Biomedical subjects

H Oku

Publications and source records attributed to H Oku.

At least 109 records · Page 6Linked to original sources

PubMed1995

[Effect of systemic calcium antagonist on a model of ocular circulation disturbance induced by endothelin-1].

We studied the effect of generally applied calcium antagonist on endothelin (ET-1) treated rabbit eyes. Nicardipine (20 micrograms/kg) was injected intravenously 15 minutes before intravitreal injection of 10 microliters of ET-1 at 10(-6) M. We measured the relative caliber of the retinal artery (the caliber of the retinal artery at the edge of the optic nerve head (ONH)/that of ONH), the capillary blood flow in ONH, visual evoked potential (VEP), intraocular pressure (IOP), and blood pressure (BP). In the control group (0.4 ml/kg of saline), administration of ET-1 caused contraction of the retinal artery, decrease of the capillary blood flow in ONH, prolongation of the VEP latency, and reduction of IOP. But these effects were significantly reduced in the calcium antagonist group. These results showed that generally applied calcium antagonist inhibits the disturbance of ocular circulation induced by ET-1. However, it also caused significant reduction of BP until 45 minutes after application, so we will have to work to find the optimum dose of calcium antagonist.

Animals↗

PubMed1995

[Midterm result of free arterial graft for myocardial revascularization].

Free arterial grafts has been used as grafts for coronary artery bypass grafting (CABG) since April 1993 in our unit and midterm patency was confirmed by coronary angiogram in 32 patients. Of 32 free arterial grafts. 23 right internal thoracic artery grafts (RITAG), 7 gastroepiploic artery grafts (GEAG) and 2 left internal thoracic artery grafts (LITAG) were placed to 38 coronary arteries including 6 grafts for sequential bypass. 20 grafts were placed in the left circumflex artery. 11 to the diagonal branch, 5 to the left anterior descending artery and 3 to the right Free arterial grafts has been used as grafts for coronary artery bypass grafting (CABG) since April 1993 in our unit and midterm patency was confirmed by coronary angiogram in 32 patients. Of 32 free arterial grafts. 23 right internal thoracic artery grafts (RITAG), 7 gastroepiploic artery grafts (GEAG) and 2 left internal thoracic artery grafts (LITAG) were placed to 38 coronary arteries including 6 grafts for sequential bypass. 20 grafts were placed in the left circumflex artery. 11 to the diagonal branch, 5 to the left anterior descending artery and 3 to the right coronary artery. Coronary angiography later than 6 months after operation revealed the patency rate of 100% for LITAG and RITAG and 81.8% for GEAG. In total 36 free arterial graft remained patent and patency rate was 94.7% and the result was comparative to the midterm patency of in situ arterial graft in our series. Free arterial grafts can be expected to offer excellent long term patency and expand the indication of arterial grafts to CABG.

Coronary Angiography↗

PubMed1994

Precursor role of branched-chain amino acids in the biosynthesis of iso and anteiso fatty acids in rat skin.

Monoester fraction of rat skin surface lipid has been shown to contain more than trace amounts of branched-long-chain fatty acids (BCFAs) of the iso and anteiso series. These BCFAs are biosynthesized using either branched-chain amino acids (BCAAs) or branched-chain alpha-keto acids (BCKAs), or using both of them as precursor. This study has been carried out to address which precursor, BCAAs or BCKAs in the circulation, are mainly utilized for biosynthesis of BCFAs. Dietary supplement of [14C]-valine and isoleucine-induced sharp rise of serum concentration of these two amino acids and their respective alpha-keto acids, and elevated the levels of related BCFAs and branched-chain fatty alcohols in the monoester fraction. A larger proportion of label in the total skin surface lipid was found in the monoester fraction in which fatty acid and alcohol accounted for approx. 80% of total radioactivity. Incorporation of intravenously administered [14C]-BCAAs and BCKAs into the monoester fraction revealed that BCAAs were far better as precursors than BCKAs for BCFA biosynthesis in rat skin. Among three BCAAs, leucine differed from valine or isoleucine in that this amino acid was primarily utilized for production of straight-chain fatty acids rather than for production of related BCFA.

Amino Acids, Branched-Chain↗

PubMed1994

Participation of nitric oxide in mouse anaphylactic hypotension.

Mouse hen egg-white lysozyme-specific anaphylaxis was estimated by monitoring changes in blood pressure by using a tail-cuff method. Stimulation of histamine H1 receptors of the vascular endothelium was suggested to be critical for mouse anaphylactic hypotension, because pretreatment with diphenhydramine but not with cimetidine completely inhibited the hypotension. Nitric oxide (NO) was indicated to play an important role in mouse anaphylaxis, because NG-nitro-L-arginine methyl ester, a NO synthase inhibitor, significantly blocked the hypotension while a large amount of L-arginine, a precursor of NO synthesis, restored the hypotension.

Anaphylaxis↗

PubMed1994

Bivalvation with bridging for common atrioventricular valve regurgitation in right isomerism.

A child with regurgitation in the common atrioventricular valve associated with complex heart disease underwent bivalvation with bridging for common atrioventricular valve regurgitation and arterial-pulmonary shunt for low pulmonary blood flow. Postoperative cardiac catheterization and color Doppler echocardiography revealed elimination of atrioventricular valve regurgitation and ventricular enlargement, reflecting an increase in pulmonary artery blood flow. We describe the concept and technique of bivalvation with bridging for common atrioventricular valve regurgitation.

Child↗

PubMed1994

Vestibulo-ocular reflex abnormality in Vogt-Koyanagi-Harada syndrome.

The eye movements of 15 patients with Vogt-Koyanagi-Harada (VKH) syndrome were analysed. Transient dizziness occurred in 60% of the patients. Eight patients (53%) exhibited horizontal jerk nystagmus that was completely inhibited by visual fixation. Eight cases (53%) exhibited the elevation of vestibulo-ocular reflex (VOR) gain in darkness. Six of the patients with nystagmus had defective smooth pursuit movements with reduced gain on the side ipsilateral to the nystagmus. Saccadic and optokinetic eye movements were intact, and visual vestibular interaction was also normal. Impaired eye movements in VKH syndrome may be caused by asymmetry of the vestibular function secondary to the labyrinthine inflammation.

Adolescent↗

PubMed1994

Effect of 20-methylcholanthrene on the development of atherosclerosis in LAP quails.

We studied the effect of 20-methylcholanthrene, a carcinogen, on atherosclerosis in the ascending aorta and brachiocephalic arteries of hyperlipidemic and atherosclerosis-prone (LAP) quail. A total of 66 quails were divided into 6 groups and fed the following diets: Group I, basal; Group II, basal+low dose of carcinogen; Group III, basal + high dose of carcinogen; Group IV, basal + 0.2% cholesterol; Group V, basal + 0.2% cholesterol + low dose of carcinogen; and Group VI, basal + 0.2% of cholesterol + high dose of carcinogen. The carcinogen was dissolved in corn oil at 2 mg/ml and 4 mg/ml as low and high doses respectively, and was given orally twice weekly. Marked elevation of the serum cholesterol level and significant lipid-rich aortic lesions were observed in all the cholesterol-fed groups after 12 weeks. Although the serum cholesterol level in Group VI was lower than that in Group IV, the severity of the atherosclerotic lesion was greater in the former than in the latter. An immunohistochemical study showed a positive reaction of DBA, PHA and OKM-1 with the lipid-containing cells of aortic intimal lesions.

Animals↗

PubMed1994

[A successful case of repeated prosthetic valve re-replacement for somatic growth in childhood].

The patient who had had systemic atrio-ventricular valve replacement with Björk-Shiley 19 M at the age of 4 years was treated successfully with repeated re-replacement with St. Jude Medical 23M and St. Jude Medical 27M at the age of 8 years and 16 years respectively, because of his somatic growth. Two size larger valve was easily replaced at each operation. The original disease of this patient was corrected transposition of the great arteries with ventricular septal defect and regurgitation of the left atrio-ventricular valve caused by Ebstain anomaly and severe pulmonary hypertension. This case revealed that the annulus of the atrio-ventricular valve would grow even when fixed to the prosthetic valve sawing ring, thereby permitting the use of a larger-sized valve at the time of second and third prosthetic valve re-replacement.

Adolescent↗

PubMed1994

[Evaluation of bunazosin hydrochloride with a model of ocular circulation disturbance induced by endothelin-1].

We studied the effect of bunazosin hydrochloride, a selective alpha-1 blocker under development as an antiglaucomatous drug, on the circulation of the optic nerve head (ONH) in normal and endothelin-1 treated albino rabbit eyes. The effect was investigated by measurement of the capillary blood flow in the ONH, using a hydrogen gas clearance flowmeter (for 5 hours). The relative caliber of the retinal artery (the caliber of the retinal artery at the edge of the ONH/that of the ONH) was also measured, using fundus photography. Administration of bunazosin hydrochloride had no significant effect on the capillary blood flow in the ONH in normal eyes, but it inhibited the decrease of blood flow for at least 5 hours in the endothelin-1 treated eyes. The relative caliber of the retinal artery decreased in the endothelin-1 treated eyes (maximum at 5 hours), but previous administration of bunazosin hydrochloride inhibited the decrease. Thus, Bunazosin hydrochloride inhibits the disturbance of ONH circulation induced by endothelin-1 and promises to be useful also with regard to the ocular circulation.

Adrenergic alpha-Antagonists↗

PubMed1994

Serum-free culture of rat keratinocytes.

Procedures for the serum-free culture of rat keratinocytes have been established. Basal cells prepared from epidermis of newborn rat were stored in liquid nitrogen and used for primary culture. Among the available media, MCDB 153, developed originally for human keratinocyte (HK) culture, was the best for the development of serum-free formulation. To grow rat keratinocytes, bovine serum albumin was arbitrarily substituted for the macromolecule supplements needed for HK culture, i.e. fetal bovine serum protein or bovine pituitary extract. Qualitative and quantitative adjustment of supplements was thereafter made to support rapid cell growth. Satisfactory cell growth was achieved in the optimized medium of MCDB 153 supplemented with growth factors and amino acids: insulin (10 micrograms/ml), hydrocortisone (0.1 microgram/ml), epidermal growth factor (25 ng/ml), calcium chloride (0.2 mM), histidine (0.23 mM), isoleucine (0.05 mM), tryptophane (0.015 mM), threonine (1.25 mM), tyrosine (0.031 mM), alanine (4.08 mM), and albumin (2 mg/ml). This optimized culture system was superior to the original HK culture condition for rapid growth of rat keratinocytes. Under our condition, cells grew as a monolayer, becoming confluent, but without stratification, and were passaged 2 to 3 times without any changes in morphology. The serum-free formulation allows us to control more accurately the concentrations of biomolecules in the medium including lipids and hormones, and therefore will be suitable for the study focusing on lipid metabolism or hormonal regulation of rat keratinocytes.

Amino Acids, Essential↗

PubMed1993

Lipoprotein and apoprotein profile of Japanese quail.

The present study delineated the lipoprotein and apoprotein distribution in Japanese quail. Quail lipoprotein was composed of three fractions: VLDL, d < 1.020; LDL, 1.020 < d < 1.081; HDL, 1.081 < d < 1.210. When animals were fed the cholesterol-free diet, HDL was the predominant form, LDL intermediate, VLDL and chylomicron were smallest in amount. Feeding of cholesterol induced a marked change in the lipoprotein profile: VLDL or chylomicron predominated over HDL and LDL. An apoprotein of 26 kD (molecular weight) was the major protein moiety comprising more than 50% of total apoprotein in the entire density range of lipoprotein class. Amino acid composition of 26 kD protein was similar to hen, rat and human apo A-I. N-Terminal 36 amino acid sequence of 26 kD protein showed 92% homology to chicken apo A-I and 11% homology to human apo A-1. The 26 kD protein did not react with the antibody raised against human apo A-I. These observation showed that the 26 kD protein was partially identical to apo A-I.

Amino Acid Sequence↗

PubMed1993

Organization of the genes encoding chalcone synthase in Pisum sativum.

To analyze the regulation of defense-related genes by signal molecules produced by phytopathogens, we isolated genes that encode chalcone synthase (CHS) in Pisum sativum. We have obtained seven independent genomic clones that contain at least seven classes of CHS genes, identified by the hybridization analysis to CHS cDNA and by the restriction mapping analysis. Two of the genomic clones (clone 5 and 6) each contain two CHS genes in a tandem repeat. The nucleotide sequence analysis of CHS genomic clone 5 revealed that PsCHS1 and PsCHS2 were corresponding genes of the CHS cDNA clones, pCC6 and pCC2, respectively, as reported earlier. Both genes are interrupted by a single intron of 88 nucleotides with identical sequences, although exonic sequences and 5'-flanking sequences are divergent. Nucleotide sequences of the introns in five other classes of CHS genes showed that three classes had an intron of 87 nt with a striking homology to each other, but that the intron of the other two classes of CHS genes showed heterogeneity both in size and nucleotide sequence. 5'-upstream regions of PsCHS1 and PsCHS2 did not show sequence homology except the 31 bp identical sequence that contains the CCTACC motif resembling the box-1 sequence. Both PsCHS1 and PsCHS2 genes are shown to be induced by fungal elicitor by a primer extension analysis and a transient transformation analysis using pea protoplasts prepared from suspension cultured-cells.

Acyltransferases↗

PubMed1993

Fatty acid and lipid composition in vitro and in vivo of rat epidermis.

1. Fatty acid and lipid compositions of cultured rat keratinocytes were compared with those of intact epidermis prepared from newborn and adult rats. 2. The uniqueness of the lipid profile of cultured cell manifested itself in the accumulation of a novel lipid which co-migrated with monoalkyldiacylglyceride on thin-layer chromatography. 3. Concentration of the branched-chain fatty acid was specifically high in the cholesterol ester fraction of the intact cell, and was decreased by cultivation under submerged conditions.

Aging↗

PubMed1993

Semilunar valve replacement with a cylindrical valve.

A cylindrical valve was designed to prevent regurgitation of the semilunar valve. The valve is made of a sheet of polytetrafluoroethylene (PTFE) or porcine pericardium, and has three cusps and three commissures. The diameter of the valve is equal to the height of the cusps. We have used these valves in pulmonary stenosis after Jatene's operation and total correction of tetralogy of Fallot, and for truncal valve regurgitation. Regurgitation was trivial on color Doppler echocardiography in all cases. Advantages in comparison with the implantation of commercially available artificial valves include the ability to insert a larger size and no compression of the valve ring when closing the sternum. Outflow tract obstruction does not occur even when the valve is implanted in a small infant. In the present report, we describe this simple technique.

Animals↗

PubMed1993

Inhibition of ATPase activity in pea plasma membranes by fungal suppressors from Mycosphaerella pinodes and their peptide moieties.

The effects of two suppressors of the defense reactions of host plants, which had been purified from the pea pathogen Mycosphaerella pinodes, as well as the effects of peptide moieties, on the ATPase activity in pea plasma membranes were examined in vitro. One of the suppressors, Supprescin B, inhibited the ATPase activity in a non-competitive manner, but the other suppressor, Supprescin A, did not. Supprescin A was observed to reduce the inhibitory effect of Supprescin B. A tripeptide, Ser-Ser-Gly, and a hexapeptide, Ser-Ser-Gly-Asp-Glu-Thr, which were the respective peptide moieties of Supprescin A and B, inhibited the ATPase activity in a competitive manner. Supprescin B and fragments of the hexapeptide, such as Asp-Glu-Thr and Gly-Asp-Glu, inhibited not only the ATPase activity but also the acid phosphatase activity of plasma membranes in vitro. These results indicate that the acidic amino-acid residues of the "Asp-Glu" moiety seem to act as inhibitors of the phosphatase activity. Thus, the peptide moiety of Supprescin B consists of at least two functional elements.

Acid Phosphatase↗

PubMed1993

[A case of chronic progressive external ophthalmoplegia with pituitary hypothyroidism].

We report a case of chronic progressive external ophthalmoplegia with pituitary hypothyroidism. This patient had complained of hearing-loss at the age of fourteen and loss of body weight at fifteen. She was examined by otorhinolaryngologists at large hospitals yearly over a period of 5-6 years, but hearing-loss remained unknown. As her ophthalmoplegia progressed (as is evident from family photographs from the age of sixteen onward), with hindsight it should have been recognized. When examined on October 11, 1991, she complained of ptosis, speech disturbance and dysphagia at the age of thirty-four. Neurological examination revealed limitation of ocular movement, bilateral ophthalmoplegia, facial muscle atrophy, and weak gag reflex. She showed muscle atrophy in her neck including both sternocleidomastoid, major and minor rhomboid, girdle and distal parts of upper and lower extremities. Muscle biopsy of her biceps demonstrated ragged-red fibers, cytochrome c oxidase (CCO) deficient fibers and deletion of mitochondrial DNA. A plain CT scan revealed bilateral periventricular lucency, and a brain MR image showed a normal sized pituitary gland but diffuse high-signal intensities in the both periventricular white matter with proton density weighted and T2-weighted axial MR image. And also her electroencephalogram showed diffuse 7 Hz slow waves in all areas and increased slow waves by hyperventilation, and all waves from I to V of the auditory brain stem response disappeared. The effect of TRH on serum TSH secretion was not evident in this patient. This case was ascertained to be chronic progressive external ophthalmoplegia with pituitary hypothyroid function.

Adult↗

PubMed1993

[Successful surgical management of postinfarction left ventricular free wall rupture in a case of systemic lupus erythematosus].

A 58-year-old woman of postinfarction left ventricular free wall rupture (LVFWR) was surgically treated with good results. She had been treated with Prednisolon for 15 years with the diagnosis of systemic lupus erythematosus. The rupture was noted six hours after the onset of myocardial infarction and she was taken to the emergent surgical intervention. During the operation, active bleeding was found in the higher anterior wall of the left ventricle and a Dacron graft was sutured to cover the infarcted area. The postoperative course was uneventful. This report seemed to be the first one of the successful surgical management of LVFWR in the course of the treatment for SLE in the literature.

Emergencies↗

PubMed1993

[Effects of intravitreal injection of endothelin on the visual system].

Endothelin, a novel, potent, and long-acting vasoconstrictor peptide, is thought to regulate retinal circulation and its autoregulation. A disturbance in the regulation of endothelin production might contribute to the pathogenesis of retinochoroidal or optic nerve diseases. We examined the effects of endothelin on the retina and the optic nerve using the electroretinogram (ERG) and visual evoked potential (VEP). Six male albino rabbits underwent intravitreal injection of 0.1 ml (10(-5) mol/l) endothelin-1 in the right eye. Six other male albino rabbits, which were injected intravitreally with 0.1 ml of Opeguard-MA in the right eye, were used as controls. Endothelin-1 caused marked constriction of retinal vessels and pallor of the optic nerve head. These findings persisted for 10 days after endothelin-1 injection. The amplitude of the b-wave and the latency of the oscillatory potential in the ERG were not significantly different from those in controls. On the other hand, prolongation of the VEP-N1 latency was observed for 14 days after the injection. These results indicate that endothelin acts on the circulation of the optic nerve head rather than that of the retina, and that effects persist for a relatively long period.

Animals↗