Direct Visualization (direct + visualization)

Distribution by Scientific Domains
Distribution within Medical Sciences


Selected Abstracts


Direct Visualization of Deformation in Volumes

COMPUTER GRAPHICS FORUM, Issue 3 2009
Stef Busking
Abstract Deformation is a topic of interest in many disciplines. In particular in medical research, deformations of surfaces and even entire volumetric structures are of interest. Clear visualization of such deformations can lead to important insight into growth processes and progression of disease. We present new techniques for direct focus+context visualization of deformation fields representing transformations between pairs of volumetric datasets. Typically, such fields are computed by performing a non-rigid registration between two data volumes. Our visualization is based on direct volume rendering and uses the GPU to compute and interactively visualize features of these deformation fields in real-time. We integrate visualization of the deformation field with visualization of the scalar volume affected by the deformations. Furthermore, we present a novel use of texturing in volume rendered visualizations to show additional properties of the vector field on surfaces in the volume. [source]


Direct Visualization of Abasic Sites on a Single DNA Molecule Using Fluorescence Microscopy,

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2002
Tamaki Hirose
ABSTRACT A new method was developed to allow direct visualization of damaged sites on individual DNA molecules. Fluorescence in situ hybridization on extended DNA molecules was modified to detect a single abasic site. Abasic sites were specifically labeled with a biotinylated aldehyde-reactive probe and fluorochrome-conjugated streptavidin. The light emitted by a single fluorochrome,DNA complex was calibrated. The number of abasic sites on the DNA molecule was estimated by counting each fluorochrome,DNA complex. The present study directly visualized and characterized the abasic sites of single DNA molecules. [source]


Direct Visualization of Disulfide Bonds through Diselenide Proxies Using 77Se NMR Spectroscopy,

ANGEWANDTE CHEMIE, Issue 49 2009
Mehdi Mobli Dr.
Selen als Sehhilfe: Viele Proteine enthalten verbrückende Disulfidbindungen, die häufig eine wesentliche Rolle für Proteinstruktur, -faltung und -funktion spielen. Doch die Methoden, um die Verknüpfungsmuster von Disulfidbindungen in Proteinen zu bestimmen, sind technisch schwierig und führen leicht zu Fehlinterpretationen. Nun ist es möglich, diese Verknüpfungen in nativen Proteinen direkt mithilfe der 77Se-NMR-Spektroskopie zu visualisieren. [source]


In-vivo visualization of phagocytotic cells in rat brains after transient ischemia by USPIO

NMR IN BIOMEDICINE, Issue 4 2002
M. Rausch
Abstract Cerebral ischemia provokes tissue damage by two major patho-physiological mechanisms. Direct cell necrosis is induced by diminished access of neurons and glia to essential nutrients such as glucose and oxygen leading to energy failure. A second factor of cellular loss is related to the activation of immune-competent cells within and around the primary infarct. While granulocytes and presumably monocytes are linked to the no-reflow phenomenon, activated microglia cells and monocytes can release cytotoxic substrates, which cause delayed cell death. As a consequence the infarct volume will increase, despite restoration of cerebral perfusion. In the past, visualization of immune competent cells was only possible by histological analysis of post-mortem tissue. However, contrast agents based on small particles of iron oxide are known to accumulate in organs rich in cells with phagocytotic function. These particles can be tracked in vivo by MRI methods based on their relaxation properties. In the present study, the spatio-temporal distribution of USPIO particles was monitored in a rat model of transient cerebral infarction using T1 - and T2 -weighted MRI sequences. USPIO were detected in vessels at 24,h after administration. At later time points specific accumulation of USPIO was observed within the infarcted hemisphere, with maximal signal enhancement on day 2. Their detectability based on T1 -contrast disappeared between day 4 and day 7. Immuno-histochemically (IHC) stains confirmed the presence of macrophages, presumably blood-derived monocytes within areas of T1 signal enhancement. Direct visualization of iron-burdened macrophages by IHC was only possible later than day 3 after occlusion. Copyright © 2002 John Wiley & Sons, Ltd. [source]


The Effect of Ablation Electrode Length and Catheter Tip to Endocardial Orientation on Radiofrequency Lesion Size in the Canine Right Atrium

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1 2002
RODRIGO C. CHAN
CHAN, R.C., et al.: The Effect of Ablation Electrode Length and Catheter Tip to Endocardial Orientation on Radiofrequency Lesion Size in the Canine Right Atrium. Although the determinants of radiofrequency lesion size have been characterized in vitro and in ventricular tissue in situ, the effects of catheter tip length and endocardial surface orientation on lesion generation in atrial tissue have not been studied. Therefore, the dimensions of radiofrequency lesions produced with 4-, 6-, 8-, 10-, and 12-mm distal electrode lengths were characterized in 26 closed-chested dogs. The impact of parallel versus perpendicular catheter tip/endocardial surface orientation, established by biplane fluoroscopy and/or intracardiac echocardiography, on lesion dimensions was also assessed. Radiofrequency voltage was titrated to maintain a steady catheter tip temperature of 75°C for 60 seconds. With a perpendicular catheter tip/tissue orientation, the lesion area increased from 29 ± 7 mm2 with a 4-mm tip to 42 ± 12 mm2 with the 10-mm tip, but decreased to 29 ± 8 mm2 with ablation via a 12-mm tip. With a parallel distal tip/endocardial surface orientation, lesion areas were significantly greater: 54 ± 22 mm2 with a 4-mm tip, 96 ± 28 mm2 with a 10- mm tip and 68 ± 24 mm2 with a 12-mm tip (all P < 0.001 vs perpendicular orientation). Lesion lengths and apparent volumes were larger with parallel, compared to perpendicular tip/tissue orientations, although lesion depth was independent of catheter tip length with both catheter tip/tissue orientations. Electrode edge effects were not observed with any tip length. Direct visualization using intracardiac ultrasound guidance was subjectively helpful in insuring an appropriate catheter tip/tissue interface needed to maximize lesion size. Although atrial lesion size is critically dependent on catheter tip length, it is more influenced by the catheter orientation to the endocardial surface. This information may also be helpful in designing electrode arrays for the creation of continuous linear lesions for the elimination of complex atrial tachyarrhythmias. [source]


Cellular sources, targets and actions of constitutive nitric oxide in the magnocellular neurosecretory system of the rat

THE JOURNAL OF PHYSIOLOGY, Issue 3 2005
Javier E. Stern
Nitric oxide (NO) is a key activity-dependent modulator of the magnocellular neurosecretory system (MNS) during conditions of high hormonal demand. In addition, recent studies support the presence of a functional consitutive NO tone. The aim of this study was to identify the cellular sources, targets, signalling mechanisms and functional relevance of constitutive NO production within the supraoptic nucleus (SON). Direct visualization of intracellular NO, along with neuronal nitric oxide synthase (nNOS) and cGMP immunohistochemisty, was used to study the cellular sources and targets of NO within the SON, respectively. Our results support the presence of a strong NO basal tone within the SON, and indicate that vasopressin (VP) neurones constitute the major neuronal source and target of basal NO. NO induced-fluorescence and cGMP immunoreactivity (cGMPir) were also found in the glia and microvasculature of the SON, suggesting that they contribute as sources/targets of NO within the SON. cGMPir was also found in association with glutamic acid decarboxylase 67 (GAD67)- and vesicular glutamate transporter 2 (VGLUT2)-positive terminals. Glutamate, acting on NMDA and possibly AMPA receptors, was found to be an important neurotransmitter driving basal NO production within the SON. Finally, electrophysiological recordings obtained from SON neurones in a slice preparation indicated that constitutive NO efficiently restrains ongoing firing activity of these neurones. Furthermore, phasically active (putative VP) and continuously firing neurones appeared to be influenced by NO originating from different sources. The potential roles for basal NO as an autocrine signalling molecule, and one that bridges neuronal,glial,vascular interactions within the MNS are discussed. [source]


Donor Harvesting: A New Approach to Minimize Transection of Hair Follicles

DERMATOLOGIC SURGERY, Issue 4 2000
Damkerng Pathomvanich MD
Background. There are several methods for harvesting donor hairs, including punch excision, single-bladed knife excision, and multibladed knife excision. All of these procedures are blind and thus result in transection of hair follicles. Transection of hair follicles during harvesting results in fewer follicles being available for transplantation, detrimentally affecting the final cosmetic result. Objective. To explore a new method of donor hair harvesting called "donor dissecting." This new procedure is an open technique because hair follicles are directly visualized during the harvesting process. Methods. The technique of donor dissecting utilizes a #15 scalpel blade to excise the donor hair ellipse from the occiput while maintaining meticulous hemostasis. This enables individual hair follicles to be visualized and protected from transection during the harvesting process. Once the donor ellipse is harvested, it is then further divided into individual mini- and micrografts using direct visualization of individual follicles to again prevent transection. Results. The technique of donor dissecting was utilized in 50 consecutive hair transplant patients. Utilizing this new technique, only 1.9% of hair follicles in the donor ellipse were transected during the harvesting process. The dissection of the donor ellipse 1.2% follicles being transected in the graft cutting process. Combining the donor dissection technique with dissection of the individual grafts, we were able to transect 1.59% of hair follicles harvested for transplantation. Conclusion. The technique of donor dissection minimizes the transection of hair follicles in the donor hair harvesting phase of hair transplantation. This technique is superior to the blind methods of donor harvesting which have been plagued by the problem of hair follicle transection. [source]


WHAT KIND OF BENEFIT DO WE EXPECT FOR PERORAL PANCREATOSCOPY IN THE DIAGNOSIS OF INTRADUCTAL PAPILLARY MUCINOUS TUMOR OF THE PANCREAS?

DIGESTIVE ENDOSCOPY, Issue 2006
Taketo Yamaguchi
Intraductal papillary mucinous tumor (IPMT) of the pancreas is characterized by slow growth and a relatively favorable prognosis, however, invasive cancer originating in an IPMT is associated with a poor prognosis. Although various parameters in imaging modalities have been advocated to differentiate between benign IPMN and malignant ones, it is not easy to obtain definite diagnosis based on these parameters. Peroral pancreatoscopy (POPS) allows a clear and direct visualization of the pancreatic duct, providing useful information regarding tumor nature in IPMT. The authors have studied the usefulness of POPS in the diagnosis of IPMT. Nevertheless, its usefulness is not necessarily widely accepted and the significance of POPS is still controversial. In this review, the authors intended to address the diagnostic value of POPS and to clarify its role in the diagnosis of IPMT. The authors think treatment of IPMT can be improved by introducing POPS because the determination of surgical procedure as well as the area of resection based on the preoperative diagnosis of the involvement of the main pancreatic duct and branch duct is inevitable. [source]


The Use of 3D Contrast-Enhanced CT Reconstructions to Project Images of Vascular Rings and Coarctation of the Aorta

ECHOCARDIOGRAPHY, Issue 1 2009
Thomas G. Di Sessa M.D.
Background: Aortic arch and pulmonary artery anomalies make up a group of vascular structures that have complex three-dimensional (3D) shapes. Tortuosity as well as hypoplasia or atresia of segments of the aortic arch or pulmonary artery makes the conventional two-dimensional (2D) imaging difficult. Methods: Nine patients with native coarctation or recoarctation and 4 patients with a vascular ring had a CT scan as a part of their clinical evaluation. There were 7 males. The mean age was 11.7 years. (range 19 days to 29 years) The mean weight was 22.7 kg (range 3.3,139.0 kg). The dicom data from contrast CT scans were converted by the Amira software package into a 3D image. The areas of interest were selected. The images were then projected in 3D on a standard video monitor and could be rotated 360° in any dimension. Results: Adequate CT scans and 3D reconstructions were obtained in 12 of 13 patients. There were 85,1,044 slices obtained in the adequate studies. We could not reconstruct a 3D image from a patient's CT scan that had only 22 slices. The anatomy defined by 3D was compared to 2D CT imaging and confirmed by cardiac catheterization or direct visualization in the operating room in the 12 patients with adequate 3D reconstructions. In 5 of 12 patients, 3D reconstructions provided valuable spatial information not observed in the conventional 2D scans. Conclusion: We believe that 3D reconstruction of contrast-enhanced CT scans of these complex structures provides additional valuable information that is helpful in the decision-making process. [source]


Triage Patients with Suspected Pulmonary Embolism in the Emergency Department Using a Portable Ultrasound Device

ECHOCARDIOGRAPHY, Issue 5 2008
Nicolas Mansencal M.D.
The diagnosis of pulmonary embolism (PE) is difficult, despite validated diagnostic models. We sought to determine the value of a portable ultrasound device for triage of patients with suspected PE referred to the emergency department, using simplified echo criteria. We prospectively studied 103 consecutive patients with suspected PE, referred to our emergency department. After D-dimer screening, 76 patients were prospectively enrolled in this ultrasound study and underwent helical chest tomography, transthoracic echocardiography, and venous ultrasonography. Among patients with PE (n = 31), a right ventricular dilation was detected in 17 patients (55%), a direct visualization of clot in the lower limbs was present in 18 patients (58%), and 8 patients (26%) had both right ventricular dilation and deep venous thrombosis. The sensitivity and specificity of a combined ultrasound strategy using echocardiography and venous ultrasonography were respectively 87% (95% confidence interval 74% to 96%), and 69% (95% confidence interval 53% to 82%). The sensitivity of this combined strategy was significantly improved as compared to venous ultrasonography alone (P = 0.01) or echocardiography alone (P = 0.005). In patients with dyspnea or with high clinical probability of PE, this combined strategy was particularly relevant with high sensitivities (respectively 94% and 100%). Echocardiography combined with venous ultrasonography using a portable ultrasound device is a reliable method for screening patients with suspected PE referred to an emergency department, especially in patients with dyspnea or with high clinical probability. [source]


Emergency Physician,Verified Out-of-hospital Intubation: Miss Rates by Paramedics

ACADEMIC EMERGENCY MEDICINE, Issue 6 2004
James H. Jones MD
Abstract Objectives: To prospectively quantify the number of unrecognized missed out-of-hospital intubations by ground paramedics using emergency physician verification as the criterion standard for verification of endotracheal tube placement. Methods:The authors performed an observational, prospective study of consecutive intubated patients arriving by ground emergency medical services to two urban teaching hospitals. Endotracheal tube placement was verified by emergency physicians and evaluated by using a combination of direct visualization, esophageal detector device (EDD), colorimetric end-tidal carbon dioxide (ETCO2), and physical examination. Results: During the six-month study period, 208 out-of-hospital intubations by ground paramedics were enrolled, which included 160 (76.9%) medical patients and 48 (23.1%) trauma patients. A total of 12 (5.8%) endotracheal tubes were incorrectly placed outside the trachea. This comprised ten (6.3%) medical patients and two (4.2%) trauma patients. Of the 12 misplaced endotracheal tubes, a verification device (ETCO2 or EDD) was used in three cases (25%) and not used in nine cases (75%). Conclusions: The rate of unrecognized, misplaced out-of-hospital intubations in this urban, midwestern setting was 5.8%. This is more consistent with results of prior out-of-hospital studies that used field verification and is discordant with the only other study to exclusively use emergency physician verification performed on arrival to the emergency department. [source]


Planarization of Polymeric Field-Effect Transistors: Improvement of Nanomorphology and Enhancement of Electrical Performance

ADVANCED FUNCTIONAL MATERIALS, Issue 14 2010
Kumar A. Singh
Abstract The planarization of bottom-contact organic field-effect transistors (OFETs) resulting in dramatic improvement in the nanomorphology and an associated enhancement in charge injection and transport is reported. Planar OFETs based on regioregular poly(3-hexylthiophene) (rr-P3HT) are fabricated wherein the Au bottom-contacts are recessed completely in the gate-dielectric. Normal OFETs having a conventional bottom-contact configuration with 50-nm-high contacts are used for comparison purpose. A modified solvent-assisted drop-casting process is utilized to form extremely thin rr-P3HT films. This process is critical for direct visualization of the effect of planarization on the polymer morphology. Atomic force micrographs (AFM) show that in a normal OFET the step between the surface of the contacts and the gate dielectric disrupts the self-assembly of the rr-P3HT film, resulting in poor morphology at the contact edges. The planarization of contacts results in notable improvement of the nanomorphology of rr-P3HT, resulting in lower resistance to charge injection. However, an improvement in field-effect mobility is observed only at short channel lengths. AFM shows the presence of well-ordered nanofibrils extending over short channel lengths. At longer channel lengths the presence of grain boundaries significantly minimizes the effect of improvement in contact geometry as the charge transport becomes channel-limited. [source]


Monitoring of the internalization of neuropeptide Y on neuroblastoma cell line SK-N-MC

FEBS JOURNAL, Issue 17 2000
Marlies Fabry
Neuropeptide Y (NPY) is an important neuromodulator in the central and peripheral nervous system. The peptide acts through different NPY receptor subtypes (Y1,Y5, y6) that belong to the family of G protein-coupled receptors. In general, cellular responses to prolonged exposure to agonists of G protein-coupled receptors are attenuated, often through internalization of the receptors and their bound ligands. In this study, a fluorescent labeled NPY derivative was synthesized and characterized to investigate the internalization of NPY in the human neuroblastoma cell line SK-N-MC. Internalization was proven by binding experiments and subsequent acidic washing as well as by direct visualization by means of confocal laser scanning microscopy. Approximately 20,30% of the fluorescent labeled NPY and a tritium-marked NPY were resistant to acid removal of cell surface-bound ligands indicating internalization. Extracellular fluorescent labeled NPY was found to be distributed heterogeneously in a clustered pattern, which suggests that the ligand-receptor complex is collected in pits and caveolae followed by endocytosis. [source]


Direct fluorescence visualization of clinically occult high-risk oral premalignant disease using a simple hand-held device

HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 1 2007
Catherine F. Poh DDS
Abstract Background A considerable proportion of oral cancer and precancer is not clinically apparent and could contribute significantly to the late diagnosis and high mortality of oral cancer. A simple method to identify such occult change is needed. Methods Patients in the Oral Dysplasia Clinics at British Columbia are currently being examined with a simple hand-held device that permits the direct visualization of alterations to autofluorescence in the oral cavity. Tissue showing loss of autofluorescence is biopsied. Results We present 3 representative cases in which occult lesions were identified with fluorescence visualization during longitudinal follow-up, resulting in the diagnosis of a primary dysplasia in case 1, a second primary cancer in case 2, and cancer recurrence in case 3. Conclusions This is the first report of the diagnosis of occult oral disease using a simple noninvasive device. These early examples indicate the potential value of this technology to guide the management of patients with oral lesions, facilitating the detection of high-risk changes not apparent with white-light visualization. © 2006 Wiley Periodicals, Inc. Head Neck, 2006 [source]


Unsteady free convection,radiation flow over a vertical wall embedded in a porous medium

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 11 2008
Joaquín Zueco
Abstract A numerical solution for the transient two-dimensional free convection flow of viscous dissipative fluid over an infinite vertical plate through a porous medium bounded, taking into account the thermal radiation, is analysed. The fluid is grey, and acts as a radiation emitting and absorbing (but non-scattering) medium. The influence of the non-dimensional parameters such as the Forchheimer coefficient (Fo), the permeability parameter (P), the Eckert number (Ec) and the radiation parameter (R) on the velocity, temperature, Nusselt number and on the time taken to reach the steady state is studied. The possibility of non-Darcy flow is also analysed. The numerical method employed, network simulation method, is based on an electro-thermal analogy and permits the direct visualization and evolution of the local and/or integrated transport variables (velocities, temperatures and fluxes) at any point or section of the medium. The numerical solutions of this work have been compared with the existing information in the literature with good agreement. Copyright © 2007 John Wiley & Sons, Ltd. [source]


Combinatorial Fabrication of Fluorescent Patterns with Metal Ions Using Soft Lithography,

ADVANCED MATERIALS, Issue 8 2006
L. Basabe-Desmonts
A new combinatorial methodology for the fabrication and direct visualization of fluorescent and metal-ion micrometer patterns is presented. Microcontact printing is used to transfer different metal salts onto a variety of fluorescent monolayers on glass (see figure). [source]


Identification and Characterization of Atrioventricular Parasympathetic Innervation in Humans

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 8 2002
KARA J. QUAN M.D.
AV Parasympathetic Innervation.Introduction: We hypothesized that in humans there is an epicardial fat pad from which parasympathetic ganglia supply the AV node. We also hypothesized that the parasympathetic nerves innervating the AV node also innervate the right atrium, and the greatest density of innervation is near the AV nodal fat pad. Methods and Results: An epicardial fat pad near the junction of the left atrium and right inferior pulmonary vein was identified during cardiac surgery in seven patients. A ring electrode was used to stimulate this fat pad intraoperatively during sinus rhythm to produce transient complete heart block. Subsequently, temporary epicardial wire electrodes were sutured in pairs on this epicardial fat pad, the high right atrium, and the right ventricle by direct visualization during coronary artery bypass surgery in seven patients. Experiments were performed in the electrophysiology laboratory 1 to 5 days after surgery. Programmed atrial stimulation was performed via an endocardial electrode catheter advanced to the right atrium. The catheter tip electrode was moved in 1-cm concentric zones around the epicardial wires by fluoroscopic guidance. Atrial refractoriness at each catheter site was determined in the presence and absence of parasympathetic nerve stimulation (via the epicardial wires). In all seven patients, an AV nodal fat pad was identified. Fat pad stimulation during and after surgery caused complete heart block but no change in sinus rate. Fat pad stimulation decreased the right atrial effective refractory period at 1 cm (280 ± 42 msec to 242 ± 39 msec) and 2 cm (235 ± 21 msec to 201 ± 11 msec) from the fat pad (P = 0.04, compared with baseline). No significant change in atrial refractoriness occurred at distances > 2 cm. The response to stimulation decreased as the distance from the fat pad increased. Conclusion: For the first time in humans, an epicardial fat pad was identified from which parasympathetic nerve fibers selectively innervate the AV node but not the sinoatrial node. Nerves in this fat pad also innervate the surrounding right atrium. [source]


A systematic review on the clinical diagnosis of gastrointestinal stromal tumors

JOURNAL OF SURGICAL ONCOLOGY, Issue 5 2008
Marco Scarpa MD
Abstract Background The aim of this work was to assess the prevalence of symptoms of gastrointestinal stromal tumors (GISTs) and the diagnostic yield of clinical procedures for its diagnosis. Methods Medical databases were consulted between 1998 and 2006 for potentially relevant publications. All studies dealing with the clinical presentation of GIST and related diagnostic procedures were included. Two researchers worked independently on the study selection, quality assessment, data extraction, and analysis phases of the study. Results Forty-six observational studies were included with a total of 4,534 patients. Gastrointestinal bleeding was the most common clinical presentation. Twenty studies provided adequate information on the diagnostic yield of various procedures. The pooled diagnostic yield of endoscopy,+,mucosal biopsy and of intestinal contrast radiography was 33.8% (0,100%) and 35.1% (11,100%), respectively, while that of EUS and that of EUS-FNA was 68.7% (40,100%) and 84.0% (73.8,100%), respectively. Abdominal CT scan and MRI had similar pooled diagnostic yields: 73.6% (34.8,100%), and 91.7% (75,100%), respectively. Conclusion Endoscopy,+,mucosal biopsy should be reserved to patients with gastrointestinal bleeding. EUS-FNA provides direct visualization of the neoplasm and adequate samples for molecular diagnosis. EUS, abdominal CT and MRI may be considered valid alternatives whenever EUS-FNA is unavailable or a cytological diagnosis is unnecessary. J. Surg. Oncol. 2008;98:384,392. © 2008 Wiley-Liss, Inc. [source]


A perspective on murine keratinocyte stem cells as targets of chemically induced skin cancer

MOLECULAR CARCINOGENESIS, Issue 8 2007
Thaned Kangsamaksin
Abstract Although ideas on the stem cell origins of cancer date more than one hundred years, critical evidence to support these theories is largely lacking. Our objective here is to outline our historical perspective on keratinocyte stem cells in the cutaneous epithelium and to summarize specific evidence suggesting that epithelial stem cells may contribute to chemically induced skin cancer. We note that, while strong evidence does support this hypothesis, experiments in progress may provide direct visualization of tumors derived from hair follicle stem cells. © 2007 Wiley-Liss, Inc. [source]


Direct Visualization of Abasic Sites on a Single DNA Molecule Using Fluorescence Microscopy,

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2002
Tamaki Hirose
ABSTRACT A new method was developed to allow direct visualization of damaged sites on individual DNA molecules. Fluorescence in situ hybridization on extended DNA molecules was modified to detect a single abasic site. Abasic sites were specifically labeled with a biotinylated aldehyde-reactive probe and fluorochrome-conjugated streptavidin. The light emitted by a single fluorochrome,DNA complex was calibrated. The number of abasic sites on the DNA molecule was estimated by counting each fluorochrome,DNA complex. The present study directly visualized and characterized the abasic sites of single DNA molecules. [source]


Cross-sectional AFM study of etching kinetics of oxidized porous silicon

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2004
J. C. Poler
Abstract We have studied the morphology and etching kinetics of partially oxidized porous silicon films. Film morphology and thickness was measured using cross-sectional atomic force microscopy. Air and UV-ozone oxidized porous silicon films were etched in buffered hydrofluoric acid. The observed etching rate was much faster than expected for a bulk film. These data consist of: direct visualization of cluster formation, enhanced etching rates and subsequent analysis of the liberated nanoparticles, and consistent with a mesoporous morphology of undulating Si nanowires. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Model for Ultrasound-Assisted Lumbar Puncture Training

ACADEMIC EMERGENCY MEDICINE, Issue 2009
Melissa Bollinger
Lumbar puncture is an important diagnostic procedure in emergency medicine. Data have been published showing improved success rate with ultrasound assistance and the ability of emergency medicine physicians to recognize sonographic lumbar spinous anatomy. However, with educational models and the push for improved patient safety, procedural skills should be practiced on phantoms rather than the "see one, do one, teach one" of the past. There are no currently available phantoms for ultrasound-assisted lumbar puncture training. We have produced a phantom that can be used to train physicians on ultrasound-assisted lumbar puncture with respect to both imaging and procedural competency. A plastic fluid-filled bladder was immersed in gelled opacified mineral oil, a safe and easily used tissue mimic that obscures direct visualization of structures. Spinous anatomy is replicated with the use of wooden struts supporting wooden disks that mimic lumbar spinous processes. The spine analog was mounted over the plastic bladder and surrounded with gelled mineral oil. The phantom produces images similar to human lumbar anatomy. The phantom allows insertion of spinal needles into the "interspinous spaces" with inability to pass the needle outside of those locations. Fluid collection and repeated punctures can be performed on the phantom. Appearance and performance of the phantom were evaluated by physicians with expertise in ultrasound-assisted lumbar puncture. The only limitation is that external appearance is not realistic. This model performs well, is made from readily available materials, and can be used to train physicians in ultrasound-assisted lumbar puncture. [source]


A Recombinant Bacteriophage-Based Assay for the Discriminative Detection of Culturable and Viable but Nonculturable Escherichia coli O157:H7

BIOTECHNOLOGY PROGRESS, Issue 3 2006
Raheela Awais
A previously green fluorescent protein (GFP)-labeled PP01 virulent bacteriophage, specific to Escherichia coli O157:H7, was used to construct lysozyme-inactivated GFP-labeled PP01 phage (PP01e - /GFP). The new recombinant phage lacked lytic activity because of the inactivation of gene e, which produces the lysozyme responsible for cell lysis. Gene e was inactivated by inserting an amber stop codon. Prolonged incubation ofE. coli O157:H7 cells with PP01e - /GFP did not lead to cell lysis, while the propagation of PP01e - /GFP in host cells increased the intensity of green fluorescence. Retention of cell morphology and increase in fluorescence enabled the direct visualization and enumeration of E. coli O157:H7 cells within an hour. The PP01e - /GFP system, when combined with nutrient uptake analysis, further allowed the discriminative detection of culturable, viable but nonculturable (VBNC), and dead cells in the stress-induced aquatic environment. Stress-induced cells, which retained culturability, allowed phage propagation and produced bright green florescence. Nonculturable cells (VBNC and dead) allowed only phage adsorption but no proliferation and remained low fluorescent. The low-fluorescent nonculturable cells were further differentiated into VBNC and dead cells on the basis of nutrient uptake analysis. The low-fluorescent cells, which grew in size by nutrient incorporation during prolonged incubation in nutrient medium, were defined as metabolically active and in the VBNC state. The elongated VBNC cells were then easily recognizable from dead cells. The proposed assay enabled the detection and quantification of VBNC cells. Additionally, it revealed the proportion of culturable to VBNC cells within the population, as opposed to conventional techniques, which demonstrate VBNC cells as a differential value of the total viable count and the culturable cell count. [source]


Dynamic gadolinium-enhanced magnetic resonance urography for assessing drainage in dilated pelvicalyceal systems with moderate renal function: preliminary results and comparison with diuresis renography

BJU INTERNATIONAL, Issue 6 2004
W.C.W. Chu
OBJECTIVE To evaluate the use of dynamic gadolinium diethylenetriaminepenta-acetic acid (DTPA)-enhanced magnetic resonance urography (Gd-MRU) for assessing kidneys with markedly dilated pelvicalyceal systems and impaired function. PATIENTS AND METHODS Eight children (mean age 30 months, sd 25) were assessed, diagnosed as having gross unilateral hydronephrosis with a mean (sd) anteroposterior renal pelvic diameter of 36 (7) mm and reduced (30,40%) renal function. Dynamic Gd-MRU was performed after the patients were pre-loaded with intravenous fluid and diuretics, and comprised a dynamic T1-weighted sequence after Gd-DTPA (0.1 mmol/kg body weight) was administered, with a time-intensity curve of each kidney produced. Drainage was diagnosed by a clearly declining time-intensity curve and direct visualization of contrast medium within the ureter in several frames. High-grade or complete obstruction was diagnosed when drainage of contrast medium could not be detected. Gd-MRU results were compared with diuresis radionuclide (mercapto-acetyltriglycine, MAG3) renography within the same week. Unobstructive units detected by Gd-MRU were treated conservatively with a close follow-up by ultrasonography and radionuclide studies. RESULTS Diuresis MAG3 renography showed drainage in three dilated units and poor washout in five; in contrast, Gd-MRU showed drainage in seven dilated systems (three showed poor washout by MAG3), and obstruction in the remaining case. The unobstructed units detected by MRU under conservative treatment thus showed no further deterioration of renal function or progressive hydronephrosis in the subsequent follow-up (mean 18 months, range 15,23). CONCLUSION These preliminary results suggest that dynamic Gd-MRU is a useful noninvasive imaging method in distinguishing obstructive from unobstructive dilated systems, particularly in patients with hydronephrosis and reduced renal function. [source]


Success of Ultrasound-guided Peripheral Intravenous Access with Skin Marking

ACADEMIC EMERGENCY MEDICINE, Issue 8 2008
Jessica R. Resnick MD
Abstract Objectives:, The most effective technique for ultrasound-guided peripheral intravenous access (USGPIVA) is unknown. In the traditional short-axis technique (locate, align, puncture [LAP]), the target vessel is aligned in short axis with the center of the transducer. The needle is then directed toward the target under real-time ultrasound (US) guidance. Locate, align, mark, puncture (LAMP) requires the extra step of marking the skin at two points over the path of the vein and proceeding with direct visualization as in LAP. The difference in success between these two techniques was compared among variably experienced emergency physician and emergency nurse operators. Methods:, Subjects in an urban academic emergency department (ED) were randomized to obtain intravenous (IV) access using either LAP or LAMP after two failed blind attempts. Primary outcomes were success of the procedure and time to complete the procedure in variably experienced operators. Results:, A total of 101 patients were enrolled. There was no difference in success between LAP and LAMP, even among the least experienced operators. Of successful attempts, LAMP took longer than LAP (median 4 minutes, interquartile range [IQR] 4,10.5 vs. median 2.9 minutes, IQR 1.6,7; p = 0.004). Only the most experienced operators were associated with higher levels of success (first attempt odds ratio [OR] 6.64; 95% confidence interval [CI] = 2 to 22). Overall success with up to two attempts was 73%. Complications included a 2.8% arterial puncture rate and 12% infiltration rate. Conclusions:, LAMP did not improve success of USGPIVA in variably experienced operators. Experience was associated with higher rates of success for USGPIVA. [source]


A Two-Photon Fluorescent Probe for Lipid Raft Imaging: C-Laurdan

CHEMBIOCHEM, Issue 5 2007
Hwan Myung Kim
Abstract The lipid-rafts hypothesis proposes that naturally occurring lipid aggregates exist in the plane of membrane that are involved in signal transduction, protein sorting, and membrane transport. To understand their roles in cell biology, a direct visualization of such domains in living cells is essential. For this purpose, 6-dodecanoyl-2-(dimethylamino)naphthalene (laurdan), a membrane probe that is sensitive to the polarity of the membrane, has often been used. We have synthesized and characterized 6-dodecanoyl-2-[N -methyl- N -(carboxymethyl)amino]naphthalene (C-laurdan), which has the advantages of greater sensitivity to the membrane polarity, a brighter two-photon fluorescence image, and reflecting the cell environment more accurately than laurdan. Lipid rafts can be visualized by two-photon microscopy by using C-laurdan as a probe. Our results show that the lipid rafts cover 38,% of the cell surface. [source]


PaCE: a technique to avoid subretinal fluid drainage in retinal detachment surgery

ACTA OPHTHALMOLOGICA, Issue 1 2006
Manzar Saeed
Abstract. Purpose:,Subretinal fluid (SRF) drainage and thus the potential complications of this procedure during scleral buckling can be avoided by inducing SRF absorption preoperatively. The technique described in this series is named PaCE (Pneumatic Cryo Explant). Methods:,A total of 22 eyes of 22 patients with primary bullous rhegmatogenous retinal detachment (RRD) were included in this prospective non-comparative case trial. All satisfied specific inclusion criteria similar to those used in previous pneumatic retinopexy (PR) studies. Under direct visualization, 0.3 ml C3F8 100% was injected into the vitreous cavity through the pars plana. Postoperative posturing was encouraged. Retinopexy with either cryotherapy or laser was performed, combined with scleral buckling (SB) when the SRF was absorbed. Avoidance of SRF drainage and persistent reattachment of the retina at the end of the 12-month follow-up was considered a successful outcome. A change in vision by one line (logMAR) was considered significant. Results:,Resolution of SRF before retinopexy and the SB procedure was achieved in 20 of 22 eyes (90.9%) and hence SRF drainage was not required. Visual improvement was achieved in 95% of cases. One eye (4.5%) lost vision due to a total RD after gas injection (further surgery was not carried out). Conclusion:,PaCE should be considered in any suitable case of primary RRD where SRF drainage is deemed necessary. The potential complications associated with this procedure are relatively less serious and it does not compromise the viability of subsequent procedures. [source]


Difficult intubation of a child through laryngeal mask airway with two tracheal tubes

ACTA PAEDIATRICA, Issue 12 2006
TANIL KENDIIRLI
Abstract Difficult tracheal intubation occurs infrequently. It is estimated that difficult laryngoscopy occurs in 1,2% of patients. Tracheal intubation of especially small infants can be challenging. When faced with a difficult airway, intubation through a laryngeal mask airway is one method of obtaining a secure airway. Here, we report a 23-mo-old girl with chronic lung disease and severe pneumonia, who was admitted to our paediatric intensive care unit. Since the patient could not be intubated by the standard method, because her larynx was up and forward, she was intubated successfully with a laryngeal mask airway through which two consecutive tracheal tubes were inserted. Conclusion: Laryngeal mask airway has an important role as a back-up device in case direct visualization of the larynx is not possible. [source]


Identification of post-transplant lymphocele using lymphatic mapping with isosulphane blue

CLINICAL TRANSPLANTATION, Issue 1 2009
A. Cakmak
Abstract:, Lymphocele development after renal transplantation is a well-recognized complication that occurs with the incidence of 0.6,18%. Although the majority of patients are asymptomatic, post-renal transplant lymphocele continues to be a major cause of morbidity if it is left untreated. The standard approach for the treatment of symptomatic lymphoceles is accepted to be laparoscopic or open marsupialization in many centers if simple drainage and conservative measures fail. However, marsupialization is almost impossible under certain circumstances, such as in the case of excessive abdominal adhesions. Hence, direct visualization of the lymphatic leak and suture ligation may become inevitable, which is usually a challenging procedure for the surgeon. Herein we report a case of post-renal transplant lymphocele treated by the direct identification and suture ligation of injured lymphatic vessel using a new method similar to sentinel lymph node detection using the dye isosulphane blue. [source]