Efficacy of radial styloid targeting screws in volar plate fixation of intra-articular distal radial fractures: a biomechanical study in a cadaver fracture model

<p>Abstract</p> <p>Background</p> <p>The locking screws target the radial styloid, theoretically provide greater stability against radial styloid fragment. However, it is unknown whether the radial styloid locking screws increased the stability of the volar plating system fixation along the entire distal radius or not. In this study, we evaluated the stability of the volar plating system fixation with or without the radial styloid screws using a biomechanical study in a cadaver fracture model.</p> <p>Methods</p> <p>Six matched pairs of fresh-frozen human cadaver wrists complete from the proximal forearm to the metacarpal bones were prepared to simulate standardized 3-part intra-articular and severe comminuted fractures. Specimens were fixed using the volar plating system with or without 2 radial styloid screws. Each specimen was loaded at a constant rate of 20 mm/min to failure. Load data was recorded and, ultimate strength and change in gap between distal and proximal fragments were measured. Data for ultimate strength and screw failure after failure loading were compared between the 2 groups.</p> <p>Results</p> <p>The average ultimate strength at failure of the volar plate fixation with radial styloid screws (913.5 ± 157.1 N) was significantly higher than that without them (682.2 ± 118.6 N). After failure loading, the average change in gap between the ulnar and proximal fragment was greater than that between the radial and proximal fragment. The number of bent or broken screws in ulnar fragment was higher than that in radial fragment. The number of specimens with bent or broken screws in cases with radial styloid screws was fewer than that in the fixation without radial styloid screws group.</p> <p>Conclusion</p> <p>The ulnar fragment is more intensively stressed than the radial fragment under axial loading of distal radius at full wrist extension. The radial styloid screws were effective in stable volar plate fixation of distal radial fractures.</p

L-Ascorbate Biosynthesis Involves Carbon Skeleton Rearrangement in the Nematode Caenorhabditis elegans

Ascorbate (AsA) is required as a cofactor and is widely distributed in plants and animals. Recently, it has been suggested that the nematode Caenorhabditis elegans also synthesizes AsA. However, its biosynthetic pathway is still unknown. To further understand AsA biosynthesis in C. elegans, we analyzed the incorporation of the 13C atom into AsA using gas chromatography-mass spectrometry (GC-MS) in worms fed with D-Glc (1-13C)-labeled Escherichia coli. GC-MS analysis revealed that AsA biosynthesis in C. elegans, similarly to that in mammalian systems, involves carbon skeleton rearrangement. The addition of L-gulono-1,4-lactone, an AsA precursor in the mammalian pathway, significantly increased AsA level in C. elegans, whereas the addition of L-galactono-1,4-lactone, an AsA precursor in the plant and Euglena pathway, did not affect AsA level. The suppression of E03H4.3 (an ortholog of gluconolactonase) or the deficiency of F54D5.12 (an ortholog of L-gulono-1,4-lactone oxidase) significantly decreased AsA level in C. elegans. Although N2- and AsA-deficient F54D5.12 knockout mutant worm (tm6671) morphologies and the ratio of collagen to non-collagen protein did not show any significant differences, the mutant worms exhibited increased malondialdehyde levels and reduced lifespan compared with the N2 worms. In conclusion, our findings indicate that the AsA biosynthetic pathway is similar in C. elegans and mammals

Intra-cardiac echocardiography guided catheter ablation of a right posterior accessory pathway in a patient with Ebstein׳s anomaly

AbstractWe report a case of Ebstein׳s anomaly in which radiofrequency catheter ablation of an accessory pathway was successfully performed under intra-cardiac echocardiography. A 50-year-old woman was referred to our hospital for radiofrequency catheter ablation of a paroxysmal supraventricular tachycardia. A 12-lead surface electrocardiogram revealed ventricular pre-excitation associated with type B Wolff–Parkinson–White syndrome. In the baseline electrophysiological study, an orthodromic atrioventricular reciprocating tachycardia with a right posterior accessory pathway was induced. A phased-array intra-cardiac echo probe was positioned in the right atrium to visualize the atrioventricular junction. The key structures for catheter ablation, such as the atrialized right ventricle, atrioventricular junction, and tricuspid valve, were clearly visualized on intra-cardiac echocardiography. Radiofrequency current was successfully delivered at the atrioventricular junction, where a Kent potential was recorded. During a 6-month follow-up period, the patient was free from arrhythmias. The findings in this case suggest that phased-array intra-cardiac echocardiography is useful for ablation of right-sided accessory pathways in patients with Ebstein׳s anomaly

The Surgical Benefits of Repeat Hepatectomy for Colorectal Liver Metastasis

The most common site of distant metastasis from colorectal cancer is the liver, and hepatectomy presents the best curative treatment for recurrence of colorectal liver metastasis （CRLM）. This study aimed to identify factors of prognostic value for repeat hepatectomy for CRLM and to determine whether a third such procedure could similarly produce favourable outcomes for CRLM. We analyzed data for 161 patients in our department with colorectal metastasis. Of these, 22 patients underwent repeat hepatectomy for recurrent metastasis, with 16 undergoing a second hepatectomy and 6 a third hepatectomy. We analyzed patient characteristics, tumor status, operation-related variables, and short- and long-term outcomes. Univariate analysis for repeat hepatectomy identified the following five prognostic risk factors: T factor （＞SE） of the primary cancer, number of tumors involved in the initial hepatectomy （＞5）, interval from first to second hepatectomy （＜1year）, number of tumors involved in second hepatectomy （＞3）, and post-operation time （＞30days）. By multivariate analysis, T factor （＞SE） of the primary cancer, number of tumors in the initial hepatectomy （＞5）, and number of tumors in the second hepatectomy （＞3） were independently associated with a worse survival after surgery for CRLM. Although surgical outcomes of the third hepatectomy were not compared with those of the first and second hepatectomy, there were no obvious differences, nor did the 1-, 3-, and 5-year survival rates differ significantly among the three groups. Repeat hepatectomy for CRLM could improve long-term survival. In addition, patients undergoing a third hepatectomy showed a similar survival benefit to those having one or two resections

Visualization of the radiofrequency lesion after pulmonary vein isolation using delayed enhancement magnetic resonance imaging fused with magnetic resonance angiography

AbstractBackgroundThe radiofrequency (RF) lesions for atrial fibrillation (AF) ablation can be visualized by delayed enhancement magnetic resonance imaging (DE-MRI). However, the quality of anatomical information provided by DE-MRI is not adequate due to its spatial resolution. In contrast, magnetic resonance angiography (MRA) provides similar information regarding the left atrium (LA) and pulmonary veins (PVs) as computed tomography angiography. We hypothesized that DE-MRI fused with MRA will compensate for the inadequate image quality provided by DE-MRI.MethodsDE-MRI and MRA were performed in 18 patients who underwent AF ablation (age, 60±9 years; LA diameter, 42±6mm). Two observers independently assessed the DE-MRI and DE-MRI fused with MRA for visualization of the RF lesion (score 0–2; where 0: not visualized and 2: excellent in all 14 segments of the circular RF lesion).ResultsDE-MRI fused with MRA was successfully performed in all patients. The image quality score was significantly higher in DE-MRI fused with MRA compared to DE-MRI alone (observer 1: 22 (18, 25) vs 28 (28, 28), p<0.001; observer 2: 24 (23, 25) vs 28 (28, 28), p<0.001).ConclusionsDE-MRI fused with MRA was superior to DE-MRI for visualization of the RF lesion owing to the precise information on LA and PV anatomy provided by DE-MRI