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Biomedical subjects

R Ichikawa

Publications and source records attributed to R Ichikawa.

At least 19 recordsLinked to original sources
PubMed1995

Cerebellum of the adult reeler mutant mouse contains two Purkinje cell populations with respect to gene expression for the N-methyl-D-aspartate receptor channel.

Recent studies have identified five NMDA receptor subunits, which exhibit distinct cellular expressions in the normal rodent brain. The purpose of this investigation is to clarify the molecular-anatomical organization in the cerebellum of the reeler mutant mouse, in which various categories of the Purkinje cells are present as to the cell position and synaptic connectivity. In comparison with the distribution of the inositol 1,4,5-trisphosphate receptor mRNA, a molecular marker specific to the Purkinje cells, the epsilon 1 subunit mRNA of the NMDA receptor channel was found in the adjacent sections to be expressed in a subset of the Purkinje cells. In the rostrocaudal extent, the Purkinje cells expressing the epsilon 1 subunit mRNA were distributed preferentially in the rostral cerebellum, irrespective of the normal and heterotopic positions. In the mediolateral extent, they formed segregated cell clusters, interposed by epsilon 1 subunit mRNA-negative clusters. Hybridizing signals for the zeta 1 subunit mRNA were found in all the Purkinje cell population, whereas those for the epsilon 2, epsilon 3, and epsilon 4 subunit mRNAs were not detected in the cells. These findings suggest that the reeler cerebellum is topographically compartmentalized by two subpopulations of the Purkinje cells, one expressing the epsilon 1 and zeta 1 subunit mRNAs, and the other expressing the zeta 1 subunit mRNA alone.

Animals↗
PubMed1995

Sex differences in the shapes of several parts of the young Japanese face.

For the purpose of studying the sex differences of the human face we collected five separate images, which consist of several parts of the face, from frontal view photographs of 48 male and 52 female college students. We traced outlines of their faces with simple lines (traced items), and made reproductions of the photographs of their eyes, mouth and nose by using a copying machine (reproduced items). The test subjects were 16 males and 8 females. They looked at parts of the face shown in each image, and categorized them individually by judging on their sex. Then, we calculated the percentages of correct judgments (percentage correct) for each image. By comparing the percentage correct between male and female we concluded that the sex of the subjects did not affect the results of their judgments. In the traced items the percentage correct for the face as a whole, which contained the outlines of the eyes, mouth, nose and the lower jaw, was 69%, but it decreased to 61% when the outline of the lower jaw was removed. Hence, the outline of the lower jaw apparently has a characteristic shape easily noticed by males. In the reproduced items the percentage correct was 65% for the eyes, 68% for the mouth and 58% for the nose. The mouth, therefore, has more distinguishing characteristics than the eyes or nose, especially with females. On the other hand, there is no correlation between the percentage correct for the eye, mouth and nose items. Hence, we concluded that the sexual specificity for the shape of the young Japanese face appears on their parts independently.

Adult↗
PubMed1993

Distribution of guanine nucleotide-binding protein in the brain of the reeler mutant mouse.

The localization of a GTP-binding protein (G(o)) in the cerebellar and cerebral cortex and hippocampus of the normal and reeler mutant mouse was immunohistochemically examined using affinity-purified antibody raised against the alpha subunit of G(o). Although the general distribution pattern of G(o)-immunoreactive products in the brain of the normal mouse, i.e., abundant in the neuropil but absent from neuronal cell bodies, is also seen in the reeler brain, some differences are present, as described below. Strong G(o)-immunoreactive products are found in the molecular layer of the cerebellar cortex of the normal mouse. In the reeler cerebellum, in addition to the strong G(o)-immunoreactivity of the thin molecular layer, moderate G(o)-immunoreactivities are also found in the granular cell layer and the central cerebellar mass. G(o)-immunoreactive products are distributed throughout all layers of the cerebral cortex of the normal and reeler mouse. However, layer I of the normal cerebral cortex is more strongly stained with this antibody than the underlying layers, whereas the upper third of the reeler cerebral cortex is more strongly stained than the lower two-thirds. In the hippocampus of the normal mouse, G(o)-immunoreactive products are localized in the neuropil of the stratum oriens, stratum radiatum and stratum lacunosum-moleculare, but absent from the cell bodies of the pyramidal cells and their apical dendritic shafts. Such a distribution pattern of G(o)-immunoreactive products is also seen in the hippocampus of the reeler mouse, except that G(o)-immunonegative pyramidal cells split into 2 or 3 laminae.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Abnormal synaptic architecture in the cerebellar cortex of a new dystonic mutant mouse, Wriggle Mouse Sagami.

The 'Wriggle Mouse Sagami (WMS)' is a new neurological mutant with severe dystonic movements of the trunk and extremities whose pathological characters are transmitted by an autosomal recessive gene (wri). Manifestations first appear at 10 days to 2 weeks after birth and progress until 12 weeks of age. In spite of the severe dystonic movements, no marked abnormalities had been found in the cyto- or myeloarchitecture of the central nervous system or that of the peripheral nerves, except for the impaired development of the dendritic trees of the Purkinje cells. In this study we quantitatively demonstrated decreased synaptic connections of parallel fibers on the dendritic spines of the Purkinje cells as early as 2 weeks after birth. On the other hand, synaptic boutons on the dendritic shafts and somata of the Purkinje cells and synaptic bouton-like structures which contained synaptic vesicles but without synaptic membrane specialization, were significantly increased in the molecular layer at 9 weeks of age. Glutamic acid decarboxylase immunohistochemistry suggested that some of these increased synaptic boutons and other bouton-like structures may have originated in GABA interneurons, such as stellate cells, basket cells and Golgi cells, and in the cerebellar nuclei. Because of the severity of the manifestations, it appears that synaptic alteration in interneurons also occurs in the other parts of the CNS.

Animals↗
PubMed1993

Developmental studies on the interparietal part of the human occipital squama.

The development of ossification centres in the membranous occipital squama is described, based on observations on human fetal skulls. The interparietal part develops basically from 3 pairs, 1 primary pair and 2 secondary pairs; an additional 4th pair is occasionally observed. The so-called separated interparietal bones (Inca bones) are formed by a failure of fusion between the primary and secondary centres, not between the supraoccipital and interparietal parts. The preinterparietal bones, which are developed from the additional 4th pair of interparietal ossification centres, are clearly differentiated from other anomalies in the lambda region by the shape of their territory and by their location. The issue still remains as to how to establish their identity in skulls from individuals of advanced age.

Adult↗
PubMed1992

Dendritic arbolization of large pyramidal neurons in the motor cortex of normal and reeler mutant mouse.

Reeler, an autosomal recessive mutation in mice, is characterized by abnormal positioning of the neurons in the cerebral cortex. We performed a descriptive analysis on the arborization of dendritic processes of large pyramidal neurons in the motor cortex (hindlimb area) of normal and reeler mice, as seen in the Golgi preparations. In the normal mouse, somata of large pyramidal neurons were located in the layer V, and their apical dendrites ascend vertically to the pial surfaces. Their basal dendrites proceed horizontally or inferiorly. In the reeler mouse, typical large pyramidal neurons with a normal (upright) apical dendrite and a variety of atypical large pyramidal neurons with a disoriented apical dendrite were radially scattered within the motor cortex. Typical large pyramidal neurons occupied the lower half of the motor cortex, whereas atypical large pyramidal neurons were predominantly observed in the upper half of the motor cortex. Atypical large pyramidal neurons were further divided into inverted, tumbled, V-shaped, bipolar and superficial polymorphic cells, as previously reported (Terashima et al., J. Comp. Neurol. 218:314-326, 1983). Superficial polymorphic cells localized in the layer of polymorphic cells and the layer of the large pyramidal cells were characterized by the extremely poor dendritic arborizations and the smooth surface of the dendrites, which suggests development of dendrites of these neurons was deranged by the reeler genetic locus.

Animals↗
PubMed1991

Immunoelectron microscopic study of a new D-amino acid oxidase-immunoreactive subcompartment in rat liver peroxisomes.

We report the presence of a new subcompartment in rat liver peroxisomal matrix in which only D-amino acid oxidase is localized and other matrix enzymes are absent. By electron microscopic observation, the rat liver peroxisome has generally been considered to consist of a single limiting membrane, an electron-dense crystalline core, and a homogeneous matrix. Immunohistochemical staining for D-amino acid oxidase by the protein A-gold technique revealed the presence of a small area in the matrix that was immunoreactive for the enzyme and was less electron-dense than the surrounding matrix. The localization of D-amino acid oxidase in this small area of the peroxisomal matrix was confirmed by immunoelectron microscopy on freeze-substituted tissues processed without chemical fixation. To analyze the characteristics of the electron-lucent area, immunoreactivity for various peroxisomal enzymes, including catalase, acyl-CoA oxidase, enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase bifunctional protein, 3-ketoacyl-CoA thiolase, L-alpha-hydroxy acid oxidase (isozyme B), and glycolate oxidase (isozyme A), was assayed. The electron-lucent area was negative for all of these. By double staining for D-amino acid oxidase and catalase, using colloidal gold particles of different sizes, these enzymes were shown to be located in separate areas in the matrix.

Animals↗
PubMed1991

Immunoelectron microscopic evidence for organ differences in the composition of peroxisome-specific membrane polypeptides among three rat organs: liver, kidney, and small intestine.

We examined the distribution of peroxisome-specific membrane polypeptides (PMPs) among peroxisomes of the liver, renal cortex, and jejunal mucosa, using antibodies for 70 KD, 26 KD and 22 KD PMPs. Immunoblot analysis showed signals for 70 KD polypeptide in all three kinds of tissue, but for the other two only in the liver and renal cortex, with neither being detected in jejunal mucosa. The total amounts of PMPs increased in all three organs with DEHP (di-(2-ethylhexyl)phthalate) administration. By immunoelectron microscopic analysis using protein A-gold, the three PMPs were localized along the peroxisomal membrane. Quantitation of the gold particles associated with the peroxisomal membrane showed an increase in the density of 70 KD and 26 KD PMPs but a decrease in 22 KD PMP with the administration of DEHP. The presence of tissue-specific localizations of PMPs suggest the 70 KD PMP is a common constituent of peroxisomes of these three tissues, whereas 26 KD and 22 KD PMPs are absent in microperoxisomes of jejunal mucosal epithelium.

ATP-Binding Cassette Transporters↗
PubMed1991

[Pterion and epipteric bones in Japanese adults and fetuses, with special reference to their formation and variations].

The formation and variations of the pterion and epipteric bones were examined in total of 614 Japanese skulls. The materials used consisted of 258 skulls of Japanese fetuses ranging from the fourth to the ninth month, 20 skulls of Japanese juveniles from the third month to 17 years of age, and 336 skulls of Japanese adults from 20 to 89 years of age. For the skulls examined the incidence of ossification in the fetal sphenoidal fontanelle was 3.6% on each side, whereas epipteric bones were observed in more than 10% of the juvenile and adult pteria. Great variation was seen in the form of the adult pterion. The most common form was a sphenoparietal contact in which the pteria were classified into usual (306 pteria), high (119), low (21), and narrow (32) types Another form of this type, a frontal process of the temporal bone without contact with frontal bone, was found in five pteria. The form of frontotemporal contact is classified into two types: One is with a frontal process of the temporal bone (17 pteria), and another is a K-shaped contact referred to as "stellate" (four). The two types were observable in adult skulls of all ages, although the fused pteria and fusing epipteric bones were most often seen in cases over 40 years of age. The results suggest that the pterion formation has two phases, the first occurring before the occlusion of sphenoidal fontanelle, and the second starting after 40 years of age.

Adolescent↗
PubMed1985

Synthesis, from cellobiose, of a trisaccharide closely related to the GlcNAc----GlcA----GlcN segment of the antithrombin-binding sequence of heparin.

O-(2-Deoxy-2-sulfamido-6-O-sulfo-alpha-D-glucopyranosyl)-(1----4)- O-(beta-D- glucopyranosyluronic acid)-(1----4)-1,6-anhydro-2-deoxy-2-sulfamido-6-O-sulfo-beta-D-gl ucopyranose pentasodium salt (14) was synthesized as a heparin-related oligosaccharide. The glycosyl acceptor (derived from cellobiose) and a glycosyl donor, 6-O-acetyl-2-azido-3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl bromide, were coupled in the presence of mercuric bromide and molecular sieves 4A to afford a 69% yield of fully protected trisaccharide, namely, O-(6-O-acetyl-2-azido-3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl)-(1 ----4)- O-(methyl 2,3-di-O-benzyl-beta-D-glucopyranosyluronate)-(1----4)-3-O-acetyl- 1,6-anhydro-2 - azido-2-deoxy-beta-D-glucopyranose (10), which was converted into the partially sulfated trisaccharide 14. Compound 10 also underwent acetolysis to afford the glycosyl acetate, for further elongation of the glycosyl chain.

Antithrombin III↗
PubMed1982

Whole-body retention and tissue distribution of 60Co in rats after oral administration of freshwater fish contaminated with 60Co.

The purpose of this report is to compare the whole-body retention and tissue distribution in rats of 60Co administered by gavage as inorganic 60CoCl2 or in a form incorporated into freshwater fish. Orizias latipes were placed in vessels containing 21. of tap water with radioactive cobalt. Periodically thereafter the fish were sacrificed, homogenized, and administered to rats via a stomach tube. Control groups of rats were given the radionuclide alone or together with a homogenate of nonradioactive fish. The whole-body retention and tissue distribution of the radionuclide were determined with an Armac counter. The results revealed that rats gavaged with 60Co incorporated into the fish retained much more 60Co than control rats. This trend was notable in rats given fish kept in radioactive solution for longer periods. Marked differences in tissue distribution of 60Co were also observed between rats given 60Co incorporated into fish and control rats.

Animals↗