The Materials Science beamline upgrade at the Swiss Light Source.

The Materials Science beamline at the Swiss Light Source has been operational since 2001. In late 2010, the original wiggler source was replaced with a novel insertion device, which allows unprecedented access to high photon energies from an undulator installed in a medium-energy storage ring. In order to best exploit the increased brilliance of this new source, the entire front-end and optics had to be redesigned. In this work, the upgrade of the beamline is described in detail. The tone is didactic, from which it is hoped the reader can adapt the concepts and ideas to his or her needs.

Intraductal papillary mucinous neoplasm of the pancreas associated with neuroendocrine tumor: A case report.

INTRODUCTION: Intraductal papillary mucinous neoplasm is an uncommon cystic tumor of pancreas that can be associated with ductal adenocarcinoma. Coexistence of pancreatic IPMN and neuroendocrine tumor is very rare. Here, we report the imaging features of mixed type intraductal papillary mucinous neoplasia of the pancreas with high grade dysplasia together with neuroendocrine carcinoma and perform review of the literature. PRESENTATION: A 68-year old patient has been evaluated for possible IPMN that was suspected during ultrasound. MRI revealed main and side branch duct dilatations. At the head, a contrast enhancing nodular lesion was identified. Due to the presence of high risk stigmata according to guidelines, surgery was performed. Histopathological examination revealed an unusual association, including mixed type IPMN and neuroendocrine carcinoma. DISCUSSION: The concomitant occurrence of pancreatic IPMN and neuroendocrine tumor has been reported in case studies and brief reviews. Yet, the imaging findings and underlying molecular mechanisms of this entity has not been fully understood. In addition to this unusual association, pancreatic intraepithelial neoplasia was also detected in the present case. Although majority of neuroendocrine tumor associated IPMNs were reported to be having low grade dysplasia, our patient had high grade dysplasia. Further studies and reviews with larger groups are needed to establish imaging features and underlying molecular mechanisms of this rare association. CONCLUSION: Although the major concern during work-up of IPMN is presence of associated pancreatic ductal adenocarcinoma, the possibility of neuroendocrine tumor, in the presence of a hypervascular solid foci on imaging studies should be kept in mind.

An unusual cause of pelvic hemorrhage: multidetector CT diagnosis of inferior mesenteric vein injury.

Pelvic trauma can lead to uncontrollable bleeding and even death. Although significantly decreased with the application of novel treament modalities and the use of state-of-the-art imaging equipment, pelvic trauma and subsequent bleeding remains to stay as a major source of morbidity and mortality. In this case we present a patient suffering from pelvic bleeding from the inferior mesenteric vein due to sigmoid mesocolon injury. Similar finding has not been reported as an isolated source of pelvic hemorrhage. We also propose that the routine use of reformatted images obtained with multidetector CT scanners in patients with hemoperitoneum may be a highly useful adjunct for the correct identification of the source of hemorrhage.

Unusual presentation of prostate cancer with generalized lymphadenopathy and unilateral leg edema.

Prostate cancer most often metastases to bones and regional lymph nodes. Disseminated metastasis to distant lymph nodes is very rare. We report a case presenting with generalized lymphadenopathy and related left leg edema without any urinary symptoms and finally diagnosed as prostate cancer.

PolLux: a new facility for soft x-ray spectromicroscopy at the Swiss Light Source.

We report on the successful installation and operation of a scanning transmission x-ray microspectroscope (STXM) at the PolLux facility at the Swiss Light Source. This integration of an advanced STXM with improved sample handling capabilities and a novel beamline provides unique capabilities. PolLux uses linearly or circularly polarized x-rays from a bending magnet with an extended photon energy range (200-1400 eV). It is therefore well suited to determine a sample's quantitative chemical composition, molecular orientation, or thickness of organic as well as condensed matter materials. The local magnetic state of magnetic thin films is accessible through fast helicity switching by steering the electron beam off axis through the bending magnet. Ex vacuo girder movers allow fast and highly reproducible (<1 microm) alignment of the instrument with respect to the photon beam. The present spatial resolution is approximately 20 nm, limited by the zone plates utilized. The instrument has the stability and positional resolution to operate with much higher resolution optics as it becomes available. In addition to characterization experiments, we present several typical examples from materials research and environmental science to exemplify the capabilities.

A membrane-proximal tyrosine-based signal mediates internalization of the HIV-1 envelope glycoprotein via interaction with the AP-2 clathrin adaptor.

The envelope glycoprotein (Env) of human immunodeficiency virus, type 1 (HIV-1) undergoes rapid internalization after its transport to the cell surface. Env internalization is dependent upon information contained within the cytosolic domain of the protein. Here, we report that the cytosolic domain of Env binds specifically to the medium chain, mu 2, of the clathrin-associated protein complex AP-2, as well as to the complete AP-2 complex. The Env cytosolic domain contains two highly conserved tyrosine-based motifs (Y712SPL and Y768HRL), both of which are capable of binding to mu 2 when presented as short peptides. However, only the membrane-proximal motif Y712SPL binds to mu 2 and is required for internalization in the context of the whole cytosolic domain of Env. A glycine residue (Gly711) adjacent to the Y712SPL motif is also important for binding to mu 2/AP-2 and internalization. These observations suggest that the accessibility of the membrane-proximal GY712SPL to mu 2/AP-2 determines its function as a signal for recruitment of HIV-1 Env into clathrin-coated pits and its ensuing internalization.

The highly conserved C-terminal dileucine motif in the cytosolic domain of the human immunodeficiency virus type 1 envelope glycoprotein is critical for its association with the AP-1 clathrin adaptor [correction of adapter].

Short amino acid sequences in the cytosolic domains of transmembrane proteins are recognized by specialized adaptor [corrected] proteins which are part of coated vesicles utilized to transport membrane proteins between the trans-Golgi network (TGN) and the plasma membrane (forward and backward). Previously, we and others reported that the membrane-proximal tyrosine residues Y712 (human immunodeficiency virus [HIV]) and Y721 (simian immunodeficiency virus [SIV]) in the envelope glycoprotein (Env) of the primate lentiviruses are crucial for the association of Env with clathrin-associated adaptor [corrected] complex AP-2. The same tyrosine-based endocytosis motifs in the cytosolic domains (EnvCD) of transmembrane gp41 of HIV type 1 (HIV-1) and SIV, respectively, were also shown to modulate the interaction with TGN- and endosome-based clathrin-associated complex AP-1. Our findings suggested that EnvCD binding to AP-1, unlike the association of EnvCD with AP-2, is dependent largely on residues other than Y712 and Y721. Here, we tested if motifs downstream of Y712 affect HIV-1 EnvCD-AP-1 binding and Env trafficking. Mutational analysis revealed that the C-terminal leucine-based motif in Env was crucial for the recruitment of AP-1 in vitro and in Env-expressing cells. In addition to affecting Env-AP-1 association, mutations at the C terminus of Env also altered the subcellular localization of Env, suggesting that proper post-Golgi routing of Env depends on its recruitment of AP-1. Finally, the C-terminal dileucine was shown to assist the membrane-proximal Y712 motif in restricting the cell surface expression of Env.