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R C Thompson

Publications and source records attributed to R C Thompson.

At least 55 records · Page 3Linked to original sources
PubMed2000

Sequence differences in the diagnostic target region of the oocyst wall protein gene of Cryptosporidium parasites.

Nucleotide sequences of the Cryptosporidium oocyst wall protein (COWP) gene were obtained from various Cryptosporidium spp. (C. wrairi, C. felis, C. meleagridis, C. baileyi, C. andersoni, C. muris, and C. serpentis) and C. parvum genotypes (human, bovine, monkey, marsupial, ferret, mouse, pig, and dog). Significant diversity was observed among species and genotypes in the primer and target regions of a popular diagnostic PCR. These results provide useful information for COWP-based molecular differentiation of Cryptosporidium spp. and genotypes.

Animals↗
PubMed2000

Cryptosporidium spp. in domestic dogs: the "dog" genotype.

Genetic and phylogenetic characterization of Cryptosporidium isolates at two loci (18S rRNA gene and heat shock gene) from both Australian and United States dogs demonstrated that dog-derived Cryptosporidium isolates had a distinct genotype which is conserved across geographic areas. Phylogenetic analysis provided support for the idea that the "dog" genotype is, in fact, a valid species.

Animals↗
PubMed2000

Phylogenetic relationships of Cryptosporidium parasites based on the 70-kilodalton heat shock protein (HSP70) gene.

We have characterized the nucleotide sequences of the 70-kDa heat shock protein (HSP70) genes of Cryptosporidium baileyi, C. felis, C. meleagridis, C. muris, C. serpentis, C. wrairi, and C. parvum from various animals. Results of the phylogenetic analysis revealed the presence of several genetically distinct species in the genus Cryptosporidium and eight distinct genotypes within the species C. parvum. Some of the latter may represent cryptic species. The phylogenetic tree constructed from these sequences is in agreement with our previous results based on the small-subunit rRNA genes of Cryptosporidium parasites. The Cryptosporidium species formed two major clades: isolates of C. muris and C. serpentis formed the first major group, while isolates of C. felis, C. meleagridis, C. wrairi, and eight genotypes of C. parvum formed the second major group. Sequence variations were also observed between C. muris isolates from ruminants and rodents. The HSP70 gene provides another useful locus for phylogenetic analysis of the genus Cryptosporidium.

Animals↗
PubMed2000

Molecular characterization of Cryptosporidium isolates obtained from human immunodeficiency virus-infected individuals living in Switzerland, Kenya, and the United States.

A total of 22 Cryptosporidium isolates from human immunodeficiency virus-infected patients from Kenya, Switzerland, and the United States were examined at three genetic loci: the 18S ribosomal DNA, HSP-70, and acetyl coenzyme A synthetase genes. Four distinct Cryptosporidium genotypes were identified: (i) the Cryptosporidium parvum "human" genotype, (ii) the C. parvum "cattle" genotype, (iii) Cryptosporidium felis, and (iv) Cryptosporidium meleagridis. This is the first report of C. meleagridis in a human host. These results and those of others indicate that immunocompromised individuals are susceptible to a wide range of Cryptosporidium species and genotypes. Future studies are required to understand the full public health significance of Cryptosporidium genotypes and species in immunocompromised hosts.

AIDS-Related Opportunistic Infections↗
PubMed2000

Localization of glucokinase-like immunoreactivity in the rat lower brain stem: for possible location of brain glucose-sensing mechanisms.

Pancreatic glucokinase (GK) is considered an important element of the glucose-sensing unit in pancreatic beta-cells. It is possible that the brain uses similar glucose-sensing units, and we employed GK immunohistochemistry and confocal microscopy to examine the anatomical distribution of GK-like immunoreactivities in the rat brain. We found strong GK-like immunoreactivities in the ependymocytes, endothelial cells, and many serotonergic neurons. In the ependymocytes, the GK-like immunoreactivity was located in the cytoplasmic area, but not in the nucleus. The GK-positive ependymocytes were found to have glucose transporter-2 (GLUT2)-like immunoreactivities on the cilia. In addition, the ependymocytes had GLUT1-like immunoreactivity on the cilia and GLUT4-like immunoreactivity densely in the cytoplasmic area and slightly in the plasma membrane. In serotonergic neurons, GK-like immunoreactivity was found in the cytoplasm and their processes. The present results raise the possibility that these GK-like immunopositive cells comprise a part of a vast glucose-sensing mechanism in the brain.

Animals↗
PubMed2000

Detection of the Cryptosporidium parvum "human" genotype in a dugong (Dugong dugon).

The Cryptosporidium "human" genotype was identified in a paraffin-embedded tissue section from a dugong (Dugong dugon) by 2 independent laboratories. DNA sequencing and polymerase chain reaction/restriction fragment length polymorphism analysis of the 18S ribosomal RNA gene and the acetyl CoA synthethase gene clearly identified the genotype as that of the Cryptosporidium variant that infects humans. This is the first report of the human Cryptosporidium genotype in a nonprimate host.

Acetate-CoA Ligase↗
PubMed2000

Superficial temporal artery to middle cerebral artery bypass and external carotid reconstruction for carotid restenosis after angioplasty and stent placement.

The recent proliferation of endovascular treatment of carotid atherosclerotic disease will increase the number of patients who require treatment for recurrent carotid stenosis after angioplasty and stent placement. The optimal management of these patients has not yet been defined. We describe a 66-year-old woman who required 2 surgical procedures for recurrent in-stent carotid stenosis. She experienced numerous transient ischemic attacks 5 months after left extracranial internal carotid artery angioplasty and stenting for asymptomatic stenosis. Angiography showed high-grade in-stent restenosis, left intracranial carotid artery stenosis, and poor collateral flow to the left middle cerebral artery circulation. The patient underwent a superficial temporal artery to middle cerebral artery bypass, and the transient ischemic attacks resolved. Five months later, angiography showed progressive stenosis of the external carotid artery at the site of the stent. The patient underwent successful external carotid reconstruction with an on-lay patch. Extracranial-intracranial bypass grafting may be used successfully in the treatment of recurrent extracranial carotid artery stenosis after angioplasty and stent placement. Also, external carotid artery reconstruction at the site of an internal carotid artery stent can be performed safely.

Aged↗
PubMed2000

Synovial sarcoma. Large size predicts poor outcome.

A consecutive series of 38 patients with synovial sarcoma diagnosed and treated in a consistent fashion from 1976 to 1994 was reviewed for prognostic variables. The histologic specimens were reviewed and confirmed by one pathologist. There was a minimum 4-year followup for all surviving patients and no patients were lost to followup. The treatment protocol consisted of surgical excision with a wide or radical margin and limb preservation when possible. In those patients in whom the surgical margin was undefined or was less than a wide margin, perioperative radiation therapy was used. Four patients presented with metastatic disease and all died of their disease. Thirty-four patients had localized disease at presentation. Variables considered in stratifying outcomes included histologic grade, histologic subtype, surgical margin, presence or absence of local recurrence, age, and size of tumor. Of the 34 patients without metastasis there was a strong statistical association between size of tumor and survival: 17 patients with tumors less than 5 cm indiameter had a 100% survival, 12 patients with tumors 5 cm to 10 cm had a 75% survival, and five patients with tumors greater than 10 cm had a 20% survival. The authors urge that a multicenter trial for neoadjuvant chemotherapy be initiated for patients presenting with a synovial sarcoma greater than 10 cm in diameter.

Adolescent↗
PubMed1999

A comparison of the effects of a benzimidazole and the dinitroanilines against Leishmania infantum.

Leishmania infantum promastigotes and amastigotes were axenically cultured and exposed to the known tubulin binding compounds, the dinitroanilines, trifluralin, benfluralin, pendimethalin, oryzalin and the precursor of the dinitroanilines, chloralin, as well as isomers of chloralin and trifluralin and to the benzimidazole, albendazole. Drug induced inhibition was observed using [3H]thymidine uptake compared with untreated controls. In vitro analysis demonstrated a significant difference in the activity of five of the seven dinitroanilines between both life cycle stages of L. infantum. The amastigotes were 20-times more sensitive to chloralin and its isomer than to the dinitroanilines whereas the promastigotes were similar in sensitivity to the dinitroanilines and to chloralin and its isomer. This interesting finding suggests that the dinitroaniline precursors may have different target sites in the amastigotes to those within the promastigotes. Additionally, both chloralin and its isomer, and to a lesser extent benfluralin, caused a substantial stimulation of thymidine incorporation (up to 50%) at low concentrations. Dose response analysis suggests that the dinitroanilines may have more than one mode of action against L. infantum amastigotes and promastigotes. The inhibitory effects of the dinitroanilines against L. infantum vary from previous findings using the dinitroanilines against other Leishmania spp. The 348 base pair DNA sequence coding for beta-tubulin from amino acid residues 132 to 248 was obtained for L. infantum and used to compare the in vivo efficacy of albendazole with predicted activity based on beta-tubulin sequences of known benzimidazole sensitive protozoa. The use of beta-tubulin sequence as a predictive model of benzimidazole activity is discussed with particular reference to L. infantum.

Aniline Compounds↗
PubMed1999

Assessment of drugs against Cryptosporidium parvum using a simple in vitro screening method.

A rapid semi-quantitative screening method was devised for assessing the anticryptosporidial and cytotoxic effects of putative chemotherapeutic compounds. The method is suitable as an initial rapid screening procedure from which compounds demonstrating anticryptosporidial activity can be identified for further analysis. It has the advantages of speed, low cost and concurrent assessment of anticryptosporidial and cytotoxic effects and allows accurate determination of minimum lethal concentrations. Of the 71 compounds screened, six completely inhibited cryptosporidial growth at 1 microM (monensin, salinomycin, alborixin, lasalocid, trifluralin and nicarbazin) and a further eight showed significant anticryptosporidial activity at 1 or 20 microM (halquinol, bleomycin, suramin, mitomycin, doxycycline hydrochloride, toltrazuril, chloroquine phosphate and teniposide). Twelve compounds were found to have some degree of cytotoxicity at 1 microM and a further 12 at 20 microM.

Animals↗
PubMed1999

Lumbosacral chordoma. Prognostic factors and treatment.

STUDY DESIGN: Retrospective analysis. OBJECTIVES: To analyze the prognostic factors in patients with chordomas, the success of various treatments, the diagnostic value of open versus needle biopsy, the neurologic impairment after sacral nerve resection, and the clinical presentation and site of origin. SUMMARY OF BACKGROUND DATA: Staging of chordomas has not been of much value, compared with other bone tumors, because for chordomas, grade is similar, metastasis is infrequent at presentation, and the prognostic significance of size is uncertain. METHODS: A review of patients with chordoma from 1965 through 1996 found 23 cases (mean age of patients, 55 years). The mean follow-up was 84 months. Mean tumor size was 81 mm (range, 35-135 mm), location was lumbar (n = 6), S1 (n = 4), S2 (n = 3), S3 (n = 7), S4 (n = 2), and S5 (n = 1). RESULTS: No tumors were found in the higher sacrum (S1-S2) alone, without involvement of the lower sacrum. Survival analysis at 5 years showed overall survival (OS) 86%, continuous disease-free survival (CDFS) 58%, and local recurrence-free survival (LRFS) 60%. The location of tumor, defined by highest level of involvement (lumbar vs. sacrum) was of prognostic significance for OS (P = 0.01; log-rank test), CDFS (P = 0.036), but not for LRFS (P = 0.189). Results of multivariate regression showed that location was significant for OS (P = 0.007), CDFS (P = 0.008), and LRFS (P = 0.001). For patients with positive margins (n = 16), initial radiation correlated with longer CDFS (P = 0.002; Mantel-Cox) and LRFS (P = 0.005, Mantel-Cox), but was not significant for OS (P = 0.41). For patients who received no radiation, a positive margin correlated with a shorter CDFS (P = 0.04), a trend to shorter LRFS (P = 0.08), but no difference in OS. Therefore, both a tumor-free margin and initial radiation correlated with a longer survival. No patients had urinary or bowel dysfunction when both S3 nerves were preserved. If one S3 nerve was preserved, 1 of 3 patients had partial urinary incontinence and 2 of 3 patients required bowel medications. If both S3 nerves were resected, all patients required intermittent urinary catheterization and bowel medications. If both S2 nerves were resected, there was complete urinary and bowel incontinence. CONCLUSIONS: The highest level of tumor involvement was prognostically significant for OS, CDFS, and LRFS. Radiation was of value when complete excision was not achieved. Bilateral S3 nerve preservation is necessary to ensure retention of normal urinary and bowel function.

Adult↗
PubMed1999

Variation in Cryptosporidium: towards a taxonomic revision of the genus.

Cryptosporidium is an important cause of enteric disease in humans and other animals. Limitations associated with conventional diagnostic methods for cryptosporidiosis based on morphological features, coupled with the difficulty of characterising parasites isolated in the laboratory, have restricted our ability to clearly identify species. The application of sensitive molecular approaches has obviated the necessity for laboratory amplification. Such studies have found considerable evidence of genetic heterogeneity among isolates of Cryptosporidium from different species of vertebrate, and there is now mounting evidence suggesting that a series of host-adapted genotypes/strains/species of the parasite exist. In this article, studies on the molecular characterisation of Cryptosporidium during the last 5 years are reviewed and put into perspective with the past and present taxonomy of the genus. The predictive value of achieving a sound taxonomy for the genus Cryptosporidium with respect to understanding its epidemiology and transmission and controlling outbreaks of the disease is also discussed.

Animals↗
PubMed1999

Veterinary parasitology: looking to the next millennium.

'Veterinary parasitology' has traditionally been concerned with the control of parasites of livestock and companion animals, with emphasis on chemotherapy and immunoprophylaxis. This will continue, but there must be less reliance on chemical control; the development of alternative strategies will be a major goal over the next ten years. Here, Andrew Thompson takes an optimistic look at the challenges, strengths and opportunities for veterinary parasitology as we enter the next millennium. In the space available here, he can only 'scratch the surface' about what the future holds for veterinary parasitology, and will attempt to identify the major trends that are emerging, some of which will be the subject of future in-depth articles in Parasitology Today.

Animals↗
PubMed1999

Sequence and PCR-RFLP analysis of the internal transcribed spacers of the rDNA repeat unit in isolates of Cryptosporidium from different hosts.

The Cryptosporidium ITS1, 5.8S and ITS2 rDNA regions from a number of Cryptosporidium isolates from different hosts and geographical areas were cloned and sequenced in order to investigate the extent of sequence heterogeneity between human and cattle-derived isolates from different geographical locations and also between isolates of Cryptosporidium from different hosts such as cats, pigs, mice and a koala. Calf-derived isolates from different continents were virtually identical as were human-derived isolates from the UK and Australia. Genetic differences between Cryptosporidium isolates were extensive and were in fact greater than the level of nucleotide divergence between Toxoplasma gondii and Neospora caninum rDNA sequences. Based on the sequence information derived from this study, PCR-RFLP of the ITS1 region was undertaken in order to directly amplify and genotype Cryptosporidium isolates from different hosts. This PCR-RFLP approach can now be used for molecular epidemiology studies, circumventing the need for costly sequencing and allowing a wider range of genetically different isolates to be examined.

Animals↗