Gene and Cell Therapy for AIPL1-Associated Leber Congenital Amaurosis: Challenges and Prospects

Leber congenital amaurosis (LCA) caused by AIPL1 mutations is one of the most severe forms of inherited retinal degeneration (IRD). The rapid and extensive photoreceptor degeneration challenges the development of potential treatments. Nevertheless, preclinical studies show that both gene augmentation and photoreceptor transplantation can regenerate and restore retinal function in animal models of AIPL1-associated LCA. However, questions regarding long-term benefit and safety still remain as these therapies advance towards clinical application. Ground-breaking advances in stem cell technology and genome editing are examples of alternative therapeutic approaches and address some of the limitations associated with previous methods. The continuous development of these cutting-edge biotechnologies paves the way towards a bright future not only for AIPL1-associated LCA patients but also other forms of IRD

Enhancing Axial Flow Fan Performance in Air-Cooled Condensers: Tip Vortex Manipulators and Comparative Analysis of Numerical Simulation and Experimental Testing

Direct dry-cooled power plants typically operate numerous large-diameter axial flow fans in air-cooled condensers to facilitate the condensation of steam in the plant thermodynamic cycle. Enhanced fan efficiency may, at scale, lead to significant parasitic power reductions and subsequent increases in plant power output. The performance of these fans may be increased by adding blade tip modifications which act to control blade tip leakage flow. Previous studies have shown that manipulating the tip leakage vortex increases the blade-to-air momentum transfer and stabilizes the air flow structures as it traverses the fan blade. This paper takes a step towards the development of improved tip vortex manipulators for an ACC fan. Three-dimensional computational fluid dynamic simulations, and experimental testing of the modified and unmodified fan within an ISO test facility is performed. The results are then utilized to assess the accuracy of the simulation model, visualize the manipulated flow structures at the blade tip, and ultimately quantify the effect of the endplate designs on fan performance. Excellent correlation between numerical and test results for the unmodified fan is observed, and the benefit of blade tip modification on fan performance is again confirmed experimentally. The simulation model however fails to predict improvements in fan performance under modification, and simulated tip leakage flows are investigated for clarification. It is hypothesized that deflection of tip endplates under operation account for differences between simulation and experiment, and that fluid-structure interaction analyses could potentially resolve discrepancies

Localised bridge loading for south africa using wim data

Bridges in South Africa are designed in accordance with TMH7, which was first published in 1981 and revised in 1989. Since the publication of the code, there have been revisions to traffic legislation and the nature of the vehicles that currently occupy our roads has changed over the past forty years with respect to gross vehicle weight, axle weight, number of axles, axle spacing and dynamic amplification. There is enough reason to believe that bridge loading may not be the same across our provinces as it is highly dependent on localised economic activity. This study investigates bridge loading across South Africa using weigh-in-motion data from six provinces. The number of vehicle records captured by WIM stations are approaching one hundred million and in-house software, together with extreme value statistics are used to compare load effects from the available data. The aim is to identify province specific bridge loading to prevent unnecessary conservatism in some locations.Papers presented at the 40th International Southern African Transport Conference on 04 -08 July 202

Expression and localization of NUB1 in Tauopathy and Alzheimer’s disease models

Alzheimer’s disease (AD) is characterized at a subcellular level by intracellular neurofibrillary tangles (NFTs), aggregates of hyperphosphorylated Tau, and by senile plaques, extracellular aggregates of amyloid beta peptides. Previous data revealed that Nedd8 ultimate buster 1 (NUB1) plays a role in reducing the aggregation and phosphorylation of Tau in an in vitro model. To clarify the role of NUB1 in AD, the spatiotemporal expression and localization of NUB1 was analyzed in T301L, a mouse model for Tauopathy characterized by NFTs, and in TASTPM mice, characterized by early development of senile plaques. The analysis revealed no change in the level of NUB1 expression in T301L mice and a significant decrease at 12 months in TASTPM mice. In brain cryosections, NUB1 expression was detected in the hippocampus and entorhinal cortex. Subcellularly, NUB1 was localized predominantly in the neuronal nuclei, but also in neuronal processes. In both mouse models at 12 months, NUB1 signal was observed to co-localize with AT8 positive cytoplasmic aggregates. Moreover in TASTPM mice, a NUB1 cytoplasmic signal was observed in non-neuronal cells. Our data confirm that NUB1 could be a therapeutic target in AD and also help to establish the appropriate window of opportunity for therapeutic intervention

Identifying abnormal vehicle subclasses from wim data for the structural design of highway bridges in South Africa

Papers presented virtually at the 41st International Southern African Transport Conference on 10-13 July 2023.Abnormal vehicle loads pose significant detrimental effects when crossing bridges. By characterising the traffic load effects experienced on bridges caused by abnormal vehicles, allows for more reliable bridge design practices. This paper presents an innovative approach to identify and characterise subclasses of abnormal vehicle types from weigh-in-motion (WIM) data, by employing Gaussian Mixture Modelling to the load effects. Each subclass of abnormal vehicles has unique statistical properties and Gaussian distributions are utilised to determine characteristic load effects and reliability-based partial factors for each subclass. The aim of this paper is to characterise abnormal vehicles, and how this information can aid codified bridge design practises in the industry

The role of NUB1 in the clearance of tau aggregates in Alzheimer's disease

BACKGROUND: Intraneuronal aggregations of abnormal hyperphosphorylated tau are a hallmark of Alzheimer’s disease. Previous data revealed that NEDD8 ultimate buster 1 (NUB1) reduces the aggregation and phosphorylation of tau in an in vitro model. NUB1 is a ubiquitin-like (UBL)/ ubiquitin-associated (UBA) protein that targets the down regulation of ubiquitin-like modifiers (NEDD8, FAT10), and aggregation-prone proteins leading to neurodegenerative disease (synphilin-1, huntingtin). The aim of the study is to understand how NUB1 affects tau aggregation and phosphorylation. METHODS: A GFP-tau inducible neuroblastoma cell line was generated and treated with proteasome inhibitor to induce the formation of aggresomes. GFP-tau cells were transduced with NUB1 lentiviral vectors both in the absence and presence of proteasome inhibitor, followed by western blotting, filter trap assays, immunoprecipitation and immunofluorescence. RESULTS: Inhibition of the proteasome induced the formation of GFP-tau aggresomes that were positive for phospho-tau (p-tau) markers (AT8, pS396). Filter trap assays revealed that NUB1 significantly decreased the ratio of p-tau to tau in the total cellular fraction (both soluble and insoluble), as well as in only the detergent insoluble fraction, both with and without proteasome inhibition. However, the ratio of tau and p-tau in the insoluble fraction to that in the total fraction revealed that the NUB1-mediated decrease in the levels of detergent insoluble tau and p-tau exceeded that of the overall decline in total levels, suggesting NUB1 can target aggregation-prone tau and p-tau. This effect of NUB1 was more pronounced for p-tau following proteasome inhibition. Blocking the proteasome induced the upregulation of p62 and increased the ratio of LC3B-II to LC3B-I. NUB1 induced further upregulation of autophagy following proteasome inhibition as seen by an increase in the LC3B-II/LC3B-I ratio and changes in LC3B positive puncta in cells. Finally, GFP-tau aggresomes were positive for p62 and NUB1 overexpression promoted the interaction between GFP-tau and p62. CONCLUSIONS: These data suggest that NUB1 may play a role in the clearance of aggregation-prone tau and p-tau following inhibition of the proteasome via autophagy

A prospective study of paediatric preoperative fasting times at Red Cross War Memorial Children’s Hospital, Cape Town, South Africa

Background. Fasting for liquids and solids is recommended prior to procedures requiring anaesthesia, to reduce the risk of pulmonary aspiration. Children often experience excessive fasting, which is associated with negative physiological and behavioural consequences, and patient discomfort. The duration of preoperative fasting in children in South Africa (SA) is unknown.Objectives. To determine compliance with fasting guidelines and fasting times of children prior to elective procedures performed under anaesthesia at a paediatric hospital in Cape Town, SA. The primary focus was fasting for clear liquid. We also intended to identify the most common reasons for prolonged clear liquid fasting.Methods. Over a 7-week period, we prospectively captured fasting times of consecutive patients undergoing elective surgical, medical and radiological procedures at Red Cross War Memorial Children’s Hospital. Measurement outcomes were defined as the period from the last clear liquid, milk or solid feed to the start of anaesthesia. For analysis of compliance with preoperative fasting guidelines, institutional preoperative fasting target limits were established based on the standard 6-4-2-hour guideline.Results. The study included 721 elective paediatric cases. The mean (standard deviation (SD)) fasting time for clear liquids (n=585) was 8.0 (4.8) hours, with an adherence rate of 25.5% (95% confidence interval 22 - 29) to the institutional target of 2 - 4 hours. The mean (SD) fasting times for breastmilk (n=92), formula milk (n=116) and solid feeds (n=560) were 7.1 (2.8), 8.8 (2.8) and 13.9 (3.6) hours, respectively. The factors associated with clear liquid fasting >4 hours were inadequate fasting instructions, poor adherence to fasting orders, procedural delays and fasting to promote theatre flexibility.Conclusions. This study demonstrates that children in an SA hospital experience excessive fasting times prior to elective procedures. To reduce fasting durations and improve the quality of perioperative care, quality improvement interventions are required to create an adaptable fasting system that allows individualised fasting. Improving preoperative fasting times in children is the responsibility of all healthcare professionals in the multidisciplinary management team

The inherited blindness protein AIPL1 regulates the ubiquitin-like FAT10 pathway

Mutations in AIPL1 cause the inherited blindness Leber congenital amaurosis (LCA). AIPL1 has previously been shown to interact with NUB1, which facilitates the proteasomal degradation of proteins modified with the ubiquitin-like protein FAT10. Here we report that AIPL1 binds non-covalently to free FAT10 and FAT10ylated proteins and can form a ternary complex with FAT10 and NUB1. In addition, AIPL1 antagonised the NUB1-mediated degradation of the model FAT10 conjugate, FAT10-DHFR, and pathogenic mutations of AIPL1 were defective in inhibiting this degradation. While all AIPL1 mutants tested still bound FAT10-DHFR, there was a close correlation between the ability of the mutants to interact with NUB1 and their ability to prevent NUB1-mediated degradation. Interestingly, AIPL1 also co-immunoprecipitated the E1 activating enzyme for FAT10, UBA6, suggesting AIPL1 may have a role in directly regulating the FAT10 conjugation machinery. These studies are the first to implicate FAT10 in retinal cell biology and LCA pathogenesis, and reveal a new role of AIPL1 in regulating the FAT10 pathway