Selective inhibition of MAO-A,not MAO-B,results in antidepressant-like effects on DRL 72-s behavior

The effects of monoamine oxidase inhibitors (MAOIs) that selectively inhibit the MAO-A or MAO-B forms of MAO were studied in rats performing under a differential-reinforcement-of-low-rate 72-s (DRL 72-s) schedule of reinforcement. Clorgyline and CGP11305A, irreversible and reversible MAO-A inhibitors, respectively, increased the reinforcement rate, decreased the response rate, and enhanced temporal discrimination. The irreversible MAO-B inhibitor (–)-deprenyl did not produce similar effects. Pargyline did not increase the reinforcement rate at low doses that selectively inhibit MAO-B, but did increase the reinforcement rate at doses that inhibit MAO-A by more than 90%. The present results are in accord with clinical data demonstrating that MAO-A inhibitors are effective therapeutic agents in treating depression while MAO-B inhibitors are of questionable antidepressant efficacy. The present findings provide further evidence that the DRL 72-s schedule may be useful both as a screen for identifying new antidepressants and for investigating the neurochemical effects of antidepressant drugs that are responsible for their therapeutic effects.     

Anion channels in a leaky epithelium

We have used the patch-clamp technique to characterize three anion channels in the ventricular membrane of the choroid plexus epithelium from Necturus. The most frequently occurring channel had a nonlinear IV-curve. The conductance in excised patches with 112 mM chloride at both sides was 28 pS at 0 mV, increasing towards positive membrane potentials. The selectivity ratios were P _NaP _Cl 0.1 and . SITS and furosemide (1 mM) on the inside reduces chloride flux to 0.15 and 0.37 times the control value. In attached patches, the most commonly observed channel had a conductance of 7.5 pS. The single-channel current for this channel reversed direction at 15 mV hyperpolarization, indicating accumulation of chloride to a factor of 1.8 above equilibrium. External stimulation of the tissue by theophylline, IBMX and dbcAMP, or by hypotonic shock did not increase the activity of this channel. In very few excised patches, we have observed a chloride channel with a conductance of 7 pS with 112 mM chloride at both sides. The 7 pS channel appears to be identical to a 2 pS channel found in attached patches. The 2 pS channel was not normally active in attached patches but was activated in 28% of the patches by external stimulation. Finally, in few excised patches we have found a 375 pS channel which inactivates within seconds when membrane potential is stepped from 0 mV to a value that differs more than 10–20 mV from zero. The channel did not conduct gluconate but and P _NaP _Cl 0.1. Internal SITS and furosemide (1 mM) reduced chloride flux to 0.3 and 0.5 times the control value. The channel was never seen in attached patches. The current carried through these channels can not account for the transepithelial steady state Cl^–-flux measured by microelectrodes. KCl exit from the cell is suggested to be carried by KCl-cotransport or by channels that are too small to be seen in patch-clamp experiments.     

Borrelia burgdorferi sensu stricto in yellow-necked mice and feeding Ixodes ricinus ticks in a forest habitat of west central Poland

Wild rodents and the subadult Ixodes ricinus (L.) ticks infesting them were examined for the presence of Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner s.l. in a sylvatic habitat in west central Poland during May-September 2002. In total, 818 feeding ticks were recovered from 73 infested yellow-necked mice, Apodemus flavicollis Melchior; in addition, bank voles, Clethrionomys glareolus Schreber, were rarely captured and proved to be weakly parasitized. Only 2.7% of A. flavicollis and 2.2% of 320 engorging larvae were polymerase chain reaction (PCR) positive for the bacterium. All spirochete-PCR-positive samples yielded exclusively B. burgdorferi s.s. This genospecies was also the most prevalent in questing nymphs and accounted for 87.5% of the total number of Borrelia infections in nymphal ticks collected during May and June 2 yr later. The presence of the same genospecies both in naturally engorged larvae and blood-positive animals as well as the high predominance of B. burgdorferi s.s. in questing nymphs strongly differs from most study sites investigated in Europe. This unique pattern of Borrelia-diversity in both rodents and ticks seems to be determined by highly site-specific host vertebrate cenosis, and yellow-necked mice are involved in the maintenance of B. burgdorferi s.s. in the forest habitat. However, the transmission efficiency of this spirochete from the mice to the I. ricinus vector seems to be very low. The research provides additional information on the complexity of B. burgdorferi s.l. ecology in Europe, pointing to the importance of the local host community.     

Effects of chemical mediators of anaphylaxis on ciliary function

We assessed the effects of selected chemical mediators of anaphylaxis on CBF in vitro. Ciliated epithelial cells were obtained from the trachea of conscious sheep with a cytology brush and suspended in a perfusion chamber containing KH. Ciliary activity was viewed microscopically and recorded on videotape for subsequent slow-motion analysis of CBF. Prostaglandin E1 (10(-8) M to 10(-6) M), prostaglandin E2 (10(-10) M to 10(-6) M), and leukotriene-C4 (10(-8) M) increased CBF between 7% and 33%. Histamine caused ciliostimulation only at the relatively high concentrations above 10(-5) M (7% increase in CBF), whereas prostaglandin F2 alpha (10(-10) M and 10(-6) M) was without effect. In no preparation was ciliary discoordination observed. These findings indicate that several chemical mediators of anaphylaxis stimulate CBF and that the previously described impairment of mucociliary transport in stable allergic asthma or antigen-induced bronchoconstriction is probably not caused by a primary alteration of ciliary function.     

Chicks from a high and low feather pecking line of laying hens differ in apomorphine sensitivity

Proactive rodents show a larger behavioral response to apomorphine (APO) than reactive copers, suggesting a more sensitive DA system in proactive individuals. Previously, chicks from a high feather pecking (HFP) and low feather pecking line (LFP) have been suggested to display a proactive and reactive coping strategy, respectively. Therefore, at approximately 4 weeks of age, the behavior of 48 LFP and 48 HFP chicks in response to an APO injection was studied using an open field. Another objective of the present study was to determine whether behavioral variation (in an open field) between HFP and LFP birds, after APO injection, is also reflected by variation of D(1) and D(2) receptor densities in the brain. Receptor binding capacities were assessed by measuring specific binding of tritiated D(1) and D(2) receptor ligands in different regions of the brain of control HFP and LFP chicks. In the present study, it is shown that indeed HFP chicks display a more enhanced behavioral response to acute APO treatment (0.5 mg/kg BW) than LFP birds in an open field. This difference was not reflected by variation of D(1) and D(2) receptor densities in the brain between both lines.     

The cellular uptake of sensitizers bound to cyclodextrin carriers

Photodynamic therapy of cancer uses the interaction of sensitizers and light to destroy cancer cells. In this study we tested the cellular uptake of meso-tetrakis(4-sulfonatophenyl)porphine (TPPS4) and its complex PdTPPS4 in the presence or absence of 2-hydroxypropyl-cyclodextrins (hpCDs) on G361 human melanoma cells. Self-fluorescence in G361 cells were measured by Perkin-Elmer LS50B luminometer equipped with well plate reader accessory. Morphological changes in cells have been evaluated using inversion fluorescent microscope Olympus IX 70 and image analysis. The uptake of the sensitizer PdTPPS4 at the given time interval from 1 to 48 hours is markedly higher than the uptake of TPPS4. The highest uptake was found for sensitizer PdTPPS4 in combination with hpbetaCD. TPPS4 and PdTPPS4 especially in the supramolecular complex with nontoxic cyclodextrin carriers represent efficient sensitizers for photodynamic therapy in vitro on G361 cells.     

Microorganisms isolated from clinical specimens of patients from the Department of Thoracic Surgery

The clinical specimens received from patients hospitalized in Department of Thoracic Surgery between 1997 and 2001 were microbiologically examined. The main specimen for microbiological examination was pleural fluid (median 34%). The frequency of specimens from bronchial tree increased significantly (from 4% to 26%) with concurrent decrease of sputum (from 29% to 6%). Among isolated pathogens, Gram negative rods were the most frequent (median 48%) and Pseudomonas sp. was the main pathogen among them. Occurrence of staphylococci was median 22% and Staphylococcus aureus, with a little decrease in analyzed period, was still the main Gram positive pathogen. Simultaneously the occurrence of MRSA in the last three years dropped three times. The number of isolations of yeasts have risen from 5.8% to 10.3%.     

Anionic block polymerization of β-lactones initiated by potassium solutions, 1. Synthesis of poly(4-methyl-2-oxetanone-block-2-oxetanone)

The block polymerization of 4-methyl-2-oxetanone (β-butyrolactone) with 2-oxetanone (β-propiolactone) proceeds fast with a yield of more than 90%, in the presence of potassium solutions in THF containing 18-crown-6. Poly(4-methyl-2-oxetanone-block-2-oxetanone) polymers having the expected molecular weight and composition are formed by this way. Their glass transition and melting temperatures as well as their melting enthalpies, determined by DSC, show a strict correlation with block polymer composition.