Discovery of (R)-2-amino-3-triazolpropanoic acid derivatives as NMDA receptor glycine site agonists with GluN2 subunit-specific activity

N-Methyl-d-aspartate (NMDA) receptors play critical roles in central nervous system function and are involved in variety of brain disorders. We previously developed a series of (R)-3-(5-furanyl)carboxamido-2-aminopropanoic acid glycine site agonists with pronounced variation in activity among NMDA receptor GluN1/2A-D subtypes. Here, a series of (R)-2-amino-3-triazolpropanoic acid analogues with a novel chemical scaffold is designed and their pharmacological properties are evaluated at NMDA receptor subtypes. We found that the triazole can function as a bioisostere for amide to produce glycine site agonists with variation in activity among NMDA receptor subtypes. Compounds 13g and 13i are full and partial agonists, respectively, at GluN1/2C and GluN1/2D with 3- to 7-fold preference in agonist potency for GluN1/2C-D over GluN1/2A-B subtypes. The agonist binding mode of these triazole analogues and the mechanisms by which the triazole ring can serve as a bioisostere for amide were further explored using molecular dynamics simulations. Thus, the novel (R)-2-amino-3-triazolpropanoic acid derivatives reveal insights to agonist binding at the GluN1 subunit of NMDA receptors and provide new opportunities for the design of glycine site agonists.

Do elderly patients gain as much benefit from arthroscopic rotator cuff repair as their younger peers?

BACKGROUND

This study was conducted to ascertain whether patients aged older than 75 years achieve outcomes after arthroscopic rotator cuff repair comparable to younger patients.

METHODS

Arthroscopic cuff repair was performed in 60 shoulders of 59 patients aged older than 75 years. A control group of 60 younger patients, matched for sex, tear size, and American Society of Anesthesiology Functional Classification grade were included. Surgery occurred from 2006 to 2016. Prospective outcomes were the Constant score (CS), Subjective Shoulder Value, pain, satisfaction, and operative complications. Mean follow-up was 29 months.

RESULTS

The elderly group was a mean age of 78 years compared with 59 years for controls. Tear sizes were 25 massive, 20 large, 12 medium, and 3 small. The CS improved by 25.1 points in elderly patients compared with 23.7 points for controls (P = .742). Pain improved by 7.5 of 15 in elderly patients vs. 6.2 of 15 in controls (P = .055). Fifty-five of 59 older patients were satisfied compared with 52 of 60 controls (P = .378). The overall complication rate did not differ between the groups (P = .509). Both groups had 1 infection and 1 stiffness. An acromioclavicular joint cyst developed in 1 younger patient, and a traumatic retear occurred in 1 patient. Subsequent reverse total shoulder arthroplasty was performed in 4 elderly patients at a mean of 28 months after cuff repair. Massive tears had higher risk for subsequent reverse total shoulder arthroplasty (P = .026).

CONCLUSION

Elderly patients benefit as much from arthroscopic rotator cuff repair as their younger counterparts. Similar improvements in CS, Subjective Shoulder Value, pain, and satisfaction occurred for both elderly and control patients. Arthroscopic repair was safe and effective in both groups. Even elderly patients with massive tears showed clinically significant improvements. Arthroscopic rotator cuff repair should be considered as a valuable treatment irrespective of age.