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Biomedical subjects

F Koenig

Publications and source records attributed to F Koenig.

At least 55 records · Page 3Linked to original sources
PubMed1986

[Erdheim-Chester disease. The multiviceral form presenting as exophthalmos].

Erdheim-Chester disease is a rare visceral xantho-granulomatosis, the 17th case of which is reported here. The initial symptom, bilateral exophthalmos, was uncommon. The picture was completed by a retroperitoneal xanthogranuloma and by bilateral and symmetrical osteosclerosis of the long bones. The lack of X-bodies at electron microscopy differentiated the disease from Hand-Schüller-Christian disease. The patient's condition improved with chemotherapy (vinblastine and doxorubicin) combined with corticosteroid therapy. After a 5-month remission period, he died of an intercurrent infection. No autopsy was performed.

Diagnosis, Differential↗
PubMed1985

[Exudative retinopathy with dominant transmission. Report of a new pedigree].

A family with the syndrome of familial exudative vitreoretinopathy is described. A 7-year-old presented a non-perfused, avascular periphery in the temporal retina. The father is blind and his fundus was described in childhood as showing vitreoretinal traction, retinal telangectasia and temporal fibrotic changes. A cousin of our patient, a 5-year-old girl, was seen with vitreoretinal traction of the posterior pole. Familial exudative vitreoretinopathy is sometimes confused with retrolental fibroplasia. The family history and a fluorescein angiographic study of non-affected members are useful for confirmation of this diagnosis: pathophysiologic mechanisms and optimal treatment of the disease still remain about discussion.

Adult↗
PubMed1984

[Effects of red krypton and monochromatic green argon lasers in the foveal region. A clinical and experimental study].

The destruction of senile neovascular membranes in the central avascular region of the macula using argon laser is difficult and associated with complications. Yellow pigment in this region absorbs the blue component of the conventional argon laser radiation. In this study, we compared laser of different wavelenghts: red krypton and green argon. Light and electron microscopic studies on non-human primates were performed at one hour and three weeks following laser burns. With the red krypton laser maximum damage was seen at the level of choriocapillaris and the choroïd, although the pigment epithelium was also destroyed. With the green argon laser the maximum absorption occurred at the level of the pigment epithelium. A clinical and angiographic study showed that the destruction of juxtafoveal neovascular membranes by both these lasers was possible after one or several treatment sessions. After an average follow-up period of 45 months, visual acuity was stable or improved in 10 out 17 eyes treated with the green argon laser and in 27 out of 53 eyes treated with the red krypton laser. Our results suggest that the red krypton laser offers a better alternative for the treatment of neovascular membranes located near the foveola since less unnecessary damage is induced. Outside the xanthophyllic area there is no major difference between the different wavelengths.

Animals↗
PubMed1984

[Angiographic aspects of senile macular degeneration: spontaneous course].

Between 1971 and 1981, 45 patients (50 eyes) with a senile macular degeneration were seen at an early stage of the disease. These patients were followed for 6 to 72 months (mean follow-up 32 months). The early morphological features and evolution of the lesions were analysed by fluorescein angiography. Three different angiographic types of subretinal new vessels were identified in this study. These were: angiographically visible vascular networks (27 cases) subretinal new vessels hidden behind retinal pigment epithelium modifications (9 cases); and subretinal new vessels associated with pigment epithelial detachment (14 cases). In the first group subretinal new vessels were clearly visible on the angiogram, as a distinct network of cart wheel-like capillary plexuses which fill very early in the arterial phase. Progressive leakage of dye hides this capillary plexus during the late phase. In the second group a pigment epithelial detachment, usually identified on biomicroscopic examination, was associated with neovascularization visible as a hyperfluorescent hot spot or as an uneven hyperfluorescence on the border of the RPE detachment. Other angiographic features are a non-circular shape, irregular filling of the pigment epithelial detachment, and uneven late hyperfluorescence. In the third group, occult neovascularization was usually located behind the retinal pigment epithelium. When subretinal neovascularization was suspected by the presence of a disciform lesion, angiography, showed an irregular pattern of delayed hyperfluorescence with late leakage. These features permit putative diagnosis without precise localization. This clinical study attempted to establish the evolution and prognosis of three clinical forms of subretinal new vessels, in order to more accurately establish the indications of photocoagulation treatment.

Aged↗
PubMed1983

Effects of sodium azide on phototaxis of the blue-green alga Anabaena variabilis and consequences to the two-photoreceptor systems-hypothesis.

Experiments with sodium azide support the earlier report that two different photoreceptor systems participate in the absorption of the phototactically active light in Anabaena variabilis. The one of them, represented by the phycobiliproteins and chlorophyll a, is responsible for positive and negative phototaxis around 440 nm and between 580 and 700 nm. This system is sensitive to sodium azide which is able to reverse the negative reaction at high fluence rates to a positive one. The second one which absorbs light between 500 and 560 nm and above 700 nm is insensitive to azide. It triggers only negative responses in absence and presence of azide as well. P750 is obviously not a photoreceptor pigment of this system, since there is no indication for its occurrence in Anabaena. Even photobleaching of the photosynthetic pigments at high fluence rates is prevented by azide. The noncyclic photosynthetic electron transport is not severely inhibited by azide because photokinesis is only in part impaired. Therefore, the hypothesis is suggested that the phototactic reaction-sign reversal generator of Anabaena is controlled by the level of an active oxygen species, probably singlet oxygen, which is quenched by azide.

Azides↗
PubMed1983

[Hemorrhagic macular choroidopathy in the young subject].

In a group of 182 patients of under 50 years of age with subretinal neovascularization, the syndrome of hemorrhagic macular choroidopathy of the young adult was identified in 30 cases. This syndrome is characterized by the occurrence of a juxtafoveolar idiopathic neovascular membrane in an eye normal in all other respects. The natural course of this lesion is the production of a fibroglial scar leading to a mean final visual acuity of 0.15. The syndrome remains unilateral in 75 p. cent of cases, as shown by a mean follow-up of 23.9 months. Photocoagulation of these new vessels is possible, and in a group of 19 eyes it allowed conservation of a mean acuity of 0.6. This syndrome differs from ocular histoplasmosis where widespread uni- or bilateral involvement of the pigment epithelium and choriocapillaris is found. Hemorrhagic macular choroidopathy can also be distinguished from choroiditis associated with hemorrhages. The existence or the sequellae of uveitis, even when associated with subretinal new vessels arising from an atrophic chorioretinal scar, establishes the correct diagnosis. The etiology of hemorrhagic macular choroidopathy is unknown. It is possible that multiple etiologic agents might be responsible for different clinical syndromes in relation to endemic factors.

Adolescent↗