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Biomedical subjects

A Wilke

Publications and source records attributed to A Wilke.

At least 109 records · Page 6Linked to original sources
PubMed1975

[Integration of palmitat-1-14-C in lecithine and phospholipid content in normal and micro-embolized rabbit lungs (author's transl)].

Glass microspheres were used for a diffuse pulmonary microembolisation, as a modell for shock lung. Microembolisation is regarded as an important factor in pathogenesis of shock lung. The capacity of lung for lecithin synthesis was measured with palmitat-1-14-C incorporation. The phospholipid content and the composition of the fatty acids of lecithin were investigated. From the results it was possible, that the surfactant system may alterated by the vascular blocking. The dates supporting the importance of microembolisation in pathogenesis of shock lung.

Animals↗
PubMedDate not supplied

Comparison of German St. John's wort products according to hyperforin and total hypericin content.

OBJECTIVES: To compare the hyperforin and hypericin content of currently available St. John's wort products and to determine their batch-to-batch reproducibility. DESIGN: Representative products were obtained either directly from the manufacturer or purchased from pharmacies in and around Frankfurt, Germany. For five batches from each of the eight manufacturers, 10 individual dosage forms (tablets or capsules) were analyzed for both hyperforin and hypericin content. SETTING: Laboratories of the Institute of Pharmaceutical Chemistry at Johann Wolfgang Goethe University, Frankfurt, Germany. PRODUCTS: Eight German St. John's wort products containing from 250 mg to 612 mg dry extract were studied. Three of these products are capsules, four are film-coated tablets, and one is a sugar-coated tablet. Two of the products (Jarsin 300 and Neuroplant 300) are also available in the United States. METHODS: Hyperforin concentrations were analyzed by high-performance liquid chromatography. Total hypericin concentrations were determined by polarography, an electrochemical method. Concentrations were compared among different batches of the same product and among products from different manufacturers. RESULTS: The products contained widely differing amounts of hypericin and hyperforin, even after correcting for differences in the amount of extract per dose. Some products demonstrated consistent concentrations of hyperforin and hypericin from batch to batch, others exhibited pronounced interbatch variability. CONCLUSION: The St. John's wort preparations studied exhibited large differences in hypericin and hyperforin content and are not interchangeable for the treatment of mild-to-moderate depression. Pharmacists should take this variability into account when counseling patients on the use of St. John's wort products.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Psychogenic joint contractures exemplified by somatoform hysteria].

We would like to report about a 25-year-old female patient with a psychogenic knee contracture as part of a hysterical personality disorder. After having had multiple surgical procedures including 5 knee arthroscopies in 5 different orthopedic departments, we found a nearly full range of movement during an examination under general anaesthesia. Psychoanalytical investigations finally revealed a surprising, past history of the patient and her family. In addition we highlight the relevant literature.

Adult↗
PubMedDate not supplied

[Cytokine profile of a human bone marrow cell culture on exposure to titanium-aluminium-vanadium particles].

INTRODUCTION: The purpose of this study was to prove the effect of wear particles, especially Tivanium, in the mechanism of the aseptic loosening of total joint prostheses. MATERIALS AND METHODS: Therefore, human bone marrow cell cultures were incubated with titanium-aluminium-vanadium particles of different concentrations which were added after the seventh day of culture (10(9), 10(8), 10(7), 10(6) particles per ml medium). From this time starts the real culture period (2 weeks). During these two weeks the medium was changed and the supernatants were sampled. Using an ELISA the cytokine levels of interleukin-6, interleukin-1beta, TNF-alpha and LDH were measured approximately every second day (1, 3, 6, 8, 10, 14). As a marker for toxicity the activity of LDH was determined. RESULTS: Incubation of a human bone marrow cell culture with titanium-aluminium-vanadium particles led to a maximum release of interleukin-6, interleukin-1beta, and TNF-alpha at high particle concentration (10(9) particles per ml medium). An increase of interleukin-1beta was only detectable at particle concentrations of 10(9) per ml medium. Exposure of the human bone marrow cell culture to titanium-aluminium-vanadium particles was toxic for high particle concentrations (10(9) particles per ml medium), as reflected by release of the intracellular enzyme LDH. DISCUSSION: This study shows the ability of tivanium wear particles in a human bone marrow cell culture to induce a signfically higher release of proinflammatory and osteolytic mediators which are responsible for the aseptic loosening of prosthesis and the problem of revisions. In comparison to other cell studies, our results were explained by the human bone marrow cell culture. The human bone marrow is the real effector tissue source "in situ" because the prosthesis is localised intramedullarly.

Adult↗
PubMedDate not supplied

[Semiquantitative analysis of bone regeneration on porous metallic wire-mesh specimens with or without HA-coating in comparison to pure titanium in animal experiments].

INTRODUCTION: The aim of this study was to analyse the bone regeneration on porous metallic wire-mesh specimens of pure titanium, uncoated CoCrMb and HA-coated CoCrMb in a comparative animal experiment. MATERIAL AND METHODS: Uncoated and hydroxyapatite-coated CoCrMb (one-sided) specimens were tested in an animal experiment. The statistical interpretation was done macroscopically as well as microscopically. RESULTS: With regard to the histological and quantitative evaluation, it has been shown that the proximal coated CrCoMb implants were superior to the other specimen. The bone regeneration with the most distinctive extent of osseointegration has been seen by the HA-coated CrCoMb specimen. The uncoated distal CoCrMb specimen demonstrated the worst results. DISCUSSION: This study shows that specimens of titanium and uncoated CrCoMb implanted at the proximal metaphysis deliver comparable effects on the bone regeneration and osseointegration. The best results with regard to the bone regeneration and osseointegration were seen with the implanted hydroxyadaptite-coated CrCoMb specimen. In addition, it has been observed that the bone regeneration and osseointegration of the specimen depends on the place of implantation.

Animals↗
PubMedDate not supplied

[Total hip replacement in childhood, adolescence and young patients: a review of the literature].

AIM: Which implants and fixation techniques should be recommended in total hip replacements in children, adolescents and young adults? METHODS: A literature survey served to elucidate the results of recent papers in total hip arthroplasty (THA) over the last three decades. For this literature review the following items were used for a MedLine inquiry: "young patient", "children", "adolescents", "hip arthroplasty", "total hip replacement" and "hip endoprosthesis". Different disorders, implant types and surgical techniques were compared and discussed. RESULTS: Although some authors still favor a cementing fixation technique forA'acetabular shell and stem components in total hip replacements for young patients, most results of the present studies show the effectiveness of cementless fixation techniques. The indication for or against an implant should be include the preexisting diseases, daily activity, abnormal anatomic findings and consider the patient's expectations. Most studies investigated inhomogeneous probands treated with different implant types and are therefore of only limited appropriateness for reliable conclusions. CONCLUSIONS: Cementless fixation in THA is a sufficient technique in total hip replacement in young patients. There are only few data available in the literature dealing with the outcome of one implant type within a defined clinical picture.

Adolescent↗
PubMedDate not supplied

[Biocompatibility testing of various biomaterials as dependent on immune status].

INTRODUCTION: This study deals with the ingrowth behaviour of biomaterials (hydroxyapatite, cp-titanium, cobalt-chromium-molybdenum and PAEK) in relationship to the immunological competence in an animal model. Measured were the production of extracellular matrix (ECM) after implantation in non-immunocompetent naked mice and immunocompetent wild mice. Intention of the trial was to find out if either the immunological competence or the duration of implantation influences the quantity of produced ECM. In addition, the ingrowth behaviour was investigated under these conditions by using four different biomaterials. MATERIAL AND METHODS: Biomaterials (hydroxyapatite, cp-titanium, cobalt-chromium-molybdenum and PAEK) were implanted for 14 or 60 days, respectively. CLSM, SEM and SEM-EDX were used for analysis of the ECM and for measuring the distance between ECM and the biomaterials. CLSM was also used for the detection of collagen I and III as a parameter of the quality of osteointegration. RESULTS: In all cases a matrix grew on the surface of the biomaterials. The CLSM detected a co-localisation of collagen I and III. In the case of hydroxyapatite collagen I and III were found at a distance of 1 micro m over the surface. The largest space between the surface of the implant and the ECM was found in the case of PAEK. The smallest space was in the case of hydroxyapatite. In all investigated biomaterials the proportion of collagen I to collagen III varied through the duration of implantation. DISCUSSION: As is known from the literature we found different ingrowth behaviours on using different biomaterials. Furthermore, we found a statistically significant influence of the immunological competence of the host with regard to ECM production. We draw the conclusion that immunological competence improves the ingrowth behaviour of biomaterials.

Animals↗
PubMedDate not supplied

[Cell differentiation of a human bone marrow cell culture under the influence of UHMW-PE debris].

AIM: The purpose of the present study was to evaluate the influence of ultra-high-molecular-weight polyethylene (UHMW-PE), which is the major constituent of the material debris formed as a result of orthopaedic implant wear, on the cellular differentiation in a modified in vitro model. METHODS: UHMW-PE particles (Ø < or = 7.5 microm) were suspended in soluble collagen type I and subsequently solidified in different concentrations (10(5), 10(6) and 10(7) particles per well) on the bottom of the wells. Human bone marrow cells in a concentration of 3 x 10(6) cells per well were seeded on the collagen-particle substrate and maintained for up to 72 h. The response of the cells to the particles was examined by light microscopy, scanning electron microscopy and FACS analysis compared to cells on control collagen surfaces without any particles. RESULTS: Light and scanning microscopic evaluation revealed that the UHMW-PE particles, which had built large conglomerates (Ø 7.5 microm), were mainly surrounded by the cells and less phagocytosed. The results of the FACS analysis revealed significant differences in CD3/CD4 positive, CD14 positive and CD19 positive cells (p < 0.05). A significant elevation of CD3/CD4 positive and CD14 positive cells (p < 0.05) was observed after the period of culture (72 h) whereas a significant decrease could be detected in the case of CD19 positive cells. CONCLUSION: The results demonstrate that the particle-induced response by UHMW-PE limits itself not only to the particle macrophage contact but influences also the differentiation of the bone marrow. Moreover, the results confirm that the present method is useful to evaluate the in vitro effects of UHMW-PE wear particles with direct particle cell contact. Although the particles built large conglomerates, it could be shown that a change of the immune-competent cells also occurred.

Bone Marrow Cells↗
PubMedDate not supplied

[Minimally Invasive Stryker-Osteonics unicondylar knee prosthesis with metal-backed tibia component: a 5-year follow-up].

INTRODUCTION: The aim of this study was to evaluate the medium-term results of minimally invasive unicompartmental knee joint arthroplasty with a metal-backed tibia component. MATERIAL AND METHODS: Ninety-one unicompartmental knee replacements with a metal-backed tibia component, type SCR-Stryker Osteonics, were implanted in a minimally invasive technique in 91 patients between 1997 and 1999. The evaluation of medium-term results was based on The Knee Society Clinical Rating System by Insall and Scott and was done at 6 weeks, 1, 3 and 5 years after surgery. This rating system is based on the clinical and symptoms of the patient (maximum score 100). RESULTS: Preoperatively, the average knee score was 57.6 (44-66), the function score 63.3 (48-71). Throughout the period of investigation all patients had an increased knee and function score. One year after surgery the knee and function scores increased to 94.8 (39-100) and 93.6 (75-100). Five years post-implantation only 64 patients could be re-evaluated but they also had a knee and function score corresponding to the 3-year results [knee score: 98.2 (94-100); function score: 98.9 (85-100)]. Revision surgery using a total knee prosthesis was performed in 3 cases. DISCUSSION: The unicompartmental knee arthroplasty was a good surgical method for managing medial, unicompartmental arthritis of the knee joint. The results presented by the authors and corroborated by many literature data provide evidence that unicompartmental arthroplasty is of great importance in the treatment of unicompartmental knee arthritis. The results achieved by the minimally invasive technique of a unicompartmental knee arthroplasty with a metal-backed tibia component of the type Stryker-Osteonics were equal to the conventional surgical technique in literature. Good indications were patients older than 60 years with normal weight and normal sports activity. Well-functioning collateral and cruciate ligaments were mandatory. Moreover, the minimally invasive technique may lead to a shorter time of rehabilitation because of the reduced soft tissue damage.

Adult↗
PubMedDate not supplied

[Biocompatibility testing of different sterilised or disinfected allogenous bone grafts in comparison to the gold standard of autologous bone grafts--an "in vitro" analysis of immunomodulation].

INTRODUCTION: Repair of large skeletal defects using bone allografts has become a routine procedure in orthopaedic and trauma surgery. Different procedures of sterilisation (82.5 degrees C disinfection; 121 degrees C autoclaving; PES; Tutoplast; 25 kGy gamma irradiation) are available to inactivate bacteria and fungi, including their spores, as well as viruses in human bone allografts. The efficiency of these procedures has been proven. However, the effects on the cellular response are rarely investigated. This present in vitro study investigates the immunological answer of human bone marrow cells to human allogenous and autologous bone platelets which were sterilised by different methods. MATERIALS AND METHODS: Human bone marrow cells and the bone platelets were harvested from patients undergoing a total hip replacement. All patients provided informed consent. Human bone platelets, 10 mm in diameter, 3 mm in height, were produced from femoral heads which were removed within the scope of total hip replacements. They were sterilised by different procedures or were disinfected (gamma radiotherapy, PES/ethanol treatment, Tutoplast procedure, 121 degrees C autoclaving, > 82.5 degrees C thermodisinfection). In addition, an autologous in vitro bone donation was simulated and compared with the allogenous bone grafts. Endobon was evaluated as a bovine hydroxyapatite ceramic. As control a human bone marrow cell culture without bone platelets was used. Over a period of four weeks the changes of the immunogenic cell populations were analysed in vitro (FACS analysis). Light and scanning microscopy were done to reveal morphological differences. As a vitality test the trypan-blue staining was performed. RESULTS: Light and scanning microscopy demonstrated large differences between the various sterilisation and disinfection methods. After 4 weeks the autologous bone platelets were completely covered with homogenously distributed human osteoblast like cells. The heat-sterilised/disinfected transplants demonstrated similar effects compared to the autologous bone grafts while the irradiated bone platelets demonstrated less cell coverage. 2/3 of the cells were vital on average after four weeks, with the exception of the irradiated bone platelets. The FACS analysis revealed in comparison to the control group provable differences in the immunological answer for the autologous bone donation as well as for the differently sterilised or disinfected allogenous bone grafts. The heat sterilisation or, respectively, disinfection methods compared to the autologous bone donation demonstrated almost similar in vitro effects. By far the worst results, characterised by an excessively increased portion of cytotoxic T-cells and a decreased amount of viable cells, were seen in the 25 kGy gamma irradiation samples. CONCLUSIONS: The results demonstrate the influence of the different sterilisation and disinfection procedures on the differentiation of human marrow cells (host). Similar in vitro effects were seen for the autologous and heat-treated bone platelets. The treatment of allogenous bone grafts with PES/ethanol and the Tutoplast procedures showed, just as Endobon, only low differences in comparison with the control cultures. The worse results in the case of the irradiated bone platelets may be explained by the production of free radicals which led to an excessive cell death.

Blood Platelets↗
PubMedDate not supplied

[Comparative in vitro analysis of vacuum plasma-sprayed titanium implants--evaluation of OPG, Osteokalzin and AP expression].

INTRODUCTION: The purpose of this study was to evaluate the influence of different surface topographies on the expression of bone cell-associated proteins, such as osteoprotegerin (OPG), osteocalcin and alkaline phosphatase (AP), and the production of the extracellular matrix (ECM) in vitro. Another aspect was the question as to whether a hydroxyapatite (HA) coating offers additional advantages. Vacuum plasma-sprayed (VPS) pure titanium was used to generate different surface topographies. MATERIALS AND METHODS: The in vitro response of human bone marrow cells to VPS implants (porosity ranging from 25 to 50%, pore size ranging from 50 to 200 microm and roughness ranging from 0.191 to 0.547 mm) and cancellous structured titanium (cs-Ti) as a reference material (55% porosity, pore size of 500 microm, roughness 0.836 mm) were compared. The expression of bone cell-associated proteins, such as OPG, osteocalcin and alkaline phosphatase (AP), was evaluated. Scanning electron microscopy (SEM) was used to judge the production of ECM. RESULTS: All implant materials induced the release of OPG, osteocalcin and AP. Significant differences were evident between the cs-Ti and the different VPS-Ti surface structures. There was no difference in the response between the VPS-Ti surfaces. SEM showed a dense and increased production of ECM on the VPS-Ti surfaces. An additional HA coating caused a faster production of ECM and higher levels of OPG. CONCLUSIONS: The in vitro data presented here demonstrate the superiority of VPS-Ti surfaces over cs-Ti, which is already in clinical use. Differences between the VPS-Ti surfaces were not evident. Presumably, VPS-Ti surfaces offer good prerequisites for a successful integration of the implant in the surrounding tissue. An additional HA coating could influence these events positively.

Alkaline Phosphatase↗
PubMedDate not supplied

[Human bone marrow cell culture--a sensitive method for the evaluation of the biocompatibility of materials used in orthopedics].

The objective of the study was to develop a test system to determine the cytotoxicity and biocompatibility of different biomaterials used in orthopedic surgery. This system was based on the use of a human bone marrow cell culture and the purpose was to find a screening method as a alternative to early animal experimental methods. The established human bone marrow cell culture has certain advantages when compared with other cell culture models. The result demonstrated a high conformity with animal experimental results.

Biocompatible Materials↗
PubMedDate not supplied

[Implant fixation strength and osseointegration following systemic administration of recombinant factor XIII and factor XIII concentrate. Animal experiment with implant fixation strength and osseointegration of porous surface implants].

30 cylindrical commercially pure titanium fiber porous coated Ti6A14V implants were inserted press-fit into the proximal humeral portion of 30 sheep humeri to determine the systemic effect of recombinant factor XIII and placenta-derived factor XIII concentrate on bone ingrowth and on strength of fixation. For both the recombinant factor XIII and the factor XIII concentrate group the volume fraction of bone ingrowth and the strength of fixation was higher when compared with the control specimens. However the difference was only significant for the factor XIII concentrate group.

Alloys↗
PubMedDate not supplied

[Standardized infection model for the study of bony ingrowth dynamics of hydroxyapatite-coated and uncoated pure titanium mesh in swine femur].

The authors studied the ingrowth dynamics of bone tissue into the pores of Hydroxyapatite-coated (plasma-spraying technique) and uncoated wiremeshs of pure titanium in an infected implantation site. Samples of the tested materials were implanted into the femora of 15 adult Göttingen minipigs. Just before implantation they were contaminated with Staphylococcus aureus. The animals were sacrificed after 4, 8, 12 and 24 weeks. Undecalcified ground-sections of bone tissue were prepared (app. 100 microns) and stained with toluidine blue for comparative histological evaluation. The HA-coated implants demonstrated advanced new bone formation already after 4 weeks and nearly complete osseointegration after 12 weeks although all samples showed gross and histological signs of persisting infection. Comparable reactions of the uncoated implants could only be observed after 24 weeks. Signs of degradation of the Hydroxyapatite-coating could be seen in contact to soft tissue and were more extensive compared to the behaviour in an uninfected site. The results and possible clinical consequences are discussed.

Animals↗
PubMedDate not supplied

[Established aspects and current knowledge in biomaterials research].

A review of the currently clinically established biomaterials UHMWPE, Al2O3-ceramic, CoCr- and Ti-based alloys and HA-coatings is given on the basis of recognized and new insights. Advantages and disadvantages as well as prospectives (PE-disease, Ti wear, HA-resorption in vivo etc.) are discussed and documented with results from experimental and clinical experience. New surface hardening techniques for Ti-based alloys are mentioned. Experimental results and singular experience from clinical retrieval study of new plastics (PAEK, Triazin-resin) are presented. Composite materials as a basis for a new generation of isoelastic hip prosthesis stems are described at the end of this paper.

Absorption↗