Biomechanical factors and physical examination findings in osteoarthritis of the knee: associations with tissue abnormalities assessed by conventional radiography and high-resolution 3.0 Tesla magnetic resonance imaging

Introduction

We aimed to explore the associations between knee osteoarthritis (OA)-related tissue abnormalities assessed by conventional radiography (CR) and by high-resolution 3.0 Tesla magnetic resonance imaging (MRI), as well as biomechanical factors and findings from physical examination in patients with knee OA.

Methods

This was an explorative cross-sectional study of 105 patients with knee OA. Index knees were imaged using CR and MRI. Multiple features from CR and MRI (cartilage, osteophytes, bone marrow lesions, effusion and synovitis) were related to biomechanical factors (quadriceps and hamstrings muscle strength, proprioceptive accuracy and varus-valgus laxity) and physical examination findings (bony tenderness, crepitus, bony enlargement and palpable warmth), using multivariable regression analyses.

Results

Quadriceps weakness was associated with cartilage integrity, effusion, synovitis (all detected by MRI) and CR-detected joint space narrowing. Knee joint laxity was associated with MRI-detected cartilage integrity, CR-detected joint space narrowing and osteophyte formation. Multiple tissue abnormalities including cartilage integrity, osteophytes and effusion, but only those detected by MRI, were found to be associated with physical examination findings such as crepitus.

Conclusion

We observed clinically relevant findings, including a significant association between quadriceps weakness and both effusion and synovitis, detected by MRI. Inflammation was detected in over one-third of the participants, emphasizing the inflammatory component of OA and a possible important role for anti-inflammatory therapies in knee OA. In general, OA-related tissue abnormalities of the knee, even those detected by MRI, were found to be discordant with biomechanical and physical examination features.     

Persistence with anti-tumour necrosis factor therapies in patients with psoriatic arthritis: observational study from the British Society of Rheumatology Biologics Register

Introduction  

Anti-TNF therapies represent a breakthrough in the treatment of severe psoriatic arthritis. However, little is known about long-term drug persistence with these treatments in patients with psoriatic arthritis in routine clinical practice. The aim of this study was to assess persistence with first-course and second-course treatment with anti-TNF agents in a prospective cohort of psoriatic arthritis patients and to identify factors associated with and reasons for drug discontinuation.     

Forefoot disease activity in rheumatoid arthritis patients in remission: results of a cohort study

Introduction  

The aim of our study was to investigate the presence of disease activity in the metatarsophalangeal (MTP) joints of the forefoot in rheumatoid arthritis (RA) patients in remission according to the Disease Activity Score based on 28 joints (DAS28) remission criterion.     

Microbial diversity and complexity in hypersaline environments: A preliminary assessment

The microbial communities in solar salterns and a soda lake have been characterized using two techniques: BIOLOG, to estimate the metabolic potential, and amplicon length heterogeneity analysis, to estimate the molecular diversity of these communities. Both techniques demonstrated that the halophilic Bacteria and halophilic Archaea populations in the Eilat, Israel saltern are dynamic communities with extensive metabolic potentials and changing community structures. Halophilic Bacteria were detected in Mono Lake and the lower salinity ponds at the Shark Bay saltern in Western Australia, except when the crystallizer samples were stressed by exposure to Acid Green Dye #9899. At Shark Bay, halophilic Archaea were found only in the crystallizer samples. These data confirm both the metabolic diversity and the phylogenetic complexity of the microbial communities and assert the need to develop more versatile media for the cultivation of the diversity of bacteria in hypersaline environments. Journal of Industrial Microbiology & Biotechnology (2002) 28, 48–55 DOI: 10.1038/sj/jim/7000175 Received 20 May 2001/ Accepted in revised form 15 June 2001     

Wildlife detector dogs and camera traps: a comparison of techniques for detecting feral cats

A major challenge in controlling overabundant wildlife is monitoring their populations, particularly as they decline to very low density. Camera traps and wildlife detector dogs are increasingly being used for this purpose. We compared the cost-effectiveness of these two approaches for detecting feral cats (Felis catus) on two pastoral properties in Hawke's Bay, North Island, New Zealand. One property was subject to intensive pest removal, while the other had no recent history of pest control. Camera traps and wildlife detector dogs detected cats at similar rates at both sites. The operating costs of each method were also comparable. We identify a number of advantages and disadvantages of each technique, and suggest priorities for further research.     

Role of mismatch repair in the Escherichia coli UVM response.

Mutagenesis at 3,N4-ethenocytosine (epsilonC), a nonpairing mutagenic lesion, is significantly enhanced in Escherichia coli cells pretreated with UV, alkylating agents, or H2O2. This effect, termed UVM (for UV modulation of mutagenesis), is distinct from known DNA damage-inducible responses, such as the SOS response, the adaptive response to alkylating agents, or the oxyR-mediated response to oxidative agents. Here, we have addressed the hypothesis that UVM results from transient depletion of a mismatch repair activity that normally acts to reduce mutagenesis. To test whether the loss of mismatch repair activities results in the predicted constitutive UVM phenotype, E. coli cells defective for methyl-directed mismatch repair, for very-short-patch repair, or for the N-glycosylase activities MutY and MutM were treated with the UVM-inducing agent 1-methyl-3-nitro-1-nitrosoguanidine, with subsequent transfection of M13 viral single-stranded DNA bearing a site-specific epsilonC lesion. Survival of the M13 DNA was measured as transfection efficiency, and mutation fixation at the lesion was characterized by multiplex sequencing technology. The results showed normal UVM induction patterns in all the repair-defective strains tested. In addition, normal UVM induction was observed in cells overexpressing MutH, MutL, or MutS. All strains displayed UVM reactivation, the term used to describe the increased survival of epsilonC-containing DNA in UVM-induced cells. Taken together, these results indicate that the UVM response is independent of known mismatch repair systems in E. coli and may thus represent a previously unrecognized misrepair or misreplication pathway.     

A Staphylococcus aureus regulatory system that responds to host heme and modulates virulence

Staphylococcus aureus, a bacterium responsible for tremendous morbidity and mortality, exists as a harmless commensal in approximately 25% of humans. Identifying the molecular machinery activated upon infection is central to understanding staphylococcal pathogenesis. We describe the heme sensor system (HssRS) that responds to heme exposure and activates expression of the heme-regulated transporter (HrtAB). Inactivation of the Hss or Hrt systems leads to increased virulence in a vertebrate infection model, a phenotype that is associated with an inhibited innate immune response. We suggest that the coordinated activity of Hss and Hrt allows S. aureus to sense internal host tissues, resulting in tempered virulence to avoid excessive host tissue damage. Further, genomic analyses have identified orthologous Hss and Hrt systems in Bacillus anthracis, Listeria monocytogenes, and Enterococcus faecalis, suggesting a conserved regulatory system by which Gram-positive pathogens sense heme as a molecular marker of internal host tissue and modulate virulence.     

H-Type Bovine Spongiform Encephalopathy: Complex Molecular Features and Similarities with Human Prion Diseases

We previously reported that some cattle affected by bovine spongiform encephalopathy (BSE) showed distinct molecular features of the protease-resistant prion protein (PrP^res) in Western blot, with a 1–2 kDa higher apparent molecular mass of the unglycosylated PrP^res associated with labelling by antibodies against the 86–107 region of the bovine PrP protein (H-type BSE). By Western blot analyses of PrP^res, we now showed that the essential features initially described in cattle were observed with a panel of different antibodies and were maintained after transmission of the disease in C57Bl/6 mice. In addition, antibodies against the C-terminal region of PrP revealed a second, more C-terminally cleaved, form of PrP^res (PrP^res #2), which, in unglycosylated form, migrated as a ≈ 14 kDa fragment. Furthermore, a PrP^res fragment of ≈7 kDa, which was not labelled by C-terminus-specific antibodies and was thus presumed to be a product of cleavage at both N- and C-terminal sides of PrP protein, was also detected. Both PrP^res #2 and ≈7 kDa PrP^res were detected in cattle and in C57Bl/6 infected mice. These complex molecular features are reminiscent of findings reported in human prion diseases. This raises questions regarding the respective origins and pathogenic mechanisms in prion diseases of animals and humans.Key Words: prion, BSE, Creutzfeldt-Jakob, Gerstmann-Sträussler-Scheinker, Western blot, amyloid