Molecular modeling of the neurohypophyseal receptor/atosiban complexes

The neurohypophyseal nonapeptide hormone oxytocin (OT) is the strongest uterotonic substance known and is responsible for the initiation of labor. Conversely, oxytocin antagonists blocking uterine OT receptor can suppress uterus contraction. In this paper we describe a computer simulated docking pertinent to affinity of an oxytocin antagonist atosiban towards OT receptor, versus vasopressin V1a and V2 receptors.     

Some problems of forest transformation at the transition to the oligocratic/<Emphasis Type="Italic">Homo sapiens</Emphasis> phase of the Holocene interglacial in northern lowlands of central Europe

The paper discusses the main changes in the composition of mixed deciduous forests which occurred mostly between 5,000 and 2,000 b.p., based on selected pollen diagrams from the lowlands of Germany, Denmark and Poland, and including two pollen diagrams from varved sediments, used as reference sites, and on isopollen maps for Poland. The Ulmus retreat is shown on maps, and additional data for its pathogenic origin are presented. Corylus declines at ca. 3,500 b.p. at both reference sites, and its connection with Fagus expansion in the west and Carpinus expansion in the east is discussed. The nature of post-Atlantic transitory shrub–forest communities with dominant Corylus and Quercus is presented. Relationships between the history of Fagus and Carpinus and the development of human settlements are shown. Human impact has been admitted as one of the most important driving forces determining vegetational development since the time of fully developed Neolithic cultures. Other very important abiotic factors were the climate (particularly after 2,500 b.p.), and soil degradation.     

Tanaidacea (Crustacea,Malacostraca) of two polar fjords: Kongsfjorden (Arctic) and Admiralty Bay (Antarctic)

The tanaidacean faunas of two polar fjords, Kongsfjorden (Arctic) and Admiralty Bay (Antarctic), were compared. The results show that Tanaidacea in the southern fjord are more diversified than those in the northern one. This difference is especially evident in species richness (12 species vs 3 species, respectively), but is not too significant in terms of diversity. In both polar fjords, the highest densities of tanaids were noted in sites where mud was swept off by the water current or eroded off steep bottom expoing coarser mineral particles used for tube building. The distribution of tanaids is suggested to be based on the joint action of inter alia factors such as the quality of bottom sediments, sedimentation ratio, accessibility of food, predation pressure, behaviour and heterogeneity of habitats.An erratum to this article can be found at     

Comparative analysis of RCAS1 level in neoplasms and placenta

The tumor associated antigen RCAS1 (receptor-binding cancer antigen expressed on SiSo cells) expressed with high frequency in various cancer and trophoblast cells, inhibits growth of estrogen receptor-expressing cells and induces apoptosis. Because previous reports demonstrated RCAS1 presence only by non-quantitative immunocytochemistry methods, we decided to use a Western blotting with anti-RCAS1 monoclonal antibodies for estimation of the relative content of the tumor-associated antigen. One hundred tissue samples were assayed (neoplasms, chronic inflammatory diseases, healthy tissues, trophoblasts and placentas at term). RCAS1 was present in all neoplastic, placental and trophoblast tissue samples and its level in malignant samples was statistically significantly higher than in benign neoplasms. The amount of RCAS1 in chronic inflammations was also significantly increased in immune mediated diseases, like allergic nasal polyps and sarcoidosis. The RCAS1 protein was not revealed in healthy mucous membrane and in muscle tissues. The presented results suggest that RCAS1 might play an important role in tumor escape from host immunological surveillance and carry weight in the down regulation of the maternal immune response, thereby maintaining pregnancy.     

Kinetics of increased generation of (.)NO in endotoxaemic rats as measured by EPR

Ferrous-diethyldithiocarbamate (Fe(DETC)(2)) chelate is a lipophilic spin trap developed for (.)NO detection by electron paramagnetic resonance (EPR) spectroscopy. Using this spin trap we investigated the kinetics of (.)NO production in endotoxaemia in rats induced by lipopolysaccharide (Escherichia coli, 10 mg/kg). The NO-Fe(DETC)(2) complex was found to give a characteristic EPR signal, and the amplitude of the 3rd (high-field) component of its hyperfine splitting was used to monitor the level of (.)NO. We found that in blood, kidney, liver, heart and lung (.)NO production starts to increase as early as 2 h after LPS injection, reaches the maximum 6 h after LPS injection and then returns to basal level within further 12-18 h. Interestingly, in the eye bulb the maximum of (.)NO production was detected 12 h after LPS, and the signal was still pronounced 24 h after LPS. In brief, the highly lipophilic exogenous spin trap, Fe(DETC)(2) is well suited for assessment of (.)NO production in endotoxaemia. We demonstrated that the kinetics of increased production of (.)NO in endotoxaemic organs, with the notable exception of the eye, do not follow the known pattern of NOS-2 induction under those conditions. Accordingly, only in early endotoxaemia a high level of (.)NO is detected, while in late endotoxaemia (.)NO detectability is diminished most probably due to concomitant oxidant stress.     

Fine needle aspiration appearance of extragastrointestinal stromal tumor. A case report

BACKGROUND: Gastrointestinal stromal tumors (GISTs) rarely develop outside the digestive tract and in the soft tissues of abdomen and retroperitoneum. Such tumors are designated extra-GISTs (EGISTs). Cytologic and immunocytochemical features of a case of EGIST are reported. CASE: A 54-year-old woman presented with a peritoneal mass, diameter 22 cm, adherent to the omentum and without a connection to the digestive tract. Fine needle aspiration biopsy (FNAB) of the excised tumor showed high cellularity in two patterns: monotonous spindle cells were intermingled with a mildly atypical epithelioid component. Immunocytochemistry performed on cytospins revealed reactivity for c-kit (CD117), CD34 and smooth muscle actin and negativity for S-100. The findings were concordant with a histologic diagnosis of EGIST. CONCLUSION: EGISTs are infrequent neoplasms and can be diagnosed in FNAB samples. The clinical/radiologic setting must be considered together with the cytologic features. Immunocytochemistry is a clue to the diagnosis when it detects c-kit reactivity.     

Characterization of the specificity of arginine-specific gingipains from Porphyromonas gingivalis reveals active site differences between different forms of the enzymes

Porphyromonas gingivalis is a pathogen associated with periodontal disease, and arginine-specific proteases (gingipains-R) from the bacterium are important virulence factors. The specificity of two forms of gingipain-R, HRgpA and RgpB, for substrate positions C-terminal to the cleavage site was analyzed, and notable differences were observed between the enzymes. Molecular modeling of the HRgpA catalytic domain, based on the structure of RgpB, revealed that there are four amino acid substitutions around the active site of HRgpA relative to RgpB that may explain their different specificity. Previously, differences in the ability of these two gingipain-R forms to cleave a number of proteins were attributed to additional adhesins on HRgpA mediating increased interaction with the substrates. Here, purified RgpA(cat), the catalytic domain of HRgpA, which like RgpB also lacks adhesin subunits, was used to show that the differences between HRgpA and RgpB are probably due to the amino acid substitutions at the active site. The kinetics of cleavage of fibrinogen, a typical protein substrate for the gingipain-R enzymes, which is bound by HRgpA but not RgpA(cat) or RgpB, were evaluated, and it was shown that there was no difference in the cleavage of the fibrinogen Aalpha-chain between the different enzyme forms. HRgpA degraded the fibrinogen Bbeta-chain more efficiently, generating distinct cleavage products. This indicates that while the adhesin domain(s) play(s) a minor role in the cleavage of protein substrates, the major effect is still provided by the amino acid substitutions at the active site of rgpA gene products versus those of the rgpB gene.     

Identification of UNC119 as a novel activator of SRC-type tyrosine kinases

Lyn, an Src-type tyrosine kinase, is associated with the interleukin (IL)-5 receptor in eosinophils. The mechanism of its activation is unknown. Through yeast two-hybrid screening we have cloned and characterized a new signaling molecule, Unc119, that associates with IL-5Ralpha and Src family tyrosine kinases. Unc119 induces the catalytic activity of these kinases through interaction with Src homology 2 and 3 domains. IL-5 stimulation of eosinophils increases Unc119 association with Lyn and induces its catalytic activity. Lyn is important for eosinophil survival. Eosinophils that are transduced with Unc119 have increased Lyn activity and demonstrate prolonged survival in the absence of IL-5. Inhibition of Unc119 down-regulates eosinophil survival. To our knowledge Unc119 is the first receptor-associated activator of Src family tyrosine kinases.     

Heterodimerization of substance P and mu-opioid receptors regulates receptor trafficking and resensitization

The micro-opioid receptor (MOR1) and the substance P receptor (NK1) coexist and functionally interact in nociceptive brain regions; however, a molecular basis for this interaction has not been established. Using coimmunoprecipitation and bioluminescence resonance energy transfer (BRET), we show that MOR1 and NK1 can form heterodimers in HEK 293 cells coexpressing the two receptors. Although NK1-MOR1 heterodimerization did not substantially change the ligand binding and signaling properties of these receptors, it dramatically altered their internalization and resensitization profile. Exposure of the NK1-MOR1 heterodimer to the MOR1-selective ligand [D-Ala2,Me-Phe4,Gly5-ol]enkephalin (DAMGO) promoted cross-phosphorylation and cointernalization of the NK1 receptor. Conversely, exposure of the NK1-MOR1 heterodimer to the NK1-selective ligand substance P (SP) promoted cross-phosphorylation and cointernalization of the MOR1 receptor. In cells expressing MOR1 alone, beta-arrestin directs the receptors to clathrin-coated pits, but does not internalize with the receptor. In cells expressing NK1 alone, beta-arrestin internalizes with the receptor into endosomes. Interestingly, in cells coexpressing MOR1 and NK1 both DAMGO and SP induced the recruitment of beta-arrestin to the plasma membrane and cointernalization of NK1-MOR1 heterodimers with beta-arrestin into the same endosomal compartment. Consequently, resensitization of MOR1-dependent receptor functions was severely delayed in coexpressing cells as compared with cells expressing MOR1 alone. Together, our findings indicate that MOR1 by virtue of its physical interaction with NK1 is sequestered via an endocytotic pathway with delayed recycling and resensitization kinetics.