Buoyancy-corrected gravimetric analysis of lightly loaded filters

Numerous sources of uncertainty are associated with the gravimetric analysis of lightly loaded air filter samples (< 100 microg). The purpose of the study presented here is to investigate the effectiveness and limitations of air buoyancy corrections over experimentally adjusted conditions of temperature (21-25 degrees C) and relative humidity (RH) (16-60% RH). Conditioning (24 hr) and weighing were performed inside the Archimedes M3 environmentally controlled chamber. The measurements were performed using 20 size-fractionated samples of resuspended house dust loaded onto Teflo (PTFE) filters using a Micro-Orifice Uniform Deposit Impactor representing a wide range of mass loading (7.2-3130 microg) and cut sizes (0.056-9.9 microm). By maintaining tight controls on humidity (within 0.5% RH of control setting) throughout pre- and postweighing at each stepwise increase in RH, it was possible to quantify error due to water absorption: 45% of the total mass change due to water absorption occurred between 16 and 50% RH, and 55% occurred between 50 and 60% RH. The buoyancy corrections ranged from -3.5 to +5.8 microg in magnitude and improved relative standard deviation (RSD) from 21.3% (uncorrected) to 5.6% (corrected) for a 7.2 microg sample. It is recommended that protocols for weighing low-mass particle samples (e.g., nanoparticle samples) should include buoyancy corrections and tight temperature/humidity controls. In some cases, conditioning times longer than 24 hr may be warranted.

Performance of detecting IgM antibodies against enterovirus 71 for early diagnosis

Enterovirus 71 (EV71) infection is more likely to induce severe complications and mortality than other enteroviruses. Methods for detection of IgM antibody against EV71 had been established for years, however, the performance of the methods in the very early diagnosis of EV71 infection had not been fully evaluated, which is especially meaningful because of the short incubation period of EV71 infection. In this report, the performance of an IgM anti-EV71 assay was evaluated using acute sera collected from 165 EV71 infected patients, 165 patients infected with other enteroviruses, and more than 2,000 sera from healthy children or children with other infected diseases. The results showed a 90% sensitivity in 20 patients who were in their first illness day, and similar sensitivity remained till 4 days after onset. After then the sensitivity increased to 95% to 100% for more than one month. The specificity of the assay in non-HFMD children is 99.1% (95% CI: 98.6–99.4), similar as the 99.9% specificity in healthy adults. The cross-reaction rate in patients infected with other non-EV71 enteroviruses was 11.4%. In conclusion, the data here presented show that the detection of IgM anti-EV71 by ELISA affords a reliable, convenient, and prompt diagnosis of EV71 infection.

A novel immunoassay for PreS1 and/or core-related antigens for detection of HBsAg variants

A novel immunoassay that detects simultaneously hepatitis B virus (HBV) PreS1 and/or core-related antigens was developed and evaluated for its potential for detecting hepatitis B surface antigen (HBsAg) variants. The detection limits of the assay was 10(2.9+/-0.5)copies/mL (mean+/-SD) for HBsAg-positive sera with different genotypes, and 10(3.5+/-1.2)copies/mL for HBsAg variants sera. The specificity of the assay was 99.9% (95% CI: 99.7-99.9%, 4551 healthy individuals). The sensitivities were 93.9% (95% CI: 92.8-94.9%), 59.3% (95% CI: 38.7-77.6%) and 80% (95% CI: 44.4-97.5%) in three independent groups which include: 2065 hepatitis patients, 27 patients with occult hepatitis B and 10 HBsAg variants, respectively. In addition, a novel premature stop code mutation at position 112 of HBsAg was observed in two patients with chronic hepatitis B with different genotypes.

A comparison of dedicated 1.0 T extremity MRI vs large-bore 1.5 T MRI for semiquantitative whole organ assessment of osteoarthritis: the MOST study

OBJECTIVE

To date semiquantitative whole-organ scoring of knee osteoarthritis (OA) relies on 1.5 Tesla (T) Magnetic resonance imaging (MRI) systems. Less costly 1.0 T extremity systems have been introduced that offer superior patient comfort, but may have limitations concerning field-of-view and image quality. The aim of this study was to compare semi-quantitative (SQ) scoring on a 1.0 T system using 1.5 T MRI as the standard of reference.

METHODS

The Multicenter Osteoarthritis Study (MOST) is a longitudinal study of individuals who have or are at high risk for knee OA. A sample of 53 knees was selected in which MRI was performed on a 1.0 T extremity system as well as on a 1.5 T scanner applying a comparable sequence protocol. MRIs were read according to the Whole Organ Magnetic Resonance Imaging Score (WORMS) score. Agreement was determined using weighted kappa statistics. Sensitivity, specificity and accuracy were assessed using the 1.5 T readings as the reference standard. In addition the number of non-readable features was assessed.

RESULTS

Agreement (w-kappa) for seven main WORMS features (cartilage, bone marrow lesions (BMLs), osteophytes, meniscal damage and extrusion, synovitis, effusion) ranged between 0.54 (synovitis) and 0.75 (cartilage). Sensitivity ranged between 68.1% (meniscal damage) and 88.1% (effusion). Specificity ranged between 63.6% (effusion) and 96.4% (BMLs). Although the overall rate of non-readable features was very low, it was higher for the 1.0 T system (1.9% vs 0.2%).

CONCLUSIONS

Semiquantitative whole organ scoring can be performed using a 1.0 T peripheral scanner with a moderate to high degree of agreement and accuracy compared to SQ assessment using a 1.5 T whole body scanner. Our results are comparable to the published inter- and intra observer exercises obtained from 1.5 T systems. Sensitivity to change of longitudinal scoring was not evaluated in this cross-sectional design and should be investigated in future validation studies.

Does cartilage volume or thickness distinguish knees with and without mild radiographic osteoarthritis? The Framingham Study

OBJECTIVES

To examine whether the quantity of cartilage or semiquantitative scores actually differ in knees with mild radiographic osteoarthritis compared with knees without osteoarthritis.

METHODS

Framingham Osteoarthritis Study participants had knee tibiofemoral magnetic resonance imaging-based measurements of cartilage. Using three-dimensional FLASH-water excitation sequences, cartilage volume, thickness and subregional cartilage thickness were measured and cartilage scored semiquantitatively (using the whole-organ magnetic resonance imaging score; WORMS). Using weight-bearing radiographs, mild osteoarthritis was defined as Kellgren/Lawrence (K/L) grade 2 and non-osteoarthritis as K/L grade 0. Differences between osteoarthritis and non-osteoarthritis knees in median cartilage measurements were tested using the Wilcoxon rank sum test.

RESULTS

Among 948 participants (one knee each), neither cartilage volume nor regional thickness were different in mild versus non-osteoarthritis knees. In mild osteoarthritis, cartilage erosions in focal areas were missed when cartilage was quantified over large regions such as the medial tibia. For some but not all subregions of cartilage, especially among men, cartilage thickness was lower (p<0.05) in mild osteoarthritis than non-osteoarthritis knees. Because semiquantitative scores captured focal erosions, median WORMS scores were higher in mild osteoarthritis than non-osteoarthritis (all p<0.05). In moderate/severe osteoarthritis (K/L grades 3 or 4), osteoarthritis knees had much lower cartilage thickness and higher WORMS scores than knees without osteoarthritis.

CONCLUSIONS

In mild osteoarthritis, the focal loss of cartilage is missed by quantitative measures of cartilage volume or thickness over broad areas. Regional cartilage volume and thickness (eg, medial tibia) are not different in mild osteoarthritis versus non-osteoarthritis. Subregional thickness may be decreased in mild osteoarthritis. Semiquantitative scoring that assesses focal cartilage damage differentiates mild osteoarthritis from non-osteoarthritis.

High systemic bone mineral density increases the risk of incident knee OA and joint space narrowing, but not radiographic progression of existing knee OA: the MOST study

OBJECTIVES

Previous studies suggest that high systemic bone mineral density (BMD) is associated with incident knee osteoarthritis (OA) defined by osteophytes but not with joint space narrowing (JSN), and are inconsistent regarding BMD and progression of existing OA. The association of BMD with incident and progressive tibiofemoral OA was tested in a large prospective study of men and women aged 50-79 years with or at risk for knee OA.

METHODS

Baseline and 30-month weight-bearing posteroanterior and lateral knee radiographs were scored for Kellgren-Lawrence (K-L) grade, JSN and osteophytes. Incident OA was defined as the development of K-L grade > or =2 at follow-up. All knees were classified for increases in grade of JSN and osteophytes from baseline. The association of gender-specific quartiles of baseline BMD with risk of incident and progressive OA was analysed using logistic regression, adjusting for covariates.

RESULTS

The mean (SD) age of 1754 subjects was 63.2 (7.8) years and body mass index was 29.9 (5.4) kg/m(2). In knees without baseline OA, higher femoral neck and whole body BMD were associated with an increased risk of incident OA and increases in grade of JSN and osteophytes (p<0.01 for trends); adjusted odds were 2.3-2.9-fold greater in the highest compared with the lowest BMD quartiles. In knees with existing OA, progression was not significantly related to BMD.

CONCLUSIONS

In knees without OA, higher systemic BMD was associated with a greater risk of the onset of JSN and K-L grade > or =2. The role of systemic BMD in early knee OA pathogenesis warrants further investigation.

Cartilage loss occurs in the same subregions as subchondral bone attrition: a within-knee subregion-matched approach from the Multicenter Osteoarthritis Study

OBJECTIVE

By magnetic resonance imaging (MRI), subchondral bone attrition (SBA) can be seen in early osteoarthritis (OA), but the significance of this is unknown. We therefore evaluated whether SBA was associated with cartilage loss within the same subregion of the knee.

METHODS

The Multicenter Osteoarthritis Study is a cohort of individuals who have or are at high risk for knee OA. At baseline and 30 months, participants' knee MRIs were graded using the Whole-Organ Magnetic Resonance Imaging Score in the 10 subregions of the tibiofemoral joint for cartilage morphology and SBA. We conducted analyses within a knee to eliminate between-person confounding, using an M:N (cases:controls) matched case-control approach with the 10 subregions of a person's knee forming a matched set. Cases within a knee were defined as subregions with cartilage loss, while controls were subregions in that same knee without cartilage loss. We evaluated the association of cartilage loss over 30 months with the presence of baseline SBA in the same subregion within that knee using conditional logistic regression.

RESULTS

SBA was associated with an odds ratio of 7.5 (95% confidence interval 5.6-9.9, P < 0.0001) for cartilage loss in the same subregion compared with subregions without any baseline SBA in our sample of 459 knees from participants, 64% of whom were women, with a mean age of 63 years and a mean body mass index of 30.5 kg/m(2).

CONCLUSION

SBA is strongly associated with cartilage loss within the same subregion of a knee. SBA may directly influence overlying cartilage loss or serve as a marker of an area undergoing great compressive stress and in which cartilage loss is inevitable.

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.

Can anatomic alignment measured from a knee radiograph substitute for mechanical alignment from full limb films?

OBJECTIVES

To examine whether categories of anatomic alignment (varus, neutral, valgus) measured from knee X-rays agree with similar categories of mechanical alignment from the full limb film and whether varus anatomic malalignment predicts medial joint space loss on knee X-rays as well as varus mechanical alignment.

METHODS

We used data from the Osteoarthritis Initiative (OAI) (full limb and flexed knee X-rays) to examine agreement of anatomic and mechanical alignment and data from Boston Osteoarthritis of the Knee Study (BOKS) to evaluate the association of full limb mechanical alignment vs knee X-ray anatomic alignment with joint space loss. A 4 degree offset was used to correct for the more valgus angulation of the anatomic alignment.

RESULTS

Of 143 subjects whose knee X-rays and full limb films were publicly released from the OAI, the agreement of varus, neutral and valgus alignment was only moderate (kappa=0.43, P<0.001). In BOKS, varus mechanical and anatomic alignments measured from full limb and knee X-rays respectively both predicted a high risk of medial joint space loss vs neutral alignment--for mechanical alignment, odds ratio (OR)=4.82 [95% confidence interval (CI) 1.93, 12.00] and for anatomic alignment OR=4.25 (95% CI 2.08, 8.72).

CONCLUSIONS

While agreement of alignment from knee X-ray to full limb film was only moderate, varus malalignment measured from a flexed knee predicted the likelihood of progression well. Flexed knee alignment may be more relevant to knee osteoarthritis (OA) risk than that of a fully extended knee, but a measurement of alignment from a short limb is an imperfect surrogate for full limb alignment.

Effects of Polarization on the Extents and Kinetics of Adsorption of Ionic and Neutral Aromatic Heterocyclics Exhibiting Orientation Transitions at a Porous C Electrode

Comparative investigations of the adsorption and electrosorption of the heterocyclic compounds, pyridine, 1,4-pyrazine and 1-quinoline, and their orientation behaviours in an high specific-area C-cloth/H2O interphase, directly related to the replacement of preadsorbed and field-oriented solvent (H2O) molecules by oriented adsorbates themselves, have been carried out by means of in situ UV spectrophotometry conducted under positive or negative electric polarization at the C-cloth as an electrode. Surface charge, dipole moment of the adsorbate, polarization mode, acidity of the solution (leading to cation formation) and hydrophilic/hydrophobic properties of the adsorbed molecules in relation to the solvent (H2O vs. non-aqueous) are found to have important influences on these processes and hence govern the experimentally measurable extents and rates of their adsorption. The adsorption and orientation effects were indicated by evaluation of surface-dipole potential changes represented by Esin and Markov (EM)-type effects. Different adsorption and orientation processes amongst the three adsorbates, together with the possible rearrangement of the adsorbed molecules, were revealed by changes of the observed EM effects. The preferred adsorption/electrosorption behaviour arises by either “combined adsorption” (CAD) (i.e. combination of adsorption on open-circuit with electrosorption upon subsequent polarization) or by “alternate polarization electrosorption” (APE) (i.e. electrosorption by periodically reversed direction of polarization, between positive and negative, in one adsorption experiment). Negative-current polarization in a single transient also led to similar results for effective adsorptive removal of 1-quinoline from aqueous solution. Major differences of adsorption arise between neutral pyridine and its cation in acidic solution, including the effect of electrode polarization.

Contrast-enhanced MRI of subchondral cysts in patients with or at risk for knee osteoarthritis: the MOST study

OBJECTIVE

The aim of the study was (1) to evaluate contrast enhancement patterns of subchondral cysts on magnetic resonance imaging and (2) to discuss possible radiological explanations of cyst enhancement based on existing theories of subchondral cyst formation in osteoarthritis.

MATERIALS AND METHODS

The Multicenter Osteoarthritis Study (MOST) is a NIH-funded longitudinal observational study for individuals who have or are at high risk for knee osteoarthritis. All subjects with available non-enhanced and contrast-enhanced MRI were included. The tibiofemoral and patellofemoral joints were divided in 14 subregions. The presence and size of subchondral cysts and bone marrow edema-like lesions (BMLs) were scored semiquantitatively in each subregion on non-contrast-enhanced MRI from 0 to 3. Enhancement of subchondral cysts was evaluated on contrast-enhanced MRI as grade 0 (absent), grade 1 (partial enhancement), or grade 2 (full enhancement). The adjacent articular cartilage was scored in each subregion on non-enhanced MRI as grade 0 (intact), grade 1 (partial thickness loss), or grade 2 (full thickness loss).

RESULTS

Four hundred knees were included (1 knee per person, 5600 subregions). Subchondral cysts were detected in 260 subregions (4.6%). After intravenous contrast administration, 245 cysts (94.2%) showed full enhancement, 12 (4.6%) showed partial enhancement and 3 (1.2%) showed no enhancement. Enhancing BMLs were found in 237 (91.2%) subregions containing cysts, which were located adjacent or in the middle of BMLs. In 121 subregions (46.5%) having cysts, no adjacent full thickness cartilage loss was detected.

CONCLUSION

Most subchondral cysts demonstrated full or partial contrast enhancement, and were located adjacent or in the midst of enhancing BMLs. As pure cystic lesions are not expected to enhance on MRI, the term "subchondral cyst-like bone marrow lesion" might be appropriate to describe these lesions.

The association of bone attrition with knee pain and other MRI features of osteoarthritis

OBJECTIVE

To determine whether bone attrition (flattening or depression of the subchondral bone) was associated with the presence and severity of knee pain and to evaluate the coexistence of attrition and other MRI features likely associated with pain.

METHODS

Participants in the Framingham Osteoarthritis Study, a community cohort unselected for OA, answered questions about knee pain and underwent knee x rays and MRI. Attrition, bone marrow lesions (BMLs) and effusions were scored on MRI using the WORMS scale. We assessed attrition in knees with and without pain, and using logistic regression examined its association with pain adjusting for age, gender, Kellgren-Lawrence (K-L)grade, BMI, BML and effusion. We also explored the relation between attrition, pain severity and nocturnal pain.

RESULTS

Attrition (Grade >2) was present in 28% (167/592) of painful knees and in 10% (106/1035) of nonpainful knees (adjusted OR 1.6 (95% CI 1.1 to 2.2)). Of knees with OA (n=368), 74% had pain if attrition was present and 58% if it was absent (adjusted OR 1.2 (95%CI 0.7 to 2.0)). Of knees without OA (n=1222), pain was reported in 39% of knees with attrition and in 27%without it (adjusted OR 2.1 (95% CI 1.1 to 4.0)). We found no association between either attrition/pain severity or attrition/nocturnal pain. Attrition often co-occurred with other OA features associated with pain such as BMLs and effusions.

CONCLUSIONS

Attrition was associated independently with knee pain. Unlike knees without OA, the association was lost in OA knees where other pathological features that may cause pain also coexisted.

The association of meniscal damage with joint effusion in persons without radiographic osteoarthritis: the Framingham and MOST osteoarthritis studies

OBJECTIVE

To assess the cross-sectional association between meniscal status and joint effusion on magnetic resonance imaging (MRI) in knees without radiographic osteoarthritis (OA).

DESIGN

Knees without OA (Kellgren/Lawrence grade 0) from the Framingham and MOST studies were examined by MRI. Meniscal status was assessed with a score of 0-4 in the anterior horn/body/posterior horn of the medial/lateral meniscus and effusion was assessed using a score of 0-3. The odds ratios (ORs) of joint effusion in those with meniscal damage were estimated using a logistic regression model. A subanalysis was performed for knees without MRI-detected cartilage damage.

RESULTS

Of 1368 knees, 296 (21.6%) showed meniscal pathology in at least one subregion. Effusion was present in 133 (44.9%) of knees with meniscal damage vs 328 (30.6%) in those without meniscal damage. The adjusted OR of effusion in a knee with meniscal damage was 1.8, 95% confidence intervals (CI) [1.4, 2.4]. The OR of effusion for the group with meniscal pathology in two compartments was 5.4, 95% CI [2.1, 14.3]. For knees without any cartilage lesions but with meniscal damage in any compartment the OR was 2.3, 95% CI [1.1, 4.5].

CONCLUSIONS

Knees without OA but with meniscal pathology exhibit joint effusion to a significantly higher degree than knees without meniscal damage. The association persists for knees without cartilage damage. The prevalence of effusion is further increased when present in two compartments. Concomitant occurrence of synovial activation and meniscal damage contributes to understanding the pathophysiology of early degenerative joint disease.

Is obesity a risk factor for progressive radiographic knee osteoarthritis?

OBJECTIVE

To examine whether obesity increases the risk of progression of knee osteoarthritis (OA).

METHODS

We used data from the Multicenter Osteoarthritis Study, a longitudinal study of persons with or at high risk of knee OA. OA was characterized at baseline and 30 months using posteroanterior fixed-flexion radiographs and Kellgren/Lawrence (K/L) grading, with alignment assessed on full-extremity films. In knees with OA at baseline (K/L grade 2 or 3), progression was defined as tibiofemoral joint space narrowing on the 30-month radiograph. In knees without OA at baseline (K/L grade 0 or 1), incident OA was defined as the development of radiographic OA at 30 months. Body mass index (BMI) at baseline was classified as normal (<25 kg/m(2)), overweight (25-<30 kg/m(2)), obese (30-<35 kg/m(2)), and very obese (>or=35 kg/m(2)). The risk of progression was tested in all knees and in subgroups categorized according to alignment. Analyses were adjusted for age, sex, knee injury, and bone density.

RESULTS

Among the 2,623 subjects (5,159 knees), 60% were women, and the mean +/- SD age was 62.4 +/- 8.0 years. More than 80% of subjects were overweight or obese. At baseline, 36.4% of knees had tibiofemoral OA, and of those, only one-third were neutrally aligned. Compared with subjects with a normal BMI, those who were obese or very obese were at an increased risk of incident OA (relative risk 2.4 and 3.2, respectively [P for trend < 0.001]); this risk extended to knees from all alignment groups. Among knees with OA at baseline, there was no overall association between a high BMI and the risk of OA progression; however, an increased risk of progression was observed among knees with neutral but not varus alignment. The effect of obesity was intermediate in those with valgus alignment.

CONCLUSION

Although obesity was a risk factor for incident knee OA, we observed no overall relationship between obesity and the progression of knee OA. Obesity was not associated with OA progression in knees with varus alignment; however, it did increase the risk of progression in knees with neutral or valgus alignment. Therefore, weight loss may not be effective in preventing progression of structural damage in OA knees with varus alignment.

Collaborative distributed scheduling approaches for wireless sensor network

Energy constraints restrict the lifetime of wireless sensor networks (WSNs) with battery-powered nodes, which poses great challenges for their large scale application. In this paper, we propose a family of collaborative distributed scheduling approaches (CDSAs) based on the Markov process to reduce the energy consumption of a WSN. The family of CDSAs comprises of two approaches: a one-step collaborative distributed approach and a two-step collaborative distributed approach. The approaches enable nodes to learn the behavior information of its environment collaboratively and integrate sleep scheduling with transmission scheduling to reduce the energy consumption. We analyze the adaptability and practicality features of the CDSAs. The simulation results show that the two proposed approaches can effectively reduce nodes' energy consumption. Some other characteristics of the CDSAs like buffer occupation and packet delay are also analyzed in this paper. We evaluate CDSAs extensively on a 15-node WSN testbed. The test results show that the CDSAs conserve the energy effectively and are feasible for real WSNs.

Change in MRI-detected subchondral bone marrow lesions is associated with cartilage loss: the MOST Study. A longitudinal multicentre study of knee osteoarthritis

OBJECTIVES

To describe the natural history of subchondral bone marrow lesions (BMLs) in a sample of subjects with knee osteoarthritis (OA) or at risk of developing it. Additionally, to examine the association of change in BMLs from baseline to 30-month follow-up with the risk of cartilage loss in the same subregion at follow-up.

METHODS

1.0 T MRI was performed using proton density-weighted, fat-suppressed sequences. BML size and cartilage status were scored in the same subregions according to the WORMS system. Subregions were categorised based on comparison of baseline and follow-up BML status. A logistic regression model was used to assess the association of change in BML status with cartilage loss over 30 months using stable BMLs as the reference group.

RESULTS

395 knees were included. 66% of prevalent BMLs changed in size; 50% showed either regression or resolution at follow-up. The adjusted odds ratios (95% confidence intervals) of cartilage loss in the same subregion at follow-up for the different groups were 1.2 (0.5 to 1.6) for regressing BMLs, 0.9 (0.5 to 1.6) for resolving BMLs, 2.8 (1.5 to 5.2) for progressing BMLs, 0.2 (0.1 to 0.3) for subregions with no BMLs at baseline and follow-up and 3.5 (2.1 to 5.9) for newly developing BMLs. BML size at baseline was associated with risk of subsequent cartilage loss.

CONCLUSIONS

The majority of pre-existing BMLs decreased in size at follow-up. Absence of BMLs was associated with a decreased risk of cartilage loss, while progressing and new BMLs showed a high risk of cartilage loss in the same subregion.

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.

Effects of dietary phospholipid level in cobia (Rachycentron canadum) larvae: growth, survival, plasma lipids and enzymes of lipid metabolism

A study was conducted to determine the effects of dietary phospholipid (PL) levels in cobia (Rachycentron canadum) larvae with regard to growth, survival, plasma lipids and enzymes of lipid metabolism. Fish with an average weight of 0.4 g were fed diets containing four levels of PL (0, 20, 40 and 80 g kg(-1)dry matter: purity 97%) for 42 days. Final body weight (FBW), weight gain (WG) and survival ratio were highest in the 8% PL diet group and mortality was highest in PL-free diet group. We examined the activities of lipoprotein lipase (LPL) and hepatic lipase (HL) in liver, lecithin-cholesterolacyltransferase (LCAT) in plasma as well as plasma lipids and lipoprotein. LCAT activity showed a decrease of more than two-fold in PL-supplemented diet groups compared with the PL-free diet group. HL activity was highest in the 8% PL diet group and the other three groups showed no difference. LPL activity was significantly higher in the PL-supplemented diet groups than in the PL-free diet group. The dietary intervention significantly increased plasma phospholipids and total cholesterol (TC) levels, and the higher free cholesterol (FC) level contributed to the TC level. However, the fish fed PL exhibited a significantly decreased plasma triglyceride (TG) level. The lipoprotein fractions were also affected significantly by the PL. The PL-supplemented diet groups had significantly higher high-density lipoprotein (HDL) compared with the PL-free diet group, but showed a marked decrease in very low-density lipoprotein (VLDL). The results suggested that PL could modify plasma lipoprotein metabolism and lipid profile, and that the optimal dietary PL level may well exceed 80 g kg(-1) for cobia larvae according to growth and survival.

On-site quantification of re-entry ratio of ventilation exhausts in multi-family residential buildings and implications

In the worldwide spread of Severe Acute Respiratory Syndrome (SARS) in 2003, cluster of cases occurred in a number of large high-rise residential building blocks, especially in Hong Kong. In this study, we examined one of the most likely virus-spread mechanisms, which is related to the inter-flat or inter-zonal airflow through open-windows caused by buoyancy effects. Dual tracer gases of CO2 and SF6 are employed simultaneously to quantify the amount of the exhaust air coming out of the upper part of the window of a floor that re-enters the lower part of the open-window at the immediate upper floor. It was found that the room air could contain up to 7% of the exhaust air from the lower floor, and this occurs at low wind conditions with a combination of indoor-outdoor temperature difference. The results can well explain the earlier governmental finding that DNA strings of SARS Corono-Virus were detected within the sampled deposits on the window sills of the upper floors of the two index patients' flats. The preliminary and yet alarming conclusion may be that, in high-rise buildings, windows flush with a flat façade can be a major route for the vertical spread of pathogen-containing aerosols.

PRACTICAL IMPLICATIONS

The confirmation of the transmission route can have a number of implications to both building design and infectious disease control. With respect to the former, considerations should be given to minimize the inter-flat airflow via windows flush with façade for high-rise buildings with natural ventilation; and with respect to the latter, more targeted and earlier intervention can be implemented in case of any highly infectious disease outbreaks.

Meniscal damage associated with increased local subchondral bone mineral density: a Framingham study

OBJECTIVE

Because menisci and the medial vs lateral tibial plateau bone mineral density ratio (M:L BMD) are associated with loading within the knee, we postulated there to be an association between compartment-specific meniscal damage and M:L BMD. We hypothesized that knees with higher M:L BMD, consistent with increased medial subchondral BMD, would be associated with medial meniscal damage, and lower ratios with lateral meniscal damage.

METHODS

We conducted a cross-sectional study evaluating participants in the Framingham Osteoarthritis Cohort having magnetic resonance images (MRIs), BMDs, and x-rays of the knee. Medial and lateral meniscal damage were defined on MRI. We performed a logistic regression with medial meniscal damage as the outcome testing M:L BMD groups as predictor variables. We adjusted for age and sex; we used generalized estimating equations (GEE) to adjust for correlation between knees. Identical analyses were performed evaluating lateral meniscal damage.

RESULTS

When evaluating the relation of M:L BMD to medial meniscal damage, the odds ratios (ORs) of prevalent medial meniscal damage from lowest to highest quartile of M:L BMD were 1.0 (referent), 1.9, 2.4 and 8.9, P for trend <0.0001. When evaluating the relation of M:L BMD to lateral meniscal damage, the ORs of prevalent lateral meniscal damage from lowest to highest quartile of M:L BMD were 1.0 (referent), 0.3, 0.2, and 0.2, P for trend = 0.001.

CONCLUSIONS

Meniscal damage is associated with higher regional tibial BMD in the same compartment. Our findings highlight the close relationship between meniscal integrity and regional tibial subchondral BMD.

Knee alignment differences between Chinese and Caucasian subjects without osteoarthritis

OBJECTIVE

Despite the lower prevalence of obesity (a known risk factor for osteoarthritis (OA)), the prevalence of lateral tibiofemoral OA is higher in Chinese communities compared with Caucasian communities. One potential explanation is the difference in knee alignment between the two populations. We measured various knee alignment indices among Chinese and Caucasians and assessed whether these indices were different between the two racial groups.

METHODS

We selected participants from the Framingham Osteoarthritis Study (FOA) and the Beijing Osteoarthritis Study (BOA), all without knee OA (Kellgren & Lawrence grade <2). Bilateral, fully extended anteroposterior knee radiographs were measured for the following angles in both knees: the anatomic axis (AA), the condylar angle (CA), the tibial plateau angle and the condylar-plateau angle (CP). We compared the mean of each measurement between the two racial groups adjusting for age and body mass index using linear regression and stratified by sex.

RESULTS

The mean AA, CA and CP were significantly different in the BOA compared with the FOA. For women, the mean AA and CA were significantly more valgus in BOA subjects, while in men, the mean AA and CP were more valgus in BOA subjects.

CONCLUSIONS

There are significant differences in knee morphology between Chinese and Caucasian cohorts, which result in a more valgus alignment of the distal femur in Chinese. This would serve to shift the mechanical loading towards the lateral compartment, and provide a possible explanation why Chinese have a higher prevalence of lateral tibiofemoral OA.

Integrin alphanvbeta6 acts as a prognostic indicator in gastric carcinoma

AIMS

To investigate the relationships between integrin alphanubeta6 expression and the clinical-pathological features of gastric carcinoma and whether integrin alphanubeta6 can act as a prognostic indicator in gastric carcinoma.

MATERIALS AND METHODS

We generated the microarray of 300 human gastric carcinoma specimens, and used the method of immunohistochemistry to investigate the expression of alphanubeta6 in them and the relationships between the expression of alphanubeta6 and the clinical-pathological features of the tumours. Meanwhile, we retrospectively analysed the relationship between alphanubeta6 expression and the survival times of the patients.

RESULTS

The expression of alphanubeta6 was detected in 36.7% of gastric carcinomas, and the expression was associated with Lauren type, differentiation, N stage and TNM stage of the tumours (the P values were 0.004, 0.035, 0.024 and 0.001, respectively). The Kaplan-Meier plot showed that patients who were alphanubeta6 negative had much longer survival times than those who were alphanubeta6 positive (P<0.0001). The survival estimates showed a striking difference in median survival between the negative and positive alphanubeta6 expression patients, especially in early stage tumours. Univariate analysis indicated that significant factors for prognosis included alphanubeta6 expression, differentiation, TNM stage, T stage, N stage, M stage and R classification (R0: potentially curative resection; R1: had residual microscopic disease after resection; R2: had residual macroscopic disease after resection), whereas in multivariate analysis using the Cox regression model, only alphanubeta6 expression, M stage, TNM stage and R classification retained significance for prognosis.

CONCLUSIONS

Positive alphanubeta6 expression in gastric carcinoma is linked to significantly reduced survival times and, even more important, is that its value as a prognostic marker is significant for early stage tumours.

The association between patella alignment and knee pain and function: an MRI study in persons with symptomatic knee osteoarthritis

OBJECTIVE

The aim of the study was to examine the association between patellofemoral (PF) alignment (using standard magnetic resonance imaging (MRI) images of extended knees) and knee pain and function.

DESIGN

Subjects were recruited to participate in a natural history study of symptomatic knee osteoarthritis, called the Boston Osteoarthritis of the Knee Study (BOKS). The association of predictive variable (patellar alignment in sagittal and transverse planes) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and function were examined using a linear regression model while adjusting for age, sex, body mass index (BMI), Center for Epidemiologic Studies Depression Scale (CES-D) score and Kellgren and Lawrence score.

RESULTS

Increasing trochlear angle (TA) was associated with both WOMAC (P=0.06) pain and WOMAC function subscale (P=0.04). Increasing lateral patellar title angle (LPTA) and decreasing bisect offset (increasing lateral subluxation) appeared to be associated with increasing WOMAC pain. However, no such an association was observed for other predictors.

CONCLUSIONS

The findings of the present study suggest that increasing TA is associated with increased functional impairment. Other measures of PF malalignment were not significantly associated with either knee pain or functional impairment.

The association between patellar alignment and patellofemoral joint osteoarthritis features--an MRI study

OBJECTIVE

The aim of our study was to evaluate the association between patellar alignment (using standard MRI images of extended knees) and MRI indices of patellofemoral (PF) osteoarthritis (OA) features.

METHODS

In this cross-sectional observational study, subjects were recruited to participate in the Boston Osteoarthritis of the Knee Study (BOKS). The association of patellar alignment [patellar length ratio (PLR), sulcus angle (SA), lateral patellar tilt angle (LPTA) and bisect offset (BO)] with measures of PF OA [cartilage morphology and bone marrow lesion (BML) in the medial and lateral PF compartment] were examined using a logistic regression model while adjusting for age, sex and BMI.

RESULTS

Study sample comprised 126 males (mean age 68.0, BMI 31.2) and 87 females (mean age 64.7, BMI 31.6). All measurements of patellar alignment were statistically significantly associated with cartilage morphology and BML in the lateral compartment of PF joint. PLR and SA were significantly associated with medial cartilage loss. With increasing PLR there was an increased prevalence of lateral and medial cartilage loss as well as of lateral BML. Increasing SA was positively associated with increased lateral and medial cartilage loss and lateral BML. LPTA range was negatively associated with lateral cartilage loss and BML. More laterally displaced patella (higher BO) was associated with increased lateral cartilage loss and BML.

CONCLUSIONS

The results of our study clearly indicated that patellar alignment is associated with manifestations of PF OA such as cartilage thickness loss and BML.

Role of ventilation in airborne transmission of infectious agents in the built environment - a multidisciplinary systematic review

There have been few recent studies demonstrating a definitive association between the transmission of airborne infections and the ventilation of buildings. The severe acute respiratory syndrome (SARS) epidemic in 2003 and current concerns about the risk of an avian influenza (H5N1) pandemic, have made a review of this area timely. We searched the major literature databases between 1960 and 2005, and then screened titles and abstracts, and finally selected 40 original studies based on a set of criteria. We established a review panel comprising medical and engineering experts in the fields of microbiology, medicine, epidemiology, indoor air quality, building ventilation, etc. Most panel members had experience with research into the 2003 SARS epidemic. The panel systematically assessed 40 original studies through both individual assessment and a 2-day face-to-face consensus meeting. Ten of 40 studies reviewed were considered to be conclusive with regard to the association between building ventilation and the transmission of airborne infection. There is strong and sufficient evidence to demonstrate the association between ventilation, air movements in buildings and the transmission/spread of infectious diseases such as measles, tuberculosis, chickenpox, influenza, smallpox and SARS. There is insufficient data to specify and quantify the minimum ventilation requirements in hospitals, schools, offices, homes and isolation rooms in relation to spread of infectious diseases via the airborne route. PRACTICAL IMPLICATION: The strong and sufficient evidence of the association between ventilation, the control of airflow direction in buildings, and the transmission and spread of infectious diseases supports the use of negatively pressurized isolation rooms for patients with these diseases in hospitals, in addition to the use of other engineering control methods. However, the lack of sufficient data on the specification and quantification of the minimum ventilation requirements in hospitals, schools and offices in relation to the spread of airborne infectious diseases, suggest the existence of a knowledge gap. Our study reveals a strong need for a multidisciplinary study in investigating disease outbreaks, and the impact of indoor air environments on the spread of airborne infectious diseases.

Cigarette smoking and the risk for cartilage loss and knee pain in men with knee osteoarthritis

OBJECTIVE

To examine the effects of smoking on cartilage loss and pain at the knee in individuals with knee osteoarthritis.

METHODS

159 men with symptomatic knee osteoarthritis who participated in a 30-month, prospective, natural history study of knee osteoarthritis were examined. The more symptomatic knee was imaged using magnetic resonance imaging (MRI) at baseline, and again at 15 and 30 months of follow-up. Cartilage was scored using the Whole-Organ MRI Score semiquantitative method at the medial and lateral tibiofemoral joints and at the patellofemoral joint. At baseline and follow-up visits, the severity of knee pain was assessed using a Visual Analogue Scale pain score (0-100 mm).

RESULTS

Among the 159 men, 19 (12%) were current smokers at baseline. Current smokers were younger (mean (standard deviation (SD)) age 62 (9) v 69 (9) years) and leaner (mean (SD) body mass index (BMI): 28.9 (3.2) v 31.3 (4.8) kg/m(2)) than men who were not current smokers. When adjusted for age, BMI and baseline cartilage scores, men who were current smokers were found to have an increased risk for cartilage loss at the medial tibiofemoral joint (odds ratio (OR) 2.3, 95% confidence interval (CI) 1.0 to 5.4) and the patellofemoral joint (OR 2.5, 95% CI 1.1 to 5.7). Current smokers also had higher adjusted pain scores at baseline (60.5 v 45.0, p<0.05) and at follow-up (59.4 v 44.3, p<0.05) than men who were not current smokers.

CONCLUSIONS

Men with knee osteoarthritis who smoke sustain greater cartilage loss and have more severe knee pain than men who do not smoke.

Preparation of His-tagged armored RNA phage particles as a control for real-time reverse transcription-PCR detection of severe acute respiratory syndrome coronavirus

Armored RNA has been increasingly used as both an external and internal positive control in nucleic acid-based assays for RNA virus. In order to facilitate armored RNA purification, a His6 tag was introduced into the loop region of the MS2 coat protein, which allows the exposure of multiple His tags on the surface during armored RNA assembly. The His-tagged armored RNA particles were purified to homogeneity and verified to be free of DNA contamination in a single run of affinity chromatography. A fragment of severe acute respiratory syndrome coronavirus (SARS-CoV) genome targeted for SARS-CoV detection was chosen for an external positive control preparation. A plant-specific gene sequence was chosen for a universal noncompetitive internal positive control preparation. Both controls were purified by Co2+ affinity chromatography and were included in a real-time reverse transcription-PCR assay for SARS-CoV. The noncompetitive internal positive control can be added to clinical samples before RNA extraction and enables the identification of potential inhibitive effects without interfering with target amplification. The external control could be used for the quantification of viral loads in clinical samples.

The ratio of medial to lateral tibial plateau bone mineral density and compartment-specific tibiofemoral osteoarthritis

INTRODUCTION

Bone is thought to play an important role in osteoarthritis (OA) pathophysiology. Our aim was to look at specific features of OA and their relation to the ratio of medial:lateral tibial plateau bone mineral density (M:L BMD Ratio).

METHODS

We examined our research question in the Framingham OA Study Cohort. All participants had BMDs and weight-bearing plain radiographs of the knees (2002-2005). M:L BMD Ratios were calculated using BMD from medial and lateral regions in the tibial plateau. Knee x-rays were read for osteophytes (OSTs), joint space narrowing (JSN), and sclerosis (Osteoarthritis Research Society International (OARSI) scoring system). Knees were classified as having medial and/or lateral JSN if they had JSN >or=1 in the medial and/or lateral tibiofemoral compartments, respectively. Medial and/or lateral OSTs were defined as medial and/or lateral tibial and/or femoral OSTs >or=2, respectively. Medial sclerosis and lateral sclerosis were defined as medial and lateral tibial sclerosis >or=1, respectively. We performed a logistic regression with medial JSN as the outcome and with M:L BMD Ratio groups as predictor variables, using the median group as the referent. Analyses were adjusted for age, sex, and body mass index (BMI). Generalized estimating equations were used to adjust for correlation between knees. Identical analyses were performed with medial OSTs, medial sclerosis, lateral JSN, lateral OSTs, and lateral sclerosis as the outcomes.

RESULTS

Mean age of 1612 subjects (3048 knees) was 63.9 (Standard Deviation (SD)+/-8.9), 56% were women, and mean BMI was 28.5 (SD+/-5.5). M:L BMD Ratio was positively associated with medial JSN (P for linear trend <0.0001) and negatively associated with lateral JSN (P for linear trend <0.0001). The relations of the ratio with medial and lateral OSTs were j-shaped with P for quadratic trends <0.0001. There were also strong associations between M:L BMD Ratio and compartment-specific sclerosis (P for linear trends <0.0001) with most knees with medial and lateral sclerosis being in the highest and lowest M:L BMD Ratio groups, respectively.

CONCLUSION

In summary, the extremes of the M:L BMD Ratio are strongly associated with individual radiographic features of OA. These findings add to existing evidence supporting the importance of understanding bone in OA pathophysiology.

Detection of Escherichia coli O157 using equal-length double-stranded fluorescence probe in a real-time polymerase chain reaction assay

BACKGROUND

Enterohemorrhagic Escherichia coli (E. coli) O157 is a dangerous pathogen, which causes bloody diarrhea and severe hemolytic uremic syndrome (HUS). Although several assay systems based on real-time polymerase chain reaction (PCR) have been integrated to detect this pathogen, most of them are not specific. We report a real-time quantitative PCR method targeting rfbE, a gene specifically expressed in E. coli O157. This method can therefore be used to diagnose enterohemorrhagic Escherichia coli (E. coli) O157.

METHODS

A nucleic acid based diagnostic assay system, combining equal-length double-stranded fluorescence probe technique and real-time PCR, was developed to detect E. coli O157. This assay system take advantage of the highly conserved rfbE O-antigen synthesis gene, and a pair of fluorescence-quenching probes complementary to rfbE gene were used in a real-time PCR to quantify the presence of the pathogen.

RESULTS

The specificity of the diagnostic method was assessed by comparing test results on 14 different related pathogens including common E. coli, enteroinvasive Escherichia coli (EIEC), Salmonella, Shigella and E. coli O157. The detection limit of the method was determined using 10-fold serial dilutions of an E. coli O157 standard sample, and as few as 1.49 x 10(3) CFU/ml could be detected. All E. coli with serotype O157, which expresses rfbE gene, were positive in this assay, while all other species without rfbE gene expression were negative.

CONCLUSIONS

By combining equal-length double-stranded fluorescence probe technique and real-time PCR, we have developed a simple, rapid, specific and sensitive method to detect E. coli O157.

Lack of association between chondrocalcinosis and increased risk of cartilage loss in knees with osteoarthritis: Results of two prospective longitudinal magnetic resonance imaging studies

OBJECTIVE

To evaluate the relationship between chondrocalcinosis and the progression of knee osteoarthritis (OA) using longitudinal magnetic resonance imaging (MRI) assessments.

METHODS

Longitudinal knee MRIs were obtained in the Boston OA Knee Study (BOKS) and in the Health, Aging and Body Composition (Health ABC) Study. Chondrocalcinosis was determined as present or absent on baseline knee radiographs. Cartilage morphology was graded on paired longitudinal MRIs using the Whole-Organ Magnetic Resonance Imaging Score in 5 cartilage subregions of each of the medial and lateral tibiofemoral joints. Cartilage loss in a subregion was defined as an increase in the cartilage score of > or = 1 (0-4 scale). The risk for change in the number of subregions with cartilage loss was assessed using Poisson regression, with generalized estimating equations to account for correlations. Analyses were adjusted for age, sex, body mass index, baseline cartilage score, and presence of damaged menisci.

RESULTS

In BOKS, 23 of the 265 included knees (9%) had chondrocalcinosis. In Health ABC, 373 knees were included, of which 69 knees (18.5%) had chondrocalcinosis. In BOKS, knees with chondrocalcinosis had a lower risk of cartilage loss compared with knees without chondrocalcinosis (adjusted risk ratio [RR] 0.4, 95% confidence interval [95% CI] 0.2-0.7) (P = 0.002), and there was no difference in risk in Health ABC (adjusted RR 0.9, 95% CI 0.6-1.5) (P = 0.7). Stratification by intact versus damaged menisci produced similar results within each cohort.

CONCLUSION

In knees with OA, the presence of chondrocalcinosis was not associated with increased cartilage loss. These findings do not support the hypothesis that chondrocalcinosis worsens OA progression.

Trapeziometacarpal subluxation predisposes to incident trapeziometacarpal osteoarthritis (OA): the Framingham Study

OBJECTIVE

Osteoarthritis (OA) of the thumb carpo-metacarpal joint is a common condition that can lead to substantial pain, instability, deformity, and loss of motion. It has been hypothesized that instability of the trapeziometacarpal joint combined with strenuous use can potentially lead to OA. However, as yet there have been no longitudinal evaluations to determine if this hypothesis is true. We examined the relation of radial subluxation to the risk of radiographic OA at trapeziometacarpal joint.

METHODS

We conducted a nested case-control study. We restricted our evaluation of cases to subjects with no radiographic trapeziometacarpal OA at baseline (1967). We defined incident trapeziometacarpal OA as the development of a modified Kellgren and Lawrence grade>or=2 in that joint at a later examination (1992-1993). Radial subluxation of the base of the first metacarpal off the trapezium and the amount of the base of the first metacarpal covering the articulating surface of the trapezium were measured using a digital calculation caliper. We examined the relation of gender-specific quartile groups of radial subluxation to the risk of trapeziometacarpal OA using a conditional logistic regression model.

RESULTS

We assessed 203 men and 431 women. After adjusting for age, handedness, number of other joints with OA, and grip strength, the odds ratios for the risk of trapeziometacarpal OA in men were 1.0, 1.8, 2.7, and 3.1 from the lowest quartile of radial subluxation to the highest quartile, respectively (P for trend=0.015). There was no significant relationship between radial subluxation quartiles and incident trapeziometacarpal OA in women.

CONCLUSION

This study provides evidence that radial subluxation predisposes to subsequent OA of the trapeziometacarpal joint in men.

Osteophytes and progression of knee osteoarthritis

OBJECTIVES

Osteophytes are thought to stabilize an osteoarthritic joint, thereby preventing structural progression. Meagre longitudinal data suggest, however, that they are associated with an increased risk of structural progression. Our objective was to evaluate the effect of osteophyte size on radiographic progression in osteoarthritis (OA).

METHODS

Using data from a natural history study of persons with symptomatic knee OA, we obtained fluoroscopically positioned postero-anterior (PA) radiographs at baseline, 15 and 30 months. Using an atlas, osteophyte size was scored on a scale of 0-3 at each of four sites on the PA film and, for each knee, both compartment-specific (i.e. medial; lateral) and overall osteophyte scores were computed. Progression was defined as an increase over follow-up in medial or lateral joint space narrowing, based on a semiquantitative grading. Mechanical alignment was assessed using long limb films at the 15 month examination. Logistic regression was used to evaluate the relation of osteophyte size with progression, adjusting for age, gender and body mass index, and with and without adjustment for alignment.

RESULTS

Of 270 subjects who had 470 eligible knees with follow-up, 104 (22%) knees showed progression. Overall, osteophyte score modestly increased the risk of progression [odds ratio (OR) per S.D. increase of osteophyte score=1.4 (95% CI 1.1, 1.8, P=0.02)], but this effect weakened and became non-significant after adjustment for limb alignment (OR=1.3). Compartment osteophyte score was strongly associated with malalignment to the side of the osteophyte (e.g. medial osteophyte and varus). Compartment-specific osteophyte score markedly increased the risk of ipsilateral progression (e.g. medial osteophytes --> medial progression) [OR per S.D.=1.9 (95% CI 1.5, 2.5, P<0.001)] and decreased the risk of contralateral progression [OR per S.D.= 0.6 (95% CI 0.5, 0.8, P=0.002)], but these associations diminished when we adjusted for limb alignment (OR=1.5 and 0.7 respectively).

CONCLUSIONS

Large osteophytes do not affect the risk of structural progression. They are strongly associated with malalignment to the side of the osteophyte, and any relation they have with progression is partly explained by the association of malalignment with progression.

Quantitative structure-property relationships on direct photolysis of PCDD/Fs on surfaces of fly ash

Fly ash samples containing polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were generated by combustion of polyvinyl chloride, wood, high-density polyethylene and styrene. By partial least-squares (PLS) regression, quantitative structure-property relationship (QSPR) models were developed for photolysis half-lives (t(1/2)) of PCDD/Fs adsorbed on fly ash surfaces and irradiated by UV-B of simulated sunlight. Quantum chemical descriptors computed by PM3 hamiltonian were used as predictor variables. The cross validated value for the optimal QSPR model was 0.678, indicating robustness and good predictive abilities of the model. The QSPR results showed that the stability of the PCDD/F molecules increased with the increase of chlorine atoms in the parent molecules. Increasing the energy of the highest occupied molecular orbital (E(HOMO)), the energy of the lowest unoccupied molecular orbital (E(LUMO)), E(LUMO)+E(HOMO) and E(LUMO)-E(HOMO) values of the PCDD/Fs led to decrease of log t(1/2) values. Increasing the most negative atomic charge on the oxygen atom of PCDD/Fs led to elevated log t(1/2) values. The log t(1/2) values of PCDD/Fs increased with the decrease of the largest negative atomic charge on a carbon atom.

Molecular structural characteristics governing biocatalytic chlorination of PAHs by chloroperoxidase from Caldariomyces fumago

Based on some fundamental quantum chemical descriptors computed by PM3 Hamiltonian, a quantitative structure-property relationship (QSPR) for specific activity of 17 polycyclic aromatic hydrocarbons (PAHs) of biocatalytic chlorination by chloroperoxidase (CPO) from Caldariomyces fumago was developed using partial least squares (PLS) regression. The model can be used to estimate biocatalytic chlorination reaction rates of PAHs. The main factors affecting specific activity of PAHs of biocatalytic chlorination by CPO from Caldariomyces fumago are absolute hardness, dipole moment, absolute electronegativity, and molecular bulkness of the PAH molecules. The biocatalytic chlorination reaction rates of PAHs with large values of absolute hardness, absolute electronegativity, and molecular bulkness tend to be slow. Increasing dipole moment of PAHs leads to increase the specific activity.

Symmetry and clustering of symptomatic hand osteoarthritis in elderly men and women: the Framingham Study

OBJECTIVE

While symmetry and clustering of radiographic hand osteoarthritis (OA) have been described in middle-aged women, these have not been studied in elderly individuals and similar investigations are lacking for symptomatic hand OA. The goal of this study was to study patterns of joint involvement in symptomatic hand OA among elderly Caucasian men and women.

METHODS

Using data from the Framingham Osteoarthritis Study, we defined a joint as having symptomatic OA if it had symptoms and radiographic OA (Kellgren and Lawrence grade > or =2). We assessed clustering of symptomatic OA using a chi(2)-test and evaluated the interrelationship of occurrence of symptomatic OA among different joints with generalized estimating equations.

RESULTS

Of 976 subjects (age 71-99 yr, 36% men) examined, symptomatic OA more often affected multiple hand joints in an individual than would be expected by chance (P<0.001). The presence of symptomatic OA at a particular joint was strongly associated with symptomatic OA in the same joint of the opposite hand, followed by other joints in the same row of the same hand, and then other joints in the same ray of the same hand. The symmetrical pattern of symptomatic OA was more apparent in women than in men.

CONCLUSION

Our study demonstrates that symptomatic OA often affects multiple hand joints, and is more likely to cluster by row than by ray. The disease also occurs in a remarkably symmetrical pattern, especially in women.

Integrin alpha(v)beta6-associated ERK2 mediates MMP-9 secretion in colon cancer cells

There is general consensus that matrix metalloproteinases are involved in tumour progression. We show herein that inhibition of integrin alpha(v)beta6 expression in colon cancer cells suppresses MMP-9 secretion. This integrin-mediated event is dependent upon direct binding between the beta6 integrin subunit and extracellular signal-regulated kinase 2. Targetting either beta6 or its interaction with extracellular signal-regulated kinase in order to inhibit matrix metalloproteinase activity may offer a useful therapeutic approach in preventing growth and spread of colon cancer.

The effects of antisense insulin-like growth factor-I receptor oligonucleotide on human cord blood lymphocytes

Our objective was to study the effects of type I insulin-like growth factor receptor (IGF-IR) on human cord blood lymphocyte (CBL) functions. First, we used RT-PCR to determine the expression of IGF-IR at the mRNA level in CBL. We then inhibited the expression of IGF-IR in CBL by the antisense oligonucleotide for the IGF-IR gene. We measured the changes in interleukin (IL)-2, -4 and interferon-gamma (IFN gamma) at mRNA levels by RT-PCR, immunoglobulin M (IgM) production by CBL with an ELISA and lymphocyte proliferation by a (3)H-thymidine uptake technique. Our results showed that IGF-IR mRNA was detected in both non-activated and activated CBL, but the expression levels in the activated CBL were higher than those in the non-activated CBL. After being exposed to the antisense oligonucleotide, a 50% reduction in the amount of IGF-IR mRNA occurred. Accordingly, the proliferation of CBL to mitogen was significantly reduced about 50%, and the production of IgM from CBL was also markedly decreased. In the phytohemagglutinin-stimulated CBL culture system, when the IGF-IR antisense oligonucleotide existed, the mRNA levels of IFN gamma and IL-2 decreased 30-50% and IL-4 decreased 20-30%. We concluded that IGF-IR is most likely involved in the process of CBL proliferation and production of immunoglobulin and cytokines. It might therefore play an important role in the modulation of the immune functions.