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T Nara

Publications and source records attributed to T Nara.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Epileptogenesis of acute encephalitis and acute encephalopathy: epilepsy with its onset in the acute phase and without a latent period].

Epileptogenesis was evaluated in 60 patients with acute encephalitis and in 10 patients with acute encephalopathy. Forty-seven patients have been seizure-free during for more than three years' follow-up (Group III). On the other hand, 23 patients developed epilepsy. Among them, 18 patients developed epilepsy after a latent period of 1 month to 2 3/12 years (Group I). In Group I, a younger age of the onset, a long period of disturbed consciousness and a high activity of CSF neuron-specific enolase (NSE) was associated with refractory epilepsy. The other five patients had continuous seizures from the acute phase of encephalitis without a latent period (Group II). They had more than 2 types of partial motor seizures which occurred frequently during the acute phase of encephalitis. The NSE activity in the CSF of patients in Group II was less than 50 ng/ml, being similar to those in Group III. The epilepsy in Group II, however, was the most refractory. The reason for the development of this continuous refractory epilepsy remained obscure.

Acute Disease↗
PubMed1999

Novel organization and sequences of five genes encoding all six enzymes for de novo pyrimidine biosynthesis in Trypanosoma cruzi.

A 25 kb segment of genomic DNA from Trypanosoma cruzi, the causative agent of Chagas' disease, was sequenced. It contains five genes, pyr1, pyr2, pyr3, pyr4, and pyr6-5, encoding all six enzymes involved in de novo pyrimidine biosynthesis, glutamine-dependent carbamoyl-phosphate synthetase, aspartate carbamoyltransferase, dihydroorotase, dihydroorotate dehydrogenase, and orotidine-5'-phosphate decarboxylase linked with orotate phosphoribosyltransferase, respectively. The pyr genes constitute a polycistronic transcription unit on an 800 kb chromosomal DNA in the order of pyr1, pyr3, pyr6-5, pyr2, and pyr4 from the 5' terminus, with intervening sequences of 2.2, 0.4, 8.1, and 0.8 kb. The amino acid sequences deduced from the trypanosomatid pyr genes, except for pyr6, showed closer similarities to mammalian and yeast sequences, and less similarity to archaeal and bacterial sequences. The last two enzymes encoded by a single gene, pyr6-5, are covalently linked in the order opposite to mammalian pyr5-6, and possess a putative glycosomal targeting signal tripeptide, serine-lysine-leucine, at the C terminus. The calculated isoelectric points of 9.3 and 9.9 are also diagnostic of the glycosomal localization of these enzymes. We conclude that the T. cruzi pyr gene organization represents an early progenitor in de novo pyrimidine biosynthesis in eukaryotic lineage, and that the independent pyr genes may have evolved before the gene fusion events that resulted in the three mammalian-type genes, pyr1-3-2, pyr4, and pyr5-6, for UMP synthesis. Peculiarities in the trypanosomatid pyr6-5 gene product are discussed.

Amino Acid Sequence↗
PubMed1999

Isolation of a LIM15/DMC1 homolog from the basidiomycete Coprinus cinereus and its expression in relation to meiotic chromosome pairing.

The Escherichia coli gene recA is essential for homologous recombination and DNA repair, and homologs have been identified in eukaryotes. A basidiomycete, Coprinus cinereus, which has many advantages for the study of meiosis, was recently reported to have a homolog of one of these, RAD51. In the yeast Saccharomyces, mutations in the RAD51 gene cause defects in both somatic and meiotic cells. Based on this finding, we screened for a meiosis-specific homolog of recA, equivalent to Lilium LIM15 or Saccharomyces DMC1, in C. cinereus, and isolated a clone containing a 1.2-kb DNA fragment from a cDNA library constructed with Coprinus poly(A)+ RNA isolated from cells undergoing meiosis. The predicted amino acid sequence was 52% identical to the putative gene product of the lily cDNA clone LIM15 and 61% identical to Saccharomyces DMC1, and showed limited sequence similarity to the products of RAD52, 55, and 57. The synchrony of meiosis in Coprinus provides an ideal system for the investigation of differential gene expression in relation to meiosis and fruiting body development. Northern analysis indicated that Coprinus LIM15/DMC1 was expressed at meiotic prophase within 8 h after the onset of karyogamy, suggesting that the gene functions mostly at the stage at which the homologous chromosomes pair, but may not be essential at the point at which they recombine. The gene is not expressed in somatic cells.

Amino Acid Sequence↗
PubMed1999

Intrathecal co-administration of NMDA antagonist and NK-1 antagonist reduces MAC of isoflurane in rats.

BACKGROUND: Intravenous administration of N-methyl-D-aspartate (NMDA) receptor antagonists and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor antagonists reportedly reduce the minimum alveolar anaesthetic concentration (MAC) for inhalation anaesthetics. If pain perception can be prevented by the intrathecal administration of antinociceptive receptor antagonists, these agents may reduce the requirements for inhalation anaesthetics. We studied the effect of intrathecal administration of an AMPA/kainate receptor antagonist, a metabotropic glutamate (mGlu) receptor antagonist and co-administration of NMDA and a neurokinin-1(NK-1) receptor antagonist drugs at low doses on the MAC. METHODS: After Wistar rats (n=36) were fitted with indwelling intrathecal catheters, the MAC of isoflurane was determined following intrathecal administration of a non-NMDA receptor antagonist (CNQX) at 10 microg, a mGlu receptor antagonist (AP3) at 10 microg, or a combination of NMDA receptor antagonist (APV) at 0.01 microg to 1 microg with NK-1 receptor antagonist (CP96345, CP) at 0.1 microg to 10 microg. Subsequently, a reversal dose of intrathecal NMDA with substance P (SP) was administered, and the MAC of isoflurane was redetermined. Conscious rats (n=15) were also examined for the presence of locomotor dysfunction following the intrathecal co-administration of APV and CP. RESULTS: Neither CNQX nor AP3 reduced the MAC of isoflurane. APV at 0.01 microg plus CP at 1 microg, as well as APV at 0.1 microg plus CP at 10 microg, reduced the MAC of isoflurane, with respective reductions of 7.6% and 14%; (P<0.05). Co-administration of NMDA plus SP reversed the decrease in the MAC of isoflurane. Locomotive activity was not changed. CONCLUSIONS: The NMDA receptor and the NK-1 receptor are important determinants of the MAC of isoflurane, exerting this influence by inhibition of pain transmission in the spinal cord, while mGlu and AMPA receptors have no effect on the MAC of isoflurane.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1999

The effect of intrathecal magnesium sulphate on nociception in rat acute pain models.

We examined the antinociceptive effect of intrathecally administered magnesium sulphate (MgSO4) in rats, using acute pain models including mechanical pressure, heat and subcutaneous formalin injection. According to the locomotion test 10 microliters of 6.2% MgSO4 did not produce motor paralysis. At the same dose, responses to pressure and heat were intact, compared with controls given saline. MgSO4 produced depression of pain responses only after the first 10 min in the formalin test. Our studies indicated that MgSO4 did not show remarkable antinociceptive effects in acute pain models.

Acute Disease↗
PubMed1999

Conversion of a bacterial warm sensor to a cold sensor by methylation of a single residue in the presence of an attractant.

The aspartate chemoreceptor (Tar) of Escherichia coli also serves as a thermosensor, and it is very amenable to genetic and biochemical analysis of the thermosensing mechanism. Its thermosensing properties are controlled by reversible methylation of the cytoplasmic signalling/adaptation domain of the protein. The unmethylated and the fully methylated (aspartate-bound) receptors sense, as attractant stimuli, increases (warm sensor) and decreases (cold sensor) in temperature respectively. To learn more about the mechanism of thermosensing, we replaced the four methyl-accepting glutamyl residues with non-methylatable aspartyl residues in all possible combinations. In a strain defective in both methyltransferase (CheR) and methylesterase (CheB) activities, all of the mutant Tar proteins functioned as warm sensors. To create a situation in which all of the remaining glutamyl residues were methylated, we expressed the mutant proteins in a CheB-defective, CheR-overproducing strain. The fully glutamyl-methylated proteins were designed to mimic the full range of methylation states possible for wild-type Tar. Almost all of the methylated mutant receptors, including those with single glutamyl residues, were cold sensors in the presence of aspartate. Thus, binding of aspartate to Tar and methylation of its single glutamyl residue can invert its temperature-dependent signalling properties.

Aspartic Acid↗
PubMed1999

Induction of CD8+ T cell-mediated protective immunity against Trypanosoma cruzi.

Trypanosoma cruzi was transformed with the Plasmodium yoelii gene encoding the circum-sporozoite (CS) protein, which contains the well-characterized CD8+ T cell epitope, SYVPSAEQI. In vivo and in vitro assays indicated that cells infected with the transformed T. cruzi could process and present this malaria parasite-derived class I MHC-restricted epitope. Immunization of mice with recombinant influenza and vaccinia viruses expressing the SYVPSAEQI epitope induced a large number of specific CD8+ T cells that strongly suppressed parasitemia and conferred complete protection against the acute T. cruzi lethal infection. CD8+ T cells mediated this immunity as indicated by the unrelenting parasitemia and high mortality observed in immunized mice treated with anti-CD8 antibody. This study demonstrated, for the first time, that vaccination of mice with vectors designed to induce CD8+ T cells is effective against T. cruzi infection.

Animals↗
PubMed1999

[Childhood multiple sclerosis and allied demyelinative diseases].

We report five cases of multiple sclerosis (MS) and three cases of allied demyelinative diseases starting during childhood. Three of the MS patients presented with atypical initial symptoms, such as acute encephalitis or myelitis, making an early clinical diagnosis difficult. Ophthalmologic symptoms were noted in four of MS children, and in two with allied demyelinative diseases. Therefore, if a child shows ophthalmologic symptoms (i.e. optic neuritis, ophthalmoplegia), brain magnetic resonance imaging (MRI) should be conducted for the differential diagnosis of MS and other demyelinative diseases. Cerebrospinal fluid analysis is not useful for the initial diagnosis of MS, because pleocytosis and increase of oligoclonal IgG band in cerebrospinal fluid are seen in both MS and other demyelinative disorders. However, neuron specific enolase (NSE) is slightly higher in the latter than in the former. T2-weighted MRI of multiple sclerosis showed multiple high intensity areas in the white matter of the cerebrum and cerebellum, capsula interna, and crus cerebri etc. Most of these lesions were clinically silent, being characteristic of MS. In two MS cases, however, initial MRI revealed no abnormal findings. Thus, the diagnosis of MS can not be made by initial MRI only.

Biomarkers↗
PubMed1999

[Lissencephaly type I: electroencephalographic findings and neuroradiological classification].

Lissencephaly type I is a diffuse type of migration disorder that contains agyria and/or pachygyria on the brain surface. We experienced 5 cases of this disease and evaluated their electroencephalographic findings and seizure types based on the neuroradiological classification of lissencephaly. Ages at seizure onset ranged from 2 months to 4 months (mean 3.2 months). The patients with complete agyria had generalized tonic seizures, and those with pachygyria partial seizures or tonic spasms. The characteristic findings of complete agyria in electroencephalogram were high-voltage alfa activity. The amount of high-voltage slow waves increased with the ratio of pachygyria on the brain surface. The appearance of multifocal spikes and sharp waves suggested irregular arrangement of pachygyria on the brain surface.

Brain↗
PubMed1999

[Topography and number of cortical tubers in tuberous sclerosis: comparison between patients with and without West syndrome].

To reveal the role of cortical tubers in the pathophysiology of West syndrome associated with tuberous sclerosis, we studied their numbers and topography, focusing on the differences between patients with infantile spasms and without infantile spasms. We reviewed the clinical date on the seizure types, seizure evolution and developmental status of 13 patients: 8 patients with infantile spasms (the West syndrome group) and 5 patients without infantile spasms (the non-West syndrome group). The number, size and location of the cortical tubers were evaluated on 5 mm-thick T2-weighted MR images. The average number of cortical tubers of the West syndrome group was 11.4 per patient, being larger than that of the non-West syndrome group (7.8). The West syndrome group included two patients with only one tuber. The average number of the cortical tubers in the occipital lobes of the West syndrome group was 2.4, which was larger than that of the non-West syndrome group (0.8). From these results, a large number of cortical tubers, which suggest involvement of larger cerebral cortical regions, increase the possibility of the West syndrome in patients with tuberous sclerosis. On the other hand, some patients with only one or few cortical tubers developed West syndrome, which may suggest the presence of a region critical on the development of West syndrome. Our results also suggest that lesions in the occipital lobes might be more significant than those in other lobes. However, the results of this study are diverse, to some extent, which may have resulted from variable epileptogenicity of the cortical tubers. It is necessary to conduct further study, including a greater number of patients, to reveal topographic pathophysiology in West syndrome.

Cerebral Cortex↗
PubMed1999

[Morphometric development and the variability of neurons of the human auditory system: ventral cochlear nucleus and superior medial olivary nucleus].

The development of the human ventral cochlear and medial superior olivary nuclei was studied. We made serial sections of the brain in 10 fetuses at 16-40 weeks of gestation (WG), an infant at 2 months of age and an adult of 63 years using an electronic planimeter with a computer. Although the shape of neurons of the two nuclei was different, our morphometric analysis showed that the development of both of them accelerates between 18 and 21 WG in terms of the columnar length and volume, neuronal size and circularity ratio and the amount of Nissl bodies increases gradually.

Cochlear Nucleus↗
PubMed1998

Carbamoyl-phosphate synthetase II in kinetoplastids.

Genes for carbamoyl-phosphate synthetase II (CPS II), the first enzyme of de novo pyrimidine biosynthesis, were cloned from kinetoplastids, Trypanosoma cruzi and Leishmania mexicana. T. cruzi CPS II gene encodes a protein of 1524 amino acids that encompasses the glutaminase and CPS domains, but incorporates neither aspartate carbamoyltransferase nor dihydroorotase. The residue corresponding to lysine 993 of Escherichia coli CPS, a residue that characterizes the CPS inhibited by UMP and that is replaced by tryptophan in those inhibited by UTP, is in kinetoplastids a hydrophilic glutamine, in line with the preferential inhibition by UDP of kinetoplastid CPS II.

Amino Acid Sequence↗
PubMed1998

Electron microscopic examination of oligocilia in naevus of Ota.

The structure of the cilia present in dermal melanocytes of 14 patients with naevus of Ota was examined by electron microscopy. Cilia and basal bodies were found in 10 and 9 lesions, and in 39 and 18 dermal melanocytes, respectively. In each case, 1-12 cells with a single cilium or multiple cilia were observed. In a total of 3 dermal melanocytes from 2 cases, two cilia per cell were observed. The cilia contained 7, 6, 5 and 4 pairs of doublet microtubules in the periphery and no central microtubule. Another pattern with several pairs of doublet microtubules in the periphery and one or two centrally located doublet microtubules were also observed. The latter were not bona fide central microtubules but one and two doublets, which seemed to be displaced to the centre from the periphery of the cilium.

Adolescent↗
PubMed1998

Early intervention for very-low-birth-weight infants.

To assess the efficacy of early intervention (EI) for very-low-birth-weight (VLBW) infants, we evaluated 62 2 year old children who were enrolled in an EI program and 48 control subjects aged 2 years. We determined the subjects' developmental quotients (DQ) and obtained information about the parents' evaluation of the children from a questionnaire sent to the parents. There was no significant difference in the DQ between the EI group and the control group. However, based on the responses to the questionnaire, subjects in the EI group showed slight, but statistically marginally significant, improvements in behavioral problems, especially a decrease in hyperkinesia, in adjusting to a circadian sleep cycle, and an improvement in language development, as compared with the control group (P < 0.1). Thus, EI for VLBW infants is considered useful to enhance some areas of development.

Child Behavior↗
PubMed1998

High predictive value of red cell volume measurement using carboxy-haemoglobin in a rabbit model of haemorrhage.

We have studied the accuracy of blood volume measurements using carbon monoxide (CO)-labelled haemoglobin (COHb) injection and dilution (CO method) by comparing changes in red cell volume (RCV) measured using the CO method and 51Cr-labelled erythrocyte dilution (51Cr method) in a haemorrhage and infusion model in rabbits. RCV was measured repeatedly using the CO method at four different blood volume stages (stages I-IV). At stages I and IV, RCV was measured simultaneously using the 51Cr method. In comparing the sum of the circulating RCV and extracted RCV (SUM RCV) using the CO method, the values were almost equal and there were no significant differences between the values at the four stages. In comparing circulating RCV measured using the CO method and the 51Cr method, mean difference between the two methods was 0.80 (SD 0.76) ml kg-1 or 4.7 (4.6)%, and a positive correlation was observed (r = 0.91). We conclude that the CO method can be used to measure blood volume during perioperative periods in infants because it avoids use of a radioactive tracer, is simple and repeated measurements are possible.

Animals↗
PubMed1998

Effects of orally ingested Bifidobacterium longum on the mucosal IgA response of mice to dietary antigens.

To study the effects of lactic acid bacteria on the mucosal defence against dietary protein antigens, we compared the mucosal IgA responses to beta-lactoglobulin (beta-LG) of two groups of mice fed a whey protein diet with and without a culture condensate of Bifidobacterium longum. Both total IgA and anti-beta-LG IgA levels in tissue extracts of the small intestinal wall were significantly higher in mice fed the B. longum diet for 2 weeks than in control ones. Peyer's patch (PP) cells from B. longum-fed mice had a much larger increase in in vitro IgA production than ones from control mice. Furthermore, the in vitro IgA response to beta-LG was detected only when PP cells from B. longum-fed mice were assayed. These results suggest that orally ingested lactic acid bacteria may protect a host from invasion of the intestinal mucosa by dietary antigens that have escaped enzymatic digestion in the intestine.

Animal Feed↗