Rhodium catalysed conversion of carbenes into ketenes and ketene imines using PNN pincer complexes

PNN pincer-type rhodium complexes catalyze ketene and ketene imine synthesis, using CO or an isocyanide and a carbene precursor.

Intermolecular C–H activation with an Ir-METAMORPhos piano-stool complex – multiple reaction steps at a reactive ligand

Reaction of phenylacetylene with an Ir^III(METAMORPhos) complex generates a unique four-membered IrPNC metallacyclic species with an exocyclic CC fragment.

Late enhanced computed tomography in Hypertrophic Cardiomyopathy enables accurate left-ventricular volumetry

OBJECTIVES

Late enhancement (LE) multi-slice computed tomography (leMDCT) was introduced for the visualization of (intra-) myocardial fibrosis in Hypertrophic Cardiomyopathy (HCM). LE is associated with adverse cardiac events. This analysis focuses on leMDCT derived LV muscle mass (LV-MM) which may be related to LE resulting in LE proportion for potential risk stratification in HCM.

METHODS

N=26 HCM-patients underwent leMDCT (64-slice-CT) and cardiovascular magnetic resonance (CMR). In leMDCT iodine contrast (Iopromid, 350 mg/mL; 150mL) was injected 7 minutes before imaging. Reconstructed short cardiac axis views served for planimetry. The study group was divided into three groups of varying LV-contrast. LeMDCT was correlated with CMR.

RESULTS

The mean age was 64.2 ± 14 years. The groups of varying contrast differed in weight and body mass index (p < 0.05). In the group with good LV-contrast assessment of LV-MM resulted in 147.4 ± 64.8 g in leMDCT vs. 147.1 ± 65.9 in CMR (p > 0.05). In the group with sufficient contrast LV-MM appeared with 172 ± 30.8 g in leMDCT vs. 165.9 ± 37.8 in CMR (p > 0.05). Overall intra-/inter-observer variability of semiautomatic assessment of LV-MM showed an accuracy of 0.9 ± 8.6 g and 0.8 ± 9.2 g in leMDCT. All leMDCT-measures correlated well with CMR (r > 0.9).

CONCLUSIONS

LeMDCT primarily performed for LE-visualization in HCM allows for accurate LV-volumetry including LV-MM in > 90% of the cases.

KEY POINTS

• LeMDCT of relatively low contrast allows for LV planimetry in HCM. • The correlation of leMDCT-based LV volumetry with gold-standard CMR was excellent (r > 0.9). • LeMDCT requires approximately 2.0mL/kgBW of dye to achieve acceptable contrast.

Pressure distribution in carpometacarpal joint, due to step-off in operatively treated Bennett's fractures

INTRODUCTION

The purpose of the current study was to investigate the effects of residual articular incongruity after Bennett's fracture on load distribution of the joint surface. Our aim was to investigate whether a residual joint step and the altered load distribution led to negative clinical outcomes or symptomatic degenerative osteoarthritis of the trapeziometacarpal joint.

PATIENTS AND METHODS

Twenty-four patients were available for long-term follow-up examination and were contacted by phone, and they returned for follow-up examination. Computed tomography (CT) scans of both carpometacarpal (CMC) joints were performed. CT scans were taken in the sagittal plane of the forearms with a slice thickness of 0.625 mm for three-dimensional reconstruction. The CMC joints were analysed due to a residual step in the joint. Only patients with a residual step-off were included in this study. To determine the areas of maximum density in the joint, CT-osteoabsorptiometry was performed.

RESULTS

Ten patients had the maximum loading area radial and two patients central. The second major position of mineralization was detected central in four patients, volar-ulnar in two patients, radial in one patient, dorso-radial in one patient, volar in one patient and volar-radial in two patients.

CONCLUSION

Finally, no higher loading in the area of the beak fragment could be found. The Wagner technique, even if it results in a persistent 1-2-mm intra-articular step-off of the beak fragment, is still the favourable method for the treatment of Bennett's luxation fractures.

A new radiological method to detect dorsally penetrating screws when using volar locking plates in distal radial fractures. The dorsal horizon view

Penetration of the dorsal screw when treating distal radius fractures with volar locking plates is an avoidable complication that causes lesions of the extensor tendon in between 2% and 6% of patients. We examined axial fluoroscopic views of the distal end of the radius to observe small amounts of dorsal screw penetration, and determined the ideal angle of inclination of the x-ray beam to the forearm when making this radiological view. Six volar locking plates were inserted at the wrists of cadavers. The actual screw length was measured under direct vision through a dorsal approach to the distal radius. Axial radiographs were performed for different angles of inclination of the forearm at the elbow. Comparing axial radiological measurements and real screw length, a statistically significant correlation could be demonstrated at an angle of inclination between 5° and 20°. The ideal angle of inclination required to minimise the risk of implanting over-long screws in a dorsal horizon radiological view is 15°.

Clinical and biomechanical investigation of an increased articular cavity depth after distal radius fractures: effect on range of motion, osteoarthrosis and loading patterns

INTRODUCTION

After fracture, distal radius malunion with dissociation of the volar and dorsal ulnar fracture fragments can lead to an increased articular cavity.

PATIENTS AND METHODS

To investigate its clinical impact we retrospectively analyzed the outcome of 81 patients and simulated this form of malunion in a biomechanical experiment with six cadaver specimens in a dynamic loading set-up.

RESULTS

In clinics, a higher arthritis stage was significantly correlated with an increased articular cavity depth and an increased anterioposterior distance. In cadaver specimens, a significantly decreased range of motion and significantly altered intraarticular contact characteristics were recognized for an increased cavity.

CONCLUSION

Alterations in contact biomechanics could be one reason for the higher incidence of posttraumatic osteoarthritis when a deeper central impaction of the distal radius is present. From a clinical and experimental point of view, restoration of the normal shape of the distal radius is considered to minimize the risk for posttraumatic radiocarpal osteoarthritis.

FOXO4 is necessary for neural differentiation of human embryonic stem cells

Proteostasis is critical for maintaining cell function and proteome stability may play an important role in human embryonic stem cell (hESC) immortality. Notably, hESC populations exhibit a high assembly of active proteasomes, a key node of the proteostasis network. FOXO4, an insulin/IGF-1 responsive transcription factor, regulates proteasome activity in hESCs. We find that loss of FOXO4 reduces the potential of hESCs to differentiate into neural lineages. Therefore, FOXO4 crosses evolutionary boundaries and links hESC function to invertebrate longevity modulation.