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Biomedical subjects

A Satake

Publications and source records attributed to A Satake.

At least 19 recordsLinked to original sources
PubMed2002

Long-term outcome after allogeneic bone marrow transplantation for hematological malignancies with non-remission status. Results of a single-center study of 24 patients.

To investigate the problem of allogeneic bone marrow transplantation (allo-BMT) for advanced stage patients, we retrospectively analyzed 24 consecutive patients who underwent allo-BMT in the non-remission stage. Twenty-four patients (19 males and 5 females) with acute leukemia, chronic myelogenous leukemia, and malignant lymphoma underwent allo-BMT. The patients had a median age of 30 years. There were eight cases of acute myelogenous leukemia (AML), six cases acute lymphocytic leukemia (ALL), nine cases of chronic myelogenous leukemia (CML), and one case of Burkitt's lymphoma. The 3-year overall survival rate was 22.5%, with a median survival time of 206 days in AML, 345 days in ALL, and 363 days in CML. Overall survival was associated with a recovery of platelets of less than 30 days and an acute graft-versus-host disease (acute GVHD) presence of less than grade II ( p=0.042). Fourteen patients died of transplantation-related diseases. Our important problem is to decrease transplantation-related deaths in allo-BMT during the non-remission stage, and longer survival can be expected with better pretreatment and prophylaxis for GVHD. In addition, the selection of the source of hematopoietic stem cell transplantation at an optimal time is considered to be another problem to be approached.

Adolescent↗
PubMed2001

Synthesis of bipyridylene-bridged bisporphyrin by nickel-mediated coupling reaction: ON-OFF control of cofacial porphyrin unit by reversible complexation.

Novel bipyridylene-bridged bisporphyrin 1a, in which two porphyrin units were attached directly to symmetrical 4,4'-positions of the 2,2'-bipyridyl group, was synthesized by a nickel(0)-mediated homocoupling reaction of 5,10,15-tris(n-heptyl)-20-(2'-bromo-4'-pyridyl)porphyrinatozinc (3a) in 58% yield. Spatial geometries of two porphyrins in 1a were regulated by reversible complexation of the bipyridyl part with PdCl(2). Thus, the addition of 2.2 equiv of palladium chloride to 1a converted the freely rotating conformation to the cofacial bisporphyrin 2a. The subsequent addition of 4,4'-dimethyl-2,2'-bipyridine 9 regenerated the initial bisporphyrin 1a.

Journal Article↗
PubMed2001

Artificial ion channels showing rectified current behavior.

Voltage-dependent artificial ion channels 3 and 4 were synthesized. Two cholic acid derivatives were connected through a m-xylylene dicarbamate unit at 3-hydroxyl groups. Asymmetries were introduced by terminal hydrophilic groups, carboxylic acid and phosphoric acid for 3 and hydroxyl and carboxylic acid for 4. Under basic conditions, these headgroups in 3 and 4 are expected to be dissociate into -1/-2 (pH 8.2) and 0/-1 (pH 7.2), respectively. Single ion channel properties were examined by a planar bilayer lipid membrane method under symmetrical 500 mM KCl at pH 8.2 or 7.2. When 3 and 4 were introduced into the bilayer membrane under application of positive voltage (a positive-shift method), the current values at positive applied voltage were larger than the corresponding ones at the negative applied voltage. The current-voltage plots were fitted by curves through a zero point to show clear rectification properties. The direction of rectification could be controlled by positive- or negative-shift methods. Vectorial alignment of terminal headgroup charges by the voltage-shift incorporation is essential for giving voltage-dependent rectified ion channels.

Carbamates↗
PubMed2001

Variable timing of reproduction in unpredictable environments: adaption of flood plain plants.

We study the evolutionarily stable reproductive timing of annual plants that face unpredictable environmental disturbances. Plants living in a riverbed often experience a disturbance before they reproduce, suffering major fitness loss. Plants reproducing prior to the flood season are free from the risk of lost reproduction, but a small flowering plant can produce only a few numbers of seeds. If the date of disturbance is unpredictable, a mixed strategy of reproductive timing may evolve in which individuals of the same genotype have different reproductive dates. We calculate the evolutionarily stable phenotype distribution analytically. Depending on parameters, the ESS distribution is either (1) a timid strategy-the plant reproduces when small, prior to the major disturbance season; (2) a bold strategy-the plant reproduces only when it is fully grown; (3) a mixture of early and late reproduction; or (4) dates of reproduction spread over a wide interval. We also examine the effects of developmental and environmental noises that make realized flowering dates deviate from that programmed by the genotype, which follows the ESS distribution. In the presence of noise, the ESS distribution of programmed timing of reproduction is discrete.

Climate↗
PubMed2001

Evaluation of insulin secretion of isolated rat islets cultured in extracellular matrix.

Islet isolation involves enzymatic digestion of the interstitial matrix and mechanical disruption of the tissue. It is possible that a fundamental change of islet biology resulting from the loss of critical factors required for islet function or survival will occur. Extracellular matrix (ECM) is one of the most important components of the islet microenvironment. Reconstruction of the cell-matrix relationship seems to be effective for improving the loss of differentiated islet structure and function. The purpose of this study was to characterize and compare the effects of collagen gel mixture or Matrigel on beta-cell function and islet cell survival. After isolation by the collagenase digestion technique, rat islets were divided and cultured with various types of collagen gel mixture. They were assessed for their glucose-stimulated insulin secretion and cell viability. Glucose-induced insulin secretion of islets cultured with collagen type I gel or a mixture of collagen type I and IV was improved after 11 days in culture. In conclusion, a type of gel composed of collagen type I and/or type IV as an islet microenvironment is sufficient to maintain glucose responsiveness and may be useful for islet transplantation.

Animals↗
PubMed2001

Development of a new method to induce angiogenesis at subcutaneous site of streptozotocin-induced diabetic rats for islet transplantation.

The subcutaneous space is a potential site for clinical islet transplantation. Even though there are several advantages, poor blood supply at this site mainly causes failure of islet survival. In this study, angiogenesis was induced in advance at the diabetic rats subcutis for islet transplantation by implanting a polyethylene terephthalate (PET) mesh bag containing gelatin microspheres incorporating basic fibroblast growth factor (bFGF) (MS/bFGF) and a collagen sponge. The bFGF was incorporated into gelatin microspheres for controlled release of bFGF. As controls, a PET mesh bag with or without either collagen sponges or MS/bFGF was implanted at the subcutaneous site of diabetic rats. Macroscopic and microscopic examinations revealed the formation of capillary network in and around the PET mesh bag containing MS/bFGF and collagen sponges 7 days after implantation when compare with other control groups. When tissue hemoglobin level was also measured, a significantly high level of hemoglobin amount was observed compared with that of control groups. When allogeneic islets mixed with 5% agarose were transplanted into the prevascularized rat subcutis, normoglycemia was maintained for more than 40 days, while other control groups were ineffective. This study demonstrated that combination of gelatin microspheres incorporating bFGF and collagen sponges enabled the mesh to induce neovascularization even at the subcutaneous site of streptozotocin-induced diabetic rats, resulting in improved function of islet transplantation.

Animals↗
PubMed2001

Isolation, culture, and characterization of endocrine cells from 6-month-old porcine pancreas.

Porcine endocrine cells were isolated from pancreas of 6-month-old pigs by two-step enzymatic digestion procedures. They were separated by the density gradient (isopycnic) centrifugation method using Histopaque-1077. Isolated cells were cultured and divided into two groups: suspension cells and adhesion cells. Suspension cells maintained their cell numbers on and after 7 days in culture. Approximately 1 x 10(7) cells were obtained from single pancreas of a 6-month-old pig. The cultured suspension cells took up dithizone (DTZ) staining 14 days after isolation in culture and indicated the presence of beta-cells. In in vitro study, the suspension cells were capable of secreting insulin into the culture medium. The suspension cells were tested for insulin and glucagon staining by Western blot analysis. These results indicated the maintenance of endocrine cell function after isolation. However, cultured adhesion cells failed to maintain their function during culture. In in vivo study, the suspension cells were transplanted into diabetes-induced nude mice. Reduction in blood glucose level was obtained after transplantation. Intraperitoneal glucose tolerance test (IPGTT) results showed a normal pattern of blood glucose clearance. After 1 week, the transplanted endocrine cells were detected with anti-insulin antibody by immunostaining and it showed the presence of viable beta-cells under the renal capsule of nude mice. Collectively, our results suggest that isolated and cultured suspension porcine endocrine cells maintained their endocrine function. These endocrine cells can be used as isolated islets for further study, including transplantation experiments.

Animals↗
PubMed2000

Pollen coupling of forest trees: forming synchronized and periodic reproduction out of chaos.

Many of the tree species in mature forests show masting; their reproductive activity has a large variance between years and is often synchronized between different individuals. In this paper, we analyse a globally coupled map model in which trees accumulate photosynthate every year, produce flowers when the energy reserve level exceeds a threshold, and set seeds and fruits at a rate limited by pollen availability. Without pollen limitation, the trees in the forest show independent chaotic fluctuation. Coupling of trees via pollen exchange results in reproduction being synchronized partially or completely over the forest. The whole forest shows diverse dynamical behaviors determined by the values of two essential parameters; the depletion coefficient k and the coupling strength beta. We find perfectly synchronized periodic reproduction, synchronized reproduction with a chaotic time series, clustering phenomena, and chaotic reproduction of trees without synchronization over individuals. There are many parameter windows in which synchronized reproduction of trees shows a stable periodic fluctuation. For perfectly synchronized forests, we can calculate all the Lyapunov exponents analytically. They show that synchronized reproduction of all the trees in the forest can only occur when trees flower at low (but positive) levels in a significant fraction of years, resulting in small fruit sets due to outcrossed pollen limitation. This is consistent with the observation that the distinction between mast years and non-mast years is often not clear cut.

Models, Biological↗
PubMed1999

Expression of protective protein in human tissue.

The authors investigated by immunohistochemistry the distribution of protective protein in human tissues. Immunoreactivity was observed in the cytoplasm, revealing a granular pattern and cell type specificity. The most intense staining was observed in the large neurons of brain, distal and collecting tubular cells of kidney, epithelial cells of bronchus, and Leydig cells of testis. In a patient with galactosialidosis type IIa, all these stains were absent. The neurons that were most strongly stained in the control group, such as the Betz cells, neurons in the basal forebrain, motor neurons in the cranial nerve nuclei, and ventral horn cells of the spinal cord, were markedly ballooned in the patient with galactosialidosis.

Adolescent↗
PubMed1999

Production of monoclonal antibody and development of enzyme-linked immunosorbent assay for kanamycin in biological matrices.

Monoclonal antibodies (MAbs) against kanamycin were prepared by using a kanamycin-bovine gamma-globulin conjugate for the immunization of mice. Splenocytes from BALB/c immunized mice were fused with P3X63Ag8U.1 myeloma cells. This resulted in two hybridoma cell lines. Fifty per cent inhibition concentrations (IC50) for the MAbs were 2 and 5 ng ml-1. One MAb (IC50 = 2 ng ml-1) was named #22 and was used to develop quantitative assays for kanamycin by means of an enzyme-linked immunosorbent assay (ELISA). The detection limit was 0.2 ng ml-1 and the standard deviations were 0.2-4.4% for intra-assay and 0.6-4.7% for inter-assay, respectively. The detection limits using peroxidase were 4 ppb in cattle milk, cattle plasma, cattle urine, swine plasma, swine urine and chicken plasma. Using the MAb #22 produced, a rapid test kit based on an immunochromatographic method was developed. The detection limits using the kit were 50 ppb in cattle milk, cattle plasma, cattle urine and chicken plasma.

Animals↗
PubMed1998

Noise-induced regularity of spatial wave patterns in subalpine abies forests

In subalpine forests dominated by Abies species in Japan and northeastern United States, trees show traveling wave of regeneration with many striped zones of tree dieback, moving downwind at a constant rate. Previous theoretical studies have demonstrated that a very simple model can generate wave-like spatio-temporal patterns of tree regeneration in a lattice-structured habitat with each site occupied by a cohort of trees. A cohort taller than the average height of its windward neighbor experiences stand-level dieback in the next time step and the height becomes zero. Otherwise the cohort increases its height at a constant rate. Starting from a random initial pattern, this simple deterministic model can generate a saw-toothed pattern that moves downwind at a constant rate, but the distance between adjacent dieback zones has a large variance. In this paper, we study the effects of "noises" in tree dieback rules in two forms which help to generate more regular patterns: (1) additional random disturbances at a low rate, which change the size of "clusters" (defined as a group of cohorts between adjacent dieback zones) by splitting a large cluster into two or by merging a small one with a neighbor, and (2) the stochastic rule of tree dieback, represented by the probability of dieback in unit time being a sigmoidal function of the difference in the tree height between the site and the windward neighbors. These noises are effective both for one-dimensional and two-dimensional models, but spatial patterns are much more regular in the two-dimensional model than in the one-dimensional model. Copyright 1998 Academic Press

Journal Article↗
PubMed1998

Monoclonal-based enzyme-linked immunosorbent assay and immunochromatographic rapid assay for monensin.

Monensin, a member of the ionophoric polyether antibiotics, is used primarily as a coccidiostat. A protein conjugate of monensin was prepared and utilized to produce monoclonal antibodies in the BALB/c-P3X63Ag8U.1 fusion system. Only one hybridoma that produces monoclonal antibody against monensin was isolated from one in 329 wells. The monoclonal antibody was used to develop quantitative assays for monensin by means of an enzyme-linked immunosorbent assay (ELISA). The detection limit was 1 ng ml-1 and the relative standard deviations were 2.1-6.3% intra-assay and 5.9-12.9% inter-assay. All ELISA results for assay of chicken plasma and cattle milk were confirmed using a bioassay to be used as the official method. The ELISA and bioassay results showed close correlations for plasma (r2 = 0.98, n = 25) and milk (r2 = 0.95, n = 25). Using the anti-monensin monoclonal antibodies produced, a rapid test kit based on the immunochromatographic method was developed. Detection limits of monensin for cattle milk, cattle plasma and chicken plasma were about 40, 40 and 160 ppb. respectively.

Animals↗
PubMed1995

Protective protein as an endogenous endothelin degradation enzyme in human tissues.

An enzyme hydrolyzing the carboxyl terminus of endothelin-1 was detected in control human tissues but was deficient in tissues from a patient with galactosialidosis, a metabolic disease caused by the protective protein gene mutation. It was proportional to the amount of immunologically estimated mature protective protein. An antibody against the lysosomal protective protein/beta-galactosidase complex precipitated the enzyme activity almost completely. Transfection of the human cDNA for protective protein resulted in high expression of the enzyme activity in transformed fibroblasts from a galactosialidosis patient. These results indicated that the mature protective protein is a major soluble endogenous endothelin degradation enzyme in human tissues.

Brain↗
PubMed1995

Measles encephalomyelitis in a patient with a history of vaccination.

Secondary vaccine failure (SVF) of measles is generally believed to run a milder course of illness than an ordinary course of infection. Severe complications such as central nervous system involvement have rarely been reported. A 12 year old girl, who had received a live attenuated measles vaccine 10 years earlier, developed an encephalomyelitis in the absence of symptoms indicative of ordinary measles such as Koplik spots. Anti-measles hemagglutination inhibition (HI) titer and measles IgM and IgG antibody titers were measured in a commercial laboratory. Measles virus genomic sequence was detected by polymerase chain reaction. Both serum and cerebrospinal fluid (CSF) samples obtained at acute phase already showed extremely high titers of HI (x8192 in serum and x1024 in CSF, respectively) and IgG antibody along with the presence of IgM antibody. Polymerase chain reaction detected the measles virus genomic sequence in the acute phase CSF. The patient's definite history of measles vaccination, high titers of HI and IgG antibodies observed at the very early stage of illness and the clinical course indicated that this patient has an encephalomyelitis due to SVF of measles. It is suggested that measles virus can be a pathogen of encephalitis without symptoms indicative of ordinary measles in individuals who received live attenuated measles vaccines.

Child↗