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Biomedical subjects

M Yuasa

Publications and source records attributed to M Yuasa.

At least 19 recordsLinked to original sources
PubMed2005

The entrapment of kojic oleate in bilayer vesicles.

The entrapment of kojic acid and its newly synthesized ester (kojic oleate) has been evaluated. Kojic oleate was synthesized by DCC (N,N'-dicyclohexylcarbodiimide, DCC)/(4-(N,N-dimethylamino)pyridine, DMAP) esterification method and identified by FAB-MS and 1H NMR. The synthesized product was mainly 7-O-kojic oleate with more than 80% yield. It was entrapped in vesicular membrane prepared from 9.5:9.5:1.0 molar ratio of amphiphiles (Span 60, Tween 61 or DPPC), cholesterol and dicetyl phosphate. Kojic acid was encapsulated in the water compartment of these vesicles in order to confirm the vesicle formation. The morphology and particle size of the vesicles were characterized by an optical microscope and transmission electron microscope (TEM). The entrapment efficiencies of kojic acid and kojic oleate in the vesicles were investigated by dialysis and column chromatography, respectively. The contents of the entrapped kojic acid and kojic oleate were assayed by HPLC. The entrapment efficiency of kojic acid was 0.01-0.04 mol, whereas kojic oleate gave higher entrapment efficiency of 0.25-0.35 mol/mol of the total compositions of amphiphile/cholesterol/dicetyl phosphate. Structural modification of kojic acid improved its entrapment in the vesicles. Tween 61 vesicles could entrap kojic oleate more than did Span 60 vesicles. The pi-A isotherms revealed the lower area per molecule of Span 60, which formed a more rigid pack of its molecule on air/water interface than that of Tween 61. This implied the high rigidity of vesicular membrane prepared with Span 60 led to the lower amount of kojic oleate entrapped in the vesicles. From the release study of kojic acid through the dialysis membrane, it indicated that the intercalation of kojic oleate in the vesicular membranes did not significantly affect the release of kojic acid from the vesicles.

Androstanes↗
PubMed2001

Biochemical analysis of replication factor C from the hyperthermophilic archaeon Pyrococcus furiosus.

Replication factor C (RFC) and proliferating cell nuclear antigen (PCNA) are accessory proteins essential for processive DNA synthesis in the domain Eucarya. The function of RFC is to load PCNA, a processivity factor of eukaryotic DNA polymerases delta and epsilon, onto primed DNA templates. RFC-like genes, arranged in tandem in the Pyrococcus furiosus genome, were cloned and expressed individually in Escherichia coli cells to determine their roles in DNA synthesis. The P. furiosus RFC (PfuRFC) consists of a small subunit (RFCS) and a large subunit (RFCL). Highly purified RFCS possesses an ATPase activity, which was stimulated up to twofold in the presence of both single-stranded DNA (ssDNA) and P. furiosus PCNA (PfuPCNA). The ATPase activity of PfuRFC itself was as strong as that of RFCS. However, in the presence of PfuPCNA and ssDNA, PfuRFC exhibited a 10-fold increase in ATPase activity under the same conditions. RFCL formed very large complexes by itself and had an extremely weak ATPase activity, which was not stimulated by PfuPCNA and DNA. The PfuRFC stimulated PfuPCNA-dependent DNA synthesis by both polymerase I and polymerase II from P. furiosus. We propose that PfuRFC is required for efficient loading of PfuPCNA and that the role of RFC in processive DNA synthesis is conserved in Archaea and Eucarya.

Adenosine Triphosphatases↗
PubMed2001

[Similarity between primary health care and health promotion].

Primary Health Care is recognized as a core health strategy in developing countries, proclaimed by the Declaration at Alma-Ata, while for industrialized countries, Health Promotion was stated in the Ottawa Charter. The concept of Primary Health Care, having been influenced by the Social Development movement for basic human needs in the 70s, is almost entirely consistent with Health Promotion, which is in accord with the principles of Human Development pronounced in the late 80s through the 90s. Thus, Health Promotion could be developed as a health strategy also in developing countries while Primary Health Care could similarly be adopted as a health strategy in the industrialized world.

Developing Countries↗
PubMed2000

Genomic structure, chromosomal localization and identification of mutations in the xeroderma pigmentosum variant (XPV) gene.

The xeroderma pigmentosum variant (XP-V) is one of the most common forms of this cancer-prone syndrome. XP groups A through G are characterized by defective nucleotide excision repair, whereas the XP-V phenotype is proficient in this pathway. The XPV gene encodes DNA polymerase eta, which catalyzes an accurate translesion synthesis, indicating that the XPV gene contributes tumor suppression in normal individuals. Here we describe the genomic structure and chromosomal localization of the XPV gene, which includes 11 exons covering the entire coding sequence, lacks a TATA sequence in the upstream region of the transcription-initiation, and is located at the chromosome band 6p21.1-6p12. Analyses of patient-derived XP-V cell lines strongly suggested that three of four cell lines carried homozygous mutations in the XPV gene. The fourth cell line, XP1RO, carried heterozygous point mutations in the XPV gene, one of which was located at the splice acceptor site of exon 2, resulting in the omission of exon 2 from the mature mRNA. These findings provide a basis for diagnosis and therapy of XP-V patients.

Alleles↗
PubMed2000

Molecular dimensions of Hb-based O(2) carriers determine constriction of resistance arteries and hypertension.

The effect of molecular dimension of hemoglobin (Hb)-based O(2) carriers on the diameter of resistance arteries (A(0), 158 +/- 21 microm) and arterial blood pressure were studied in the conscious hamster dorsal skinfold model. Cross-linked Hb (XLHb), polyethylene glycol (PEG)-conjugated Hb, hydroxyethylstarch-conjugated XLHb, polymerized XLHb, and PEG-modified Hb vesicles (PEG-HbV) were synthesized. Their molecular diameters were 7, 22, 47, 68, and 224 nm, respectively. The bolus infusion of 7 ml/kg of XLHb (5 g/dl) caused an immediate hypertension (+34 +/- 13 mmHg at 3 h) with a simultaneous decrease in A(0) diameter (79 +/- 8% of basal value) and a blood flow decrease throughout the microvascular network. The diameter of smaller arterioles did not change significantly. Infusion of larger O(2) carriers resulted in lesser vasoconstriction and hypertension, with PEG-HbV showing the smallest changes. Constriction of resistance arteries was found to be correlated with the level of hypertension, and the responses were proportional to the molecular dimensions of the O(2) carriers. The underlying mechanism is not evident from these experiments; however, it is likely that the effects are related to the diffusion properties of the different Hb molecules.

Animals↗
PubMed1999

The XPV (xeroderma pigmentosum variant) gene encodes human DNA polymerase eta.

Xeroderma pigmentosum variant (XP-V) is an inherited disorder which is associated with increased incidence of sunlight-induced skin cancers. Unlike other xeroderma pigmentosum cells (belonging to groups XP-A to XP-G), XP-V cells carry out normal nucleotide-excision repair processes but are defective in their replication of ultraviolet-damaged DNA. It has been suspected for some time that the XPV gene encodes a protein that is involved in trans-lesion DNA synthesis, but the gene product has never been isolated. Using an improved cell-free assay for trans-lesion DNA synthesis, we have recently isolated a DNA polymerase from HeLa cells that continues replication on damaged DNA by bypassing ultraviolet-induced thymine dimers in XP-V cell extracts. Here we show that this polymerase is a human homologue of the yeast Rad30 protein, recently identified as DNA polymerase eta. This polymerase and yeast Rad30 are members of a family of damage-bypass replication proteins which comprises the Escherichia coli proteins UmuC and DinB and the yeast Rev1 protein. We found that all XP-V cells examined carry mutations in their DNA polymerase eta gene. Recombinant human DNA polymerase eta corrects the inability of XP-V cell extracts to carry out DNA replication by bypassing thymine dimers on damaged DNA. Together, these results indicate that DNA polymerase eta could be the XPV gene product.

Alleles↗
PubMed1999

A kuroko-type polymetallic sulfide deposit in a submarine silicic caldera

Manned submersible studies have delineated a large and actively growing Kuroko-type volcanogenic massive sulfide deposit 400 kilometers south of Tokyo in Myojin Knoll submarine caldera. The sulfide body is located on the caldera floor at a depth of 1210 to 1360 meters, has an area of 400 by 400 by 30 meters, and is notably rich in gold and silver. The discovery of a large Kuroko-type polymetallic sulfide deposit in this arc-front caldera raises the possibility that the numerous unexplored submarine silicic calderas elsewhere might have similar deposits.

Journal Article↗
PubMed1999

Activation of extracellular signal-regulated kinase in lung tissues of mice treated with carcinogen.

The activation of extracellular signal-regulated kinase (ERK) in lung tissues of mice, as determined by the appearance of phosphorylated form, was observed on day 30 after urethane injection, and the activation also occurred in urethane-induced lung tumors. Immunohistochemical analysis using anti-phosphorylated ERK antibody indicated that the active form of ERK localized in alveolar epithelial cells. Furthermore, we confirmed by immunoprecipitation and immunoblot analysis that other essential components of the ERK cascade, that is, Ras, Raf and MEK (known as ERK kinase) were activated. These results indicate that the activation of the ERK signal in alveolar epithelial cells at the early stage of urethane-induced lung carcinogenesis is an important factor to develop lung tumors.

Animals↗
PubMed1999

Iron depletion prevents adenine nucleotide decomposition and an increase of xanthine oxidase activity in the liver of the Long Evans Cinnamon (LEC) rat, an animal model of Wilson's disease.

The Long Evans Cinnamon (LEC) rat, which accumulates excess Cu in the liver as in patients with Wilson's disease, is a mutant strain displaying spontaneous hepatitis. It was reported that Fe, like Cu, increases in the liver and that the severity of hepatitis is modified by Fe in the diet. In this experiment, oxidative stress increased by Fe was investigated before the onset of hepatitis. To examine the effect of Fe on the progress into hepatitis, LEC female rats were fed an Fe-regular (Fe 214 microg/g; Fe(+) group) or an Fe-restricted (Fe 14 microg/g; Fe(-) group) diet from 53 days of age for 35 days. Fischer rats were also fed as control animals. Adenine nucleotide decomposition was determined as an index of oxidative stress based on xanthine oxidase activity. The size of the hepatic pool of adenine nucleotides (ATP+ADP+AMP) was significantly smaller in LEC rats than Fischer rats. The energy charge (ATP+0.5ADP)/(ATP+ADP+AMP) was smaller in Fe(+) groups than in Fe(-) groups. In the LEC rat liver, the Fe concentration in the Fe(+) group was 160% of that in Fe(-) group and the correlation coefficient between the hepatic Fe concentration and the energy charge was significant. In this strain, an increase of xanthine oxidase activity resulted in an increase of xanthine, an oxidized metabolite of hypoxanthine in the liver. The results suggest the involvement of the Fe in the progression into hepatitis in the LEC rat, even if the dietary Fe concentration is similar to that of commercial diet.

Adenine Nucleotides↗
PubMed1999

Automated synthesis of [11C]choline, a positron-emitting tracer for tumor imaging.

(beta-Hydroxyethyl)tri([11C]methyl)ammonium ([11C]choline) is a tracer very effective in imaging various human tumors using positron emission tomography (PET). We have constructed a computer-controlled [11C]choline synthetic apparatus which carries out the whole process of synthesis and product purification automatically. The setup is simple and the process quick. In 20 min, 11 GBq of [11C]choline (chloride) is obtainable from 26 GBq of [11C]CO2. The final product is a sterile and pyrogen-free [11C]choline "injection".

Carbon Radioisotopes↗
PubMed1999

Possible causes of diabetes mellitus in cattle infected with bovine viral diarrhoea virus.

In cattle, we encountered insulin-dependent diabetes mellitus (IDDM) associated with bovine viral diarrhoea virus (BVDV) infection. To estimate the correlation between IDDM and BVDV infection, the distribution of BVDV in the pancreas and islet-cell antibody (ICA) were investigated. The distribution of BVDV in the pancreas was examined by in situ hybridization using two oligonucleotide probes that recognized the gp25- and p14-coding regions of the BVDV gene. ICA was examined by indirect fluorescence antibody assay using the sera from affected cattle and pancreata from normal cattle. In the pancreata of all BVDV-infected cattle, including IDDM-complicated cattle, oligonucleotide probe hybridized portions were recognized. In short, BVDV genes were detected not only in IDDM-complicated cattle but also in uncomplicated cattle. Moreover, there was no hybridized portion in the islet cells. In BVDV-infected and IDDM-complicated cattle, ICA was frequently detected. On the other hand, ICA was not detected in BVDV-infected and IDDM uncomplicated cattle. These results suggest that IDDM associated with BVDV infection is not a direct effect of BVDV on islet cells. Therefore, as BVDV did not induce IDDM in any cases, it appears that BVDV does not induce IDDM directly, but rather may be an autoimmune disease induced by autoantibodies against islet cells.

Animals↗
PubMed1999

Synthesis and pharmacological activity of pyrazolopyrrolopyrimidine derivatives having vasorelaxing activity.

A new series of 5-substituted and 5-nonsubstituted pyrazolopyrrolopyrimidine derivatives were synthesized, and their vasorelaxing and hypotensive activities were evaluated. The syntheses were efficiently accomplished through the use of three key intermediates (7, 16, and 24), as shown in Schemes I-III. The desired pharmacological activities were confirmed on the basis of vasorelaxing activity in rat aorta (in vitro) and hypotensive activity in rats (in vivo). Specifically, compound 25 exhibited the strongest activity and appears to be a promising clinical lead for the development of a new antihypertensive agent.

Animals↗
PubMed1999

[Table-moving contrast-enhanced MR angiography of abdominal aortic aneurysm].

Table-moving contrast-enhanced MR angiography (MRA) was performed in 14 cases of abdominal aortic aneurysm to evaluate its clinical usefulness. In all cases, aneurysms were clearly demonstrated and image quality was clinically acceptable. Findings of reconstructed MRA were highly consistent with those of DSA, and thrombosed areas were confirmed on source images. Main aortic branches including renal arteries, common iliac arteries, and internal and external iliac arteries were readily identified on reconstructed MRA and/or source images. Additional findings such as thoracic aortic aneurysm (n = 1), common iliac aneurysm (n = 6), external iliac aneurysm (n = 1), internal iliac aneurysm (n = 1), femoral arterial obstruction (n = 2), and femoral arterial stenosis (n = 4) were also detected. Although table-moving MRA may have disadvantages like reduced blood signal and limited spatial resolution compared with the conventional contrast-enhanced technique, the images that were obtained provided sufficient contrast and resolution for preoperative evaluation. Because abdominal aortic aneurysm is accompanied by various arterial abnormalities in many of the large arteries, table-moving MRA was considered a suitable technique for comprehensive assessment.

Aged↗
PubMed1998

The repetitive activation of extracellular signal-regulated kinase is required for renal regeneration in rat.

In this study, we investigated the activation of p42 extracellular signal-regulated kinase (ERK2) during renal regeneration after HgCl2-induced acute renal failure (ARF) in rat. ERK2 activation was observed at 5 and 29 hr after HgCl2 injection, respectively. The tyrosine phosphorylation of hepatocyte growth factor receptor (c-MET) occurred between 2.5 and 5 hr after the treatment. On the other hand, the phosphorylation of epidermal growth factor receptor (EGFR) was transiently observed at 29 hr after the injection. The peak of ornithine decarboxylase activity as a marker of G1 phase was at 10 hr, and subsequently the labeling index of proliferating cell nuclear antigen as a marker of S phase increased at 53 hr. These results indicate that the repetitive activation of ERK2 related to the phosphorylation of c-MET and EGFR is required for the renal regeneration in HgCl2-induced ARF of rat.

Acute Kidney Injury↗
PubMed1998

Effects of oral hyposensitization with recombinant Der f2 on immediate airway constriction in a murine allergic model.

Recombinant Der f2 (rDer f2) has recently been developed as a promising allergen for the diagnosis and immunotherapy of house-dust mite allergy, and studies in immunology. The aim of the present study was to evaluate whether oral administration of rDer f2 could suppress an immediate allergic reaction in mice sensitized with mite allergen. We developed a murine allergic model that showed bronchoconstriction after inhalation of rDer f2, and studied the effect of oral administration of rDer f2 on the reaction. Seven week old male A/J mice were intranasally immunized with rDer f2 12 times. Sensitized mice showed anti-rDer f2 immunoglobulin (Ig)E production and immediate airway constriction after inhalation of 10 mg.mL(-1) of rDer f2, as determined by the Konzett-Rössler method. Immunized animals were divided into three groups, and fed phosphate-buffered saline (PBS), 0.1 mg.day(-1), or 1 mg.day(-1) of rDer f2 for 4 weeks, respectively. Seven days after the last feeding, the mice were examined for their immediate response. Animals fed with 1 mg.day(-1) rDer f2 showed significantly reduced bronchoconstriction after inhalation of both 2 mg.mL(-1) and 10 mg.mL(-1) of rDer f2 compared with PBS-fed mice. Similar results were obtained when we examined mice 10 weeks after the last feeding. Reactions in the 0.1 mg.day(-1) rDer f2-fed group also tended to decrease in comparison with PBS-fed animals. Plasma anti-rDer f2 IgE, IgG1, IgG2a, and IgG2b levels were not changed by feeding with rDer f2. We conclude that recombinant Der f2 exhibits both sensitizing and hyposensitizing activities in mice. rDer f2 may be useful in immunotherapy and diagnosis of house-dust mite allergy.

Administration, Oral↗
PubMed1998

[Detection of recurrent rectal cancer using helical CT with SmartPrep: a new technique for obtaining optimal contrast enhancement].

Seven patients with suspected recurrent rectal cancer underwent Helical CT using SmartPrep. SmartPrep is a software application developed by GE in which the ROI is placed at the desired level of the aorta prior to contrast injection. Using a low-dose continuous scan, the time density curve was obtained instantly, and the optimal timing of scanning was judged from the curve. Four patients who demonstrated intense enhancement at the anastomotic site had local recurrence. No intense enhancement was observed in these areas on conventional delayed CT. Thus, SmartPrep appears to be useful for the accurate diagnosis of recurrent rectal cancer.

Aged↗