Management of chronic knee pain caused by postsurgical or posttraumatic neuroma of the infrapatellar branch of the saphenous nerve.

PURPOSE: Injury to the infrapatellar branch of the saphenous nerve (IBSN) is a relatively common complication after knee surgery, which can interfere with patient satisfaction and functional outcome. In some cases, injury to the IBSN can lead to formation of a painful neuroma. The purpose of this study was to report the results of surgical treatment in a series of patients with IBSN painful neuroma. METHODS: We retrospectively identified 37 patients who underwent resection of IBSN painful neuroma at our institution, after failure of non-operative treatment for a minimum of 6 months. Injury to the IBSN resulted from prior orthopedic surgery, vascular surgery, tumor resection, trauma, or infection. Leg pain and health-related quality of life were measured using the numeric rating scale (NRS) and EuroQol 5 dimensions (EQ-5D) questionnaire, respectively. Clinically meaningful improvement in leg pain was defined as reduction in NRS by at least 3 points. Predictors of favorable and unfavorable surgical outcome were investigated using multivariable logistic regression analysis. RESULTS: Patient-reported leg pain, health-related quality of life, and overall satisfaction with the surgical outcome were obtained at 94 ± 52.9 months after neuroma surgery. Postoperative patient-reported outcomes were available for 25 patients (68% of the cohort), of whom 20 patients (80.0%) reported improvement in leg pain, 17 patients (68.0%) reported clinically meaningful improvement in leg pain, and 17 patients (68%) reported improvement in health-related quality of life. The average NRS pain score improved from 9.43 ± 1.34 to 5.12 ± 3.33 (p < 0.01) and the average EQ-5D functional score improved from 10.48 ± 2.33 to 7.84 ± 2.19 (p < 0.01). Overall patient reported satisfaction with the surgical outcome was good to excellent for 18 patients (72.0%). Older age, multiple prior orthopedic knee surgeries, and failed prior attempts to resect an IBSN neuroma were associated with non-favorable surgical outcome. CONCLUSION: We conclude that surgical intervention is efficacious for appropriately selected patients suffering from IBSN painful neuroma.

Early postoperative dressing removal in hand surgery: Novel concepts for individualized surgical dressing management.

Postoperative dressing protocols after clean surgery without implant vary widely. The purpose of this study was to elucidate whether early postoperative dressing removal is a valid option, as compared to untouched dressing or twice-weekly dressing change approach. A prospective randomized study was conducted on patients who underwent carpal tunnel release (CTR) or trigger finger release (TFR) between January and November 2020. Patients were randomly distributed into 3 groups: surgical dressing untouched until first follow up (SDU); surgical dressing changed twice a week in a health maintenance organization (HMO); and surgical dressing removed at first postoperative day (SDR). Data collected included patient characteristics, pre-and post-operative functional (QuickDASH) and autonomy (Instrumental Activities of Daily Living performance (IADL)) scores, Vancouver scar scale (VSS) and potential complications. Eighty-four patients were included: 28 (33.3%), 29 (34.5%) and 27 (32.1%) in the SDU, HMO and SDR groups, respectively. Deterioration in mean IADL score at 2-week follow-up was statistically significant in the HMO group (mean delta 3.35, p = 0.008). Quick DASH score improved significantly between preoperative and 2-week follow-up values only in the SDU group (mean delta 9.12, p = 0.012). Other parameters, including wound complications, did not differ significantly between groups. Early removal of postoperative dressing and immediate wound exposure was a safe option after CTR and TFR. An untouched bulky dressing correlated with early functional improvement. Finally, iterative dressing change in HMO showed no benefit and led to significant deterioration in early postoperative autonomy. IRB APPROVAL: 0548-18-TLV. LEVEL OF EVIDENCE: I.

FRET-based cyanine probes for monitoring ligation reactions and their applications to mechanistic studies and catalyst screening.

There is an ever-increasing need to design better methods to selectively connect two molecules under mild aqueous conditions on a small scale. The process of finding such methods significantly relies on the employment of an appropriate assay. We report here a modular FRET-based assay to monitor such reactions and illustrate how the assay is used to monitor two particular reactions: native chemical ligation (NCL) and oxime ligation. For both reactions we show that by employing appropriately designed probes FRET measurements could be used to monitor the reaction's progress. We additionally demonstrate the usefulness of the developed probe system to study the mechanisms of the ligation reactions, for example, in monitoring the formation of a trimeric intermediate in the NCL reaction. Finally, we demonstrate that FRET measurements conducted in our system allow the quantification of the reaction yield and we show the application of our FRET-based assay to catalyst screening for the oxime ligation.

Neuroblastoma directed therapy by a rational prodrug design of etoposide as a substrate for tyrosine hydroxylase.

Tumor directed cytotoxic therapy is one of the major challenges for the success of chemotherapy. In order to accomplish this goal in neuroblastoma, we rationally designed a prodrug of etoposide as substrate for tyrosine hydroxylase, a well established neuroblastoma associated enzyme. Here, we report synthesis and characterization of a 3,4 dihydroxy-phenyl carbamate derivative of etoposide. In order to demonstrate activation by tyrosine hydroxylase, the coding sequence of murine tyrosine hydroxylase was generated by reverse transcriptase-polymerase chain reaction from NXS2 neuroblastoma cells and cloned into the pRSET-A bacterial expression vector. The enzyme was expressed in Escherichia coli, characterized by Western blot and enzymatic activity was demonstrated by conversion of tyrosine into DOPA in the presence of cofactors using reversed phase high-performance liquid chromatography. Under these enzymatic conditions, we demonstrate conversion of 3,4 dihydroxy-phenyl carbamate prodrug into free etoposide. This effect was clearly mediated by the enzyme since bacteria transformed with the empty vector were ineffective of prodrug activation. Furthermore, tyrosine hydroxylase positive cells exposed to the etoposide prodrug were effectively killed in contrast to tyrosine hydroxylase negative controls. These findings demonstrate that etoposide can be designed as a prodrug substrate for tyrosine hydroxylase and thereby establish proof of concept for neuroblastoma directed enzyme prodrug therapy.

In vivo activity in a catalytic antibody-prodrug system: Antibody catalyzed etoposide prodrug activation for selective chemotherapy.

Effective chemotherapy remains a key issue for successful cancer treatment in general and neuroblastoma in particular. Here we report a chemotherapeutic strategy based on catalytic antibody-mediated prodrug activation. To study this approach in an animal model of neuroblastoma, we have synthesized prodrugs of etoposide, a drug widely used to treat this cancer in humans. The prodrug incorporates a trigger portion designed to be released by sequential retro-aldol/retro-Michael reactions catalyzed by aldolase antibody 38C2. This unique prodrug was greater than 10(2)-fold less toxic than etoposide itself in in vitro assays against the NXS2 neuroblastoma cell line. Drug activity was restored after activation by antibody 38C2. Proof of principle for local antibody-catalyzed prodrug activation in vivo was established in a syngeneic model of murine neuroblastoma. Mice with established 100-mm3 s.c. tumors who received one intratumoral injection of antibody 38C2 followed by systemic i.p. injections with the etoposide prodrug showed a 75% reduction in s.c. tumor growth. In contrast, injection of either antibody or prodrug alone had no antitumor effect. Systemic injections of etoposide at the maximum tolerated dose were significantly less effective than the intratumoral antibody 38C2 and systemic etoposide prodrug combination. Significantly, mice treated with the prodrug at 30-fold the maximum tolerated dose of etoposide showed no signs of prodrug toxicity, indicating that the prodrug is not activated by endogenous enzymes. These results suggest that this strategy may provide a new and potentially nonimmunogenic approach for targeted cancer chemotherapy.

Multiple event activation of a generic prodrug trigger by antibody catalysis.

Chemotherapeutic regimes are typically limited by nonspecific toxicity. To address this problem we have developed a broadly applicable drug-masking chemistry that operates in conjunction with a unique broad-scope catalytic antibody. This masking chemistry is applicable to a wide range of drugs because it is compatible with virtually any heteroatom. We demonstrate that generic drug-masking groups may be selectively removed by sequential retro-aldol-retro-Michael reactions catalyzed by antibody 38C2. This reaction cascade is not catalyzed by any known natural enzyme. Application of this masking chemistry to the anticancer drugs doxorubicin and camptothecin produced prodrugs with substantially reduced toxicity. These prodrugs are selectively unmasked by the catalytic antibody when it is applied at therapeutically relevant concentrations. We have demonstrated the efficacy of this approach by using human colon and prostate cancer cell lines. The antibody demonstrated a long in vivo half-life after administration to mice. Based on these findings, we believe that the system described here has the potential to become a key tool in selective chemotherapeutic strategies.

Asymmetric organic synthesis with catalytic antibodies.

The science of catalytic antibodies has undergone a rapid maturation process within its first nine years of existence. From initial 'proof of concept' and demonstration of fundamental, enzyme-like characteristics, antibodies have been shown to catalyze a remarkably broad scope of organic transformations, including difficult and unfavorable chemical reactions. Yet, the ultimate testing ground for new concepts in organic chemistry has always been the synthesis of natural products. Here we focus on several issues related to the applicability of antibody catalysis in organic synthesis. We show that (a) in the hydrophobic environment of the antibody active site, short-lived intermediates can be formed and reacted in a controlled way, thus allowing antibodies to catalyze reactions that are normally incompatible with aqueous media, (b) the intrinsic order of reactivity (chemoselectivity) in a series of structurally related enol ethers and ketals can be inverted from 1:10 in the uncatalyzed hydrolysis reaction to 1000:1 under antibody catalysis, and (c) an efficient total synthesis of alpha-multistriatin, an important, biologically active natural product can be achieved via antibody catalysis.

Using antibodies to perturb the coordination sphere of a transition metal complex.

Metal ions in the active sites of many metalloenzymes exhibit distinctive spectral and chemical features which are different from those of small inorganic complexes. These features are the result of the unusual geometric and electronic constraints that are imposed on the metal ion within the protein environment. Much effort has been invested to try to mimic this feature of metalloenzymes in synthetic systems, but this remains a formidable task. Here we show that one of the key lessons learned from the science of catalytic antibodies--that binding energy can be converted into chemical energy--can be exploited to 'fine-tune' the physicochemical properties of a metal complex. We show that an antibody's binding site can reversibly perturb the coordination geometry of a metal ion, and can stabilize a high-energy coordinated species. Specifically, antibodies designed to bind the organosilicon compound 1 also bind the geometrically similar Cu(I) complex 2. However, the antibody binds a slightly compressed form of 2, which is closer in size to 1. This distortion is manifested by a spectral shift--an 'immunochromic' effect.

Antibody catalysis of a reaction otherwise strongly disfavoured in water.

Several examples have been reported recently of antibody catalysis of reactions that are strongly disfavoured because of the high free energy of the transition state. Here we show that catalytic antibodies can be used to promote a particularly useful kind of reaction from a synthetic point of view: one involving an intermediate that is highly unstable in water. We show that an antibody elicited against the quaternary ammonium ion 4a (Fig. 1) catalyses the protonation of the enol ether 1 to form, with complete enantioselectivity, an oxocarbonium intermediate. This species is highly reactive in water, and would normally react with a water molecule to give the corresponding ketone 2. But the antibody provides a hydrophobic environment that allows the oxocarbonium ion instead to undergo an intramolecular reaction to form an enantiomerically pure ketal 3. This result shows that catalytic antibodies can exclude solvent molecules entirely from crucial steps on the reaction pathway.