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Surface resistivity is one of the most important properties in determining the electrostatic behavior of materials. We have previously developed a non-contact surface resistivity tester that uses surface potential rise time measurements along with corona charging. The system was used to successfully measure surface resistivities greater than 109 Ω. Because the lower limit of the rise time measurement was intrinsically determined by the response time of the surface voltmeter, it is difficult to extend the measurable range to lower than 109 Ω. In this study, a non-contact surface resistivity tester for materials from 107 to 1011 Ω was developed using a grid-type charge elimination apparatus, in addition to a corona charger and a surface voltmeter. The purpose of this design was to make both charging and non-charging spots on a test sample, which resulted in a steady current flow between the two spots. The steady surface potential between the two spots was measured without the influence of the surface voltmeter response time. The steady potential was determined to be a function of the surface resistivity in the range of 107–1011 Ω by solving an equivalent circuit model. The measured surface potential was in good agreement with the surface resistivity from 107 to 1011 Ω, as predicted by the circuit model.

Patient: Female, 85-year-old Final Diagnosis: Scirrhous gastric cancer • upside-down stomach Symptoms: Heartburn • loss of appetite • vomiting Medication: — Clinical Procedure: Surgery Specialty: Gastroenterology and Hepatology Objective: Mistake in diagnosis Background: The upper stomach can be involved in 1 type of esophageal hiatal hernia in which the degree of stomach insertion is considerable and accompanied by a twist in the shaft of the stomach. The diagnostic accuracy of upper endoscopy or barium meal examination decreases in patients with upside-down stomach, thus making diagnosis of stomach lesions very difficult. No previous reports have described scirrhous gastric cancer in a patient with upside-down stomach. Case Report: An 85-year-old woman presented with loss of appetite and vomiting after eating oxalic acid-containing food 2 months previously. Computed tomography revealed an upside-down stomach, and upper endoscopy revealed loss of distensibility and superficial gastritis of the entire stomach. Upside-down stomach was diagnosed; accordingly, laparoscopic hernia repair was planned. Laparoscopic exploration revealed retention of serous fluid (i.e., ascites) containing gastric carcinoma cells (pathologically identified intraoperatively) and induration of the entire stomach. After converting to laparotomy, induration of the stomach was confirmed, continuing to the adjacent 4 cm of the distal esophagus. The patient was diagnosed with scirrhous gastric cancer. Esophageal hiatus hernia repair was performed due to the patient’s age and the risks associated with esophagojejunostomy. Preoperative complaints of symptoms disappeared. The patient was transferred to the medical hospital on postoperative day 52 with no complications. Conclusions: Specific symptoms of gastric cancer can mimic those of esophageal hiatal hernia in patients with hernia. In cases of upside-down stomach with loss of distensibility and increased wall thickness, physicians should be aware of the possibility of scirrhous gastric cancer.

This paper proposes a method for applying three typical human impressions directly into product designs to fabricate products using 3D printers. The method automatically estimates human impressions of the three-dimensional shape of an item in terms of three representative sensibilities: “hard–soft,” “flashy–sober,” and “stable–volatile.” This technique can be used for new 3D fabrication processes that reflect the designer’s intentions directly into the shapes of products. To estimate the impressions of the shape of an object, we need to draw strong correlations between impressions, which are psychological factors, and the aspects of the shape of the object, which are physical factors. The method uses deep learning effectively to address this issue. The object being evaluated is first converted to a set of images by photographing it from 20 surrounding directions. This image set is used as input data for deep learning with parameters of human impressions of the object as supervisory signals. In experiments, we used original dataset of three-dimensional objects of a car with assigned impressions that had been quantified using the semantic differential (SD) method. The correlation coefficients between impressions estimated using this method and the supervisory signals for all the datasets were about 0.70 for “hard–soft,” about 0.61 for “flashy–sober,” and about 0.67 for “stable–unstable.”

Patient: Male, 70-year-old Final Diagnosis: Intravascular lymphoma • superior mesenteric vein thrombosis Symptoms: Abdominal pain Medication:— Clinical Procedure: Small intestine resection Specialty: Gastroenterology and Hepatology Objective: Unusual setting of medical care Background: Superior mesenteric vein thrombosis (SMVT) is a relatively rare form of acute abdominal disease; less than 0.1% of laparotomy surgeries are performed for SMVT. In the presence of severe intestinal ischemia or necrosis caused by SMVT, immediate surgical intervention is required. Macroscopic diagnosis of intestinal viability is sometimes difficult; its over-resection may carry the risk of short bowel syndrome. A near-infrared fluorescence imaging system with indocyanine green (ICG) has recently been developed for intraoperative, real-time evaluation of intestinal perfusion. This is the first report on the use of ICG fluorescence imaging during surgery for intestinal ischemia caused by venous thrombosis. Case Report: A 70-year-old man presented with a general feeling of weariness. On examination, he was diagnosed with intravascular large B cell lymphoma. R-CHOP therapy was initiated. On day 3 of initial R-CHOP therapy, the patient experienced sudden severe abdominal pain while in the hospital. Contrast-enhanced computed tomography revealed SMVT and loss of contrast effect in the small intestine. We diagnosed small bowel necrosis caused by SMVT, and exploratory laparotomy was performed, which revealed a continuous ischemia of 150 cm. Intraoperative ICG fluorescence imaging was utilized, and the color boundary was consistent with the ischemic area detected by visualization. The necrotic small intestine was excised and anastomosed. The patient was transferred to the hematology department on postoperative day 10 with no severe complications such as anastomotic leakage or re-thrombosis, and re-embolization was not observed 6 months later. Conclusions: Venous thrombosis should be listed as a differential diagnosis when acute abdominal disease presents during chemotherapy for malignant lymphoma. ICG fluorescence imaging may be useful in the evaluation of intestinal blood flow for venous thrombosis.

Patient: Male, 76-year-old Final Diagnosis: Appendiceal-colonic fistula Symptoms: None Medication:— Clinical Procedure: Appendectomy • wedge-shaped resection of rectum Specialty: Gastroenterology and Hepatology Objective: Unusual setting of medical care Background: Treatment methods for appendiceal-colonic fistulas differ greatly depending on whether lesions are benign or malignant. If the tumor is malignant, appendectomy with lymph node resection (ileocecal resection or right hemicolectomy) should be performed. There is no consensus on the method of surgery for organs infiltrated by appendiceal cancer. Furthermore, there are no reported laparoscopic cases that could be prevented from over-surgery by laparoscopy examination or rapid intraoperative pathological examination. Case Report: A 76-year-old man presented with positive fecal occult blood. Lower endoscopy revealed a 10-mm tumor in the rectosigmoid colon accompanied by white moss. A biopsy showed inflammatory granulation and no malignancy. Fluorodeoxyglucose-positron emission tomography showed highly increased accumulation at the tip of the appendix, and the standardized uptake value max was 7.3. We suspected a benign lesion rather than appendiceal cancer with infiltration into the rectosigmoid colon; therefore, we performed laparoscopic appendectomy and wedge-shaped resection of the rectum of the sigmoid colon. An intraoperative rapid pathological examination showed no appearance of malignancy; therefore, additional resection was omitted, and an ileostomy was created in the right lower quadrant. A permanent pathological examination showed complicated appendicitis, with no appearance of malignancy. The ileostomy was closed on postoperative day 25, and the patient was discharged on postoperative day 32. Conclusions: In cases where there is difficulty in identifying whether the appendiceal-colonic fistula lesion is benign or malignant, laparoscopy and intraoperative rapid pathological examination may be useful in avoiding excessive treatment.

Submerged aquatic vegetation (SAV) such as seagrass alters hydrodynamics as a drag force. Many studies have investigated the SAV drag force, but the time scales studied have been short (several days to a few weeks), ignoring seasonal variation, and the spatial scales have been small (several meters). Here, we performed field research and developed a new physical model incorporating seasonally varying SAV morphology (leaf length, leaf width, and shoot density) to investigate the effects of SAV drag force on the current field. We found that SAV attenuated the current velocity 50–70% during the 5-month computational period. Furthermore, the model showed a clear negative relationship between the leaf area index calculated from SAV morphology and current velocity. The physical model developed in this study can facilitate more accurate quantification of organic matter burial rates and the estimation of blue carbon sequestration by considering the SAV drag force.

症例は79歳，男性．平成19年2月上旬より発熱があり，その後悪寒戦慄，意識状態の低下があり近医を受診．CRPの上昇を認め，腹部CTにて肝左葉に低吸収域を認めたため肝膿瘍の診断に入院．入院後抗生剤投与と膿瘍ドレナージにて軽快．肝膿瘍の原因検索として胆道系に異常を認めず，大腸内視鏡でRsに全周性の2型病変を認め，生検にて高分化型腺癌であった．3月に当科入院．CTにて肝膿瘍は消失しており他に肝腫瘍の所見は認めず．直腸癌の診断にて高位前方切除を施行．病理所見は高分化型腺癌，ss，ly1，v0，n0，stageIIであった．術後経過は良好で術後17日目に退院．現在術後3年経過するが直腸癌，肝膿瘍の再燃は認めていない．本症例の様に胆道系異常の認めない原因不明の肝膿瘍では大腸癌合併などを想定した消化管精査が必要と思われた．

With a view toward furthering the development of artificial liver systems, we have been culturing hepatocytes in vitro. The object of this research was to investigate the ideal conditions of oxygen tension for the efficient functioning of hepatocytes. Viable hepatocytes isolated from rat livers were cultured under five different oxygen tensions: 5, 10, 20, 50 and 90% O2. DNA contents, gluconeogenesis, urea synthesis, adenosine triphosphate (ATP) levels, and lipid peroxidation of hepatocytes were evaluated. Under the 5% oxygen conditions, the function of hepatocytes was very inferior and was accompanied by a low ATP level. However, hepatocytes cultured under 90% oxygen tension functioned less effectively than the control (20% O2) with elevated lipid peroxidation. The data in this study suggest that the optimum oxygen condition for cultured hepatocytes is 10 approximately 50%, and that especially under conditions of 20% oxygen tension, i.e., that of the ordinary atmosphere, hepatocytes can function most effectively.

Since 1987, we have been developing a bioartificial liver (BAL) using multiplated cultured hepatocyte monolayers. With the goal of promoting hepatic functions of cultured hepatocyte monolayers, we combined the use of a collagen gel layer over the monolayers of hepatocytes and/or cocultured hepatocytes with nonparenchymal cells (NPCs). The study was divided into four groups according to culture configurations: Group 1: hepatocyte monolayer culture (control); Group 2: coculture of hepatocytes and NPCs; Group 3: hepatocyte monolayer with a overlaid collagen gel layer; and Group 4: coculture with a overlaid collagen gel layer. The culture continued for 14 days. Morphological changes and hepatic functions were evaluated by urea and albumin syntheses. The morphological status of the hepatocytes remained for 2 weeks in Groups 3 and 4. Deterioration and detachment of hepatocytes and/or NPCs started in Group 1 and 2 on the third day in culture. Significantly high urea synthesis was noted in Group 4 (p < 0.001 compared with Group 1 and 2: p = 0.0014 compared with Group 3). Although there was no significant difference in albumin synthesis among the four groups, those hepatocytes covered by the collagen gel (Groups 3 and 4) tended to secrete albumin throughout the observation period. These results indicted that the environment, although artificial (but close to the in vivo state), supplied with collagen gel and the coculture, enhanced the activities of the cultured hepatocyte monolayers. We suggest that use of cocultured hepatocytes under a collagen gel is a promising candidate for a bioreactor of multiplated BAL.

肝動注療法後のbiloma内にpseudoaneurysmが形成され原因不明の下血として発症した1例を経験した．症例は73歳，男性．上行結腸癌同時性多発肝転移にて回盲部切除術，胆嚢摘出術，肝動脈リザーバー留置術後に肝動注化学療法を施行した．5カ月後に肝内側区の梗塞と肝門部から肝S4にかけてのbilomaを認めた．CPT-11による全身化学療法に変更し約1年後に肝転移は消失したがbilomaに変化を認めなかった．その後下血をきたし入院した．入院から3度目のCTでbiloma内にpseudoaneurysmが認められ，MRIでbiloma内への出血と診断された．肝動脈塞栓術を施行し下血は軽快した．5カ月後，再度下血が出現．初回とは別の血管に形成されたpseudoaneurysmに塞栓術を施行した．出血源の確定にはCTを繰り返し撮影することが有用であり肝動注療法においてはbilomaの部位にpseudoaneurysmが繰り返し形成される可能性を念頭におくべきである．

膵管内乳頭粘液性腫瘍（IPMN）は粘液貯留による膵管拡張を特徴とする腫瘍で，過形成，腺腫の良性腫瘍から腺癌までを含む疾患群であり，通常型の膵癌と比べ予後が良好と言われているが，再発や多中心性発生の可能性がある．今回，われわれは膵管内乳頭粘液性腺癌（IPMC）にて膵体尾部切除後の残膵再発を切除し，さらに膵鉤部に発生した膵癌に対し残膵全摘術を施行した症例を経験した．症例は59歳男性で，1999年4月微小浸潤を伴うIPMCにて膵体尾部，脾切除術施行した．2002年11月に膵断端に嚢胞性腫瘍を認め，膵部分切除術施行した．組織所見はIPMC由来の浸潤癌と診断された．2004年7月膵鉤部に腫瘍を認め，残膵全摘術を施行した．組織所見は浸潤性低分化型腺癌であり，異時性膵癌合併が示唆された．IPMNは粘液の漏出による再発，多中心性発生，通常型膵癌の合併の可能性があり，慎重な経過観察が必要である．

A comprehensive coastal ecosystem model coupled with 3D hydrodynamic model with non-hydrostatic flow was developedto understand the processes of accumulation of anoxic water masses (and hydrogen sulfide) in borrow pits andtheir upwelling to shallow region. This model was applied to the borrow pit in Mikawa Bay and compared to the observeddata. To examine the effectiveness of the model, the numerical results were compared with those of a hydrostaticpressure model. The comparison proved the non-hydrostatic model to be much more adequate atsimulating the stratification structure and the vertical mixing in the pit. Moreover, it turned out that the non-hydrostaticmodel also reproduces reasonably the upwelling process under strong wind conditions.

An impact test equipment was developed. This equipment is able to produce comparatively low load rate of impact. The impact strength of the acrylic adhesive under low temperature was measured using the developed impact test equipment. By using aluminum alloy as adherend, the equipment can measure the impact strength of acrylic adhesive. The tensile strength of the adhesive under various load rate and low temperature were measured. Conventional equipments were also used for these tests. Relations between the load rate, the test temperature and the tensile strength of adhesive were investigated. As an experimental result, at any case of load rate the tensile strength of the acrylic adhesive increased once with temperature decrease. However, when the temperature decreased lower than a specific value, the strength of the adhesive decreased. The temperature that the strength of the adhesive becomes maximum rises with the increase of the load rate. The change of strength of the acrylic adhesive is influenced by the viscosity of the adhesive itself.

A three-dimensional (3D) hydrodynamic model is employed to investigate the mean flow pattern in the Arabian Gulf. After calibration of the model against measured data, simulations are done for summer and winter hydrological scenarios. As the dynamics of the Gulf are significantly influenced by salinity and temperature, measured values of these parameters are directly used to get a realistic flow field. Numerical experiments with the model are carried out such in a way that the importance of the major factors contributing to the residual current is investigated by using their suitable combination. The model results show that the density field develops different flow patterns in the summer and winter, except for a common feature of anticlockwise gyre in the northern Gulf. While the tide is found to contribute little to the flow, the wind generates strong currents along the coasts of Saudi Arabia and the United Arab Emirates.

Studying and understanding the hydrodynamic conditions of the Arabian Gulf have received growing interest over the last few decades. This is attributed to the strategic importance of the area, as it is used in transporting most of the oil produced from the Gulf countries in addition to being the main source of desalination water that such countries rely on heavily. Yet, only few comprehensive studies have been conducted to fully characterize and interpret the hydrodynamics of the Arabian Gulf. The current study is one of those efforts directed towards the understanding of water dynamics in the Arabian Gulf. This has been achieved by virtue of three-dimensional numerical modeling supported by field measurements conducted recently in the southern shelf to verify the output results. The southern shelf refers to the southern region of the Arabian Gulf, bounded from the west by the Qatar Peninsula and from the south by the United Arab Emirates. The utilized numerical model employs a rectilinear grid system with parallel layers and uses explicit technique in solving the continuity, momentum, and heat/solar-transferee governing equations. The model employs typical seasonal wind fields developed via combining Hellerman historical data averaged over the last 30 years with other data recorded recently in the southern shelf. Salinity and temperature fields are also incorporated in the simulation model, considering the Mt. Mitchell National Oceanic and Atmospheric Administration data complemented with field measurements in the southern shelf. The conducted field measurements include tidal records at three stations and current measurements at one station and are found to reasonably agree with the simulated results.

An impact test equipment was developed to measure the strength of adhesive resins subjected to impact loads at low temperatures. The stress wave propagating the adhesive layer and the adherend was analyzed by the one-dimensional elastic wave theory. It was confirmed that the average stress value in the adhesive layer could be evaluated by the stress value of the adherend. Therefore, the measurement method with this equipment is effective. The impact strength of an acrylic adhesive was evaluated using the developed test equipment. As a result of the impact test, the impact strength of the acrylic adhesive increased once with temperature decrease. However, when the temperature decreased lower than a specific value, the impact strength decreased. It was considered that this phenomenon occurs because the adhesive becomes brittle as the temperature decrease.

We have developed a new assembly method of metal enclosures in which the combined use of acrylic adhesives and rivets (fasteners) are adopted as an alternative to arc welding. We have achieved the following effects: (1) elimination of skill working such as welding operation and strain correction, (2) improvement of working environment by the elimination of welding operation and putty work, (3) simplification of manufacturing process and cost reduction by introducing heatless bonding method (adhesive bonding), (4) compatibility of rigidity with weight reduction of products, (5) total energy consumption decrease to 78% by adopting this new assembly method, to 64% by thinner galvanized steel and to 51% by pre-coated steel.

Aiming at providing numerical tools useful to assess the impacts of coastal development pressures on marine life, a Lagrangian model for population dynamics of pelagic eggs and larvae of the greasyback shrimp, Metapenaeus ensis, in Osaka Bay was developed and improved based on laboratory experiments. The model was combined with a 3-D Eulerian numerical model that predicts physical and biological conditions of the habitat. A series of numerical experiments was done to investigate their transport processes from the spawning grounds, and the concentration process of full-grown larvae towards the mouth of Yodo River that flows into the innermost basin. Model results revealed, as a general tendency, that the early larval developmental stages through nauplius to zoea continue to drift like a passive tracer, and begin to concentrate at the river mouth area after the mysis stage, mainly avoiding low saline environment in the surface layer. This suggests that the full-grown larvae may be favored with chance to take advantage of the river-induced gravitational circulation that dominates the innermost estuarine basin. In addition, it was found that tidal condition around the spawning period also exerts a considerable influence upon the fate of pelagic larvae.

In deep drilling, a series of our study is going ahead with the plan for improvement of accuracy. As the result, the control system for axial deviation of holes was developed. This paper deals with a new measuring method for axial deviation of holes, which was useful not only measurements of machined parts but also in-process sensing. The deviation can be evaluated from the path length and the pulse amplitude of the ultrasonic flaw detector in this new measuring system. In comparison with the optical measuring system using laser and coner cube prism, this tool can be simply constructed, because was not in need of a measuring pipe in tool shank and a prism holder in tool head. For this result, tool head of small diameter can be produced. In conclusion, the guide for practical use was presented on the control system for axial deviation of holes.

The mechanism of water pollution in Lake Hamana, one of the typical highly eutrophicated semi-enclosed estuaries in Japan, has been studied using a numerical 3D physical–biochemical coupling model. In this study, the chemical oxygen demand (COD) was adopted as an index of the lake water quality, and the spatial pattern of the average COD concentration during the summer from 1988 to 1991 was simulated by the model. It was suggested from the numerical result that the water quality in Lake Hamana was essentially influenced by the phytoplankton production, although the dissolved organic matter accounted for the major fraction of COD constituent in the lake. The evaluation of the biological processes over the whole lake region showed that the autochthonous COD flux associated with the primary production may be almost 10 times larger than the external loading flux. Because the phosphate turned out the most limiting nutrient to the phytoplankton production and most of the phosphorus pool in the water column appeared to be supplied from the sediment, it was considered that the benthic phosphorus flux would be the most critical factor to the autochthonous COD in the lake.

Axial deviation of holes is a serious problem in deep drilling operation. As the results, the control system for axial deviation of holes in deep drilling was developed. The guide-pad on the new drilling tool head, the control pad, slightly moves up and down by piezo actuator in radial direction with each tool revolution. The axial deviation of the tool head is measured by in-process sensing system with laser and corner cub prism. This paper presents the development of the control method of pad using piezo actuator and the axial deviation mechanism by control pad is clarified. And it is verified various factors for deviation ability.

To assess the possibility of using hepatocytes from ischemic liver, as a bioreactor of a hybrid artificial liver, we investigated the influence of warm ischemia on the isolation and culture of hepatocytes in rats. Warm ischemia was induced by clamping the liver hilus and the animals were divided into 3 groups according to the duration of ischemia: group A (no ischemia), group B (10 minutes) and group C (20 minutes). Hepatocytes were isolated by the collagenase perfusion method and cultured for 5 days. The yield and viability of the isolated hepatocytes were lower in group C. Rate of attachment was decreased as the duration of ischemia increased. There was no significant difference observed in functions in culture. Sufficient hepatocytes, as a bioreactor, can be isolated and cultured from warm ischemic liver within 10 minutes. Though the number of available hepatocytes were diminished, hepatocytes procured from longer warm ischemic liver could be utilized as a bioreactor.

手術時切除肝を用いてヒト肝細胞の分離培養を行い,単離肝細胞の収量,viability,培養肝細胞機能が入手肝組織の温阻血時間といかなる関係にあるかを検討した.肝細胞の分散はコラゲナーゼとディスパーゼの混合液を灌流することにより行い,分散された肝細胞を10日間培養し,糖新生能,尿素合成能,DNA量を測定した.入手肝組織の温阻血時間は,0-300分であった.その結果,単離肝細胞のviabilityは肝温阻血時間と関係がなく87.9%であったが,収量との間には有意の相関関係を認めた(p

Cultured porcine hepatocytes with reasonable metabolic functions are a promising bioreactor for a hybrid artificial liver in the treatment of liver failure. A cytotoxic human serum (t-serum) against cultured porcine hepatocytes was accidentally discovered during preliminary experiments, however, which prompted the authors to study the mechanism of the cytotoxicity and the frequency of occurrence of the cytotoxic sera. Among 103 individual sera examined, seven (6.8%) sera showed cytotoxicity to cultured porcine hepatocytes. T-serum heated at 56 degrees C for 30 min completely lost its cytotoxic activity, but the inactivated cytotoxicity was restored by the addition of rabbit complement to the inactivated t-serum. IgM-depleted t-serum produced by 2-mercaptoethanol treatment abolished the cytotoxicity to porcine hepatocytes. The cytotoxic reactions were therefore thought to be mediated by IgM capable of complement activation. Although IgM binding to porcine hepatocytes was also seen in nontoxic sera, the IgM did not activate complement. This implies differences in hepatocyte surface antigens recognized by IgM from t- and nontoxic sera. Before clinical application of a hybrid artificial liver using cultured porcine hepatocytes, detection of cytotoxic human IgM against porcine hepatocytes is necessary, and the means of eliminating the cytotoxic IgM from the hybrid artificial liver system, or of inactivating complement in the system, will be desirable in cases positive for cytotoxic IgM.

A 71-year-old man suffering from epigastric discomfort and dizziness was admitted to our hospital and diagnosed with advanced gastric cancer with bulky lymph node metastases and liver metastasis. We thought a complete resection would be difficult, so he was treated with neo-adjuvant immunochemotherapy in combination with S-1 80 mg/m2 (2 weeks administration and 2-week rest), paclitaxel (PTX) 50 mg/m2 (day 1, 8, 15) and Lentinan (LNT) 2 mg/body (day 1, 8, 15). After 5 courses of this treatment, swollen lymph nodes decreased in size and the metastatic liver tumor disappeared. Total gastrectomy with lymph node dissection was performed. The histological diagnosis was pT2 pN0, Stage I B. Histological effects of primary tumor and lymphnodes were judged to be grade 2 and grade 3, respectively. We considered that the combination of S-1, PTX and LNT can be effective and safe for advanced gastric cancer.

A non-contact surface resistivity probe for materials with resistivity greater than 109 Ω has been developed using surface potential measurement combined with corona charging. The probe is composed of a grid type corona charger and a surface voltmeter located next to the charger. A test material was placed below the probe without contact to the material at a gap of 2 mm. The time variation of the surface potential and the saturation surface potential beneath the charged area are theoretically a function of the surface resistivity; therefore, measurement of the rise time and the saturation potential can be used to predict the surface resistivity in the ranges of lower and higher surface resistivity, respectively. The calibration equation for the probe was determined by solving the circuit equation for a one-dimensional simple circuit model and by extension of the simple model to the actual probe arrangement using experimentally derived constants. The lower surface resistivity, ρsal (from 109 to 8×1013 Ω), can be predicted from ρs = 1.0×1011×Tm1.64 using a 63% rise time, Tm. The higher surface resistivity, ρsah (from 8×1013 to 1016 Ω), can be predicted using the equation ρs = 3.0×1014×Vm1.70 with the converted surface potential, Vm.

We have been developing a multiplate type of bioartificial liver (BAL) using primary cultured hepatocyte monolayers since 1987. This BAL has been shown to prolong the survival time of anhepatic dogs and rabbits. Initially, hepatocytes were cultivated on collagen-coated plates. To increase the multiplated BAL function, a sandwich cultivation method was employed in which rat hepatocytes were cultured between two collagen gel layers and were then evaluated in both stationary and perfusion cultures. In the stationary culture, the sandwich method showed a higher activity in urea synthesis than in the other culture methods (culture on a collagen coating, culture on a collagen gel, and culture between a collagen coating and a collagen gel) for 14 days. In the perfusion culture, a BAL housing cultured hepatocytes (6.5 x 10(7) cells) in the sandwich system showed urea synthesis activity ranging from 17.5 to 22.6 micrograms/2 x 10(6) cells/90 min. This activity was maintained for 5 days in the perfusion culture. The sandwich type of cultivation is applicable to the multiplated BAL.