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Biomedical subjects

P Behrens

Publications and source records attributed to P Behrens.

At least 37 records · Page 2Linked to original sources
PubMed2001

Bartonella schoenbuchii sp. nov., isolated from the blood of wild roe deer.

The genus Bartonella comprises two human-specific pathogens and a growing number of zoonotic or animal-specific species. Domesticated as well as wild mammals can serve as reservoir hosts for the zoonotic agents and transmission to humans may occur by blood sucking arthropods or by direct blood to blood contact. Humans may come into intimate contact with free-ranging mammals during hunting, especially during evisceration with bare hands, when accidental blood to blood contact frequently occurs. The objective of this work was to determine the presence and the polymorphism of Bartonella strains in wild roe deer (Capreolus capreolus) as the most widely spread game in Western Europe. We report the isolation of four Bartonella strains from the blood of five roe deer. These strains carry polar flagella similar to Bartonella bacilliformis and Bartonella clarridgeiae. Based on their phenotypic and genotypic characteristics, three of the four roe deer isolates were different and they were all distinct from previously described Bartonella species. They can be distinguished from each other and from other Bartonella species by their protein profile, ERIC-PCR pattern, 16S rRNA and citrate synthase (gitA) gene sequences, as well as by whole DNA-DNA hybridization. In spite of their considerable heterogeneity, all four strains fulfil the criteria for belonging to a single new species. The name Bartonella schoenbuchii is proposed for this new species. The type strain R1T of Bartonella schoenbuchii has been deposited in the National Collection of Type Cultures as NCTC 13165T and the Deutsche Sammlung von Mikroorganismen und Zellkulturen as DSM 13525T.

Animals↗
PubMed2001

Downregulation of clusterin expression in testicular germ cell tumours.

OBJECTIVES: Clusterin is implicated in many biological processes including cell adhesion, apoptosis and transformation. Clusterin expression was demonstrated during sperm maturation and is overexpressed in different malignancies including breast and prostate carcinomas and anaplastic large-cell lymphomas. METHODS: The aim of this study was to determine the expression of clusterin in a series of different germ cell tumours by immunohistochemistry. Twenty-two seminomas, 27 embryonal carcinomas, 22 mature and immature teratomas, 8 yolk sac tumours and 1 chorion carcinoma as well as 30 normal testes were analysed using a monoclonal antibody. RESULTS: In normal testes strong signals were seen in the maturing germ cells and in Leydig cells. In most tumours examined no clusterin expression was detected (84%). Only a focal weak expression was seen in some teratomas (32%), embryonal carcinomas (15%) and yolk sac tumours (25%). CONCLUSIONS: Our results suggest that clusterin is associated with normal germ cell development and that the loss of clusterin expression might play a role in the malignant transformation of germ cells.

Biomarkers↗
PubMed2001

High expression of the proliferation and apoptosis associated CSE1L/CAS gene in hepatitis and liver neoplasms: correlation with tumor progression.

The CSE1L/CAS protein (CAS) is a Ran-binding protein with a function as nuclear transport (export) factor. Like recently observed for ran and other ran-binding proteins, CSE1L/CAS simultaneously plays a role in the mitotic spindle checkpoint, which assures genomic stability during cell division. This checkpoint is frequently disturbed in neoplasias of various origin, including hepatic tumors. We have evaluated by immunohistology the expression of CAS in adult and embryonic liver, hepatitis, and in liver hyperplasias. Normal hepatocytes revealed no CAS expression while embryonic liver showed strong expression in all parenchymal cells. Bile ducts stained positive with anti-CAS antibodies, and strong CAS expression was also detected at the interface between bile ducts and hepatocytes under conditions associated with regenerative proliferation. The localization of these CAS expressing cells correlated with the distribution of putative liver stem-cells. In active viral (but not in inactive) hepatitis, strong hepatocytal CAS expression correlates in site and intensity with degree of inflammation. Neoplastic liver demonstrated different degrees of CAS expression: no remarkable expression in adenomas, moderate expression in a narrow rim of hepatocytes and in periseptal cholangiolar proliferations in focal nodular hyperplasia, and strong CAS expression in hepatocellular carcinoma. Less differentiated tumors stain stronger than well differentiated. Cholangio-cellular carcinomas show even stronger CAS expression than hepatocellular carcinomas. Our observation of strong expression of CAS in liver cells that are committed for proliferation among them possibly liver stem cells, and in liver neoplasms, is consistant with the fact that CAS functions not solely as a nuclear transport factor but that it is also essential for cell proliferation, particularly for the mitotic spindle checkpoint. Interestingly, genomic instability is frequently observed in hepatic tumors which we have shown here to express large amounts of CAS. Since the degree of CAS-expression correlates with the grade of tumor dedifferentiation, we suggest that CAS should also be further investigated as prognostic marker for hepatic neoplasms.

Adult↗
PubMed2001

Invasive properties of serous human epithelial ovarian tumors are related to Ets-1, MMP-1 and MMP-9 expression.

The invasive potential of serous epithelial ovarian tumors is the main factor determining their biological behaviour. In contrast to invasive serous ovarian carcinomas serous borderline tumors generally present without stromal invasion and without or non-invading peritoneal implants. Little is known about the reasons underlying these differences. In the present study we found that two matrix-degrading metalloproteinases, collagenases 1 and 4 (MMPs 1 and 9), as well as the Ets-1 transcription factor are expressed at very low levels in serous benign cystadenomas, upregulated in the fibroblastic stroma, but not in the epithelium of borderline tumors and most strongly expressed in both stromal and epithelial tumor cells of serous invasive carcinomas. Since expression of Ets-1 and of MMPs 1 and 9 are topographically related, a transcriptional regulation of both proteases by Ets-1 is suggested. Upregulation of MMPs 1 and 9 within fibroblastic stromal cells of borderline tumors might be related to matrix remodelling and additional expression of both enzymes by the neoplastic cells of invasive carcinomas could then allow invasive propagation. The different expression patterns might supports the view, that no transition of serous borderline tumors into invasive carcinomas occurs.

3T3 Cells↗
PubMed2000

Lead hydro sodalite [Pb2(OH)(H2O)3]2[Al3Si3O12]2: synthesis and structure determination by combining X-ray rietveld refinement, 1H MAS NMR FTIR and XANES spectroscopy.

Ion exchange of the sodium hydro sodalites [Na3(H2O)4]2-[Al3Si3O12]2 [Na4(H3O2)]2[Al3Si3O12]2 and [Na4(OH)]2[Al3Si3O12]2 with aqueous Pb(NO3)2 solutions yielded, whichever reactant sodalite phase was used, the same lead hydro sodalite, [Pb2(OH)-(H2O)3]2[Al3Si3O12]2. Thus, in the case of the non-basic reactant [Na3(H2O)4]2-[Al3Si3O12]2 an overexchange occurs with respect to the number of nonframework cationic charges. Rietveld structure refinement of the lead hydro sodalite based on powder X-ray diffraction data (cubic, a = 9.070 A, room temperature, space group P43n) revealed that the two lead cations within each polyhedral sodalite cage form an orientationally disordered dinuclear [Pb2(micro-OH)(micro-H2O)(H2O)2]3+ complex. Due to additional lead framework oxygen bonds the coordination environment of each metal cation (CN 3+3) is approximately spherical, and clearly the lead 6s electron lone pair is stereochemically inactive. This is also suggested by the absence of a small peak at 13.025 keV, attributed in other Pb2+-O compounds to an electronic 2p-6s transition, in the PbL3 edge XANES spectrum. 1H MAS NMR and FTIR spectra show that the hydrogen atoms of the aqua hydroxo complex (which could not be determined in the Rietveld analysis) are involved in hydrogen bonds of various strengths.

Journal Article↗
PubMed2000

[In vitro culture of human autologous osteoblast cells on natural bone mineral].

Different methods are available for the treatment of osseous defects. In recent years the use of autologous bone was established as the golden standard. However, significant disadvantages are limited availability of the bone graft and its harvest implies additional morbidity for the patient. Alternatives to the use of autologous bone, as allogeneic bone from bone banks or biomaterials like hydroxyapatite are therefore of special interest. However, the currently available methods have severe disadvantages; allogenic bone carries a high risk of transmitting infectious diseases, most biomaterials show an unsatisfying osseous integration as well as prolonged healing with disability for the patient. Therefore, the aim has to be the development of a biomaterial that is as close as possible to human bone. In this in vitro study the natural bone mineral Bio-Oss/Orthos was used as a matrix for human osteoblast-like cells isolated from bone marrow of healthy patients. Even after three months the cell showed typical osteblast-like behaviour. Histologic evaluation demonstrated the ability of Bio-Oss/Orthos to guide cell growth within its matrix structure and therefore mimics in vivo situation of the healthy bone. The results show that culturing human osteoblast-like cells under standardised conditions is possible and that the combination of human osteoblast-like cell with an appropriate matrix may have the potential for a new treatment option of osseous defects.

Bone Density↗
PubMed2000

Characteristics of human chondrocytes, osteoblasts and fibroblasts seeded onto a type I/III collagen sponge under different culture conditions. A light, scanning and transmission electron microscopy study.

Hyaline cartilage has only a limited capacity of regeneration, thus, lesions of articular cartilage can lead to early osteoarthrosis. Current concepts in conservative orthopedic therapy do not always lead to satisfying results. As one new attempt to facilitate cartilage repair, autologous transplantation of articular chondrocytes is investigated in different assays. This study was designed to create a resistible and stable cell-matrix-biocomposite with viable and biosynthetically active human chondrocytes, osteoblasts or fibroblasts. This biocomposite might serve as an implant to treat deep osteochondral defects in the knee. We collected cartilage, spongiosa and skin probes from healthy patients undergoing hip-surgery and enzymatically liberated the chondrocytes, seeded them into culture flasks and cultured them until confluent. The spongiosa and the skin samples were also placed in culture flasks and cells cultured until confluent. After 4-6 weeks, cells were trypsinized and grown on a type I/III collagen matrix (Chondrogide, Geistlich Biomaterials, Wolhusen, Switzerland) for 7 days in standard Petri dishes and in a special perfusion chamber culture system. As controls, cells were seeded onto plastic surfaces. Then scaffolds were fixed and embedded for light microscopy and electron microscopy by routine methods. Light microscopically, chondrocytes grown on the surface of the scaffold form clusters or a dense layer of sometimes rather fibroblast-like and sometimes roundish, chondrocyte-like cells. Only a few cells grow deeper into the matrix. In transmission electron microscopy, the cells have a rather chondrocyte-like morphology which emphasizes the matrix-induced redifferentiation after dedifferentiation of chondrocytes in monolayer-culture in culture flasks. Chondrocytes on plastic surfaces have a spinocellular aspect with little signs of differentiation. Grown on Chondrogide, cells are more roundish and adhere firmly to the collagen fibrils of the scaffold. Osteoblasts grown on the collagen scaffold and examined by light microscopy form a thin cell-layer on the surface of the matrix with a reticular layer of dendritic cells underneath this sheet. Transmission electron micrographs show spinocellular and flat cells on the collagen fibrils. Scanning electron micrographs show large dendritic osteoblasts on plastic and a confluent layer of flattened, dendritic cells on the collagen scaffold. Fibroblasts form a thick multi-layer of typical spinocellular cells on the collagen matrix. Fibroblasts grown on plastic surfaces and examined by scanning electron microscopy also show a dense layer of fibroblast-like cells. For all three different types of cells no morphological differences could be seen when comparing cultivation in the perfusion culture system to cultivation in standard Petri dishes, although mechanical stress is believed to induce differentiation of chondrocytes. Especially the observed partially differentiated chondrocyte-matrix biocomposite might serve as an implant to treat deep cartilage defects, whereas osteoblasts and fibroblasts seem to be less suited.

Aged↗
PubMed2000

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

We 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 tumor stroma and that both components can share clonal features. Tumor cell-mesenchyme transitions are among the possible explanations for these findings.

Breast Neoplasms↗
PubMed1999

[New therapy procedure for localized cartilage defects. Encouraging results with autologous chondrocyte implantation].

Owing to the poor regenerative capacity of cartilage, cartilaginous defects are considered to represent pre-arthrotic factors. In addition to autologous and allogenic osteochondral fragments, proliferative tissue, such as periosteum and perichondrium are increasingly being used as graft material. The aim of treatment is to eliminate the defect and to restore the load-bearing capacity and function of the affected joint. A new, recently introduced, approach aims to stimulate the formation of new cartilage via autologous cultured chondrocyte implantation (ACI). The rationale for this treatment is the restoration of loadable hyaline or hyaline-like articular cartilage. Although long-term results are not yet available, clinical follow-up data obtained so far are encouraging. In addition to existing methods of treating cartilaginous defects, this article describes a modified method of transplantation of autologous chondrocytes. With this method the periosteal flap used to cover a defect is replaced by an absorbable collagenl/III membrane (Chondrogide, Geistlich Wolhusen, Switzerland) that is used as a carrier for the patient's own chondrocytes. After placement in the defect, the membrane is fixed in place with fibrin glue (MACI).

Arthroscopy↗
PubMed1999

[Ehlers-Danlos syndrome].

The Ehlers-Danlos syndrome (EDS) comprises a heterogenous group of nine hereditary connective tissue disorders, characterized by hyperelasticity of skin and hypermobility of joints to differing extents. The skin is easily injured and wound healing is delayed. The majority of EDS patients belong to EDS-types I-III. The pathogenesis in these cases is not known, although recent data suggest a role for collagen V. In contrast, the etiology of EDS-types IV, VI and VII has been found. While EDS IV is caused by a mutation in the collagen III gene, in EDS VI a mutation in the lysyl hydroxylase gene is present. In EDS VII, the underlying defect is a mutation in the collagen I gene. The EDS-types V, VII and X are very rare; their symptoms resemble those of EDS-type II.

Ehlers-Danlos Syndrome↗
PubMed1999

Development of a biocomposite to fill out articular cartilage lesions. Light, scanning and transmission electron microscopy of sheep chondrocytes cultured on a collagen I/III sponge.

The regenerative capacity of hyaline articular cartilage is limited. Thus, lesions of this tissue are a proarthrotic factor, and up to now the conservative treatment of cartilage lesions and arthrosis does not yield satisfying results. Therefore, autologous transplantation of articular chondrocytes is being investigated in a variety of different assays. The aim of our study was to create a mechanically stable cell-matrix implant with viable and active chondrocytes which could serve to fill out articular lesions created in the knees of sheep. For this purpose, articular cartilage was collected from knee lesions, chondrocytes were liberated enzymatically and seeded in culture flasks and cultured till confluency. Cells were then trypsinized and grown on a type I/III collagen matrix (Chondro-Gide, Geistlich Biomaterials, Wolhusen, Switzerland) for 3, 6 and 10 days before being fixed and embedded for electron microscopy by routine methods. Scanning electron microscopy was performed after dehydration in acetone, critical point drying and sputter-coating with gold-paladium. Light microscopically, clusters of chondrocytes can be seen on the surface of the matrix with a few cells growing into the matrix. Transmission electron microscopic photographs yield a rather differentiated chondrocyte-like appearance, which is evidence of a matrix-induced redifferentiation after dedifferentiation during the growth period in the culture flasks. Scanning electron microscopic results show large, flattened chondrocytes without signs of differentiation on plastic, whereas chondrocytes grown on the Chondro-Gide sponge show a more roundish aspect wrapping firmly around the collagen fibrils, exhibiting numerous contacts with the matrix. This cell-matrix biocomposite can now serve to fill out articular cartilage lesions created in the knees of sheep.

Animals↗
PubMed1998

Haematogenous tuberculous infection following revision of a loosened total hip replacement.

A case of tuberculous arthritis complicating revision of a total hip replacement (THR) is reported. Primary THR was performed for arthrosis of the hip and the patient underwent revision because of aseptic loosening. After this surgical procedure, secondary infection with Mycobacterium tuberculosis occurred. Bacterial contamination due to haematogenous spread probably from a reactivated old quiescent tuberculous pleural focus is proposed as the most likely source of infection in this patient. Tuberculous infections in THR are rare but prophylactic use of antituberculous drugs in patients with a history of tuberculosis may reduce the risk of reactivation of old foci and serve to eliminate contamination of prosthetic replacements.

Aged↗
PubMed1998

Cost analysis of three different surgical procedures for treatment of a pelvic tumour.

INTRODUCTION: Malignant pelvic tumours are rare, but adequate treatment is difficult because of anatomical and functional reasons. Different surgical procedures are recommended. Besides aspects influencing the quality of life due to the different surgical techniques, costs of these surgical procedures and the perioperative time interval, depending on the chosen surgical procedure, must also be considered. METHODS: Costs of three kinds of surgical treatment - internal hemipelvectomy vs external hemipelvectomy and application of an orthotic device vs ilio-femoral pseudoarthrosis - were compared, including costs of the immediate period of rehabilitation. Costs of the preoperative diagnostic procedure were excluded because they were assumed to be equal. For all calculations, treatment of a periacetabular pelvic tumour type II-b was assumed, according to the Enneking classification, with the need for a pelvic resection with wide margins including removal of the hipjoint. This analysis was performed based on the average costs per hour of physicians, nurses and physiotherapists, including a basic daily rate for additional costs, such as housekeeping and administrative costs of the hospital. In all cases, the costs of the operative procedure and the perioperative period up to 3 months were calculated, including the costs for the endoprosthetic device after internal hemipelvectomy and those for the orthotic devices after necessary external hemipelvectomy. RESULTS: For a postoperative period of 3 months, the cost for treatment with resection of the tumour and performing an ilio-femoral pseudoarthrosis is nearly DM 56,741.54; treatment with an internal hemipelvectomy including the endoprosthetic pelvic replacement costs DM 81,439.34; and treatment with external hemipelvectomy and application of an orthotic device with a pelvic cage costs DM 69,138.46. In this analysis, social costs due to the different rates of disability for years or costs of a new prosthetic device after years and aspects related to resulting quality of life were excluded. In contrast, costs of three different actual cases can differ significantly from the estimated costs. The most important influencing items are surgical implants, blood units and similar products, and surgical treatment of postoperative complications. CONCLUSIONS: Regarding all these aspects, limb salvage seems to be advantageous over amputation. Whether an ileo-femoral pseudoarthrosis or endoprosthetic pelvic replacement should be performed is a decision that should be made by the physicians. based on the underlying diagnosis and the correlated expected survival. Furthermore, additional factors probably reducing the rate of postoperative complications, such as infections or necrosis following radiotherapy and being summarised under the term "quality of life", should also be regarded.

Adult↗
PubMed1998

Autologous perichondral tissue for meniscal replacement.

Our aim was to examine the potential of autologous perichondral tissue to form a meniscal replacement. In 18 mature sheep we performed a complete medial meniscectomy. The animals were then divided into two groups: 12 had a meniscal replacement using strips of autologous perichondral tissue explanted from the lower rib (group G) and six (group C) served as a control group without a meniscal replacement. In all animals restriction from weight-bearing was achieved by means of transection and partial resection of tendo Achillis. Six animals (four from group G and two from group C) were each killed at 3, 6 and 12 months. The grafts and the underlying articular cartilage were removed and studied by gross macroscopic examination, light microscopy, SEM, polarised light examination, and by biomechanical tests. In all the transplanted animals a new perichondral meniscus developed. After three months the transplants resembled normal menisci in size and thickness, while in the control animals only small rims of spontaneously grown tissue were seen. Microscopically, the perichondral menisci showed a normal orientation of collagen fibres and normal cellular characteristics, but in the central region, areas of calcification disturbed the regular tissue differentiation. Healing tissue in control animals lacked the normal fibre orientation and cellularity. SEM of perichondral menisci showed surface characteristics similar to those of normal sheep menisci without fissures and lacerations; the control specimens had these defects. The femoral and tibial cartilage in contact with the new menisci had normal surface characteristics apart from one animal with slight surface irregularities. Control animals showed superficial lesions after three months which increased at six to 12 months postoperatively. Microangiography of the newly grown tissue demonstrated a less intense vascularisation after three months when compared with normal menisci. The failure stress and tensile modulus of perichondral menisci were significantly lower than those of normal contralateral menisci, and spontaneously regenerated tissue in meniscectomised animals had even lower values. There were no significant differences in values between newly grown perichondral menisci and spontaneously grown tissue.

Animals↗
PubMed1997

Semipreparative isolation of collagen types I, II, III and V by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electroelution.

A simple method for the isolation of alpha-chains of different collagen types was developed. The procedure involves sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by electroelution of separated and defixed collagen alpha-chains. Collagen types I, II, III and V from different porcine tissues were recovered in high quantity (> 95%) and purity (> 98%) as evidenced by amino acid analysis. The procedure can be used for sample quantities smaller than required for conventional methods e.g. chromatographic procedures.

Amino Acids↗
PubMed1997

Arthrolysis of the shoulder for ruptures of the rotator cuff.

Complete repair of tears of the rotator cuff may be difficult, but with superior arthrolysis by the Apoil-Dautry technique the lesion in the cuff is not treated. We report 17 patients who had this procedure for large cuff defects. The outcome is directly related to the duration of symptoms, and we only had good results in a few patients, although intensive physiotherapy improves function. A wide debridement is needed, followed by intensive physiotherapy for the deltoid and shoulder stabilising muscles. We recommended that this technique should be used in elderly patients who will put less demand on their shoulders.

Aged↗