[Preoperative planning in hip endoprosthetics: presenting a computer-assisted system using CAD software]. / Präoperative Planung in der Hüftendoprothetik: Vorstellung eines computergestützten Systems unter Verwendung von CAD-Software.

The implantation of hip prostheses is a complex operation if one takes in consideration the peculiar features of the different types of implants, the knowledge and skill of the surgeon and the differing characteristics of the patients. In particular, biomechanical parameters have to be respected if a good long-term outcome is to be achieved. Normally the planning of the operation is done with colored pencils and tracing paper. In this paper we present a computer-based system for the planning of arthroplasty with which it is possible to obtain precise two-dimensional simulation of the operation after entering the bone contours, as visualized radiographically, into CAD software.

[Alkaptonuria and ochronotic arthropathy. Arthroscopic and intraoperative findings in implantation of a knee joint surface replacing prosthesis]. / Alkaptonurie und ochronotische Arthropathie. Arthroskopischer und intraoperativer Befund bei Implantation einer oberflächenerneuernden Knieendoprothese.

Alcaptonuria is a rare (incidence approx. 1:10(6)), autosomal-recessive transmitted metabolic disease. The basic defect is a lack of the enzyme homogentisic acid oxidase. During metabolism of phenylalanin and tyrosin to fumaric acid and acetoacetic acid this enzymatic defect causes an accumulation of the intermediate breakdown product homogentisic acid in bradytrophic tissues resulting in pigmentation and calcification of the intervertebral disks. We present a 57 year old female patient in whom we diagnosed alcaptonuria by the appearance of the typical symptom trias homogentisic acid excretion in the urine, ochronosis and arthritis. The anamnesis and results of a knee arthroscopy, radiographic and laboratory examinations as well as the intraoperative and histological findings during implantation of a knee joint surface replacing prosthesis (Gemini-System, Link Co., Hamburg, Germany) are reported.

Effects of membrane lipid and fluidity modifications on HIV-1 infectibility of primate lymphocytes in vitro.

Although most non-human primates, except the chimpanzee and the gibbon in vivo are not infectible by HIV-1, lymphocytes of several of these species can be infected by HIV-1 in vitro. In order to investigate whether the in vitro infectibility of primate lymphocytes might be attributed to plasma membrane adaptation processes or to serum factors, we compared HIV-1 infectibility of cultivated peripheral blood lymphocytes of macaques and of baboons on day one and on day ten of cultivation. These data were correlated to plasma membrane lipid composition and membrane fluidity. We found a correlation between increased HIV-1 in vitro infectibility and changes in plasma membrane lipid composition resulting in decreased membrane fluidity of cultured primate lymphocytes.