F. D. Wood

Bio: F. D. Wood is an academic researcher. The author has contributed to research in topics: Trypanosoma cruzi & Embryonic heart. The author has an hindex of 1, co-authored 1 publications receiving 27 citations.

Cultivation of Clinically Significant Hemoflagellates

Abstract: The hemoflagellates, Trypanosoma spp. and Leishmania spp., are causal agents of a number of parasitic diseases having a major impact on humans and domestic animals over vast areas of the globe. Among the diseases are some of the most pernicious and deadly of human afflictions: African sleeping sickness, Chagas' disease, kala-azar, and Oriental sore. The organisms have complex, pleomorphic life cycles typically involving a vertebrate and an invertebrate host, the latter serving as a vector. In the vertebrate host, they are primarily blood and tissue parasites. In their transition from one host to another, the hemoflagellates undergo morphological, physiological, and biochemical changes that facilitate their growth and subsequent transmission. A major goal in the study of the hemoflagellates has been the cultivation in vitro of both vertebrate and invertebrate stages of the organisms. The first types of media used in their cultivation, and still useful for establishment of cultures, were undefined and contained a complex of ingredients. These gave way to semidefined formulations which included tissue culture media as a base and, as a next step, addition of tissue culture cells as a feeder layer to promote parasite growth. More recently developed media are completely defined, having replaced the feeder cells with various supplements. Serum, a sometimes-variable component of the media, can be replaced by various serum substitutes. This review focuses on the hemoflagellates that infect humans, describing stages in the development of media leading to the fully defined formulations that are now available for the cultivation of many of these organisms.

Cultivation of Trypanosoma cruzi in irradiated muscle cells: improved synchronization and enhanced trypomastigote production

Abstract: Since the in vitro production of trypomastigote stages of Trypanosoma cruzi in cell culture is frequently limited by (1) host cell overgrowth and (2) by the unequal redistribution of parasites after cell division resulting in asynchronous release of trypomastigotes, a culture system was devised in which host cell mitosis was inhibited by irradiation prior to parasite infection. L-6 rat myoblast cells when exposed to 3000 rad. of gamma radiation lost their ability to divide but remained susceptible to infection with, and capable of supporting the intracellular growth of, T. cruzi. Using this approach it proved possible to have virtually 100% of cells infected and achieve much better synchronization of trypomastigote release than with conventional culture systems. Additionally, the total number of parasites provided approached 1 x 10(9) trypomastigotes/150 cm2 flask, a significant increase over other culture systems. Preliminary studies with Plasmodium fallax an Eimeria tenella indicate that irradiated host cells may be utilized to advantage for the cultivation of other intracellular protozoa.

The morphology and life cycles of trypanosomes.

Abstract: INTRODUCTION A recent examination ofculture forms of Trypanosoma cruzi in my own laboratory disclosed a growing mass of actively motile flagellates the majority of which were without undulating membranes. This situation appeared to be contrary to most published reports, which state that motile forms in the invertebrate host and in culture are predominantly crithidiform (Fig. 6B), characterized by a kinetoplast located in front of the nucleus and an anterior, short undulating membrane. In our cultures a large number of metacycic stages (see p. 9), characterized by a kinetoplast located at the posterior end of the body and by a long undulating membrane and short anterior flagellum, were always present, but mature crithidials were uncommon. It occurred to me that these metacyclic flagellates were probably derived from cells other than crithidials, and since the usual description of trypanosome life cycles states that metacyclic stages come from crithidials, a study of the evidence for the statement seemed desirable, and led to an expansion of the present article to include a review of the literature on the morphology and life histories of trypanosomes. In 1936 Hoare (1936a) published an excellent outline of the classification of mammalian trypanosomes. This study was based on some earlier work of Hoare and Coutelen (1933). Part of Hoare's system of classification includes a consideration of life cycles. It is appropriate, therefore, to use this classification as a basis for the present review. Trypanosoma zapi, described in detail in 1952 by Davis, has been added to Hoare's list of examples. An early comprehensive review of the work on trypanosomes and trypanosomiasis is that of Laveran and Mesnil (1912), who discussed the classification and life cycles, but gave little consideration to the evolution of trypanosomes. The evolution of the group is discussed by Hoare and Coutelen (1933), by Hoare (1936), and by Grass6 (1952). The following abbreviated description of trypanosomes in vertebrate hosts is modified from the original according to suggestions made by Dr. Hoare (1954) in a personal communication.