[Soft-tissue management in primary knee arthroplasty: common techniques, navigation and force-sensing devices]. / Weichteilmanagement in der primären Kniegelenkendoprothetik: konventionelle Techniken, Navigation und sensorintegrierte Messsysteme.

Soft-tissue management is essential for the outcome in total knee arthroplasty. In combination with osseous resections and component positioning, correction of the underlying ligamentous dysbalance should yield a stable joint throughout the flexion arc. Different "philosophies" with regard to technique, timing and tactics in ligament balancing are described. So far, surgeons have not been provided with standardised devices that allow the objective measurement of this complex issue. Moreover, knowledge concerning the "ideal" soft-tissue stability following knee arthroplasty is still sparse. As part of the scientific project "OrthoMIT" (minimal invasive orthopaedic therapy) an approach to combine conventional soft-tissue management with navigation and force-sensing devices should be realized technically. The aim is to develop an instrument for the objective measurement of soft-tissue management in scientific and clinical applications.

A comparison of continuous wave Doppler radar to impedance cardiography for analysis of mechanical heart activity.

The paper compares the data obtained from a continuous wave Doppler radar sensor based on a commercially available microwave motion sensor KMY24 to an impedance cardiograph measured using a Cardiac Output Monitor (Medis Niccomo). Both sensors are used to analyze the mechanical activity of the heart. System parameters, signal content and robustness are discussed.

Perinatal expression of IGFBPs in rat lung and its hormonal regulation in fetal lung explants.

To gain more insight into the regulation of the expression of insulin-like growth factor (IGF) binding proteins (IGFBPs) in the lung, the developmental patterns of the abundance of the mRNAs encoding IGFBPs were measured in the perinatal rat lung and in explant cultures of fetal rat lung. In hormone-free explant cultures, the levels of the mRNAs encoding IGFBP-2 through -5 changed with a pattern similar to that occurring in vivo (although in the case of IGFBP-3 to -5 at a faster rate), indicating that the developmental regulation of the expression of these IGFBPs in perinatal lung is mimicked in the explants. For the IGFBP-6 mRNA level, the pattern in vitro differed from that in vivo. In the explant cultures, dexamethasone decreased the production of IGFBP-3 and -4 and decreased the abundance of the mRNAs encoding IGFBP-2 to -5 but increased the abundance of IGFBP-6 mRNA. These observations indicate that glucocorticoids may be involved in the developmental regulation of the expression of these components of the IGF system and that the IGF system may be involved in the physiological effects of glucocorticoids on lung development. No appreciable effects of 3,3',5-triiodothyronine on the expression of the IGFBPs were observed.

Ontogeny of surfactant proteins and lipid-synthesizing enzymes in cultured fetal lung epithelial cells.

Fetal rat lung epithelial cells were isolated on gestational day 17 (term is 22), separated from fibroblasts, and cultured up to 6 days in a serum-free medium on a basement membrane matrix. Surfactant protein (SP) A, barely detectable by immunostaining at the beginning of the culture, considerably increased in cells and subsequently in the lumen of the epithelial cell clusters. SP-A mRNA, already detectable at culture initiation, progressively increased. By contrast, SP-B and its mRNA appeared after 2-3 days. SP-C mRNA appeared only after 4 days of culture. Cells cultured 6 days had a phospholipid composition similar to that of freshly isolated adult rat type II cells. The enhancement of lipid synthesis between the first and the sixth culture days, reported earlier to occur in these cells, was found to be accompanied by a two- to fivefold increase in amount of mRNAs of lipogenic enzymes and choline phosphate cytidylyltransferase. In conclusion, alveolar epithelial type II cells appear to be capable of full differentiation in vitro, and components of the surfactant system are all regulated developmentally at a pretranslational level.

Phospholipid-transfer proteins and their mRNAs in developing rat lung and in alveolar type-II cells.

Gene expression of non-specific lipid-transfer protein (nsL-TP; identical with sterol carrier protein 2) and phosphatidylinositol-transfer protein (PI-TP) was investigated in developing rat lung. During the late prenatal period (between days 17 and 22) there is a 7-fold increase in the level of nsL-TP and a 2-fold rise in that of PI-TP. The prenatal increases in the levels of nsL-TP and PI-TP are accompanied by parallel increases in the levels of their mRNAs, indicating pretranslational regulation. Compared with whole lung, isolated alveolar type-II cells are enriched in nsL-TP and its mRNA, but not in PI-TP and its mRNA. The observation that the levels of nsL-TP and its mRNA in rat lung show a pronounced increase in the period of accelerated surfactant formation, together with the observation that the surfactant-producing type-II cells are enriched in nsL-TP and its mRNA, suggest that nsL-TP plays a role in the metabolism of pulmonary surfactant.

Pre-translational regulation by glucocorticoid of fatty acid and phosphatidylcholine synthesis in type II cells from fetal rat lung.

Exposure to fibroblast-conditioned cortisol-containing medium increased fatty acid synthase activity and fatty acid synthase, acetyl-CoA carboxylase and ATP citrate lyase mRNA abundance in fetal type II alveolar epithelial cells. Both fibroblast conditioning and cortisol in the medium were required for maximal effect on the mRNA levels, indicating involvement of mesenchymal-epithelial interaction in the cortisol effects. The observed effects provide evidence for an earlier hypothesis that increased activity of CTP:phosphocholine cytidylyltransferase in lung tissue caused by glucocorticoid is due to increased fatty acid synthesis. However, evidence suggesting pre-translational regulation of this enzyme by glucocorticoid was also found.

The lung lectin surfactant protein A aggregates phospholipid vesicles via a novel mechanism.

Surfactant protein A (SP-A), a lung-specific glycoprotein, consists of an N-terminal collagen-like domain and a C-terminal domain with a sequence similar to that of several Ca2(+)-dependent lectins. SP-A induces a rapid Ca2(+)-dependent aggregation of phospholipid vesicles. We report here that vesicle aggregation is mediated by Ca2(+)-induced interactions between carbohydrate-binding domains and oligosaccharide moieties of SP-A. This novel mechanism of membrane interactions may be relevant to the formation of the membrane lattice of tubular myelin, an extracellular form of surfactant.

Synthesis and degradation of glycogen by Schistosoma mansoni worms in vitro.

The glycogen stores of adult Schistosoma mansoni worms could be labelled by incubation of the worms, after an initial reduction of their glycogen content, in the presence of [6-14C]glucose. Subsequent breakdown of the labelled glycogen by the parasite revealed that glycogen was degraded to lactate and carbon dioxide. The degradation of glycogen, as compared to that of glucose, resulted in slightly different ratios of these two end-products. This indicates that glycogen breakdown did not replace glucose breakdown to the same extent in all cells and that Krebs-cycle activity was not uniformly distributed throughout the cells of this parasite. Both fructose and mannose could replace glucose as an energy source and the rate of glycogen synthesis from either of these two carbohydrates was higher than from glucose. No indications for glyconeogenesis from C3-units were found. Glycogen metabolism of S. mansoni was not influenced by hormones of the mammalian host. It is regulated by the external glucose concentration and by the level of the endogenous glycogen stores. Studies on paired and unpaired worms showed that no interaction between male and female was necessary for the synthesis of glycogen by female worms.