The Significant Role of c-Abl Kinase in Barrier Altering Agonists-mediated Cytoskeletal Biomechanics.

Exploration of human pulmonary artery endothelial cell (EC) as a prototypical biomechanical system has important pathophysiologic relevance because this cell type plays a key role in the development of a wide variety of clinical conditions. The complex hierarchical organization ranging from the molecular scale up to the cellular level has an intimate and intricate relationship to the barrier function between lung tissue and blood. To understand the innate molecule-cell-tissue relationship across varied length-scales, the functional role of c-Abl kinase in the cytoskeletal nano-biomechanics of ECs in response to barrier-altering agonists was investigated using atomic force microscopy. Concurrently, the spatially specific arrangement of cytoskeleton structure and dynamic distribution of critical proteins were examined using scanning electron microscopy and immunofluorescence. Reduction in c-Abl expression by siRNA attenuates both thrombin- and sphingosine 1-phosphate (S1P)-mediated structural changes in ECs, specifically spatially-defined changes in elastic modulus and distribution of critical proteins. These results indicate that c-Abl kinase is an important determinant of cortical actin-based cytoskeletal rearrangement. Our findings directly bridge the gap between kinase activity, structural complexity, and functional connectivity across varied length-scales, and suggest that manipulation of c-Abl kinase activity may be a potential target for the treatment of pulmonary barrier disorders.

Imatinib Alters Agonists-mediated Cytoskeletal Biomechanics in Lung Endothelium.

The endothelium serves as a size-selective barrier and tightly controls the fluid exchange from the circulation to the surrounding tissues. In this study, a multiplexed microscopy characterization is developed to study the spatio-temporal effects of Abl kinases on endothelial cytoskeletal structure using AFM, SEM, and immunofluorescence. Sphingosine 1-phosphate (S1P) produces significant endothelial barrier enhancement by means of peripheral actin rearrangement. However, Abl kinase inhibition by imatinib reduces rapid redistribution of the important cytoskeletal proteins to the periphery and their association with the cortical actin ring. Herein, it moderates the thickness of the cortical actin ring, and diminishes the increase in elastic modulus at the periphery and cytoplasm. These findings demonstrate that imatinib attenuates multiple cytoskeletal changes associated with S1P-mediated endothelial barrier enhancement and suggest a novel role for Abl kinases in mediating these S1P effects. These observations bridge the gap between molecule dynamics, structure complexity and function connectivity across varied length-scales to improve our understanding on human pulmonary endothelial barrier regulation. Moreover, our study suggests a framework for understanding form-function relationships in other biomechanical subsystems, wherein complex hierarchical organization programmed from the molecular scale to the cellular and tissue levels has an intimate relationship to the overall physiological function.

Amphiphilic aminoclay-RGO hybrids: a simple strategy to disperse a high concentration of RGO in water.

The aqueous dispersion of graphene or reduced graphene oxide (RGO) is very much important to realize the full potential of these materials in many fields. Herein we present a simple route to prepare highly water dispersible aminoclay-RGO (AC-RGO) hybrids by the in situ condensation of aminoclay over graphene oxide (GO) followed by reduction with hydrazine hydrate. The resultant hybrids are stable in aqueous media even at concentrations up to 7.5 mg RGO per mL. To the best of our knowledge this is the highest concentration of an aqueous dispersion of RGO. Significantly, the hybrids are amphiphilic in nature and show simultaneous adsorption of Cytochrome C through hydrophobic interaction and DNA through electrostatic interaction. This strategy opens up new possibilities for the prospect of RGO in catalysis and biomedical applications.

Morphology control of nanostructures: Na-doped PbTe-PbS system.

The morphology of crystalline precipitates in a solid-state matrix is governed by complex but tractable energetic considerations driven largely by volume strain energy minimization and anisotropy of interfacial energies. Spherical precipitate morphologies are favored by isotropic systems, while anisotropic interfacial energies give energetic preference to certain crystallographically oriented interfaces, resulting in a faceted precipitate morphology. In conventional solid-solution precipitation, a precipitate's morphological evolution is mediated by surface anchoring of capping molecules, which dramatically alter the surface energy in an anisotropic manner, thereby providing exquisite morphology control during crystal growth. Herein, we present experimental evidence and theoretical validation for the role of a ternary element (Na) in controlling the morphology of nanoscale PbS crystals nucleating in a PbTe matrix, an important bulk thermoelectric system. The PbS nanostructures formed by phase separation from a PbI(2)-doped or undoped PbTe matrix have irregular morphologies. However, replacing the iodine dopant with Na (1-2 mol %) alters dramatically the morphology of the PbS precipitates. Segregation of Na at PbTe/PbS interfaces result in cuboidal and truncated cuboidal morphologies for PbS. Using analytical scanning/transmission electron microscopy and atom-probe tomography, we demonstrate unambiguously that Na partitions to the precipitates and segregates at the matrix/precipitate interfaces, inducing morphological anisotropy of PbS precipitates. First-principles and semiclassical calculations reveal that Na as a solute in PbTe has a higher energy than in PbS and that Na segregation at a (100) PbTe/PbS interface decreases the total energy of matrix/precipitate system, resulting in faceting of PbS precipitates. These results provide an impetus for a new strategy for controlling morphological evolution in matrix/precipitate systems, mediated by solute partitioning of ternary additions.

Anomalous electronic transport in dual-nanostructured lead telluride.

The Pb- and Sb- dual nanostructured PbTe system exhibits anomalous electronic transport behavior wherein the carrier mobility first increases and then decreases with increase in temperature. By combining in situ transmission electron microscopy observations and theoretical calculations based on energy filtering of charge carriers, we propose a plausible mechanism of charge transport based on interphase potential that is mediated by interdiffusion between coexisting Pb and Sb precipitates. These findings promise new strategies to enhance thermoelectric figure of merit via dual and multinanostructuring of miscible precipitates.

Direct evidence of oxidized gold on supported gold catalysts.

Supported gold catalysts have drawn worldwide interest due to the novel properties and potential applications in industries. However, the origin of the catalytic activity in gold nanoparticles is still not well understood. In this study, time-of-flight secondary ion mass spectroscopy (TOF-SIMS) has been applied to investigate the nature of gold in Au (1.3 wt %)/gamma-Al2O3 and Au (2.8 wt %)/TiO2 catalysts prepared by the deposition-precipitation method. The SIMS spectrum of the supported gold catalysts presented AuO-, AuO2-, and AuOH- ion clusters. These measurements show direct evidence for oxidized gold on supported gold catalysts and may be helpful to gaining better understanding of the origin of the catalytic activity.

A convenient and rapid sample repositioning approach for atomic force microscopy.

A novel repositioning approach is described for repeated observations of a specimen at a close proximal location in the atomic force microscope. The approach is similar to keystone architecture, whereby the repositioning is achieved by forming a male structured base for the specimen, and a corresponding female counterpart as the frame. For the combination of an acrylic acid frame and a metal base, 90% translation shifts are less than 10 microm, and almost all angular disorientations are within +3 degrees to -3 degrees . Nanometre-scale surface features can be relocated easily and reliably even after 40 imaging-removal-imaging cycles, dipping the specimen in solutions or heating up to 500 degrees C.

Indium-cadmium-oxide films having exceptional electrical conductivity and optical transparency: clues for optimizing transparent conductors.

Materials with high electrical conductivity and optical transparency are needed for future flat panel display, solar energy, and other opto-electronic technologies. In(x)Cd(1-x)O films having a simple cubic microstructure have been grown on amorphous glass substrates by a straightforward chemical vapor deposition process. The x = 0.05 film conductivity of 17,000 S/cm, carrier mobility of 70 cm2/Vs, and visible region optical transparency window considerably exceed the corresponding parameters for commercial indium-tin oxide. Ab initio electronic structure calculations reveal small conduction electron effective masses, a dramatic shift of the CdO band gap with doping, and a conduction band hybridization gap caused by extensive Cd 5s + In 5s mixing.

Investigation of antibiotic prophylaxis usage for vascular and nonvascular interventional procedures.

PURPOSE: To investigate current antibiotic prophylactic usage for arteriography, angioplasty, vascular stent placement, transjugular intrahepatic portosystemic shunt placement (TIPS), tunneled-port placement, inferior vena cava (IVC) filter placement, biliary drainage, genitourinary drainage, abdominal drainage, and enteral tube placement with an aim to better clarify indications and regimens for prophylaxis. METHODS: A questionnaire regarding antibiotic prophylactic usage was sent to 2,039 members of the Society of Cardiovascular and Interventional Radiology (SCVIR). There were 401 respondents. Replies were evaluated for frequency and indications of prophylaxis, specific prophylaxis used, and clarity of indications for prophylaxis. RESULTS: A majority of responders never used prophylaxis for arteriography, angioplasty, vascular stent placement, IVC filter placement, abdominal drainage, and enteral tube placement. Infective complication rates from nonusage ranged between 1% and 15%. Approximately 45% always used prophylaxis for tunneled-port placement and TIPS with a 13%-16% infective complication rate among nonusers. In contrast, a majority of responders always used prophylaxis for biliary and genitourinary drainage, with a 40%-58% infective complication rate in nonusers. More than 70% of responders believed that the indications for prophylaxis were not clear for arteriography, angioplasty, vascular stent placement, tunneled-port placement, TIPS, IVC filter placement, and enteral tube placement, and in contrast, that the indications for prophylaxis for biliary and genitourinary drainage were clear. Fifty-one percent of responders believed that indications for prophylaxis for abdominal drainage were clear. CONCLUSIONS: Indications for antibiotic prophylaxis are not clear to interventionalists for a large number of vascular and nonvascular interventional procedures. Prophylaxis appears unnecessary for routine arteriography, angioplasty, IVC filter placement, vascular stent placement, or enterostomy tube placement. Antibiotic prophylaxis is warranted for TIPS and tunneled-port placement. Conversely, indications for antibiotic prophylaxis are clear to interventionalists for biliary and genitourinary drainage procedures. Routine prophylaxis remains warranted for both.

Value of radiography in diagnosing complications of cardioverter defibrillators implanted without thoracotomy in 437 patients.

OBJECTIVE: This study evaluated the usefulness of radiography in assessing the frequency and cause of complications of nonthoracotomy-implanted cardioverter defibrillators. MATERIALS AND METHODS: Between May 1992 and December 1995, 437 consecutive patients at our institution underwent cardioverter defibrillator placement. Routine follow-up included external device testing at 6 weeks after placement and every 3 months thereafter. Chest radiographs were obtained immediately after placement, annually, and at the time of any suspected complication. Retrospective review of radiographs and medical charts was done for all patients with clinical complications. RESULTS: Forty-five complications (10%) were clinically diagnosed: lead or patch fracture in fifteen (33%) patients, electric lead dysfunction in eight (18%), infection in eight (18%), lead retraction in six (13%), patch fold in two (5%), hematoma in two (5%), and other complications in four (9%) patients. Eighteen complications (40%) were radiographically evident. Lead retraction, hematoma, patch fold, patch migration, and the twiddler syndrome were radiographically confirmed in 100% of cases. The average time for these complications to be detected was 68 days; 92% were detected within 23 days. Conversely, only four (27%) lead fractures, one (13%) electric lead dysfunction, and one (13%) infection were radiographically confirmed. These latter complications were discovered an average of 579 days after cardioverter defibrillator placement. CONCLUSION: Radiography plays a secondary role in the diagnosis of cardioverter defibrillator complications and is particularly limited beyond 1 month after placement. Radiographs may be helpful in the first month after placement because early complications are the most radiographically apparent.

Transmission EELS of oxide superconductors with a cold field emission TEM.

Electron energy loss spectrometry (EELS) with a cold field emission gun (cFEG) transmission electron microscope (TEM) is implemented to analyze the evolution of the electronic structure and dielectric function of oxide superconductors. The O-K core loss spectra of p-type doped oxide superconductors are analyzed in terms of holes formation on oxygen sites, while low loss spectra are analyzed for free carrier plasmas, other spectral excitations, and their crystallographic confinement. It is illustrated that the transmission EELS with a cFEG TEM very much complement soft X-ray absorption spectroscopy and optical spectroscopy, with the added advantages of high spatial resolution (approximately 1-100 nm), and is compatible with other analytical, diffraction, and imaging techniques, which are readily available in a cFEG TEM.

Persistent iliac endarteritis with pseudoaneurysm formation following balloon-expandable stent placement.

We present a patient who developed endarteritis and pseudoaneurysm formation complicating iliac artery stent placement. Blood cultures grew Staphylococcus aureus. Three weeks after antibiotic treatment, the aortic bifurcation and the stents were removed, together with the left common iliac artery pseudoaneurysm. As with any other implantable device, septic complications are dreaded and should be recognized and treated early. Consideration may be given to the use of appropriate prophylactic antibiotics.

MR portography: preliminary comparison with CT portography and conventional MR imaging.

Magnetic resonance (MR) imaging with arterial portography (MRAP) was compared with computed tomography with arterial portography (CTAP) and conventional MR imaging for preoperative evaluation of hepatic masses in eight patients (nine studies). Twenty contiguous, 10-mm-thick-section CTAP images were obtained. MR imaging included T1- and T2-weighted spin-echo and fast multiplanar SPGR (spoiled gradient-recalled acquisition in the steady state) techniques. For MRAP, 0.1 mmol/kg gadopentetate dimeglumine was injected into the superior mesenteric artery. Portographic-phase, 8-mm-thick-section, axial SPGR images were first obtained, followed by "systemic phase" SPGR images. Lesions were seen best on the portographic-phase MRAP images and were less conspicuous on the systemic-phase MRAP, CTAP and conventional MR images. Of 19 visualized lesions, 18 were seen with MRAP; however; five subcentimeter lesions seen with MRAP were not seen with conventional MR imaging or CTAP. Systemic recirculation of iodinated contrast material from the bolus and from previous angiography is a potential limitation of CTAP. For both CTAP and MRAP, optimal results are expected if all images are obtained during a single breath hold, within seconds of the onset of contrast agent administration.

Direct Determination of Grain Boundary Atomic Structure in SrTiO3.

An atomic structure model for a 25 degrees [001] symmetric tilt grain boundary in SrTiO(3) has been determined directly from experimental data with the use of high-resolution Z-contrast imaging coupled with electron energy loss spectroscopy. The derived model of the grain boundary was refined by bond-valence sum calculations and reveals candidate sites for dopant atoms in the boundary plane. These results show how the combined techniques can be used to deduce the atomic structure of defects and interfaces without recourse to preconceived structural models or image simulations.

Gastric stump lymphoma.

Lymphoma occurring in the post-operative stomach would appear to be very rare with only five previously recorded cases. In three of these, focal lymphoid hyperplasia or pseudolymphoma had been found at the time of the original ulcer surgery, or at subsequent biopsies of the gastric stump or anastomotic sites. These latter three cases developed lymphoma within 11 years of the ulcer surgery as against the 20 years or longer generally found in cases of gastric stump carcinoma. Two cases presenting with gastric stump lymphoma approximately 20 years after Billroth 2 partial gastrectomy are reported. In neither of these two cases, nor in the other two patients previously recorded with post-operative gastric lymphoma 20 or more years following gastric surgery, was luminal focal lymphoid hyperplasia reported at the time of the original gastric surgery. It is postulated that these two small groups may have developed lymphoma due to differing malignant stimuli.

Arterial abnormalities following orthotopic liver transplantation: arteriographic findings and correlation with Doppler sonographic findings.

OBJECTIVE: We studied the findings on conventional arteriography in patients who had suspected graft ischemia after orthotopic liver transplantation to determine the value of a single Doppler signal in predicting these lesions. MATERIALS AND METHODS: We retrospectively reviewed selective visceral arteriograms with abnormal findings from 20 adults who had suspected graft ischemia after orthotopic liver transplantation and a single Doppler signal from the hepatic artery at the porta hepatis on sonograms obtained before arteriography. Arteriographic abnormalities were categorized according to morphology and location as follows: stenosis of recipient's hepatic artery, occlusion or stenosis of the transplanted extrahepatic artery, and occlusion or stenosis of the transplanted intrahepatic artery. RESULTS: Twenty-three arteriographic abnormalities were detected: four recipient celiac axis stenoses, seven extrahepatic occlusions, nine extrahepatic stenoses, and two occlusions and one stenosis of the transplanted intrahepatic artery. Six of the extrahepatic occlusions, two of the extrahepatic stenoses, and none of the recipient artery stenoses or the intrahepatic occlusions or stenoses were correctly diagnosed on the basis of Doppler findings. One patient with both an extrahepatic stenosis and an extrahepatic occlusion was thought to have an intrahepatic occlusion, and two patients with mild (< 50%) extrahepatic stenoses and one with an intrahepatic occlusion were thought to have an extrahepatic occlusion. CONCLUSION: A wide spectrum of abnormalities in the recipient's celiac axis or the transplanted arteries that may be associated with graft ischemia after orthotopic liver transplantation are often not detected or findings are misinterpreted on routine Doppler examination. In patients with suspected graft ischemia, visceral arteriography should be performed promptly to confirm the diagnosis and to allow early intervention.

Role of selective arteriography in the diagnosis of a ruptured middle colic artery aneurysm.

A case of a ruptured middle colic artery is reported. The diagnosis was initially overlooked and eventually made by selective arteriography. Aneurysms of visceral arteries are rare and rupture of them even more infrequent. Awareness of this potentially fatal and treatable entity should enable early detection by selective visceral arteriography. The roles of embolization and surgery in the management of visceral aneurysms are discussed.

Buckytubes and derivatives: their growth and implications for buckyball formation.

Transmission electron microscopy (TEM) observations of graphite tubules (buckytubes) and their derivatives have revealed not only the previously reported buckytube geometries but also additional shapes of the buckytube derivatives. Detailed cross-sectional TEM images reveal the cylindrical cross section of buckytubes and the growth pattern of buckytubes as well as their derivatives. These observations of frozen growth stages of buckytubes and derivatives suggest a helical growth mechanism analogous to that of crystal growth via screw dislocations. The helicacy of buckytubes is analyzed by electron diffraction whereas the anisotropy of electronic structure is revealed by momentum transfer resolved electron energy loss spectrometry. Based on the TEM observations, it is proposed that buckytubes act as precursors to closed-shell fullerene (buckyball) formation and the possible steps in buckyball formation are outlined. In arc evaporation experiments in which residue rods (containing various amounts of buckytubes) were used as the starting anode for fullerene production, the amount of buckytubes in the rod was correlated with fullerene yield.