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Biomedical subjects

T Yamakawa

Publications and source records attributed to T Yamakawa.

At least 19 recordsLinked to original sources
PubMed1992

Activation of Ca2+/calmodulin-dependent protein kinase II by stimulation with bradykinin in neuroblastoma x glioma hybrid NG108-15 cells.

To elucidate the mechanisms of the intracellular signal transduction elicited with bradykinin in NG108-15 neuroblastoma x glioma hybrid cells, we examined the activation of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) by bradykinin stimulation. When the extract of NG108-15 cells was immunoprecipitated with the affinity-purified antibody to brain CaM kinase II, a 50-kDa protein in the immunoprecipitate mainly became autophosphorylated in a Ca2+/calmodulin-dependent manner. The results suggest that the 50-kDa protein is the subunit of CaM kinase II in NG108-15 cells. The Ca2+/calmodulin-independent activity (autonomous activity) of the enzyme increased twice within 10 s by stimulation with 1 microM bradykinin in the cells. The increase in the autonomous activity of the enzyme had two phases: the transient early-peak phase and the long late-plateau phase. The former was abolished by the pretreatment of the cells with 10 mM caffeine or 20 microM BAPTA-AM, and the latter was abolished by the removal of the extracellular Ca2+ with 1 mM EGTA or by the pretreatment with 1 microM nifedipine. Stimulation of 32P-labeled NG108-15 cells with 1 microM bradykinin increased the autophosphorylation of CaM kinase II and this increase was abolished by pretreatment with caffeine or BAPTA-AM. These results suggest that CaM kinase II is activated via the inositol phospholipid signaling pathway induced with bradykinin in NG108-15 cells.

Bradykinin↗
PubMed1992

A fuzzy logic controller.

This paper describes a fuzzy sets method which is very useful for handling uncertainties and essential for knowledge acquisition of a human expert. Kinetics of a reactor is often complex and not trivial to describe by mathematical equations. Reactor control by traditional control technology is therefore difficult. A novel technology is presented. In the following a fuzzy inference (approximate reasoning) is used for decision making in analogy to human thinking, facilitating a more sophisticated control. Readers of this paper do not need any advanced mathematics beyond the four basic operations in arithmetic (+, -, x, divided by) and using the maximum and minimum values. This fuzzy inference is introduced to construct a fuzzy logic controller which is suitable for a nonlinear, multivariable and time variant system applied to a bioreactor.

Biotechnology↗
PubMed1992

Fistuloscopy for the management of postoperative intra-abdominal abscesses.

A new technique of fistuloscopy for evaluation and treatment of postoperative intra-abdominal abscesses is described which was used in 8 patients in whom drainage of abscesses following surgery was insufficient. A cholangiofiberscope was introduced into the fistula canal produced by the postoperative drainage. Fistuloscopy was combined with fistulography in all cases to delineate the extent of the inflammatory process. The guidewire was then placed under visual control through the endoscope followed by re-introduction of the drainage tube until a position most effective for pus drainage was achieved. Following this procedure, fever resolved in all 8 patients. Fistuloscopy is recommended to achieve sufficient drainage of intra-abdominal abscesses in those cases where percutaneous ultrasound- or CT-guided drainage fails to lead to significant clinical improvement.

Abscess↗
PubMed1992

Preliminary experience using an ultrasonic aspirator for laparoscopic cholecystectomy.

An ultrasonic aspirator (Olympus) specially designed for laparoscopic surgery, which also includes cautery and suction-irrigation systems, was evaluated in 40 patients undergoing laparoscopic cholecystectomy. The generating power of each system is controlled by hand or foot switches, and most operating procedures could easily be performed through a 10 mm trocar inserted through the abdominal wall. The ultrasonic aspirator successfully fragmented and aspirated soft tissue, allowing a precise differentiation between the cystic duct and artery, small vessels, lymphatics and fibrous tissue. Removal of the gallbladder could be performed successfully using the cautery and ultrasonic aspirator, whereby parts of cauterization or division could easily be identified. Identification of the cystic duct and artery, course of the cystic duct and Hartmann's pouch in the same field of vision was possible which is important for avoiding major complications such as injury of the common bile duct. No complications were seen during or after surgery in any of the patients.

Cholecystectomy, Laparoscopic↗
PubMed1992

Synthesis and structure-activity relationships of substituted 2-[(2-imidazolylsulfinyl)methyl]anilines as a new class of gastric H+/K(+)-ATPase inhibitors. II.

A series of 2-[(2-imidazolylsulfinyl)methyl]anilines (2) having various substituents on their imidazole and aniline rings was synthesized and examined for their H+/K(+)-ATPase (adenosine triphosphatase) inhibitory effects and antisecretory activity against histamine-stimulated gastric acid secretions in Heidenhain pouch dogs. Although substitutions on the imidazole ring did not enhance biological activity, substitutions on the aniline ring by electron-donating substituents potently enhanced the enzyme inhibitory activity and also showed an inhibitory effect on histamine-stimulated gastric acid secretion after oral administration. In particular, the in vitro activity of the dimethyl (2u--w) and trimethyl (2ac) derivatives was about 10 times that of omeprazole. Also, 4-methyl (2k), 4-methoxy-5-methyl (2y) and 3,5-dimethyl-4-methoxy (2ab) derivatives showed a potent antisecretory effect of more than 80% after oral administration at 6 mg/kg. Although these aniline derivatives have relatively low stabilities in aqueous solution, replacement of the isobutyl group at the aniline nitrogen atom with N-(2-methoxyethyl) group enhanced the stability.

Adenosine Triphosphatases↗
PubMed1992

[Experimental study on the effect of injection with anticancer agent-oil suspension].

Local injection of an anticancer agent guided by endoscopy is thought to be effective for cancerous lesion associated with lymph node metastasis, if the anticancer drugs are drained into the lymph nodes. In the experimental study, anticancer drug-oil (nimustine-Lipiodol) (N-L) suspension (5 mg/ml) was injected into the tumor (Lewis lung cancer) that had been implanted sub dorsally in mice (57 black/6 mice) for the purpose of finding out the antitumor effect on the primary lesion. Then it was injected into sarcoma-180 that had been implanted into hind feet of mice (ICR mice) for the purpose of finding out the antitumor effect on metastatic lymph nodes. The results showed that the N-L suspension was effective for the primary cancerous lesion and metastatic lesions.

Animals↗
PubMed1992

Experimental model with bilioenteric anastomosis in rats--technique and significance.

A simple technique of hepaticojejunostomy in rats is introduced in this paper and its suitability for use as an experimental model was evaluated histologically. Hepaticojejunostomy was performed as follows; the stump of the supra-pancreatic common bile duct (CBD), detached from adjacent tissue, was introduced into the jejunal lumen using the outer catheter previously inserted into the jejunum, and the jejunal wall close to the implantation site of the CBD was fixed to the porta hepatitis with a suture. Among 40 rats in which hepaticojejunostomy was performed, the postoperative mortality rate was 17.5%. The remaining experimental animals (33 rats, 82.5%) survived for the duration of this study. The rats were sacrificed at 3, 5, 8, and 12 months after surgery, and liver function tests, macroscopic and histological studies of the biliary tract were carried out. No signs of cholangitis or liver abscess were noted in any experimental animals during this period. The median values of liver function tests were within normal limits in almost all of the experimental rats. The anastomotic stoma was also patent, and free drainage of bile was noted, but the bile duct proximal to the site of anastomosis was generally macroscopically dilated. Histologically, epithelial hyperplasia and fibrous thickening of the wall accompanied by inflammatory cell infiltration were noted in the rats sacrificed at 3 and 5 months postoperatively. Marked hyperplasia of mucous glands, goblet cell metaplasia and atypical epithelium were usually seen in the rats killed at 8 months and 12 months after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1992

Red cell velocity and microvessel diameter measurement by a two fluorescent tracer method under epifluorescence microscopy: application to cerebral microvessels of cats.

Fluorescein isothiocyanate (FITC)-labeled red blood cells (RBCs) and rhodamine-B isothiocyanate (RITC)-labeled dextran were used as two fluorescent tracers under intravital fluorescence microscopy. RBC velocity in cerebral microvessels of cats was measured with a dual window technique using FITC-labeled RBCs as a flow tracer. Measurement of the vessel diameter was performed using a digital image processor system by staining plasma with RITC-labeled dextran. The RBC velocity, obtained directly with digital cross-correlation of videodensitometric signals derived from the two windows, coincided with those obtained with the frame-by-frame analysis. The obtained RBC velocity ranged between 12.9 and 0.45 mm/sec in arterioles (< 60 microns) in diameter, 4.2 and 0.18 mm/sec in venules (< 60 microns in diameter), and 1.1 and 0.26 mm/sec in capillaries. The use of the labeled RBCs as the flow tracer enabled us to measure a wide range of RBC velocity (up to about 7 mm/sec) by setting the distance between the two windows beyond about 200 microns.

Animals↗
PubMed1991

Stable expression of human tissue-type plasminogen activator regulated by beta-actin promoter in three human cell lines: HeLa, WI-38 VA13 and KMS-5.

A high-level and stable expression system of human tissue-type plasminogen activator (t-PA) was accomplished in human cells by selecting a promoter and a host cell line. First, we have constructed two types of t-PA expression plasmids containing 3 kb of the human beta-actin promoter region or 0.3 kb of SV40 early promoter region and these plasmids were transfected into HeLa cells, respectively, and the resulting transfectants were found to secrete various amounts of t-PA derived from the plasmids to the culture media. Southern blot analysis revealed that the beta-actin promoter was more efficient than the SV40 early promoter with regard to the expression level per single copy of the t-PA gene in the transfected HeLa cells. Next, the t-PA expression plasmid containing the beta-actin promoter was also transfected into WI-38 VA13 cells, a human fibroblastic cell line, and KMS-5 cells, a human lymphoid cell line, in order to compare the expression ability of the promoter among these three cell lines. Some of the transfectants from both cell lines were also found to produce t-PA. It was also found that the expression levels in HeLa and WI-38 VA13 seemed to be more efficient than that in KMS-5.

Actins↗
PubMed1991

Two pathways for GM2(NeuGc) expression in mice: genetic analysis.

We have reported that WHT/Ht mice express neither GM2(NeuGc) nor GM1(NeuGc) in the liver or erythrocytes due to a defect on the Ggm-2 gene, which was demonstrated to control the activity of UDP-GalNAc:GM3(NeuGc) N-acetylgalactosaminyltransferase in mouse liver, and, in addition, WHT/Ht mice do not express a detectable amount of GM2(NeuGc) but do express GM1(NeuGc) in tissues other than the liver and erythrocytes, such as the spleen, thymus, heart, lung, kidney, and testis [Nakamura et al. (1988) J. Biochem. 103, 201-208]. In order to determine whether the phenotype of WHT/Ht mice exhibiting an undetectable amount of GM2(NeuGc) in these tissues is genetically controlled or not, we analyzed the expression of gangliosides in the progeny obtained on backcross mating between (BALB/c X WHT/Ht)F1 and WHT/Ht mice, and in a GM2(NeuGc) congenic mouse, WHT.C. Concerning the expression of GM2(NeuGc) in the liver, lung, and kidney, 102 backcross mice could be segregated into two types. One type expressed a detectable amount of GM2(NeuGc) in the liver, lung, and kidney, and the other type did not. The ratio of the numbers of mice exhibiting these two types was 42: 60, indicating that the two phenotypes were genetically determined by the involvement of a single autosomal gene. Recombination as to GM2(NeuGc) expression in the liver, lung, and kidney was not detected among the 102 backcross mice. Analysis of the GM2(NeuGc) congenic mouse indicated that a detectable amount of GM2(NeuGc) was expressed in the liver, erythrocytes, lung, kidney, heart, spleen, and small intestine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

A micro method involving micro high-performance liquid chromatography-mass spectrometry for the structural characterization of neutral glycosphingolipids and monosialogangliosides.

A micro method involving high-performance liquid chromatography-fast atom bombardment mass spectrometry (HPLC/FAB/MS) has been developed for the sensitive structural characterization of neutral glycosphingolipids and monosialogangliosides. The method involves a micro silica gel column (0.3 mm i.d. x 100 mm) and a micro HPLC apparatus working at a flow rate of 6 microliters/min. All injected materials can be structurally characterized by mass spectrometry without the splitting or wasting of materials, which was not possible with our previous method [M. Suzuki et al. (1990) J. Biochem. 108, 92-98]. A mixture containing 160 ng each of five neutral glycosphingolipids (GlcCer, LacCer, Gb3Cer, Gb4Cer, and IV3 alpha GalNAc-Gb4Cer) and a mixture containing 160 ng each of three monosialogangliosides [GM3(NeuAc), GM2(NeuAc), and GM1(NeuAc)] were injected into the micro HPLC with programmed elution with isopropanol-n-hexane-water with or without ammonium hydroxide. Each glycosphingolipid was separated by mass chromatography and the obtained mass spectra were suitable for structural characterization. Thus, the characterization of glycosphingolipids was achieved with small amounts of materials, 160 ng each, and in mixtures.

Chromatography, High Pressure Liquid↗
PubMed1991

Reconstitution of CMP-N-acetylneuraminic acid hydroxylation activity using a mouse liver cytosol fraction and soluble cytochrome b5 purified from horse erythrocytes.

The hydroxylation of CMP-N-acetylneuraminic acid (CMP-NeuAc) in the formation of CMP-N-glycolylneuraminic acid requires several components which comprise an electron transport system. A protein, which replaces one of the components, was purified to homogeneity from a horse erythrocyte lysate. Based on its partial amino acid sequence and immunological cross-reactivity, this protein was identified as soluble cytochrome b5 lacking the membrane domain of microsomal cytochrome b5. The electron transport system involved in CMP-NeuAc hydroxylation was reconstituted, and then characterized using the purified horse soluble cytochrome b5 and a fraction from mouse liver cytosol. The hydroxylation reaction requires a reducing reagent, DTT being the most effective. Either NADH or NADPH was used as an electron donor, but the activity with NADPH amounted to about 74% of that with NADH. The hydroxylation was inhibited by salts and azide due to interruption of the electron transport from NAD(P)H to cytochrome b5 and in the terminal enzyme reaction, respectively.

Amino Acid Sequence↗
PubMed1991

A sialidase-susceptible ganglioside, IV3 alpha(NeuGc alpha 2-8NeuGc)-Gg4Cer, is a major disialoganglioside in WHT/Ht mouse thymoma and thymocytes.

The disialogangliosides of WHT/Ht mouse thymomas, which were obtained by subcutaneous transplantation of a thymoma that developed spontaneously in a WHT/Ht mouse, were purified and characterized. From the results of sugar-composition analysis, a permethylation study, enzymatic hydrolysis followed by TLC-immunostaining, negative-ion fast atom bombardment mass spectrometry (FAB/MS), and 1H-NMR spectroscopy, the structure of one of the five purified disialogangliosides was determined to be IV3 alpha(NeuGc alpha 2-8NeuGc)-Gg4Cer. The other 4 disialogangliosides were tentatively characterized on the basis of sialidase treatment followed by TLC-immunostaining with cholera toxin B subunit and anti-Gg4Cer antibody to be IV alpha(NeuAc alpha-NeuGc)-Gg4Cer, IV alpha(NeuGc alpha-NeuAc)-Gg4Cer, IV alpha NeuAc,II3 alpha NeuAc-Gg4Cer, and IV alpha NeuGc,II3 alpha NeuGc-Gg4Cer. In addition, another component exhibiting one spot on TLC was a mixture of IV alpha NeuGc,II3 alpha NeuAc-Gg4Cer and IV alpha NeuAc,II3 alpha NeuGc-Gg4Cer. Then the occurrence of these gangliosides in WHT/Ht mouse thymocytes was examined. As one of two major disialogangliosides, the thymocytes contained IV3 alpha(NeuGc alpha 2-8NeuGc)-Gg4Cer, which was characterized with a mass spectrum and mass chromatograms obtained by micro high-performance liquid chromatography-FAB/MS. The other major disialoganglioside was tentatively characterized to be II3 alpha-(NeuGc alpha-NeuGc)-Gg4Cer by sialidase treatment followed by TLC-immunostaining. A sialidase-susceptible monosialoganglioside, IV3 alpha NeuGc-Gg4Cer [GM1b(NeuGc)], had been reported to be characteristic of mouse immune tissues [Nakamura, K. et al. (1988) J. Biochem, 103, 201-208]. Taken together, the results suggest that the pathway from Gg4Cer to IV3 alpha(NeuGc alpha 2-8NeuGc)-Gg4Cer through GM1b(NeuGc) is quite active in mouse immune tissues.

Animals↗
PubMed1991

Vascular responsiveness to various vasoactive substances after exchange transfusion with pyridoxalated hemoglobin polyoxyethylene conjugate (PHP) solution in anesthetized rats.

Vascular responsiveness to various vasoactive substances after exchange transfusion with a modified hemoglobin (pyridoxalated hemoglobin polyxyethylene conjugate; PHP) was examined in anesthetized rats. The hindlimb region of the rat was perfused through the abdominal aorta with autologous blood at a constant flow rate, using a perfusion pump. Perfusion pressure (PP), systemic blood pressure (SBP), and heart rate were measured. Exchange transfusion with a 6% PHP solution (20 ml/kg) was performed and effects of intra-arterial injections of norepinephrine (NE), angiotensin-II (A-II), serotonin (5-HT), acetylcholine (ACh), and nitroglycerin (NG) on PP and SBP were examined. The NE and A-II induced a dose-dependent increase in PP, while ACh and NG induced a decrease in PP. There was no difference in vascular responsiveness to ACh, NG, A-II, and 5-HT before and after exchange transfusion with PHP solution, but NE-induced responses were augmented after exchange transfusion with PHP. Results suggest that the presence of PHP moiety in circulation would not alter vascular responsiveness to ACh, NG, A-II, and 5-HT in a significant manner.

Anesthesia, General↗
PubMed1991

Synthesis and structure-activity relationships of N-substituted 2-[(2-imidazolylsulfinyl)methyl]anilines as a new class of gastric H+/K(+)-ATPase inhibitors.

A series of N-substituted 2-[(2-imidazolylsulfinyl)methyl]anilines (3) was synthesized and evaluated for its biological activity against gastric H+/K(+)-ATPase prepared from rabbit stomach and gastric acid secretions in Heidenhain pouch dogs. Monoalkyl substituents on the nitrogen atom of the aniline moiety markedly inhibited the enzyme activity to the same degree as omeprazole, a representative H+/K(+)-ATPase inhibitor. Most of these compounds, administered at 3 mg/kg i.v. inhibited histamine-stimulated gastric acid secretion. The inhibitory activity of these derivatives on the enzymes at pH 6.0 was more potent than that at pH 7.4, and was distinctly correlated to stability in aqueous solution at pH 5.0.

Adenosine Triphosphatases↗
PubMed1991

[Regulation of Ca2+/calmodulin-dependent protein kinase II in the cell systems in response to cellular stimuli].

Calcium ion (Ca2+) is considered to be involved in the regulation of numerous cellular processes. CaM kinase II is present at the highest concentration in the brain and is considered to be involved in the regulation and coordination of numerous cellular processes. CaM kinase II is activated by Ca2+/calmodulin and simultaneously undergoes autophosphorylation. It has not been determined whether the enzyme is activated in the cell systems in response to the increase in cytoplasmic Ca2+ concentration. We have studied CaM kinase II in several kinds of cells including the primary cultures of cerebellar granule cells and the cell lines of rat embryo fibroblast 3Y1 cells, neuroblastoma cells, PC12 cells and C6 glioma cells. The immunohistochemical analysis demonstrated the presence of CaM kinase II in all of the cells examined. Furthermore, the kinase in cerebellar granule cells was activated by the stimulation of the glutamic acid receptor. Autophosphorylation of CaM kinase II in 3Y1 cells was stimulated by the addition of growth factors. These results suggest that CaM kinase II undergoes activation and autophosphorylation in response to various stimuli to the cells and is regulated in the dynamic state.

Amino Acid Sequence↗
PubMed1991

[Image diagnostics for carcinoma of the biliary tract].

Although it is clear that US is the procedure which should be selected as a method of the first choice to detect carcinoma of the biliary tract, a rational selection and combination of diagnostic procedures are essential for further evaluation on the nature or extension of tumor and its resectability. The next procedure which should be selected after US, in our opinion, is ERCP which can be followed by ERBD, if necessary, because it is useful to know the site and extension of tumor. However, the cases who have the lesion at the upper portion of the biliary tract or which is considered to be unresectable should be converted to percutaneous transhepatic approaches (PTC, PTBD, PTCS) at this stage as a method of next choice with diagnostic and subsequent therapeutic purposes. On the other hand, EUS is also an important first line diagnostic procedure to delineate the lesion at the lower portion of the biliary tract which can be used in parallel with ERCP. In this paper, usefulness of EUS was strongly advocated, because the information concerning the extension and resectability of tumor are also provided with it as it is obtained with CT, MRT and angiography. Cytology of bile, cholecystography, percutaneous transhepatic cholangioscopy and biopsy under endoscopic control carried out after percutaneous transhepatic drainage of the gallbladder are the procedures used for the diagnosis of gallbladder carcinoma, but they should be only indicated in the cases, in which early carcinoma is strongly suspected, because it cannot provide us any information necessary to make therapeutic plan in the cases with advanced carcinoma.

Biliary Tract Neoplasms↗