De Quervain tendinitis after total trapeziometacarpal joint arthroplasty: Biomechanical evaluation of tendon excursion in the first extensor tendon compartment

De Quervain's tenosynovitis is the most common complication after total trapeziometacarpal joint replacement. Etiology is unclear. Implantation of a ball-in-socket implant changes the biomechanics of the normal trapeziometacarpal saddle joint and increases its range of motion. The present study demonstrates that this procedure also significantly increases excursion of the abductor pollicis longus and extensor pollicis brevis tendons during thumb flexion-extension, and not during thumb abduction-adduction. Increased tendon gliding under the retinaculum of the first extensor tendon compartment could predispose to the development frictional tenosynovitis and play a role in the development of de Quervain's syndrome after total trapeziometacarpal joint replacement. LEVEL OF EVIDENCE: Not applicable (laboratory study).

The meiosis-specific Cdc20 family-member Ama1 promotes binding of the Ssp2 activator to the Smk1 MAP kinase

Smk1 is a meiosis-specific MAP kinase that is activated by a binding partner, Ssp2. This study shows that the meiosis-specific Cdc20 homologue, Ama1, triggers Ssp2/Smk1 complex formation at specialized meiotic membranes as nuclear segregation is being completed, thus triggering kinase activity at a specific place and time during this developmental program.

Smk1 is a meiosis-specific MAP kinase (MAPK) in budding yeast that is required for spore formation. It is localized to prospore membranes (PSMs), the structures that engulf haploid cells during meiosis II (MII). Similar to canonically activated MAPKs, Smk1 is controlled by phosphorylation of its activation-loop threonine (T) and tyrosine (Y). However, activation loop phosphorylation occurs via a noncanonical two-step mechanism in which 1) the cyclin-dependent kinase activating kinase Cak1 phosphorylaytes T207 during MI, and 2) Smk1 autophosphorylates Y209 as MII draws to a close. Autophosphorylation of Y209 and catalytic activity for substrates require Ssp2, a meiosis-specific protein that is translationally repressed until anaphase of MII. Ama1 is a meiosis-specific targeting subunit of the anaphase-promoting complex/cyclosome that regulates multiple steps in meiotic development, including exit from MII. Here, we show that Ama1 activates autophosphorylation of Smk1 on Y209 by promoting formation of the Ssp2/Smk1 complex at PSMs. These findings link meiotic exit to Smk1 activation and spore wall assembly.

Is small beautiful if it isn't viable? The case of nursing homes

The optimal size of nursing home is examined in the light of overseas and Australian research evidence. The economic optimal size nursing home was found to be in the range of 45-55 beds for a sample of proprietary New South Wales homes in 1978-9 where average weekly expenditure per bed was minimised. However, this did not take into account a number of other important social and environmental factors as well as costs of travel and the quality of care provided or the characteristics of patients. When these factors are considered, evidence suggests that larger than average homes have the economic advantage. Smaller adapted residences, or those incorporating group living design, may be more homelike for residents but at slightly higher cost. Thus there is unlikely to be one single optimal size of home but rather a range. The final selection of scale is therefore a matter of striking a compromise between these and other factors in each situation.