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D Reynaud

Publications and source records attributed to D Reynaud.

At least 19 recordsLinked to original sources
PubMed2006

Hepoxilin analogs, potential new therapeutics in disease.

We have chemically synthesized several stable analogs of the naturally occurring hepoxilins, 12-LO products derived from arachidonic acid, which we found to have promising actions in a variety of test systems of disease. The analogs, PBTs, afford chemical and biological stability to the hepoxilin molecule. This article reviews some of our latest observations with the PBTs in the areas of inflammation (inhibition of the bleomycin-evoked lung fibrosis in mice in vivo), platelet aggregation (antagonism of the thromboxane receptor in human platelets in vitro) and thrombosis (inhibitors in vivo), and cancer (apoptosis of the human leukemia cell line, K562 in vitro and in vivo). The demonstration that the PBTs are active in vivo suggests that they can serve as a platform for their further development as novel therapeutics in disease.

8,11,14-Eicosatrienoic Acid↗
PubMed2002

The hepoxilin analog PBT-3 inhibits heparin-activated platelet aggregation evoked by ADP.

We have previously shown that PBT-3, a stable synthetic analog of hepoxilins, inhibits the aggregation of human platelets in vitro evoked by collagen through inhibition of thromboxane A(2) formation and action on the TP receptor. We now show that PBT-3 is capable of potently inhibiting the second phase of aggregation evoked by ADP in both washed human platelets and platelet-rich plasma (PRP), a phase associated with thromboxane formation. Aspirin blocks this second phase as well; so does the thromboxane receptor antagonist SQ 29,548. When ADP-evoked aggregation in PRP is activated by heparin through an enhancement of thromboxane formation, PBT-3, aspirin as well as SQ 29,548 block this activation through different mechanisms. These data confirm the inhibitory action of PBT-3 on aggregation of human platelets through inhibition of both thromboxane formation and blockade of thromboxane receptor action and suggest that this family of compounds may be useful in the treatment of thrombotic disorders in combination with heparin.

8,11,14-Eicosatrienoic Acid↗
PubMed2002

[Two cases of polyarteritis nodosa with a good prognosis?].

INTRODUCTION: Polyarteritis nodosa is a systemic necrotizing vasculitis that may become serious, even with no usual poor prognosis factors. EXEGESIS: We report two cases of polyarteritis nodosa with negative histology, starting only with an extensive necrosis of the extremities. The treatment, associating corticosteroids and, secondarily, immunosuppressors, did not prevent a bilateral half-leg amputation for the two patients. In the first case the disease stabilized, but in the second one, it worsened, leading to death within 2 years. CONCLUSION: This clinical aspect of the disease is unusual and should be identified because of its bad prognosis. It might benefit from a treatment from the outset associating corticosteroids and immunosuppressors, even with no usual bad prognosis factors.

Adrenal Cortex Hormones↗
PubMed2001

Improved high-performance liquid chromatographic method for the combined analysis of phospholipase, lipoxygenase and cyclooxygenase activities.

We report herein an improved method for the high-performance liquid chromatographic separation and analysis of eicosanoids formed during the stimulation of human platelets in vitro with collagen. Since the products of interest, excepting arachidonic acid, contain hydroxyl groups (one to several), our method involves the conversion of the hydroxyl groups into acetates (pyridine/acetic anhydride) after derivatization with anthryl diazomethane (ADAM) rendering the compounds with much decreased polarity for separation on a reversed-phase column. This procedure is superior to that involving ADAM esters only, i.e. with free hydroxyl groups, as it leads to the excellent separation of the desired compounds from each other and from extraneous peaks observed due to the ADAM reagent and sharpens the peak of thromboxane. We have successfully applied the method to investigate the formation of thromboxane B2 and 12-hydroxyheptadecatrienoic acid (HHT) (products of cyclooxygenase and thromboxane A2 synthase), 12-hydroxyeicosatetraenoic acid (12-HETE, a 12-lipoxygenase product) and arachidonic acid (AA, product of phospholipase A2) formed during the in vitro aggregation of human platelets induced by collagen. A correlation between the inhibition of aggregation by aspirin and thromboxane/HHT formation was observed. All four compounds can be chromatographed in a single run. We employed prostaglandin B1 (PGB1) as internal reference standard to quantify the products. The method is useful to investigate selectivity of drugs which may affect either or all of these enzyme pathways at the same time.

Blood Platelets↗
PubMed2001

Novel platelet antiaggregating substances.

We describe herein a novel action of four stable analogs of the hepoxilins. These analogs inhibit to different degrees, the aggregation of washed human platelets evoked by collagen. One of the analogs, PBT-3, is particularly effective with an IC(50) = 8 x 10(-7) M. The other analogs are about 5-fold less active, but all analogs are about 500-fold more active than the native hepoxilins. The PBT analogs inhibit the collagen-enhanced formation of thromboxane A(2) and HHT but do not affect the formation of 12-HETE or the release of arachidonic acid except at doses higher than those needed to block platelet aggregation. These results demonstrate that these novel compounds may have potential for development into drugs in the treatment of thromboxane-mediated cardiovascular disease.

Arachidonic Acids↗
PubMed2001

[Peri-aortic fibrosis: unusual case of jaundice].

Periaortic fibrosis is defined as the development of aortic perianeuvrysmal fibrosis either resulting from a focal inflammatory reaction or a self-perpetuating process. Compression of neighboring organs is a possible complication. Bile duct obstruction is exceptional.

Aorta, Abdominal↗
PubMed2000

[Association between polymyositis and hepatitis C infection. Treatment-related difficulties].

INTRODUCTION: Chronic hepatitis C virus infection is often associated with various auto-immune disorders. We report four cases of an association between polymyositis and hepatitis C virus infection. The course and the difficulties of therapy are discussed. EXEGESIS: Among 510 consecutive patients infected by viral hepatitis C, we report four cases of polymyositis. Corticosteroids increased serum alanine aminotransferase levels in two cases, leading to severe liver injury in one patient. Worsening of polymyositis under interferon-alpha therapy was observed in one case. Clinical and biological stability were reported in another case. Aggravation of polymyositis with severe muscle weakness and dyspnea occurred in two patients after disruption of interferon-alpha treatment. Intravenous gamma globulins subsequently improved their condition, without biological worsening of viral hepatitis. CONCLUSION: These observations suggest an association between hepatitis C virus infection and polymyositis. Because corticosteroids can induce adverse effects in the liver, intravenous gamma globulins could be used for the treatment of this particular form of polymyositis.

Antiviral Agents↗
PubMed1999

Formation of 14,15-hepoxilins of the A(3) and B(3) series through a 15-lipoxygenase and hydroperoxide isomerase present in garlic roots.

We report herein for the first time the formation by freshly grown garlic roots and the structural characterization of 14,15-epoxide positional analogs of the hepoxilins formed via the 15-lipoxygenase-induced oxygenation of arachidonic acid. These compounds are formed through the combined actions of a 15(S)-lipoxygenase and a hydroperoxyeicosatetraenoic acid (HPETE) isomerase. The compounds were formed when either arachidonic acid or 15-HPETE were used as substrates. Both the "A"-type and the "B"-type products are formed although the B-type compounds are formed in greater relative quantities. Chiral phase high performance liquid chromatography analysis confirmed the formation of hepoxilins from 15(S)- but not 15(R)-HPETE, indicating high stereoselectivity of the isomerase. Additionally, the lipoxygenase was of the 15(S)-type as only 15(S)-hydroxyeicosatetraenoic acid was formed when arachidonic acid was used as substrate. The structures of the products were confirmed by gas chromatography-mass spectrometry of the methyl ester trimethylsilyl ether derivatives as well as after characteristic epoxide ring opening catalytically with hydrogen leading to dihydroxy products. That 15(S)-lipoxygenase activity is of functional importance in garlic was shown by the inhibition of root growth by BW 755C, a dual cyclooxygenase/lipoxygenase inhibitor and nordihydroguaiaretic acid, a lipoxygenase inhibitor. Additional biological studies were carried out with the purified intact 14(S), 15(S)-hepoxilins, which were investigated for hepoxilin-like actions in causing the release of intracellular calcium in human neutrophils. The 14,15-hepoxilins dose-dependently caused a rise in cytosolic calcium, but their actions were 5-10-fold less active than 11(S), 12(S)-hepoxilins derived from 12(S)-HPETE. These studies provide evidence that 15(S)-lipoxygenase is functionally important to normal root growth and that HPETE isomerization into the hepoxilin-like structure may be ubiquitous; the hepoxilin-evoked release of calcium in human neutrophils, which is receptor-mediated, is sensitive to the location within the molecule of the hydroxyepoxide functionality.

8,11,14-Eicosatrienoic Acid↗
PubMed1999

The GM2 activator protein, a novel inhibitor of platelet-activating factor.

The GM2 activator protein is required as a substrate-specific cofactor for beta-hexosaminidase A to hydrolyze GM2 ganglioside. The GM2 activator protein reversibly binds and solubilizes individual GM2 ganglioside molecules, making them available as substrate. Although GM2 ganglioside is the strongest binding ligand for the activator protein, it can also bind and transport between membranes a series of other glycolipids, even at neutral pH. Biosynthetic studies have shown that a large portion of newly synthesized GM2 activator molecules are not targeted to the lysosome, but are secreted and can then be recaptured by other cells through a carbohydrate independent mechanism. Thus, the GM2 activator protein may have other in vivo functions. We found that the GM2 activator protein can inhibit, through specific binding, the ability of platelet activating factor (PAF) to stimulate the release of intracellular Ca2+ pools by human neutrophils. PAF is a biologically potent phosphoacylglycerol. Inhibitors for PAF's role in the pathogenesis of inflammatory bowel disease and asthma have been sought as potential therapeutic agents. The inherent stability and protease resistance of the small, monomeric GM2 activator protein, coupled with the ability to produce large quantities of the functional protein in transformed bacteria, suggest it may serve as such an agent.

Calcium↗
PubMed1999

Hepoxilin signaling in intact human neutrophils: biphasic elevation of intracellular calcium by unesterified hepoxilin A3.

We have previously shown that the methyl ester of hepoxilin A3 causes a receptor-induced rise in intracellular calcium through the release from intracellular stores in suspended human neutrophils. The corresponding free acid was devoid of activity. We now report that the action of the free acid form of hepoxilin A3 is dependent on the type of vehicle used, i.e. it is active in releasing calcium when used in an ethanol vehicle but not in DMSO. The methyl ester is equally active in either vehicle. The pattern of calcium release between the free acid and the methyl ester is qualitatively different. Both compounds show a biphasic pattern, i.e. an initial rapid phase followed by a slow decline in calcium levels but never reaching pre-hepoxilin A3 baseline levels. The methyl ester appears slightly more potent in the initial phase of calcium release than the free acid (methyl = 188+/-14 S.D., free acid = 135+/-11 S.D. nM, P < 0.0005). Both compounds appear to reach the same calcium levels at the plateau of the second prolonged phase (methyl = 88+/-8 S.D., free acid = 107+/-15 S.D. nM, not significant). Lanthanum chloride (an inhibitor of calcium influx) interfered with the second phase of the curve causing calcium levels to return to normal pre-hepoxilin levels for both compounds. Addition of lanthanum chloride prior to the hepoxilin addition or carrying out the experiments in calcium-free medium, eliminated the second phase completely, with the calcium peak returning rapidly to normal baseline levels, suggesting that the second phase is due to calcium influx. Again the methyl ester is more active than the free acid (methyl, 189+/-12; free acid, 145+/-6 S.D. nM, P<0.005). Additional experiments with tritium-labelled methyl ester of hepoxilin A3 demonstrated that the compound is hydrolyzed into the free acid intracellularly. These experiments demonstrate that DMSO interacts with hepoxilin free acid, interfering with its entry into the cell while ethanol does not. Once inside the cell, hepoxilin interacts with its own receptor to release calcium rapidly from stores, but it also causes a more prolonged influx of calcium from the extracellular milieu.

8,11,14-Eicosatrienoic Acid↗
PubMed1999

In vivo stimulation of 12(S)-lipoxygenase in the rat skin by bradykinin and platelet activating factor: formation of 12(S)-HETE and hepoxilins, and actions on vascular permeability.

In this study we set out to investigate whether the inflammatory agents, bradykinin (BK) and platelet activating factor (PAF), affect the lipoxygenase pathway in rat skin in vivo and whether the main products so formed may be involved in the inflammatory actions of these agents. In vitro preparations of epidermis were also investigated to determine whether lipoxygenases are stimulated by these agents. We also investigated the actions of arachidonic acid and 12(S)-HPETE as substrates for the lipoxygenases. Our results indicated that 12-lipoxygenase is actively and selectively stimulated in a dose-dependent way in both preparations by the administration of BK and PAF; the main product, 12-HETE, was shown by chiral analysis to be exclusively of the S-configuration, indicating that 12(S)-lipoxygenase was present in the rat skin and was stimulated by these inflammatory agents. Hepoxilins were also formed but to a lesser extent in both in vivo and in vitro preparations. In separate experiments, 12(S)-HETE administered intradermally on its own (40 ng/site), increased vascular permeability as also seen with bradykinin (100 ng/site) and PAF (10 ng/site). However, unlike previously observed with hepoxilin A3 administration, 12(S)-HETE did not stimulate the action of BK on vascular permeability, suggesting that the two compounds may have different mechanisms of action to enhance inflammation. These observations suggest that the vascular permeability and plasma extravasation observed with both inflammatory agents (BK and PAF) may be mediated at least in part through the activation of 12(S)-lipoxygenase, resulting in enhanced formation of 12(S)-HETE which causes acute inflammation.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1999

Biochemical, hemodynamic, and vascular evidence concerning the free radical hypothesis of nitrate tolerance.

Tolerance to nitroglycerin (NTG) may be due to increased superoxide anion production. Hemodynamic parameters and biochemical markers of free radical production were measured in 20 healthy male subjects at baseline, 3 h after acute transdermal NTG (0.6 mg/h), and after 5 days of continuous therapy. Transdermal NTG therapy was continued, and 2 days later all subjects received 2 g of oral vitamin C, or placebo, in a double-blind, randomized, crossover fashion. In another study of eight male subjects, forearm plethysmography was used to assess the venous responses to sublingual NTG at baseline, after 5 days of sustained transdermal NTG therapy (0.6 mg/h), and after 2 g of oral vitamin C or placebo. Systolic blood pressure decreased in response to acute transdermal NTG therapy but returned to normal after sustained NTG therapy, indicating the development of tolerance. The venous volume responses to sublingual NTG were significantly diminished after sustained therapy with transdermal NTG. Plasma lipid peroxidation products, 8-iso-PGF2 alpha, and vitamin C were unchanged by acute and sustained therapy with transdermal NTG. Vitamin C failed to restore either the hemodynamic or venous effects of NTG. These results do not support the hypothesis that nitrate therapy and tolerance is associated with increased free radical production.

Administration, Cutaneous↗
PubMed1999

The hepoxilins. A review.

This manuscript reviews the literature on hepoxilins to date. It affords a review of the structures, nomenclature, biosynthesis, catabolism and biological actions of the hepoxilins and some of their chemical analogs. Some unpublished data are also presented. The primary biological action of the hepoxilins appears to relate to their ability to release calcium from intracellular stores through a receptor-mediated action. The receptor is intracellular, and appears to be G-protein coupled. The conversion of hepoxilin into its omega-hydroxy catabolite has recently been demonstrated through the action of an omega-hydroxylase. This enzyme is different from that which oxidizes leukotriene B4, as the former activity is lost when the cell is disrupted, while leukotriene B4-catabolic activity is recovered in both the intact and disrupted cell. Additionally, hepoxilin catabolism is inhibited by CCCP, a mitochondrial uncoupler, while leukotriene catabolism is unaffected. As hepoxilins cause the translocation of calcium from intracellular stores in the endoplasmic reticulum to the mitochondria, it is speculated that hepoxilin omega-oxidation takes place in the mitochondria, and the omega-oxidation product facilitates accumulation of the elevated cytosolic calcium by the mitochondria. The biological activity of stable analogs of the hepoxilins is also described which inhibit the calcium-releasing actions of neutrophil inflammatory mediators.

8,11,14-Eicosatrienoic Acid↗