Functional symmetries in the schmelzmuster and morphology of rootless rodent molars

Morphology and schmelzmuster of rootless cheek teeth of 25 extant rodent genera were studied in relation to jaw movement. A differentiation between leading and trailing edges is observed regularly in enamel thickness and schmelzmuster. Similarities between antagonists are interpreted as 'functional symmetries'. Differences in the enamel thickness, the schmelzmuster and orientation of cutting edges are controlled by functional and phylogenetic constraints. The heterogenous sample allows discrimination between these two constraints. The most obvious functional constraint leads to the almost regular occurrence of radial enamel on the push sides of cutting edges. The degree of functional symmetry seems to be determined by phylogenetic limitations.     

The effect of mesenchymal stem cells and imatinib on macrophage polarization in rat model of liver fibrosis

Liver fibrosis is a disorder in which inflammatory reactions play an important role, and central to the progression and pathogenesis of this disease are the immune-specific cells known as macrophages. Macrophage types are distinguished from each other by the expression of a series of surface markers. STAT6 and Arg1 play an important role in the polarization of macrophages, so these two factors are downstream of interleukin 4 (IL-4) and IL-13 cytokines and cause to differentiate M2. Therefore, this study aimed to compare the independent effects of imatinib and mesenchymal cell treatment on the polarization of macrophages in rat models of liver fibrosis. The liver fibrosis was induced by the injection of CCL4 for 6 weeks in Sprague–Dawley rats. Then, rats were divided into four different groups, and the effects of imatinib and mesenchymal cells on the expression of Arg1, Ly6c, and STAT6 were evaluated. Histopathology experiments considered the amelioration effect of treatments. Our results showed that Arg1 expression was significantly increased in the groups treated with mesenchymal cells and imatinib compared to the control group. On the other hand, expression of STAT6 was significantly increased in the imatinib-treated mice compared to mesenchymal and control groups. Moreover, the expression of LY6C significantly decreased in imatinib and mesenchymal treated groups compared to the control group. Therefore, our data showed that mesenchymal stem cells and imatinib significantly modulate the fibrotic process in rat models of fibrosis, probably by polarizing macrophages towards an anti-inflammatory profile and increasing the frequency of these cells in liver tissue.     

Block of outward current in cardiac purkinje fibers by injection of quaternary ammonium ions

We have studied the effects of iontophoretic injection of the quaternary ammonium compounds tetraethylammonium (TEA) and tetrabutylammonium (TBA) in cardiac purkinje fibers. We find that TBA(+) is a more effective blocker than TEA(+), but injection of either compound reduces the time-dependent outward plateau currents, transient outward current (I(to)), and the delayed rectifier (I(x)). Our findings provide evidence that these outward cardiac currents are carried by channels that in some respects are pharmacologically similar to squid axon potassium channels. We demonstrate that this procedure is a new tool that can be useful in the analysis of membrane currents in the heart.     

Quantification of the magnification and distortion effects of a pediatric flexible video-bronchoscope

Background

Flexible video bronchoscopes, in particular the Olympus BF Type 3C160, are commonly used in pediatric respiratory medicine. There is no data on the magnification and distortion effects of these bronchoscopes yet important clinical decisions are made from the images. The aim of this study was to systematically describe the magnification and distortion of flexible bronchoscope images taken at various distances from the object.

Methods

Using images of known objects and processing these by digital video and computer programs both magnification and distortion scales were derived.

Results

Magnification changes as a linear function between 100 mm (×1) and 10 mm (×9.55) and then as an exponential function between 10 mm and 3 mm (×40) from the object. Magnification depends on the axis of orientation of the object to the optic axis or geometrical axis of the bronchoscope. Magnification also varies across the field of view with the central magnification being 39% greater than at the periphery of the field of view at 15 mm from the object. However, in the paediatric situation the diameter of the orifices is usually less than 10 mm and thus this limits the exposure to these peripheral limits of magnification reduction. Intraclass correlations for measurements and repeatability studies between instruments are very high, r = 0.96. Distortion occurs as both barrel and geometric types but both types are heterogeneous across the field of view. Distortion of geometric type ranges up to 30% at 3 mm from the object but may be as low as 5% depending on the position of the object in relation to the optic axis.

Conclusion

We conclude that the optimal working distance range is between 40 and 10 mm from the object. However the clinician should be cognisant of both variations in magnification and distortion in clinical judgements.     

Sperm competition and the evolution of sperm design in mammals

Background  

The influence of sperm competition upon sperm size has been a controversial issue during the last 20 years which remains unresolved for mammals. The hypothesis that, when ejaculates compete with rival males, an increase in sperm size would make sperm more competitive because it would increase sperm swimming speed, has generated contradictory results from both theoretical and empirical studies. In addition, the debate has extended to which sperm components should increase in size: the midpiece to accommodate more mitochondria and produce more energy to fuel motility, or the principal piece to generate greater propulsion forces.     

The translation initiation complex eIF3 in trypanosomatids and other pathogenic excavates – identification of conserved and divergent features based on orthologue analysis

Background

The initiation of translation in eukaryotes is supported by the action of several eukaryotic Initiation Factors (eIFs). The largest of these is eIF3, comprising of up to thirteen polypeptides (eIF3a through eIF3m), involved in multiple stages of the initiation process. eIF3 has been better characterized from model organisms, but is poorly known from more diverged groups, including unicellular lineages represented by known human pathogens. These include the trypanosomatids (Trypanosoma and Leishmania) and other protists belonging to the taxonomic supergroup Excavata (Trichomonas and Giardia sp.).

Results

An in depth bioinformatic search was carried out to recover the full content of eIF3 subunits from the available genomes of L. major, T. brucei, T. vaginalis and G. duodenalis. The protein sequences recovered were then submitted to homology analysis and alignments comparing them with orthologues from representative eukaryotes. Eleven putative eIF3 subunits were found from both trypanosomatids whilst only five and four subunits were identified from T. vaginalis and G. duodenalis, respectively. Only three subunits were found in all eukaryotes investigated, eIF3b, eIF3c and eIF3i. The single subunit found to have a related Archaean homologue was eIF3i, the most conserved of the eIF3 subunits. The sequence alignments revealed several strongly conserved residues/region within various eIF3 subunits of possible functional relevance. Subsequent biochemical characterization of the Leishmania eIF3 complex validated the bioinformatic search and yielded a twelfth eIF3 subunit in trypanosomatids, eIF3f (the single unidentified subunit in trypanosomatids was then eIF3m). The biochemical data indicates a lack of association of the eIF3j subunit to the complex whilst highlighting the strong interaction between eIF3 and eIF1.

Conclusions

The presence of most eIF3 subunits in trypanosomatids is consistent with an early evolution of a fully functional complex. Simplified versions in other excavates might indicate a primordial complex or secondary loss of selected subunits, as seen for some fungal lineages. The conservation in eIF3i sequence might indicate critical functions within eIF3 which have been overlooked. The identification of eIF3 subunits from distantly related eukaryotes provides then a basis for the study of conserved/divergent aspects of eIF3 function, leading to a better understanding of eukaryotic translation initiation.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-1175) contains supplementary material, which is available to authorized users.