Bone marrow lesions and joint effusion are strongly and independently associated with weight-bearing pain in knee osteoarthritis: data from the osteoarthritis initiative

OBJECTIVE

It is widely believed that there are multiple sources of pain at a tissue level in osteoarthritis (OA). Magnetic Resonance Images (MRIs) provide a wealth of anatomic information and may allow identification of specific features associated with pain. We hypothesized that in knees with OA, bone marrow lesions (BMLs), synovitis, and effusion would be associated with weight-bearing and (less so with) non-weight-bearing pain independently.

METHODS

In a cross-sectional study of persons with symptomatic knee OA using univariate and multivariate logistic regressions with maximal BML, effusion, and synovitis defined by Boston Leeds Osteoarthritis Knee Score as predictors, and knee pain using weight-bearing and non-weight-bearing Western Ontario and McMaster University OA Index pain questions as the outcome, we tested the association between MRI findings and knee symptoms.

RESULTS

160 participants, mean age 61 (+/-9.9), mean body mass index (BMI) 30.3 (+/-4.7) and 50% female, stronger associations were seen with weight-bearing compared with non-weight-bearing knee pain with adjusted risk ratios (RRs) of weight-bearing knee pain, for increasing maximal BML scores of 1.0 (referent) (maximal BML=0), 1.2, 1.9, and 2.0 (P for trend=0.006). For effusion scores, adjusted RRs of knee pain were 1.0, 1.7, 2.0, and 2.6 (P for trend=0.0004); and for synovitis scores, adjusted ORs were 1.0, 1.4, 1.5, and 1.9 (P for trend=0.22).

CONCLUSION

Cross-sectionally, maximal BML and effusion scores are independently associated with weight-bearing and less so with non-weight-bearing knee pain, supporting the idea that pain in OA is multifactorial. These MRI features should be considered as possible new treatment targets in knee OA.

Change in cartilage morphometry: a sample of the progression cohort of the Osteoarthritis Initiative

OBJECTIVE

The performance characteristics of hyaline articular cartilage measurement on magnetic resonance imaging (MRI) need to be accurately delineated before widespread application of this technology. Our objective was to assess the rate of natural disease progression of cartilage morphometry measures from baseline to 1 year in knees with osteoarthritis (OA) from a subset of participants from the Osteoarthritis Initiative (OAI).

METHODS

Subjects included for this exploratory analysis are a subset of the approximately 4700 participants in the OAI Study. Bilateral radiographs and 3T MRI (Siemans Trio) of the knees and clinical data were obtained at baseline and annually in all participants. 160 subjects from the OAI Progression subcohort all of whom had both frequent symptoms and, in the same knee, radiographic OA based on a screening reading done at the OAI clinics were eligible for this exploratory analysis. One knee from each subject was selected for analysis. 150 participants were included. Using sagittal 3D DESSwe (double echo, steady-state sequence with water excitation) MR images from the baseline and 12 follow-up month visit, a segmentation algorithm was applied to the cartilage plates of the index knee to compute the cartilage volume, normalised cartilage volume (volume normalised to bone surface interface area), and percentage denuded area (total cartilage bone interface area denuded of cartilage).

RESULTS

Summary statistics of the changes (absolute and percentage) from baseline at 1 year and the standardised response mean (SRM), ie, mean change divided by the SD change were calculated. On average the subjects were 60.9 years of age and obese, with a mean body mass index of 30.3 kg/m2. The SRMs for cartilage volume of various locations are: central medial tibia -0.096; central medial femur -0.394; and patella -0.198. The SRMs for normalised cartilage volume of the various locations are central medial tibia -0.044, central medial femur -0.338 and patella -0.193. The majority of participants had a denuded area at baseline in the central medial femur (62%) and central medial tibia (60%). In general, the SRMs were small.

CONCLUSIONS

These descriptive results of cartilage morphometry and its change at the 1-year time point from the first substantive MRI data release from the OAI Progression subcohort indicate that the annualised rates of change are small with the central medial femur showing the greatest consistent change.

Longitudinal study of magnetic resonance imaging and standard X-rays to assess disease progression in osteoarthritis

OBJECTIVE

To investigate, over 1-year, the relationship between X-ray and magnetic resonance imaging (MRI) findings in patients with knee osteoarthritis (OA).

METHODS

Sixty-two osteoarthritic patients (46 women) were followed for 1 year. At baseline and after 1 year, volume and thickness of cartilage of the medial tibia, the lateral tibia and the femur were assessed by MRI. A global score from the multi-feature whole-organ MRI scoring system (WORMS) was calculated for each patient at baseline and after 1 year. This score combined individual scores for articular cartilage, osteophytes, bone marrow abnormality, subchondral cysts and bone attrition in 14 locations. It also incorporated scores for the medial and lateral menisci, anterior and posterior cruciate ligaments, medial and lateral collateral ligaments and synovial distension. Lateral and medial femoro-tibial joint space width (JSW) measurements, performed by digital image analysis, were assessed from fixed-flexion, postero-anterior knee radiographs.

RESULTS

One-year changes in medial femoro-tibial JSW reach 6.7 (20.5) % and changes in medial cartilage volume and thickness reach 0.4 (16.7) % and 2.1 (11.3) %, respectively. Medial femoro-tibial joint space narrowing (JSN) after 1 year, assessed by radiography, was significantly correlated with a loss of medial tibial cartilage volume (r=0.25, P=0.046) and medial tibial cartilage thickness (r=0.28, P=0.025), over the same period. We found also a significant correlation between the progression of the WORMS and radiographic medial JSN over 1 year (r=-0.35, P=0.006). All these results remained statistically significant after adjusting for age, sex and body mass index.

CONCLUSION

This study shows a moderate but significant association between changes in JSW and changes in cartilage volume or thickness in knee joint of osteoarthritic patients.

Osteoarthritis, magnetic resonance imaging, and biochemical markers: a one year prospective study

OBJECTIVE

To investigate the relation between biochemical markers of bone, cartilage, and synovial remodelling and the structural progression of knee osteoarthritis.

METHODS

62 patients of both sexes with knee osteoarthritis were followed prospectively for one year. From magnetic resonance imaging (MRI), done at baseline and after one year, the volume and thickness of cartilage of the femur, the medial tibia, and the lateral tibia were assessed. A whole organ magnetic resonance imaging score (WORMS) of the knee was calculated for each patient at baseline and at the one year visits. This score consists in a validated, semiquantitative scoring system for whole organ assessment of the knee in osteoarthritis using MRI. Biochemical markers (serum hyaluronic acid, osteocalcin, cartilage glycoprotein 39 (YKL-40), cartilage oligomeric matrix protein (COMP), and C-telopeptide of type I collagen (CTX-I), and urine C-telopeptide of type II collagen (CTX-II)) were measured at baseline and after three months.

RESULTS

Baseline markers were not correlated with one year changes observed in cartilage volume and thickness. However, an increase in CTX-II after three months was significantly correlated with a one year decrease in mean thickness of medial tibial and lateral tibial cartilage. Patients in the highest quartile of three month changes in CTX-II experienced a mean loss of 0.07 (0.08) mm of their medial thickness, compared with a mean increase of 0.05 (0.19) mm for patients in the lowest quartile (p = 0.04) Multiple regression analysis showed that high baseline levels of hyaluronic acid are predictive of a worsening in WORMS (p = 0.004).

CONCLUSIONS

These results suggest that a single measurement of serum hyaluronic acid or short term changes in urine CTX-II could identify patients at greatest risk of progression of osteoarthritis.

Analysis of individual human trigeminal ganglia for latent herpes simplex virus type 1 and varicella-zoster virus nucleic acids using real-time PCR

Herpes simplex virus type 1 (HSV-1) and varicella-zoster virus (VZV) establish latent infections in the peripheral nervous system following primary infection. During latency both virus genomes exhibit limited transcription, with the HSV-1 LATs and at least four VZV transcripts consistently detected in latently infected human ganglia. In this study we used real-time PCR quantitation to determine the viral DNA copy number in individual trigeminal ganglia (TG) from 17 subjects. The number of HSV-1 genomes was not significantly different between the left and right TG from the same individual and varied per subject from 42.9 to 677.9 copies per 100 ng of DNA. The number of VZV genomes was also not significantly different between left and right TG from the same individual and varied per subject from 37.0 to 3,560.5 copies per 100 ng of DNA. HSV-1 LAT transcripts were consistently detected in ganglia containing latent HSV-1 and varied in relative expression by >500-fold. Of the three VZV transcripts analyzed, only transcripts mapping to gene 63 were consistently detected in latently infected ganglia and varied in relative expression by >2,000-fold. Thus, it appears that, similar to LAT transcription in HSV-1 latently infected ganglia, VZV gene 63 transcription is a hallmark of VZV latency.

Simian virus 40 late mRNA leader sequences involved in augmenting mRNA accumulation via multiple mechanisms, including increased polyadenylation efficiency

We have examined the contribution of 5' leader sequences to expression directed by the simian virus 40 (SV40) late promoter. These studies showed that addition of sequences which contain the late leader 3' splice site to the late promoter led to an increase in the accumulation of mRNA expressed by the promoter. No other sequences within the leader region, between SV40 positions 334 and 560, exhibited a substantial influence on mRNA accumulation. The increase was due, at least in part, to the creation of a spliceable mRNA transcript, since mutation of either the 5' or 3' splice site could attenuate the effect. However, sequences at or near the 3' splice site appeared to play a more important role than did the 5' splice site in bringing about this increase. In many instances, mutation of the 3' splice site also led to the accumulation of extended transcripts, whereas mutation of the 5' splice site did not produce this result in any instance. Analysis of these extended transcripts showed that they retained sequences normally lost upon cleavage and polyadenylation. This finding suggested that mutation of the 3' splice site sequence led to decreases in the efficiency of polyadenylation. We propose that the SV40 late leader sequences positively contribute to expression of the viral late genes by increasing mRNA accumulation via multiple mechanisms, including the enhancement of pre-mRNA polyadenylation efficiency.

Translational control of synthesis of simian virus 40 late proteins from polycistronic 19S late mRNA

The simian virus 40 (SV40) 19S late mRNA is polycistronic, encoding multiple late proteins: agnoprotein, VP2, and VP3. We constructed a chloramphenicol acetyltransferase (CAT) transient expression vector in which the SV40 sequences between nucleotides 5171 and 1046 (via the SV40 origin of replication and including the late promoter) were inserted 5' to the cat gene; therefore, the AUG for CAT expression occurs after the AUGs for agnoprotein, VP2, and VP3. CAT enzyme activity assayed after transfection of these constructions indicates the level of CAT AUG utilization and, therefore, can be used as a measure of the ability of prior AUGs to intercept scanning ribosomes. Specifically, deletions and point mutations of the viral AUGs resulted in increased CAT enzyme activity owing to increased utilization of the downstream CAT AUG. To compare a variety of mutants, we used the levels of increase to calculate the translational efficiency of the viral AUGs. Some of our data agree with predictions of the modified scanning model (MSM). Little variation in downstream CAT AUG utilization was noted regardless of whether the VP2 AUG (in a weak MSM sequence context) was intact or removed. Hence, a scanning ribosome may easily bypass it. Similar analysis of the VP3 AUG (in a favorable MSM sequence context) demonstrated that it could efficiently intercept ribosomes prior to the downstream AUG. Overall, these data indicate that the structure of the 19S late mRNA and the relative efficiency of translational start codon utilization can account for the VP3/VP2 ratio found in infected cells. The agnoprotein reading frame, depending on how the mRNA precursor is spliced, is either not contained in the mRNA or is terminated near the VP2 AUG. Under these conditions, the ability of the agnoprotein AUG to block downstream CAT AUG utilization was found to be minimal in our assay. However, we directly tested the blocking ability of the agnoprotein AUG under conditions in which the reading frame terminated well after the CAT AUG. Although the agnoprotein AUG lies in a very good sequence context, this direct analysis showed that it interfered minimally with utilization of the CAT AUG when under the control of the SV40 late promoter. However, expected high levels of interference were regained when the late promoter was replaced with the Rous sarcoma virus long terminal repeat.(ABSTRACT TRUNCATED AT 400 WORDS)

Complementation studies of isovaleric acidemia and glutaric aciduria type II using cultured skin fibroblasts

Using cultured skin fibroblasts, we studied the heterogeneity of inborn errors of leucine metabolism such as isovaleric acidemia (IVA), glutaric aciduria type II (GA II), and multiple carboxylase deficiency (MC). We first developed a simple macromolecular-labeling test to measure the ability of cells to oxidize [1-14C]isovaleric acid in situ in culture. Cells from two different lines were fused using polyethylene glycol, and the ability of the heterokaryons to oxidize [1-14C]isovaleric acid was tested by the macromolecular-labeling test. The MC line complemented with all 10 IVA lines tested; heterokaryons showed 99 +/- 68% more activity than the unfused mixture of component cells. GA II/IVA heterokaryons exhibited poor growth, but when the culture remained confluent, the GA II cells complemented with all six IVA lines tested, showing a 71 +/- 41% increase in activity. The relatively large standard deviations are due to a few experiments in which significant enhancement of macromolecular-labeling test activity was not observed upon fusion, but significant complementation was clearly observed in repeats of the same combinations. These results are consistent with our previous findings, which indicated that the decreased ability of GA II cells to oxidize isovaleryl-CoA involves a defective electron-transporting system rather than a defective isovaleryl-CoA dehydrogenase. IVA/IVA heterokaryons showed no complementation in any combination tested, indicating no detectable heterogeneity in isovaleric acidemia. This finding indicates that the same gene is mutated in all IVA lines. Previous results indicated that this gene codes for isovaleryl-CoA dehydrogenase.