[Process of regeneration of cementum observed by various fluorescent-labeling methods].

The purpose of this study was to evaluate the effect of various fluorescent-labeling methods on longitudinal information associated with the process of regeneration of cementum after periodontal therapy. Mandibular bilateral premolars and molars in three monkeys were used. Prior to the labeling, experimental periodontitis was surgically produced at the mesial site of each tooth. In four weeks, scaling and root planing were carried out, and time marking was performed by injection of 3 kinds of fluorescent-labeling materials, tetracycline hydrochloride (30 mg/kg), calcein (8 mg/kg), and alizarin complexon (20 mg/kg), intramuscularly. The animals were sacrificed 4 days after the last injection and serial sections without decalcification were prepared. They were examined under a fluorescence microscope and further observed by contact microradiography (CMR) and staining with toluidine blue. According to the observations made by fluorescence microscopy, marked regeneration of the cementum was revealed by each of the 3 labeling agents. Also, the presence of regenerated cementum was supported by the observations by CMR and after toluidine blue staining. In addition, the regeneration of new cementum was shown to start in about 2 weeks after scaling and root planing. Judging from the results of this experiment, the various fluorescent-labeling methods seem to be effective for observing the process of regeneration of cementum.

Human monochromosome hybrid cell panel characterized by FISH in the JCRB/HSRRB.

The human monochromosome hybrid cell panel in the Japanese Collection of Research Bioresources (JCRB) consists of 23 mouse cell clones, each containing a different human chromosome (the Y chromosome is not yet included). The panel is currently distributed by the Human Science Research Resources Bank (HSRRB) in Osaka. In order to determine the state of the human chromosomes and to supply the information to investigators, we characterized the cells by fluorescence in-situ hybridization (FISH) with corresponding human chromosome-specific painting probes, and, in part, by reverse FISH with the hybrid total DNA hybridized onto human metaphase spreads. Here, we report the frequency of intact human chromosomes maintained in each hybrid and the retained subregions of corresponding human chromosomes with relative frequencies estimated by fluorescent intensity. We used specific painted patterns to classify each hybrid into tentative types with their frequencies showing the nature of each hybrid and the state of rearrangements. This characterization will provide valuable information to investigators using the panel.