Ex vivo and in vitro impairment of CD36 expression and tumor necrosis factor-alpha production in human monocytes in response to Plasmodium falciparum-parasitized erythrocytes.

Severe malaria is associated with the failure of host defenses to control parasite replication, with the excessive secretion of proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha), and with the sequestration of parasitized erythrocytes (PEs) in the microcirculation of vital organs. The scavenger receptor CD36, known as a major sequestration receptor, has also been identified as an important factor in mediating nonopsonic phagocytosis of PEs by monocytes and macrophages. The specific consequence of this phagocytosis is a decrease in parasite-induced TNF-alpha secretion. We evaluated the variations in CD36 level and in lipopolysaccharide (LPS)-induced TNF-alpha production in monocytes from Plasmodium falciparum-infected patients and in vitro in the presence of PEs. Both the monocytes from infected patients and from in vitro culture showed a decrease of CD36 expression and a reduced production of TNF-alpha induced by LPS. Using incubation assays with no contact between monocytes and PEs, or in the presence of a soluble supernatant obtained from the incubation of monocytes and PEs, this study shows that decreased CD36 expression was posttranscriptional and not directly related to PEs phagocytosis. In addition, these culture models suggest that the reduced capacity of TNF-alpha production occurred in 2 phases. The early phase (24 hr) appeared to be CD36 dependent and the second phase (48 hr) was due to a soluble factor produced by PEs. These observations suggest that the control of the TNF-alpha production in malaria by monocytes was not entirely dependent on the phagocytosis of PEs by CD36 and that soluble factors produced by PEs could play a role in this process.

Toxoplasma gondii secretes a calcium-independent phospholipase A(2).

Phospholipases A(2) (PLA(2)) play an important role in Toxoplasma gondii host cell penetration. They are also key enzymes in the host cell response to the parasite invasion. PLA(2) hydrolyse cellular phospholipids, releasing multiple inflammatory lipidic mediators. We have investigated the biochemical characterisation of T. gondii PLA(2) activity in a mouse-cultured tachyzoite homogenate and in the peritoneal exudate from infected mice, using the hydrolysis of a fluorescent phosphatidylglycerol labelled at the sn-2 position. Spectrofluorimetry and thin-layer chromatography showed a PLA(2) activity (about 0.5-2 nmol/min per mg), calcium-independent, secreted into infected mice peritoneal exudate, with a broad pH activity ranging between 6.5 and 9.5 and resistant to a great number of potential PLA(2) inhibitors except dithio-nitrobenzoic acid (1 mM). An associated phospholipase A(1) activity was also displayed. These results suggest that Toxoplasma gondii displays specific phospholipases different from host enzymes and probably involved at critical steps of infectious cycle.

IgA antibody response during acquired and congenital toxoplasmosis.

Toxoplasma gondii specific IgA and IgM antibodies were quantitated by an antibody capture agglutination assay in 260 patients with acquired toxoplasmosis and from 94 fetuses suspected of congenital toxoplasmosis and 30 infected children. In acquired toxoplasmosis, IgA antibodies to T gondii were found in 95% of the cases. In congenital toxoplasmosis IgA antibodies were more frequently detected (75%) in cord blood than IgM antibodies (61%). They persisted after birth, in some cases for up to 24 months. IgA antibodies were also detected in fetuses whose mothers had toxoplasmosis during their pregnancy. In infected fetuses IgM and IgA antibodies were detected in fetal blood as early as week 24 of pregnancy. Detection of IgA T gondii antibodies may be useful for the diagnosis of some recently acquired infection and for the diagnosis and follow up of the infection in the fetus and neonate.

Immunological analysis of the aqueous humour in candida endophthalmitis. I: Experimental study.

An immunological study of aqueous humour and serum was carried out in experimental ocular candidosis in rabbits. Anti-candida antibody titres, immunoglobulin G, and albumin levels were evaluated in the aqueous humour and in the serum. A local synthesis of anti-candida antibodies was detected in numerous rabbits at the height of clinical activity of the lesions.

Immunological analysis of the aqueous humour in candida endophthalmitis. II: Clinical study.

An anterior chamber paracentesis was carried out on six patients with candida endophthalmitis and on control subjects. We endeavoured to find out if there was local production of antibodies by evaluating the anti-candida antibody titres, the immunoglobulin G, and the albumin levels in the aqueous humour and in the serum. A significant difference in the level of specific antibodies between patients and controls was found. Local synthesis of anti-candida antibodies was discovered in five out of six patients with candida endophthalmitis. There would seem to be a correlation between the severity of uveitis and antibody titres.

The evolution of ocular toxoplasmosis in anti-interferon gamma treated mice.

PURPOSE: A clinico-histopathological cross correlation was made to study the mechanism of tissue damage in toxoplasmic retino-choroiditis during an experimental reactivation of chronic toxoplasmosis and to compare the influence of treatment by sulfadiazine on the retinal lesions. METHODS: Chronically infected Swiss-Webster mice were treated, six weeks after infection, with an avirulent strain of Toxoplasma gondii (Beverley strain) with polyclonal rabbit antibody directed against murine interferon gamma. RESULTS: Mice treated by anti-interferon gamma developed clinical lesions between day 5 and day 30 (lesions including single foci of retinochoroiditis, multifocal lesions or diffuse areas of retinal necrosis). These lesions did not arise from borders of pre-existing scars. The retina was photographed with an operating microscope fitted with a 90 diopter lens. Biological study showed a significant rise of parasitic loads in the eye and brain. Histological examination is in favour of free organism dissemination via retinal vessels; the lesions are restricted to the inner retina and ciliary body, the parasites migrated from extra-ocular cysts via the vasculature. No cysts were seen at the beginning of the study; they were found at the scar phase and appeared in mice treated with sulfadiazine. The clinical lesions were not caused by cysts but by coagulated necrosis in the retinal tissue. Parasite migration may have played a trigger role. CONCLUSIONS: The retinal damage was constituted either as a result of a toxic effect of the organisms or as a hypertensive reaction to the toxoplasma organism. The results of this study showed that the treatment with anti interferon gamma was sufficient to reactivate chronic infection.

Neonatal screening for congenital toxoplasmosis in a cohort of 165 women infected during pregnancy and influence of in utero treatment on the results of neonatal tests.

The aim of this study was to determine the performances of methods used for the neonatal diagnosis of congenital toxoplasmosis. We included 165 pregnant women infected during pregnancy over a 10-year period. Fifty-seven cases of congenital toxoplasmosis were demonstrated (34.5%). Neonatal diagnosis gave positive results in 50 cases (88%). Parasites were isolated from placenta or cord blood in 61% of the infected newborns, more frequently from placenta (60%) than from cord blood (43%). This method was the only criterion of infection in 18% of these infected infants. The detection of specific IgM and IgA antibodies performed on 42 sera of infected infants allowed the diagnosis of congenital infection in 34 cases (81%). IgA antibodies were more frequently detected (60%) than specific IgM (50%). Neonatal and prenatal screening were carried out for 143 pregnant women. This combination diagnosed 39 of 40 infected infants (98%). Prenatal diagnosis identified 30 of 40 cases (75%). Nine cases were diagnosed through neonatal screening and one case with the postnatal follow-up. When prenatal diagnosis was positive, pyrimethamine and sulfadoxine were administered to the mothers (25 cases) in addition to spiramycin. Toxoplasma gondii was less frequently isolated in the placenta and the cord blood of these women (32% and 19%, respectively) than in women treated by spiramycin alone (83% and 63%) proving the antiparasitic action of these drugs. In conclusion, neonatal screening combining parasite detection in placenta and immunological methods on cord blood is essential particularly when prenatal diagnosis is negative. Therefore, when this diagnosis is positive, a treatment with pyrimethamine and sulfamide can be started in the first month of life.

A method to obtain large quantities of Toxoplasma gondii tachyzoites with extreme purity.

In order to extract genetic material from the intracellular parasite Toxoplasma gondii, large numbers of organisms free of host cells are necessary. A method is described in which the RH strain of T. gondii was cultivated in nonadherent U937 cells. The purification was done by countercurrent elutriation. The resulting population of 10(10) T. gondii contained only 0.17% host cell material. The method is simple, rapid, and minimizes the use of animals.

Prevalence of drugs of abuse in urine of drivers involved in road accidents in France: a collaborative study.

The collaborative, anonymous, case-control study was intended to determine the prevalence of opiates, cocaine metabolites, cannabinoids and amphetamines in the urine of drivers injured in road accidents and to compare these values with those of non-accident subjects ("patients") in France. Recruitment was performed nationwide in the emergency departments of five hospitals and comprised 296 "drivers" aged 18 to 35 and 278 non-traumatic "patients" in the same age range. Females represented 28.4% of "drivers" and 44.2% of "patients." Screening for drugs in urine was performed by fluorescence polarization immunoassays in each center. Each positive result was verified using gas chromatography-mass spectrometry (GC-MS), in a single laboratory. Statistical analysis comprised single-step logistic regression and simultaneously took account of confounding factors and the final differences in prevalence values between the two populations or different subgroups. Cannabinoids were found in 13.9% of drivers (16.0% of males and 8.3% of females, p < 0.05) and 7.5% of patients (12.3% of males, 1.6% of females, p < 0.0001); only in females was this prevalence higher in injured drivers than in patients (p < 0.05). Opiates were present in 10.5% of drivers' and 10.4% of patients' urine samples (NS), and were more frequent in urine samples positive for cannabinoids, in drivers (p < 0.01) as well as in patients (p < 0.001). The prevalence of cocaine metabolites in drivers and patients was 1.0 and 1.1% and that of amphetamines 1.4 and 2.5%, respectively. No causal relationship between drugs and accidents should be inferred from this retrospective study. Nevertheless, the high prevalence of cannabis and opiate (licit or illicit) use in young people, whether injured drivers or patients, has potential implications for road traffic safety in France. Cocaine and amphetamines did not appear to be a major problem, unlike the experience in other countries.

[Efficacy and tolerance of praziquantel (Biltricide) in the treatment of distomatosis caused by Fasciola hepatica]. / Efficacité et tolérance du praziquantel (Biltricide) dans le traitement de la distomatose à Fasciola hepatica.

OBJECTIVES: Due to the side-effects of dehydroemetine, we have chosen praziquantel, a broad-spectrum antihelmintic, as a treatment for distomatosis secondary to Fasciola hepatica in humans. The aim of this retrospective study was to evaluate the efficacy and tolerance to praziquantel in patients with this disease. METHODS: Twenty-five patients (12 men) with a definite diagnosis of distomatosis and no previous treatment were followed-up between 8 months and 3 years (> 18 months in 76% of cases). The follow-up was based on clinical, biochemical and serological criteria. All patients received praziquantel (75 mg/kg/day orally) for 5 days. Treatment was started after endoscopic or surgical removal of parasites locolized in the biliary tract, in two patients. A similar therapeutic course was administered twice in four patients with persistent clinical symptoms, hypereosinophilia or arch 2 on immunoelectrophoresis. RESULTS: Cumulative rates of patients with normalized eosinophilia and seronegativation at 6, 9 and 12 months were 55, 65, 75% and 55, 70, 100%, respectively. Complete recovery occurred in 18 patients (72%) whereas hypereosinophilia persisted for more than one year in 5 patients. No side-effects, except transient nausea in a few cases, were observed. CONCLUSION: Since praziquantel seems to be both effective and well tolerated in a large proportion of patients, this drug can be recommended as a first choice for distomatosis due to Fasciola hepatica in human.

[Anatomopathologic diagnosis of parasitosis in Congo]. / Le diagnostic anatomopathologique des parasitoses au Congo.

In the part ten years, 9,650 anatomopathologic examinations have been carried out in the National Laboratory of Histopathology for Public Health in Brazzaville: 250 cases of parasitic infestation were diagnosed. In order of frequency were noted; 144 cases of bilharzia due to Schistosoma haematobium with 75 genito-urinary localisations and 51 appendicular cases, 31 cases of onchocercosis with a majority of subcutaneous nodules (17), 17 cases of digestive helminthiasis all locate in the ileo-caecal-appendix and discovered during systematic appendicular exploration, 13 cases of colitic or recto-sigmoidal amebiasis. These results point out 68 cases of appendicular parasitism. This should be in favour of more systematic anatomopathological examination of the ileo-caecal appendix both in tropical and in temperate regions.

[Latex agglutination reaction for the diagnosis of toxoplasmosis]. / Etude d'une réaction d'agglutination au latex pour le diagnostic de la toxoplasmose.

Agglutination of latex-particles sensitized with toxoplasma-antigen is a simple, fast, inexpensive test for toxoplasmosis-diagnosis. This test has been compared with passive-hemagglutination (1091 sera) and immunofluorescence (1093 sera). From the results, this new test is showed to be closer to passive-hemagglutination than indirect immunofluorescence. After studying possible false results and biological qualities it is thought that this test has good qualities to render great services for the toxoplasmosis diagnosis, and specially for epidemiological investigations.

[Epidemiology of toxoplasmosis in mothers and children in tropical Africa]. / Epidémiologie de la toxoplasmose chez la mère et l'enfant en Afrique tropicale.

The purpose of this study was the epidemiology of toxoplasmosis in Congo, Ivory Coast (IC), Niger, Centrafrican Republic, Zaïre. This statistical study was relied upon the search of IgG and IgM antibodies. In Niger, the risk connected with the first contact of the parasite was very low for children and young women, since only 2.6% of children under 15 years were carrying IgG and 5.4% of women between 15 and 30. In the other countries, the highest risk of first contact occurred before reaching 10 years and mostly between 5 and 9 (the IgG survey was confirmed by IgM survey). Nevertheless, IgM survey had indicated that for the young women there was a risk of first contact until reaching 20 years in IC and 30 years in Congo. A comparative study of antibodies developed among the couple mother-children was conducted in IC and Congo.

[Comparison of protein concentrations in saliva and serum]. / Comparaison des concentrations protéiques de la salive et du sérum.

Saliva and serum protein profiles composed of 12 proteins: IgA, IgG, IgM, albumin, transferrin, alpha 1-glycoprotein acid, alpha 2-macroglobulin, alpha 1-proteinase inhibitor, haptoglobine, C3C, C4 and CRP were obtained by laser nephelometry of aliquots of samples of non-stimulated whole saliva and blood taken at the same time. The population of 138 controls of both sexes was divided into 4 age groups: 1 (20 to 29 years), 2 (30 to 39 years), 3 (40 to 49 years), 4 (50 to 60 years). Using the techniques developed for saliva assay, 10 proteins were measurable: IgA, IgG, IgM, albumin, transferrin, alpha 1-glycoprotein acid, alpha 2-macroglobulin, alpha 1-proteinase inhibitor, haptoglobulin and C3C. The C4 fraction and CRP were present at concentrations lower than the detection limit i.e. at 1.8 and 2.05 mg/l. In the serum 11 proteins were analysed, CRP occurring at less than 0.01 g/l. The statistical two-factor variance analysis test (sex and age) demonstrated the statistically significant influence of age in the saliva for alpha 1-PI and alpha 2-M in the serum for Tf, alpha 2-M and alpha 1-PI, and sex in the serum for IgG, IgM, alpha 1-PI, alpha 2-M and also the interaction of both factors in the serum for alpha 2-M.

[Toxoplasmosis in the Republic of Senegal. Sero-epidemiological survey]. / Toxoplasmose en république du Sénégal. Sondage séro-épidémiologique.

The presence of Toxoplasmosis in Senegal was investigated by the detection of IgG antibodies. 415 samples were obtained from healthy subjects from different regions of the country. In subjects of over 30, a greater number were found positive for IgG antibodies if they lived in a humid climate (25% in Northern Senegal, 57.7% in eastern Senegal). In Dakar 33.3% of the pregnant women studied had antibodies. This study confirms the presence of Toxoplasmosis in Senegal.

[Toxoplasmosis in the Central African Republic. Complementary study in a rural area]. / La toxoplasmose en République centrafricaine (RCA). Etude complémentaire en zone rurale.

The epidemiological survey on the incidence of toxoplasmosis in rural areas of Central African Republic was carried out on a healthy population. The 814 samples came from 5 regions with 4 different climates. About 40% of the adults had IgG antibodies against Toxoplasma gondii except in pre-desert area where only 25% were positive. Girls became positive earlier than boys, but there was no difference between adult men and women except in pre-desert zone where men were more positive.

[Toxoplasmosis in the Congo Republic. Seroepidemiological study]. / La toxoplasmose en République du Congo. Etude séroépidémiologique.

Our study group, which was composed of over 2,500 subjects, aged between 0 and 65 years, came from different regions of Congo. The samples obtained were examined for the presence of IgG and IgM against Toxoplasma gondii. IgG were detected in about 33% of children over 9 years and in about 40% of adults. A study of IgM confirmed the early contact of children with the parasite (11% of positive samples for children between 4 and 9) and that of young women (5 to 7% positivity for subjects between 15 and 30). In spite of local variations, the extremely humid climate did not allow us to detect a difference based on the origin of the samples as furthermore there seems to be an ethnic factor involved. Among the different types of professions in our sample only farmers appear to be less frequently positive. Diet, as well as contact with animals do not seem to have an influence.

[Local production of specific antibodies in the aqueous humor in experimental Candida endophthalmia in rabbits]. / Etude de la production locale d'anticorps spécifiques dans l'humeur aqueuse dans l'endophtalmie expérimentale à Candida du lapin.

An increasing frequency of ocular lesions due to Candida albicans has been reported, but clinical detection of lesions, which may cause permanent blindness, remains difficult. Hematogenous endophthalmitis caused by Candida albicans in the rabbit is a useful model to study the pathogenesis of the disease, and perhaps to find new methods of biological diagnosis. A suspension of Candida albicans was injected in 15 rabbits, according to the method described by Edwards et al. In 1975, causing uni or bilateral chorioretinitis in 12 of them. Unaffected eyes were chosen as controls. After aspiration of the anterior chamber fluid, serum and aqueous humour titres of specific antibodies were determined. A local synthesis of IgG antibodies was detected, after comparison of the titres of specific antibodies in the aqueous humour and in the serum, related to the serum and aqueous humour concentrations of IgG antibodies. According to a formula proposed by Witmer and Desmonts in ocular lesions due to different pathological agents, we calculated the "C" coefficient: C = antibody titres aqueous humor/serum x IgG serum/aqueous humor. A local synthesis of specific antibodies in cases of experimental endophthalmitis leads us to believe that aqueous humour aspiration could be used in the diagnosis of endophthalmitis in humans.