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Biomedical subjects

H Kumagai

Publications and source records attributed to H Kumagai.

At least 37 records · Page 2Linked to original sources
PubMed2001

Enzymatic syntheses of T antigen-containing glycolipid mimicry using the transglycosylation activity of endo-alpha-N-acetylgalactosaminidase.

Thomsen-Friedenreich antigen (T antigen) disaccharide, beta-D-galactose-(1-->3)-alpha-N-acetyl-D-galactosamine (beta-D-Gal-(1-->3)-alpha-D-GalNAc), containing glycolipid mimicry was synthesized using the transglycosylation activity of endo-alpha-N-acetylgalactosaminidase from Bacillus sp. This enzyme could transfer the disaccharide from a p-nitrophenyl substrate to water-soluble 1-alkanols and other alcohols at a transfer ratio of 70% or more. Although the transfer ratios were lower for water-insoluble than water-soluble alcohols, they were shown to increase by adding sodium cholate to the reaction mixtures. The enzyme also transferred the disaccharide directly from asialofetuin to 1-alkanols. The anomeric bond between the disaccharide and 1-alkanols of the transglycosylation product is in the alpha configuration as determined by sequential digestion of jack bean beta-galactosidase and Acremonium alpha-N-acetylgalactosaminidase. Since the transglycosylation product, beta-D-Gal-(1-->3)-alpha-D-GalNAc-(1-->O)-hexyl, efficiently inhibits the binding of anti-T antigen monoclonal antibody to asialofetuin, it has potential as an agent for blocking T antigen-mediated cancer metastasis.

Alcohols↗
PubMed2001

Thymic carcinoids in multiple endocrine neoplasia-type 1.

We report a case of a 45-year-old man with thymic carcinoids in multiple endocrine neoplasm-type 1. Extended total thymectomy was performed through a median sternotomy, and the mediastinal regional lymph nodes and fibroadipose tissue were dissected. Multiple endocrine neoplasm-type 1 related thymic carcinoids are rare and have a poor prognosis. The efficacy of radiotherapy and chemotherapy for prolonging survival is limited, and an aggressive surgical approach with complete excision of the tumor with resection of the peripheral tissues and dissection of the mediastinal lymph nodes seems to be the best available treatment today. We have found that this practice of thymectomy at an early stage in combination with genetic and effective radiological treatment can be effective for multiple endocrine neoplasm-type 1 patients.

Carcinoid Tumor↗
PubMed2001

Brain perfusion measured by flow-sensitive alternating inversion recovery (FAIR) and dynamic susceptibility contrast-enhanced magnetic resonance imaging: comparison with nuclear medicine technique.

The aim of this study was to compare cerebral perfusion images and regional cerebral blood flow (rCBF) of SPECT study with the images and regional intensity of relative cerebral blood flow (CBF) images acquired by contrast-enhanced perfusion MR imaging (pMRI) and flow-sensitive alternating inversion recovery (FAIR). Twelve patients with various cerebral diseases were underwent I-123-IMP SPECT, pMRI, and FAIR studies to measure rCBF. A total of 12 regions of interest (ROI) were created over cerebrum and cerebellum to acquire the corresponding rCBF from I-123-IMP study and regional average signal intensity from CBF images of pMRI and FAIR studies. Left-to-right (L/R) and cerebral-to-cerebellar (CCR) ratios were created from the rCBF of I-123-IMP and signal intensity of CBF images of pMRI and FAIR. Image quality of FAIR was the poorest among all; however, CBF images of pMRI and FAIR images show comparatively decreased intensity at the corresponding site of decreased perfusion on I-123-IMP images. Both FAIR and pMRI images showed high intensity along the sinuses, choroid plexus, and large vessels in sulci. No significant correlation was found among all imaging modalities. But L/R ratio of I-123-IMP showed significant correlation with those of pMRI and FAIR, but for CCR, significant correlation was observed only between I-123-IMP and FAIR. Perfusion images of both pMRI and FAIR may produce images comparable to SPECT study. But to calculate absolute CBF more easy-to-apply and accurate algorithms are needed to overcome the artifacts from large vessels.

Adult↗
PubMed2001

High-output heart failure caused by a huge renal arteriovenous fistula after nephrectomy: report of a case.

Postnephrectomy renal arteriovenous fistula (AVF) with an aneurysmal lesion is a rare clinical entity that may cause high-output heart failure. In this report, we describe the case of a 68-year-old man who had undergone nephrectomy for renal tuberculosis 43 years previously, in whom an acquired large renal AVF presenting as an aneurysm caused congestive cardiac failure. We also discuss the hemodynamic, hormonogenic (human arterial natriuretic polypeptide; hANP), and radiographic findings before and after surgery for the AVF. The AVF with an aneurysmal lesion was clearly visualized by three-dimensional-computerized tomographic (CT) scanning, and proximal ligation of the renal artery was followed by an uneventful recovery. This procedure can produce good results when a fistula is too large to allow safe embolization and when excision would be hazardous due to inflammation surrounding the fistula.

Aged↗
PubMed2001

Dominant effect of supplemented-sucrose on the low protein diet-induced increase in blood pressure of Sprague-Dawley rats.

A low-protein diet (LPD) is known to affect the regulation of hemodynamics, and could contribute to the genesis of hypertension. We investigated the mechanism for the LPD-induced elevation of blood pressure in 52 Sprague-Dawley rats. Rats fed the LPD for 8 weeks showed a significantly higher blood pressure than those fed on a normal-protein diet (NPD) when the LPD included sucrose as a predominant component of carbohydrate (LPD with a high sucrose content, 135 +/- 2 mmHg; NPD, 124 +/- 2 mmHg; p<0.05). However, LPD with a low sucrose content, in which corn starch was the main component of carbohydrate, did not have a hypertensive effect (125 +/- 2 mmHg). Urinary epinephrine and norepinephrine excretion was significantly higher in the LPD high-sucrose group than in the NPD and LPD low-sucrose groups, and there was a significant positive correlation between urinary norepinephrine excretion and systolic blood pressure. Urinary nitric oxide excretion was no different between these groups, and 2 % L-arginine administration exerted no antihypertensive effect on the LPD-induced elevation of blood pressure. Sodium restriction also did not attenuate the LPD-induced elevation of blood pressure. These results suggest that the effect of LPD on blood pressure could be interpreted as the effect of the high sucrose content supplemented to the LPD rather than the direct effect of protein restriction, and that the stimulation of sympathetic nervous activity was associated with this elevation of blood pressure.

Animals↗
PubMed2001

High-resolution elemental mapping of titanium oxide/aluminium oxide multilayer by spectrum-imaging.

A spectrum-imaging technique based on scanning transmission electron microscopy combined with an electron energy-loss spectroscopy has been applied for the multilayer of amorphous titanium oxide and aluminium oxide layers on silicon substrate. We demonstrate the high-resolution elemental mapping and discuss the advantage of this method compared to an energy-filtering transmission electron microscopy. The main advantage is the absence of chromatic broadening, which allows the use of a large collection angle to acquire spectrum-image data and a wide energy window to integrate the core-loss signals. This suggests that the spatial resolution of elemental maps is mainly determined by the size of the electron probe.

Journal Article↗
PubMed2001

Apoptotic epithelial cells in biopsy specimens from infants with streaked rectal bleeding.

BACKGROUND: Histologic studies of rectosigmoidal mucosal biopsies of infants with isolated blood-streaked stool have shown many eosinophils and revealed aggregates of small dark granules (nuclear dust). However, no description of the nuclear dust has been made for this condition and the nature of the nuclear dust has not been thoroughly investigated. We determined the characteristics of these particles in biopsies from infants with streaked rectal bleeding. METHODS: Nineteen infants who were younger than 6 months old and had isolated rectal bleeding were studied, as were six age-matched control infants. Rectosigmoidal mucosal biopsies were immunohistochemically assessed using anticarcinoembryonic antigen and macrophage-associated antibodies and examined for apoptotic cells by modified in situ TdT-mediated dUTP-biotin nick-end labelling. The number of apoptotic epithelial cells was compared between rectal bleeding and control groups. RESULTS: Immunohistochemistry showed that at least some of the nuclear dust consisted of apoptotic epithelial cells. Infants with rectal bleeding also showed nodular lymphoid hyperplasia (n = 16), abundant eosinophils (>20/high power field, n = 14) in the mucosa, and a significantly high number of apoptotic epithelial cells relative to the control group. Rectal bleeding disappeared at 6-month follow-up in 14 of 18 infants (one was lost to follow-up) who were fed a different milk formula or breast-fed (their mothers were restricted from having cow's milk and eggs). CONCLUSIONS: The high number of apoptotic epithelial cells in rectosigmoidal mucosal biopsies of infants with streaked rectal bleeding is probably caused by accelerated epithelial cell turnover and apoptosis.

Apoptosis↗
PubMed2001

Cloning of a gene encoding a highly stable endo-beta-1,4-glucanase from Aspergillus niger and its expression in yeast.

A gene encoding an endo-beta-1,4-glucanase, which is highly resistant to high temperature, protease and surfactant treatment, was isolated from Aspergillus niger IFO31125 and designated as eng1. The deduced amino acid sequence encoded by eng1 showed high homology with the sequence of a not-well-characterized cellulase encoded by eglB which has not yet been shown to be a stable enzyme. To confirm the sequence of the gene encoding the highly stable endo-beta-1,4-glucanase, the cloned gene was expressed in the yeast Saccharomyces cerevisiae, in which no cellulase activity was found, and the gene product was purified and subjected to enzymatic characterization. The enzyme retained 56% of the initial activity after 1 h of incubation at 80 degrees C and was stable in the range of pH 3.0-10.0. The optimal temperature for enzyme activity was 70 degrees C and the optimal pH was 6.0. The enzyme was highly protease-resistant and retained more than 80% of the initial activity after protease treatment for 3 d at 40 degrees C. The enzyme was also resistant to various surfactants. From these results, eng1 was confirmed to encode a very stable endo-beta-1,4-glucanase.

Journal Article↗
PubMed2001

Purification and characterization of aminopeptidase B from Escherichia coli K-12.

Aminopeptidase B, which is one of the four cysteinylglycinases of Escherichia coli K-12, was purified to electrophoretic homogeneity and its enzymatic characteristics were observed. Aminopeptidase B was activated by various divalent cations such as Ni2+, Mn2+, Co2+, and Cd2+, and lost its activity completely on dialysis against EDTA. This indicates that aminopeptidsase B is a metallopeptidase. It was stabilized against heat in the presence of Mn2+ or Co2+. The activity of aminopeptidase B, which was saturated with one of above divalent cations, was enhanced on the addition of a very small amount of a second divalent cation. Alpha-glutamyl p-nitroanilide, leucine p-nitroanilide, and methionine p-nitroanilide were good substrates for aminopeptidase B, while native peptides, cysteinylglycine and leucylglycine, were far better substrates. The kcat/Km for cysteinylglycine was much bigger than those for leucylglycine or leucine p-nitroanilide.

Aminopeptidases↗
PubMed2001

Determination of hydrogen peroxide by iron(III) complex of thiacalix[4]arenetetrasulfonate on a modified ion-exchanger with peroxidase-like catalytic activity.

An iron(III) complex of thiacalix[4]arenetetrasulfonate on a modified anion-exchanger (Fe3+-TCAS(A-500)) has shown high peroxidase-like activity at pH 5 - 6 for the reaction of quinoid-dye formation between 3-methyl-2-benzothiazolinone hydrazone and N-(3-sulfopropyl)aniline in the presence of hydrogen peroxide. Utilizing the peroxidase-like activity of Fe3+-TCAS(A-500) for this reaction, a method using Fe3+-TCAS(A-500) was applied for the spectrophotometric determination of hydrogen peroxide. The calibration curve by the method using Fe3+-TCAS(A-500) was linear over the range from 1 to 10 microg of hydrogen peroxide in a 1 ml sample solution. The apparent molar absorptivity for hydrogen peroxide was 2.4 x 10(4) l mol(-1) cm(-1). which was about 80% of that by peroxidase under the same conditions. This determination method of hydrogen peroxide using Fe3+-TCAS(A-500) was applied for the determination of glucose in diluted normal and abnormal control serum I and II.

Calibration↗
PubMed2001

Synthesis and biological evaluation of cytogenin derivatives.

To enhance the stability in vivo, new derivatives of cytogenin were synthesized, and their biological activity and stability in mice were estimated. 2-(8-Hydroxy-6-methoxy-1-oxo-1H-2-benzopyran-3-yl)propionic acid (NM-3) was found to be the most stable among them. It modified collagen-induced arthritis in mice. It also showed potent anti-angiogenic activity in a mouse dorsal air sac assay.

Animals↗
PubMed2001

Mitral valve plasty for mitral regurgitation after blunt chest trauma.

A 21 year-old woman was admitted to our hospital because of chest and back pain after blunt chest trauma. On admission, consciousness was clear and a physical examination showed labored breathing. Her vital signs were stable, but her breathing gradually worsened, and artificial respiration was started. The chest roentgenogram and a subsequent chest computed tomographic scans revealed contusions, hemothorax of the left lung and multiple rib fractures. A transthoracic echocardiography (TTE) revealed normal left ventricular wall motion and mild mitral regurgitation (MR). TTE was carried out repeatedly, and revealed gradually progressive MR and prolapse of the posterior medial leaflet, although there was no congestive heart failure. After her general condition had recovered, surgery was performed. Intraoperative transesophageal echocardiography (TEE) revealed torn chordae at the posterior medial leaflet. The leaflet where the chorda was torn was cut and plicated, and posterior mitral annuloplasty was performed using a prosthetic ring. One month later following discharge, the MR had disappeared on TTE.

Accidents, Traffic↗
PubMed2001

[A case of carcinosarcoma of the lung].

A 63-year-old man was admitted to our hospital because of cough and slight fever up. A tumor shadow in right S6 and obstructive pneumonia was detected by X-ray and CT. Bronchoscopic study showed that right B6 bronchous was occluded by the tumor and in which malignant cell (squamous cell carcinoma suspect) were detected. Therefore right middle and lower lobectomy was performed. Histological examination of the resected specimen showed that the tumor was composed of poorly differentiated squamous cell carcinoma and abnormal spindle cell component. Both components of the tumor were mixed each other in part. Immunohistologically, malignant cell of sarcomatous elements were positively stained by vimentin and actine, but was not found such as osteosarcoma or rabdomyosarcoma. He was diagnosed as so-called carcinosarcoma of the lung.

Carcinosarcoma↗
PubMed2000

A novel low-density lipoprotein receptor-related protein mediating cellular uptake of apolipoprotein E-enriched beta-VLDL in vitro.

We report here the identification of a novel member of the low-density lipoprotein receptor (the LDL receptor) family through signal sequence trap screening of a mouse lymphocyte cDNA library. The protein was termed LDL receptor-related protein 9 (LRP9). LRP9 is a type I membrane protein predicted to contain 696 amino acids with a calculated molecular mass of 74 764 Da. The NH(2)-terminal half of LRP9 contains two CUB domains separated by a single ligand-binding repeat. The second CUB domain is followed by a cluster of three additional ligand-binding repeats and a transmembrane domain. The COOH-terminal intracellular region contains a proline-rich region. LRP9 mRNA was expressed in the liver, kidney, lung, and heart at high levels, and in the spleen and brain at low levels. In situ hybridization analysis of mouse liver, kidney, and brain detected LRP9 transcripts in hepatocytes, sinusoidal lining cells, peritubular capillaries, choroid plexus, ependyma of the third ventricle, pia matter, and hippocampus. In particular, high levels of expression were observed in the vascular walls. Apolipoprotein E (apoE)-enriched beta-VLDL stimulated cellular cholesteryl ester formation in ldl-A7/LRP9. These results raise the possibility that this newly identified receptor, which is expressed in the liver, may play a physiological role in the uptake of apoE-containing lipoproteins.

Adult↗
PubMed2000

Molecular cloning of cDNA encoding alpha-N-acetylgalactosaminidase from Acremonium sp. and its expression in yeast.

Alpha-N-acetylgalactosaminidase (alpha-GalNAc-ase; EC 3.2.1.49) is an exoglycosidase specific for the hydrolysis of terminal alpha-linked N-acetylgalactosamine in various sugar chains. The cDNA, nagA, encoding alpha-GalNAc-ase from Acremonium sp. was cloned, sequenced, and expressed in yeast Saccharomyces cerevisiae. The nagA contains an open reading frame which encodes for 547 amino acid residues including 21 residues of a signal peptide in its N-terminal. The calculated molecular mass of mature protein from the deduced amino acid sequence of nagA is 57260 Da, which corresponds to the value obtained from SDS-PAGE of native and recombinant enzymes treated with endo-beta-N-acetylglucosaminidase H. The amino acid sequence of NagA showed significant similarity to those of eukaryotic alpha-GalNAc-ases and alpha-galactosidases (alpha-Gal-ases), particularly alpha-Gal-ase A (AglA) from Aspergillus niger. Phylogenetic analysis revealed that NagA does not belong to the cluster of vertebrate alpha-GalNAc-ase and alpha-Gal-ase but forms another cluster with AglA and yeast alpha-Gal-ases. Thus, the evolutionary origin of the fungal alpha-GalNAc-ase is suggested to be different from that of vertebrate alpha-GalNAc-ase. This is the first report of a microbial alpha-GalNAc-ase gene.

Acremonium↗
PubMed2000

Three types of putative presympathetic neurons in the rostral ventrolateral medulla studied with rat brainstem-spinal cord preparation.

To study the electrophysiological properties of presympathetic neurons in the rostral ventrolateral medulla (RVLM), intracellular recordings were performed by the whole-cell patch-clamp technique. We utilized the neonatal rat brainstem-spinal cord preparation, in which the sympathetic neuronal network is thought to be preserved, unlike in slice preparation. In response to stimulation in the ipsilateral Th2 spinal segment including intermediolateral cell column (IML), 33 of 151 non-respiratory RVLM neurons showed antidromic action potentials with a constant latency of 45 ms, and can be considered as presympathetic neurons. We classified and characterized the RVLM presympathetic neurons into three types: 'regularly firing neurons (n=7)', which showed ramp depolarization and frequent action potentials (4.2+/-0.9 spikes/s) with rare excitatory postsynaptic potentials (EPSPs); 'irregularly firing neurons (n=21)', which exhibited many EPSPs that modulated the firing rate; and 'silent-type neurons (n=5)', which discharged action potentials only during current-induced depolarization. Lucifer-Yellow staining showed that the irregularly firing neurons were significantly larger and had more dendrites than the regularly firing neurons. All regularly firing neurons retained their discharges during low-Ca2+ -high-Mg2+ superfusion that blocks synaptic input, whereas the discharges in 11 of 16 irregularly firing neurons were abolished, suggesting that the regularly firing neurons discharged independently of synaptic input. Seven of 31 RVLM neurons were hyperpolarized by stimulation of vagal afferent nerves. In summary, three types of RVLM presympathetic neurons were characterized by the patch-clamp technique in the brainstem-spinal cord preparation, in which the connection was preserved from vagal afferent to the Th2 spinal segment through the RVLM. Since antidromic action potentials were demonstrated by stimulation in the Th2 spinal segment in 33 neurons of all three types, all types of RVLM neurons constitute a part of the sympathetic neuronal network.

Action Potentials↗