Quorum sensing activity of Citrobacter amalonaticus L8A, a bacterium isolated from dental plaque3/23/2016 Abstract:
Cell-cell communication is also known as quorum sensing (QS) that happens in the bacterial cells with the aim to regulate their genes expression in response to increased cell density. In this study, a bacterium (L8A) isolated from dental plaque biofilm was identified as Citrobacter amalonaticus by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). Its N-acylhomoserine-lactone (AHL) production was screened by using two types of AHL biosensors namely Chromobacterium violaceum CV026 and Escherichia coli [pSB401]. Citrobacter amalonaticus strain L8A was identified and confirmed producing numerous types of AHL namely N-butyryl-L-homoserine lactone (C4-HSL), N-hexanoyl-L-homoserine lactone (C6-HSL), N-octanoyl-L-homoserine lactone (C8-HSL) and N-hexadecanoyl-L-homoserine lactone (C16-HSL). We performed the whole genome sequence analysis of this oral isolate where its genome sequence reveals the presence of QS signal synthase gene and our work will pave the ways to study the function of the related QS genes in this bacterium. Source: SCIENTIFIC REPORTS Author: Goh SY, Khan SA, Tee KK, Abu Kasim NH, Yin WF, Chan KG Status: DOAJ as an open access journal at Nature
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A modified silk fibroin scaffold with mimic reconstructed extracellular matrix of decellularized pulp/collagen/fibronectin was proposed for bone tissueengineering in alveolar bone resorption. Silk fibroin scaffolds were fabricated by freeze-drying before modification by coating in a decellularizedpulp/collagen/fibronectin solution. The extracellular matrix reconstruction of the decellularized pulp/collagen/fibronectin and the morphology and biofunctionalities of the modified scaffolds were evaluated. The results showed that decellularized pulp/collagen/fibronectin organized into a dense dendrite structure and adhered in the scaffold in a fibrillar network. The modified scaffold showed predominant biofunctionalities and promise for bone tissueengineering in alveolar bone resorption. (C) 2015 Elsevier B.V. All rights reserved. Source: Materials Letters Author: Sangkert S, Kamonmattayakul S, Chai WL, Meesane J. Status: A paid open access available at ScienceDirect Abstract:
Men who have sex with men (MSM) living in countries with strong stigma toward MSM are vulnerable to HIV and experience significant barriers to HIV care. Research is needed to inform interventions to reduce stigma toward MSM in these countries, particularly among healthcare providers. A cross-sectional survey of 1158 medical and dental students was conducted at seven Malaysian universities in 2012. Multivariate analyses of variance suggest that studentswho had interpersonal contact with MSM were less prejudiced toward and had lower intentions to discriminate against MSM. Path analyses with bootstrapping suggest stereotypes and fear mediate associations between contact with prejudice and discrimination. Intervention strategies to reduce MSM stigma amonghealthcare providers in Malaysia and other countries with strong stigma toward MSM may include facilitating opportunities for direct, in-person or indirect, media-based prosocial contact between medical and dental students with MSM. Source: AIDS and Behavior Author: Earnshaw VA, Jin H, Wickersham JA, Kamarulzaman A, John J, Lim SH, Altice FL. Status: A paid open access available at Springer Abstract:
Background Nasopharyngeal carcinoma (NPC) is a neoplasm of the epithelial lining of the nasopharynx. Despite various reports linking genomic variants to NPC predisposition, very few reports were done on copy number variations (CNV). CNV is an inherent structural variation that has been found to be involved in cancer predisposition. Methods A discovery cohort of Malaysian Chinese descent (NPC patients, n = 140; Healthy controls, n = 256) were genotyped using Illumina (R) HumanOmniExpress BeadChip. PennCNV and cnvPartition calling algorithms were applied for CNV calling. Taqman CNV assays and digital PCR were used to validate CNV calls and replicate candidate copy number variant region (CNVR) associations in a follow-up Malaysian Chinese (NPC cases, n = 465; and Healthy controls, n = 677) and Malay cohort (NPC cases, n = 114; Healthy controls, n = 124). Results Six putative CNVRs overlapping GRM5, MICA/HCP5/HCG26, LILRB3/LILRA6, DPY19L2, RNase3/RNase2 and GOLPH3 genes were jointly identified by PennCNV and cnvPartition. CNVs overlapping GRM5 and MICA/HCP5/HCG26 were subjected to further validation by Taqman CNV assays and digital PCR. Combined analysis in Malaysian Chinese cohort revealed a strong association at CNVR on chromosome 11q14.3 (P-combined = 1.54x10(-5); odds ratio (OR) = 7.27; 95% CI = 2.96-17.88) overlapping GRM5 and a suggestive association at CNVR on chromosome 6p21.3 (P-combined = 1.29x10(-3); OR = 4.21; 95% CI = 1.75-10.11) overlapping MICA/HCP5/HCG26 genes. Conclusion Our results demonstrated the association of CNVs towards NPC susceptibility, implicating a possible role of CNVs in NPC development. Author: Low JSY, Chin YM, Mushiroda T, Kubo M, Govindasamy GK, Pua KC, Yap YY, Yap LF, Subramaniam SK, Ong CA, et al. Source: PLoS One Status: Open Access available at PLoS One Abstract:
Approximately 20% of global cancer incidence is causally linked to an infectious agent. Epstein-Barr virus (EBV) accounts for around 1% of all virus-associated cancers and is associated with nasopharyngeal carcinoma (NPC). Latent membrane protein 1 (LMP1), the major oncoprotein encoded by EBV, behaves as a constitutively active tumour necrosis factor (TNF) receptor activating a variety of signalling pathways, including the three classic MAPKs (ERK-MAPK, p38 MAPK and JNK/SAPK). The present study identifies novel signalling properties for this integral membrane protein via the induction and secretionof activin A and TGF beta 1, which are both required for LMP1's ability to induce the expression of the extracellular matrix protein, fibronectin. However, it is evident that LMP1 is unable to activate the classic Smad-dependent TGF beta signalling pathway, but rather elicits its effects through the non-Smad arm ofTGF beta signalling. In addition, there is a requirement for JNK/SAPK signalling in LMP1-mediated fibronectin induction. LMP1 also induces the expression and activation of the major fibronectin receptor, alpha 5 beta 1 integrin, an effect that is accompanied by increased focal adhesion formation and turnover. Taken together, these findings support the putative role for LMP1 in the pathogenesis of NPC by contributing to the metastatic potential of epithelial cells. Author: Morris MA, Dawson CW, Laverick L, Davis AM, Dudman JPR, Ravennthiraraj S, Ahmad Z, Yap LF, Young LS. Source: Scientific Reports Status: Open Access available at Nature Abstract:
In severe syndromic craniosynostosis, distraction osteogenesis (DO) provides superior segmental advancement and allows progressive clinical monitoring to ensure that adequate skeletal expansion is achieved. We report two cases of Crouzon syndrome involving a 3-year-old boy and a 4-year-old girl, who were both treated with monobloc Le Fort III DO using a combination of external and internal distraction devices (Synthes, Oberdorf, Switzerland) to treat severe orbital proptosis and obstructed nasopharyngeal airway secondary to severe hypoplastic craniofacial skeletal components. Their skeletal segments were advanced in daily increments by 27 mm and 23 mm, respectively. Results at 18 months postoperatively showed successful outcomes, as evidenced by adequate eye protection, tracheostomy tube decannulation following objective evidence of patent nasopharyngeal airway, and acceptable facial appearance. Monobloc Le Fort III DO using a combination of external and internal devices produces favorable functional and clinical outcomes for the treatment of severe orbital and airway discrepancy in Crouzon syndrome. Author: Hariri F, Cheung LK, Rahman ZAA, Mathaneswaran V, Ganesan D. Status: Full text available at CPC Journal Abstract:
Background: The regulation of specific target genes by transcription factors is central to our understanding of gene network control in developmental and physiological processes yet how target specificity is achieved is still poorly understood. This is well illustrated by the Hox family of transcription factors as their limited in vitro DNA-binding specificity contrasts with their clear in vivo functional specificity. Results: We generated genome-wide binding profiles for three Hox proteins, Ubx, Abd-A and Abd-B, following transient expression in Drosophila Kc167 cells, revealing clear target specificity and a striking influence of chromatin accessibility. In the absence of the TALE class homeodomain cofactors Exd and Hth, Ubx and Abd-A bind at a very similar set of target sites in accessible chromatin, whereas Abd-B binds at an additional specific set of targets. Provision of Hox cofactors Exd and Hth considerably modifies the Ubx genome-wide binding profile enabling Ubx to bind at an additional novel set of targets. Both the Abd-B specific targets and the cofactor-dependent Ubx targets are in chromatin that is relatively DNase1 inaccessible prior to the expression of Hox proteins/Hox cofactors. Conclusions: Our experiments demonstrate a strong role for chromatin accessibility in Hox protein binding and suggest that Hox protein competition with nucleosomes has a major role in Hox protein target specificity in vivo. Author: Beh CY, El-Sharnouby S, Chatzipli A, Russell S, Choo SW, White R. Source: DOAJ as an open access journal at Biomed Central Abstract:
Long-term culture system is used to prevent the impediment of insufficient cells and is good for low starting materials such as dental pulp or periodontal ligament. In general, although cell viability and functionality are the most common aspects taken into consideration in culturing cells for a long term, they may not truly represent the biological state of the cells. Hence, we explored the behaviour of another important aspect which is the immune properties in long-term cultured cells. Dental pulp stem cells from deciduous (SHED; n = 3) and permanent (DPSCs; n = 3) teeth as well as periodontal ligament stem cells (PDLSCs; n = 3) were cultured under identical culture condition. The immune properties of each cell lines were profiled at passage 2 [P2] and passage 9 [P9] as early and late passages, respectively. This was further validated at the protein level using the Luminex platform. A major shift of genes was noticed at P9 with SHED being the highest. SHED cultured at P9 displayed many genes representing pathogen recognition (P < 0.001), immune signalling (P < 0.001, pro-inflammatory (P < 0.001), anti-inflammatory (P < 0.001) and immune-related growth and stimulation factor (P < 0.001) as compared to DPSCs and PDLSCs. Surprisingly, SHED also expressed many cytotoxicity genes (P < 0.001). Communally, instabilities of immune genes from our findings suggest that long-term cultured cells may not be feasible for transplantation purposes. A complete biological characterization covering all major aspects including immune properties should be made as prerequisite criteria prior to the use of long-term cultured stem cells in clinical settings. Author: Jayaraman P, Govindasamy V, Gnanasegaran N, Kunasekaran W, Vasanthan P, Musa S, Abu Kasim NH. Status: A paid open access option is available for this journal. at Springer |