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S Walbaum

Publications and source records attributed to S Walbaum.

At least 19 recordsLinked to original sources
PubMed1997

Histochemical observations of alkaline phosphatase activity of Echinococcus multilocularis during in vivo development in golden hamsters, an alternative definitive host.

Histochemical observations of alkaline phosphatase activity of Echinococcus multilocularis during the in vivo development in golden hamster, an alternative definitive host. The present work reports on the ability of protoscoleces from a European fox strain of E. multilocularis to differentiate and develop into the adult form in the small intestine of male golden hamsters treated with prednisolone. Detection of alkaline phosphatase activity on various stages of the developing worm was performed by histochemical methods. The enzyme activity was not demonstrable in the early stages of infection but occurred with strobilization. Age-related changes in the distribution of the enzyme activity took place during strobilization. Alkaline phosphatase activity was evident in the excretory ducts of 8 to 11 day old strobila and in the tegument of mature proglottis of 16 day old worms. This in vivo procedure with rodents as definitive hosts provides interesting preliminary results on the biology of the E. multilocularis adult. Further investigations on membrane-bound enzymes involved in physiological and nutritional processes are in progress.

Alkaline Phosphatase↗
PubMed1997

Increases in the effects of albendazole on Echinococcus multilocularis metacestodes by the dipeptide methyl ester (Phe-Phe-OMe).

Three months after infection with Echinococcus multilocularis, Mongolian gerbils were given either the dipeptide methyl ester (Phe-Phe-OMe) or a combination of Phe-Phe-OMe plus albendazole to treat alveolar echinococcosis. Each drug was given orally at the daily dose of 50 mg/kg of body weight following various administration regimens. Histologic and ultrastructural studies of parasites recovered from infected gerbil tissues showed that the dipeptide methyl ester increases the effect of albendazole.

Albendazole↗
PubMed1995

Effects of Isoprinosine on Echinococcus multilocularis and E. granulosus metacestodes.

An in vivo study of the effect of Isoprinosine on Echinococcus multilocularis and E. granulosus metacestodes (Cestoda) was performed. Short- and long-term treatments with different doses were tested in experimental hosts: jirds for E. multilocularis and mice for E. granulosus. Modifications in the weight of animals as well as macroscopical and ultrastructural aspects were registered for each animal group. The results obtained showed a considerable ultrastructural alteration in E. multilocularis metacestodes after short-term treatment with the highest dose, and the tissue transplants were negative. In E. granulosus cysts the ultrastructural damage was also very important and its severity increased as the dose was raised. For the two parasites, the macroscopical aspect and weight of the lesions were profoundly changed.

Abdominal Muscles↗
PubMed1995

Echinococcus multilocularis protoscoleces and hepatic cell activity in vitro.

E. multilocularis protoscoleces were co-cultured with hepatic cells in the presence of IAR 20 or BALB/c 3T3 cells. Hepatocyte activity was determined by assaying transferrin and albumin secretion in culture media. The level of these 2 plasma proteins is higher in hepatic/BALB/c 3T3 co-culture medium. In the presence of parasites, the transferrin level is unchanged while the production of albumin is stimulated during the first 48 h. Our results suggest that the albumin production could be attributed to a complex cellular cooperation between hepatocytes and activated Kupffer cells as previously observed in the acute inflammatory reaction.

3T3 Cells↗
PubMed1994

Echinococcus multilocularis: in vitro interactions between protoscolices and Kupffer cells.

Echinococcus multilocularis protoscolices collected from experimentally infected jirds were incubated for 2 weeks in rat hepatic cell cultures cocultivated with or without feeder cells (BALB/c 3T3 and IAR 20). Scanning and transmission electron microscopy studies were performed during the course of the culture period. Kupffer cells (Kc) were seen adhering to the anterior and posterior ends of the protoscolices. Some protoscolices were fixed to the cell monolayer by a cluster of Kc adhering to the posterior end of the parasite. These cells were phagocytosing the glycocalyx and the electron-dense distal end of the microthrix of the protoscolex tegument. An alteration in the superficial tegumental cytoplasm with extensive mitochondrial damage was also noted. The properties expressed by Kc against protoscolices in vitro might also be relevant for proliferation of metacestodes in vivo.

Animals↗
PubMed1993

Echinococcus granulosus:isoprinosine treatment of the metacestode stage.

The efficacy of short- and long-term treatments with Isoprinosine, an immunomodulatory compound, was studied in Echinococcus granulosus cysts developed in NMRI mice intraperitoneally infected with sheep pulmonary cysts. After treatment, a reduction in the size and number of cysts with macroscopic modifications was observed. The structural alterations included damage or destruction of the protoscoleces and partial destruction of the cyst wall, which predominated at the inner germinal layer level. The efficacy of this drug was evaluated after long-term and short-term treatment. Short-term treatment with a dose of 1 g/kg/day gave better results, with a loss of infectivity of the larval tissue. The well-tolerated long-term treatment with a dose of 2 g/kg/day showed the absence of toxicity of this compound. The survival time of treated animals was greater than that of untreated controls.

Animals↗
PubMed1992

Effects of multiple doses of isoprinosine on Echinococcus multilocularis metacestodes.

Isoprinosine was given at daily doses of 0.5, 1, 2, and 4 g kg-1 of body weight to jirds that were infected for 3 months with Echinococcus multilocularis metacestodes. The effects of the different drug doses on metacestodes were studied by transmission electron microscopy and biochemical methods. At lower doses, increases in uric acid and adenosine deaminase activity were noted. At 4 g kg-1 of body weight, marked ultrastructural damage with metabolic perturbations was observed.

Adenosine Deaminase↗
PubMed1991

In vivo cultivation of Echinococcus multilocularis protoscoleces in micropore chambers.

Micropore chambers containing unevaginated protoscoleces of E. multilocularis were implanted into the peritoneal cavity of AKR mice. Transformation from protoscoleces to fertile multivesicular cysts was obtained after 210 days. Ultrastructural observations of these morphological transformations indicate that a phase of histogenesis follows a phase of dedifferentiation. This morphogenetic process raises the question of the origin of new cell populations. The results reveal the potential role of protoscoleces in secondary echinococcosis and the value of this experimental model for further studies on the larval development.

Animals↗
PubMed1991

Treatment of experimental alveolar echinococcosis: comparative study of mebendazole, isoprinosine and a mebendazole isoprinosine association.

A comparative biochemical study of the effects of mebendazole and Isoprinosine used separately or associated was conducted in six-month old gerbils infected three months ago by Echinococcus multilocularis metacestodes. Mebendazole treatment induced a decrease of glucose (81%) whereas Isoprinosine increased the glucose uptake in the parasite. The combination of the two drugs led to a decrease of about 40% of the glucose concentration. The specific activities of alkaline and acid phosphatases were also modified. Isoprinosine seemed more effective when used alone than associated with mebendazole with the chosen procedure of treatment.

Acid Phosphatase↗
PubMed1991

Life cycles of Echinococcus multilocularis in relation to human infection.

The cycle of Echinococcus multilocularus in natural and synanthropic hosts was investigated during 10 yr in an endemic focus of alveolar hydatid disease in the Massif Central of France. The natural cycle, involving red foxes, Vulpes vulpes, and voles, Arvicola terrestris, existed immediately surrounding a village in which human cases of alveolar hydatid disease occurred. Both foxes and free-ranging dogs could serve as the source of infection for the human population.

Animals↗
PubMed1990

[Epidemiology and prevention of echinococcosis in France].

Echinococcosis is a cosmopolitan parasitic disease caused by the larvae of two tapeworms: Echinococcus granulosus responsible for unilocular hydatidosis, and Echinococcus multilocularis responsible for alveolar hydatid disease. In both cases man is infected by ingesting eggs of these tapeworms belonging to the genus Cestoda. In France, the only animal that acts as definitive host and transmits the unilocular type of hydatid disease is the dog, while the alveolar type is transmitted by dogs, foxes and cats. Carnivorous pet animals must be taken into account in the prevention of echinococcosis, whether their role is direct or indirect (fouling plants).

Animals↗
PubMed1989

Echinococcus multilocularis: a rare cestode of the domestic cat in France.

A cat living in the city of Annemasse (Haute-Savoie) was parasitized by a single minute specimen of the cestode E. multilocularis. The main characteristics of the parasite are described and illustrated. The cat has not previously been reported as one of the definitive hosts of this cestode in France. A potentially serious epidemiological problem is raised by the presence of an infected cat in an urban estate.

Animals↗
PubMed1985

Individual evolution of digestive tract colonization of holoxenic mice by Candida albicans.

Oral administration of various concentrations of Candida albicans to 6-day-old mice established colonization of the digestive tract without mortality. After being weaned (day 21), the development of colonization was studied in a group of mice by daily counting of the number of CFU contained in the feces of each animal. Two features concerning the development of colonization were noted. The course of colonization in individual mice was highly erratic and lead to either transitory or sometimes long-lasting colonization. These results show the importance of a dynamic study of colonization, a condition necessary for any experimental study.

Animals↗
PubMed1980

[Effect of glucose and nitrogen concentrations on the morphology of Candida albicans and the formation of chlamydospores in synthetic culture media].

Candida albicans was grown in the darkness, at 28 degrees C, in a synthetic medium in which glucose and nitrogen concentrations were varied. Numeric appraisal of the chlamydospore index was possible only in the medium where glucose concentration was 0,08 g/1 or less. When the glucose concentration raised, pseudomycelial thalli bore numerous chlamydospores but sometimes also chains of cells with a dense granular content. These thalli bud yeast cells which separate and bud again in the medium. The different morphological aspects of the cultures are decribed, illustrated and classified according to the glucose and nitrogen concentration of the medium.

Ammonium Sulfate↗
PubMed1978

[Study of the Sporothrix schenkii (yeast forms) extract. Electrophoretic and immunoelectrophoretic analyses: characterization of enzymatic activities].

An extract from living yeast forms of S. schenckii was prepared. The yeasts originated from a shake culture in B.H.I. broth (Difco) incubated for 3 days at 35 degrees C in darkness; they were harvested, washed and disrupted with glass beads in a model MSK Braun mechanical cell homogenizer; a freezing-thawing was added to improve the extract. After electrophoretic separation in agarose gel, the extract's components were characterized by their enzymic activity; with this technique, 30 bands were revealed. These enzymic activities were also investigated on the antigenic fractions of the extract revealed by a rabbit hyperimmunserum: 16 among 22 immunoprecipitates are identified by their catalytic properties. Study of the earliest precipitating antibodies (appearing-order and enzymic caracterization) in rabbits just immunized completes this work. How to ameliorate the quality of the extract by culture and extraction conditions is also specified.

Cell-Free System↗
PubMed1976

[Comparative enzymatic study of two strains of Aspergillus fumigatus and of A. fischeri of sapropytic origin or isolated from human or animal lesions: practical diagnostic applications].

14 enzymatic activities (3 dehydrogenases and 11 hydrolases) were systematically investigated in the extracts of 2 strains of Aspergillus fischeri and 14 strains of A. fumigatus (8 isolated from human or animal lesions named 'pathogenic' strains and 6 strains of saprophytic origin). The enzymic composition of A. fumigatus appeared to be very different from one strain to another but no relationships could be established between enzymic differences and origin of the strains. In addition, the immunoelectrophoretic analysis of these antigenic extracts using rabbits immunsera and sera of patients with pulmonary asperigllosis was performed. The type II chymotrypsic activity, corresponding to C arc, was shown more frequently and gave stronger reaction when antigenic extracts from pathogenic strains were allowed to react with sera of patients. Moreover, when sera of patients revealed a same enzymic activity in a saprophytic strain and a pathogenic strain, the number of precipitin lines was significantly larger with the latter one. Accordingly, antigenic extracts used for precipitin tests had to be preferably prepared from pathogenic strains and tested, for value, against sera of patients with pulmonary aspergillosis.

Alkaline Phosphatase↗