Combined Lateral Plateau and PCL Injury in a Pediatric Patient: A Case Report.

Introduction: Posterior cruciate ligament (PCL) injuries and tibial plateau fractures are common orthopedic injuries. In the pediatric population, femoral-sided avulsions are the most common injury pattern for PCL injuries. However, there is limited literature on the characterization and treatment of pediatric PCL avulsion with concomitant tibial plateau fracture. Case Report: We present the case of an adolescent female who was involved in an all-terrain vehicle rollover. The patient sustained a femoral-sided PCL avulsion injury with an associated lateral tibial plateau fracture. The PCL avulsion was treated through arthroscopic cruciate repair, while the tibial plateau fracture was managed with open reduction and internal fixation (ORIF). Conclusion: This case report highlights a rare combination of a femoral-sided PCL avulsion and lateral tibial plateau fracture in a pediatric patient. The treatment involved arthroscopic cruciate repair for the PCL avulsion and ORIF for the tibial plateau fracture. Further studies are needed to establish optimal management strategies for similar cases.

Distal Ulna Fracture Fixation with the Specialized Threaded Pin.

Purpose: Distal ulna fractures can often be treated nonsurgically; however, many surgeons consider significant displacement or instability, especially following fixation of an associated distal radius fracture, an indication for surgical fixation because of potential problems associated with malunion of these fractures. Traditionally, these fractures have been addressed with plate fixation but hardware in this location is often prominent and associated with a high rate of symptomatic hardware and subsequent hardware removal. We proposed a method of intramedullary fixation using a specialized threaded pin. As this fixation is intramedullary, it avoids many of the problems associated with traditional surgical treatment methods for this fracture. We present a series of nine patients treated in this manner, all of whom had associated distal radius fractures. Methods: Preoperative and postoperative radiographs were reviewed, after which patients were contacted via phone. Patient-reported outcome measures, including QuickDASH and visual analog scale scores, were assessed. Results: The average QuickDASH score was 13.6 (range, 0-100), with a median of 9.1. Three patients reported occasional ulnar-sided wrist pain, with an average visual analog scale score of 1.3 (range, 0-10) and a median of 0.5. All patients returned to all activities except one patient who could not resume playing musical instruments because of stiffness. No patient required removal of the threaded pin, but one patient underwent removal of the radial volar plate. No other patients underwent secondary procedures. Conclusions: Threaded pin fixation is a viable alternative to existing options for distal ulnar neck fractures and may have an advantage over plate fixation because of a lack of hardware prominence. Type of study/level of evidence: Therapeutic IV.

Normal Values of the Second Interosseous Pinch: A Measurement of Pure Ulnar-Innervated Intrinsic Muscles of the Hand.

PURPOSE: The second palmar interosseous muscle is innervated solely by the ulnar nerve, and second palmar interosseous pinch (2IP) strength may be a good indicator of ulnar nerve motor function. The goal of this study was to describe the 2IP test and establish its normative values, stratified by age, sex, and dominance. METHODS: Volunteers were recruited to participate in this study at various community locations. Patients over the age of 18 years were eligible for this study. Demographic information on all subjects was collected. The volunteers were asked to pinch a hydraulic pinch gauge between the index and middle finger proximal phalanges with the proximal and distal interphalangeal joints flexed and without recruiting the thumb. Three 2IP measurements were taken for each hand. Descriptive statistics and analysis of covariance were performed to determine the effect of age, sex, dominance, and side on 2IP. We analyzed the 2IP strength using the 2IP test across 3 trials to determine whether it was affected by repeated testing. RESULTS: Two hundred thirty-eight patients met the inclusion criteria (45 ± 21 years, 55% women, 87% right-hand dominant). There was no statistically significant difference between dominant and nondominant hands or among the 3 trials. There was a statistically significant correlation between age and 2IP strength ranging between 0.32 and 0.44 kg. Age and sex showed a statistically significant association with 2IP strength, with patients of older age and women having weaker 2IP. CONCLUSIONS: We determined normative values for 2IP strength using a sample from a normal population. More studies are needed to validate these results. CLINICAL RELEVANCE: Second interosseous pinch strength may be a useful tool to assess ulnar nerve function.

Complications Associated with Administration of Post-operative Weight-Based Enoxaparin in Orthopaedic Trauma Patients.

Background In orthopedic-specific patients, limited evidence exists in regard to prophylactic weight-based enoxaparin dosing in the obese population. We examined the clinical outcomes of administering weight-based enoxaparin to obese orthopedic trauma patients. Methods This retrospective study involved 679 patients who underwent orthopedic trauma surgery and were admitted from 1/2016 to 6/2020 at a single institution. Of those patients, 156 patients met our inclusion criteria. Inclusion criteria included BMI>35 kg/m2 and received weight-based enoxaparin post-operatively (defined as any singular dose >40 mg at any time). Blood transfusion, documented hematoma, deep vein thrombosis (DVT), and return visits to the OR after the administration of weight-based enoxaparin were the primary endpoints assessed. Age, BMI, weight, injury severity score (ISS), sex, post-operative time to the first dose of enoxaparin, the total daily dose of enoxaparin, operating room (OR) blood loss, OR time, patient co-morbidities, and pre/post-operative hemoglobin were evaluated for a potential relationship with the primary endpoints. Results One hundred and eighty-five surgeries were performed on a total of 156 patients. Thirty-six of the 185 (19%) surgeries required post-operative blood transfusion after weight-based enoxaparin was given. Higher ISS score, lower pre-operative hemoglobin, and lower post-operative hemoglobin were significant predictors of blood transfusion. Only increased post-operative time to the first dose of enoxaparin was significantly associated with DVT formation. Thirteen of the 156 patients (8.3%) had a post-operative hematoma after administration of enoxaparin, and four of the 13 patients required return to the OR for bleeding complications. ISS was the only significant predictor of post-operative hematoma formation. Conclusion Patients with a higher injury severity score are at an increased risk of adverse bleeding and may benefit from lower doses of enoxaparin administered earlier post-operatively.

Arabidopsis HIPP proteins regulate endoplasmic reticulum-associated degradation of CKX proteins and cytokinin responses.

Eukaryotic organisms are equipped with quality-control mechanisms that survey protein folding in the endoplasmic reticulum (ER) and remove non-native proteins by ER-associated degradation (ERAD). Recent research has shown that cytokinin-degrading CKX proteins are subjected to ERAD during plant development. The mechanisms of plant ERAD, including the export of substrate proteins from the ER, are not fully understood, and the molecular components involved in the ERAD of CKX are unknown. Here, we show that heavy metal-associated isoprenylated plant proteins (HIPPs) interact specifically with CKX proteins synthesized in the ER and processed by ERAD. CKX-HIPP protein complexes were detected at the ER as well as in the cytosol, suggesting that the complexes involve retrotranslocated CKX protein species. Altered CKX levels in HIPP-overexpressing and higher-order hipp mutant plants suggest that the studied HIPPs control the ERAD of CKX. Deregulation of CKX proteins caused corresponding changes in the cytokinin signaling activity and triggered typical morphological cytokinin responses. Notably, transcriptional repression of HIPP genes by cytokinin indicates a feedback regulatory mechanism of cytokinin homeostasis and signaling responses. Moreover, loss of function of HIPP genes constitutively activates the unfolded protein response and compromises the ER stress tolerance. Collectively, these results suggests that HIPPs represent novel functional components of plant ERAD.

Arthroscopic Biceps to Subscapularis Tenodesis: A Surgical Technique.

A wide variety of techniques are available for tenodesis of the long head of the biceps tendon, and current literature does not favor any one in particular. We present a simple method for arthroscopic soft tissue biceps tenodesis that uses the subscapularis tendon as the anchor. This 5-step technique is time-efficient, technically simple, cost effective, and does not require powered instruments or specialized implants.

Excision of a Rare Triquetral Body Fracture Nonunion.

Aside from the more common dorsal avulsion fractures, isolated triquetral body fractures are a rare injury and often missed. When they are identified, conservative treatment via immobilization is often the standard of care for initial treatment. Rarely, triquetral body fractures can develop into symptomatic nonunions, causing considerable pain and disability. Multiple classification schemes have been described to categorize triquetrum fractures; however, distal triquetrum fractures fit into none of the established models. There is scarce literature describing treatment of triquetral body fracture nonunions. The few reports that exist often use a variation of open reduction internal fixation with or without grafting as treatment. We present the case of an unusual triquetral body fracture nonunion that was successfully treated via surgical excision of the ununited distal fragment.

The Cytokinin Oxidase/Dehydrogenase CKX1 Is a Membrane-Bound Protein Requiring Homooligomerization in the Endoplasmic Reticulum for Its Cellular Activity.

Degradation of the plant hormone cytokinin is controlled by cytokinin oxidase/dehydrogenase (CKX) enzymes. The molecular and cellular behavior of these proteins is still largely unknown. In this study, we show that CKX1 is a type II single-pass membrane protein that localizes predominantly to the endoplasmic reticulum (ER) in Arabidopsis (Arabidopsis thaliana). This indicates that this CKX isoform is a bona fide ER protein directly controlling the cytokinin, which triggers the signaling from the ER. By using various approaches, we demonstrate that CKX1 forms homodimers and homooligomers in vivo. The amino-terminal part of CKX1 was necessary and sufficient for the protein oligomerization as well as for targeting and retention in the ER. Moreover, we show that protein-protein interaction is largely facilitated by transmembrane helices and depends on a functional GxxxG-like interaction motif. Importantly, mutations rendering CKX1 monomeric interfere with its steady-state localization in the ER and cause a loss of the CKX1 biological activity by increasing its ER-associated degradation. Therefore, our study provides evidence that oligomerization is a crucial parameter regulating CKX1 biological activity and the cytokinin concentration in the ER. The work also lends strong support for the cytokinin signaling from the ER and for the functional relevance of the cytokinin pool in this compartment.

Occult Iliac Deep Vein Thrombosis in Second Trimester Pregnancy: Clues on Bedside Ultrasound.

Isolated pelvic deep vein thromboses (DVT) are rare and difficult to diagnose, but they are more common in pregnant women and carry an increased risk of embolization. Pulmonary embolism is the most common non-obstetric cause of death in pregnancy. Compression ultrasound is the first-line imaging test for suspected lower extremity DVT, but it cannot usually aid in directly visualizing or easily diagnosing isolated pelvic DVT. Nonetheless, point-of-care ultrasound (POCUS) may provide valuable clues to help rule in pelvic DVT and expedite initiation of anticoagulant therapy. Such findings include increased venous diameter, increased resistance to compression, visible venous reflux, and blunted phasicity. This case presents an example of how these findings on POCUS led the emergency physician to make the difficult diagnosis of pelvic DVT at the bedside within seconds.

Structure Elucidation of Poly-Faldaprevir: Polymer Backbone Solved Using Solid-State and Solution Nuclear Magnetic Resonance Spectroscopy.

A large-scale synthesis of the hepatitis C virus drug Faldaprevir revealed precipitation of an unknown insoluble solid from methanol solutions of the drug substance. The unknown impurity was determined to be a polymer of Faldaprevir based on analytical methods that included size exclusion chromatography in combination with electrospray ionization mass spectrometry, solution nuclear magnetic resonance (NMR), matrix-assisted laser desorption ionization-time of flight, ultracentrifugation, elemental analysis, and sodium quantitation by atom absorption spectroscopy. Structure elucidation of the polymeric backbone was achieved using solid-state NMR cross-polarization/magic angle spinning (CP/MAS), cross polarization-polarization inversion, and heteronuclear correlation (HETCOR) experiments. The polymerization was found to occur at the vinyl cyclopropane via a likely free radical initiation mechanism. Full proton and carbon chemical shift assignments of the polymer were obtained using solution NMR spectroscopy. The polymer structure was corroborated with chemical synthesis of the polymer and solution NMR analysis.

Endoplasmic reticulum: Where nucleotide sugar transport meets cytokinin control mechanisms.

The endoplasmic reticulum (ER) is a multifunctional eukaryotic organelle where the vast majority of secretory proteins are folded and assembled to achieve their correct tertiary structures. The lumen of the ER and Golgi apparatus also provides an environment for numerous glycosylation reactions essential for modifications of proteins and lipids, and for cell wall biosynthesis. These glycosylation reactions require a constant supply of cytosolically synthesized substrate precursors, nucleotide sugars, which are transported by a group of dedicated nucleotide sugar transporters (NST). Recently, we have reported on the identification of a novel ER-localized NST protein, ROCK1, which mediates the transport of UDP-linked acetylated hexosamines across the ER membrane in Arabidopsis. Interestingly, it has been demonstrated that the activity of ROCK1 is important for the regulation of cytokinin-degrading enzymes, cytokinin oxidases/dehydrogenases (CKX), in the ER and, thus, for cytokinin responses. In this addendum we will address the biochemical and cellular activity of the ROCK1 transporter and its phylogenetic relation to other NST proteins.

Arabidopsis ROCK1 transports UDP-GlcNAc/UDP-GalNAc and regulates ER protein quality control and cytokinin activity.

The formation of glycoconjugates depends on nucleotide sugars, which serve as donor substrates for glycosyltransferases in the lumen of Golgi vesicles and the endoplasmic reticulum (ER). Import of nucleotide sugars from the cytosol is an important prerequisite for these reactions and is mediated by nucleotide sugar transporters. Here, we report the identification of REPRESSOR OF CYTOKININ DEFICIENCY 1 (ROCK1, At5g65000) as an ER-localized facilitator of UDP-N-acetylglucosamine (UDP-GlcNAc) and UDP-N-acetylgalactosamine (UDP-GalNAc) transport in Arabidopsis thaliana. Mutant alleles of ROCK1 suppress phenotypes inferred by a reduced concentration of the plant hormone cytokinin. This suppression is caused by the loss of activity of cytokinin-degrading enzymes, cytokinin oxidases/dehydrogenases (CKXs). Cytokinin plays an essential role in regulating shoot apical meristem (SAM) activity and shoot architecture. We show that rock1 enhances SAM activity and organ formation rate, demonstrating an important role of ROCK1 in regulating the cytokinin signal in the meristematic cells through modulating activity of CKX proteins. Intriguingly, genetic and molecular analysis indicated that N-glycosylation of CKX1 was not affected by the lack of ROCK1-mediated supply of UDP-GlcNAc. In contrast, we show that CKX1 stability is regulated in a proteasome-dependent manner and that ROCK1 regulates the CKX1 level. The increased unfolded protein response in rock1 plants and suppression of phenotypes caused by the defective brassinosteroid receptor bri1-9 strongly suggest that the ROCK1 activity is an important part of the ER quality control system, which determines the fate of aberrant proteins in the secretory pathway.

Room temperature reversible hydrogen storage in polyaniline (PANI) nanofibers.

We report for the first time the reversible hydrogen storage behavior at room temperature in polyaniline nanofibers. The rate of hydrogen sorption during the initial run was very rapid and an extended plateau pressure of about 30 bars was obtained from the pressure-composition isotherm profiles of these polyaniline nanofibers. The reversible cycling capacity of approximately 3-4 wt% was demonstrated at room temperature and has been attributed to the unique nanofibrous microstructural and surface properties.