Glial vascular endothelial growth factor overexpression in rat brainstem under tolerable hypoxia: evidence for a central chemosensitivity.

The ventilatory response to hypoxia is mediated by peripheral inputs arising from the arterial chemoreceptors. In their absence, hypoxic adaptation can be achieved, possibly as a result of central cellular reorganization. To study this reorganization, we used chemodenervated rats to investigate the expression and localization of vascular endothelial growth factor (VEGF) in the brainstem. VEGF is a target gene of hypoxia-inducible factor (HIF) that is responsible for the morphofunctional remodeling induced by hypoxia. Intact and chemodenervated rats were subjected to normoxia or hypoxia for 6 hr (10% O(2) in N(2)). VEGF protein was quantified in micropunches of brainstem tissue. Only chemodenervated animals showed an increased VEGF expression in response to hypoxia, whereas, in normoxia, VEGF expression was not modified by chemodenervation. The same hypoxic condition was repeated for 8 days before immunocytochemical staining with anti-VEGF; antiglial fibrillary acidic protein (GFAP), a marker of astrocytes; and anti-rat endothelial cell antigen-1 (anti-RECA-1) that recognizes endothelial cells. Confocal analysis showed a cellular colocalization of GFAP and VEGF, indicating that VEGF was overexpressed predominantly in astrocytes. Increased RECA-1 immunolabeling indicated an enhanced angiogenesis in chemodenervated rats subjected to hypoxia. These results indicate that glial cells and the vascular network contribute to the brainstem remodeling. The peripheral chemodenervation reveals a central O(2) chemosensitivity involving a cascade of gene expression triggered by hypoxia, which in intact animals may act synergically with peripheral chemosensory inputs.

DNA cleavage by hydroxy-salicylidene-ethylendiamine-iron complexes.

Bis(hydroxy)salen.Fe complexes were designed as self-activated chemical nucleases. The presence of a hy-droxyl group on the two salicylidene moieties serve to form a hydroquinone system cooperating with the iron redox system to facilitate spontaneous formation of free radicals. We compared the DNA binding and cleaving properties of the ortho -, meta- and para -(bishydroxy) salen.Fe complexes with that of the corresponding chelate lacking the hydroxyl groups. DNA melting temperature studies indicated that the para complex exhibits the highest affinity for DNA. In addition, this para compound was considerably more potent at cleaving supercoiled plasmid DNA than the regio-isomeric ortho - and meta -hydroxy-salen.Fe complexes, even in the absence of a reducing agent, such as dithiothreitol used to activate the metal complex. The DNA cleaving activity of the para isomer is both time and concentration dependent and the complexed iron atom is absolutely essential for the sequence uniform cleavage of DNA. From a mechanistic point of view, electron spin resonance measurements suggest that DNA contributes positively to the activation of the semi-quinone system and the production of ligand radical species responsible for subsequent strand scission in the absence of a reducing agent. The para -hydroxy-salen.Fe complex has been used for detecting sequence-specific drug-DNA interactions. Specific binding of Hoechst 33258 to AT sequences and chromomycin to GC sequences were shown. The para -bis(hydroxy)salen.Fe derivative complements the tool box of footprinting reagents which can be utilised to produce efficient cleavage of DNA.

Randomized, double-blind, crossover, placebo-controlled comparison of propranolol and betaxolol in the treatment of neuroleptic-induced akathisia.

OBJECTIVE: Beta-blocking agents, particularly propranolol, are considered effective in the treatment of neuroleptic-induced akathisia, but considerable controversy exists about the involved receptor subtype(s). The authors conducted a randomized, controlled trial comparing the effects of propranolol and betaxolol to determine whether central beta 1-adrenoceptor blockade is sufficient to correct neuroleptic-induced akathisia. METHOD: The subjects were 19 patients whose neuroleptic-induced akathisia responded to 20 mg/day of propranolol and subsequently reemerged during a placebo washout period. They were randomly assigned to propranolol (20 or 40 mg/day) or betaxolol (10 or 20 mg/day) and, after another placebo period, were switched to the second beta blocker. RESULTS: There was no significant difference in the antiakathisia effects of propranolol and betaxolol. CONCLUSIONS: The lack of difference between propranolol and betaxolol suggests that beta 1-adrenoceptor blockade is sufficient to improve neuroleptic-induced akathisia. The results of this explanatory study need therapeutic confirmation.

Comparison of propranolol, sotalol, and betaxolol in the treatment of neuroleptic-induced akathisia.

In earlier open studies, beta-blockers were found to be effective in the treatment of neuroleptic-induced akathisia. In the present study, 16 patients with severe neuroleptic-induced akathisia successively received low doses of three beta-blockers--propranolol, sotalol, and betaxolol. There was rapid and complete improvement in seven of 16 patients (and partial improvement in three patients) treated with betaxolol. The efficacy of propranolol and betaxolol and failure of sotalol in treating neuroleptic-induced akathisia suggest a central mechanism of action.

Antioxidant properties of hydroxy-flavones.

The antioxidant properties of 24 hydroxy-flavones were evaluated. Results show that 2',3',4'-OH substitution on the B ring plays a crucial role in radical scavenger activity in the DPPH assay and in the inhibitory effect on pereoxydation of tissue lipids in the MDA test. The formation of stable radicals for this type of compounds has been studied by ESR. In addition, it has been found that 7-hydroxy-flavones are potent competitive inhibitors of xanthine oxidase. It is proposed that the C-7 OH of flavones may take the place of the C-2 or C-6 OH of xanthine in the active site of the enzyme. A C-4' OH or C-4' OMe substitution on the 7-hydroxy flavones is not favourable to a fit in the active site. The 2',3',4'-trihydroxy-flavones inhibited XO by another process, which remains to be determined. In summary, this study provides evidence that hydroxy-flavones exhibit interesting antioxidant properties expressed either by the capacity to scavenge free radicals (for 2',3',4'-trihydroxy-flavones) or to competitively inhibit xanthine oxidase (for 7-hydroxy-flavones). These compounds may be drug candidates for treating pathologies related to free radical oxidation.

Antioxidant actions of ovothiol-derived 4-mercaptoimidazoles: glutathione peroxidase activity and protection against peroxynitrite-induced damage.

4-Mercaptoimidazoles derived from the naturally occurring antioxidants, ovothiols, were tested for their glutathione peroxidase-like (GSH Px-like) activity and protection against peroxynitrite-induced damage. All the thiol compounds displayed similar significant GSH Px-like activities, which are however weaker than that of the reference compound, ebselen. The inhibitions of the peroxynitrite-dependent oxidation of Evans blue dye and dihydrorhodamine 123 showed that the thiol compounds substituted on position 5 of the imidazole ring were nearly as effective as ebselen while the C-2 substituted ones were less effective. Both assays corroborate the large superiority of mercaptoimidazoles over glutathione as inhibitors of peroxynitrite-dependent oxidation.

Antioxidant properties of natural hydroquinones from the marine colonial tunicate Aplidium californicum.

Antioxidant prenylated hydroquinones and non active chromene or chroman extracted from the marine colonial tunicate Aplidium californicum have been studied in order to throw some light on their biological activity. It has been found that the active compounds inhibit superoxide anion production in rat alveolar macrophages and in the xanthine/xanthine oxidase system. The antioxidant activity may be ascribed rather to a direct reaction of the superoxide anion with the hydroquinones than to an enzymatic inhibition or a membrane signal transfer. A physiological activity close to that of alpha tocopherol can be considered.

Scavenger and antioxidant properties of ten synthetic flavones.

To study the effect of the hydroxyl groups on biological activities of flavones, we synthesized 10 polyhydroxyflavones with varied substitution patterns. The abilities of the 10 compounds to act as radical scavengers were investigated using chemiluminescence in two biological models: the xanthine/xanthine oxidase system and the oxidative burst of rat alveolar macrophages. Stable radical formation was observed by electron spin resonance (ESR) spectroscopy. We found that the presence of the pyrogallol moiety in the B component of flavones gave rise to radical scavenger activity and that C-6 substituted hydroxyl group may also provide the basis for biological activity. Furthermore, compounds with a hydroxyl at C-7 position appeared to be xanthine oxidase inhibitors. One particular compound exhibited radical scavenger activity and xanthine oxidase inhibition. This type of compound should prove to be useful in the treatment of ischemia, for which both properties were required.

Synthesis and antitumor properties of an anthraquinone bisubstituted by the copper chelating peptide Gly-Gly-L-His.

A new molecule 4 [(GGH-DAE)2DHQ] associating the 1,4,5,8-tetrahydroxyanthraquinone ring (DHQ) of the antitumor drug mitoxantrone (2), two diaminoethylene chains (DAE), and the metal-chelating peptide Gly-Gly-His (GGH) has been synthesized. Such a molecule presents characteristics able to induce antitumor activity: compound 4 intercalates into DNA as measured by delta Tm, fluorescence quenching, and viscometry; ESR studies demonstrate that several types of Cu complexes are formed depending on pH; and the production of free radicals, as evidenced by spin-trapping, is enhanced by 4. In vitro, in leukemia cells L1210 and mammary cells MCF7, 4 is slightly less cytostatic than mitoxantrone, but substantially less toxic. In vivo, in leukemia P388 on mice, a T/C value of 230 is obtained at 25 mg/kg, higher than the one of mitoxantrone, which is toxic at the same dose.

Subcellular distribution of a nitroxide spin-labeled netropsin in living KB cells. Electron paramagnetic resonance and sequence specificity studies.

A nitroxide spin-labeled netropsin was studied by EPR spectroscopy with respect to its uptake and localization in living KB cells. Whereas the drug was taken up readily, there was relatively little drug in the cytoplasm, but a significant concentration of the drug in the cell nucleus. The EPR signal in the latter site corresponded to a relatively freely rotating radical. The drug exhibited good intracellular stability up to 25 hr. While a delta Tm of 24 degrees between the spin-labeled netropsin and calf thymus DNA confirmed strong binding, the absence of any DNA elongation by viscometry was consistent with nonintercalative exterior binding which was confirmed to be minor groove specific by binding of the agent to T4 DNA with a delta Tm of 17.5 degrees. The sequence specificity of the DNA binding of the spin-labeled drug was confirmed by methidiumpropyl-EDTA (MPE) footprinting on a fragment of pBR322 DNA to be very similar to that of the parent netropsin, i.e. selective for AT-rich sites, with minor differences of protection afforded by introduction of the nitroxide label.

4-Mercaptoimidazoles derived from the naturally occurring antioxidant ovothiols 2. Computational and experimental approach of the radical scavenging mechanism.

The radical-scavenging mechanism of fourteen 4-mercaptoimidazoles, derived from the natural family of ovothiols, was studied via a QSAR approach, cyclic voltammetry, ESR and NMR spectroscopy. A significant correlation was found between the DPPH scavenging abilities of test compounds and thermodynamic parameters like overall ease of disulphide formation. The production of a disulphide compound via thiyl radical formation is proposed. Upon DPPH scavenging, hydrogen abstraction from thiols yields transient short-lived thiyl radicals, which were characterised by ESR and rapidly dimerise to form a disulphide compound. Cyclic voltammetry showed that the best DPPH scavengers exhibit low oxidation potentials for their oxidation to disulphides.

4-Mercaptoimidazoles derived from the naturally occurring antioxidant ovothiols 1. Antioxidant properties.

4-Mercaptoimidazoles derived from the naturally occurring family of antioxidants, the ovothiols, were assayed for their antioxidant properties. These compounds are powerful HOCl scavengers, more potent than the aliphatic thiol N-acetylcysteine. They react slowly with hydrogen peroxide with second order rate constants of 0.13-0.89 M(-1)s(-1). Scavenging of hydroxyl radical occurs at a diffusion-controlled rate (k=2.0-5.0 x 10(10)M(-1)s(-1)) for the most active compounds, which are also able to inhibit copper-induced LDL peroxidation. The combination of radical scavenging and copper chelating properties may explain the inhibitory effects on LDL peroxidation. Two molecules of mercaptoimidazole can chelate a copper ion and form a square planar complex detected by EPR. Compounds bearing an electron-withdrawing group on position 2 of the imidazole ring are the most potent antioxidant molecules in this series.

ESR evidence for the oxidative cleavage of gentisic acid in basic aqueous solution.

The oxidative cleavage of 2,5-dihydroxybenzoic acid (gentisic acid), presumably into maleylpyruvate in basic aqueous solution has been shown by ESR spectra of semiquinonic radicals bearing a methylenic group. One of these radicals has been unambiguously attributed to 2,4,5-trihydroxyphenylacetic acid semiquinonic radical. The formation of an hydroxylated homogentisic acid from gentisic acid (a metabolite of aspirin) is of particular importance in the treatment of alkaptonuria and related inflammatory arthritis.

Antioxidant activities of dihydroxylated salicylic acid derivatives.

The ability of hydroxylated metabolites of salicylic acid to scavenge reactive oxygen species and to inhibit arachidonic acid metabolism was investigated. The tested trihydroxybenzoic acids (THBAs) were potent scavengers of hydroxyl and superoxide anion radicals produced by Fenton reaction and xanthine/xanthine oxidase system or activated macrophages respectively. In the same tests, salicylic acid possessed moderate O2(-) and low OH'scavenging activities. Our results demonstrate that adding two hydroxyl groups to salicylic acid strongly increases the reactive oxygen species (ROS) scavenging activities. Adding two hydroxyl groups at position 4 and 5 (2,4,5-THBA) affords the most active ROS scavenging activity probably due to the ortho unsubstituted catechol moiety. In fact, we can consider that the ROS scavenging properties of salicylic acid are essentially due to its metabolic products such as 2,3- and 2,5-DHBAs, catechol and also to THBAs.

Redox chemistry of complexes of nickel(II) with some biologically important peptides in the presence of reduced oxygen species: an ESR study.

The reactions between some Ni(II) oligopeptides (Gly-His-Lys, (Gly)4, Asp-Ala-His-Lys, Gly-Gly-His, beta Ala-His, and serum albumin) and reduced oxygen species have been characterized by spin-trapping experiments using DMPO and Me2SO. Most of the peptides possessed superoxide dismutase- and catalase-like activities leading to the formation of either oxene [NiO]2+ or, in the case of beta Ala-His, hydroxyl radicals. Both these species may affect DNA integrity through distinct mechanisms.

Complexation of copper(II) by a peptide hybrid of bleomycin and amsacrine. Circular dichroism and electron spin resonance studies.

A model incorporating the metal chelating moiety of bleomycin and an anilinoacridine ring able to intercalate in DNA has been synthesized. The copper(II) complex of that molecule has been studied using circular dichroism and electron spin resonance by comparison with bleomycin. The introduction of the anilinoacridine ring involves a modification in the geometry of the complex. A distortion of the square-pyramidal form (type II complex) gives rise to a type I complex in which the metallic atom is drawn out of the plane of the four square-planar ligands and displaced slightly towards the fifth ligand.

Practice-based buprenorphine maintenance treatment (BMT): how do French healthcare providers manage the opiate-addicted patients?

UNLABELLED: France was the first country to promote the extensive use of buprenorphine for the treatment of drug-addicted subjects through the primary care system. To assess both professional commitment and patients' characteristics, all the physicians and pharmacists of a French area having prescribed/dispensed buprenorphine from 2/12/96 (the official release date) to 1/31/98 were identified from data files of the Health Insurance and then interviewed. During the first 61 weeks of buprenorphine maintenance treatment (BMT), 27.5% of physicians and 51.2% of pharmacists of that area were involved; 142 patient records were documented. Features of the clinical routines spontaneously implemented for practice-based BMT were: a high level of on-site supervised dispensation by the pharmacist (71% at treatment induction and 23% thereafter); the absence of objective measurement of illicit drug use; and a low buprenorphine dosage. These features are consistent with the lack of physicians' experience and training, and also the relatively good status of the population treated (no HIV-positives, heroin use duration averaging 4.2 +/- 3.1 years, and 81.7% with stable accommodations). Despite liberal regulations guiding BMT, a negligible proportion of cases had a "nomadic" attitude (multiple buprenorphine prescribers/deliverers). The treatment outcomes (no deaths, three drug overdoses, improvement in occupational status) are encouraging. CONCLUSION: Practice-based BMT appears to be a safe and acceptable response to moderate heroin addiction, but further training of the professionals involved and longitudinal investigations of individual outcomes are needed.

What are the reciprocal influences of randomized clinical trials and the patient-psychiatrist relationship?

The goal of this prospective investigation was to study the course and the quality of patient-psychiatrist relationships during phase II / phase III clinical trials of antidepressant medication prescribed for depressive disorders. All patients who participated in the clinical trials (and subsequently in this survey) signed written informed consent statements and were subject to random double blind treatment assignment. Retrospective analysis of 118 investigations was carried out, and the patients involved were questioned concerning their experiences and impressions during and after the study. Data show that the outcome of clinical trials of antidepressant drugs are not a function of pre-existing good patient-psychiatrist relationships. On the other hand, no effects on the patient-psychiatrist relationship were found as a result of the experimental procedure, and it can be concluded that no detrimental effects on future patient-psychiatrist relationships were incurred.

[Photophysical evaluation of photosensitization by various quinolones]. / Evaluation photophysique du pouvoir photosensibilisant de diverses quinolones.

An original physicochemical method is proposed for the evaluation of the photosensitizing activity of drugs in vitro. A Nuclear Magnetic Resonance (NMR) spectrum is recorded during light irradiation of drug solutions. The change in the intensity of the NMR lines under such conditions is termed the Photochemically Induced Dynamic Nuclear Polarization (Photo-CIDNP) effect. It is related to the formation of radical intermediates which may be involved in the in vivo photosensitization reactions (the so-called type-I photoreactions). Nine commercial quinolones were tested by this method: nalidixic, oxolinic, pipemidic and piromidic acids, rosoxacin, flumequine, enoxacin, pefloxacin and norfloxacin. Each quinolone was irradiated in alcoholic solutions in its UV absorption band (300-350 nm) in the absence or in the presence of a biological target chosen as a model: the amino-acid N-acetyltyrosine. The quinolones were classified in two groups in relation to the intensities of the observed CIDNP effects. Nalidixic and oxolinic acids, rosoxacin and flumequine are among the most potent photosensitizers.

Neuroprotective effects vary across nonsteroidal antiinflammatory drugs in a mouse model of developing excitotoxic brain injury.

Glutamate excitotoxicity is among the main cellular mechanisms leading to perinatal insults in human newborns. We used intracerebral injection of the glutamatergic glutamate N-methyl-D-aspartate-receptor agonist ibotenate to produce excitotoxic lesions mimicking the acquired white matter lesions seen in human preterm infants. We evaluated whether nonsteroidal antiinflammatory drugs (NSAIDs) protected against glutamate excitotoxicity. Aspirin (0.01-100 microg/d), indomethacin (0.1-10 microg/d), paracetamol (10-100 microg/d), or NS-398 (12.5 microg/d) was given daily before ibotenate (P1 to P5) or after ibotenate (P5 to P9). Lesion size was measured on Cresyl Violet-stained brain sections collected on P10. None of the drugs tested alone or in combination increased lesion size. Pretreatment with low- or high-dose aspirin and post-treatment with paracetamol or NS-398 protected against white matter lesions, whereas cortical lesions were decreased by pretreatment with low- or high-dose aspirin or post-treatment with NS-398. The corticosteroid betamethasone (0.18 microg/d) was neuroprotective when given before or after ibotenate and this effect was reversed by concomitant aspirin therapy (10 microg/d). In conclusion, perinatal NSAID administration may have beneficial effects on brain injury if appropriately timed.