Mechanisms of non-adrenergic non-cholinergic synaptic transmission in smooth muscle cells of the gastrointestinal tract

Non-adrenergic non-cholinergic (NANCh) inhibitory synaptic potentials in smooth muscle cells (SMC) of the gastrointestinal tract are of a complex transmitter and ion nature. A blocker of ATP receptors, suramin, blocks the fast component, while a blocker of NO synthase, L-NOARG, blocks the slow component of NANCh inhibitory synaptic potentials. In the presence of both suramin and L-NOARG, SMC respond to stimulation of the intramural plexus by generating a low-amplitude hyperpolarization, and VIP is likely to be the transmitter for this effect. Low-conductance Ca²⁺-dependent potassium channels are involved in generation of the fast component of NANCh inhibitory synaptic potentials, and these channels are effectively blocked by apamin. The slow component of this potential is generated by high-conductance Ca²⁺-dependent potassium channels. In the presene of both apamin and L-NOARG (or charibdotoxin), SMC respond to intramural stimulations with non-cholinergic excitatory synaptic potentials, and ATP application evokes depolarization. Both effects are blocked by suramin. In the presence of apamin, noradrenaline also evokes depolarization in SMC, and this effect, similarly to hyperpolarization under normal conditions, is blocked by phentolamine. Our studies allow us to suggest that in smooth muscles of the gastrointestinal tract there are two types of synaptic transmission: the excitatory cholinergic, adrenergic, and ATP-ergic transmission and the inhibitory adrenergic, ATP-ergic, NO-ergic, and VIP-ergic transmission.     

Effects of cyclopenta[c]phenanthrene and its derivatives on zona radiata protein, ERalpha, and CYP1A mRNA expression in liver of rainbow trout (Oncorhynchus mykiss Walbaum)

Despite cyclopenta-fused polycyclic aromatic hydrocarbons (CP-PAHs) have been detected in the environment, the ability of CP-PAH to induce cellular and tissue responses remains poorly characterized. In this study, xenoestrogen-associated responses (mRNA levels of estrogen receptor alpha, ERalpha, and zona radiata protein, Zrp) and xenobiotic effects (CYP1A mRNA) have been investigated in liver of juvenile rainbow trout after short-term treatment (8 and 24 h) with following compounds administered singly: cyclopenta[c]phenanthrene (CP[c]Ph); its derivatives, 5A-CP[c]Ph; 5A6M-CP[c]Ph; 5A9M-CP[c]Ph; B[c]Ph, a structurally similar polycyclic aromatic hydrocarbon; B[a]P, a model CYP1A inducer; and zearalenone (ZEA), naturally occurring ligand for ER. The CYP1A mRNA expression after 24 h of exposure with CP[c]Ph or its derivatives, except 5A9M-CP[c]Ph, was 3-9-fold higher compared to controls (P<0.05), but it was less than that caused by B[a]P (65-fold up regulation; P<0.01). Moreover, neither of the CP-PAH compounds modulated liver ERalpha or Zrp mRNA levels as compared to effects associated with ZEA. Interestingly, a treatment with this ER-ligand, caused moderate but significant increase of CYP1A mRNA expression (about 2.5-fold; P<0.05). The finding that ZEA is capable of acting as either estrogenic and xenobiotic compound, should be further explored in a more detailed and differently designed experiment.     

Influence of restoration on arbuscular mycorrhiza of Biscutella laevigata L. (Brassicaceae) and Plantago lanceolata L. (Plantaginaceae) from calamine spoil mounds

The arbuscular mycorrhizal status of two plant species, Biscutella laevigata L. and Plantago lanceolata L., was investigated on calamine spoil mounds in Boles?aw (southern Poland). Although B. laevigata is a member of the Brassicaceae, a family generally accepted as non-mycorrhizal, this species formed AM symbioses on both heavy metal-contaminated and non-contaminated sites. Besides vesicles and coils, arbuscules were also observed, especially in roots collected prior to seed maturity. Relative mycorrhizal root length and relative arbuscular richness were usually much higher in P. lanceolata than in B. laevigata but not absolute arbuscule richness. Roots of P. lanceolata showed higher colonisation than B. laevigata. Although roots were collected from plants in close proximity, no correlation in mycorrhizal parameters was found between the two species.     

Toxoplasma gondii: in vivo expression of BAG-5 and cyst formation is independent of TNF p55 receptor and inducible nitric oxide synthase functions

Wild type, TNFRp55(-/-), iNOS(-/-) and IFN-gamma(-/-) mice were infected with Toxoplasma gondii strain ME-49, and the central nervous system (CNS), lungs, liver, spleen, heart and kidneys were examined for the presence of parasites expressing tachyzoite-specific (SAG-1) and bradyzoite-specific (BAG-5) antigens. During the acute phase of infection, the peripheral organs, but not the CNS, of the IFN-gamma(-/-) mice are heavily parasitized by tachyzoites and there are no signs of parasites expressing BAG-5. In contrast, the tissues from TNFRp55(-/-) and inducible nitric oxide synthase (iNOS)(-/-) mice, mainly the CNS, presented high numbers of parasites expressing SAG-1 and/or BAG-5. Tachyzoite transformation into bradyzoite and cyst development was shown to be normal in the tissues from TNFRp55(-/-) and iNOS(-/-) mice, as indicated by the high numbers of BAG-5/PAS positive cysts. Consistently, reactivation of infection in IFN-gamma(-/-) mice was rapid and characterized by a dramatic increase in SAG-1, contrasting with slow course in the TNFRp55(-/-) or iNOS(-/-) mice associated with a relatively small increase in SAG-1- and/or BAG-5-positive parasites. In conclusion, our results suggest that the control of multiplication of tachyzoites is largely dependent on endogenous IFN-gamma with partial involvement of TNFRp55 and iNOS. In contrast, induction of BAG-5 expression and cyst formation during toxoplasmosis seems to be dependent on IFN-gamma, but independent of TNFRp55 and iNOS functions.     

Influence of the curvature on the water structure in the headgroup region of phospholipid bilayer studied by the solvent relaxation technique

Solvent relaxation (SR) in 1,2-dioleoyl-palmitoyl-sn-glycero-3-phosphocholine (DOPC) unilamellar vesicles of different size was probed by 6-hexadecanoyl-2-(((2-(trimethylammonium)ethyl)methyl)amino)naphthalene chloride (Patman), 6-propionyl-2-dimethylaminonaphthalene (Prodan) and 4-[(n-dodecylthio)methyl]-7-(N,N-dimethylamino)-coumarin (DTMAC). Patman probes the amount and mobility of the bound water molecules located at the carbonyl region of the bilayer. Membrane curvature significantly accelerates the solvent relaxation process, but does not influence the total Stokes shift, showing that membrane curvature increases the mobility, without affecting the amount of water molecules present in the headgroup region. This pattern was also verified for other phosphatidylcholines. Prodan is located in the phosphate region of the bilayer and probes a more polar, mobile and heterogeneous environment than Patman. The influence of membrane curvature on SR probed by Prodan is similar, however, less pronounced compared to Patman. DTMAC (first time used in SR) shows a broad distribution of locations along the z-axis. A substantial amount of the coumarin chromophores face bulk water. No effect of curvature on SR probed by DTMAC is detectable.     

A potential double role of anti-Lewis X antibodies in Helicobacter pylori-associated gastroduodenal diseases

In this study, we found Lewis X (Le(x)) determinants on 68% of Helicobacter pylori isolates from patients with chronic gastroduodenal diseases. Anti-Le(x) IgG were detected more frequently in the sera from dyspeptic children and adults (45 and 46%), with or without proved (culture) H. pylori infection, than in the sera from healthy individuals (14% and 25%). In contrast, the prevalence of anti-Le(x) IgM was higher in the groups of healthy individuals than in the groups of dyspeptic patients. Moreover, anti-Le(x) monoclonal antibody of IgM class enhanced the uptake of Le(x)(+) but not Le(x)(-) H. pylori isolates by phagocytes. In the sera from some dyspeptic patients, we detected Le(x)-anti-Le(x) IgG immune complexes (Le(x) ICs). There was a great difference between children and adults as regards the presence of Le(x) ICs. The immune complexes were found in the sera from nine out of 29 (27%) H. pylori-infected and three out of eight (37%) uninfected adult dyspeptic patients. In comparison, Le(x)-anti-Le(x) IgG ICs were detected only for two out of 18 (11%) H. pylori-infected children. Le(x) ICs were not found in the sera from healthy individuals. Our results suggest that anti-Le(x) IgM may play a protective role in H. pylori infections. In contrast, anti-Le(x) IgG and particularly Le(x)-anti-Le(x) IgG ICs might contribute to the pathogenesis of chronic H. pylori infections.     

Naturally occurring V1-env region variants mediate simian immunodeficiency virus SIVmac escape from high-titer neutralizing antibodies induced by a protective subunit vaccine

Macaques which developed high-titer neutralizing antibodies (htNAb) after immunization with a virion-derived oligomeric envelope glycoprotein subunit vaccine were protected against a homologous simian immunodeficiency virus SIVmac challenge. Here we demonstrate that the htNAb could be overcome by V1-env region variants isolated ex vivo from an SIVmac-infected macaque. The results further suggest that the development of V1-env region neutralization escape mutants is also necessary for survival of the virus in infected macaques. The immunological capacity of a single variable region to induce neutralizing antibodies in vaccinated and infected macaques initiate new ideas for a successful vaccine strategy.