Emergency embolization of a ruptured pancreaticoduodenal artery aneurysm associated with the median arcuate ligament syndrome.
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Aneurysm, Ruptured↗
Biomedical subjects
Takashi Yamane
Publications and source records attributed to Takashi Yamane.
A comparative study between flow visualization and computational fluid dynamic analysis for the sun medical centrifugal blood pump.
Flow visualization experiments and computational fluid dynamic (CFD) analyses were performed and the results were compared to clarify the detailed fluid dynamic characteristics for the prototype design of a centrifugal pump, namely, an implantable ventricular assist system from Sun Medical, whose hemocompatibility was previously demonstrated in a series of animal experiments. The flow visualization was conducted with particle tracking velocimetry, and the CFD analysis was performed with STAR-CD software. The findings were as follows: (1). There were no flow separations around the curved open impeller. (2). Antithrombogenic design concepts for the inducer and the vane-shaft clearance were effective in producing axial velocity along the shaft surface and generat-ing suitable shear rates against the stationary fluid. (3). Unsteady vortex shedding in the outlet, which adversely affected the fluid dynamic efficiency, was observed clearly by flow visualization. Comparison of velocity distribution measured by flow visualization and CFD analysis showed reasonably good correlation. Our findings indicate that the impeller is suitable for an implantable artificial heart. The techniques of flow visualization and CFD analysis are complementary evaluation tools in research and development efforts.
Blood Flow Velocity↗
Flow visualization in a centrifugal blood pump with an eccentric inlet port.
Flow visualization analysis was applied to the Baylor/Miwatec centrifugal artificial heart to evaluate its fluid dynamic characteristics regarding antithrombogenicity. An eccentric vortex was found both in the upper and the lower gaps of the impeller, which is supposed to be caused by the eccentric inlet port. Therefore, one-way flow toward the outlet is formed and washes the pivot. The combination of an eccentric vortex and a pivot bearing that is washed is unique to the Baylor/Miwatec pump. For the male pivots exposed to periodic wash, the minimum shear rate around the bottom pivot was estimated to be 650/s, which is higher than the threshold for thrombus formation shown by other studies. The wall shear rate at the impeller bottom surface was found to be larger in the top contact mode than in the bottom contact mode.
Assisted Circulation↗
Resonant frequency control for artificial heart using online parameter identification.
To develop effective medical care and therapeutic control using an artificial heart, a new control method has been developed. This new method can control the artificial heart effectively and can adapt to internal physiological behavior using measured physiological data; aortic pressure, aortic flow, and pump flow. This method consists of first, a second-order physiological model, which represents the internal physiological behavior by a mathematical equation; and second, an estimation method, which can identify the physiological parameters; aortic inertia, aortic resistance, aortic compliance, and peripheral resistance by a parameter identification method. It can then calculate the resonant frequency as the control signal for the artificial heart from the identified physiological model. To confirm the effectiveness, the proposed method was evaluated in a computer simulation study. This evaluation showed that the new method could estimate the physiological parameters and the resonant frequency within a 10% error. The impedance of the systemic circulation could also be reduced by this method.
Algorithms↗
The most profitable use of flow visualization in the elimination of thrombus from a monopivot magnetic suspension blood pump.
The purpose of this study was to eliminate fluid dynamic causes of thrombus formation for the monopivot magnetic suspension centrifugal pump under development with the aid of flow visualization as an indirect measurement tool for animal experiments. The formation of thrombus observed in early animal experiments was successfully overcome by combining the multiple washout holes at the center into a single hole, optimizing the hole diameter, and eliminating the pivot gap. Flow visualization was used to optimize the washout hole diameter influencing the flow around the pivot. In animal experiments flow visualization showed that the contours of thrombus corresponded to shear rates of 300 s(-1) or 1300-1700 s(-1). It was found that flow visualization is a useful technique to predict locations where low shear thrombi form and to optimize the pump design in the development stage.
Animals↗
Effect of restraint stress on the progression of experimental periodontitis in rats.
BACKGROUND: A hypothesis of an increased risk for destructive periodontal diseases due to psychological stress has long been promoted. However, the research on stress and periodontal disease is still in its infancy. One of the reasons is thought to be that there is no suitable animal model for investigating the relationship. METHODS: One hundred male Wistar rats were included. A nylon ligature was placed around the second right maxillary molars. The animals were then divided into group S, exposed to a restraint stress for 12 hours/day for up to 10 days, and group N, controls. Ten animals were sacrificed on days 2, 4, 6, 8, and 10. Blood samples were taken, and the blood glucose level and the concentrations of adrenocorticotropic hormone, corticosterone, and adrenaline were measured as the markers of stress. The atrophies of the thymus and the spleen were measured. The furcation area of the second maxillary molars was examined histologically and histometrically. RESULTS: In group S, all values of stress markers were increased, and the thymus and the spleen were atrophied. Whereas group N showed only slight alveolar bone resorption, a marked alveolar bone resorption occurred in group S between days 8 and 10. An increase in beaded nerve terminals occurred around the vessels in the furcation area of group S. CONCLUSION: The results of the present study suggest that the restraint stress modulates the progression of periodontal inflammation and that this rat model is suitable for investigating the association between stress and periodontal disease.
Adrenocorticotropic Hormone↗
Axial type self-bearing motor for axial flow blood pump.
An axial self-bearing motor is proposed which can drive an axial blood pump without physical contact. It is a functional combination of the bi-directional disc motor and the axial active magnetic bearing, where it actively controls single degree-of-freedom motion, while other motions such as lateral vibration are passively stable. For application to a blood pump, the proposed self-bearing motor has the advantages of simple structure and small size. Through the finite element method (FEM) analysis and the experimental test, its good feasibility is verified. Finally, the axial flow pump is fabricated using the developed magnetically suspended motor. The pump test is carried out and the results are discussed in detail.
Equipment Design↗
Tsukuba remote monitoring system for continuous-flow artificial heart.
In order to make long-term medical treatment with the use of an artificial heart effective, we developed the Tsukuba remote monitoring system, which enables medical staff to manage the physiological condition of patients and the driving condition of the artificial heart at anytime from a remote place. This remote monitoring system has three functions: first, a remote monitoring function, which enables medical staff to monitor measured data from a remote place anytime by using not only a personal computer but also a cellular phone; second, an analyzing function, which estimates the unmeasured physiological behavior in the body based on a mathematical physiological model; and third, a warning function, which detects physiological problems and malfunction of the artificial heart by applying the if-then rule and sends a warning message to the medical staff. As a result of applying this system to animal experiments, we have confirmed the effectiveness of the proposed system.
Animals↗
Different levels of TIMPs and MMPs in human lateral and medial rectus muscle tissue excised from strabismic patients.
PURPOSE: To arrive at an understanding of the differences in gene and protein expression between human lateral and medial rectus muscle tissue excised from strabismic patients. METHODS: Resected fragments of the lateral and medial rectus muscles obtained during strabismus surgery were frozen under liquid nitrogen and pulverized by a Freezer/Mill system. Radiolabelled cDNA was synthesized from polyA+ RNA and hybridized with a gene array nylon membrane (Atlas Human 1.2 Array) to detect the difference in gene expression between the lateral and medial rectus muscles. Based on the gene array results, tissue inhibitor of metalloproteinases (TIMP)-1 and 2, matrix metalloproteinase (MMP)-2, and bone morphogenetic protein (BMP)-4 were measured in solubilized muscle tissues by enzyme immunoassay and normalized by unit length of resection. RESULTS: The resected lateral rectus muscle had significantly smaller amounts of TIMP-1, TIMP-2 and BMP-4 but larger amounts of MMP-2 compared to the medial rectus muscle (P < 0.001, Mann-Whitney U test). The amounts of TIMP-1 in the muscle when the lateral and medial rectus were combined were positively correlated with TIMP-2 and BMP-4, while the amounts of TIMP-2 positively correlated with BMP-4 (P < 0.001, Spearman rank correlation test). The amounts of BMP-4 in both muscles increased significantly with age (P = 0.0003). CONCLUSIONS: Resected tissue from the lateral and medial rectus muscles had different levels of expression of TIMP-1 and 2, MMP-2, and BMP-4. These molecular differences may underlie different characteristics of the two extraocular muscles and may also influence the process of wound healing after strabismus surgery.
Adolescent↗
An empirical approach for structure-based prediction of carbohydrate-binding sites on proteins.
A computer program system was developed to predict carbohydrate-binding sites on three-dimensional (3D) protein structures. The programs search for binding sites by referring to the empirical rules derived from the known 3D structures of carbohydrate-protein complexes. A total of 80 non-redundant carbohydrate-protein complex structures were selected from the Protein Data Bank for the empirical rule construction. The performance of the prediction system was tested on 50 known complex structures to determine whether the system could detect the known binding sites. The known monosaccharide-binding sites were detected among the best three predictions in 59% of the cases, which covered 69% of the polysaccharide-binding sites in the target proteins, when the performance was evaluated by the overlap between residue patches of predicted and known binding sites.
Animals↗
Clinical correlations of aggrecan in the resected medial rectus muscle of patients with intermittent exotropia.
The purpose of this study was to elucidate the role of extracellular matrix components such as aggrecan, fibronectin, and laminin in the extraocular muscle of patients with strabismus. Resected tissues of the medial rectus muscle of 47 patients with intermittent exotropia obtained during recession-resection surgery were frozen under liquid nitrogen and pulverized by a Freezer/Mill to solubilize the tissue for enzyme immunoassay. The total amounts of aggrecan, fibronectin, and laminin in the resected tissue were correlated with clinical data of patients such as age, exodeviation, and refractive error. The amount of aggrecan decreased significantly with the advance of age (P < 0.0001, Spearman rank correlation test), while the amount of laminin or fibronectin had no correlation with age. Patients with basic type intermittent exotropia showed larger, although not significantly, amounts of aggrecan than those with convergence insufficiency type (P = 0.0538, Mann-Whitney U-test). The amount of aggrecan may be related to motor aspects of intermittent exotropia.
Adolescent↗
Genome-wide search for strabismus susceptibility loci.
The purpose of this study was to search for chromosomal susceptibility loci for comitant strabismus. Genomic DNA was isolated from 10mL blood taken from each member of 30 nuclear families in which 2 or more siblings are affected by either esotropia or exotropia. A genome-wide search was performed with amplification by polymerase chain reaction of 400 markers in microsatellite regions with approximately 10 cM resolution. For each locus, non-parametric affected sib-pair analysis and non-parametric linkage analysis for multiple pedigrees (Genehunter software, http://linkage.rockefeller.edu/soft/) were used to calculate multipoint lod scores and non-parametric linkage (NPL) scores, respectively. In sib-pair analysis, lod scores showed basically flat lines with several peaks of 0.25 on all chromosomes. In non-parametric linkage analysis for multiple pedigrees, NPL scores showed one peak as high as 1.34 on chromosomes 1, 2, 4, 7, 10, 15, and 16, while 2 such peaks were found on chromosomes 3, 9, 11, 12, 18, and 20. Non-parametric linkage analysis for multiple pedigrees of 30 families with comitant strabismus suggested a number of chromosomal susceptibility loci. Our ongoing study involving a larger number of families will refine the accuracy of statistical analysis to pinpoint susceptibility loci for comitant strabismus.
Adolescent↗
[Serum amyloid A as a useful index of disease activity in polymyalgia rheumatica].
PURPOSE: To clarify the usefulness of measuring serum amyloid A (SAA) levels in patients with polymyalgia rheumatica (PMR), we compared this parameter to C-reactive protein (CRP). SUBJECTS AND METHODS: The study included 10 patients with PMR, who could be prospectively followed up from the start of prednisolone (PSL) treatment until the CRP level decreased to 1 mg/dl or less. When the CRP level decreased, the subjects were divided into the group in which the symptom persisted (n = 6) and those in which the symptom disappeared (n = 4). RESULTS: In the group in which the symptom persisted, both CRP and SAA levels were significantly higher. When the CRP level decreased, there was no significant difference in the CRP level between the two groups. However, the mean SAA level in the group in which the symptom persisted (137.8 micrograms/ml) was significantly higher than that in the group in which the symptom disappeared (21.8 micrograms/ml). On the initial consultation, there was a positive correlation between CRP and SAA (R = 0.77). The SAA level was more sensitive than the CRP level (y = 94.899 x -51.22). When the CRP level decreased, SAA was much more sensitive (y = 222.92 x +6.9121), suggesting the usefulness of SAA after the start of PSL treatment. CONCLUSION: SAA may be a useful parameter of PMR activity.
Aged↗
Crystal structure of a conger eel galectin (congerin II) at 1.45A resolution: implication for the accelerated evolution of a new ligand-binding site following gene duplication.
The crystal structure of congerin II, a galectin family lectin from conger eel, was determined at 1.45A resolution. The previously determined structure of its isoform, congerin I, had revealed a fold evolution via strand swap; however, the structure of congerin II described here resembles other prototype galectins. A comparison of the two congerin genes with that of several other galectins suggests acceralated evolution of both congerin genes following gene duplication. The presence of a Mes (2-[N-morpholino]ethanesulfonic acid) molecule near the carbohydrate-binding site in the crystal structure points to the possibility of an additional binding site in congerin II. The binding site consists of a group of residues that had been replaced following gene duplication suggesting that the binding site was built under selective pressure. Congerin II may be a protein specialized for biological defense with an affinity for target carbohydrates on parasites' cell surface.
Alkanesulfonic Acids↗
Enzymatic properties, crystallization, and deduced amino acid sequence of an alkaline endoglucanase from Bacillus circulans.
A high-isoelectric-point (pI), alkaline endo-1,4-beta-glucanase (Egl-257) of Bacillus circulans KSM-N257 was purified to homogeneity and crystallized. The purified enzyme hydrolyzed carboxymethyl cellulose (CMC) with optima of pH 8.5 and 55 degrees C. The molecular mass was 43 kDa, and the pI was pH 9.3. The structural gene contained a single open reading frame of 1221 bp, corresponding to 407 amino acids (aa), including a 30-aa signal peptide (377 aa and 41,680 Da for the mature enzyme). Egl-257 hydrolyzed lichenan and showed 76.3% aa identity to a lichenase from B. circulans WL-12 belonging to glycosyl hydrolase family 8 but did not hydrolyze laminarin, curdran, and xylan at all. This indicates that Egl-257 is a true endo-1,4-beta-glucanase. However, this enzyme was not active on p-nitrophenyl beta-D-cellotrioside and p-nitrophenyl beta-D-cellotetraoside. It was crystallized by the hanging-drop vapor-diffusion method with phosphate plus CdCl(2) as precipitant. Pyramid-like crystals were formed, and they diffracted X-rays beyond 2.2 A resolution. It belongs to the space group P2(1)2(1)2(1) with unit cell parameters of a=62.5 A, b=71.7 A, and c=88.6 A.
Amino Acid Sequence↗
Upward shift of the pH optimum of Acremonium ascorbate oxidase.
A gene encoding a thermostable Acremonium ascorbate oxidase (ASOM) was randomly mutated to generate mutant enzymes with altered pH optima. One of the mutants, which exhibited a significantly higher activity in the pH range 4.5-7 compared to ASOM, had a Gln183Arg substitution in the region corresponding to SBR1, one of the substrate binding regions of the zucchini enzyme. The other mutant with almost the same pH profile as Gln183Arg had a Thr527Ala substitution near the type 3 copper center and became more sensitive to azide than ASOM. Site-directed mutagenesis in the substrate binding regions with reference to the amino acid sequences of plant enzymes led to isolation of mutants shifted upward in the pH optimum; Val193Pro and Val193Pro/Pro190Ile increased the pH optimum by 1 and 0.5 units, respectively, while retaining the near-wild-type thermostability and azide sensitivity. The homology model of ASOM constructed from the zucchini enzyme coordinates suggested that replacement of Val193 by Pro could disturb the ion pair networks among Arg309, Glu192, Arg194 and Glu311. This perturbation could affect either the molecular recognition between the substrate and ASOM or the electron transfer from the substrate to the type 1 copper center, leading to the alkaline shift of the catalytic activity of the mutant enzyme. The other mutations, Val193Pro/Pro190Ile, could also induce similar structural perturbations involving the ion pair networks.
Acremonium↗
The speciation of conger eel galectins by rapid adaptive evolution.
Many cases of accelerated evolution driven by positive Darwinian selection are identified in the genes of venomous and reproductive proteins. This evolutional phenomenon might have important consequences in their gene-products' functions, such as multiple specific toxins for quick immobilization of the prey and the establishment of barriers to fertilization that might lead to speciation, and in the molecular evolution of novel genes. Recently, we analyzed the molecular evolution of two galectins isolated from the skin mucus of conger eel (Conger myriaster), named congerins I and II, by cDNA cloning and X-ray structural analysis, and we found that they have evolved in the rapid adaptive manner to emergence of a new structure including strand-swapping and a unique new ligand-binding site. In this review article we summarize and discuss the molecular evolution, especially the rapid adaptive evolution, and the structure-function relationships of conger eel galectins.
Animals↗
On-line parameter identification of systemic circulation using the delta operator.
To develop effective medical care with the artificial heart, we propose a new method, on-line parameter identification of the systemic circulation using the delta operator which can calculate the time-varying and unmeasured hemodynamics of the internal human body from some measured data: aortic pressure and total flow in real time. This method consists of first, a dynamic physiological model which is configured with the physiological parameters Ca (aortic compliance) and Rp (total peripheral resistance); and second, a system identification method using the delta operator. In the computer simulation study, we could confirm the effectiveness to identify the physiological parameters. In animal experiments with a left ventricular assist system, the physiological parameters, Ca = 1.8 (ml/mm Hg) and Rp = 0.8 (mm Hg s/ml), could be identified on-line.
Adaptation, Physiological↗