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71.
We determined the 240-nueleotide sequences of the E/NS1 gene junction of four dengue-2 viruses by the primer extension dideoxy chain termination method. These viruses were isolated from dengue patients with different clinical severities in Nakhon Phanom, Northeastern Thailand in 1993. The results were compared with the 52 published dengue-2 sequences of the same gene region. Sequence divergence of four new isolates varied from 4.17% to 5.42% compared with dengue-2 prototype New Guinea C strain whereas it varied from 5.42% to 6.67% and from 6.67% to 7.09% when compared with Jamaica 1409 strain and PR159/S1 strain, respectively. All nucleotide substitutions were found at the 3rd position of the codons which were silent mutations. All 56 isolates studied were classified into five genotypic groups by constructing the dendrogram. The results indicated that four new isolates from Northeastern Thailand belong to genotype II of dengue virus serotype 2, and were most closely related to prototype New Guinea C strain. We also observed the variation in nucleotide and amino acid sequences among clusters of isolates (Thailand-1980, Malaysia-1989 and Thailand-1993) which were obtained from the dengue patients with different clinical severities. The significance of these genetic differences have been discussed in terms of the possible correlation between genetic variability and virulence.  相似文献   
72.
Cultured endothelial cells isolated from bovine carotid aorta produce prostacyclin (prostaglandin I2) and a small amount of prostaglandin E2. The effects of kallikrein (EC 3.4.21.8) on the release of prostacyclin from the cells were studied with the radioimmunoassay technique. Kallikrein stimulated the release of prostacyclin in a dose-dependent manner. The maximal stimulation reached up to 9.2-fold at 0.1 micrograms/ml of kallikrein. The effect was not associated with the activation of the fatty acid cyclooxygenase, but with the stimulation of arachidonic acid release. But kallikrein itself did not have phospholipase activity. On the other hand, at the same doses, kallikrein failed to induce platelet aggregation or enhance platelet aggregation induced by collagen. Our findings suggest that the vasodilator effect of kallikrein is mediated in part by prostacyclin production. Furthermore, we investigated the possibility that the stimulatory effect of kallikrein on prostacyclin production in endothelial cells is associated with kinin formation. Bradykinin and lysylbradykinin (kallidin) also stimulated the release of prostacyclin, but the effects were far less than that of kallikrein. And the stimulation due to the addition of both kallikrein and bradykinin on prostacyclin and arachidonic acid release was not competitive or additive, but synergistic. Moreover, even if fetal calf serum was incubated with kallikrein, bradykinin was not detected at all. When kallikrein was pre-incubated with aporotinin, which is an inactivator of kallikrein, the effect of kallikrein was completely abolished. These findings suggest that the stimulatory effect of kallikrein on the release of prostacyclin from vascular cells is possibly not due to kinin formation, but to other substance(s) produced by this serine proteinase.  相似文献   
73.
5-Keto-D-[1-14C]gluconic acid, the most effective precursorof L(+)tartaric acid among all labeled compounds which haveever been tested in grapes, was found to be a good precursorof L(+)tartaric acid in a species of Pelargonium. The synthesisof labeled L(+)tartaric acid from D-[1-14C]glucose in Pelargoniumwas remarkably depressed when a 0.5% solution of D-gluconateor 5-keto-D-gluconate was administered continuously to leavestogether with D-[1-14C]glucose. Our results provide strong evidence that D-[1-14C]glucose ismetabolized in Pelargonium to give labeled L(+)tartaric acidvia (probably D-gluconic acid and) 5-keto-D-gluconic acid withoutpassing through L-ascorbic acid. Labeled L-idonic acid was found in young leaves of Pelargoniumwhich had been labeled with L-[U-14C]ascorbic acid. The synthesisof the labeled L-idonic acid increased when a 0.1% solutionof L-threonate was administered continuously to leaves togetherwith L-[U-14C]ascorbic acid. Specifically labeled compounds, recognized as the members ofthe synthetic pathway for L(+)tartaric acid from L-ascorbicacid via L-idonic acid in grapes, were administered to youngleaves of Pelargonium. Each compound (2-keto-L-[U-14C]idonicacid, L-[U-14C]idonic acid, 5-keto-D-[1-14C]gluconic acid and5-keto-D-[6-14C]gluconic acid) was partly metabolized, as ingrapes. The metabolic pathway starting from L-ascorbic acidto L(+)tartaric acid via L-idonic acid, however, did not actuallycontribute to the synthesis of L(+)tartaric acid in Pelargoniumprobably because the activity of each metabolic step was muchlower than that observed in grapes. (Received May 28, 1984; Accepted July 30, 1984)  相似文献   
74.
An endotoxin-activated hemocyte lysate from horseshoe crab (Tachypleus and Limulus) was found to hydrolyze specifically BZ-Ile-Glu-Gly-Arg-p-nitroanilide, which was recently introduced as the substrate for assay of the blood coagulation factor, Factor Xa. Further, this amidase activity increased by increasing the concentration of bacterial endotoxin (Salmonella minnesota R595) added to the lysate. Thus, the measurement of the amidase activity in the hemocyte lysate can be very useful to detect and determine the endotoxin.  相似文献   
75.
Twenty peptide-4-methylcoumarin amides (MCA) were newly synthesized and tested as possible substrates for alpha-thrombin, factor Xa, kallikreins, urokinase, and plasmin. These fluorogenic peptides contained arginine-MCA as the carboxyl-terminus. Release of 7-amino-4-methylcoumarin was determined fluorometrically. Of these peptides, the following were found to be specific substrates for individual enzymes: Boc-Val-Pro-Arg-MCA for alpha-thrombin, Boc-Ile-Glu-Gly-Arg-MCA, and Boc-Ser-Gly-Arg-MCA for factor Xa, Z-Phe-Arg-MCA for plasma kallikrein, Pro-Phe-Arg-MCA for pancreatic and urinary kallikreins, and glutaryl-Gly-Arg-MCA for urokinase. Moreover, these peptide-MCA substrates were resistant to plasmin.  相似文献   
76.
Previously reported PII-type α-glucosidase located in the precipitate of the labellar homogenate of the blowfly Phormia regina was solubilized by sodium deoxycholate (DOC) and further separated into three isozymes with different molecular weight: PII-M (mol. wt 9 × 104). PII-D (mol. wt 2 × 105) and PII-T (mol. wt 8 × 105) by molecular sieve chromatography on Biogel P-300 or Ultragel AcA-34. These three isozymes had almost the same Km's and relative values of Vm's for several substrates, suggesting that they had the same common active site.PII-D and PII-T are more strongly embedded in the membrane than PII-M, because the proportion of PII-D and PII-T was much increased when the remaining glucosidase in the precipitate after the first solubilization was reextracted by DOC. A large peak of α-glucosidase isozyme P-IV which preferentially hydrolyze sucrose eluted just after P-II (soluble P-II) when the supernatant fraction of the labellar homogenate was chromatographed on DEAE-Sephadex A-50. P-IV was scarcely present in the precipitate fraction.Soluble P-II had the same mol. wt as PII-M and had similar properties to PII-M except for the ratio of Vm's.A large proportion of PII-D was contained in the well washed labellar integuments, a preparation rich in labellar chemosensilla. It suggests that most of the insoluble α-glucosidase contained in the dendrite in labellar chemosensilla is PII-D. PII-D (and PII-T) are possible sites of the pyranose receptor molecule because their properties and localization agree well with those of the receptor.  相似文献   
77.
A 3-year-old boy with partial No. 9 tetrasomy is described. The patient showed markedly retarded physical and mental development as well as multiple congenital anomalies. Routine chromosome analysis revealed an extra C-group chromosome. It had a pronounced secondary constriction at the proximal part of its long arm. Based on studies by a variety of banding techniques, the extra chromosome was identified to be an iso-dicentric No. 9 chromosome with inactivation of one of the two centromeres, the karyotype being 47,XY, + DIC (9)(Q2101). The value of BrdUrd treatment was emphasized in the detection of a very small piece of euchromatin within a long stretch of constitutive heterochromatin.  相似文献   
78.
1. The holoenzyme of D-amino acid oxidase [D-amino acid: O2 oxidoreductase (deaminating), EC 1.4.3.3] was found to combine with 1-anilinonaphthalene-8-sulfonate without liberation of its coenzyme, FAD. No energy transfer interaction was found to occur between the bound dye and FAD of the holoenzyme. On the other hand, when the apoenzyme was bound to the dye and then to FAD, energy transfer interaction between the bound dye and bound FAD was observed. In both cases, the dye competes with the substrate, D-alanine. It is concluded that the dye bound to the holoenzyme is oriented in such a special manner that the mutual orientation factor between the dye and FAD becomes very small in magnitude. 2. When the apoenzyme combined with the dye, the monomer-dimer equilibrium of the apoenzyme shifted towards the dimer. On the other hand, 4-monobenzoylamido-4'-aminostilbene-2,2'-disulfonate combined with the apoenzyme to induce monomerization.  相似文献   
79.
Antigenic stimulation of rat basophilic leukemia cells sensitized with immunoglobulin E causes the release of histamine as well as arachidonic acid and its metabolites. The release of these substances is preceded by an increase in phospholipid methylation. Inhibition of phospholipid methylation is correlated to the inhibition of histamine release. Inhibition of methylation also reduces arachidonate release. Phospholipid methylation appears to be associated with both histamine secretion and the release of arachidonate and its metabolites.  相似文献   
80.
A small yet significant increase of immunoassayable pancreatic somatostatin concentration (0.107 +/- 0.005 vs. 0.156 +/- 0.017 microgram/g at 24 hr, p less than 0.05) was found in rats, 24 hr as well as 7 days after treatment with a diabetogenic dose of streptozotocin (65 mg/kg BW). These animals were characterized by marked decreases of insulin in the pancreas without any significant changes in pancreatic glucagon concentration. These results suggest that an abrupt deprivation of insulin from islets results in an elevation of pancreatic somatostatin concentration, and that glucagon in the pancreas plays a minor role in determining pancreatic somatostatin concentration in rats with insulin-deprived diabetes of short duration.  相似文献   
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