Intelligent optical performance monitor using multi-task learning based artificial neural network

An intelligent optical performance monitor using multi-task learning based artificial neural network (MTL-ANN) is designed for simultaneous OSNR monitoring and modulation format identification (MFI). Signals' amplitude histograms (AHs) after constant module algorithm are selected as the input features for MTL-ANN. The experimental results of 20-Gbaud NRZ-OOK, PAM4 and PAM8 signals demonstrate that MTL-ANN could achieve OSNR monitoring and MFI simultaneously with higher accuracy and stability compared with single-task learning based ANNs (STL-ANNs). The results show an MFI accuracy of 100% and OSNR monitoring root-mean-square error of 0.63 dB for the three modulation formats under consideration. Furthermore, the number of neuron needed for the single MTL-ANN is almost the half of STL-ANN, which enables reduced-complexity optical performance monitoring devices for real-time performance monitoring

Assessment of Cryoprotectant Concentration by Electrical Conductivity Measurement and Its Applications in Cryopreservation

This chapter presents an important application of the electrical conductivity measurement in cryopreservation. Long-term cryopreservation of cells and tissues is essential in both clinical treatments and fundamental researches. In order to reduce the cryo-injury to the cells during cryopreservation, cryoprotective agents (CPAs) should be added before freezing, but also removed after thawing duo to the cytotoxicity. In these steps, severe osmotic stresses may result in injuries to the cells too. Therefore, monitoring the addition and removal of CPAs to the cell samples is critical in order to prevent the osmotic injury. In this chapter, the electrical conductivity measurement was applied to assess the CPA concentration in cryopreservation. Firstly, the standard correlations between the CPA concentration and the electrical conductivity of the solutions (including CPA-NaCl-water ternary solutions and CPA-albumin-NaCl-water quaternary solutions) were experimentally obtained for a few mostly used CPAs. Then a novel ?dilution-filtration? system with hollow fiber dialyzer was designed and applied to remove the CPA from the solutions effectively. Measurement of electrical conductivity was validated as a safer and easier way to on-line and real-time monitoring of CPA concentration in cell suspensions. This work demonstrated a very important application of electrical conductivity in the biomedical engineering field

Progress in Cryopreservation of Stem Cells and Immune Cells for Cytotherapy

Cellular therapy with stem and immune cells has demonstrated significant success both in clinical treatments and the industrial market. Cryopreservation is a necessary and essential component of cellular therapy. In this chapter, first of all, some basic theories of cryoinjury and techniques in cryopreservation are reviewed. Then it focuses on the progress of cryopreservation of stem cells and immune cells, including new protocols and techniques, alternative cryoprotective agents (CPA), side effects after transplantation, and advances in reducing adverse reactions. Strategies to minimize adverse effects include medication before and after transplantation, optimizing the infusion procedure, reducing the CPA concentration or using alternative CPAs for cryopreservation, and removing CPA prior to infusion. Traditional and newly developed approaches including methods and devices for CPA removal are discussed. Future work is recommended including further optimization of cryopreservation protocols especially for lymphocytes; standardization of the optimized protocols with temperature monitoring and quality control; exploration of DMSO-free, serum-free, and even xeno-free media for cryopreservation; development of simple, reliable, and cost-effective devices for cryopreservation; and more fundamental cryobiological studies to avoid cellular injury.Keywords: cryopreservation, stem cell, immune cell, cytotherap

Cryobiology and Cryopreservation of Sperm

Low temperature has been utilized to keep living cells and tissues dormant but potentially alive for cryopreservation and biobanking with great impacts on scientific and biomedical applications. However, there is a critical contradiction between the purpose of the cryopreservation and experimental findings: the cryopreserved cells and tissues can be fatally damaged by the cryopreservation process itself. Contrary to popular belief, the challenge to the life of living cells and tissues during the cryopreservation is not their ability to endure storage at cryogenic temperatures (below −190°C); rather it is the lethality associated with mass and energy transport within an intermediate zone of low temperature (−15 to −130°C) that a cell must traverse twice, once during cooling and once during warming. This chapter will focus on (1) the mechanisms of cryoinjury and cryopretection of human sperm in cryopreservation, and (2) cryopreservation techniques and methods developed based on the understanding of the above mechanisms

Development of a Novel Electromagnetic Rewarming Technology for the Cryopreservation of Stem Cells with Large Volume

Applications of stem cells have been playing significant roles in scientific and clinical settings in the last few decades. The foundation of these approaches is successful cryopreservation of stem cells for future use. However, so far we can only cryopreserve stem cell suspension of small volumes in the order of 1 mL mostly due to the lack of an effective rewarming technique. Rapid and uniform rewarming has been approved to be beneficial, and sometimes, indispensable for the survival of cryopreserved stem cells, inhibiting ice recrystallization or devitrification. Unfortunately, the conventional water bath thawing method failed in providing the rapid and uniform rewarming. The conversion of electromagnetic (EM) energy into heat provides a possible solution to this problem. This chapter will focus on (1) analysis of the combined EM and heat transfer phenomenon in the rewarming of a biospecimen, (2) numerical investigation of the rewarming system, (3) practical setup of an EM resonance system, and (4) test of heating performance with large volume of cells

Design and baseline characteristics of the finerenone in reducing cardiovascular mortality and morbidity in diabetic kidney disease trial

Background: Among people with diabetes, those with kidney disease have exceptionally high rates of cardiovascular (CV) morbidity and mortality and progression of their underlying kidney disease. Finerenone is a novel, nonsteroidal, selective mineralocorticoid receptor antagonist that has shown to reduce albuminuria in type 2 diabetes (T2D) patients with chronic kidney disease (CKD) while revealing only a low risk of hyperkalemia. However, the effect of finerenone on CV and renal outcomes has not yet been investigated in long-term trials. Patients and Methods: The Finerenone in Reducing CV Mortality and Morbidity in Diabetic Kidney Disease (FIGARO-DKD) trial aims to assess the efficacy and safety of finerenone compared to placebo at reducing clinically important CV and renal outcomes in T2D patients with CKD. FIGARO-DKD is a randomized, double-blind, placebo-controlled, parallel-group, event-driven trial running in 47 countries with an expected duration of approximately 6 years. FIGARO-DKD randomized 7,437 patients with an estimated glomerular filtration rate >= 25 mL/min/1.73 m(2) and albuminuria (urinary albumin-to-creatinine ratio >= 30 to <= 5,000 mg/g). The study has at least 90% power to detect a 20% reduction in the risk of the primary outcome (overall two-sided significance level alpha = 0.05), the composite of time to first occurrence of CV death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for heart failure. Conclusions: FIGARO-DKD will determine whether an optimally treated cohort of T2D patients with CKD at high risk of CV and renal events will experience cardiorenal benefits with the addition of finerenone to their treatment regimen. Trial Registration: EudraCT number: 2015-000950-39; ClinicalTrials.gov identifier: NCT02545049

Development of Optimal Biopreservation Methods and Technology for Cellular Therapy and Clinical Diagnosis

Thesis (Ph.D.)--University of Washington, 2013Successful biopreservation of bio-samples, including DNA/RNA, proteins, bio-fluids, cells, tissues and organs, is vital for researches and clinical trials, enabling the diagnosis of disease, drug development and cellular therapy. Challenges in biopreservation (particularly cryopreservation) include selection of the optimal cryoprotective agent (CPA), successful addition of CPA, optimization of the cooling protocol, thawing of the frozen samples, removal of CPA after thawing, and others. In this dissertation, a few novel techniques are developed to determine the fundamental cryobiological properties of cells, optimize cryopreservation protocols and the applications of biopreservation in cellular therapy and disease diagnosis. The optimal cryopreservation protocol for a cell type is determined by the inherent cryobiological characteristics of the cells, including the cell membrane permeabilities to water and the CPA at different temperatures, the osmotically inactive cell volume fraction, the activation energy of water transport across cell membranes, the osmotically inactive cell volume fraction, osmotic tolerance limit, sensitivity to the CPA toxicity, intracellular ice formation (IIF) temperature, and others. To determine these cryobiological properties, two methods are proposed and applied: microfluidic perfusion channel and differential scanning calorimetry (DSC) measurements. For the microfluidic perfusion channel method, human vaginal mucosal immune cells (T cells and macrophages) were chosen because of their importance in HIV vaccine research and poor long-term preservation with current protocols. Using the micro-fabricated channel, cells can be trapped in the channel and observed under microscopy. Different solutions (2xPhosphate-buffered saline [PBS], 3xPBS, and CPA solutions) were fed into the channel. In response to the perfusion solutions, the cell volume changed (shrank or shrank then expanded). The volume excursion history of individual cells was recorded. After image analysis, the data were simulated to evaluate the cell membrane properties. The results showed that T cells and macrophages had relatively low membrane permeabilities, implying a low optimal cooling rate for these cells. Comparing four different CPAs (Dimethyl sulfoxide (DMSO), glycerol, propylene glycol and ethylene glycol), showed that glycerol crossed the cell membranes very slowly; therefore, it cannot be used for the cryopreservation of these cells. DMSO and propylene glycol could be good CPA options. Tests of CPA cytotoxicity demonstrated similar results. The results also showed that T cells were more susceptible to stresses than macrophages. While it is technically challenging to use the micro-perfusion channel method at temperatures below the freezing point, DSC can be used to evaluate the cell membrane properties at any sub-zero temperatures. Based on the fundamental theory developed by Devireddy et al., a "slow-fast-fast-slow" cooling program is used for cell suspensions. In the first slow cooling process, the measured heat release of ice crystallization includes the crystallization of extracellular water and the water that is transported from inside of the cells due to extracellular ice formation and consequently the osmolality gradient occurrence across the cell membranes. During the repeated fast cooling processes, cells are assumed to be killed and lysed. Some water will be bound to the proteins and cell debris of the lysed cells. Therefore, in the last slow cooling step, the heat release of ice crystallization will be lower than that of the first slow cooling step. The thermogram difference between the first and the last slow cooling steps can be analyzed to obtain the water transport history across cell membranes in the suspension during freezing; therefore, cell membrane properties at any temperature during cooling can be predicted. This approach was optimized and applied to measure the membrane properties of PBMC lymphocytes (including T cells and monocytes). The results were then applied in theoretical simulation to predict the optimal cooling rate for the cells. The prediction was consistent with the standard operating procedure (SOP) for PBMC cryopreservation. Another challenge in cryopreservation and cellular therapy is the addition and removal of CPA with minimal injury to the cells. In order to overcome this problem, a multi-functional cell processor based on semi-permeable hollow fibers and "dilution-filtration" working principle was developed. A novel approach of electrical conductivity measurement was also proposed for real-time, online monitoring of the residual CPA concentration in the cell suspension. The results showed that this system can be applied for successful cell concentration (control of the cell suspension volume) and removal of CPA with much lower cell loss. Furthermore, this automatic device with closed fluid loop can save labor significantly, reduce risk of contamination and decrease cell damage. Cryopreservation of bacteria and freeze-drying of proteins were also studied in this dissertation. Mycobacterium tuberculosis (MTB) was studied due to the challenges in tuberculosis diagnosis. Tuberculosis is the second leading infectious disease (only after HIV) causing death in the world. Fast and accurate diagnosis of MTB is still challenging. Cryopreservation of MTB cells is very important for pathological research, diagnosis and drug development. Due to the small size of MTB cells and the complex cell wall/membrane configuration, it is challenging to study their fundamental cryobiological properties. So, MTB cells were cryopreserved under systematically varied conditions and the effects on recovery were measured. The results showed that among all the parameters, slow cooling rate is the most important for successful MTB cryopreservation. Inconsistencies were found between the results of microbiological culturing and BacLight Live/Dead staining, implying that suboptimal cryopreservation might not cause severe damage to cell wall and/or membrane, but instead cause intracellular injury, which leads to the loss of cell viability. For long-term preservation of the MTB IgY antibodies, freeze-drying was applied. The results showed that the lyophilized IgY antibodies can be well preserved for up to 13 months at either room temperature or 4°C. Plans for further experiments are also presented in this dissertation, including cryopreservation and vitrification of mucosal immune cells and tissues based on fundamental researches and predicted protocol, multi-center evaluation of the developed techniques and protocols, and further optimization of the multi-functional cell processor

Non-Probabilistic Reliability Analysis of Slopes Based on Fuzzy Set Theory

Aimed at the problem of fuzzy uncertainty of geotechnical parameters in slope stability analysis, a non-probabilistic reliability analysis method for slopes based on fuzzy set theory is proposed. Geotechnical parameters are described as fuzzy numbers, which are transformed into interval numbers at different cut set levels by taking fuzzy sets. The corresponding non-probabilistic reliability indexes and failure degrees of the slope are calculated by the non-probabilistic reliability analysis method based on the ellipsoidal model, and then the overall failure degree of the slope is obtained by weighted average to judge the stability state of the slope. The feasibility of the method was verified by a case analysis. The results show that the type and shape parameters of the fuzzy affiliation function of geotechnical parameters have a great influence on the non-probabilistic reliability of the slope. The slope failure degrees obtained from trapezoidal fuzzy numbers were larger, the slope failure degrees obtained from triangular fuzzy numbers and normal fuzzy numbers were medium, and the slope failure degrees obtained from lognormal fuzzy numbers were smaller. When considering soil parameters as triangular fuzzy numbers, normal fuzzy numbers, or lognormal fuzzy numbers, with the reduction of the shape parameters, the non-probabilistic reliability indexes of the slope increased while the failure degrees decreased. Additionally, adopting the overall failure degree to evaluate the stability of the slope can effectively solve the problem where the calculation results are too conservative (if the non-probabilistic reliability index is greater than 1) to judge the stability state of the slope in the traditional non-probabilistic reliability method