Particle-filter-based fault diagnosis for the startup process of an open-cycle liquid-propellant rocket engine

This study introduces a fault diagnosis algorithm based on particle filtering for open-cycle liquid-propellant rocket engines (LPREs). The algorithm serves as a model-based method for the startup process, accounting for more than 30% of engine failures. Similar to the previous fault detection and diagnosis (FDD) algorithm for the startup process, the algorithm in this study is composed of a nonlinear filter to generate residuals, a residual analysis, and a multiple-model (MM) approach to detect and diagnose faults from the residuals. In contrast to the previous study, this study makes use of the modified cumulative sum (CUSUM) algorithm, widely used in change-detection monitoring, and a particle filter (PF), which is theoretically the most accurate nonlinear filter. The algorithm is confirmed numerically using the CUSUM and MM methods. Subsequently, the FDD algorithm is compared with an algorithm from a previous study using a Monte Carlo simulation. Through a comparative analysis of algorithmic performance, this study demonstrates that the current PF-based FDD algorithm outperforms the algorithm based on other nonlinear filters.This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (No. RS-2022-00164702)

Leukotactin-1/CCL15-induced chemotaxis signaling through CCR1 in HOS cells

AbstractLeukotactin-1 (Lkn-1)/CCL15 is a recently cloned CC-chemokine that binds to the CCR1 and CCR3. Although Lkn-1 has been known to function as a chemoattractant for neutrophils, monocytes and lymphocytes, its cellular mechanism remains unclear. To understand the mechanism of Lkn-1-induced chemotaxis signaling, we examined the chemotactic activities of human osteogenic sarcoma cells expressing CCR1 in response to Lkn-1 using inhibitors of signaling molecules. Inhibitors of Gi/Go protein, phospholipase C (PLC) and protein kinase Cδ (PKCδ) inhibited the chemotactic activity of Lkn-1 indicating that Lkn-1-induced chemotaxis signal is transduced through Gi/Go protein, PLC and PKCδ. The activities of PLC and PKCδ were also enhanced by Lkn-1 stimulation. Chemotactic activity of Lkn-1 was inhibited by the treatment of cycloheximide and actinomycin D suggesting that newly synthesized proteins are needed for chemotaxis. Nuclear factor-κB (NF-κB) inhibitor reduced chemotactic activity of Lkn-1. DNA binding activity of NF-κB was also enhanced by Lkn-1 stimulation. These results suggest that Lkn-1 transduces the signal through Gi/Go protein, PLC, PKCδ, NF-κB and newly synthesized proteins for chemotaxis

Lamivudine plus adefovir combination therapy for lamivudine resistance in hepatitis-B-related hepatocellular carcinoma patients

Background/AimsLamivudine (LAM) plus adefovir (ADV) combination therapy has been accepted as one of the best treatments for LAM-resistant chronic hepatitis B (CHB). The aim of this study was to determine the efficacy of this combination therapy in hepatocellular carcinoma (HCC) patients.MethodsThe medical records of CHB patients who developed LAM resistance and were treated with LAM plus ADV combination therapy for more than 6 months were reviewed. Their virological response (VR; undetectable HBV DNA) and biochemical response (BR; alanine aminotransferase normalization) were evaluated, and the findings of HCC and non-HCC patients were compared.ResultsThe data from 104 patients (19 with HCC and 85 without HCC) were analyzed. The VR rates did not differ significantly between the HCC and non-HCC groups: 33.3% vs. 55.6% at 12 months (P=0.119), 58.3% vs. 67.2% at 24 months (P=0.742), 50% vs. 69.8% at 36 months (P=0.280), and 66.7% vs. 71.0% at 48 months (P=1.000). The BR rates also did not differ significantly between the groups: 55.6% vs. 84.0% at 12 months (P=0.021), 58.3% vs. 83.8% at 24 months (P=0.057), 70.0% vs. 77.8% at 36 months (P=0.687), and 66.7% vs. 80.6% at 48 months (P=0.591).ConclusionsThe efficacy of LAM plus ADV combination therapy is comparable in HCC and non-HCC patients

Hepatitis B surface antigen levels at 6 months after treatment can predict the efficacy of lamivudine-adefovir combination therapy in patients with lamivudine-resistant chronic hepatitis B

Background/AimsQuantitation of hepatitis B surface antigen (HBsAg) is an increasingly popular method to determine the treatment response in chronic hepatitis B (CHB) patients. The clinical value of HBsAg level measurement during rescue therapy for lamivudine (LMV)-resistant CHB patients have not been evaluated to date. Therefore, this study investigated the correlation between HBsAg level and treatment response in LMV-resistant CHB patients treated with adefovir (ADV) add-on therapy.MethodsLMV-resistant CHB patients treated with LMV-ADV combination therapy for over 2 years were included. HBsAg levels were measured at 6 month intervals until 1 year, and annually thereafter. Treatment response was assessed by determining the virological response (VR, undetectable HBV DNA levels) during treatment.ResultsFifty patients were included, of which 40 showed a VR. HBsAg levels were not different significantly at baseline (4.0 vs. 3.6 Log10 IU/mL, P=0.072). However, the HBsAg level decreased after 6 months of treatment in patients with a VR and became different significantly between the groups thereafter (3.9 vs. 3.3 at 6 months, P=0.002; 3.8 vs. 3.2 at 1 year, P=0.004; 3.9 vs. 3.2 at 2 years, P=0.008; 3.7 vs. 3.1 at 3 years, P =0.020).ConclusionsThe HBsAg level at 6 months after treatment can help predict treatment response

HBsAg level and clinical course in patients with chronic hepatitis B treated with nucleoside analogue: five years of follow-up data

Background/AimsQuantification of the hepatitis B surface antigen (HBsAg) is increasingly used to determine the treatment response in patients with chronic hepatitis B (CHB). However, there are limited data about the clinical implications of Quantification of HBsAg long-term nucleoside analogue treatment for CHB. We investigated the clinical correlation between HBsAg level and clinical course in patients with CHB who are treated long-term with nucleoside analogues.MethodsPatients with CHB who started lamivudine or entecavir monotherapy before June 2007 were enrolled. HBsAg was quantified at baseline, at 6 months, and at 1, 2, 3, 4, and 5 years of treatment. We compared data between the groups according to the presence or absence of a virological response (VR) and resistance.ResultsForty-eight patients were analyzed. There was no definite reduction in HBsAg level during the early period of treatment; differences in HBsAg levels between baseline and each time point were significant only at 5 years (P=0.028). In a subgroup analysis, this difference was significant only in non-resistant patients at 5 years (P=0.041).ConclusionsThere was no definite decrease in the HBsAg level during the early period of nucleoside analogue treatment, with long-term treatment being required to observe a significant reduction

The efficacy of tenofovir-based therapy in patients showing suboptimal response to entecavir-adefovir combination therapy

Background/Aims: Before tenofovir (TDF) become available in South Korea, combination therapy with entecavir (ETV) and adefovir (ADV) was the most potent regimen for chronic hepatitis B (CHB) patients who fail to respond to rescue therapy for drug resistance. We analyzed the efficacy of ETV-ADV combination therapy and investigated the clinical and clonal results of TDF-based rescue therapy in CHB patients refractory to this combination. Methods: We retrospectively reviewed the medical records of CHB patients treated for up to 3 years with ETV-ADV combination therapy as a rescue therapy for drug resistance. In cases refractory to this combination, clinical and clonal analyses were performed for TDF-based rescue therapy. Results: The analysis was performed on 48 patients. Twelve patients achieved a virological response (VR) within 3 years. A VR was subsequently achieved in nine of the ten patients without a VR who switched to TDF monotherapy. A VR was also achieved in six of the seven patients who switched to lamivudine-TDF combination therapy, and in two of the two patients who switched to ETV-TDF combination therapy. In an in vitro susceptibility test, viral replication was detected with TDF monotherapy but not with ETV-TDF combination therapy. Conclusions: The efficacy of ETV-ADV combination therapy was insufficient in CHB patients who were refractory to rescue therapy. A more potent regimen such as ETV-TDF combination therapy may be considered in such refractory cases

The refit model for end-stage liver disease-Na is not a better predictor of mortality than the refit model for end-stage liver disease in patients with cirrhosis and ascites

Background/AimsThe modification of the Model for End-Stage Liver Disease (MELD) scoring system (Refit MELD) and the modification of MELD-Na (Refit MELDNa), which optimized the MELD coefficients, were published in 2011. We aimed to validate the superiority of the Refit MELDNa over the Refit MELD for the prediction of 3-month mortality in Korean patients with cirrhosis and ascites.MethodsWe reviewed the medical records of patients admitted with hepatic cirrhosis and ascites to the Konkuk University Hospital between January 2006 and December 2011. The Refit MELD and Refit MELDNa were compared using the predictive value of the 3-month mortality, as assessed by the Child-Pugh score.ResultsIn total, 530 patients were enrolled, 87 of whom died within 3 months. Alcohol was the most common etiology of their cirrhosis (n=271, 51.1%), and the most common cause of death was variceal bleeding (n=20, 23%). The areas under the receiver operating curve (AUROCs) for the Child-Pugh, Refit MELD, and Refit MELDNa scores were 0.754, 0.791, and 0.764 respectively; the corresponding values when the analysis was performed only in patients with persistent ascites (n=115) were 0.725, 0.804, and 0.796, respectively. The significant difference found among the Child-Pugh, Refit MELD, and Refit MELDNa scores was between the Child-Pugh score and Refit MELD in patients with persistent ascites (P=0.039).ConclusionsRefit MELD and Refit MELDNa exhibited good predictability for 3-month mortality in patients with cirrhosis and ascites. However, Refit MELDNa was not found to be a better predictor than Refit MELD, despite the known relationship between hyponatremia and mortality in cirrhotic patients with ascites

Reversible splenial lesion on the corpus callosum in nonfulminant hepatitis A presenting as encephalopathy

Reversible focal lesions on the splenium of the corpus callosum (SCC) have been reported in patients with mild encephalitis/encephalopathy caused by various infectious agents, such as influenza, mumps, adenovirus, Varicella zoster, Escherichia coli, Legionella pneumophila, and Staphylococcus aureus. We report a case of a reversible SCC lesion causing reversible encephalopathy in nonfulminant hepatitis A. A 30-year-old healthy male with dysarthria and fever was admitted to our hospital. After admission his mental status became confused, and so we performed electroencephalography (EEG) and magnetic resonance imaging (MRI) of the brain, which revealed an intensified signal on diffusion-weighted imaging (DWI) at the SCC. His mental status improved 5 days after admission, and the SCC lesion had completely disappeared 15 days after admission