1601
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Yoshioka M, Narai N, Shinkai A, Tokuda T, Saito K, Shioya M, Tokoro N, Kono Y. Analyses of metal ions in spider venoms in relation to insecticidal activity of clavamine. Biol Pharm Bull 1994; 17:472-5. [PMID: 8069250 DOI: 10.1248/bpb.17.472] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
To elucidate insecticidal activity of spider toxins, metal ions in venoms and in the bodies were determined by thin layer chromatography, spark source mass spectrometry, ion chromatography, inductively coupled plasma emission spectrometry and atomic absorption spectrometry. Two kinds of spiders were used, Nephila clavata and Nephila maculata. Metals from their venom glands were extracted with hydrochloric acid and the metal concentrations were almost the same in the two species. Many kinds of metals, Fe, Zn, Pb, Cu, Ca, Mg, Na, P and S were found at higher levels in the venoms at concentrations higher than in the bodies. The contents of metal ions were low in the dragonfly and the cicada which are considered to be preys. Clavamine, the main insecticidal component in N. clavata, was effective on larvae of a mosquito with Ca2+, Fe3+ or Pb2+, but ineffective with Mg2+, Zn2+, Fe2+ or Cu2+. It is suggested that the metal chelates play an important role in the intoxication and detoxication of the spider toxins.
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1602
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Nakayama R, Kumagai H, Saito K. Evidence for production of platelet-activating factor by yeast Saccharomyces cerevisiae cells. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1199:137-42. [PMID: 8123662 DOI: 10.1016/0304-4165(94)90108-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Various yeast strains were screened for platelet-activating factor (PAF) production. High PAF production was found mainly in the strains of Saccharomyces genus. Yeast PAF showed a typical platelet aggregation pattern, which was inhibited by specific PAF antagonists, such as CV-3988, CV-6209 and L-652731. The main molecular species of yeast PAF were identified as 1-palmitoleoyl-, -palmitoyl-, -oleoyl- and -stearoyl-2-acetyl-sn-glycero-3-phosphocholines (16:1, 16:0, 18:1 and 18:0 acylPAFs) and 1-hexadecenyl- and hexadecyl-2-acetyl-sn-glycero-3-phosphocholines (16:1 and 16:0 PAFs), by mass spectrometry. PAF formation in yeast cells increased at the middle stationary phase of growth.
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1603
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Kanoh T, Saito K, Matsunaga K, Oguchi Y, Taniguchi N, Endoh H, Yoshimura M, Fujii T, Yoshikumi C. Enhancement of the antitumor effect by the concurrent use of a monoclonal antibody and the protein-bound polysaccharide PSK in mice bearing a human cancer cell line. In Vivo 1994; 8:241-5. [PMID: 7919129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The antitumor effects of a monoclonal antibody against a human cancer cell line and a protein-bound polysaccharide, PSK, obtained from cultured mycelia of Coriolus versicolor in basidiomycetes were examined. The IgG2a monoclonal antibody against the human colon cancer cell line colo 205 induced in vitro antibody-dependent macrophage-mediated cytotoxicity against the cancer cells, but only slightly suppressed the in vivo growth of the cancer cells. Concurrent use of PSK with the antibody enhanced the in vitro antibody-dependent macrophage-mediated cytotoxicity as well as the in vivo antitumor activity. These findings suggest that the combined use of a monoclonal antibody and PSK, which have different modes of action, may be useful in the treatment of cancer.
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1604
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Saito K, Furuta Y, Sano H, Yokoyama M, Fukuzaki H. Ambulatory blood pressure and heart rate during once-daily, randomized, crossover administration of carteolol and atenolol. Clin Ther 1994; 16:181-90. [PMID: 8062314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This study evaluated the effect of beta-adrenoceptor blocking agents (beta-blockers) with or without intrinsic sympathomimetic activity on the 24-hour blood pressure profile of 15 untreated patients with essential hypertension. After a 4-week run-in period, subjects were randomly assigned to an 8-week treatment period of once-daily carteolol (15 mg/d) or atenolol (50 mg/d). The groups were crossed over at week 8. Office blood pressure and heart rate were recorded every 2 weeks and 24-hour ambulatory blood pressure monitoring was performed immediately preceding and at the conclusion of each period. Both drugs significantly reduced (P < 0.01) office blood pressure and heart rate throughout the two treatment periods. The 24-hour ambulatory blood pressure monitoring at 0.5- and 1-hour intervals revealed that systolic blood pressure in 2 of 8 sleeping hours and diastolic blood pressure in 4 of 8 sleeping hours were significantly higher (P < 0.05) after carteolol treatment than after atenolol treatment. The average values for both daytime and nighttime blood pressures, however, were significantly lower at the end of both periods. Although atenolol lowered heart rate throughout the 24-hour period, there was a smaller reduction in heart rate with carteolol than with atenolol during daytime (-5.4 +/- 4.9 beats/min vs -12.7 +/- 6.6 beats/min, P < 0.005, respectively). Heart rate increased during nighttime (P < 0.02) and was significantly greater than with atenolol treatment (5.0 +/- 7.2 beats/min vs -5.7 +/- 8.0 beats/min, P < 0.001, respectively). These results suggest that the different effects of the two beta-blockers on heart rate and nighttime blood pressure may be attributed to the presence or absence of intrinsic sympathomimetic activity.
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1605
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Kanoh T, Matsunaga K, Saito K, Fujii T. Suppression of in vivo tumor-induced angiogenesis by the protein-bound polysaccharide PSK. In Vivo 1994; 8:247-50. [PMID: 7522606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The anti-angiogenic effects of an antitumor protein-bound polysaccharide, PSK, obtained from cultured mycelia of Coriolus versicolor in basidiomycetes were examined by the mouse dorsal air sac assay. PSK suppressed the mouse hepatoma MH134-induced angiogenesis when assessed by morphological and biochemical examinations. This finding suggested that the anti-metastatic effect of PSK is attributed to the suppression of tumor-induced angiogenesis.
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1606
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Funayama M, Kumagai T, Saito K, Watanabe T. Asphyxial death caused by postextraction hematoma. Am J Forensic Med Pathol 1994; 15:87-90. [PMID: 8166123 DOI: 10.1097/00000433-199403000-00018] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A 71-year-old man was admitted to an emergency room because of postextraction hemorrhage and died of asphyxia caused by airway obstruction. About 40 days earlier, he had had 11 carious teeth removed without postextraction bleeding. At autopsy, liver cirrhosis was found, but examination of his previous extractions and postmortem external findings did not show a general hemorrhagic tendency. The surgical incision in the gingiva had been sutured, and no damage to the bony socket or large vasculature was found. We could not determine the etiologic source of the decedent's rapidly increasing hematoma. Postextraction hemorrhage or hematoma is a common complication in routine dental extraction, but marked hematoma formation around the airway may cause critical respiratory problems in the short run. In such cases, the maintenance of the airway, including control of hemorrhage, is necessary at an early stage.
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1607
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Saito K, Aoki T, Aoki T, Yanagida T. Movement of single myosin filaments and myosin step size on an actin filament suspended in solution by a laser trap. Biophys J 1994; 66:769-77. [PMID: 8011909 PMCID: PMC1275775 DOI: 10.1016/s0006-3495(94)80853-7] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Movement of single myosin filaments, synthesized by copolymerization of intact myosin and fluorescently labeled light meromyosin, were observed along a single actin filament suspended in solution by a dual laser trap in a fluorescence microscope. The sliding velocity of the myosin filaments was 11.0 +/- 0.2 micron/s at 27 degrees C. This is similar to that of actin moving toward the center from the tip (the physiological direction) of myosin filaments bound to a glass surface but several times larger than that in the opposite direction (Ishijima and Yanagida, 1991; Yanagida, 1993). This indicates that the movement of myosin filaments is dominated by the myosin heads on one side of the myosin filament, which are correctly oriented relative to the actin filament. The incorrectly oriented myosin heads on the other side do not interfere with the fast movement. The step size (displacement produced during one ATPase cycle) of correctly oriented myosin was estimated from the minimum number of myosin heads necessary to produce the maximum velocity. This was determined by measuring the velocities of various lengths of myosin filaments. The minimum length of the myosin filaments moving near the maximum velocity was 0.30-0.40 microns, which contains 20 +/- 5 correctly oriented myosin heads. This number leads to a myosin step size of 71 +/- 22 nm. This value probably represents the lower limit, because all of the myosin heads on the filament would not always interact with the actin filament. Thus, the myosin step size is considerably larger than the length of a power stroke expected from the physical size of a myosin head, 10-20 nm (Huxley, 1957, 1969).
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1608
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Otsuji Y, Arima N, Fujiwara H, Saito K, Kisanuki A, Tanaka H. Reversible complete atrioventricular block due to malignant lymphoma. Eur Heart J 1994; 15:407-8. [PMID: 8013520 DOI: 10.1093/oxfordjournals.eurheartj.a060514] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
An 83-year-old man was hospitalized due to general fatigue and dyspnoea. He was diagnosed as having complete atrioventricular (AV) block due to cardiac involvement by a malignant lymphoma. Eleven days after the initiation of chemotherapy, the complete AV block disappeared and only a first degree AV block remained.
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1609
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Heyes MP, Saito K, Devinsky O, Nadi NS. Kynurenine pathway metabolites in cerebrospinal fluid and serum in complex partial seizures. Epilepsia 1994; 35:251-7. [PMID: 8156942 DOI: 10.1111/j.1528-1157.1994.tb02428.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The kynurenine pathway metabolites, quinolinic acid (QUIN) and L-kynurenine are convulsants, whereas kynurenic acid (KYNA) is an antagonist of excitatory amino acid receptors. Imbalances in the concentrations of these metabolites have been implicated in the etiology of human seizure disorders. In the present study, L-kynurenine and QUIN concentrations in both cerebrospinal fluid (CSF) and serum were reduced in patients with intractable complex partial seizures (CPS) in both the postictal period (15-75 min after a seizure) and the interictal period (absence of seizure for > 24 h) as compared with neurologically normal control subjects. Linear regression analyses and analysis of covariance showed that the reductions in serum QUIN and L-kynurenine were correlated to blood antiepileptic medication. L-Tryptophan (L-TRP) levels also tended to be lower in both CSF and serum of the seizure patients. CSF KYNA and serum 3-hydroxykynurenine concentrations were not affected in seizure patients, whereas serum levels of KYNA were reduced. 3-Hydroxykynurenine was not detected in the CSF of either control or seizure patients. The results do not support a role for a generalized reduction in KYNA concentrations or an increased ratio of QUIN:KYNA, or increases in CSF L-kynurenine in initiation and maintenance of intractable CPS humans.
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1610
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Kubo M, Nakaya Y, Matsuoka S, Saito K, Kuroda Y. Atrial natriuretic factor and isosorbide dinitrate modulate the gating of ATP-sensitive K+ channels in cultured vascular smooth muscle cells. Circ Res 1994; 74:471-6. [PMID: 8118955 DOI: 10.1161/01.res.74.3.471] [Citation(s) in RCA: 113] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The effects of atrial natriuretic factor (ANF) and isosorbide dinitrate (ISDN), activators of particulate and soluble guanylate cyclase, respectively, on K+ currents were investigated in patch-clamp recordings of smooth muscle cells cultured from rat thoracic aorta. In the cell-attached patch configuration, ANF enhanced Ca(2+)-activated K+ (KCa) channel activities as reported previously. When KCa channels were blocked with 1 mmol/L tetraethylammonium or 10(-7) mol/L charybdotoxin, ANF and ISDN applied to the bathing solution activated ATP-sensitive K+ (KATP) channels without altering channel conductance. Pretreatment with methylene blue, a guanylate cyclase inhibitor, abolished the effects of ISDN on KATP channels, whereas 8-bromo-cGMP activated these channels, suggesting that the effects of ISDN on KATP channels were mediated by cGMP. Our results suggest that vasorelaxant agents that increase intracellular cGMP concentrations modulate the gating of two major potassium channels, ATP sensitive and Ca2+ activated, that might play an important role in controlling vascular tone by changing the membrane potential.
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1611
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Kobayashi J, Saito K, Takahashi N, Kamiya I. Optical activity and birefringence of the incommensurate phase of Rb2ZnBr4. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:6539-6547. [PMID: 10009371 DOI: 10.1103/physrevb.49.6539] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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1612
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Horie M, Saito K, Nose N, Nakazawa H. Simultaneous determination of benofloxacin, danofloxacin, enrofloxacin and ofloxacin in chicken tissue by high-performance liquid chromatography. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1994; 653:69-76. [PMID: 8012562 DOI: 10.1016/0378-4347(93)e0428-s] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A simple, rapid and reliable high-performance liquid chromatographic (HPLC) method for the simultaneous determination of residual fluoroquinolones (benofloxacin, danofloxacin, enrofloxacin and ofloxacin) in chicken has been developed. The drugs were extracted with 0.2% metaphosphoric acid-acetonitrile (7:3, v/v), followed by a Bond Elut C18 clean-up procedure. The HPLC separation was carried out on a Wakosil II 5C18-HG column (150 x 4.6 mm I.D.) with 0.05 M phosphate buffer (pH 2.4)-acetonitrile (80:20, v/v) containing 2.5 mM 1-heptanesulfonic acid as the mobile phase. A fluorescence detector was used at an excitation wavelength of 295 nm and an emission wavelength of 455 nm. The calibration graphs were linear from 0.1 to 10 ng for danofloxacin and from 1 to 100 ng for benofloxacin, enrofloxacin and ofloxacin. The recoveries of the drugs from tissues fortified at a level of 0.2 microgram/g were 81.1-89.6%, and the detection limits were 0.01 microgram/g for ofloxacin, danofloxacin and enrofloxacin and 0.02 microgram/kg for benofloxacin. The time needed per sample was less than 60 min.
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1613
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Lin CM, Saito K, Tsujino T, Yokoyama M. Calcium supplementation inhibits the expression of parathyroid hypertensive factor in DOCA-salt hypertensive rats. Am J Hypertens 1994; 7:201-4. [PMID: 8179855 DOI: 10.1093/ajh/7.2.201] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
To elucidate the antihypertensive mechanism of oral calcium supplementation in salt-dependent hypertension, we investigated the hypertensive activity of plasma from DOCA-salt hypertensive rats fed with (DS-Ca) or without (DS) a high calcium diet. Four weeks of calcium supplementation (4% CaCl2) attenuated the blood pressure increase in DS rats. Intravenous bolus injection of dialyzed plasma (1.0-kDa cutoff) from DS rats to normotensive rats resulted in a sustained elevation in blood pressure, whereas that from DS-Ca rats did not. As the endothelin concentration was not different between the two groups, the circulating hypertensive substance in DS rats may be identical to parathyroid hypertensive factor (PHF) and the inhibition of its expression by calcium may be involved in the hypotensive mechanism of high calcium diets in salt-dependent hypertension.
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1614
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Shigemasa Y, Saito K, Sashiwa H, Saimoto H. Enzymatic degradation of chitins and partially deacetylated chitins. Int J Biol Macromol 1994; 16:43-9. [PMID: 8180144 DOI: 10.1016/0141-8130(94)90010-8] [Citation(s) in RCA: 139] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The enzymatic (lysozyme, chitinase etc.) digestibility of chitins obtained from squid pen and shrimp shell, and of partially deacetylated chitins (DA-chitins) was investigated. The digestibility of various chitins by the chitinase from Bacillus sp. PI-7S was much higher than that by lysozyme, and beta-chitin was digested more smoothly than alpha-chitin. DA-chitin deacetylated under homogeneous conditions (DAC) was hydrolysed by lysozyme more rapidly than that deacetylated under heterogeneous conditions (DAC). DACs from shrimp shell and squid pen showed the same degree of digestibility by lysozyme in spite of a difference in the crystal structure of the original chitins. The crystal structure of chitin and the degree of N-acetyl group aggregation among DA-chitin molecules affect the enzymatic digestibility of chitin and DA-chitin, respectively.
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1615
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Murata T, Soga T, Tajima K, Saito K, Komeda Y, Ioshii SO, Shiraishi T, Sakakura T, Yatani R. Sarcomatoid carcinoma of the urinary tract. Pathol Int 1994; 44:138-44. [PMID: 7517761 DOI: 10.1111/j.1440-1827.1994.tb01698.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Sarcomatoid carcinoma is a rare variant of malignant tumor arising from the urinary tract. This tumor had been termed carcinosarcoma because of its carcinomatous and sarcomatous components. There is still some confusion in the terminology between true carcinosarcoma and sarcomatoid carcinoma; however, the latter is now regarded as primarily a malignant epithelial tumor with pseudosarcomatous transformation. Four cases of sarcomatoid carcinoma arising from the urinary tract are reported. The patients were a 77 year old female, and three males aged 62, 69 and 80 years. All but the eldest patient complained of gross hematuria. Surgical removal was performed in the younger three cases, and an autopsy was done in the remaining case. All the tumors were macroscopically polypoid. Histopathologic examination revealed fasciculated spindle-cell tumors with myxoid stroma or malignant fibrous histiocytoma-like spindle cell tumors. The epithelial nature was proven in these sarcomatous cells by immunohistochemical and/or electron-microscopic examinations. Only a small amount of squamous cell carcinoma components was also evident in the latter three cases. Although the younger three patients were alive at 44, 23 and 39 months' follow-up, respectively, constant careful monitoring is recommended.
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1616
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Saito K, Suetsugu T, Oku Y, Kuroda A, Tanaka H. Alpha 1-adrenoceptors in the conduction system of rat hearts. Br J Pharmacol 1994; 111:465-8. [PMID: 8004391 PMCID: PMC1909963 DOI: 10.1111/j.1476-5381.1994.tb14759.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
1. We have characterized alpha 1-adrenoceptor in the conduction systems of the rat heart by quantitative autoradiography. 2. Consecutive 20 micron thick sections from a single rat heart containing the sinoatrial (SA) node and atrioventricular (AV) node were incubated with increasing concentrations of [3H]-prazosin with or without 10 microM phentolamine. After exposure to 3H-Ultrofilm, optical densities corresponding to the SA node and AV node were determined by computerized densitometry after comparison with 3H standards. 3. The SA node and AV node were stained heavily for cholinesterase and they contained a higher concentration of alpha 1-adrenoceptors than the adjacent myocardium without a significant change in the affinity. 4. These results support the hypothesis that alpha 1-adrenoceptors may play an important role not only in inotropism but also in chronotropism of rat hearts.
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1617
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Tsuji Y, Okuyama K, Kobayashi K, Shibata T, Saito K, Kitazawa K, Sugisaki T. [Studies on cell-mediated immunity (CMI) in the glomeruli: immunization with GBM antigen from Masugi nephritis in Wistar-Kyoto rats]. NIHON JINZO GAKKAI SHI 1994; 36:95-102. [PMID: 8139154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The role of cell-mediated immunity in glomerular injury has been extensively studied, but the precise mechanism remains obscure. This study was undertaken to determine whether the homologous glomerular basement membrane (GBM) combined heterogeneous anti-GBM antibody would induce cell-mediated immunity. Wistar-Kyoto rats were divided into three groups; group I rats were immunized with homologous GBM antigen that was derived from Masugi nephritis and emulsified in complete Freund's adjuvant (CFA); group II rats were immunized with homologous GBM antigen that was derived from normal rats and emulsified in CFA; group III rats were immunized with CFA only. Group I rats demonstrated proteinuria on days 7 and 10 after immunization. Histologically, mesangial cell proliferation and cell infiltration were observed in the glomeruli. No changes in tubulointerstitial tissue. CD4-positive cells, CD8-positive cells and macrophages were found in the glomeruli, and mononuclear cells were found in the glomerular capillary lumen. Group II and Group III rats demonstrated no proteinuria and no histological changes. These findings indicated that the altered GBM obtained antigenicity and induced cell-mediated immunity in the glomeruli.
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1618
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Haba T, Takahashi K, Kito C, Akashi N, Yamazaki Y, Saito K. [A case of Sjogren syndrome with renal tubular acidosis, osteomalacia and pseudo-bone fracture]. NIHON NAIKA GAKKAI ZASSHI. THE JOURNAL OF THE JAPANESE SOCIETY OF INTERNAL MEDICINE 1994; 83:127-9. [PMID: 9132440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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1619
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Saito K, Mattheakis LC, Nomura M. Post-transcriptional regulation of the str operon in Escherichia coli. Ribosomal protein S7 inhibits coupled translation of S7 but not its independent translation. J Mol Biol 1994; 235:111-24. [PMID: 7507167 DOI: 10.1016/s0022-2836(05)80020-8] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The str operon of Escherichia coli consists of the genes for ribosomal proteins S12 (rpsL) and S7 (rpsG) and elongation factors G (fusA) and Tu (tufA). Previous studies have shown that S7 is a translational feedback repressor and inhibits the synthesis of itself and of elongation factor G. We have now shown that induction of S7 synthesis from the S7 gene fused to the arabinose promoter on a plasmid also leads to inhibition of the synthesis of S12 from the chromosomal S12 gene, and that this regulation takes place using the same target site as that used for distal gene regulation, i.e. S7 retroregulates S12. We have then demonstrated that S7 synthesis is mostly translationally coupled with the translation of the preceding S12 gene. Using a rpsG'-'lacZ fusion gene as a reporter for S7 synthesis, we found that abolishing S12 translation by a mutational alteration of the AUG start codon of the S12 gene leads to about tenfold reduction of S7 synthesis without significantly affecting its rate of transcription. Deletion of the proximal portion of the S12 gene or a premature termination of S12 translation by an amber mutation at the 26th codon also led to a large reduction of S7 synthesis. Unexpectedly, we have discovered that overproduction of S7 in trans from a plasmid leads to repression of the rpsG'-'lacZ fusion gene when the fusion gene is preceded by the intact S12 gene, but not when the S12 gene carried the above-mentioned mutations that abolish S12 translation. Thus, a novel feature of this regulatory system is that translation of S7 achieved by independent initiation is not inhibited by S7 in vivo, whereas translation of S7 achieved by translational coupling is sensitive to S7 repression. These observations also suggest that the coupled S7 translation is probably achieved by the use of ribosomal subunits employed for translation of the upstream S12 gene.
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1620
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Saito K, Nomura M. Post-transcriptional regulation of the str operon in Escherichia coli. Structural and mutational analysis of the target site for translational repressor S7. J Mol Biol 1994; 235:125-39. [PMID: 8289236 DOI: 10.1016/s0022-2836(05)80021-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In the Escherichia coli str operon, translation of the S12 and S7 genes is largely coupled, and the translational repressor S7 inhibits S7 translation, which is coupled to that of S12, but does not inhibit independent translation of S7 by free ribosomes in the intracellular pool. We have studied the S12-S7 intercistronic region of mRNA by analyzing RNA synthesized in vitro using structure-specific nucleases and a chemical probe, dimethyl sulfate. Based on the results obtained, we have deduced a secondary structure model of the S12-S7 intercistronic region and identified nucleotide residues "protected" by S7. We then carried out site-directed mutagenesis to identify nucleotide residues important for S7 translation as well as for repression by S7. The results showed that two distinct regions are important for S7-mediated repression; one is the S7 binding region identified by the protection analysis and the second is the stem structure that sequesters the Shine-Dalgarno sequence for the S7 gene. Some of the base alterations in the first region abolished S7 binding and, as a consequence, abolished S7-mediated repression, without affecting the efficiency of S7 translation. Other mutations disrupting the stem structure in the second region abolished S7-mediated repression without significantly affecting the S7-mRNA interaction. We also found that certain mutations drastically decrease S7 translation achieved by translational coupling without affecting S7 translation achieved by independent initiation. These mutations are in base-paired regions and evidence was obtained to suggest that these base-paired structures are important for translational coupling. We suggest that some specific RNA structures in the intercistronic region play an active role in achieving translational coupling in this system, and that repression of S7 translation by S7 protein is due to disruption of such structures induced by binding of S7 protein to the target site, rendering translational coupling very inefficient, but leaving independent translation initiation unaffected.
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1621
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Tamura G, Maesawa C, Suzuki Y, Kashiwaba M, Ishida M, Saito K, Satodate R. Improved detection of loss of heterozygosity at retinoblastoma gene locus in human breast carcinoma. Pathol Int 1994; 44:34-8. [PMID: 8025647 DOI: 10.1111/j.1440-1827.1994.tb02583.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Loss of heterozygosity (LOH) at the retinoblastoma (Rb) gene locus was investigated in 33 breast carcinomas by polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis after tumor cell enrichment by cell sorting. The efficacy of cell sorting was evaluated by comparing the results of PCR-SSCP with and without cell sorting. Ten of 17 (59%) informative cases showed LOH at this locus by cell sorting combined with PCR-SSCP, although LOH was detectable in six (35%) cases without cell sorting. Flow cytometry and histologic examination revealed that this underestimation may occur when the tumor cell population is less than 50% in the specimens analyzed. It is concluded that LOH of the Rb gene occurs more frequently in human breast carcinoma than previously thought, and thus may contribute significantly to the development and/or progression of this tumor.
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1622
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Nakano H, Saito K, Suzuki K. Chronic implantation technique for monopolar EEG monitoring of epileptic seizures in mice. Brain Res Bull 1994; 35:261-8. [PMID: 7812807 DOI: 10.1016/0361-9230(94)90132-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The implanted system was composed of four silver ball electrodes placed in the burr hole of the skull, a reference placed subcutaneously near the nose, two electrodes for EMG, and a ground. The dural attachment was 0.1 mm in diameter. A cassette connector was placed on the back. Implanted cables between the cassette connector and all electrodes consist of twisted fine wires placed in a silicone tube 0.5 mm in diameter. The implanted electrode system weighed 0.8 g. The outlet cables were of the same materials used for implanted cables and placed in a silicone tube 1.5 mm in diameter. The impedance matching between these cables was successful and assured the minimum contamination of artifacts in the EEG recording of freely moving mice. Long-term (4-5 weeks) recording, thus, became possible without damage to the implanted materials. Monopolar recordings demonstrated the localized paroxysmal discharges during general tonic clonic convulsion in El mice. Several artifacts are presented.
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1623
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Saito K. [Molecular genetics and biotechnology in medicinal plants: studies by transgenic plants]. YAKUGAKU ZASSHI 1994; 114:1-20. [PMID: 8133455 DOI: 10.1248/yakushi1947.114.1_1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The advances in molecular genetics and biotechnology in the field of medicinal plant research are discussed with focusing on the works using transgenic plants. Differentiated organ cultures and transgenic teratomas, incited by the infection with mutants of Agrobacterium Ti and Ri plasmids, were established in quinolizidine-alkaloid producing plants and Solanaceae plants. These cultured cells were used for the production and bioconversion of specific alkaloids produced in these plants. The methods of integration of foreign genes into medicinal plants were developed using an Ri binary vector. The mode of gene expression driven by TR1'-2' promoters was elucidated in transgenic medicinal plants, e.g., Nicotiana tabacum, Glycyrrhiza uralensis, Digitalis purpurea and Atropa belladonna. The genes for herbicide resistance, mammalian cytochrome P450 and bacterial beta-hydroxydecanoylthioester dehydrase were transferred and expressed in plants either to confer herbicide-resistant trait or to change the pattern of metabolites. The cDNA clones encoding cysteine synthase responsible for sulfur assimilation and biosynthesis of non-protein amino acids were isolated and characterized from Spinacea oleracea and Citrullus vulgaris. The functional lysine residue was identified by site-directed mutagenesis experiments. An over-expression system in Escherichia coli was constructed for the bacterial production of the plant specific non-protein amino acids. We made transgenic N. tabacum integrated with sense- and antisense-constructs of cysteine synthase cDNA driven by cauliflower mosaic virus 35S promoter for the purpose of genetic manipulation of biosynthetic flow of cysteine in plants. The future prospects of medicinal plant research are also discussed in the context of modern plant molecular biology.
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1624
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Saito K, Nakaya Y, Miyoshi Y, Wakatsuki T, Nomura M, Shono M. Effects of vesnarinone (OPC-8212) on Ca(2+)-activated K channels and cytosolic Ca2+ in cultured smooth muscle cells from porcine coronary artery. JAPANESE HEART JOURNAL 1994; 35:61-71. [PMID: 8201782 DOI: 10.1536/ihj.35.61] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Vesnarinone is a new, non vasodilating cardiotonic agent. This study compared the effects of vesnarinone and amrinone, a phosphodiesterase (PDE) inhibitors with vasodilating actions, on cultured smooth muscle cells from the porcine coronary artery. Application of vesnarinone (10(-4) M) or amrinone (10(-4) M) to the bath solution in cell-attached patches activated the KCa channel having a conductance of 133 pS (bath 2.7 mM K, pipette 140 mM K). Application of vesnarinone to the cytosolic side had no direct effect on KCa channel activities in inside-out patches. Activation of the KCa channel was suppressed when the intracellular production of cAMP was suppressed by preincubation with carbachol (10(-6) M). Amrinone, but not vesnarinone, lowered [Ca2+]i in the K(+)-depolarized smooth muscle cells (K+ = 70 mM). These results suggest that vesnarinone exerts an additional effect on [Ca2+]i that is independent of PDE inhibition. The difference in the effects on [Ca2+]i in vascular smooth muscle cells may explain in part the differing actions of these agents on vascular relaxation.
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1625
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Takayasu T, Saito K, Nishigami J, Ohshima T, Nagano T. Toxicological analysis of drugs and poisons in formalin-fixed organ tissues. 2. Volatile substances. Int J Legal Med 1994; 107:7-12. [PMID: 7999648 DOI: 10.1007/bf01247267] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Diethylether, chloroform and toluene were administered by inhalation and ethanol intravenously to rabbits. As soon as possible after death, tissue specimens were collected from the brain, lung, liver, kidney and skeletal muscle and fixed in non-buffered 10% formalin at room temperature (10-20 degrees C) for 4 different periods (1, 2, 5 and 14 days). The volatile substances were analyzed and identified by gas chromatography/mass spectrometry (GC-MS). The measured concentrations of ethanol, diethylether, chloroform and toluene in the brain tissue 1 day after fixation decreased to 8, 23, 73 and 84% respectively compared with those in the non-fixed brain tissue (100%). The rank order of the rate of decrease in the fixed state was: ethanol > diethylether >> chloroform > toluene. These volatile substances could be detected clearly in all the tissue specimens, even after a 14-day fixation period. These results provide useful toxicological information that will help to differentiate whether volatile substances have been administered antemortem or postmortem.
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