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Biomedical subjects

D Schweitzer

Publications and source records attributed to D Schweitzer.

At least 55 records · Page 3Linked to original sources
PubMed1994

Anterior cruciate ligament reconstruction with fresh-frozen patellar tendon allografts.

A prospective study was performed on 30 patients who underwent an anterior cruciate ligament reconstruction with fresh-frozen patellar tendon allograft. An arthroscopic technique alone was used in 10 patients, and in the other 20 patients this was combined with a miniarthrotomy. After a mean follow up of 35 months, the overall functional results were satisfactory in 85%. There were no cases of infection, disease transmission or tissue rejection. Fresh-frozen patellar tendon allografts are a good method of anterior cruciate reconstruction.

Adolescent↗
PubMed1993

[Substance analytic studies of the effectiveness of laser coagulation in diabetic retinopathy].

An order to optimize photocoagulation in diabetic retinopathy, it is necessary to have objective criteria concerning substance-specific fundus changes like blood, melanin, xanthophyl, cytochrome aa3, and light scattering. By means of fundus reflectometry macular reflectance spectra can be measured and are different in normals and in diabetics before or after treatment. If logarithmic difference spectra are used only pathological alterations or changes caused by the coagulation are demonstrable. These difference spectra can be approximated by a linear model function containing the extinction spectra of the substances mentioned above and a term for light scattering. Spectra deconvolution delivers coefficients, describing differences in the substance concentrations between diabetics before and after treatment and age-matched normals. When we examined these coefficients, we found that neither their behavior in diabetic retinopathy nor their reaction to photocoagulation is unique. Thus, it might be possible to obtain references to patient-specific adapted coagulation by deconvolution of the macular reflectance spectra measured before treatment. Classification of the patients in specific types of reaction, according to the shape of the logarithmic difference spectra or the results of the spectra deconvolution, could be a step in deciding on the success of the therapy on a case-to-case basis.

Adult↗
PubMed1992

Spectrometric investigations in ocular hypertension and early stages of primary open angle glaucoma and of low tension glaucoma--multisubstance analysis.

The approximation of logarithmic difference spectra between the reflectance of the normal fundus and the fundus reflectance in different stages of glaucoma is demonstrated by a model. The influences of fundus pigments like oxihemoglobin, melanin, xanthophyll and rhodopsin as well as the intensity and the exponent of the scattered light are optimized. Glaucomatous alterations in the extinction of these pigments and of the scattering parameters are different in the macula, in the papillo-macular bundle and in the parapapillary region temporal to the optic disc. A lack of oxihemoglobin only in the papillo-macular bundle in first relative losses in the visual field function points to a damaged microcirculation in early POAG. In progressive glaucoma the extinction spectrum of xanthophyll is detectable in the papillo-macular bundle. A decreased intensity of the scattered light and an altered scattering exponent are suggestive of a damage in the nerve fiber layer at early stages of glaucoma.

Adolescent↗
PubMed1992

[Spectrometry for determining hematoma duration in vivo].

Spectroreflectometric measurements in the range of 430 to 700 nm were carried out in order to check this new method with regard to its application to determine time of haematomas in living humans. For this purpose 52 cases with artificial superficial skin haematomas and 40 patients with pure "monocle-haematomas" were investigated. Wavelengths of 560 and 580 nm indicate the best results. There are significant differences in cases with "monocle-haematomas" if the age difference of the haematomas is more than two days.

Adult↗
PubMed1991

[Diagnosis of glaucoma using fundus spectrometry in areas outside the papilla].

As a result of the statistical evaluation of spectra on the basis of discriminant analysis, it can be stated that spectrometric measurements on fundus areas are suited for glaucoma diagnosis also outside the papilla. For early recognition of glaucoma, measurements of the papillomacular bundle are more sensitive than measurements in the parapapillary region. Late stages of glaucoma and normal findings are most reliably separated by measurements in the parapapillary region. With increasing severity of the glaucoma, the spectrum of the macular pigment can be demonstrated in the papillomacular bundle. A spectrometrically recognizable lack of erythrocytes documents an impaired retinal microcirculation.

Adolescent↗
PubMed1991

[Multisubstance analysis. Detection of changes in the optical density in individual layers of the optic fundus].

A promising method for noninvasive objective diagnosis and monitoring of the course of a therapy is spectrometric investigation of the human ocular fundus. Application of this method in clinical practice depends on the development of suitable procedures for deconvolution of the measured spectra. The availability of microcomputers permits the performance of complicated calculations directly at the measuring device. Based on the two-photon flux theory, the influence of absorption and scattering in anatomically determined layers of the fundus will be considered. For this reason, an iterative principle for radiation transport into the fundus is introduced, allowing derivation of a physical model for calculation of the spectral course of the reflected light. In the multisubstance analysis a measured spectrum is approximated by the model function. During this analysis the optical densities of photosensitive and nonphotosensitive pigments and the reflection at intermediate layers can be calculated. As an example of multisubstance analysis, the deconvolution of foveal reflection spectra of normals and type I diabetics is demonstrated. This method makes it possible to show that early diabetic alternations occur in the choroid.

Adolescent↗
PubMed1985

Measurement of flow-physiologic parameters of retinal blood circulation in type 1 and 2 diabetics before and after photocoagulation.

In seven diabetics of type 1 and seven of type 2, the flow physiologic magnitudes were measured in a retinal quadrant before and after photocoagulation. The segmental blood flow, the arterial flow velocity, and the diameters of artery and vein are smaller after photocoagulation than before. Investigations into the time course of the flow-physiologic parameters following photocoagulation show that the flow-physiologic values are stationary about 2 weeks after photocoagulation.

Adult↗
PubMed1985

Reflectance spectrophotometry in the human ocular fundus.

Spectrometric investigations were carried out in normal human maculae and optic discs and in those with pathological findings (50 eyes in total). Reflection spectra were measured by illumination of various points of the fundus, using a highly sensitive photon-counting technique. It is necessary to distinguish diffusely reflected light from regularly reflected light, as we found marked differences in the spectra of diffusely reflected light between normal eyes and those with pathological findings. In optic atrophy cases, the intensity of light reflected from the optic disc (510-600 nm) was remarkably higher than normal. In findings of proliferative diabetic retinopathy, the reflected light intensity showed a steeper slope, beginning at 580 nm, in comparison with normal findings.

Diabetic Retinopathy↗
PubMed1985

Isolation of non-O1 Vibrio cholerae associated with enteric disease of herbivores in western Colorado.

Non-O1 Vibrio cholerae was isolated from a horse (Equus caballus), a lamb (genus Ovis), and two American buffalo (Bison bison) suffering from enteric disease in the western part of Colorado. In 1981, a foal died of apparent respiratory failure. Necropsy findings included heart failure and gastroenteritis. V. cholerae serovar 347 (Smith) was isolated from the colon of this animal. V. cholerae serovar 27 (Smith) was isolated in 1983 from the intestine of a feedlot lamb suffering from pneumonia and severe watery diarrhea. In 1984, an enteric disease occurred in a herd of American bison. The sick animals were depressed and separated from the herd, dying in about 3 days. Of approximately 100 adult bison, 7 died. Necropsy of one animal revealed that gross lesions were limited to the gastrointestinal tract. V. cholerae serovar 27 (Smith) was isolated from the abomasum, duodenum, and colon of this animal. A swab specimen from the intestine of another dead bison also yielded V. cholerae serovar 27 (Smith).

Animals↗