[Assessing the quality of patients' medical records at the Claudius-Regaud Institute]. / Evaluation de la qualité du dossier du patient a l'institut Claudius-Regaud.

In 1999, the Claudius-Regaud Institute of Toulouse, France, specialized in oncology, set up a workshop in order to assess the quality of its patients medical records. A retrospective evaluation was performed on a 100-chart-sample drawn from all the charts in the institution. Results show that the medical records are subdivised into three parts: medical care, nursing care and imaging. Some of the explored charts show a lack of data, and a certain inconsistency in the charts' organization and in the structure of information was reported. Patient's record is a key to communication between the different care providers in oncology. To improve its quality, efforts will have to be done in restructuring the charts, creating guidelines and training the different caregivers.

Freeze substitution reveals a new model for sporangial cleavage in Phytophthora, a result with implications for cytokinesis in other eukaryotes.

Rapid freezing and freeze substitution (RF-FS) have been used to re-examine the process by which the multinucleate sporangium of the Oomycetes, Phytophthora cinnamomi and P. palmivora, is subdivided into uninucleate zoospores. The results indicate a new model for sporangial cleavage in Phytophthora and suggest that the currently accepted model is based on interpretation of artefacts caused by chemical fixation. The previous model describes cleavage as a two-stage process in which specialized cleavage vesicles first become positioned at the boundaries of each future subdivision and later fuse to compartmentalize the sporangium. RF-FS, however, indicates that cleavage results from the progressive extension of paired sheets of membrane along the future subdivision boundaries. These sheets finally interconnect and subdivide the sporangium. Cleavage vesicles are only evident in preliminary stages of this process and are never aligned along the future boundaries, contrary to the observations of studies based on chemical fixation. Chemical fixation apparently causes the membranous sheets to vesiculate, even at relatively advanced stages of cleavage, thus giving the misleading impression that the resulting network of lined-up vesicles is an intermediate stage in the cleavage process. This finding has wide-ranging implications for the understanding of eukaryotic cytokinesis, because all previous studies that describe vesicle alignment and fusion have relied upon chemical fixation. Other novel features revealed by RF-FS include an extensive extracellular matrix within the sporangium that could be involved in zoospore release, and a trans-Golgi network.

Fluorescence microscopic localization of actin in pollen tubes: comparison of actin antibody and phalloidin staining.

A comparison of actin localization in pollen tubes of Nicotiana has been made using a monoclonal actin antibody and rhodamine-phalloidin (RP). The monoclonal antiactin, based on Western blotting of pollen tube extract, labels a polypeptide at 45 kD that comigrates with muscle actin. A 51-kD unknown protein and three bands less than 45 kD, presumed to be proteolytic fragments of actin, are also observed. Structural observations using this antibody reveal a network of axially oriented strands of microfilaments (MFs). The MFs are distributed throughout the length of the pollen tube except at the very tip, where diffuse staining is usually observed. A similar pattern of MFs is evident after RP staining. When pollen tubes are treated with cytochalasins (CB or CD) cytoplasmic streaming is inhibited, as is tube elongation. Microscopic analysis reveals that the microfilament (MF) pattern is markedly altered; however, the antibody and RP produce different staining patterns. The antibody reveals many MF strands that distribute throughout the tube length and extend into the very tip. In contrast, RP shows mostly a diffuse staining pattern with only a few short clumps of filamentous material. Immunogold labelling of sections of pollen tubes prepared by rapid-freeze fixation and freeze substitution reveals that actin MF bundles are indeed present after cytochalasin treatment. Our results thus question reports in the literature, based on phalloidin staining, asserting that cytochalasin fragments or destroys actin MFs.

Initiation and ontogeny of vesicles in cultured Frankia sp. strain HFPArI3.

Removal of combined nitrogen from the medium of Frankia sp. strain HFPArI3 induced the formation of specialized structures, called vesicles, which are the proposed site of nitrogen fixation. After 5 to 6 h of culture on N-free medium, newly formed vesicles, termed provesicles, arose from the tips of some hyphae. These structures were spherical, phase dark, ca. 1.5 to 2.0 micron in diameter, and were not associated with acetylene reduction (nitrogenase) activity. Provesicles reached their greatest frequency after ca. 24 h of N-free culture. Provesicles increased in size to become mature vesicles which first appeared after 18 to 20 h of N-free culture. They were ca. 2.5 micron in diameter, phase bright, and reached their greatest frequency after 5 to 6 days, at which time nitrogenase activity peaked. Some vesicles eventually became damaged structurally and took on the appearance of ghosts. Transmission electron micrographs revealed an increase in size from provesicle to mature vesicle. Also evident with the micrographs were the presence of a septum between the young provesicle and parental hypha, the presence of glycogen in some young vesicles, the development of internal septations as vesicles matured, and the degradation of cytoplasm and internal septae in ghost vesicles. The extent to which the formation of vesicles is reversible by the addition of NH4+ was investigated. Commitment times of 3.2 and 6.5 h were obtained for provesicles and vesicles, respectively. A concentration-dependent inhibition of nitrogenase by NH4+ was demonstrated. The structure of preexisting vesicles was also affected by addition of NH4+ to the culture medium.