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At least 91 records · Page 5Linked to original sources
PubMed1982

Anisakiasis: nematode infestation producing small-bowel obstruction.

A case of small-bowel obstruction occurred secondary to an uncommon parasitic disease, anisakiasis. Intestinal obstruction is a rare manifestation of this disease. Anisakiasis may be seen initially with nausea and vomiting or may mimic acute appendicitis or Crohn's disease. The predisposing factor in all cases is the ingestion of raw fish, and the disease is preventable by cooking fish at greater than 60 degrees C for a short time or by freezing at less than -20 degrees C for more than 24 hours. Anisakiasis should be considered in the differential diagnosis of small-bowel obstruction in patients whose diet includes raw fish.

Adult↗
PubMed1997

Polymerase chain reaction-linked single-strand conformation polymorphism of ribosomal DNA to fingerprint parasites.

To overcome limitations of the morphological identification of some parasites (and their different developmental stages) to species, we have established a polymerase chain reaction-linked single-strand conformation polymorphism technique (PCR-SSCP) utilizing the second internal transcribed spacer (ITS-2) of ribosomal (r)DNA. This spacer was specifically chosen in the study of strongylid and ascarid nematodes because it is known to provide reliable species markers. The ITS-2 from individual parasites was amplified by PCR, then denatured and subjected to electrophoresis on a mutation detection enhancement (MDE) (nondenaturing) gel matrix. PCR-SSCP analysis showed that the single-strand ITS-2 patterns produced allowed the accurate identification of species. The method also allowed the display of (low-level) variation in patterns within some species between different geographical isolates. These findings demonstrate the usefulness of PCR-SSCP of ITS-2 for the identification of nematode species and indicate its potential for resolving variation in the ITS-2 sequence within species.

Animals↗
PubMed1998

Detection of sequence variation in parasite ribosomal DNA by electrophoresis in agarose gels supplemented with a DNA-intercalating agent.

This study evaluated the use of a commercially available DNA intercalating agent (Resolver Gold) in agarose gels for the direct detection of sequence variation in ribosomal DNA (rDNA). This agent binds preferentially to AT sequence motifs in DNA. Regions of nuclear rDNA, known to provide genetic markers for the identification of species of parasitic ascarid nematodes (order Ascaridida), were amplified by polymerase chain reaction (PCR) and subjected to electrophoresis in standard agarose gels versus gels supplemented with Resolver Gold. Individual taxa examined could not be distinguished reliably based on the size of their amplicons in standard agarose gels, whereas they could be readily delineated based on mobility using Resolver Gold-supplemented gels. The latter was achieved because of differences (approximately 0.1-8.2%) in the AT content of the fragments among different taxa, which were associated with significant interspecific differences (approximately 11-39%) in the rDNA sequences employed. There was a tendency for fragments with higher AT content to migrate slower in supplemented agarose gels compared with those of lower AT content. The results indicate the usefulness of this electrophoretic approach to rapidly screen for sequence variability within or among PCR-amplified rDNA fragments of similar sizes but differing AT contents. Although evaluated on rDNA of parasites, the approach has potential to be applied to a range of genes of different groups of infectious organisms.

Animals↗
PubMed1998

Single-strand conformation polymorphism (SSCP)-based mutation scanning approaches to fingerprint sequence variation in ribosomal DNA of ascaridoid nematodes.

In this study, we assessed single-strand conformation polymorphism (SSCP)-based approaches for their capacity to fingerprint sequence variation in ribosomal DNA (rDNA) of ascaridoid nematodes of veterinary and/or human health significance. The second internal transcribed spacer region (ITS-2) of rDNA was utilised as the target region because it is known to provide species-specific markers for this group of parasites. ITS-2 was amplified by PCR from genomic DNA derived from individual parasites and subjected to analysis. Direct SSCP analysis of amplicons from seven taxa (Toxocara vitulorum, Toxocara cati, Toxocara canis, Toxascaris leonina, Baylisascaris procyonis, Ascaris suum and Parascaris equorum) showed that the single-strand (ss) ITS-2 patterns produced allowed their unequivocal identification to species. While no variation in SSCP patterns was detected in the ITS-2 within four species for which multiple samples were available, the method allowed the direct display of four distinct sequence types of ITS-2 among individual worms of T. cati. Comparison of SSCP/sequencing with the methods of dideoxy fingerprinting (ddF) and restriction endonuclease fingerprinting (REF) revealed that also ddF allowed the definition of the four sequence types, whereas REF displayed three of four. The findings indicate the usefulness of the SSCP-based approaches for the identification of ascaridoid nematodes to species, the direct display of sequence variation in rDNA and the detection of population variation. The ability to fingerprint microheterogeneity in ITS-2 rDNA using such approaches also has implications for studying fundamental aspects relating to mutational change in rDNA.

Animals↗
PubMed2002

Identification of anisakid nematodes from the Southern Baltic Sea using PCR-based methods.

Four common species of Baltic anisakids Anisakis simplex, Hysterothylacium auctum, Contracaecum osculatum from fish (the last one also from the grey seal) and C. rudolphii from cormorants were examined using PCR-RFLP technique for working out the method allowing their identification and differentiation. A fragment of nuclear DNA containing intergenic regions (ITS-1 and ITS-2) of ribosomal DNA together with adjacent sequences of genes coding 18S and 28S rRNA (in total; approximately 1500 bp) was amplified and the products were digested using three endonucleases Hin fI, Hae III and Pvu II. Digestion with Hin fI endonuclease enabled species identification and differentiation between all nematode species studied. Digestion with Hae III endonuclease enabled identification of A. simplex and H. auctum while electrophoretic patterns obtained for both Contracaecum species were similar (differentiation between A. simplex, H. auctum and the genus Contracaecum). Pvu II endonuclease was not suitable to this purpose. On the basis of nucleotide sequences obtained, the pairs of species-specific primers were designed for each species studied. By the use of these pairs of primers the species-specific PCR reactions were carried out. The sizes of specific products were: 486 bp for A. simplex, 491 bp for C. osculatum, 505 bp for C. rudolphii and 663 bp for H. auctum. The methods presented herein can be useful in diagnostics of human anisakidosis, especially when parasites are disrupted.

Animals↗