Repair of the dorsal capsuloligamentous scapholunate septum during arthroscopic resection of painful dorsal wrist ganglion cyst: Comparative analysis of two techniques.

We compared arthroscopic cyst resection (ACR) of dorsal ganglia of the wrist, either associated to reconstruction of the dorsal capsuloligamentous scapholunate septum (ACR-DCSS) in 66 cases in which the ganglia were painful on exertion, or isolated ACR in 15 pain-free cases. A single-center retrospective study analyzed data for the period April 2013 to May 2021. The main aim was to compare pre- and post-operative functional results (pain at rest (on a numerical rating scale: NRS), pain under effort (NRS), range of motion (°), grip strength (kg)) and recurrence rate between the two techniques. The study hypothesis was that DCSS repair improves recurrence of dorsal ganglion cyst and functional outcome. The ACR-DCSS group showed significant improvement in extension, pronation, supination, radial inclination, ulnar inclination, grip strength, pain at rest and pain on exertion. The ACR group showed significant improvement in pronation, ulnar inclination and pain on exertion. There was a significant difference in recurrence rate, in favor of ACR-DCSS. Recovery was also significantly better for the ACR-DCSS group in terms of extension, supination and pain at rest. Arthroscopic treatment of wrist ganglion cyst is a reliable, minimally invasive and reproducible technique that produces good results in terms of pain and recovery of range of motion, with significantly lower recurrence rate in case of DCSS repair. Level of evidence: Therapeutic III.

Expression cloning of KCRF, a potassium channel regulatory factor.

By functional coexpression screening of a rat cDNA library in Xenopus oocytes, we have cloned a protein (KCRF: K Channel Regulatory Factor) that reduces currents of several K(+) channels: G protein-activated GIRK1/4 (K(ir)3.1/K(ir)3.4), inward rectifier IRK1 (K(ir)2.1), and voltage-dependent K(V)1.1/K(V)beta1.1. KCRF did not modulate two other K(+) channels: ROMK1 (K(ir)1.1) and GIRK1/2 (K(ir)3.1/K(ir)3.2) and the voltage-dependent L-type Ca(2+) channels. Western blot analysis showed that KCRF is ubiquitous in rat tissues. Biochemical and electrophysiological experiments revealed that coexpression of KCRF causes a decrease in the level of expression of IRK1 and K(V)1.1/K(V)beta1.1 proteins in the oocytes.

Tyrosine 140 of the gamma-aminobutyric acid transporter GAT-1 plays a critical role in neurotransmitter recognition.

The gamma-aminobutyric acid (GABA) transporter GAT-1 is located in nerve terminals and catalyzes the electrogenic reuptake of the neurotransmitter with two sodium ions and one chloride. We now identify a single tyrosine residue that is critical for GABA recognition and transport. It is completely conserved throughout the superfamily, and even substitution to the other aromatic amino acids, phenylalanine (Y140F) and tryptophan (Y140W), results in completely inactive transporters. Electrophysiological characterization reveals that both mutant transporters exhibit the sodium-dependent transient currents associated with sodium binding as well as the chloride-dependent lithium leak currents characteristic of GAT-1. On the other hand, in both mutants GABA is neither able to induce a steady-state transport current nor to block their transient currents. The nontransportable analog SKF 100330A potently inhibits the sodium-dependent transient in the wild type GAT-1 but not in the Y140W transporter. It partly blocks the transient of Y140F. Thus, although sodium and chloride binding are unimpaired in the tyrosine mutants, they have a specific defect in the binding of GABA. The total conservation of the residue throughout the family suggests that tyrosine 140 may be involved in the liganding of the amino group, the moiety common to all of the neurotransmitters.