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K Hama

Publications and source records attributed to K Hama.

At least 37 records · Page 2Linked to original sources
PubMed1998

The effect of exposure to negative air ions on the recovery of physiological responses after moderate endurance exercise.

This study examined the effects of negative air ion exposure on the human cardiovascular and endocrine systems during rest and during the recovery period following moderate endurance exercise. Ten healthy adult men were studied in the presence (8,000-10,000 cm-3) or absence (200-400 cm-3) of negative air ions (25 degrees C, 50% humidity) after 1 h of exercise. The level of exercise was adjusted to represent a 50-60% load compared with the subjects' maximal oxygen uptake, which was determined using a bicycle ergometer in an unmodified environment (22-23 degrees C, 30-35% humidity, 200-400 negative air ions.cm-3). The diastolic blood pressure (DBP) values during the recovery period were significantly lower in the presence of negative ions than in their absence. The plasma levels of serotonin (5-HT) and dopamine (DA) were significantly lower in the presence of negative ions than in their absence. These results demonstrated that exposure to negative air ions produced a slow recovery of DBP and decreases in the levels of 5-HT and DA in the recovery period after moderate endurance exercise. 5-HT is thought to have contributed to the slow recovery of DBP.

Adult↗
PubMed1998

Hyperglycemia is a factor for an increase in serum ceruloplasmin in type 2 diabetes.

OBJECTIVE: To examine if there is a correlation between high blood glucose and serum ceruloplasmin (Cp) levels. RESEARCH DESIGN AND METHODS: Serum Cp levels were measured in 637 patients with type 2 diabetes (all type 2 diabetes group). For the follow-up type 2 diabetes group, 161 patients who had not had any changes in their situation during the last year that are known to influence serum Cp levels were reexamined 1 year later. The control group was composed of 158 healthy individuals. Serum Cp and blood HbA1c levels were measured by radial immunodiffusion and high-performance liquid chromatography assays, respectively. RESULTS: Serum Cp levels in the all type 2 diabetes group were significantly higher than those in the control group (P < 0.0001), although the serum Cp levels did not correlate with the blood HbA1c levels in the all type 2 diabetes group (r = 0.055, P = 0.351). Then we evaluated those factors (delta-log Cp and delta-HbA1c) in the follow-up type 2 diabetes group to minimize changes from the genetic differences and to exclude any known factors influencing serum Cp levels. This indicated that the delta-HbA1c had a positive correlation to the delta-log Cp (r = 0.304, P < 0.0001). CONCLUSIONS: A persistent high blood glucose (namely HbA1c) is associated with an increase in serum Cp levels over 1 year.

Adult↗
PubMed1996

Manual and automated (robotic) high-performance liquid chromatography methods for the determination of mycophenolic acid and its glucuronide conjugate in human plasma.

A manual and an automated (Zymark PyTechnology robot) HPLC method for simultaneous determination of plasma mycophenolic acid (MPA) and its glucuronide conjugate (MPAG) are described here. Both methods are reproducible and accurate, and both are equivalent in all respects, including quantification limits (MPA, 0.100 microgram/ml; MPAG, 4.00 micrograms/ml), range (using 0.05-0.5 ml of plasma: MPA, 0.0500-20.0 micrograms/aliquot; MPAG, 2.00-200 micrograms/aliquot), precision, and accuracy. MPA and MPAG were stable under the conditions used with both methods. Results from aliquots of paired control samples, analyzed by the manual method over three years at six analytical laboratories, showed excellent agreement in precision and accuracy.

Chromatography, High Pressure Liquid↗
PubMed1996

Changes of intermediate filaments in cultured human glioma cells with various growth factors and cytokines using high voltage immunoelectron microscopy.

Morphological and immunocytological changes of intermediate filaments of cultured human malignant glioma cells were studied by adding various growth factors or cytokines using stereoscopic high voltage electron microscopy operated at 1,000 kV. The gold-colloid immuno-cytochemical method was used to stain GFAP and vimentin. Growth rate of tumor cells increased when EGF, TGF-alpha, and PDGF administered and decreased when FGF, TNF, and CLN-IgG administered. Morphological changes of cells were not remarkable when EGF, PDGF, IL-1, and FGF were administered. The cytoplalsmic organellaes were damaged after administrating TNF and CLN-IgG to cells.

Brain Neoplasms↗
PubMed1994

Three-dimensional organization of neuronal and glial processes: high voltage electron microscopy.

Neurons and glia cells in the mammalian central nervous system have many complicated processes. They are too fine for light microscopic study and too complicated and widely spread for thin section electron microscopy. High-voltage electron microscopic (HVEM) stereo observation of thick Golgi preparation provides detailed 3-D images of their processes. Three-dimensional fine structures of astocytic processes in the neuropile and on the surface of neuronal somata, and those of the ruffed cell axon initial segment and thorny excrescences of CA3 pyramidal cell dendrites, are elucidated with the aid of HVEM stereoscopy of thick Golgi preparations. In addition, some results obtained by 3-D morphometrical analysis of dendritic spines using HVEM stereo images are shown. The examples presented here clearly show the usefulness of high-voltage electron microscope stereo observation of thick specimens for detailed morphological and morphometric study of the central nervous system.

Animals↗
PubMed1994

Serial section electron tomography: a method for three-dimensional reconstruction of large structures.

We present a method for combining single axis tomography and serial sectioning techniques to derive a three-dimensional reconstruction of large structures at electron microscopic resolution. This serial-tomography method allows the use of sufficiently thin sections to achieve adequate resolution with electron tomography, yet enables the generation of large reconstructions with considerably fewer sections than would be required using a serial thin section reconstruction technique. Serial thick sections (1-2 microns) are cut through the structure of interest, tomographic volume reconstructions are obtained for each section from a single axis tilt series, and the resulting series of volumes are then aligned and combined to form a single large volume. The serial-tomography method is illustrated with several samples, including red blood cells, the Golgi apparatus, and a spiny dendrite of a cortical pyramidal neuron. In some of these samples, the reconstruction is compared to correlated light microscopic views. The resulting large volume reconstructions appear to represent accurately the size and shape of objects such as red blood cells and spiny dendrites. The continuity of complex, tortuous structures such as the Golgi apparatus is also maintained across serial volumes. These examples demonstrate that it is possible to align and link a series of tomographic volumes accurately and that serial-tomography is a useful method for reconstructing relatively large structures without resorting to large numbers of serial thin sections.

Animals↗
PubMed1992

Neurotrophic action of gliostatin on cortical neurons. Identity of gliostatin and platelet-derived endothelial cell growth factor.

Gliostatin is a polypeptide growth inhibitor of apparent M(r) = 100,000 with a homodimeric structure comprising two 50-kDa subunits, acting on astrocyte as well as astrocytoma cells (Asai, K., Hirano, T., Kaneko, S., Moriyama, A., Nakanishi, K., Isobe, I., Eksioglu, Y.Z., and Kato, T. (1992) J. Neurochem., 59, 307-317). The amino acid sequences of 13 tryptic peptides including the amino terminus were completely identical to those of platelet-derived endothelial cell growth factor (PD-ECGF) (Ishikawa, F., Miyazono, K., Hellman, U., Drexler, H., Wernstedt, C., Hagiwara, K., Usuki, K., Takaku, F., Risau, W., and Heldin, C.-H. (1989) Nature 338, 557-562). Gliostatin and PD-ECGF, purified from human placenta, shared growth inhibition on glial cells and growth promotion on endothelial cells, and exhibited similar values for half-maximal dose of glial growth inhibition (ID50 = 1.3 nM) and the half-maximal concentration of endothelial growth promotion (EC50 = 1.0 nM), suggesting that both factors evoke the biological actions through an identical receptor on each cell surface. We have further demonstrated evidence of a novel neurotrophic action of gliostatin/PD-ECGF toward embryonic rat cortical neurons in culture. The half-maximal concentration of gliostatin/PD-ECGF for neurotrophic action was 0.3 nM. All actions on glial, endothelial, and neuronal cells, were abolished by a monoclonal antibody against gliostatin. These data indicate that gliostatin/PD-ECGF may play important roles on development and regeneration of the central nervous system and may also involve the induction of angiogenesis for the formation of blood brain barrier.

Amino Acid Sequence↗
PubMed1992

Production of IL-4, IL-2, IFN-gamma, and TNF-alpha by peripheral blood mononuclear cells of patients with atopic dermatitis.

Recently, T cell-derived cytokines have been postulated to be involved in the pathogenesis of atopic dermatitis (AD) since the synthesis of IgE is profoundly regulated by cytokines such as IL-4, IFN-gamma and IL-2. IL-4 enhances the production of IgE and in contrast, IFN-gamma inhibits this IL-4-mediated IgE production. IL-2 also prevents IL-4-induced production of IgE by a different mechanism from IFN-gamma, suggesting that the level of IgE is regulated by the quantitative balance of these antagonizing cytokines. We examined the production of IL-4, IL-2, IFN-gamma and TNF-alpha by PBMC of AD patients and non-AD controls. Although the production of IL-2 and TNF-alpha by AD patients was significantly lower than that of non-AD controls, the production of IL-4 and IFN-gamma did not show significant differences between AD and non-AD individuals. There was no significant correlation between cytokine production and clinical symptoms in AD patients. There was significant positive correlation between IL-4 and IL-2 production, and between IFN-gamma and TNF-alpha production. Serum IL-4 levels showed no significant difference between AD group and non-AD group.

Adolescent↗
PubMed1991

An approach to imaging of living cell surface topography by scanning tunneling microscopy.

Since a scanning tunneling microscope (STM) was developed, an observation of living cell surface has been one of the final aims in the biological application of STM. By developing a new style of STM which was combined with an optical microscope and with a novel system for the centering of both images, we successfully got the STM images of living cell surface of T24 cells (human bladder cancer cell line) and CHO cells (Chinese hamster ovary fibroblast) cultured on highly oriented pyrolytic graphite under the appropriate condition (V greater than 8.0 V, I less than 0.2 nA). Unexpectedly, the living T24 cell showed a slightly uneven surface with a steep foot slope. The CHO cell showed more rough surface with steeper slope of cell foot. Although the STM system had a fine spatial resolution less than 3 nm, the profile of living cell surface covered with electrolyte was clear only when the scanning area was more than 10 microns square.

Animals↗
PubMed1991

Different stromal cell lines support lineage-selective differentiation of the multipotential bone marrow stem cell clone LyD9.

An interleukin 3-dependent multipotential stem cell clone, LyD9, has been shown to generate mature B lymphocytes, macrophages, and neutrophils by coculture with primary bone marrow stromal cells. We report here that coculture with the cloned stromal cell lines PA6 and ST2 can support differentiation of LyD9 cells predominantly into granulocyte/macrophage colony-stimulating factor (GM-CSF)- and granulocyte (G)-CSF-responsive cells, respectively. However, these stromal cell lines were unable to support lymphopoiesis of LyD9 cells. The GM-CSF-dependent line, L-GM, which was derived from LyD9 cells cocultured with PA6 stromal cells, could differentiate into macrophages and granulocytes in the presence of GM-CSF. The L-GM line can further differentiate predominantly into neutrophils by coculture with ST2 stromal cells. The G-CSF-dependent line, L-G, which was derived from LyD9 cells cocultured with ST2 stromal cells, differentiated into neutrophils in response to G-CSF. Although the stromal cell-supported differentiation of LyD9 cells required the direct contact between LyD9 and stromal cells, a small fraction of LyD9 cells that were pretreated with 5-azacytidine could differentiate into neutrophils and macrophages without direct contact with stromal cells. These results indicate that different stromal cell lines support lineage-selective differentiation of the LyD9 stem cell and that 5-azacytidine treatment can bypass the requirement of direct contact with stromal cells, albeit with a lower frequency.

Animals↗
PubMed1991

The transverse tubular system of the hypertrophic myocardium: morphology and morphometry in spontaneous hypertensive rats (SHR).

We reported previously on a modified Golgi stain that, in conjunction with high voltage electron microscope stereoscopy, gives striking views of the elaborate network of the transverse tubular system (T system) in rat myocardium. In this report we used the same techniques to study three-dimensional arrangements of the T system in the left ventricular myocardium of spontaneous hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY). High voltage electron microscope stereoscopy revealed distinctive morphological characteristics of the T system, such as undulating running, short dead-end branches, and labyrinth-like tubular aggregates in the hypertrophic myocardium of SHR. Quantitative analysis of the SHR T system indicated a surface area greater than that of WKY. These findings may support the hypothesis that making an additional T system membrane will compensate for the smaller surface-to-volume ratio. However, the normal regulatory mechanism required to maintain the surface-to-volume ratio does not function properly in SHR, resulting in morphological abnormalities and functional disturbances of the myocardium.

Animals↗
PubMed1991

Chemical and enzymatic degradation of ganciclovir prodrugs: enhanced stability of the diadamantoate prodrug under acid conditions.

We report the chemical and enzymatic hydrolysis of two hydrophobic prodrugs of ganciclovir (3 = dipropionate ester; 4 = diadamantoate ester). Both prodrugs undergo hydrolysis showing a pH dependence of kobs = kH+aH+ + ko + kHO-aHO- and a pH of maximum stability near pH 5. Only 4 exhibited a shelf life (t90) greater than 2 years. Compound 4 reacts significantly slower than ganciclovir in acidic media, even though the adamantyl esters provide additional reaction sites (which would be expected to increase the rate of degradation) that are distally removed from the guanine ring system, offering negligible steric or electronic substituent effects. Both 3 and 4 hydrolyzed in tissue homogenate, where kobs followed liver greater than intestine much greater than skin. Based on these findings of chemical stability, lipophilicity, and acceptable rate of enzymatic cleavage by skin esterases, 4 meets several of the criteria required for the topical sustained delivery of ganciclovir.

Animals↗
PubMed1990

Intramembrane particles and responses of sensory axon terminals during reinnervation of the frog muscle spindle.

Changes in the density of intramembrane particles (IMPs) of sensory nerve terminals in the bullfrog muscle spindle were correlated with recovery in the response of the spindle to stretch during postcrush reinnervation. A few IMPs on the protoplasmic (P) face in summer experiments (June to October) reappeared by the 3rd week after the nerve crush, then rapidly increased to 110% and 120% of control values 2 and 2.5 months after the crush. Afferent responses to stretch could be recorded after the mean IMP density on the P-face in terminal branches had recovered to more than 25% of the control value. The discharge rate showed a plateau pattern during the period of the excessive IMPs. This was supplanted by a normal pattern after a myelinated branch of the sensory axon was cut. The IMPs in winter experiments (November to April) reappeared by day 90 after nerve crush, and then slowly increased. The sustained responses to stretch reappeared after 5 months, when the mean IMP density on the P-face was restored to 25% or more of the control. Neither excessive density of the IMPs nor plateau pattern of the discharge rate were observed in winter experiments. The relation between the regenerated IMP densities and the functional recovery is discussed.

Action Potentials↗
PubMed1989

Multiple effects of human recombinant interleukin 4 on human myeloid monocyte cell lines.

The effects of recombinant human interleukin 4 (rIL-4) on proliferation and differentiation on human myeloid/monocytic leukemia cell lines were examined. At high concentrations, rIL-4 had a slight enhancing effect on [3H]thymidine incorporation by U937 cells. rIL-4 markedly induced expression of the Fc epsilon receptor (CD23) and the Leu-M3 antigen (CD14) on U937 cells. HL60 and THP-1 cells treated with rIL-4 also showed increased CD23 expression, but little change of CD14 antigen expression. CD23 induction required lower amounts of IL-4 than needed for T cell growth, indicating that CD23 induction on U937 will serve as a sensitive assay for human IL-4. rIL-4 reduced the steady state level of IL-1 beta mRNA in U937.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1989

Three-dimensional morphometrical study of dendritic spines of the granule cell in the rat dentate gyrus with HVEM stereo images.

Number, length, and diameters of dendritic spines of the granule cell in the dorsal leaf of the rat dentate gyrus were measured by using high-voltage electron microscope stereo images of 5-micron-thick Golgi preparations with the aid of a three-dimensional image analyzer system. Spine densities of 2.02 +/- 0.28, 2.28 +/- 0.33, and 3.36 +/- 0.35 per 1 micron at distal, middle, and proximal portions of the dendrite were obtained. These values were about 1.6-fold of the previous light microscopical report. Mean three-dimensional spine length were 1.244 +/- 0.506 micron, 1.262 +/- 0.563 micron, and 1.254 +/- 0.584 micron at distal, middle, and proximal portions, respectively, which were about 1.4 times longer than those measured in two dimensions. By using measured morphometrical parameters of spines such as lengths, diameters, and population densities, total spine surface areas of 2.401 micron 2, 2.806 micron 2, and 4.180 micron 2 per 1 micron of the dendrite at distal, middle, and proximal portions, respectively, were obtained. The total surface area of dendrite was about doubled by the addition of the spines at each dendritic portion. The advantageous features and the problems of the present method are discussed.

Animals↗