Biomedical subjects

S Mochizuki

Publications and source records attributed to S Mochizuki.

At least 109 records · Page 6Linked to original sources

PubMed1995

Quantitative analysis of IgA-subclass antibodies against tetanus toxoid.

Sera were analysed for levels of IgA- and IgG-class and IgA-subclass antibodies against tetanus toxoid and synthesized, tetanus-toxoid, beta-chain peptides. Forty-five peptides, deduced from the amino-acid sequence of the tetanus-toxoid beta-chain, were synthesized, in order to analyse epitope-binding of antibodies. Monoclonal, human, anti-tetanus antibodies were used to evaluate the synthesized peptides. Five synthesized peptides, bound by high, medium or low levels of IgA antibodies, were selected for the quantification of IgA1 and IgA2 antibodies. A set of chimeric, IgA-subclass antibodies with NP-specificity were used to quantify the antigen-specific IgA-subclass antibodies in a novel assay. Antibodies against the synthesized peptides were predominantly of IgA1 subclass.

Adult↗

PubMed1995

Molecular biological and quantitative abnormalities of ADP/ATP carrier protein in cardiomyopathic hamsters.

The adenine nucleotide translocator or ADP/ATP carrier protein (AAC) is an integral protein present in the inner mitochondrial membrane, which performs the exchange of cytoplasmic and intramitochondrial ADP and ATP. The myocardial AAC content was studied in J-2-N cardiomyopathic hamsters. The AAC content was found to be significantly decreased in J-2-N hamsters. For molecular biological analysis, hamster AAC (T1 isoenzyme) cDNA was cloned by the plaque hybridization method. This AAC cDNA hybridized specifically with AAC mRNA, so RNA dot-blot hybridization was performed. The highest AAC mRNA level was observed in control hamsters followed by J-2-N hamsters with mild myocardial damage, J-2-N hamsters with severe myocardial damage and Bio 14-6 cardiomyopathic hamsters. These results suggest that a decreased AAC content may contribute to the pathogenesis of cardiomyopathy and that a decrease of AAC mRNA levels may explain the abnormalities of AAC in J-2-N cardiomyopathic hamsters.

Animals↗

PubMed1995

Pharmacological properties of KT3-671, a novel nonpeptide angiotensin II receptor antagonist.

We examined pharmacological profiles of KT3-671, 2-propyl-8-oxo-1-[(2'-(1H-tetrazole-5-yl) biphenyl-4-yl)methyl]- 4,5,6,7-tetrahydro-cycloheptimidazole, a newly synthesized nonpeptide angiotensin II (AII) receptor antagonist in various in vitro and in vivo studies. KT3-671 displaced specific binding of [125I]Sar1 Ile8-AII to AT1 receptor with a Ki value of 0.71 +/- 0.14 x 10(-9) M in rat liver membranes, but had no affinity for AT2 receptor in bovine cerebellar membranes (Ki > 10(-5) M). In isolated rabbit aorta, KT3-671 produced a parallel rightward shift in the concentration-response curve for AII with a pA2 value of 10.04 +/- 0.12, but had no effect on KCl-, norepinephrine (NE)-, and serotonin (5-HT)-induced contractions. In conscious normotensive rats, KT3-671 (0.3-10 mg/kg, p.o.) inhibited the AII-induced pressor response dose dependently. In renal artery-ligated hypertensive rats, KT3-671 (0.1-3 mg/kg, p.o.) decreased arterial blood pressure (BP) dose dependently. The hypotensive action of 3 mg/kg KT3-671 was maintained for at least 24 h. These results suggest that KT3-671 is a potent AT1 subtype-selective and competitive nonpeptide AII receptor antagonist and has an orally active antihypertensive effect without agonistic activity.

Angiotensin II↗

PubMed1995

Antihypertensive effect of chronic KT3-671, a structurally new nonpeptide angiotensin AT1-receptor antagonist, in stroke-prone spontaneously hypertensive rats.

KT3-671 (2-propyl-8-oxo-1-[(2'-(1H-tetrazole-5-yl)biphenyl-4-yl)methyl]-4,5,6, 7-tetrahydrocycloheptimidazole), a structurally new nonpeptide angiotensin AT1-receptor antagonist, was administered orally and repeatedly to 15-week-old stroke-prone spontaneously hypertensive rats for 7 weeks; and its effects on blood pressure, heart rate, renal function, plasma renin concentration (PRC), plasma aldosterone concentration (PAC) and hypertension-related tissue damage in the brain, heart, kidney and mesenteric artery were investigated. KT3-671 at a dose of 3 or 10 mg/kg, p.o. per day prevented development of hypertension and produced a significant and consistent reduction of blood pressure in a dose-dependent manner. Enalapril at a dose of 10 mg/kg per day produced cardiovascular effects similar to those of KT3-671 at 10 mg/kg. Despite marked reduction in blood pressure, neither KT3-671 nor enalapril affected the heart rate. KT3-671 at 10 mg/kg produced a transient and significant reduction of urinary sodium excretion in the second week, but did not affect renal function at any other time during the experimental period. Both KT3-671 at 10 mg/kg and enalapril at 10 mg/kg produced a significant increase in PRC and showed a tendency to decrease PAC. Repeated administration of KT3-671 reduced the severity of the pathological changes in the kidney. These results suggest that KT3-671 is a potentially useful antihypertensive drug.

Aldosterone↗

PubMed1995

V-onc mutation associated with host cell growth in retroviral tumors.

In sarcomagenesis in rats infected neonatally with feline sarcoma virus (ST-FeSV), v-fes product (P85) was previously shown by us to be a predictive and preventive determinant. In order to explore the part played by P85 in tumor suppression, DNA was extracted from precancerous granulomas and from slow or rapid growing sarcomas induced by neonatal injection of the virus. The v-fes signal from extracted DNA was analyzed by PCR-SSCP. The prototype v-fes gene signal was detected in most lesions and found to be generally amplified in rapid growing sarcomas and in some granulomas. Several v-fes homologs showing varying mobilities in gel were seen in most sarcomas and some granulomas with or without the prototype v-fes signal. In slow growing sarcomas and granulomas induced in hosts that were immunized with ST-FeSV induced syngeneic sarcoma and proved to carry IgG antibody to P85, the prototype v-fes gene was found to be down-regulated and v-fes homologs were found to be reduced in number or eliminated. These results suggest that the development of v-fes mutations is associated with the growth potential of cells carrying the v-fes gene, and that host immunity to v-onc product influences the development of virogene rearrangements and results in slow and suppressed growth of tumors caused by neonatal infection with retrovirus.

Animals↗

PubMed1995

Molecular cloning of human 5-hydroxytryptamine3 receptor: heterogeneity in distribution and function among species.

The 5-hydroxytryptamine3 receptor 5-HT3R has been implicated in gut and cardiac motility and in behavioral disorders. Characteristics of 5-HT3Rs appear to be heterogeneous among species, but human 5-HT3R cDNA has not been identified. We isolated a cDNA encoding 5-HT3R from human hippocampus. The mouse 5-HT3R gene has been reported to generate two alternative splicing isoforms that differ by six amino acids. All of our isolated human clones corresponded to the shorter isoform. Amino acid identities with mouse neuroblastoma N1E-115 and rat brain 5-HT3Rs were 84% for each. Southern blot analysis of human genomic DNA suggested that our cloned transcript encoded a human counterpart for the rodent 5-HT3Rs. This gene was assigned to chromosome 11 using polymerase chain reaction analysis of a human/rodent somatic cell hybrid panel. With the use of Northern blot analysis, 5-HT3R transcripts were identified in human small intestine, colon, and brain regions including hippocampus, amygdala, and striatum. In human heart, 5-HT3R expression was not detectable even with reverse transcriptase-polymerase chain reaction analysis, although it was detectable in mouse heart. Transfection of COS-1 with human 5-HT3R cDNA induced specific binding of the 5-HT3R-selective radioligand [3H]YM060. Human 5-HT3R showed typical characteristics of the 5-HT3R, but its affinity for the 5-HT3R agonist m-chlorophenylbiguanide was much lower than that of rat 5-HT3R. When injected with human 5-HT3R cRNA, the oocytes responded to 5-HT3R agonists with a rapidly developing inward current. The potency of the agonists to induce inward current paralleled that to compete with the radioligand binding, and 2-methyl-5-hydroxytryptamine, a partial agonist for mouse 5-HT3R, was a full agonist for human 5-HT3R. Our data revealed that the 5-HT3R molecule has interspecies differences in both tissue distribution and functional profile.

Amino Acid Sequence↗

PubMed1994

Molecular cloning and functional expression of a cDNA encoding the human V1b vasopressin receptor.

Arginine vasopressin modulates the release of adrenocorticotropic hormone, beta-endorphin, and prolactin from the anterior pituitary. Release is mediated by the V1b receptor through the mobilization of intracellular Ca2+ by phosphatidylinositol hydrolysis. In contrast to its well characterized peripheral actions, such as antidiuresis, contraction of vascular smooth muscle, and stimulation of hepatic glycogenolysis, the exact site and mechanism of vasopressin action in the pituitary remain unclear. This is largely due to a lack of information on the molecular identity and exact localization of the V1b receptor. This lack prompted us to try to isolate this receptor subtype. Here we report the molecular cloning and functional expression of a complementary DNA encoding the human V1b receptor. The deduced 424-amino acid sequence of the receptor has highest overall homology with the V1a, V2, and oxytocin receptors, with homologies of 45, 39, and 45%, respectively. The receptor expressed in COS-1 cells has a single binding site for arginine vasopressin with a Kd of 0.17 +/- 0.04 nM. It binds various agonists and antagonists of vasopressin with affinities distinct from those of V1a and V2 receptors but consistent with those anticipated for the V1b receptor on the basis of the pharmacological studies. Furthermore, arginine vasopressin evoked calcium-dependent chloride current in Xenopus oocytes transfected with the receptor, which was not affected by a V1a/V2 antagonist. In contrast, the current evoked in oocytes transfected with V1a receptor was abolished by the antagonist. Northern blot analysis revealed that the receptor expression is restricted to the pituitary. These data clearly indicate that the cloned cDNA encodes the V1b receptor.

Amino Acid Sequence↗

PubMed1994

Relationship between calcium permeability and rectification properties of AMPA receptors in cultured rat hippocampal neurons.

Cultured rat hippocampal neurons were classified into three groups on the basis of the functional properties of their AMPA-subtype glutamate receptors. The type I neuron had AMPA receptors with an outwardly rectifying I-V relation and little permeability to Ca2+ whereas the AMPA receptors in the type II neuron were characterized by marked inward rectification and high Ca2+ permeability. In the third type of neuron, the responses of AMPA receptors exhibited intermediate properties in both I-V relation and Ca2+ permeability. We suggest that these intermediate properties in the third type of neuron reflect the coexistence of Ca(2+)-permeant and Ca(2+)-impermeant AMPA receptors.

Animals↗

PubMed1994

Characterization of cloned human cholecystokinin-B receptor as a gastrin receptor.

The cholecystokinin (CCK)-B receptor cloned from human brain was characterized as a gastrin receptor by using heterologous expression systems of COS-7 cells and Xenopus oocytes. 125I-gastrin binding to human CCK-B receptor expressed in COS-7 was time-dependent, saturable and also specific, as well as 125-I-CCK-8. The binding of 125I-gastrin was inhibited by CCK-8 about 10-fold more potently than by gastrin. The rank order of potency of several antagonists to 125I-gastrin binding was YM022 > CI-988 > L-365,260 > L-364,718. Addition of GTP gamma S, a nonhydrolysable analog of GTP, dose-dependently inhibited 125I-gastrin binding, and lowered the gastrin binding affinity, Gastrin (10(-9)-10(-7) M) also evoked a Ca(2+)-dependent Cl- current in Xenopus oocytes expressing CCK-B receptors. These results suggest that the pharmacological profile of the cloned human CCK-B receptor using 125I-gastrin is closely parallel to that reported in gastric mucosa, and that the receptor transduces cellular signals of gastrin as well as those of CCK-8.

Amino Acid Sequence↗

PubMed1994

An autopsy case of pseudosarcoma of the common bile duct.

An autopsy case of pseudosarcoma in the common bile duct is reported. An 82-year-old Japanese male complaining of jaundice was admitted to our hospital; he was examined by abdominal ultrasonography (US), revealing biliary calculus, dilatation of the common bile duct, and choledocholithiasis, considered to be the possible cause of the obstructive jaundice. Endoscopic retrograde biliary drainage (ERBD) and cholangioscopy were performed concurrently, revealing a vaguely whitish tumor near the papilla of Vater. Two months later, the patient died from complications of the liver, infection, and disseminated intravascular coagulation (DIC). An autopsy study revealed tumor cells with extreme pleomorphic changes, growing diffusely, very like sarcoma. Further examination revealed epithelioid arrangements in the metastatic lymph node. Twelve kinds of immunohistochemical examination showed a positive reaction, reflecting the presence of an epithelioid cytoskeleton. Of 28 cases of true and pseudosarcoma of the biliary system reported in the Japanese literature, only 1 case was reported, in 1990, to involve the common bile duct. We therefore report the present case of pseudosarcoma of the common bile duct.

Aged↗

PubMed1994

Ion permeation properties of the cloned mouse epsilon 2/zeta 1 NMDA receptor channel.

The heteromeric mouse epsilon 2/zeta 1 N-methyl-D-aspartate (NMDA) receptor was expressed in Xenopus oocytes, and its channel properties were studied using both the outside-out patch-clamp and two-microelectrode voltage-clamp techniques. In the cloned receptor channel, permeation properties of monovalent and divalent cations, and voltage-dependent block by Mg2+ were similar to those reported previously in the native NMDA receptor channels. The sequence of single-channel conductances for alkali metals was Rb+ > Cs+ approximately K+ > Na+ > Li+, whereas the sequence of relative permeabilities was Cs+ > Rb+ > K+ approximately Na+ > Li+. The single-channel conductances measured in isotonic Ca2+, Sr2+ and Ba2+ solutions were almost equal, and approximately one-fifth of the value in the Na+ solution, although the permeabilities for these alkaline earth cations were higher than for Na+. It is likely that Ca2+, Sr2+ and Ba2+ would enter the NMDA receptor channel more easily than Na+, but would bind to a site in the channel more tightly, the net effect being a reduced value of the current.

Animals↗

PubMed1994

Effect of lemakalim on action potentials, intracellular calcium, and contraction in guinea pig and human cardiac myocytes.

OBJECTIVE: The aim was to investigate the effects of lemakalim on action potential duration, intracellular free calcium ([free Ca2+]i), and cell contraction in human and guinea pig cardiac myocytes. In addition, the possible modulation by pH of lemakalim induced activation of ATP sensitive potassium (KATP) channels was assessed. METHODS: Single ventricular myocytes were enzymatically dissociated from adult male guinea pigs (300-600 g). Single myocytes were isolated from human ventricular tissues. Cells were loaded with the acetoxymethyl ester form of fura-2 to monitor changes in [free Ca2+]i and subjected to conventional electrophysiological techniques. RESULTS: In guinea pig cells, lemakalim (3, 10, 30 microM) reduced action potential duration in a concentration dependent manner. This decrease was accompanied by hyperpolarisation of the resting membrane potential. Lemakalim (3, 10, 30 microM) reduced the systolic fura-2 fluorescence ratio without having a significant effect on diastolic fluorescence and also reduced the cell contraction in concentration dependent manner. Glibenclamide (1 microM), a specific inhibitor of KATP channels, did not affect action potential duration, fura-2 fluorescence ratio, or cell contraction in the absence of lemakalim. However, the same dose of glibenclamide markedly inhibited the lemakalim induced decrease in action potential duration, fura-2 fluorescence ratio, and cell contraction. Reducing extracellular pH enhanced the decrease in action potential duration induced by lemakalim. In human ventricular myocytes, lemakalim (3, 10 and 30 microM) caused a decrease in action potential duration and systolic fura-2 fluorescence ratio. The reduction in action potential duration and fura-2 fluorescence ratio was also reversed by glibenclamide (1 microM). CONCLUSIONS: These results suggest that lemakalim reduces systolic [free Ca2+]i by activating ATP sensitive potassium channels which results in a decrease of action potential duration in guinea pig and human ventricular myocytes. The reduction in [free Ca2+]i mediates the negative inotropic effect induced by lemakalim. In addition, pH may modulate the KATP channel activation by the channel opener.

Action Potentials↗

PubMed1994

Nonpeptide angiotensin II receptor antagonists. I. Synthesis and biological activity of pyridine derivatives.

Substituted pyridines were synthesized as potential angiotensin II (AII) receptor antagonists. Substitution at the position 2 in the pyridine resulted in potent activity, and the optimal alkyl length was four carbons. The potency further increased with the introduction of a hydroxymethyl group at the position 4. One of the compounds, 2-butyl-6-chloro-4-hydroxymethyl-5-methyl-3-[[2'-(1H-tetrazol-5-yl )biphenyl-4-yl]methyl]pyridine 9 h (KT3-579) is a competitive AII antagonist with a pA2 value of 9.31, and is about 10 times more potent than Du Pont 753. It was found to be an AT1 specific antagonist with an IC50 of 3.09 nM.

Angiotensin Receptor Antagonists↗

PubMed1994

Multistep alterations of human lymphocytes infected with HTLV-I and then exposed to carcinogens.

Normal human lymphocytes achieved continuous growth in IL-2-containing medium in vitro following HTLV-I infection. They showed specific structural abnormalities of certain chromosomes. Subsequent to exposure to MNNG and TPA, or to UV, they achieved autonomous growth (transformation). Alterations in the signal transduction system were observed in transformed cells that showed loss of ability to grow in the medium containing TPA. Additional chromosome abnormalities appeared in transformed cells. These abnormalities were found to cluster to chromosomes that had preexisting structural abnormalities. Changes of the met gene on chromosome 7, to which structural abnormalities were observed clustering, were detected by Southern blot analysis. Environmental carcinogens may work as cofactors to promote transformation of human lymphocytes infected with HTLV-I. The initial change of human lymphocytes caused by HTLV-I integration may be advanced toward neoplastic transformation by their exposure to other carcinogens.

Carcinogens↗

PubMed1994

Genetic instability of human cells with DNA related to human retrovirus.

To elucidate the role of HTLV-I in human neoplasia, DNA was extracted from tumor tissues, cultured cells, and/or sera from 20 HTLV-I seropositive and from 10 seronegative cancer patients, subjected to PCR-PAGE, and analyzed by Southern hybridization. HTLV-I related sequences were detected in tumors of the seropositives with different types of cancer. In the seronegatives, gag related sequences were detected in some tumors, whereas LTR related sequences were detected in only uterus carcinoma and tax related sequences in none of tumors examined. These sequences were detected in tumor cells as well as lymphoid cells by in situ hybridization. Some of these sequences were also detected in cultured fibroblasts derived from ATL patients. Cultured normal human lymphocytes grew continuously in conditioned media following HTLV-I infection, and transformed on exposure to carcinogens. Chromosome changes in transformed cells appeared clustering to chromosomes abnormalized on HTLV-I infection. The frequency of abnormal chromosomes in lymphocytes was significantly higher in the seropositives and in their family members than in seronegative normal donors. The frequency increased with advancement of host age in the seropositives but not in the seronegatives. These findings indicate that some individuals carry HTLV-I related sequences that may be derepressed by host aging and resulted in increasing genetic instability of host cells rendering them increasingly susceptible to carcinogens.

Adult↗

PubMed1994

Suppression of retroviral tumors in hosts immune to viral oncogene product.

Feline sarcoma virus of Snyder-Theilen strain (ST-FeSV) induces sarcomas in Wistar/Ma rats following neonatal virus injection. Induced tumors express the viral oncogene product (P85) and elicit in hosts the specific serum anti-P85 antibody detectable by Western blot analysis. Syngeneic adult female rats were immunized with an ST-FeSV induced sarcoma that was 100% transplantable to syngeneic adult rats. Newborns from immunized rats (vaccinated rats) were found to carry anti-P85 in their sera at birth. Following neonatal injection of the virus to vaccinated and non-vaccinated control rats, tumor incidence was found to be lower and survival time significantly longer in vaccinated rats than in controls (p < 0.01). A nonapeptide known to be thymic hormone (FTS) showed suppressive effects on tumor development. These results indicate that tumors caused by perinatal retrovirus infection may be suppressed by efficient elicitation of cell-mediated immune response against the product of oncogene of the causative virus.

Amino Acid Sequence↗

PubMed1993

Na+/H+ exchanger and reperfusion-induced ventricular arrhythmias in isolated perfused heart: possible role of amiloride.

The roles of the Na+/H+ exchange system in the development and cessation of reperfusion induced ventricular arrhythmias were studied in the isolated perfused rat heart. The hearts were perfused in the working heart mode with modified Krebs Henseleit bicarbonate (KHB) buffer and whole heart ischemia was induced by a one-way ball valve with 330 beat/min pacing. Ischemia was continued for 15 min followed by 20 min of aerobic reperfusion (control). Amiloride (1.0 mM), an inhibitor of the Na+/H+ exchange system, was added to the KHB buffer only during reperfusion (group B) or only during ischemic periods (group C). Electrocardiographic and hemodynamic parameters were monitored throughout the perfusion. Coronary effluent was collected through pulmonary artery cannulation and PO2, PCO2, HCO3- and pH were measured by blood-gas analyzer. The incidence of reperfusion induced ventricular arrhythmias was 100%, 100% and 0% in control, group B and group C, respectively. The mean onset time of termination of reperfusion arrhythmias was significantly shorter in group B than in control. PCO2 increased from 39.0 +/- 0.9 to 89.3 +/- 6.0 mmHg at the end of ischemia in control and from 40.6 +/- 0.4 to 60.5 +/- 5.8 in group C, the difference between groups was statistically significant. HCO3- level decreased from 21.8 +/- 0.1 to 18.3 +/- 0.5 mmol/l in control, however, this decrease was significantly inhibited in group C (from 22.0 +/- 0.5 to 20.3 +/- 0.2). The increase in PCO2 and the decrease in HCO3- in group B were similar over time to those observed in control.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiloride↗

PubMed1993

Pharmacologic properties of KT2-962 (6-isopropyl-3-[4-(p- chlorobenzenesulfonylamino)-butyl]-azulene-1-sulfonic acid sodium salt); a new TXA2/prostaglandin endoperoxide receptor antagonist.

Pharmacologic properties of KT2-962 (6-isopropyl-3-[4-(p-chlorobenzenesulfonylamino)butyl]-azulene+ ++-1-sulfonic acid sodium salt, KT) were studied in isolated rat aorta, rat tail artery, rabbit aorta, rabbit renal artery, and pig coronary artery. KT competitively inhibited the contractions induced by thromboxane A2 (TXA2) mimetic, U46619 (pA2 values 9.95, 8.85, 7.87, 8.49, and 9.12, respectively). KT also inhibited the contraction of rabbit aorta induced by prostaglandin2 alpha (PGF2 alpha, pA2 value 7.85) and the contraction of guinea pig ileum induced by LTD4 (pA2 value 5.48) but did not alter the contractions induced by norepinephrine (NE), Ca2+, serotonin, and histamine. KT did not alter the contractions of guinea pig ileum, which did not contract with U46619, induced by PGE2 and PGF2 alpha. KT inhibited the aggregations of rabbit platelets induced by U46619, arachidonic acid, and collagen (IC50 values 7.9, 140, and 16 microM, respectively) but not those induced by ADP. It also inhibited the specific binding of TXA2/PGH2 receptor antagonist, [3H]SQ29,548, to rabbit gel-filtered platelets with an IC50 value of 1.5 x 10(-8) M. In in vivo experiments with mice, oral administration of KT protected the U46619-induced sudden death with the minimum effective dose of 0.3 mg/kg and provided such protection for > 8 h at 1.0 mg/kg. These results indicate that KT is a new nonprostanoid type TXA2/PGH2 receptor antagonist that is orally effective and long acting.

Animals↗