Biomedical subjects

Y Ortega

Publications and source records attributed to Y Ortega.

5 recordsLinked to original sources

PubMed2003

Landscape location affects genetic variation of Canada lynx (Lynx canadensis).

The effect of a population's location on the landscape on genetic variation has been of interest to population genetics for more than half a century. However, most studies do not consider broadscale biogeography when interpreting genetic data. In this study, we propose an operational definition of a peripheral population, and then explore whether peripheral populations of Canada lynx (Lynx canadensis) have less genetic variation than core populations at nine microsatellite loci. We show that peripheral populations of lynx have fewer mean numbers of alleles per population and lower expected heterozygosity. This is surprising, given the lynx's capacity to move long distances, but can be explained by the fact that peripheral populations often have smaller population sizes, limited opportunities for genetic exchange and may be disproportionately affected by ebbs and flows of species' geographical range.

Alleles↗

PubMed2000

Ocular Onchocerca infections in two dogs in western United States.

Two dogs, one from California and one from Arizona, were found to have aberrant infections caused by filarial nematodes of the genus Onchocerca. In both cases, the parasites are localized in or near the eye. In one case the worm was located in the cornea and was surgically removed. In the second case, a very marked granulomatous reaction was induced in the retrobulbar space, mimicking an abscess. This eye was enucleated. The worms in both instances were female, and were gravid, i.e. contained microfilariae in utero, indicating that a male worm(s) had been present and mating had occurred. The exact identity of the species of Onchocerca responsible cannot be determined, although the features observed are most like Onchocerca lienalis of cattle. These cases represent the fourth and fifth such cases reported from the US, and are especially interesting because of the unusual location of the worms, the small number of recognized cases, and the similarity to a recent zoonotic human infection.

Animals↗

PubMed1999

Intestinal parasites in patients with diarrhea and human immunodeficiency virus infection in Zimbabwe.

OBJECTIVES: To determine the prevalence of intestinal parasites and risk factors for infection associated with diarrhea in HIV-infected patients in Harare, Zimbabwe. DESIGN: Prospective observational study. METHODS: Single stool samples were collected from 88 HIV-infected individuals presenting with diarrhea of greater than 1 week duration. Stools were examined for intestinal parasites using modified acid fast stain, fluorescence- labeled monoclonal antibody for Cryptosporidium parvum, as well as a modified trichrome stain and a PCR-based protocol for Enterocytozoon bieneusi. RESULTS: C. parvum was detected in 9% (seven out of 82) of samples evaluated, but no Cyclospora was detected. E. bieneusi was detected in 18% (10 out of 55) of stool by trichrome staining and in 51% (28 out of 55) of stool examined by PCR. Risk factors for E. bieneusi infection were: living in rural areas, consumption of nonpiped water, contact with cow dung and household contact with an individual with diarrhea. CONCLUSION: E. bieneusi infection was common in HIV-infected patients with diarrhea in Zimbabwe and may be acquired through person-to-person and fecal-oral transmission.

AIDS-Related Opportunistic Infections↗

PubMed1997

Waterborne protozoan pathogens.

Protozoan parasites were the most frequently identified etiologic agents in waterborne disease outbreak from 1991 to 1994. The waterborne parasites Giardia lamblia, Naegleria fowleri, Acanthamoeba spp., Entamoeba histolytica, Cryptosporidium parvum, Cyclospora cayetanesis, Isospora belli, and the microsporidia are reviewed. For each parasite, the review includes history, life cycle, incidence, symptoms, and therapy. Clinical detection methods are compared, and emerging technologies are discussed. Information on the association of these parasites with waterborne outbreaks is reviewed. Current information on protozoan parasites identified as etiological agents in waterborne outbreaks is discussed. Water industry issues related to recent disease outbreaks are examined in the context of water quality testing regulations for G. lamblia and those proposed for C. parvum. The review identifies the limitations of the American Society of Testing and Materials water-testing method for these parasites. An overview of federal regulations affecting the water industry and laboratories that test for water quality is also provided. The article highlights the importance of the clinical laboratory as a frontline defense for the detection of infectious organisms. The review points to the need for clinical laboratories, physicians, and public health personnel to cooperatively plan and assess the challenge of meeting this potential public health threat.

Acanthamoeba↗

PubMed1994

Giardia lamblia trophozoites contain multiple alleles of a variant-specific surface protein gene with 105-base pair tandem repeats.

Giardia lamblia trophozoites undergo antigenic variation of a variant-specific surface protein (VSP). All VSPs that have been reported have had high cysteine contents, including numerous copies of a CXXC motif. The first vsp gene described (vspA6; from the cloned line, WBA6), contained 21 copies of a 195 base pair tandem repeat, but other reported VSPs have not contained repeats. In this report, we describe the vsp gene from WBC5, a cloned line derived from WBA6. The vspC5 gene contains short 5' and 3' regions flanking 26 copies of a 105-bp tandem repeat, which comprises 93% of the coding region. In addition to the copy containing 26 repeats, the genome contains other copies of the vspC5 with fewer copies of the repeat. The sequences flanking the repeats are identical, and all copies map to the same location on chromosomal Band 5, suggesting that multiple alleles of the vspC5 gene are present.

Alleles↗