Eastern Beringian biogeography: historical and spatial genetic structure of singing voles in Alaska

Aim  Pleistocene climatic cycles have left marked signatures in the spatial and historical genetic structure of high‐latitude organisms. We examine the mitochondrial (cytochrome b) genetic structure of the singing vole, Microtus miurus (Rodentia: Cricetidae: Arvicolinae), a member of the Pleistocene Beringian fauna, and of the insular vole, Microtus abbreviatus, its putative sister species found only on the St Matthew Archipelago. We reconstruct the phylogenetic and phylogeographical structure of these taxa, characterize their geographical partitioning and date coalescent and cladogenetic events in these species. Finally, we compare the recovered results with the phylogenetic, coalescent and spatial genetic patterns of other eastern Beringian mammals and high‐latitude arvicoline rodents. Location  Continental Alaska (alpine and arctic tundra) and the St Matthew Archipelago (Bering Sea). Methods  We generated and analysed cytochrome b sequences of 97 singing and insular voles (M. miurus and M. abbreviatus) from Alaska. Deep evolutionary structure was inferred by phylogenetic analysis using parsimony, maximum likelihood and Bayesian approaches; the geographical structure of genetic diversity was assessed using analysis of molecular variance and network analysis; ages of cladogenetic and coalescent events were estimated using a relaxed molecular clock model with Bayesian approximation. Results  Regional nucleotide diversity in singing voles is higher than in other high‐latitude arvicoline species, but intra‐population diversity is within the observed range of values for arvicolines. Microtus abbreviatus specimens are phylogenetically nested within M. miurus. Molecular divergence date estimates indicate that current genetic diversity was formed in the last glacial (Wisconsinan) and previous interglacial (Sangamonian) periods, with the exception of a Middle Pleistocene split found between samples collected in the Wrangell Mountains region and all other singing vole samples. Main conclusions  High levels of phylogenetic and spatial structure are observed among analysed populations. This pattern is consistent with that expected for a taxon with a long history in Beringia. The spatial genetic structure of continental singing voles differs in its northern and southern ranges, possibly reflecting differences in habitat distribution between arctic and alpine tundra. Our phylogenetic results support the taxonomic inclusion of M. miurus in its senior synonym, M. abbreviatus.     

Autologous and allogeneic stimulation of peripheral human leukocytes

Lymphoid cell lines have been established from four normal donors. When irradiated cells from these lines were mixed with either allogeneic or autologous peripheral leukocytes, marked increases in thymidine incorporation by the peripheral leukocytes were noted.     

Antigen-induced in vitro inhibition of immune responsiveness

Addition of the dinitrophenyl derivative of the copolymer of d-glutamic acid and d-lysine (DNP-d-GL) or dinitrophenyl bovine γ-globulin (DNP-BGG) to spleen cell cultures specifically inhibited their capacity to produce an anti-DNP plaque-forming cell (PFC) response to the T-independent antigen dinitrophenylated polyacrylamide beads (DNP-PAA) or to the T-dependent antigen TNP-burro erythrocytes. The degree of unresponsiveness was dependent upon the tolerogen concentration and the duration over which the tolerogen was present in the culture. Treatment with rabbit anti-mouse brain antiserum and complement did not alter the induction of unresponsiveness suggesting a state of B-cell tolerance. Culture of spleen cells for 4 days in the absence of antigen led to the appearance of nonspecific suppressor activity which was demonstrable by its effect on the response of fresh spleen cells to antigen. Preculture in the presence of the immunogen DNP-PAA induced both nonspecific and specific suppressor activities. Induction of specific suppressor activity was not prevented by the presence of the tolerogen DNP-D-GL in the culture. The suppressor activity resided in an adherent T-cell population and did not appear to require macrophages for its induction.     

Antimicrobial susceptibility patterns,emm type distribution and genetic diversity of Streptococcus pyogenes recovered in Brazil

Streptococcus pyogenes is responsible for a variety of infectious diseases and immunological complications. In this study, 91 isolates of S. pyogenes recovered from oropharynx secretions were submitted to antimicrobial susceptibility testing, emm typing and pulsed-field gel electrophoresis (PFGE) analysis. All isolates were susceptible to ceftriaxone, levofloxacin, penicillin G and vancomycin. Resistance to erythromycin and clindamycin was 15.4%, which is higher than previous reports from this area, while 20.9% of the isolates were not susceptible to tetracycline. The macrolide resistance phenotypes were cMLSB (10) and iMLSB (4). The ermB gene was predominant, followed by the ermA gene. Thirty-two emm types and subtypes were found, but five (emm1, emm4, emm12, emm22, emm81) were detected in 48% of the isolates. Three new emm subtypes were identified (emm1.74, emm58.14, emm76.7). There was a strong association between emm type and PFGE clustering. A variety of PFGE profiles as well as emm types were found among tetracycline and erythromycin-resistant isolates, demonstrating that antimicrobial resistant strains do not result from the expansion of one or a few clones. This study provides epidemiological data that contribute to the development of suitable strategies for the prevention and treatment of such infections in a poorly studied area.     

Only one independent genetic association with rheumatoid arthritis within the KIAA1109-TENR-IL2-IL21 locus in Caucasian sample sets: confirmation of association of rs6822844 with rheumatoid arthritis at a genome-wide level of significance

Introduction

To investigate whether accelerated hand bone mineral density (BMD) loss is associated with progressive joint damage in hands and feet in the first year of rheumatoid arthritis (RA) and whether it is an independent predictor of subsequent progressive total joint damage after 4 years.

Methods

In 256 recent-onset RA patients, baseline and 1-year hand BMD was measured in metacarpals 2-4 by digital X-ray radiogrammetry. Joint damage in hands and feet were scored in random order according to the Sharp-van der Heijde method at baseline and yearly up to 4 years.

Results

68% of the patients had accelerated hand BMD loss (>-0.003 g/cm²) in the first year of RA. Hand BMD loss was associated with progressive joint damage after 1 year both in hands and feet with odds ratios (OR) (95% confidence intervals [CI]) of 5.3 (1.3-20.9) and 3.1 (1.0-9.7). In univariate analysis, hand BMD loss in the first year was a predictor of subsequent progressive total joint damage after 4 years with an OR (95% CI) of 3.1 (1.3-7.6). Multivariate analysis showed that only progressive joint damage in the first year and anti-citrullinated protein antibody positivity were independent predictors of long-term progressive joint damage.

Conclusions

In the first year of RA, accelerated hand BMD loss is associated with progressive joint damage in both hands and feet. Hand BMD loss in the first year of recent-onset RA predicts subsequent progressive total joint damage, however not independent of progressive joint damage in the first year.     

Plasmodium falciparum Adhesion on Human Brain Microvascular Endothelial Cells Involves Transmigration-Like Cup Formation and Induces Opening of Intercellular Junctions

Cerebral malaria, a major cause of death during malaria infection, is characterised by the sequestration of infected red blood cells (IRBC) in brain microvessels. Most of the molecules implicated in the adhesion of IRBC on endothelial cells (EC) are already described; however, the structure of the IRBC/EC junction and the impact of this adhesion on the EC are poorly understood. We analysed this interaction using human brain microvascular EC monolayers co-cultured with IRBC. Our study demonstrates the transfer of material from the IRBC to the brain EC plasma membrane in a trogocytosis-like process, followed by a TNF-enhanced IRBC engulfing process. Upon IRBC/EC binding, parasite antigens are transferred to early endosomes in the EC, in a cytoskeleton-dependent process. This is associated with the opening of the intercellular junctions. The transfer of IRBC antigens can thus transform EC into a target for the immune response and contribute to the profound EC alterations, including peri-vascular oedema, associated with cerebral malaria.     

Lung hernia after video-assisted thoracoscopic lobectomy

Lung hernias are rare and are most commonly secondary to blunt or penetrating trauma. Few cases have been reported after video-assisted thoracoscopic surgery and only one case after video-assisted thoracoscopic surgery lobectomy. We report a case of lung hernia after video-assisted, thoracoscopic, right upper lobectomy. The hernia was demonstrated by computerized tomography and repaired by minimally invasive techniques. We believe that the combination of removal of a large lung specimen and the presence of emphysema may predispose to lung herniation after thoracoscopic lobectomy. Thoracic surgeons should be aware of this possible complication.     

New fossil records of Tapirus (Mammalia, Perissodactyla) from Brazil, with a critical analysis of intra-generic diversity assessments based on lower molar size variability

A large set of South American fossils belonging to the genus Tapirus has been described on the basis of differences in size and proportions of lower molariform teeth. Nevertheless, the reliability of dental proportions for the diagnosis of fossil tapir species is controversial. In this paper, we describe new fossil material of Tapirus from the Quaternary of Serra da Bodoquena, Southwestern Brazil, comparing it to other fossil and extant specimens of the genus by means of multivariate morphometric analyses of lower molariform teeth linear dimensions. The results of Principal Component Analyses indicate that some of the extant and extinct material attributed to Tapirus fall within the range of variation in size and proportions of lower molariform teeth exhibited by recent species of the genus. Therefore, part of the fossil material attributed to new species or to Tapirus sp. may be referable to the extant species Tapirus terrestris. We conclude that the sole use of lower molariform teeth size and proportions to erect new species of Tapirus may not be reliable, and therefore we advocate caution when describing fossil tapirs exclusively based on these criteria.     

Tyrosine phosphorylation of VE-cadherin and claudin-5 is associated with TGF-β1-induced permeability of centrally derived vascular endothelium

Breakdown of the inner blood-retinal barrier and the blood-brain barrier is associated with changes in tight and adherens junction-associated proteins that link vascular endothelial cells. This study aimed to test the hypothesis that transforming growth factor (TGF)-β1 increases the paracellular permeability of vascular endothelial monolayers through tyrosine phosphorylation of VE-cadherin and claudin-5. Bovine retinal and human brain capillary endothelial cells were grown as monolayers on coated polycarbonate membranes. Paracellular permeability was studied by measuring the equilibration of (14)C-inulin or fluorescence-labelled dextran. Changes in VE-cadherin and claudin-5 expression were studied by immunocytochemistry (ICC) and quantified by cell-based enzyme linked immunosorbent assays (ELISA). Tyrosine phosphorylation of VE-cadherin and claudin-5 was studied by ICC, immunoprecipitation and Western blotting. We found that exposure of endothelial cells to TGF-β1 caused a dose-dependent increase in paracellular permeability as reflected by increases in the equilibration of (14)C-inulin. This effect was enhanced by the tyrosine phosphatase inhibitor orthovanadate and attenuated by the tyrosine kinase inhibitor lavendustin A. ICC and cell-based ELISA revealed that TGF-β1 induced both dose- and time-dependent decreases in VE-cadherin and claudin-5 expression. Assessment of cell viability indicated that changes in these junction-associated proteins were not due to endothelial death or injury. ICC revealed that tyrosine phosphorylation of endothelial monolayers was greatly enhanced by TGF-β1 treatment, and immunoprecipitation of cell lysates showed increased tyrosine phosphorylation of VE-cadherin and claudin-5. Our results suggest that tyrosine phosphorylation of VE-cadherin and claudin-5 is involved in the increased paracellular permeability of central nervous system-derived vascular endothelium induced by TGF-β1.