Calcium Dependent Regulatory Mechanism in Wolfram Syndrome: A Dissertation

Wolfram syndrome is a genetic disorder characterized by diabetes and neurodegeneration. Two causative genes have been identified so far, WFS1 and WFS2, both encoding endoplasmic reticulum (ER) localized transmembrane proteins. Since WFS1 is involved in the ER stress pathway, Wolfram syndrome is considered an ER disease. Despite the underlying importance of ER dysfunction in Wolfram syndrome, the molecular mechanism linking ER to the death of β cells and neurons has not been elucidated. The endoplasmic reticulum (ER) is an organelle that forms a network of enclosed sacs and tubes that connect the nuclear membrane and other organelles including Golgi and mitochondria. ER plays critical functions in protein folding, protein transport, lipid metabolism, and calcium regulation. Dysregulation of ER function disrupts normal cell metabolism and activates an array of anti-survival pathways, eventually leading to disease state. Here we show that calpain is involved in both prototypes of Wolfram syndrome. Calpain 2 activity is negatively regulated by WFS2 protein, and hyper-activation of calpain 2 by WFS2-knockdown leads to cell death. Calpain hyper-activation is also present in WFS1 loss of function cells due to the high cytosolic calcium. Extensive calpain activation exists in the Wolfram syndrome mouse model as well as in patient cells. A compound screen targeting ER homeostasis reveals that dantrolene, a ryanodine receptor inhibitor, can prevent cell death in cell models of Wolfram syndrome. Our results demonstrate that the pathway leading to calpain activation provides potential therapeutic targets for Wolfram syndrome and other ER diseases

Planning Reliability Assurance Tests for Autonomous Vehicles

Artificial intelligence (AI) technology has become increasingly prevalent and transforms our everyday life. One important application of AI technology is the development of autonomous vehicles (AV). However, the reliability of an AV needs to be carefully demonstrated via an assurance test so that the product can be used with confidence in the field. To plan for an assurance test, one needs to determine how many AVs need to be tested for how many miles and the standard for passing the test. Existing research has made great efforts in developing reliability demonstration tests in the other fields of applications for product development and assessment. However, statistical methods have not been utilized in AV test planning. This paper aims to fill in this gap by developing statistical methods for planning AV reliability assurance tests based on recurrent events data. We explore the relationship between multiple criteria of interest in the context of planning AV reliability assurance tests. Specifically, we develop two test planning strategies based on homogeneous and non-homogeneous Poisson processes while balancing multiple objectives with the Pareto front approach. We also offer recommendations for practical use. The disengagement events data from the California Department of Motor Vehicles AV testing program is used to illustrate the proposed assurance test planning methods.Comment: 29 pages, 5 figure

A calcium-dependent protease as a potential therapeutic target for Wolfram syndrome

Wolfram syndrome is a genetic disorder characterized by diabetes and neurodegeneration and considered as an endoplasmic reticulum (ER) disease. Despite the underlying importance of ER dysfunction in Wolfram syndrome and the identification of two causative genes, Wolfram syndrome 1 (WFS1) and Wolfram syndrome 2 (WFS2), a molecular mechanism linking the ER to death of neurons and β cells has not been elucidated. Here we implicate calpain 2 in the mechanism of cell death in Wolfram syndrome. Calpain 2 is negatively regulated by WFS2, and elevated activation of calpain 2 by WFS2-knockdown correlates with cell death. Calpain activation is also induced by high cytosolic calcium mediated by the loss of function of WFS1. Calpain hyperactivation is observed in the WFS1 knockout mouse as well as in neural progenitor cells derived from induced pluripotent stem (iPS) cells of Wolfram syndrome patients. A small-scale small-molecule screen targeting ER calcium homeostasis reveals that dantrolene can prevent cell death in neural progenitor cells derived from Wolfram syndrome iPS cells. Our results demonstrate that calpain and the pathway leading its activation provides potential therapeutic targets for Wolfram syndrome and other ER diseases

Distribution characteristics and formation mechanism of fluoride in typical mine water in Shendong Mining Area

Shendong mining area is located in the north of Shaanxi Province and the south of Ordos City, Inner Mongolia, with dry climate, sparse precipitation and water resources scarcity. A large amount of mine water produced in the process of coal mining is an important source of production and living water. However, the concentrations of fluoride in mine water in different regions of Shendong mining areas present significant differences, while the concentration is relatively high in some areas. Therefore, the distribution characteristics and genesis of high fluoride mine water was analyzed in this study, which was of great significance for the resource reuse of mine water. Based on the analysis results of 58 groups of mine water quality at different regions in the Shendong mining area, research methods such as mathematical statistics, piper three-line diagram, gibbs diagram, SI simulation, etc. were used. Meanwhile, XRF analysis was conducted on rock cores and coal seam roof rocks collected from different areas to explore the spatiotemporal distribution characteristics and formation mechanism of fluorine in mine water at different burial depths in the northeastern and central mining areas. The results showed that the concentration of F- in mine water varied from 0.3 to 13.7 mg/L, with an average value of 4.3 mg/L. The pH value of mine water with higher F- concentration was alkaline. In the horizontal direction, the F- concentration in mine water was higher in the north and southwest of Shendong mining area, while it presented lower in the southeast. The fluorine concentration presented an increasing tendency with the enhancement of mining depth in the vertical direction. The F- concentration of mine water replenished by groundwater in different depths of Yan'an Formation aquifer varied greatly. The lower F- concentration was observed in the Yan'an Formation aquifer with a depth of 80-130 meters , whereas the relatively higher value was shown at the 200-500 meters depth. The trend of fluorine concentration in mine water is not obvious with the changes in the season The XRF analysis of fluorinated minerals in rock samples from the Yan'an Group indicated that the contents of fluorinated minerals in the northern and western central mining areas were relatively higher compared with that in the eastern central mining area. The high F- concentration in mine water had a certain relationship with the hydro-chemical environment. Evaporation and concentration process, cation alternately adsorption, and mineral dissolution caused by water-rock interaction led to the enrichment of F- in groundwater

A soluble endoplasmic reticulum factor as regenerative therapy for Wolfram syndrome

Endoplasmic reticulum (ER) stress-mediated cell death is an emerging target for human chronic disorders, including neurodegeneration and diabetes. However, there is currently no treatment for preventing ER stress-mediated cell death. Here, we show that mesencephalic astrocyte-derived neurotrophic factor (MANF), a neurotrophic factor secreted from ER stressed cells, prevents ER stress-mediated β cell death and enhances β cell proliferation in cell and mouse models of Wolfram syndrome, a prototype of ER disorders. Our results indicate that molecular pathways regulated by MANF are promising therapeutic targets for regenerative therapy of ER stress-related disorders, including diabetes, retinal degeneration, neurodegeneration, and Wolfram syndrome

Apoptosis Is the Essential Target of Selective Pressure against p53, whereas Loss of Additional p53 Functions Facilitates Carcinoma Progression

The high frequency of p53 mutation in human cancers indicates the important role of p53 in suppressing tumorigenesis. It is well established that the p53 regulates multiple, distinct, cellular functions such as cell cycle arrest and apoptosis. Despite intensive studies, little is known about which function is essential, or if multiple pathways are required, for p53-dependent tumor suppression in vivo. Using a mouse brain carcinoma model that shows high selective pressure for p53 inactivation, we found that even partially abolishing p53-dependent apoptosis by Bax inactivation was sufficient to significantly reduce the selective pressure for p53 loss. This finding is consistent with previous reports that apoptosis is the primary p53 function selected against during Eμ-myc induced mouse lymphoma progression. However, unlike observed in the Eμ-myc induced lymphoma model, attenuation of apoptosis is not sufficient to phenocopy the aggressive tumor progression associated with complete loss of p53 activity. We conclude apoptosis is the primary tumor suppressive p53 function and the ablation of additional p53 pleiotropic effects further exacerbates tumor progression

Intravenous Polymyxin B as Adjunctive Therapy to High-Dose Tigecycline for the Treatment of Nosocomial Pneumonia Due to Carbapenem-Resistant Acinetobacter baumannii and Klebsiella pneumoniae: A Propensity Score-Matched Cohort Study

Although the combination of polymyxin and tigecycline is widely used in treating carbapenem-resistant bacterial infections, the benefit of this combination is still uncertain. To assess whether adding polymyxin B to the high-dose tigecycline regimen would result in better clinical outcomes than the high-dose tigecycline therapy in patients with pneumonia caused by carbapenem-resistant Klebsiella pneumoniae and Acinetobacter baumannii, we conducted a propensity score-matched cohort study in a single center between July 2019 and December 2021. Of the 162 eligible patients, 102 were included in the 1:1 matched cohort. The overall 14-day mortality in the matched cohort was 24.5%. Compared with high-dose tigecycline, the combination therapy was not associated with better clinical outcomes, and showed similar 14-day mortality (OR, 0.72, 95% CI 0.27–1.83, p = 0.486), clinical cure (OR, 1.09, 95% CI 0.48–2.54, p = 0.823), microbiological cure (OR, 0.96, 95% CI 0.39–2.53, p = 0.928) and rate of nephrotoxicity (OR 0.85, 95% CI 0.36–1.99, p = 0.712). Subgroup analyses also did not demonstrate any statistical differences. Based on these results, it is reasonable to recommend against adding polymyxin B to the high-dose tigecycline regimen in treating pneumonia caused by carbapenem-resistant K. pneumoniae and A. baumannii

Power Allocation Strategy of Maximizing Secrecy Rate for Secure Directional Modulation Networks

In this paper, given the beamforming vector of confidential messages and artificial noise (AN) projection matrix and total power constraint, a power allocation (PA) strategy of maximizing secrecy rate (Max-SR) is proposed for secure directional modulation (DM) networks. By the method of Lagrange multiplier, the analytic expression of the proposed PA strategy is derived. To confirm the benefit from the Max-SRbased PA strategy, we take the null-space projection (NSP) beamforming scheme as an example and derive its closed-form expression of optimal PA strategy. From simulation results, we find the following facts: in the medium and high signal-to-noiseratio (SNR) regions, compared with three typical PA parameters such ? = 0:1, 0:5, and 0:9, the optimal PA shows a substantial SR performance gain with maximum gain percent up to more than 60%. Additionally, as the PA factor increases from 0 to 1, the achievable SR increases accordingly in the low SNR region whereas it first increases and then decreases in the medium and high SNR regions, where the SR can be approximately viewed as a convex function of the PA factor. Finally, as the number of antennas increases, the optimal PA factor becomes large and tends to one in the medium and high SNR region. In other words, the contribution of AN to SR can be trivial in such a situation

Generation of host-directed and virus-specific antivirals using targeted protein degradation promoted by small molecules and viral RNA mimics.

Targeted protein degradation (TPD), as exemplified by proteolysis-targeting chimera (PROTAC), is an emerging drug discovery platform. PROTAC molecules, which typically contain a target protein ligand linked to an E3 ligase ligand, recruit a target protein to the E3 ligase to induce its ubiquitination and degradation. Here, we applied PROTAC approaches to develop broad-spectrum antivirals targeting key host factors for many viruses and virus-specific antivirals targeting unique viral proteins. For host-directed antivirals, we identified a small-molecule degrader, FM-74-103, that elicits selective degradation of human GSPT1, a translation termination factor. FM-74-103-mediated GSPT1 degradation inhibits both RNA and DNA viruses. Among virus-specific antivirals, we developed viral RNA oligonucleotide-based bifunctional molecules (Destroyers). As a proof of principle, RNA mimics of viral promoter sequences were used as heterobifunctional molecules to recruit and target influenza viral polymerase for degradation. This work highlights the broad utility of TPD to rationally design and develop next-generation antivirals

A Prospective Study of Leukocyte Telomere Length and Risk of Type 2 Diabetes in Postmenopausal Women

Telomere length (TL) has been implicated in the pathogenesis of age-related disorders. However, there are no prospective studies directly investigating the role of TL and relevant genes in diabetes development. In the multiethnic Women’s Health Initiative, we identified 1,675 incident diabetes case participants in 6 years of follow-up and 2,382 control participants matched by age, ethnicity, clinical center, time of blood draw, and follow-up duration. Leukocyte TL at baseline was measured using quantitative PCR, and Mendelian randomization analysis was conducted to test whether TL is causally associated with diabetes risk. After adjustment for matching and known diabetes risk factors, odds ratios per 1-kilobase increment were 1.00 (95% CI 0.90–1.11) in whites, 0.95 (0.85–1.06) in blacks, 0.96 (0.79–1.17) in Hispanics, and 0.88 (0.70–1.10) in Asians. Of the 80 single nucleotide polymorphisms (SNPs) in nine genes involved in telomere regulation, 14 SNPs were predictive of TL, but none were significantly associated with diabetes risk. Using ethnicity-specific SNPs as randomization instruments, we observed no statistically significant association between TL and diabetes risk (P = 0.52). Although leukocyte TL was weakly associated with diabetes risk, this association was not independent of known risk factors. These prospective findings indicate limited clinical utility of TL in diabetes risk stratification among postmenopausal women