Evaluation of a possible role of tissue inhibitor of metalloproteinases 1 (TIMP-1) in the pathogenesis of hydatid disease.

Tissue inhibitor of metalloproteinases-1 (TIMP-1), in the serum levels of 27 patients was significantly higher and almost a double of that measured in healthy patients. Considerably higher TIMP-1 levels were recovered in patients with higher specific antibody titers and those with hepatic cysts in relation to low-titer patients and pulmonary cysts respectively, reflecting an immunologic dose-dependent and cell type-specific regulation of TIMP-1 production. Yet, these higher TIMP-1 levels stop short to be statistically significant in both groups. Patients with multi-sited hydatid cysts also show statistically insignificant higher TIMP-1 levels compared to single-sited cysts.

Assessment of the role of soluble intracellular adhesion molecule-1 (sICAM-1) in the pathogenesis and as a marker of disease severity in different stages of human schistosomiasis and toxoplasmosis.

The role of soluble intracellular adhesion molecule 1 (sICAM-1) in the pathogenesis and its relevance to disease severity was assessed in different stages of human infection with S. mansoni, S. haematobium and T. gondii. The levels of sICAM-1, obtained in the current study correlated with disease severity, degree of cell destruction and type of immune response. Highest sICAM-1 levels were observed in only two groups (hepatosplenic schistosomiasis and patients with mixed active S. haematobium and T. gondii infections), while in the other two groups (separate cases of active S. haematobium infection or latent T. gondii infection) showed no significant rise in sICAM-1 levels.

A novel chemotherapeutic combination for Trichomonas vaginalis targeting purine salvage pathways of the parasite.

A novel combination of chemotherapy (Dipyridamole/Allopurinol) targeting the possible purine salvage mechanisms of Trichomonas vaginalis was used in this study. The possible effect of these drugs either individually or in combination, on the multiplication of T. vaginalis in modified TYM axenic culture, was assessed on 24 hours intervals. The combination of both drugs at concentrations of 5 microM and 10 microM each showed a potent lethal effect on the parasite and an almost complete inhibition of parasite multiplication in culture. Each drug, individually, has a significant but partial inhibitory effect on parasite multiplication. Surprisingly, allopurinol, a competitive inhibitor of hypoxanthine, a nucleobase that is not salvaged by the parasite, showed a more potent inhibitory effect on parasite multiplication than dipyridamole, a specific inhibitor of the transport of adenosine, a favored nucleoside to T. vaginalis. However, the inhibitory effect of either drugs declines with time in contrast with that of the combination of both drugs which continues throughout all time points of the experiment. These results prove that a combination of dipyridamole and allopurinol could be useful, not only in the treatment of trichomoniasis, but also in other parasites that are unable of de novo purine synthesis.

Reciprocal heterologous protection between Trichinella spiralis and Toxoplasma gondii concurrently present in experimental murine models.

Mixed parasitic infections have been long seen as a double impact on the host. In this study a different view of polyparasitism is demonstrated. The influence of the immunological environments created by two biologically different parasites on the pathogenesis of each other was evaluated. Swiss albino mice were sequentially infected with the intracellular protozoan Toxoplasma gondii (acute and latent), which elicits a T-helper 1 (Th1)-polarized immune response and the helminth parasite Trichinella spiralis, whose infection is predominated by a Th2 response. The results show a significant heterologous protection from one parasite towards the other. There was a highly significant lower Trichinella muscle larvae burden in mixed infection group compared to single Trichinella infection, in spite of delayed intestinal adult worm expulsion in the mixed infection group. A highly significant lower burden of T. gondii brain cysts in mixed infection compared to single latent Toxoplasma infection was also demonstrated. Concerning the anti-Toxoplasma antibody response, there was a significant lower levels in the latent Toxo-Trich. group compared to the group of latent toxoplasmosis only. These significant lower antibody titers were reproducible by two different assays; dye test and direct agglutination test.

Application of neural networks to the real-time diagnosis of acute toxoplasmic infection in immunocompetent patients.

Neural networks constitute a relatively new, radically different approach to the interpretation and recognition of subtle diagnostic patterns in multivariate data. In this study the use of neural networks with a single serum sample for rapid real-time recognition of recent toxoplasmic infection was investigated. A neural-network model was implemented on the basis of data obtained by four serological methods--dye test, indirect fluorescence assay, indirect hemagglutination assay, and IgM immunosorbent agglutination assay--and was "trained" to extract features of acute infection by application to an analysis of 65 immunocompetent patients, 10 of whom were in fact acutely infected. The trained model correctly classified all 10 cases of acute infection. On its application to 61 additional infected patients, this method correctly identified seven cases as potentially acute. Our study shows that neural networks can discern diagnostic patterns from variables that individually have limited utility in the diagnosis of acute toxoplasmosis.

Tandemly repeated genes encode nucleoside triphosphate hydrolase isoforms secreted into the parasitophorous vacuole of Toxoplasma gondii.

The obligate intracellular parasite Toxoplasma gondii produces a nucleoside triphosphate hydrolase (NTPase) (nucleoside-triphosphatase, EC 3.6.1.15) activable by dithiol-containing compounds. We have isolated the genomic DNA for the NTPase from the RH strain of Toxoplasma and determined the nucleotide sequence of three tandemly arranged open reading frames termed NTP1, NTP2, and NTP3. We have also isolated and sequenced cDNAs for NTP1 and NTP3; no cDNA for NTP2 was obtained. The two cDNA clones encode proteins that are more than 97% identical at the amino acid level but significantly differ within two small domains, indicating the presence of NTPase isoforms. Both possess N-terminal signal sequences and two regions with partial homology to certain known ATP binding motifs: the glycine-rich loop common to many ATP binding proteins and the beta-phosphate binding domain found in the hexokinase-actin-hsp70 family. Antiserum against a NTP1-fusion protein immunoprecipitated NTPase activity from extracellular parasites that was increased in activity by treatment with dithiothreitol, confirming the identity of the cloned genes. By immunofluorescence, the NTPase is located in vesicular structures within the parasite, and in infected cells it is secreted into the vacuolar space and becomes partially associated with the parasitophorous vacuolar membrane. Since the vacuolar membrane is freely permeable to small molecules of < 1300 Da, host cell ATP may serve as a substrate for the NTPase and supply the energy for parasite-directed processes in the vacuolar space.