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H Doi

Publications and source records attributed to H Doi.

At least 145 records · Page 8Linked to original sources
PubMed1996

Codon usage tabulated from the international DNA sequence databases.

Codon usage in 87 602 genes has been calculated using the nucleotide sequence data obtained from the GenBank Genetic Sequence Data Bank (Release 90.0; September 1995). The database is called the CUTG Database; the complete form of the database can be obtained by anonymous ftp from DDBJ and a part of the database, which lists the frequency of codon use in each organism, is made searchable through our World Wide Web server.

Base Sequence↗
PubMed1996

Serial passage of human immunodeficiency virus type 1 generates misalignment deletions in non-essential accessory genes.

Human immunodeficiency virus type 1 (HIV-1) derived from an infectious molecular clone pNL432 was extensively passaged in tissue culture by repeated rounds of acute infection. We previously showed the natural occurrence of a nonsense mutation in the vpr gene during continued passage of this virus. In this report, we show that two forms of large deletions (561 and 518 base pairs containing short direct repeats at the deletion junctions) occur after passage 50 in the region that spans the vif and vpr open reading frames. One model to explain the occurrence of these deletion regions is that such mutations result from misalignment of the growing point at a limited number of nucleotide positions. Infection of CD4+ T-cells with a recombinant HIV-1 construct containing the same vif to vpr deletion showed virtually no cytopathogenic phenotype. Thus, misalignment deletions at non-essential accessory genes of HIV-1 might be induced during replication, which result in the generation of virus with a low cytopathogenic potential.

Base Sequence↗
PubMed1996

Prolonging action of imidapril on the lifespan expectancy of cardiomyopathic hamsters.

We studied the effect of imidapril, a novel angiotensin-converting enzyme (ACE) inhibitor, on lifespan expectancy of cardiomyopathic (CM) hamsters of BIO 14.6 strain, one of the representative models of congestive heart failure (CHF). Imidapril was consecutively administered to hamsters by mixing it in their diet at a concentration of 480 ppm (approximately 30 mg/kg/day) or 1,600 ppm (approximately 120 mg/kg/day) from age 26 weeks. Only several control hamsters died before age 54 weeks, but their survival rate decreased to 23.7% at age 73 weeks. The survival rates of 480-ppm and 1,600-ppm imidapril groups at age 73 weeks were as high as 75.7 and 68.4%, respectively (p < 0.01 vs. control hamsters). Macroscopic and microscopic pathology in imidapril-treated groups was milder than that in control animals in general, but differences were not statistically significant when animals were divided into survivors and fatalities except for the presence of mural thrombus in the heart. We further studied the effects of imidapril on blood pressure (BP), in vivo cardiac function, cardiac beta-adrenoceptor distribution, and plasma catecholamine levels after dietary treatment with 480 ppm imidapril for 8-10 weeks from age 37 weeks. Imidapril-treated animals showed improved cardiac function under urethane anesthesia. These results indicate that imidapril prolongs lifespan expectancy of CM hamsters and suggest that a hemodynamic effect of imidapril is involved in its beneficial effect.

Adrenergic beta-Agonists↗
PubMed1996

Genotype analysis of hepatitis C virus among blood donors and inmates in Metro Manila, The Philippines.

Antibodies against hepatitis C virus (HCV) were detected in 18 (2.3%) of 800 sera from commercial blood donors and 23 (4.6%) of 502 sera from inmates in Metro Manila, the Philippines. The difference in the antibody prevalence between the two groups was statistically significant (P < 0.05). HCV RNA was detected in 14 (78%) of the 18 antibody-positive sera from blood donors and 19 (83%) of the 23 antibody-positive sera from inmates. Genotype analysis revealed that HCV-2a (7%). Among inmates, on the other hand, HCV-1a (68%) was most common, followed by HCV-1b (11%), HCV-2a (5%) and HCV-2b (5%). Overall, HCV-1a and HCV-1b appeared to be predominant among them. Thus, the genotype prevalence in the Philippines was distinct from those in other Southeast Asian countries such as Thailand, Vietnam and Indonesia, and also distinct from those in the Far East including Taiwan, Mainland China and Japan.

Asia, Southeastern↗
PubMed1996

Hepatitis C virus (HCV) subtype prevalence in Chiang Mai, Thailand, and identification of novel subtypes of HCV major type 6.

Subtype analysis of hepatitis C viruses (HCVs) obtained from patients with chronic liver disease in Chiang Mai, Thailand, was performed. Of 46 HCV isolates, 13 (28%) were shown to belong to HCV subtype 3a (HCV-3a), 10 (22%) to belong to HCV-1a, 7 (15%) to belong to HCV-1b, 1 (2%) to belong to HCV-3b, and 1 (2%) to belong to a variant group, as determined from partial nucleotide sequences of the NS5B region of the viral genome. Analysis of 5' untranslated region sequences identified five other isolates (11%) of HCV type 1 and two other isolates (4%) of type 3. Detailed phylogenetic positions for the variant described above and those previously obtained from blood donors and drug addicts in Chiang Mai were determined by a six-parameter neighbor-joining method on the basis of core, E1, and NS5B region sequences. The results revealed that those sequence variants represent novel subtypes of HCV type 6. The HCV type 6 isolates appear to be antigenically different from isolates of HCV types 1 and 2, as determined by a serotyping method that utilizes recombinant peptides corresponding to a portion of the NS4 protein. The significance of subtype analysis around this area is discussed.

Adult↗
PubMed1996

Suppression of atherosclerotic changes in cholesterol-fed rabbits treated with an oral inhibitor of neutral endopeptidase 24.11 (EC 3.4.24.11).

Neutral endopeptidase 24.11 (NEP), widely distributed in the body, hydrolyzes and inactivates a number of endogenous vasoactive peptides, some of which could alter various functions of cells present in the arterial wall. Recently NEP has been found to exist in the vascular endothelium. The aim of this study was to assess the influence of chronic NEP inhibition by daily administration of UK79300 (candoxatril), an orally active NEP inhibitor (NEPI), on the development of atherosclerotic changes in high-cholesterol-fed rabbits. Male New Zealand White rabbits were fed for 8 weeks as follows: normal rabbit diet (Normal, n = 15), 1.5% cholesterol diet (Cholesterol, n = 15), or 1.5% cholesterol diet containing NEPI (20 mg.kg-1.d-1) (Cholesterol+NEPI, n = 15). At the end of the dietary period, NEPI treatment was found to suppress the surface area of the aorta covered by plaques (% surface area: Cholesterol, 59 +/- 6 versus Cholesterol+NEPI, 36 +/- 7, P < .01) and decreased contents of cholesterol and cholesterol esters in the aortas. NEPI also reduced plasma total cholesterol by 27% of Cholesterol rabbits (1781 +/- 130 mg/dL). The endothelial function, estimated by the endothelium-dependent relaxation of the isolated aortas in response to acetylcholine, was preserved in Cholesterol+NEPI rabbits compared with that in Cholesterol rabbits. NEP enzymatic activities in plasma and the particulate fraction of the homogenates from the aortas in Cholesterol rabbits were both increased, 3.1- and 3.9-fold, respectively, above those in Normal rabbits, but the activities in Cholesterol+NEPI rabbits were significantly lower than those in Cholesterol rabbits. UK73967, an active form of UK79300, or phosphoramidon partly reversed the atherosclerotic impairment of relaxation of the isolated thoracic aortic rings from Cholesterol rabbits in response to exogenous additions of C-type natriuretic peptide (CNP) and substance P, which are NEP substrates known to exist endogenously in the vascular endothelium. The results suggest that the increased NEP activity plays a significant role in atherogenesis, and NEPIs might be therapeutically useful in the prevention of atherosclerosis. Reduction of plasma cholesterol and suppression of degradations in the arteries of endogenously released CNP, substance P, or possibly other kinins known to have anti-atherosclerotic actions may at least partially contribute to the inhibitory effects of NEPIs on atherosclerotic changes.

Administration, Oral↗
PubMed1996

Prolongation of the life span of cardiomyopathic hamster by the adrenergic beta 1-selective partial agonist denopamine.

Influence of cardiotonic agents on the prognosis of heart failure depends on the individual therapeutic agents, and favorable and unfavorable effects of these agents have been reported in clinical trials. We studied the effect of the cardiotonic agent denopamine on the life span of cardiomyopathic hamsters (BIO 14.6 strain) in the heart failure period. Non-treated hamsters started to die at 40 weeks of age, and their survival rate decreased to 23.8% at the age of 65 weeks. Hamsters treated with denopamine (400 ppm in diet) from 36 weeks of age did not die until the age of 52 weeks, except in cases of accidental death. The survival rate of this group at 65 weeks of age was about 40%. Survival rates of these 2 groups were significantly different (P < 0.05) when animals with accidental death were excluded. To elucidate the mechanism of the effect of denopamine, we performed several experiments after dietary treatment with denopamine for 4 to 6 weeks from 37 weeks of age. Denopamine treatment lowered plasma levels of noradrenaline and dopamine (P < 0.05), but affected neither the cardiac contractility nor the beta-adrenoceptor density. In summary, denopamine significantly decreases the mortality of cardiomyopathic hamsters. Its effect to lower the plasma catecholamine levels may be responsible for the beneficial effect of denopamine.

Adrenergic beta-1 Receptor Agonists↗
PubMed1996

[Flow cytometric measurement of DCFH-oxidation of neutrophils in peripheral whole blood, isolated leukocytes and cerebrospinal fluid cells].

Using 2',7'-dichlorofluorescein diacetate (DCFH-DA) as an indicator for the intracellular formation of H2O2 and free radicals, we measured DCFH-oxidation (DCF fluorescence) of neutrophils by flow cytometry. The DCF fluorescence intensity of unstimulated neutrophils in whole blood was the same as the autofluorescence of neutrophils. However, that of unstimulated isolated neutrophils was higher than autofluorescence. The DCF fluorescence of isolated neutrophils was higher than that of neutrophils in whole blood with or without stimuli, and was decreased to the intensity of neutrophils in whole blood by the addition of plasma or erythrocytes. The DCF fluorescence of neutrophils in whole blood indicates the oxidative state of neutrophils in vivo. The determination of DCFH-oxidation of neutrophils in isolated leukocytes is also necessary to evaluate precisely the oxidative state of neutrophils. In cerebrospinal fluid (CSF) cells from patients with meningitis, the DCF fluorescence intensity of unstimulated neutrophils was higher than the autofluorescence of CSF neutrophils. The DCF fluorescence of CSF neutrophils stimulated with PMA showed increased intensity over that of unstimulated CSF neutrophils. The DCF fluorescence of CSF neutrophils, both unstimulated and stimulated with PMA, were decreased with the addition of plasma but not with the addition of CSF.

Cerebrospinal Fluid↗
PubMed1996

[Comparison of biochemical properties of human airway tryptase isolated from mucoid sputum with those of lung mast cell tryptase].

We found a novel trypsin-like enzyme (tryptase) in sputum from patients with chronic airway diseases, and named this enzyme human airway tryptase (HAT). To clarify its physiological significance in the airway, we compared biochemical properties of purified HAT with those of purified lung mast cell tryptase (MCT). Studies with model peptide substrates showed that both the HAT and MCT preferentially cleaved the COOH-terminal side of arginine residues of certain peptides, but substrate specificities to nine synthetic model substrates of HAT differed from those of MCT. Effects of protease inhibitors on the two enzymes were examined at a concentration of 10 microM. Both the HAT and MCT were strongly inhibited by the trypsin inhibitors leupeptin, antipain, and aprotinin. An alpha-1-protease inhibitor inhibited HAT by 50%, but it did not inhibit MCT. In contrast, a secretory leukocyte protease inhibitor strongly inhibited MCT, but not HAT. Mucoid sputum from patients with chronic bronchitis contained much more HAT than MCT. These differences in biochemical properties between HAT and MCT indicate that they play different physiological roles in the airways.

Asthma↗
PubMed1996

[Simultaneous aortic root and total arch graft replacement in a patient with aortitis syndrome].

The patient was a 45-year-old female diagnosed with aortitis syndrome and aortic regurgitation (AR). She had been taking steroid therapy since 1975. She had recently developed congestive heart failure due to AR while both the ascending aorta and aortic arch were enlarged. She had no inflammatory reaction on admission. An aortogram showed heavy dilation of both the ascending aorta and aortic arch and maximum diameters was 11 cm in the ascending aorta and 4.5 cm in the descending aorta. There was an obstruction of the left subclavian artery. Moderate AR was seen on an echocardiogram. She had a simultaneous graft replacement of aortic root and total arch. The aortic root was replaced with composite graft and coronary arteries were implanted using Carrel's patch technique, and the aortic arch was also replaced with a graft with two side branches. The postoperative course was uneventful without complication of cerebral infarction or paraplegia. The postoperative aortogram showed stenosis of the left carotid artery, but no abnormality of the coronary orifices and graft anastomosis. She returned home with disappearance of symptoms of congestive heart failure.

Aorta↗
PubMed1995

Induction of TCR-gamma delta+ cells from thymocytes stimulated by a fetal liver-derived hepatocyte clone.

We have previously reported that a fetal liver-derived hepatocyte clone, FHC-4D2, can support hematopoiesis in vitro. Here, we show that fetal thymocytes (FT) or adult thymocytes (AT) proliferate on the monolayer of FHC-4D2 cells in the presence of rIL-2. Fresh thymocytes contained few TCR-gamma delta+ cells (< 4% for FT and < 1% for AT); significant numbers of TCR-gamma delta+ cells were detected (2-11% for FT and 15-33% for AT) after the coculture with FHC-4D2 and rIL-2. Although FT-derived TCR-gamma delta+ cells predominantly used the V gamma 5 chain, the major population in AT-derived TCR-gamma delta+ cells used V gamma 1, V gamma 4, or V gamma 7 chains. Both FT- and AT-derived TCR-gamma delta+ cells killed FcR-bearing target cells when incubated with anti-TCR-gamma delta Ab. Half of FT-derived TCR-gamma delta+ cells were CD4-CD8 alpha+8 beta-; the rest were CD4-CD8 alpha-8 beta-. AT-derived TCR-gamma delta+ cells expressed neither CD4 nor CD8 molecules. Separation of thymocytes from FHC-4D2 cells with a membrane filter reduced the proliferative response by two- to threefold. Taken together, these results demonstrate that a fetal hepatocyte clone supports thymocytes to develop preferentially into TCR-gamma delta+ cells in cooperation with rIL-2 through cell-cell contact, that the repertoire and the phenotype of induced TCR-gamma delta+ cells are determined by the age of the mice, and that hepatocytes might thus play an active role in T lymphopoiesis in the fetal liver.

Age Factors↗
PubMed1995

Diverse incidences of individual oligopeptides (dipeptidic to hexapeptidic) in proteins of human, bakers' yeast, and Escherichia coli origin registered in the Swiss-Prot data base.

Oligopeptidic permutations of the 20 amino acid residues give rise to proteins of diverse functions. Our long-term goal is to produce a lexicon of oligopeptides, classifying them into at least five categories: (i) ubiquitous, (ii) function specific, (iii) group specific, (iv) species specific, and (v) nonexistent. To begin with, we report on the varying frequencies of individual oligopeptides (dipeptidic to hexapeptidic in length) found among 2862 human proteins, 1942 Saccharomyces cerevisiae proteins, and 2672 Escherichia coli proteins registered in the Swiss-Prot data base (version 29.0, released in June 1994). At all lengths (dipeptides to hexapeptides), homooligopeptides were very prominent among the most frequently occurring varieties in proteins of human and bakers' yeast origins. However, this was not the case with E. coli. While all of the expected 20(3) varieties of tripeptides were found among human proteins, three tripeptides (Cys-Cys-Trp, Trp-Trp-Cys, and Trp-Trp-His) were missing from the bakers' yeast proteins. Three tripeptides (Cys-Ile-Trp, Cys-Met-Tyr, and Cys-Trp-Trp) were also absent from E. coli proteins. Inasmuch as the Swiss-Prot data base already contained 67% of the expected total of 4000 E. coli proteins, it is virtually certain that 96,000 varieties of hexapeptides containing at least one or another of the three missing tripeptides noted above shall be nonexistent in E. coli. Furthermore, the observation of missing tripeptides in the bakers' yeast proteins suggests that nonexistent hexapeptides shall be highly phylum specific. Because of the sample size, only a small fraction of the 20(6) varieties of hexapeptides were expected to be encountered in the present survey. Indeed, only 1.2-1.5% of the possible hexapeptides were found, and the average copy number of observed hexapeptides varied between 1.06 and 1.25. Nevertheless, 33 varieties of hexapeptides occurred in 102-169 copies among human proteins. Furthermore, 15 of the 33 varieties contained such rarely used residues as Tyr, His, Cys, and Trp.

Amino Acid Sequence↗
PubMed1995

Activation of thymic B cells by signals of CD40 molecules plus interleukin-10.

We have previously found that thymic B cells, particularly thymic CD5+ B cells, show low responsiveness to the usual B cell stimulants such as lipopolysaccharide or anti-IgM plus interleukin (IL)-4, although they proliferate and produce antibodies after direct interaction with major histocompatibility complex class II-restricted T blasts. These findings raise the possibility that a CD40-CD40 ligand (L) interaction is involved in the activation of thymic B cells. In the present study, we therefore examine this possibility using CD40L-transfected Chinese hamster ovary (CHO) cells or anti-CD40 monoclonal antibody (mAb). When B cells in the spleen and peritoneal cavity were stimulated, they proliferated and produced immunoglobulin (Ig) in the presence of CD40L-CHO cells or anti-CD40 mAb alone. However, another signal delivered by IL-10 in addition to CD40L-CHO cells or anti-CD40 mAb was found to be necessary for thymic B cells to proliferate and secrete Ig. Other interleukins acting on B cells, such as IL-4, IL-5, and IL-6, had no effect on the activation of thymic B cells, which thus have unique characteristics not found in peripheral B cells. This report discusses the physiological significance of IL-10- and CD40-driven signals in the activation of thymic B cells.

Animals↗
PubMed1995

Abnormalities of B cells and dendritic cells in SAMP1 mice.

The age-related changes in the function of antigen-presenting cells (APC) were examined using a substrain of senescence-accelerated mouse (SAMP1). In the primary mixed lymphocyte reaction (MLR), dendritic cells (DC) from aged SAMP1 mice showed less stimulatory activity than those of age-matched BALB/c or young SAMP1 mice. In the secondary MLR, the stimulatory activity of B cells was found to be lower in aged SAMP1 mice but not in age-matched BALB/c or young SAMP1 mice. In addition, these age-related decreases in the stimulatory activity of APC were found to be related to changes in the surface density of major histocompatibility complex class II and intercellular adhesion molecule-1 (ICAM-1) (but not B7-1 or B7-2 molecule) on APC (DC and B cells).

Aging↗
PubMed1995

Mechanical properties of the binary titanium-zirconium alloys and their potential for biomedical materials.

Mechanical properties of titanium-zirconium binary alloys were investigated in order to reveal their possible use for new biomedical materials and to collect useful data for alloy design through a hardness test, a tensile test, and optical microscopy. The hardness of the alloy containing 50% zirconium was approximately 2.5 times as large as the hardness of pure titanium and pure zirconium. Tensile tests showed a similar tendency. No changes between hardness of as cast specimens and as homogenized specimens were observed, nor were changes in microstructures noted. Comparisons between the Ti-6Al-4V alloy and the Ti-Zr-6Al-4V alloy indicated that a titanium-zirconium alloy could provide a base material for a new biomedical alloy. From these results, it was concluded that new alloys for biomedical materials should be designed as titanium-zirconium base alloys.

Alloys↗
PubMed1995

The amino acid sequence required for 5' --> 3' exonuclease activity of Bacillus caldotenax DNA polymerase.

We studied the 5' --> 3' exonuclease activity of Bacillus caldotenax DNA polymerase by site-directed mutagenesis. Among seven mutants constructed, two mutant DNA polymerases with an amino acid substitution of Gly184 --> Asp or Gly192 --> Asp were confirmed to be deficient in this exonuclease. The two positions corresponded to those of the Escherichia coli DNA polymerase I mutants defective in 5' --> 3' exonuclease, polA480ex and polA214. These results provide experimental support for the proposed amino acid sequence essential for the 5' --> 3' exonuclease activity associated with eubacterial polymerase I-like DNA polymerases (family A), including E.coli and Thermus aquaticus.

Bacillus↗
PubMed1995

Utility of Tc-99m GSA SPECT imaging in estimation of functional volume of liver segments in health and liver diseases.

The authors examined whether there was a difference in liver function among hepatic segments in liver cirrhosis cases, and in cases of hepatocellular carcinoma (HCC) associated with liver cirrhosis. If the average counts in the lateral segment of the left lobe were set at 1, the average counts in the right upper and lower segment of the liver were 0.75 approximately 1.02 (0.89 +/- 0.09, mean +/- SD) in normal cases, 0.38 approximately 2.24 (1.01 +/- 0.39) in liver cirrhosis cases, and 0.61 approximately 2.85 (1.15 +/- 0.58) in HCC cases. There is a significant difference between normal cases and liver cirrhosis cases or HCC cases (P < 0.001). Also, in HCC cases, if the average counts in the cancer-bearing segment of the liver were set at 1, the average counts in the noncancerous segment of the liver were 0.55 approximately 2.85 (1.23 +/- 0.58), and many average counts in the cancer-bearing segment were equal to, or lower than those in the noncancerous segment. It has been found that there were significant differences in function among hepatic segments in liver cirrhosis cases, and in HCC cases. Furthermore, the liver function in the cancer-bearing segment tended to be worse due to the existence of carcinoma compared with that in the noncancerous segment.

Adult↗