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Biomedical subjects

P Behrens

Publications and source records attributed to P Behrens.

63 records · Page 4Linked to original sources
PubMed1984

[An improved connecting system for artificial hearts].

The certain connection of the artificial ventricles to the vascular system has a decisive importance in the implantation of an artificial heart. Demands concerning tightness, reliability, easy attendance, and anatomic fit are to be considered especially in the construction of a suitable connecting system. A modified bayonet system came in use. The connection between the artificial heart and the vascular system is placed here by distortions of a tightening ring.

Animals↗
PubMedDate not supplied

[Biomechanical properties of cartilage repair tissue after different cartilage repair procedures in sheep].

AIM: The purpose of this study was to evaluate the biomechanical quality of cartilage and repair tissue in a sheep's knee. 4 standardized 7 mm defects were created on the medial femoral condyle and on the patellar groove (n = 22). These were treated with 4 different cartilage repair procedures and examined 1 year later. MATERIAL AND METHODS: The different groups were: (1) a cell-seeded collagen type-I/III-membrane (Chondro Gide(R)) glued into the defect; (2) a collagen type-I/III-membrane, sutured and cells injected underneath; (3) an engineered, cell-seeded collagen type-II-membrane, glued; (4) periosteum sutured and cells injected underneath; (5) CONTROLS: healthy contra-lateral knees. Indentation tests were performed to reveal the biomechanical capacity. From creep indentation over 35 s a "25-s creep index" was calculated. A high creep index means that the cartilage can undergo greater and faster compression. RESULTS: The repair tissue was significantly thinner than the normal cartilage. The mean creep index of all repair tissues was measured at 111 and 125, respectively (p < 0.05). There were no significant differences among the treated groups. CONCLUSION: In this animal study, none of the induced repair tissues was biomechanically comparable to genuine articular cartilage.

Animals↗
PubMedDate not supplied

[Indications and implementation of recommendations of the working group "Tissue Regeneration and Tissue Substitutes" for autologous chondrocyte transplantation (ACT)].

For the treatment of full-thickness articular cartilage lesions of the knee joint, as a result of trauma or osteochondritis dissecans, a variety of biological reconstruction techniques have been developed. Different studies, some of which were performed as randomised, prospective clinical studies, showed that the autologous chondrocyte transplantation (ACT) provides the most satisfying and reliable method of cartilage reconstruction in the adult when applied to defects exceeding 4 cm (2). Based on these results, ACT seems to be of economic benefit, as the risk of developing osteoarthritis correlates significantly with the size of the cartilage defect, when not treated properly and in time. Surveying the studies on basic scientific aspects of ACT, cartilage defect animal models and clinical studies, it can be concluded that clinical results of ACT depend on a variety of factors. In this review, published by the joined advisory board of the German Societies of Traumatology (DGU) and Orthopaedic Surgery (DGOOC), we summarize the current knowledge available and the state of the art concerning ACT. Especially we discuss the advantages of different procedures, methods for treating knee cartilage defects and factors that influence the outcome of the different treatment regimens, with the aim to develop guidelines for the correct indication and application of the ACT.

Adult↗
PubMedDate not supplied

[The principle of autogeneic rib perichondrial transplantation in the treatment of deep articular cartilage defects].

The purpose of this study was to examine the fate of autologous perichondrial grafts after transplantation into cartilage lesions in weight-bearing joints. Results were evaluated depending on the age of the animals and on the weight-bearing conditions. Osteochondral lesions were drilled in the articular surface of knee joints in 36 adolescent sheep. The defects were filled with autologous rib perichondrial grafts which were secured by either collagen sponges (n = 12) or fibrin glue (n = 12). Twelve animals served as controls. Following one week of immobilisation the animals were allowed to move freely. Animals were sacrificed after 4, 8, 12, and 16 weeks. The same procedure was performed in three adult animals in order to achieve hints regarding the age-dependent ingrowth of the transplants. In two of them the transplantation was done using fibrin glue for fixation; one animal served as control. Grafts were removed corresponding to the time intervals and investigated histologically. In adolescent animals grafts from weight-bearing areas and control defects did not show a regular cartilagenous differentiation. In contrast to that, hyaline-like cartilage formation could be noted in non-weight-bearing areas even after 4 weeks. In principle, the same results were found in adult sheep but a delay of cartilagenous differentiation of four weeks was observed. Depending on these results we use the procedure of perichondrial transplantation clinically for treatment of circumscript deep lesions of articular cartilage provided no osteoarthritis or any other overlying general diseases are evident. By means of the Lysholm- and Ranawat-score all six patients demonstrated postoperative improvement. Furthermore, in two patients arthroscopic controls exhibited sufficient filling of the defects and ingrowth to the surrounding cartilage. Thus, autogeneic perichondrial transplantation can be recommended for treatment of circumscript deep cartilagenous lesions of articular cartilage.

Aging↗
PubMedDate not supplied

[Not Available].

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Germany↗
PubMedDate not supplied

Presence of genetic alterations in microdissected stroma of human colon and breast cancers.

BACKGROUND: Human carcinomas not only consist of neoplastic epithelial cells but also of tumor stroma, which may play an important role in tumor-progression. Whereas the tumor surrounding stroma is generally believed to represent a reactive component induced by tumor cell derived factors, a contribution of neoplastic cells to stroma formation via epithelium-mesenchyme transition during tumor invasion has become a novel concept in recent years. MATERIALS, METHODS AND RESULTS: We here show, by laser-assisted microdissection, that frequent genetic alterations in non-hereditary invasive human colon and breast cancers (loss of heterozygosity and TP53 mutations) occur not only in the neoplastic epithelial cells, but also in the adjacent fibroblastic stroma and that both components can share clonal features. CONCLUSION: Tumor cell-mesenchyme transitions are among the possible explanations for these findings and could actually occur during tumor invasion in vivo.

Breast Neoplasms↗
PubMedDate not supplied

Implication of the proliferation and apoptosis associated CSE1L/CAS gene for breast cancer development.

The CSEIL/CAS protein (CAS) is a Ran-binding protein with a function as a nuclear transport (export) factor. CSEIL/CAS, similar to Ran and other ran-binding proteins, plays at the same time an important role in the mitotic spindle checkpoint, which assures genomic stability during cell division. This checkpoint is frequently disturbed in neoplasms of various origin, including breast, hepatic and colonic tumors. CAS is located on chromosome 20ql3 and amplified in several cell lines, including breast, colon and bladder cancer. MEKl phosphorylation is known to be a reason for different CAS localization and activity. We evaluated the expression of CAS in 50 benign and malignant tumors of the breast by immunohistochemistry. Benign lesions of the breast (n=13) revealed a weak, predominantly cytoplasmatic CAS positivity. In ductal and lobular in situ carcinomas (n=17), 70-90% of the tumor cells were positive for anti-CAS staining which was predominantly cytoplasmatic. In invasive ductal and lobular carcinomas (n =20), 70-90% of the tumor cells stained positive with anti-CAS in a predominantly nuclear pattern. Different localization of CAS might affect its role not only for chromosome segregation, proliferation and apoptosis, but also its function in nuclear transport of proteins like retinoblastoma-gene-product, p53 and BRCAl. A different regulation in this checkpoint might contribute to the invasive potential in malignant carcinomas of the breast. Alteration of CAS-activity, possibly via MEKl-inhibition, might therefore be a possible option for breast cancer therapy.

Antibodies, Monoclonal↗