Pulp homogenates were incubated with [14C]-arachidonic acid and the metabolites separated by thin-layer chromatography. The main products of normal pulp were 6-keto-prostaglandin (PG) F1 alpha and 12-hydroxy-eicosatetraenoic acid (12-HETE), further identified by high performance-liquid chromatography. Thromboxane (TX) B2, and PGD2, E2 and F2 alpha were also detected at less than 30 per cent of 6-keto-PGF1 alpha. When the pulp was inflamed by applying bacterial lipopolysaccharide, production of all these metabolites increased; in particular, PGE2 was increased 9.3-fold compared with normal, and 6-keto-PGF1 alpha and HETE 3.8- and 2.0-fold, respectively. An unidentified product, slightly more polar than 12-HETE, was also markedly produced by the inflamed pulp. Thus arachidonic-acid metabolites including lipoxygenase products may be involved in the development of pulpal inflammation.

Background: Proprotein convertase subtilisin kexin type 9 inhibitors (PCSK9i) lower LDL-cholesterol and slow atherosclerosis preventing cardiovascular events. While it is known that circulating PCSK9 enhances platelet activation (PA) and that PCSK9i reduce it, the underlying mechanism is not still clarified. Methods: In a multicenter before-after study in 80 heterozygous familial hypercholesterolemia (HeFH) patients on treatment with maximum tolerated statin dose ± ezetimibe, PA, soluble-NOX2-derived peptide (sNOX2-dp), and oxidized-LDL (ox-LDL) were measured before and after six months of PCSK9i treatment. In vitro study investigates the effects of plasma from HeFH patients before and after PCK9i on PA in washed platelets (wPLTs) from healthy subjects. Results: Compared to baseline, PCSK9i reduced the serum levels of LDL-c, ox-LDL, Thromboxane (Tx) B2, sNOX2-dp, and PCSK9 (p < 0.001). The decrease of TxB2 correlates with that of ox-LDL, while ox-LDL reduction correlated with PCSK9 and sNOX2-dp delta. In vitro study demonstrated that wPLTs resuspended in plasma from HeFH after PCSK9i treatment induced lower PA and sNOX2-dp release than those obtained using plasma before PCSK9i treatment. This reduction was vanished by adding ox-LDL. ox-LDL-induced PA was blunted by CD36, LOX1, and NOX2 inhibition. Conclusions: PCSK9i treatment reduces PA modulating NOX2 activity and in turn ox-LDL formation in HeFH patients.

Keywords: NOX2; PCSK9; familial hypercholesterolemia; ox-LDL; platelets.

Inflammation contributes to the pathogenesis of neurodegenerative diseases and anti-inflammatory compounds may have a role in prevention or treatment of these pathologies. 4-Methylcoumarins are effective antioxidants with anti-inflammatory properties. In this study, the inhibitory effects of two 4-methylcoumarin derivatives, 7,8-dihydroxy-3-ethoxycarbonylmethyl-4-methylcoumarin (DHEMC) and 7,8-diacetoxy-3-ethoxycarbonylmethyl-4-methylcoumarin (DAEMC) were examined on the inflammatory processes induced by lipopolysaccharide (LPS) in activated primary rat microglial cultures. LPS-induced production of nitric oxide (NO, measured by Griess method) and other pro-inflammatory mediators, thromboxane (TX) B2 and prostaglandin (PG) E2 (both determined by radioimmunoassay (RIA)), as well as tumor necrosis factor (TNF)-α (determined by enzyme-linked immunosorbent assay (ELISA)) were inhibited in the presence of 100 µM DHEMC and DAEMC. DAEMC was able to significantly inhibit NO, TXB2 and TNF-α production also at 50 µM. Both compounds at 100 µM significantly lowered cyclooxygenase-2 (COX-2) protein expression in LPS-stimulated microglial cells measured by Western blot, but only DAEMC showed an inhibitory effect on inducible nitric oxide synthase (iNOS) protein expression at 100 µM. In conclusion, our findings show that 4-methylcoumarin derivatives can modulate inflammatory pathways in microglial cells, probably by acting at the protein expression level.

OBJECTIVE

To observe the thromboxane (TX)B2 and cysteinyl leukotrienes (LTs) levels in the nasal lavage fluid of allergic rhinitis model and to observe the effect of desloratadine on the mediators.

METHODS

In the positive control group, 8-12 week old male or female guinea pigs were intranasal sensitized and challenged with ovalbumin solution. The antihistamine treatment group was treated with desloratadine and the negative control group was sham-sensitized and sham-challenged. The nasal lavage fluid of each group was collected 5 hours after challenge and the levels of TXB2 and LTs in the nasal lavage fluid were measured.

RESULTS

In the positive control group, the TXB2 and LTs levels were the highest of the three groups and the desloratadine treated group had lower level (P < 0.05 and P < 0.01). The negative control showed the lowest level.

CONCLUSIONS

Our study demonstrated that in this model of allergic rhinitis, the levels of TXB2 and LTs in nasal lavage fluid increased dominantly after allergen challenge and desloratadine could inhibit the release of TXB2 and LTs, which implied that the therapeutic mechanism of desloratadine might contribute to the inhibitory effect on TXB2 and LTs production or release in allergic rhinitis subjects.

Calves given 2 subcutaneous inoculations (4 ml, 4.5 weeks apart) of an inactivated bluetongue virus serotype 17 (BTV-17), aluminum hydroxide adjuvant, and cimetidine (600 mg) or levamisole (819 mg, 6 ml) combination were challenge exposed with virulent BTV-17 (2.5 x 10(5) embryo lethal dose) 9 weeks after the 1st inoculation and were monitored for 35 days. Plasma prostaglandins (PG) and thromboxane (Tx) B2 were measured by radioimmunoassay. Histamine was assayed spectrofluorometrically. During the inoculation period (9 weeks from the 1st inoculation to challenge exposure) PGE and histamine increased from base-line concentrations of 34 +/- 3 pg/ml and 1.2 +/- 0.1 ng/ml to 83 +/- 8 pg/ml and 2.0 +/- 0.1 ng/ml, respectively, whereas PGF2 alpha decreased from base-line values of 356 +/- 41 pg/ml to 226 +/- 16 pg/ml. Significant (P less than or equal to 0.05) changes from base-line TxB2 values (110 +/- 7 pg/ml) were not observed during the inoculation period. After challenge exposure, maximum increases were observed in TxB2 (157 +/- 10 pg/ml), PGF2 alpha (713 +/- 93 pg/ml), PGE (140 +/- 30 pg/ml), and histamine (3.6 +/- 0.2 ng/ml) concentrations at 4, 7, 7, and 14 days after challenge exposure, respectively. Concentrations of PGF2 alpha and TxB2 decreased from base-line values to 211 +/- 42 pg/ml and 75 +/- 11 pg/ml, respectively, 21 days after challenge exposure and then returned to base-line values. Significant changes were not observed in plasma concentrations of 6-keto-PGF1 alpha. Results indicate that PG, TxA2, and histamine may be involved in the hypersensitivity reaction to BTV in cattle.

The authors investigated haemostatic parameters of 43 patients with monoclonal gammapathy with principal diagnosis of multiple myeloma (MM-35), non-Hodgkin's lymphoma (NHL-3), M. Waldenström (3) and monoclonal gammapathy of undetermined significance (MGUS-2). Primary haemostasis defect was found in 24 patients. With the exception of 2 thrombocytopenic patients, the defect of aggregation, procoagulant activity and retraction is supposed to be caused by paraprotein. The examination of the 14C 5-HT release and TX B2 synthesis in thrombocytes showed, that platelet activation is unaffected and the paraprotein interferes with interactions of thrombocytes or with coagulation system. In plasma coagulation system explicit abnormalities were found only in thrombin time in 12 patients. The more detailed examination disclosed, that the defect resulted from paraprotein interference with fibrin monomer polymerisation. The thrombin proteolytic activity remained unaffected. In 3 patients shortened euglobulin lysis time was observed. Laboratory haemostasis defect was found in 26 patients (60%), however, the bleeding symptoms manifested in 5 cases (11%) only. The analysis of study results showed, that the most important abnormalities leading to overt bleeding are thrombocytopenia or combined haemostasis defect. Isolated laboratory defects remained silent in most cases.

The authors investigated haemostatic parameters of 43 patients with monoclonal gammapathy with principal diagnosis of multiple myeloma (MM-35), non-Hodgkin's lymphoma (NHL-3), M. Waldenström (3) and monoclonal gammapathy of undetermined significance (MGUS-2). Primary haemostasis defect was found in 24 patients. With the exception of 2 thrombocytopenic patients, the defect of aggregation, procoagulant activity and retraction is supposed to be caused by paraprotein. The examination of the 14C 5-HT release and TX B2 synthesis in thrombocytes showed, that platelet activation is unaffected and the paraprotein interferes with interactions of thrombocytes or with coagulation system. In plasma coagulation system explicit abnormalities were found only in thrombin time in 12 patients. The more detailed examination disclosed, that the defect resulted from paraprotein interference with fibrin monomer polymerisation. The thrombin proteolytic activity remained unaffected. In 3 patients shortened euglobulin lysis time was observed. Laboratory haemostasis defect was found in 26 patients (60%), however, the bleeding symptoms manifested in 5 cases (11%) only. The analysis of study results showed, that the most important abnormalities leading to overt bleeding are thrombocytopenia or combined haemostasis defect. Isolated laboratory defects remained silent in most cases.

We investigated the effects of platelet activating factor (PAF) on the release of thromboxane (Tx) B2 from human granulocytes and platelets. Stimulation of human peripheral whole blood cells by PAF (10(-5) M) resulted in the production of TxB2 (p < 0.05). When human granulocyte suspensions (2.0 x 10(6)/ml) were stimulated by calcium ionophore A23187 (10(-5) M), TxB2 levels in the supernatant fluid increased significantly (p < 0.01). However PAF (10(-5) M) did not increase the levels of TxB2 in granulocyte suspensions. In the presence of cytochalasin B (5 micrograms/ml), PAF (10(-8) M, 10(-7) M, 10(-6) M) did not induce any significant release of TxB2 from granulocytes. The levels of TxB2 in human platelet suspensions were significantly increased by PAF (10(-5) M) stimulation (p < 0.05). These results suggest that PAF induces TxB2 release from human platelets, but it may not stimulate the production of TxB2 in human granulocytes.

1-(3-Benzyloxy-1[E]octenyl)imidazole (CBS-645) is a specific inhibitor of thromboxane synthetase. It inhibits the platelet enzyme in human and rabbit at micromolar concentrations. At a dose of 12.5 mg kg-1 in rabbits, CBS-645 displays a prolonged inhibitory effect on the formation of thromboxane (Tx) B2 induced by blood coagulation in vitro. In human volunteers, an oral dose of 50 mg leads to an average 70% inhibition of TxB2 formation. CBS-645 administered at a dose of 25 mg kg-1 p.o. in the rat, significantly increases bleeding time. In another test in which platelet interaction with the vessel wall is involved, i.e. in vivo platelet deposition onto desendothelialized aorta in the rabbit, the drug shows antithrombotic activity after a single oral administration of 5 mg kg-1. CBS-645 could be of interest in the treatment of the various diseases in which the pathological role of thromboxane A2 is suspected.

Hyperpermeability is a crux of pathogenesis of sudden lung edema in many pulmonary disorders, especially in acute lung injury and adult respiratory distress syndrome (ARDS). Using our modified method for assessment of pulmonary vascular permeability, we observed the effects of xanthine with xanthine oxidase (X-XO) perfused in rat pulmonary artery and the protection of vasoactive intestinal polypeptide (VIP) against the injury of pulmonary vascular permeability. After addition of xanthine oxidase in the perfusate reservoir containing xanthine, 125I-albumin leak index (125IALI) was remarkably increased while peak airway pressure (Paw) was not significantly increased, and perfusion pressure of pulmonary artery (Ppa) and lung wet/dry weight ratio (W/D) were only slightly increased. Xanthine plus xanthine oxidase also increased thromboxane B2 (TX B2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) in the perfusate. Treatment with VIP obviously reduced or totally prevented all signs of injury. Simultaneously, VIP also diminished or abolished the associated generation of arachidonate products. The results indicated that VIP has potent protective activity against injury of pulmonary vascular permeability and may be a physiological modulator of inflammatory damage to vascular endothelium associated with toxic oxygen metabolites.

Hyperpermeability is the crux of pathogenesis of sudden lung edema in many pulmonary disorders, especially in acute lung injury and acute respiratory distress syndrome (ARDS). Using our modified method for assessment of pulmonary vascular permeability, we observed the effects of xanthine with xanthine oxidase (X-XO) perfused in rat pulmonary artery and the protection of vasoactive intestinal polypeptide (VIP) against the injury of pulmonary vascular permeability. After addition of xanthine oxidase in the perfusate reservoir containing xanthine, 125I-albumin leak index (125I-ALI) was remarkably increased while peak airway pressure (Paw) showed no significant increase, and perfusion pressure of pulmonary artery (Ppa) and lung wet/dry weight ratio (W/D) were only slightly increased. Xanthine plus xanthine oxidase also increased thromboxane B2 (TX B2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) in the perfusate. Treatment with VIP obviously reduced or totally prevented all signs of injury. Simultaneously, VIP also diminished or abolished the associated generation of arachidonate products. The results indicated that VIP has potent protective activity against injury of pulmonary vascular permeability and may be a physiological modulator of inflammatory damage to vascular endothelium associated with toxic oxygen metabolites.

The effects of high density lipoprotein (HDL) and low density lipoprotein (LDL) on the formation of 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE), thromboxane (TX) B2 and 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) in washed rabbit platelets were examined. HDL had a powerful inhibitory effect on 12-HETE formation, while it produced only a small increase in TXB2 and HHT formation. LDL did not affect the formation of 12-HETE, TXB2 and HHT. These results suggest that HDL is a selective inhibitor of platelet 12-lipoxygenase and may play a protective role in atherogenesis by preventing the generation of 12-HETE.

To determine whether 5-lipoxygenase products are involved in the development of airway responsiveness and in the infiltration of inflammatory cells into the airway after platelet activating factor (PAF) inhalation, we studied the effect of a selective 5-lipoxygenase inhibitor, AA-861 on PAF-induced airway hyperresponsiveness and on the increase of neutrophil and eosinophil counts in bronchoalveolar lavage fluid (BALF) after PAF inhalation in seven dogs. Airway responsiveness to inhaled methacholine was determined by modified Astograph (7Hz oscillation method). PAF (1000 mu/ml) was delivered as an aerosol, generated from a Devilbiss 646 nebulizer for ten minutes. Airway responsiveness to inhaled methacholine increased significantly 3 hr after PAF inhalation (p less than 0.01). After PAF inhalation, neutrophil and eosinophil counts in BALF increased significantly (p less than 0.01), and the levels of thromboxane (Tx)B2 in BALF also increased (p less than 0.05). Pretreated AA-861 significantly inhibited the increase of airway responsiveness after PAF inhalation (p less than 0.01). The increase of neutrophil and eosinophil counts in BALF after PAF inhalation was also inhibited significantly by pretreated AA-861 (p less than 0.01). The levels of TxB2 in BALF did not change after PAF inhalation following pretreatment with AA-861. These results suggest that 5-lipoxygenase products play important roles in the increase of airway responsiveness and in the infiltration of inflammatory cells into the airway after PAF inhalation in dogs. TxA2 released from inflammatory cells may be involved in the increase of airway responsiveness induced by PAF inhalation.

OBJECTIVE

To observe the effect on infantile allergic cough with Minkeqing oral liquid (Minkeqing) and to study its cell molecular biologic mechanism.

METHODS

The rat model was induced by inhalating ovalbumin; then the effects of Minkeqing on IL-6, IL-8, ET-1, TX-B2 in the blood and the bronchoalveolar lavage fluid (BALF) of the animal model were observed.

RESULTS

Minkeqing could reduce the levels of IL-6,IL-8,ET-1,Tx-B2 in the blood and BALF of the animal model.

CONCLUSIONS

Minkeqing has the significant function of inhibiting the release of inflammatory mediums.

We have recently demonstrated that contact activation of the intrinsic coagulation cascade in vitro is accompanied not only by thromboxane (TX) B2 generation but also by the formation of 5-lipoxygenase-derived cysteinyl-leukotrienes (LT). In our present study we have investigated the effects of the vascular wall on the eicosanoid formation by whole human blood. Incubation of whole human blood in clamped segments of autologous umbilical veins incubated in oxygenated Tyrode solution led to a time-dependent generation of cysteinyl-LT and TXB2 in the blood samples. A clear dissociation in the time-dependent production profiles was observed with cysteinyl-LT practically reaching a plateau phase at 60 min while TXB2 levels increased up to 90 min. In blood samples incubated in glass tubes for 60 min TXB2 production was about 13 times higher and cysteinyl-LT formation only about half as much as in the umbilical vein segments indicating a differential stimulation of both the cyclooxygenase and 5-lipoxygenase pathway of arachidonic acid metabolism in these experiments. By reverse phase HPLC the immunoreactive cysteinyl-LT were identified as a mixture of LTC4, LTD4 and LTE4. Since the data were suggestive of intravascular cysteinyl-LT formation in thrombotic vessels, thrombus specimens from patients with acute deep vein thrombosis of the lower limb were analysed for these compounds by combined reverse phase HPLC and specific radioimmunoassay.(ABSTRACT TRUNCATED AT 250 WORDS)

Apafant (4-(2-chlorophenyl)-9-methyl-2-(3-morpholino-3-oxopropyl)-6H-thieno[3,2- f] [1,2,4]triazolo[4,3-a][1,4] diazepine, CAS 105219-56-5, WEB 2086), as a specific platelet activating factor (PAF) antagonist, inhibited PAF-induced increases of bronchial inflation pressure (delta Pi), pulmonary artery perfusion pressure (delta Pp) and microvascular permeability (wet-to-dry lung weight ratios), dose-dependently, in rats. Apafant also inhibited antigen-induced increase of delta pi, delta Pp and microvascular permeability in passively sensitized rats. Ozagrel also inhibited PAF- and antigen-induced increase of delta Pi, delta Pp and microvascular permeability. Apafant almost completely inhibited the increase of intratracheal pressure and microvascular permeability, but incompletely inhibited the increase of pulmonary artery pressure. At 1 microgram/ml, the effects of ozagrel were almost comparable to that of apafant at the same concentration, but the inhibitory effect on intratracheal pressure was less than that of apafant. Apafant inhibited PAF-induced increase in perfusate of thromboxane (TX) B2 and leukotrine C4/D4E4 (LTs), and antigen-induced increase of TXB2, LTs, PAF and histamine. Ozagrel also inhibited the PAF-induced increase of TXB2, but not the increase of LTs. Apafant inhibited antigen-induced increase of TXB2 and LTs more strongly than PAF-induced increase. The order of inhibitory effects of apafant against generation and release of chemical mediators was TXB2, LTs, PAF and histamine. These findings suggest that TXA2, LTs and PAF may contribute to the increase of intratracheal pressure and microvascular permeability, and histamine may contribute to the increase of vascular resistance in rats. Apafant may inhibit bronchopulmonary responses through PAF receptor antagonism. In addition, apafant can be considered to be useful for the treatment of some allergic diseases when the drug is employed in clinical use.

We have previously demonstrated that clotting of whole human blood in vitro not only triggers the production of thromboxane (TX) B2 but is also accompanied by formation of 5-lipoxygenase-derived cysteinyl-leukotrienes (LT). In order to further characterize the mechanisms leading to activation of the cysteinyl-LT production, we have now investigated the effects of thrombin on cysteinyl-LT as well as TXB2 formation in whole human blood. Addition of exogenous human alpha-thrombin (0.1 - 3.0 U/ml) to whole human blood incubated in vitro led to a concentration- and time-dependently increased release of TXB2 into the serum samples. The serum contents of cysteinyl-LT were, however, not significantly affected. Inactivation of endogenously generated thrombin by inhibitors such as recombinant hirudin (HBW 023, 0.43 - 1.43 microM) or the peptidyl chloromethyl ketone, D-Phe-Pro-Arg-CH2Cl (1.0 - 100 microM) concentration- and time-dependently inhibited the release of TXB2 into the serum or plasma samples. In contrast, however, serum contents of cysteinyl-LT remained unchanged. The identity of immunoreactive material was confirmed by thin-layer chromatography of immunoreactive TXB2 and by reversed phase HPLC of immunoreactive cysteinyl-LT. As expected, washed human platelets stimulated with alpha-thrombin were identified as the major source of TXB2 generation but purified monocytes were also found to release some TXB2 upon alpha-thrombin stimulation. Release of TXB2 by isolated human polymorphonuclear leukocytes (PMN) was negligible in the presence of this stimulus. None of the cells which are known to possess 5-lipoxygenase activity such as PMN or monocytes did release neither cysteinyl-LT nor LTB4 upon stimulation with human alpha-thrombin up to 10 U/ml. These data demonstrate that TXB2 production and cysteinyl-LT formation are differentially activated in spontaneously clotting whole human blood in vitro, the former being dependent on endogenously generated thrombin the latter being dependent on a stimulus yet to be identified.

Contact activation of the intrinsic coagulation cascade in whole human blood in vitro has previously been demonstrated to trigger release of leukotrienes (LT) into serum samples. In our present study we intended to identify the cellular origin of the activated 5-lipoxygenase pathway leading to LT formation under these experimental conditions. Therefore, whole human blood samples incubated for 60 min in vitro were supplemented with Percoll-isolated, 5-lipoxygenase-carrying, autologous blood cells. Surprisingly, exogenously added polymorphonuclear neutrophils (PMN, 5 x 10(6) or 15 x 10(6)/ml) capable of producing cysteinyl-LT in response to ionophore A23187 (1 microM) stimulation, had no effect neither on immunoreactive cysteinyl-LT nor on thromboxane (TX) B2 formation. However, exogenously added mononuclear cells (MNC, 5 x 10(6) or 15 x 10(6)/ml) led to a cell number-dependent increase in cysteinyl-LT generation as did supplementation with peripheral monocytes (PM, 5 x 10(5) or 15 x 10(5)/ml). While MNC enhanced the TXB2 production, PM had no such effect. Incubation of PM (5 x 10(5) or 15 x 10(5)/ml) in recalcified platelet-rich plasma (PRP) induced a cysteinyl-LT formation comparable to that in whole human blood. In contrast to the TXB2 generation, the cysteinyl-LT formation appears to be largely independent from thrombin, since recombinant hirudin (HBW 023, 2 microM), a specific thrombin inhibitor, had no significant effect on the cysteinyl-LT production but nearly completely abolished the TXB2 formation. By reverse phase HPLC the immunoreactive cysteinyl-LT were shown to consist of a mixture of LTC4, LTD4 and LTE4, with LTC4 being the predominant metabolite in all samples studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Eosinophils are thought to be one of the pathophysiologically pivotal cells in atopic-type inflammation. In the present experiments, the in vitro responsiveness to stimuli of eosinophils, which had infiltrated into the airway following intravenous administration of Sephadex G-200 (Sephadex), was mainly studied in non-sensitized and [antigen + Al(OH)3]-sensitized guinea pigs. In sensitized, Sephadex-treated guinea pigs, a large number of eosinophils were found in the bronchoalveolar lavage fluid, whereas a much smaller number of cells were recovered in either non-sensitized or sensitized, Sephadex-untreated animals and a smaller number were recovered in non-sensitized Sephadex-treated animals. The eosinophils from non-sensitized Sephadex-treated guinea pigs released superoxide anion (.O2-) and thromboxane (TX) B2 in response to platelet-activating factor (PAF), leukotriene B4 and Ca ionophore A23187. Either spontaneous or PAF-induced .O2- generation from eosinophils of sensitized, Sephadex-treated guinea pigs was significantly greater than that from non-sensitized animals, while TXB2 release stimulated by any of the above stimuli was not further enhanced by sensitization. These results indicate that active sensitization can change some eosinophil functions and that the functionally altered cells could play a pathophysiological role in atopic inflammation.

BACKGROUND

Preventing anaphylactic reactions as a result of natural rubber latex (NRL) proteins is an important concern in anaesthesia. The clinical relevance of a bacterial/viral filter (Pall B<em>B2</em>5) in preventing sensitization to NRL by inhalation was tested in guinea pigs.

METHODS

Guinea pigs (n=8-10 in each group) were exposed to aerosolized NRL-contaminated cornstarch powder or to NRL in saline for 1 h every day for 2 weeks. The experiments were repeated with a Pall BB2Tx) B2 levels in bronchoalveolar lavage fluid were measured.

RESULTS

After bronchial challenge, the animals exposed to NRL or NRL-contaminated cornstarch with the BB2TxB2 levels were found in the lungs of the guinea pigs, which inhaled NRL or NRL-contaminated cornstarch in the absence of a filter. Animals treated with the filter showed comparable TxB2 levels with those of control.

CONCLUSIONS

The Pall B<em>B2</em>5 filter efficiently protected the guinea pigs from sensitization to NRL. This filter can be used as a complementary measure for avoidance of NRL contact during surgical procedures particularly if the mechanical ventilator apparatus contain NRL devices.

In mild stenosis, coronary blood flow (CBF) was unchanged, thromboxane (TX) B2/6-ketoprostaglandin (PG) F1a ratio rose with no change in PAgT. In critical stenosis, CBF was slightly decreased, PAgT, TXB2 and TXB2/PGF1a ratio rose with cyclical reduction in CBF. In severe stenosis, CBF was markedly decreased; PAgT, TXB2 and TXB2/6-keto-PGF1a ratio rose and 6-keto-PGF1a decreased with cyclical blood flow reduction. Histopathologic examination confirmed the presence of damaged endothelial cell with coronary thrombosis and platelet/fibrin microemboli in critical and severe stenosis. It is concluded that coronary artery stenosis leads to a damage of endothelial cell, which causes an abnormality in platelet function and coronary thrombosis.

Devil's Claw (Harpagophytum procumbens), an herbal product being marketed in Canada and in Europe as a home remedy for the relief of arthritic disease, was investigated in healthy humans on eicosanoid production during spontaneously blood clotting. Volunteers took H. procumbens (daily 4 capsules of 500 mg powder containing 3% of total glucoiridoids) for a period of 21 days. The following are the results (mean (SEM)): before H. procumbens intake, prostaglandin (PG)E2 (ng/ml serum): 2.1 (0.4) (n = 25), thromboxane (TX)B2: 147 (27) (n = 25), 6-keto-PGF1 alpha: 4.4 (0.7) (n = 13), leukotriene (LT)B4: 3.4 (0.4) (n = 25); after intake: PGE2: 3.2 (0.6), TXB2: 143 (24), 6-keto-PGF1 alpha: 4.2 (0.9), LTB4: 3.8 (0.6). Each subject serving as her own control, no statistically significant differences were observed between before and after H. procumbens intake. These results indicate that Devil's Claw lacks, at least in healthy humans and under the selected conditions, the biochemical effects on arachidonic acid metabolism of antiarthritic drugs of the non-steroidal antiinflammatory type.

Floctafenine, a hydroxyquinoline derivative with analgesic properties, is widely used in Thailand and many other countries. The objectives of this study were to evaluate in Thai healthy volunteers: i) the inhibition of whole blood cyclooxygenase(COX)-2 and COX-1 activity by floctafenine and its metabolite floctafenic acid in vitro and ex vivo after dosing with floctafenine; ii) the possible interference of floctafenine administration with aspirin antiplatelet effects. We performed an open-label, cross-over, 3-period study, on 11 healthy Thai volunteers, who received consecutively floctafenine(200mg/TID), low-dose aspirin(81mg/daily) or their combination for 4 days, separated by washout periods. Floctafenine and floctafenic acid resulted potent inhibitors of COX-1 and COX-2 in vitro (floctafenic acid was more potent than floctafenine) showing a slight preference for COX-1. After dosing with floctafenine alone, whole blood COX-1 and COX-2 activities were inhibited ex vivo in a time-dependent fashion which paralleled floctafenic acid plasma concentrations. Aspirin alone inhibited profoundly and persistently platelet COX-1 activity and AA-induced platelet aggregation throughout 24-h dosing interval which was affected by the co-administration of floctafenine. At 24 h after dosing with aspirin and floctafenine, the inhibition of platelet thromboxane(TX)B2 generation and aggregation were significantly(P less than 0.05) lower than that caused by aspirin alone. Therapeutic dosing with floctafenine profoundly inhibited prostanoid biosynthesis through the rapid conversion to floctafenic acid. Floctafenine interfered with the antiplatelet effect of aspirin. Our results suggest that floctafenine should be avoided in patients with cardiovascular disease under treatment with low-dose aspirin.

Platelet inhibition by aspirin is indispensable in the secondary prevention of cardiovascular events. Nevertheless, impaired aspirin antiplatelet effects (high on-treatment platelet reactivity [HTPR]) are frequent. This is associated with an enhanced risk of cardiovascular events. The current gold standard to evaluate platelet hyper-reactivity despite aspirin intake is the light-transmittance aggregometry (LTA). However, pharmacologically, the most specific test is the measurement of arachidonic acid (AA)-induced thromboxane (TX) B2 formation. Currently, the optimal cut-off to define HTPR to aspirin by inhibition of TX formation is not known. Therefore, in this pilot study, we aimed to calculate a TX formation cut-off value to detect HTPR defined by the current gold standard LTA. We measured platelet function in 2,507 samples. AA-induced TX formation by ELISA and AA-induced LTA were used to measure aspirin antiplatelet effects. TX formation correlated nonlinearly with the maximum of aggregation in the AA-induced LTA (Spearman's rho R = 0.7396; 95% CI 0.7208-0.7573, p < 0.0001). Receiver operating characteristic analysis and Youden's J statistics revealed 209.8 ng/mL as the optimal cut-off value to detect HTPR to aspirin with the TX ELISA (area under the curve: 0.92, p < 0.0001, sensitivity of 82.7%, specificity of 90.3%). In summary, TX formation ELISA is reliable in detecting HTPR to aspirin. The calculated cut-off level needs to be tested in trials with clinical end points.