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Biomedical subjects

H Urata

Publications and source records attributed to H Urata.

At least 37 records · Page 2Linked to original sources
PubMed2000

A new approach to develop a biohybrid artificial liver using a tightly regulated human hepatocyte cell line.

Currently patients with liver failure have been treated with a various liver support systems including a whole liver perfusion, a non-biological artificial liver, and a biohybrid artificial liver. In a hepatocyte-based bioreactor, porcine hepatocytes or transformed human liver tumor cells have been utilized because of the ease of preparation. According to the clinical data reported as of now, satisfactory results have not been obtained from the use of currently available liver support devices. One of the problems is limited availability of primary human liver cells for developing live support systems because of the shortage of human liver. To resolve this issue, human hepatocytes were immortalized with a retroviral vector SSR#69 which contained the genes of simian virus 40 large T antigen (SV40Tag) and herpes simplex virus-thymidine kinase (HSV-TK). One of the immortal cell lines, NKNT-3, showed the gene expression of differentiated liver functions, grew steadily in chemically defined serum-free CS-C medium, and doubled in number in about 48 hours. Essentially unlimited availability of NKNT-3 cells supports their clinical use for liver support devices. To realize the high density culture of NKNT-3 cells in a bioartificial liver device, we have developed cellulose microspheres (CMS) which contain cell adhesive GRGDS (Gly-Arg-Gly-Asp-Ser) peptides. Within 24 hours after starting a stirring suspension culture, GRGDS-CMS efficiently immobilized NKNT-3 cells. An electron microscopic examination demonstrated that NKNT-3 cells attached on GRGDS-CMS had well-developed mitochondria, rough reticulums, and villous extensions. In this article, we review the history of extracorporeal liver support systems and describe an attractive strategy for developing a novel extracorporeal liver assist device using NKNT-3 cells and GRGDS-coated cellulose microspheres.

Animals↗
PubMed1999

Decreased skeletal muscle capillary density is related to higher serum levels of low-density lipoprotein cholesterol and apolipoprotein B in men.

The relationships between skeletal muscle morphology, particularly muscle fiber capillary density, and serum lipid profiles were evaluated in 25 non-obese men aged 18 to 36 years (body mass index [BMI], 22.7 +/- 2.5 kg/m2; body fat, 13.6% +/- 4.0%, maximal oxygen uptake [VO2max], 46.2 < or = 6.3 mL/kg/min). Skeletal muscle samples were taken from the vastus lateralis using the needle-biopsy method. The fiber types (I, IIa, and IIx) and their percent distribution, the indices of capillary density, and the diffusion index expressed as the cross-sectional area occupied by one capillary were determined. Blood samples were drawn from the antecubital vein after a 12-hour fast. Based on Pearson's correlation analysis, the number of capillaries around type IIx fiber correlated inversely with the serum level of low-density lipoprotein cholesterol ([LDL-C] r = -.50, P < .05). The number of capillaries per fiber (cap/fiber ratio), number of capillaries per area (cap/mm2), and capillaries around each fiber type correlated inversely with the serum level of apolipoprotein B ([apo B] r = -.40 to -.54, P < .05 to .01). Further, the diffusion index for each fiber type correlated positively with LDL-C and apo B (r = .42 to .50, P < .05 to .01). Among 14 subjects in whom high-density lipoprotein cholesterol (HDL-C) subfractions were analyzed, a positive correlation was found between cap/mm2 and HDL2-C (r = .64, P < .05). Partial correlation analysis showed that these correlations either remain or improve after adjusting for age, VO2max, and body fatness. These results indicate that skeletal muscle capillary density and diffusion capacity are related to lipid and apolipoprotein concentrations for both type I and type II fibers.

Adipose Tissue↗
PubMed1999

Synthesis and properties of oligonucleotides containing carbocyclic L-nucleoside analogues with a restricted glycosyl conformation.

To construct nuclease-resistant oligonucleotides, we designed novel carbocyclic L-nucleoside analogues (1-4) whose glycosyl conformation is fixed at chi = 180 degrees by an oxygen-bridge between the base and the cyclopentane ring. We have already achieved the racemic synthesis of these analogues. In this study, we succeeded in synthesizing an optically active form of these analogues. The properties of oligonucleotides containing them will be shown.

Cyclopentanes↗
PubMed1999

Increased chymase-dependent angiotensin II formation in human atherosclerotic aorta.

Locally formed angiotensin II (Ang II) and mast cells may participate in the development of atherosclerosis. Chymase, which originates from mast cells, is the major Ang II-forming enzyme in the human heart and aorta in vitro. The aim of the present study was to investigate aortic Ang II-forming activity (AIIFA) and the histochemical localization of each Ang II-forming enzyme in the atheromatous human aorta. Specimens of normal (n=9), atherosclerotic (n=8), and aneurysmal (n=6) human aortas were obtained at autopsy or cardiovascular surgery from 23 subjects (16 men, 7 women). The total, angiotensin-converting enzyme (ACE)-dependent, and chymase-dependent AIIFAs in aortic specimens were determined. The histologic and cellular localization of chymase and ACE were determined by immunocytochemistry. Total AIIFA was significantly higher in atherosclerotic and aneurysmal lesions than in normal aortas. Most of AIIFA in the human aorta in vitro was chymase-dependent in both normal (82%) and atherosclerotic aortas (90%). Immunocytochemical staining of the corresponding aortic sections with antichymase, antitryptase or anti-ACE antibodies showed that chymase-positive mast cells were located in the tunica adventitia of normal and atheromatous aortas, whereas ACE-positive cells were localized in endothelial cells of normal aorta and in macrophages of atheromatous neointima. The density of chymase- and tryptase-positive mast cells in the atherosclerotic lesions was slightly but not significantly higher than that in the normal aortas, and the number of activated mast cells in the aneurysmal lesions (18%) was significantly higher than in atherosclerotic (5%) and normal (1%) aortas. Our results suggest that local Ang II formation is increased in atherosclerotic lesions and that chymase is primarily responsible for this increase. The histologic localization and potential roles of chymase in the development of atherosclerotic lesions appear to be different from those of ACE.

Aged↗
PubMed1999

[Effect of chirality of ribose on nucleic acid structure and function].

Organisms utilize the only D-enantiomer of ribose as a sugar unit of nucleic acids. This homochirality of nucleic acids is considered to be essential for their higher-order structures and functions. Although there had been a few reports on the synthesis of L-deoxynucleosides, effects of the substitution of L-ribose for the D-enantiomer on the structure and properties of nucleic acids have hardly been investigated due to difficulties in large-scale synthesis of L-deoxynucleosides. We have developed an approach for the efficient, short step synthesis of L-deoxynucleosides, and have investigated the structure and properties of oligonucleotides containing them. The double-helical conformations of an L-hexadeoxynucleotide, L-d(CGCGCG) were clearly shown to be an exact mirror image of those of the corresponding natural one by CD (circular dichroism) and X-ray crystallographic analysis. This L-hexadeoxynucleotide was applied to the study of the specific double-stranded DNA recognition mechanism of bleomycin. It was found that the conventional DNA-binding domain of bleomycin binds to the L-hexadeoxynucleotide to essentially the same extent as natural one, although bleomycin can not cleave it. This result suggests that the DNA-binding domain is not responsible for the specific DNA recognition. Thus, L-DNA would be useful for distinguishing between enantio-specific and nonspecific interactions in DNA-drug interaction studies. The structures of heterochiral oligonucleotides, which contain an unnatural L-nucleotide residue in the sequence of natural type of DNA chains, were investigated by UV and 1H-NMR experiments. The results demonstrated that the L-nucleotide residue in the heterochiral oligonucleotide forms stable Watson-Crick base-pairing with the complementary natural residue, while the overall duplex stability is slightly decreased. The unusual conformational features of the L-nucleotide residue in the heterochiral DNA may be useful for the design of a novel antisense molecule resistant to nucleases in vivo.

Anti-Bacterial Agents↗
PubMed1999

Mast cells in rapidly progressive glomerulonephritis.

The role of mast cells (MC) in tubulointerstitial damage in glomerulonephritis (GN) is not fully understood. The distribution of MC was compared in renal biopsies from 50 patients with different stages of rapidly progressive GN (RPGN) and in 20 control samples. The immunoreactivity of renal MC with anti-tryptase and anti-chymase antibodies was studied. Interstitial myofibroblasts were stained with anti-alpha-smooth muscle actin (alpha-SMA) antibody, and inflammatory cells were identified by anti-CD3, -CD20, and -CD68 monoclonal antibodies. Positively stained cells were counted, and the relative interstitial and fractional areas of anti-alpha-SMA-stained cells were measured. MC were rarely found in control samples. In contrast, samples showing crescentic GN contained numerous tryptase-positive MC (MC(T)) (43.7+/-4.65 versus 7.14+/-1.3/mm2) and fewer tryptase- and chymase-positive MC (MC(TC)) (13.8+/-1.86 versus 1.89+/-0.86/mm2) in the renal interstitium but never in the glomerulus. Double immunostaining demonstrated the presence of both phenotypes of MC. Accumulation of MC was significantly correlated with the numbers of T lymphocytes (MC(T), r = 0.67) and interstitial macrophages (MC(T), r = 0.455). There was also a significant correlation between the number of MC(T) and the relative interstitial area. The number of MC(TC) was well correlated with the fractional area of alpha-SMA-positive interstitium (r = 0.749) and the percentage of the interstitial fibrotic area (r = 0.598). There was also a significant negative correlation between interstitial MC(TC) accumulation and creatinine clearance (r = 0.661). The density of MC(TC) was higher (1.4-fold) in advanced forms of GN associated with fibrocellular crescents and interstitial fibrosis. These results show the potential involvement of MC in the fibroproliferative process in the renal interstitium of patients with RPGN. The results indicate that these cells constitute part of the overall inflammatory cell accumulation in RPGN.

Actins↗
PubMed1998

Teratoma of the tongue in neonates: report of a case and review of the literature.

A female newborn presented with a huge mass protruding from the mouth. She had no respiratory distress but had difficulty swallowing. The mass originated from the tongue and was completely extirpated on the day of birth. The histologic diagnosis was mature teratoma. Three days later, another mass measuring 1 cm in diameter was found attached to the upper pharyngeal wall and was also completely extirpated 20 days after birth. The histologic diagnosis was also mature teratoma. The infant had a complete cleft palate, but no other malformation was found. Two years after surgery there is no sign of recurrence.

Female↗
PubMed1998

Constant infusion rates of lipid emulsions to stabilize plasma triglyceride concentrations: medium-chain triglyceride/long-chain triglyceride emulsions (MCT/LCT) versus LCT.

As medium-chain triglyceride emulsions (MCT) are more rapidly hydrolyzed than long-chain triglyceride emulsions (LCT), MCT/LCT tends to be infused faster than LCT. The purpose of the present study was to determine the most appropriate infusion rate for MCT/LCT to stabilize plasma concentrations of triglyceride (TG), being equivalent to the optimal infusion rate of the emulsion. A TG clamp was set up by raising the mean +/- SD concentrations of TG in plasma, being 1.08 +/- 0.18 delta mmol l(-1) for LCT, and 1.65 +/- 0.31 delta mmol l(-1) for MCT/LCT after a 50-min priming infusion of each emulsion. Thereafter, the infusion rate of lipid was controlled every 10 min to maintain a steady concentration of TG for a period of 150 min. A constant infusion of glucose at 0.32 g/kg body weight (BW) per h was administered for the test period. The weight-based rate of the infusion to maintain a steady state of plasma TG concentrations did not differ between MCT/LCT and LCT, being 0.125 +/- 0.013 vs 0.117 +/- 0.021 g/kg BW per h, while the molar-based infusion rate was 0.203 +/- 0.021 mmol/kg BW per h for MCT/LCT and 0.132 +/- 0.023 mmol/kg BW per h for LCT (P < 0.05). These results suggest that although 54% more molar MCT/LCT-TG can be hydrolyzed during a constant infusion, MCT/LCT should not be infused at a rate faster than 0.1 g/kg BW per h under a steady state.

Fat Emulsions, Intravenous↗
PubMed1998

Dual pathway for angiotensin II formation in human internal mammary arteries.

1. Angiotensin converting enzyme (ACE) is thought to be the main enzyme to convert antiotensin I to the vasoactive angiotensin II. Recently, in the human heart, it was found that the majority of angiotensin II formation was due to another enzyme, identified as human heart chymase. In the human vasculature however, the predominance of either ACE or non-ACE conversion of angiotensin I remains unclear. 2. To study the effects of ACE- and chymase-inhibition on angiotensin II formation in human arteries, segments of internal mammary arteries were obtained from 37 patients who underwent coronary bypass surgery. 3. Organ bath experiments showed that 100 microM captopril inhibited slightly the response to angiotensin I (pD2 from 7.09+/-0.11-6.79+/-0.10, P<0.001), while 100 microM captopril nearly abolished the response to [pro10] angiotensin I, a selective substrate for ACE, and the maximum contraction was reduced from 83+/-19%-23+/-17% of the control response (P=0.01). A significant decrease of the pD2 of angiotensin I similar to captopril was observed in the presence of 50 microM chymostatin (pD2 from 7.36+/-0.13-6.99+/-0.15, P<0.039), without influencing the maximum response. In the presence of both inhibitors, effects were much more pronounced than either inhibitor alone, and a 300 times higher dose was needed to yield a significant contraction response to angiotensin I. 4 These results indicate the presence of an ACE and a non-ACE angiontensin II forming pathway in human internal mammary arteries.

Adult↗
PubMed1998

Blood pressure lowering effect of low intensity aerobic training in elderly hypertensive patients.

PURPOSE: The purpose of this investigation was to determine the effect of 9 months of low intensity aerobic training on blood pressure in elderly hypertensive patients who were receiving antihypertensive medication. METHODS: The training group (N = 13; mean age 75.4 +/- 5.4 yr) agreed to take part in physical training using a treadmill with an exercise intensity at the blood lactate threshold (LT) for 30 min three to six times a week for 9 months. The rest (N = 13; mean age 73.1 +/- 4.2 yr) served as controls. RESULTS: The resting systolic (-15 +/- 8 mm Hg), mean (-11 +/- 6 mm Hg), and diastolic blood pressures (-9 +/- 9 mm Hg) decreased significantly after 3 months of training and the blood pressure of all participants stabilized at a significantly lower level by the end of the study (9 months) in the training group, whereas no significant changes in blood pressure were found in the control group. Both the pretraining systolic and diastolic blood pressure of those recruited patients negatively correlated with those changes after the training (SBP: P < 0.01; DBP: P < 0.05, respectively). After 1 month of detraining in five patients, the blood pressure levels were similar to those in the pretraining state. The LT increased significantly in the training group (P < 0.01). CONCLUSION: In conclusion, an additional antihypertensive effect of mild aerobic training at the LT was confirmed in elderly patients receiving antihypertensive medication. The cessation of such training in five patients, however, resulted in a relatively rapid return to pretraining levels within a month.

Aged↗
PubMed1998

Functional evidence for alternative ANG II-forming pathways in hamster cardiovascular system.

Like human chymase, hamster chymase is an ANG II-forming enzyme, but pathophysiological roles of chymase are still unknown. We determined the functional conversion of ANG I and [Pro11, D-Ala12]ANG I, a chymase-selective substrate, to ANG II in the hamster cardiovascular system. ANG I and [Pro11, D-Ala12]ANG I produced similar dose-dependent pressor responses in conscious hamsters. Captopril and CV-11974, an ANG II type 1 (AT1)-receptor antagonist, inhibited the responses to ANG I; in contrast, the pressor responses to [Pro11, D-Ala12]ANG I were suppressed only by CV-11974. In the isolated aorta, captopril suppressed ANG I-induced contraction by 84%; administration of captopril with either chymostatin or aprotinin eliminated the contraction. [Pro11, D-Ala12]ANG I-induced contraction was not affected by captopril but was attenuated by chymostatin (71%) and aprotinin (57%). CV-11974 abolished the responses to both substrates, whereas PD-123319, an AT2-receptor antagonist, had no effect. In homogenates of the aorta and heart, soybean trypsin inhibitor-inhibitable ANG II formation predominated over captopril- or aprotinin-inhibitable ANG II formation. These data suggest that [Pro11,D-Ala12]ANG I and part of ANG I were functionally converted to ANG II by chymase and other serine protease(s) in hamster vessels, inducing AT1-receptor-mediated vasoconstriction. Biochemical data supported a role for chymase in the alternative pathway.

Angiotensin I↗
PubMed1998

Differences in tissue angiotensin II-forming pathways by species and organs in vitro.

Angiotensin (Ang) II plays an important role in cardiovascular homeostasis, not only in the systemic circulation but also at the tissue level, and is involved in the remodeling of the heart and vasculature under pathological conditions. Although alternative Ang II-forming pathways are known to exist in various tissues, the details of such pathways remain unclear. The aim of this study was to examine tissue Ang II-forming activities and to identify the responsible enzyme in several organs (lung, heart, and aorta) in various species (human, hamster, rat, rabbit, dog, pig, and marmoset). Among the organs examined, the lung contained the highest Ang II-forming activity. The responsible enzyme for pulmonary Ang II formation was angiotensin I-converting enzyme (ACE) in all of the species except the human lung, in which a chymaselike enzyme was dominant. In the heart, the highest total Ang II-forming activity was observed in humans, and a chymaselike enzyme was dominant in all of the species except rabbit and pig. Aorta exhibited a relatively high total Ang II-forming activity, with a predominance of chymaselike activity in all of the species except rabbit and pig, in which ACE was dominant. Our results indicate that there were remarkable differences in Ang II-forming pathways among the species and organs we examined. To study the pathophysiological roles of ACE-independent Ang II formation, one should choose species and/or organs that have Ang II-forming pathways similar to those in humans.

Aged↗
PubMed1998

Design and racemic synthesis of conformationally restricted carbocyclic pyrimidine nucleoside analogs based on the structure of the L-nucleoside residue in heterochiral DNA.

Carbocyclic pyrimidine nucleoside analogs which have restricted glycosidic conformation at chi approximately 180 degrees were designed, based on the conformational features of the L-nucleotide residue in heterochiral DNA, and synthesized. The synthesis of (+/-)-carbocyclic 6,6'-O-cyclo-2'-deoxyuridine was achieved via bromination and subsequent intramolecular cyclization of carbocyclic 6'beta-hydroxy-2'-deoxyuridine. (+/-)-Carbocyclic 6,6'-O-cyclo-2'-deoxycytidine was synthesized from protected carbocyclic 6,6'-O-cyclo-2'-deoxyuridine via the 4-triazole intermediate.

Anti-HIV Agents↗
PubMed1997

Substituted 3-(phenylsulfonyl)-1-phenylimidazolidine-2,4-dione derivatives as novel nonpeptide inhibitors of human heart chymase.

A series of 3-(phenylsulfonyl)-1-phenylimidazolidine-2,4-dione derivatives have been synthesized and evaluated for their ability to selectively inhibit human heart chymase. The structure-activity relationship studies on these compounds gave the following results. The 1-phenyl moiety participates in a hydrophobic interaction where an optimum size is required. At this position, 3,4-dimethylphenyl is the best moiety for inhibiting chymase and showed high selectivity compared with chymotrypsin and cathepsin G. A 3-phenylsulfonyl moiety substituted with hydrogen-bond acceptors such as nitrile and methoxycarbonyl enhances its activity. Molecular-modeling studies on the interaction of 3-[(4-chlorophenyl)sulfonyl]-1-(4-chlorophenyl)-imidazolidine-2,4-dione (29) with the active site of human heart chymase suggested that the 1-phenyl moiety interacts with the hydrophobic P1 pocket, the 3-phenylsulfonyl moiety resides in the S1'-S2' subsites, and the 4-carbonyl of the imidazolidine ring and sulfonyl group interact with the oxyanion hole and the His-45 side chain of chymase, respectively. The complex model is consistent with the structure-activity relationships.

Binding Sites↗
PubMed1997

High levels of human chymase expression in the pineal and pituitary glands.

The brain renin-angiotensin system plays a role in both cardiovascular homeostasis and neurosecretory functions. Since the mechanisms of angiotensin (Ang) II formation in the human brain have not been clarified, the aims of the present study were to determine the presence of human chymase and angiotensin I-converting enzyme (ACE) in human and non-human brains. In the human brain, the total Ang II-forming activity was significantly higher in the pineal and pituitary glands than those in other regions. In other species (rat, bovine and porcine), the level of chymase as well as total Ang II-forming activities in pineal glands were significantly lower than those in human glands. High levels of chymase-like immunoreactivity (ir) were found in the arteriolar endothelial cells, adventitial mesenchymal cells and in parenchymal cells of the human pineal and pituitary glands while ACE-ir was mostly observed in the endothelial cells and occasionally found in parenchymal cells. Our study provides the first evidence that human chymase exists in the pineal and pituitary glands. The remarkable regional and species differences in mechanisms of Ang II formation suggest a specific role of chymase or ACE in the human brain.

Adult↗
PubMed1997

[Pathophysiological roles of human chymase].

Angiotensin (Ang) II plays an important role in cardiovascular homeostasis such as regulation of blood pressure and tissue remodeling. Alternative Ang II-forming pathways, independent of Ang I converting enzyme (ACE), have been reported. Several serine proteinases including kallikrein, cathepsin G and chymase appear to be involved in ACE-independent Ang II formation in vivo. Among them, biochemical analysis revealed that chymase is a highly efficient Ang II-forming enzyme with a high substrate specificity against Ang I and is rich in various human tissues. However, the pathophysiological roles of chymase have not yet been clarified. Recent reports from us and others indicated that chymase seems to be related to development of atherosclerosis, cardiomyopathy, remodeling of cardiovascular tissues, rheumatoid arthritis and etc. In this review article, the recent findings for chymase related to cardiovascular diseases are summarized.

Angiotensin II↗
PubMed1997

Healing human myocardial infarction associated with increased chymase immunoreactivity.

We studied the immunoreactivity of the chymase protein in normal human myocardium and in human myocardial infarctions at various postinfarction times using immuno-histochemistry. In noninfarcted hearts chymase was mainly present in cardiomyocytes and endothelial cells. At 6 h after infarction the ischemic cardiomyocytes had lost their chymase immunoreactivity. A portion of the smooth muscle alpha-actin-expressing myofibroblasts and some of the CD-68-positive macrophages, which both appear 4-6 days after infarction, contained chymase. Chymase was also found in mast cells, which were present in the normal myocardium and the healing scar. These data show that chymase, a protein that mediates the conversion of angiotensin I to angiotensin II via a non-angiotensin-converting-enzyme-dependent pathway is present in the normal adult human myocardium and is upregulated in the healing tissue after myocardial infarction.

Chymases↗