The biosynthesis of the tropane alkaloid hyoscyamine in datura stramonium

This thesis investigates the biosynthesis of the tropane alkaloid hyoscyamine in Datura stramonium. The biosynthesis of the medicinally important tropane alkaloid hyoscyamine has been investigated for many years. However, the complete biosynthetic pathway is still to be unravelled. This thesis concentrates primarily on the last step of hyoscyamine biosynthesis - the rearrangement of littorine to hyoscyamine. In Chapter 1, an introduction to the biosynthesis of hyoscyamine and other related alkaloids is discussed. In Chapter 2, (^18)O-labelling studies are utilised in order to probe the nature of the rearrangement. The results reveal that intriguingly that the rearrangement is uidirect and perhaps involves an aldehyde intermediate, which requires to be reduced by a dehydrogenase to furnish hyoscyamine. In Chapter 3, aryl substituted fluorophenyllactates were used in order to probe the mechanism of the rearrangement of littorine to hyoscyamine. The working hypothesis suggests the involvement of a carbocation uitermediate following literature reports on chemical and enzymatic models. The results reveal that the mechanism of the rearrangement is not as clear cut as predicted, and that perhaps binding affinities to the littorine synthase and littorine mutase affect the efficiency of the rearrangement. In Chapter 4, attention turned back to the tropane moiety of hyoscyamine. Its biosynthesis has been thoroughly investigated although there still remains the mystery as to how acetate units are condensed with the N-methylpyrrolinium salt to generate the bicyclic tropane ring

Meta-analysis of preclinical studies of mesenchymal stromal cells to treat rheumatoid arthritis.

BackgroundThis study aims to evaluate the quality of preclinical data, determine the effect sizes, and identify experimental measures that inform efficacy using mesenchymal stromal (or stem) cells (MSC) therapy in animal models of rheumatoid arthritis (RA).MethodsLiterature searches were performed on MSC preclinical studies to treat RA. MSC treatment effect sizes were determined by the most commonly used outcome measures, including paw thickness, clinical score, and histological score.FindingsA total of 48 studies and 94 treatment arms were included, among which 42 studies and 79 treatment arms reported that MSC improved outcomes. The effect sizes of RA treatments using MSC, when compared to the controls, were: paw thickness was ameliorated by 53.6% (95% confidence interval (CI): 26.7% -80.4%), histological score was decreased by 44.9% (95% CI: 33.3% -56.6%), and clinical score was decreased by 29.9% (95% CI: 16.7% -43.0%). Specifically, our results indicated that human umbilical cord derived MSC led to large improvements of the clinical score (-42.1%) and histological score (-51.4%).InterpretationTo the best of our knowledge, this meta-analysis is to quantitatively answer whether MSC represent a robust RA treatment in animal models. It suggests that in preclinical studies, MSC have consistently exhibited therapeutic benefits. The findings demonstrate a need for considering variations in different animal models and treatment protocols in future studies using MSC to treat RA in humans to maximise the therapeutic gains in the era of precision medicine.FundsNIH [1DP2CA195763], Baylx Inc.: BI-206512, NINDS/NIH Training Grant [Award# NS082174]

Graft Suturing for Lenticule Dislocation after Descemet Stripping Automated Endothelial Keratoplasty

Purpose: To report the mid-term outcomes of graft suturing in a patient with lenticule dislocation after Descemet stripping automated endothelial keratoplasty (DSAEK). Case Report: A 78-year old woman was found to have graft dislocation involving the nasal half of the cornea after uneventful DSAEK. Graft repositioning, refilling the anterior chamber with air, and placement of four full-thickness 10/0 nylon sutures over the detached area were performed two weeks after the initial surgery. The sutures were removed 6 weeks later. Serial specular microscopy and anterior segment optical coherence tomography were performed. At 18 months, there was good lenticule apposition and a clear graft. Conclusion: Anchoring sutures seem to be effective for management of graft detachment following DSAEK

Constraints on millicharged particles with low threshold germanium detectors at Kuo-Sheng Reactor Neutrino Laboratory

Relativistic millicharged particles ($\chi_q$) have been proposed in various extensions to the Standard Model of particle physics. We consider the scenarios where they are produced at nuclear reactor core and via interactions of cosmic-rays with the earth's atmosphere. Millicharged particles could also be candidates for dark matter, and become relativistic through acceleration by supernova explosion shock waves. The atomic ionization cross section of $\chi_q$ with matter are derived with the equivalent photon approximation. Smoking-gun signatures with significant enhancement in the differential cross section are identified. New limits on the mass and charge of $\chi_q$ are derived, using data taken with a point-contact germanium detector with 500g mass functioning at an energy threshold of 300~eV at the Kuo-Sheng Reactor Neutrino Laboratory.Comment: 8 pages, 7 figure

SOAP3-dp: Fast, Accurate and Sensitive GPU-based Short Read Aligner

To tackle the exponentially increasing throughput of Next-Generation Sequencing (NGS), most of the existing short-read aligners can be configured to favor speed in trade of accuracy and sensitivity. SOAP3-dp, through leveraging the computational power of both CPU and GPU with optimized algorithms, delivers high speed and sensitivity simultaneously. Compared with widely adopted aligners including BWA, Bowtie2, SeqAlto, GEM and GPU-based aligners including BarraCUDA and CUSHAW, SOAP3-dp is two to tens of times faster, while maintaining the highest sensitivity and lowest false discovery rate (FDR) on Illumina reads with different lengths. Transcending its predecessor SOAP3, which does not allow gapped alignment, SOAP3-dp by default tolerates alignment similarity as low as 60 percent. Real data evaluation using human genome demonstrates SOAP3-dp's power to enable more authentic variants and longer Indels to be discovered. Fosmid sequencing shows a 9.1 percent FDR on newly discovered deletions. SOAP3-dp natively supports BAM file format and provides a scoring scheme same as BWA, which enables it to be integrated into existing analysis pipelines. SOAP3-dp has been deployed on Amazon-EC2, NIH-Biowulf and Tianhe-1A.Comment: 21 pages, 6 figures, submitted to PLoS ONE, additional files available at "https://www.dropbox.com/sh/bhclhxpoiubh371/O5CO_CkXQE". Comments most welcom

Evaluation of the risk of cardiovascular events with clarithromycin using both propensity score and self-controlled study designs

Aim: Some previous studies suggest a long term association between clarithromycin use and cardiovascular events. This study investigates this association for clarithromycin given as part of Helicobacter pylori treatment (HPT). Methods: Our source population was the Clinical Practice Research Datalink (CPRD), a UK primary care database. We conducted a self-controlled case series (SCCS), a case–time–control study (CTC) and a propensity score adjusted cohort study comparing the rate of cardiovascular events in the 3 years after exposure to HPT containing clarithromycin with exposure to clarithromycin free HPT. Outcomes were first incident diagnosis of myocardial infarction (MI), arrhythmia and stroke. For the cohort analysis we included secondary outcomes all cause and cardiovascular mortality. Results: Twenty-eight thousand five hundred and fifty-two patients were included in the cohort. The incidence rate ratio of first MI within 1 year of exposure to HPT containing clarithromycin was 1.07 (95% CI 0.85, 1.34, P = 0.58) and within 90 days was 1.43 (95% CI 0.99, 2.09 P = 0.057) in the SCCS analysis. CTC and cohort results were consistent with these findings. Conclusions There was some evidence for a short term association for first MI but none for a long term association for any outcome

Estimating the financial impact of gene therapy in the U.S.

We empirically assess the potential financial impact of future gene therapies on the US economy. After identifying 109 late-stage gene therapy clinical trials currently underway, we estimate the number of new and existing patients with corresponding diseases to be treated by these gene therapies, developing and applying novel mathematical models to estimate the increase in quality-adjusted life years for each approved gene therapy. We then simulate the launch prices and the expected spending for these therapies over a 15-year time horizon. Under conservative assumptions, the results of our simulation suggest that an expected total of 1.09 million patients will be treated by gene therapy from January 2020 to December 2034. The expected peak annual spending on these therapies is $25.3 billion, and the expected total spending from January 2020 to December 2034 is$306 billion. Assuming a linear pace of future gene therapy development fitted to past experience, our spending estimate increases by only 15.7% under conservative assumptions. As a proxy for the impact of expected spending on different public and private payers, we decompose the estimated annual spending by treated age group. Since experience suggests that insurers with annual budget constraints may restrict access to therapies with expected benefit to the patient, we consider various methods of payment to ensure access to these therapies even among those insured by the most budget-constrained payers.https://www.nber.org/papers/w28628First author draf

Foreign language learning as potential treatment for mild cognitive impairment

As the number of older adults increases, age-related health issues (both physical and cognitive) and associated costs are expected to increase, placing emotional and financial stress on family members and the health system. Dementia is one of the most devastating and costly diseases that older adults face. The present study aimed to determine whether foreign language learning can improve cognitive outcomes of older adults with mild cognitive impairment (MCI). The objectives are to determine whether foreign language learning is (1) effective in boosting cognitive reserve and promoting healthy cognitive function and (2) superior to other established cognitively stimulating activities such as crossword and logic puzzles

Renal screening in children after exposure to low dose melamine in Hong Kong: cross sectional study

Objective To investigate the renal outcomes of children after exposure to low dose melamine in Hong Kong