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Biomedical subjects

U Nöth

Publications and source records attributed to U Nöth.

24 records · Page 2Linked to original sources
PubMed1995

Several methods utilized for the assessment of biocompatibility of perfluorochemicals.

An overview is presented on methods used to judge the effect of different perfluorochemicals (PFCs) on functional organ changes. By some of these methods the function of the reticuloendothelial system (RES) after a load with PFC was tested, either globally in form of the clearance of colloidal carbon particles or by a magnetometric method to test the phagocytosing function of macrophages within the liver of rats. An endotoxin test on survival of mice after the combined treatment with lipopolysaccharides of E. coli and PFCs showed the importance of a cumulative effect of multiple factors influencing phagocytosis. Other methods examined the influence of PFCs on lipid peroxidation during reperfusion of the ischemic intestine or on the effects of hyperbaric oxygen on the lung. The half-life (mean dwell time) of PFCs within organs with a high storage rate could optimally be determined by means of 19F magnetic resonance imaging in longitudinal studies within the same animal. An influence of PFCs on hepatocytes was tested by determining the time required for detoxifying pentobarbital as measured by the sleeping time (until reappearance of the righting reflex). By all these tests a strong dose-dependence was found, so that effects observed with a high load may become negligible with smaller dosages.

Animals↗
PubMed1994

Fast 19F-NMR imaging in vivo using FLASH-MRI.

The goal of this study was the development of a method that allows the acquisition of chemical shift selective 19F NMR images within a short measuring time. A train of small tip angle frequency selective pulses, each followed by a dephasing gradient of random strength, was used as a presaturation experiment for the suppression of the unwanted chemical shift components. Imaging was performed after presaturation using a SNAPSHOT-FLASH experiment. The acquisition time for a 64 x 128 image including the presaturation experiment amounted to only 470 ms. The sequence was applied in a 4.7 Tesla magnet to perform a longitudinal pharmacological study on the clearance of perfluoroocytlbromide (PFOB) in the liver and spleen of rats.

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

[Standardized testing of bone implant surfaces with an osteoblast cell culture system. II. Titanium surfaces of different degrees of roughness].

The effect of titanium surfaces with different degrees of roughness on osteoblast proliferation and differentiation was investigated using a standardised cell culture system. Human foetal osteoblasts (hFOB 1.19) were cultured on polished (Ti pol), sandblasted (Ti sb) and sandblasted/heat treated (Ti sb-ht) titanium surfaces for 17 days. Cell culture quality polystyrene (Ps) was used as a control. Cell number and viability were determined for assessment of proliferation. Alkaline phosphatase activity, collagen I and osteocalcin production were measured as parameters for osteoblast differentiation. In the early phase, higher proliferation values were measured on Ti pol. However, on Ti sb and Ti sb-ht higher proliferation was found in the late phase. The activity of the early differentiation marker alkaline phosphatase was higher on Ti pol. No differences were seen for the late differentiation parameters collagen I and osteocalcin. The test system permits the influence of the surface structure on the dynamics of the osteoblast development cycle to be determined. The larger surface area of rough materials leads to an initially delayed, but then prolonged cell proliferation. This model correlates with recent in vivo findings, and confirms the use of rough surfaces for implants in direct contact with bone, even at the cellular level.

Cell Differentiation↗
PubMedDate not supplied

[Standardized testing of skeletal implant surfaces with an osteoblast cell culture system. IV. Specific gene expression during differentiation].

Successful osseointegration of an implant depends on the properties of the material of which it is made. A standardized cell culture system for the assessment of the biological effect of material surfaces has already been described. In the present study, this system has been extended to include the quantitative analysis of the material-dependent osteoblast gene expression. Human foetal osteoblasts (hFOB 1.19) were cultured for 3 weeks on titanium surfaces of varying roughness, and on surfaces of chromium-cobalt-molybdenum alloy (CrCoMo). Using a real time RT-PCR technique, expressions of alkaline phosphatase, collagen 1 and osteocalcin were determined as parameters of osteoblast differentiation. In comparison with CrCoMo, differentiation was accelerated on titanium. While the smooth titanium surface leads to earlier cell growth, the rough surface induces more prolonged and stronger cell proliferation. Our results confirm at the molecular level the excellent clinical biocompatibility of titanium surfaces. The real-time RT-PCR provides a new method for the quantitative assessment of material-dependent osteoblastic differentiation.

Cell Differentiation↗