Martine Tencé - Academia.edu (original) (raw)
Papers by Martine Tencé
Proceedings of the National Academy of Sciences of the United States of America, Jan 15, 2002
Cocultures of neurons and astrocytes from the rat striatum were used to determine whether the sti... more Cocultures of neurons and astrocytes from the rat striatum were used to determine whether the stimulation of neuronal receptors could affect the level of intercellular communication mediated by gap junctions in astrocytes. The costimulation of N-methyl-Dasparte (NMDA) and muscarinic receptors led to a prominent reduction of astrocyte gap junctional communication (GJC) in coculture. This treatment was not effective in astrocyte cultures, these cells being devoid of NMDA receptors. Both types of receptors contribute synergistically to this inhibitory response, as the reduction in astrocyte GJC was not observed after the blockade of either NMDA or muscarinic receptors. The involvement of a neuronal release of arachidonic acid (AA) in this inhibition was investigated because the costimulation of neuronal NMDA and muscarinic receptors markedly enhanced the release of AA in neuronal cultures and in cocultures. In addition, both the reduction of astrocyte GJC and the release of AA evoked by NMDA and muscarinic receptor costimulation were prevented by mepacrine, a phospholipase A 2 inhibitor, and this astrocyte GJC inhibition was mimicked by the exogenous application of AA. Metabolites of AA formed through the cyclooxygenase pathway seem to be responsible for the effects induced by either the costimulation of NMDA and muscarinic neuronal receptors or the application of exogenous AA because, in both cases, astrocyte GJC inhibition was prevented by indomethacin. Altogether, these data provide evidence for a neuronal control of astrocytic communication and open perspectives for the understanding of the modalities through which cholinergic interneurons and glutamatergic inputs affect local circuits in the striatum.
Journal of Physiology-paris, 1994
Journal of Mass Spectrometry, 1985
Chemical ionization and fast atom bombardment mass spectra of a series of phospholipids related t... more Chemical ionization and fast atom bombardment mass spectra of a series of phospholipids related to PAF-acether are reported. The usefulness of these methods towards their structural determination is discussed. The mass spectra of sphingomyelin are also examined.
PubMed, Feb 24, 1975
Aspermatogenic seminiferous tubules were incubated in presence of labelled testosterone. This ste... more Aspermatogenic seminiferous tubules were incubated in presence of labelled testosterone. This steroid is converted into androstenedione and 5 alpha-dihydro-testosterone. This finding favours the hypothesis which gives the Sertoli cell an important role in germ cell maturation.
Thrombosis and Haemostasis, 1979
Activation of washed platelets by exogenous phospholipase A 2 (P1A 2) purified from crotalus terr... more Activation of washed platelets by exogenous phospholipase A 2 (P1A 2) purified from crotalus terrificus terrificus venom was studied. PlaEelets were labeled with 14C-serotonin and 51 c hromium and resuspended in Tyrode/ albumin (TA). With 1-5 pg /m l(final conc .) of crotalus P1A2 no direct p latelet alterations were obse rved. These plate l ets , however , we re refrac' tory to collagen-but not to thrombin or HLA-specific antibodies. 10-5 0 pg/ml crotalus P1A 2 rapidly induced p latelet aggregation and rele~e 100 pg/ml crotalus P1A 2 1nduced platelet lysis. P1A 2-induced p latelet alterations were inhibited by EDTA , PGE 1 , ASS and apyrase. Crotapotin , an acid peptid isolated from crotalus venom , fo rms complexes with crotalus P1A2 and specifically inhibits P1A2-induced plate' let alterations. Conclusion: P1A2-i~du ced p latele t alterations are due to liberation of arachidonic acid fr om phospho li p ids of the platelet membrane .inducing prostagland in and =~r o mboxane synthesis. With high concentrations of P1A. breakdown of membra~e phospholipids wi ll lead to platelet lysis .
Journal of Neurochemistry, Nov 13, 2002
In [ 3H]myristicacid-prelabeled Chinese hamster ovary cells stably expressing the rat NK 1 tachyk... more In [ 3H]myristicacid-prelabeled Chinese hamster ovary cells stably expressing the rat NK 1 tachykinin receptor, the selective NK1 agonist [Pro
Molecular and Cellular Endocrinology, May 1, 1989
It therefore appears that the AI1 receptor from human placenta has the same binding and pharmacol... more It therefore appears that the AI1 receptor from human placenta has the same binding and pharmacological properties as other well-known AI1 receptors; by contrast, it is characterized by a significantly higher molecular weight, pointing out that structural differences in AI1 receptors may exist between species.
PubMed, Nov 26, 1979
We have studied the molecular structure of platelet-activating factor" (P.A.F.), a mediator of in... more We have studied the molecular structure of platelet-activating factor" (P.A.F.), a mediator of inflammation obtained from blood leukocytes, macrophages, and platelets themselves. We have semi-synthetized a substance that possesses all the known physicochemical and biological characteristics of P.A.F. from hog leukocytes. This was performed by successive methylation, hydrogenation, and acetylation of lysophosphatidylethanolamine plasmalogen. We therefore propose the following structure for P.A.F.: 1-0-alkyl-2-acetyl-glyceryl-3-phosphorylcholine. This molecular structure is not yet described among the numerous substances capable of inducing platelet aggregation and release.
The Journal of Neuroscience, Feb 1, 1994
Kidney & Blood Pressure Research, 1994
The Journal of Neuroscience, 1992
In cultured striatal astrocytes, 2-chloroadenosine, an adenosine analog resistant to adenosine de... more In cultured striatal astrocytes, 2-chloroadenosine, an adenosine analog resistant to adenosine deaminase, although inactive alone, markedly potentiated the activation of phospholipase C induced by methoxamine, an alpha 1-adrenergic agonist. This effect was suppressed by antagonists of either A1 adenosine or alpha 1-adrenergic receptors. An influx of calcium and two distinct G-proteins are involved in this phenomenon since the potentiating effect of 2-chloradenosine was suppressed in the absence of external calcium or when cells were pretreated with pertussis toxin. In addition, arachidonic acid is likely involved in this potentiating effect. This was shown first by examining the effects of inhibitors of phospholipase A2 or arachidonic metabolism, then by examining the action of arachidonic acid on the production of inositol phosphates in either the presence or absence of methoxamine, and finally by measuring the release of arachidonic acid. The sequential activation of phospholipase...
Proceedings of the National Academy of Sciences, 1991
As previously shown with adenosine, somatostatin, which is ineffective alone, enhanced the alpha ... more As previously shown with adenosine, somatostatin, which is ineffective alone, enhanced the alpha 1-adrenergic-agonist-stimulated production of inositol phosphates in cultured striatal astrocytes. This effect was suppressed in cells pretreated with pertussis toxin. It required external calcium and was selectively antagonized by both mepacrine, an inhibitor of phospholipase A2, and 5,8,11,14-eicosatetraynoic acid, a nonmetabolizable analog of arachidonic acid. In addition, a long-lasting elevation of cytosolic calcium and a release of arachidonic acid were observed only under the combined stimulation of somatostatin and alpha 1-adrenergic receptors. Arachidonic acid could in turn inhibit glutamate uptake into astrocytes, and the resulting external accumulation of glutamate could account for the somatostatin-evoked amplification of the alpha 1-adrenergic-agonist-stimulated hydrolysis of inositol-phospholipids. The effect of somatostatin was indeed reproduced by glutamate or glutamate u...
Journal of Neurochemistry, Nov 18, 2002
In primary cultures of mouse striatal astrocytes prelabeled with [ 3H]myristicacid, endothelin (E... more In primary cultures of mouse striatal astrocytes prelabeled with [ 3H]myristicacid, endothelin (ET)-1 induced a time-dependent formation of [3H]phosphatidic acid and [3H]diacylglycerol. In the presence of ethanol, a production of [3H]phosphatidylethanol was observed, indicating the activation of a phospholipase D (PLD). ET-1 and ET-3 were equipotent in stimulating PLD activity ([050 = 2-5 nM). Pretreatment of the cells with pertussis toxin partially abolished the effect of ET-1, indicating the involvement of a GIG 0 protein. Inhibition of protein kinase C by Ro 31-8220 or down-regulation of the kinase by a long-time treatment with phorbol 1 2-myristate 13-acetate (PMA) totally abolished the ET-1-induced stimulation of PLD. In contrast, a cyclic AMP-dependent process is not involved in the activation of PLD, because the ET-1-evoked formation of [ 3H}phosphatidylethanol was not affected when cells were coincubated with either isoproterenol, 8-bromo-cyclic AMP, or forskolin. Acute treatment with PMA also stimulated PLD through a protein kinase C-dependent process. However, the ET-1 and PMA responses were additive. Furthermore, the ET-1evoked response, contrary to that of PMA, totally depended on the presence of extracellular calcium. These results suggest that at least two distinct mechanisms are involved in the control of PLO activity in striatal astrocytes. Finally, ET-1, ET-3, and PMA also stimulated PLO in astrocytes from the mesencephalon, the cerebral cortex, and the hippocampus.
Agents and actions, Jun 1, 1981
Alkaloids U 0600 Synthesis and Biological Activity of Some Structural Modifications of Pancratist... more Alkaloids U 0600 Synthesis and Biological Activity of Some Structural Modifications of Pancratistatin.-In order to get more insight into the activity issues of pancratistatin, 7-deoxypancratistatin is subjected to replacement or deletion of functionality. The synthesis and evaluation of (IV) and (XI), along with some of the intermediates is carried out. The synthesis of truncated derivative (IV) is based on the interception and adaption of a procedure from the previous synthesis of 7-deoxypancratistatin. The synthesis of the second truncated derivative (XI) is carried out following the strategy employed in the synthesis of 7-deoxypancratistatin. Surprisingly, the ring closure of (IX) occurs without formation of the expected methoxy regioisomer. Derivative (IV), its acetate (III) and the fully hydroxylated derivative (XI) show activities in P388 lines, an order of magnitude lower than that of 7-deoxypancratistatin. Derivative (XI) also displays activity in all human cancer cell lines tested, whereas (IX) lacking the trans-diol unit is inactive in these lines.-(RINNER, U.
Proceedings of the National Academy of Sciences of the United States of America, Dec 1, 1980
Evidence is presented for the simultaneous release of platelet-activating factor (PAF-acether) an... more Evidence is presented for the simultaneous release of platelet-activating factor (PAF-acether) and of its deacetylated derivative (lyso-PAF-acether) from hog leukocytes.
Journal of Neuroscience Research, Jun 1, 2005
Albumin, a blood protein absent from the adult brain in physiological situations, can be brought ... more Albumin, a blood protein absent from the adult brain in physiological situations, can be brought into contact with brain cells during development or, in adult, following breakdown of the blood-brain barrier occurring as a result of local inflammation. In the present study, we show that ovalbumin and albumin induce the release of monocyte chemotactic protein 1 (MCP-1/CCL2) from rat embryonic mixed brain cells. A short-term exposure to ovalbumin during the cell dissociation procedure is sufficient to generate MCP-1 mRNA. A comparable effect is observed when the cells are incubated for 4 hr with ovalbumin or rat albumin, while MCP-1 messengers are barely detectable following bovine albumin exposure. The amount of MCP-1 protein measured in 4 hr-supernatants of albumin-treated cells followed the same albumin-inducing pattern as that of MCP-1 mRNA, while all albumins tested induced MCP-1 protein after a 17 hr-incubation period. The albumin-induced MCP-1 production is significantly inhibited in calphostin C-treated cells, suggesting the implication of a protein kinase C-dependent signaling pathway. This MCP-1-inducing activity is maintained after a lipid extraction procedure but abolished by proteinase K or trypsin treatments of albumin. The MCP-1 secretion following albumin contact with nervous cells could thus interfere, by chemotactic gradient formation, with the brain infiltration program of blood-derived cells during development or brain injury.
International journal of peptide & protein research, Jan 12, 2009
We propose here a biotinyl‐aminohexanoyl‐[Ala1, Phe(4N3)8]angiotensin II analog as a radioiodinat... more We propose here a biotinyl‐aminohexanoyl‐[Ala1, Phe(4N3)8]angiotensin II analog as a radioiodinatable and photoactivatable probe for covalent labeling, detection and isolation of angiotensin receptors. A combination of solid phase and minimum‐protection segment‐coupling strategy using hexafluorophosphate of (benzotriazol‐l‐yloxy)tris(dimethylamino)phosphonium (BOP) as a coupling reagent is proposed for the synthesis of this probe. Optimized yields were obtained by HPLC monitoring of all reactions. A complete n.m.r. study suggests an extended conformation of this molecule, allowing a simultaneous recognition of receptor and avidin. The probe binds with high affinity (Kd= 2 nM) to angiotensin II receptors from rat liver membranes.
British Journal of Haematology, Mar 1, 1983
Summary. The 1‐O‐alkyl‐2‐O‐acetyl‐sn‐glyceryl‐3‐phosphorylcholine (PAF‐acether) aggregates rabbit... more Summary. The 1‐O‐alkyl‐2‐O‐acetyl‐sn‐glyceryl‐3‐phosphorylcholine (PAF‐acether) aggregates rabbit platelets and desensitizes them to a second challenge with the same agonist but not to arachidonic acid. The desensitizing activities of 14 analogues of PAF‐acether were explored with particular attention to the dose‐response dependency of the desensitization process. PAF‐acether was 500‐fold more active than its 1‐O‐acyl analogues. The 2‐lyso PAF‐acether was inactive and the PAF‐acether enantiomer 2000 times less effective than the natural isomer, thus confirming the importance of the presence and steric position of the 2‐acetate group. The desensitizing activities of the 2‐propionyl and the 2‐butyryl analogues were close to that of PAF‐acether. Substituting an ether to an ester bond at the 2‐position indicated that the number of carbon of the 2‐substituant seems more determinant than the nature of the linkage for the desensitizing process. Indeed, the 2‐ethoxy and the 2‐methoxy analogues were 87 and 5000 times less active than PAF‐acether respectively. The presence of methyl groups on the nitrogen base is also critical to desensitize platelets. The desensitizing potency of the tested phospholipids was always identical to their aggregating efficiency. It is suggested that these compounds activate cells through a common mechanism.
Proceedings of the National Academy of Sciences of the United States of America, Jan 15, 2002
Cocultures of neurons and astrocytes from the rat striatum were used to determine whether the sti... more Cocultures of neurons and astrocytes from the rat striatum were used to determine whether the stimulation of neuronal receptors could affect the level of intercellular communication mediated by gap junctions in astrocytes. The costimulation of N-methyl-Dasparte (NMDA) and muscarinic receptors led to a prominent reduction of astrocyte gap junctional communication (GJC) in coculture. This treatment was not effective in astrocyte cultures, these cells being devoid of NMDA receptors. Both types of receptors contribute synergistically to this inhibitory response, as the reduction in astrocyte GJC was not observed after the blockade of either NMDA or muscarinic receptors. The involvement of a neuronal release of arachidonic acid (AA) in this inhibition was investigated because the costimulation of neuronal NMDA and muscarinic receptors markedly enhanced the release of AA in neuronal cultures and in cocultures. In addition, both the reduction of astrocyte GJC and the release of AA evoked by NMDA and muscarinic receptor costimulation were prevented by mepacrine, a phospholipase A 2 inhibitor, and this astrocyte GJC inhibition was mimicked by the exogenous application of AA. Metabolites of AA formed through the cyclooxygenase pathway seem to be responsible for the effects induced by either the costimulation of NMDA and muscarinic neuronal receptors or the application of exogenous AA because, in both cases, astrocyte GJC inhibition was prevented by indomethacin. Altogether, these data provide evidence for a neuronal control of astrocytic communication and open perspectives for the understanding of the modalities through which cholinergic interneurons and glutamatergic inputs affect local circuits in the striatum.
Journal of Physiology-paris, 1994
Journal of Mass Spectrometry, 1985
Chemical ionization and fast atom bombardment mass spectra of a series of phospholipids related t... more Chemical ionization and fast atom bombardment mass spectra of a series of phospholipids related to PAF-acether are reported. The usefulness of these methods towards their structural determination is discussed. The mass spectra of sphingomyelin are also examined.
PubMed, Feb 24, 1975
Aspermatogenic seminiferous tubules were incubated in presence of labelled testosterone. This ste... more Aspermatogenic seminiferous tubules were incubated in presence of labelled testosterone. This steroid is converted into androstenedione and 5 alpha-dihydro-testosterone. This finding favours the hypothesis which gives the Sertoli cell an important role in germ cell maturation.
Thrombosis and Haemostasis, 1979
Activation of washed platelets by exogenous phospholipase A 2 (P1A 2) purified from crotalus terr... more Activation of washed platelets by exogenous phospholipase A 2 (P1A 2) purified from crotalus terrificus terrificus venom was studied. PlaEelets were labeled with 14C-serotonin and 51 c hromium and resuspended in Tyrode/ albumin (TA). With 1-5 pg /m l(final conc .) of crotalus P1A2 no direct p latelet alterations were obse rved. These plate l ets , however , we re refrac' tory to collagen-but not to thrombin or HLA-specific antibodies. 10-5 0 pg/ml crotalus P1A 2 rapidly induced p latelet aggregation and rele~e 100 pg/ml crotalus P1A 2 1nduced platelet lysis. P1A 2-induced p latelet alterations were inhibited by EDTA , PGE 1 , ASS and apyrase. Crotapotin , an acid peptid isolated from crotalus venom , fo rms complexes with crotalus P1A2 and specifically inhibits P1A2-induced plate' let alterations. Conclusion: P1A2-i~du ced p latele t alterations are due to liberation of arachidonic acid fr om phospho li p ids of the platelet membrane .inducing prostagland in and =~r o mboxane synthesis. With high concentrations of P1A. breakdown of membra~e phospholipids wi ll lead to platelet lysis .
Journal of Neurochemistry, Nov 13, 2002
In [ 3H]myristicacid-prelabeled Chinese hamster ovary cells stably expressing the rat NK 1 tachyk... more In [ 3H]myristicacid-prelabeled Chinese hamster ovary cells stably expressing the rat NK 1 tachykinin receptor, the selective NK1 agonist [Pro
Molecular and Cellular Endocrinology, May 1, 1989
It therefore appears that the AI1 receptor from human placenta has the same binding and pharmacol... more It therefore appears that the AI1 receptor from human placenta has the same binding and pharmacological properties as other well-known AI1 receptors; by contrast, it is characterized by a significantly higher molecular weight, pointing out that structural differences in AI1 receptors may exist between species.
PubMed, Nov 26, 1979
We have studied the molecular structure of platelet-activating factor" (P.A.F.), a mediator of in... more We have studied the molecular structure of platelet-activating factor" (P.A.F.), a mediator of inflammation obtained from blood leukocytes, macrophages, and platelets themselves. We have semi-synthetized a substance that possesses all the known physicochemical and biological characteristics of P.A.F. from hog leukocytes. This was performed by successive methylation, hydrogenation, and acetylation of lysophosphatidylethanolamine plasmalogen. We therefore propose the following structure for P.A.F.: 1-0-alkyl-2-acetyl-glyceryl-3-phosphorylcholine. This molecular structure is not yet described among the numerous substances capable of inducing platelet aggregation and release.
The Journal of Neuroscience, Feb 1, 1994
Kidney & Blood Pressure Research, 1994
The Journal of Neuroscience, 1992
In cultured striatal astrocytes, 2-chloroadenosine, an adenosine analog resistant to adenosine de... more In cultured striatal astrocytes, 2-chloroadenosine, an adenosine analog resistant to adenosine deaminase, although inactive alone, markedly potentiated the activation of phospholipase C induced by methoxamine, an alpha 1-adrenergic agonist. This effect was suppressed by antagonists of either A1 adenosine or alpha 1-adrenergic receptors. An influx of calcium and two distinct G-proteins are involved in this phenomenon since the potentiating effect of 2-chloradenosine was suppressed in the absence of external calcium or when cells were pretreated with pertussis toxin. In addition, arachidonic acid is likely involved in this potentiating effect. This was shown first by examining the effects of inhibitors of phospholipase A2 or arachidonic metabolism, then by examining the action of arachidonic acid on the production of inositol phosphates in either the presence or absence of methoxamine, and finally by measuring the release of arachidonic acid. The sequential activation of phospholipase...
Proceedings of the National Academy of Sciences, 1991
As previously shown with adenosine, somatostatin, which is ineffective alone, enhanced the alpha ... more As previously shown with adenosine, somatostatin, which is ineffective alone, enhanced the alpha 1-adrenergic-agonist-stimulated production of inositol phosphates in cultured striatal astrocytes. This effect was suppressed in cells pretreated with pertussis toxin. It required external calcium and was selectively antagonized by both mepacrine, an inhibitor of phospholipase A2, and 5,8,11,14-eicosatetraynoic acid, a nonmetabolizable analog of arachidonic acid. In addition, a long-lasting elevation of cytosolic calcium and a release of arachidonic acid were observed only under the combined stimulation of somatostatin and alpha 1-adrenergic receptors. Arachidonic acid could in turn inhibit glutamate uptake into astrocytes, and the resulting external accumulation of glutamate could account for the somatostatin-evoked amplification of the alpha 1-adrenergic-agonist-stimulated hydrolysis of inositol-phospholipids. The effect of somatostatin was indeed reproduced by glutamate or glutamate u...
Journal of Neurochemistry, Nov 18, 2002
In primary cultures of mouse striatal astrocytes prelabeled with [ 3H]myristicacid, endothelin (E... more In primary cultures of mouse striatal astrocytes prelabeled with [ 3H]myristicacid, endothelin (ET)-1 induced a time-dependent formation of [3H]phosphatidic acid and [3H]diacylglycerol. In the presence of ethanol, a production of [3H]phosphatidylethanol was observed, indicating the activation of a phospholipase D (PLD). ET-1 and ET-3 were equipotent in stimulating PLD activity ([050 = 2-5 nM). Pretreatment of the cells with pertussis toxin partially abolished the effect of ET-1, indicating the involvement of a GIG 0 protein. Inhibition of protein kinase C by Ro 31-8220 or down-regulation of the kinase by a long-time treatment with phorbol 1 2-myristate 13-acetate (PMA) totally abolished the ET-1-induced stimulation of PLD. In contrast, a cyclic AMP-dependent process is not involved in the activation of PLD, because the ET-1-evoked formation of [ 3H}phosphatidylethanol was not affected when cells were coincubated with either isoproterenol, 8-bromo-cyclic AMP, or forskolin. Acute treatment with PMA also stimulated PLD through a protein kinase C-dependent process. However, the ET-1 and PMA responses were additive. Furthermore, the ET-1evoked response, contrary to that of PMA, totally depended on the presence of extracellular calcium. These results suggest that at least two distinct mechanisms are involved in the control of PLO activity in striatal astrocytes. Finally, ET-1, ET-3, and PMA also stimulated PLO in astrocytes from the mesencephalon, the cerebral cortex, and the hippocampus.
Agents and actions, Jun 1, 1981
Alkaloids U 0600 Synthesis and Biological Activity of Some Structural Modifications of Pancratist... more Alkaloids U 0600 Synthesis and Biological Activity of Some Structural Modifications of Pancratistatin.-In order to get more insight into the activity issues of pancratistatin, 7-deoxypancratistatin is subjected to replacement or deletion of functionality. The synthesis and evaluation of (IV) and (XI), along with some of the intermediates is carried out. The synthesis of truncated derivative (IV) is based on the interception and adaption of a procedure from the previous synthesis of 7-deoxypancratistatin. The synthesis of the second truncated derivative (XI) is carried out following the strategy employed in the synthesis of 7-deoxypancratistatin. Surprisingly, the ring closure of (IX) occurs without formation of the expected methoxy regioisomer. Derivative (IV), its acetate (III) and the fully hydroxylated derivative (XI) show activities in P388 lines, an order of magnitude lower than that of 7-deoxypancratistatin. Derivative (XI) also displays activity in all human cancer cell lines tested, whereas (IX) lacking the trans-diol unit is inactive in these lines.-(RINNER, U.
Proceedings of the National Academy of Sciences of the United States of America, Dec 1, 1980
Evidence is presented for the simultaneous release of platelet-activating factor (PAF-acether) an... more Evidence is presented for the simultaneous release of platelet-activating factor (PAF-acether) and of its deacetylated derivative (lyso-PAF-acether) from hog leukocytes.
Journal of Neuroscience Research, Jun 1, 2005
Albumin, a blood protein absent from the adult brain in physiological situations, can be brought ... more Albumin, a blood protein absent from the adult brain in physiological situations, can be brought into contact with brain cells during development or, in adult, following breakdown of the blood-brain barrier occurring as a result of local inflammation. In the present study, we show that ovalbumin and albumin induce the release of monocyte chemotactic protein 1 (MCP-1/CCL2) from rat embryonic mixed brain cells. A short-term exposure to ovalbumin during the cell dissociation procedure is sufficient to generate MCP-1 mRNA. A comparable effect is observed when the cells are incubated for 4 hr with ovalbumin or rat albumin, while MCP-1 messengers are barely detectable following bovine albumin exposure. The amount of MCP-1 protein measured in 4 hr-supernatants of albumin-treated cells followed the same albumin-inducing pattern as that of MCP-1 mRNA, while all albumins tested induced MCP-1 protein after a 17 hr-incubation period. The albumin-induced MCP-1 production is significantly inhibited in calphostin C-treated cells, suggesting the implication of a protein kinase C-dependent signaling pathway. This MCP-1-inducing activity is maintained after a lipid extraction procedure but abolished by proteinase K or trypsin treatments of albumin. The MCP-1 secretion following albumin contact with nervous cells could thus interfere, by chemotactic gradient formation, with the brain infiltration program of blood-derived cells during development or brain injury.
International journal of peptide & protein research, Jan 12, 2009
We propose here a biotinyl‐aminohexanoyl‐[Ala1, Phe(4N3)8]angiotensin II analog as a radioiodinat... more We propose here a biotinyl‐aminohexanoyl‐[Ala1, Phe(4N3)8]angiotensin II analog as a radioiodinatable and photoactivatable probe for covalent labeling, detection and isolation of angiotensin receptors. A combination of solid phase and minimum‐protection segment‐coupling strategy using hexafluorophosphate of (benzotriazol‐l‐yloxy)tris(dimethylamino)phosphonium (BOP) as a coupling reagent is proposed for the synthesis of this probe. Optimized yields were obtained by HPLC monitoring of all reactions. A complete n.m.r. study suggests an extended conformation of this molecule, allowing a simultaneous recognition of receptor and avidin. The probe binds with high affinity (Kd= 2 nM) to angiotensin II receptors from rat liver membranes.
British Journal of Haematology, Mar 1, 1983
Summary. The 1‐O‐alkyl‐2‐O‐acetyl‐sn‐glyceryl‐3‐phosphorylcholine (PAF‐acether) aggregates rabbit... more Summary. The 1‐O‐alkyl‐2‐O‐acetyl‐sn‐glyceryl‐3‐phosphorylcholine (PAF‐acether) aggregates rabbit platelets and desensitizes them to a second challenge with the same agonist but not to arachidonic acid. The desensitizing activities of 14 analogues of PAF‐acether were explored with particular attention to the dose‐response dependency of the desensitization process. PAF‐acether was 500‐fold more active than its 1‐O‐acyl analogues. The 2‐lyso PAF‐acether was inactive and the PAF‐acether enantiomer 2000 times less effective than the natural isomer, thus confirming the importance of the presence and steric position of the 2‐acetate group. The desensitizing activities of the 2‐propionyl and the 2‐butyryl analogues were close to that of PAF‐acether. Substituting an ether to an ester bond at the 2‐position indicated that the number of carbon of the 2‐substituant seems more determinant than the nature of the linkage for the desensitizing process. Indeed, the 2‐ethoxy and the 2‐methoxy analogues were 87 and 5000 times less active than PAF‐acether respectively. The presence of methyl groups on the nitrogen base is also critical to desensitize platelets. The desensitizing potency of the tested phospholipids was always identical to their aggregating efficiency. It is suggested that these compounds activate cells through a common mechanism.