Three-dimensional characterization of tethered microspheres by total internal reflection fluorescence microscopy.
Tethered particle microscopy is a powerful tool to study the dynamics of DNA molecules and DNA-protein complexes in single-molecule experiments. We demonstrate that stroboscopic total internal reflection microscopy can be used to characterize the three-dimensional spatiotemporal motion of DNA-tethered particles. By calculating characteristic measures such as symmetry and time constants of the motion, well-formed tethers can be distinguished from defective ones for which the motion is dominated by aberrant surface effects. This improves the reliability of measurements on tether dynamics. For instance, in observations of protein-mediated DNA looping, loop formation is distinguished from adsorption and other nonspecific events. (+info)
Laryngeal assessment in rheumatic disease patients.
Rheumatic diseases usually promote several systemic disorders, which can affect blood vessels, mucosa and serosa of the aerodigestive tract. Scarce laryngeal involvement has been described in these patients and this study aims at investigating laryngeal alterations found in patients with rheumatic diseases. STUDY DESIGN: Transversal cohort. MATERIAL AND METHOD: A transversal study was developed with systemic lupus erythematous, systemic sclerosis and mixed connective tissue disease's patients. They were evaluated by means of clinical examinations and videolaryngoestroboscopy. RESULTS: Twenty-seven patients were included in the study, 26 succeeded in completing the videolaryngoestroboscopy. Laryngeal abnormalities were seen in 11 of 12 patients with lupus, in all 11 patients with sclerodermia and in 3 patients with mixed connective tissue disease. Vocal fold bamboo node was observed in 5 patients and 92.3% of all patients presented laryngeal signs of gastroesophageal reflux disease. CONCLUSION: We noticed 5 vocal fold bamboo nodes and gastroesophageal reflux disease in almost all patients. (+info)
Stroboscopic illumination using light-emitting diodes reduces phototoxicity in fluorescence cell imaging.
Excited fluorophores produce reactive oxygen species that are toxic toward many live cells (phototoxicity) and accelerate bleaching of the fluorophores during the course of extended or repeated measurements (photobleaching). We recently developed an illumination system for fluorescence microscopy using a high power light-emitting diode (LED), which can emit short pulses of light (0.5-2 ms) to excite fluorophores. This system minimizes illumination time, thus reducing phototoxicity and photobleaching artifacts. To demonstrate the usefulness of the new system, we compared images of human sperm loaded with various fluorescent indicators and excited with either a conventional mercury lamp as a continuous excitation light source or the LED as a source of pulsed illumination. We found that sperm motility decreased rapidly and photobleaching was relatively rapid under continuous illumination, whereas under pulsed LED illumination, motility was maintained and photobleaching was much reduced. Therefore, fluorescence microscopy using LED-based pulsed illumination offers significant advantages for long-term live cell imaging, reducing the degree of phototoxicity, and extending the effective lifetime of fluorophores. (+info)
Profile of voice professionals seen in a tertiary health center.
Work-related laryngopathy may have negative consequences for voice professionals. AIM: To analyze the profile of voice professionals seen in a tertiary level hospital. STUDY DESIGN: a longitudinal historical cohort. METHODS: A retrospective analysis of patient files. Diagnosis was reached using videostroboscopy. RESULTS: 163 patients (119 females and 44 males) were seen. The mean age was 36.5 years. Professionals included spoken voice users (salesman, teachers, telemarketers, receptionists, health professionals) and singers. The most frequent diagnoses were: minor structural changes (33%), nodules (22%), Reinkes edema (10%), and polyps (6%). A correlation was observed between smoking, age and gender; there was an association between smoking and Reinkes edema, leucoplasia and tabagism, females and Reinkes edema, nodules and minor structural changes, and also between patients aged over 40 years and Reinkes edema, and patients under 40 with nodules, laryngitis, and minor structural changes. Symptoms lasted more than 6 months in 74% of patients. CONCLUSION: The profile of voice professionals seen in a tertiary hospital included spoken voice patients and singers. In our study minor structural changes predominated, followed by nodules, Reinke edema and polyps. (+info)
Is colour modulation an independent factor in human visual photosensitivity?
Considering that the role of colour in photosensitive epilepsy (PSE) remains unclear, we designed a study to determine the potential of different colours, colour combinations and white light to trigger photoparoxysmal responses (PPRs) under stringent controlled conditions. After assessing their photosensitivity to stroboscopic white light and black and white patterns, we studied 43 consecutive PSE patients (mean age 19 years, 34 women), using a specially designed colour stimulator. Stimuli included: pulse trains between 10 and 30 Hz of white light and of all primary colours, and also isoluminant alternating time-sequences of colours. Illuminance was kept constant at 100 lux. A progressive stepwise increase of the modulation-depth (MD) of the stimuli was used to determine PPRs threshold. Whereas all the 43 patients were found to be sensitive during the stroboscopic and pattern protocol, only 25 showed PPRs (Waltz's score >2) at least in one session when studied with the colour stimulator. Coloured stimuli elicited PPRs in all these patients, whereas white light did so only in 17 patients. Of the primary colours, red elicited more PPRs (54 in 22 patients) and at a lower MD (max Z-score 0.93 at 10 Hz). Of the alternating sequences, the red-blue was the most provocative stimulus, especially below 30 Hz (100% of patients, max Z-score: 1.65 at 15 Hz). Blue-green was the least provocative stimulus, since it elicited only seven PPRs in seven (28%) patients (max Z-score 0.44 at 10 Hz). Sensitivity to alternating colours was not correlated to sensitivity to individual colours. We conclude that colour sensitivity follows two different mechanisms: one, dependent on colour modulation, plays a role at lower frequencies (<30 Hz). Another, dependent on single-colour light intensity modulation correlates to white light sensitivity and is activated at higher frequencies. Our results suggest that the prescription of spectacles with coloured lenses, tailored to the patient, can be an effective preventative measure against visually induced seizures. (+info)
Diagnostic sensitivity and specificity of laryngoscopic signs of reflux laryngitis.
OBJECTIVE: To assess the diagnostic sensitivity and specificity of the laryngoscopic signs of reflux laryngitis. MATERIAL AND METHODS: Using original quantitative evaluation system, the laryngoscopic signs of 108 patients with reflux laryngitis and 90 healthy people were subjected to comparative analysis in this study. Summing up all evaluations of laryngeal changes, laryngoscopic reflux index was proposed. RESULTS: Mucosal lesions and edema of vocal cords along with mucosal lesions of the interarytenoid notch were found to be most significant for diagnostics of reflux laryngitis. Presence of mucosal lesions of the interarytenoid notch (roughness, hypertrophy, keratosis, granuloma) increases the odds ratio to attribute the patient to the reflux laryngitis patient group 21 times (OR=21.32, 95% CI 4.38-103.93; P<0.001). Mucosal lesions (hypertrophy, keratosis, granuloma) and edema of vocal cords were determined as the most sensitive and rather specific laryngoscopic signs. Roughness and grade II hypertrophy of interarytenoid notch were found to be the most specific (98%) and sensitive (56%) laryngoscopic signs of reflux laryngitis. Abnormal values of laryngoscopic reflux index (higher than 5 points) reflect a diagnostic sensitivity of 96% and specificity of 97% differentiating patients with reflux laryngitis from healthy persons. CONCLUSIONS: Mucosal lesions and edema of vocal cords along with mucosal lesions of the interarytenoid notch are found to be the most significant laryngoscopic signs for diagnostics of reflux laryngitis. Laryngoscopic reflux index was found to be the most sensitive and specific diagnostic criterion for reflux laryngitis. (+info)
The neurotoxic effects of manganese on the dopaminergic innervation of the gill of the bivalve mollusc, Crassostrea virginica.
Qualification of a quantitative laryngeal imaging system using videostroboscopy and videokymography.
OBJECTIVES: We sought to determine whether full-cycle glottal width measurements could be obtained with a quantitative laryngeal imaging system using videostroboscopy, and whether glottal width and vocal fold length measurements were repeatable and reliable. METHODS: Synthetic vocal folds were phonated on a laboratory bench, and dynamic images were obtained in repeated trials by use of videostroboscopy and videokymography (VKG) with an imaging system equipped with a 2-point laser projection device for measuring absolute dimensions. Video images were also obtained with an industrial videoscope system with a built-in laser measurement capability. Maximum glottal width and vocal fold length were compared among these 3 methods. RESULTS: The average variation in maximum glottal width measurements between stroboscopic data and VKG data was 3.10%. The average variations in width measurements between the clinical system and the industrial system were 1.93% (stroboscopy) and 3.49% (VKG). The variations in vocal fold length were similarly small. The standard deviations across trials were 0.29 mm for width and 0.48 mm for length (stroboscopy), 0.18 mm for width (VKG), and 0.25 mm for width and 0.84 mm for length (industrial). CONCLUSIONS: For stable, periodic vibration, the full extent of the glottal width can be reliably measured with the quantitative videostroboscopy system. (+info)