Development of gene therapy for the treatment of retinal dystrophies caused by mutations in AIPL1

Genetic defects in AIPL1 cause a heterogeneous set of clinical conditions depending on the severity of the mutant alleles. Diseases can range from Leber Congenital Amaurosis (LCA), the severest form of early-onset retinal degeneration, to milder forms such as retinitis pigmentosa (RP) and cone-rod dystrophy. There is currently no effective treatment for LCA and inherited retinal dystrophies, which are the commonest cause of childhood blindness. AIPL1 is expressed primarily in retinal photoreceptors and is required for the biosynthesis of photoreceptor phosphodiesterase (PDE). This thesis describes a programme of work that examines the potential and efficacy of gene replacement therapy in the treatment of AIPL1- associated retinal diseases. It centres on the use of recombinant adeno-associated virus for the transfer of murine and human AIPL1 cDNA into photoreceptor cells. AAV-mediated gene replacement was assessed in two genetically engineered mouse models carrying null and hypomorphic alleles, Aipl1 -/- and Aipl1 h/h mice, which simulate retinal degenerations similar to human LCA and RP respectively. Three different rates of photoreceptor degeneration were simulated using the mouse models. To treat the different rates of degeneration, two pseudotypes of AAV (serotype 2 and 8) exhibiting different transduction kinetics were used for gene transfer. Substantial and long term rescue of the disease phenotype was seen as a result of Aipl1 transgene expression mediated by AAV2/2 vector in Aipl1 h/h mice and by AAV2/8 in rapid degenerations in light accelerated Aipl1 h/h mice and in Aipl1 -/- mice. Thus, the results presented in this thesis validates the efficacy of AIPL1 gene replacement using AAV vectors in varying rates of degeneration that reflected the clinical spectrum of disease. This is the first study to report long-term rescue of a photoreceptor-specific defect and to demonstrate effective rescue of rapid photoreceptor degeneration. The development of an efficient therapy depends on the identification of patients and characterisation of disease phenotype. A panel of DNA samples from patients with LCA and early onset severe retinal dystrophy was screened for mutations in the AIPL1 gene. Patients identified with AIPL1- associated disease demonstrated varying severity of disease from LCA to milder form of rod cone dystrophy. Clinical characterisation and imaging of the patients highlighted distinctive features which will direct future identification and molecular screening of patients. Residual retinal integrity and function in young patients and patients with milder phenotype suggests that AIPL1 defects may be amenable to treatment

Tracking Control of Vertical Pneumatic Artificial Muscle System Using PID

The advantages of pneumatic system such as compactness, high power to weight ratio, ease of maintenance, cleanliness and inherent safety led to the development of McKibben muscle and pneumatic artificial muscle (PAM). However, the air compressibility and the lack of damping ability of PAM bring dynamic delay to the pressure response and causes oscillatory motion to occur. It is not easy to realize the motion with high accuracy and high speed due to all the non-linear characteristics of pneumatic system. In this paper, we present a vertical PAM system with a simple PID controller to control the motion of the PAM. The experiment setup is explained and Ziegler Nichols tuning method is used in getting the approximation PID parameters. The effectiveness of the proposed control algorithm is demonstrated through experiments

Effects of perceived social isolation, fear of social isolation and gratitude during COVID-19 pandemic on anxiety in Malaysia

YesMany governments including Malaysia imposed movement restrictions as public health measure to minimize COVID-19 (coronavirus) risks. Due to prolonged isolation, poorer physical and mental health is expected in the general population. Our aims were to examine (1) the mediating role of perceived social isolation (SI) and fear of social isolation (FSI) on the relationship between gratitude and anxiety, and (2) to explore the moderating role of age, education and socioeconomic status (SES) on the mediation model. A total of 427 participants currently living in Malaysia (Mage = 37.90, SD = 16.51, 313 females) completed a survey on isolation, gratitude and anxiety during a period of national lockdown. Results showed that that those with higher gratitude reported having less SI and FSI and less anxiety (Model 1). In Model 2 with age as moderator, young adults (YA) and middle-aged adults (MA) who had higher gratitude experienced lower SI and in turn had lowered anxiety, but such mediating role of SI was not observed among older adults (OA). As for FSI, MA who had higher gratitude had lower FSI and also lower anxiety but this relationship was not observed in YA or OA. We also examined the role of education and SES as moderators in the parallel mediation analysis. Results showed that the indirect association of gratitude with anxiety via FI and FSI was moderated by both education and SES. Specifically, among those with low education levels (regardless of SES), those with higher gratitude had lower SI and FSI which in turn reduced anxiety. This relationship is similar for those with medium level of education and from low and middle level of SES as well. Our findings highlight the importance of having some coping mechanism e.g., gratitude and social connection during the pandemic to have higher wellbeing and quality of life, especially for MA sample and people from low education and SES background.This work was supported by Newton Fund Institutional Links grant ID: 331745333, under Newton-Ungku Omar Fund partnership to MHY. The grant is funded by the UK Department for Business, Energy and Industrial Strategy and Malaysian Industry-Government Group for High Technology (MIGHT) and delivered by the British Council. For further information, please visit www.newtonfund.ac.uk . The Newton Fund played no role in the planning and conceptualization of the manuscript, did not participate in the writing of the manuscript, and played no role in the decision to submit the manuscript

Health-related quality of life in pediatric patients with leukemia in Singapore: a cross-sectional pilot study

There has been a paradigm shift in health service delivery to a more holistic approach, which considers Quality of Life (QoL) and overall functioning. Health-Related Quality of Life (HRQoL) is a multidimensional construct that encompasses physical functioning as well as psychosocial aspects of emotional and social functioning. This study explored factors related to HRQoL in Asian pediatric patients with leukemia in Singapore. The available variables included: age, treatment duration, household income, gender, ethnicity, religion, diagnosis, and phase of treatment. It is hypothesized that the relationships will be significant. In the current study, there were 60 patients (60% males) with leukemia; their ages ranged from 1 to 21 years (Mean = 8.03, Standard Deviation = 4.55). The hypothesis was partially supported. Age had a significant positive relationship with physical functioning, r(60) = 0.28, p < 0.05, physical health, r(60) = 0.28, p < 0.05, and the total HRQoL score, r(60) = 0.29, p < 0.05. Treatment duration had a positive relationship with school functioning, r(60) = 0.28, p < 0.05. All other correlations were statistically non-significant. The effects of the available psychosocial variables of gender, ethnicity, and religion were examined on scores from the Pediatric Quality of Life Inventory (PedsQL). Ethnicity had a significant effect on social functioning, U = 292.00, p < 0.05, r = 0.3 (medium effect size). Specifically, Chinese (Median = 85.00, n = 33) had significantly higher scores on social functioning than others (Median = 70.00, n = 27). The remaining comparisons were statistically non-significant. The current findings added to QoL research, and provided an impetus for more research in the area of HRQoL for children with leukemia in Singapore

Electronic and thermal sequential transport in metallic and superconducting two-junction arrays

The description of transport phenomena in devices consisting of arrays of tunnel junctions, and the experimental confirmation of these predictions is one of the great successes of mesoscopic physics. The aim of this paper is to give a self-consistent review of sequential transport processes in such devices, based on the so-called "orthodox" model. We calculate numerically the current-voltage (I-V) curves, the conductance versus bias voltage (G-V) curves, and the associated thermal transport in symmetric and asymmetric two-junction arrays such as Coulomb-blockade thermometers (CBTs), superconducting-insulator-normal-insulator-superconducting (SINIS) structures, and superconducting single-electron transistors (SETs). We investigate the behavior of these systems at the singularity-matching bias points, the dependence of microrefrigeration effects on the charging energy of the island, and the effect of a finite superconducting gap on Coulomb-blockade thermometry.Comment: 23 pages, 12 figures; Berlin (ISBN: 978-3-642-12069-5

POVIJEST ZLARINA 3

Singapore Medical Journal354420-42

Analysis of acoustic emission during the melting of embedded indium particles in an aluminum matrix: a study of plastic strain accommodation during phase transformation

Acoustic emission is used here to study melting and solidification of embedded indium particles in the size range of 0.2 to 3 um in diameter and to show that dislocation generation occurs in the aluminum matrix to accommodate a 2.5% volume change. The volume averaged acoustic energy produced by indium particle melting is similar to that reported for bainite formation upon continuous cooling. A mechanism of prismatic loop generation is proposed to accommodate the volume change and an upper limit to the geometrically necessary increase in dislocation density is calculated as 4.1 x 10^9 cm^-2 for the Al-17In alloy. Thermomechanical processing is also used to change the size and distribution of the indium particles within the aluminum matrix. Dislocation generation with accompanied acoustic emission occurs when the melting indium particles are associated with grain boundaries or upon solidification where the solid-liquid interfaces act as free surfaces to facilitate dislocation generation. Acoustic emission is not observed for indium particles that require super heating and exhibit elevated melting temperatures. The acoustic emission work corroborates previously proposed relaxation mechanisms from prior internal friction studies and that the superheat observed for melting of these micron-sized particles is a result of matrix constraint.Comment: Presented at "Atomistic Effects in Migrating Interphase Interfaces - Recent Progress and Future Study" TMS 201

A Single Common Assay for Robust and Rapid Fragile X Mental Retardation Syndrome Screening From Dried Blood Spots

Background:FMR1 CGG trinucleotide repeat hyper-expansions are observed in 99% of individuals with fragile X mental retardation syndrome (FXS). We evaluated the reliability of a rapid single-step gender-neutral molecular screen for FXS when performed on DNA isolated from dried blood spots.Methods: DNA was extracted from dried blood spots of 151 individuals with intellectual disability or autism spectrum disorder, whose FMR1 repeat genotypes are known. Dried blood spots were blinded prior to DNA extraction and analysis by triplet primed PCR (TP-PCR) and melt curve analysis (MCA). All expansion-positive and representative expansion-negative samples were also genotyped by fluorescent TP-PCR and capillary electrophoresis (CE) to confirm repeat expansion status.Results: Three males and 12 females were classified as expanded by TP-PCR MCA, and were subsequently sized by fluorescent TP-PCR CE. Two males and four females carried premutations, while one male and eight females carried full mutations. All 19 non-expanded samples that were sized were confirmed as carrying only normal alleles. Replicate analysis of representative expansion-positive samples yielded reproducible melt peak profiles. TP-PCR MCA classifications were completely concordant with FMR1 CGG repeat genotypes.Conclusion: TP-PCR MCA of dried blood spot DNA accurately and reliably identifies presence/absence of FMR1 CGG repeat expansions in both genders simultaneously. This strategy may be suitable for rapid high-throughput first-tier screening for fragile X syndrome

BSS Plus compared to the vitreous of non-diabetics and diabetics

Letter to the EditorAbstract not availableJan Kokavec, Saban Horo, Weng Onn Chan, San H Min, Mei H Tan, John Grigg, Jagjit S Gilhotra, Henry S Newland, Shane R Durkin and Robert J Casso