Radiographic Assessment of the Robert and Lateral Views in Trapeziometacarpal Osteoarthrosis.

BACKGROUND: To evaluate the effectiveness of the Robert view in assessing trapeziometacarpal arthrosis and to compare the accuracy of the Robert and lateral views in staging trapeziometacarpal (TM) joint arthrosis. METHODS: Patient demographics were obtained. Four participating raters reviewed 62 randomly selected thumb x-rays of patients presenting with thumb TM joint pain. Lateral and Robert-hyperpronation views were assessed using an analysis of 13 criteria. RESULTS: X-rays of 62 thumbs for 58 patients were evaluated. The average patients' age was 64 (47-87) and 51 (80%) were females. The majority of X-rays evaluated fell into stage 3. Stage 2 was the second most common level of arthritis encountered and the least was stage 1. More osteophytes were encountered in the trapezium than metacarpal on both the Robert and lateral views. The Robert view was superior in detecting osteophytes on the trapezium than the lateral view. Osteophyte size varied from 1.7 to 2 mm. The lateral view displayed 61 cases with dorsal metacarpal subluxation (98%). The Robert view displayed 48 cases (77%) with radial metacarpal subluxation and 9 cases (15%) with ulnar metacarpal subluxation. Thumb metacarpal adduction deformity was encountered on the lateral view in 20 cases (32%) whereas on the Robert view it was encountered in 14 cases (23%). Subchondral sclerosis was encountered on the Robert view in 56 thumbs (90%) while it was seen on the lateral view in 52 thumbs (84%). Pantrapezial arthritis involving the STT joint was encountered equally in 16 cases (26%) on the Robert view and the lateral views. The study found a moderate level of interrater reliability on both the lateral and Robert views. With the exception of osteophytes encountered on the trapezium versus the metacarpal, there were no other statistically significant findings. CONCLUSIONS: This study confirms that each of the Robert and lateral views offer unique information and combining both views enhances the ability to assess radiographic disease severity, and should be the recommended set of X-rays for assessing TM osteoarthrosis.

Analysis of metal ion dependence in glmS ribozyme self-cleavage and coenzyme binding.

The bacterial glmS ribozyme is mechanistically unique among both riboswitches and RNA catalysts. Its self-cleavage activity is the basis of riboswitch regulation of glucosamine-6-phosphate (GlcN6P) production, and catalysis requires GlcN6P as a coenzyme. Previous work has shown that the coenzyme amine of GlcN6P is essential for glmS ribozyme self-cleavage, as is its protonation state. Metal ions are also essential within the glmS ribozyme core for both structure and function of the ribozyme. Although metal ions do not directly promote catalysis, we show that metal ion identity and the varying physicochemical properties of metal ions have an impact on the rate of glmS ribozyme self-cleavage. Specifically, these studies demonstrate that metal ion identity influences the overall apparent pK(a) of ribozyme self-cleavage, and metal ion binding largely reflects phosphate oxygen affinity. Results suggest that metal ions take alternative roles in supporting the mechanism of catalysis.

Primary squamous cell carcinoma of lung in a 13-year-old boy: a case report.

We are reporting a very rare case of primary bronchogenic squamous cell carcinoma (SCC) with bone metastasis in a 13-year-old boy. A brief review of the English literature on this rare neoplasm in childhood is presented.

Backbone and nucleobase contacts to glucosamine-6-phosphate in the glmS ribozyme.

The glmS ribozyme resides in the 5' untranslated region of glmS mRNA and functions as a catalytic riboswitch that regulates amino sugar metabolism in certain Gram-positive bacteria. The ribozyme catalyzes self-cleavage of the mRNA and ultimately inhibits gene expression in response to binding of glucosamine-6-phosphate (GlcN6P), the metabolic product of the GlmS protein. We have used nucleotide analog interference mapping (NAIM) and suppression (NAIS) to investigate backbone and nucleobase functional groups essential for ligand-dependent ribozyme function. NAIM using GlcN6P as ligand identified requisite structural features and potential sites of ligand and/or metal ion interaction, whereas NAIS using glucosamine as ligand analog revealed those sites that orchestrate recognition of ligand phosphate. These studies demonstrate that the ligand-binding site lies in close proximity to the cleavage site in an emerging model of ribozyme structure that supports a role for ligand within the catalytic core.

Ligand requirements for glmS ribozyme self-cleavage.

Natural RNA catalysts (ribozymes) perform essential reactions in biological RNA processing and protein synthesis, whereby catalysis is intrinsic to RNA structure alone or in combination with metal ion cofactors. The recently discovered glmS ribozyme is unique in that it functions as a glucosamine-6-phosphate (GlcN6P)-dependent catalyst believed to enable "riboswitch" regulation of amino-sugar biosynthesis in certain prokaryotes. However, it is unclear whether GlcN6P functions as an effector or coenzyme to promote ribozyme self-cleavage. Herein, we demonstrate that ligand is absolutely requisite for glmS ribozyme self-cleavage activity. Furthermore, catalysis both requires and is dependent upon the acid dissociation constant (pKa) of the amine functionality of GlcN6P and related compounds. The data demonstrate that ligand is integral to catalysis, consistent with a coenzyme role for GlcN6P and illustrating an expanded capacity for biological RNA catalysis.