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Teruo Fujii

Publications and source records attributed to Teruo Fujii.

9 recordsLinked to original sources
PubMed2006

Characterization of a microfluidic dispensing system for localised stimulation of cellular networks.

We present a 3-D microfluidic device designed for localized drug delivery to cellular networks. The device features a flow cell comprising a main channel for nutrient delivery as well as multiple channels for drug delivery. This device is one key component of a larger, fully integrated system now under development, based upon a microelectrode array (MEA) with on-chip CMOS circuitry for recording and stimulation of electrogenic cells (e.g. neurons, cardiomyocytes). As a critical system unit, the microfluidics must be carefully designed and characterized to ensure that candidate drugs are delivered to specific regions of the culture at known concentrations. Furthermore, microfluidic design and functionality is dictated by the size, geometry, and material/electrical characteristics of the CMOS MEA. Therefore, this paper reports on the design considerations and fabrication of the flow cell, including theoretical and experimental analysis of the mass transfer properties of the nutrient and drug flows, which are in good agreement with one another. To demonstrate proof of concept, the flow cell was mounted on a dummy CMOS chip, which had been plated with HL-1 cardiomyocytes. A test chemical compound was delivered to the cell culture in a spatially resolved manner. Envisioned applications of this stand-alone system include simultaneous toxicological testing of multiple compounds and chemical stimulation of natural neural networks for neuroscience investigations.

Algorithms↗
PubMed2006

Controlling the expression ratio of two proteins by inserting a terminator between the two genes.

An approach was developed in controlling the expression ratio of two genes encoded in DNA by inserting a terminator sequence between the two genes. Escherichia coli ribosomal RNA operon T1 terminator, or E. coli tryptophane attenuater was introduced between two green fluorescent protein (GFP) mutants: ultraviolet-optimized mutant (GFPuv: F99S, M153T, V163A) and blue-shifted mutant (BFP: F64L, S65T, T145F). The ratio of the fluorescence intensity of BFP to GFPuv after transcription and translation reflected the termination efficiency of the transcriptional termination activity of the inserted terminator.

Escherichia coli↗
PubMed2005

Determination of the termination efficiency of the transcription terminator using different fluorescent profiles in green fluorescent protein mutants.

An approach in determining the intrinsic termination efficiency (%T) of transcription termination using green fluorescent protein (GFP) mutants was developed. This approach utilizes a cassette vector in which the tested terminator is introduced between two GFP mutant genes: an ultraviolet-optimized mutant (GFPuv: F99S, M153T, V163A) and a blue-shifted mutant (BFP: F64L, S65T, T145F). The ratio of the fluorescence intensity of BFP to GFPuv after transcription and translation represents the termination efficiency of the terminator. E. coli ribosomal RNA operon T1 terminator, phage lambda terminator site R2, E. coli tryptophane attenuater were introduced into the vector, and their transcriptional efficiencies were estimated as 89, 79, and 24%, respectively, showing good agreement with published data.

Base Sequence↗
PubMed2004

Hidden symmetry in chains of biological coupled oscillators.

We experimentally investigated spatiotemporal patterns in chains of coupled biological oscillators with boundaries and found hidden symmetric patterns that are not straightforwardly derived from explicit geometrical symmetry of the systems. We propose a model of coupled oscillators in chains with a hidden oscillator interconnecting its boundaries. The model can explain all observed patterns including the hidden symmetric ones, while other models such as discrete analogs of Neumann boundary conditions in continuous systems cannot.

Biological Clocks↗
PubMed2004

Membrane-based PDMS microbioreactor for perfused 3D primary rat hepatocyte cultures.

To improve primary adult rat hepatocyte cultures, two types of PDMS microbioreactors containing a membrane, used as a scaffold for the attachment of cells, were built: one with a commercially-available polyester membrane, the other with a PDMS membrane (5 x 5 microm hole sizes) made in our laboratory. In that way, the relative surface area between blood perfusion and hepatocytes seen in vivo was mimicked and as cells were bathed in both sides by the culture medium they expressed much higher functions. A new technique to build such PDMS membrane was created. With this technique we could build various PDMS membranes with down to 5 x 5 microm holes and with thickness even below 20 microm. During the fifteen days of perfusion in these microbioreactors, good cell attachment then cell reorganization was observed. Moreover compared to static cultures in tissue-culture-treated dishes and in cultures in inserts with the same polyester membranes, seven and two times increases in the albumin secretion by the cultured primary rat adult hepatocyte were demonstrated, respectively. Ammonium removal also increased 7 times in perfused cultures compared to static cultures. These new microbioreactors, which closely mimic the in vivo liver architecture, revealed themselves to be very promising tools towards future applications in drug screening or liver tissue engineering.

Animals↗
PubMed2003

A plug and play microfluidic device.

Chip-to-world interface is a major issue in the field of microfluidics and its applications. We developed a plug and play microfluidic device composed of a fluid driving unit and a polymer chip containing microfluidic channels and reservoirs. The one and only connection of the device to the external world is a set of electric control lines for the driving unit. Just putting the reagents and samples onto the reservoirs, the chip can be operated for chemical or biochemical reaction and analysis. We demonstrate here that silicon-based micropumps embedded in the present device allow us to achieve flexible fluidic manipulations with minimum time delay and dead volume.

Animals↗
PubMedDate not supplied

Phylogenetic diversity of dissimilatory sulfite reductase genes from deep-sea cold seep sediment.

The phylogenetic diversity of dissimilatory sulfite reductase (DSR, EC 1.8.99.3) alpha-subunit genes from a deep-sea cold seep was analyzed. Bulk genomic DNA was extracted from the cold seep sediment and used for amplification by polymerase chain reaction (PCR) of DSR alpha-subunit gene. Two sizes of PCR products, 1.4 kb (expected) and 1.3 kb (unexpected), were amplified. Sixteen clones of the 1.4-kb amplicons and 16 clones of 1.3-kb amplicons, a total of 32 clones, were obtained and grouped into operational DSR units (ODUs) based on restriction fragment length polymorphism (RFLP) by digestion with HaeIII and MboI. A total of 14 ODUs, i.e., 5 ODUs from 1.4-kb amplicon clones and 9 ODUs from 1.3-kb amplicon clones, were recovered. About 400 bp of the 5' ends of all the clones was sequenced and validated the RFLP-based ODU grouping. All the 5'-end 400-bp sequences of ODUs, even from the 1.3-kb amplicons, showed the characteristic DSR amino acid sequence motifs. The ODUs from 1.4-kb amplicons were closely related to the delta-Proteobacterial lineage with the DSR genes from epsilon-Proteobacterial epibionts of the hot vent worm Alvinella pompejana. The ODUs from 1.3-kb amplicons were mostly related to the unknown but possibly archaeal lineage. The diversity of the DSR genes may indicate the diversity of sulfate reducers in the seep sediment as well as the complexity of electron donors including methane.

Amino Acid Sequence↗
PubMedDate not supplied

Microfluidic PDMS (polydimethylsiloxane) bioreactor for large-scale culture of hepatocytes.

Microfluidics could provide suitable environments for cell culture because of the larger surface-to-volume ratio and fluidic behavior similar to the environments in vivo. Such microfluidic environments are now used to investigate cell-to-cell interactions and behaviors in vitro, emulating situations observed in vivo, for example, microscale blood vessels modeled by microfluidic channels. These emulated situations cannot be realized by conventional technologies. In our previous works, microfluidic channels composed of two PDMS (poly(dimethylsiloxane)) layers were successfully used for Hep G2 cell culture. To achieve physiologically meaningful functions in vitro, a culture with a larger number of cells and higher density must be performed. This will require bioreactors with larger surface areas for cell attachment and sufficient amounts of oxygen and nutrition supply. For those purposes, we fabricated a bioreactor by stacking 10 PDMS layers together, i.e., four cell culture chambers, and a chamber dedicated to the oxygen supply inserted in the middle of the 10-stacked layers. The oxygen supply chamber is separated from the microfluidic channels for the culture medium perfusion by thin 300-microm PDMS walls. The high gas permeability of PDMS allows oxygen supply to the microfluidic channels through the thin walls. On the basis of the measurement of glucose consumption and albumin production, it is shown that cellular activity exhibits a gradual increase and saturation throughout the culture. We clearly observed that in the case of the microfluidic bioreactor for large-scale cultures, the oxygen chamber is indispensable to achieve longer and healthy cultures. In the present bioreactor, the cell density was found to be about 3-4 x 10(7) cells/cm(3), which is in the same order of magnitude as the conventional macroscale bioreactors. Consequently, by stacking single culture chambers and oxygen chambers in between, we could have a scalable method to realize the microfluidic bioreactor for large-scale cultures.

Albumins↗