Role of glutathione in the detoxification of ferriprotoporphyrin IX in chloroquine resistant Plasmodium berghei.

The reduction in hemozoin content is a well known feature of chloroquine-resistant Plasmodium berghei. Using NK65-derived lines displaying increasing resistance levels, we observed an inverse relationship between the hemozoin content, and the glutathione (GSH) and glutathione S-transferase (GST) levels. Treatment of highly chloroquine-resistant-infected mice with buthionine sulfoximine (BSO), which has previously been shown to partially reverse this chloroquine resistance, led to a significant increase in hemozoin production. In vitro studies on the polymerization of ferriprotoporphirin IX (FPIX) at pH 5.0 showed that GSH partially inhibited beta-hematin synthesis, while GST had a trivial and non specific effect. Furthermore, chloroquine-sensitive parasites invading reticulocytes displayed higher GSH level and GST activity, and reduced hemozoin synthesis and susceptibility to chloroquine. We conclude that, in chloroquine resistant P.berghei, GSH can detoxify hemin within the food vacuole, thus precluding its polymerization and preventing the activity of chloroquine and other quinoline-containing drugs. It is proposed that vacuolar GSH could be ascribed to an erythrocytic origin, since the resistant lines invade reticulocytes, which contain higher levels of GSH and GST than normocytes.

Schistosoma mansoni: in vitro adhesion of parasite eggs to the vascular endothelium. Subsequent inhibition by a monoclonal antibody directed to a carbohydrate epitope.

Schistosoma mansoni eggs come into direct contact with the vascular endothelium, particularly in the postcapillary venules of the mesenteric tract (oviposition site). We investigated the adhesion of eggs to endothelial cells in a static in vitro assay and in a flow-based in vitro assay. Live S. mansoni eggs rapidly attached, in a time-dependent manner, to the human endothelial cell line ECV 304, but not KOH-treated eggs. Activation of ECV monolayers with interleukin-1 promoted live S. mansoni eggs adhesion. An in vitro flow-based assay of human umbilical vein endothelial cells (HUVEC) showed the influence of wall shear stresses on the attachment of eggs to endothelial cells, particularly under postcapillary venule shear stress conditions. Interleukin-1 activation of HUVEC promoted adhesion between live eggs and endothelial cells. Higher wall shear stresses were needed to obtain the detachment of eggs from activated endothelial cells than control cells. Preincubation of interleukin-1-activated HUVEC, in a static in vitro assay, with monoclonal antibodies specific for intercellular adhesion molecule-1, E-selectin, and vascular cell adhesion molecule-1 significantly decreased adhesion of live eggs. Previous studies have shown that a monoclonal antibody specific for a schistosome carbohydrate epitope abundant in eggs is related to the Lewis X antigen. In this study, the anti-Lewis X-specific monoclonal antibody was used for adhesion-inhibition assays. Preincubation of eggs with this monoclonal antibody significantly decreased adhesion of live eggs to interleukin-1-activated HUVEC cultured in vitro. These results suggest that surface adhesion molecules, expressed by endothelial cells under conditions of interleukin-1 activation, directly participate in egg adhesion and that egg carbohydrate antigens play an important role in live S. mansoni egg adhesion to the vascular endothelium.

High-level chloroquine resistance of Plasmodium berghei is associated with multiple drug resistance and loss of reversal by calcium antagonists.

The chloroquine resistance of Plasmodium falciparum is reversed in vitro by numerous compounds, including calcium antagonists, which could enhance the accumulation of the drug in the parasite food vacuole. However, this mechanism of resistance could be insufficient when the resistance level increases. Using in vitro drug trials on strains of Plasmodium berghei displaying various chloroquine-resistance levels, we confirmed previous results obtained in vivo in the chloroquine-resistant strains of P. berghei are cross-resistant to related drugs (amodiaquine, quinine and mefloquine), the resistance levels to these drugs being related to their analogy to chloroquine. Furthermore, we showed that high-level resistant lines were associated with a loss of drug potentiation by verapamil and nicardipine in vivo, but that the reversal rates obtained in vitro are of low significance. We conclude that the parasite is able to escape the activity of these reversing agents.

[Immunofluorescence reaction of antibodies directed against the intestinal epithelium of Schistosoma mansoni. VI. Immunolocalization of a carbohydrate epitope at different developmental stages]. / Etude par la réaction d'immunofluorescence des anticorps dirigés contre l'épithélium intestinal de Schistosoma mansoni. VI. Immunolocalisation d'un épitope glucidique aux différents stades évolutifs.

In the course of previous works, we described an IgM monoclonal antibody directed to a carbohydrate epitope located on the gut epithelium surface of the Schistosoma mansoni adult worm. We provided evidence that this epitope was present in all stages of the parasite and was particularly abundant in eggs. The current work was performed in order to specify the epitope localisation, at each stage, by immunohistochemical techniques. The epitope appears to be located on the peripheral membranes of the adult worm, while it is produced by the alive miracidium in the eggs located in the tissues and subsequently spread out inside the periovular granuloma. Moreover, in adult worms, the observed structure presents itself as a soluble form in organic solvents; on the other hand, in eggs, the epitope was essentially found made of an hydrosoluble substance. These datas can explain why, in experimentally infected mice, the epitope is mainly determined in urines at the sixth week of infestation, when eggs are settled down in the tissues. Besides, the inhibition of the monoclonal antibody fixation by a pentose which contains the Lewis X antigen, painted out that the carbohydrate structure recognised by the monoclonal antibody could be the Lewis X antigen or a very closed structure.

Endothelium activation related increase of soluble intercellular adhesion molecule-1 in human schistosomiasis. Lack of correlation with serology.

Soluble intercellular adhesion molecule-1 (sICAM-1) level was measured in sera from 41 patients with Schistosoma mansoni schistosomiasis and compared with the sICAM-1 level in 41 healthy subjects. A significant increase in serum sICAM-1 was observed in patients with schistosomiasis compared with control subjects. As they were inhabitants of the French Antilles, the patients were, however, not settled in a malaria endemic zone, allowing this cause of sICAM-1 enhancement to be eliminated. No correlation was found between the level of sICAM-1 and the schistosomiasis serological titre. Such results favour the hypothesis of an activation of vascular endothelial cells due to egg deposition.

[Epidemiology of certain endemic parasitic diseases in the town of Guadalupe (Republic of Sao Tome and Principe). II. Other endemic parasitic diseases]. / Epidémiologie de certaines endémies parasitaires dans la ville de Guadalupe (République de Saõ Tomé et Príncipe). II. Autres endémies parasitaires.

Stool, blood and urine specimens have been collected from 380 inhabitants of all age groups living in the small town of Guadalupe in May 1992. The seroprevalence of Falciparum malaria (96%), toxoplasmosis (73.3%), have been measured.

[Epidemiology of certain endemic parasitic diseases in the town of Guadalupe (Republic of Sao Tome and Principe) I. Schistosomiasis intercalatum and intestinal worms]. / Epidémiologie de certaines endémies parasitaires dans la ville de Guadalupe (République de Saõ Tomé et Príncipe). I. Schistosomose à S. intercalatum et verminoses intestinales.

Schistosomiasis intercalatum in known to exist in Saõ Tomé since 1988, (Corachan et al.). It is transmitted by Bulinus forskalii, (Brown et al., 1989). Stool, blood and urine specimens have been collected from 380 inhabitants of all age groups living in the small town of Guadalupe close to the Agua Traz river and Agua Polino. The prevalence of schistosomiasis by detection of S. intercalatum eggs in a 10 mg stool thick smear (Kato technique) is 25.5%. An excreted Schistosoma polysaccharide antigen, detected by means of a monoclonal antibody (Ripert et al., 1992), is found in 49.1% of the urine samples. Patients voiding S. intercalatum eggs in stools have been treated with praziquantel (40 mg/kg body weight), as recommended by WHO Expert Committee on Schistosomiasis, but it might be wise to also treat persons excreting antigen in urine. The prevalence of intestinal helminthiasis, ascariasis (73.7%), trichuriasis (73.7%) and necatoriasis have been measured.

Plasmodium berghei: implication of intracellular glutathione and its related enzyme in chloroquine resistance in vivo.

Glutathione (GSH) plays a critical role in the detoxication and the protection of cells against oxidative stress. In the present study we examined the relationship between the intracellular GSH levels as well as glutathione S-transferase (GST), glutathione reductase (GR), and glutathione peroxidase (GPx) activities and how they relate to Plasmodium berghei resistance to chloroquine. Resistant strains (CQR30 and CQR60) were selected in vivo from a sensitive strain (NK65). Marked increases in GSH levels and GST activity within resistant parasites were observed, compared to sensitive parasites. On the other hand, GR and GPx activities were similar in sensitive and resistant parasites. Treatment with chloroquine did not influence the intracellular level of GSH, but it was found to significantly decrease GR activity. Intracellular depletion of GSH, by a nontoxic concentration of buthionine sulfoximine (BSO), significantly sensitized the resistant parasites to chloroquine. These results suggest that the P. berghei resistance results from altered GSH and GST levels and activity, respectively, which enable the detoxification of chloroquine in resistant parasites.

[Study by the immunofluorescence reaction of antibodies directed against antigens of the gut epithelium of Schistosoma mansoni. V. Modulation of granulomatous reaction around the egg under the influence of an IgM monoclonal antibody]. / Etude par la réaction d'mmunofluorescence des anticorps dirigés contre les antigènes de l'épithélium intestinal de Schistosoma mansoni. V. Modulation de la réaction granulomateuse autour de l'oeuf sous l'influence d'un anticorps monoclonal de classe IgM.

The periovular granulomatous reaction has been reduced in vivo by an IgM monoclonal antibody. The granulomatous reaction has been obtained either in unsensitized, or sensitized as well as immunized mouse. The granulomatous reduction could be explained by a decrease in egg viability, owing to the fact that the monoclonal antibody is lethal against an in vitro miracidium suspension.

[Evaluation of an indirect hemagglutination test for the serodiagnosis of amebiasis]. / Evaluation d'un test d'hémagglutination indirecte amibiase (HAI) pour le serodiagnostic de l'amibiase.

167 sera have been tested to appreciate the value of an indirect hemagglutination test (Amibiase HAI FUMOUZE) comparatively to an agglutination test of sensibilized particles of latex (Bichro latex Amibe Fumouze BLA) Amibiase HAI test comes out as sensitive and specific for the detection of antibodies in patients suffering from visceral amoebiasis. But some antibodies are also detected in patients with an antecedent of amoebiasis, as it is usually the case with some other techniques. A high positivity of the indirect hemagglutination test, and the concordance between the test HAI and the BLA one are in favour of a visceral amoebiasis. While lower rates or discrepancy between the two tests may evoke an hidden infestation in patients coming out or originated from endemic zones.

Etude epidemiologique du foyer de bilharziose a schistosoma intercalatum de Bata (Guinee Equatoriale)

Un antigene polysaccharidique caracteristique du genre schistosoma excrete dans l'urine est mis en evidence; avant et apres traitement par le praziquantel (40 mg/kg) dans la ville de Bata; ou un foyer de bilharziose a schistosoma intercalatum a ete identifie. Le test de detection urinaire de l'antigene met en jeu un anticorps monoclonal et fait appel a la technique d'inhibition de l'hemagglutination passive. Parmi les 779 sujets examines 145; soit 18;6 pour cent d'entre eux eliminent des oeufs de schistosoma intercalatum dans leurs selles et 305; soit 39;1 pour cent excretent de l'antigene dans les urines; ce qui dans la bilharziose traduit l'existence d'une profonde impregnation antigenique de l'organisme

Enquete paludometrique dans trois villages de la vallee de la Kadei; Cameroun

L'enquete paludometrique menee en janvier 1991 dans trois villages riverains de la riviere Kadei a l'Est du Cameroun revele un paludisme hyperendemique. L'indice plasmodique des enfants de 2 a 9 ans est de 63;5 pour cent. La formule parasitaire montre la preponderance de plasmodium falciparum et la presence de plasmodium malariae et de plasmodium ovale. La reaction d'immunofluorescence met en evidence un indice serologique eleve et une acquisition precoce des anticorps antipalustres; reflets d'une transmission intense. La pression medicamenteuse est restee tres faible dans la population traditionnelle et la construction d'un barrage ne devrait pas modifier la morbidite palustre en raison d'une transmission deja tres intense dans la region

Etude epidemiologique des filarioses (onchocercose; loase; mansonellose); dans la vallee de la Kadei (Cameroun)

L'etude des filarioses est realisee dans trois villages proche du site prevu pour la construction d'un barrage sur la riviere Kadei (Cameroun oriental). La presence des microfilaires d'onchocerca volvulus est determinee par l'examen des biopsies cutanees. La prevalence parasitologique (37;9 pour cent) et les caracteristiques lesionnelles observees indiquent que l'onchocercose sevit dans la region au niveau de mesoendemie et se presente un facies de foret. Compte tenu de l'ecologie des vecteurs; cette etude d'impact montre que le barrage prevu ne devrait pas modifier d'une facon notable l'ecologie regionale et la transmission des filarioses dans la region

Etude epidemiologique des helminthiases intestinales (necatorose; ascaridiose; tricocephalose) dans la vallee de la Kadei (Cameroun)

Les examens coprologiques avec numerotation des oeufs dans les selles; pratiques dans les villages de Boden; Zimbi et colomines situes dans la vallee de la Kadei ou un barrage va etre construit; permettent d'evaluer les prevalences et les charges parasitaires de trois nematodoses intestinales; la necatorose; l'ascaridiose et la tricocephalose; tres repandues dans la region. Ces affections; et en particulier la necatorose; sont plus frequentes chez les femmes que chez les hommes et leurs prevalences sont plus elevees a Boden et a Zimbi en plaine que sur la colline de Colomines. Il est possible que la mise en eau de la retenue; en faisant remonter le niveau de la nappe phreatique; favorise la transmission par le sol de ces affections; notamment a Boden qui sera situe juste au bord du lac

Detection with a monoclonal antibody of a polysaccharide antigen, excreted in the urine, in the schistosomiasis intercalatum focus of Edea (Cameroon).

The detection in the urine specimens of a sample of the inhabitants of Edea of a polysaccharide antigen characteristic for the genus Schistosoma, with monoclonal antibody by means of the inhibition of a passive haemagglutination test, shows that this technique is very sensitive for measuring prevalence of schistosomiasis due to S. intercalatum. In Edea, looking for eggs in stool specimens gives a low prevalence rate of the disease because of the low parasitic load. The prevalence by age, according to the voiding of eggs, is evoluting parallel to the excretion of the antigen.

Effect of a mass treatment with praziquantel on the excretion in urine of a polysaccharide antigen used for diagnosis of schistosomiasis due to S. mansoni in Cameroon.

The detection in urine, with a monoclonal antibody, of an excreted polysaccharide antigen characteristic of the genus Schistosoma, allows evaluation of the effect of praziquantel used for mass treatment, in a focus of S. mansoni infection. Inhibition of the passive haemagglutination test, which was used for detecting the polysaccharide antigen in urine, is more sensitive for measuring prevalence than the determination of eggs in stools by means of direct examination and the formalin-ether concentration technique. Nine months after anthelminthic treatment, the percentage of inhabitants excreting antigen in urine diminished markedly, while the circulating antibody levels remained high. The test for detecting the antigen in urine seems to be the most efficient way to monitor the effect of mass treatment in intestinal schistosomiasis.

[Study of antibodies directed against antigens of the gut epithelium of Schistosoma mansoni using an immunofluorescence reaction. IV. Blocking action on immunity of an IgM monoclonal antibody]. / Etude par la réaction d'immunofluorescence des anticorps dirigés contre les antigènes de l'épithélium intestinal de Schistosoma mansoni. IV. Etude du pouvoir bloquant sur l'immunité d'un anticorps monoclonal de classe IgM.

The inhibitory effect on immunity is demonstrated by passive transfer experiments in mice. It can be shown in a secondary infection with Schistosoma mansoni and also in primary infection. The results indicate that blocking activity probably interfers with non specific immunity mechanisms.

Detection with a monoclonal antibody of an antigen, characteristic of the genus Schistosoma, excreted in the urine.

In the host, the antigen excreted by schistosomes in the circulating blood is concentrated in the urine. A mouse monoclonal antibody of the IgM class type lambda, directed against an epitope of the intestinal epithelium of the adult worm, is obtained. The antigen found in the urine of the host as well as the monoclonal antibody has been previously characterized. It is of a polysaccharidic nature, is thermostable and specific for the genus Schistosoma. The antigen is found at all stages of the life cycle and, particularly, in the egg where it is found in large amounts. Detection of the antigen is by means of inhibition of the passive haemagglutination test. There is a fundamental advantage in detecting the metabolic antigen excreted by schistosomes instead of looking for circulating antibodies. The antigen is directly released by the parasite itself, antibodies being, by contrast, produced by the host, indirectly therefore, and in a way that varies from one individual to the next. Collecting urine specimens is, for field workers, easier than obtaining blood from the inhabitants. The detection of the antigen in the urine is made a rather simple procedure since the antigen is concentrated by the kidney and free in urine, instead of remaining conjugated with antibodies like it is in the blood. When used in the Cameroon for the study of prevalence in two foci of schistosomiasis, intestinal (Nalassi Emana) and urinary (Barombi Kotto), the test detecting the antigen in urine gives good correlations with the parasitological examinations looking for eggs of S. mansoni and S. haematobium in feces and urine.

[Serodiagnosis of schistosomiasis mansoni using an egg extract semi-purified by precipitation with ammonium sulfate]. / Diagnostic sérologique de la bilharziose à S. mansoni à l'aide d'un extrait ovulaire semi-purifié par précipitation par le sulfate d'ammonium.

Fifty one sera from bilharziosis patients and thirty control sera were examined with a Schistosoma mansoni egg antigen purified by precipitation with ammonium sulphate at 50% saturation. Sensitivity and specificity were good and showed a good correlation with results obtained by MSA1 antigen, but antigen tested is far more easier to prepare than MSA1.