined by reverse transcription PCR, CD83 protein was barely detectable by flow cytometry, confirming that dendritic cells obtained with this system are immature. However, treatment of dendritic cells with tumor necrosis factor-alpha (TNF-alpha) significantly increased the levels of CD83 transcripts and induced CD83 protein expression in dendritic cells. In contrast to the initiation of dendritic cell culture, which was facilitated by high cell density (5 x 10(6) cells/mL), differentiation into CD83+ dendritic cells required a low cell concentration (0.5 x 10(6) cells/mL). At higher cell density (1 x 10(6) cells/mL), CD83 expression was suppressed and was almost completely prevented at 2 x 10(6) cells/mL. Induction of CD83 expression was accompanied by a strong upregulation of the costimulator B7-2 (CD86) on dendritic cells. While untreated CD83(-) dendritic cells efficiently internalized fluoresceinated Dextran, TNF-alpha treated CD83+ dendritic cells excluded these molecules, confirming that maturation of dendritic cells was associated with the silencing of the antigen-capturing machinery. Morphologically, CD83+ dendritic cells presented with pronounced cytoplasmic projections (veils) characteristic of mature dendritic cells. In summary, we show that cell density critically regulates dendritic cell development. Knowledge of the appropriate conditions for dendritic cell generation and maturation will be important in clinical immunotherapy settings.

Antigens, CD↗
PubMed1996

Human renal-cell carcinoma tissue contains dendritic cells.

Immune surveillance of cancer requires antigen-presenting cells which activate T cells specific for tumor-associated antigens. We show here that substantial numbers of dendritic cells, which are the most potent antigen-presenting cells, emigrate from renal-tumor explants in organ culture. Tumor-derived dendritic cells presented with all characteristics of mature dendritic cells. Dendritic cells could be identified by typical cytoplasmic projections (=veils). They expressed high levels of MHC products and of the co-stimulator CD86 (B7-2). Dendritic cells expressed the CD45RO isoform but not CD45RA. The most important point was that up to 9% of the emigrating leukocytes expressed the CD83 antigen, a specific marker for mature dendritic cells. CD83+ cells were approximately 40-fold enriched in the tumor tissue as compared to the peripheral blood. In contrast to cultured blood dendritic cells, tumor-emigrant dendritic cells had a reduced potential to capture soluble antigen, as shown by the exclusion of fluoresceinated Dextran molecules. Finally, in mixed leukocyte reactions, tumor-derived dendritic cells were able to stimulate naive T cells from cord blood, which is a unique feature of dendritic cells. This study demonstrates that genuine dendritic cells reside in or infiltrate renal-cell carcinoma tissue. The failure of patients with renal-cell carcinoma to mount an anti-tumor immune response despite the presence of professional antigen-presenting cells in the tumor tissue suggests that tumor-associated dendritic cells are suppressed in situ, in a similar way to that described for tumor-infiltrating lymphocytes.

Antigens, CD↗
PubMed1996

Regulation of prostatic growth and function by peptide growth factors.

Polypeptide growth factors are positive and negative regulators of prostatic growth and function. Expression and biological effects of epidermal growth factor (EGF), transforming growth factors (TGFs) alpha and beta, fibroblast growth factors (FGFs), and insulin-like growth factors (IGFs) in the prostate have been extensively studied. EGF and TGF alpha, which share the same receptor, are strong mitogens for prostatic epithelial and stromal cells. Their paracrine mode of action in normal tissue and early-stage tumors is apparently altered towards an autocrine stimulation in hormone-independent tumors, which gain the ability to produce TGF alpha by themselves. TGF beta has a dual role in the regulation of prostatic growth. It inhibits growth of prostatic epithelial cells in culture and mediates programmed cell death after androgen withdrawal. However, advanced prostatic carcinomas become insensitive to the inhibitory effect of TGF beta. Several members of the FGF family have been identified in the prostate. They are mainly or exclusively expressed in the stromal cells, and stimulate the epithelial cells. In the rat Dunning tumor model, progression is accompanied by distinct changes in the expression of FGFs and their receptors. In the hyperplastic tissue, basic FGF (bFGF) is accumulated. This growth factor is also a potent angiogenic inducer, expression of which may determine the metastatic capability of a tumor. IGFs are paracrine growth stimulators in the normal and hyperplastic prostate. It is still under consideration whether prostatic cancer cells gain the ability to produce IGF-I by themselves and thus shift to an autocrine mode of IGF-I stimulation. Growth factors also interact with the androgen-signaling pathway. IGF-I in particular, other growth factors as well, can activate the androgen receptor.

Animals↗
PubMed1996

Nailing versus plating in thoracic trauma: an experimental study in sheep.

In this study, femoral intramedullary pressure, fat embolization, and pulmonary response were measured during reamed and unreamed nailing and plating of femoral fractures after blunt thoracic trauma. Intramedullary peak pressures of 425 mm Hg (mean 205 mm Hg) occurred in the reamed nail group (group I) during reaming with the 9-mm reamer, while in the unreamed nail group (group II) peak values were seen during nail insertion (330 mm Hg) with a mean of 203 mm Hg. Plating never led to a pressure rise over 67 mm Hg (mean 37 mm Hg). In reamed nailing, the most intense embolism was identified under ultrasound imaging with the large awl and with the 9.0-mm reamer (mean 2.2) and in the unreamed nail group during nail insertion (mean 2.8). Minimal echoes appeared during plating. The pulmonary arterial pressure did not vary significantly postoperatively between the three groups (p < 0.08). Our findings indicate that intramedullary fracture fixation causes a higher increase of intramedullary pressure and more fat and bone marrow embolization than extramedullary ones. Nevertheless, only minimal differences in the pulmonary hemodynamic response (pulmonary arterial pressure) were noted even in the presence of thoracic trauma.

Animals↗
PubMed1995

Dendritic antigen-presenting cells from the peripheral blood of renal-cell-carcinoma patients.

Dendritic cells are considered to be the initiators of immune responses, including those directed against tumors. Clinical research on dendritic cells was long hampered by the limited availability of these cells. The recent identification of cytokine combinations that mobilize dendritic cells with potent antigen-presenting cell function from peripheral blood represented a major progress. We show in this study that substantial numbers of dendritic cells can be obtained from the peripheral blood of patients with renal-cell carcinoma. The procedure requires a relatively small blood sample (40 ml) and avoids both priming of the patient with granulocyte-colony stimulating factor and leukapheresis. Approximately 2 to 8 million cells with the characteristics of dendritic cells could be obtained: phase-contrast microscopy revealed the typical cytoplasmic processes or veils; phenotypic analysis confirmed expression of dendritic-cell-associated molecules, including MHC class II, CD1a, CD4, ICAM-1 (CD54), LFA-3 (CD58), B7-1 (CD80) and B7-2 (CD86), and absence of T-cell, B-cell and monocyte markers; in addition, these cells rapidly attached to and migrated on collagen-type-1-coated surfaces. Interestingly, attachment was accompanied by acquisition of the CD14 antigen; functionally, cultured dendritic cells proved to be very potent co-stimulators of the phytohemagglutinin-induced proliferation of autologous tumor-infiltrating lymphocytes. The reproducible growth of functional dendritic cells from cancer patients is encouraging for the design of immunotherapy protocols.

Adult↗
PubMed1995

Tumor-infiltrating T lymphocytes from renal-cell carcinoma express B7-1 (CD80): T-cell expansion by T-T cell co-stimulation.

B7-1 (CD80) provides co-stimulation for T-cell activation by interacting with CD28 or CTLA4. Here we demonstrate the expression of B7-1 in freshly isolated and cultured lymphocytes from renal-cell carcinoma. In fresh preparations of lymphocytes infiltrating renal-cell-carcinoma tissue, B7-1 mRNA could readily be detected by reverse transcription PCR, and 2-color flow-cytometry analysis revealed substantial B7-1 expression on T cells from these isolates. As expected, tumor-derived T cells also expressed CD28, the B7 receptor. While B7-1 expression of tumor-derived T cells was maintained during culture in interleukin-2-supplemented medium, CD28 expression was further enhanced. We also show that B7-1 is functionally involved in T-cell expansion: anti-B7-1 MAb inhibited the PHA-induced proliferation of tumor-derived B7-1+ T cells (35%) in the absence of exogenous antigen-presenting cells, indicating that B7-1 mediates T-T cell co-stimulation (self-co-stimulation). Our data demonstrate that T cells infiltrating renal-cell carcinoma express B7-1, and that mutual co-stimulation via the B7-1/CD28 pathway contributes to the interleukin-2-driven expansion of tumor-derived T cells in vitro. The frequency of B7-1+ T cells in tumor lesions and the level of B7-1 on these cells may determine the time course of T-cell expansion in vivo. Self-co-stimulation, however, might also represent one mechanism leading to the state of suppression or anergy characteristic of tumor-infiltrating lymphocytes.

B7-1 Antigen↗