Methoxy-Substituted Hydroxychalcone Reduces Biofilm Production,Adhesion and Surface Motility of Acinetobacter baumannii by Inhibiting ompA Gene Expression

An increasing lack of available therapeutic options against Acinetobacter baumannii urged researchers to seek alternative ways to fight this extremely resistant nosocomial pathogen. Targeting its virulence appears to be a promising strategy, as it offers considerably reduced selection of resistant mutants. In this study, we tested antibiofilm potential of four synthetic chalcone derivatives against A. baumannii. Compound that showed the greatest activity was selected for further evaluation of its antivirulence properties. Real-time PCR was used to evaluate mRNA expression of biofilm-associated virulence factor genes (ompA, bap, abaI) in treated A. baumannii strains. Also, we examined virulence properties related to the expression of these genes, such as fibronectin- and collagen-mediated adhesion, surface motility, and quorum-sensing activity. The results revealed that the expression of all tested genes is downregulated together with the reduction of adhesion and motility. The conclusion is that 2′-hydroxy-2-methoxychalcone exhibits antivirulence activity against A. baumannii by inhibiting the expression of ompA and bap genes, which is reflected in reduced biofilm formation, adhesion, and surface motility.     

Mutation in the Scyl1 gene encoding amino-terminal kinase-like protein causes a recessive form of spinocerebellar neurodegeneration

Here, we show that the murine neurodegenerative disease mdf (autosomal recessive mouse mutant 'muscle deficient') is caused by a loss-of-function mutation in Scyl1, disrupting the expression of N-terminal kinase-like protein, an evolutionarily conserved putative component of the nucleocytoplasmic transport machinery. Scyl1 is prominently expressed in neurons, and enriched at central nervous system synapses and neuromuscular junctions. We show that the pathology of mdf comprises cerebellar atrophy, Purkinje cell loss and optic nerve atrophy, and therefore defines a new animal model for neurodegenerative diseases with cerebellar involvement in humans.     

MK-801 effect on regional cerebral oxidative stress rate induced by different duration of global ischemia in gerbils

We investigated MK-801 effect on ischemia-induced oxidative stress—the most important factor that exacerbates brain damage by reperfusion. The common carotid arteries of gerbils were occluded for 5, 10, or 15 min. Immediately after the occlusion, MK-801 (3 mg/kg i.p.) or saline were given in normothermic conditions. The MK-801 effects were followed in vivo by monitoring the neurological status of animals and at the intracellular level by standard biochemical assays. We investigated nitric oxide levels, superoxide production, superoxide dismutase activity, index of lipid peroxidation (ILP), and reduced glutathione content in hippocampus, striatum, forebrain cortex, and cerebellum. The measurements took place at different times (1, 2, 4, 7, 14, and 28 days) after reperfusion. Increased duration of cerebral ischemia resulted in a progressive induction of oxidative stress. Our results revealed pattern of dynamic changes in each oxidative stress parameter level which corresponded with ischemia duration in all tested brain structures. Most sensitive oxidative stress parameters were ILP and superoxide production. Our study confirmed spatial distribution of ischemia-induced oxidative stress. Tested brain structures showed different sensitivity to each oxidative stress parameter. As judged by biochemical and neurological data, applied MK-801 showed neuroprotective efficiency by reduction of ischemia-induced oxidative stress in brain.     

Glandular trichomes and essential oil characteristics of in vitro propagated <Emphasis Type="Italic">Micromeria pulegium</Emphasis> (Rochel) Benth. (Lamiaceae)

Main conclusion

In vitro conditions and benzyladenine influenced both content and composition of micropropagated Micromeria pulegium essential oils, with pulegone and menthone being the main essential oil components. The content and chemical composition of Micromeria pulegium (Rochel) Benth. essential oils were studied in native plant material at vegetative stage and in micropropagated plants, obtained from nodal segments cultured on solid MS medium supplemented with N⁶–benzyladenine (BA) or kinetin at different concentrations, alone or in combination with indole-3-acetic acid. Shoot proliferation was achieved in all treatments, but the highest biomass production was obtained after treatment with 10 μM BA. Phytochemical analysis identified up to 21 compounds in the essential oils of wild-growing and in vitro cultivated plants, both showing very high percentages of total monoterpenoids dominated by oxygenated monoterpenes of the menthane type. Pulegone and menthone were the main essential oil components detected in both wild-growing plants (60.07 and 26.85 %, respectively) and micropropagated plants grown on either plant growth regulator-free medium (44.57 and 29.14 %, respectively) or BA-supplemented medium (50.77 and 14.45 %, respectively). The percentage of total sesquiterpenoids increased in vitro, particularly owing to sesquiterpene hydrocarbons that were not found in wild-growing plants. Differences in both content and the composition of the essential oils obtained from different samples indicated that in vitro culture conditions and plant growth regulators significantly influence the essential oils properties. In addition, the morphology and structure of M. pulegium glandular trichomes in relation to the secretory process were characterized for the first time using SEM and light microscopy, and their secretion was histochemically analyzed.

     

Tumor Growth Rate Determines the Timing of Optimal Chronomodulated Treatment Schedules

In host and cancer tissues, drug metabolism and susceptibility to drugs vary in a circadian (24 h) manner. In particular, the efficacy of a cell cycle specific (CCS) cytotoxic agent is affected by the daily modulation of cell cycle activity in the target tissues. Anti-cancer chronotherapy, in which treatments are administered at a particular time each day, aims at exploiting these biological rhythms to reduce toxicity and improve efficacy of the treatment. The circadian status, which is the timing of physiological and behavioral activity relative to daily environmental cues, largely determines the best timing of treatments. However, the influence of variations in tumor kinetics has not been considered in determining appropriate treatment schedules. We used a simple model for cell populations under chronomodulated treatment to identify which biological parameters are important for the successful design of a chronotherapy strategy. We show that the duration of the phase of the cell cycle targeted by the treatment and the cell proliferation rate are crucial in determining the best times to administer CCS drugs. Thus, optimal treatment times depend not only on the circadian status of the patient but also on the cell cycle kinetics of the tumor. Then, we developed a theoretical analysis of treatment outcome (TATO) to relate the circadian status and cell cycle kinetic parameters to the treatment outcomes. We show that the best and the worst CCS drug administration schedules are those with 24 h intervals, implying that 24 h chronomodulated treatments can be ineffective or even harmful if administered at wrong circadian times. We show that for certain tumors, administration times at intervals different from 24 h may reduce these risks without compromising overall efficacy.     

Sharing roosts but not ectoparasites: high host-specificity in bat flies and wing mites of Miniopterus schreibersii and Rhinolophus ferrumequinum (Mammalia: Chiroptera)

Schreiber’s bent-winged bat Miniopterus schreibersii and the greater horseshoe bat Rhinolophus ferrumequinum are widespread and common cavernicolous species across southern Europe that host numerous specialized ectoparasite species. The objective of this study was to characterize the species assemblage, genetic diversity, and host specificity of bat flies (Nycteribiidae, Diptera) and wing mites (Spinturnicidae, Acari) found on these bat hosts in Serbia and Bosnia and Herzegovina. Notably, while bat flies lay puparia on the cave walls and can thus be transmitted indirectly, wing mites require direct body contact for transmission. Morphological identification and sequencing of a 710-bp fragment of cytochrome oxidase I gene of 207 bat flies yielded 4 species, 3 on M. schreibersii and 1 on R. ferrumequinum. Sequencing of a 460-bp small subunit ribosomal RNA fragment, in all 190 collected wing mites revealed 2 species, 1 per host. In no case was a parasite associated with 1 host found on the other host. Species and genetic diversity of flies were higher in M. schreibersii, likely reflecting their host’s larger colony sizes and migratory potential. Mite species of both hosts showed similarly low diversity, likely due to their faster life history and lower winter survival. Our findings highlight a remarkably high host-specificity and segregation of ectoparasite species despite direct contact among their hosts in the roost, suggesting a defined host preference in the investigated ectoparasite species. Furthermore, the differences in ectoparasite genetic diversity exemplify the interplay between host and parasite life histories in shaping parasite population genetic structure.     

Free radical–scavenging activity and DNA damaging potential of auxins IAA and 2‐methyl‐IAA evaluated in human neutrophils by the alkaline comet assay

Auxins, of which indole‐3‐acetic acid (IAA) is the most widespread representative, are plant hormones. In addition to plants, IAA also naturally occurs in humans in micromolar concentrations. In the presence of peroxidase, indolic auxins are converted to cytotoxic oxidation products and have thus been proposed for use in gene‐directed enzyme/prodrug tumor therapy. Since data on the genotoxicity of IAA and its derivatives are not consistent, here we investigate the early DNA damaging effects (2‐h treatment) of the auxins, IAA, and 2‐methyl‐indole‐3‐acetic acid (2‐Me‐IAA) by the alkaline comet assay and compare them with their free radical–scavenging activity measured by the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) assay. Human neutrophils are chosen as the test system since they possess inherent peroxidase activity. The results of the comet assay indicate an increase in DNA damage in a dose‐dependent manner up to 1.00 mM of both auxins. Generally, IAA applied in the same concentration had greater potential to damage DNA in human neutrophils than did 2‐Me‐IAA. The genotoxicities of the two examined auxins are negatively correlated with their antioxidant activities, as measured by the DPPH assay; 2‐Me‐IAA showed a higher antioxidant capacity than did IAA. We assume that differences in the molecular structure of the tested auxins contributed to differences in their metabolism, in particular, with respect to interactions with peroxidases and other oxidative enzymes in neutrophils. However, the exact mechanisms have to be elucidated in future studies. © 2010 Wiley Periodicals, Inc. J Biochem Mol Toxicol 24:165–173, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jbt.20323     

The effects of acclimation and rearing conditions on the response of tropical and temperate populations ofDrosophila melanogaster andD. simulans to a temperature gradient (Diptera: Drosophilidae)

The effects of rearing and acclimation on the response of adultDrosophila to temperature were investigated in a gradient.D. melanogaster flies preferred a higher mean temperature and were distributed over a wider range of temperatures thanD. simulans flies. Acclimating adults at different temperatures for a week did not influence the response of either species. Adults reared at 28°C as immatures had a lower mean preference than those reared at cooler temperatures, suggesting that flies compensated for the effects of rearing conditions. Adults from tropical and temperate populations ofD. melanogaster andD. simulans did not differ in the mean temperature they preferred in a gradient, suggesting little genetic divergence for this trait within species. The species differences and environmental responses may be related to changes in optimal physiological conditions for the flies.     

Somatostatin-14 influences pituitary–ovarian axis in peripubertal rats

The effects of multiple somatostatin (SRIH-14) administration on the pituitary-ovarian axis were examined in peripubertal rats. Female Wistar rats received subcutaneously, two daily doses of 20 mug SRIH-14 per 100 g body weight (b.w.) for five consecutive days (from the 33rd to the 37th day of life). Follicle-stimulating (FSH), luteinizing (LH) and somatotropic (GH) cells were examined by the peroxidase-anti-peroxidase immunocytochemical method. Changes in cell volumes, volume densities and number per unit area (mm(2)) of FSH-, LH- and GH-immunoreactive cells were evaluated by stereology and morphometry. Serum FSH and LH levels were determined by RIA. Ovaries were analyzed by simple point counting of follicles. The volumes and volume densities of FSH-, LH- and GH-immunoreactive cells were significantly decreased while their numbers per mm(2) remained unchanged. SRIH-14 induced a significant decrease in serum FSH and LH levels. In the ovary, SRIH-14 induced an increase in the number of primordial follicles, followed by a reduction in the number of small healthy growing follicles and absence of preovulatory follicles. The number of atretic follicles was unchanged. We concluded that treatment with SRIH-14 during the peripubertal period markedly inhibited pituitary FSH, LH and GH cells. In the ovary, SRIH-14 acted by inhibiting folliculogenesis without affecting atretic processes.     

The Negative Effect of Soy Extract on Erythrocyte Membrane Fluidity: An Electron Paramagnetic Resonance Study

A decrease of erythrocyte membrane fluidity can contribute to the pathophysiology of hypertension. Soy products, which are used as alternative therapeutics in some cardiovascular conditions, contain various isoflavones (genistein, daidzein, and their glucosides, genistin and daidzin), which can incorporate cellular membrane and change its fluidity. The aim of this study was to examine the effects of soy extract (which generally corresponds to the soy products of isoflavone composition) on erythrocyte membrane fluidity at graded depths. We used electron paramagnetic resonance spectroscopy and fatty acid spin probes (5-DS and 12-DS), the spectra of which are dependent on membrane fluidity. After being treated with soy extract, erythrocytes showed a significant (P = 0.016) decrease of membrane fluidity near the hydrophilic surface, while there were no significant changes of fluidity in deeper hydrophobic membrane regions. These results suggest that soy products containing high levels of genistein and isoflavone glucosides may not be suitable for use in hypertension because they decrease erythrocyte membrane fluidity.