Ab initio study of the giant ferroelectric distortion and pressure induced spin-state transition in BiCoO3

Using configuration-state-constrained electronic structure calculations based on the generalized gradient approximation plus Hubbard U method, we sought the origin of the giant tetragonal ferroelectric distortion in the ambient phase of the potentially multiferroic material BiCoO3 and identified the nature of the pressure induced spin-state transition. Our results show that a strong Bi-O covalency drives the giant ferroelectric distortion, which is further stabilized by an xy-type orbital ordering of the high-spin (HS) Co3+ ions. For the orthorhombic phase under 5.8 GPa, we find that a mixed HS and low-spin (LS) state is more stable than both LS and intermediate-spin (IS) states, and that the former well accounts for the available experimental results. Thus, we identify that the pressure induced spin-state transition is via a mixed HS+LS state, and we predict that the HS-to-LS transition would be complete upon a large volume decrease of about 20%.Comment: 6 pages, 6 figures, 2 table

The characterization of conserved binding motifs and potential target genes for M. tuberculosis MtrAB reveals a link between the two-component system and the drug resistance of M. smegmatis

<p>Abstract</p> <p>Background</p> <p>The two-component systems of <it>Mycobacterium tuberculosis </it>are apparently required for its growth and resistance in hostile host environments. In such environments, MtrAB has been reported to regulate the expression of the <it>M. tuberculosis </it>replication initiator gene, <it>dnaA</it>. However, the <it>dnaA </it>promoter binding sites and many potential target genes for MtrA have yet to be precisely characterized.</p> <p>Results</p> <p>In this study, a 7 bp sequence motif in the <it>dnaA </it>promoter region was identified for MtrA binding using DNaseI footprinting assays and surface plasmon resonance (SPR) analysis. Approximately 420 target genes potentially regulated by MtrA, including the isoniazid inducible gene <it>iniB</it>, were further characterized from <it>M. tuberculosis </it>and <it>M. smegmatis </it>genomes. When assayed using quantitative real-time PCR (qRT-PCR), many of the target genes demonstrated significant expression changes when the antisense mRNA of the <it>mtrA </it>gene was expressed in <it>M. smegmatis</it>. The recombinant mycobacteria grew in length and were more sensitive to two anti-tuberculosis drugs, isoniazid and streptomycin.</p> <p>Conclusions</p> <p>These findings yield critical information about the regulatory mechanisms of the MtrAB two-component system and its role in the drug resistance of <it>M. smegmatis</it>.</p

Expression of hypoxia inducible factor-1α and vascular endothelial growth factor-C in human chronic periodontitis

AbstractBackground/purposeEvidence shows that there is a relationship between hypoxia and inflammatory response in periodontitis. Hypoxia-inducible factor (HIF)-1α is a major regulator of energy homeostasis and cellular adaptation to low oxygen stress. Although experimental results demonstrate an association between HIF-1α and vascular endothelial growth factor (VEGF)-C in tumor angiogenesis, the role of HIF-1α and VEGF-C in the pathogenesis of periodontitis is still ambiguous. So far, limited attention has been given to the role of hypoxia and VEGF-C in periodontitis. The present study aimed to investigate the expression and distribution of HIF-1α and VEGF-C in gingival tissue samples from patients with different stages of chronic periodontitis and healthy individuals.Materials and methodsA total of 56 samples were involved in this study, including moderate chronic periodontitis (n = 20), advanced chronic periodontitis (n = 20), and healthy control tissues (n = 16). The gingival specimens were stained with hematoxylin and eosin for histopathology. The expression of HIF-1α and VEGF-C in gingival tissues was detected by immunohistochemical staining.ResultsHIF-1α and VEGF-C were found in gingival tissues from patients with different stages of chronic periodontitis as well as healthy control tissues. HIF-1α protein was expressed mainly in the epithelial layer of gingival tissues, and VEGF-C protein was mostly located in the connective tissue papilla of gingival tissues. Compared with healthy controls, the expression of HIF-1α and VEGF-C in chronic periodontitis groups was significantly higher (P < 0.01), and the density of HIF-1α and VEGF-C in advanced chronic periodontitis group was even significantly higher than that in the moderate chronic periodontitis group (P < 0.01).ConclusionOur results suggest that the expression of HIF-1α and VEGF-C increased with severity of periodontitis. So, we conclude that HIF-1α may play an important role in the pathophysiology of human periodontitis and may be related to the function of VEGF-C during periodontitis

Genetic diversity analysis of cocksfoot (Dactylis glomerata L.) accessions with sequence-related amplified polymorphism (SRAP) and inter-simple sequence repeat (ISSR) markers

Sequence-related amplified polymorphism (SRAP) and inter-simple sequence repeat (ISSR), two advanced molecular markers for genetic research in grass and forage, were used to analyze the genetic diversity among 44 accessions of cocksfoot collected from seven countries and regions. 21 SRAP primer combinations generated 476 bands, of which 401 were polymorphic (84.24%). Using 12 ISSR primers, 100 polymorphic bands out of 115 bands in total were generated (86.96%). The coefficient of genetic similarity from SRAP and ISSR data ranged from 0.6838 to 0.9686 and from 0.6935 to 0.9231, respectively. Based on unweighted pair group method with arithmetic mean (UPGMA) cluster and principal component analysis (PCA) on a series of genetic characteristics, all accessions were divided into three clusters and four clusters using two markers, respectively. Those, accessions collected from the identical continent were classified into the same cluster, suggesting the geographical distribution of genetic diversity of cocksfoot. The genetic diversity of Chinese cocksfoot except for three Chinese cultivars was rather rich and greater than that of other regions. We proposed that both SRAP and ISSR markers were considered as useful tools for evaluating the genetic diversity of cocksfoot. Especially, SRAP detected more variance and gave clearer cluster groups.Keywords: Cocksfoot, genetic diversity, sequence-related amplified polymorphism (SRAP), inter-simple sequence repeat (ISSR), germplas

Treatment of osteonecrosis of femoral head with BMSCs-seeded bio-derived bone materials combined with rhBMP-2 in rabbits

ObjectiveTo evaluate the effect of autologous bone marrow mesenchymal stem cells (BMSCs) seeded bio-derived bone materials (BBM) combined with recombinant human bone morphogenetic protein-2 (rhBMP-2) in repairing defect of osteonecrosis of femoral head (ONFH).MethodsEarly-stage osteonecrosis in the left hip was induced in 36 adult New Zealand white rabbits (provided by the Animal Center of Guangxi Medical University, Nanning, China) after core decompression and delivery of liquid nitrogen into the femoral head. Then the animals were divided into three groups according to the type of implants for bone repair: 12 rabbits with nothing (Group I, the blank control group), 12 with BBM combined with rhBMP-2 (Group II), and 12 with BMSCs-seeded BBM combined with rhBMP-2 (Group III). At 4, 8, and 12 weeks after surgery, X-ray of the femoral head of every 4 rabbits in each group was taken, and then they were killed and the femoral heads were collected at each time point, respectively. Gross observation was made on the femoral heads. After hematoxylin and eosin staining, Lane-sandhu scores of X-ray and bone densitometry were calculated and the histomorphometric measurements were made for the new bone trabeculae.ResultsAt 12 weeks after surgery, two femoral heads collapsed in Group I, but none in Group II or Group III. X-ray examination showed that the femoral heads in Group I had defect shadow or collapsed while those in Group II had a low density and those in Group III presented with a normal density. Histologically, the defects of femoral heads were primarily filled with no new bone but fibrous tissues in Group I. In contrast, new bone regeneration and fibrous tissues occurred in Group II and only new bone regeneration occurrd in Group III. Lane-sandhu scores of X-ray, bone mineral density and rate of new bone in trabecular area in Group III were higher significantly than those of the other two groups.ConclusionsOur findings indicate a superior choice of repairing the experimental defect of ONFH with BMSCs-seeded BBM combined with rhBMP-2

Genetic Analysis of Seven Patients with Inherited Ichthyosis and Nagashima-Type Palmoplantar Keratoderma

Inherited ichthyosis comprises a series of heterogeneous dermal conditions; it mainly manifests as widespread hyperkeratosis, xerosis and scaling of the skin. At times, overlapping symptoms require differential diagnosis between ichthyosis and several other similar disorders. The present study reports seven patients with confirmed or suspected to be associated with ichthyosis by conducting a thorough clinical and genetic investigation. Genetic testing was conducted using whole-exome sequencing, with Sanger sequencing as the validation method. The MEGA7 program was used to analyze the conservation of amino acid residues affected by the detected missense variants. The enrolled patients exhibited ichthyosis-like but distinct clinical manifestations. Genetic analysis identified diagnostic variations in the FLG, STS, KRT10 and SERPINB7 genes and clarified the carrying status of each variant in the respective family members. The two residues affected by the detected missense variants remained conserved across multiple species. Of note, the two variants, namely STS: c.452C\u3eT(p.P151L) and c.647_650del(p.L216fs) are novel. In conclusion, a clear genetic differential diagnosis was made for the enrolled ichthyosis-associated patients; the study findings also extended the mutation spectrum of ichthyosis and provided solid evidence for the counseling of the affected families