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Biomedical subjects

S Yamamura

Publications and source records attributed to S Yamamura.

At least 109 records · Page 6Linked to original sources
PubMed1994

Isolation and structure elucidation of the major photodegradation products of pirmenol hydrochloride.

Column chromatography, thin-layer chromatography, high-performance liquid chromatography, nuclear magnetic resonance spectrometry, and high-resolution mass spectrometry were employed to separate and identify the photodegradation products of pirmenol hydrochloride [(+/-)-cis-alpha-[3-(2,6-dimethyl-1-piperidinyl)propyl]-alpha-phenyl-2- pyridinemethanol monohydrochloride monohydrate], a new antiarrhythmic drug. A methanol solution of pirmenol was irradiated using a low-pressure mercury lamp. The solution afforded four major degradation products, three of which were identified as 3-(cis-2,6-dimethylpiperidinyl)propyl 2-(2-pyridyl)phenyl ketone, 2-(2-pyridyl)benzoic acid, and methyl 2-(2-pyridyl)-benzoate. The degradation followed apparent-first-order reaction kinetics. In addition, the possible photodegradation pathways are discussed with reference to reaction mechanisms.

Anti-Arrhythmia Agents↗
PubMed1994

Blood flow and kinetics of smooth muscle cell proliferation in canine autogenous vein grafts: in vivo BrdU incorporation.

The effects of blood flow on the kinetics of smooth muscle cell (SMC) proliferation were examined in canine autogenous vein grafts with a distal poor run-off model. The in vivo bromodeoxyuridine (BrdU, a thymidine analogue) incorporation method was used to label proliferating SMCs in each layer of the vein graft. The BrdU labeling index (LI) was defined as a percentage of labeled cells compared to the total number of SMCs, and BrdU LIs were measured in the media and the intima of the graft. The development of intimal thickening of grafts was accelerated at 2 to 4 weeks after implantation. In poor run-off limbs with an abnormal blood flow condition, as characterized by a low flow and a low shear stress variation, the intima of the graft thickened more progressively than that in control limbs with a normal blood flow. In both groups, the medial BrdU LIs reached a maximum 3 to 5 days after implantation and decreased thereafter. The peak of the intimal BrdU LIs occurred at 1 week in both groups. The intimal LIs of the grafts in poor run-off limbs (6.34% at 1 week and 2.97% at 2 weeks) were significantly higher than those in control limbs (5.34 and 1.98%) for 2 weeks after implantation (P < 0.05). The medial SMC proliferation and the following intimal SMC proliferation of vein grafts were accelerated prior to development of the intimal thickening. SMC proliferation in the intima was prominent in a poor run-off limb with a low flow and a low shear stress variation.

Animals↗
PubMed1994

Magnetic resonance imaging of inflammatory reaction in osteoid osteoma.

Between 1988 and 1993, 16 cases of osteoid osteoma were examined by magnetic resonance imaging (MRI). MRI clearly visualized the extent of inflammation in the bone marrow and soft parts that is difficult to observe with other diagnostic techniques. The degree of inflammation varied among the patients. This might be associated with the anatomical relationship between the nidus and the cortex. The high sensitivity of MRI, unfortunately, may lead to an erroneous interpretation in lesions accompanied by inflammatory responses of the bone marrow or soft parts, such as osteoid osteoma. However, these reactions on MRI may offer a key to the pathogenesis of osteoid osteoma, a unique bone neoplasm.

Adolescent↗
PubMed1994

[The importance of dose intensity in preoperative chemotherapy for osteosarcoma--retrospective analysis of a short intensive chemotherapy regimen preoperatively using high-dose methotrexate and cisplatinum].

A retrospective investigation was performed on the significance of dose intensity in preoperative chemotherapy for osteosarcoma. In this paper, we studied 29 patients, who had classical stage II-B osteosarcoma and received preoperative treatment consisting of high dose methotrexate (HD-MTX) and/or cisplatinum (CDDP) between 1985 and 1991. Preoperative dose intensity was calculated in the following two ways. 1. Total dose of MTX and CDDP administered during initial five weeks: MTX (g)/10/m2 + CDDP(mg)/100/m2 2. Dose intensity of MTX and CDDP from initiation of treatment (I) to resumption of postoperative chemotherapy (R): MTX (g)/10/m2 + CDDP (mg)/100/m2 / days from (I) to (R)/ideal period of new regimen (63 days) Continuous disease free survival rate (CDFR) was significantly higher in the group receiving preoperative chemotherapy at higher dose intensity (> 3.0). Supplementary administration of adriamycin (ADR) to CDDP/MTX was not favorable in the preoperative stage, because it put off the following therapy and diminished the dose intensity. Since July 1989, we have tried a short intensive preoperative chemotherapy regimen: weekly two cycles of CDDP 100 mg/m2 intravenously, followed by weekly two cycles of HD-MTX 10g/m2. Surgery was scheduled six weeks after beginning treatment, and postoperative chemotherapy was started three weeks after surgery. Twenty patients have been treated by this regimen to date. All patients remain disease free, and six are CDF beyond 24 months.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

The reversibility of impaired prostacyclin production of the vein graft.

The effects of changes in shear stress (shear stress variation) on production of prostacyclin (PGI2) were examined in canine autologous vein grafts, which were implanted in the poor or normal distal runoff limbs. Four weeks after grafting, the vein grafts were perfused ex vivo and PGI2 was assayed as 6-ketoprostaglandin F1 alpha. The vein grafts were perfused under constant flow for the first 30 min and then under pulsatile flow simulating an abnormal flow with a low shear stress variation or a normal flow with a high shear stress variation for the next 30 min. Basal production rates (30-min cumulative PGI2 production) of vein grafts implanted in the poor runoff and normal runoff limbs were 1.97 +/- 0.71 and 2.19 +/- 0.40 ng/cm2, respectively, with no significant difference. Pulsatile flow effects (increased PGI2 production between 30 and 60 min) of simulated abnormal versus normal flow were 0.50 +/- 0.50 ng/cm2 versus 2.31 +/- 1.87 ng/cm2 in vein grafts implanted in poor runoff limbs (P < 0.05) and 0.48 +/- 0.41 ng/cm2 versus 3.48 +/- 1.08 ng/cm2 in vein grafts implanted in normal runoff limbs (P < 0.01), respectively. There were no significant differences in simulated normal flow effects between poor runoff limbs and normal runoff limbs. The results indicate that the release of PGI2 in vein grafts may decrease in the presence of an abnormal blood flow with a low shear stress variation. In addition, it is suggested that even vein grafts implanted in the poor runoff could increase PGI2 production once the grafts were placed into normal arterial circulation.

Animals↗
PubMed1993

[Preparation and structural elucidation of insularine-N-oxides].

Oxidation of insularine (I) with m-chloroperbenzoic acid yielded four insularine-N-oxides. Two of them are identical in every respect with our insularine-2 beta-N-oxide (II) and insularine-2' beta-N-oxide (III), two rare examples of naturally occurring head-to-tail bisbenzylisoquinoline N-oxides newly isolated from Cyclea sutchuenensis, which confirmed the structures of the two novel natural N-oxides. The other two are new compounds and their structures have been established as insularine-2' alpha-N-oxide (IV) and insularine-2 beta,2' beta-N, N-dioxide (V), on the basis of spectral data (UV, IR, 1HNMR, NOEDS AND MS) analysis.

Cyclic N-Oxides↗
PubMed1993

[Two novel bisbenzylisoquinoline alkaloids from Cyclea sutchuenensis Gagnep].

In addition to the known cycleanine (I) and d-isochondodendrine (II), two novel bisbenzylisoquinoline alkaloids named isocycleanine (III) and sutchuenensine (IV) have been isolated from the roots of Cyclea sutchuenensis Gagnep grown wild in Sichuan province, China. III was established as the epimer of I and IV, as a new type of head-to-tail bisbenzylisoquinoline alkaloid with two diarylether bridges in between C-8 to C-12' and C-12 to C-7' on the basis of physical constants and spectral data (UV, IR, EIMS, 1HNMR and NOEDS).

Alkaloids↗
PubMed1993

Impaired endothelial prostacyclin production of the canine vein graft in a poor distal runoff limb.

BACKGROUND: Because blood flow modulates endothelial prostacyclin production, the extent of this production in autologous vein grafts implanted in poor distal runoff limbs needed to be examined. METHODS: Endothelial prostacyclin production in canine autologous vein grafts was measured in poor distal runoff limbs (poor runoff group) and compared with findings in normal runoff limbs (control group). Vein grafts were perfused in a closed circuit at 3 days and 1, 2, 3, and 4 weeks after implantation; after perfusion for the first 30 minutes in a steady flow (basal prostacyclin production), the grafts were exposed to arachidonic acid (stimulated prostacyclin production) for the following 30 minutes. Prostacyclin, as the metabolite 6-keto-PGF1 alpha, was radioimmunoassayed. RESULTS: Basal and stimulated prostacyclin production increased in both groups during a period of time after implantation. At 2 weeks when endothelialization was complete, prostacyclin production in the poor runoff group was impaired, compared with the findings in the control group, and this difference increased with time. At 4 weeks the stimulated prostacyclin production was 18.91 +/- 4.03 ng/cm2 in the control group and 11.60 +/- 1.67 ng/cm2 in the poor runoff group (p < 0.05). CONCLUSIONS: We propose that the impaired capacity of the vein graft to produce prostacyclin in a poor distal runoff may lead to loss of graft patency in reconstructed arteries.

Animals↗
PubMed1992

Fluorescent fibre-optic immunosensing system based on complement lysis of liposome containing carboxyfluorescein.

A novel type of fibre-optic immunosensing system has been developed. Agar gel-immobilized liposomes containing carboxyfluorescein were attached to the tip of an optical fibre. Complement-mediated immunolysis of the liposome was fluorometrically detected through the fibre. By using dinitrophenyl (DNP) hapten-loaded liposomes, concentrations as low as 500-fold diluted anti-DNP antibody and 0.76 CH50 ml-1 of complement were detected.

Biosensing Techniques↗
PubMed1992

High aortic occlusion associated with lupus anti-coagulant.

Lupus anti-coagulant (LAC) has been recognised in association with venous and arterial thrombotic events. We retrospectively investigated the relationship between LAC and 21 patients with juxtarenal high aortic occlusion. Four of the 21 patients were LAC positive (19%), one of whom was a woman suffering from systemic lupus erythematosus (SLE). The three men had neither SLE nor any other connective tissue disease. The mean age of the four patients was 43.5 years and three of them (75%) were younger than 50 years of age. By contrast, the mean age of the 17 patients without LAC was 59.9 years and 14 of them (82.4%) were older than 50 years. The postoperative courses in all four patients with LAC undergoing arterial reconstructions were uneventful. Two patients were treated by either anti-coagulation or anti-platelet agents, postoperatively. The present paper demonstrates for the first time that, in patients with juxtarenal high aortic occlusion, the incidence of LAC positivity is higher in younger patients (below 50) than in older patients (above 50). In addition, our results show that a preoperative evaluation of the presence of LAC is required in cases with juxtarenal high aortic occlusion, particularly when the partial thromboplastin time (PTT) is prolonged and the patients are younger than 50 years old.

Adult↗
PubMed1992

Isolation and identification of lepidimoide, a new allelopathic substance from mucilage of germinated cress seeds.

A new allelopathic substance that promoted the shoot growth of different plant species but inhibited the root growth was isolated as an amorphous powder from mucilage of germinated cress (Lepidium sativum L.) seeds. This substance was identified as sodium 2-O-rhamnopyranosyl-4-deoxy-threo-hex-4-enopyranosiduronate (designated lepidimoide) from the mass and the nuclear magnetic resonance and infrared spectra coupled with some chemical evidence. Lepidimoide promoted the hypocotyl growth of etiolated Amaranthus caudatus L. at concentrations higher than 3 mum and inhibited the root growth at concentrations higher than 100 mum. The growth-promoting activity in hypocotyls was 20 or 30 times as much as that of gibberellic acid.

Journal Article↗
PubMed1992

[A case report of AML M0:CD7, 33 (+) AML M0 case initially presented with cervical lymphadenopathy].

A 59-year-old man was admitted because of generalized lymphadenopathy with fever and vomiting. His peripheral blood showed leukocytosis with a WBC of 93,500/microliters, and the bone marrow picture revealed a predominance of blast cells. The blasts were negative for peroxidase, alpha-naphthyl butyrate esterase and PAS, and had the phenotype of CD 7, 13 and 33 positive. A diagnosis of AML M0 was made, based on the criteria of the NCI-sponsored workshop in 1988. His initial status had been compromised by acute renal failure which necessitated hemodialysis. He responded partially to chemotherapy consisting of daunorubicin, cytarabine and prednisolone. However leukemia recurred and the patient suffered from various episodes of infection and died six months after admission. The Southern blotting showed the germ line configuration for TCR-beta chain and immunoglobulin heavy chain genes. No messenger RNA was detected for myeloperoxidase, c-myc and c-jun, while c-fms, c-fos and c-myb were expressed on Northern blotting. It is intriguing to detect c-fms and c-fos expression in these poorly differentiated leukemic cells.

Antigens, CD↗
PubMed1991

Intraoperative flow waveform analysis aids in preventing early graft failure following reconstruction of arteries of the legs.

To enable early detection and treatment of vascular defects leading to early graft failure, intraoperative flow waveform analyses were carried out during lower extremity arterial reconstructions in 226 patients undergoing 102 aortoiliac/femoral and 124 femorodistal bypass grafts. Flow waveform types III or IV indicated early graft failure. These were noted in seven grafts (6.9%) in the aortoiliac/femoral position and in eight grafts (6.5%) in the femorodistal position. The main cause of the abnormal flow waveform pattern was misinterpretation of preoperative arteriographic findings in aortoiliac/femoral reconstructions and technical errors in anastomoses in femorodistal reconstructions. Of 15 grafts with an abnormal flow waveform pattern, 13 were effectively repaired with patch angioplasty, graft extension, or replacement with thrombectomy. In two grafts, the repair failed and amputation had to be done. Thus, intraoperative flow waveform analysis is a simple, useful, and safe method to detect vascular defects leading to early graft failure. Unless assessment of preoperative arteriographic findings in aortoiliac/femoral reconstructions are accurate and anastomotic techniques in femorodistal reconstructions are refined, early graft failure may occur.

Aged↗
PubMed1991

Laser thermal angioplasty for early repair of anastomotic stenosis after lower extremity arterial reconstruction: initial experience.

Laser thermal angioplasty with a sapphire hot-tip Nd-YAG laser system was effectively used for five grafts with anastomotic stenotic lesions which occurred after femoro-popliteal arterial reconstructions. Stenotic lesions were detected by a combination of Doppler flow waveform analysis and ankle/brachial index measurement in 32 femoro-popliteal and five femoro-tibial arterial bypass grafts in the postoperative period. The laser probe used was 3 to 4 mm in diameter. There were no perforations of the arterial wall caused by thermal ablation, even with repeated pulses of 40 watts of laser energy for 3 s. Contact Nd-YAG laser thermal angioplasty using this rounded, 3-4 mm hot-tip facilitated effective widening of the lumen of the anastomotic stenotic lesion. All patients remain well at follow-up from 9 to 20 months after laser thermal angioplasty.

Aged↗
PubMed1991

Simulated blood flow and the effects on prostacyclin production in the dog femoral artery.

Effects of blood flow on the production of prostacyclin (PGI2) were examined in the canine femoral artery perfused ex vivo. Each artery was perfused in situ with medium 199, under conditions of simulated blood flow. To simulate the normal and abnormal blood flow waveforms at the same mean flow rate, we developed a flow apparatus capable of making various waveforms by changing the duration when the electromagnetic valve in the circuit was open. Group I (n = 7) was exposed to a steep acceleration waveform followed by a steep deceleration, as the normal flow waveform; group II (n = 7) was exposed to a gentle sloping waveform in the deceleration phase, as the abnormal flow waveform. PGI2 was measured as 6-ketoprostaglandin F1 alpha. PGI2 production was estimated as the cumulative production for the first 5 minutes (acute response) and as the production rate after the first 30 minutes (stable production rate). Under conditions of normal flow, the acute response was 5.87 +/- 2.16 ng/cm2/5 min, whereas under conditions of abnormal flow, the rate was 2.20 +/- 0.27 ng/cm2/5 min (p less than 0.01). Stable production rates were 82.5 and 37.5 pg/cm2/min, respectively (p less than 0.05). Both the acute response and the stable production rate of PGI2 production were greater under conditions of simulated normal flow as compared with findings in the case of an abnormal flow. Our working hypothesis is that the decreased production of PGI2, as well as a deterioration in the implanted graft, under conditions of abnormal blood flow leads to a loss of late patency of the reconstructed arteries.

6-Ketoprostaglandin F1 alpha↗
PubMed1991

[Altered expression of protooncogenes during clinical course in an AML case transformed from MDS].

The changes of expression of oncogenes in the mononuclear cells of MDS case was studied during his clinical course, in series. His bone marrow was considered to maintain its function partly in initial stage, since both peripheral blood and bone marrow responded to clinical episodes. However, his hematopoietic function was gradually impaired with the disease evolution to AML. We examined the expression of four oncogenes in the mononuclear cells of his three clinical stages, early RAEB-t, RAEB-t and AML, to study the cause of transformation from MDS to AML. Early RAEB-t cells expressed all oncogenes studied other than c-myb, while only c-myc was weakly observed in RAEB-t. AML cells expressed c-myc, c-jun and c-myb, except for c-fms. The expression of c-fms and c-jun of early RAEB-t was considered to reflect the monocytosis induced by infections, and the expressions of c-myb and c-myc of AML cells were regarded as one of malignant signs of tumor transformation. These findings suggest that the evolutional transformation of MDS to AML was affected by the altered expression of oncogenes.

Anemia, Refractory, with Excess of Blasts↗