Important Constituents of Heavy Water-containing Solution for Cold Storage and Subsequent Reperfusion on an Isolated Perfused Rat Liver

The University of Wisconsin (UW) solution is the most effective preservation solution currently used; however, to safely use expanded-criteria donor grafts, a new cold storage solution that alleviates graft injury more effectively is required. We prepared a heavy water (D2O)-containing buffer, Dsol, and observed strong protective effects during extended cold storage of rat hearts and livers. In the current study, we modified Dsol (mDsol) and tested its efficacy. The aim of the present study was to determine whether mDsol could protect the rat liver more effectively than the UW solution and to clarify the roles of D2O and deferoxamine (DFX). Rat livers were subjected to cold storage for 48 hours in test solutions: UW, mDsol, mDsol without D2O or DFX (mDsol-D2O[-], mDsol-DFX[-]), and subsequently reperfused on an isolated perfused rat liver for 90 minutes at 37°C. In the UW group, the liver was dehydrated during cold storage and rapidly expanded during reperfusion. Accordingly, the cumulative weight change was the highest in the UW group, together with augmented portal veinous resistance and ALT leakage and decreased oxygen consumption rate and bile production. These changes were significantly suppressed in the mDsol-treated group. In the mDsol-D2O(-) and mDsol-DFX(-) groups offered partial protection. In conclusion, mDsol appeared to be superior to the UW solution for simple cold storage of the rat liver, presumably due to improved microcirculation in the early phase of reperfusion. Both heavy water and deferoxamine are essential for alleviating seamless organ swelling that occurs during cold storage and subsequent reperfusion.

A Study of risk factors of postoperative ileus after laparoscopic colorectal resection

Aim

Postoperative ileus (POI) is a common complication after abdominal surgery. However, the risk factors for POI after laparoscopic colorectal resection are unclear. We therefore investigated the risk factors for POI after laparoscopic colorectal surgery.

Methods

This retrospective study involved 484 patients who underwent laparoscopic surgery for primary colorectal cancer at Hokkaido University Hospital. We categorized the patients into a POI group (n = 19) and non-POI group (n = 465). We compared sex, age, smoking, chronic obstructive pulmonary disease (COPD), diabetes mellitus, body mass index (BMI), cardiac disorder, serum albumin, American Society of Anesthesiologists-physical status, tumor location, tumor stage, operative duration, stoma formation, lymph node dissection, operator, and bleeding as potential risk factors for POI between the POI group and non-POI group by univariate and multivariate analyses.

Results

The univariate analysis results showed that the POI group had a higher incidence of male sex (P = 0.036), COPD (P = 0.029), and a BMI of <20 kg/m2 (P = 0.0487) as well as a higher bleeding volume (P = 0.014). The multivariate analysis results showed that male sex (odds ratio [OR], 0.2799; 95% confidence interval [CI], 0.089-0.993; P = 0.0298), COPD (0.2866; 0.095-0.862; P = 0.0262), and a BMI of <20 kg/m2 (0.2985; 0.112-0.794; P = 0.0154) were independent risk factors for POI after laparoscopic colorectal resection.

Conclusion

Our findings suggest that male sex, COPD, and a BMI of <20 kg/m2 are independent risk factors for POI after laparoscopic colorectal surgery for treatment of colorectal cancer.

Feasibility of Laparoscopic and Robotic Total Proctocolectomy for Ulcerative Colitis-related Colorectal Cancer

BACKGROUND/AIM

To evaluate the feasibility of laparoscopic and robotic total proctocolectomy (TPC) for ulcerative colitis-associated colorectal cancer (UC-CRC).

PATIENTS AND METHODS

We retrospectively analyzed the postoperative outcomes of TPC in 13 patients with UC-CRC between January 2011 and December 2021. Laparoscopic TPC was performed in 10 patients. TPC consisted of two procedures: ileal pouch-anal anastomosis (IAA) and TPC with end ileostomy. Using the da Vinci Xi platform with six ports, robotic TPC and abdominal perineal resection (APR) were performed in two and one patients, respectively. Transanal total mesorectal excision (TaTME) was performed using the perineal approach in five patients.

RESULTS

UC-CRC was located in the transverse colon, sigmoid colon, rectum, and anal canal in 1, 1, 10, and 1 patients, respectively. IAA, TPC with end ileostomy, and APR were performed in nine, three, and one patients, respectively. Postoperative complications included colitis, portal vein thrombosis, and liver dysfunction, without mortality. The pathological stages were 0, I, IIa, IIIb, and IIIc in five, four, one, two, and one patients, respectively. The tumors were completely resected in all cases. Eleven patients with pStages 0, I, and II survived without recurrence; however, two patients with pStage III died of cancer recurrence.

CONCLUSION

This study demonstrated the feasibility of laparoscopic and robotic TPC in patients with UC-CRC. However, long-term outcomes in terms of oncology and patient quality of life must be investigated in future large-scale studies.

Exploration of Optimal pH in Hypothermic Machine Perfusion for Rat Liver Grafts Retrieved after Circulatory Death

Ex vivo hypothermic machine perfusion (HMP) is a strategy for controlling ischemia-reperfusion injury in donation after circulatory death (DCD) liver transplantation. The pH of blood increases with a decrease in temperature and water dissociation, leading to a decrease in [H⁺]. This study aimed to verify the optimal pH of HMP for DCD livers. Rat livers were retrieved 30 min post-cardiac arrest and subjected to 3-h cold storage (CS) in UW solution (CS group) or HMP with UW-gluconate solution (machine perfusion [MP] group) of pH 7.4 (original), 7.6, 7.8, and 8.0 (MP-pH 7.6, 7.8, 8.0 groups, respectively) at 7-10 °C. The livers were subjected to normothermic perfusion to simulate reperfusion after HMP. All HMP groups showed greater graft protection compared to the CS group due to the lower levels of liver enzymes in the former. The MP-pH 7.8 group showed significant protection, evidenced by bile production, diminished tissue injury, and reduced flavin mononucleotide leakage, and further analysis by scanning electron microscopy revealed a well-preserved structure of the mitochondrial cristae. Therefore, the optimum pH of 7.8 enhanced the protective effect of HMP by preserving the structure and function of the mitochondria, leading to reduced reperfusion injury in the DCD liver.

Combination of Cold Storage in a Heavy Water-Containing Solution and Post-Reperfusion Hydrogen Gas Treatment Reduces Ischemia-Reperfusion Injury in Rat Livers

We previously reported the efficacy of cold storage (CS) using a heavy water-containing solution (Dsol) and post-reperfusion hydrogen gas treatment separately. This study aimed to clarify the combined effects of these treatments. Rat livers were subjected to 48-hour CS and a subsequent 90-minute reperfusion in an isolated perfused rat liver system. The experimental groups were the immediately reperfused control group (CT), the CS with University of Wisconsin solution (UW) group, the CS with Dsol group, the CS with UW and post-reperfusion H₂ treatment group (UW-H₂), and the CS with Dsol and post-reperfusion H₂ group (Dsol-H₂). We first compared the Dsol-H₂, UW, and CT groups to evaluate this alternative method to conventional CS. The protective potential of the Dsol-H₂ group was superior to that of the UW group, as evidenced by lower portal venous resistance and lactate dehydrogenase leakage, a higher oxygen consumption rate, and increased bile production. Multiple comparison tests among the UW, Dsol, UW-H₂, and Dsol-H₂ groups revealed that both treatments, during CS and after reperfusion, conferred a similar extent of protection and showed additive effects in combination therapy. Furthermore, the variance in all treatment groups appeared smaller than that in the no-treatment or no-stress groups, with excellent reproducibility. In conclusion, combination therapy with Dsol during CS and hydrogen gas after reperfusion additively protects against graft injury.

Warm Ischemia Induces Spatiotemporal Changes in Lysophosphatidylinositol That Affect Post-Reperfusion Injury in Normal and Steatotic Rat Livers

Warm ischemia-reperfusion injury is a prognostic factor for hepatectomy and liver transplantation. However, its underlying molecular mechanisms are unknown. This study aimed to elucidate these mechanisms and identify the predictive markers of post-reperfusion injury. Rats with normal livers were subjected to 70% hepatic warm ischemia for 15, 30, or 90 min, while those with steatotic livers were subjected to 70% hepatic warm ischemia for only 30 min. The liver and blood were sampled at the end of ischemia and 1, 6, and 24 h after reperfusion. The serum alanine aminotransferase (ALT) activity, Suzuki injury scores, and lipid peroxidation (LPO) products were evaluated. The ALT activity and Suzuki scores increased with ischemic duration and peaked at 1 and 6 h after reperfusion, respectively. Steatotic livers subjected to 30 min ischemia and normal livers subjected to 90 min ischemia showed comparable injury. A similar trend was observed for LPO products. Imaging mass spectrometry of normal livers revealed an increase in lysophosphatidylinositol (LPI (18:0)) and a concomitant decrease in phosphatidylinositol (PI (18:0/20:4)) in Zone 1 (central venous region) with increasing ischemic duration; they returned to their basal values after reperfusion. Similar changes were observed in steatotic livers. Hepatic warm ischemia time-dependent acceleration of PI (18:0/20:4) to LPI (18:0) conversion occurs initially in Zone 1 and is more pronounced in fatty livers. Thus, the LPI (18:0)/PI (18:0/20:4) ratio is a potential predictor of post-reperfusion injury.

Rapid and Reliable Steatosis Rat Model Shrsp5-Dmcr for Cold Storage Experiment

Interventions for liver grafts with moderate macrovesicular steatosis have been important in enlarging donor pools. Here, we tested a high-fat and cholesterol (HFC) diet to create a steatosis model for cold hepatic preservation and reperfusion experiments. The aim of the present study was to assess the steatosis model's reliability and to show the resulting graft's quality for cold preservation and reperfusion experiment. Male SHRSP5-Dmcr rats were raised with an HFC diet for up to 2 weeks. The fat content was evaluated using magnetic resonance imaging (MRI) proton density fat fraction (PDFF). The nonalcoholic fatty liver disease activity score (NAS) was evaluated after excision. Steatosis created by 2 weeks of HFC diet was subjected to 24-hour cold storage in the University of Wisconsin and the original test solution (new sol.). Grafts were applied to isolated perfused rat livers for simulating reperfusion. The NAS were 2.2 (HFC 5 days), 3.3 (HFC 1 week), and 5.0 (HFC 2 weeks). Ballooning and fibrosis were not observed in any group. An MRI-PDFF showed 0.2 (HFC 0 days), 12.0 (HFC 1 week), and 18.9 (HFC 2 weeks). The NAS and MRI-PDFF values correlated. Many indices in the isolated perfused rat liver experiment tended to improve in the new sol. group but were insufficient. Although the new sol. failed to be effective, it acted at multiple sites under difficult conditions. In conclusion, the HFC diet for 2 weeks in SHRSP5-Dmcr rats, together with MRI-PDFF evaluation, is a reliable method for creating simple steatosis and provides good-quality cold preservation and reperfusion experiments.

Hypothermic Machine Perfusion with Hydrogen Gas Reduces Focal Injury in Rat Livers but Fails to Restore Organ Function

BACKGROUND

We have previously reported the efficacy of post-reperfusion H₂ gas treatment in cold storage (CS) and subsequent reperfusion of the rat liver. The present study aimed to evaluate the effect of H₂ gas treatment during hypothermic machine perfusion (HMP) in rat livers retrieved from donation after circulatory death (DCD) and elucidate the mechanism of action of H₂ gas.

METHODS

Liver grafts were procured from rats after 30 min of cardiopulmonary arrest. The graft was subjected to HMP for 3 hours at 7°C using Belzer MPS with or without dissolved H₂ gas. The graft was reperfused using an isolated perfused rat liver apparatus at 37°C for 90 minutes. Perfusion kinetics, liver damage, function, apoptosis, and ultrastructure were evaluated.

RESULTS

Portal venous resistance, bile production, and oxygen consumption rates were identical in the CS, MP, and MP-H₂ groups. Liver enzyme leakage was suppressed by MP (vs control), whereas H₂ treatment did not show a combination effect. Histopathology revealed poorly stained areas with a structural deformity just below the liver surface in the CS and MP groups, whereas these findings disappeared in the MP-H₂ group. The apoptotic index in the CS and MP groups was high but decreased in the MP-H₂ group. Mitochondrial cristae were damaged in the CS group but preserved in the MP and MP-H₂ groups.

CONCLUSIONS

In conclusion, HMP and H₂ gas treatment are partly effective in DCD rat livers but insufficient. Hypothermic machine perfusion can improve focal microcirculation and preserve mitochondrial ultrastructure.

Layered β-ZrNBr Nitro-Halide as Multifunctional Photocatalyst for Water Splitting and CO2 Reduction

Developing mixed-anion semiconductors for solar fuel production has inspired extensive interest, but the nitrohalide-based photocatalyst is still in shortage. Here we report a layered nitro-halide β-ZrNBr with a narrow band gap of ca. 2.3 eV and low defect density to exhibit multifunctionalities for photocatalytic water reduction, water oxidation and CO₂ reduction under visible-light irradiation. As confirmed by the results of electron paramagnetic resonance (EPR) and density functional theory (DFT) calculations, the formation of anion vacancies in the nitro-halide photocatalyst was inhibited due to its relatively high formation energy. Furthermore, performance of β-ZrNBr can be effectively promoted by a simple exfoliation into nanosheets to shorten the carrier transfer distance as well as to promote charge separation. Our work extends the territory of functional photocatalysts into the nitro-halide, which opens a new avenue for fabricating efficient artificial photosynthesis.

Two-time perforation of the ileal J-pouch 6 and 18 years after restorative proctocolectomy and ileal pouch–anal anastomosis for familial adenomatous polyposis: a case report

Background

Perforation of the ileal J-pouch after restorative proctocolectomy and ileal pouch–anal anastomosis are extremely rare. There has been no report of perforation of the ileal J-pouch occurring twice over several years. We report the first case of perforation at 6 and 18 years following restorative proctocolectomy.

Case presentation

The patient was a 52-year-old man who underwent a two-stage restorative proctocolectomy with a hand-sewn ileal J-pouch anal anastomosis due to familial adenomatous polyposis and sigmoid colon cancer at 34 years of age. At the age of 40, he underwent ileal pouch resection at its blind end, abdominal drainage, and anastomotic dilatation. The patient had a perforation of the blind end of the ileal J-pouch from increased intraluminal pressure, with anastomotic stricture and pervasive peritonitis. The patient had no symptoms for a few years; however, 18 years after the initial surgery and 12 years after the first perforation, the patient presented with severe abdominal pain. Computed tomography demonstrated pneumoperitoneum; accordingly, laparotomy was performed. Upon opening the abdominal cavity, contaminated ascites and inflammatory changes were documented involving the ileum. A 2-mm perforation involving the blind end of the ileal J-pouch was also observed and repaired, followed by temporary loop ileostomy creation. Postoperative endoscopy revealed an ulcer in the ileal J-pouch and a stricture located directly at the anastomosis.

Conclusions

The blind end of the J-pouch repeatedly perforated over the years due to recurrent anastomotic stricture. Regular surveillance is, therefore, considered necessary for the release of stricture, maintenance of anastomotic patency, and prevention of ileal J-pouch perforation.

Direct visualization of the three-dimensional shape of skyrmion strings in a noncentrosymmetric magnet

Magnetic skyrmions are topologically stable swirling spin textures that appear as particle-like objects in two-dimensional (2D) systems. Here, utilizing scalar magnetic X-ray tomography under applied magnetic fields, we report the direct visualization of the three-dimensional (3D) shape of individual skyrmion strings in the room-temperature skyrmion-hosting non-centrosymmetric compound Mn_1.4Pt_0.9Pd_0.1Sn. Through the tomographic reconstruction of the 3D distribution of the [001] magnetization component on the basis of transmission images taken at various angles, we identify a skyrmion string running through the entire thickness of the sample, as well as various defect structures, such as the interrupted and Y-shaped strings. The observed point defect may represent the Bloch point serving as an emergent magnetic monopole, as proposed theoretically. Our tomographic approach with a tunable magnetic field paves the way for direct visualization of the structural dynamics of individual skyrmion strings in 3D space, which will contribute to a better understanding of the creation, annihilation and transfer of these topological objects.

Rapid vigilance and episodic memory decrements in COVID-19 survivors

Recent studies indicate that COVID-19 infection can lead to serious neurological consequences in a small percentage of individuals. However, in the months following acute illness, many more suffer from fatigue, low motivation, disturbed mood, poor sleep and cognitive symptoms, colloquially referred to as 'brain fog'. But what about individuals who had asymptomatic to moderate COVID-19 and reported no concerns after recovering from COVID-19? Here, we examined a wide range of cognitive functions critical for daily life (including sustained attention, memory, motor control, planning, semantic reasoning, mental rotation and spatial-visual attention) in people who had previously suffered from COVID-19 but were not significantly different from a control group on self-reported fatigue, forgetfulness, sleep abnormality, motivation, depression, anxiety and personality profile. Reassuringly, COVID-19 survivors performed well in most abilities tested, including working memory, executive function, planning and mental rotation. However, they displayed significantly worse episodic memory (up to 6 months post-infection) and greater decline in vigilance with time on task (for up to 9 months). Overall, the results show that specific chronic cognitive changes following COVID-19 are evident on objective testing even amongst those who do not report a greater symptom burden. Importantly, in the sample tested here, these were not significantly different from normal after 6-9 months, demonstrating evidence of recovery over time.

Action video game play facilitates "learning to learn"

Previous work has demonstrated that action video game training produces enhancements in a wide range of cognitive abilities. Here we evaluate a possible mechanism by which such breadth of enhancement could be attained: that action game training enhances learning rates in new tasks (i.e., "learning to learn"). In an initial controlled intervention study, we show that individuals who were trained on action video games subsequently exhibited faster learning in the two cognitive domains that we tested, perception and working memory, as compared to individuals who trained on non-action games. We further confirmed the causal effect of action video game play on learning ability in a pre-registered follow-up study that included a larger number of participants, blinding, and measurements of participant expectations. Together, this work highlights enhanced learning speed for novel tasks as a mechanism through which action video game interventions may broadly improve task performance in the cognitive domain.

Khorana score at an initial chemotherapy is effective on predicting death in patients with gastrointestinal cancer

Background

The Khorana risk score (KRS) has been recommended for predicting an incidence of cancer-associated thrombosis (CAT). On the other hand, KRS is that the specific gravity of score for the primary tumor is too high and the prevalence of severe obesity is low, so there are some reports that the KRS is not effective in predicting CAT but is effective in predicting death.

Purpose

The purpose of this retrospective cohort study was to evaluate the efficacy of KRS on predicting CAT and all-cause death at an initial chemotherapy in patients with gastrointestinal cancer.

Methods

260 consecutive patients with no history of thrombosis who started an initial chemotherapy for gastrointestinal cancer during a 2-year period from January 2017 to December 2018 in our hospital were divided into 3 groups according to KRS and observed until December 2019 (122 patients (46.9%) in the low-risk group (0 points), 114 patients (43.8%) in the intermediate-risk group (1–2 points), and 24 patients (9.2%) in the high-risk group (3–6 points)). The incidence of CAT and all-cause death was compared among 3 groups.

Results

The median age of the patients was 67 (60–75) years, and 63.5% of them were male. CAT was observed in 61 patients (23.5%), and 84 patients (32.3%) died during the observation period. There was no difference in the incidence rate of CAT among 3 groups (Log-rank P=0.6), but all-cause death was a significant difference among 3 groups (high risk group: 54.2%, intermediate risk group: 36.0%, low risk group: 24.6%, p value=0.0023). After adjustment for multivariate analysis, the KRS high risk group was still significantly associated with death (HR: 2.83, 95% CI: 1.37–5.83, p value =0.0049), but not with CAT.

Conclusion

The Khorana score at an initial of chemotherapy in patients with gastrointestinal cancer is useful in predicting prognosis, but not CAT.

Funding Acknowledgement

Type of funding sources: None.

Electrochemical Crystal Growth of Titanium Oxyfluorides-A Strategy for Development of Electron-Doped Materials

We report on the growth of single crystals of an electron-doped titanium oxyfluoride, Li₂Ti(O,F)₃, employing high-temperature electrolysis of TiO₂ with a eutectic Li₂MoO₄-LiF melt. Greenish octahedral-shaped crystals (∼30 μm in size) with a cubic rocksalt-type structure were successfully obtained by precisely tuning the applied voltage. The temperature-dependent magnetic susceptibility data revealed a paramagnetic behavior at low temperatures, ensuring the presence of Ti³⁺ ions (mean valence number of +3.78; F/Ti ∼ 0.15). The crystals exhibited clear visible-light absorption and produced H₂ from water in the presence of a sacrificial reagent under UV-light irradiation. Li₂Ti(O,F)₃ more efficiently produced H₂ compared with a nondoped oxyfluoride Li₅Ti₂O₆F, likely due to the doped electrons for the former. This work highlights a promising electrochemical approach toward growing electron-doped oxyfluoride crystals.

The Phenolic Antioxidant 3,5-dihydroxy-4-methoxybenzyl Alcohol (DHMBA) Prevents Enterocyte Cell Death under Oxygen-Dissolving Cold Conditions through Polyphyletic Antioxidant Actions

Cold preservation in University of Wisconsin (UW) solution is not enough to maintain the viability of the small intestine, due to the oxidative stress. The novel phenolic antioxidant 3,5-dihydroxy-4-methoxybenzyl alcohol (DHMBA) has dual properties to reduce oxidative stress, radical scavenging, and antioxidant protein induction, in other cells. This study was designed to determine whether DHMBA reduces cold preservation injury of enterocytes, and to identify the effector site. Enterocytes were subjected to 48-h cold preservation under atmosphere in UW solution (±DHMBA), and then returned to normal culture to replicate reperfusion of the small intestine after cold preservation. At the end of cold preservation (ECP) and at 1, 3, 6, and 72 h after rewarming (R1h, R3h, R6h, and R72h), we evaluated cell function and the injury mechanism. The results showed that DHMBA protected mitochondrial function mainly during cold preservation, and suppressed cell death after rewarming, as shown by the MTT, ATP, mitochondrial membrane potential, LDH, and lipid peroxidation assays, together with enhanced survival signals (PI3K, Akt, p70S6K) and induction of antioxidant proteins (HO-1, NQO-1, TRX-1). We found that DHMBA mitigates the cold-induced injury of enterocytes by protecting the mitochondria through direct and indirect antioxidative activities.

Clinical implication of symptom for long-term outcomes after elective percutaneous coronary intervention

Background

The appropriate treatment for silent myocardial ischemia (SMI) is controversial. The prognosis of asymptomatic patients after percutaneous coronary intervention (PCI) is unknown. Asymptomatic patients might be sicker and have delay of diagnosis when they have coronary events in clinical course. We, thus, hypothesized SMI are associate with the poor outcomes after PCI for stable coronary artery disease (CAD).

Purpose

The present study compared the long-term outcomes of patients with SMI vs. stable angina pectoris (SAP) after elective PCI.

Methods

Our prospective registry database included 923 consecutive patients with CAD who underwent PCI from October 2015 to August 2018. Patients with emergent PCI, acute coronary syndrome at admission, or chronic total occlusion patients were not included. A total 613 patients (71.4±11.2 years, 75.7% male) who underwent elective PCI were studied. The end points included all-cause mortality, non-fatal myocardial infarction, and repeat revascularization.

Results

They were divided into 2 groups according to symptom status: SMI (n=392) and SAP (n=221). SMI patients were predominantly men, and more frequently had diabetes mellitus (197 [50.4%] vs. 91 [41.2%], p=0.028), previous myocardial infarction (44 [11.3%] vs. 8 [3.6%], p=0.001) and heart failure hospitalization.Echocardiography showed SMI groups had reduced ejection fraction (56.9±12.6 vs 63.3±9.1, P&lt;0.001), extended left ventricular internal dimension in diastole (48.5±6.2 vs 47.4±5.8, p=0.048) and left ventricular diameter at end systole (32.8±7.6 vs 30.5±7.5, p=0.001). Mean duration of follow-up was 20.9±10.6 months. The incidence of non-fatal myocardial infarction and repeat revascularization was similar between the 2 groups (10 [2.6%] vs. 5 [2.3%], p=0.82, and 50 [12.8%] vs. 30 [13.6%], p=0.77, respectively). The incidence of all-cause and cardiovascular mortality was more frequent in SMI patients (26 [6.6%] vs. 6 [2.7%], p=0.036, and 9 [3.1%] vs 1 [0.5%], p=0.035, respectively). Kaplan-Meier survival curves indicated that SMI patients had significantly higher all cause-mortality than SAP patients (log-rank, p=0.0184, Hazard ratio 1.24 (1.05–1.47), p=0.013). In multivariable analysis, SMI was an independent predictor of all cause-mortality (Hazard-ratio 5.17, 95% CI 1.35–34.29, p=0.014).

Conclusion

In patients with stable CAD undergoing elective PCI, SMI was associated with an increase in mortality. Optimal care for SMI patients after PCI should be clarified in future studies.

Funding Acknowledgement

Type of funding source: None

Safety and efficacy of a hyperaemic agent, intracoronary nicorandil 4mg, for invasive physiological assessments during fractional flow reserve measurement

Background

Fractional flow reserve (FFR) is one of most reliable index for the determining the functional severity coronary artery stenosis. Adenosine is the most commonly used agent for maximal hyperaemia. However, adenosine can cause chest discomfort, bronchial hyper-reactivity, and atrioventricular block. The aim of this study is to evaluate the safety and efficacy of intracoronary nicorandil as an alternative hyperaemic agent for FFR.

Methods and results

We enrolled consecutive 82 patients (87 lesions) who underwent FFR measurement in our center from Nov. 2018. We compared three groups; intravenous infusion of adenosine (150 μg/kg/min); and adenosine added intracoronary nicorandil 2mg; and intracoronary nicorandil 4mg. Mean FFR value was 0.83±0.09, 0.82±0.09, 0.82±0.08, There was a strong correlation among three groups (R2&gt;0.9). Mean cyclic change in FFR was 0.026±0.023, 0.019±0.010, 0.016±0.014, respectively, cyclic change was smallest in intracoronary nicorandil 4mg group (vs ATP; p&lt;0.001, vs ATP + nicorandil 2mg; p&lt;0.001). By Wilcoxon test, mean FFR value of nicorandil 4mg was significant lower than ATP (p=0.0021), and equal to ATP + nicorandil 2mg (p=0.98).

Conclusions

Intracoronary nicorandil 4mg is a simple, safe, and effective way to induce steady-state hyperaemia for FFR.

Figure 1

Funding Acknowledgement

Type of funding source: None

Changes in nutritional status by recovery phase interventions would be a powerful determinant of cardiovascular prognosis in heart failure patients

Background

Adequate nutrition has been proposed for better cardiovascular prognosis as well as fitness, although the impact of the “changes” in nutrition and fitness at recovery phase on the future prognosis has been unclear.

Purpose

We aimed to examine whether the change in nutritional level as a result of dietary intervention combined with exercise would determine patients' cardiovascular prognosis.

Methods

This study involved 398 consecutive patients who participated in phase II comprehensive cardiac rehabilitation (CCR) for at least three months. All patients underwent cardiopulmonary exercise test (CPX) at the initial and completion periods of CCR. Individual dietary guidance was periodically performed with exercise. Peak oxygen uptake (PVO2) was measured through CPX to evaluate the fitness level, whereas nutritional status was evaluated using the geriatric nutritional risk index (GNRI). Patients were divided in two groups according to the baseline GNRI and the change in GNRI (ΔGNRI) by the median, respectively, to compare their prognosis between groups. Then they were classified into four categories according to the median values of the changes in GNRI (ΔGNRI) and PVO2 (ΔPVO2) during CCR: “Both improved”, “Only GNRI improved”, “Only PVO2 improved” and “Both NOT improved”, to compare MACCE-free rate between categories.

Results

The rate of MACCE showed significant difference between categories (14%, 18%, 19% and 36%, p&lt;0.001), which was approximately 2 times higher in “Both NOT improved” than the others. Kaplan-Meier analysis showed that according to the level of ΔGNRI, “higher ΔGNRI group” showed significantly higher in MACCE-free survival rate than “lower ΔGNRI group” (log rank p=0.010), whereas there was no significant difference according to the baseline GNRI (see figure). According to the categories divided by ΔGNRI and ΔPVO2, MACCE-free rate was significantly lower in “Both NOT improved” (log rank p&lt;0.001) compared to the other categories. Cox proportional hazard regression analysis revealed that “both NOT improved” was an independent predictor of MACCE (hazard ratio, 2.1, 95% confident interval, 1.344–3.175, p&lt;0.001).

Conclusion

Changes in nutritional level would determine patients' cardiovascular prognosis rather than the baseline nutritional level. Non-responders who showed no improvement in nutritional or fitness by interventions may result in a poor cardiovascular outcome.

Funding Acknowledgement

Type of funding source: None

Intestinal anisakiasis with severe intestinal ischemia caused by extraluminal live larvae: a case report

Background

Anisakiasis is a parasitic infection caused by Anisakis worms found in raw fish. Most cases of anisakiasis occur in the stomach and rarely occur in the intestine. It is extremely rare for live larvae to break through the intestine into the mesentery and cause severe intestinal ischemia. Anisakiasis can be treated conservatively, because the larvae will die in approximately 1 week, but, sometimes, a serious condition can arise, as in this case. We report the first case of extraluminal anisakiasis in which a live Anisakis worm caused severe intestinal ischemia.

Case presentation

The patient was a 26-year-old woman who ate squid a week prior. She had abdominal pain and was admitted to our emergency department. On physical examination, abdominal guarding and rebound tenderness were present in her lower abdomen. Contrast-enhanced computed tomography showed ascites, the whirl sign, localized submucosal edema of the intestinal wall, and a dilated small bowel segment with edema. We suspected the strangulated small bowel obstruction based on the CT-scan findings. To rule out the strangulated small bowel obstruction, laparoscopic exploration was performed. Bloody ascites in the pouch of Douglas and severe inflammation in 20 cm of the ileum were observed. An Anisakis larva had perforated the intestinal wall and was found alive in the mesentery. The ileum had developed a high degree of ischemia, so the affected section was resected. Histopathological examination revealed that the Anisakis worm body was in the inflamed mesentery and caused a high degree of ischemia in the intestinal tract. The patient was discharged 9 days after surgery.

Conclusions

A living Anisakis larva punctured the mesentery of the small intestine, resulting in severe intestinal ischemia. As seen in this case, intestinal anisakiasis may cause serious symptoms, and a low threshold for performing diagnostic laparoscopy for the early diagnosis of bowel ischemia secondary to anisakiasis can be useful in determining the definite diagnosis and indications for resection.

Imaging Mass Spectrometry Reveals the Changes in the Taurine Conjugates of Dihydroxycholanoic Acid During Hepatic Warm Ischemia and Reperfusion in a Rat Model

Warm ischemia and reperfusion injury (IRI) is a prognostic factor in donation after cardiac death donor transplantation. However, a reliable method to predict IRI before transplantation has not been established. The aim of this study was to identify predictive markers of hepatic IRI by simultaneous measurement of endogenous molecules using matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS). Rats were subjected to hepatic warm ischemia (70%) for 30 or 90 minutes and subsequent reperfusion. The livers were collected at the end of ischemia and 1 hour, 6 hours, and 24 hours after reperfusion. The liver tissue sections were applied to IMS (m/z 200-2000). Candidate molecules were identified by tandem mass spectrometry. Imaging mass spectrometry (IMS) revealed a significant increase in the taurine conjugates of dihydroxycholanoic acid (TDHCA) during ischemia and a tendency to return to the basal level after reperfusion. Notably, high-resolution measurements revealed focal accumulation of TDHCA in the intrahepatic bile duct with ischemic time. In conclusion, IMS is a useful method to detect minute changes provoked by ischemia, which are barely detectable in assays involving homogenization. Accordingly, focal accumulation of TDHCA during ischemia may be a candidate marker for predicting later IRI.

Motion tracking of 80-nm-size skyrmions upon directional current injections

Nanometer-scale skyrmions are prospective candidates for information bits in low-power consumption devices owing to their topological nature and controllability with low current density. Studies on skyrmion dynamics in different classes of materials have exploited the topological Hall effect and current-driven fast motion of skyrmionic bubbles. However, the small current track motion of a single skyrmion and few-skyrmion aggregates remains elusive. Here, we report the tracking of creation and extinction and motion of 80-nm-size skyrmions upon directional one-current pulse excitations at low current density of the order of 109 A m-2 in designed devices with the notched hole. The Hall motion of a single skyrmion and the torque motions of few-skyrmion aggregates have been directly revealed. The results exemplify low-current density controls of skyrmions, which will pave the way for the application of skyrmions.

An fMRI Study of the Brain Network Involved in Teeth Tapping in Elderly Adults

Cortical activity during jaw movement has been analyzed using various non-invasive brain imaging methods, but the contribution of orofacial sensory input to voluntary jaw movements remains unclear. In this study, we used functional magnetic resonance imaging (fMRI) to observe brain activities during a simple teeth tapping task in adult dentulous (AD), older dentulous (OD), and older edentulous subjects who wore dentures (OEd) or did not wear dentures (OE) to analyze their functional network connections. (1) To assess the effect of age on natural activation patterns during teeth tapping, a comparison of groups with natural dentition—AD and OD—was undertaken. A general linear model analysis indicated that the major activated site in the AD group was the primary sensory cortex (SI) and motor cortex (MI) (p < 0.05, family wise error corrected). In the OD group, teeth tapping induced brain activity at various foci (p < 0.05, family wise error corrected), including the SI, MI, insula cortex, supplementary motor cortex (SMC)/premotor cortex (PMA), cerebellum, thalamus, and basal ganglia in each group. (2) Group comparisons between the OD and OEd subjects showed decreased activity in the SI, MI, Brodmann’s area 6 (BA6), thalamus (ventral posteromedial nucleus, VPM), basal ganglia, and insular cortex (p ¡ 0.005, uncorrected). This suggested that the decreased S1/M1 activity in the OEd group was related to missing teeth, which led to reduced periodontal afferents. (3) A conjunction analysis in the OD and OEd/OE groups revealed that commonly activated areas were the MI, SI, cerebellum, BA6, thalamus (VPM), and basal ganglia (putamen; p < 0.05, FWE corrected). These areas have been associated with voluntary movements. (4) Psychophysiological interaction analysis (OEd vs OE) showed that subcortical and cortical structures, such as the MI, SI, DLPFC, SMC/PMA, insula cortex, basal ganglia, and cerebellum, likely function as hubs and form an integrated network that participates in the control of teeth tapping. These results suggest that oral sensory inputs are involved in the control of teeth tapping through feedforward control of intended movements, as well as feedback control of ongoing movements.

Final overall survival results of WJTOG3405, a randomized phase III trial comparing gefitinib versus cisplatin with docetaxel as the first-line treatment for patients with stage IIIB/IV or postoperative recurrent EGFR mutation-positive non-small-cell lung cancer

BACKGROUND

Primary analysis of the phase III study WJTOG 3405 demonstrated superiority of progression-free survival (PFS) for gefitinib (G) in patients treated with the epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) gefitinib compared with cisplatin plus docetaxel (CD) as the first-line treatment of stage IIIB/IV or postoperative recurrent EGFR mutation-positive non-small-cell lung cancer. This report presents final overall survival (OS) data.

PATIENTS AND METHODS

Patients were randomized between G (250 mg/day orally) and cisplatin (80 mg/m2 intravenously) plus docetaxel (60 mg/m2 i.v.), administered every 21 days for three to six cycles. After the exclusion of 5 patients, 172 patients (86 in each group, modified intention-to-treat population) were included in the survival analysis. OS was re-evaluated using updated data (data cutoff, 30 September 2013; median follow-up time 59.1 months). The Kaplan-Meier method and the log-rank test were used for analysis, and hazard ratios (HRs) for death were calculated using the Cox proportional hazards model.

RESULTS

OS events in the G group and CD group were 68 (79.1%) out of 86 and 59 (68.6%) out of 86, respectively. Median survival time for G and CD were 34.9 and 37.3 months, respectively, with an HR of 1.252 [95% confidence interval (CI): 0.883-1.775, P = 0.2070]. Multivariate analysis identified postoperative recurrence and stage IIIB/IV disease as independent prognostic factors, with an HR of 0.459 (95% CI: 0.312-0.673, P < 0.001). Median survival time (postoperative recurrence versus stage IIIB/IV disease) were 44.5 and 27.5 months in the G group and 45.5 and 32.8 months in the CD group, respectively.

CONCLUSION

G did not show OS benefits over CD as the first-line treatment. OS of patients with postoperative recurrence was better than that of stage IIIB/IV disease, even though both groups had metastatic disease.This study was registered with UMIN (University Hospital Medical Information Network in Japan), number 000000539.

Heavy Water (D2O) Containing Preservation Solution Reduces Hepatic Cold Preservation and Reperfusion Injury in an Isolated Perfused Rat Liver (IPRL) Model

Background: Heavy water (D₂O) has many biological effects due to the isotope effect of deuterium. We previously reported the efficacy of D₂O containing solution (Dsol) in the cold preservation of rat hearts. Here, we evaluated whether Dsol reduced hepatic cold preservation and reperfusion injury. Methods: Rat livers were subjected to 48-hour cold storage in University of Wisconsin (UW) solution or Dsol, and subsequently reperfused on an isolated perfused rat liver. Graft function, injury, perfusion kinetics, oxidative stress, and cytoskeletal integrity were assessed. Results: In the UW group, severe ischemia and reperfusion injury (IRI) was shown by histopathology, higher liver enzymes leakage, portal resistance, and apoptotic index, oxygen consumption, less bile production, energy charge, and reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio (versus control). The Dsol group showed that these injuries were significantly ameliorated (versus the UW group). Furthermore, cytoskeletal derangement was progressed in the UW group, as shown by less degradation of α-Fodrin and by the inactivation of the actin depolymerization pathway, whereas these changes were significantly suppressed in the Dsol group. Conclusion: Dsol reduced hepatic IRI after extended cold preservation and subsequent reperfusion. The protection was primarily due to the maintenance of mitochondrial function, cytoskeletal integrity, leading to limiting oxidative stress, apoptosis, and necrosis pathways.

A zinc-based oxysulfide photocatalyst SrZn2S2O capable of reducing and oxidizing water

Although Zn-based binary semiconductors such as ZnO and ZnS are photocatalytically unstable toward water oxidation, we found that mixed-anionization successfully addressed this issue. This report shows that an oxysulfide SrZn₂S₂O functions as a photocatalyst to reduce and oxidize water under band-gap irradiation without noticeable decomposition of the material.

P2528Responsiveness to nutritional intervention would impact on future cardiovascular prognosis in poor fitness patients

Purpose

Nutritional improvement has been proposed for long-term cardiovascular prognosis as well as fitness recovery. We aimed to examine whether “responsiveness” to nutritional and exercise interventions would impact patients' cardiovascular prognosis even patients in low baseline fitness level.

Methods

We included 254 consecutive patients who participated in the phase II comprehensive cardiovascular rehabilitation (CCR) for at least three months. All patients underwent cardiopulmonary exercise test (CPX) at the initial and completion phases of CCR. Nutritional guidance was periodically performed individually during CCR. Peak oxygen uptake (PVO2) was measured through CPX to evaluate the fitness level, whereas nutritional status was evaluated using the geriatric nutritional risk index (GNRI). Patients were divided into “low fitness” and “normal fitness” groups based on the median of baseline PVO2. Each group was further classified into four categories according to the changes in VO2 and GNRI during CCR: “Both NOT improved”, “Only GNRI improved”, “Only PVO2 improved”, and “Both improved”.

Results

Cox proportional regression analysis showed that the category of “both NOT improved” was an independent predictor for cardiovascular risk among the baseline low fitness group (Hazard ratio: 4.5, p=0.007); whereas no significant difference among the normal fitness group. Kaplan-Meier analysis revealed that the event-free survival rate was significantly lower in the “both NOT improved” category (log rank p=0.002) among the baseline low fitness group (figure); whereas no significant difference among the normal fitness group.

GNRI/PVO2 improvement vs. prognosis

Conclusion

Responsiveness to nutritional and exercise intervention could be a predictive factor of cardiovascular prognosis even in low fitness patients.

Comparison of posterior alveolar canal location measured on computer tomography scan with cadaveric measurement of posterior superior alveolar foramen in Japanese samples

The aim of this study was to analyse anatomical characteristics of the most posterior alveolar canal (PAC) on computed tomography (CT) images and the posterior superior alveolar foramen (PSAF) physically identified in cadaveric samples, to avoid injuring the posterior superior alveolar artery (PSAA) during surgery in the maxillary tuberosity region. The study included 125 hemi-heads of 64 Japanese cadavers. Simple CT data of the maxillary bone region of the samples were obtained and analysed using measurement software. The alveolar crest (AC) and the PAC were identified to calculate the shortest distance between the AC and the PAC (AC-PAC). Then the samples were dissected to measure physically the shortest distance between the AC and the PSAF (AC-PSAF). The data were analysed statistically. The mean value and standard deviation were 20.7±4.2mm for AC-PAC and 20.7±4.3mm for AC-PSAF. The intraclass correlation coefficient between AC-PAC and AC-PSAF was 0.98. The CT-measured PAC locations were found to be almost identical to the PSAF positions identified physically in the samples. Preoperative CT localization of the PAC aids in avoiding injury to PSAA, while preoperative CT evaluation is important for each case due to significant individual variability in the anatomical PAC and PSAF locations.

Thermal behavior, structure, dynamic properties of aqueous glycine solutions confined in mesoporous silica MCM-41 investigated by x-ray diffraction and quasi-elastic neutron scattering

Differential scanning calorimetry, X-ray diffraction, and quasi-elastic neutron scattering (QENS) measurements of aqueous glycine solutions confined in mesoporous silica (MCM-41) were performed at different glycine concentrations, pH, and loading ratio (=mass of glycine solution/mass of dry MCM-41) in the temperature range from 305 to 180 K to discuss the confinement effect on the thermal behavior, the structure, and the dynamic properties of the solutions. The freezing points of the confined glycine solutions decreased, compared with those of the bulk solutions. The corresponding exothermic peak due to ice formation became broader with an increase in the glycine concentration. By subtracting X-ray diffraction patterns of dry MCM-41 from those of glycine solution-loaded MCM-41, information about the structure of the confined glycine solutions was obtained. The radial distribution functions of the confined glycine solutions showed that the peaks assigned to the interaction between glycine molecules and the surface silanol (Si-OH) groups of MCM-41 at pH = 5 were observed, in contrast to the case at pH = 2. The QENS data on H/D substituted aqueous glycine solutions gave the translational diffusion coefficients and the residence time of glycine and water molecules confined in MCM-41 individually. The activation energy of the diffusion coefficient of a glycine molecule at pH = 5 was larger than that at pH = 2. These results imply that glycine molecules locate near the pore surface of MCM-41 due to the formation of hydrogen bonding between glycine molecules and the silanol group of the MCM-41 wall at pH = 5.

Post-reperfusion hydrogen gas treatment ameliorates ischemia reperfusion injury in rat livers from donors after cardiac death: a preliminary study

BACKGROUND AND PURPOSE

We reported previously that hydrogen gas (H₂) reduced hepatic ischemia and reperfusion injury (IRI) after prolonged cold storage (CS) of livers retrieved from heart-beating donors. The present study was designed to assess whether H₂ reduced hepatic IRI during donation of a cardiac death (DCD) graft with subsequent CS.

METHODS

Rat livers were harvested after 30-min cardiac arrest and stored for 4 h in University of Wisconsin solution. The graft was reperfused with oxygenated buffer, with or without H₂ (H₂ or NT groups, respectively), at 37° for 90 min on isolated perfused rat liver apparatus.

RESULTS

In the NT group, liver enzyme leakage, apoptosis, necrosis, energy depletion, redox status, impaired microcirculation, and bile production were indicative of severe IRI, whereas in the H₂ group these impairments were significantly suppressed. The phosphorylation of cytoplasmic MKK4 and JNK were enhanced in the NT group and suppressed in the H₂ group. NFkB-p65 and c-Fos in the nucleus were unexpectedly unchanged by IRI regardless of H₂ treatment, indicating the absence of inflammation in this model.

CONCLUSION

H₂ was observed to ameliorate IRI in the DCD liver by maintaining microcirculation, mitochondrial functions, and redox status, as well as suppressing the cytoplasmic MKK4-JNK-mediated cellular death pathway.

Activation of NLRP3 inflammasome in macrophages by mycoplasmal lipoproteins and lipopeptides

The NLRP3 inflammasome, an intracellular sensor consisting of the nucleotide-binding oligomerization domain-like receptor family, pyrin domain containing 3 (NLRP3), the adaptor protein apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC), and procaspase-1, plays critical roles in host defense against microbial pathogens by inducing production of interleukin-1β (IL-1β) and IL-18. Mycoplasma salivarium and Mycoplasma pneumoniae cells activated murine bone marrow-derived macrophages (BMMs) to induce production of IL-1α, IL-1β, and IL-18. The IL-1β production-inducing activities of these mycoplasmas toward BMMs from Toll-like receptor 2 (TLR2)-deficient mice were significantly attenuated compared with those from C57BL/6 mice (B6BMMs). This result suggests the possibility that their lipoproteins as TLR2 agonists are involved in the activity. Lipoproteins of M. salivarium and M. pneumoniae (MsLP and MpLP), and the M. salivarium-derived lipopeptide FSL-1 induced IL-1β production by B6BMMs, but not by BMMs from caspase-1-, NLRP3- or ASC-deficient mice. The activities of MsLP and MpLP were not downregulated by the proteinase K treatment, suggesting that the active sites are their N-terminal lipopeptide moieties. B6BMMs internalized the mycoplasmal N-terminal lipopeptide FSL-1 at least 30 min after incubation, FSL-1-containing endosomes started to fuse with the lysosomes around 2 hours, and then FSL-1 translocated into the cytosol from LAMP-1⁺ endosomes. The artificial delivery of FSL-1 into the cytosol of B6BMMs drastically enhanced the IL-1β production-inducing activity. FSL-1 as well as the representative NLRP3 inflammasome activator nigericin induced the NLRP3/ASC speck, but FSL-1 located in a compartment different from the NLRP3/ASC speck.

Liquid-like thermal conduction in intercalated layered crystalline solids

As a generic property, all substances transfer heat through microscopic collisions of constituent particles ¹ . A solid conducts heat through both transverse and longitudinal acoustic phonons, but a liquid employs only longitudinal vibrations^2,3. As a result, a solid is usually thermally more conductive than a liquid. In canonical viewpoints, such a difference also serves as the dynamic signature distinguishing a solid from a liquid. Here, we report liquid-like thermal conduction observed in the crystalline AgCrSe₂. The transverse acoustic phonons are completely suppressed by the ultrafast dynamic disorder while the longitudinal acoustic phonons are strongly scattered but survive, and are thus responsible for the intrinsically ultralow thermal conductivity. This scenario is applicable to a wide variety of layered compounds with heavy intercalants in the van der Waals gaps, manifesting a broad implication on suppressing thermal conduction. These microscopic insights might reshape the fundamental understanding on thermal transport properties of matter and open up a general opportunity to optimize performances of thermoelectrics.

Curative resection of pancreatic ductal adenocarcinoma developing in the remnant pancreas 13 years after distal pancreatectomy for intraductal papillary mucinous neoplasms: A case report

Intraductal papillary mucinous neoplasms (IPMNs) are characterized by the papillary proliferation of atypical mucinous epithelial cells in the pancreatic ductal system. There are two recurrence patterns following resection of IPMNs: Metachronous multifocal occurrence of IPMNs, and distinct pancreatic ductal adenocarcinoma (PDAC) in the remnant pancreas. Several recent studies investigated the development of distinct PDAC during follow-up evaluation of IPMNs and the incidence rate ranged from 4.5 to 8%. Thus, IMPNs may be a good predictor for the early detection of PDAC during observation or after the resection of IPMNs. We herein report the rare case of a patient who underwent resection of PDAC that developed in the remnant pancreas 13 years after distal pancreatectomy with splenectomy for IPMNs. PDAC may develop in the remnant pancreas after pancreatectomy for IPMNs; thus, careful long-term follow-up with periodic surveillance, at least every 6 months, is warranted.

Laparoscopic total gastrectomy for advanced gastric cancer in a patient with situs inversus totalis

Situs inversus totalis (SIT) is a rare congenital anomaly. Generally, laparoscopic surgery is difficult to perform in patients with SIT because of both the potential challenges associated with unexpected vascular anomalies and the lack of standardized strategy for handling such cases. This is the first report of laparoscopic total gastrectomy with lymph node dissection for advanced gastric cancer in a patient with SIT. A 79-year-old man with SIT was diagnosed with advanced gastric cancer. We performed laparoscopic total gastrectomy with modified D2 lymph node dissection (D2 without splenectomy) and esophagojejunal anastomosis using an overlap method involving retrocolic Roux-en-Y reconstruction. The total operating time was 232 min, and blood loss was 110 mL. There were no postoperative complications. In summary, laparoscopic total gastrectomy for gastric cancer can be performed safely, even in a patient with SIT.

Low-Field Bi-Skyrmion Formation in a Noncentrosymmetric Chimney Ladder Ferromagnet

The real-space spin texture and the relevant magnetic parameters were investigated for an easy-axis noncentrosymmetric ferromagnet Cr_{11}Ge_{19} with Nowotny chimney ladder structure. Using Lorentz transmission electron microscopy, we report the formation of bi-Skyrmions, i.e., pairs of spin vortices with opposite magnetic helicities. The quantitative evaluation of the magnetocrystalline anisotropy and Dzyaloshinskii-Moriya interaction (DMI) proves that the magnetic dipolar interaction plays a more important role than the DMI on the observed bi-Skyrmion formation. Notably, the critical magnetic field value required for the formation of bi-Skyrmions turned out to be extremely small in this system, which is ascribed to strong easy-axis anisotropy associated with the characteristic helix crystal structure. The family of Nowotny chimney ladder compounds may offer a unique material platform where two distinctive Skyrmion formation mechanisms favoring different topological spin textures can become simultaneously active.

Effects of ionic liquids on the nanoscopic dynamics and phase behaviour of a phosphatidylcholine membrane

Ionic liquids (ILs) are potential candidates for new antimicrobials due to their tunable antibacterial and antifungal properties that are required to keep pace with the growing challenge of bacterial resistance. To a great extent their antimicrobial actions are related to the interactions of ILs with cell membranes. Here, we report the effects of ILs on the nanoscopic dynamics and phase behaviour of a dimyristoylphosphatidylcholine (DMPC) membrane, a model cell membrane, as studied using neutron scattering techniques. Two prototypical imidazolium-based ILs 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM[BF4]) and 1-decyl-3-methylimidazolium tetrafluoroborate (DMIM[BF4]), which differ only in terms of the alkyl chain length of cations, have been used for the present study. Fixed Elastic Window Scan (FEWS) shows that the incorporation of ILs affects the phase behaviour of the phospholipid membrane significantly and the transition from a solid gel to a fluid phase shifts to lower temperature. This is found to be consistent with our differential scanning calorimetry measurements. DMIM[BF4], which has a longer alkyl chain cation, affects the phase behaviour more strongly in comparison to BMIM[BF4]. The pressure-area isotherms of the DMPC monolayer measured at the air-water interface show that in the presence of ILs, isotherms shift towards higher area-per lipid molecule. DMIM[BF4] is found to shift the isotherm to a greater extent compared to BMIM[BF4]. Quasielastic neutron scattering (QENS) data show that both ILs act as a plasticizer, which enhances the fluidity of the membrane. DMIM[BF4] is found to be a stronger plasticizing agent in comparison to BMIM[BF4] that has a cation with a shorter alkyl chain. The incorporation of DMIM[BF4] enhances not only the long range lateral motion but also the localised internal motion of the lipids. On the other hand, BMIM[BF4] acts weakly in comparison to DMIM[BF4] and mainly alters the localised internal motion of the lipids. Any subtle change in the dynamical properties of the membrane can profoundly affect the stability of the cell. Hence, the dominant effect of the IL with the longer chain length on the dynamics of the phospholipid membrane might be correlated with its cytotoxic activity. QENS data analysis has provided a quantitative description of the effects of the two imidazolium-based ILs on the dynamical and phase behaviour of the model cell membrane, which is essential for a detailed understanding of their action mechanism.