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Biomedical subjects

S Akita

Publications and source records attributed to S Akita.

At least 19 recordsLinked to original sources
PubMed2006

Combined injuries of the brachial plexus and spinal cord.

A total of 11 patients with combined traumatic injuries of the brachial plexus and spinal cord were reviewed retrospectively. Brachial plexus paralysis in such dual injuries tends to be diagnosed and treated late and the prognosis is usually poor. The associated injuries, which were all on the same side as the plexus lesion, were to the head (nine cases), shoulder girdle (five), thorax (nine) and upper limb (seven). These other injuries were responsible for the delayed diagnosis of brachial plexus paralysis and the poor prognosis was probably because of the delay in starting treatment and the severity of the associated injuries. When such injuries are detected in patients with spinal cord trauma, it is important to consider the possibility of involvement of the brachial plexus.

Accidents↗
PubMed2005

Hydrometallurgical recovery of zinc from ashes of automobile tire wastes.

Study has been performed on the investigation of metal leaching behavior for fly and bottom ashes from automobile tire wastes using acid and alkaline solutions from both viewpoints of environmental protection and resource utilization. The two ashes were found to contain substantial amounts of zinc and iron along with small quantities of cobalt, manganese, magnesium, copper, titanium and aluminum. The fly ash contained a much larger amount of zinc than the bottom ash, and seems to be a promising secondary source for the metal. Effects of such experimental parameters as temperature, time and solid-liquid ratio on the leaching behavior were investigated. Using three mineral acids and citric acid, selective leaching of zinc was successfully attained; the concentration of zinc in the leach liquors from the fly ash reached as high as 20 g l(-1) while the iron leaching was much suppressed. Selective separation of zinc was also attained in the leaching with alkaline solutions, though the percent leaching was lower than that in the acid leaching. Moreover, solvent extraction and precipitation were applied to the metal-loaded leach liquors as downstream processing to evaluate the feasibility of zinc recovery.

Acids↗
PubMed2005

Human mesenchymal stem cells successfully improve skin-substitute wound healing.

BACKGROUND: Large or deteriorated skin defects are sometimes life threatening. There is increasing evidence that adult stem cells are useful for tissue regeneration. Human mesenchymal stem cells (hMSCs) are self-renewing and are potent in differentiating into multiple cells and tissues. OBJECTIVES: To investigate the effects of hMSCs in cutaneous wound healing. METHODS: Wound healing was studied in an hMSC-populated porcine skin substitute, using a nude rat model to minimize immune reactions. Full-thickness skin and soft tissue defects of 1.5 x 1.5 cm in size, including the panniculus carnosus, were excised and covered with hMSCs and basic fibroblast growth factor (bFGF)-soaked skin substitutes and an evaluation was made of wound size, histology and protein expression at 3, 7 and 42 days after injury. RESULTS: The wound size was significantly smaller in the hMSC-treated groups (P < 0.01) and any dose of bFGF (1, 10, 100 microg) enhanced the healing (P < 0.01). The re-epithelialization markers integrin alpha3 and skin-derived antileucoproteinase were remarkably increased with the presence of bFGF in a dose-dependent manner, while the mesenchymal cell surface markers CD29 and CD44 were downregulated in a time-dependent manner. Human pancytokeratin, which does not cross-react with rat antigens, was observed by Western blotting at 38 kDa and 42 kDa from the hMSC-treated tissues on day 7. The expression levels were elevated by 10 microg bFGF (P < 0.01). The immunohistochemical expression of human pancytokeratin was only observed in the hMSC-treated groups. CONCLUSIONS: These data suggest that hMSCs together with bFGF in a skin defect model accelerate cutaneous wound healing as the hMSCs transdifferentiate into the epithelium.

Animals↗
PubMed2002

Striking effect of left ventricular high filling pressure with mitral regurgitation on mitral annular velocity during early diastole. A study using colour M-mode tissue Doppler imaging.

AIMS: To evaluate the effect of considerably high left ventricular filling pressure with mitral regurgitation on mitral annular velocity during early diastole. SUBJECTS: Two hundred and forty-three patients who underwent cardiac catheterization for evaluation of chest pain. METHODS: Mitral annular velocity during early diastole was measured by colour M-mode tissue Doppler imaging. Patients were divided into the following three groups according to the cardiac catheterization data. Group A (n=147): patients having left ventricular relaxation time constant tau<46 ms and left ventricular end-systolic volume index <38 ml m(-2); group B (n=88): patients having tau>or=46 ms and/or end-systolic volume index >or=38 ml m(-2); group C (n=8): patients having mean pulmonary capillary wedge pressure >or=16 mmHg in addition to tau>or=46 ms and end-systolic volume index >or=38 ml m(-2). RESULTS: Mitral annular velocity during early diastole was significantly less in group B (4.8+/-1.4 cm s(-1)) than in group A (7.7+/-1.9 cm s(-1)). However, there was no significant difference between groups A and C (8.3+/-0.8 cm s(-1)). A transmitral E/A >1.0 was observed in 12/147 patients of group A, 10/88 of group B, and 8/8 of group C. The incidence of >or=Sellers' grade II mitral regurgitation was higher in group C than the others. CONCLUSIONS: A paradoxically faster mitral annular velocity during early diastole is found in patients having left ventricular dysfunction with moderate to severe mitral regurgitation and considerably high left ventricular filling pressure. Attention should be paid to an interpretation of mitral annular velocity during early diastole regarding left ventricular early diastolic performance in patients having mitral regurgitation with an E/A >1.0 in their transmitral flow.

Blood Flow Velocity↗
PubMed2001

Selective concentration of gold in water to a polystyrene-embedded fiber disk with polyoxyethylene(10)-p-isononylphenyl ether.

A new surfactant-mediated separation method was developed for concentrating traces of gold ion in water. The methodology is based on the combination of selective complexation of gold(III) with polyoxyethylene(10)-p-isononylphenyl ether, PONPE-10, and strong binding of surfactant complex to hydrophobic polystyrene resins embedded in a PTFE fiber disk (Empore disk). A 400-fold concentration of gold(III) was achieved by 400 ml load of the sample containing 0.01% (w/v) PONPE-10 and 0.10 M nitric acid and by the subsequent elution with 1.0 ml of aqueous buffer solution of 0.01 M N-(dithiocarboxyl)sarcosine diammonium. Traces of gold (0.40 ng/l) in river water samples were successfully determined with inductively coupled plasma MS.

Ethers↗
PubMed2001

The profibrinolytic enzyme subtilisin NAT purified from Bacillus subtilis Cleaves and inactivates plasminogen activator inhibitor type 1.

In this report, we demonstrate an interaction between subtilisin NAT (formerly designated BSP, or nattokinase), a profibrinolytic serine proteinase from Bacillus subtilis, and plasminogen activator inhibitor 1 (PAI-1). Subtilisin NAT was purified to homogeneity (molecular mass, 27.7 kDa) from a saline extract of B. subtilis (natto). Subtilisin NAT appeared to cleave active recombinant prokaryotic PAI-1 (rpPAI-1) into low molecular weight fragments. Matrix-assisted laser desorption/ionization in combination with time-of-flight mass spectroscopy and peptide sequence analysis revealed that rpPAI-1 was cleaved at its reactive site (P1-P1': Arg(346)-Met(347)). rpPAI-1 lost its specific activity after subtilisin NAT treatment in a dose-dependent manner (0.02-1.0 nm; half-maximal effect at approximately 0.1 nm). Subtilisin NAT dose dependently (0.06-1 nm) enhanced tissue-type plasminogen activator-induced fibrin clot lysis both in the absence of rpPAI-1 (48 +/- 1.4% at 1 nm) and especially in the presence of rpPAI-1 (78 +/- 2.0% at 1 nm). The enhancement observed in the absence of PAI-1 seems to be induced through direct fibrin dissolution by subtilisin NAT. The stronger enhancement by subtilisin NAT of rpPAI-1-enriched fibrin clot lysis seems to involve the cleavage and inactivation of active rpPAI-1. This mechanism is suggested to be important for subtilisin NAT to potentiate fibrinolysis.

Bacillus subtilis↗
PubMed2001

Striking effect of left ventricular systolic performance on propagation velocity of left ventricular early diastolic filling flow.

Propagation velocity of left ventricular (LV) early diastolic filling flow (PVE) has been acknowledged as a useful parameter for LV early diastolic performance; however, the effect of LV systolic performance on PVE is not fully understood. Thus the purpose of this study was to investigate such an effect. Propagation of LV early diastolic filling flow was visualized by M-mode color Doppler imaging, and the slopes of the peak velocity tracings were measured as PVE in 150 patients who underwent coronary angiography. In cardiac catheterization, mean pulmonary capillary wedge pressure, time constant tau of LV pressure decay, LV end-systolic volume index, and LV ejection fraction were obtained. In univariate regression analysis, PVE significantly correlated with LV end-systolic volume index (r = -0.68, P <.001), LV ejection fraction (r = 0.66, P <.001), and time constant tau (r = -0.52, P <.001). In multivariate regression analysis, PVE was regressed by the LV end-systolic volume index, tau, and mean pulmonary capillary wedge pressure. The contribution of each parameter to the variance of the PVE was 46%, 3%, and 2%, respectively. A break-point linear regression analysis showed that the relation between the LV end-systolic volume index and PVE was much better characterized by a broken line than a straight line. The broken line had a steeper slope in patients with LV end-systolic volume index < or =41 mL/m(2) than in those with >41 mL/m(2). These findings suggest that PVE is determined mainly by LV systolic performance and partly by both LV relaxation and LV filling pressure. Left ventricular systolic performance may play a key role in generating a much faster PVE, especially in patients with relatively better LV systolic performance.

Aged↗
PubMed2001

Acid stimulates E-cadherin surface expression on gastric epithelial cells to stabilize barrier functions via influx of calcium.

BACKGROUND AND AIMS: E-cadherin, which is a [Ca2+]-dependent, homotypic cell-cell adhesion molecule, is expressed in gastrointestinal epithelial cells. Much has been learned about the down-regulation of E-cadherin expression in gastrointestinal tumours, Barrett's oesophageal dysplasia, and Crohn's disease, but the functions of this molecule in normal gastrointestinal mucosa are less known. METHODS: In this study, we investigated the relationship between E-cadherin expression and permeability using rat cultured gastric and intestinal epithelial cells following a 30-min exposure to various pH solutions. We also investigated the participation of [Ca2+] in these events. RESULTS: E-cadherin expression increased under acid (pH 4) but not alkali (pH 10 or 11) exposure only for gastric epithelial cells. Gastric epithelial permeability was maintained only against acid exposure while intestinal permeability increased under both conditions. Transient influx of [Ca2+] was only observed for gastric epithelial cells just after acid exposure. CONCLUSIONS: These findings suggest that E-cadherin expression on gastric epithelium stabilizes the epithelial barrier against acid, probably through influx of [Ca2+]. This event is thought to be one of the protective mechanisms in gastric mucosa against acid back-diffusion, which is one of the causes of peptic ulcer formation.

Acids↗
PubMed2001

The gene for alternative oxidase-2 (AOX2) from Arabidopsis thaliana consists of five exons unlike other AOX genes and is transcribed at an early stage during germination.

We investigated the expressions of genes for alternative oxidase (AOX1a, AOX1b, AOX1c and AOX2) and genes for cytochrome c oxidase (COX5b and COX6b) during germination of Arabidopsis thaliana, and examined oxygen uptakes of the alternative respiration and the cytochrome respiration in imbibed Arabidopsis seeds. A Northern blot analysis showed that AOX2 mRNA has already accumulated in dry seeds and subsequently decreased, whereas accumulation ofAOX1a mRNA was less abundant from 0 hours to 48 hours after imbibition and then increased. The increase of the capacity of the alternative pathway appeared to be dependent on the expressions of both AOX2 and AOX1a. On the other hand, steady-state mRNA levels of COX5b and COX6b were gradually increased during germination, and the capacity of the cytochrome pathway was correlated with the increase of expressions of the COX genes. Antimycin A, the respiratory inhibitor, strongly increased the expression of AOX1a but had no effect on the expression of AOX2. A 5'RACE analysis showed that AOX2 consists of five exons, which is different from the case of most AOX genes identified so far. Analysis of subcellular localization of AOX2 using green fluorescent protein indicated that the AOX2 protein is imported into the mitochondria.

Amino Acid Sequence↗
PubMed2000

Leukemia inhibitory factor gene improves skin allograft survival in the mouse model.

BACKGROUND: Leukemia inhibitory factor (LIF) is a widely expressed cytokine involved in both local and systemic immune response. Furthermore, it has been implicated in various immunological processes including thymic T cell maturation and embryo implantation. We investigated implication of various modalities in the application of prolonged and viable allograft to the wound, using cytokines and growth factors. MATERIALS: BALB/c and B6D2F1 strains of mice were used either as a skin graft donor or host. LIF cDNA inserted in plasmid vector or the vector alone was injected intradermally in graft skin and observed up to 21 days. LIF, LIF-receptor, gp130, as well as type 1 and 2 T helper cytokine expressions were investigated by reverse transcription polymerasse chain reaction, in situ hybridization, and histological studies. RESULTS: LIF cDNA-treated groups showed significantly improved graft survival compared to the vector-treated control in 21 days postoperatively for grafting from B6D2F1 to BALB/c and BALB/c to B6D2F1. LIF and LIF receptor mRNA expressions were observed 24 hr and 21 days posttransplantation. The gp130 expression was only observed in LIF-treated B6D2F1 to BALB/c allografting on day 21 posttransplantation. LIF transcripts were strongly present in the epidermal, dermal, and subdermal tissues as determined by an in situ hybridization of LIF-treated grafting. CONCLUSIONS: These results suggest that LIF cDNA treatment is an effective and beneficial adjuvant for the skin allograft survival. Improved skin allograft modulation by cytokine gene transfer is a potentially promising therapy for temporary large skin coverage.

Animals↗
PubMed2000

Expression of alpha-expansin genes in young seedlings of rice (Oryza sativa L.).

Rice is the only cereal in which germination and coleoptile elongation occur in hypoxia or anoxia. Little is known of the molecular basis directly underlying coleoptile cell extension. In this paper, we describe the expression of alpha-expansin genes in embryos during seed development and young seedlings grown under various oxygen concentrations. The genes Os-EXP2 and Os-EXP1 were predominantly expressed in the developing seeds, mainly in newly developed leaves, coleoptiles, and seminal roots. These expansins expressed in the developing seeds may give cells the potential to expand after seed imbibition begins. In coleoptiles, Os-EXP4 and Os-EXP2 mRNAs were greatly induced by submergence, while they were weakly detected in aerobic or anoxic conditions. Under submerged soil conditions, the signals hybridized with probes Os-EXP4 and Os-EXP2 in coleoptiles were strongest when coleoptiles elongated in the water layer. These data show that expansin gene expression is highly correlated with coleoptile elongation in response to oxygen concentrations. The Os-EXP4 gene was also expressed in leaves, mesocotyls, and coleorhizas of young seedlings. The growth of these tissues was also correlated with the presence of expansins. Therefore, the evidence derived from this study clearly demonstrates that expansins are indispensable for the growing tissues of rice seedlings.

Gene Expression Regulation, Developmental↗
PubMed2000

Ectopic expression of c-myc fails to overcome downregulation of telomerase activity induced by herbimycin A, but ectopic hTERT expression overcomes it.

Telomerase plays a key role in the maintenance of chromosomal stability in tumors, but the mechanism regulating telomerase activity is still unclear. Recent studies have suggested that c-myc may be vital for regulation of hTERT mRNA expression and telomerase activity. In this study, we investigated the changes of telomerase activity and telomerase-related genes induced by herbimycin A in K562 human chronic myelogeous leukemic cells. Telomerase activity showed a biphasic pattern in herbimycin A-treated K562 cells. Initially, the telomerase activity decreased along with the decline of cells in S and G2/M phases, but it recovered slightly at the end of treatment. Expression of mRNA for the telomerase catalytic subunit (hTERT) was decreased before the decline of telomerase activity, and increased slightly before the reactivation of telomerase activity. During herbimycin A treatment, both c-myc and cyclin D1 mRNA showed transient downregulation before the increase of G1 cells. Herbimycin A treatment caused the downregulation of both telomerase activity and hTERT mRNA in cyclin D1-transfected K562 cells, while telomerase activity was partially restored in c-Myc-transfected cells. In contrast, hTERT-transfected K562 cells maintained a high level of telomerase activity during herbimycin A treatment. Neither the template RNA component of telomerase (hTERC) nor telomerase-associated protein (TEP-1) were altered in any of the transfected K562 cells. These results indicate that telomerase activity is mainly regulated by hTERT, and that c-Myc protein is one of the positive regulators of hTERT in leukemic cells but is not enough to counteract the downregulation of telomerase activity by herbimycin A completely.

Benzoquinones↗
PubMed2000

Atomic force microscopy with carbon nanotube probe resolves the subunit organization of protein complexes.

Among many scanning probe microscopies, atomic force microscopy (AFM) is a useful technique to analyse the structure of biological materials because of its applicability to non-conductors in physiological conditions with high resolution. However, the resolution has been limited to an inherent property of the technique; tip effect associated with a large radius of the scanning probe. To overcome this problem, we developed a carbon nanotube probe by attaching a carbon nanotube to a conventional scanning probe under a well-controlled process. Because of the constant and small radius of the tip (2.5-10 nm) and the high aspect ratio (1:100) of the carbon nanotube, the lateral resolution has been much improved judging from the apparent widths of DNA and nucleosomes. The carbon nanotube probes also possessed a higher durability than the conventional probes. We further evaluated the quality of carbon nanotube probes by three parameters to find out the best condition for AFM imaging: the angle to the tip axis; the length; and the tight fixation to the conventional tip. These carbon nanotube probes, with high vertical resolution, enabled us to clearly visualize the subunit organization of multi-subunit proteins and to propose structural models for proliferating cell nuclear antigen and replication factor C. This success in the application of carbon nanotube probes provides the current AFM technology with an additional power for the analyses of the detailed structure of biological materials and the relationship between the structure and function of proteins.

Carbon↗
PubMed2000

The cell biological application of carbon nanotube probes for atomic force microscopy: comparative studies of malaria-infected erythrocytes.

We describe the first cell biological application of carbon nanotube (CN) probes for atomic force microscopy studies. Topographic and phase images were collected from Plasmodium falciparum malaria-infected erythrocytes using both TappingMode Etched Silicon Probes (TESP probe) and CN probes. We estimate that the lateral resolution of a CN probe-generated topographic image is at least four-fold higher than that of the TESP probe. Carbon nanotube probe-generated phase images of P. falciparum-induced knobs on the surface of erythrocytes also show a markedly higher lateral resolution than comparable TESP probe-generate phase images of the same area. We conclude that CN probes are useful for cell biological atomic force microscopy studies and should play an increasingly important role in the future of this evolving discipline.

Animals↗
PubMed2000

Leukemia inhibitory factor enhances bone formation in calvarial bone defect.

For bone defect reconstruction, locally administered cytokine plasmid was examined. Leukemia inhibitory factor (LIF) can bind to the osteoblast cell surface and induce bone formation both in vitro and in vivo. The authors investigated the local mouse LIF complementary deoxyribonucleic acid (cDNA) plasmid in the pcDNA 3 expression vector, which is promoted by cytomegalovirus and is stabilized by bovine growth hormone polyadenylation, with a gelatin sponge carrier. A total of 150 male Wistar rats were used. They were divided into three groups. Group 1 (N = 30) was treated with the gelatin carrier of the pcDNA 3 vector, group 2 (N = 90) was treated with three different doses of LIF cDNA (0.1, 1, and 10 micrograms) in the pcDNA 3-vector plasmid along with the gelatin carrier, and group 3 (N = 30) was treated with recombinant human bone morphogenetic protein -2. Ten animals in each group were euthanized at 1, 3, and 5 weeks postoperatively. Animals treated with LIF cDNA showed significantly enhanced bone mineral density (p < 0.05), as confirmed by dual-energy X-ray absorptiometry (DEXA), in 3 weeks compared with the control vehicle. By 3 weeks, the number of fibroblast-like cells and collagen fibers decreased, whereas the osteoblast-like cells increased inversely, as revealed during histological examination. LIF messenger ribonucleic acid demonstrated by in situ hybridization was observed most markedly in osteocytes of the LIF cDNA-treated group. Also, LIF peptide was detected in the same cell type by immunohistochemistry. Locally administered LIF cDNA plasmid in a gelatin carrier can increase bone density significantly, with subsequent bone formation, probably via osteocyte activation.

Analysis of Variance↗