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Biomedical subjects

H Akimoto

Publications and source records attributed to H Akimoto.

At least 55 records · Page 3Linked to original sources
PubMed2001

First measurement of the ratio B(t --> Wb)/B(t --> Wq) and associated limit on the Cabibbo-Kobayashi-Maskawa element /V(tb)/.

We present the first measurement of the ratio of branching fractions R identical withB(t-->Wb)/B(t-->Wq) from p_p collisions at sqrt[s] = 1.8 TeV. The data set corresponds to 109 pb(-1) of data recorded by the Collider Detector at Fermilab during the 1992-95 Tevatron run. We measure R = 0.94(+0.31)(-0.24)(stat+syst) or R>0.61 (0.56) at 90% (95)% C.L., in agreement with the standard model predictions. This measurement yields a limit on the Cabibbo-Kobayashi-Maskawa quark mixing matrix element /V(tb)/ under the assumption of three generations and unitarity.

Journal Article↗
PubMed2001

Improved direct measurement of leptonic coupling asymmetries with polarized Z bosons.

We present final measurements of the Z boson-lepton coupling asymmetry parameters A(e), A(mu), and A(tau) with the complete sample of polarized Z bosons collected by the SLD detector at the SLAC Linear Collider. From the left-right production and decay polar angle asymmetries in leptonic Z decays we measure A(e) = 0.1544+/-0.0060, A(mu) = 0.142+/-0.015, and A(tau) = 0.136+/-0.015. Combined with our left-right asymmetry measured from hadronic decays, we find A(e) = 0.1516+/-0.0021. Assuming lepton universality, we obtain a combined effective weak mixing angle of sin (2)theta(eff)(W) = 0.230 98+/-0.000 26.

Journal Article↗
PubMed2001

First symmetry tests in polarized Z0 decays to bbg.

We have made the first direct symmetry tests in the decays of polarized Z0 bosons into fully identified bbg states, collected in the SLD experiment at SLAC. We searched for evidence of parity violation at the bbg vertex by studying the asymmetries in the b-quark polar- and azimuthal-angle distributions, and for evidence of T-odd, CP-even or CP-odd, final-state interactions by measuring angular correlations between the three-jet plane and the Z0 polarization. We found results consistent with standard model expectations and set 95% C. limits on anomalous contributions.

Journal Article↗
PubMed2001

Cryopreserved aortic homograft replacement in 3 patients with noninfectious inflammatory vascular disease.

OBJECTIVE: Although mechanical prosthetic heart valves are most commonly used for aortic valve replacement in patients with aortic regurgitation due to noninfectious inflammatory vascular disease, postoperative perivalvular leakage and/or detachment of the prosthetic valve occurs due to the fragility of the aortic annulus. Aortic root replacement with cryopreserved homografts is reported to be useful in such patients. METHODS: Three patients having aortic regurgitation associated with severe long standing noninfectious inflammatory vascular disease-2 patients with Takayasu's arteritis and 1 patient with Behçet disease--had the aortic root replacement by a cryopreserved aortic homograft valve and conduit. RESULTS: All surgery was successful and the postoperative course uneventful. Echocardiography showed neither aortic regurgitation nor graft detachment at 6-39 months after operation. CONCLUSIONS: Homograft valve and conduit replacement is appropriate in patients with aortic regurgitation associated with noninfectious inflammatory vascular disease, with mid-term results favorable.

Adult↗
PubMed2001

Concomitant replacement of the aortic root and aortic arch with or without secondary thoracoabdominal aorta replacement.

OBJECTIVES: Extensive aortic replacement, such as concomitant aortic root and arch replacement, thoracoabdominal aortic repair, and complete thoracic aorta replacement, remains controversial. We studied surgical morbidity and mortality in patients undergoing concomitant aortic root and arch replacement, and those undergoing secondary replacement of the thoracoabdominal aorta after this preceding procedure. SUBJECTS AND METHODS: Between January, 1987 and March 1999, 21 patients (mean age: 52 years) underwent concomitant aortic root and arch replacement involving 3 surgical procedures--aortic root replacement with composite graft and arch (n = 12), aortic root replacement with valve sparing and arch (n = 4), or aortic root replacement with composite graft and arch and elephant trunk (n = 5). RESULTS: Overall hospital mortality was 4.8%. Six patients (mean age: 42 years) underwent secondary thoracoabdominal aorta replacement after the concomitant root and arch procedure. The mean time until secondary surgery was 9.5 months. There was 1 hospital death. CONCLUSION: Concomitant replacement of the aortic root and arch, or secondary replacement of the thoracoabdominal aorta after concomitant root and arch replacement can be conducted with low surgical morbidity and mortality.

Adolescent↗
PubMed2001

Tuberous sclerosis: epileptogenicity and multimodal presurgical evaluations.

We report on a patient with tuberous sclerosis-related epilepsy who benefited from surgical treatment. Various presurgical evaluations, including positron emission tomography (PET), made it possible for us to localize the epileptic focus accurately. In this paper, we stress the importance of performing multimodal evaluations to determine which tubers really possess epileptogenicity. In addition, the implications of PET in tuberous sclerosis-related epilepsy are described.

Cerebral Cortex↗
PubMed2001

Commissure holder: an innovative device for aortic valve-sparing technique.

The key to obtaining maximal valve coaptation from the aortic valve-sparing procedure is in appreciating the optimal geometry of each component of the aortic root. We describe a new device called the Commissure Holder (patent pending) that aids in the selection of an appropriate graft size and in the determination of the optimal position at which each commissure should be sutured to the graft.

Aorta, Thoracic↗
PubMed2001

Successful management of secondary aortoesophageal fistula with graft infection.

A 60-year-old woman was transferred to our institution after massive hematemesis and the diagnosis of secondary aortoesophageal fistula was made. Five months previously, she had undergone graft replacement from the origin of the left subclavian artery to midthoracic aorta for chonic type B dissection. After an extraanatomic bypass was performed through a sternotomy, the infected thoracic aortic graft was resected through a left thoracotomy. She remained well without evidence of infection.

Aortic Dissection↗
PubMed2001

Pyrrolo[2,3-d]pyrimidine thymidylate synthase inhibitors: design and synthesis of one-carbon bridge derivatives.

A series of novel pyrrolo[2,3-d]pyrimidine derivatives was designed and synthesized as thymidylate synthase (TS) inhibitors. Molecular design was performed on the human TS complex model built on the basis of the reported structure of TS-deoxyuridinemonophosphate (dUMP)-CB3717 ternary complex. From a docking study, we expected that a one-carbon bridge between pyrrolo[2,3-d]pyrimidine and an aromatic ring was suitable. Moreover, we found that the bridge carbon could be replaced with an alkyl group to fill out the unoccupied space. Based on this design, we synthesized five pyrrolo[2,3-d]pyrimidine derivatives with one-carbon bridge and evaluated their TS inhibitory activities. All synthesized compounds inhibited TS more potently than compound 2 (LY231514), and the C8-ethyl analogue (7) showed a remarkable inhibitory activity against TS (IC50=0.017 microM).

Amino Acid Sequence↗
PubMed2001

Purification and characterization of an acidophilic xylanase from Aureobasidium pullulans var. melanigenum and sequence analysis of the encoding gene.

An extracellular endo-1,4-beta-xylanase was purified from the culture supernatant of Aureobasidium pullulans var. melanigenum (ATCC 20524) grown on oat-spelt xylan. The purified enzyme showed a single band on SDS-polyacrylamide gel electrophoresis with an apparent M(r) of 24 kDa and had an isoelectric point of 6.7. Xylanase activity was optimal at pH 2.0 and 50 degrees C. The genomic DNA and cDNAs encoding this protein were cloned and sequenced. Southern blot analysis indicated that the xylanase gene (xynI) was present as a single copy in the genome. An open reading frame, consisting of 663 bp, encoded a presumed prepropeptide of 34 amino acids and a mature protein of 187 amino acid. The DNA region encoding the prepeptide was interrupted by a 59-bp intron. A single transcription start point was observed at position -46 (A) from the start codon. The 5'-noncoding region had a putative TATA box at -91 (TATATAA) and two possible CCAAT boxes at -247 (CAAT) and -283 (CCAAT). A cloned xynI cDNA was expressed in Saccharomyces cerevisiae. The deduced amino acid sequence showed 94% identity with that of a previously reported equivalent gene (xynA) encoding a xylanase with an optimal pH of 4.8 from a color variant strain, NRRL Y-2311-1, of A. pullulans. A neighbor-joining tree showed that the Aureobasidium enzymes are closely related to several other family-11 xylanases from black aspergilli and Penicillium purpurogenum.

Journal Article↗
PubMed2001

[Aortic root replacement after operation for the ascending aorta and/or aortic valve].

We reviewed ten cases who underwent aortic root replacement after operation for the ascending aorta and/or aortic valve. As initial operation, aortic valve replacement (AVR) was performed in five patients, replacement of the ascending aorta in two, original Bentall operation in two, and entry closure and suspension of the aortic valve in one. At reoperation, three patients were diagnosed as aneurysm of the ascending aorta, two were annulo-aortic ectasia, and one was acute aortic dissection, chronic dissecting aneusym, pseudoaneurysm of the ascending aorta, prosthetic valve endocarditis, and massive aortic regurgitation. Aortic root replacement was performed using mechanical valved composite graft in all cases. One patient who underwent repeat aortic root replacement for prosthetic valve endocarditis was died of septemia and ventricular fibrillation. Five patients had nine complications (two low output syndrome, respiratory failure and cerebral infarction, one gastrointestinal bleeding, septemia and ventricular fibrillation). In conclusion, aortic root replacement after operation for the ascending aorta and/or aortic valve was performed with acceptable morbidity and mortality.

Adult↗
PubMed2001

[Efficacy of modified ultrafiltration in reoperation for valvular disease].

We evaluated the efficacy of modified ultrafiltration (MUF) in reoperation for valvular disease. Fourteen patients were divide into two groups consisting of a control group (n = 6) and a MUF group (n = 8). MUF was carried out for fifteen minutes immediately after the completion of cardiopulmonary bypass. The blood flow through the ultrafilter was 300 ml/min and about 1,200 ml of water was removed. The hematocrit elevated significantly from 25% to 31% in the MUF group (p < 0.05). The percentage of the increase in body weight after the operation in the MUF group was significantly less than that in the control group (3.3 +/- 3.1% vs 8.3 +/- 4.3%, p < 0.05). The PaO2/FIO2 after the operation in the MUF group was significantly higher than that in the control group (376 +/- 125 mmHg vs 242 +/- 79 mmHg, p < 0.05). The duration of mechanical ventilation in the MUF group was significantly less than that in the control group (1.1 +/- 1.1 days vs 5.3 +/- 3.3 days, p < 0.05). In conclusion, MUF is useful to hemoconcentrate, reduce postoperative body weight gain and promote early recovery of pulmonary function in reoperation for valvular disease.

Aged↗
PubMed2001

[Efficacy of modified ultrafiltration in coronary artery bypass grafting].

We evaluated the efficacy of modified ultrafiltration (MUF) in coronary artery bypass grafting. Twenty patients were divide into two groups consisting of a control group (n = 11) and a MUF group (n = 9). MUF was carried out for fifteen minutes immediately after the completion of cardiopulmonary bypass. The blood flow through the ultrafilter was 300 ml/min and about 1,200 ml of water was removed. The hematocrit elevated significantly from 25% to 30% in the MUF group (p < 0.01). Postoperative blood loss in the first 24 hours in the MUF group was significantly less than that in the control group (8 +/- 2 ml/kg vs 12 +/- 4 ml/kg, p < 0.01). There was no statistical difference in the percentage of the increase in body weight after the operation, inflammatory reaction and pulmonary function (A-a DO2, PaO2/FIO2 and duration of intubation) between two groups. In conclusion, MUF is useful to hemoconcentrate and reduce postoperative blood loss in coronary artery bypass grafting.

Aged↗
PubMed2000

Measurement of J/psi and psi(2S) polarization in pp collisions at sqrt[s] = 1.8 TeV.

We have measured the polarization of J/psi and psi(2S) mesons produced in pp collisions at sqrt[s] = 1.8 TeV, using data collected at the Collider Detector at Fermilab during 1992-1995. The polarization of promptly produced J/psi [psi(2S)] mesons is isolated from those produced in B-hadron decay, and measured over the kinematic range 4 [5.5]<P(T)<20 GeV/c and |y|<0.6. For P(T) greater than or approximately equal 12 GeV/c we do not observe significant polarization in the prompt component.

Journal Article↗
PubMed2000

Melting process and interface instability of highly magnetized solid 3He: role of the magnetization gradient

We elucidate the melting process of highly magnetized solid 3He by observing the magnetization profile and the liquid-solid interface simultaneously. Clear enhancements of magnetization and magnetization gradients at the interface of both the solid and the liquid were observed during melting. These measurements provide a mesoscopic confirmation of the melting scenario of Castaing and Nozieres, and explain the long delay before the instability sets in: The magnetization gradient in the liquid leads to an initial suppression of the melting instability, in accordance with our extension of the stability analysis of Puech et al. This resolves the discrepancy between theory and experiment.

Journal Article↗
PubMed2000

4'-Hydroxy aceclofenac suppresses the interleukin-1-induced production of promatrix metalloproteinases and release of sulfated-glycosaminoglycans from rabbit articular chondrocytes.

This study demonstrates the novel actions of a non-steroidal anti-inflammatory drug aceclofenac, which is frequently used for rheumatoid arthritis and osteoarthritis. 4'-Hydroxy aceclofenac, a main metabolite of aceclofenac in humans, down-regulated the production of promatrix metalloproteinase-1/procollagenase 1 and promatrix metalloproteinase-3/prostromelysin 1 along with a decrease in their mRNAs in rabbit articular chondrocytes and synoviocytes, and interfered with the release of sulfated-glycosaminoglycans (proteoglycans) from the chondrocytes. 4'-Hydroxy aceclofenac also suppressed the proliferation of rabbit synoviocytes. In contrast, aceclofenac itself and its other metabolites, diclofenac and 4'-hydroxy declofenac, did not exert obvious actions on cellular functions. Therefore, it is suggested that the therapeutic effects of aceclofenac on rheumatoid arthritis and osteoarthrits are, at least in part, due to the novel chondroprotective effect of 4'-hydroxy aceclofenac via the suppression of promatrix metalloproteinase production and proteoglycan release. There is also evidence that inhibition of synoviocyte proliferation and the known inhibitory action on prostaglandin E(2) production play a role.

Animals↗
PubMed2000

High-precision measurement of the left-right Z Boson cross-section asymmetry.

We present a measurement of the left-right cross-section asymmetry ( A(LR)) for Z boson production by e(+)e(-) collisions. The measurement includes the final data taken with the SLD detector at the SLAC Linear Collider during the period 1996-1998. Using a sample of 383 487 Z decays collected during the 1996-1998 runs we measure the pole value of the asymmetry, A(0)(LR), to be 0.150 56+/-0.002 39 which is equivalent to an effective weak mixing angle of sin (2)straight theta(eff)(W) = 0.231 07+/-0.000 30. Our result for the complete 1992-1998 data set comprising approximately 537 000 Z decays is sin (2)straight theta(eff)(W) = 0.230 97+/-0.000 27.

Journal Article↗