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Biomedical subjects

H Oku

Publications and source records attributed to H Oku.

At least 127 records · Page 7Linked to original sources
PubMed1993

[Effect of endothelin-1 on ocular circulation].

Endothelin (ET)-1, a potent vasoconstrictor which was discovered recently, might be involved in the regulation of ocular circulation. In this paper, we studied the effects of ET-1 on capillary blood flow of the optic nerve head and choroid in rabbits, using a hydrogen gas clearance flowmeter. Intravitreal injection of 0.1 ml of ET-1 at 10(-5) M and 10(-6) M caused a significant decrease in blood flow, which in the optic nerve head continued more than 3 hours, but in the choroid recovered at 3 hours after the injection (maximum decrease occurred at 75 minutes and at 30-60 minutes, respectively). Intraocular pressure was reduced as the time passed. Intravenous administration of 10(-10) mol/kg of ET-1 induced a reduction in blood flow, which in the optic nerve head continued more than 3 hours, but in the choroid recovered at 90 minutes after the administration. Intraocular pressure was reduced during 3 hours' observation. The decrease in blood flow in the optic nerve head was inhibited by previous administration of calcium antagonist (nicardipine), so the calcium channel was thought to be involved in this reaction.

Animals↗
PubMed1992

Age-related changes of the branched-chain fatty acid concentration in rat skin surface lipid.

1. Age-related change of the branched-chain fatty acid distribution in rat skin surface lipid was studied for 24 months. 2. The proportion of even carbon number iso-acid increased from infancy to month 5 and thereafter decreased with advancing age toward senescence. 3. Concentration of odd carbon number iso-acid depicted a similar shape of time course, but with a lesser magnitude and a peak value at month 1. 4. Anteiso- fatty acid reached the plateau level at month 5 and remained roughly constant through maturity to senescence.

Aging↗
PubMed1992

Characterization of carbohydrate-binding specificity of concanavalin A by competitive binding of pyridylamino sugar chains.

Carbohydrate-binding specificity of Con A was characterized by competitive binding studies of pyridylamino (PA) sugar chains. PA-derivatives of 17 oligomannose-type sugar chains, Man1-9GlcNAc2-PA, and those of three complex-type sugar chains were used as ligands. The ratios of bound and free sugar concentrations, [LS]/[S], were determined by means of microequilibrium dialysis followed by high performance liquid chromatography as already reported [Mega, T. & Hase, S. (1991) J. Biochem. 109, 600-603]. The association constant, Ka, was calculated from [LS]/[S] of a sugar chain and that of a standard sugar chain by using the equation Ka = Ka0 x ([S0]/[LS0]) x ([LS]/[S]), where Ka0, [S0], and [LS0] are the association constant, and the free and bound ligand concentrations of the standard sugar chain, respectively. This calculation was effective for the determination of Ka of ligands with similar affinities to the standard sugar chain. The carbohydrate structures with highest affinity for Con A among those tested were found to be: [formula: see text]

Amino Sugars↗
PubMed1992

Extensive specifically localized myocardial calcium deposition in a hemodialysis patient.

A 51-year-old female who was hospitalized for evaluation of frequent episodes of hypotension, died unexpectedly. At autopsy, there were many fine, white granular deposits in the myocardium, which were more prominent in the subepicardium of the left ventricle than in the subendocardium. Pathologic calcification is sometimes seen in chronic hemodialysis patients and in some organs the sites of calcium deposition are quite specific. There have been few reports concerning the pattern of calcium deposition in the myocardium and, to our knowledge, the reason for this characteristic distribution is unknown. However it may relate to hydrogen ion concentration in the myocardium.

Calcinosis↗
PubMed1992

[Continuous distribution of ventilation-perfusion ratios following lung denervation in dogs by means of inert gas elimination method].

Pulmonary branches of the vagus nerve and sympathetic nerve-chain are severed frequently in thoracic surgery. In this investigation, respiratory function, this transection influence on, was studied, experimentally. Then, denervation of the left lung carried out in mongrel dogs. And distribution of ventilation-perfusion ratio actually present in the lung was measured by multiple inert gases elimination method. In dogs with denervated one side lungs, imbalance of distribution of ventilation-perfusion ratio existed, and it mean that there were areas of high VA/Q in distribution of ventilation. However, there was still no shunt and distribution of blood flow was no dispersion. From the it seems reasonable to infer that blood flow in pulmonary vessel diminished by pulmonary denervation. But arterial blood gas analysis showed normal degree. Accordingly pulmonary gas exchange should not be disturbed to high degree by imbalance of VA/Q distribution due to the denervation.

Animals↗
PubMed1992

[Apico-aortic conduit repair for the subaortic stenosis in the long-term period after correction of Taussig-Bing malformation].

Apico-abdominal-aortic bypass operation was successfully performed for the left ventricular outflow tract obstruction 17 years after correction of Tausig-Bing malformation. At the age of 14 months old, a 18-year-old patient underwent total correction of Taussig-Bing malformation according to Kawashima's intraventricular re-routing. The right ventricular hemodynamics were normal throughout, however, systolic ejection murmur due to aortic stenosis appeared 3 years after repair. Seventeen years postoperatively, marked aortic valve and subaortic obstruction was detected corresponding with the internal conduit made from the duplicated autopericardial baffle. A composite graft containing 23A-SJM valve was interposed between the left ventricular apex and infrarenal abdominal aorta. After the bypass operation, thickness of the posterior wall of the left ventricle and interventricular septum was significantly reduced and symptoms were remarkably improved. The present paper is concerned with the subaortic stenosis after repair of Taussig-Bing malformation and technique of apico-aortic bypass operation.

Adolescent↗
PubMed1992

[A pupillographical study on the effects of cataract surgery on the contralateral eye].

In order to estimate the effect of cataract surgery on the contralateral eye, we examined pupillary light reflex and performed laser flare-cell measurement. The subjects were nine patients who underwent extracapsular cataract extraction (ECCE) and fourteen patients who underwent ECCE with intraocular lens implantation. Pupillary light reflexes of the contralateral eyes were examined using a computerized videopupillogram (HTV C-301). Aqueous cells and flare of both eyes were measured by a laser flare-cell meter (KOWA FC 100). The author performed five successive measurements before and 1, 3 days, 1, 2 weeks and 1, 2, 3 months after surgery and statistically estimated the consensual effect of cataract surgery. As a result of contralateral cataract surgery, pupils became significantly miotic from the first postoperative day for more than 3 months without any alteration of other parameters of light reflex. On the contrary aqueous cells and flare significantly raised from the first postoperative day and disappeared within 3 months. Consensual miosis was considered to be sensitive indicator of postoperative inflammation of cataract surgery as well as contralateral increase of aqueous cells and flare.

Adult↗
PubMed1991

Plasma levels of platelet-derived growth factor in normal subjects and patients with ischemic heart disease.

Plasma levels of platelet-derived growth factor (PDGF) were measured in 24 normal control subjects, 31 patients with stable angina pectoris, 25 patients with unstable angina pectoris, and 31 patients with acute myocardial infarction (AMI) by a sensitive direct radioimmunoassay. The plasma PDGF level in normal control subjects was 273 +/- 25 pg/ml; there was no significant correlation between the plasma PDGF level and age. Plasma PDGF levels in patients with unstable angina pectoris and acute myocardial infarction were significantly lower than those in normal control subjects and patients with stable angina pectoris (p less than 0.05). In patients with acute myocardial infarction the plasma PDGF level in the chronic phase was significantly higher than that in the acute phase (p less than 0.05). These observations raise the possibility that PDGF is involved in the pathophysiology of ischemic heart disease.

Adult↗
PubMed1991

Purification and characterization of neutral alpha-mannosidase that is activated by Co2+ from Japanese quail oviduct.

An alpha-mannosidase was purified from the magnum section of Japanese quail oviduct by ammonium sulfate precipitation, DEAE-Sephacel chromatography, Sephacryl S-300 chromatography, mannan-Sepharose 4B chromatography, and hydroxyapatite chromatography. The purified alpha-mannosidase (referred to as neutral alpha-mannosidase) showed a single band on polyacrylamide gel with or without sodium dodecyl sulfate. Its molecular weight was found to be 330,000 by gel chromatography. Neutral alpha-mannosidase hydrolyzed p-nitrophenyl alpha-D-mannopyranoside and the pyridylamino derivative of Man alpha 1-6(Man alpha 1-3)Man alpha 1-6(Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4GlcNAc (Km value was 3 mM). Mannosyl alpha 1-2 linkages in the pyridylamino derivative of Man alpha 1-2 Man alpha 1-6(Man alpha 1-2Man alpha 1-3)Man alpha 1-6(Man alpha 1-2Man alpha 1-2Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4GlcNAc were hardly hydrolyzed. Its optimum pH was found to be 7.0. The activity of the enzyme was activated by CO2+, and was potently inhibited by Cu2+, Hg2+, swainsonine, and 1-deoxymannojirimycin.

Animals↗
PubMed1991

Studies on the substrate specificity of neutral alpha-mannosidase purified from Japanese quail oviduct by using sugar chains from glycoproteins.

The substrate specificity of neutral alpha-mannosidase purified from Japanese quail oviduct [Oku, H., Hase, S., & Ikenaka, T. (1991) J. Biochem. 110, 29-34] was analyzed by using 21 oligomannose-type sugar chains. The enzyme activated with Co2+ hydrolyzed the Man alpha 1-3 and Man alpha 1-6 bonds from the non-reducing termini of Man alpha 1-6(Man alpha 1-3)Man alpha 1-6(Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4GlcNAc (M5A), but hardly hydrolyzed the Man alpha 1-2 bonds of Man9GlcNAc2. The hydrolysis rate decreased as the reducing end of substrates became more bulky: the hydrolysis rate for the pyridylamino (PA) derivative of M5A as to that of M5A was 0.8; the values for M5A-Asn and Taka-amylase A having a M5A sugar chain being 0.5 and 0.04, respectively. The end product was Man beta 1-4GlcNAc2. For the substrates with the GlcNAc structure at their reducing ends (Man5GlcNAc, Man6GlcNAc and Man9GlcNAc), the hydrolysis rate was remarkably increased: Man5GlcNAc was hydrolyzed 16 times faster than M5A, and Man2GlcNAc 40 times faster than Man9GlcNAc2. The enzyme did not hydrolyze Man alpha 1-2 residue(s) linked to Man alpha 1-3Man beta 1-4GlcNAc. The end products were as follows: [formula; see text] These results suggest that oligomannose-type sugar chains with the GlcNAc structure at their reducing ends seem to be native substrates for neutral alpha-mannosidase and the enzyme seems to hydrolyze endo-beta-N-acetylgucosaminidase digests of oligomannose-type sugar chains in the cytosol.

Animals↗
PubMed1991

Pheochromocytoma with electrocardiographic change mimicking angina pectoris, and cyclic change in direct arterial pressure--a case report.

A forty-two-year-old man was admitted because of chest pain. Electrocardiograms at admission showed horizontal ST depression in leads, II, III, aVF, V4, V5, and V6. Direct blood pressure monitoring revealed cyclic change between 160/100 mmHg and 70/50 mmHg and heart rate between 80/sec and 120/sec at fifteen minute intervals. The plasma norepinephrine and epinephrine concentrations were elevated during the episodes of hypertension. Pheochromocytoma was found in the right adrenal gland. These cyclic changes in blood pressure and heart rate are an aid for diagnosis.

Adrenal Gland Neoplasms↗
PubMed1991

Two-dimensional and Doppler echocardiographic findings in a case of subaortic "fibrous sac".

We described a 37-year-old man with a subaortic "fibrous sac", admitted for congestive heart failure. On 2-dimensional echocardiography a saccular structure was seen to extend from the left coronary cusp of the aortic valve to the outflow tract of the left ventricle. By color Doppler imaging, a grade 3 aortic regurgitation was recognized. Aortic regurgitant flow was recorded from the left coronary cusp to the saccular lesion. When congestive heart failure became exacerbated, the repeat examination showed the regurgitant flow passing through the perforated bottom of this lesion and reaching the left ventricular cavity. On microscopic examination of the excised valve, capillary proliferation and inflammatory changes were recognized near the annular region of the left coronary cusp. The edge of the valve leaflet and the other 2 cusps were intact. It is likely that our patient had a mycotic aneurysm near the aortic ring. We speculate that aortic regurgitation followed inflammation. It dilated the left ventricular cavity and contributed to congestive heart failure. Inflammation also weakened the tissue near the annulus, causing it to protrude into the subaortic region thus forming a small aneurysm. It may have grown to become a large saccular structure under high aortic pressure. That is, it became a "giant" endocardial pocket with inflammatory process. Finally, the rupture of this sac caused a massive aortic regurgitation, exacerbating congestive heart failure.

Adult↗
PubMed1991

Assessment of superior vena caval blood flow velocity in ischemic heart disease.

In order to evaluate the right atrial function in patients with ischemic heart-disease, we studied the superior vena caval blood flow velocity using pulsed Doppler echocardiography. The subjects included 31 patients with anteroseptal infarction (ANT), 23 with inferior or inferoposterior infarction (INF + POS), 27 with effort angina pectoris (EAP) and 15 with vasospastic angina pectoris (VAP). The systolic peak flow velocity (PFVs) was significantly reduced only in INF + POS compared with those in ANT, EAP and VAP (36.8 +/- 1.8 cm/sec vs 46.9 +/- 2.1 cm/sec, 46.4 +/- 2.1 cm/sec and 42.6 +/- 1.9 cm/sec, p less than 0.05, respectively). No significant difference in diastolic peak flow velocity (PFVd) was found between the 4 groups. PFVs/PFVd was significantly reduced only in INF + POS compared with those in ANT, EAP, and VAP (1.39 +/- 0.05 vs. 1.75 +/- 0.08, 1.76 +/- 0.09, and 1.62 +/- 0.09, p less than 0.05, respectively). These results suggested that INF + POS caused impairment of the right atrial reservoir function.

Analysis of Variance↗
PubMed1991

Correlation between serum concentrations of the branched chain amino- and alpha-keto-acid and the distribution of the branched-chain fatty acids on rat skin surface.

This study described the relationship between the concentration of the branched-chain fatty acid (BCFA) in rat skin surface lipid and the serum level of the branched-chain amino acid (BCAA) and branched-chain alpha-keto acid (BCKA). The concentrations of the BCFAs in the monoester fraction of the skin surface lipid, and BCAAs and BCKAs in the serum were analyzed in rats fed varying amounts of protein (0 to 40%) and different types of BCAAs (3%) for 2 weeks. The serum concentrations of BCAA were proportional to the protein level by day 10 of the feeding period. This dose response was not sustained by day 14 at the end of the feeding. Protein level dependence was not so evident in the concentration of BCKA. The concentrations of BCFA, even carbon number iso-acid in particular, increased in linear proportion to protein intake in the skin surface lipid. Supplementation of valine and isoleucine to the diet at a 3% level specifically raised the concentration of the respective BCAA and corresponding BCKA in serum, and related BCFA in the skin surface lipid. Addition of leucine, however, did not affect the related BCFA concentration in spite of elevated concentration of leucine and its alpha-keto acid. A good linear correlation between the average concentration of the substrates in the circulation and the concentrations of the product BCFA on the skin surface was thus obtained for valine, isoleucine and their respective alpha-keto acid. This relationship did not appear to hold up for leucine and its alpha-keto acid.

Amino Acids, Branched-Chain↗
PubMed1991

[Cyanide with vitamin B12 deficiency as the cause of experimental tobacco amblyopia].

The visual toxicity of tobacco smoke was studied and demyelination change of retrobulbar portion of the rat's optic nerve with an elongation of a peak latency time of visual evoked potentials (VEP) was demonstrated. Cyanide detoxication incapacity and deficiency of vitamin B12 (B12) have been considered as possible causes of tobacco amblyopia. In order to elucidate an influence of cyanide poisoning and B12 deficiency on the visual system, 12 male Wistar rats were subjected to 5 hour's daily inhalation of cyanide gas for 52 weeks, the concentration of which was adjusted to that of tobacco smoke. Six rats of these 12 were fed with a lacking B12 diet. Another 12 male Wistar rats were controls which did not undergo inhalation of cyanide gas, and half of them were fed a diet without B12. In 2 out of 6 rats with cyanide and inhalation and B12 deficiency, demyelination change could be recognized in the central portion of the retrobulbar optic nerve. The histological change was segmental and significant elongation of the peak latency time of VEP was not recognized. Cyanide gas inhalation at a low concentration was proved to be harmful to the optic nerve under the condition of B12 deficiency, but other toxic elements such as nicotine and carbon monoxide may be important factors to cause the more severe changes of the optic nerve with an abnormal VEP response recognized in the experimental tobacco amblyopia.

Amblyopia↗
PubMed1990

Separation of oligomannose-type sugar chains having one to five mannose residues by high-performance liquid chromatography as their pyridylamino derivatives.

Ten oligomannose-type sugar chains (ManGlcNAc2-Man5GlcNAc2) were prepared from various glycoproteins and fluorescence labeled with 2-aminopyridine. The fluorescent pyridylamino (PA)-sugar chains were first separated into five fractions according to their molecular sizes by HPLC on a TSK gel Amide-80 column. Each fraction was then separated into the component PA-sugar chains by reversed-phase HPLC on a Capcell Pak C18 column according to their chemical structures. The method is useful for studying the substrate specificities of alpha-mannosidases with Man5GlcNAc2-PA as a substrate.

Aminopyridines↗