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Biomedical subjects

M Akai

Publications and source records attributed to M Akai.

At least 55 records · Page 3Linked to original sources
PubMed1990

Influence of colchicine on the addition of a sugar to the enamel protein in secretory ameloblasts of cultured germs of rat molar tooth by 3H-galactose radioautography.

The influence of colchicine on the addition of 3H-galactose to the enamel protein in secretory ameloblasts of cultured germs of rat molar tooth was investigated by light- and electron-microscopic radioautography. In tooth germs cultured without colchicine, the reaction products of 3H-galactose were observed over Golgi cisternae at early chase times and then localized over the enamel with time. In tooth germs cultured with colchicine, the silver grains were seen over the Golgi cisternae, condensing granules and accumulated secretory granules. Some grains also appeared with time over the pale granular material precipitated in the intercellular space with colchicine treatment. In quantitative analysis with light microscopic radioautography, values of silver grain counts over the unit area (100 microns2) on ameloblasts and enamel of colchicine-treated tooth germs were significantly lower at both 0 min and 30 min chase after 30 min pulse than those of control tooth germs, respectively. This finding indicates that colchicine diminished the incorporation of 3H-galactose into the secretory ameloblast of cultured tooth germs. It is suggested that colchicine decreases the activity of the Golgi apparatus with regard to the addition of sugar to the synthesizing glycoprotein in the secretory ameloblast.

Ameloblasts↗
PubMed1990

Effect of direct-current stimulation on the growth plate. In vivo study with rabbits.

Electrical stimulation of 8 microA direct current was applied to the femoral distal growth plate of young rabbits for periods of 1, 2, and 3 weeks to examine the effect on bone growth. The results were analyzed using X-ray measurement, histological observation including tetracycline labeling, and glycosaminoglycans analysis. No obvious differences between the stimulated side and the control side were observed in the morphological and biochemical studies, but characteristic thickening of the growth plate caused by the accumulation of hypertrophic cells was found in the group stimulated for 2 weeks. Electricity affects the cell behavior of the growth plate, but it is necessary to find more appropriate conditions to stimulate obvious bone growth.

Animals↗
PubMed1990

Leucine-enkephalin-, neurokinin A- and cholecystokinin-like immunoreactivities in the guinea pig tongue.

The occurrence of these neuropeptides was examined by immunofluorescence. Leu-Enk-like immunoreactivity was seen in nerve fibres associated with the epithelium, blood vessels and lingual salivary glands as well as in ganglionic cells within the tongue. Neuropeptide A-like immunoreactivity was found in nerve fibres associated with the epithelium, taste buds, blood vessels and lingual salivary glands. Cholecystokinin-like immunoreactivity was found in some nerve fibres around blood vessels as well as in ganglionic cells. The coexistence of these neuropeptides and substance P was also demonstrated in some nerve fibres and ganglionic cells within the tongue. Like substance P, these neuropeptides could be involved in blood flow regulation, salivation and as trophic factors for taste buds.

Animals↗
PubMed1990

Fine structure of calcitonin gene-related peptide-immunoreactive nerve fibres in the rat temporomandibular joint.

The distribution and fine structure of these nerve fibres was examined by immunoelectron microscopy. CGRP-immunoreactive fibres were seen in the nerve bundles, blood vessels and periosteum around the condyle as well as in the disc. These nerve fibres were unmyelinated and had diameters varying from 200 to 600 nm. They were completely or partially enclosed by Schwann cell cytoplasm and did not form synaptic contact with any cells. CGRP-immunoreactive nerve fibres may be sensory nature and this peptide could be involved in pain transmission and neurogenic inflammation.

Animals↗
PubMed1990

The distribution of vasoactive intestinal polypeptides and calcitonin gene-related peptide in the periodontal ligament of mouse molar teeth.

The distribution of VIP- and CGRP-containing nerve fibres was examined by indirect immunofluorescence. There were many such fibres in the lower third of the ligament, some around the blood vessel close to the socket wall. In the middle third of the ligament, some CGRP-containing fibers entered from the lateral wall of the socket; this type of fibre was more numerous in the lower third than in middle third. There were some VIP-containing fibres but no CGRP-containing fibres in the ligament surrounding the furcation of the molar roots.

Alveolar Process↗
PubMed1989

Carbonic anhydrase activity in the trigeminal primary afferent neuronal cell bodies with peripheral axons innervating the mandibular molar tooth pulps of the rat.

Trigeminal primary afferent neuronal cell bodies were labeled with FITC-WGA retrogradely transported from the mandibular molar tooth pulp (tooth pulp) and the cutaneous branch of the mylohyoid nerve (cutaneous nerve) in the rat. Tissue sections were then incubated in Hansson's medium for histological demonstration of carbonic anhydrase (CA) activity. About 85% of primary neurons innervating the tooth pulp had medium to large cell bodies (greater than or equal to 300 microns 2 in cross-sectional area), while 77% of those innervating the cutaneous nerve were small (less than 300 microns 2). A total of 32% of the tooth pulp cells exhibited CA activity. CA-containing cells constituted only about 4% of the cutaneous nerve cells. In view of the known distribution of CA within the rodent nervous system, the CA-containing cells are considered to represent the tooth pulp primaries conducting in A-beta velocity range and projecting to rostral subdivisions of the brainstem sensory trigeminal nuclear complex.

Afferent Pathways↗
PubMed1989

Peptidergic innervation of the temporomandibular disk in the rat.

The peptidergic innervation of the temporomandibular disk was investigated in the postnatal young rat by using an indirect immunofluorescence method. Calcitonin gene-related peptide-containing nerve fibers were located around the blood vessels and terminated as free nerve endings in the disk. These nerve fibers may be of a sensory nature.

Aging↗
PubMed1989

Localization of two distinct acid phosphatases in secretory ameloblasts of rat molar tooth germs.

Acid phosphatases were examined histochemically at the light- and electron-microscopic levels using para-nitrophenyl phosphate (pNPP) and beta-glycerophosphate (beta-GP) as substrates. By light microscopy, there was intense activity with pNPP in supranuclear and distal regions of the secretory ameloblast, and moderate or slight activity respectively in those regions with beta-GP. These enzyme activities were less at the late secretory stage of amelogenesis and disappeared at the transitional stage. By electron microscopy, acid phosphatase activity was seen in the trans side cisternae of the Golgi apparatus, in lysosome-like granules, and in small vesicles in the Tomes' processes. The activity with pNPP but not beta-GP was also localized at the plasma membrane (proximal, lateral and distal surface). Activity with beta-GP was completely inhibited by 1 mM sodium tartrate and by 1 mM NaF; activity with pNPP was inhibited by 1 mM NaF and 10 mM sodium tartrate, but not by 1 mM sodium tartrate. Thus there are at least two different acid phosphatases, one tartrate-sensitive and the other 1 mM tartrate-resistant, in the secretory ameloblast; the tartrate-resistant enzyme is plasma-membrane bound.

Acid Phosphatase↗
PubMed1989

Immunohistochemical observation on neuropeptides around the blood vessel in feline dental pulp.

Recent advances in immunohistochemistry have revealed the distribution of various neuropeptides in several mammalian dental pulps. These neuropeptides are substance P, neurokinin A, calcitonin gene-related peptide, vasoactive intestinal polypeptide, and neuropeptide Y. Nerve fibers showing immunoreactivity for these neuropeptides are mainly localized around the pulpal vessels, but some are apart from the blood vessel. The distribution of substance P-, neurokinin A-, and calcitonin gene-related peptide-containing nerve fibers is very similar; it appears that these three neuropeptides may be contained in the same nerve fibers. Denervation experiments indicate that substance P-, neurokinin A- and calcitonin gene-related peptide-containing nerve fibers originate from the trigeminal ganglion and that neuropeptide Y-containing nerve fibers come from the superior cervical ganglion. However, the exact origin of vasoactive intestinal polypeptide-containing fibers still remains unknown. These immunohistochemical data indicate that neuropeptides localized around the blood vessel may play a significant role in the regulation of the blood flow in the dental pulp.

Animals↗
PubMed1989

Histochemical localization of calcium in the enamel organ of rat incisors in early-stage amelogenesis.

The localization of calcium in the enamel organ of rapidly-frozen, freeze-substituted rat incisors in early-stage amelogenesis was examined by a histochemical calcium-staining method. In secretory ameloblasts, glyoxal bis(2-hydroxyanil) (GBHA) staining revealed intense red reactions in mitochondria and tubulovesicular structures located throughout the cytoplasm, while no reaction was seen in the nucleus and cytosol, nor along the plasma membranes of the respective cells. No significant GBHA reaction was observed in the intercellular compartment and other cells of the enamel organ. Some granular reactions were localized in the cells of the adjacent connective tissue. Control tests confirmed the specificity of GBHA reactions for calcium. Thus, the present observations provide histochemical evidence indicating an exclusive localization of calcium in mitochondria and tubulovesicular structures of the secretory ameloblast, and support their contributions to the translocation of calcium from the proximal to the distal pole of the cytoplasm.

Amelogenesis↗
PubMed1988

Effect of colchicine on the transport of precursor enamel protein in secretory ameloblasts studied by 3H-proline radioautography in vitro.

The incorporation of 3H-proline into the secretory ameloblasts of rat molar tooth germs cultured with or without colchicine was studied by light and electron microscope radioautography to determine the function of microtubules in the transport of precursor enamel protein from the rough-surfaced endoplasmic reticulum (rER) to the Golgi cisternae. The grain counts over the transitional vesicles, which accumulated in various cellular regions with colchicine treatment, continued to increase with chase time, unlike in controls. At 30 and 90 min chase, these counts were significantly higher than in controls. Moreover, the total grain count over the organelles (rER, pale granules, and transitional vesicles), which are positioned before the Golgi cisternae in the synthetic pathway, maintained a significantly higher level at 90 min chase in colchicine-treated tooth germs than in controls. The transport of synthesized protein to the Golgi cisternae via transitional vesicles was suppressed in colchicine-treated tooth germs. Some grains appeared with time over pale granular materials that appeared in the intercellular spaces of secretory ameloblasts with colchicine treatment. However, at each chase period, the grain count over pale granular materials was not so high as the count over the enamel in control. The present results indicate that colchicine affects the transport of newly synthesized protein from the rER to the Golgi cisterna via transitional vesicles, probably by interfering with the oriented transport related to microtubular function. It is suggested that the microtubular system may be concerned with the movement of the transitional vesicles.

Ameloblasts↗
PubMed1988

Budding of small vesicles from the rough-surfaced endoplasmic reticulum in secretory ameloblasts of rat molar tooth germs.

The budding of small vesicles from the rough-surfaced endoplasmic reticulum (rER) was examined in the secretory ameloblast of rat molar tooth germs by ordinary fixation or prolonged osmium fixation. The budding of small vesicles from the rER was observed not only at the special region (transitional region) of the rER system, which abutted on the cis-face of the Golgi apparatus, but also at other regions of the rER in the secretory ameloblast. Small vesicles (presumed to be transitional vesicles) were adjacent to the rER, which also showed budding of vesicles. After prolonged osmium treatment, osmium deposits appeared in small vesicles, as well as in the cisternae of the cis saccule of the Golgi apparatus. Small vesicles containing osmium deposits were located at various regions of the cell, including the cis-face of the Golgi apparatus. These findings indicate that the budding of small vesicles from the rER is not restricted to the transitional region of the rER system of the secretory ameloblast, but is found at various regions of the cell. This indicates that newly synthesized proteins may be transferred from the rER cisternae to the transitional vesicles not only in the transitional region of the rER system adjacent to the Golgi apparatus, but also in other regions of the secretory ameloblast.

Ameloblasts↗
PubMed1988

Neurokinin A-like immunoreactivity in feline dental pulp: its distribution, origin and coexistence with substance P-like immunoreactivity.

The distribution and origin of neurokinin A (NKA)-like immunoreactivity were investigated in feline dental pulp by an indirect immunofluorescence method. NKA-containing nerve fibres with varicosities, which entered the dental pulp via apical foramen, were distributed throughout this tissue. Many NKA-containing nerve fibres were localized around blood vessels, but some were observed apart therefrom. At the odontoblastic layer, thin NKA-containing nerve fibres were observed running straight toward the pulp-predentinal border between odontoblasts. After inferior alveolar nerve section, all NKA-containing nerve fibres disappeared in the dental pulp, while the removal of the superior cervical ganglion resulted in no change in the distribution of these fibres. The correlation of NKA-like immunoreactivity and substance P (SP)-like immunoreactivity was also investigated by double-immunofluorescence technique. The distribution of NKA-containing nerve fibres was very similar to that of SP-containing nerve fibres; it appeared that all NKA-containing nerve fibres contained SP.

Animals↗
PubMed1988

Histochemical, ultrastructural and X-ray microprobe analytical studies of localization of calcium in the mucous lining of the rat duodenum.

Localization of calcium in a rapid frozen and freeze substituted duodenum of normal, starved or calcium-repleted rat was examined using either of the glyoxal bis(2-hydroxyanil) (GBHA) staining method, a sensitive histochemical calcium stain or electron microscopy. In normally-fed rats, a majority of absorptive cells of the duodenum showed numerous discrete red granular GBHA reactions, approximately 1 micron or less in diameter, located primarily along their lateral plasma membranes and within intercellular spaces. Electron microscopy also revealed electron-dense granules, 30-100 nm in diameter, showing a similar distribution as the GBHA granules in the respective absorptive cells, and confirmed their absence in mitochondria and other intracellular compartments. Some of the absorptive cells located exclusively at the tip of each villus contained highly GBHA-reactive tubulo-vesicular structures extending throughout the cytoplasm. However, they displayed virtually no granular GBHA reaction. In these cells, electron microscopy revealed numerous electron-dense granules in the nucleus, mitochondria and in other unidentified organelles. X-ray microprobe analyses of ultrathin sections confirmed the presence of calcium within electron-dense granules associated with both types of absorptive cells. The number and intensity of all GBHA reactions fluctuated according to luminal calcium concentration. In calcium-repleted rats, strong GBHA reactions appeared in a narrow zone of lamina propria at the tip of the villus, overlaid, predominantly, with absorptive cells showing tubulo-vesicular GBHA reactions. These results suggest the existence of distinct types of absorptive epithelial cells in the rat duodenum, with respect to patterns of calcium localization which they display.

Aminophenols↗
PubMed1988

Cyclic changes in the properties of maturing enamel in the bovine permanent incisor as revealed by glyoxal bis(2-hydroxyanil) staining.

Staining patterns of the surface and interior of maturing enamel of these tooth germs were examined using the glyoxal bis(2-hydroxyanil) (GBHA) solution which chelates with calcium loosely bound to hydroxyapatite to form insoluble red precipitates. An intense red, band-like pattern of GBHA staining, 1-2 mm wide, first appeared on the incisal portion of lingual enamel surface as complete loops, concentrically arranged; these gradually increased in number. Most of the later-formed bands encircled the entire periphery of the maturing enamel surface. GBHA also revealed reactive areas on the labio-lingual, cut and ground surface of maturing enamel, corresponding exactly to the surface GBHA bands. GBHA did not stain EDTA-etched surface enamel, but did reveal regular staining patterns on the ground surface, disclosed after EDTA treatment. These observations suggest an intimate correlation between the properties of interior and surface enamel, at least with regard to the state of local calcium. The maturation of bovine incisor enamel may start at the lingual aspect of the tooth crown.

Aminophenols↗