The role of Epidermal Growth Factor Receptor (ErbB1) in axon regeneration

The thesis describes experiments on the role of Epidermal Growth Factor receptor (ErbB1) in limiting axonal regeneration. Pharmacological inhibitors of ErbB1 are known to improve neurite outgrowth from neurons grown in vitro on various inhibitory substrates such as CNS myelin, chondroitin sulphate proteoglycans (CSPGs) and fibrinogen (Koprivica et al., 2005). However, the hypothesis that ErbB1 is involved in the signalling mechanisms from various CNS inhibitory molecules has been challenged in papers form the Logan laboratory (Ahmed et al., 2010) which concluded that pharmacological blockers disinhibit neurite outgrowth by acting off-target to ErbB1. The first stage of this project was to use primary sensory neurons from ErbB1 knockout mice to test the hypothesis that ErbB1 is involved in inhibition of neurite outgrowth in vitro in the presence of CNS myelin, a Toll-Like Receptor 3 ligand (Poly I:C) and CSPGs. Through a series of experiments that have been described in this thesis, it was shown that ErbB1 antagonists act on-target and that ErbB1 signalling causes inhibition of neurite outgrowth of neurons cultured in the presence of Poly I:C, CNS myelin or CSPGs. Moreover, buffering calcium was shown to abolish the inhibitory effects caused by ErbB1 signalling, indicating that calcium is essential for the activation of the receptor. Other molecules that may be associated with ErbB1 signalling leading to inhibition of neurite outgrowth include PTEN and novel Sulfatase enzymes- Sulf1 and Sulf2. Using immunohistochemistry, Sulf1 and Sulf2 were shown to be expressed by a large variety of neurons. Also, ErbB1 expression detected immunohistochemically was predominantly localised to neurons. The thesis also describes preliminary observations on the efficacy of an ErbB1 antagonist or a dominant-negative ErbB1 lentivirus in improving axonal regeneration following an optic nerve crush or spinal cord injury in adult rats. In conclusion, ErbB1 signalling following injury is associated with regeneration failure

Isolation of Diterpenoids from Jatropha podagrica against Hepatitis C virus

One new lathyrane diterpenoid, Jatropodagrene (1) along with three known compounds have been isolated from the root bark of Jatropha podagrica. The structure of the new compound was established from its 1D and 2D NMR spectra and in comparison with data reported in previous literatures. Compound 1 was highly cytotoxic (98.86% inhibition) to the HCV virus, while compounds 2 (EC50, EC90, CC50 5.8, 33.1, 22.6 μg/mL, respectively) and 3 displayed significant anti HCV activity. This is the first report of the anti hepatitis C virus activity of lathyrane skeleton and J. podagrica.Keywords: Jatropha podagrica; medicinal plant; hepatitis C virus; extract; pure compound

Mycolactone-dependent depletion of endothelial cell thrombomodulin is strongly associated with fibrin deposition in Buruli ulcer lesions

A well-known histopathological feature of diseased skin in Buruli ulcer (BU) is coagulative necrosis caused by the Mycobacterium ulcerans macrolide exotoxin mycolactone. Since the underlying mechanism is not known, we have investigated the effect of mycolactone on endothelial cells, focussing on the expression of surface anticoagulant molecules involved in the protein C anticoagulant pathway. Congenital deficiencies in this natural anticoagulant pathway are known to induce thrombotic complications such as purpura fulimans and spontaneous necrosis. Mycolactone profoundly decreased thrombomodulin (TM) expression on the surface of human dermal microvascular endothelial cells (HDMVEC) at doses as low as 2ng/ml and as early as 8hrs after exposure. TM activates protein C by altering thrombin's substrate specificity, and exposure of HDMVEC to mycolactone for 24 hours resulted in an almost complete loss of the cells' ability to produce activated protein C. Loss of TM was shown to be due to a previously described mechanism involving mycolactone-dependent blockade of Sec61 translocation that results in proteasome-dependent degradation of newly synthesised ER-transiting proteins. Indeed, depletion from cells determined by live-cell imaging of cells stably expressing a recombinant TM-GFP fusion protein occurred at the known turnover rate. In order to determine the relevance of these findings to BU disease, immunohistochemistry of punch biopsies from 40 BU lesions (31 ulcers, nine plaques) was performed. TM abundance was profoundly reduced in the subcutis of 78% of biopsies. Furthermore, it was confirmed that fibrin deposition is a common feature of BU lesions, particularly in the necrotic areas. These findings indicate that there is decreased ability to control thrombin generation in BU skin. Mycolactone's effects on normal endothelial cell function, including its ability to activate the protein C anticoagulant pathway are strongly associated with this. Fibrin-driven tisischemia could contribute to the development of the tissue necrosis seen in BU lesions

Reproductive health and quality of life of young Burmese refugees in Thailand

BACKGROUND: Of the 140,000 Burmese* refugees living in camps in Thailand, 30% are youths aged 15-24. Health services in these camps do not specifically target young people and their problems and needs are poorly understood. This study aimed to assess their reproductive health issues and quality of life, and identifies appropriate service needs. METHODS: We used a stratified two-stage random sample questionnaire survey of 397 young people 15-24 years from 5,183 households, and 19 semi-structured qualitative interviews to assess and explore health and quality of life issues. RESULTS: The young people in the camps had very limited knowledge of reproductive health issues; only about one in five correctly answered at least one question on reproductive health. They were clear that they wanted more reproductive health education and services, to be provided by health workers rather than parents or teachers who were not able to give them the information they needed. Marital status was associated with sexual health knowledge; having relevant knowledge of reproductive health was up to six times higher in married compared to unmarried youth, after adjusting for socio-economic and demographic factors. Although condom use was considered important, in practice a large proportion of respondents felt too embarrassed to use them. There was a contradiction between moral views and actual behaviour; more than half believed they should remain virgins until marriage, while over half of the youth experienced sex before marriage. Two thirds of women were married before the age of 18, but two third felt they did not marry at the right age. Forced sex was considered acceptable by one in three youth. The youth considered their quality of life to be poor and limited due to confinement in the camps, the limited work opportunities, the aid dependency, the unclear future and the boredom and unhappiness they face. CONCLUSIONS: The long conflict in Myanmar and the resultant long stay in refugee camps over decades affect the wellbeing of these young people. Lack of sexual health education and relevant services, and their concerns for their future are particular problems, which need to be addressed. Issues of education, vocational training and job possibilities also need to be considered.*Burmese is used for all ethnic groups

Irish general practitioner attitudes toward decriminalisation and medical use of cannabis: results from a national survey.

BACKGROUND: Governmental debate in Ireland on the de facto decriminalisation of cannabis and legalisation for medical use is ongoing. A cannabis-based medicinal product (Sativex®) has recently been granted market authorisation in Ireland. This unique study aimed to investigate Irish general practitioner (GP) attitudes toward decriminalisation of cannabis and assess levels of support for use of cannabis for therapeutic purposes (CTP). METHODS: General practitioners in the Irish College of General Practitioner (ICGP) database were invited to complete an online survey. Anonymous data yielded descriptive statistics (frequencies, percentages) to summarise participant demographic information and agreement with attitudinal statements. Chi-square tests and multi-nominal logistic regression were included. RESULTS: The response rate was 15% (n = 565) which is similar to other Irish national GP attitudinal surveys. Over half of Irish GPs did not support the decriminalisation of cannabis (56.8%). In terms of gender, a significantly higher proportion of males compared with females (40.6 vs. 15%; p < 0.0001) agreed or strongly agreed with this drug policy approach. A higher percentage of GPs with advanced addiction specialist training (level 2) agreed/strongly agreed that cannabis should be decriminalised (54.1 vs. 31.5%; p = 0.021). Over 80% of both genders supported the view that cannabis use has a significant effect on patients' mental health and increases the risk of schizophrenia (77.3%). Over half of Irish GPs supported the legalisation of cannabis for medical use (58.6%). A higher percentage of those who were level 1-trained (trained in addiction treatment but not to an advanced level) agreed/strongly agreed cannabis should be legalised for medical use (p = 0.003). Over 60% agreed that cannabis can have a role in palliative care, pain management and treatment of multiple sclerosis (MS). In the regression response predicator analysis, females were 66.2% less likely to agree that cannabis should be decriminalised, 42.5% less likely to agree that cannabis should be legalised for medical use and 59.8 and 37.6% less likely to agree that cannabis has a role in palliative care and in the treatment of multiple sclerosis (respectively) than males. CONCLUSIONS: The majority of Irish GPs do not support the present Irish governmental drug policy of decriminalisation of cannabis but do support the legalisation of cannabis for therapeutic purposes. Male GPs and those with higher levels of addiction training are more likely to support a more liberal drug policy approach to cannabis for personal use. A clear majority of GPs expressed significant concerns regarding both the mental and physical health risks of cannabis use. Ongoing research into the health and other effects of drug policy changes on cannabis use is required

Ancestral Mutation in Telomerase Causes Defects in Repeat Addition Processivity and Manifests As Familial Pulmonary Fibrosis

The telomerase reverse transcriptase synthesizes new telomeres onto chromosome ends by copying from a short template within its integral RNA component. During telomere synthesis, telomerase adds multiple short DNA repeats successively, a property known as repeat addition processivity. However, the consequences of defects in processivity on telomere length maintenance are not fully known. Germline mutations in telomerase cause haploinsufficiency in syndromes of telomere shortening, which most commonly manifest in the age-related disease idiopathic pulmonary fibrosis. We identified two pulmonary fibrosis families that share two non-synonymous substitutions in the catalytic domain of the telomerase reverse transcriptase gene hTERT: V791I and V867M. The two variants fell on the same hTERT allele and were associated with telomere shortening. Genealogy suggested that the pedigrees shared a single ancestor from the nineteenth century, and genetic studies confirmed the two families had a common founder. Functional studies indicated that, although the double mutant did not dramatically affect first repeat addition, hTERT V791I-V867M showed severe defects in telomere repeat addition processivity in vitro. Our data identify an ancestral mutation in telomerase with a novel loss-of-function mechanism. They indicate that telomere repeat addition processivity is a critical determinant of telomere length and telomere-mediated disease

The Origins of African Plasmodium vivax; Insights from Mitochondrial Genome Sequencing

Plasmodium vivax, the second most prevalent of the human malaria parasites, is estimated to affect 75 million people annually. It is very rare, however, in west and central Africa, due to the high prevalence of the Duffy negative phenotype in the human population. Due to its rarity in Africa, previous studies on the phylogeny of world-wide P. vivax have suffered from insufficient samples of African parasites. Here we compare the mitochondrial sequence diversity of parasites from Africa with those from other areas of the world, in order to investigate the origin of present-day African P. vivax. Mitochondrial genome sequencing revealed relatively little polymorphism within the African population compared to parasites from the rest of the world. This, combined with sequence similarity with parasites from India, suggests that the present day African P. vivax population in humans may have been introduced relatively recently from the Indian subcontinent. Haplotype network analysis also raises the possibility that parasites currently found in Africa and South America may be the closest extant relatives of the ancestors of the current world population. Lines of evidence are adduced that this ancestral population may be from an ancient stock of P. vivax in Africa

Randomized Controlled Trials of HIV/AIDS Prevention and Treatment in Africa: Results from the Cochrane HIV/AIDS Specialized Register

INTRODUCTION: To effectively address HIV/AIDS in Africa, evidence on preventing new infections and providing effective treatment is needed. Ideally, decisions on which interventions are effective should be based on evidence from randomized controlled trials (RCTs). Our previous research described African RCTs of HIV/AIDS reported between 1987 and 2003. This study updates that analysis with RCTs published between 2004 and 2008. OBJECTIVES: To describe RCTs of HIV/AIDS conducted in Africa and reported between 2004 and 2008. METHODS: We searched the Cochrane HIV/AIDS Specialized Register in September 2009. Two researchers independently evaluated studies for inclusion and extracted data using standardized forms. Details included location of trials, interventions, methodological quality, location of principal investigators and funders. RESULTS: Our search identified 834 RCTs, with 68 conducted in Africa. Forty-three assessed prevention-interventions and 25 treatment-interventions. Fifteen of the 43 prevention RCTs focused on preventing mother-to-child HIV transmission. Thirteen of the 25 treatment trials focused on opportunistic infections. Trials were conducted in 16 countries with most in South Africa (20), Zambia (12) and Zimbabwe (9). The median sample size was 628 (range 33-9645). Methods used for the generation of the allocation sequence and allocation concealment were adequate in 38 and 32 trials, respectively, and 58 reports included a CONSORT recommended flow diagram. Twenty-nine principal investigators resided in the United States of America (USA) and 18 were from African countries. Trials were co-funded by different agencies with most of the funding obtained from USA governmental and non-governmental agencies. Nineteen pharmaceutical companies provided partial funding to 15 RCTs and African agencies co-funded 17 RCTs. Ethical approval was reported in 65 trials and informed consent in 61 trials. CONCLUSION: Prevention trials dominate the trial landscape in Africa. Of note, few principal investigators and funders are from Africa. These findings mirror our previous work and continue to indicate a need for strengthening trial research capacity in Africa

Effect of genetic testing for risk of type 2 diabetes mellitus on health behaviors and outcomes: study rationale, development and design

<p>Abstract</p> <p>Background</p> <p>Type 2 diabetes is a prevalent chronic condition globally that results in extensive morbidity, decreased quality of life, and increased health services utilization. Lifestyle changes can prevent the development of diabetes, but require patient engagement. Genetic risk testing might represent a new tool to increase patients' motivation for lifestyle changes. Here we describe the rationale, development, and design of a randomized controlled trial (RCT) assessing the clinical and personal utility of incorporating type 2 diabetes genetic risk testing into comprehensive diabetes risk assessments performed in a primary care setting.</p> <p>Methods/Design</p> <p>Patients are recruited in the laboratory waiting areas of two primary care clinics and enrolled into one of three study arms. Those interested in genetic risk testing are randomized to receive <it>either </it>a standard risk assessment (SRA) for type 2 diabetes incorporating conventional risk factors plus upfront disclosure of the results of genetic risk testing ("SRA+G" arm), <it>or </it>the SRA alone ("SRA" arm). Participants not interested in genetic risk testing will not receive the test, but will receive SRA (forming a third, "no-test" arm). Risk counseling is provided by clinic staff (not study staff external to the clinic). Fasting plasma glucose, insulin levels, body mass index (BMI), and waist circumference are measured at baseline and 12 months, as are patients' self-reported behavioral and emotional responses to diabetes risk information. Primary outcomes are changes in insulin resistance and BMI after 12 months; secondary outcomes include changes in diet patterns, physical activity, waist circumference, and perceived risk of developing diabetes.</p> <p>Discussion</p> <p>The utility, feasibility, and efficacy of providing patients with genetic risk information for common chronic diseases in primary care remain unknown. The study described here will help to establish whether providing type 2 diabetes genetic risk information in a primary care setting can help improve patients' clinical outcomes, risk perceptions, and/or their engagement in healthy behavior change. In addition, study design features such as the use of existing clinic personnel for risk counseling could inform the future development and implementation of care models for the use of individual genetic risk information in primary care.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00849563">NCT00849563</a></p