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Biomedical subjects

S Mordon

Publications and source records attributed to S Mordon.

At least 73 records · Page 4Linked to original sources
PubMed1992

[Proximal tubal recanalization by endoluminal laser probe. I. Anatomic results in the female rat].

To evaluate the cicatrization of the uterine horn after the recanalization by endoluminal laser probe, 50 white female rats of Wistar's race have been separated into two groups. The group 1 (nb = 10) had for aim to validated the procedure of obstruction. In group 2 (nb = 40), we performed the recanalization six weeks after the obstruction. Histologic samples were obtained 48 hours, 3 weeks and 6 weeks after treatment. In group 1, we found a complete obstruction in 70% of the cases, and a tight stenosis in 30% of the cases. In group 2, at 48 hour's control after the treatment by laser, we found a drill hole with a blackened look without parietal sequel in 80% of the cases. At 6 week's control, we found a normal lumen with a regeneration of the epithelioma in 85% of the cases. For energy deposition under 30 Joules, we found good results in 95% of the cases. Above 30 Joules, we always found bad results (5 cases on 5).

Animals↗
PubMed1992

[Proximal tubular recanalization by endoluminal laser. II. Functional results in the female rabbit].

To evaluate the function of the fallopian tube after a recanalization by endoluminal laser probe, 34 mature female New Zealand white rabbits have been separated into two groups. The group 1 (nb = 12) had for aim to validate the procedure of obstruction. In group 2 (nb = 22), we performed the recanalization six weeks after the obstruction. The female rabbits underwent a fertilization six weeks after the laser treatment. The results have been appreciated by the ratio nidation/ovulation. In group 1, we valided the procedure of obstruction. In group 2 twelve rabbits on thirteen have been fecundated in the treated tube.

Animals↗
PubMed1991

[Use of frequency doubled Nd-YAG laser and automatic scanning in the treatment of portwine hemangioma].

The authors report their experience in the treatment of portwine stains by means of two recent improvements. The first improvement concerns the use of frequency doubled Nd-YAG laser which emits at 532 nanometres. This wave-length corresponds to an absorption peak of haemoglobin and is therefore more selectively absorbed by haemangiomatous tissue. This helps to explain the better clinical results obtained and the elimination of the other effects classically induced by argon laser, with complete preservation of the healthy, non-angiomatous skin as well as skin and scalp hair. Treatment is consequently facilitated, as illustrated by a series of 79 patients who received a total of 92 treatment sessions over a period of 14 months. The second improvement consists of the addition of an automat which allows the beam to be used continuously with scanning of adjacent bands. This automat not only allows a very homogeneous treatment by eliminating all of the errors associated with manual scanning, but can also be used to treat large portwine stains in a single session instead of the multiple sessions required previously. An interval of 5 to 6 months should be respected before treating the residual part of the portwine stain situated more deeply in the dermis, which should be considered to be a new portwine stain. The combination of these two apparatuses allows fluences (fluence is the product of the power selected by the exposure time per unit area) of only 8 to 15 joules/cm2 due to the dynamics of the treatment in contrast with other static modalities which require higher fluences.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

[Development and evaluation of a laser catheter with tip fiberoptic for coronary angioplasty].

A fiber-optic tip catheter has been developed for treating coronary and peripheral atherosclerosis percutaneously. The catheter is coupled to an ionised Argon laser emitting at an optical power of 1 to 7 Watts. It is designed to follow a guide wire and to perform tissue ablation by a new concept combining the effects of central vaporisation and peripheral thermal remodelling of the obstructed artery. This mode of function should considerably reduce the risks of false route previously encountered with laser angioplasty. The optical and thermic properties of the catheter prototypes were determined by physical methods. These experiments showed that the temperature of the metallic component of the catheter tip did not exceed 30 degrees C at a continuous power of 6 laser Watts when the flush was functioning. It attained 400 degrees C in the absence of the flush. The performances of the catheter were then tested in a number of in vitro experiments. First of all, the catheter tip was placed perpendicularly to atheromatous cadaver aortae to study the effect of vaporisation with respect to the laser power. The threshold of vaporisation was 1 Watt (irradiance: 1100 Watts/cm2). The catheter was then introduced into plastic tubes obstructed by atheromatous plaques. This experiment demonstrated the mechanical solidity of the catheter and its flexibility in difficult operating conditions: diameter 2mm, 45 degrees angles, irregular calcified plaques. It also showed that the optimal safety-efficacy laser power was 3 laser Watts and that the exposure times varied with respect to the nature of the plaques tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1990

Effects of 1.32-micron Nd-YAG laser on brain thermal and histological experimental data.

Considering that the 1.32-microns Nd-YAG laser should have physicothermal properties close to those of the CO2 laser, a series of experiments were conducted on rat cortex (N = 51). Three laser wavelengths were compared: CO2 laser (10.6 microns), 1.06-microns Nd-YAG, and 1.32-microns Nd-YAG lasers. For each shot, temperature measurements were recorded with an infrared thermographic videocamera. The digitized signals were figured as thermal profiles and temperature developments. Ninety-five shots were correctly studied and analyzed: CO2, N = 29; 1.06-microns Nd-YAG, N = 20; 1.32-microns Nd-YAG, N = 46. The histological lesions produced by these three lasers were compared on animals killed 24 hours (N = 20), 8 days (N = 20), and 30 days (N = 5) after the laser impacts. For equivalent densities of energy, the depth of cortical necrosis was comparable for the CO2 laser (200-250 microns) and the 1.32-microns Nd-YAG laser (210-260 microns) whatever the date of death; the 1.06-microns Nd-YAG laser shots were responsible for much more important damage (400-550 microns). Because of its important absorption in water and nervous tissue, the authors consider the 1.32-microns Nd-YAG laser most suitable for neurosurgery, particularly because it is conducted through optic fibers, and therefore is easy to handle during neurosurgical procedures.

Animals↗
PubMed1990

The use of 1.32 Nd:YAG laser in neurosurgery: experimental data and clinical experience from 70 patients.

The authors present their experience with the 1.32 mum Nd:YAG laser in neurosurgical procedures. In a first step, they conducted experiments on rat cortex. The thermic data and histologic results confirmed that the 1.32 Nd:YAG laser has physical properties quite close to the CO2 laser. Furthermore, the fact that the 1.32 mum wavelength can be conducted through optic fibers makes it well adapted to neurosurgery. The authors present experimental data (50 rats) and comment on their surgical experience with such a wavelength (70 patients). In the future, this laser should see its indications broadened in conventional neurosurgical procedures as well as in endoscopic and stereotactic neurosurgery.

Animals↗
PubMed1990

Hexascan: a new robotized scanning laser handpiece.

A variety of treatment techniques are used with both argon and tunable dye lasers. Each method has its unique advantages: however, all appear to share common limitations such as poor reproducibility, lack of homogeneous energy delivery, and inability to treat rapidly large cutaneous vascular disorders such as port-wine stains. These problems have recently been addressed with a new scanning device designed to automate or speed treatment and provide improved consistency in cosmetic results. Hexascan is a computerized, automated scanning device that allows for the rapid and easily reproducible treatment of large areas of skin using either the dye or argon laser. The scanning pattern is designed to promote uniform energy fluence and minimize unwanted thermal damage to nontarget tissue. Clinical trials using Hexascan with 577 nm and 585 nm wavelengths have shown good results with cutaneous vascular disorders. Utilizing blue-green argon wavelengths, markedly reduced scarring has been observed compared to traditional argon techniques. Use with 514 nm green only argon light has successfully removed a variety of benign brown pigmented cutaneous lesions.

Adolescent↗
PubMed1989

[The 1.320 micron Nd-YAG laser. Experimental study of a new wavelength adapted to neurosurgery].

The authors present a new laser wavelength for neurosurgery: the 1.32 micron Nd-YAG laser. Schematically, it combines the advantages of both the 1.06 micron Nd-YAG laser and the CO2 laser. As for nervous tissue it has the same physico-thermal properties as the CO2 laser: an important absorption and little thermal diffusion. Like the 1.06 Nd-YAG laser, the 1.32 Nd-YAG has very good maneuverability, because its beam is conducted through optical fibers. Experimental studies have been made on rats. They consisted of comparison between the thermal effects and the consequent histological lesions of three lasers: 1.32 micron Nd-YAG, 1.06 micron Nd-YAG, CO2. 145 impacts on the cortex of 45 rats have been studied. Each shot was registered with an infrared camera, measuring the cortex surface temperature around the impact. The signals were digitalized; they allowed us to obtain a numerical image and the profile of temperature for each shot, as well as the development of temperature of each point of the profile. These results have been correlated with the histological data. It appears that for equivalent efficient outputs, the cortical lesions, 8 days after the shots, were similar for the 1.32 Nd-YAG laser and the CO2 laser. For instance, the depth of the coagulation necrosis varied from 200 to 250 microns after CO2 laser impacts (P = 3W; t = 0 05s; Fluence = 5 Joules/cm2), and from 210 to 260 microns after 1.32 Nd-YAG laser impacts (P = 5-14W; t = 0.4s; F = 50-170 J/cm2).(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum Silicates↗
PubMed1988

Robotized scanning laser handpiece for the treatment of port wine stains and other angiodysplasias.

Port wine stains are currently treated by the argon laser with the "point-by-point" technique, or the "painting technique." In both cases, the quality of the results depends greatly on the dermatologist's experience. Furthermore, the first technique is slow, and the second is painful and requires anesthesia. Therefore, we have decided to design a robotized system with the following specifications: easy, fast, non-painful treatment giving a homogeneous and reproducible blanching. The system is made of a handpiece with the scanning mechanism and a control box with the microprocessor. The system is independent of the laser (no electrical connection) and has its own power meter. The deposit of energy was optimized in function of heat diffusion in the skin. Over a 12-month period, 123 patients were treated with the robotized handpiece. The treatment modalities and the results conformed to the above-mentioned specifications. Hypertrophic scars were not reported. Therefore, we think that this system will be an interesting tool for the laser treatment of port wine stains and other cutaneous angiodysplasias.

Adolescent↗
PubMed1988

[A new method of laser angioplasty by contact sapphire: preliminary results. Apropos of 20 cases].

We report our first 20 cases of peripheral laser angioplasty using an optic fibre with contact sapphire tip. The equipment included a teflon catheter on which was screwed a round sapphire 2.2 mm in diameter. A 600 microns optic fibre connected to a Nd-Yag laser instrument was introduced into the catheter and placed in contact with the sapphire. Twenty patients underwent recanalization of femoral or popliteal arteries occluded on a length of 5 to 45 cm. The sapphire-tipped catheter was introduced by the Seldinger technique up to the site of occlusion. The 15 watt laser emission was set at intervals of one second. Sixteen out of the 20 occluded arteries were recanalized. Among the 4 failures, 3 were due to perforation and 1 to intraparietal progression. Angioplasty was performed with laser alone in 3 cases and with laser completed by balloon catheter in 13 cases. The minimum diameter of the laser-induced channel was 2 mm and was significantly increased (3.8 mm) by complementary balloon dilatation. In the 3 patients who underwent laser angioplasty alone, no noticeable improvement in distal blood flow was demonstrated by doppler velocimetry, and reocclusion occurred either soon afterwards (n = 2) or later (n = 1). Midterm results were much better in patients who had had additional balloon dilatation: early (3rd day) or late (2 months) reocclusion took place in only 3 patients. In the remaining 10 patients, followed up for periods of 1 week to 18 months (mean: 6 months), clinical improvement and recanalization were maintained.

Angioplasty, Balloon↗
PubMed1987

Thermal effects of lasers on dental tissues.

The thermal effects of Nd:YAG, argon, and CO2 laser beams are observed on enamel, dentin, and dental pulp by means of computerized infrared thermography and thermocouple. This study shows that the Nd:YAG laser beam deeply diffuses through the enamel and dentin to the pulp. The argon laser effects are inconsistent depending on whether the enamel surface is cleaned, but after cleaning, the superficial and deep temperatures are low. With the CO2 laser, the enamel and dentin surfaces reach very high temperatures, but only low temperatures are measured in the pulp chamber.

Body Temperature↗
PubMedDate not supplied

In vivo behaviour of long-circulating liposomes in blood vessels in hamster inflammation and septic shock models-use of intravital fluorescence microscopy.

This study aimed to observe liposome uptake by leukocytes in vivo. The study was performed on skin by using a dorsal skin-fold chamber implanted in golden hamsters using intravital microscopy. 5 and 6-CF-encapsulated polyethylene glycolated liposomes were injected intravenously. The skin microcirculation was observed with an intravital Eclipse E800 Nikon microscope (using x40, x80 magnification) fitted with a Xenon light source and an epifluorescence assembly (excitation, 470 nm, FWHM 40 nm; emission, 540 nm, FWHM 40 nm). An ultra-high sensitivity videocamera mounted on the microscope projected the image onto a monitor, and the images (720 x 576 pixels) were recorded for playback analysis with a digital video cassette recorder. An acute inflammatory response was obtained by removing one complete layer of skin and the underlying fascia and avascular tissue on the opposing side of the flap corresponding to an area equivalent to the window aperture. Using this model and set-up, leukocyte rolling and adhesion were easily observed and the entry of PEGylated liposomes into hamster blood leukocytes was studied for a period of 6 h. PEGylated liposomes were clearly identified alone inside the blood flow and inside the leukocytes as soon as the inflammatory reaction appeared. This study shows for the first time that blood leukocytes in their natural milieu of whole blood are capable of interacting with, and taking up, liposomes. This observation is in accordance with previous in vitro studies.

Animals↗
PubMedDate not supplied

Fluorescence properties and metabolic features of indocyanine green (ICG) as related to angiography.

Indocyanine green (ICG) is a fluorescent dye that has been used for the imaging of retinal and choroidal vasculatures for more than 30 years. Its high molecular weight, specific metabolic features, and its infrared spectra make the specificity of the images obtained with this dye in ophthalmology. The focus of this paper is to review the basic properties of ICG and to show how some clinical features related to basic properties also depend on the instrumentation used to perform ICG angiography. Indocyanine green has a complex molecular structure that leads to amphiphilic properties, that is, both hydrophilic and lipophilic properties. These properties explain that a specific interaction with phospholipids influences the emission spectrum and the fluorescence yield of ICG. The composition of cell membranes mainly composed of phospholipid bilayers is consistent with a binding and/or a diffusion of ICG molecules observed on angiograms. Likewise, ICG can bind to the lipid component of miliary drusen, explaining their hyperfluorescence. A knowledge of ICG basic properties and interactions may allow a better understanding of angiograms performed with this dye.

Absorption↗
PubMedDate not supplied

Fluorescence imaging method for in vivo pH monitoring during liposomes uptake in rat liver using a pH-sensitive fluorescent dye.

Liposomes are known to be taken up by the liver cells after intravenous injection. Among the few techniques available to follow this process in vivo are perturbed angular correlation spectroscopy, nuclear magnetic resonance spectroscopy, and scintigraphy. The study of the intracellular pathways and liposomal localization in the different liver cells requires sacrifice of the animals, cells separation, and electronic microscopy. In the acidic intracellular compartments, the in situ rate of release of liposomes remains poorly understood. We present a new method to follow the in situ and in vivo uptake of liposomes using a fluorescent pH-sensitive probe 5,6-carboxyfluorescein (5,6-CF). 5,6-CF is encapsulated in liposomes at high concentration (100 mM) to quench its fluorescence. After laparotomy, liposomes are injected into the penile vein of Wistar rats. Fluorescence images of the liver and the skin are recorded during 90 min and the fluorescence intensity ratio is calculated. Ratio kinetics show different profiles depending on the liposomal formulation. The calculated intracellular liver pH values are, respectively, 4.5 to 5.0 and 6.0 to 6.5 for DSPC/chol and DMPC liposomes. After sacrifice and flush with a cold saline solution, the pH of the intracellular site of the liver (ex vivo) is found to be 4.5 to 5.0. This value can be explained by an uptake of liposomes by the liver cells and subsequent localization into the acidic compartment. An intracellular event such as dye release of a drug carrier (liposomes loaded with a fluorescent dye) can be monitored by pH fluorescence imaging and spectroscopy in vivo and in situ.

Animals↗
PubMedDate not supplied

[Value of fluorescein angiography in control of retinal thermal damage due to diode laser].

PURPOSE: To evaluate on an ocular ophthalmic model the interest of digitized fluorescein angiography for a control of laser induced thermal damage. METHOD: After anesthesia, retinal photocoagulation was performed on 6 rabbit eyes with a 810 nm diode laser (p = 100 to 400 mW, phi = 500 microns, 1s) (OcuLight, IRIS Medical Instruments Inc., USA). Fluorescein angiography was then performed with measurements of fluorescence intensity in the area of the laser exposures (CF-60UVi Canon-Europe, The Netherlands; OcuLab, Life Science Resources Ltd, England). RESULTS: Image analysis shows that the laser lesions stained progressively. For dosages up to 100 +/- 20 mW fluorescence intensity at the center of the laser spot could be modelized with: Icentrer = Imax [(1-e-alpha t)]-Ce beta t with alpha = 0.2 (s-1), beta = 0.46 (s-1); Imax 230 and C = 0.92. For dosages superiors to 200 +/- 20 mW the modelization was: Icenter = Imax [(1-e-alpha t)] with alpha = 0.2 (s-1 and Imax = 230. CONCLUSION: This study demonstrates that quantitative assessment of laser-induced damage to the retina is feasible using fluorescence imaging. The quantification of fluorescence staining in terms of both intensity and time can contribute to a better quantification of laser-induced damage.

Animals↗