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A Thai Acanthamoeba isolate named AS recovered from a corneal scraping of a keratitis patient was genotypically determined as T4. AS trophozoites were used for studying Acanthamoeba-induced apoptosis in mouse neuroblastoma NA cells during in vitro co-cultivation. The Acanthamoeba-exposed NA cells showed signs of apoptosis including cell shrinkage, nuclear condensation and DNA fragmentation. The effect was confirmed by DNA laddering electrophoresis. Involvement of caspase enzymes and mitochondrial pro- and anti-apoptotic proteins (Bax and Bcl-2) in AS-induced apoptosis was determined. The use of Z-VAD-FMK, a pan-caspase inhibitor, significantly reduced the apoptotic effect, while Bax/Bcl-2 ratio analysis showed a significant increase in the expression of apoptotic proteins in AS-exposed NA cells. These results strongly indicated that apoptosis induced by AS trophozoites is caspase-dependent and is mediated by over-expression of pro-apoptotic proteins in the mitochondrial pathway. This is the first report on the role of Bax in mediating apoptosis induced by Acanthamoeba.

The mechanism of rosette formation of uninfected erythrocytes with Plasmodium falciparum-infected erythrocytes is rarely described. In this study, rosetting of uninfected normal erythrocytes with infected erythrocytes significantly reduced after treatment of the uninfected erythrocytes with neuraminidase. In contrast, the rosetting property of the infected erythrocytes was abolished by trypsinization but not by neuraminidase. The in vitro rosetting model showed that uninfected thalassemic erythrocytes poorly formed rosettes with infected normal erythrocytes when compared with normal erythrocytes of the same blood group. A rosetting parasite clone showed significant reduction in rosetting with thalassemic erythrocytes of all blood groups, however, this reduction was not obvious when the wild P. falciparum isolates were studied. These results suggest that while parasites from a single clone can rosette with uninfected erythrocytes via carbohydrate component, there is more than one type of receptor on uninfected erythrocytes involved in rosette formation with the heterogeneous populations of the wild P. falciparum isolates.

Hemoglobinopathies have a protective role in malaria that appears to be related to alterations in red blood cell (RBC) properties. Thalassemic RBCs infected with Plasmodium falciparum showed greatly reduced cytoadherence and rosetting properties as well as impaired growth and multiplication. A significant decrease in the levels of falciparum antigens associated with the membrane of infected beta-thalassemic RBCs was observed at trophozoite/schizont stage, but not young ring stage. This reduction was shown when a cytoadherence inhibitory monoclonal antibody, but not a noninhibitory pooled immune serum, was used. These observations suggest that protection against malaria in thalassemia is caused by both reduced parasitemias and altered adherence properties of the infected thalassemic RBCs that promote enhanced clearance of the parasite from the circulation.

A sensitive enzyme-linked immunosorbent assay is described for the detection of immunoglobulin G antibody to Gnathostoma antigen in the sera of patients with intermittent cutaneous migratory swelling who were suspected of being infected by the tissue nematode Gnathostoma spinigerum. The antigen used was a crude somatic aqueous extract of the third larval stage obtained from naturally infected eels. The 1:320 dilution of all sera from 46 patients gave enzyme-linked immunosorbent assay values above the mean (+2 standard deviations) of normal healthy controls, which was arbitrarily used as a cutoff point. The sera from patients suspected of being infected by another tissue nematode, Angiostrongylus cantonensis, as well as from patients with intestinal roundworm infections, also reacted weakly in the test system used in this study. Nonetheless, when the assay was carried out using both Gnathostoma and Angiostrongylus antigens simultaneously, it appeared to be a reliable laboratory test that can be used to support a clinical diagnosis of gnathostomiasis in patients with intermittent cutaneous migratory swelling.

Thirteen members of a family of 182 demonstrated laboratory or historical evidence of thrombocytopenia. The onset of bleeding symptoms occurred around the age of 6 years, followed by spontaneous remission of symptoms but not thrombocytopenia in early adult life. Treatment ranged from symptomatic care to long-term steroid therapy or splenectomy. The disorder is inherited in an X-linked recessive manner but appears to be distinct from the Wiskott-Aldrich syndrome in other respects.