Einar Andreas Sivertsen

Characterization of early stages of human B cell development by gene expression profiling.

We have characterized several stages of normal human B cell development in adult bone marrow by gene expression profiling of hemopoietic stem cells, early B (E-B), pro-B, pre-B, and immature B cells, using RNA amplification and Lymphochip cDNA microarrays (n = 6). Hierarchical clustering of 758 differentially expressed genes clearly separated the five populations. We used gene sets to investigate the functional assignment of the differentially expressed genes. Genes involved in VDJ recombination as well as B lineage-associated transcription factors (TCF3 (E2A), EBF, BCL11A, and PAX5) were turned on in E-B cells, before acquisition of CD19. Several transcription factors with unknown roles in B lymphoid cells demonstrated interesting expression patterns, including ZCCHC7 and ZHX2. Compared with hemopoietic stem cells and pro-B cells, E-B cells had increased expression of 18 genes, and these included IGJ, IL1RAP, BCL2, and CD62L. In addition, E-B cells expressed T/NK lineage and myeloid-associated genes including CD2, NOTCH1, CD99, PECAM1, TNFSF13B, and MPO. Expression of key genes was confirmed at the protein level by FACS analysis. Several of these Ags were heterogeneously expressed, providing a basis for further subdivision of E-B cells. Altogether, these results provide new information regarding expression of genes in early stages of human B cell development.

Effect of Meniscal and Focal Cartilage Lesions on Patient-Reported Outcome After Anterior Cruciate Ligament Reconstruction A Nationwide Cohort Study From Norway and Sweden of 8476 Patients With 2-Year Follow-up

Background: The effect of concomitant intra-articular injury on patient-reported outcome after anterior cruciate ligament (ACL) reconstruction is debated. Purpose: To evaluate the effect of meniscal and articular cartilage lesions on patient-reported outcome 2 years after ACL reconstruction. Study Design: Cohort study (prognosis); Level of evidence, 2. Methods: The study included all patients with primary, unilateral ACL reconstruction registered in the Norwegian and the Swedish National Knee Ligament Registry from 2005 through 2008 who had completed the Knee Injury and Osteoarthritis Outcome Score (KOOS) Knee-Related Quality of Life subscale at a 2-year follow-up (mean ± SD, 2.1 ± 0.2 years) after surgery (n = 8476). Multiple linear regression analyses were used to evaluate the associations between each KOOS subscale (Pain, Other Symptoms, Activities of Daily Living, Sport and Recreation Function, Knee-Related Quality of Life) as the measure for patient-reported outcome and meniscal and cartilage lesions. Results: A total of 3674 (43%) patients had meniscal lesion(s), 1671 (20%) had partial-thickness (International Cartilage Repair Society [ICRS] grades 1-2) cartilage lesion(s), and 551 (7%) had full-thickness (ICRS grades 3-4) cartilage lesion(s). Multiple linear regression analyses detected no significant associations between meniscal lesions or partial-thickness cartilage lesions and the scores in any of the KOOS subscales at the 2-year follow-up. Full-thickness cartilage lesions were significantly associated with decreased scores in all of the KOOS subscales. Conclusion: Patients with concomitant full-thickness cartilage lesions reported worse outcome in all of the KOOS subscales compared with patients without cartilage lesions 2 years after ACL reconstruction. Meniscal lesions and partial-thickness cartilage lesions did not impair patient-reported outcome 2 years after ACL reconstruction.

Fractures in Children: Epidemiology and Activity-specific Fracture Rates

BACKGROUND Approximately one-third of pediatric fractures occur during sport or recreational activity. In this paper, we investigate the incidence and causes of pediatric fractures in our region and quantify the fracture rate per exposure time for the most common sport and recreational activities. METHODS We prospectively evaluated all children younger than sixteen years who presented to our institution with a new fracture within a twelve-month period. Exposure time to the most common childhood activities was measured by means of interviewing random parents from the study population. The main outcome measures were the annual fracture incidence in the population and fracture rates per 10,000 hours of exposure to various sports and recreational activities. RESULTS A total of 1403 fractures were included. The overall annual incidence was 180.1 fractures per 10,000 children younger than sixteen years. The distal part of the radius was most often fractured (436 fractures, 31.1%). Snowboarding was associated with the highest activity-specific fracture rate, estimated to be 1.9 (95% confidence interval [CI], 1.16 to 2.60) fractures per 10,000 hours of exposure. In comparison, the fracture rate per 10,000 hours of exposure was 0.79 (CI, 0.42 to 1.09) for handball, 0.44 (CI, 0.35 to 0.52) for soccer, and 0.35 (CI, 0.23 to 0.47) for trampolining. CONCLUSIONS The distal part of the radius is the most common fracture site in childhood. Fracture rates differ between various physical activities. The fracture rate for snowboarding was four times higher compared with that for other common childhood sport and recreational activities in our region.

BMP-6 inhibits growth of mature human B cells; induction of Smad phosphorylation and upregulation of Id1

BackgroundBone morphogenetic proteins (BMPs) belong to the TGF-β superfamily and are secreted proteins with pleiotropic roles in many different cell types. A potential role of BMP-6 in the immune system has been implied by various studies of malignant and rheumatoid diseases. In the present study, we explored the role of BMP-6 in normal human peripheral blood B cells.ResultsThe B cells were found to express BMP type I and type II receptors and BMP-6 rapidly induced phosphorylation of Smad1/5/8. Furthermore, Smad-phosphorylation was followed by upregulation of Id1 mRNA and Id1 protein, whereas Id2 and Id3 expression was not affected. Furthermore, we found that BMP-6 had an antiproliferative effect both in naïve (CD19+CD27-) and memory B cells (CD19+CD27+) stimulated with anti-IgM alone or the combined action of anti-IgM and CD40L. Additionally, BMP-6 induced cell death in activated memory B cells. Importantly, the antiproliferative effect of BMP-6 in B-cells was completely neutralized by the natural antagonist, noggin. Furthermore, B cells were demonstrated to upregulate BMP-6 mRNA upon stimulation with anti-IgM.ConclusionIn mature human B cells, BMP-6 inhibited cell growth, and rapidly induced phosphorylation of Smad1/5/8 followed by an upregulation of Id1.

Effect of Gender and Sports on the Risk of Full-Thickness Articular Cartilage Lesions in Anterior Cruciate Ligament–Injured Knees A Nationwide Cohort Study From Sweden and Norway of 15 783 Patients

Background: The presence of an articular cartilage lesion in anterior cruciate ligament–injured knees is considered a predictor of osteoarthritis. Purpose: This study was undertaken to evaluate risk factors for full-thickness articular cartilage lesions in anterior cruciate ligament–injured knees, in particular the role of gender and the sport causing the initial injury. Study Design: Cohort study (prognosis); Level of evidence, 2. Methods: Primary unilateral anterior cruciate ligament reconstructions prospectively registered in the Swedish and the Norwegian National Knee Ligament Registry during 2005 through 2008 were included (N = 15 783). Logistic regression analyses were used to evaluate risk factors for cartilage lesions. Results: A total of 1012 patients (6.4%) had full-thickness cartilage lesions. The median time from injury to surgery was 9 months (range, 0 days-521 months). Male patients had an increased odds of full-thickness cartilage lesions compared with females (odds ratio = 1.22; 95% confidence interval, 1.04-1.42). In males, team handball had an increase in the odds of full-thickness cartilage lesions compared with soccer (odds ratio = 2.36; 95% confidence interval, 1.33-4.19). Among female patients, no sport investigated showed a significant decrease or increase in the odds of full-thickness cartilage lesions. The odds of a full-thickness cartilage lesion increased by 1.006 (95% confidence interval, 1.005-1.008) for each month elapsed from time of injury until anterior cruciate ligament reconstruction when all patients were considered, while time from injury to surgery did not affect the odds significantly in those patients reconstructed within 1 year of injury (odds ratio = 0.98; 95% confidence interval, 0.95-1.02). Previous surgery increased the odds of having a full-thickness cartilage lesion (odds ratio = 1.40; 95% confidence interval, 1.21-1.63). One year of increasing patient age also increased the odds (odds ratio = 1.05; 95% confidence interval, 1.05-1.06). Conclusion: Male gender is associated with an increased risk of full-thickness articular cartilage lesions in anterior cruciate ligament–injured knees. Male team handball players had an increased risk of full-thickness lesions. No other sports investigated were found to have significant effect on the risk in either gender. Furthermore, age, previous surgery, and time from injury to surgery exceeding 12 months are risk factors for full-thickness cartilage lesions.

Inhibitory effects and target genes of bone morphogenetic protein 6 in Jurkat TAg cells

Bone morphogenetic proteins (BMP) are multifunctional cytokines that belong to the TGF‐β superfamily. BMP have been shown to regulate haematopoietic stem cells, B lymphopoiesis and early thymocyte differentiation. In the present study we explored the role of BMP‐6 in Jurkat TAg cells. BMP‐6 rapidly induced phosphorylation of Smad1/5/8, p38 and ERK1/2, followed by a potent up‐regulation of ID1, ID2 and ID3. ID1 and ID3 were also induced at the protein level. Genome‐wide expression profiling of cells treated with BMP‐6 compared to medium confirmed that ID1–ID3 were target genes of BMP‐6 together with Noggin and Smad6. Furthermore, several genes involved in transcriptional regulation were also identified, including NFKBIA, HEY1, DLX2, KLF10 and early growth response 1. Stimulation with BMP‐6 exerted an antiproliferative effect that was counteracted by inhibitor of DNA binding (Id)1 siRNA, indicating that Id1 is an important downstream mediator in Jurkat TAg cells. A subset of CD4+ T cells were found to express the BMP receptors Alk‐2 and Alk‐3 (type I), in addition to BMPRII (type II). BMP‐6 also induced phosphorylation of Smad1/5/8, followed by transcriptional increase in ID1–ID3 mRNA expression. However, we did not observe significant changes in Id protein expression in CD4+ T cells. Altogether, the data indicate a role for BMP‐6 in human T lineage cells.

Distal radius fractures in children: substantial difference in stability between buckle and greenstick fractures

Background and purpose Numerous follow-up visits for wrist fractures in children are performed without therapeutic consequences. We investigated the degree to which the follow-up visits reveal complications and lead to change in management. The stability of greenstick and buckle fractures of the distal radius was assessed by comparing the lateral angulation radiographically. Patients and methods The medical records of 305 distal radius fractures in patients aged less than 16 years treated at our institution in 2006 were reviewed, and any complications were noted. The fracture type was determined from the initial radiographs and the angulation on the lateral films was noted. Results Only 1 of 311 follow-ups led to an active intervention. The greenstick fractures had more complications than the buckle fractures. The lateral angulation of the buckle fractures did not change importantly throughout the treatment. The greenstick fractures displaced 5° on average, and continued to displace after the first 2 weeks. On average, the complete fractures displaced 9°. Conclusion Buckle fractures are stable and do not require follow-up. Greenstick fractures are unstable and continue to displace after 2 weeks. Complete fractures of the distal radius are uncommon in children, and highly unstable. A precise classification of fracture type at the time of diagnosis would identify a smaller subset of patients that require follow-up.

PI3K/Akt-dependent Epo-induced signalling and target genes in human early erythroid progenitor cells

Erythropoietin (Epo) is the major regulator of differentiation, proliferation and survival of erythroid progenitors, but the Epo‐induced changes in gene expression that lead to these effects are not fully understood. The aim of this study was to examine how Epo, via activation of phosphatidylinositol 3‐kinase (PI3K)/Akt, exerts its role in the development of erythroid progenitors from CD34+ cells, and to identify early Epo target genes in human erythroid progenitors. In CD34+ progenitor cells, Epo alone was able to induce cell cycle progression as demonstrated by upregulation of cyclin D3, E and A leading to hyperphosphorylation of the retinoblastoma protein (RB). These effects were completely counteracted by the PI3K inhibitor LY294002. Furthermore, enforced expression of an activated form of Akt kinase highly augmented Epo‐induced erythropoiesis. Fluorescent‐activated cell sorting (FACS)‐sorted CD34+CD71+CD45RA−GPA− erythroid progenitors stimulated with Epo in the presence or absence of LY294002 were subjected to gene expression profiling. Several novel target genes of Epo were identified, and the majority were regulated in a PI3K‐dependent manner, including KIT (CD117) and CDH1 (E‐cadherin). FACS analysis of Epo‐stimulated erythroid progenitors showed that the increased mRNA expression of KIT and CDH1 was accompanied by an induction of the corresponding proteins CD117 and E‐cadherin.

Classification of distal radius fractures in children: good inter- and intraobserver reliability, which improves with clinical experience

BackgroundWe wanted to test the reliability of a commonly used classification of distal radius fractures in children.Methods105 consecutive fractures of the distal radius in children were rated on two occasions three months apart by 3 groups of doctors; 4 junior registrars, 4 senior registrars and 4 orthopedic consultants. The fractures were classified as buckle, greenstick, complete or physeal. Kappa statistics were used to analyze inter- and intraobserver reliability.ResultsThe kappa value for interobserver agreement at the first reading was 0.59 for the junior registrars, 0.63 for the senior registrars and 0.66 for the consultants. The mean kappa value for intraobserver reliability was 0.79 for the senior registrars, 0.74 for the consultants and 0.66 for the junior registrars.ConclusionsWe conclude that the classification tested in this study is reliable and reproducible when applied by raters experienced in fracture management. The reliability varies according to the experience of the raters. Experienced raters can verify the classification, and avoid unnecessary follow-up appointments.

Long-term patient-reported outcome after fractures of the clavicle in patients aged 10 to 18 years.

Background: Fractures of the clavicle are common among adolescents and have traditionally been treated nonoperatively. Recent literature has demonstrated less satisfactory results than expected after conservative management of displaced fractures in adults. The purpose of this study was to evaluate the long-term patient-reported outcome after clavicle fractures in older children and adolescents. Methods: Children aged 10 to 18 years who sustained a fracture of the clavicle between 2006 and 2008 were identified in our institution’s computerized files. The radiographs were examined and the fracture patterns, degree of dislocation, and shortening were measured. Medical records were reviewed and the patient-reported outcome was assessed using the Oxford Shoulder score and the Quick version of the Disability of Arm, Shoulder, and Hand questionnaire, and specific and general satisfaction scores. Results: A total of 185 patients (median age, 14.4 y) with 172 midshaft and 13 lateral fractures were included in the study. Sixty-five (37.8%) of the midshaft fractures were displaced, and 9 of these were operated. There was one case of nonunion and one delayed union. One hundred twenty-two (70.9%) of the patients with a midshaft fracture responded to the questionnaires on an average 4.7 years after injury. Overall results were good to excellent for the majority of nonoperatively treated patients; however, shortening of the fracture had a negative effect on the Oxford Shoulder score (P=0.02), the cosmetic satisfaction score (P=0.02), and the overall satisfaction score (P=0.01). Conclusions: The long-term patient-reported outcome after nonoperatively treated fractures of the clavicle in adolescents is good to excellent for the majority of the patients, and nonunion is rare. However, shortening of the fracture had a small negative effect on the outcome. Conservative management should remain the mainstay of management for fractures of the clavicle in this age group. Level of Evidence: Level IV—retrospective case series.