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Biomedical subjects

C Prünte

Publications and source records attributed to C Prünte.

34 records · Page 2Linked to original sources
PubMed1995

Indocyanine green angiographic findings in central serous chorioretinopathy.

There has been great controversy about the pathogenesis of the focal changes in the retinal pigment epithelium (RPE) causing detachment of the neurosensory retina in central serous chorioretinopathy (CSC). This study was performed to evaluate changes in choroidal perfusion in 15 patients with CSC. Fluorescein and indocyanine green (ICG) angiography was performed in patients with acute or chronic recurrent CSC. In all patients delayed arterial filling followed by capillary and/or venous congestion, in some cases adjacent to ischemic areas, was found in the choroid. Leakage from the RPE in fluorescein angiography was only observed in those areas with choroidal capillary and/or venous congestion. The preliminary results suggest that venous congestion possibly in association with ischemia causes hyperpermeability of choroidal vessels already described in the literature.

Acute Disease↗
PubMed1995

Enzymatic digestion increases permeability of the outer blood-retinal barrier for high-molecular-weight substances.

BACKGROUND: The purpose of the study was to investigate whether lysosomal enzymes can participate in damaging the outer blood-retinal barrier and to examine the role of glycosaminoglycans in maintaining the barrier function for high-molecular-weight substances. METHODS: The ciliary artery was cannulated in freshly enucleated pig eyes. Perfusion was performed with buffer (controls), with heparinase (substrate: heparan sulfate), or with lysosomal enzymes freshly prepared from pig retinal pigment epithelium at 36 degrees C, followed by perfusion with the tracer native ferritin (NF) or the marker cationized ferritin (CF). The eyes were examined by electron microscopy. RESULTS: In controls treated with buffer alone, NF was found in high concentration in the lumina of the choroidal capillaries; however, little NF was found in Bruch's membrane (BsM). The tracer did not penetrate to any extent beyond BsM. In eyes digested with heparinase or lysosomal enzymes, significantly higher numbers of tracer molecules were found in BsM. Furthermore, NF penetrated BsM and was apparent in the subretinal space and also inside retinal pigment epithelial cells, probably due to pinocytosis. CONCLUSIONS: The results indicate that heparan sulfate proteoglycan is important for the maintenance of the outer blood-retinal barrier and that lysosomal proteases may participate in damaging this barrier, causing increased permeability to high-molecular-weight substances.

Animals↗
PubMed1995

The novel dopamine D-1 antagonist and D-2 agonist, SDZ GLC-756, lowers intraocular pressure in healthy human volunteers and in patients with glaucoma.

PURPOSE: To investigate the intraocular pressure (IOP)-reducing effect and side effects of SDZ GLC-756, a novel dopamine D-1 antagonist and D-2 agonist, in control subjects and patients with open-angle glaucoma or ocular hypertension. METHODS: A single-application, randomized, placebo-controlled, double-masked study was performed. SDZ GLC-756 eye drops at a concentration of 0.01% (n = 6) or 0.1% (n = 6) were administered to one eye in control subjects, vehicle alone (control) to the contralateral eye. In glaucoma patients the trial was designed as a crossover study administering SDZ GLC-756 (0.1%) eye drops and vehicle alone (control) to one eye in 12 patients with open-angle glaucoma or ocular hypertension. RESULTS: In control subjects, IOP decreased significantly by 2.0 +/- 0.4 mmHg (P < 0.01) after treatment with 0.01% SDZ GLC-756 and by 4.7 +/- 0.5 mmHg (P < 0.001) after treatment with 0.1% SDZ GLC-756. In the glaucoma group, IOP decreased by 6.8 +/- 0.6 mmHg (P < 0.001) (range, 4-11 mmHg). In both groups, treatment with 0.1% eye drops resulted in a significant IOP-lowering effect for 6 hours, and for 3 hours with treatment with 0.01% eye drops. A significant IOP-lowering effect (P < 0.05) also was found in the contralateral eye. Except for slight conjunctival hyperemia lasting up to 30 minutes after drug application, no ocular or systemic side effects were observed. CONCLUSION: SDZ GLC-756 reduced IOP significantly for approximately 6 hours. However, due to the study design with repeated IOP measurements before drug administration, the clinical efficacy of the preparation used remains unclear. The only systemic or local side effect observed was slight conjunctival hyperemia. The simultaneous D-1 antagonistic and D-2 agonistic properties of SDZ GLC-756 may provide a new pharmacologic approach to treating glaucoma and ocular hypertension, which deserves further investigation.

Adolescent↗
PubMed1995

Quantification of optic nerve blood flow changes using magnetic resonance imaging.

PURPOSE: To evaluate the possibilities of magnetic resonance imaging (MRI) for quantification of pharmacologically induced changes in optic nerve microcirculation. METHOD: T2-weighted MRI sequences were used to image the eye, optic nerve, and frontal cortex in rats. Two sets of control images before and one set during Gd (DTPA) infusion were recorded. Blood flow values for two regions of the optic nerve (an anterior part, including the optic nerve head, and a more posterior part) and the frontal cortex were calculated by image analysis from the change in signal intensity, as already reported for cerebral blood flow. For each rat, a control experiment before drug administration and a second experiment 30 minutes after subcutaneous injection of either placebo (n = 7), timolol (n = 7), or SDZ GLC-756, a dopamine D-1 antagonist and D-2 agonist (n = 7), were carried out in a double-blind fashion. RESULTS: Mean basal blood flow values were found between 29.4 and 45.6 ml/100 g per minute in the anterior part of the optic nerve, 38.3 and 42.9 ml/100 g per minute in the posterior part of the optic nerve, and 68.0 and 75.0 ml/100 g per minute in the frontal cortex. Placebo and timolol did not cause significant changes. SDZ GLC-756 significantly increased blood flow by 238% +/- 65% in the anterior part and by 87% +/- 40% in the posterior part of the optic nerve. CONCLUSIONS: These results suggest that MRI provides quantification of optic nerve blood flow and that dopaminergic substances increase optic nerve blood flow.

Animals↗
PubMed1993

[Diagnosis of vascular occlusion of the posterior eye segment].

Retinal arterial occlusion, retinal vein occlusion and anterior ischemic optic neuropathy are commonly found diseases of the eye. In general the diagnosis is verified by ophthalmoscopic examination. Further diagnosis is necessary for evaluation of possible treatment and prophylaxis of following cerebral or ocular occlusive events. In occlusive diseases vascular dilatation, improvement of rheologic parameters and in some cases treatment of inflammation are the first therapeutic aim. Furthermore, the pathophysiologic origin of the vascular occlusion should be clarified for more specific prophylactic treatment. Diagnostic tools and possible therapeutic consequences are discussed.

Diagnosis, Differential↗
PubMed1992

[Model experiments of the outer blood-retinal barrier in vitro].

Because of the difficulty in conducting experiments on the outer blood-retinal barrier in vivo, we developed an in vitro model. Bovine retinal pigment epithelial cells were grown on semipermeable membranes, enabling separate manipulation of the apical and basal medium. As a parameter of barrier function, we measured the transepithelial resistance (TER). Barrier function was also tested with fluorescein. The transepithelial resistance increased under optimal culture conditions, in confluent cultures, by 200 omega and there was no fluorescein leakage. After exposure to trypsin in Ca/Mg-less medium or EDTA or after application of argon laser, we were able to induce a breakdown of the TER and fluorescein leakage. This happened immediately after laser exposure, 1 min after EDTA, and 4 min after trypsin application. We observed no morphological differences after breakdown of the barrier function on the intercellular connections compared to normal confluent cultures following EDTA or trypsin exposure. In all experiments there was a recovery of barrier function after returning the cells to control conditions. These first results demonstrate that our in vitro model is a sensitive method for investigating barrier function in retinal pigment epithelium in cell culture.

Animals↗
PubMed1991

[Ocular vasospasm. 1: Functional circulatory disorders in the visual system, a working hypothesis].

Patients with normal-tension-glaucoma and with visual field defects of non-known origin, often suffer from mild vasospasm in the fingers. The observation often be provocated by coldness or emotional stress and that these defects can very often be reduced by a treatment of the vasospasm led to the hypothesis that a functional dysregulation of the circulation in the visual system might occur.

Arousal↗
PubMed1991

[Ocular vasospasm. 3: Contribution of choroid angiography].

In patients with ocular vasospasm a disturbance of papillary blood flow is discussed. The peripapillary choroidal circulation is of great interest because it supplies the papillary circulation. The Indocyanine green video-fluorescence angiography provides evaluation of choroidal blood-flow. In some cases of ocular vasospasm disturbance of choroidal blood flow could be found. Examples of these cases are demonstrated.

Aged↗
PubMed1991

[Reference values for quantitative image analysis of indocyanine green video-fluorescence angiography].

Indocyanine green video-fluorescence angiography was performed in 46 healthy normal subjects between the ages of 20 and 81 years using a 30 degrees Zeiss fundus camera, an external light supply and a high resolution CCD camera. Pictures were directly stored in a picture analysis system based on a PC with a temporal resolution of 25 pictures per second. Using statistical picture analysis, choroidal blood-flow parameters were obtained in a round area of interest with a diameter of 8 degrees with the center in the fovea. The parameters include: the mean arterial filling time (AFT) and the mean capillary density (MCD) in the choroid. There was no correlation for one of these parameters with arterial blood pressure or intraocular pressure. All values for the AFT were on an equal level for normal subjects younger than 65 years. Older normal subjects in some cases had clearly increased arterial filling times. The density of the capillary network in the choroid was significantly reduced with increasing age, and there was reduced density of the capillary network in normals with myopia.

Adult↗
PubMed1988

Quantification of choroidal blood-flow parameters using indocyanine green video-fluorescence angiography and statistical picture analysis.

A method for indocyanine green video-fluorescence angiography of the human choroid is described using a 30 degrees fundus camera (C. Zeiss) with external light supply, a low-light-level TV camera, and a video recorder. Bloodflow parameters for the choroid were obtained from the video recording using a picture-analysis system (IBAS, Kontron). These included: the mean time for arterial, capillary and venous filling and a parameter corresponding to the amount of perfused capillaries in the choroid. Angiograms were performed on normal, healthy subjects at normal and increased intraocular pressures and on patients with dry senile macular degeneration. Examples of the results are shown and discussed.

Aged↗
PubMed1986

Microcirculation in the conjunctival capillaries of healthy and hypertensive patients.

To study the impact of hypertension on conjunctival circulation, one group of healthy individuals and three groups of hypertensive patients (different stages of disease) were examined. Each participant had to undergo videomicroscopy to determine erythrocyte velocity in conjunctival capillaries, reactive hyperaemia and the diameter of the erythrocyte column within the vessels. Compared to healthy subjects, erythrocyte velocity and the diameter of the erythrocyte column were markedly increased in hypertensive patients. Furthermore the normalization of the erythrocyte velocity after a period of hypoxia was impaired in the hypertensives. These results indicate that changes in microcirculation due to hypertension can be detected by video microscopy.

Adult↗
PubMedDate not supplied

The influence of sex difference in measurements with the Langham Ocular Blood Flow System.

PURPOSE: To assess sex difference and parameters possibly accounting for such a difference in healthy subjects evaluated by means of the Langham Ocular Blood Flow (OBF) System. METHODS: Pulse amplitude of intraocular pressure (IOP) and pulsatile ocular blood flow (POBF) as measured with the Langham OBF System were assessed in 86 healthy men and 69 healthy women. RESULTS: Compared to men, women showed higher POBF (mean +/- SD: 722.6 +/- 152.8 versus 647.8 +/- 164.9 microL/min; P =.0056) and pulse amplitude (mean +/- SD: 2.3 +/- 0.7 versus 2.0 +/- 0.6 mm Hg; P =.0043) values. Sex difference was still significant after correcting for age, refraction, blood pressure, IOP, and pulse rate. Pulse amplitude correlated negatively with pulse rate, and POBF correlated negatively with IOP. Women had higher readings in pulse amplitude and POBF, even after correcting for age, refraction, IOP, blood pressure, and pulse rate. CONCLUSIONS: While using the Langham OBF System, one needs to be aware of sex difference that is independent of other hemodynamic parameters. How the observed difference in POBF is related to ocular blood flow, and how it might influence the preponderance of various ocular diseases in men or women remains to be clarified.

Adolescent↗
PubMedDate not supplied

Multicenter evaluation of tendency-oriented perimetry (TOP) using the G1 grid.

PURPOSE: The G1-TOP program is a short automated perimetric strategy which sub-divides the G1 grid of 59 points into four sub-grids. Each point is tested only once, but each patient's response is used to modify that particular point and the surrounding ones from the remaining sub-grids. This study compared the results of the G1-TOP program with the Standard Bracketing strategy. METHODS: Eleven participating institutions provided data from 213 patients (406 eyes). The main group consisted of 284 glaucomas and 55 glaucoma suspects. Other groups included 31 eyes with neurological disorders, 20 with chorioretinal lesions and 16 normal eyes. Mean age was 62.7 +/- 15.4 (range 14-88) years. All subjects had previous perimetric experience and visual acuity better than 0.5. Examination included G1-Standard Bracketing and G1-TOP testing, in interchangeable order, with the Octopus 1-2-3 perimeter. RESULTS: The correlation coefficient for mean defect (MD) was 0.95. Standard error (YX) for MD, square root of loss variance (LV) and individual thresholds were 1.86 dB, 1.29 dB, and 4.72 dB, respectively. Mean sensitivity values were similar (difference 0.04 +/- 1.87 dB) (p>0.05). Mean duration for G1-TOP was 2.19 +/- 0.26 min, while G1-Standard Bracketing took 11.51 +/- 1.52 min (ratio 1/5.1, or a net reduction of 80.4%). The sensitivity of G1-TOP versus G1-Standard Bracketing was: glaucoma 77.1/78.5, glaucoma suspects 38.2/47.3, neurological disorders 87.1/87.1 and chorioretinal lesions 80.0/85.0. CONCLUSIONS: The G1-TOP program gave very similar results to G1-Standard Bracketing in only 20% of the time required by the standard strategy.

Adolescent↗