The combination of the biomarkers urinary C-terminal telopeptide of type II collagen, serum cartilage oligomeric matrix protein, and serum chondroitin sulfate 846 reflects cartilage damage in hemophilic arthropathy

OBJECTIVE

Hemophilic arthropathy, with characteristics of inflammatory (rheumatoid arthritis) and degenerative (osteoarthritis) joint damage, occurs at an early age, is associated with minor comorbidity, and is restricted to 3 pairs of large joints. The aim of this study was to determine whether commonly used serum and/or urinary biomarkers of cartilage and bone turnover for which assay kits are commercially available are associated with the severity of joint damage in patients with various degrees of hemophilic arthropathy and, thus, whether this disease could be useful in the identification and evaluation of such biomarkers.

METHODS

Blood and urine samples were collected from 36 patients with various degrees of hemophilic arthropathy. Commercially available assays for the most frequently investigated serum and urine biomarkers were performed: urinary C-terminal telopeptide of type I collagen (CTX-I), urinary CTX-II, serum CTX-I, serum CTX-II, serum cartilage oligomeric matrix protein (COMP), serum cartilage cleavage products C1,2C and C2C, and serum chondroitin sulfate 846 (CS-846). Radiographs of the ankles, knees, and elbows in all patients were evaluated for the degree of joint damage according to the Pettersson score, which is based on cartilage and periarticular bone changes and is specific for hemophilic arthropathy.

RESULTS

Urinary CTX-II, serum C1,2C, and serum CS-846 levels correlated with the overall Pettersson score and with the joint space narrowing component. Regression analysis showed that combined indexes of different markers increased the degree of correlation for the combination of urinary CTX-II, serum COMP, and serum CS-846. Bone-specific markers (urinary/serum CTX-I and serum C1,2C) did not correlate with specific bone-related items of the Pettersson score (osteoporosis and erosions).

CONCLUSION

These results support the idea that a combination of biomarkers relates significantly better to the severity of joint damage than do individual biomarkers. The combination of urinary CTX-II, serum COMP, and serum CS-846 correlated best with the degree of arthropathy. Because of its specific characteristics and restricted involvement, hemophilic arthropathy may prove useful in the screening of newly developed biomarkers of joint damage.

Towards understanding the functional difference between the two PsbO isoforms in Arabidopsis thaliana--insights from phenotypic analyses of psbo knockout mutants

The extrinsic PsbO subunit of the water-oxidizing photosystem II (PSII) complex is represented by two isoforms in Arabidopsis thaliana, namely PsbO1 and PsbO2. Recent analyses of psbo1 and psbo2 knockout mutants have brought insights into their roles in photosynthesis and light stress. Here we analyzed the two psbo mutants in terms of PsbOs expression pattern, organization of PSII complexes and GTPase activity. Both PsbOs are present in wild-type plants, and their expression is mutually controlled in the mutants. Almost all PSII complexes are in the monomeric form not only in the psbo1 but also in the psbo2 mutant grown under high-light conditions. This results either from an enhanced susceptibility of PSII to photoinactivation or from malfunction of the repair cycle. Notably, the psbo1 mutant displays such problems even under growth-light conditions. These results together with the finding that PsbO2 has a threefold higher GTPase activity than PsbO1 have significance for the turnover of the PSII D1 subunit in Arabidopsis.

Gadolinium contrast agent is of limited value for magnetic resonance imaging assessment of synovial hypertrophy in hemophiliacs

PURPOSE

To examine the influence of different doses of gadolinium contrast agent on synovial enhancement, to compare magnetic resonance imaging (MRI) findings of synovial hypertrophy and radiographic joint changes in hemophiliacs, and to investigate the value of gadolinium in MRI assessment of synovial hypertrophy in hemophiliacs using dynamic MRI and MRI scoring.

MATERIAL AND METHODS

Twenty-one hemophiliacs on prophylactic factor treatment without recent bleeds were subjected to radiography and gadolinium contrast-enhanced dynamic and static MRI of the knee using a standard dose of 0.1 mmol/kg b.w. gadoteridol. In 17 of the patients, the MRI procedure was repeated after a triple dose of gadoteridol.

RESULTS

MRI findings of synovial hypertrophy were significantly correlated with Pettersson radiographic scores. In 19 of the 21 MRI investigated joints, administration of contrast agent did not alter the result of the evaluation of synovial hypertrophy.

CONCLUSION

The optimal time interval for volume assessment of synovial hypertrophy after injection of gadolinium contrast agent is dose dependent. Hemophiliacs without recent bleeds have minor to abundant synovial hypertrophy in joints with pronounced radiographic changes. Dynamic MRI is not useful for evaluating hemophilic arthropathy, and gadolinium contrast agent is not routinely indicated for MRI scoring of joints in hemophiliacs.

The Arabidopsis PsbO2 protein regulates dephosphorylation and turnover of the photosystem II reaction centre D1 protein

The extrinsic photosystem II (PSII) protein of 33 kDa (PsbO), which stabilizes the water-oxidizing complex, is represented in Arabidopsis thaliana (Arabidopsis) by two isoforms. Two T-DNA insertion mutant lines deficient in either the PsbO1 or the PsbO2 protein were retarded in growth in comparison with the wild type, while differing from each other phenotypically. Both PsbO proteins were able to support the oxygen evolution activity of PSII, although PsbO2 was less efficient than PsbO1 under photoinhibitory conditions. Prolonged high light stress led to reduced growth and fitness of the mutant lacking PsbO2 as compared with the wild type and the mutant lacking PsbO1. During a short period of treatment of detached leaves or isolated thylakoids at high light levels, inactivation of PSII electron transport in the PsbO2-deficient mutant was slowed down, and the subsequent degradation of the D1 protein was totally inhibited. The steady-state levels of in vivo phosphorylation of the PSII reaction centre proteins D1 and D2 were specifically reduced in the mutant containing only PsbO2, in comparison with the mutant containing only PsbO1 or with wild-type plants. Phosphorylation of PSII proteins in vitro proceeded similarly in thylakoid membranes from both mutants and wild-type plants. However, dephosphorylation of the D1 protein occurred much faster in the thylakoids containing only PsbO2. We conclude that the function of PsbO1 in Arabidopsis is mostly in support of PSII activity, whereas the interaction of PsbO2 with PSII regulates the turnover of the D1 protein, increasing its accessibility to the phosphatases and proteases involved in its degradation.

Subsequent events to GTP binding by the plant PsbO protein: structural changes, GTP hydrolysis and dissociation from the photosystem II complex

Besides an essential role in optimizing water oxidation in photosystem II (PSII), it has been reported that the spinach PsbO protein binds GTP [C. Spetea, T. Hundal, B. Lundin, M. Heddad, I. Adamska, B. Andersson, Proc. Natl. Acad. Sci. U.S.A. 101 (2004) 1409-1414]. Here we predict four GTP-binding domains in the structure of spinach PsbO, all localized in the beta-barrel domain of the protein, as judged from comparison with the 3D-structure of the cyanobacterial counterpart. These domains are not conserved in the sequences of the cyanobacterial or green algae PsbO proteins. MgGTP induces specific changes in the structure of the PsbO protein in solution, as detected by circular dichroism and intrinsic fluorescence spectroscopy. Spinach PsbO has a low intrinsic GTPase activity, which is enhanced fifteen-fold when the protein is associated with the PSII complex in its dimeric form. GTP stimulates the dissociation of PsbO from PSII under light conditions known to also release Mn(2+) and Ca(2+) ions from the oxygen-evolving complex and to induce degradation of the PSII reaction centre D1 protein. We propose the occurrence in higher plants of a PsbO-mediated GTPase activity associated with PSII, which has consequences for the function of the oxygen-evolving complex and D1 protein turnover.

Reliability and construct validity of the compatible MRI scoring system for evaluation of haemophilic knees and ankles of haemophilic children. Expert MRI working group of the international prophylaxis study group

We tested the reliability and construct validity of the Compatible magnetic resonance imaging (MRI) scale for the evaluation of haemophilic knees and ankles and compared the diagnostic performance of MRI and plain film radiographs. Sagittal and coronal gradient-echo 1.5-T MR images of knees (n=22) and ankles (n=23) were obtained from boys (age range 4-16 years; mean 11 years) in two centres (Toronto, n=26; Europe, n=19). The MR images were independently read by four blinded radiologists on two occasions. Number of previous joint bleedings and laboratory level of severity of haemophilia were the reference standards for imaging assessment. Both components of the MRI scale demonstrated high inter- and intrareader intraclass correlation coefficients (progressive (P) scale, 0.91 and 0.94; additive (A) scale, 0.81 and 0.92 respectively). The correlation between the osteochondral domain of the MRI scale and patient's age was moderate. Otherwise, correlations between A- and P-scales and clinical laboratory measurements were weak. The areas under the curve (AUCs) used for discrimination of disease severity were similar for the A- and P-scales (AUCs used for mild disease, A-scale, 0.72+/-0.07; P-scale, 0.69+/-0.08; P=0.23; AUCs for severe disease, A-scale, 0.93+/-0.05; P-scale, 0.87+/-0.08; P=0.05). No differences were noted between the AUCs of the MRI and radiographic scales used for discrimination of late osteoarticular changes; MRI scales performed better for discrimination of early changes. In conclusion, both MRI scales demonstrated excellent reliability, poor convergent validity, and moderate and excellent validity for discrimination of mild and severe diseases respectively. Compared with radiographic scores, the MRI scales performed better for discrimination of early osteoarticular changes.

Recent developments in clinimetric instruments

Assessment of impairment and function is essential in order to monitor joint status and evaluate therapeutic interventions in patients with haemophilia. The improvements in the treatment of haemophilia have required the development of more sensitive tools to detect the more minor dysfunctions that may now be apparent. This paper outlines some of the recent developments in this field. The Haemophilia Joint Health Score (HJHS) provides a systematic and robust measure of joint impairment. The MRI Scoring System has been designed to provide a comprehensive scoring system combining both progressive and additive scales. The Functional Independence Score for Haemophilia (FISH) has been developed to assess performance of functional activities and can be used in conjunction with the Haemophilia Activities List (HAL) which provides a self report measure of function. It is recommended that both measures are evaluated as these tools measure different constructs. Further refinement and testing of the psychometric properties of all of these tools is in progress. More widespread use of these tools will enable the sharing of data across the world so promoting best practice and ultimately enhancing patient care.

Evolution of the imaging tests in hemophilia with emphasis on radiography and magnetic resonance imaging

Even before the discovery of X-rays in 1895 attempts were being made to classify the joint destruction that occurs in hemophilic arthropathy. The advent of radiography added impetus to the search for the optimum classification system. Subsequent attempts have included advanced imaging methods, especially magnetic resonance imaging (MRI). Because of its high spatial resolution and ability to visualize soft tissue abnormalities, MRI is ideally suited as the best way to classify arthropathy. A literature search was carried out to document and list all the imaging methods for hemophilic arthropathy that have been published up to the present. All published classification systems are discussed and listed in tables. MRI has superior imaging capability and will probably become the most important modality for radiological classification of hemophilic arthropathy in the future.

MRI scores of ankle joints in children with haemophilia--comparison with clinical data

Fifty-six ankle joints in 38 haemophilic boys were investigated by magnetic resonance imaging (MRI) and the findings were classified according to both the Denver- and the European scoring schemes. The different MRI scores were compared with each other and with clinical data on number of joint bleeds and the orthopaedic joint score. MRI changes that were more advanced than a small effusion were found in 33 (59%) of the ankles and osteochondral changes were observed in 20 (36%). The total number of bleeds in individual ankles ranged from 0 to 80 (mean: 11). The orthopaedic joint score was 0 for 49 ankles and ranged from one to four for seven ankles. There was a significant and strong correlation between the assessment results obtained with the two MRI scoring methods (correlation coefficients ranged from 0.80 to 0.95, P < 0.001), and both types of MRI scores were weakly but significantly correlated with the clinical data on the number of joint bleeds and the orthopaedic joint score (correlation coefficients: 0.32-0.39, P < 0.01 or P < 0.05). MRI is useful for evaluating early joint changes in patients with haemophilia. The European scoring method differentiates the arthropathic changes further than the Denver scale does, but the two different scoring methods have similar correlation to the number of joint bleeds and the orthopaedic joint score.

Reliability of progressive and additive MRI scoring systems for evaluation of haemophilic arthropathy in children: Expert MRI Working Group of the International Prophylaxis Study Group

Effective treatment of haemophilic arthropathy requires a detailed evaluation of joint integrity. Methodological assessment of magnetic resonance imaging (MRI) scores are needed to assure reproducibility of measurements when comparing results of clinical trials conducted in different centres. We compared the reliability of two MRI scoring systems for assessment of haemophilic arthropathy: one progressive system that displays the most severe change and one additive system that depicts osteochondral and soft tissue-related changes. A total of 47 1.5 T MRI examinations of knees (n = 21) and ankles (n = 26) of 42 haemophilic boys, age range, 22 months to 18 years, performed at different centres (Toronto, n = 20, Europe, n = 12 and Denver, n = 15) were independently reviewed by four radiologists at two occasions. Twenty-two examinations were from children <9 years and 25 from children >/=9. Sagittal and coronal gradient-echo (MPGR, 3D FLASH with fat saturation, GRASS) images were obtained. The MRI examinations of the ankle and knee studies presented with osteochondral abnormalities in 38.5% and 23.8% of the cases respectively. The two scoring systems demonstrated an excellent inter-reader [progressive, 0.88; additive (A, e, s and h components), 0.86] and intra-reader [progressive, 0.92; additive (A, e, s and h components), 0.93] reliability using intraclass correlation coefficients (ICCs). Although ICCs were slightly higher for knees when compared with ankles, and for older children when compared with younger children, all values fell within excellent inter- and intra-reader reliability categories. The two MRI scoring systems demonstrated a comparable reliability. This result constitutes the basis for further development of a combined MRI scoring system for assessment of haemophilic arthropathy, which incorporates progressive and additive components.

Compatible scales for progressive and additive MRI assessments of haemophilic arthropathy

The international MRI expert subgroup of the International Prophylaxis Study Group (IPSG) has developed a consensus for magnetic resonance imaging (MRI) scales for assessment of haemophilic arthropathy. A MRI scoring scheme including a 10 step progressive scale and a 20 step additive scale with identical definitions of mutual steps is presented. Using the progressive scale, effusion/haemarthrosis can correspond to progressive scores of 1, 2, or 3, and synovial hypertrophy and/or haemosiderin deposition to 4, 5, or 6. The progressive score can be 7 or 8 if there are subchondral cysts and/or surface erosions, and it is 9 or 10 if there is loss of cartilage. Using the additive scale, synovial hypertrophy contributes 1-3 points to the additive score and haemosiderin deposition contributes 1 point. For osteochondral changes, 16 statements are evaluated as to whether they are true or false, and each true statement contributes 1 point to the additive score. The use of these two compatible scales for progressive and additive MRI assessments can facilitate international comparison of data and enhance the accumulation of experience on MRI scoring of haemophilic arthropathy.

Physical therapy and imaging outcome measures in a haemophilia population treated with factor prophylaxis: current status and future directions

Routine infusions of factor VIII to prevent bleeding, known as prophylaxis, and other intensive therapies are being more broadly applied to patients with haemophilia. These therapies differ widely in replacement product usage, cost, frequency of venous access and parental effort. In order to address residual issues relating to recommendations, implementation, and evaluations of prophylaxis therapy in persons with haemophila, a multinational working group was formed and called the International Prophylaxis Study Group (IPSG). The group was comprised of haemophilia treaters actively involved in studies of prophylaxis from North America and Europe. Two expert committees, the Physical Therapy (PT) Working Group and the Magnetic Resonance Imaging (MRI) Working Group were organized to critically assess existing tools for assessment of joint outcome. These two committees independently concluded that the WFH Physical Examination Scale (WFH PE Scale) and the WFH X-ray Scale (WFH XR Scale) were inadequately sensitive to detect early changes in joints. New scales were developed based on suggested modifications of the existing scales and called the Haemophilia Joint Health Score (HJHS) and the International MRI Scales. The new scales were piloted. Concordance was measured by the intra-class correlation coefficient of variation. Reliability of the HJHS was excellent with an inter-observer co-efficient of 0.83 and a test-retest value of 0.89. The MRI study was conducted using both Denver and European scoring approaches; inter-reader reliability using the two approaches was 0.88 and 0.87; test-retest reliability was 0.92 and 0.93. These new PT and MRI scales promise to improve outcome assessment in children on early preventive treatment regimens.

A new magnetic resonance imaging scoring method for assessment of haemophilic arthropathy

In a European multicentre study, 39 ankles in 28 haemophilic boys were investigated by magnetic resonance imaging (MRI). A new MRI score was developed in the format A(e:s:h) for evaluating haemophilic arthropathy. This scheme provides high resolution and allows separation of different pathological components. The factor A is calculated as the sum of scores for subchondral cysts (maximum value 6), irregularity/erosion of subchondral cortex (maximum 4) and chondral destruction (maximum 6); e, s and h, respectively, represent effusion/haemarthrosis, synovial hypertrophy and haemosiderin deposition, and they are separately evaluated on a scale of 0-4. Working independently, two radiologists scored the 39 ankles twice using both this new 'European' scoring method and a previously published 'Denver' scoring scheme. Final classification was achieved by consensus. The reproducibility of the readings was assessed, and for both scoring methods the results indicated good or moderate intraobserver agreement, and good, moderate or fair interobserver agreement. These findings suggest that MRI can be useful for semiquantitative evaluation of haemophilic arthropathy, providing the examination is performed according to an appropriate protocol, and the images are evaluated by specially trained radiologists.

Are digital images good enough? A comparative study of conventional film-screen vs digital radiographs on printed images of total hip replacement

The aim of this study was to evaluate the inter- and intra-observer variability and to find differences in diagnostic safety between digital and analog technique in diagnostic zones around hip prostheses. In 80 patients who had had a total hip replacement (THR) for more than 2 years, a conventional image and a digital image were taken. Gruen's model of seven distinct regions of interest was used for evaluations. Five experienced radiologists observed the seven regions and noted in a protocol the following distances: stem-cement; cement-bone; and stem-bone. All images were printed on hard copies and were read twice. Weighted kappa, kappa(w), analyses were used. The two most frequently loosening regions, stem-cement region 1 and cement-bone region 7, were closely analyzed. In region 1 the five observers had an agreement of 86.75-97.92% between analog and digital images in stem-cement, which is a varied kappa(w) 0.29-0.71. For cement-bone region 7 an agreement of 87.21-90.45% was found, which is a varied kappa(w) of 0.48-0.58. All the kappa values differ significantly from nil. The result shows that digital technique is as good as analog radiographs for diagnosing possible loosening of hip prostheses.

Multiple evidence for nucleotide metabolism in the chloroplast thylakoid lumen

The apparatus of photosynthetic energy conversion in chloroplasts is quite well characterized with respect to structure and function. Light-driven electron transport in the thylakoid membrane is coupled to synthesis of ATP, used to drive energy-dependent metabolic processes in the stroma and the outer surface of the thylakoid membrane. The role of the inner (luminal) compartment of the thylakoids has, however, remained largely unknown although recent proteomic analyses have revealed the presence of up to 80 different proteins. Further, there are no reports concerning the presence of nucleotides in the thylakoid lumen. Here, we bring three lines of experimental evidence for nucleotide-dependent processes in this chloroplast compartment. (i) The thylakoid lumen contains a protein of 17.2 kDa, catalyzing the transfer of the gamma-phosphate group from ATP to GDP, proposed to correspond to the nucleoside diphosphate kinase III. (ii) The 33-kDa subunit of photosystem II, bound to the luminal side of the thylakoid membrane and associated with the water-splitting process, can bind GTP. (iii) The thylakoid membrane contains a nucleotide transport system that is suggested to be associated with a 36.5-kDa nucleotide-binding protein. Our results imply, against current dogmas, that the thylakoid lumen contains nucleotides, thereby providing unexpected aspects on this chloroplast compartment from a metabolic and regulatory perspective and expanding its functional significance beyond a pure bioenergetic function.

[Munchausen syndrome by proxy. Child abuse by falsification of symptoms]

Münchausen syndrome by proxy (MSbP) is a potentially lethal form of child abuse. Mortality rates around 10 percent have been reported. A knowledge of the characteristics of MSbP is needed in order to reveal the diagnosis and to handle the management correctly. Swedish experience is in accordance with international reports.

Passive knee muscle moment arms measured in vivo with MRI

OBJECTIVE: To determine moment arm lengths from seven knee muscles and the patellar tendon. The knee muscles were the biceps femoris, semitendinosus, semimembranosus, gracilis, sartorius, and the lateral and medial gastrocnemius muscles. DESIGN: The moment arms were calculated based on MRI measurements. BACKGROUND: Moment arm lengths of different muscles with respect to the joint centre of rotation (CR) or the centre of the contact point between joint surfaces are necessary basic data for biomechanical models predicting joint load. METHODS: Ten male and seven female subjects participated. Using a 1.5 Tesla magnetic resonance imaging system, 3-dimensional coordinates of relevant points were recorded from a 3-D volume reconstruction of the right knee at knee flexion angles of 0, 30 and 60 degrees. Muscular moment arms were calculated in both the sagittal and frontal planes. The recordings were all made during passive mode, which means that no muscular contraction was performed. RESULTS: All muscles except the lateral gastrocnemius showed statistically significant differences (P<0.05) of moment arm lengths between gender in the frontal plane. All muscles except biceps femoris and sartorius showed significant differences (P<0.05) of moment arm lengths between gender in the sagittal plane. Most muscles also showed a linear or quadratic trend of changing moment arms with varying knee angle. CONCLUSIONS: Our results indicate that for most biomechanical analyses involving knee muscles, gender- and angle-specific moment arms should be used.

Radiation dose reduction in computed skeletal radiography. Effect on image quality

PURPOSE

To evaluate the effect of radiation dose reduction on image ++quality in computed musculoskeletal radiography and determine optimal exposure range.

MATERIAL AND METHODS

In 11 corpses, 1 hand and 1 hip were examined with film-screen radiography, and a series of computed radiographs was obtained using exactly the same technique except for the exposure, which was 100, 50, 25, 12.5, 6.25, and 1.56% of the mAs numbers used for the film-screen images. The computed hip radiographs were processed in 2 different ways, one simulating the film-screen images and one using contrast enhancement. Four radiologists reviewed the images regarding the following parameters: cortical bone, trabecular bone, joint space, and soft tissue, giving each a diagnostic quality rating on a scale from 1 to 5. The median and mean values were found for the pooled results.

RESULTS

For the hands, the computed radiographs were ranked inferior to the film-screen images for all parameters except soft tissue, where the computed radiographs scored higher. The computed images with 50 and 25% exposure were ranked equal to the 100% ones. The quality rating slowly declined with lower exposures. For the hips, the 100 and 50% computed radiographs were generally similar to or slightly better than the film-screen images. The decline was somewhat faster than for the hands. The contrast-enhanced hip images scored less than the nonenhanced images at any given exposure for all parameters except soft tissue, where the contrast-enhanced images scored better at all exposures. The difference between nonenhanced and enhanced images became less at the lower exposures.

CONCLUSION

Lowering the exposure in computed musculoskeletal radioagrphy below the level of film-screen radiography is feasible, especially in the peripheral skeleton. Contrast enhancement seems to be valuable only in the evaluation of soft-tissue structures.