Effect of developing Sarcocystis muris tissue cysts on ultrastructural change of murine muscle fibers

A study was made of the influence exerted by developing sarcocysts of Sarcocystis muris on the ultrastructural organization of muscle fibres, both harbouring the sarcocysts (HSM) and sarcocyst-free (SFM), from skeletal muscles of experimentally infected mice. Muscle fibres of non-infected mice of the same age served as a control. Mice were sacrificed 6 months following feeding S. muris oocysts (or sporocysts). The developing sarcocysts seriously destroyed HSM: their myofilaments were no hold in register, cross-bridges almost entirely disappeared, M-lines and Z-disks looked as broken structures. The majority of actin myofilaments were arranged along myosin myofilaments as discrete units. The host cell sarcoplasm was packed with numerous vacuoles of different form and size. Compared to muscle fibres in the control, SFM of infected mice also displayed an obvious ultrastructural alteration. On the periphery of SFM, some destroyed sarcomeres with swollen myofilaments were noticed whose cross-bridges were totally lacking. In other extreme areas myosin and actin myofilaments were disintegrated into thin straightened filaments 2.0-2.5 nm in diameter. It is supposed that HSM and SFM of the infected mice may experience different kinds of influence on the part of the developing intracellular parasite (sarcocyst). And it dos not seem unlikely that various biologically active substances, produced by the parasite, may be vesicle transported to SFN through the endomysium space.     

Guanylin and related peptides.

Guanylin and uroguanylin are short peptides homologous to heat-stable enterotoxins of Escherichia coli and other enteric bacteria. Guanylin and uroguanylin are synthetized from the respective prepropeptides mainly in gastrointestinal mucosa and are secreted both into intestinal lumen and into the blood. Luminally secreted peptides stimulate chloride and bicarbonate secretion in the intestine through the mechanism involving guanylate cyclase C receptor, cyclic GMP, protein kinase G and cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel. Bacterial enterotoxins, which have greater potency than endogenous peptides, induce excessive fluid secretion into intestinal lumen leading to secretory diarhea. Uroguanylin is expressed mainly in enterochromaffin cells of duodenum and proximal small intestine whereas guanylin is abundant in goblet cells of colonic epithelium. Uroguanylin and guanylin increase urinary sodium and potassium excretion both as circulating hormones and as paracrine mediators produced within the kidney. Uroguanylin functions as "intestinal natriuretic hormone" which is secreted in response to oral sodium loading and maintains sodium balance during postprandial period. Plasma and urinary concentrations of guanylin and uroguanylin increase in renal failure and heart failure. Guanylin peptides possess antiproliferative activity in intestinal cells culture and their expression decreases in colonic carcinoma indicating that their deficiency may contribute to the pathogenesis of this disease.     

Swimming stress-induced histochemical and morphological changes in various regions of the rat hippocampus

In rats, swimming stress enhanced functional activity of the hippocampus' pyramidal neurones as manifested by diminishing of the glycogen contents, increasing amount of nucleic acids, augmented nucleus/cytoplasm ratio.     

The effect of branching angle on adaptive growth in patchy environments

In clonal plants, the genetic individual (genet) develops via the production of multiple physiological individuals (ramets). The branching angle between the ramets can significantly influence the shape of the developing clone. We investigated the adaptive significance of this phenomenon by means of a spatially explicit dynamic model of clonal growth. We studied the effect of the branching angle on the efficiency of filling habitat patches, varying the sizes and shapes of the patches. Two growth forms were compared: the Narrow Range (NR) versus Wide Range (WR) form. In the NR plant, the branching angle was always acute, while in the WR plant, both acute and wide angles could occur. We hypothesized that the NR plant would be less successful, as narrower branching constrained the plant’s ability to turn. The simulations revealed an opposite trend: the NR plant occupied more space in most of the simulated habitats. However, the effect was weak in general. We conclude that the branching angle between ramets is likely to be a neutral trait in terms of natural selection.     

Demographic, temporal and environmental effects on the frequency of cribra orbitalia in three Early Medieval populations from western Slovakia

The frequency of cribra orbitalia was examined in Early Medieval skeletal samples from Devín and Borovce (Slovakia). The effects of environmental and socio-economic factors on the distribution of orbital lesions are explored and discussed. The frequency of cribra orbitalia was lowest in Devín-Hrad (11th-12th c. A.D.), followed by Devín-Za kostolom (9th c. A.D.) and Borovce (8th-beginning of 12th c. A.D.). The increased frequency of cribra orbitalia at Borovce can be attributed to inadequate sanitation and increased pathogen load at this rural site compared to urban Devín. Borovce (BO) sub-adults displayed orbital lesions significantly more frequently than BO adults and sub-adults in the Devín-Za kostolom (FR) and Devín-Hrad (DH) samples. Although the total mortality of sub-adults did not differ between the sites, BO sub-adults with cribra orbitalia showed a considerably higher mortality. Their counterparts from FR and DH showed similar mortality patterns irrespective of the presence of orbital lesions. As in most reference samples, no significant sex differences in the frequency of cribra orbitalia were observed in BO, DH and FR. However, a considerably increased mortality was observed in young males from Devín-Hrad irrespective of the presence of orbital lesions. This finding can be attributed to their involvement in violent conflicts. Reference data from Medieval Central European skeletal samples suggest that an increased occurrence of cribra orbitalia was associated with crop failures, migration and interpersonal conflicts. These factors favour the spread of and vulnerability to infectious diseases, which are considered to be the major cause of iron deficiency anaemia.     

Substrate specificity and some properties of free and immobilized animal alpha-L-fucosidase]

The effect of a partially purified preparation of pig kidney alpha-L-fucosidase on some glycoproteins--human and rabbit gamma-globulin, glycoprotein from sheep submaxillary gland and ceruloplasmin--was studied. It was shown that the action of the enzyme of the glycoproteins was not accompanied by a release of fucose. A comparative study of the properties of free and concanavalin A-Sepharose 4B-bound alpha-L-fucosidase was done. The experimental data is indicative of difference in the pH-dependenced and thermostability of these two enzyme forms. It was found that bound alpha-L-fucosidase, similar to the free form, did not split off fucose from the native blood group substances. The data of isoelectric fucosing of alpha-L-fucosidase suggests the existence of enzyme polymorphism.     

Interaction of sheep haptoglobin with trypsin inhibitors

It was found that polymeric sheep haptoglobin C interacts with duck egg ovomucoid and with maize trypsin inhibitor. These inhibitors do not block the region in haptoglobin C molecule which is responsible for the formation of its complex with hemoglobin. The binding of the natural protein inhibitors is suggestive of homology of the haptoglobin site involved in the interaction with the substrate-specific site of trypsin. It is assumed that the regions in these protein molecules adjacent to the active and specific sites also possess a high degree of homology.     

trypsin inhibition by sheep haptoglobin

It was found that sheep haptoglobin causes non-competitive inhibition of trypsin. The enzyme inactivation is due to its interaction with haptoglobin. MetHb and thionine do not influence the efficiency of haptoglobin as a trypsin inhibitor. It is concluded that the haptoglobin molecule has a trypsin-binding site which differs from the sites responsible for the interaction with MetHb and thionine.