Publisher Summary This chapter discusses interaction of helminths and their hosts within the alimentary canal and, especially the stomach and intestines. Many such parasites live in the gastro-intestinal canal while others penetrate into the wall of the canal and a few invade organs, such as the liver and pancreas. The dynamic relationship between parasite and host is clearly shown and a good example set for future researchers. First, there is a study of the parasite–host interface, including the various kinds of organs of attachment, the varied nature of the lumen and the mucosa of the gastrointestinal canal, the nature of adhesion, and absorptive surfaces of the helminth and the host. The chapter describes the ecology of helminth site selection by trematodes, cestodes, and nematodes and matters concerning concurrent infections, transplantation, and migration. The chemical and physical characteristics of the intestinal lumen ionic and osmotic characters, microbial ecology, enzymes, bile acids and dietary fats, nutritive gradients, and matters of luminal homeostasis are discussed. The functional gradients in the gastrointestinal tract, bearing on the absorption of electrolytes and nonelectrolytes, water absorption, and malabsorption are also discussed.

Ecological and Physiological Aspects of Helminth-Host Interactions in the Mammalian Gastrointestinal Canal

Frequency of attendance at religious services and cigarette smoking in American women and men: the Third National Health and Nutrition Examination Survey.

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 Clinically Significant Hemoflagellates

Trypanosoma cruzi: interaction with vertebrate cells in vitro. 1. Individual interactions at the cellular and subcellular levels.

Factors influencing the continuous recording of in situ pH of gastric and duodenal contents.

The cycle of Trypanosoma cruzi in tissue culture of embryonic heart muscle

The chemical nature of the cyst wall of human intestinal protozoa was studied on fresh material in human stools of cysts of Endamoeba histolytica, Endolimax nana, Councilmania lafleuri, and C. dissimilis, and Giardia lamblia.Notably in Councilmania lafleuri with reagents of high osmotic pressure such as 50% H2SO4 and concentrated lactic acid there is at first a caving in at the pore. Later there is a return to normal contour. In lactic acid the pore is thereafter evident. In 50% HNO3, 50% acetic acid, and 50% H2SO4, there is an early extension of the plug of the pore in the amoeba and in Giardia at the smaller end.Various authors have referred to the cyst wall as being probably chitin, pseudo-chitin(?), or cellulose. The following tests made by us for chitin were negative: Zander's1 iodine-zinc chloride test, Kuhnelt's2 sulfuric acid-iodine test, and the picro-nigrosine stain. The amyloid test for cellulose was also negative.Untreated cyst walls give a violet color reaction with Mayer's muchaematin stain....

Chemical Nature of the Cyst Wall in Human Intestinal Protozoa.

Electrometric pH determinations of the walls and contents of the gastro-intestinal tracts of normal albino rats

Correlation of the Distribution of the Protozoa in the Intestine of Rattus norvegicus with the Hydrogen Ion Concentration of the Intestinal Contents and Wall.

Ethel McNeil

Papers

The cycle of Trypanosoma cruzi in tissue culture of embryonic heart muscle

Chemical Nature of the Cyst Wall in Human Intestinal Protozoa.

Electrometric pH determinations of the walls and contents of the gastro-intestinal tracts of normal albino rats

Correlation of the Distribution of the Protozoa in the Intestine of Rattus norvegicus with the Hydrogen Ion Concentration of the Intestinal Contents and Wall.

Effects of arsenicals on trypanosoma cruzi in tissue culture