Next generation fibroblast activation protein (FAP) targeting PET tracers - The tetrazine ligation allows an easy and convenient way to 18F-labeled (4-quinolinoyl)glycyl-2-cyanopyrrolidines

Small-molecular fibroblast activation protein inhibitor (FAPI)-based tracer have been shown to be promising Positron Emission Tomography (PET) 68Ga-labeled radiopharmaceuticals to image a variety of tumors including pancreatic, breast, and colorectal cancers, among others. In this study, we developed a novel 18F-labeled FAPI derivative. [18F]6 was labeled using a synthon approach based on the tetrazine ligation. It showed subnanomolar affinity for the FAP protein and a good selectivity profile against known off-target proteases. Small animal PET studies revealed high tumor uptake and good target-to-background ratios. [18F]6 was excreted via the liver. Overall, [18F]6 showed promising characteristics to be used as a PET tracer and could serve as a lead for further development of halogen-based theranostic FAPI radiopharmaceuticals.

Squaric Acid-Based Radiopharmaceuticals for Tumor Imaging and Therapy

Targeting vectors bound to a chelator represent a significant fraction of radiopharmaceuticals used nowadays for diagnostic and therapeutic purposes in nuclear medicine. The use of squaramides as coupling units for chelator and targeting vector helps to circumvent the disadvantages of several common coupling methods. This review gives an overview of the use of squaric acid diesters (SADE) as linking agents. It focuses on the conjugation of cyclic chelators, e.g., DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), as well as hybrid chelators like AAZTA⁵ (6-pentanoic acid-6-amino-1,4-diazepine tetracetic acid) or DATA^5m (6-pentanoic acid-6-amino-1,4-diazapine-triacetate) to different targeting vectors, e.g., prostate-specific membrane antigen inhibitors (KuE; PSMAi), fibroblast activation protein inhibitors (FAPi), and monoclonal antibodies (mAbs). An overview of the synthesis, radiolabeling, and in vitro and in vivo behavior of the described structures is given. The unique properties of SADE enable a fast and simple conjugation of chelators to biomolecules, peptides, and small molecules under mild conditions. Furthermore, SA-containing conjugates could not only display similar in vitro characteristics in terms of binding affinity when compared to reference compounds, but may even induce beneficial effects on the pharmacokinetic properties of these radiopharmaceuticals.

Does collagenase injection disrupt or digest the Dupuytren's cord: a magnetic resonance imaging study

Collagenase clostridium histolyticum has been extensively studied as a treatment modality for Dupuytren's contracture. Its mechanism of action has been documented. It is unknown whether injected collagenase weakens the Dupuytren's cord sufficiently to cause failure during manipulation or if there is digestion and reduction in cord volume. We examined five patients with isolated contractures of the ring or middle metacarpalphalangeal (MP) joint using magnetic resonance imaging (MRI) prior to injection with collagenase and again 1 month following injection. All patients had full correction after manipulation which was maintained at follow-up. The Dupuytren's cord was evaluated with respect to volume, signal intensity, inflammatory changes and continuity. Additionally, signal intensity changes of the flexor tendons and neurovascular structures were recorded. MRI demonstrated cord discontinuity, significant reduction of cord volume and a significant increase in cord signal intensity after treatment with collagenase. There was a slight increase in flexor tendon signal intensity that was not significant. These findings suggest that there may be local chemical dissolution of the cord. Future studies may establish whether or not this will have prognostic implications in terms of correction and recurrence following collagenase injection.

LEVEL OF EVIDENCE

IV.

The effect of anteroposterior laxity on the range of movement and knee function following a cruciate-retaining total knee replacement

The amount of anteroposterior laxity required for a good range of movement and knee function in a cruciate-retaining total knee replacement (TKR) continues to be debated. We undertook a retrospective study to evaluate the effects of anteroposterior laxity on the range of movement and knee function in 55 patients following the e-motion cruciate-retaining TKR with a minimum follow-up of two years. The knees were divided into stable (anteroposterior translation, < or = 10 mm, 38 patients) and unstable (anteroposterior translation, > 10 mm, 17) groups based on the anteroposterior laxity, measured using stress radiographs. We compared the Hospital for Special Surgery (HSS) scores, the Western Ontario MacMasters University Osteoarthritis (WOMAC) index, weight-bearing flexion, non-weight-bearing flexion and the reduction of flexion under weight-bearing versus non-weight-bearing conditions, which we referred to as delta flexion, between the two groups at the final follow-up. There were no differences between the stable and unstable groups with regard to the mean HHS and WOMAC total scores, as well as weight-bearing and non-weight-bearing flexion (p = 0.277, p = 0.082, p = 0.095 and p = 0.646, respectively). However, the stable group had a better WOMAC function score and less delta flexion than the unstable group (p = 0.011 and p = 0.005, respectively). Our results suggest that stable knees with laxity < or = 10 mm have a good functional outcome and less reduction of flexion under weight-bearing conditions than unstable knees with laxity > 10 mm following an e-motion cruciate-retaining TKR.

A case of carpal tunnel syndrome due to dialysis-related amyloidosis in a patient undergoing long-term hemodialysis

Carpal tunnel syndrome (CTS) is characterized by burning pain, numbness and tingling sensation in the thumb, index and middle fingers and the lateral half of the palm and progressive atrophy of the thenar muscles by compression of the median nerve within the carpal tunnel due to a variety of etiologic factors. Surgical intervention usually successfully relieves symptoms of CTS. Recently CTS has been regarded as one of the major clinical manifestations of dialysis-related amyloidosis due to beta 2-microglobulin deposition and recognized with increasing frequency in patients undergoing long-term hemodialysis. We report a case of carpal tunnel syndrome due to dialysis-related amyloidosis in patients undergoing long-term hemodialysis, confirmed by electromyography and biopsy in transverse carpal ligament and median nerve.

Below knee stump reconstruction by turn-up technique. Report of 2 cases

In cases of persistent recurrence of tumor or intractable infection affecting the proximal half of the tibia, knee disarticulation or short below knee amputation is sometimes inevitable. If the knee joint is lost, rehabilitation is very difficult and sometimes impossible to attain in terms of active normal daily living. A new technique was designed for reconstruction of the stump following below knee amputation after en bloc resection of the proximal 2/3 of the tibia that included turn-up of the distal composite graft to 180 degrees and rigid fixation. It was applied to 2 cases. The followup showed excellent results in both cases.

Bent plate fixation in combined intertrochanteric and subtrochanteric fractures of the femur

Twenty-five combined intertrochanteric and subtrochanteric fractures of the femur (Type IV of Kyle's or Type V of Seinsheimer's classification) were treated with a bent plate and followed up through union (average: 2 years). All of the patients received immediate supplementary bone grafting and additional external supports. All but one of the fractures united between 3 and 6 months. Complications were: delayed union (1 case), which was treated by bone graft, trochanteric bursitis (3), and mild coxa vara (2). Anatomical reduction of scattered fragments and its maintenance through bony union were achieved in all cases. The bent plate provided excellent fixation in combined intertrochanteric and subtrochanteric fracture of the femur, and could be a successful alternative for these combined fractures.