Associations of disease duration and anti-citrullinated peptide antibody status with the effectiveness of abatacept in biologic-naïve patients with rheumatoid arthritis: Post hoc analysis of a multicentre, real-world observational study in Japan (ORIGAMI)

OBJECTIVES

The aim of the article is to investigate the associations of disease duration and anti-cyclic citrullinated peptide antibody (ACPA) status with the effectiveness of abatacept in biologic-naïve patients with rheumatoid arthritis (RA).

METHODS

We performed post hoc analyses of the Orencia® Registry in Geographically Assembled Multicenter Investigation (ORIGAMI) study of biologic-naïve RA patients aged ≥20 years with moderate disease activity who were prescribed abatacept. Changes in the Simplified Disease Activity Index (SDAI) and Japanese Health Assessment Questionnaire (J-HAQ) at 4, 24, and 52 weeks of treatment were analysed in patients divided according to ACPA serostatus (positive/negative), disease duration (<1/≥1 year), or both.

RESULTS

SDAI scores decreased from baseline in all groups. SDAI scores tended to decrease more in the ACPA-positive group and disease duration <1-year group than in the ACPA-negative group and disease duration ≥1-year group, respectively. In the disease duration <1-year group, SDAI tended to decrease more in the ACPA-positive group than in the ACPA-negative group. Disease duration was independently associated with the change in SDAI and SDAI remission at Week 52 in multivariable regression models.

CONCLUSIONS

These results suggest that starting abatacept within 1 year of diagnosis was associated with greater effectiveness of abatacept in biologic-naïve patients with RA and moderate disease activity.

Cytokine Profile From the Ligamentum Flavum in Patients with Ossification of the Posterior Longitudinal Ligament in the Cervical Spine

STUDY DESIGN

Histological, immunohistochemical, and suspension array analyses of cytokine expression in human cervical ossification of the posterior longitudinal ligament (OPLL).

OBJECTIVES

The aim of this study was to determine whether changes in the cytokine profile reflect the maturation of chondrocytes and osteoblasts are associated with OPLL development.

SUMMARY OF BACKGROUND DATA

OPLL progresses gradually over a prolonged period and may lead to serious spinal cord complications. However, treatment methods only include conservative therapy for neurological symptoms or surgical decompression, whereas preventive therapy for OPLL remains nonexistent.

METHODS

Ligamentous samples were harvested from 24 patients with OPLL who underwent spinal surgery, and five control samples from cervical spondylotic myelo/radiculopathy patients without OPLL. Tissue sections were used for immunohistochemical studies and primary cells were cultured from the ligamentous samples for cytokine profiling. Using a suspension array system, concentrations of 27 inflammatory cytokines or growth factors were measured to generate the cytokine profiles.

RESULTS

Suspension array and immunoblot analysis revealed significant increments in the levels of interleukin (IL)-6, IL-1α, basic fibroblast growth factor, and RANTES in patients with OPLL. Immunohistochemical analysis further revealed that these factors were present in mesenchymal cells within the degenerative portion of the ligamentous matrix.

CONCLUSION

Our findings suggest that specific changes in the cytokine profile during ossification promote osteoblast differentiation, thereby providing new insights into OPLL pathogenesis. Moreover, this work supports the development of a new therapeutic method for preventing OPLL progression by regulating the cytokine profiles.Level of Evidence: 3.

Surgical Treatment of Wrist Joint Dysfunction in Rheumatoid Arthritis: A Report of Two Cases

In rheumatoid arthritis (RA), it is important to actively treat wrist dysfunction to improve patient outcomes. Herein, we report two cases of wrist dysfunction in RA patients who required partial wrist fusion soon after drug initiation. [Case 1] A 38-year-old woman was referred to our hospital because of left wrist joint pain. At the time of examination, swelling and tenderness of the left wrist joint were observed. After 6 months of medication, no improvement in symptoms was noted; therefore, partial wrist fusion was performed. [Case 2] A 38-year-old woman was referred to our hospital because of right wrist joint pain. A plain X-ray image showed fusion of the carpal bones. Due to previous failure of drug treatment, the patient opted for arthrodesis. The postoperative course was good in both cases, and the pain improved. In these cases of monoarthritic RA, synovitis and bone destruction were observed, but blood tests showed no features of active disease, and drug treatment was ineffective. In such cases, early surgical treatment should be considered, rather than continuing conservative treatment, to ensure the best outcomes.

Consideration of differences in drug usage between young-onset and elderly-onset rheumatoid arthritis with target of low disease activity

OBJECTIVES

Elderly-onset rheumatoid arthritis (EORA) is reported to differ from young-onset rheumatoid arthritis (YORA) with regard to patient background and drug treatment. We examined the amount of drug administered to patients who achieved low disease activity (LDA) for rheumatoid arthritis at our hospital.

METHODS

Demographics, clinical history, and treatments were compared between patients with EORA (n = 70) and YORA (n = 190).

RESULTS

There was a significant difference in the average age (73.8 vs. 57.8 years), disease duration (6.66 vs. 14.7 years), and sex (62.9% males vs. 83.7% females), but no difference in rheumatoid factor positivity (85.3% vs. 80.7%), anti-citrullinated peptide antibody positivity (86.5% vs. 87.7%), simplified disease activity index (4.28 vs. 4.59), or disease activity score 28-CRP (1.99 vs. 2.04) in the EORA and YORA groups, respectively. There were also no significant differences in prednisolone use (37.1% vs. 36.3%), amount of methotrexate administered (MTX) (1.45 vs. 1.41 mg), and MTX use (55.7% vs. 65.3%). However, the MTX dose (2.89 vs. 4.09 mg/week, p = .011) and overall biologics use (32.9% vs. 56.3%, p = .0012) were significantly lower in patients with EORA than in those with YORA.

CONCLUSION

Patients with EORA may be able to achieve LDA with lower drug dosage than those with YORA.

Effects of malalignment and disease activity on osteophyte formation in knees of rheumatoid arthritis patients

PURPOSE

Rheumatoid arthritis (RA) patients with secondary osteoarthritis (OA) in a knee joint following a total knee arthroplasty (TKA) procedure have been increasing. Here, we investigated osteophyte formation in knee joints of RA patients and associated factors.

METHODS

We retrospectively examined findings of 35 knees in 30 RA patients (26 females, 4 males; mean age: 63.0 years; median disease duration: 15 years) who underwent TKA, including preoperative anteroposterior view radiographs of the knee joint. Using the ImageJ software package, osteophyte size in the medial femur (MF), medial tibia (MT), lateral femur (LF), and lateral tibia (LT) regions was also determined.

RESULTS

The mean femorotibial angle was 179°, while Larsen grade was 2 in 1, 3 in 12, 4 in 18, and 5 in 2 patients. Osteophyte sizes in the MF, MT, LF, and LT regions were 37.2, 17.0, 27.2, and 4.57 mm², respectively, and significantly greater in the medial compartment (MC; MF+MT) than the lateral compartment (LC; LF+LT) (p < 0.001). In varus cases, osteophyte size in the MC was significantly larger than normal and valgus cases (p = 0.0016). Furthermore, osteophyte size in the MC was negatively correlated with the inflammatory markers C-reactive protein (r = -0.492, p = 0.0027) and erythrocyte sedimentation rate (r = -0.529, p = 0.0016), whereas that in the LC was negatively correlated with disease activity (r = -0.589, p = 0.0023).

CONCLUSION

Our results suggest that alignment and disease activity influence osteophyte formation in RA patients, with secondary OA a more prominent symptom in RA patients with controlled inflammation.

Impact of higher detection rate of residual pulmonary thromboemboli one-year after acute pulmonary embolism: modified CT scan imaging method with modified CT obstruction index

Background

Recently, post pulmonary embolism (PE) syndrome or chronic thromboembolic disease after acute PE, has been recognized as important long-term complications. Furthermore, patients may develop with chronic thromboembolic pulmonary hypertension.

Purpose

We aimed to evaluate the frequency of residual pulmonary thromboemboli after acute PE by using our “higher”-resolution CT scan imaging method to detect residual thromboemboli down to sub-segmental pulmonary arteries.

Methods

This study was a prospective multi-center observational study. We enrolled consecutive 34 patients with acute symptomatic PE whose informed consent was obtained, and followed up for one year. One year after the onset of acute PE, patients were referred to our hospital and multiple examination including CT scan, 6-minute walk test (6MWT), questionnaire of SF-36, echocardiography and laboratory testing were performed. Additionally, we have modified the CT obstruction index (CTOI) to quantitatively evaluate the thromboemboli down to sub-segmental pulmonary arteries.

Results

Mean age was 60.5±15.8 years, and 56% were male. No patient was categorized as low recurrent VTE risk which was caused by transient factors, one patient was associated with active cancer, and 12% had known thrombophilia. In 85% of the patients, this onset was the first obvious episode of PE. At diagnosis, elevated B-type natriuretic peptide (BNP) (≥100 pg/ml) or N-terminal (NT)-proBNP (≥500 pg/ml) was observed in 45% of the patients. Median tricuspid regurgitation peak gradient (TRPG) by echocardiography was 30.9 (19.3–50.1) mmHg. Among all, 35% of the patients received single-drug approach with DOACs. At discharge, all of the patients except two were treated with DOACs.

One year after the onset, 21% of the patient were in NYHA II and others were in NYHA I. It was notable that pulmonary thromboemboli was detected by our CT scan in 76% of the patients. Modified CTOI was median 11.9 (1.8–24.4) % as shown in the figure.

In multiple regression analysis, TRPG at diagnosis and BNP at one month were significantly associated with mCTOI (β=0.536, p=0.002 and β=−0.482, p=0.003, respectively). Additionally, lowest SpO2 during 6MWT after one year from the onset, tended to inversely associate with mCTOI (β=−0.341, p=0.052).

Conclusions

Using our modified CT scan imaging method and modified CTOI, residual pulmonary thromboemboli was able to be detected more frequently than the previous studies. Residual pulmonary thromboemboli could be one of the cause of the post PE syndrome and lead to exercise-induced desaturation.

Figures

Funding Acknowledgement

Type of funding source: None

Is the ischiofemoral space value of Japanese hip joints equal to that of Western populations?

Ischiofemoral space (IFS) is a radiological parameter employed for diagnosing ischiofemoral impingement (IFI). The mean IFS value measured with the leg in natural resting position has been reported as 23.0 mm in males and 18.6 mm in females in a patients-based Western population. The normal value of IFS for an Asian population is unknown. This study therefore aimed to investigate whether the IFS value in Japanese hip joints equals that of the Western population. We retrospectively examined 89 consecutive Japanese individuals (178 hips) (46 male subjects with 92 hips, 43 female subjects with 86 hips; mean age 58.7 ± 15.7 years, range 17-84 years) who had undergone computed tomography (CT) for conditions unrelated to hip disorders and ordered by other departments at our institution. All CT scans were performed in a standardized fashion: patient in a flat spine position, hips and knees in extension, and the leg in its natural resting position. IFS was evaluated on axial images as the shortest distance between the ischium and the lesser trochanter. The mean IFSs of this Japanese patient-based population were 20.5 ± 7.3 mm [95% confidence interval (CI) 19.0-22.0] in the male cohort and 13.9 ± 6.5 mm (95% CI 12.6-15.3) in the female cohort. The IFS value was significantly smaller in female subjects than in male subjects. Taking the lower limit of 95% CI into consideration, the IFSs measured in natural leg-resting position in the Japanese male and female groups were significantly smaller than those of the Western populations.

Wnt signaling pathway correlates with ossification of the spinal ligament: A microRNA array and immunohistochemical study

BACKGROUND

Ossification of the posterior longitudinal ligament or the ligamentum flavum parallels endochondral ossification. Cell differentiation at the ossification front is known to be important during this process, although the factors regulating its initiation and progression are still unclear. The purpose of this study was to identify factors important for the regulation of chondrocyte/osteoblast differentiation during spinal ossification.

METHODS

Ligamentum flavum tissue was isolated from 25 patients who underwent decompressive surgery for cervical ossification of the posterior longitudinal ligament. Tissue sections were used for in vitro culture to obtain primary cells through migration methods. To identify microRNAs associated with ossification of the posterior longitudinal ligament, cultured cells were prepared from the ligamentous tissue (n = 4; continuous type) or from control ligamentous samples harvested from patients with cervical spondylosis without spinal ossification, and analyzed using a microRNA array. The ligamentous sections were also examined by immunohistochemistry for the expression of candidate microRNA target genes.

RESULTS

The microRNA array identified 177 factors; 12 of which were expressed at significantly different levels in patients with ossification of the posterior longitudinal ligament compared to those in control patients. The hsa-miR-487b-3p was down-regulated in patients with ossification of the posterior longitudinal ligament, which met the false discovery rate of <0.05. This microRNA was predicted to regulate the expression of genes involved in Wnt signaling. Furthermore, immunohistochemistry of Wnt signaling proteins, including Wnt 3a, LRP5/6, and beta-catenin, revealed positive expression in mesenchymal cells and/or premature chondrocytes at the ossification front.

CONCLUSION

Our results suggested that down-regulation of miR-487b-3p plays an important role in the initiation of Wnt signaling during the ossification process. Wnt signaling may regulate both chondrocyte and osteoblast differentiation and the specification of endochondral ossification in the pathogenesis of ossification of the posterior longitudinal ligament or the ligamentum flavum.

Total knee arthroplasty for treatment of osteoarthritis with prolonged patellar dislocation

Prolonged dislocation of the patella is a rare condition and is often related to severe osteoarthritis (OA) of the femorotibial (FT) joint. For this condition's treatment, numerous surgical techniques using total knee arthroplasty (TKA) have been published. To the best of our knowledge, this case report is the first description of the use of lateral release alone to treat recurrent patellar subluxation with TKA. An interesting point in this case is that the patient had a good recovery after TKA in spite of quite a long-term (a duration of almost 55 years) dislocation of her patella and development of secondary OA. We describe a case that we treated by TKA for FT-OA with a prolonged patellar dislocation. We were able to obtain good patellar reduction without additional surgery by performing adequate lateral release of the patellar retinaculum. This clinical case indicates the usefulness of lateral patellar retinaculum release for obtaining stable patellar tracking in TKA for FT-OA with remaining lateral patellar dislocation. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Activation of a chondrocyte volume-sensitive Cl(-) conductance prior to macroscopic cartilage lesion formation in the rabbit knee anterior cruciate ligament transection osteoarthritis model

OBJECTIVE

The anterior cruciate ligament transection (ACLT) rabbit osteoarthritis (OA) model confers permanent knee instability and induces joint degeneration. The degeneration process is complex, but includes chondrocyte apoptosis and OA-like loss of cartilage integrity. Previously, we reported that activation of a volume-sensitive Cl(-) current (ICl,vol) can mediate cell shrinkage and apoptosis in rabbit articular chondrocytes. Our objective was therefore to investigate whether ICl,vol was activated in the early stages of the rabbit ACLT OA model.

DESIGN

Adult Rabbits underwent unilateral ACLT and contralateral arthrotomy (sham) surgery. Rabbits were euthanized at 2 or 4 weeks. Samples were analyzed histologically and with assays of cell volume, apoptosis and electrophysiological characterization of ICl,vol.

RESULTS

At 2 and 4 weeks post ACLT cartilage appeared histologically normal, nevertheless cell swelling and caspase 3/7 activity were both significantly increased compared to sham controls. In cell-volume experiments, exposure of chondrocytes to hypotonic solution led to a greater increase in cell size in ACLT compared to controls. Caspase-3/7 activity, an indicator of apoptosis, was elevated in both ACLT 2wk and 4wk. Whole-cell currents were recorded with patch clamp of chondrocytes in iso-osmotic and hypo-osmotic external solutions under conditions where Na(+), K(+) and Ca(2+) currents were minimized. ACLT treatment resulted in a large increase in hypotonic-activated chloride conductance.

CONCLUSION

Changes in chondrocyte ion channels take place prior to the onset of apparent cartilage loss in the ACLT rabbit model of OA. Further studies are needed to investigate if pharmacological inhibition of ICl,vol decreases progression of OA in animal models.

Wild boars from Sweden, Austria, the Czech Republic and Japan possess intact mannose-binding lectin 2 (MBL2) genes

The two-nucleotide deletion recently detected in the mannose-binding lectin 2 gene in purebred and crossbred domestic pigs was not found among 68 wild boars representing 4 populations from Europe and Asia. This suggests that the deletion is a result of breeding and/or genetic drift/bottle necks.

The COX-2 selective blocker etodolac inhibits TNFα-induced apoptosis in isolated rabbit articular chondrocytes

Chondrocyte apoptosis contributes to the disruption of cartilage integrity in osteoarthritis (OA). Recently, we reported that activation of volume-sensitive Cl⁻ current (I_Cl,vol) mediates cell shrinkage, triggering apoptosis in rabbit articular chondrocytes. A cyclooxygenase (COX) blocker is frequently used for the treatment of OA. In the present study, we examined in vitro effects of selective blockers of COX on the TNFα-induced activation of I_Cl,vol in rabbit chondrocytes using the patch-clamp technique. Exposure of isolated chondrocytes to TNFα resulted in an obvious increase in membrane Cl⁻ conductance. The TNFα-evoked Cl⁻ current exhibited electrophysiological and pharmacological properties similar to those of I_Cl,vol. Pretreatment of cells with selective COX-2 blocker etodolac markedly inhibited I_Cl,vol activation by TNFα as well as subsequent apoptotic events such as apoptotic cell volume decrease (AVD) and elevation of caspase-3/7 activity. In contrast, a COX-1 blocker had no effect on the decrease in cell volume or the increase in caspase-3/7 activity induced by TNFα. Thus, the COX-2-selective blocker had an inhibitory effect on TNFα-induced apoptotic events, which suggests that this drug would have efficacy for the treatment of OA.

17β-Oestradiol inhibits doxorubicin-induced apoptosis via block of the volume-sensitive Cl(-) current in rabbit articular chondrocytes

BACKGROUND AND PURPOSE Chondrocyte apoptosis contributes to disruption of cartilage integrity in osteoarthritis. Recent evidence suggested that the volume-sensitive organic osmolyte/anion channel [volume-sensitive (outwardly rectifying) Cl(-) current (I(Cl,vol) )] plays a functional role in the development of cell shrinkage associated with apoptosis (apoptotic volume decrease) in several cell types. In this study, we investigated the cellular effects of 17β-oestradiol on doxorubicin-induced apoptotic responses in rabbit articular chondrocytes. EXPERIMENTAL APPROACH Whole-cell membrane currents and cross-sectional area were measured from chondrocytes using a patch-clamp method and microscopic cell imaging, respectively. Caspase-3/7 activity was assayed as an index of apoptosis. KEY RESULTS Addition of doxorubicin (1 µM) to isosmotic bath solution rapidly activated the Cl(-) current with properties similar to those of I(Cl,vol) in chondrocytes. Doxorubicin also gradually decreased the cross-sectional area of chondrocytes, followed by enhanced caspase-3/7 activity; both of these responses were totally abolished by the I(Cl,vol) blocker DCPIB (20 µM). Pretreatment of chondrocytes with 17β-oestradiol (1 nM) for short (approximately 10 min) and long (24 h) periods almost completely prevented the doxorubicin-induced activation of I(Cl,vol) and subsequent elevation of caspase-3/7 activity. These effects of 17β-oestradiol were significantly attenuated by the oestrogen receptor blocker ICI 182780 (10 µM), as well as the phosphatidyl inositol-3-kinase (PI3K) inhibitors wortmannin (100 nM) and LY294002 (20 µM). Testosterone (10 nM) had no effect on the doxorubicin-induced Cl(-) current. CONCLUSIONS AND IMPLICATIONS 17β-Oestradiol prevents the doxorubicin-induced cell shrinkage mediated through activation of I(Cl,vol) and subsequent induction of apoptosis signals, through a membrane receptor-dependent PI3K pathway in rabbit articular chondrocytes.

MBL1 genotypes in wild boar populations from Sweden, Austria, the Czech Republic, and Japan

The single nucleotide polymorphism (SNP) G949T in the mannose-binding lectin ( MBL ) 1 gene has been associated with low MBL-A concentration in serum and detected at different frequencies in various European pig populations. However, the origin of this SNP is not known. Part of the MBL1 gene was sequenced in 12 wild boar/Large White crossbred pigs from the second backcross (BC 2 ) generation in a family material originating from two wild boar x Large White intercrosses. Also, MBL-A serum concentration was measured in the entire BC 2 generation (n = 45). Furthermore, the genotypes of 68 wild boars from Sweden, Austria, the Czech Republic, and Japan were determined in regard to five previously described SNPs in MBL1 . The T allele of G949T was present among the BC 2 animals. MBL-A serum concentration in the BC 2 animals showed a bimodal distribution, with one-third of the animals at levels between 0.7 and 1.6 μg mL(-1) and the remaining pigs at levels around 13 μg mL(-1) . There was a co-variation between the presence of the T allele and low MBL-A concentration in serum. The genotyping of the wild boars revealed differences between populations. The T allele of G949T was not detected in the Austrian and Japanese samples and is thus unlikely to be an original feature of wild boars. In contrast, it was present at high frequency (0.35) among the Swedish wild boars, probably representing a founder effect. Five MBL1 haplotypes were resolved. Only two of these were present among the Japanese wild boars compared to four in each of the European populations. This difference may reflect differences in selection pressure and population history.

Worldwide genetic relationships of pigs as inferred from X chromosome SNPs

The phylogeography of the porcine X chromosome has not been studied despite the unique characteristics of this chromosome. Here, we genotyped 59 single nucleotide polymorphisms (SNPs) in 312 pigs from around the world, representing 39 domestic breeds and wild boars in 30 countries. Overall, widespread commercial breeds showed the highest heterozygosity values, followed by African and American populations. Structuring, as inferred from FST and analysis of molecular variance, was consistently larger in the non-pseudoautosomal (NPAR) than in the pseudoautosomal regions (PAR). Our results show that genetic relationships between populations can vary widely between the NPAR and the PAR, underscoring the fact that their genetic trajectories can be quite different. NPAR showed an increased commercial-like genetic component relative to the PAR, probably because human selection processes to obtain individuals with high productive parameters were mediated by introgressing boars rather than sows.

Spatiotemporal control of proliferation and differentiation of bone marrow-derived mesenchymal stem cells recruited using collagen hydrogel for repair of articular cartilage defects

Articular cartilage has a poor healing capacity, and cartilage regeneration is not always warranted to achieve healing. On the other hand, collagen scaffolds have been shown to support regeneration of articular cartilage defects in animal models, whereas bone morphogenetic protein-2 (BMP-2) is known to cause chondrogenic differentiation of marrow-derived mesenchymal stem cells (MSCs). The purpose of this study was to evaluate the effectiveness of intra-articular administration of BMP-2 into bone marrow-derived MSCs recruited to defects using original collagen hydrogel in rabbits at various time points. Full-thickness defects were created in both knees, then collagen hydrogels were transplanted, and BMP-2 was supplied for 1-week periods, as follows. BMP-2 was administered immediately after the operation for 1 week (BMP0-1 group), and BMP-2 was administered between weeks 1 and 2 after the operation (BMP1-2 group). BMP2 was administered between weeks 2 and 3 (BMP2-3 group). Specimens were then obtained, and bromodeoxyuridine (BrdU)-positive cells were enumerated and histologic grading was also performed. In addition, the gene expression analysis was performed using quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) assays. Enumeration of BrdU-positive cells showed a significant increase in the BMP0-1 group compared with the other groups. Similarly, histologic scores in the BMP0-1 group were superior for up to 8 weeks. Finally, RT-PCR findings revealed that immediate BMP-2 administration enhanced chondrogenic differentiation.

Identification of N-homocysteinylated apolipoprotein AI in normal human serum

Background

In human serum, a portion of homocysteine (Hcy) exists as an N-linked form to the ε-amino group of protein lysine residues. N-homocysteinylated proteins differ structurally and functionally from native proteins. The present study strives to develop detection and potential semi-quantification methods for N-homocysteinylated apolipoprotein AI ( N-Hcy-apoAI) in human serum.

Methods

Serum treated with or without cysteamine was supplied to isoelectric focusing (IEF) followed by an immunoblot using an anti-apoAI antibody. Cysteamine treatment increased the isoelectric point for N-Hcy-apoAI, but not for unmodified apoAI, due to the presence of -SH group(s) derived from Hcy and the absence of a cysteine residue in the apoAI molecule. N-Hcy-apoAI was semi-quantified from the scanned immunoblot pattern via a computer.

Results

After cysteamine treatment, N-Hcy-apoAI in the serum was identified by IEF at the position with a higher pI value compared with intact apoAI. The reproducibility (between assays) of the semi-quantification method was 19.1% CV (coefficient of variation) for an average ratio 5.9% of N-Hcy-apoAI to the whole apoAI in the serum. Approximately 1.0–7.4% of apoAI was N-homocysteinylated in the serum obtained from 27 healthy subjects. Neither the ratio of N-Hcy-apoAI nor its concentration, calculated by total apoAI concentration, indicated correlation with the so-called total (free and S-linked) Hcy concentration.

Conclusions

We directly found that a portion of apoAI in the serum undergoes homocysteinylation in an N-linkage manner, and used this to develop a potential semi-quantification method for N-Hcy-apoAI.

Regulatory role of tyrosine phosphorylation in the swelling-activated chloride current in isolated rabbit articular chondrocytes

Articular chondrocytes are exposed in vivo to the continually changing osmotic environment and thus require volume regulatory mechanisms. The present study was designed to investigate (i) the functional role of the swelling-activated Cl(-) current (I(Cl,swell)) in the regulatory volume decrease (RVD) and (ii) the regulatory role of tyrosine phosphorylation in I(Cl,swell), in isolated rabbit articular chondrocytes. Whole-cell membrane currents were recorded from chondrocytes in isosmotic, hyposmotic and hyperosmotic external solutions under conditions where Na(+), K(+) and Ca(2+) currents were minimized. The cell surface area was also measured using microscope images from a separate set of chondrocytes and was used as an index of cell volume. The isolated chondrocytes exhibited a RVD during sustained exposure to hyposmotic solution, which was mostly inhibited by the I(Cl,swell) blocker 4-(2-butyl-6,7-dichloro-2-cyclopentyl-indan-1-on-5-yl)oxobutyric acid (DCPIB) at 20 microM. Exposure to a hyposmotic solution activated I(Cl,swell), which was also largely inhibited by 20 microM DCPIB. I(Cl,swell) in rabbit articular chondrocytes had a relative taurine permeability (P(tau)/P(Cl)) of 0.21. Activation of I(Cl,swell) was significantly reduced by the protein tyrosine kinase (PTK) inhibitor genistein (30 microM) but was only weakly affected by its inactive analogue daidzein (30 microM). Intracellular application of protein tyrosine phosphatase (PTP) inhibitor sodium orthovanadate (250 and 500 microM) resulted in a gradual activation of a Cl(-) current even in isosmotic solutions. This Cl(-) current was almost completely inhibited by 4,4-diisothiocyanatostilbene-2,2-disulfonate (DIDS, 500 microM) and was also largely suppressed by exposure to hyperosmotic solution, thus indicating a close similarity to I(Cl,swell). Pretreatment of chondrocytes with genistein significantly prevented the activation of the Cl(-) current by sodium orthovanadate, suggesting that the basal activity of endogenous PTK is required for the activation of this Cl(-) current. Our results provide evidence to indicate that activation of I(Cl,swell) is involved in RVD in isolated rabbit articular chondrocytes and is facilitated by tyrosine phosphorylation.

Evolution of a pairing-induced pseudogap from the superconducting gap of (Bi,Pb)2Sr2CuO6

We have performed an ultrahigh-resolution angle-resolved photoemission spectroscopy study of slightly overdoped (Bi,Pb)2Sr2CuO6 to elucidate the origin of the pseudogap. By using a newly developed xenon-plasma light source, we determined the comprehensive momentum and temperature dependencies of the superconducting gap and the pseudogap. We found that the antinodal pseudogap persists far above the superconducting transition temperature and is smoothly connected to the nodal gap. The characteristic temperature of the pseudogap scales well with the superconducting gap size irrespective of the momentum location. The present experimental results point to the pairing origin of the pseudogap.

Primary chylopericardium with pulmonary lymphedema

Primary chylopericardium is an uncommon entity, and its association with pulmonary lymphedema has been rarely reported.We describe a case of primary chylopericardium with pulmonary lymphedema developing into hypoxemia. The pulmonary lesions were histologically diagnosed as pulmonary lymphangiectasis and lymphedema on lung biopsies. Lymphedema seems to suggest the existence of chylous reflux with pulmonary lymphangiectasis. The patient underwent pericardial fenestration and resection of the thoracic duct. After the operation, the chylous accumulation in the pericardial cavity had disappeared,and hypoxemia improved following the disappearance of the pulmonary lesions.

A novel exogenous concentration-gradient collagen scaffold augments full-thickness articular cartilage repair

OBJECTIVES

A collagen scaffold has been long used in order to enhance the regeneration of articular cartilage. In the present study, we investigate the effectiveness of a concentration-gradient (CG) collagen that is designed to recruit efficiently the mesenchymal stem cells (MSCs) to the central region of the full-thickness cartilage defects via haptotaxis.

METHODS

The present study used Cellmatrix (0.3% type I collagen; Nitta gelatin, Osaka, Japan) as the collagen material. We prepared 33%CG collagen gel and 50%CG collagen gel. No gradient collagen gel served as negative control. Full-thickness cartilage defects were created at the patella groove of the rabbit knee, to which the three different collagen gels were transplanted. Bromodeoxyuridine (BrdU) positive, proliferating cells were enumerated and localized, whereas the histological grading score for cartilage regeneration was counted. The expression of type I and type II collagens was evaluated by immunohistochemistry. We also confirmed that the MSCs migrate toward the collagen substrate of higher concentration in a stringently in vitro haptotactic manner.

RESULTS

Enumeration of the BrdU-positive cells demonstrated that 33%CG collagen gel recruited a significantly larger number of proliferating cells to the central region of the cartilage defect. The histological grading score for the regenerated cartilage treated with 33%CG collagen gel was superior to the other groups.

CONCLUSIONS

CG collagen scaffold recruits effectively the MSCs to the center of full-thickness cartilage defect and enhances regeneration of the full-thickness cartilage defect.