777 research outputs found
Endemic, endangered and evolutionarily significant: cryptic lineages in Seychelles' frogs (Anura: Sooglossidae)
Cryptic diversity corresponding with island of origin has been previously reported in the endemic, geographically restricted sooglossid frogs of the Seychelles archipelago. The evolutionary pattern behind this has not been fully explored, and given current amphibian declines and the increased extinction risk faced by island species, we sought to identify evolutionarily significant units (ESUs) to address conservation concerns for these highly threatened anurans. We obtained genetic data for two mitochondrial (mtDNA) and four nuclear (nuDNA) genes from all known populations of sooglossid frog (on the islands of Mahé, Praslin and Silhouette) for phylogenetic analyses and to construct nuDNA haplotype networks. Bayesian and maximum likelihood analyses of mtDNA support the monophyly and molecular differentiation of populations in all species that occur on multiple islands. Haplotype networks using statistical parsimony revealed multiple high-frequency haplotypes shared between islands and taxa, in addition to numerous geographically distinct (island-specific) haplotypes for each species. We consider each island-specific population of sooglossid frog as an ESU and advise conservation managers to do likewise. Furthermore, our results identify each island lineage as a candidate species, evidence for which is supported by analyses of mtDNA based on Bayesian Poisson tree processes, and independent analyses of mtDNA and nuDNA using the multispecies coalescent. Our findings add to the growing understanding of the biogeography and hidden diversity within this globally important region
Conservation genomics reveals possible illegal trade routes and admixture across pangolin lineages in Southeast Asia
The use of genome-wide genetic markers is an emerging approach for informing evidence-based management decisions for highly threatened species. Pangolins are the most heavily trafficked mammals across illegal wildlife trade globally, but critically endangered Sunda pangolins (Manis javanica) have not been widely studied in insular Southeast Asia. We used > 12,000 single nucleotide polymorphic markers (SNPs) to assign pangolin seizures from illegal trade of unknown origin to possible geographic sources via genetic clustering with pangolins of known origin. Our SNPs reveal three previously unrecognized genetic lineages of Sunda pangolins, possibly from Borneo, Java and Singapore/Sumatra. The seizure assignments suggest the majority of pangolins were traded from Borneo to Java. Using mitochondrial markers did not provide the same resolution of pangolin lineages, and to explore if admixture might explain these differences, we applied sophisticated tests of introgression using > 2000 SNPs to investigate secondary gene flow between each of the three Sunda pangolin lineages. It is possible the admixture which we discovered is due to human-mediated movements of pangolins. Our findings impact a range of conservation actions, including tracing patterns of trade, repatriation of rescue animals, and conservation breeding. In order to conserve genetic diversity, we suggest that, pending further research, each pangolin lineage should as a precaution be protected and managed as an evolutionarily distinct conservation unit
Enhancing the efficacy of cytotoxic agents for cancer therapy using photochemical internalisation.
Photochemical internalisation (PCI) is a technique for improving cellular delivery of certain bioactive agents which are prone to sequestration within endolysosomes. There is a wide range of agents suitable for PCI-based delivery including toxins, oligonucleotides, genes and immunoconjugates which demonstrates the versatility of this technique. The basic mechanism of PCI involves triggering release of the agent from endolysosomes within the target cells using a photosensitiser which is selectively retained with the endolysosomal membranes. Excitation of the photosensitiser by visible light leads to disruption of the membranes via photooxidative damage thereby releasing the agent into the cytosol. This treatment enables the drugs to reach their intended subcellular target more efficiently and improves their efficacy. In this review we summarise the applications of this technique with the main emphasis placed on cancer chemotherapy
Pneumomediastinum and pneumothorax after orthognathic surgery -A case report-
The occurrences of pneumomediastinum and pneumothorax after oral and/or maxillofacial surgery are rare, but both are potentially life-threatening complications. Most of the cases that present pneumomediastinum and pneumothorax in the oral and/or maxillofacial surgery result from air dissecting down the fascial planes of the neck. We report a case of a 23-year-old male patient who underwent bilateral sagittal split ramus osteotomy under general anesthesia and developed pneumomediastinum and pneumothorax without any traumatic introduction of air through the cervical fascia three days postoperatively. The possible causes and its prevention are discussed with a review of the relevant literature
Intrusion detection routers: Design, implementation and evaluation using an experimental testbed
In this paper, we present the design, the implementation details, and the evaluation results of an intrusion detection and defense system for distributed denial-of-service (DDoS) attack. The evaluation is conducted using an experimental testbed. The system, known as intrusion detection router (IDR), is deployed on network routers to perform online detection on any DDoS attack event, and then react with defense mechanisms to mitigate the attack. The testbed is built up by a cluster of sufficient number of Linux machines to mimic a portion of the Internet. Using the testbed, we conduct real experiments to evaluate the IDR system and demonstrate that IDR is effective in protecting the network from various DDoS attacks. © 2006 IEEE.published_or_final_versio
Positive psychology of Malaysian students: impacts of engagement, motivation, self-compassion and wellbeing on mental health
Malaysia plays a key role in education of the Asia Pacific, expanding its scholarly output rapidly. However, mental health of Malaysian students is challenging, and their help-seeking is low because of stigma. This study explored the relationships between mental health and positive psychological constructs (academic engagement, motivation, self-compassion, and wellbeing), and evaluated the relative contribution of each positive psychological construct to mental health in Malaysian students. An opportunity sample of 153 students completed the measures regarding these constructs. Correlation, regression, and mediation analyses were conducted. Engagement, amotivation, self-compassion, and wellbeing were associated with, and predicted large variance in mental health. Self-compassion was the strongest independent predictor of mental health among all the positive psychological constructs. Findings can imply the strong links between mental health and positive psychology, especially selfcompassion. Moreover, intervention studies to examine the effects of self-compassion training on mental health of Malaysian students appear to be warranted.N/
Clofazimine Inhibits Human Kv1.3 Potassium Channel by Perturbing Calcium Oscillation in T Lymphocytes
The Kv1.3 potassium channel plays an essential role in effector memory T cells and has been implicated in several important autoimmune diseases including multiple sclerosis, psoriasis and type 1 diabetes. A number of potent small molecule inhibitors of Kv1.3 channel have been reported, some of which were found to be effective in various animal models of autoimmune diseases. We report herein the identification of clofazimine, a known anti-mycobacterial drug, as a novel inhibitor of human Kv1.3. Clofazimine was initially identified as an inhibitor of intracellular T cell receptor-mediated signaling leading to the transcriptional activation of human interleukin-2 gene in T cells from a screen of the Johns Hopkins Drug Library. A systematic mechanistic deconvolution revealed that clofazimine selectively blocked the Kv1.3 channel activity, perturbing the oscillation frequency of the calcium-release activated calcium channel, which in turn led to the inhibition of the calcineurin-NFAT signaling pathway. These effects of clofazimine provide the first line of experimental evidence in support of a causal relationship between Kv1.3 and calcium oscillation in human T cells. Furthermore, clofazimine was found to be effective in blocking human T cell-mediated skin graft rejection in an animal model in vivo. Together, these results suggest that clofazimine is a promising immunomodulatory drug candidate for treating a variety of autoimmune disorders
Increased expression of phosphorylated forms of RNA-dependent protein kinase and eukaryotic initiation factor 2α may signal skeletal muscle atrophy in weight-losing cancer patients
Previous studies suggest that the activation (autophosphorylation) of dsRNA-dependent protein kinase (PKR) can stimulate protein degradation, and depress protein synthesis in skeletal muscle through phosphorylation of the translation initiation factor 2 (eIF2) on the α-subunit. To understand whether these mediators are important in muscle wasting in cancer patients, levels of the phospho forms of PKR and eIF2α have been determined in rectus abdominus muscle of weight losing patients with oesophago-gastric cancer, in comparison with healthy controls. Levels of both phospho PKR and phospho eIF2α were significantly enhanced in muscle of cancer patients with weight loss irrespective of the amount and there was a linear relationship between phosphorylation of PKR and phosphorylation of eIF2α (correlation coefficient 0.76, P=0.005). This suggests that phosphorylation of PKR led to phosphorylation of eIF2α. Myosin levels decreased as the weight loss increased, and there was a linear relationship between myosin expression and the extent of phosphorylation of eIF2α (correlation coefficient 0.77, P=0.004). These results suggest that phosphorylation of PKR may be an important initiator of muscle wasting in cancer patients
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