RESUMO
Objective: To observe the effectiveness and safety of the Colles fracture treated with the integrated retainer pad splint and to compare the clinical and radiological outcomes of the integrated retainer pad splint and the traditional bamboo curtain splint in the treatment of the Colles fracture. Methods: A total of 100 patients with Colles fractures were randomly divided into two groups: the treatment group was fixed with the integrated retainer pad splint (IS), and the control group was fixed with the traditional bamboo curtain splint (TS).The range of wrist motion was measured at follow-up examinations, and volar inclination, ulnar deviation, and radial height were measured on radiographs. Regular follow-up wrist imaging examinations and functional examinations were performed before reduction, after reduction, and at the 1st, 3rd, 5th, and 8th weeks. The two groups were compared in terms of convenience, fracture healing time, X-ray data of volar inclination, ulnar deviation, radial height, and wrist joint function. The relevant data were analyzed with SPSS 25.0 statistical software. Results: There were no notable differences in gender, age, and injured side between IS and TS groups. In terms of operation time, IS was better than the TS group (P < 0.05), and the operation time in the IS group was shorter. On the basis of X-ray data of volar inclination, ulnar deviation, and radial height measured on radiographs, the difference between the IS and TS groups was statistically significant (P < 0.05), which showed that the IS group was more stable in fracture fixation and had less reduction loss during the treatment process. At the 8th week of treatment, the wrist Gartland-Werley score of the two groups showed that the two fixation methods are equivalent in restoring wrist joint function (P > 0.05); however, in terms of the excellent and good rate of wrist joint function, the IS group scored 96% was higher than the TS group (80%). Conclusion: Compared with the traditional bamboo curtain splint, the integrated retainer pad splint is more convenient and stable, and it has less reduction loss during the treatment. Repair of the Colles fracture using the integrated retainer pad splint with external fixation results in nearly normal return of function, which is significantly better than using the traditional bamboo curtain splint.
RESUMO
The human calcium-sensing receptor (CaSR) is a class C G protein-coupled receptor (GPCR) responsible for maintaining Ca2+ homeostasis in the blood. The general consensus is that extracellular Ca2+ is the principal agonist of CaSR. Aliphatic and aromatic L-amino acids, such as L-Phe and L-Trp, increase the sensitivity of CaSR towards Ca2+ and are considered allosteric activators. Crystal structures of the extracellular domain (ECD) of CaSR dimer have demonstrated Ca2+ and L-Trp binding sites and conformational changes of the ECD upon Ca2+/L-Trp binding. However, it remains to be understood at the structural level how Ca2+/L-Trp binding to the ECD leads to conformational changes in transmembrane domains (TMDs) and consequent CaSR activation. Here, we determined the structures of full-length human CaSR in the inactive state, Ca2+- or L-Trp-bound states, and Ca2+/L-Trp-bound active state using single-particle cryo-electron microscopy. Structural studies demonstrate that L-Trp binding induces the closure of the Venus flytrap (VFT) domain of CaSR, bringing the receptor into an intermediate active state. Ca2+ binding relays the conformational changes from the VFT domains to the TMDs, consequently inducing close contact between the two TMDs of dimeric CaSR, activating the receptor. Importantly, our structural and functional studies reveal that Ca2+ ions and L-Trp activate CaSR cooperatively. Amino acids are not able to activate CaSR alone, but can promote the receptor activation in the presence of Ca2+. Our data provide complementary insights into the activation of class C GPCRs and may aid in the development of novel drugs targeting CaSR.