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Biomedical subjects

B Fried

Publications and source records attributed to B Fried.

At least 145 records · Page 8Linked to original sources
PubMed1990

Excystation of five digenean metacercariae in vitro and in the peritoneal cavity of the mouse.

Excystation of metacercariae of Parorchis acanthus, Posthodiplostomum nanum, Posthodiplostomum sp., Posthodiplostomoides leonensis and Clinostomum tilapiae in mammalian saline at 39 degrees C was similar to their excystation in mouse peritoneal cavity. Extrinsic enzymes were not needed for C. tilapiae excystation but were an absolute necessity for P. acanthus excystation. Extrinsic pepsin enhanced P. nanum excystation but was not obligatory. Acid pepsin was an absolute requirement for Posthodiplostomum sp. and Posthodiplostomoides leonensis excystation. It was noted that acid saline could not be substituted for acid pepsin and that there was diversity in the condition involved in digenean excystation.

Animals↗
PubMed1990

Single- and five-worm infections of Echinostoma caproni (Trematoda) in the ICR mouse.

Twenty-nine (64%) of 44 ICR mice fed a single metacercarial cyst of Echinostoma caproni and all of 23 mice each fed five cysts were infected with ovigerous worms at necropsy 2-4 weeks post-infection. Each host fed five cysts had two to five worms at necropsy, and all worms were either paired or clustered. Distribution of worms in the small intestine was similar in single- and five-worm infections and all worms were located 17-20 cm anterior to the ileo-cecal valve. Both single and multiple worms produced eggs with fully-developed miracidia. The number of eggs per uterus in 2-week-old multiple worms was almost twice that of single worms. The body area of 3- and 4-week-old multiple worms was significantly greater than that of single worms of the same age.

Animals↗
PubMed1990

Sterols in the plasma and digestive gland-gonad complex of Biomphalaria glabrata snails, fed lettuce versus hen's egg yolk, as determined by GLC.

1. Gas-liquid chromatography studies were done on sterols in plasma and the digestive gland-gonad (DGG) complex of Biomphalaria glabrata snails fed lettuce vs hen's egg yolk. 2. The major sterols present in the DGG of both populations were cholesterol, stigmasterol, beta-sitosterol, campesterol, and desmosterol. 3. The percentage composition of cholesterol in the DGG of yolk vs lettuce fed snails was 82 and 51, respectively. 4. The elution profiles of sterols in the plasma of yolk vs lettuce fed snails were similar; both contained desmosterol, campesterol, and stigmasterol, negligible amounts of cholesterol, and unidentified sterols. 5. The high lipid diet increased the level of cholesterol in the DGG but not in the plasma.

Animals↗
PubMed1990

Single and multiple worm infections of Echinostoma caproni (Trematoda) in the golden hamster.

Six of 10 hamsters fed a single metacercarial cyst of Echinostoma caproni (single-worm infections) and 13 of 19 hamsters fed either 2 or 5 cysts (multiple-worm infections) were infected with adult echinostomes at necropsy 22 days post-infection. Considerable histopathological changes to the small intestine occurred in hamsters carrying single-worm infections. There were no differences in either mean length, width or wet weight of echinostomes in single- versus multiple-worm infections. The mean number of eggs/worm from single-worm infections (525) was significantly greater than that from multiple-worm infections (288). The average percentage of fully developed miracidia/worm from single worms (94%) was similar to that from worms in multiple infections (92-95%). Single worms of E. caproni were capable of self-fertilization and production of viable eggs. Miracidia derived from single worms were as capable of infecting laboratory-reared Biomphalaria glabrata and producing patent rediae as were those from multiple infections.

Animals↗
PubMed1990

Taxonomy of 37-collar spined Echinostoma (Trematoda: Echinostomatidae) in studies on the population regulation in experimental rodent hosts.

With reference to a recent taxonomic revision the species of the echinostomes used in key studies on the population regulation in infections with 37-collar-spined Echinostoma species in experimental rodent hosts were reconsidered. This was considered essential to prevent taxonomic problems blocking further fruitful progress within this field of experimental parasitology.

Animals↗
PubMed1990

Mallard ducklings (Anas platyrhynchos) experimentally infected with Echinostoma trivolvis (Digenea).

Of 8, day-old mallard ducklings, each fed 50 encysted metacercariae of Echinostoma trivolvis, 4 (50%) were infected 15-31 days postinfection (PI) with a total of 10 (2.5%) worms. The worms were attached loosely to the mucosa of the lower ileum and rectum-cloaca, and some were ovigerous by day 15 PI. Ducklings, 4-14 days old when fed encysted metacercariae, became infected with E. trivolvis adults, but ducks 150 days old were refractory to infection. Compared to our previous studies on experimental infections of echinostomes, mallard ducklings were less susceptible than golden hamsters to E. trivolvis.

Animals↗
PubMed1989

Schistosoma mansoni: female-dependent lipid secretion in males and corresponding changes in lipase activity.

Eight to 10-week old Schistosoma mansoni males from unisexual infections were examined histochemically for neutral lipids and lipase activity. In addition, in situ fixed pairs were examined for lipase activity. Neutral lipid content of males from unisexual infections was variable and lipase activity was minimal. Following 1 h incubation at 37 degrees C in Earle's balanced salt solution (EBSS) in which females had previously been maintained for 1 h, males showed moderate increase in lipid content and diminished lipase activity. In contrast, unisexually developed males incubated for 1 h with females from bisexual infections showed increased lipid accumulation and lipase activity. Unisexually developed males incubated for 1 h in EBSS showed both lipid accumulation and release from the dorsal surface. Worm-pairs fixed in situ showed greater lipase activity in females than in males. These observations suggest that a factor(s) released by females affects the physiology of males.

Animals↗
PubMed1989

Infectivity, growth, development and pathology of Echinostoma caproni (Trematoda) in the golden hamster.

Laboratory hamsters (Mesocricetus auratus) were experimentally infected with 75 +/- 15 metacercarial cysts of Echinostoma caproni. Worms were recovered from days 7 to 89 post-infection with eight to 90 (average 37) parasites in the small intestine. Worm wet weights averaged 0.85 mg at 10 days, 1.8 mg at 17 days, 3.4 mg at 45 days, and 7.7 mg at 89 days; average dry weights for the identical days were, 0.15, 0.30, 0.70 and 2.2 mg, respectively. The average body area of worms fixed in hot (80 degrees C) alcohol-formalin-acetic acid was 0.21 mm2 on day 3, 4.9 mm2 on day 10, and 17.7 mm2 on day 42. Clinical signs in some hamsters included progressive unthriftiness and watery diarrhea. Gross examination revealed enlarged lymphatic nodules along the length of the small intestine. The histopathological responses of hamsters to the parasite showed erosion of the intestinal villi with lymphocytic infiltration being the primary response; hemorrhagic areas were also observed in the villi.

Animals↗
PubMed1989

Cultivation of trematodes in chick embryos.

The chick embryo can be used as a substitute for adult animals in the cultivation of a variety of parasites. Bernard Fried describes its use in cultivating trematodes, and suggests that the system might be useful as a preliminary chemotherapeutic screen.

Journal Article↗
PubMed1989

Esterases in natural populations of normal and Echinostoma revolutum-infected Helisoma trivolvis (Gastropoda).

Esterases of the digestive gland-gonad (DGG) complex of individual snails from a wild population of Helisoma trivolvis infected with the trematode Echinostoma revolutum were analyzed by vertical slab PAGE and compared to similar DGG homogenates of uninfected conspecifics from the same population. Our analysis indicated that: 1. Four classes of esterases, some atypical, could be resolved using diagnostic inhibitors. 2. Uninfected snails demonstrated polymorphism for two of these four esterase groups, including cholinesterases (CHE), in the 34 individual DGGs analyzed. 3. The rarer of the two ChE phenotypes in the uninfected sample (29.4%) was present in 100% of the 17 infected snails examined. However, no changes in esterase zymograms of infected DGGs due to the parasite were noted. 4. The possibility that the 'rare' ChE phenotype is somehow related to host susceptibility to Echinostoma revolutum is discussed in view of similar apparent linkages in other snail-trematode systems.

Animals↗
PubMed1989

Pathological effects of Echinostoma caproni (Trematoda) in the domestic chick.

Domestic chicks experimentally infected with Echinostoma caproni for 2 weeks showed a dilated ileum, unkempt feathers, watery diarrhoea, and weight loss. The ileum from infected and control chicks was fixed in 10% neutral buffered formalin, and prepared as 10 microns paraffin sections stained in haematoxylin and eosin, Papanicolau, periodic acid-Schiff, picro-ponceau, and alcian blue. The infected ileum showed atrophic villi, hypertrophied circular musculature with collagen-like fibres and haemorrhagic zones. The brush borders of epithelial cells and goblet cells were absent in the mucosa of the infected ileum. Worms in contact with host mucosa showed tissue plugs in the suckers. The cephalic spines of worms abraded the host mucosa.

Animals↗
PubMed1989

Decentralized hospital management: rationale, potential, and two case examples.

Sunnybrook Medical Centre (SMC) in Toronto designed a unique organizational model for managing hospital services and programs in three clinical units. The SMC model, like a similar model at The Johns Hopkins Hospital (JHH), emphasizes the active participation of physicians in management, the decentralization of budgetary control, and accountability for resource use to the clinical unit level. Expanding on the JHH model, SMC implemented additional financial incentives to encourage changes in clinical practice which would bring direct financial benefit to the respective clinical unit, and thereby to the medical center. To improve quality of service, SMC has also expanded the JHH model of multidisciplinary and participatory approaches to patient care by standardizing managerial roles and responsibilities of each member of the management team. A brief description of issues related to implementation of these unique models summarizes the program's success.

Baltimore↗
PubMed1989

Joint case writing: maintaining the validity and relevance of training in health care administration.

The Canadian College of Health Service Executives, the personal membership professional association for senior health care managers in Canada, has developed a unique approach to enriching the quality and increasing the productivity of the academic-field relationship. This paper describes the development of the program, the need for linkages between faculty, and the field and the limitations of the case method as traditionally practiced.

Canada↗