Dual function of β-catenin in articular cartilage growth and degeneration at different stages of postnatal cartilage development

PURPOSE

The objective of this study was to determine the role of β-catenin in normal postnatal articular cartilage growth and degeneration.

METHODS

We investigated β-catenin gene and protein expression in hip cartilage cells of normal Wistar rats at two, four, six and eight weeks of age by using reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry. Primary articular chondrocytes from eight week old rats were cultured and treated with LiCl for activation of β-catenin. Collagen X and matrix metalloproteinase 13 (MMP-13) were detected by quantitative RT-PCR and immunofluorescence. A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-4 and 5 were detected by quantitative RT-PCR, and terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) was used for detecting cell apoptosis.

RESULTS

The highest levels of β-catenin expressions were detected in two week old rats, after which a steady decline was observed over the remaining period of observation (p < 0.05). When primary articular chondrocytes from eight week old rats were treated with LiCl, β-catenin mRNA and protein were induced (p < 0.05). Moreover, LiCl-activated β-catenin in chondrocytes was associated with significant concomitant increases in mRNA expression of collagen X and the MMP-13 encoding collagenase 3. Significantly increased mRNA expression of ADAMTS-5 was also seen in primary chondrocytes from eight week old rats after LiCl treatment (p < 0.05). The effect was specific to ADAMTS-5 since ADAMTS-4, which has similar proteolytic activity but different aggrecanase activity, was unaffected. Finally, TUNEL staining revealed that LiCl-activated β-catenin signalling led to increased cell apoptotic events in chondrocytes (p < 0.05).

CONCLUSIONS

Our findings suggest that normal spatiotemporal patterns and degrees of Wnt/β-catenin signalling are needed to maintain postnatal articular cartilage growth and function. In the early stages of cartilage development, activation of β-catenin signalling is necessary for articular cartilage growth, while in adult cartilage it leads to degeneration and osteoarthritic-like chondrocytes.

Correlation between expression of cadherin and gap junctional communication in human lung carcinoma cells

The correlation between expression of ca(2+)-dependent cell adhesion molecule, cadherin, and gap junctional intercellular communication (GJIC) in human lung carcinoma PG cell line and connexin43 (Cx43) cDNA transfected PG cell clones was investigated. Results from immunoblotting and immunofluorescent staining revealed that cultured normal human lung cells (RF) expressed N-cadherin. However, the expression level of Kcadherin in PG cells was very low in comparison with normal RF cells. The Cx43 transfected PG clones exhibited comparable levels of Cx43 protein, but varied in the level of N-cadherin expression and in the function of GJIC as measured by scrape-loading and dye transfer (SLDT) method. Positive correlation between N-cadherin and GJIC was demonstrated. Thein vitro andin uivo, growth examination results suggest that N-cadherin mediated cell-cell adhesions and Cx43 functional expression, the GJIC, may work coordinately with each other in regulation of cell growth and differentiation. Deficiency in both GJIC and cell adhesion may be crucial for cell transformation.

Continuous production and recovery of recombinant Ca2+ binding receptor from HEK 293 cells using perfusion through a packed bed bioreactor

The extracellular domain of human parathyroid Ca(2+) receptor was needed in order to study itsstructure and clinical application. The Ca(2+)receptor is a unique member of the G protein-coupledreceptor super-family, expressed in parathyroid andkidney cells where it has been shown to play acritical role in extracellular calcium homeostasis.The desired protein was produced by immobilizing thetransformed HEK 293 cells in a packed-bedconfiguration using a 1.6 l (working volume)bioreactor equipped with a vertical mixing impellerassembly and an internal basket. The process includeda propagation phase followed by a production phase. Inthe propagation phase, lasting approximately 160 h, the bed was perfused with a serum-containingmedium, allowing the cells to grow at a constantgrowth rate to approximately 3 x 10(10). At this point the production phase was begun, replacing themedium with serum-free medium and continuing theperfusion process for additional 350 h. Duringthis phase, the medium was pumped through the packedbed at a rate of 4-6 l per day, keeping theresidual glucose concentration around 1 g l(-1) andcollecting and processing approximately 80 l ofspent medium. This continuous perfusion method of thepacked-bed bioreactor was compared to a repeated batchmethod in which existing medium was replenished whenthe glucose concentration was down to 1 g l(-1). Using this method, serum-free medium was replaced withserum containing medium a few times when a decline inthe glucose consumption was observed. Though mediumconsumption and protein yield are similar in bothmethods (roughly 10 mg l(-1)), there aredifferences related to the ease of operation andprocessing of the produced protein. The continuousperfusion operation was found to be preferable and waschosen as the production strategy.

In vitro study of enhanced osteogenesis induced by HIF-1α-transduced bone marrow stem cells

OBJECTIVES

Hypoxia-inducible factor 1α (HIF-1α) is a pivotal regulator of hypoxic and ischaemic vascular responses that drives transcriptional activation of hundreds of genes involved in vascular reactivity, angiogenesis and arteriogenesis. Previous reports based on gene knockout technology have demonstrated that HIF-1α can promote osteogenesis. However, this protein is easily degraded in a normoxic state, which makes in vitro studies of HIF-1α-induced mesenchymal stem cell (MSC) osteogenesis difficult. For better understanding of HIF-1α promoting osteogenesis, the role of HIF-1α-induced MSC osteogenesis in the normoxic state has been investigated here.

MATERIALS AND METHODS

HIF-1α was made to overexpress using a lentiviral vector, and its effects on bone marrow-derived mesenchymal stem cell (BMSC) osteogenesis were investigated. Real-time quantitative and western blotting (to assess expression levels of angiogenic and osteogenic related genes regulated by Lenti-HIF-1α), alkaline phosphatase (ALP) and alizarin red-S staining analyses, were performed.

RESULTS

In HIF-1α gene-transfected BMSCs, expression levels of angiogenic, cartilaginous and osteogenic genes were all increased significantly compared to Lenti LacZ-transfected cells, at both mRNA and protein levels. ALP activity and alizarin red-S staining were significantly enhanced in HIF-1α transduced cells compared to control cells, on day 21.

CONCLUSIONS

These results indicate that Lenti-HIF-1α can induce BMSC overexpression levels of angiogenic and osteogenic genes in vitro in the normoxic state. Further study will be focused on whether HIF-1α can also improve bone repair in vivo.

Characterization of 236 novel alleles at the HLA-A, -B, -C, -DRB1, -DQB1 and -DPB1 loci from China Marrow Donor Program

Two hundred and thirty-six novel human leukocyte antigen (HLA) alleles are described from volunteer donors of the China Marrow Donor Program: 71 HLA-A alleles, 79 HLA-B alleles, 43 HLA-C, 16 HLA-DRB1 alleles, 26 HLA-DQB1 and 1 HLA-DPB1. Two hundred and thirteen (90.3%) of the 236 novel alleles are single nucleotide substitution variants when compared with their most homologous allele. Seventy-eight of these single nucleotide variants are silent substitutions. The remaining novel alleles differ from their most similar allele by two to four nucleotide substitutions. Some of the novel alleles encode amino acid changes at positions not previously reported to be polymorphic, such as codons 57, 62, 67, 41 and 52 in HLA-A alleles; codons 133, 156, 201 and 215 in HLA-B alleles; codons 74, 208 and 225 in HLA-C; codons 25, 32 and 72 in HLA-DRB1; codons 20, 39 and 77 in HLA-DQB1.

MiR-200b and miR-15b regulate chemotherapy-induced epithelial-mesenchymal transition in human tongue cancer cells by targeting BMI1

Chemotherapy has been reported to induce epithelial-mesenchymal transition (EMT) in tumor cells, which is a critical step in the process of metastasis leading to cancer spreading and treatment failure. However, the underlying mechanisms of chemotherapy-induced EMT remain unclear, and the involvement of microRNAs (miRNA) in this process is poorly understood. To address these questions, we established stable chemotherapy-resistant tongue squamous cell carcinoma (TSCC) cell lines CAL27-res and SCC25-res by exposing the parental CAL27 and SCC25 lines to escalating concentrations of cisplatin for 6 months. CAL27-res and SCC25-res cells displayed mesenchymal features with enhanced invasiveness and motility. MiRNA microarray illustrated that miR-200b and miR-15b were the most significantly downregulated microRNAs in CAL27-res cells. Ectopic expression of miR-200b and miR-15b with miRNA mimics effectively reversed the phenotype of EMT in CAL27-res and SCC25-res cells, and sensitized them to chemotherapy, but inhibition of miR-200b and miR-15b in the sensitive lines with anti-sense oligonucleotides induced EMT and conferred chemoresistance. Retrieving the expression of B lymphoma Mo-MLV insertion region 1 homolog (BMI1), a target for miR-200b and miR-15b, in the presence of the miRNA mimics by transfecting CAL27-res cells with pcDNA3.1-BMI1-carrying mutated seed sequences of miR-200b or miR-15b at its 3'-UTR recapitulated chemotherapy-induced EMT. In vivo, enforced miR-200b or miR-15b expression suppressed metastasis of TSCC xenografts established by CAL27-res cells. Clinically, reduced miR-200b or miR-15b expression was associated with chemotherapeutic resistance in TSCCs and poor patient survival. Our data suggest that reduced expression of miR-200b and miR-15b underscores the mechanisms of chemotherapy-induced EMT in TSCC, and may serve as therapeutic targets to reverse chemotherapy resistance in tongue cancers.

Social consensus through the influence of committed minorities

We show how the prevailing majority opinion in a population can be rapidly reversed by a small fraction p of randomly distributed committed agents who consistently proselytize the opposing opinion and are immune to influence. Specifically, we show that when the committed fraction grows beyond a critical value p(c) ≈ 10%, there is a dramatic decrease in the time T(c) taken for the entire population to adopt the committed opinion. In particular, for complete graphs we show that when p < pc, T(c) ~ exp [α(p)N], whereas for p>p(c), T(c) ~ ln N. We conclude with simulation results for Erdős-Rényi random graphs and scale-free networks which show qualitatively similar behavior.

The protective shell: sclereids and their mechanical function in corollas of some species of Camellia (Theaceae)

Studies of rain-wash effects on pollen have shown that flower structures can protect susceptible pollen from rain. It remains unclear, however, how a thin corolla can withstand external force and perform its protective function. The sclereids in petals of several species of Camellia (Theaceae) were anatomically investigated to determine their mechanical properties. To examine the effects of changing physical environment on the occurrence of sclereids in petals, sclereid density in petals of six species, including wild samples from different rainfall zones and samples from a greenhouse under mild conditions without wind and rain, were examined and statistically analysed. The results showed that the occurrence of sclereids in petals varied with physical environment. The number of sclereids in the same species increased with the increasing rainfall. There were abundant sclereids in petals of the wild species, but few or no sclereids in species cultivated in the greenhouse. Moreover, the anatomical features of sclereids, especially the unique distribution pattern that has not hitherto been described, were correlated with external environmental pressures. Our observations reveal a novel mechanical system in the corolla and provide further evidence for the hypothesis that flower structures may protect rain-susceptible pollen.

Incident knee pain in the Nottingham community: a 12-year retrospective cohort study

OBJECTIVES

To determine the community incidence of knee pain and associated risk factors over a 12-year period in people over the age of 40 years.

METHOD

A cohort study of knee pain was undertaken in 2156 people from four general practices in North Nottinghamshire, UK. Knee pain was defined as 'pain around the knee for most days of at least a month'. Cumulative incidence over 12 years and person-year incidence rate of knee pain were estimated. Survival analysis was undertaken for time to the onset of knee pain. Hazard ratio (HR) and 95% confidence interval (CI) were estimated for relative risk between exposure and non-exposure. Cox regression model was used to adjust for confounding factors.

RESULTS

The 12-year cumulative incidence of knee pain was 34.4% (32% for men and 35% for women), corresponding to an average incidence rate of 32 (31 for men and 34 for women)/1000 person-years. Incident knee pain was associated with female gender (HR 1.27, 95% CI 1.08, 1.49), obesity (1.80; 95% CI 1.37, 2.38), varus (1.68, 95% CI 1.15, 2.47) and valgus (1.83, 95% CI 1.05, 3.20) mal-alignment, and knee injury (2.37, 95% CI 2.98, 2.85).

CONCLUSIONS

For people over age 40, one in three will develop knee pain within 12 years. On average, the risk of knee pain was 32/1000 person-years. This risk is associated with a variety of constitutional and environmental biomechanical insults to the knee. Some of these could be modified to possibly reduce the incidence of the condition.

Occupational risk factors for osteoarthritis of the knee: a meta-analysis

INTRODUCTION

Systematic reviews agree that knee osteoarthritis (OA) is related to occupational activities, but have not quantified the overall risks.

METHODS

Systematic review of observational studies of knee OA and occupation. Job titles, elite sport, heavy work, kneeling, and other activities were included. Relative risk estimate and 95% confidence interval (CI) compared to sedentary work were retrieved or calculated for meta-analysis. Publication bias was examined with Egger tests and heterogeneity was determined with I(2) values and Q tests. Subgroup analysis was performed to examine causes of heterogeneity. A random effects model was performed to combine the data.

RESULTS

Studies of knee OA (n=51), persistent knee pain (n=12) and knee OA progression (n=3) were retrieved. Occupational risks for knee OA were examined in a total of 526,343 subjects in 8 cohort/prospective/longitudinal studies, 25 cross-sectional studies and 18 case control studies. The overall odds ratio (OR) was 1.61 (95% CI 1.45-1.78) with significant heterogeneity (I(2)=83.6%). Study designs showed a positive association between knee OA and occupational activities; cohort (OR 1.38, 95% CI 1.10-1.74), cross-sectional (OR 1.57, 95% CI 1.37-1.81) and case control (OR 1.80, 95% CI 1.48-2.19). Overall there was evidence of publication bias (P<0.0001) which was apparent in the cross-sectional and case control studies (P<0.0001 and P=0.0247 respectively).

CONCLUSIONS

Some occupational activities increase the risk of knee OA, although the influences of publication bias and heterogeneity are important limitations of this study. Prospective studies would greatly improve the evidence base.

The effect of formoterol on airway goblet cell hyperplasia and protein Muc5ac expression in asthmatic mice

OBJECTIVES

Aim for this study was to investigate the effect of long-acting beta2-adrenoceptor agonist formoterol on airway goblet cell hyperplasia and protein Muc5ac expression in asthmatic mice.

MATERIALS AND METHODS

Forty female BABL/c mice were randomly divided into four groups with 10 mice in each. Mice in group A were treated with saline as control, and mice in group B, group C and group D were sensitized by intraperitoneal injection of 10 microg alum precipitated chicken egg ovalbumin (OVA) to establish asthmatic model, but group C were pretreated with formoterol and group D were pretreated with dexamethasone. All mice were killed 24 hours after the final OVA challenging. The left lung tissue sections were stained with periodic acid Schiff (PAS) for identification of goblet cell hyperplasia. Immunohistochemistry was used to identify the protein of Muc5ac. The right lung was isolated for detecting Muc5ac mRNA by the method of real-time fluorescence quantitative reverse transcription Polymerase Chain Reaction (real-time qRT-PCR).

RESULTS

The number of the goblet cells, the percentage of goblet cell to total cell, the transcription and the expression of Muc5ac were significantly higher in group B than those in group A [(163.63 +/- 16.68) vs. (0.46 +/- 0.16), (77.36 +/- 5.05) % vs. (0.03 +/- 0.01) % (10.31 +/- 0.73) vs. (1.00 +/- 0.13), (0.64 +/- 0.03) vs. (0.19 +/- 0.03) respectively, all P < 0.05]. The number of the goblet cells, the percentage of goblet cell to total cell, the transcription and the expression of Muc5ac were significantly lower in group C than those in group B [(52.04 +/- 4.60) vs (163.63 +/- 16.68), (30.05 +/-3.72) % vs. (77.36 +/- 5.05) %, (1.64 +/- 0.14) vs. (10.31 +/- 0.73), (0.26 +/- 0.01) vs (0.64 +/- 0.03) respectively, all P < 0.05] The number of the goblet cells, the percentage of goblet cell to total cell, the transcription and the expression of Muc5ac were significantly lower in group D than those in group B [(63.41 +/- 6.39) vs. (163.63 +/- 16.68), (38.52 +/- 3.83)% vs. (77.36 +/- 5.05) %, (1.72 +/- 0.10) vs. (10.31 +/- 0.73), (0.31 +/- 0.01) vs. (0.64 +/- 0.03) respectively, all P < 0.05]. For mentioned above, no significant differences were found between group C and group D [(52.04 +/- 4.60) vs. (63.41 +/- 6.39), (30.05 +/- 3.72) % vs. (38.52 +/- 3.83) %, (1.64 +/- 0.14) vs. (1.72 +/- 0.10), (0.26 +/- 0.01) vs. (0.31 +/- 0.01) respectively, all P < 0.05].

CONCLUSIONS

This study demonstrates that the long-acting beta2-receptor agonist formoterol may inhibit airway goblet cell hyperplasia and protein Muc5ac expression in asthmatic mice.

Outcomes of post-cataract surgery endophthalmitis referred to a tertiary center from local hospitals in the south of China

BACKGROUND

Endophthalmitis after cataract surgery is an uncommon but devastating complication. Prophylactic intracameral injection of cefuroxime 1 mg at the end of surgery decreases the incidence five-fold. The visual outcome can be good (53% of cases having a visual acuity [VA] of better than 20/40) if treatment is initiated rapidly and follows the Endophthalmitis Vitrectomy Study (EVS) guidelines; but even with the best treatment, some patients end up with a poor visual outcome. Previous studies on postoperative endophthalmitis mainly focus on the cases performed in metropolitan tertiary hospitals; however, little information is available on the cases performed in local hospitals in rural areas.

METHODS

We retrospectively reviewed the medical records of patients with acute endophthalmitis following cataract surgery, which were performed in local hospitals and later treated at the Zhongshan Ophthalmic Center between 1 January 1998 and 31 December 2009. Details of each case, including the interval from symptoms to presentation, initial treatment in local hospitals, microorganisms isolated, treatment, and visual outcome, were recorded. Cross-tabulations were conducted in order to identify the prognostic factors of final visual outcome.

RESULTS

Forty-six patients referred from 36 local hospitals and later treated at the Zhongshan Ophthalmic Center were reviewed over the audit period. Most of these cases occurred in April. Gram-positive bacteria were the predominant etiology, with fungal infection accounting for 15%. Even though 54% of patients had symptoms within 3 days post-cataract surgery, they did not present to a tertiary center until a mean of 10 days. The main initial treatment in local hospitals is systemic antibiotics, instead of the intravitreal injection of antibiotics. A high proportion of cases (27/46) received immediate pars plana vitrectomy (PPV) in the tertiary center, and the antibiotic used for intravitreal injection was mainly tobramycin. The final visual outcome was poor, with only three cases having a VA ≥20/40.

CONCLUSION

A relatively high rate of fungal endophthalmitis suggests that sterilization patterns in local hospitals should be further revised. A delayed presentation, inappropriate treatment procedures, poor presenting VA, and causative organism virulence may account for the unfavorable visual outcome in this study.

Analysis of the complete cDNA sequences of HLA-DRB1 alleles with group-specific amplification primers in the Chinese Han population

Currently for the majority of HLA-DRB1 alleles the focus has been mainly on exon 2 and complete cDNA sequences of HLA-DRB1 alleles are rare. In this study, we analyzed the complete coding sequences of partial alleles of HLA-DRB1 locus. The cDNA was amplified by polymerase chain reaction using the group-specific primers located in the 5'- and 3'-untranslated regions to obtain the complete coding sequences. The amplification products were sequenced using an ABI BigDye® Terminator Cycle Sequencing kit. The HLA-DRB1 allele phylogenetic tree was analyzed by dnaman software. Full-length cDNA sequences of 22 HLA-DRB1 alleles were obtained in this study. HLA-DRB1*08:09, DRB1 *12:02:01, and DRB1*13:12 alleles were first reported for complete coding sequences. The sequences of exon 1 of HLA-DRB1*04:06:01, DRB1*08:03:02, and DRB1 *14:07:01 were newly presented. The complete coding sequences of HLA-DRB1 *01:01:01, DRB1*03:01:01:01, DRB1*04:01:01, DRB1*04:05:01, DRB1*07:01:01: 01, DRB1*09:01:02, DRB1*10:01:01, DRB1*11:01:01, DRB1*12:01:01, DRB1*13: 01:01, DRB1*13:02:01, DRB1*14:04, DRB1*14:54, DRB1*15:01:01:01, DRB1*15: 02:01, and DRB1*16:02:01 were identical to those previously reported. Forty polymorphic positions in complete coding sequences outside exon 2 of these HLA-DRB1 alleles were confirmed. According to the phylogenetic tree of full-length coding sequence, the HLA-DRB1 allele was classified into seven major allelic lineages. In conclusion, a protocol for HLA-DRB1 cDNA amplification and sequencing was improved and the data may help to determine the polymorphism of coding sequences outside exon 2.

Zinc finger protein A20 overexpression inhibits monocyte homing and protects endothelial cells from injury induced by high glucose

Diabetes mellitus causes vascular lesions and may ultimately lead to atherosclerosis. One of the earliest steps in the development of atherosclerotic lesions is the adhesion of monocytes to endothelial cells of the vessel wall. It is currently unknown whether zinc finger protein A20 is able to protect endothelial cells from injury caused by high levels of glucose and monocyte homing. In our study, adhesion of monocytes to the vessel wall endothelium was detected by measuring the rolling velocity of monocytes along human umbilical vein endothelial cells (HUVECs). Activation of NF-κB was analyzed through Western blot. HUVEC apoptosis was monitored by TUNEL in situ end-labeling and flow cytometry. High glucose concentrations (25 mM) stimulated monocytes, reducing the velocity at which they roll along HUVECs. Stimulation of monocytes with high levels of glucose also induced HUVEC apoptosis. Overexpression of the zinc finger protein A20 inhibited monocyte recruitment, NF-κB activation, P-selectin expression, and HUVEC apoptosis induced by high glucose levels. We conclude that zinc finger protein A20 can protect HUVECs from injury induced by high levels of glucose and potentially could be used to develop treatments against diabetic vascular lesions.

Social influencing and associated random walk models: Asymptotic consensus times on the complete graph

We investigate consensus formation and the asymptotic consensus times in stylized individual- or agent-based models, in which global agreement is achieved through pairwise negotiations with or without a bias. Considering a class of individual-based models on finite complete graphs, we introduce a coarse-graining approach (lumping microscopic variables into macrostates) to analyze the ordering dynamics in an associated random-walk framework. Within this framework, yielding a linear system, we derive general equations for the expected consensus time and the expected time spent in each macro-state. Further, we present the asymptotic solutions of the 2-word naming game and separately discuss its behavior under the influence of an external field and with the introduction of committed agents.