Shika Kiso Igakkai zasshi = Japanese journal of oral biology最新文献

The morphology of the incisive suture (InS) in mice was studied using specimens stained with alizarin red S. Formation of this suture was also studied histologically with light microscopy. The InS is composed of three regions; the 1st and 2nd are short and well interdigitated regions respectively situated on the inside and the outside of the anterior palatine foramen. The 3rd region is a loose curved region situated on the outside and the nasal cavity side of the cranium. The InS surrounds the posterior region of the incisors in the upper jaw with a ring-like form. The InS is formed in four steps; cell aggregation (19 days postconception and one day postpartum), formation of bone extensions and collagen fiber bundles (4 and 7 days postpartum), modification of the orientation of these fiber bundles (14 days postpartum), and formation of the serrated suture and fiber bundles with regular orientation (21, 30 and 60 days postpartum). Furthermore, the distance between the bones in the InS was found to be from 40 to 60 microns. The morphology of the InS indicates that it functions as a strong connection between bones, and as a buffer zone. These functions of the InS seem to correspond closely with the function of the incisors in the upper jaw.

The involvement of GTP-binding protein in inositol phospholipid metabolism in guinea pig peritoneal exudate macrophages stimulated with the chemoattractant N-formyl-Methionyl-Leucyl-Phenylalanine (fMLP) was examined. The GTP analog, guanosine 5'-[gamma-thio]triphosphate (GTP gamma S) caused a dose-dependent increase in the formation of inositol triphosphate in membranes of macrophages. This effect was specific for GTP and its analog. fMLP-induced inositol phospholipid turnover was markedly inhibited by the prior exposure of macrophages to 100 ng/ml of pertussis toxin (PT). Likewise, the pretreatment of macrophages with 100 ng/ml of PT evoked the inhibition of the increase in the intracellular free Ca2+ concentration and the spreading of macrophages induced by fMLP. These actions of PT were not associated with an alteration in the cellular concentration of cyclic AMP. Incubation of the membranes of macrophages with [32P]NAD and PT resulted in the ADP-ribosylation of a 41,000 Da protein. This ADP-ribosylation was diminished by the prior incubation of the membranes with 100 microM GTP gamma S plus 1 mM MgCl2, indicating that the 41,000 Da protein may be the alpha subunit of a GTP-binding protein. Moreover, there was a parallel between the time course of the ADP-ribosylation of intact macrophages by PT and the inhibition of the increase in intracellular free Ca2+ concentration as well as of the enhancement of the spreading of macrophages. These results suggest that the 41,000 Da protein, a GTP-binding protein, mediates the fMLP-stimulated inositol phospholipid metabolism.

The cytoskeletal structures in the apical region of mouse taste bud cells were examined by immunocytochemistry and electron microscopy. Immunostaining for actin showed positive reactions in the apical portions of the taste buds. These regions contained bundles of longitudinally oriented filaments (5-7 nm in diameter) extending from the tip of microvilli to the apical cytoplasm of type I, II, and III cells. After incubation with heavy meromyosin, arrowhead formation was observed along these filaments, thus indicating these filaments to be composed of actin. The plasmalemmal undercoat, which was composed of vertical and horizontal layers, was observed on the zonula occludens. It is supposed that this undercoat gives the structural support for the lateral membrane of the apical region in the taste bud cells.

Lingula unguis shell yields a diffuse small angle X-ray scattering which is caused mainly by the scattering from particles of apatite. In this study, the distribution of particles smaller than 500A was analyzed using the small angle X-ray scattering technique. The non-linear Guinier plot indicates that the shell contains various sizes of apatite particles ranging about 20-460A. The small granules with size about 20-160A in diameter are located in the marginal part of the shell and progressively larger granules are observed internally towards the central part. The scattering is anisotropic in the lateral and central part, where the apatite crystals highly ordered. The combined analysis of wide and small angle diffraction indicates that the particles are elongated in the c-axis direction and, furthermore, their long axes are arranged almost parallel to the direction of growth in these parts. This suggests that small and isotropic particles are formed in the early stage of mineralization and larger ellipsoidal shaped particles are formed in the later stage of mineralization.

It is well known that periapical pathosis is one of endogenous infections caused by indigenous bacteria in the oral cavity. Therefore, interaction of host and parasite factors affect the progress of the lesion. In host factors, fibroblasts migrate chemotactically, proliferate and constitute new connective tissues at a late stage of the inflammation process. All of chemoattractants for fibroblasts previously reported are derived from the host. In this study, fibroblast chemotactic activities in bacteria isolated from chronic periapical pathosis cases were examined. Fibroblast chemotactic activity was measured by the membrane filter method using cultured guinea pig dermal fibroblasts. Fibroblast migration was activated by bacterial supernatants of 4 species among 45 species tested. This indicates the possibility that these bacterial factors as well as host derivatives such as fibronectin, lymphokine, collagen-, elastin- and platelet-derived factors, may exert an influence on the process of periapical pathosis. The supernatant from Succinivibrio dextrinosolvens showed the most intensive chemotactic activity, which were separated into two fractions by Sephacryl S-300. The active fraction having a lower molecular weight (Mw. ca. 280K) did not absorb on DEAE-Sepharose CL-6B and this activity was resistant to heat and proteolytic enzymes.

A piece of minor salivary gland tissue obtained from the lip of a 16 years old female was minced to about 3 mm3 by fine pincettes and cultured with 10% FCS containing MEM supplemented with EGF (10 ng/ml), fungizon (10 mcg/ml) and kanamycin (60 mcg/ml) in a 5% CO2 incubator. Many small bubbles of saliva were found on the surface of the fragments after 3 to 4 days of incubation and outgrowth of cells from the fragments was observed from 7 days of incubation. Monolayer cells of the outgrowth were trypsinized and passaged with fresh culture medium. At the 8th passage, monolayer cells were infected with SV40 at moi 100PFU/cell. After 18 hour-incubation, the suspension of the infected cells was incubated at densities of 10(4) and 10(3) cells/dish within 0.33% agar containing culture medium. Transformed colonies were picked up from soft agar medium and 3 of the 28 colonies were identified as being acinar cells of the salivary gland, since secretory granules and mucosubstances were specifically proved in the cytoplasm of these cells after 2 to 4 days of incubation. One of the typical clone cells was named HA-16 cells. However, the appearances of the secretory granules and mucins in the cytoplasm of the HA-16 cells depended on the cellular growth cycle, i.e. secretory granules and mucins were not found in the growing cells (G1-S-G2-M phase) but many secretory granules and mucins could be recognized in the non-dividing cells (G0 phase).(ABSTRACT TRUNCATED AT 250 WORDS)

The relation between the cytoskeleton and multiplication of cultured endothelial cells was observed immunocytochemically and electron microscopically. Heparin and protamine were used to control the multiplication of the cells. Cytochalasin D, a microfilament synthesis inhibitor, was also used, and its effect on cytoskeletal morphology was compared with the effect of heparin or protamine. In order to quantify changes in microfilaments, the ratio of the length of microfilaments to that of intermediate filaments (M/I ratio) was measured by transmission electron microscopy of the whole mounted cells. The addition of heparin to the culture medium not only enhanced multiplication of the endothelial cells, but also induced the outgrowth of many pseudopodia. In association with these changes, microfilaments became sparse, and stress fibers became short. The addition of protamine to the culture medium suppressed multiplication of endothelial cells and made them spherical. The thickening of the cytoplasmic layer increased the apparent density of the cytoskeleton, but the M/I ratio remained unchanged. Cytochalasin D made the endothelial cells spherical, and at the same time stress fibers disappeared, and microfilaments became sparse. The M/I ratio was smaller than that of the others. Protamine may inactivate protein which forms bridges to connect microfilaments or which binds microfilaments and the cell membrane.