Multiple treatment potentiates the anticonvulsive activity of cholecystokinin octapeptides

The dose-response curves for the anticonvulsive activity of sulfated and nonsulfated cholecystokinin octapeptide (CCK-8-SE and CCK-8-NS) against picrotoxin-induced (6 mg/kg SC) seizures were assessed either following or without pretreatment with a single high dose of CCK-8-SE or CCK-8-NS, to examine acute tolerance to the effect after IP injections in mice. As CCK-8-SE or CCK-8-NS pretreatment, a 1.6 μmole/kg dose was injected 2 hr prior to the second injection. No acute tolerance to the anticonvulsive activity was demonstrated, and CCK-8-NS pretreatment significantly potentiated its own anticonvulsive activity. Chronic (8-day) daily treatment with a 0.16 μmole/kg dose of CCK-8-SE or CCK-8-NS antagonized seizures by picrotoxin, presumably in a cumulative manner. To investigate the interactions of CCK octapeptides with other anticonvulsive agents, picrotoxin-induced seizures were antagonized with several doses of diazepam following or without acute, high-dose pretreatment with CCK-8-SE or CCK-8-NS. The two octapeptides only slightly modified the activity of diazepam: CCK-8-SE pretreatment displayed a tendency to antagonize it, while CCK-8-NS pretreatment to potentiate it. The results suggest that multiple treatment with CCK-8 induces sensitization of CCK receptors mediating anticonvulsive activity.     

Causes of vagrancy of North Asian passerines in western Europe

In recent decades, several explanations for vagrancy of North Asian bird species in Europe have been suggested. The explanations can typically be divided into two, non-exclusive groups. Some cite weather factors as the primary cause of vagrancy, whereas others hypothesize an internal defect behind the phenomenon. In addition, some authors also suggest climate-driven range expansion following breeding population increase as a contributing factor. In recent years, studies have been published that have provided clear evidence for the origin of vagrant birds, as well as the reasons for their vagrancy. Here we summarize current knowledge and conclude that weather, habitat use, feeding habit, breeding success and climate change are important factors that affect the vagrancy of birds, together with the number of observers playing an important role in contributing data. In the future, advances in technology such as the development of tracking systems and the extensive use of stable isotopes will make it possible to explain the causes of vagrancy more precisely, so further research in this area of ornithology is essential.     

Fumonisin B1-Induced Oxidative Burst Perturbed Photosynthetic Activity and Affected Antioxidant Enzymatic Response in Tomato Plants in Ethylene-Dependent Manner

Fumonisin B1 (FB1) is a harmful mycotoxin produced by Fusarium species, which results in oxidative stress leading to cell death in plants. FB1 perturbs the metabolism of sphingolipids and causes growth and yield reduction. This study was conducted to assess the role of ethylene in the production and metabolism of reactive oxygen species in the leaves of wild type (WT) and ethylene receptor mutant Never ripe (Nr) tomato and to elucidate the FB1-induced phytotoxic effects on the photosynthetic activity and antioxidant mechanisms triggered by FB1 stress. FB1 exposure resulted in significant ethylene emission in a concentration-dependent manner in both genotypes. Moreover, FB1 significantly affected the photosynthetic parameters of PSII and PSI and activated photoprotective mechanisms, such as non-photochemical quenching in both genotypes, especially under 10 µM FB1 concentration. Further, the net photosynthetic rate and stomatal conductance were significantly reduced in both genotypes in a FB1 dose-dependent manner. Interestingly, lipid peroxidation and loss of cell viability were also more pronounced in WT as compared to Nr leaves indicating the role of ethylene in cell death induction in the leaves. Thus, FB1-induced oxidative stress affected the working efficiency of PSI and PSII in both tomato genotypes. However, ethylene-dependent antioxidant enzymatic defense mechanisms were activated by FB1 and showed significantly elevated levels of superoxide dismutase (18.6%), ascorbate peroxidase (129.1%), and glutathione S-transferase activities (66.62%) in Nr mutants as compared to WT tomato plants confirming the role of ethylene in the regulation of cell death and defense mechanisms under the mycotoxin exposure.

     

Impact of electrolyte solution on electrochemical oxidation treatment of Escherichia coli K-12 by boron-doped diamond electrodes

We studied the disinfection efficacy of boron-doped electrodes on Escherichia coli-contaminated water-based solutions in three different electrolytes, physiological solution (NaCl), phosphate buffer (PB), and phosphate buffer saline (PBS). The effect of the electrochemical oxidation treatment on the bacteria viability was studied by drop and spread plate cultivation methods, and supported by optical density measurements. We have found that bacterial suspensions in NaCl and PBS underwent a total inactivation of all viable bacteria within 10 min of the electrochemical treatment. By contrast, experiments performed in the PB showed a relatively minor decrease of viability by two orders of magnitude after 2 h of the treatment, which is almost comparable with the untreated control. The enhanced bacterial inactivation was assigned to reactive chlorine species, capable of penetrating the bacterial cytoplasmic membrane and killing bacteria from within.     

Polyacetylenes from the rabbitbrush,Chrysothamnus nauseosus

Four new polyacetylenes, methyl Z,Z-10-acetoxymatricariate, methyl Z,Z-10-hydroxymatricariate, methyl 2(Z)-10-acetoxy-8,9-epoxydecen- 4,6-diynoate and methyl 2(Z)-10-hydroxy-8,9-epoxydecen-4,6-diynoate, were isolated from the composite Chrysothamnus nauseosus. These compounds are naturally-occurring antifeedants of the Colorado potato beetle. The assigned structures rest on their spectroscopic properties as well as chemical interconversions.     

Effects of α2 and 2′-5′-oligoadenylate on tetrodotoxin-sensitive sodium transport in neuroblastoma cellsand 2′-5′-oligoadenylate on tetrodotoxin-sensitive sodium transport in neuroblastoma cells

We investigated the actions of human recombinant α₂-interferon and a secondary messenger of its action, 2′-5′-oligoadenylate, on tetrodotoxin (TTX)-sensitive sodium transport using human (IMR-32) and murine (NIE-115) neuroblastoma cells. In biochemical experiments using²²Na, human interferon was shown to increase entry of²²Na into IMR-32 neuroblastoma cells through the channels activated by veratrine and scorpion toxin. This increase was clearly dose-dependent. Cell treatment with TTX completely inhibited this sodium transport. On the contrary, 2′-5′-oligoadenylate depressed entry of²²Na into neuroblastoma cells. The activation effect was not observed under the action of human α₂-interferon on TTX-sensitive sodium flows to the murine neuroblastoma cells, which demonstrated the species-related specificity of this agent.