Biomedical subjects
A Sugimoto
Publications and source records attributed to A Sugimoto.
[Dipyrrole bile pigments].
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Increased expression of heme oxygenase mRNA in rat brain following transient forebrain ischemia.
Heme oxygenase is a rate-limiting enzyme in heme catabolism, the end of which include iron, carbon monoxide and bilirubin. Expression of the inducible form of heme oxygenase (HO-1) was investigated in rat brain following 20 min of forebrain ischemia by Northern blot and in situ hybridization analyses. The level of HO-1 mRNA was undetectable in the cerebral cortex of sham control, but increased following ischemic insult, reached the maximum after 12 h of reperfusion, and then decreased. In sham control brain, HO-1 mRNA was detectable only in the scattered neuron-like cells within the dentate gyrus hilus. At 12 h of reperfusion, the remarkable increase in HO-1 mRNA levels was observed in both neuronal and glia-like cells distributed in the neocortex, hippocampus and thalamus.
Baculovirus p35 prevents developmentally programmed cell death and rescues a ced-9 mutant in the nematode Caenorhabditis elegans.
Programmed cell death, or apoptosis, occurs throughout the course of normal development in most animals and can also be elicited by a number of stimuli such as growth factor deprivation and viral infection. Certain morphological and biochemical characteristics of programmed cell death are similar among different tissues and species. During development of the nematode Caenorhabditis elegans, a single genetic pathway promotes the death of selected cells in a lineally fixed pattern. This pathway appears to be conserved among animal species. The baculovirus p35-encoding gene (p35) is an inhibitor of virus-induced apoptosis in insect cells. Here we demonstrate that expression of p35 in C. elegans prevents death of cells normally programmed to die. This suppression of developmentally programmed cell death results in appearance of extra surviving cells. Expression of p35 can rescue the embryonic lethality of a mutation in ced-9, an endogenous gene homologous to the mammalian apoptotic suppressor bcl-2, whose absence leads to ectopic cell deaths. These results support the hypothesis that viral infection can activate the same cell death pathway as is used during normal development and suggest that baculovirus p35 may act downstream or independently of ced-9 in this pathway.
NMDA receptor (NMDAR1) expression in the rat hippocampus after forebrain ischemia.
The influence of transient forebrain ischemia on the temporal alteration of NMDA receptor (NMDAR1) mRNAs in the hippocampal formation was analysed by in situ hybridization, RNA blot and in vitro receptor autoradiography ([3H]3-((+)2-carboxypiperazin-4-yl)-propyl-1- phosphonic acid). In the CA1 subfield of the hippocampus, decrease of NMDAR1 mRNA levels was not observed until death of the CA1 pyramidal cells. Reactive astrocytes, which appear after CA1 pyramidal cell death, expressed few NMDAR1. The CA3 and dentate gyrus also showed a reduction of NMDAR1 mRNA levels 7 days after ischemia. Temporal profiles of NMDAR1 mRNA levels correlated well with those of NMDA receptor-binding in the CA1 and CA3/dentate gyrus. These results indicate that NMDA receptors in the CA1 are predominantly located on the CA1 pyramidal cells and that these receptors are preserved during early recirculation period. Histologically intact neurons in the CA3 and dentate gyrus also had marked modulation in glutamatergic neurotransmission after ischemia.
Chemical structure of a new family of bile pigments from human urine.
Seven bilirubin metabolites negative to the diazo reaction were identified in the urine of healthy persons by enzyme-linked immunosorbent assay (ELISA) using the anti-bilirubin monoclonal antibody 24G7. Two of the seven metabolites were isolated and their chemical structures were determined using fast-atom bombardment-mass spectroscopy (FAB-MS) and 1H-NMR. The two metabolites are 1,14,15,17-tetrahydro-2,7,13-trimethyl-1,14- dioxo-3-vinyl-16H-tripyrrin-8,12-dipropionic acid and 1,14,15,17-tetrahydro-3,7,13-trimethyl-1,14-dioxo-2-vinyl-16H- tripyrrin-8,12-dipropionic acid. They are regioisomers of each other. The two bilirubin metabolites are novel tripyrrole biocompounds and belong to a third group of bile pigments following biliverdin and bilirubin. We gave these compounds the generic names biotripyrrin-a and biotripyrrin-b, respectively.
Exposure to sub-lethal ischemia failed to prevent subsequent ischemic death of dentate hilar neurons, as estimated by laminin immunohistochemistry.
The CA1 pyramidal cells and dentate hilar neurons are selectively vulnerable to forebrain ischemia. Although brief ischemia induces tolerance to subsequent ischemia in the CA1 pyramidal neurons, a protective effect of preceding brief ischemia on the dentate hilar neurons has not been established. We observed that vulnerable dentate hilar neurons were strongly laminin-immunopositive and used laminin immunohistochemistry to estimate the fate of dentate hilar neurons after ischemia. Pretreatment of brief sublethal ischemia, which effectively protects the CA1 neurons, failed to prevent the death of dentate hilar neurons. These results indicate that brief ischemia failed to induce tolerance to subsequent longer ischemia in the dentate hilar neurons.
Effect of calcium phosphate ceramic particle insertion on tooth eruption.
The effects of calcium phosphate ceramic implants on tooth eruption were investigated radiographically and histologically in 20 3-month-old dogs. Four kinds of ceramic particles were used: dense and porous hydroxyapatite particles, and dense and porous tricalcium phosphate particles. These particles were implanted in the sockets after deciduous tooth extraction. The four types of calcium phosphate ceramic particles produced similar radiographic and histologic findings. There was no delay of tooth eruption, no dysplasia, and no resorption of dental hard tissue.
Coordinated expression of messenger RNAs for nerve growth factor, brain-derived neurotrophic factor and neurotrophin-3 in the rat hippocampus following transient forebrain ischemia.
Changes in nerve growth factor, brain-derived neurotrophic factor and neurotrophin-3 messenger RNA expression in the rat hippocampus following 20 min of transient forebrain ischemia were evaluated using Northern blot analysis and in situ hybridization histochemistry. Twelve hours after the insult, the level of nerve growth factor messenger RNA increased markedly in the granular cell layer of the dentate gyrus and by day 2 returned to control levels. The level of brain-derived neurotrophic factor messenger RNA showed a persistent and moderate increase. The highest expression of brain-derived neurotrophic factor messenger RNA was seen in the dentate granule cells on day 2 after the insult, and then the expression returned to the control levels. At 2 days post-ischemia, contents of messenger RNAs for nerve growth factor and brain-derived neurotrophic factor were reduced in the CA1 region, which may represent delayed loss of vulnerable CA1 pyramidal neurons. In contrast to brain-derived neurotrophic factor and nerve growth factor messenger RNA expression, the level of neurotrophin-3 messenger RNA declined in the CA1, the CA2 and the dentate granular layer immediately after ischemic insult. In the CA1 region, the reduced expression persisted for at least seven days, but in the dentate gyrus, neurotrophin-3 messenger RNA expression returned to the control levels after two days of post-ischemic recovery. These results suggest that nerve growth factor, brain-derived neurotrophic factor and neurotrophin-3 genes are differentially regulated and that each of their gene products may play different roles in the central nervous system under pathophysiological conditions.
Synthesis and evaluation of iodinated benzamide derivatives as selective and reversible monoamine oxidase B inhibitors.
A new series of iodinated analogues of N-(2-aminoethyl)benzamide was synthesized and evaluated for inhibitory potency and specificity toward monoamine oxidase type-B (MAO-B). Among them, N-(2-aminoethyl)-2-chloro-4-iodobenzamide hydrochloride (2d) showed high inhibitory potency and selectivity against MAO-B. The type of MAO-B inhibition by 2d was non-competitive and the inhibition constant (Ki) was 0.80 microM. Strong and selective in vivo MAO-B inhibition by 2d was also confirmed. The brain MAO-B inhibition by 2d was reversible and the enzyme activity completely returned to the control value 24 h after administration. Compound 2d was, therefore, considered to be a candidate for advanced development as a radioiodinated ligand that may be useful for functional MAO-B studies in the living brain using single photon emission computer tomography.
Anti-bilirubin monoclonal antibody. III. Preparation and properties of monoclonal antibodies to unconjugated bilirubin-IX alpha.
Anti-bilirubin-IX alpha monoclonal antibodies exclusively specific for unconjugated bilirubin-IX alpha are prepared and characterized. Using modified MBS (metamaleimidobenzoyl-N-hydroxysuccinimide ester) method, bilirubin-IX alpha was covalently coupled to bovine serum albumin (BSA) retaining its intramolecular hydrogen bonds as well as three-dimensional structure. Somatic cell fusion was performed between murine spleen cells immunized with the bilirubin-IX alpha-BSA and murine myeloma P3-X63-Ag8-U1 cells. After screening assay, 58 clones were identified which were producing antibodies not to albumin nor MBS, but to haptenic bilirubin-IX alpha. In inhibition analysis, the antibodies in the culture supernatant reacted only with bilirubin-IX alpha to a varying degree, but did not react with conjugated bilirubin-IX alpha, including bilirubin-IX alpha monoglucuronide, bilirubin-IX alpha diglucuronide, and ditauronic bilirubin-IX alpha.
S. pombe pac1+, whose overexpression inhibits sexual development, encodes a ribonuclease III-like RNase.
The Schizosaccharomyces pombe pac1 gene is a multicopy suppressor of the pat1 temperature-sensitive mutation, which directs uncontrolled meiosis at the restrictive temperature. Overexpression of the pac1 gene had no apparent effect on vegetative growth but inhibited mating and sporulation in wild type S. pombe cells. In such cells, expression of certain genes required for mating or meiosis was inhibited. The pac1 gene is essential for vegetative cell growth. The deduced pac1 gene product has 363 amino acids. Its C-terminal 230 residues revealed 25% amino acid identity with ribonuclease III, an enzyme that digests double-stranded RNA and is involved in processing ribosomal RNA precursors and certain mRNAs in Escherichia coli. The pac1 gene product could degrade double-stranded RNA in vitro. These observations establish the presence of a RNase III homolog in eukaryotic cells. The pac1 gene product probably inhibits mating and meiosis by degrading a specific mRNA(s) required for sexual development. It is likely that mRNA processing is involved in the regulation of sexual development in fission yeast.
Histologic findings of apatite-titanium complex dental implants in the jaws of dogs.
This study concerns the histologic examination of apatite-titanium complex dental implants (two-piece, cylindrical type) in dogs. There was no plaque control. One to 3 months after implantation, the surface of the apatite root was directly bound to newly formed, woven bone. Seven-and-a-half months to 1 year after implantation, the apatite root was directly bound to the newly formed lamellar bone, which provided strong bone bonding (apatite-bone bonding). There appear to be two types of mechanisms for the resorption of apatite ceramics: first, cellular-type resorption by both multinuclear and mononuclear macrophages; and second, a noncellular, fluid mechanism (dissolution). The gingival sulcus around implants and downward growth of the epithelial cells could be observed in almost all of the implants. There was no cellular inflammation in the tissue around the implants, in the nasal cavity, or in the maxillary sinus. From this study we concluded that clinical application of this dental implant system would be practical.
Effects of nerve growth factor and cAMP on expression of acetylcholine receptor in PC12 cells.
The developmental change in acetylcholine-induced current (IACh) was investigated in PC12 cells cultured in the presence or absence of either nerve growth factor (NGF) or 8-Br-cAMP for 10 days. Currents were recorded in the whole-cell mode of the conventional patch-clamp technique. Morphological observations revealed that control cells do not undergo a change in morphology during culture. NGF-treated cells developed long neurites and had dense connections with other cells. 8-Br-cAMP-treated cells developed short neurites, and did not have dense connections. Control cells did not show a change in the mean density of IACh (VH = -80 mV) during the culture period. NGF-treated cells had a maximal increase in the current density of IACh at 5 days after the beginning of treatment, and did not show any further increase until 10 days. 8-Br-cAMP-treated cells had a decrease in current density during the first 6 days, but recovered to the control level after 7 days of treatment. It is concluded that maximal expression of ACh receptors occurs in the relatively early days of development, and that intracellular cAMP does not contribute greatly to their expression.
Protective effects of TJ-960 herbal mixture on hippocampal neuron damage induced by cobalt focus in the cerebral cortex of rats.
In the cobalt focus experimental epilepsy model, severe hippocampal neuron damage occurs with marked EEG changes. The effects of TJ-960, a herbal medicine formulation, were studied on neuron damage in the CA1 area of rat hippocampus. Continuous oral administration of TJ-960 from one month prior to the cobalt application showed almost complete protection against hippocampal neuron damage induced by cobalt application to the cerebral cortex. TJ-960 also completely inhibited the EEG changes as well as the brain edema induced by cobalt application.
Schizosaccharomyces pombe ste11+ encodes a transcription factor with an HMG motif that is a critical regulator of sexual development.
Schizosaccharomyces pombe ste11 encodes a member of the family of HMG-box proteins. Its transcript is induced in response to nitrogen starvation and a concomitant decrease of the intracellular cAMP level. Expression of ste11 is essential for induction of sexual development, and its ectopic expression stimulates uncontrolled mating and sporulation. Ste11 protein regulates positively transcription of the following genes required for sexual development: the mating type genes, matP and matM, and the mei2 gene, which is essential for commitment to meiosis. Ste11 protein synthesized in vitro binds specifically to a DNA fragment carrying a 10-base motif TTCTTTGTTY that is an essential cis-acting element for the induction of mei2 and is commonly seen in the upstream regions of the genes inducible by nitrogen starvation. These observations strongly suggest that Ste11 serves as a key transcription factor for sexual development.
Studies on hypotensive agents. Synthesis of 1-substituted 3-(2-chlorophenyl)-6-ethoxycarbonyl-5,7-dimethyl-2,4(1H,3H)-quinazoline diones.
3-(2-Chlorophenyl)-6-ethoxycarbonyl-5,7-dimethyl-2,4(1H,3H)-quinazoline dione was newly prepared. 1-Hydrogen atoms of the compound were variously substituted in order to test for their hypotensive activities on relaxing effects of the blood vessels. The compounds with 2-(1-pyrrolidinyl) ethyl, 2-(1-piperidinyl)ethyl, 3-(dimethylamino)propyl, and 3-(N-benzyl-N-methylamino)propyl moieties showed significant activity. The 2-(1-piperidinyl)ethyl compound possessed activity approximately 23 times more potent than papaverine, however, it was less potent than cinnarizine.
Effects of cycloheximide on delayed neuronal death in rat hippocampus.
The effect of cycloheximide, a protein synthesis inhibitor, on hippocampal selective neuronal death was morphologically studied in rats subjected to 10 min forebrain ischemia using a 4-vessel occlusion model. Neuronal damage in the hippocampal CA1 subfield 72 h after ischemic insult was dramatically decreased by the lasting inhibition of protein synthesis through consecutive administration of cycloheximide. Cycloheximide, which was administered once within the first 24 h of recirculation, showed protective action on ischemic cell necrosis and its most potent effect was observed when injected at 12 h of post-ischemia. After 36 h of recirculation, however, treatment with cycloheximide could no longer prevent cell death. The possibility is considered that hippocampal delayed neuronal death following transient ischemia is caused by abnormal protein(s).