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Biomedical subjects

A Katzir

Publications and source records attributed to A Katzir.

29 records · Page 2Linked to original sources
PubMed1989

Infrared fibers for radiometer thermometry in hypothermia and hyperthermia treatment.

Hypothermia is a condition which results from prolonged exposure to a cold environment. Rapid and efficient heating is needed to rewarm the patient from 32-35 degrees C to normal body temperature. Hyperthermia in cancer treatment involves heating malignant tumors to 42.5-43.0 degrees C for an extended period (e.g., 30 min) in an attempt to obtain remission. Microwave or radio frequency heating is often used for rewarming in hypothermia or for temperature elevation in hyperthermia treatment. One severe problem with such heating is the accurate measurement and control of temperature in the presence of a strong electromagnetic field. For this purpose, we have developed a fiberoptic radiometer system which is based on a nonmetallic, infrared fiber probe, which can operate either in contact or noncontact mode. In preliminary investigations, the radiometer worked well in a strong microwave or radiofrequency field, with an accuracy of +/- 0.5 degrees C. This fiberoptic thermometer was used to control the surface temperature of objects within +/- 2 degrees C.

Fiber Optic Technology↗
PubMed1988

Carbon dioxide laser effect on platelet function and surface ultrastructure in vitro.

Platelet aggregation may be an important factor in the feasibility of transcatheter laser angioplasty. The in vitro effects of increasing doses of CO2 laser irradiation on platelet number, function, and surface ultrastructure were examined. Results indicated a progressive dose-response reduction of both platelet number and function following laser irradiation. By scanning electron microscopy the irradiated platelets showed dose-related changes in pseudopods as well as progressive damage of the cell membrane.

Adult↗
PubMed1988

The use of carbon dioxide fiberoptic laser catheter for atrial septostomy.

The development of optical fibers capable of transmitting laser energy has encouraged the experimental use of laser irradiation for the treatment of acquired cardiovascular disorders. One of the key questions is which combination of laser source, energy parameters, and transmitting fiberoptic would be best suited for intravascular use. In most experiments argon, neodymium-YAG, and excimer lasers, coupled to suitable optical fibers, have been used. We now describe the use of a carbon dioxide fiberoptic laser catheter for the creation of an atrial septal defect. Silver halide infrared transmitting fibers were inserted into standard 6 French cardiovascular catheters. This laser catheter system, capable of transmitting several watts of pulsed CO2 laser energy, was initially used to create atrial septal defects in isolated dog hearts to determine the best energy parameters. Atrial septostomy was later performed successfully in four of five anesthetized dogs. The thermal damage extended 50 to 60 micron beyond the "holes" created by the laser irradiation in the interatrial septum. Thus, pulsed CO2 laser irradiation, delivered through optical fibers, can create an atrial septal defect.

Animals↗
PubMed1987

Fourier transform infrared spectra of aqueous protein mixtures using a novel attenuated total internal reflectance cell with infrared fibers.

A specially designed cell containing a silver halide (AgBr:AgCl) infrared fiber allows convenient and reproducible loading of viscous protein solutions and suspensions. Attenuated total internal reflectance measurements using an FTIR spectrometer were made for bovine serum albumin-water past. Dynamic changes in the protein films are readily followed, a technique which should be generally useful. A band assigned to a secondary structural feature, the alpha-helix, is similar in intensity to that reported (T.M. Fong, M.G. McNamee, submitted for publication).

Bromides↗
PubMed1986

The effects of varying lengths and powers of CO2 laser pulses transmitted through an optical fiber on atherosclerotic plaques.

We have studied the changes induced in atherosclerotic arteries by a CO2 laser beam delivered through a silver halide optical fiber. We found that the crater depth and diameter correlate with the total energy delivered and with the mode of delivery. Short-duration high-power pulses caused shallower and narrower craters and less damage to the arterial wall compared to the same energy delivered as low-power pulses of long duration. Thus, high-power pulses for short periods may be an effective and safe procedure for evaporization of atherosclerotic plaques.

Arteriosclerosis↗
PubMed1976

Responses of Phycomyces indicating optical excitation of the lowest triplet state of riboflavin.

Phototropic and light growth responses of the sporangiophore of Phycomyces have been elicited using tunable laser stimulation from 575 to 630 nm. The growth response shows additional components of the action spectrum with a sharp peak at 595 nm, a sharp cut-off at 585 nm, and a tail extending beyond 630 nm. The integral over the electronic transition (f-value) is 1.5 X 10(-9) times that at 455 nm. These parameters indicate a direct transition from the ground state to the lowest triplet state of riboflavin.

Fungi↗
PubMedDate not supplied

Subjective comparison of Nd:YAG, diode, and CO2 lasers for endoscopically guided inferior turbinate reduction surgery.

Lasers using different wavelengths and delivery systems have been used to reduce the inferior turbinate mass when hypertrophic inferior turbinates obstruct the nasal airway. Different laser systems produce different laser-tissue interactions. This study presents a comparison between three laser systems: CO2, Nd:YAG, and Diode lasers for inferior turbinate reduction surgery, all performed under endoscopic control. A total of 46 patients were randomized into three treatment groups and followed for more than 1 year. Subjective and objective data were collected. Subjective impressions of improved nasal airway was achieved in 41% (Diode), 47% (Nd:YAG) and 57% (CO2) and was not statistically significant. There was more postoperative bleeding in the CO2 laser group, with 3 patients requiring tamponade. The CO2 laser procedure also took longer to perform. These results failed to show a significant difference between the different lasers for inferior turbinate reduction. Overall, the results were not impressive.

Adult↗