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Biomedical subjects

H Oku

Publications and source records attributed to H Oku.

At least 55 records · Page 3Linked to original sources
PubMed2000

Testosterone 5alpha-reductase inhibitor bisnaphthoquinone derivative from Impatiens balsamina.

The 35% EtOH extract of aerial parts of Impatiens balsamina L. has been investigated for activity against testosterone 5alpha-reductase. Activity-guided fractionation led to the identification of the bisnaphthquione derivative named impatienol (1), 3-hydroxy-2-¿[3-hydroxy-1,4-dioxo (2-naphthyl)] ethyl¿ naphthalene-1, 4-dione, which exhibited significant testosterone 5alpha-reductase inhibitory activity. This 5alpha-reductase inhibitory compound has been previously synthesized, but this is the first report of its isolation from a natural source.

5-alpha Reductase Inhibitors↗
PubMed2000

Soybean-milk-coagulating activity of Bacillus pumilus derives from a serine proteinase.

A proteolytic enzyme from Bacillus pumilus strain TYO-67, which was able to coagulate the protein in soybean milk, was characterized enzymologically. The optimum pH and temperature for its activities were 9.0 and 50 degrees C, respectively. The enzyme was strongly believed to be a serine proteinase because it was completely inhibited by the addition of diisopropyl fluorophosphate or phenylmethanesulfonyl fluoride. Hammerstein milk casein, cytochrome c and soybean protein were good substrates for the enzyme. Seven cleavages were detected using the oxidized insulin B-chain as peptide substrate for the proteolytic specificity test of the serine proteinase from B. pumilus. The bonds most susceptible to the action of the serine proteinase from B. pumilus were Leu-15-Tyr-16. The mode of action on soybean milk protein by the enzyme from B. pumilus was also investigated. The acidic subunit in glycinin and the alpha-, alpha- and beta-subunits in beta-conglycinin were degraded during the enzyme reaction. However, the basic subunit in glycinin could not be degraded by the enzyme. The formation of coagula in soybean milk caused by the serine proteinase from B. pumilus was mainly due to the hydrophobic interaction.

Bacillus↗
PubMed2000

Biased distribution of the branched-chain fatty acids in ceramides of vernix caseosa.

The compositions of ester- and amide-linked fatty acids from ceramides of human vernix caseosa were described with emphasis on the distribution of the branched-chain fatty acid (BCFA). Two novel ceramides were isolated from vernix caseosa in the course of this study: the acylated type of esterified alpha-OH-hydroxyacid/sphingosine ceramide (Cer[EAS]) and nonacylated type of non-OH fatty acid/hydroxysphingosine ceramide (Cer[NH]). Their chemical structures were identified by nuclear magnetic resonance and chemical procedure. The Cer[EAS] was an acylceramide and consisted of the highest concentrations of ester- and amide-linked BCFA (62 and 67%, respectively). The iso- or anteiso-branching structures of the aliphatic chains were confirmed by the mass spectra of their picolinyl or pyrrolidide derivatives. As a whole, amide-linked fatty acids of ceramides 1-7 and Cer[NH] were normal types of straight-chain fatty acids with or without alpha- or omega-hydroxylation. The BCFA concentrations of amide-linked fatty acids in these ceramides (ceramides 1-7 and Cer[NH]) were low and less than 10%. The BCFA thus occurred exclusively in a novel acylceramide of Cer[EAS] in the vernix caseosa.

Ceramides↗
PubMed2000

Expanded polytetrafluoroethylene monocuspid valve for right ventricular outflow tract reconstruction.

BACKGROUND: Numerous materials have been used for reconstruction of the right ventricular outflow tract (RVOT) in patients with complex congenital heart defects. METHODS: Between January 1982 and March 1999, 19 patients (10 boys and 9 girls; mean age, 8.5 years) with severe RVOT obstruction underwent reconstruction using a transannular patch and expanded polytetrafluoroethylene (ePTFE) monocuspid valve. RESULTS: There were no perioperative deaths. Postoperatively, the mean +/- standard deviation RVOT gradient was 12 +/- 9 mm Hg. Echocardiography showed good motion of all cusps, and most had no or trivial pulmonary regurgitation. The difference between the preoperative and postoperative mean ratio of right-to-left ventricular peak systolic pressure was significant (p = 0.0001). In the 8 patients followed for 3 years or longer, pulmonary regurgitation was mild or better in 5 and moderate in 2, and the mean peak systolic RVOT gradient was 16.3 +/- 5.9 mm Hg. Five patients had good mobility of the monocusps. Two patients needed reoperation because of stenosis at the distal anastomosis of the transannular patch; 1 patient died. CONCLUSIONS: The ePTFE monocuspid valve may be useful in reconstruction of the RVOT.

Adolescent↗
PubMed2000

Coronary artery bypass grafting following substernal gastric interposition.

A 61-year-old man who had undergone substernal esophagogastric anastomosis for reconstruction after esophageal cancer, developed unstable angina 9 years later. Complete revascularization for triple-vessel disease was performed via a left thoracotomy approach under cardiopulmonary bypass. The successful results show that complete revascularization can be performed via this approach.

Angina, Unstable↗
PubMed2000

Increased cholesterol absorption by hyperlipidemia atherosclerosis prone (LAP) Japanese quail.

The present study describes the cholesterol absorption by hyperlipidemia atherosclerosis prone (LAP) Japanese quail to address their high susceptibility to experimental atherosclerosis. The apparent cholesterol absorption rate of LAP quail was compared with that of commercially available (CA) Japanese quail. After 14 d of cholesterol feeding by gavage, it was found that the cholesterol excretion of LAP quail was significantly lower than that of CA quail. The fecal excretion of bile acid and fat showed a similar tendency to that as shown with the case of cholesterol. The cholesterol feeding only increased the serum cholesterol level of LAP quail, and this trend holds true for the liver lipid concentration. The expression level of liver cholesterol 7alpha-hydroxylase mRNA showed no difference between LAP and CA strains under the conditions of cholesterol loading. These results showed that the cholesterol absorption by LAP quail is significantly higher than that by CA quail, which may reasonably explain the higher susceptibility of this strain to experimental atherosclerosis.

Animals↗
PubMed2000

Improving effects of topical administration of iganidipine, a new calcium channel blocker, on the impaired visual evoked potential after endothelin-1 injection into the vitreous body of rabbits.

PURPOSE: To investigate the effect of topical iganidipine, a new dihydropyridine derivative calcium channel blocker, on impairment of the ocular circulation caused by endothelin-1 (ET-1), we examined modification of the effect of ET-1 on visual-evoked potential (VEP) in albino rabbits. METHODS: To clarify whether VEP could be used to indicate the extent of ocular circulatory impairment, we evaluated the dose dependency of changes in VEP over 2 hours after intravitreal injection of 3 ET-1 doses (1.0, 3.3, or 10 pmol) and the vehicle. Then modification of the effect of ET-1 on the VEP by iganidipine was examined. One hour after the topical instillation of 0.1% iganidipine (20 microl) or its vehicle, 10 pmol of ET-1 was injected into the vitreous in rabbits. The VEP was measured for 2 hours after ET-1 application, and the response was compared between the eyes with iganidipine and vehicle pretreatment. RESULTS: Intravitreal injection of ET-1 dose-dependently reduced the VEP amplitude. Topical administration of 0.1% iganidipine significantly suppressed the reduction of VEP amplitude for the entire 2-hour monitoring period after intravitreal injection of 10 pmol ET-1. There was no significant change of the systemic blood pressure as well as intraocular pressure after topical administration of iganidipine. CONCLUSIONS: Iganidipine eyedrops may be useful for the treatment of ischemic retinal and optic nerve disorders related to abnormal ET-1 production for the maintenance of visual function.

Administration, Topical↗
PubMed2000

Effect of nitric oxide synthase inhibitor on optic nerve head circulation in conscious rabbits.

PURPOSE: To study the effect of a nitric oxide synthase inhibitor on tissue circulation in the optic nerve head (ONH) of conscious rabbits. METHODS: N(G)-nitro-L-arginine methyl ester (L-NAME) (1, 10, or 100 mg/kg), D-NAME (10 mg/kg), or physiological saline was administered intravenously to albino rabbits. A quantitative index of blood velocity, the normalized blur (NB), was measured in the ONH by laser speckle tissue circulation analyzer. The intraocular pressure (IOP) and blood pressure (BP) were also measured. L-arginine (10 mg/kg) was intravenously administered 20 minutes after L-NAME (10 mg/kg) injection. Acetylcholine (ACh; 10 microg/kg per minute) was infused for 15 minutes, with or without pretreatment of L-NAME (1 mg/kg). RESULTS: L-NAME induced a continuous decrease of the NB in a dose-dependent manner, but D-NAME caused no significant change. At 100 mg/kg, L-NAME significantly increased the IOP, mean BP, and ocular perfusion pressure, but the other doses caused no significant changes. When L-arginine was administered after L-NAME injection, the NB returned to its initial level and remained there. Pretreatment with L-NAME inhibited the increase of NB induced by ACh. CONCLUSIONS: These results indicate that nitric oxide regulates basal tissue circulation in the ONH of conscious rabbits and suggest that ACh increases the circulation by promoting nitric oxide synthesis.

Acetylcholine↗
PubMed2000

Coronary artery bypass grafting in octogenarians.

The aging of the Japanese population and improvements in surgical techniques have resulted in an increasing number of elderly patients undergoing coronary artery bypass grafting (CABG). We reviewed the records of 11 patients 80 years of age or older (mean age 82+/-0.38 years, range, 80 to 85 years) who had undergone a CABG at our institution between August 1989 and February 1999. Eight patients were males and 3 were females. Preoperatively, 4 of 11 patients were categorized as New York Heart Association class II, 4 as class III, 3 as class II. The operations were elective in 8 cases, and emergent in 3. Three patients presented with neck and cerebrovascular disease. One patient experienced chronic renal failure. No patients died within 30 postoperative days and no in-hospital deaths occurred. A total of 11 were followed up for an average of 35+/-11 months (range, 1 to 105 months). One patient died due to unknown causes. There was a significant decrease in overall anginal symptoms after CABG among the survivors, with the average decrease being from NYHA class 3.1 to 1.5. In conclusion, CABG is a safe and effective surgical procedure in the treatment of octogenarians with heart disease.

Aged↗
PubMed1999

Screening method for PAF antagonist substances: on the phenolic compounds from Impatients balsamina L.

A blood pressure monitoring system was developed for studying antagonist effects against platelet activating factor (PAF), a chemical mediator of anaphylactic hypotension. Using this system, we were able to determine the inhibitory effects of a 35% ethanol extract (IB) from the petals of Impatiens balsamina L. against PAF-induced hypotension and the active principal compounds from IB. One mechanism of the antianaphylactic effects of IB was characterized as PAF-antagonist effects.

Anaphylaxis↗
PubMed1999

Further optimization of culture method for rat keratinocytes: titration of glucose and sodium chloride.

The present study further improved the serum-free method of culturing rat keratinocytes. To obtain the best growth of rat keratinocytes, we modified our previous serum-free medium (MCDB153 based medium), particularly the amounts of glucose and sodium chloride (NaCl). Titration experiments showed the optimal concentration to be 0.8 mM for glucose and 100 mM for NaCl. This modification eliminated the requirement for albumin, which had been essential for colony formation when our previous medium was used. Titration of glucose and NaCl, followed by adjustment of essential amino acids and growth factors, produced a new formulation. More satisfactory and better growth was achieved with the new medium than with the previous medium. Accumulation of monoalkyldiacylglycerol (MADAG) was consistently noted in this study, representing the unusual lipid profile. A tendency toward normalization was, however, noted with the neutral lipid profile of keratinocytes cultivated in the new medium: lower production of MADAG was obtained with the new formulation, rather than the previous one.

Amino Acids↗
PubMed1999

Beneficial effects of omega-3 fatty acid treatment on the recovery of cardiac function after cold storage of hyperlipidemic rats.

Cardiac effects of omega-3 polyunsaturated fatty acids (PUFAs) were studied in female Wister rats fed a standard diet (control [C] diet) or a high-cholesterol (HC) diet. Subgroups of rats from these groups were treated with eicosapentaenoic acid-E (EPA) or docosahexaenoic acid-95E (DHA) for 5 weeks. Although plasma total cholesterol (TC) and triglyceride (TG) levels were higher in each group fed the HC diet versus each group fed the C diet, EPA administration with the HC diet (HC + EPA) significantly (P < .05) reduced these levels. An isolated working-heart preparation was used to determine cardiac function. Cardiac output (CO) was lower in rats fed the HC diet and HC + DHA versus any of the groups fed the C diet (P < .05). In addition, left ventricular (LV) maximum differentiation of pressure-time curve (dp/dt) was lower in the rats fed the HC diet versus any of the C diet groups (P < .05). After evaluation of cardiac function in each rat, the heart was stored in a histidine-tryptophan-ketoglutarate solution for 8 hours at 4 degrees C. The heart was then reperfused, and recovery of cardiac function was evaluated. No significant differences were observed for post-preservative cardiac function within the C diet groups. However, within the HC diet groups, HC + EPA significantly (P < .05) improved the recovery of cardiac function. In addition, HC + DHA also significantly (P < .05) improved the recovery of coronary flow (CF) and LV dp/dt. No significant differences were observed for plasma TC and TG concentrations in the C diet groups. EPA administration significantly decreased cardiac levels of palmitic, oleic, and linoleic acids in the HC diet groups. No significant differences were observed for cardiac levels of free fatty acids (FFAs) within the C diet groups. Cardiac EPA and DHA levels were significantly (P < .05) elevated in EPA- or DHA-treated rats compared with the other diet-fed rats. Cardiac EPA levels were also elevated in DHA-treated rats compared with untreated rats (P < .05). These results suggest that EPA attenuates coronary and myocardial preservation injuries through an increase in serum lipids and an accumulation of myocardial FFAs resulting from a HC diet.

Animals↗
PubMed1999

Experimental optic cup enlargement caused by endothelin-1-induced chronic optic nerve head ischemia.

PURPOSE: Vascular insufficiency of the optic nerve head may contribute to glaucomatous optic neuropathy, especially in normal-tension glaucoma. We investigated the effect of chronic optic nerve head ischemia, created by repeated intravitreal injection of endothelin-1 (ET-1), on the morphology and function of the optic nerve. METHODS: In pigmented rabbits, we injected ET-1 (10(-6) M, 10 microL) into the posterior vitreous of one eye twice a week for 4 weeks (N = 7). The vehicle for ET-1 was injected into the contralateral eye as a control (N = 7). The subsequent observation period was set at 8 weeks. The microcirculation of the optic nerve head was noninvasively monitored with a laser speckle circulation analyzer. To evaluate the changes of visual function, visual-evoked potentials were recorded. Morphologic changes of the optic nerve head were analyzed with stereography, and the ratio of cup area (CA) to disk area (DA) was measured by calculating the number of pixels in each area with a microcomputer. RESULTS: Capillary blood flow in the optic nerve head was continuously below 80% of the baseline throughout the study. The visual-evoked potential latency was significantly delayed in ET-1-treated eyes. The CA/DA ratio was significantly increased relative to baseline in the ET-1 treated eyes. Histologic examination showed axonal loss and demyelination affecting the prelaminar portion of the optic nerve. The intraocular pressure was not significantly different from the control value. CONCLUSION: Optic nerve head ischemia could contribute to the enlargement and excavation of the disk cup independent of the intraocular pressure level.

Animals↗
PubMed1999

Establishment of nurse-like stromal cells from bone marrow of patients with rheumatoid arthritis: indication of characteristic bone marrow microenvironment in patients with rheumatoid arthritis.

OBJECTIVE: To investigate the microenvironment of bone marrow (BM) of patients with rheumatoid arthritis (RA). METHODS: Nurse cell-like BM stromal cell lines were established from BM mononuclear cells of patients with RA. We examined the various characteristics of these cell lines, including morphology, pseudoemperipolesis activity, cell surface markers, cytokine production and hyaluronan (HA) production. RESULTS: These RA BM nurse cell-like lines (RA-BMNC) were of mesenchymal origin and positive for CD44, CD54 and HLA-DR. They were defined as nurse cells because of pseudoemperipolesis activity that allowed lymphocytes to migrate underneath. RA-BMNC lines produced HA and multiple cytokines including interleukin (IL)-6, IL-7, IL-8 and granulocyte-macrophage colony-stimulating factor (GM-CSF). HA production by BM stromal cells was correlated with pseudoemperipolesis activity. RA-BMNC produced significantly higher levels of IL-6, IL-8 and GM-CSF by co-culture with lymphocytes. The cells also produced IL-1beta, G-CSF and tumour necrosis factor only when co-cultured with lymphocytes. The RA-BMNC maintained the growth of CD14+ myeloid cells unique to severe RA. CONCLUSION: The present results both indicate that RA-BMNC are nurse cells and suggest that they may play an important role in the pathogenesis of RA.

Antigens, CD↗
PubMed1999

Apolipoprotein A-I of hyperlipidemia atherosclerosis prone (LAP) quail: cDNA sequence and tissue expression.

Apolipoprotein A-I (apo A-I) has an important role in the transport of cholesterol. This study describes the complete nucleotide and deduced amino acid sequence for apo A-I of LAP quail. A full length apo A-I cDNA clone for hyperlipidemia atherosclerosis prone (LAP) quail was isolated from a lambda gt10 liver cDNA library. The DNA sequence of LAP apo A-I cDNA was similar to that of normal Japanese quail. The deduced amino acid sequence of LAP apo A-I was hence identical to that of normal Japanese quail. LAP apo A-I mRNA is about 1.4 kilobases in length and expressed in a variety of tissues including small intestine, liver, lung, breast muscle, testis, and heart. Although the tissue distribution of apo A-I was similar between strains, LAP quail expressed more apo A-I mRNA than normal Japanese quail in all tissues examined. This tendency was pronounced with the small intestine. Although the concentration of serum apo A-I did not correlate with the tissue expression of mRNA, the observation may suggest that the increased apo A-I expression in LAP strain had some relevance to the susceptibility of this strain to the experimental atherosclerosis.

Amino Acid Sequence↗