Biomedical subjects

M Yoshimura

Publications and source records attributed to M Yoshimura.

At least 19 recordsLinked to original sources

PubMed1995

Suppression of lung metastasis of B16 mouse melanoma by N-acetylglucosaminyltransferase III gene transfection.

The beta 1-6 structure of N-linked oligosaccharides, formed by beta-1,6-N-acetylglucosaminyltransferase (GnT-V), is associated with metastatic potential. We established a highly metastatic subclone, B16-hm, from low metastatic B16-F1 murine melanoma cells. The gene encoding beta-1,4-N-acetylglucosaminyltransferase (GnT-III) was introduced into the B16-hm cells, and three clones that stably expressed high GnT-III activity were obtained. In these transfectants, the affinity to leukoagglutinating phytohemagglutinin was reduced, whereas the binding to erythroagglutinating phytohemagglutinin was increased, indicating that the level of beta 1-6 structure was decreased due to competition for substrate between intrinsic GnT-V and ectopically expressed GnT-III. Lung metastasis after intravenous injection of the transfectants into syngeneic and nude mice was significantly suppressed, suggesting that the decrease in beta 1-6 structure suppressed metastasis via a mechanism independent of the murine system. These transfectants also displayed decreased invasiveness into Matrigel and inhibited cell attachment to collagen and laminin. Cell growth was not affected. Our results demonstrate a causative role for beta 1-6 branches in invasion and cell attachment in the extravasation stage of metastasis.

Agglutination↗

PubMed1995

Heat-shock cognate 70 messenger RNA expression in postmortem human hippocampus: regional differences and age-related changes.

In situ hybridization of postmortem human brain tissue showed that constitutive heat-shock cognate 70 (hsc 70) mRNA was expressed in more than 50% of the pyramidal neurons in the hippocampal subfields. The ratio (%) of the hsc 70 mRNA-expressing neurons to the total neurons was significantly greater in CA3 and the hilus than in CA1 and CA2. The lower ratio in CA1 may be related to its vulnerability to various stresses. The ratio of hsc 70 mRNA-expressing neurons in CA1 was significantly greater in the older subjects than in the younger ones. This may reflect the up-regulated hsc 70 mRNA induction in response to a reduction in free hsc 70 because the binding of hsc 70 to aberrant proteins may be increased in aged persons.

Adult↗

PubMed1995

Differential mechanism of peptide YY and neuropeptide Y in inhibiting motility of guinea-pig colon.

The effect of peptide YY on contractility, acetylcholine release and noradrenaline release was examined in the isolated guinea-pig colon, and findings were compared with those for neuropeptide Y. Peptide YY and neuropeptide Y inhibited the twitch contractions mediated by the stimulation of cholinergic neurons. Peptide YY, neuropeptide Y, [Leu31,Pro34]neuropeptide Y and neuropeptide Y-(13-36) inhibited the electrically stimulated release of acetylcholine. Neuropeptide Y, but not peptide YY, inhibited the high K(+)-stimulated tetrodotoxin-resistant release of acetylcholine, while the inhibitory effect of neuropeptide Y disappeared after treatment with yohimbine. Neuropeptide Y, but not peptide YY or neuropeptide Y analogues, evoked the release of noradrenaline. After desensitization to the effects of neuropeptide Y, peptide YY inhibited electrically stimulated acetylcholine release. Thus, peptide YY inhibits acetylcholine release through stimulation of a receptor, distinct from the site of action of neuropeptide Y, located on cholinergic neurons as well as the neuropeptide Y Y1 and Y2 receptors in the guinea-pig colon. Neuropeptide Y inhibits acetylcholine release due to the noradrenaline release mediated by stimulation of a receptor distinct from neuropeptide Y Y1 and Y2 receptors, located on adrenergic neurons.

Acetylcholine↗

PubMed1995

Cell spreading in Colo 201 by staurosporin is alpha 3 beta 1 integrin-mediated with tyrosine phosphorylation of Src and tensin.

Staurosporin, a broad-spectrum kinase inhibitor, induced cell spreading in a human colon cancer cell line, Colo 201. On collagen and laminin, cell spreading was induced in more than 90% of the cells and was dependent on very late activation antigen-3, as shown by an antibody inhibition assay. Cell spreading required divalent cations and showed the order of preference Mn2+ > Mg2+ > Ca2+. On fibronectin, only about 30% of the cells were observed to spread, and spreading occurred via a non-integrin, RGD-independent pathway. Staurosporin-induced spreading was inhibited by treatment with tyrosine kinase inhibitors herbimycin A and methyl 2,5-dihydroxycinnamate. Despite the presence of staurosporin, seven proteins (220, 175, 150, 98, 62, 58, and 45 kDa) showed increased levels of tyrosine phosphorylation in association with cell adhesion. Two of these (58 and 220 kDa) were identified by immunoprecipitation as Src product and tensin, respectively. Flow cytometric analysis showed that the Colo 201 cells expressed the alpha 2, alpha 3, alpha 6, and beta 1 chains of integrin, but expression of these chains was not influenced by staurosporin. Immunofluorescence microscopy revealed that the alpha 3 chain, diffusely expressed on the cell surface in the absence of staurosporin, was concentrated at focal adhesion plaques after staurosporin treatment. Neither alpha 2 nor alpha 6 was focalized by the treatment.

Alkaloids↗

PubMed1995

Changes of beta-1,4-N-acetylglucosaminyltransferase III (GnT-III) in patients with leukaemia.

Changes in the activity and transcription of UDP-N-acetylglucosamine: beta-D-mannoside beta-1,4-N-acetylglucosaminyl-transferase III (GnT-III: EC 2.4.1.144) were investigated in haematological malignancies. GnT-III activity was elevated in patients with chronic myelogeneous leukaemia in blast crisis (CML-BC) and patients with multiple myeloma (MM); whereas most of the normal healthy subjects and patients with other haematological malignancies, including CML in its chronic phase, showed negligible activity. The GnT-III transcript of leukaemic cells from various haematological diseases showed a single band with a similar size. The ratio of GnT-III activity per normalized transcript in CML-BC was considerably higher than in the other conditions, which provided the possibility that in CML-BC the transcript or the enzyme protein might be more stable, or that a post-translational modification of the enzyme might enhance its activity. Furthermore, a lectin blot analysis of patient specimens and a lectin fluorescence study of CML cell lines revealed that E4-PHA binding to surface glycoproteins correlated with GnT-III activity, indicating that more bisecting GlcNAc was added to these glycoproteins, catalysed by elevated GnT-III in CML-BC.

Blast Crisis↗

PubMed1995

Effect of the transmembrane gradient of magnesium and sodium on the regulation of cytosolic free magnesium concentration in human platelets.

1. To clarify the mechanism by which cytosolic free Mg2+ concentrations ([Mg2+]i) are regulated in human platelets, we investigated platelet membrane permeability to Mg2+ by altering extracellular Mg2+ concentrations, and tested the existence of a Na(+)-Mg2+ exchanger by manipulating the transmembrane Na+ gradient. 2. Platelet [Mg2+]i was 421 +/- 52 mumol/l in healthy men. [Mg2+]i remained constant during a 120 min exposure to nominally zero (low) or 5 mmol/l (high) external Mg2+ concentrations. 3. Preincubation of platelets with 10(-4) mol/l ouabain effectively decreased the transmembrane Na+ gradient. The ouabain-induced increase in [Mg2+]i was statistically significant after 30 min of exposure (14.6 +/- 2.0%) and reached 24.6 +/- 4.5% after 60 min. Similarly, the replacement of extracellular Na+ with N-methyl-D-glucamine significantly increased [Mg2+]i by 48.5 +/- 3.9% and 78.8 +/- 12.5%, respectively. 4. These results suggest that [Mg2+]i is well controlled in the presence of large transmembrane Mg2+ concentration gradients, and a Na(+)-Mg2+ exchanger may be involved in the regulation of [Mg2+]i in human platelets.

Blood Platelets↗

PubMed1995

Augmented endogenous nitric oxide production in partial portal vein-ligated rats.

1. Endothelium-derived nitric oxide (NO) is a potent vasodilator. Because the body oxidizes it to nitrate ions, NO3-, measurement of the serum concentration and the urinary excretion of NO3- may be an index for endogenous NO. We investigated the role of NO on hyperdynamic circulation in cirrhotic and partial portal vein-ligated rats by measuring NO3. 2. Liver cirrhosis was induced by administration of thioacetamide. Systemic and splanchnic haemodynamics and splenic-systemic shunting were determined by tracer microspheres. The concentration of NO3- was measured by using high-performance liquid chromatography with an anioncolumn. 3. We found that systemic and splanchnic hyperdynamic circulation existed to almost the same extent in cirrhotic and in portal vein-ligated rats as compared to the controls and shamoperated rats, respectively. Splenic-systemic shunting was markedly greater in portal vein-ligated rats than in cirrhotic rats. 4. Serum NO3- levels and urinary excretion of NO3- in cirrhotic rats tended to increase as compared to the controls. On the other hand, the levels in portal vein-ligated rats were significantly increased as compared to those of the shamoperated rats, and were significantly and negatively correlated to the splanchnic arterial resistance and total vascular resistance. The amount of urinary excretion of NO3- significantly correlated to splenic-systemic shunting (r = 0.61, P < 0.05) only in portal vein-ligated rats. 5. We suggest that these high levels of NO3- in portal vein-ligated rats relate to the extensive formation of porto-collateral vasculature or acute changes in systemic and splanchnic haemodynamics due to portal vein-ligation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Intravenous administration of L-arginine inhibits angiotensin-converting enzyme in humans.

The iv administration of L-arginine, a precursor of endothelium-derived relaxing factor/nitric oxide, is known to decrease blood pressure in humans by its direct vasodilatory effects. The purpose of the present study was to determine whether L-arginine infusion modifies the renin-angiotensin (Ang)-aldosterone system as well as blood pressure and renal hemodynamics. L-Arginine and saline vehicle were iv administered to 10 healthy male subjects in random order on different days. L-Arginine infusion (500 mg/kg over 30 min) decreased mean blood pressure (from 81.2 +/- 2.7 to 74.0 +/- 2.5 mm Hg; P < 0.001) and renal vascular resistance (from 0.085 +/- 0.007 to 0.074 +/- 0.006 mm Hg/mL.min; P < 0.01) and increased heart rate (from 60.3 +/- 2.7 to 69.7 +/- 2.1 beats/min; P < 0.001) and renal plasma flow (from 616.6 +/- 37.8 to 701.0 +/- 49.2 mL/min; P < 0.05). L-Arginine reduced serum Ang-converting enzyme activity (from 10.4 +/- 0.6 to 8.9 +/- 0.5 nmol/mL.min; P < 0.05) and plasma Ang-II (from 19.3 +/- 3.3 to 12.7 +/- 2.8 pg/mL; P < 0.001), but had no effect on PRA or the glomerular filtration rate. The saline vehicle did not alter any of these parameters. The iv administration of L-arginine (endothelium-derived relaxing factor/nitric oxide) may reduce the plasma Ang-II concentration by inhibiting Ang-converting enzyme. The mechanism by which L-arginine infusion decreases blood pressure can be at least in part explained by inhibition of the renin-Ang system.

Adult↗

PubMed1995

Effect of 5,6,7,8-tetrahydroneopterin on the bovine endothelial cell injury induced by cumene hydroperoxide.

Neopterin is an 2-amino-4-hydroxypteridine derivative and a precursor of biopterin, which is derived from guanosine triphosphate. Previously, we have reported that 5,6,7,8-tetrahydroneopterin (NPH4), a reduced form of neopterin, possesses an antioxidant activity in various systems. In this study, we investigated the activity in more detailed manner and discussed the possible applications of this antioxidant. Analysis by electron spin resonance spectrometry indicated that NPH4 scavenged superoxide anion radicals and hydroxyl radicals as well. Moreover, NPH4 protected the rat brain homogenate from autoxidation. Next, we examined the effect of NPH4 on the cell injury induced by cumene hydroperoxide (CHP) in cultured bovine artery endothelial cells. The activity of lactate dehydrogenase, a marker enzyme of cell injury, was elevated by CHP in a dose-dependent manner, and this elevation was dose-dependently suppressed by NPH4. The elevation of lipid peroxide content was also inhibited by NPH4 in the same fashion. These data suggest that NPH4 would be effective against various diseases whose pathogenesis is active oxygen-related.

Animals↗

PubMed1995

Systemic magnesium deficiency disclosed by magnesium loading test in patients with essential hypertension.

The present study was designed to determine whether magnesium (Mg) deficiency is present in patients with essential hypertension. We measured the retention of an intravenously administered Mg load (0.2 mmol/kg MgSO4 over 4 h), and serum and erythrocyte Mg concentrations in 17 inpatients with essential hypertension and in 15 normotensive controls. There was no significant difference between the two groups in erythrocyte Mg concentration (normotensives vs., hypertensives: 2.0 +/- 0.5 vs. 2.1 +/- 0.4 mmol/l cells), serum Mg concentration (normotensives vs. hypertensive: 2.1 +/- 0.2 vs. 2.1 +/- 0.2 mg/dl), or in urinary Mg excretion (normotensives vs. hypertensives: 65.8 +/- 25.5 vs. 73.7 +/- 26.7 mg/day). However, Mg retention was significantly higher in hypertensives than in normotensives (normotensives vs. hypertensives: 31.8 +/- 12.1 vs. 41.9 +/- 13.3%). These results suggest that a systemic Mg deficiency, which is undectectable by serum or erythrocyte Mg determination, may exist in patients with essential hypertension.

Adult↗

PubMed1995

[Renal arterial disease-induced tubulo-interstitial lesions].

Renal arterial disease-induced tubulo-interstitial lesions described in this chapter include benign arterio- and/or arteriolo-sclerotic and malignant nephrosclerosis, renal infarction and renal cortical necrosis. In these conditions renal glomeruli as well as tubules are always involved, and consequent loss of nephrons, or renal parenchyma results in interstitial fibrotic changes. The parenchymal lesions have a spectrum from slowly progressive atrophy and loss to necrosis of abrupt onset and disappearance of glomeruli and tubules. As for glomerular reactions to the ischemia, the intermediate type consisted of mesangial degeneration and epithelial cell proliferation described as "alterative glomerulitis" is noteworthy. Briefly, in renal arterial diseases, glomeruli are rather variably involved than tubules and loss of the parenchyma results in interstitial fibrosis.

Arteriosclerosis↗

PubMed1995

Estimation of age from image processing of soft X-ray findings in Japanese male thyroid cartilages.

A method was developed for estimating the age at death based on image processing of soft X-ray pictures of thyroid cartilage from Japanese males. Data for 501 individuals were used to derive equations for this determination. Prior to image processing, gross morphological findings were used for estimation. Soft X-ray pictures indicated ossification with age and one index for image processing was introduced. The exponential function was applied to age estimation.

Adult↗

PubMed1995

Estimation of age from soft X-ray findings of Japanese females thyroid cartilages.

A method for estimating the age at death using the image processing of soft X-ray pictures of the thyroid cartilages of Japanese females was examined. The soft X-ray pictures showed increasing ossification with age. One index for image processing was introduced. It is ossification rate (OSFR). Corresponding to this index, one age estimation equation was obtained. This age estimation equation showed accuracies of 60% or more for the age range of +/- 5 years and about 80% for the age range of +/- 8 years.

Adult↗

PubMed1995

Autopsy cases of giant heart during the past ten years in Osaka (1985-1994).

We collected data from 30 autopsied cases, in which the heart weight were 800 g or more (maximum 1,300 g), at the Osaka Medical Examiner's office, for past 10 years. Among these cases, the cause of death was cardiac failure in 17 cases (56.7%), followed by pulmonary diseases (3 cases, 10.0%), cerebral infarction (3 cases, 10.0%), and aortic rupture (2 cases, 6.6%). The mean weight of the giant hearts was 880 g (about 77% of the cases) and 4 cases (13%) had 1,000 g or more. The mean height of the giant heart victims was close to the standard level, and thus the mean level of the ratio of heart weight to height were about 2.5 times higher than the standard levels. The liver weights were also greater by 500-1,000 g than the standard levels.

Adult↗

PubMed1995

[Combination therapy of doxifluridine, pirarubicin and cisplatin for human gastric cancers implanted in nude mice].

In the preclinical study of a new combination therapy for gastric cancer, dFTP, consisting of doxifluridine (5'-DFUR), pirarubicin (THP) and cisplatin (DDP) as a modification of conventional FAP regimen (5-fluorouracil+Adriamycin+DDP), we compared antitumor and toxic effects of two sequential treatment schedules, single injection of DDP before or after 4 daily administrations of 5'-DFUR, on 5 strains of human gastric cancer bearing nude mice. Results indicated that both schedules of the dFTP regimen had potent antitumor effects. There was no significant difference between them. On the other hand, in terms of the host toxicity as observed by body weight loss, the post-DDP schedule was significantly less toxic than pre-DDP. These results suggest that dFTP regimen (post-DDP schedule) may be useful for clinical treatment of gastric cancers.

Adenocarcinoma↗

PubMed1995

[Short somatosensory evoked potentials in patients with Fukuyama type congenital muscular dystrophy--a comparison with CT and MRI findings].

Seven patients with Fukuyama type congenital muscular dystrophy were studied. Low density areas (LDs) in the cerebral white matter on cranial CT were present in all 4 patients younger than 13 years of age and in 1 of 3 adult patients. LDs corresponded to low signals on T1 weighted MRI image and high signals on T2 weighted MRI image. The follow-up MRI showed a decreased tendency of the abnormal signals in 2 patients. Short somatosensory evoked potentials (SSEPs) in two infants, aged 4 months and 8 months, showed absent or depressed N1 amplitudes and delayed interpeak latencies from P3 to N1. N1 amplitudes increased on follow-up studies. SSEPs of five patients, who were older than 2 years of age, showed normal N1-P3 latencies. Amplitude of N1 was low in 2 patients with LD. Since the absent or depressed amplitude and delayed latency of N1 improved with the decrease of abnormal signals on MRI, we considered that N1 abnormalities show delayed myelination.

Adolescent↗

PubMed1995

[Postoperative interstitial pneumonia in primary lung cancer patients--its causes and management].

Eight patients who developed interstitial pneumonia after surgery for primary lung cancer were reviewed to investigate its causes and the key points in treatment. These patients accounted for 1.8% of 633 operated lung cancer patients at our institution over the last 9 years. Risk factors such as bilateral recurrent laryngeal nerve palsy, preoperative chemoradiotherapy, and extensive mediastinal involvement were present in all of them. Pneumonia developed on the nonoperated side in all patients between the 2nd and 45th postoperative day (mean: 18 days). In most of the patients, faint reticular shadows initially appeared in the lower lobe of the nonoperated lung, rapidly spread to the upper lobe, and finally affected the whole lung. Among these eight patients, the initial five patients died because steroids were only administered after the pneumonia had become widespread, whereas the last three patients received early steroid therapy and were saved. The findings that 1) this pneumonia originated from the lower lobe of the nonoperated lung where blood flow is highest postoperatively, 2) the eosinophil count increased just before the onset of pneumonia, and 3) early steroid therapy and immunosuppressive therapy were effective suggest that an allergic or autoimmune mechanism may play some role in its development. When characteristic reticular shadows appear in the lower lobe on the nonoperated side in a lung cancer patient, even if not associated with any symptoms, an early diagnosis of interstitial pneumonia and initiation of steroid therapy is mandatory to ensure survival.

Aged↗

PubMed1995

[Suppression of lung metastasis of B16 mouse melanoma cells by introduction of N-acetylglucosaminyltransferase III gene].

The beta 1-6 structure of N-oligosaccharides, formed by beta 1-6 N-acetylglucosaminyltransferase (GnT-V), is associated with metastatic potential. We established a highly metastatic subclone, B16-hm, from low metastatic B16-F1 murine melanoma cells. Introduction of the gene for beta 1-4 N-acetylglucosaminyltransferase (GnT-III) into B16-hm murine melanoma cells reduced the level of beta 1-6 structure by competing for the substrate, resulting in the suppression of lung metastasis in both syngeneic and nude mice, decreased invasiveness into the matrigel, and inhibition of cell attachment to collagen and laminin without affecting cell growth. The gene transfection altered the N-oligosaccharides of membrane glycoproteins, as measured by L-PHA and E-PHA binding. Our results demonstrated a causative role for beta 1-6 branches in the metastasis by gene transfection.

Animals↗