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Biomedical subjects

H Abe

Publications and source records attributed to H Abe.

At least 127 records · Page 7Linked to original sources
PubMed2001

[Effect of extracellular Ca2+ on neuronal function].

Metabotropic glutamate receptors (mGluR) are well known to have a significance for the plastic change of synaptic neurotransmission. We observed that mGluR can be activated not only by glutamate but also by extracellular Ca(2+) of physiological concentration. Our observation suggests that extracellular Ca(2+) plays a critical role for the neuronal function, not only by serving as a source to elevate intracellular Ca(2+) concentration by entering through various channels, but also by activating metabotropic glutamate receptors as a ligand.

English Abstract↗
PubMed2000

Absence of endoproteolysis but no effects on amyloid beta production by alternative splicing forms of presenilin-1, which lack exon 8 and replace D257A.

It is well known that presenilin-1 (PS1) is involved in cleavage of amyloid precursor protein (APP) at the gamma-secretase site, and that the amino acids residues of D257 and D385 in PS1 are critical for this cleavage of APP and the endoproteolysis of itself. An alternatively spliced form of PS1 skipping exon 8 (PS1d8), which has D257A at the splice junction of exon 7/9, is expressed in human brain and in some cell lines. In this study, we examined production of Amyloid beta (A beta) and the endoproteolysis of the holoproteins in PS1d8-expressing neuroblastoma cells. Western blotting showed an absence of endoproteolysis in PS1d8. However, PS1d8 did not affect the production of A beta, which is different from the artificial point mutant PS1D257A. These results suggest that endoproteolysis of PS1 and gamma-secretase activity could be independent.

Alternative Splicing↗
PubMed2000

Simultaneous hypertensive intracerebral hematomas: two case reports.

We describe two patients (76- and 54-year-old females) with multiple hypertensive intracerebral hematomas occurring simultaneously. One patient had a right thalamic hematoma extending into the internal capsule and basal ganglia together with an other one in the left putamen. The other patient had two hematomas located ipsilaterally in the left putamen and thalamus. Their neurological examinations showed only unilateral deficits. Their magnetic resonance angiograms revealed no vascular malformations. Neuroradiological procedures are essential for the diagnosis of these multiple brain events.

Aged↗
PubMed2000

Postischemic temperature as a modulator of the stress response in brain: dissociation of heat shock protein 72 induction from ischemic tolerance after bilateral carotid artery occlusion in the gerbil.

Brief ischemia induces tolerance to subsequent more severe insults, and induction of the 70 kDa heat shock/stress protein, hsp72, has been suggested to play a role. This study tested the requirement for hsp72 expression in a gerbil tolerance model in which postischemic temperature was varied to modulate the level of hsp72 induction. Gerbils were subjected to 2 min bilateral common carotid artery occlusion and kept under halothane anesthesia for 90 min, during which rectal temperature was either maintained at 37 degrees C (normothermic, NT) or elevated to 39.5 degrees C (hyperthermic, HT) during 15-60 min recirculation. Hsp72 mRNA expression was determined by in situ hybridization with a (35)S-labeled oligonucleotide probe at 3, 24 and 48 h. Separate groups were subjected to a test challenge of 5 min ischemia 48 h after the priming insult, and CA1 neuron counts were obtained at 1 week. Significant protection was observed in both NT and HT groups. However, while 90% of hippocampi from NT animals showed detectable protection of CA1 neurons, less than half showed detectable hsp72 mRNA induction. These results indicate that, within the limits of experimental detection, hsp72 expression is not required for induction of ischemic tolerance.

Animals↗
PubMed2000

Complete nucleotide sequence of the prophage VT1-Sakai carrying the Shiga toxin 1 genes of the enterohemorrhagic Escherichia coli O157:H7 strain derived from the Sakai outbreak.

Shiga toxins 1 and 2 (Stx1 and Stx2) are encoded by prophages lysogenized in enterohemorrhagic Escherichia coli (EHEC) O157:H7 strains. Lytic growth of the phage particles carrying the stx1 genes (stx1A and stx1B) of the EHEC O157:H7 strain RIMD 0509952, which was derived from the Sakai outbreak in 1996 in Japan, was induced after treatment with mitomycin C, but the plaque formation of the phage was not detected. We have determined the complete nucleotide sequence of the prophage VT1-Sakai. The integration site of the prophage was identified within the yehV gene at 47.7 min on the chromosome. The stx1 genes were downstream of the Q gene in the prophage genome, suggesting that their expression was regulated by the Q protein, the regulator of the late gene expression of the phage, which is similar to that of the stx1 or stx2 genes carried by the lambdoid phages reported previously. The sequences of the N gene and its recognition sites, nutL and nutR, were not homologous to those of the phages carrying the stx genes thus far reported, but they were very similar to those of bacteriophage phi21. The sequences of the repressor proteins, CI and Cro, that regulate expression of the early genes had low similarities with those of the known repressors of other phages, and their operator sequences were different from any sequence reported. These data suggest that multiple genetic recombination among bacteriophages with different immunities took place to generate the prophage VT1-Sakai. Comparison between the sequences of VT1-Sakai and lambda suggests that the ancestor of VT1-Sakai was produced by illegitimate excision, like lambda gal and bio phages.

Amino Acid Sequence↗
PubMed2000

Quantitative Evaluation of Nystagmus by an Image-analysis System.

Purpose: We attempted to apply a newly developed image-analysis system for measurement and analysis of nystagmus.Method: Eye movements were recorded by digital video through a head-mounted charge coupled device (CCD) camera. The recorded movie was converted into black and white in order to detect the area of the pupil. Horizontal and vertical eye positions were determined by calculating the centroid of the pupil. Torsional angle was calculated using the iris striate pattern around the pupillary margin.Results: The parameters (amplitude, cycle, etc.) of nystagmus were calculated easily by the new image-analysis system from the recorded images. As examples, the foveation period was measured accurately in a case of jerky-type congenital nystagmus. Very regular cycles of intorsional attack period were revealed in a case of superior oblique myokymia. A case of cork-screw-like nystagmus showed a characteristic combination of large and small cycles unassociated with torsion.Conclusion: This image-analysis system was useful for quantitative analysis of nystagmus, and especially for measurement of torsion. Detailed waveforms and specific rhythms of nystagmus, which could not be recognized by observation, were demonstrated by this system.

Journal Article↗
PubMed2000

Arabidopsis basic leucine zipper transcription factors involved in an abscisic acid-dependent signal transduction pathway under drought and high-salinity conditions.

The induction of the dehydration-responsive Arabidopsis gene, rd29B, is mediated mainly by abscisic acid (ABA). Promoter analysis of rd29B indicated that two ABA-responsive elements (ABREs) are required for the dehydration-responsive expression of rd29B as cis-acting elements. Three cDNAs encoding basic leucine zipper (bZIP)-type ABRE-binding proteins were isolated by using the yeast one-hybrid system and were designated AREB1, AREB2, and AREB3 (ABA-responsive element binding protein). Transcription of the AREB1 and AREB2 genes is up-regulated by drought, NaCl, and ABA treatment in vegetative tissues. In a transient transactivation experiment using Arabidopsis leaf protoplasts, both the AREB1 and AREB2 proteins activated transcription of a reporter gene driven by ABRE. AREB1 and AREB2 required ABA for their activation, because their transactivation activities were repressed in aba2 and abi1 mutants and enhanced in an era1 mutant. Activation of AREBs by ABA was suppressed by protein kinase inhibitors. These results suggest that both AREB1 and AREB2 function as transcriptional activators in the ABA-inducible expression of rd29B, and further that ABA-dependent posttranscriptional activation of AREB1 and AREB2, probably by phosphorylation, is necessary for their maximum activation by ABA. Using cultured Arabidopsis cells, we demonstrated that a specific ABA-activated protein kinase of 42-kDa phosphorylated conserved N-terminal regions in the AREB proteins.

Abscisic Acid↗
PubMed2000

Detection of PTEN nonsense mutation and psiPTEN expression in central nervous system high-grade astrocytic tumors by a yeast-based stop codon assay.

We have developed a new yeast-based assay for the detection of PTEN nonsense mutation, and applied it to a total of 42 astrocytic tumors. The assay utilizes homologous recombination of PCR-amplified PTEN cDNA samples to a yeast vector which expresses an in-frame PTEN::ADE2 chimera protein. An allele of nonsense mutation in the sample PTEN mRNA gives a truncated chimera protein in a yeast cell, resulting in the formation of a red colony. The assay and subsequent sequence analysis demonstrated nonsense mutations as red colonies of more than 10% in one of 10 anaplastic astrocytomas and six of 18 glioblastomas, but none in six pilocytic astrocytomas or in eight astrocytomas. Sequence analysis of white colonies showed one missense mutation in a glioblastoma. Interestingly, four of seven nonsense mutations were frame-shifts due to exon skipping. In addition, pink colonies were found in one of six pilocytic astrocytomas, three of eight astrocytomas, two of 10 anaplastic astrocytomas, and 10 of 18 glioblastomas. Sequence analysis of the pink colonies revealed a sequence similar to those reported as psiPTEN/PTH2. By testing mRNA and genomic DNA, it was found to be a processed pseudogene which was transcribed. The psiPTEN expression was complementary to PTEN mutation, for 14 of 18 glioblastomas showed either PTEN mutation or psiPTEN expression and only one case showed both PTEN mutation and psiPTEN expression (P<0.046), suggesting a pathological role of psiPTEN expression as an alternative to PTEN mutation in glioblastomas.

Astrocytoma↗
PubMed2000

A rare case of multiple carcinoids and endocrine cell micronests in a patient with chronic duodenitis.

BACKGROUND: To the authors' knowledge, multiple carcinoid tumors of the duodenum have not been reported previously. However, multiple carcinoids in the stomach, ileum, and rectum, which were accompanied by the proliferation of endocrine cells, have been reported in the published literature. METHODS: A patient with multiple carcinoids including argyrophilic cell hyperplasia of the duodenum and hypergastrinemia underwent surgery. The resected stomach and duodenum were analyzed histopathologically. RESULTS: There were 11 carcinoid lesions, each of which was accompanied by peripheral endocrine cell micronests (ECMs). Increasing gastrin positive cells in the antral region and chronic duodenitis in the duodenal bulb also were observed. The peripheral ECMs usually were adjacent to proliferating argyrophilic cells in the Brunner gland ducts or the crypts of Lieberkühn, which showed focal pyloric gland metaplasia. CONCLUSIONS: In the case presented in the current study, the development of the multiple carcinoid lesions may be strongly related to the presence of multifocal pyloric gland metaplasia, as well as to the trophic action of gastrin, which is present at high levels in the setting of chronic duodenitis.

Carcinoid Tumor↗
PubMed2000

Multifocal Electroretinogram in Central Serous Chorioretinopathy.

Purpose: An assessment of retinal function topographically in the affected eyes with central serous chorioretinopathy (CSC).Participants and Method: We recorded multifocal electroretimogram (mERG) in 5 patients with unilateral CSC, and analyzed the topographical properties in the central visual field (rings #1 + 2).Results: mERG amplitudes in the CSC eyes were significantly reduced compared with the fellow eyes, for P 1-N 1 (58.5 +/- 23.5%, p < 0.05) and for P 1-N 2 (47.5 +/- 15.0%, p < 0.05). mERG latencies in the CSC eyes were significantly increased compared with those in the fellow eyes, for N 1 (by 9.0 +/- 8.1%, p < 0.05) and for P 1 (by 8.4 +/- 7.0%, p < 0.05). mERG in the CSC eyes gradually recovered in the follow-up period. However, the responses did not recover to normal value during follow-up, even when the subretinal fluid disappeared ophthalmoscopically.Conclusions: These results show that a topographical analysis of the mERG is useful for clinical observation of CSC.

Journal Article↗
PubMed2000

Neurological accidents caused by repetitive breath-hold dives: two case reports.

We report two Japanese male professional breath-hold divers (33 and 39 years of age) who experienced neurological disorders during repetitive dives to over 20 m of seawater. One patient had right homonymous hemianopsia, and the other presented with right hemiparesis with facial involvement and sensory deficit. In addition, they each had a history of neurological problems following such dives. Magnetic resonance images of their brains disclosed multiple T2-weighted hyperintensities corresponding to their neurological symptoms. Their brain lesions suggest a multiple cerebral infarction caused by occlusion of the cerebral arteries. We conclude that the repetitive deep breath-hold dives induced the brain involvement.

Adult↗
PubMed2000

Protective effect of microglial conditioning medium on neuronal damage induced by glutamate.

To examine the effect of microglial conditioning medium (MCM) on damaged neurons, cultured neurons exposed to glutamate were incubated with MCM. More neurons survived in these groups, particularly in the case of glutamate stimulation of microglia. Therefore cultured neurons exposed to glutamate were incubated with MCM at predetermined intervals after glutamate stimulation. Neuronal cultures using MCM at 1, 2 and 6 h after glutamate stimulation had more surviving cells than those using unstimulated MCM. Neuronal cultures using MCM at 12 and 24 h had as much surviving cells as those using unstimulated MCM. These results indicate that the neuroprotective effect of microglia appears only in the early phase after treatment of glutamate and disappears in the late phase.

Animals↗
PubMed2000

Synthesis of the C-glycosidic analogue of adenophostin A and its uracil congener as potential IP(3) receptor ligands. Stereoselective construction of the C-glycosidic structure by a temporary silicon-tethered radical coupling reaction.

Synthesis of the C-glycosidic analogue 9 of adenophostin A, a very potent IP(3) receptor agonist, and its uracil congener 10 was achieved via a temporary silicon-tethered radical coupling reaction as the key step. Phenyl 3,4, 6-tri-O-(p-methoxybenzyl)-1-seleno-beta-D-glucopyranoside (27) and 3-deoxy-3-methylene-1, 2-O-isopropylidene-alpha-D-erythro-pentofuranose (30) were connected by a dimethylsilyl tether to give the radical coupling reaction substrate 24, which was successively treated with Bu(3)SnH/AIBN in benzene and TBAF in THF to give the coupling product 25 with the desired (3alpha,1'alpha)-configuration as the major product. From 25, the targets 9 and 10 were synthesized via introduction of adenine or uracil base by Vorbrüggen's method and phosphorylation of the hydroxyls by the phosphoramidite method.

Adenosine↗
PubMed2000

Chronic inhibitory effect of insulin on plasma lipid concentrations in rats with transplanted pancreas.

BACKGROUND: Hyperinsulinemia, which is usually related to insulin resistance, is considered to be an important risk factor for coronary artery disease. Our study examines the influence of portal delivery of endogenous insulin after pancreas transplantation on plasma lipid metabolism, as compared with systemic delivery of insulin. METHOD: Pancreas was transplanted heterotopically in normal rats by anastomosis of the donor portal vein to the recipient portal vein (PPTx) or inferior vena cava (CPTx) as an in vivo model of endogenous hyperinsulinemia. RESULTS: The mean value of plasma insulin concentration of CPTx and PPTx rats was 149 and 165% that of control rats, whereas the plasma glucose concentration of CPTx and PPTx rats did not differ significantly from that of control rats. Plasma triglyceride (TG) concentrations were significantly lower in both PPTx and CPTx rats than control rats. During the intravenous glucose tolerance test, the area under the insulin concentration curves of CPTx and PPTx rats was 204 and 215% that of control rats, and they were correlated negatively with plasma TG concentrations. Plasma cholesterol and TG concentrations were significantly lower in PPTx rats than in control and CPTx rats. CONCLUSIONS: Chronic hyperinsulinemia has a dose-dependent inhibitory effect on the regulation of plasma TG concentrations in rats with a transplanted pancreas. Significant lower lipid levels in PPTx rats than in CPTx rats suggest that portal delivery of insulin from the transplanted pancreas is relatively preventive for the atherosclerotic process as compared with systemic delivery of insulin.

Anastomosis, Surgical↗
PubMed2000

Developmental changes in expression of the three ryanodine receptor mRNAs in the mouse brain.

Ryanodine receptors (RyR) are Ca(2+)-induced Ca(2+) release channels located on the endoplasmic reticulum, and consist of three isoforms, termed RyR1-3. We examined their expression in developing mouse brains by in situ hybridization. During the embryonic stage, RyR1 mRNA levels were highest in the rostral cortical plate, whereas RyR3 mRNA was most prominent in the caudal cortical plate and hippocampus. Initially, low levels of RyR2 mRNA were distributed in the diencephalon and brainstem. However, from postnatal day 7 onward, RyR2 mRNA became the major isoform in many brain regions, while RyR1 mRNA became prominent in the dentate gyrus and Purkinje cell layer. Postnatal down-regulation in the caudal cerebral cortex restricted RyR3 mRNA expression to the hippocampus, particularly the CA1 region. Therefore, RyR expression undergoes dynamic changes during the early postnatal period, when neurons are undergoing structural and functional differentiation.

Animals↗
PubMed2000

ACTH(4-12) is the minimal message sequence required to induce the differentiation of mouse epidermal melanocytes in serum-free primary culture.

It is well known that alpha-melanocyte stimulating hormone (MSH) induces the differentiation of mouse epidermal melanocytes in vivo and in vitro. Although adrenocorticotropic hormone (ACTH) possesses the same amino acid sequence as MSH does, it is not clear whether the peptide and its fragments induce the differentiation of mouse epidermal melanocytes. In this study, the differentiation-inducing potencies of human ACTH and its fragments were investigated by adding them into a culture medium (0.001-1,000 nM) from the initiation of primary culture of epidermal cell suspensions. Their potencies were compared with the potency of alpha-MSH. After 2-4 days of primary cultures with ACTH(1-13), ACTH(1-17), ACTH(1-24), ACTH(1-39), ACTH(4-12), ACTH(4-13), and alpha-MSH, pigment granules appeared in the cytoplasms and dendrites of melanoblasts that were in contact with the adjacent keratinocyte colonies. By 14 days, cultures contained mostly pigmented melanocytes. The order of potencies of ACTH fragments and alpha-MSH shown by the ED(50) value was as follows: alpha-MSH = ACTH(1-13) = ACTH(1-17) = ACTH(4-12) = ACTH(4-13) > ACTH(1-24) > ACTH(1-39). The length of their peptide chains was inversely proportional to the potency. On the contrary, ACTH(1-4), ACTH(11-24), and ACTH(18-39) failed to induce the differentiation of melanocytes. In contrast, ACTH(1-10), ACTH(4-10), ACTH(4-11), and ACTH(5-12) possessed a weak potency at high doses only (100 and 1,000 nM). These results suggest that ACTH(4-12) is the minimal message sequence required to induce the differentiation of mouse epidermal melanocytes in culture completely. The amino acids of Met(4) and Pro(12) are suggested to be important for its potency.

Adrenocorticotropic Hormone↗
PubMed2000

Stimulation by eicosapentaenoic acids of leptin mRNA expression and its secretion in mouse 3T3-L1 adipocytes in vitro.

Recent evidence indicates that both leptin and eicosapentaenoic acids (EPA) improve insulin sensitivity. In the present study, we examined the effect of EPA on endogenous leptin expression in 3T3-L1 adipocytes to clarify whether the EPA's effect is exerted through leptin expression. EPA caused a time- and dose-dependent increase of leptin mRNA levels in 3T3-L1 adipocytes. Leptin mRNA expression was significantly increased up to 309.4 +/- 17.0% of the control by 24 h (P < 0.01; n = 6). Leptin secretion was also significantly increased up to 193.3 +/- 12.1% of the control by 24 h (P < 0.01; n = 6). EPA is a ligand for peroxisome proliferator-activated receptors (PPARs) with the highest affinity to PPARalpha. We examined the effect on leptin expression of clofibrate, a ligand for PPARalpha, bezafibrate, for PPARbeta, or troglitazone, for PPARgamma, to clarify whether these ligands for PPARs could mimic EPA-induced stimulation of leptin expression. Neither clofibrate nor bezafibrate affected leptin mRNA expression, whereas troglitazone significantly suppressed leptin mRNA expression. On the other hand, inhibition by 6-diazo-5-oxo-l-norleucine of the rate-limiting enzyme in hexosamine biosynthesis blunted EPA-induced stimulation of leptin mRNA expression and its secretion. These data suggest that EPA up-regulates leptin gene expression and its secretion probably through a hexosamine biosynthetic pathway.

3T3 Cells↗