Fine structure of ependymal cells in the median eminence of the frog and mouse revealed by freeze-etching.

Freeze-etched preparations of the ventricular surfaces of ependymal cells clearly reveal the presence of pinocytotic vesicles opening into the third ventricle and large vacuoles formed by broad cell projections. The density of the vesicular openings is approximately 20 per micron2. The ependymal cells in the median eminence of the frog are adjoined by tight junctions comprised of five to eight interconnected junctional strands, whereas near the median eminence in the mouse only one to two such strands form the tight junction of the ependymal cells.

Cytological evidence for different types of cerebrospinal fluid-contacting subependymal cells in the preoptic and infundibular recesses of the frog.

Blue-green fluorescent subependymal cells with intraventricular processes were shown by the fluorescent histochemical method to be distributed from the preoptic recess to the infundibular recess of the frog hypothalamus. Electron microscopy revealed at least two types of CSF-contacting subependymal cells, type 1 containing large dense granules (about 100-200 nm in diameter) and type 2 containing small dense core vesicles (about 60-100 nm in diameter). Subsequent to fixation in permanganate solution, the small dense core vesicles in type 2 cells reacted with the fixative and consistently showed a dense content.

Fine-structural and functional aspects of the cerebrospinal fluid-contacting subependymal cells in the anuran hypothalamus.

Cytological characteristics of the cerebrospinal fluid (CSF)-contacting subependymal cells in the frog hypothalamus were investigated to decide whether they should be classified as neurons, sensory cells or secretory (endocrine) cells. The CSF-contacting subependymal cells exhibited morphological characteristics similar to neurons or sensory cells, which are usually supplied with axo-somatic and -dendoritic synapses from other neurons and possess somato-dendritic synapses to other neurons. Furthermore, they were provided with so-called sensory cilia.

Resistance mechanism of chloramphenicol in Streptococcus haemolyticus, Streptococcus pneumoniae and Streptococcus faecalis.

The chloramphenicol resistance of Streptococcus haemolyticus, Streptococcus pneumoniae and Streptococcus faecalis isolated from clinical materials was proved to be due to an inactivating enzyme produced by these bacteria. The inactivated products of chloramphenicol were identified as 1-acetoxy, 3-acetoxy and 1,3-diacetoxy derivatives by thin-layer chromatography and infrared spectroscopy. The responsible enzyme was thus confirmed to be chloramphenicol acetyltransferase.

[Bacteriological studies on doxycycline (Bonnamycin 'Cipan') (author's transl)].

Bonnamycin which is a new tetracycline group antibiotic isolated from a variant strain of Streptomyces rimosus and is identified chemically as doxycycline was investigated, comparing with tetracycline. The results are as follows: (1) In in vitro studies of anti-bacterial spectrum, doxycycline is widely effective against standard strains kept in our department. (2) The distribution of susceptibility of 75 Staphylococci, 62 Salmonella and 64 Shigella strains isolated from clinical materials was similar to that of tetracycline.