Publications by authors named "Jacob K Frenkel"

5 Publications

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Ultrastructural aspects of Cystoisospora belli (syn. Isospora belli) in continuous cell lines.

Microsc Res Tech 2014 Jun 28;77(6):472-8. Epub 2014 Apr 28.

Technics School of Health, Federal University of the Uberlândia, Umuarama, CEP 38400-902, Uberlândia, Minas Gerais, Brazil.

Cystoisospora belli is an opportunistic protozoan that causes human cystoisosporiasis, an infection characterized by diarrhea, steatorrhea, abdominal pain, fever, and weight loss. The lack of animal models susceptible to C. belli, and the difficulty in obtaining clinical samples with fair amounts of oocysts have limited the research pertaining to the basic biology of this parasite. This study aimed to describe the ultrastructure of endogenous stages of C. belli in Monkey Rhesus Kidney Cells (MK2) and Human Ileocecal Adenocarcinoma cells (HCT-8). Zoites of C. belli exhibited typical morphological features of coccidia, which included a trilaminar pellicle, an apical complex formed by a conoid, polar rings, rhoptries, and micronemes, in addition to dense granules and the endoplasmic reticulum. No crystalloid body was observed but various lipid and amylopectin granules were usually present in the cytoplasm of zoites. We observed a tendency of the endoplasmic reticulum of the host cell to be located near the parasitophorous vacuole membrane. Merozoites were formed by endodyogeny and during replication, the apical complex of the mother cell remained intact. The formation of gametes or oocysts was not observed. The ultrastructural findings of C. belli are further evidence of its proximity to Sarcocystidae family members and corroborate their reclassification as Cystoisospora spp.
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http://dx.doi.org/10.1002/jemt.22372DOI Listing
June 2014

Pneumocystis and Trypanosoma cruzi: nomenclature and typifications.

J Eukaryot Microbiol 2006 Jan-Feb;53(1):2-11

National Program on Environmental Health-Biodiversity, Agriculture and Agri-Food Canada, Central Experimental Farm, KW Neatby Building, 960 Carling Avenue, Ottawa, Ontario K1A 0C6, Canada.

Published phylogenetic reclassifications of Pneumocystis as a fungus resulted in a nomenclatural shift from the Zoological Code to the International Code of Botanical Nomenclature. The same may be true for all microsporidians and sundry other organisms. This resulted in the invalidation of names and subsequently precipitated changes to the botanical code to accommodate Pneumocystis and microsporidian names. The repercussions following application of the 2005 Vienna Code to Pneumocystis nomenclature are detailed. Validity of the name for the human pathogen, Pneumocystis jirovecii, is re-established from its 1976 publication under the Zoological Code, contrary to interpretation of validity under earlier botanical codes. Pneumocystis jirovecii is lectotypified and epitypified. The rat parasite, Pneumocystis carinii, is neotypified, separating it from Pneumocystis wakefieldiae. The original 1909 description of Trypanosoma cruzi, type species for Schizotrypanum, and causal agent of Chagas' disease, included parts of the life cycle of Pneumocystis. Trypanosoma cruzi is neotypified by the true Trypanosoma elements, thereby completing the nomenclatural separation from Pneumocystis and ensuring that Schizotrypanum is not applicable to Pneumocystis as an earlier name. The neotypes for P. carinii and T. cruzi represent the strains currently being investigated by their two respective genome projects. They were selected in light of their medical importance, physiological characterizations, and absence of lectotypifiable materials. The classification and nomenclature of Pneumocystis is reviewed and guidelines given for the publication of new species.
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http://dx.doi.org/10.1111/j.1550-7408.2005.00072.xDOI Listing
May 2006

The roles of cats and dogs in the transmission of Toxoplasma infection in Kuna and Embera children in eastern Panama.

Rev Panam Salud Publica 2004 Sep;16(3):176-86

Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana 70112, USA.

Objective: To examine the relationship between antibody status and various hypothesized risk factors for Toxoplasma gondii infection among two different Amerindian populations in eastern Panama. Following up on earlier research that we conducted, we now explore the role of dogs in the natural transmission of Toxoplasma, the role that dogs play in promoting transmission, the interactive effect of cats and dogs, and the accessibility of infective material to children.

Methods: In 1991, 10 Panamanian medical students conducted interviews and took blood samples from 760 Kuna and Embera children aged 2 through 12 years in the Upper Bayano River Basin and the San Blas Islands. Serologic assays were performed using direct agglutination. The data analyses in the 1990s included univariate, bivariate, and multivariate analyses, without regard to data on dogs. Further bivariate and multivariate analyses were performed in 2003 to examine the contribution of dogs.

Results: In communities with high Toxoplasma antibody prevalence in children, logistic regression suggested that the factors predictive of antibody presence were: compacted soil floors of huts (P = 0.001), having a dog (P = 0.038), and the interviewer seeing a cat in the house (P = 0.049). Our results suggest that the villagers' dogs play a significant role in facilitating the transmission of Toxoplasma gondii to humans, most often in the presence of cats in the houses, and only in those communities with higher Toxoplasma seroprevalence in children.

Conclusions: Dogs may act as mechanical vectors, by rolling in foul-smelling substances and by ingesting fecal material. In areas of high Toxoplasma prevalence in children and where dogs and cats are plentiful, immunocompromised individuals and pregnant women should be warned of the possibility of acquiring Toxoplasma gondii from dogs as well as from soil contaminated by cats. People should be encouraged to wash their hands after contact with soil, dogs, or cats as well as before eating.
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http://dx.doi.org/10.1590/s1020-49892004000900004DOI Listing
September 2004

Isospora belli infection: observation of unicellular cysts in mesenteric lymphoid tissues of a Brazilian patient with AIDS and animal inoculation.

J Eukaryot Microbiol 2003 ;50 Suppl:682-4

Department of Biology, Univ of New Mexico, Albuquerque, NM, USA.

We describe the finding of unizoic cysts of Isospora belli in lymphoid tissues of a Brazilian patient with AIDS, and discuss the possibilities of their drug resistance, they being the cause of relapses, and of being an indication for the existence of intermediary or paratenic animal hosts.
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http://dx.doi.org/10.1111/j.1550-7408.2003.tb00686.xDOI Listing
March 2004

[Extraintestinal finding of Isospora belli unizoic cysts in a patient with AIDS: case report].

Rev Soc Bras Med Trop 2003 May-Jun;36(3):409-12. Epub 2003 Jul 31.

University of New Mexico, Albuquerque, NM 87501, USA.

This report describes the presence of Isospora belli unizoic cysts in mesenteric lymph nodes and of gametocytes in the gallbladder epitelium of a 26 year-old Brazilian male patient with Acquired Immune Deficiency Syndrome. This patient had received treatment for several times with sulfamethoxazole-trimethoprim. It is discussed the significance of I. belli tissue cysts as possible foci of resistance of the parasite and their association with the infection relapse even post-treatment with anticoccidian medication.
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http://dx.doi.org/10.1590/s0037-86822003000300014DOI Listing
October 2003