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Biomedical subjects

N Takeda

Publications and source records attributed to N Takeda.

At least 307 records · Page 17Linked to original sources
PubMed1994

Detection of ribose-methylated nucleotides in Pyrodictium occultum tRNA by liquid chromatography--frit-fast atom bombardment mass spectrometry.

Ribose-methylated dinucleotides of the type NmpN' derived from digestion of tRNA with RNase T2 were separated and characterized by directly combined liquid chromatography--mass spectrometry (LC-MS) with a continuous-flow frit-fast atom bombardment (frit-FAB) interface. Prediction of NmpN' peaks was readily made by comparison of the LC profile with that of comparative nuclease P1 digest. The identity of the candidate peaks including NmpN' was further recognized by the mass spectra, in which NmpN' showed intense molecular-related ions, in addition to sequence-specific fragment ions, to verify the chemical structures in both positive- and negative-ion modes. The method was applied to screening NmpN' (and NmpN' mpN") in tRNA from the extremely thermophilic archaeon Pyrodictium occultum.

Archaea↗
PubMed1994

Parthenogenetic activation of oocytes in c-mos-deficient mice.

In Xenopus the c-mos proto-oncogene product (Mos) is essential for the initiation of oocyte maturation, for the progression from meiosis I to meiosis II and for the second meiotic metaphase arrest, acting as an essential component of the cytostatic factor CSF. Its function in mouse oocytes is unclear, however, as is the biological significance of c-mos mRNA expression in testes and several somatic tissues. We have generated c-mos-deficient mice by gene targeting in embryonic stem cells. These mice grew at the same rate as their wild-type counterparts and reproduction was normal in the males, but the fertility of the females was very low. The c-mos-deficient female mice developed ovarian teratomas at a high frequency. Oocytes from these females matured to the second meiotic metaphase both in vivo and in vitro, but were activated without fertilization. The results indicate that in mice Mos plays a role in the second meiotic metaphase arrest, but does not seem to be essential for the initiation of oocyte maturation, spermatogenesis or somatic cell cycle.

Animals↗
PubMed1994

Expression of GABAA receptor gamma 1 and gamma 2 subunits in the peripheral vestibular system of the rat.

The distribution of GABAA receptor gamma 1 and gamma 2 subunits in the rat vestibular ganglion cells and end-organs was examined by using immunohistochemical techniques. Both gamma 1 and gamma 2 subunit-like immunoreactivities were observed in most vestibular ganglion cell bodies and peripheral terminal endings in the vestibular sensory epithelia. These results indicate that GABAA receptors are expressed in the vestibular afferent terminal endings and therefore suggest that GABA in addition to glutamate is a neurotransmitter which effects on vestibular afferents.

Afferent Pathways↗
PubMed1994

Simultaneous determination of 13-cis- and all-trans-retinoic acids and retinol in human serum by high-performance liquid chromatography.

A simple and accurate method was developed for the simultaneous determination of 13-cis- and all-trans-retinoic acid (13cRA, tRA), and retinol (ROH) in human serum using isocratic high-performance liquid chromatography (HPLC). The serum sample (0.2 ml) was diluted with 2 ml of acetonitrile-100 mM ammonium acetate (1:3, v/v), pH 5.5, and extracted with 5 ml of n-hexane. The extract was analyzed on an ODS column with a mobile phase consisting of 70 vols. of acetonitrile-methanol (2:1) and 30 vols. of 100 mM ammonium acetate, pH 7.0, at 50 degrees C. The retinoids were detected at 340 nm. Average recoveries were 88.4% for 13cRA, 82.5% for tRA at fortification levels of 5, 10 and 25 ng/ml, and 84.8% for ROH at 550 ng/ml. Within-day precision for normal human serum samples was 4.7% for 13cRA, 11.9% for tRA and 3.7% for ROH, and between-day precision was 10.4%, 14.2% and 4.7%, respectively. The limit of determination was 0.5 ng/ml in serum for the RAs. Mean concentration in 20 human sera was found to be 1.80 ng/ml for 13cRA, 1.77 ng/ml for tRA, and 487 ng/ml for ROH.

Acetates↗
PubMed1994

Occurrence of galanin-like immunoreactivity in vestibular and cochlear efferent neurons after labyrinthectomy in the rat.

The origins of the vestibular and cochlear efferent systems lie in the lower brainstem and innervate the labyrinth. In the present study we investigated the changes in galanin-like immunoreactivity (GAL-IR) in the vestibular and cochlear efferent neurons in control and labyrinthectomized rats. In control animals, no GAL-IR was noticed in these neurons. However, in response to unilateral labyrinthectomy, similar GAL-IR was bilaterally expressed in the two systems. GAL-immunostained cells appeared on postoperative day 3 and reached a peak of intensity and number at postoperative week 2. Retrograde tracing by fluorogold combined with GAL immunohistochemistry demonstrated that, except for the cells of the contralateral lateral superior olivary nucleus (LSO), GAL-IR neurons project into the lesioned labyrinth.

Animals↗
PubMed1994

Endogenous synthesis of N-methylnorsalsolinol in rat brain during in vivo microdialysis with epinine.

The in vivo metabolic pathway for the synthesis of N-methylnorsalsolinol, an analogue of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), was studied in the rat brain. N-Methyldopamine (epinine) was perfused at the striatum of the rat brain by in vivo microdialysis. N-Methylnorsalsolinol (NMNSAL) was identified in the brain dialysate after epinine perfusion using gas chromatography-selected-ion monitoring mass spectrometry (GC-SIM-MS). We demonstrated that NMNSAL could be synthesized from epinine with an aldehyde by the Piclet-Spengler condensation reaction in the rat brain.

Aldehydes↗
PubMed1994

Structural characterization of modified nucleosides in tRNA hydrolysates by frit-fast atom bombardment liquid chromatography/mass spectrometry.

Feasibility for the structural characterization of modified nucleosides in transfer RNA at low microgram levels has been investigated by using continuous-flow frit-fast atom bombardment liquid chromatography/mass spectrometry (frit-FAB LC/MS). Sample of tRNA(Phe) from brewer's yeast (Saccharomyces cerevisiae) was used as a main model, and enzymatically hydrolysed by nuclease P1 and alkaline phosphatase. The resulting nucleoside mixture was separated by using a microbore reversed-phase LC column (150 mm x 0.5 mm i.d.) with an aqueous ammonium acetate-methanol gradient, and the mass spectra were acquired on both positive and negative ionization modes. The modified nucleosides were characterized by comparison of the relative LC elution times with authentic nucleosides, and further confirmed by the structural information from the frit-FAB mass spectra where both molecular and base ions were in general observed as intense peaks in both ionization modes. Typically, 0.06-0.2 A260 units (3-10 micrograms) of isoaccepting tRNA was enough to obtain full-scan mass spectra of modified nucleosides, often occurring at a frequency of one per tRNA molecule using positive ion detection. The LC/MS system was used to screen modified nucleosides in tRNA of the extremely thermophilic microorganism Pyrodictium occultum.

Archaea↗
PubMed1994

Case report 869. Benign metastasizing giant cell tumor of bone.

We presented a case of giant cell tumor of the sacrum with multiple pulmonary metastases in an 11-year-old girl. To the best of our knowledge, our patient is the youngest reported patient with a giant cell tumor with pulmonary metastases. Although giant cell tumor of bone with pulmonary metastases is extremely rare, this entity must be considered in the differential diagnosis of bone tumors.

Child↗
PubMed1994

Early ventriculoperitoneal shunt--effects on learning ability and synaptogenesis of the brain in congenitally hydrocephalic HTX rats.

The learning ability of congenitally hydrocephalic HTX rats in which hydrocephalus had been arrested by the insertion of a V-P shunt 7 days after birth (early shunt) was assessed by means of the light-darkness discrimination test when the animals reached maturity. Early shunt placement resulted in marked reduction in size of abnormally enlarged ventricles and the prevention of both decreasing spine density and decay of synaptic vesicle protein (SVP-38) in the affected cerebral cortex. The learning ability of such animals was also found not to be impaired compared with that of animals in a sham-operation group. On the basis of these investigations, it is concluded that early shunt placement may have a beneficial role in preventing not only impairment of synaptogenesis of the brain by progressing hydrocephalus, but also learning disability. Recent biochemical investigation of the developing brains of hydrocephalic HTX rats revealed problems that cannot be resolved by early shunt insertion, and these are also discussed.

Animals↗
PubMed1994

Thrombin-induced platelet aggregation, phosphoinositide metabolism and protein phosphorylation in NIDDM patients treated by diet, sulphonylurea or insulin.

We studied thrombin-induced metabolism of phosphoinositide, protein phosphorylation and platelet aggregation in platelets from 32 NIDDM patients and 12 control subjects. To clarify the effect of diet, sulphonylureas, or insulin treatment, the subjects were divided into three groups based on the type of treatment. Thrombin-induced platelet aggregation was measured with an aggregometer. Low-dose thrombin (0.25 U/ml)-stimulated platelet aggregation in diabetic patients was significantly increased compared with the control subjects. Platelet aggregation in the sulphonylurea and insulin groups was significantly lower than in the diet group. On the other hand, in platelets incubated with [32P]orthophosphate, thrombin-induced incorporation of 32P radioactivity into phosphatidic acid (PA) was significantly lower in the sulphonylurea and insulin groups than in the diet group. Thrombin-induced incorporation of [32P] radioactivity into phosphatidylinositol (PIP) for 10 s was significantly higher in the sulphonylurea group than in the diet group. There were no differences in thrombin-induced 47 kDa protein phosphorylation between platelets from the diet, sulphonylurea, or insulin groups. These results suggest that sulphonylureas and insulin induce suppression of thrombin-induced activation of phospholipase C, which mediates hydrolysis of PIP and PIP2 and production of PA, which leads to inhibition of platelet aggregation.

Adult↗
PubMed1994

3'-terminal sequence of a small round structured virus (SRSV) in Japan.

We determined the nucleotide sequence of about 1,000 bases from the 3'-terminus of a small round structured virus (SRSV), which caused a gastroenteritis outbreak in Chiba Prefecture, Japan, in 1987. The sequence was compared with the corresponding sequence region of Norwalk virus; it consisted of a part of the open reading frame 2 (ORF2), whole ORF3, and 3'-noncoding region (NCR). The 624-base-long ORF3 had sequence homology of 68% with the corresponding region of Norwalk virus. (The amino acid sequence homology was 74%.) The 94-base-long NCR had 65% homology with Norwalk virus. We then selected two consensus-sequence portions in the above sequence between Chiba and Norwalk viruses for primers in the reverse transcriptase-polymerase chain reaction (RT-PCR). Using this primer set, we detected 669-bp bands in agarose gel electrophoresis of RT-PCR products from feces containing Chiba or Norwalk viruses. Furthermore, in Southern hybridization with Chiba probes which were labeled with digoxigenin-dUTP in PCR, the bands of the two viruses were clearly stained under a low stringency condition. Since both Chiba and Norwalk viruses were detected by the above primer set although they are geographically and chronologically different viruses, our primer-pair may be useful for detection of a broad range of SRSVs which cause gastroenteritis in different areas.

Base Sequence↗
PubMed1994

Two cases of symptomatic interhemispheric arachnoid cyst in the elderly.

We recently experienced two cases of symptomatic interhemispheric arachnoid cyst (IHAC) in the elderly, both extending into the frontoparietal region. Both patients presented with more than an 8-year history of progressive hemiparesis and underwent capsule resection in combination with internal drainage to the pericallosal cistern via the interhemispheric approach. Postoperatively, the cyst cavities were greatly reduced in size, and neurologic signs and symptoms were markedly improved. A discussion of the diagnosis, mechanism of symptom onset, and management of symptomatic IHAC in the elderly is presented.

Aged↗
PubMed1994

Gene regulation of cyclic AMP-dependent protein kinase subunits (C alpha, beta; RI alpha, beta and RII alpha, beta) in rat facial motoneurons after nerve transection.

In this study we investigated the changes in gene expressions of catalytic (C alpha, beta) and regulatory (RI alpha, beta and RII alpha, beta) subunits of cAMP-dependent protein kinase (PKA) in axotomized facial motoneurons of the rat. Nerve transection induced changes in the expression of C subunit messenger RNAs and RII subunit messenger RNAs. Control facial motoneurons had a high expression of both C alpha and C beta subunit messenger RNAs, but their expression declined after axotomy. The decrease was most pronounced at postoperative week 2 and returned to basal level within postoperative week 4. In contrast, the expression of both RII alpha and beta subunit messenger RNAs, which were low in control facial motoneurons, was increased after axotomy. Enhancement of RII subunits messenger RNAs was apparent during postoperative weeks 1 and 3, and then returned to the basal level. RI alpha, beta subunits messenger RNAs were strongly expressed in normal facial motoneurons, but were not clearly influenced by axotomy. These results indicate an attenuation of total PKA activity in axotomized facial motoneurons. Furthermore, such gene regulation may imply a change of the targets for PKA in facial motoneurons during the process of neurite regeneration.

Animals↗
PubMed1994

Up-regulation of GAP-43 (B50/F1) gene expression in vestibular efferent neurons following labyrinthectomy in the rat: in situ hybridization using an alkaline phosphatase-labeled probe.

Growth-associated protein (GAP)-43 plays a significant role in nerve regeneration and synaptic remodeling. We examined the profiles of GAP-43 mRNA expression in vestibular efferent neurons after labyrinthectomy in adult rats, and clearly demonstrated that labyrinthectomy increased GAP-43 expression in these neurons. This finding suggests the ability of vestibular efferent nerves to regenerate after nerve injury.

Alkaline Phosphatase↗
PubMed1994

Serotonin-degradative pathways in the toad (Bufo bufo japonicus) brain: clues to the pharmacological analysis of human psychiatric disorders.

Bufotenine (BUTN) is a hallucinogen with psychotropic effects. High levels of BUTN and its precursor, N-methylserotonin are shown for the first time to occur and to accumulate mainly in the brain during the degradation of serotonin in the central nervous system of the toad, Bufo bufo japonicus. These compounds are concentrated in the hindbrain, which includes the cerebellum and medulla oblongata. BUTN can also be detected in blood and urine specimens from the toad. In humans, autism is a subtype of schizophrenia that appears to be a functional disease of the brain. BUTN can be detected in urine specimens from infant autistic patients. Analysis by three-dimensional HPLC suggests that the presence and levels of BUTN may be important markers for the diagnosis of autism. It appears, therefore, that some aspects of the central nervous system of Bufo may provide useful pharmacological clues to the etiology of human psychiatric diseases, such as autism, that are known to be linked to the methylation of serotonin.

Animals↗