Biomedical subjects

Y Okamura

Publications and source records attributed to Y Okamura.

At least 55 records · Page 3Linked to original sources

PubMed2000

Two-dimensional analysis of proteins specific to the bacterial magnetic particle membrane from Magnetospirillum sp. AMB-1.

We report the identification of five proteins expressed specifically on the bacterial magnetic particle (BMP) membrane of Magnetospirillum sp. AMB-1. These proteins are major components of the BMP membrane. The molecular weights were determined to be 12.0, 16.0, 24.8, 35.6, and 66.2 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Of these five, the 16.0-kDa protein was the most abundant in the BMP membrane. Furthermore, the 16.0-kDa protein consisted of two components each of differing pI. The 35.6-kDa protein was the second most abundant protein of the five detected.

Bacterial Proteins↗

PubMed2000

Glutathione depletion enhances the formation of superoxide anion released into hepatic sinusoids after lipopolysaccharide challenge.

BACKGROUND: We examined the effects of glutathione depletion on the level of superoxide anion released into hepatic sinusoids after lipopolysaccharide challenge. METHODS: Rats were given 1 mg/kg of maleic acid diethyl ester to deplete glutathione in vivo and then 0.5 mg/kg body weight of lipopolysaccharide. RESULTS: This treatment significantly depleted serum reduced glutathione (32.7 +/- 1.7 vs. 23.0 +/- 3.2 mM, p = 0.002). However, it did not affect the serum oxidized glutathione concentration (2.88 +/- 0.56 vs. 3.10 +/- 0.78 mM, not significant). The lipopolysaccharide challenge caused significant superoxide anion formation as compared with controls (0.12 +/- 0.04 vs. 0.22 +/- 0.05 o.d., p < 0.001), and it was enhanced significantly by glutathione depletion (0.28 +/- 0.04 o.d., p < 0.05). There were no significant differences in levels of lipopolysaccharide (2142 +/- 452 vs. 2503 +/- 612 pg/ml) and tumor necrosis factor alpha (277 +/- 186 vs. 252 +/- 88 pg/ml) after the lipopolysaccharide challenge between the glutathione-depleted and nondepleted rats. Moreover, the purine nucleoside phosphorylase/glutamic-pyruvic transaminase ratio in liver perfusates, a marker of damage to endothelial cells in hepatic sinusoids, was significantly higher in the glutathione-depleted rats than in the nondepleted rats. CONCLUSIONS: The reduced form of glutathione can decrease levels of the superoxide anion released into hepatic sinusoids and can decrease subsequent damage to endothelial cells in these sinusoids caused by lipopolysaccharide; that is, it can reduce lipopolysaccharide-induced liver injury.

Animals↗

PubMed2000

[Management strategy for patients with coronary artery disease associated with valve disease].

BACKGROUND: The indication of combined operation of coronary artery bypass (CAB) and valve surgery is controversial. METHODS: Between April 1992 and January 2000, 13 patients underwent a combined operation with CAB and valve replacement, and 4 patients (2 were overlapped) who had had a previous CAB underwent a reoperative valve replacement. RESULTS: One patient who underwent AVR and reCAB 11 years after the initial CAB died. Another patient with preoperative MRSA pneumonia and received MVR and CAB died 4 months after surgery with MRSA sepsis. However, others showed an excellent post-operative course. The causes of necessitating the reoperation were: unawareness of aortic stenosis at the initial emergency CAB in 1 patient, progression of aortic stenosis in 1 patient, progression of aortic regurgitation in 1 patient, and progression of mitral regurgitation in 1 patient. CONCLUSION: The results of the combined CAB and valve replacement operation were acceptable. Patients with mild-moderate valve disease should be considered as candidates for valve surgery at the time of CAB.

Aged↗

PubMed2000

[A case report of a successful surgical treatment for infective endocarditis involving four valves in a elderly patient with ventricular septal defects].

A 72-year-old female was examined because of acute congestive heart failure. Echocardiogram revealed vegetations on aortic and pulmonary valve, regurgitation of four valves, and perimembraneous ventricular septal defect. Aortic valve replacement, mitral valve replacement, repair of tricuspid valve using a Carpentier ring, partial resection of pulmonary valve, and direct closure of VSD was performed. Pathological finding of resected valves showed acute endocarditis. A patient resumed social activities after surgery.

Aged↗

PubMed1999

Subfamily-specific posttranscriptional mechanism underlies K(+) channel expression in a developing neuronal blastomere.

Na(+) and K(+) channels are the two key proteins that shape the action potentials in neurons. However, little is known about how the expression of these two channels is coordinated. To address this issue, we cloned a Shab-related K(+) channel gene from ascidian Halocynthia roretzi (TuKv2). In this animal, a blastomere of neuronal lineage isolated from the 8-cell embryo expresses single Na(+) channel and K(+) channel genes after neural induction. Expression of a dominant negative form of TuKv2 eliminated the native delayed rectifier K(+) currents, indicating that the entire delayed rectifier K(+) current of the neuronal blastomere is exclusively encoded by TuKv2. TuKv2 transcripts are expressed more broadly than Na(+) channel transcripts, which are restricted to the neuronal lineages. There is also a temporal mismatch in the expression of TuKv2 transcript and the K(+) current; TuKv2 transcripts are present throughout development, whereas delayed rectifier K(+) currents only appear after the tailbud stage, suggesting that the functional expression of the TuKv2 transcript is suppressed during the early embryonic stages. To test if this suppression occurs by a mechanism specific to the TuKv2 channel protein, an ascidian Shaker-related gene, TuKv1, was misexpressed in neural blastomeres. A TuKv1-encoded current was expressed earlier than the TuKv2 current. Furthermore, the introduction of the TuKv2-expressing plasmid into noninduced cells did not lead to the current expression. These results raise the possibility that the expression of TuKv2 is post-transcriptionally controlled through a mechanism that is dependent on neural induction.

Amino Acid Sequence↗

PubMed1999

A Retrospective Study of Breast Cancer Patients Treated with Quadrantectomy without Radiation Therapy.

BACKGROUND: Radiation therapy after breast-conserving surgery (BCS) reduces the risk of local recurrence. However, whether radiation therapy is necessary forall patients undergoing BCS remains unclear. METHODS: In order to determine the selection criteria for patients who can safely omit radiation therapy and to confirm the survival benefit of quadrantectomy without radiation therapy, we reviewed 107 patients who underwent quadrantectomy without radiation therapy between February 1988 and July 1995. RESULTS: The 5-year overall survival, disease-free survival and cumulative local recurrence rates were 93.7%, 80.7% and 12.1% respectively. There were no significant differences of 5-year overall survival (94.0% vs 94.1%) and disease-free survival rates (83.1% vs 70.0%) between patients with or without tamoxifen. The 5-year cumulative local recurrence rate of patients with tamoxifen, however, tended to be lower (p = 0.0810) than that of patients without tamoxifen. The 5-year cumulative local recurrence rate of the patients aged 45 or less was significantly higher than that of patients aged from 45 to 55 years and those over 55 (p= 0.0090 and 0.0089, respectively). In ER positive patients, the 5-year cumulative local recurrence rate of patients with tamoxifen tended to be lower (p= 0.0791) than that of patients without tamoxifen. CONCLUSION: The survival rate of quadrantectomy without radiation therapy wasacceptable. While the risk of local recurrence following quadrantectomy withoutradiation therapy is substantial, radiation therapy following quadrantectomy might not be necessary in elderly ER positive women receiving adjuvant tamoxifen therapy.

Journal Article↗

PubMed1999

Cross-coupling between voltage-dependent Ca2+ channels and ryanodine receptors in developing ascidian muscle blastomeres.

1. Ascidian blastomeres of muscle lineage express voltage-dependent calcium channels (VDCCs) despite isolation and cleavage arrest. Taking advantage of these large developing cells, developmental changes in functional relations between VDCC currents and intracellular Ca2+ stores were studied. 2. Inactivation of ascidian VDCCs is Ca2+ dependent, as demonstrated by two pieces of evidence: (1) a bell-shaped relationship between prepulse voltage and amplitude during the test pulse in Ca2+, but not in Ba2+, and (2) the decay kinetics of Ca2+ currents (ICa) obtained as the size of tail currents. 3. During replacement in the external solution of Ca2+ with Ba2+, the inward current appeared biphasic: it showed rapid decay followed by recovery and slow decay. This current profile was most evident in the mixed bath solution (2 % Ca2+ and 98 % Ba2+, abbreviated to '2Ca/98Ba'). 4. The biphasic profile of I2Ca/98Ba was significantly attenuated in caffeine and in ryanodine, indicating that Ca2+ release is involved in shaping the current kinetics of VDCCs. After washing out the caffeine, the biphasic pattern was reproducibly restored by depolarizing the membrane in calcium-rich solution, which is expected to refill the internal Ca2+ stores. 5. The inhibitors of endoplasmic reticulum (ER) Ca2+-ATPase (SERCAs) cyclopiazonic acid (CPA) and thapsigargin facilitated elimination of the biphasic profile with repetitive depolarization. 6. At a stage earlier than 36 h after fertilization, the biphasic profile of I2Ca/98Ba was not observed. However, caffeine induced a remarkable decrease in the amplitude of I2Ca/98Ba and this suppression was blocked by microinjection of the Ca2+ chelator BAPTA, showing the presence of caffeine-sensitive Ca2+ stores at this stage. 7. Electron microscopic observation shows that sarcoplasmic membranes (SR) arrange closer to the sarcolemma with maturation, suggesting that the formation of the ultrastructural machinery underlies development of the cross-coupling between VDCCs and Ca2+ stores.

Animals↗

PubMed1999

Healing of the intimal dissection of the internal thoracic artery graft.

We report healing of the intimal dissection of an internal thoracic artery graft. Triple coronary artery bypass grafting was performed using left internal thoracic artery and saphenous vein grafts. One month after operation, the intimal dissection of the internal thoracic artery graft was clearly visible by coronary angiography; however, after 1 year of only medical treatment consisting of warfarin, ticlopidine, and nitrate, the intimal dissection was undetectable by coronary angiography.

Aged↗

PubMed1999

Iodine-impregnated drapes enable recording of precordial electrocardiogram.

Although we believed that the use of a polyester film drape for primary elective open sternum with delayed sternal closure made it impossible to record precordial electrocardiograms on the drape, we confirmed that it is possible to record electrocardiograms on an iodine-impregnated drape due to the iodine anion electrical conductibility.

Electric Conductivity↗

PubMed1999

Splenectomy attenuates superoxide anion release into the hepatic sinusoids after lipopolysaccharide challenge.

BACKGROUND/AIMS: The aim of this study was to determine whether the spleen contributes to superoxide anion release into the hepatic sinusoids and subsequent damage to endothelial cells of the hepatic sinusoids after lipopolysaccharide challenge. METHODS: Rats were given 2 mg/kg body weight lipopolysaccharide. Three hours after the treatment, superoxide anion release into the hepatic sinusoids was examined in a liver perfusion model using the cytochrome C method. Damage to endothelial cells of the hepatic sinusoids was assessed from the purine nucleoside phosphorylase/glutamic-pyruvic transaminase ratio in the liver perfusate. To further characterize the mechanisms behind these changes, these studies were done in rats given superoxide dismutase or an anti-TNFalpha antibody. To study whether the spleen plays a role in the mechanisms, experiments with splenectomized rats were performed. RESULTS: Lipopolysaccharide challenge resulted in superoxide anion release into the hepatic sinusoids and damage to endothelial cells of the hepatic sinusoids. These changes were significantly attenuated by the treatments with superoxide dismutase or an antibody against TNFalpha, as well as by splenectomy. The hepatic macrophage and Kupffer cell populations after lipopolysaccharide challenge were significantly smaller in the rats given splenectomy than in those given a sham operation. There were no significant differences in the neutrophil populations between the two groups. Levels of TNFalpha were significantly lower in the former than the latter, whereas there were no significant differences in levels of Interleukin-8 between the two groups. CONCLUSIONS: Splenectomy reduced the superoxide anion release into the hepatic sinusoids caused by the lipopolysaccharide challenge and subsequent damage to endothelial cells of the hepatic sinusoids. This supports the view that splenectomy has a protective effect in lipopolysaccharide-induced liver injury.

Animals↗

PubMed1999

A new instrument for hemostatic vascular management in endoscopic surgery: diode laser (STATLase-SDL) and its handpiece (dual hook).

OBJECTIVE: The authors described experimental data in hemostatic vascular transection using a STATLase-SDL with a 780-865 nm GaA/As diode wavelength and its handpiece, Dual Hook (DH). SUMMARY BACKGROUND DATA: The STATLase-SDL and DH are newly developed devices for endoscopic surgery. It seems that the device has improved hemostatic cutting ability. METHODS: The DH was applied to the abdominal aorta (< 2 mm) of Japanese white rabbits (n = 15) under general anesthesia. Tissue temperature during laser transection and interluminal bursting pressures were measured. Histopathological examinations at the cut end were carried out by hematoxylin-eosin (H&E) and elastica Van Gleson's (EVG) stainings. To investigate short-term effects 11 days postoperatively, the cut ends of the vessels were examined histologically in the heminephrectomy group. RESULTS: The DH hemostatistically cut through arteries up to 2 mm in diameter. Temperatures at the inner hook and in adjunct tissue were higher than 160 degrees C, while that at the outer hook was lower than 80 degrees C. The bursting pressures immediately after transection was 307.2 +/- 35.2 mm Hg at a laser power of 8 W (n = 5), and 295.6 +/- 28.7 mm Hg at 10 W (n = 5). Histological examination of the transected sites on the vessels revealed well-opposed tissue welding of the vascular wall. Absence of fragmentation in the welding of the internal elastic lamina is crucial for closure of the vessel stump. Up to 11 days postoperatively, there were no direct complications related to the use of the DH. CONCLUSIONS: The STATLase-SDL and DH have good hemostatic cutting ability and might be suitable for endoscopic surgery.

Angioscopes↗

PubMed1999

Superoxide anion release into the hepatic sinusoid after an acute ethanol challenge and its attenuation by Kupffer cell depletion.

Superoxide anion release into the hepatic sinusoids and subsequent damage to the endothelial cells of the hepatic sinusoids after ethanol challenge was examined. A 250 mg/kg body weight/hr dose of ethanol was given to rats for 3 hr, and superoxide anion release into the hepatic sinusoids was examined in a liver perfusion model using the cytochrome c method. Ethanol treatment resulted in superoxide anion release into the hepatic sinusoids (0.20 +/- 0.01 vs. 0.12 +/- 0.02 o.d., p < 0.05) and an increase in the purine nucleoside phosphorylase/alanine aminotransferase ratio in the liver perfusate, a marker of damage to the endothelial cells of the hepatic sinusoids (0.003 +/- 0.002 vs. 0.008 +/- 0.002; p < 0.05). Tumor necrosis factor-alpha was not detectable in either group, and there were no significant differences in the population of hepatic macrophages, leukocytes, or Kupffer cells between the two groups. To clarify the role of Kupffer cells in the mechanism, 10 mg/kg of body weight of gadolinium chloride was given to rats twice, 24 hr apart, resulting in depletion of ED2-positive cells from the hepatic lobules. The superoxide anion release after the ethanol challenge was significantly attenuated in the Kupffer cell-depleted rats, compared with the controls (0.14 +/- 0.02; p < 0.05, compared with ethanol alone). The change was associated with a significant decrease in the purine nucleoside phosphorylase/alanine aminotransferase ratio in the liver perfusate (0.004 +/- 0.002; p < 0.05, compared with ethanol alone). Ethanol causes superoxide anion release into the hepatic sinusoid and subsequent damage to the sinusoidal endothelial cells. These changes were reduced by Kupffer cell depletion. This supports the view that Kupffer cell depletion has a protective effect on ethanol-induced liver injury.

Alanine Transaminase↗

PubMed1999

Evidence for ethanol oxidation by Kupffer cells.

Ethanol oxidation in Kupffer cells was investigated by measuring 14C-acetate formation from 14C-ethanol, and the role of aldehyde dehydrogenase 2 (ALDH2) in this process was also examined. Formation of 14C-acetate from 20 mM of 14C-ethanol was significantly increased in medium-containing Kupffer cells (9,003 +/- 2,066 cpm/5 x 10(6) cells), compared with medium containing no cells (1,826 +/- 46 cpm, p < 0.01), or containing acid-killed Kupffer cells (1,629 +/- 210 cpm, p < 0.01). Ethanol formation was significantly attenuated when 20 and 200 microM cyanamide or 2 microM disulfiram were given. Reverse transcriptase-polymerase chain reaction demonstrated that Kupffer cells carry mRNA for ALDH2. These findings indicate that Kupffer cells can oxidize ethanol to acetate. ALDH2 may participate in this process, especially in the conversion of acetaldehyde to acetate.

Acetaldehyde↗

PubMed1999

[Coronary artery bypass grafting technique to minimize the usage of metallic materials].

Some metallic materials are widely used for coronary artery bypass surgery. There is no problem using the metallic materials themselves. However, metallic artifact interferes with the interpretation and reduces the sensitivity of the MRI. To minimize the utilization of metallic materials, we applied absorbable nonmetallic clips and used an ultrasonically activated scalpel to harvest the arterial grafts. We also applied polyester suture instead of the stainless steel sternal wire. We believe this technique will allow increased MRI usage for patients who undergo coronary artery bypass surgery.

Coronary Artery Bypass↗

PubMed1999

[Indication and outcome in emergent coronary artery bypass graft for acute coronary syndrome].

Among 462 cases receiving coronary artery bypass graft (CABG) during the period from November 1991 to January 1999, emergency operation was performed within 24 hours for 27 cases. Male-to-female ratio was 21:6, and age of patients ranged from 50 to 83 years (average age: 65.9 years). Intra aortic balloon pumping (IABP) was used from preoperative period for 25 cases, and PCPS was used for one case. Operation was performed under cardiac arrest in 25 cases and under ventricular fibrillation in 2. Average number of grafts was 2.4 +/- 1.0 and perioperative mortality was 25.9%. The results of emergency cases were extremely low compared with mortality of palliative operation of 3.4%, whereas mortality has been improved to 12.5% (2/16) in the last two years. These results suggest that it is important for the improvement of the outcome in emergency CABG to prevent aggravation of circulatory dynamics and to shift to operation under stable conditions.

Aged↗

PubMed1998

Basic fibroblast growth factor induction of neuronal ion channel expression in ascidian ectodermal blastomeres.

1. Cleavage-arrested anterior animal (a4-2) blastomeres isolated from eight-cell embryos of Halocynthia aurantium differentiated into neuronal type cells expressing neuron-specific ion channels when they were treated with basic fibroblast growth factor (bFGF). This induction process was very similar to that when a4-2 blastomeres were cultured in contact with anterior vegetal (A4-1) blastomeres from the same embryos or when treated with subtilisin, a serine protease. 2. Other growth factors, transforming growth factor (TGF) beta1, activin A, epidermal growth factor (EGF) and nerve growth factor (NGF), had no effect on the default epidermal differentiation of cleavage-arrested a4-2 blastomeres. 3. Messenger RNA of the ascidian neuronal Na+ channel, TuNa I, was detected using RT-PCR in a4-2-derived partial embryos of Halocynthia aurantium as well as in the cleavage-arrested a4-2 blastomeres treated with bFGF, confirming the neural inducer activity of bFGF during ascidian embryogenesis. 4. bFGF was effective at concentrations as low as 1 ng ml-1 in inducing neuronal ion channels in cleavage-arrested a4-2 blastomeres. EC50 for neuronal differentiation was estimated to be around 8 ng ml-1, and the maximum effect of 90 % neuronalization was obtained with above 100 ng ml-1. 5. For induction of neuronal differentiation, bFGF was required to be continuously present 8 to 14 h after fertilization. A similar time window was required for cell-contact induction, but it was considerably shorter for subtilisin induction. 6. We discuss whether activation of receptor tyrosine kinase is a common pathway for neural induction by bFGF, subtilisin, and cell-contact with A4-1 blastomeres.

Animals↗

PubMed1998

[A case report of recurrent self inserted needle in heart].

A 17-year-old female who had, on two occasions, inserted a total of 7 needles into her heart and chest wall, resulting in autolesion on both occasions, was examined. On the first occasion, because the needle end was recognizably protruding from the right ventricle, we successfully removed the needle without using ECC. No complications arose prior to discharge, after which she regularly visited the psychiatric department for treatment. Two months after discharge, she again inserted needles into her chest wall and was admitted to hospital. At that time, five needles were evident in the chest wall. During preparation for removal of the needles under local anesthetic, she escaped from the room. When found in a ward several hours later, six needles were embedded in her chest wall, the sixth, most recently inserted needle was an injection needle. Due to the depth to which the needle had been inserted in the heart, neither the point nor end were visible, and thus the needle had to be removed using ECC and fluoroscopy.

Adolescent↗

PubMed1998

Interleukin-6 and "complex" cardiac myxoma.

A rare case of "complex" cardiac myxoma is reported. Complex cardiac myxoma manifests with more constitutional signs than the sporadic type. These constitutional signs are known to be associated with the overproduction of interleukin-6 by cardiac myxomas. In our study, immunohistochemical staining of the myxoma for interleukin-6 was strongly positive. The serum interleukin-6 level decreased after surgical removal of the tumor and has remained undetectable for the past 2 years.

Adolescent↗