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T E Nash

Publications and source records attributed to T E Nash.

112 records · Page 7Linked to original sources
PubMedDate not supplied

Giardia lamblia: identification and characterization of a variant-specific surface protein gene family.

Giardia lamblia trophozoites undergo antigenic variation by modulating the expression of variant-specific surface proteins (VSP), which are encoded by a number of small multigene families. We characterized the genomic copy of the VSP gene expressed by the cloned trophozoite line H7, derived from the isolate GS/M, in addition to a related, but nonexpressed, family member. The coding regions of the two genes encode closely related polypeptides (86% identity). However, differences in the coding region of these genes reside solely in an 873 bp segment. Only four differences were found between the 5' flanking sequences (465 bp). The proximal 205 base pairs downstream from the coding regions were identical, but thereafter the sequences diverged (37% identity over the next 391 bp). Mapping studies indicated that no other VSP gene was located within 4 kb pairs of the expressed H7 VSP gene, and transcripts from the nonexpressed gene were detected in neither GS/H7 nor heterogeneous trophozoites populations derived from this cloned line. Any mechanisms responsible for the differential expression of VSP genes must reconcile the near identity of DNA sequences that flank the coding regions of expressed and nonexpressed VSP genes.

Amino Acid Sequence↗
PubMedDate not supplied

Lipid requirements and lipid uptake by Giardia lamblia trophozoites in culture.

To better understand the lipid requirements of Giardia lamblia trophozoites and the mechanisms of lipid uptake, we supplemented serum-free TYI-S-33 medium with lipids incorporated into different lipid carriers. We found that serum lipoproteins, beta-cyclodextrins, and bile salts are able to supply cholesterol and phospholipids to Giardia and to support the multiplication of the parasite in vitro. The growth rates obtained with different lipoproteins or bile salts and lipid mixtures were similar to that in standard culture medium containing serum. Pulse labelling experiments using fluorescent lipid analogs demonstrated that Giardia can take up lipids from lipoproteins, beta-cyclodextrins, or bile salt micelles, but with different kinetics, and that bile salts greatly facilitated lipid transfer from lipoproteins and cyclodextrins to the parasite surface. The binding of different radioiodinated lipoprotein classes to the trophozoite surface, inhibition of lipoprotein interiorization at 4 degrees C or by cytochalasin D, and incorporation studies using fluorescent LDL suggested that a small component of lipid uptake by trophozoites was likely due to endocytosis of lipoproteins.

Animals↗
PubMedDate not supplied

The efficacy of oxamniquine in acute schistosomiasis: a clinical analysis of 28 treated patients.

During the summer of 1980, acute Manson's Schistosomiasis occurred in 28 pediatric patients, swimming in two ponds with no watershed connections between them, in the rural area of Juncos and Cidra, Puerto Rico. Clinical and immunological events were studied and Oxamniquine (Vansil, Pfizer) was administered to all of them and followed closely for 3 years. Fever and general malaise recorded in 93% of the patients, diarrhea and abdominal pain in 68% and urticaria or facial edema in 64%. Hepato and/or splenomegaly was recorded in 71% of them. Twenty seven of the patients had evidence of immunoserological activity against adult schistosomal antigens (GASP and PSAP). Two patients had intense immunologic activity, even before the recovering of fresh Schistosoma mansoni eggs in their stool. This was a response to GASP and PSAP antigens. When they started passing fresh eggs of schistosoma and COP (Circumoval Precipitation Test) turned positive, their clinical status worsened and antibodies to GASP antigen increased two fold. The oviposition phase elicited a strong antibody and immunological reaction with significant eosinophilia and cross reaction was observed between adult schistosomal and egg shell antigens. Severe clinical manifestations were seen in spite of low egg excretion. Oxamniquine was effective in obtaining a coprological cure and in altering the immunologic response as compared with other untreated groups in literature.

Acute Disease↗