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Biomedical subjects

D Blair

Publications and source records attributed to D Blair.

At least 55 records · Page 3Linked to original sources
PubMed1998

Relative merits of nuclear ribosomal internal transcribed spacers and mitochondrial CO1 and ND1 genes for distinguishing among Echinostoma species (Trematoda).

Cryptic species, belonging to the 37 collar-spine Echinostoma group, were distinguished using nuclear rDNA ITS (884 bases) and mtDNA CO1 (257 bases) and ND1 (530 bases) sequences. Sequences were obtained from five 37 collar-spine species, Echinostoma trivolvis, E. paraensei, E. caproni, E. revolutum and E. sp.I, a parthenogenetic isolate from Africa. Three geographic isolates of E. caproni were compared. Average sequence divergence among the 37 collar-spine species range from 2.2% in the rDNA ITS through 8% for the CO1 and 14% for the ND1. In addition, genes were sequenced from 2 non 37 collar-spine species, E. hortense and an undescribed Australian species, E. sp. (Aus). For each gene, distances of terminals from a predicted ancestral sequence were calculated. These indicated that ND1 is diverging significantly faster than the other 2 regions. In the CO1 gene most substitutions are synonymous and saturation has been reached for the majority of pairwise comparisons. The ND1 gene exhibits greater pairwise divergence but less evidence of saturation due to weaker conservation of first and second codon positions. The ITS has no amino acid coding constraints and displays no evidence of saturation. Although all 3 regions successfully distinguished the nominal species, ND1 appears to be the most informative region for investigating relationships within the 37 collar-spine group.

Animals↗
PubMed1998

Intra- and inter-specific variation in nuclear ribosomal internal transcribed spacer 1 of the Schistosoma japonicum species complex.

The first internal transcribed spacer (ITS1) of the nuclear ribosomal DNA repeat was sequenced for members of the Schistosoma japonicum species complex (S. malayensis, S. mekongi and 2 geographical isolates of S. japonicum). The ITS1 is composed of 3 distinct regions: the 5' end (23 nucleotides); a tract of approximately 90-140 nucleotides, which occurs up to 7 times in tandem, the number varying even within an individual in all species investigated in this study; the 3' region (378 nucleotides), which lacks repeats. There is size and sequence variation among copies of the ITS1 repeat within a single individual. The relative abundances of size variants of ITS1 in S. japonicum have been ascertained by hybridizing genomic digests with an ITS1 probe. Multiple repeats and intra-individual variation in numbers and abundance of these is a feature of the Asian schistosomes, but not generally of African schistosomes. Possible reasons for this difference in ITS1 between African and Asian schistosomes are discussed. The ITS1 repeat sequences described for African schistosomes are different to, and cannot be aligned with, those from the Asian species described here, whereas the remainder of the ITS1 can be aligned quite easily.

Animals↗
PubMed1998

Redescription of Hapalotrema mistroides (Monticelli, 1896) and Hapalotrema synorchis Luhman, 1935 (Digenea: Spirorchidae), with comments on other species in the genus.

Hapalotrema mistroides (Monticelli, 1896) Stiles and Hassall, 1908 and Hapalotrema synorchis Luhman, 1935 are redescribed using specimens from the loggerhead turtle. Caretta caretta (L.). The redescription of H. mistroides is based on specimens collected by Looss and described as Hapalotrema constrictum Leared, 1862 and renamed Hapalotrema loossi Price, 1934, which is now considered a junior synonym of H. mistroides. Hapalotrema orientalis Takeuti, 1942 is considered a junior synonym of Hapalotrema synorchis. The redescriptions are consistent with the originals but provide an unreported range of variation while adding new information about the reproductive systems. Reexamination of Hapalotrema dorsopora Dailey, Fast, and Balazs, 1993 confirms the presence of a reproductive system typical for the genus and the absence of a dorsal genital pore; therefore, H. dorsopora is reduced to a junior synonym of Hapalotrema mehrai Rao, 1976. Four valid species of Hapalotrema are recognized: H. mistroides. H. synorchis, H. postorchis, and H. mehrai, and a key to the species is provided.

Animals↗
PubMed1997

Australian bat lyssavirus infection in three fruit bats from north Queensland.

We report the case findings of Australian bat lyssavirus infection in two black flying foxes (Pteropus alecto) and one little red flying fox (Pteropus scapulatus) from north Queensland between January 1995 and August 1996. Although the P. alecto case in January 1995 is the first recognised case of Australian bat lyssavirus infection in Australia, this was a retrospective diagnosis made after identification of the index case at Ballina in May 1996. Eight persons had exposure to the three bats. Serum antibodies to classical rabies virus were measured in six of these persons; the only one seropositive was a veterinarian who had previously been vaccinated against rabies. Six persons received rabies vaccine following exposure. None of the in-contact humans developed signs of lyssavirus infection. For people exposed to Australian bat lyssavirus-positive bats who have not been scratched or bitten or had mucosal contamination by these bats, we suggest a post-exposure regime of five inoculations of the human diploid cell inactivated rabies vaccine.

Animals↗
PubMed1997

Mitochondrial DNA and nuclear DNA indicate that the Japanese Fasciola species is F. gigantica.

For elucidation of the taxonomic status of the Japanese Fasciola species, whole mitochondrial DNA of Fasciola hepatica from Australia, F. gigantica from Malaysia, and Fasciola sp. from Japan was digested with three four-base-cutting endonucleases: HinfI, MspI, and RsaI. The resulting digestion patterns showed that for each enzyme there were some bands specific for each geographical isolate and that the Japanese Fasciola sp. shared more bands with F. gigantica than with F. hepatica. Nucleotide sequences of two regions, the second internal transcribed spacer (ITS2) of the nuclear ribosomal RNA cluster and mitochondrial cytochrome c oxidase subunit I (COI), were also compared among them. The ITS2 sequence was highly conserved among the three isolates. F. gigantica and the Japanese Fasciola sp. were identical, but they differed from the Australian F. hepatica at six sites, one of which was a deletion. The COI sequence was less conserved but implied a similar relationship between the isolates. There seems no reason to regard the Japanese Fasciola sp. as anything other than a strain of F. gigantica.

Animals↗
PubMed1997

Molecular evidence for the synonymy of three species of paragonimus, P. ohirai miyazaki, 1939, P. iloktsuenensis chen, 1940 and P. sadoensis miyazaki et al., 1968

The Paragonimus ohirai group, named after P. ohirai Miyazaki, 1939, consists of three nominal species. Paragonimus iloktsuenensis Chen, 1940 and P. sadoensis Miyazaki et al., 1968, the other members of the group, were proposed primarily because of perceived differences in metacercarial morphology and/or host preferences. It has long been recognized that adults of the three were virtually indistinguishable. With the application of genetic techniques, it has become clear that the three forms can exchange genes freely, and that differences in metacercarial morphology constitute a polymorphism probably due to a single gene inherited in Mendelian fashion. Here, additional genetic data (DNA sequences from the second internal transcribed spacer of the nuclear ribosomal gene cluster and from the mitochondrial cytochrome c oxidase subunit I gene) are presented in support of the synonymy.

Journal Article↗
PubMed1997

Geographical genetic structure within the human lung fluke, Paragonimus westermani, detected from DNA sequences.

Nucleotide sequences were obtained for the second internal transcribed spacer of the ribosomal gene repeat and for part of the mitochondrial-cytochrome c oxidase subunit I gene from geographical isolates of Paragonimus westermani from Japan, China, Korea, Taiwan, the Philippines, peninsular Malaysia and Thailand. Sequences were obtained from several other species of Paragonimus for comparative purposes. Two groups were recognized within P. westermani: an NE group (China, Japan, Korea, Taiwan) which was relatively uniform and included both diploid and triploid forms, and a southern group (Malaysia, Thailand, Philippines), members of which were genetically distant from one another. According to both ITS2 and COI data, genetic distances among P. westermani isolates equalled or exceeded those between some distinct species of Paragonimus. The ITS2 sequences were conserved relative to COI sequences. Substitutions among the latter may be approaching saturation within the genus Paragonimus.

Animals↗
PubMed1997

Observations of fibropapillomatosis in green turtles (Chelonia mydas) in Indonesia.

OBJECTIVE: To determine the prevalence and manifestations of fibropapillomatosis in green turtles in Indonesia, to identify any relationship between fibropapillomatosis and concurrent parasitic infection, to ascertain the effect of fibropapillomatosis on health, and to examine whether environment might have an effect on the prevalence of fibropapillomatosis. PROCEDURE: 4407 green turtles (Chelonia mydas) and 401 hawksbill turtles (Eretmochelys imbricata) were examined. The occurrence of fibropapillomatosis was correlated with sex, maturity, curved carapace length, body weight/curved carapace length ratio, the number and distribution of tumours on the skin, parasite burdens, some haematological variables and the region of capture. RESULTS: Fibropapillomatosis was seen only in green turtles, and the overall prevalence in these was 21.5%. This prevalence increased with the curved carapace length up to 85 cm. The average number of tumours per affected turtle was 5 +/- SD 4.1 (range, 1 to 29), and was negatively correlated with the body weight/curved carapace length ratio (rs = -0.8; P = 0.001). The red blood cell count in turtles with fibropapilloma was lower than in non-fibropapilloma turtles captured and examined at the same time (P = 0.001). The prevalence of fibropapilloma in turtles captured near densely populated, industrial regions (26.3%) was greater than in turtles from sparsely populated areas (17.7%). CONCLUSION: Fibropapillomatosis in green sea turtles in Indonesia is of moderate occurrence: young mature turtles (curved carapace length = 85 cm) are most frequently affected. Fibropapilloma adversely affects health of turtles. Fluke infestation seems not to be a causal factor, but viral infection, perhaps with concurrent stress of environmental origin, seems likely.

Age Distribution↗
PubMed1997

Efficacy of praziquantel in the treatment of green sea turtles with spontaneous infection of cardiovascular flukes.

OBJECTIVE: To assess the efficacy of praziquantel as a treatment for cardiovascular flukes in turtles. PROCEDURE: Six green sea turtles (Chelonia mydas) spontaneously infected with cardiovascular flukes (Digenea: Spirorchiidae) were treated orally with praziquantel, and necropsied 3 or 7 days later to look for flukes in the heart and major blood vessels. Six similar animals were maintained as untreated controls. RESULTS: Absence of flukes in treated, but not control turtles, indicated that a one day course of treatment at a dose rate of 3 x 50 mg/kg body weight is effective. CONCLUSION: This result should be of value for preventing disease in wild caught green turtles introduced into farms or aquaria.

Administration, Oral↗
PubMed1997

The changing face of medicine.

As the trend toward managed care and other outside involvement in the medical decision-making process continues to grow, so does concern over patient care issues. The Society is deeply concerned about physician loss of control in that decision-making process, and is taking significant actions to help physicians regain control.

Attitude of Health Personnel↗
PubMed1996

Evolutionary biology of parasitic platyhelminths: The role of molecular phylogenetics.

As our appreciation of the diversity within the flatworms has grown, so too has our curiosity about the ways in which these varied creatures are related to one another. In particular, the parasitic groups (trematodes, cestodes and monogeneans have been the focus of enquiry. Until recently, morphology, anatomy and life histories have provided the raw data for building hypotheses on relationships. Now, ultrastructural evidence, and most recently, molecular data from nucleic acid sequences, have been brought to bear on the topic. Here, David Blair, Andrés Campos, Michael Cummings and Juan Pedro Laclette discuss the ways in which molecular data, in particular, are helping us recognize the various lineages of flatworms.

Journal Article↗
PubMed1996

Molecular phylogeny of Schistosoma species supports traditional groupings within the genus.

Phylogenetic relationships among 9 blood flukes (7 schistosome species, a spirorchid, and a sanguinicolid) were inferred from nucleotide sequences of the D1 domain of large subunit rRNA and the V4 region of small subunit rRNA. These sequences were more conserved than those examined by previous authors and thus may provide insight into deeper-level relationships. Analyzed separately and combined by 3 methods, these data yielded congruent trees that were well supported by bootstrap resampling. The traditional groups of schistosome species based on egg type were supported. Schistosoma japonicum and Schistosoma mekongi were distinct from the remaining Schistosoma species. Schistosoma spindale (from India and southeast Asia) clustered strongly with the African species to the exclusion of the other Asian species, S. japonicum and S. mekongi. Schistosoma spindale may have been brought to India and southeast Asia from Africa by early humans. Statistical tests revealed only weak evidence for the operation of a molecular clock in the V4 sequence; no evidence was found for this in the D1 domain.

Africa↗
PubMed1996

Two new species of Uterotrema (Digenea: Spirorchidae) parasitic in Emydura krefftii (Testudines: Chelidae) from Australia.

Two new species of Uterotrema (Digenea: Spirorchidae) are described from Emydura krefftii in northern Queensland, Australia. Both new species are smaller than the only previously described member of the genus and possess an oral sucker/ventral sucker ratio > 1. Uterotrema burnsi n. sp. possesses a thin, elongate uterus that is 25% of the total body length. The uterus of Uterotrema kreffti n. sp. is shorter, and it possesses vitellaria and a vitelline reservoir, neither of which were reported in the type species. Although reported here as distinct species they may represent a single species that sequentially changes reproductive roles during development in the definitive host.

Animals↗
PubMed1995

A molecular phylogeny of the human schistosomes.

Members of the genus Schistosoma are generally grouped on the basis of egg morphology, intermediate host specificity, and geographic origin. We have tested hypotheses based on these groupings by phylogenetic analysis of nuclear ribosomal (ITS2) and mitochondrial (COI) nucleotide sequences. Both mitochondrial and nuclear DNA data strongly support "traditional" hypotheses that (a) members of the Schistosoma haematobium group form a monophyletic clade, (b) members of the S. mansoni group form a monophyletic clade, (c) S. japonicum and S. mekongi form a monophyletic group relative to other schistosomes, and (d) the African schistosomes form a clade to the exclusion of the two Asian species.

Animals↗