Effects of pectin-induced passive linkage of gastric H on the gastric acid secretion and on the development of ethanol- and salicylate-induced gastric mucosal lesions in rats

The aim of this study was to evaluate the effects of intragastrically given pectin-induced physicochemical properties and actions on active gastric acid secretion and on the development of ethanol- and aspirin-induced gastric mucosal lesions. The observations were carried out on CFY-strain rats, fasted for 24 h before the experiments with water ad libitum. The observations were carried out in two experimental series. A) The gastric mucosal lesions were produced by intragastrically given 96% ethanol or aspirin prepared with 0.2 M HCl. Different doses of pectin (100, 50 and 25 mg.kg^–1, respectively) were administered intragastrically 30 min before giving necrotizing agents. The number of gastric lesions was noted 1 h after the administration, while the severity of gastric mucosal lesions was scored by semi-quantitative scale. B) The effects of pectin were studied on the volume and H⁺ secretion of the stomach in 4-h pylorus-ligated rats. It has been found that: 1) the gastric mucosal lesions could be produced in 100% of rats by the application of both necrotizing agents. 2) Pectin in doses of 50–100 mg.kg^–1 increased the number of gastric mucosal lesions in both models, while no increase was produced by the application of 25-mg.kg^–1 dose. 3) The severity of mucosal lesions increased significantly after the administration of all doses of pectin. 4) The pectin-induced increase of gastric lesions (number) showed a dose-response effect. 5) The pectin produced a significant increase in the volume of gastric secretion and gastric H⁺ secretion. It has been concluded that: a) pectin-induced physicochemical changes are able to enhance the aggression to gastric mucosa produced by ethanol and aspirin; b) a positive correlation exists between the linkage of H⁺ to pectin and significant active metabolic response in the rat stomach; c) pectin alone stimulates the active metabolic process of the gastric H⁺ secretion.     

Ghrelin amplifies the nicotine-induced dopamine release in the rat striatum

The orexigenic peptide ghrelin plays a prominent role in the regulation of energy balance and in the mediation of reward mechanisms and reinforcement for addictive drugs, such as nicotine. Nicotine is the principal psychoactive component in tobacco, which is responsible for addiction and relapse of smokers. Nicotine activates the mesencephalic dopaminergic neurons via nicotinic acetylcholine receptors (nAchR). Ghrelin stimulates the dopaminergic neurons via growth hormone secretagogue receptors (GHS-R1A) in the ventral tegmental area and the substantia nigra pars compacta resulting in the release of dopamine in the ventral and dorsal striatum, respectively. In the present study an in vitro superfusion of rat striatal slices was performed, in order to investigate the direct action of ghrelin on the striatal dopamine release and the interaction of ghrelin with nicotine through this neurotransmitter release. Ghrelin increased significantly the dopamine release from the rat striatum following electrical stimulation. This stimulatory effect was reversed by both the selective nAchR antagonist mecamylamine and the selective GHS-R1A antagonist GHRP-6. Nicotine also increased significantly the dopamine release under the same conditions. This stimulatory effect was antagonized by mecamylamine, but not by GHRP-6. Ghrelin further stimulated the nicotine-induced dopamine release and this effect was abolished by mecamylamine and was partially inhibited by GHRP-6. The present results demonstrate that ghrelin stimulates directly the dopamine release and amplifies the nicotine-induced dopamine release in the rat striatum. We presume that striatal cholinergic interneurons also express GHS-R1A, through which ghrelin can amplify the nicotine-induced dopamine release in the striatum. This study provides further evidence of the impact of ghrelin on the mesolimbic and nigrostriatal dopaminergic pathways. It also suggests that ghrelin signaling may serve as a novel pharmacological target for treatment of addictive and neurodegenerative disorders.     

Characterization of calretinin I-II as an EF-hand, Ca2+, H+-sensing domain

Calretinin, a neuronal protein with well-defined calcium-binding properties, has a poorly defined function. The pH dependent properties of calretinin (CR), the N-terminal (CR I-II), and C-terminal (CR III-VI) domains were investigated. A drop in pH within the intracellular range (from pH 7.5 to pH 6.5) leads to an increased hydrophobicity of calcium-bound CR and its domains as reported by fluorescence spectroscopy with the hydrophobic probe 2-(p-toluidino)-6-naphthalenesulfonic acid (TNS). The TNS data for the N- and C-terminal domains of CR are additive, providing further support for their independence within the full-length protein. Our work concentrated on CR I-II, which was found to have hydrophobic properties similar to calmodulin at lower pH. The elution of CR I-II from a phenyl-Sepharose column was consistent with the TNS data. The pH-dependent structural changes were further localized to residues 13-28 and 44-51 using nuclear magnetic resonance spectroscopy chemical shift analysis, and there appear to be no large changes in secondary structure. Protonation of His 12 and/or His 27 side chains, coupled with calcium chelation, appears to lead to the organization of a hydrophobic pocket in the N-terminal domain. CR may sense and respond to calcium, proton, and other signals, contributing to conflicting data on the proteins role as a calcium sensor or calcium buffer.     

Long persistence of importin-beta explains extended survival of cells and zygotes that lack the encoding gene

Importin-beta is an essential component of nuclear protein import, spindle formation and nuclear envelope assembly. Formerly, the function of the Drosophila Ketel gene, which encodes importin-beta and is essential for the survival to adulthood, seemed to be required only in the mitotically active cells. We report here that importin-beta function is required in every cell and that this protein possesses an exceptionally long life span. Mosaic analysis, using gynanders, indicated that zygotic function of the Ketel gene is essential in a large group of cells in the embryos. Expression of a UAS-Ketel transgene by different tissue specific Gal4 drivers on ketel(null)/- hemizygous background revealed the requirement of Ketel gene function in the ectoderm. Elimination of the Ketel gene function using a UAS-Ketel-RNAi transgene driven by different Gal4 drivers confirmed the indispensability of the Ketel gene in the ectoderm. Using GFP-tagged importin-beta (encoded by a ketel(GFP) allele) we revealed that the maternally provided GFP-importin-beta molecules persist up to larval life. The zygotic Ketel gene is expressed in every cell during early gastrulation. Although the gene is then turned off in the non-dividing cells, the produced importin-beta molecules persist long and carry out nuclear protein import throughout the subsequent stages of development. In the continuously dividing diploid cells, the Ketel gene is constitutively expressed to fulfill all three functions of importin-beta.     

Large granular lymphocytes,Leu 7 reactivity and natural killer cell function in peripheral blood of patients with Hodgkin's disease

Summary The percentage and absolute number of lymphocytes and Leu 7⁺ cells were significantly lower in HD even in active stages. There was no significant difference in the percentage of LGL between the three groups (control, active HD, inactive HD), however, because of differences in counts of lymphocytes the absolute number of LGL was significantly lower in HD even in the active group than that in healthy controls. The absolute count of LGL and Leu 7⁺ cells in patients in remission was significantly higher than that in active HD. Natural cytotoxicity against K-562 cells was also significantly lower in active patients in comparison with controls, while the percentage of cytotoxicity was slightly but not significantly higher in patients in remission than that in the active group. A positive correlation was observed between all the three examined parameters both in controls and in patients with active and inactive HD.     

Floristic composition and conservation value of the stubble-field weed community,dominated by <Emphasis Type="Italic">Stachys annua</Emphasis> in western Hungary

The stubble-field weed community, dominated by Stachys annua, was generally distributed in Hungary until the 1950s on mid-heavy and heavy, base-rich soils. Stachys annua is an excellent nectar-producer, and from the nectar collected in its habitats popular stubble-honey was produced. This vegetation type has suffered significant decline, mainly due to the early ploughing of stubbles associated with the intensification of agriculture. In the present study, the floristic composition of this community is assessed based on 213 phytosociological records, and its distribution in the past ten years in western Hungary is mapped. Sixty-five percent of the species are of Eurasian, European and Mediterranean elements, and the largest proportion of the species are spring-germinating summer annuals. The proportion of insect-pollinated plant species is approximately 70%, and the species composition also offers significant seed food sources for farmland birds, e.g. Coturnix coturnix and Perdix perdix. Therefore this community should deserve a high conservation priority for biodiversity. The factors that offer the greatest threats to the continuing existence of this community type are intensive agricultural management and the increasing spread of Ambrosia artemisiifolia.     

What You See Is What You Get? Exclusion Performances in Ravens and Keas

Background

Among birds, corvids and parrots are prime candidates for advanced cognitive abilities. Still, hardly anything is known about cognitive similarities and dissimilarities between them. Recently, exclusion has gained increasing interest in comparative cognition. To select the correct option in an exclusion task, one option has to be rejected (or excluded) and the correct option may be inferred, which raises the possibility that causal understanding is involved. However, little is yet known about its evolutionary history, as only few species, and mainly mammals, have been studied.

Methodology/Principal Findings

We tested ravens and keas in a choice task requiring the search for food in two differently shaped tubes. We provided the birds with partial information about the content of one of the two tubes and asked whether they could use this information to infer the location of the hidden food and adjust their searching behaviour accordingly. Additionally, this setup allowed us to investigate whether the birds would appreciate the impact of the shape of the tubes on the visibility of food. The keas chose the baited tube more often than the ravens. However, the ravens applied the more efficient strategy, choosing by exclusion more frequently than the keas. An additional experiment confirmed this, indicating that ravens and keas either differ in their cognitive skills or that they apply them differently.

Conclusion

To our knowledge, this is the first study to demonstrate that corvids and parrots may perform differently in cognitive tasks, highlighting the potential impact of different selection pressures on the cognitive evolution of these large-brained birds.     

Synthesis and evaluation of 5-HT(2A) and 5-HT(2C) receptor binding affinities of novel pyrimidine derivatives

In an effort to find potential anxiolytic and/or antipsychotic agents with selective 5-HT(2C) affinity a series of new pyrimidine derivatives was prepared and the binding affinities for 5-HT(2A) and 5-HT(2C) receptors were determined.     

Involvement of Neurotransmitters in the Action of the Nociceptin/Orphanin FQ Peptide-Receptor System on Passive Avoidance Learning in Rats

The nociceptin/orphanin FQ peptide (NOP) receptor and its endogenous ligand plays role in several physiologic functions of the central nervous system, including pain, locomotion, anxiety and depression, reward and drug addiction, learning and memory. Previous studies demonstrated that the NOP-receptor system induces impairment in memory and learning. However, we have little evidence about the underlying neuromodulation. The aim of the present study was to investigate the involvement of distinct neurotransmitters in the action of the selective NOP receptor agonist orphan G protein-coupled receptor (GPCR) SP9155 P550 on memory consolidation in a passive avoidance learning test in rats. Accordingly, rats were pretreated with a nonselective muscarinic acetylcholine receptor antagonist, atropine, a γ-aminobutyric acid subunit A (GABA-A) receptor antagonist, bicuculline, a D2, D3, D4 dopamine receptor antagonist, haloperidol, a nonselective opioid receptor antagonist, naloxone, a non-specific nitric oxide synthase inhibitor, nitro-l-arginine, a nonselective α-adrenergic receptor antagonist, phenoxybenzamine and a β-adrenergic receptor antagonist, propranolol. Atropine, bicuculline, naloxone and phenoxybenzamine reversed the orphan GPCR SP9155 P550-induced memory impairment, whereas propranolol, haloperidol and nitro-l-arginine were ineffective. Our results suggest that the NOP system-induced impairment of memory consolidation is mediated through muscarinic cholinergic, GABA-A-ergic, opioid and α-adrenergic receptors, whereas β-adrenergic, D2, D3, D4-dopaminergic and nitrergic mechanisms are not be implicated.