Induction and expansion of human PRRX1+ limb-bud-like mesenchymal cells from pluripotent stem cells.

Current protocols for the differentiation of human pluripotent stem cells (hPSCs) into chondrocytes do not allow for the expansion of intermediate progenitors so as to prospectively assess their chondrogenic potential. Here we report a protocol that leverages PRRX1-tdTomato reporter hPSCs for the selective induction of expandable and ontogenetically defined PRRX1+ limb-bud-like mesenchymal cells under defined xeno-free conditions, and the prospective assessment of the cells' chondrogenic potential via the cell-surface markers CD90, CD140B and CD82. The cells, which proliferated stably and exhibited the potential to undergo chondrogenic differentiation, formed hyaline cartilaginous-like tissue commensurate to their PRRX1-expression levels. Moreover, we show that limb-bud-like mesenchymal cells derived from patient-derived induced hPSCs can be used to identify therapeutic candidates for type II collagenopathy and we developed a method to generate uniformly sized hyaline cartilaginous-like particles by plating the cells on culture dishes coated with spots of a zwitterionic polymer. PRRX1+ limb-bud-like mesenchymal cells could facilitate the mass production of chondrocytes and cartilaginous tissues for applications in drug screening and tissue engineering.

Manufacturers affect clinical results of THA with zirconia heads: a systematic review.

In the 1980s, zirconia was introduced for THA with the expectation of lower polyethylene wear and better clinical results. However, several studies have reported poor survivorship of zirconia-polyethylene THA. We performed a systematic review and meta-analysis of zirconia-polyethylene THA to confirm or refute the theoretical advantages of this combination. Of 163 studies identified by a comprehensive search, seven met our selection criteria. These involved 769 hips of 586 patients with a mean age of 56.8 years and a minimum followup of 60 months (mean, 89.2 months; range, 60-155 months). The consolidated revision rate of zirconia-polyethylene THA at 89.2 months was higher than that of nonzirconia-polyethylene THA by 5% (risk difference, 0.05; 95% confidence interval, 0.02-0.08). Subgroup meta-analysis suggested THAs with zirconia heads from Ceraver had more revision surgery than nonzirconia heads (risk difference, 0.08; 95% confidence interval, 0.03-0.14), whereas zirconia heads from DePuy did not (risk difference, 0.02; 95% confidence interval, -0.01-0.06). The meta-analysis for annual linear polyethylene wear (which did not involve zirconia heads from Ceraver because of insufficient descriptions) showed no difference between zirconia and control groups. Collectively, THAs with high-quality zirconia heads appear to have prosthesis survivorship and polyethylene wear equivalent to those of THAs with traditional materials, but differing quality among zirconia heads could lead to poor survivorship of prostheses.

Description of adults and larvae of Orientelmis parvula (Nomura amp; Baba, 1961) (Coleoptera: Elmidae) with their molecular phylogenetic analysis.

The elmid beetle Orientelmis parvula (Nomura Baba, 1961) is a rare and endangered species in Japan. Mouth parts and genitalia in adults of both sexes and larval morphology are described based on scanning electron microscope observations. The larva of the genus Orientelmis Shepard, 1998 is described for the first time. The systematic position of the genus is discussed based on the morphology and a phylogenetic tree inferred from the mitochondrial COI, and nuclear ArgK and 18S gene sequences. A new key for larvae of known species and genera of Japanese Elmidae is given.

Periodontitis and Porphyromonas gingivalis in preclinical stage of arthritis patients.

PURPOSE: To determine whether the presence of periodontitis (PD) and Porphyromonas gingivalis (Pg) in the subgingival biofilm associates with the development of rheumatoid arthritis (RA) in treatment naïve preclinical stage of arthritis patients. METHODS: We conducted a prospective cohort study of 72 consecutive patients with arthralgia who had never been treated with any anti-rheumatic drugs or glucocorticoids. Periodontal status at baseline was assessed by dentists. PD was defined stringently by the maximal probing depth≧4 mm, or by the classification by the 5th European Workshop in Periodontology (EWP) in 2005 using attachment loss. Up to eight plaque samples were obtained from each patient and the presence of Pg was determined by Taqman PCR. The patients were followed up for 2 years and introduction rate of methotrexate (MTX) treatment on the diagnosis of RA was compared in patients with or without PD or Pg. RESULTS: Patients with PD (probing depth≧4mm) had higher arthritis activity (p = 0.02) and higher risk for future introduction of MTX treatment on the diagnosis of RA during the follow up than patients without PD (Hazard ratio 2.68, p = 0.03). Arthritis activity and risk for MTX introduction increased with the severity of PD assessed by EWP, although not statistically significant. On the other hand, presence of Pg was not associated with arthritis activity (p = 0.72) or the risk for MTX introduction (p = 0.45). CONCLUSION: In treatment naïve arthralgia patients, PD, but not the presence of Pg, associates with arthritis activity and future requirement of MTX treatment on the diagnosis of RA.

Reduction of atlantoaxial subluxation causes airway stenosis.

STUDY DESIGN: A cross-sectional study. OBJECTIVE: The purpose of this study was to investigate the effect of reduction of anterior atlantoaxial subluxation (AAS) on the oropharyngeal airway space. SUMMARY OF BACKGROUND DATA: Our previous studies have shown that reduction of the occipito-C2 angle (O-C2A) makes the mandible shift posteriorly, resulting in oropharyngeal airway stenosis, which occasionally causes postoperative dysphagia after occipitocervical fusion. Based on this background, we hypothesized that reduction of AAS would also cause oropharyngeal airway stenosis independent of the O-C2A, because it also shifts the mandible posteriorly. To our knowledge, there are no data demonstrating an association between reduction of AAS and the oropharyngeal airway space. METHODS: The authors prospectively evaluated 64 patients with rheumatoid arthritis. We analyzed lateral cervical plain radiographs of 5 different positions (neutral, flexion, extension, retraction, and protrusion), and measured the O-C2A, C2-C6 angle, anterior atlantodental interval, anteroposterior distance of the narrowest oropharyngeal airway space (nPAS), and so on. The subjects were classified into 2 groups: group R comprised patients with a "reducible AAS" in dynamic cervical movement, and group N comprised "patients without AAS" patients. RESULTS: In the multiple regression analysis, the change in the O-C2A was the only significant independent variable related to the percentage change in the nPAS from the neutral position in group N. On the contrary, the change in the anterior atlantodental interval and change in the O-C2A were significantly related to the percentage change in the nPAS in group R. No cases in group N and 7 cases (28%) in group R showed a paradoxical decrease in the nPAS in extension, in which the O-C2A is largest and reduction of AAS is obtained. CONCLUSION: Reduction of AAS has a negative effect on the oropharyngeal airway space. Therefore, reduction of AAS during occipitocervical fusion may cause postoperative dysphagia despite maintenance of the O-C2A.

Atlantoaxial transarticular screw fixation with posterior wiring using polyethylene cable: facet fusion despite posterior graft resorption in rheumatoid patients.

STUDY DESIGN: A comparative retrospective study on the posterior graft union and the facet fusion in atlantoaxial transarticular screw fixation. OBJECTIVE: To evaluate the posterior graft union and the facet fusion in atlantoaxial transarticular screw fixation when a polyethylene (PE) cable was used in rheumatoid and nonrheumatoid patients. SUMMARY OF BACKGROUND DATA: In atlantoaxial transarticular screw fixation, metal wires or cables for posterior bone graft fixation can cause intraoperative or delayed spinal cord compression. PE cables do not have the risk, but there has been no comparative report. Also, a precise evaluation on the posterior graft union and the facet fusion has not been reported. METHODS: Thirty-eight patients who submitted to atlantoaxial transarticular screw fixation and posterior bone graft without any concomitant operation were followed up for more than 2 years. The posterior graft union and the facet fusion were evaluated by functional radiographs and computed tomography scans. RESULTS: Seven patients showed the posterior graft nonunion. All of them were rheumatoid patients and received PE cable wiring for posterior internal fixation. However, 5 of the 7 cases presented stable C1-C2 with the facet fusion demonstrated by functional radiographs and computed tomography scans, achieving an overall fusion rate of 95%. CONCLUSION: In atlantoaxial transarticular screw fixation, the use of PE cable and rheumatoid background are 2 of the unfavorable factors for the posterior graft union. However, atlantoaxial transarticular screws can bring the facet fusion despite the posterior graft failure in such cases.