Differences in the compatibility of infection between the liver flukes Fascioloides magna and Fasciola hepatica in a Colombian population of the snail Galba sp.

Experimental infections of Galba sp. (origin, Colombia) with allopatric isolates of Fasciola hepatica from France or Fascioloides magna from the Czech Republic were carried out during five successive snail generations to determine if this lymnaeid might sustain complete larval development of either parasite. In snails exposed to F. hepatica, 7 of 400 snails harboured several rediae and only two snails contained a small number of free cercariae on day 50 post-exposure. In contrast, the intensity of F. magna infection in Galba sp. progressively increased from the F1 to F5 generations. Spontaneous cercarial shedding of F. magna occurred in 7 of 100 Galba sp. belonging to the F5 generation and the number of shed cercariae did not differ significantly from that noted in control Galba truncatula of French origin. Galba sp. from Colombia can be added to the list of potential intermediate hosts for F. magna.

Growth rate of the intermediate snail host Galba truncatula influences redial development of the trematode Fascioloides magna.

A total of 850 pre-adult Galba truncatula (shell height, 4 mm), originating from four French snail populations differing in shell height at the adult stage (from 6.5 to 12 mm), were individually subjected at 20°C to single-miracidium infections with Fascioloides magna. At day 75 post-exposure, the surviving snails were dissected, and rediae and cercariae were counted. Snail groups differed in shell growth during the experiment: from 1.8 ± 0.4 mm in group A up to 4.0 ± 1.1 mm in group D. The prevalence of F. magna infection, the numbers of free rediae and cercariae significantly increased together with increasing growth of infected snails during the experiment. Group A produced 1-6 first-generation rediae per snail and the mean daughter redia production ranged from 7.5 second-generation rediae (when a single first generation per snail developed) to 2.3 (6 first-generation rediae per snail). In contrast, up to ten first-generation rediae were noted in group D, and each mother redia gave daughter rediae with averages ranging from 1.5 (ten first-generation rediae per snail) to 13 (a single first generation per snail). In conclusion, the development of F. magna in G. truncatula exhibited both inter- and intrapopulation variability, where the development of rediae and cercariae was positively correlated with snail growth.

Lymnaea neotropica and Lymnaea viatrix, potential intermediate hosts for Fascioloides magna.

Experimental infections of two South American lymnaeid populations with Fascioloides magna were carried out to determine whether these snails may sustain larval development of this digenean and, if so, to quantify their potential for cercarial production. The reference group was a French population of Galba truncatula infected and raised according to the same protocol. According to the internal transcribed sequence (ITS)-1 segment of their genomic rDNA, these South American populations were identified as Lymnaea neotropica (origin, Argentina) and Lymnaea viatrix var. ventricosa (origin, Uruguay). In the snail groups followed for cercarial shedding, longer prepatent periods and lower numbers of shed cercariae were noted in South American lymnaeids. In other snails dissected at day 65 post-exposure, the redial and cercarial burdens of F. magna found in the bodies of L. neotropica and L. v. ventricosa were significantly lower than those noted in G. truncatula. Compared to the total cercarial production noted in the dissected snails, the percentage of cercariae that exited from snails was 51.3% for G. truncatula, 32.2% for L. neotropica and 46.8% for L. v. ventricosa. The two South American species of snails can thus be considered as potential intermediate hosts of F. magna.

Myelin lipids in ischemic stroke.

Slices of ischemic focus (infarct area) and of the contralateral frontal lobe were submitted to histological and biochemical studies. The obtained results indicate that in stroke cases the necrotic focus as well as contralateral brain hemisphere are characterized by a marked decrease of cholesterol and cerebrosides content and an increase of lysophosphatidylcholine and cholesterol esters in the myelin fraction. We conclude that ischemia as well as the degenerative aging process are both responsible for the abnormal lipid pattern in the myelin of the white matter in stroke cases. The long lasting hypoxia resulting from cerebral vessel atheromatosis contributes to biochemical changes in the myelin of the apparently healthy white matter of the contralateral hemisphere in brain infarction.

Pattern of myelin proteins in moderate hypoxia.

Myelin proteins isolated from the brain of Wistar rats subjected to moderate hypoxia (7% of oxygen in a respiration gaseous mixture) for 30 min were investigated. Among the various protein fractions Wolfgram protein happened to be most markedly affected, demonstrating considerably lowered percentages in all experimental groups, starting from 24 h after hypoxia. Our findings compared with those obtained in other experimental conditions lead to the conclusion that changes in the myelin protein pattern are characteristic for particular morbid processes evoked by various pathogenic factors. The demyelination is concomitant with severe loss of basic proteins, whereas myelin lesions of other types are connected with changes in protein of higher molecular mass.

Myelin lipids of the rat brain in experimental hypoxia.

The pattern of cerebral myelin lipids was studied in Wistar rats exposed to mild hypoxia (7% of oxygen in a respiratory mixture) for 30 min. The most pronounced change involved a marked increase in cholesterol esters and lysophosphatidylcholine content in the myelin fraction. The results obtained indicate that mild hypoxia induces a lesion of myelin membranes but does not provoke the reaction of lymphocytes and macrophages, which by production of myelinolytic factors, evoke demyelination.

Lipids of the oligodendroglial fraction in methylnitrosourea induced encephalopathy.

The investigations were performed on oligodendroglial cells isolated from the cerebral white matter of Wistar rats treated intravenously with a 3% solution of MNU at a dose of 60 mg/kg body weight. The oligodendroglial fraction showed a decrease of the sphingomyelin, phosphatidylserine and phosphoinositides content. The observed changes correlated with alterations of the lipid spectrum found in the myelin fraction of MNU intoxicated rats. This would indicate that MNU acting in the central nervous system affects in a similar way the lipid metabolism of both components of the oligodendroglia-myelin system.