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Biomedical subjects

J Devin

Publications and source records attributed to J Devin.

At least 19 recordsLinked to original sources
PubMed1998

Tirapazamine with cisplatin in patients with advanced non-small-cell lung cancer: a phase II study.

PURPOSE: A phase II study was conducted to evaluate the safety and efficacy of tirapazamine combined with cisplatin for the treatment of patients with advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Forty-four patients with stage IIIB/IV NSCLC were treated with a combination of tirapazamine and cisplatin. Patients received tirapazamine 260 mg/m2 administered intravenously over 2 hours, followed 1 hour later by cisplatin 75 mg/m2 administered over an additional hour, repeated every 21 days. The duration of therapy was meant to be limited to four cycles for nonresponders and eight cycles for responders. RESULTS: Ten of 44 patients (23%) showed a partial response. The estimated median survival for all patients was 37 weeks. Toxicities were treatable and included grade 3 nausea or vomiting (25%), fatigue (27.3%), and muscle cramps (4.5%). No dose reductions were necessary. CONCLUSION: The results show that tirapazamine can safely be added to cisplatin. Both the median survival and response rate observed strongly suggest that tirapazamine with cisplatin is more active than cisplatin alone.

Adult↗
PubMed1996

Mutational analysis of Hsp90 alpha dimerization and subcellular localization: dimer disruption does not impede "in vivo' interaction with estrogen receptor.

The molecular chaperone Hsp90 has been found ubiquitously as a predominantly cytoplasmic dimer. By interacting with cytoplasmic or nuclear proteins such as pp60v-src or steroid receptors, Hsp90 helps its targets to become competent for full biological activity. Mutational deletion analysis of some properties of chicken Hsp90 alpha was undertaken after transient transfection of the constructs in COS7 cells. First, Hsp90 mutants were analyzed for their ability to behave as cytosolic dimers. We confirmed that the C-terminal Hsp90 region (amino acids 446-728) was sufficient for dimerization, and found that deletion of three small subregions in the 200 C-terminal residues precluded Hsp90 dimer formation. Moreover, we demonstrated that the N-terminal region of the protein (1-442) was not involved in dimerization. Second, the subcellular localization of the wild-type (WT) protein and mutants was analyzed by specific immunodetection and confocal microscopy. Most of the mutants were cytoplasmic like Hsp90WT, a nuclear localization being barely detectable in the WT protein or in mutants with a C-terminal truncation equal to or shorter than 286 residues. Surprisingly a mutant encoding the N-terminal region (1-285) was nuclear localized. In addition, the in vivo interaction between the cytoplasmic Hsp90 and the nuclear ER was documented after coexpression of both proteins in the same cells: some Hsp90 was shifted into the nucleus via its interaction with ER. From an analysis of dimeric or monomeric cytoplasmic Hsp90 mutants, we found that disruption of Hsp90 dimer did not systematically impede its interaction with ER. Finally, Hsp90WT and cytoplasmic mutants were tested for their ability to rescue from lethality a yeast strain deleted of both Hsp90 genes. Interestingly, the delta 661-677 mutant that showed an impaired dimerization but interacted with ER was able to confer viability, while the mutant deleted of the 30 C-terminal residues (NC6) was monomeric, did not confer viability and did not interact with ER. We therefore suggest that Hsp90 properties analyzed here are not necessarily interdependent.

Animals↗
PubMed1995

The health impact of economic sanctions.

Embargoes and sanctions are tools of foreign policy. They can induce a decline in economic activity in addition to reducing imports and untoward health effects can supervene, especially among older persons and those with chronic illnesses. Often, violations of the rights of life, health, social services, and protection of human dignity occur among innocent civilians in embargoed nations. This paper examines the effects of embargoes and sanctions against several nations, and calls for studies to determine ways in which economic warfare might be guided by the rule of humanitarian international law, to reduce the effects on civilians. It suggests that the ability to trade in exempted goods and services should be improved, perhaps by establishing uniform criteria and definitions for exemptions, operational criteria under which sanctions committees might function, and methods for monitoring the impact of sanctions on civilian populations in targeted states, particularly with regard to water purity, food availability, and infectious-disease control. Prospective studies are advocated, to generate the data needed to provide better information and monitoring capacity than presently exists.

Delivery of Health Care↗
PubMed1994

In vivo functional protein-protein interaction: nuclear targeted hsp90 shifts cytoplasmic steroid receptor mutants into the nucleus.

In target tissue extracts, heat shock protein hsp90 has been found associated to all unliganded steroid receptors. Modulation of important functions of these receptors, including prevention of DNA binding and optimization of transcriptional activity, has been attributed to hsp90. However no unequivocal in vivo demonstration of interaction between receptors and hsp90 has been presented. We targeted chicken hsp90, a mainly cytoplasmic protein, with the nucleoplasmin nuclear localization signal (90NLS). After transfection into COS-7 cells, 90NLS was found in the nucleus with specific immunofluorescence and confocal microscopy techniques. A human glucocorticosteroid receptor mutant devoid of NLS sequence was also expressed in COS-7 cells and found exclusively cytoplasmic. Coexpression of 90NLS and of the cytoplasmic human glucocorticosteroid receptor mutant led to complete nuclear localization of the receptor, indicating its piggyback transport by 90NLS and thus physical and functional interaction between the two proteins in the absence of hormone. The same nuclear localization was obtained after cotransfection of 90NLS and a cytoplasmic rabbit progesterone receptor mutant. Finally, coexpression of wild-type rabbit progesterone receptor (nuclear) and wildtype hsp90 (cytoplasmic) into COS-7 cells provoked partial relocalization of hsp90 into the nucleus. These experiments lay the groundwork on which to study hsp90 as a chaperone, regulating activities of steroid receptors and possibly participating in their nuclear-cytoplasmic shuttling.

Amino Acid Sequence↗
PubMed1993

Cloning of chicken hsp90 beta: the only vertebrate hsp90 insensitive to heat shock.

The cloning of chicken hsp90 beta, reported here, supports the hypothesis that the hsp90 alpha and beta genes are the result of a gene duplication event that occurred at the time of the emergence of vertebrates. Avian hsp90 beta mRNA is not inducible by thermal stress contrary to the mouse and human hsp90 alpha and beta mRNAs. Moreover, hsp90 beta mRNA level is not increased by mitogenic stimuli, like serum or insulin, which induce hsp90 alpha mRNA. Different functions and regulations of hsp90 alpha and beta will be probably more easily understood in the avian species than in higher vertebrates.

Amino Acid Sequence↗
PubMed1991

Growth factors acting via tyrosine kinase receptors induce HSP90 alpha gene expression.

Hsp90 is a heat-shock protein constitutively expressed in most cells. Besides regulation by thermal stress, the expression of hsp90 is also positively regulated by developmental and mitogenic stimuli. The effect of serum and insulin on protein and hsp90 alpha-mRNA levels has been studied in the chicken hepatoma cell line DU249. The culture of cells in serum-free medium resulted in a decrease of hsp90 alpha-mRNA level. A transient increase was observed at 6-9 h after serum restimulation. The expression of hsp90 gene was also increased by insulin alone in a dose-dependent manner and was maximum between 6 and 9 h treatment. The insulin induced increase of hsp90 alpha-mRNA was suppressed by cycloheximide (10 micrograms/ml) but not by an inhibitor of DNA synthesis, demonstrating that this induction requires protein neosynthesis. In serum starved cells, other growth factors (IGF1, EGF and bFGF) showed a positive effect on hsp90 alpha-mRNA level which took place before DNA synthesis with the same time-course as that of insulin. With PDGF, the induction of hsp90 alpha-mRNA occurred earlier. The time interval between the maximum of hsp90 alpha-mRNA induction and that of DNA synthesis was the same for all growth factors studied. From these results, we conclude that growth factors acting via tyrosine kinase receptors up-regulate hsp90 alpha-mRNA level in a DNA synthesis independent manner, possibly in late G1.

Blood↗
PubMed1988

Covalent stabilization of the nontransformed chick oviduct cytosol progesterone receptor by chemical cross-linking.

The nontransformed forms of the chick oviduct cytosol progesterone receptor of sedimentation coefficient approximately 8 S (8S-PR) are heterooligomers including one hormone binding molecule, either B, approximately 110,000, or A, approximately 79,000, and two non-hormone binding subunits recently identified as heat-shock protein Mr approximately 90,000 (hsp 90) [Renoir, J. M., Buchou, T., Mester, J., Radanyi, C., & Baulieu, E. E. (1984) Biochemistry 23, 6016-6023]. In the crude cytosol, bisimidates reacted under mild conditions and gave rise to complexes, binding progesterone and reacting with BF4, an anti-hsp 90 monoclonal antibody. These complexes have a sedimentation coefficient of 8.4 S and Rs of 8.1 nm in the presence of 0.4 M KCl and in the absence of molybdate ions, i.e., in conditions that would transform non-cross-linked 8S-PR to Rs approximately 5 nm forms of approximately 4-S sedimentation coefficient. All bisimidates tested, of an effective reagent length between 0.73 and 1.09 nm, gave comparable results in the cytosol prepared with or without molybdate ions, confirming that the latter were not responsible for the formation of the cross-linked 8S complexes. It was found that the dimethyl pimelimidate cross-linked 8S-PR was more resistant to inactivating conditions, urea, or heat treatment than the non-cross-linked 8S-PR. The 8S-PR cross-linked in the cytosol was purified by affinity chromatography in the absence of molybdate ions. After purification, it also reacted with the monoclonal antibody BF4 and had the same Rs (8.0 nm), sedimentation coefficient (approximately 8.5 S), and thus Mr (approximately 290,000) as the original cytosol.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

1H NMR configurational correlation for retro-inverso dipeptides: application to the determination of the absolute configuration of "enkephalinase" inhibitors. Relationships between stereochemistry and enzyme recognition.

A stereospecific synthesis of thiorphan [N-[2(RS)-(mercaptomethyl)-1-oxo-3-phenylpropyl]glycine] and retro-thiorphan [3-[[1(RS)-(mercaptomethyl)-2-phenylethyl]amino]-3-oxopropanoic acid], two highly potent inhibitors of enkephalinase, a neutral endopeptidase involved in enkephalin metabolism, is reported. Due to a rapid isomerization process, derivatives of retro-thiorphan, which contains a 2-substituted malonyl moiety, cannot be separated by classical methods. However, a separation of the diastereoisomeric mixtures of these retro-thiorphan derivatives was achieved by HPLC. The absolute configuration of each isomer was determined by using an NMR configurational correlation. The inhibitory potency of the various inhibitors indicates that, in the thiorphan series, the affinity for enkephalinase is independent of the stereochemistry of the 2-(mercaptomethyl)-1-oxo-3-phenylpropyl moiety. In contrast, in the retro-thiorphan series a 100-fold difference in the inhibitory activity of the two enantiomers is observed. This indicates that there are large differences in the conformational behavior of the two series of inhibitors at the active site of the enzyme.

Amino Acids, Sulfur↗
PubMed1986

Enkephalin-degrading dipeptidylaminopeptidase: characterization of the active site and selective inhibition.

The enkephalins are degraded in vitro by three types of metallopeptidases including a dipeptidylaminopeptidase (DAP) which releases Tyr-Gly. In order to test the physiological significance of this enzyme in enkephalin metabolism, a membrane-bound DAP from porcine brain was purified. The structural characteristics of the active site of this enzyme were studied using several enkephalin-related fragments as substrates and various peptides as inhibitors. The active site possesses an anionic moiety able to interact with the ammonium group of the substrate and four hydrophobic subsites S2, S1, S1', S2' surrounding the metal-containing catalytic site. This porcine brain enzyme shows the same characteristics as a partially purified DAP from rat brain. Potent inhibitors of both enzymes were obtained with compounds interacting with either the S1', S2', or S1, S2 parts of the active site and containing a hydroxamate of an N-acyl-N-hydroxy amino group as the metal-chelating agent. The compounds synthesized to bind the S1', S2' subsites, such as HN(OH)--CO--CH2--CH(CH2 phi)-CONH--CH(CH2 phi)--COOH, behave as highly potent and mixed inhibitors of both DAP (Ki = 2.5 nM) and enkephalinase (Ki = 0.3 nM). In contrast, Tyr-Phe-NHOH, designed to interact with S2,S1 subsites through its positively charged Tyr as the P2 component, is a highly potent (Ki = 9 nM) and selective DAP inhibitor. The ability of Tyr-Phe-NHOH to protect, in vivo, endogenous enkephalins was evaluated using the hot plate test with mice. The intracerebroventricular injection of Tyr-Phe-NHOH alone (0.17 mumol, 60 micrograms) does not significantly modify the jump latency time as compared to the control. The effect of the association of Tyr-Phe-NHOH (0.17 mumol, 60 micrograms), bestatin (0.16 mumol, 50 micrograms) and thiorphan (0.20 mumol, 50 micrograms) is not statistically different from that produced by bestatin (0.16 mumol) plus thiorphan (0.20 mumol). Likewise, the effect of bestatin (50 micrograms) or thiorphan (25 micrograms) is not significantly modified by intracerebroventricular co-administration of increasing concentrations of Tyr-Phe-NHOH. These results seem to indicate that the DAP does not play a major role in enkephalin metabolism, at least at the supraspinal level.

Animals↗
PubMed1985

In vitro and in vivo effects of kelatorphan on enkephalin metabolism in rodent brain.

Biologically relevant assays were used to compare the potency of kelatorphan (N-[3(R)-[(hydroxyamino)carbonyl]-2-benzyl-1-oxopropyl]-L-alanine) as inhibitor of the peptidase-induced metabolism of enkephalins to that of bestatin, a non-specific inhibitor of aminopeptidase and thiorphan, a highly potent blocker of the neutral endopeptidase (EC 3.4.24.11) designated as enkephalinase. Kelatorphan almost completely inhibited the formation of the three metabolites [3H]Tyr, [3H]Tyr-Gly and [3H]Tyr-Gly-Gly produced by incubation of [3H][Tyr1,Met5]enkephalin with rat striatal slices. Co-administered with [Met5]enkephalin in mouse brain, kelatorphan was able to prevent by 80% the degradation of the exogenous peptide. Moreover, a mixture of thiorphan (1 microM) and bestatin (20 microM) or kelatorphan alone (20 microM) induced a 2.2 to 2.5-fold increase in endogenous [Met5]enkephalin overflow after evoked depolarization of superfused rat striatal slices. In this assay, kelatorphan was the only compound to increase by 63% the basal level of released [Met5]enkephalin. Kelatorphan was about 100 times less potent than bestatin to inhibit the total rat striatal aminopeptidases, but as efficient (IC50 = 4 X 10(-7) M) as bestatin to inhibit a minor aminopeptidase activity resembling aminopeptidase M. Therefore the reported enhanced analgesic potency of kelatorphan with regard to the association of bestatin and thiorphan is very likely related to its ability to almost completely inhibit enkephalin-degrading enzymes (including the Tyr-Gly releasing peptidase) and to its better selectivity for the biologically relevant aminopeptidase M. Kelatorphan would be a valuable probe, preferable to the association of bestatin and thiorphan, to investigate the physiological functions regulated by a phasic enkephalinergic activity.

Aminopeptidases↗
PubMed1985

Binding of the bidentate inhibitor [3H]HACBO-Gly to the rat brain neutral endopeptidase "enkephalinase".

The synthesis and binding properties to rat brain tissue of the enkephalinase inhibitor [3H] N-[(R,S)-3-hydroxyaminocarbonyl-2-benzyl-1-oxopropyl]-glycine ([3H]HACBO-Gly, 45 Ci/mmole) is reported. [3H]HACBO-Gly binding to membranes from various rat brain tissue is saturable (KD = 0.4 +/- 0.05 nM) and linearly related to the amount of tissue. Non specific binding is less than 15% of total binding at the KD concentration. The regional distribution of [3H]HACBO-Gly binding and enkephalinase activity are closely correlated with highest levels in striatum and substantia nigra. The efficiency of inhibitors of various peptidases (thiorphan, captopril, bestatin ...) to inhibit [3H]HACBO-Gly binding or enkephalinase activity are similar. These results indicate that [3H]HACBO-Gly binds selectively to enkephalinase. This compound should help to clarify the localization of the enzyme in the CNS.

Animals↗
PubMed1985

Kelatorphan: a full inhibitor of enkephalin degrading enzymes. Biochemical and pharmacological properties, regional distribution of enkephalinase in rat brain by use of a tritiated derivative.

New potent inhibitors of enkephalin degrading enzymes were obtained by synthesis of compounds bearing a bidentate group. Among these bidentates, Kelatorphan, N-[(R)-3-(N-hydroxy)-carboxamido-2-benzylpropanoyl]-L-alanine, is in vitro a full inhibitor of enkephalinase, dipeptidylaminopeptidase and aminopeptidase. In vivo Kelatorphan (i.c.v. administered in mice) prevents exogenous enkephalin from peptidase degradation. The analgesic effect of Kelatorphan is at least equal to that of the association of bestatin and thiorphan. An analogue of Kelatorphan was tritiated and was used as a specific marker of enkephalinase. Thus the distribution of enkephalinase in rat brain was studied: striatum corpus and substantia nigra were particularly labelled.

Aminopeptidases↗
PubMed1985

New bidentates as full inhibitors of enkephalin-degrading enzymes: synthesis and analgesic properties.

New compounds were designed to fully inhibit the in vitro metabolism of enkephalins, ensured by three different metallopeptidases. For this purpose, bidentate ligands as hydroxamate and N-hydroxy-N-formylamino groups were selected as highly potent metal coordinating agents and introduced on Phe-Gly and Phe-Ala related structures. Compounds corresponding to the general formula HC(O)N(OH)CH2CH(CH2Ph)CONHCH2COOH (compound 7) and HN(OH)C(O)CH2CH(CH2Ph)CONHCH(R)COOH (compound 11, R = H; compound 13, R = CH3) behave as full inhibitors of the three enzymes, with IC50's in the nanomolar range for enkephalinase, from 0.3 microM to 1 nM for dipeptidylaminopeptidase, and in the micromolar range for a biologically relevant aminopeptidase. Two diastereoisomers of the most active inhibitor 13 were separated by HPLC and their stereochemistry was assigned by 1H NMR spectroscopy. Both isomers were efficient as enkephalinase blockers, but only the RS isomer, designated kelatorphan, was able to strongly inhibit aminopeptidase and dipeptidylaminopeptidase. Intracerebroventricular injection in mice of these mixed inhibitors, especially kelatorphan, led to naloxone reversible analgesic responses (hot-plate test) that were slightly better than those produced by a mixture of thiorphan and bestatin, two potent inhibitors of enkephalinase and aminopeptidase, respectively. Kelatorphan was also more efficient in potentiating the analgesia induced by a subanalgesic dose of Met-enkephalin. All these results support a physiological role in pain transmission for enkephalinase and a probably synaptic aminopeptidase M.

Aminopeptidases↗
PubMed1984

Bidentate peptides: highly potent new inhibitors of enkephalin degrading enzymes.

Three series of bidentates bearing an hydroxamic or an N-Acyl-N-hydroxy amino group on structures related to Phe-Gly or Phe-Ala exhibit strong inhibitory potency against purified enkephalinase with IC50 values in the 4 to 15 nM range. As with thiol-containing inhibitors, such as thiorphan, the most active compounds are those in which a methylene spacer separates the benzyl P1' moiety from the Zn coordinating residue. Formation of a bidentate complex with the metal enzyme is clearly demonstrated by a loss of potency of three order of magnitude following the removal of one component of the bidentate group. All the compounds studied are unable to interact with angiotensin converting enzyme (IC50 greater than 10,000 nM). Moreover, compounds of the general formula HONHCO-CH2-CH(CH2 phi)-CONH-CH(R)-COOH belonging to the most active series of enkephalinase blockers (IC50 approximately 4 nM) behave also as highly potent and competitive inhibitors (IC50 approximately 10 nM) of a Tyr-Gly releasing dipeptidylaminopeptidase purified from rat brain. The pure steroisomer [(R)-3-(N-hydroxy)carboxamido-2-benzylpropanoyl]-L-alanine designated kelatorphan, exhibits also a relatively good inhibitory potency against aminopeptidases (IC50 approximately 10 microM) and can be considered as the first virtually complete inhibitor of enkephalin metabolism. This very interesting property of inhibiting all three enzymes of enkephalin metabolism could enhance the required selectivity for a possible clinical use of these inhibitors as new analgesic and psychoactive drugs.

Aminopeptidases↗
PubMed1984

Synthesis of peptides related to the prosegment of mouse submaxillary gland renin precursor: an approach to renin inhibitors.

The complete sequence of the structural gene coding for mouse submaxillary gland renin was recently reported and the amino acid sequence of preprorenin was deduced. This sequence includes a 45-amino acid peptide that corresponds to the prosegment of the renin precursor. To investigate whether peptides related to the renin prosegment are able to inhibit renin activity, we have synthesized four peptides having the following structures: Arg-Ile-Pro-OMe, butyloxycarbonyl(Boc)-Leu-Lys-Lys-Met-Pro-OMe, Boc-Arg-Ile-Pro-Leu-Lys-Lys-Met-Pro-OMe, and Boc-Glu-Arg-Ile-Pro-Leu-Lys-Lys-Met-Pro-OMe (corresponding to amino acids 12-14, 15-19, 12-19, and 11-19, respectively, of the renin prosegment). All four peptides were found to inhibit the activity of pure mouse submaxillary renin on a porcine synthetic tetra-decapeptide in vitro, and the most potent inhibitors exhibited IC50 values in the micromolar range. Enzymatic kinetic studies carried out using peptide 15-19 showed an uncompetitive or a mixed type of inhibition with a Ki value of 2.3 X 10(-6) M at 37 degrees C in 0.5 M citrate/phosphate buffer (pH 6.0).

Amino Acid Sequence↗
PubMed1983

Mycotic aortic aneurysms. A reappraisal.

Mycotic aneurysms are uncommon but not rare lesions with potential for catastrophic hemorrhage or sepsis. They have been ascribed to bacterial endocarditis and, when present in the aorta, were termed "inevitably fatal" as recently as 1967. A 15-year review of the English-language literature on mycotic aneurysms showed that arterial trauma, concurrent sepsis, and depressed host immunity have become the cardinal "risk factors" in the development of these lesions. Conventional treatment of mycotic aortic aneurysms usually includes aortic ligation, aneurysmal excision, and extra-anatomic bypass grafting. Nevertheless, four of our patients with well-localized mycotic aortic aneurysms survived three to 54 months (mean, 40 months) after aortic excision and in situ prosthetic graft restoration of aortic continuity. This experience suggests that mycotic aortic aneurysms can be successfully treated, frequently by in situ grafting, if diagnosis and treatment are timely and aggressive.

Adult↗