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Biomedical subjects

Y Nagata

Publications and source records attributed to Y Nagata.

At least 361 records · Page 20Linked to original sources
PubMed1993

GD2 ganglioside on human T-lymphotropic virus type I-infected T cells: possible activation of beta-1,4-N-acetylgalactosaminyltransferase gene by p40tax.

Ganglioside expression on adult T-cell leukemia (ATL) and human T-cell lymphotropic virus type I (HTLV-I)-infected cells was determined by using a panel of monoclonal antibodies. ATL lines and HTLV-I-infected cells specifically expressed GD2. Leukemia cells from ATL patients generally expressed low levels of GD2 but the percentage of GD2+ cells increased up to 40-70% after in vitro culture in the presence of interleukin 2 for about a week. No other type of leukemia cells and normal peripheral T cells expressed GD2 during in vitro culture under the same conditions. The appearance of GD2 in the cultured ATL cells corresponded with the expression of p40tax, a product of the HTLV-I gene. Peripheral lymphocytes infected with a p40tax-expressing retroviral vector expressed high levels of GD2 in comparison with control lymphocytes containing the neomycin-resistance gene alone. The apparently increased levels of beta-1,4-N-acetylgalactosaminyltransferase (GM2/GD2 synthase) mRNA in these cells were demonstrated by reverse transcription-polymerase chain reaction analysis. Concordance between mRNA expression for the HTLV-I tax1/rex1 genes and the beta-1,4-N-acetylgalactosaminyltransferase gene was also observed in uncultured ATL cells. These results suggest that high GD2 expression was due to neosynthesis from precursor GD3 by increased expression of this enzyme induced by p40tax in vitro and in vivo.

Base Sequence↗
PubMed1993

Selective alterations in transglutaminase activity of rat superior cervical ganglia in response to neurotransmitters, high potassium and sialic acid-containing compounds.

We examined the in vitro effects of neurotransmitters, high KCl as well as sialic acid-containing compounds (GM1; SC) on transglutaminase (TG) activity in isolated superior cervical ganglia (SCG) one week after denervation or axotomy. Following denervation, TG activity in SCG decreased to 83% of the unoperated control value, whereas that of axotomized ganglia was 28% of control. Thus, TG activity was relatively unaffected when sympathetic ganglionic neurons were preserved, but was markedly reduced under conditions where neurons were degenerating. Addition of ACh (0.1 mM) to the medium during aerobic incubation stimulated TG activity more than 3-fold in denervated ganglia but had no effect on TG activity in axotomized ganglia. Similarly, the NE (0.05 mM)-induced decrease of TG activity observed in intact SCG was also seen following denervation (-49%) but not following axotomy. In denervated SCG, the stimulatory effects of ACh were virtually abolished by co-addition of the cholinergic antagonists, atropine or hexamethonium, while the suppressant effects of NE were blocked by the adrenergic antagonists, propranolol, prazosin or yohimbine. These results imply that transmitter-induced rapid changes in TG activity occur predominantly in ganglionic neurons. When the ganglia were depolarized by high KCl (50 mM), a significant increase in TG activity in each intact, denervated and axotomized SCG was seen with qualitatively similar manner, suggesting that high KCl-induced depolarization affects both neuronal and glial components in the SCG. The marked increase in ganglionic TG activity in response to GM1 (5 nM) and synthetic SC (0.02 mM) were lost in denervated SCG but only partially reduced in axotomized SCG.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1993

Liquid chromatography-mass spectrometry for the determination of medetomidine and other anaesthetics in plasma.

A liquid chromatographic-atmospheric pressure chemical ionization mass spectrometric method is presented for the simultaneous determination of medetomidine and other anaesthetic drugs in solutions and dog plasma. The drugs examined were flumazenil, butorphanol, atropine, ketamine, xylazine, medetomidine, atipamezole and midazolam. The separation was carried out on a reversed-phase column using methanol-0.1 M ammonium acetate (3:2) as eluent.

Anesthetics↗
PubMed1993

Determination of acidic saponins in crude drugs by high-performance liquid chromatography on octadecylsilyl porous glass.

High-performance liquid chromatographic (HPLC) analysis on octadecylsilyl porous glass was investigated for acidic saponins in ginseng, bupleurum root and senega. The acidic saponins, malonyl-ginsenosides, malonyl-saikosaponins and senegins, as well as neutral saponins in the crude drugs were separated rapidly by HPLC on this column with aqueous acetonitrile containing KH2PO4 as the mobile phase at room temperature.

Carbohydrate Sequence↗
PubMed1993

Effect of unilateral motor cortex ablation on activity of choline acetyltransferase and levels of amino acid transmitter candidates in the spinal cord of adult monkeys.

Evidence that L-glutamate is a neurotransmitter of corticofugal fibers was sought by measuring changes in several biochemical markers of neurotransmitter function in discrete regions of spinal cord after ablation of sensorimotor cortex in monkeys. One and five weeks after unilateral cortical ablation, samples from six areas of spinal cord (ventral, lateral and dorsal regions of the left and right sides) were analysed for choline acetyltransferase (ChAT) activity and contents of amino acid transmitter candidates-glutamic acid (Glu), aspartic acid (Asp), glycine (Gly), taurine (Tau) and gamma-aminobutyric acid (GABA). During one to five weeks after unilateral cortical ablation of the monkey, prolonged hemiplegia in the contralateral side was observed. Histological examination of the spinal cord 5 weeks after unilateral (left) cortical ablation showed no apparent change in either control (ipsilateral, left) or affected (contralateral, right) sides of the cord as examined by the Klüver-Barrera method. The ChAT activity as a cholinergic marker was scarcely changed in any region of either left (control) or right (affected) side of the spinal cord at one and five weeks after unilateral (left side) ablation of the motor cortex. Amino acid levels in each region of the spinal cord were not significantly changed one week after unilateral ablation of the motor cortex. However, a significant decrease of Glu content was observed in the lateral column of the affected (right) side compared to the control (left) side of cervical and lumbar cord five weeks after cortical ablation of the left motor area. No concomitant alterations of other amino acids were detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1993

Mechanism of acute deterioration of the neurological status following rapid and massive intraluminal thrombosis in case of a giant intracavernous carotid artery aneurysm: demonstration by MR imaging.

A case is reported of a thrombosed giant aneurysm of the intracavernous carotid artery. Transient neurological deterioration was attributable to the acute swelling of the aneurysmal mass after rapid and massive intraluminal thrombosis. Characteristics on the magnetic resonance imaging of this case are reported and discussed.

Acute Disease↗
PubMed1993

Rapid and transient alterations in transglutaminase activity in rat superior cervical ganglia following denervation or axotomy.

The activity of transglutaminase (TG), a Ca(2+)-dependent enzyme contributing to cross-linkage formation of intracellular polypeptide chains decreased rapidly to ca. 25% of control level in superior cervical ganglia (SCG) within 0.5 h following denervation. The reduced level was maintained for at least 24 h. By contrast, following axotomy, ganglionic TG activity increased by ca. 50% within 1 h, maintained the increase to 4 h, and returned to control level by 24 h. When SCG were transferred to aerobic in vitro incubation conditions 3 h following denervation, the addition of the protein kinase C (PKC) inhibitor, trifluoperazine (TFP, 10 micrograms/ml), to the medium partially reversed the denervation-induced reduction in ganglionic TG activity. Addition of a PKC activator, 12-O-tetradecanoylphorbol 13-acetate (TPA, 1 microM), had no effect on the TG activity. These findings suggest that the pathway resulting in the rapid, denervation-induced inhibition of TG activity may involve the transsynaptic activation of PKC. When SCG were placed in vitro 3 h following axotomy, addition of nerve growth factor (NGF, 0.25 micrograms/ml) to the medium reversed approximately one-half of the axotomy-induced increase in TG activity. Thus, following axotomy, the reduction in delivery to the SCG of NGF, which can be transported retrogradely within the axon and is indispensable for morphological and functional survival of sympathetic neurons, may trigger the transient, axotomy-induced TG activation in the SCG.

Animals↗
PubMed1993

Conservative treatment of burst fractures of the thoracolumbar and lumbar spine.

Twenty-three patients with burst fracture of the thoracolumbar and lumbar spine were treated nonoperatively. Among these 23 patients, 13 had a neurological deficit and 10 patients did not have such a deficit. Union of burst fractures occurred with conservative treatment in 22 out of 23 patients, but late operation was necessary in only one patient, who had an increasing kyphotic deformation. Of the 13 patients with neurological deficit, 8 showed full recovery and none had neurological deterioration. It was observed by CT scans that the narrowing of the spinal canals was progressively relieved by natural remodelling of the fragments retropulsed into the spinal canal.

Adolescent↗
PubMed1993

Detection of point mutations in the Kirsten-ras oncogene provides evidence for the multicentricity of pancreatic carcinoma.

It has been reported that multicentricity of pancreatic carcinomas extending beyond the pancreatic duct occur in 15% to 40% of patients. This has been difficult to confirm, however, with currently available histologic techniques. Mutations in the Kirsten (Ki)-ras oncogene, which can be detected frequently in pancreatic carcinomas using the polymerase chain reaction (PCR), may serve as a potential clonal marker of the cancer cells. Fifty-three patients with a histopathologic diagnosis of pancreatic carcinoma were selected for the determination of certain Ki-ras mutations through PCR. The authors identified mutations in the Ki-ras codon 12 in 46 of 53 tumors. Two of these 46 tumors had two different mutations to aspartic acid (GAT) and to valine (GTT) in Ki-ras codon 12. Another isolate had an additional mutation in Ki-ras codon 13. The detection of different mutations in the same tumor suggests that there may be multicentricity in pancreatic carcinomas and that its frequency may be as low as 6% of the carcinomas. These results imply that total pancreatectomy for eliminating tumor recurrence due to multicentricity may not be warranted.

Adenocarcinoma↗
PubMed1993

Isolated lateral traumatic dislocation of the radial head in a boy: case report.

Lateral traumatic dislocation of the radial head occurred in a 9-year-old boy with cubitus varus. Reduction of the dislocation and immobilization of the arm in flexion and supination in a plaster cast for 4 weeks were done and after 6 months the boy returned to school, with no problems in daily living.

Biomechanical Phenomena↗
PubMed1993

Cloning and sequencing of a dehalogenase gene encoding an enzyme with hydrolase activity involved in the degradation of gamma-hexachlorocyclohexane in Pseudomonas paucimobilis.

In Pseudomonas paucimobilis UT26, gamma-hexachlorocyclohexane (gamma-HCH) is converted by two steps of dehydrochlorination to a chemically unstable intermediate, 1,3,4,6-tetrachloro-1,4-cyclohexadiene (1,4-TCDN), which is then metabolized to 2,5-dichloro-2,5-cyclohexadiene-1,4-diol (2,5-DDOL) by two steps of hydrolytic dehalogenation via the chemically unstable intermediate 2,4,5-trichloro-2,5-cyclohexadiene-1-ol (2,4,5-DNOL). To clone a gene encoding the enzyme responsible for the conversion of the chemically unstable intermediates 1,4-TCDN and 2,4,5-DNOL, a genomic library of P. paucimobilis UT26 was constructed in Pseudomonas putida PpY101LA into which the linA gene had been introduced by Tn5. An 8-kb BglII fragment from one of the cosmid clones, which could convert gamma-HCH to 2,5-DDOL, was subcloned, and subsequent deletion analyses revealed that a ca. 1.1-kb region was responsible for the activity. Nucleotide sequence analysis revealed an open reading frame (designated the linB gene) of 885 bp within the region. The deduced amino acid sequence of LinB showed significant similarity to hydrolytic dehalogenase, DhlA (D. B. Janssen, F. Pries, J. van der Ploeg, B. Kazemier, P. Terpstra, and B. Witholt, J. Bacteriol. 171:6791-6799, 1989). The protein product of the linB gene was 32 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Not only 1-chlorobutane but also 1-chlorodecane (C10) and 2-chlorobutane, which are poor substrates for other dehalogenases, were good substrates for LinB, suggesting that LinB may be a member of haloalkane dehalogenases with broad-range specificity for substrates.

Amino Acid Sequence↗
PubMed1993

Turner syndrome and occlusion of the internal carotid artery.

A 2-year-old girl with Turner syndrome was admitted with left hemiplegia and left facial palsy. Serial cranial computed tomographic scan demonstrated multiple cerebral infarctions in the right putamen and right medial cortical areas. Single photon emission computed tomographic scan revealed hypoperfusion from the right frontal to the right temporal area. Right carotid angiography showed narrowing and occlusion of the right internal carotid artery at the sphenoidal portion. Collateral circulation was not detected between the external and internal carotid arteries. Left carotid angiography revealed that the left anterior artery was narrow, and that the left internal carotid artery provided blood to the right internal carotid artery through the anterior communicating artery. These findings suggested that the cerebrovascular abnormality might be due to congenital hypoplasia of arteries in this patient. The unusual combination of cerebral infarction and Turner syndrome was reported.

Arterial Occlusive Diseases↗
PubMed1993

Aneurysmal rupture during angiography.

The aim of the present study was to analyze the clinical data on rebleeding in cerebral aneurysms during angiography and to evaluate the importance of the time interval between the latest rupture and angiography. Fourteen personal cases and 202 patients reported in the literature are reviewed. Rebleeding during angiography occurred most often (78%) on Day O; 89% bled when angiography was performed within 6 hours of the latest rupture. The prognosis in such ruptures was poor, with a mortality of 79%. Intentional delay in angiography of at least 6 hours from the latest rupture is recommended if the associated hematoma is not large.

Adult↗
PubMed1993

Evaluation of intravascular hemolysis by haptoglobin administration after prosthetic valve replacement.

Although the measurement of serum haptoglobin (S-Hp) is of great use for evaluation of intravascular hemolysis, it is not applicable in patients with mechanical prosthetic valves because S-Hp is virtually absent. We administered haptoglobin preparation to 10 patients with Björk-Shiley mitral prosthetic valves and 10 patients with the same aortic prosthetic valves. Serum haptoglobin levels were measured periodically afterwards. The maximum haptoglobin levels (Hp (max)), serum, haptoglobin reducing rate ((Hp-delta Hp)/delta t) and expected haptoglobin disappearing time (hours) were obtained from the subsequent samples. The screening studies which were performed at the same time were not predictors of difference in the 2 groups. On the other hand, serum haptoglobin reducing rate and expected haptoglobin disappearing time indicated that hemolysis is higher in patients with an aortic prosthetic valve than with a mitral prosthetic valve. This haptoglobin administration test seems to be useful for the comparative examination of the intravascular hemolysis caused by the difference in the position of the prosthetic valve.

Adult↗
PubMed1993

Isolation and characterization of Tn5-induced mutants of Pseudomonas paucimobilis UT26 defective in gamma-hexachlorocyclohexane dehydrochlorinase (LinA).

Pseudomonas paucimobilis UT26 grows on gamma-hexachlorocyclohexane (gamma-HCH) as a sole source of carbon and energy. Tn5 mutation was introduced into UT26, and two kinds of mutants defective in gamma-HCH degradation were phenotypically isolated; one (UT64) completely lacked the activity to degrade gamma-HCH, while the other (UT61) retained a very low level of activity. Tagging and sequencing analysis showed that both mutants had a Tn5 insertion at the same site of the linA (gamma-HCH dehydrochlorinase encoding) gene. However, UT61 had an additional rearrangement, which could be the cause of its retaining a low level of activity. An in vitro complementation test with a crude extract from UT64 plus partially purified LinA protein showed that LinA was essential not only for the first-step reaction (gamma-HCH to gamma-pentachloro-cyclohexene; gamma-PCCH), but also for the second-step reaction (gamma-PCCH to compound B) of gamma-HCH degradation in UT26.

Amino Acid Sequence↗
PubMed1993

Isolation and identification of canine plasma components suspected as uremic toxins.

Suspected uremic substances contained in four fractions, which had been selected as the suspected canine uremic peaks in the previous study, were isolated by two stages of preparative liquid chromatography (PLC) from plasma of uremic dogs treated with the ligation of the ureter, and then their physicochemical properties were examined. The primary separation of the suspected uremic peaks were performed with the same anion exchange resin as used in the analytical HPLC in the previous study. Analytical reverse phase HPLC showed that three of 4 suspected uremic peaks almost consisted of single substances, but the other contained several substances. Main subfractions of these peaks were successfully isolated by the secondary stage reverse phase PLC. By means of thin layer chromatography, ultraviolet absorption spectrometry and proton-nuclear magnetic resonance spectroscopy, components of 4 main peaks were confirmed to be small molecules such as a pyridine derivative, uric acid, hippuric acid and kynurenic acid, respectively.

Animals↗