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B Pradines

Publications and source records attributed to B Pradines.

35 records · Page 2Linked to original sources
PubMed1999

In vitro activities of benflumetol against 158 Senegalese isolates of Plasmodium falciparum in comparison with those of standard antimalarial drugs.

The 50% inhibitory concentration (IC50s) of benflumetol (range, 12.5 to 240 nM; mean, 55.1 nM) for 158 Senegalese isolates were evaluated. Ten isolates (6%) showed decreased susceptibility to benflumetol. Benflumetol was slightly more potent against chloroquine-resistant isolates (P < 0.025). No correlation or weak correlations in the responses to benflumetol and pyrimethamine, chloroquine, amodiaquine, artemether, quinine, and pyronaridine were observed, and these correlations are insufficient to suggest cross-resistance. Benflumetol may be an important alternative drug for the treatment of chloroquine-resistant malaria.

Animals↗
PubMed1999

In vitro susceptibility of African isolates of Plasmodium falciparum from Gabon to pyronaridine.

The in vitro activity of pyronaridine was evaluated against 62 isolates of Plasmodium falciparum from Libreville, Gabon using an isotopic, drug susceptibility microtest and was compared with amodiaquine, chloroquine, quinine, and halofantrine activities. The mean 50% inhibitory concentration (IC50) values of the 62 isolates from Gabon to pyronaridine was 3.0 nM (95% confidence interval [CI] = 2.1-3.9). Pyronaridine was less potent against chloroquine-resistant isolates than chloroquine-susceptible isolates but more potent than chloroquine against chloroquine-resistant parasites. The cut-off value for in vitro reduced susceptibility to pyronaridine was an IC50 > 15 nM. Two isolates (3%) showed an IC50 > 15 nM. A significant positive correlation was found between the activities of pyronaridine and chloroquine (r2 = 0.26, P < 0.001), pyronaridine and quinine (r2 = 0.36, P < 0.001), pyronaridine and amodiaquine (r2 = 0.55, P < 0.001), and pyronaridine and halofantrine (r2 = 0.50, P < 0.001). This correlation suggests in vitro cross-resistance or at least in vitro cross-susceptibility, which is not necessarily predictive of cross-resistance in vivo. The present in vitro findings require comparison with those of clinical studies.

Adolescent↗
PubMed1999

[In vitro sensitivity of Plasmodium falciparum isolates from Gabon to chloroquine and cycloguanil].

The in vitro susceptibility of 91 Plasmodium falciparum isolates obtained from malaria-infected children living near Libreville (Gabon) was evaluated against chloroquine and cycloguanil (biologically active metabolite of proguanil), using an isotopic micro-drug susceptibility test. In vitro resistance to chloroquine and cycloguanil was observed in 83% (35/42) and in 38% (30/78) of the patients, respectively. Our data showed that 41% (16/39) of Gabonese field isolates were resistant both to chloroquine and cycloguanil. These findings are of great importance because they might indicate imminent chloroquine-proguanil failure, and there are not many affordable antimalarial drugs to replace chloroquine-proguanil combination.

Adolescent↗
PubMed1998

Synthesis and antimalarial activities of fluoroalkyl derivatives of dihydroartemisinin.

Fluoroalkyl ethers (4) of dihydroartemisinin (2) have been prepared by reaction of fluoroalkyl alcohols with dihydroartemisinin by different methods (BF3,Et2O or TMSCl catalysis or Mitsunobu reaction). Ethers 4a-d derived from primary fluoroalkyl alcohols were obtained in moderate to good yields by these methods. Ethers 4e-j have been prepared from fluoroalkyl secondary and tertiary alcohols and phenol using the Mitsunobu reaction. Although in vitro antimalarial activities of ethers toward Plasmodium falciparum W-2 asiatic strain are moderate, in vivo activities against Plasmodium berghei (NT 173) are excellent.

Animals↗
PubMed1998

[Considering disparities in resistance of Plasmodium falciparum in Africa in chemoprevention decisions].

OBJECTIVES: Assess the efficacy of preventive and curative treatments of imported malaria. METHODS: The in vitro drug susceptibility of mefloquine, chloroquine and cycloguanil was determined against African isolates of Plasmodium falciparum from imported malaria cases by an isotopic in vitro test or a genomic approach. RESULTS: Plasmodium falciparum resistance to mefloquine, chloroquine or to the dihydrofolate reductase inhibitor was present in 5.2%, 46% and 42% of isolates respectively. Plasmodium falciparum drug resistance to chloroquine or antifolinics was more frequent in permanent than in seasonal malarial transmission areas. Simultaneous resistance to chloroquine and antifolinics was observed in 17% of isolates between 1991 and 1994 and in 28% between 1995 and 1997.

Africa↗
PubMed1998

Plasmodium yoelii: identification of rhoptry proteins using monoclonal antibodies.

Thirteen monoclonal antibodies, obtained after immunization of mice with Plasmodium yoelii schizonts, were selected using immunofluorescence assay: they all presented typical fluorescence patterns of rhoptries. This antigen localization was confirmed by immunoelectron microscopy. The molecular weights of the recognized antigens are 68, 80, 105, 130 and 140 kDa as determined by immunoprecipitation and immunoblot under reducing and nonreducing conditions. These values are very similar to these of the low and high molecular weight complex components of Plasmodium falciparum. Furthermore, these antigens are soluble like P. falciparum rhoptry proteins. Interestingly, our monoclonal antibodies also reacted with two other Plasmodium species (Plasmodium berghei NKK173 strain and P. yoelii nigeriensis 798 VK strain), giving sometimes more complex labeling with apical, membranous, nuclear, or/and cytoplasmic localizations. Finally, none of the monoclonal antibodies stained the rhoptries of P. falciparum FCCE-1/Niger strain.

Animals↗
PubMed1998

In vitro susceptibility of Gabonese wild isolates of Plasmodium falciparum to artemether, and comparison with chloroquine, quinine, halofantrine and amodiaquine.

The in vitro activity of artemether against 63 African isolates of Plasmodium falciparum from Libreville, Gabon was evaluated using an isotopic drug susceptibility semi-microtest. The 50% inhibitory concentration (IC50) values for artemether were in a narrow range from 0.8 to 34.8 nM (mean IC50 5.0 nM) and the 95% confidence interval (CI95%) was 3.6-6.3 nM. In vitro decreased susceptibility or resistance were observed with artemether (14%), to chloroquine (90%), to quinine (32%). Isolate susceptibility to amodiaquine and halofantrine was high i.e. 100% and 98%, respectively. There was a significant positive correlation between responses to artemether and amodiaquine (r2 = 0.45, P < 0.001), artemether and chloroquine (r2 = 0.36, P < 0.001), artemether and quinine (r2 = 0.31, P < 0.001), and artemether and halofantrine (r2 = 0.19, P < 0.01). Positive correlation between these drugs suggests in vitro cross-resistance or at least common features in drug uptake and/or mode of action or resistance.

Adolescent↗
PubMed1998

In-vitro activity of pyronaridine and amodiaquine against African isolates (Senegal) of Plasmodium falciparum in comparison with standard antimalarial agents.

The in-vitro activities of pyronaridine, amodiaquine, chloroquine and quinine were evaluated against 161 isolates of Plasmodium falciparum from Senegal (Dielmo, Ndiop and Pikine), using an isotopic, micro, drug susceptibility test. The mean IC50 values (50% inhibitory concentration) for pyronaridine and amodiaquine were 3.8 nM (95% confidence interval (95% CI), 3.1-4.4) and 12.0 nM (95% CI, 10.0-14.0 nM), respectively. Pyronaridine and amodiaquine were more active than chloroquine against susceptible parasites. However, both drugs were significantly less active (P < 0.002 and P < 0.025) against chloroquine-resistant isolates than against chloroquine-susceptible isolates. Based on statistical calculation using the present data (mean IC50 + 2 S.D.), the cut-off value for in-vitro susceptibility to pyronaridine is IC50 < 15 nM; for eight isolates (5%) the IC50 was > 15 nM. No isolates tested showed resistance to amodiaquine (IC50 > 80 nM). Significant positive correlations, suggesting cross-resistance among these drugs in vitro, were found between pyronaridine and chloroquine (r2 = 0.19, P < 0.001), pyronaridine and quinine (r2 = 0.44, P < 0.001), pyronaridine and amodiaquine (r2 = 0.34, P < 0.001), amodiaquine and chloroquine (r2 = 0.14, P < 0.001), and amodiaquine and quinine (r2 = 0.21, P < 0.001). The present in-vitro findings require comparison with clinical studies.

Africa↗
PubMed1998

In vitro activity of artemether against African isolates (Senegal) of Plasmodium falciparum in comparison with standard antimalarial drugs.

The in vitro activity of artemether against 56 African isolates of Plasmodium falciparum from Senegal was evaluated using an isotope-based drug susceptibility semi-microtest. The 50% inhibitory concentration (IC50) values for artemether were in a narrow range from 0.8 to 15.2 nM (mean IC50 = 3.43 nM) and the 95% confidence interval (CI) was 2.50-4.36 nM. Artemether was equally effective on chloroquine-sensitive and chloroquine-resistant isolates (mean IC50 = 346 nM, 95% CI = 2.08-4.84 nM versus mean IC50 = 2.80 nM, 95% CI = 2.00-3.60 nM). There was a significant positive correlation between responses to artemether and mefloquine (r2 = 0.36, P < 0.001), artemether and quinine (r2 = 0.085, P < 0.05), artemether and halofantrine (r2 = 0.075, P < 0.05), quinine and mefloquine (r2 = 0.205, P < 0.01), quinine and halofantrine (r2 = 0.124, P < 0.05), and mefloquine and halofantrine (r2 = 0.801, P < 0.001). A positive correlation between these drugs suggests in vitro cross-resistance or at least in vitro cross-susceptibility.

Animals↗
PubMed1998

[Resistance to chloroquine and cycloguanil of Plasmodium falciparum in patients arriving in France after travel in Africa without chemoprophylaxis].

The in vitro susceptibility of chloroquine and the genomic profile of dihydrofolate reductase (DHFR) codon 108 was determined against african isolates of P. falciparum (Pf) from imported malaria cases without previous drug intake by an isotopic microtest or PCR + RFLP. Pf resistance to chloroquine or to the DHFR inhibitor was present in 49% and 46% of isolates, respectively. Pf drug resistance was more frequent in permanent than in seasonal malarial transmission areas and chloroquine plus DHFR resistance reached 28% in years 1995-97. Updating the guidelines for the prevention of malaria in travellers to Africa is necessary.

Africa↗
PubMed1997

Proguanil resistance in Plasmodium falciparum African isolates: assessment by mutation-specific polymerase chain reaction and in vitro susceptibility testing.

The antifolate proguanil is commonly used in the prophylaxis and treatment of Plasmodium falciparum malaria. A series of point mutations in the dihydrofolate reductase (DHFR) gene has been linked to differential susceptibility of varied P. falciparum clones or isolates to this drug. To survey the efficiency of proguanil prophylaxis in an African endemic region, and to evaluate the level of proguanil resistance in the corresponding parasite population, we performed drug susceptibility assays with P. falciparum isolates from Senegal, Kenya, and Niger. In parallel, we developed a mutation-specific polymerase chain reaction assay that enabled us to characterize mutations in the DHFR gene of the same isolates without in vitro parasite cultivation. We confirm previously available data showing that parasites harboring a point mutation from Ser108 to Asn present a decrease in susceptibility to cycloguanil (the active metabolite of proguanil), and we show that mutations in codons 51 and 59 appear to modulate the level of resistance to cycloguanil. No mutations in codons 16 and 164 were detected in resistant parasites, in contrast with results from some previous studies.

Africa↗
PubMed1996

In vitro activities of novel catecholate siderophores against Plasmodium falciparum.

The activities of novel iron chelators, alone and in combination with chloroquine, quinine, or artemether, were evaluated in vitro against susceptible and resistant clones of Plasmodium falciparum with a semimicroassay system. N4-nonyl,N1,N8-bis(2,3-dihydroxybenzoyl) spermidine hydrobromide (compound 7) demonstrated the highest level of activity: 170 nM against a chloroquine-susceptible clone and 1 microM against a chloroquine-resistant clone (50% inhibitory concentrations). Compounds 6, 8, and 10 showed antimalarial activity with 50% inhibitory concentrations of about 1 microM. Compound 7 had no effect on the activities of chloroquine, quinine, and artemether against either clone, and compound 8 did not enhance the schizontocidal action of either chloroquine or quinine against the chloroquine-resistant clone. The incubation of compound 7 with FeCI3 suppressed or decreased the in vitro antimalarial activity of compound 7, while no effect was observed with incubation of compound 7 with CuSO4 and ZnSO4. These results suggest that iron deprivation may be the main mechanism of action of compound 7 against the malarial parasites. Chelator compounds 7 and 8 primarily affected trophozoite stages, probably by influencing the activity of ribonucleotide reductase, and thus inhibiting DNA synthesis.

Animals↗
PubMed1996

[In vitro sensitivity of 85 Plasmodium falciparum isolates in the Fatick region, Senegal].

Increasing resistance of Plasmodium falciparum to chloroquine and other antimalarials has been reported in Africa. Only fragmentary data are available for Senegal. Although combined chloroquine-proguanil is soon scheduled for released on the market, few studies have been published concerning the susceptibility of isolates to either drug. The in vitro susceptibility of 85 Plasmodium falciparum isolates obtained between October 24 and December 2, 1995 from malaria-infected patients living in the Fatick Region of Senegal to five classical antimalarial drugs (chloroquine, cycloguanil, quinine, mefloquine, and halofantrine) was evaluated using an isotopic, semi-microtest. Twenty-nine percent of isolates were resistant to chloroquine (IC50 > 100 nM), 22% to cycloguanil (IC50 > 500 nM), 1% to quinine (IC50 > 500 nM), 22% to mefloquine (IC50 > 20 nM), and 8% to halofantrine (IC50 > 5 nM). Five percent of isolates were resistant to both chloroquine and cycloguanil. Positive correlation was observed between quinine and halofantrine activity and between mefloquine and halofantrine activity. These findings suggest cross resistance or reduced susceptibility between these antimalarial agents which all exhibit a methanolic function.

Animals↗
PubMed1989

[Lumbar epidural catheterization: estimation of the length of the inserted catheter].

A catheter in the epidural space can be the cause of various iatrogenic complications. In order to avoid leaving too great a length in the lumbar epidural space during epidural anaesthesia, graduated Tuohy needles can be used (Perifix), together with graduated epidural catheters. On the latter, a special marking shows that, when it reaches the needle hub, the catheter tip is at the needle bevel. Approximately 5 to 7 cm of catheter length are introduced into the epidural space. The needle is removed and placed upside down next to the catheter, with the hub in contact with the patient's skin. In this position, the distance between the special marking on the catheter and the graduation on the needle which marked the skin level is equivalent to the length of catheter in the epidural space. This distance, and therefore catheter length, can then be reduced to about 4 cm by carefully withdrawing the catheter. Some possible improvements of catheters and needles are discussed. Knowing exactly how much catheter is within the epidural space could be of particular importance whenever that space is uncommonly far from the patient's skin: obesity, oedema, use of the paramedian route or a very oblique angle of the needle in the sagittal plane.

Anesthesia, Epidural↗
PubMed1989

[Peranaesthetic iterative allergic accident; apropos of a case involving oxytocin].

Observation of an allergic peranaesthetic accident which occurred twice in the same patient for two successive cesarean sections. Because we could not avoid the renewal of this dangerous situation, we try to criticize our own attitude. This case is compared with others which have been published previously to attempt a strategy in order to prevent this woman from a third hypersensitivity reaction.

Adult↗