EFFECT OF BIOMPHALARIA ALEXANDRINA SNAILS INFECTED BY BACILLUS THURINGIENSIS KURSTAKI ON THREE SUCCESSIVE GENERATIONS OF SCHISTOSOMA MANSONI

The effect of infection of Biomphalaria alexandrina snails with Bacillus thurin-giensis kurstaki on various stages of Schistosoma mansoni life cycle was studied for three successive generations. Thus, two groups of snails were exposed to a sublethal concentration of the bacteria (0.08 gm/L water) containing 32000 IU/mg, for one week and to schistosome miracidia. One group was exposed to the miracidia before bacterial infection, while the other group to the miracidia after the bacterial infec-tion. Cercariae produced from each group of snails were used to infect albino mice. The infection of snails and mice with the parasite was repeated for three generations of the parasite. In the first case, data obtained show that the schistosome infection rate of snails was considerably reduced being 60%, 18%, and 66.6% versus 90 % , 92% and 90% in untreated control snails in the three generations of the parasite, re-spectively. Meanwhile, the mean prepatent period was extended being 29.1 4.3 days, 33 1 days and 38.5 2.5 days versus 27 days in the control group. The num-ber of worms recovered from infected mice showed reduction of 52 %, 78.4% and 58.6%, respectively. In the second case, the infection rate of snails was 40%, 16% and 73.7% for the three successive parasite generations and the prepatent period was 32 1 days, 32 2.3 days and 35 2.8 days, respectively. The reduction percentage of the recovered worms was 34.8, 73.6 and 72.9 in the sccessive generations, respec-tively. The present results prove that infecting B.alexandrina snails with a sublethal concentration of B. thuringiensis kurstaki bacteria exhibits clear negative effect on the transmission of S. mansoni in three successive generations. So, it could be rec-ommended to use B. thuringiensis kurstaki as a potential biocontrol agent against S. mansoni

Bioactivity of miltefosine against aquatic stages of <it>Schistosoma mansoni, Schistosoma haematobium </it>and their snail hosts, supported by scanning electron microscopy

Abstract Background Miltefosine, which is the first oral drug licensed for the treatment of leishmaniasis, was recently reported to be a promising lead compound for the synthesis of novel antischistosomal derivatives with potent activity in vivo against different developmental stages of Schistosoma mansoni. In this paper an in vitro study was carried out to investigate whether it has a biocidal activity against the aquatic stages of Schistosoma mansoni and its snail intermediate host, Biomphalaria alexandrina , thus being also a molluscicide. Additionally, to see whether miltefosine can have a broad spectrum antischistosomal activity, a similar in vitro study was carried out on the adult stage of Schistosoma haematobium, the second major human species, its larval stages and snail intermediate host, Bulinus truncutes. This was checked by scanning electron microscopy. Results Miltefosine proved to have in vitro ovicidal, schistolarvicidal and lethal activity on adult worms of both Schistosoma species and has considerable molluscicidal activity on their snail hosts. Scanning electron microscopy revealed several morphological changes on the different stages of the parasite and on the soft body of the snail, which further strengthens the current evidence of miltefosine's activity. This is the first report of mollusicidal activity of miltefosine and its in vitro schistosomicidal activity against S.haematobium. Conclusions This study highlights miltefosine not only as a potential promising lead compound for the synthesis of novel broad spectrum schistosomicidal derivatives, but also for molluscicidals.</p

Resistance of Biomphalaria alexandrina to Schistosoma mansoni and Bulinus truncatus to Schistosoma haematobium Correlates with Unsaturated Fatty Acid Levels in the Snail Soft Tissue

Only a fraction of the Biomphalaria and Bulinus snail community shows patent infection with schistosomes despite continuous exposure to the parasite, indicating that a substantial proportion of snails may resist infection. Accordingly, exterminating the schistosome intermediate snail hosts in transmission foci in habitats that may extend to kilometres is cost-prohibitive and damaging to the ecological equilibrium and quality of water and may be superfluous. It may be more cost effective with risk less ecological damage to focus on discovering the parameters governing snail susceptibility and resistance to schistosome infection. Therefore, laboratory bred Biomphalaria alexandrina and Bulinus truncatus snails were exposed to miracidia of laboratory-maintained Schistosoma mansoni and S. haematobium, respectively. Snails were examined for presence or lack of infection association with soft tissue and hemolymph content of proteins, cholesterol, and triglycerides, evaluated using standard biochemical techniques and palmitic, oleic, linoleic, and arachidonic acid, assayed by ultraperformance liquid chromatography-tandem mass spectrometry. Successful schistosome infection of B. alexandrina and B. truncatus consistently and reproducibly correlated with snails showing highly significant (up to P<0.0001) decrease in soft tissue and hemolymph content of the monounsaturated fatty acid, oleic acid, and the polyunsaturated fatty acids, linoleic, and arachidonic acids as compared to naïve snails. Snails that resisted twice infection had soft tissue content of oleic, linoleic, and arachidonic acid similar to naïve counterparts. High levels of soft tissue and hemolymph oleic, linoleic, and arachidonic acid content appear to interfere with schistosome development in snails. Diet manipulation directed to eliciting excessive increase of polyunsaturated fatty acids in snails may protect them from infection and interrupt disease transmission in a simple and effective manner

Spectral resolution and simultaneous determination of oxymetazoline hydrochloride and sodium cromoglycate by derivative and ratio-based spectrophotometric methods

Sodium cromoglycate (SCG) and oxymetazoline hydrochloride (OXMT) are administered in combination for effective treatment of nasal congestion and allergy. In this work, SCG was determined using direct spectrophotometry by measuring its zero order absorption spectra at its λmax 320.6 nm where OXMT showed zero absorbance. On the other hand, four simple, sensitive and precise spectrophotometric methods were developed and validated for the determination of OXMT in the presence of SCG in their laboratory prepared mixtures and pharmaceutical formulation, without preliminary separation; Method A: first derivative spectrophotometric method [1D], Method B: first derivative of ratio spectra method [1DD], Method C: ratio difference spectrophotometric method [RDSM] and Method D: ratio subtraction method [RSM]. Ratio manipulating methods (Method B, C and D) were done using divisor of 10.00 µg/mL SCG. Linear correlation was obtained in range 4-22 µg/mL for OXMT by methods A, B and D and 6-22 µg/mL for method C. All methods were validated in compliance with the International Conference on Harmonization (ICH) guidelines and satisfactory results were obtained. No significant difference was noted between the developed methods and the official one with respect to accuracy and precision

Development and validation of stability-indicating methods for determination of torsemide

Four sensitive and precise methods for determination of torsemide in presence of its degradation product and in pharmaceutical formulation were developed and validated. Method A is the second derivative spectrophotometry at 262.4 nm with mean percentage recoveries 100.06±0.75. Method B is first derivative of the ratio spectra spectrophotometry, at 232.4, 244.6 nm and at the total peak amplitude from the maximum at 232.4 nm to the minimum at 244.6 nm (1DD232.4+244.6nm). Method C is a TLC-densitometric one, for torsemide separation using acetone : chloroform : ethyl acetate (4:4:2 v/v) as a developing system. Method D is HPLC one, it provides complete separation of torsemide from its degradation product on C8 column with UV detection at 287 nm and recovery 99.98±0.76. The proposed methods have been successfully applied to the analysis of torsemide in pharmaceutical formulations without interference from other additives and the results were statistically compared with the official method. DOI: http://dx.doi.org/10.4314/bcse.v30i1.