Sleep quality,chronotype, temperament and bipolar features as predictors of depressive symptoms among medical students

The assessment of risk factors is a crucial step in the prevention and treatment of affective disorders and should encompass personal dispositions. The aim of this study was to assess the value of chronotype and temperament as independent predictors of depressive symptoms among medical students. The study surveyed 140 students of the Faculty of Medicine with a battery of questionnaires: the Beck Depression Index (BDI), Hypomania Checklist 32 (HCL-32), Pittsburgh Sleep Quality Index (PSQI), Chronotype Questionnaire and Eysenck Personality Questionnaire Revised. The results were tested using Pearson’s correlation quotient and general linear model. Ten percent of the participants demonstrated a BDI score suggestive of clinically significant depressive symptoms. BDI score correlated positively with HCL-32 score. A rise in BDI was independently predicted by elevated Neuroticism and PSQI scores and morningness. Those effects were independent from each other and from other parameters of the model. The presence of depressive symptoms might be associated with bipolar features among medical students. Poor sleep quality predicted depressive symptoms, similarly to Neuroticism and independently of temperament and chronotype. Future studies on the associations between personal dispositions and mood disorders among medical students are required to help identify those at greater risk of developing affective illness. Effective prophylaxis and early intervention are warranted to ensure better treatment results.     

Influence of Ivabradine on the Anticonvulsant Action of Four Classical Antiepileptic Drugs Against Maximal Electroshock-Induced Seizures in Mice

Although the role of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in neuronal excitability and synaptic transmission is still unclear, it is postulated that the HCN channels may be involved in seizure activity. The aim of this study was to assess the effects of ivabradine (an HCN channel inhibitor) on the protective action of four classical antiepileptic drugs (carbamazepine, phenobarbital, phenytoin and valproate) against maximal electroshock-induced seizures in mice. Tonic seizures (maximal electroconvulsions) were evoked in adult male albino Swiss mice by an electric current (sine-wave, 25 mA, 0.2 s stimulus duration) delivered via auricular electrodes. Acute adverse-effect profiles of the combinations of ivabradine with classical antiepileptic drugs were measured in mice along with total brain antiepileptic drug concentrations. Results indicate that ivabradine (10 mg/kg, i.p.) significantly enhanced the anticonvulsant activity of valproate and considerably reduced that of phenytoin in the mouse maximal electroshock-induced seizure model. Ivabradine (10 mg/kg) had no impact on the anticonvulsant potency of carbamazepine and phenobarbital in the maximal electroshock-induced seizure test in mice. Ivabradine (10 mg/kg) significantly diminished total brain concentration of phenytoin and had no effect on total brain valproate concentration in mice. In conclusion, the enhanced anticonvulsant action of valproate by ivabradine in the mouse maximal electroshock-induced seizure model was pharmacodynamic in nature. A special attention is required when combining ivabradine with phenytoin due to a pharmacokinetic interaction and reduction of the anticonvulsant action of phenytoin in mice. The combinations of ivabradine with carbamazepine and phenobarbital were neutral from a preclinical viewpoint.     

The structured diversity of specialized gut symbionts of the New World army ants

Symbiotic bacteria play important roles in the biology of their arthropod hosts. Yet the microbiota of many diverse and influential groups remain understudied, resulting in a paucity of information on the fidelities and histories of these associations. Motivated by prior findings from a smaller scale, 16S rRNA‐based study, we conducted a broad phylogenetic and geographic survey of microbial communities in the ecologically dominant New World army ants (Formicidae: Dorylinae). Amplicon sequencing of the 16S rRNA gene across 28 species spanning the five New World genera showed that the microbial communities of army ants consist of very few common and abundant bacterial species. The two most abundant microbes, referred to as Unclassified Firmicutes and Unclassified Entomoplasmatales, appear to be specialized army ant associates that dominate microbial communities in the gut lumen of three host genera, Eciton, Labidus and Nomamyrmex. Both are present in other army ant genera, including those from the Old World, suggesting that army ant symbioses date back to the Cretaceous. Extensive sequencing of bacterial protein‐coding genes revealed multiple strains of these symbionts coexisting within colonies, but seldom within the same individual ant. Bacterial strains formed multiple host species‐specific lineages on phylogenies, which often grouped strains from distant geographic locations. These patterns deviate from those seen in other social insects and raise intriguing questions about the influence of army ant colony swarm‐founding and within‐colony genetic diversity on strain coexistence, and the effects of hosting a diverse suite of symbiont strains on colony ecology.     

Meiotic chromosome configurations in oocytes of <Emphasis Type="Italic">Cobitis taenia</Emphasis> and its polyploid hybrids

Diploid and triploid hybrid females of Cobitis as a rule produce unreduced eggs which mainly develop gynogenetically, but some of the eggs incorporate sperm genome and develop into triploids and tetraploids, respectively. Here, we observed for the first time the meiotic chromosomes in the germinal vesicles (GVs) of mature oocytes of three diploid C. taenia (2n = 48) and 20 allopolyploid females of Cobitis (18 triploid 3n = 74 and 2 tetraploid 4n = 99). The majority of GVs in diploid, triploid and tetraploid females contained 24, 74 and 96 or 99 bivalents, respectively. These results directly indicated premeiotic endomitosis as a mechanism underlying the formation of unreduced eggs in allopolyploid females of Cobitis.     

Reconstructed historical distribution and phylogeography unravels non-steppic origin of <Emphasis Type="Italic">Caucasotachea vindobonensis</Emphasis> (Gastropoda: Helicidae)

Existing data on the phylogeography of European taxa of steppic provenance suggests that species were widely distributed during glacial periods but underwent range contraction and fragmentation during interglacials into “warm-stage refugia.” Among the steppe-related invertebrates that have been examined, the majority has been insects, but data on the phylogeography of snails is wholly missing. To begin to fill this gap, phylogeographic and niche modeling studies on the presumed steppic snail Caucasotachea vindobonensis were conducted. Surprisingly, reconstruction of ancestral areas suggests that extant C. vindobonensis probably originated in the Balkans and survived there during the Late Pleistocene glaciations, with a more recent colonization of the Carpatho-Pannonian and the Ponto-Caspian regions. In the Holocene, C. vindobonensis colonized between the Sudetes and the Carpathians to the north, where its recent and current distribution may have been facilitated by anthropogenic translocations. Together, these data suggest a possible non-steppic origin of C. vindobonensis. Further investigation may reveal the extent to which the steppic snail assemblages consist partly of Holocene newcomers.     

Identification of mutations in theNF2 gene in Polish patients with neurofibromatosis type 2

Point mutation and loss of heterozygosity (LOH) analyses were performed in 12 Polish patients with a classic symptom of NF2 - bilateral vestibular schwannomas (BVS). In 5 patients (41.7%), germline mutations were found in the NF2 gene: 2 previously reported substitutions (c.592C>T and c.52C>T) and 3 novel mutations (c.1001_1002insG, c.1029_1030insCC, c.774_778dupGAATG). In addition, LOH analysis of 30 tumour samples from 10 patients revealed a molecular basis of NF2 in 3 patients (25%) that did not have any germline mutation. The molecular defects in sporadic cases of NF2 are still being discussed.     

A study of molecular interactions in light-harvesting complexes LHCIIb, CP29, CP26 and CP24 by Stark effect spectroscopy

Electric field-induced absorption changes (electrochromism or Stark effect) of the light-harvesting PSII pigment-protein complexes LHCIIb, CP29, CP26 and CP24 were investigated. The results indicate the lack of strong intermolecular interactions in the chlorophyll a (Chl a) pools of all complexes. Characteristic features occur in the electronic spectrum of Chl b, which reflect the increased values of dipole moment and polarizability differences between the ground and excited states of interacting pigment systems. The strong Stark signal recorded for LHCIIb at 650-655 nm is much weaker in CP29, where it is replaced by a unique Stark band at 639 nm. Electrochromism of Chl b in CP26 and CP24 is significantly weaker but increased electrochromic parameters were also noticed for the Chl b transition at 650 nm. The spectra in the blue region are dominated by xanthophylls. The differences in Stark spectra of Chl b are linked to differences in pigment content and organization in individual complexes and point to the possibility of electron exchange interactions between energetically similar and closely spaced Chl b molecules.