Measurement of electrode-tissue interface impedance for improvement of a transcutaneous data transmission using human body as transmission medium.

The electrical property between an electrode and skin or tissue is one of the important issues for communication performance of the transcutaneous communication system (TCS) using a human body as a conductive medium.In this study, we used a simple method to measure interface resistance between the electrode and skin on the surface of the body. The electrode-electrode impedance was measured by a commercially available LCR meter with changes in the distance between two electrodes on an arm of a healthy male subject, and we obtained the tissue resistivity and electrode-skin interface resistance using the cross-sectional area of the arm.We also measured transmission gain of the TCS on the surface of the body, and we investigated the relationship between electrode-skin interface resistance and transmission gain. We examined four kinds of electrodes: a stainless steel electrode, a titanium electrode, an Ag-AgCl electrode and an Ag-AgCl paste electrode. The stainless steel electrode, which had lower electrode-skin resistance, had higher transmission gain.The results indicate that an electrode that has lower electrode-skin resistance will contribute to improvement of the performance of the TCS and that electrode-skin interface resistance is one of valuable evaluation parameters for selecting an optimum electrode for the TCS.

A new transcutaneous bidirectional communication for monitoring implanted artificial heart using the human body as a conductive medium.

A transcutaneous communication system (TCS) is a key technology for monitoring and controlling artificial hearts and other artificial organs in the body. In this study, we developed a new TCS that uses the human body as a conductive medium. Direct data exchange provides a higher level of communication security compared to that of wireless methods without physical constraints such as an external wire. The external and internal units of the new TCS each consist mainly of a data transmitter and a data receiver. The data transmitter has an amplitude shift keying (ASK) modulator (carrier frequencies: 4 and 10 MHz) and an electrode. The ASK-modulated data current is led into the body through the electrode, and it flows back to the energy source through the body, the data receiver, and the earth ground that includes all conductors and dielectrics in the environment that are in close proximity to the patient. Performance of the TCS was evaluated by a communication test on the surface of the human body and in an animal experiment using a goat. The TCS was able to transmit data concurrently for 4 weeks between everywhere on the surface of the body and everywhere inside the body under full-duplex communication at a transmission rate of 115 kbps. The power consumption of each TCS unit was 125 mW with an ASK-modulated current of 7 mA (root-mean-square). While further study is required to secure its safety, the newly developed TCS has promise to be a next-generation transcutaneous communication device.

Interface of data transmission for a transcutaneous communication system using the human body as transmission medium.

We have been developing a new transcutaneous communication system (TCS) that uses the human body as an electrical conductive medium. We studied an interface circuit of the TCS in order to optimize the leading data current into the human body effectively. Two types of LC circuits were examined for the interface circuit, one was an LC series-parallel circuit, and the other was a parallel-connected LC circuit. The LC series-parallel circuit connected to the body could be tuned to a resonant frequency, and the frequency was determined by the values of an external inductor and an external capacitor. Permittivity of the body did not influence the electrical resonance. Connection of the LC series-parallel circuit to the body degraded the quality factor Q because of the conductivity of the body. However, the LC parallel-connected circuit when connected to the body did not indicate electrical resonance. The LC series-parallel circuit restricts a direct current and a low-frequency current to flow into the body; thus, it can prevent a patient from getting a shock. According to the above results, an LC series-parallel circuit is an optimum interface circuit between the TCS and the body for leading data current into the body effectively and safely.

Basic study of a transcutaneous information transmission system using intra-body communication.

The transcutaneous communication system (TCS) is one of the key technologies for monitoring and controling artificial hearts and other artificial organs in the body. In this study, we have developed a new TCS that uses the human body as a conductive medium. Having no energy conversion from electric currents into electromagnetic waves and light provides energy-saving data transmission with a simple electrical circuit. Each unit of the TCS mainly consists of two electrodes, an amplitude shift keying (ASK) modulator and an ASK demodulator (carrier frequency: 4 and 10 MHz). A resonant frequency of an L-C tank circuit including the capacitance component of the body is tuned into each carrier frequency in order to apply the data current effectively into the body. Performance of the TCS was evaluated by a communication test on the surface of a human body. The TCS was able to transmit 3,315 bytes of data bi-directionally at a transmission rate of 115 kbps from a left wrist to a right forearm, to an abdomen and to a left calf without communication error. The power consumption of each TCS unit was 125 mW with an ASK modulated current of 7 mA (RMS). While further study is required to secure its safety, the TCS promises to be a next-generation transcutaneous communication device.

Overexpression of Septin1: possible contribution to the development of oral cancer.

Our previous study using proteomic profiling demonstrated significant up-regulation of Septin1, a conserved family of GTPase proteins, in oral squamous-cell carcinoma (OSCC)-derived cell lines. In the current study, to determine the potential involvement of Septin1 in oral carcinogenesis, we evaluated the state of septin1 protein/mRNA expression in OSCC-derived cell lines, oral premalignant lesions (OPLs), and primary OSCCs. A significant (P<0.05) increase in Septin1 expression was evident in all OSCC-derived cell lines examined compared to human normal oral keratinocytes (HNOKs) and OPLs. In immunohistochemistry, while the vast majority of the OSCCs (89%) were positive for Septin1, no immunoreaction was observed in corresponding normal tissues and OPLs. In addition, real-time quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR) data were consistent with the protein expression status. These results suggest that Septin1 expression could contribute to cancer progression, proliferation, or both, and that Septin1 may be a potential diagnostic marker of highly active cancer and a therapeutic target for OSCCs.

Genes and molecular pathways related to radioresistance of oral squamous cell carcinoma cells.

To identify genes associated with radioresistant oral squamous cell carcinoma (OSCC), we compared gene expression signatures between OSCC cell lines exhibiting radioresistance and cells with radiosensitivity after X-ray irradiation in a dose-dependent manner using Affymetrix GeneChip analysis with Human Genome-U133 plus 2.0 GeneChip. The microarray data identified 167 genes that were significantly overexpressed in radioresistant cells after X-ray irradiation. Among the genes identified, 40 were mapped to 3 highly significant genetic networks identified by the Ingenuity Pathway Analysis tool. Gene ontology analysis showed that cancer-related function had the highest significance. The 40 genes included 25 cancer-related genes that formed 1 network and were categorized by function into growth and proliferation, apoptosis, and adhesion. Furthermore, real-time quantitative reverse transcriptase-polymerase chain reaction showed that the mRNA expression levels of the 25 genes were higher in radioresistant cells than in radiosensitive cells in a dose-dependent manner and in a time-dependent manner. Our results suggest that the identified genes help to elucidate the molecular mechanisms of the radioresistance of OSCC and could be radiotherapeutic molecular markers for choosing the appropriate radiotherapy for this disease.

Gene expression pattern in oral cancer cervical lymph node metastasis.

Treatment protocols for malignant tumors in the oral cavity differ greatly based on the presence of cervical lymph node metastasis. We applied gene expression profiling to the pathological lymph node status and used a training-test approach to evaluate the reliability of cDNA microarray-based classifications of 15 matched resected primary oral squamous cell carcinomas (OSCCs) and corresponding normal oral tissues. The clustering of all the microarray data was separated into two groups based on metastatic node positivity and node negativity. Furthermore, a 20-gene signature was identified that differentiated the testing set (n=8) with high classification accuracy (88%). Our findings support the hypothesis that the lymph node metastasis status can be predicted using the gene expression patterns of the primary OSCC, and may be a powerful tool in identifying patients at high risk of lymph node metastasis.

Enhancement of SPHK1 in vitro by carbon ion irradiation in oral squamous cell carcinoma.

PURPOSE: The purpose of this study was to assess the gene expression changes in oral squamous cell carcinoma (OSCC) cells after carbon ion irradiation. METHODS AND MATERIALS: Three OSCC cell lines (HSC2, Ca9-22, and HSC3) were irradiated with accelerated carbon ion beams or X-rays using three different doses. The cellular sensitivities were determined by clonogenic survival assay. To identify genes the expression of which is influenced by carbon ion irradiation in a dose-dependent manner, we performed Affymetrix GeneChip analysis with HG-U133 plus 2.0 arrays containing 54,675 probe sets. The identified genes were analyzed using the Ingenuity Pathway Analysis Tool to investigate the functional network and gene ontology. Changes in mRNA expression in the genes were assessed by real-time reverse transcriptase-polymerase chain reaction. RESULTS: We identified 98 genes with expression levels that were altered significantly at least twofold in each of the three carbon-irradiated OSCC cell lines at all dose points compared with nonirradiated control cells. Among these, SPHK1, the expression of which was significantly upregulated by carbon ion irradiation, was modulated little by X-rays. The function of SPHK1 related to cellular growth and proliferation had the highest p value (p = 9.25e-7 to 2.19e-2). Real-time reverse transcriptase-polymerase chain reaction analysis showed significantly elevated SPHK1 expression levels after carbon ion irradiation (p < 0.05), consistent with microarray data. Clonogenic survival assay indicated that carbon ion irradiation could induce cell death in Ca9-22 cells more effectively than X-rays. CONCLUSIONS: Our findings suggest that SPHK1 helps to elucidate the molecular mechanisms and processes underlying the biologic response to carbon ion beams in OSCC.

Down-regulation of 1D-myo-inositol 1,4,5-trisphosphate 3-kinase A protein expression in oral squamous cell carcinoma.

Functional proteomics is a useful method to explore changes in protein expression in human diseases, including carcinomas. To identify tumor-associated proteins as biomarkers or molecular targets of human oral squamous cell carcinomas (OSCCs), we performed two-dimensional polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Comparison of the protein expression profiles of OSCC cell lines and normal oral keratinocytes identified six proteins with markedly different expression levels. Of the six proteins, we found a 1D-myo-inositol 1,4,5-trisphosphate 3-kinase A (ITPKA) protein that was down-regulated in OSCC cell lines. ITPKA phosphorylates inositol 1,4,5-trisphosphate, which regulates the calcium (Ca2+) level within the cell by releasing Ca2+ from intracellular stores, and is responsible for regulating the levels of a large number of inositol polyphosphates that are important in cellular signaling. Western blots revealed dramatically down-regulated ITPKA expression in all OSCC cell lines examined. Real-time quantitative reverse transcriptase-polymerase chain reaction showed down-regulated ITPKA mRNA expression in nine of 12 (75%) OSCC cell lines. Immunohistochemistry analysis showed that 40 of 100 OSCC clinical samples had a significant decrease in ITPKA. Poorly differentiated tumors showed significantly lower immunoreactivity of the protein compared to well- and moderately-differentiated tumors. These data suggest that ITPKA may be related to carcinogenesis by the modulation of inositol polyphosphates and Ca2+ homeostasis and that ITPKA may be a potential novel molecular target, biomarker, parameter, or all of these of cellular differentiation and of intracellular Ca2+ homeostatic characteristics in clinical medicine.

Plasma membrane Ca2+ ATPase isoform 1 down-regulated in human oral cancer.

The plasma membrane Ca(2+) ATPase (PMCA) is an essential regulator of free intracellular calcium. Recent studies have reported aberrant expression of the PMCA1 gene, a member of the PMCA family, in several cancer cell types. To elucidate the contribution of PMCA1 to oral carcinogenesis, we analyzed genetic and epigenetic changes and mRNA and protein expression in primary oral squamous cell carcinomas (OSCCs), oral premalignant lesions (OPLs), and OSCC-derived cell lines. The PMCA1 gene was epigenetically inactivated, but not mutated in the eight OSCC-derived cell lines tested. In clinical samples, frequent down-regulation of PMCA1 protein expression was found not only in primary OSCCs (43%), but also in OPLs (40%). Real-time quantitative reverse transcriptase-polymerase chain reaction data were consistent with the protein expression status. These results suggest that inactivation of the PMCA1 gene is a frequent and early event during oral carcinogenesis, and gene expression may be regulated by an epigenetic mechanism.

Identification of differentially expressed proteins in oral squamous cell carcinoma using a global proteomic approach.

A number of protein markers for oral cancer are still not applicable in large populations. Proteomic technologies provide excellent tools for rapid screening of a large number of potential biomarkers in malignant cells. To gain insight into the molecular mechanisms of carcinogenesis and to identify potential biomarkers for oral squamous cell carcinomas (OSCCs), we performed proteomic profiling between human normal oral keratinocytes (HNOKs) and OSCC-derived cell lines (HSC-2 and HSC-3) using fluorescent two-dimensional difference in-gel electrophoresis. Proteins with a > or =2-fold change in expression were considered significant. The spots of interest were digested and identified by matrix-assisted laser desorption/ionization time-of-flight peptide mass finger-printing. Twenty-two proteins were identified as differentially expressed between the HNOKs and OSCC-derived cell lines. Of these, 9 spots were up-regulated and 13 were down-regulated in OSCC-derived cell lines compared to the HNOKs. These spots included the cancer-related proteins; annexin A1, heat shock protein 27, lamin A/C, interleukin 1 receptor antagonist, serine proteinase inhibitor clade B5, stathmin 1, and superoxide dismutase 2. Our results are a first step toward identifying a protein profile of HNOKs and OSCC-derived cell lines. The identified proteins in this experiment may be used in future studies of carcinogenesis or as diagnostic markers and therapeutic targets for OSCC.