Microparticle release from platelets by leukemic cell lines.
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Blood Coagulation↗
Biomedical subjects
H Kido
Publications and source records attributed to H Kido.
Assignment of disulfide bridges in the fusion glycoprotein of Sendai virus.
The mature fusion (F) glycoprotein of the paramyxovirus family consists of two disulfide-linked subunits, the N-terminal F2 and the C-terminal F1 subunits, and contains 10 cysteine residues which are highly conserved at specific positions. The high level of conservation strongly suggests that they are indeed disulfide linked and play important roles in the folding and functioning of the molecule. However, it has not even been clarified which cysteine residues link the F2 and F1 subunits. This report describes our assignment of the disulfide bridges in purified Sendai virus F glycoprotein by fragmentation of the polypeptide and isolation of cystine-containing peptides and determination of their N-terminal sequences. The data demonstrate that all of the 10 cysteine residues participate in disulfide bridges and that Cys-70, the only cysteine in F2, and Cys-199, the most upstream cysteine in F1, form the interchain bond. Of the remaining eight cysteine residues clustered near the transmembrane domain of F1, the specific bridges identified are Cys-338 to Cys-347 and Cys-362 to Cys-370. Although no exact pairings between the subsequent four residues were defined, it seems likely that the most downstream, Cys-424, is linked to Cys-394, Cys-399, or Cys-401. Thus, we conclude that the cysteine-rich domain indeed contributes to the formation of a bunched structure containing at least two tandem cystine loops.
Amino Acid Sequence↗
Effect of three Japanese kampo medicines on platelet activation by monoclonal anti-platelet membrane glycoprotein antibodies.
We studied the effect of three Japanese kampo medicines on platelet activation by an anti-CD9 monoclonal antibody (NNKY1-19) and an anti-human Fc gamma receptor II monoclonal antibody (NNKY3-2). Sho-saiko-to (TJ-9) and Sairei-to (TJ-114) partially suppressed platelet aggregation induced by NNKY1-19, while Juzen-taiho-to (TJ-48) suppressed aggregation induced by NNKY3-2. TJ-9 and TJ-114 also suppressed collagen-induced aggregation, but TJ-48 did not. Flow cytometry showed that the three medicines did not affect antibody binding to the platelets. Thus, all three kampo medicines suppressed platelet activation by anti-platelet glycoprotein antibodies without inhibiting antibody binding.
Antibodies, Monoclonal↗
Correlations between quantitative EEG and regional cerebral blood flow (SPECT) in patients with partial epilepsy.
During interictal periods in 9 patients with partial epilepsy we examined whether there were correlations between the relative power of background EEG (power spectral analysis) and the absolute values of regional cerebral blood flow (rCBF) measured by 99mTc hexamethylpropylene amine oxime (HMPAO) SPECT in each cerebral region. None of the patients had any organic cerebral lesions on X-ray CT examinations, neurological abnormalities or mental retardation. There was an inverse correlation between rCBF and the relative power of the theta band, and a direct correlation between rCBF and that of the alpha band of 10-12.8 Hz, in the right and/or left frontal, parietal and temporal regions. In the occipital regions, there was a direct correlation only between rCBF and the relative power of the beta band. These correlations were noted whether the analyzed regions were epileptic foci or not. These results suggest that background EEG and rCBF changes in epileptic patients are closely coupled.
Adult↗
Diuretic and vasodilating actions of torasemide.
The pharmacological profile of torasemide was examined in experimental animals. In normotensive Wistar rats, torasemide produced less kaliuresis at doses that were equipotent with furosemide in terms of natriuresis. Torasemide but not furosemide exerted a significant diuretic action in rats treated with deoxycorticosterone acetate. Both torasemide and furosemide increased plasma renin activity and aldosterone concentration, but only torasemide significantly inhibited aldosterone-receptor binding in rat kidney. Torasemide also inhibited vasoconstriction induced by thromboxane A2 in isolated canine coronary artery.
Aldosterone↗
Analysis of platelet abnormalities in uremia with and without Glanzmann's thrombasthenia.
Uremia causes a bleeding tendency associated with platelet dysfunction, and previous studies have shown abnormalities of platelet glycoprotein (GP) Ib or GPIIb/IIIa and a tendency for platelet activation in uremia. The present study compared the abnormalities of platelet function in uremia with (n = 1) or without (n = 18) associated Glanzmann's thrombasthenia. There was a significant difference between ristocetin-induced agglutination of platelets from the uremic patients without Glanzmann's thrombasthenia and platelets from healthy controls (n = 15). In addition, a reduction of GPIb expression by uremic platelets along with normal GPIIb/IIIa expression was confirmed using flow cytometry. Many coagulation markers were increased in the uremic patient with Glanzmann's thrombasthenia, suggesting that the coagulation was enhanced and the platelets were prone to activation. However, the thrombasthenic platelets actually showed little increase in the binding of a monoclonal anti-CD63 antibody directed against lysosomal integral membrane protein (which is expressed after platelet activation), while uremic platelets showed a marked increase. In addition, the expression of GPIb by thrombasthenic platelets was normal, while that of GPIIb/IIIa was markedly decreased. Our results suggest that thrombasthenic platelets are resistant to activation and to the degradation of GPIb under uremic condition and that this difference from 'ordinary' uremic platelets be related to the difference in GPIIb/IIIa.
Adult↗
Sendai virus infection changes the subcellular localization of tryptase Clara in rat bronchiolar epithelial cells.
Tryptase Clara activates the infectivity of Sendai and influenza viruses proteolytically. In this study, we investigated changes in the subcellular localization of tryptase Clara in rat bronchioles with progression of Sendai virus infection. Tryptase Clara and Sendai virus F2 antigen were localized by light and electron immunohistochemical studies. In the uninfected rat lung, tryptase Clara was specifically localized in the secretory granules of respiratory bronchiolar epithelial nonciliated cells, but not in bronchiolar ciliated, or alveolar cells. In the initial stage of Sendai virus infection with slight pathological changes, however, anti-tryptase Clara was highly reactive in luminal peripheral membranes of both nonciliated and ciliated epithelial cells of the bronchioles together with some Sendai virus envelope glycoprotein, F2 antigen. In the progressed stage, tryptase Clara was hard to detect, with heavy accumulation of F2 antigen in the epithelial cells. These immunohistochemical results support our previous findings that in the bronchial lavage fluid tryptase Clara is significantly increased both in amount and activity after viral infection. These results suggest that Sendai virus stimulates the secretion of tryptase Clara from nonciliated bronchiolar epithelial cells to the airway lumen. Accumulation of tryptase Clara on the luminal surface of the bronchiolar epithelial cells and/or in the airway lumen may produce favourable conditions for proteolytic viral activation and multiplication.
Animals↗
The effects of dobutamine, propranolol and nitroglycerin on an experimental canine model of congestive heart failure.
A new experimental model of acute congestive heart failure was established in open-chest dogs, and it was employed to examine the effects of dobutamine, propranolol and nitroglycerin. The model was induced by intracoronary administration of saponin, volume loading and intravenous infusion of methoxamine. Left ventricular end-diastolic pressure (LVEDP) increased from 7.9 +/- 0.6 to 24.2 +/- 1.4 mmHg, and aortic blood flow (AoF) decreased from 0.89 +/- 0.06 to 0.53 +/- 0.04 l/min. Systemic vascular resistance (SVR) increased from 9618 +/- 585 to 16492 +/- 1213 dynes.sec/cm5 and right atrial pressure (RAP) increased from 2.5 +/- 0.2 to 4.2 +/- 0.4 mmHg. Furthermore, Vmax decreased from 71.6 +/- 5.1 to 45.8 +/- 2.9 1/sec, and the time constant of left ventricular pressure decay (T) increased from 40.0 +/- 2.6 to 90.2 +/- 7.9 msec. These hemodynamic changes were stable for up to 80 min. Dobutamine improved cardiac function by increasing Vmax and by decreasing T. Consequently, dobutamine increased AoF and decreased LVEDP, while there was no change in SVR. Nitroglycerin reduced LVEDP, SVR and T; increased AoF; and did not change Vmax. Propranolol produced no improvement in the hemodynamics or cardiac function. These results indicate that the present congestive heart failure model is characterized by global left ventricular dysfunction with lowered cardiac output and increased peripheral vascular tone, and it is beneficial for evaluating the pharmacological properties of drugs for acute congestive heart failure.
Analysis of Variance↗
Effect of cepharanthin and cytochalasin D on platelet internalization of anti-glycoprotein IIb/IIIa antibodies.
The effects of cepharanthin and cytochalasin D on the internalization of anti-glycoprotein IIb/IIIa antibodies by platelets were investigated in 13 patients with chronic immune thrombocytopenic purpura who had circulating anti-glycoprotein IIb/IIIa autoantibodies. Unfixed platelets were incubated with a monoclonal anti-glycoprotein IIb/IIIa antibody (NNKY1-32) or with platelet-binding IgG from the patients (which contained anti-glycoprotein IIb/IIIa antibodies). Flow cytometry showed that the binding of NNKY1-32 to platelets was markedly decreased after incubation for 120 min compared with incubation for 10 min. This decrease was inhibited by cepharanthin but not by cytochalasin D. Platelet-binding IgG also showed markedly reduced binding after incubation for 120 min compared with 10 min, and this decrease was inhibited by both cepharanthin and cytochalasin D. Cytochalasin D inhibits platelet cytoskeletal activity while cepharanthin does not. Therefore, our results suggest that the internalization of anti-glycoprotein IIb/IIIa antibodies from the plasma of patients with immune thrombocytopenic purpura is related to platelet cytoskeletal reorganization, while the cytoskeleton did not participate in internalization of the monoclonal anti-glycoprotein IIb/IIIa antibody (NNKY1-32). Cepharanthin may be useful for studying the internalization and cycling of glycoprotein IIb/IIIa in human platelets, and it may also be potentially useful for the treatment of immune thrombocytopenic purpura.
Alkaloids↗
Amyloid beta-protein precursor-rich platelet microparticles in thrombotic disease.
We investigated the association of amyloid beta-protein precursor (APP) and platelet derived microparticles in 20 normal controls and 91 patients with various diseases causing a thrombotic tendency. Compared with the controls, the mean percentage of APP-positive microparticles was significantly greater in the patients with cerebral infarction (39.1 +/- 17.7%, p < 0.001), diabetes (31.1 +/- 12.6%, p < 0.001), and uremia (30.1 +/- 14.7%, p < 0.01), but not in those with hypertension (8.2 +/- 6.3%, p = NS). Sixteen patients with cerebral infarction, 20 with diabetes, and 11 with uremia had microparticles with very high APP levels. In normal controls, 7.2 +/- 3.7% of the microparticles were positive for P-selectin, while the percentage in cerebral infarction, diabetes, uremia, and hypertension was respectively 43.5 +/- 15.1%, 40.0 +/- 12.8%, 31.8 +/- 12.2%, and 11.6 +/- 7.3%. There was a significant correlation between P-selectin and APP positivity of microparticles. Our results suggest that microparticle APP may have a regulatory influence on coagulation abnormalities.
Amyloid beta-Protein Precursor↗
Purification of meprin from human kidney and its role in parathyroid hormone degradation.
Meprin (EC 3.4.24.18) is known to occur in the kidneys of mice and rats, but has not previously been found in human kidneys. Here we report the isolation of meprin from human kidney and show that it has a role in the degradation of parathyroid hormone (PTH) in that organ. The purified human meprin had properties almost identical to those of rat meprin including molecular size, substrate specificity and inhibitor sensitivity, and it also cross-reacted well with an antibody raised against rat meprin. Both the purified human meprin and the microvillar membranes of human kidney readily hydrolyzed human parathyroid hormone [hPTH-(1-84)] into several fragments, whose amino acid sequences corresponded well to each other. Thus, meprin appears to play a major role in the PTH-degrading activity in the microvillar membranes of human kidney. Our results indicate that meprin, which so far has mainly been investigated in mice and rats, is found not only in these rodents, but also in the human kidney, and suggest that its physiological role in humans is to degrade PTH in the kidney.
Amino Acid Sequence↗
[Role of cellular proteases in virus infection: influenza virus and HIV infection].
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Animals↗
Interaction of hepatitis B virus X protein with a serine protease, tryptase TL2 as an inhibitor.
X protein of hepatitis B virus (HBV) transactivates transcription of various viral and cellular genes. It has been suggested that X protein plays a major role in hepatocarcinogenesis by HBV. The protein possesses amino acid sequence homology to the functionally essential domain of Kunitz-type serine protease inhibitors. This Kunitz domain-like sequence in X protein is indispensable for the transactivation function. To clarify whether X protein has a serine protease inhibitor activity, a search was made for serine proteases which interact with, but not degrade X protein. Tryptase TL2, one of serine proteases in hepatic cells, was found to directly interact with X protein without degradation. Moreover, the activities of tryptase TL2 and an analogous protease were substantially inhibited by X protein. These results suggest that transactivation function of X protein is exerted by modulation of the hepatic serine protease activity, giving rise to quantitative or qualitative change of cellular transcription factor(s) through protection from proteolytic degradation and/or suppression of processing.
Amino Acid Sequence↗
Detection of CD68-positive microparticles in immune thrombocytopenic purpura.
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Antigens, CD↗
Processing protease for gp160 human immunodeficiency virus type I envelope glycoprotein precursor in human T4+ lymphocytes. Purification and characterization.
A processing protease for the human immunodeficiency virus type I (HIV-I) envelope glycoprotein gp160 precursor has been purified to homogeneity from the post-nuclear membrane fraction of a human T4+ lymphocyte clone. Most of the processing activity was found to be present in the fractions of endoplasmic reticulum and Golgi apparatus of the cells. The purified enzyme has a monomeric structure with a molecular mass of 26 +/- 3 kDa, as judged by gel-permeation liquid chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing and nonreducing conditions. The purified enzyme converted gp160 to gp120 and gp41, showing a pH optimum of 6.5-7.0. Direct amino acid sequencing of the amino terminus of the product gp41 revealed that the cleavage site of gp160 was between Arg511 and Ala512. The enzyme activity was inhibited by trypsin-type protease inhibitors, but was not affected by CaCl2, MgCl2 or chelating agents. The properties of the purified enzyme are clearly distinct from those of processing proteases reported previously. Although the significance of the enzyme in vivo is not currently certain, judging from its cleavage specificity and subcellular localization, this endopeptidase appears to be a processing enzyme for the human immunodeficiency virus type I gp160 precursor protein in human T cells.
Amino Acid Sequence↗
Participation of cathepsin B in processing of antigen presentation to MHC class II.
Cellular and humoral immune responses to vaccines of hepatitis B type and rabies were inhibited by specific inhibitors of cathepsin B, specific synthetic substrates of cathepsin B and anti-cathepsin B antibody. Therefore the lysosomal cathepsin B of antigen presenting cells plays an essential role in processing of these antigens for presentation to MHC class II. One of the active sites of cathepsin B, VN217-222 shares highly homologous sequences with a part of the desetope, a binding domain of antigenic peptides, VN57-62 of MHC class II, beta-chain. This evidence suggests that the peptides processed by the substrate specificity of cathepsin B exhibit a common affinity to bind with the desetope of MHC class II, beta-chain.
Amino Acid Sequence↗
Purification and molecular cloning of chymase from human tonsils.
A chymotrypsin-like protease was purified to homogeneity from human tonsils by a series of chromatographic procedures. The purified enzyme gave a single protein band with an apparent molecular mass of 30 kDa on SDS-PAGE. The sequence of the first 21 amino acids at the N-terminus of the enzyme was determined. A cDNA for the enzyme was cloned by PCR amplification from extracted tonsillar mRNA using a supposed N-terminal oligonucleotide primer and a conserved C-terminal primer of the chymase family. The deduced amino acid sequence of the isolated clone was identical to that of human chymase in connective tissue-type mast cells from heart except for a Ser instead of a Cys at the N-terminal 7th position.
Amino Acid Sequence↗
Pulmonary surfactant is a potential endogenous inhibitor of proteolytic activation of Sendai virus and influenza A virus.
The pathogenicities of influenza viruses and paramyxoviruses have been proposed to be primarily determined by a host cell protease(s) that activates viral infectivity by proteolytic cleavage of the envelope glycoproteins. We recently isolated a trypsin-type endoprotease, named tryptase Clara, from rat bronchial and bronchiolar epithelial Clara cells, which is secreted into the airway lumen and activates Sendai virus and influenza A virus proteolytically. We report here that surfactant in the bronchial fluid inhibited tryptase Clara specifically, having a Ki value of 0.13 microM, and inhibited the proteolytic activations by tryptase Clara in vitro and in organ cultures of rat lung. Intranasal infection of rats with Sendai virus was shown to stimulate secretion of tryptase Clara without changing the amount of surfactant in the bronchial lumen, resulting in a preferable condition for proteolytic viral activation and multiplication.
Amino Acid Sequence↗