Parasitic cysts

Yan, Y., Smant, G., Stokkermans, J., Qin, L., Helder, J., Baum, T., Schots, A. and Davis, E. (1998) Genomic organization of four 5-1,4-endoglucanase genes in plant-parasitic cyst nematodes and its evolutionary implications. Gene 220, 61-70. 

Mucoepidermoid carcinoma was first described by L.E. PiANzoLA et al. in 1971. (222) It is a rare entity this sub-type constitutes only 2-3% of all CCC. Up to now, 41 cases have been reported. The tumour contains components of both adenocarcinoma and squamous cell carcinoma. It is discussed that this condition derives from a squamous metaplasia of the terminal ramifications of the bile canaliculi (222) or from adenocarcinoma cells. A combination of HCC and mucoepidermoid carcinoma has been observed. (219) This tumour contains components of both cell types. A male predominance was found. The clinical findings and laboratory data are similar to CCC. Pathogenesis is unknown various congenital cysts of the biliary tract (218) and non-parasitic cysts (221, 223) as well as hepatic cholelithiasis (usually associated with infection) have been proposed as aetio-logical factors. (217) Although its resectability was... 

Yagi, H., Ueda, M., Kawachi, S., Tanabe, M., Alura, K., WakabayasM, G., Shlmazn, ]>X, Sakamoto, M., Kltajima, M. Squamous cell carcinoma of the liver originating from non-parasitic cysts after a 15 year follow-up (case report). Eur. J. Gastroenterol. Hepatol. 2004 16 1051-1056... 

Ozone has been found to be very effective on inactivating a wide range of microorganisms. It is generally accepted that molecular ozone is a more effective biocide than hydroxyl radicals, because the latter are very short-lived and nonselective. The resistance of microorganisms follows the increasing order bacteria, viruses, and parasite cysts. 

Human alveolar echinococcosis is endemic in the eastern part of France, in Switzerland, Russia, Japan, Canada and Alaska. Cell-mediated immunity may be responsible for a granulomatous proliferation with epithehoid cells, giant cells and numerous lymphocytes surrounding parasitic cysts. 

Microfiltration (MF), like ultrafiltration, is a pressure-driven membrane process. In the case of microfiltration, the pore size is typically in the 0.03- to O.l-pm range. In this range, individual bacteria and viruses will pass through the membrane. However, colloidal suspended sohds, floe particles, and parasite cysts are prevented from passing. No removal of dissolved solids is accomplished by microfiltration membranes. 

Pneumocystis pneumonia occurs in patients with congenital or acquired immunodeficiency, for instance transplant patients and others who are receiving immunosuppressive therapy. Not infrequently, Pneumocystis pneumonia coexists with other pulmonary infections. The infection may be diffuse or focal, with a propensity to affect the lower lobes. In contrast with several other forms of pneumonia, there is no fibrinous pleurisy. The alveolar septa are increased in thickness and infiltrated with plasma cells and lymphocytes. The characteristic feature is the intra-alveolar exudate. This is foamy and strongly periodic acid-Schiff (PAS) positive, being composed of parasitic cysts. An intra-alveolar eellular reaction to the exudate is absent, and a few areas of hyaline membrane formation may be found. The diagnosis may be obtained by lung biopsy material. The organism may also be seen in sputum. In some instances, diffuse interstitial fibrosis may be the end result. 

Balantidiasis (balantidiosis, balantidial dysentery), an intestinal disease seen almost worldwide, is caused by the large ciUated protozoan, balantidium coll The organism is usually found in the lumen of the large intestine of humans and animals. Cysts formed in the lumen of the colon or in freshly evacuated feces of humans or domesticated and wild animals, can colonize the colon and terminal ileum of new hosts by the latter s ingestion of contaminated food or water. The hog has been found to be the most heavily parasitized host. Its association with the rat may be a means for maintaining a reservoir infection in the two animals. 

Entamoeba histolytica is an anaerobic rhizopod that occurs in tropical and subtropical areas. It can cause intestinal and extraintestinal manifestations. It is transmitted orally by ingestion of cysts that develop into trophozoites in the large intestine. Amebic trophozoites release several cytolytic factors, e.g. amoe-bapore, which enable the parasite to invade tissue. In intestinal amoebiasis, E. histolyticatrophozoites invade the intestinal mucosa, causing a form of ulcerative colitis with bloody and mucous diarrhoea. Extraintestinal manifestation of amebiasis results in abscess formation, usually in the liver but sometimes in the brain. 

B. R. Kerry and D. M. Crump, Two fungi parasitic on females of cyst nematodes Heterodera spp.). Transactions of the British Mycological Society 74 119 (1980). 

B. R. Kerry, D. H. Crump, and C. A. Mullen, Studies of the cereal cyst nematode Heterodera avenae, under continuous cereals, 1975-1978 II. Fungal parasitism of nematode females and eggs. Annals of Applied Biology /00 489 (1982). 

Fresh stool may show trophozoites while preserved specimens yield cysts. (Note stool for ova may show the presence of other parasites [e.g., Cryptosporidium parvum, E. histolytica, or E. hartmanni] multiple stool samples may be needed.)... 

Parasites of humans proliferate tremendously at certain stages, with thousands or even millions of forms being produced for every one that survives to perpetuate the parasite. Parasites may be quite hardy. For example, certain stages, particularly eggs and cysts, may survive for weeks or months in the environment. 

Identification may be by gross examination for adult helminths or, more commonly, by microscopic examination for protozoa, helminth eggs, and larvae. The diagnostic forms of some parasites, such as the eggs of Ascaris spp., are present on a regular basis. Other forms, such as malaria parasites, Taenia eggs, or Giardia cysts, vary from day to day. 

The direct wet mount made from unconcentrated fresh feces is most useful for the detection of the motile trophozoites of intestinal protozoa and the motile larvae of Strongyloides spp. It is also useful for the detection of protozoan cysts and helminth eggs. For fixed feces, the direct wet mount may allow the detection of parasites which do not concentrate well. This method is also useful for the examination of specific portions of feces, such as flecks of blood or mucus. 

In an ideal stain, the cytoplasm of cysts and trophozoites is blue-green tinged with purple. Entamoeba coli cyst cytoplasm is often more purple than that of other species. Nuclear chromatin, chromatoid bodies, erythrocytes, and bacteria stain red or purplish red. Other ingested particles such as yeasts often stain green. Parasite eggs and larvae usually stain red. Inflammatory cells and tissue cells stain in a fashion similar to that of protozoa. Color reactions may vary from the above. 

Fluids such as tissue aspirates, cyst fluid, bronchial washings, cerebrospinal fluid, pleural fluid, and peritoneal fluid can be examined directly, or they can be centrifuged and the sediment examined by wet mounts or stains (or both), depending on the parasite suspected, as described above for abscesses or tissue. 

Nematode-host interactions are complex and poorly understood. The relationship between cyst nematodes and their hosts appears to have co-evolved, and as a result there are numerous genes for host resistance that are complemented by nematode parasitism genes (Triantaphyllou, 1987). Different alleles of these genes may interact in various combinations to give... 

The interaction of soybean cyst nematode (SCN) with soybean (Glycine max) has been extensively studied in the United States. This system has been used as a model to dissect the genetics of nematode parasitism, mainly due to the tractability of classical genetic manipulation of the nematode. The remainder of this brief review will focus on the SCN side of the interaction with its host and the progress that has been made in unravelling the complex genetic systems controlling parasitic behaviour. 

Dong, K. and Opperman, C.H. (1997) Genetic analysis of parasitism in the soybean cyst nematode Heterodera glycines. Genetics 146, 1311-1318. 

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