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Biomedical subjects

M Taya

Publications and source records attributed to M Taya.

At least 19 recordsLinked to original sources
PubMed2005

Effective phase correction function for high-resolution exit wave reconstruction by a three-dimensional Fourier filtering method.

The phase correction function used in the three-dimensional Fourier filtering method (3D-FFM) for compensating lens aberrations was investigated to reconstruct a high-resolution exit wave of a sample. An appropriate function, which hardly suffered from imperfect illumination conditions, was determined by comparing two types of phase correction functions with numerical calculations and experiments using through-focus images of an amorphous thin film and a [110]-oriented Si single crystal taken under tilted illumination or partially coherent illumination. Theoretical calculations indicated that a function in terms of w (an axial Fourier component), available uniquely in the 3D Fourier space, compensated for the phase shift due to the spherical aberration more precisely than did a conventional function in terms of g (the two-dimensional (2D) planar Fourier components). Experimentally, exit waves reconstructed using the w-function showed sample structures at approximately 20% higher resolution than those reconstructed using the g-function. Image contrast simulations proved that the w-function had a significant advantage over the g-function: the former canceled out the effect of illumination divergence, resulting in a high-resolution exit wave. These results demonstrated that exit waves, which are uniquely realized in the 3D-FFM, should be reconstructed using the w-type phase correction function.

Fourier Analysis↗
PubMed2001

Characterization and application of plant hairy roots endowed with photosynthetic functions.

The scope of this review includes the physiological properties of the hairy roots induced by light irradiation and the kinetic analysis considering the effects of light intensity on hairy root cultures. The cell lines of photomixotrophic and photoautotrophic hairy roots of pak-bung are established from heterotrophic ones by improving the photosynthetic ability of hairy roots through acclimation cultures under light irradiation. Comparisons of physiological properties of derived photoautotrophic cell line with photomixotrophic and heterotrophic ones are also made through histological examination. Moreover, the effect of photosynthesis inhibitor on the photoautotrophic growth of the hairy roots is described. By elucidating the influences of light intensity on growth and chlorophyll formation of photoautotrophic and photomixotrophic hairy roots, a kinetic model was applied to describe the hairy root growth and chlorophyll formation of these cell lines of hairy roots.

Cell Culture Techniques↗
PubMed2001

Reduction in operator supervision time using a modified malfunction detection system with fuzzy inference in an industrial-scale fermentation of alkaline cellulase.

A malfunction detection system based on fuzzy inference, in which a fermentation process is categorized into three states (normal, intermediate and abnormal) according to the computation of malfunction degree, was modified to reduce the supervision tasks required for an industrial-scale production of alkaline cellulase. The time lag of the culture, tau, was determined from the difference in the cumulated amount of CO2 evolved between the actual and standard values. By employing tau, the deviations of the actual values of process data (pH of broth and the amount of antifoaming agent supplied) from the standard values could be compensated for in terms of a delayed or forward effect in fermentation time. In the detection tests conducted for a series of 200 runs using the modified method, two runs and a single run were categorized as belonging to the abnormal and intermediate states, respectively, and all of the other runs were recognized to be in a normal state. As a result, the total supervision time for operators was reduced by the modification.

Journal Article↗
PubMed2001

Evaluation of attachment and growth of anchorage-dependent cells on culture surfaces with type I collagen coating.

The effects of coating the culture surface with bovine type I collagen on the culture properties of anchorage-dependent cells were investigated. When human fibroblasts were cultured on a surface coated with collagen at 5.8 x 10(-3) mg/cm2, cell attachment and subsequent cell growth were both enhanced compared to the culture on an uncoated surface. The degrees of cell attachment and growth enhancement were numerically characterized using the time constant of cell adhesion (tau) and doubling time (t(d)) as kinetic parameters. These parameters applied to cultures of human keratinocytes and rabbit chondrocytes allowed the effects of collagen coating on the respective culture properties of both types of cells to be evaluated. In addition, the relative parameters R(tau) and R(t(d)) (defined as the ratios of the tau and t(d) values at a given collagen concentration against those without collagen coating, respectively) were employed to estimate the effects of collagen based on a standardized criterion. Similar R(tau) and R(t(d)) profiles were obtained for collagen concentrations ranging from 5.8 x 10(-13) to 5.8 x 10(-3) mg/cm2, whether the cells were fibroblasts, keratinocytes or chondrocytes. It was also revealed that coating the surface with collagen at a concentration over 5.8 x 10(-7) mg/cm2 led to reductions in both the R(tau) and R(t(d)) values, i.e. the promotion of cell attachment and growth, in the culture of each type of cells examined.

Journal Article↗
PubMed2000

Culture of red beet hairy roots by considering variation in sensitivity of tip meristems to hydraulic stress.

In the culture of red beet hairy roots in shaking flasks, a period for acclimation without lateral root generation existed at the early stage, and the root tip meristems containing growing points (GPs) were found to be damaged under an elevated shear stress condition. The loading experiments of shear stress to the hairy roots revealed that the GPs subjected to the acclimation acquired tolerance to shear stress, retaining relatively high viability of GPs up to 0.6N/m(2) of loaded shear stress. Next, the hairy roots after culture for 50h at 0.05N/m(2) of shear stress were exposed to conditions at various levels of shear stress in a single column reactor, and a relatively high growth rate was obtained in the vicinity of 1.0N/m(2) of shear stress. According to these results, two-stage cultures of hairy roots were then performed, which was comprised of a first stage for 50h at 0.05N/m(2) of shear stress for the prevention of decay of the GPs caused by hydraulic stress and a second stage for 110h at 1.0N/m(2) of shear stress for active elongation of the GPs with sufficient nutrient supply by regulation of the medium flow rate. The cell concentration ultimately reached 7.6kg dry cells/m(3), although no growth was observed in the case where the hairy roots did not undergo the first stage.

Journal Article↗
PubMed2000

Characterization of energy conversion based on metabolic flux analysis in mixotrophic liverwort cells, Marchantia polymorpha.

In order to characterize the contributions of respiratory and photosynthetic actions to energy conversions, the mixotrophic cells of Marchantia polymorpha were cultivated in the medium containing 10kg/m(3) glucose as an organic carbon source. The cultures were conducted with the supply of ordinary air (0.03% CO(2)) at constant incident light intensities of 50 and 180W/m(2). From the results of metabolic analysis, it was found that the cell yield based on ATP synthesis was estimated to be 6.3x10(-3)kg-dry cells/mol-ATP in these cultures. Under the examined conditions, energy conversion efficiency through respiration was larger than that through photosynthesis, and efficiency of overall energy conversion to ATP was maximized when the sum of energies from glucose and light captured by the cells was approximately 7.2x10(5)J/(hkg-dry cells). Taking into account the efficiency of overall energy conversion, a batch culture of M. polymorpha in a bioreactor was carried out by regulating incident light intensity ranging from 9 to 58W/m(2). In the culture with light regulation, the cell yield of 6.2x10(-9)kg-dry cells/J was achieved on the basis of energy provided to the system throughout the culture, and this value was 2.3 and 9.3 times as large as those obtained in the cultures under constant incident light intensities of 50 and 180W/m(2), respectively.

Journal Article↗
PubMed2000

Viability of plant hairy roots is sustained without propagation in low sugar medium kept at ambient temperature.

The effect of sucrose concentration in the medium on the growth and resumption ability to form lateral roots was investigated using the hairy roots of pak-bung and tobacco. It was found that the growth evaluated by root tip elongation of pak-bung and tobacco hairy roots was suppressed in the medium having an initial sucrose concentration of <2.5kg/m(3), and that the resumption abilities of both the hairy roots could be preserved when the hairy roots were kept at an initial sucrose concentration of 2.5kg/m(3) under ambient temperature conditions. The values of maintenance energy for pak-bung and tobacco hairy roots were determined to be 0.11 and 0.12 per day, respectively, from the total sugar consumption rates. Under the oligotrophic condition of the sucrose concentration of 2.5kg/m(3), the hairy roots were considered to exist as resting cells with maintenance metabolism, and the minimum demand for the energy source to ensure survival of the cells was met because the cells hardly multiplied and sugar consumption was not significant. In addition, long-term storage of pak-bung hairy roots in the liquid medium with 2.5kg/m(3) sucrose was performed at 25 degrees C. It was demonstrated that the hairy roots could maintain their resumption abilities without a serious loss of viability over 600 days and that the number of budding lateral roots per unit length of the main roots remained a value of 72 roots/m after the 600-day storage.

Journal Article↗
PubMed2000

Development and characterization of a photoautotrophic cell line of pak-bung hairy roots.

A cell line of photoautotrophic pak-bung hairy roots was established from photomixotrophic ones by acclimation cultivations with a stepwise change of sucrose concentration in a medium with 3.0% CO2-enriched air supplied under continuous light irradiation. The derived photoautotrophic hairy roots had high chlorophyll content and activity of 1,5-ribulose-bisphosphate carboxylase/oxygenase, the values of which were 4.1- and 2.0-fold more than those of the parent photomixotroph, respectively. Electron microscopic observation revealed that the photoautotrophic hairy root cells possessed well-developed chloroplasts. The activities of ascorbate peroxidase and guaiacoal peroxidase found in the hairy roots were comparable to those found in the leaves and roots of parent plants of pak-bung, respectively. The elongation rate of growing points of the hairy roots was maximum at 5.0% CO2 concentration in gas phase and an incident light intensity of 10 W/m2 under the photoautotrophic conditions examined. Although light was indispensable for ensuring photoautotrophy of the hairy roots, it was found that exposure of the roots to strong light resulted in the reduction in the number of viable growing points governing the overall growth rate of the hairy roots.

Journal Article↗
PubMed2000

Valuation of growth parameters in monolayer keratinocyte cultures based on a two-dimensional cell placement model.

The influence of inoculum size on the growth of keratinocyte cells was investigated in a monolayer culture with serum-free medium. A growth model of cell placement was applied to the expression of the cell adhesion phase after the inoculation, lag phase, exponential growth phase, and stationary phase because of contact inhibition at high cell densities. Based on the model, the lag time until the onset of cell division was shortened in proportion to the logarithm of the inoculum cell size, resulting in the enhancement of overall cell propagation. It was verified that the proposed model is valid for the determination of the optimal inoculum size to realize the efficient growth of keratinocytes, indicating that the model is a useful tool to predict an optimal culture scheme for the production of skin grafts.

Journal Article↗
PubMed2000

Reduction in carbon dioxide emission, and enhancement of cell yield by control of light intensity in photomixotrophic batch culture of Marchantia polymorpha.

Photomixotrophic cultures of Marchantia polymorpha were examined under light irradiation using glucose as an organic carbon source. The activity of ribulose 1,5-bisphosphate carboxylase/oxygenase in the cells was found to be maximum at an absorbed light energy of E(c) = 8.7 x 10(2)W/kg and the respiration rate of the cells remained at a low level in the range of E(c) = 1.7 x 10(2) to 1.5 x 10(3) W/kg. Batch culture of M. polymorpha was carried out in a bioreactor while keeping the E(c) value at about 3.5 x 10(2) W/kg by regulating incident light intensity between 19 and 220 W/m2. During the culture conducted under controlled light, CO2 evolution from the reactor was effectively suppressed and the obtained cell yield was 0.88 kg dry cells/kg glucose, whereas the yield was 0.62 kg dry cells/kg glucose throughout the culture conducted at the constant incident light intensity of 50 W/m2.

Journal Article↗
PubMed1999

Segmentation of plant hairy roots promotes lateral root emergence and subsequent growth.

The influence of root cutting on the emergence of lateral roots was investigated in the cultures of horseradish and madder hairy roots. The original hairy roots prepared for inoculation were cut at various distances from the tips and the resultant segments were cultivated in flasks. It was found that lateral roots very frequently emerged from the segments, depending on the longitudinal positions at which the segments were obtained. To attain the effective growth, cultivation of madder hairy roots with root cutting performed twice at 0 and 360 h was conducted. The emergence of lateral roots facilitated the growth of hairy roots owing to an increase in the number of growing points (GPs). The dry cell mass concentration and the number of GPs were 9.6 kg/m3 and 1.9 x 10(7)/m3 at 672 h of culture time, which were 3.6 and 4.9 times higher, respectively, than those in the control culture without the operation.

Journal Article↗
PubMed1999

Photoautotrophic cultures of the host and transformed cells of Marchantia polymorpha under controlled incident light intensity.

Photoautotrophic cultures of the host and transformed cells of the liverwort, Marchantia polymorpha, were examined. In cultures in flat glass flasks under various light intensities, it was found that the growth rates of both the cells increased with increase in light intensity in the range of 0 to 25 W/m2, but further increase in light intensity caused photoinhibition of the growth of the cells. Cultures of both the types of cells under light-controlled conditions using an externally illuminated bioreactor were carried out taking into consideration the inhibition of cell growth by excessive light and the light intensity distributions in the cell suspensions. In these cultures, 2.1 (transformed cells) and 3.3 (host cells) kg dry cell weight per m3 were harvested at culture times of 9.0 and 10 d, respectively. These values were larger than those obtained in cultures of the respective cells at a fixed incident light intensity of 25 W/m2.

Journal Article↗
PubMed1997

Continuous ambulatory radionuclide monitoring of left ventricular function: effect of body position during ergometer exercise.

UNLABELLED: We assessed the reliability of a continuous ambulatory radionuclide monitoring system (the VEST system, Capintec, Inc., Ramsey, NJ) for measurement of left ventricular performance during exercise in the upright and supine positions. METHODS: Sixteen healthy male volunteers (aged 32-46 yr; mean age 37 +/- 4 yr) were studied. All volunteers underwent ergometer exercise testing in both the upright and supine positions, and left ventricular performance was determined with the VEST system. RESULTS: The resting heart rate, systolic blood pressure, pressure rate product, relative end-diastolic volume, relative end-systolic volume and left ventricular ejection fraction (LVEF) all showed no differences between the upright and supine positions. At peak exercise, the heart rate, systolic blood pressure and pressure rate product showed no differences between the upright and supine positions. In the upright position at peak exercise the relative end-diastolic volume was increased (83% +/- 9% to 91% +/- 11%, p < 0.001); the relative end-systolic volume remained unchanged (34% +/- 3% to 33% +/- 15%), and LVEF was significantly increased from 58% +/- 6% to 66% +/- 11% (p < 0.01). In the supine position at peak exercise, the relative end-diastolic volume remained unchanged (85% +/- 5 to 83% +/- 7%), the relative end-systolic volume was increased (35% +/- 5% to 43% +/- 13%, p < 0.01), and LVEF was decreased from 58% +/- 5% to 48% +/- 17% (p < 0.01). These results indicated inferior data collection by the VEST system in the supine position. CONCLUSION: Since the detector of the VEST system may be too small, the data collection is impaired during exercise in the supine position by shifting the heart with deep respiration. The VEST system is very useful for determining left ventricular performance when applied in the sitting or upright position. However, in the supine position during exercise, the use of the VEST system should be avoided because it might indicate an artifactual deterioration of left ventricular performance.

Adult↗
PubMed1996

[A case of ventricular septal defect closure in patient with cytomegalo virus hepatitis].

Cytomegalovirus (CMV) infection has been reported to cause serious event in nonimmunocompromised patients after major surgery. Particularly in active case, the indication of surgical intervention is a difficult issue. A 7-months-old boy with ventricular septaldefect (VSD) has been diagnosed with CMV hepatitis. As his heart failure was not controlled with medication, he underwent closure of VSD at 9 months of age while CMV was still detected in the urine and serum by polymerase chain reaction method. During post operative course, he was treated with ganciclovir and intravenous CMV hyperimmune grobiln, and CMV in the serum became negative and he develops no aggravation of the CMV infection postoperatively.

Antiviral Agents↗
PubMed1995

Light chain loss and reexpression leads to idiotype switch. Surrogate light chains are probably responsible for this process.

The murine B-lymphocyte cell line 38C-13 is characterized by several cell surface markers typical for an early stage of B-cell differentiation. Cells of this cell line possess cell surface membrane IgM molecules composed of mu and kappa polypeptide chains. They also produce "surrogate" or "pseudo" light chains (psi L) coded by the lambda 5 and VpreB genes. Variants of the 38C-13 cell line which do not synthesize kappa chains can be isolated from the 38C-13 population by the use of anti-idiotype antibodies in vivo and in vitro. In some kappa chain-deficient variant cell lines, cells which have regained surface IgM expression but have lost the original idiotype specificity, can be isolated. This idiotype switch is probably due to a secondary rearrangement of the kappa gene. In the kappa chain-deficient variant cells, the mu chains assemble with the surrogate light chains but the assembled IgM-like molecules are not expressed on the cell surface. It is suggested that surrogate light chains play an important role in the induction of kappa gene rearrangement but that surface expression of mu-psi L complexes is not required for this process.

Animals↗
PubMed1993

Different assembly species of IgM are directed to distinct degradation sites along the secretory pathway.

In 38C B lymphocytes the membrane form of IgM is displayed on the cell surface whereas the secretory form of IgM is degraded. In the EH cell line, a light chain-deficient variant of 38C cells, the mu heavy chains are partially assembled with surrogate light chains characteristic of pre-B cells. In these cells neither the membrane (microns) nor the secretory (microsecond) forms of the mu heavy chain reach their final destination, and both are rapidly degraded. The degradation of mu chains in EH cells, like that of microsecond in 38C cells, is nonlysosomal and occurs prior to the trans-Golgi. However, while microsecond degradation in 38C cells is inhibited by brefeldin A, in EH cells microsecond and micron are retained and degraded by a brefeldin A-insensitive mechanism. These results indicate that degradation in EH cells occurs within the endoplasmic reticulum, whereas degradation in 38C cells requires exit from this compartment. Thus, mu heavy chains can be degraded in multiple sites along the secretory pathway. The location of the degradation process is determined by the developmentally regulated assembly species of the mu chains with either "classical" or surrogate light chains.

Animals↗
PubMed1993

Quantification of interleukin-1 in nasal polyps from patients with chronic sinusitis.

We have measured interleukin-1 alpha (IL-1 alpha) and beta levels in nasal polyps (NP) from patients with chronic sinusitis (CS) in order to determine their significance in the pathogenesis of NP. NP in ten cases (five male and five female; age range, 17-63 years) were removed to separate mononuclear (M) and polymorphonuclear (PMN) fractions through Ficoll-Paque separation media. ELISA measurements of the M fraction showed that the mean value of IL-1 beta was 17.8 pg/ml per gram, which was significantly higher than that of IL-1 alpha (7.04 pg/ml per gram, P < 0.01, Wilcoxon test). In the PMN fraction, the mean value of IL-1 alpha was 8.79 pg/ml per gram and that of IL-beta was 7.85 pg/ml per gram, which was not significantly different. Mononuclear leukocytes, particularly activated monocytes, seem to be a major source of IL-1 in the NP taken from patients with CS.

Adolescent↗