Agrin plays an organizing role in the formation of sympathetic synapses

Agrin is a nerve-derived factor that directs neuromuscular synapse formation, however its role in regulating interneuronal synaptogenesis is less clear. Here, we examine agrin's role in synapse formation between cholinergic preganglionic axons and sympathetic neurons in the superior cervical ganglion (SCG) using agrin-deficient mice. In dissociated cultures of SCG neurons, we found a significant decrease in the number of synapses with aggregates of presynaptic synaptophysin and postsynaptic neuronal acetylcholine receptor among agrin-deficient neurons as compared to wild-type neurons. Moreover, the levels of pre- and postsynaptic markers at the residual synapses in agrin-deficient SCG cultures were also reduced, and these defects were rescued by adding recombinant neural agrin to the cultures. Similarly, we observed a decreased matching of pre- and postsynaptic markers in SCG of agrin-deficient embryos, reflecting a decrease in the number of differentiated synapses in vivo. Finally, in electrophysiological experiments, we found that paired-pulse depression was more pronounced and posttetanic potentiation was significantly greater in agrin-deficient ganglia, indicating that synaptic transmission is also defective. Together, these findings indicate that neural agrin plays an organizing role in the formation and/or differentiation of interneuronal, cholinergic synapses

Detection of heart transplant rejection using Raman spectroscopy

Poster presented at Biomedical Technology Showcase 2006, Philadelphia, PA. Retrieved 18 Aug 2006 from http://www.biomed.drexel.edu/new04/Content/Biomed_Tech_Showcase/Poster_Presentations/Chang.pdf.Acute cardiac rejection by internal immune system is the major limitation to the successful heart transplantation. As a current gold standard, an endomyocardial biopsy from a transplanted heart is taken and the degree of cardiac rejection is determined pathologically under a microscope after H&E staining. The goal of our research is to ultimately replace this biopsy procedure with optical diagnostic, namely Raman spectroscopy. Here we have successfully demonstrated Raman spectroscopy’s ability to distinguish between Grade-0 and Grade-2 heart transplant rejections. According to 2004 ISHLT (International Society for Heart and Lung Transplantation) cardiac rejection grading system, significant myocyte damage is identified in biopsies from Grade-2 and above. Raman spectroscopy, i.e. optical diagnostic without physically removing the heart tissues with biopsy, could therefore be potentially beneficial for patients with higher grade cardiac rejections as they require more frequent surveillance biopsies that have been shown to increase the mortality rate

The effect of stress on nuclear protein transport : classical nuclear protein transport versus the nuclear transport of heat shock proteins

The stress response is conserved among eukaryotes and affects different cellular functions including protein transport. Here, we have investigated the effect of different types of stress on classical nuclear protein import as well as nuclear import of Ssa4p family of heat shock proteins in Saccharomyces cerevisiae.Under normal conditions, Aequorea victoria green fluorescent protein (GFP), carrying a classical nuclear localization sequence (cNLS-GFP) is nuclear. However, cNLS-GFP equilibrates throughout the cell upon exposure to heat, ethanol, H2O2 or starvation. Redistribution of the small GTPase Gsp1p, a soluble nuclear transport factor, correlates with cNLS-GFP equilibration. This suggests that a collapse of the Gsp1p gradient underlies the inhibition of classical nuclear protein import. In contrast to cNLS-GFP, the cytoplasmic heat shock protein Ssa4p accumulates in nuclei when classical nuclear import is inhibited. The N-terminal 236 amino acid residues of Ssa4p are sufficient for nuclear localization of Ssa4p-GFP upon heat and ethanol stress. The nuclear localization of Ssa4p(1--236)-GFP requires components of Gsp1-GTPase system, but is independent of Srp1p, the cNLS receptor.Ssa4p(16--642)-GFP accumulates in nuclei of starving cells, mediated by a hydrophobic stretch of amino acid residues in its N-terminal domain. This nuclear localization is reversible upon addition of fresh medium and its export is sensitive to oxidants and temperature-dependent

Training minimal invasive approaches in hepatopancreatobilliary fellowship: the current status

AbstractBackgroundThere has been an increasing role of advanced minimally invasive procedures in hepatopancreatobilliary (HPB) surgery. However, there are no set minimum laparoscopic case requirements.MethodsA 14-question electronic survey was sent to 82 worldwide HPB fellowship programme directors.ResultsForty-nine per cent (n=40) of the programme directors responded. The programmes were predominantly university based (83%). Programmes had either one (55%) or two fellows (40%) each year. Programmes (35–48%) had average annual volumes of 51–100 hepatic, 51–100 pancreatic and 25–50 biliary cases. For many programmes, <10% of hepatic (48%), pancreatic (40%) and biliary (70%) cases were done laparoscopically. The average annual fellow case volumes for hepatic, pancreatic and biliary surgeries were 25–50 (62%), 25–50 (47%) and <25 (50%), respectively. The average annual number of hepatic, pancreatic and biliary cases done laparoscopically by a fellow was 9, 9 and 4, which constitutes 36%, 36% and 16%, respectively, of the International Hepato-Pancreato-Billiary Association (IHPBA) requirement.ConclusionWe surmise that the low average number of surgeries performed by minimally-invasive techniques by HPB fellows is not sufficient in today's practice. Should there be an increase in the minimal number of hepatic, pancreatic and complex biliary cases to 50, 50, and 25, with at least 50% of these performed laparoscopically

Nodal sampling in pancreaticoduodenectomy: does it change our management?1

Background. Lymph node involvement in periampullary malignancy is the single most important factor in predicting survival in pancreaticoduodenectomy (PD). The role of nodal sampling in PD has not been well evaluated. This study evaluates the utility of nodal sampling of nodal stations 8 and 12, which are easily dissected early in PD, in overall final nodal status. Patients and methods. Fifty patients underwent PD at a single institution by a one surgeon over a 15 month period. Nodal stations 8 and 12 were sent separately for pathologic evaluation. Twenty-eight patients had a final diagnosis of periampullary malignancy. Demographic and pathologic data were collected retrospectively from patient charts. Positive and negative predictive values of nodes 8 and 12 were evaluated. Results. Eighteen of 28 patients with a diagnosis of periampullary malignancy had pathologically negative nodes 8 and 12, and a final nodal status (all peripancreatic lymph nodes) negative for nodal involvement. Nine of 28 patients had a negative nodal sampling result, but a positive final nodal status for metastatic tumor. The remaining four patients had both positive nodal sampling and final nodal status for metastatic tumor. The negative predictive value of negative nodes 8 and 12 was 0.625. Conclusion. The negative predictive of a negative node 8 and 12 of 0.625 suggests that the decision to proceed with or abort PD should not be based on intraoperative evaluation of these nodes. Performance of PD should be undertaken if technically feasible, and not based on intraoperative nodal assessment

Evaluation of Hepato-Pancreato-Biliary (HPB) fellowships: an international survey of programme directors

OBJECTIVES: This report describes a survey undertaken with the aim of assessing the current status of available fellowships in hepatopancreatobiliary (HPB) surgery in order to identify steps to be taken to ensure the provision of successful training in this specialty. METHODS: An online survey was conducted among members of the International Hepato-Pancreato-Biliary Association (IHPBA) targeting registered and non-registered HPB surgery fellowships. A total of 71 programmes are registered on the IHPBA website and 40 fellowship directors completed the survey. Only 18 completed surveys referred to programmes previously listed on the website. RESULTS: Responses showed great diversity among centres regarding their requirements for application, the duration of training and exposure to HPB cases during the fellowship. Factors associated with higher levels of training included the country of fellowship, a third year of training and the presence of a well-structured HPB curriculum. Over 90% of responders seek official accreditation from their regional association (i.e. the European, American and Asian-Pacific HPB Associations). Most programmes would welcome official IHPBA or regional association monitoring of their fellowship. CONCLUSIONS: This survey discloses important information which will allow the IHPBA Education and Training Committee to move forward. The next steps should include close monitoring of the performance of fellows by creating a fellows' registry, as well as a blog or forum which can be used to further enhance communication among fellows. The availability of registration to both programme directors and fellows may eventually lead to an official fellowship accreditation process. © 2011 International Hepato-Pancreato-Biliary Association