Enhancement of visible light response of TiO2 photocatalyst by 3D-deposited Ag nanowires and its charge separation mechanism.

In 3D-deposited AgNW/TiO2, which is prepared by spray-applying titanium dioxide suspension to deposited silver nanowire sheets, the synergistic effects of increased crossing points of AgNWs to enhance localized surface plasmon resonance excitation and longer-lived electrons in the conduction band of TiO2 generated by plasmon-induced charge transfer have successfully resulted in photocatalytic activity in the visible light range. We have developed photocatalytic sheets in which TiO2 particles are uniformly attached to 3D-deposited AgNWs. Regarding the prepared sheet, it was confirmed that TiO2 was indeed well adhered to the AgNWs, and electron transfer was efficient at the interface. This sheet solves the problem that the response wavelength range of the photocatalytic reaction using TiO2 is only in the ultraviolet region and exhibits sufficient photocatalytic effect in the visible light region. Transient absorption spectroscopy measurements in the diffuse reflectance configuration confirmed that the electrons of AgNWs actually move into the conduction band of TiO2 under visible light and that the interaction is independent of the excitation light intensity, thereby extending the lifetime of the electrons.

A novel intervention for wound bed preparation in severe extremity trauma: Highly concentrated carbon dioxide bathing.

Introduction: In severe extremity trauma involving large tissue defects, early closure (e.g., free-flap surgery) of the defects is an essential step for good functional reconstruction; however, in some cases, early closure may be difficult. Highly concentrated carbon dioxide bathing, used to improve blood flow in ischemic limbs and skin ulcers, can also be applied in wound bed preparation for severe limb trauma. Patients and Methods: The three cases in this study required an average of 13 weeks of highly concentrated carbonated bathing, which led to significantly better wound bed preparation, even in the exposed bone and tendon regions. Results: We successfully achieved good functional limb reconstruction in patients with deep burns and severe open fractures by reducing wound infection and facilitating good wound bed preparation. Conclusions: Highly concentrated carbon dioxide bathing was sufficient to prevent frequent wound infections, even in severe extremity trauma involving large soft-tissue defects such as deep crush burns and Gustilo Anderson classification ≥3b open fractures of the extremities. To our knowledge, such interventions have not been reported in the past and are valuable as new procedures for wound bed preparation in severe extremity trauma from both cost and wound infection control perspectives.

Successful laparoscopic retroperitoneal tumor resection using mixed reality and guiding marker techniques.

Introduction: Small tumors may be difficult to identify visually and require preoperative effort to locate. Recent advancements in mixed reality technology have improved surgical accuracy in various departments. Here, we present the application of mixed reality-assisted surgery and a guiding marker in the case of small retroperitoneal metastasis of uterine cancer. Case presentation: A 67-year-old female with a history of uterine cancer had a retroperitoneal metastasis in the lateroconal fascia near the right diaphragm, measuring 2 cm and infiltrating the peritoneum. We performed precise surgical planning using the preoperative mixed reality software "Holoeyes" on a head-mounted display called HoloLens2. Novel techniques, including ultrasonography-guided placement of a guiding marker and strategic port-site placement facilitated by HoloLens2, ensured accurate tumor identification and laparoscopic resection with minimal blood loss and no intraoperative complications. Conclusion: The use of mixed reality-assisted surgery and a guiding marker effectively enhanced the precision of retroperitoneal tumor resection.

Extensive ablation for persistent atrial fibrillation patients with mitral regurgitation: Insights from the EARNEST-PVI prospective randomized trial.

BACKGROUND: Extensive ablation in addition to pulmonary vein isolation (PVI) in patients with persistent atrial fibrillation (AF) has not yielded consistent results, indicating diversity in their efficacy. Mitral regurgitation (MR) associated with AF may indicate a higher prevalence of arrhythmogenic substrate, suggesting potential benefits of extensive ablation for these patients. METHODS: This post-hoc analysis of the EARNEST-PVI trial compared PVI alone versus an extensive ablation strategy (PVI-plus) in persistent AF patients, stratified by MR presence. The primary endpoint of the study was the recurrence of AF. The secondary endpoints included death, cerebral infarction, and procedure-related complications. RESULTS: The trial included 495 eligible patients divided into MR and non-MR groups. The MR group consisted of 192 patients (89 in the PVI-alone arm and 103 in the PVI-plus arm), while the non-MR group had 303 patients (158 in the PVI-alone arm and 145 in the PVI-plus arm). In the non-MR group, recurrence rates were similar between PVI-alone and PVI-plus arms (Log-rank P = 0.47, Hazard ratio = 0.85 [95%CI: 0.54-1.33], P = 0.472). However, in the MR group, PVI-plus was significantly more effective in preventing AF recurrence (Log-rank P = 0.0014, Hazard ratio = 0.40 [95%CI: 0.22-0.72], P = 0.0021). No significant differences were observed in secondary endpoints between the two arms. CONCLUSIONS: For persistent AF patients with mild or greater MR, receiving PVI-plus was superior to PVI-alone in preventing AF recurrence. Conversely, for patients without MR, the effectiveness of extensive ablation was not demonstrated. These findings suggest tailoring ablation strategies based on MR presence can lead to better outcomes in AF management.

Disinfection and monitoring of Mycobacterium avium complex in the environment: A novel approach to the management of hot tub lung.

A 45-year-old man visited our hospital with a chronic cough and breathing difficulties. Chest computed tomography revealed diffuse granular shadows. Mycobacterium avium (M. avium) was cultured from bronchoalveolar lavage fluid (BALF). Surgical lung biopsy revealed non-necrotizing granulomas, and M. avium-specific PCR was positive in the tissue. M. avium was also cultured in a sample from the inlet of the patient's bathtub. Mycobacterium avium tandem repeat variable-number tandem-repeat loci (MATR-VNTR) analysis confirmed that the M. avium cultured from BALF and the bathtub inlet had identical allele profiles. The patient's symptoms and oxygenation improved while the patient was in hospital, presumably because of lack of ongoing exposure to M. avium. He was diagnosed with hot tub lung. We advised the patient to avoid bathing to avoid re-exposure. However, the patient was unwilling to follow this advice. Therefore, his bathtub and pipework were disinfected by heating them to over 70 °C. We confirmed that the disinfection has been successful by repeated culture of environmental samples. Three months after resuming bathtub use, the patient's symptoms resolved, and the pulmonary shadows seen on the initial radiography did not recur. For the treatment of hot tub lung, disinfection of M. avium complex in the environment should be considered and the environment should be monitored to confirm eradication.

Impact of the coronavirus disease pandemic on robot-assisted radical prostatectomy and urologists' treatment behaviors: A single tertiary center retrospective study.

OBJECTIVES: To assess whether the coronavirus disease (COVID-19) pandemic affected the outcomes of robot-assisted radical prostatectomy (RARP) and urologists' treatment behaviors. METHODS: We retrospectively examined the medical records of 208 patients who had undergone RARP between August 2017 and December 2022. We compared the rate of preoperative androgen deprivation therapy (ADT), waiting period for RARP, patients' baseline characteristics and quality of life (QOL), proportion of adverse pathology on the RARP specimen, rate of Gleason grade group upgrading from biopsy to the RARP specimen, and prostate-specific antigen (PSA) recurrence-free survival between the pre-pandemic and pandemic groups. RESULTS: The rate of preoperative ADT was significantly higher during than before the COVID-19 pandemic (13.7% vs. 1.9%; p = 0.002). The baseline physical and mental QOL scores did not differ significantly between the groups. The proportion of D'Amico low-risk patients was significantly lower (13.6% vs. 1.2%, p = 0.005) and waiting period for RARP was significantly shorter (median 3.5 months vs. 4.0 months, p = 0.016) in the pandemic group than in the pre-pandemic group. There was no significant difference in the proportion of adverse pathology between the groups (p = 0.104); however, the upgrading rate was significantly higher in the pre-pandemic group (p = 0.002). There was no significant difference in PSA recurrence-free survival between the groups (log-rank, p = 0.752). CONCLUSIONS: The COVID-19 pandemic did not adversely affect the oncologic outcomes of RARP and QOL before RARP. However, it caused urologists to increase the use of preoperative ADT and to reserve RARP for higher-risk cases.

Usefulness of fluorescent ureteral catheter during laparoscopic residual ureterectomy.

Introduction: There have been reports of surgery for residual ureteral tumors, most of them involved open surgeries. Herein, we report a case of retroperitoneal scopic left ureteral resection and partial cystectomy, performed by placing a fluorescent ureteral catheter in the residual ureter. Case presentation: A 79-year-old man was admitted to our hospital with a chief complaint of gross hematuria. He had undergone transperitoneal left radical nephrectomy due to angiomyolipoma 20 years ago. Computed tomography and Magnetic resonance imaging revealed a solid tumor in the left residual ureter. Retroperitoneal scopic residual ureterectomy has been performed. During the operation, a fluorescent ureteral catheter proved to be very helpful in detecting the ureter. Conclusion: A fluorescent ureteral catheter is considered to be a useful tool in laparoscopic surgery, especially in cases where identification of the ureter is expected to be difficult, such as the residual ureter in this case.

En bloc resection of a large bilateral vulvar lipoma through a caesarean scar: A case report.

Large bilateral symmetrical vulvar tumors are rare. A 30-year-old multiparous Asian woman presented with severe discomfort during urination and intercourse owing to a large bilateral symmetrical lipoma in the labia majora. En bloc resection through a pre-existing Caesarean scar achieved good cosmetic and symptomatic results. This alternative and unique approach may be helpful in similar rare cases.

Peripheral neuropathy and nerve electrophysiological changes with enfortumab vedotin in patients with advanced urothelial carcinoma: a prospective multicenter cohort study.

BACKGROUND: Enfortumab vedotin is a novel antibody-drug conjugate used as a third-line therapy for the treatment of urothelial cancer. We aimed to elucidate the effect of enfortumab vedotin-related peripheral neuropathy on its efficacy and whether enfortumab vedotin-induced early electrophysiological changes could be associated with peripheral neuropathy onset. METHODS: Our prospective multicenter cohort study enrolled 34 patients with prior platinum-containing chemotherapy and programmed cell death protein 1/ligand 1 inhibitor-resistant advanced urothelial carcinoma and received enfortumab vedotin. The best overall response, progression-free survival, overall survival, and safety were assessed. Nerve conduction studies were also performed in 11 patients. RESULTS: The confirmed overall response rate and disease control rate were 52.9% and 73.5%, respectively. The median overall progression-free survival and overall survival were 6.9 and 13.5 months, respectively, during a median follow-up of 8.6 months. The patients with disease control had significantly longer treatment continuation and overall survival than did those with uncontrolled disease. Peripheral neuropathy occurred in 12.5% of the patients. The overall response and disease control rates were 83.3% and 100%, respectively: higher than those in patients without peripheral neuropathy (p = 0.028 and p = 0.029, respectively). Nerve conduction studies indicated that enfortumab vedotin reduced nerve conduction velocity more markedly in sensory nerves than in motor nerves and the lower limbs than in the upper limbs, with the sural nerve being the most affected in the patients who developed peripheral neuropathy (p = 0.011). CONCLUSION: Our results indicated the importance of focusing on enfortumab vedotin-induced neuropathy of the sural nerve to maximize efficacy and improve safety.

Uplift modeling to identify patients who require extensive catheter ablation procedures among patients with persistent atrial fibrillation.

Identifying patients who would benefit from extensive catheter ablation along with pulmonary vein isolation (PVI) among those with persistent atrial fibrillation (AF) has been a subject of controversy. The objective of this study was to apply uplift modeling, a machine learning method for analyzing individual causal effect, to identify such patients in the EARNEST-PVI trial, a randomized trial in patients with persistent AF. We developed 16 uplift models using different machine learning algorithms, and determined that the best performing model was adaptive boosting using Qini coefficients. The optimal uplift score threshold was 0.0124. Among patients with an uplift score ≥ 0.0124, those who underwent extensive catheter ablation (PVI-plus) showed a significantly lower recurrence rate of AF compared to those who received only PVI (PVI-alone) (HR 0.40; 95% CI 0.19-0.84; P-value = 0.015). In contrast, among patients with an uplift score < 0.0124, recurrence of AF did not significantly differ between PVI-plus and PVI-alone (HR 1.17; 95% CI 0.57-2.39; P-value = 0.661). By employing uplift modeling, we could effectively identify a subset of patients with persistent AF who would benefit from PVI-plus. This model could be valuable in stratifying patients with persistent AF who need extensive catheter ablation before the procedure.

Impact of frailty on cancer-related fatigue and quality of life in outpatients with prostate cancer: a cross-sectional study of patient-reported outcomes.

OBJECTIVE: To investigate the prevalence of frailty and its effects on cancer-related fatigue and quality of life among patients with prostate cancer. METHODS: In this cross-sectional study, questionnaires were administered to 254 outpatients who visited the Department of Urology at Kagawa University Hospital for prostate cancer; finally, 108 outpatients were analyzed. Frailty, cancer-related fatigue and quality of life were assessed using the G8 screening tool, Japanese version of the Brief Fatigue Inventory and Japanese version of the Short Form 8 Health Survey, respectively. We defined frailty based on a score ≤14 points and divided the patients into frailty and no-frailty groups. We also compared the severity of cancer-related fatigue and quality of life between groups. RESULTS: The prevalence of frailty among 108 outpatients was 63%. Older age correlated with frailty severity (P = 0.0007) but not cancer-related fatigue severity (P = 0.2391). The proportion of patients on treatment or with metastasis was not significantly different between groups. The frailty group had higher cancer-related fatigue severity (P = 0.004) and decreased levels of general activity, mood, walking ability, normal work and enjoyment of life, especially on the Brief Fatigue Inventory subscale. The frailty group had lower physical and mental quality of life than the no-frailty group or general population. CONCLUSIONS: The frailty rate for these patients increased with age, exceeding 60% regardless of the treatment status, and was associated with worsened cancer-related fatigue severity and reduced quality of life. Our study highlights the importance of assessing frailty when selecting treatment, especially in older patients.

U-Net Convolutional Neural Network for Real-Time Prediction of the Number of Cultured Corneal Endothelial Cells for Cellular Therapy.

Corneal endothelial decompensation is treated by the corneal transplantation of donor corneas, but donor shortages and other problems associated with corneal transplantation have prompted investigations into tissue engineering therapies. For clinical use, cells used in tissue engineering must undergo strict quality control to ensure their safety and efficacy. In addition, efficient cell manufacturing processes are needed to make cell therapy a sustainable standard procedure with an acceptable economic burden. In this study, we obtained 3098 phase contrast images of cultured human corneal endothelial cells (HCECs). We labeled the images using semi-supervised learning and then trained a model that predicted the cell centers with a precision of 95.1%, a recall of 92.3%, and an F-value of 93.4%. The cell density calculated by the model showed a very strong correlation with the ground truth (Pearson's correlation coefficient = 0.97, p value = 8.10 × 10-52). The total cell numbers calculated by our model based on phase contrast images were close to the numbers calculated using a hemocytometer through passages 1 to 4. Our findings confirm the feasibility of using artificial intelligence-assisted quality control assessments in the field of regenerative medicine.

Activation of cell adhesion and migration is an early event of platelet-rich plasma (PRP)-dependent stimulation of human adipose-derived stem/stromal cells.

Stem cell therapy is a promising treatment in regenerative medicine. Human adipose-derived stem/stromal cells (hASCs), a type of mesenchymal stem cell, are easy to harvest. In plastic and aesthetic surgery, hASC may be applied in the treatment of fat grafting, wound healing, and scar remodeling. Platelet-rich plasma (PRP) contains various growth factors, including platelet-derived growth factor (PDGF), which accelerates wound healing. We previously reported that PRP promotes the proliferation of hASC via multiple signaling pathways, and we evaluated the effect of PRP on the stimulation of hASC adhesion and migration, leading to the proliferation of these cells. When hASCs were treated with PRP, AKT, ERK1/2, paxillin and RhoA were rapidly activated. PRP treatment led to the formation of F-actin stress fibers. Strong signals for integrin ß1, paxillin and RhoA at the cell periphery of RPR-treated cells indicated focal adhesion. PRP promoted cell adhesion and movement of hASC, compared with the control group. Imatinib, an inhibitor of the PDGF receptor tyrosine kinase, inhibited the promotion of PRP-dependent cell migration. PDGF treatment of hASCs also stimulated cell adhesion and migration but to a lesser extent than PRP treatment. PRP promoted the adhesion and the migration of hASC, mediated by the activation of AKT in the integrin signaling pathway. PRP treatment was more effective than PDGF treatment in enhancing cell migration. Thus, the ability of PRPs to promote migration of hASC to enhance cell growth is evident.

Pathophysiological insights into machine learning-based subphenotypes of acute heart failure with preserved ejection fraction.

OBJECTIVE: The heterogeneous pathophysiology of the diverse heart failure with preserved ejection fraction (HFpEF) phenotypes needs to be examined. We aim to assess differences in the biomarkers among the phenotypes of HFpEF and investigate its multifactorial pathophysiology. METHODS: This study is a retrospective analysis of the PURSUIT-HFpEF Study (N=1231), an ongoing, prospective, multicentre observational study of acute decompensated HFpEF. In this registry, there is a predefined subcohort in which we perform multibiomarker tests (N=212). We applied the previously established machine learning-based clustering model to the subcohort with biomarker measurements to classify them into four phenotypes: phenotype 1 (n=69), phenotype 2 (n=49), phenotype 3 (n=41) and phenotype 4 (n=53). Biomarker characteristics in each phenotype were evaluated. RESULTS: Phenotype 1 presented the lowest value of N-terminal pro-brain natriuretic peptide (NT-proBNP), high-sensitive C reactive protein, tumour necrosis factor-α, growth differentiation factor (GDF)-15, troponin T and cystatin C, whereas phenotype 2, which is characterised by hypertension and cardiac hypertrophy, showed the highest value of these markers. Phenotype 3 showed the second highest value of GDF-15 and cystatin C. Phenotype 4 presented a low NT-proBNP value and a relatively high GDF-15. CONCLUSIONS: Distinctive characteristics of biomarkers in HFpEF phenotypes would indicate differential underlying mechanisms to be elucidated. The contribution of inflammation to the pathogenesis varied considerably among different HFpEF phenotypes. Systemic inflammation substantially contributes to the pathophysiology of the classic HFpEF phenotype with cardiac hypertrophy. TRIAL REGISTRATION NUMBER: UMIN-CTR ID: UMIN000021831.

The Prognostic Impact of In-Hospital Major Bleeding and Recurrence of Myocardial Infarction during Acute Phase after Percutaneous Coronary Intervention for Acute Myocardial Infarction.

AIM: Both recurrent myocardial infarction (ReMI) and bleeding events after acute myocardial infarction (AMI) were reportedly associated with increased mortality. To date, the prognostic impact of these events on subsequent outcomes in East Asians is still unclear. In this study, we aimed to investigate the impact of bleeding or thrombotic events during acute phase on subsequent mortality and time-dependent change of the impact in patients with AMI undergoing percutaneous coronary intervention (PCI). METHOD: We conducted a prospective, multicenter, observational study of patients with AMI (n=12,093). The patients who did not undergo emergent PCI were excluded. In addition, the patients registered before 2003 were excluded because the data of bleeding severity was not obtained. Eligible patients were divided into two groups based on the occurrence of major bleeding within 7 days of PCI, and the same approach was performed for ReMI within 7 days of PCI. The endpoint of this study was all-cause death. We assessed the impact of major bleeding and ReMI, which occurred within 7 days of index PCI, on the subsequent clinical outcomes up to 5 years. RESULTS: A total of 6,769 patients were found to be eligible. All-cause death occurred in 898 (13.3%) patients during a median follow-up period of 1,726 [511-1,840] days. After adjustment for multiple confounders, major bleeding in 7 days from index PCI was independently associated with higher 30-day and 30-day to 1-year mortality (odds ratio [OR]: 2.06 [1.45-2.92] p＜0.001, OR: 2.03 [1.28-3.15] p=0.002), whereas ReMI was not (OR: 1.93 [0.92-3.80] p=0.07, OR: 0.81 [0.24-2.03] p=0.68). Major bleeding and ReMI did not affect mortality between 1 and 5 years (hazard ratio [HR]: 1.32 [0.77-2.26] p=0.31, HR: 0.48 [0.12-1.94] p=0.30). CONCLUSION: Major bleeding in 7 days from admission was independently associated with higher 30-day and 1-year mortality but not during 1-5 years. ReMI did not affect mortality in all phases. We should be more concerned about bleeding event during acute phase after PCI.

Ultrastructural changes of vascular smooth muscle cells and resistance to vasospasm treatment in femoral arteries of an arteriosclerotic rat model.

The objective of this study was to establish an animal model of arteriosclerosis for assessing vasospasm and to investigate the relationship between arteriosclerosis and vasospasm. Twelve-week-old male Sprague-Dawley rats were fed a diet supplemented with adenine and vitamin D (adenine/vitD). Body weight, blood, and femoral artery histopathology were assessed at 2, 4, and 6 weeks. Change in the femoral artery was examined by transmission electron microscope (TEM). Vasospasm was induced by administering epinephrine extravascularly into the femoral artery and released by the treatment with lidocaine as a vasodilator. During this period, the extravascular diameter and blood flow were measured. The rats in the adenine/vitD group developed renal dysfunction, uremia, hyperphosphatemia, and elevated serum alkaline phosphatase. Histological and TEM analyses of the femoral arteries in the treated rats revealed the degeneration of elastic fibers and extensive calcification of the tunica media and intima. Vascular smooth muscles were degenerated and osteoblasts were developed, resulting in calcified arteriosclerosis. Vasospasm in arteriosclerotic arteries was detected; however, vasodilation as well as an increase in the blood flow was not observed. This study revealed the development of vasospasm in the femoral arteries of the arteriosclerotic rats and, a conventional vasodilator did not release the vasospasm.

Coronary arterial repair in patients with stable angina pectoris or acute coronary syndrome after ultrathin biodegradable polymer sirolimus-eluting stent implantation at 1-year follow-up by coronary angioscopy.

BACKGROUND: Imaging modality-based evidence is limited that compares the extent of coronary arterial repair after percutaneous coronary intervention between patients with stable angina pectoris (SAP) and those with acute coronary syndrome (ACS). METHODS: Between December 2018 and November 2021, a single-center, nonrandomized, observational study was conducted in 92 patients with SAP (n = 42) or ACS (n = 50), who were implanted with Orsiro sirolimus-eluting stent (O-SES) providing a hybrid (active and passive) coating and underwent 1-year follow-up by coronary angioscopy (CAS) after implantation. CAS assessed neointimal coverage (NIC), maximum yellow plaque (YP), and mural thrombus (MT). RESULTS: Baseline clinical characteristics were comparable between the SAP and ACS groups. The follow-up periods were comparable between the two groups (390.1 ± 69.9 vs. 390.6 ± 65.7 days, p = 0.99). The incidences of MT at 1 year after implantation were comparable between the two groups (11.4% vs. 11.1%, p = 0.92). The proportions of "Grade 1" in dominant NIC grades were highest in both groups, and the proportions of maximum YP grades and MT were comparable between the two groups. CONCLUSION: O-SES-induced coronary arterial repair at the site of stent implantation, irrespective of the types of coronary artery disease.

ß-blockers may be detrimental in frail patients with heart failure with preserved ejection fraction.

BACKGROUND: The effectiveness of ß-blocker in patients with heart failure with preserved ejection fraction (HFpEF) remains to be determined. We aimed to clarify the association between the use of ß-blocker and prognosis according to the status of frailty. METHODS: We compared prognosis between HFpEF patients with and without ß-blockers stratified with the Clinical Frailty Scale (CFS), using data from the PURSUIT-HFpEF registry (UMIN000021831). RESULTS: Among 1159 patients enrolled in the analysis (median age, 81.4 years; male, 44.7%), 580 patients were CFS ≤ 3, while 579 were CFS ≥ 4. Use of ß-blockers was associated with a worse composite endpoint of all-cause death and heart failure readmission in patients with CFS ≥ 4 (adjusted hazard ratio (HR) 1.43, 95% CI 1.10-1.85, p = 0.007), but was not significantly associated with this endpoint in those with CFS ≤ 3 (adjusted HR 0.95, 95% CI 0.71-1.26, p = 0.719) in multivariable Cox proportional hazard models. These results were confirmed in a propensity-matched analysis (HR in those with CFS ≥ 4: 1.42, 95% CI 1.05-1.90, p = 0.020; that in those with CFS ≤ 3: 0.83, 95% CI 0.60-1.14, p = 0.249), and in an analysis in which patients were divided into CFS ≤ 4 and CFS ≥ 5. CONCLUSIONS: Use of ß-blockers was significantly associated with worse prognosis specifically in patients with HFpEF and high CFS, but not in those with low CFS. Use of ß-blockers in HFpEF patients with frailty may need careful attention.

Direct numerical simulations of a microswimmer in a viscoelastic fluid.

This study presents the application of the smoothed profile (SP) method to perform direct numerical simulations for the motion of both passive and active "squirming" particles in Newtonian and viscoelastic fluids. We found that fluid elasticity has a significant impact on both the transient behavior and the steady-state velocity of the particles. Specifically, we observe that the swirling flow generated by the squirmer's surface velocity significantly enhances their swimming speed as the Weissenberg number increases, regardless of the swimming type. Furthermore, we find that pushers outperform pullers in Oldroyd-B fluids, suggesting that the speed of a squirmer depends on the swimmer type. To understand the physical origin of the phenomenon of swirling flow enhancing the swimming speed, we investigate the velocity field and polymer conformation around non-swirling and swirling neutral squirmers in viscoelastic fluids. Our investigation reveals that the velocity field around the neutral swirling squirmers exhibits pusher-like extensional flow characteristics, as well as an asymmetric polymer conformation distribution, which gives rise to this increased propulsion. This is confirmed by the investigation of the force on a fixed squirmer, which revealed that the polymer stress, particularly its diagonal components, plays a critical role in enhancing the swimming speed of swirling squirmers in viscoelastic fluids. Additionally, our results demonstrate that the maximum swimming speeds of swirling squirmers occur at an intermediate value of the fluid viscosity ratio for all swimmer types. These findings have important implications for understanding the behavior of particles and micro-organisms in complex fluids.