Metabolic engineering approaches to biosynthesize terpenoids in Saccharomyces cerevisiae

Terpenoids are the largest class of natural products and are typically isolated from natural sources. However, heterologous expression of terpene synthases in microbial hosts such as E. coli or Saccharomyces cerevisiae has become an attractive alternative. S. cerevisiae has an intact sterol biosynthetic pathway, and many of the intermediates also serve as precursors for terpene synthases. Metabolic engineering efforts focus on optimizing product yields through increasing carbon flux through the desired pathway, removing competing enzymes, or altering enzymatic activity. This work describes the metabolic engineering of S. cerevisiae to enhance terpene production by exploiting these three approaches. Diterpene synthases were expressed in a yeast strain previously reported to accumulate the diterpene precursor geranylgeranyl pyrophosphate (GGPP). The strains produced milligram amounts of GGPP hydrolysis products geranylgeraniol and geranyllinalool, as well as the GGPP cyclization products ent -copalyl pyrophosphate, ent-kaurene, and abietadiene. Because diterpene production is limited by transit peptides targeting diterpene synthases into plastids, protein expression was increased by co-expressing a chloroplast processing enzyme in two different diterpene-producing strains. The in vivo-generated mature diterpene synthases functioned more effectively, thereby increasing cyclization yield. This thesis also describes a new method for controlling farnesyl pyrophosphate (FPP) hydrolysis product profile by adjusting media pH. Hydrolysis was found to be partially controlled by a phosphatase DPP1, however a majority of FPP hydrolysis is non-enzymatic. In a squalene synthase deletion strain, FPP accumulates and hydrolyzes readily to farnesol and nerolidol, and the ratios of these products are determined by the pH of the media. Finally, a yeast strain was constructed to increase production of the 30-carbon triterpene precursors oxidosqualene (OS) and dioxidosqualene (DOS) by over-expressing the sterol biosynthesis rate-limiting enzyme 3-hydroxy-3-methylglutaryl CoA reductase (HMG1) in a lanosterol synthase deletion background. This strain accumulated twenty times more OS and DOS than the strain with only the native HMG1. Over-expression of squalene epoxidase (ERG1) in a lanosterol synthase background greatly enhanced the levels of DOS compared to OS

Challenges to access and provision of palliative care for people who are homeless : a systematic review of qualitative research

Background: People who are homeless or vulnerably housed are a marginalized group who often experience high rates of morbidity and die young as a result of complex problems. Access to health care and support can be challenging, with access to palliative care even more so. This review presents a synthesis of published qualitative research exploring from the perspective of homeless people and those working to support them, current challenges to palliative care access and provision, in addition to suggestions for what may improve palliative care for this population. Methods: Systematic review of qualitative research analysed using thematic synthesis. PsycINFO, Medline, Sociological Abstracts, Social Services Abstracts, Science citations index and CINAHL were searched up to September 2016. Thematic synthesis involved a three-step inductive process to develop a deeper understanding of the challenges to and suggestions for the access and provision of palliative care for homeless people. Results: Thirteen qualitative articles, reporting nine studies were identified. The challenges to access and provision to palliative care were drawn from the data covering three broad areas, namely “the chaotic lifestyles sometimes associated with being homeless”, “the delivery of palliative care within a hostel for homeless people” and provision within “mainstream health care systems”. Obstacles were related to homeless persons competing day-to-day priorities, their experience of stigma in mainstream settings, the high burden on hostel staff in supporting residents at the end of life and inflexibility in mainstream health care systems. Suggestions for improving access to palliative care include building trust between homeless persons and health professionals, increasing collaboration between and flexibility within services, and providing more training and support for all professionals. Conclusions: The provision of palliative care can be complicated for all populations, however delivering palliative care for people who are homeless is influenced by a potentially greater and more varied range of factors, on both individual and systemic levels, than providing palliative care for the housed population. Careful consideration and potentially great changes will be needed within health care systems to ensure homeless populations have equitable access to palliative care

Absolute risk representation in cardiovascular disease prevention: comprehension and preferences of health care consumers and general practitioners involved in a focus group study

Background Communicating risk is part of primary prevention of coronary heart disease and stroke, collectively referred to as cardiovascular disease (CVD). In Australia, health organisations have promoted an absolute risk approach, thereby raising the question of suitable standardised formats for risk communication. Methods Sixteen formats of risk representation were prepared including statements, icons, graphical formats, alone or in combination, and with variable use of colours. All presented the same risk, i.e., the absolute risk for a 55 year old woman, 16% risk of CVD in five years. Preferences for a five or ten-year timeframe were explored. Australian GPs and consumers were recruited for participation in focus groups, with the data analysed thematically and preferred formats tallied. Results Three focus groups with health consumers and three with GPs were held, involving 19 consumers and 18 GPs. Consumers and GPs had similar views on which formats were more easily comprehended and which conveyed 16% risk as a high risk. A simple summation of preferences resulted in three graphical formats (thermometers, vertical bar chart) and one statement format as the top choices. The use of colour to distinguish risk (red, yellow, green) and comparative information (age, sex, smoking status) were important ingredients. Consumers found formats which combined information helpful, such as colour, effect of changing behaviour on risk, or comparison with a healthy older person. GPs preferred formats that helped them relate the information about risk of CVD to their patients, and could be used to motivate patients to change behaviour. Several formats were reported as confusing, such as a percentage risk with no contextual information, line graphs, and icons, particularly those with larger numbers. Whilst consumers and GPs shared preferences, the use of one format for all situations was not recommended. Overall, people across groups felt that risk expressed over five years was preferable to a ten-year risk, the latter being too remote. Conclusions Consumers and GPs shared preferences for risk representation formats. Both groups liked the option to combine formats and tailor the risk information to reflect a specific individual's risk, to maximise understanding and provide a good basis for discussion

Genome-wide association study of colorectal cancer identifies six new susceptibility loci

El document inclou una pàgina final amb una correcció (corrigendum). Aquesta, per si sola, té el següent DOI: 10.1038/ncomms9739 i es va publicar al mateix vol. 6.Genetic susceptibility to colorectal cancer is caused by rare pathogenic mutations and common genetic variants that contribute to familial risk. Here we report the results of a two-stage association study with 18,299 cases of colorectal cancer and 19,656 controls, with follow-up of the most statistically significant genetic loci in 4,725 cases and 9,969 controls from two Asian consortia. We describe six new susceptibility loci reaching a genome-wide threshold of P<5.0E-08. These findings provide additional insight into the underlying biological mechanisms of colorectal cancer and demonstrate the scientific value of large consortia-based genetic epidemiology studies

Novel measures of cardiovascular health and its association with prevalence and progression of age-related macular degeneration: the CHARM study

<p>Abstract</p> <p>Background</p> <p>To determine if novel measures of cardiovascular health are associated with prevalence or progression of age-related macular degeneration (AMD).</p> <p>Methods</p> <p>Measures of the cardiovascular system: included intima media thickness (IMT), pulse wave velocity (PWV), systemic arterial compliance (SAC), carotid augmentation index (AI). For the prevalence study, hospital-based AMD cases and population-based age- and gender-matched controls with no signs of AMD in either eye were enrolled. For the progression component, participants with early AMD were recruited from two previous studies; cases were defined as progression in one or both eyes and controls were defined as no progression in either eye.</p> <p>Results</p> <p>160 cases and 160 controls were included in the prevalence component. The upper two quartiles of SAC, implying good cardiovascular health, were significantly associated with increased risk of AMD (OR = 2.54, 95% CL = 1.29, 4.99). High PWV was associated with increased prevalent AMD. Progression was observed in 82 (32.3%) of the 254 subjects recruited for the progression component. Higher AI (worse cardiovascular function) was protective for AMD progression (OR = 0.30, 95%CL = 0.13, 0.69). Higher aortic PWV was associated with increased risk of AMD progression; the highest risk was seen with the second lowest velocity (OR = 6.22, 95% CL = 2.35, 16.46).</p> <p>Conclusion</p> <p>The results were unexpected in that better cardiovascular health was associated with increased risk of prevalent AMD and progression. Inconsistent findings between the prevalence and progression components could be due to truly different disease etiologies or to spurious findings, as can occur with inherent biases in case control studies of prevalence. Further investigation of these non-invasive methods of characterizing the cardiovascular system should be undertaken as they may help to further elucidate the role of the cardiovascular system in the etiology of prevalent AMD and progression.</p

Associations with drug use and sexualised drug use among women who have sex with women (WSW) in the UK: Findings from the LGBT Sex and Lifestyles Survey

Introduction Studies indicate that women who have sex with women (WSW) report greater levels of drug use than heterosexual women, but globally few studies have looked at sexualised drug use among WSW. This study investigated the factors associated with drug use and sexualised drug use (SDU) among WSW. Methods Potential participants across the UK were invited to take part in a cross-sectional anonymous online survey between April-June 2018. The LGBT Sex and Lifestyles Survey recruited participants through Facebook advertising and social media posts from community organisations. Multivariate logistic regression was used to compare WSW who had engaged in any drug use in the past 12 months with those who had not, and those who engaged in sexualised drug use in the past 12 months with those who engaged in other drug use. Results: 1501 WSW could be included in the analyses (mean age = 28.9, 97% white ethnicity). Any drug use was reported by 39% of WSW (n = 583), 44% of which (17% of total, n = 258) reported SDU. Factors associated with drug use were identifying as queer (aOR = 1.86, 95%CI 1.08, 3.23), younger age (aOR = 0.96, 95%CI 0.95, 0.98), being born outside the UK (aOR = 1.75, 95%CI 1.15, 2.66), recent sexual assault (aOR = 2.35, 95%CI 1.43, 3.86), > = 5 female sexual partners (aOR = 3.81, 95%CI 1.81, 8.01), and psychological distress (aOR = 1.75, 95%CI 1.15, 2.67). SDU was associated with identifying as bisexual (aOR = 2.55, 95%CI 1.69, 3.86), > = 5 female sexual partners (aOR = 4.50, 95%CI 1.91, 10.59), and highest education achieved at 16 or lower (aOR = 2.46, 95%CI 1.24, 4.90). Conclusions: Some WSW may have negative experiences in relation to drug use and SDU. Harm reduction and health services that provide services for WSW should be aware of potentially compounding factors related to drug use, such as sexual assault and psychological distress, providing a safe and LGBT-friendly environment to discuss these issues

Medical conditions at enrollment do not impact efficacy and safety of the adjuvanted recombinant zoster vaccine:a pooled post-hoc analysis of two parallel randomized trials

In two pivotal efficacy studies (ZOE-50; ZOE-70), the adjuvanted recombinant zoster vaccine (RZV) demonstrated >90% efficacy against herpes zoster (HZ). Adults aged ≥50 or ≥70 years (ZOE-50 [NCT01165177]; ZOE-70 [NCT01165229]) were randomized to receive 2 doses of RZV or placebo 2 months apart. Vaccine efficacy and safety were evaluated post-hoc in the pooled (ZOE-50/70) population according to the number and type of selected medical conditions present at enrollment. At enrollment, 82.3% of RZV and 82.7% of placebo recipients reported ≥1 of the 15 selected medical conditions. Efficacy against HZ ranged from 84.5% (95% Confidence Interval [CI]: 46.4–97.1) in participants with respiratory disorders to 97.0% (95%CI: 82.3–99.9) in those with coronary heart disease. Moreover, efficacy remained >90% irrespective of the number of selected medical conditions reported by a participant. As indicated by the similarity of the point estimates, this post-hoc analysis suggests that RZV efficacy remains high in all selected medical conditions, as well as with increasing number of medical conditions. No safety concern was identified by the type or number of medical conditions present at enrollment

Deciphering colorectal cancer genetics through multi-omic analysis of 100,204 cases and 154,587 controls of European and east Asian ancestries

In the version of this article initially published, the author affiliations incorrectly listed “Candiolo Cancer Institute FPO-IRCCS, Candiolo (TO), Italy” as “Candiolo Cancer Institute, Candiolo, Italy.” The change has been made to the HTML and PDF versions of the article