Scanning near-field fluorescence resonance energy transfer microscopy.
A new microscopic technique is demonstrated that combines attributes from both near-field scanning optical microscopy (NSOM) and fluorescence resonance energy transfer (FRET). The method relies on attaching the acceptor dye of a FRET pair to the end of a near-field fiber optic probe. Light exiting the NSOM probe, which is nonresonant with the acceptor dye, excites the donor dye introduced into a sample. As the tip approaches the sample containing the donor dye, energy transfer from the excited donor to the tip-bound acceptor produces a red-shifted fluorescence. By monitoring this red-shifted acceptor emission, a dramatic reduction in the sample volume probed by the uncoated NSOM tip is observed. This technique is demonstrated by imaging the fluorescence from a multilayer film created using the Langmuir-Blodgett (LB) technique. The film consists of L-alpha-dipalmitoylphosphatidylcholine (DPPC) monolayers containing the donor dye, fluorescein, separated by a spacer group of three arachidic acid layers. A DPPC monolayer containing the acceptor dye, rhodamine, was also transferred onto an NSOM tip using the LB technique. Using this modified probe, fluorescence images of the multilayer film reveal distinct differences between images collected monitoring either the donor or acceptor emission. The latter results from energy transfer from the sample to the NSOM probe. This method is shown to provide enhanced depth sensitivity in fluorescence measurements, which may be particularly informative in studies on thick specimens such as cells. The technique also provides a mechanism for obtaining high spatial resolution without the need for a metal coating around the NSOM probe and should work equally well with nonwaveguide probes such as atomic force microscopy tips. This may lead to dramatically improved spatial resolution in fluorescence imaging. (+info
Disinfection of upper gastrointestinal fibreoptic endoscopy equipment: an evaluation of a cetrimide chlorhexidine solution and glutaraldehyde.
There is little information available on the bacteriological contamination of upper gastrointestinal fibreoptic endoscopes during routine use and the effects of 'disinfecting solutions'. A bacteriological evaluation was therefore made of cleaning an endoscope and its ancillary equipment with (1) water, (2) an aqueous solution of 1% cetrimide with 0.1% chlorhexidine, and (3) activated aqueous 2% glutaraldehyde. All equipment, but particularly the endoscope itself, was found to be heavily contaminated after use with a wide variety of organisms of which 53% were Gram positive. Cleaning the endoscope and ancillary equipment with water and the cetrimide/chlorhexidine solution alone or in combination was inadequate to produce disinfection but immersion in glutaraldehyde for two minutes consistently produced sterile cultures with our sampling technique. A rapid and simple method for disinfection of endoscopic equipment is therefore recommended and we think this is especially suitable for busy endoscopy units. (+info
Correlating fibreoptic nasotracheal endoscopy performance and psychomotor aptitude.
We have investigated the correlation between the scores attained on computerized psychometric tests, measuring psychomotor and information processing aptitudes, and learning fibreoptic endoscopy with the videoendoscope. Sixteen anaesthetic trainees performed two adaptive tracking tasks (ADTRACK 2 and ADTRACK 3) and one information management task (MAZE) from the MICROPAT testing system. They then embarked on a standardized fibreoptic training programme during which they performed 15 supervised fibreoptic nasotracheal intubations on anaesthetized oral surgery patients. There was a significant correlation between the means of the 15 endoscopy times and both ADTRACK 2 (r = -0.599, P = 0.014) and ADTRACK 3 (r = -0.589, P = 0.016) scores. The correlation between the means of the 15 endoscopy times and MAZE scores was not significant. The ratios of the mean endoscopy time for the last seven endoscopies to the mean endoscopy time for the first seven endoscopies were not significantly correlated with ADTRACK 2, ADTRACK 3 or MAZE scores. Psychomotor abilities appeared to be determinants of trainees' initial proficiency in endoscopy, but did not appear to be determinants of trainees' rates of progress during early fibreoptic training. (+info
Pharyngeal mucosal pressures, airway sealing pressures, and fiberoptic position with the intubating versus the standard laryngeal mask airway.
BACKGROUND: The tube of the intubating laryngeal mask (ILM) is more rigid than the standard laryngeal mask airway (LMA), and the authors have tested the hypothesis that pharyngeal mucosal pressures, airway sealing pressures, and fiberoptic position are different when the two devices are compared. METHODS: Twenty anesthetized, paralyzed adults were randomly allocated to receive either the LMA or ILM for airway management. Microchip sensors were attached to the size 5 LMA or ILM at locations corresponding to the pyriform fossa, hypopharynx, base of tongue, posterior pharynx, and distal and proximal oropharynx. Mucosal pressures, airway sealing pressures, and fiberoptic positioning were recorded during inflation of the cuff from 0 to 40 ml in 10-ml increments. RESULTS: Airway sealing pressures were higher for the ILM (30 vs. 23 cm H2O), but epiglottic downfolding was more common (56% vs. 26%). Pharyngeal mucosal pressures were much higher for the ILM at five of six locations. Mean mucosal pressures in the distal oropharynx for the ILM were always greater than 157 cm H2O, regardless of cuff volume. There was no correlation between mucosal pressures and airway sealing pressures at any location for the LMA, but there was a correlation at three of six locations for the ILM. CONCLUSIONS: The ILM provides a more effective seal than the LMA, but pharyngeal mucosal pressures are higher and always exceed capillary perfusion pressure. The ILM is unsuitable for use as a routine airway and should be removed after its use as an airway intubator. (+info
Pacemaker lead extraction with the laser sheath: results of the pacing lead extraction with the excimer sheath (PLEXES) trial.
OBJECTIVES: The purpose of this study was to evaluate the safety and effectiveness of pacemaker lead extraction with the excimer sheath in comparison to nonlaser lead extraction. BACKGROUND: Fibrotic attachments that develop between chronically implanted pacemaker leads and to the venous, valvular and cardiac structures are the major obstacles to safe and consistent lead extraction. Locking stylets and telescoping sheaths produce a technically demanding but effective technique of mechanically disrupting the fibrosis. However, ultraviolet excimer laser light dissolves instead of tearing the tissue attachments. METHODS: A randomized trial of lead extraction was conducted in 301 patients with 465 chronically implanted pacemaker leads. The laser group patients had the leads removed with identical tools as the nonlaser group with the exception that the inner telescoping sheath was replaced with the 12-F excimer laser sheath. Success for both groups was defined as complete lead removal with the randomized therapy without complications. RESULTS: Complete lead removal rate was 94% in the laser group and 64% in the nonlaser group (p = 0.001). Failed nonlaser extraction was completed with the laser tools 88% of the time. The mean time to achieve a successful lead extraction was significantly reduced for patients randomized to the laser tools, 10.1 +/- 11.5 min compared with 12.9 +/- 19.2 min for patients randomized to nonlaser techniques (p < 0.04). Potentially life-threatening complications occurred in none of the nonlaser and three of the laser patients, including one death (p = NS). CONCLUSIONS: Laser-assisted pacemaker lead extraction has significant clinical advantages over extraction without laser tools and is associated with significant risks. (+info
Primary care physicians' decisions to perform flexible sigmoidoscopy.
OBJECTIVE: This study was designed to identify factors that influence primary care physicians' willingness to perform flexible sigmoidoscopy. MEASUREMENTS: Using a mailed questionnaire, we surveyed all 161 primary care physicians participating in a large health care system. We obtained information on training, current practice patterns, beliefs about screening for colorectal cancer, and the influence of various factors on their decision whether or not to perform flexible sigmoidoscopy in practice. MAIN RESULTS: Of the 131 physicians included in the analysis, 68 (52%) reported training in flexible sigmoidoscopy, of whom 36 (53%) were currently performing flexible sigmoidoscopy in practice. Time required to perform flexible sigmoidoscopy, availability of adequately trained staff, and availability of flexible sigmoidoscopy services provided by other clinicians were identified most often as reasons not to perform the procedure in practice. Male physicians were more likely than female physicians to report either performing flexible sigmoidoscopy or desiring to train to perform flexible sigmoidoscopy (odds ratio 2.61; 95% confidence interval 1.10, 6.23). This observed difference appears to be mediated through different weighting of decision criteria by male and female physicians. CONCLUSIONS: Approximately half of these primary care physicians trained in flexible sigmoidoscopy chose not to perform this procedure in practice. Self-perceived inefficiency in performing office-based flexible sigmoidoscopy deterred many of these physicians from providing this service for their patients. (+info
Bronchoscopic therapy for mucosa-associated lymphoid tissue lymphoma of the trachea.
The tracheal tumor of a 74-year-old female was detected on bronchoscopy and histologically diagnosed as mucosa-associated lymphoid tissue (MALT) lymphoma. We successfully treated the tumor with endoscopic neodyminum-yttruim-aluminium-garnet (Nd-YAG) laser photoresection followed by local ethanol injection. This is the first case in which tracheal MALT lymphoma was successfully treated with bronchoscopy. Bronchoscopic therapy seems to be one of the most valuable strategies for treatment of MALT lymphomas of the central airway. (+info
Kaposi's sarcoma-associated herpesvirus infection in the lung in multicentric Castleman's disease.
A 32-year-old female was admitted for evaluation of multiple infiltrates on a chest radiograph. A diagnosis of multicentric Castleman's disease was made on the basis of typical clinical manifestations. Transbronchial lung biopsy (TBLB) revealed histological findings reported in lymphocytic interstitial pneumonia. Both the polymerase chain reaction and in situ hybridization with a probe specific for Kaposi's sarcoma-associated herpesvirus (KSHV) sequences demonstrated the presence of KSHV in the TBLB sample. (+info