Association between volume of patients undergoing stroke rehabilitation at acute care hospitals and improvement in activities of daily living

BACKGROUND

This study aimed to determine the relationship between the annual volume of patients undergoing rehabilitation per hospital and the outcomes of patients admitted for acute stroke.

METHODS

This observational study used nationwide administrative data. Data on stroke patients aged ≥ 20 years who underwent rehabilitation were extracted from 1,182 acute care hospitals in Japan. The exclusion criteria were extended hospital stay exceeding 180 days and death during hospitalization. Hospital volumes were divided into four quartiles of total patients per hospital. The primary outcome was an improvement in activities of daily living from admission to discharge measured using the Barthel index. Poisson regression analysis of activities of daily living improvement was performed using inverse probability of treatment weighting.

RESULTS

High rehabilitation volume was significantly correlated with improvements in activities of daily living using the "very low group" as a reference (risk ratio [95% confidence interval]): 1.06 [1.05-1.08], P<0.001). Low volume was also significantly associated with activities of daily living improvement (risk ratio [95% confidence interval]: 1.04 [1.03-1.06], P<0.001).

CONCLUSIONS

The annual volume of stroke patients undergoing multidisciplinary rehabilitation at a specific hospital may be a factor in the degree of patient improvement in activities of daily living.

Existing Data Sources for Clinical Epidemiology: Database of the National Hospital Organization in Japan

This review introduces the National Hospital Organization (NHO) database in Japan. The NHO has maintained two databases through a system of data collection from 140 hospitals in the NHO. National Hospital Organization Clinical Data Archives (NCDA) is collecting clinical information in real time from the electronic medical records since January 2016, and Medical Information Analysis (MIA) databank is collecting daily insurance claims data since April 2010. The NHO database covers more than 8 million patients in 140 hospitals throughout Japan. The database consists of the information of patient profiles, hospital admission and discharge, diagnosis with ICD-10 codes, text data from medical chart, daily health insurance claims such as medical procedures, medications or surgeries, vital signs and laboratory data, and so on. The NHO database includes a wide variety of diseases and settings, including acute, chronic and intractable diseases, emergency medical services, disaster medicine, response to emerging infectious disease outbreaks, medical care according to health policies such as psychiatry, tuberculosis, or muscular dystrophy, and health systems in sparsely populated non-urban areas. Among several common diseases, the database has representativeness in terms of age distribution compared with the Patient Survey 2017 by the Ministry of Health, Labour and Welfare. Interested researchers can contact (700-dbproject@mail.hosp.go.jp) the NHO database division to obtain more information about the NHO database for utilization.

Implementation of Rehabilitation and Patient Outcomes During the Initial COVID-19 Pandemic

Objectives:

This study investigated the impact of the initial outbreak of coronavirus disease (COVID-19) on rehabilitation and functional outcomes of patients in Japanese hospitals.

Methods:

The study subjects were hospitals belonging to Japan’s National Hospital Organization that provided inpatient care for patients with coronavirus COVID-19 during March–May 2020. We specifically focused on patients who were hospitalized for acute diseases, such as stroke, hip fracture, acute myocardial infarction, congestive heart failure, or chronic obstructive pulmonary disease, and received rehabilitation during hospitalization. Data were sourced from Japanese administrative data. The primary outcome was rehabilitation provision time in the target hospitals. The secondary outcomes were patient outcomes: rehabilitation participation time, length of hospital stay, 30-day readmission rate, and improvement of activities of daily living. Interrupted time series analysis was performed to evaluate the trend of rehabilitation provision time. Patient outcomes were compared with those for 2019.

Results:

The rehabilitation provision time for outpatients declined by 62% during the pandemic, while that for inpatients declined temporarily, and then increased. Compared with 2019 outcomes, rehabilitation participation time was longer and hospital stay length was shorter for stroke and hip-fracture patients, the 30-day readmission rate was increased for hip-fracture patients, and improvement of activities in daily living was less for patients with congestive heart failure who were totally dependent at admission. Other outcomes did not change.

Conclusions:

The findings suggest that during the initial COVID-19 pandemic, resources for rehabilitation were quickly reallocated to inpatient care, and the impact on inpatient outcomes was minimized.

Trends in the Use of Cardiac Rehabilitation in Japan Between 2010 and 2017 - An Epidemiological Survey

Background: Despite the prognostic effectiveness of cardiac rehabilitation (CR) in patients with cardiovascular disease (CVD), it has been underutilized. Understanding the trend of dissemination of CR over the years would help provide a perspective of CR in Japan. Methods and Results: A retrospective epidemiological survey between fiscal years 2010 and 2017 was conducted using the diagnosis procedure combination database (a Japanese administrative database). Data on 2,046,302 patients with CVD from 1,632 hospitals were extracted. The proportion of CR-certified hospitals among hospitals treating patients with CVD increased from 31.6% in 2010 to 56.6% in 2017. Over the same period, the participation rate in inpatient CR (ICR) increased from 18.3% to 39.0%, but the participation rate in outpatient CR (OCR) remained low (from 1.4% to 2.5%). The CR participation rates varied widely according to the main disease group. Approximately 95% of ICR participants did not continue CR after discharge. Conclusions: The number of CR-certified hospitals increased from 2010 to 2017, leading to increased ICR participation across patients with CVD; however, OCR has remained extremely underutilized. Immediate action is urgently required to increase the use of OCR.

Topological Kagome Magnet Co3Sn2S2 Thin Flakes with High Electron Mobility and Large Anomalous Hall Effect

Magnetic Weyl semimetals attract considerable interest not only for their topological quantum phenomena but also as an emerging materials class for realizing quantum anomalous Hall effect in the two-dimensional limit. A shandite compound Co₃Sn₂S₂ with layered kagome-lattices is one such material, where vigorous efforts have been devoted to synthesize the two-dimensional crystal. Here, we report a synthesis of Co₃Sn₂S₂ thin flakes with a thickness of 250 nm by chemical vapor transport method. We find that this facile bottom-up approach allows the formation of large-sized Co₃Sn₂S₂ thin flakes of high-quality, where we identify the largest electron mobility (∼2600 cm² V^-1 s^-1) among magnetic topological semimetals, as well as the large anomalous Hall conductivity (∼1400 Ω^-1 cm^-1) and anomalous Hall angle (∼32%) arising from the Berry curvature. Our study provides a viable platform for studying high-quality thin flakes of magnetic Weyl semimetal and stimulate further research on unexplored topological phenomena in the two-dimensional limit.

In-hospital cardiac rehabilitation and clinical outcomes in patients with acute myocardial infarction after percutaneous coronary intervention: a retrospective cohort study

OBJECTIVES

To verify the associations between participation in an in-hospital cardiac rehabilitation (CR) programme and clinical outcomes among patients with acute myocardial infarction (AMI) after percutaneous coronary intervention (PCI).

DESIGN

A retrospective cohort study using the Japanese administrative claims database.

SETTING

Japanese acute-care hospitals.

PARTICIPANTS

Patients aged ≥18 years who underwent PCI due to AMI and survived to discharge.

PRIMARY AND SECONDARY OUTCOME MEASURE

The primary outcomes were revascularisation, all-cause readmission and cardiac readmission (median follow-up period: 324 days, 236 days and 263 days, respectively). The secondary outcomes were all-cause mortality and cardiac mortality (median follow-up period: both were 460 days).

RESULT

The data of 13 697 patients were extracted from the database, and 65.4% of them participated in an in-hospital CR. The risks of revascularisation, all-cause readmission and cardiac readmission among CR participants were compared with those of non-participants using two statistical techniques: matched-pair analysis based on propensity score and a 30-day landmark analysis. The results of those analysis were consistent and showed that the CR participants had lower risk of revascularisation (adjusted HR: 0.74; 95% CI: 0.65 to 0.84), all-cause readmission (HR: 0.81; 95% CI: 0.74 to 0.88) and cardiac readmission (HR: 0.77; 95% CI: 0.70 to 0.85). However, all-cause mortality and cardiac mortality were not associated with participation in the CR.

CONCLUSIONS

It was suggested that in-hospital CR participation may reduce the risk of revascularisation, all-cause readmission and cardiac readmission among patients with AMI after PCI. In-hospital CR may expand the potential benefits of CR in addition to outpatient CR.

Direct Observation of the Statics and Dynamics of Emergent Magnetic Monopoles in a Chiral Magnet

In the three-dimensional (3D) Heisenberg model, topological point defects known as spin hedgehogs behave as emergent magnetic monopoles, i.e., quantized sources and sinks of gauge fields that couple strongly to conduction electrons, and cause unconventional transport responses such as the gigantic Hall effect. We observe a dramatic change in the Hall effect upon the transformation of a spin hedgehog crystal in a chiral magnet MnGe through combined measurements of magnetotransport and small-angle neutron scattering (SANS). At low temperatures, well-defined SANS peaks and a negative Hall signal are each consistent with expectations for a static hedgehog lattice. In contrast, a positive Hall signal takes over when the hedgehog lattice fluctuates at higher temperatures, with a diffuse SANS signal observed upon decomposition of the hedgehog lattice. Our approach provides a simple way to both distinguish and disentangle the roles of static and dynamic emergent monopoles on the augmented Hall motion of conduction electrons.

Giant magneto-optical responses in magnetic Weyl semimetal Co3Sn2S2

The Weyl semimetal (WSM), which hosts pairs of Weyl points and accompanying Berry curvature in momentum space near Fermi level, is expected to exhibit novel electromagnetic phenomena. Although the large optical/electronic responses such as nonlinear optical effects and intrinsic anomalous Hall effect (AHE) have recently been demonstrated indeed, the conclusive evidence for their topological origins has remained elusive. Here, we report the gigantic magneto-optical (MO) response arising from the topological electronic structure with intense Berry curvature in magnetic WSM Co₃Sn₂S₂. The low-energy MO spectroscopy and the first-principles calculation reveal that the interband transitions on the nodal rings connected to the Weyl points show the resonance of the optical Hall conductivity and give rise to the giant intrinsic AHE in dc limit. The terahertz Faraday and infrared Kerr rotations are found to be remarkably enhanced by these resonances with topological electronic structures, demonstrating the novel low-energy optical response inherent to the magnetic WSM.

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.

Myositis with sarcoplasmic inclusions in Nakajo-Nishimura syndrome: a genetic inflammatory myopathy

AIMS

Nakajo-Nishimura syndrome (NNS) is an autosomal recessive disease caused by biallelic mutations in the PSMB8 gene that encodes the immunoproteasome subunit β5i. There have been only a limited number of reports on the clinicopathological features of the disease in genetically confirmed cases.

METHODS

We studied clinical and pathological features of three NNS patients who all carry the homozygous p.G201V mutations in PSMB8. Patients' muscle specimens were analysed with histology and immunohistochemistry.

RESULTS

All patients had episodes of typical periodic fever and skin rash, and later developed progressive muscle weakness and atrophy, similar to previous reports. Oral corticosteroid was used for treatment but showed no obvious efficacy. On muscle pathology, lymphocytes were present in the endomysium surrounding non-necrotic fibres, as well as in the perimysium perivascular area. Nearly all fibres strongly expressed MHC-I in the sarcolemma. In the eldest patient, there were abnormal protein aggregates in the sarcoplasm, immunoreactive to p62, TDP-43 and ubiquitin antibodies.

CONCLUSIONS

These results suggest that inflammation, inclusion pathology and aggregation of abnormal proteins underlie the progressive clinical course of the NNS pathomechanism.

Predictors Associated with Survival Among Elderly In-Patients Who Receive Cardiopulmonary Resuscitation in Japan: An Observational Cohort Study

BACKGROUND

Little is known about the outcomes of in-hospital cardiopulmonary resuscitation (CPR) in Asian populations including elderly patients in Japan.

OBJECTIVE

To determine the survival outcome of in-hospital CPR among elderly patients in Japan, and to identify predictors associated with survival.

DESIGN

Retrospective cohort study in 81 Japanese hospitals from April 1, 2010 to March 31, 2016.

PATIENTS

We included elderly patients (age ≥ 65 years) who received CPR after 2 days of hospitalization.

MAIN MEASURES

The primary outcome was survival at hospital discharge and the secondary outcomes were the discharge disposition and consciousness level of patients who survived to hospital discharge. To determine predictors associated with survival after in-hospital CPR, we fit multivariable models for patient-level and institutional-level factors.

KEY RESULTS

Among the 5365 patients who received CPR, 595 (11%) survived to discharge. Of those who survived to discharge, 46% of patients were discharged home, and 10% of patients were comatose at discharge. Older age and higher burden of comorbidities were associated with reduced survival. The adjusted OR was 0.35 (95% CI, 0.22-0.55) for age ≥ 90 years compared to age 65-69 years, and 0.68 (95% CI, 0.48-0.97) for Charlson Comorbidity Index score of ≥ 4 compared with score of 0. Other predictors of reduced survival included receiving CPR on weekends compared to weekdays (AOR, 0.63; 95% CI, 0.51-0.77) and in small hospitals compared to large hospitals (AOR, 0.58; 95% CI, 0.40-0.83).

CONCLUSIONS

Among elderly patients in Japan, the survival rate of in-hospital CPR was approximately one in ten, and less than half of these patients were discharged home. In addition to older age and higher illness burden, receiving CPR on weekends and/or in small hospitals were significant predictors of reduced survival. These findings should be considered in advanced care planning discussions with elderly patients to avoid subjecting patients to CPR that are likely futile.

Trends in descriptions of palliative care in the cancer clinical practice guidelines before and after enactment of the Cancer Control Act (2007): content analysis

BACKGROUND

Palliative care was a priority issue in the Cancer Control Act enacted in 2007 in Japan, and this has resulted in efforts being made toward educational goals in clinical settings. An investigation of how descriptions of palliative care for the treatment of cancer have changed in clinical practice guidelines (CPGs) could be expected to provide a better understanding of palliative care-related decision-making. This study aimed to identify trends in descriptions of palliative care in cancer CPGs in Japan before and after enactment of the Cancer Control Act.

METHODS

Content analysis was used to count the lines in all relevant CPGs. We then compared the number of lines and the proportion of descriptions mentioning palliative care at two time points: the first survey (selection period: February to June 2007) and the second survey (selection period: February to December 2015). Descriptions from the CPGs were independently selected from the Toho University Medical Media Center and Medical Information Network Distribution Service databases, and subsequently reviewed, by two investigators.

RESULTS

Descriptions were analyzed for 10 types of cancer. The proportion of descriptions in the first survey (4.4%; 933/21,344 lines) was similar to that in the second survey (4.5%; 1325/29,269 lines).

CONCLUSIONS

After the enactment of the Cancer Control Act, an increase was observed in the number, but not in the proportion, of palliative care descriptions in Japanese cancer CPGs. In the future, CPGs can be expected to play a major role in helping cancer patients to incorporate palliative care more smoothly.

Electrical magnetochiral effect induced by chiral spin fluctuations

Chirality of matter can produce unique responses in optics, electricity and magnetism. In particular, magnetic crystals transmit their handedness to the magnetism via antisymmetric exchange interaction of relativistic origin, producing helical spin orders as well as their fluctuations. Here we report for a chiral magnet MnSi that chiral spin fluctuations manifest themselves in the electrical magnetochiral effect, i.e. the nonreciprocal and nonlinear response characterized by the electrical resistance depending on inner product of current and magnetic field. Prominent electrical magnetochiral signals emerge at specific temperature-magnetic field-pressure regions: in the paramagnetic phase just above the helical ordering temperature and in the partially-ordered topological spin state at low temperatures and high pressures, where thermal and quantum spin fluctuations are conspicuous in proximity of classical and quantum phase transitions, respectively. The finding of the asymmetric electron scattering by chiral spin fluctuations may explore new electromagnetic functionality in chiral magnets.

The magnetism-induced chirality in electron transportation is of fundamental importantance in condensed matter physics but the origin is still unclear. Here the authors demonstrate that the asymmetric electron scattering by chiral spin fluctuations can be the key to the electrical magnetochiral effect in MnSi.

Underuse of Cardiac Rehabilitation in Workers With Coronary Artery Disease - Claims Database Survey in Japan

BACKGROUND

Workers with coronary artery disease (CAD) require evidence-based care in order to return to work safely. We assessed the use of cardiac rehabilitation (CR) among workers with CAD, and identified the factors associated with CR use.Methods and Results:A retrospective cohort study based on data from a health insurance claims database was conducted. We identified workers aged ≥18 years who underwent percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) between 2006 and 2013, and reviewed the utilization of inpatient or outpatient CR. Logistic regression was used to identify the factors associated with CR use. A total of 1,699 patients were included. The frequency of inpatient and outpatient CR use was 23.7% (n=402) and 4.2% (n=72), respectively. Patients diagnosed with ST-elevated myocardial infarction were most likely to receive inpatient CR, and patients undergoing CABG were more likely to receive inpatient CR than those undergoing PCI. Moreover, inpatient CR use was associated with longer hospitalization duration, catecholamine use, and no history of chronic kidney disease. Furthermore, both unstable and stable angina were negatively correlated with outpatient CR use.

CONCLUSIONS

Most of the Japanese workers with CAD in this study did not undergo CR. The type of CAD was strongly associated with inpatient and outpatient CR use. Thus, a strong evidence-practice gap exists in secondary preventative care within this group of patients.

Temperature and Magnetic Field Dependence of the Internal and Lattice Structures of Skyrmions by Off-Axis Electron Holography

The internal and lattice structures of magnetic Skyrmions in B20-type FeGe are investigated using off-axis electron holography. The temperature, magnetic field, and angular dependence of the magnetic moments of individual Skyrmions are analyzed. The internal Skyrmion shape is found to vary with applied magnetic field. In contrast, the inter-Skyrmion distance remains almost unchanged in the lattice phase over the studied range of applied field. The amplitude of the local magnetic moment is found to vary with temperature, while the Skyrmion shape does not change significantly. Deviations from a circular to a hexagonal Skyrmion structure are observed in the lattice phase, in agreement with the results of micromagnetic simulations.

Proposal of quality indicators for cardiac rehabilitation after acute coronary syndrome in Japan: a modified Delphi method and practice test

OBJECTIVES

Cardiac rehabilitation is underused and its quality in practice is unclear. A quality indicator is a measurable element of clinical practice performance. This study aimed to propose a set of quality indicators for cardiac rehabilitation following an acute coronary event in the Japanese population and conduct a small-size practice test to confirm feasibility and applicability of the indicators in real-world clinical practice.

DESIGN AND SETTING

This study used a modified Delphi technique (the RAND/UCLA appropriateness method), a consensus method which involves an evidence review, a face-to-face multidisciplinary panel meeting and repeated anonymous rating. Evidence to be reviewed included clinical practice guidelines available in English or Japanese and existing quality indicators. Performance of each indicator was assessed retrospectively using medical records at a university hospital in Japan.

PARTICIPANTS

10 professionals in cardiac rehabilitation for the consensus panel.

RESULTS

In the literature review, 23 clinical practice guidelines and 16 existing indicators were identified to generate potential indicators. Through the consensus-building process, a total of 30 indicators were assessed and finally 13 indicators were accepted. The practice test (n=39) revealed that 74% of patients underwent cardiac rehabilitation. Median performance of process measures was 93% (IQR 46-100%). 'Communication with the doctor who referred the patient to cardiac rehabilitation' and 'continuous participation in cardiac rehabilitation' had low performance (32% and 38%, respectively).

CONCLUSIONS

A modified Delphi technique identified a comprehensive set of quality indicators for cardiac rehabilitation. The single-site, small-size practice test confirmed that most of the proposed indicators were measurable in real-world clinical practice. However, some clinical processes which are not covered by national health insurance in Japan had low performance. Further studies will be needed to clarify and improve the quality of care in cardiac rehabilitation.

Local dynamics of topological magnetic defects in the itinerant helimagnet FeGe

Chiral magnetic interactions induce complex spin textures including helical and conical spin spirals, as well as particle-like objects such as magnetic skyrmions and merons. These spin textures are the basis for innovative device paradigms and give rise to exotic topological phenomena, thus being of interest for both applied and fundamental sciences. Present key questions address the dynamics of the spin system and emergent topological defects. Here we analyse the micromagnetic dynamics in the helimagnetic phase of FeGe. By combining magnetic force microscopy, single-spin magnetometry and Landau–Lifschitz–Gilbert simulations we show that the nanoscale dynamics are governed by the depinning and subsequent motion of magnetic edge dislocations. The motion of these topologically stable objects triggers perturbations that can propagate over mesoscopic length scales. The observation of stochastic instabilities in the micromagnetic structure provides insight to the spatio-temporal dynamics of itinerant helimagnets and topological defects, and discloses open challenges regarding their technological usage.

Topological defects may strongly influence the evolution of a materials' micromagnetic structure whilst their manipulation forms the basis for emerging technological concepts. Here, the authors study the depinning and motion of magnetic edge dislocations in the domain structure of helimagnetic FeGe.

Critical phenomena of emergent magnetic monopoles in a chiral magnet

Second-order continuous phase transitions are characterized by symmetry breaking with order parameters. Topological orders of electrons, characterized by the topological index defined in momentum space, provide a distinct perspective for phase transitions, which are categorized as quantum phase transitions not being accompanied by symmetry breaking. However, there are still limited observations of counterparts in real space. Here we show a real-space topological phase transition in a chiral magnet MnGe, hosting a periodic array of hedgehog and antihedgehog topological spin singularities. This transition is driven by the pair annihilation of the hedgehogs and antihedgehogs acting as monopoles and antimonopoles of the emergent electromagnetic field. Observed anomalies in the magnetoresistivity and phonon softening are consistent with the theoretical prediction of critical phenomena associated with enhanced fluctuations of emergent field near the transition. This finding reveals a vital role of topology of the spins in strongly correlated systems.

Phase transitions in topologically non-trivial systems are characterized by changes of topological invariants, rather than conventional order parameters. Here, the authors propose a real-space topological phase transition upon pair annihilation of emergent monopoles inherent in chiral magnet MnGe.

5-hydroxytryptamine and Lyme disease. Opportunity for a novel therapy to reduce the cerebellar tremor?

Lyme boreliosis is caused by the spirochete Borrelia burdorferi, which is transmitted by ticks. A 59 year-old woman developed pyrexia, strong headaches, ataxia, dysarthria and tremor of the limbs after a tick bite. She was unable to work and eat on her own. She was hospitalized three times and diagnosed with cerebellar intention tremor, cerebellar ataxia, dysarthria, bilateral horizontal gaze paralysis and a central lesion of the left facial nerve. There were no pyramidal, sensory or psychiatric disturbances. The brain MRI showed multifocal leucoencephalopathy with many hyperintense areas in both hemispheres, as well as in the left superior pedunculus cerebellaris. Diagnosis was confirmed by serologic examination. Treatment with cephtriaxone, doxycycline, methylprednisolone, cephixime and ciprofloxacine was administered without effect on the tremor, ataxia and horizontal gaze paralysis. Treatment was then administered with 5-hydroxytriptamine (5-HT) in increased doses. The result of the three-month treatment with 5-HT was a gradual diminution of the tremor and the ataxia and an increase in the ability to eat, walk and work independently.

Interstitial granulomatous dermatitis demonstrating small, discrete skin-colored papules

We report the case of a 67-year-old female with a rare variant of interstitial granulomatous dermatitis showing multiple skin-colored papules. Clinically, numerous skin-colored or reddish papules were distributed on her back and posterior thighs with itchy scaly erythema on the upper back. After topical steroid application, skin-colored papules still remained after the disappearance of itchy scaly erythema. Histopathologically, perivascular and interstitial infiltration of lymphocytes and histiocytes with occasional multinucleated giant cells were observed in the superficial and mid reticular dermis, accompanied by mild mucin deposition. Interstitial granulomatous dermatitis is similar to interstitial granuloma annulare, but can be differentiated from it by lesser degrees of collagen degeneration with mucin deposition and frequent association with arthritis or rheumatic diseases. As previously reported, multiple asymptomatic skin-colored papules are considered a rare but distinct variant of interstitial granulomatous dermatitis. Although no apparent underlying disorder has developed in the presented case, careful follow-up needs to be continued.

Large anisotropic deformation of skyrmions in strained crystal

Mechanical control of magnetism is an important and promising approach in spintronics. To date, strain control has mostly been demonstrated in ferromagnetic structures by exploiting a change in magnetocrystalline anisotropy. It would be desirable to achieve large strain effects on magnetic nanostructures. Here, using in situ Lorentz transmission electron microscopy, we demonstrate that anisotropic strain as small as 0.3% in a chiral magnet of FeGe induces very large deformations in magnetic skyrmions, as well as distortions of the skyrmion crystal lattice on the order of 20%. Skyrmions are stabilized by the Dzyaloshinskii-Moriya interaction, originating from a chiral crystal structure. Our results show that the change in the modulation of the strength of this interaction is amplified by two orders of magnitude with respect to changes in the crystal lattice due to an applied strain. Our findings may provide a mechanism to achieve strain control of topological magnetic structures based on the Dzyaloshinskii-Moriya interaction.

The "mystery" of cutaneous sarcoidosis: facts and controversies

The reason why the cutaneous form of sarcoidosis is well known in the literature is because of its spectrum of manifestations granting it the fame of a Great Imitator. The mystery shrouding the pathogenesis of this rare cutaneous disease is still there (in spite of the fundamental progress of the various diagnostic methods in current day medicine). The production of the morphological substrate - the epithelioid cell granuloma - which is considered to be characteristic of skin sarcoidosis, could, however, also be the end result of a reaction to i) various specific infectious agents such as Leishmaniasis cutis, coccidioidomycosis, etc., ii) certain residual bacterial or other mycobacterial antigens which, at the moment of setting the diagnosis are - by definition - non-infectious but still immunogenic, as well as iii) different tumor antigens in lesional tissue or other location. Often, differentiating between sarcodiosis and a sarcoid-like reaction, based on the updated criteria for cutaneous sarcoidosis, is problematic to downright impossible. A future characterization of the genetic signature of the two conditions, as well as the implementation of additional mandatory panels for i) the identification of certain infectious or ii) non-infectious but immunogenic and iii) tumor antigens in the epithelioid cell granuloma (or in another location in the organism), could be a considerable contribution to the process of differentiating between the two above-mentioned conditions. This will create conditions for greater accuracy when setting the subsequent therapeutic approaches.

Thermally driven ratchet motion of a skyrmion microcrystal and topological magnon Hall effect

Spontaneously emergent chirality is an issue of fundamental importance across the natural sciences. It has been argued that a unidirectional (chiral) rotation of a mechanical ratchet is forbidden in thermal equilibrium, but becomes possible in systems out of equilibrium. Here we report our finding that a topologically nontrivial spin texture known as a skyrmion--a particle-like object in which spins point in all directions to wrap a sphere--constitutes such a ratchet. By means of Lorentz transmission electron microscopy we show that micrometre-sized crystals of skyrmions in thin films of Cu2OSeO3 and MnSi exhibit a unidirectional rotation motion. Our numerical simulations based on a stochastic Landau-Lifshitz-Gilbert equation suggest that this rotation is driven solely by thermal fluctuations in the presence of a temperature gradient, whereas in thermal equilibrium it is forbidden by the Bohr-van Leeuwen theorem. We show that the rotational flow of magnons driven by the effective magnetic field of skyrmions gives rise to the skyrmion rotation, therefore suggesting that magnons can be used to control the motion of these spin textures.

Towards control of the size and helicity of skyrmions in helimagnetic alloys by spin-orbit coupling

Chirality--that is, left- or right-handedness--is an important concept in a broad range of scientific areas. In condensed matter, chirality is found not only in molecular or crystal forms, but also in magnetic structures. A magnetic skyrmion is a topologically stable spin vortex structure, as observed in chiral-lattice helimagnets, and is one example of such a structure. The spin swirling direction (skyrmion helicity) should be closely related to the underlying lattice chirality via the relativistic spin-orbit coupling. Here, we report on the correlation between skyrmion helicity and crystal chirality in alloys of helimagnets Mn(1-x)Fe(x)Ge with varying compositions by Lorentz transmission electron microscopy and convergent-beam electron diffraction over a broad range of compositions (x = 0.3-1.0). The skyrmion lattice constant shows non-monotonous variation with composition x, with a divergent behaviour around x = 0.8, where the correlation between magnetic helicity and crystal chirality changes sign. This originates from continuous variation of the spin-orbit coupling strength and its sign reversal in the metallic alloys as a function of x. Controllable spin-orbit coupling may offer a promising way to tune skyrmion size and helicity.

Robust formation of Skyrmions and topological Hall effect anomaly in epitaxial thin films of MnSi

Magnetotransport properties have been investigated for epitaxial thin films of B20-type MnSi grown on Si(111) substrates. Lorentz transmission electron microscopy images clearly point to the robust formation of Skyrmions over a wide temperature-magnetic field region. New features distinct from those reported previously for MnSi are observed for epitaxial films: a shorter (nearly half) period of the spin helix and Skyrmions, and a topological Hall effect anomaly consisting in ∼2.2 times enhancement of the amplitude and in the opposite sign with respect to bulk samples.

Large topological Hall effect in a short-period helimagnet MnGe

We have observed an unconventional, likely topological, Hall effect over a wide temperature region in the magnetization process of a chiral-lattice helimagnet MnGe. The magnitude of the topological Hall resistivity is nearly temperature-independent below 70 K, which reflects the real-space fictitious magnetic field proportional to a geometric quantity (scalar spin chirality) of the underlying spin texture. From the neutron diffraction study, it is anticipated that a relatively short-period (3-6 nm) noncoplanar spin structure is stabilized from the proper screw state in a magnetic field to produce the largest topological Hall response among the B20-type (FeSi-type) chiral magnets.

Near room-temperature formation of a skyrmion crystal in thin-films of the helimagnet FeGe

The skyrmion, a vortex-like spin-swirling object, is anticipated to play a vital role in quantum magneto-transport processes such as the quantum Hall and topological Hall effects. The existence of the magnetic skyrmion crystal (SkX) state was recently verified experimentally for MnSi and Fe(0.5)Co(0.5)Si by means of small-angle neutron scattering and Lorentz transmission electron microscopy. However, to enable the application of such a SkX for spintronic function, materials problems such as a low crystallization temperature and low stability of SkX have to be overcome. Here we report the formation of SkX close to room temperature in thin-films of the helimagnet FeGe. In addition to the magnetic twin structure, we found a magnetic chirality inversion of the SkX across lattice twin boundaries. Furthermore, for thin crystal plates with thicknesses much smaller than the SkX lattice constant (as) the two-dimensional SkX is quite stable over a wide range of temperatures and magnetic fields, whereas for quasi-three-dimensional films with thicknesses over as the SkX is relatively unstable and observed only around the helical transition temperature. The room-temperature stable SkX state as promised by this study will pave a new path to designing quantum-effect devices based on the controllable skyrmion dynamics.

Expression of prostate-specific antigen and androgen receptor in extramammary Paget's disease and carcinoma

Prostate-specific antigen (PSA) is a kallikrein-like serine proteinase (human kallikrein 3) produced by epithelial cells of both benign and malignant prostate tissue. In this study, PSA expression was histologically examined in tissue specimens from 34 patients with extramammary Paget's disease (EPD; 31 cases) and extramammary Paget's carcinoma (EPC; three cases), but no associated prostate carcinoma. Tumour cells positive for PSA were found in 17 of the 34 cases. Based on this finding, we examined serum PSA level in the three EPC cases. A high level of serum PSA was observed in one case of EPC, which was correlated with disease progression. Because some reports suggest that 50-80% cases of EPD/EPC express androgen receptor (AR), we also examined expression of AR. Immunohistological staining showed correlation of PSA and AR in expression. These results suggest that PSA and the androgen signalling pathway may be involved in the pathogenesis of EPD.

Expressional screening of interferon-stimulated genes for antiviral activity against hepatitis C virus replication

Type-I interferons (IFNs) and the interferon-stimulated genes (ISGs) play a major role in antivirus responses against hepatitis C virus (HCV) infection. In this study, we studied expression profiles of ISGs in cells supporting subgenomic HCV replication (Huh7/Rep), and screened their activities to suppress HCV replication. Real-time PCR analyses showed that the expression levels of 23 ISGs were significantly lower in Huh7/Rep than naive Huh7 cells due to transcriptional suppression of the interferon-stimulated response element (ISRE). Furthermore, the expression level of ISGs was also decreased in the cured Huh7 cells in which replicon had been eliminated (cHuh7), indicating adaptation of the cells to support HCV replication by downregulating ISGs. On the other hand, expression of HCV replicon was significantly suppressed by overexpression of several ISGs including PKR, MxA, IRF-9, GBP-1, IFI-6-16, IFI-27, 25OAS and IRF-1. Knock down of GBP-1, IFI-6-16 and IFI-27 by short hairpin RNA resulted in increase of HCV replication. Thus, we conclude that downregulation of ISG expression is required in the host cells supporting HCV replication and that several ISGs directly suppress HCV replication. The search for ISGs that regulate HCV replication may help to elucidate the cellular antiviral defence mechanisms against HCV infection.

Site-specific mutation of the interferon sensitivity-determining region (ISDR) modulates hepatitis C virus replication

The number of amino acid substitutions in the interferon sensitivity-determining region (ISDR) in the nonstructural 5A (NS5A) gene of hepatitis C virus (HCV) is closely associated with the interferon (IFN) response and viral load. Several HCV replicon-based studies have reported that ISDR sequences had an influence on viral replication in vitro. However, it is unclear as to how different ISDR sequences affect HCV replication. Various clinically observed ISDR sequences were introduced into HCV replicons and their contribution to viral replication was investigated using a colony formation assay and/or a transient replication assay. A mapping study of the ISDR was performed to identify the amino acid positions that critically affect replication. While no colonies were formed in the colony formation assay using HCV replicons with few mutations (0, 1 and 3) in the ISDR, numerous colonies (>200) appeared when using constructs with six mutations. Introduction of various distinct ISDR sequences with multiple mutations resulted in replication enhancement in transient assays. A mapping study identified several specific sites in the ISDR that critically affected replication, including codon 2209 which, in patients, was closely associated with a strong response to IFN. ISDR sequences associated with a clinical IFN response and viral load modulated the replication of HCV replicons, suggesting the importance of the ISDR sequence in HCV infection.

Introduction of NS5A mutations enables subgenomic HCV replicon derived from chimpanzee-infectious HC-J4 isolate to replicate efficiently in Huh-7 cells

Hepatitis C virus (HCV) subgenomic replicon has been reported to replicate efficiently and continuously in human hepatoma Huh-7 cells. To extend the previous results to other isolated HCV clones, we constructed another HCV replicon from HC-J4, one of chimpanzee-infectious HCV clones. An HCV replicon derived from HC-J4 (RpJ4) consists of HCV-5' untranslated region, neomycin phosphotransferase gene, the encephalomyocarditis virus internal ribosomal entry site, HCV nonstructural region, NS3 to NS5B, and HCV-3' untranslated region. The adaptive mutations known to be required for HCV-Con1 replicon were introduced in RpJ4 replicon, aa.(amino acids number according to HC-J4) 2197 serine to proline, deletion of serine at aa.2201, and aa.2204 serine to isoleucine (RpJ4-S2197P, RpJ4-S22001del, and RpJ4-S2204I). RpJ4/ISDR mutant and RpJ4-S2201del/ISDR mutant were also constructed by introducing six amino acid mutations into the interferon sensitivity determining region (ISDR). After transfection into Huh-7 cells and G418 selection, RpJ4 and RpJ4/ISDR mutants did not produce any colony. In contrast, G418-resistant cells were transduced efficiently by RpJ4-S2197P, RpJ4-S2204I, RpJ4-S2201del and RpJ4-S2201del/ISDR mutant, with the RpJ4-S2201del/ISDR mutant being most efficient. Hence the HCV replicon derived from HC-J4 can replicate efficiently following the introduction of adaptive mutations into the upstream region of ISDR. Moreover, additional introduction of mutations into ISDR further enhanced its replication. These findings demonstrate that the genetic structure of the NS5A domain is critical in HCV replications.