PubMed Health⌕ Search

Biomedical subjects

D Fritsch

Publications and source records attributed to D Fritsch.

At least 19 recordsLinked to original sources
PubMed2004

Web-based tools for quantitative renal physiology.

We present the development strategy and present state of progress on an interactive website project for quantitative renal physiology: a) a quantitative kidney database (QKDB), and b) an interactive website presenting mathematical models covering the major aspects of renal physiology. QKDB will house data for quantitative evaluation of hypotheses of renal function, from the cellular, through the epithelial and tubular, to whole organ levels. It will thus facilitate comparisons among different species and under various experimental conditions. It will include especially: transport parameters, tubular concentrations and flow rates along the various nephron segments, and anatomical details, in human kidneys, in experimentally studied species, and in model epithelia, such as cultured cells and amphibian skin and urinary bladder. The modeling resource will provide an interactive user interface to a collection of published models at all levels of renal physiology, enabling non-modelers to exploit the models, altering key parameters according to hypotheses of their own and visualizing the simulation results, thus permitting quantitative exploration of new hypotheses. Implementation will be facilitated by translation of the models into a common markup language such as CellML (cell markup language) and SBML (systems biology markup language). There will thus be a modular separation of model descriptions from their numerical solution methods.

Animals↗
PubMed1992

[Unusual uses of liquid perfluorocarbons].

Since the use of low viscosity perfluorocarbon liquids by Chang in 1987, many applications in vitreoretinal surgery have become possible owing to their physical properties (density, viscosity and refraction index). Perfluorocarbon liquids are used exclusively when a vitrectomy is necessary. The main indications are drainage of subretinal fluid by peripheral dehiscence, to facilitate dissection of vitreo retinal proliferation, in retinal detachment by giant tear and in posterior lens dislocation. The authors report three cases illustrating two new indications for perfluorocarbon liquids. Confirming the presence or absence of a peripheral dehiscence in a total retinal detachment if vitrectomy is necessary, subretinal fluid is displaced and escapes via a possible dehiscence. Treatment of vitreretinal incarcerations in a sclerotomic orifice during a vitrectomy is simplified. Easier treatment of this complication is made possible by the injection of perfluorocarbon liquids into the "non-incarcerated" orifice. Despite the more frequent use of perfluorocarbon liquids in vitreoretinal surgery, the possible specific complications which may occur with these products mean that they should be used with caution.

Female↗
PubMed1991

Space charge effects in a kinestatic charge detector.

The effects of space charge in a kinestatic charge detector (KCD) were examined using computer solutions to Poisson's equation. The KCD is a strip-beam parallel-plate drift chamber used for digital radiography. It was assumed that there is negligible electron attachment, i.e. there are no negative ions formed. The ionization rate per mA as a function of x-ray interaction depth was calculated for a detector filled with xenon at 25.3 x 10(5) Pa. Solution of Thomson's equations gave the positive ion density at the cathode, also as a function of depth. Water filtration values ranging from 0 to 30 cm were used in order to estimate the range of ion density values expected in a clinical KCD. The case of steady-state x-ray illumination was simulated for ionization rates less than the zero field limit (above which space charge changes the polarity of the electric field). Line spread responses were found for varying ionization rates to show the effect of space charge due to electric field distortion on the spatial resolution performance in the drift direction. The effect of imaging ideal edges with a KCD was calculated and the expected output signal was plotted for densities up to the zero field limit. Space charge dependence on the selection of KCD design and operating parameters is discussed. Because of the dependence of the KCD drift-direction spatial resolution on the uniformity of the electric field, space charge effects impose an upper limit on the detector entrance exposure and define the dynamic range of the device.

Humans↗
PubMed1989

[Etiology of childhood visual impairment in 1989].

We studied the etiologies of visual impairment in the 171 children managed at the Alfred Peyrelongue Center, Ambarès France. This center is open to visually impaired children aged 3 to 20 years and free of significant motor or cognitive handicaps. Etiologies of visual impairment in the decreasing order of frequency were as follows: cataract (31 cases), tapetoretinal degeneration (28 cases), optic nerve lesion (22 cases), retinopathy of prematurity (13 cases), coloboma malformations (13 cases), severe congenital myopia (12 cases), congenital glaucoma (10 cases), congenital nystagmus (8 cases), congenital achromatopsia (6 cases), retinal abnormalities, and ocular injuries. We discuss these results, compare them with those of a similar study carried out in the same center in 1978, and briefly review the literature.

Adolescent↗
PubMed1988

[A new method for examining the vitreous body: the E1 Bayadi-Kajiura lens].

Vitreous examination is an important component of diagnosing and managing vitreoretinal disease, but the relative transparency of vitreous makes its examination difficult. Study of the vitreous is facilitated by the use of a biomicroscope to create an optical section and appropriate lenses to neutralize or modify the dioptric power of the eye. This article describes the vitreous examination using the preset El Bayadi-Kajiura lens, stretching the advantages and accuracy of this method. This lens is a +58,6 diopter preset lens producing an inverted real image between the slit lamp and the preset lens. This precorneal positive-diopter lens increase the refractive power of the eye, thus permitting biomicroscopic viewing of an ariel image, similar to the principle of indirect ophthalmoscopy. The major advantage compared to the Goldmann lens is the better visualisation of complex posterior vitreoretinal relationships, allowed by larger image, large illumination-observation angle and lower level of distortion and glare. The Goldmann lens permits a comprehensive intraocular examination, whereas with the EBK lens, observation and documentation of vitroretinal structures are limited to within 50 degrees of the fovea. Thus, the Goldmann lens is essential to evaluate more peripheral vitreous pathology. The Goldmann lens is more accurate in evaluating the presence of cells in the vitreous, which could be due to greater magnification. In a comprehensive examination of the vitreous, the Goldmann and EBK lenses are complementary. The latter is optimal for viewing complex posterior vitreous pathology; the former is necessary for viewing the peripheral vitreous. Photographic documentation of vitreoretinal relationship is better with the EBK than with the Goldmann lens.(ABSTRACT TRUNCATED AT 250 WORDS)

Eye Diseases↗