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High performance thin-layer chromatography was used to determine the concentration of β-carotene and lutein in the whole body and digestive gland-gonad complex (DGG) of uninfected Biomphalaria glabrata snails and those infected with Schistosoma mansoni for 6 and 8 weeks. Pigments were extracted from the snails using acetone and separated on EMD Millipore reversed phase C-18 plates with concentration zone using petroleum ether-acetonitrile-methanol (1:1:2) mobile phase. After development, two yellow pigment zones, lutein and β-carotene, were identified with respective R f values of 0.55 and 0.13 and then quantified by densitometry. Statistical analysis of the weight percentages of each pigment showed a significant decrease (P < 0.05) in the concentration of β-carotene in the DGGs of infected B. glabrata at 6 and 8 weeks post-infection compared to the uninfected snails. No significant differences were seen in the concentrations of β-carotene in the whole body of the uninfected versus infected snail samples. Changes in the lutein concentration of the infected DGG and whole snail bodies were insignificant compared to the uninfected controls. In conclusion, larval S. mansoni infection caused a significant decrease in the β-carotene concentration of the DGG at 6 and 8 weeks post infection.
Effects of the presence of sporocysts, rediae and cercariae of Fasciola hepatica on the lipid content in the digestive gland of Lymnaea truncatula as well as on lipid levels in tissues of the parasites themselves were studied. Lipids were examined by means of histochemical and cytophotometric techniques. The snail's digestive gland lipid level was found to be almost halved in 20 days post infection; a more then 80% reduction being visible after the subsequent 40 and 60 days. The loss of lipids in the digestive gland of the infected snails point at mobilisation of lipid energy reserves to compensate for the deficiency of carbohydrates, used by these parasites. The parasite tissues such as tegument, pharynx, suckers and germ balls showed considerable lipid contents and were metabolically active. It supports the hypothesis that lipids are used as energy source by developmental stages of this parasite.
Two cercariae, one of them ocellate and with well developed tail (Monorchiidae) and another apharyngeate brevifurcocercous (Aporocotylidae), parasite of Amiantis purpurata (Lamarck, 1818) (Bivalvia, Veneridae) from the Patagonian coast on the Southwestern Atlantic Ocean, are described. These reports comprise the second monorchiid intramolluscan infection reported for the Southern Hemisphere and first intramolluscan aporocotylid for the Southern Hemisphere. In addition, this constitutes the first report of aporocotylid intramolluscan stages (parthenita) occupying only the haemocoel of the gills of a marine molluscan host rather than the digestive gland and gonad, the usual site of infection.
At the turn of XIX and XX century, the principal concept explaining the mechanism of secretory activity of the digestive glands was nervism proposed by I. P. Pavlov at Russian physiological school in St Petersburg, and this dogma was widely recognized for several years in other countries. The discovery of secretin in 1902 by W.B. Bayliss and E.H. Starling, and then of gastrin in 1906 by J.S. Edkins, emphasized the hormonal regulation of pancreatic and gastric secretion, respectively. In 1943, A.C. Ivy and E. Olberg discovered a hormone, which contracts the gallbladder - cholecystokinin (CCK), while A. Harper and H.S. Raper described another hormone, pancreozymin, which stimulated pancreatic enzymes. It required over twenty years, however, for these and many other hormones to be identified, purified and synthesized due to the extensive work of several teams including R. Gregory, G. Dockray and Kenner of the UK; J. Rehfeld of Denmark and E. Wunsch of Germany for their work on gastrin; E. Jorpes and V. Mutt of Sweden and N. Yahaihara of Japan for their work on secretin and other GI hormones including, CCK, vasoactive intestinal peptide (VIP), gastric inhibitory peptide (GIP), motilin, gastrin-releasing peptide (GRP) and others peptides. CCK and pancreaozymin were found by E. Jorpes and V. Mutt to represent structurally a common messenger for pancreatico-biliary secretion. This rapid development of GI endocrinology in the 1960s and 1970s could be attributed to the application of peptide biochemistry in characterizing various peptide hormones. The technique of radioimmunoassay by S.A. Berson and R.S. Yalow in 1959 measured minute amounts of hormones in the circulation and tissue, and the technique of immunocytochemistry detected the cellular origin of these hormones. Further progress in molecular biology led to sequencing GI hormones and their prohormones, and opened a new area of investigation for the physiological role of these hormones in the mechanism of digestive gland secretion, motility of gastrointestinal tract, visceral blood flow, tissue growth and integrity in health, as well as in various digestive diseases. Overall, apparent divergent concepts, the nervous control (Pavlov) and hormonal control (Bayliss and Starling), greatly facilitated the elucidation of the interacting neuro-hormones during the cephalic, gastric, and intestinal phases of gastric and pancreatic secretion in health and digestive diseases. Although Polish contributions in the early phase of GI endocrinology concerned mostly gastric inhibitory hormones such as enterogastrone and urogastrone, major Polish traces can be detected in the elucidation of origin and physiological role and pathological involvement of gastrin, CCK, secretin, motilin, gastric inhibitory peptide and the most recent additions of enterohormones such as epidermal growth factor, somatostatin, leptin or ghrelin. Major achievements have been obtained in gastric and colorectal cancerogenesis involving gastrin and its precursor, progastrin.
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