Biomedical subjects

K Sternberg

Publications and source records attributed to K Sternberg.

9 recordsLinked to original sources

PubMed2004

[Bioartificial materials in urology].

The scope of our research is the development of polymer-based bioabsorbable stents for urologic applications and in vitro testing of tissue reactions of cultured ureteral and urethral segments induced by implanted polymer stent prototypes. For these purposes a tissue cultivation model was developed using selected techniques of tissue engineering. Essential advantages of degradable over nondegradable urethral stents are elimination of the adverse extraction of epithelialized stents and the potential for recovery of organ-specific functionality. Moreover, the biocompatibility of a degradable urethral stent could potentially reduce the risk of restenosis due to hyperplasia and could be used, even repeatedly, for the treatment of a number of subvesical obstructions. For the treatment of tumor-induced strictures, application of degradable polymer stents coated with cytostatic drugs may be possible. The mechanical effect of the drug-loaded stent as a "place holder" could be complemented by adjuvant or palliative approaches such as local chemotherapy. We have developed and tested in vitro a degradable urethral stent incorporated with the model drug methotrexate for local drug delivery (LDD) by diffusion and during stent degradation.

Absorbable Implants↗

PubMed2000

Assessment of explanted PTCA balloons.

The data presented here are part of a on-going study to define the surface characteristics and properties of explanted PTCA catheters in a further effort to address some of the ramifications of the re-use issue. PTCA balloon catheter were examined after angioplasty in one hundred and sixty-eight patients (n = 168). This series included six balloon types from three manufacturers. The fresh fixed and dehydrated balloons were examined at first with light microscopy and then in a scanning electron microscope. X-ray semiquantitative microanalysis and FT-IR-ATR analysis were also performed on the balloons. Because most blood proteins are water soluble, we examined unfixed balloons with a protein silver staining kit for detection of adhered proteins described by Heukeshoven. A further method for protein detection is the Lowry-analysis. With this method water insoluble proteins can be observed. Our study has shown convincingly that all deployed angioplasty catheters were coated with adherent protein layers. Plaque particles were found embedded in the surfaces of most of the balloons examined. Fissuring and micro tearing of balloon surfaces was noted. FT-IR-ATR analyses of the blood contacted balloon surfaces did not show any peaks indicative of proteins on the balloon surface. The silver staining method also did not show any evidence of protein adsorption on the balloons. On the other hand, the Lowry-analysis yielded clear evidence that water insoluble proteins were adherent to the balloon surfaces. The average measured protein concentration was 17 microg/ml.

Angioplasty, Balloon, Coronary↗

PubMed1995

Alveolar macrophages from bronchoalveolar lavage of patients with pulmonary histiocytosis X: determination of phenotypic and functional changes.

In recent years the alveolar macrophage has been found to play a central role in interstitial lung disease. Pulmonary histiocytosis X is characterized by infiltrating fibroblasts, mononuclear cells, and CD-1-positive Langerhans cells. Bronchoalveolar lavage (BAL) fluid displays an increase of CD-1-positive cells and a remarkable exaggeration of the total cell count with only slight changes in the differential cell count. Changes of alveolar macrophage phenotype and functional activity occurring in pulmonary histiocytosis X have not yet been characterized. The BAL fluid of nine patients with histologically proven isolated pulmonary histiocytosis X was compared with that of 16 control patients. Immunophenotyping of alveolar macrophages by monoclonal maturation and differentiation markers of monocyte/macrophage lineage cells [Ki-M2, Ki-M6 (CD-68), Ki-M8, Ki-M1 (CD-11c)] revealed a significant increase of immature macrophages with a more monocyte-like phenotype. The proliferation marker Ki-67 revealed an increased proportion of proliferating macrophages. Functional analysis by measuring oxygen radical release revealed an increase both in baseline and stimulated luminol-enhanced chemiluminescence. Fibronectin production was elevated in alveolar macrophage supernatants from pulmonary histiocytosis X patients. These findings are consistent with phenotypic changes of alveolar macrophages in other interstitial lung diseases such as sarcoidosis and idiopathic pulmonary fibrosis. Local proliferation and the fresh influx of blood monocytes seem to be responsible for the increase in immature and functionally activated alveolar macrophages. The increase in oxygen radical release and fibronectin production suggests an augmented tissue injuring and fibrosing capacity of alveolar macrophages in pulmonary histiocytosis X.

Adult↗

PubMed1989