The purpose of this study was to improve the pathogen detection in prosthetic joint infections, particularly to evaluate the feasibility of the sonication culture method in the clinical routine. Explanted components of all patients with presumptive prosthetic or implant infection were sonicated separately in sterile containers to dislodge the adherent bacteria from the surfaces and cultured. The results of sonication culture were compared to the conventional tissue culture. We investigated 60 consecutive patients with loosening of the prostheses or implants Forty patients had septic and 20 aseptic loosening (24 knee prostheses, 21 hip prostheses, 6 mega-prostheses, 2 shoulder prostheses, 6 osteosynthesis, 1 spinal instrumentation). The sensitivity of sonication fluid culture was 83.3%, of single positive tissue culture was 72.2% and 61.1% when two or more cultures yielded the same microorganism. In patients receiving antibiotic therapy the sensitivity was 65.9%, 57.5%, and 42.5%, respectively. Pathogens detected in a single tissue culture as well as in sonication culture yielded a significantly higher rate of prosthetic infection than conventional tissue culture alone ( p ¼ 0.008), even in patients receiving continuous antibiotic therapy before explantation ( p ¼ 0.016). The sonication method represents an essential add-on in pathogen detection compared to conventional tissue culture. ß

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The localization of thiolacetic acid esterase activity in plasmodia of the slime mold, Physarum conferturn Macbr., permitted the visualization of a system of esterolytic invaginations of the plasma membrane which appeared closely related to the arrangement of fibrillar structures. Fibrils running perpendicularly to the long axis of tubes and channels of the conducting system were found to be attached tcr relatively large lateral infoldings, while rows of smaller invaginations seemed to follow the course taken by the fibrils. In living and &xed specimens, constrictions in the diameter of tubes and channels were observed at the level of fibrils and linearly arranged rows of infoldings. These findings suggest that esterase-positive infoldings may result from the contraction of fibrillar structures which are attached to the plasma membrane at multiple points along their length.Acellular slime molds are presently much investigated in studies of cytoplasmic streaming. The plasmodial stage of these primitive organisms may be likened to a large multinucleate ameba in which the cytoplasm temporarily assumes various degrees of gelation so as to provide a system of semi-rigid channels conducting a mobile sol phase. Cytoplasmic flow within the conducting system can be observed to change direction rhythmically and is presently believed to be caused by differences in hydraulic pressure within the plasmodial sheet (Kamiya, 50; Kamiya and Kuroda, '58; Jahn et al., '64; Jahn, '64), while the pressure is presumed to be generated by the contraction of fibrillar structures ( Wohlfarth-Bottermann, '62, '64a; Nakajima and Allen, '65).The first histochemical support for the current contraction theories of cytoplasmic streaming was the demonstration of ATPase activity associated with ultramicroscopic filaments in plasmodia of the slime mold, Physamm polycephalum ( Wohlfarth-Bottermann, '64b). In search of further histochemical evidence of contraction in slime mold plasmodia we were guided by reports in the literature on esterase activity in regions where contractile structures terminate near or in the plasma membrane. E. g., non-specific esterase activity has been demonstrated J. EXP. ZOOL., 164: 69-80.at the level of the intercalated disc of cardiac muscle (Karnovsky and Hug, '63) and acetylcholinesterase has been found in the cell membrane of skeletal muscle fibres at the musculotendinous junction (Couteaux, '53; Schwarzacher, '61) and the cell membrane of the ciliate, Tetrahymena gekii (Seaman, '51). Since fibrillar elements have been shown to be attached to the plasma membrane in slime mold plasmodia ( Wohlfarth-Bottermann, '62) we undertook the present study in the hope of finding a pattern of esterase distribution that could be interpreted in the light of the proposed contractile mechanisms for the generation of protoplasmic flow in these organisms.Non-specific esterases (Wachstein et al., '61) as well as cholinesterases (Wilson, '59) are known to hydrolyze thiolacetic acid with the formation of acetic acid and hydrogen ...

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