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Biomedical subjects

Kenji Yasuda

Publications and source records attributed to Kenji Yasuda.

At least 19 recordsLinked to original sources
PubMed2006

Methodological improvements of pyrosequencing technology.

Pyrosequencing technology is a rather novel DNA sequencing method based on the sequencing-by-synthesis principle. This bioluminometric, real-time DNA sequencing technique employs a cascade of four enzymatic reactions producing sequence peak signals. The method has been proven highly suitable for single nucleotide polymorphism analysis and sequencing of short stretches of DNA. Although the pyrosequencing procedure is relatively straightforward, users may face challenges due to varying parameters in PCR and sequencing primer design, sample preparation and nucleotide dispensation; such challenges are labor and cost intensive. In this study, these issues have been addressed to increase signal quality and assure sequence accuracy.

Base Sequence↗
PubMed2006

Fluorescence microscopic investigation on morphological changes of giant multilamellar vesicles induced by amphiphilic additives.

Adding an artificial bolaamphiphile to a dispersion of giant multilamellar vesicles (GMVs) made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) induced a cup-shaped deformation in GMVs accompanied by partial extrusion of the inner vesicle; thereafter, the deformed vesicles returned to their original shape. On the other hand, when the artificial bolaamphiphile together with a surfactant was added to the vesicular dispersion, these deformation and reformation dynamics were transmitted from the outer membranes in GMVs to the inner membranes until an intact inner vesicle was extruded out of the outer membrane. The microscopic aspects of these processes were investigated using amphiphiles tagged with individual fluorophores.

Journal Article↗
PubMed2006

Effects of postural change on oxygen saturation and respiration in patients after the Fontan operation: platypnea and orthodeoxia.

The aim of this study was to assess whether platypnea and orthodeoxia occur in Fontan patients. We divided 14 Fontan patients into 2 groups: 8 patients who had pulmonary arteriovenous fistulas and/or intra-atrial shunts (group A) and 6 patients who had neither pulmonary arteriovenous fistulas nor intra-atrial shunts (group B). They were compared with 9 controls (group C). Arterial oxygen saturation, minute ventilation per body weight and ventilatory equivalent for carbon dioxide were measured in the supine and then sitting positions. In group A, 1 patient had platypnea and 3 patients had orthodeoxia (changes in the saturation from the supine position to the sitting position were -4% to -7%) accompanied with slight hyperpnea, and all 4 patients had both pulmonary arteriovenous fistulas and intra-atrial shunts. Contrary, patients in group B had neither platypnea nor orthodeoxia. The saturation was significantly lower and the minute ventilation was significantly higher in the sitting position than in the supine position in group A (p < 0.05). The other groups showed no significant difference in the saturation or the minute ventilation between the 2 positions. All groups showed the ventilatory equivalent was significantly higher in the sitting position than in the supine position (p < 0.05 to 0.01). We demonstrated platypnea and orthodeoxia in Fontan patients with pulmonary arteriovenous fistulas and intra-atrial shunts. We believe platypnea and orthodeoxia should be regard as a complication in Fontan patients with pulmonary arteriovenous fistulas and/or intra-atrial shunts.

Adolescent↗
PubMed2006

Oral immunoadjuvant activity of Lactobacillus casei subsp. casei in dextran-fed layer chickens.

We recently reported that synbiotic Lactobacillus casei subsp. casei together with specific substrate dextran elicited an enhancement in humoral immune response against bovine serum albumin (BSA) as a model antigen in BALB/c mice. The present study was designed to evaluate the oral immunoadjuvant effects of the synbiotic in layer chickens. Using a PCR assay, L. casei subsp. casei was detected specifically in the intestinal chyme of chickens (10 d of age, Julia strain) fed ad libitum on a diet supplemented with 75 mg dextran/kg (dextran-supplemented diet, DSD) and administered orally with 10(7) colony-forming units (CFU) L. casei subsp. casei in 0.1 ml PBS with the aid of an intubation needle at 1, 2 and 3 d of age. Furthermore, oral administration of 10(7) CFU L. casei subsp. casei at 1-3 d of age significantly enhanced the production of anti-BSA antibody in DSD-fed chickens (60 d of age) administered orally with 1 mg BSA at 32 and 33 d of age and subcutaneously with 5 microg BSA at 33 d of age. In addition, among bacterial numbers tested, 10(6) CFU L. casei subsp. casei together with dextran induced an effective increase in humoral immune response to mixed inactivated vaccines against Newcastle disease and avian infectious bronchitis, and the treatment may be advantageous in protecting against these infectious diseases in chickens in actual application. These results suggest that dietary supplementation of L. casei subsp. casei with dextran leads to immunomodulation of humoral immune responses.

Adjuvants, Immunologic↗
PubMed2006

A new synbiotic, Lactobacillus casei subsp. casei together with dextran, reduces murine and human allergic reaction.

We studied the development of atopic dermatitis-like skin lesions in NC/Nga mice and the allergic symptoms and blood patterns of healthy volunteers during the cedar (Cryptomeria japonica) pollen season in Japan following oral administration of a new synbiotic, Lactobacillus casei subsp. casei together with dextran. The combination of L. casei subsp. casei and dextran significantly decreased clinical skin severity scores and total immunoglobulin E levels in sera of NC/Nga mice that had developed picryl chloride-induced and Dermatophagoides pteronyssinus crude extract-swabbed atopic dermatitis-like skin lesions. During the most common Japanese cedar pollen season, synbiotic L. casei subsp. casei and dextran in humans led to no significant changes in total nasal and ocular symptom scores, in the levels of cedar pollen-specific immunoglobulin E, interferon-gamma and thymus and activation regulated chemokine or in the number of eosinophils in sera, whereas the placebo group showed a tendency for increased levels of cedar pollen-specific immunoglobulin E, thymus and activation regulated chemokine and number of eosinophils, and a decrease in interferon-gamma levels. Thus, the oral administration of synbiotic L. casei subsp. casei together with dextran appears to be an effective supplement for the prevention and treatment of allergic reactions.

Adult↗
PubMed2005

Stability of beating frequency in cardiac myocytes by their community effect measured by agarose microchamber chip.

To understand the contribution of community effect on the stability of beating frequency in cardiac myocyte cell groups, the stepwise network formation of cells as the reconstructive approach using the on-chip agarose microchamber cell microcultivation system with photo-thermal etching method was applied. In the system, the shapes of agarose microstructures were changed step by step with photo-thermal etching of agarose-layer of the chip using a 1064-nm infrared focused laser beam to increase the interaction of cardiac myocyte cells during cultivation. First, individual rat cardiac myocyte in each microstructure were cultivated under isolated condition, and then connected them one by one through newly-created microchannels by photo-thermal etching to compare the contribution of community size for the magnitude of beating stability of the cell groups. Though the isolated individual cells have 50% fluctuation of beating frequency, their stability increased as the number of connected cells increased. And finally when the number reached to eight cells, they stabilized around the 10% fluctuation, which was the same magnitude of the tissue model cultivated on the dish. The result indicates the importance of the community size of cells to stabilize their performance for making cell-network model for using cells for monitoring their functions like the tissue model.

Journal Article↗
PubMed2005

Single-cell growth and division dynamics showing epigenetic correlations.

The emergence of variation and subsequent inheritance of the emergent characteristics in a clonal population of bacteria is considered as evidence for epigenetic processes in the cell. We report here the results of experiments in which we quantitatively examined variations in single Escherichia coli cells with an identical genetic endowment in order to establish whether certain characteristics of single cells were inherited by their descendants maintained in a uniform environment. Significantly large variations of interdivision time, initial length, and final length were observed from generation to generation. Comparing the generations shows that interdivision time had no correlation with that of the consecutive generations, whereas those of initial length and final length were positively correlated with those of neighbouring generations.

Bacteriological Techniques↗
PubMed2005

Genetic variation of a fimbrial protein from Porphyromonas gingivalis and its distribution in patients with periodontal diseases.

Pg-II fim from various strains of Porphyromonas gingivalis was classified on the basis of each nucleotide sequence, while the distribution of Pg-II fim types in 141 subgingival plaque samples was analyzed using PCR assays. Pg-II fim was divided into two types as follows: strains OMZ409, HG405, 381, ATCC 33277 and BH18/10 (type 1) and strains OMZ314 and HW24D-1 (type 2). The presence of P. gingivalis was demonstrated in 2.8% of healthy subjects and 56.1% of patients with periodontal diseases, and Pg-II fim was detected in 91.8% of the P. gingivalis-positive subjects. We also analyzed the distribution of the Pg-II fim types among Pg-II fim-positive patients, with the following results: type 1 (38.2%), type 2 (56.4%) and types 1 and 2 (5.4%). These findings strongly suggest that P. gingivalis organisms possessing Pg-II fim type 2 was principally detected in patients with periodontal diseases.

Adolescent↗
PubMed2005

Dilated cardiomyopathy after pacemaker implantation in complete heart block.

BACKGROUND: The aim of this study was to evaluate the clinical features of patients with congenital complete heart block (CCHB) who developed dilated cardiomyopathy (DCM) after pacemaker implantation (PMI) and to determine factors predicting DCM development. METHOD: A total of 15 patients were reviewed retrospectively. They were classified into two groups, one consisted of four patients who were diagnosed as having CCHB in utero or at birth and who developed DCM after PMI (DCM group) and the other consisted of 11 patients who did not (non-DCM group). RESULTS: Maternal autoantibodies were found in two of the DCM group and in five of the non-DCM group. Perfusion defects in myocardial imaging were detected in all DCM patients and in five non-DCM patients. DCM developed 2 to 43 months after PMI and three DCM patients died of heart failure 7 to 48 months after PMI. In pathological studies, endocardial or interstitial fibrosis was present in all DCM patients and in one of two in the non-DCM group. No significant differences between the two groups were found in age at PMI, atrial or ventricular rate, end-diastolic dimension and ejection fraction of the left ventricle before PMI, and width of QRS after PMI. CONCLUSION: Although it was suspected that the patients with CCHB had myocardial involvement before PMI, there was no significant factor predicting the risk of DCM after PMI. In addition to cardiac rhythm abnormalities, careful attention should be paid to cardiac function in CCHB patients after PMI.

Cardiomyopathy, Dilated↗
PubMed2004

Stepwise pattern modification of neuronal network in photo-thermally-etched agarose architecture on multi-electrode array chip for individual-cell-based electrophysiological measurement.

We have developed a procedure for stepwise topographical control of network patterns and neurite connection directions between adjacent living neurons using an individual-cell-based on-chip multi-electrode array (MEA) cell cultivation system with an agarose microchamber (AMC) array. This procedure enables flexible and precise control of the cell positions and easy and flexible control of the pattern modification of connections between the cells in AMCs through stepwise photo-thermal etching in which a portion of the agarose layer on the chip is melted with a 1480 nm infrared laser beam even during cultivation. With adequate laser power and this stepwise procedure, we can fabricate narrow micrometer-order grooves (microchannels) during cultivation in a stepwise manner. Using this procedure, we controlled the direction of elongation of axons and dendrites selectively and confirmed the direction by immunostaining. We also demonstrated electrophysiological one-way transmission of signals among aligned hippocampal neurons in which the directions of the neurite connections were controlled using this stepwise photo-thermal etching procedure. These results demonstrate the potential of full direction control of neurite connections between neurons using stepwise photo-thermal etching to form microchannels one by one in an on-chip AMC/MEA cell cultivation system. We can thus better understand the meaning of neuronal network patterns and connection directions.

Animals↗
PubMed2004

Biotechnology approach to determination of genetic and epigenetic control in cells.

A series of studies aimed at developing methods and systems for analyzing epigenetic information in cells are presented. The role of the epigenetic information of cells, which is complementary to their genetic information, was inferred by comparing the predictions of genetic information with the cell behaviour observed under conditions chosen to reveal adaptation processes and community effects. Analysis of epigenetic information was developed starting from the twin complementary viewpoints of cells regulation as an 'algebraic' system (emphasis on the temporal aspect) and as a 'geometric' system (emphasis on the spatial aspect). The knowlege acquired from this study will lead to the use of cells for fully controlled practical applications like cell-based drug screening and the regeneration of organs.

Journal Article↗
PubMed2004

A novel method of cultivating cardiac myocytes in agarose microchamber chips for studying cell synchronization.

We have developed a new method that enables agar microstructures to be used to cultivate cardiac myocyte cells in a manner that allows their connection patterns to be controlled. Non-contact three-dimensional photo-thermal etching with a 1064-nm infrared focused laser beam was used to form the shapes of agar microstructures. This wavelength was selected as it is not absorbed by water or agar. Identical rat cardiac myocytes were cultured in adjacent microstructures connected by microchannels and the interactions of asynchronous beating cardiac myocyte cells observed. Two isolated and independently beating cardiac myocytes were shown to form contacts through the narrow microchannels and by 90 minutes had synchronized their oscillations. This occurred by one of the two cells stopping their oscillation and following the pattern of the other cell. In contrast, when two sets of synchronized beating cells came into contact, those two sets synchronized without any observable interruptions to their rhythms. The results indicate that the synchronization process of cardiac myocytes may be dependent on the community size and network pattern of these cells.

Journal Article↗
PubMed2004

Modification of a neuronal network direction using stepwise photo-thermal etching of an agarose architecture.

Control over spatial distribution of individual neurons and the pattern of neural network provides an important tool for studying information processing pathways during neural network formation. Moreover, the knowledge of the direction of synaptic connections between cells in each neural network can provide detailed information on the relationship between the forward and feedback signaling. We have developed a method for topographical control of the direction of synaptic connections within a living neuronal network using a new type of individual-cell-based on-chip cell-cultivation system with an agarose microchamber array (AMCA). The advantages of this system include the possibility to control positions and number of cultured cells as well as flexible control of the direction of elongation of axons through stepwise melting of narrow grooves. Such micrometer-order microchannels are obtained by photo-thermal etching of agarose where a portion of the gel is melted with a 1064-nm infrared laser beam. Using this system, we created neural network from individual Rat hippocampal cells. We were able to control elongation of individual axons during cultivation (from cells contained within the AMCA) by non-destructive stepwise photo-thermal etching. We have demonstrated the potential of our on-chip AMCA cell cultivation system for the controlled development of individual cell-based neural networks.

Journal Article↗
PubMed2004

Non-destructive on-chip cell sorting system with real-time microscopic image processing.

Studying cell functions for cellomics studies often requires the use of purified individual cells from mixtures of various kinds of cells. We have developed a new non-destructive on-chip cell sorting system for single cell based cultivation, by exploiting the advantage of microfluidics and electrostatic force. The system consists of the following two parts: a cell sorting chip made of poly-dimethylsiloxane (PDMS) on a 0.2-mm-thick glass slide, and an image analysis system with a phase-contrast/fluorescence microscope. The unique features of our system include (i) identification of a target from sample cells is achieved by comparison of the 0.2-microm-resolution phase-contrast and fluorescence images of cells in the microchannel every 1/30 s; (ii) non-destructive sorting of target cells in a laminar flow by application of electrostatic repulsion force for removing unrequited cells from the one laminar flow to the other; (iii) the use of agar gel for electrodes in order to minimize the effect on cells by electrochemical reactions of electrodes, and (iv) pre-filter, which was fabricated within the channel for removal of dust contained in a sample solution from tissue extracts. The sorting chip is capable of continuous operation and we have purified more than ten thousand cells for cultivation without damaging them. Our design has proved to be very efficient and suitable for the routine use in cell purification experiments.

Journal Article↗
PubMed2004

Simultaneous measurement of sensor-protein dynamics and motility of a single cell by on-chip microcultivation system.

Measurement of the correlation between sensor-protein expression, motility and environmental change is important for understanding the adaptation process of cells during their change of generation. We have developed a novel assay exploiting the on-chip cultivation system, which enabled us to observe the change of the localization of expressed sensor-protein and the motility for generations. Localization of the aspartate sensitive sensor protein at two poles in Escherichia coli decreased quickly after the aspartate was added into the cultivation medium. However, it took more than three generations for recovering the localization after the removal of aspartate from the medium. Moreover, the tumbling frequency was strongly related to the localization of the sensor protein in a cell. The results indicate that the change of the spatial localization of sensor protein, which was inherited for more than three generations, may contribute to cells, motility as the inheritable information.

Journal Article↗
PubMed2004

Mixed feed containing dextran improves milk production of holstein dairy cows.

Total 37 Holstein daily cows (body weight: 631.76 +/- 18.45 kg, age: 5.47 +/- 1.94 years, parturition: 3.71 +/- 1.76 times) which became pregnant and gave birth to calves in the same season and lactated continuously were selected for this study. They were randomly divided into two groups: Group A-control, Group B-fed with 30 g/head/day of mixed feed containing supplemental dextran for one year from October 2001. After supplementation of the mixed feed, milk yields and components (fat, protein and solid non-fat) of Group B were compared with those of Group A in the 8th, 10th and 11th months (May, July and August of 2002). Milk yields of Group B were greater than the yields of Group A. In particular, there was a significant difference (p<0.001) between these groups in the July and August values. Milk components of Group B slightly differed from those of Group A before the supplementation, but after the supplementation, concentrations and total amounts of fat, protein and solid non-fat significantly increased more in Group B than in Group A. Thus mixed feed containing dextran can increase the milk production of Holstein dairy cows in the hot season.

Animal Feed↗
PubMed2003

Two-dimensional network formation of cardiac myocytes in agar microculture chip with 1480 nm infrared laser photo-thermal etching.

We have developed a new method that enables agar microstructures to be used to cultivate cells and that allows cell network patterns to be controlled. The method makes use of non-contact three-dimensional photo-thermal etching with a 1480 nm infrared focused laser beam, which is strongly absorbed by water and agar gel, to form the shapes of agar microstructures. It allows microstructures to be easily formed in an agar layer within a few minutes, with cell-culture holes formed by the spot heating of a 100 mW laser and tunnels by the tracing of a 100 microm s(-1), 40 mW laser. We cultivated rat cardiac myocytes in adjacent microstructures and observed synchronized beating in them 90 min after they had made physical contact. Our results indicate that the system can make and use microstructures for cell-network cultivation in a minimal amount of time without any expensive microfabrication facilities or complicated procedures.

Agar↗