First inventory of resorption lacunae on rods and plates of trabecular bone as observed by scanning electron microscopy.

In the present study a novel systematic distribution scheme of resorption lacunae (RL) was applied using scanning electron microscopy. RL, classified as either reticulate patch resorption lacunae (RPR) or as longitudinally extended resorption lacunae (LER) [11, were analyzed and quantified according to their localizations on rods (middle, nodes or both) and plates (central or peripheral) in standardized segments from the femoral head of 24 Caucasian subjects without bone disease. Age and gender variations were explored. No clear gender-related distribution pattern could be detected on plates. On rods of males, however, the distribution of RL tended to be higher at the nodes, but seemed to be more prevalent in the middle or extended from the middle to the nodes of rods in females. Certain other non-conclusive tendencies in relation to age, gender, type of RL and localization were observed.

Microstructural classification of resorption lacunae and perforations in human proximal femora.

Resorption lacunae and perforation types mirror resorptional activity of osteoclasts and are important for the integrity of bone architecture. In the present study, distinctive microstructural features of cancellous bone dissected from femoral heads of 28 autopsy subjects (14 females and 14 males) were defined and evaluated by light microscopic (LM) histology and scanning electron microscopy (SEM). The work differentiates two types of resorption lacunae in trabecular bone: the longitudinally extended resorption lacunae (LER) and the reticulate patch resorption lacunae (RPR). Further, two types of perforations are distinguished: the lacunar perforation (LP) and the tunneling perforation (TP), which are differentiated from potential blood vessel canals (BC). Evidence is presented that the spatial distribution on rods or plates is highly correlated with the resorption type. The RPR type was more frequently seen and was primarily localized at the nodes of rods, in the middle regions of rods, and in the center region of plates as compared to the LER type. The presented evaluation scheme of resorption and perforation types could prove useful in future studies for systematically investigating potential microstructural changes associated with disturbed bone turnover.

[cDNA array approach to cytokine expression profile of aseptic loosened hip arthroplasty]. / cDNA-Arrays Zytokin-Expressionsprofil aseptisch gelockerter Femurschaftprothesen.

FACTS: Aseptic loosening of hip arthroplasties are the main reason for revision operations. Basic research indicates a significant relevance of the interface membrane formed between the implant an the surrounding bone. Their cellular composition and the influence of various factors on the process of aseptic loosening has attracted scientific interest. Cytokines are essential for intracellular communication. QUESTION: Is it possible to reveal differences in the expression profile of cytokines between well-fixed and failed hip arthroplasties using the cDNA array approach? AIM. Generation of a cytokine expression profile characteristic for failed hip arthroplasty. METHODS AND RESULTS: Radioactively labeled cDNA probes were synthesised from mRNA isolated from the interface membrane of six patients with aseptic loosened hip arthroplasty. Using a phosphorimager the analysis of the cDNA arrays revealed nine cytokines which were overexpressed compared with the reference tissue (Calgranulin A, Calgranulin B, IL-10, MCP-1, RANTES, TFDG1, TNFR2, RAI, THYB10). CONCLUSION: In this study four out of these nine cytokines were found to be connected with the process of aseptic loosening for the first time.

Structure and localization of cyclosporin synthetase, the key enzyme of cyclosporin biosynthesis in Tolypocladium inflatum.

The electron microscopic image of native cyclosporin synthetase molecules showed large globular complexes of 25 nm in diameter, built up by smaller interconnected units. Compartmentation of cyclosporin synthetase and the functionally interconnected D-alanine racemase was revealed after sucrose density gradient centrifugation of subcellular fractions and immunoelectron microscopy. A considerable proportion of cyclosporin synthetase and D-alanine racemase was detected at the vacuolar membrane. The product cyclosporin was localized in the fungal vacuole.