Search PubMed⌕ Search

Biomedical subjects

N Oshima

Publications and source records attributed to N Oshima.

At least 37 records · Page 2Linked to original sources
PubMed1997

Improvement in baroreflex function by an oral angiotensin receptor antagonist in rats with myocardial infarction.

Impaired baroreflex function is a factor responsible for poor prognosis in myocardial infarction patients. Using logistic function curves, we calculated the maximal gain of the baroreflex control of renal sympathetic nerve activity (RSNA) and heart rate in conscious Wistar-Kyoto and spontaneously hypertensive rats whose left anterior descending artery had been ligated 4 weeks earlier. We further investigated whether 3-week oral treatment with the angiotensin II type 1 receptor antagonist TCV-116 would improve the baroreflex in rats with myocardial infarction. The maximal gain of the mean arterial pressure-RSNA relation in spontaneously hypertensive rats with myocardial infarction and treated with vehicle (1.7 +/- 0.1% control per mm Hg) was smaller than the gain in sham-operated hypertensive rats (2.3 +/- 0.1% control per mm Hg). After 3-week oral treatment with TCV-116, the maximal gain of the arterial pressure-RSNA relation in hypertensive rats with myocardial infarction was 2.3 +/- 0.1% control per mm Hg and significantly greater than the gain in infarcted and vehicle-treated hypertensive rats. In hypertensive rats, the maximal gain of the arterial pressure-heart rate relation of infarcted and TCV-116-treated rats was larger than in infarcted and vehicle-treated rats but significantly smaller than in sham-operated rats. These results demonstrate that oral treatment with an angiotensin receptor antagonist is effective in restoring the impaired baroreflex caused by myocardial infarction and that endogenous angiotensin II is one of the critical factors involved in the impaired baroreflex in myocardial infarction.

Administration, Oral↗
PubMed1997

Interaction between endothelin and nitric oxide in sympathetic nerve modulation in hypertensive rats.

To test the hypothesis that endothelin (ET) and nitric oxide (NO) interact in modulating the sympathetic nervous system in conscious rats, as they do in the endothelium, mean arterial pressure (MAP), heart rate, and renal sympathetic nerve activity (RSNA) were recorded in Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) given losartan and compared before and during intravenous infusion of an NO synthase inhibitor, L-NMMA (0.25 mg/kg/min). The slope of the relation between RSNA and MAP to blood pressure reduction was increased in the presence of L-NMMA (from 0.6 +/- 0.1 to 2.8 +/- 0.2), suggesting that endogenous NO suppresses the reflex increase in RSNA. Since NO inhibits ET production in the endothelium, we speculated that the increase in MAP-RSNA slope was due partly to an unmasking of ET, and thus recorded MAP, heart rate, and RSNA during intravenous infusions of both L-NMMA and the ET-type-A-receptor antagonist BQ-485 (0.10 mg/kg/min). The slope decreased significantly in SHR when BQ-485 was added (1.5 +/- 0.2), but not in WKY, implying that unmasked ET enhanced the sympathetic increase via ETA receptors in hypertensive rats. An ETB-receptor antagonist potentiated the sympathetic response only in WKY rats. These results suggest that NO suppressed the reflex increase in RSNA to blood pressure reduction, while ET uncovered by L-NMMA enhanced the sympatho-activation, indicating an interaction between ET and NO in modulating the sympathetic nervous system in conscious hypertensive animals in vivo. In contrast, the interaction was not observed in normotensive rats.

Animals↗
PubMed1997

[Combined erythropoietin and aprotinin use for blood conservation in elderly coronary bypass patients].

Age is one of the predictors of homologous blood transfusion (HBT) in cardiac surgery. To avoid HBT, we have employed pharmacological blood conservation techniques such as the administration of erythropoietin (EPO) in conjunction with autologous blood donation (ABD) and the administration of aprotinin in prime volume. The effectiveness of these methods was evaluted in elderly patients who underwent coronary artery bypass grafting (CABG). Seventy-nine elective coronary bypass patients were classified into two groups by age: group A (> or = 70 y.o., n = 29) and group B (< 70 y.o., n = 46). EPO (24,000 U) was administered once a week subcutaneously starting 3 weeks before the operation. ABDs were carried out as long as the blood hemoglobin levels were above 10.5 g/dl. A significant increase of preoperative blood hemoglobin was observed in both groups. Although the blood hemoglobin levels at the beginning of ABD were lower in group A than in group B, the mean amount of predonated blood per patients was similar in both groups. In 79.3% of group A and in 84.8% of group B, HBT was not required: furthermore, in the prodonated patients, this no-HBT rate could be increased to 84.0% of group A and to 88.1% of group B. These results suggest that CABG in elderly patients can be performed safely without HBT when pharmacological blood conservation techniques are employed.

Age Factors↗
PubMed1995

Changes in adrenergic innervation to chromatophores during prolonged background adaptation in the medaka, Oryzias latipes.

The pattern of adrenergic innervation to scale chromatophores of the wild-type medaka, Oryzias latipes, was examined by autoradiography with 3H-norepinephrine and found for the first time to be changed reversibly during prolonged background adaptation. In scales of the medaka, which was adapted to a black background for 10-15 days, a great number of melanophores and dense networks of varicose fibers were observed: many fibers built up a radial plexus around each melanophore. However, the dense distribution of varicose fibers disappeared with a decrease in the number of melanophores during long-term adaptation to a white background. As to the changes in the innervation pattern to amelanotic melanophores of the medaka, orange-red variety, a similar result was obtained. Although the increase in the number of leucophores was observed in the medaka adapted to a white background, no exact plexuses of labeled fibers were confirmed around leucophores. From these results, it is concluded that the density of chromatic nerve fibers changes in parallel with the variation of the number of melanophores during prolonged background adaptation.

Acclimatization↗
PubMed1995

[Mitral obstruction due to infective endocarditis: a case report].

Acute valvular obstruction caused by vegetation is a rare complication infective endocarditis. To our knowledge, only 9 cases and an autopsy case by Roberts have been reported since 1967. A 46-year-old man admitted with a chief complaint of pyrexia for 2 months duration. Within 24 hours of admission, the patient noticed of increased shortness of breath. Physical examination and the chest X-ray confirmed the pulmonary edema. An echocardiogram revealed a huge echogenic mass that was adherent to the mitral leaflet and obstructed the orifice completely. Soon after the patient fell into cardiogenic shock, an emergency mitral valve replacement was undertaken. At operation, multiple verrucae arising from the entire mitral leaflet was seen to occlude the orifice. The vegetation was excised and replaced with a # 25 Omnicarbon prosthesis. Postoperatively, the patient developed multiple organ failure caused by cardiogenic and septic shock which responded well to intensive medical treatment consisting of hemodialysis and continuous arteriovenous hemofiltration. Angiographically, a mycotic aneurysm in the left radial artery was found on the 18th postoperative day. After extirpation of the infective focuses, the postoperative course had stabilized. Mitral obstruction due to infective endocarditis is a fatal disease. Prompt diagnosis with echocardiogram and an emergency surgery should be undertaken to save the patient.

Endocarditis, Bacterial↗
PubMed1994

[A case of unroofed coronary sinus with persistent left superior vena cava].

A 44-year-old female with left to right shunt and persistent left superior vena cava (PLSVC) suspected of unroofed coronary sinus defect with patent right SVC and innominate vein was treated surgically. PLSVC was ligated and coronary sinus ostium was closed with a EPTFE patch. Roof defect of coronary sinus was left open and allowed the coronary venous blood to drain into the left atrium. Patient recovered well and post-operative cardiac catheterization revealed no significant right to left shunt nor desaturation of arterial blood. In the correction of unroofed coronary sinus defect and PLSVC and no other intra-cardiac defect, ligation of PLSVC and closure of coronary sinus ostium was simple and effective, although it was not anatomically corrected.

Adult↗
PubMed1993

Effects of prolactins on the chromatophores of the tilapia, Oreochromis niloticus.

Using isolated scales and split-fin preparations of the tilapia Oreochromis niloticus, the effects of a pair of prolactins of the tilapia Oreochromis mossambicus (tPRL177 and tPRL188) and of ovine prolactin (oPRL) on chromatophores were studied in vitro. These peptides caused melanosome aggregation and dispersion of xanthosomes, especially in the split preparations. Their relative effectiveness was as follows: tPRL177 > oPRL > tPRL188. Moreover, tPRL177 at 100 nM induced a high level of pigment dispersion in cultured xanthophores and erythrophores, but tPRL188 at the same concentration did not have this effect. We also examined the responses of chromatophores to oPRL in primary cell culture and found that xanthophores and erythrophores respond to the peptide by pigment dispersion in a dose-dependent manner, whereas cultured melanophores showed little aggregation of pigment. In denervated melanophores in the split-fin preparations, tPRL177 failed to induce aggregation of pigment. From these results, it was concluded that prolactin affects brightly pigmented cells of the tilapia directly, but affects melanophores indirectly. Norepinephrine which might leak from varicosities of chromatic nerve fibers by virtue of the action of prolactin molecules may be responsible for melanosome aggregation.

Animals↗
PubMed1993

Circadian motile activity of erythrophores in the red abdominal skin of tetra fishes and its possible significance in chromatic adaptation.

The red abdominal skin of the neon tetra Paracheirodon innesi and the cardinal tetra P. axelrodi was found to blanch at night or in the dark. Melatonin added to the bathing medium caused blanching of the red skin. Microscopic observations of the erythrophores indicated that the erythrosomes aggregated in response to norepinephrine, melanin-concentrating hormone (MCH), and melatonin. Of these compounds, melatonin was the most effective. By contrast, many erythrophores were refractory to MCH. Alpha-melanophore-stimulating hormone, isoproterenol, adenosine, and ATP each caused dispersal of the pigment to some extent. Isoproterenol dispersed the pigment only when an alpha-adrenergic blocker, tolazoline, was present. It appears that the change in color of the abdominal skin is primarily due to increased secretion during the night of the pineal hormone melatonin, while other hormonal and nervous factors may modify the distribution of the pigment in the erythrophores.

Adaptation, Physiological↗
PubMed1993

[Primary chylopericardium: a case report].

A case of primary chylopericardium in a 54 year-old-man was reported. Despite 3 times of pericardiocentesis, the pericardial fluid accumulated rapidly. After the fenestration of pericardium, a small cannula was inserted for the thoracic ductgram which showed a clearly visible duct upward to the angulus venosus and an abnormal branch near the bifurcation of the trachea spilling some contrast material into the pericardial cavity. Ligation and division of the thoracic duct including an abnormal branch was performed from its entry to the thorax for a length of 13 cm upward. The postoperative course was uneventful and chest X-ray film taken 6 months after surgery showed no accumulation of chyle in the pericardium and pleural cavity.

Chyle↗
PubMed1990

[Effect of ulinastatin (UL) on renal function and lactic acidosis during open-heart surgery: comparison with aprotinin (Ap)].

Comparison was made on the renal function and lactic acidosis during cardiopulmonary bypass (CPB) between the group Ul (n = 15) and group Ap (n = 27). A 300,000 u, of ulinastatin was administered intravenously before CPB and 300,000 u, in the prime solution. A 300,000 u, of aprotinin was administered in the prime solution. Urine output during CPB was not significantly different, but the total dose of furosemide administered was less in group Ul and a significant difference (p less than 0.05) was observed in the free water clearance at CPB 1 hr. and 3 hr. postoperatively, -0.83 +/- 0.16 and -1.74 +/- 0.14 in group Ul and -0.43 +/- 0.10, -0.99 +/- 0.14 in group Ap, respectively. Arterial lactate increased as the perfusion time increased but the level at the end of CPB was significantly lower (p less than 0.05) in group Ul and the added 7% NaHCO3 to correct metabolic acidosis during CPB of 29.3 +/- 9.5 ml in group Ul was less than in group Ap of 82.2 +/- 15.2 ml (p less than 0.01). The result suggests the favourable effects of ulinastatin on the renal function and lactic acidosis during CPB.

Acidosis, Lactic↗
PubMed1990

[Left ventricular-right atrial communication following mitral valve replacement].

A case of an acquired left ventricular-right atrial communication complicating Omnicarbon replacement of a severe calcified mitral valve in the area of the posteromedial commissure is reported. The intricate relationships of the membranous atrioventricular septum to the mitral valve and the tricuspid valve predispose to the creation of an iatrogenic left ventricular-right atrial fistula when aggressive debridement of extensive valvular calcification is performed. Emphasis is placed on the diagnosis, and immediate surgical repair is advocated as soon as this complication is discovered.

Female↗
PubMed1990

[Two cases of perioperative coronary vasospasm following ASD closure and OMC].

Two cases of perioperative coronary spasm following ASD closure and OMC are reported. A 36-year-old female had been diagnosed of vasospastic angina and another 47-year-old female patient was diagnosed of effort angina for 99% stenosis of the right ventricular branch preoperatively. Both patients suffered from coronary vasospastic attack and ventricular fibrillation several times within 17 hours postoperatively. Although the coronary dissolution was obtained finally following aggressive cardiac massage, administration of spasmolytic agents, such as NTG, lidocaine, DBcAMP and the start of IABP, the resolution was stormy due to the hemodynamic derangement. To prevent the coronary spastic episode, it is suggested, for patients of possible coronary spasm, to avoid arousal stimulation and to administer spasmolytic agents prophylactically within the first postoperative day.

Adult↗
PubMed1990

[The surgical treatment of endomyocardial fibrosis of the left ventricle--the first surgical case report in Japan].

A 66-year-old man with an ECG finding of an elevation of R in leads V5-6 and a calcified space occupying lesion in the apex of the left ventricle on echocardiography admitted for the evaluation of recent onset of shortness of breath and palpitation on exertion. Cineangiography showed an obliteration and accumulation of RI activity in the apex of the left ventricle on TI-201 scintigraphy and a neoplasm of the heart was suspected. Resection of a tumor from apical incision followed by the left atrial approach necessitated the replacement of mitral valve and confirmed the diagnosis of endomyocardial fibrosis. Heart failure persisted and the expired 2 years after surgery due to the gastrointestinal infection. An experience suggested the resection of a mass from the left atrial approach is possible and recommended to prevent the occurrence and persistence of heart failure in case the diagnosis is established preoperatively.

Aged↗
PubMed1987

Use of a series of ompF-ompC chimeric proteins for locating antigenic determinants recognized by monoclonal antibodies against the ompC and ompF proteins of the Escherichia coli outer membrane.

A method is presented for the efficient location of antigenic determinants using a series of chimeric proteins. By means of in vivo homologous recombination between the ompC and ompF genes coding for OmpC and OmpF, homologous proteins of the Escherichia coli outer membrane, a series of ompF-ompC chimeric genes was constructed (Nogami, T., Mizuno, T., & Mizushima, S. (1985) J. Bacteriol. 164, 797-801, and this work). The OmpF-OmpC chimeric proteins expressed by these genes were successfully used to locate antigenic determinants recognized by monoclonal antibodies, which specifically react with either the OmpC or OmpF protein. Interaction between monoclonal antibodies and the chimeric proteins was examined by means of either enzyme-linked immunosorbent assay or immunoblot analysis. The antigenic determinants recognized by three anti-OmpC antibodies and one anti-OmpF antibody were thus located. Finally, the polypeptides covering these regions were chemically synthesized for two of them and then tested as to their reactivity with the antibodies. The peptides reacted with the corresponding antibodies when the former were chemically coupled with bovine serum albumin. Most of the monoclonal antibodies isolated in this work were highly specific to the unfolded monomer of the protein against which the antibody was raised. But they did not react with the trimer, the native form. These results are discussed in relation to the structures and functions of the OmpC and OmpF proteins. The use of a series of monoclonal antibodies for studying the mechanism of protein translocation across the cytoplasmic membrane is also discussed.

Antibodies, Bacterial↗
PubMed1987

Divisionistic generation of skin hue and the change of shade in the scalycheek damselfish, Pomacentrus lepidogenys.

In addition to melanophores and xanthophores, there existed two types of iridophore in the dermis of the scalycheek damselfish, Pomacentrus lepidogenys. There are dendritic iridophores which reflect white light-rays by Tyndall scattering, and the round or somewhat ellipsoidal iridophores which reflect rays with a relatively narrow spectral peak from blue to green through the non-ideal thin-film interference. Most of the dendritic iridophores were covered with xanthophores and were situated over melanophores, thus constituting a kind of chromatophore unit which produces a yellow or yellowish-green color. The characteristic yellowish-green hue of the integument results from a compound effect of small contributions by more elementary colors. During color changes of the skin, the position of the spectral peak does not shift. Unlike the iridophores of the blue damselfish, both types of iridophore of the scalycheek damselfish were found to be inactive. It appears, therefore, that the aggregation and dispersion of pigment within the melanophores is the primary mechanism responsible for the changes in color of this species.

Animals↗
PubMed1987

[Effect of dobutamine and diltiazem on the reperfused ischemic myocardium].

Twenty-two anesthetized open-chest mongrel dogs were studied to evaluate the effect of dobutamine, dobutamine and diltiazem on the ischemic-reperfused myocardium assessed by cardiac function, myocardial metabolism such as tissue ATP, Ca and water content and ultrastructure. The left anterior descending coronary artery was ligated for 40 minutes and then reperfused for 15 minutes. Experiments were divided into 3 groups by infusion of physical saline solution (C), dobutamine 5 micrograms/kg/m in (DOB) and dobutamine 5 micrograms/kg/min+diltiazem 0.1mg/kg bolus IV at the beginning of reperfusion and followed by continuous infusion with 30 micrograms/kg/min (DOB+D) during reperfusion period. DOB increased SAP and CI, however it also increased heart rate. CI, LVSWI and coronary blood flow in non ischemic area increased significantly in DOB+D than either C or DOB. Myocardial ATP in the ischemic endocardium was much more preserved in DOB and DOB+D than C. Myocardial Ca and water content were lower level in DOB+D, but not significantly different among 3 groups. Mitochondrial score by Sunamori's method in DOB+D was higher than that in C (p less than 0.05). These results suggest that low dose of dobutamine during reperfusion is effective to enhance hemodynamic parameters without deterioration of myocardial metabolism, and furthermore combined use of dobutamine and diltiazem is more effective to protect myocardial metabolism and ultrastructure from reperfusion damage in addition to improvement of hemodynamic parameters.

Animals↗