Biomedical subjects

Yasuyuki Sasaki

Publications and source records attributed to Yasuyuki Sasaki.

13 recordsLinked to original sources

PubMed2006

Effective cellulose production by a coculture of Gluconacetobacter xylinus and Lactobacillus mali.

A microbial colony that contained a marked amount of cellulose was isolated from vineyard soil. The colony was formed by the associated growth of two bacterial strains: a cellulose-producing acetic acid bacterium (st-60-12) and a lactic acid bacterium (st-20). The 16S rDNA-based taxonomy indicated that st-60-12 belonged to Gluconacetobacter xylinus and st-20 was closely related to Lactobacillus mali. Cocultivation of the two organisms in corn steep liquor/sucrose liquid medium resulted in a threefold higher cellulose yield when compared to the st-60-12 monoculture. A similar enhancement was observed in a coculture with various L. mali strains but not with other Lactobacillus spp. The enhancement of cellulose production was most remarkable when sucrose was supplied as the substrate. L. mali mutants for exocellular polysaccharide (EPS) production were defective in promoting cellulose production, but the addition of EPS to the monoculture of st-60-12 did not affect cellulose productivity. Scanning electron microscopic observation of the coculture revealed frequent association between the st-60-12 and L. mali cells. These results indicate that cell-cell interaction assisted by the EPS-producing L. mali promotes cellulose production in st-60-12.

Cellulose↗

PubMed2006

Mycotic aneurysm of the distal aortic arch caused by Aspergillus.

We describe an unusual case of a thoracic aortic aneurysm caused by Aspergillus. A 70-year-old man underwent prednisolone and Ara-C treatments for a myelodysplastic syndrome. Blood examination revealed pancytopenia. Under these treatments, an aneurysm presented at the distal aortic arch. He underwent resection of the aneurysm with a graft repair covered by a pedicled omentum flap, followed by prolonged administration of micafungin and itraconazole for a mycotic aneurysm. The postoperative course was favorable without complications. Serum C-reactive protein became negative and he was discharged 2 months after the surgery. However, 4 months after the surgery, he died from worsening of the myelodysplastic syndrome. The prognosis for patients with mycotic aneurysms is poor due to their immunocompetent condition arising from underlying diseases. Therefore, in addition to prompt treatment with antifungal agents combined with surgical debridement, control of the underlying disease is essential for improving the outcome.

Aged↗

PubMed2006

Homemade endovascular treatment of postoperative aortobronchial fistulas.

Successful treatments of aortobronchial fistulas were achieved in two cases using a homemade endovascular stent graft. In one, a 75-year-old man was operated on for a distal arch aneurysm 11 years previously. In the other, a 73-year-old woman was operated on for a ruptured type B aortic dissection 2 months previously. In both cases, the chief complaint was repeated hemoptysis, and the communication between the aorta and the airway tract was at the distal anastomotic site in the descending aorta. To minimize risks associated with reoperation, endovascular stent grafting was selected electively. Postoperative courses were uneventful and there were no recurrences of hemoptysis.

Aged↗

PubMed2005

Purification, crystallization and preliminary X-ray analysis of a hexameric beta-glucosidase from wheat.

The wheat beta-glucosidase TaGlu1b, which is only active in a hexameric form, was tagged with 6xHis at the N-terminus, overexpressed in Escherichia coli and purified in two steps. The protein complexed with a substrate aglycone was crystallized at 293 K from a solution containing 10 mM HEPES pH 7.2, 1 M LiSO4 and 150 mM NaCl using the hanging-drop vapour-diffusion method. Diffraction data were collected to 1.7 A at the Photon Factory. The crystal belongs to space group P4(1)32, with unit-cell parameters a = b = c = 194.65 A, alpha = beta = gamma = 90 degrees. The asymmetric unit was confirmed by molecular-replacement solution to contain one monomer, giving a solvent content of 72.1%.

Crystallization↗

PubMed2005

Successful surgical treatment of a mycotic right coronary artery aneurysm complicated by a fistula to the right atrium.

We reported successful surgical treatment of a mycotic right coronary artery aneurysm complicated by a fistula to the right atrium in a 60-year-old man admitted to hospital because of acute worsening of renal function and erythroderma. After admission, he suffered from methicillin-resistant Staphylococcus aureus septicemia. Despite administration of vancomycin hydrochloride, a low-grade fever persisted. Subacute cardiac tamponade occurred three months after admission, and acute inferior wall myocardial infarction occurred two weeks after pericardial drainage. An emergent coronary angiography demonstrated a large saccular aneurysm of the right coronary artery forming a fistula to the right atrium and obstruction of the distal right coronary artery. We emergently resected the aneurysm including the right atrial wall and repaired the defect in the right atrium. Pathological examination of the aneurysmal wall revealed its mycotic nature; the postoperative course was uneventful.

Aneurysm, Infected↗

PubMed2005

Immunolocalization of platelet glycoprotein IIb/IIIa and P-selectin, and neutrophil-platelet interaction in human coronary unstable plaques.

Platelet aggregation at the site of plaque rupture or erosion is a dominant feature in the pathophysiology of plaque destabilization. To elucidate the role of glycoprotein (GP) IIb/IIIa in coronary plaque destabilization, we immunohistochemically studied the presence of GP IIb/IIIa in coronary atherectomy specimens obtained from patients with stable angina (SAP) and unstable angina pectoris (UAP). Moreover, we immunohistochemically investigated the presence of P-selectin, which is known to be a marker of platelet activation, in these specimens. All these patients underwent atherectomy at primary atherosclerotic lesions responsible for SAP (n=25) and UAP (n=23). Frozen samples were studied with antibodies against smooth muscle cells, macrophages, neutrophils, endothelial cells, GP IIb/IIIa and P-selectin. Immunoreactive positive areas for GP IIb/IIIa, P-selectin, and macrophages, respectively, were calculated using computer-aided planimetry, and numbers of neutrophils were also counted. In the culprit lesions of UAP patients, 17 of the 23 lesions (74%) contained GP IIb/IIIa positive platelet thrombi, and all these platelet thrombi were positive for P-selectin. In contrast, in the lesions of SAP patients, 3 of the 25 lesions (12%) showed staining positivity for GP IIb/IIIa and P-selectin. Quantitatively, the percentage of GP IIb/IIIa- and P-selectin-positive area was significantly higher (GP IIb/IIIa, P<0.0005; P-selectin, P<0.0001) in patients with UAP than in patients with SAP. The number of neutrophils was significantly higher (P<0.0005) in patients with UAP than in patients with SAP. Moreover, the percentage of GP IIb/IIIa-positive area showed a significant positive correlation with the number of neutrophils (r=0.66, p<0.0001). These findings strongly suggest that platelet activation and aggregation, leading to formation of platelet thrombi, and the interaction between activated platelets and neutrophils play a pivotal role in the pathogenesis of plaque destabilization in human coronary atherosclerotic lesions.

Blood Platelets↗

PubMed2005

Paradoxical cerebral embolism in a patient with Paget-Schroetter syndrome.

A 28-year-old man presented with transient speech disturbance and right hemiplegia. Computed tomography of the brain revealed a low-density area in the right cerebellum. A ventilation/perfusion lung scintiscan detected multiple perfusion defects in the both lungs and catheterization revealed pulmonary hypertension. Venography of the upper extremities revealed obstruction of the left subclavian vein. Furthermore, Doppler echocardiography revealed a right-to-left shunt via a patent foramen ovale. Those examinations demonstrated paradoxical cerebral embolism caused by Paget-Schroetter syndrome, which is a rare complication of the disorder. We hypothesize that the source of thrombi was the left subclavian vein and surgery was needed to prevent further thromboembolic events. At surgery, the upper half of the sternum was incised in the midline, and the left brachiocephalic vein was ligated. No thromboembolic episodes have occurred postoperatively.

Adult↗

PubMed2004

Influence of coronary artery disease on operative mortality and long-term survival after abdominal aortic aneurysm repair.

PURPOSE: This retrospective study was conducted to evaluate the effects of coronary artery disease (CAD) on short- and long-term survival after abdominal aortic aneurysm (AAA) repair. METHODS: One hundred consecutive patients underwent elective AAA repair between 1991 and 2002. Coronary angiography was performed in all patients, revealing significant coronary artery lesions in 47 (47%). Percutaneous transluminal coronary angioplasty (PTCA) was performed in 11 patients, 20 (median) days before the abdominal surgery. Abdominal aortic aneurysm repair was performed 60 (median) days after coronary artery bypass grafting (CABG) in five patients, and both procedures were performed simultaneously in two patients. RESULTS: The in-hospital mortality rate for AAA repair was 1.0%, but there was no cardiac-related operative morbidity or mortality. The 96 patients discharged were followed up for a mean period of 2.9 years (range 3-143 months). The cumulative survival rates after 1, 2, 3, and 5 years were 98%, 95%, 88%, and 77%, respectively. Only one patient (1%) died of myocardial infarction. There was no significant difference in the long-term survival of the CAD and non-CAD patients. CONCLUSIONS: These results emphasize the importance of routine coronary angiography and subsequent coronary revascularization to improve early and late survival rates after AAA repair.

Aged↗

PubMed2004

Saturated fatty acids suppress adrenocorticotropic hormone (ACTH) release from rat anterior pituitary cells in vitro.

We studied whether fatty acids modify adrenocorticotropic hormone (ACTH) release induced by stimulation with corticotropin-releasing hormone (CRH) from rat anterior pituitary cells. Stimulation with CRH (0.01-100 nmol/l) significantly and concentration-dependently increased ACTH release, which was synergistically enhanced by the simultaneous stimulation with 1 nmol/l arginine-vasopressin. Addition of saturated fatty acids (butyrate, caprylate, laurate, palmitate and stearate) in a medium at 1 mmol/l, despite effects on the basal release, significantly reduced the ACTH release induced by CRH (1 nmol/l) stimulation. Caprylate suppressed ACTH release in a concentration-dependent manner. However, unsaturated C18 and C20 fatty acids (oleate, linolate, linolenate and arachidonate) at 1 mmol/l significantly increased the basal release, but none of them suppressed CRH (1 nmol/l)-induced ACTH release. In the presence of caprylate (1 mmol/l), CRH (1 nmol/l)-stimulated increase in cellular calcium ion concentration was diminished. From these results we conclude that saturated fatty acids have a suppressing effect on CRH-induced ACTH increase in primary cultured rat anterior pituitary cells.

Adrenocorticotropic Hormone↗

PubMed2004

Sonoclot analysis in cardiac surgery in dialysis-dependent patients.

BACKGROUND: Dialysis-dependent patients have multiple disorders of hemostasis; however, there are no reports of viscoelastic changes during cardiac surgery in such patients. METHODS: Hemostasis in dialysis-dependent patients during cardiac operations was evaluated. Thirty patients who underwent cardiopulmonary bypass (CPB) were studied: 6 with chronic renal failure undergoing dialysis (HD group), and 24 without hemodialysis. Blood samples were obtained at four points: before sternotomy, 30 and 90 minutes after the start of CPB, and after protamine administration. RESULTS: Activated clotting time (ACT) measured with Sonoclot analyzer was significantly correlated with ACT measured traditionally (r = 0.92; p < 0.001; y = 36.1 + 0.95x). Values for ACT measured with Sonoclot analyzer as well as traditional ACT increased significantly during CPB. Values for ACT measured with Sonoclot analyzer in the HD group were significantly longer than those in the control group. Before CPB, both ACT measured with Sonoclot analyzer and traditional ACT in the HD group were significantly longer than those in the control group; however, there were no significant differences in ACT measured with Sonoclot analyzer between the groups after CPB. Clot rates and peak signal values were significantly decreased during CPB in both groups, and returned to preoperative values after protamine administration. There were no significant differences in clot rate and peak signal values between the two groups. There were no differences between the two groups in changes of time to peak. Platelet counts in the HD group were significantly higher (p < 0.05) than those in the control group. There were no differences in platelet counts after CPB between the two groups. Antithrombin III levels decreased below 50% during and after CPB. Antithrombin III in the HD group was significantly lower (p < 0.01) than those in the control group. A significant time-group interaction was observed in antithrombin III levels. CONCLUSIONS: Sonoclot signatures in HD patients showed no significant differences in viscoelastic changes compared with non-HD patients.

Cardiopulmonary Bypass↗

PubMed2004

Isolation of flavohemoglobin from the actinomycete Streptomyces antibioticus grown without external nitric oxide stress.

A flavocytochrome protein was isolated from the actinomycete Streptomyces antibioticus. The purified protein contained protoheme and FAD, and its M(r) was estimated to be 52000. The absorption spectra in its resting oxidized, dithionite-reduced, carbon monoxide-bound, and oxygenated (O(2)-bound) forms were characteristic of those of flavohemoglobin (Fhb). The N-terminal amino acid sequence showed high identities to those of other Fhb's. Furthermore, the actinomycete flavocytochrome scavenged nitric oxide in the presence of NADH. These results demonstrated that the flavocytochrome is the first Fhb purified from actinomycetes. The actinomycete Fhb was produced in S. antibioticus cells in large amounts without any external nitric oxide (NO) stress, which is indicative of a physiological function of Fhb other than detoxification of NO.

Amino Acid Sequence↗

PubMed2003

Selective synthesis and isolation of all possible conformational isomers of proximally para-disubstituted calix[4]arene.

All six possible conformational isomers of the proximally p-dibrominated calix[4]arene tetraalkyl ether, 1a-f*, were selectively synthesized by appropriate control of stereochemistry during di-O-alkylation reactions of 5,11-dibromocalix[4]arene syn-dialkyl ethers, namely, 5,11-dibromo-27,28-dihydroxy-25,26-dipropoxy-, 5,11-dibromo-25,26-dihydroxy-27,28-dipropoxy-, 5,11-dibromo-25,28-dihydroxy-26,27-propoxy-, and 5,11-dibromo-26,28-dihydroxy-25,27-dipropoxycalix[4]arenes. Their conformations were confirmed by (1)H and (13)C NMR spectroscopy and are cone for 1a (u(Br)(Pr), u(Br)(Pr), u(H)(Pr),u(H)(Pr)), partial cone for 1b (u(Br)(Pr), d(Br)(Pr), u(H)(Pr),u(H)(Pr)) and 1d (u(Br)(Pr), u(Br)(Pr), u(H)(Pr),d(H)(Pr)), 1,2-alternate for 1c (u(Br)(Pr), u(Br)(Pr), d(H)(Pr),d(H)(Pr)) and 1e (u(Br)(Pr), d(Br)(Pr), d(H)(Pr),u(H)(Pr)), and 1,3-alternate for 1f (u(Br)(Pr), d(Br)(Pr), u(H)(Pr),d(H)(Pr)). Although both 1c and 1e are in the 1,2-alternate conformation, the conformation of 1e was found to be strongly distorted and distinct from that of 1c.

Journal Article↗

PubMed2002

Codenitrification and denitrification are dual metabolic pathways through which dinitrogen evolves from nitrate in Streptomyces antibioticus.

We screened actinomycete strains for dinitrogen (N(2))-producing activity and discovered that Streptomyces antibioticus B-546 evolves N(2) and some nitrous oxide (N(2)O) from nitrate (NO(3)(-)). Most of the N(2) that evolved from the heavy isotope ([(15)N]NO(3)(-)) was (15)N(14)N, indicating that this nitrogen species consists of two atoms, one arising from NO(3)(-) and the other from different sources. This phenomenon is similar to codenitrification in fungi. The strain also evolved less, but significant, amounts of (15)N(15)N from [(15)N]NO(3)(-) in addition to (15)N(15)NO with concomitant cell growth. Prior to the production of N(2) and N(2)O, NO(3)(-) was rapidly reduced to nitrite (NO(2)(-)) accompanied by distinct cell growth, showing that the actinomycete strain is a facultative anaerobe that depends on denitrification and nitrate respiration for anoxic growth. The cell-free activities of denitrifying enzymes could be reconstituted, supporting the notion that the (15)N(15)N and (15)N(15)NO species are produced by denitrification from NO(3)(-) via NO(2)(-). We therefore demonstrated a unique system in an actinomycete that produces gaseous nitrogen (N(2) and N(2)O) through both denitrification and codenitrification. The predominance of codenitrification over denitrification along with oxygen tolerance is the key feature of nitrate metabolism in this actinomycete.

Aerobiosis↗