Search PubMed⌕ Search

Biomedical subjects

H Takagi

Publications and source records attributed to H Takagi.

At least 379 records · Page 21Linked to original sources
PubMed1997

Localization of manganese superoxide dismutase in the cerebral cortex and hippocampus of Alzheimer-type senile dementia.

Manganese-superoxide dismutase (Mn-SOD) was localized in the cerebral cortex and hippocampus of patients with Alzheimer-type senile dementia (ATD) by immunocytochemistry and the relationship of Mn-SOD with two major pathological features of ATD, i.e., senile plaques and neurofibrillar tangles (NFTs), was examined. Many astrocytes in senile plaques exhibited strong immunoreactivity for both Mn-SOD and glial fibrillar acidic protein (GFAP) on serial section analysis. This suggests that Mn-SOD scavenger system is associated with the formation of senile plaques. On the other hand, Mn-SOD immunoreactivity was not significant in NFT-loaded neurons.

Aged↗
PubMed1997

Specific retinal diacylglycerol and protein kinase C beta isoform modulation mimics abnormal retinal hemodynamics in diabetic rats.

PURPOSE: Elevation of diacylglycerol (DAG) and protein kinase C (PKC) levels in diabetic vascular tissue is associated with abnormalities of retinal and renal hemodynamics. The object of this study was to determine whether direct elevation of retinal DAG levels, in the absence of diabetes or hyperglycemia, can mimic the hemodynamic abnormalities normally observed in diabetic rats. Retinal DAG levels were elevated using an inhibitor of DAG kinase that converts DAG to phosphatidic acid. The effectiveness of a specific PKC-beta isoform inhibitor introduced directly into the retinas of diabetic rats in reversing diabetes-related abnormal retinal hemodynamics was also investigated. METHODS: For retinal blood flow studies, diacylglycerol kinase (DGK) inhibitor R59949, at various concentrations, was injected into the vitreous of nondiabetic Sprague-Dawley rats (n = 33), and a PKC-beta isoform-selective inhibitor LY333531 was injected into the vitreous of rats with streptozotocin (STZ)-induced diabetes of 2 weeks' duration (n = 21). Retinal hemodynamic changes were quantitated using video-based fluorescein angiography. Total DAG levels were assayed from five nondiabetic rat retinas after DGK inhibition and retinal PKC activities were assayed from six diabetic rat retinas after PKC-beta inhibition. RESULTS: DGK inhibitor R59949 injected into the vitreous dose dependently increased the mean circulation time (MCT) and decreased retinal blood flow (EC50 = 10(-8) M). After 30 minutes, 10(-5) M R59949 induced a 1.7-fold increase in total retinal DAG levels, compared with the levels in vehicle-injected eyes, an increase in MCT from 0.87 +/- 0.05 seconds to 1.44 +/- 0.12 seconds (P < 0.01) and a decrease in retinal blood flow from 105.3 +/- 6.5 pixel2/second to 64.1 +/- 5 pixel2/second (P < 0.01). The effect of R59949 was sustained for 60 minutes after injection. These retinal hemodynamic parameters after DGK inhibition were comparable to those measured at baseline in rats with STZ-induced diabetes of 2 weeks' duration (MCT = 1.38 +/- 0.20 seconds; retinal blood flow = 68 +/- 11.2 pixel2/second). Intravitreal injection of the PKC-beta inhibitor (LY333531) at 10(-5) M in diabetic rats decreased by a factor of 1.6 the diabetes-related increased PKC activation, decreased the prolonged MCT (0.98 +/- 0.13 seconds; P < 0.01) and increased retinal blood flow (93.4 +/- 14.2 pixel2/second; P < 0.01). The measured retinal circulatory parameters after PKC inhibition in the retina were comparable to those measured at baseline in the nondiabetic rats. CONCLUSIONS: These results provide direct evidence that DAG elevation and subsequent PKC-beta isoform activation are the primary biochemical sequelae responsible for the development of the abnormal retinal hemodynamics observed in diabetic rats.

Animals↗
PubMed1997

Effects of KB-2796 on plasma extravasation following antidromic trigeminal stimulation in the rat.

We investigated the effects of KB-2796 (1-[bis(4-fluorophenyl)methyl]-4-(2,3,4-trimethoxybenzyl)piperazine dihydrochloride), a novel calcium channel blocker, on neurogenic inflammation caused by electrical stimulation in the trigeminal ganglion and on cutaneous reactions induced by inflammatory mediators in rats, by measuring plasma extravasation. Neurogenic inflammation was inhibited by pretreatment with capsaicin (25 mg/kg, s.c.) but not indomethacin (10 mg/kg, i.p.), while phosphoramidon (2.5 mg/kg, i.v.) augmented it. KB-2796 (0.1-1 mg/kg, i.v.) significantly inhibited neurogenic inflammation in a dose dependent manner, without affecting histamine-, bradykinin- or substance P-induced cutaneous reactions. Dimetotiazine (0.3 and 1 mg/kg, i.v.), flunarizine (1 mg/kg, i.v.), mepyramine (1 mg/kg, i.v.) and sumatriptan (1 mg/kg, i.v.) significantly inhibited neurogenic inflammation. However, these compounds also showed complete or partial inhibition of histamine-, bradykinin- or substance P-induced reactions. Nifedipine (0.1 mg/kg, i.v.) did not show marked effects on neurogenic inflammation and cutaneous reactions. The present experiments indicate that neurogenic inflammation is presumably mediated not only by neuropeptides released from trigeminal nerve endings but also by secondarily released histamine, and that KB-2796 like sumatriptan may inhibit neurogenic inflammation caused by trigeminal nerve stimulation probably through inhibition of neuropeptide release but its inhibition may be distinct from the calcium blocking action of the 1,4-dihydropyridine type.

Animals↗
PubMed1997

[Relationships between resting behavior and health locus of control among elementary schoolgirls].

PURPOSE: To clarify the effects of Internal Health Locus of Control (IHLC) on the practice of resting behavior. Resting has recently gained attention because of overwork and stressful social situations. We investigated daily preventive health behaviors and Health Locus of Control (HLC) in children and their mothers over three years from 1991. This paper reports on the relationships between resting and IHLC among elementary schoolgirls. METHODS: The subjects of this study in 1991 were public elementary schoolgirls in their 3rd year (8-9 years old) and their mothers. Three years, later in 1994, we investigated the same children and their mothers, with 104 girls answering questionnaires in both studies. The resting behavior data was obtained from the question "Do you rest or take a nap when you are very tired?". We used Parcel & Meyer's Children's HLC Scales for children and Horige's Japanese version of Health Locus of Control (JHLC) Scales for mothers. Only the data concerning IHLC was extrapolated for this study. RESULTS: 1. The data for resting behavior for 1991 in the 3rd grade did not coincide with that for 1994 in the 6th grade. On the whole rest was taken more frequently in the 3rd grade than in the 6th grade. 2. Perceived health state had a significant association with resting behavior. 3. Girls who perceived rest was relating directly to their personal health, took a rest more often than those who did not perceive a personal application for rest. 4. IHLC data distribution shows a marked difference between grades. Scores were significantly higher in the 6th grade than in the 3rd grade. This rising tendency of internality seems to be a developmental change. 5. IHLC scores of 1991 3rd graders classified their 3rd grade behavior patterns. The 3rd grade (1991) "usually taking a rest" group scored significantly higher than the other groups. 1991 IHLC scores classified their 1994 6th grade behavior patterns. The 6th grade (1994) "usually taking a rest" group also scored significantly higher than the other groups. 6. The data for resting behavior of the girls did not coincide with that of their mothers. There were no correlations between the girls's IHLC scores and their mothers's IHLC scores. CONCLUSION: This study revealed some significant relationships between resting behaviors and IHLC scores among the schoolgirls. It seems that girls who had high IHLC tendency in the 3rd grade were growing up with this tendency. Perhaps in the interest of self-care, they elected to rest to keep healthy when they were tired.

Adult↗
PubMed1997

[A 13-week subacute oral toxicity study of pectin digests in rats].

A 13-week subacute oral toxicity study of pectin digests was performed in both sexes of F344 rats. Water containing 0, 0.15, 0.5, 1.5 or 5% pectin digests was fed to 10 males and 10 females per group to detect its toxicity. No animals died during the administration period. Body weight gain was suppressed in male of the 5% group compared with the 0% group. Serum biochemistry analysis revealed a significant increase in BUN in male group treated with 5% and increases in CRN in male group treated with 1.5% or more. The weight of liver was significantly increased in female groups treated with 1.5% or more. Histopathologically, no treatment-related damage was observed in any dosed groups. Based on these results, the NOEL of pectin digests for both sexes in F344 rats was considered to be 0.5% in drinking water (male 545, female 657 mg/kg/day).

Administration, Oral↗
PubMed1996

Characterization of vascular endothelial growth factor's effect on the activation of protein kinase C, its isoforms, and endothelial cell growth.

Vascular endothelial growth factor (VEGF) is a potent endothelial cell mitogen which mediates its effects by binding to tyrosine kinase receptors. We have characterized the VEGF-activated intracellular signal transduction pathway in bovine aortic endothelial cells and correlated this to its mitogenic effects. VEGF induced concentration- and time-dependent increases in protein kinase C (PKC) activation with a maximum of 2.2-fold above the basal level at 5 x 10(-10) M within 10 min as measured both by in situ and translocation assays. Immunoblotting analysis of PKC isoforms in cytosolic and membrane fractions indicated that after VEGF stimulation the content of Ca(2+)-sensitive PKC isoforms (alpha and betaII) was increased in the membrane fractions, whereas no changes were observed for PKC isoforms delta and epsilon. The stimulation of PKC activity by VEGF was preceded by the activation of phospholipase Cgamma (PLCgamma). This was demonstrated by parallel increases in PLCgamma tyrosine phosphorylation, [3H]inositol phosphate production, and [3H]arachidonic acid-labeled diacylglycerol formation in bovine aortic endothelial cells. In addition, VEGF increased phosphatidylinositol 3-kinase activity 2.1-fold which was inhibited by wortmannin, a phosphatidylinositol 3-kinase inhibitor, without decreasing the VEGF-induced increase in PKC activity or endothelial cell growth. Interestingly, genistein, a tyrosine kinase inhibitor, and GFX or H-7, PKC inhibitors, abolished both VEGF-induced PKC activation and endothelial cell proliferation. VEGF's mitogenic effect was inhibited by a PKC isoform beta-selective inhibitor, LY333531, in a concentration-dependent manner. In contrast, antisense PKC-alpha oligonucleotides enhanced VEGF-stimulated cell growth with a simultaneous decrease of 70% in PKC-alpha protein content. Thus, VEGF appears to mediate its mitogenic effects partly through the activation of the PLCgamma and PKC pathway, involving predominately PKC-beta isoform activation in endothelial cells.

Animals↗
PubMed1996

Restriction of substrate specificity of subtilisin E by introduction of a side chain into a conserved glycine residue.

Substitution of the conserved Gly127 for residues having a side chain markedly changed the substrate specificity of subtilisin E from Bacillus subtilis. The crystallographic findings suggested that Gly127 is responsible for accepting even the large P1 substrates, and the marked change of specificity was attributed to the introduction of a side chain in this position. To test this hypothesis, Gly127 was replaced with 3 non-charged amino acids, Ala, Ser and Val. When assayed with synthetic peptide substrates, all mutants purified from the periplasmic space in Escherichia coli showed a marked preference for small P1 substrate up to 150-fold relative to the wild-type. The kinetic data and molecular modeling analysis suggest that large hydrophobic P1 residues were unable to access the binding pocket due to steric hindrance.

Amino Acid Sequence↗
PubMed1996

Transforming growth factor-beta is a survival factor for neonate cortical neurons: coincident expression of type I receptors in developing cerebral cortices.

Transforming growth factor-beta (TGF-beta) is a multifunctional polypeptide which plays a crucial role in the regulation of cell proliferation, differentiation, and organogenesis. In the present study, we investigated the expression of signaling receptors for TGF-beta in developing mice by in situ hybridization, revealing a significant difference in the expression of TGF-beta type I and type II receptors. Unexpectedly, the TGF-beta type I receptors were exclusively expressed without any detectable expression of the TGF-beta type II receptors in developing cerebral cortices. In primary cortical neurons, a neutralizing antibody for TGF-beta significantly reduced the expression of bcl-2 and subsequently induced neuronal cell death, indicating that TGF-beta functions as a survival factor for cortical neurons in vitro. Consistent with the result of in situ hybridization, the TGF-beta, type I but not type II receptors were detected in primary cortical neurons by affinity crosslink and RT-PCR analyses. The concomitant expression of TGF-beta2 and the TGF-beta type I receptors in developing cerebral cortices suggests that the TGF-beta signaling system plays a pivotal role in neuronal differentiation and that unidentified components may be involved in TGF-beta signaling in the development of the central nervous system.

Animals↗
PubMed1996

Role of Fc fragments in inhibition of xenogenic hyperacute rejection by intravenous immunoglobulin.

It has been shown that a high dose administration of human intravenous immunoglobulin G (IVIG) prolonged the survival time of xenografted guinea pig heart in the rat. In this study, we compared the effectiveness of intact IVIG (I-IVIG), Fc fragments of IVIG (Fc-IVIG), and F(ab') fragments of IVIG (Fab-IVIG) in preventing xenogenic hyperacute rejection in the guinea pig-to-rat heart transplantation model. Relatively high dose administration of IVIG (0.6 g/kg body weight) induced xenograft survival times of 32.0 +/- 13.0 min and 33.2 +/- 16.8 min with I-IVIG and Fab-IVIG, respectively, which were significantly longer than times for animals treated with Fc-IVIG or for untreated control animals (survival times of 12.6 +/- 7.4 min and 10.4 +/- 7.6 min, respectively). The in vitro inhibitory effect of guinea pig red blood cell hemolysis by fresh rat serum correlated with the results of in vivo study. On the other hand, the in vitro inhibitory effect of IVIG on pig red blood cell hemolysis by fresh human serum showed that Fc-IVIG, which had little effect in the guinea pit-to-rat combination, had a higher inhibitory effect than Fab-IVIG, or I-IVIG. Fc-IVIG and I-IVIG achieved a complete inhibition of in vitro hemolysis in the pig-to-human combination. It is suspected that an interference with the complement classical pathway by the Fc portion of IVIG could be an attractive tool for inhibition of hyperacute rejection in the pig-to-human combination.

Acute Disease↗
PubMed1996

Kyotorphin (L-tyrosyl-L-arginine) as a possible substrate for inducible nitric oxide synthase in rat glial cells.

L-Arginine (L-Arg) is an endogenous substrate for nitric oxide synthase (NOS). In the present study, we examined whether L-tyrosyl-L-Arg (kyotorphin), an endogenous analgesic neuropeptide, might be a substrate for inducible NOS (iNOS) in the brain. Both kyotorphin and L-Arg caused an accumulation of nitrites in lipopolysaccharide (LPS)-treated glial cells cultured from infant rat brains. However, such accumulation of nitrites was not induced by NG-nitro-L-Arg (a NOS inhibitor), L-tyrosyl-D-Arg (D-kyotorphin) or D-Arg. L-Leucyl-L-Arg (an antagonist for kyotorphin receptors) or bestatin (an inhibitor for kyotorphin-hydrolyzing peptidase) did not inhibit the kyotorphin-induced accumulation of nitrites in LPS-treated cells. On the contrary, L-Leucyl-L-Arg caused an accumulation of nitrites in a concentration-dependent manner. The results indicate that nitric oxide (NO) is produced in LPS-treated glial cells directly from kyotorphin through the catalytic action of iNOS.

Analgesics↗
PubMed1996

Two components of exocytosis and endocytosis in phaeochromocytoma cells studied using caged Ca2+ compounds.

1. Changes in membrane capacitance evoked by the rapid photolysis of a caged Ca2+ compound, DM-nitrophen or nitrophenyl-EGTA, were investigated in undifferentiated PC12 cells. They were interpreted as representing exocytosis and endocytosis. 2. The Ca2+ jumps evoked two components of exocytosis. Slow exocytosis was selectively evoked with small increases in intracellular Ca2+ concentration between 5 and 10 microM, while fast exocytosis preceded the slow one at [Ca2+]i greater than 10 microM. 3. The release rates of the two components of exocytosis depended steeply on [Ca2+]i. A half-maximal release rate was achieved at 8 and 24 microM for the slow and fast exocytoses, respectively. 4. Prior Ca2+ rises did not augment the fast exocytosis. 5. The fast exocytosis was often followed by a rapid decrease in membrane capacitance, representing endocytosis, after a delay of 0.5-2 s. The speed and delay in the fast endocytosis were Ca2+ dependent. Amounts of the fast endocytosis tended to balance with those of the fast exocytosis evoked by the same Ca2+ jumps. 6. The slow exocytosis was followed by a sluggish endocytosis that was associated with large capacitance steps indicative of secretory processes involving large dense-core vesicles. The onset of the slow endocytosis exhibited a complex Ca2+ dependence. The amounts of the slow endocytosis appeared to parallel those of the slow exocytosis. Prior induction of the slow exocytosis gave rise to selective excess retrieval of membrane during the slow endocytosis. 7. These data indicate the existence of two distinct populations of secretory vesicles in PC12 cells. They seem to couple selectively with specific endocytotic mechanisms. Our data suggest that the two vesicles belong to two distinct secretory pathways.

Animals↗
PubMed1996

The efficient production of human epidermal growth factor by Bacillus brevis.

A system has been developed for the efficient production of heterologous proteins using Bacillus brevis as a host that secretes large amounts of cell wall protein into the medium. The promoter region and signal peptide-encoding region of the cell wall protein gene were used to construct an expression-secretion vector. Bacterial proteins such as amylases can be produced in large amounts by this system (1 g/l or more), but mammalian proteins such as human alpha-amylase are produced at a low level (one or two orders of magnitude less than for bacterial proteins). The highly efficient secretion of human epidermal growth factor (h-EGF, more than 1 g/l) was obtained with B. brevis HPD31 as the host and plasmid pHY481, derived from B. brevis 481, as the vector. Recombinant hEGF was purified easily from the culture supernatant by two steps. Purified hEGF had the identical NH2-terminal amino acid sequence and COOH-terminal amino acid sequence with those of the authentic hEGF, and it was fully active in biological assays. This recombinant hEGF has been shown to be successful for biological wool harvesting (CSIRO, Australia). These results, in combination with previous results, indicate that foreign proteins of diverse origins can be produced efficiently as functional proteins in B. brevis.

Amino Acid Sequence↗
PubMed1996

Identification and characterization of presenilin I-467, I-463 and I-374.

We cloned a novel isoform of presenilin I (presenilin I-374) besides previously published presenilin I-467 and I-463 in human lymphocytes. Presenilin I-463 was identical to presenilin I-467 except a 12 bp nucleotides deletion in its amino terminal region. Another isoform, presenilin I-374 was produced by an alternative splicing with an additional exon consisting of 92 bp nucleotides (exon 11), which resulted in the frame shift with a stop codon to generate a truncated presenilin consisting of 374 amino acids. The transcripts for presenilin I-467/463 was ubiquitously detected while that for presenilin I-374 was selectively detected in liver, spleen, kidney. Abnormal behavior of presenilin I on gel electrophoresis was found with affinity-purified antibodies against presenilin I.

Alzheimer Disease↗
PubMed1996

Inhibitory effect of double transfection to xenoendothelial cells using both decay accelerating factor and homologous restriction factor 20 genes on complement dependent cytolysis.

Hyperacute rejection in discordant xenotransplantation occurs due to the complement activation via classical and/or alternative pathway. Regulator of complement activation (RCA) molecules inhibit species-specific complement dependent cytolysis. To confirm the effect of gene engineering using double RCA molecules on xenogeneic cells, the inhibitory effect on complement dependent cytolysis was compared between bovine aortic endothelial cells (BAEC) doubly transfected with both decay accelerating factor (DAF) and homologous restriction factor (HRF) 20 cDNA and BAEC singly transfected with DAF alone using retroviral vector. The positive percent expression of DAF and HRF20 antigen on double transfectant (BAEC/D+H) was 97.0% and 95.0%, respectively, whereas that of DAF antigen on single transfectant (BAEC/D) was 97.0%. After incubated with 25% human serum and anti-BAEC antibody, the viability of double transfectant (BAEC/ D+H) was significantly preserved, compared with that of single transfectant (BAEC/D). These findings demonstrated that xenoendothelial cells doubly transfected with both DAF and HRF20 cDNA could be protected from complement dependent cytolysis more effectively than those singly transfected with DAF alone in the presence of antixenoendothelial antibody.

Animals↗