Evidence for a finite-momentum Cooper pair in tricolor d-wave superconducting superlattices

Fermionic superfluidity with a nontrivial Cooper-pairing, beyond the conventional Bardeen-Cooper-Schrieffer state, is a captivating field of study in quantum many-body systems. In particular, the search for superconducting states with finite-momentum pairs has long been a challenge, but establishing its existence has long suffered from the lack of an appropriate probe to reveal its momentum. Recently, it has been proposed that the nonreciprocal electron transport is the most powerful probe for the finite-momentum pairs, because it directly couples to the supercurrents. Here we reveal such a pairing state by the non-reciprocal transport on tricolor superlattices with strong spin-orbit coupling combined with broken inversion-symmetry consisting of atomically thin d-wave superconductor CeCoIn5. We find that while the second-harmonic resistance exhibits a distinct dip anomaly at the low-temperature (T)/high-magnetic field (H) corner in the HT-plane for H applied to the antinodal direction of the d-wave gap, such an anomaly is absent for H along the nodal direction. By carefully isolating extrinsic effects due to vortex dynamics, we reveal the presence of a non-reciprocal response originating from intrinsic superconducting properties characterized by finite-momentum pairs. We attribute the high-field state to the helical superconducting state, wherein the phase of the order parameter is spontaneously spatially modulated.

Effects of Preserving Anatomically Positioned and Adequate Remnant ACL Tissue in Double-Bundle ACL Reconstruction

Background

The advantages of remnant tissue preservation in anterior cruciate ligament (ACL) reconstruction (ACLR) remain controversial.

Hypothesis

It was hypothesized that a large amount of remnant tissue, especially if anatomically positioned, would improve patient-reported outcomes and second-look graft appearance after preserved double-bundle ACLR (DB-ACLR).

Study Design

Cohort study; Level of evidence, 3.

Methods

This retrospective study included 89 consecutive patients who underwent unilateral remnant-preserving DB-ACLR using 2 hamstring tendon autografts. The authors categorized the arthroscopic findings into 3 groups according to the location and volume of the ACL remnant tissue in the femoral notch: (1) anatomical attachment (group AA; n = 34); (2) nonanatomical attachment (group NA; n = 33); and (3) no remnant (group NR; n = 22). Based on second-look arthroscopy, the reconstructed graft was graded as excellent, fair, or poor. Patient-reported outcomes were evaluated at 2 years after surgery using the Knee injury and Osteoarthritis Outcome Score (KOOS) and the Japanese Anterior Cruciate Ligament Questionnaire-25 (JACL-25).

Results

The AA and NA groups had a significantly shorter time from injury to surgery compared with the NR group (P = .0165). Considering the second-look arthroscopic findings, the authors found a significant difference in synovial coverage of the grafts between the 3 groups (P = .0018). There were no significant differences in the overall KOOS and JACL-25 score among the 3 groups; however, the KOOS-Sport and Recreation and KOOS-Quality of Life subscale scores were significantly higher in the AA group compared with the NA and NR groups (P = .0014 and .0039, respectively). The JACL-25 score for middle- to high-speed flexion and extension was significantly better in the AA group versus the NR group (P = .0261).

Conclusion

This study showed that preserving anatomically positioned and adequate remnant tissue during DB-ACLR improved second-look graft appearance and KOOS-Sport and Recreation and KOOS-Quality of Life scores.

Quantifying the Size and Duration of a Microburst-Producing Chorus Region on 5 December 2017

Microbursts are impulsive (<1 s) injections of electrons into the atmosphere, thought to be caused by nonlinear scattering by chorus waves. Although attempts have been made to quantify their contribution to outer belt electron loss, the uncertainty in the overall size and duration of the microburst region is typically large, so that their contribution to outer belt loss is uncertain. We combine datasets that measure chorus waves (Van Allen Probes [RBSP], Arase, ground-based VLF stations) and microburst (>30 keV) precipitation (FIREBIRD II and AC6 CubeSats, POES) to determine the size of the microburst-producing chorus source region beginning on 5 December 2017. We estimate that the long-lasting (∼30 hr) microburst-producing chorus region extends from 4 to 8Δ MLT and 2-5Δ L. We conclude that microbursts likely represent a major loss source of outer radiation belt electrons for this event.

Collaborative Research Activities of the Arase and Van Allen Probes

This paper presents the highlights of joint observations of the inner magnetosphere by the Arase spacecraft, the Van Allen Probes spacecraft, and ground-based experiments integrated into spacecraft programs. The concurrent operation of the two missions in 2017-2019 facilitated the separation of the spatial and temporal structures of dynamic phenomena occurring in the inner magnetosphere. Because the orbital inclination angle of Arase is larger than that of Van Allen Probes, Arase collected observations at higher L -shells up to L ∼ 10 . After March 2017, similar variations in plasma and waves were detected by Van Allen Probes and Arase. We describe plasma wave observations at longitudinally separated locations in space and geomagnetically-conjugate locations in space and on the ground. The results of instrument intercalibrations between the two missions are also presented. Arase continued its normal operation after the scientific operation of Van Allen Probes completed in October 2019. The combined Van Allen Probes (2012-2019) and Arase (2017-present) observations will cover a full solar cycle. This will be the first comprehensive long-term observation of the inner magnetosphere and radiation belts.

Quasiparticle Nodal Plane in the Fulde-Ferrell-Larkin-Ovchinnikov State of FeSe

The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, characterized by Cooper pairs condensed at finite momentum, has been a long-sought state that remains unresolved in many classes of fermionic systems, including superconductors and ultracold atoms. A fascinating aspect of the FFLO state is the emergence of periodic nodal planes in real space, but its observation is still lacking. Here we investigate the superconducting order parameter at high magnetic fields H applied perpendicular to the ab plane in a high-purity single crystal of FeSe. The heat capacity and magnetic torque provide thermodynamic evidence for a distinct superconducting phase at the low-temperature/high-field corner of the phase diagram. Despite the bulk superconductivity, spectroscopic-imaging scanning tunneling microscopy performed on the same crystal demonstrates that the order parameter vanishes at the surface upon entering the high-field phase. These results provide the first demonstration of a pinned planar node perpendicular to H, which is consistent with a putative FFLO state.

Half-integer quantized anomalous thermal Hall effect in the Kitaev material candidate α-RuCl3

Half-integer thermal quantum Hall conductance has recently been reported for the two-dimensional honeycomb material α-RuCl₃ We found that the half-integer thermal Hall plateau appears even for a magnetic field with no out-of-plane components. The measured field-angular variation of the quantized thermal Hall conductance has the same sign structure as the topological Chern number of the pure Kitaev spin liquid. This observation suggests that the non-Abelian topological order associated with fractionalization of the local magnetic moments persists even in the presence of non-Kitaev interactions in α-RuCl₃.

Penetration of MeV electrons into the mesosphere accompanying pulsating aurorae

Pulsating aurorae (PsA) are caused by the intermittent precipitations of magnetospheric electrons (energies of a few keV to a few tens of keV) through wave-particle interactions, thereby depositing most of their energy at altitudes ~ 100 km. However, the maximum energy of precipitated electrons and its impacts on the atmosphere are unknown. Herein, we report unique observations by the European Incoherent Scatter (EISCAT) radar showing electron precipitations ranging from a few hundred keV to a few MeV during a PsA associated with a weak geomagnetic storm. Simultaneously, the Arase spacecraft has observed intense whistler-mode chorus waves at the conjugate location along magnetic field lines. A computer simulation based on the EISCAT observations shows immediate catalytic ozone depletion at the mesospheric altitudes. Since PsA occurs frequently, often in daily basis, and extends its impact over large MLT areas, we anticipate that the PsA possesses a significant forcing to the mesospheric ozone chemistry in high latitudes through high energy electron precipitations. Therefore, the generation of PsA results in the depletion of mesospheric ozone through high-energy electron precipitations caused by whistler-mode chorus waves, which are similar to the well-known effect due to solar energetic protons triggered by solar flares.

Oxygen torus and its coincidence with EMIC wave in the deep inner magnetosphere: Van Allen Probe B and Arase observations

We investigate the longitudinal structure of the oxygen torus in the inner magnetosphere for a specific event found on 12 September 2017, using simultaneous observations from the Van Allen Probe B and Arase satellites. It is found that Probe B observed a clear enhancement in the average plasma mass (M) up to 3-4 amu at L = 3.3-3.6 and magnetic local time (MLT) = 9.0 h. In the afternoon sector at MLT ~ 16.0 h, both Probe B and Arase found no clear enhancements in M. This result suggests that the oxygen torus does not extend over all MLT but is skewed toward the dawn. Since a similar result has been reported for another event of the oxygen torus in a previous study, a crescent-shaped torus or a pinched torus centered around dawn may be a general feature of the O+ density enhancement in the inner magnetosphere. We newly find that an electromagnetic ion cyclotron (EMIC) wave in the H+ band appeared coincidently with the oxygen torus. From the lower cutoff frequency of the EMIC wave, the ion composition of the oxygen torus is estimated to be 80.6% H+, 3.4% He+, and 16.0% O+. According to the linearized dispersion relation for EMIC waves, both He+ and O+ ions inhibit EMIC wave growth and the stabilizing effect is stronger for He+ than O+. Therefore, when the H+ fraction or M is constant, the denser O+ ions are naturally accompanied by the more tenuous He+ ions, resulting in a weaker stabilizing effect (i.e., larger growth rate). From the Probe B observations, we find that the growth rate becomes larger in the oxygen torus than in the adjacent regions in the plasma trough and the plasmasphere.

Inclination of Blumensaat's line influences on the accuracy of the quadrant method in evaluation for anterior cruciate ligament reconstruction

PURPOSE

The quadrant method is used to evaluate the bone tunnel position with the grid based on the Blumensaat's line in anterior cruciate ligament (ACL) reconstruction. This study aimed to clarify the influence of variation in the Blumensaat's line on the accuracy of the quadrant method measurements.

METHODS

A retrospective review of the radiological records of patients aged 18-30 years who underwent computed tomography (CT) scanning of the knee joint was conducted. The Blumensaat's line inclination angle (BIA), along with the most posterior point of the posterior condyle (point P) position using the quadrant method and morphology of the Blumensaat's line were measured on true lateral transparent three-dimensional CT images of the distal femoral condyle in 147 patients. Statistical analysis was conducted to determine associations among these measurements.

RESULTS

BIA was 37.5° (standard deviation 4.2°; range 27°-48°). The point P position was significantly correlated with BIA in the high/low (R² = 0.590, P < 0.0001) and deep/shallow (R² = 0.461, P < 0.0001) directions. The morphology of the Blumensaat's line was straight in 35 knees (23.8%); whereas, the remaining 112 knees (76.2%) were not straight but had some hill on the Blumensaat's line. No significant difference among the morphological variation of the Blumensaat's line was observed in BIA and the point P position.

CONCLUSION

There was a strong correlation between BIA and the point P measured using the quadrant method, suggesting the influence of the Blumensaat's line on the accuracy of the quadrant method measurements in ACL reconstruction. As for the clinical relevance, surgeons should be careful in application of the quadrant method for ACL reconstruction, because the variation of the Blumensaat's line inclination influences the accuracy of this method.

Multiple time-scale beats in aurora: precise orchestration via magnetospheric chorus waves

The brightness of aurorae in Earth’s polar region often beats with periods ranging from sub-second to a few tens of a second. Past observations showed that the beat of the aurora is composed of a superposition of two independent periodicities that co-exist hierarchically. However, the origin of such multiple time-scale beats in aurora remains poorly understood due to a lack of measurements with sufficiently high temporal resolution. By coordinating experiments using ultrafast auroral imagers deployed in the Arctic with the newly-launched magnetospheric satellite Arase, we succeeded in identifying an excellent agreement between the beats in aurorae and intensity modulations of natural electromagnetic waves in space called “chorus”. In particular, sub-second scintillations of aurorae are precisely controlled by fine-scale chirping rhythms in chorus. The observation of this striking correlation demonstrates that resonant interaction between energetic electrons and chorus waves in magnetospheres orchestrates the complex behavior of aurora on Earth and other magnetized planets.

Diagonal nematicity in the pseudogap phase of HgBa2CuO4+δ

The pseudogap phenomenon in the cuprates is arguably the most mysterious puzzle in the field of high-temperature superconductivity. The tetragonal cuprate HgBa₂CuO_4+δ, with only one CuO₂ layer per primitive cell, is an ideal system to tackle this puzzle. Here, we measure the magnetic susceptibility anisotropy within the CuO₂ plane with exceptionally high-precision magnetic torque experiments. Our key finding is that a distinct two-fold in-plane anisotropy sets in below the pseudogap temperature T^*, which provides thermodynamic evidence for a nematic phase transition with broken four-fold symmetry. Surprisingly, the nematic director orients along the diagonal direction of the CuO₂ square lattice, in sharp contrast to the bond nematicity along the Cu-O-Cu direction. Another remarkable feature is that the enhancement of the diagonal nematicity with decreasing temperature is suppressed around the temperature at which short-range charge-density-wave formation occurs. Our result suggests a competing relationship between diagonal nematic and charge-density-wave order in HgBa₂CuO_4+δ.

The Space Physics Environment Data Analysis System (SPEDAS)

With the advent of the Heliophysics/Geospace System Observatory (H/GSO), a complement of multi-spacecraft missions and ground-based observatories to study the space environment, data retrieval, analysis, and visualization of space physics data can be daunting. The Space Physics Environment Data Analysis System (SPEDAS), a grass-roots software development platform (www.spedas.org), is now officially supported by NASA Heliophysics as part of its data environment infrastructure. It serves more than a dozen space missions and ground observatories and can integrate the full complement of past and upcoming space physics missions with minimal resources, following clear, simple, and well-proven guidelines. Free, modular and configurable to the needs of individual missions, it works in both command-line (ideal for experienced users) and Graphical User Interface (GUI) mode (reducing the learning curve for first-time users). Both options have "crib-sheets," user-command sequences in ASCII format that can facilitate record-and-repeat actions, especially for complex operations and plotting. Crib-sheets enhance scientific interactions, as users can move rapidly and accurately from exchanges of technical information on data processing to efficient discussions regarding data interpretation and science. SPEDAS can readily query and ingest all International Solar Terrestrial Physics (ISTP)-compatible products from the Space Physics Data Facility (SPDF), enabling access to a vast collection of historic and current mission data. The planned incorporation of Heliophysics Application Programmer's Interface (HAPI) standards will facilitate data ingestion from distributed datasets that adhere to these standards. Although SPEDAS is currently Interactive Data Language (IDL)-based (and interfaces to Java-based tools such as Autoplot), efforts are under-way to expand it further to work with python (first as an interface tool and potentially even receiving an under-the-hood replacement). We review the SPEDAS development history, goals, and current implementation. We explain its "modes of use" with examples geared for users and outline its technical implementation and requirements with software developers in mind. We also describe SPEDAS personnel and software management, interfaces with other organizations, resources and support structure available to the community, and future development plans.

ELECTRONIC SUPPLEMENTARY MATERIAL

The online version of this article (10.1007/s11214-018-0576-4) contains supplementary material, which is available to authorized users.

Quantum oscillations of electrical resistivity in an insulator

In metals, orbital motions of conduction electrons on the Fermi surface are quantized in magnetic fields, which is manifested by quantum oscillations in electrical resistivity. This Landau quantization is generally absent in insulators. Here, we report a notable exception in an insulator-ytterbium dodecaboride (YbB₁₂). The resistivity of YbB₁₂, which is of a much larger magnitude than the resistivity in metals, exhibits distinct quantum oscillations. These unconventional oscillations arise from the insulating bulk, even though the temperature dependence of the oscillation amplitude follows the conventional Fermi liquid theory of metals with a large effective mass. Quantum oscillations in the magnetic torque are also observed, albeit with a lighter effective mass.

Pulsating aurora from electron scattering by chorus waves

Auroral substorms, dynamic phenomena that occur in the upper atmosphere at night, are caused by global reconfiguration of the magnetosphere, which releases stored solar wind energy. These storms are characterized by auroral brightening from dusk to midnight, followed by violent motions of distinct auroral arcs that suddenly break up, and the subsequent emergence of diffuse, pulsating auroral patches at dawn. Pulsating aurorae, which are quasiperiodic, blinking patches of light tens to hundreds of kilometres across, appear at altitudes of about 100 kilometres in the high-latitude regions of both hemispheres, and multiple patches often cover the entire sky. This auroral pulsation, with periods of several to tens of seconds, is generated by the intermittent precipitation of energetic electrons (several to tens of kiloelectronvolts) arriving from the magnetosphere and colliding with the atoms and molecules of the upper atmosphere. A possible cause of this precipitation is the interaction between magnetospheric electrons and electromagnetic waves called whistler-mode chorus waves. However, no direct observational evidence of this interaction has been obtained so far. Here we report that energetic electrons are scattered by chorus waves, resulting in their precipitation. Our observations were made in March 2017 with a magnetospheric spacecraft equipped with a high-angular-resolution electron sensor and electromagnetic field instruments. The measured quasiperiodic precipitating electron flux was sufficiently intense to generate a pulsating aurora, which was indeed simultaneously observed by a ground auroral imager.

Unusual Thermal Hall Effect in a Kitaev Spin Liquid Candidate α-RuCl_{3}

The Kitaev quantum spin liquid displays the fractionalization of quantum spins into Majorana fermions. The emergent Majorana edge current is predicted to manifest itself in the form of a finite thermal Hall effect, a feature commonly discussed in topological superconductors. Here we report on thermal Hall conductivity κ_{xy} measurements in α-RuCl_{3}, a candidate Kitaev magnet with the two-dimensional honeycomb lattice. In a spin-liquid (Kitaev paramagnetic) state below the temperature characterized by the Kitaev interaction J_{K}/k_{B}∼80  K, positive κ_{xy} develops gradually upon cooling, demonstrating the presence of highly unusual itinerant excitations. Although the zero-temperature property is masked by the magnetic ordering at T_{N}=7  K, the sign, magnitude, and T dependence of κ_{xy}/T at intermediate temperatures follows the predicted trend of the itinerant Majorana excitations.

Tuning the Pairing Interaction in a d-Wave Superconductor by Paramagnons Injected through Interfaces

Unconventional superconductivity and magnetism are intertwined on a microscopic level in a wide class of materials. A new approach to this most fundamental and hotly debated issue focuses on the role of interactions between superconducting electrons and bosonic fluctuations at the interface between adjacent layers in heterostructures. Here we fabricate hybrid superlattices consisting of alternating atomic layers of the heavy-fermion superconductor CeCoIn_{5} and antiferromagnetic (AFM) metal CeRhIn_{5}, in which the AFM order can be suppressed by applying pressure. We find that the superconducting and AFM states coexist in spatially separated layers, but their mutual coupling via the interface significantly modifies the superconducting properties. An analysis of upper critical fields reveals that, upon suppressing the AFM order by applied pressure, the force binding superconducting electron pairs acquires an extreme strong-coupling nature. This demonstrates that superconducting pairing can be tuned nontrivially by magnetic fluctuations (paramagnons) injected through the interface.

Preoperative knee deformity and kinematics impact postoperative knee kinematics in total knee arthroplasty

BACKGROUND

The purpose of this study was to evaluate the relationship between the preoperative knee deformity/kinematic pattern and the postoperative knee kinematic pattern in posterior cruciate ligament substituting (PS)-total knee arthroplasty (TKA).

METHODS

This study involved 39 patients with medial osteoarthritis who underwent a primary PS-TKA using a computed-tomography-based navigation system. All the operations were performed by a single surgeon using a subvastus approach, modified gap technique and the same PS type of prosthesis (Genesis II™ total knee system, Smith & Nephew, Memphis, TN, USA). Knee deformity, kinematic pattern after capsule incision (preoperative knee kinematics), and kinematic pattern after implantation (postoperative knee kinematics) in PS-TKA were measured. Kinematic patterns were divided into two groups: a medial pivot group and a non-medial pivot group.

RESULTS

Preoperative varus knee deformity was significantly larger in the non-medial pivot group than in the medial pivot group (femorotibial angle: 184.7±6.4° vs. 180.8±3.9°, P<0.05). In addition, preoperative knee kinematics were conserved postoperatively, at a rate of 82% (P<0.01).

CONCLUSIONS

The severity of varus knee deformity and the preoperative knee kinematic pattern might have affected the postoperative knee kinematics in PS-TKA. This must be confirmed with a randomized controlled trial on a large population study.

LEVEL OF EVIDENCE

case control study, Level III.

Full-Gap Superconductivity Robust against Disorder in Heavy-Fermion CeCu_{2}Si_{2}

A key aspect of unconventional pairing by the antiferromagnetic spin-fluctuation mechanism is that the superconducting energy gap must have the opposite sign on different parts of the Fermi surface. Recent observations of non-nodal gap structure in the heavy-fermion superconductor CeCu_{2}Si_{2} were then very surprising, given that this material has long been considered a prototypical example of a superconductor where the Cooper pairing is magnetically mediated. Here we present a study of the effect of controlled point defects, introduced by electron irradiation, on the temperature-dependent magnetic penetration depth λ(T) in CeCu_{2}Si_{2}. We find that the fully gapped state is robust against disorder, demonstrating that low-energy bound states, expected for sign-changing gap structures, are not induced by nonmagnetic impurities. This provides bulk evidence for s_{++}-wave superconductivity without sign reversal.

FUT2 non-secretor status is associated with Type 1 diabetes susceptibility in Japanese children

AIM

To examine the contribution of the FUT2 gene and ABO blood type to the development of Type 1 diabetes in Japanese children.

METHODS

We analysed FUT2 variants and ABO genotypes in a total of 531 Japanese children diagnosed with Type 1 diabetes and 448 control subjects. The possible association of FUT2 variants and ABO genotypes with the onset of Type 1 diabetes was statistically examined.

RESULTS

The se2 genotype (c.385A>T) of the FUT2 gene was found to confer susceptibility to Type 1A diabetes in a recessive effects model [odds ratio for se2/se2, 1.68 (95% CI 1.20-2.35); corrected P value = 0.0075].

CONCLUSIONS

The FUT2 gene contributed to the development of Type 1 diabetes in the present cohort of Japanese children.

Variants associated with autoimmune Type 1 diabetes in Japanese children: implications for age-specific effects of cis-regulatory haplotypes at 17q12-q21

AIMS

The aim of this study was to clarify the significance of previously reported susceptibility variants in the development of autoimmune Type 1 diabetes in non-white children. Tested variants included rs2290400, which has been linked to Type 1 diabetes only in one study on white people. Haplotypes at 17q12-q21 encompassing rs2290400 are known to determine the susceptibility of early-onset asthma by affecting the expression of flanking genes.

METHODS

We genotyped 63 variants in 428 Japanese people with childhood-onset autoimmune Type 1 diabetes and 457 individuals without diabetes. Possible association between variants and age at diabetes onset was examined using age-specific quantitative trait locus analysis and ordered-subset regression analysis.

RESULTS

Ten variants, including rs2290400 in GSDMB, were more frequent among the people with Type 1 diabetes than those without diabetes. Of these, rs689 in INS and rs231775 in CTLA4 yielded particularly high odds ratios of 5.58 (corrected P value 0.001; 95% CI 2.15-14.47) and 1.64 (corrected P value 5.3 × 10^-5 ; 95% CI 1.34-2.01), respectively. Age-specific effects on diabetes susceptibility were suggested for rs2290400; heterozygosity of the risk alleles was associated with relatively early onset of diabetes, and the allele was linked to the phenotype exclusively in the subgroup of age at onset ≤ 5.0 years.

CONCLUSIONS

The results indicate that rs2290400 in GSDMB and polymorphisms in INS and CTLA4 are associated with the risk of Type 1 diabetes in Japanese children. Importantly, cis-regulatory haplotypes at 17q12-q21 encompassing rs2290400 probably determine the risk of autoimmune Type 1 diabetes predominantly in early childhood.

Effects of Multiple Intra-articular Injections of 0.5% Bupivacaine on Normal and Osteoarthritic Joints in Rats

PURPOSE

To determine the in vivo effects of multiple local anesthetic injections of 0.5% bupivacaine on normal and osteoarthritic articular cartilage.

METHODS

Rats with normal knee joints received an intra-articular injection of 0.9% saline solution or 0.5% bupivacaine in their right knees joint once a week for 5 consecutive weeks, starting 4 weeks after the beginning of the experiment. Rats were humanely killed at 8, 16, and 24 weeks. In a parallel experiment, rats underwent anterior cruciate ligament transection to induce osteoarthritic changes. These rats were subjected to the same protocol as those with normal knee joints, starting 4 weeks after the procedure. Static weight-bearing tests were performed on both hind limbs to evaluate changes in weight-bearing ability throughout the experiments. Rats were humanely killed at 8 and 16 weeks. Cell viability was assessed with confocal microscopy, using samples from the distal femur. Histologic assessment of osteoarthritis was performed using samples from the tibial plateau based on the Osteoarthritis Research Society International (OARSI) cartilage histopathology assessment system (i.e., OARSI score).

RESULTS

Static weight-bearing tests showed no significant changes after intra-articular injection of saline solution or bupivacaine, and bupivacaine injection did not increase weight bearing compared with saline solution injection, regardless of whether there were osteoarthritic changes. There were also no significant differences in cell viability, cell density, or OARSI scores between the saline solution and bupivacaine groups at each time point, regardless of whether osteoarthritic changes were induced.

CONCLUSIONS

This study suggested that single or intermittent intra-articular bupivacaine injections might not have deleterious effects on either osteoarthritic or normal joints.

CLINICAL RELEVANCE

There is no strong evidence that intra-articular bupivacaine injection induces degenerative changes in articular cartilage. Therefore, these results may apply to normal and osteoarthritic joints.

Tuning the Magnetic Quantum Criticality of Artificial Kondo Superlattices CeRhIn_{5}/YbRhIn_{5}

The effects of reduced dimensions and the interfaces on antiferromagnetic quantum criticality are studied in epitaxial Kondo superlattices, with alternating n layers of heavy-fermion antiferromagnet CeRhIn_{5} and seven layers of normal metal YbRhIn_{5}. As n is reduced, the Kondo coherence temperature is suppressed due to the reduction of effective Kondo screening. The Néel temperature is gradually suppressed as n decreases and the quasiparticle mass is strongly enhanced, implying dimensional control toward a quantum critical point. Magnetotransport measurements reveal that a quantum critical point is reached for the n=3 superlattice by applying small magnetic fields. Remarkably, the anisotropy of the quantum critical field is opposite to the expectations from the magnetic susceptibility in bulk CeRhIn_{5}, suggesting that the Rashba spin-orbit interaction arising from the inversion symmetry breaking at the interface plays a key role for tuning the quantum criticality in the two-dimensional Kondo lattice.

Region-specific dendritic spine loss of pyramidal neurons in dopamine transporter knockout mice

Dopamine transporter (DAT) knockout (KO) mice show numerous behavioral alterations, including hyperlocomotion, cognitive deficits, impulsivity and impairment of prepulse inhibition of the startle reflex (PPI), phenotypes that may be relevant to frontostriatal disorders such as schizophrenia. Dendritic spine changes of pyramidal neurons in the dorsolateral prefrontal cortex (DLPFC) are among the most replicated of findings in postmortem studies of schizophrenia. The mechanisms that account for dendritic changes in the DLPFC in schizophrenia are unclear. Here, we report basal spine density of pyramidal neurons in the medial prefrontal cortex (mPFC), the motor cortex, the CA1 region of the hippocampus, and the basolateral amygdala in DAT KO mice. Pyramidal neurons were visualized using DAT KO mice crossbred with a Thy1-GFP transgenic mouse line. We observed a significant decrease in spine density of pyramidal neurons in the mPFC and the CA1 region of the hippocampus in DAT KO mice compared to that in WT mice. On the other hand, no difference was observed in spine density of pyramidal neurons in the motor cortex or the basolateral amygdala between DAT genotypes. These results suggest that decreased spine density could cause hypofunction of the mPFC and the hippocampus, and contribute to the behavioral abnormalities observed in DAT KO mice, including cognitive deficits. This might suggest that aberrant dopaminergic signaling may trigger dystrophic changes in dendrites of hippocampal and prefrontocortical pyramidal neurons in schizophrenia.

A Comparative Study With In Vitro Ultrasonographic and Histologic Grading of Metatarsal Head Cartilage in Rheumatoid Arthritis

BACKGROUND

Ultrasonography is among the valid methods to assess articular cartilage in the foot. This study aimed to evaluate the validity of ultrasonographic grading to assess metatarsal head articular cartilage for rheumatoid forefoot deformity in vivo and to compare the findings with in vitro ultrasonographic and histologic gradings.

METHODS

Participants were 15 patients scheduled to undergo resection arthroplasty of the metatarsal heads of the lesser toes because of rheumatoid arthritis of the metatarsophalangeal joints. Ultrasonographic examination was performed in vivo the day before surgery. Specimens of the second to fifth metatarsal heads taken intraoperatively were graded from in vitro ultrasonographic and histologic evaluations. Correlations among in vivo ultrasonographic, in vitro ultrasonographic, and histologic gradings were analyzed.

RESULTS

In 46 metatarsal heads, the distribution of grading ranged from grade 1 to 6 for in vivo ultrasonographic examinations and from grade 1 to 4 for histologic examinations. In vivo ultrasonographic grading showed significant correlation to both in vitro ultrasonographic grading (P < .001, R = 0.74) and histologic grading (P < .001, R = 0.67).

CONCLUSIONS

The significant correlations between in vivo ultrasonographic and histologic gradings suggest that a semiquantitative in vivo ultrasonographic assessment of forefoot deformity in rheumatoid arthritis may be possible. Ultrasonographic grading may prove useful for pre- and postoperative evaluation of remaining joint function in rheumatoid forefoot deformity. An ultrasonographic grading system for remaining joint surfaces might be helpful in selecting surgical procedures such as joint-sparing osteotomy and metatarsal head resection.

LEVEL OF EVIDENCE

Level IV, case series.

Therapeutic effects of intra-articular ultra-purified low endotoxin alginate administration on an experimental canine osteoarthritis model

OBJECTIVE

This study aimed to elucidate the therapeutic effects of intra-articular administration of ultra-purified low endotoxin alginate (UPLE-alginate) on osteoarthritis (OA) using a canine anterior cruciate ligament transection (ACLT) model.

DESIGN

We used 20 beagle dogs. ACLT was performed on the left knee of each dog and a sham operation was performed on the right knee as a control. All animals were randomly divided into the control (saline) and therapeutic (UPLE-alginate) groups. Animals in the control and therapeutic groups received weekly injections with 0.7 mL normal saline or 0.7 mL 0.5% UPLE-alginate, respectively, from 0 to 3 weeks after ACLT or sham operation. At 9 weeks after ACLT, the knee joints of all animals were observed using arthroscopy. All animals were euthanized at 14 weeks after ACLT and evaluated using morphologic assessment, histologic assessment, and biomechanical testing.

RESULTS

Arthroscopic findings showed intact cartilage surface in both groups. Morphologic findings in the therapeutic group showed milder degeneration compared with those of the control group, but there were no significant differences between groups. Histologic scores of the medial femoral condyle (MFC) and lateral femoral condyle (LFC) were better in the therapeutic group than the control group (MFC: p = 0.009, LFC: p = 0.009). Joint lubrication did not differ significantly between groups.

CONCLUSION

Intra-articular administration of UPLE-alginate in the early stage of OA slowed disease progression in canines. UPLE-alginate may have potential as a therapeutic agent for OA patients and reduce the number of patients who need to undergo total joint arthroplasty.

The regulation of oxytocin receptor gene expression during adipogenesis

Although it has been reported that oxytocin stimulates lipolysis in adipocytes, changes in the expression of oxytocin receptor (OTR) mRNA in adipogenesis are still unknown. The present study aimed to investigate the expression of OTR mRNA during adipocyte differentiation and fat accumulation in adipocytes. OTR mRNA was highly expressed in adipocytes prepared from mouse adipose tissues compared to stromal-vascular cells. OTR mRNA expression was increased during the adipocyte differentiation of 3T3-L1 cells. OTR expression levels were higher in subcutaneous and epididymal adipose tissues of 14-week-old male mice compared to 7-week-old male mice. Levels of OTR mRNA expression were higher in adipose tissues at four different sites of mice fed a high-fat diet than in those of mice fed a normal diet. The OTR expression level was also increased by refeeding for 4 h after fasting for 16 h. Oxytocin significantly induced lipolysis in 3T3-L1 adipocytes. In conclusion, a new regulatory mechanism is demonstrated for oxytocin to control the differentiation and fat accumulation in adipocytes via activation of OTR as a part of the hypothalamic-pituitary-adipose axis.

Correlation between knee kinematics and patellofemoral contact pressure in total knee arthroplasty

The aim of this study is to evaluate the relationship between patellofemoral contact stress and intraoperative knee kinematic patterns after mobile bearing total knee arthroplasty (TKA). Medial osteoarthritic knees of forty-six posterior-stabilized total knee prostheses were evaluated using a computed tomography-guided navigation system. Subjects were divided into two groups based on intraoperative knee kinematic patterns: the medial pivot group (n=19) and the non-medial pivot group (n=27). Mean intraoperative patello-femoral contact stress was significantly lower in the medial pivot group than in the non-medial pivot group (1.7MPa vs. 3.2MPa, P<0.05). An intraoperative medial pivot pattern results in reduced patello-femoral contact stress.

Intraoperative medial pivot affects deep knee flexion angle and patient-reported outcomes after total knee arthroplasty

The aim of this study was to evaluate the relationship between clinical results including patient-reported outcomes and intraoperative knee kinematic patterns after total knee arthroplasty (TKA). A cross-sectional survey of forty consecutive medial osteoarthritis patients who had a primary TKA using a CT-based navigation system was conducted. Subjects were divided into two groups based on intraoperative kinematic patterns: a medial pivot group (n = 20) and a non-medial pivot group (n = 20). Subjective outcomes with the new Knee Society Score and clinical outcomes were evaluated. The functional activities, patient satisfaction and the knee flexion angle of the medial pivot group were significantly better than those of the non-medial pivot group. An intraoperative medial pivot pattern positively influences deep knee flexion and patient-reported outcomes.

Activin A is stimulated by tumor necrosis factor-alpha and modulates collagen gene expression in human amniotic cells

BACKGROUND

Accumulating evidence supports the idea of activin A as a modulator of inflammation. In human pregnancy, elevated activin A concentrations in amniotic fluid are reported in women with intra-amniotic infection and inflammation- induced pre-term birth.

AIM

To test the hypothesis that activin A was involved in the pathophysiology of amnionitis, we evaluated the effects of tumor necrosis factor-α and lipopolysaccharide on activin A production in human amniotic epithelial cells, and the effects of activin A on the expression of collagen mRNA in amniotic mesenchymal cells.

MATERIALS AND METHODS

Amniotic membranes were obtained from patients without systemic disease, signs of premature delivery or fetal complications, during elective cesarean sections at term. Amniotic epithelial cells and mesenchymal cells were separately obtained by enzymatic digestion and cultured. Activin A was measured by enzyme-linked immunosorbent assay and collagen mRNA levels were assessed by quantitative PCR.

RESULTS

Amniotic epithelial cells produced activin A in a cell density- and time-dependent manner. Tumor necrosis factor- α enhanced activin A production in a time-dependent (48-120 h) and dose-dependent (10-300 ng/ml) manner in amniotic epithelial cells. Lipopolysaccharide also stimulated activin A production, but the effect was less prominent. In amniotic mesenchymal cells, the effect of activin A on the expression of type I and type III collagen mRNA was suppressive.

CONCLUSIONS

Tumor necrosis factor-α and lipopolysaccharide stimulated activin A production in amniotic epithelial cells, and activin A modulated expression of collagen mRNA in amniotic mesenchymal cells. These results support the idea that activin A is involved in the pathophysiology of amnionitis.

What are the causes of revision total knee arthroplasty in Japan?

BACKGROUND

There is limited information regarding the cause of revision TKA in Asia, especially Japan. Owing to differences in patient backgrounds and lifestyles, the modes of TKA failures in Asia may differ from those in Western countries.

QUESTIONS/PURPOSES

We therefore determined (1) causes of revision TKA in a cohort of Japanese patients with revision TKA and (2) whether patient demographic features and underlying diagnosis of primary TKA are associated with the causes of revision TKA.

METHODS

We assessed all revision TKA procedures performed at five major centers in Hokkaido from 2006 to 2011 for the causes of failures. Demographic data and underlying diagnosis for index primary TKA of the revision cases were compared to those of randomly selected primary TKAs during the same period.

RESULTS

One hundred forty revision TKAs and 4047 primary TKAs were performed at the five centers, indicating a revision burden of 3.3%. The most common cause of revision TKA was mechanical loosening (40%) followed by infection (24%), wear/osteolysis (9%), instability (9%), implant failure (6%), periprosthetic fracture (4%), and other reasons (8%). The mean age of patients with periprosthetic fracture was older (77 versus 72 years) and the male proportion in patients with infection was higher (33% versus 19%) than those of patients in the primary TKA group. There was no difference in BMI between primary TKAs and any type of revision TKA except other causes.

CONCLUSIONS

The revision burden at the five referral centers in Hokkaido was 3.3%, and the most common cause of revision TKA was mechanical loosening followed by infection. Demographic data such as age and sex might be associated with particular causes of revision TKA.

Sagittal alignment of the first metatarsophalangeal joint after arthrodesis for rheumatoid forefoot deformity

The present study assessed the midterm results of reconstruction for rheumatoid forefoot deformity with arthrodesis of the first metatarsophalangeal (MTP) joint, scarf osteotomy, resection arthroplasty of the metatarsal head of the lesser toes, and surgical repair of hammertoe deformity (arthrodesis of the proximal interphalangeal joint). Special focus was placed on the sagittal alignment of the first metatarsophalangeal joint after arthrodesis. We retrospectively evaluated the postoperative clinical outcomes and radiographic findings for 16 consecutive female patients (20 feet) with symptomatic rheumatoid forefoot deformities. The mean duration of follow-up was 7.9 (range 4 to 13) years. All first MTP joints and first metatarsal bones were fused successfully. The mean value of the American Orthopaedic Foot and Ankle Society and Japanese Society for Foot Surgery clinical scores significantly improved overall, except for 2 patients (10%), who complained of first toe pain at the final follow-up visit owing to sagittal misalignment of the fused first MTP joint. Sagittal alignment of the first metatarsal varies greatly because of the rheumatoid midfoot and hindfoot deformities. Therefore, inclination of the first metatarsal should be considered when determining the first MTP joint sagittal fusion angle.

Correlation-enhanced effective mass of two-dimensional electrons in Mg(x)Zn(1-x)O/ZnO heterostructures

We performed combined magnetotransport and cyclotron resonance experiments on two-dimensional electron systems confined in the Mg(x)Zn(1-x)O/ZnO heterostructures over a wide range of carrier densities, from 1.9 to 12 × 10(11) cm(-2) (3.5 </~ r(s) </~ 10, where r(s) is the Wigner-Seitz radius). As the carrier density was reduced, the transport mass m(tr)* was strongly enhanced. In marked contrast, the effective masses determined from the cyclotron resonance m(CR)(*) were found to be independent of the carrier density and as large as the bulk effective mass. The large enhancement of m(tr)(*), which exceeds m(CR)(*) by ~ 60%, at the lowest carrier density with r(s) 10 is purely attributed to the strong electron correlation.

Relation between maximum phonation time and exercise capacity in chronic heart failure patients

BACKGROUND

Patients with chronic heart failure (CHF) commonly fatigue easily due to low peak oxygen uptake (peak VO(2)), an important index of exercise capacity. Maximum phonation time (MPT) is widely used to evaluate maximum vocal capabilities because it is non-invasive, quick, and inexpensive.

AIM

The aim of this study was to determine the relation between MPT and exercise capacity, and MPT required to attain an exercise capacity of ≥5 metabolic equivalents (METs) in CHF outpatients.

DESIGN

Cross-sectional study.

SETTING

Outpatient cardiac rehabilitation unit.

POPULATION

We enrolled 111 CHF outpatients (mean age 54.2±10.1 years).

METHODS

Peak VO(2) was assessed during cardiopulmonary exercise testing (CPX) as the index of exercise capacity. After CPX, we divided the patients into two groups according to exercise capacity: ≥5 METs group (N.=68) and <5 METs group (N.=43). Measurements of MPT were taken in the seated position. All patients were asked to produce a sustained vowel /a:/ for as long as possible and were verbally encouraged during respiratory effort.

RESULTS

After adjustment for patient clinical characteristics, MPT in the CHF patients was found to be significantly higher in the ≥5 METs group than in the <5 METs group (22.1±8.4 vs. 17.0±11.6 s, F=13.5, P<0.001). Receiver-operating characteristic curve analysis of exercise capacity of ≥5 METs extracted a cutoff value for MPT of 18.27 s, with a sensitivity of 0.76, 1-specificity of 0.33, and AUC value of 0.81 (95% CI: 0.70-0.87, P<0.001).

CONCLUSION

There were differences in MPT in relation to an exercise capacity threshold of ≥5 METs in CHF outpatients. A MPT of 18.27 sec may be the best cutoff value to identify people with or without exercise capacity of ≥5 METs.

CLINICAL REHABILITATION IMPACT

Measurement of MPT may be a useful method for estimating exercise capacity in CHF outpatients.

Outcome of transfibular ankle arthrodesis with Ilizarov apparatus

BACKGROUND

Both transfibular ankle arthrodesis with fibular onlay grafting and ankle arthrodesis using the Ilizarov apparatus have resulted in acceptable fusion rates. This study analyzed outcomes in the authors' practice for all patients who underwent transfibular ankle arthrodesis with fibular onlay grafting using the Ilizarov apparatus.

MATERIALS AND METHODS

A retrospective review was conducted of all patients who experienced severe ankle pain associated with osteoarthritis, rheumatoid arthritis, talar osteonecrosis, or septic arthritis and underwent transfibular ankle arthrodesis with an Ilizarov apparatus between 1995 and 2010. Postoperative clinical outcomes were evaluated for 42 consecutive patients (43 feet) who received primary or revision ankle arthrodesis using the Ilizarov technique at two centers. Mean duration of follow-up was 4.1 (range, 1.5 to 13) years. Outcomes were assessed using the ankle-hindfoot scale of the American Orthopaedic Foot and Ankle Society.

RESULTS

All ankles fused successfully. Mean clinical outcome improved significantly from 36.2 (range, 8 to 64) preoperatively to 77.4 (range, 0 to 86; p < .05) postoperatively.

CONCLUSION

Transfibular ankle arthrodesis using the Ilizarov external fixation system and fibular onlay strut grafting can achieve a very high rate of bony union and lead to general improvements in clinical outcome. Forefoot stabilization with a forefoot ring achieved rigid stabilization resulting in a shorter duration of external fixation.

Eating alone among community-dwelling Japanese elderly: association with depression and food diversity

Eating alone is an emerging social concern these days along with the background of serious aging population growth and increasing number of single-dwellers in Japan. However, little study is focused eating alone and its relation to the health status of community-dwelling elderly.

OBJECTIVES

To clarify the relations between eating alone and geriatric functions such as depression, quantitative subjective quality of life (QOL), activities of daily living (ADL) and dietary status of community-dwelling Japanese elderly.

DESIGN

A cross-sectional study.

SETTINGS

Tosa town, one of the "super-aged" towns in Japan.

PARTICIPANTS

The study population consisted of 856 community-dwelling elderly aged ≥65 living in Tosa town.

MEASUREMENTS

Eating alone and living arrangement was defined by the questionnaire. Geriatric functions were assessed by measuring activities of daily living (ADL), depressive symptom using 15-item geriatric depression scale (GDS-15), and quality of life (QOL). Food diversity was investigated as a measure of dietary quality using 11-item Food Diversity Score Kyoto (FDSK-11). Body mass index (BMI) was calculated using height and body weight during a medical assessment.

RESULTS

The proportion of the elderly who usually eat alone was 33.2% in this study population. Even among 697 elderly subjects who live with others, 136 persons (19.5%) ate alone. The participants who ate alone were significantly depressed according to the assessment using GDS-15 score (5.7±4.3 vs. 4.4±3.8, P<0.001). Those who ate alone have lower scores of QOL items than those who ate with others (Subjective sense of health: 52.5±21.9 vs. 55.7±20.2 P=0.035, Relationship with family: 74.1±23.5 vs. 78.9±18.6 P<0.001, Subjective happiness: 58.5±22.7 vs. 62.2±21.1 P=0.019). A significant close association was found between eating alone and lower food diversity (FDSK-11 score 9.9±1.3 vs. 10.2±1.3, P=0.002). BMI was lower in the elderly subjects who ate alone than those with others. By the multivariate analysis, depression was independently associated with eating alone in the logistic regression model adjusted for age, sex, BMI and food diversity as confounding factors (OR: 1.42, CI: 1.00-2.11, P=0.043). Food diversity was also significantly associated even after the adjustment of these confounding factors.

CONCLUSION

Eating alone is an important issue related to depression and QOL as well as dietary status of community-dwellingl elderly in Japan. This study shows the simple and inexpensive way "eating together" may contribute to improve depressive mood of elderly persons, with a strong message that supports of family, friends and neighbors are very important.

Ganglioside GM3 has an essential role in the pathogenesis and progression of rheumatoid arthritis

Rheumatoid arthritis (RA), a chronic systemic inflammatory disorder that principally attacks synovial joints, afflicts over 2 million people in the United States. Interleukin (IL)-17 is considered to be a master cytokine in chronic, destructive arthritis. Levels of the ganglioside GM3, one of the most primitive glycosphingolipids containing a sialic acid in the structure, are remarkably decreased in the synovium of patients with RA. Based on the increased cytokine secretions observed in in vitro experiments, GM3 might have an immunologic role. Here, to clarify the association between RA and GM3, we established a collagen-induced arthritis mouse model using the null mutation of the ganglioside GM3 synthase gene. GM3 deficiency exacerbated inflammatory arthritis in the mouse model of RA. In addition, disrupting GM3 induced T cell activation in vivo and promoted overproduction of the cytokines involved in RA. In contrast, the amount of the GM3 synthase gene transcript in the synovium was higher in patients with RA than in those with osteoarthritis. These findings indicate a crucial role for GM3 in the pathogenesis and progression of RA. Control of glycosphingolipids such as GM3 might therefore provide a novel therapeutic strategy for RA.

Effect of the Japanese herbal medicine, Boiogito, on the osteoarthritis of the knee with joint effusion

Background

Boiogito (Japanese herbal medicine, Tsumura Co. Tokyo, Japan) contains sinomenin which inhibits inflammatory reactions. Since sinomenine is a principle component of the Boiogito, there is a possibility of it being effective on osteoarthritis (OA) of the knee with joint effusion. However, there is no report concerning the effectiveness of Boiogito on knee OA. The objective of the present study is to investigate the therapeutic effect of Boiogito on OA of the knee associated with joint effusion in a comparative study among randomly assigned groups.

Methods

Study was performed using 50 patients who were diagnosed with primary osteoarthritis of the knee with joint effusion. The patients were randomly assigned to two groups: one group (25 patients) using both loxoprofen (2-{4-[(2-oxocyclopentyl) methyl]} propanoic acid) and Boiogito and the other group (25 patients) using loxoprofen, and were evaluated during a 12 week observation period. The assessment parameters including knee scores in the Knee Society Rating System including Knee score and Functional scores, amount of joint effusion by joint puncture in clinically detected cases, the 36-items short form of the Medical Outcome Study Questionnaire (SF-36) as a measurement of health related quality of life were used.

Results

The knee scores based on the Knee Society Rating System were improved in both groups. The staircase climbing up and down ability in the Knee society rating system functional score was significantly improved in the group using Boiogito and loxoprofen compared to the loxoprofen group. In the evaluation using SF-36, significant improvements were found in the scores in both groups in physical functioning after 12 weeks. The amount of joint fluid was significantly decreased at 4, 8 and 12 weeks compared to pre-administration baseline in the group using Boiogito and loxoprofen. A side effect of Boiogito, dry mouth, was found in one case. The symptom was mild and improved immediately after discontinuation of administration.

Conclusion

The results indicated that Boiogito have a possibility for a treatment modality for joint effusion with osteoarthritis of the knee.

Risk of deep venous thrombosis in drain clamping with tranexamic acid and carbazochrome sodium sulfonate hydrate in total knee arthroplasty

The aim of this randomized prospective study was to clarify risks associated with a drain-clamping method using tranexamic acid and carbazochrome sodium sulfonate hydrate after total knee arthroplasty (TKA). Subjects comprised 100 patients scheduled to undergo TKA, randomized into 2 groups: 50 patients received the drain-clamping method using tranexamic acid and carbazochrome sodium sulfonate hydrate and 50 patients received drain-clamping with saline. Although bleeding volume was significantly lower in the group with tranexamic acid and carbazochrome sodium sulfonate hydrate, risk of asymptomatic deep venous thrombosis as detected by ultrasonography was comparable between groups. Tranexamic acid and carbazochrome sodium sulfonate hydrate in the drain-clamping method help reduce bleeding after TKA without increasing the risk of deep venous thrombosis.

Therapeutic Effects of Intra-Articular Ultrapurified Low Endotoxin Alginate Administration on Experimental Osteoarthritis in Rabbits

OBJECTIVE

We have developed an ultrapurified low endotoxin alginate (UPLE alginate), which can drastically reduce endotoxin levels. Our purposes were to examine the effects of UPLE alginate administration on osteoarthritis (OA) progression and to determine the adequate molecular weight of the UPLE alginate for therapeutic effects.

DESIGN

To induce knee OA, 35 Japanese White rabbits underwent anterior cruciate ligament transection. Intra-articular injections of 0.3 mL solution of each material were started at 4 weeks postoperatively for a total of 5 weekly injections. Seventy knees were divided into the following groups: AL430 (430 kDa molecular weight UPLE alginate), AL1000 (1,000 kDa), AL1700 (1,700 kDa), HA (hyaluronan), and NS (normal saline). At 9 weeks postoperatively, all knees were assessed macroscopically, histologically, and mechanically.

RESULTS

Macroscopically, the UPLE alginate groups exhibited milder cartilage degradation compared to that of the NS and HA groups. Histological findings of the UPLE alginate groups showed an obvious reduction in the severity of OA. The histological scores of Kikuchi et al. were superior in the alginate treatment groups compared to the NS group. The friction coefficient of the AL1000 group was significantly lower than that of the NS and HA groups.

CONCLUSION

This study indicates that our UPLE alginates, especially AL1000, have promising potential as an effective agent in preventing OA progression.

Repair of articular cartilage defects with a novel injectable in situ forming material in a canine model

We developed an ultra-purified in situ forming gel as an injectable delivery vehicle of bone marrow stromal cells (BMSCs). Our objective was to assess reparative tissues treated with autologous BMSCs implanted using the injectable implantation system into osteochondral defects in a canine model. Forty-eight osteochondral defects in the patella groove of the knee joint were created in 12 adult beagle dogs (two defects in each knee). The defects were divided into a defect group (n = 16), an acellular novel material implantation (material) group (n = 16), and a BMSCs implantation using the current vehicle system (material with BMSCs) group (n = 16). The reparative tissues at 16 weeks postoperatively were assessed through gross, histological, and mechanical analyses. The reparative tissues of the material with BMSCs group were substituted with firm and smooth hyaline-like cartilage tissue that was perfectly integrated into the host tissues. This treatment group obviously enhanced the subchondral bone reconstruction. The compressive modulus of the reparative tissues was significantly higher in the material with BMSCs group than the other groups. This study demonstrated that the implantation of BMSCs using our novel in situ forming material induced a mature hyaline-like cartilage repair of osteochondral defects in a canine model.