Biomedical subjects

Y Suzuki

Publications and source records attributed to Y Suzuki.

At least 19 recordsLinked to original sources

PubMed1992

[Experimental study of indirect lymphography with iodinated starch].

Opacification of lymph nodes on CT was attempted by means of indirect lymphography with iodinated starch (IS). Sixty percent solutions of two different molecular weights of IS were prepared (5,000 mol wt and 70,000 mol wt in average). After subcutaneous injection of IS solutions to the pedal area of dogs, CT scans were performed to evaluate opacification of the popliteal lymph nodes. The lymph nodes began to be opacified from 10 min after the injection of each solution. The high molecular weight IS showed higher attenuation and longer duration of opacification than did the low molecular weight IS. Homogeneity of opacification was better with latter. The optimum molecular weight for this purpose is considered to be between 5,000 and 70,000 mol wt.

Animals↗

PubMed1992

Participation of calpain I activation in the ATP release reaction of platelets stimulated with thrombin.

Proteolytic activation of calpain (calcium-dependent neutral protease) I in thrombin-stimulated platelets was determined by following the production of the 76- and 78-kDa forms from the 80-kDa subunit of calpain I as measured by immunoblotting using monospecific antibody to human calpain I, and the correlation between the extents of calpain I activation and ATP release was investigated. When platelets were stimulated with thrombin in the range from 0.01 to 0.5 U/ml, the maximal 60% activation of calpain I was achieved within 15 s after the stimulation, and ATP release began after the maximal activation had been reached. The extent of ATP release decreased in parallel with the decrease in activation ratio of calpain I on treatment of platelets with EGTA or EST, a membrane-permeable inhibitor of calpain. Although pretreatment of platelets with EST did not affect the thrombin-dependent elevation of the cytosolic Ca2+ concentration, both the inhibition of calpain I activation and the reduction of ATP release were observed as a function of EST concentration. These results suggest that calpain I participates in one of the processes leading to the ATP release reaction of platelets stimulated with thrombin.

Adenosine Triphosphate↗

PubMed1992

Stimulation of glucose transport by guanine nucleotides in permeabilized rat adipocytes.

Effects of guanine nucleotides on glucose transport were studied in permeabilized rat epididymal fat cells. GTP gamma S and Gpp(NH)p, but not App(NH)p, stimulated 3-O-methylglucose transport. Effect of GTP gamma S was dose-dependent, being detectable at 0.1 mM, and 1.0 mM GTP gamma S stimulated glucose transport to the same extent as insulin. GTP gamma S (0.3 mM) enhanced insulin-stimulated glucose transport while 1 mM GTP gamma S did not affect insulin-mediated transport. GDP beta S had no effect on glucose transport by itself but rather enhanced insulin action. NaF, which is known to activate trimeric G proteins, increased glucose transport to the same extent as insulin. Likewise, mastoparan augmented glucose transport. These results indicate that a certain type of trimeric G protein(s) is involved in the regulation of glucose transport.

3-O-Methylglucose↗

PubMed1992

Capillary gas chromatographic method for the determination of the thromboxane A2 receptor antagonist S-1452 and its metabolites in human urine.

A capillary gas chromatographic method using a sulphur-specific detector (Hall's electrolytic conductivity detector) was established to determine the thromboxane A2 antagonist S-1452 and its metabolites in human urine. The target species were the free acid (+)-S-145 of the drug and its nine metabolites: the three hydroxyl forms of (+)-S-145 (I, II and III), bis-nor-(+)-S-145 (IV) the hydroxylated forms of IV (V and VI), tetranor-(+)-S-145 (VII) and the hydroxylated forms of VII (VIII and IX). These ten compounds, which have the same sulphur-containing functional group in common, were determined simultaneously. Their conjugated forms, which were assumed to be glucuronides, were also assayed after hydrolysis. The first derivatization was esterification with diazomethane. The second, for the hydroxylated compounds, was trimethylsilylation with bis(trimethylsilyl)trifluoroacetamide. The ten analytes appeared as separate peaks without mutual interference during 5 min. Hall's detector distinguished the ten analytes selectively from the other urinary components, which removed the need for complex clean-up procedures and led to higher sensitivity with a lower noise level. The method is sensitive enough for the assay of substances present at more than 0.1 micrograms/ml of urine. All the compounds could be determined with a high level of precision and accuracy, with 2-5% relative standard deviation and within +/- 5% deviation from the actual value. Day-to-day measurements verified the reproducibility of the method. Recovered substances were quantified by following the time course, and the analytical data together with previously obtained plasma data clarified the metabolism pharmacokinetically.

Bridged Bicyclo Compounds↗

PubMed1992

A synthetic peptide corresponding to 86-93 of the human type I IL-1 receptor binds human recombinant IL-1 (alpha and beta) and inhibits IL-1 actions in vitro and in vivo.

A synthetic peptide corresponding to 86-93 of the human type I IL-1 receptor and its analogues bound human recombinant (hr) IL-1 (alpha and beta) and inhibited dose-dependently both Con A-stimulated proliferation of mouse spleen cells and hrIL-1 beta-stimulated formation of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells in rat bone marrow cell cultures. Furthermore, hrIL-1 beta-induced mouse paw edema was dose-dependently inhibited by systemic administration (ip) of the synthetic peptide. These results suggest that one of the IL-1 binding sites of the human type I IL-1 receptor comes to the region of 86-93 and the synthetic peptide having the ability to bind hrIL-1 (alpha and beta) blocks the biological activities of exogenous hrIL-1 beta and endogenous mouse IL-1.

Amino Acid Sequence↗

PubMed1992

Biosynthesis and degradation of altered immature forms of intestinal dipeptidyl peptidase IV in a rat strain lacking the enzyme.

We have used a strain of rat (Fischer 344) lacking brush border membrane dipeptidyl peptidase IV activity to examine its effect on the intestinal assimilation of prolyl peptides. In addition, we have examined the biochemical basis for the enzyme deficiency. An analysis of several brush border membrane hydrolases in different regions of the small intestine demonstrates that these rats lack only dipeptidyl peptidase IV. They also have a greatly reduced ability to hydrolyze and absorb in vivo peptides of the NH2-X-Pro-Y type which are known substrates for the enzyme. Immunoblot analysis with polyclonal and monoclonal antibody indicates that the animals lack an identifiable dipeptidyl peptidase IV protein in intestinal epithelial cells. Levels and types of dipeptidyl peptidase IV mRNA were analyzed in several tissues and found to be similar to that of control animals. Biosynthetic labeling of intestinal explants revealed that two distinct forms (102 and 108 kDa) of dipeptidyl peptidase IV are initially synthesized by deficient rats, in contrast to the single protein (106 kDa) observed in normal animals. Pulse-chase labeling experiments (+/- endoglycosidase H) show that these two altered forms of dipeptidyl peptidase IV, although initially glycosylated with N-linked high mannose carbohydrate, fail to be processed to the mature complex glycosylated form and undergo intracellular degradation.

Amino Acid Sequence↗

PubMed1992

Purification and characterization of a rat liver protein-tyrosine phosphatase with sequence similarity to src-homology region 2.

Utilizing three proteins plus tyrosine-glutamate copolymer as substrates, all of which are subjected to (near) stoichiometrical phosphorylation exclusively on tyrosine residues, we partially purified four different protein-tyrosine phosphatases (PTPases) from rat liver cytosol which differed in substrate preference. Of the four PTPases, tentatively termed L1, L2, L3, and L4, PTPase L1 was purified to apparent homogeneity by a procedure involving chromatography on DEAE-cellulose at pH 7.0, Blue Sepharose, DEAE-cellulose at pH 7.6, hydroxyapatite, Phenyl Sepharose, Mono Q, and TSKgel Heparin. PTPase L1 was purified about 7000-fold from the extract and 0.27 mg was isolated from 1000 g liver corresponding to a yield of 13% from the Blue Sepharose step where it had become freed from any other PTPases detectable by our assay procedure. The purified PTPase L1 showed a major protein band of 67 kDa on SDS/PAGE. Catalytically, PTPase L1 had a specific activity of about 6500 nmol Pi released min-1mg-1 toward tyrosine-glutamate copolymer phosphorylated on tyrosine residues. PTPase L1 exhibited very low sensitivities to PTPase inhibitors such as zinc acetate, sodium vanadate, and acidic compounds as compared with those of most of the PTPases purified thus far. Amino acid sequence analysis of the purified PTPase L1 revealed a partial peptide sequence showing similarity to the catalytic domain core sequences conserved in the PTPase family. PTPase L1 was most similar to a PTPase termed PTP1C encoded by a human breast carcinoma cDNA but the identity was 55% over 117 residues spanning nearly half of the catalytic domain of PTP1C. The analysis also revealed another partial peptide sequence (113 residues) 70% identical with the sequence corresponding to 68% of two adjacent copies of the src homology region 2(SH-2 domain) identified in PTP1C. Besides those peptide sequences, PTPase L1 had regional sequences which were 70-90% identical with the residues lying between the two SH-2 domains or between the more C-terminal SH-2 domain and the catalytic domain of the carcinoma PTPase.

Amino Acid Sequence↗

PubMed1992

Possible prophylactic potential of HA1077, a Ca2+ channel antagonist and vasodilator, on chronic cerebral vasospasm.

We examined the possible prophylactic potential of HA1077, a calcium antagonist and vasodilator, on chronic cerebral vasospasm induced in a two-hemorrhage canine model, and also its effects on cerebral hemodynamics. The intravenous infusion of HA1077 3 mg/kg over 30 min twice daily (day 1-day 7) after the first intracisternal injection of 5 ml autologous blood significantly prevented the occurrence of chronic cerebral vasospasm. The mean diameter of the basilar arteries on day 7 was 66.1 +/- 1.6% (n = 7) of the baseline before the intracisternal injection of blood, compared to 54.2 +/- 1.6% (n = 9) of the baseline in the untreated group (P less than 0.01). Bolus intravenous administration of HA1077 (0.1 and 0.3 mg/kg) dose dependently increased local cerebral blood flow. Since HA1077 prevents the development of chronic cerebral vasospasm after subarachnoid hemorrhage and improves hemodynamic functions, as manifested by increases in local cerebral blood flow, further study is warranted regarding the possible clinical use of this drug.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1992

Different utilization of Ca2+ in the contractile action of endothelin-1 on cerebral, coronary and mesenteric arteries of the dog.

Vasoconstrictor responses to endothelin-1 (ET) were compared between endothelium-denuded strips of cerebral, coronary and mesenteric arteries of the dog. Contractile responses to lower concentrations (below 3 x 10(-10) M) of ET were significantly greater in the cerebral and coronary arteries than in the mesenteric artery. The cerebral and coronary arteries, but not the mesenteric artery, relaxed significantly from the resting level when placed in a 0-Ca solution. Readdition of Ca2+ to the cerebral and coronary arteries placed in the 0-Ca solution caused a biphasic contraction which was susceptible to inhibition by nifedipine. When ET below 10(-10) M was introduced before the Ca2+ contraction, this peptide produced no detectable contraction, but augmented the Ca2+ contraction. The augmented Ca2+ contractions were abolished by 10(-7) M nifedipine. These effects of ET were not observed in the mesenteric artery. The contractile responses of the mesenteric artery to ET determined in the presence of elevated extracellular K+ concentrations were comparable to the responses of the cerebral artery to this peptide determined in the presence of normal K+ concentrations. These results indicate that the enhanced responses to ET in the cerebral and coronary arteries were dependent on the Ca2+ influx through voltage-dependent Ca2+ channels and suggest that these channels are in an activated state when these arteries are in a resting state.

Animals↗

PubMed1992

Cross-protection against influenza virus infection afforded by trivalent inactivated vaccines inoculated intranasally with cholera toxin B subunit.

Cross-protection against influenza virus infection was examined in mice, immunized intranasally with a nasal site-restricted volume of inactivated vaccines together with cholera toxin B subunit (CTB) as an adjuvant. The mice were challenged with either a small or a large volume of mouse-adapted virus suspension, each of which gave virgin mice either a predominant upper or lower respiratory tract infection. A single dose of a monovalent influenza A H3N2 virus vaccine with CTB provided complete cross-protection against the small-volume challenge with a drift virus within the same subtype, but a slight cross-protection against the large-volume challenge. A second dose of another drift virus vaccine increased the efficacy of cross-protection against the large-volume challenge. Similar cross-protection against H1N1, H3N2, or B type drift virus challenge was provided in the mice having received a primary dose of a mixture of H1N1, H3N2, and B virus vaccines with CTB and a second dose of another trivalent vaccine. The degree of cross-protection against the small- and the large-volume infection paralleled mainly the amount of cross-reacting IgA antibodies to challenge virus hemagglutinin in the nasal wash and that of cross-reacting IgG antibodies in the bronchoalveolar wash, respectively. On the other hand, in mice immunized subcutaneously with the trivalent vaccines having no cross-reacting IgA antibodies, the efficacy of cross-protection was not so high as that of nasal vaccination. These results suggest that the nasal inoculation of trivalent vaccines with CTB provides cross-protection against a broader range of viruses than does the current parenteral vaccination.

Administration, Intranasal↗

PubMed1992

[Transcatheter embolization for huge pulmonary arteriovenous fistula using metallic "spider" and spring embolus--application of hand-made metallic "spider" using partial monorail technique].

We performed transcatheter embolization in two cases with huge pulmonary arteriovenous fistula (AVF) using a metallic "spider" and spring embolus. Conventional spring embolus or detachable balloon could not be used in these cases. Metallic spider was indicated for pulmonary AVF with a feeding artery diameter of more than 16 mm to prevent embolus passing through the AVF. In the first case, we used large handmade metallic spiders of 25 mm in diameter followed by embolization by numerous spring coils. At that time, a partial monorail technique was newly devised to carry the large metallic spider into the feeding artery, otherwise the spider could not pass into a 9F catheter. After embolization, symptoms and PaO2 in arterial blood improved remarkably in both cases. In the second case, a spring coil migrated into the normal pulmonary artery, but no infarction resulted. In conclusion, the metallic spider was very useful for embolization of hugee pulmonary AVF to avoid the embolus passing through and to tangle spring coils together with it. If commercially available "spiders" are too small, ones can be made easily.

Adult↗

PubMed1992

Trigeminal nerve endings of lingual mucosa and musculature of the rat.

Horseradish peroxidase conjugated with wheat germ agglutinin (HRP-WGA) was injected into the trigeminal ganglion of adult rats to label the peripheral sensory receptors of the tongue. The conjugate was transported anterogradely to all the ipsilateral fungiform papillae and filiform papillae. Some labeled fibers crossed over to the contralateral papillae. In the intrinsic tongue muscle undulating nerve fibers along or across muscle fibers were often observed, and formed simple spiral endings.

Animals↗

PubMed1992

Chondroitin sulfate in the extracellular matrix of the medial and lateral superior olivary nuclei in the dog.

Chondroitin sulfate was examined in the extracellular matrix of the canine medial and lateral superior olivary nuclei by light and electron microscopic immunocytochemistry. The extracellular matrix around the large neurons was intensely stained with a monoclonal antibody recognizing D-glucuronic acid 2-sulfate----N-acetylgalactosamine 6-sulfate (D-unit) and this staining degree was remarkably reduced after chondroitinase ABC digestion. Neuronal cytoplasm, glial cells or capillaries in these nuclei were not stained with the monoclonal antibody. The results indicate the presence of disaccharide residue of D-glucuronic acid 2-sulfate----N-acetylgalactosamine 6-sulfate in the chondroitin sulfate proteoglycan of the extracellular matrix.

Animals↗

PubMed1992

EBV increases phosphoinositide kinase activities in human B cells.

To determine whether EBV affects phosphoinositide kinase activities of human B cells, we compared the activities between EBV- and EBV+ human B cell lymphoma lines. The two types of human B cells contained both phosphatidylinositol (PtdIns) 4-kinase and phosphatidylinositol 4-phosphate (PtdIns(4)P) kinase activities irrespective of the presence of EBV. However, both activities were increased in EBV+ cells compared to EBV- cells. The increases were associated with neither altered Km values for substrates nor altered elution profiles in DEAE-cellulose chromatography. Furthermore, expression of a latent EBV protein, EBV nuclear Ag1 (EBNA1) in BHK cells by the transfection of EBNA1 DNA was accompanied by increased PtdIns 4-kinase and PtdIns(4)P kinase activities. These increases also were not associated with altered Km values for substrates. However, phospholipase C activity was altered in neither EBV+ cells nor in EBNA1-expressing cells. These results indicate that EBV selectively increases the two phosphoinositide kinase activities in human B cells, although the viral gene product has no intrinsic phosphoinositide kinase activity. PtdIns 4-kinase and PtdIns(4)P kinase cooperatively synthesize PtdIns 4,5-bisphosphate, the major source of 1,2-diacylglycerol and inositol 1,4,5-triphosphate, the two second messengers in transducing signals for cell activation. Such increase therefore may play a role in EBV-induced human B cell activation.

1-Phosphatidylinositol 4-Kinase↗

PubMed1992

The response of the 5-hydroxyindole oxidation current to noxious stimuli in the spinal cord of anesthetized rats: modification by morphine.

The effects of cutaneous noxious heating and of systemic morphine on serotonergic activity in the spinal cord were examined in anesthetized rats. An oxidation current of 5-hydroxyindole signal was seen at 280-300 mV with differential normal pulse voltammetry. Noxious heat stimuli produced a mean signal increase over control values of 15.5 +/- 3.4% at 52 degrees C, and 7.2 +/- 5.5% at 45 degrees C. These increases lasted for 5-10 min. Non-noxious stimuli (37 degrees C) did not affect the 5-hydroxyindole signal. Morphine (0.5, 2.0 and 5.0 mg/kg, i.p.) in the absence of cutaneous stimulation did not change the signal significantly. Systemic morphine alone did not significantly modify the 5-hydroxytryptamine (5-HT) metabolism, as observed in in vivo voltammetry, in the spinal cord of anesthetized rat. However, a low dose of morphine (0.5 mg/kg, i.p.) attenuated the increase in the signal modified by noxious stimuli, and high doses (2.0 or 5.0 mg/kg, i.p.) enhanced it. Both effects of morphine were antagonized by naloxone (0.5 mg/kg, i.v.). It is likely that morphine with noxious stimuli modify the sensitivity of serotonergic descending inhibitory system. It is concluded that noxious heating of the skin increases the 5-HT metabolism in the spinal cord of anesthetized rats and that systemic administration of morphine modulates this 5-HT metabolism.

Analysis of Variance↗

PubMed1992

Elevation of metallothionein gene expression associated with hepatic copper accumulation in Long-Evans Cinnamon mutant rat.

The mechanism of the metallothionein (MT) gene expression was investigated in a mutant rat, LEC, which exhibits an abnormal accumulation of copper in hepatocytes. The levels of MT mRNA were extremely high and correlated with the hepatic copper concentrations in LEC rat liver. Gel retardation assays in nuclear extracts from LEC rat liver showed an increase in the copper-dependent binding proteins, which bind to the metal responsive element (MRE) of the MT gene. These results suggest that the high intracellular copper accumulation results in the elevation of the MT gene expression through increasing a putative trans-activating factor in LEC rat.

Aging↗

PubMed1992

Activation of calpain I in thrombin-stimulated platelets is regulated by the initial elevation of the cytosolic Ca2+ concentration.

The source and concentration of Ca2+ required to activate calpain I were investigated in thrombin-stimulated platelets. The concentration of cytosolic free Ca2+ ([Ca2+]i) was measured in platelets containing fura-2-AM, and exhibited a biphasic response after stimulation with 0.05, 0.1 or 0.5 NIH units of thrombin/ml. An initial transient elevation, which was predominantly dependent upon Ca2+ released from the internal stores into the cytosol, peaked at 15 s after stimulation, and a secondary sustained elevation, which was due to Ca2+ influx, was observed following the initial elevation. Calpain I was present at about 540 ng/10(8) unstimulated platelets, as measured by immunoblotting using rabbit anti-(human calpain I) IgG. Calpain I was activated 10 s after thrombin stimulation, as determined by the appearance of the 78 kDa and 76 kDa forms on immunoblots. The activation ratio of calpain I was calculated as the amount of the 78 + 76 kDa forms as a percentage of the total (80 + 78 + 76 kDa), and was influenced by the extent of the initial transient [Ca2+]i elevation after stimulation. An initial increase in [Ca2+]i of 300 nM was required to achieve the maximal activation (60%) of calpain I, and half-maximal activation occurred at 160 nM- Ca2+]i. These results suggest that the activation of calpain I in platelets is regulated by the initial elevation in Ca2+]i after thrombin stimulation, and does not necessarily require a Ca2+ influx.

Adult↗

PubMed1992

[New puncture technique for TIPSS (transjugular intrahepatic portosystemic stent shunt)].

To establish a safer puncture method for TIPSS (Transjugular Intrahepatic Portosystemic Stent Shunt), we developed a new percutaneous puncture technique to penetrate portal and hepatic vein trans-hepatically under ultrasonography (US technique). Experimentally we compared this technique with conventional transjugular technique puncturing portal vein through hepatic vein using Ross needle (Ross Needle technique). Success rate is 100% in US technique and 50% in Ross needle technique. Seven complication including intraperitoneal bleeding occurred in Ross needle technique, but no complication in US technique. Conclusively, US technique is a safer and more reliable method than that using Ross needle in the puncture method for TIPSS.

Animals↗