PubMed Health⌕ Search

Biomedical subjects

D Heyneman

Publications and source records attributed to D Heyneman.

At least 19 recordsLinked to original sources
PubMed1986

Schistosomiasis in an American medical investigator.

A 42-year-old American male researcher contracted schistosomiasis from environmental sources in the course of his observations on human behavior in Upper Egypt. After a long asymptomatic period, he developed various symptoms and Schistosoma haematobium was found in a urine examination. After treatment with Metrifonate, urine examination became negative. However, abdominal pain persisted and most diagnostic tests were negative. Colonoscopic examination and biopsy of the mucosa revealed schistosomiasis. Treatment with Praziquantel was thoroughly effective in clearing the persistent Schistosoma haematobium infection. It is necessary to maintain a high index of suspicion in cases of potential schistosomiasis. The availability of nontoxic treatment is discussed.

Adult↗
PubMed1984

Use of the enzyme-linked immunosorbent assay (ELISA) for detection of Entamoeba histolytica antigen in faecal samples.

A promising new ELISA method developed by Root et al. to diagnose amoebiasis by the detection of Entamoeba histolytica coproantigen was tested in Mexico City and was reported to be more than twice as sensitive as microscopy. In this study the same procedure was compared to microscopy for paired specimens from 107 patients in San Francisco. Microscopy was more than twice as sensitive as ELISA: of 12 specimens positive by microscopy only 5 were also positive by ELISA. The ELISA did not detect a single specimen not detected by microscopy. Over-all, there was a 93% agreement between the two tests: 5% were positive and 89% negative by both tests. Possible reasons for the differences in the San Francisco and Mexican City findings are discussed.

Antigens, Protozoan↗
PubMed1983

The ultrastructure of the amebocyte-producing organ in Biomphalaria glabrata.

The amebocyte-producing organ (APO) in normal and echinostome-sensitized Biomphalaria glabrata was studied at the ultrastructural level. The APO in unexposed snails consists of small clusters of primary ameboblasts resting on the epithelial cells lining the pericardium. The ameboblasts are held in a loose reticulum formed by extensions from smooth muscle and few fibroblastic cells. Secondary ameboblasts and amebocytes constitute further stages of this cell line. Amebocytes, resembling cells in the snail's circulation, appear in the blood sinus coursing through the interior of the APO. Exposure of snails to echinostome miracidia results in significant morphological changes in the organ. Large clusters of primary and and secondary ameboblasts appear, many of these cells undergoing mitosis. Fully activated APOs consist of masses of cells loosely arranged in zones of progressive maturation. Blood cells in activated APOs were significantly larger than those seen in normal APOs.

Animal Population Groups↗
PubMed1982

Further characterization of acquired resistance in Biomphalaria glabrata.

The albino strain of Biomphalaria glabrata is capable of developing an acquired resistance to echinostomes that is relatively specific, i.e., strong against Echinostoma lindoense, challenged by the homologous species, moderate or weak against closely related E. paraensei and E. liei, and nonexistent against Paryphostomum segregatum and Schistosoma mansoni. The present results show that acquired resistance induced by E. paraensei is much stronger against the heterologous E. lindoense than against the homologous species. These observations indicate that although the response of snails with acquired resistance to a challenge exposure is relatively specific, the stimuli for inducing that resistance may be nonspecific.

Animals↗
PubMed1981

Selective interference with granulocyte function induced by Echinostoma paraensei (Trematoda) larvae in Biomphalaria glabrata (Mollusca).

Various trematode larvae can interfere with the host snail's resistance to the same or unrelated trematode species, chiefly, it appears by interference with the function of the host's granulocytes. In Biomphalaria glabrata infected with the trematodes, Echinostoma paraensei, granulocytes lose their ability to encapsulate the larvae of trematodes to which the hosts were previously resistant. However, the granulocytes in these snails retain their ability to encapsulate injected latex spheres, or larvae of the metastrongyle nematode, Angiostrongylus malaysiensis, and to phagocytose epidermal plates cast off by miracidia of the trematode, Schistosoma mansoni. Cellular infiltration in injured preputial tissue of the snail also was not suppressed by the presence of E. paraensei larvae. Interference with the granulocyte function in B. glabrata induced by E. paraensei infection therefore appears to be a selective phenomenon.

Angiostrongylus↗
PubMed1980

Tissue reactions induced by Schistosoma mansoni in Biomphalaria glabrata.

In Biomphalaria glabrata with a strong natural resistance, Schistosoma mansoni sporocysts are rapidly encapsulated by granulocytes and killed, mainly by the strong phagocytic activity of the cells. Irradiated Echinostoma paraensei sporocysts seem able to suppress the function of the granulocytes. Tissue reactions in snails with self-cure demonstrate: involvement of two types of cells, granulocytes and hyalinocyte-like cells; formation of amoeba-fibrous capsules; limited tendency of granulocytes to become attracted to the parasites; a slow process of parasite destruction; and a possible involvement of humoral factors. It seems that there is partial suppression of the granulocyte function in smails with self-cure.

Animals↗