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Biomedical subjects

B Jean

Publications and source records attributed to B Jean.

At least 55 records · Page 3Linked to original sources
PubMed1989

[CO2 laser vaporization of papilloma of the conjunctiva and eyelids].

In irradiated tissue, the farinfrared CO2 laser generates high temperatures of around 400 degrees C. Thermal damage can occur at the borders of the area being treated, but there are good hemostatic properties and thermal sterilization of the irradiated tissue. Photovaporization of papillomas has been occasionally proposed to achieve thermal inactivation of papilloma viruses and reduce the recurrence rates. Seventy-five cases of recurrent squamous papilloma were vaporized with a CO2 laser and followed-up for over 2 years. Only 2 recurrences were observed (20% have been reported after surgical excision). The procedure is quick, safe, easy to perform and well accepted by the patient. Good hemostatic properties, lack of cicatrication, and excellent cosmetic results are further advantages. Histological examination may be limited by thermal tissue damage.

Adult↗
PubMed1987

[A tracker for ophthalmology].

Real-time tracking of eye movements offers a solution to various problems in ophthalmology. Different types of image analysis and processing techniques is discussed and an advanced pattern recognition eye-tracking system has been developed; it can track a retinal target (in real time) under conditions typical for ophthalmologic examination and therapy. The sensor is a modified low-light video fundus camera. An example illustrates how a retinal target is automatically found again when it has been "lost".

Eye Movements↗
PubMed1987

[Malaria tropica with macular hemorrhage].

We describe the case of a 33-year-old patient with recurrent tropical malaria, comma and isolated subpigmentepithelial macular hemorrhage causing irreversible visual loss. This strictly subpigmentepithelial macular hemorrhage is the second case described. Its importance lies in the fact that the typical plugging of vessels in acute tropical malaria is also observed in the choroid. Current knowledge about occlusion during acute malaria falciparum infection and hypotheses concerning its cause are reviewed in relation to retinal and choroidal pathology.

Adult↗
PubMed1987

[Simultaneous fluo-angioscope. Image superposition for macular photocoagulation].

A new, compact optical instrument developed in clinical work is presented and its optical properties are discussed: it allows simultaneous viewing of a patient's fundus and its fluorescein angiography. Both stereo and mono angiography can be superimposed in the slit lamp in a 1-to-1 juxtaposition of fundus topography and angiogram. In this way very precise transfer of angiographical data is possible. Safety during laser coagulation is increased, and the size of iatrogenic scotomas is thus reduced. The instrument is described, and image superimposition illustrated with clinical examples.

Fluorescein Angiography↗
PubMed1986

[Simultaneous fluo-angioscope: a method for laser treatment close to the macula].

The Simultaneous Fluo-Angioscope is a compact optical device developed in clinical work as ancillary equipment for laser slit lamps. Both binocular and stereoscopic fluorescein angiograms can be directly overlaid onto the patient's fundus in the slit lamp in a 1-to-1 juxtaposition of angiographic data and fundus topography. In this way precise paramacular laser coagulation is achievable with a minimum of scotoma. The overlaying of earlier photos onto the present fundus also makes objective diagnosis of tumors, vessels, and other pathologically significant areas possible.

Fluorescein Angiography↗
PubMed1980

A semi-automated rapid and sensitive microcytotoxicity assay for antibody-mediated cytolysis.

This technique used a Coulter counter to enumerate the target cells remaining after partial lysis with antibody and complement, followed by the destruction of the lysed cells with pronase. Results obtained by this method are compared with those from conventional dye exclusion tests where the final enzymatic step is omitted. Comparisons were made with an anti-Thy-1.2 serum, a monoclonal anti-Thy-1.2 preparation and an anti-H-2k serum. In all cases the semi-automated test gave better results than the dye exclusion test and proved to be highly sensitive and reproducible.

Animals↗
PubMed1980

Investigations on female Onchocerca volvulus for the evaluation of drug trials.

Females of O. volvulus show several typical morphological alterations during their ontogenesis. In order not to attribute such natural findings to the efficacy of drugs in drug trials female worms isolated from untreated patients in Liberia and Togo were examined by light microscopy. Local incrustations could be found regularly on the surface of the female parasite. Different inclusions are described which could often be found. They partially lead to degeneration and calcification. For the evaluation of ovocidal or embryocidal efficacy of drugs the developmental stages of 290 untreated female worms were quantitatively assessed, normal and pathologically altered forms were distinguished. Embryos were obviously not produced continuously but in intervalls of unknown length and frequency. Two third of the females contained embryos and microfilariae, one third showed eggs only or had empty uteri. The number of the developmental stages per female varied considerably. On the average more than 200,000 stages per female were found.

Animals↗
PubMedDate not supplied

PMMA cementoplasty in symptomatic metastatic lesions of the S1 vertebral body.

We describe a lateral transiliac direct puncture approach to the S1 vertebral body for polymethylmethacrylate (PMMA) cementoplasty of painful metastatic lesions. This approach was performed using a 15-cm-long trocar needle with 3-mm outer diameter, introduced under general anesthesia and fluoroscopic control. A lateral projection was used to center the needle just in front of the spinal canal and subjacent to the superior plate of the S1 vertebral body. Needle progression was controlled using anteroposterior and lateral fluoroscopic projections alternately with a needle course parallel to an axial plane, avoiding conflict with the S1 foramen. After needle tip placement in the center of the S1 vertebral body, diluted PMMA with a setting time of 8 min was delivered. Ipsilateral lesions of the lateral sacral compartment were filled with the same needle by stepwise withdrawal and continuous PMMA injection.

Bone Cements↗
PubMedDate not supplied

Bronchial aneurysms mimicking aortic aneurysms: endovascular treatment in two patients.

Bronchial artery dilatation and aneurysm formation is a potential complication of local inflammation, especially in bronchiectasis. When the bronchial artery has an ectopic origin from the inferior segment of the aortic arch, aneurysms may mimick aortic aneurysms. Despite this particular location, endovascular treatment is possible. We report two such aneurysms that were successfully embolized with steel coils.

Aneurysm↗
PubMedDate not supplied

Thermal collateral damage in porcine corneas after photoablation with free electron laser.

BACKGROUND: The study describes a quantitative and systematic investigation of the collateral thermal damage during infrared photoablation as a function of wavelength between 2.7 and 6.7 microns. METHODS: Using the tunable Free Electron Laser at Vanderbilt University, Nashville, Tenn, 60 freshly removed porcine cadaver eyes were irradiated at wavelengths between 2.7 and 6.7 microns, at a fluence of 1.3 J/cm2. For wavelengths where no photoablation occurred, fluence was increased to 3.5 J/cm2; pulse length (macropulse) was 4 microseconds, consisting of a train of micropulses (pulse duration 2 ps at a 2.9 GHz repetition rate). The corneal buttons were removed and stained with hematoxylin and eosin (H&E) and analyzed by histologic micrometry. RESULTS: Two thermal damage zones in the remaining tissue were observed: zone 1 showed superficial carbonization and measured between 2 and 4 microns; beyond, the eosinophilic zone 2 measured between 10 and 100 microns. The extent of zone 2 was inversely related to the absorption spectra of the cornea; it was minimal at the 3- and 6-micrometer water absorption bands and maximal at minimal target absorption. CONCLUSION: The results correlated well with a model of the ablation process. The study provides a systematic and predictive element for the determination of collateral thermal adverse effects; it does not yet include pulse length variation as a determining factor.

Animals↗
PubMedDate not supplied

Laser thermal keratoplasty using a continuous wave diode laser.

BACKGROUND: Laser thermal keratoplasty is currently performed with a pulsed Ho:YAG laser at 2.07 microns wavelength. Long-term stability depends critically on the coagulation depth of each cone and thus on emission wavelength (absorption in corneal tissue) and focusing, all contributing to controlled stable collagen shrinkage. To achieve this, a temperature range of 65 degrees to 90 degrees C is needed. A continuous wave laser source meets the coagulation requirements more effectively by avoiding tissue cooling by thermal diffusion as well as the peak temperatures of pulsed lasers, which counteracts the intended central corneal steepening. METHODS: A continuous wave diode laser was developed, emitting at 1.885 microns with a maximal energy output of 450 mW. In a contact focusing application, the absorption depth in water as a function of wavelength was measured. Using laser parameters, comparable to those used for a pulsed Ho:YAG laser in contact mode, coagulation spots in human cornea were applied for the continuous wave diode laser. RESULTS: The macroscopic and microscopic effects of the diode laser coagulation on corneas in vitro and in situ were comparable to those of the Ho:YAG laser, if a comparable amount of total energy per spot was applied. CONCLUSION: Due to better optimized laser-collagen interaction, higher corrections and more stable clinical refractive effects appear achievable using the continuous wave diode laser.

Cadaver↗
PubMedDate not supplied

Silicon cast method for quantification of photoablation.

BACKGROUND: Topometry and measurement of photoablation patterns are key questions for keratorefractive photoablation. Ablation rates have been determined previously by either tissue perforation or by micrometry performed on histologic sections. METHODS: A three-dimensional cast of cornea after irradiation was made by using a two-component silicon gel that polymerizes within minutes, thus preserving the corneal topography immediately after photoablation. Polymerization is athermal and nontoxic. The resulting silicon blocks were cut perpendicularly to the anterior surface and measured by calibrated light microscopy. RESULTS: The silicon surface is extremely smooth and the accuracy of the cast is better than 0.25 micron. Reproducibility and long-term stability were demonstrated for casts of photoablated polymethylmethacrylate. Thus, ablation rates and profile, volumetry, and topometry can be determined following laser ablation. The method has been applied for 193-nanometer excimer laser in vitro irradiation of the human cornea. Ablation rates in Bowman's layer and stroma for various radiant energies and distinct pulse numbers were found to be in agreement with published data, and an incubation effect for the first laser pulses could be demonstrated. CONCLUSIONS: The method is nondestructive, accurate, inexpensive, practical, and reduces requirements for laboratory animals.

Animals↗