Do Orthopaedic Virtual Clinic Visits Demonstrate Cost and Time Efficiencies Compared With In-person Visits?

BACKGROUND

There are numerous reasons for the increased use of telemedicine in orthopaedic surgery, one of which is the perception that virtual visits are more cost-effective than in-person visits. However, to our knowledge, no studies have compared the cost and time investment of virtual versus in-person visits using the time-driven activity-based costing (TDABC) method. Unlike methods that estimate cost based on charges for services rendered, TDABC provides a more precise measurement of costs, which is essential for assessing cost-effective innovations and moving to value-based healthcare.

QUESTIONS/PURPOSES

(1) Are virtual visits less costly than analogous in-person visits, as measured by TDABC? (2) Does TDABC yield cost estimates that are lower or higher than the ratio of costs to charges (RCC), which is a simple, frequently used costing method? (3) Do the total time commitments of healthcare personnel, and that of the surgeon specifically, vary between the virtual and in-person settings?

METHODS

Patients for this prospective, observational study were recruited from the practices of the highest-volume virtual-visit surgeons of three subspecialties (joints, hand, and sports) in a multihospital, tertiary-care academic institution in a metropolitan area in the Midwestern United States. Each surgeon had at least 10 years of clinical practice. Between June 2021 and September 2021, we analyzed both in-person and virtual return visits with patients who had an established relationship with the surgeon, because this represented the most frequent type of virtual visits and enabled a direct comparison between the two settings. New patients were not included in the study because of the limited availability of new-patient virtual visits; such patients often benefit from in-person physical examinations and on-site imaging. Additionally, patients seen for routine postoperative care were excluded because they were primarily seen in person by a physician assistant. Data were acquired during this period until 90 in-person and 90 virtual visits were collected according to selection criteria; no patients were lost to follow-up. Distinct process maps, which represent the steps involved in a clinic visit used to measure healthcare personnel time invested, were constructed for in-person and virtual clinic visits and used to compare total personnel and surgeon time spent. To calculate TDABC-derived costs, time allocated by personnel to complete each step was measured and used to calculate cost based on each personnel member's yearly salary. From the accounting department of our hospital, we acquired RCC cost data according to the level of service for a return visit.

RESULTS

The total median cost, as measured by TDABC, was USD 127 (IQR USD 111 to 163) for an in-person visit and USD 140 (IQR USD 113 to 205) for a virtual visit (median difference USD 13; p = 0.16). RCC overestimated TDABC-calculated direct variable cost in five of six service levels (in-person levels 3, 4, and 5 and virtual levels 3 and 5) by a range of USD 25 to 88. Additionally, we found that virtual visits consumed 4 minutes less of total personnel time (in-person: 17 minutes [IQR 13.5 to 23.5 minutes], virtual: 13 minutes [IQR 11 to 19 minutes]; p < 0.001); however, this difference in personnel time did not equate to cost savings because surgeons spent 2 minutes longer on virtual visit activities than they did on in-person activities (in-person: 6 minutes [IQR 4.5 to 9.5 minutes], virtual: 8 minutes [IQR 5.5 to 13 minutes]; p = 0.003).

CONCLUSION

Orthopaedic virtual visits did not deliver cost savings compared with in-person visits because surgeons spent more time on virtual visits and participated in virtual visits at the clinical site. Additionally, as anticipated, RCC overestimated costs as calculated by TDABC. These findings suggest that cost is not a primary advantage of transitioning to virtual visits, and that factors such as patient preference and satisfaction should be considered instead.

LEVEL OF EVIDENCE

Level II, economic and decision analysis.

A randomized, triple-blinded controlled clinical study with a novel disease-modifying drug combination in equine lameness-associated osteoarthritis

Objective

This study aimed to test a novel treatment combination (TC) (equivalent to sildenafil, mepivacaine, and glucose) with disease-modifying properties compared to Celestone® bifas® (CB) in a randomized triple-blinded phase III clinical study in horses with mild osteoarthritis (OA). Joint biomarkers (reflecting the articular cartilage and subchondral bone remodelling) and clinical lameness were used as readouts to evaluate the treatment efficacy.

Methods

Twenty horses with OA-associated lameness in the carpal joint were included in the study and received either TC (n = 10) or CB (n = 10) drug intra-articularly-twice in the middle carpal joint with an interval of 2 weeks (visit 1 & 2). Clinical lameness was assessed both objectively (Lameness locator) and subjectively (visually). Synovial fluid and serum were sampled for quantification of the extracellular matrix (ECM) neo-epitope joint biomarkers represented by biglycan (BGN²⁶²) and cartilage oligomeric matrix protein (COMP¹⁵⁶). Another two weeks later clinical lameness was recorded, and serum was collected for biomarkers analysis. The overall health status was compared pre and post-intervention by interviewing the trainer.

Results

Post-intervention, SF BGN²⁶² levels significantly declined in TC (P = 0.002) and COMP¹⁵⁶ levels significantly increased in CB (P = 0.002). The flexion test scores improved in the TC compared to CB (P =0.033) and also had an improved trotting gait quality (P =0.044). No adverse events were reported.

Conclusion

This is the first clinical study presenting companion diagnostics assisting in identifying OA phenotype and evaluating the efficacy and safety of a novel disease-modifying osteoarthritic drug.

Systematic evidence map (SEM) template: Report format and methods used for the US EPA Integrated Risk Information System (IRIS) program, Provisional Peer Reviewed Toxicity Value (PPRTV) program, and other "fit for purpose" literature-based human health analyses

BACKGROUND

Systematic evidence maps (SEMs) are gaining visibility in environmental health for their utility to serve as problem formulation tools and assist in decision-making, especially for priority setting. SEMs are now routinely prepared as part of the assessment development process for the US Environmental Protection Agency (EPA) Integrated Risk Information System (IRIS) and Provisional Peer Reviewed Toxicity Value (PPRTV) assessments. SEMs can also be prepared to explore the available literature for an individual chemical or groups of chemicals of emerging interest.

OBJECTIVES

This document describes the typical methods used to produce SEMs for the IRIS and PPRTV Programs, as well as "fit for purpose" applications using a variety of examples drawn from existing analyses. It is intended to serve as an example base template that can be adapted as needed for the specific SEM. The presented methods include workflows intended to facilitate rapid production. The Populations, Exposures, Comparators and Outcomes (PECO) criteria are typically kept broad to identify mammalian animal bioassay and epidemiological studies that could be informative for human hazard identification. In addition, a variety of supplemental content is tracked, e.g., studies presenting information on in vitro model systems, non-mammalian model systems, exposure-level-only studies in humans, pharmacokinetic models, and absorption, distribution, metabolism, and excretion (ADME). The availability of New Approach Methods (NAMs) evidence is also tracked (e.g., high throughput, transcriptomic, in silico, etc.). Genotoxicity studies may be considered as PECO relevant or supplemental material, depending on the topic and context of the review. Standard systematic review practices (e.g., two independent reviewers per record) and specialized software applications are used to search and screen the literature and may include the use of machine learning software. Mammalian bioassay and epidemiological studies that meet the PECO criteria after full-text review are briefly summarized using structured web-based extraction forms with respect to study design and health system(s) assessed. Extracted data is available in interactive visual formats and can be downloaded in open access formats. Methods for conducting study evaluation are also presented which is conducted on a case-by-case basis, depending on the usage of the SEM.

7-Tesla MRI Evaluation of the Knee, 25 Years after Cartilage Repair Surgery: The Influence of Intralesional Osteophytes on Biochemical Quality of Cartilage

OBJECTIVE

To evaluate the morphological and biochemical quality of cartilage transplants and surrounding articular cartilage of patients 25 years after perichondrium transplantation (PT) and autologous chondrocyte transplantation (ACT) as measured by ultra-high-field 7-Tesla (7T) magnetic resonance imaging (MRI) and to present these findings next to clinical outcome.

DESIGN

Seven PT patients and 5 ACT patients who underwent surgery on the femoral condyle between 1986 and 1996 were included. Patient-reported outcome measures (PROMs) were assessed by the clinical questionnaires: Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC), and Visual Analogue Scale (VAS) for knee pain. The morphological (MOCART score) and biochemical quality (glycosaminoglycans [GAGs] content and collagen integrity) of cartilage transplants and surrounding articular cartilage were analyzed by 7T MRI. The results of the PT and ACT patients were compared. Finally, a detailed morphological analysis of the grafts alone was performed.

RESULTS

No statistically significant difference was found for the PROMs and MOCART scores of PT and ACT patients. Evaluation of the graft alone showed poor repair tissue quality and high prevalence of intralesional osteophyte formation in both the PT and ACT patients. Penetration of the graft surface by the intralesional osteophyte was related to biochemically damaged opposing tibial cartilage; GAG content was significantly lower in patients with an osteophyte penetrating the graft surface.

CONCLUSIONS

Both PT and ACT patients have a high incidence of intralesional osteophyte formation 25 years after surgery. The resulting biochemical damage to the opposing tibial cartilage might be dependent on osteophyte morphology.

Isolation precautions cause minor delays in diagnostics and treatment of non-COVID patients

Background

Isolation precautions are essential prevent spread of COVID-19 infection but may have a negative impact on inpatient care. The impact of these measures on non-COVID-19 patients remains largely unexplored.

Aim

This study aimed to investigate diagnostic and treatment delays related to isolation precautions, the associated patient outcome, and the predisposing risk factors for delays.

Methods

This observational study was conducted in seven Helsinki region hospitals during the first wave of the COVID-19 pandemic in Finland. The study used data on all non-COVID-19 inpatients, who were initially isolated due to suspected COVID-19, to estimate whether isolation precautions resulted in diagnostic or treatment delays.

Results

Out of 683 non-COVID-19 patients, 33 (4.8%) had delays related to isolation precautions. Clinical condition deteriorated non-fatally in seven (1.0%) patients. The following events were associated with an increased risk of treatment or a diagnostic delay: more than three ward transfers (P = 0.025); referral to an incorrect speciality in the emergency department (P = 0.004); more than three SARS-CoV-2 RT-PCR tests performed (P = 0.022); and where cancer was the final diagnosis (P = 0.018). In contrast, lower respiratory tract symptoms (P = 0.013) decreased the risk.

Conclusions

The use of isolation precautions for patients who did not have COVID-19 had minor negative effects on patient outcomes. The present study underlines the importance of targeting diagnostic efforts to patients with unspecified symptoms and to those with a negative SARS-CoV-2 test result. Thorough investigations to achieve an accurate diagnosis improves the prognosis of patients and facilitates appropriate targeting of hospital resources.

Nerve growth factor in the equine joint

Nerve growth factor (NGF) is a neurotrophin with many functions. In humans, it is involved in inflammation, nerve growth, apoptosis and pain signalling. Increased concentrations of NGF in synovial fluid has been shown in humans and dogs with osteoarthritis. Despite osteoarthritis being a common problem in horses, no studies have previously been published on NGF in the equine joint. The aim of this study was to quantify NGF in equine synovial fluid from healthy joints, acutely inflamed septic joints and joints with structural changes associated with osteoarthritis. A secondary aim was to identify the localisation of NGF and its two receptors, TrkA and p75^NTR, in healthy and osteoarthritic articular cartilage. NGF concentrations in synovial fluid from osteoarthritic joints (n = 27), septic joints (n = 9) and healthy joints (n = 16) were determined by ELISA. In addition, articular cartilage from osteoarthritic and healthy joints was examined for NGF, TrkA and p75^NTR using immunohistochemistry staining. NGF was present in equine synovial fluid and articular cartilage. Compared to synovial fluid from healthy joints, NGF concentration was higher in synovial fluid from joints with structural osteoarthritic changes (P = 0.032) or acute septic inflammation (P = 0.006). In articular cartilage with severe osteoarthritic changes, there was more abundant positive immunohistochemistry staining for NGF and its receptors than in normal articular cartilage. Further studies should focus on identifying precursor forms of NGF, and on receptor expression and downstream signalling of TrkA and P75^NTR in health and disease.

Effect of circadian rhythm, age, training and acute lameness on serum concentrations of cartilage oligomeric matrix protein (COMP) neo-epitope in horses

Background

Molecular serum markers that can identify early reversible osteoarthritis (OA) in horses are lacking.

Objectives

We studied serum concentrations of a novel cartilage oligomeric matrix protein (COMP) neo‐epitope in horses subjected to short‐term exercise and with acute lameness. The effects of circadian rhythm and age were also evaluated.

Study design

Longitudinal studies in healthy horses and cross‐sectional comparison of lame and non‐lame horses.

Methods

Sera were collected from five horses before and after short‐term interval exercise and during full‐day box rest. Sera from 32 acutely lame horses were used to evaluate age‐related effects. Independent samples from control horses (n = 41) and horses with acute lameness (n = 71) were included. COMP neo‐epitope concentrations were analysed using custom‐developed inhibition ELISAs validated for equine serum. The presence of COMP neo‐epitope was delineated in healthy and osteoarthritic articular cartilage with immunohistochemistry.

Results

COMP neo‐epitope concentrations decreased after speed training but returned to baseline levels post‐exercise. No correlations between age and serum COMP neo‐epitope concentrations were found (r = 0.0013). The mean (±s.d.) serum concentration of COMP neo‐epitope in independent samples from non‐lame horses was 0.84 ± 0.38 μg/mL, and for lame horses was 5.24 ± 1.83 μg/mL (P<0.001). Antibodies against COMP neo‐epitope did not stain normal articular cartilage, but intracytoplasmic staining was found in superficial chondrocytes of mild OA cartilage and in the extracellular matrix of moderately osteoarthritic cartilage.

Main limitations

ELISA was based on polyclonal antisera rather than a monoclonal antibody. There is a sex and breed bias within the groups of horses, also it could have been of value to include horses with septic arthritis and tendonitis and investigated joint differences.

Conclusions

This COMP neo‐epitope can be measured in sera, and results indicate that it could be a biomarker for pathologic fragmentation of cartilage in connection with acute joint lameness.

Cartilage oligomeric matrix protein neoepitope in the synovial fluid of horses with acute lameness: A new biomarker for the early stages of osteoarthritis

Background

Clinical tools to diagnose the early changes of osteoarthritis (OA) that occur in the articular cartilage are lacking.

Objectives

We sought to identify and quantify a novel cartilage oligomeric matrix protein (COMP) neoepitope in the synovial fluid from the joints of healthy horses and those with different stages of OA.

Study design

In vitro quantitative proteomics and assay development with application in synovial fluids samples obtained from biobanks of well‐characterised horses.

Methods

Articular cartilage explants were incubated with or without interleukin‐1β for 25 days. Media were analysed via quantitative proteomics. Synovial fluid was obtained from either normal joints (n = 15) or joints causing lameness (n = 17) or with structural OA lesions (n = 7) and analysed for concentrations of the COMP neoepitope using a custom‐developed inhibition enzyme‐linked immunosorbent assay (ELISA). Explants were immunostained with polyclonal antibodies against COMP and the COMP neoepitopes.

Results

Semitryptic COMP peptides were identified and quantified in cell culture media from cartilage explants. A rabbit polyclonal antibody was raised against the neoepitope of the N‐terminal portion of one COMP fragment (sequence SGPTHEGVC). An inhibition ELISA was developed to quantify the COMP neoepitope in synovial fluid. The mean concentration of the COMP neoepitope significantly increased in the synovial fluid from the joints responsible for acute lameness compared with normal joints and the joints of chronically lame horses and in joints with chronic structural OA. Immunolabelling for the COMP neoepitope revealed a pericellular staining in the interleukin‐1β‐stimulated explants.

Main limitations

The ELISA is based on polyclonal antisera rather than a monoclonal antibody.

Conclusions

The increase in the COMP neoepitope in the synovial fluid from horses with acute lameness suggests that this neoepitope has the potential to be a unique candidate biomarker for the early molecular changes in articular cartilage associated with OA.

Combined cognitive-behavioural and mindfulness programme for people living with dystonia: a proof-of-concept study

OBJECTIVES

To design and test the delivery of an intervention targeting the non-motor symptoms of dystonia and pilot key health and well-being questionnaires in this population.

DESIGN

A proof-of-concept study to test the delivery, acceptability, relevance, structure and content for a 3-day group residential programme for the management of dystonia.

SETTING

Participants were recruited from a single botulinum toxin clinic. The intervention was delivered in the community.

PARTICIPANTS

14 participants consented to take part (2 withdrew prior to the starting of intervention). The average age was 60 years (range 44-77), 8 of whom were female. After drop-out, 9 participants completed the 3-day programme.

INTERVENTION

A 3-day group residential programme.

PRIMARY AND SECONDARY OUTCOME MEASURES

Process evaluation and interviews were carried out before and after the intervention to explore participant's views and expectations, as well as experiences of the intervention. Select questionnaires were completed at baseline, 1-month and 3-month follow-up.

RESULTS

Although participants were not sure what to expect from the programme, they found it informative and for many this together with being in a group with other people with dystonia legitimised their condition. Mindfulness was accepted and adopted as a coping strategy. This was reflected in the 1-month follow-up.

CONCLUSIONS

We successfully delivered a 3-day residential programme to help those living with dystonia manage their condition. Further improvements are suggested. The quantitative outcome measures were acceptable to this group of patients with dystonia.

Characterisation of lubricin in synovial fluid from horses with osteoarthritis

REASON FOR PERFORMING STUDY

The glycoprotein lubricin contributes to the boundary lubrication of the articular cartilage surface. The early events of osteoarthritis involve the superficial layer where lubricin is synthesised.

OBJECTIVES

To characterise the glycosylation profile of lubricin in synovial fluid from horses with osteoarthritis and study secretion and degradation of lubricin in an in vitro inflammation cartilage model.

STUDY DESIGN

In vitro study.

METHODS

Synovial fluid samples collected from horses with joints with normal articular cartilage and structural osteoarthritic lesions; with and without osteochondral fragments, were analysed for the lubricin glycosylation profiles. Articular cartilage explants were stimulated with or without interleukin-1β for 25 days. Media samples collected at 3-day intervals were analysed by quantitative proteomics, western blot and enzyme-linked immunosorbent assay.

RESULTS

O-glycosylation profiles in synovial fluid revealed both Core 1 and 2 O-glycans, with Core 1 O-glycans predominating. Synovial fluid from normal joints (49.5 ± 1.9%) contained significantly lower amounts of monosialylated Core 1 O-glycans compared with joints with osteoarthritis (53.8 ± 7.8%, P = 0.03) or joints with osteochondral fragments (57.3 ± 8.8%, P = 0.001). Additionally, synovial fluid from normal joints (26.7 ± 6.7%) showed higher amounts of disialylated Core 1 O-glycan than from joints with osteochondral fragments (21.2 ± 4.9%, P = 0.03). A C-terminal proteolytic cleavage site in lubricin was found in synovial fluid from normal and osteochondral fragment joints and in media from interleukin-1β stimulated and unstimulated articular cartilage explants.

CONCLUSIONS

This is the first demonstration of a change in the glycosylation profile of lubricin in synovial fluid from diseased equine joints compared with that from normal joints. We demonstrate an identical proteolytic cleavage site of lubricin both in vitro and in vivo. The reduced sialation of lubricin in synovial fluid from diseased joints may affect the boundary lubricating ability of the superficial layer of articular cartilage and could be one of the early events in the progression of osteoarthritis.

GDF5 reduces MMP13 expression in human chondrocytes via DKK1 mediated canonical Wnt signaling inhibition

OBJECTIVE

Growth differentiation factor 5 (GDF5) is important for joint formation and associated with osteoarthritis (OA). Its role for the homeostasis of cartilage extracellular matrix (ECM) is, however, unknown. The canonical Wnt signaling pathway is also implemented in OA and activation of the pathway has detrimental effects on the cartilage ECM. The objective of this study was to investigate the effect of GDF5 stimulation on the Wnt signaling pathway and on the expression of known modulators of cartilage ECM.

DESIGN

Human chondrocytes were cultured in the pellet mass system and stimulated with increasing concentrations of GDF5. Expression of matrix modulating enzymes and canonical Wnt inhibitors dickkopf 1 (DKK1) and frizzled related protein (FRZB) were measured with quantitative PCR (qPCR). Protein levels of matrix metalloprotease 13 (MMP13), DKK1 and β-catenin were measured with enzyme-linked immunosorbent assay (ELISA). Canonical Wnt signaling was stimulated with Wnt3a and small molecule CHIR-99021 and DKK1 was blocked with small molecule WAY-262611.

RESULTS

In this study, we show that GDF5 stimulation of human chondrocytes inhibits expression of the cartilage ECM degrading enzymes MMP13 and ADAMTS4 and stimulates the expression of cartilage anabolic genes ACAN and SOX9. We further show that the stimulation inhibits the canonical Wnt signaling pathway through expression of the canonical Wnt inhibitors DKK1 and FRZB. Finally we show that inhibition of MMP13 expression through GDF5 stimulation is mediated by DKK1.

CONCLUSION

Herein, we provide evidence of a previously unknown link between GDF5 signaling and canonical Wnt signaling that may contribute to the understanding of the molecular mechanisms of OA.

Hydroxyapatite coating affects the Wnt signaling pathway during peri-implant healing in vivo

Owing to its bio- and osteoconductivity, hydroxyapatite (HA) is a widely used implant material, but its osteogenic properties are only partly evaluated in vitro and in vivo. The present study focused on bone healing adjacent to HA-coated titanium (Ti) implants, with or without incorporated lithium ions (Li(+)). Special attention was given to the Wnt signaling pathway. The implants were inserted into rat tibia for 7 or 28 days and analyzed ex vivo, mainly by histomorphometry and quantitative real-time polymerase chain reaction (qPCR). HA-coated implants showed, irrespective of Li(+) content, bone-implant contact (BIC) and removal torque values significantly higher than those of reference Ti. Further, the expression of OCN, CTSK, COL1A1, LRP5/6 and WISP1 was significantly higher in implant-adherent cells of HA-coated implants, with or without Li(+). Significantly higher β-catenin expression and significantly lower COL2A1 expression were observed in peri-implant bone cells from HA with 14 ng cm(-2) released Li(+). Interestingly, Ti implants showed a significantly larger bone area (BA) in the threads than HA with 39 ng cm(-2) released Li(+), but had a lower BIC than any HA-coated implant. This study shows that HA, with or without Li(+), is a strong activator of the Wnt signaling pathway, and may to some degree explain its high bone induction capacity.

Acoustic monitoring of changes in well-defined hyaluronan layers exposed to chondrocytes

The interaction of human-derived chondrocytes and thin hyaluronan layers was studied using the quartz crystal microbalance with dissipation (QCM-D) technique combined with light microscopy.

Biocompatibility and resorption of a radiopaque premixed calcium phosphate cement

Calcium phosphate cements (CPC) are used as bone void filler in various orthopedic indications; however, there are some major drawbacks regarding mixing, transfer, and injection of traditional CPC. By using glycerol as mixing liquid, a premixed calcium phosphate cement (pCPC), some of these difficulties can be overcome. In the treatment of vertebral fractures the handling characteristics need to be excellent including a high radio-opacity for optimal control during injection. The aim of this study is to evaluate a radiopaque pCPC regarding its resorption behavior and biocompatibility in vivo. pCPC and a water-based CPC were injected into a Ø 4-mm drilled femur defect in rabbits. The rabbits were sacrificed after 2 and 12 weeks. Cross sections of the defects were evaluated using histology, electron microscopy, and immunohistochemical analysis. Signs of inflammation were evaluated both locally and systemically. The results showed a higher bone formation in the pCPC compared to the water-based CPC after 2 weeks by expression of RUNX-2. After 12 weeks most of the cement had been resorbed in both groups. Both materials were considered to have a high biocompatibility since no marked immunological response was induced and extensive bone ingrowth was observed. The conclusion from the study was that pCPC with ZrO(2) radiopacifier is a promising alternative regarding bone replacement material and may be suggested for treatment of, for example, vertebral fractures based on its high biocompatibility, fast bone ingrowth, and good handling properties.

Characteristic Markers of the WNT Signaling Pathways Are Differentially Expressed in Osteoarthritic Cartilage

OBJECTIVE

It is well known that expression of markers for WNT signaling is dysregulated in osteoarthritic (OA) bone. However, it is still not fully known if the expression of these markers also is affected in OA cartilage. The aim of this study was therefore to examine this issue.

METHODS

Human cartilage biopsies from OA and control donors were subjected to genome-wide oligonucleotide microarrays. Genes involved in WNT signaling were selected using the BioRetis database, KEGG pathway analysis was searched using DAVID software tools, and cluster analysis was performed using Genesis software. Results from the microarray analysis were verified using quantitative real-time PCR and immunohistochemistry. In order to study the impact of cytokines for the dysregulated WNT signaling, OA and control chondrocytes were stimulated with interleukin-1 and analyzed with real-time PCR for their expression of WNT-related genes.

RESULTS

Several WNT markers displayed a significantly altered expression in OA compared to normal cartilage. Interestingly, inhibitors of the canonical and planar cell polarity WNT signaling pathways displayed significantly increased expression in OA cartilage, while the Ca(2+)/WNT signaling pathway was activated. Both real-time PCR and immunohistochemistry verified the microarray results. Real-time PCR analysis demonstrated that interleukin-1 upregulated expression of important WNT markers.

CONCLUSIONS

WNT signaling is significantly affected in OA cartilage. The result suggests that both the canonical and planar cell polarity WNT signaling pathways were partly inhibited while the Ca(2+)/WNT pathway was activated in OA cartilage.

Investigation of different cell types and gel carriers for cell-based intervertebral disc therapy, in vitro and in vivo studies

Biological treatment options for the repair of intervertebral disc damage have been suggested for patients with chronic low back pain. The aim of this study was to investigate possible cell types and gel carriers for use in the regenerative treatment of degenerative intervertebral discs (IVD). In vitro: human mesenchymal cells (hMSCs), IVD cells (hDCs), and chondrocytes (hCs) were cultivated in three gel types: hyaluronan gel (Durolane®), hydrogel (Puramatrix®), and tissue-glue gel (TISSEEL®) in chondrogenic differentiation media for 9 days. Cell proliferation and proteoglycan accumulation were evaluated with microscopy and histology. In vivo: hMSCs or hCs and hyaluronan gel were co-injected into injured IVDs of six minipigs. Animals were sacrificed at 3 or 6 months. Transplanted cells were traced with anti-human antibodies. IVD appearance was visualized by MRI, immunohistochemistry, and histology. Hyaluronan gel induced the highest cell proliferation in vitro for all cell types. Xenotransplanted hMSCs and hCs survived in porcine IVDs for 6 months and produced collagen II in all six animals. Six months after transplantation of cell/gel, pronounced endplate changes indicating severe IVD degeneration were observed at MRI in 1/3 hC/gel, 1/3 hMSCs/gel and 1/3 gel only injected IVDs at MRI and 1/3 hMSC/gel, 3/3 hC/gel, 2/3 gel and 1/3 injured IVDs showed positive staining for bone mineralization. In 1 of 3 discs receiving hC/gel, in 1 of 3 receiving hMSCs/gel, and in 1 of 3 discs receiving gel alone. Injected IVDs on MRI results in 1 of 3 hMSC/gel, in 3 of 3 hC/gel, in 2 of 3 gel, and in 1 of 3 injured IVDs animals showed positive staining for bone mineralization. The investigated hyaluronan gel carrier is not suitable for use in cell therapy of injured/degenerated IVDs. The high cell proliferation observed in vitro in the hyaluronan could have been a negative factor in vivo, since most cell/gel transplanted IVDs showed degenerative changes at MRI and positive bone mineralization staining. However, this xenotransplantation model is valuable for evaluating possible cell therapy strategies for human degenerated IVDs.

HES1 and HES5 are dispensable for cartilage and endochondral bone formation

Notch signalling, via its downstream mediators HES1 and HES5, regulates development of several different tissues. In vitro studies suggest that these genes are also involved in chondrogenesis and endochondral bone formation. In order to investigate the importance of HES1 and HES5 for these developmental processes, mice lacking chondrogenic expression of HES1 and HES5 were constructed by interbreeding HES5(-/-) mice homozygous for the floxed HES1 allele (HES1(flox/flox)) with COL2A1-Cre transgenic mice, creating conditional HES1;HES5 double mutant mice. The formation of cartilage and endochondral bone was studied in these mice using histological and immunohistochemical stainings, including Alcian Blue van Gieson, Safranin-O, modified Mallory Aniline Blue, tartrate-resistant acid phosphatase and collagen type II stainings. The mice were also studied using several different morphometrical analyses and the differentiation potential of the chondrocytes was evaluated in vitro. Unexpectedly, the conditional HES1;HES5 double mutant mice did not display impaired development of cartilage or endochondral bone. Lack of altered phenotype in the conditional HES1;HES5 double mutant mice can be explained either by the HES1 and HES5 genes not being involved in cartilage and endochondral bone development or by functional redundancy between the genes belonging to the family of HES genes: that is, disruption of one gene could be compensated for by the activity of another. Our results further shed light on the compensatory reserves available during the developing cartilage and bone.

Human disk cells from degenerated disks and mesenchymal stem cells in co-culture result in increased matrix production

Transplantation of mesenchymal stem cells (MSCs) has been suggested for disk degeneration, which is characterized by dysfunctional cells and low proteoglycan production. The aim of this study was to examine the effects of a 3D co-culture system using human disk cells (DCs) and MSCs on collagen and proteoglycan production. DCs and MSCs were expanded in monolayer and grown in pellet cultures for 7, 14 and 28 days and analyzed for hydroxyproline (HP), reflecting total collagen production, and glycosaminoglycan (GAG) accumulation. DCs and MSCs co-cultured at different ratios (25/75, 50/50 and 75%/25%) were examined for GAG accumulation. Collagen type II expression was analyzed immunohistochemically. In a second series, conditioned media were added to pellet cultures of degenerated DCs or MSCs. DCs from degenerated disks and MSCs demonstrated lower total collagen production than non-degenerated DC pellets. GAG production was comparable in DCs and MSCs, except in the youngest donor, with MSC producing about 10 times higher GAG/DNA. Co-cultures resulted in approximately 1.5 times higher GAG/DNA production than DCs. Increased collagen type II expression was seen in co-cultures compared to DC or MSC culture alone, except in the case with highly active MSCs. No positive effect of conditioned media was seen. In conclusion, co-culture of MSCs with degenerated DCs increased proteoglycan and collagen-type ceII production, indicating that in future clinical therapy MSCs can be transplanted without pre-differentiation in vitro. The lack of effect of conditioned media suggests that the positive effect of co-culture on matrix production is not due to soluble factors.

Topographic variation in redifferentiation capacity of chondrocytes in the adult human knee joint

OBJECTIVES

The aim of this study was to investigate the topographic variation in matrix production and cell density in the adult human knee joint. Additionally, we have examined the redifferentiation potential of chondrocytes expanded in vitro from the different locations.

METHOD

Full thickness cartilage-bone biopsies were harvested from seven separate anatomical locations of healthy knee joints from deceased adult human donors. Chondrocytes were isolated, expanded in vitro and redifferentiated in a pellet mass culture. Biochemical analysis of total collagen, proteoglycans and cellular content as well as histology and immunohistochemistry were performed on biopsies and pellets.

RESULTS

In the biochemical analysis of the biopsies, we found lower proteoglycan to collagen (GAG/HP) ratio in the non-weight bearing (NWB) areas compared to the weight bearing (WB) areas. The chondrocytes harvested from different locations in femur showed a significantly better attachment and proliferation ability as well as good post-expansion chondrogenic capacity in pellet mass culture compared with the cells harvested from tibia.

CONCLUSION

These results demonstrate that there are differences in extra cellular content within the adult human knee in respect to GAG/HP ratio. Additionally, the data show that clear differences between chondrocytes harvested from femur and tibia from healthy human knee joints exist and that the differences are not completely abolished during the process of de- and redifferentiation. These findings emphasize the importance of the understanding of topographic variation in articular cartilage biology when approaching new cartilage repair strategies.

Notch1, Jagged1, and HES5 are abundantly expressed in osteoarthritis

BACKGROUND

Notch signalling controls differentiation and proliferation in various cell types and is associated with several diseases. We investigated the localization and regulation of several Notch markers in human osteoarthritic (OA) cartilage as well as identified genes controlled by Notch signalling.

METHODS

Immunolocalization and real-time PCR analysis of Notch markers in healthy and OA articular cartilage were performed. Genes regulated by Notch signalling were studied using microarray. Cytokine-induced transcription of Notch markers was analyzed using real-time PCR and its effect on cellular localization of the intracellular domain of Notch1 (NICD1) was investigated using immunohistochemistry, subcellular fractionation, and transfection. The effect of NFkappaB activation on HES5 transcription was studied using the NFkappaB inhibitor pyrrolidine dithiocarbamate.

RESULTS

Notch signalling was activated in OA cartilage and Notch1, Jagged1, and HES5 were abundantly expressed compared to healthy cartilage. Notch signalling regulated the expression of several genes associated with OA, like interleukin-8, lubricin, CD10, matrix metalloproteinase-9, and bone morphogenetic protein-2. Cytokines significantly affected the expression of several Notch markers and repressed expression of HES5, but did not affect the cellular localization of NICD1.

CONCLUSION

Notch signalling is dysregulated in OA, inducing and repressing transcription of genes that could potentially partly contribute to the OA phenotype.

Immature porcine knee cartilage lesions show good healing with or without autologous chondrocyte transplantation

OBJECTIVE

The purpose of this study was to find out how deep chondral lesions heal in growing animals spontaneously and after autologous chondrocyte transplantation.

METHODS

A 6mm deep chondral lesion was created in the knee joints of 57 immature pigs and repaired with autologous chondrocyte transplantation covered with periosteum or muscle fascia, with periosteum only, or left untreated. After 3 and 12 months, the repair tissue was evaluated with International Cartilage Repair Society (ICRS) macroscopic grading, modified O'Driscoll histological scoring, and staining for collagen type II and hyaluronan, and with toluidine blue and safranin-O staining for glycosaminoglycans. The repair tissue structure was also examined with quantitative polarized light microscopy and indentation analysis of the cartilage stiffness.

RESULTS

The ICRS grading indicated nearly normal repair tissue in 65% (10/17) after the autologous chondrocyte transplantation and 86% (7/8) after no repair at 3 months. At 1 year, the repair tissue was nearly normal in all cases in the spontaneous repair group and in 38% (3/8) in the chondrocyte transplantation group. In most cases, the cartilage repair tissue stained intensely for glycosaminoglycans and collagen type II indicating repair tissue with true constituents of articular cartilage. There was a statistical difference in the total histological scores at 3 months (P=0.028) with the best repair in the spontaneous repair group. A marked subchondral bone reaction, staining with toluidine blue and collagen type II, was seen in 65% of all animals.

CONCLUSIONS

The spontaneous repair ability of full thickness cartilage defects of immature pigs is significant and periosteum or autologous chondrocytes do not bring any additional benefits to the repair.

In vivo MR imaging of magnetically labeled human embryonic stem cells

INTRODUCTION

Human embryonic stem cells (hES) have emerged as a potentially new therapeutic approach for treatment of heart and other diseases applying the concept of regenerative medicine. A method for in vivo visualization and tracking of transplanted hES would increase our understanding of in vivo hES behavior in both experimental and clinical settings. The aim of this study was to evaluate the feasibility of magnetic labeling and visualization of hES with magnetic resonance imaging (MRI).

METHODS

hES were established and expanded according to standard procedures. After expansion, the cells were cultured under feeder free conditions and magnetically labeled by addition of dextran-coated Ferrum-oxide particles (Endorem) to the medium. Accumulation of small particles of iron-oxide (SPIO) in hES was assessed by Prussian blue staining and electron microscopy. For in vitro MRI, the labeled and unlabeled hES were examined in cell solution and after transplantation into explanted mouse heart ( approximately 100,000 cells) on a Bruker Avance DMX 500 vertical magnet at 11.75 T. A multi-slice, multi spin-echo T(2)-weighted images were obtained. For in vivo imaging, the experiments were performed on male Sprague-Dawley using Bruker Biospec 2.35 T magnet. The hES were directly injected ( approximately 500,000 cells) after surgical procedure (thoracotomy) into anterior left ventricular (LV) wall. Multi-slice T(2)-weighted gradient echo images were obtained using cardiac gating.

RESULTS

hES appeared to be unaffected by magnetic labeling and maintained their ability to proliferate and differentiate. No additive agent for membrane permeabilisation was needed for facilitation of intracellular SPIO accumulation. Prussian blue and electron microscopy have revealed numerous iron particles in the cytoplasm of hES. On T(2)-weighted images, the labeled cells have shown well-defined hyopintense areas at the site of injection in anterior LV wall both in vitro and in vivo.

CONCLUSIONS

It is feasible to magnetically label and visualize hES both in vitro and in vivo. MR visualization of magnetically labeled hES may be a valuable tool for in vivo tracking of hES.

Clonal populations of chondrocytes with progenitor properties identified within human articular cartilage

The aim of the present study was to identify and characterize progenitor properties of human articular chondrocytes selected by using agarose suspension culture. In this chondrogenic selective culture condition, about 3.6% of seeded surplus chondrocytes from patients undergoing articular chondrocyte transplantation proliferated and formed cell clusters after 6 weeks. Phase-contrast microscopy and transmission electron microscopy revealed four different types of cell clusters differing in cellular content and matrix production. Based on their morphological features, they were named the homogenous (H), the homogenous matrix (HM), the differentiated matrix (DM) and the differentiated (D) cell clusters. All cell clusters showed positive safranin O staining, and matrix was positive for antibodies detecting type II collagen and aggrecan. The clusters were further demonstrated to express the genes for fibroblast growth factor receptor 3, type IIA collagen and type IIB collagen, while type X collagen was not expressed. After subcloning, the H and HM clusters demonstrated the best proliferative capacity. Chondrocytes from these two cell clusters also showed phenotypic plasticity in chondrogenic, adipogenic as well as osteogenic assays. This study demonstrates that existing subpopulations of cells with chondroprogenitor properties can be isolated from human adult articular cartilage using agarose suspension cultures.

Clonal growth of human articular cartilage and the functional role of the periosteum in chondrogenesis

OBJECTIVE

Clinical cartilage repair with transplantation of cultured chondrocytes, the first described technique introduced in 1994, includes a periosteal membrane but today cells are also implanted without the periosteal combination. The aim of this study was to see if the periosteum had more than a biomechanical function and if the periosteum had a biological effect on the seeded cells tested in an agarose system in which the clonal growth in agarose and the external growth stimulation could be analysed.

METHODS

Four different experiments were used to study the growth of human chondrocytes in agarose and the periosteal influence. Human chondrocytes were isolated and transferred to either primary or secondary agarose culture. After 4 weeks, the total number of clones >50 microm was counted. Cocultures of chondrocytes and periosteal tissue, cultures of chondrocytes with conditioned medium from chondrocytes, periosteal cells and fibroblast were used to study a potential stimulatory effect on growth and different cytokines and growth factors were analysed.

RESULTS

It was found that the human chondrocytes had different growth properties in agarose with the formation of four different types of clones: a homogenous clone without matrix production, a homogenous clone with matrix production, a differentiated clone with matrix production and finally a differentiated clone without matrix production. The periosteum exerted a paracrine effect on cultured chondrocytes in agarose resulting in a higher degree of cloning. The chondrocytes produced significant amounts of interleukin (IL)-6, IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF) and transforming growth factor (TGF)-beta. The periosteum produced significant amounts of IL-6, IL-8 and TGF-beta. Cocultures of chondrocytes and periosteum demonstrated a potentiation of IL-6 and IL-8 release but not of TGF-beta and GM-CSF.

CONCLUSION

Articular chondrocytes are able to form clones of different properties in agarose and the periosteum has a capacity of stimulating chondrocyte clonal growth and differentiation and secretes significant amounts of IL-6, IL-8, GM-CSF and TGF-beta. It may be that the repair of cartilage defects with seeded chondrocytes could benefit from the combination with a periosteal graft. The production of TGF-beta by implanted chondrocytes could influence the chondrogenic cells in the periosteum to start a periosteal chondrogenesis and together with the matrix from implanted chondrocyte production, a repair of cartilaginous appearance may develop; a dual chondrogenic response is possible.

Subchondral bone reaction associated with chondral defect and attempted cartilage repair in goats

Repair of cartilage damage with autologous chondrocyte transplantation (ACT) has become popular in clinical use during the past few years. Although clinical results have mostly been successful, several unanswered questions remain regarding the biological mechanism of the repair process. The aim of this study was to develop a goat model for ACT. The repair was not successful due to the graft delamination, but we characterize the subchondral changes seen after the procedure. A chondral lesion was created in 14 goat knees, operated on 1 month later with ACT, and covered with periosteum or a bioabsorbable poly-L/D-lactide scaffold. After 3 months, only two of the five lesions repaired with ACT showed partly hyaline-like repair tissue, and all lesions (n = 4) with the scaffold failed. Even though the lesions did not extend through the calcified cartilage, the bone volume and collagen organization of bone structure were decreased when assessed by quantitative polarized light microscopy. There was a significant loss of bone matrix and distortion of the trabecular structure of subchondral bone, which extended several millimeters into the bone. The subchondral bone demonstrated strong hyaluronan staining in the bone marrow and cartilaginous areas with signs of endochondral ossification, suggesting structural remodeling of the bone. The goat model used here proved not to be an optimal model for ACT. The changes in subchondral bone may alter the biomechanical properties of the subchondral plate and thus the long-term survival of the repair tissue after ACT.

Phenotypic plasticity of human articular chondrocytes

BACKGROUND

Progenitor cells in mesenchymal tissues are important in the maintenance of tissue homeostasis and regeneration capacity. Articular cartilage is a tissue with a very low capacity for repair. One explanation could be the lack of chondrogenic progenitor cells within the adult tissue. As a test of chondrogenic differentiation potential, we examined the ability of isolated chondrocytes to take on several phenotypic identities within the mesenchymal lineage by applying culture techniques and markers used in the study of the phenotypic plasticity of marrow-derived mesenchymal stem cells (MSCs).

METHODS

Culture-expanded human articular chondrocytes were analyzed for chondrogenic, adipogenic, and osteogenic capacity in defined in vitro culture systems. The osteochondrogenic potential of cells loaded into porous calcium-phosphate ceramic cubes implanted into mice was also determined.

RESULTS

The different assays demonstrated that culture-expanded chondrocytes have the potential to form cartilage in pellet mass cultures, to form adipose cells in dense monolayer cultures, and to form a calcium-rich matrix in an osteogenic assay. In the in vitro assays, a variability of phenotypic plasticity was demonstrated among the donors. In contrast with MSCs, chondrocytes formed cartilage only (and not bone) in the in vivo osteochondrogenic assay.

CONCLUSIONS

These results suggest that, within articular cartilage, there are chondrogenic cells that exhibit a level of phenotypic plasticity that is comparable with that of MSCs. However, there was a difference in the expression of bone in the in vivo assay.

No evidence for the involvement of the multidrug resistance-associated protein and/or the monocarboxylic acid transporter in the intestinal transport of fluvastatin in the rat

Fluvastatin, an amphiphilic anion, shows a nonlinear increase in effective intestinal permeability (P(eff)) with increasing lumenal concentrations in rats. The main objective of this study was to investigate whether or not this observation could be attributed to an efflux-mediated transport by the multidrug resistance-associated protein (MRP). In parallel, we investigated the possible involvement of the monocarboxylic acid transporter (MCT) in the rapid intestinal absorption of fluvastatin. Single-pass perfusions were performed in the ileum and colon of the rat, with and without the presence of well-established inhibitors/substrates for the MRP (probenecid) and the MCT (nicotinic acid). The results suggest that neither the MRP nor the MCT are involved to any significant extent in the absorption process of fluvastatin in the rat intestine. Thus, the previously reported concentration-dependent P(eff) of fluvastatin in these intestinal regions of the rat is probably not attributable to saturation of any efflux mediated by MRP.

Health economics benefits following autologous chondrocyte transplantation for patients with focal chondral lesions of the knee

Autologous chondrocyte transplantation (ACT) for the treatment of cartilage injuries has been in clinical use for several years. Since this new technique is potentially more costly and invasive than traditional conservative therapies, we evaluated the effect of ACT on clinical outcome, absenteeism, disability status, and total direct economic burden in 57 patients with full-thickness chondral lesions of the knee treated between 1987 and 1996. Patients graded good or excellent following ACT in the treatments groups were: femoral condyles (28/33), femoral condyles with anterior cruciate ligament (ACL) repair (5/5), osteochondritis dissecans (7/8), and patellar lesions (9/11). Pre-ACT, 57/57 patients were disabled and post-ACT (mean follow-up 7.3 years) 44/57 had no sickness, 10/57 had minor disability, and 1/57 was disabled. Two of the 57 patients suffered re-injury during the follow-up time. In the 10-year period prior to ACT, the average cost of absenteeism and surgery was SEK 982,457 ($ 122,807) and SEK 47,000 ($ 5,875), respectively, compared to the post-ACT period where both absenteeism and medical costs were dramatically reduced: SEK 9,508 ($ 1,189) and SEK 7,050 ($ 881), respectively. In conclusion, 49 of the 57 patients improved clinically as a result of the ACT treatment. A dramatic cost-saving effect was demonstrated over a projected 10-year period due to reduced absenteeism and disability.

Autologous chondrocytes used for articular cartilage repair: an update

Articular cartilage in adults has a poor ability to self-repair after a substantial injury; however, it is not known whether there is a cartilage resurfacing technique superior to the existing techniques. It is not satisfactory that at the beginning of the new millennium, there still is a lack of randomized studies comparing different cartilage repair techniques and there still is little knowledge of the natural course of a cartilaginous lesion. To date, various articular cartilage resurfacing techniques have the potential to improve the repair of cartilage defects and reduce the patient's disability. One such cartilage repair technique is autologous chondrocyte transplantation combined with a periosteal graft. Since the first patient was operated on in 1987, much interest in cartilage repair and cell engineering has emerged. The experience with autologous chondrocyte transplantation during the past 13 years with in vitro chondrocyte expansion, cartilage harvest, and postoperative biopsy technique is discussed, and the latest followup of 213 consecutive patients in different subgroups with 2 to 10 years followup is presented. The technique gives stable long-term results with a high percentage of good to excellent results (84%-90%) in patients with different types of single femoral condyle lesions, whereas patients with other types of lesions have a lower degree of success (mean, 74%).

Changes in p14(ARF) do not play a primary role in human chondrosarcoma tissues

The locus encoding the tumor suppressor p16 has been found to code for a second, different protein. This protein, p14(ARF), has been shown to protect p53 from degradation. Like p16, its gene is often altered in different cancers. In this study, the first unique exon, exon 1 beta, of p14(ARF), has been studied in 22 chondrosarcoma tissues using polymerase chain reaction, DNA sequencing and methylation-specific polymerase chain reaction. One chondrosarcoma was found to have exon 1 beta homozygously deleted, but neither mutations nor methylations were found in any of the chondrosarcomas. This indicates that genetic changes of p14(ARF) are a rare event in chondrosarcoma.

Estimated prevalences of respiratory symptoms, asthma and chronic obstructive pulmonary disease related to detection rate in primary health care

OBJECTIVE

To assess the prevalence of respiratory symptoms, asthma and chronic obstructive pulmonary disease (COPD), and to relate it to an estimated detection rate in primary health care.

DESIGN

A two-staged study with a cross-sectional survey and a clinical validation.

SETTING

The adult population of Värmland, a county in Sweden.

SUBJECTS

4814 persons completed the survey and 206 the confirmative validation study.

MAIN OUTCOME MEASURES

Prevalence of respiratory symptoms, of asthma and COPD.

RESULTS

More than 40% reported respiratory symptoms. Wheeze was reported by 8.0%, shortness of breath by 11.4% and sputum production by 14.1%. Smoking was more common among women than among men. The prevalence of asthma was 8.2% and COPD 2.1%. Of persons with asthma, 33% were estimated to be undiagnosed, 67% used medication and nearly 60% attended primary health care services.

CONCLUSION

Respiratory symptoms as well as asthma were common in this study and equivalent to earlier findings. The difference between the epidemiologically estimated prevalence of asthma and the lower detection rate in primary health care can be explained by at least three factors: persons who did not seek any care, were underdiagnosed or attended other health care providers.

[Risk factors for low back pain among 1.389 pupils in the 8th and 9th grade. An epidemiologic study]

INTRODUCTION

The aim of this study was to investigate the frequency and severity of low back pain (LBP) in 13-16-year-old pupils in relation to selected factors, such as anthropometry, physical activity, smoking, hypermobility, and tightness of hamstring muscles.

METHODS

The study was designed as a cross-sectional questionnaire-based survey and all the pupils were examined by the school doctor for height, weight, mobility of joints, and general health status.

RESULTS

The lifetime prevalence of non-specific LBP was 58.9% and the one-year prevalence was 50.8% with no differences between the sexes. Recurrent/continuous LBP in a moderate to severe degree was recorded in 19.4% of the school children (182 F, 88 M). This was positively correlated to a female gender, a BMI of more than 25 kg/square meter, competitive sports for boys, poor physical fitness, daily smoking, heavy jobs in leisure time, increased use of the health system, and reduced life quality.

DISCUSSION

Stepwise logistic regression analysis indicates that a female gender, daily smoking, and heavy jobs are important associated factors for severe LBP in adolescents, with an observed probability of 46% if all factors are present. We do not know yet whether these factors have any causal importance for the development of severe LBP.

Alterations in the regulatory pathway involving p16, pRb and cdk4 in human chondrosarcoma

The G1 regulatory pathway involving p16, pRb and cdk4 in the cell cycle has been investigated in human chondrosarcoma. The protein expression of p16, pRb and cdk4 was analyzed by Western blot in cultured cells from eight chondrosarcomas and in two chondrosarcoma cell lines. Both cell lines and one other sample were negative for p16. Moreover, one of the cell lines was pRb-negative and showed a high expression of cdk4 as well. In the other cell line and in three other samples pRb of expected size were detected in addition to a shorter form of the protein. To further investigate the reasons for down-regulation of the p16 protein, the p16-coding gene CDKN2 was analyzed by polymerase chain reaction (PCR), methyl-specific PCR (MSP) and sequencing in all tumor samples as well as in corresponding tumor tissues from three of the samples. The p16-negative samples were all found to have homozygous deletion of CDKN2. Another sample showed partial gene methylation and a heterozygous position in codon 148 was detected in one sample. The same base substitution was also found in two of the tissue samples. Finally, cytogenetic analysis of the samples with homozygously deleted CDKN2 revealed multiple structural abnormalities in all three cases. In conclusion, the p16/pRb/cdk4 pathway may play an important role in the pathogenesis of some chondrosarcomas.

Insulin sensitivity and hemostatic factors in clinically healthy 58-year-old men

The objective of this cross-sectional study was to investigate the relationship between factors of the coagulation- and fibrinolysis systems and insulin sensitivity in 104 clinically healthy, 58-years-old men. Insulin sensitivity (hyperinsulinemic euglycemic clamp) adjusted for lean body mass, the metabolic syndrome according to a suggested definition, and different factors in the coagulation- and fibrinolysis system were determined. Subjects with the metabolic syndrome were characterised by increases in PAI-1 activity, tPA antigen, protein C and protein S and low concentrations of tPA activity. Insulin sensitivity was independently and reversibly associated with PAI-1 (p = 0.014) and directly with tPA activity (p = 0.001). Insulin sensitivity was also significantly negatively associated with protein S and protein C and several components in the metabolic syndrome, however not remaining significant in multivariate analyses. Protein C and protein S were significantly associated with PAI-1 activity, tPA activity (negatively), tPA antigen and antithrombin III. In conclusion, the data indicated that insulin resistance and several of the clustering components in the metabolic syndrome are accompanied by increased plasma concentrations of the anticoagulatory proteins C and S which may represent a mechanism which counteracts the concomitantly occurring hypofibrinolysis.