Analgesia and sedation in fiber optic bronchoscopy.
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Administration, Intranasal↗
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Results for “Fiber Optic Technology”
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Detection of pathogen Escherichia coli O157:H7 AT 70 cells/mL using antibody-immobilized biconical tapered fiber sensors.
Optical fibers (core diameter 8 microm, cladding diameter 125 microm) was tapered to a waist diameter in the range of 8-12 microm, and then a monoclonal antibody to the pathogen, Escherichia coli O157:H7 was covalently bonded to the surface of the tapered region. Using 470 nm light, the taper was exposed to various concentrations (7 x 10(7), 7 x 10(5), 7 x 10(3), and 70 cells/mL) of the pathogen, and the sensor showed changes in transmitted light as the antigen attached to the antibody on the taper surface. The response was equal and opposite when the pathogen was released from the surface using a low pH buffer. The magnitude of the change was inversely proportional to the concentration of the pathogen. The sensor showed good sensitivity at as low a concentration as 70 cells/mL. The antibody-immobilized taper sensor was also exposed to a mixture of the pathogen and a non-pathogenic variant (JM101) at 0%, 50% and 70% by concentration. The sensor showed good selectivity to the pathogenic antigen. A first order attachment kinetic model is proposed to quantify the rate of attachment of pathogen to the sensor surface. The kinetic rate constant (k) of E. coli O157:H7 to the fiber was found to vary in the range of (2.5-6.1) x 10(-9) min(-1) (cells/mL)(-1).
Antibodies, Bacterial↗
Rapid PCR confirmation of E. coli O157:H7 after evanescent wave fiber optic biosensor detection.
Escherichia coli O157:H7 is an enteric pathogen of public health importance, which is monitored by several government agencies. Many rapid detection tests have been developed to identify foodstuff and water supplies contaminated by E. coli O157:H7. However, these methods can be time consuming (24-48 h) due to the need to culture the bacteria to confirm detection results. Fiber optic biosensors can rapidly detect pathogens from complex matrices, yet confirmation tests can take up to 10h to complete. In addition, fiber optic biosensors can also be used to reduce the impact of PCR inhibitors present in complex matrices such as food and water. This paper presents methodologies to reduce the time necessary for confirmation from 10 to about 2 h, by direct PCR of bacteria from the fiber optic waveguides without the need for culture or enrichment steps.
Antibodies, Bacterial↗
Novel BOD optical fiber biosensor based on co-immobilized microorganisms in ormosils matrix.
A biochemical oxygen demand (BOD) sensor has been developed, which is based on an immobilized mixed culture of microorganisms combined with a dissolved oxygen (DO) optical fiber. The sensing film for BOD measurement consists of an organically-modified silicate (ORMOSIL) film embedded with tri(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) perchlorate and three kinds of seawater microorganisms immobilized on a polyvinyl alcohol sol-gel matrix. The BOD measurements were carried out in the kinetic mode inside a light-proof cell and with constant temperature. Measurements were taken for 3 min followed by 10 min recovery time in 10 mg/L glucose/glutamate (GGA) BOD standard solution, and the range of determination was from 0.2 to 40 mg/L GGA. The effects of temperature, pH and sodium chloride concentration on the BOD sensing films were studied. BOD values estimated by this optical BOD sensing film correlate well with those determined by the conventional BOD5 method for seawater samples.
Amino Acids↗
Laboratory-scale application of fiber optic transflection dip probe (FOTDP) for in situ monitoring of gas phase ozone in unsaturated porous media.
A fiber optic transflection dip probe (FOTDP) system was developed for in situ and real-time monitoring of the transport of gas phase ozone in unsaturated porous media. A unique property of this system is the employment of a dip probe, which is inserted within the porous media. At the probe's tip, incoming light interacts with gas phase ozone and is partially reflected back into the probe by a mirror attached to the tip. Calibration of the FOTDP system was successfully carried out with various ozone concentrations using a column packed with glass beads. The ozone breakthrough curves (BTCs) were obtained by converting normalized UV intensities into gas phase ozone concentrations. The FOTDP system worked well for in situ monitoring of gas phase ozone using a column packed with sand under various water saturations in the presence of SOM and reflected the ideal transport phenomena of gas phase ozone for various flow rates.
Animals↗
Techniques to maximize flexible ureteroscope longevity.
OBJECTIVES: To assess methods to improve the longevity and durability of flexible ureteroscopes by using the ureteral access sheath, 200-microm holmium laser fiber, and nitinol baskets or graspers during routine ureteroscopic procedures. Despite adequate advances in fiberoptics and endoscope design, the decreased size of currently available flexible ureteroscopes makes damage inevitable after repeated use. However, new auxiliary tools may be able to enhance ureteroscope durability. METHODS: The indications for performing flexible ureteroscopy were proximal ureteral stones (n = 32), renal calculi (n = 59), treatment of upper tract transitional cell carcinoma (n = 3), evaluation of hematuria or filling defect (n = 7), and treatment of ureteral strictures or ureteropelvic junction obstruction (n = 8). Using four new 7.5F flexible ureteroscopes, we prospectively evaluated the number of passes of each ureteroscope until more than 20 optical fibers were broken, more than a 25 degrees loss of deflection in either direction had occurred, or the instrument sustained injury requiring repair by the manufacturer. RESULTS: One hundred nine flexible ureteroscopic procedures (average 27.5 procedures per instrument; range 19 to 34) were performed with the four new flexible ureteroscopes before being sent for repair. Adjuncts to reduce scope damage during these procedures were the use of the ureteral access sheath (n = 109), nitinol devices allowing lower pole stone retrieval (n = 27), and the 200-microm holmium laser fiber for stone fragmentation, tumor ablation, and incision of ureteropelvic junction/ureteral stenoses (n = 91). The average number of passes until more than 20 optical fibers were broken was 15.3 (range 12 to 20), until more than a 25 degrees loss of deflection occurred was 50.3 (range 42 to 66), or until the scope required repair was 66.7 (range 46 to 82). CONCLUSIONS: Flexible ureteroscopy will be used increasingly to manage upper urinary tract pathologic findings. Historically, the number of procedures performed before a flexible ureteroscope requires repair averaged 6 to 15. By incorporating the new ureteroscopic accessories, such as nitinol devices, a ureteral access sheath, and the 200-microm holmium laser fiber into common practice, one can reduce the strain on these fragile 7.5F endoscopes, thereby maximizing their longevity.
Equipment Failure↗
A stimulus generating system for studying wind sensation in the American cockroach.
A novel system for the generation and measurement of a two dimensional wind stimulus is proposed and described. This system was used to investigate the wind sensation of the American cockroach. The new aspects of this system are (a) a pair of computer driven wind tunnels that are shown to produce non-turbulent flows and (b) a novel fiber optic wind detector that measures both amplitude and direction of the wind. Winds can be produced and measured in behaviorally relevant frequency and amplitude ranges without perturbing the airflow. The combination of both the wind generation system and wind detector makes the system very flexible and allows the generation of stimuli with any given spectrum. The two dimensional wind stimulus is shown to be very reproducible. The wind detector is independent of the wind generation system so it can be used for measuring natural winds as well. Experimental data obtained on the cockroach are presented.
Air Movements↗
Measurement of some small-molecule and peptide neurotransmitters in-vitro using a fiber-optic probe with pulsed ultraviolet resonance Raman spectroscopy.
Many techniques have been developed to investigate the chemistry associated with brain activity. These techniques generally fall into two categories: fast techniques with species-limited sensitivity; and generally slower techniques with broader species sensitivity. Therefore, a need exists for a fast, minimally invasive technique that is sensitive to a wide array of biologically relevant compounds in order to measure chemical brain events in real time. The work presented here describes the development of a novel spectroscopic neurotransmitter probe for the rapid and simultaneous detection of a variety of neurotransmitters. A fiber-optic-linked Raman and tunable ultraviolet resonance Raman system was assembled with custom designed optical fiber probes. Using this system, the ultraviolet resonance Raman spectra of some small-molecule and peptide neurotransmitters were measured in-vitro with a fiber-optic probe and are reported here for the first time. The probe has furthermore been used to measure neurotransmitter secretions obtained from depolarized rat pheochromocytoma (PC12) cells. These results demonstrate the general utility of this approach which, due to the fiber-optic implementation, could potentially also be applied to in-vivo neurotransmitter determinations.
Acetylcholine↗
Acoustic standing-wave enhancement of a fiber-optic Salmonella biosensor.
An enhanced fluorescent fiber-optic biosensor system using ultrasonic concentration of particles and cells has been developed and applied in the detection of Salmonella typhimurium. A biosensor test chamber also serves as an ultrasonic standing-wave cell that allows microspheres or cells to be concentrated in parallel layers or in a column along the axis of the cell. A fiber probe along the axis delivers laser excitation to fluorescent-labeled antibodies of Salmonella and collects the fluorescent signal. The labeled-antibodies themselves do not respond to the ultrasound, but, when attached to Salmonella cells, the Salmonella-antibody complexes can be moved acoustically to the axis of the cell, increasing the fluorescent signal. In a second, more robust, type of immunoassay, the Salmonella-labeled-antibody complexes attach to unlabeled antibodies that have been immobilized on the surface of polystyrene microspheres. This entire structure can be manipulated acoustically and the increase in the fluorescent signal, which can be an order of magnitude, indicates the presence of Salmonella.
Biosensing Techniques↗
Evaluation of a fiber optic immunosensor for quantitating cocaine in coca leaf extracts.
A fiber optic evanescent fluoroimmunosensor was used to rapidly detect and quantitate coca alkaloids as cocaine equivalents in leaf extracts of five Erythroxylum species. A monoclonal antibody (mAb) made against benzoylecgonine (BE), a major metabolite of cocaine, was immobilized covalently on quartz fibers and used as the biological sensing element in the portable fluorometer. Benzoylecgonine-fluorescein (BE-FL) was used as the optical signal generator when it bound to the fiber. If present, cocaine competed for the mAb and interfered with the binding of BE-FL, thereby reducing the fluorescence transmitted by the fiber. Calibration curves were prepared by measuring (over 30 s) the rates of fluorescence increase in the absence, or presence of cocaine. Ethanol or acid extracts of dry coca leaves were assayed by this fiber optic biosensor, gas chromatography and a fluorescent polarization immune assay. Biosensor values of cocaine content of leaves from five Erythroxylum species were not significantly different from gas chromatography values, but had higher variance. The biosensor assay was rapid and did not require cleanup of the crude leaf extracts. Cocaine in acid extracts was reduced significantly after 4 weeks at 23 degrees C and after 3 weeks at 37 degrees C. Fibers (mAb-coated), stored at 37 degrees C in phosphate-buffered solution (0.02% NaN3), gave stable responses for 14 days.
Biosensing Techniques↗
Detecting staphylococcal enterotoxin B using an automated fiber optic biosensor.
The Man-portable Analyte Identification System (MANTIS), the first fully automated, self-contained, portable fiber optic biosensor, was utilized for the detection of Staphylococcal Enterotoxin B (SEB), a bacterial toxin produced by Staphylococcus aureus that commonly causes food poisoning. Because of its remarkable toxicity and stability, SEB is considered a prime threat as a biological weapon of mass destruction. The assay for SEB was used to evaluate the MANTIS' ability to function in the presence of various environmental interferents. The sensor could reliably detect SEB spiked into liquid samples containing a variety of smoke particles. However, substantial interference occurred when SEB was mixed into matrices capable of adsorbing SEB, such as 1% solutions of clay, topsoil, or pollen. Of equal importance, none of the interferents produced false positives in the MANTIS. The MANTIS demonstrated the capability to perform simultaneous immunoassays rapidly in the field with little or no user intervention.
Biosensing Techniques↗
Fiber optic sensor for Ca2+ based on an induced change in the conformation of the protein calmodulin.
A fiber optic sensor that exploits the natural selectivity of the Ca(2+)-binding protein calmodulin (CaM) is described. In this sensor, a dialysis membrane is used to entrap a fluorescein-labeled CaM (F-CaM) solution at the common end of a bifurcated fiber optic bundle. Ca2+ ions in a sample solution can diffuse through the membrane and bind to the F-CaM. Upon binding with Ca2+, CaM undergoes a conformational change that induces a change in the fluorescence of the attached fluorescein tag. This change in fluorescence can be related to the concentration of Ca2+ in the sample solution. The detection limit for the sensor is 5 x 10(-8) M Ca2+. The sensor has no interference by Mg2+ at concentrations as high as 10(-2) M.
Animals↗
Measurement of free phenytoin in blood with a self-contained fiber-optic immunosensor.
We describe the measurement of the anticonvulsant drug phenytoin (5,5-diphenylhydantoin) in human blood and plasma using a self-contained fiber-optic immunosensor which gave a reversible response to changes in concentration. No regenerative treatment of the immunosensor was required between measurements. The analytical signal depended on the degree of energy transfer from B-phycoerythrin labeled with phenytoin to Texas Red labeled anti-phenytoin antibody. Dextran 70K was added to the reagent system to equalize the oncotic pressure across the encapsulation membrane. A gas chromatography reference method was used to measure free drug concentrations. Regression analysis for plasma samples gave the relationship (sensor) = 1.02 (reference) + 0.07 microM; Syx = 1.00 microM; r = 0.953; sensor mean 4.45 microM; reference mean 4.31 microM. Sensor performance in plasma and whole blood was essentially equivalent. We demonstrate the feasibility of measuring free phenytoin directly in blood and suggest that the sensor design is generally applicable for the measurement of other haptens in blood.
Biosensing Techniques↗
Fiber-optic probe for kinetic determination of enzyme activities.
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Enzymes↗
Single fiber-optic fluorescence enzyme-based sensor.
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Enzymes, Immobilized↗
Fiber-optic biosensors based on the fluorometric detection of reduced nicotinamide adenine dinucleotide.
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Fiber Optic Technology↗
Regenerable fiber-optic-based immunosensor.
An immunosensor is described that is based on fluorescently labeled F(ab') anti-human serum albumin antibody fragments covalently immobilized to the distal end of a fiber-optic probe. When human serum albumin is present, it is bound to the sensor and shields the fluorescent label from the solvent water, and a significant increase in the label fluorescence results. The sensor can be regenerated by simply immersing the sensing tip in chaotropic media. Under these conditions the antigen-antibody complex is selectively disrupted without adversely affecting the sensor. In the present configuration, the same sensor can be recycled over 50 times before the immunosurface inactivates significantly. With proper storage the sensor can last for up to 4 months.
Electrodes↗
Feasibility of using liquid crystals for the development of molecularly selective fiber-optic chemical sensors.
A new type of fiber-optic chemical sensor has been developed for the determination and differentiation of geometric isomers. The operation of the sensor is based upon the molecular-geometric-selective absorption of polynuclear aromatic hydrocarbons (PAH) on a liquid crystal. The selective interaction of a PAH with a liquid-crystal substrate causes quenching of the liquid-crystal fluorescence. Detection limits of such a device for PAH compounds approach 10(-10) mol/cm3; the sensor response time is about 2 min. Because the sensor is based upon physical absorption, it is reusable and reversible.
Fiber Optic Technology↗