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Biomedical subjects

Y Masuda

Publications and source records attributed to Y Masuda.

At least 361 records · Page 20Linked to original sources
PubMed1995

Cloning and sequencing of a human endothelin converting enzyme in renal adenocarcinoma (ACHN) cells producing endothelin-2.

Endothelin (ET)-2 is a 21 residue vasoactive peptide which is biosynthesized from big ET-2(1-38) by a specific cleavage at Trp21-Val22 with an ET converting enzyme (ECE). To identify an ECE in ACHN (human renal adenocarcinoma) cells which produce ET-2, we have cloned and sequenced a novel cDNA encoding a human ECE in ACHN (hAECE). It encodes a 770 amino acid protein with a zinc-binding motif and a single membrane spanning region. The sequences of nucleic acids and amino acids from Leu45 to Trp770 of hAECE are identical to those from Leu33 to Trp758 of a human ECE in HUVEC (hHECE). The sequences in the amino-terminal moiety are divergent between hAECE and hHECE. Based on the difference of the amino-terminal amino acid sequences, ECEs reported so far, can be classified into two isoforms. These results strongly suggest that an alternative splicing might occur in the 5'-terminal region of the ECE pre-mRNA.

Adenocarcinoma↗
PubMed1995

AF64A disrupts retrieval processes in long-term memory of mice.

Intracerebroventricular (i.c.v.) injection of ethylcholine mustard aziridinium ion (AF64A) in mice caused a reversible impairment of retrieval processing in long-term memory. After long retention intervals (1-3 weeks), AF64A-treated mice demonstrated marked impairment of behavioural performance previously acquired in a complex multiple maze task. This behavioural deficit was dose dependently ameliorated by the administration of oxotremorine. In parallel with the behavioural deficit, AF64A selectively decreased acetylcholine (ACh) levels in the hippocampus. These findings suggest that the reversible behavioural deficit induced by AF64A should be regarded as a retrieval failure in long-term memory, and not as a retention failure. This failure was largely associated with dysfunction of the cholinergic neuronal system in the hippocampus.

Animals↗
PubMed1995

In vivo evidence for non-universal usage of the codon CUG in Candida maltosa.

An alkane-assimilating yeast Candida maltosa had been studied in order to establish systems suitable for biotransformation of hydrophobic compounds. However, functional expression of heterologous genes tested for this purpose had not been successful in several cases. On the other hand, it had been reported that the codon CUG, a universal leucine codon, is read as serine in C. cylindracea. The same altered codon usage had also been suggested by in vitro experiments in some Candida yeasts which are phylogenetically closely related to C. maltosa. In this study we have shown that the failure in functional expression of a heterologous gene is due to the fact that the codon CUG is read as serine in C. maltosa. This conclusion was drawn from the following experimental results: (1) when a cytochrome P450 gene of C. maltosa containing a CTG codon was expressed in C. maltosa, the corresponding amino acid was found to be serine, and not leucine; (2) a tRNA gene with an almost identical structure to that of the tRNASerCAG gene of C. albicans could be isolated from the genome of C. maltosa; (3) the Saccharomyces cerevisiae URA3 gene, which has one CTG codon, could not complement the ura3 mutation of C. maltosa as itself, but when the CTG codon was changed to another leucine codon, CTC, the mutated gene could complement the ura3 mutation. The last result is the first example of succeeding in functional expression of a heterologous gene in Candida species having an altered codon usage by changing the CTG codon in the gene to another codon.

Amino Acid Sequence↗
PubMed1995

Suppression of in vivo tumor growth by the transfection of the interleukin-5 gene into colon tumor cells.

To investigate the influence of tumor producing interleukin-5 (IL-5) on growth kinetics of tumors, we transduced the murine IL-5 gene into murine colon C26 tumor cells. Two IL-5-secreting clones, low-level IL-5 producer C26-8B and high-level IL-5 producer C26-6F, were established. Both tumors, C26-6F and C26-8B, grew more slowly than the mock C26 tumor, although the in vitro growth rate of these IL-5 transfectants was much the same as that of the mock C26 cells. There was a significantly decreased number of colonies in the lung of mice given C26-6F or C26-8B tumors i.v. than in mice given mock C26 tumors i.v. Moreover, in mice given C26-6F cells i.v., a smaller number of tumor colonies in the lung was observed, as compared to the case with C26-6B cells. While the growth rate of C26-8B tumors in mice treated with anti-IL-5 mAb was more rapid than that seen in control mAb-treated mice, growth of C26-6F tumors in anti-IL-5-mAb-treated mice was slightly more rapid compared to findings in control mAb-treated mice. The isotype-matched mAb did not alter the in vitro growth of mock-C26 cells or of the IL-5-gene-modified C26 cells. Growth of IL-5-secreting C26 tumors transplanted in nude mice was also inhibited. These results suggest that tumor-producing IL-5 inhibits growth of colon tumors mediated through T-cell-independent protective mechanisms of the host.

Animals↗
PubMed1995

Pancreatic enlargement in obstructive jaundice. Effects of biliary stream diversion in humans.

To verify the influence of obstructive jaundice on pancreatic growth, the anteroposterior width of the pancreas was measured by computed tomography in 30 cholangiocarcinoma patients excluded patients with distal bile duct tumor (jaundice group) and 74 control subjects. Follow-up examinations were performed on 12 patients with and without internal biliary drainage to elucidate the temporal relationship between pancreatic enlargement and the diversion of the obstructed biliary stream. Histologic analysis on autopsy samples from 13 control and 10 jaundice cases also was performed. Mean pancreatic head and body widths in the jaundice group were 2.93 +/- 0.3 cm and 2.01 +/- 0.3 cm, respectively. These values were significantly greater than those of the controls (2.13 +/- 0.3 cm and 1.49 +/- 0.3 cm, P < 0.01). The glandular widths returned to their normal sizes following internal biliary drainage. No changes were seen in patients who underwent external drainage alone. Histologic examination revealed that enlargement of the acinar cells or of the islet of Langerhans was often seen in the jaundiced patients. Therefore obstructive jaundice is thought to cause pancreatic growth through a trophic effect by interrupting biliary circulation.

Aged↗
PubMed1995

Gravitropic response in Eichhornia cressipes (Water Hyacinth) 1. Process of gravitropic bending in the peduncle.

In the last half of the anthokinetic cycle in Eichhornia cressipes the peduncle showed a two-step bending response which started after the completion of the flowering: the primary bending in the upper region and the second one in the base of the peduncle. In the present study, only the primary bending response was examined and the following results were obtained. (1) Under the condition in the Western Japan, the anthokinetic cycle completed in 36-40 hr. The inflorescence started to grow during night, reaching the full flowering stage next morning, and the bending was initiated in the evening and completed next morning. (2) The bending was a positive gravitropism since the peduncle did not show bending when it was placed on a horizontal clinostat rotating at 2-3 rpm, or when the plant was placed up-side-down. (3) Before the end of flowering phase, the peduncle showed a normal negative gravitropic response but afterward it acquired the property to show a positive gravitropic response. (4) The bending was due to the extension of convex side of the peduncle, accompanied by a shrinkage of the concave side. The extension of the upper side was caused by cell extension. At the turning point from negative to positive gravitropic response, the extension of the peduncle ceased for several hours. From the above results it is concluded that the primary bending response of the peduncle in water hyacinth was a positive gravitropism.

Biomechanical Phenomena↗
PubMed1995

Abnormalities in elastic fibers and other connective-tissue components of floppy mitral valve.

Histologic, immunohistochemical, and ultrastructural studies were performed on 12 floppy mitral valves, 4 mitral valves showing focal myxomatous changes without prolapse, and 3 normal mitral valves. All floppy mitral valves were thickened by deposits of proteoglycans and also showed diverse structural abnormalities in collagen and elastic fibers. From these observations we conclude that (1) the structure of all major components of connective tissue in floppy mitral valves is abnormal; (2) alterations in collagen and accumulations of proteoglycans are nonspecific changes that may be caused by the abnormal mechanical forces to which floppy mitral valves are subjected because of their excessively large surface area; (3) the presence of excessive amounts of proteoglycans may interfere with the normal assembly of collagen and elastic fibers; (4) abnormalities of elastic fibers resemble those in other conditions characterized by structural dilatation or tissue expansion; and (5) alterations in elastin could result from defective formation, increased degradation, or both.

Actin Cytoskeleton↗
PubMed1995

Basal levels of noradrenaline, dopamine, 5-hydroxytryptamine, and acetylcholine in the submandibular, parotid, and sublingual glands of mice and rats.

The salivary glands of 5-week-old mice and rats were divided into submandibular, parotid, and sublingual and analysed to determine basal levels of the neurotransmitters noradrenaline (NE) and acetylcholine (ACh) and the possible neurotransmitters dopamine (DA) and 5-hydroxytryptamine (5-HT), using a combination of high-performance liquid chromatography coupled with coulometric and amperometric detection and a direct injection technique employing crude homogenate supernatants. In both species, levels of NE were higher in the submandibular than in the other salivary glands, whereas levels of ACh were higher in the mouse submandibular and the rat sublingual glands than in other glands. In all the salivary glands, levels of DA were markedly lower than those of other target substances. Levels of 5-HT were similar in all salivary glands. These results show that in mouse and rat salivary glands, species differences in neurotransmitter distribution are relatively small, whereas there are considerable differences in distribution between the salivary glands.

Acetylcholine↗
PubMed1995

The dopaminergic system modulates the endogenous opioid system in guinea-pig isolated ileal longitudinal muscle.

The effects of the dopamine antagonists haloperidol and sultopride were investigated on the twitch response, evoked by 0.1 Hz stimulation of guinea-pig isolated ileal longitudinal muscle, and on the inhibition of the twitch response induced by 10 Hz stimulation (post-tetanic twitch inhibition) and by application of opioids. Both haloperidol and sultopride concentration-dependently inhibited the twitch response, with threshold concentrations of 2 and 50 microM, respectively, and could also shift the concentration-response curve for ACh-contraction to the right in a non-competitive manner. Haloperidol (1 microM) and sultopride (20 microM) increased post-tetanic twitch inhibition and this could be prevented by naloxone (100 nM). Twitch inhibition induced by morphine and dynorphin 1-13 was not affected by haloperidol (1 microM) or sultopride (20 microM). Prazosin (1 microM) and yohimbine (2 microM) did not affect either the twitch response or the post-tetanic twitch inhibition. These results suggest that dopamine receptors are involved in the modulation of the ileal opioid system, in such a manner as to diminish the release of endogenous opioids by tetanic stimulation.

Amisulpride↗
PubMed1995

Effects of polychlorinated dibenzo-p-dioxin and dibenzofuran congeners in human lymphoblastoid cells on aryl hydrocarbon hydroxylase activity.

The separate and concurrent effects of polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners on aryl hydrocarbon hydroxylase (AHH) activity in human lymphoblastoid cells were examined. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (2,3,7,8-tetraCDD) induced AHH activity about 9-fold acetone-treated AHH activity, while octachlorodibenzo-p-dioxin (octaCDD) did not affect the AHH activity and 2,4,6,8-tetrachlorodibenzofuran (2,4,6,8-tetraCDF) reduced the AHH activity by 34%. The concurrent effect of 2,3,7,8-tetraCDD with 1,3,6,8-tetraCDD on AHH inducibility was much smaller than expected. The concurrent effect of 2,3,7,8-tetraCDD with 2,4,6,8-tetraCDF, octaCDD or 3,3',4,4',5,5'-hexaCB was as much as the effect of 2,3,7,8-tetraCDD alone. There was a difference between 3-methylcholanthrene (MC) and 2,3,7,8-tetraCDD in the concurrent effects of 3-methylsulfone-3',4,4',5-tetraCB (3-MSF-3',4,4',5-tetraCB) on AHH activity. The concurrent effect of MC with 3-MSF-3',4,4',5-tetraCB on AHH activity was equal to the effect of MC alone while that of 2,3,7,8-tetraCDD and 3-MSF-3',4,4',5-tetraCB on AHH activity was inhibitory. These results imply that congeners of PCDD and PCDF are considered to be more or less effective and isozymes of cytochrome P450, key enzymes for the AHH, induced by them are differently inhibited.

Aryl Hydrocarbon Hydroxylases↗
PubMed1995

Bufalin induces apoptosis and influences the expression of apoptosis-related genes in human leukemia cells.

A low concentration of bufalin, a component of bufadienoides in the traditional Chinese medicine chan'su, was shown previously to induce differentiation of a broad range of human leukemia cell lines. In the present study, we found that bufalin at concentrations of 10(-7) M and higher induced apoptosis in human leukemia cells, such as HL60, ML1, but not in mouse leukemia M1 cells. A mere 15 min pretreatment of HL60 cells with 10(-6) M bufalin, followed by incubation for 15 h without bufalin, caused fragmentation of DNA and a decrease in cell viability, indicating that the signal for induction of apoptosis is triggered rapidly upon treatment with bufalin. Bufalin-induced apoptosis in HL60 cells was inhibited by ZnCl2, an inhibitor of endonuclease, but not by cycloheximide, an inhibitor of protein synthesis. Northern blot analysis revealed that the levels of expression of the c-myc and bcl-2 genes in HL60 cells decreased with time after treatment with bufalin. These results suggest that bufalin induces apoptosis specifically in human leukemia cells by altering the expression of these genes involved in apoptosis.

Animals↗
PubMed1995

Cardiovascular selectivity of 1,4-dihydropyridine derivatives, efonidipine (NZ-105), nicardipine and structure related compounds in isolated guinea-pig tissues.

1. The cardiovascular selectivities of 1,4-dihydropyridine derivatives, efonidipine (NZ-105), nicardipine, 3NZ5NIC (the drug with NZ-105-type side-chain at C3 position and nicardipine-type at C5) and 3NIC5NZ (the drug with nicardipine-type side chain at C3 and NZ-105-type at C5) were studied in vitro. 2. All four compounds caused relaxation of guinea-pig aortae precontracted with a high K+. The pEC50 values were 7.5, 8.3, 8.1 and 5.6, for NZ-105, nicardipine, 3NIC5NZ and 3NZ5NIC, respectively. The relaxation produced by NZ-105 was slower in onset than those produced by the other compounds. The rate constant K(hr-1) of the relaxations were 0.59, 1.31, 1.02 and 1.24, for NZ-105, nicardipine, 3NIC5NZ and 3NZ5NIC, respectively. 3. In the electrically paced guinea-pig papillary muscles, NZ-105, 3NIC5NZ and 3NZ5NIC, even at concentrations as high as 10(-6) M, slightly decreased the contractile force (by 44.9 +/- 7.1%, 58.6 +/- 5.4% and 52.2 +/- 3.9%, respectively), whereas 10(-6) M nicardipine decreased the force by 84.9 +/- 3.3%. The negative inotropic effect of NZ-105 and 3NIC5NZ, but not that of 3NZ5NIC or nicardipine, was over 10 times weaker than their vasorelaxant effect. 4. In the guinea-pig right atria, NZ-105 and nicardipine at 10(-8) M decreased the spontaneous contraction rate by 67.9 +/- 15.0% and 39.7 +/- 15.4%, respectively. 3NIC5NZ at 3 x 10(-9) M and 3NZ5NIC at 3 x 10(-8) M had little effect on the rate, whereas 10(-8) M 3NIC5NZ and 10(-7) M 3NZ5NIC arrested the beating within 3 hr after administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Effects of efonidipine hydrochloride (NZ-105), a calcium antagonist, on renal function in conscious spontaneously hypertensive rats.

1. We investigated the effects of short- and long-term administration of efonidipine hydrochloride (NZ-105), 1,4-dihydropyridine derivative, in conscious spontaneously hypertensive rats (SHR). 2. Oral administration of NZ-105 for 12 weeks caused diuretic and natriuretic effects, which were not attenuated during the experimental period. 3. In the short-term experiment for investigating the mechanism of the diuretic effect, intravenous injection of NZ-105 (0.03 mg/kg of body weight) significantly increased the urine volume (UV), renal plasma flow (RPF) and glomerular filtration rate (GFR). The increment rate of UV and RPF was 105.4 +/- 17.8% and 111.7 +/- 72.8%, respectively, which were larger than the increment rate of GFR (38.5 +/- 14.0%). 4. The diuretic or natriuretic effect of NZ-105 was suggested to be due to both the inhibition of sodium reabsorption and, at least in part, the increase of GFR.

Animals↗
PubMed1995

Direct evidence for the occurrence of superoxide radicals in the small intestine of the burned rat.

To determine if superoxide radicals (O2-) and related metabolites are generated in extradermal tissues of burned animals, 2-methyl-6-[p-methoxyphenyl]-3,7-dihydroimidazol [1,2-å]pyrazin-3-one (MCLA) was infused intravenously into rats, and change in the chemiluminescence (CL) intensity of the small intestine was determined by using a sensitive photodetector. When animals were challenged with burn stress of 40% total body surface area (TBSA), the CL intensity of the intestine gradually increased, reaching a maximum within 1 hour and remaining elevated for up to 3 hours. Pretreatment of animals with a long-acting superoxide dismutase (SOD) derivative (SM-SOD) significantly inhibited the increase in CL intensity. Administration of SM-SOD immediately after inducing burn injury also significantly inhibited the increase in CL. These results suggest that superoxide radicals are generated in extradermal tissues, such as the small intestine, in the early stage after burn injury.

Animals↗
PubMed1995

Demonstration of Epstein-Barr virus genomes, using polymerase chain reaction in situ hybridization in paraffin-embedded lymphoid tissues.

We used the polymerase chain reaction (PCR) in situ hybridization (ISH) (PCR-ISH) on sections of malignant lymphoma and nonspecific lymphadenitis to detect small amounts of Epstein-Barr virus (EBV), a DNA virus of the herpes virus family. We first surveyed the EBV DNA by Southern blot analysis and PCR, and then compared results of the two PCR/ISH methodologies with the results of simplified/sensitive ISH for the positive cases. The target of the simplified in situ (DNA-ISH) was a few copies of EBV DNA per cell, and the target of the sensitive in situ (RNA-ISH) was as many as 10(7) copies of EBV RNA per cell. When EBV DNA was detected by Southern blot, DNA-ISH, RNA-ISH and PCR-ISH all revealed EBV genomes. When PCR revealed only amplified EBV DNA, DNA-ISH showed no EBV genomes, but PCR-ISH and RNA-ISH showed EBV genomes in a few cells. When PCR showed no detectable amplified EBV DNA, all of DNA-ISH, RNA-ISH and PCR-ISH showed no genomes. These findings indicate that PCR-ISH consistently detected a few copies of the EBV virions. The PCR-ISH was as sensitive as RNA-ISH. The RNA-ISH could not detect virus if RNA was not expressed, but the PCR-ISH could detect virus without such expression. The ability to detect a single copy of a specific gene in situ has many advantages and multiple applications in molecular biology, pathology, and cell biology.

Base Sequence↗
PubMed1995

Superficial siderosis of the central nervous system: a case with an unruptured intracranial aneurysm.

We present a case of superficial siderosis (SS) of the central nervous system (CNS) with an unruptured intracranial aneurysm to illustrate that the commonly encountered unexplainable progressive sensorineural hearing loss (SNHL) can be an important sign for the early awareness of this rare disorder. The literature on SS is reviewed and the pathogenesis of SS is discussed.

Central Nervous System Diseases↗
PubMed1995

Apoptosis in the repair process of experimental proliferative glomerulonephritis.

The recovery from the proliferative glomerulonephritis (GN) with reduction of hypercellularity is known in various experimental and human GN. To elucidate the participation of apoptosis in GN, we studied the experimental Thy-1.1 GN for six weeks. Apoptosis was recognized by both light and electron microscopy, and the biochemical expression of apoptosis was morphologically confirmed by in situ end-labeling method of fragmented DNA, using terminal deoxy-transferase. Mesangioproliferative GN was induced by a single administration of anti-Thy-1.1 monoclonal antibody in a rat. Mesangial cell proliferation started early in the process and the number of glomerular cells peaked from day 7 to day 10. Subsequently, the degree of proliferative lesion diminished with obvious reconstruction of the capillary structure, as well as decrease in the number of glomerular cells. During this period, proliferated mesangial cells returned to their original level of cellularity and apoptosis apparently increased in number among the glomeruli. Apoptosis was significantly noted from day 7 to week 4 and was in its maximum at day 10 to week 2. Following this period, by week 6 most of the glomeruli reverted to their original structure. The number of infiltrated neutrophils and macrophages in the glomeruli slowly decreased during the course of the disease, and a few apoptosis were also observed. It is concluded that proliferated glomerular cells regress by apoptosis in the repairing process of GN. Apoptosis plays an essential role in the recovery to the original glomerular structure in GN.

Animals↗