A Genetically Encoded Photocaged Cysteine for Facile Site-Specific Introduction of Conjugation-Ready Thiol Residues in Antibodies.

Antibody-drug conjugates (ADCs) have emerged as a powerful class of anticancer therapeutics that enable the selective delivery of toxic payloads into target cells. There is increasing appreciation for the importance of synthesizing such ADCs in a defined manner where the payload is attached at specific permissive sites on the antibody with a defined drug to antibody ratio. Additionally, the ability to systematically alter the site of attachment is important to fine-tune the therapeutic properties of the ADC. Engineered cysteine residues have been used to achieve such site-specific programmable attachment of drug molecules onto antibodies. However, engineered cysteine residues on antibodies often get "disulfide-capped" during secretion and require reductive regeneration prior to conjugation. This reductive step also reduces structurally important disulfide bonds in the antibody itself, which must be regenerated through oxidation. This multistep, cumbersome process reduces the efficiency of conjugation and presents logistical challenges. Additionally, certain engineered cysteine sites are resistant to reductive regeneration, limiting their utility and the overall scope of this conjugation strategy. In this work, we utilize a genetically encoded photocaged cysteine residue that can be site-specifically installed into the antibody. This photocaged amino acid can be efficiently decaged using light, revealing a free cysteine residue available for conjugation without disrupting the antibody structure. We show that this ncAA can be incorporated at several positions within full-length recombinant trastuzumab and decaged efficiently. We further used this method to generate a functional ADC site-specifically modified with monomethyl auristatin F (MMAF).

Spinal column and spinal cord injuries in mountain bikers: a 13-year review.

BACKGROUND: Multiple studies have described in general the injuries associated with mountain biking, and detailed accounts of spine injuries sustained in hockey, gymnastics, skiing, snowboarding, rugby, and paragliding have previously been published. However, no large-scale detailed assessment of mountain biking associated spinal fractures and spinal cord injuries has previously been published. PURPOSE: This study was undertaken to describe the patient demographics, injuries, mechanisms, treatments, outcomes, and resource requirements associated with spine injuries sustained while mountain biking. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Patients who were injured while mountain biking, and who were seen at a provincial spine referral center between 1995 and 2007 inclusive, with spinal cord injuries and/or spine fracture were included. A chart review was performed to obtain demographic data, and details of the injury, treatment, outcome, and resource requirements. RESULTS: A total of 102 men and 5 women were identified for inclusion. The mean age at injury was 32.7 years (95% confidence interval 30.6, 35.0). Seventy-nine patients (73.8%) sustained cervical injuries, while the remainder sustained thoracic or lumbar injuries. Forty-three patients (40.2%) sustained a spinal cord injury. Of those with cord injuries, 18 (41.9%) were American Spinal Injury Association (ASIA) A, 5 (11.6%) were ASIA B, 10 (23.3%) ASIA C, and 10 (23.3%) ASIA D. Sixty-seven patients (62.6%) required surgical treatment. The mean length of stay in an acute hospital bed was 16.9 days (95% confidence interval 13.1, 30.0). Thirty-three patients (30.8%) required intensive care unit attention, and 31 patients (29.0%) required inpatient rehabilitation. Of the 43 patients (40.2%) seen with spinal cord injuries, 14 (32.5%) improved by 1 ASIA category, and 1 (2.3%) improved by 2 ASIA categories. Two patients remained ventilator-dependent at discharge. CONCLUSION: Spine fractures and spinal cord injuries caused by mountain biking accidents typically affect young, male, recreational riders. The medical, personal, and societal costs of these injuries are high. Injury prevention should remain a primary goal, and further research is necessary to explore the utility of educational programs, and the effect of helmets and other protective gear on spine injuries sustained while mountain biking.

Spinal epidural abscess: a 5-year case-controlled review of neurologic outcomes after rehabilitation.

OBJECTIVE: To describe the neurologic outcomes of 29 spinal epidural abscess (SEA) patients after rehabilitation compared with a case-controlled traumatic spinal cord injury (TSCI) cohort. DESIGN: Five-year retrospective chart review. SETTING: University-affiliated surgical spine unit and inpatient rehabilitation program. PARTICIPANTS: Patients (n=29; 19 men, 10 women) requiring inpatient rehabilitation after SEA and TSCI case controls (n=29) matched by level of injury, American Spinal Injury Association (ASIA) Impairment Scale (AIS), ASIA motor score (AMS), sex, and age. MAIN OUTCOME MEASURE: The primary outcome was a change in AMS from acute admission to discharge from inpatient rehabilitation. RESULTS: Despite having lower admission motor scores, there was a significant trend toward greater neurologic recovery in the SEA group (P=.047). In contrast to what is known regarding recovery from complete TSCI, this study shows potential for dramatic recovery in SEA subjects presenting with AIS grade A deficit with a 73% conversion rate to incomplete status; out of 11 SEA subjects with initial AIS grade A, 2 improved to AIS grade B, 1 to AIS grade C, and 5 to AIS grade D. CONCLUSIONS: This study shows the potential for a significant improvement in neurologic deficits related to SEA. Based on the results of our study, it is clearly inappropriate to generalize recovery patterns seen in the TSCI patient population to SEA-associated myelopathy because the latter appears to have more favorable outcomes.