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Acanthamoeba is a genus of free-living protozoa that can cause sight- and life-threatening diseases in man. Its control is still problematic due to the lack of effective and nontoxic acanthamoebicidal agents. Herein, we report the first finding of an in vitro killing effect of fusaric acid and dehydrofusaric acid, isolated from metabolites of the Fusarium fujikuroi species complex Tlau3, on Acanthamoeba trophozoites isolated from two clinical (AS, AR) and two soil (S3, S5) samples. AS, AR, and S3 were classified as members of the T4 genotype, whereas S5 belongs to T5. The fungal extract was found to exhibit acanthamoebicidal activity, and activity-guided fractionation led to the isolation and identification of active principles, fusaric acid and dehydrofusaric acid. Their effects were in concentration- and time-dependent manners. Fusaric acid and dehydrofusaric acid showed IC₅₀ values against AS trophozoites of 0.31 and 0.34 µM, respectively. Commercial fusaric acid displayed the same acanthamoebicidal activity as that of the isolated fusaric acid, and therefore, commercial fusaric acid was used throughout this study. IC₅₀ values of commercial fusaric acid against AR, S3, and S5 trophozoites were 0.33, 0.33, and 0.66 µM, respectively. Fusaric acid calcium salt has a history of usage as a hypotensive agent in humans with no observed toxicity. The present study suggests that fusaric acid may serve as a starting point for the development towards therapeutic and environmental acanthamoebicides with low toxicity to humans.

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.

cDNA and genomic DNA of Giardia intestinalis have been cloned in pUC vectors and used to express Giardia antigens in Escherichia coli. Several expression libraries have been produced and positive clones identified by immuno-colony assays with antisera raised against whole parasites and partially purified antigen(s). Those clones which express G. intestinalis antigens have been used to raise antisera in mice and the antisera used in immunofluorescence assays. The proteins expressed by the clones have been shown to represent a 32 kDa protein of the flagellae and axonemes, a protein associated with the spiral part of the ventral disc, proteins covering the surface of the trophozoite or associated with the coat, and other proteins associated with axonemes of posterolateral flagellae, kinetosomes and funis, and the anterolateral axonemes. mRNA was purified from G. intestinalis and translated in a cell free lysate. A rabbit antiserum raised against trophozoites immunoprecipitated several translation products while an antiserum raised against a purified 32 kDa protein only immunoprecipitated this protein. G. intestinalis rRNA subunits also were examined in the course of mRNA purification. Two rRNA species were evident, the small rRNA and the post-transcriptionally processed large rRNA.

In certain hill tribal villages the authors conducted a study of opium use in correlation with health, economic, and sociocultural status. The reasons for and the circumstances surrounding opium use and addiction vary in different tribes. The use of opium as a drug for treatment of illnesses and as a psychotropic drug is commonly found in many hill tribes. Recreational and social uses of opium are not found to be as extensive as previously believed. Nevertheless, there are a number of contexts in which opium is socially used.

Protein profiles of somatic extracts from different developmental stages and excretory and secretory products of third-state larvae of Angiostrongylus cantonensis were analyzed and characterized by polyacrylamide gel electrophoresis in sodium dodecyl sulfate under both reduced and unreduced conditions. Immunological identification of common and stage-specific antigens was determined by radioimmunoprecipitation using chronically infected rat serum and antisera from rats immunized with somatic extracts of third-stage larvae and adult female worms. The somatic extracts of first-and third-stage larvae and of adult worms were found to be highly complex, each consisting of more than 20 different peptides with molecular weights varying from higher than 130,000 to 8,200 daltons. Most proteins were composed of single polypeptide chains. Polypeptides with molecular weights of 80,000, 39,500 and 22,000 daltons were present in more than one developmental stages and were antigenically related. Those with molecular weight of 15,500 dalton, was present primarily in L3S and its possible usefulness in immunodiagnosis of infection that occurs in man was discussed.

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.

Attempts were made to induce acquired immunity against Angiostrongylus cantonensis infection by immunizing rats with somatic (L3S) and metabolic (L3ES) antigens from third-stage larvae and with somatic antigen from adult female worms (FACE) via either a combined intraperitoneal and oral (IP-OR-OR) or subcutaneous (SC-SC-SC) route. The most effective mean in inducing protection was the administration of L3S by the IP-OR-OR route, as judged from reduced mortality, prolonged survival periods and/or reduced worm burdens. Such a protocol reduced mortality to below 20% of the unimmunized controls. The worm burden of the L3S-immunized rats was only about 25% of the control value and the survival period was at least double. However, judging from gross morphology, the absence of stunted growth and unimpaired ficundity of the worms that developed into adult stage, it appears that those worms that survived had normal development. The latter observation is in contrast to that noted with FACE immunization which seemed to affect also the growth and development of worms that survived into adult stage.

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.