Biomedical subjects

C M Teng

Publications and source records attributed to C M Teng.

At least 235 records · Page 13Linked to original sources

PubMed1989

Edematous response caused by [Thi5,8,D-Phe7]bradykinin, a B2 receptor antagonist, is due to mast cell degranulation.

[Thi5,8,D-Phe7]bradykinin caused hind-paw edema and degranulation of isolated peritoneal mast cells in a dose-dependent manner. Pretreatment with diphenhydramine/methysergide or compound 48/80 completely suppressed the edematous response caused by [Thi5,8,D-Phe7]bradykinin, whereas bradykinin-induced hind-paw swelling was only partially inhibited by diphenhydramine and methysergide pretreatment; the residual response was significantly further depressed by [Thi5,8,D-Phe7]bradykinin. Neither the bradykinin- nor [Thi5,8,D-Phe7]bradykinin-induced edematous response was significantly affected by aspirin or BW755C. The mast cell degranulation caused by [Thi5,8,D-Phe7]bradykinin and bradykinin was inhibited by gangliosides but not by heparin. These results suggest that the edematous response elicited by [Thi5,8,D-Phe7]bradykinin was mainly due to the actions of mediators released by the degranulation of mast cells. Unlike bradykinin, [Thi5,8,D-Phe7]bradykinin was devoid of a direct exudation-promoting effect but exerted an antagonistic effect on the direct effect of kinin. If the influence of mast cells degranulation could be minimized, [Thi5,8,D-Phe7]bradykinin could be used as a tool to evaluate the role of kinin in the edematous response in inflammation.

Animals↗

PubMed1989

Roles of mast cells and PMN leukocytes in cardiotoxin-induced rat paw edema.

Cardiotoxin, isolated from the venom of Naja naja atra, was found to cause rat hind-paw edema in a dose-dependent manner. This edematous response was significantly suppressed by pretreatment with diphenhydramine, methysergide or compound 48/80, which reduced the tissue histamine content. Polymorphonuclear (PMN) leukocyte infiltration appeared within 1 h and had accumulated markedly in the rat paw 3-6 h after subplantar injection of cardiotoxin. Methotrexate pretreatment significantly reduced not only the peripheral leukocyte count but also cardiotoxin-induced paw edema. Captopril, a kininase inhibitor, potentiated the edematous response caused by a low dose of cardiotoxin. The initial phase, occurring within 3 h, of paw edema induced by cardiotoxin was suppressed by trasylol, [Thi5,8,D-Phe7]bradykinin, or by cellulose sulfate pretreatment which greatly reduced plasma kininogen levels. Both mast cells and PMN leukocytes possess kinin-forming activities, but with different properties. The kinin-forming activity of mast cells but not of PMN leukocytes was inhibited by trasylol. In isolated mast cells, cardiotoxin caused a dose-dependent release of histamine, beta-glucuronidase, lactate dehydrogenase and kinin-forming activity. These observations suggest that mast cells and PMN leukocytes are involved in cardiotoxin-induced paw edema, and that inflammatory mediators such as histamine, serotonin and kinins were supplied directly or indirectly by mast cells, at least in the initial phase.

Animals↗

PubMed1989

Edema-producing proteins isolated from Trimeresurus mucrosquamatus snake venom.

Seven edema-producing fractions were isolated from Trimeresurus mucrosquamatus snake venom by CM-Sephadex C-50 chromatography and further purified by gel filtration on a Sephadex G-75 column. They were homogeneous as judged by electrophoresis on polyacrylamide gels. The mol. wts were estimated to be 26,900 (Fr. IV-2), 21,500 (Fr. X-2), 23,000 (Fr. XII-2), 21,800 (Fr. XIII-2), 24,600 (Fr. XIV-2), 80,000 (Fr. XVIII-1) and 22,500 (Fr. XXII-2). Fraction IV-2 had weak esterase activity, fractions X-2, XII-2, XIII-2 and XIV-2 possessed proteolytic activity toward casein and fibrinogen, while fractions XVIII-1 and XXII-2 possessed phospholipase A2 activity. Fractions with phospholipase A2 activity had greater edema-producing activity than those with protease and/or esterase activity. It is concluded that the edema caused by T. mucrosquamatus venom may be due to phospholipases A2, proteases and esterases.

Amino Acids↗

PubMed1989

Effects of venom proteases on peptide chromogenic substrates and bovine prothrombin.

Eighteen proteases were isolated from six hemorrhagic venoms of snakes belonging to the families of Crotalidae and Viperidae. According to their actions, they are classified as thrombin-like enzymes, alpha-fibrinogenases, beta-fibrinogenases, Factor X activator, prothrombin activator, hemorrhagins and esterases. Thrombin-like enzymes, beta-fibrinogenases, hemorrhagins and esterase hydrolyzed Phe-Pip-Arg-pNA (S-2238, substrate for thrombin) more strongly than CBZ-Ile-Glu-Gly-Arg-pNA (S-2222, substrate for Factor Xa), CBZ-Phe-Val-Arg-pNA (B-7632) or CBZ-Pro-Phe-Arg-pNA (B-2133). Thrombin-like enzymes, beta-fibrinogenase and esterase hydrolyzed tosyl-L-arginine methyl ester and benzoyl-L-arginine ethyl ester. S-2238 is the most susceptible chromogenic substrate for most venom proteases. Thrombin-like enzymes degraded prothrombin molecule progressively down to prethrombin 2 while alpha- and beta-fibrinogenases degraded it only to prethrombin 1. Factor X activator of Vipera russelli venom and esterase of T. mucrosquamatus venom did not have any effect on prothrombin. Thus, the effects of venom proteases on prothrombin are not parallel to their amidolytic or esterolytic effects.

Animals↗

PubMed1989

Edema formation and degranulation of mast cells by a basic phospholipase A2 purified from Trimeresurus mucrosquamatus snake venom.

The basic phospholipase A2 (PLA2) purified from Trimeresurus mucrosquamatus snake venom was injected into the subplantar in order to induce edema formation in the rat hind paw. The maximum edema induced by PLA2 was induced at 1-2 hr after injection, and the per cent swelling curve showed a dose-dependent increase by PLA2 injection (2.5-10.0 micrograms). The rate of edema formation is different from the acute swelling induced by T. mucrosquamatus venom (TMV). Pretreatment with dexamethasone (4 mg/kg, s.c.), indomethacin (10 mg/kg, per 05) and diphenhydramine (100 mg/kg s.c.) inhibited the edema induced by the purified phospholipase A2. The injection of purified PLA2 or venom into rabbit skin resulted in an increase in vascular permeability which could be decreased by pretreatment with three antiinflammatory drugs. However, the pharmacological effect of dexamethasone (4 mg/kg) demonstrated a more effective inhibition than the other drugs in the PLA2-induced edema and vascular permeability change. Injection (i.p.) of PLA2 caused marked degranulation of mast cells in the rat mesentery which was facilitated by addition of calcium ion (10 mM) but antagonized by pretreating with three antiinflammatory agents. After incubating peritoneal mast cells with PLA2 (1.0 micrograms/ml), the release of histamine from the mast cell was approximately 36%, this effect was inhibited by preincubating the mast cell with three antiinflammatory agents.

Animals↗

PubMed1989

The effect of cortisone on the eruption rate of root-resected incisors in the rat.

It is generally thought that the periodontal ligament plays a key--perhaps even exclusive--role in tooth eruption. The present study was designed to test the hypothesis that the fundus also may contribute to the process. To this end the effect of cortisone on the eruption rate of root-resected mandibular incisors was examined in male albino rats. Half of the animals received daily injections of cortisone; the other half were given normal saline. Impeded and unimpeded eruption rates were measured at 3-day intervals and tested for between- and among-means differences by repeated-measures analysis of variance (ANOVA). In contrast to the acceleration commonly seen in intact incisors, cortisone produced no change in the eruption rate of root-resected incisors. It was concluded therefore that the accelerative effect of cortisone is mediated by the fundus, rather than the periodontal ligament. Further, it is hypothesized that early eruption is controlled by cellular proliferation within the fundus; however, once the tooth enters the oral cavity and becomes functional, the periodontal ligament matures and becomes the dominant factor in subsequent eruption.

Alveolar Process↗

PubMed1988

Platelet aggregation induced by equinatoxin.

Equinatoxin, isolated from Actinia equina, caused aggregation of washed rabbit platelets at a concentration as low as 0.01 ng/ml. ATP was released, but no formation of thromboxane B2 in challenged platelets. The aggregation was resistant to indomethacin or creatine phosphate/creatine phosphokinase or PAF antagonist. The aggregation was inhibited by imipramine, sodium nitroprusside, mepacrine, theophylline, prostaglandin E1 and EDTA. However, heparin and tetracaine were without any inhibitory effect. Verapamil suppressed both the aggregation and release reaction caused by equinatoxin in calcium concentrations from 0.01 to 15 mM. High concentrations of equinatoxin caused progressive cell lysis. It is concluded that equinatoxin-induced platelet aggregation is independent of ADP, thromboxane or PAF pathway. Phosphoinositide breakdown by phospholipase C is postulated to accomplish this phospholipase A2-independent platelet aggregation by equinatoxin.

Adenosine Triphosphate↗

PubMed1988

Rat paw edema induced by trimucase II, a kinin-releasing enzyme from Trimeresurus mucrosquamatus venom.

Trimucase II, a proteolytic enzyme isolated from Trimeresurus mucrosquamatus venom, caused rat hind-paw edema dose dependently. Captopril potentiated significantly, while pretreatment with cellulose sulfate suppressed the trimucase II-induced edematous response. Pretreatment with diphenhydramine and methysergide reduced by 42 and 46% the edema induced by trimucase II and kallikrein, respectively. The residual response was significantly further depressed by [Thi5,8,D-Phe7]bradykinin and trasylol. Kinin generation by trimucase II was also found in vitro from plasma and was concentration- and time-dependent. Kinin formation was inhibited by soybean trypsin inhibitor, trasylol and endogenous kininase. The kinins released were destroyed by chymotrypsin. Unlike cellulose sulfate, trimucase II caused kinin formation from Factor XII-deficient and prekallikrein-deficient plasma but not from high molecular weight kininogen-deficient plasma. These data indicate that, in addition to the mediators released from mast cells, kinins have an important role in the edema caused by trimucase II, and that kinins are released from plasma, probably due to direct activation of kininogen.

Animals↗

PubMed1988

Two antiplatelet agents from Magnolia officinalis.

Magnolol and honokiol are two position isomers isolated from the bark of Magnolia officinalis. Both inhibited the aggregation and ATP release of rabbit platelet-rich plasma induced by collagen and arachidonic acid without affecting that induced by ADP, PAF or thrombin. Aggregation of washed platelets was more markedly inhibited than that of platelet-rich plasma, while the aggregation of whole blood was least affected by both inhibitors. Thromboxane B2 formation caused by collagen, arachidonic acid or thrombin was in each case inhibited by magnolol and honokiol. The rise of intracellular calcium caused by arachidonic acid or collagen was also suppressed by both agents. Collagen-induced intracellular calcium increase in the presence of indomethacin was suppressed by magnolol. It is concluded that the antiplatelet effect of magnolol and honokiol is due to an inhibitory effect on thromboxane formation and also an inhibition of intracellular calcium mobilization.

Animals↗

PubMed1988

Comparison of the platelet aggregation induced by three thrombin-like enzymes of snake venoms and thrombin.

Platelet aggregation induced by three thrombin-like enzymes of snake venoms was compared with that by thrombin. Acutin was isolated from Agkistrodon acutus venom and thrombocytin and batroxobin were from Bothrops atrox venom. The fibrinogen-clotting activities were 700, 170 and 7 U/mg for batroxobin, acutin and thrombocytin, respectively. They induced aggregation and ATP release of washed rabbit platelets. The aggregating activity of thrombin was 10(2), 10(4) and 10(5) times more potent than those of thrombocytin, acutin and batroxobin, respectively. Platelet-activating potency of the thrombin-like enzymes was correlated with their effectiveness on the retractility and elasticity of the clots. Platelet aggregation induced by thrombin or thrombocytin could be inhibited by heparin with antithrombin III while that by acutin or batroxobin could not. Indomethacin showed weak inhibition on the aggregation while the ADP-scavenging system, creatine phosphate/creatine phosphokinase, inhibited the aggregation induced by the three thrombin-like enzymes but not that by thrombin. Platelet aggregation induced by the thrombin-like enzymes could not be inhibited by PAF antagonists-BN 52021, kadsurenone or L-652,731. In the presence of EGTA, only thrombin could induce ATP release from platelets. Thrombin-like enzymes and low concentration of thrombin did not form thromboxane B2. Nitroprusside and prostaglandin E1 completely inhibited the aggregation, mepacrine and imipramine showed marked inhibition while verapamil had only weak inhibition. It is concluded that the aggregation induced by the thrombin-like enzymes is different from that of thrombin and mainly due to ADP released from platelets.

Adenosine Triphosphate↗

PubMed1987

Antiplatelet effect of butylidenephthalide.

Butylidenephthalide inhibited, in a dose-dependent manner, the aggregation and release reaction of washed rabbit platelets induced by collagen and arachidonic acid. Butylidenephthalide also inhibited slightly the platelet aggregation induced by PAF and ADP, but not that by thrombin or ionophore A23187. Thromboxane B2 formation caused by collagen, arachidonic acid, thrombin and ionophore A23187 was in each case markedly inhibited by butylidenephthalide. Butylidenephthalide inhibited the aggregation of ADP-refractory platelets, thrombin-degranulated platelets, chymotrypsin-treated platelets and platelets in the presence of creatine phosphate/creatine phosphokinase. Its inhibition of collagen-induced aggregation was more marked at lower Ca2+ concentrations in the medium. The aggregability of platelets inhibited by butylidenephthalide could be recovered after the washing of platelets. In human platelet-rich plasma, butylidenephthalide and indomethacin prevented the secondary aggregation and blocked ATP release from platelets induced by epinephrine. Prostaglandin E2 formed by the incubation of guinea-pig lung homogenate with arachidonic acid could be inhibited by butylidenephthalide, indomethacin and aspirin. It is concluded that the antiplatelet effect of butylidenephthalide is mainly due to an inhibitory effect on cyclo-oxygenase and may be due partly to interference with calcium mobilization.

Adenosine Diphosphate↗

PubMed1987

Cyclooxygenase--independent pathway of phospholipase activation in carrageenan--induced platelet aggregation.

Carrageenan induced aggregation and ATP release of washed rabbit platelets. The aggregation was resistant to indomethacin or creatine phosphate/creatine phosphokinase system but sensitive to mepacrine or p-bromophenacyl bromide. Chlorpromazine, verapamil or tetracaine inhibited carrageenan-induced aggregation, ATP release reaction and membrane-bound calcium redistribution in washed platelets. Agents elevating cyclic nucleotides selectively inhibited the release reaction without affecting the aggregation. The mechanism of carrageenan-mediated platelet responses may be due to both activation of phospholipases A2 and C. Platelet activating factor, protein kinase C and inositol triphosphate or phosphatidic acid could be mediated by carrageenan to accomplish the cyclooxygenase-independent events.

Animals↗

PubMed1987

Characterization of the anticoagulants from Taiwan cobra (Naja naja atra) snake venom.

Taiwan cobra (Naja naja atra) snake venom was separated into 19 fractions by means of CM-Sephadex C-50 column chromatography. Anticoagulant Fractions V-VII were refractionated by gel filtration on Sephadex G-50 and the purified component possessed phospholipase A2 activity and an inhibitory effect on collagen-induced platelet aggregation. The anticoagulant action could be antagonized by phospholipid or platelet factor 3. Anticoagulant Fraction XVII was also further refractionated by gel filtration on Sephadex G-50 and the purified component was shown to be cardiotoxin. It was a weak anticoagulant, caused direct hemolysis and potentiated collagen-induced platelet aggregation. Thromboelastographic studies showed that the anticoagulant action of cobra venom is due to the synergistic effects of phospholipase A2 and cardiotoxin.

Animals↗

PubMed1987

Effect of hsien-ho-t'sao (Agrimonia pilosa) on experimental thrombosis in mice.

The water extract of Hsien-Ho-T'sao (HHT) prolonged the tail bleeding time in conscious mice. This antihemostatic effect was dose-dependent and exhibited a biphasic pattern; i.e. its activity declined at doses higher than 0.5 mg/kg. the prolonged bleeding time persisted for at least 12 hr and maximal effect was observed at 3 hr after the oral administration of HHT 500 mg/kg. HHT was effective in preventing ADP-induced acute pulmonary thromboembolic death in mice, while aspirin and indomethacin had no effect on this model. HHT, like aspirin and indomethacin, also reduced the mortality in collagen- and sodium arachidonate-induced thromboembolic death. All three drugs caused no significant protection in endotoxin shock. HHT was found to suppress platelet aggregation markedly, but little effect on blood coagulation. In conclusion, HHT was proved to be effective in the treatment of acute pulmonary thromboembolism, and this effect was mainly due to its antiplatelet action.

Animals↗

PubMed1986

Effect of cobra venom phospholipase A2 on platelet aggregation in comparison with those produced by arachidonic acid and lysophophatidylcholine.

Cobra venom phospholipase A2 induced a biphasic effect on washed rabbit platelets. The first phase was a reversible aggregation which was dependent on stirring and extracellular calcium. The aggregation and thromboxane B2 formation were inhibited by indomethacin, mepacrine, tetracaine and imipramine, while PGE1 and sodium nitroprusside inhibited only the aggregation, but not the thromboxane B2 formation. The second phase was an inhibitory effect on platelet aggregation induced by arachidonic acid, PAF, ADP or collagen but not that by thrombin or ionophore A23187. The longer the incubation time of cobra venom phospholipase A2 with platelets, the more the inhibitory effect. The aggregating and anti-aggregating effects could be overcome by bovine serum albumin. Lysophosphatidylcholine (Lyso-PC) and arachidonic acid showed synergistic inhibition in platelet aggregation. Lyso-PC decreased thromboxane B2 formation in platelets formed by collagen. The inhibitory effect of Lyso-PC on platelet aggregation was more marked at lower calcium concentrations. It is concluded that the aggregating effect of exogenous addition of venom phospholipase A2 is due to thromboxane formation and the antiplatelet effect is similar to those produced by arachidonic acid and lysophosphatidylcholine.

Animals↗

PubMed1985

Action mechanism of the platelet aggregation inducer and inhibitor from Echis carinatus snake venom.

Platelet aggregation inducer and inhibitor were isolated from Echis carinatus snake venom. The venom inducer caused aggregation of washed rabbit platelets which could be inhibited completely by heparin or hirudin. The venom inducer also inhibited both the reversibility of platelet aggregation induced by ADP and the disaggregating effect of prostaglandin E1 on the aggregation induced by collagen in the presence of A23187, arachidonate, ADP and platelet-activating factor (PAF) with an IC50 of around 10 micrograms/ml. It did not inhibit the agglutination of formaldehyde-treated platelets induced by polylysine. In the presence of indomethacin or in ADP-refractory platelets or thrombin-degranulated platelets, the venom inhibitor further inhibited the collagen-induced aggregation. Fibrinogen antagonized competitively the inhibitory action of the venom inhibitor in collagen-induced aggregation. In chymotrypsin-treated platelets, the venom inhibitor abolished the aggregation induced by fibrinogen. It was concluded that the venom inducer caused platelet aggregation indirectly by the conversion of prothrombin to thrombin, while the venom inhibitor inhibited platelet aggregation by interfering with the interaction between fibrinogen and platelets.

Adenosine Diphosphate↗

PubMed1985

Characterization of the platelet aggregation inducer and inhibitor from Echis carinatus snake venom.

Echis carinatus venom was separated into twenty fractions by means of ultrafiltration and CM-Sephadex C-50 column chromatography. Fraction II possessed inhibitory activity on the aggregation of washed rabbit platelets and fraction XII possessed the procoagulant and platelet aggregation-inducing activity. Both were further purified by gel filtration on a Sephacryl S-200 column. The purified aggregation inducer was a glycoprotein with procoagulant activity 10-12-times that of the crude venom. It possessed proteinase and amidase but was devoid of esterase activity. The molecular weight was 16 000, and it contained 8.7% of neutral sugar. The isoelectric point was pH 7.6. The purified aggregation inhibitor was a single peptide chain with a molecular weight of 6800 and contained 22.1% of neutral sugar. The isoelectric point was pH 4.8. It was devoid of any enzymatic activity of the crude venom. The IC50 was about 10 micrograms/ml on the thrombin-induced platelet aggregation. The inhibitory activity was fully retained after the treatment of the venom aggregation inhibitor with neuraminidase, but was completely destroyed by sodium metaperiodate. Upon heat treatment at 90 degrees C, the venom aggregation inhibitor was heat stable at pH 5.5 for 4 h, but was completely destroyed after 2 h at pH 8.9 and retained about 50% of its inhibitory activity of the control at pH 7.2 for 4 h. The venom aggregation inhibitor decreased the elasticity of the whole blood clot, and this effect was related to its inhibitory action on platelet aggregation instead of blood coagulation.

Amino Acids↗

PubMed1985

Antihemostatic and antithrombotic effects of capsaicin in comparison with aspirin and indomethacin.

Capsaicin prolonged the tail bleeding time in the conscious mice. This effect was dose-dependent and maximal effect was observed at 3 hr after the oral administration. Capsaicin was effective in preventing death caused by ADP-induced acute pulmonary thromboembolism in mice at dose of 25 mg/kg, while aspirin and indomethacin had no effect at 200 mg/kg. Capsaicin also reduced the mortality in collagen- and sodium arachidonate-induced thromboembolic death at dose of 25 and 50 mg/kg, respectively, and aspirin and indomethacin were also effective in these models but only when the dose was higher than 200 mg/kg. Capsaicin, aspirin or indomethacin could not protect mice from endotoxin shock. Capsaicin was found to suppress platelet aggregation markedly, but did not affect blood coagulation. In conclusion, capsaicin was proved to be more effective than aspirin and indomethacin in preventing the death of acute pulmonary thromboembolism, and this effect could be due to its inhibition on platelet aggregation.

Adenosine Diphosphate↗