Magnetic resonance imaging of the elbow: update on current techniques and indications

The utility of magnetic resonance imaging of the elbow has noticeably improved over the past decade. Advances in equipment and refinement of pulse sequences has allowed for superior visualization of many pathologic processes involving the elbow joint and its surrounding structures. At this time, magnetic resonance imaging is most valuable in detecting occult fractures, osteochondritis dissecans, collateral ligament tears, nonossified intra-articular loose bodies, and soft tissue masses. It may also aid in the diagnosis of tendinous injuries, compression neuropathies, and synovial disorders. This article serves as an educational update for hand surgeons and illustrates the features of normal anatomy and specific disorders of the elbow.     

Stem cell therapy in spinal trauma: Does it have scientific validity?

Stem cell-based interventions aim to use special regenerative cells (stem cells) to facilitate neuronal function beyond the site of the injury. Many studies involving animal models of spinal cord injury (SCI) suggest that certain stem cell-based therapies may restore function after SCI. Currently, in case of spinal cord injuries, new discoveries with clinical implications have been continuously made in basic stem cell research, and stem cell-based approaches are advancing rapidly toward application in patients. There is a huge base of preclinical evidence in vitro and in animal models which suggests the safety and clinical efficacy of cellular therapies after SCI. Despite this, data from clinical studies is not very encouraging and at times confounding. Here, we have attempted to cover preclinical and clinical evidence base dealing with safety, feasibility and efficacy of cell based interventions after SCI. The limitations of preclinical data and the reasons underlying its failure to translate in a clinical setting are also discussed. Based on the evidence base, it is suggested that a multifactorial approach is required to address this situation. Need for standardized, stringently designed multi-centric clinical trials for obtaining validated proof of evidence is also highlighted.     

Activated abl oncogenes and apoptosis: differing responses of transformed myeloid progenitor cell lines

Activation of the c-abl protooncogene occurs during the generation of both the Abelson murine leukemia virus and the bcrabl fusion gene. To further dissect the biological properties of these proteins, we studied their effect on apoptosis. Using dimethyl sulfoxide (DMSO) to induce apoptosis in the murine myeloid progenitor cell line 32Dcl3, we examined the effect of expression of both v-abl and bcrabl transgenes on apoptosis. v-abl expressing 32Dcl3 cells are sensitive to apoptosis induction, similar to parental 32Dcl3 cells. In contrast, bcrabl expression 32Dcl3 cells are protected from the apoptotic stimulus resulting from DMSO exposure. Analyzing the expression patterns for Bcl- 2 and Bax, two proteins known to modulate the apoptotic response, we found a downregulation of Bcl-2 and enhanced expression of Bax in 32Dcl3 cells. In 32Dcl3/v-Abl cells, Bcl-2 expression remained constant while Bax was upregulated, whereas in 32Dcl3 cells expressing bcrabl, there was continuous expression of Bcl-2 at a level greater than observed in v-abl transformed cells. Taken together, our data demonstrate that although both activated abl gene products promote overlapping effects of some biological responses (i.e., factor- independent proliferation) they diverge in their effect on apoptotic signaling pathways.     

Polymerase chain reaction-based diagnosis of del (5q) in acute myeloid leukemia and myelodysplastic syndrome identifies a minimal deletion interval

Loss of all or part of the long arm of human chromosome 5 is a recurrent abnormality in patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), especially after chemotherapy for a prior malignancy. It is one of the worst prognostic indicators in AML, associated with chemotherapy resistance and short survival. These deletions center at band 5q31, which has thus been proposed as the location of a tumor suppressor gene; this site is to be distinguished from that observed in 5q- syndrome, centering at 5q32. To define the molecular extent and the clinical prevalence of 5q31 deletions, we collected a series of AML and MDS cases of mixed karyotype, taking care to exclude MDS cases with 5q- syndrome. The samples were analyzed for loss of heterozygosity (LOH) using a panel polymerase chain reaction (PCR)-based microsatellite markers from 5q, comparing malignant cells with normal tissue derived from lymphoblastoid cell lines or buccal mucosa scrapings. Losses were detected in seven of 29 matched samples, including four of 17 with MDS, and three of 12 with AML; six of these seven also had a cytogenetically-visible del(5q) or -5. The one case without a cytogenetic deletion showed molecular loss of three contiguous markers, with retention of flanking markers interleukin-9 (IL-9) and D5S414, and thus contained a small deletion that is below cytogenetic resolution. PCR failed to detect 5q loss in two cases with large cytogenetic deletions, but both had been treated and contained low percentages of malignant cells in the samples. This study thus led to the identification of a case with a minimal deletion for the 5q31 tumor suppressor gene, specified by IL-9-D5S414, that is approximately 1 Mb (2 cM) in extent. Additionally, we demonstrate that PCR-based allelotyping is a reliable method for the detection of chromosomal deletion in myeloid malignancy, providing the specimens contain a high proportion of malignant cells. These studies will help to identify the tumor-suppressor gene at 5q31, and will help to develop molecular methods for diagnosis and monitoring of these disorders.     

Late endocarditis of Amplatzer atrial septal occluder device in a child

Bacterial endocarditis following atrial septal defect closure using Amplatzer device in a child is extremely rare. We report a 10-year-old girl who developed late bacterial endocarditis, 6 years after placement of an Amplatzer atrial septal occluder device. Successful explantation of the device and repair of the resultant septal defect was carried out using a homograft patch. The rare occurrence of this entity prompted us to highlight the importance of long-term follow up, review the management and explore preventive strategies for similar patients who have multiple co-morbidities and a cardiac device. A high index of suspicion is warranted particularly in pediatric patients.     

香港大学玛丽医院脑内科临床运作模式浅析

玛丽医院是香港最好的公立医院,患者享受几乎全免费的诊疗。脑内科的临床运作模式,可基本代表香港医疗体系的特点。医护和辅助人员都具有高度的责任感,各司其职,注重科室间的交流与合作,主动进行医患沟通。诊疗常规严格遵循最新的临床指南,紧跟循证医学证据。病例数少而精,随访出成果。     

Diffusion-weighted MR neurography of median and ulnar nerves in the wrist and palm

Objectives

To investigate the feasibility of diffusion-weighted magnetic resonance neurography (DW-MRN) in the visualisation of extremity nerves in the wrist and palm.

Methods

Thirty-two volunteers and 21 patients underwent imaging of the wrist and palm on a 3-T MR scanner. In all subjects, two radiologists evaluated the image quality on DW-MRN using a four-point grading scale. Kappa statistics were obtained for inter-observer performance. In volunteers, the chi-squared test was used to assess the differences in nerve visualisation on DW-MRN and axial fat-suppressed proton density weighted imaging (FS-PDWI).

Results

In volunteers, the mean image quality scores for the median nerve (MN) and ulnar nerve (UN) were 3.71?±?0.46 and 3.23?±?0.67 for observer 1, and 3.70?±?0.46 and 3.22?±?0.71 for observer 2, respectively. The inter-observer agreement was excellent (k?=?0.843) and good (k?=?0.788), respectively. DW-MRN provided significantly improved visualisations of the second and the third common palmar digital nerves and three branches of UN compared with FS-PDWI (P?<?0.05). In patients, the mean image quality scores for the two observers were 3.24?±?0.62 and 3.10?±?0.83, inter-observer performance was excellent (k?=?0.842).

Conclusions

DW-MRN is feasible for improved visualisation of extremity nerves and their lesions in the wrist and palm with adequate image quality, thereby providing a supplementary method to conventional MR imaging.

Key points

? DW-MRN provides adequate image quality for wrist and palm neurography ? DW-MRN performs similarly to FS-PDWI in nerve visualisation at the wrist ? DW-MRN provides improved visualisation of small nerves in the palm ? DW-MRN serves as a supplementary method to evaluate peripheral neuropathies