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Biomedical subjects

M Maillard

Publications and source records attributed to M Maillard.

At least 37 records · Page 2Linked to original sources
PubMed1997

Monitoring antiretroviral activity using ICDp24 and CD4 counts in HIV infection.

The fluctuations of HIV-1 p24 antigen concentration have been monitored in the follow-up of 118 subjects in different clinical stages and compared to their CD4 cell count; 104 patients received antiretroviral therapy. Persistent (65%) or sporadic (28%) antigenaemia has been detected in most patients in different clinical stages. The variations of the p24 Ag level are significantly correlated with the CD4 cell count and therapy administration (P = 0.0001). In patients with relatively conserved immune function (CDC II and III), antiretroviral therapy shows the best efficacy and can be efficiently monitored by p24 and CD4 surrogate markers. The data here suggest that although the informative value of p24 Ag is not representative of an AIDS-defining event, it can be used as a short-term and relatively inexpensive virological marker of antiviral activity in vivo, to support the routine management of patients.

Anti-HIV Agents↗
PubMed1997

Application of neural networks to the follow-up of AIDS patients.

The present work aims to obtain groups of patients with similar profiles of p24 antigen concentration and of CD4+ cell counts. These two markers were chosen because their evaluation represents a significant step in the clinical follow up of HIV-1 infected subjects. The classifications were obtained by a Kohonen neural net trained in three ways: with p24 antigen profiles only, with CD4+ cell count profiles only and with both sets of profiles. The results show that the clustering fashion of the two parameters closely resembles the clustering fashion of CD4+ only rather than the one of p24Ag, both with reference to cluster formation and with reference to distance among clusters.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Risks and benefits of aerosolized pentamidine and cotrimoxazole in primary prophylaxis of Pneumocystis carinii pneumonia in HIV-1-infected patients: a two-year Italian multicentric randomized controlled trial. The Italian PCP Study Group.

We randomized 220 HIV-1-infected subjects to receive aerosolized pentamidine (300 mg/4 weeks) or orally trimethoprim-sulfamethoxazole (320-1600 mg/day) for primary prophylaxis of Pneumocystis carinii pneumonia (PCP), and evaluated PCP and toxoplasmic encephalitis (TE) occurrence and survival. Patients developing toxicity switched to the other regimen. Analysis was on intention-to-treat. At 1 year of study, we observed in the pentamidine group a non-significant excess of PCP (4 vs. 1) and TE (7 vs. 3), and a significant increased death rate (15 vs. 2). After 2 years, no significant differences were observed: adjusted RR estimates for pentamidine vs. cotrimoxazole were 1.20 (95% CI, 0.33-4.37) for PCP (6 cases vs. 5), 1.23 (95% CI, 0.46-3.29) for TE (10 vs. 8) and 1.52 (95% CI, 0.83-2.79) for death (30 vs. 18). Crossovers were more frequent in the cotrimoxazole group (41 vs. 4, P < 0.001). Aerosolized pentamidine and cotrimoxazole were equally effective in preventing PCP, and no major differences were observed in TE occurrence and survival after 2 years follow-up.

AIDS-Related Opportunistic Infections↗
PubMed1995

Better efficacy of twice-monthly than monthly aerosolised pentamidine for secondary prophylaxis of Pneumocystis carinii pneumonia in patients with AIDS. An Italian multicentric randomised controlled trial. The Italian PCP Study Group.

The aim of this multicentric randomised controlled trial was to evaluate long-term efficacy and safety of once-monthly versus twice-monthly 300 mg aerosolized pentamidine (AP) as secondary prophylaxis of Pneumocystis carinii pneumonia (PCP). We randomised 205 patients with a previous confirmed episode of PCP (107 treated with 300 mg once-monthly AP, and 98 with 300 mg twice monthly AP); the median review period was 232 days. Kaplan-Meier method and Cox's hazard regression model were used for analysis. The main outcome assessments were PCP recurrence, survival and incidence of drug toxicity. The two groups were balanced for prognostic predictors. In the once-monthly AP group, 14 relapses of confirmed PCP were observed, while five occurred in the twice-monthly AP group; the crude relative risk (RR) was 2.69 (95% CI 1.002-7.236, P=0.0496) and the adjusted RR accounting for prognostic predictors was 2.62 (95% CI 0.92-7.5, P=0.071). Death occurred in 36 of 26 patients respectively (adjusted RR 1.32, 95% CI 0.8-2.18, P=0.28). Two patients interrupted the study because of intolerance to AP (one in each group), and severe coughing occurred in two patients (one in each group). At the end of the study, pulmonary function tests were not changed compared with baseline and were the same between the two groups. Our study suggests that 300 mg twice-monthly AP is more effective than 300 mg once-monthly AP as secondary prophylaxis of PCP.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Comparative studies on the affinities of ATP derivatives for P2x-purinoceptors in rat urinary bladder.

1. Radioligand binding assays have been used to determine the affinities of a series of ATP derivatives with modifications of the polyphosphate chain, adenine and ribose moieties of the ATP molecule for [H]-alpha,beta-methylene ATP ([3H]-alpha,beta-MeATP) binding sites in rat urinary bladder. 2. The replacement of the bridging oxygen in the triphosphate chain of ATP (pIC50 = 5.58) with a methylene or imido group markedly increased the affinity (691 fold in IC50 values for beta,gamma-imidoATP, 15 fold for beta,gamma-methylene ATP), and the replacement of an ionized oxygen on the gamma-phosphate with a sulphur (ATP gamma S) also led to increased affinity (5623 fold in IC50 values). 3. Modifications at N6, N1, and C-8 positions on the purine base usually reduced the affinity of ATP (a decrease of 2.8 fold in IC50 values for N6-methylATP and 8.9 fold for 8-bromo ATP), while the attachment of an alkylthio group to the C-2 position greatly increased the affinity for P2x-purinoceptors (from 3.5 to 98 fold increase in IC50 values). 4. Replacement of the 3'-hydroxyl group on the ribose with substituted amino or acylamino groups produced more potent P2x-purinoceptor agonists (an increase of 447 fold in IC50 values for 3'-deoxy-3'-benzylamino ATP and 28 fold for 3'-deoxy-3'-(4-hydroxyphenylpropionyl)amino ATP. 5. Diadenosine polyphosphates (Ap[n]A) were also shown to displace the [3H]-alpha,beta-MeATP binding. The rank order of potency was Ap6A > Ap5A > Ap4A >> Ap3A >> Ap2A. 6. Suramin, PPADS, and reactive blue 2 could competitively displace the binding of [3H]-alpha,beta-MeATP toP2X-purinoceptors, with pIC50 values of 6.26, 5.35, and 6.22, respectively.

Adenosine Triphosphate↗
PubMed1993

8-(3-Chlorostyryl)caffeine (CSC) is a selective A2-adenosine antagonist in vitro and in vivo.

An adenosine antagonist, 8-(3-chlorostyryl)caffeine (CSC), was shown previously to be 520-fold selective for A2a-adenosine receptors in radioligand binding assays in the rat brain. In reversing agonist effects on adenylate cyclase, CSC was 22-fold selective for A2a receptors in rat phenochromocytoma cells (Kb 60 nM) vs. A1 receptors in rat adipocytes (Kb 1.3 microM). Administered i.p. in NIH mice at a dose of 1 mg/kg, CSC shifted the curve for locomotor depression elicited by the A2a-selective agonist APEC to the right (ED50 value for APEC shifted from 20 micrograms/kg i.p. to 190 micrograms/kg). CSC had no effect on locomotor depression elicited by an ED50 dose of the A1-selective agonist CHA. CSC alone at a dose of 5 mg/kg stimulated locomotor activity by 22% over control values. Coadministration of CSC and the A1-selective antagonist CPX, both at non-stimulatory doses, increased activity by 37% (P < 0.001) over CSC alone, suggesting a behavioral synergism of A1- and A2-antagonist effects in the CNS.

Adenosine↗
PubMed1993

Structure-activity relationships of 8-styrylxanthines as A2-selective adenosine antagonists.

A series of substituted 8-styryl derivatives of 1,3,7-alkylxanthines was synthesized as potential A2-selective adenosine receptor antagonists, and the potency at rat brain A1- and A2-receptors was studied in radioligand binding experiments. At the xanthine 7-position, only small hydrophobic substituents were tolerated in receptor binding. 7-Methyl analogues were roughly 1 order of magnitude more selective for A2 versus A1 receptors than the corresponding 7-H analogues. 1,3-Dimethylxanthine derivatives tended to be more selective for A2-receptors than the corresponding 1,3-diallyl, diethyl, or dipropyl derivatives. Substitutions of the phenyl ring at the 3-(monosubstituted) and 3,5-(disubstituted) positions were favored. 1,3, 7-Trimethyl-8-(3-chlorostyryl)xanthine was a moderately potent (Ki vs [3H]CGS 21680 was 54 nM) and highly A2-selective (520-fold) adenosine antagonist. 1,3,7-Trimethyl-8-[(3-carboxy-1-oxopropyl)amino] styryl]xanthine was highly A2-selective (250-fold) and of enhanced water solubility (max 19 mM). 1,3-Dipropyl-7-methyl-8-(3,5-dimethoxystyryl) xanthine was a potent (Ki = 24 nM) and very A2-selective (110-fold) adenosine antagonist.

Adenosine↗
PubMed1993

Search for antifungal, molluscicidal and larvicidal compounds from African medicinal plants.

African medicinal plants provide a rich source of biologically-active natural products. By the use of simple bioassays in conjunction with an approach involving bioactivity guided fractionation, it is possible to isolate novel compounds with interesting properties. Several hundred plant extracts have been submitted to different screens, including bioautography on TLC plates with the fungi Cladosporium cucumerinum and Candida albicans. Among the other test systems are a bioassay for molluscicidal activity with the schistosomiasis-transmitting snail Biomphalaria glabrata and a benchtop assay for larvicidal activity with larvae of the mosquito Aedes aegypti, the vector of yellow fever. Using a variety of modern separation techniques, a number of compounds with activity in these bioassays have been isolated. These include prenylated xanthones, tetracyclic phenols and saponins. The role of saponins and saponin-containing plants in the control of schistosomiasis is outlined.

Animals↗
PubMed1991

Ion channels involved in the presynaptic hyperexcitability induced by herpes virus suis in rat superior cervical ganglion.

Rat superior cervical ganglia infected with herpes virus suis (pseudorabies virus) display a spontaneous bursting activity of still unknown origin. Previous intracellular recordings from the ganglionic neurons combined with pharmacological studies showed that the postganglionic action potentials are induced by acetylcholine release spontaneously from the preganglionic nerve. In this study we investigated whether the acetylcholine release is caused by mechanisms which are dependent on action potentials spontaneously generated on the preganglionic nerve or by mechanisms which occur without any changes in the excitability of presynaptic fibers. Simultaneous intra- and extracellular recordings from the ganglion cells and from the preganglionic nerve, respectively, were performed 32-38 h after the inoculation of herpes virus suis (strain Aujeszky) into the anterior chamber of one eye of the rat. Tetrodotoxin, well known to prevent the generation of action potentials by blocking the fast sodium channels, completely and reversibly abolished, whereas the potassium channel blockers 4-aminopyridine and apamin, enhanced the spontaneous, bursting activity at pre- and postsynaptic levels. The nicotinic receptor antagonist hexamethonium abolished the postsynaptic discharges and reduced the preganglionic activity by 50%. Pre- and postsynaptic electrical activities were suppressed in low calcium Krebs' solution, demonstrating that extracellular calcium is required not only for acetylcholine release but also for triggering the presynaptic action potentials. It is concluded that in the infected ganglia the spontaneous acetylcholine release is due to the generation of action potentials in the preganglionic nerve. Voltage-gated sodium and calcium channels contribute to the presynaptic electrogenesis, while the latter appears to be damped by the activation of voltage- and calcium-dependent potassium channels. Possible factors as well as mechanisms inducing such an increase in excitability are discussed.

4-Aminopyridine↗
PubMed1991

[Indications of lithium plasma levels in professional practice. Average of a 7-year follow-up].

With a mean follow-up duration of 7 years, the retrospective analysis of 57 charts of lithiotherapy shows that: Better results are observed when the lithium blood level reactus 0.87 mmoles/l. In that case, the best lithiotherapy indication is the major recurrent long cycles depression. We also propose as lithiotherapy indication in order of efficacy: 1--The maniac-depressive psychosis (P.M.D.) in its mixed form. 2--The schizo-affective troubles. The curative and preventive lithium efficacy is on favour of the diagnosis of recurrent endogenous psychiatric disease.

Adult↗
PubMed1989

Partially N-desulfated heparin as a non-anticoagulant heparin: some physico-chemical and biological properties.

A partially N-desulfated preparation of heparin (UFH) obtained by thermally inactivating heparinic acid for 24 hours at 50 degrees C (TIHA) was examined for its physico-chemical and biological properties in vitro and in vivo. TIHA has a molecular weight of 14,700 and 27% remaining N-sulfate groups (UFH = 17,500; 100% N-sulfate groups). TIHA has no anticoagulant activity measurable by conventional amidolytic or clotting tests. However, in a rabbit stasis-induced thrombosis model and using two different thrombogenic stimuli (Feiba and PCC(Konyne)/RVV), TIHA afforded a dose-dependent (1.0-2.5 mg/kg) protection sufficient to impair thrombosis (UFH: fully effective at 0.13 mg/kg). TIHA did not produce any bleeding at supramaximal antithrombotic dosage in a rat tail bleeding and a rabbit ear blood loss model and it did not augment ADP-induced aggregation of platelets. In contrast, a completely N-desulfated derivative of UFH (Inoue and Nagasawa, Carbohydr. Res. 46, 87-95, 1976) also lacking measurable in vitro activity was completely inactive in vivo. The results in this study suggest that TIHA may be considered as a non-anticoagulant heparin still retaining antithrombotic activity and also with lower haemorrhagic effect than UFH.

Adenosine Diphosphate↗
PubMed1989

Wheat germ agglutinin (WGA) reduces ADH-induced water flow and induces cell surface changes in epithelial cells of frog urinary bladder.

The functional and structural changes induced by apical wheat germ agglutinin (WGA) 100 micrograms/ml exposure on frog urinary bladder have been investigated and the possible correlations between these effects discussed. Bladders, apically exposed to WGA for 30 min to 3 hr exhibit a marked reduction of their response to antidiuretic hormone (ADH) challenge and of their hydrosmotic reactivity. Structural changes triggered by WGA treatment are: 1. apical invaginations of the plasma membrane, interpreted as endocytotic in nature, taking into account the results of carbohydrate cytochemical detection and horseradish peroxidase (HRP) exposure: 2. cytoskeleton disorganization and microvilli collapse. These phenomena do not interfere with cortical granule traffic and are independent of ADH challenge: they occur in ADH-stimulated bladders as well as in bladders at rest. These findings could be interpreted as follows: binding of the divalent lectin WGA to its coat specific receptors would induce changes in the apical membrane structure which in turn could provoke disorganization and disruption of apical cytoskeletal elements associated with plasma membrane. Reduction of bladder response to ADH challenge could result from a reduced recycling of aggrephores, as they are associated with cytoskeletal elements in the subapical cytoplasm. Collapse of microvilli and endocytotic events also could result from apical cytoskeleton disruption, as microvilli are sustained by bundles of actin filaments interconnected with apical cytoskeletal filaments and as plasma membrane is associated with apical cytoskeleton. However, these two last events evidently occur in ADH-challenged or non-challenged bladders.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1985

Neurohypophysial peptides depress cholinergic transmission in a mammalian sympathetic ganglion.

The actions of arginine-vasopressin (AVP) and oxytocin (OXT) were investigated in the rat superior cervical ganglion (SCG). At micromolar concentrations AVP decreased the amplitude of fast excitatory postsynaptic potentials (f-EPSPs) evoked by preganglionic stimulation and in many cells depolarized the postsynaptic membrane. Both effects were reversibly abolished by a potent vasopressor antagonist. The peptide decreased the frequency of spontaneous miniature EPSPs and the quantal content of the f-EPSPs without affecting the sensitivity of the ganglion cells to acetylcholine. OXT exerted the same effects as AVP but was less powerful. It was concluded that neurohypophysial peptides exert a dual pre- and post-synaptic action mediated by specific receptors.

Action Potentials↗