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Y Koyama

Publications and source records attributed to Y Koyama.

At least 55 records · Page 3Linked to original sources
PubMed2001

Apoptosis induction associated with cell cycle dysregulation by rice bran agglutinin.

Effects of rice bran agglutinin (RBA) on human monoblastic leukemia U937 cells were examined in comparison with those of wheat germ agglutinin (WGA) and Viscum album agglutinin (VAA). These lectins inhibit cell growth, and several lines of evidence indicate that the growth inhibition is caused by the induction of apoptosis. We observed that RBA induces chromatin condensation, externalization of membrane phosphatidylserine, and DNA ladder formation, features of apoptosis. DNA ladder formation was inhibited by a general inhibitor against caspases, which are known to play essential roles in apoptosis. Flow cytometric analysis revealed that RBA and WGA cause G2/M phase cell cycle arrest with increased expression of Waf1/p21, while cell cycle arrest was not observed for VAA. These data indicate that RBA induces apoptosis associated with cell cycle arrest in U937 cells, and suggest that the induction mechanism for RBA is similar to that for WGA, but different from that for VAA.

Apoptosis↗
PubMed2001

Purification and characterization of the recombinant Thermus sp. strain T2 alpha-galactosidase expressed in Escherichia coli.

The nucleotide sequence of the Thermus sp. strain T2 DNA coding for a thermostable alpha-galactosidase was determined. The deduced amino acid sequence of the enzyme predicts a polypeptide of 474 amino acids (M(r), 53,514). The observed homology between the deduced amino acid sequences of the enzyme and alpha-galactosidase from Thermus brockianus was over 70%. Thermus sp. strain T2 alpha-galactosidase was expressed in its active form in Escherichia coli and purified. Native polyacrylamide gel electrophoresis and gel filtration chromatography data suggest that the enzyme is octameric. The enzyme was most active at 75 degrees C for p-nitrophenyl-alpha-D-galactopyranoside hydrolysis, and it retained 50% of its initial activity after 1 h of incubation at 70 degrees C. The enzyme was extremely stable over a broad range of pH (pH 6 to 13) after treatment at 40 degrees C for 1 h. The enzyme acted on the terminal alpha-galactosyl residue, not on the side chain residue, of the galactomanno-oligosaccharides as well as those of yeasts and Mortierella vinacea alpha-galactosidase I. The enzyme has only one Cys residue in the molecule. para-Chloromercuribenzoic acid completely inhibited the enzyme but did not affect the mutant enzyme which contained Ala instead of Cys, indicating that this Cys residue is not responsible for its catalytic function.

Amino Acid Sequence↗
PubMed2001

Conflict and integration of spatial attention between disconnected hemispheres.

OBJECTIVES: To clarify how the disconnected hemispheres perceive a line and bisect it with successful or unsuccessful integration of spatial attention. METHODS: Eye movements were recorded when a patient with an extensive callosa infarction bisected horizontal lines. The lesion extended into the left cingulate gyrus. RESULTS: When the patient bisected lines with the right hand, the gaze was initially directed rightward and shifted further to the right side with the execution of manual response, which resulted in rightward errors. Shortly after bisection, rapid ocular searches occurred to the left side, whereas the rightward errors did not decrease throughout the trials. When using the left hand, there was no deviation of the gaze before presentation of lines. In the first few trials, the patient bisected the line with a leftward error and then searched rapidly to the right side. The subsequent bisections were almost accurate, as the subjective midpoint was placed near the point of the initial fixation that fell around the true centre. Ocular searching was mostly absent during and after line bisection. CONCLUSIONS: In callosa disconnection, left unilateral spatial neglect may appear when use of the right hand induces a rightward bias in the attentional control of the left hemisphere and damage to its cingulate gyrus inhibits interhemispheric integration of attention. Resultant rightward errors of line bisection often cause interhemispheric conflict of attention, as the right hemisphere perceives the longer extent on the left side. By contrast, the disconnected but intact right hemisphere may bisect a line accurately by integrating attention to the extents perceived in the left and right visual fields.

Attention↗
PubMed2001

Role of carotid bodies in control of the neuroendocrine response to exercise.

This study was aimed at assessing the role of carotid body function in neuroendocrine and glucoregulatory responses to exercise. The carotid bodies and associated nerves were removed (CBR, n = 6) or left intact (Sham, n = 6) in anesthetized dogs >16 days before experiments, and infusion and sampling catheters were implanted. Conscious dogs were studied at rest and during 150 min of exercise. Isotopic dilution was used to assess glucose production (R(a)) and disappearance (R(d)). Arterial glucagon was reduced in CBR compared with Sham at rest (29 +/- 3 vs. 47 +/- 3 pg/ml). During exercise, glucagon increased more in Sham than in CBR (47 +/- 9 vs. 15 +/- 2 pg/ml). Cortisol and epinephrine levels were similar in the two groups at rest and during exercise. Basal norepinephrine was similar in CBR and Sham. During exercise, norepinephrine increased by 432 +/- 124 pg/ml in Sham, but by only 201 +/- 28 pg/ml in CBR. Basal arterial plasma glucose was 108 +/- 2 and 105 +/- 2 mg/dl in CBR and Sham, respectively. Arterial glucose dropped by 10 +/- 3 mg/dl at onset of exercise in CBR (P < 0.01) but was unchanged in Sham (decrease of 3 +/- 2 mg/dl, not significant). Basal glucose kinetics were equal in Sham and CBR. At onset of exercise, R(a) and R(d) were transiently uncoupled in CBR (i.e., R(d) > R(a)) but were closely matched in Sham. In steady-state exercise, R(a) and R(d) were closely matched in both groups. Insulin was equal in the basal period and decreased similarly during exercise. These studies suggest that input from the carotid bodies, or receptors anatomically close to them, 1) is important in control of basal glucagon and the exercise-induced increment in glucagon, 2) is involved in the sympathetic response to exercise, and 3) participates in the non-steady-state coupling of R(a) to R(d), but 4) is not essential to glucoregulation during sustained exercise.

Animals↗
PubMed2001

Apoptosis-inducing activity of a driselase digest fraction of green tea residue.

We enzymatically digested green tea residue with Driselase, a crude preparation containing cellulase, pectinase and proteases, in order to examine the potential usefulness of the residue. A fraction of the digest soluble in 70% ethanol was found to induce the death of U937 human histiocytic lymphoma cells by apoptosis. Other enzyme preparations gave similar products with cell death-inducing activity of varing potency. The green tea residue may therefore be a useful source of potential agents with anti-cancer activity.

Antineoplastic Agents, Phytogenic↗
PubMed2001

Apoptosis-inducing activity of high molecular weight fractions of tea extracts.

High molecular weight fractions of green tea, black tea, oolong tea, and pu-erh tea were found to induce apoptosis in human monoblastic leukemia U937 cells by examination of their ability to inhibit cell proliferation and to induce apoptotic body formation and DNA ladder formation. These tea fractions were also shown to induce apoptosis in stomach cancer MKN-45 cells. In addition to known antitumor-promoting activity of tea high molecular weight fractions, their apoptosis-inducing activity may contribute to cancer chemopreventive effects of tea.

Apoptosis↗
PubMed2001

Transient absorption from the 1Bu+ state of all-trans-beta-carotene newly identified in the near-infrared region.

We have attempted subpicosecond time-resolved absorption spectroscopy of all-trans-beta-carotene in organic solvents in the 820-1060 nm region and found novel transient absorption features which lived in subpicosecond time scales. A first component that appeared immediately after excitation showed a lifetime of 190 +/- 10 fs in n-hexane in agreement with the 1Bu+ lifetime that had been determined by fluorescence upconversion spectroscopy (195 +/- 10 fs). (Kandori et al. [1994] J. Am. Chem. Soc. 116, 2671-2672.) Therefore, this component is assigned to a transient absorption from the 1Bu+ state.

Carbon Disulfide↗
PubMed2001

Time-dependent changes in the carotenoid composition and preferential binding of spirilloxanthin to the reaction center and anhydrorhodovibrin to the LH1 antenna complex in Rhodobium marinum.

Carotenoids were isolated from the cells of Rhodobium marinum, and their structures were determined by mass spectrometry and 1H nuclear magnetic resonance spectroscopy; the carotenoids include lycopene, rhodopin, anhydrorhodovibrin, rhodovibrin and spirilloxanthin. Time-dependent changes in the carotenoid composition in the reaction center (RC) and the light-harvesting complex 1 (LH1) were traced by high-performance liquid chromatography analysis of the extracts. The carotenoid composition changed according to the spirilloxanthin biosynthetic pathway. However, spirilloxanthin having the longest conjugated chain was always preferentially bound to the RC, and anhydrorhodovibrin and other precursors to the LH1.

Alphaproteobacteria↗
PubMed2001

Immunolocalization of aquaporin-8 in rat digestive organs and testis.

Expression of aquaporin-8 mRNA has previously been shown in hepatocytes, pancreatic acinar cells, colon epithelial cells and seminiferous tubules of the testis in the rat by in situ hybridization technique. However, immunolocalization of this water channel has not yet been demonstrated. In the present study, the localization of immunoreactive aquaporin-8 and expression of the mRNA were examined in rat organs (cerebrum, cerebellum, eye, salivary gland, heart, lung, liver, pancreas, esophagus, stomach, jejunum, ileum, colon, testis, ovary, kidney, spleen and lymphnode) by immunohistochemistry using an antibody against aquaporin-8 and ribonuclease protection assay. Aquaporin-8 was distinctly immunolocalized on the apical membranes of pancreatic acinar cells and mucosal epithelium of the colon and jejunum. In the liver, the bile canalicular membrane of hepatocytes was immunostained. In the testis, immunoreactive aquaporin-8 was demonstrated on the luminal side of the seminiferous tubules. At high magnification, the peroxidase reaction products appeared on the ramified cytoplasmic membrane of Sertoli cells surrounding the residual bodies or spermatogenic cells. Specificity of the antibody was verified by Western blot analysis showing a minor approximately 28 kDa band (deduced deglycosylated form of aquaporin-8) and a major approximately 30 kDa band (glycosylated form) in these organs. The intensity of aquaporin-8 immunoreactivity was approximately comparable to that of aquaporin-8 mRNA expression in the liver, pancreas, colon, jejunum and testis. The aquaporin-8 mRNA expression in the hepatocytes was presumed to be closely associated with the structure of bile canaliculi since the message was detected in hepatocytes immediately after isolation from the liver but not in cells following cultivation for three days. The localization of immunoreactive aquaporin-8 indicated functions for this water channel in the secretion of bile and pancreatic juice, and the secretion or absorption of water in the colon and jejunum, and the maturation or liberation of spermatogenic cells in the testis.

Animals↗
PubMed2001

Immunolocalization of aquaporin-9 in rat hepatocytes and Leydig cells.

The aquaporin (AQP)-9 gene was recently isolated from human and rat liver cDNA libraries as a member of the water channel family for water and neutral solutes. Although the expression of AQP9 mRNA has been demonstrated in several organs including the liver and testis by Northern blot analysis, the cellular and subcellular localization of the AQP9 protein remains unclear. In the present light and electron microscopic immunohistochemical study, the localization of the AQP9 immunoreactivity was examined in fifteen kinds of rat organs using an antibody against rat AQP9 synthetic peptide. The antibody immunostained a major band of approximately 33 kDa in the liver by Western blot analysis. Immunoreactivity for AQP9 was found exclusively in the liver and testis among the organs examined. In the liver, positive staining appeared selectively along the space of Disse. Immunoelectron microscopy confirmed the localization of AQP9 on the surface of hepatocyte microvilli facing the space of Disse. In the testis, the plasma membrane of Leydig cells located between seminiferous tubules was conspicuously immunoreactive to the antibody. Intense mRNA expression was detected in the liver and testis but not in other organs by ribonuclease protection assay. These findings suggest a specific role for AQP9 in the transport of water and non-charged solutes in hepatocytes and Leydig cells.

Animals↗
PubMed2001

Ingestion of gelatin has differential effect on bone mineral density and body weight in protein undernutrition.

Malnutrition, particularly protein undernutrition, contributes to the occurrence of osteoporotic fracture by lowering bone mass. In this study, the effects of dietary protein on bone mineral density and body weight in protein undernutrition were compared between gelatin and milk casein. When mice were fed for 10 wk with a low protein diet containing 10(%) casein or 6% casein +4% gelatin, there was no significant difference in the final body weight between the 6% casein+4% gelatin group and the 10% casein group. In contrast, bone mineral content and bone mineral density of the femur were significantly higher in the 6% casein+4% gelatin group than in the 10% casein group. Bone mineral content and bone mineral density did not differ significantly in 14% protein groups between 14% casein and 6% casein +80% gelatin. These results suggest that gelatin has differential effects on bone mineral density and body weight in protein undernutrition.

Animals↗
PubMed2001

[Broad old anteroseptal myocardial infarction with coronary aneurysm showing marked improvement of myocardial perfusion by intravenous myocardial contrast echocardiography after successful coronary angioplasty: a case report].

A 56-year-old man with old anteroseptal myocardial infarction was admitted to treat a gradually expanding coronary aneurysm. Coronary angiography demonstrated the aneurysm and delayed flow in the left coronary descending artery. The aneurysm was successfully treated with stenting. Technetium-99m-sestamibi single photon emission computed tomography (SPECT) showed a persistent defect in the anterior infarcted area after stenting. Myocardial contrast echocardiography was performed using SystemFIVE and EchoPAC. Levovist was injected (1 ml, 1.5 ml/sec; bolus + 1 ml/sec; continuous infusion) by Pulsar. Myocardial reperfusion was observed by B-mode and anatomical M-mode before and after intervention. Time-intensity curves from the region of interest positioned within the interventricular septum showed the mean value at plateau increased from 10.8 to 25.1 dB. The persistent defect area demonstrated by SPECT was enhanced by myocardial contrast echocardiography after intervention. Myocardial contrast echocardiography is useful for the assessment of outcome after intervention and evaluation of improved coronary blood flow.

Angioplasty, Balloon, Coronary↗
PubMed2001

[Vesicorectal fistula due to pelvic foreign body: a case report].

We report a case of vesicorectal fistula caused by a pelvic foreign body. An 84-year-old woman presented with urinary tract infection and bladder stone. During transurethral lithotripsy, a foreign body was observed in the stone. CT and colonoscopy revealed a vesicorectal fistula due to a foreign body. After continuous bladder washout over a period of one month, resection of the foreign body, fistulectomy, and sigmoidostomy were performed. The foreign body was suspected to be a medical mesh from a sling operation. After the surgery, the patient's course was uneventful. This is the second patient with vesicointestinal fistula due to a foreign body in the Japanese literature.

Aged↗
PubMed2001

Expression and localization of angiogenic inhibitory factor, chondromodulin-I, in adult rat eye.

PURPOSE: To determine the role in the eye of chondromodulin (ChM)-I, which has been identified in cartilage as an angiogenic inhibitor, the expression and localization and a possible function of ChM-I were investigated. METHODS: Expression and localization of ChM-I in rat eyes were examined by RNase protection assay and in situ hybridization and by immunostaining, using an antibody against a synthetic peptide. The effect of recombinant ChM-I on tube morphogenesis of retinal endothelial cells was examined in culture. RESULTS: The rat ChM-I gene was determined to encode the open reading frame of 334 amino acid residues, and ChM-I mRNA was exclusively expressed in cartilage, eye, and cerebellum in rats. ChM-I mRNA expression was evident in the iris-ciliary body, retina, and scleral compartments, but not in other compartments of the eye. In situ hybridization revealed mRNA expression in the ganglion cells, inner nuclear layer cells, and pigment epithelium in the retina and in the nonpigment epithelium of the ciliary body. Immunoreactive ChM-I was present in these cells and also in the vitreous body. Western blot analysis detected an approximately 25-kDa band of ChM-I presumed as a secretory form in the aqueous humor and vitreous body and an approximately 37-kDa band as a precursor form in the retina. Recombinant human ChM-I inhibited tube morphogenesis of human retinal endothelial cells in vitro. CONCLUSIONS: These observations indicate a potential role for ChM-I in inhibition of angiogenesis in the rat eye.

Amino Acid Sequence↗
PubMed2001

[Intermittent administration of 5-FU and isovorin to patients with advanced and recurrent colon cancer].

We attempted a new regimen of intermittent administration of 5-FU and low-dose Isovorin (F.I) to four patients with advanced and recurrent colon cancer. A partial response (PR) was achieved in two of four patients who had evaluable lesions for this treatment. We observed few side effects among these patients. Only one patient among four showed grade 1 neuropathy after two administrations of this chemotherapy. However, after a two-week pause in administration, the neuropathy disappeared and we could continue the therapy. This patient with multiple liver metastases achieved a partial response. Other patients had no side effects such as bone marrow suppression or digestive symptoms. This intermittent F.I treatment might be an effective and promising therapy with few side effects even for patients with poorer conditions.

Aged↗
PubMed2001

[Cadaveric renal transplantation for Goodpasture's syndrome: a case report].

A 19-year-old man with a history of histologically-proven Goodpasture's syndrome (hemoptysis, rapidly progressive glomerulonephritis, and positive anti-glomerular basement membrane (anti-GBM) antibody) was maintained on hemodialysis for 21 months. After steroid pulse therapy and plasmapheresis, his anti-GBM antibody disappeared. His stable condition on dialysis and a session of plasmapheresis prior to surgery allowed him to undergo cadaveric renal transplantation from a 34-year-old man. The blood type was identical (group A and Rh (+)), and there was 1 and 0 mismatch of HLA class 1 and 2, respectively. The initial immunosuppressants included cyclosporine, methylprednisolone, mizoribine, azathioprine, and anti-lymphocyte globulin (ALG). The transplanted kidney regained function on day 6 and he was free from hemodialysis. Circulating anti-GBM antibody was negative after surgery. The graft has functioned well for almost 4 years after transplantation without any episodes of renal or pulmonary complications. To the best of our knowledge, this is the first report of renal transplantation for Goodpasture's syndrome in the Japanese literature.

Adult↗