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Biomedical subjects

K Funatsu

Publications and source records attributed to K Funatsu.

At least 19 recordsLinked to original sources
PubMed2001

Hybrid artificial liver using hepatocyte organoid culture.

We developed 2 types of hybrid artificial liver modules using hepatocyte organoid culture. One was a polyurethane foam (PUF)/hepatocyte spheroid packed-bed module. Hepatocytes spontaneously formed spheroids in the PUF pores, and they maintained liver-specific functions well for at least 2 weeks in vitro. As a preclinical experiment, a hybrid artificial liver with 200 g porcine hepatocytes was applied to a pig (25 kg) with liver failure and showed that the hybrid artificial liver was effective in support of liver functions and stabilization of general conditions. We established a new technique of hepatocyte organoid formation using centrifugal force. A hepatocyte organoid formed by centrifugation in hollow fibers maintained functions for more than 4 months in vitro. We developed a new sinusoid-like structure module having hollow fibers arranged by spacers in a micro-regular arrangement. Inoculated hepatocytes in the extra-fiber space of the module formed the organoid by centrifugation, and they maintained the functions for at least 1 month in vitro. The results indicated that this module seems to be promising as a hybrid artificial liver.

Animals↗
PubMed2001

The efficacy of nafamostat mesilate on the performance of a hybrid-artificial liver using a polyurethane foam/porcine hepatocyte spheroid culture system in human plasma.

Nafamostat mesilate (FUT) is a protease inhibitor of complement activation. The present study investigates whether FUT protects porcine hepatocytes from being injured by human plasma in a multi-capillary polyurethane foam packed-bed culture system (MC-PUF) such as the hybrid-artificial liver (PUF-HAL). Human plasmas with 1 mM of added ammonia were perfused using a small-scale PUF-HAL with porcine hepatocytes. FUT was continuously infused (10 microg/ml, 50 microg/ml). The ammonia detoxification was maintained in human plasma for 24 hours and for 48 hours with FUT which suppressed the rapid increase of asparaginic acid aminotransferase (AST) and alanine aminotransferase (ALT). After 60 hours of perfusion, hepatocyte spheroids completely collapsed in the human plasma, but a small amount of hepatocyte spheroid was maintained by FUT. The effect of FUT was slightly greater at 50 microg/ml than at 10 microg/ml. Our results suggest that FUT has protective effects against porcine hepatocytes in human plasma, and our PUF-HAL using porcine hepatocytes can function in human plasma for about 48 hours with FUT.

Alanine Transaminase↗
PubMed2001

[Basic study about the development of the hybrid-artificial liver support system using human hepatoma cell lines (Hep G2, Huh 7): effects on liver functions by extracellular matrix (type I collagen) in monolayer culture].

The risk of xenozoonosis infections poses the greatest obstacles against the clinical application of hybrid-artificial liver support system (HALSS). To resolve this issue, we used human hepatoma cell lines (Hep G2, Huh 7) in a type I collagen-coated monolayer culture system, and analyzed liver specific functions such as ammonia removal and albumin synthesis capacity. Ammonia removal activity (nmol/10(6) nuclei/hour) and albumin synthesis activity (microgram/10(6) nuclei/day) were upregulated in both Hep G2 and Huh 7 by type I collagen-coated monolayer culture. In particular, Hep G2 cultured in type I collagen-coated monolayer demonstrated relatively high ammonia removal and albumin synthesis capacity. These results indicate the possibility of the application of human hepatocytes to HALSS.

Albumins↗
PubMed2000

Novel canonical coding method for representation of three-dimensional structures

A new canonical coding method for representation of three-dimensional structures, CAST (CAnonical representation of STereochemistry), is described. CAST canonically codes stereochemistry around an atom in a molecule. The same CAST notations are given for atoms of molecules in the same conformation. The CAST code is based on the dihedral angles of four atoms that are uniquely defined by a molecular tree structure. CAST has successfully represented similarities and differences between several conformers.

Journal Article↗
PubMed2000

Partial least squares modeling and genetic algorithm optimization in quantitative structure-activity relationships.

Quantitative structure-activity relationship (QSAR) studies based on chemometric techniques are reviewed. Partial least squares (PLS) is introduced as a novel robust method to replace classical methods such as multiple linear regression (MLR). Advantages of PLS compared to MLR are illustrated with typical applications. Genetic algorithm (GA) is a novel optimization technique which can be used as a search engine in variable selection. A novel hybrid approach comprising GA and PLS for variable selection developed in our group (GAPLS) is described. The more advanced method for comparative molecular field analysis (CoMFA) modeling called GA-based region selection (GARGS) is described as well. Applications of GAPLS and GARGS to QSAR and 3D-QSAR problems are shown with some representative examples. GA can be hybridized with nonlinear modeling methods such as artificial neural networks (ANN) for providing useful tools in chemometric and QSAR.

Algorithms↗
PubMed2000

Intensive promotion of spheroid formation by soluble factors in a hepatocyte-conditioned medium.

We developed a hybrid artificial liver and a drug metabolism simulator using polyurethane foam (PUF) in which primary hepatocytes spontaneously form functional spheroids. Gel filtration liquid chromatography analysis of a hepatocyte-conditioned medium during spheroid formation showed that some substances secreted by primary rat hepatocytes accumulated advantageously inside the pores of PUF compared with outside. Similar substances were detected in a hepatocyte-conditioned medium from a positively-charged surface by concentrating the substances using an ultrafiltration membrane of a molecular weight-cutoff of 50 kD. These substances were shown to act as soluble factors on freshly isolated primary rat hepatocytes to promote spontaneous and rapid spheroid formation, depending on their concentration by preventing them from initially attaching and spreading on a positively-charged surface. In particular, using 50-fold concentrated substances, about 80% of total hepatocytes formed the floating spheroids within 72 h of culture. The resulting spheroids had a diameter distribution mainly ranging from 40 to 70 microm and expressed high-level liver-specific functions compared with a conventional monolayer.

Ammonia↗
PubMed2000

Development of a hybrid artificial liver using a polyurethane foam/hepatocyte-spheroid packed-bed module.

Primary dog hepatocytes spontaneously formed spheroids in the pores of polyurethane foam (PUF) within 1-2 days of stationary culture. The spheroids, about 100-150 microm in diameter, partly attached to the surface and immobilized inside these pores. The lidocaine disappearance rate decreased to about 4 microg/10(5) viable cells/day for 10 days, while in the PUF/spheroid culture the rate was maintained at almost the initial level of 8 microg/10(5) viable cells/day for 10 days. Then, two scales of PUF packed-bed modules were designed. A small module (PUF volume; 14.5 cm3) was used for in vitro culture to investigate optimum culture conditions, and a large module (PUF volume; 300 cm3) was designed for dog experiments. Hepatocytes inoculated in these modules also formed spheroids and maintained almost the same activity of albumin secretion rate (111 microg/cm3 PUF/day in the small module and 87.7 microg/cm3 PUF/day in the large module). These results indicate that the PUF packed-bed module containing hepatocyte-spheroids is promising as a hybrid artificial liver.

Albumins↗
PubMed2000

Conditions required for a hybrid artificial liver support system using a PUF/hepatocyte-spheroid packed-bed module and it's use in dogs with liver failure.

We studied the effects of a hybrid artificial liver support system we developed on dogs with hepatic failure. The system consisted of a multi-channel polyurethane foam packed-bed culture module, including primary dog hepatocyte spheroids. Blood ammonia was well metabolized by 20 g hepatocytes, but the other functions such as glucose concentration, total bile acid concentration, and survival time required 30 g hepatocytes to improve conditions. We found that we should use a culture substratum that easily forms spheroids, and that an artificial liver module should be used as soon as possible after spheroid formation by hepatocytes in the module.

Animals↗
PubMed1999

Evaluation of a hybrid artificial liver using a polyurethane foam packed-Bed culture system in dogs.

BACKGROUND AND AIMS: We developed a polyurethane foam packed-bed culture system of hepatocyte spheroids as a hybrid artificial liver (PUF-HAL), which was effective for recovery from liver failure in rat experiments. In this report, the design of a scaled-up PUF-HAL for dogs is described and evaluated using a dog acute liver failure model. METHODS: Warm ischemic liver failure was induced with a portocaval shunt in each dog. The dogs were divided into two groups: (1) a control group (N = 4), in which each dog was attached to a PUF-HAL without hepatocytes for 9 h, and (2) a HAL group (N = 5), in which each dog was attached to a PUF-HAL with hepatocytes. Blood pressure, blood ammonia, blood glucose, serum creatinine, and other parameters related to liver function were compared between the two groups. RESULTS: In the HAL group, blood ammonia and serum creatinine levels were significantly lower, and blood pressure and blood glucose levels significantly higher, than those in the control group. CONCLUSIONS: The scaled-up PUF-HAL developed for large animals is useful as a liver support system in the dog acute liver failure model.

Ammonia↗
PubMed1998

Formation of a spherical multicellular aggregate (spheroid) of animal cells in the pores of polyurethane foam as a cell culture substratum and its application to a hybrid artificial liver.

Monkey kidney cells (Vero), human embryonic kidney cells (293), human liver cells (PLC/PRF/5), and primary rat, dog, and porcine hepatocytes formed spherical multicellular aggregates (spheroids) in the pores of polyurethane foam which was used as a cell culture substratum. These spheroids of various cell types express high cell activity for a long period. A practical hybrid artificial live support system composed of a multi-capillary polyurethane foam packed-bed type cell culture module including primary hepatocyte spheroids was developed. The success of the system is indicated by an 80% recovery rate in hepatic failure rats which died in control experiments.

Animals↗
PubMed1997

[CDw90 (Thy-1) expression on CD34 positive cells in peripheral blood stem cell harvest].

In this study, we investigated CDw90 (Thy-1) expression in CD34+ cells and hematopoietic colony-forming ability in purified CD34+ Thy-1+ and CD34+ Thy-1 fractions in the peripheral blood at the PBSCH. The high proliferative potential colony-forming cells (HPP-CFC), which are considered to be more primitive hematopoietic stem cells, were found more frequently in the purified CD34+ Thy-1+ fraction than in the purified CD34+ Thy-1- fraction. Thus, it is useful to decide the optimal time of PBSCH to measure the CD34+ Thy-1+ cells as well as CD34+ cells in the peripheral blood by flow-cytometry. In CD34+ acute myeloblastic leukemia (AML) cells, the co-expression rate of CD34 and Thy-1 was negative, suggesting that it may be possible to estimate the contamination of CD34+ AML cells by the Thy-1 expression rate in CD34+ cells at PBSCH.

Antigens, CD34↗
PubMed1994

Tissue plasminogen activator (t-PA) production by a high density culture of weakly adherent human embryonic kidney cells using a polyurethane-foam packed-bed culture system.

Weakly adherent cells of the 293 line attached well to the internal surface of polyurethane foam (PUF) and grew to the high density of 6.83 x 10(7) cells/cm3 PUF in stationary culture. The maximum productivity of tissue plasminogen activator (t-PA) was 0.158 IU/10(6) cells per day. The productivity decreased at the stationary phase of cell growth, so we designed a PUF-plate packed-bed culture system for high density culture and continuous production of t-PA. A maximal cell density of 3.24 x 10(7) cells/cm3 PUF and a t-PA productivity of 0.326 IU/10(6) cells per day were obtained in 25-day perfusion cultures. Although the cell density decreased to half that in PUF stationary culture, the t-PA productivity increased twofold and was maintained for 25 culture days.

Cell Division↗
PubMed1994

A case of a primary hepatic tumor causing segmental changes on imaging and its relation to Zahn's infarct.

A 69-year-old female was admitted to our hospital for further examination of an intrahepatic mass which had been found while undergoing a complete physical examination. The mass measured 4 cm in size and was located in the medial segment (S4) of the liver. On computed tomography (CT), S4 was observed to be 'atrophied' and was well enhanced segmentally. A celiac angiogram showed segmental staining, and a transarterial portogram demonstrated portal stoppage of S4 from the left branch. However, no segmental intensity difference was seen on magnetic resonance imaging (MRI). An aspiration biopsy showed adenocarcinoma and thus an operation was performed under a tentative diagnosis of intrahepatic cholangiocarcinoma. The postoperative diagnosis of the tumor was combined hepatocellular and cholangiocellular carcinoma. However, no histological abnormality was seen in S4, contrary to the expectation of Zahn's infarct. In this study, we discuss the mechanism and imaging findings of Zahn's infarct, the possible reasons as to why no pathological change was seen in S4, as well as stress the rarity of reports on Zahn's infarct in cases of portal thrombus due to hepatocellular carcinoma.

Aged↗
PubMed1992

Adenine nucleotide content of thymoma-derived lymphocytes.

Purine and pyrimidine metabolites are essential substances for cells. We have measured the adenine nucleotide (AN) contents of thymocytes from 15 human thymomas, 11 adjacent non-neoplastic thymuses and 3 children's thymuses. There was no significant difference in AN content of thymocytes between thymoma and children's thymus. But, AN content of adjacent non-neoplastic thymuses was significantly lower than that of thymoma or children's thymus. In mixed type thymoma, ATP content in thymocytes was significantly higher than that in lymphocytic type thymoma. These data indicate that thymocytes in thymoma may show further T cell maturation probably associated with the functional microenvironment of the neoplastic epithelial cells just like the children's thymus.

Adenine Nucleotides↗
PubMed1991

High density culture of anchorage-dependent animal cells by polyurethane foam packed-bed culture systems.

Monkey kidney cells (Vero) and Chinese hamster ovary cells (CHO-K1) attached to the internal surface of polyurethane foam (PUF) and grew to a high cell density (1.1 x 10(8) cells/cm3 PUF and 4.2 x 10(7) cells/cm3 PUF, respectively) in a PUF-plates packed-bed culture system. This density of Vero cells was twice that obtained previously with a PUF-particles packed-bed culture system. A maximum cell density of 6.7 x 10(7) cells/cm3 culture vessel volume was obtained in a PUF-disc packed-bed culture of Vero cells. From the cell density of CHO-K1, growing in a monolayer on the surface of PUF and a petri dish, per bulk volume of PUF, we estimated that a surface area to volume ratio of PUF plates effective for cell growth was about 109 cm2/cm3.

Animals↗
PubMed1991

High albumin production by multicellular spheroids of adult rat hepatocytes formed in the pores of polyurethane foam.

Adult rat hepatocytes formed spherical multicellular aggregates (spheroids) when they were cultured in the pores of polyurethane foam (PUF). The diameter of the spheroids was within the range 100-200 microns. These spheroids partly attached and immobilized in the PUF pores for at least 2 weeks. The albumin production rate by the spheroids increased up to 17.0 micrograms/10(6) nuclei per day during the first 6 days and maintained at a high level for 2 weeks. In contrast, the albumin production rate by the monolayer markedly decreased after 3 days. The spheroid culture using PUF seems to be a convenient and simple method for maintaining some differentiated functions of hepatocytes and for making a bioreactor using the function of spheroids.

Albumins↗
PubMed1990

Anchorage-dependent mammalian cell culture using polyurethane foam as a new substratum for cell attachment.

Anchorage-dependent mammalian cells were cultivated at high cell density in a novel culture system using polyurethane foam (PUF) as a substratum for cell attachment. PUF has a macroporous structure giving a high surface area to volume ratio. Monkey kidney cells (Vero) and Chinese hamster ovary cells (CHO-K1) attached to the internal surface of PUF and grew to a high cell density (1.04 X 10(8) cells/cm3 PUF and 3.5 X 10(7) cells/cm3 PUF, respectively) in PUF stationary cultures. In addition, we have designed a PUF-particle packed-bed culture system for high density mass cell culture. A maximum cell density of 2.4 X 10(7) cells/cm3 culture vessel volume was obtained in a packed-bed culture of Vero cells.

Animals↗