Early detection of cellular immunity in congenitally Toxoplasma gondii-infected children.
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Animals↗
Biomedical subjects
F Peyron
Publications and source records attributed to F Peyron.
Flow cytometric quantification of Toxoplasma gondii cellular infection and replication.
The invasion and replication of Toxoplasma gondii are usually analyzed through either optical microscopy or incorporation of tritiated uracil. A new method has been developed using flow cytometric analysis to examine the entry and replication of T. gondii RH strain in Saimiri brain endothelial cells. After cell fixation and permeabilization using saponin, intracellular T. gondii were labeled with a monoclonal antibody against T. gondii SAG-1 (P30; the major cell-surface antigen) followed by fluorescein-conjugated rabbit anti-mouse IgG. The percentage of infected cells obtained using flow cytometry correlated directly with that obtained by UV light microscopy (r = 0.97). The mean fluorescence intensity of infected cells reflects intracellular P30 and assesses intracellular replication. The distribution of fluorescence per infected cell, considered with the percentage of infected cells, also allows a qualitative analysis of replication. Such a method is rapid, easy, and does not require specialized equipment for radioactive labeling.
Animals↗
[2020, the odyssey of tropical medicine: the emergence of non-transmissible diseases].
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Age Distribution↗
Advanced laboratory techniques for diagnosing Toxoplasma gondii encephalitis in AIDS patients: significance of intrathecal production and comparison with PCR and ECL-western blotting.
The polymerase chain reaction (PCR) for detection of cerebral spinal fluid (CSF) Toxoplasma gondii DNA was combined with the study of intrathecal antibody synthesis by antibody specific index calculation (ASI) and the detection of specific oligoclonal IgG bands (OCB) by affinity mediated immunoblotting (AMI) in 11 AIDS patients with T. gondii encephalitis (TE) and in 20 control patients with or without neurological disorders. Enhanced chemiluminescence (ECL) western-blot technique was employed to evaluate the antigenic specificity of CSF-IgG towards individual T. gondii antigens. PCR was positive in all TE patients which displayed brain-derived or blood-derived specific OCB, even when comparative ASI failed. Four TE patients had a unique anti-T. gondii OCB restricted to the CSF and a strong antibody response toward the 29 kDa band by ECL western blot. This response could be an important marker to discriminate TE from other opportunistic central nervous system (CNS) infections in the course of AIDS.
Acquired Immunodeficiency Syndrome↗
Circulating Toxoplasma gondii-specific antibody-secreting cells in patients with congenital toxoplasmosis.
Patients with congenital toxoplasmosis occasionally show rises in serum antibodies to Toxoplasma gondii (serological rebound), but the underlying cause remains unclear. The acute or chronic presence of available antigen often causes the appearance, in the peripheral blood, of cells actively secreting specific antibody. We have evaluated the capacity of circulating blood cells from 91 children born to T. gondii-infected mothers to actively synthesize anti-T. gondii antibodies according to their serological status. Supernatants from 7-day cultures of peripheral blood mononuclear cells were evaluated for antibody by cytofluorimetry. Only 1 of 49 subjects with low and stable serum antibody titers produced specific antibodies on cultures, while 9 of 22 subjects with recent rebound were positive. One of the positive children alone showed clinical signs of parasite activity. These observations suggest that rebound may be associated with production of available parasite antigens, possibly associated with reactivation. Differentiation from other causes, such as polyclonal B cell stimulation, would improve our ability to detect clinically significant reactivation and to prevent complications.
Adolescent↗
Estimation of the avidity of immunoglobulin G for routine diagnosis of chronic Toxoplasma gondii infection in pregnant women.
Present serological methods differentiate poorly between acute and chronic toxoplasmosis in pregnant women, particularly when immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies to Toxoplasma gondii are present simultaneously. In the present study, a simple test for discriminating between high-avidity antibodies, which are usually present in chronic infections, and low-avidity antibodies, typical of acute infection, was evaluated. Sera were evaluated for Toxoplasma gondii antibodies using a commercial enzyme immunoassay, but a duplicate well was washed in 6M urea to disrupt low-avidity complexes. Results are expressed as the percentage of antibodies resisting elution by urea. Equivocal sera (n = 493) containing both IgG and IgM Toxoplasma gondii antibodies from 309 pregnant women whose status as chronically or acutely infected had been independently determined using standard methods were evaluated for antibody avidity. A value of > 35% elution-resistant antibodies was always associated with chronic infection and could absolutely exclude a recent (< 3 months) infectious incident. Values of < 35% require repeat testing four weeks later to confirm the patient's status, since a proportion of individuals with chronic toxoplasmosis maintain low-avidity antibodies over long periods. This inexpensive, simple method can provide reassurance to clearly chronically infected individuals and avoids the need for repeated testing in these cases.
Acute Disease↗
Human platelet inhibition of Toxoplasma gondii growth.
The human platelet contribution against the intracellular growth of the parasite in vitro in human pulmonary fibroblasts was explored. It was observed that tachyzoites of Toxoplasma gondii induced activation of human platelets and additionally that platelets mediated inhibition of intracellular growth in a virulent T. gondii strain. A prominent role for platelet-derived growth factor (PDGF) was demonstrated in this phenomenon, by testing human recombinant PDGF-AA, -AB and -BB and antibodies to human PDGF-AB that partially reversed its effects. Moreover, the effect of PDGF was significantly higher if the host cells were treated 2 h before parasite infection. PDGF was not directly 'toxic' to free tachyzoites, but only affected parasites within host cells. PDGF-mediated inhibition may involve the cyclooxygenase cycle of the fibroblasts being partially reversed by the cyclooxygenase inhibitors, acetylsalicylic acid and indomethacin. However, a thromboxane synthetase pathway was not implicated. PDGF action against intracellular tachyzoites may also include increased IL-6 production in fibroblasts. Finally, transforming growth factor-beta 1 (TGF-beta1), another component of alpha-granules released at the same time as PDGF, may not be antagonistic to the PDGF parasite inhibitory effect in confluent host cells.
Animals↗
Phenylalanine derivatives active against Toxoplasma gondii brain cysts in mice.
The action of phenylalanine derivatives against a cyst forming strain of Toxoplasma gondii was tested in vitro and in vivo in mice. These compounds were Phe-Phe-OMe (dipeptide methyl ester) 1 and its cyclized product, 3,6-dibenzyl-2,5-dioxopiperazine 2, Boc-L-Phe 3, L-Phe-OMe 4, Boc-L-Phe-L-Phe-OMe 5. After a 48 hr incubation in vitro, the compounds 3 and 5 induced a higher inhibition than the control molecule, pyrimethamine. In the in vivo studies, the compound 3 induced a 77% decrease in the number of cerebral cysts, comparable to pyrimethamine. Compounds 1, 5 and 4 induced a decrease of about 63% in the cyst number. A size reduction and an alteration of the wall of treated cysts were often noted. In a histological study, a reduction in cyst size without either inflammation or intervention of the nevroglial cells was observed. The present study provides evidence on the efficacy of phenylalanine derivatives and especially Boc-Phe 3, against T.gondii brain cysts in mice.
Animals↗
Fluorogenic detection of viable Toxoplasma gondii.
In order to easily assess growth and destruction of Toxoplasma gondii in vitro, this report describes two double staining assays that both visualize live and dead organisms: acridine orange--ethidium bromide (AO-EB) and bisbenzimide (Hoechst 33258)--propidium iodide (B-PI). EB and PI were chosen for dead organisms staining while AO and B stain viable organisms. Thus, both double staining assays seem more informative than Giemsa staining or indirect immunofluorescence. They offer methods to study internal structure of the parasite as well as information on host-parasite relationships. Moreover, detection in culture are sensitive, easier, and less time consuming than previous methods. So, they should to be useful in strains behaviour analysis.
Acridine Orange↗
Value of cerebrospinal fluid cytochemical examination for the diagnosis of congenital toxoplasmosis at birth in France.
BACKGROUND: Because of routine screening and treatment of pregnant women for Toxoplasma infection in France, most neonates born to mothers who seroconverted during pregnancy are either not infected or asymptomatic. Early diagnosis relies mainly on radiologic, ophthalmologic and biologic tests. Cerebrospinal fluid (CSF) cytochemical evaluation is one of several tests performed in parallel to increase the overall sensitivity of the diagnostic evaluation. Our goal was to assess the value of cytochemical examination and to confirm whether using a portion of available CSF for this analysis is legitimate. METHODS: The individual performance of each of the two cytochemical tests and their combined value when used in parallel were assessed. These findings were then compared with the anti-Toxoplasma IgM and IgA serum titers and the clinical, ophthalmologic and radiologic findings at birth. RESULTS: CSF cytochemical analysis was possible in only 52% of the 233 children in the study. Our results in 112 children indicated poor sensitivity estimates. There was no significant change in the posttest probability of infection compared with the pretest estimation of risk in cases of a negative finding. After a mean follow-up of 80 months there was no evidence that CSF cytochemistry helped predict the risk of sequelae. CONCLUSION: In our setting cytochemical examination did not significantly contribute to the diagnosis of congenital infection at birth. Because of the limited quantity of CSF available, we suggest the use of other methods with higher yield.
Animals↗
A rapid flow cytometric method to explore cellular immunity against Toxoplasma gondii in humans.
To assess cell-mediated immunity to Toxoplasma gondii, we evaluated the expression of the activation antigens CD69, CD71, and CD25 on T lymphocytes by flow cytometry after specific in vitro stimulation of whole blood from 127 T. gondii-positive and 63 T. gondii-negative patients. T lymphocytes from many seropositive individuals did not express CD69 at 24 h after T. gondii antigen stimulation, but CD71 and CD25 were easily detectable on T cells from seropositive individuals 7 days after specific activation. CD25 was mainly expressed by stimulated CD4(+) T cells, and its detection on total T cells was both a sensitive (98%) and a specific (97%) indicator of prior T. gondii infection. These results make flow cytometric detection of CD25 an excellent candidate for screening cell-mediated immunity to T. gondii in vitro and an interesting tool for the diagnosis of congenital infection.
Adolescent↗
Identification of Encephalitozoon intestinalis in travelers with chronic diarrhea by specific PCR amplification.
With the use of Weber's modified trichrome and Uvitex 2B techniques, spores of microsporidia were detected in the stools of four travelers presenting clinically with chronic diarrhea. The general health of these patients was not impaired, and human immunodeficiency virus screening was negative. Immune evaluation, including the study of lymphocytic subpopulations, assay of serum immunoglobulins, and an intradermal multitest, showed normal results. Molecular identification of microsporidian species was based on the PCR amplification of a small-subunit rRNA sequence followed by HinfI endonuclease restriction. Encephalitozoon intestinalis microsporidiosis was thus shown in two of the four patients examined. In two patients, therapy based on albendazole made stools devoid of microsporidian spores without influence on the intestinal disorders. The pathogenic role of E. intestinalis in immunocompetent individuals remains to be demonstrated.
Animals↗
Alterations of Toxoplasma gondii induced by 2',3'-dideoxyinosine in vitro.
The time-course of action of the antiviral agent 2',3'-dideoxyinosine (ddI) against Toxoplasma gondii tachyzoites in vitro and its effects at the ultrastructural level were investigated. The very short latency of effect and high efficacy of ddI were evidenced by the fact that the drugs' effects on parasite growth occurred 2 hr after addition to the culture medium, and that an IL90 value of 0.5 microg/ml was reached after 72 hr. Although without apparent effect on uninfected cells, ddI clearly acted on the intracellular parasites, which tended to disappear. Remaining tachyzoites were almost exclusively extracellularly located and often exhibited a clustering of mitochondria-like bodies and subsequent deep alterations of their plasma membranes. These results confirm previous findings and emphasize the potential usefulness of ddI in the management of cerebral toxoplasmosis, a major health problem in acquired immune deficiency syndrome patients.
Animals↗
In situ expression of PLP/DM-20, MBP, and CNP during embryonic and postnatal development of the jimpy mutant and of transgenic mice overexpressing PLP.
We analyzed by in situ hybridization the spatiotemporal expression of dm-20, myelin basic protein (MBP) and 2'-3' cyclic nucleotide phosphodiesterase (CNP) during embryonic and postnatal development of the normal mouse and two plp/dm-20 mutants: the jimpy mouse and a transgenic mouse overexpressing the plp gene. In the central nervous system (CNS) of the normal mouse, dm-20 mRNA was detected at embryonic day (E)9.5 in the laterobasal plate of the diencephalon. The pattern of expression of CNP transcript was superimposable on that of dm-20, but appeared slightly later, at E12.5. MBP mRNA was detected even later (E14.5), and, in addition, only in the caudal (rhombencephalon and spinal cord) territories of expression of dm-20 and CNP. These observations support our previous proposals: (1) dm-20-expressing cells in the germinative neuroepithelium are precursors of oligodendrocytes, and (2) oligodendrocytes emerge from distinct pools of precursors along the neural tube (Timsit et al., 1995). In the jimpy mutant, despite the mutation in the plp gene, cells of the oligodendrocyte lineage developed normally. It is only at the time of myelin deposition that oligodendrocytes die. During embryonic development of the transgenic mutant overexpressing plp, there were no alterations in the spatiotemporal pattern or the level of expression of dm-20 in the CNS, in contrast to the higher levels of dm-20 observed in the peripheral nervous system (PNS).
2',3'-Cyclic-Nucleotide Phosphodiesterases↗
Simultaneous determination of pyrimethamine and sulphadoxine in human plasma by high-performance liquid chromatography after automated liquid-solid extraction.
A high-performance liquid chromatographic method with ultraviolet detection is described for the simultaneous measurement of pyrimethamine and sulphadoxine in human plasma. After an automated liquid-solid extraction on a C8 cartridge, the compounds are separated on a C18 column by isocratic elution; the mobile phase is methanol-acetonitrile-water (10:25:65, v/v/v) with triethylamine (1%) and adjusted to pH 5.6 with phosphoric acid. The eluent is monitored with an ultraviolet detector at 240 nm. The limit of quantification was 10 ng/ml for pyrimethamine and 22 microg/ml for sulphadoxine. No chromatographic interferences can be detected from endogenous compounds, other anti-malarial drugs or major drugs used for the treatment of children. Sulphadimethoxine is used as an internal standard. The method is accurate and precision is good with relative standard deviations lower than 6%. The chromatographic procedure takes 11 min. The method is comparatively rapid, simple, sensitive and can be used for therapeutic drug monitoring, clinical and pharmacokinetic studies.
Automation↗
PMP-22 expression in the central nervous system of the embryonic mouse defines potential transverse segments and longitudinal columns.
PMP-22, a major constituent of peripheral nervous system (PNS) myelin, is also present in the central nervous system (CNS), in motoneurons of the cranial nerve motor nuclei and spinal cord (Parmantier et al. [1995] Eur. J. Neurosci. 7:1080-1088). The expression of PMP-22 in the CNS during embryonic and early postnatal development was investigated and showed a biphasic spatio-temporal pattern. The expression of PMP-22 started at embryonic day (E)11.5, in restricted longitudinal and transverse domains, in the ventricular zone of the spinal cord, rhombencephalon, mesencephalon and prosencephalon. In the mid- and forebrain, the PMP-22 signal was detectable in a longitudinal domain that followed ventrally the basal/alar boundary but could no longer be detected dorsally at some distance from the roof plate. Along the caudo-rostral axis, the territory in which PMP-22 was detected spanned the mesencephalon and the prosencephalon, extending caudally from the limit between the isthmus and the mesencephalon, and rostrally to the boundary between prosomeres 4 and 5 (p4/p5). In agreement with the prosomeric model of forebrain organization proposed by Puelles and Rubenstein ([1993] TINS 16:472-479), differences in the level of PMP-22 expression in p2, p3, and p4 clearly defined the p2/p3 and p3/p4 neuromeric boundaries. By E17.5, PMP-22 was no longer detected in the ventricular zone, but at E18.5 it began to be expressed in motoneurons of cranial nerve motor nuclei and, after birth, following a rostro-caudal gradient, in the ventral spinal cord.
Animals↗
Evaluation of drug use and cost of hospital care for AIDS patients between 1990 and 1994.
This study was designed to evaluate drug use and drug costs of treatment of 1112 AIDS patients at the Infectious Diseases Unit at F. Houphouët Boigny Hospital in Marseilles, France, between January 1, 1990 and December 31, 1994. All drug expenditures directly or indirectly related to AIDS treatment were recorded for both inpatients and outpatients. There were 1952 hospital stays. For each stay baseline characteristics including age, sex risk factors, costs, and duration of hospitalization were noted. Patients were mainly young male drug addicts around thirty years of age. Reason for admission was also noted. The overall number of admissions per year has decreased since 1991 probably due to development of outpatient care. The number of stays per patient per year has decreased since 1993 because of the use of more appropriate therapeutic and prophylactic protocols. The number of drugs used was high increasing from 750 in 1990 to 868 in 1994. Cost of treatment doubled between 1990 and 1994 due to the introduction of many expensive new drugs. Closer analysis showed that the greatest increase in expenditure involved 'antibiotic/antiviral', 'psychiatry/neurology' and 'specialized therapy'. Although not frequently prescribed, costly drugs such as immunoglobulins, hematopoietic growth factors, and parenteral nutrition solutions accounted for a high proportion of total costs. Since AZT, ddI and ddC were used mainly for outpatient treatment, their cost was low in inpatients. Cytomegalovirus-related retinitis, tuberculosis, and multiple infections were cost-intensive complications. The increasing number of cytomegalovirus infections underlines the need for cost evaluation and surveillance of this complication. This study demonstrates that cost of treating AIDS patients is rising due to the use of more and costlier drugs. This finding underlines the need to evaluate and compare new therapeutic modalities in terms of cost effectiveness.
Acquired Immunodeficiency Syndrome↗
Is halofantrine still advisable in malaria attacks?
Halofantrine is an antimalarial drug which is widely prescribed for the treatment of infections with chloroquine-resistant strains of Plasmodium falciparum. Chemically, it is a phenanthrene methanol, belonging to the aryl-amino-alcohol family. It has recently been recognized that this drug may induce rare but serious, cardiotoxic effects, including lengthening of the QTc interval, 'torsade de pointes' and induction of late ventricular potentials. These events are thought to be related to a quinidine-like action of the drug. In addition, severe haemolytic accidents have been reported, mimicking blackwater fever and indicating an immunological process. As a result of these side-effects, new guidelines for prescription and more cautious use of halofantrine, particularly as a stand-by treatment for febrile access among travellers, are required.
Antimalarials↗