Simple fractal method of assessment of histological images for application in medical diagnostics

We propose new method of assessment of histological images for medical diagnostics. 2-D image is preprocessed to form 1-D landscapes or 1-D signature of the image contour and then their complexity is analyzed using Higuchi's fractal dimension method. The method may have broad medical application, from choosing implant materials to differentiation between benign masses and malignant breast tumors.     

Mechanisms ensuring optimal conditions of implantation and embryo development in the pig

The paper summarizes results of a series of studies concerning luteolysis and early pregnancy in pigs. The involvement of the oxytocin (OT)/OT receptor system in the mechanism of corpus luteum (CL) protection during early pregnancy as well as the implication of luteinizing hormone (LH) in the endometrial prostaglandin (PG) release and synthesis are described. In addition, the role of leptin in the regulation of ovarian steroidogenesis and the expression of leptin and its receptor (OB-Rb) genes in hypothalamus, pituitary and reproductive tissues are reported. Moreover, a strong emphasis was placed on the mechanism of PGE2 participation in the local endocrine regulations of reproductive processes occurring in the utero-ovarian area as well as on the vascular endothelial growth factor (VEGF) ligand-receptor system in the ovary and uterus.     

Acyclic sugar analogs of triciribine: lack of antiviral and antiproliferative activity correlate with low intracellular phosphorylation

Triciribine and triciribine monophosphate have antiviral and antiproliferative activity at low or submicromolar concentrations. In an effort to improve and better understand this activity, we have synthesized a series of acyclic analogs and evaluated them for activity against select viruses and cancer cell lines. We conclude that the rigid ribosyl ring system of triciribine must be intact in order to be phosphorylated and to obtain significant antiviral and antiproliferative activity.     

Structural features of microRNA (miRNA) precursors and their relevance to miRNA biogenesis and small interfering RNA/short hairpin RNA design

We have established the structures of 10 human microRNA (miRNA) precursors using biochemical methods. Eight of these structures turned out to be different from those that were computer-predicted. The differences localized in the terminal loop region and at the opposite side of the precursor hairpin stem. We have analyzed the features of these structures from the perspectives of miRNA biogenesis and active strand selection. We demonstrated the different thermodynamic stability profiles for pre-miRNA hairpins harboring miRNAs at their 5'- and 3'-sides and discussed their functional implications. Our results showed that miRNA prediction based on predicted precursor structures may give ambiguous results, and the success rate is significantly higher for the experimentally determined structures. On the other hand, the differences between the predicted and experimentally determined structures did not affect the stability of termini produced through "conceptual dicing." This result confirms the value of thermodynamic analysis based on mfold as a predictor of strand section by RNAi-induced silencing complex (RISC).     

Resistance of human cytomegalovirus to the benzimidazole L-ribonucleoside maribavir maps to UL27

1-(beta-D-Ribofuranosyl)-2,5,6-trichlorobenzimidazole (TCRB) and its 2-bromo analog, BDCRB, are potent and selective inhibitors of human cytomegalovirus (HCMV) DNA processing and packaging. Since they are readily metabolized in vivo, analogs were synthesized to improve biostability. One of these, 1-(beta-L-ribofuranosyl)-2-isopropylamino-5,6-dichlorobenzimidazole (1263W94; maribavir), inhibits viral DNA synthesis and nuclear egress. Resistance to maribavir was mapped to UL97, and this viral kinase was shown to be a direct target of maribavir. In the present study, an HCMV strain resistant to TCRB and BDCRB was passaged in increasing concentrations of maribavir, and resistant virus was isolated. This strain (G2) grew at the same rate as the wild-type virus and was resistant to both BDCRB and maribavir. Resistance to BDCRB was expected, because the parent strain from which G2 was isolated was resistant due to known mutations in UL56 and UL89. However, no mutations were found in UL97 or other relevant open reading frames that could explain resistance to maribavir. Because sequencing of selected HCMV genes did not identify the resistance mutation, a cosmid library was made from G2, and a series of recombinant G2 wild-type viruses were constructed. Testing the recombinants for sensitivity to maribavir narrowed the locus of resistance to genes UL26 to UL32. Sequencing identified a single coding mutation in ORF UL27 (Leu335Pro) as the one responsible for resistance to maribavir. These results establish that UL27 is either directly or indirectly involved in the mechanism of action of maribavir. They also suggest that UL27 could play a role in HCMV DNA synthesis or egress of HCMV particles from the nucleus.     

Triple eradication therapy counteracts functional impairment associated with Helicobacter pylori infection in Mongolian gerbils.

Gastric Helicobacter pylori (Hp) infection in Mongolian gerbils is an established experimental model of gastric carcinogenesis resulting from the long-term Hp infection but functional aspects accompanying this Hp-induced progression from gastritis to the cancer, especially changes in gastric acid secretion, gastric blood flow (GBF) and gastrin-somatostatin link have been little studied. It is unclear whether Hp eradication therapy alters the functional and the histopathological changes in this animal model of Hp-infection. We examined the effects of intragastric (i.g.) inoculation of Mongolian gerbils with Hp strain (cagA+ vacA+, 5 x 10(6) CFU/ml) that had been isolated from a patient with gastric ulcer as compared to those induced by vehicle (saline) in gerbils with or without gastric fistula (GF) at 1.2, 4, 6, 9, 12 and 30 wks upon gastric inoculation with this bacteria. An attempt was made to evaluate the influence of anti-Hp triple therapy with omeprazole, amoxicillin and tinidazol on gastric Hp-infection and Hp-induced functional impairment of the gastric mucosa. Gastric mucosal biopsy specimens were taken for the assessment of the morphological changes and the presence of Hp infection using rapid urease test (CLO-test) and the density of Hp-colonization were assessed by counting of the number of bacterial colonies per plate. Gastric blood flow (GBF) was measured by H2-gas clearance technique and the venous blood and the gastric content were collected for the measurement of plasma gastrin levels and the gastric luminal somatostatin level by radioimmunoassay (RIA). The Hp in gastric mucosa was detected in all animals by culture and rapid urease test at various periods upon Hp inoculation. Basal gastric acid in non-infected conscious gerbils with GF reached the level of about 28 +/- 4 micromol/h and this was reduced by over 50% immediately upon the Hp-inoculation and persisted for time intervals tested up to 30 wk. Early lesions were seen 4 wks after the Hp-inoculation and consisted of chronic gastritis with thickened gastric mucosal foldings and elongated interfoveolar ridges. Edema and congestion as well as significant mucosal inflammatory infiltration with lymphoid infiltrate in lamina propria of the mucosa occurred in all infected gerbils. Adenomatous hyperplasia with cellular atypia was observed at 12 wk upon Hp-inoculation together with increased mitotic activity and numerous apoptotic bodies formation, while lamina propria was reduced leaving dilated atypical gastric gland situated "back-to-back". This glandular atypia failed to show lamina propria or submucosa infiltration corresponding to gastric intraepithelial neoplasia. The GBF in Hp-infected gerbils was significantly lower, and a 6-7 fold increase in plasma gastrin levels combined with a significant fall in gastric luminal somatostatin contents observed at all tested periods as compared to vehicle-controls and these effects were counteracted by anti-Hp triple therapy. We conclude that: 1). Hp-infection in Mongolian gerbils in early stages before adenocarcinoma formation results in the development of typical functional and pathological changes such as suppression of gastric secretion and impairment of both, gastric mucosal microcirculation and gastrin-somatostatin link, and 2). this deleterious influence of Hp on gastric morphology and gastric functions is greatly attenuated in gerbils treated with Hp-eradication therapy.     

Effect of growth hormone and insulin-like growth factor-I on spontaneous apoptosis in cultured luteal cells collected from early, mature, and regressing porcine corpora lutea

The aim of the present study was to test the hypothesis that growth hormone (GH) and insulin-like growth factor-I (IGF-I) act at a local level to inhibit luteal cell apoptosis. Luteal cells collected from the corpora lutea at different stages of the luteal phase were cultured for 24 h in M 199 medium supplemented with 5% of calf serum to cause attachment cells to the plastic. After 24 h, the media were changed and various concentrations of GH (10, 100 or 200 ng/ml) or IGF-I (30, 50 or 100 ng/ml) were added to the culture medium. Twenty-four hours later, cells were fixed for morphological assessment of apoptotic cells utilising a Hoechst staining technique. To support morphological observations, measurements of caspase-3 activity in cultured porcine luteal cells were performed. Increased incidence of apoptotic bodies and caspase-3 activity accompanied luteal regression and was associated with a decreased progesterone (P4) secretion by luteal cells. GH stimulated P4 secretion by luteal cells collected from developing (ELP) and mature (MLP) corpora lutea but had no effect on its secretion by cells collected from regressing corpora lutea (LLP). Moreover, it had no effect on the incidence of apoptotic bodies in all types of corpora lutea. However, suppression of caspase-3 activity was observed with 100 and 200 ng of GH/ml in all types of corpora lutea. IGF-I had a stimulatory effect on P4 secretion by ELP and MLP, decreased the incidence of apoptotic bodies and suppressed caspase-3 activity in cultures treated with all doses used. In conclusion, our results indicate that both GH and IGF-1 trigger anti-apoptotic effects either indirectly, by increasing progesterone secretion, or directly, through the inhibition of caspase-3 activity and subsequent prevention of apoptotic body formation.     

Predation on rodents in Białowieza primeval forest, Poland

Autumn and winter predation on bank vole Clethrtonomys glareolus and yellow-necked mouse Apodemus flavicollis was studied in 1985/86-88/89 in an 11 2 km² area of the Bialowieza National Park Rodents regularly increased in numbers from spring to autumn and decreased throughout winter Out of 23 species of predators, the most common were tawny owl Strix aluco (43-57 adult ind 10 km⁻²) weasel Mustela ntvahs (17-27 ind), buzzard Buteo buteo (12-16) and pine marten Martes martes (5-8) Voles and mice were the staple food for two specialists the stoat Mustela erminea and the weasel, and two generahsts the tawny owl and the pine marten The generalists exploited different alternative prey when rodents were scarce tawny owl -amphibians, marten - small mammals, and the red fox Vulpes vulpes - ungulate carcasses and hares The depth of snow and abundance of voles were two major factors shaping the contribution of voles to tawny owl and marten diets No such relationships were found for mice and generalist predators The predation by 8 species (tawny owl, buzzard, marten, weasel, stoat, polecat Mustela putortus fox, and raccoon dog Nyctereutes procyonoides) from 1 October to 15 April in 1986/87, 87/88, and 88/89 was estimated to be on average 28-35 voles and 14-17 mice ha Estimates suggested that three species were responsible for 86-95% of the total predation impact tawny owl (56-71%), weasel (11-21%) and marten (10-15%) The predation impact was similar to the annual decrease in rodent numbers from autumn till spring voles 35 (SD 111) lnds ha^-1in autumn and 8 (SD 2 6) lnds ha^-1in spring, and mice 24 (SD 16 3) mds ha⁻¹ in autumn and 3 (SD 2 5) in spring Predation, therefore, was regarded as the main agent of rodent mortality throughout autumn and winter     

Fatty acids diffusion in lecithin multilayers: hydration and PH effects.

The diffusion of the sodium salt of monocarboxylic fatty acids, from formate to stearate, has been studied as a function of water content and pH in lecithin--water lamellar phases. Evolution of the diffusion coefficients with increasing chain length reflects the different localizations of fatty acids in the system. From formate to butyrate, which are mainly restricted to the hydrophilic layer of the phase, diffusion rates decrease rapidly. From butyrate to stearate, fatty acids (anchored at the hydrophilic--lipophilic interface) undergo lateral diffusion and then the decrease of D with increasing chain length is much slower. The diffusion of stereate is already comparable to the diffusion of the lecithin molecule itself. The diffusion rates strongly depend upon phase hydration and pH: it is shown that both parameters control the fatty acid ionization. The variations in diffusion rates observed may be ascribed to the fact that, depending upon their state of ionization, fatty acids assume a different localization and therefore experience different interactions in the lamellar system.