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Biomedical subjects

T Akaike

Publications and source records attributed to T Akaike.

At least 55 records · Page 3Linked to original sources
PubMed2001

Hepatocyte attachment onto thermosensitive poly(N-isopropylacrylamide-co-N-p-vinylbenzyl-O-beta-D-galactopyranosyl-(1 --> 4)-D-gluconamide).

Temperature sensitive poly(N-isopropylacrylamide) (PIPAAM) was incorporated into hepatocyte-recognizable poly[N-p-vinylbenzyl-O-beta-D-galactopyranosyl-(1 --> 4)-D-gluconamide] (PVLA) for thermal modulating of hepatocyte attachment. The copolymer, poly(N-isopropylacrylamide-co-N-p-vinylbenzyl-O-beta-D-galactopyranosyl-(1 --> 4)-D-gluconamide) (abbreviated as [P(IPAAM-co-VLA)] (PIPAAM/PVLA = 9/1 in mol%) exhibited lower critical solution temperature (LCST) at 34 degrees C and also showed very good hepatocytes-recognizablility through the specific interaction between asialoglycoprotein receptors on the cell surfaces and galactose moiety of the copolymer. The cells attached on this copolymer were easily detached by lowering the temperature below the LCST of the copolymer. Morphological damage of the detached cell was not observed.

Acrylic Resins↗
PubMed2001

Incorporation of sulfonylurea into sugar-carrying polymers and their effects on insulin secretion from MIN6 cells in a solution state.

A hypoglycemic sulfonylurea (SU) was incorporated into non-reducing glucose-bearing polystyrene (PS) derivative for enhanced interaction with, and insulin secretion from an insulinoma cell line (MIN6). SU derivative was copolymerized with styrene having sugar moiety such as maltose or lactose. About an 80% increase in insulin secretion for poly(N-p-vinylbenzyl-D-maltonamide-co-SU) (p(VMA-co-SU)) was observed when the copolymer was added to the culture medium (SU: 25 mol%). whereas about 50% increase for poly(N-p-vinylbenzyl-D-lactonamide-co-SU) (p(VLA-co-SU)) was observed when compared with unstimulated cells. From the measurement of flow cytometry, the fluorescence intensity of MIN6 cells incubated in culture media containing FITC-labeled SU-incorporated copolymer increased remarkly owing to specific interaction between receptors in the cell membrane and SU ligands in the copolymer. When sugar and/or SU-incorporated copolymer were co-entrapped with the cells in agarose or collagen gel as an extracellular matrix for three-dimensional culture. p(VMA-co-SU) enhanced more insulin secretion from MIN6 cells than other polymers and it was found that collagen gel was more effective in insulin secretion than agarose

Animals↗
PubMed2001

Conjugation of Arg-Gly-Asp (RGD) sequence in copolymer bearing sugar moiety for insulinoma cell line (MIN6) culture.

Copolymers composed of an Arg-Gly-Asp (RGD) sequence for the adhesion molecule and sugar moieties were synthesized for an insulinoma cell (MIN6) culture. MIN6 cells attached on the poly(N-p-vinylbenzyl-D-maltonamide-co-6-(p-vinylbenzamido)-hexanoic acid-g-GRGDS) (p(VMA-co-VBGRGDS))-coated dishes were in a more aggregated form than other polymer-coated surfaces. P(VMA-co-VBGRGDS) also shows faster proliferation of MIN6 cells (about 18% higher) than with p(VLA-co-VBGRGDS). By interaction between cell and matrix, about 80% greater insulin secretion from MIN6 cells was produced with the p(VMA-co-VBGRGDS), and about 50% greater insulin secretion was produced with the poly(N-p-vinylbenzyl-D-lactonamide-co-6-(p-vinylbenzamido)-hexanoic acid-g-GRGDS) (p(VLA-co-VBGRGDS) as compared with unstimulated cells. Moreover, attachment of MIN6 cells treated with RGD monomer was suppressed approximately 50% for the p(VMA-co-VBGRGDS) surface. This result supported the idea that conjugation of adhesion molecules of RGD peptide in p(VMA-co-VBGRGDS) copolymer specifically interact with integrin families on MIN6 cell membrane.

Carbohydrate Sequence↗
PubMed2001

Incorporation of sulfonylurea into N-isopropylacrylamide as an extracellular matrix for an artificial pancreas.

High-molecular-weight N-isopropylacrylamide copolymers with small amounts of sulfonylurea (SU, typically 2-4 mol% in the feed) were synthesized by free radical polymerization in benzene. SU-incorporated polymer solutions (5, 6, 8, and 10% w/v) in a culture medium (pH 7.4, 0.15 M ionic strength) with islet cells were mixed and poured into Millicells which supported gel formation. In order to increase the gelation temperature, the SU-incorporated copolymer gel, p(NiPAAm-co-SU), was blended with the p(NiPAAm-co-AAc) polymer at a ratio of 4 to 96. Interaction between the islet cells and the synthetic matrix of SU-incorporated copolymer gel resulted in effective cell viability and such cell functions as insulin secretion. To verify the specific interaction between the SU (K+ channel closer)-incorporated copolymer and islet cells, the cells were pretreated with diazoxide, an agonist of the ATP-sensitive K+ channel (K+ channel opener), before interaction between the polymer and islet cells. This treatment suppressed the action of SU on the islet cells. The results from this study provide evidence that the SU-incorporated copolymer stimulated insulin secretion by specific interaction between SU moieties in the polymer and the islet cells.

Acrylamides↗
PubMed2001

[Hydrothorax during diagnostic laparoscopy].

An 83-yr-old, 44-kg woman with a 2-month history of abdominal distension received diagnostic laparoscopy. Except for chronic treated hypertension, she was healthy. The preoperative chest X-ray demonstrated small pleural effusion occupying the lower left hemithorax, but she did not present with dyspnea or chest pain. After premedication with intravenous ranitidine 50 mg, anesthesia was induced with thiopental 150 mg, vecuronium 7 mg and maintained by 1-2% sevoflurane in 50% N2O/O2. SpO2 decreased after insufflation of CO2, but breath sound was audible on both lungs. At completion of operation, chest X-ray revealed the left hemilateral hydrothorax and 650 ml of pleural fluid was suctioned. Blood gas improved and the tracheal tube was removed. The diagnosis of tuberculous peritonitis was established by the demonstration of granulomas of the peritoneum. We speculated on four reasons for the increased pleural effusion on the left thorax: 1) Increase of systemic and capillary pressure caused by CO2 insufflation. 2) Increase of capillary permeability by tuberculous pleuritis. 3) Decrease of colloid osmotic pressure by hypoalbuminemia. 4) Decreased pleural fluid removal because of venous compression caused by increased intrathoracic pressure. Peritoneal insufflation of CO2 to create the pneumoperitoneum may induce hydrothorax in patients with tuberculous pleuritis.

Aged↗
PubMed2001

[An automated electronic anesthesia record and automated urine output measurement].

We can now collect many parameters (NIBP, HR, ABP, SpO2, EtCO2, CCO, etc) from an anesthesia monitor in an automated electronic anesthesia record system. The function of automated urine output measurement has been added to an automated electronic anesthesia record system. A digital weight meter connected with a personal computer by RS-232 C is used to measure the weight of urine. We convert the weight to the volume hypothesizing that the density of urine is 1 g.ml-1. Physiologic parameters are recorded every 10 seconds from an anesthesia monitor and we can set the period of automated urine output measurement we like. We must enter the initial and final urine output but the intraoperative urine output is collected automatically to an automated electronic anesthesia record and visualized in urine bar graph. The total volume of urine is calculated. Computerized urine output measurement can record data more frequently, for example, every 10 minute. At the end of the operation, intraoperative data are sent to a host computer and the anesthesia record is printed. Combining the automated urine output measurement with an automated electronic anesthesia record system is useful in anesthesia practice of a long operation.

Anesthesia↗
PubMed2000

Tyrosine nitration by peroxynitrite formed from nitric oxide and superoxide generated by xanthine oxidase.

Peroxynitrite (ONOO(-)) is a potent nitrating and oxidizing agent that is formed by a rapid reaction of nitric oxide (NO) with superoxide anion (O(2)). It appears to be involved in the pathophysiology of many inflammatory and neurodegenerative diseases. It has recently been reported (Pfeiffer, S., and Mayer, B. (1998) J. Biol. Chem. 273, 27280-27285) that ONOO(-) generated at neutral pH from NO and O(2) (NO/O(2)) was substantially less efficient than preformed ONOO(-) at nitrating tyrosine. Here we re-evaluated tyrosine nitration by NO/O(2) with a shorter incubation period and a more sensitive electrochemical detection system. Appreciable amounts of nitrotyrosine were produced by ONOO(-) formed in situ (2.9 micrometer for 5 min; 10 nm/s) by NO/O(2) flux obtained from propylamine NONOate (CH(3)N[N(O)NO](-) (CH(2))(3)NH(2)(+)CH(3)) and xanthine oxidase using pterin as a substrate in phosphate buffer (pH 7.0) containing 0.1 mm l-tyrosine. The yield of nitrotyrosine by this NO/O(2) flux was approximately 70% of that produced by the same flux of preformed ONOO(-) (2.9 micrometer/5 min). When hypoxanthine was used as a substrate, tyrosine nitration by NO/O(2) was largely eliminated because of the inhibitory effect of uric acid produced during the oxidation of hypoxanthine. Tyrosine nitration caused by NO/O(2) was inhibited by the ONOO(-) scavenger ebselen and was enhanced 2-fold by NaHCO(3), as would be expected, because CO(2) promotes tyrosine nitration. The profile of nitrotyrosine and dityrosine formation produced by NO/O(2) flux (2.9 micrometer/5 min) was consistent with that produced by preformed ONOO(-). Tyrosine nitration predominated compared with dityrosine formation caused by a low nanomolar flux of ONOO(-) at physiological concentrations of free tyrosine (<0.5 mm). In conclusion, our results show that NO generated with O(2) nitrates tyrosine with a reactivity and efficacy similar to those of chemically synthesized ONOO(-), indicating that ONOO(-) can be a significant source of tyrosine nitration in physiological and pathological events in vivo.

Humans↗
PubMed2000

Galactosylated chitosan-graft-dextran as hepatocyte-targeting DNA carrier.

Lactobionic acid bearing galactose group was coupled with chitosan for liver specificity, and dextran was grafted to galactosylated chitosan (GC) for stability in water. Compared to the GC/DNA complex, the stability of the galactosylated chitosan-graft-dextran (GCD)/DNA complex could be enhanced. The particle size of the GCD/DNA complexes decreased as the charge ratio of GCD to DNA increased. Conformational change of DNA did not occur after complex formation with GCD compared with the conformation of DNA itself. The GCD/DNA complexes were only transfected into Chang liver cells and that of Hep G2 having asialoglycoprotein receptors (ASGR), indicative of specific interaction of ASGRs on cells and galactose ligands on chitosan.

Asialoglycoprotein Receptor↗
PubMed2000

Synergistic induction of apoptosis in murine hepatoma Hepa1-6 cells by IFN-gamma and TNF-alpha.

In this study, we examined the susceptibility of murine hepatoma Hepa1-6 cells to undergo IFN-gamma- and/or TNF-alpha-induced apoptosis. IFN-gamma or TNF-alpha alone had no demonstrable cytotoxic effects, whereas IFN-gamma and TNF-alpha in combination induced apoptosis drastically in Hepa1-6 cells. During this apoptosis, an increase in caspase-3- and -8-like protease activities and activation of caspase-3, identified by the appearance of its p17 fragment, were observed. Moreover, the cytotoxic induction and caspase-3 activation were effectively inhibited by Z-Asp-CH(2)-DCB (Z-Asp), a caspase inhibitor. Further, an elevation of cytochrome c in the cytosol, in a parallel to activation of caspase-3, was observed in a time-dependent manner. Concurrently, up-regulation of caspase-11 gene expression and processing of procaspase-11 were detected during this apoptosis. These results suggest that the caspase-3 activation, the release of cytochrome c from mitochondria, and increased caspase-11 gene expression involve in synergistic induction of apoptosis in Hepa1-6 cells by IFN-gamma and TNF-alpha.

Animals↗
PubMed2000

Regulation and significance of hepatocyte-derived matrix metalloproteinases in liver remodeling.

Regulation in expression and activation of proteinases is one of the most important mechanisms in organ morphogenesis. In this study, we investigated the expression of MMPs in primary hepatocytes and their roles in liver remodeling. A hepatocyte proliferation initiating cytokine, TNFalpha, induced MMP-9 expression in these cells while the expression of MMP-2 did not change by zymography analysis. Interestingly, both the induced MMP-9 expression and hepatocyte proliferation by TNFalpha were synergistically enhanced by HGF in vitro. The increased proliferation was suppressed by MMP inhibitor TIMP-1, suggesting that cytokine-induced MMP regulates proliferation. The increased expression of MMP-9 by the cytokines was inhibited by cytochalasin D or colchicine but not by PI3 kinase inhibitor wortmannin. In addition, co-stimulation by TNFalpha and HGF of spheroidal hepatocytes cultured in 3-dimensional collagen gel drastically induced morphological changes by cell extension and migration in the gel, which was in parallel with the induced expression of MMP-9 and was inhibited by TIMP-1 and -2. The MMP activity was also detected in vivo in the regenerating liver after partial hepatectomy by in situ zymography. These results suggest the roles of MMPs produced by parenchymal cells in liver remodeling.

Androstadienes↗
PubMed2000

S-nitrosylated human alpha(1)-protease inhibitor.

Alpha(1)-protease inhibitor (alpha(1)PI) is an acute phase plasma protein, and possesses a single cysteine residue at position 232. A single cysteinyl sulfhydryl of human alpha(1)PI is found to be readily S-nitrosylated by nitric oxide (NO) in vitro without affecting the inhibitory capacity against bovine trypsin or elastase, a major target protease of alpha(1)PI in vivo. S-nitroso-alpha(1)PI (S-NO-alpha(1)PI) was also formed by the reaction of alpha(1)PI with NO produced excessively by a murine macrophage cell line (RAW264 cells) upon infection with Salmonella typhimurium and in an ex vivo perfusion system of the liver obtained from lipopolysaccharide-treated rats. S-NO-alpha(1)PI (10(-9)-10(-6) M) induces a dose-dependent relaxation of the ring preparation of rabbit aorta. Also, S-NO-alpha(1)PI but not alpha(1)PI shows a potent inhibitory effect on platelet aggregation. Unprecedented observation is that S-NO-alpha(1)PI showed a potent bacteriostatic effect against a wide range of bacteria at the concentration of 1-10 microM, which was 10-1000-fold stronger than that of NO and other S-nitrosylated compounds including S-nitrosylated albumin and S-nitrosylated glutathione. These results suggest that S-NO-alpha(1)PI is produced as an NO sink under inflammatory conditions, where production of both alpha(1)PI and NO is highly up-regulated, and it may function as a soluble factor which consists of an innate defense system through not only the protease inhibitory activity but also its antibacterial activity and facilitating the peripheral blood flow. Therefore, S-nitrosylation of alpha(1)PI occurring under physiological conditions in vivo should diversify the biological functions contributing to cytoprotective effects of alpha(1)PI.

Animals↗
PubMed2000

Gd(3+)-loaded polyion complex for pH depiction with magnetic resonance imaging.

In clinical diagnosis, gadolinium (Gd) ion/low molecular weight chelater complexes have been used as MRI contrast agents that disperse throughout a particular tissue and cause a brighter appearance in MRI. In order to provide a novel imaging concept for MRI, a contrast agent in which the T(1)-relaxation shortening activity (R(1) relaxivity) changes in response to the pH differences was studied. We prepared a polyion complex (PIC) consisting of a polyanionic Gd-chelater, poly(diethylenetriamine-N,N,N',N", N"-pentaaceto, DTPA) (1,3-propanediamide) (denoted as 1a) loaded with Gd ions at a [Gd]/[DTPA unit] ratio of 0.2 (denoted as 1b), and a polycation, poly[2-(diethylamino)ethyl methacrylate] (denoted as 2). The stoichiometric (based on ionic groups) mixture of 1b and 2 formed complex coacervates from pH 5 to pH 8. The R(1) relaxivity of Gd(3+) in the complex was considerably influenced by the pH, and the relative signal intensity changed from 4 at pH 7.2 to 11 at pH 5.0, as determined by an MRI phantom study. The pH responsivity of the complex solution varied with the composition of the PIC (i.e., the mixing ratio of 1b and 2), allowing us to modulate the pH sensibility. The ionic charge balance and swelling of PIC seemingly were related to the pH-dependent R(1) relaxivity change. It is expected that the PIC-based MRI contrast agent may provide a novel category of MRI methods and be useful in improving the detectability of an MRI-based diagnosis.

Cations↗
PubMed2000

Matrices for tissue engineering-scaffold structure for a bioartificial liver support system.

This study proposes a new composite scaffold system. A woven polyethylenterephtalate (PET) fabric was coated on one side with a biodegradable PLGA film, in order to obtain a geometrically polarized scaffold structure for an bioartificial liver support system. The composite structure ensures the stability of the membrane during degradation of the membrane polymer. The mesh size of the composite does not significantly influence the degradation behavior. Hepatocyte culturing studies reveal that the formation of aggregates depends on the mesh size and on the pretreatment: The largest aggregates could be observed after 48 h when PVLA coating, large mesh size and EGF were combined. Thus, the combination of a geometrically structured, partially degradable scaffold with receptor-mediated cell attachment sites offers promising possibilities in liver tissue engineering.

Animals↗
PubMed2000

Tumor-targeting chemotherapy by a xanthine oxidase-polymer conjugate that generates oxygen-free radicals in tumor tissue.

Xanthine oxidase (XO) mediates anticancer activity because of its ability to generate cytotoxic reactive oxygen species (ROS), including superoxide anion radical and hydrogen peroxide. However, the high binding affinity of XO to blood vessels would cause systemic vascular damage and hence limits the use of native XO in clinical settings. We demonstrate here that chemical conjugation of XO with poly(ethylene glycol) (PEG; the conjugates hereafter referred to as PEG-XO) significantly enhanced the tumor-targeting efficacy and the antitumor activity of XO. By using a succinimide-activated PEG derivative, PEG was conjugated to epsilon-amino groups of lysine residues of XO, which play a crucial role in binding of XO to blood vessels. PEG-XO administered i.v. showed a 2.8-fold higher accumulation in solid tumor compared with that of native XO 24 h after injection, whereas a slight or negligible increase in accumulation of PEG-XO was observed in normal organs. The highest PEG-XO enzyme activity was detected in tumor compared with normal organs or tissues except blood; enzyme activity in tumor was 5.0, 3.9, and 9.4 times higher than that in liver, kidney, and spleen, respectively. Intratumor activity remained high for >48 h. Administration of hypoxanthine, a substrate of XO, at 33 mg/kg body weight i.p. 12 h after the administration of PEG-XO (0.6 unit/mouse, i.v.) resulted in significant suppression of tumor growth (P < 0.001), with no tumor growth even after 52 days. However, either PEG-XO or hypoxanthine alone, or native XO with hypoxanthine, showed no effect on the inhibition of tumor growth under present experimental conditions. These findings suggest that PEG-XO, which accumulates preferentially in tumor tissue, warrants further investigation as a novel anticancer agent.

Animals↗
PubMed2000

Novel functions of human alpha(1)-protease inhibitor after S-nitrosylation: inhibition of cysteine protease and antibacterial activity.

alpha(1)-Protease inhibitor (alpha(1)PI), the most abundant serine protease inhibitor found in human plasma (at 30-60 microM), is a glycoprotein (53 kDa) having a single cysteine residue at position 232 (Cys(232)). We have found that Cys(232) of human alpha(1)PI was readily S-nitrosylated by nitric oxide (NO) without affecting inhibitory activity to trypsin or elastase. S-nitrosylated alpha(1)PI (S-NO-alpha(1)PI) not only retained inhibitory activity against these serine proteases, but also gained thiol protease inhibitory activity against a Streptococcus pyogenes protease; the parental alpha(1)PI did not have this activity. Furthermore, S-NO-alpha(1)PI exhibited bacteriostatic activity against Salmonella typhimurium at concentrations of 0.1-10 microM, which were 20- to 3000-fold stronger than those of the other NO-generating compounds or S-nitroso compounds such as S-nitrosoalbumin and S-nitrosoglutathione. NO appears to be transferred into the bacterial cells from S-NO-alpha(1)PI via transnitrosylation, as evidenced by electron spin resonance spectroscopy with an NO spin trap. Thus, we conclude that S-NO-alpha(1)PI may be generated from the reaction between alpha(1)PI and NO under inflammatory conditions, in which production of both is known to increase. As a result, new functions, i.e., antibacterial and thiol protease inhibitory activities of alpha(1)PI, were generated.

Animals↗